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

Statistics for Spatial Data.

THE author of this book ranks as the foremost American worker on insect morphology. His contributions on the subject are notable for their clarity and originality of thought, and the appearance of a volume, embodying his ideas in comprehensive form, is sure of a hearty welcome. In its preparation, Mr. Snodgrass has incorporated the results of much first-hand study with those of many recent investigators in the same field. He has produced an outstanding book wherein knowledge of facts is combined with that of function and, at the same time, theoretical conceptions of the origins and relationships of organs and parts are not overlooked. Principles of Insect Morphology
 By R. E. Snodgrass. (McGraw-Hill Publications in the Zoological Sciences.) Pp. ix + 667. (New York and London: McGraw-Hill Book Co., Inc., 1935.) 36s. net.

Principles of Insect Morphology

We have induced large elastic strains in ropes of single-wall carbon nanotubes, using an atomic force microscope in lateral force mode. Freely suspended ropes were observed to deform as elastic strings with tension proportional to elongation. Ropes were elastically deformed over >10 cycles without showing signs of plastic deformation. The maximum strain observed, 5.8±0.9%, gives a lower bound of 45±7 GPa for the tensile strength (specifically, yield stress) of single-wall nanotube ropes.

Elastic strain of freely suspended single-wall carbon nanotube ropes

The lens of Anabus testudineus is spherical. Scanning electron microscope reveals that the lens is composed of lenticular fiber cells which possess various functional apparatus. The structure of the lens suggests a semi – aquatic mode of vision. The structure also suggests that the unabsorbed portion of the light which enter the eye are scattered by the lens.

Ultramicroscopic structure of the lens of Anabas testudineus and its significance

The quantification of uncertainty in composite structures has intuitively significant threat to ensure structural reliability. Due to inherent complexities, composite structures are difficult to manufacture accurately according to its exact design specifications resulting in unavoidable uncertainties. Typical uncertainties are inadvertently induced due to intralaminate voids, incomplete curing of resin, excess resin between plies, excess matrix voids, porosity, variations in material properties and fibre parameters. In general, random field models are extensively used to represent a spatially varying function. Different probabilistic approaches (Monte Carlo simulation, perturbation methods, random matrix, and generalized polynomial chaos with Karhunen-Loève expansion) are employed for composites. In a probabilistic setting, uncertainty associated with the system parameters can be modelled as random variables or stochastic processes using the so-called parametric approach. But in real-life situation due to the availability of limited sample data (crisp inputs), it will be more practical or realistic to follow non-probabilistic approach rather than probabilistic approach. In the present study, fuzzy approach is introduced to carry out the uncertainty propagation in natural frequencies of laminated composite plates using Gram-Schmidt Polynomial Chaos (PC). The proposed PC fuzzy model is integrated with finite element to predict the possible two extreme bound of responses for different degree of fuzziness. The fuzzy variable is represented as a set of interval variables via membership function. The most significant input parameters are identified and then fuzzified. Fuzzy analysis of the first three natural frequencies for typical laminate configuration is presented to illustrate the results and its performance.

Uncertainty quantification of dynamic characteristics of composites – a fuzzy approach

This paper presents the effect of temperature on stochastic natural frequencies of cylindrical shells, composed of functionally graded materials (FGM) by using machine learning quadratic Support Vector Machine (SVM). An eight noded isoperimetric quadratic element is considered for the finite element formulation. The power law is employed to construct the material modelling of FGM cylindrical shells. Monte Carlo Simulation (MCS) is carried out in conjunction with stochastic eigenvalue solution. In the present study, zirconia (ceramic) and aluminium (metal) are considered to compose the FGM. The machine learning SVM model is constructed to reduce the computational iteration time and cost and validated with the traditional MCS model. The statistical analyses are conducted to portray the first three modes of frequencies. The results show that due to the increase of the temperature, the values of both deterministic as well as the stochastic mean of the first three natural frequencies decreases along with the decrease in sparsity. Sensitivity analysis is also carried out to enumerate the significant important input parameters contributing to influence the output quantity of interest (QoI). The statistical results obtained are the first known results.

Support Vector Model Based Thermal Uncertainty on Stochastic Natural Frequency of Functionally Graded Cylindrical Shells

Conventional indoor rearing of muga silkworm (Antheraea assamensis) by tray-feeding (horizontal feeding posture), associated with low food consumption was found to cause a number of abnormalities in the mid-gut cell microvilli. In indoor-reared horizontally fed worms the density of microvilli was found to be less than that of the control. In the longitudinal sections, microvilli showed abnormalities in the form of irregular arrangements, discontinuity and less thickness than that of normal worms. Some of the microvilli showed fusion at places and swelling at the tip. In transverse sections, the microvilli was found to be remarkably disturbed. The continuity of the membrane was lost in some of the microvilli. The worms fed at vertical posture, however, did not exhibit any of these abnormalities and were found to be normal.

Conventional indoor rearing leads to abnormalities in the ultrastructure of muga silkworm (Antheraea assamensis) mid-gut cell microvilli.

Bleached Sulphite Pulp Mill Effluents Adversely Affect Cellular and Subcellular Features of Anabas testudineus Fish Tissues: An Electron Microscopic Analysis

Sudip Dey

Papers

Ultramicroscopic structure of the lens of Anabas testudineus and its significance

Uncertainty quantification of dynamic characteristics of composites – a fuzzy approach

Support Vector Model Based Thermal Uncertainty on Stochastic Natural Frequency of Functionally Graded Cylindrical Shells

Conventional indoor rearing leads to abnormalities in the ultrastructure of muga silkworm (Antheraea assamensis) mid-gut cell microvilli.

Bleached Sulphite Pulp Mill Effluents Adversely Affect Cellular and Subcellular Features of Anabas testudineus Fish Tissues: An Electron Microscopic Analysis