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排序方式: 共有1457条查询结果,搜索用时 15 毫秒
861.
Konrad Herold Marius Böhmer Rene Savelsberg Alexander Müller Jan Schröter Jan Karthaus Un-Jae Seo Georg Jacbos Kay Hameyer Jakob Andert 《International Journal of Automotive Technology》2018,19(5):869-878
Range extender modules are one option to compensate for short drive ranges of electric vehicles. The close interaction of combustion engine and generator poses new challenges in development. A key requirement for range extender systems is to be light and virtually imperceptible in operation. High-speed electrical machines aim at increasing power density. However, their introduction in a range extender requires a gearbox. The combustion engine torque fluctuations can lead to rattle in the gearbox. The rattle can be overcome by a dual mass flywheel. An interdisciplinary model is developed and used to analyse three different range extender systems: one with a low speed generator without gearbox, one with a high-speed generator, and one with a high-speed generator and a dual mass flywheel. The efficiency was found to be higher for the system with a low speed generator, whereas the power density and the costs are beneficial for the high-speed concept. A dual mass flywheel eliminates the changes of torque direction in the gearbox. It reduces the speed fluctuations of the gearbox and generator by over 90 % compared to the low speed setup. But it increases rolling moment and subsequently chassis excitation compared to a setup with only a gearbox. 相似文献
862.
缓和曲线对交通安全的影响分析 总被引:1,自引:0,他引:1
对比分析文献表明,不合理的缓和曲线长度会影响驾驶行为和交通安全。调查分析了上三高速公路的39个弯道和2001年—2004年事故资料、沪杭高速公路浙江段的5个弯道和1999年—2004年事故资料、杭宁高速公路浙江段的6个弯道和2001年—2004年事故资料,其中缓和曲线交通事故并没有出现异常现象,表明其缓和曲线长度设计是合理的、可行的,没有对交通安全造成明显影响。在所调查的半径范围[400 m,3819.516 m],缓和曲线参数A与圆曲线半径R之比(A/R)随半径增大而呈现较好的负次幂递减规律,而且其变化范围基本上在1/3~1/2,这与传统认识及最近文献调查相一致。这一基本规律可为设计提供更明确的量化参考依据。 相似文献
863.
Based on calls for innovative ways of reducing car traffic and research indicating that car driving is often the result of habitual decision-making and choice processes, this paper reports on a field experiment designed to test a tool aimed to entice drivers to skip the habitual choice of the car and consider using—or at least trying—public transport instead. About 1,000 car drivers participated in the experiment either as experimental subjects, receiving a free one-month travelcard, or as control subjects. As predicted, the intervention had a significant impact on drivers’ use of public transport and it also neutralized the impact of car driving habits on mode choice. However, in the longer run (i.e., four months after the experiment) experimental subjects did not use public transport more than control subjects. Hence, it seems that although many car drivers choose travel mode habitually, their final choice is consistent with their informed preferences, given the current price–quality relationships of the various options. 相似文献
864.
This paper presents a study on the numerical calculation of the friction resistance coefficient of an infinitely thin plate
as a function of the Reynolds number. Seven eddy-viscosity models have been selected: the one-equation turbulence models of
Menter and Spalart–Allmaras; the k-ω two-equation model proposed by Wilcox and its TNT, BSL and SST variants and the two-equation model. The flow has been computed at 14 Reynolds numbers in sets of seven geometrically similar Cartesian grids
to allow a reliable estimation of the numerical uncertainty. The effect of the computational domain size has been reduced
to negligible levels (below the numerical uncertainty). And the same holds for the iterative and round-off errors. In the
finest grids of each set, the numerical uncertainty of the friction resistance coefficient is always below 1%. Special attention
has further been given to the solution behaviour in the laminar-to-turbulent transition region. Curve fits have been applied
to the data obtained at the 14 Reynolds numbers and the numerical friction lines are compared with four proposals from the
open literature: the 1957 ITTC line, the Schoenherr line and the lines suggested by Grigson and Katsui et al. The differences
between the numerical friction lines obtained with the seven turbulence models are smaller than the differences between the
four lines proposed in the open literature. 相似文献
865.
A. Hamish Jamson Frank C.H. Lai Oliver M.J. Carsten 《Transportation Research Part C: Emerging Technologies》2008,16(4):471-484
Forward collision warning (FCW) systems can reduce rear-end vehicle collisions. However, if the presentation of warnings is perceived as mistimed, trust in the system is diminished and drivers become less likely to respond appropriately. In this driving simulator investigation, 45 drivers experienced two FCW systems: a non-adaptive and an adaptive FCW that adjusted the timing of its alarms according to each individual driver’s reaction time. Whilst all drivers benefited in terms of improved safety from both FCW systems, non-aggressive drivers (low sensation seeking, long followers) did not display a preference to the adaptive FCW over its non-adaptive equivalent. Furthermore, there was little evidence to suggest that the non-aggressive drivers’ performance differed with either system. Benefits of the adaptive system were demonstrated for aggressive drivers (high sensation seeking, short followers). Even though both systems reduced their likelihood of a crash to a similar extent, the aggressive drivers rated each FCW more poorly than their non-aggressive contemporaries. However, this group, with their greater risk of involvement in rear-end collisions, reported a preference for the adaptive system as they found it less irritating and stress-inducing. Achieving greater acceptance and hence likely use of a real system is fundamental to good quality FCW design. 相似文献
866.
A. Goodarzi M. Naghibian D. Choodan A. Khajepour 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(12):1671-1687
Active safety systems of a vehicle normally work well on tyre–road interactions, however, these systems deteriorate in performance on low-friction road conditions. To combat this effect, an innovative idea for the yaw moment and roll dynamic control is presented in this paper. This idea was inspired by the chase and run dynamics animals like cheetahs in the nature; cheetahs have the ability to swerve while running at very high speeds. A cheetah controls its dynamics by rotating its long tail. A three-dimensional stabilizer pendulum system (3D-SPS) resembles the rotational motion of the tail of a cheetah to improve the stability and safety of a vehicle. The idea has been developed in a stand-alone 3D stabilizer pendulum system as well as in an integrated control system, which consists of an ordinary differential braking direct yaw control (DYC) and active steering control that is assisted by the 3D-SPS. The performance of the proposed 3D-SPS has been evaluated over a wide range of handling manoeuvres by using a comprehensive numerical simulation. The results show the advantage of 3D-SPS over conventional control approaches, which are ineffective on low-friction road conditions and high lateral acceleration manoeuvres. It should however be noted that the best vehicle dynamics performance is obtained when an integrated 3D-SPS and DYC and AFS is utilised. 相似文献
867.
S. H. Yoo N. T. Jeong K. S. Kim S. M. Yang J. H. Lee S. H. Choi M. W. Suh 《International Journal of Automotive Technology》2016,17(4):681-687
The use of plastic in vehicle development has increased. In particular, a design trend has resulted in chromiumplated plastics being used in exterior panels. Recently, as the appearance has become more important in design, the plastic radiator grille has become larger, to where it can become the primary member when a front collision happens. The radiator grille should be designed with considerations of the geometric structure, such as delamination, and material characteristics, when plastics are plated with chromium. The enlarged grille has to pass regulations like FMVSS Part 581. Although the material property of plastic has been studied before, what seems to be lacking is study on the crashworthiness of plastic radiator grilles that are plated using chromium. In this paper, in order to evaluate the crashworthiness, tensile test and front collision analysis using finite element method are performed. Tensile test is conducted with 4 types of materials, and then material properties of chromium-plated plastics are obtained. Meanwhile radiator grille’s crashworthiness is evaluated using finite element analysis method. Analysis result is evaluated according to failure criterion. Through this study, method of the assessment of plastic radiator grille’s crashworthiness considered material properties of chromium plated plastics is proposed, and it can be predicted the delamination and the failure point of radiator grille at the design step. 相似文献
868.
This study proposes a design for an idle speed controller to compensate for varying engine load and friction torque in passenger car diesel engines. An active disturbance rejection control (ADRC) framework, comprised of a disturbance compensator and a feedback controller, is applied to an idle speed controller to compensate for disturbances such as engine load and friction torque. In addition, a feedforward compensator is designed into the ADRC framework to improve disturbance rejection performance. The proposed controller is validated by engine and vehicle experiments and the experiment results are compared with a commercial controller. 相似文献
869.
J. M. Kim K. M. Kim S. J. Ha M. S. Kim 《International Journal of Automotive Technology》2016,17(6):967-976
Grille opening shape for small passenger car is designed numerically by using parametric study. Key geometric parameters to design a grille opening configuration are represented by vertical height, horizontal width, size, linear deformation, position, and blockage. Numerical study investigates the effects of those key parameters on the aerodynamic drag and the grille inlet flow rate, which are very important to the aerodynamic performance as well as the powertrain cooling performance of the car. Flow simulations are performed at the velocity of 110 km/h inflow condition. The outflow boundary condition is implemented by pressure outlet condition of atmospheric pressure. Moving wall condition of 110 km/h is set on the ground. 相似文献
870.
Steer-by-wire (SBW) system which is characterized by variable steering feel, better active safety, unmanned drive, has been widely studied to realize a distinctive driving experience. Control strategy acts as a key part of SBW system to achieve the goals. In this paper, a control strategy by bilateral control structure for steer-by-wire system is proposed. To make SBW system has the same function of conventional steering systems, the controller is designed to realize desired tracking control and realistic road feel feedback. The control of position and torque for each actuator is taken as two ports for the control network. Based on different control loop, two kinds of bilateral control is investigated respectively. The hardwarein- the-loop experiment platform of SBW is developed by the reconfiguration of electric power steering system. The test results are compared to show the performance of different control loops. 相似文献