Parallel matrix inversion techniques

In this paper, we present techniques for inverting sparse, symmetric and positive definite matrices on parallel and distributed computers. We propose two algorithms, one for SIMD implementation and the other for MIMD implementation. These algorithms are modified versions of Gaussian elimination and they take into account the sparseness of the matrix. Our algorithms perform better than the general parallel Gaussian elimination algorithm. In order to demonstrate the usefulness of our technique, we implemented the snake problem using our sparse matrix algorithm. Our studies reveal that the proposed sparse matrix inversion algorithm significantly reduces the time taken for obtaining the solution of the snake problem. In this paper, we present the results of our experimental work

Livestock Sector in North-Eastern Region of India: An Appraisal of Performance

Although agriculture is the prime source of livelihood for a majority of rural population in the North-Eastern region (NER) of India, dependence on livestock as an alternative source of income is significant. Responding to the burgeoning demand for livestock products in a sustainable manner is a big challenge. The widening gap between the demand and supply of livestock products can be met through bringing out changes in the production structure or opening up the international trade. In this context, an analysis of performance and factors influencing development of the livestock sector in NER has been carried out. The growth of livestock sector has been found slower in the NER than at the national level. However, a significant proportion of landless labourers, small and marginal farmers have access to livestock resources and acceleration in the growth of livestock in NER offers significant opportunities for household income augmentation and employment generation. Several factors identified to influence households’ decision to rear livestock include availability of labour, occupation, caste, farm-size, availability of irrigation, and access to information sources. The study has shown that the NE states should take technical, institutional and policy initiatives for the improvement of breeds, feed availability, disease control and food safety of livestock.Livestock Production/Industries,

A new approach for vibration control in large space structures

An approach for augmenting vibration damping characteristics in space structures with large panels is presented. It is based on generation of bending moments rather than forces. The moments are generated using bimetallic strips, suitably mounted at selected stations on both sides of the large panels, under the influence of differential solar heating, giving rise to thermal gradients and stresses. The collocated angular velocity sensors are utilized in conjunction with mini-servos to regulate the control moments by flipping the bimetallic strips. A simple computation of the rate of dissipation of vibrational energy is undertaken to assess the effectiveness of the proposed approach

Electroweak Measurements of Neutron Densities in CREX and PREX at JLab, USA

Measurement of the parity-violating electron scattering asymmetry is an established technique at Jefferson Lab and provides a new opportunity to measure the weak charge distribution and hence pin down the neutron radius in nuclei in a relatively clean and model-independent way. This is because the Z boson of the weak interaction couples primarily to neutrons. We will describe the PREX and CREX experiments on ${}^{208}$Pb and ${}^{48}$Ca respectively; these are both doubly-magic nuclei whose first excited state can be discriminated by the high resolution spectrometers at JLab. The heavier lead nucleus, with a neutron excess, provides an interpretation of the neutron skin thickness in terms of properties of bulk neutron matter. For the lighter ${}^{48}$Ca nucleus, which is also rich in neutrons, microscopic nuclear theory calculations are feasible and are sensitive to poorly constrained 3-neutron forces.Comment: A contribution to the upcoming EPJA Special Volume on Nuclear Symmetry Energ

Facile preparation of agarose-chitosan hybrid materials and nanocomposite ionogels using an ionic liquid via dissolution, regeneration and sol-gel transition

We report simultaneous dissolution of agarose (AG) and chitosan (CH) in varying proportions in an ionic liquid (IL), 1-butyl-3-methylimidazolium chloride [C4mim][Cl]. Composite materials were constructed from AG-CH-IL solutions using the antisolvent methanol, and IL was recovered from the solutions. Composite materials could be uniformly decorated with silver oxide (Ag2O) nanoparticles (Ag NPs) to form nanocomposites in a single step by in situ synthesis of Ag NPs in AG-CH-IL sols, wherein the biopolymer moiety acted as both reducing and stabilizing agent. Cooling of Ag NPs-AG-CH-IL sols to room temperature resulted in high conductivity and high mechanical strength nanocomposite ionogels. The structure, stability and physiochemical properties of composite materials and nanocomposites were characterized by several analytical techniques, such as Fourier transform infrared (FTIR), CD spectroscopy, differential scanning colorimetric (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), and scanning electron micrography (SEM). The result shows that composite materials have good thermal and conformational stability, compatibility and strong hydrogen bonding interactions between AG-CH complexes. Decoration of Ag NPs in composites and ionogels was confirmed by UV-Vis spectroscopy, SEM, TEM, EDAX and XRD. The mechanical and conducting properties of composite ionogels have been characterized by rheology and current-voltage measurements. Since Ag NPs show good antimicrobial activity, Ag NPs -AG-CH composite materials have the potential to be used in biotechnology and biomedical applications whereas nanocomposite ionogels will be suitable as precursors for applications such as quasi-solid dye sensitized solar cells, actuators, sensors or electrochromic displays

Classical Langevin dynamics of a charged particle moving on a sphere and diamagnetism: A surprise

It is generally known that the orbital diamagnetism of a classical system of charged particles in thermal equilibrium is identically zero -- the Bohr-van Leeuwen theorem. Physically, this null result derives from the exact cancellation of the orbital diamagnetic moment associated with the complete cyclotron orbits of the charged particles by the paramagnetic moment subtended by the incomplete orbits skipping the boundary in the opposite sense. Motivated by this crucial, but subtle role of the boundary, we have simulated here the case of a finite but \emph{unbounded} system, namely that of a charged particle moving on the surface of a sphere in the presence of an externally applied uniform magnetic field. Following a real space-time approach based on the classical Langevin equation, we have computed the orbital magnetic moment which now indeed turns out to be non-zero, and has the diamagnetic sign. To the best of our knowledge, this is the first report of the possibility of finite classical diamagnetism in principle, and it is due to the avoided cancellation.Comment: Accepted for publication in EP

Inflation in a two 3-form fields scenario

A setting constituted by $\mathbb{N}$ 3-form fields, without any direct interaction between them, minimally coupled to gravity, is introduced in this paper as a framework to study the early evolution of the universe. We focus particularly on the two 3-forms case. An inflationary scenario is found, emerging from the coupling to gravity. More concretely, the fields coupled in this manner exhibit a complex interaction, mediated by the time derivative of the Hubble parameter. Our investigation is supported by means of a suitable choice of potentials, employing numerical methods and analytical approximations. In more detail, the oscillations on the small field limit become correlated, and one field is intertwined with the other. In this type of solution, a varying sound speed is present, together with the generation of isocurvature perturbations. The mentioned features allow to consider an interesting model, to test against observation. It is subsequently shown how our results are consistent with current CMB data (viz.Planck and BICEP2).Comment: Version accepted in JCAP. 22 pages, 12 figures, new refs adde

An analytical stability theory for Faraday waves and the observation of the harmonic surface response

We present an analytical stability theory for the onset of the Faraday instability, applying over a wide frequency range between shallow water gravity and deep water capillary waves. For sufficiently thin fluid layers the surface is predicted to occur in harmonic rather than subharmonic resonance with the forcing. An experimental confirmation of this result is given. PACS: 47.20.Ma, 47.20.Gv, 47.15.CbComment: 10 pages (LaTeX-file), 3 figures (Postscript) Submitted for publicatio