基于面向对象的可视化无线信道建模方法

移动无线信道特性的建模和仿真对于现代数字移动通信系统的研发具有重要意义.本文提出一种基于面向对象的可视化无线信道建模仿真方案,并对三种具有普适性的冲激响应信道模型进行了从模型转换、参数设计到图形建模等环节的模拟实验,建立起统一的、一体化的信道建模仿真实验框架,为移动无线信道的建模仿真分析和传播预测提供了一种可视化的解决方案.     

Estimating the Ozone Depletion Potential of Methyl Bromide

Ozone depletion potential (ODP) represents the cumulative ozone depletion induced by a particular halocarbon relative to a reference gas (usually trichlorofluoromethane, CFC-11). We focus on ODP estimation for methyl bromide. Previous attempts at its estimation have assumed that components of the ODP equation are lognormally distributed. By considering a wide range of modeling scenarios, we show that this restriction (which is based on computational convenience rather than experimental evidence) has obscured the true uncertainty in the ODP value. Moreover, when publishing point estimates for the ODP value, previous authors have given either mean or median values. We submit that a more appropriate choice for a point estimate is the mode since the distribution of ODP is skewed and since the mode is by definition, the most likely value. For each modeling scenario considered, modal values are given. In general, we find these ODP point estimates are considerably lower than those published elsewhere.     

基于Petri网的出口物流系统建模研究

出口物流系统是由离散业务组成的动态的系统,其业务流特征是以信息的传递和处理来推动系统的运行。本文在介绍Petri网定义、变迁规则的基础上建立其Petri网模型,提出业务流在Petri网中的运行方法以及利用Petri网分析其业务流属性的途径。     

Extreme value models with application to drought data

Summary The exact distributions of the productXY are derived whenX andY are independent random variables and come from the extreme value distribution of Type I, the extreme value distribution of Type II or the extreme value distribution of Type III. Of the, six possible combinations, only three yield closed-form expressions for the distribution ofXY. A detailed application of the results is provided to drought data from Nebraska. The author would like to thank the referees and the Associate Editor for carefully reading the paper and for their great help in improving the paper.     

关于模拟静电场的描绘的两种方法的比较

本文将模拟静电场的有关理论同实验方法，实验数据进行比较，指出在模拟静电场的描述的实验中，采用电压表进行测量时所存在的问题，提出了用电位差计代用，以补偿电压表的不足之处，从而改进该实验的具体方法。     

‘Wallbanking’, innovativeness and computer attitudes: 25–40-year-old ATM-users on the spot

Attitudes towards ‘wallbanking’ (making use of banking services through an Automated Teller Machine (ATM)) and self-reported frequency of wallbanking have been related to attitudes towards innovations and towards computers. The investigation also included the perception of advantages as well as disadvantages of wallbanking, factors that determine one's choice of a bank, man-machine problems related to the use of an ATM, and demographic factors. Using a sample of 201 respondents in the age range of 25 to 40 years, structural equation modeling revealed that wallbanking attitudes have a major influence on the frequency of using ATMs. The innovativeness attitude ‘New is wasteful’ also showed a clear negative link with the frequency of wallbanking. On the other hand, the relationship between computer attitudes and the frequency of using ATMs had to be rejected. Income and education proved to have an indirect link with the frequency of wallbanking, which refines other research findings. These results may reflect specific financial management characteristics of the age group under investigation.     

高师中国画造型基础课教学现状的反思

高师美术专业造型基础课教学所沿用的西画造型体系与中国画教学存在着严重的不适应,致使中国画教学难见成效。分析造型基础课与中国画教学之间存在的矛盾,找出问题的症结所在,是进一步调整和改革高师中国画基础课教学的前提。     

UNIX系统的性能评价

本文综述了一般计算机系统性能评价的基本方法,讨论了用基准检测模拟(BenchMark Modeling)的方法对操作系统进行评价。针对 UNIX 操作系统写出了不同的基准检测模拟程序,给出了它们在不同机器不同 UNIX 版本上的运行结果。     

蓝宝石微带色散特性研究

本文将谱域导纳法推广应用于各向异性介质基片微带,通过详细的理论分析,导出了各向异性等效传输线的特性导纳公式,并考虑了导带厚度的影响,建立了各向异性介质基片平面传输线传播常数色散特性的计算机程序。用本文推导的结果进行数值计算,在2-18GHz内求得的蓝宝石微带色散曲线与文献[1]的结果吻合得很好。此外,本方法直接、简明、且计算量小、适用于各类微波平面传输线的分析。因而,其具有较大的工程实用价值。     

Determination of Less-Than-Lifetime Exposures to Point Source Emissions

This paper presents a method of estimating long-term exposures to point source emissions. The method consists of a Monte Carlo exposure model (PSEM or Point Source Exposure Model) that combines data on population mobility and mortality with information on daily activity patterns. The approach behind the model can be applied to a wide variety of exposure scenarios. In this paper, PSEM is used to characterize the range and distribution of lifetime equivalent doses received by inhalation of air contaminated by the emissions of a point source. The output of the model provides quantitative information on the dose, age, and gender of highly exposed individuals. The model is then used in an example risk assessment. Finally, future uses of the model's approach are discussed.