2005 Vol. 3, No. 4

Computer and Communication Technologies
mm-Wave Communication Systems at W-Band
FAN Yong, WU Zheng-de, TANG Xiao-hong
2005, 3(4): 289-292.
Two communication systems at W-band are introduced, including the system design, the modulation scheme, etc. TV delivery system delivers picture of quality meeting grade 4.5 over 8 km (no rain). Digital communication system is capable of operating at data rates up to 8.448 Mb/s beyond 10 km under a BER of 10-6 (clear).
A MEO Tracking and Data Relay Satellite System Constellation Scheme for China
WU Ting-yong, WU Shi-qi, LING Xiang
2005, 3(4): 293-297.
A medium earth orbit (MEO) tracking and data relay satellite system (TDRSS) constellation scheme for China is proposed. This system consists of MEO satellite constellation, inter-satellite links (ISLs) and terrestrial gateway station, which can provide continuous bidirectional data transmission links between low altitude spacecrafts and the terrestrial gateway station in China. Theoretical analysis and simulation results indicate that the proposed constellation can cover the global low altitude space sphere and earth surface of China continuously, and has a preferable practical perspective.
Performance Analysis of an Enhanced PRMA-HS Protocol for LEO Satellite Communication
ZHUO Yong-ning, YAN Shao-hu, WU Shi-qi
2005, 3(4): 298-303.
The packet reservation multiple access with hindering state (PRMA-HS) is a protocol suitable for LEO satellite mobile communication. Although working well with light system payload (amount of user terminals),the protocol imposes high channel congestion on system with heavy payload, thus degrades the system's quality of service. To controlling the channel congestion, a scheme of enhanced PRMA-HS protocol is proposed,which aims to reduce the collision of voice packets by adopting a mechanism of access control. Through theoretic analysis,the system's mathematic model is presented and the packet drop probability of the scheme is deduced. To testify the performance of the scheme,a simulation is performed and the results support our analysis.
Integrating Mobile Ad Hoc Network to the Internet
WANG Mao-ning
2005, 3(4): 304-309.
A novel scheme is presented to integrate mobile ad hoc networks (MANETs) with the Internet and support mobility across wireless local area networks (WLANs) and MANETs. The mobile nodes, connected as a MANET, employ the optimize d link state routing (OLSR) protocol for routing within the MANET. Mobility management across WLANs and MANETs is achieved through the hierarchical mobile IPv6 (HMIPv6) protocol. The performance is evaluated on a HMIPv6 based test-bed composed of WLANs and MANETs. The efficiency gain obtained from using HMIPv6 in such a hybrid network is investigated. The investigation result shows that the use of HMIPv6 can achieve up to 27% gain on reducing the handoff latency when a mobile roams within a domain. Concerning the reduction of the signaling load on the Internet, the use of HMIPv6 can achieve at least a 54% gain and converges to 69%.
Information and Image Processing
Particle Size Estimation Based on Edge Density
WANG Wei-xing
2005, 3(4): 310-313.
Given image sequences of closely packed particles, the underlying aim is to estimate diameters without explicit segmentation. In a way, this is similar to the task of counting objects without directly counting them. Such calculations may, for example, be useful fast estimation of particle size in different application areas. The topic is that of estimating average size (=average diameter) of packed particles, from formulas involving edge density, and the edges from moment-based thresholding are used. An average shape factor is involved in the calculations, obtained for some frames from crude partial segmentation. Measurement results from about 80 frames have been analyzed.
Prioritized MPEG-4 Audio-Visual Objects Streaming over the DiffServ
HUANG Tian-yun, ZHENG Chan
2005, 3(4): 314-320.
The object-based scalable coding in MPEG-4 is investigated,and a prioritized transmission scheme of MPEG-4 audio-visual objects (AVOs) over the DiffServ network with the QoS guarantee is proposed. MPEG-4 AVOs are extracted and classified into different groups according to their priority values and scalable layers (visual importance). These priority values are mapped to the IP DiffServ per hop behaviors (PHB). This scheme can selectively discard packets with low importance, in order to avoid the network congestion. Simulation results show that the quality of received video can gracefully adapt to network state, as compared with the best-effort manner. Also, by allowing the content provider to define prioritization of each audio-visual object,the adaptive transmission of object-based scalable video can be customized based on the content.
Circuits, Systems and Signal Processing
A Method of Time-Varying Rayleigh Channel Tracking in MIMO Radio System
GONG Yan-fei, HE Zi-shu, HAN Chun-lin
2005, 3(4): 321-324.
A method of MIMO channel tracking based on Kalman filter and MMSE-DFE is proposed. The Kalman filter tracks the time-varying channel by using the MMSE-DFE decision and the MMSE-DFE conducts the next decision by using the channel estimates produced by the Kalman filter. Polynomial fitting is used to bridge the gap between the channel estimates produced by the Kalman filter and those needed for the DFE decision. Computer simulation demonstrates that this method can track the MIMO time-varying channel effectively.
An MMSE Decoding Algorithm without Matrix Inversion in QSTBC
LIU Yu, HE Zi-shu
2005, 3(4): 325-327.
The matrix inversion operation is needed in the MMSE decoding algorithm of orthogonal space-time block coding (OSTBC) proposed by Papadias and Foschini. In this paper, an minimum mean square error (MMSE) decoding algorithm without matrix inversion is proposed, by which the computational complexity can be reduced directly but the decoding performance is not affected.
Antennas and Propagation
Progress of Expert Systems in Electromagnetic Engineering
LAI Sheng-jian, WANG Bing-zhong
2005, 3(4): 328-333.
It is urgent to solve various problems in electromagnetic (EM) engineering under the increasingly complicated environment. Some expert systems (ES) come into being just to keep up with the demand for solving these problems. Combined with the analysis of development of ES technology and the development trend of EM engineering software in recent years, the application of ES technology in EM engineering is discussed, and especially the progress of complete ES in electromagnetic compatible (EMC) is introduced.
Ultra-Wideband Design of the Wire Conical Antenna
WANG Qi, HE Qing-qiang
2005, 3(4): 334-337.
Using the wire construction technique, a conical monopole antenna is fabricated. With the method of moments, the dependences of the voltage standing wave ratio (VSWR) on the number of the trapezoid wire elements, conical angles, wire radius, etc. are investigated. The calculation and the experiment show that the designed wire conical antenna has the ultra-wideband property and can be used for the engineering.
Devices and Materials
On Zitterbewegung of Electron
WANG Zhi-yong, XIONG Cai-dong, ZHOU Ping
2005, 3(4): 338-341.
Traditionally, all the discussions on zitterbewegung (zbw) of electron are based on relativistic quantum mechanics. In this article, from the viewpoint of quantum field theory and in terms of the creation and annihilation operators as well as the polarization vectors of spin-1 field, a more detailed description and some new perspectives for zbw are obtained. Especially, it is shown that zbw arises from a to-and-fro vacuum polarization that occurring in the neighborhood of electron; the zbw vectors form a vector triplet with total spin projections 0 and 1 in the direction of the momentum of electron, respectively; the macroscopic velocity of the vacuum medium vanishes in all inertial systems.
Automation and Mechatronics Technologies
Adaptive Trajectory Tracking Control of Wheeled Mobile Robots with Nonholonomic Constraint
LI Jian-hua, WANG Sun-an
2005, 3(4): 342-347,353.
A mobile robot is one of the well-known nonholonomic systems. In this paper, a new adaptive tracking controller for the kinematic model of a nonholonomic mobile robot with unknown parameters is proposed. Stability of the rule is proved through the use of a Liapunov function. The artificial electrostatic field cooperates with error posture in steering in the controller. At last, this method is implemented on the simulations and the wheeled mobile robot. Results show the effectiveness of the controllers.
Controller Design for a Teleoperation System with Time Delay
SHE Jun, JIAO Shou-jiang, LUO Xiao-yuan, GUAN Xin-ping
2005, 3(4): 348-353.
A robust controller design method is presented to guarantee the stability and zero tracking error for teleoperation system with time delay. Through choosing appropriate master and slave parameters, extended state equation about master and master-slave error is achieved, which can be analyzed by using time delay knowledge. Thus delay-independent and delay-dependent criteria are derived in terms of the Lyapunov stability theorem, control parameters are obtained by the feasible of linear matrix inequalities. Experimental results show the validity of these approaches and the performance of master and slave manipulators with delay variations is analyzed.
A New Robust Stabilization Analysis Result for Uncertain Systems with Time-Varying Delay
WANG Zhong-sheng, WANG Dong-yun, LIAO Xiao-xin
2005, 3(4): 354-356.
The robust stabilization problem for uncertain systems with time-varying delay has been discussed. A new sufficient criterion is obtained to guarantee the closed-loop system robust stabilizable. The controller gain matrix is included in a Hamiltonian matrix. The Hamiltonian matrix can be constructed by the boundedness of the uncertainties. Some examples are given to illustrate the feasibility of the criterion.
Development of Laser-Based Handheld Aerosol Particle Counter
CHEN Chang, LI Hui
2005, 3(4): 357-359.
The JC-CA300 handheld Aerosol particle counter is designed and developed based on light scattering principle. The JC-CA300 counter is composed of optical sensor, DSP component and microprocessor unit. The hardware architecture is designed in compact style by SMT IC chips. The whole counter weight is less than 2 pounds. With 32K RAM space, the JC-CA300 can store 500 sampling records and support standard printer and communicate with a computer through RS232 interface. Based on experimental results, the main performance of JC-CA300 is better than that of the ARTI'S HHPC-6 instrument.
Neural Networks and Intelligent Systems
A Periodic Solution of Cellular Neural Networks with Delay
ZHU Pei-yong, SUN Shi-xin
2005, 3(4): 360-363.
It is showed that there is an unique -period solution x(t,*) for a delayed cellular network and its each solution x(t,) converges exponentially to x(t,*) if its each output function is bounded and satisfies Lipschitz condition when all input signals are -periodic functions.
Achieving of Fuzzy Automata for Processing Fuzzy Logic
SHU Lan, WU Qing-e
2005, 3(4): 364-368.
At present, there has been an increasing interest in neuron-fuzzy systems, the combinations of artificial neural networks with fuzzy logic. In this paper, a definition of fuzzy finite state automata (FFA) is introduced and fuzzy knowledge equivalence representations between neural networks, fuzzy systems and models of automata are discussed. Once the network has been trained, we develop a method to extract a representation of the FFA encoded in the recurrent neural network that recognizes the training rules.
Extracting Epileptic Feature Spikes Using Independent Component Analysis
YAN Hong-mei, XIA Yang, LIU Yan-su, LAI Yong-xiu, YAO De-zhong, ZHOU Dong
2005, 3(4): 369-371.
In recent years, blind source separation (BSS) by independent component analysis (ICA) has been drawing much attention because of its potential applications in signal processing such as in speech recognition systems, telecommunication and medical signal processing. In this paper, two algorithms of independent component analysis (fixed-point ICA and natural gradient-flexible ICA) are adopted to extract human epileptic feature spikes from interferential signals. Experiment results show that epileptic spikes can be extracted from noise successfully. The kurtosis of the epileptic component signal separated is much better than that of other noisy signals. It shows that ICA is an effective tool to extract epileptic spikes from patients' electroencephalogram EEG and shows promising application to assist physicians to diagnose epilepsy and estimate the epileptogenic region in clinic.
Antiviral Warrior-APOBEC3G
WU Xiao-xia, MA Yi-cai
2005, 3(4): 372-376.
This paper is to further understand how APOBEC3G can defend the retroviruses and to find new approaches to AIDs (acquired immure deficiency syndrome).The viral infectivity factor (Vif) induces rapid degradation of APOBEC3G by ubiquitination, which is a proteosome-dependent pathway. Precisely speaking, only in the virus-producing cell Vif expression is necessary; in its absence, infection of a subsequent target cell terminates at a postentry step through the action of the human APOBEC3G antiviral mechanism. Vif protein has two domains:one binds to APOBEC3G and the other regulates the degradation of APOBEC3G by a conserved sequence, SLQ (Y/F) LA motif. Recently, the research on Vif has also revealed APOBEC3G is a novel component of innate immune system. In fact, APOBEC3G not only acts in DNA editing to block the replication of retroviruses such as HIV-1, but also is able to defend a wide spectrum of distantly related retroviruses and interferes with HBV through a different mechanism from HIV.
Information Flow Analyzing Based on CPC
ZHANG Zhang, LI Hui
2005, 3(4): 377-379.
The information flow chart within product life cycle is given out based on collaborative production commerce (CPC) thoughts. In this chart, the separated information systems are integrated by means of enterprise knowledge assets that are promoted by CPC from production knowledge. The information flow in RD process is analyzed in the environment of virtual RD group and distributed PDM. In addition, the information flow throughout the manufacturing and marketing process is analyzed in CPC environment.