CIC Filter Theory in DDC and Implementation by Using FPGA

Cascade Integrator Comb(CIC) filter is the main part of the next generation High Frequency (HF) radar. This paper describes the key points of CIC theory in the Digital Down Conversion (DDC) module of a radar receiver, and takes advantage of the high flexibility and high density feature of Field Programmable Gate Array (FPGA) for putting forth to design the CIC filter by using FPGA. This paper provides particular insight into design by FPGA, which has advantages in high speed operation and simply structure. Some important and practical applications are given in this paper. The simulation result proves the validity and veracity. Because we can adjust the parameters freely according to our need, the CIC filter can be adapted to the next generation HF radar. Key words FPGA - DDC - CIC filter - HF radar CLC number TN 47 Foundation item: Supported by the 863 High Technology Project of China(2001AA631050)Biography: MA Zhi-gang(1978-), male, Ph. D candidate, research direction: software radio and EDA design.

Multi-Path Routing and Resource Allocation in Active Network

An algorithm of traffic distribution called active multi-path routing (AMR)in active network is proposed. AMR adopts multi-path routing and applies nonlinear optimizeapproximate method to distribute network traffic among multiple paths. It is combined to bandwidthresource allocation and the congestion restraint mechanism to avoid congestion happening and worsen.So network performance can be improved greatly. The frame of AMR includes adaptive trafficallocation model, the conception of supply bandwidth and its' allocation model, the principle ofcongestion restraint and its' model, and the implement of AMR based on multi-agents system in activenetwork. Through simulations, AMR has distinct effects on network performance. The results show AMRisa valid traffic regulation algorithm.

An Improved Double-Threshold Method Based on Gradient Histogram

This paper analyzes the characteristics of the output gradient histogram and shortages of several traditional automatic threshold methods in order to segment the gradient image better. Then an improved double-threshold method is proposed, which is combined with the method of maximum classes variance, estimating-area method and double-threshold method. This method can automatically select two different thresholds to segment gradient images. The computer simulation is performed on the traditional methods and this algorithm and proves that this method can get satisfying result. Key words gradient histogram image - threshold selection - double-threshold method - maximum classes variance method CLC number TP 391. 41 Foundation item: Supported by the National Nature Science Foundation of China (50099620) and the Project of Chenguang Plan in Wuhan (985003062)Biography: YANG Shen (1977-), female, Ph. D. candidate, research direction: multimedia information processing and network technology.

Wigner Frequency Point Slice Analysis of Superposition Data for Phased-Array Ground Penetrating Radar

According to the frequency property of Phasedarray ground penetrating radar (PGPR), this paper gives a frequency point slice method based on Wigner time-frequency analysis. This method solves the problem of analysis for the PGPR's superposition data and makes detecting outcome simpler and detecting target more recognizable. At last, the analytical results of road test data of the Three Gorges prove the analytical method efficient. Key words phased-array ground penetrating radar - wigner time-frequency analysis - superposition data - object identification CLC number TN 715.7 Foundation item: Supported by the National Nature Science Foundation of China (50099620) and 863 Program Foundation of China (2001AA132050-03)Biography: ZOU Lian (1975-), male, Ph. D candidate, research direction: signal processing.

A Distributed Optimal Scheme Based on Local QoS for Web Service Composition

The goal of web service composition is to choose an optimal scheme according to Quantity of Service （QoS） which selects instances in a distributed network. The networks are clustered with some web services such as ontologies, algorithms and rule engines with similar function and interfaces. In this scheme, web services acted as candidate service construct a distributed model which can＇t obtain the global services＇ information. The model is utilized to choose instances according to local QoS information in the progress of service composition. Some QoS matrixes are used to record and compare the instance paths and then choose a better one. Simulation result has proven that our ~pproach has a tradeoff between efficiency and ~quality.

A Novel Immune System Model and Its Application to Network Intrusion Detection

Based on analyzing the techniques and architecture of existing network Intrusion Detection System (IDS), and probing into the fundament of Immune System (IS), a novel immune model is presented and applied to network IDS, which is helpful to design an effective IDS. Besides, this paper suggests a scheme to represent the self profile of network. And an automated self profile extraction algorithm is provided to extract self profile from packets. The experimental results prove validity of the scheme and algorithm, which is the foundation of the immune model.

New Parallel Interference Cancellation Scheme for DS/CDMA Systems

This paper proposes a new multi-stage parallel interference cancellation scheme by modifying the conventional multi-stage parallel interference canceller (PIC). At each stage, it first converts the interference-cancelled outputs from previous stage into thea prior information, in terms of which the bit mean values are computed and the multi-access interference (MAI) for each user is evaluated, and then an interference cancellation is performed to obtain further interference suppression. To reduce the implementation complexity, we give an approximation expression for bit mean value. The performance over AWGN channel is analyzed and compared to the conventional PIC. The user numberK=7 and spreading factorN=13 are chosen as simulation parameters. The computer simulation results show that the proposed PIC has better performance than the conventional PIC both with 2 interference cancellation (IC) stages, at bit error rate of 10?3, for example, about 3 dB performance gain is obtained by using the proposed PIC. It is also shown that our proposed PIC with 1-stage is superior to the conventional PIC with 2-stage in performance, which is of practical value because PIC with fewer stages can bring about shorter processing delay. Key words CDMA - parallel interference cancellation - multi-access interference CLC number TN 914 Foundation item: Supported by the National Natural Science Foundation of China (69772015)Biography: Xu Guo-xiong (1967-), male, Ph. D candidate, research direction: wireless communication.

Synthetic Aperture Radar Raw Signals Simulation of Extended Scenes

A synthetic aperture radar (SAR) raw signal simulation algorithm for extended scenes is presented. This algorithm is based on the SAR two-dimensional system transform function (STF). To cope with range-variant nature of SAR STF and increase the speed of this algorithms, new formulas for range-variant phase corrections in range-Doppler (RD) domain are developed. In this way, many azimuth lines can be simulated with the same SAR STF. It only needs two-dimensional fast Fourier transform code and complex multiplications. Comparing with time-domain simulation algorithm, it is very simple and thus efficient. Simulation results have shown that this algorithm is accurate and efficient. Key words synthetic aperture radar - raw signal simulation - system transform function CLC number TP 751. 1 Foundation item: Supported by the National Natural Science Foundation of China (40376051)Biography: Sun Jin-yao (1967-), female, Ph. D. candidate, research direction: SAR image simulation and 3D recover for SAR image.

Interleaver Design Method for Turbo Codes Based on Genetic Algorithm

This paper describes a new interleaver construction technique for turbo code. The technique searches as much as possible pseudo-random interleaving patterns under a certain condition using genetic algorithms(GAs). The new interleavers have the superiority of the S-random interleavers and this interleaver construction technique can reduce the time taken to generate pseudo-random interleaving patterns under a certain condition. The results obtained indicate that the new interleavers yield an equal to or better performance than the S-random interleavers. Compared to the S-random interleaver, this design requires a lower level of computational complexity. Key words interleaver - Turbo codes - genetic algorithm CLC number TN 911. 22 Foundation item: Supported by the National Natural Science Foundation of China (60372057) and the Key Open Laboratory on Information Science and Engineering of Railway Transportation Ministry of Beijing Jiaotong University of China (KLISAE-0103)Biography: Tan Ying (1963-), female, Associate professor, Ph. D, research direction: error control coding, analysis and design of wireless communication system.

A Novel RSSE-PSP Equalizer with an Adaptive Pre-Filter

A reduced-state sequence estimation (RSSE) receiver based on per-survivor processing (PSP) in conjunction with an adaptive pre-filter is proposed in this paper. In RSSEPSP, each survivor path holds an estimated value of the channel impulse response (CIR), which is updated by adaptive algorithm during the data transmission. Based on the different estimated channel values of each survivor path, corresponding pre-filters are calculated via the Levinson-Durbin algorithm, which can track the time-varying channel adaptively. Computer simulations indicate that the RSSE-PSP equalizer with the new adaptive pre-filter works much better than those with the prevenient pre-filters in ISI channel.

Design and Implementation of a Wideband HF Channel Simulator

The paper presents a wideband high frequency (HF) channel simulator. The simulation consists of a software simulation of a direct-sequence spread-spectrum (DSSS) HF system with RAKE receiver. The validity of the HF channel simulator is demonstrated by the analysis of the scattering function and example results of the simulator. The performance of DS system under HF channel and noise are also presented. The simulation results and theoretical analysis show that a straightforward DS system may properly mitigate the intersymbol interference (ISI) distortion of the HF channel while perform badly under the HF noise and interference.

Photonic Bandgap Properties of One-Dimensional Photonic Crystal Consisting of Complex Artificial Media

Propagation of electromagnetic waves in one-dimensional (1-D) stratifiedchiral structures is described by the 4X4 transfer-matrix method. The photonic bandgap (PBG)properties in 1-D periodical chiral media are investigated. The relation between PBGand chiralityadmittance has been analyzed. Under proper operating parameters, quite perfect multichannelfiltering properties can be obtained with the periodic structure. The photonic bandgap properties ofone-dimensional layered periodical structures that include of double negative (DNG) medium,so-called backward-wave (BW) medium are investigated. The simulation results show that the width ofthe PBG in the structure composed of chiral medium and BW medium is larger then that composed ofchiral medium and usual medium. Our analysis has shown that the usage of the negative material makesit possible to dramatically widen the band gap of one-dimensional photonic crystal.

Network Fault Diagnosis Using DSM

Difference similitude matrix (DSM) is effective in reducing information system with its higher reduction rate and higher validity. We use DSM method to analyze the fault data of computer networks and obtain the fault diagnosis rules. Through discretizing the relative value of fault data, we get the information system of the fault data. DSM method reduces the information system and gets the diagnosis rules. The simulation with the actual scenario shows that the fault diagnosis based on DSM can obtain few and effective rules. Key words computer networks - data reduction - fault management - difference-similitude matrix CLC number TP 393 Foundation item: Supported by the National Natural Science Foundation of China (90204008)Biography: Jiang Hao (1976-), male, Ph. D candidate, research direction: computer network, data mine.

Application of ESPRIT in Broad Beam HF Ground Wave Radar Sea Surface Current Mapping

HF surface wave radar system OSMAR2000 is a broad-beam sea-state detecting radar. ESPRIT (Estimation of Signal Parameters via Rotational Invariance Technique) algorithm is proposed to apply in DOA (direction of arrival) determination of sea echoes. The algorithm of ESPRIT is briefly introduced first. Then discussions are made on the technique for application in the OSMAR2000 framework. Numerical simulation results are presented to demonstrate the feasibility of radial current mapping based on this method. The algorithm manifests significant performance and computational advantages compared with that of MUSIC. Data acquired by OSMAR2000 are processed to give radial current map and the synthesized vector currents are compared with the in-situ measurement with traditional means. The results show the validity of ESPRIT application in DOA determination for broad-beam radar. Key words HF ground wave radar - sea surface current - ESPRIT - MUSIC CLC number TN 911.72 - TN 958.95 Foundation item: Supported by the National Natural Science Foundation of China (60201003) and the National High Technology Development 863 Program of China (863-818-01-02)Biography: Liu Dan-hong (1976-), female, Master candidate, research direction: radar signal processing.

Simulation of the RCS Range Resolution of Extremely Large Target

The high frequency hybrid technique based on an iterative Physical Optics(PC)) and the method of equivalent current (MEC) approach is developed for predicting rangeresolution of the Radar Cross Section (RCS) in the spatial domain. We introduce the hybrid highfrequency method to simulate range resolution of the extremely large target in the near zone. Thispaper applies this method to simulate the range resolution of the two 1 m X 1 m plates and the ship.The study improves the speed of simulatingthe range resolution of the extremely large target and isprepared for the application of the extrapolation and interpolation in the spatial domain.

Implementation of Transaction Level AMBA Bus Models Using SystemC

This paper deals with how to implement AMBA bus transaction level modeling in SystemC. There are two main techniques used in the whole modeling process, which consist of starting the platform modeling at the transaction level and using the uniformed modeling language— System C. According to the concepts of interface, port and hierarchical channel introduced in SystemC 2.0, the system of master-channel (AMBA bus) slave is created as the architecture of the AMBA bus transaction level model, which can make it more extendable. The port and interface classes of the model that are prone to program are defined in accordance with the SoC hierarchical design methodology. In addition, method calls, not signal communication, are used between different modules in the model, so the higher-level abstraction is achieved and the simulation performance is improved. The AMBA bus transaction level model is analyzed and certified by simulation experiment, and proved to be completely compliant to the AMBA specification 2.0. Key words AMBA - transaction level - SystemC - SoC CLC number TP 393 Foundation item: Supported by the National High Technology Development 863 Program of China (2002AA1Z1490)Biography: He Zhen (1979-), male, Master candidate, research direction: system level modeling in SoC hardware/software co-design.

Fast Dating of Yongzheng Copper Coins in Tsing Empire by SEM-EDS

Twenty Yongzheng copper coins were fast dating by X-ray energy dispersive spectrometer with scanning electron microscope (SEM-EDS) according to official ingredient. The 20 coins were classified in two groups according to the results. Group 1 represents the coins minted before AD 1 728 and group 2 represents the coins minted after AD 1 728. At concentration range (0.00%–5.13%), the distribution of lead is not homogeneous in the coins, and the largest diameter of lead inclusion is less than 15 μm. The official fineness degrade is supported. Key words archaeometry - Yongzheng coins - dating - SEM-EDS CLC number O 69 - K 854.2 Foundation item: Supported by the Project of Instrument Upgraded of Ministry of Science and Technology of ChinaBiography: Lei Jun-feng (1975-), male, Ph. D, research direction: numismatic archaeology and instrument analysis.

Research on Data Combination for Phased-Array Ground Penetrating Radar

To resolve the data combination of Phased-array Ground Penetrating Radar (PAGPR), we first build a model of PAGPR and a layered model, and then a new data combination algorithm is presented based on it. This method calculates time delay of multi-receivers, basing on the signal of the nearest receiver, then shifts other signals and adds them up, and gets one signal at last. It has been proved that this method can restrain noise, multiple waves, clutter waves and improve the precision of time location. In the end, an example is given to prove the method's efficiency.

Application of Two Migration Methods for Ground Penetrating Radar Data

This paper begins with the basic principles of finite-difference migration and diffraction scan migration, and then compares the processing results of the practical ground penetrating radar GPR data with these two migration methods. It is illustrated that migration can refocus the reflecting points in radar record to their true spatial location and provide the foundation for interpretation, thus improving precision of interpretation of (GPR) profiles. Key words finite-difference wave equation migration - diffraction scan migration - GPR - migration image CLC number TN 715.7 Foundation item: Supported by the National Natural Science Foundation of China (50099620) and the National High Technology Development 863 Program of China (2001AA132050-03)Biography: Shi Jing (1979-), female, Master candidate, research direction: signal processing

Design and Implementation of A Dynamic Content Cache Module for Web Server

Web offers a very convenient way to access remote information resources, an important measurement of evaluating Web services quality is how long it takes to search and get information. By caching the Web server’s dynamic content, it can avoid repeated queries for database and reduce the access frequency of original resources, thus to improve the speed of server’s response. This paper describes the concept, advantages, principles and concrete realization procedure of a dynamic content cache module for Web server. Key words dynamic content caching - network acceleration - apache module CLC number TP 393.09 Foundation item: Supported by the Science Committee of WuhanBiography: LIU Dan (1980-), male, Master candidate, research direction: high speed computer network, high performance server clusters system.