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881.
882.
Joan L. Walker Emily EhlersIpsita Banerjee Elenna R. Dugundji 《Transportation Research Part A: Policy and Practice》2011,45(4):362-374
While psychologists and behavioral economists emphasize the importance of social influences, an outstanding issue is how to capture such influences in behavioral models used to inform urban planning and policy. In this paper we focus on operational models that do not require explicit knowledge of the individual networks of decision makers. We employ a field effect variable to capture social influences, which is calculated as the percent of population in the peer group that has chosen the specific alternative. We define the peer group based on socio-economic status and spatial proximity of residential location. As in behavioral economics and psychology, the concept is that one is influenced by the choices made by one’s peers. However, using such a social influence variable in a behavioral model causes complications because it is likely endogenous; unobserved factors that impact the peer group also influence the decision maker, yielding correlation between the field effect variable and the error. The contribution of this paper is the use of the Berry, Levinsohn, and Pakes (BLP) method to correct the endogeneity in a choice model. The two-stage BLP introduces constants for each peer group to remove the endogeneity from the choice model (where it is difficult to deal with) and insert it into a linear regression model (where endogeneity is relatively easier to deal with). We test the method using a mode choice data set from the Netherlands and readily available software and find there is an upward bias of the field effect parameter when endogeneity is not corrected. The procedure outlined presents a practical and tractable method for incorporating social influences in choice models. 相似文献
883.
层间水对水下双层结构撞击历程的影响分析 总被引:1,自引:1,他引:0
双层壳体结构是潜艇等大型水下结构的重要结构形式,潜艇结构的水下碰撞是潜艇的主要事故形式,然而,针对双层壳体的潜艇结构水下碰撞问题的研究工作目前却极为有限.文中首先提出潜艇碰撞问题,并对其碰撞特征进行分析,然后针对潜艇水下碰撞环境下,层间水对碰撞历程的影响和双层结构的碰撞特点进行了理论分析,在数值仿真计算的基础上,着重讨论了双层板结构在碰撞过程中,层间水对撞击速度、碰撞力以及双层板吸能特性的影响,分析结果显示,层间水对双层壳板撞击历程的影响主要体现在两方面:一是接触初始阶段,耐压壳板将由于层间水的存在,与非耐压壳板组成抗冲击弹簧体系参与抗冲击作用,吸收冲击能量,这对于双层壳板的防撞性能是有利的;二是非耐压壳板穿透后,层间水的影响主要体现为水对耐压壳板的粘附作用,耐压壳板的抗撞能力显著下降. 相似文献
884.
885.
886.
887.
If a driver passes over a pedestrian lying on the road and flees, it is considered a crime. In several cases, even if the
driver fled and was arrested, he/she often asserts that they did not know that the victim was a human being. However, the
investigation agency often believes that a driver can certainly recognize when he/she passes over a person. Accordingly, such
cases frequently lead to disputes due to the lack of criteria for recognizing when a driver was involved in run-over accidents.
In this study, tests were conducted both to identify if drivers can recognize whether their vehicles passed over a person
and to examine how they feel at the time. A silicon dummy, which was manufactured to have the same characteristic as the human
chest, was used in this study. According to the method specified in ISO2631, the vibration delivered to the driver was measured,
and eighteen participants drove a vehicle over the silicon dummy to experience how the vibrations felt. When the passenger
car for the test ran over the dummy at speeds ranging from 10 km/h to 60 km/h, all participants recognized the delivered vibration,
and the VDV that was delivered to the participants ranged from 1.81 m/s
1.75 to 2.38 m/s
1.75. The participants thought that the object they drove over was a stone or a piece of wood. This indicates that the driver
certainly can recognize the vibrations generated from passing over a human chest even though it feels like a solid object. 相似文献
888.
889.
H.?-Z.?Li L.?LiEmail author L.?He M.?-X.?Kang J.?Song L.?-Y.?Yu C.?Wu 《International Journal of Automotive Technology》2012,13(3):441-450
A Traction Control System (TCS) is used to control the driving force of an engine to prevent excessive slip when a vehicle
starts suddenly or accelerates. The torque control strategy determines the driving performance of the vehicle under various
drive-slip conditions. This paper presents a new torque control method for various drive-slip conditions involving abrupt
changes in the road friction. This method is based on a PID plus fuzzy logic controller for driving torque regulation, which
consists of a PID controller and a fuzzy logic controller. The PID controller is the fundamental component that calculates
the elementary torque for traction control. In addition, the fuzzy logic controller is the compensating component that compensates
for the abrupt change in the road friction. The simulation results and the experimental vehicle tests have validated that
the proposed controller is effective and robust. Compared with conventional PID controllers, the driving performance under
the proposed controller is greatly improved. 相似文献
890.
The intake system in an automotive engine has a short duct compared with that of the exhaust system. The filtered-x LMS (FX-LMS)
algorithm has been applied to the active noise control (ANC) system in a short acoustic duct. This algorithm design is based
on the FIR (finite impulse response) filter; however, it has a slow convergence issue due to a large number of zero coefficients.
To improve the convergence performance, the step size of the LMS algorithm was modified from fixed to variable. However, this
algorithm is still not suitable for the ANC system of a short acoustic duct because the reference signal is affected by the
backward acoustic wave propagated from a secondary source. Therefore, the recursive filtered-u LMS algorithm (FU-LMS) based
on the infinite impulse response (IIR) is developed to consider backward acoustic propagation. Generally, this algorithm has
a stability problem. The stability issue was improved using an error-smoothing filter. In this paper, the recursive LMS algorithm
with a variable step size and smoothing error filter is designed. This recursive LMS algorithm, the FU-VSSLMS algorithm, uses
an IIR filter. With fast convergence and good stability, this algorithm is suitable for the ANC system in a short acoustic
duct, such as the intake system of an automotive engine. This algorithm is applied to the ANC system of a short acoustic duct.
The disturbance signals used as primary noise source are a sinusoidal signal embedded in white noise and the chirp signal,
which has a variable instantaneous frequency. The test results demonstrate that the FU-VSSLMS algorithm has a superior convergence
performance when compared with the FX-LMS and FX-LMS algorithms. The algorithm can be successfully applied to the ANC system
in a short duct, such as the intake duct. 相似文献