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991.
992.
L. H. Zhao S. L. Zheng J. Z. Feng H. F. Zhou Y. F. Xing 《International Journal of Automotive Technology》2014,15(5):843-852
Accurately predicting the fatigue life is the basis for the reliability and lightweight design of automobile parts. However, the predicted lives under service loadings on the basis of the S-N curve from constant amplitude loads from existing methods often seems conservative compared with real lives, because of ignoring the strengthening effect of loads below fatigue limit. In this paper, a fatigue damage model, which is modification of Miner’s Rule, was established for the fatigue assessment under service loadings by means of taking into account the strengthening and damaging effects of loads below fatigue limit. Then this model and conventional Miner’s Rule are applied to the estimate the fatigue life of a torsion beam rear axle using the loading history recorded on proving ground. Finally, verification tests are performed on MTS road load simulator test bed. Results of predicted lives and fatigue tests demonstrate that the accuracy of the predicted life could be greatly improved by taking into account the strengthening and damaging effect of loads below fatigue limit. 相似文献
993.
Free piston engine generators which utilize a free piston engine and a linear generator are under investigation by a number of research groups around the world. Free piston engines give power output in a more efficient way when compared to conventional crankshaft engines, because the former do not have a crank mechanism which brings about additional mechanical loss. However, for the reliable and stable operation of the free piston engine generators, it is required to have a viable control system to address the uncertainty of piston motion. In this paper, most of the successful free piston engine generator developments were reviewed and a recent experimental result on a prototype free piston system was also presented with regard to engine performance with different mixture preparation strategies. 相似文献
994.
提出了一种通用的现场总线协议架构——层次代理总线架构(HABA,Hierarchical Agent Bus Architecture),能够承载多种异构的总线类型,并实现高效互联互通。基于此架构,设计了融合485总线、电力线载波总线、Ethernet等多种总线类型的综合能效管理系统,并通过现场实施的分析数据,验证了HABA能够保证并提高网络利用率以及数据采集的稳定性和实时性。 相似文献
995.
996.
Building on earlier work to incorporate real option methodologies into network modeling, two models are proposed. The first is the network option design problem, which maximizes the expanded net present value of a network investment as a function of network design variables with the option to defer the committed design investment. The problem is shown to be a generalized version of the network design problem and the multi-period network design problem. A heuristic based on radial basis functions is used to solve the problem for continuous link expansion with congestion effects. The second model is a link investment deferral option set, which decomposes the network investment deferral option into individual, interacting link or project investments. This model is a project selection problem under uncertainty, where each link or project can be deferred such that the expanded net present value is maximized. The option is defined in such a way that a lower bound can be solved using an exact method based on multi-option least squares Monte Carlo simulation. Numerical tests are conducted with the classical Sioux Falls network and compared to earlier published results. 相似文献
997.
Jiancheng Long Ziyou Gao W.Y. Szeto 《Transportation Research Part B: Methodological》2011,45(1):232-254
In the research area of dynamic traffic assignment, link travel times can be derived from link cumulative inflow and outflow curves which are generated by dynamic network loading. In this paper, the profiles of cumulative flows are piecewise linearized. Both the step function (SF) and linear interpolation (LI) are used to approximate cumulative flows over time. New formulations of the SF-type and LI-type link travel time models are developed. We prove that these two types of link travel time models ensure first-in-first-out (FIFO) and continuity of travel times with respect to flows, and have other desirable properties. Since the LI-type link travel time model does not satisfy the causality property, a modified LI-type (MLI-type) link travel time model is proposed in this paper. We prove that the MLI-type link travel time model ensures causality, strong FIFO and travel time continuity, and that the MLI-type link travel time function is strictly monotone under the condition that the travel time of each vehicle on a link is greater than the free flow travel time on that link. Numerical examples are set up to illustrate the properties and accuracy of the three models. 相似文献
998.
EEDI(船舶能效设计指数)是衡量船舶在航行中CO2排放量的考核指标。依据MEPC.59提出的EEDI临时指导公式分析了EEDI对主机选型的影响。以230000DWT矿砂船为例,在核算的EEDI与基线差别不大情况下,通过适当降低航速来降低主机安装功率以满足EEDI基线的要求,从而验证了该方法的的有效性。探讨了未来应对EEDI的其它方法。 相似文献
999.
ManWo Ng W.Y. SzetoS. Travis Waller 《Transportation Research Part B: Methodological》2011,45(6):852-866
An assumption that pervades the current transportation system reliability assessment literature is that probability distributions of the sources of uncertainty are known explicitly. However, this distribution may be unavailable (inaccurate) in reality as we may have no (insufficient) data to calibrate the distribution. In this paper we relax this assumption and present a new method to assess travel time reliability that is distribution-free in the sense that the methodology only requires that the first N moments (where N is a user-specified positive integer) of the travel time to be known and that the travel times reside in a set of bounded and known intervals. Because of our modeling approach, all sources of uncertainty are automatically accounted for, as long as they are statistically independent. Instead of deriving exact probabilities on travel times exceeding certain thresholds via computationally intensive methods, we develop semi-analytical probability inequalities to quickly (i.e. within a fraction of a second) obtain upper bounds on the desired probability. Numerical experiments suggest that the inclusion of higher order moments can potentially significantly improve the bounds. The case study also demonstrates that the derived bounds are nontrivial for a large range of travel time values. 相似文献
1000.