ON THE CONSTRUCTION OF ALGEBRAIC-GEOMETRIC CODES

1,Illtroduction'SincetheearlypapersbyG0ppa[1-31,algebralc-ge0metriccodeshavebeeninthespotlight0fcodingthe0reticresearchf0rab0uttwodecades.NumerousexcitingresultshavebeenachievedusingGoppa'sconstructi0noflinearcodesfromalgebralccurvesoverfinitefields,bothbyalgebraicge0metorsandcodingtheorists.Becauseofthedifficultyofthesubject,severalexplanatorypaPersandtextbookshaveappeared,seeforinstance[4-8].Inthispaperwepresentaquitedtherentpointofviewconcerningalgebraic-geometriccodes.Itiswellknownthataq…     

M—PN空间中的线性算子

本文讨论了Menger概率赋范线性空间(M—PN空间)上的连续线性算子空间、全连续线性算子空间、强有界线性算子空间的完备性。     

线性非时变正弦稳态电路的功率不能用迭加原理吗?

本文提出三个定理与三个推论,证明了线性非时变正弦稳态电路的功率能用迭加原理来计算的充要条件。分解独立源为初相位零与初相位90°的两个独立源,运用迭加原理,推导出化复数的代数运算为标量的代数运算来计算纯电阻(或纯电抗)线性非时变正弦稳态电路的电流、电压与有功功率(或无功功率)的方法,简化了计算。最后提出了线性非时变正弦稳态电路(包括直流稳态电路)的功率不能用迭加原理来计算的充要条件。     

密码学中伪随机数的产生问题

随着社会步入开放式的网络时代 ,对广泛应用于信息安全的密码学的研究越来越引起有关专业人士的兴趣。目前的加密体制仍以公钥体系为主流 ,且最常见的密钥选取方法就是选取一个具有某种特征的随机数 ,因此随机数的好坏就直接影响到密钥的安全 ,从而也就影响到整个加密体系的安全。本文阐述了一个好的伪随机数序列的条件 ,着重介绍了如何利用线性反馈移位寄存器产生m_序列的方法     

An experimental method for measuring friction behaviors of linear rolling guides

Friction behaviors of linear rolling guides （LRGs） are determined by many factors and are crucial for precision positioning. It is difficult to create an expression to describe the friction behaviors exactly and completely. A new experimental method for measuring the friction behaviors of one LRG individually was developed, and linear motor direct drive technology is utilized in the experiment setup. The position signal is acquired by a grating, and the friction of the LRG is deduced by the product of the mass of the moving part and its acceleration. In the experiment, the LRG can move with the friction only, and the friction transition from normal rolling to pre- rolling stage was detected. The asperities＇ deformations were utilized to explain it. Hysteresis loops and internal loops were measured. The results indicate the non-local memory of the LRG, and the historical trajectory have an important impact on the friction behaviors of LRGs in the pre-rolling stage.     

船体高谐调振动固有频率的估算

本文提出三谐调至五谐调主船体垂向和水平方向振动的固有频率估算的几个新公 式．这些公式是以实船激振试验时获得的固有频率为基础，采用线性回归的方法推导 出来的。这些公式特别适用于船舶设计的初始阶段。它不仅可用于普通强度钢材料建 造的船舶．而且也适用于中部区域内的主要构件采用高强度钢材料建造的船舶．     

Allocating the weights in the linear opinion pool

A standard approach to the combination of probabilistic opinions involves taking a weighted linear average of the individuals distributions. This paper reviews some of the possible interpretations that have been proposed for these weights in the literature on expert use. Several paradigms for selecting weights are also considered. Special attention is devoted to the Bayesian mechanism used for updating expert weights in the face of new information. An asymptotic result is proved which highlights the importance of choosing the initial weights carefully.     

群和线性半群的准完备性

本文提出了群完备和准完备的充要条件。同时,还较详尽地讨论了线性半群中的完备性问题。定出其所有的准完备类(即极大封闭集)     

线性不确定系统约束条件下的控制稳定统一问题

本文讨论了线性不确定系统在控制能量（或控制幅值）受限下的能控性和稳定性的统一问题，证明了判定不确定系统完全能控并且渐近稳定的充分条件，又给出了控制能量（或控制幅值）受限下状态不能控同时也不稳定的一个判据．     

岭型压缩主成分估计及其性质

本文定义了一类新的降维估计，称之为岭型压缩主成分估计。证明了，当参数满足一定条件时，它比主成分估计，岭型主成分估计及最小二乘估计有较小的均方误差。