Turbo-Coded Modulation of EVRC Speech Encoder with Unequal Error Protection for Fading Channels

The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Opti6n 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45dB at BER of 10^-5.     

A NEW SYSTEM DYNAMIC EXTREMUM SELF-SEARCHING METHOD BASED ON CORRELATION ANALYSIS

Inindustrialprocessesself searchingoptimumcontrolsystemshavebeenwidelyused ,becausetheydonotneedamathematicalmodel,whichhaveblockdiagram (seeFig .1) .Theprincipleistomakethecontrolsystemreachitsoptimumoperatingstatebycontinuousmeasuringandcontrolling.Thenec essaryconditionisthattheplantsmusthaveanex tremumcharacteristic[1 ] .Thekeyofself searchingoptimumcontrolishowtofindthesystemextremum pointautomati cally .Therearemainlytwokindsofself searchingmethods,whicharethecontinuoussearchingandthest…     

永磁电动机直接转矩控制中新型无传感器技术

剖析了两种典型转速直接估算方法,提出了一种新型的适用于永磁同步电动机直接转矩控制的无位置传感器技术.通过分别计算出定子磁链矢量角位移与转矩角,将后者从前者中减去得到转子磁链矢量的角位移进而得到转子速度信号,并采用改进积分器取代传统的积分器.该技术能有效地改善磁链原点漂移,提高直接转矩控制系统的磁链角位移与转速的求解精度.仿真及实验研究结果表明,采用这种无位置传感器技术的永磁同步电动机调速系统,具有良好的调速控制性能.     

DISCRETE VARIABLE STRUCTURE CONTROL OF LINEAR TIME-INVARIANT SYSTEMS WITH TIME DELAY

IntroductionIn recentyears,many methods have been pro-posed for the design of time- delay control sys-tems[1,2 ] and criteria for the stability of time- delaysystems have been developed by many re-searchers[3 ,4] .Time delay in the control systemscan be divided into two classes on the whole.Oneis in measurement of system variables and calcula-tion for required control force,including physicalproperties of equipmentused in the systems or sig-nal transmission.The other is in control for actua-to…     

Solving Electromagnetism Differential Equations Based on Random Walk

An approach of solving the finite difference equations with Monte Carlo method was presented. The accuracy of algorithm is guaranteed by the Central Limit Theorem. The computation of the value on each single node is independent of each other, which makes it easy to realize the algorithm in parallel processing and greatly improves the efficiency while dealing with local area computation. As long as different kinds of boundary conditions are statistics modeled ,wide applications can the be made where the finite difference method is of competence.     

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针对城市建设发展中道路交通阻塞问题，研究了两种类型的车辆路径与调度问题，给出了相应的求解框架，并构建了一个具有可变行驶时间的动态车辆路径与调度模型，涉及了车辆的固定费用、运营成本和早到或者延期的惩罚费用等多种费用。该问题是一个NP-hard问题，采用遗传算法确定最优解，并给出了车辆路径与调度方案的表示方式。最后设计了一个交通网络，通过动态交通仿真更新行驶时间，研究了多个不同时间段道路阻塞情况下算法的性能。结果显示比不考虑实时行驶时间信息的模型，该模型能够得到更低的总成本。     

基于频域法的结构疲劳寿命预测方法研究

以Didik方法的雨流循环计数应力范围概率密度函数为依据，考虑长寿命区的S-N曲线，利用不完全Γ函数建立了一种宽带随机载荷谱下结构疲劳寿命计算的解析解法，为用频域法计算结构在宽带随机载荷谱下疲劳寿命提供了一种快捷方法。     

基于微粒群本质特征的混沌微粒群优化算法

在总结对微粒群优化(PSO)算法本质的主要研究成果的基础上,提出了基于微粒群本质特征的混沌微粒群优化(CPSO)算法.该算法用混沌搜索方法代替随机数产生器在较好的区域搜索最优解.为了提高粒子群的多样性,用由粒子邻域内若干个个体最优位置依其适应值加权平均得到的中心位置代替标准PSO算法的全局历史最优位置.然后,根据粒子个体最优位置与上述中心位置间的距离自适应地调整混沌搜索区域半径.用几个经典测试函数的仿真结果及与其它几种PSO算法的比较结果验证了新算法的有效性.     

申嘉湖京杭古运河大桥设计浅议

针对申嘉湖高速公路京杭古运河大桥提出了预应力混凝土连续梁桥和斜拉桥两种不同的桥式方案。通过经济性、安全性、实用性、耐久性和施工等方面的比选,建议采用55m 80m 55m的变截面连续箱梁桥方案,并运用桥梁博士对主梁进行了施工阶段和使用阶段的内力计算和估索计算。验算结果表明,所选的预应力混凝土连续梁桥方案是合理的。     

混凝土桥梁预防性养护的评价体系

针对公路常用钢筋混凝土桥梁,对预防性养护评价技术进行了研究。考虑桥梁主梁、墩台基础及桥面等3个主要构件,提出以耐久性指标为目标的层次评价分析模型,采用层次分析理论（AHP）,根据对《公路桥涵养护规范》及许多工程的调查结果确定了指标层权重;并在综合评价过程中采用变权原理对模糊综合评价结果进行了处理,使结果更为均衡,建立了一套较完整的公路常用桥梁预防性养护评价体系,把不可测量的混凝土结构或构件耐久性逐层分解为可现场检测的定性或定量指标。实例表明本方法具有可操作性和逻辑性。