There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

This paper investigates the high speed nano-grooving on mono-crystalline copper by nano-end-milling and nano-peripheral-milling. The molecular dynamics method was used for simulation. The milling forces and grooving quality were analysed in detail. The comparison showed that peripheral-milling requires a higher force, but the milled groove has a better quality. Nevertheless, both the milled groove subsurfaces are free of major dislocations.

Atomic-Scale Grooving on Copper: End-Milling vs. Peripheral-Milling

The 3ω method is an attractive technique for measuring the thermal conductivity of materials; but it cannot characterise high thermal conductivity ultra-thin film/substrate systems because of the deep heat penetration depth. Recently, a modified 3ω method with a nano-strip was specifically developed for high thermal conductivity thin film systems. This paper aims to evaluate the applicability of this method with the aid of the finite element analysis. To this end, a numerical platform of the modified 3ω method was established and applied to a bulk silicon and an AlN thin-film/Si substrate system. The numerical results were compared with the predictions of theoretical models used in the 3ω method. The study thus concluded that the modified 3ω method is suitable for characterising high thermal conductivity ultra-thin film/substrate systems.

https://www.mdpi.com/2079-6412/9/2/87/pdf

Finite Element Analysis of the 3ω Method for Characterising High Thermal Conductivity Ultra-Thin Film/Substrate System

This chapter provides a comprehensive review on machining of particulate-reinforced metal matrix (PRMMCs). Based on a detailed discussion on the material properties and applications of PRMMCs, and the effects of cutting tools and machining parameters on machined surface integrity and tool wear, the chapter pointed out that machining optimization of PRMMCs toward high surface integrity is still a challenge. The main problem lies in that the complicated interactions between the brittle particles, soft matrix, and cutting edge bring about particle fracture, particle–matrix debonding, matrix tearing, and severe wear of cutting tools. The chapter then reviewed the numerical modeling of PRMMCs, including the methods using equivalent homogeneous material and multiphase (MP) techniques. It demonstrated that cutting simulations with MP can predict the cutting forces, material removal processes, surface generation, and temperature rise in the machining of PRMMCs.

Advances in machining of particulate-reinforced metal matrix composites

Potassium dihydrogen phosphate (KDP) crystals are important materials in high-energy laser systems. However, because these crystals are brittle and soft, machining-induced defects often emerge in KDP components. This study aimed to investigate the material removal mechanisms and characteristics of KDP during nanoscratching using Berkovich, spherical, and conical indenters. We found that KDP surface layers could be removed in a ductile mode at the micro/nanoscale and that dislocation motion was one of the main removal mechanisms. Removal characteristics are related to the stress fields generated by indenter geometries. The spherical indenter achieved a ductile removal mode more easily. The lateral force of nanoscratching increased with an increase in the normal force. The coefficient of friction (COF) followed the same trend as the lateral force when spherical and conical indenters were used. However, the COF was independent of the normal force when using a Berkovich indenter. We found that these COF variations could be accurately described by friction models.

Liangchi Zhang

Papers

Atomic-Scale Grooving on Copper: End-Milling vs. Peripheral-Milling

Finite Element Analysis of the 3ω Method for Characterising High Thermal Conductivity Ultra-Thin Film/Substrate System

Advances in machining of particulate-reinforced metal matrix composites

Material removal mechanisms and characteristics of potassium dihydrogen phosphate crystals under nanoscratching

Atomistic Deformation of Silicon under Triaxial Stresses