Development of a creep data base management system for engineering materials

A fully menu driven creep data base management system has been developed for various high temperature materials using the client /server (C/S) architecture with Sybase system. 10 as backend and power builder 4.0 as an inter-face. The relational data base constitutes of various classes of materials, their heat treatment, prior history and the related creep properties at different test condit-ions, in addition to the source process route and chemical composition details.Top-down approach has been adopted in designing the entity-relationship (E-R) model. The creep data is organized into the third normal form, and the entire system is divided into manageable modules. Coding for the system is done using Transact-SQL for data defin- ition, manipulation and control operations, and power script language for application development. This article briefly outlines the formulation of data base design, and the implemented E-R model, in addition , to the prese-ntation of various screen formats used for data entry and retrieval modules

Study of Variation in Upper Air Density Over India

The paper presents the seasonal variations and distribution of atmospheric density in the upper air over Indian region. The study reveals the density gradient has a down slope from North to South during winter and South to North, upto 200 mb level in summer. At 850 mb level the isopyenic lines forms a shallow through over East coast and at 700 mb level Bombay-Poona region while over the rest of the country the isopyenics show no special features. At 500 mb level three is a well marked trough of density over North Western India. Above 200 mb level an altogether different picture throughout the year is noticed

A Computational Teddqae for Heat W a r h e to a Fast Movhg Hl(lf 80urce

The heat transfer in the two phase region in the study of melting and solidification of a surface layer by a moving heat source is studied.The transient problem is formulated using the enthalpy and temperature model and solved in an oblate spheroidal co-ordinate system using animplicit modified upwinding scheme in terms of non-dimensional nodal enthalpy and temperature. It is observed that the temperature gradient which controls the solidification rate, increases to a maximum initiallyand then decreases to zero. It is found that the solid-liquid interface velocity which is zero initially very quickly reaches to the velocity ofthe heat source, though the gradient ahead of the interface relaxes much more slowly

A NEW SPEECH ENHANCEMENT TECHNIQUE USING PERCEPTUAL CONSTRAINED SPECTRAL WEIGHTING FACTORS

This paper deals with musical noise result from perceptual speech enhancement type algorithms and especially wiener filtering. Although perceptual speech enhancement methods perform better than the non perceptual methods, most of them still return annoying residual musical noise. This is due to the fact that if only noise above the noise masking threshold is filtered then noise below the noise masking threshold can become audible if its maskers are filtered. It can affect the performance of perceptual speech enhancement method that process audible noise only. In order to overcome this drawback here proposed a new speech enhancement technique. It aims to improve the quality of the enhanced speech signal provided by perceptual wiener filtering by controlling the latter via a second filter regarded as a psychoacoustically motivated weighting factor. The simulation results shows that the performance is improved compared to other perceptual speech enhancement method

Carbon-13 enrichment by IR laser chemistry of CHF<SUB>3</SUB>-Cl<SUB>2</SUB>

IR laser chemistry of CHF3 is investigated in both neat form and in the presence of Cl2 for carbon-13 enrichment. Infrared multiple-photon dissociation of CHF3 is an order of magnitude more efficient in the scavenged system compared to the neat case. The photolysis of CHF3/Cl2 mixture results in two products, viz., CF2Cl2 and C2F4Cl2 but with different enrichment factors. The parametric studies show that C2F4Cl2 arises due to MPD of CF2Cl2 in secondary photolysis

Millimetric Wave Seeker for Third Generation Antitank Guided Missiles

For the third generation antitank guided missiles (ATGMs) with fire-and-forget and top attack capabilities, a noncoherent millimetric wave (MMW) active radar seeker has been configured with all weather capabilities. To meet the stringent dimensional and weight constraints and beamwidth requirements of ATGM, a W-band system has been designed with trans-twist antenna with a compact comparator. The paper covers the system description and critical design issues, and presents the performance results achieved so far. Areas for improvements, especially for achieving a higher range, have also been pointed out

Selective IR laser chemistry of CDF<SUB>3</SUB> in natural fluoroform

Selective decomposition of CDF3 at natural abundance level (&#8776;150ppm) in fluoroform has been achieved by infra-red multiple-photon excitation at moderate substrate pressure using 100 ns FWHM CO2 laser pulses. Effects of energy fluence, number of laser pulses, buffer gas pressure and substrate pressure on decomposition yield and bulk selectivity are reported and discussed

Transient isomerisation and inverse electronic relaxation of infrared multiple-photon excited Pentafluoropyridine

Pentafluoropyridine (PFP) undergoes fast structural isomerisation to fulvenes when irradiated with 9R(16) CO2 laser line in the fluence range 0.5-1.5 J/cm2. The unstable fulvenes slowly decay back to PFP in ms time scale. No detectable permanent dissociation of PFP was observed in the above low fluence experiments. However, by using focused CO2 laser beam for the irradiation of PFP, an emission of light in the visible/near-UV was observed. The time evolution of the luminescence reveals three peaks at 390, 460 and 500 nm on a broad background emission of 300-680 nm. These bands are assigned to the fluorescence of PFP via inverse electronic relaxation (IER) and C2 Swan bands. On prolonged irradiation of PFP in focused condition a small extent of permanent dissociation was observed with the major products as C2F4, a sooty yellow deposit and another compound presumed to be Dewar PFP

Seaweed resources of the Tuticorin-Tiruchendur coast, Tamil Nadu, India

The southern coast of Tamil Nadu (Mandapam to Kanyakumari) supports luxuriant growth of economic seaweeds. The entire indigenous phycocoUoid industry of the country gets the raw material from this region and during the last two decades, due to indiscriminate harvesting, there has been over-exploitation of the resource. The present paper deals with survey conducted in the first sector from Tuticorin to Tiruchendur during December 1986—March 1987. In this study 58 species of marine algae were recorded of which 7 belong to Chlorophyta, 12 to Phaeophyta and 39 to Rhodophyta besides 3 species of seagrasses namely Cymodocea seiriilata, Halophila ovalis and //. ovata within 650 sq. km area surveyed. The total standing crop of the seaweeds was estimated at 9,100 tonnes (wt.). The estimates for the dominant species are Dictyota maxima 530 t, Sargassum tenerrium 640 t, D. bartayresiana 8601, Selieria rebusta 2,0901 and Hypnea valemiae 2,4301. The seaweed potential for commercial exploitation has been briefly discussed