基于旅客-车体耦合振动的车辆振动分析

利用实验方法研究了旅客对车体振动特性的影响,建立了旅客-车体耦合振动分析模型,针对旅客人数及旅客分布对车体振动的影响,进行了仿真分析。     

Adaptive Control of 4WS System by Using Neural Network

An adaptive control system of the model following type is proposed for drive motion control of a four wheel steering (4WS) car with using neural network (NN) which has mastered nonlinear friction force between tire and road surface. A model of one rigid body is adopted which represents appropriately two kinds of car motion caused by steering action, namely the lateral displacement and the yawing rotation, and an equation of motion is described in a simplified form to make a system equation for motion control possible. Nonlinear relation between the cornering force of tire and the slip angle is obtained by numerical analysis with the tire model proposed by E. Fiala, taking friction coefficient and car speed as the parameters. The result is used as the teaching signal for NN. Three NN are used in the control system composed of both the feed-forward and the feedback circuits in order to realize adaptive control. Validity and usefulness of the proposed adaptive control system with NN are verified by three kinds of computer simulation.     

Rationale for utilizing 3PL in supply chain management: A shippers' economic perspective

In this paper we first propose a conceptual framework for evaluating 3PL (third-party logistics) utilization in SCM (supply chain management), in which it is assumed that shippers may enjoy advantages derived from four contributory sources of 3PL specialization: scale, know-how, searching ability, and IT skills. It is also supposed that shippers may particularly benefit from 3PL when facing uncertain business environments. We also apply principal–agent relationships to shippers and 3PL providers. Further, we see enhancing “agency efficiency” as important to obtaining the benefits of 3PL utilization. We also look at the role of 3PL provider selection, the “hold-up” problem under incomplete contracts, and asset ownership. After that we briefly discuss the utilization of 3PL and environmental concerns. These are the main points that we consider related to 3PL utilization. The main contribution of this study is to identify discussion points from models and theories, such as contract theory, that relate to the utilization of 3PL in SCM.