基于SIMD结构的多标准LDPC译码器的VLSI实现

近年来,支持多标准的LDPC译码器已逐渐成为研究的热点.与传统译码器相比,所设计的LDPC译码器具有以下优点:1.实现了一个码率、码长可配置结构,进而可以支持多种标准;2.采用了一种改进型TPMP算法,使译码器的存储器容量大大减少,避免了因分块LDPC码的非规则性所造成的数据冲突问题;3.采用基于SIMD处理器的硬件结构,实现了硬件的高度规整性,易于芯片布局布线;4.设计了一个6级可配置流水线,可分时构造校验节点处理单元和变量节点处理单元,提高了硬件利用率和系统数据吞吐率.用这种架构实现了一个同时支持CMMB和DTMB两个标准的多标准LDPC译码器;芯片规模为75万门,时钟频率为220MHz,数据吞吐率为300Mbps.     

矿井主通风机自动监控系统的设计

为了保障主通风机安全、可靠、经济地运行,提出了一种基于S7-300 PLC的矿井主通风机自动监控系统的设计方案;给出了该系统的结构,详细介绍了该系统中PLC的硬件及软件结构、模拟量的检测实现及采用智能型PID调节器XMA5000对风机负压和流量进行自动调节的方法。实际应用表明,该系统能够实现通风机的就地、集中、远方3种控制方式,提高了主通风机的自动化程度和运行可靠性。     

选择重传ARQ结合自适应调制系统的跨层分析和设计

提出一种针对选择自动重传(SR-ARQ)技术结合自适应调制系统(AMS)的跨层分析和设计方法.该方法采用有限状态马尔可夫链(FSMC),同时对物理层和链路层进行建模,然后用更新报酬(renewal-reward)理论对系统的有效吞吐量进行精确分析,并根据分析结果设计系统中所使用的参数.计算机仿真结果验证了该跨层分析方法的精确性,并可以从中看出本方法对系统参数选取的指导意义.     

Multi‐Unit Bayesian Auction with Demand or Budget Constraints

We consider the problem of revenue maximization on multi‐unit auctions where items are distinguished by their relative values; any pair of items has the same ratio of values to all buyers. As is common in the study of revenue maximizing problems, we assume that buyers' valuations are drawn from public known distributions and they have additive valuations for multiple items. Our problem is well motivated by sponsored search auctions, which made money for Google and Yahoo! in practice. In this auction, each advertiser bids an amount b_i to compete for ad slots on a web page. The value of each ad slot corresponds to its click‐through‐rate, and each buyer has her own per‐click valuations, which is her private information. Obviously, a strategic bidder may bid an amount that is different with her true valuation to improve her utility. Our goal is to design truthful mechanisms avoiding this misreporting. We develop the optimal (with maximum revenue) truthful auction for a relaxed demand model (where each buyer i wants at most d_i items) and a sharp demand model (where buyer i wants exactly d_i items). We also find an auction that always guarantees at least half of the revenue of the optimal auction when the buyers are budget constrained. Moreover, all of the auctions we design can be computed efficiently, that is, in polynomial time.     

试析Web程序中常见字符串问题的处理

从PHP实现字符串的正确输出入手,分析了PHP中相关字符串处理函数在Web程序开发中发挥的重要作用。     

计算机辅助外科手术空间配准技术的研究

医学图像和实际手术空间的配准问题是计算机辅助外科手术技术的一个重要的研究热点,它能够帮助医生选择最佳手术路径和减小手术损伤,实现手术的方便快捷和微创,提高手术成功率。主要研究了一种基于ICP算法的计算机辅助外科手术中空间配准技术,通过获取实验模型的空间坐标信息,进行点集配准,找到最优旋转矩阵和最优平移向量。并通过仿真实验给出了模拟的配准结果,仿真试验结果表明,ICP算法配准精度高,适用于计算机辅助外科手术。     

Evolutionary level set method for structural topology optimization

This paper proposes an evolutionary accelerated computational level set algorithm for structure topology optimization. It integrates the merits of evolutionary structure optimization (ESO) and level set method (LSM). Traditional LSM algorithm is largely dependent on the initial guess topology. The proposed method combines the merits of ESO techniques with those of LSM algorithm, while allowing new holes to be automatically generated in low strain energy within the nodal neighboring region during optimization. The validity and robustness of the new algorithm are supported by some widely used benchmark examples in topology optimization. Numerical computations show that optimization convergence is accelerated effectively.     

综合业务和区分业务比较研究

为了在Internet上提供有服务质量等级和保证的服务,现在已经提出的在传输层上的实现方案包括综合业务（Integtated Services）和区分业务（Differentiated Services)。本文分析了两种方案的体系结构、工作原理和服务类型,比较了二者在设计思想、实现机制、QoS特性等方面的差异和优缺点,介绍了两种模型相互结合的扩展体系结构及最新研究进展。