記述言語：英語   掲載種別：研究論文（学術雑誌）

Bananas, a globally consumed staple, generate substantial agricultural waste, particularly peels and pseudostems, which account for over 60 % of the biomass. This waste presents an opportunity for value-added applications, especially in fire safety and thermal-resistant materials. In this study, dried banana pseudostems and peels were analysed for their thermal properties using Newton’s Law of Cooling. Key findings revealed that banana pseudostem outperformed the peel in thermal resistance, attributed to its higher lignin and cellulose content, which enhance insulation. These properties suggest that banana by-products hold significant potential for sustainable, thermally resistant materials, addressing fire safety challenges in regions like Malaysia. This research underscores the dual environmental and functional benefits of repurposing banana waste, aligning with sustainable development goals and promoting eco-friendly innovations.

DOI： 10.37934/ard.123.1.2333

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： https://doi.org/10.37934/arfmts.119.2.149159

DOI： https://doi.org/10.37934/arfmts.119.2.149159

Kyutacar

担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

DOI： 10.24507/icicelb.15.07.659

DOI： 10.24507/icicelb.15.07.659

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）

Kidney stones, known medically as nephrolithiasis, present a significant health concern globally, particularly in regions such as India and the Middle East. Despite extensive research, the complexity of ureteral obstruction due to kidney stones remains a challenge in urology. This study addresses this gap by analysing the effects of obstruction in a three-dimensional model of the ureter with a constant diameter, simulating various percentages of blockage. Through computational analysis, the pressure and velocity effects on the ureter wall are explored, providing insights into the dynamics of obstructed ureters. Building upon previous research, this study contributes to a deeper understanding of the factors influencing flow patterns and pressure variations within the urinary tract. Additionally, findings from this study may lead to advancements in non-invasive assessment methods for diagnosing and treating ureteral obstruction caused by kidney stones. Furthermore, insights gained from this research could potentially inform clinical decision-making, leading to improved management strategies and better outcomes for patients affected by this debilitating condition. The novelty of this work lies in its comprehensive analysis of the effects of obstruction on the ureteral wall, offering valuable implications for urological practice and patient care.

DOI： 10.1016/j.rineng.2024.102217

Scopus

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

Ureters are muscular tubes that transport urine from the kidney to the bladder. The peristalsis wave is responsible for carrying urine to the bladder. With the regular appearance of peristalsis, areas with anatomic narrowing junctions are crucial for ureteral diseases. A three-dimensional flow analysis is performed for different time steps to understand the effect of the urine bolus formation and the reflux phenomenon on variable diameter ureters. For the constant and variable diameter ureter, the pressure is obtained behind and in front of the propagating bolus respectively. The peristalsis wave creates the high-velocity of a jet in the neck region of the ureter. The contraction produces the trapping of the bolus leading to adverse flow in the contraction region. By virtue tapering, the high-pressure gradient builds up, leading to high wall shear in the ureter. The main goal is to determine the pressure, velocity, gradient pressure, and shear force on the ureter wall during peristaltic motion. These parameters are very important for clinicians to understand its effect in the unobstructed variable diameter ureter. This article may help to build a medical device for engineers. The physical significance of this information lies in its profound insights into the biomechanics and functionality of the ureters, which are essential components of the human urinary system.

DOI： 10.37934/cfdl.16.4.5468

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Ureters are essential components of the urinary system and play a crucial role in the transportation of urine from the kidneys to the bladder. In the current study, a three-dimensional ureter is modelled. A series of peristaltic waves are made to travel on the ureter wall to analyse and measure parameter effects such as pressure, velocity, gradient pressure, and wall shear at different time steps. The flow dynamics in the ureters are thoroughly analysed using the commercially available ANSYS-CFX software. The maximum pressure is found in the triple wave at the ureteropelvic junction and maximum velocity is observed in the single and double wave motion due to the contraction produced by the peristalsis motion. The pressure gradient is maximum at the inlet of the ureter during the single bolus motion. The contraction produces a high jet of velocity due to neck formation and also helps in urine trapping in the form of a bolus, which leads to the formation of reverse flow. Due to the reduction in area, shear stress builds on the ureter wall. The high shear stress may rupture the junctions in the ureter.

DOI： 10.1088/2057-1976/ad1f02

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Objectives: The geometry of carotid bifurcation is a crucial contributing factor to the localization of atherosclerotic lesions. Currently, studies on carotid bifurcation geometry are limited to the region near to bifurcation. This study aimed to determine the influence of carotid bifurcation geometry on the blood flow using numerical simulations considering magnitude of haemodynamic parameters in the extended regions of carotid artery. Methods: In the present study, haemodynamic analysis is carried out using the non-Newtonian viscosity model for patient-specific geometries consisting of both Left and Right carotid arteries. A 3D patient-specific geometric model is generated using MIMICS, and a numerical model is created using ANSYS. Results: The results obtained from patient-specific cases are compared. The influence of geometric features such as lumen diameter, bifurcation angle, and tortuosity on the haemodynamics parameters such as velocity, WSS, pressure, Oscillatory Shear Index (OSI), and Time-Averaged Wall Shear Stress (TAWSS) are compared. Conclusion: The results demonstrate significant changes in the flow regime due to the geometric shape of the carotid artery. It is observed that the lower value of TAWSS occurs near the bifurcation region and carotid bulb region. In addition, the higher value of the (OSI) is observed in the Internal Carotid Artery (ICA) and the tortuous carotid artery region. However, it is also observed that apart from the bifurcation angle, other factors, such as tortuosity and area ratio, play a significant role in the flow dynamics of the carotid artery.

DOI： 10.1016/j.clineuro.2024.108153

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Cardiovascular disease (CVD) is the major cause of death in many countries around the world especially in Malaysia. One of the most common CVD is heart valve diseases specifically aortic stenosis (AS) disease that occurs in elderly heart disease patients. Surgical aortic valve replacement (SAVR) is known as one of the most popular techniques for replacing new heart valves. For the past 15 years, transcatheter aortic valve implantation (TAVI) has become the current emerging solution and a good alternative to surgery for patients at very high or prohibitive surgical risk. TAVI has received great attention from broad research studies and clinical experiences due to the lower operative risk with shorter time of recovery compared to surgical aortic valve (SAV) replacement. This paper will review two TAVI devices (Edwards SAPIEN Valve TM and Medtronic CoreValve) that have seen wide application over the past 10 years and discuss the Malaysian practices on TAVI in accessing relevant information with evidence-based recommendations from clinical updates. Ultimately, these discussions will pave the way for new research areas for the improvement of future TAVI technology.

DOI： 10.1007/978-981-97-1920-4_9

Scopus

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

CiNii Research

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Falling down is a common and unintentional phenomenon, and the caused body injury may lead to loss of body function or even death. It is estimated that one out of every three older adult individual report a fall at least once every year of which 20% have serious consequence. To predict injury accurately and have better-targeted treatment after falling down, it is necessary to study the damage caused by falling down. To obtain reliable results similar to those of previous high-cost dummy experiments, more effective falling simulation methods should be developed. In this study, by using the biomechanical analysis software OpenSim (open-source software) with the proposed multi-body models associated with older adults’ declined muscle properties, we obtained the kinematic characteristics under different falling down situations for injury evaluation. Finally, the head peak acceleration under several falling down situations are served as the index to evaluate the injury and to obtain this influence of muscle strength decline. Regardless of aging, more positive self-protective can greatly help release the impact. And the declined muscle strength of older adults will higher the risk of fall injury under specific falling down posture.

DOI： 10.37934/aram.108.1.124132

DOI： 10.37934/aram.108.1.124132

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

In the immunological systems, neutrophil propulsion is considered to be driven by the concentration gradient of cytokines. However, the mechanism of propulsion has not been elucidated yet in previous research. In our investigations, assuming that neutrophil moves by the concentration Marangoni effect, the concentration gradient of cytokine on the neutrophil membrane was experimentally examined. The result showed that the cytokine concentration gradient on neutrophil membranes periodically changed. It indicates the possibility that neutrophils move while rotating under the cytokine concentration gradient. However, the neutrophil's rotation is difficult to be observed because experimental verification is limited due to the accuracy and sensitivity of the present measurement system. Therefore, no evidence has been found yet for a relationship between neutrophil velocity and rotation. In this study, assuming that the neutrophil is rotating, this relationship is investigated by theoretical and experimental approaches. As for the theoretical approach, the neutrophil velocity by the concentration Marangoni effect is calculated by using a special mathematical model. From this result, it was found that the velocity is high when the period is short. As for the experimental approach, to obtain the velocity and the concentration gradient on the membrane, neutrophil velocity and distribution of cytokine concentrations are observed with microscopy. In the experiment, the period of rotation was obtained from the time history of the concentration gradient by FFT (Fast Fourie Transform). From the results, the following three findings were obtained. At first, neutrophil velocity is not constant and vibrates. Second, when the rotation period is short, the velocity is fast. Third, when the distance between the neutrophil and the wall is close, the rotation period is longer and the velocity is lower. From these findings, it was concluded that neutrophil rotation is an important role in neutrophil’s propulsion mechanism.

DOI： 10.37934/arfmts.108.1.114125

DOI： 10.37934/arfmts.108.1.114125

Scopus

CiNii Research

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Indoor airflow patterns and air residence times significantly influence the spread of airborne infectious viruses, such as COVID-19. These factors can be quantified using computational fluid dynamics (CFD). In this study, CFD was utilized to assess the indoor airflow patterns and calculate air residence times in a typical restroom with high personnel flow and low ventilation efficiency. The results identified regions with high air residence times, indicating potential risk areas for airborne virus retention. Furthermore, the effects of different ventilation strategies on these high-risk areas were analyzed. Despite meeting air change standards, certain regions were found to potentially pose a higher risk due to prolonged air residence times. Based on these findings, recommendations for improving ventilation systems to reduce the risk of airborne virus infection were proposed. This study highlights the necessity of a more nuanced approach to indoor air assessment than simply calculating air changes per hour. It was concluded that (1) different ventilation strategies can greatly affect the air residence time in the room and (2) the variance of air residence time in the air circulation area are large in some locations, even with simple ventilation adjustments.

DOI： 10.37934/arnht.14.1.116

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Conjugated polymers (CPs) have emerged as excellent organic semiconducting materials for flexible electronic applications. CPs exhibit a notably fast carrier transport along their main π-conjugated backbone followed by inter-chain hopping compelling the need to form large and ordered domains in thin films. Therefore, the formation of larger domains, along with their orientation, is critical in controlling the electrical properties of CP-based organic electronic devices. However, controlling the molecular ordering along with the formation of large aggregates is a challenge. In this work, the unidirectional floating film transfer method (UFTM) has been utilized to prepare oriented thin films of CPs, which is a highly facile, cost-effective and material utilization efficient technique. We have demonstrated that extent and direction of molecular orientation in the fabricated thin films can be tuned along with the higher degree of aggregation. The rheological aspects, especially viscosity, play a significant role in determining molecular ordering along with the formation of these large aggregates. Active control of viscosity to achieve a stable interfacial viscous system is paramount to achieving this, resulting in a very high mobility of 12.4 cm2V−1s−1.

DOI： 10.1016/j.cej.2023.143932

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The carotid artery is a clinically important site in the human circulatory system as the consequences of its disease results in adverse outcomes like ischemic strokes, or death for too prolonged ischemia. Understanding the hemodynamics of this artery and its bifurcation are important. A method of treating the stenosis of this artery is Carotid Angioplasty and Stenting (CAS). This procedure results in a heavily modified hemodynamics or state of flow. To understand and predict this flow field modification Computational Fluid Dynamics (CFD) is an important computational tool. Further, the presence of a stent would affect hemodynamics. The aim of this work is to study these effects in patient-specific cases. The reconstructed patient-specific models will form the basis of the construction of the post-stenting carotid bifurcation models. A transient analysis was carried out to estimate the time-varying parameters in the fluid domains over a cardiac cycle as well as to gauge time average values over a cardiac cycle. Results are obtained for hemodynamic parameters, like wall shear stress, velocity, pressure, vorticity, and helicity, in both the prepared stenosed and stented geometries. It is seen that the stenting procedure leads to the renewal of the CCA to ICA flow path. But simultaneously the region in which the stent is present becomes a region of low TAWSS and contains areas of high OSI. These areas of low TAWSS and high OSI within the stented portions of the carotid bifurcations are indications for regions of possible restenosis. Therefore, the investigation demonstrates the likely region for future plaque growth. Further, the effects of widening of the lumen are also noted in comparison to the pre-stent cases.

DOI： 10.37934/cfdl.15.6.98114

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

The purpose of this study is to elucidate the mechanism of propagation of the laser-induced micro shock waves under condition where the micro bubbles are generated. In this paper, effects of generated micro bubbles on propagation of the laser-induced micro shock waves were investigated by CFD (computational fluid dynamics). Firstly, the two models (1-D model and 1-D spherical symmetric model) were computed for comparison of the peak pressure variation of the shock waves with propagation. As for governing equations for the propagation of the shock waves, continuity equation, Euler’s momentum equation and Tait’s state equation are used. From the computation, it is confirmed that attenuation of pressure of the 1-D spherical symmetric model was earlier than the 1-D model. In addition, the attenuation of the 1-D spherical symmetric model agreed with the laser-induced shock waves obtained experimentally. However, the peak pressure and duration time of the shock wave was not the same as the experimental result. Then, the bubble behavior was included in the computation of the shock wave propagation. As for the bubble behavior, Rayleigh-Plesset equation is used. From this computation, pressure wave was obtained which superposed the pressure of the shock wave on the internal pressure of the bubble. Although the duration time of the pressure wave was close to the experimental result, the value of the pressure was almost the same as atmospheric pressure. It is suggested that there is a possibility that phenomenon other than the bubbles is generated such as plasma when the shock wave is generated by focusing the femtosecond pulse laser.

DOI： 10.37934/arnht.13.1.1830

Scopus

CiNii Research

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Currently, Covid-19 is an epidemic all over the world. When virus directly adhere to mucous membrane of airway by breath, some humans maybe get inflammatory responses by viruses in the first stage of infection. The airway is composed of the nasal cavity, sinuses (Maxillary Sinus, Ethmoid Sinus, Frontal Sinus and Sphenoidal Sinus) and lungs. In the infection stage, the sinuses located in the nasal cavity tend to exhibit particularly high virus concentrations. Therefore, it is important to evaluate quantitatively the areas where viruses are likely to be adhered in the nasal cavity including sinuses. In this study, by CFD including concentration analysis the areas where viruses are likely to be adhered in the nasal cavity are predicted. As for the methods, the nasal cavity was made from 2D-CT image data by Itk-SNAP. For this computation in the nasal cavity continuity equation, Navier-Stokes equation and transport equation are used. And the transport of concentration was computed in the divided 4 parts of nasal cavity. As a result, it was found that the ratio of the concentration to the initial concentration in Ethmoid Sinus is approximately 0.6. It was found that Ethmoid Sinus is the areas where viruses are likely to be adhered and the areas can be predicted by computing the concentration.

DOI： 10.37934/arnht.13.1.96105

Scopus

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担当区分：最終著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Droplets including virus such as COVID-19 are easily influenced by the indoor airflow and spreading around everywhere. In general, areas with higher residence time of airflow in the room are more likely to have droplets. Therefore, it is important for predicting the infection risk to use the residence time. In this study, office models with ventilation devices are used and volume-averaged residence time is evaluated as indoor air quality. After making typical office models for the ventilation, indoor air flow motions were predicted by Computational Fluid Dynamics (CFD). By setting the proper boundary conditions for ventilation, effects of ventilation methods for ventilation devices were obtained. It was found that 1) by controlling the operation of devices, ventilation ability can be evaluated by calculating volume-averaged residence time, 2) the value of volume-averaged residence time depends on the degree of angles of device inlets, and 3) volume-averaged residence time for most areas can be decreased by opening a door.

DOI： 10.24507/icicel.17.10.1103

Scopus

CiNii Research

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Online  

Hemodynamics plays a major role in the development of numerous diseases and disorders, including atherosclerosis and stroke. Hemodynamic forces must be adequately mapped to precisely predict and avoid various illnesses and disorders. Blood is a complicated biological fluid that contains constituents, such as erythrocytes that cause it to behave in a non-Newtonian manner. This component is usually overlooked while studying carotid blood flow, and blood is modeled as a Newtonian fluid with constant viscosity. In the present study comparison of hemodynamics in carotid artery for Newtonian viscosity model and non-Newtonian Carreau-Yasuda (CY) viscosity model is done. Computational fluid dynamics analysis is carried out for four patient-specific healthy carotid artery models. The geometry of the carotid artery is obtained from a CT scan and a 3D model is generated using MIMICS. Blood enters the carotid artery through a common carotid artery (CCA) and splits into two arteries named internal carotid artery (ICA) and external carotid artery (ECA). The pulsatile velocity boundary condition is considered at CCA, and the pulsatile pressure boundary condition is considered for both ICA and ECA. The results obtained for both Newtonian and Carreau Yasuda's viscosity models are studied and compared. Wall shear stress is calculated and when compared, results obtained from the Newtonian viscosity model overestimates WSS in certain regions like CCA, ICA, and ECA.

DOI： 10.1007/978-981-19-6032-1_12

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Online  

Numerical simulations of cardiovascular flows have emphasized investigating the mechanics of blood flow in arteries. The objective of the current study is to examine the effect of Newtonian and non-Newtonian flow models in flow simulation to analyze for hemodynamic behavior. CFD analysis was performed on an idealized healthy abdominal aorta with renal branching using ANSYS Fluent solver. The discretized mesh was obtained having polyhedral and hexahedral grid ensured the capture of gradients with a sufficient number of grids. Transient analysis was performed using pulsatile flow boundary conditions. Velocity plots obtained from the analysis predict the recirculation zone in the Ostia of the renal artery. TAWSS observed to be maximum at the infrarenal aorta. And Newtonian model predicted higher TAWSS. Oscillatory shearing index calculated to be maximum at the bifurcation. The result of this analysis will be helping in understanding the flow behavior in idealized cases and further extended to stenosed cases.

DOI： 10.1007/978-981-19-6032-1_13

Scopus

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

DOI： https://doi.org/10.1299/jbse.22-00083

DOI： https://doi.org/10.1299/jbse.22-00083

記述言語：英語   掲載種別：研究論文（学術雑誌）

The application of numerical methods like CFD to understand hemodynamics in arteries has excellent potential to solve complex flow problems. In recent years, CFD has been primarily used in the hemodynamics of the carotid artery due to advances in computational resources. This technique is widely used to obtain knowledge on hemodynamics, predict the risk factors for the development and progression of the atherosclerotic lesion, and analyze local flow profiles due to changes in the carotid artery geometry. This fundamental study will be supportive in observing the blood flow behavior through arteries and studying arterial diseases. The present study investigates three different subject-specific carotid bifurcation models under altered blood pressure conditions. Subject-specific 3D carotid bifurcation modeling is carried out using Materialize software. Unsteady flow simulation is conducted in ANSYS Fluent under the rigid wall and Newtonian conditions. The haemodynamic parameters such as vorticity, helicity, and time-averaged wall shear stress (TAWSS) were evaluated to understand better the beginning and progression of atherosclerotic plaques in the bifurcation. Also, the influence of geometric variation in the bifurcation region was investigated, and it was observed that this region causes significant vortex formation zones. A noticeable reduction in velocity and backflow formation was observed, which reduced the shear stress. It is established that the regions of low TAWSS along the bifurcation region are likely to develop atherosclerosis.

DOI： 10.37934/arfmts.97.1.4761

DOI： 10.37934/arfmts.97.1.4761

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The ureter transports urine from the kidney to the bladder. During the peristalsis, the contraction of the ureter helps to move the urine in bolus form. In the current work, the ureter is modeled and a single peristalsis wave is used to know the effect of pressure and velocity at a different location in the ureter at different intervals of time for four inlet boundary conditions. A three-dimensional ureter model with 275 mm length is used in the current work. The analysis is carried out using a commercially available computational dynamic package ANSYS-CFX. A single sinusoidal peristaltic wave with a change in pressure is used for the analysis. The inlet pressure is varied as 0.1 Pa, 0.3 Pa, 0.5 Pa, and 0.7 Pa. The maximum pressure was found to be 1.28 Pa at an input pressure of 0.7Pa. In the neck region, a negative pressure of -1.03 Pa is observed at 0.1 Pa. At time T/4, it is observed that the maximum velocity of 0.0406 m/s at N1. In all the other time steps and locations, the minimum velocity of 0.017 m/s is observed. The reverse flow due to negative pressure will develop the urinary tract infection in the ureter and result in the bacteria and toxins from the ureter into the renal pelvis and kidneys.

DOI： 10.30919/es8d734

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

For the thrombus formation in medical fluidics, it is considered that stagnation of the flow, shear rate and adhesion on the wall are important physical factors. Affeld et al. suggested that shear rate distribution and particle adhesion distribution on the wall are important factors by their experiment of impinging jet flow with stagnation point, and also showed that adhesion mechanism of platelets on the flow field is also important by theoretical evaluation. However, the effect of platelet adhesion on white thrombus formation by shear flow is still now unknown. In this paper, to improve accuracy of the prediction for platelet adhesion, transport process of concentration on impinging jet flow based on Affeld et al.’s experiment is analyzed by finite difference CFD with modifying the thrombus evaluation model. In addition, distribution of concertation on the wall is tried to be evaluated by setting simple boundary conditions of concertation for platelets adhesion. It is concluded that the distribution of platelet adhesion on the wall surface can be predicted accurately by the proposed evaluation method composed of distribution of concentration, velocity and shear rate with adjusting the threshold.

DOI： 10.24507/ijicic.18.02.657

Scopus

CiNii Research

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

In ureter physiology, the peristaltic mechanism is involved in urine transport from the kidney to the bladder through the ureter. The constrictions in the ureter develop the critical regions for ureter disease. ANSYS-CFX is used to analyze the flow dynamics. Multiple peristalsis waves are made to propagate over the tapered ureter model to understand the formation of bolus and reflux effect. The effect of the peristaltic sinusoidal wave propagating along the tapered circular tube results in pressure, velocity, pressure gradient, and wall shear distribution inside the ureter. The maximum pressure is created by the urine bolus of the single wave as it flows in front of the ascending urine bolus. This creates a negative pressure gradient, which can lead to a reverse flow. The high wall shear stress may affect the function of the kidney and play an important role in various kidney diseases. In triple wave due to incomplete wave propagation at the end, the minimum pressure gradient is recorded at the neck region due to contraction in the area. Also, the velocity shows a reverse flow at the outlet and this may lead to some urinary infection in the ureter.

DOI： 10.30919/es8e615

Scopus

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記述言語：英語   掲載種別：記事・総説・解説・論説等（学術雑誌）

The mechanical heart valve (MHV) is commonly used for the treatment of cardiovascular diseases. Nonphysiological hemodynamic in the MHV may cause hemolysis, platelet activation, and an increased risk of thromboembolism. Thromboembolism may cause severe complications and valve dysfunction. This paper thoroughly reviewed the simulation of physical quantities (velocity distribution, vortex formation, and shear stress) in healthy and dysfunctional MHV and reviewed the non-Newtonian blood flow characteristics in MHV. In the MHV numerical study, the dysfunction will affect the simulation results, increase the pressure gradient and shear stress, and change the blood flow patterns, increasing the risks of hemolysis and platelet activation. The blood flow passes downstream and has obvious recirculation and stagnation region with the increased dysfunction severity. Due to the complex structure of the MHV, the non-Newtonian shear-thinning viscosity blood characteristics become apparent in MHV simulations. The comparative study between Newtonian and non-Newtonian always shows the difference. The shear-thinning blood viscosity model is the basics to build the blood, also the blood exhibiting viscoelastic properties. More details are needed to establish a complete and more realistic simulation.

DOI： 10.1155/2022/9612296

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The increase in cardiovascular diseases worldwide has resulted in higher death rate of people globally; the primary reason being atherosclerosis. A better understanding of this condition can be achieved through the application of numerical methods to understand the haemodynamics. The present study aims to investigate the effects of renal artery angulation on the flow characteristics in a non-critically stenosed artery compared to that of a normal artery in order to understand better, the reasons for causes and progression of renal artery stenosis. Abdominal aorta-renal artery models ranging from 30° to 90° angulations were generated from computerized tomography-angiogram slices, post which they were subjected to cleanup and defeaturing. Haemodynamic parameters such as velocity, pressure and time-averaged wall shear stress were evaluated at early systole, peak systole and peak diastole for the different artery models. Extensive amounts of flow recirculation were observed in normal renal arteries with higher bifurcating angles, whereas it was not the case in stenosed arteries where flow acceleration was seen for the duration of the cardiac cycle. Evaluation of static pressure encountered a similar trend where an increase in angulation saw a decrease in pressure for normal arteries which contradicted with stenosed artery results. Analysis of shear stress saw very similar trends in normal and stenosed arteries, with lower angulation profiles experiencing higher values of shear stress at the Ostia. In the cases of arteries of higher angulation with a non-critical stenosis, the possibility of worsening of stenosis into an opprobrious stage remains a concern.

DOI： 10.37934/arfmts.88.3.3148

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

As most previous studies on human falling down have been executed by experimental dummy tests, expensive instruments and complex configurations of the research environments are required. To decrease the cost of these experimental tests, it is necessary to develop prediction method for the body injuries caused by falling down through computer simulation. The purpose of this study is to investigate the effect of falling down postures on human injuries by computer simulation. To analyze falling down, the biomechanical analysis software OpenSim was used to rebuild a human model by Gait2354 (bone and muscle) model. Since body tissue cannot be included in dynamic simulation in OpenSim, contact points were added into appropriate part of the body model to imitate the effect of cushion of body structure. The kinematic characteristics of head during falling backward and forward were finally obtained by OpenSim and head injuries were evaluated by the acceleration on center of head. It was concluded that the head injury characteristics of different falling postures can be evaluated by comparing the kinematic results of different falling.

DOI： 10.24507/icicelb.12.12.1121

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The recent developments in computational fluid dynamics (CFD) can be useful in observing the detailed haemodynamics in renal artery bifurcation for clinical evaluation and treatment. The present study focuses on haemodynamic behaviour of blood as it flows through the abdominal aorta-renal artery junction in an idealistic healthy artery with varying bifurcation angles to the abdominal aorta, i.e. from 30° to 90° with increments of 15°. This is to examine the effect of angulation on the junction and to determine whether arterial geometry plays a role in the prediction of atherosclerotic lesions. The three-dimensional models used in this study were generated using ANSYS WORKBENCH 19.0, and numerical simulation was done using FLUENT 19.0 solver. The blood flow is assumed to be Newtonian, incompressible and laminar. Haemodynamic parameters such as velocity, wall pressure and wall shear stress along with flow variation are compared among the different models. As the angulation increased, velocity and wall shear stress at the ostial region decreased by 14% and 52% respectively. Wall pressure at the same region saw an increase by 3%. Therefore, renal arteries with higher bifurcating angles to the abdominal aorta were observed to be more prone to the formation of atherosclerotic lesions. The present study is a precursor for future studies on renal artery with stenosis

DOI： 10.37934/arfmts.88.1.149165

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Background and objective: The bladder receives the urine from the kidney and ureter. The series of peristaltic waves facilitate urine transport to the bladder. The peristaltic flow in the ureter is associated with fluid trapping and material reflux, which may cause an increase in bladder pressure. It is difficult to visualize the complex peristalsis phenomenon, in the ureter using image and radiography experiments. A numerical simulation will help in the understanding of urine bolus formation and its effect on the ureter wall. Methods: A three-dimensional computational fluid dynamic analysis is carried out to understand the flow physics associated with bolus formation and the effect of reflux on the ureter. ANSYS-CFX, a commercially available computational dynamics package is used to simulate the peristalsis. A single sinusoidal peristaltic wave traveling along a circular tube will yield the velocity, pressure, wall shear stress distributions inside the ureter. Results: The propagation of the peristaltic wave results in the backflow of urine near the inlet at the beginning of the flow. As the wave propagates towards the outlet, the flow rate decreases. It is observed that pressure distribution along the ureter axis will deteriorate towards the outlet. The contraction produces a very high-pressure gradient which causes the urine backflow. The trapping and the bolus formation cause a significant rise in bolus pressure, simultaneously developing negative pressure at the contraction neck. Conclusions: The effect of peristalsis on the ureter biofluid dynamic behavior of the ureter is visualized in this study. It is established that the peristaltic contraction results in high-pressure formation at the bolus and negative pressure at the neck. It was found to be a maximum of 1.1 Pa at the bolus center and —1.13 Pa at the neck region. At the ureter pelvis junction, a higher wall shear of 0.095 Pa is observed as the wave starts to propagate. The velocity vectors show that the trapping of urine causes reflux and results in an adverse pressure gradient near the wall. A maximum pressure gradient of 485 Pa/meter was observed at the contraction of the ureter wall.

DOI： 10.1016/j.cmpb.2021.106378

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Computational Fluid Dynamics facilitates in the quantitative analysis of haemodynamic processes of in vivo cardiovascular systems. The objective of the present study is to examine the effects of different branching angles of diseased renal arteries with respect to the abdominal aorta on its flow characteristics. Secondly, simulation of normal renal arteries at similar branching angles were also done as a baseline for comparison to comprehend if geometry played a role in the endothelial proliferation in renal artery stenosis. Idealistic renal artery models generated from the digital image of computerized tomography scan were used, with bifurcation angles at the junction ranging from 30° to 90° at successive intervals of 15°. Virtual stenosis of a degree below and above 80% by diameter were generated on the right and left renal artery respectively. The models were discretized using a hybrid polyhedral mesh. Parameters such as time-averaged velocity, time-averaged wall shear stress, pressure difference and fractional flow reserve were used to analyse the flow characteristics. Stenosed renal arteries with higher angulation was found to have larger flow recirculation zones, higher pressure gradient near the Ostia and was observed to experience greater amounts of shear stress at the region of stenosis. For the same degree of stenosis (above 80%), the blockage tended to increase from 18% to 25%, as the angle increased. The effect of angulation was observed to alter the flow characteristics significantly in the stenosed arteries. Critically stenosed (above 80%) renal arteries at a bifurcation angle above 45° showed signs of ischemia.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Paravalvular Leakage (PVL) has been recognized as one of the most dangerous complications in relation to Transcathether Aortic Valve Implantation (TAVI) activities. However, data available in the literature about Fluid Structure Interaction (FSI) for this specific problem are relatively limited. In the present study, the fluid and structure responses of the hemodynamics along the patient aorta model and the aortic wall deformation are studied with the aid of numerical simulation taking into account PVL and 100% TAVI valve opening. In particular, the aorta without valve (AWoV) is assumed as the normal condition, whereas an aorta with TAVI 26 mm for 100% Geometrical Orifice Area (GOA) is considered as the patient aorta with PVL complication. A 3D patient-specific aorta model is elaborated using the MIMICS software. Implantation of the identical TAVI valve of Edward SAPIEN XT 26 (Edwards Lifes ciences, Irvine, California) is considered. An undersized 26 mm TAVI valve with 100% valve opening is selected to mimic the presence of PVL at the aortic annulus. The present research indicates that the existence of PVL can increase the blood velocity, pressure drop and WSS in comparison to normal conditions, thereby paving the way to the development of recirculation flow, thrombus formation, aorta wall collapse, aortic rupture and damage of endothelium.

DOI： 10.32604/fdmp.2021.010925

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes enhancement of neutrophil motion by shock waves for developing new cancer immuno-therapy with changing environmental conditions such as temperature and working pressure related to initial pressure ratio to activate immune-cells. To obtain the chemotaxis performance of neutrophil, the neutrophil velocity is measured by working gradient of cytokine concentration. In this paper, effects of temperature in the surrounding liquid and working pressure related to initial pressure ratio (maximum pressure of shock wave) on the velocities were investigated. After working 5 shock waves on the suspension liquid of neutrophils, the velocity was measured by image processing on the microscopy. It was concluded that the neutrophil velocities in case of low temperature (10 C) were higher than that in case of high temperature (26 C). The other factor such as duration time of these temperature was discussed. It was also concluded that there should be optimized strength of shock wave to obtain the highest velocity by changing the initial pressure with consideration of surrounding temperature, and the highest amplitude of neutrophil velocity was 1.5 times higher than that without shock wave. ◦ ◦

DOI： 10.24507/icicelb.12.01.67

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. In our previous works, the transport of activated platelets (APs) on orifice flow has been simulated by finite difference method (FDM). And the distribution of AP concentration on the flow was obtained. However, the effect of platelet aggregation on the distribution of AP concentration can’t be investigated by FDM because FDM can’t simulate platelet aggregation. On the other hand, platelet aggregation has been simulated by dissipative particle dynamics (DPD). In this paper, a hybrid method combining FDM and DPD is proposed to investigate the effect of platelet aggregation on the distribution of AP concentration. And the hybrid method is used to simulate thrombus formation on orifice flow. As for the effect of platelet aggregation, it is found that the distribution of AP concentration in the hybrid method is different from the distribution in FDM at the places of platelet aggregation. It is considered that the difference is induced by platelet aggregation. As for the distribution of thrombus, higher AP concentration and more aggregated APs are found around the reattachment point and in the recirculation area. It is considered that thrombus is mainly distributed at these places in the simulation. And according to our previous experimental results, thrombus is mainly distributed around the reattachment point and in the recirculation area. It is concluded that the effect of platelet aggregation on the distribution of AP concentration can be investigated by the hybrid method, and the computational results agree with our previous experimental results.

DOI： 10.1080/10255842.2020.1755274

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記述言語：英語   掲載種別：研究論文（学術雑誌）

In this study, a numerical simulation has been conducted to understand the effect of angle of attack on the S5010 airfoil profile. ANSYS Fluent was utilized with the compliment of experimental data from literature. The 2-D computational fluid dynamic simulation were conducted to find the lift, drag and lift-to-drag ratio of S5010 airfoil at various angle of attack up till the stalling point. The k-ω SST turbulent model was used to model the turbulent flow during the simulation. The data obtained was compared with available experimental data for validity and later extended to obtain stall angle of the airfoil. It was found that the stall angle of S5010 airfoil was at 11 and the maximum lift-to-drag ratio was obtained at 7.8. Considering the simulation, acceptable solution has been achieved that can be used to compare with other airfoil profile in the future.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

This study investigated the impact of paravalvular leakage (PVL) in relation to the different valve openings of the transcatheter aortic valve implantation (TAVI) valve using the fluid structure interaction (FSI) approach. Limited studies were found on the subject of FSI with regards to TAVI-PVL condition, which involves both fluid and structural responses in coupling interaction. Hence, further FSI simulation with the two-way coupling method is implemented to investigate the effects of hemodynamics blood flow along the patient-specific aorta model subjected to the interrelationship between PVL and the different valve openings using the established FSI software ANSYS 16.1. A 3D patient-specific aorta model is constructed using MIMICS software. The TAVI valve identical to Edward SAPIEN XT 26 (Edwards Lifesciences, Irvine, California), at different Geometrical Orifice Areas (GOAs), is implanted into the patient's aortic annulus. The leaflet opening of the TAVI valve is drawn according to severity of GOA opening represented in terms of 100%, 80%, 60%, and 40% opening, respectively. The result proved that the smallest percentage of GOA opening produced the highest possibility of PVL, increased the recirculatory flow proximally to the inner wall of the ascending aorta, and produced lower backflow velocity streamlines through the side area of PVL region. Overall, 40% GOA produced 89.17% increment of maximum velocity magnitude, 19.97% of pressure drop, 65.70% of maximum WSS magnitude, and a decrement of 33.62% total displacement magnitude with respect to the 100% GOA.

DOI： 10.1155/2020/9163085

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2019 Author(s). Indoor cycling was commonly examined from the riding posture, saddle height or pedal force to analyze the muscular activity on cyclists' lower limbs. While strong muscular strength and proper riding posture are important to minimize strain, the significances of these attributes on cycling fatigue were unclear. An attempt was made to identify significant attributing features for indoor cycling fatigue classification based on an experimental study involving twenty healthy postgraduates. The participants were tasked to perform an indoor cycling fatigue experiment at 6km/h with gradual speed increment till fatigue level achieved. The accelerometry, sacral trajectory and the lower limb kinematic changes were measured. Significant feature subset selection was determined using the wrapper approach with IBk algorithm. The featured data were later classified on IBk, SMO, ZeroR, J48 and Vote followed by subsequent discriminant analysis. The results demonstrated that the significant attributes yielded 95.0% and 75% classification accuracies (training data) but yielded 72.5% and 65.0% (10 folds cross-validation) on Vote and the discriminant analysis respectively. Findings revealed that the cycle frequency is the most significant attribute exerting a major effect on cycling fatigue while StepRegML and Disp_ML attributes contribute little to distinguish fatigue and pre-fatigue cycling motion.

DOI： 10.1063/1.5121137

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2019, ICIC International. All rights reserved. To establish the prediction method of thrombus formation on the wall by computational fluid dynamics (CFD), it is very important to find out the effects of flow field on platelet adhesion on the wall. In this paper, the particle motions on impinging jet flow which has the stagnation point were analyzed, and the adhered particles on the wall were also analyzed. Especially, discrete particles by using the impinging jet flow that Affeld used for the platelet adhesion experiment were analyzed, and the adhesion mecha- nism of particles simulating platelets was investigated by CFD. This adhesion mechanism is corresponded to starting point for thrombus formation on shear flow. After analyzing three-dimensional flow field particle motions by using fundamental equations on the im- pinging jet flow, the platelet motions can be obtained. From the result of CFD comparing with experiment, it was concluded that the platelet motion was able to be simulated on the impinging jet flow by using particle tracking method with consideration of density dif- ference. It was also concluded that predicted adhered distribution did not agree well with experimental result even though the tendency of distribution of adhered platelet could be obtained. Further investigation and trials for this validation will be needed to establish the prediction method.

DOI： 10.24507/icicelb.10.08.755

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Singapore   Singapore   2019年07月14日  -  2019年07月15日

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Japan   Sendai   2019年06月10日  -  2019年06月12日

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018 International Association for Mathematics and Computers in Simulation (IMACS) The aim of this paper is to develop a new non-boundary fitted (NBF) Cartesian grid method to compute flows in a complex geometry such as that found in a human aorta. The algorithm is based on the volume of fluid (VOF) colour function in a regular Cartesian grid through the open source OpenFOAM platform. The solid was treated as a fluid with very high viscosity to theoretically reduce its deformability, and subsequently satisfy a no-slip condition at the boundary. We also introduced the artificial term of the colour function into an algebraic system of momentum equations, which had a significant impact on the non deformability of solid domain and originality of this study. The developed solver, NBF-VOF, is then thoroughly validated using a variety of numerical and experimental results available in the literature Finally, we demonstrated the applicability of our code on flows in a complex geometry based on patient-specific image data robustly without the need for complex meshing generation procedures that conventional boundary fitted (BF) methods do.

DOI： 10.1016/j.matcom.2018.11.014

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2019 World Scientific Publishing Company. In this work, a 3D urinary bladder was subjected to various pressure loading conditions mimicking the bladder filling volume. The bladder layer consisting of adventitia, detrusor and mucosa layer having different mechanical properties produced different deformation and stresses when subjected to the varying loads. The volume of the bladder changed to 231.34ml which was 128.91% higher than the assumed initial volume of 50ml on application of 18kPa of pressure. The detrusor layer which is thickest of the bladder wall reduced to 1.312mm from 4.4mm, recording a 108% change in its thickness at 18kPa pressure. The maximum von-Mises stress obtained were significantly higher in case of the Mucosa layer when compared to the detrusor and adventia layer. The unique layup of the bladder wall having different properties plays a major role in sustaining adverse pressure gradients and absorbing high stresses.

DOI： 10.1142/S0219519419500295

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018, ICIC International. All rights reserved. Platelet transport and aggregation are two important steps in the formation of white thrombus. Platelet transport has been investigated by finite difference method (FDM) in our previous research. However, FDM cannot simulate platelet aggregation. Other numerical methods, such as dissipative particle dynamics (DPD), should be used to simulate platelet aggregation. And DPD can be combined with FDM to have a complete analysis of the formation of white thrombus. However, vast computational time in DPD system is needed if particle number is big. To decrease this vast computational time and have a balance with FDM, parallel computation is an effective method. This paper describes the parallelization of DPD by OpenMP. For parallelization performance, it is found that the computational time is efficiently shortened by OpenMP. After the confirmation of the high performance by OpenMP, platelet aggregations with different initial platelet numbers are simulated in orifice flow. It is concluded that recirculation area and reattachment point have higher probability of platelet aggregation.

DOI： 10.24507/icicelb.09.07.665

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2018, ICIC International. All rights reserved. In this paper, to discuss asymmetricity of the thrombus formation on the wall surface, flow analysis on the three-dimensional flow in the pipe orifice was carried out, and the effects of asymmetricity of wall shear stress and shear stress on thrombus formation and hemolysis properties were investigated. As for thrombus formation, the asymmetricity of wall shear stress was obtained and compared with that of visualization of thrombus formation. As for hemolysis properties on orifice flows, it was evaluated by Lagrangian fatigue accumulation method in case of axisymmetric flow and three-dimensional flow. From the results, it was suggested that there is the possibility for wall shear stress and other transport process of concentration to influence circumferential thrombus formation. In addition to this, by comparing the hemolysis evaluation of the axisymmetric flow with the three-dimensional flow, it was also suggested that the flow asymmetricity has effects on hemolysis properties by comparing with axisymmetric flow.

DOI： 10.24507/icicelb.09.07.673

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Understanding of flow pattern behaviour inside the aorta contributes significantly in diseases treatment artificial design. Objective of present study is to simulate the blood flow in patient specific aorta using open source computational fluid dynamics (CFD) platform OpenFOAM. The real geometry was obtained from real male Malaysian patient. There are not much data available in literature incorporate real geometry of aorta due to complex geometry. The validation is done against existing experimental result of the 90 degree curve tube model. It was shown that our method is able to capture complex flow in the curve tube like secondary and separation flow that responsible for development of wall shear stress at the tube wall. These flow physics could have similarity in aorta blood flow. Finally, we apply our method with anatomy human aorta with pulsatile inlet condition. Further comparison is made with unstructured boundary fitted mesh. The final result shows that the detailed flow physics can be captured in an aorta.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

<p><i>In order to investigate various dangers of fall down, we have conducted the experiment using human dummy model in Japan Automobile Research Institute (JARI). We have measured accelerations inside of the head in time step of 1/10000 sec with the accuracy within 1%. From the acceleration, we calculate the time development of velocity and position of the center of the head. HIC and the deformation are calculated. for two backward falls from standing position. As a conclusion, we found the deformation of the skull is similar, about 2.4mm for two falls down, although their HIC are different from each other </i><i>. </i></p>

DOI： 10.24466/pacbfsa.30.0_225

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

<p><i>In this study, we evaluated the shock mitigation armor at the time of falling backwards, and as a result we found that armor protecting head and neck is the best result.</i> <i>Moreover, even if the shock was relieved, it was found that the armor where the head touches the ground is not suitable for a rearward fall </i></p>

DOI： 10.24466/pacbfsa.30.0_177

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

<p>This paper describes the relation between infantile crying and thrombus generation near intravenous indwelling needle in veins. In this study, it is assumed that the difference of pressure or flow rate between normal and infantile crying causes thrombus formation. First of all, the blood pressure of infant are measured, and the difference of blood pressure between normal status and infantile crying. It was found that the blood pressure increases according to the infantile crying, and the difference of blood is approximately 20 mmHg. To investigate the flow field of the flow, CFD analysis around the indwelling needle of drip injection (catheter) in the infantile vein was done. The results show that the increasing flow rate or velocity make the accumulation of particle around the inlet of the catheter.<b> </b></p>

DOI： 10.24466/pacbfsa.30.0_161

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記述言語：英語   掲載種別：研究論文（学術雑誌）

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Even though the mechanical heart valve (MHV) has been used routinely in clinical practice for over 60 years, the occurrence of serious complications such as blood clotting remains to be elucidated. This paper reviews the progress that has been made over the years in terms of numerical simulation method and the contribution of abnormal flow toward blood clotting from MHVs in the aortic position. It is believed that this review would likely be of interest to some readers in various disciplines, such as engineers, scientists, mathematicians and surgeons, to understand the phenomenon of blood clotting in MHVs through computational fluid dynamics.

DOI： 10.1007/s11517-017-1688-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）

In order to predict thrombus formation on high shear flows, previous thrombus model based on concentration transport was used. However, the model didn't consider the effect of shear on thrombosis. In this paper, a new model which considers the effect of shear is proposed. Platelet activation is an important process during thrombosis. In this model, reaction rate of platelet activation is redefined to be the product of agonist concentration and shear rate factor instead of original only agonist activation model. Using this new model, platelet transport and deposition are computed on high shear flows such as Couette flow and orifice flows. In case of Couette flow, the results show that number rate of activated platelets increases linearly with shear rate when shear rate is beyond its threshold. In case of orifice flow, the results show that platelet activation process is similar for every orifice configurations, but deposition rate of activated platelet differs from each other. The deposition rate depends on the shear rate in these orifices.

DOI： 10.1166/jmihi.2017.1841

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

Copyright © 2016 American Scientific Publishers All rights reserved. Developing a computational model to predict the abnormal flow characteristics and particle deposition produced by obstructive sleep apnea is an important step in learning the pathophysiology of Obstructive Sleep Apnea (OSA) disease. The objectives of this study are to investigate the airflow characteristics in the constricted airway region where obstruction could occur and to investigate the effect of abnormal airflow characteristics and microparticle deposition in the breathing airway due to pharyngeal occlusion. In this study, Computational Fluid Dynamics (CFD) analysis has been performed on an upper airway computational model with a constricted pharyngeal section representing Obstructive Sleep Apnea (OSA) disease. The different breathing rates of laminar and turbulent inspiratory airflows were simulated numerically through the upper airway model. The airflow characteristics and pressure distribution were analysed. A Lagrangian trajectory analysis approach was used to examine the transport and deposition of the injected microparticles through the nasal airways. The deposition fraction of the microparticles in a specific region through the upper airway model are presented. The results show that the morphology of the upper airway was found to significantly affect the airflow pattern and the deposition fraction of the microparticles. It was observed that, as the diameter of the particle increases, the location of the highest particle deposited will shift to the anterior part of the upper airway. The local deposition fractions proved that the upper airway plays a significant role in filtering large micro-particles.

DOI： 10.1166/jmihi.2016.1839

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Copyright © 2016 American Scientific Publishers All rights reserved. In this study, the fluid structure interaction (FSI) method was utilized to investigate the hemodynamic effects between normal aorta and aorta with Transcatheter Aortic Valve Implantation (TAVI) of paravalvular leakage (PVL). A 3D model of patient specific aorta with annulus diameter of 27.3 mm was developed using MIMICS software. In this research, a similar TAVI valve model by referring to SXT 26 Edwards SAPIENT valve was drawn using CATIA software with valve opening of 100%. The two way of fluid structure interaction analysis has been performed using ANSYS 14.5 software (ANSYS Inc. Canonsburg, PA, USA). The results revealed that the undersized TAVI valve lead to PVL. It was noticed that the PVL happened at the gap in-between the TAVI valve and annulus diameter which is not completely round in shape. This phenomenon produced recirculation flow at the right side of ascending aorta after the flow passing through the valve. It has been proven that the PVL caused a huge impact on the losses of the mass flow rate and also recirculation of blood flow which may lead to blood thrombosis. Furthermore, the data shows that PVL causes higher aortic wall deformation instead of normal aortic condition and may lead to migration of the valve. Consequently, PVL may cause other serious problems such as stroke, arrhythmias and coronary ischemia, which required reoperation.

DOI： 10.1166/jmihi.2016.1840

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

Motivated by the current interest in the numerical simulation of biological flows in the human body, we develop a new method to simulate fluid flow embedded in a solid region. The novelty of this method lies on the use of a fixed grid in the entire computational domain. The formulation is an extension of the multiphase fluid flow that belongs to the category of the penalty method, where high viscosity is imposed on a solid region. A free open source library, namely, OpenFOAM, is used to integrate high order and advanced numerical schemes into these computational formulations. The Monotone Upstream System for Conservation Laws (MUSCL) scheme by van Leer, with a harmonic limiter from the category of the total variation bounded (TVB) scheme, is used for cell face interpolation. The robustness and accuracy of the solver are compared with the benchmark test case, namely, the free fall of a solid sphere. The test case validates that the rigidity of the solid sphere is ensured with the selected high viscosity ratio. The accurate terminal velocity of the falling solid sphere proves the no-slip condition at the solid-liquid interface. As a real application implementation, the flow on a simplified idealized model of heart valve stenosis is presented.

DOI： 10.1166/jmihi.2016.1835

Scopus

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記述言語：英語   掲載種別：記事・総説・解説・論説等（その他）

DOI： 10.1166/jmihi.2016.1833

Scopus

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes mathematical analysis of bubble deformation near free surface, which is the model of a gas bubble in a microcapsule collapsed by shock waves for drug delivery systems. By reviewing the previous investigations related to the disintegration of polymer capsules including gas bubbles by shock wave, it has been found that these modes depend on gas ratio in the liquid capsule, membrane thickness, pressure amplitude and frequency. This paper focuses on the effects of initial internal pressure of a bubble and gas ratio on the deformation process by simplified mathematical model, and it is compared with the previous experiments. The results showed that (1) the gas ratio does not affect oscillation amplitude of radius if the initial pressure is more than 0.4MPa; (2) the tendency of amplitude of radius with changing gas ratio in analysis is similar to the experimental averaged radius. It was concluded that the gas ratio and initial internal pressure are important parameters to control for making the micro capsule including a gas bubble.

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper presents the performance of the parallel algorithm for simulating thrombus formation on pipe orifice flow by using a PETSc software library package. Since the computational cost for bio-fluid problems is very expensive, an efficient algorithm such as parallel computing is necessary in order to overcome this limitation. The parallel program reduces the computational time by dividing workload to calculate simultaneously for each processor or computer. This will help researchers and physicians for medical diagnosis and development of medical devices. The blood flow used in this analysis is modeled by the incompressible Navier-Stokes equations with a partially patched modified k − ϵ model. Moreover, the platelet adhesion model is used for predicting the formation of thrombus. We perform the numerical experiments on the orifice configuration. The results show that our program can reduce the computation time by increasing the number of processors.

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2016, ICIC International. All rights reserved. Accurate evaluation of turnover or fall accidents is necessary to understand the relation between HIC (Head Injury Criterion) and the way of falling. In order to investigate this problem, we have done the experiment in JARI using human-type robot which simulates the human accidental damage. The precise data of acceleration has been taken from three points of the robot (head, chest and pelvis), Using the acceleration data of head point, HIC has been calculated for two experiments. Furthermore, we construct the speeds and locations of the three points using the acceleration data of chest and pelvis. We found that there are two types of falling posture, convex and depression of the upper body, and this posture of falling is related on the largeness of HIC. Finally, we found the HIC of convex posture is smaller since the pelvis absorbs the shock of the impact.

DOI： 10.24507/icicelb.07.05.1007

Scopus

CiNii Article

CiNii Research

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2016 ICIC International. Electro-osmotic flow through a cylindrical tube is investigated numerically based on the finite difference method with the successive over relaxation (SOR) method using the Fortran language. The effect of the pressure weight parameter β and the tolerance τ of the SOR method on the SOR convergent rate and the maximum error of the continuity equation are examined. The results show that a low-value of β and a highvalue of τ give a good convergent rate of the SOR method. Moreover, the value of the external electric field plays an important role on the convergent rate of the SOR method but it has no impact on the maximum error of the continuity equation.

Scopus

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）

DOI： 10.1299/jsmemag.119.1172_420

CiNii Article

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（研究会，シンポジウム資料等）

This paper describes the visualization of thrombus formation on shear flows such as orifice flow and Cuette flow, and development of numerical simulation for predicting thrombus formation by transport equation. Using the transparent devices, the thrombus formation on the wall on shear flow is observed and obtained the rate of thrombus formation by image processing. The results showed that the thrombus rate is increasing with shear rate by changing geometries of orifice and rotational speed of Cuette flow. On the other hand, the prediction method using CFD including transport equation of species using modified shear dependent model in orifice flow and Cuette flow is developed. In this computation, activated platelet is evaluated. The results show that deposition rate of activated platelet is increasing with shear rate.

DOI： 10.11239/jsmbe.54Annual.S360

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2015 IEEE. Accurate evaluation of fall accidents is very important. We have done the experiment in JARI using human-type robot which simulates the human accidental injury. The precise data of acceleration has been taken from the robot. Using the acceleration data, the motion of the head center is derived. The speed and the position of the head center are determined under a realistic condition. The deformation of head surface is also calculated and was found that it is 1.0∼1.2 mm in a natural falling. The solutions of a long interval of 324 ms are shown.

DOI： 10.1109/ICIEV.2015.7334020

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

CiNii Article

その他リンク： http://ci.nii.ac.jp/naid/110010043852

記述言語：英語   掲載種別：研究論文（学術雑誌）

CiNii Article

その他リンク： http://ci.nii.ac.jp/naid/110009975693

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2015 The Institute of Electrical Engineers of Japan. In this study, we propose a new treatment method to sanitize ballast water contaminated with plankton and/or bacteria. This method is constituted of water cavitation and discharge plasma in this cavitation field. The 0.5% brackish water containing brine shrimp (2.5 × 10 < sup > 4 < /sup > and 1.25 × 10 < sup > 5 < /sup > m < sup > -3 < /sup > ) was treated in 60 s. Then, we saw no surviving plankton in the treated water. Similarly, the treatment of water containing Escherichia coli cells (4 × 10 < sup > 15 < /sup > m < sup > -3 < /sup > ) in 120 s completed the sterilization. We also observed the DNA damage and destruction of the cellular morphology after treatment. It seems that the mechanisms of sterilization are radical reactions and physical damage caused by shockwave, and radical reactions are dominant mechanism.

DOI： 10.1541/ieejfms.135.357

Scopus

CiNii Article

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記述言語：英語   掲載種別：研究論文（学術雑誌）

© 2015. In order to understand the damage of human body and the related phenom-ena, the experiment of falling has been done in JARI, and acceleration data are taken on the head, chest, pelvis and also neck (force) using a dummy robot, which simulates a human body. However, micro movement of the center in the brain and deformation of the skull has not been clear from the experiment. Therefore, we calculate precisely the propagation of the shock waves after hitting the head. We formulate the two dimensional models, which simulate the skull material, and calculate the microscopic disorder of the each points using precise numerical procedure based on the fourth-order Runge-Kutta method. Then we obtain several interesting features of the shock waves. As conclusions, it is shown that (1) one dimensional calculation includes an essential feature of the propagation. (2) Based on the two dimensional calculation, the estimated speed of the longitudinal shock wave is 5263m/s and traverse shock wave is 2727m/s. (3) The method is ensured by the fact that the energy and momentum conservation low hold while calculation.

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2014 IEEE. In this work, the 3D geometry of patient specific aorta was utilized to carry out CFD studies on the effect of different valve opening (45°,62.5° and fully opening) on the hemodynamic properties. The result shows that the lower valve opening induced jet flow and hampered the flow on the additional carotid arteries. Besides, the leaflets were subjected to extreme stress values having disastrous consequences. Consequently, stenosis which is characterized by weaker leaflets and low valve openings has serious impact on the well being of humans.

DOI： 10.1109/IECBES.2014.7047660

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

For cerebrovascular structure composed of complex branching hierarchy, there is a problem that the computational time of analyzing the global flow is vast. Therefore, a breakthrough is needed to simplify the structural information and to obtain the complex structure quantitatively for analyzing cerebrocirculatory system. In this paper, to clarify the relationship between the flow field and the dimension of the fractal, an attempt to build a one dimensional model of the brain vascular structure that takes account of the hierarchical structure is done using fractal dimensions. In addition to this, effects of interpolation for 3d reconstruction images on the fractal dimensions are also investigated. It is concluded that (1) effect of reconstructing MRA image on the flow analysis is large, and (2) the flow in the cerebral vascular structure is laminar flow by calculating fractal dimension.

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The purpose of this research presumed the survival rate that used ISS to be a chest injury value evaluation when the wheelchair falls. In AIS of a side fall and a back fall of the wheelchair, a maximum 2. The survival rate was about 60 percent in side fall. However, it has been clarified that the survival rate rises up to about 100 percent by equipping it with the bicycle helmet. © ICIC International 2014.

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Living assistance equipment is strongly needed not only by a machine centered safety but also the concepts of human centered safety. A risk has been commonly given by relative and comparative expressions, whose styles are various survival or death ratio. The choice of risk is judged from the weight-ratio of benefit and disbenefit for group members or each person, and the death ratio for the risk is almost reduced to below 10-5 ~10-6, and final judgments of accept or rejects for the criteria (level acceptable) depend on consciousness of social members. The ISS3 of TRISS mentions that the in- jured persons, being in death ratio 0.0035, are estimated as lifelong death ratio 5.8%, an average loss of life expectancy 2.7 years and an annual death rate 0.0007, if our life span is about 90 years and an operating time of the equipment reaches 4 hours every day. Those values are much smaller than ratio of automobiles or that of accidental death, and are same levels of the death rate of natural calamity. However, an estimation of TRISS becomes similar to that of ASCOT in the case of slight or severe injury, and accompanied with single trauma in the same region. © ICIC International 2014.

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

We solved numerical solutions for the one dimensional model of bone structure for various conditions. Our numerical calculations are precise to reproduce the energy conservation low under our time span, which insures the results are reliable. As our solutions, a regular oscillation can be obtained under the circular conditions without boundary. In the case of colliding the floor, the shock is transferred with a rapid speed, on the other hand, the collective motion is slow and agrees with the theoretical values. In the case of hitting with bat, two types of motion occur, i.e., macroscopic and microscopic. The macroscopic motion is CG motion, and the microscopic motion is oscillations inside and it remains forever. These two cases have different results in the final stage, i.e., kinetic energy of CG is completely different. There is a scaling low of one parameter, we call "effective mass", which determines the properties of solutions. © ICIC International 2014.

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

A new method of wastewater treatment using electric discharge in the water cavitation field formed by a large number of micro bubbles generated by high-speed water flow is proposed in this paper. Indigo carmine solution, which is a type of dye, with a concentration of 9 mg/liter was used as the specimen solution for demonstration of water treatment. The total volume of solution and the average speed of solution in the cavitation field were 20 liters and about 7.4 m/s, respectively. An absorbance decrease rate of 96% was obtained in 50 min of treatment time at the electrode distance of 2 mm and discharge power of 16 W. It was also found that the efficiency of decolorization was improved by changing the electrode location. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(4): 1-10, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22483 Copyright © 2013 Wiley Periodicals, Inc.

DOI： 10.1002/eej.22483

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

© 2014 IEEE. Accurate evaluation of fall accidents is needed on the effect of protectors such as helmet or safety cap to reduce the shock from the impact to head is very important. We have done the experiment in JARI using human-type robot which simulates the human accidental injury. The precise data of acceleration has been taken from the robot, then HIC has been calculated for all the experiment. We have done the least square analysis to analyze the effects of various situations (variables) for stepwise process. Finally we calculate separate effect of HIC (average) of each variable, which is most plausible. Form the result, It is concluded that the effect of the helmet is amazing, which reduces HIC by 5903. On the other hand, the effect of the safety cap is not so large, the reduction is 1833 (about one third of helmet). The increase of the cart and bicycle is similar. In this way, we determine the reduction values of HIC using least square method. This values are valuable to predict or summarize the various effects of the situation.

DOI： 10.1109/SCIS-ISIS.2014.7044906

Scopus

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

CiNii Article

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the effects of gradient of cytokine concentration on chemotaxis of neutrophile by observing the concentration transport with adding cytokine. The aim of this investigation is to control of neutrophile motion in liquid by concentration gradient for drug delivery systems. © 2013 Springer-Verlag.

DOI： 10.1007/978-3-642-29305-4_36

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes studies to understand the fundamental mechanism of the collision and fall induced human injury by using dummy in the experiment. In our dummy experiments, the dummy on the platform is collided by the other dummy and fallen on the ground. It is concluded that (1) the injury criteria are affected by the initial position and pose of dummy, (2) HIC (Head Injury Criteria) decreases under the safety area with helmet in all cases of these dummy experiments, although Nij (Neck Injury Criteria) does not decrease with helmet. © 2012 ISSN 1881-803X.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Micro movement of the center in the brain and deformation of the skull is calculated precisely without approximation from the acceleration data of 7 experiments of backwards falling down. The experiment has been done in JARI, and acceleration data are taken on the head, chest, pelvis and also neck (force) using a dummy robot, which simulates a human body. As a result, the whole picture of the falling and hitting becomes clear. It is shown that (1) the postures of falling are classified into 2 types, i.e., nearly same time hitting or delayed hitting of the pelvis. (2) Accelerations of the head are classified into 2 parts, i.e., head's decelerating period and hitting on the floor. (3) The depth is from 2{reversed tilde}3 mm, which indicates the deformation of the skull is around 2 mm. On the other hand, the height range from 1 cm to 7 cm, depend on the falling posture. (4) From the FFT analysis, we found several peaks, and the strong peaks are 600 and 1600 Hz, which correspond with two acceleration peaks. © 2012 ISSN 1881-803X.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

We have been studying the comprehensive risk adjustors of human injuries for falling, descent and glitch of intelligent machines, by utilizing dummies (Hyb-III) in JARI. We searched a relationship between physical Impacts on human body and medical trauma scale. Thus, we adopted the clinical indicator TRISS, which is composed of three types of risk adjustor - anatomic, physiological, and comorbid. And they could be easily combined so that information from all three sources is used to predict outcome of human injury. We conclude the level acceptable as TRISS > 0.980 if NISS < 4 and RTS > 7.8404. This level meant all AIS sores to be less than or equal to 1. © 2012 ISSN 1881-803X.

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記述言語：英語   掲載種別：研究論文（学術雑誌）

The speed with which society is ageing has made the continued ability of the elderly to perform activities of daily living (ADL) a major social issue. A variety of policies designed to deal with ageing have been implemented in response to this societal background. The present study focused on fractures, the major cause of difficulty for the elderly to maintain their ability to perform ADL. In this study, the impact force of falls was inferred from experiments using crash test dummies. The results indicated that the risk of fracture was greatly influenced by body position when falling as well as the physique and the patient fell. This information indicates that it would be possible to make a prior risk assessment for fractures due to falling by determining a physique via a patient survey at the time of hospitalization. © 2012 ISSN 1881-803X.

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

New method of water treatment for wastewater using discharge in water cavitation field, in which numerous micro bubbles were generated by high-speed water flow, was proposed in this paper. Indigo carmine solution, which is a type of dye, with a concentration of 9 mg/Liter was used as a specimen for demonstration of water treatment. The total volume of solution and average speed of solution in the cavitation field was 20 Liter and about 7.4 m/s, respectively. A reduction ratio of absorbance of 96% was obtained in 50 min of treatment time at an electrode distance of 2 mm and a discharge power of 16 W. Also it was found that the efficiency of decolorization was improved by changing the electrode location. © 2012 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.132.656

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

This paper describes the development of ballast water treatment systems using interaction of bubbles, shock waves and discharges. In this development, we have cavitation flows during nozzle and diffuser part (reactor) and discharge in this cavitation area. The aim of this investigation is to satisfy the IMO standard for ballast water treatment by using our special cavitation discharge water treatment system, and to modify the geometry of reactor part in the circuit by using simple measurement method of the bubble density and diameter. In this paper, it is concluded that (1) the disintegration rate of plankton (more than 50 μm) by using cavitation discharge is satisfied in IMO standard (D-2), (2) by simple measurement method, the result of bubble density distribution in the reactor almost agrees with the position of electro node for discharge optimized with efficiency in the previous experiment. © 2012 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaib.78.1043

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Accidents of falls and descents sometimes cause serious injuries, which made us propose criterion-models of human biomechanical impacts when various robots would come into future daily life. The collision's experiments using dummy dolls, which were supposed to direct contact between human bodies and robots, were performed in co-operation with JARI. And theoretical models based on the experiments, which we thought to describe processes of the accidents of the falls and descents, were proposed. The worst case of the falls and descents in our daily life was assumed to be the falls and descents from a high place, (chair, steps), and we attempted to estimate biomechanical impacts and injuries by performing the experimental image analysis. Finally, we approximately expressed the falls and descents of human bodies as motions of ridged bodies, and proposed a "theory of rotation and free fall" for human heads. And using the models, we estimated AIS and risk of trauma. © 2012 ICIC International.

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Accidents of fall and descent are increasing yearly. Accident of fall is a serious problem in healthcare institutions. Reported by previous studies, many of the accidents of fall occur in the night. Many of the nightfall accident are extremely dangerous, because night fall accident due to slip, slip fall is hitting head. Head injure is involved in the life. We conducted a study about the fall incidents at the risk of head fracture and acute subdural hematoma by using a dummy model. As a result of experiments, the risk of fall accidents involves angular velocity and HIC. Finally, this study was found to give high risk head injury by slip backward falling down. © 2012 ICIC International.

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

Collision Impact Index (CII) of each part of human body is proposed to express the shock due to fall or collision, and pattern recognition of the shock peaks is analyzed based on the proposed CII. The formula of CII is defined similar to HIC, the meaning of which is "the product of averaged acceleration powered and the time interval". In order to make clear the usefulness of the index CII, the experiment has been done in JARI, and acceleration data are taken on the head, chest and pelvis of a dummy robot, which simulates a human body. The acceleration data were measured in the step of 0.0001 second, and analyzed on the basis of the proposed formula of CII. As a result, it is shown that index CII is reasonable because: (1) the ratios have similar dependence in spite of the power, (2) only peak is selected by the power, (3) the selected time intervals are almost constant, although the width becomes narrow as the power goes large, (4) the pattern of the shock peaks based on the CII values is important for understanding of the features of the shock of the collision due to the fall or collision. © 2012 ICIC International.

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes development of DDS (drug delivery systems) microcapsule using underwater shock waves, especially (1) making polymer microcapsules including a bubble and analysis of a bubble deformation process in a polymer capsule by pressure wave, (2) making liposome microcapsules with different elastic membrane and disintegration tests by ultrasonic waves. © 2012 American Institute of Physics.

DOI： 10.1063/1.4749338

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes development of microcapsule using underwater shock waves, especially (1) the trial of making polymer microcapsules including a bubble and disintegration tests by shock waves, (2) analysis of a bubble deformation process in a polymer capsule by pressure wave, (3) the trails of making liposome microcapsules and disintegration tests by ultrasonic waves. Copyright © 2011 by ASME.

DOI： 10.1115/imece2011-63414

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes visualization of thrombus formation process on orifice flows by laser sheet beam. The aim is to investigate the effects of high shear stress or shear rate on the thrombus formation or thrombus formation rate. In addition, the experimental results are compared with the CFD results. As a result, it was found that the high shear rate region of the flow has large effects of the thrombus formation and prediction method based on CFD can be used. Copyright © 2011 by ASME.

DOI： 10.1115/imece2011-62986

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2010年04月  -  2010年04月

Recently artificial organs, especially rotary blood pumps, have been developed in the worldwide, but in this development, thrombus occurs in the pumps. In general, the main physical factors of thrombus formation are considered to be shear rate, wall properties for blood's adhesion. But, there are no proper CFD codes for predicting thrombus formations using physical parameters in shear flows. In this paper, new model for predicting thrombus formation by considering aggregation and adhesion force to the wall by lattice Boltzmann method is proposed, and the trend of thrombus's adhesion to the wall can be simulated more adequately than that of previous one. Copyright © 2010 by ASME.

DOI： 10.1115/IMECE2010-40859

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2010年04月  -  2010年04月

This paper describes development of microcapsule using underwater shock waves, especially (1) the trial of making smaller microcapsules including a bubble for shock wave drug delivery systems, and analysis of a bubble deformation process to have higher efficiency of disintegration by shock wave, and (2) the effects of gradient of cytokine concentration on neutrophile motion in liquid by observing the concentration transport process with adding cytokine for developing drug delivery systems Copyright © 2010 by ASME.

DOI： 10.1115/FEDSM-ICNMM2010-31242

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2010年04月  -  2010年04月

This paper describes visualization of thrombus formation process on orifice flows by laser sheet beam. The aim is to investigate the effects of shear stress or shear rate on the thrombus formation or thrombus formation rate. In this investigation, by visualization of the thrombus formation in blood plasma flow, it was found that the high shear rate region of the flow has large effects of the thrombus formation. Copyright © 2010 by ASME.

DOI： 10.1115/IMECE2010-38607

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow. Copyright © 2010 by ASME.

DOI： 10.1115/IMECE2009-10718

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, the thrombus formation in blood plasma flow is visualized, and modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow. Copyright © 2008 by ASME.

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the effects of gradient of cytokine concentration on chemotaxis of neutrophile by observing the motion in liquid with adding cytokine concentration. The aim of this investigation is to control of neutrophile motion in liquid by concentration gradient for drug delivery systems. © International Federation of Medical and Biological Engineering 2009.

DOI： 10.1007/978-3-540-92841-6_217

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, the thrombus formation in blood plasma flow is visualized, and modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow. Copyright © 2008 by ASME.

DOI： 10.1115/IMECE2008-67265

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes effects of shock waves on cells to certificate the angiogenesis by shock wave (pressure wave) in the clinical application such as ESW (Extracorporeal Shock Wave). Especially, to investigate the effects of shock waves on the endothelial cells in vitro, the cells worked by plane shock waves using shock tube apparatus are observed and measured in the microscope. The peak pressure working on the endothelial cells at the test case is 0.4 MPa. After working shock waves on suspended cells, growth rate (area per one cell and population of cells) are measured by image processing. It is found that the growth rate of the shock-worked cells from 0 to 4h is clearly high compared with control one. It is concluded that once shock waves worked, the cells have capacity to increase growth rate in vitro. This preliminary result will be applied to fundamental investigations about shock wave stimulus on several kinds of cells in future. Copyright © 2008 by ASME.

DOI： 10.1115/IMECE2008-68216

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems, evaluation of their mechanical properties and development of new driving mechanics of the microcapsules. Copyright © 2008 by ASME.

DOI： 10.1115/FEDSM2008-55320

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the effects of gradient of cytokine concentration on chemotaxis of neutrophile by observing the motion in liquid with adding cytokine concentration. The aim of this investigation is to control of neutrophile motion in liquid by concentration gradient for drug delivery systems. Copyright © 2008 by ASME.

DOI： 10.1115/FEDSM2008-55319

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

主要雑誌

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This article describes the prediction of index of thrombus formation in shear blood flow by computational fluid dynamics with the Lattice Boltzmann Method (LBM), applying to backward-facing step flow, which is a simple model of shear flow in the rotary blood pumps and complicated geometry of medical fluid devices. Assuming that the blood flow is a multiphase flow composed of blood plasma and activated fibrinogen, the effects of surface tension and adhesion force to the wall were added to the LBM computational model. It was found that the thrombus formation in the backward-facing step flow occurred just after the reattachment point and behind the step. These results corresponded to our observation results of thrombus formation. For the thrombus formation in every case of blood flow to be predicted, effects of threshold level of physical parameters such as shear rate and adhesion force (effective distance from the wall) were estimated. Moreover, it was also found that the predicted adhesion point on the wall agrees with the visualization of thrombus formation by predicting proper thresholds. © 2009, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

DOI： 10.1111/j.1525-1594.2009.00782.x

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2009年04月  -  2009年04月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

2009年04月  -  2009年04月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the effects of gradient of cytokine concentration on chemotaxis of neutrophile by observing the motion in liquid with adding cytokine concentration. The aim of this investigation is to control of microcapsule motion in liquid by concentration gradient for drug delivery systems. © 2009 Springer-Verlag.

DOI： 10.1007/978-3-642-03887-7_55

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, the thrombus formation in blood plasma flow is visualized, and normal FDM (Finite Difference Method) and modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow.

DOI： 10.1007/978-3-642-03882-2_292

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=77950182748&origin=inward

記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2008年04月  -  2008年04月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2008年04月  -  2008年04月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2008年04月  -  2008年04月

主要論文集（会議）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2008年04月  -  2008年04月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

2008年04月  -  2008年04月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2008年04月  -  2008年04月

主要論文集（会議）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2008年04月  -  2008年04月

主要論文集（会議）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2008年04月  -  2008年04月

主要論文集（会議）

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, the thrombus formation in blood plasma flow is visualized, and modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow. Copyright © 2007 by ASME.

DOI： 10.1115/FEDSM2007-37074

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=40449137403&origin=inward

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes effects of shock waves on cells to certificate the angiogenesis by shock wave (pressure wave) in the clinical application such as ESW (Extracorporeal Shock Wave). Especially, to investigate the effects of shock waves on the endothelial cells in vitro, the cells worked by plane shock waves using shock tube apparatus are observed by microscope. The peak pressure working on the endothelial cells at the test case is 0.4 MPa. After working shock waves on suspended cells, the disintegration, shape and growth rate (area per one cell and population of cells) are measured by image processing. It is found that the younger generation cells have small differences of shape index, and the growth rate of the shock-worked cells from 0 to 4h are clearly high compared with control ones. It is concluded that once shock waves worked, some of them are disintegrated, but the other has capacity to increase growth rate of cell culture in vitro. This preliminary result will be applied to fundamental investigations about shock wave stimulus on several kinds of cells in future. Copyright © 2007 by ASME.

DOI： 10.1115/FEDSM2007-37637

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes the prediction of index of thrombus formation in shear blood flow by computational fluid dynamics (CFD) with Lattice Boltzmann Method (LBM), applying to backward facing flow, which is simple model of shear flow in the rotary blood pumps and complicated geometry of medical fluid devices. Assuming that the blood flow is multiphase flow composed of blood plasma and solid protein, the effects of surface tension and adhesion force to the wall are added to LBM computation. It is found that the thrombus formation occurs just after the reattachment point and behind the step. These results correspond to our previous observation results. To predict thrombus formation in every case of blood flow, effects of threshold level of physical parameters such as shear rate, adhesion force (effective distance from the wall) are estimated.

DOI： 10.1299/kikaib.73.2433

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the effects of gradient of cytokine concentration on Chemotaxis of neutrophile by observing the motion in liquid with adding cytokine concentration. The aim of this investigation is to distinguish the driving force by Marangoni effects from amebic motion. Copyright © 2007 by ASME.

DOI： 10.1115/BioMed2007-38091

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems, evaluation of their mechanical properties and development of new driving mechanics of the microcapsules. Copyright © 2007 by ASME.

DOI： 10.1115/BioMed2007-38088

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Tokyo   2007年11月  -  2007年11月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Tokyo   2007年11月  -  2007年11月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Osaka   2007年10月  -  2007年10月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Niseko   2007年09月  -  2007年09月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

Germany   2007年07月  -  2007年07月

主要論文集（会議）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

USA   San Diego   2007年07月  -  2007年07月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

USA   Irvine   2007年06月  -  2007年06月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

USA   Irvine   2007年06月  -  2007年06月

記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：日本語   掲載種別：研究論文（学術雑誌）

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

In this paper, the models for predicting the thrombus formation with simple estimation method in the orifice flow are proposed by conventional CFD and Lattice Boltzmann method. It is concluded that the thrombus formation (thickness) was estimated using (1) shear rate and adhesion force to the wall independently, and (2) shear rate function with adhesion force.

DOI： 10.1007/978-3-540-36841-0_798

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems and evaluation of their mechanical properties. We have proposed drug delivery systems (DDS) using shock waves in order to apply micro/nano technology in the fields of biomedical engineering. In this system, a microcapsule including a gas bubble is flown in the blood vessel, and finally broken by shock induced microjet, then drug is reached to the affected part in the body as same as traditional DDS. In this paper, the mechanism for deformation and disintegration of capsules in our previous works is reviewed, and the trials of making special microcapsules are discussed. To determine Young’s modulus of capsule membrane mentioned above, the membrane is deformed by the aspiration device and the deformation is compared with computational result by FEM.

DOI： 10.1007/978-3-540-36841-0_817

Scopus

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes a fundamental investigation of a new shock wave application in a drug delivery system (DDS) using a microcapsule including a single gas bubble. In this study, to design effective disintegrated microcapsule using a microjet, bubble deformation by shock waves near a curved elastic wall, which is the model of this microcapsule, is observed in an optical shadowgraph system using a high-speed camera and analyzed by image processing. The results show that a bubble compresses after shock wave propagation and the minimum radius of the bubble decreases with its distance to the model wall. During its expansion, a bubble near the wall extends locally and sharply, and then collapses. This deformation speed is estimated of microjet speed. Deformation speed has the peak against the initial bubble position from the wall, and can be controlled by changing the kind of bubble gas, the position of the initial bubble, and the elasticity and curvature of the wall. Therefore, it is found that changing these parameters a microcapsule can control the degree of its disintegration.

DOI： 10.1299/jsmeb.49.755

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Okinawa   2006年10月  -  2006年10月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2006年08月  -  2006年08月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

2006年08月  -  2006年08月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

Korea   Seoul   2006年08月  -  2006年08月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

2006年08月  -  2006年08月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems, evaluation of their mechanical properties and angiogenesis using plane shock waves. We have proposed drug delivery systems (DDS) using shock waves. In this system, a microcapsule including a gas bubble is flown in the blood vessel, and finally broken by shock induced microjet, then drug is reached to the affected part. In this paper, the mechanism for deformation and disintegration of capsules in our previous works is reviewed, and the trials of making special microcapsules are discussed. To determine Young's modulus of capsule membrane, the membrane is deformed by the aspiration device and compared with computational result by FEM. As for angiogenesis using shock wave, the effects of shock waves under 0.4 MPa on cell growth rate is investigated. It is found that increasing rate of cell population by working shock waves is faster than the control cells. © 2006 American Institute of Physics.

DOI： 10.1063/1.2205483

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

代表的研究業績

記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

USA   Boston   2005年12月  -  2005年12月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2005年11月  -  2005年11月

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes fundamental investigation to apply penetration of micro jet to disintegrate microcapsules in Drug Delivery System (DDS). Deformation processes of a bubble near curved elastic wall by shock wave were observed by optical shadowgraph method using a high-speed camera. It is found that a bubble generates micro jet toward a wall and opposite side whose characteristics are affected by gas of bubble, position of an initial bubble, wall elasticity, and wall curvature. Therefore, changing them about microcapsule can control penetration force by micro jet.

DOI： 10.1299/kikaib.71.1762

Scopus

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes prototype of microcapsule including a bubble for Shock Wave Drug Delivery Systems and evaluation of their mechanical properties. Microcapsules are generated by dropping mixed solution of Sodium Alginate and Polyvinyl Alcohol (PVA) into Calcium Chloride solution (CaCl2) Young's modulus are estimated by an aspiration experiment and its numerical analysis. Liquid and gas are injected into the microcapsules on micromanipulation system by hand. The result showed that microcapsules generated by low concentration of Sodium Alginate, PVA, and CaCl2 are able to be injected by micropipette and to make the microcapsule including a bubble. Furthermore, we found the existence of threshold value of apparent Young's modulus between able or disable of injection on the assumption of visco elasticity of microcapsule shell.

DOI： 10.1299/kikaia.71.1088

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

カナダ   モントリオール   2005年06月  -  2005年06月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

アメリカ   Vail Spa   2005年06月  -  2005年06月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

カナダ   バンクーバ   2005年05月  -  2005年05月

記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：日本語   掲載種別：研究論文（学術雑誌）

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems and evaluation of their mechanical properties. We have proposed drug delivery systems (DDS) using shock waves in order to apply micro/nano technology in the fields of biomedical engineering. In this system, a microcapsule including a gas bubble is flown in the blood vessel, and finally broken by shock induced microjet, then drug is reached to the affected part in the body as same as traditional DDS. In this paper, the mechanism for deformation and disintegration of capsules in our previous works is reviewed, and the trials of making special microcapsules are discussed. To determine Young's modulus of capsule membrane mentioned above, the membrane is deformed by the aspiration device and the deformation is compared with computational result by FEM. Copyright © 2005 by ASME.

DOI： 10.1115/imece2005-80697

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes the prediction of index of thrombus formation in shear blood flow by computational fluid dynamics (CFD) with Lattice Boltzmann Method (LBM), applying to orifice-pipe blood flow and flow around a cylinder, which is simple model of turbulent shear stress in the high speed rotary blood pumps and complicated geometry of medical fluid machines. The results of the flow field in the orifice-pipe flow using LBM are compared with experimental data and those using finite difference method, and it is found that the reattachment length of the backward facing step flow is predicted as precise as that the experiment and the finite difference method. As for thrombus formation, from the computational data of flow around the cylinder in the channel, the thrombus formation (thickness) is estimated using (1) shear rate and adhesion force (effective distance) to the wall independently, and (2) shear rate function with adhesion force (effective distance), and it is found that the prediction method using shear rate function with adhesion force is more accurate than the method using the former one.

DOI： 10.1299/jsmec.47.1027

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Sendai   2004年11月  -  2004年11月

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

USA   Anaheim   2004年11月  -  2004年11月

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes fundamental investigation to apply penetration of micro jet to disintegrate microcapsules in Drug Delivery System (DDS). Deformation processes of a bubble near curved elastic wall by shock wave observed by optical shadowgraph method using a high-speed camera. It is found that a bubble generates micro jet toward a wall and opposite side whose characteristics are affected by wall elasticity, wall curvature and a position of an initial bubble. Maximum velocity reaches 77 m/s. which corresponds to 28 MPa as water pressure. Changing wall elasticity, wall curvature and an initial bubble position can control penetration force by micro jet.

DOI： 10.1299/kikaia.70.1269

Scopus

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記述言語：日本語   掲載種別：研究論文（その他学術会議資料等）

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Osaka   2004年03月  -  2004年03月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

kitakyushu   2004年01月  -  2004年01月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

This paper describes the trial of making microcapsules and deformation analysis of a bubble near the curved elastic wall using macro 2d model and plane shock wave. The prototype microcapsules are made by using micromanipulation systems. It is found that by controlling the initial position of a bubble from the wall and the curvature of the wall there is a point to have large deformation, which tends to be collapsed easily. This is one of the results to aid design of DDS or bioprocess for cell-integration. Copyright ©2004 by ASME.

DOI： 10.1115/imece2004-59675

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

Taiwan   Tainan   2003年11月  -  2003年11月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

オーストラリア   シドニー   2003年08月  -  2003年08月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes the effects of shear stress and exposure time on the prediction method for the Index of Hemolysis using computational fluid dynamics (CFD) with a modified turbulence model in an orifice-pipe blood flow, which is a simple model of turbulent shear stress induced hemolysis in a high-speed rotary blood pump. Using CFD with the partially patched modified k-ε model (LK (Launder-Kato) Zonal model), the results of the flow field in the orifice-pipe flow are compared with those of standard low Reynolds number k-ε model at whole region (standard model: STD), and it is found that the shear stress by the LK Zonal model is predicted more precisely than that by STD model by comparing the pressure loss in the orifice and the reattachment length in the experiments. As for hemolysis, from the computational data of orifice-pipe flow, the index of hemolysis is estimated using (1) only shear stress, and (2) shear stress and exposure time, and it is found that the prediction method using only shear stress is more accurate than the method using shear stress and exposure time. From these results, the most suitable estimation method to predict hemolysis is the prediction considering only shear stress and constant exposure time using CFD in rotary blood pumps.

DOI： 10.1299/jsmec.46.604

Scopus

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

Cancun, Mexico   2002年12月07日  -  2002年12月07日

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

Calgary   2002年08月26日  -  2002年08月26日

記述言語：英語   掲載種別：研究論文（その他学術会議資料等）

Kyoto   2002年07月24日  -  2002年07月24日

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes the fundamental investigations for developing new technology using shock waves and bubbles, such as drug delivery systems (DDS) and bioprocess for environmental protection. To understand the fundamental phenomena, the coupling oscillation problems between the deformations of the cell including a bubble and the flow when underwater shock waves propagating are analyzed using computational fluid dynamics (CFD) and optical visualization. For this analysis, the cell is modeled as a liquid droplet including a gas bubble. The effects of (1) the differences of acoustic impedance between internal and surrounding fluid and (2) the boundary motion of the cell on the flow field (density) are discussed using ALE (Arbitrary Lagragian-Eulerian) computational method. The result shows that the effects of the differences of the acoustic impedance and the existence of a bubble in a cell are large for the deformation process of the cell itself. For the optical visualization, deformation process of a bubble near the elastic wall is observed as a model of cell membrane by shock waves to analyze the behavior of the bubble in the cell or microcapsule. From this result, it is suggested that there should be optimized or critical point to have large deformation of the bubble while changing initial position and initial diameter of the bubble in the cell and relative curvature of the wall (cell diameter), which may be enough to have large deformation to cracking the cell membrane. From these two results, it is found that if the proper parameters are selected, there are possibilities to make the large deformation enough to crack the cell membrane efficiently comparing with that has no bubbles when the shock waves and bubbles are applied to the fields of DDS or bioprocess.

DOI： 10.1299/jsmec.44.1031

Scopus

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes a numerical prediction method for hemolysis properties in orifice-pipe blood flows. In this study, several types of orifice-pipe flows by using two turbulence models are computed, which are ( 1 ) standard low Reynolds number k-ε model and (2 ) the k-ε model with partly patched Launder-Kato model (LK-Zonal model) to improve computational accuracy. These predicted flows are compared with (a) measuring pressure loss and (b) measuring reattachment length, and it is found that the flow using LK-Zonal model has good agreement with experiments. Then the hemolysis properties are estimated from the predicted flows. The results are 1) computational accuracy of orifice-pipe flow is improved by using LK-Zonal model, 2) accuracy of predicted hemolysis is also improved especially in orifice-pipe that have long contracted part.

DOI： 10.1299/kikaib.67.3119

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

2001年07月  -  2001年07月

記述言語：英語   掲載種別：研究論文（学術雑誌）

記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

2000年12月  -  2000年12月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes the improvement of accuracy for prediction of index of hemolysis in shear blood flow by computational fluid dynamics (CFD) with modified turbulence model, applying to orifice-pipe blood flow, which is simple model of turbulent shear stress induced hemolysis in the high speed rotary blood pump. Using CFD with partially patched modified κ-ε model (Launder-Kato partially patched model; LK-Zonal), results of the flow field in the orifice-pipe flow are compared with standard low Reynolds number κ-ε model at whole region (STD), and it is found that the shear stress by LK-Zonal model is predicted more precisely than that by STD model near the impinging flow region. As for hemolysis, from the computational data of orifice-pipe flow, the index of hemolysis is estimated in the same way as our previous paper(1), and it is found that the accuracy for prediction of index of hemolysis is also improved using LK-Zonal model in comparison with STD model, particularly in case of the orifice-pipe flow with large and long contracted part. From these results, the design method using CFD for the rotary blood pumps, that have impinging flow region to the wall, for suppressing the hemolysis can be proposed.

DOI： 10.1299/jsmec.43.853

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：英語   掲載種別：研究論文（学術雑誌）

主要雑誌

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes the effects of the particle inertia and the contact with the wall on hemolysis properties. The newly proposed methods of examining the inertia of red blood cells (particle) on particle path are discussed using computational fluid dynamics (CFD). In these methods, the particles are moved by Stokes drag including effects of difference of density between plasma and internal liquid in the blood. The results of computational analysis using these methods show that (1) the diameter of the particle (red blood cell), that is inertia of the cells, (2) the configuration of the objective wall boundary are important factors for this prediction. The results also show that if the inertia and the contact with the wall are considered, the precision of the prediction of the hemolysis properties will be improved comparing with that they are not considered.

DOI： 10.1299/jsmeb.43.225

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

主要雑誌

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1999年09月  -  1999年09月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

In this study, damage of living tissue cells (red blood cells and cancer cells) and experimental cell models (microcapsules) by plane shock waves is carried out experimentally. In addition, the effects of physical condition on the degree of damage are evaluated by constructing an appropriate mathematical model. To explain these phenomena, the red blood cells and the microcapsules are modeled mathematically as two spherical elastic shells filled with liquid. The fundamental equations express the oscillation of the spherical elastic shell in response to the incident pressure wave in the surrounding fluid. Frequency responses of the elastic shell model of two living tissue cells with mutual interaction in water are analyzed. From the results of this analysis, the effects of (1) the rise time of shock waves, (2) the distance between cells on shock-induced damage, (3) the concentration of suspended cells and (4) the incidence angle of shock waves are discussed. It is found that effects of these parameters are large in certain cases.

DOI： 10.1299/jsmec.42.640

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1999年07月  -  1999年07月

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes the particle inertia and the contact with the wall of red blood cells on the variance of particle path, that should depend on the hemolysis properties. The new methods of examining the inertia of red blood cells (particle) on particle path are discussed using computational fluid dynamics (CFD). In this method, the particles are moved by Stokes drag including effects of difference between density of plasma and internal liquid in the blood. The results of analysis by this method show that (1) the diameter of the particle (red blood cell) that means inertia of the cells, (2) the configuration of the objective wall boundary are important factor. These results also show that if the inertia and the contact with the wall are considered, the precision of the prediction of the hemolysis properties will be progressed.

DOI： 10.1299/kikaib.65.1621

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

主要雑誌

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1998年10月  -  1998年10月

記述言語：英語   掲載種別：研究論文（学術雑誌）

1997年12月  -  1997年12月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1997年07月  -  1997年07月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1997年07月  -  1997年07月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1997年07月  -  1997年07月

記述言語：英語   掲載種別：研究論文（学術雑誌）

主要雑誌

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes pressure wave analysis in order to examine the effects of shock waves on living tissues. From the comparison of displacements of living tissue models by FEM with that obtained by experiments, dynamic properties of living tissue (rat's kidney) are determined. Using these properties of the living tissues in shock compression (solid-state equation), the flow fields in two layers that consist of air and the living tissue, and in three layers that consist of air, water, and the living tissue are numerically obtained. It is found that the incident time derivative of pressure in the living tissue is smaller than that of pressure in air and water. Hence, the effect of the living tissue depends on the relaxation of pressure waves and duration of exposure.

DOI： 10.1299/jsmeb.39.714

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）

主要雑誌

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1996年07月  -  1996年07月

記述言語：日本語   掲載種別：研究論文（学術雑誌）

主要雑誌

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes a method of predicting hemolysis induced by turbulent shear stress (Reynolds stress) in simplified orifice pipe flow. In a centrifugal blood pump, serious hemolysis occurs at the impeller or the casing edge. The turbulent shear stress computed using a low-Reynolds number k-ε model near the edge proves to be several hundred times the laminar shear stress (molecular shear stress). The peak turbulent shear stress is about 2 500 Pa, which is much larger than that obtained from a conventional hemolysis test using viscometer. Then the threshold of turbulent shear stress for hemolysis is determined by comparing with that obtained in hemolysis experiments of pipe-orifice blood flow.

DOI： 10.1299/kikaib.62.1747

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）

主要雑誌

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This paper describes damage to living tissue cells induced by plane shock waves. It is an effective method for sensing injury to living tissue cells using pseudo-living cells. In this study, micro-capsules are used to estimate the degree of damage when subjected to shock waves. Mathematical models that can analyze displacement of living tissue cells and pressure in fluid when subjected to shock waves are evaluated. An elastic spherical shell is modeled to fit the biological data. Using stationary and transient analysis of spherical shell, the dynamic characteristics of the living cells (red blood cells and the micro-capsules) are obtained. The results show that damage to living tissue cells depends on (1) the elastic modulus of the cell, (2) the bulk modulus of intracellular material and (3) the thickness of cell membrane.

DOI： 10.1299/kikaib.62.613

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0030085712&origin=inward

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

This study proposes a method of predicting hemolysis induced by turbulent shear stress (Reynolds stress) in a simplified orifice pipe flow. In developing centrifugal blood pumps, there has been a serious problem with hemolysis at the impeller or casing edge; because of flow separation and turbulence in these regions. In the present study, hemolysis caused by turbulent shear stress must occur at high shear stress levels in regions near the edge of an orifice pipe flow. We have computed turbulent shear flow using the low-Reynolds number κ - ε model. We found that the computed turbulent shear stress near the edge was several hundreds times that of the laminar shear stress (molecular shear stress). The peak turbulent shear stress is much greater than that obtained in conventional hemolysis testing using a viscometer apparatus. Thus, these high turbulent shear stresses should not be ignored in estimating hemolysis in this blood flow. Using an integrated power by shear force, it is optimimal to determine the threshold of the turbulent shear stress by comparing computed stress levels with those of hemolysis experiments of pipe orifice blood flow.

DOI： 10.1111/j.1525-1594.1996.tb04479.x

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0030017653&origin=inward

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1995年07月  -  1995年07月

記述言語：日本語   掲載種別：研究論文（学術雑誌）

記述言語：日本語   掲載種別：研究論文（学術雑誌）

主要雑誌

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1993年12月  -  1993年12月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1993年07月  -  1993年07月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1992年12月  -  1992年12月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

sendai   1991年07月  -  1991年07月

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

1990年07月  -  1990年07月

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