Sep 2009, Volume 4 Issue 3
    

  • Select all
  • REVIEW ARTICLE
    Xuesong LU, Xuegong ZHANG

    With the development of microarray technology, more and more microarray-based oncology studies have been carried out. Huge amounts of data and the complexity of cancer mechanisms make data analysis methods a much more important part of these studies. In this article, we will mainly focus on the pattern recognition methods used in oncology studies. According to the availability of sample information, the unsupervised methods and supervised methods are reviewed separately. Finally, some possible future directions are proposed.

  • RESEARCH ARTICLE
    Xiaojun SUN, Zili DENG

    The white noise deconvolution or input white noise estimation problem has important applications in oil seismic exploration, communication and signal processing. By combining the Kalman filtering method with the modern time series analysis method, based on the autoregressive moving average (ARMA) innovation model, new distributed fusion white noise deconvolution estimators are presented by weighting local input white noise estimators for general multisensor systems with different local dynamic models and correlated noises. The new estimators can handle input white noise fused filtering, prediction and smoothing problems, and are applicable to systems with colored measurement noise. Their accuracy is higher than that of local white noise deconvolution estimators. To compute the optimal weights, the new formula for local estimation error cross-covariances is given. A Monte Carlo simulation for the system with Bernoulli-Gaussian input white noise shows their effectiveness and performance.

  • RESEARCH ARTICLE
    Yujie PEI, Hongbo WANG, Shiduan CHENG

    Congestion may decrease throughput and transfer efficiency of network, and lead to serious degradation of quality of service (QoS) acquired by end users. Present routing adjustment methods against congestion mostly consider single-point congestion. They cannot deal with multi-point congestion. This paper presents a probability-based routing adjustment algorithm, which solves the interference problem when several flows are adjusted simultaneously. While multiple points in the network are being or about to be congested, several key flows are rerouted by this algorithm at the same time to make traffic distribution more reasonable so as to avoid congestion. Meanwhile, the algorithm in this paper confines the path length of key flows to avoid QoS reduction due to overlength of key flows. Simulation shows that this method, compared with present algorithms, maintains better load balance and path length. Therefore it effectively increases the throughput of the network.

  • RESEARCH ARTICLE
    Hongjun WANG, Guangguo BI

    With the progress of research on cognitive radio in ultra-wideband (UWB) open frequency-band, a joint detection algorithm integrating the energy and bi-spectrum detection is proposed in detail for non-Gaussian signal detection from Gaussian noise. The performance of the algorithm was evaluated by simulation, the result of which indicates that the joint detection not only solves the problem of the signal detection in low signal-to-noise ratio (SNR) but also improves the operational speed and the detection probability. Thus, the joint detection algorithm has definite prospect in practice.

  • RESEARCH ARTICLE
    Hangyang DAI, Hongbing XU

    For security services in wireless sensor networks, key management is a fundamental building block. In this article, we propose a triangle-based key predistribution approach and show that it can improve the effectiveness of key management in wireless sensor networks. This is achieved by using the bivariate polynomial in a triangle deployment system based on deployment information about expected locations of the sensor nodes. The analysis indicates that this scheme can achieve higher probability of both direct key establishment and indirect key establishment. On the other hand, the security analysis shows that its security against node capture would increase with a decrease of the sensor node deployment density and size of the deployment model and an increase of the polynomial degree.

  • RESEARCH ARTICLE
    Yanhua YU, Jun WANG, Xiaosu ZHAN, Junde SONG

    The mode of telecommunications network management is changing from “network oriented” to “subscriber oriented”. Aimed at enhancing subscribers’ feeling, proactive performance monitoring (PPM) can enable a fast fault correction by detecting anomalies designating performance degradation. In this paper, a novel anomaly detection approach is the proposed time series prediction and the associated confidence interval based on multiplicative autoregressive integrated moving average (ARIMA). Furthermore, under the assumption that the training residual is a white noise process following a normal distribution, the associated confidence interval of prediction can be figured out under any given confidence degree 1-α by constructing random variables satisfying t distribution. Experimental results verify the method’s effectiveness.

  • RESEARCH ARTICLE
    Tong ZHANG, Yahui WANG, Anli YE, Jian WANG, Jianchao ZENG

    Within the heat and moisture system that is complex in the air-conditioning rooms of large space building, the existence of delay makes the stability cushion reduced, which thereby makes the estimated parameters more complex. In this paper, particle swarm optimization (PSO) is integrated with least square (LS) to improve least squares (short for PSOLS). LS, optimized by PSO, identifies the heat and moisture system parameters of the existence of delay in the air-conditioning rooms by sampling input and output data. In view of this delay system, the identification is an effective solution to nonlinear system which LS can not identify directly. The simulation results show that PSOLS is quite effective, and its global optimization has great potential.

  • RESEARCH ARTICLE
    Zengliang SHI, Dali LIU, Yu WANG, Xi CHEN, Shiying BAI, Jingwei XU

    Working principles of silicon double P-N junction color sensor are introduced and a color measurement system to distinguish tooth color difference is designed in this paper. This system consists of silicon double P-N junction, a small optical fiber probe, signal process circuit and an MSP430FG439 single-chip system. Small in size, this system can measure different parts of the tooth in a fast and convenient way with high-accuracy. Thus, this system will be very promising in building prosthodontics and tooth fabrication.

  • REVIEW ARTICLE
    Shunshi ZHONG, Zhu SUN, Xiaorong TANG

    The progress in dual-band dual-polarization (DBDP) shared-aperture antennas for the synthetic aperture radar (SAR) application in the last decade is reviewed. Several designs of DBDP SAR antenna arrays are introduced with their main performances, then their comparison is summarized. In addition, some techniques enhancing DBDP antenna performances are presented.

  • RESEARCH ARTICLE
    Chongqing JIAO

    The preliminary design results of a 1-MW, Ku-band gyrotron traveling wave amplifier (gyro-TWA) are presented. Operating at the second cyclotron harmonic of the TE11 mode, the amplifier characterizes good stability even in the case of no distributed losses loaded, which could potentially allow it to be operated at high average power. Large signal simulation shows that the amplifier can generate a saturated peak power of about 1 MW with efficiency of 26.6%, gain of 31 dB, and 3-dB bandwidth of about 1 GHz when driven by a 100 kV, 40 A electron beam with 5% axial velocity spread.

  • RESEARCH ARTICLE
    A. GOURBI, M. BRAHAMI, A. TILMATINE, P. PIROTTE

    When it rains, electric power transmission lines start vibrating due to corona effect. This type of vibration is known as “corona-induced vibration”. The aim of this paper is to elaborate a mathematical model for numerical simulation of the corona-induced vibration, with consideration of the influence of the magnitude and the polarity of the electric field on the conductor surface. Finite element method was employed to develop the numerical model, and the finite difference method was used for the time discretisation. The moment of application of the corona-induced force is evaluated using the resultant vertical force applied to a water drop, suspended under a high voltage conductor. Some experimental results of other authors are exploited to evaluate the precision of the simulation and the validation of numerical results.

  • RESEARCH ARTICLE
    Yuhui HE, Yuning ZHAO, Chun FAN, Xiaoyan LIU, Ruqi HAN

    This paper studies the elastic deformation field in lattice-mismatched Ge-Si core-shell nanowires (NWs). Infinite wires with a cylindrical cross section under the assumption of translational symmetry are considered. The strain distributions are found by minimizing the elastic energy per unit cell using finite element method. This paper finds that the trace of the strain is discontinuous with a simple, almost piecewise variation between core and shell, whereas the individual components of the strain can exhibit complex variations. The simulation results are prerequisite of strained band structure calculation, and pave a way for further investigation of strain effect on the related transport property simulation.