From the Lab to the Field

All of Steve Roth's achievements were the result of his fundamental belief in the unique value of people in the decision-making process. Nahum Gershon and Jake Kolojejchick discuss these achievements.     

Treeview控件构建VFP数据库字段树型目录

将ActiveX控件应用于Visual FoxPro中的一个实例。利用Comctl32.ocx文件中的TreeView控件,将VFP数据库字段构建出具有Windows文件夹分层列表展开的风格。使数据库字段选择既方便又美观。该程序可将任意VFP数据库中能被有效地分层显示的字段任意字段构建树型目录,也可稍加修改筛选不同类型的或条件的字段来构建树型目录。该实例具有一定的实用性,可根据需要将其嵌入自编的应用系统中,使自己的作品看起来更美观也更专业。     

Efficient Transitive Closure Reasoning in a Combined Class/Part/Containment Hierarchy

Class hierarchies form the backbone of many implemented knowledge representation and reasoning systems. They are used for inheritance, classification and transitive closure reasoning. Part hierarchies are also important in artificial intelligence. Other hierarchies, e.g. containment hierarchies, have received less attention in artificial intelligence. This paper presents an architecture and an implementation of a hierarchy reasoner that integrates a class hierarchy, a part hierarchy, and a containment hierarchy into one structure. In order to make an implemented reasoner useful, it needs to operate at least at speeds comparable to human reasoning. As real-world hierarchies are always large, special techniques need to be used to achieve this. We have developed a set of parallel algorithms and a data representation called maximally reduced tree cover for that purpose. The maximally reduced tree cover is an improvement of a materialized transitive closure representation which has appeared in the literature. Our experiments with a medical vocabulary show that transitive closure reasoning for combined class/part/containment hierarchies in near constant time is possible for a fixed hardware configuration. Received 10 January 2000 / Revised 25 November 2000 / Accepted in revised form 9 February 2001     

从类树形流程图到Z语言的形式化规格

在软件工程中,使用Z语言形式化规格可以大大提高软件开发质量,提高稳定性,降低开发成本,但要开发出高质量的形式化规格并通过验证,却需要损耗较多的时间和精力.为使软件开发人员能够较快地并且高质量地开发出基于Z语言的形式化规格,提出一种简明的类树形流程图,并以电信服务系统中的呼叫转移功能模块为例子,详细描述如何把类树形流程图应用到Z语言的形式化规格开发当中,以期为开发人员带来便利,节省开发时间,提高形式化规格的质量.     

Provisioning: From Cyber-sabotage Prevention to Collaboration Enabler Part 2

Business today is increasingly complex. Technology has advanced the network beyond the firewall to incorporate collaboration with partners, suppliers, contractors and even other enterprises. In fact, according to Gartner, by 2005 at least 70% of IT projects will extend beyond the enterprise, involving multiple business partners in some form of common functionality. Because of this, analysts are now urging businesses to think beyond traditional hierarchies. Instead, the call is for companies to view themselves as ecosystems in which each employee and customer become standard bearers of the corporate brand, or thinking more along dotted than straight lines.     

Isogeometric Analysis for Topology Optimization with a Phase Field Model

We consider a phase field model for the formulation and solution of topology optimization problems in the minimum compliance case. In this model, the optimal topology is obtained as the steady state of the phase transition described by the generalized Cahn?CHilliard equation which naturally embeds the volume constraint on the amount of material available for distribution in the design domain. We reformulate the model as a coupled system and we highlight the dependency of the optimal topologies on dimensionless parameters. We consider Isogeometric Analysis for the spatial approximation which facilitates encapsulating the exactness of the representation of the design domain in the topology optimization and is particularly suitable for the analysis of phase field problems. We demonstrate the validity of the approach and numerical approximation by solving two and three-dimensional topology optimization problems.     

Phase stability of the Hf-Nb system: From first-principles to CALPHAD

Hf-Nb is representative of a large number of alloy systems where the phase diagram is known but experimentally measured thermodynamic data is unavailable. This motivated us to investigate solid-state phase stability of this system employing ab-initio techniques based on electronic density functional theory (DFT). The total energy calculations are performed at the generalized gradient approximation level to account for non-locality of the exchange-correlation functional within DFT. The zero-temperature heat of formation of bcc-, hcp-and fcc-based ordered phases (virtual) and the finite temperature heat of mixing of bcc, hcp and fcc solid solutions are calculated. The latter properties are obtained by the cluster expansion technique coupled with Monte-Carlo simulations. In an effort to build multicomponent thermodynamic and kinetic databases containing Hf and Nb, we demonstrate a hybrid approach to integrate the ab-initio results with CALPHAD formalism to obtain thermodynamic data for the Hf-Nb system. The similarities and differences between previous CALPHAD assessment and our results are discussed.     

真前缀标记树——一种面向用户的子树选取策略表示方法

针对周期性任务处理中用户对操作数据的规则定义问题,提出了一种带有标记的真前缀树的表示方法,定义了树形数据集合上的选择/排斥规则。根据这种规则,用户制定的周期任务能自动地处理原有的和变化的数据。并给出真前缀标记树的一种GUI表现方式。     

From Ukkonen to McCreight and Weiner: A Unifying View of Linear-Time Suffix Tree Construction

We review the linear-time suffix tree constructions by Weiner, McCreight, and Ukkonen. We use the terminology of the most recent algorithm, Ukkonen's on-line construction, to explain its historic predecessors. This reveals relationships much closer than one would expect, since the three algorithms are based on rather different intuitive ideas. Moreover, it completely explains the differences between these algorithms in terms of simplicity, efficiency, and implementation complexity. Received February 12, 1995; revised January 28, 1996.     

Transformational design of real-time systems Part I: From requirements to program specifications

In the two parts of this article a transformational approach to the design of distributed real-time systems is presented. The starting point are global requirements formulated in a subset of Duration Calculus called implementables and the target are programs in an OCCAM dialect PL. In the first part we show how the level of program specifications represented by a language SL can be reached. SL combines regular expressions with ideas from action systems and with time conditions, and can express the distributed architecture of the implementation. While Duration Calculus is state-based, SL is event-based, and the switch between these two worlds is a prominent step in the transformation from implementables to SL. Both parts of the transformational calculus rely on the mixed term techniques by which syntax pieces of two languages are mixed in a semantically coherent manner. In the first part of the article mixed terms between implementables and SL and in the second part of the article mixed terms between SL and PL are used. The approach is illustrated by the example of a computer controlled gas burner. Received: 10 June 1996 / 29 December 1997     

From time series to linear system—Part II. Exact modelling

In the second part of this paper the problem of finding an exact model for a q-dimensional infinite time series is considered. First a mathematical vocabulary for discussing exact modelling is developed. It is then shown how the results of Part I guarantee the existence of a most powerful (AR) model for an observed time series. Two algorithms for obtaining such an (AR) model are subsequently derived. One of these algorithms gives a shortest lag input/output model. The problem of obtaining a minimal state space realization of the observed time series is also considered. In order to do that, realization theory based on the truncated behaviour is developed. As an extensive example, the classical situation with impulse response measurements is discussed.     

真前缀标记树——一种面向用户的子树选取策略表示方法

针对周期性任务处理中用户对操作数据的规则定义问题，提出了一种带有标记的真前缀树的表示方法，定义了树形数据集合上的选择/排斥规则。根据这种规则，用户制定的周期任务能自动地处理原有的和变化的数据。并给出真前缀标记树的一种GUI表现方式。     

Finite Element Approximation of a Three Dimensional Phase Field Model for Void Electromigration

We consider a finite element approximation of a phase field model for the evolution of voids by surface diffusion in an electrically conducting solid. The phase field equations are given by the nonlinear degenerate parabolic system

核磁共振测场仪的计量显示部分

测场仪利用核磁共振(NMR)原理,使用边缘振荡器法对磁场进行测量.计量显示部分以CPLD芯片EPM7128SLC84-6和单片机OM4368BN为核心部件,使用Verilog HDL和C语言设计频率计,测频范围为1MHz～100MHz.通过对共振点处边缘振荡器的振荡频率进行测量,由单片机根据拉莫进动公式计算出磁感应强度,送液晶显示器输出.设计中引入了自动量程转换,减少人工干预程度.     

Transformational design of real-time systems. Part II: From program specifications to programs

In the two parts of this article we present a transformational approach to the design of real-time systems. The overall starting point are requirements formulated in a subset of Duration Calculus called implementables and the target are programs in an OCCAM dialect PL. In the first part we have shown how the level of program specifications represented by a language SL can be reached. SL combines regular expressions with action systems and time conditions. In this part we show the transformation from SL to PL. It relies on the ‘Expansion strategy’ by which certain transformations can be applied in an almost automatic fashion. In many places transformations consist of algebraic reasoning by laws for operations on programs. Both parts of our transformational calculus rely on the mixed term techniques in which syntax pieces of two languages are mixed in a semantically coherent manner. In the first part of the article mixed terms between implementables and SL have been used, in the present part mixed terms between SL and PL are used. The approach is illustrated by the example of a computer controlled gas burner from part I again. Received 23 July 1996 / 13 February 1998     

Decoupled Energy Stable Schemes for a Phase Field Model of Three-Phase Incompressible Viscous Fluid Flow

We develop a numerical approximation for a hydrodynamic phase field model of three immiscible, incompressible viscous fluid phases. The model is derived from a generalized Onsager principle following an energetic variational formulation and is consisted of the momentum transport equation and coupled phase transport equations. It conserves the volume of each phase and warrants the total energy dissipation in time. Its numerical approximation is given by a set of easy-to-implement, semi-discrete, linear, decoupled elliptic equations at each time step, which can be solved efficiently using fast solvers. We prove that the scheme is energy stable. Mesh refinement tests and three numerical examples of three-phase viscous fluid flows in 3D are presented to benchmark the effectiveness of the model as well as the efficiency of the numerical scheme.     

Using SPIN to Analyse the Tree Identification Phase of the IEEE 1394 High-Performance Serial Bus (FireWire) Protocol

We describe how the tree identification phase of the IEEE 1394 high-performance serial bus (FireWire) protocol is modelled in Promela and verified using SPIN. The verification of arbitrary system configurations is discussed. Received July 2001/Accepted in revised form November 2002 Correspondence and offprint requests to: Alice Miller, Department of Computing Science, University of Glasgow, 17 Lilybank Gardens, Glasgow G12 8QQ, UK. Email: alice@dcs.gla.ac.uk     

From data topology to a modular classifier

This article describes an approach to designing a distributed and modular neural classifier. This approach introduces a new hierarchical clustering that enables one to determine reliable regions in the representation space by exploiting supervised information. A multilayer perceptron is then associated with each of these detected clusters and charged with recognizing elements of the associated cluster while rejecting all others. The obtained global classifier is comprised of a set of cooperating neural networks and completed by a K-nearest neighbor classifier charged with treating elements rejected by all the neural networks. Experimental results for the handwritten digit recognition problem and comparison with neural and statistical nonmodular classifiers are given.Received: 1 October 2002, Accepted: 21 November 2002, Published online: 6 June 2003     

From Circle to Ellipse: Footnotes to a Photographic Essay

In linguistics, ellipsis (from the Greek: élleipsis, “omission”) or elliptical construction refers to the omission from a clause of one or more words that would otherwise be required by the remaining elements. Photography encapsulates a wide range of experiential possibilities with the rhetoric of visualization and discursivity. The medium constantly reminds us of the basic geometric principles of perspective: perceived rather than measured, brought into consciousness through basic knowledge without need to name the phenomenon. It is the image that fills the gap, pronouncing elliptically what we feel, see and conclude, while the subject recounts the story.     

From orthogonal projections to a generalized quantum search

A quantum algorithm with certainty is introduced in order to find a marked pre-image of an element which is known to be in the image domain of an orthogonal projection operator. The analysis of our algorithm is made by using properties of the Moebius transformations acting on the complex projective line. This new algorithm closely resembles the quantum amplitude amplification algorithm, however it is proven that our algorithm is a proper generalization of the latter (with generalized phases), in such a way that the quantum search engine of the main operator of quantum amplification is included as a particular case. In order to show that there exist search problems that can be solved by our proposal but cannot be by applying the quantum amplitude amplification algorithm, we modify our algorithm as a cryptographic authentification protocol. This protocol results to be robust enough against attacks based on the quantum amplitude amplification algorithm. As a byproduct, we show a condition where it is impossible to find exactly a pre-image of an orthoghonal projection. This result generalizes the fact that, it is impossible to find a target state exactly by using quantum amplification on a three dimensional invariant subspace.