圆锥曲线切线的对称轴作法

给出了圆锥曲线切线的一组性质,然后借助于圆锥曲线的对称轴,给出了圆锥曲线切线的一种作法.     

一种空间参数有理圆弧样条

有文献表明可利用向量值连分式插值,在平面上构造一种GC1连续的参数有理圆弧样条,并且给出了保形性条件,但没有给出构造空间参数有理圆弧样条的算法。文章也利用向量值连分式,构造了空间的一段参数有理圆弧,并给出了其圆心及半径公式,同时给出了一种可调的空间参数有理圆弧样条,达到了GC1连续。     

问题83的纯几何证法

问题83刊登于贵刊2007年第2期,第3期中给出的问题解答中运用了余弦定理等,且运算量较大,第10期中杨秀长老师又给出了一种解析证法,本文将给出一种纯几何的简证,以飨读者．     

与双曲线渐近线有关的一组优美性质

本文给出了与双曲线的渐近线有关的一组性质,并给出了证明.     

具有最优代数免疫阶布尔函数的构造

给出了代数免疫阶,汉明重量,非线性度和相关免疫阶之间的关系,得出构造密码学综合性质较优的布尔函数的一种思想,给出构造方法,并给出了实例.     

基于教育城域网信息管理系统的设计与实现

本文介绍了教育城域网的结构、功能,给出了一种基于教育城域网环境下信息管理系统的设计和实现方法,同时给出了一种基于角色的安全访问控制策略。     

2022年全国高中数学联赛(四川预赛)试题及解析

给出2022年全国高中数学联赛(四川预赛)试题及其解析,部分试题给出一题多解,解答题给出了有别于参考答案的精彩解法.     

圆锥曲线的一个性质

有众多文献给出了圆锥曲线的一些美妙性质,本文再给出一条,现介绍如下．     

对《补充一类可积函数》一文中证法的改进

本文针对文 [1]给出的定理 ,给出了一种更为简便的证明方法     

柯西中值定理点滴

本文简述了柯西中值定理的物理意义,给出了定理的积分证明,最后从定理的一种错误证明中给出罗必达法则的另一证明.     

一类非线性偏微分方程的摄动解法

首先用行波变换将非线性偏微分方程转化为非线性常微分方程,然后采用摄动方法直接求解该非线性常微分方程,最后求得了非线性Klein-Gordon方程的二级近似解.这种方法也可进一步推广用于求其它非线性偏微分方程的近似解析解.     

Numerical approach for a system of second kind Volterra integral equations in magneto-electro-elastic dynamic problems

INTRODUCTION In scientific and engineering problems, Volterra integral equations are always encountered and have attracted much attention (Christopher and Baker, 1977; Delves and Mohamed, 1985; Brunner and van der Houwen, 1986; Kress, 1989; Oja and Saveljeva, 2002; Maleknejad and Shahrezaee, 2004; Maleknejad and Aghazadeh, 2005; Zerarka and Soukeur, 2005). Generally, exact solutions are very difficult to find and solutions have been obtained for only some few special cases (Yan and …     

Chebyshev-Legendre method for discretizing optimal control problems

In this paper, a numerical method for solving the optimal control (OC) problems is presented. The method is enlightened by the Chebyshev-Legendre (CL) method for solving the partial differential equations (PDEs). The Legen-dre expansions are used to approximate both the control and the state functions. The constraints are discretized over the Chebyshev-Gauss-Lobatto (CGL) collocation points. A Legendre technique is used to approximate the integral involved in the performance index. The OC problem is changed into an equivalent nonlinear programming problem which is directly solved. The fast Legendre transform is employed to reduce the computation time. Several further illustrative examples demonstrate the efficiency of the proposed method.     

含海底泉的含水层系统中水头波动的解析解

考察了含有海底泉的半承压含水层系统中,在潮汐效应与越流共同作用下地下水水头的波动.该系统由潜水含水层、承压含水层和介于其间的弱透水层构成.在文献[1]的基础上,综合考虑弱透水层的越流及海潮载荷效率,利用地下水动力学、复变函数及数学物理方程的基本原理和方法,推出了承压含水层水头波动的近似解析解.     

SOFC temperature evaluation based on an adaptive fuzzy controller

The operating temperature of a solid oxide fuel cell （SOFC） stack is a very important parameter to be controlled, which impacts the performance of the SOFC due to thermal cycling. In this paper, an adaptive fuzzy control method based on an affine nonlinear temperature model is developed to control the temperature of the SOFC within a specified range. Fuzzy logic systems are used to approximate nonlinear functions in the SOFC system and an adaptive technique is employed to construct the controller. Compared with the traditional fuzzy and proportion-integral-derivative （PID） control, the simulation results show that the designed adaptive fuzzy control method performed much better. So it is feasible to build an adaptive fuzzy controller for temperature control of the SOFC.     

A Monte Carlo Simulation Study to Assess The Appropriateness of Traditional and Newer Approaches to Test for Measurement Invariance

Several structural equation modeling (SEM) strategies were developed for assessing measurement invariance (MI) across groups relaxing the assumptions of strict MI to partial, approximate, and partial approximate MI. Nonetheless, applied researchers still do not know if and under what conditions these strategies might provide results that allow for valid comparisons across groups in large-scale comparative surveys. We perform a comprehensive Monte Carlo simulation study to assess the conditions under which various SEM methods are appropriate to estimate latent means and path coefficients and their differences across groups. We find that while SEM path coefficients are relatively robust to violations of full MI and can be rather effectively recovered, recovering latent means and their group rankings might be difficult. Our results suggest that, contrary to some previous recommendations, partial invariance may rather effectively recover both path coefficients and latent means even when the majority of items are noninvariant. Although it is more difficult to recover latent means using approximate and partial approximate MI methods, it is possible under specific conditions and using appropriate models. These models also have the advantage of providing accurate standard errors. Alignment is recommended for recovering latent means in cases where there are only a few noninvariant parameters across groups.     

现代汉语并列式固定语羡余现象的认知解释

现代汉语并列式固定语羡余现象大部分表现为前项和后项同义或者近义,组合为固定语后,前项和后项都与固定语的语义相同;极少的一部分其中的一项在组合后的固定语中不再表义,形成偏义固定语。它们的形成有着深刻的认知基础,即同义、近义并列式固定语羡余现象形成的主要动因是认知上的距离象似性,而偏义固定语羡余现象形成的主要动因是认知域中的凸显原则。     

关于抽象多元复合函数求导问题的探析

多元复合函数偏导数的计算是多元函数微分中的重点和难点。本文将从一元函数引入复合函数求导法则,在理解一元复合函数求导的基础上,介绍二元函数复合抽象函数求导,然后选取合适的例题,从具体的复合函数求导例题再过渡到抽象函数求导例题,循序渐进的过程,学生能够直观理解,最后给出了复合函数求导要注意的几点问题。     

第二类Fredholm积分方程的快速数值解法

对于具有弱奇性核函数的第二类Fredholm积分方程，将核函数所定义的区域分成大小不同的正方形子区域，利用分层插值多项式逼近核函数，由此得到近似矩阵B实现了积分方程的快速数值解法。在最后，对如何提高方案的数值稳定性作简要讨论并给出要讨论并给出数值结果。     

微小误差准则在科学实验中的重要地位

从实验设计、科学常数取值、误差的有效数字表示与近似原则三个方面分析了微小误差准则在科学实验中的应用和重要地位,得到微小误差准则在科学实验和实验教学中的一般应用规律,有效提高科学实验的精度.