Volume 35,Issue 2,2012 Table of Contents

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  • 1  The effects of wall parameters on CH4 catalytic combustion in micro-channels
    RAN Jing-yu QIN Chang-lei WU Sheng
    2012, 35(2):1-9. DOI: 10.11835/j.issn.1000-582X.2012.02.001
    [Abstract](2004) [HTML](0) [PDF 10.48 M](1328)
    Abstract:
    The paper uses CFD simulation to investigate the catalytic surface reaction and heat loss characteristics of premixed CH4/air in micro-channels with Platinum catalyst. A 3D model is used with the detailed surface elementary reaction mechanism, which includes the coupled heat transfer of wall and flow domain, solid wall thermal conductivity and the convection and surface radiation between wall and the environment. The results show that the thermal conductivity has a big impact on the uniformity of wall temperature. The convective heat transfer coefficients and the surface emissivity are the key factors to determine the external heat loss of micro-combustor. An increase of wall depth can reduce the external heat loss per unit area, but it increases the total heat loss. The change of the amount of heat loss changes the reaction rate and residence time of mixed gas in the channel, which affect the methane conversion. The research indicates that the material with bigger thermal conductivity is better to fabricate micro-combustors, and the multi-methods are needed to reduce the wall heat loss.
    2  Uncertainty analysis for SOFC-PEM hybrid systems
    YANG Chen TAN Ling-jun
    2012, 35(2):10-16. DOI: 10.11835/j.issn.1000-582X.2012.02.002
    [Abstract](1883) [HTML](0) [PDF 8.45 M](1081)
    Abstract:
    This article takes SOFC-PEM hybrid systems as the research object and considers the operating parameters to be uncertainty. Uncertainty analysis method based on Latin hypercube sampling involves quantifying the uncertainty in the input parameters in the form of appropriate distribution functions, propagating the uncertainty through a deterministic model to construct the output variability distributions, and analyzing the effects of operational parameter uncertainty on system output. Furthermore, non-traditional sensitivity analysis approach is used to evaluate the relative importance of various parameters considering this distribution structure. Results show that higher operating temperature of SOFC stack, lower fuel rate and lower fuel utilization of SOFC stack can reduce the influence of uncertainty on system output at the expense of system output. Uncertainty analysis can provides more credible basis for the optimization of design parameters under uncertainty.
    3  Image segmentation by regularization on graphs
    ZENG Xiao-ping CHENG Ke-li LIU Guo-jin
    2012, 35(2):17-21. DOI: 10.11835/j.issn.1000-582X.2012.02.003
    [Abstract](2081) [HTML](0) [PDF 6.07 M](1328)
    Abstract:
    A new digital image segmentation method based on regularization on graphs is proposed, which applied a regularized diffusion framework to solve the image segmentation problem with supervised learning. The weight of the graph is generated by using Gaussian Kernel Function, combining with the geometric feature extracted from the image with contourlet transform and the color feature with HSI decomposition. The graph topology structure is an improved 8-connection topology whose step is 2k,k=0,1,2,3. Experimental results show that, compared with some graph spectral theory based image segmentation algorithms, such as Random Walker and the Lazy Snapping, the proposed method is robust for noisy pictures, which can reserve more complete boundary and have better performance on the section with inconsistent texture.
    4  Research on reliability evaluation model for frequency collapse of power grid
    LU Jing-jing SHEN Li LI Bo-qing ZHAO Yuan WU Xiao-ping
    2012, 35(2):22-27. DOI: 10.11835/j.issn.1000-582X.2012.02.004
    [Abstract](2790) [HTML](0) [PDF 5.25 M](1242)
    Abstract:
    In order to comprehensively consider the possibility and the severity of frequency instability risk, this paper proposes the risk evaluation model and algorithm for frequency collapse of power grid. The uncertainties in generating dispatch, network topology and component outage are considered. The calculation method for system frequency variation is depicted while considering the active power deficiency arising from random failure of generating units, and then various probabilistic risk indices for frequency collapse are defined. The presented method can provide important reference information for evaluating the frequency collapse risk of power grid. The non-sequential Monte Carlo simulation-based results of IEEE-RTS79 show the correctness of the method.
    5  Feature and risk identification of super karst water burst in deeply buried karst tunnel
    LIU Xin-rong ZHANG Xu-dong HUANG Ming LI Xiao-hong
    2012, 35(2):28-34. DOI: 10.11835/j.issn.1000-582X.2012.02.005
    [Abstract](2440) [HTML](0) [PDF 7.99 M](1168)
    Abstract:
    With the acceleration of tunnel construction, emerging issue of high-pressure karst water burst becomes more and more complex, and the study subject of analyzing and grasping its features and taking effective risk control measures is still a world-class long-standing puzzle. Based on the feature analysis of the karst water burst disaster during the construction of karst tunnels at home and abroad, the special water burst accompanied with high pressure water burst, earth burst and rock burst is defined as super karst water burst. With the analysis of super karst water burst which happened in Maluqing Tunnel of Yi-Wan Railway, five basic characteristics of super karst water burst are obtained, and its risk sources are also identified from the respects both of geology and human engineering activities. Based on the theoretical analysis, numerical simulation and on-site engineering experience, several threshold conditions for the occurrence of super karst water are identified. In response to implementation plan of risk identification, the method of advanced horizontal drilling with drainage test and closed water test is also proposed.
    6  Construction of 3-dimensional formation flight model and adaptive robust control
    LI Bin WANG Qiang CHAI Yi FENG Yun-hao DU liu
    2012, 35(2):35-40. DOI: 10.11835/j.issn.1000-582X.2012.02.006
    [Abstract](1975) [HTML](0) [PDF 6.01 M](1040)
    Abstract:
    The relative motion model of UAVs formation flight is constructed with tensor analysis, and the system energy function is constructed with the estimations of the external disturbances during flight. According to Lyapunov stability criterion, an adaptive robust control law is presented to keep the UAVs formation flight. The research results show that the proposed UAVs formation flight tensor model has broad applicability, and provides new ways to the further research of the UAVs formation flight as well as new ways to overcome the computing problem resulting from the singular point of the body frame, while the proposed control law is simple and effective.
    7  A design process modeling method for airplane general arrangement in the cooperative development mode
    WANG Kai LIU Yi LI Wen-zheng
    2012, 35(2):41-46. DOI: 10.11835/j.issn.1000-582X.2012.02.007
    [Abstract](2007) [HTML](0) [PDF 7.97 M](1058)
    Abstract:
    To tackle the problems not having explicit semantics and powerful analysis ability of the traditional task decomposition and process modeling methods for airplane design in the cooperative development mode, an airplane general arrangement process modeling method based on task-related WBS and Petri nets is presented. On the basis of airplane system WBS, the TR-WBS model is built by using five constraint relations including optional, mandatory, choice, precedence, and feedback. By mapping the airplane general arrangement process model into a Petri net based model, the static structure description and dynamic analysis of airplane general arrangement design tasks is obtained, and the integration of the task decomposition and the process modeling is realized. The correctness, effectiveness and applicability of the method are verified through the established airplane general arrangement and coordination system.
    8  Natural vibration characteristic of large hyperbolic cooling towers
    SHEN Guo-hui WANG Ning-bo SUN Bing-nan LOU Wen-juan
    2012, 35(2):47-54. DOI: 10.11835/j.issn.1000-582X.2012.02.008
    [Abstract](1554) [HTML](0) [PDF 9.04 M](1081)
    Abstract:
    The paper uses the finite element method to study the vibration characteristics of large hyperbolic cooling towers. Taking a typical tower for example, the distribution of the natural frequencies and mode shapes are investigated. The equations to estimate the fundamental frequency and overturning frequency are fitted based on a series of parametric studies. The results show that the fundamental frequency is directly proportional to the concrete material property〖KF(〗E/ρ〖KF)〗 and the thickness of tower wall, and inversely proportional to the height of tower. The fundamental frequency also has a quadratic relationship with the total cross-sectional area of supporting columns and the median regressive parameter. The good matches between the results from the fitting equation and the results from full-scale tests indicate that the fitting equation has a high credibility in predicting the natural frequencies of cooling towers.
    9  Optimal sensor deployment scheme for heterogeneous wireless sensor networks
    LI Ming SHI Wei-ren
    2012, 35(2):55-59. DOI: 10.11835/j.issn.1000-582X.2012.02.009
    [Abstract](2183) [HTML](0) [PDF 5.30 M](1591)
    Abstract:
    For the high density of distributed heterogeneity nodes in wireless sensor networks (WSNs), the optimal sensor deployment is studied. A cost optimal heterogeneous sensor deployment scheme based on genetic algorithm is proposed. The cost of sensor node deployment is used as objective function for optimization computation subjected to network coverage and fault tolerance to obtain the suitable types and positions of the sensors. The algorithm can be used for boolean sensing model as well as probabilistic sensing model. The simulation results demonstrate that the proposed algorithm converges fast toward the optimal solutions and reduces the cost of sensor deployment, which is feasible for heterogenous nodes deployment in WSNs.
    10  Kinetic characteristics of ignition process of diesel surrogate fuel
    WANG Feng ZHENG Zhao-lei HE Zu-wei ZHANG Qing-feng WANG Ying LI Yan
    2012, 35(2):60-64. DOI: 10.11835/j.issn.1000-582X.2012.02.010
    [Abstract](2369) [HTML](0) [PDF 6.47 M](1320)
    Abstract:
    The purpose of this paper is to identify the effects of toluene and the toluene content which is at different initial temperatures on the ignition delay time of diesel surrogate fuel under homogeneous charge compression ignition (HCCI) engine condition. The CHEMKIN4.1 module (closed homogeneous batch reactor) is used with the constructed diesel surrogate fuel chemical kinetics model to simulate the constant volume. The results show that the ignition property is mainly characterized by n-heptane. The presence of the slowly oxidizing toluene in the surrogate fuel does not affect the auto-ignition time considerably. In addition,the influence of toluene content on the ignition delay time is significant only at low initial temperature. More ignition delayed combustion processes have been found when toluene content is increasing.
    11  A malware analysis method based on symbolic execution tree
    ZHONG Jin-xin WEI Geng-yu AN Jing YANG Yi-xian
    2012, 35(2):65-70. DOI: 10.11835/j.issn.1000-582X.2012.02.011
    [Abstract](2210) [HTML](0) [PDF 6.20 M](2000)
    Abstract:
    In the malware analysis, it is a common method to monitor malware dynamically in a virtual environment. However, with so many branches of executable pathes, path explosion problem will probably occur, leaving some executable pathes uncovered, and hence harming the comprehensiveness of analysis. To solve this problem, we propose a malware analysis method based on symbolic execution tree. This method introduces sinknode and solves the execution of malicious code path by constructing the symbolic execution tree, so improves the analysis of comprehensive. Experiments to analyze the samples of malware show that the method can enhance the efficiency of the analysis with lower time complexity.
    12  An effective automatic detection system for multi-protocol attack
    YANG Yuan-yuan MA Wen-ping LIU Wei-bo ZHANG Xiao-xiao
    2012, 35(2):71-77. DOI: 10.11835/j.issn.1000-582X.2012.02.012
    [Abstract](1855) [HTML](0) [PDF 5.88 M](1205)
    Abstract:
    Since there exists multi-protocol attack when several security protocols are co-executed in a computer network, an automatic detection system for multi-protocol attack (ADMA) is proposed. The system is composed of two parts named protocol search subsystem and attack verification subsystem. According to the consistency condition of the type of encrypted messages between the target protocol and the secondary protocol, the protocol search subsystem can automatically search for the candidate secondary protocols, which may be used to attack the target protocol. By improving the SAT-based model checking, attack verification subsystem can automatically verify whether multi-protocol attack exists between the target protocol and the candidate secondary protocols or not. The experiment results show that ADMA system can implement automatic detection for multi-protocol attack, and some new multi-protocol attacks are found in the detection.
    13  Simulation analysis on stimulation patterns of three-dimension electrical impedance tomography
    LI Bing HE Wei HE Chuan-hong XU Zheng ZHANG Zhan-long
    2012, 35(2):78-86. DOI: 10.11835/j.issn.1000-582X.2012.02.013
    [Abstract](2164) [HTML](0) [PDF 12.00 M](2013)
    Abstract:
    To solve the lack of information and the error in forward and inverse problem caused by the approximation of actual three-dimensional field from two-dimensional field in electrical impedance tomography (EIT), this article presents a new EIT system. This system improves one-dimensional electrode array to two-dimensional array, and extends the solution domain to the entire three-dimensional field in order to increase the information quantity and eliminate the model error. Based on several current stimulation patterns in EIT which might yield the best sensitiveness for 3-D field, we calculate the forward problem by finite element method and the distinguishability and surface projection image method. The results show that the back electrode pattern has obvious advantages in detecting depth and precision, and has convenience in clinical application. The conclusion of this article can provide reference for the study of 3-D EIT.
    14  Nonlinear dynamics bond graph model for a spur gear pair system
    TANG Jin-yuan CHEN Hai-feng
    2012, 35(2):87-91. DOI: 10.11835/j.issn.1000-582X.2012.02.014
    [Abstract](2431) [HTML](0) [PDF 4.82 M](1640)
    Abstract:
    A nonlinear dynamics bond graph model of gear pair system is established including the time-varying gear mesh stiffness, transmission error and tooth surface conditions. A capacitive component c is introduced to represent the loads and tooth elastic deformation, while the capacity parameter Kj is expressed by time-varying mesh stiffness, and flow Sf represents the influences of the gear transmission error on the system dynamic equations. Then the tooth surface friction bond graph model involving the relationship between the relative velocity and the direction of friction are presented. According to the causal relations and the power flow, the state-space equations of the gear bond graph model are obtained. Research results show that bond graph modeling method can solve the modeling problem of the gear nonlinear dynamics, and this paper is a kind of basis work of the complex mechanical system modeling and the development of bond graph modeling theory.
    15  Prediction of calibration interval for a measuring instrument using rolling grey bootstrap fusion model
    SUN Qun ZHAO Ying PAN Quan-ke
    2012, 35(2):92-97. DOI: 10.11835/j.issn.1000-582X.2012.02.015
    [Abstract](1667) [HTML](0) [PDF 5.48 M](1310)
    Abstract:
    A rolling grey bootstrap fusion model (RGBFM(1,1)) is proposed to predict calibration interval of a measuring instrument under small sample. The model combines GM(1,1) model with bootstrap method. Bootstrap re-sampling is used in the process of modeling the grey differential coefficient function to mine more information about systems. Both the instantaneous value and interval assessment values can be predicted using RGBFM(1,1), which can reduce prediction risk of calibration interval. In contrast, other prediction models only predict the instantaneous value. Experiments show that the RGBFM(1,1) can exactly describe the random wave of original sample data in prediction of instantaneous value, interval upper limit and lower limit, and has higher prediction reliability. Therefore, the RGBFM(1,1) is suitable for the prediction of calibration interval for a measuring instrument.
    16  A frequency-domain image registration algorithm using the improved polar transform
    Guo Yong-cai He Wei-hua Gao Chao
    2012, 35(2):98-104. DOI: 10.11835/j.issn.1000-582X.2012.02.016
    [Abstract](2126) [HTML](0) [PDF 7.94 M](2181)
    Abstract:
    The traditional polar transform usually suffers from the non-uniform sampling problem, which means that the low-frequency components are often over-sampled, while the high-frequency components are relatively under-sampled. Consequently, the inappropriate sampling rates will affect the registration accuracy, or else increase the computation cost vainly. To conquer the drawbacks mentioned above, we develops a novel frequency-domain registration algorithm using the improved polar transform. The reference image and the image to be registered are both carried out Fourier transform individually, and the corresponding spectrum images are sequentially mapped into the improved polar coordinate. Then projection operations are done along the angular and radius direction, respectively. As a result, the rotation and scale parameters between the two spatial images can be easily induced from the corresponding projection curves. Eventually, the shift parameters are retrieved with the weighted phase difference, after the inverse rotation and scale operations are implemented for the image to be registered. The experimental results show that the registration precision of our algorithm is much higher than the algorithm using the traditional polar transform or the pseudo-polar transform, while the required computation costs are almost equivalent.
    17  Average surface roller pressure calculation method of roller mill
    DU Bo CHEN Shi-jiao QIN Da-tong WU Yi-xiao LIN Yu-pei
    2012, 35(2):105-111. DOI: 10.11835/j.issn.1000-582X.2012.02.017
    [Abstract](1754) [HTML](0) [PDF 8.37 M](1204)
    Abstract:
    Hydraulic system pressure, contact surface between grinding roller and materials and grinding roller force of roller mill are analyzed. A new roller pressure calculation method named average surface roller pressure calculation method is proposed,and the corresponding theoretical formula is derived from three different perspectives, including roller pressure numerical calculation, stress and strain of main components and mill power through the calculation of real samples. The average surface roller and traditional average material roller pressure are compared to verify the correctness and accuracy of the proposed method. Design parameters such as the grinding roller structure, material maximum size, layer height and working pressure of the hydraulic system on the influence of roller are analyzed according to the formula of roller pressure. The research results provide theoretical basis for the selection of design parameters and the design calculation of structural strength for roller mill.
    18  Design and development of propulsion system for CNG-electric hybrid city-bus
    SHU Hong-yu WANG Kun CHEN Qi-ping TIAN Ye DAI You-wen
    2012, 35(2):112-117. DOI: 10.11835/j.issn.1000-582X.2012.02.018
    [Abstract](1815) [HTML](0) [PDF 5.56 M](1358)
    Abstract:
    The design of propulsion system for CNG-electric hybrid city-bus is introduced based on the selection of driving cycle and the establishment of control strategy. Making program of powertrain’s configuration is included as well as parameters’ selection and matching of components such as engine, motor, battery and transmission. The simulation results show that the design meets the requirements. The components of the propulsion system are integrated together, and then they are installed into the sample city-bus. The roadway test has been done under the target driving cycle. Compared with the peer CNG city-bus, there are 28% increasing in the largest climb degree and the acceleration time of 0~50 km is reduced more than 1.8 s, and the fuel saving rate achieves to 22% under the typical city-bus driving cycle of China.
    19  Modeling and dynamic simulation of pole trailer’s track on crooked road
    CHENG Bo YANG Yu LUO Xiong LI Fei
    2012, 35(2):118-122. DOI: 10.11835/j.issn.1000-582X.2012.02.019
    [Abstract](1644) [HTML](0) [PDF 5.79 M](1390)
    Abstract:
    To ensure the transportation safety of oversize/overweight(OS/OW) products, the problem of the poor passing capability of pole trailer in turning should be solved. After analysis of the pole trailer’s static structure and dynamic turning characteristics, we deduce the iterative formula of the model’s key points coordinates. The dynamic computer simulation system of the pole trailer’s turning process is developed, which can provide guidance for the pole trailer to pass the crooked road smoothly during transport process.
    20  Composite gaussian process regression model and its application to prediction of silicon content in hot metal
    REN Jiang-hong CHEN Tao CAO Chang-xiu
    2012, 35(2):123-127. DOI: 10.11835/j.issn.1000-582X.2012.02.020
    [Abstract](2633) [HTML](0) [PDF 4.91 M](1653)
    Abstract:
    In order to increase the predictive precision of gaussian process regression based soft sensor, a composite gaussian process regression model is proposed. This model combines the outputs of several gaussian process models as the output according to the variances and the distribution of the outputs, which results in higher prediction accuracy and higher robustness than the single gaussian process model. The proposed composite gaussian process regression model is successfully applied to the prediction of silicon content in hot metal.
    21  Stability assessment method for small and medium potential landslides and results analysis
    WU Yue LU Xin LIU Dong-Sheng ZHU Jiang-kai
    2012, 35(2):128-134. DOI: 10.11835/j.issn.1000-582X.2012.02.021
    [Abstract](1500) [HTML](0) [PDF 8.35 M](1128)
    Abstract:
    Small and medium landslides are widely distributed, the prediction mainly relies on the monitoring and controlling systems executed by the masses. The advantages and disadvantages of various stability assessment methods are compared. The engineering analogy method accords with the requirements for small and medium landslide assessment. A method is illustrated based on Fisher discrimiant function to cope with the small and medium potential landslide stability assessment. The impact factors of landslides is explored with the historical data. The stability is taken as a multi-dimensional statistical variable and project into one-dimensional straight line. Distance discriminant method is used to construct a classification criterion. The applicability of this method is explored, and assessed the landslides in Chongqing Wulong by this method. The results show that accuracy of this method is about eighty percent. This method is suitable for the city of Chongqing or other areas with the similar geological environment.
    22  Improved algorithm of contact element model for earthquake-induced pounding between structures
    LIU Peng ZHENG Kai-feng HE Wei LIU Hui
    2012, 35(2):135-142. DOI: 10.11835/j.issn.1000-582X.2012.02.022
    [Abstract](1685) [HTML](0) [PDF 7.37 M](1459)
    Abstract:
    To better study the issue, we presented an improved algorithm. In this algorithm, the impact issue is equivalent to a spring〖XC半字线.tif,JZ〗oscillator model which contains an oscillator, a spring and a damper. The oscillator movement represents the compression phase and restitution phase of impact. By solving the motion equation, we got the penetration displacement,penetration velocity, impact force, impact time and their mutual relationship. The solution process did not carriy out the hypothesis that the energy dissipation or absolute speed during the restitution phase is the same as that during the compression phase, which was adopted by common solution methods. Therefore we can get the exact results or approximate results that are infinitely close to the exact results. In the case of small energy dissipation during the collision, Hertzdamp model results obtaind by common solution methods are close to the exact results. When the energy dissipation during the collision is large, the difference between them becomes obvious. Regardless of small or large energy dissipation during the collision, the improved algorithm can obtain the results which are infinitely close to the exact results. 〖BP(〗Therefore, the improved algorithm has more advantages than common solution methods, especially for solving the earthquake-induced pounding problems with a large number of energy dissipation during the collision.〖BP)〗
    23  Watermarking algorithm based on Her transform
    WANG Li-peng
    2012, 35(2):143-148. DOI: 10.11835/j.issn.1000-582X.2012.02.023
    [Abstract](1617) [HTML](0) [PDF 5.92 M](1040)
    Abstract:
    Most transformations used for digital watermarking in transformation domain are orthogonal transformations, such as DCT and DWT. Three types of orthogonal transformation with excellent performance are found by studying three systems of orthogonal functions: Haar function system, Haar type function system and Walsh function system. Her transformation is one of the three transformations. Her function system can not be used directly in digital watermarking as DCT matrix being used, since Her matrix of Her function system is not normalized orthogonal matrix. The corresponding discrete matrix is obtained by sampling Her continuous functions, and successfully used in digital watermarking with a series of experiments and theoretical analysis. A digital watermarking algorithm based on Her transformation is proposed. Experimental results show that the algorithm is simple and good at perceptual transparency as well as robustness of watermarking extraction. In addition, the experimental results of comparing with the traditional DCT watermarking show that this algorithm is of good robustness against noise and filtering.
    24  Image segmentation based on differential mutation bare bones particle swarm optimization and fuzzy entropy
    ZHANG Wei
    2012, 35(2):149-154. DOI: 10.11835/j.issn.1000-582X.2012.02.024
    [Abstract](1733) [HTML](0) [PDF 6.39 M](992)
    Abstract:
    Basic bare bones particle swarm optimization (BBPSO) is easy to get stuck into local optima. Based on basic BBPSO, using the idea of mutation in differential evolution, a new algorithm named differential mutation bare bones particle swarm optimization (DMBBPSO) is proposed and combined with image fuzzy entropy to obtain a new segmentation algorithm based on DMBBPSO and fuzzy entropy for image segmentation. The proposed algorithm uses DMEBBPSO to explore fuzzy parameters of maximum fuzzy entropy and gets the image segmentation threshold. According to the experiment results, compared with other two algorithms, the proposed algorithm shows better segmentation performance and very low time cost. It can be used to real time and precision measure coal dust image.

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