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

On the deformation mechanism of 6H-SiC under the nanogrinding of multiple abrasive grains

This paper investigates experimentally the edge chipping of a rock to assess the cutting performance of a conical and a pyramidal tip. It was found that the conical tip generates many radiated cracks and results in a larger amount of fine rock grains due to crashing. The size of chips produced by the pyramidal tip is bigger. It was concluded that the critical chipping energy has approximately a linear relation with h9/4 of which h is the depth of cut of the tip.

Edge Chipping of Rock: An Experimental Study

Metallic silicon nanowire and quantum dots are promising low dimensional materials for a great range of applications. A critical issue is their quality-controlled, cost-effective fabrication. This paper presents a simple method for making seamlessly integrated tunable metallic silicon nanowires and quantum dots in the subsurface of mono-crystalline silicon by mechanical scratching. The study predicted, with the aid of the molecular dynamics analysis, that arrays of stable metallic bct-5 silicon nanowires and conductive quantum dots could be produced in the subsurface of silicon by scratching the {001} surface along a ⟨110⟩ direction. The dimension and spacing of the nanowires and quantum dots can easily be controlled by adjusting the distance between scratching tips, the size of the tips, and their depth-of-cut. It was also shown that the metallic bct-5 silicon is stable under a residual octahedral shear stress of 5 to 8 GPa.

Liangchi Zhang

Papers

On the deformation mechanism of 6H-SiC under the nanogrinding of multiple abrasive grains

Edge Chipping of Rock: An Experimental Study

Tunable metallic silicon nanowires and quantum dots with tailored dimensions and spacing

Grinding of Ceramics: Strength, Surface Features and Grinding Conditions

Similarity and difference: damage in silicon caused by indentation, scratching, grinding and polishing