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 deformation in monocrystalline silicon subjected to single-point cutting with the cutting speed up to 46.78 m/s, the depth of cut of 2 μm, and the feed rate of 5 and 30 μm/rev. Raman spectroscopy and transmission electron microscopy were used to characterize the subsurface damages. It was found that the increase of either the feed rate or cutting speed increases the thickness of amorphous layer and penetration depth of dislocations. At the feed rate of 30 μm/rev and cutting speed of 12.48 m/s, a new dislocation system was initiated. An unknown peak was detected by Raman spectroscopy, which may indicate an unknown Si phase.

Deformation in mono-crystalline silicon caused by high speed single-point micro-cutting

A nanometric surface finish of PCD composites has been achieved efficiently with the aid of dynamic friction polishing. This paper investigates the micro-structural evolution in PCD composites at different polishing stages using the rapid Raman mapping technique. It was found that transformed amorphous non-diamond carbon and amorphous graphite phases appeared in surfaces during polishing, indicating the evolution route of phase transformations. In a completely polished surface, pristine diamond phase was predominant within the grain areas, while SiC and Si distributed more strongly along grain boundaries. No amorphous non-diamond carbon or graphite phase was detected. The composites maintain a high quality after polishing.

Quality Verification of Polished PCD Composites by Examining the Phase Transformations

On the dependence of surface undulation on film thickness

High Velocity Impact Responses Of Engineered Cementitious Composite Panels

This paper developed an effective multiscale method for analysing the deformation of NanoElectroMechanical (NEM) switches based on carbon nanotubes. The switches were simplified to beam systems with loads calculated from three-coupled energy domains: the electrostatic energy domain, the elastostatic energy domain, and the van der Waals energy domain. A meshless formulation was then used to discretise the switches to establish the non-linear system of equations for solution. The pull-in voltage characteristics of the fixed-fixed and cantilever nanoswitches based on the single-walled nanotube and the double-walled nanotube are analysed. A parametric comparison with the results in the literature showed that the method developed in this paper is very effective.

Liangchi Zhang

Papers

Deformation in mono-crystalline silicon caused by high speed single-point micro-cutting

Quality Verification of Polished PCD Composites by Examining the Phase Transformations

On the dependence of surface undulation on film thickness

High Velocity Impact Responses Of Engineered Cementitious Composite Panels

A simple method for analysing the deformation of nanoelectromechanical switches based on carbon nanotubes