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。     

国际经济格局趋势下的中国普通劳动者权益保护问题研究

多年来,中国被称为"世界工厂"。然而中国的主要出口商品都是一些中低端产品,制造业的技术含量普遍较低,其竞争力建立在廉价的劳动力成本之上,与此对应的是中国普通劳动者权益福利的丧失。中国人口基数巨大,劳动力市场供大于求。因此,提高普通劳动者权益不能只靠单纯的行政措施,而要顺应国际经济发展的大趋势,建立层次合理的产业结构。通过产业结构调整来增加就业岗位,吸纳劳动力,依靠市场的力量提高普通劳动者的福利。     

南极气雾立体栽培室风光互补供电系统研究

气雾立体栽培是一种新型农业无土栽培技术,该技术有望让极地科考队员吃上新鲜蔬菜,目前已在南极中山站展开初期调研试验。但"南极温室"需要日夜燃烧燃油加热来抵御极地严寒、能耗大、成本高。针对该问题,展开南极中山站气雾立体栽培室风光互补供电系统研究。依据南极中山站的气候特点研究风光互补供电可行性;分析负载用电特性,优化配置供电系统容量;应对中山站特殊的极昼、极夜现象和低温环境,提出供电系统能量管理和最大功率追踪控制策略;利用MATLAB对低温下风力发电系统、光伏系统最大功率追踪控制策略进行仿真。结果表明在中山站可用风光互补给气雾立体栽培室供电,所配置供电系统容量可靠,能量管理及最大功率追踪控制策略适用于中山站低温环境。     

邻近点CKQ法的强收敛性

引入了与邻近点算法（PPA）有关的新迭代序列,并利用CKQ法证明了这种迭代序列在一定的假设条件下强收敛.所得结论推广了有关文献中的相关结果.     

刘易斯拐点的争辩与求证

由于近几年民工荒的出现,学术界对"刘易斯拐点"是否已经来临进行了争辩。围绕"刘易斯拐点"三个要点,即农村是否存在剩余劳动力、工资是否显著提升和城市化进行求证后发现,中国经济"刘易斯拐点"并没有来临,中国目前仍处于人口红利时期。