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Search Results: 1 - 10 of 3517 matches for " Goutam Ghosh "
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Reversible Digital Image Watermarking Scheme Using Bit Replacement and Majority Algorithm Technique  [PDF]
Koushik Pal, Goutam Ghosh, Mahua Bhattacharya
Journal of Intelligent Learning Systems and Applications (JILSA) , 2012, DOI: 10.4236/jilsa.2012.43020
Abstract: The current paper presents a new digital watermarking method through bit replacement technology, which stores mul-tiple copies of the same data that is to be hidden in a scrambled form in the cover image. In this paper an indigenous approach is described for recovering the data from the damaged copies of the data under attack by applying a majority algorithm to find the closest twin of the embedded information. A new type of non-oblivious detection method is also proposed. The improvement in performance is supported through experimental results which show much enhancement in the visual and statistical invisibility of hidden data.
Wear Behaviour of Al-SiCp Metal Matrix Composites and Optimization Using Taguchi Method and Grey Relational Analysis  [PDF]
Shouvik Ghosh, Prasanta Sahoo, Goutam Sutradhar
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.1111115
Abstract: Aluminium metal matrix composite is a relatively new material that has proved its position in automobile, aerospace and other engineering design applications due to its wear resistance and substantial hardness. Need for improved tribological performance has led to the design and selection of newer variants of the composite. The present investigation deals with the study of wear behaviour of Al-SiCp metal matrix composite for varying reinforcement content, applied load, sliding speed and time. Aluminium metal matrix composites reinforced with SiC particles are prepared by liquid metallurgy route using LM6 aluminium alloy and silicon carbide particles (size ~ 37 μm) by varying the weight fraction of SiC in the range of 5% - 10%. The material is synthesized by stir casting process in an electric melting furnace. The materials are then subjected to wear testing in a multitribotester using block on roller configuration. A plan of experiments based on L27 Taguchi orthogonal array is used to acquire the wear data in a controlled way. An analysis of variance is employed to investigate the influence of four controlling parameters, viz., SiC content, normal load, sliding speed and sliding time on dry sliding wear of the composites. It is observed that SiC content, sliding speed and normal load significantly affect the dry sliding wear. The optimal combination of the four controlling parameters is also obtained for minimum wear. The microstructure study of worn surfaces indicates nature of wear to be mostly abrasive.
Functional responses of Laccotrephes griseus (Hemiptera: Nepidae) against Culex quinquefasciatus (Diptera: Culicidae) in laboratory bioassay
Anupam Ghosh & Goutam Chandra
Journal of Vector Borne Diseases , 2011,
Abstract: Background and objectives: In integrated vector management programmes, major emphasis is given on theapplication of biocontrol agents. In the present study, the hemipteran water bug, Laccotrephes griseus(Hemiptera: Nepidae) was evaluated to establish its functional response against the immature Culexquinquefasciatus Say in the laboratory.Methods: Adult water bugs (L. griseus) were collected from different ponds in Bankura, West Bengal, India.Predation rate was determined in semi-field conditions. Functional response, regression equation analysis andrate of predation were also determined in the presence of an alternative prey.Results: The long-term predation experiment (up to 30 days) revealed that L. griseus is a very good predatorof mosquito larvae. The functional curve analysis of L. griseus exhibited a Type II functional response. Theirhandling times and coefficient of attack rates were 29.37 min and 2.17 respectively. Regression equationsshowed that consumption rate was directly proportional to prey and predator densities and inversely proportionalto the search area. The selectivity index, niche width and food breadth were also determined.Interpretation and conclusion: The present study revealed that L. griseus can consume a good number ofmosquito larvae in the laboratory conditions. The long-term bioassay also indicates their predatory responseagainst mosquito larvae in the semi-field conditions. The result of selectivity index, niche width and foodbreadth were also highest for Cx. quinquefasciatus. In these respects, the water bugs L. griseus are indicativeof their release in the aquatic habitat where Cx. quinquefasciatus is the most dominant mosquito species.
On the Nature of the Average Transverse Momenta of the Low-pT Secondaries in Some High Energy Nuclear Collisions  [PDF]
Amar Chandra Das Ghosh, Goutam Sau, Pradeepta Guptaroy, Subrata Bhattacharyya
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.38109
Abstract: That the values of average transverse momenta ( ) of the secondaries produced in high energy collisions rise very slowly with energy is modestly well-known and accepted. We would like to probe into this aspect of the problem for production of the main variety of the 'soft' secondaries in two high energy symmetric nuclear collisions with the help of two non-QCD models. Our model-based results are found to be quite consistent with the anticipated behaviours and also with the observations.
Characteristics of Strange Hadron Production in Some High Energy Collisions and the Role of Power Laws  [PDF]
Sunil Kumar Biswas, Goutam Sau, Amar Chandra Das Ghosh, Subrata Bhattacharyya
Open Journal of Microphysics (OJM) , 2012, DOI: 10.4236/ojm.2012.21001
Abstract: Studies on “strange” particle production have always occupied a very important space in the domain of Particle Physics. This was and is so, just because of some conjectures about specially abundant or excess production of “strange” particles, at certain stages and under certain conditions arising out of what goes by the name of “Standard” model in Particle Physics. With the help of Hagedornian power laws we have attempted to understand and interpret here the nature of the pT-spectra for the strange particle production in a few high energy nuclear collisions, some interesting ratio-behaviors and the characteristics of the nuclear modification factors that are measured in laboratory experiments. After obtaining and analysing the final results we do not confront any peculiarities or oddities or extraneous excesses in the properties of the relevant observables with no left-over problems or puzzles. The model(s) used by us work(s) quite well for explaining the measured data.
Mosquito larvicidal activities of Solanum villosum berry extract against the dengue vector Stegomyia aegypti
Nandita Chowdhury, Anupam Ghosh, Goutam Chandra
BMC Complementary and Alternative Medicine , 2008, DOI: 10.1186/1472-6882-8-10
Abstract: Aqueous and polar/non-polar solvent extract of fresh, mature, green berries of S. villosum was tested against Stegomyia aegypti, a common vector of dengue fever. A phytochemical analysis of chloroform:methanol extract was performed to search for the active toxic ingredient. The lethal concentration was determined (log probit analysis) and compared with Malathion. The chemical nature of the active substance was also evaluated following ultraviolet-visual (UV-Vis) and infrared (IR) analysis.In a 72 hour bioassay experiment with the aqueous extract, the highest mortality was recorded in 0.5% extract. When the mortality of different solvent extracts was compared, the maximum (p < 0.05) mortality was recorded at a concentration of 50 ppm of chloroform:methanol extract (1:1, v/v). The larvicidal activity was lower when compared with the chemical insecticide, Malathion (p < 0.05). Results of regression analysis revealed that the mortality rate (Y) was positively correlated with the period of exposure (X) and the log probit analysis (95% confidence level) recorded lowest value (5.97 ppm) at 72 hours of exposure. Phytochemical analysis of the chlororm:methanol extract reported the presence of many bioactive phytochemicals. Two toxic compounds were detected having Rf = 0.82 (70% and 73.33% mortality in 24 and 48 hours, respectively) and Rf = 0.95 (40% and 50% mortality in 24 and 48 hours, respectively). IR analysis provided preliminary information about the steroidal nature of the active ingredient.S. villosum offers promise as potential bio control agent against S. aegypti particularly in its markedly larvicidal effect. The extract or isolated bioactive phytochemical could be used in stagnant water bodies for the control of mosquitoes acting as vector for many communicable diseases.Mosquitoes transmit several public health problems, such as malaria, filariasis, dengue and Japanese encephalitis, causing millions of deaths every year [1]. Stegomyia aegypti (= Aedes aegypti) is
Tribological Performance Optimization of Al-7.5% SiCp Composites Using the Taguchi Method and Grey Relational Analysis
Shouvik Ghosh,Prasanta Sahoo,Goutam Sutradhar
Journal of Composites , 2013, DOI: 10.1155/2013/274527
Abstract: The present study considers an experimental study of tribological performance of Al-7.5% SiCp metal matrix composite and optimization of tribological testing parameters based on the Taguchi method coupled with grey relational analysis. A grey relational grade obtained from grey relational analysis is used as a performance index to study the behaviour of Al-7.5% SiCp MMC with respect to friction and wear characteristics. The tribological experiments are carried out by utilizing the combinations of tribological test parameters based on the L27 Taguchi orthogonal design with three test parameters, namely, load, speed, and time. The material Al-7.5% SiCp metal matrix composite is developed by reinforcing LM6 aluminium alloy with 7.5% (by weight) SiC particle of 400 mesh size (~37?μm) in an electric melting furnace. It is observed that sliding time has a significant contribution in controlling the friction and wear behaviour of Al-7.5% SiCp MMC. Furthermore, all the interactions between the parameters have significant influence on tribological performance. A confirmation test is also carried out to verify the accuracy of the results obtained through the optimization problem. In addition, a scanning electron microscopy (SEM) test is performed on the wear tracks to study the wear mechanism. 1. Introduction In recent years, metal matrix composites have gained popularity for use in industrial applications. The metal matrix composites have become increasingly desirable to engineers, largely due to improved toughness, strength, and stiffness properties offered by these materials relative to the unreinforced base metals. Mostly light metals such as aluminium, magnesium, and their alloys have received the commercial recognition due to their relatively low cost and easy processing. Arguably, aluminium based composites have shown performance improvements in a variety of applications requiring high strength, low mass, and tailored thermal properties. In the past years, many researchers have studied the friction and wear behaviour of Al based composites. Mostly, researchers have studied the friction and wear behaviour for sliding contact [1–6]. Some of the researchers have studied the abrasive wear behaviour for the same [7–12]. The effect of heat treatment [13, 14] and temperature change [15] is also studied by some researchers. Ma et al. [1] conducted wear test with block-on-ring configuration for Al-20% SiCp (particulate) and Al-50% SiCp. From the tests, they reported that wear increases with the increase in load and sliding speed, while wear decreases with the
Friction Performance of Al-10%SiCp Reinforced Metal Matrix Composites Using Taguchi Method
Shouvik Ghosh,Prasanta Sahoo,Goutam Sutradhar
ISRN Tribology , 2013, DOI: 10.5402/2013/386861
Abstract: The present paper considers the friction performance of Al-10%SiCp reinforced metal matrix composites against steel for varying tribological test parameters. The composite is prepared by stir-casting process using aluminium alloy LM6 being mixed with 10% silicon carbide by weight. The tribological tests are performed by varying applied load, sliding speed, and time. The friction performance is studied using plate-on-roller configuration in a multitribotester and optimized using Taguchi L27 orthogonal array. Analysis of variance (ANOVA) is performed to observe the significance of test parameters and their interactions on friction performance. It is observed that normal load and the interaction between normal load and speed influence the friction behaviour, significantly. The wear tracks are analyzed with the help of scanning electron microscopy. 1. Introduction Particle reinforced composites are recognized as a light weight material having enhanced mechanical and tribological properties than the constituent materials. The MMC (metal matrix composite) materials attain the toughness of the alloy matrix and hardness, stiffness, and strength of the reinforcement. Researchers [1–3] have used different types of aluminium alloys for synthesis of the composites. Also, different types of silicon carbide reinforcement such as particle, whisker, and fibre reinforcement are used by researchers. Mainly reinforcement volume fraction is varied by most researchers. Ahlatci et al. [4] carried out tribological experiments by mixing reinforcement in the volume fraction range from 0 to 60%. But most researchers [5–7] used volume fraction ranging from 1 to 20% for their study. The composites, synthesised by mixing the base metal and reinforcement, have greater strength, improved stiffness, improved corrosion resistance, and improved wear resistance. However, the relatively poor seizure resistance of aluminium alloy has restricted to uses in some engineering applications. These materials are good alternative to the traditional materials due to the improved properties. The increasing use of composite materials in the automobile and aeronautics fields is due to good friction and wear properties. In aeronautics, it is used for manufacturing of rotor blades due to increased creep resistance. The aluminium composites exhibit lower friction coefficient than their base alloys [8, 9]. Iwai et al. [6] conducted the study with 2024 Al alloy reinforced with 10% vol SiC. The friction study showed that initially the friction coefficient value is around 0.6 for both 2024?Al alloy and
Medicinal uses and pharmacological properties of Moringa oleifera
P Sudhir Kumar,Debasis Mishra,Goutam Ghosh,Chandra S. Panda
International Journal of Phytomedicine , 2011,
Abstract: Moringa oleifera Lam [Moringaceae] is a highly valued plant, distributed in many countries of the tropics and subtropics. It has an impressive range of medicinal uses with high nutritional value. Different parts of this plant contain a profile of important minerals, and are a good source of protein, vitamins, β -carotene, aminoacids and various phenolics. In addition to its compelling water purifying powers and high nutritional value, M. oleifera is very important for its medicinal value. Various parts of this plant such as the leaves, roots, seed, bark, fruit, flowers and immature pods act as cardiac and circulatory stimulants, possess anitumor, antipyretic, antiepileptic, antiinflammatory, antiulcer, antispasmodic, diuretic, antihypertensive, cholesterol lowering, antioxidant, antidiabetic, hepatoprotective, antibacterial and antifungal activities, and are being employed for the treatment of different ailments in the indigenous system of medicine. This review focuses on the detailed phytochemical composition, medicinal uses, along with pharmacological properties of different parts of this multipurpose tree. Keywords: Moringa oleifera; β –carotene; anitumor
Evidence of Conformational Changes in Adsorbed Lysozyme Molecule on Silver Colloids
Goutam Chandra,Kalyan S. Ghosh,Swagata Dasgupta,Anushree Roy
Physics , 2010,
Abstract: In this article, we discuss metal-protein interactions in the Ag-lysozyme complex by spectroscopic measurements. The analysis of the variation in relative intensities of SERS bands reveal the orientation and the change in conformation of the protein molecules on the Ag surface with time. The interaction kinetics of metal-protein complexes has been analyzed over a period of three hours via both Raman and absorption measurements. Our analysis indicates that the Ag nanoparticles most likely interact with Trp-123 which is in close proximity to Phe-34 of the lysozyme molecule.
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