Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

This paper gives the main definitions relating to dependability, a generic concept including a special case of such attributes as reliability, availability, safety, integrity, maintainability, etc. Security brings in concerns for confidentiality, in addition to availability and integrity. Basic definitions are given first. They are then commented upon, and supplemented by additional definitions, which address the threats to dependability and security (faults, errors, failures), their attributes, and the means for their achievement (fault prevention, fault tolerance, fault removal, fault forecasting). The aim is to explicate a set of general concepts, of relevance across a wide range of situations and, therefore, helping communication and cooperation among a number of scientific and technical communities, including ones that are concentrating on particular types of system, of system failures, or of causes of system failures.

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Basic concepts and taxonomy of dependable and secure computing

Basic Concepts and Taxonomy of Dependable and Secure Computing

* Starting from Need* Evolution of the Toyota Production System* Further Development* Genealogy of the Toyota Production System* The True Intention of the Ford System* Surviving the Low-Growth Period

Toyota production system : beyond large-scale production

Fully updated and revised with more practical emphasis and more extensive use of case studies, this edition provides a comprehensive description of the main probabilistic methods employed in reliability and risk assessment, particularly fault tree analysis and failure mode, and effective analysis and their derivatives. Self-contained, each chapter focuses on a single subject or method and illustrates it with worked examples. The final chapter features four major case studies from recent projects to show how the methods have been applied to identify and quantify the risk and reliability characteristics against specific performance requirements. Focusing on the risk and reliability assessment of process plants, this book serves as a comprehensive reference to powerful analysis techniques for design, operation, and regulatory engineers involved directly with the safety and availability assessment of potentially hazardous process plants. It also serves as a text for undergraduate, graduate, and incompany courses and training. Contents: Introduction to Reliability and Risk Assessment; Reliability Mathematics; Qualitative Methods; Failure Mode and Effects Analysis; Quantific of Component Failure Probabilities; Reliability Networks; Fault Tree Analysis; Common Cause Failures; Maintainability; Markov Analysis; Simulation; Reliability Data Collection and Analysis; Risk Assessment; Case Study 1: Quantitative Safety Assessment of Ventilation Recirculation System in an Undersea Mine; Case Study 2: Failure Mode and Effects Criticality Analysis of Gas Turbine System; Case Study 3: In-Service Inspection of Structural Components (application to conditional maintenance of steam generators); Case Study 4: Business-interruption Risk Analysis. Appendix A: Expectation, Variance, and Standard Deviation. Appendix B: Standard Laplace Transforms; Glossary.

Reliability and Risk Assessment

This paper is concerned with ETA (event-tree analysis) where the branch point event causes are defined using fault trees. Attention is on the nontrivial situation where there are dependencies amongst the branch point events. The dependencies are due to component-failures in more than one of the fault trees. In these situations the analysis methods based on traditional FTA (fault-tree analysis) are inaccurate and inefficient. The inaccuracies are not consistent across the outcome events. If frequency predictions calculated in this way are then used in a risk assessment then the relative risks would be distorted and could lead to resources being used inappropriately to reduce the overall risk. A new approach using BDD (binary decision diagram) is described which addresses these deficiencies.

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John Andrews

Papers

Reliability and Risk Assessment

Event-tree analysis using binary decision diagrams

Tracking control of small-scale helicopters using explicit nonlinear MPC augmented with disturbance observers

A fault tree analysis strategy using binary decision diagrams

Phased mission modelling of systems with maintenance-free operating periods using simulated Petri nets