Advanced Materials Research Vols. 291-294

Abstract: Timed Petri net (TPN) has been utilized as a visual formalism for the modeling of complex discrete event dynamic systems. It illuminates the features on describing properties of causality and concurrency. Moreover, it is well-known that synchronized timed Petri net (STPN) allows us to present all of the concurrent states in complex TPN. In this paper, we propose a new methodology to design, analyze and implement an urban emergency vehicle preemption control system by using STPN. The applications of STPN to two-phase traffic lights and emergency vehicle preemption are illustrated. The advantage of the proposed approach is the clear presentation of traffic lights’ behaviors in terms of conditions and events that cause the preemption phases alternations. Finally, a two-phase traffic lights control system with emergency vehicle preemption will be realized by using STPN. To our knowledge, this is the first work that employs STPN to model a two-phase traffic lights control system with emergency vehicle preemption system.

Abstract: The study applied the gross error theory to the transformer fault diagnosis, proposing a method for transformer fault diagnosis by integrating the gross error examination and the characteristic gas ratio method. In this way it is possible to judge whether the transformer is in face of an incipient fault by examining the gross errors of the measurement series of the fault characteristic gases, at the same time the fault probability could be calculated according to the remarkable level. And then in combination with the characteristic gas ratio method, the fault category and fault cause of the transformer could be figured out. The method has been validated by an actual example of fault diagnosis.

Abstract: The wavelet analysis is a time-frequency analysis method, which plays an important role in processing non-stationary signals obtained by Particle Image Velocimetry (PIV) to measure turbulent flow fields. Current research status for wavelet analysis in the flow field structure was reviewed: eduction of coherent structures and multi-scale structures(the large-, intermediate- and relatively small-scale structures)by wavelet transform and combine with the maximum energy criterion, extraction of coherent vortical structures and analysis of multi-scale turbulent structures information from the time–frequency diagram. Application of wavelet analysis in the flow structures was also prospected.

Abstract: Because observers’ attention to the region of interest is higher than other parts (the background) of the image , This paper discribes an improved H.264 codec algorithm based on regions of interest. This method according to the degree of regional interest, adjusting the quantization step size, quantified the region of interest in detailed, and coarsely quantized other regions. ROI information was transmitted to the decoder and then carried out corresponding inverse quantization. Experimental results show that the output bit rate was decreased of 10% -20% by using this improved algorithm in H.264 reference encoder, but the subjective quality of decoded image is as good as the standard H.264 encoders.

Abstract: To generate a tiny and steady force for the calibration of the ocean current sensor, a force-reduction mechanism has been performed in this paper. The paper focuses on the whole process of this mechanism based on the flexible hinges from the working principle, parameter determination to FEM simulation and so forth. By analyzing the relationship between reduction multiple and structural parameters of the levers and hinges, material and geometric dimension are chosen reasonably. Finally, applicability of the choice of the mechanism is verified through finite element analysis. The simulation results show that using this mechanism the input force can reduce to required force of µN for the calibration.

Abstract: It is necessary for dam concrete construction to take some measures to avoid large haulage equipment collision accident. A collision avoidance system based on GPS and GIS is established in order to reduce this accident with providing accurately monitoring and controlling in real time. In this paper, the function design of collision avoidance is detailed discussed, and the integrity of the system is verified through application used in Dagan Mountain dam concreting construction.

Abstract: This paper presents a design of gas injection system for the electron beam ion trap and an approach of estimation of the injection efficiency based on geometrical optics model. The differential pumping structure is used to ensure efficient injection without destroying the vacuum. The estimation is proved reliable and reasonable by experiments results.

Abstract: The mathematical models of the double function flywheel system were built based on experimental tests and theoretical analysis in the course of energy storage and attitude control. Due to significant changes of the system model parameters in the experiment, the difference between the up and down flywheel-electrical machinery unit are compensated through the cascade compensation, and then the PID compound control algorithm with integral separation and formula partition is put forward. Experiments show that overshoot is restrained effectively and stable control is realized in high speed and wide range synchronously. The angel of the platform can be stabilized within 1°, namely the attitude affection should be controlled less than 1.2′ according to the flywheels in satellite.

Abstract: The test system we discussed is made up of a personal computer, hard wares with various functions, graphical interfaces application software Lab Windows/CVI which is used to data analysis and process communication. It mades the computer to be a numeral platform with various test functions. Making use of the software Lab Windows/CVI, various instrument panels are generated. Data could be done with, expressed, transformed, stored, and displayed on these panels.

Abstract: This paper adopts high-speed fixed-point signal processor TMS320DM64 produced by TI company, XC2S150 chip FPGA produced by Xilinx company, video front-end decoder chip SAA7111 and back-end encoding chip AL250 new launched by PHILIP company, which constituted a high-speed, intelligent live video monitoring system. The system video image transmission of strong real-time, high efficiency and good transmission quality can meet the requirements of many video image processing and transmission field application in current, and has a good application prospect. The design of system software and hardware that introduced in this paper is the key.