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

An overview of the extended/generalized finite element method (GEFM/XFEM) with emphasis on methodological issues is presented. This method enables the accurate approximation of solutions that involve jumps, kinks, singularities, and other locally non-smooth features within elements. This is achieved by enriching the polynomial approximation space of the classical finite element method. The GEFM/XFEM has shown its potential in a variety of applications that involve non-smooth solutions near interfaces: Among them are the simulation of cracks, shear bands, dislocations, solidification, and multi-field problems. Copyright © 2010 John Wiley & Sons, Ltd.

The extended/generalized finite element method: An overview of the method and its applications

Review of State of Art of Smart Structures and Integrated Systems

A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

The paper provides a state of the art review of guided wave based structural health monitoring (SHM). First, the fundamental concepts of guided wave propagation and its implementation for SHM is explained. Following sections present the different modeling schemes adopted, developments in the area of transducers for generation, and sensing of wave, signal processing and imaging technique, statistical and machine learning schemes for feature extraction. Next, a section is presented on the recent advancements in nonlinear guided wave for SHM. This is followed by section on Rayleigh and SH waves. Next is a section on real-life implementation of guided wave for industrial problems. The paper, though briefly talks about the early development for completeness,. is primarily focussed on the recent progress made in the last decade. The paper ends by discussing and highlighting the future directions and open areas of research in guided wave based SHM.

https://iopscience.iop.org/article/10.1088/0964-1726/25/5/053001/pdf

Guided wave based structural health monitoring: A review

We present a mathematical modelling and analysis of reflection grating etched Si AFM cantilever deflections under different loading conditions. A simple analysis of the effect of grating structures on cantilever deflection is carried out with emphasis on optimizing the beam and gratings such that maximum amount of diffracted light remains within the detector area.

Analysis of grating inscribed micro-cantilever for high resolution AFM probe

A mesoscopic model to analyze various effects of electroactive and flow related properties in piezoelectric copolymer composite thin film has been developed in this paper. A three-phase composite with piezoelectric particulate phase, electroactive polymer phase and graft polymer-matrix phase is considered. The homogenized constitutive model takes into account the local transport of cations in polymer, electrostriction and anhysteretic polarization. A finite strain description is given which includes the mesoscopic dispersion of copolymer chains. Finite element simulation is carried out by considering a P(VDF-TrFE)-PZT-Araldite thin film. Analysis of the results indicate that an increasing copolymer content substantially changes the deformation pattern in the film.

Mesoscopic dynamics of piezoelectric copolymer thin films

Modelling and Design of Nanostructured Optoelectronic Devices

In this contribution we propose an iterative scheme for the solution of the coupled Poisson-Schroedinger system in 
a self-consistent manner. The developed methodology allows us to analyze the combined effects of piezoelectricity, 
spontaneous polarization, and the charge density in low-dimensional semiconductor nanostructures. These effects 
are analyzed here on an example of a wurtzite type semiconductor heterojunction. It is shown that such effects 
may influence substantially the electronic states and quasi-Fermi level energies of the nanostructures, in particular 
when compared to one-step calculations based on the conventional schemes. A major emphasis is given to two 
different types of mechanical boundary conditions.

Analysis of low-dimensional semiconductor nanostructures with a self-consistent iterative scheme

A computational framework is developed to investigate the in∞uence of combustion induced follower force (thrust) and mass variation on the launch vehicle dynamics and stability. A detailed mechanics based mathematical model of a moving ∞exible vehicle is used. Coupling among the rigid-body modes, the longitudinal vibrational modes and the transverse vibrational modes are considered. The governing difierential equations are nonlinear and coupled with respect to rigid body displacements and elastic displacements. The structural dynamic modes of the vehicle are modifled due to the instantaneous states of the vehicle centre of mass velocity and acceleration. Eigenvalues of the vehicle are determined in order to analyze the stable regimes. Numerical simulations are carried out for a typical vehicle conflguration to determine the instability regimes with vehicle speed and chamber pressure as the parameters. Phenomenon of static instability (divergence) and dynamic instability (∞utter) are observed for certain parameters.

D. Roy Mahapatra

Papers

Analysis of grating inscribed micro-cantilever for high resolution AFM probe

Mesoscopic dynamics of piezoelectric copolymer thin films

Modelling and Design of Nanostructured Optoelectronic Devices

Analysis of low-dimensional semiconductor nanostructures with a self-consistent iterative scheme

Influence of Combustion Coupled Follower Force and Mass Sensitivity on Launch Vehicle Stability