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81.
82.
Planning of sustainable transportation systems requires integration of multiple systems while considering a holistic approach. A limited amount of research has been conducted that simultaneously considers all the transportation, economic activity, environmental and social effects. The proposed research envisages incorporating considerations related to sustainability and providing solutions to stakeholders in policy making. In this paper, a dynamic model for planning and development of sustainable transportation systems is presented. This is given by a system of three nonlinear differential equations representing the dynamics of the three independent states, namely, transportation, activity, and environmental systems. A policy scenario considering investment in energy efficient technologies and its effects on the states is discussed to assist making investment decisions. Optimal control techniques are used to design the controls. The results show that it is possible to formulate an optimal control to achieve the desired target. Numerical results, based on actual parameters, are presented to illustrate the long-term trends of the states. The methodology discussed in this paper will be helpful to decision makers in making optimal decisions. The contribution of this research work is the introduction of a systems and controls methodology to develop optimal policies for the design of sustainable systems. 相似文献
83.
王慈光 《西南交通大学学报》1996,31(4):426-432
本文引进面的度数这一概念,给出作为哈密尔顿图的必要条件的伴随定理,提出一个在给定的连通平面图上找哈密尔顿回路的方法-图的吸收变换法。 相似文献
84.
采用整体迭代法,研究n维Klein-Gordon方程Cauahy问题的渐近理论。在Sobolev空间中,证明了初值问题的适定性和形式近似解的合理性在长时间t∈[0,T(ε))内成立,其中ε是小参数. 相似文献
85.
应用功率键合国理论,对液压铆钉机进行了计算机动态数字仿真,使得在设计阶段即可根据模拟物理模型,预测其动态性能。这种方法可推广到任何一个需要重新设计的非标准设备,从而大大提高设计效率并保证设计质量。 相似文献
86.
孙秋杰 《石家庄铁道学院学报》2006,19(3):106-107,111
通过多重集排列计数,给出点标号完全三部图Kn,n,n的Ham ilton圈数hn计数公式3[n/2]hn=(n!)n∑2。k=02n-2k-1n-1n-1k 相似文献
87.
迟作江 《大连铁道学院学报》1991,12(3):46-50
本文从数学推演、力学系统运动的初值问题的提法和变分原理的基本要求这三个方面论述了 Hamilton 变分原理不适用于非完整力学系统。 相似文献
88.
Kenneth Button 《运输规划与技术》2016,39(2):136-161
The paper sets in context some of the more recent work that has been conducted on public–private partnerships (PPPs) in the provision and operation of infrastructure. PPPs essentially involve a government or its agent signing an agreement with a private company or consortium to supply it with services with the private sector actor involved in major elements of designing, building, temporarily ‘owning’, and running the physical assets; basically they are long-term development and service contracts between government and a private partner. The paper outlines the development of economic thinking regarding the rationale behind PPPs, the extent to which unbundling is optimal and the forms that it may take, the nature of the contracts that are enacted and their renegotiation, the awarding of contracts, and matters of possible corruption. By way of focus, it also provides some indication of what empirical studies in the transportation have thrown up regarding the outcomes of PPPs. 相似文献
89.
90.
L. Xin V.L. Markine I.Y. Shevtsov 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(3):301-327
A three-dimensional (3-D) explicit dynamic finite element (FE) model is developed to simulate the impact of the wheel on the crossing nose. The model consists of a wheel set moving over the turnout crossing. Realistic wheel, wing rail and crossing geometries have been used in the model. Using this model the dynamic responses of the system such as the contact forces between the wheel and the crossing, crossing nose displacements and accelerations, stresses in rail material as well as in sleepers and ballast can be obtained. Detailed analysis of the wheel set and crossing interaction using the local contact stress state in the rail is possible as well, which provides a good basis for prediction of the long-term behaviour of the crossing (fatigue analysis). In order to tune and validate the FE model field measurements conducted on several turnouts in the railway network in the Netherlands are used here. The parametric study including variations of the crossing nose geometries performed here demonstrates the capabilities of the developed model. The results of the validation and parametric study are presented and discussed. 相似文献