Frequency characteristics of very fast transient currents in a 245-kV GIS

The conducted as well as the induced voltages on control cables and control circuits due to transient electromagnetic (EM) fields generated during switching operations in a gas-insulated substation (GIS) depend on the waveshape of the very fast transient overvoltages and the associated very-fast transient currents (VFTCs). The aim of this paper is to build a basis for characterizing the VFTC generated in gas-insulated switchgear and the,associated equipment during switching operations for the study of transient coupling phenomena. The peak magnitudes of VFTC and their dominant frequency content at various locations have been computed in a 245-kV GIS for different switching operations as well as substation configurations. Finally, the influence of the substation layout on the frequency spectrum, dominant frequencies, and the highest possible frequency component of the VFTC at various distances from the switch have been reported.

Mechanical processing and microstructural control in hot working of hot isostatically pressed P/M IN-100 superalloy

The hot deformation behavior of hot isostatically pressed (HIPd) P/M IN-100 superalloy has been studied in the temperature range 1000-1200 degrees C and strain rate range 0.0003-10 s(-1) using hot compression testing. A processing map has been developed on the basis of these data and using the principles of dynamic materials modelling. The map exhibited three domains: one at 1050 degrees C and 0.01 s(-1), with a peak efficiency of power dissipation of approximate to 32%, the second at 1150 degrees C and 10 s(-1), with a peak efficiency of approximate to 36% and the third at 1200 degrees C and 0.1 s(-1), with a similar efficiency. On the basis of optical and electron microscopic observations, the first domain was interpreted to represent dynamic recovery of the gamma phase, the second domain represents dynamic recrystallization (DRX) of gamma in the presence of softer gamma', while the third domain represents DRX of the gamma phase only. The gamma' phase is stable upto 1150 degrees C, gets deformed below this temperature and the chunky gamma' accumulates dislocations, which at larger strains cause cracking of this phase. At temperatures lower than 1080 degrees C and strain rates higher than 0.1 s(-1), the material exhibits flow instability, manifested in the form of adiabatic shear bands. The material may be subjected to mechanical processing without cracking or instabilities at 1200 degrees C and 0.1 s(-1), which are the conditions for DRX of the gamma phase.

Studies on glass transition and starch re-crystallization in wheat bread during staling using electrical impedance spectroscopy

Bread staling is a very complex phenomenon that is not yet completely understood. The present work explains how the electrical impedance spectroscopy technique can be utilized to investigate the effect of staling on the physicochemical properties of wheat bread during storage. An instrument based on electrical impedance spectroscopy technique is developed to study the electrical properties of wheat bread both at its crumb and crust with the help of designed multi-channel ring electrodes. Electrical impedance behavior, mainly capacitance and resistance, of wheat bread at crust and crumb during storage (up to 120 h) is investigated. The variation in capacitance showed the glass transition phenomenon at room temperature in bread crust after 96 h of storage with 18% of moisture in it. The resistance changes at bread crumb showed the starch recrystallization during staling.

Studies in Nonlinear Optical Materials: Structure of Methyl 2-(4-Ethyl-5-methyl- 2-thioxo-2,3-dihydro-l,3-thiazol- 3-yl) propionate

CIoH15NO282, Mr=245"0, orthorhombic, P21212 ~, a = 6.639 (2), b = 8.205 (2), c = 22.528(6)A, V= I227.2(6)A 3, z=4, Dm= 1.315, Dx= 1.326gem -3, MoKa, 2=0.7107A, 12= 3.63 cm -1, F(000) = 520, T= 293 K, R = 0.037 for 1115 significant reflections. The second-harmonicgeneration (SHG) efficiency of this compound is only 1/10th of the urea standard. The observed low second-order nonlinear response may be attributed to the unfavourable packing of the molecules in the crystal lattice.

Indian Ocean sea surface salinity variations in a coupled model

The variability of the sea surface salinity (SSS) in the Indian Ocean is studied using a 100-year control simulation of the Community Climate System Model (CCSM 2.0). The monsoon-driven seasonal SSS pattern in the Indian Ocean, marked by low salinity in the east and high salinity in the west, is captured by the model. The model overestimates runoff int the Bay of Bengal due to higher rainfall over the Himalayan-Tibetan regions which drain into the Bay of Bengal through Ganga-Brahmaputra rivers. The outflow of low-salinity water from the Bay of Bengal is to strong in the model. Consequently, the model Indian Ocean SSS is about 1 less than that seen in the climatology. The seasonal Indian Ocean salt balance obtained from the model is consistent with the analysis from climatological data sets. During summer, the large freshwater input into the Bay of Bengal and its redistribution decide the spatial pattern of salinity tendency. During winter, horizontal advection is the dominant contributor to the tendency term. The interannual variability of the SSS in the Indian Ocean is about five times larger than that in coupled model simulations of the North Atlantic Ocean. Regions of large interannual standard deviations are located near river mouths in the Bay of Bengal and in the eastern equatorial Indian Ocean. Both freshwater input into the ocean and advection of this anomalous flux are responsible for the generation of these anomalies. The model simulates 20 significant Indian Ocean Dipole (IOD) events and during IOD years large salinity anomalies appear in the equatorial Indian Ocean. The anomalies exist as two zonal bands: negative salinity anomalies to the north of the equator and positive to the south. The SSS anomalies for the years in which IOD is not present and for ENSO years are much weaker than during IOD years. Significant interannual SSS anomalies appear in the Indian Ocean only during IOD years.

A Monte Carlo study of crystal structure transformations

The Metropolis algorithm has been generalized to allow for the variation of shape and size of the MC cell. A calculation using different potentials illustrates how the generalized method can be used for the study of crystal structure transformations. A restricted MC integration in the nine dimensional space of the cell components also leads to the stable structure for the Lennard-Jones potential.

Effectiveness factor for zeroth-order catalytic reactions with volume change and nonuniform catalyst activity profiles

Analytical solutions are presented for the effectiveness factor of a zeroth-order reaction with volume change and nonuniform catalyst activity profile in slab, cylinder and spherical pellets. The possibility of shape normalization is considered for a variety of activity profiles and pellet shapes. When the catalyst activity at the external surface of the pellet is non-zero, shape normalization is obtained, which makes the asymptotic behavior of the effectiveness factor identical for small and large values of Thiele modulus, however, the normalization can lead to significant errors, particularly for the case of activity profiles decreasing towards the outer surface of the catalyst.

Thermal studies on melting and crystallization of polyamide fibres

Effect of heating rate on melting and crystallization of polyamide fibres has been examined using differential scanning calorimetric (DSC) technique. Peak temperature for melting (T m) and crystallization (T k) get suppressed with the increase in the heating rate which has been explained on the basis of chain orientation. Heat of melting (DeltaH m) and crystallization (DeltaH k) have been measured.DeltaH m vs. T m shows a nonlinear dependence which has been explained on the basis of entropy change. Quantitative difference inDeltaH m andDeltaH k values has been explained on the basis of orientation and degradation of the polymer.

On some design aspects of rotary vane pumps

A simple graphical design procedure is established for designing rotary vane vacuum pumps with capacities ranging from 20 litre/min to 500 litre/min, normally used in small laboratories. A new term called the idle angle is defined and its influence on the volumetric efficiency of some commercially available pumps is discussed.

Preparation, Characterisation and Thermal Properties of Hydrazinium Magnesium Sulfate

Hydrazinium magnesium sulfate, (N2H5)2Mg(SO4)2, has been prepared by dissolving magnesium powder in a solution of ammonium sulfate in hydrazine hydrate, by the reaction of ammonium magnesium sulfate with hydrazine hydrate, and by the cocrystallisation of dihydrazinium sulfate and magnesium sulfate. The product has been characterized by chemical analysis and infrared spectra. Thermal analysis of (N2H5)2Mg(SO4)2 by TG and DTA show exothermic decomposition at 302°C giving Mg(N2H4)SO4 as an intermediate and an endother-mic decomposition at 504°C producing MgSO4.

Systematic search for optical Barker codes with minimum length

A method that yields optical Barker codes of smallest known lengths for given discrimination is described.

Nature of induction of tryptophan pyrrolase in cold exposure

The activity of hepatic tryptophan pyrrolase in rats exposed to cold increased rapidly and reached a maximum of three-fold at 8 h. On continued exposure up to 48 h stress, the activity partly decreased but remained at a level higher than the initial. Withdrawal from the cold stress reversed the change. Adrenalectomy or treatment with inhibitors of protein synthesis abolished the increase in the enzyme activity during cold stress indicating a possible involvement of corticosteroids and de novo protein synthesis. Treatment with drugs known to block autonomic nervous system failed to inhibit the cold-mediated increase in enzyme activity. The results suggest that the increase in enzyme activity obtained on cold exposure is mediated by corticosteroids and not by either indoleaklylamines or autonomic nervous system. The changes in the enzyme obtained under cold stress with respect to the overshoot phenomenon, relationship to the degree of stress and reversibility on withdrawal from the stress indicate the "adaptate" nature of the response.

On the elimination of DC in reconstructed wavefronts from in-line holograms

New experimental results to demonstrate that the annoying DC in the reconstructed wavefronts from in-line holograms could be successfully eliminated are presented in this paper. The complete elimination of DC has been achieved by making proper use of a Mach-Zehnder interferometer. The results for an in-line hololens and an in-line Fourier transform hologram are discussed.

An ethnobotanical study of traditional anti-inflammatory plants used by the Lohit community of Arunachal Pradesh, India

Aim of the study: Most people especially in rural areas depend on herbal medicines to treat many diseases including inflammation-related ailments such as rheumatism, muscle swelling, cut wound, accidental bone fracture, insect bites, pains and burn by fire and hot water. The objectives of this study were: to catalog ethno-medicinal plants of Lohit community, ecological status, indigenous folk medicinal uses, morphological parts used and to determine their reported pharmacological studies. Materials and methods: The ethnobotanical information on traditional medicinal plants exclusively used for management of inflammation-related ailments by the Khampti community of Arunachal Pradesh, India was based on first-hand field survey work through semi-structured interviews. Results and conclusion: A total of 34 species in 32 genera and 22 families were encountered during the field survey. Botanical families such as Asteraceae, Euphorbiaceae, Zingiberaceae and Lamiaceae were represented by the highest numbers of species reported in this study. Thirteen plant species, namely: Bombax ceiba, Canarium strictum, Chloranthus erectus, Xanthium indicum, Lycopodium clavatum, Coleus blumei, Batrachospermum atrum, Chlorella vulgaris, Marchantia palmata, Marchantia polymorpha, Eria pannea, Sterculia villosa and Alpinia galanga are reported for the first time for the treatment of inflammation-related diseases.