Showing papers by "Jadavpur University published in 1990"

A Note on an Inventory Model with Inventory-level-dependent Demand Rate

Abstract: This model discusses an infinite time-horizon deterministic inventory model without shortages, where the demand rate at any instant depends on the on-hand inventory (stock level) at that instant down to a certain stock level and then it becomes constant for the remaining period of the cycle. The decision rule for finding the optimal order quantity is also given, and three numerical examples are presented to illustrate the model developed.

String Cosmology in Bianchi I Space-time

Abstract: Some cosmological solutions of massive strings are obtained in Bianchi I space-time following the techniques used by Letelier and Stachel. A class of solutions corresponds to string cosmology associated with/without a magnetic field and the other class consists of pure massive strings, obeying the Takabayashi equation of stateρ=(1+W)λ.

Petro-tectonic Imprints in the Sapphirine Granulites from Anantagiri, Eastern Ghats Mobile Belt, India

Abstract: Sapphirine granulite occurring as lenses in charnockite at Anantagiri, Eastern Ghat, India, displays an array of minerals which developed under different P-T-X conditions. Reaction textures in conjunction with mineral chemical data attest to several Fe-Mg continuous reactions, such as spinel+rutile+quartz+MgFe −1 =sapphirine+ilmenite cordierite=sapphirine+quartz+MgFe −1 sapphirine+quartz=orthopyroxene+sillimanite+MgFe −1 orthopyroxene+sapphirine+quartz=garnet+MgFe −1 orthopyroxene+sillimanite=garnet+quartz+MgFe −1 orthopyroxene+sillimanite+quartz+MgFe −1 =cordierite. Calculated positions of the reaction curves in P-T space, together with discrete P-T points obtained through geothermobarometry in sapphirine granulite and the closely associated charnockite and mafic granulite, define an anticlockwise P-T trajectory. This comprises a high-T/P prograde metamorphic path which culminated in a pressure regime of 8.3 kb above 950°C, a nearly isobaric cooling (IBC) path (from 950°C, 8.3 kb, to 675°C, 7.5kb) and a terminal decompressive path (from 7.5 to 4.5 kb). Spinel, quartz, high-Mg cordierite, and sapphirine were stabilized during the prograde high-T/P metamorphism, followed by the development of orthopyroxene, sillimanite, and garnet during the IBC. Retrograde low-Mg cordierite appeared as a consequence of decompression in the sapphirine granulite. Deformational structures, reported from the Eastern Ghat granulites, and the available geochronological data indicate that prograde metamorphism could have occurred at 3000±100 and 2500±100 Ma during a compressive orogeny that was associated with high heat influx through mafic magmatism. IBC ensued from P max and was thus a direct consequence of prograde metamorphism. However, in the absence of sufficient study on the spatial variation in P-T paths and the strain histories in relation to time, the linkage between IBC and isothermal decompression (ITD) has remained obscure. A prolonged IBC followed by ITD could be the consequence of one extensional mechanism which had an insufficient acceleration at the early stage, or ITD separately could be caused by an unrelated extensional tectonism. The complex cooled nearly isobarically from 2500 Ma. It suffered rapid decompression accompanied by anorthosite and alkaline magmatism at ~1400-1000 Ma.

Anti-inflammatory and related actions of Syzygium cuminii seed extract

Abstract: The chloroform fraction of Syzygium cuminii seeds was found to cause significant inhibition of carrageenin, kaolin and other mediator-induced oedema. The extract inhibited exudation of protein, leakage of dye in peritoneal inflammation and migration of leucocytes. The extract also caused inhibition of grannloma formation, experimental arthritis and also turpentine-induced joint oedema. Significant anti-pyretic action of the extract was also observed against yeast-induced pyrexia. These observations established the anti-inflammatory effect of S. cuminii seed extract in exudative, proliferative and chronic stages of inflammation along with an anti-pyretic action.

An orthopyroxene–biotite geothermometer and its application in crustal granulites and mantle-derived rocks

Abstract: Using the experimental data on Fe-Mg exchange between orthopyroxene and biotite of Fonarev & Konilov (1986), an orthopyroxene–biotite geothermometer is developed. The thermometer is corrected for mixing of Ti and Al in octahedral sites in biotite and also for non-ideal mixing of Fe and Mg in orthopyroxene. The thermometer is applied to several amphibolite–granulite transition facies and granulite facies rocks and also to mantle xenoliths. It yields consistent results in rocks of widely varying bulk composition, and highly magnesian mantle xenoliths. This thermometer removes the difficulty of estimating temperature in garnet-free rocks in high-grade terrains and also provides independent estimates of temperature in garnet-bearing assemblages.

Compositional characteristics of glauconitic alterations of K-feldspar from India and their implications

Abstract: Chemical characteristics of glauconite and ferric illite derived from alteration of K-feldspar in three Proterozoic formations of India are studied. The phases show widely varying octahedral and tetrahedral cation contents, but K-content is nearly constant. Co-existence of glauconite and ferric illite is interpreted as due to influx of fresh water in a marine-dominated sequence. A continuum in composition between illitic and glauconitic minerals at high alkali content is established. No correlation between composition of glauconite and environment of deposition or degree of diagenesis is deduced. Ferric illite in fluvial environment contains less Mg than that in a marine-dominated one. Direct pseudomorphism of K-feldspars by glauconite and ferric illite in their respective chemical en ironments controlled largely by the availability of Fe and Mg is indicated in this study. Chemical characteristics of glauconite and ferric illite in an environment with high aK+ induced by dissolution of K-feldspar are markedly different from those described earlier.

Singhbhum Shear Zone: Structural transition and a kinematic model

Abstract: The northern fold belt away from the Singhbhum Shear Zone displays a set of folds on bedding The folds are sub-horizontal with E-W to ESE striking steep axial surfaces In contrast, the folds in the Singhbhum Shear Zone developed on a mylonitic foliation and have a reclined geometry with northerly trending axes There is a transitional zone between the two, where the bedding and the cleavage have become parallel by isoclinal folding and two sets of reclined folds have developed by deforming the bedding—parallel cleavage Southward from the northern fold belt the intensity of deformation increases, the folds become tightened and overturned towards the south while the fold hinges are rotated from the sub-horizontal position to a down-dip attitude Recognition of the transitional zone and the identification of the overlapping character of deformation in the shear zone and the northern belt enable the formulation of a bulk kinematic model for the area as a whole

Photo-induced electron transfer in surfactant solutions containing thionine dye

Abstract: The mechanism of photovoltage generation in the micellar solution of nonionic surfactants incorporating thionine dye involves charge-transfer (CT) or electron donor acceptor (EDA) interaction; the dye acts as the electron acceptor and the surfactants act as the electron donors. This is well corroborated by the spectral studies of the systems. The thermodynamic and spectral properties of the complexes are presented. The photovoltage generation, the spectral shifts due to complexation, and the thermodynamic properties of the complexes are found to be well correlated.

SEM Studies of the Surface and Fracture Morphology of Pineapple Leaf Fibers

Abstract: The structural features and fracture morphology of raw and chemically treated pineapple leaf fiber have been studied using scanning electron microscopy. Pineapple leaf has a multicellular structure, and alkali treatment clearly reveals the ultimate fibers. Surface morphology progressively changes with gradual removal of noncehulosic constituents like lignin and hemicellulose. Fracture morphology shows that there is a uniform sharing of the load in the ultimate fibers of raw pineapple leaf, whereas treated leaf shows irregular fractures characterized by the slippage of individual ultimate fibers.

Optical Properties and Nature of Coordination of Cu+ Ions in Calcium Metaphosphate Glass

Abstract: Absorption, emission, and excitation spectra of copper(I) ions in calcium metaphosphate glass are investigated. Analysis of the absorption spectrum in the light of ligand field theory reveals that the oxygen coordination surrounding the ion in glass is grossly a trigonally distorted octahedron. A chemical model for the copper(I) ion site in glass is proposed and the mode of distortions that brings about strong trigonal fields at the central ion is discussed. The lowest triplet (3Eg) in the system is identified from emission and lifetime measurements. The observed duality of the triplet emission and its excitation dependence are ascribed to the existence of two relatively predominant slightly different copper(I) sites under the same gross coordination field structure of the glass. Es werden Absorption-, Emissions- und Anregungsspektren von Kupfer(I)-Ionen in Kalzium-metaphosphatglas untersucht. Eine Analyse des Absorptionsspektrums mit der Ligandenfeld-theorie zeigt, das die Sauerstoff-Koordination um das Ion im Glas grob ein trigonal verzerrtes Oktaeder ist. Es wird ein chemisches Modell fur den Kupfer(I)-Ionenplatz im Glas vorgeschlagen und die Verzerrungsmode, die die starken trigonalen Felder am Zentralion hervorruft, diskutiert. Das niedrigste Triplett (3Eg) im System wird aus Emission- und Lebensdauermessungen identifiziert. Die beobachtete Dualitat der Triplettemission und seine Anregungsabhangigkeit werden der Existenz von zwei relativ vorherrschenden schwach unterschiedlichen Kupfer(I)-Platzen unter derselben gesamten Koordinationsfeldstruktur des Glases zugeordnet.

Tide versus storm in Epeiric coastal deposition: Two Proterozoic sequences, India

Abstract: The relative importance of tides and storms in coastal sedimentation in ancient epeiric seas is frequently problematical. Here we appraise the depositional regimes in two Proterozoic Vindhyan formations in India with the aim of elucidating the records of each of these processes. The respective products of the two processes are not easily distinguished as both of them entail repeated fluctuations in water level and depositional energy. Two orders of fluctuation are recognized in both formations. The nature and scale of these two orders of fluctuation along with high-resolution facies analysis make the distinction between the respective products of the two processes possible. Many of the features so long counted as characteristics of tidal rhythms, in the studied formations, exclusively or frequently manifest waxing and waning of storms or fairweather–storm cyclicity. This study highlights the need for reevaluation of ancient coastal sequences in epeiric setting.

Increased time-constant dual-input integrators

Abstract: Two active-RC integrators are proposed. They provide ideal integration function realization with dual-input capability, the use of a grounded capacitor, and an increase in time-constant ( tau /sub 0/) over its nominal value ( tau ), which is made possible by a single resistor-controlled multiplier. Sensitivity characteristics of the proposed networks are considered. The integrators have been built in the laboratory with mu A 741 amplifiers and using tau =0.4 mu F*10 k Omega and n=1-10. With square-wave testing under continuous tuning, the expected triangular wave generation was observed at the output (V/sub 0/). The variation of the slope lambda =V/sub 0//t of the rising and falling edges of the output triangular wave for different settings of n has been measured; the results are shown. The differential integration function for each network has been tested by feeding two square-wave inputs of the same magnitude (3.6 V), but different periods; the integrator responses are given. >

A simple analog divider having independent control of sensitivity and design conditions

Abstract: A simple, low-cost analog divider circuit using the voltage-variable resistance (VVR) property of a field-effect transistor (FET) is presented. The circuit is useful in signal processing for instrumentation systems. An example application is in linearizing a transducer. Experimental studies of the divider circuit are discussed. A simultaneous multiplier-divider circuit derived from the presented scheme is also discussed. >

Viscous fluid in a Kaluza-Klein metric

Abstract: Exact solutions are obtained in a five-dimensional space-time with an energy-momentum tensor containing a viscous fluid, assuming either an equation of state or a special form for the viscous term in line with the assumption of Belinskii and Khalatnikov (1977). The solutions are, in fact, generalizations of an earlier work by Gron for a perfect fluid in the 5D rest-mass varying theory of gravity proposed recently by Wesson. It is found that dimensional reduction of the extra space takes place in some of the cases such that the 5-dimensional universe naturally evolves into an effective 4-dimensional one. A huge amount of entropy can be produced following this shrinkage of extra-dimension which may account for the very large value of entropy per baryon observed in our 4D world. Moreover, the observed constancy of the rest-mass in the present era is also interpreted.

A high-quality dual-input differentiator

Abstract: A dual-input ideal differentiator network design with a single resistor-controlled time constant and high-gain operational amplifier (OA) devices is described. At high frequencies, the network becomes functionally nonideal and its quality factor (Q) degrades because of the frequency-dependent gain of the OA. A suitable Q-compensation design that yields a 1: mod A mod /sup 2/ order of Q improvement at higher frequencies is proposed. The network exhibits high-frequency deemphasis characteristics due to the OA-poles which would suppress the high-frequency noise components. >

Thermelectric power in ultrathin films of A 3 II B 2 V semiconductors in the presence of a quantizing magnetic field

Abstract: An attempt is made to study theoretically the thermoelectric power in ultrathin films ofA 3 II B 2 V semiconductors in the presence of a quantizing magnetic field by formulating a new magneto-dispersion law, within the framework ofk · p formalism incorporating the anisotropies in the band parameters It is found, taking ultrathin films ofn-Cd3P2 as an example, that the same power decreases with increasing surface electron concentration and changes in an oscillatory manner with film thickness and quantizing magnetic field In addition, the well-known results for parabolic energy bands have also obtained from our expressions as special cases