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

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

Effect of Temperature

Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

This chapter discusses numerical simulations of fracture and deformation of a cortical bone tissue employing an extended finiteelement method (X-FEM). The chapter first reviews the literature on available finite-element models for both macroscopic and microscopic fracture behaviours of the cortical bone tissue. It then discusses the formulation and analysis of a number of finite-element models investigating deformation and fracture of cortical bone using X-FEM at different length scales and for various loading conditions.

Modelling fracture processes in bones

http://scientiairanica.sharif.edu/article_3927_678a7b7f87d43b617b0e2bc502d9f828.pdf

Analysis of tool wear in ultrasonically assisted turning of beta-Ti-15V-3Al-3Cr-3Sn alloy

Spare parts inventories assist maintenance staff to keep equipment in operating condition. Thus the inventory level of spares has a direct bearing on machine availability, a factor that is increasingly important in capital-intensive industries. This paper presents a risk based approach for spare parts inventory optimization. At the outset, the paper highlights the unique features of maintenance inventories, such as spare parts inventories, compared to other inventories such as work- in- progress or finished product inventories. After a brief mention of the principles on which many of the current inventory management models are based and their limitations, the paper presents a risk-based methodology to spares inventory management. ‘Risk’ in the current context is the risk in monetary terms that arises when a component (spare) is not available on demand. It is the expected value of loss, i.e., the product of the likelihood of unavailability of the spare from the inventory and an estimate of the consequence(s) of that unavailability. Given a budgetary constraint and the risk profile of a number of spares, the model gives an optimal inventory of spares. By basing the inventory on the risk profile of spares, the model includes factors that are not normally considered in various other models. The ultimate aim of the methodology is to have an optimal level of spares inventory such that machine availability, to the extent it is dependent on the level of spares inventory, is maximized subject to constraints. The methodology is expected to benefit both, operational and financial managers.

A Risk Based Methodology for Spare Parts Inventory Optimisation

Needle-punched carbon/carbon composites (NP-C/Cs) are advanced materials widely used in aerospace applications. The needle-punching technique improves the integrality of carbon-fibre plies, however, it also introduces many defects, affecting the mechanical behavior of NP-C/Cs. A theoretical model of irregular beams is suggested to investigate the mechanical behavior of unidirectional needle-punched carbon/carbon composites. Stress distributions in punched and squeezed fibres and an effect of the needle-punching technology are assessed.

/pdf/theoretical-analysis-on-needle-punched-carbon-carbon-necy58tkp7.pdf

Theoretical Analysis on Needle-Punched Carbon/Carbon Composites

The properties of lead-free solders such as Sn38Ag07Cu are less understood than traditional Sn-Pb solders, as well as the factors affecting these material properties Therefore, the present paper focuses on determination of stress-strain properties for both small-scale solder joints and for bulk solder for three different strain rates The paper also analyses the obtained experimental results, and compares material properties between the solder joint and the bulk solder The reasons for the differences in the observed material properties are discussed, and their effects are separated through the use of finite-element analysis

Vadim V. Silberschmidt

Papers

Modelling fracture processes in bones

Analysis of tool wear in ultrasonically assisted turning of beta-Ti-15V-3Al-3Cr-3Sn alloy

A Risk Based Methodology for Spare Parts Inventory Optimisation

Theoretical Analysis on Needle-Punched Carbon/Carbon Composites

Size and microstructure effects on the stress-strain behaviour of lead-free solder joints