An effective Nuclear Model: from Nuclear Matter to Finite Nuclei

The momentum and density dependence of mean fields in symmetric and asymmetric nuclear matter are analysed using the simple density dependent finite range effective interaction containing a single Gaussian term alongwith the zero-range terms. Within the formalism developed, it is possible to reproduce the various diverging predictions on the momentum and density dependence of isovector part of the mean field in asymmetric matter. The finite nucleus calculation is formulated for the simple Gaussian interaction in the framework of quasilocal density functional theory. The prediction of energies and charge radii of the interaction for the spherical nuclei compares well with the results of other effective theories.Comment: 10 pages, 3 figures, 2 tables, To appear in the Proceedings of the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), May 27-June 1, 2012, San Antonio, Texas, US

Wave scattering by a partial flexible porous barrier in the presence of a step-type bottom topography

A semi-analytic model is presented for oblique wave scattering by a bottom-standing or surface-piercing flexible porous barrier in water of finite depth with a step-type bottom topography. The physical problem is solved using the methods of least-squares and multi-mode approximation associated with the modified mild-slope equation. Effects on the wave scattering due to bed profile, structural rigidity, compressive force, angle of incidence, barrier length, porosity, and height of the step are examined. The study reveals that under some special conditions, nearly zero/full reflection may occur in the case of wave scattering by a partial flexible porous barrier in the presence of an undulated bottom topography. Further, the study predicts that the Bragg resonance may not occur in the case of wave scattering by a topography of sinusoidal profile. The present study provides insights to help understand how waves are transformed in a marine environment with/without flexible porous barriers in the presence of a bottom topography. The concept and methodology can be generalized to analyze problems of similar nature arising in ocean engineering.postprin

On Spatial Consensus Formation: Is the Sznajd Model Different from a Voter Model?

In this paper, we investigate the so-called ``Sznajd Model'' (SM) in one dimension, which is a simple cellular automata approach to consensus formation among two opposite opinions (described by spin up or down). To elucidate the SM dynamics, we first provide results of computer simulations for the spatio-temporal evolution of the opinion distribution $L(t)$, the evolution of magnetization $m(t)$, the distribution of decision times $P(\tau)$ and relaxation times $P(\mu)$. In the main part of the paper, it is shown that the SM can be completely reformulated in terms of a linear VM, where the transition rates towards a given opinion are directly proportional to frequency of the respective opinion of the second-nearest neighbors (no matter what the nearest neighbors are). So, the SM dynamics can be reduced to one rule, ``Just follow your second-nearest neighbor''. The equivalence is demonstrated by extensive computer simulations that show the same behavior between SM and VM in terms of $L(t)$, $m(t)$, $P(\tau)$, $P(\mu)$, and the final attractor statistics. The reformulation of the SM in terms of a VM involves a new parameter $\sigma$, to bias between anti- and ferromagnetic decisions in the case of frustration. We show that $\sigma$ plays a crucial role in explaining the phase transition observed in SM. We further explore the role of synchronous versus asynchronous update rules on the intermediate dynamics and the final attractors. Compared to the original SM, we find three additional attractors, two of them related to an asymmetric coexistence between the opposite opinions.Comment: 22 pages, 20 figures. For related publications see http://www.ais.fraunhofer.de/~fran

Unusual ocean-atmosphere conditions in the tropical Indian Ocean during 1994

The southeastern tropical Indian Ocean (SETIO) was characterized by unusually cold sea surface temperature (SST) and strong northwestward alongshore surface winds during 1994. Using multi-source data sets including ocean model simulation, two key processes are identified for the SETIO cooling. Entrainment cooling produced most of the negative SST anomaly near the coast whereas evaporative cooling dominated the process away from the coast. Convection was anomalously suppressed over SETIO and the divergence of moist air from the region helped the local evaporative process. This also led to anomalous moisture transports that explain the enhanced convection over the central equatorial Indian Ocean, India and East Asia. The positive feedback between the enhanced and suppressed convection regions in turn helped maintain the surface wind anomalies. These evidences clearly indicate the existence of an ocean-atmosphere coupled phenomenon in the Indian Ocean during 1994

Trace element analysis of fly ash samples by EDXRF technique

Trace element analysis of some fly ash samples and soil samples have been carried out by Energy Dispersive X-Ray Fluorescence technique. Fourteen elements namely K, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Sr and Pb have been quantified in the fly ash samples by this technique. It was found that there is no huge concentration difference between the fly ash and soil samples as a result of which fly ash can be used as soil manure without any adverse impact on the plants.Trace element analysis of fly ash samples by EDXRF technique T R Rautray1*, B Behera1, T Badapanda1, V Vijayan2 and S Panigrahi1 1Department of Physics, National Institute of Technology, Rourkela-769 008, Orissa, India 2Department of Physics, Valliammai Engineering College, SRM Nagar, Chennai-603 203, Tamil Nadu, India E-mail : [email protected] of Physics, National Institute of Technology, Rourkela-769 008, Orissa, India 2Department of Physics, Valliammai Engineering College, SRM Nagar, Chennai-603 203, Tamil Nadu, Indi

Space-time codes for wireless communication

With an increasing demand for high data rate, there has been a lot of research in the field of wireless communication. This paper deals with the fundamentals of space-time coding for wireless communication systems. A well-known technique known as Space]Time Coding has been adopted in the systems using multiple antennas for high speed and reliable communication. The basic idea of space-time coding deals with the designing of two-dimensional signal matrix that is to be transmitted over an interval of time from a number of transmitting antennas. High data rate and improved bit error performance can be achieved by exploiting diversity in the spatial dimensions by designing appropriate signal structure. Space-Time Block Coding is a MIMO transmit strategy which exploits transmit diversity and high reliability. We analyze the basic design structure of the space- time codes and summarize their relative performances