Stancu型算子的逼近定理

引进Ｓｔａｎｃｕ型算子，并应用概率论方法，建立由连续模表达的逼近正定理，以及给出对有界变差函数的点态逼近度估计。     

点与线:结构视角初探

点与线是最简单的符号元素,也是人类抽象思维的最简约表现形式。本文考察了人类历史上认识点和线的方式和事件,阐述了点和线在揭示事物结构方面的作用,描述了人类以点与线作为符号工具重构对象并加以认识的思维活动。随着网络时代的到来,点和线将不再隐身于人类思维的后台,而将成为人们从网络这个时代标志的视角观察和了解各种系统的基本媒介。     

高压尖端放电气相色谱检测器

本文主要介绍研制新型GC放电检测器的结构、电路和部分实验结果。     

关于自相关函数计算法的探讨

本文系统地阐明了求自相关函数的几何法、代数法、分析法等方法。并从形与数两个不同的侧面及其结合上对自相关函数的算法进行了探讨,以期使自相关函数的计算得到较好的解决。     

关于一类有理递归序列的渐近性质

探讨了一个非线性差分方程的解的性态，指出该方程的一个系数与方程的解的全局渐进稳定性、单调解的存在性等的关系。     

光伏系统中一种改进MPPT算法的研究

针对传统扰动观察法存在功率振荡和误判的问题,提出了一种功率预测与自适应变步长相结合的扰动观察法。自适应变步长能够按照P-U特性曲线的斜率自动改变步长,进而解决传统扰动法跟踪速度与跟踪精度不能兼顾和稳定后功率波形振荡较大的问题。当光照强度发生剧烈变化时,功率预测法能够根据P-U输出特性曲线进行预测,进而达到消除误判的问题。在MATLAB/Simulink中搭建光伏系统MPPT仿真模型,并对改进扰动法和传统扰动法进行仿真对比,结果表明,改进的扰动法能够克服传统扰动法存在功率振荡和误判问题,可以使光伏系统快速、准确地实现最大功率点跟踪控制,并使之稳定运行在最大功率点处。     

Balance between facilitation and competition determines spatial patterns in a plant population

A considerable challenge in plant ecology is to understand how interactions,such as competition or facilitation,shape the spatial distribution of plants.The‘‘stress gradient hypothesis’’predicts that facilitation and competition will vary inversely across gradients of abiotic stress or consumer pressure.Surprisingly,few previous studies have explored how the balance between facilitation and competition affects spatial patterns along gradients of stress in a plant population based on field experiments.In order to investigate the effects of consumer pressure,facilitation,and competition on the spatial pattern of plant populations,we conducted a restoration succession series field experiment in the Inner Mongolian steppe in which sample sites of graded consumer pressure,specifically grazing stress,were established.We chose to examine the spatial patterns of Leymus chinensis,a dominant species in our experimental site.In order to test the‘‘stress gradient hypothesis,’’we applied the univariate O-ring statistic to analyze local neighborhood density at different spatial scales.We used the pair-correlation function to detect the characteristics of point patterns using complete spatial randomness,the Poisson cluster process,and the nested double-cluster process.We found that the local densities of L.chinensis were higher under high stress than lower stress environments.This demonstrated the‘‘stress gradient hypothesis’’in that facilitation and competition varied inversely across gradients of consumer pressure.However,we found nodifferences in the spatial patterns of L.chinensis based on complete spatial randomness when interactions shifted from facilitation to competition along gradients of consumer pressure.Furthermore,we detected the characteristics of point patterns using the Poisson cluster and nested doublecluster processes.The results showed the spatial patterns of L.chinensis to fit well with the nested double-cluster model under highly stressful conditions,while in lower stress environments they were best approximated by the Thomas process.Our results illustrate that a shift in interactions from facilitation to competition along gradients of consumer pressure can shape spatial patterns and that a combination of the Poisson cluster process and nested doublecluster process can detect spatial pattern characteristics which cannot be detected by complete spatial randomness.     

等势凝聚集

本文给出等势凝聚集的概念，得到了有别于导集的若干结果，由此产生了几个新概念，并讨论了它们的基本性质。     

W—空间中KFG不动点定理及其应用

文章首先给出在无线性结构的拓扑空间中的KKM定理。其次运用这个定理证明了在无线性结构的拓扑空间中的Kakutani-Fan-Glicksberg不动点定理。最后,作为应用在文章的第四节研究抽象变分不等式,隐变分不等式和拟变分不等式解的存在性问题,并且把Walras定理推广到了一般的拓扑空间中。     

COSMIC功能点方法在实践中应注意的问题

COSMIC功能点方法是由通用软件度量国际协会提出的新一代软件规模度量方法，已经纳入ISO国际标准。本文简要介绍了COSMIC功能点方法的基本理论和度量过程，在此基础上，针对实践中容易忽视的问题，通过案例说明的方式提出了解决方法，能够有效地减少度量中产生的误差。