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Table of Content

    25 March 2012, Volume 40 Issue 3
    Chemistry & Chemical Engineering
    2012, 40(3):  1-9. 
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    There is a wide-spread interest in examining the alternative liquid fuels that are more sustainable and environmentally friendly than gasoline. In this paper,first,several alternative liquid fuels,such as biomethanol,bioethanol and biobutanol,are introduced,bioethanol being a leading one due to its potential. Then,the materials for bioethanol production are summarized,finding that lignocelluloses are paid more attentions to because the starch- or sugar-based productions are restricted by current policies. Moreover,the pretreatment methods for different kinds of lignocelluloses are analyzed,and the dilute acid pretreatment alone or that combined with steam explosion is found to be more efficient and economic than many other pretreatment
    options. However,as dilute acid has a tendency to generate compounds inhibiting fermentation,such as furfural,hydroxymethyl furfural and small-molecular lignin,some countermeasures should be taken during the analysis and process design to limit the production and impact of these compounds.

    Yang Wei Chen Sheng-zhou Dong Xin-fa Lin Wei-ming
    2012, 40(3):  10-14. 
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    Co-N-C oxygen reduction electro-catalysts for the cathode of the direct methanol fuel cell ( DMFC) were first prepared via the pyrolysis in Ar atmosphere,with melamine formaldehyde resin and cobalt nitrate as the precursors. Then,the preparation and structure of the electro-catalysts were investigated by means of TG-FTIR,XRD and element analysis,and the electro-catalytic activity for oxygen reduction reaction as well as the methanol tolerance of the electro-catalysts was detected by using a rotating disk electrode. Finally,a DMFC single-cell test was carried out by using the prepared electro-catalysts as the cathode catalysts. The results indicate that Co-N-C electro-catalysts are of high electro-catalytic activity and strong methanol tolerance,and that the onset potential of the electro-catalysts for oxygen reduction is about 0.5V ( vs.SCE) . Moreover,it is found that the catalyst prepared at 700℃ possesses the highest electro-catalytic activity for oxygen reduction reaction.

    Huang Wei-qing Li Xiu-xi Wang Jin-jin Qian Yu
    2012, 40(3):  15-21. 
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    As the flexibility analysis of many dynamic process systems ignores the effect of time delay,the operation safety cannot be guaranteed by the intrinsic flexible region in some circumstances. In order to solve this problem,a concept of sensitivity of the process system to the time delay is proposed,and the effects of time delay on the flexibility of the system are analyzed in two cases. Then,the sensitivities of different process systems to the time delay are compared,and the controller optimization and simulation as well as the controllability analysis are performed for the dynamic process system. Finally,a case study on a typical chemical reactor is carried out for the integrated analysis of the dynamic flexibility and the process controllability. The results show that the introduction of sensitivity provides a more accurate flexibility analysis for dynamic process systems and guarantees the operation safety and stability of practical process systems.

    Zhang Bin Wu Shu-bin
    2012, 40(3):  22-29,36. 
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    In this paper,the primary physical properties of the hydrolysis residues of two kinds of lignocelluloses,namely the acid hydrolysis residue of wood powder ( WAHR) and the xylose residue ( XR) ,were analyzed,and the pyrolysis characteristics of the residues and their parent materials were investigated by using a thermogravimetric analyzer and a self-developed tube furnace reactor. The results show that the residues both possess higher carbon content than their parent materials,that WAHR possesses higher carbon content than XR,that there exist great differences in the composition and pyrolysis properties of the two residues,that the yields of gaseous and liquid products of XR are higher than those of WAHR in the whole investigated temperature range,that the yields of H2 ,CO,CO2 ,CH4 ,C2H4 and C2H6 vary with the temperature in different rules,that the liquid products of the two residues are similar in species but different in content,that the CO2 gasification reactivity of chars derived from both WAHR and XR decreases with the increase in pyrolysis temperature,and that higher content of lignin in parent materials may leads to lower reactivity of chars.

    Wei Dan Xia Zheng-bin Xing Jun-heng Wang Ying-ying Zhong Li
    2012, 40(3):  30-36. 
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    The anodization of high-purity titanium was carried out via a potentiostatic approach in 0. 1 mol /L H2SO4 solution,with a traditional three-electrode cell,a high-purity titanium plate,a platinum electrode and a saturated Ag /AgCl electrode respectively as the template,the working electrode,the counter electrode and the reference electrode. Then,the effects of anodization potential and oxidation time on the formation and crystallization characteristics of the anodic titanium oxide films were analyzed,and the films were characterized by means of SEM-EDS,Raman spectroscopy and XPS. The results show that there exist anatase-phase TiO2 nano-crystals in the films prepared via an anodic oxidation at 6V,60min or at 30V,10min,and that high anodization potential and long oxidation time both promote the transformation of intermediate titanium oxides to stable titanium dioxide and accelerate the formation and growth of the anatase-phase nano-crystals,thus resulting in a structural evolution of the anodic titanium oxide films from a short-range ordered structure with few TiO2 nano-crystals to a long-range one mainly composed of anatase-phase TiO2 .

    Electronics, Communication & Automation Technology
    Ke Feng Geng Heng-xin Feng Sui-li Jiang Ming
    2012, 40(3):  37-42. 
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    Proposed in this paper is an opportunistic relaying strategy for decoding-and-forwarding wireless cooperative relay networks based on power weighting. In this strategy,the power weight is determined according to the residual energy of each node in the network,and the optimal cooperative relay of each source node is selected according to the minimum weighted-energy criterion. Moreover,the optimal power allocation between the source node and the relay node is obtained via the simplex method. Thus,the energy utilization is improved and the energy consumption of each node in the network is balanced. Simulated results show that the proposed strategy is superior to other strategies in terms of prolonging the lifetime of cooperative relay networks.

    Li Ju-hu Chen Peng He Zhi-qiang Wu Wei-ling
    2012, 40(3):  43-48,63. 
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    In MIMO-OFDM systems,channel estimation error and carrier frequency offset are two objective existing factors. In order to investigate the effect of carrier frequency offset on the performance of MIMO-OFDM systems in the presence of channel estimation error,zero-forcing detectors and an approximation to the Wishart distribution are used to theoretically deduce the signal-to-interference-plus-noise ratio and its probability distribution for the system in the presence of estimation errors of Rayleigh and Rician fading channels,and the average error probability as well as the outage probability of the system is further obtained. Simulated results indicate that,in the presence of channel estimation error,even a small carrier frequency offset may greatly impact the performance of MIMO-OFDM systems.

    Yang Hai-yan You Zheng Wang Lin
    2012, 40(3):  49-56. 
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    In the accurate tracking of multiple targets in clutter by using a collaborative network system with hierarchical and distributed information processing structure,both the measurement uncertainty and the sensor assignment to the target as well as the local fusion centers must be taken into consideration. In order to solve these problems,a dynamic sensor management method for distributed tracking is proposed. In this method,first,the criteria to evaluate the tracking performance are determined based on the solution to the modified Riccati difference equation,with which the objective function of the dynamic sensor management is constructed. Then,according to a hierarchical optimization strategy and by using the improved ant colony algorithm,an approximate optimal solution is obtained in real time. Finally,the optimal multi-target tracking trajectories are obtained by using a distributed fusion algorithm. Simulated results indicate that,as compared with the two dynamic sensor management methods,namely NN-Clustering and MV-Clustering,the proposed method is of higher multi-target tracking accuracy and higher utilization rate of network resource.

    Zhang Wen-zhu Zhao Bei
    2012, 40(3):  57-63. 
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    Efficient routing algorithm is the key to guaranteeing the performance of delay-tolerant network ( DTN) . In order to improve the efficiency of DTN routing algorithms,a routing algorithm based on gradient and fuzzy neural network decision is proposed. This algorithm improves the vector for network description by adopting the own information of a node and the link state information between two nodes,which enables a comprehensive description of the network. Moreover,it provides accurate measurement for routing decisions by combining the dynamic average of limited historical information with an accurate prediction and by adaptively maintaining the components of the vector. In addition,fuzzy RBF ( Radical Basis function) neural network is employed in the algorithm for routing decision so as to result in an intelligent routing decision-making process,and,the successful multi-hop packet transmission probability is used to guide the forwarding along the gradient,thus improving the packet forwarding efficiency. Simulated results indicate that the proposed algorithm achieves better performance than epidemic and context-aware routing algorithms under the same network conditions.

    Yan Bing-hui Li Bin Yao Ruo-he Wu Wei-jing
    2012, 40(3):  64-68,125. 
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    The drain current model of the polysilicon thin film transistor ( poly-Si TFT) based on surface potential can not accurately describe the discrete grain boundary distribution,while the threshold-voltage-based model is not capable of continuously representing the drain currents in different operation regions. In order to solve these problems,a direct drain current model of the poly-Si TFT considering the discrete distribution of grain boundary potential in drains is established based on the surface potential. The proposed model describes the drain currents of the poly-Si TFT in different operating regions via an analytic equation.  Simulated results indicate that,when the poly-Si TFT works in the linear region at a certain gate bias,its effective mobility decreases with the increase in drain voltage,and that,with the increase in gate bias or with the decrease in channel length,the effect of drain voltage on the effective mobility weakens.

    Wei Rong-shan Chen Shou-chang Chen Jin-feng He Ming-hua
    2012, 40(3):  69-73. 
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    A novel hybrid SET /CMOS inverter is proposed in this paper based on the negative differential resistance ( NDR) characteristics that are realized by connecting one single electron transistor ( SET) and one PMOS transistor in series. In this inverter,two monostable points for realizing the inverting function are constructed by utilizing the NDR characteristics and NMOS transistor’s current-voltage characteristics. By using a compact subcircuit model of the SET and a 22 nm predictive technology model ( PTM) of the CMOS transistor,the operation of the hybrid SET /CMOS inverter is then simulated with an HSPICE simulator. The results show that the inverter works well,with its power consumption lower than that of the traditional CMOS inverter,and that the proposed inverter is superior to other SET inverters because it achieves a full-swing output voltage and a smaller transmission delay at room temperature.

    Luo Jia-xiang Luo Shu-hao Wu Xin-sheng
    2012, 40(3):  74-80. 
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    The optimization of component picking and mounting sequences is a major way of improving the efficiency of surface mounting machine in electronic assembly line. Seeking good component picking and mounting sequences with a given feeder allocation is helpful in minimizing the mounting distance and in improving the mounting efficiency. In this paper,a mathematical programming model is established and an improved tabu search algorithm based on the referenced local search ( RLS) is proposed. In the algorithm,double tabu lists are designed to avoid circuitous search,and a RLS strategy based on the inserting of mounting cycles is implemented to improve the algorithm’s ability of escaping local optima. Experiments are also carried out on the mounting data for 20 printed circuit boards. The results show that the proposed algorithm outperforms the existing one since it achieves better solutions.

    Zhang Qian Pei Hai-long Shi Bu-hai Zhao Yun-ji
    2012, 40(3):  81-87. 
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    In order to meet the requirements of high reliability,easy use,low cost,high accuracy and speed for the machine vision system to detect surface stains of non-woven fabric products,an embedded machine vision system,which integrates a human-computer interface to avoid the inconvenience induced by PC dependence,is designed. Then,the hardware structure of the system is introduced,and a dynamic threshold-based method is proposed to detect the stains in real time with high precision,low misjudgment rate and strong reliability. Practical application results indicate that the proposed system is of high performance,concretely,in a non-woven fabric production line with a linear velocity of 300 m/min,it can successfully detect the stain with 1 mm2 in square.

    Zhao Yun-ji Pei Hai-long
    2012, 40(3):  88-93. 
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    In order to realize stable articulated object tracking,an algorithm based on incremental learning is proposed. In this algorithm,the graph-cut algorithm is used to obtain a foreground image by segmenting the rectangular object region,and a fast Fourier transform is conducted for the foreground image to obtain the Fourier coefficient matrix and to further acquire the amplitude image as the description of the tracking object. Then,the low-dimension subspace representation of the tracking object is obtained by the singular value decomposition and the principle component analysis of the amplitude image. Thus,the tracking algorithm is realized in the framework of particle filtering. Experimental results indicate that the proposed algorithm helps to achieve stable articulated object tracking.

    Guo Ling Li Zhen-zhen Du Ming-hui
    2012, 40(3):  94-99. 
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    For the location detection of a moving target in surveillance videos,the existing locating and tracking systems mainly based on binocular or structured-light stereo vision techniques are of high system design complexity and low speed. In order to remedy these drawbacks,a new method of moving target tracking based on monocular sequence images is proposed by introducing a ground constraint. In this method,the formulas to estimate the position of moving target in asymmetric nonlinear imaging are derived according to camera´s installation information and geometrical imaging principle together with nonlinear compensation. By setting up an indoor monitoring and test platform,an experiment looking for a walker’s foot position in an image sequence is carried out,and the results verifies the effectiveness of the proposed method.

    Yan Yi-ming Zhang Ye Gao Feng-jiao
    2012, 40(3):  100-105. 
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    In order to optimize the target information acquisition technology by prudently selecting observing angles and to collect maximum information with the fewest observing points,a multi-side decomposition-based information content description model is proposed,which is used to measure the target information collected by optical image sensors at different observing angles. The main idea of this model is that,to estimate the information collected at different observing angles,the target is decomposed into multiple sides,and its information is described by the combined vector of the information collected from all sides. Moreover,the modified bee colony algorithm is utilized to search the optimal observing angle and to further obtain the maximum information content. The proposed method is then applied to the planning simulation of observing angles in the target information acquisition of an unmanned aerial vehicle with multi-temporal and relative observation. Experimental results show that the proposed optimization method improves the average information acquisition by 58.5%,and that it helps to perform efficient planning with maximum information acquisition when observing angles are limited.

    He Jun Li Yan-xiong He Qian-hua Li Wei
    2012, 40(3):  106-111. 
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    As the commonly-used weighting algorithm is inefficient in tracking the abnormal feature of abnormal speech,a speaker recognition algorithm for abnormal speech is proposed based on the abnormal feature weighting. In this algorithm,first,a feature template of normal speech is established by computing the probability distribution of MFCC features of each order in a large number of normal speech samples. Then,the K-L distance and the Euclidean distance are used to measure the differences between a given test speech and the normal speech templates and to further determine the K-L and the Euclidean weighting factors. Finally,the two weighting factors are used to weight the MFCC features of the test speech,and the weighted MFCC features are input in the Gaussian mixture model for the speaker recognition with abnormal speech. Experimental results show that the global recognition rates of the speaker recognition algorithms based on the K-L weighting and the Euclidean weighting are respectively 46.61% and 42.25%,while those of the algorithms with and without the weighting of speaker recognition contribution of each order feature are respectively only 39.68% and 36.36%.

    Ma Xiao-lu Qiu Jin-hao Ji Hong-li Li Sheng-quan Zhu Kong-jun
    2012, 40(3):  112-118. 
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    Both the passive and the active piezoelectric vibration methods are of poor performance because the former is of some branch circuit parameters sensitive to environmental changes and a complex branch circuit and the latter requires higher input power. In order to solve these problems,an active-passive hybrid control method is proposed based on the piezoelectric branch circuit with negative capacitance and the adaptive algorithm with wavelet transform. The authors describe the principle of the hybrid control method and analyze the influences of negative capacitance value on the passive control effect and the active control voltage. Simulated and experimental results show that the hybrid control method effectively suppresses the structural vibration and is more effective than the individual active or passive control method.

    Wang Rui-ping Shi Bu-hai Pi You-guo
    2012, 40(3):  119-125. 
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    In order to implement the high-efficiency velocity control of AC permanent magnet synchronous motors,a fractional-order PI controller satisfying the system stability and robustness is proposed. Then,for the purpose of evaluating the performance of the controller,a comparison between the designed controller and the conventional optimal integer-order PI controller is made via simulations and prototype experiments. The results show that the designed fractional-order PI controller outperforms the optimal integer-order one in terms of the load disturbance resistance and the robustness to open-loop gain variation.

    Zhang Bi-tao Pi You-guo
    2012, 40(3):  126-130. 
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    In order to overcome the chattering existing in the conventional first-order sliding mode controller and the static error resulting from the fuzzy control system,a fuzzy fractional-order sliding mode controller,which integrates the advantages of sliding mode control and fuzzy control and makes use of fractional-order differential and integral calculus,is proposed for the velocity control of permanent magnet synchronous motor. Then,the design method of the controller is presented and the performance of the controller is analyzed. Simulated and experimental results indicate that the proposed controller possesses high control performance and strong robustness to external load disturbance.

    Ye Tao Li Yan Zhu Xue-feng Wu Zhi-min
    2012, 40(3):  131-136. 
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    Proposed in this paper is a therapy instrument of bladder tumor by circularly perfusing therapeutic agents under temperature control. In the investigation,first,the principle and the research status of the bladder tumor hyperthermia are introduced. Next,a simulation system of the instrument is constructed by simulating the human bladder with a glass cup. Then,the control system hardware of the instrument is designed based on an embedded microcontroller,and the control system software,which includes an μCOS-II-based architecture,a temperature measurement and control module and an μuCGUI-based graphical user interface,is developed. Finally,the corresponding hardware testing and software debugging procedures and methods are explicated,and some notable details are pointed out for the future research.

    Mechanical Engineering
    Deng Yao-hua Liu Gui-xiong
    2012, 40(3):  137-142. 
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    In order to meet the real-time requirements of the prediction model for deformation compensation of flexible workpiece path ( FWP) with complex factors,a ATS-FNN ( Adaptive TS Fuzzy Neural Network) -based modeling method for the compensation prediction of FWP machining deformation is proposed. In this method,the adaptive fuzzy clustering method is employed to obtain the antecedent fuzzy membership functions and fuzzy rule fitness of TS-FNN from historical machining data,and the steepest descent method is used as the learning algorithm of the consequent network to quickly calculate the parameters of connection weights. Simulated results indicate that,as compared with the standard TS-FNN,the ATS-FNN reduces a modeling time of 52.34% and a mean square error of the predicted compensation respectively by 36.50% or 33.34% in x or y direction.

    Yu Jun Lou Pei-huang Qian Xiao-ming Wu Xing
    2012, 40(3):  143-149. 
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    In order to improve the measurement accuracy of a monocular vision-based bidirectional automatic guided vehicle,a motion-based self-calibration method is used to reduce the system error,and a color image processing is performed to extract the centerline of the guided path. Then,a classification method of path models based on curvature estimation is proposed to meet the requirements of target accuracy. The path models are classified into three types,namely the straight line,the arc turning and the non-circular turning. Finally,the minimum mean-variance method is used for the parameter regression of the first two models,and the curvature estimation-based adaptive weighted fitting method is used for the parameter regression of the third model. Experimental results show that the proposed method is of high measurement accuracy and meets the requirement of vision navigation well.

    Li Gang Zong Chang-fu Chen Guo-ying Hong Wei
    2012, 40(3):  150-155. 
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    This paper deals with the integrated control of the active front steering ( AFS) and the direct yam moment control ( DYC) for steering-by-wire 4WID electric vehicles and proposes a hierarchical algorithm based on the model predictive control. Moreover,the corresponding model predictive controller is designed and a driving force allocation method based on the quadric programming is investigated. Finally,a simulation is carried out to verify the proposed algorithm. The results show that the proposed algorithm enables the vehicle to track the expected trajectory and improves the vehicle stability and active safety.

    Li Yong Chen Chun-yan Jie Zhi-wei Zeng Zhi-xin
    2012, 40(3):  156-161. 
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    In order to optimize the structure of sintered powder wick and improve the thermal conductivity and effi-ciency of heat pipes,the heat transfer characteristics of the sintered heat pipes with the outer diameters of 5,6 and8 mm and with a wick thickness ranging from 0.5 to 0.6 mm are discusse. The resuhs show that,when the copper particle size distribution is concentrated,both the porosity of the wick and the maximum heat transfer power (MHTP)of the heat pipe increase with the average particle size,while the temperature difference at the condensa-tion end and the total thermal resistance both slightly decreases,and that,when the particles in different sizes are mixed,the variation rules of the temperature difference at the condensation end and the total thermal resistance are different for heat pipes with different outer diameters. Moreover,it is found that the MHTP of the heat pipe decrea-ses with the copper particle size and reaches the minimum when the pipe is sintered with 70% of small-size parti-cles,that the MHTP of the heat pipe sintered with 70% of large-size particles is only second to that of the pipe sintered entirely with large-size particles,that a more concentrated particle size favors the perform ance of the heat pipe,and that copper powders with an average particle size of(165±15)Ixm is appropriate to the manufacturing of heat pipes.

    Wang Zhi-shen Li Gang-yan Zhang Hu-ping
    2012, 40(3):  162-166. 
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    Based on the analyses of the dynamic characteristics and the pneumatic circuit of dual-chamber cylinders,a model describing the dynamic characteristics,which takes into consideration the pipeline between the solenoid valve and the cylinder,is established. Then,a simulation is carried out with Matlab based on the proposed model,and an experimental system for the dynamic characteristic test of the cylinder is designed. Simulated and experimental results indicate that the proposed model theoretically describes the dynamic characteristics of dualchamber cylinders with high accuracy.

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