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Article
Publication date: 23 November 2018

Sara Yousefi, Reza Farzipoor Saen and Seyed Shahrooz Seyedi Hosseininia

To manage cash flow in supply chains, the purpose of this paper is to propose inverse data envelopment analysis (DEA) model.

Abstract

Purpose

To manage cash flow in supply chains, the purpose of this paper is to propose inverse data envelopment analysis (DEA) model.

Design/methodology/approach

This paper develops an inverse range directional measure (RDM) model to deal with positive and negative values. The proposed model is developed to estimate input and output variations such that not only efficiency score of decision making unit (DMU) remains unchanged, but also efficiency score of other DMUs do not change.

Findings

Given that auto making industry deals with huge variety and volumes of parts, cash flow management is so important. In this paper, inverse RDM models are developed to manage cash flow in supply chains. For the first time, the authors propose inverse DEA models to deal with negative data. By applying the inverse DEA models, managers distinguish efficient DMUs from inefficient ones and devise appropriate strategies to increase efficiency score. Given results of inverse integrated RDM model, other combinations of cash flow strategies are proposed. The suggested strategies can be taken into account as novel strategies in cash flow management. Interesting point is that such strategies do not lead to changes in efficiency scores.

Originality/value

In this paper, inverse input and output-oriented RDM model is developed in presence of negative data. These models are applied in resource allocation and investment analysis problems. Also, inverse integrated RDM model is developed.

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Article
Publication date: 1 June 1999

Mohamed S. Gadala and Andrew D.B. McCullough

This paper presents a numerical study of inverse parameter identification problems in fracture mechanics. Inverse methodology is applied to the detection of subsurface…

Abstract

This paper presents a numerical study of inverse parameter identification problems in fracture mechanics. Inverse methodology is applied to the detection of subsurface cracks and to the study of propagating cracks. The procedure for detecting subsurface cracks combines the finite element method with a sequential quadratic programming algorithm to solve for the unknown geometric parameters associated with the internal flaw. The procedure utilizes finite element substructuring capabilities in order to minimize the processing and solution time for practical problems. The finite element method and non‐linear optimization are also used in determining the direction a crack will propagate in a heterogeneous planar domain. This procedure involves determining the direction that produces the maximum strain energy release for a given increment of crack growth. The procedure is applied to several numerical examples. The results of these numerical studies coincide with theoretical predictions and experimentally observed crack behavior.

Details

Engineering Computations, vol. 16 no. 4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 7 March 2016

Joanna E. Laszczyk and Andrzej J Nowak

The purpose of this paper is to present the computational model of the neonate’s brain cooling process. The main aim of the analysis is to tune the developed computational…

Abstract

Purpose

The purpose of this paper is to present the computational model of the neonate’s brain cooling process. The main aim of the analysis is to tune the developed computational model, make it convergent and representing the hypothermia therapy reasonably. To find the appropriate model parameters the trial of an inverse analysis, based on the standard least-square method, is performed. Having partially validated model the number of numerical simulations are carried out to compare their results with measurements made during real therapy.

Design Methodology Approach

The geometrical model of the newborn’s body is built using MRI and CT scans utilizing Mimics software and the Design Modeler while Ansys Fluent with its User Defined Function capability was used to implement the whole model and to carry out simulations. To model the bioheat transfer the Pennes bioheat equation is applied. In the mathematical model blood perfusion rate, metabolic heat generation rate as well as the arterial blood temperature are dependent on the tissue temperature. In order to determine the proper values of model parameters of bioheat transport in neonate’s body the attempt to inverse analysis is also performed.

Findings

The performed inverse analysis resulted in the values of model parameters (metabolic heat sources, blood perfusions etc.). Tuned model was then applied to simulate brain cooling process with reasonable accuracy. Obtained model parameters were also compared to the data obtained from neonatologists.

Research limitations implications

The presented numerical model still requires tests and simulations. The results from the inverse analysis based on the real measurements can be very valuable.

Practical implications

The determination of the proper parameters of the bioheat transfer in the neonatal body can finally be used to control the numerical simulations of the brain cooling process. The simulation of the re-warming process after hypothermic therapy can be improved considerably.

Social implications

The performance of the numerical simulations of the brain cooling process in the proper way can finally helps protect newborns’ health and life.

Originality Value

In the paper 3-D real geometrical model of the newborn’s body includes head, torso and limbs and different types of tissues are distinguished in the model. The considered bioheat transfer problem is also fully 3-D. This model is then utilised together with inverse analysis in order to determine the model parameters for the newborn’s body.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 13 June 2016

Lei Wang, Xiaojun Wang and Xiao Li

– The purpose of this paper is to focus on the influences of the uncertain dynamic responses on the reconstruction of loads.

Abstract

Purpose

The purpose of this paper is to focus on the influences of the uncertain dynamic responses on the reconstruction of loads.

Design/methodology/approach

Based on the assumption of unknown-but-bounded (UBB) noise, a time-domain approach to estimate the uncertain time-dependent external loads is presented by combining the inverse system method in modern control theory and interval analysis in interval mathematics. Inspired by the concept of set membership identification in control theory, an interval analysis model of external loads time history, which is indeed a region or feasible set containing all possible loads being consistent with the bounded structural acceleration responses is established and further solved by two interval algorithms.

Findings

Unlike traditional loads identification methods which only give a point estimation, an interval estimation of external loads time history, which is a region containing all the possible loads being consistent with the uncertain structural responses, is determined. The correlation characteristics among the responses of acceleration, velocity, and displacement are also discussed in consideration of the UBB uncertainty.

Originality/value

For one hand, the solution of the inverse problem in original system is transformed to the solution of the direct problem in inverse system; for another, the authors deal with the uncertainty by use of interval analysis method, and the identified interval process, which contains any possible external loads time history being consistent with the bounded structural responses can be approximately obtained.

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Article
Publication date: 26 September 2019

Peyman Mayeli and Mehdi Nikfar

The present study aims to perform inverse analysis of a conjugate heat transfer problem including conduction and forced convection via the quasi-Newton method. The inverse

Abstract

Purpose

The present study aims to perform inverse analysis of a conjugate heat transfer problem including conduction and forced convection via the quasi-Newton method. The inverse analysis is defined for a heat source that is surrounded by a solid medium which is exposed to a free stream in external flow.

Design/methodology/approach

The objective of the inverse design problem is finding temperature distribution of the heat source as thermal boundary condition to establish a prescribed temperature along the interface of solid body and fluid. This problem is a simplified version of thermal-based ice protection systems in which the formation of ice is avoided by maintaining the interface of fluid and solid at a specified temperature.

Findings

The effects of the different pertinent parameters such as Reynolds number, interface temperature and thermal conductivity ratio of fluid and solid mediums are analyzed.

Originality/value

This paper fulfils the analysis to study how thermal based anti-icing system can be used with different heat source shapes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 10
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 March 1996

Jean‐Loup Chenot, E. Massoni and JL. Fourment

Focuses on the inverse problems arising from the simulation of forming processes. Considers two sets of problems: parameter identification and shape optimization. Both are…

Abstract

Focuses on the inverse problems arising from the simulation of forming processes. Considers two sets of problems: parameter identification and shape optimization. Both are solved using an optimization method for the minimization of a suitable objective function. The convergence and convergence rate of the method depend on the accuracy of the derivatives of this function. The sensitivity analysis is based on a discrete approach, e.g. the differentiation of the discrete problem equations. Describes the method for non‐linear, non‐steady‐state‐forming problems involving contact evolution. First, it is applied to the parameter identification and to the torsion test. It shows good convergence properties and proves to be very efficient for the identification of the material behaviour. Then, it is applied to the tool shape optimization in forging for a two‐step process. A few iterations of the inverse method make it possible to suggest a suitable shape for the preforming tools.

Details

Engineering Computations, vol. 13 no. 2/3/4
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 1 March 2002

Hamdy Mohy Afefy, Salah El‐Din Fahmy Taher, Abdel‐Hakim A. Khalil and Mohamed E. Issa

The most simple equivalent frame system with reduced degrees of freedom is proposed for handling multi‐story multi‐bay infilled frames. The system is composed of…

Abstract

The most simple equivalent frame system with reduced degrees of freedom is proposed for handling multi‐story multi‐bay infilled frames. The system is composed of homogenized continuum for the reinforced concrete members braced with unilateral diagonal struts for each bay, which are only activated in compression. Identification of the equivalent system characteristics and nonlinear material properties are accomplished from the concepts of inverse analysis approach along with statistical tests of hypotheses is employed to establish the appropriate filtering scheme and the proper accuracy tolerance. The suggested system allows for nonlinear finite element static and dynamic analysis of sophisticated infilled reinforced concrete frames. Sensitivity analysis is undertaken to check the suitability of the proposed system to manipulate various structural applications.

Details

Engineering Computations, vol. 19 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 August 2003

Iwona Nowak, Andrzej J. Nowak and Luiz C. Wrobel

This paper discusses an algorithm for phase change front identification in continuous casting. The problem is formulated as an inverse geometry problem, and the solution…

Abstract

This paper discusses an algorithm for phase change front identification in continuous casting. The problem is formulated as an inverse geometry problem, and the solution procedure utilizes temperature measurements inside the solid phase and sensitivity coefficients. The proposed algorithms make use of the boundary element method, with cubic boundary elements and Bezier splines employed for modelling the interface between the solid and liquid phases. A case study of continuous casting of copper is solved to demonstrate the main features of the proposed algorithms.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 13 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 27 March 2008

H. Ahmadi‐Noubari, A. Pourshaghaghy, F. Kowsary and A. Hakkaki‐Fard

The purpose of this paper is to reduce the destructive effects of existing unavoidable noises contaminating temperature data in inverse heat conduction problems (IHCP…

Abstract

Purpose

The purpose of this paper is to reduce the destructive effects of existing unavoidable noises contaminating temperature data in inverse heat conduction problems (IHCP) utilizing the wavelets.

Design/methodology/approach

For noise reduction, sensor data were treated as input to the filter bank used for signal decomposition and implementation of discrete wavelet transform. This is followed by the application of wavelet denoising algorithm that is applied on the wavelet coefficients of signal components at different resolution levels. Both noisy and de‐noised measurement temperatures are then used as input data to a numerical experiment of IHCP. The inverse problem deals with an estimation of unknown surface heat flux in a 2D slab and is solved by the variable metric method.

Findings

Comparison of estimated heat fluxes obtained using denoised data with those using original sensor data indicates that noise reduction by wavelet has a potential to be a powerful tool for improvement of IHCP results.

Originality/value

Noise reduction using wavelets, while it can be implemented very easily, may also significantly relegate (or even eliminate) conventional regularization schemes commonly used in IHCP.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 17 July 2019

Hua Li and Lufeng Jia

The purpose of this paper is to propose a numerical approaching analysis method combining the sequential unconstrained minimization technique and finite element method to…

Abstract

Purpose

The purpose of this paper is to propose a numerical approaching analysis method combining the sequential unconstrained minimization technique and finite element method to identify the loading condition and geometry of smart structures accurately.

Design/methodology/approach

A new load identification model is built and the finite element approaching method is proposed by the combination of finite element method and optimization technique.

Findings

The approaching algorithm has good convergence and fast approximation speed; the accuracy can meet the engineering requirements. The approaching model is simple, and the precision is controllable and it can be used to solve the load identification problem of the smart material structure.

Originality/value

In view of the cited papers, the information sensed by the smart structure is limited, discrete and contains certain errors. How to derive the cause from the limited, error-containing discrete information is an important problem that needs to be solved by the self-diagnosis function. A load identification model based on structural displacement response is established and a numerical approximation method is proposed by combining the finite element method with the optimization technique; the load magnitude and position of the structure are identified according to the displacement measurement values of the internal finite point in the structure under the load condition.

Details

International Journal of Structural Integrity, vol. 11 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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