Xing Jianping

Application of Dynamic Traffic Flow Map by Using Real Time GPS Data Equipped Vehicles

Dynamic traffic flow map is one of the focuses of recent researches on ITS, but it is limited by the locations and numbers of traffic detectors. This paper presents a method for traffic flow map using the data received from the GPS mobile terminals equipped vehicles. Firstly, a vehicle real-time monitoring GPS system is given. Secondly, a map-matching method was proposed, which eliminated ineffective data by observing the vehicles status and calculated link time cost of each probe vehicle and the average speed. The equation of speed-flow relationship established by observing traffic data, especially the general one established in conditions of any traffic roads under any traffic burden conditions. Thirdly, it developed a dynamic traffic flow map arithmetic based on the results above and successfully solved the questions: data collecting, traffic barrier-free conditions processing and traffic flow map calculating. Finally, the results of simulation experiment indicate that the methods are effective and practical. It can be used as a new real time network method to control the traffic signal, which is different from the traffic signal controlled method that depends on the timer or road linear controller method

The Research of a New Workflow Model with Step-Task Layers Based on XML Documents

The research of workflow technology has been an active area for many years. Modeling of workflow is arguably the most important issue. In this paper, a workflow model with two layers named as S-T workflow model is created which is based on directed cyclic graph. We separate control node and task node in two layers. Step layer describes process control logic and task layer parallels concrete affairs to make the workflow clear. We address the modeling strategy at first, and then depict the features of S-T workflow model in detail, and propose arithmetic to verify the soundness of modeling structure. Besides, the parsing process of documents, and the design format of documents are also given in this paper

Powder Sputtered SnO2, ZnO Thin Film Gas Sensors

Powder sputtering method has the advantage of doping impurity stability. Some performances of SnO2, ZnO gas sensing thin film and the idea of designing gas sensor are introduced. The processing, techniques, chip structure and performance about two kinds of thin film gas sensors are given out. Simultaneously, we got two conclusions: the first one, metal oxide thin film sensor obtained by the powder sputtering method is likely to become popular goods in the field of gas sensors; the other one, ZnO thin film is another gas sensor basic material besides SnO2 that can be studied and developed. The key for ZnO thin film sensor is to choose the suitable substrate

Analysis of OSSDL and IVCN self-localization algorithms in wireless sensor networks

A range-free three dimensional localization scheme based on optimum space step distance (OSSDL) and an improved node self-localization algorithm based on virtual central node (IVCN) for wireless sensor network (WSN) are proposed in our previous papers. By analyzing classic two dimensional DV-Hop localization algorithm, OSSDL algorithm realizes localization. Especially by optimizing distances from the 3D network model, the optimum space step distance from nodes to anchors in OSSDL is obtained and the coordinates of all unknown nodes can be derived finally. However in IVCN localization algorithm, by deducing a 3D special node in the cube which is virtually formed by eight anchor nodes, which is called virtual central node, unknown nodes can compute their own estimated positions automatically. In this paper, a comprehensive analysis of OSSDL and IVCN are presented to explore their true performances. We also have made comparisons with classic DV-Hop and Centroid algorithms with several parameters changed under the same simulation environments. The index of positioning accuracy is addressed. From simulation results, IVCN performs better on localization accuracy than OSSDL, which is definitely much better than that of original DV-Hop.

Performance analysis of VCN and CFOSSDL localization algorithms in wireless sensor networks

A node self-localization algorithm based on virtual central node (VCN) and another CF_OSSDL method which stems from classic DV-Hop propagation algorithm are proposed respectively in our papers before. In this paper comprehensive analysis of the two algorithms are listed. In VCN algorithm, by deducing a 3D special node, which is called the virtual central node, unknown nodes can compute their own positions automatically. Differently in CF_OSSDL algorithm, by computing optimum space step distance between unknown nodes and anchor nodes in which sole correction factor of each unknown node is added (CF_OSSDL), all nodes with no position coordinates can realize self-localizing. The localization mechanism has been implemented in Matlab simulation software. Simulating experiments are made to explore the two range-free localization algorithms. The effectiveness and robustness of algorithms are clearly demonstrated through extensive simulation results.

Thermal-Power Consumption and Heat Transfer Coefficients in Micro-thin-film Gas Sensors

The thermal-power consumption is a important parameter of gas sensor. The temperature distribution of thin film gas sensor, temperature of metal guard, the dissipating heat of lead-wires and the regularity of sensors heat transfer coefficient varying with size of heat-transfer surface and working temperature was studied. The formula of thermal-power consumption of micro-thin-film gas sensors yielded in this paper, from which, the calculation results consisted with the experiment. Finally, some related problems were discussed

Experiment and Theory for the Thickness Effect of Nano Metal Oxide Gas Sensing Thin Film Dynamic Thickness Effect and Theory of Diffusion Reaction

The rule of characteristic time varies with film thickness, gas concentration is given by experiment results. The diffusion reaction model of conductance response for porous gas sensing thin film is proposed; with solution and non-dimensional analyze the reaction diffusion equation, the rule of character time can be yielded. Using the method of combination of theoretical and experimental, the surface adsorption exponent gamma and adsorbing energy Ea are discussed

Experiment and Theory for the Thickness Effect of Nano Metal Oxide Gas Sensing Thin Film The Thickness Effect and Mesoscopic Theory of Conductance Activity Energy

The characteristics of conductance activity energy of SnO2 thin film varies with film thickness l and grain size r0 are given by experiment results. The cross-section current formula of porous materials and the conductance formula of gas sensing thin film with adsorbed oxygen negative ion are given. The mesoscopic theory of nano-thin film conductance activity energy was proposed, and using the corrected Fermi statistic formula for the concentration of adsorbed negative ion, the theoretical curve of Eact varies with grain size r0 yield; from which, the related problems are discussed.

Experiment and Theory for the Thickness Effect of Nano Metal Oxide Gas Sensing Thin Film Optimum Size of Crystal Grains and Theory of Mesoscopic Effect

For pt. I see ibid., p.Z001463-8, (2006). The existence of the optimum film thickness and optimum grain size of nano metal oxide gas sensing thin films is given by experiment results. The existence of the optimum grain size is examined theoretically to be a new mesoscopic effect, resulting from the failure of Fermi statistic law of the adsorbed negative oxygen ion concentration when the grain size reduces to a certain range. According to Kubos theory that as the grain size reduces to a characteristic length rm the grain would be neutrality, Fermi statistics is modified, and therefore, the theoretical result of the optimum grain size r0*=2rm is yielded. With the Kubos formula of electron work function, the values of rm and r0* can be estimated, which consist with the experimental results