Improved Identification Schemes Based on Error-Correcting Codes

As it is often the case in public-key cryptography, the first practical identification schemes were based on hard problems from number theory (factoring, discrete logarithms). The security of the proposed scheme depends on an NP-complete problem from the theory of error correcting codes:the syndrome decoding problem which relies on the hardness of decoding a binary word of given weight and given syndrome. Starting from Stern’s scheme [18], we define a dual version which, unlike the other schemes based on the SD problem, uses a generator matrix of a random linear binary code. This allows, among other things, an improvement of the transmission rate with regards to the other schemes. Finally, by using techniques of computation in a finite field, we show how it is possible to considerably reduce: — the complexity of the computations done by the prover (which is usually a portable device with a limited computing power), — the size of the data stored by the latter. Received March 10, 1995; revised version December 1, 1995     

Reed-Muller Codes on Complete Intersections

By using results and techniques from commutative algebra such as the vanishing ideal of a set of points, its a-invariant, the Hilbert polynomial and series, as well as finite free resolutions and the canonical module, some results about Reed-Muller codes defined on a zero-dimensional complete intersection in the n-projective dimensional space are given. Several examples of this class of codes are presented in order to illustrate the ideas. Received: March 11, 1999; revised version: November 6, 2000     

遗传密码子的通用性与特殊性

遗传密码子的通用性与特殊性是生物多样性的重要分子基础。本文就目前研究较多的热点密码子在线粒体和原生动物纤毛虫中的特殊性进行总结,并对其形成理论机制进行探讨,阐明变异密码子在线粒体中是通用密码子在漫长进化过程中的遗物,但在纤毛虫中则并非单一地由某个时间或从某个种类开始,而是独立多次地在各物种内分别产生。     

The a-invariant of some Reed-Muller Codes

The a-invariant, the defining ideal and the dimension of Reed-Muller codes arising from some subsets of the projective n-space over a finite field are determined. In some cases the minimal distance of the code is given. Received: May 20, 1998; revised version: April 27, 1999     

基于二维活码的计量仪器设备管理系统的应用

针对目前计量仪器设备信息种类多、数据量大、设备检定及维护任务重、管理信息化水平较低等问题,结合质量计量监督检测部门所处具体环境,设计基于二维活码技术的计量仪器设备管理系统,本文分别从系统功能、组成、开发技术应用效果等方面进行论述,该系统能有效地提高了相关人员的工作效率,为各检测机构的设备管理工作提供了可借鉴模式。     

我国行政区划代码标准修订和应用迎接新挑战

全国行政区划代码标准是支持我国经济发展和社会发展的重要基础标准。标准的修订工作遇到了许多挑战，主要包括部门间协调统一、与地方标准协调统一以及开发区问题等。本文提出了应对挑战的操作原则和解决方案，为标准的后期审查和报批，以及其他信息分类编码等标准的修订及应用提供理论参考和经验借鉴。     

全国行政区划代码标准应用现状及管理服务模式探究

行政区划代码标准作为支持我国经济发展和社会发展的重要基础标准,已经被广泛应用于各个政府部门和企事业单位的信息化工作中。社会经济的快速发展造成行政区划的不断变更,这就要求行政区划标准也跟着快速更新。但经本文对标准应用现状的考察分析发现,其存在着包括标准修订周期过长、代码内容不统一、系统间无法共享、缺乏质量监管等一系列问题。为了解决这些问题,本文提出了标准统一和代码粒度管理模式,以及快速发布和分级服务模式相配套的新的标准管理服务模式,突出管理的系统化和服务的个性化。本模式亦适用于其他代码类标准的管理与服务。     

The Lie-Group Shooting Method for Solving Classical Blasius Flat-Plate Problem

In this paper, we propose a Lie-group shooting method to deal with the classical Blasius flat-plate problem and to find unknown initial conditions. The pivotal point is based on the erection of a one-step Lie group element$\mathbf G(T) and the formation of a generalized mid-point Lie group element$\mathbf G(r). Then, by imposing G(T) = G(r) we can derive some algebraic equations to recover the missing initial conditions. It is the first time that we can apply the Lie-group shooting method to solve the classical Blasius flat-plate problem. Numerical examples are worked out to persuade that the novel approach has better efficiency and accuracy with a fast convergence speed by searching a suitable r ∈(0, 1) with the minimum norm to fit the targets.     

The Lie-Group Shooting Method for Thermal Stress Evaluation Through an Internal Temperature Measurement

In the present work we study numerical computations of inverse thermal stress problems. The unknown boundary conditions of an elastically deformable heat conducting rod are not given a priori and are not allowed to measure directly, because the boundary may be not accessible to measure. However, an internal measurement of temperature is available. We treat this inverse problem by using a semi-discretization technique, of which the time domain is divided into many sub-intervals and the physical quantities are discretized at these node points of discrete times. Then the resulting ordinary differential equations in the discretized space are numerically integrated towards the spatial direction by the Lie-group shooting method to find unknown boundary conditions. The key point is based on one-step Lie group elements: G(r) = G(y⁰,y^l). We are able to search missing boundary conditions through a minimum discrepancy from the targets in terms of a weighting factor r ∈ (0,1). Several numerical examples were worked out to persuade that this novel approach has good efficiency and accuracy. Although the measured temperature is disturbed by large noise, the Lie group shooting method is stable to recover the boundary conditions very well.     

光电经纬仪跟踪目标运动参数的一种确定方法

获取跟踪目标的运动速度、加速度可以预测目标后续的空间位置,对经纬仪持续捕获目标和地面武器系统攻击参数的确定具有重要的现实意义.在分析经纬仪跟踪空中目标原理的基础上,应用最小二乘曲线拟合法,建立目标在X,Y,Z方向的实时运动曲线方程,进而得到目标3个方向的速度、加速度与时间的函数关系,运用矢量运算确定了目标的瞬时速度、加速度参数.仿真了两台光电经纬仪交汇跟踪目标的跃升机动飞行,验证了上述方法的正确性.     

多管相贯线切割运动轨迹与位姿控制方法研究

针对空间多管相贯线的切割问题,基于简化的坡口模型,提出了一种实用的切割运动轨迹与位姿控制方法。用参数化图形方式给出了相贯线的计算模型,建立了由三维模型数据到6轴联动切割运动代码的转换算法。通过现场实际切割,表明该方法可明显提高相贯线的切割效率。     

曲面离散跟踪求交算法的研究

跟踪求交是参数曲面求交常用的算法,而对于离散化的曲面也可以采用类似的方法。笔者提出的离散化跟踪求交是用离散方法求出交线上的某一个交点,然后根据两相交小三角面片的空间几何关系确定该交线段的方向。依次用跟踪法求出整条交线,这样就有效地避免了用离散法求交线不连贯的问题。     

成都尚都服饰广场空气调节方式分析

该项目地处湿度较大的成都，定位为西部高档的服饰批发兼零售商场，就该空调系统使用风机盘管加新风机组还是用全空气系统，从初投资、运行费用、空气的品质、维修维护的方便性分析，认为该项目采用组合式空调机组的全空气系统比较合理，供同行们参考。     

基于非对称双CCD交汇的信号弹高度测量方法

采用双面阵 CCD 非对称交汇测量技术, 建立了交汇测量的数学模型, 在相机焦距和工作视场角等参数未知的情况下, 通过对采集视频图像的处理, 实现信号弹发射高度的测量, 并给出发射高度不同时相应测量相机的布站方案, 分析了误差来源, 估算了系统误差精度. 本测试方案具有测量精度高、容易实现、不受测量环境和场地的限制、排除了人工读取误差等优点, 缺点是测量的设备成本相对较高. 本方案也可用于检测烟花表演效果、烟花高度、烟囱高度的测量以及高压线悬弧高度的测量.     

包装机械的概念设计方案评选方法的研究

为了避开概念设计方案的组合爆炸问题,提出了一种方案评选的新方法。该方法首先用有向图描述方案的组合情况,然后用层次分析法分析有向弧的权重,最后应用路径搜索法找出最佳方案。该方法应用到了零速接纸机的放卷轴的设计上,证明了该方法能有效地减少方案评选的工作量。     

A new two-code keying scheme for SAC-OCDMA systems enabling bipolar encoding

In this paper, we propose a new two-code keying scheme for enabling bipolar encoding in a high-rate spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) system. The mathematical formulations are derived for the signal-to-noise ratio and bit-error rate (BER) of SAC-OCDMA system based on the suggested scheme using multi-diagonal (MD) code. Performance analyses are assessed considering the effects of phase-induced intensity noise, as well as shot and thermal noises in photodetectors. The numerical results demonstrated that the proposed scheme exhibits an enhanced BER performance compared to the existing unipolar encoding with direct detection technique. Furthermore, the performance improvement afforded by this scheme is verified using simulation experiments.     

枕式包装机色标自动定位方法

目的受色标印刷偏差、张紧力失衡、机械振动等因素影响,很难保证色标定位的准确性,为了提高枕式包装机色标定位精度,提出一种色标自动定位方法,并基于PLC设计相应控制系统。方法通过分析包装机械运行规律,详细阐述色标补偿原理。利用色标、刀位检测信号判断横封和纵封是否同步,并计算偏差数值。以横封位置为基准,通过调整纵封电机的脉冲频率和脉冲个数进行定位补偿。同时基于PLC搭建枕式包装机的控制系统,并介绍控制系统的硬件结构和软件设计思想。最后进行实验研究。结果切点位置均在色标点上,可以实现色标定位。结论该控制系统和方法能够满足包装机械对定位精度的要求,提高了包装机械的包装精度、效率,降低了次品率。     

价值与重量相等的0／1背包问题的一种解法

基于穷举法的思想,提出一种三角矩阵法,来解决价值与重量相等的0／1背包问题．三角矩阵法把一部分直接穷举搜索不可行的情况变得可行,通过系统原型进行数据验证,表明三角矩阵法有效．     

求解变系数对流扩散反应方程的指数型高精度紧致差分方法

本文给出了一种数值求解变系数对流扩散反应方程的指数型高精度紧致差分方法.我们首先将模型方程变形,借助常系数对流扩散方程的指数型高精度紧致差分格式,采用残量修正法得到变系数对流扩散反应方程的指数型高精度紧致差分格式;并从理论上分析了当Pelect数很大时,本文格式达到四阶计算精度时网格步长的限制条件;离散得到的代数方程组可采用追赶法直接求解.数值实验结果与理论分析完全吻合,表明了本文格式对于边界层问题或大梯度变化的物理量求解问题具有的高精度和鲁棒性的优点.