Environmental databases for management decisions: Alaska

The Alaska Department of Environmental Conservation has completed a conceptual design for an environmental database to support the entire department in monitoring, tracking and reporting functions. SCS Engineers has performed an evaluation of the design. This paper presents the results of that evaluation. Special emphasis is placed on the problems of designing and implementing such a system, and proposed solutions to those problems. Particularly important are methodologies for allowing the data to be shared among multiple users within the department. This paper discusses several techniques designed to allow maximum utility of the system.     

Transparency and antialiasing algorithms implemented with thevirtual pixel maps technique

The benefits of the virtual pixel maps technique in the support of high-quality rendering operations are described. A dedicated frame buffer with a fixed number of bits per pixel is inappropriate for implementing high-quality rendering techniques within the framework of a graphics computer system. The virtual pixel maps feature is an elegant abstraction for solving problems that inherently require a large number of bits per pixel. A system implementation is presented to illustrate the types of hardware rendering algorithms that benefit from the concept of virtual pixel maps. Two specific algorithms, namely, transparency and antialiasing, are used as examples, but many other algorithms could easily be adapted to such an environment     

Java Native Interface idioms for C++ class hierarchies

The Java^TM Native Interface (JNI) provides a set of mechanisms for implementing Java methods in C or C++. JNI is useful for reusing C and C++ code repositories within Java frameworks. JNI is also useful for real‐time systems, where compiled C/C++ code executes performance‐critical tasks, while Java code executes system control and feature tasks. Available JNI literature concentrates on creating Java proxy classes that allow Java clients to interact with C++ classes. Current JNI literature does not discuss Java proxies for entire C++ inheritance hierarchies; that is the topic of this paper. Our experience in reusing C++ class hierarchies within a Java framework has uncovered a set of useful techniques for constructing Java proxy class hierarchies that mirror their C++ counterparts. This report gives both high level design guidelines and specific programming idioms for constructing Java class hierarchies that serve as proxies for C++ counterparts. We begin by discussing opportunities for reuse within a proxy class hierarchy, as well as problems caused by differences between the Java and C++ approaches to inheritance. The two most significant differences are due to C++ support for invocation of a member function based on the static type of its class, and C++ support for multiple implementation inheritance. Two example C++ class hierarchies provide the basis for a set of sections that present the design guidelines and that codify the programming idioms. This work could serve as the basis for an automatic generator of Java proxy class hierarchies. Copyright © 2000 John Wiley & Sons, Ltd.     

An incremental elastic-plastic Finite Element solver in a workstation cluster environment Part II. Performance of a first implementation

This work illustrates results obtained by implementing in a parallel computer environment the gl rate formulation of the theory of plasticity and its integration scheme as illustrated in the preceding Part I. The Preconditioned Conjugate Gradient is used as a tool for repeatedly solving linear systems of equations. Although the investigation about the performance of the workstation cluster as a parallel virtual computer is still far from being completed, it is already possible to conclude that, in such an environment, several techniques proposed for reducing the computer time required by the iterative solver are not applicable. One purpose of the work is therefore to give guidelines in terms of expected performances of the Conjugate Gradient method when applied to stiff problems, in which the condition number may shoot up to the billions. Even if the implemented computer code is not based on the most convenient rate formulation in terms of parallelizability, as shown in Part I of this work, the obtained results indicate anyway that, for some categories of structural problems, the development of a parallel, element-by-element computer code is a promising line of work.     

Understanding usability issues addressed by three user-system interface evaluation techniques

Three structured judgment evaluation techniques were applied to a system with a graphical direct manipulation style interface, to understand the types of usability problems they address. These evaluation techniques were cognitive walkthrough, heuristic evaluation, and the Smith and Mosier (1986) guidelines. The authors wanted to learn whether the techniques identify problems: across all stages of user activity, which noticeably affect users' performance with the system, and which are important to the usability of direct manipulation-style systems. Results showed that the cognitive walkthrough method identifies issues almost exclusively within the action specification stage, while guidelines covered more stages. The walkthrough was best, however, and the guidelines worst at predicting problems that cause users noticeable difficulty (as observed during a usability study). All the techniques could be improved in assessing semantic distance and addressing all stages on the evaluation side of the HCI activity cycle. To evaluate the directness of engagements, improved or new techniques are needed.     

Toward representing management-domain knowledge

Guidelines for the application of artificial intelligence to management-domain problems are proposed. A tutorial highlighting the strengths and weaknesses of several popular knowledge representation techniques is presented. Matching the strengths of these techniques with the requirements of different management decision-making domains provides a basis for the proposed guidelines. Management areas for which current approaches to knowledge representation provide little support are also discussed.     

When do aquatic systems models provide useful predictions,what is changing,and what is next?

This article considers how aquatic systems modelling has changed since 1995 and how it must change in future if we are to continue to advance. A distinction is made between mechanistic and statistical models, and the relative merits of each are considered. The question of “when do aquatic systems models provide accurate and useful predictions?” is addressed, implying some guidelines for model development. It is proposed that, in general, ecological models only provide management-relevant predictions of the behaviour of real systems when there are strong physical (as opposed to chemical or ecological) drivers. Developments over the past 15 years have included changes in technology, changes in the modelling community and changes in the context in which modelling is conducted: the implications of each are briefly discussed. Current trends include increased uptake of best practice guidelines, increasing integration of models, operationalisation, data assimilation, development of improved tools for skill assessment, and application of models to new management questions and in new social contexts. Deeper merging of statistical and mechanistic modelling approaches through such techniques as Bayesian Melding, Bayesian Hierarchical Modelling and surrogate modelling is identified as a key emerging area. Finally, it is suggested that there is a need to systematically identify areas in which our current models are inadequate. We do not yet know for which categories of problems well-implemented aquatic systems models can (or cannot) be expected to accurately predict observational data and system behaviour. This can be addressed through better modelling and publishing practices.     

Adaptive Medical Workflow Management for a Context-Dependent Home Healthcare Assistance Service

The provision of health-care services and home assistance to the elderly and chronic patients is a challenging application scenario for Web Services composition, which support the integration of distributed, heterogeneous services in complex workflows. However, in order to support the management of the typical routine activities carried out when dealing with a patient, several contextual conditions, such as his health conditions and the presence of specialized personnel at his home, must be taken into account. Thus, context-awareness must be added to the developed services.In this paper, we present the architecture of a framework integrating workflow management and context-aware action execution to support the personalized management of medical guidelines in home health-care assistance services. The framework is based on the integration of Web Service and Autonomous Agents techniques, which enhance the execution of medical guidelines, handled as abstract workflows, with a context-sensitive execution of actions.     

A model-based augmented PID algorithm

For complex control problems, advanced techniques, such as model-based predictive control may give better control performance than the common PID controller. However, the extra complexity and limited support of control software especially at the distributed control system (DCS) level, may prohibit the application of advanced algorithms. Also, implementing model based control often requires a higher level of programming than is readily available at the DCS level. This paper addresses this problem by providing a control algorithm utilizing multiple DCS PID blocks to implement a model-based predictive control strategy. The approach was tested on process simulations and the algorithm was able to provide control performance similar to that of generalized predictive control.     

“过程”新论

“过程”本是计算机界早期的话题.关于“过程”的研究热潮早已成为过去,很长时间已很少有人谈及“过程”.然而,工作流和业务过程管理系统（BPMS）的出现使“过程”再次成为研究的热点.业务过程管理系统被认为是继工作流技术之后实现业务过程的创建、集成、复用的下一代技术.它在过程的描述、实现方法上用Process把业务流中的控制流、数据流和参与者统一起来.Petri Net是一种很好的描述过程管理的模型,它能够较好地描述系统执行过程中的并行、竞争和同步等特性.本文论述了建立过程模型中遇到的一些新问题,并介绍了一种基于Petri Net扩展后形成的信牌驱动式业务过程模型,和用于解决业务管理中诸多问题的方法和相关研究工作.     

The object-oriented DFT program library S/PHI/nX

In order to simplify the development and implementation process of quantum mechanical algorithms, we developed a set of object-oriented C++ libraries which can exploit modern computer architectures. The libraries are characterized as follows: (i) State-of-the-art computer science techniques have been applied or developed in this work to provide language elements to express algebraic expressions efficiently on modern computer platforms. (ii) Quantum mechanical algorithms are crucial in the field of materials research. The new libraries support the Dirac notation to implement such algorithms in the native language of physicists. (iii) The libraries are completed by elements to express equations of motions efficiently which is required for implementing structural algorithms such as molecular dynamics. Based on these libraries we introduce the DFT program package S/PHI/nX.     

Constraint maintenance in engineering design system: An active object-oriented approach

This paper proposes a framework of engineering constraint maintenance using an active object-oriented database and solves a problem encountered when implementing the framework. The framework is proposed for the information-driven CIM system that integrates engineering constraints as well as its data. It resolves problems of the existing application-oriented constraint maintenance in which constraints are scattered in heterogeneous applications. It is possible due to the integrated management of constraints on a database using triggers, that is, on an “active” database. Existing active object-oriented databases, however, cannot properly support certain constraints that are specified on a set of classes. Those are the cases where the constraints must be maintained in the forward direction along a class composition hierarchy as well as in the backward direction. We call these kinds of problems “backward propagation problems” and investigate several approaches to resolve them using currently available techniques. Based on an approach which uses virtual classes, a new constructor, called CONSTRAINT^CCH is proposed to support the backward propagation. Advantages of the proposed framework and the constructor for the backward propagation are demonstrated on a design constraint management that supports a control panel design.     

Toward Exception-Handling Best Practices and Patterns

Agreeing on a reasonable exception-handling style for your application and following a consistent set of exception-handling practices is crucial to implementing software that's easy to work with, comprehend, evolve, and refactor. Demystifying exception-handling design requires writing about proven techniques, guidelines, and patterns.     

基于PC架构的高性能CAVE系统

CAVE是一种具有高度沉浸感的虚拟现实系统，并拥有广泛的应用潜力，但由于价格的因素，CAVE系统尚未能够推广到一般用户．介绍一种基于4台联网高性能PC机架构的CAVE系统，在性能上接近甚至超越以SGI工作站为基础的CAVE系统，并能大幅降低系统造价，使CAVE得到更进一步的推广．研究工作在本实验室的PCCAVE系统的基础上进行，解决了有关同步、真实立体等问题并增加跟踪设备的支持．     

Development of a guideline-based decision support system with explanation facilities for outpatient therapy

For effective guideline implementation it is recommended to develop and apply carefully designed implementation strategies and instruments. Computerized decision support systems (CDSSs) are such instruments as they can improve guideline adherence by providing advice at the point of care. To improve the implementation of the Dutch cardiac rehabilitation guidelines a CDSS, named CARDSS, was developed. CARDSS actively provides care professionals with patient-specific, guideline-based treatment recommendations at the onset of a patient's rehabilitation trajectory. To maximize the chances of acceptance, CARDSS also provides explanation facilities and other additional information management services, and takes the working procedures specific to multidisciplinary outpatient care into account. CARDSS is currently used in over 40 Dutch cardiac rehabilitation outpatient clinics. This paper describes the development of the CARDSS system. In particular, technical issues are discussed concerning the delivery of active decision support, and the provision of advice rationales to users while taking account of dynamic clinical contexts and changing guidelines.     

Contextual music information retrieval and recommendation: State of the art and challenges

Increasing amount of online music content has opened new opportunities for implementing new effective information access services–commonly known as music recommender systems–that support music navigation, discovery, sharing, and formation of user communities. In the recent years a new research area of contextual (or situational) music recommendation and retrieval has emerged. The basic idea is to retrieve and suggest music depending on the user’s actual situation, for instance emotional state, or any other contextual conditions that might influence the user’s perception of music. Despite the high potential of such idea, the development of real-world applications that retrieve or recommend music depending on the user’s context is still in its early stages. This survey illustrates various tools and techniques that can be used for addressing the research challenges posed by context-aware music retrieval and recommendation. This survey covers a broad range of topics, starting from classical music information retrieval (MIR) and recommender system (RS) techniques, and then focusing on context-aware music applications as well as the newer trends of affective and social computing applied to the music domain.     

Multimodal selection techniques for dense and occluded 3D virtual environments

Object selection is a primary interaction technique which must be supported by any interactive three-dimensional virtual reality application. Although numerous techniques exist, few have been designed to support the selection of objects in dense target environments, or the selection of objects which are occluded from the user's viewpoint. There is, thus, a limited understanding on how these important factors will affect selection performance. In this paper, we present a set of design guidelines and strategies to aid the development of selection techniques which can compensate for environment density and target visibility. Based on these guidelines, we present new forms of the ray casting and bubble cursor selection techniques, which are augmented with visual, audio, and haptic feedback, to support selection within dense and occluded 3D target environments. We perform a series of experiments to evaluate these new techniques, varying both the environment density and target visibility. The results provide an initial understanding of how these factors affect selection performance. Furthermore, the results showed that our new techniques adequately allowed users to select targets which were not visible from their initial viewpoint. The audio and haptic feedback did not provide significant improvements, and our analysis indicated that our introduced visual feedback played the most critical role in aiding the selection task.     

基于多协议标签交换的IP组播技术

多协议标签交换（MPLS）和组播技术的结合可以获得MPLS的高速率、QoS、流量工程、VPN和组播的带宽节省两方面的益处,MPLS和组播是两种互补的技术,这对于带QoS参数的实时的多媒体应用是必须和紧迫的。文章综述了MPLS组播技术在实现机制、组播树的构建等方面的基本原理和研究进展,分析了存在的问题和发展方向。     

Integrating AI planning techniques with workflow management system

There is a variety of applications that can benefit from the ability to find optimal or good solutions to a proposed problem, automatically. The artificial intelligent (AI) community has been actively involved in efficient problem-solving in complex domains such as military or spacecraft problems with successful results. In this paper, we describe the integration of AI planning techniques with an existing workflow management system. We show how these techniques can improve the overall system functionality and help automate the definition of business processes. The work is based on a short study carried out at BT research laboratories as part of a larger programme that aims to provide technologies for a new generation of business support systems.