混沌扩频序列的优选算法及其系统性能研究

为了获得多址通信中优良的伪随机特性码组,提出了一种混沌序列的优选算法。通过对混沌系统迭代结果的截断和量化处理,根据扩频序列的理想特性和多址干扰指数,给出了优化混沌序列码组的具体步骤,并对传统的Gold序列和多种混沌序列的码组性能作了比较和分析。对DS/CDMA系统性能的仿真结果表明,优选混沌扩频序列的相关性能优于传统的伪随机扩频序列,有利于解决CDMA移动通信中的抗多址干扰及多用户检测等关键问题,从而使混沌扩频系统的抗干扰能力和抗破译能力得到增强。     

变步长LMS自适应极化递推估值算法

为了解决最小均方误差算法(least mean square,LMS)在干扰极化状态估值中存在的收敛速度和稳态误差之间的矛盾,应用变步长LMS算法进行干扰的极化状态递推估值。分析了传统定步长因子μ的选取和其对算法达到稳态时误差的影响;讨论了当干扰极化状态变化时算法的跟踪性能;并以雷达测角为例,进一步分析算法的实际应用可行性。最后给出了算法实现的原理方案。仿真结果和理论分析相一致,证明了该方法的有效性。     

超宽带系统中的迭代多用户检测算法

针对超宽带通信系统的多用户检测问题,将Turbo理论中的迭代思想应用于跳时超宽带多址通信系统的多用户检测中,提出了一种基于Turbo码的多用户检测与跳时超宽带多址系统相结合的联合应用方案———迭代多用户检测器,并推导出了一种基于软干扰消除和最小均方误差(MMSE)滤波的低复杂度迭代多用户检测算法,仿真结果证明,在室内超宽带信道条件下,使用该算法的这种接收结构的性能显著优于传统接收机,经过几次迭代后多址干扰被有效地抑制,系统性能明显提高。     

基于改进对数正态误差恒模算法的MIMO判决反馈

对数正态误差恒模算法误差曲线收敛速度快,但均方误差较大.针对这一问题,提出了改进的对数正态误差恒模算法,并将此算法应用于接序串行干扰消除MIMO判决反馈算法中.利用改进的对数正态误差恒模算法来得到前馈数据向量并将其合并到反馈数据向量中,然后按序将已检测并判决出的信号进行消除,避免了已判决出的信号对接收数据向量的干扰.在多散射物的无线通信环境下进行仿真,结果表明与迭代最小二乘按序判决反馈算法相比,所提算法检测性能提高,误码率显著下降.     

基于子空间的MMSE群盲多用户检测算法

针对CDMA上行链路系统中,基站已知小区内用户的扩频码而对小区外用户扩频码未知的情况,提出一种基于子空间方法的最小均方误差(minimum mean square error,MMSE)群盲多用户检测算法。该算法利用所有已知的扩频码有效消除了多址干扰,采用改进的紧缩近似投影子空间(projection approximation subspacetracking with deflation,PASTd)跟踪算法实现信号子空间的自适应跟踪,提高了收敛速度。仿真结果表明,所提算法收敛速度快,输出信干噪比和误码率性能优于PASTd盲多用户检测,逼近奇异值分解(singular value decom-position,SVD)群盲多用户检测,并保持了较低的计算复杂度。     

自适应变步长LMS滤波算法及分析

为了提高最小均方（LMS）自适应滤波算法的性能,通过建立步长因子与误差信号之间的非线性函数关系,提出一种自适应变步长LMS算法。该算法具有初始阶段和时变阶段步长自适应增大和稳态阶段步长很小的特点,消除了不相关噪声的影响,并且进一步克服了Sigmoid函数变步长LMS算法在自适应稳态阶段步长取值偏大的缺陷,计算机仿真结果与理论分析相一致,证实该算法优于传统算法。     

基于改进的双曲正切函数变步长LMS算法

为了改进现有的变步长最小均方误差(least mean square, LMS)算法在低信噪比时性能较差的缺陷,提出了一种基于改进的双曲正切函数的变步长LMS算法,从理论分析和仿真实验两方面讨论了引入参数对算法收敛性、跟踪性、稳定性的影响及算法的抗干扰性。理论分析和仿真实验表明该算法在高低信噪比时均具有较快的收敛速度和跟踪速度以及较小的稳态误差和稳态失调,并且在低信噪比时该算法的收敛性、跟踪性、稳态性均优于其他多种变步长算法。     

一种新的变步长LMS自适应滤波算法及性能分析

研究了自适应最小均方误差(least mean squares,LMS)滤波算法的步长选取问题。在详细分析现有变步长LMS算法的基础上,给出一种以双曲正切函数的改进形式为变步长的LMS算法。讨论了步长参数的选取原则及其对算法收敛性、抗干扰性和稳态误差的影响。该算法不但具有较快的收敛速度和跟踪速度,而且能获得更小的稳态失调。理论分析和仿真结果表明,该算法具有更好的稳态性能。     

噪声鲁棒变步长LMS算法及其在OFDM水声信道均衡中的应用

针对最小均方(least mean square, LMS)算法在低信噪比(signal to noise ratio, SNR)条件下性能较差的问题,提出一种噪声鲁棒变步长LMS(noise robust variable step-size LMS, NRVSLMS)算法。该算法通过结合改进的双sigmoid函数和误差信号自相关函数,在迭代过程中动态调整步长的大小,解决了传统LMS算法中收敛速度、跟踪性能和稳态性能互相矛盾的问题。理论分析和仿真结果表明,与其他变步长算法相比, NRVSLMS算法抗噪声能力强,具有良好的跟踪速度和稳态性能。将该算法应用于正交频分复用(orthogonal frequency division multiplexing, OFDM)水声信道均衡中,与现有LMS类自适应均衡方法相比,基于NRVSLMS算法的信道均衡方法能够显著降低系统误码率(bit error rate, BER)和均方误差(mean square error, MSE)。     

基于洛伦兹函数的变步长凸组合最小均方算法

为进一步减小收敛速率与稳态误差之间的矛盾,改善自适应滤波算法,利用改进的Lorentzian函数提出了一种新的变步长凸组合最小均方(new variable step-size convex combination of least mean square,NVS-CLMS)算法,该算法既有效提高了收敛速率又具备很好的抗干扰能力。同时,为了克服CLMS算法停滞等待的弊端,采用了瞬时转移结构;另外,在参数的迭代公式中使用sign函数进行优化以降低运算量。仿真结果证明该算法与CLMS、VS-CLMS相比,在不同的仿真环境中均能表现出良好的均方特性和跟踪特性。     

The 12th International Conference on Service Systems and Service Management ICSSSM'15

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Enterprise resource planning implementation decision & optimization models

To study the uncertain optimization problems on implementation schedule, time-cost trade-off and quality in enterprise resource planning (ERP) implementation, combined with program evaluation and review technique (PERT), some optimization models are proposed, which include the implementation schedule model, the timecost trade-off model, the quality model, and the implementation time-cost-quality synthetic optimization model. A PERT-embedded genetic algorithm (GA) based on stochastic simulation technique is introduced to the optimization models solution. Finally, an example is presented to show that the models and algorithm are reasonable and effective, which can offer a reliable quantitative decision method for ERP implementation.     

A calculus for services innovation

Innovation in the services area - especially in the electronic services （e-services） domain - can be systematically developed by first considering the strategic drivers and foci, then the tactical principles and enablers, and finally the operational decision attributes, all of which constitute a process or calculus of services innovation. More specifically, there are four customer drivers （i.e., collaboration, customization, integration and adaptation）, three business foci （i.e., creation-focused, solution-focused and competition-focused）, six business principles （i.e., reconstruct market boundaries, focus on the big picture not numbers, reach beyond existing demand, get strategic sequence right, overcome organizational hurdles and build execution into strategy）, eight technical enablers （i.e., software algorithms, automation, telecommunication, collaboration, standardization, customization, organization, and globalization）, and six attributes of decision informatics （i.e., decision-driven, information-based, real-time, continuously-adaptive, customer-centric and computationally-intensive）. It should be noted that the four customer drivers are all directed at empowering the individual - that is, at recognizing that the individual can, respectively, contribute in a collaborative situation, receive customized or personalized attention, access an integrated system or process, and obtain adaptive real-time or just-in-time input. The developed process or calculus serves to identify the potential white spaces or blue oceans for innovation. In addition to expanding on current innovations in services and related experiences, white spaces are identified for possible future innovations; they include those that can mitigate the unforeseen consequences or abuses of earlier innovations, safeguard our rights to privacy, protect us from the always-on, interconnected world, provide us with an authoritative search engine, and generate a GDP metric that can adequately measure the growing knowledge economy,     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

正August 10-14,2015Beijing,China The International Congress on Industrial and Applied Mathematics(IClAM)is the premier international congress in the field ofapplied mathematics held every four years under the auspices ofthe International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists and entrepreneurs fiom around the world will gather in Beijing,China for the 8th IClAM to be held at     

论生物系统中的功能不守恒性

根据能量守恒定律，能量一次转换所做的总功应等于输入的总能量。但在生物系统中，能量的转换是多次的，其总功之和大于系统输入的总能量，此现象称之为功能不守恒性。能量转换效率越高，功能差别越大。能量通过细胞水平的多次转换，总功可提高至2倍左右。能量通过生态系统水平多次转换，总功可提高至1．4倍左右。通过系统内各子系统能流之和称为序能，反映了系统有序性大小，它取决于系统输入总能量和能量转换效率。根据序能原理，用GDP^2／9(GDP为国内生产总值，Q为能量总输入)反映人类社会功能和效率，要比单纯用GDP更客观。绿色GDP应同时考虑使GDP^2／Q增长最大和使自然生态系统的序能最大。人的经济行为和动物的行为对策也符合序能原理。     

Dealing with Human Relations in Chinese Systems Practice

This paper is about the Wuli, Shili, Renli (WSR) systems methodology. An important concept within this, Renli, has been developed from Confucian philosophy to clarify to Chinese researchers the necessity of dealing with human relations in systems practice. At present, the only formal means of operationalizing Renli that people are exploring in China is to import from the West methods for organizing debate. However, the concept of Renli suggests that more is needed than methods alone. In particular, facilitation skills are required. It is argued that the development of facilitation skills can be enhanced if researchers can gain both theoretical and practical knowledge of group dynamics, and engage in activities of self-reflection to look at, and alter, their own roles in these dynamics and the wider sociopolitical system. There are therefore three aspects to Renli: the use of systems methods for organizing debate, the acquisition of facilitation skills, and self-reflection geared toward the development of facilitation skills and enhanced critical awareness of the politics of intervention.     

云环境中邮件服务器面向传输的优化设计

随着云计算的发展,新的应用不断涌现,但电子邮件服务依然占有着重要的地位.邮件服务器是一种I/O密集的应用.在云计算时代,越来越多的用户邮件保存在服务器端,邮件在从客户端传输到服务器端之前,邮件或者邮件的部分内容在服务器端可能已经存在.基于这种现象,提出了一种方案,通过引入计算的代价来降低通信量,从而提高邮件服务器的处理能力.对电子邮件的格式和SMTP协议进行了扩充,引入了附件和正文分离传输的模式.在邮件传输时,客户端先计算附件的散列值,并作为正文的一部分传输到服务器端,服务器端再根据散列值来判断附件是否需要传输.     

金工工艺的优化设计

运用价值工程与运筹工程理论, 在金工工艺单项设计指标优化的基础上, 对其设计指标也进行了全面优化。     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

正August 10-14,2015Beijing,ChinaThe International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists