Current Issue

28 December 2009, Volume 20 Issue 6
Design of radiation hard phase-locked loop at 2.5 GHz using SOS-CMOS
Partha Pratim Ghosh, Lu Mingyu & Jung Sungyong
2009, 20(6):  1159-1166. 
Abstract ( )   PDF (837KB) ( )  
Related Articles | Metrics

Abstract: A radiation hard phase-locked loop (PLL) is designed at 2.5 GHz using silicon on sapphire complementary metal-oxide-semiconductor process. Radiation hardness is achieved through improving circuit design without sacrificing real estate. Stability is guaranteed by a fully self-bias architecture. The lock time of PLL is minimized by maximizing the loop bandwidth. Frequency tuning range of voltage controlled oscillator is significantly enhanced by a novel load configuration. In addition, multiple bias stages, asynchronous frequency divider, and silicon on sapphire process jointly make the proposed PLL more radiation hard. Layout of this PLL is simulated by Cadence Spectre RF under both single event effect and total induced dose effect. Simulation results demonstrate excellent stability, lock time < 600 ns, frequency tuning range [1.57 GHz, 3.46 GHz], and jitter < 12 ps. Through comparison with PLLs in literatures, the PLL is especially superior in terms of lock time and frequency tuning range performances.

Effective method for tracking multiple objects in real-time visual surveillance systems
Wang Yaonan, Wan Qin & Yu Hongshan
2009, 20(6):  1167-1178. 
Abstract ( )   PDF (1300KB) ( )  
Related Articles | Metrics

An object model-based tracking method is useful for tracking multiple objects, but the main difficulties are modeling objects reliably and tracking objects via models in successive frames. An effective tracking method using the object models is proposed to track multiple objects in a real-time visual surveillance system. Firstly, for detecting objects, an adaptive kernel density estimation method is utilized, which uses an adaptive bandwidth and features combining colour and gradient. Secondly, some models of objects are built for describing motion, shape and colour features. Then, a matching matrix is formed to analyze tracking situations. If objects are tracked under occlusions, the optimal “visual” object is found to represent the occluded object, and the posterior probability of pixel is used to determine which pixel is utilized for updating object models. Extensive experiments show that this method improves the accuracy and validity of tracking objects even under occlusions and is used in real-time visual surveillance systems.

New chaotic system and its hyperchaos generation?
Bao Bocheng1, 2, Liu Zhong1 & Xu Jianping3
2009, 20(6):  1179-1187. 
Abstract ( )   PDF (691KB) ( )  
Related Articles | Metrics

To seek for lower-dimensional chaotic systems that have complex topological attractor structure with simple algebraic system structure, a new chaotic system of three-dimensional autonomous ordinary differential equations is presented. The new system has simple algebraic structure, and can display a 2-scroll attractor with complex topological structure, which is different from the Lorenz’s, Chen’s and L¨u’s attractors. By introducing a linear state feedback controller, the system can be controlled to generate a hyperchaotic attractor. The novel chaotic attractor, hyperchaotic attractor and dynamical behaviors of corresponding systems are further investigated by employing Lyapunov exponent spectrum, bifurcation diagram, Poincar′e mapping and phase portrait, etc., and then verified by simulating an experimental circuit.

Lattice structure adaptive IIR notch filter based on least square kurtosis
Liang Hong, Hong Kang & Yang Changsheng
2009, 20(6):  1188-1192. 
Abstract ( )   PDF (406KB) ( )  
Related Articles | Metrics

A new variable step-size algorithm for a second-order lattice form structure adaptive infinite impulse response (IIR) notch filter to detection and estimation frequency of sinusoids in Gaussian noises is proposed. Utilizing least square kurtosis of output signals as a cost function, the new gradient-based algorithm to update frequency of the adaptive IIR notch filter and the new variable step-size algorithm are given. The computer simulation results show that the proposed algorithm has better ability in suppressing colored Gaussian noises and better accuracy in estimating parameters at low SNR than previous algorithms.

Performance and EXIT analysis of parallel concatenated space time trellis codes?
Yang Haifen1, Li Guangjun1, Guo Zhiyong1 & Xiong Yong2
2009, 20(6):  1193-1197. 
Abstract ( )   PDF (226KB) ( )  
Related Articles | Metrics

Space time trellis coding (STTC) techniques have been proposed to achieve both diversity and coding gains in multiple input multiple output (MIMO) fading channels. But with more transmit antennas STTCs suffer from the design difficulty and complexity increasing. This paper proposes a scheme, named parallel concatenated space time trellis codes (PC-STTC), to achieve the tradeoff between the performances and complexity of STTCs for a large number of transmit antennas. Simulation results and complexity comparison are provided to demonstrate the performance and superiority of the proposed scheme over conventional schemes in fast fading channels in low signal-to-noise ratio (SNR) regions. And an EXIT (extrinsic information transform) chart is given to analyze the iterative convergence of the proposed scheme. It shows that PC-STTC has better iterative convergence in low SNR regions.

Target-tracked prioritization to surveille ballistic missiles?
Luo Kaiping & Li Yijun
2009, 20(6):  1198-1206. 
Abstract ( )   PDF (219KB) ( )  
Related Articles | Metrics

The missile-tracked priority assessment for the early warning system monitoring multi-missile very well, is the first task to defend them and useful to perform optimally the sensor-to-missile assignment. The problem of the missile-tracked priority assessment is of incomplete information, of multi-attribute and dynamic. To solve the difficult problem, the index system, which includes six classification indices, is established by means of reducing the target’s primary information which the early warning system focuses on. The lack of some attributes values, which is caused by the incomplete information, is handled by the approach: first classifying each attribute as unknown one or known one, and then subdividing the latter, last using the expectation and the information entropy if the attribute is known but uncertain. With a view of reality, nine qualitative evaluation criteria are given. Based on them each index is quantified by the eigenvector method. And then based on the improved technique for order preference by similarity to ideal solution (TOPSIS), the targets-tracked priorities are assessed and sorted by an evaluation function from three aspects: 1) the quantity of the available information, 2) the affirmative or accurate degree of the available information, 3) the classification or trait of the available information.

Single link tracking scheme based on UWB localization
Xiao Zhu1,2, Xiong Hailiang1, Yu Quan1,3 & Yi Kechu1
2009, 20(6):  1207-1212. 
Abstract ( )   PDF (187KB) ( )  
Related Articles | Metrics

To investigate the low-complex and high-precise tracking method, a novel single link tracking scheme based on UWB localization is proposed. Two antenna arrays are settled at the fixed station (FS) to receive the UWB signal from mobile terminal (MT), one FS is enough for the proposed scheme to track the MT. The UWB multipath detection algorithm for time difference of arrival (TDOA) estimation is presented and TDOA is thus adopted to estimate angle of arrival (AOA), avoiding the synchronization and complicated beamforming for AOA. The impacts of localization errors, concluding multipath and non-line-of-sight (NLOS) errors are simulated for the proposed track scheme. It is demonstrated that the simulation curve can match the real target moving, and the feasibility of the proposed scheme is proved.

Optimum selection of common master image for ground deformation monitoring based on PS-DInSAR technique
Zhu Zhengwei, & Zhou Jianjiang
2009, 20(6):  1213-1220. 
Abstract ( )   PDF (256KB) ( )  
Related Articles | Metrics

Considering the joint effects of various factors such as temporal baseline, spatial baseline, thermal noise, the difference of Doppler centroid frequency and the error of data processing on the interference correlation, an optimum selection method of common master images for ground deformation monitoring based on the permanent scatterer and differential SAR interferometry (PS-DInSAR) technique is proposed, in which the joint correlation coefficient is used as the evaluation function. The principle and realization method of PS-DInSAR technology is introduced, the factors affecting the DInSAR correlation are analysed, and the joint correlation function model and its solution are presented. Finally an experiment for the optimum selection of common master images is performed by using 25 SAR images over Shanghai taken by the ERS-1/2 as test data. The results indicate that the optimum selection method for PS-DInSAR common master images is effective and reliable.

Efficient parallel adaptive array beamforming algorithm
Huang Fei, Sheng Weixing & Ma Xiaofeng
2009, 20(6):  1221-1226. 
Abstract ( )   PDF (215KB) ( )  
Related Articles | Metrics

For a large-scale adaptive array, the heavy computational load and the high-rate data transmission are two challenges in the implementation of an adaptive digital beamforming system. An efficient parallel digital beamforming (DBF) algorithm based on the least mean square algorithm (PLMS) is proposed. An appropriate method is found to partition the least mean square (LMS) algorithm into a number of operational modules, which can be easily executed in a distributed-parallel-processing fashion. As a result, the proposed PLMS algorithm provides an effective solution that can alleviate the bottleneck of high-rate data transmission and reduce the computational cost. PLMS requires less computational load than that of the conventional parallel algorithms based on the recursive least square (RLS) algorithm, as well as it is easier to be implemented to do real time adaptive array processing. Moreover, low sidelobe of the beam pattern is obtained by constraining the static steering vector with Tschebyscheff coefficients. Finally, a scheme of the PLMS algorithm using distributed-parallel-processing system is also proposed. The simulation results demonstrate that the PLMS algorithm has the same interference cancellation performance as that of the conventional LMS algorithm. Moreover, the PLMS algorithm can obtain the same good beamforming performance, regardless how the algorithm is partitioned. It is expected that the proposed algorithm will be used in a large-scale adaptive array system to deal with real time adaptive digital beamforming processing.

Multiple model tracking algorithms based on neural network and multiple process noise soft switching
Nie Xiaohua
2009, 20(6):  1227-1232. 
Abstract ( )   PDF (237KB) ( )  
Related Articles | Metrics

A multiple model tracking algorithm based on neural network and multiple-process noise soft-switching for maneuvering targets is presented. In this algorithm, the “current” statistical model and neural network are running in parallel. The neural network algorithm is used to modify the adaptive noise filtering algorithm based on the mean value and variance of the “current” statistical model for maneuvering targets, and then the multiple model tracking algorithm of the multiple processing switch is used to improve the precision of tracking maneuvering targets. The modified algorithm is proved to be effective by simulation.

Dominance property based tabu search for single machine scheduling problems with family setups?
Jin Feng, Song Shiji & Wu Cheng
2009, 20(6):  1233-1238. 
Abstract ( )   PDF (165KB) ( )  
Related Articles | Metrics

The problem of minimizing the maximum lateness on a single machine with family setups is considered. To solve the problem, dominance property is studied and then introduced into the tabu search (TS) algorithm. With the dominance property, most unpromising neighbors can be excluded from the neighborhood, which makes the search process always focus on the most promising areas of the solution space. The proposed algorithms are tested both on the randomly generated problems and on the real-life problems. Computational results show that the proposed TS algorithm outperforms the best existing algorithm and can solve the real-life problems in about 1.3 on average.

Rough law generation and its separation-recognition?
Li Dongya, Ren Xuefang & Shi Kaiquan
2009, 20(6):  1239-1246. 
Abstract ( )   PDF (198KB) ( )  
Related Articles | Metrics

By using function S-rough sets (function singular rough sets), this paper gives rough law generation and the theorem of rough law generation. Based on these results above, the paper proposes rough law separation, the theorem of rough law separation, the compound generation theorem of rough law bands, and the principle of rough law bands. In the end, an application of rough law separation in recognizing the risk law of profit is presented.

Generalized ordered weighted averaging operators based methods for MADM in intuitionistic fuzzy set setting?
Wang Shuqi, Li Dengfeng & Wu Zhiqian
2009, 20(6):  1247-1254. 
Abstract ( )   PDF (187KB) ( )  
Related Articles | Metrics

Multiattribute decision making (MADM) problems, in which the weights and ratings of alternatives are expressed with intuitionistic fuzzy (IF) sets, are investigated. Firstly, the relative degrees of membership and the relative degrees of non-membership are formulated as IF sets, the weights and values of alternatives on both qualitative and quantitative attributes may be expressed as IF sets in a unified way. Then a MADM method based on generalized ordered weighted averaging operators is proposed. The proposed method is illustrated with a numerical example.

Budget constrained flow interception location model for congested systems?
Hu Dandan, Yang Chao & Yang Jun
2009, 20(6):  1255-1262. 
Abstract ( )   PDF (206KB) ( )  
Related Articles | Metrics

To study location problems with congestion demand, a bi-objective model based on flow interception problem is proposed. The model is formulated from the view of M/M/m queuing systems. Service quantity and quality are simultaneously considered as objectives, with constraint on total cost. Service quality includes deviation distance from preplanned trips and customers’ waiting time. Service quantity is the number of interception customers. A multi-objective evolutionary algorithm combined with greedy heuristic is proposed. Finally a computational experiment is given, and the algorithm is proved to be efficient.

Backstepping-based active fault-tolerant control for a class of uncertain SISO nonlinear systems?
Meng Lingya & Jiang Bin
2009, 20(6):  1263-1270. 
Abstract ( )   PDF (192KB) ( )  
Related Articles | Metrics

Active fault-tolerant control is investigated for a class of uncertain SISO nonlinear flight control systems based on the adaptive observer, feedback linearization and backstepping theory. Firstly an adaptive observer is constructed to estimate the fault in the faulty system. A new fault updating law is presented to simplify the assumption conditions of the adaptive observer. The asymptotical stability of the observer and the uniform ultimate boundedness of the fault estimation error are guaranteed by Lyapunov theorem. Then a backstepping-based active fault-tolerant controller is designed for the faulty system. The asymptotical stability of the closed-loop system and uniform ultimate boundedness of the tracking error are proved based on Lyapunov theorem. The effectiveness of the proposed scheme is demonstrated through the numerical simulation of a flight control system.

Near-optimal cumulative longitude low-thrust orbit transfer
Yue Xincheng, Yang Ying & Geng Zhiyong
2009, 20(6):  1271-1277. 
Abstract ( )   PDF (259KB) ( )  
Related Articles | Metrics

The indirect method for the continuous low-thrust near minimum cumulative longitude orbit transfer problem is addressed. The movement of the satellite is described by the Gauss equation using the modified equinoctial elements and replacing time as the system independent variable by the cumulative longitude. The maximum principle is adapted to design the optimal control in order to minimize the final cumulative longitude, and the twopoint- boundary-value problem is derived from the orbit transfer problem. The single shooting method is applied in a numerical experiment, and the simulations demonstrate that the orbit transfer mission is fulfilled and the product of the maximal thrust and the minimum cumulative longitude is near constant.

Improved block matching approach to fast disparity estimation?
Tao Tangfei, Ja Choon Koo & Hyouk Ryeol Choi
2009, 20(6):  1278-1285. 
Abstract ( )   PDF (266KB) ( )  
Related Articles | Metrics

An improved block matching approach to fast disparity estimation in machine vision applications is proposed, where the matching criterion is the sum of the absolute difference (SAD). By evaluating the lower bounds, which become increasingly tighter for the matching criteria, the method tries to successively terminate unnecessary computations of the matching criteria between the reference block in one image and the ineligible candidate blocks in another image. It also eliminates the ineligible blocks as early as possible, while ensuring the optimal disparity of each pixel. Also, the proposed method can further speed up the elimination of ineligible candidate blocks by efficiently using the continuous constraint of disparity to predict the initial disparity of each pixel. The performance of the new algorithm is evaluated by carrying out a theoretical analysis, and by comparing its performance with the disparity estimation method based on the standard block matching. Simulated results demonstrate that the proposed algorithm achieves a computational cost reduction of over 50.5% in comparision with the standard block matching method.

Robust H∞ controller design for a class of nonlinear fuzzy time-delay systems?
Wang Miaoxin, Liu Jizhen, Liu Xiangjie & Liu Juncheng
2009, 20(6):  1286-1289. 
Abstract ( )   PDF (119KB) ( )  
Related Articles | Metrics

The problem of fuzzy modeling for state and input time-delays systems with a class of nonlinear uncertainties by fuzzy T-S model is addressed. By using the linear matrix inequality (LMI) method, the problem of fuzzy robust H∞ controller design for the system is studied. Assuming that the nonlinear uncertain functions in the model considered are gain-bounded, a sufficient condition for the robustly asymptotic stability of the closed-loop system is obtained via Lyapunov stability theory. By solving the LMI, a feedback control law which guarantees the robustly asymptotic stability of the closed-loop system is constructed and the effect of the disturbance input on the controlled output is ruduced to a prescribed level.

Novel TPN control algorithm for exoatmospheric intercept
Chen Lei & Zhang Bing
2009, 20(6):  1290-1295. 
Abstract ( )   PDF (203KB) ( )  
Related Articles | Metrics

A novel control algorithm with fixed pulse thrust, based on true proportional navigation (TPN), is proposed for exoatmospheric intercept. According to the TPN guidance law and pulse thrust characteristics, the principle of control command is presented, the control stability and precision are analyzed. With the help of the TPN guidance law, the algorithm can automatically modulate the turn-on time and duration of the thrust, which could effectively limit the impact of measure noise of the line-of-sight (LOS) angle and rate on the interception miss-distance. At last, the number-theoretic method (NTM) is introduced to acquire the relation between control algorithm and miss-distance, even as it simulates the intercept process with initial state noise. And the reliability of the algorithm is demonstrated with the simulation result.

Asymptotic controllability of a class of discrete-time systems with disturbances?
Cai Xiushan, Wang Xiao & Xu Xiuling
2009, 20(6):  1296-1300. 
Abstract ( )   PDF (121KB) ( )  
Related Articles | Metrics

This article deals with the uniformly globally asymptotic controllability of discrete nonlinear systems with disturbances. It is shown that the system is uniformly globally asymptotic controllability with respect to a closed set if and only if there exists a smooth control Lyapunov function. Further, it is obtained that the control Lyapunov function may be used to construct a feedback law to stabilize the closed-loop system. In addition, it is proved that for periodic discrete systems, the resulted control Lyapunov functions are also time periodic.

Predictive control for mechanical system with backlash based on hybrid model?
Dou Lihua, Dong Lingxun, Chen Jie & Xia Yuanqing
2009, 20(6):  1301-1308. 
Abstract ( )   PDF (209KB) ( )  
Related Articles | Metrics

The mechanical system with backlash is distinguished between a “backlash mode” and a “contact mode”. The inherent switching between the two operating modes makes the system a prime example of hybrid system. For eliminating the bad effect of backlash, a piecewise affine (PWA) model of the mechanical servo system with backlash is built. The optimal control of constrained PWA system is obtained by taking advantage of model predictive control (MPC) method, and the explicit solution of MPC in a look-up table form is figured out by combining the dynamic programming and multi-parametric quadratic programming, thereby establishing an explicit hybrid model predictive controller. Furthermore, a piecewise quadratic (PWQ) function for guaranteeing the stability of closed-loop control is found by formulating the search of PWQ function as a semi-definite programming problem. In the tracking experiments, it is demonstrated that the explicit hybrid model predictive controller has a good traction control effect on the mechanical system with backlash. The error meets the demands of real system. Further, compared to the direct on-line computation, the computation burden is reduced by the explicit solution, thereby being suitable for real-time control of system with short sampling time.

Construction of compact RBF network by refining coarse clusters and widths?
Zeng Delu, Zhou Zhiheng & Xie Shengli
2009, 20(6):  1309-1315. 
Abstract ( )   PDF (472KB) ( )  
Related Articles | Metrics

It is known that centers, widths, and weights are three mainly considered factors in constructing a radial basis function (RBF) network. This paper aims at constructing a compact RBF network with two main steps. In the first step, the coarse clusters computed from triangle inequalities are refined to obtain the locations of centers by the defined maximum degree spanning tree (MDST). Meanwhile the coarse widths are obtained. In the second step, a learning algorithm referred to as anisotropic gradient descent method is presented to further refine the above coarse widths. Experiments of the proposed algorithm show its great performance in times series prediction and classification.

Margin optimization algorithm for digital subscriber lines based on particle swarm optimization*
Tang Meiqin, & Guan Xinping
2009, 20(6):  1316-1323. 
Abstract ( )   PDF (302KB) ( )  
Related Articles | Metrics

The margin maximization problem in digital subscriber line (DSL) systems is investigated. The particle swarm optimization (PSO) theory is applied to the nonconvex margin optimization problem with the target power and rate constraints. PSO is a new evolution algorithm based on the social behavior of swarms, which can solve discontinuous, nonconvex and nonlinear problems efficiently. The proposed algorithm can converge to the global optimal solution, and numerical example demonstrates that the proposed algorithm can guarantee the fast convergence within a few iterations.

3D face registration based on principal axis analysis and labeled regions orientation
Guo Zhe, Zhang Yanning, Lin Zenggang & Liu Yantong
2009, 20(6):  1324-1331. 
Abstract ( )   PDF (456KB) ( )  
Related Articles | Metrics

A novel multi-view 3D face registration method based on principal axis analysis and labeled regions orientation called local orientation registration is proposed. The pre-registration is achieved by transforming the multi-pose models to the standard frontal model’s reference frame using the principal axis analysis algorithm. Some significant feature regions, such as inner and outer canthus, nose tip vertices, are then located by using geometrical distribution characteristics. These regions are subsequently employed to compute the conversion parameters using the improved iterative closest point algorithm, and the optimal parameters are applied to complete the final registration. Experimental results implemented on the proper database demonstrate that the proposed method significantly outperforms others by achieving 1.249 and 1.910 mean root-mean-square measure with slight and large view variation models, respectively.

Proportional rate scheduling based on QoS in mobile WiMAX networks
Fang Lintang & Zhang Xiaolin
2009, 20(6):  1332-1335. 
Abstract ( )   PDF (398KB) ( )  
Related Articles | Metrics

A new scheduling scheme based on users’ quality of service (QoS) in mobile WiMAX networks is presented. The proposed scheme tracks each user’s average rate and adjusts the corresponding scheduling weight adaptively to result in: (a) each user’s average rate is proportional to the corresponding QoS level; (b) the constraints of the minimal and/or maximal rates required by QoS can be satisfied; (c) the utility function of system is maximal under the constraints (a) and (b). Theoretical analysis based on utility function and simulation results indicates the system throughput can be improved dramatically in the proposed scheme.

Computation model and improved ACO algorithm for p//T?
Yi Yang & Lai Jieling
2009, 20(6):  1336-1343. 
Abstract ( )   PDF (189KB) ( )  
Related Articles | Metrics

Scheduling jobs on parallel machines to minimize the total tardiness (p//T) is proved to be NP hard. A new ant colony algorithm to deal with p//T (p//T ACO) is addressed, and the computing model of mapping p//T to the ant colony optimization environment is designed. Besides, based on the academic researches on p//T, some new properties used in the evolutionary computation are analyzed and proved. The theoretical analysis and comparative experiments demonstrate that p//T ACO has much better performance and can be used to solve practical large scale problems efficiently.

Large scale classification with local diversity AdaBoost SVM algorithm
Chang Tiantian, Liu Hongwei & Zhou Shuisheng
2009, 20(6):  1344-1350. 
Abstract ( )   PDF (272KB) ( )  
Related Articles | Metrics

Local diversity AdaBoost support vector machine (LDAB-SVM) is proposed for large scale dataset classification problems. The training dataset is split into several blocks firstly, and some models based on these dataset blocks are built. In order to obtain a better performance, AdaBoost is used in each model building. In the boosting iteration step, the component learners which have higher diversity and accuracy are collected via the kernel parameters adjusting. Then the local models via voting method are integrated. The experimental study shows that LDAB-SVM can deal with large scale dataset efficiently without reducing the performance of the classifier.

Distributed event region fault-tolerance based on weighted distance for wireless sensor networks?
Li Ping, Li Hong & Wu Min
2009, 20(6):  1351-1360. 
Abstract ( )   PDF (1158KB) ( )  
Related Articles | Metrics

Event region detection is the important application for wireless sensor networks (WSNs), where the existing faulty sensors would lead to drastic deterioration of network quality of service. Considering single-moment nodes fault-tolerance, a novel distributed fault-tolerant detection algorithm named distributed fault-tolerance based on weighted distance (DFWD) is proposed, which exploits the spatial correlation among sensor nodes and their redundant information. In sensor networks, neighborhood sensor nodes will be endowed with different relative weights respectively according to the distances between them and the central node. Having syncretized the weighted information of dual-neighborhood nodes appropriately, it is reasonable to decide the ultimate status of the central sensor node. Simultaneously, readings of faulty sensors would be corrected during this process. Simulation results demonstrate that the DFWD has a higher fault detection accuracy compared with other algorithms, and when the sensor fault probability is 10%, the DFWD can still correct more than 91% faulty sensor nodes, which significantly improves the performance of the whole sensor network.

Cooperative game theoretic load balancing scheme with admission control in IEEE 802.11 WLANs?
L¨u Na, Zhang Yuetong & Zhang Guopeng
2009, 20(6):  1361-1365. 
Abstract ( )   PDF (197KB) ( )  
Related Articles | Metrics

A load-balancing scheme for IEEE 802.11 WLANs based on cooperative game theory is presented. A coalition among the access points (APs) with overlapping coverage is formed to share the network load through a game. Firstly, the candidate APs submit their load-competing strategies (i.e., the amount of user traffic they can admit in an AC/game period) to the control AP. Secondly, the control AP solves the game by the method of shapley value, which is the maximum traffic allocated to each AP in an AC/game period. Finally, the game is repeated periodically to distribute the traffic load among the APs. Simulation results show that the proposed game can balance the network load effectively compared with the IEEE 802.11 standard balancing solution.

Fuzzy color morphological sieves?
Yang Miao, & Wei Zhiqiang
2009, 20(6):  1366-1372. 
Abstract ( )   PDF (479KB) ( )  
Related Articles | Metrics

To solve the problems that exist in the color morphological sieves, a new fuzzy color morphological sieve is proposed. The method adopts color fuzzy model to define extrema and selects more rational regional merging way to produce better results. It can deal with the maxima or the minima areas respectively and the approach is simple and agile in design. The color fuzzy model and the steps of the algorithm are discussed. The evaluation of the performance shows the new method can produce the best synthetical performance.

Computer-aided design of classical linear compensators with application to aerospace
Amir Nassirharand
2009, 20(6):  1373-1377. 
Abstract ( )   PDF (127KB) ( )  
Related Articles | Metrics

A new Matlab function based on a versatile compensator design approach is developed. This function allows design of lead-lag, PID, proportional plus rate feedback, proportional-integral plus rate feedback, and nth order linear compensators. The primary inputs to this function are the plant transfer function and the desired closedloop behavior in terms of an nth order transfer function. The output is the particular compensator parameters. The unified design approach is primarily based on minimizing a mean-squared error type objective function. This minimization gives the compensator parameters in terms of a set of linear simultaneous algebraic equations. This solution method requires the user to input such parameters as the lower and upper limits of frequency range of interest; such parameters are automatically determined by the use of numerical optimization. The design method and the associated software are demonstrated by solving a flexible satellite problem, and the results are compared with those obtained by two other methods reported in the open literatures.

Random testing for system-level functional verification of system-on-chip?
Ma Qinsheng1, Cao Yang1,2, Yang Jun1 & Wang Min3
2009, 20(6):  1378-1383. 
Abstract ( )  
Related Articles | Metrics

In order to deal with the limitations during the register transfer level verification, a new functional verification method based on the random testing for the system-level of system-on-chip is proposed. The validity of this method is proven theoretically. Specifically, testcases are generated according to many approaches of randomization. Moreover, the testbench for the system-level verification according to the proposed method is designed by using advanced modeling language. Therefore, under the circumstances that the testbench generates testcases quickly, the hardware/software co-simulation and co-verification can be implemented and the hardware/software partitioning planning can be evaluated easily. The comparison method is put to use in the evaluation approach of the testing validity. The evaluation result indicates that the efficiency of the partition testing is better than that of the random testing only when one or more subdomains are covered over with the area of errors, although the efficiency of the random testing is generally better than that of the partition testing. The experimental result indicates that this method has a good performance in the functional coverage and the cost of testing and can discover the functional errors as soon as possible.

Damage effect analysis and experiment for electronic equipment in impact vibration environment
Shi Quan, Tian Juan & Man Qiang
2009, 20(6):  1384-1388. 
Abstract ( )   PDF (159KB) ( )  
Related Articles | Metrics

This paper analyzes the electronic equipment’s effect factors such as structure characteristics and environment. The radar equipment is taken as an experimental subject. The damage laws of electro-products in vibration environment are analyzed. The experiment shows that the damage of electro-products in vibration environment has relations with both the type and amplitude of vibration and their structure.