Siliguri Institute of Technology
Darjeeling, India

Siliguri Institute of Technology is a private engineering and management college, established in 1999 in Siliguri, West Bengal, India. Initially the college was under North Bengal University and from the year 2004 came under the control of the newly formed West Bengal University of Technology. The college is now a part of the Techno India Group. Wikipedia.

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Dasgupta P.,Siliguri Institute of Technology | Das B.,Siliguri Institute of Technology | Das M.K.,North Bengal University
Liquid Crystals | Year: 2012

The physical properties of three laterally fluorinated liquid crystalline compounds with negative dielectric anisotropy have been studied from static dielectric permittivity, optical birefringence, bend elastic constant, relaxation time and rotational viscosity measurements. Such negative dielectric anisotropy materials find use as components of mixtures for application in vertically aligned mode liquid crystal displays. Moreover, the physical properties of one phenyl cyclohexane compound with positive dielectric anisotropy have also been studied. A five-component mixture comprising these four mesogens and a non-mesogenic component has been formulated and its physical properties have been thoroughly investigated. An attempt has been made to strike a balance between the optical birefringence of the mixture to adjust the cell gap and the dielectric anisotropy and threshold voltage (V th) to ensure low driving voltages. The pretilt angle effect on the threshold voltage and the relaxation time has also been studied. At T = 20°C, the response time decreases to 22% and 41% for the mixture for 2° and 5° pretilt as compared to zero pretilt. On the other hand, at the same temperature the V th values are decreased by 5% and 9%, respectively. © 2012 Copyright Taylor and Francis Group, LLC.

Chakraborty A.,North Bengal University | Das M.K.,North Bengal University | Das B.,Siliguri Institute of Technology | Lehmann A.,Martin Luther University of Halle Wittenberg | Tschierske C.,Martin Luther University of Halle Wittenberg
Soft Matter | Year: 2013

Two simple but precise probing methods have been utilized to investigate the influence of structure, properties and molecular association on the director response time (τ0) and hence on the rotational viscosity (γ1) in the nematic phase of three 4-cyanoresorcinol bent-core derivatives (1/7, 1/9 and 1/10) having different terminal chain lengths. The results obtained from the two methods are in good agreement with a small deviation of about 10-15%. The γ1 values are more than an order of magnitude higher compared to the conventional calamitic nematics. Measurements of birefringence, dielectric anisotropy, splay and bend elastic constants and relaxation time of these compounds have also been carried out. For the lower homologues (1/7, 1/9) an inversion in dielectric anisotropy (Δε) is observed in the nematic phase, while the higher homologue (1/10) exhibits negative Δε throughout the entire mesomorphic range. The splay elastic constant (K11) is found to be comparatively greater than the bend elastic constant (K33); however, on approaching the low temperature CybC phase (a phase comprising elongated cybotactic clusters) K33 exhibits a small pretransitional divergence. For all three compounds the magnitude of the rotational viscosity coefficient (γ1) is found to exhibit a strong enhancement on approaching the CybC phase, while in the nematic phase activation energies are found to be nearly an order of magnitude higher than the normal calamitics. The observed behaviours are explained by considering the strong dipolar correlation of the bent-core molecules and the existence of the short range cybotactic clusters, their gradual growth and uniform alignment under the presence of strong surface anchoring. © 2013 The Royal Society of Chemistry.

Mahapatra G.S.,Siliguri Institute of Technology | Mahapatra B.S.,Seacom Engineering College
International Journal of Performability Engineering | Year: 2011

In this paper, redundancy allocation problem for system reliability has been presented with entropy as objective function. This model using entropy has been used to account for the lack of expert's information. The goal of entropy redundancy allocation problem is to find out optimal level of redundancies at each subsystem in a way that maximizes reliability and entropy of the system subject to specified system cost. Intuitionistic fuzzy optimization technique is used to analyze an entropy based reliability redundancy optimization problem. Numerical examples have been provided to illustrate the model. © RAMS Consultants.

Mahapatra G.S.,Siliguri Institute of Technology | Mandal T.K.,Bengal Engineering and Science University | Samanta G.P.,Bengal Engineering and Science University
International Journal of Machine Learning and Cybernetics | Year: 2011

In general, cost constant parameters of inventory or production models are not rigid in real life rather these are imprecise in nature. In this paper we have presented imprecise cost constant parameters for an economic production quantity model. The unit production cost of this economic production quantity model is demand and reliability dependent. The imprecise parameters of the production model are considered as fuzzy in nature. The fuzzy model is solved by fuzzy parametric geometric programming technique. Finally, production model is numerically illustrated using fuzzy parametric geometric programming. © 2011 Springer-Verlag.

De D.,MCKV Institute of Engineering | Panda P.K.,Siliguri Institute of Technology | Roy M.,Saha Institute of Nuclear Physics | Bhunia S.,Saha Institute of Nuclear Physics
Materials and Design | Year: 2013

Mechanochemically devulcanized ground rubber tire (GRT) was revulcanized in a composition with natural rubber (NR) and polybutadiene rubber (PBR). Reclaiming of GRT was carried out by tetra methyl thiuram disulfide (TMTD) in the presence of spindle oil, a paraffin base rubber process oil. The cure characteristics and tensile properties of NR/PBR compounds were investigated. Results indicate that the minimum torque and Mooney viscosity of the NR/PBR compounds increase with increasing reclaim rubber (RR) loading whereas the scorch time remains unaltered but optimum cure time exhibits a decreasing trend due to the presence of active crosslinking sites in the reclaim rubber. The (re)vulcanization of different NR-PBR/RR blends was found to give a new low cost product with adequate properties. The mechanical properties before and after aging of NR-PBR/RR blend system and different proportions of carbon black loaded NR-PBR/RR blend system were studied. Tensile strength increases with increasing the proportion of reclaim rubber, but for all the vulcanizates the values are less than those of the control formulation. Thermogravimetric analysis of RR, NR-PBR and different NR-PBR/RR vulcanizates was carried out in order to get thermal stability of the vulcanizates. The effects of variations of RR loading on dynamic mechanical properties like loss tangent, storage and loss modulus were studied. © 2012 Elsevier Ltd.

Mahapatra G.S.,Siliguri Institute of Technology | Mitra M.,Bengal Engineering and Science University | Roy T.K.,Bengal Engineering and Science University
International Journal of Fuzzy Systems | Year: 2010

This paper proposes an intuitionistic fuzzy optimization approach to solve a multi-objective nonlinear programming problem in the context of a reliability application. We have considered a multi-objective reliability optimization problem with reliability and cost as objective functions. Intuitionistic fuzzy optimization approach is used to solve this multi-objective reliability optimization model. It is shown that the proposed intuitionistic fuzzy optimization approach is more efficient than the analogous fuzzy technique. Numerical examples are provided to illustrate our approach. © 2010 TFSA.

Mahapatra G.S.,Siliguri Institute of Technology | Roy T.K.,Bengal Engineering and Science University
International Journal of Industrial and Systems Engineering | Year: 2014

In this paper, we have presented intuitionistic fuzzy optimisation technique to find out the optimum system reliability of complex systems subject to constraint on system cost. In general, the system costs as objective goal have not been stated clearly. Here the system cost is considered as intuitionistic fuzzy in nature. This imprecise reliability optimisation model is solved through the intuitionistic fuzzy optimisation method. It is shown that the intuititionistic fuzzy optimisation technique is more efficient in reliability optimisation than the analogous fuzzy technique. Examples are shown to illustrate the proposed method. © 2014 Inderscience Enterprises Ltd.

Pal D.,Chandrahati Dilip Kumar High School H.S. | Mahaptra G.S.,Siliguri Institute of Technology | Samanta G.P.,Bengal Engineering and Science University
Mathematical Biosciences | Year: 2013

The paper presents the study of one prey one predator harvesting model with imprecise biological parameters. Due to the lack of precise numerical information of the biological parameters such as prey population growth rate, predator population decay rate and predation coefficients, we consider the model with imprecise data as form of an interval in nature. Many authors have studied prey-predator harvesting model in different form, here we consider a simple prey-predator model under impreciseness and introduce parametric functional form of an interval and then study the model. We identify the equilibrium points of the model and discuss their stabilities. The existence of bionomic equilibrium of the model is discussed. We study the optimal harvest policy and obtain the solution in the interior equilibrium using Pontryagin's maximum principle. Numerical examples are presented to support the proposed model. © 2012 Elsevier Inc.

Mahapatra G.S.,Siliguri Institute of Technology | Mandal T.K.,Bengal Engineering and Science University | Samanta G.P.,Bengal Engineering and Science University
Journal of Multiple-Valued Logic and Soft Computing | Year: 2012

In this paper, an economic production quantity model with demand and reliability dependent unit production cost under limited available imprecise space has been developed. Flexibility and reliability considerations are introduced in the production process. The goal of the storage space of the economic production quantity model is taken as intuitionistic fuzzy in nature. The problem is solved based on an intuitionistic fuzzy optimization technique. A numerical example is given to illustrate the model using this intuitionistic fuzzy optimization technique. © 2012 Old City Publishing, Inc.

Mahapatra G.S.,Siliguri Institute of Technology | Roy T.K.,Bengal Engineering and Science University
Journal of Uncertain Systems | Year: 2013

We have introduced intuitionistic fuzzy number and its arithmetic operations based on extension principle of intuitionistic fuzzy sets. Here two types of intuitionistic fuzzy sets, namely triangular intuitionistic fuzzy number and trapezoidal intuitionistic fuzzy number is presented. We also present that the arithmetic operation of two or more intuitionistic fuzzy number is again an intuitionistic fuzzy number. The starting failure of an automobile system is presented by intuitionistic fuzzy system. Each components failure is represented by trapezoidal intuitionistic fuzzy number of the system failure model to compute the imprecise failure. Finally, the presented concepts are analyzed through suitable numerical example. © 2013 World Academic Press, UK. All rights reserved.

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