28 February 2012, Volume 30 Issue 6

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  • LU Chongying;XU Lixin;WANG Ting
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    A CMOS-compatible MEMS integrated on-chip inductor is designed. The square planar spiral coil program is utilized. The coils are made of copper with a higher conductivity than aluminum. In order to improve the quality factor (Q) of the inductor, thick metal coils and cavities etched in the CMOS-grade silicon substrate are designed by the MEMS technology, which can reduce the serial resistance of metal square planar spiral coils and the losses in the low resistance silicon substrate, respectively. A fully CMOS-compatible low temperature MEMS process is presented and a 1nH inductor model with thick metal coils and low-loss MEMS substrate is simulated by using HFSS software. Simulation results show that the inductor obtained by this CMOS-compatible low temperature MEMS process enjoys a high peak quality factor of 22.37 and 20.74 at 6.6GHz and 10GHz with a self-resonant frequency over 20GHz, respectively. The influences of metal coils' thickness on the quality factor and the inductance are also analyzed. When the thickness of the inductor is increased, the quality factor is increased while the inductance is decreased. The fluctuation of the inductance is less than 5.5% in the simulation frequency range.
  • LI Xiaolei;LI Jinshan;ZHONG Hong;KOU Hongchao;ZHANG Tiebang;CHANG Hui
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    A Ti-46Al-2Cr-2Nb alloy ingot was prepared by the process of double vacuum arc melting. The composition distribution and microsegregation in Ti-46Al-2Cr-2Nb alloy were studied. The microstructure and phase composition of the alloy were investigated by means of back scattered electron imaging, X-ray diffraction, energy dispersive spectrometry, and chemical composition analysis. The main results in detail are as follows:In the transverse sections, the content of Al is at the highest level in the place of R/2, however, the content of Al is low on the edge and radial zone of the ingot. The content of Cr is increased and the content of Nb is gradually decreased from the fringe to the center of the ingot, respectively. Along the longitudinal sections, the content of Al is gradually decreased from the bottom to the top of the ingot, the distribution of Cr is following the law of positive segregation elements, and the segregation law of Nb is similar to that of the Al element. The microstructure of the ingot mainly consists of α2 and γ phases. Most areas of the ingot are composed of α2+γ lamellar groups and a small amount of equiaxed γ phases at the colony boundaries, what is called nearly fully lamellar. The areas in the centre of the upper part ingot have a full lamellar structure composed of α2+γ phase. The microsegregation of the ingot exists around colony boundaries, where the microsegregation of Cr element is quite serious.
  • ZHAO Xuan;XIAO Guangpeng;MA Jian;WANG Guiping
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    The driving controller is the core component of electric vehicle, the performance of which has a direct effect on the performance and transmission efficiency of the electric vehicle. So in this paper a driving controller of electric vehicle based on Freescale S12 MCU is developed for large and medium-sized electric vehicles. An overall design program of driving controller is given according to the special requirements and operating environment of electric vehicle, among them the hardware circuit including the power supply module, the minimum system circuit of controller, the signal conditioning module circuit, the PWM output circuit, data communication module circuit and IGBT driving module circuit and so on; the fuzzy self-tuning PID control strategy is used. And a road test for the electric vehicle installed the driving controller is conducted, which indicates that the driving controller can meet the complex driving conditions, electric vehicle has better acceleration and good speed tracing and meets the relevant national regulations, therefore, the controller is applied to all types of large and medium-sized electric vehicles.
  • LIU Xingrong;ZHANG Lianke;WANG Dekai;YANG Jun;DONG Yaogang;MA Yiming
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    Zhaohegou is one of well known debris flow disastrous gullies in Chengxian County. There are 390.78×104m3 loosed solid materials in the gully with very favorable formation conditions for debris flows. In order to protect the farmland, the villages, the roads and Huangzhu city in the upper reach of Dong River, based on the formation mechanism, the developmental mechanism and the features of debris flows in Zhaohegou, this paper analyzes the seriousness of the debris flow disaster and the necessity of its prevention. A comprehensive controlling program is put forward, taking the blocking as the dominant measure,and combining the comprehensive treatments of the debris flow silting ground, the draining channel and the barrage. After the project is completed, the comprehensive benefits will be produced every year. Now the debris flow has been changed into a usual flood flow. Its threat to Dangchang town has been eliminated. The operation of the project is analyzed to reveal its engineering deficiencies. Considering the characteristics of the debris flow; the project is evaluated, focusing on the design of the control projects, the advantages of these projects and the optimizing methods. This analysis provides some guidelines for the prevention and control against debris flow.
  • ZHAO Xiutai;BAI Yingrui;WANG Zengbao;GAO Yuan;SHANG Xiaosen
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    The recovery efficiency of oil could be enhanced by using compound cross-linking polyacrylamide system of deep profile control and flooding. The formula contained main agents of a cross-linking polyacrylamide system which consisted of 0.30% HPAM, 0.08% organic chromium, and 0.10% hexamethylenetetramine is optimized by orthogonal test under the 70℃ condition. In order to prolong the gel time of system, the effects of delayed cross-linker SO on gel time and gel strength are researched. Gel time of system is 48h and gel strength is 0.057MPa when the concentration of SO is 0.04%. The performance of system could be affected by salinity, temperature, pH value, and other factors. When the concentration of Na+ is under 36,000 mg/L, the concentration of Ca2+ is below 1,000mg/L, the gel strength of system could be higher than 0.040MPa. When pH is between five and seven, the gel strength of system could be above 0.065MPa; however, the gel time is shorter. When temperature is between 60℃ and 90℃, the gel strength of system is about 0.056MPa and changes slightly, however when temperature is between 50℃ and 60℃, the gel strength of system changes greatly. The deep profile control and flooding performance of system is researched by using single tube core displacement experiment. The results show that the oil recovery could be enhanced about 20% after water flooding and the plugging rate is higher than 90% by using that system. Because the gel time of system is above 48h, therefore the performances of that cross-linking polyacrylamide system could satisfy the requirements for deep profile control and flooding in oil layers.
  • ZHANG Qiang;;FU Yunfei;YUAN Zhi;SONG Zhenduo
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    In order to break through the bottleneck in the development for the oil-coal-water slurry to serve as the alternative fuels, this paper studies the problem of substituting the oil-coal-water slurry for the diesel fuel to be used on diesel engines where solid coal particles would exacerbate the piston pump wear, and carries out a multi-phase numerical simulation to identify the media-induced piston wear mechanism. Based on the VOF multi-medium model, the Reynolds stress model and the discrete phase model for the continuous phase and the dispersed phase, the multi-medium erosion, the motion trajectory of the solid particle and the impact process between the solid particle and the machine surface are simulated. The volume content of the solid phase in the multi-medium flow is lower than 10% in this simulation model. The simulation result shows that, the related parameters of the solid particles, such as the density and the diameter, the mix proportion and the plunger speed of the impeller, would greatly influence the motion trajectory and the impaction of the solid particles with the machine surface. The solid particles with a large mass are apt to move toward the working surface and impact the inside of the piston shell. On the other hand, the small particles are liable to impact the plunger barrel assembly. The higher the plunger speed, the more plunger barrel assembly erosion will be resulted; the plunger barrel assembly wears more severely with the increase of the solid mix proportion. Simulation results agree with experimental results.
  • ZU Bo;HUANG Huancun;LONG Mingmei;GUO Yu;GAO Guijun
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    The highway is the product of social and economic development, to shorten the temporal and spatial distance between people, by providing great convenience for quick travel and communication, while also promoting the economic development and the progress of society. With the rapid economic development, the highway construction has entered an unprecedented fast lane., The number of accidents occurred on the highway is gradually increasing. The fog weather is an important influencing factor on the accidents. Therefore, it is very important to study the driving safety under foggy conditions .In this paper, experimental points are set on different function areas in Sanxikou overpass segment of Chongqing, to evaluate the driver 's and passenger 's true feelings while driving down the road in the foggy condition. From the experiment, it is found that the ecological restoration & ingenious landscape structure along both sides of the mountainous areas, which matches well with the linear pattern has certain guiding effect on the traffic safety in foggy days, to reduce the accident incidence under a heavy fog condition and to ensure driving safety. The guiding function of the ecological restoration & ingenious landscape structure along highways should be considered in the design and the construction of mountainous area highways in fog-prone areas.
  • LIU Shucong;SONG Yanxing;LIU Chang
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    In order to increase the Signal to Noise Ratio (SNR) and resolution of seismic data for the vibrator seismic exploration, according to the principle of phased-controlled sources, by means of delay and superposition on single source seismic signals, directed seismic signal is able to be equivalently synthesized for saving the cost of exploration. For horizontal single-layer and multi-layers model, the SNR of seismic waves is presented when the single source and single source directed synthesis techniques are used, and the simulation results show that the single-source directed synthetic seismic waves could effectively improve the SNR of seismic waves. Through the analysis on the SNR improvement due to the directional lighting synthesis of field data, the SNR of directional synthetic records based on single-source is improved by the average of 6.4041 dB comparing with the SNR of single source. The effects of seismic exploration are effectively improved.
  • XU Bin;WU Junjun;LIU Shuli;SUN Wenhuai
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    The RIC construction technology is a kind of new methods of foundation treatment. This paper presents a numerical analysis of the RIC method. The soil deformation is basically large in the process of using the RIC method, therefore, this paper uses the finite element method based on the large deformation theory. The influence depth, the effective reinforcement depth, and the optimal compacting count of RIC method are determined. The numerical analysis is validated by some measurements of an engineering example.
  • CHEN Jun;GUO Yubing;CAO Huifang;WANG Yong
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    The identification methods based on dynamic performance testing are discussed focusing on the features of control systems. In order to realize the online identification for the control system in a computer virtual instrument, a dynamic testing and identification system is designed, using Delphi language for several identification modules. The hardware platform of dynamic testing and system identification with the virtual instrument being used as its core component is built. In the nonlinear aspect, this paper studies the identification algorithm based on Back Propagation (BP) Neural Network algorithm, and proposes an identification algorithm named MBP Neural Network and a Wavelet Neural Network algorithm to reduce the sensitivity of the network. Finally, the real- time wavelet algorithm is simulated to verify the above conclusion. The MBP Neural Network algorithm and the Wavelet Neural Network algorithm are simulated on the three-axis platform of the partial simulating system for an anti-aircraft weapon.
  • HAMIT Murat;ZHOU Jingjing;YAN Chuanbo;LI Li;CHEN Jianjun;HU Yanting;KONG Dewei
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    The feature extraction of images is a foundational work for image recognition, image data mining, and content-based image retrieval, and it is also the key issues of pattern recognition and classification. Feature extraction based on gray-scale histograms is a typical algorithm for the medical image feature extraction. For features of liver hydatid CT images that is extracted by using different gray-scale histograms are normalizing scale by uniform quantization, the noise is removed by using a median filter, the contrast is enhanced by limited adaptive histogram equalization; and then the gray-scale histograms is used to get the features of the image. The main features of the image classification are obtained by using statistical and maximum classification distance analysis on the histogram features, and then the classification ability of features is evaluated by discriminant analysis. The result shows that there is a certain discrepancy of statistical analysis for the features extracted by gray-scale histograms; features selected by maximum classification distance enhance the accuracy of image classification. This study would lay a solid foundation for the content-based medical image retrieval and the computer-aided diagnosis system to a certain extent.
  • Reviews
  • DING Shenghu;LI Xing
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    Functionally Graded Materials (FGMs) are new composites which are able to satisfy the harsh requirements for the materials used in the high-technology fields, such as astronautics, aeronautics, national defense, etc. Since FGMs are multiple phase materials with the properties of spatial and continuous variance, they could maintain the structural rigidity, reduce the thermal stress, and resist the severe thermal loading from the high temperature environment. The extensive usage of the FGM promotes the development of fracture mechanics. A description of studies related to fracture mechanics problems of FGMs is presented, and in where four principal topics are covered, that is, static and dynamic fracture mechanics problems, thermal elastic fracture mechanics problems, and the experimental works for investigating the fracture of FGMs. Finally, recommendations are made with regard to the areas in which additional work should be done. The research on the FGMs is of great significance for optimizing the design of FGMs.
  • LI Tieqiao;LIU Chuansheng;XI Xiaohuan;WANG Xinyuan
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    The study of the cultural heritage, related with the human history in general, is a long-term and multi-disciplinary complex task with important significance. New methods and techniques such as the spatial information technology will remarkably help clarify the time and spatial characteristics of the cultural heritage. As is known, the spatial information technology has been widely used in many aspects of cultural heritage researches due to its powerful capabilities to acquire, store, represent and analyze the spatial data. This paper discuses the current status and the latest progress of the spatial information technology application in the cultural heritage from several key aspects, i.e., various detection techniques, data integration, representative visualization, spatial information intelligent analysis of heritage sites and the comprehensive application of the multiple spatial information technology. The results show that the research in this field is more and more concerned with network, integration and intelligent level.