On the blow-up rate of large solutions for a porous media logistic equation on radial domain

In this paper we establish the exact blow-up rate of the large solutions of a porous media logistic equation. We consider the carrying capacity function with a general decay rate at the boundary instead of the usual cases when it can be approximated by a distant function. Obtaining the accurate blow-up rate allows us to establish the uniqueness result. Our result covers all previous results on the ball domain and can be further adapted in a more general domain.     

Fuzzy Model of Regional Economic Competitiveness in GIS Spatial Analysis: Case Study of Gansu, Western China

After more than 20 years of impressive development since the economic reforms in 1978, today western China is facing an increasing development gap between its regions, particularly between urban and rural areas. Using the fuzzy comprehensive evaluation model, this paper aims to demonstrate the evolution of the economic competitiveness levels base on two categories of geographical unity in the province of Gansu located in Northwest China between 2000 and 2004. The results of fuzzy modeling are integrated into GIS spatiotemporal analyses in order to identify the spatial variation of each significant change in terms of the regional economic development. Our research effectively illustrates that there is a particular spatial dynamic of the economic development from region to region. Although the cities have improved very well in their economic competitiveness, the rural areas and minority regions still have a lot of progress to be achieved.     

带干扰的Erlang(2)风险模型的不破产概率

本文讨论了带干扰的Erlang(2)风险模型,通过构造一个延迟更新过程,我们得到了不破产概率满足的积分-微分方程,进而得到了不破产概率的明确表达式．     

中高温工质在蒸发器中的换热模拟分析

本文采用分布参数的方法,建立了水源热泵中普遍采用的壳管式蒸发器稳态数学模型.通过中高温水源热泵试验台的实验数据同模拟计算结果的对比,验证了数学模型的准确性。应用此数学模型对中高温工质HTR01、HTR02及R134a在蒸发器典型制热运行工况,进行了模拟计算。得出了三种工质制冷剂侧换热系数沿管长的变化关系并对三种工质的换热性能进行了对比分析,为采用中高温工质的水源热泵换热器设计提供了参考依据.     

On existence of solutions for some hyperbolic-parabolic-type chemotaxis systems

In this paper, we discuss the local and global existence ofweak solutions for some hyperbolic–parabolic systems modellingchemotaxis.     

基于DEM的山地可照时间的空间分布

以山区高空间分辨率的DEM数据为主要数据源，在提取纬度、坡度、坡向等相应的地形要素栅格数据的基础上，利用GIS技术对山区可照时间的空间分布进行了模拟，实现了山区可照时间空间分布规律的可视化表达，分析了山区可照时间的空间分布特征，对于山区的农业、林业和生态环境等方面的研究具有重要意义．     

综合网管中基于模型驱动的元数据管理

提出了一种基于模型驱动的元数据管理方案．方案采用了基于模型的形式化描述方法，统一了专业网管子系统间的元数据模式；通过引入模型驱动技术，从元模型的抽象层次消除了不同专业网管子系统之间存在的“信息孤岛”；方案还对综合网管环境下的元数据理论和交换机制进行了研究，并给出了元数据的管理框架以及元数据交换的Java接口映射．     

多媒体教育资源库层次索引模型

依据多媒体教育资源各层次特征及其关系,通过定义资源媒体特征空间,构建了教育资源库层次索引模型,各层次特征间的映射规则将资源的高层语义特征映射到低层媒体特征,达到了扩充描述语义的目的,提高了查全率;结合学科本体,规范了资源标注内容和用户查询条件的描述,减少了人为因素对查询项和索引项匹配相似度计算的影响,提高了查准率.     

Two-sided bounds for the distribution of the deficit at ruin in the renewal risk model

We obtain lower and upper bounds for the severity of ruin in the renewal (Sparre Andersen) model of risk theory. We present two types of bounds: (i) bounds applicable generally; and (ii) exponential bounds for the case where the adjustment coefficient of the risk process exists. Many of these bounds are obtained using existing bounds and the integral equation for the severity of ruin.     

双对数模型对模型模拟误差的放缩问题探讨

对双对数模型lg Y=a0+a1lg X1+a2lg X2+…+anlg Xn与其对应的指数模型y=c0xa11xa22…xann的模拟相对误差的关系进行了探讨,指出双对数模型具有放大和缩小指数模型相对误差的特性.对二者的关系进行了理论推导和实例验证,并给出了二者的定量关系式.