Mathematical Modelling Of Wreck Events Originated By Dam Collapse

Based on Saint-Venant (shallow water) equations, in this paper the mathematical model of wreck events produced by dam collapse is constructed. A two-layer difference scheme with non-linear regularisation is used for the numerical solution of the aforementioned model. The convergence of this difference scheme in Eulerian variables with non-linear regularisation to the smooth solutions of one-dimensional Saint-Venant equations are considered for a Cauchy problem with periodic (in spatial variables) solutions. The proof of difference scheme convergence is conducted using the energetic method. The existence and uniqueness of the difference scheme solution is proved. That the difference scheme converges in mesh norm $L_2$ with speed $O\lpar h^2\rpar$ in the class of sufficiently smooth solutions of the difference scheme is also proved.     

关于二元等重码的最大码字数

本文利用Johnson Schemes理论研究了二元等重码及其最大码字数问题.在Delsarte的associate schemes理论中,Q-变换被引入以研究二元等重码的距离分布.首先,本文研究了等重码距离分布的Q-变换;然后,通过使用Q-变换的性质,我们研究了二元等重码的最大码字数问题并得到码字数的一个新的上界,该上界在形式上类似于纠错码理论中的Grey-Rankin界,并且在某些情况下优于已知的结果.     

Knowledge engineering concepts for decision support system design and implementation

The design of computer-based systems that simulate expert human consulting by drawing on large amounts of task-specific knowledge has been a major research activity of applied artificial intelligence over the last ten years. Building decision support systems that incorporate aspects of this research is a promising new field. The purpose of this paper is to discuss concepts of “knowledge engineering” that are most relevant in designing and building knowledge-based decision support systems.     

Analysis of playout strategies for voice transmission using packet switching techniques

Due to variations in network delay, a stream of voice packets with deterministic interarrival times to a data network may not have deterministic interdeparture times at the destination. Two playout schemes which are designed to remove such variations in delay are considered. Analytic results for the performance of these two schemes are obtained. Numerical examples showing the effect of coefficient of variation of interdeparture time on performance are presented.     

田湾核电厂址事故后果评价中天气取样方案的比较研究

本文基于田湾核电厂址1998年9月1日至1999年8月31日一整年的逐时气象数据、SF6实测扩散参数和评价区(40km×40km)各网格(2km×2km)人口分布等实测资料,对依据秦山、田湾核电厂址和惠安拟选核电厂址多年逐时气象数据统计分析后提出的五个天气取样候选方案,估算了某假想事故在评价区内造成的集体剂量,得到事故集体剂量余补累积概率分布函数(即CCFD曲线)。同时应用整年“逐时滑移”事故释放起始时刻方法计算了事故集体剂量的CCFD曲线,即“标准”CCFD曲线,并将五类天气取样候选方案获得的95%累积概率水平事故集体剂量值与由“标准”CCFD曲线得到的相应值作比较。结果表明,天气取样候选方案四最佳,此方案给出的95%累积概率水平事故集体剂量与由“标准”CCFD曲线得到的相应值的相对偏差仅为3%。     

APPLICATION OF INVERSE TRANSFORMATION TECHNIQUE TO 3-PHASE POLE-CHANGING WINDINGS

ABSTRACT

The inverse d-q transformation is used to develop pole-changing 3-phase induction motors from change-pole 2-phase ones. Transformation procedures, common features of the original 2-phase and derived 3-phase windings, basic differences between derived and conventional 3-phase windings together with their limitations are discussed in detail. Single winding change pole arrangements for 3-phase machines are derived from 2-phase ones. In addition, a mathematical model is presented to take satisfactorily into account the effects of unbalanced impedances and multi harmonic interactions. Tests conducted both in 2 and 3-phase operations on a 10/6 change-pole machine are reported. The nature of agreement between the computed and experimental results validates the transformation technique and also the mathematical model used in the process.     

Towards a logic programming methodology based on higher-order predicates

This paper outlines a logic programming methodology which applies standardized logic program recursion forms afforded by a system of general purpose recursion schemes. The recursion schemes are conceived of as quasi higher-order predicates which accept predicate arguments, thereby representing parameterized program modules. This use of higher-order predicates is analogous to higher-order functionals in functional programming. However, these quasi higher-order predicates are handled by a metalogic programming technique within ordinary logic programming. Some of the proposed recursion operators are actualizations of mathematical induction principles (e.g. structural induction as generalization of primitive recursion). Others are heuristic schemes for commonly occurring recursive program forms. The intention is to handle all recursions in logic programs through the given repertoire of higher-order predicates. We carry out a pragmatic feasibility study of the proposed recursion operators with respect to the corpus of common textbook logic programs. This pragmatic investigation is accompanied with an analysis of the theoretical expressivity. The main theoretical results concerning computability are

1. Primitive recursive functions can be re-expressed in logic programming by predicates defined solely by non-recursive clauses augmented with afold recursion predicate akin to the fold operators in functional programming.
2. General recursive functions can be re-expressed likewise sincefold allows re-expression of alinrec recursion predicate facilitating linear, unbounded recursion.

     

机械产品概念设计方案生成技术研究及软件系统开发

概念设计方案生成被认为是产品概念设计中最为关键的技术。它是决定产品最终质量、市场竞争力以及企业获利最为重要的因素。本文基于公理化设计 (AxiomaticDesign)理论 ,讨论了机械产品概念设计方案生成的关键技术和实现策略 ,并介绍了相应的软件系统开发     

用Magnus方法解无阻尼Landau-Lifshitz方程

§1.引言 在非平衡态磁学的研究中,Landau-Lifshitz(LL)方程对描述连续铁磁体自旋场发展过程起着十分重要的作用。在无阻尼情况下,它为一完全可积系统。很多物理学家研究了它的孤立子解的存在性,逆散射方法以及相互碰撞。关于解的存在性,Alouges和Soyear给出了整体弱解的存在性和不唯一性。最近几年来,以郭柏灵为代表的数学家给出了解的存在性