Current Issue : April - June Volume : 2012 Issue Number : 2 Articles : 5 Articles
A reliable and efficient highway broadcast model based on gain prediction is proposed to solve excessive information\r\nretransmission and channel conflict that often happen to flooding broadcast in vehicular ad hoc network. We take accountof the\r\nrelative speeds, the intervehicle distance, and the coverage difference of the neighboring vehicles into predicting the gain of every\r\nneighbor, and further select the neighbor with the maximum gain as the next hop on the every direction of road. Simulations show\r\nthat the proposed model is clearly superior to the original flooding model and a recent variant based on mobility prediction in\r\npacket arrival rate, average delay, forwarding count, and throughput....
An energy conservation algorithm for numerically solving nonlinear multidegree-of-freedom\nMDOF dynamic equations is proposed. Firstly, by Taylor expansion and Duhamel integration,\nan integral iteration formula for numerically solving the nonlinear problems can be achieved.\nHowever, this formula still includes a parameter that is to be determined. Secondly, through\nsome mathematical manipulations, the original dynamical equation can be further converted into\nan energy conservation equation which can then be used to determine the unknown parameter.\nFinally, an accurate numerical result for the nonlinear problem is achieved by substituting this\nparameter into the integral iteration formula. Several examples are used to compare the current\nmethod with the well-known Runge-Kutta method. They all show that the energy conservation\nalgorithm introduced in this study can eliminate algorithm damping inherent in the Runge-Kutta\nalgorithm and also has better stability for large integral steps....
The ongoing controversy about in what condition should we set the curb parking has few definitive\r\nanswers because comprehensive research in this area has been lacking. Our goal is to present a set\r\nof heuristic urban street speed functions under mixed traffic flow by taking into account impacts\r\nof curb parking. Two impacts have been defined to classify and quantify the phenomena of motor\r\nvehicles� speed dynamics in terms of curb parking. The first impact is called Space impact, which\r\nis caused by the curb parking types. The other one is the Time impact, which results from the\r\ndriver maneuvering in or out of parking space. In this paper, based on the empirical data collected\r\nfrom six typical urban streets in Nanjing, China, two models have been proposed to describe these\r\nphenomena for one-way traffic and two-way traffic, respectively. An intensive experiment has\r\nbeen conducted in order to calibrate and validate these proposed models, by taking into account\r\nthe complexity of the model parameters. We also provide guidelines in terms of how to cluster\r\nand calculate those models� parameters. Results from these models demonstrated promising\r\nperformance of modeling motor vehicles� speed for mixed traffic flow under the influence of curb\r\nparking....
There is no literature mentioning the electromechanical behavior of micro\r\nstructures driven by traveling electrostatic forces. This article is thus the first to present the\r\ndynamics and stabilities of a micro-ring subjected to a traveling electrostatic force. The\r\ntraveling electrostatic force may be induced by sequentially actuated electrodes which are\r\narranged around the flexible micro-ring. The analysis is based on a linearized distributed\r\nmodel considering the electromechanical coupling effects between electrostatic force and\r\nstructure. The micro-ring will resonate when the traveling speeds of the electrostatic force\r\napproach some critical speeds. The critical speeds are equal to the ratio of the natural\r\nfrequencies to the wave number of the correlative natural mode of the ring. Apart from\r\nresonance, the ring may be unstable at some unstable traveling speeds. The unstable\r\nregions appear not only near the critical speeds, but also near some fractions of some\r\ncritical speeds differences. Furthermore the unstable regions expand with increasing\r\ndriving voltage. This article may lead to a new research branch on electrostatic-driven\r\nmicro devices....
The travel time of left-turning vehicles at signalized intersection was discussed. Under the\r\nassumption that the opposing through vehicles headway follows M3 distribution, the travel time\r\nmodel was established on the basis of gap theory and queue theory. Comparison was done with\r\nthe common model based on the assumption that the opposing through vehicles headway follows\r\nnegative exponential distribution. The results show that the model in this paper has stronger\r\napplicability and its most relative error is less than 15%. In addition, the sensitivity analysis was\r\ndone. The results show that the opposing through flow rate has significant impact on travel time.\r\nThe impact of left-turning flow rate and following headway is light when the opposing through\r\nflow rate is small, the threshold is about 0.18 veh/s. The model established in this paper can well\r\ncalculate travel time of left-turning vehicles at intersection, and the methodology may provide\r\nreference to other occasions....
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