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Book part
Publication date: 10 April 2006

Georgiy Levchuk, Daniel Serfaty and Krishna R. Pattipati

Over the past few years, mathematical and computational models of organizations have attracted a great deal of interest in various fields of scientific research (see Lin & Carley

Abstract

Over the past few years, mathematical and computational models of organizations have attracted a great deal of interest in various fields of scientific research (see Lin & Carley, 1993 for review). The mathematical models have focused on the problem of quantifying the structural (mis)match between organizations and their tasks. The notion of structural congruence has been generalized from the problem of optimizing distributed decision-making in structured decision networks (Pete, Pattipati, Levchuk, & Kleinman, 1998) to the multi-objective optimization problem of designing optimal organizational structures to complete a mission, while minimizing a set of criteria (Levchuk, Pattipati, Curry, & Shakeri, 1996, 1997, 1998). As computational models of decision-making in organizations began to emerge (see Carley & Svoboda, 1996; Carley, 1998; Vincke, 1992), the study of social networks (SSN) continued to focus on examining a network structure and its impact on individual, group, and organizational behavior (Wellman & Berkowitz, 1988). Most models, developed under the SSN, combined formal and informal structures when representing organizations as architectures (e.g., see Levitt et al., 1994; Carley & Svoboda, 1996). In addition, a large number of measures of structure and of the individual positions within the structure have been developed (Roberts, 1979; Scott, 1981; Wasserman & Faust, 1994; Wellman, 1991).

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Understanding Adaptability: A Prerequisite for Effective Performance within Complex Environments
Type: Book
ISBN: 978-1-84950-371-6

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Article
Publication date: 30 March 2010

Ahmet Yıldırım

This paper aims to present a general framework of the homotopy perturbation method (HPM) for analytic treatment of fractional partial differential equations in fluid mechanics…

878

Abstract

Purpose

This paper aims to present a general framework of the homotopy perturbation method (HPM) for analytic treatment of fractional partial differential equations in fluid mechanics. The fractional derivatives are described in the Caputo sense.

Design/methodology/approach

Numerical illustrations that include the fractional wave equation, fractional Burgers equation, fractional KdV equation and fractional Klein‐Gordon equation are investigated to show the pertinent features of the technique.

Findings

HPM is a powerful and efficient technique in finding exact and approximate solutions for fractional partial differential equations in fluid mechanics. The implementation of the noise terms, if they exist, is a powerful tool to accelerate the convergence of the solution. The results so obtained reinforce the conclusions made by many researchers that the efficiency of the HPM and related phenomena gives it much wider applicability.

Originality/value

The essential idea of this method is to introduce a homotopy parameter, say p, which takes values from 0 to 1. When p = 0, the system of equations usually reduces to a sufficiently simplied form, which normally admits a rather simple solution. As p is gradually increased to 1, the system goes through a sequence of deformations, the solution for each of which is close to that at the previous stage of deformation.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 2
Type: Research Article
ISSN: 0961-5539

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Available. Content available
Book part
Publication date: 21 January 2021

Alberto Tron

Free Access. Free Access

Abstract

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Corporate Financial Distress
Type: Book
ISBN: 978-1-83982-981-9

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Article
Publication date: 2 January 2025

Mohammad Farahbakhsh Kargosha, Abbasali Motallebi, Ebrahim Rahimi, Amir Shakerian and Hamidreza Kazemeini

This study aims to prepare probiotic sodium caseinate-gelatin films containing Lactobacillus paracasei, Bifidobacterium bifidum and Lactobacillus plantarum, and evaluate their…

7

Abstract

Purpose

This study aims to prepare probiotic sodium caseinate-gelatin films containing Lactobacillus paracasei, Bifidobacterium bifidum and Lactobacillus plantarum, and evaluate their application on the microbiological, chemical, mechanical and sensory properties of rainbow trout fillets during 12 days of refrigerated storage.

Design/methodology/approach

The physical, chemical and mechanical properties of the designed films were assessed. In addition, the rainbow trout fillets were examined for microbiological, chemical parameters and sensory attributes.

Findings

According to the results, a negative correlation was found between the survival of probiotic bacteria and the storage time of the films. The counts of L. paracasei, B. bifidum and L. plantarum showed a decreasing trend during the study, starting from (2.9, 3.9 and 1.9 log CFU/g, respectively) at day 0 and reaching (6.79, 5.84 and 6.14 log CFU/g, respectively) at the end of the study (day 12).

Originality/value

It was observed that the sodium caseinate-gelatin probiotic films delayed the microbial growth in rainbow trout fillets compared to the control group. Furthermore, significant differences in chemical changes were found in all treated fish fillets compared to the untreated group.

Details

Nutrition & Food Science, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0034-6659

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Article
Publication date: 2 November 2018

Majed Mokhtari, M. Shahravy and M. Zabihpoor

The purpose of this study is to focus on the developments of carbon fiber reinforced polymer (CFRP) panels with stepwise graded properties on adhesive layer. The various arranges…

134

Abstract

Purpose

The purpose of this study is to focus on the developments of carbon fiber reinforced polymer (CFRP) panels with stepwise graded properties on adhesive layer. The various arranges of the graded properties of the adhesive layer have been checked according to experimental results of the literatures and based on applicability.

Design/methodology/approach

The finite element (FE) models and experimental modal tests of the manufactured CFRP sandwich panel specimens have been investigated. The core thickness, core density and orientation of the fiber direction of the sandwich panel face – sheets have been parametrically checked based on modal behavior. Two fully free and fully clamped boundary conditions (BC) have been checked in stepwise graded adhesive zone (SGAZ) cases and first five non-zero natural frequencies (NF) have been compared. Dynamic response of the SGAZ includes modal analysis and transient dynamic loading have been performed numerically with ABAQUS 6.12 well-known FE code.

Findings

The first non-zero NF of SGAZ Case 4 was 11.69 per cent higher than homogenous Case 2 and 7.06 per cent lower than Case 1 in fully free boundary conditions. A total of 26.38 per cent is the greatest discrepancy between fist five non-zero NFs of all cases with two BCs (Case 1 vs Case 2 in fully clamped BC). Maximum structural damping behavior and minimum stress picks have been studied during transient dynamic loading analysis of CFRP panel with SGAZ. SGAZ Case 3 (middle adhesive with lower modulus) has increased the maximum structural damping while reducing the minimum out of plain tip displacements during transient dynamic loading by 111.26 per cent in comparison with homogenous Case 2. Also, Case 3 has reduced the Mises stress picks on the adhesive region by 605.68 per cent.

Practical implications

Making a stepwise graded adhesive region (without any added mass) has been shown that it is a novel and useful way to achieve a wide range of stiffness on CFRP panels.

Originality/value

Development of the sandwich panels with various stiffness and damping properties.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 1
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 1 January 2012

Izzet Cagdas and Sarp Adali

The purpose of this paper is to present the optimal design of a simply supported variable curvature laminated angle-ply composite panel under uniaxial compression. The objective…

229

Abstract

Purpose

The purpose of this paper is to present the optimal design of a simply supported variable curvature laminated angle-ply composite panel under uniaxial compression. The objective is to maximize the failure load which is defined as the minimum of the buckling load and the first-ply failure load.

Design/methodology/approach

The numerical results presented are obtained using a shear deformable degenerated shell finite element, a brief formulation of which is given. Some verification problems are solved and a convergence study is conducted in order to assess the accuracy of the element. The design procedure is presented and optimization results are given for a simply supported symmetric eight layer angle-ply panel composed of a flat and two cylindrical sections.

Findings

The influences of the stacking sequence and panel thickness on optimization are investigated and the effects of various problem parameters on the optimization procedure are discussed.

Originality/value

The paper shows that the load carrying capacity of thicker panels is considerably reduced when the first-ply failure constraint is taken into account.

Details

Engineering Computations: International Journal for Computer-Aided Engineering and Software, vol. 29 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 8 June 2012

Mehdi Dehghan and Jalil Manafian Heris

This paper aims to show that the variational iteration method (VIM) and the homotopy perturbation method (HPM) are powerful and suitable methods to solve the Fornberg‐Whitham…

175

Abstract

Purpose

This paper aims to show that the variational iteration method (VIM) and the homotopy perturbation method (HPM) are powerful and suitable methods to solve the Fornberg‐Whitham equation.

Design/methodology/approach

Using HPM the explicit exact solution is calculated in the form of a quickly convergent series with easily computable components. Also, by using VIM the analytical results of this equation have been obtained in terms of convergent series with easily computable components.

Findings

Numerical solutions obtained by these methods are compared with the exact solutions, revealing that the obtained solutions are of high accuracy.

Originality/value

Also the results show that the introduced methods are efficient tools for solving the nonlinear partial differential equations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 3 August 2012

Mehdi Dehghan, Jalil Manafian and Abbas Saadatmandi

Rosenau‐Hyman equation was discovered as a simplified model to study the role of nonlinear dispersion on pattern formation in liquid drops. Also, this equation has important roles…

267

Abstract

Purpose

Rosenau‐Hyman equation was discovered as a simplified model to study the role of nonlinear dispersion on pattern formation in liquid drops. Also, this equation has important roles in the modelling of various problems in physics and engineering. The purpose of this paper is to present the solution of Rosenau‐Hyman equation.

Design/methodology/approach

This paper aims to present the solution of the Rosenau‐Hyman equation by means of semi‐analytical approaches which are based on the homotopy perturbation method (HPM), variational iteration method (VIM) and Adomian decomposition method (ADM).

Findings

These techniques reduce the volume of calculations by not requiring discretization of the variables, linearization or small perturbations. Numerical solutions obtained by these methods are compared with the exact solutions, revealing that the obtained solutions are of high accuracy. These results reveal that the proposed methods are very effective and simple to perform.

Originality/value

Efficient techniques are developed to find the solution of an important equation.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

Available. Open Access. Open Access
Article
Publication date: 21 June 2021

Mushtaq Ali, Mohammed Almoaeet and Basim Karim Albuohimad

This study aims to use new formula derived based on the shifted Jacobi functions have been defined and some theorems of the left- and right-sided fractional derivative for them…

818

Abstract

Purpose

This study aims to use new formula derived based on the shifted Jacobi functions have been defined and some theorems of the left- and right-sided fractional derivative for them have been presented.

Design/methodology/approach

In this article, the authors apply the method of lines (MOL) together with the pseudospectral method for solving space-time partial differential equations with space left- and right-sided fractional derivative (SFPDEs). Then, using the collocation nodes to reduce the SFPDEs to the system of ordinary differential equations, which can be solved by the ode45 MATLAB toolbox.

Findings

Applying the MOL method together with the pseudospectral discretization method converts the space-dependent on fractional partial differential equations to the system of ordinary differential equations.

Originality/value

This paper contributes to gain choosing the shifted Jacobi functions basis with special parameters a, b and give the authors this opportunity to obtain the left- and right-sided fractional differentiation matrices for this basis exactly. The results of the examples are presented in this article. The authors found that the method is efficient and provides accurate results, and the authors found significant implications for success in the science, technology, engineering and mathematics domain.

Details

Arab Journal of Mathematical Sciences, vol. 28 no. 2
Type: Research Article
ISSN: 1319-5166

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Article
Publication date: 20 September 2011

Mehdi Dehghan and Fatemeh Shakeri

Multi‐point boundary value problems have important roles in the modelling of various problems in physics and engineering. This paper aims to present the solution of ordinary…

481

Abstract

Purpose

Multi‐point boundary value problems have important roles in the modelling of various problems in physics and engineering. This paper aims to present the solution of ordinary differential equations with multi‐point boundary value conditions by means of a semi‐numerical approach which is based on the homotopy analysis method.

Design/methodology/approach

The convergence of the obtained solution is expressed and some typical examples are employed to illustrate validity, effectiveness and flexibility of this procedure. This approach, in contrast to perturbation techniques, is valid even for systems without any small/large parameters and therefore it can be applied more widely than perturbation techniques, especially when there do not exist any small/large quantities.

Findings

Unlike other analytic techniques, this approach provides a convenient way to adjust and control the convergence of approximation series. Some applications will be briefly introduced.

Originality/value

The paper shows how an important boundary value problem is solved with a semi‐analytical method.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 21 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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