Doherty射频功率放大器研究与实践

在分析经典Doherty放大器工作原理基础上,对主从放大器使用不同的漏极偏置电压和电路匹配,设计出一种新型Doherty功率放大器,分析了该结构对于效率和线性化的影响.以飞思卡尔公司的MRF6S20010N功放模型,利用ADS2008对放大器进行静态工作点选取,源负载网络匹配和微带线的计算.结果表明这种功率放大器不但能够提高性能指标,还增强了放大器的稳定性.     

A novel mutual authentication and key agreement protocol based on NTRU cryptography for wireless communications

INTRODUCTION Wireless communications is advancing rapidly in recent years. After 2G (e.g. GSM) widely deployed in the world, 3G mobile communication systems are spreading step by step in many areas. At present, some countries have already launched investigations beyond 3G (B3G) and 4G. Along with the wireless communications’ rapid development, the secure ac-cess authentication of the users within wireless net-works is becoming very critical, and so, more and more attention is focused…     

基于手机短信的课堂应答系统设计与实现

课堂应答系统(CRS)在现代课堂教学中越来越受到人们的关注。文章给出了一种基于手机短信的课堂应答系统设计方案。它具有成本低,使用方便,功能丰富等特点。方案中核心硬件是一台专用短信接收设备,它结合了ARM单片机与短信收发模块M22,具有丰富的计算机接口,能够应用在各种多媒体教室中。该系统在实际课堂教学中得到了应用,能够满足课堂即时互动教学的要求,提高了教学效果。学生积极参与课堂应答系统教学。     

新型客车磁流变缓速器制动力计算与仿真

随着汽车工业的进步,商用汽车逐步向高速及大型化发展,制动安全问题日益突出。安装辅助制动装置是实现大型车辆安全制动的重要途径之一。文章分析传统电涡流缓速器及液力缓速器优缺点,设计一种新型的单盘型客车磁流变缓速器。该缓速器在挤压-剪切混合模式下工作;以磁流变液（MRF）的流变特性为基础,推导该缓速器制动力矩计算公式,并在MATLAB环境下对该制动力矩公式进行仿真和分析,结果显示客车磁流变缓速器制动力矩主要与磁场强度大小有关,与转速和磁流变液间隙厚度关系很小。     

基于MEMS和GSM模块远程监护的实验和研究

提出了基于MEMS和GSM短信沟通平台的检测人体跌倒、自动发送手机短信报警以及紧急呼救的智能监护系统,以实现对居家老人的远程监护和突发意外的及时警报。系统由三大模块组成,其中采集模块、通讯模块和控制模块分别为SIEMENS TC35模块和MMA7260QT加速度传感器以及低功耗单片机STC12LE5204AD,采用AT指令程序实现单片机控制GSM模块自动发送跌倒求救短信。该系统较一般检测算法不同:对人体进行动静态姿势分类,自动检测是否进入省电模式并启用随时唤醒机制;预设的紧急报警按钮使用户能够及时自主求救。实验证明,基于MEMS和GSM的老人监护系统能够及时有效地对居家老人进行可靠监护,对保障老人生命安全具有重要应用意义。     

Parameters selection in gene selection using Gaussian kernel support vector machines by genetic algorithm

INTRODUCTION Recent techniques based on oligonucleotide or cDNA microarrays allow the expression level of thousands of genes to be monitored in parallel (Golub et al., 1999). A critically important factor for cancer diagnosis and treatment is the reliable prediction of tumor progression. A remarkable advance for mo- lecular biology and for cancer research is cDNA mi- croarray technology. cDNA microarray datasets havea high dimensionality corresponding to the large number of genes monit…     

基于核方法的改进可能聚类模型

A novel model of fuzzy clustering using kernel methods is proposed. This model is called kernel modified possibilisticc-means (KMPCM) model. The proposed model is an extension of the modified possibilistic c-means (MPCM) algorithm byusing kernel methods. Different from MPCM and fuzzy c-means (FCM) model which are based on Euclidean distance, theproposed model is based on kernel-induced distance. Furthermore, with kernel methods the input data can be mappedimplicitly into a high-dimensional feature space where the nonlinear pattern now appears linear. It is unnecessary to docalculation in the high-dimensional feature space because the kernel function can do it. Numerical experiments show thatKMPCM outperforms FCM and MPCM.     

Robust model predictive control for discrete uncertain nonlinear systems with time-delay via fuzzy model

INTRODUCTION In recent years, research on nonlinear model predictive control has attracted significant attention because most practical processes are nonlinear. In industry process control, model predictive controllers based on linear models (LMPC) are often used to control nonlinear systems. When the operating con- ditions undergo significant changes, the performance of LMPC can deteriorate drastically. Under such conditions, predictive control based on nonlinear models (NMPC) shoul…     

Exponential synchronization of general chaotic delayed neural networks via hybrid feedback

This paper investigates the exponential synchronization problem of some chaotic delayed neural networks based on the proposed general neural network model, which is the interconnection of a linear delayed dynamic system and a bounded static nonlinear operator, and covers several well-known neural networks, such as Hopfield neural networks, cellular neural networks （CNNs）, bidirectional associative memory （BAM） networks, recurrent multilayer perceptrons （RMLPs）. By virtue of Lyapunov- Krasovskii stability theory and linear matrix inequality （LMI） technique, some exponential synchronization criteria are derived. Using the drive-response concept, hybrid feedback controllers are designed to synchronize two identical chaotic neural networks based on those synchronization criteria. Finally, detailed comparisons with existing results are made and numerical simulations are carried out to demonstrate the effectiveness of the established synchronization laws.     

A novel face recognition method with feature combination

INTRODUCTION Automatic face recognition has become a very active research area in the last decade due to the new interest in, and need for, surveillance and security, telecommunication and digital libraries, hu-man-computer intelligent interaction, and smart en-vironments. The small sample size (SSS) problem is often encountered because the number of the samples is much smaller than the dimension of the sample space in face recognition. It results in the singularity of the within-class …     

纯分析信号算法及其改进

纯分析信号(NAS)是一种即可用来评价矩阵数据的定量分析结果，又可以直接用来对矩阵数据进行定量分析的化学计量学方法．基于纯分析信号的思想建立起来的混合线性分析(HLA)和扩展混合线性分析(HLAE)可适用于不同的情况．HLA方法在建模时需要同时得到待测物质准确的浓度和纯谱信息．我们发展的HLAE是对HLA的扩展，不需用到体系组份的纯谱信息，利用已知物质的浓度信息构造投影矩阵用来提取体系背景信息，然后又用浓度信息和背景信息构造该物质的校正矢量，HLAE对模拟体系和实际体系的分析都取得了比HLA、PLS更好的结果。     

A novel dependency language model for information retrieval

This paper explores the application of term dependency in information retrieval (IR) and proposes a novel dependency retrieval model. This retrieval model suggests an extension to the existing language modeling (LM) approach to IR by introducing dependency models for both query and document. Relevance between document and query is then evaluated by reference to the Kullback-Leibler divergence between their dependency models. This paper introduces a novel hybrid dependency structure, which allows integration of various forms of dependency within a single framework. A pseudo relevance feedback based method is also introduced for constructing query dependency model. The basic idea is to use query-relevant top-ranking sentences extracted from the top documents at retrieval time as the augmented representation of query, from which the relationships between query terms are identified. A Markov Random Field (MRF) based approach is presented to ensure the relevance of the extracted sentences, which utilizes the association features between query terms within a sentence to evaluate the relevance of each sentence. This dependency retrieval model was compared with other traditional retrieval models. Experiments indicated that it produces significant improvements in retrieval effectiveness.     

磁流变液阻尼器设计与性能测试

自动化生产中,自动检测设备的使用越来越广泛,为保证检测精度,这类设备都需要控制气动和电动振动对检测的干扰和影响．为此本文设计了MRF可控阻尼器及可调振动滑台装置,总结基于MRF力学模型和磁路设计模型,设计MRF阻尼器的经验;基于NI数字化测试系统检测MRF阻尼器控制移动滑台振动的效果．实验结果证实MRF阻尼器能快捷方便地调节阻尼、高精度控制移动滑台的振动,MRF阻尼器振动控制装置具有教学实用价值．     

Local curve fitting based Lagrange multiplier selection for Id-slice in multi-view video coding

The rate and distortion of Id-slice do not fit the globally linear relationship on a logarithmic scale. Lagrange multiplier selection methods based on the globally linear approximate relationship are neither efficient nor optimal for multi-view video coding (MVC). To improve the coding efficiency of MVC, a local curve fitting based Lagrange multiplier selection method is proposed in this paper, where Lagrange multipliers are selected according to the local slopes of the approximate curves. Experimental results showed that the proposed method improves the coding efficiency. Up to 2.5 dB gain was achieved at low bitrates.     

基于马尔可夫随机场的图像分割方法研究

在计算机视觉和图像处理等相关领域的Markov(Markov Random Field,即马尔可夫随机场)引入概率这个概念后可以很好地描述图像中各像素间由于处于不同位置而形成的一些特性.主要研究了基于MRF的一种模型——条件随机场CRFs(Conditional Random Fields)模型及其在图像分割中的应用.     

在视频对象平面生成中使用细胞神经网络进行初始对象的分割

1　Introduction　MPEG 4videocodingstandard providesobject basedfunctionalitiesbyintroducingtheconceptofvideoobject plane (VOP) .Withtheextractionofvideoobjectsandallocatingdifferentnumberofbitsordifferentframe ratesfordifferentobjects ,thestan dardcansupportobject basedscalabilitythatisusefulinmanypracticalapplications[1] .However,MPEG 4alwaysassumesthatthevideocontentstobecodedarewellrepresentedinvideoobjectswithoutmandatinganyspecifictechniques;sovideoobjectsegmentationbecomesanimportant…     

Application of generalized predictive control in networked control system

INTRODUCTION Networked Control System (NCS) is composed of a central controller and a remote system containing a physical plant, sensors and actuators (Halevi and Ray, 1988; Nilsson, 1998; Walsh et al., 1999a; 1999b; Branicky et al., 2000). The controller and the plant are located at different spatial locations and directly connected through network to form a closed loop control. Fig.1 shows the NCS configuration and the time delay induced by network, where u is the control signal an…     

Voidage measurement based on genetic algorithm and electrical capacitance tomography

INTRODUCTION Two-phase flow exists widely in chemical, pe- troleum and metallurgical industries. The voidage is one of the most important parameters of two-phase flow because the measurement of the voidage is im- portant for safety, environmental protection, energy conservation and quality assurance in industry (Hewitt, 1978; Lin, 1992). Although many voidage measurement methods have been proposed, it is still difficult to measure the voidage due to the complexity of the characteristics o…     

Flat-type permanent magnet linear alternator: A suitable device for a free piston linear alternator

We proposed the flat-type permanent magnet linear alternator （LA） for free piston linear alternators （FPLAs） instead of the tubular one. Using the finite element method （FEM）, we compare these two kinds of LAs. The FEM result shows that the flat-type permanent magnet LA has higher efficiency and larger output specific power than the tubular one, therefore more suitable for FPLAs, and that the alternator design can be optimized with respect to the permanent magnet length as well as the air gap.     

一种基于鲁棒聚类的欠定稀疏源盲分离算法

In underdetermined blind source separation, more sources are to be estimated from less observed mixtures without knowing source signals and the mixing matrix. This paper presents a robust clustering algorithm for underdetermined blind separation of sparse sources with unknown number of sources in the presence of noise. It uses the robust competitive agglomeration (RCA) algorithm to estimate the source number and the mixing matrix, and the source signals then are recovered by using the interior point linear programming. Simulation results show good performance of the proposed algorithm for underdetermined blind sources separation (UBSS).