Design of nuclear radiation level gauge based on normalized LMS filtering correction

In the measurement of liquid level in industrial site environment,noise interference can affect the measurement accuracy.In order to improve the measurement accuracy of liquid level in the viscous state,a nuclear radiation level measurement system based on the least mean square(LMS)filtering correction method is designed.The system uses STM32F103 as the control core and adopts HART bus HT1200M chip for remote signal transmission and reception.The adaptive LMS algorithm can be used for more accurate filtering,calculating iterative weight vector,updating weighted coefficient,effectively removing system measurement noise and improving the measurement accuracy.The results show that the nuclear radiation level gauge based on normalized LMS can correct the measurement system accuracy in adaptive rules,improve the measurement accuracy to meet the requirements of industrial field environment for liquid level measurement and enhance the industrial automation control degree.

The implementation of Automatic Adaptive Equalizer Based on LMS Algorithm

In this paper,the inter-symbol interference and eliminating method are introduced.After analyzing the principle of adaptive equalization,we designed an adaptive equalizer using the LMS algorithm,and constructed a simulation system using MATLAB.Then we analyzed the convergence speed and mean square error characteristic of the adaptive equalizer by changing the step length factor to test the performance of the algorithm.

A WSN Node Fault Diagnosis Model Based on BRB with Self-Adaptive Quality Factor

Wireless sensor networks (WSNs) operate in complex and harshenvironments;thus, node faults are inevitable. Therefore, fault diagnosis ofthe WSNs node is essential. Affected by the harsh working environment ofWSNs and wireless data transmission, the data collected by WSNs containnoisy data, leading to unreliable data among the data features extracted duringfault diagnosis. To reduce the influence of unreliable data features on faultdiagnosis accuracy, this paper proposes a belief rule base (BRB) with a selfadaptivequality factor (BRB-SAQF) fault diagnosis model. First, the datafeatures required for WSN node fault diagnosis are extracted. Second, thequality factors of input attributes are introduced and calculated. Third, themodel inference process with an attribute quality factor is designed. Fourth,the projection covariance matrix adaptation evolution strategy (P-CMA-ES)algorithm is used to optimize the model’s initial parameters. Finally, the effectivenessof the proposed model is verified by comparing the commonly usedfault diagnosis methods for WSN nodes with the BRB method consideringstatic attribute reliability (BRB-Sr). The experimental results show that BRBSAQFcan reduce the influence of unreliable data features. The self-adaptivequality factor calculation method is more reasonable and accurate than thestatic attribute reliability method.

Hetero-Epitaxy and Self-Adaptive Stressor Based on Freestanding Fin for the 10 nm Node and Beyond

A promising technology named epitaxy on nano-scale freestanding fin （ENFF） is firstly proposed for hetero- epitaxy. This technology can effectively release total strain energy and then can reduce the probability of gener- ating mismatch dislocations. Based on the calculation, dislocation defects can be eliminated completely when the thickness of the Si freestanding fin is less than 10nm for the epitaxial Ge layer. In addition, this proposed ENFF process can provide sufficient uniaxial stress for the epitaxy layer, which can be the major stressor for the SiGe or Ge channel fin field-effect transistor or nanowire at the 10nm node and beyond. According to the results of technology computer-aided design simulation, nanowires integrated with ENFF show excellent electrical perfor- mance for uniaxial stress and band offset. The ENFF process is compatible with the state of the art mainstream technology, which has a good potential for future applications.

互相关时延估计与基于LMS自适应时延估计对比

长期以来,时延估计一直是信号分析和处理的一个重要研究方向,又是目标定位跟踪系统的关键技术,在声纳、雷达、地震等领域被广泛应用。本文就基于自相关与基于LMS自适应的两种时延估计方法做了对比,发现前者简单易行,抗噪声干扰能力差;而后者虽复杂,但抗噪声干扰能力扰强。

基于LMS算法的数字基带预失真技术性能分析

预失真器(PD)的系数辨识是预失真系统的核心,最小均方(LMS)算法是自适应参数辨识的基本方法之一。在实际系统设计中,因射频信号采集造成的量化噪声的影响通常被忽略,短波发信系统非线性对数字通信误码率的影响研究不够充分。针对以上问题,理论分析并仿真LMS预失真器在维纳收敛条件下的抗量化噪声性能及误码率改善指标。结果表明:针对典型的短波功放,在预失真多项式阶数为7的条件下,LMS预失真能够使发射机互调指标改善44.7 dB;针对8PSK和16QAM调制的信噪比改善量分别达到1.6 dB和2.6 dB;非线性性能改善存在由射频信号采样量化噪声决定的MSE性能平板。

基于ELMS算法的电网谐波电流检测

在LMS自适应滤波方法的基础上,根据电网谐波快速检测的要求,导出实现最优权值快速计算的ELMS(Extrapolated LMS)算法公式,该算法在理论上能更有效地提高谐波检测的精度和检测实时性。理论研究和仿真表明,根据该ELMS算法设计的自适应滤波系统可实现对电网谐波的快速检测。

基于LMS Virtual.Lab的一种折叠机翼动力学仿真

对舰载机折叠机翼的折叠及展开运动过程进行动力学仿真研究,提出了一套基于LMS Virtual.Lab的折叠机翼动力学仿真建模方法,实现了机构的动力学仿真计算,得到了折叠机翼作动筒载荷、翼稍运动包络面、结构应力水平等动力学指标。

Synthesis and Design of 5G Duplexer Based on Optimization Method

A new optimization method is proposed to realize the synthesis of duplexers.The traditional optimization method takes all the variables of the duplexer into account,resulting in too many variables to be optimized when the order of the duplexer is too high,so it is not easy to fall into the local solution.In order to solve this problem,a new optimization strategy is proposed in this paper,that is,two-channel filters are optimized separately,which can reduce the number of optimization variables and greatly reduce the probability of results falling into local solutions.The optimization method combines the self-adaptive differential evolution algorithm(SADE)with the Levenberg-Marquardt(LM)algorithm to get a global solution more easily and accelerate the optimization speed.To verify its practical value,we design a 5 G duplexer based on the proposed method.The duplexer has a large external coupling,and how to achieve a feed structure with a large coupling bandwidth at the source is also discussed.The experimental results show that the proposed optimization method can realize the synthesis of higher-order duplexers compared with the traditional methods.

SL和LMS整合提升网络协作学习活动绩效的分析

虚拟协作活动的绩效直接影响网络协作学习的效果，而当前网络协作学习中的协作活动却是绩效不高的。文章通过secondlife和传统学习管理系统的整合，给学习者提供具有沉浸性和形象性的协作学习活动氛围，从而提升协作活动绩效，给网络协作学习注入新的力量。

基于B-LM圆环模型的NLOS信息约束单基站定位算法

针对当前室外蜂窝网多基站定位需要基站之间时间同步、数据同步的要求,以及NLOS环境造成的非服务区基站的信号可测性问题,该文提出基于B-LM圆环模型的NLOS信息约束单基站定位算法。首先根据散射体、目标和基站间的几何位置关系以及NLOS多路径信息构建定位方程,然后将定位方程转化为最小二乘优化问题,之后基于LM算法海森矩阵修正思想和拟牛顿2阶偏导构造思想提出B-LM算法,保证算法收敛于最优解,以得到目标位置。仿真结果表明,所提单基站定位算法能在宏蜂窝NLOS环境实现较高的定位精度。

Interference Management for DS-CDMA Systems through Closed-Loop Power Control, Base Station Assignment, and Beamforming

In this paper, we propose a smart step closed-loop power control (SSPC) algorithm and a base station assignment method based on minimizing the transmitter power (BSA-MTP) technique in a direct sequence-code division multiple access (DS-CDMA) receiver with frequency-selective Rayleigh fading. This receiver consists of three stages. In the first stage, with constrained least mean squared (CLMS) algorithm, the desired users’ signal in an arbitrary path is passed and the inter-path interference (IPI) is reduced in other paths in each RAKE finger. Also in this stage, the multiple access interference (MAI) from other users is reduced. Thus, the matched filter (MF) can use for more reduction of the IPI and MAI in each RAKE finger in the second stage. Also in the third stage, the output signals from the matched filters are combined according to the conventional maximal ratio combining (MRC) principle and then are fed into the decision circuit of the desired user. The simulation results indicate that the SSPC algorithm and the BSA-MTP technique can significantly reduce the network bit error rate (BER) compared to the other methods. Also, we observe that significant savings in total transmit power (TTP) are possible with our methods.

网络教学平台的扩展性研究

网络教学平台作为在线学习的基础性技术平台,支持着远程教学、多种在线学习活动和非正式学习的发展。在当前环境下,单一封闭的系统平台很难凭借自身力量满足教师和学习者多元化的教学设计和学习支持要求,缺乏可扩展性制约网络教学平台的发展。可扩展性是指软件系统扩展新功能的能力和容易程度。研究网络教学平台的扩展机制对于教育系统开发、学习工具应用、平台价值提升、个人学习环境建构等具有积极意义。对扩展性的分析可以从两个角度展开:面向集成的平台扩展与面向开放的平台扩展。面向集成的扩展方式主要使用Web组件、IMS LTI和模块开发等方式,面向开放的平台扩展主要通过开放API方式实现。不同扩展方式在教学支持、技术特征、标准规范等方面具有不同的特点。对网络教学平台的扩展性设计应在符合通用设计准则的基础上,从教学、功能、技术、环境等角度综合思考。

GIS局部放电源的时差定位方法研究

通过在GIS装置中置入放电模型的人工模拟缺陷方式,对GIS局部放电源时差定位技术中的时延计算方法进行了试验研究,包括信号波形特征点法与基于LMS的自适应时延计算法。实验室结果表明,基于LMS的自适应时延计算法能够提高时延计算的精度,是比较理想的时延计算法。

自适应滤波器在相关能量分析攻击中的应用

针对在能量分析攻击中有噪声的存在、攻击效率不高、攻击成功需要采集大量的能量曲线等问题,提出自适应滤波应用在能量分析攻击中滤除噪声来提高攻击效率。以在ATmega16上运行的AES-128算法的密钥为攻击目标,使用最小均方误差（LMS）自适应滤波器、变系数变步长S型（Sigmoid函数）LMS自适应滤波器及卡尔曼滤波器对原始数据进行滤波,使用相关能量分析（CPA）对原始数据及滤波后的数据进行攻击。实验结果表明,3种滤波后的数据与原始数据相比,正确密钥CPA的相关系数均有不同程度提高,正确密钥与错误密钥的区分程度增大,而且减少了完全猜出正确密钥所需要的能量曲线的条数。攻击成功所需要能量曲线的条数与原始数据相比,卡尔曼滤波后减少了21.5%,LMS自适应滤波后减少了56.3%,变系数S型LMS自适应滤波后减少了60.3%。自适应滤波方法能够明显提高CPA攻击的效率。

改进算法的峰均比抑制联合预失真技术

研究正交频分复用OFDM(orthogonal frequency division multiplexing)传输系统中高功率放大器HPA(High power amplifier)的自适应预失真方法。为了减少HPA非线性对OFDM传输系统的影响,通过改进的限幅法与自适应预失真技术相结合,降低OFDM信号的峰均比值,扩大HPA的线性化范围,从而补偿功放的非线性特性。提出一种基于变步长的最小均方LMS(Least meansquare)算法,并将其应用到基于记忆多项式模型的数字预失真系统中。仿真结果表明:结合峰均比抑制技术与自适应预失真技术,其性能优于单独使用自适应预失真技术,而且新的算法能有效地改善放大器的非线性特性,带外频谱抑制达到28dB。

基于FPGA和模型化设计的信号处理实验平台

介绍了一种基于FPGA和System Generator模型化设计方法的信号处理实验平台,该平台适用于信号处理相关课程的实验教学和创新活动,为高校创新人才培养提供了良好的途径。基于该实验平台完成了LMS自适应滤波器的设计和实现,并进行了性能分析。实验结果表明了仿真方法和实验平台的有效性。

基于RBAC的学院管理系统安全体系的设计与实现

以一个实际的学院管理系统为背景,阐述了基于RBAC模型的信息系统安全体系的设计与实现过程.首先介绍了RBAC的要点和优势;然后在学院管理系统的背景下对基本模型进行扩展,并且以模块化的思想方法抽象出学院管理中的权限树;最后介绍安全体系的两大要素——安全底层和安全权限子系统的设计与实现.

网络课程中学习管理系统的设计与制作

本文以《房地产营销管理》网络课程设计与制作实践为个案,探讨如何将学习管理系统(LMS)应用于网络课程设计与制作中,预示着网络课程开发的新动向。

基于LMS的网络化控制系统时延补偿控制

为了解决不确定性变化的互联网传输时延影响网络控制系统的动态性能,利用自适应最小均方(LMS)滤波算法对网络时延进行在线预估,基于优化网络控制系统结构设计了一种自适应时延补偿器。实验结果表明基于LMS算法时延预估方法对网络控制系统时变时延有较高的预测精度,根据预测的时延设计的时延补偿器很好的改善了远程控制系统的动态性能。