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571.
The circulation system of a slurry shield is composed of a transportation system and a processing system.For shield construction, correct selection of the circulation system for the slurry shield is directly related to construc-tion speed. Using the Nanjing Yangtze tunnel as an example, the material balance calculation of the circulation sys-tem, sieving effect analysis, and analysis of the muck carrying ability of the dredging pipe are conducted for various strata. The practical results show that above mentioned calculations and analysis method provide a good reference for the proper selection of a slurry separation system and dredge pipe. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
572.
573.
S.?Oikawa Y.?MatsuiEmail author T.?Sakurai 《International Journal of Automotive Technology》2014,15(7):1129-1136
The vehicle travel velocity at pedestrian contact is considered to be an important parameter that affects the crash outcome. To reduce vehicle/pedestrian impact velocity, a collision damage mitigation braking system (CDMBS) using a sensor for pedestrian protection could be an effective countermeasure. The first purpose of this study is to clarify the relation between vehicle travel velocity and pedestrian injury severity due to differences in pedestrians’ ages in actual traffic accidents. The accident analyses were performed using vehicle-pedestrian accident data in 2009 from the database of the Institute for Traffic Accident Research and Data Analysis (ITARDA) in Japan. The result revealed that the fatality risk became higher with the increase in vehicle travel velocity. The second purpose of this study is to determine the safety performance of production vehicles equipped with the CDMBS for pedestrian protection. It was found that the CDMBS was highly effective in reducing the impact velocity from 50 km/h (vehicle travel velocity) to below 17 km/h, that could result in a significant decrease in fatality risk to be 2% or less. Additionally, the authors investigated a detectable zone with respect to a pedestrian’s position in relation to the vehicle. It was shown that the detectable zones for production vehicles tested were limited to be inside the vehicle front width. 相似文献
574.
Y. Shi I.- T. Lee A. Md. Afsar J.- I. Song 《International Journal of Automotive Technology》2009,10(4):481-488
As the number of disabled people grows, independence and mobility become a priority for those individuals. To achieve this
goal, a ‘Turny-type power seat’ was developed in this study to assist a disabled person rise from a vehicle without trouble.
The design and modeling of the power seat were performed using AutoCAD and CATIA software. The major motions of the power
seat system are swiveling, sliding, and extending, which are accomplished primarily by DC motors, chains, and gears. Most
of the power seat parts were made from mild steel. Welding technology was used throughout the frame fabrication. To ensure
the safety and stability of the power seat, various tests were performed, and the results analyzed. The static analysis of
the power seat was carried out by ANSYS 11.0. The results showed that the power seat conformed to the Americans with Disabilities
Act (ADA) standards. The durability test was performed by repeatedly rotating and sliding the power seat under loading conditions.
Dynamic crash simulation was carried out using the LS-DYNA software. The durability test ensured a longer life of the power
seat, while the crash analysis showed a small rotational distortion that was not harmful to passengers. However, the front
seat had a slightly larger forward displacement, which was not comfortable for passengers. Therefore, further modifications
of the power seat should be done to improve the performance, with attention given to the reduction of the forward displacement
in the event of a crash. 相似文献
575.
Domestic automobile insurance claims were investigated to correlate the driver neck injury risk with the safety rating of
the head restraint, the severity of vehicle damage, and other human factors. The results of our statistical analysis reveal
that the risk of neck injury for the driver is significantly different for vehicle size, use, driver gender, driver age, impact
direction, accident location, and safety rating of head restraint, depending on vehicle the damage level which is assumed
to imply impact severity during a rear-end crash accident. One of the unique findings from domestic insurance claims from
low-speed rear-end crash accidents is the frequent reports of lower back injury together with whiplash. Thus, the risk of
lower back discomfort is also included in this statistical analysis. 相似文献
576.
The purpose of this study is to understand the operational characteristics of a diesel engine that uses BD20 reformed by ultrasonic
energy irradiation. In particular we study the effects of tuning injection delay and EGR rate. BD containing about 10% oxygen
has attracted attention due to soaring crude oil prices and environmental pollution. This oxygen decreases soot by promoting
combustion, but it also increases NOx. To solve this problem, injection timing may be delayed or an EGR system may be applied.
These adjustments normally lower engine power and increase exhaust emission but, in using fuel reformed by ultrasonic energy
irradiation (which is changed physically and chemically to promote combustion), we may hope to circumvent this problem. To
control the duration of the ultrasonic energy irradiation, the capacity of the chamber in an ultrasonic energy fuel supply
system was tested at 550cc and 1100cc capacities. As for the results of the experiment, we could identify the optimum EGR
rate by investigating the engine performance and the characteristics of exhaust emissions according to the injection timing
and the EGR rate while ultrasonically irradiated BD20 was fed to a commercial diesel engine. With UBD20 (at an injection timing
of BTDC 16°), the optimum EGR rate, giving satisfactory engine performance and exhaust emissions characteristics, was in the
range of 15∼20%. 相似文献
577.
黄冈公铁两用长江大桥桥塔为H形钢筋混凝土结构,塔高190.5m,采用液压爬模法施工。为满足液压爬模在高塔施工过程中快速化施工的需求并确保施工安全,针对桥塔结构特点,选用将5m节段液压爬模改进成6m的节段液压爬模进行桥塔施工,并对液压爬模结构进行优化改进,包括整体制作大装饰槽和大倒角模板并固定在液压爬模上,在大装饰槽处附墙装置下增加牛腿,将塔柱内、外侧面液压爬模上支架后移平台加长50cm。通过合理布置桥塔液压爬模轨迹,桥塔液压爬模只在中下塔柱转角处进行1次转换,避免了液压爬模在高空中多次转换的风险;液压爬模采用分组整体转换,加快了桥塔施工速度。实践证明,该桥采用液压爬模施工技术,实现了高效快速化施工目标,且施工过程安全。 相似文献
578.
H. Liu G.N Liu K J Huo T Liu X H Zhang K Liu K Tao Y. J. Liu . Mechanical Engineering School Xi''''an Jiaotong University Xi''''an China . Strength Centre Zhengzhou Research Institute of Mechanical Engineering Zhengzhou China . Fo 《上海交通大学学报(英文版)》2000,(1)
IntroductionThefiwtee1emenmethod(FEM)playsanextrmelyimPortantroleintheanalysesofengineeringproblems.ForalongtimethismethodhasmainlybeenaPPliedinthelinearfieldandshownitsgreatpower.HoweveealOtofnonlinearengineeringPrOblemsWhichcanneitherbesimPlyreducedtolinearonesnorrCPresentedbylinearlyanalogywhichshallchnsethePfacticalconditionsrelativelymuch,havechallengedfiniteelementmethod(FEM).RecentymuchProgresshasbeenmadebothinthemathematicalandmechanicaltheoryandthecomPulertechnologysothatevent… 相似文献
579.
Vertical Load-Deflection Behaviour of a Pneumatic Tire Subjected to Slip and Camber Angles 总被引:1,自引:0,他引:1
Y.Q. Wang Dr.-lng R. Gnadler Professor Dr.-Ing R. Schieschke Dr.-lng. Ingenieurgemeinschaft Prof. Dr.-Ing 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1996,25(2):137-146
In this paper the vertical load-deflection behaviour of a pneumatic tire has been studied theoretically. A simple mathematical model which is especially suitable for a tire applied by a side force has been developed. Researches carried out in the past show that the tire vertical stiffness varies neither proportionally nor symmetrically as the slip angle of a cambered tire is changed. This effect can be explained by the theory developed here.
The model predictions have been verified using experimental results obtained from literature. Moreover, tire cornering characteristic curves obtained under different test conditions, i. e. during increasing of the slip angle the vertical load is kept constant or not, have been discussed through a simulation example. This study shows that the characteristic curves vary rather considerably under the different conditions. 相似文献
The model predictions have been verified using experimental results obtained from literature. Moreover, tire cornering characteristic curves obtained under different test conditions, i. e. during increasing of the slip angle the vertical load is kept constant or not, have been discussed through a simulation example. This study shows that the characteristic curves vary rather considerably under the different conditions. 相似文献
580.
分析了铁路沿线居民对噪声的反应,并比较了铁路与交通运输噪声主观反应。结果表明,无论是高干扰率阈值的比较,或是从高干拢率与声级的回归方程比较,铁路和交通这两种运输噪声对人的主观反应干扰基本一样。 相似文献