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Search Results: 1 - 10 of 403200 matches for " M. Prakash "
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Hall Current Effects on Unsteady MHD Flow in a Rotating Parallel Plate Channel Bound-ed by Porous Bed on the Lower Half—Darcy Lapwood Model  [PDF]
M. Veera Krishna, Jagdish Prakash
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.54029
Abstract: We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate. The flow in the clean fluid region is governed by Navier-Stoke’s equations while in the porous bed the equations are based on Darcy-Lapwood model. The exact solutions of velocity in the clean fluid and the porous medium consist of steady state and transient state. The time required for the transient state to decay is evaluated in detail and ultimate quasi-steady state solution has been derived analytically and also its behaviour is computationally discussed with reference to different flow parameters. The shear stresses on the boundaries and the mass flux are also obtained analytically and their behaviour is computationally discussed.
Numerical Studies on Natural Convection Heat Losses from Open Cubical Cavities
M. Prakash
Journal of Engineering , 2013, DOI: 10.1155/2013/320647
Abstract: The natural convection heat losses occurring from cubical open cavities are analysed in this paper. Open cubical cavities of sides 0.1?m, 0.2?m, 0.25?m, 0.5?m, and 1?m with constant temperature back wall boundary conditions and opening ratio of 1 are studied. The Fluent CFD software is used to analyse the three-dimensional (3D) cavity models. The studies are carried out for cavities with back wall temperatures between 35°C and 100°C. The effect of cavity inclination on the convective loss is analysed for angles of 0° (cavity facing sideways), 30°, 45°, 60°, and 90° (cavity facing vertically downwards). The Rayleigh numbers involved in this study range between 4.5 × 105 and 1.5 × 109. The natural convection loss is found to increase with an increase in back wall temperature. The natural convection loss is observed to decrease with an increase in cavity inclination; the highest convective loss being at 0° and the lowest at 90° inclination. This is observed for all cavities analysed here. Nusselt number correlations involving the effect of Rayleigh number and the cavity inclination angle have been developed from the current studies. These correlations can be used for engineering applications such as electronic cooling, low- and medium-temperature solar thermal systems, passive architecture, and also refrigeration systems. 1. Introduction Buoyancy-driven heat transfer is one of the most important heat loss mechanisms from open cavities and is now widely studied due to their applications in many engineering fields such as solar thermal conversion, refrigeration, passive architecture, fire research, and electronic equipment cooling. The heat loss due to natural convection from open cavities is dependent on various factors such as shape of cavity, cavity wall boundary conditions, cavity inclination, aspect ratio, and opening ratio. Therefore in open cavities, the natural convection heat transfer analysis is complicated when compared to the heat transfer due to radiation and conduction. It is observed from the literature that experimental and numerical studies on natural convection in open cavities have been performed for different cavity shapes, namely, cubical [1–6], rectangular [7–17], and square [18–24]. Studies have also been reported on other cavity shapes used for specific applications like solar thermal receivers [25–31]. In the studies involving open cavity natural convection, two basic boundary wall conditions are observed: (a) all the walls of the open cavity were heat transfer surfaces at constant temperature [1, 2, 4, 6, 8, 9, 12, 18, 19, 21, 22,
Numerical Study of Natural Convection Heat Loss from Cylindrical Solar Cavity Receivers
M. Prakash
ISRN Renewable Energy , 2014, DOI: 10.1155/2014/104686
Abstract: The numerical study of the natural convection loss occurring from cylindrical solar cavity receivers is reported in this communication. These cavity receivers can be used with solar dish concentrators for process heat applications at medium temperature levels. Three cylindrical cavity receivers of diameter 0.2, 0.3, and 0.4?m with aspect ratio equal to one and opening ratios of 1 and 0.5 are used for the analysis. Fluent CFD software is used for the analysis of the three-dimensional (3D) receiver models. In this study the receiver tubes within the cylindrical cavity are modeled as a helical coil similar to those existing in actual systems. The flow of the working fluid within the helical coil is also modeled. The simulations are performed for fluid inlet temperatures of 150°C and 250°C and for receiver inclination angles of 0 (sideways-facing cavity), 30, 45, 60, and 90 degree (vertically downward-facing receiver). It is found that the convective loss increases with increasing mean fluid temperature and decreases with, increase in receiver inclination. The convective loss is found to increase with, opening ratio. These observations are true for all cavity receivers analysed here. A Nusselt number correlation involving Rayleigh numbers, receiver inclinations, and opening ratios is proposed for the convective loss. 1. Introduction Cavity receivers are widely used along with solar dish systems for providing industrial process heat [1, 2] generating electric power [3, 4] and for thermochemical reactions [5]. The overall efficiency of such systems is dependent on the thermal losses occurring from the cavity receiver. It is observed from the literature that the convective heat transfer constitutes a major share of the thermal losses [6–8]. The convective losses from these solar cavity receivers are found to be dependent on various parameters like receiver inclination ( ), receiver wall boundary condition, aspect ratio ( ), opening ratio ( ), and external wind. This is the reason due to which analysis of convective losses from solar cavity receivers is complicated when compared to that of heat transfer due to radiation and conduction [9, 10]. Experimental and numerical investigations on natural convection losses in cavity receivers used with solar dish concentrators have been performed on different cavity shapes. Stine and McDonald [9] have performed experimental studies on conical frustum-cylindrical cavity receivers while Kugath et al. [1] has performed field studies on a similar receiver shape at medium temperature levels. Cylindrical-shaped cavity
Probing Quark Matter In Neutron Stars
M. Prakash
Physics , 2001, DOI: 10.1016/S0375-9474(01)01399-9
Abstract: The presence of quark matter in neutron star interiors may have distinctive signatures in basic observables such as (i) masses and radii [1], (ii) surface temperatures versus age [2], (iii) spin-down rates of milli-second pulsars [3], and (iv) neutrino luminosities from future galactic core collapse supernovae [4]. I highlight recent developments in some of these areas with a view towards assessing how theory may be confirmed by $\nu-$signals from future galactic supernovae in detectors like SuperK, SNO and others under consideration, including UNO [5], and by multi-wavelength photon observations with new generation satellites such as the HST, Chandra, and XMM.
Strange Pathways for Black Hole Formation
M. Prakash
Physics , 2000, DOI: 10.1016/S0920-5632(00)00962-2
Abstract: Immediately after they are born, neutron stars are characterized by an entropy per baryon of order unity and by the presence of trapped neutrinos. If the only hadrons in the star are nucleons, these effects slightly reduce the maximum mass relative to cold, catalyzed matter. However, if stangeness-bearing hyperons, a kaon condensate, or quarks are also present, these effects result in an increase in the maximum mass of up to $\sim 0.3{\rm M}_{\odot}$ compared to that of a cold, neutrino-free star. This makes a sufficiently massive proto-neutron star metastable, so that after a delay of 10--100 seconds, the PNS collapses into a black hole. Such an event might be straightforward to observe as an abrupt cessation of neutrinos when the instability is triggered.
Quark matter and the astrophysics of neutron stars
M Prakash
Physics , 2007, DOI: 10.1088/0954-3899/34/8/S10
Abstract: Some of the means through which the possible presence of nearly deconfined quarks in neutron stars can be detected by astrophysical observations of neutron stars from their birth to old age are highlighted.
Idiopathic Reactive Hypoglycemia: Mechanisms of Onset and Remission with High Protein Low Carbohydrate Diet  [PDF]
Keshavan Prakash, Mary Kabadi, Udaya M. Kabadi
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2015, DOI: 10.4236/ojemd.2015.59015
Abstract: Objective: Idiopathic reactive hypoglycemia is defined as early postprandial hypoglycemia occurring on ingestion of high carbohydrate containing meal. Remission ensues with high protein low carbohydrate diet. This study assessed roles of insulin and glucagon in its onset and remission. Methods: Plasma glucose, insulin and glucagon were determined after an overnight fast and repeatedly until 180 minutes on ingestion of 3 meals; 100 g glucose; 100 g pure protein liquid and mixture of 50 g each at 14 days’ interval. Five adults with IRH and 6 age matched healthy volunteers participated. Results: In IRH, glucose ingestion induced prompt rise in glucose (5.1 ± 0.8 to10.5 ± 1.2 mM/L) followed later by hypoglycemia (2.6 ± 0.4 mM/L). Insulin rose from 7 ± 2 to 90 ± 18 mU/L. Glucagon rose initially (10% ± 2%) from elevated basal concentration (373 ± 57 mU/L) followed by later decline (-43% ± 12%). On protein ingestion, glucose declined followed by a restoration to basal level while both insulin and glucagon rose (28 ± 6 mU/L; 148% ± 38%, p < 0.01). However, insulin response was lower and glucagon rise was greater when compared to responses on glucose ingestion (p < 0.01). With mixed meal, glucose (8.2 ± 0.6 mM/L), insulin (65 ± 12 mU/L) and glucagon (48% ± 7%) responses were lesser than rises following glucose ingestion (p < 0.05) and hypoglycemia did not occur. Conclusion: In IRH, initial hyperglycemia on glucose ingestion may be exacerbated by paradoxical glucagon rise and hypoglycemia may be induced by increased insulin and declining glucagon responses. Resolution of hypoglycemia with high protein low carbohydrate diet may be attributed to blunting of insulin response and concurrent glucagon rise.
A Bee Optimization Algorithm for Scheduling a Job Dynamically in Grid Environment
P. Rajeswari M. Prakash
International Journal of Electronics Communication and Computer Engineering , 2011,
Abstract: Grid computing is based on large scale resources sharing in a widely connected network. Grid scheduling is defined as the process of making scheduling decisions involving allocating jobs to resources over multiple administrative domains. Scheduling is the one of the key issues in the research. Matchmaking is a key aspect in the grid environment. Matching a job with available suitable resources has to satisfy certain constraints. Resource discovery is one of the key issues for job scheduling in the grid environment. The proposed Bee optimization algorithm is to analyze Quality of Service (QoS) metrics such as service class, job type in the heterogeneous grid environment. QoS parameters play a major role in selecting grid resources and optimizing resources effectively and efficiently. The output of the proposed algorithm is compared with max-min and min-min algorithm.
Evaluation of impact of Goods and Service Tax (GST)
Dr. Prakash M. Herekar
Indian Streams Research Journal , 2012,
Abstract: The transition of closed Indian economy from a static public sector based, heavy industry dominated, import substituting to a dynamic open and export-led economy allocating resources according to market signals has necessitated systemic changes in the tax system. In an export-led open economy, the tax system should not only raise the necessary revenues to provide the social and physical infrastructure but also minimize distortions and adjust itself to the requirements of a market economy so as to ensure international competitiveness. The Finance Ministry of Government of India set up a Task Force under the chairmanship of Mr.Vijay Kelkar on the implementation of Fiscal Responsibility and Budget Management. It made recommendations to bring about a radical transformation of the Indian Tax System. It disagreed with the existing approach of the government to reduce government expenditure to achieve the fiscal consolidation.
Nature and magnitude of genetic variability and diversity studies in okra (Abelmoschus esculentus L. Moench)
K. Prakash and M. Pitchaimuthu
Electronic Journal of Plant Breeding , 2010,
Abstract: In the present investigation, an attempt has been made to evaluate the genetic variability of yield contributing characters, and the genetic diversityin forty-four genotypes of okra collected from the IIHR, Bangalore, India. Analysis of variance indicated significant differences among thegenotypes for different morphological characters. High GCV and PCV were observed for plant height, inter-nodal length, first flowering node,first fruit producing node, height of first flowering node, average fruit weight and number of seeds per fruit. On the basis of D2 analysis, the 44genotypes were grouped into twelve clusters. The cluster III was the largest with eight genotypes followed by cluster I and VIII with seven,cluster II with five, cluster XII with three while, clusters IV, V, VI, IX, X and XI included only two genotype in each. The intra-cluster distancewas maximum in cluster XII (28.14), while inter-cluster distance was maximum between cluster VI and VIII (35.57) followed by I and IX(35.31), thus being a good source for attempting hybridization. Among the 44 genotypes, IIHR-238, IIHR-241 showed maximum number offruits per plant and total yield per plant (g). The characters namely days to 50% flowering (35.62%), 100 seed weight (28.44%), number of seedsper fruit (17.23%) and average fruit weight (8.14%) directly contributed towards maximum divergence and, therefore, selection of divergentparents based on these characters is recommended for getting good hybrids or segregants in okra.
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