Pub Date : 2021-08-28DOI: 10.1080/15502287.2021.1964638
Reza Adelkhani, J. Ghanbari
Abstract Free transverse vibration of variable cross-section cantilever FG beams with nonlinear profiles is investigated in this paper. Four thickness functions, namely, linear, parabolic, sinusoidal, and exponential functions are assumed for variation of the cross-section of the beam. Linear and exponential grading rules for axially varying material properties are covered in this paper. The governing differential equation is solved using the weighted residual collocation method with the exact solution shape functions for the uniform beam as the trial functions. This choice for the trial functions showed an increase in the convergence rate. The Gauss–Legendre points are used as the collocation points to reduce the fluctuations in the convergence curve as usually encountered in the point collocation method. The effects of the taper parameter for all kinds of thickness functions on the natural frequencies are studied. The effects of various parameters, including taper parameter, profile, and grading function on the natural frequencies are investigated. Also, a series of finite element simulations are performed for comparison purposes. It is observed that the obtained results are in good agreement with the numerical simulations and available published data with vastly reduced computational cost as a result of using the collocation method.
{"title":"Vibration analysis of nonlinear tapered functionally graded beams using point collocation method","authors":"Reza Adelkhani, J. Ghanbari","doi":"10.1080/15502287.2021.1964638","DOIUrl":"https://doi.org/10.1080/15502287.2021.1964638","url":null,"abstract":"Abstract Free transverse vibration of variable cross-section cantilever FG beams with nonlinear profiles is investigated in this paper. Four thickness functions, namely, linear, parabolic, sinusoidal, and exponential functions are assumed for variation of the cross-section of the beam. Linear and exponential grading rules for axially varying material properties are covered in this paper. The governing differential equation is solved using the weighted residual collocation method with the exact solution shape functions for the uniform beam as the trial functions. This choice for the trial functions showed an increase in the convergence rate. The Gauss–Legendre points are used as the collocation points to reduce the fluctuations in the convergence curve as usually encountered in the point collocation method. The effects of the taper parameter for all kinds of thickness functions on the natural frequencies are studied. The effects of various parameters, including taper parameter, profile, and grading function on the natural frequencies are investigated. Also, a series of finite element simulations are performed for comparison purposes. It is observed that the obtained results are in good agreement with the numerical simulations and available published data with vastly reduced computational cost as a result of using the collocation method.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"905 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114049548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-09DOI: 10.1080/15502287.2021.1957041
F. P. Ewolo Ngak, G. Ntamack, L. Azrar
Abstract In this paper, the three-dimensional static behavior and the free vibration of simply supported multilayered functionally graded elastic plates with bonding imperfections is derived. The imperfect interfaces between the adjacent layers are modeled by the spring-type layer model. In each layer, a well-adapted semi-analytical solution coupling the state-space approach with the fourth-order Runge-Kutta numerical procedure is elaborated. In consequence, the intricate three-dimensional problem has been reduced to a one-dimensional recursive problemwith which arbitrary functionally graded material’s model and number of layers can be easily handled. The predicted solution in each layer has been propagated from the bottom to the top layers of the plate using the propagator matrix method and taking into account the transfer matrix at the imperfect interfaces. The transfer relationship linking the top and the bottom surfaces of the multilayered functionally graded plate is therefore obtained. The accuracy and reliability of the proposed methodological approach have been clearly demonstrated by several numerical tests. The predicted numerical results have been well compared with the available ones obtained by the pseudo-Stroh formalism, discrete layer approach, finite elements method, Layerwise method, variable kinematic model, sinusoidal and hyperbolic shears deformations theories, respectively. These results showed that the imperfect interfaces have a strong effect on the static behavior and the natural frequencies of multilayered functionally graded plates. In addition, the obtained results showed that when the dimensionless interface parameter increase the natural frequencies decrease quickly.
{"title":"Semi-analytical solution for static and free vibration of multilayered functionally graded elastic plates with imperfect interfaces","authors":"F. P. Ewolo Ngak, G. Ntamack, L. Azrar","doi":"10.1080/15502287.2021.1957041","DOIUrl":"https://doi.org/10.1080/15502287.2021.1957041","url":null,"abstract":"Abstract In this paper, the three-dimensional static behavior and the free vibration of simply supported multilayered functionally graded elastic plates with bonding imperfections is derived. The imperfect interfaces between the adjacent layers are modeled by the spring-type layer model. In each layer, a well-adapted semi-analytical solution coupling the state-space approach with the fourth-order Runge-Kutta numerical procedure is elaborated. In consequence, the intricate three-dimensional problem has been reduced to a one-dimensional recursive problemwith which arbitrary functionally graded material’s model and number of layers can be easily handled. The predicted solution in each layer has been propagated from the bottom to the top layers of the plate using the propagator matrix method and taking into account the transfer matrix at the imperfect interfaces. The transfer relationship linking the top and the bottom surfaces of the multilayered functionally graded plate is therefore obtained. The accuracy and reliability of the proposed methodological approach have been clearly demonstrated by several numerical tests. The predicted numerical results have been well compared with the available ones obtained by the pseudo-Stroh formalism, discrete layer approach, finite elements method, Layerwise method, variable kinematic model, sinusoidal and hyperbolic shears deformations theories, respectively. These results showed that the imperfect interfaces have a strong effect on the static behavior and the natural frequencies of multilayered functionally graded plates. In addition, the obtained results showed that when the dimensionless interface parameter increase the natural frequencies decrease quickly.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121307521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-23DOI: 10.1080/15502287.2021.1954726
Mamta Kapoor, V. Joshi
Abstract The aim of present study is to develop a numerical scheme by using the notion of Barycentric Lagrange interpolation based Differential quadrature method to solve the coupled 1D Burgers’ equation. This method reduced the mentioned partial differential equation into the set of ordinary differential equations, which can be dealt by the SSP-RK43 scheme. The proposed method has been implemented upon the different numerical examples in order to test the accuracy and effectiveness of the proposed method. It is observed that obtained results are in good compatibility with the exact solution and are better than the previous results. The stability of the proposed method is also discussed by using the matrix stability analysis method, which represents that the proposed method is unconditionally stable.
{"title":"Numerical solution of coupled 1D Burgers’ equation by employing Barycentric Lagrange interpolation basis function based differential quadrature method","authors":"Mamta Kapoor, V. Joshi","doi":"10.1080/15502287.2021.1954726","DOIUrl":"https://doi.org/10.1080/15502287.2021.1954726","url":null,"abstract":"Abstract The aim of present study is to develop a numerical scheme by using the notion of Barycentric Lagrange interpolation based Differential quadrature method to solve the coupled 1D Burgers’ equation. This method reduced the mentioned partial differential equation into the set of ordinary differential equations, which can be dealt by the SSP-RK43 scheme. The proposed method has been implemented upon the different numerical examples in order to test the accuracy and effectiveness of the proposed method. It is observed that obtained results are in good compatibility with the exact solution and are better than the previous results. The stability of the proposed method is also discussed by using the matrix stability analysis method, which represents that the proposed method is unconditionally stable.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114893292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-22DOI: 10.1080/15502287.2021.1949407
Srinivasa Raju Rallabandi
Abstract This research investigates the simultaneous effects of thermal diffusion and diffusion thermo on incompressible, viscous, electrically conducting non-Newtonian Casson fluid flow past a vertically inclined surface through a porous medium in the presence of the uniform transverse magnetic field, chemical reaction, viscous dissipation, and constant heat flux. The action of thermal radiation and viscous dissipation is scrutinized. The fundamental governing equations determining the flow condition are transfigured as nonlinear coupled partial differential equations through self-similarity transmutations. The finite element technique is implemented to acquire the solution to the problem. Graphs are plotted to inspect the influence of sundry physical quantities on the three routine profiles of the flow field. Further, expressions are procured for friction factor and the rate of heat and mass transfers and discussed comprehensively through tabular forms. Favorable comparisons with previously published work on various exceptional cases of the problem are obtained. This research shows that the Soret number increases both the velocity and concentration fields, and the Dufour number increases the velocity and temperature fields. It is also observed that concentration and velocity fields reduce toward chemical reaction parameter. Furthermore, the Schmidt number decreases the velocity and concentration profiles. It is also noteworthy that velocity decays for the magnetic variable. An improvement in radiation declines the velocity and temperature profiles.
{"title":"Finite element solutions of non-Newtonian dissipative Casson fluid flow past a vertically inclined surface surrounded by porous medium including constant heat flux, thermal diffusion, and diffusion thermo","authors":"Srinivasa Raju Rallabandi","doi":"10.1080/15502287.2021.1949407","DOIUrl":"https://doi.org/10.1080/15502287.2021.1949407","url":null,"abstract":"Abstract This research investigates the simultaneous effects of thermal diffusion and diffusion thermo on incompressible, viscous, electrically conducting non-Newtonian Casson fluid flow past a vertically inclined surface through a porous medium in the presence of the uniform transverse magnetic field, chemical reaction, viscous dissipation, and constant heat flux. The action of thermal radiation and viscous dissipation is scrutinized. The fundamental governing equations determining the flow condition are transfigured as nonlinear coupled partial differential equations through self-similarity transmutations. The finite element technique is implemented to acquire the solution to the problem. Graphs are plotted to inspect the influence of sundry physical quantities on the three routine profiles of the flow field. Further, expressions are procured for friction factor and the rate of heat and mass transfers and discussed comprehensively through tabular forms. Favorable comparisons with previously published work on various exceptional cases of the problem are obtained. This research shows that the Soret number increases both the velocity and concentration fields, and the Dufour number increases the velocity and temperature fields. It is also observed that concentration and velocity fields reduce toward chemical reaction parameter. Furthermore, the Schmidt number decreases the velocity and concentration profiles. It is also noteworthy that velocity decays for the magnetic variable. An improvement in radiation declines the velocity and temperature profiles.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130053842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-19DOI: 10.1080/15502287.2021.1949408
F. Abbaspour, H. Arvin, M. Shahriari-kahkeshi
Abstract This paper investigates on the active control of vibrations of rectangular nanocomposite micro plates reinforced with graphene platelet bonded with piezoelectric layers in thermal environment regarding the structural damping. The micro plate is subjected to a transverse load. The thermo-mechanical features of the reinforced layers are determined employing the Halpin-Tsai micromechanical model. The first order shear deformation theory is accompanied by the modified couple stress theory to derive the motion equations of the micro plate. The Ritz technique is applied to the governing equations to discretize the equations of motion. In order to active control of vibrations of the micro plate, a closed-loop PD-controller is proposed. For the sake of determination of the transient response, the Newmark- direct integration technique is applied to the discretized governing equations of motion ensuing from the Ritz technique. The present findings are validated with the available data in the literature. A parametric study is established to shed light on the impression of the material length scale parameter, the boundary condition type, the graphene platelet distribution pattern and its weight fraction, and the control gain values on the dynamic response of the micro plate when it is subjected to a pulse-uniformly distributed transverse force. The results illustrate the more effectiveness of the designed PD controller for X-GPL micro plates with four clamped boundaries especially when the size dependency is incorporated into the formulation. Moreover, the PD controller performance boosts up at higher temperatures.
{"title":"Active control of vibrations of piezoelectric rectangular nanocomposite micro plates reinforced with graphene platelet in thermal ambient considering the structural damping","authors":"F. Abbaspour, H. Arvin, M. Shahriari-kahkeshi","doi":"10.1080/15502287.2021.1949408","DOIUrl":"https://doi.org/10.1080/15502287.2021.1949408","url":null,"abstract":"Abstract This paper investigates on the active control of vibrations of rectangular nanocomposite micro plates reinforced with graphene platelet bonded with piezoelectric layers in thermal environment regarding the structural damping. The micro plate is subjected to a transverse load. The thermo-mechanical features of the reinforced layers are determined employing the Halpin-Tsai micromechanical model. The first order shear deformation theory is accompanied by the modified couple stress theory to derive the motion equations of the micro plate. The Ritz technique is applied to the governing equations to discretize the equations of motion. In order to active control of vibrations of the micro plate, a closed-loop PD-controller is proposed. For the sake of determination of the transient response, the Newmark- direct integration technique is applied to the discretized governing equations of motion ensuing from the Ritz technique. The present findings are validated with the available data in the literature. A parametric study is established to shed light on the impression of the material length scale parameter, the boundary condition type, the graphene platelet distribution pattern and its weight fraction, and the control gain values on the dynamic response of the micro plate when it is subjected to a pulse-uniformly distributed transverse force. The results illustrate the more effectiveness of the designed PD controller for X-GPL micro plates with four clamped boundaries especially when the size dependency is incorporated into the formulation. Moreover, the PD controller performance boosts up at higher temperatures.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"292 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131783990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-13DOI: 10.1080/15502287.2021.1948148
T. A. Bullo, G. Degla, G. Duressa
Abstract A parameter-uniform finite difference scheme is constructed and analyzed for solving singularly perturbed parabolic problems with two parameters. The solution involves boundary layers at both the left and right ends of the solution domain. A numerical algorithm is formulated based on uniform mesh finite difference approximation for time variable and appropriate piecewise uniform mesh for the spatial variable. The developed method is second-order convergent. Furthermore, the present method produces a more accurate solution than some methods.
{"title":"Parameter-uniform finite difference method for singularly perturbed parabolic problem with two small parameters","authors":"T. A. Bullo, G. Degla, G. Duressa","doi":"10.1080/15502287.2021.1948148","DOIUrl":"https://doi.org/10.1080/15502287.2021.1948148","url":null,"abstract":"Abstract A parameter-uniform finite difference scheme is constructed and analyzed for solving singularly perturbed parabolic problems with two parameters. The solution involves boundary layers at both the left and right ends of the solution domain. A numerical algorithm is formulated based on uniform mesh finite difference approximation for time variable and appropriate piecewise uniform mesh for the spatial variable. The developed method is second-order convergent. Furthermore, the present method produces a more accurate solution than some methods.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127217082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-09DOI: 10.1080/15502287.2021.1948149
Guru Anandan, V. Gopalan, S. Natarajan
Abstract Nowadays natural fibre reinforced composite plates are shown importance due to its eco-friendly nature. If natural fibre reinforced composite is manufactured properly, it will be a suitable replacement for both metallic plates and synthetic fibre reinforced composites. Potential of natural fibres for thermal load still needs a lot of studies. In this work, Flax/epoxy composite plate is prepared and numerical analysis on the thermal buckling of the composite plate is carried out using commercially available Finite Element Analysis software ANSYS Workbench. The design of experiment (DOE) approach is used to examine the buckling characteristics of the composite. The central composite design (CCD) methodology is used for the analysis. The variables considered in the DOE part are aspect ratio, ply orientation, and boundary conditions. Based on the DOE/ANOVA study, quadratic regression equation is developed which relates to the influence of these variables on the critical thermal buckling temperature of the flax/epoxy reinforced composite using Minitab Software.
{"title":"Thermal buckling of flax fibre reinforced epoxy laminated composite plate using finite element analysis","authors":"Guru Anandan, V. Gopalan, S. Natarajan","doi":"10.1080/15502287.2021.1948149","DOIUrl":"https://doi.org/10.1080/15502287.2021.1948149","url":null,"abstract":"Abstract Nowadays natural fibre reinforced composite plates are shown importance due to its eco-friendly nature. If natural fibre reinforced composite is manufactured properly, it will be a suitable replacement for both metallic plates and synthetic fibre reinforced composites. Potential of natural fibres for thermal load still needs a lot of studies. In this work, Flax/epoxy composite plate is prepared and numerical analysis on the thermal buckling of the composite plate is carried out using commercially available Finite Element Analysis software ANSYS Workbench. The design of experiment (DOE) approach is used to examine the buckling characteristics of the composite. The central composite design (CCD) methodology is used for the analysis. The variables considered in the DOE part are aspect ratio, ply orientation, and boundary conditions. Based on the DOE/ANOVA study, quadratic regression equation is developed which relates to the influence of these variables on the critical thermal buckling temperature of the flax/epoxy reinforced composite using Minitab Software.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124460152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-05DOI: 10.1080/15502287.2021.1946620
Mosfequr Rahman, J. C. Liggett, Kacie Grella, Benjamin Gagnon, Alejandro Membreno
Abstract In this research, a method is examined by which the behavior of continuous carbon fiber reinforced additive manufacturing may be simulated using Finite Element Analysis. This technique is used in a simulated tensile test experiment in which the findings are compared to results determined from theoretical calculations according to the Rule of Mixtures method and from existing mechanical testing results. Four different fiber reinforcement configurations are examined with fiber volume fractions ranging from 4% to 32%. It was found that for fiber volume fractions of 11%, the simulation results closely match those predicted theoretically by the Rule of Mixtures as well as the mechanical testing results published in existing research. Lower fiber volume fractions near 4% yield less accurate results, with a 20% error due to the fact that the anisotropic behavior of the polymer matrix is the dominant material trait. Simulation of higher volume fractions near 32% closely approximate theoretical predictions, however neither the theoretical results nor the simulation results accurately reflect real world mechanical testing, indicating that nonideal condition factors such as the effect of micro-voids between the start and end of the fiber reinforcements play a significant role in the overall strength of the material. Thus, for fiber volume fractions near 11%, this simulation method can accurately be used to predict the behavior of end-use components, but more study must be done to increase simulation accuracy in low and high fiber volume fractions.
{"title":"Validation of a finite element method for simulation of components produced by continuous carbon fiber reinforced additive manufacturing","authors":"Mosfequr Rahman, J. C. Liggett, Kacie Grella, Benjamin Gagnon, Alejandro Membreno","doi":"10.1080/15502287.2021.1946620","DOIUrl":"https://doi.org/10.1080/15502287.2021.1946620","url":null,"abstract":"Abstract In this research, a method is examined by which the behavior of continuous carbon fiber reinforced additive manufacturing may be simulated using Finite Element Analysis. This technique is used in a simulated tensile test experiment in which the findings are compared to results determined from theoretical calculations according to the Rule of Mixtures method and from existing mechanical testing results. Four different fiber reinforcement configurations are examined with fiber volume fractions ranging from 4% to 32%. It was found that for fiber volume fractions of 11%, the simulation results closely match those predicted theoretically by the Rule of Mixtures as well as the mechanical testing results published in existing research. Lower fiber volume fractions near 4% yield less accurate results, with a 20% error due to the fact that the anisotropic behavior of the polymer matrix is the dominant material trait. Simulation of higher volume fractions near 32% closely approximate theoretical predictions, however neither the theoretical results nor the simulation results accurately reflect real world mechanical testing, indicating that nonideal condition factors such as the effect of micro-voids between the start and end of the fiber reinforcements play a significant role in the overall strength of the material. Thus, for fiber volume fractions near 11%, this simulation method can accurately be used to predict the behavior of end-use components, but more study must be done to increase simulation accuracy in low and high fiber volume fractions.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"43 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115755913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-30DOI: 10.1080/15502287.2021.1941426
D. Pal, S. Mondal
Abstract The present paper deals with the analysis of entropy generation of the hydromagnetic stagnation-point flow of viscoelastic nanofluid past a stretching sheet with viscous-Ohmic dissipation, chemical reaction, and nonlinear thermal radiation in a porous medium. The governing equations are solved numerically by the spectral quasilinearization method (SQLM). The effect of different parameters on velocity, temperature, concentration, and entropy profiles are shown graphically. It is pointed out that the entropy profile increases for higher values of the thermal radiation parameter, temperature ratio parameter, Reynolds number, whereas the reverse effect is traced for the viscoelastic parameter on the entropy profile. The numerical results are compared under some special cases with the previously published results those are available in the literature and showed a very good agreement.
{"title":"Analysis of entropy generation on hydromagnetic viscoelastic nanofluid in stagnation-point flow over a stretching sheet","authors":"D. Pal, S. Mondal","doi":"10.1080/15502287.2021.1941426","DOIUrl":"https://doi.org/10.1080/15502287.2021.1941426","url":null,"abstract":"Abstract The present paper deals with the analysis of entropy generation of the hydromagnetic stagnation-point flow of viscoelastic nanofluid past a stretching sheet with viscous-Ohmic dissipation, chemical reaction, and nonlinear thermal radiation in a porous medium. The governing equations are solved numerically by the spectral quasilinearization method (SQLM). The effect of different parameters on velocity, temperature, concentration, and entropy profiles are shown graphically. It is pointed out that the entropy profile increases for higher values of the thermal radiation parameter, temperature ratio parameter, Reynolds number, whereas the reverse effect is traced for the viscoelastic parameter on the entropy profile. The numerical results are compared under some special cases with the previously published results those are available in the literature and showed a very good agreement.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117325633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-16DOI: 10.1080/15502287.2021.1916198
Jiahao Zhang, Junjun Zheng, H. Okamura, T. Dohi
Abstract Phase-type (PH) fitting is a technique to approximate any general distribution as a PH distribution, which is a probability distribution representing an absorbing time of a Markov chain. Since the PH distribution is described as a discrete- or continuous-time Markov chain (CTMC), the PH fitting can provide approximate Markov models to any non-exponential stochastic models. Thus, the PH fitting is helpful for model-based performance evaluation. On the other hand, from the statistical point of view, the PH fitting is categorized as parameter estimation from data. Some efficient PH fitting techniques are based on the maximum-likelihood principle. Therefore, it is crucial to evaluate statistical errors, i.e., the variance and covariance of estimators. In maximum-likelihood estimation, the Fisher information matrix is a well-known method to compute the variance and covariance of estimators, and is obtained as the second derivative of the log-likelihood function (LLF). In this article, we propose an algorithm for efficiently computing the Fisher information matrix in PH fitting. By applying the uniformization technique to a CTMC, we design the algorithm for computing the second derivatives of LLF in PH fitting.
{"title":"An efficient algorithm for computation of information matrix in phase-type fitting","authors":"Jiahao Zhang, Junjun Zheng, H. Okamura, T. Dohi","doi":"10.1080/15502287.2021.1916198","DOIUrl":"https://doi.org/10.1080/15502287.2021.1916198","url":null,"abstract":"Abstract Phase-type (PH) fitting is a technique to approximate any general distribution as a PH distribution, which is a probability distribution representing an absorbing time of a Markov chain. Since the PH distribution is described as a discrete- or continuous-time Markov chain (CTMC), the PH fitting can provide approximate Markov models to any non-exponential stochastic models. Thus, the PH fitting is helpful for model-based performance evaluation. On the other hand, from the statistical point of view, the PH fitting is categorized as parameter estimation from data. Some efficient PH fitting techniques are based on the maximum-likelihood principle. Therefore, it is crucial to evaluate statistical errors, i.e., the variance and covariance of estimators. In maximum-likelihood estimation, the Fisher information matrix is a well-known method to compute the variance and covariance of estimators, and is obtained as the second derivative of the log-likelihood function (LLF). In this article, we propose an algorithm for efficiently computing the Fisher information matrix in PH fitting. By applying the uniformization technique to a CTMC, we design the algorithm for computing the second derivatives of LLF in PH fitting.","PeriodicalId":315058,"journal":{"name":"International Journal for Computational Methods in Engineering Science and Mechanics","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126347023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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