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Fuzzy Hilbert adjoint operator and its properties
Subhendu Ghosal,Tarapada Bag 원광대학교 기초자연과학연구소 2018 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.15 No.3
In this paper, definition of fuzzy real Hilbert adjoint operator is given and some of its properties are studied. We also prove existence theorem for fuzzy real Hilbert adjoint operator.
Process Modeling and Optimization Studies in Drying of Current Transformers
Subhendu Bhattacharya,Dawid DMelo,Lokesh Chaudhari,Ram Avatar Sharma,Sarojini Swain 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.6
The vacuum drying process for drying of paper in current transformers was modeled with an aim to develop an understanding of the drying mechanism involved and also to predict the water collection rates . A molecular as well as macroscopic approach was adopted for the prediction of drying rate. Ficks law of diffusion was adopted for the prediction of drying rates at macroscopic levels. A steady state and dynamic mass transfer simulation was performed. The bulk diffusion coefficient was calculated using weight loss experiments. The accuracy of the solution was a strong function of the relation developed to determine the equilibrium moisture content. The actually observed diffusion constant was also important to predict the plant water removal rate. Thermo gravimetric studies helped in calculating the diffusion constant. In addition, simulation studies revealed the formation of perpetual moisture traps (loops)inside the CT. These loops can only be broken by changing the temperature or pressure of the system. The change in temperature or pressure changes the kinetic or potential energy of the effusing vapor resulting in breaking of the loop. The cycle was developed based on this mechanism. Additionally, simulation studies also revealed that the actual mechanism of moisture diffusion in CT’s is by surface jumps initiated by surface diffusion balanced against the surrounding pressure. Every subsequent step in the cycle was to break such loops. The effect of change in drying time on the electrical properties of the insulation was also assessed. The measurement of capacitance at the rated voltage and one third of the rated voltage demonstrated that the capacitance change is within the acceptance limit. Hence,the new cycle does not affect the electrical performance of the CT.
Process Modeling and Optimization Studies in Drying of Current Transformers
Bhattacharya, Subhendu,D'Melo, Dawid,Chaudhari, Lokesh,Sharma, Ram Avatar,Swain, Sarojini The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.6
The vacuum drying process for drying of paper in current transformers was modeled with an aim to develop an understanding of the drying mechanism involved and also to predict the water collection rates. A molecular as well as macroscopic approach was adopted for the prediction of drying rate. Ficks law of diffusion was adopted for the prediction of drying rates at macroscopic levels. A steady state and dynamic mass transfer simulation was performed. The bulk diffusion coefficient was calculated using weight loss experiments. The accuracy of the solution was a strong function of the relation developed to determine the equilibrium moisture content. The actually observed diffusion constant was also important to predict the plant water removal rate. Thermo gravimetric studies helped in calculating the diffusion constant. In addition, simulation studies revealed the formation of perpetual moisture traps (loops) inside the CT. These loops can only be broken by changing the temperature or pressure of the system. The change in temperature or pressure changes the kinetic or potential energy of the effusing vapor resulting in breaking of the loop. The cycle was developed based on this mechanism. Additionally, simulation studies also revealed that the actual mechanism of moisture diffusion in CT's is by surface jumps initiated by surface diffusion balanced against the surrounding pressure. Every subsequent step in the cycle was to break such loops. The effect of change in drying time on the electrical properties of the insulation was also assessed. The measurement of capacitance at the rated voltage and one third of the rated voltage demonstrated that the capacitance change is within the acceptance limit. Hence, the new cycle does not affect the electrical performance of the CT.
Fatty Acids and Phytochemical Components of Ipomoea spp. Seeds
Saubhik Das,Subhendu Narayan Ganguly,Kalyan Kumar Mukherjee 한국생약학회 1999 Natural Product Sciences Vol.5 No.3
Twelve species of Ipomoea were investigated for allelopathic behavior. Seed extracts of 1. quamoclit, 1. nil and 1. pes-tigridis showed significant allelopathy over germination of other seeds. Investigation on seed extracts of 1, quamoclit revealed the presence of several phytoehemical components viz., n-triacontanol, sitosterol, stigmasterol, α-amyrin, taraxerone, taraxerol, erythrodiol, cucurbitacin-G. Seed fat of twelve species were also analyzed.
Manish Debbarma,Subhendu Das,Bimal Debnath,Debankita Ghosh,Sayantika Chanda,Rahul Bhattacharjee,Surya Chattopadhyaya 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
Density functional calculations are carried out on elastic and thermal properties of zinc-blende specimens within HgxCd1−xS,HgxCd1−xSe and HgxCd1−xTe ternary systems. Elastic stiffness constants decrease almost linearly with increasing Hg-concentrationin each system. Each cubic sample is mechanically and dynamically stable, elastically anisotropic, compressibleagainst elastic deformation, ductile and fairly plastic. The hardness of specimens in each system reduces almost linearly withenhancement in Hg-composition. Mixed kind of bonding with dominancy of ionic bonding over covalent, central nature ofinteratomic forces and bond bending over stretching exist in all specimens. In each system, covalency, Debye temperature andfrequency, Debye temperature for acoustic phonon, thermal conductivity and melting temperature of specimens decreases,while Philip ionicity and Gruneisen parameter increases with increasing Hg-concentration.
Erosion dynamics of faceted pyramidal surfaces
Prabhjeet Kaur Dhillon,Subhendu Sarkar 한국물리학회 2016 Current Applied Physics Vol.16 No.9
Anisotropic etching using aqueous KOH was carried out on n-type Si (100) surfaces. Atomic force microscopy (AFM) was employed to study the etched surfaces for different times. The AFM data was investigated employing dynamic scaling theory formalism. The rms roughness was found to increase with etching time except for 2 min. Roughness exponent calculations revealed that the surface became locally rougher for etching times upto 4 min after which the local roughness decreases and the system ceases to obey Family-Vicsek scaling condition. A high value (~1.882) of the growth exponent b indicates a rapid out-of-plane growth as well as faceting of the pyramids on the surface. The surface roughness evolution is found to follow an eroding system characterized by quenched random fluctuations. Finally, a vacuum annealing study done up to 1000 C reveals that atoms having lower binding energies tend to get dislodged and diffuse from about 900 C.
Effect of Nano/micro Silica on Electrical Property of Unsaturated Polyester Resin Composites
Sharma, Ram Avatar,D'Melo, Dawid,Bhattacharya, Subhendu,Chaudhari, Lokesh,Swain, Sarojini The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.1
The addition of nano/micro silica into unsaturated polyester resin (UPR) results in the improvement of the electrical properties of Silica-UPR composites. The surface, volume resistivity, dielectric strength, dissipation factor and dry arc resistivity of nano silica-UPR composites were found to improve significantly. The effects of the nano and micro fillers in UPR have been evaluated. They are presented in this paper. To evaluate the electrical properties of the nano & micro composites, all the measurements were done as per the prescribed methods in ASTM. It was observed that the addition of nano silica improves the electrical properties as compared to micro silica. The better dispersion of silica particles in unsaturated polyester resin enhances the electrical properties of silica-UPR composites.
Effect of Nano/micro Silica on Electrical Property of Unsaturated Polyester Resin Composites
Ram Avatar Sharma,Dawid D Melo,Subhendu Bhattacharya,Lokesh Chaudhari,Sarojini Swain 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.1
The addition of nano/micro silica into unsaturated polyester resin (UPR) results in the improvement of the electrical properties of Silica-UPR composites. The surface, volume resistivity, dielectric strength, dissipation factor and dry arc resistivity of nano silica-UPR composites were found to improve significantly. The effects of the nano and micro fillers in UPR have been evaluated. They are presented in this paper. To evaluate the electrical properties of the nano µ composites, all the measurements were done as per the prescribed methods in ASTM. It was observed that the addition of nano silica improves the electrical properties as compared to micro silica. The better dispersion of silica particles in unsaturated polyester resin enhances the electrical properties of silica-UPR composites.
Swain, Sarojini,Sharma, Ram Avatar,Bhattacharya, Subhendu,Chaudhary, Lokesh The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.1
The present approach shows the use of nano-silica/nano-alumina in polyurethane (PU) matrix, which lead to significant improvements in the mechanical and thermal properties of the nano-composite. It is observed that with incorporation of 1% of nano-alumina into the PU matrix, there is an improvement in the tensile strength of around 50%, and for nano-silica the improvement is around 41%, at the same concentration. The morphological data shows that above 3% of the nano particles there are agglomerations in the nanocomposite. Again with the absorption of moisture, there is a decrease in the thermal and mechanical properties of the PU resin, but in this research work it is observed that with the incorporation of the nano particles, in the presence of absorbed moisture there is an improvement in mechanical and thermal properties of the composite, over that of the PU matrix.
Sarojini Swain,Ram Avatar Sharma,Sandip Patil,Subhendu Bhattacharya,Srinivasa Pavan Gadiyaram,Lokesh Chaudhari 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.6
Considering the properties of the carbon nano tubes (CNT), their inclusion into the polymer matrix vastly increases the properties of the resultant composite. However, this is not the case due to the poor interfacial adhesion of the CNT and the polymer matrix. The present approach focuses on increasing the interaction between the polymer matrix and the CNT through the chemical modification of the CNT resulting in allyl ester functionalized carbon nanotubes (ACNT)and silane functionalized carbon nano tubes (SCNT) which are capable of reacting with the polymer matrix during the curing reaction. The addition of ACNT/SCNT into unsaturated polyester resin (UPR) resulted in the improvement of the electrical properties of resulted nanocomposites in comparison to the CNT. The surface resistivity, volume resistivity, dielectric strength, dry arc resistivity, and the comparative tracking index of the nanocomposites were significantly improved in comparison to CNT. The chemical modification of CNT was confirmed via spectroscopy.