Advanced Materials Research Vols. 108-111

Abstract: To resolve the reliability assessment of the large-sized complex products under small samples, with the aid of the Dirichlet prior distribution and Bayesian theory, a new method is proposed in this paper. The method can fully apply Dirichlet prior information and test data to estimate the reliabilities of the products, and forecasting the success times during the products test. Compared other methods, it is simple, direct, solid, and high-effective. The investigations show that the method is quit handy and effective.

Abstract: Constant variably acceleration motion model of flying plate is proposed and the model formula about the relationship between speed of flying plate and clearance is put forward, which provides theorotical basis for choosing optimum clearance by collision speed of different metallic materials in explosive welding industry production. High pressure impulse X radial photograph experiment was carried out, the photos of the flying stances of flying plate in different clearances were obtained and the corresponding flying speeds of flying plate were calculated. Curve fitting of the experiment data through constant variably acceleration motion model was carried out. The results show that constant variably acceleration motion model accords well with the experiment data，and the maximum speed of flying plate calculated through constant acceleration model is in good agreement with the values through theoretical calculation. Therefore, it is concluded that the motion of flying plate in the main follows the constant variably acceleration motion.

Abstract: In order to improve the information management of the modern digital agriculture, combined several modern digital agriculture technologies, namely wireless sensor network (WSN), global positioning system (GPS), geographic information system (GIS) and general packet radio service (GPRS), and applied them to the information collection and intelligent control process of the modern digital agriculture. Combining the advantage of the local multi-channel information collection and the low-power wireless transmission of WSN, the stable and low cost long-distance communication and data transmission ability of GPRS, the high-precision positioning technology of the DGPS positioning and the large-scale field information layer-management technology of GIS, such a hybrid technology combination is applied to the large-scale field information and intelligent management. In this study, wireless sensor network routing nodes are disposed in the sub-area of field. These nodes have GPS receiver modules and the electric control mechanism, and are relative positioned by GPS. They can real-time monitor the field information and control the equipment for the field application. When the GPS position information and other collected field information are measured, the information can be remotely transmitted to PC by GPRS. Then PC can upload the information to the GIS management software. All the field information can be classified into different layers in GIS and shown on the GIS map based on their GPS position. Moreover, we have developed remote control software based on GIS. It can send the control commands through GPRS to the nodes which have control modules; and then we can real-time manage and control the field application. In conclusion, the unattended automatic wireless intelligent technology for the field information collection and control can effectively utilize hardware resources, improve the field information intelligent management and reduce the information and intelligent cost.

Abstract: According to the resources performance and status information provided by grid monitoring system, this paper adopts a trend-based time series prediction algorithm to predict short-term performance of the resources. Experiments show that the improved mixed trend-based prediction algorithm tracks the trend of data changes by giving more weight, simultaneously takes the different situations of data increases and decreases into account, so the improved algorithm is superior to the pre-improved and it improves the accuracy of the prediction effectively.

Abstract: The research of using wireless sensor network to settle the problem of urban traffic has become a hotspot in the fields of intelligent transportation system. In this paper, a wireless sensor network model based on mobile agents is proposed. Since mobile agents have characteristics of autonomous collaboration and asynchronous interaction, this model owns the abilities of adapting to the dynamic network changes, reducing the network load and enhancing the data fusion. In the application of the model, the travelers can be guided to choose the right road line through calculation of the predicated value of traffic congestion, so the condition of the traffic congestion can be remitted in some way.

Abstract: Network’s life cycle and the energy expending rates of mote are important performance criterions for wireless sensor networks (WSN). An improved routing protocol based on LEACH was proposed in this paper to prolong the network’s life cycle. The improved routing protocol took the circumstance into consideration, that is every mote knows the location information of its own and that of the base station. We analyzed that how to use these location information to extend the mote’s life cycle. And then the extension of the entire network life cycle was achieved. Simulation on the NS2-environment was conducted. And the experimental results show that the whole network’s life cycle was extended greatly.

Abstract: This article presents a low-energy-cost space location system based on WSN technology by applying random sampling algorithm, this system can locate a person real time who holds sensor node and adopt a representation method based on random sampling, so that the location algorithm can represent arbitrary distribution. According to the comparison of the simulation results demonstrates that the movement trajectory acquired by this system is very close to the real movement trajectory, and the number of location errors does not rely on the number of sampling numbers very obviously.

Abstract: The method of rotor position detection and its signal processing circuit for high speed permanent magnet synchronous motor (PMSM) are proposed in this paper. The optoelectronic position sensor and appropriate processing way are adopted to obtain position information accurately and rapidly. The experimental result shows that the method can accurately detect the rotor position for a PMSM with rated speed of 60000 r/min. The method is also applied on high speed PMSM direct torque control (DTC) system by simulation in this research. It is shown that the proposed method can be used for high speed PMSM which has provided theoretical basis for closed-loop control.

Abstract: In order to automatically determine the optimal threshold in image segmentation, this paper presented a new method of image segmentation based on improved genetic algorithm combined with mutual information; it used this improved genetic algorithm to globally optimize infrared image segmentation functions. This method could automatically adjust the parameters of genetic algorithm according to the fitness values of individuals and the decentralizing degree of individuals of the population, and kept the variety of population for rapidly converging to get the optimal thresholds in image segmentation, it overcame the shortcomings including worse convergent speed, easy to premature that exist in traditional genetic algorithm etc.

Abstract: The high resolution and wide measurement range are important for the displacement measurement based on the grating moiré fringe at present. 50lines/mm coarse grating scale is chosen often in order to carry out the wide range. Therefore, the realization of the high resolution is a difficult problem for coarse grating scale. The paper proposes a new nanometer subdivision method with CCD based on the disadvantages of previous moiré fringe collection method. CCD replaces the traditional photoelectric triode and converts moiré fringe to the pixels signal output, which can improve the moiré fringe quality of grating scale. The pixel is the basis unit of CCD; the pixel number decides directly the measurement resolution and precision. The paper chooses the liner array CCD TCD1501C that has 5000 pixel units and 7μm pixel unit，which ensures the nanometer resolution. The output signals of CCD are processed by amplifier, filter, 12 bit analog-digital converter and sent to the core processor of FPGA. The FPGA consisted of all digital system including CCD driver, subdivision, identification direction, displacement calculation, display and key control functions. The paper gave the principle of nanometer subdivision, block diagram of FPGA module and simulation waveforms.