SIMD Optimization of Linear Expressions for Programmable Graphics Hardware

The increased programmability of graphics hardware allows efficient graphical processing unit (GPU) implementations of a wide range of general computations on commodity PCs. An important factor in such implementations is how to fully exploit the SIMD computing capacities offered by modern graphics processors. Linear expressions in the form of , where A is a matrix, and and are vectors, constitute one of the most basic operations in many scientific computations. In this paper, we propose a SIMD code optimization technique that enables efficient shader codes to be generated for evaluating linear expressions. It is shown that performance can be improved considerably by efficiently packing arithmetic operations into four‐wide SIMD instructions through reordering of the operations in linear expressions. We demonstrate that the presented technique can be used effectively for programming both vertex and pixel shaders for a variety of mathematical applications, including integrating differential equations and solving a sparse linear system of equations using iterative methods.     

Predicting Spam Messages Using Back Propagation Neural Network

Wireless Personal Communications - With the increase in popularity of smartphones, text-based communication has also gained popularity. Availability of messaging services at low cost has resulted...     

Enhancing the Performance of Video Streaming in Wireless Mesh Networks

Multihop wireless mesh networks (WMNs) provide ubiquitous wireless access in a large area with less dependence on wired networks. However, some emerging applications with high bandwidth requirement and delay and loss constraints, such as video streaming, suffer poor performance in WMNs, since high compression rates and/or high packet loss rates deteriorate the video quality. In this paper, we propose a novel mechanism composed of (1) a network route selection scheme which provides paths for multiple video streams with the least interference, called Minimum Interference Route Selection (MIROSE) and (2) an optimization algorithm that determines the compression rates depending on the network condition, called Network State Dependent Video Compression Rate (NSDVCR) algorithm. Simulation results of the proposed mechanisms show the significant improvement of the video quality measured with a popular metric, Peak-Signal-to-Noise Ratio (PSNR), compared with standard routing and default compression rates.     

Thermodynamic study of the Np-Zr system

A thermodynamic model of the Np-Zr system is developed using the CALPHAD method, and a review of previous work performed on this system is presented here. In general, results obtained are in good agreement with those proposed from experimental observations. It is found that the nature of reactivity of Np with Zr, is different from that of U and Pu: an expected elevation of melting point of Np-Zr alloys was not seen and a miscibility gap existed between the high-temperature bcc phases of Np and Zr. Formation enthalpy of the bcc phase obtained from the model is compared with results from KKR-ASA-CPA calculations. Lattice stabilities of various phases in the system are compared to values obtained from first-principles LDA and GGA calculations. The δ-NpZr₂ phase is modeled as a non-stoichiometric phase with a C32 structure, similar to what has been determined for the δ-phase in the U-Zr system. This phase is analogous to ω-phase in pure Zr, which is stabilized at high pressures. Two different possibilities for stability of the δ and ω phases have been proposed in the present work. Finally, calculated changes in enthalpy versus temperature are plotted for two alloys to guide future experimental work in resolving important issues in this system.     

Novel high performance fibres

The need for high performance materials for aerospace and other structural engineering applications has led to the development of carbon fibres. At IIT Delhi, an attempt is being made to develop acrylic precursor fibres for manufacturing carbon fibres indigenously. The present study deals with the structural regulation of acrylic precursors during thermo-oxidative stabilization and subsequent carbonization. A new microporous acrylic fibre-acrysorb has also been developed which has high water imbibition and moisture sorption properties. Production of X-ray opaque and antistatic polyester fibres has also been high-lighted.     

High resolutionV-I characteristics measurements on highT c superconductors

V-I characteristics of sintered superconducting pellets of YBa₂Cu₃O_7−δ was measured with a resolution one order of magnitude better than the usual dc techniques employing nanovoltmeters. For this purpose software-based lock-in-amplifier technique was developed and used. A square-wave excitation current was used. The voltage signal was digitized into a time series and Fourier-analysed on a computer in this technique. Our results show a very small frequency-dependent resistance in some samples which are nominally superconducting. These results help in checking the material quality and defining the critical current densities better.     

The genetics of Parkinson''s disease and parkinsonian syndromes

General anaesthesia with 80% CO2/20% O2 and 5% halothane in O2 (mask induction) was compared for castration of 3-4 week-old piglets. One group was castrated without anaesthesia. Of the noncastrated control groups one had CO2- and one halothane anaesthesia, one breathed room air through the induction system, and one was held in castration position. The behaviour to induction and castration was assessed, and the cortisol-, ACTH- and beta-endorphin plasma concentrations were determined to quantify the stress elicited by anaesthesia, castration and handling. Violent struggling and vocalization were elicited by CO2 and positioning into the mask induction system while breathing room air; halothane induction was quiet. CO2 induced profound surgical anaesthesia; whereas under halothane anaesthesia some animals exhibited still a slight reaction to castration. Recovery was fast, smooth and quite. Permanent violent struggling and vocalization were elicited by castration without anaesthesia. Plasma cortisol was not a sensitive tool to judge castration stress. The high ACTH and beta-endorphin plasma concentrations elicited by CO2 anaesthesia confirm our clinical experience. General anaesthesia is fast and safely induced with CO2 in piglets and castration can be performed without any reaction, but with CO2 anaesthesia the stress is not reduced.     

Aliphatic-aromatic copolyesters: synthesis and crystallization studies

A melt condensation technique has been employed for the synthesis of aliphatic-aromatic copolyesters using bisphenol-A, resorcinol, hydroquinone and 4,4′-dihydroxydiphenyl sulphone. The incorporation of bisphenols was ascertained by chemical composition using infra-red and nuclear magnetic resonance spectra. The effect of the catalyst and stirring during condensation has been studied. The dependence of thermal properties and crystallization behaviour on copolyester composition has been considered. The results are compared with those obtained by wide-angle X-ray diffraction and density studies.