Stochastic modeling of discontinuous dynamic recrystallization at finite strains in hcp metals

We present a model that aims to describe the effective, macroscale material response as well as the underlying mesoscale processes during discontinuous dynamic recrystallization under severe plastic deformation. Broadly, the model brings together two well-established but distinct approaches – first, a continuum crystal plasticity and twinning approach to describe complex deformation in the various grains, and second, a discrete Monte-Carlo-Potts approach to describe grain boundary migration and nucleation. The model is implemented within a finite-strain Fast Fourier Transform-based framework that allows for efficient simulations of recrystallization at high spatial resolution, while the grid-based Fourier treatment lends itself naturally to the Monte-Carlo approach. The model is applied to pure magnesium as a representative hexagonal closed packed metal, but is sufficiently general to admit extension to other material systems. Results demonstrate the evolution of the grain architecture in representative volume elements and the associated stress–strain history during the severe simple shear deformation typical of equal channel angular extrusion. We confirm that the recrystallization kinetics converge with increasing grid resolution and that the resulting model captures the experimentally observed transition from single- to multi-peak stress–strain behavior as a function of temperature and rate

Maximally robust controllers for multivariable systems

Published versio

Estimates of growth, mortality, recruitment pattern and MSY of important resources from the Maharashtra coast

Based on the data collected from the year 1987 - 1991 the growth, mortality and recruitment pattern of eighteen species of fish, two species of cephalopods and four species of penaeid prawns have been presented in the present communication_ The total mortality coefficient, (Z) varied from lowest of 1.20 for O.cuvieri to a highest of 10.78 for P.stylifera. The natural mortality coefficient, (M) varied from 0.52 for T. thalassinus to 3.44 for S.crassicornis. The average annual yield of eighteen species of fish, four species of prawns and two species of cephalopods are 65,083, 38,404 and 11,373 tons as against the MSYof 83,023, 72,460 and 10,475 tons respectively. The MSY estimated for the total fish stock is 1,77,753t where as the present yield is 1,14,859t. This indicates that higher yield can be obtained by increasing the effort

Cephalopod production in India and constituent maritime states

The fishing craft and gear in which cepbalopods are obtained in India and the all India, statewise and east and west coast cephalopod production are presented. The bulk of the cephalopod catches is obtained along the west coast and trawl net accounts for major portion of landings. Maharashtra, Kerala, Tamil Nadu and Gujarat are the leading states in production

Distribution of finfish resources along southeast coast of India in relation to certain environmental parameters

This paper embodies the distribution pattern of major finfish resources along the southeast coast of India as observed during the cruises operated by FORV Sagar Sampada. A total of 16 cruises (1985-90) operated along latitude 7° 15'- 15°00' N and longitude 75°50'- 82°3r E hauled a total catch 37.5 tonnes with a catch rate of 537 kg/hr. The catch was constituted mainly by threadfin breams (43%), perches (14%), barracudas (9.72%), carangids (8.56%) and elasmobranchs (4.81%). Seasonally higher catch rates were obtained during July- September period. Depth range of 60 - 80 m had denser population of finfish resources. Water temperature and salinity appeared to influence the distribution of major finfishes more than dissolved oxygen. Groups such as threadfin breams were found preferring cooler waters of Wadge Bank area, while barracudas appear to occupy warmer waters of Gulf of Mannar

Study of malaria in febrile patients attending tertiary health care center and evaluation of peripheral smear examination, quantitative buffy coat and rapid diagnostic test in the diagnosis of malaria

Background: The objective was to study the prevalence of malaria in febrile patients attending the hospital and to evaluate peripheral smear examination, quantitative buffy coat and rapid diagnostic test in the diagnosis of malaria.Methods: The study group includes 208 patients presenting with fever with chills and rigor and other suggestive symptoms of malaria attending the tertiary care center. 5 ml of venous blood was collected in ethylene diamine tetra acetate (EDTA) tube from each patient and the samples were processed for peripheral blood smear examination, quantitative buffy coat (QBC) and antigen detection by rapid diagnostic test (RDT).Results: Out of 208 suspected cases of malaria, 3 (1.44%) were positive for malaria and 205 (98.55%) were negative, the prevalence of malaria was found to be 1.44%. Of total 208 cases tested, 3 cases (1.44%) were positive for malaria by peripheral blood smear examination and by QBC and with rapid diagnostic test only 2 cases (0.96%) were positive. P. vivax was detected in all 3 positive cases.Conclusions: Peripheral smear examination is considered as gold standard method for diagnosis of malaria. QBC can be helpful when an experienced microscopist is not available. Rapid diagnostic tests are simple, rapid, do not need expertise, interpretation of results is easy and objective and useful in routine diagnosis.

Global entrainment of transcriptional systems to periodic inputs

This paper addresses the problem of giving conditions for transcriptional systems to be globally entrained to external periodic inputs. By using contraction theory, a powerful tool from dynamical systems theory, it is shown that certain systems driven by external periodic signals have the property that all solutions converge to a fixed limit cycle. General results are proved, and the properties are verified in the specific case of some models of transcriptional systems. The basic mathematical results needed from contraction theory are proved in the paper, making it self-contained

Model Reduction in Flexible-Aircraft Dynamics with Large Rigid-Body Motion

This paper investigates the model reduction, using balanced realizations, of the unsteady aerodynamics of maneuvering flexible aircraft. The aeroelastic response of the vehicle, which may be subject to large wing deformations at trimmed flight, is captured by coupling a displacement-based, flexible-body dynamics formulation with an aerodynamic model based on the unsteady vortex lattice method. Consistent linearization of the aeroelastic problem allows the projection of the structural degrees of freedom on a few vibration modes of the unconstrained vehicle, but preserves all couplings between the rigid and elastic motions and permits the vehicle fiight dynamics to have arbitrarily-large angular velocities. The high-order aerodynamic system, which defines the mapping between the small number of generalized coordinates and unsteady aerodynamic loads, is then reduced using the balanced truncation method. Numerical studies on a representative high-altitude, long-endurance aircraft show a very substantial reduction in model size, by up to three orders of magnitude, that leads to model orders (and computational cost) similar to those in conventional frequency-based methods but with higher modeling fidelity to compute maneuver loads. Closed-loop results for the Goland wing finally demonstrate the application of this approach in the synthesis of a robust flutter suppression controller. © 2013 by Henrik Hesse and Rafael Palacios