Purification and Characterization of a Deoxyriboendonuclease fromMycobacterium smegmatis

Phulghuri Chakraborty,Nitai Chandra Mandal,Prajna Mandal,Subrata Sau 한국생화학분자생물학회 2006 BMB Reports Vol.39 No.2

Robust design of liquid column vibration absorber in seismic vibration mitigation considering random system parameter

Debbarma, Rama,Chakraborty, Subrata Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.6

The optimum design of liquid column dampers in seismic vibration control considering system parameter uncertainty is usually performed by minimizing the unconditional response of a structure without any consideration to the variation of damper performance due to uncertainty. However, the system so designed may be sensitive to the variations of input system parameters due to uncertainty. The present study is concerned with robust design optimization (RDO) of liquid column vibration absorber (LCVA) considering random system parameters characterizing the primary structure and ground motion model. The RDO is obtained by minimizing the weighted sum of the mean value of the root mean square displacement of the primary structure as well as its standard deviation. A numerical study elucidates the importance of the RDO procedure for design of LCVA system by comparing the RDO results with the results obtained by the conventional stochastic structural optimization procedure and the unconditional response based optimization.

Markov Chain Monte Carlo simulation based Bayesian updating of model parameters and their uncertainties

Partha Sengupta,Subrata Chakraborty 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.1

The prediction error variances for frequencies are usually considered as unknown in the Bayesian system identification process. However, the error variances for mode shapes are taken as known to reduce the dimension of an identification problem. The present study attempts to explore the effectiveness of Bayesian approach of model parameters updating using Markov Chain Monte Carlo (MCMC) technique considering the prediction error variances for both the frequencies and mode shapes. To remove the ergodicity of Markov Chain, the posterior distribution is obtained by Gaussian Random walk over the proposal distribution. The prior distributions of prediction error variances of modal evidences are implemented through inverse gamma distribution to assess the effectiveness of estimation of posterior values of model parameters. The issue of incomplete data that makes the problem ill-conditioned and the associated singularity problem is prudently dealt in by adopting a regularization technique. The proposed approach is demonstrated numerically by considering an eight-storey frame model with both complete and incomplete modal data sets. Further, to study the effectiveness of the proposed approach, a comparative study with regard to accuracy and computational efficacy of the proposed approach is made with the Sequential Monte Carlo approach of model parameter updating.

Purification and Characterization of a Deoxyriboendonuclease from Mycobacterium smegmatis

Mandal, Prajna,Chakraborty, Phulghuri,Sau, Subrata,Mandal, Nitai Chandra Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.2

A deoxyriboendonuclease has been purified to near homogeneity from a fast growing mycobacterium species, M. smegmatis and characterized to some extent. The size of enzyme is about 43 kDa as determined by a denaturing gel analysis. It shows optimum activity at $32^{\circ}C$ in Tris-HCl buffer (pH 7.2) containing 2.5 mM of $MgCl_2$. Both EDTA and $K^+$ but not $Na^+$ inhibit its activity. Evidences show that the enzyme is not a restriction endonuclease but catalyzes the endonucleolytic cleavage of both the double- as well as the single-strand DNA non-specifically. It has been shown that the cleavage by this enzyme generates DNA fragments carrying phosphate groups at 5' ends and hydroxyl group at the 3' ends, respectively. Analysis reveals that no endonuclease having size and property identical to our deoxyriboendonuclease had been purified from M. smegmatis before. The property of our enzymes closely matches with the deoxyriboendonucleases purified from diverse sources including bacteria.

Robust design of liquid column vibration absorber in seismic vibration mitigation considering random system parameter

Rama Debbarma,Subrata Chakraborty 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.6

The optimum design of liquid column dampers in seismic vibration control considering systemparameter uncertainty is usually performed by minimizing the unconditional response of a structure withoutany consideration to the variation of damper performance due to uncertainty. However, the system sodesigned may be sensitive to the variations of input system parameters due to uncertainty. The present studyis concerned with robust design optimization (RDO) of liquid column vibration absorber (LCVA)considering random system parameters characterizing the primary structure and ground motion model. TheRDO is obtained by minimizing the weighted sum of the mean value of the root mean square displacementof the primary structure as well as its standard deviation. A numerical study elucidates the importance of theRDO procedure for design of LCVA system by comparing the RDO results with the results obtained by theconventional stochastic structural optimization procedure and the unconditional response basedoptimization.

Purification and Characterization of a Deoxyriboendonuclease from Mycobacterium smegmatis

Prajna Mandal,Phulghuri Chakraborty,Subrata Sau,Nitai Chandra Mandal 한국생활환경학회 2006 BMB Reports Vol.39 No.2

Optimal design of Base Isolation System considering uncertain bounded system parameters

Roy, Bijan Kumar,Chakraborty, Subrata Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.1

The optimum design of base isolation system considering model parameter uncertainty is usually performed by using the unconditional response of structure obtained by the total probability theory, as the performance index. Though, the probabilistic approach is powerful, it cannot be applied when the maximum possible ranges of variations are known and can be only modelled as uncertain but bounded type. In such cases, the interval analysis method is a viable alternative. The present study focuses on the bounded optimization of base isolation system to mitigate the seismic vibration effect of structures characterized by bounded type system parameters. With this intention in view, the conditional stochastic response quantities are obtained in random vibration framework using the state space formulation. Subsequently, with the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem is transformed to appropriate deterministic optimization problems correspond to a lower bound and upper bound optimum solutions. A lead rubber bearing isolating a multi-storeyed building frame is considered for numerical study to elucidate the proposed bounded optimization procedure and the optimum performance of the isolation system.

Reliability analysis of laminated composite shells by response surface method based on HSDT

Sandipan N. Thakur,Subrata Chakraborty,Chaitali Ray 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.2

Reliability analysis of composite structures considering random variation of involved parameters is quite important as composite materials revealed large statistical variations in their mechanical properties. The reliability analysis of such structures by the first order reliability method (FORM) and Monte Carlo Simulation (MCS) based approach involves repetitive evaluations of performance function. The response surface method (RSM) based metamodeling technique has emerged as an effective solution to such problems. In the application of metamodeling for uncertainty quantification and reliability analysis of composite structures; the finite element model is usually formulated by either classical laminate theory or first order shear deformation theory. But such theories show significant error in calculating the structural responses of composite structures. The present study attempted to apply the RSM based MCS for reliability analysis of composite shell structures where the surrogate model is constructed using higher order shear deformation theory (HSDT) of composite structures considering the uncertainties in the material properties, load, ply thickness and radius of curvature of the shell structure. The sensitivity of responses of the shell is also obtained by RSM and finite element method based direct approach to elucidate the advantages of RSM for response sensitivity analysis. The reliability results obtained by the proposed RSM based MCS and FORM are compared with the accurate reliability analysis results obtained by the direct MCS by considering two numerical examples.

Optimal design of Base Isolation System considering uncertain bounded system parameters

Bijan Kumar Roy,Subrata Chakraborty 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.1

The optimum design of base isolation system considering model parameter uncertainty is usually performed by using the unconditional response of structure obtained by the total probability theory, as the performance index. Though, the probabilistic approach is powerful, it cannot be applied when the maximum possible ranges of variations are known and can be only modelled as uncertain but bounded type. In such cases, the interval analysis method is a viable alternative. The present study focuses on the bounded optimization of base isolation system to mitigate the seismic vibration effect of structures characterized by bounded type system parameters. With this intention in view, the conditional stochastic response quantities are obtained in random vibration framework using the state space formulation. Subsequently, with the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem is transformed to appropriate deterministic optimization problems correspond to a lower bound and upper bound optimum solutions. A lead rubber bearing isolating a multi-storeyed building frame is considered for numerical study to elucidate the proposed bounded optimization procedure and the optimum performance of the isolation system.

Shock wave attenuation using sandwiched structures made up of polymer foams and shear thickening fluid

Kehar Singh,Rajat Raj,Arun Kumar Rajagopal,Sachin Jalwal,Subrata Chakraborty 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

The present study experimentally investigates the shock wave attenuation performance of various sandwiched structures made up of different polymer foams (expanded polystyrene and polyurethane foam) with and without shear thickening fluid (STF). STF is a non-Newtonian fluid whose viscosity increases with increase in shear rate due to the formation of hydro clusters produced by the increased hydrodynamic forces acting between the interstitial spaces. Two layers of polymer foams have been considered for the shock protective material and the space between the layers is filled with shear thickening fluid. The shock wave is experimentally generated from a shock tube facility and is allowed to impinge on a target plate kept at 10 mm downstream to the shock tube end. It is seen that the protective material with polyurethane foam and shear thickening fluid (polyethylene glycol+silica nanoparticles) reduces the shock overpressure by nearly 35.51 %, whereas the protective material with only polyurethane foam (with the same thickness) reduces the shock overpressure by only 13.17 %. Similarly, the protective material with expanded polystyrene and shear thickening fluid reduces the shock overpressure by nearly 32.16 %, whereas the protective material with only expanded polystyrene (with the same thickness) reduces the shock overpressure by only 10.49 %. Hence, it is evident that the shear thickening fluid between the polymer foam layers greatly helps in shock wave attenuation.