Advanced Computer Systems Research Articles

Monte-Carlosimulation of dislocation networks using the message passing interface

The dynamic behaviour of one-dimensional lattice defects in metallicmaterials is responsible for most of themetals' mechanical properties. This behaviour is determined by all theinteraction mechanisms of dislocations with other lattice defects such as further dislocations, precipitations and grainboundaries. A two-dimensional simulation model implementing thesemechanisms based on a Monte-Carlo method for an N-body dislocationsystem is presented. The influences of temperature and external stresscan also be taken into account. In this model, the different defects will be reduced to a polymorphic structure according to the object-oriented paradigm. Toimprove computing performance, the model was parallelized for multiprocessor machines in collaboration with the Edinburgh ParallelComputing Centre (EPCC) under the European Union TRACS programme (Training and Research on Advanced Computing Systems).Results are discussed under consideration of different parameters.

Multiconverter Power Systems and Their Applications

As the power systems evolve to contain more and more solid-state devices, a new type of power system emerges. We call this solid-state, silicon rich, silicon intensive, power electronics based, or, as is named in this paper, multiconverter power systems. In these systems, solid-state switching power converters are extensively used for generating, distributing, and utilizing of electrical energy throughout the system. Different converters, such as DC/DC choppers, DC/AC inverters, AC/AC cycloconverters, and AC/DC rectifiers, are used in source, load, and distribution subsystems to provide power at different voltage levels and both DC and AC forms. Most of the loads are also in the form of power electronic converters and motor drives. These systems have a broad variety of applications from small multiconverter power systems, such as automotive power systems, Electric and Hybrid Electric Vehicles (EV & HEV), advanced industrial electrical systems, telecommunications, and terrestrial computer systems with a few converters, to large systems, such as International Space Station (ISS), spacecraft, modern aircraft, submarine, and More Electric Ship (MES) power systems with many converters. Furthermore, these unconventional power systems have unique characteristics, dynamics, and stability problems that are just beginning to be appreciated. In this paper, we take a closer look at multiconverter power systems and address the fundamental problems faced in these systems. We also propose the multiconverter power systems as a new area of specialized research, which will have benefits in many applications.

Virtual Technology Based Associative Integration of Modeling of Mechanical Parts

Advanced application of powerful computer tools at engineering design of advanced products related activities means creating integrated product models in advanced computer systems. Leading application oriented master model concepts and standards as STEP serve this purpose. Engineers are working simultaneously on product design. Results of engineering decisions are analyzed for loads, aesthetics and manufacturability. Product design, results of analyses, processes of manufacturing of parts and much more are described in integrated product model. This model is accessed by several engineers simultaneously and is communicated with other engineering design environments. Because most of prototype development activities are being moved into computer systems, advanced modeling is often cited as virtual pro-, totyping. This paper summarizes and relates some advanced modeling approaches and methods to emphasize main trends in fulfilling demands for modeling tools in the early 21th century. As one of the key issues a manufacturing process model associative with form feature based part model is introduced. This model was proposed by the authors. The motivation is that low level integration of design and manufacturing of mechanical parts is still a main drawback of efficient application of expensive modeling systems. The proposed method ’allows for creating part models simultaneously with their analysis of machineability. In this paper chapter 2 outlines the scene of modeling based decision making of engineers as well as levels of product model creation. Chapter 3 explains the prevailing modeling principles, while chapter 4 emphasizes structure descriptions. In chapter 5 the proposed associative, Petri net model representation based manufacturing process modeling and its potential applications are explained are detailed. Two additional key subject areas are discussed in chapter 6 and chapter 7, namely effects of globalization on modeling and product data management. The main aspect of discussion is model and communication based group work of engineers.

Simulation des Verfestigungsverhaltens von Metallen unter thermomechanischen Einflüssen

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CAD/CAM System for Insole Production

Impressive strides in medicine enhanced a necessity for highly advanced computer systems which would provide measurement and visualization aids with a high degree of accuracy, and high standards for planning and application of specific medical procedures. Orthopaedy, as amedical branch, was enriched for anew approach in design and application of orthoses and prostheses, CAD/CAM. This paper gives an overview about biomechanical characteristics of the foot, which directly implies the features of the future insole. Because of the unity of each foot, the principle of universality, i.e. mass production of insoles, does not give the expected results. Therefore, the advantage is given to production of insoles according to the clinical and pedobarographic finding of the individual. The paper presents the phases in production of insoles by applying CAD/CAM. It describes the developed CAD/CAM system, enabling efficient interfacing of all production phases. The system is developed by applying Open GL, Visual C++ and Visual Basic. It consists of five modules: data base, module for processing and presentation of measured data, module for presentation of the foot RTG pictures, module for modification and adjustments of standardized insoles, and postprocessor.

An advanced digital image-capture computer system for gross specimens: a substitute for gross description

The description of macroscopic appearances of surgically excised specimens together with the sites of specimen sampling form an important component in the documentation of a histopathology specimen. Unfortunately, accuracy of description depends on the vocabulary and descriptive prowess of the pathologist which means that the result can be variable. Transcription of the dictated word also takes time and involves typists. We developed a user-friendly, high-resolution image capture system that will supplement word description of macroscopic specimens and has the potential to replace it completely. It also provides the opportunity of revisiting traditional methods of documenting specimens with words, allowing the production of more relevant and user-friendly reports containing information relevant to clinical management and supplemented by high-resolution digital images. The accompanying Windows-based software has capabilities of generating the entire histopathology report and allows rapid retrospective searches through any one of several common search parameters. The stored images form a powerful database for teaching and research. Connection to remote transmission facilities allows teleconferencing and telepathology consultations.

Just curious: An interview with John Cocke

A legend in computer architecture and perhaps best known as a pioneer of ideas that led to reduced instruction set computing, John Cocke has designed machines that still influence processor design today. In conjunction with his winning the inaugural Seymour Cray award, Computer interviewed Cocke in his Westchester, New York, home. Computer talked to Cocke about how he became interested in computers and the projects for which he is famous: the IBM Stretch, Advanced Computer System (ACS), and the 801, RS6000, and PowerPC processors. The project to build the 801 (one of the first RISC processors) used the code-name America. Cocke recounts how he chose the name based on a story about the first America's Cup yacht race. In the interview, Cocke expresses his opinions on the prospects for parallel computing, quantum computing, and future computer architectures.

Helping operators improve plant performance

A process assistance system empowers operators to make decisions and take ownership of the plant during their shifts.The City of Austin (Texas) Water and Wastewater Utility consistently produces drinking water of the highest standards. But with the development of more and tougher regulations, water treatment has become more complex for operators. Utility managers recognized that although it is necessary to provide advanced computer systems, instrumentation, and traditional operations training, these elements alone are not sufficient to meet the utility's stringent internal optimization goals. Operators also need to be able to recognize and respond promptly to developing process problems. Utility managers realized that operators would benefit from readily available plant‐specific process guidance and envisioned a process assistance system (PAS). Written in Web‐page format, the PAS is designed to help operators interpret data and improve their decision‐making skills. It was developed through in‐depth investigations of operators' actions and treatment decisions during routine and nonroutine operations. The PAS will also be used as a tool for training, performance assessment, and operator accountability.

A Disaster-Tolerant Widely Distributed File System Using Optical Disk Libraries

We have developed a disaster-tolerant widely distributed data-backup file system that uses optical disk libraries and either simple or advanced small computer system interface (SCSI) extension equipment. The latter includes a redundant arrays of inexpensive disks (RAID) function. To evaluate the basic performance of the developed system, we first used the simple SCSI extension equipment to investigate the effect of the SCSI command-queuing function used in the local SCSI target module and found that it increases the processing speed. We then examined the effect of delay due to the wide distribution and found that read/write throughput was not affected up to distances of 10 km. Next we compared the performance of the backup system using both types of SCSI extension equipment with that without extension equipment. We found that the write speed is about the same for both, but the read speed is slower with the SCSI extension when the data size exceeds 100 kB. Using the advanced equipment to distribute the data to multiple disks solved the problem of non matching read speeds to a certain extent. A backup system using the advanced equipment was applied to a database system by using a database benchmark test program.

A numerical study for global atmospheric transport–chemistry problems

Atmospheric air quality modeling relies in part on numerical simulation. Required numerical simulations are often hampered by lack of computer capacity and computational speed. This problem is most severe in the field of global modeling where transport and exchange of trace constituents are studied in the whole of the global troposphere/stratosphere. Studies in this field easily lead to computations with millions of unknowns over long time spans. Use of fast, tailored numerical algorithms implemented on the most advanced computer systems is then needed for making real progress. This paper is devoted to a performance study of algorithms developed for solving global atmospheric transport–chemistry problems. The algorithms are applied within two different operator splittings and are vectorized and parallelized on a Cray C90. For the performance study we use a constructed, three-space-dimensional model problem, containing advection, vertical turbulent diffusion and chemical reactions. This numerical model problem is presented as a benchmark on which other algorithms and implementations can be tested. The benchmark problem together with all the algorithm software is available through World Wide Web. In the context of operator splitting, particular attention is paid to the issue of solving chemistry and vertical turbulent diffusion coupled or uncoupled.

Configuration and coordination of virtual production networks

Following the actual discussion concerning modern production concepts, the term “virtual production” or “virtual enterprise” plays an increasingly important role. The idea of virtual enterprises is to implement modern management trends like “concentration on core competencies”, “distributed production” and “maximal customer orientation” by the application of advanced computer and telecommunication systems and services like “global networking” or “groupware systems”. The objective is to establish a certain kind of a “Best of everything Organization” by a synergetic combination of core competencies of single partners (centers of competence) in order to perform a given business project to a maximum degree of customer satisfaction. Important features are a distinct form of network organization in combination with a high degree of organizational flexibility. Taking into account Williamson's theory of transactions costs, virtual enterprises can be interpreted as a certain kind of an intermediate organizational form between the institutional poles: market and hierarchical structured enterprises. According to this an evaluation will be given on the basis of transaction costs. In the following section structural and process-orientated questions of virtual production systems are formulated. From the viewpoint of production science, especially the allocation of sub-tasks to adequate project partners and the harmonization of distributed production processes in a network of independent companies seems to be very interesting. Principally, the decision support systems for such problems can be based on hierarchical or distributed control strategies. The characteristics of virtual production systems imply the application of decentralized approaches (e.g. multi-agent systems). A very interesting approach in this context is the application of distributed problem-solving strategies like contract networks.

Advanced Transport Telematics System for Ports/The Piraeus Case

Abstract Aiming at enhancing the efficiency of transport systems and reducing the level of pollution,Advanced Transport Telematics(ATT) systems have been introduced, as they become feasible, due to rapid technological advances in computer systems, electronics and communications. The city of Piraeus was one of the initiators that used an integrated approach to traffic management and provision of travel and traffic information in order to improve the network efficiency and encourage the use of public transport. Information dissemination is planned to satisfy the requirements of travellers on board ferries and travellers approaching and leaving the port by car or public transport. The system architecture, the benefits, and the gained experience from the design and implementation of ATT systems for ports and especially the Piraeus case, are going to be presented in the paper.

An Inheritance System with Regular Expressions and IS-A Relation

In this paper, we propose an inheritance system for knowledge-bases in which IS-A relation and IS-NOT-A relation are specified on the domain extended by dot notation ‘.’. Due to the simplicity of the framework, we can obtain several computational advantages including the following: (1) IS-A relation and IS-NOT-A relation are determined in polynomial time. (2) Satisfiability of a given knowledge-base is also determined in polynomial time. (3) Set-at-a-time queries are completely answered by regular expressions. (4) Regular expressions are also used for specifications of knowledge-bases. Consequently, we can achieve advanced reasoning by the computational operations on regular sets using union, intersection, and difference. Furthermore, the obtained results can be incrementally reused to specify new knowledge-bases. Several applications of the proposed inheritance reasoning mechanism in advanced computer systems are also demonstrated.

Preoperative and Postoperative Care for Laser Resurfacing Patients

Steven M. Hoefflin, MD, Santa Monica, CA, is a board-certified plastic surgeon and ASAPS member. The age of advanced technologic gadgetry has certainly arrived in plastic surgery. One cannot open a journal or attend a meeting without exposure to advanced office computer systems, new digital photography, higher resolution endoscopy equipment, supercharged monitors, emerging ultrasonic liposuction units, and precision-guided lasers. However, is this new technology outpacing adequate science? CO2 laser resurfacing is a positive technology that works, but will it prove to be better than the chemical peel or dermabrasion in the long run? Sufficient scientific data are not yet available to answer this question. The CO2 laser is a “controlled burning” instrument. The manufacturer's literature and early certification courses claimed that heat is not a significant factor, whereas common sense and emerging scientific studies tell us that it is. The laser vaporizes tissue at 100° C and shrinks collagen at 60° C; this is how it produces its benefits. Yet unexpected burns are possible, even in the best of hands. What is happening between the margin of 100° C superficially and 60° C in the dermis? I believe that prolonged cutaneous redness is due to second-degree dermal …

Criminal investigation systems: the growing dependence on advanced computer systems

Methods of criminal investigation are often heavily dependent on the coordinated activities of people who collect, evaluate and analyse substantial quantities of information. Computing techniques are being increasingly employed to support such work and several specialised systems have been developed during the past decade to meet the needs of this technically demanding market. Since most existing and emerging standard database systems possess neither the requisite functionality, nor acceptable performance, the investigative field is one that is becoming a forcing house for new concepts and new technology.

Using Existing Data Sets to Study Aging and the Elderly: An Introduction

RÉSUMÉLe dévéloppement des systèmes d'information a permis la création de vastes banques de données informatisées détaillées, dont bon nombre contiennent des renseignements pertinents à la recherche sur les personnes âgées et le vieillissement. Cet article cite plusieurs types de banques de données exhaustives et fournit des exemples de chacun. Il présente ensuite les points forts et les points faibles des études menées à l'aide de données déjà existantes, puis souligne des stratégies pour l'analyse de données secondaires. Les banques de données déjà en place exigent beaucoup d'efforts dans la compilation de données individuelles et offrent d'immenses possibilités pour répondre aux questions importantes en matière de recherche sur le vieillissement.

P73 Advanced computer systems for resuscitation and intensive care

P73 Advanced computer systems for resuscitation and intensive care

Fault trees and Markov models for reliability analysis of fault-tolerant digital systems

Reliability analysis of fault tolerant computer systems for critical applications is complicated by several factors. In this paper, we discuss these modeling difficulties and describe and demonstrate approaches to handling them. Three important techniques characterize our approach. First, behavioral decomposition separates the system failure modes specification from the recovery process specification. Second, a fault tree representation of the system failure modes is converted to an equivalent Markov model, to which the recovery models are added automatically. Third, the fault tree to Markov chain conversion allows the definition of new dynamic fault tree gates to capture the sequence dependent failure modes that are often associated with advanced fault tolerant systems. Two advanced fault tolerant computer systems are described, and fault tree models for their analysis are presented. HARP (the Hybrid Automated Reliability Predictor) is a software package developed at Duke University and NASA Langley Research Center that is used to analyze the example systems.

Evaluation of the Ashtekar variables for any given metric using the algebraic computing system STENSOR

The authors develop a program to evaluate the Ashtekar variables and subsequently the Gauss law, the Hamiltonian and the momentum constraint for any given metric. This is possible using the advanced algebraic computing system STENSOR. Given any metric and a related triad the program takes N=-1/g00, Ni=g0i etc and evaluates the Ashtekar variables and the constraints. They run the program for the Schwarzschild metric and produce the related quantities.

Opinion: Learning in the ‘Neural’ Organization

This paper considers an approach to organizational learning as a result of research carried out by the author as part of a doctoral study in the field of career development and organizational politics. This study described the forms of communication that operate within organizations, the labels attached to those methods and the way in which they are used to further the careers of aspiring professionals. This led to the recognition of methods of communication described as ‘neural’ networks after the models being developed by advanced computer programmers into the operation of the mind. In trying to map the complexity of the brain they have developed theories that describe the information channels in advanced computer systems in the form of neural networks. Such terms can be applied to the actual communication channels used within organizations. This paper therefore starts with an overview of what is meant by the term and then develops the theme by considering the impact of such networks on the learning pro...