Table of Content

28 May 2009, Volume 27 Issue 3

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Communication Engineering

Call Admission Control in TDD-CDMA-HCS System

MA Shou-gui, XIE Bo, WANG Jun-bo, CHEN Ming

2009, 27(3):  221-225. 

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Call admission control based on SINR is proposed to solve the admission problem of TDD-CDMA-HCS (time division duplexing-code division multiple access-hierarchical cell structure) system. Based on the definition of a system utility function, decision of admission is made according to the usage of resources. Both inter-layer call overflow and system-load based layer selection are implemented. Simulation results show that the call block ratio and the system drop-out ratio decrease significantly, resulting in considerable improvement of the system performance.

Adaptive Fuzzy Classification of Modulation Using Cyclic Correlation Feature

CHEN Xiao-qian, WANG Hong-yuan, KE Zhi-wu

2009, 27(3):  226-230. 

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       For non-stationary digitally modulated signals, a high definition feature, high order cyclic cross cumulant(HOCCC) for is proposed to suppress interference and noise. A novel modulation classifier based on nonlinear dynamic fuzzy neural networks (FNN) is presented.  According to the general distribution of the feature samples, we establish a fuzzy inference system with initial experiences, embed the structure and self-adaptive training of the neural network to adjust and optimize the fuzzy system parameter, and complete approximation of the fuzzy neural network modeling. For MASK, MPSK, MFSK and MQAM, simulation results show better adaptability and fault-tolerance of the system at a variety of environment parameters such as SNR. The system with initial experiences possesses a short modeling phase, and can improve average probability of correct classification and efficiency compared to neural network classifiers.

Pursuit-Evasion Policies in Wireless Sensor Networks

GUO Li-xin1, ZHAO Lei-ping2

2009, 27(3):  231-237. 

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     In view of efficiency of capture and evasion in pursuit-evasion games in wireless sensor networks, several new pursuit-evasion policies are proposed. The proposed vector-ward evasion policy can bring the evader breaking away from puzzledom between two pursuers and decrease fluctuation of evasion track. The boundary evasion policy makes the evader find a better escaping direction. The intelligent collaboration pursuit policy effectively takes advantages of collaboration efficiency of multiple pursuers and reduces capture time. The results show that the vector-ward evasion policy and intelligent collaboration pursuit policy are effective. The pursuit-evasion strategies are still valid when taking into consideration localization errors of the mobile carriers.

Linear Congruential Interleavers in IDMA

TASSING Remi1, ZHU Guang-xi1;2, LIN Pei1, CHEN Yong-hui1

2009, 27(3):  238-0243. 

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      A method based on linear congruential generator (LCG) is used to construct random interleavers for interleave-division multiple-access (IDMA). One interleaver, called the mother interleaver, is first generated and then cyclically shifted to obtain the other interleavers, each belonging to one user. We propose to choose the LCG parameters such that its maximum period is reached and, for convenience, the LCG modulus is a power of 2. With these settings, the modulus should be strictly greater than the interleaver size. A mathematical proof is provided for this matter. Out-of-bound random numbers are simply discarded. Finally, peak basis correlation and bit-error rate analysis are used to show correctness of the theoretical expectations. 

Performance of Turbo-BLAST System with Imperfect Channel State Information

CHEN Xiao-min, XU Da-zhuan, YU Xiang-bin

2009, 27(3):  244-246. 

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       For the case of imperfect channel estimation, variance of equivalent noise is found with the imperfect channel state information. A modified iterative scheme of parallel interference cancellation is then proposed using the Turbo-BLAST scheme. The scheme is suited to the Turbo-BLAST system with perfect or imperfect channel state information. Simulation results show that the proposed scheme is effective in improving BER performance.

Signal and Information Processing

Self-Organizing Map of Local Parameters for Visual Mechanism Simulation

MA Yu, GU Xiao-dong, WANG Yuan-yuan

2009, 27(3):  247-252. 

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       A self-organizing map of local parameters is proposed to simulate the initial visual processing mechanism for color scenes. The method employs local color mean values, local color contrasts, and positions as features, and uses a self-organizing map for classification to deal with multiple tasks such as image segmentation, edge detection, and contour separation. Experimental results for both synthetic and natural color images show that the method can perform these tasks simultaneously. It maps image parts with different features to different positions of the output space, conforming to the feature mapping and simultaneously processing characteristics of the visual system. This method can be used to investigate and simulate visual mechanisms, and handle multiple image processing tasks.

Novel Java Web-Based Image Mosaic System: WebPano

YAN Zhuang-zhi, SHAO Shi-jie, ZHANG Jing, PAN Rui-qi, YANG Jing-qiong

2009, 27(3):  253-0259. 

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       This paper presents the design and implementation of a web-based   image mosaic system (WebPano) based on model-view-controller frame, aiming at solving the bottleneck of application system such as user experience and service efficiency in the process of transplanting the system from desktop to web. JSP/Servlet and Java are used to implement the network platform and the image mosaic algorithm, respectively. The service of quality of the WebPano system is tested under the condition of uploading multiple high-resolution images. Furthermore, the multi-user load performance of the system is simulated and discussed with Load Runner. The test results show that the system achieves the same performance and user experience of the desktop system.

Two-Stage Texture Image Segmentation

MA Xiu-li1, JIAO Li-cheng2, WAN Wang-gen1

2009, 27(3):  260-265. 

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        Spectral clustering is a new clustering algorithm based on graph and similarity. For a very large image, it takes a long time to compute the affinity matrix, eigenvalues and eigenvectors. To apply the spectral clustering algorithm to large-scale clustering problems, a two-stage texture segmentation algorithm is proposed. An  improved watershed algorithm is used to perform pre-segmentation, followed by multiway spectral clustering with eigenvaluescaled eigenvectors to complete the segmentation. To verify the proposed algorithm, we apply it to texture image segmentation with satisfactory results.

Application of Improved τ-leap Algorithm in Stochastic Simulation of Biochemical Reaction Systems

LIU Huan1, PENG Xin-jun2;3, ZHOU Wen4, WANG Yi-fei1

2009, 27(3):  266-0271. 

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    A τ-selected strategy that ascertain the τ-value is proposed in this paper. It is developed as an improved τ-leap algorithm. The τ-selected strategy can effectively reflect change numbers of the species in biochemical systems, while the improved τ-leaping algorithm is more effective and practical to stochastic simulation of biochemical reaction systems than other algorithms. We take two models of biochemical reaction systems as examples, and carry out simulation using accurate SSA algorithm, improved τ--leaping algorithm, and the present modified τ-leap respectively. Numerical results demonstrate that, compared with modified τ-leap algorithm, the improvedτ-leap algorithm can significantly increase simulation precision with the same computation complexity under the same condition.

Electronic Engineering

Predictive Dynamic Power Management Based on Energy Expectation

HUANG Shao-min1;2, QI Long-ning1, YANG Jun1, HU Chen1

2009, 27(3):  272-276. 

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      Existing predictive dynamic power management(DPM) policies based on correlations of consecutive idle times are ineffective under stochastic service requests. In view of statistics, this paper proposes an energy expectation based (EEB) predictive policy. EEB makes components into a mode of lowest energy expectation of idle times. It is shown that the method optimizes energy saving. Simulation results show that, under exponential distribution and Pareto distribution, EEB acquires lower power of component compared with traditional predictive policies.

Computer Science and Applications

Software Reliability Evaluation Based on Software Architecture

LIANG Jun-tao1, JIANG Xiao-yuan2, ZHANG Hai3

2009, 27(3):  277-281. 

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   Current software reliability evaluation methods do not take into account the execution probability of each function and the degree of failure severity. We propose a new method for evaluating software reliability based on the software architecture. The UML-described software architecture is analyzed. Execution probability of the functions is derived, and reliability of components and connectors defined. The degree of failure severity of components and connectors are obtained according to expert experiences. A Markov model is constructed from various scenarios, and reliability of individual components and the overall system estimated using the model.  Validity of the method is shown with an ATM example.

Intelligentized Biclustering Based on Tabu Search and Genetic Algorithm

Lü Yu-long1, SHEN Qing-song1, SHI Tie-liu2, WANG Yi-fei1

2009, 27(3):  282-287. 

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     The degree of difficulty in finding significant biclusters in gene expression data grows with the increase of the size of the dataset. This paper presents an intelligent biclustering method which makes full use of the climbing ability of tabu search and genetic algorithm, balances relation between regional search and global search, and makes the results independent of a pre-defined threshold. Experiments show that the method has a better convergence property and can discover better biclusters than traditional methods.

Application of Neural Networks to Determine Limited Water Level of Reservoir Flood Routing

WU Cheng-guo1, JIN Ju-liang1, ZHOU Yu-liang2, CHENG Liang1

2009, 27(3):  288-293. 

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      The dynamic control of reservoir limited water level is the key point to resolve conflict between flood control and benefits promotion, and realize safe utilization of flood resources. At present, the limited water level is determined by using flood routing to design flood of different frequencies. Different periods in a flood season have different designed flood. Based on safety of the dam and in view of practical operations and flood control standards,BP neural networks are used in the reservoir flood routing process to fully realize the benefits promotion and raise the limited water level as far as possible in a flood season. A neural network method for determining various limited water levels of reservoir flood routing is proposed. Applications show that the method is easy for visualization and simple for implementation. The precision satisfies practical needs, and it can be used in the computation of limited water level.

Graphics Switching for Attitude Indicator in Aircraft Cockpit

JIA Yin-liang1, ZHANG Huan-chun1, JING Ya-zhi1, LIU Jing2

2009, 27(3):  294-0298. 

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      A new algorithm is presented for attitude indicator used in an aircraft cockpit to reduce the consumed time for graphics switching. The algorithm gets the coordinates of pixels in a horizontal scanning line and fills the graph with horizontal or vertical lines. This way, the horizontal buffer is not needed. Graphics in the attitude indicator are switched using less memory and less calculation time than the original algorithm.

 

Control and System

Terminal Sliding Mode Control of Singular Systems

LIANG Jia-rong1, XIAO Jian2, FAN Zhong-guang2

2009, 27(3):  299-304. 

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     The problem of terminal sliding mode control of singular systems is studied in this paper. Singular systems are transformed into equivalent forms with a nonsingular linear transformation. An exponential terminal sliding hypersurface and the corresponding controller are presented. The results show that, with this design, asymptotic stability of closed-loop systems is guaranteed while the system state variable can arrive at an equilibrium point in a finite time period. Numerical examples show that the designing method is reasonable and effective.

Adaptive Robust PID Controllers

WANG Ya-gang, XU Xiao-ming

2009, 27(3):  305-310. 

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          This paper presents a new adaptive PID controller with sensitivity specification. On the basis of process input and output data of normal operation in the control loop, important frequency responses of the process are estimated with signal decomposition and Laplace transform. A second-order and dead-time transform function is identified. PID control parameters are calculated to satisfy the sensitivity specification. The adaptive procedure of PID controller does not need any prior knowledge of the process and the previous controller to maintain normal operation of the loop. Simulation results are given to show effectiveness and feasibility of the propose adaptive PID controller.

SINS Initial Alignment Based Spherical Simplex Transformation SRUKF Algorithm

LU Hai-yong, ZHAO Wei, XIONG Jian, LAI Ji-zhou, LIU Jian-ye

2009, 27(3):  311-0315. 

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      To reduce the amount of calculation and solve the instability problem in the strapdown inertial navigation system(SINS) initial alignment of large azimuth misalignment, this paper proposes a modified square root unscented Kalman filter (SRUKF). The filter uses the spherical simplex unscented transformation to reduce the number of sigma points to speed calculation without sacrificing the filter precision. To reduce rounding errors and improve stability, the covariance matrix is replaced with a new matrix whose entries are square roots of the covariance matrix. Simulation results show that the spherical simplex SRUKF algorithm can significantly reduce the computation load and provide better filtering performance with accurate alignment.

Net Transmission Period of Multi-loop Distributed Control System

WANG Yue-fei1;2;3, HAN Jiang-hong1;2, HU Qing-xin1;2, ZHANG Ben-hong1;2

2009, 27(3):  316-320. 

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          Net transmission period (NTP) is an important parameter of safety critical distributed control system(SCDCS). To obtain NTP, a co-design method between desired control performance and network real-time scheduling is presented with a formalization description based on model-building of multi-loop SCDCS. Meanwhile, a performance function for control loop is built, and a method for getting the maximum allowable transmission interval (MATI) under prescribed stability constraint is introduced by using relative error of state and the Lyapunov theory. Simulation validates the NTP design method. The results show that the method guarantees control network schedulability, and makes control loop have desired dynamic performance.

Modeling of New Quantum Whistling Superfluid Cryogenic Gyroscope

SONG Bao-zhang, ZHAO Wei, XIE Zheng, LIU Jian-ye

2009, 27(3):  321-325. 

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     The principle and typical project of the superfluid cryogenic gyroscope using ac-Josephson effects is studied to develop a high precision gyroscope based on superfluid. Mathematical model of the gyroscope including ac-Josephson effects, relations between rotation and ac-Josephson frequency, and signal detection method is obtained. The process of gyroscope sensing constant angular velocity (earth rotation) is simulated. Scouting angular velocity changes with time and the effects on precision due to structural parameters such as sense area and diaphragm area are studied. Simulation results show that it is feasible to develop a new high precision gyroscope based on ac-Josephson effects.


Inverse Model Compensation Control of Turntable Based on Brain Emotional Learning

ZHEN Zi-yang, WANG Dao-bo, WANG Zhi-sheng, HUANG Guo-yong

2009, 27(3):  326-330. 

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      In view of the difficulty in dealing with nonlinear disturbance moments such as friction in the flight simulator’s servo system, a compound control method using a brain emotional learning (BEL) model is proposed. Based on the traditional PI feedback controller, a BEL model-based identifier and a forward compensation controller of the same structure are designed. The node weights of the BEL model are obtained through inverse model identification of the system. Simulation results of an ideal simulator model and experimental results of a real simulator servo system show that the BEL model has good learning ability and meets the real-time control requirement. Moreover, the compound control strategy based on the BEL model can effectively reduce the influence of friction moment and improve tracking performance of the simulator.