The Experts below are selected from a list of 130446 Experts worldwide ranked by ideXlab platform
Yasuhiro Matsui - One of the best experts on this subject based on the ideXlab platform.
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performance of collision damage mitigation braking systems and their effects on human injury in the event of car to pedestrian accidents
Stapp car crash journal, 2011Co-Authors: Yasuhiro Matsui, Yong Han, Koji MizunoAbstract:The number of traffic deaths in Japan was 4,863 in 2010. Pedestrians account for the highest number (1,714, 35%), and vehicle occupants the second highest (1,602, 33%). Pedestrian protection is a key countermeasure to reduce casualties in traffic accidents. A striking vehicle's Impact Velocity could be considered a parameter influencing the severity of injury and possibility of death in pedestrian crashes. A collision damage mitigation braking system (CDMBS) using a sensor to detect pedestrians could be effective for reducing the vehicle/pedestrian Impact Velocity. Currently in Japan, cars equipped with the CDMBS also have vision sensors such as a stereo camera for pedestrian detection. However, the ability of vision sensors in production cars to properly detect pedestrians has not yet been established. The effect of reducing Impact Velocity on the pedestrian injury risk has also not been determined. The first objective of this study is to evaluate the performance of the CDMBS in detecting pedestrians when it is installed in production cars. The second objective of this study is to evaluate the effect of reducing Impact Velocity on mitigating pedestrian injury. Firstly, Impact experiments were performed using a car with the CDMBS in which the car collided with a pedestrian surrogate. In these tests, the Velocity was chosen for the various test runs to be 20, 40 and 60 km/h, respectively, which were based on the Velocity distribution in real-world pedestrian crashes. The results indicated that the Impact Velocity reduction ranged approximately from 10 to 15 km/h at the standing location of a pedestrian surrogate at both daytime and nighttime lighting conditions. These results show that the system has the potential to reduce pedestrian casualties from car-to-pedestrian contacts. Secondly, finite-element analyses were performed simulating vehicle-to- pedestrian Impacts with the THUMS pedestrian models. The vehicle models selected for the study included a medium sedan, a minicar, and an SUV. Since head and chest injuries are the most typical causes of pedestrian deaths in car-to-pedestrian accidents, the risk of head and chest injuries was calculated when the Impact Velocity was reduced from 50 km/h to 40 km/h, 30km/h, and 20 km/h. The results revealed that an Impact Velocity reduction of 10 km/h mitigated severe pedestrian injury at Impact velocities greater than or equal to 40 km/h. Specifically, a significant effect was observed in collisions with the medium sedan and SUV. In Japan, the CDMBS has just started to be installed in medium sedans. The pedestrian injury mitigation will be greatly improved if the system can be applied to various types of vehicles including SUVs in the future. Language: en
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performance of collision damage mitigation braking systems and their effects on human injury in the event of car to pedestrian accidents
Stapp car crash journal, 2011Co-Authors: Yasuhiro Matsui, Yong Han, Koji MizunoAbstract:The number of traffic deaths in Japan was 4,863 in 2010. Pedestrians account for the highest number (1,714, 35%), and vehicle occupants the second highest (1,602, 33%). Pedestrian protection is a key countermeasure to reduce casualties in traffic accidents. A striking vehicle's Impact Velocity could be considered a parameter influencing the severity of injury and possibility of death in pedestrian crashes. A collision damage mitigation braking system (CDMBS) using a sensor to detect pedestrians could be effective for reducing the vehicle/pedestrian Impact Velocity. Currently in Japan, cars equipped with the CDMBS also have vision sensors such as a stereo camera for pedestrian detection. However, the ability of vision sensors in production cars to properly detect pedestrians has not yet been established. The effect of reducing Impact Velocity on the pedestrian injury risk has also not been determined. The first objective of this study is to evaluate the performance of the CDMBS in detecting pedestrians when it is installed in production cars. The second objective of this study is to evaluate the effect of reducing Impact Velocity on mitigating pedestrian injury. Firstly, Impact experiments were performed using a car with the CDMBS in which the car collided with a pedestrian surrogate. In these tests, the Velocity was chosen for the various test runs to be 20, 40 and 60 km/h, respectively, which were based on the Velocity distribution in real-world pedestrian crashes. The results indicated that the Impact Velocity reduction ranged approximately from 10 to 15 km/h at the standing location of a pedestrian surrogate at both daytime and nighttime lighting conditions. These results show that the system has the potential to reduce pedestrian casualties from car-to-pedestrian contacts. Secondly, finite-element analyses were performed simulating vehicle-to- pedestrian Impacts with the THUMS pedestrian models. The vehicle models selected for the study included a medium sedan, a minicar, and an SUV. Since head and chest injuries are the most typical causes of pedestrian deaths in car-to-pedestrian accidents, the risk of head and chest injuries was calculated when the Impact Velocity was reduced from 50 km/h to 40 km/h, 30 km/h, and 20 km/h. The results revealed that an Impact Velocity reduction of 10 km/h mitigated severe pedestrian injury at Impact velocities greater than or equal to 40 km/h. Specifically, a significant effect was observed in collisions with the medium sedan and SUV. In Japan, the CDMBS has just started to be installed in medium sedans. The pedestrian injury mitigation will be greatly improved if the system can be applied to various types of vehicles including SUVs in the future.
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effects of vehicle bumper height and Impact Velocity on type of lower extremity injury in vehicle pedestrian accidents
Accident Analysis & Prevention, 2005Co-Authors: Yasuhiro MatsuiAbstract:In nonfatal passenger vehicle-pedestrian accidents, the lower extremities are the most commonly injured body parts. The European Enhanced Vehicle-safety Committee Working Group 17 (EEVC/WG17) pedestrian subsystem test method using a legform Impactor has been developed mainly for evaluation of aggressiveness of the front bumper of passenger vehicles. However, in recent years the number of sports utility vehicles (SUV) with a high bumper has been rapidly increasing. Since the bumper height is different between a passenger vehicle and an SUV, the type of lower extremity injury may be different. The type of lower extremity injury caused by this different bumper height should be clarified, because the test method and vehicle safety countermeasure must take into account a certain type of injury. Furthermore, the effect of vehicle Impact Velocity on the type of lower extremity injury in vehicle-pedestrian accidents has not been investigated so far. Therefore, the objective of this study is to clarify the effect of vehicle bumper height and vehicle Impact Velocity on the type of lower extremity injury in vehicle-pedestrian accidents. The Pedestrian Crash Data Study (PCDS), an in-depth accident database in the USA, was used for the current analyses. The results indicate that the type of injury, i.e., to the tibia and knee ligament, could become an injury to the femur with an increase in bumper height. Furthermore, the main injury at an Impact Velocity of around 20-30km/h is to the knee ligament. On the other hand, the main injury at an Impact Velocity of around 40km/h is a fracture of the lower extremities.
Koji Mizuno - One of the best experts on this subject based on the ideXlab platform.
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performance of collision damage mitigation braking systems and their effects on human injury in the event of car to pedestrian accidents
Stapp car crash journal, 2011Co-Authors: Yasuhiro Matsui, Yong Han, Koji MizunoAbstract:The number of traffic deaths in Japan was 4,863 in 2010. Pedestrians account for the highest number (1,714, 35%), and vehicle occupants the second highest (1,602, 33%). Pedestrian protection is a key countermeasure to reduce casualties in traffic accidents. A striking vehicle's Impact Velocity could be considered a parameter influencing the severity of injury and possibility of death in pedestrian crashes. A collision damage mitigation braking system (CDMBS) using a sensor to detect pedestrians could be effective for reducing the vehicle/pedestrian Impact Velocity. Currently in Japan, cars equipped with the CDMBS also have vision sensors such as a stereo camera for pedestrian detection. However, the ability of vision sensors in production cars to properly detect pedestrians has not yet been established. The effect of reducing Impact Velocity on the pedestrian injury risk has also not been determined. The first objective of this study is to evaluate the performance of the CDMBS in detecting pedestrians when it is installed in production cars. The second objective of this study is to evaluate the effect of reducing Impact Velocity on mitigating pedestrian injury. Firstly, Impact experiments were performed using a car with the CDMBS in which the car collided with a pedestrian surrogate. In these tests, the Velocity was chosen for the various test runs to be 20, 40 and 60 km/h, respectively, which were based on the Velocity distribution in real-world pedestrian crashes. The results indicated that the Impact Velocity reduction ranged approximately from 10 to 15 km/h at the standing location of a pedestrian surrogate at both daytime and nighttime lighting conditions. These results show that the system has the potential to reduce pedestrian casualties from car-to-pedestrian contacts. Secondly, finite-element analyses were performed simulating vehicle-to- pedestrian Impacts with the THUMS pedestrian models. The vehicle models selected for the study included a medium sedan, a minicar, and an SUV. Since head and chest injuries are the most typical causes of pedestrian deaths in car-to-pedestrian accidents, the risk of head and chest injuries was calculated when the Impact Velocity was reduced from 50 km/h to 40 km/h, 30 km/h, and 20 km/h. The results revealed that an Impact Velocity reduction of 10 km/h mitigated severe pedestrian injury at Impact velocities greater than or equal to 40 km/h. Specifically, a significant effect was observed in collisions with the medium sedan and SUV. In Japan, the CDMBS has just started to be installed in medium sedans. The pedestrian injury mitigation will be greatly improved if the system can be applied to various types of vehicles including SUVs in the future.
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performance of collision damage mitigation braking systems and their effects on human injury in the event of car to pedestrian accidents
Stapp car crash journal, 2011Co-Authors: Yasuhiro Matsui, Yong Han, Koji MizunoAbstract:The number of traffic deaths in Japan was 4,863 in 2010. Pedestrians account for the highest number (1,714, 35%), and vehicle occupants the second highest (1,602, 33%). Pedestrian protection is a key countermeasure to reduce casualties in traffic accidents. A striking vehicle's Impact Velocity could be considered a parameter influencing the severity of injury and possibility of death in pedestrian crashes. A collision damage mitigation braking system (CDMBS) using a sensor to detect pedestrians could be effective for reducing the vehicle/pedestrian Impact Velocity. Currently in Japan, cars equipped with the CDMBS also have vision sensors such as a stereo camera for pedestrian detection. However, the ability of vision sensors in production cars to properly detect pedestrians has not yet been established. The effect of reducing Impact Velocity on the pedestrian injury risk has also not been determined. The first objective of this study is to evaluate the performance of the CDMBS in detecting pedestrians when it is installed in production cars. The second objective of this study is to evaluate the effect of reducing Impact Velocity on mitigating pedestrian injury. Firstly, Impact experiments were performed using a car with the CDMBS in which the car collided with a pedestrian surrogate. In these tests, the Velocity was chosen for the various test runs to be 20, 40 and 60 km/h, respectively, which were based on the Velocity distribution in real-world pedestrian crashes. The results indicated that the Impact Velocity reduction ranged approximately from 10 to 15 km/h at the standing location of a pedestrian surrogate at both daytime and nighttime lighting conditions. These results show that the system has the potential to reduce pedestrian casualties from car-to-pedestrian contacts. Secondly, finite-element analyses were performed simulating vehicle-to- pedestrian Impacts with the THUMS pedestrian models. The vehicle models selected for the study included a medium sedan, a minicar, and an SUV. Since head and chest injuries are the most typical causes of pedestrian deaths in car-to-pedestrian accidents, the risk of head and chest injuries was calculated when the Impact Velocity was reduced from 50 km/h to 40 km/h, 30km/h, and 20 km/h. The results revealed that an Impact Velocity reduction of 10 km/h mitigated severe pedestrian injury at Impact velocities greater than or equal to 40 km/h. Specifically, a significant effect was observed in collisions with the medium sedan and SUV. In Japan, the CDMBS has just started to be installed in medium sedans. The pedestrian injury mitigation will be greatly improved if the system can be applied to various types of vehicles including SUVs in the future. Language: en
D Helfritch - One of the best experts on this subject based on the ideXlab platform.
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analysis of the Impact Velocity of powder particles in the cold gas dynamic spray process
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: M Grujicic, C L Zhao, W S Derosset, C Tong, D HelfritchAbstract:Abstract While built on a sound physical foundation, isentropic, one-dimensional models generally used to analyze the dynamics of dilute two-phase (feed-powder particles suspended in a carrier gas) flow during the cold-gas dynamic-spray process, require the use of numerical procedures to obtain solutions for the governing equations. Numerical solutions, unfortunately, do not enable an easy establishment of the relationships between the gas, process and feed-powder parameters on one side and the gas and the particle velocities at the nozzle exit and the particle Impact Velocity, on the other. Analytical solutions for the governing equations in the limits of small and large relative particle/gas velocities and a multiple non-linear regression analysis are used, in the present work, to develop analytical functions which can be used to compute the gas and the particle exit velocities and the particle Impact Velocity for a given set of the gas, process, and feed-powder parameters. The results obtained using the analytical functions are found to be in a very good agreement with their numerical and experimental counterparts.
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analysis of the Impact Velocity of powder particles in the cold gas dynamic spray process
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: M Grujicic, C L Zhao, W S Derosset, C Tong, D HelfritchAbstract:While built on a sound physical foundation, isentropic, one-dimensional models generally used to analyze the dynamics of dilute two-phase (feed-powder particles suspended in a carrier gas) flow during the cold-gas dynamic-spray process, require the use of numerical procedures to obtain solutions for the governing equations. Numerical solutions, unfortunately, do not enable an easy establishment of the relationships between the gas, process and feed-powder parameters on one side and the gas and the particle velocities at the nozzle exit and the particle Impact Velocity, on the other. Analytical solutions for the governing equations in the limits of small and large relative particle/gas velocities and a multiple non-linear regression analysis are used, in the present work, to develop analytical functions which can be used to compute the gas and the particle exit velocities and the particle Impact Velocity for a given set of the gas, process, and feed-powder parameters. The results obtained using the analytical functions are found to be in a very good agreement with their numerical and experimental counterparts. © 2003 Elsevier B.V. All rights reserved.
Sung R. Choi - One of the best experts on this subject based on the ideXlab platform.
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foreign object damage behavior in a silicon nitride ceramic by spherical projectiles of steels and brass
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Sung R. ChoiAbstract:Abstract Assessments of foreign object damage (FOD) of a commercial, gas-turbine grade, in situ toughened silicon nitride ceramic (AS800) were made using different projectile materials at ambient temperature. AS800 flexure target specimens rigidly supported were Impacted at their centers in a Velocity range from 100 to 450 m/s by spherical projectiles with a diameter of 1.59 mm. Three different projectile materials were used including hardened steel, annealed steel, and brass. Post-Impact strength of each target specimen Impacted was determined as a function of Impact Velocity to appraise the severity of local Impact damage. For a given Impact Velocity, the extent of FOD was greatest for hardened steel projectiles, least for brass projectiles, and intermediate for annealed steel projectiles. The key material parameter affecting FOD the most was identified as the hardness (or yield stress) of projectile materials. Prediction of Impact force as a function of Impact Velocity for each projectile material was made based on a quasi-static plastic model incorporated with the average ‘contact yield pressure’ determined from static indentation testing.
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effect of projectile materials on foreign object damage of a gas turbine grade silicon nitride
ASME Turbo Expo 2005: Power for Land Sea and Air, 2005Co-Authors: Sung R. Choi, Ramakrishna T Bhatt, Zsolt Racz, David N Brewer, John P GyekenyesiAbstract:Foreign object damage (FOD) behavior of AS800 silicon nitride was determined using four different projectile materials at ambient temperature. The target test specimens rigidly supported were Impacted at their centers by spherical projectiles with a diameter of 1.59 mm. Four different types of projectiles were used including hardened steel balls, annealed steel balls, silicon nitride balls, and brass balls. Post-Impact strength of each target specimen Impacted was determined as a function of Impact Velocity to better understand the severity of local Impact damage. The critical Impact Velocity where target specimens fail upon Impact was highest with brass balls, lowest with ceramic ball, and intermediate with annealed and hardened steel balls. Degree of strength degradation upon Impact followed the same order as in the critical Impact Velocity with respect to projectile materials. For steel balls, hardened projectiles yielded more significant Impact damage than annealed counterparts. The most important material parameter affecting FOD was identified as hardness of projectiles and was correlated in terms of critical Impact Velocity, Impact deformation, and Impact load.Copyright © 2005 by ASME
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foreign object damage of two gas turbine grade silicon nitrides in a thin disk configuration
ASME Turbo Expo 2003 collocated with the 2003 International Joint Power Generation Conference, 2003Co-Authors: Sung R. Choi, Michael J Pereira, Lesley A Janosik, Ramakrishna T BhattAbstract:Foreign object damage (FOD) behavior of two commercial gas-turbine grade silicon nitrides, AS800 and SN282, was determined at ambient temperature through post-Impact strength testing for thin disks Impacted by steel-ball projectiles with a diameter of 1.59 mm in a Velocity range from 115 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than SN282, primarily due to its greater value of fracture toughness (KIC ). The critical Impact Velocity in which the corresponding post-Impact strength yielded the lowest value was Vc ≈ 440 and 300 m/s for AS800 and SN282, respectively. A unique lower-strength regime was typified for both silicon nitrides depending on Impact Velocity, attributed to significant radial cracking. The damages generated by projectile Impact were typically in the forms of ring, radial, and cone cracks with their severity and combination being dependent on Impact Velocity. Unlike thick (3 mm) flexure bar specimens used in the previous studies, thin (2 mm) disk target specimens exhibited a unique backside radial cracking occurring on the reverse side just beneath the Impact sites at and above Impact Velocity of 160 and 220 m/s for SN282 and AS800, respectively.Copyright © 2003 by ASME
Sang Yong Lee - One of the best experts on this subject based on the ideXlab platform.
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observation of the spreading and receding behavior of a shear thinning liquid drop Impacting on dry solid surfaces
Experimental Thermal and Fluid Science, 2012Co-Authors: Sang Yong LeeAbstract:Abstract In the present work, the Impact dynamics of shear-thinning drops on dry solid surfaces was investigated and compared with that of Newtonian drops. The effects of liquid viscosity with shear-thinning characteristics, surface wettability and Impact Velocity on the spreading and receding behavior of the drops were investigated experimentally. Water, glycerin drops (Newtonian liquids), and xanthan drops (shear-thinning liquids) were impinged upon glass, stainless steel and parafilm-M substrates, which have hydrophilic, moderate and hydrophobic properties, respectively, at the Impact velocities ranging from 0.8 to 4.0 m/s. The xanthan drops spread out more widely and receded more rapidly than the glycerin drops because the spreading and receding motion drastically reduced the viscosity and consequently produced a lower level of viscous dissipation. The Impact Velocity and the liquid viscosity with shear-thinning characteristics had a dominant effect on the spreading phase. In contrast, the surface wettability had only a minor effect on the spreading phase but a very significant effect on the receding phase. The effect of the Impact Velocity on the receding phase was limited to the low-viscosity drops (with a small degree of shear-thinning) on the parafilm-M (hydrophobic) substrate. That is, when the low-viscosity drops Impacted on a hydrophobic substrate, the receding Velocity increased greatly with higher Impact Velocity, resulting in partial or complete rebound behavior. On the other hand, drop receding was significantly suppressed on the glass (hydrophilic) substrate, and the receding Velocity was almost insensitive to the Impact Velocity. Suppression of drop receding was more prominent with the liquid having a larger degree of shear-thinning characteristic (i.e., showing a larger reduction of viscosity with the increase of the shear rate).
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effects of Impact Velocity and viscosity of a shear thinning liquid droplet on spreading and receding behavior
한국액체미립화학회 학술발표논문집, 2010Co-Authors: Sang Yong LeeAbstract:In the present study, the post-impingement behavior of a shear-thinning liquid droplet on a dry surface was investigated experimentally. Four kinds of xanthan solutions were prepared and each droplet Impacted on a stainless steel plate at velocities from 0.89 to 4.01 m/s. The spreading and receding behavior of the droplets was observed and visualized using a high speed camera. A xanthan droplet with high viscosity spread slowly to reach a small maximum diameter in a short time and also receded slowly due to large and rapid viscous energy dissipation. When a droplet Impacted at high Velocity, it spread fast and reached a large maximum diameter in a short time. However, it receded more slowly with increasing Velocity even though it had larger surface energy available for receding at the larger maximum diameter. It was found that the slow receding at high Impact Velocity could be attributed to the increase of surface area affected by high shear stress, which resulted from high zero shear viscosity at the beginning of receding. Therefore, the receding process of a shear-thinning droplet could be significantly suppressed by increasing the Impact Velocity as well as the viscosity, which is desirable for spray coating and painting applications.
