基于Protel DXP的电路仿真设计

Protel DXP是集所有设计工具于一身的电子设计自动化(EDA)软件.文中运用其内嵌的仿真器叙述了分压式偏置电路放大器的仿真设计过程,设计过程简单、方便.在电子线路理论教学过程中引入电路设计仿真环节在不同情况下对电路进行实时分析,不仅可以提高学生的学习兴趣,而且能够在较短时间内加深学生对理论知识的理解;在工程设计过程中利用仿真工具对电路进行即时测试,可以缩短设计周期,提高设计效率.     

Matlab语言与线性电路的符号仿真

目前的电路仿真软件通常是在电路中所有元件值都是给定的情况下得到一些数值结果，而非解析结果。该文利用Matlab的符号运算功能编程，通过节点列表法，实现了任意线性电路的自动解析求解，为电路分析提供了一个有效的辅助工具。     

计算机高速并行通信的实现方案

利用CPLD芯片实现单片机与ISA总线接口之间的高速并行通信，给出系统的总体设计方法及程序框图。采用这种通信方式，在12MHz晶振的MCS51单片机控制的数据采集系统中，可以满足与PCI04 ISA总线接口实时通信的要求，通信速率达200khit／s。在开发工具MAX plusⅡ下，完成了整个设计的输入、编译和仿真，达到了预期效果。本设计方案能够推广应用到计算机的高速并行通信中。     

The Difference in Turbulent Diffusion between the Active and Passive Scalars in a Thermally Stably Stratified Medium

The difference in the turbulent diffusion between the active (heat) and passive (mass) scalars in a thermally stably stratified medium is investigated. The axisymmetric problem is treated on the formation of a turbulent circulation flow above a heated disk and on the turbulent diffusion of a passive scalar (impurity) from a continuous surface source in a stably stratified medium. The results indicate that the thermal stratification causes appreciable differences in the coefficients of turbulent transfer between the active (heat) and passive (mass) scalars. This means that the assumption of the identity of the coefficient of turbulent diffusion of heat and mass, employed in conventional models of turbulence, produces significant errors in estimating the heat and mass transfer in a thermally stably stratified medium.     

Ethical issues concerning expert systems' applications in education

This article traces the connection between expert systems used as consultants in medicine and their design for instructional purposes in education. It is suggested that there are important differences between these applications. Recognizing these differences leads to the view that the development of intelligent computer-assisted instructions (ICAI) should be guided by empirical research into social/psychological consequences and by ethical inquiries into the acceptability of those consequences. Three proposals are put forward: (1) that the pedagogical role of intelligent CAI be clarified, (2) that forms of intelligent CAI be developed that aim primarily at refining rather than replacing human judgements, and (3) that ICAI research and development projects contain components which address ethical and social/psychological components and which are equitably-funded, integral parts of the overall development effort.This work was supported in part by funds from the Foundation of the University of North Carolina at Charlotte and from the State of North Carolina. An earlier version of this paper was read at the Human Dimension in Artificial Intelligence Symposium held at the University of Kentucky (April 1988).     

Numerical solution for shape optimization of an impactor penetrating into a semi-infinite target

The shape of the impactor with the maximum depth of penetration (DOP) for a given impact velocity is found using a numerical procedure for solving a corresponding non-classical variational problem. It is shown that the optimum shape in a general case is close to a blunt cone. The variation of the optimal shape of the impactor and the dependence of the DOP vs. the initial (impact) velocity and friction coefficient is studied. The analysis is performed also for optimal conical impactors.     

Generation and selection of likely interpretations during plan recognition in task-oriented consultation systems

This paper presents a mechanism which infers a user's plans from his/her utterances by directing the inference process towards the more likely interpretations of a speaker's statements among many possible interpretations. Our mechanism uses Bayesian theory of probability to assess the likelihood of an interpretation, and it complements this assessment by taking into consideration two aspects of an interpretation: its coherence and its information content. The coherence of an interpretation is determined by the relationships between the different statements in the discourse. The information content of an interpretation is a measure of how well defined the interpretation is in terms of the actions to be performed on the basis of this interpretation. This measure is used to guide the inference process towards interpretations with higher information content. The information content of an interpretation depends on the specificity and the certainty of the inferences in it, where the certainty of an inference depends on the knowledge on which the inference is based. Our mechanism has been developed for use in task-oriented consultation systems. The particular domain that we have chosen for exploration is that of travel booking.