Fuzzy finite element method for solving uncertain heat conduction problems

Chakraverty, S.,Nayak, S. Techno-Press 2012 Coupled systems mechanics Vol.1 No.4

In this article we have presented a unique representation for interval arithmetic. The traditional interval arithmetic is transformed into crisp by symbolic parameterization. Then the proposed interval arithmetic is extended for fuzzy numbers and this fuzzy arithmetic is used as a tool for uncertain finite element method. In general, the fuzzy finite element converts the governing differential equations into fuzzy algebraic equations. Fuzzy algebraic equations either give a fuzzy eigenvalue problem or a fuzzy system of linear equations. The proposed methods have been used to solve a test problem namely heat conduction problem along with fuzzy finite element method to see the efficacy and powerfulness of the methodology. As such a coupled set of fuzzy linear equations are obtained. These coupled fuzzy linear equations have been solved by two techniques such as by fuzzy iteration method and fuzzy eigenvalue method. Obtained results are compared and it has seen that the proposed methods are reliable and may be applicable to other heat conduction problems too.

Free vibration analysis of elliptic and circular plates having rectangular orthotropy

Chakraverty, S.,Petyt, M. Techno-Press 1999 Structural Engineering and Mechanics, An Int'l Jou Vol.7 No.1

The natural frequencies and modes of free vibration of specially orthotropic elliptic and circular plates are analysed using the Rayleigh-Ritz method. The assumed functions used are two-dimensional boundary characteristic orthogonal polynomials which are generated using the Gram-Schmidt orthogonalization procedure. The first five natural frequencies are reported here for various values of aspect ratio of the ellipse. Results are given for various boundary conditions at the edges i.e., the boundary may be any of clamped, simply-supported or fret. Numerical results are presented here for several orthotropic material properties. For rectilinear orthotropic circular plates, a few results are available in the existing literature, which are compared with the present results and are found to be in good agreement.

The host environment regulates the function of CD8+ graft-versus-host-reactive effector cells.

Chakraverty, Ronjon,Flutter, Barry,Fallah-Arani, Farnaz,Eom, Hyeon-Seok,Means, Terry,Andreola, Giovanna,Schwarte, Sebastian,Buchli, Jennifer,Cotter, Pete,Zhao, Guiling,Sykes, Megan Williams Wilkins 2008 JOURNAL OF IMMUNOLOGY Vol.181 No.10

<P>We have examined how the host environment influences the graft-vs-leukemia (GVL) response following transfer of donor T cells to allogeneic chimeras. Donor T cells induce significant GVL when administered in large numbers to established mixed chimeras (MC). However, when using limiting numbers of T cells, we found that late transfer to MC induced less GVL than did early transfer to freshly irradiated allogeneic recipients. Late donor T cell transfer to MC was associated with marked accumulation of anti-host CD8 cells within the spleen, but delayed kinetics of differentiation, reduced expression of effector molecules including IFN-gamma, impaired cytotoxicity, and higher rates of sustained apoptosis. Furthermore, in contrast to the spleen, we observed a significant delay in donor CD8 cell recruitment to the bone marrow, a key location for hematopoietic tumors. Increasing the numbers of T cells transferred to MC led to the enhancement of CTL activity and detectable increases in absolute numbers of IFN-gamma(+) cells without inducing graft-vs-host disease (GVHD). TLR-induced systemic inflammation accelerated differentiation of functional CTL in MC but was associated with severe GVHD. In the absence of inflammation, both recipient T and non-T cell populations impeded the full development of GVHD-inducing effector function. We conclude that per-cell deficits in the function of donor CD8 cells activated in MC may be overcome by transferring larger numbers of T cells without inducing GVHD.</P>

Prediction of product parameters of fly ash cement bricks using two dimensional orthogonal polynomials in the regression analysis

S. Chakraverty,Himani Saini,S. K. Panigrahi 사단법인 한국계산역학회 2008 Computers and Concrete, An International Journal Vol.5 No.5

This paper focuses on the application of two dimensional orthogonal polynomials in the regression analysis for the relationship of product parameters viz. compressive strength, bulk density and water absorption of fly ash cement bricks with other process parameters such as percentages of fly ash, sand and cement. The method has been validated by linear and non-linear two parameter regression models. The use of two dimensional orthogonal system makes the analysis computationally efficient, simple and straight forward. Corresponding co-efficient of determination and F-test are also reported to show the efficacy and reliability of the relationships. By applying the evolved relationships, the product parameters of fly ash cement bricks may be approximated for the use in construction sectors.

Small scale effect on the vibration of non-uniform nanoplates

S. Chakraverty,Laxmi Behera 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.3

Free vibration of non-uniform embedded nanoplates based on classical (Kirchhoff’s) plate theory in conjunction with nonlocal elasticity theory has been studied. The nanoplate is assumed to be rested on two-parameter Winkler-Pasternak elastic foundation. Non-uniform material properties of nanoplates have been considered by taking linear as well as quadratic variations of Young’s modulus and density along the space coordinates. Detailed analysis has been reported for all possible cases of such variations. Trial functions denoting transverse deflection of the plate are expressed in simple algebraic polynomial forms. Application of the present method converts the problem into generalised eigen value problem. The study aims to investigate the effects of non-uniform parameter, elastic foundation, nonlocal parameter, boundary condition, aspect ratio and length of nanoplates on the frequency parameters. Three- dimensional mode shapes for some of the boundary conditions have also been illustrated. One may note that present method is easier to handle any sets of boundary conditions at the edges.

Performance Analysis of CMOS Single Ended Low Power Low Noise Amplifier

Mayank Chakraverty,Sandeep Mandava,Gargi Mishra 보안공학연구지원센터 2010 International Journal of Control and Automation Vol.3 No.2

Approximate solution of fuzzy quadratic Riccati differential equations

Tapaswini, Smita,Chakraverty, S. Techno-Press 2013 Coupled systems mechanics Vol.2 No.3

This paper targets to investigate the solution of fuzzy quadratic Riccati differential equations with various types of fuzzy environment using Homotopy Perturbation Method (HPM). Fuzzy convex normalized sets are used for the fuzzy parameter and variables. Obtained results are depicted in term of plots to show the efficiency of the proposed method.

Natural convection of nanofluid flow between two vertical flat plates with imprecise parameter

Biswal, U.,Chakraverty, S.,Ojha, B.K. Techno-Press 2020 Coupled systems mechanics Vol.9 No.3

Natural convection of nanofluid flow between two vertical flat plates has been analyzed in uncertain environment.Anon-Newtonian fluid SodiumAlginate (SA) as base fluid and nanoparticles ofCopper(Cu) are taken into consideration. In thepresentstudy,we have takennanoparticle volume fraction as an uncertain parameterin terms offuzzy number. Fuzzy uncertainties are controlled by r-cut and parametric concept. Homotopy PerturbationMethod (HPM) has been used to solve the governing fuzzy coupleddifferential equationsforthe titled problem.Forvalidation, presentresults are comparedwith existingresultsforsome special casesviz. crisp case andthey are foundto be ingood agreement.

Free vibration of functionally graded thin elliptic plates with various edge supports

K.K. Pradhan,S. Chakraverty 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.2

In this article, free vibration of functionally graded (FG) elliptic plates subjected to various classical boundary conditions has been investigated. Literature review reveals no study has been performed based on functionally graded elliptic plates till date. The mechanical kinematic relations are considered based on classical plate theory. Rayleigh-Ritz technique is used to obtain the generalized eigenvalue problem. The material properties of the FG plate are assumed to vary along thickness direction of the constituents according to power-law form. Trial functions denoting the displacement components are expressed in simple algebraic polynomial forms which can handle any edge support. The objective is to study the effect of geometric configurations and gradation of constituent volume fractions on the natural frequencies. New results for frequency parameters are incorporated after performing a test of convergence. A comparison study is carried out with existing literature for validation in special cases. Three-dimensional mode shapes for circular and elliptic FG plates are also presented with various boundary conditions at the edges.

Damage detection of multi-storeyed shear structure using sparse and noisy modal data

S.K. Panigrahi,S. Chakraverty,S.K. Bhattacharyya 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.5

In the present paper, a method for identifying damage in a multi storeyed shear building structure is presented using minimum number of modal parameters of the structure. A damage at any level of the structure may lead to a major failure if the damage is not attended at appropriate time. Hence an early detection of damage is essential. The proposed identification methodology requires experimentally determined sparse modal data of any particular mode as input to detect the location and extent of damage in the structure. Here, the first natural frequency and corresponding partial mode shape values are used as input to the model and results are compared by changing the sensor placement locations at different floors to conclude the best location of sensors for accurate damage identification. Initially experimental data are simulated numerically by solving eigen value problem of the damaged structure with inclusion of random noise on the vibration characteristics. Reliability of the procedure has been demonstrated through a few examples of multi storeyed shear structure with different damage scenarios and various noise levels. Validation of the methodology has also been done using dynamic data obtained through experiment conducted on a laboratory scale steel structure.