Table of Content

20 December 2007, Volume 13 Issue 6

Previous Issue    Next Issue

Articles

Quantum Light Memory Using Quantum Dot Spins in Microdisk Cavity

XIONG Jin;ZHENG Yi-cong;ZENG Gui-hua

2007, 13(6):  647-652 . 

Asbtract ( 2725 )   PDF (785KB) ( 991 )  

Related Articles | Metrics

This paper studies a solidstate quantum circuit in which an ensemble of self-assembled quantum dots in a microdisk cavity is served as longlived quantum light memory. It is shown that, via the laser coupling Raman process, coherent transfer between the light field (qubits) and the ensemble spin states of the quantum dots is efficient and fast. Coherence properties of the system are analyzed, which enables one to obtain a long coherence time. It can be used as a storage cell with practical applications in the future.

Carrier Phase Recovery for Turbo-Coded System with PSAM

SHI Hai;WEN Ji-ni;WU Zhuo

2007, 13(6):  653-656 . 

Asbtract ( 2453 )   PDF (421KB) ( 862 )  

Related Articles | Metrics

A carrier phase recovery scheme suited for turbocoded systems with pilot symbol assisted modulation (PSAM) in Rayleigh fading channels is proposed in this paper. This scheme involves Rayleigh fading channel estimation with PSAM and utilizes the joint phase recovery and turbodecoder to aid the iterative carrier phase estimation. Simulation results show that the proposed method with small system expense can significantly improve the performance of carrier phase recovery for turbo-coded systems in Rayleigh fading channels.

Design of Ultra-Low Power Wireless Wake-on-Radio Transceiver

ZHANG Xue-fan;SHEN Ming-hua

2007, 13(6):  657-662 . 

Asbtract ( 2996 )   PDF (729KB) ( 937 )  

Related Articles | Metrics

Power consumption is a serious challenge to designers of RF transceivers for use in distributed wireless sensor networks since the transceiver must always be powered on for possible incoming packets. In this paper, we propose to combine optimization of the integrated transceiver hardware and the medium access control protocol. By analyzing key factors of lowpower hardware architecture and using a simplified media access control protocol for wake-on-radio, a low power RF transceiver is designed. Test results show that power consumption of the proposed RF transceiver is more than 10 times lower than conventional equipment, satisfying the practical requirements.

Enhancement of Video Coding Quality in Low Bit Rate Channel

HAN Jun;SHAO Zhi-yi;SONG Hai-hua

2007, 13(6):  663-668 . 

Asbtract ( 2909 )   PDF (712KB) ( 1032 )  

Related Articles | Metrics

Mobile phones capable of receiving TV programs are expected to appear in the market. This paper discusses a method for enhancing video coding quality in a low bit rate channel aimed at mobile TV applications. In the early stage,
quantization parameter (QP) is adjusted to make the video stream fit the bandwidth. When network jam occurs, the bandwidth decreases. A dynamic frame discard strategy is proposed at the encoder is proposed, which discards the frames correlated to others based on scene change detection, and uses bilinear temporal interpolation to estimate the missing frames in the decoder. We obtain better video quality to meet requirements of the wireless channel bandwidth. Experiments show effectiveness of the method.

Cesaro Means of Fourier Series in Designing Planar
Lightwave Circuit-Type Lattice-Form Interleaver

ZHANG Juan

2007, 13(6):  669-673 . 

Asbtract ( 2322 )   PDF (555KB) ( 728 )  

Related Articles | Metrics

Based on the Cesaro means of Fourier series and the mathematical equivalence between structural parameters of the latticeform and the birefringent interleavers, a new method for designing planar lightwave circuit (PLC)-type lattice-form interleavers is proposed. All structural parameters can be obtained with a single step of simple analysis and solution to a set of simple equations. As an example, a 25 GHz 3latticecascaded PLCtype interleaver is designed. The resulting channel isolation is significantly improved compared to those obtained in the literature, indicating that the method can meet stringent design requirements of the DWDM system.

IP Core Design Based on 2D-Mesh Multi-processor System

ZHANG Jun-jie;MAO Qun-ling;WANG Yan-fang

2007, 13(6):  674-678 . 

Asbtract ( 2297 )   PDF (601KB) ( 826 )  

Related Articles | Metrics

This paper presents an algorithm for 2D-mesh multiprocessor system that is deadlock free and non-adaptive. A new protocol based on 2D-mesh communication is proposed. Simulation results verify the theoretical analysis.

Regulated AC Power Supply for Base Station Using Double PWM

JIANG You-hua;FANG Yong;GU Sheng-jian

2007, 13(6):  679-683 . 

Asbtract ( 2146 )   PDF (595KB) ( 726 )  

Related Articles | Metrics

A novel regulated AC power supply unit for base stations using double PWM is presented in this paper. The main circuit and its principle of operation are introduced, and the power flow analyzed. Compared with conventional regulated AC power supply, the proposed method has high efficiency and faster response, and does not use a charcoal brush therefore is free of mechanical fault. It also avoids the cyclecurrent fault existing in AC voltage regulators using SCR. Simulation and experiments show that the proposed scheme is feasible.

Four Differential Polarization Shift Keying

WANG Ji-dong;WANG Chun-hua;LUO Fan;HUANG Zhao-ming

2007, 13(6):  684-687 . 

Asbtract ( 2543 )   PDF (396KB) ( 840 )  

Related Articles | Metrics

In this paper, optical communication using quaternary differential polarization shift keying is proposed, which is immune to random fluctuation in the state of polarization (SOP) of the optical signals propagating through a single-mode fiber. Relationship is established in the transmitter using differential coding between the difference in SOPs of the optical signals in consecutive symbol periods and the input symbol of the differential encoder. In the receiver, Stokes vectors are extracted from the optical signals in two consecutive symbol periods. Dot product of the two vectors is then obtained so that the transmitted sequence recovered. The dot multiplication can effectively eliminate the effect of random fluctuation in the SOPs of optical signals on the performance of communication system.

Design of a Time-Domain Equalizer for OFDM System

WANG Yong;CHEN Hui-min;JIN Yan-liang;GU Lin

2007, 13(6):  688-691 . 

Asbtract ( 2827 )   PDF (468KB) ( 881 )  

Related Articles | Metrics

In this paper a time-domain equalizer (TEQ) in an OFDM system is designed. With preamble sequences as the training sequences of TEQ, it is no longer necessary to use additional training sequences in the system. Therefore overhead of the system is reduced. Simulation results show that the performance of the TEQ is better than linear equalizer (LE) and decision feedback equalizer.

Software Compensation for Wavelength Shift in Coupled -Fiber Optic Temperature Sensor

LU Jun;PANG Fu-fei;WANG Ting-yun

2007, 13(6):  692-695 . 

Asbtract ( 2397 )   PDF (502KB) ( 906 )  

Related Articles | Metrics

The mechanism of coupled evanescent wave temperature sensors is analyzed with the theory of strong coupling. A temperature detection system based on a micro-controller is designed. To eliminate circuit noise, hardware and software filters are introduced to improve stability of the temperature detection system. The optical spectrum of LD light sources will change with the ambient temperature. This will cause instability and poor precision of the detected temperature due to the relationship between wavelength and the coupling ratio. To deal with this problem, the microcontroller's embedded temperature sensor is proposed to use to compensate for the errors in the temperature detected by the optic fiber sensor. Experiments show that the temperature precision can reach ±1 ℃.

Energy Efficiency of STBC-Encoded Cooperative Transmission-System in Wireless Sensor Networks

YU Jie;CHEN Hui-min;JIN Yan-liang

2007, 13(6):  696-698 . 

Asbtract ( 2961 )   PDF (368KB) ( 755 )  

Related Articles | Metrics

STBCencoded cooperative transmission system in wireless sensor networks and its energy efficiency are investigated. A criterion for performance comparison between STBCencoded cooperative transmission and single transmission is proposed. The threshold of transmit power in cooperative transmission is calculated for energylimited wireless sensor networks. Simulation results demonstrate that the proposed threshold of transmitted power can minimize the overall networktransmission power with a certain outage probability.

Implementation of Consistency Algorithm for Dynamic 
Reconfiguration in Distributed System

CAO Min;ZHANG Wen

2007, 13(6):  699-704 . 

Asbtract ( 2437 )   PDF (723KB) ( 847 )  

Related Articles | Metrics

Dynamic reconfiguration of component-based software has been attracting increasing research interests. It is important to ensure consistency while dynamically reconfiguring a distributed system. This paper proposes a consistency algorithm for dynamic reconfiguration of component-based distributed software based on the transaction and component quiescent state theory. The improved method adopts a waiting mechanism to properly ensure consistency of dynamic reconfiguration in the model. Practice shows that the algorithm is feasible.

Database Cluster Preprocessing with Principal Component Extraction

XU Jun;XIA Jiao-xiong;LI Qing

2007, 13(6):  705-710 . 

Asbtract ( 2316 )   PDF (746KB) ( 1134 )  

Related Articles | Metrics

According to the principle of least relativity of the data object, database cluster preprocessing with principal component extraction (DCP-PCE) is proposed to reduce dimension of a high dimensional system. Cluster extraction is carried out with hierarchical principal component analysis. The projection on the most differentiation of the data object is defined as principal component, which can be proved to include all the original information of the data object sets. With the DCP-PCE, comprehensive coverage of variables and lower dimension of principal component are solved synchronously, dissimilarity and dimension of the data object sets are decreased, and clustering reduction of the data object sets are reached. By leading the clustering analysis into the preprocessing of data resource on the colleges and universities, the application example is given to illustrate the effectiveness for exploration model.

Session Initiation Protocol Based on Peer-to-Peer Architecture

YE Liang;GU Xun-rang

2007, 13(6):  711-714 . 

Asbtract ( 2431 )   PDF (517KB) ( 861 )  

Related Articles | Metrics

Controlled by the background server, application of the traditional session initiation protocol (SIP) will face risks such as failure of one node server and crash of the whole network due to attack. Meanwhile, user communications are restricted. The SIP application based on peer-to-peer(P2P) can realize user registration, joining, seeking, retrieval and routing. It has advantages of balanced communication load and system robustness. With the evolution from SIP to P2P, reliability and scalability of the SIP network will be improved, making interconnection between traditional communication system and SIP network easier.

A New Approach of Estimating Value at Risk

TANG Lin-jun;WANG Han-xing;

2007, 13(6):  715-719 . 

Asbtract ( 2279 )   PDF (550KB) ( 889 )  

Related Articles | Metrics

As for the sharp-kurtosis and fat-tail characteristics of the money-market yield, a mixed distribution — Laplace and extreme value-II distribution is proposed, which is applied to establish a new model for estimating value at risk (VaR).By demonstrating in the financial market, this new method shows a very high practical value in which return rate has extreme.

Nonparametric Computation of VaR and CVaR 
for a Type of Financial Series

XIE Xiao-heng;HE You-hua

2007, 13(6):  720-725 . 

Asbtract ( 2725 )   PDF (632KB) ( 1016 )  

Related Articles | Metrics

Under the assumption that the yield series is a strictly stationary process, we present an equation satisfied by value at risk (VaR) at time t given historical data and an analytic formula for conditional value at risk (CVaR). We use S&P 500 as an example to discuss how the length of historical data before t affects the estimate of VaR and CVaR at time t . The VaR series obtained with the proposed method and that with the GARCH model are compared. It is found that both results have similar fluctuations, but VaR values of the former is larger and smoother because normality assumption is not used. By using different sample length to estimate CVaR, the proposed method is shown to be more robust.

宋承燕，何幼桦

SONG Cheng-yan;HE You-hua

2007, 13(6):  726-731 . 

Asbtract ( 2525 )   PDF (563KB) ( 956 )  

Related Articles | Metrics

The mixed problem with lower bound for dry inviscid atmospheric circulation equations is discussed. We decompose the problem into two parts: a pure Cauchy problem and a group of integration expressions. We show that such decomposition gives the same solution with the original problem, and discuss wellposedness of the Cauchy problem based on the stratification theory. A necessary and sufficient condition for wellposedness of the original mixed problem is then obtained. A method for obtaining an analytic solution to the wellposed mixed problem is given.

Instability of Inflated Incompressible Thermohyperelastic Spherical Shells

REN Jiu-sheng;CHENG Chang-jun;

2007, 13(6):  732-735 . 

Asbtract ( 2363 )   PDF (447KB) ( 762 )  

Related Articles | Metrics

Instability of asymmetric deformations of an incompressible thermo-hyperelastic spherical shell, subjected to internal pressure, is examined within the framework of finite elasticity. When the inflation pressure is small, the thin-walled shell undergoes a symmetric inflation. But when the inflation pressure is larger than a certain critical value, the thin-walled shell undergoes an asymmetric deformation. One part becomes highly distended while the rest remains lightly inflated and the shell takes up an aspherical shape. But the thick-walled shell always undergoes a symmetric inflation even if the pressure reaches a very high value. A critical thickness for the shell to take an instability deformation is given based on the change regulation of the deformation curves along with its slope. Furthermore, the effect of temperature on the deformation is discussed.

Discrete Portfolio Optimization with Industry Constraints -and Transaction Cost

WANG Guo-xin;SHEN Qiu-ying;SUN Xiao-ling

2007, 13(6):  736-740 . 

Asbtract ( 2311 )   PDF (584KB) ( 907 )  

Related Articles | Metrics

We consider the discrete single-factor portfolio selection model with industry constraints and concave transaction cost. This model is a nonlinear integer programming problem. A hybrid branch-and-bound method based on Lagrangian relaxation and continuous relaxation is proposed for this model. Computational experiments are carried out with data both from the realworld stock market and generated randomly.

Analytical Approach of Soybean Isoflavones and Its Evaluation

GU Jian-ming;PAN Chun-yun

2007, 13(6):  741-746 . 

Asbtract ( 2667 )   PDF (566KB) ( 1158 )  

Related Articles | Metrics

Soybean isoflavones were determined with a single-wave-length method, a three-wave-length method and HPLC. Singlewavelength method (y=7.431 7x-0.055 6,R2=0.999 8) and three-wave-length method (y=32.432x+0.048 8, R2=0.998 1) were used conveniently for total isoflavones. HPLC (genistin, y=1 828.6x-96.467, R2=0.996 4; daidzin, y=1 795.4x-420.67, R2=0.9953) was used for single isoflavone, which was complicated. Accuracy and precision of the three methods in a descending order is HPLC, three-wave-length method, and single-wave-length method.

Different Conditions of Sorghum Seed's Kafirin Extraction

WANG Wei;YIN Li-ping;CHEN Qin

2007, 13(6):  746-750 . 

Asbtract ( 2681 )   PDF (577KB) ( 836 )  

Related Articles | Metrics

Effects of different reagents, dosages, concentrations, and reduction reagent concentrations on kafirin extraction from -Sorghum bicolor-were investigated. Measurements of protein concentration and the sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE) showed that 60% τbutanol plus 4% DTT at a sample-weight to extraction-solution ratio of 1∶8 (g/mL) was optimum for kafirin extraction. Other sorghum species' alcoholsolute protein (prolamin) were extracted under this condition. It is concluded that, by studying the protein “fingerprint”, different sorghum species can be discriminated from each other.

Protective and Repairing Effect of Crataegus pinnatifida Compounds 
on oxLDL Induced Damages of HMEC

HE Qiu-yan;WENG Xin-chu

2007, 13(6):  751-756 . 

Asbtract ( 2891 )   PDF (658KB) ( 1033 )  

Related Articles | Metrics

This paper studies extracts and pure compounds from Crataegus pinnatifida and their protection and repair effects on oxidized low-density lipoprotein(oxLDL) induced damages of Human Mammary Epithelial Cells (HMEC). Three compounds were isolated from petroleum ether extract and chloroform extract by silica gel column chromatography. Daucosterol, ursolic acid, βsitosterol were identified by melting points, infrared and nuclear magnetic resonance spectra and mass spectra. Results show that different solvent extract and Lovastatin between 3.12 and 25 μg/mL have protective effects to oxidation damage cells. Daucosterol has stronger repairing effect than Lovastatin between 6.25 and 12.5 μg/mL. Ursolic acid has similar repiring effect to Lovastatin at concentration range from 0.39 to 3.12 μg/mL.