ATM基本交换单元的研究与实现

文章提出并实现了一种共享缓存式ＡＴＭ基本交换单元的设计方案,该交换单元有６条输入输出线路,它由１０片大容量ＦＰＧＡ组成。通过简单的电路修改,用两片超大容量ＦＰＧＡ可以实现９×９或１８×１８共享缓存的ＡＴＭ基本交换单元。     

随机排序模型及求解方法

本文介绍了随机排序模型,并对求解随机排序的基本方法作一简要综述。     

运用综合手段研究铅锌硫化物精矿的氧化和鉴定其产物

南京关口每年从国外进口铅、锌精矿达几百万吨,随着我国国民经济的发展,作为重要有色金属来源的该矿种的进口量仍将逐年增加。硫化物精矿在运输和储存过程中都有可能发生氧化,由此导致金属品位的波动是常见现象,然而此前在这方面的报导甚少。为此,作者以铅锌硫化物精矿为例对其进行了模拟状态下的氧化实验并采用能谱、光学显微镜、化学物相分析、X射线衍射分析、扫描电镜等手段对氧化前及氧化后的样品进行了鉴定。结果表明,在模拟精矿储运条件下两种精矿的氧化皆甚为明显,铅精矿为1.5%,而锌精矿达到了14.5%,由此引起的品位变化是不可忽视的。鉴于有色金属硫化物精矿在储运过程中呈现了它们的易氧化性并对品位产生影响,所以有关这类矿产品的商贸过程中涉及取样、样品加工和保管、公证等问题,均应在科学实验基础上规范化。     

耕地模糊综合定级体系初探

本文探讨了耕地模糊综合定级法的基本原理、特点和数学模型以及技术路线 ,并运用此法对耕地进行模拟定级 ,最后就此法的实际应用进行客观评价 .     

A METHODOLOGY FOR REDUNDANCY ASSIGNMENT IN PRIORITY ENCODING TRANSMISSION (PET) OVER ATM NETWORKS

A novel approach called priority encoding transmission (PET) was recently proposed to guarantee delivery of the highest-priority data and/or the timely recovery of real-time data in the transmission of multimedia information over lossy networks. PET allows different segments of a message to be assigned priority levels, resulting in encoding information with different amounts of redundancy; the receiver is then able to recover the information in priority order, based only on the number of packets received per message. In this paper we propose a methodology to determine the fractions of the packets sent that are needed at the receiver to meet the quality of service (QoS) loss requirements specified by the user. It allows mapping of the required segment loss probabilities on the corresponding parameters of the PET system. As a relevant case study, the proposed methodology has been applied to the transmission of MPEG video signals over an ATM network using PET. The relative numerical results are presented and discussed. © 1997 by John Wiley & Sons, Ltd.     

利用分级HA实现基于移动卫星的网络移动通信

本文介绍了网络移动技术在卫星移动通信中的应用,构建了利用卫星移动通信网扩展地面IP网覆盖的实现模型,然后在此基础上利用分级HA概念提出了一种改进的优化路由方案,最后分析了该方案的特点及需要解决的关键技术问题.     

分级实验中限制性开放的探索与实践

分级物理实验中限制性开放能够提高学生科研素质,激发学生的学习热情,促进综合职业能力。我校采用了物理实验分级教学和分级实验中限制性开放等手段,取得了良好的效果。     

Sorting Using Complete Subintervals and the Maximum Number of Runs in a Randomly Evolving Sequence

We study the space requirements of a sorting algorithm where only items that at the end will be adjacent are kept together. This is equivalent to the following combinatorial problem: Consider a string of fixed length n that starts as a string of 0’s, and then evolves by changing each 0 to 1, with the n changes done in random order. What is the maximal number of runs of 1’s? We give asymptotic results for the distribution and mean. It turns out that, as in many problems involving a maximum, the maximum is asymptotically normal, with fluctuations of order n ^1/2, and to the first order well approximated by the number of runs at the instance when the expectation is maximized, in this case when half the elements have changed to 1; there is also a second order term of order n ^1/3. We also treat some variations, including priority queues and sock-sorting. The proofs use methods originally developed for random graphs.     

Travelling wave solutions to Stokes’ problem for a fourth grade fluid

A non-linear partial differential equation modelling the flow of a fourth-grade fluid is derived. Both analytical and numerical travelling wave solutions admitted by the model equation are obtained.     

Global Priority Estimation in Multiperson Decision Making

The analytic hierarchy process generalized to synthesizing local preferences across a complex hierarchy structure into global priorities in multiperson decision making is considered in various approaches. They include classic eigenvector synthesis and multiplicative method, and several other suggested techniques, such as three-dimensional eigenvectors, and simultaneous linear and nonlinear estimations by whole hierarchy structure in synthetic optimizing procedures. A numerical example from marketing research with many criteria, subcriteria, alternatives, and respondents is presented. The quality of approximation compared by different approaches shows that the best results are produced by the nonlinear synthetic priority techniques. The techniques described have been successfully used in dozens of real-world projects and are very helpful for practical managerial decision making in complex hierarchies. Dr. Stan Lipovetsky is Senior Research Director, GfK Custom Research North America, Marketing Science, Research Center for Excellence. The author thanks Professor T. Rapcsak and two reviewers for insightful suggestions that improved the paper.