The general problem solving algorithm and its implementation

By generalising problem solving techniques such as divide-and-conquer, dynamic programming, tree and graph searching, integer programming and branch-and-bound, a general problem solving algorithm is deduced. Various examples of the use of this algorithm are given and its implementation on both sequential and parallel machines, such as the cosmic cube, is discussed.     

Syntactic abstraction in scheme

Naive program transformations can have surprising effects due to the interaction between introduced identifier references and previously existing identifier bindings, or between introduced bindings and previously existing references. These interactions can result in inadvertent binding, or capturing, of identifiers. A further complication is that transformed programs may have little resemblance to original programs, making correlation of source and object code difficult. This article describes an efficient macro system that prevents inadvertent capturing while maintaining the correlation between source and object code. The macro system allows the programmer to define program transformations using an unrestricted, general-purpose language. Previous approaches to the capturing problem have been inadequate, overly restrictive, or inefficient, and the problem of source-object correlation has been largely unaddressed. The macro system is based on a new algorithm for implementing syntactic transformations and a new representation for syntactic expressions.This material is based on work supported by the National Science Foundation under grant number CCR-8803432.Robert Hieb died in an automobile accident in April 1992.     

An execution profiler for modular programs

In modular programs, groups of routines constitute conceptual abstractions. A method for providing execution profiles for such programs is presented. The central idea is that the execution time for a routine is charged to the routines that call it. The implementation of this method by a profiler called gprof is described. The techniques used to gather the necessary information about the timing and structure of the program are given, as is the processing used to propagate routine execution times along arcs of the call graph of the program. The method for displaying the profile to the user is discussed. Experience using the profiles for hand-tuning large programs is summarized. Additional uses for the profiles are suggested.     

Branching bisimulation for probabilistic systems: Characteristics and decidability

We address the concept of abstraction in the setting of probabilistic reactive systems, and study its formal underpinnings for the strictly alternating model of Hansson. In particular, we define the notion of branching bisimilarity and study its properties by studying two other equivalence relations, viz. coloured trace equivalence and branching bisimilarity using maximal probabilities. We show that both alternatives coincide with branching bisimilarity. The alternative characterisations have their own merits and focus on different aspects of branching bisimilarity. Coloured trace equivalence can be understood without knowledge of probability theory and is independent of the notion of a scheduler. Branching bisimilarity, rephrased in terms of maximal probabilities gives rise to an algorithm of polynomial complexity for deciding the equivalence. Together they give a better understanding of branching bisimilarity. Furthermore, we show that the notions of branching bisimilarity in the alternating model of Hansson and in the non-alternating model of Segala differ: branching bisimilarity in the latter setting turns out to discriminate between systems that are intuitively branching bisimilar.     

模型检测新技术研究

1 引言软件是否可信赖已成为一个国家的经济、国防等系统能否正常运转的关键因素之一,尤其在一些诸如核反应堆控制、航空航天以及铁路调度等安全悠关(safety-critical)领域更是如此。这类系统要求绝对安全可靠,不容半点疏漏,否则将导致灾难性后果。如1996年6月4日,欧洲航天局阿丽亚娜(Ariane)501火箭因为其控制软件的规范和设计错误而导致发射37秒后爆炸。类似的报道屡见不鲜,如何确保这些系统的可靠性成为计算机科学与控制论领域共同关注的一个焦点问题。     

On the representation of automation using a work domain analysis

Work domain analysis (WDA) has been applied extensively within cognitive engineering as an analytic framework for the evaluation of complex sociotechnical systems in support of design. However, the WDAs described in the literature have not explored the representation of automated system components, despite the documented problems associated with operator-automation interaction and the requirements for operator support in complex automated systems. The current research examines the application of WDA to model an example automated system – a camera – by representing the camera along with its automated components as separate systems using the abstraction hierarchy (AH). Additionally, we contrasted this modelling approach with the more typical approach of modelling automation within a cognitive work analysis (CWA) by performing a control task analysis using the decision ladder. The results of these analyses suggest that, similar to non-automated systems, considering a separate representation of an automated system within the WDA may provide useful system design guidance in terms of user support and information requirements. The comparison of the AH and the decision ladder (DL) models indicates that the models provide different information about the requirements and support different user needs: the AH provides information about specific subsystems and components of the automation that are used for control and how they support functions and purposes of the automation while the DL shows how the control tasks are achieved interleaving automated actions with those of the user. The information obtained from modelling automation with the AH is different from what would normally be obtained by performing only a control task analysis, yet is necessary for operator support.     

中国南通珠算博物馆

本文通过解读中国南通珠算博物馆中蕴含的如传统黑白水墨画的意境之美,表达了建筑师立足本土文化,突出地域特色,对传统建筑文化发掘、提炼,用抽象的方法加以表现的设计理念。     

Peak Demands from Spray Irrigation

Although irrigation accounts for less than 2% of water use in the UK, direct abstraction for spray irrigation can be a significant user in certain catchments in dry summers. Peak demand is expected to grow nationally by 1–2% per annum on average, but this growth varies locally. Water resource planners need to know the peak demands and how they are likely to grow within each catchment or aquifer, and the likely local annual variation and timing of demand. This paper discusses how recent developments in irrigation modelling combined with the application of a 'geographic information system'can produce such forecasts, taking into account spatial variation in soils, climate, cropping and irrigation practice.     

关于建筑形式的对话——一个围绕阿科米星建筑设计事务所最新实践的讨论

本文记录了王方戟与庄慎一次关于建筑形式的对话，讨论主要围绕阿科米星建筑设计事务所的最新实践展开，内容涉及形式的入手、技巧、抽象、逻辑、本体和时间六方面的问题。     

利用超临界CO_2流体萃取酒花浸膏的研究

阐述了利用超临界ＣＯ_２流体萃取酒花的浸膏原理、工艺流程及主要特点。