Search

Two papers published by protein engineer Homme Hellinga's lab at Duke University Medical Center in Durham, North Carolina, have been challenged. Last year, Hellinga retracted papers in Science (1) and [...]

Studying chaotic systems at all levels of physics education can highly motivate students to learn physics. In this paper two simple systems, the Duffing oscillator and compass needle motion, are presented, which were used in a high school and in a university setting for teaching the basic ideas of chaotic motion. Studying both systems can begin with their simple mechanical models, which connect the mathematical description to tangible reality for the students. To surmount the mathematical difficulties of the theoretical treatment of the models, freeware software, the Dynamics Solver (DS), was applied. It will be shown how DS can facilitate students' first steps toward chaotic systems both at college and high school levels. Downloadable materials in ZIP format, related to this paper, can be found in our web page (http://csodafizika.hu/ds_girepmptl). Key words: physics education, chaotic problems, Dynamics Solver, Duffing oscillator, nonlinear oscillators. L'etude des systemes chaotiques a tous les niveaux de la formation en physique peut s'averer tres motivante pour etudier la physique. Nous presentons ici deux systemes simples, l'oscillateur de Duffing et le mouvement de l'aiguille d'un compas, qui furent utilises dans les cadres pre-universitaire et universitaire pour enseigner les notions de base du mouvement chaotique. L'etude des deux systemes peut commencer avec des modeles mecaniques simples, qui connectent la description mathematique a une realite tangible pour les etudiants. Afin de surmonter les difficultes du traitement theorique des modeles, nous utilisons le logiciel libre Dynamic Solver (DS). Nous allons montrer comment DS peut faciliter les premiers pas des etudiants vers les systemes chaotiques aux niveaux pre-universitaire et universitaire. Le materiel tele-dechargeable en format ZIP et relie a cet article peut etre trouve sur notre page web (http://csodafizika.hu/ds_girepmptl). [Traduit par la Redaction] Mots-cles : enseignement de la physique, systemes chaotiques, Dynamic Solver, oscillateur de Duffing, oscillateurs non lineaires., 1. Introduction A dramatic decrease in the number of physics students has been experienced at universities in Hungary, therefore, university and high school teachers have begun to seek ways of [...]

This paper presents a weighted least squares (WLS) method for IIR digital filter design using a new stability constraint. Utilizing the reweighting technique, an iterative second-order cone programming (SOCP) method is employed to solve the design problem, such that either linear or second-order cone constraints can be further incorporated. In order to guarantee the stability of designed IIR digital filters, a new stability constraint with a prescribed pole radius is derived from the argument principle (AP) of complex analysis. As compared with other frequency-domain stability constraints, the AP-based stability constraint is both sufficient and necessary. Since the derived stability constraint cannot be directly incorporated in the iterative SOCP method, the similar reweighting technique is deployed to approximate the stability constraint in a quadratic form, which is then combined with the WLS iterative design process. Filter design examples are presented to demonstrate the effectiveness of the proposed iterative SOCP method. Index Terms--Argument principle (AP), infinite impulse response (IIR) digital filters, reweighting techniques, second-order cone programming (SOCP), weighted least squares (WLS) approximation.

Modern exploits have evolved considerably over the last decade, with many powerful mitigations introduced, each requiring additional bypasses. Code-reuse attacks have become a central part of efforts to overcome some of these mitigations. This paper provides a novel approach to aid exploit developers by proposing an instantiation of an interactive, full-featured tool to facilitate the automated discovery of JOP dispatcher and functional gadgets, allowing for JOP exploits to be more easily constructed. Additionally, the tool will provide exclusion criteria to discard impractical JOP gadgets, while at the same time performing significant classification of gadgets found based on the target register and the operations performed. This proposed tool may be beneficial to exploit developers, as some systems hardened against ROP may be susceptible to JOP. This tool will be of benefit to the educational community by providing a simple, straightforward way to allow students studying software exploitation to be able to utilize JOP in exploits. Without such a tool, likely the level of difficulty and time-consuming, tedious nature of the work required to manually discover the needed gadgets would make the prospect of performing JOP virtually infeasible for both students and most practitioners. This proposed tool, thus, will make an entire class of code-reuse attacks accessible. Keywords--Return-orientated Programming, Jump-oriented Programming, Code-reuse Attacks, ROP, JOP, Cyber Operations Education, I. INTRODUCTION Exploits harness software vulnerabilities that have been weaponized to enable the attacker to perform arbitrary actions that may be benign as well as malicious. Code-reuse attacks have become [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cl.2008.05.002 Byline: Hiu Ning (Angela) Chan (a), Andrew J. Gallagher (a), Appu S. Goundan (a), Yi Lin William Au Yeung (a), Aaron W. Keen (b), Ronald A. Olsson (a) Abstract: The JR concurrent programming language extends Java with additional concurrency mechanisms, which are built upon JR's operations and capabilities. JR operations generalize methods in how they can be invoked and serviced. JR capabilities act as reference to operations. Recent changes to the Java language and implementation, especially generics, necessitated corresponding changes to the JR language and implementation. This paper describes the new JR language features (known as JR2) of generic operations and generic capabilities. These new features posed some interesting implementation challenges. The paper describes our initial implementation (JR21) of generic operations and capabilities, which works in many, but not all, cases. It then describes the approach our improved implementation (JR24) uses to fully implement generic operations and capabilities. The paper also describes the benchmarks used to assess the compilation and execution time performances of JR21 and JR24. The JR24 implementation reduces compilation times, mainly due to reducing the number of files generated during JR program translation, without noticeably impacting execution times. Author Affiliation: (a) Department of Computer Science, University of California, Davis, CA 95616, USA (b) Computer Science Department, California Polytechnic State University, San Luis Obispo, CA 93407, USA Article History: Received 24 January 2008; Accepted 16 May 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.sysarc.2008.07.001 Byline: K. Bousias, L. Guang, C.R. Jesshope, M. Lankamp Keywords: Architecture; Evaluation; Implementation; Microgrid; Microthread; SVP Abstract: Future many-core processor systems require scalable solutions that conventional architectures currently do not provide. This paper presents a novel architecture that demonstrates the required scalability. It is based on a model of computation developed in the AETHER project to provide a safe and composable approach to concurrent programming. The model supports a dynamic approach to concurrency that enables self-adaptivity in any environment so the model is quite general. It is implemented here in the instruction set of a dynamically scheduled RISC processor and many such processors form a microgrid. Binary compatibility over arbitrary clusters of such processors and an inherent scalability in both area and performance with concurrency exploited make this a very promising development for the era of many-core chips. This paper introduces the model, the processor and chip architecture and its emulation on a range of computational kernels. It also estimates the area of the structures required to support this model in silicon. Author Affiliation: Informatics Institute, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands Article History: Received 21 January 2008; Revised 7 July 2008; Accepted 16 July 2008

The grid has been proposed as a promising service-oriented platform for increasingly complex cooperative computing. The platforms of service-oriented grids are often Web-based where participants collaborate to achieve a common goal by sharing scarce Web-Based Computational/ Computing Resources (WBCR). To share the WBCR effectively is a challenging problem in boundary-spanning grid environments, particularly when these resources are subject to both static and dynamic usage. To set up the certificate-based usage policy described in this paper, we first explore a workflow engine-driven SOA-based resource access control mechanism. Then, aiming at setting up a cooperative computing paradigm from the resource sharing perspective, an infrastructure derived from a specific project of SOAEDSCCE (SOA-BasedEngine-Driven Structured Cooperative Computing Environment) is proposed for promoting its cooperative computing in grid environment based on the control disciplines and the WBCR usage policy. The main contributions of this paper are twofold: 1) a workflow engine-driven SOA-based WBCR sharing mechanism is presented in accordance with to the certificate-based usage policy; and 2) a specific infrastructure of cooperative computing is put forward for the collaboration based on the WBCR sharing mechanism.

This paper describes a method for training neural networks to learn circular dependencies. Variables with circular structure (e.g., time of day, day of year, and Earth location) appear in many different contexts within geoscience and remote sensing. Some common representations of circular variables (e.g., time of day in hours) can introduce discontinuities or topological distortions in estimation problems. They do not necessarily prevent a neural network from learning a relationship with circular dependencies. However, using topologically appropriate representations of circular variables can reduce the complexity necessary for a neural network to accurately learn such a relationship despite possibly increasing the number of inputs thereby reducing training times. In this paper, neural networks are trained to learn fictitious geophysical functions of time of day, of geolocation, and of time of year. In all three examples, using topologically appropriate representations of time and geolocation instead of conventional representations as inputs significantly reduced rms errors. Neural networks are also trained to learn the variations of air temperature observations with time of day and day of year, and one-month averages of sea surface temperature with geolocation. The improvement achieved by using topologically appropriate representations was limited by a natural random behavior in the data. However, there is a small but significant improvement in estimating the sea surface temperatures. Using the topologically appropriate representations of circular data when training the neural networks could be important in global Earth science remote sensing contexts, where significant diurnal, seasonal, or geographical variations exist. The studies presented also suggest the development of a more general framework for training neural networks that considers the topology of variables. Index Terms--Circular data, neural networks, pattern recognition, signal representation, spherical data.

Grid protocols and technologies are being adopted in a wide variety of academic, government, and industrial environments, and a growing body of research-oriented literature in grid computing is being compiled. However, there is a need for educational material that is suitable for classroom use. This paper describes topics, exercises, and experiences of teaching grid computing at two different universities. Course material in grid computing can be grouped into several knowledge areas. The focus in this paper is on grid programming, i.e., developing grid-enabled services using the Globus toolkit. Assessment data shows that with preparatory material and hands-on exercises, undergraduate computer science students can master grid programming. Topics and exercises for security, network programming, Web services, and grid programming are described. Recommendations include using stand-alone containers on individual student computers and following a first grid programming exercise that builds confidence with at least one more elaborate grid programming exercise. Index Terms--Computer science education, Globus toolkit, grid computing, grid programming, high-performance computing, network programming, security, Web services.

Byline: Andrew Martin (1) Keywords: Information; Technology; Application; Project; Architecture; Design; Performance; Software engineering Abstract: The technical architecture of an IT application is a critical determinant of its successful development. Complementing the software engineering viewpoint, this paper adopts a broader perspective to the design of IT applications and subsequent project success. It reports on a recent empirical study of factors that influence the design of IT application architectures. It identifies five influencing factors that are significantly associated with variation in the time-budget performance of the subsequent development project. Further, it finds that the projects can be classified according to these five attributes into four types that exhibit clear performance differences. The paper infers recommendations for good practice in IT application architecture design, contributes a detailed instrument for research into the area, compares with findings from software engineering, and raises issues for further study. Author Affiliation: (1) Warwick Business School, University of Warwick, Coventry, CV4 7AL, UK Article History: Registration Date: 14/11/2005 Online Date: 07/02/2006

This paper proposes a non-homogeneous Poisson process model for N-version software considering the case of imperfect debugging. The concept of linear dependency has been considered here for correlated errors. In this paper, combinatorial mathematics is used to predict the reliability of a multiversion software.

The concept of object-oriented programming (OOP) has redefined the design and development of large-scale codes worldwide and is now the order of the day in the software industry. Although OOP offers enormous potential in the scientific software business, this innovative programming technique has yet to find a niche in the development of structural engineering software. The present paper is an attempt to highlight the superior programming capability offered by the OOP approach in computer-aided analysis and design of civil engineering structures. The paper presents a brief theoretical background on the important basic and advanced concepts of OOP within the context of structural engineering. The paper explains the relevant fundamentals of object-oriented modeling and design in structural engineering for the orientation of civil engineering professionals who are new to the concept of OOE The paper provides simple examples of object-oriented programs for elementary structural analysis to illustrate implementation of the OOP paradigm for computational structural analysis. User-code fragments with accompanying commentary are included to provide more detailed directions to structural engineers who wish to adopt the OOP paradigm. The paper also includes a brief review of the evolution that the computational programming paradigm has undergone over the past few decades to cope with the increasing complexity of software. A comparison of currently prevalent programming paradigms is presented to illustrate the relative advantages of OOP for large-scale software applications in structural engineering. CE Database subject headings: Object-oriented languages; Computer programming; Structural analysis; Computer analysis.

Current scheduling practices in precast plants are fairly basic and depend greatly on experience. This may lead to inefficient resource utilization, over-inventory, and/or missing delivery dates. Computer assisted scheduling may therefore be useful in producing better production schedules. This paper shows how constraint programming (CP) can be applied in production scheduling for precast plants. The paper describes a constrained precast scheduling model that incorporates the key constraints and objectives considered by production schedulers. A capacity-based backward-scheduling earliest due date rule and a CP approach are developed to solve the model. The CP approach is computationally efficient, even though it incorporates many problem-derived constraints. The efficiency of the CP approach lies in the fact that the representation (model) is separated from the algorithm (solver). Strategies to improve the performance of the CP approach are identified, and the CP approach is compared against commonly used heuristic rules on an example problem. CE Database keywords: Construction; Computer aided scheduling; Computer programming.

Abstract This paper reports on the development and application of a method for establishing environmental priorities. The paper begins by reviewing two common methods for identifying environmental priorities: state of [...]

Overlapping communication with computation is a well-known approach to improving performance. Previous research has focused on optimizations performed by the programmer. This paper presents a compiler algorithm that automatically determines the appropriate loop indices of a given nested loop and applies loop interchange and tiling in order to overlap communication with computation. The algorithm avoids generating redundant communication by providing a framework for combining information on data dependence, communication, and reuse. It also describes a method of generating messages to exchange data between processors for tiled loops on distributed memory machines. The algorithm has been implemented in our High Performance Fortran (HPF) compiler, and experimental results have shown its effectiveness on distributed memory machines, such as the RISC System/6000 Scalable POWERparallel System. This paper also discusses the architectural problems of efficient optimization.

Byline: Thomas F. Rutherford (1) Keywords: applied general equilibrium Abstract: This paper describes a programming environment for economic equilibrium analysis. The system introduces the Mathematical Programming System for General Equilibrium analysis (MPSGE, Rutherford 1987) within the Generalized Algebraic Modelling System (GAMS, Brooke, Kendrick and Meeraus (1988)). This arrangement exploits GAMS' set-oriented algebraic syntax for data manipulation and report writing. The system based on the tabular MPSGE input format provides a compact, non-algebraic representation of a model's nonlinear equations. This paper provides an overview of the modelling environment and three worked examples in tax policy analysis. Author Affiliation: (1) Department of Economics, University of Colorado at Boulder, Boulder, CO, 80309, U.S.A. E-mail Article History: Registration Date: 03/10/2004

Byline: Fu Chunqian, Wang Xingsong A novel force-shoes system for measuring the zero moment point (ZMP) of human walker is introduced in this paper, which could measure the plantar distributed normal forces and friction forces during human walking. The improved ZMP calculation method developed in this paper is easy for programming. In contrast with the previous ZMP measuring methods, there are many advantages of the proposed force-shoes system, for example, light and novel structured, low coupling, easy for programming, less affection on normal walking, suited for long-time and diverse terrains testing. Two experiments carried out on different terrains, one is on the plain and the other is on the slope, are presented in this paper and some of the results are shown and discussed.

Byline: Uri J. Schild, John Zeleznikow The three laws of robotics formulated by Isaac Asimov have attained widespread acceptance in Science Fiction literature. A recent film relates to one of the stories in Asimov's book. It deals with what seems to be a fundamental problem of discretionary interpretation of the laws by robots. The main object of this paper is to analyse the modelling of judicial discretion by a computer program (in the future perhaps a robot). Only the interpretational aspect of the film is of relevance to this paper. It does not relate to the actions of humans or robots in the film or the present and future feasibility of those actions.

Byline: Josef Hynek, Kamila Olsevicova The aim of our paper is to describe our experience acquired during the development and subsequent utilisation of our Prolog programming e-course. We will describe our journey from printed textbooks, via isolated web-based materials to the comprehensive and integrated e-course. We have changed not only the method of delivery, but also the content of our course to make it more interesting and attractive for our students. Our new course is based on utilisation of various games that allow us to demonstrate key aspects of logic programming; at the same time the subject as a whole is very appealing. Moreover, using suitable games even difficult topics can be explained rather easily and spontaneously, as we will illustrate in this paper using a chess game. Finally, we will review our existing experience with the e-course utilisation and we will discuss the problems concurrent with it as well.

Byline: Yoshiaki Nakamura This paper investigates the advantages and disadvantages of a government sponsored research project, taking the Real World Computing (RWC) Program as an example. After discussing the organisation, budget, and research themes, I evaluate the contribution of the RWC Program compared with the Fifth Generation Computer Systems (FGCS) Project. The major findings of this paper are as follows: 1 The contribution of the program has been substantial compared with that of the FGCS Project in terms of the number of paper citations in the first six years. 2 Through participation in the program, the resulting R&D has had a spillover effect on the other research within the company, seemingly resulting in an increase in the number of patents taken out by the participating companies. Though the contribution of the program may have been substantial in the first six years, if MITI will further improve the structure for promoting the program to activate collaborative R&D, the contribution will be much bigger than before.

Concurrent programs that embed specifications of synchronizations in the body of their component are difficult to extend and modify. Small changes in a concurrent program, particularly changes in the interactions among components, may require re-implementation of a large number of components. Even specifications of components cannot be reused easily. This paper presents a concurrent program composition mechanism in which both specification and implementation of computations and interactions are completely separated. Separation of specifications and implementations facilitates extensions and modifications of programs by allowing one to separately change the implementations of computations and interactions. It also supports their reusability. The paper also describes the design and implementation of a concurrent object-oriented programming language based on this model, including a compiler for the language, and reports on the execution behavior of programs written in the language. KEY WORDS: Software evolution; concurrent programming; object-oriented programming; inheritance; genericity.

This paper describes a new algorithm for obtaining rules automatically from training examples. The algorithm is applicable to examples involving both objects with discrete and continuous-valued attributes. The paper explains a new quantization procedure for continuous-valued attributes and shows how appropriate ranges of values of various attributes are obtained. The algorithm uses a decision-tree-based approach for obtaining rules, but unlike other tree-based algorithms such as ID3, it allows more than one attribute at a node which greatly improves its performance. The ability of the algorithm to obtain a measure of partial match further enhances its generalization characteristic. The algorithm produces the same rules irrespective of the order of presentation of training examples. The algorithm has been demonstrated on classification problems. The results have compared favorably with those obtained by existing inductive learning algorithms. Index Terms--Machine learning, pattern classification, rule induction, system identification.

The paper presents neural dynamic optimization (NDO) as a method of optimal feedback control for nonlinear multi-input-multi-output (MIMO) systems. The main feature of NDO is that it enables neural networks to approximate the optimal feedback solution whose existence dynamic programming (DP) justifies, thereby reducing the complexities of computation and storage problems of the classical methods such as DP. This paper mainly describes the theory of NDO, while the two other companion papers of this topic explain the background for the development of NDO and demonstrate the method with several applications including control of autonomous vehicles and of a robot arm, respectively. Index Terms--Dynamic programming, information time shift operator, learning operator, neural dynamic optimization, neural networks, nonlinear systems, optimal feedback control.

The paper presents neural dynamic optimization (NDO) as a method of optimal feedback control for nonlinear multi-input-multi-output (MIMO) systems. The main feature of NDO is that it enables neural networks to approximate the optimal feedback solution whose existence dynamic programming (DP) justifies, thereby reducing the complexities of computation and storage problems of the classical methods such as DP. This paper demonstrates NDO with several applications including control of autonomous vehicles and of a robot-arm, while the two other companion papers of this topic describes the background for the development of NDO and present the theory of the method, respectively. Index Terms--Autonomous vehicles, dynamic programming, information time shift operator, learning operator, neural dynamic optimization, neural networks, nonlinear systems, optimal feedback control, robots.

The paper presents neural dynamic optimization (NDO) as a method of optimal feedback control for nonlinear multi-input-multi-output (MIMO) systems. The main feature of NDO is that it enables neural networks to approximate the optimal feedback solution whose existence dynamic programming (DP) justifies, thereby reducing the complexities of computation and storage problems of the classical methods such as DP. This paper mainly describes the background and motivations for the development of NDO, while the two other subsequent papers of this topic present the theory of NDO and demonstrate the method with several applications including control of autonomous vehicles and of a robot arm, respectively. Index Terms--Dynamic programming (DP), information time shift operator, learning operator, neural dynamic optimization (NDO), neural networks, nonlinear systems, optimal feedback control.

1. INTRODUCTION Software development environments (SDEs) are used to develop and maintain a diverse collection of highly interrelated software objects [Boudier et al. 1988; Fernstrom et al. 1992; Kadia 1992; […], Emerging software development environments are characterized by heterogeneity: they are composed of diverse object stores, user interfaces, and tools. This paper presents an approach for providing hypermedia services in this heterogeneous setting. Central notions of the approach include the following: anchors are established with respect to interactive views of objects, rather than the objects themselves; composable, n-ary links can be established between anchors on different views of objects which may be stored in distinct object bases; viewers may be implemented in different programming languages; and, hypermedia services are provided to multiple, concurrently active, viewers. The paper describes the approach, supporting architecture and lessons learned. Related work in the areas of supporting heterogeneity and hypermedia data modeling is discussed. The system has been employed in a variety of contexts including research, development, and education. Categories and Subject Descriptors: H.5.1 [Multimedia Information Systems]; D.2.2 [Software Engineering]: Tools and Techniques; I.7.2 [Document Preparation]: Hypertext/Hypermedia General Terms: Design Additional Key Words and Phrases: Heterogeneous hypermedia, hypermedia system architectures, open hypermedia systems, link servers, software development environments

1. INTRODUCTION This paper takes a fresh look at modeling approaches to information retrieval that have been the basis of much of the probabilistically motivated IR research over the last […], This paper takes a fresh look at modeling approaches to information retrieval that have been the basis of much of the probabilistically motivated IR research over the last 20 years. We shall adopt a subjectivist Bayesian view of probabilities and argue that classical work on probabilistic retrieval is best understood from this perspective. The main focus of the paper will be the ranking formulas corresponding to the Binary Independence Model (BIM), presented originally by Roberston and Sparck Jones [1977] and the Combination Match Model (CMM), developed shortly thereafter by Croft and Harper [1979]. We will show how these same ranking formulas can result from a probabilistic methodology commonly known as Maximum Entropy (MAXENT). Categories and Subject Descriptors: H.3.3 [Information Storage and Retrieval]: Information Search and Retrieval--retrieval models General Terms: Theory Additional Key Words and Phrases: Binary independence model, combination match, linked dependence, idf weighting, probability ranking principle

This paper introduces the concept of programming in the complex to designate the development and maintenance of complex software systems in situations where the software process and the software architecture need to change dynamically in order to cope with the impact of unpredicted and frequent environmental changes. The article proposes a systemic-cybernetic process model, which is a composition of Stafford Beer's viable system model (VSM) and Barry Boehm's spiral model. The VSM provides adaptability to the software architecture and self-organizing capability to the software process. As a result of the application of the VSM, four relevant insights are presented. Keywords software process; software architecture refactoring; software development management; managerial cybernetics; Viable System Model, INTRODUCTION Complex software systems are not a novelty. They have existed for a long time in areas such as military, aerospace and government applications. But when a company in a [...]