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

Streamline upwind/Petrov-Galerkin formulations for convection dominated flows with particular emphasis on the incompressible Navier-Stokes equations

From the Publisher:
This self-contained introduction to practical robot kinematics and dynamics includes a comprehensive treatment of robot control. Provides background material on terminology and linear transformations, followed by coverage of kinematics and inverse kinematics, dynamics, manipulator control, robust control, force control, use of feedback in nonlinear systems, and adaptive control. Each topic is supported by examples of specific applications. Derivations and proofs are included in many cases. Includes many worked examples, examples illustrating all aspects of the theory, and problems.

Robot dynamics and control

A higher-order shear deformation theory of laminated composite plates is developed. The theory contains the same dependent unknowns as in the first-order shear deformation theory of Whitney and Pagano (1970), but accounts for parabolic distribution of the transverse shear strains through the thickness of the plate. Exact closed-form solutions of symmetric cross-ply laminates are obtained and the results are compared with three-dimensional elasticity solutions and first-order shear deformation theory solutions. The present theory predicts the deflections and stresses more accurately when compared to the first-order theory.

A Simple Higher-Order Theory for Laminated Composite Plates

Non-Self-Adjoint Differential Operators

Vibration suppression of laminated composite plates using magnetostrictive inserts

Polycrystalline materials consist of grains (crystals) oriented at different angles resulting in a heterogeneous and anisotropic mechanical behavior at that micro-length scale. In this study, a nov...

Identification of the 3D crystallographic orientation using 2D deformations

Heat Transfer, Convective: Porous Materials

: Numerical, experimental, and hybrid combinations of these methods, were used to study plane contact problems. The experimental program used moire interferometry to determine in-plane displacement fields near the contact boundaries of pin-loaded aluminum and graphite-epoxy plates. The experiments closely modeled two dimensional behavior and introduced zero-thickness gratings (for the aluminum plate). The experimental data were reduced by means of a localized hybrid analysis which used the experimental displacement data as input to a finite element analysis of selected zones of interest. The stress distributions obtained were generally consistent with those of published analytical and experimental studies but the detailed frictional phenomena were found to be very localized and somewhat irregular. The composite plate program featured a failure analysis based upon the experimentally determined stress distributions. These distributions were combined with a maximum stress failure criterion to predict the mode and location of the failure. The results of an earlier experiment were used to assess the accuracy of a general finite element algorithm for plane elastic problems. On the basis of this comparison refinements to the solution methodology were made. Keywords: Matrix cracking, Composite plates, Aluminum, Contact, Moire interferometry, Fringe patterns, Hybrid techniques elasto-plastic analysis, Eulerian-Lagrangian formulation, Finite element analysis.

J. N. Reddy

Papers

Non-Self-Adjoint Differential Operators

Vibration suppression of laminated composite plates using magnetostrictive inserts

Identification of the 3D crystallographic orientation using 2D deformations

Heat Transfer, Convective: Porous Materials

Friction Phenomenon in Contact Stress Problems