Description of Osmotic Dehydration of Melon Cubes using a Three-dimensional Diffusion Model: An Algorithm to Determine the Effective Diffusivity

2017 ◽  
Vol 13 (12) ◽  
Author(s):  
Rubens Maciel Miranda Pinheiro ◽  
Wilton Pereira da Silva ◽  
Denise Silva do Amaral Miranda ◽  
Cleide M. D. P. S. e Silva ◽  
Taciano Pessoa ◽  
...  
Keyword(s):  
Experimental Data ◽  
Objective Function ◽  
Effective Mass ◽  
Osmotic Dehydration ◽  
Three Dimensional ◽  
Effective Diffusivity ◽  
Chi Square ◽  
Minimum Value ◽  
Mass Diffusivity ◽  
Optimal Value

AbstractThis paper aims to study the transient mass diffusion during the osmotic dehydration of melon cubes, using the analytical solution of the diffusion equation with boundary condition of the first kind. Two techniques are used to determine the effective mass diffusivity, using experimental data. In technique 1, available in the literature, the domain of the effective diffusivity is scanned from a value close to zero, until the minimum value of the objective function (Chi-square) is determined. Technique 2, proposed in this paper, uses an algorithm based on the optimal removal of experimental points, until obtaining the objective function with a minimum value, allowing to determine the optimal value for the effective mass diffusivity. The obtained values for diffusivity and statistical indicators revealed that both techniques generate equivalent results and allowed to satisfactorily describe the kinetics of osmotic dehydration of melon cubes. However, technique 2, proposed in this paper, is much faster than technique 1, in the determination of effective mass diffusivity, for all analyzed sets of experimental data.

scholarly journals Drying kinetics of crushed mass of ‘jambu’: Effective diffusivity and activation energy

2018 ◽  
Vol 22 (7) ◽  
pp. 499-505 ◽  
Author(s):  
Francileni P. Gomes ◽  
Resende Osvaldo ◽  
Elisabete P. Sousa ◽  
Daneil E. C. de Oliveira ◽  
Francisco R. de Araújo Neto
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Agricultural Research ◽  
Effective Diffusion ◽  
Effective Diffusivity ◽  
Information Criterion ◽  
Drying Kinetics ◽  
Coefficient Of Determination ◽  
Chi Square ◽  
Chi Square Test

ABSTRACT The aim of this paper was to analyze the drying kinetics, test the Akaike information criterion (AIC) and Schwarz’s Bayesian information criterion (BIC) in the selection of models, determine the effective diffusivity and activation energy of the crushed mass of ‘jambu’ leaves for different conditions of temperature and layer thicknesses. The experiment was carried out at the Food Laboratory of the Brazilian Agricultural Research Corporation (Embrapa) in Macapá-AP. Drying was carried out in air circulation oven with speed of 1.0 m s-1 at various temperatures (60, 70 and 80 ºC) and layer thicknesses (0.005 and 0.010 m). The experimental data were fitted to 11 mathematical models. Coefficient of determination (R2), mean relative error (P), mean estimated error (SE), Chi-square test (χ2), AIC and BIC were the selection criteria for the models. For the effective diffusivity, the Fick’s diffusion model was used considering the flat plate geometry. It was found that Midilli and Logarithmic models showed the best fit to the experimental data of drying kinetics. Effective diffusion coefficient increases with increment in the thickness of the material and with the temperature elevation. Activation energy of the material was of 16.61 kJ mol-1 for the thickness of 0.005 m, and 16.97 kJ mol-1 for the thickness of 0.010 m. AIC and BIC can be additionally included to select models of drying.

scholarly journals Thin Layer Drying Kinetics Modelling of Curry Leaves (Murraya koenigii L.) in Cabinet Dryer

2018 ◽  
Vol 2 ◽  
pp. 53-58
Author(s):  
Arjun Ghimire ◽  
Nirajan Magar
Keyword(s):  
Experimental Data ◽  
Thin Layer ◽  
Effective Diffusivity ◽  
Coefficient Of Determination ◽  
Murraya Koenigii ◽  
Small Tree ◽  
Chi Square ◽  
Kinetics Modelling ◽  
Curry Leaves ◽  
Thin Layer Drying

Curry leaves (Murraya koenigii L.) are the sweet smelling leaves of small tree of Rutaceae family native to Southwest Asia. In this study, the effect of temperatures (50, 55 and 60°C) on the drying of curry leaves was investigated. The experimental data were fitted to six thin layer mathematical models (Newton, Page, Handerson and Pabis, logarithmic, two-term exponential and Midilli et al). The models were evaluated in terms of coefficient of determination (R2), chi square (χ2) and root mean square error (RMSE). The Midilli et al model was best fitted to the experimental data of all the models evaluated. The effective diffusivity was calculated using Fick's diffusion equation, and the value varied from 2.07×10-12 m2/s to 2.643×10-12 m2/s. The activation energy and the diffusivity constant were found to be 21.808 kJ/mol and 4.667×10-8 m2/s respectively.

A Lattice Boltzmann Model of Calculating Mass Diffusivity in Nanofluids

2011 ◽  
Vol 391-392 ◽  
pp. 95-99 ◽  
Author(s):  
Zhong Li Tang ◽  
Bo Zhan
Keyword(s):  
Experimental Data ◽  
Effective Mass ◽  
Rhodamine B ◽  
Lattice Boltzmann ◽  
Diffusion Processes ◽  
Lattice Boltzmann Model ◽  
Volume Fractions ◽  
Mass Diffusivity ◽  
Boltzmann Model

So far, there were few models which could calculate the effective mass diffusivity De in nanofluids. In this paper, we proposed a lattice Boltzmann model to simulate the diffusion processes of Rhodamine B in 25nm-Cu/water nanofluids with different volume fractions and temperatures, and also calculated the effective mass diffusivity De. The results agreed well with the experimental data in literatures. So this model can be utilized to calculate the mass diffusivity in nanofluids. At last, we have discussed the enhancement mechanisms of diffusion in nanofluids.

scholarly journals Description of Guava Osmotic Dehydration Using a Three-Dimensional Analytical Diffusion Model

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Wilton Pereira da Silva ◽  
Cleide M. D. P. S. e Silva ◽  
Kalina Lígia Cavalcante de Almeida Farias Aires
Keyword(s):  
Effective Mass ◽  
Diffusion Model ◽  
Inverse Method ◽  
Osmotic Dehydration ◽  
Three Dimensional ◽  
Mass Distributions ◽  
Dimensional Diffusion ◽  
Proposed Model ◽  
Two Temperatures ◽  
Kinetics Of

The mass migrations during osmotic dehydration of guava were studied. Parallelepiped shaped slices were dipping in syrup of distilled water and sucrose with two concentrations and two temperatures. It was supposed that a three-dimensional diffusion model with boundary condition of the first kind satisfactorily describes the mass migrations and that the volume and effective mass diffusivities can be assumed constant during the process. The effective mass diffusivities were determined by coupling the three-dimensional analytical solution of the diffusion equation with an optimizer based on the inverse method. The proposed model well described the kinetics of water and sucrose migrations and enabled determining the mass distributions (water and sucrose) within the product at any instant.

scholarly journals Numerical description of guava osmotic dehydration including shrinkage and variable effective mass diffusivity

LWT ◽  
2014 ◽  
Vol 59 (2) ◽  
pp. 859-866 ◽  
Author(s):  
Wilton Pereira da Silva ◽  
Juarez Everton de Farias Aires ◽  
Deise Souza de Castro ◽  
Cleide Maria Diniz Pereira da Silva e Silva ◽  
Josivanda Palmeira Gomes
Keyword(s):  
Effective Mass ◽  
Osmotic Dehydration ◽  
Mass Diffusivity

Three-dimensional numerical analysis of water transfer in wood: determination of an expression for the effective mass diffusivity

2013 ◽  
Vol 47 (5) ◽  
pp. 897-912 ◽  
Author(s):  
Wilton Pereira da Silva ◽  
Laerson Duarte da Silva ◽  
Vera Solange de Oliveira Farias ◽  
Cleide Maria Diniz Pereira da Silva e Silva ◽  
Jair Stefanini Pereira de Ataíde
Keyword(s):  
Numerical Analysis ◽  
Effective Mass ◽  
Three Dimensional ◽  
Water Transfer ◽  
Mass Diffusivity

Guava Osmotic Dehydration: Description by Two-Dimensional Diffusion Models Considering Shrinkage and Variations in Process Parameters

2016 ◽  
Vol 12 (6) ◽  
pp. 527-536 ◽  
Author(s):  
Juarez Everton de Farias Aires ◽  
Wilton Pereira da Silva ◽  
Kalina Lígia Cavalcante de Almeida Farias Aires ◽  
Aluízio Freire da Silva Júnior ◽  
Deise Souza de Castro ◽  
...  
Keyword(s):  
Effective Mass ◽  
Process Parameters ◽  
Process Model ◽  
Numerical Solutions ◽  
Osmotic Dehydration ◽  
Parameters Estimation ◽  
Two Dimensional ◽  
One Dimensional ◽  
Mass Diffusivity ◽  
Dimensional Models

Abstract This article describes the osmotic dehydration of guava dipped in sucrose solutions using two-dimensional numerical solutions of the diffusion equation with boundary condition of the first kind. Two models are used: model 1 disregards the shrinkage of the product and assumes that effective mass diffusivity does not vary during the process; model 2 takes into account shrinkage, considering effective mass diffusivity as variable. Process parameters estimation is obtained by means of an optimizer. Comparative analyzes indicate that the proposed models have similar statistical indicators. However, model 2 is recommended, for it presents much higher physical fitness when describing mass migrations. Comparison between two-dimensional numerical models presented in this research and one-dimensional models found in the literature reveals that one-dimensional models overestimate process parameters. In addition, one-dimensional models present limitations in predicting the distributions of water and sucrose on guava slices.

scholarly journals Nitrogen-Doped Graphene Iron-Based Particle Electrode Outperforms Activated Carbon in Three-Dimensional Electrochemical Water Treatment Systems

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3121
Author(s):  
Hosna Ghanbarlou ◽  
Nikoline Loklindt Pedersen ◽  
Morten Enggrob Simonsen ◽  
Jens Muff
Keyword(s):  
Activated Carbon ◽  
Three Dimensional ◽  
Cell Voltage ◽  
Reduction Reaction ◽  
Process Data ◽  
Nitrogen Doped ◽  
Pesticide Removal ◽  
Optimal Value ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

The synergy between electrochemical oxidation and adsorption on particle electrodes was investigated in three-dimensional (3D) systems for p-nitrosodimethylaniline (RNO) decolorization and pesticide removal. A comparison was made between granular activated carbon (GAC) and a novel synthesized nitrogen-doped graphene-based particle electrode (NCPE). Experiments on RNO decolorization show that the synergy parameter of the 3D-NCPE system was improved 3000 times compared to the studied 3D-GAC system. This was due to the specific nanostructure and composition of the NCPE material. Nitrogen-doped graphene triggered an oxygen reduction reaction, producing hydrogen peroxide that simultaneously catalyzed on iron sites of the NCPEs to hydroxyl radicals following the electro-Fenton (EF) process. Data showed that in the experimental setup used for the study, the applied cell voltage required for the optimal value of the synergy parameter could be lowered to 5V in the 3D-NCPEs process, which is significantly better than the 15–20 V needed for synergy to be found in the 3D-GAC process. Compared to previous studies with 3D-GAC, the removal of pesticides 2,6 dichlorobenzamide (BAM), 2-methyl-4-chlorophenoxyaceticacid (MCPA), and methylchlorophenoxypropionic acid (MCPP) was also enhanced in the 3D-NCPE system.

scholarly journals An alternative perspective on copositive and convex relaxations of nonconvex quadratic programs

2021 ◽  
Author(s):  
E. Alper Yıldırım
Keyword(s):  
Objective Function ◽  
Convex Relaxation ◽  
Large Family ◽  
Quadratic Program ◽  
Feasible Region ◽  
Recession Cone ◽  
Convex Relaxations ◽  
Quadratic Programs ◽  
Alternative Perspective ◽  
Optimal Value

AbstractWe study convex relaxations of nonconvex quadratic programs. We identify a family of so-called feasibility preserving convex relaxations, which includes the well-known copositive and doubly nonnegative relaxations, with the property that the convex relaxation is feasible if and only if the nonconvex quadratic program is feasible. We observe that each convex relaxation in this family implicitly induces a convex underestimator of the objective function on the feasible region of the quadratic program. This alternative perspective on convex relaxations enables us to establish several useful properties of the corresponding convex underestimators. In particular, if the recession cone of the feasible region of the quadratic program does not contain any directions of negative curvature, we show that the convex underestimator arising from the copositive relaxation is precisely the convex envelope of the objective function of the quadratic program, strengthening Burer’s well-known result on the exactness of the copositive relaxation in the case of nonconvex quadratic programs. We also present an algorithmic recipe for constructing instances of quadratic programs with a finite optimal value but an unbounded relaxation for a rather large family of convex relaxations including the doubly nonnegative relaxation.

Three-dimensional asymmetric maximum weight lifting prediction considering dynamic joint strength

2021 ◽  
pp. 095441192098703
Author(s):  
Rahid Zaman ◽  
Yujiang Xiang ◽  
Jazmin Cruz ◽  
James Yang
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Three Dimensional ◽  
Optimization Method ◽  
Weight Lifting ◽  
Joint Torque ◽  
Maximum Weight ◽  
Angular Velocities ◽  
Asymmetric Lifting

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine joints. The 3D model has 40 degrees of freedom (DOFs) including 34 physical revolute joints and 6 global joints. A multi-objective optimization (MOO) problem is solved by simultaneously maximizing box weight and minimizing the sum of joint torque squares. A total of 12 male subjects were recruited to conduct maximum weight box lifting using squat-lifting strategy. Finally, the predicted lifting motion, ground reaction forces, and maximum lifting weight are validated with the experimental data. The prediction results agree well with the experimental data and the model’s predictive capability is demonstrated. This is the first study that uses MOO to predict maximum lifting weight and 3D asymmetric lifting motion while considering dynamic joint torque limits. The proposed method has the potential to prevent individuals’ risk of injury for lifting.

Sign in / Sign up

Export Citation Format

Share Document