Search results

1 – 10 of 16
To view the access options for this content please click here
Article

M. Poursina, C.A.C. António, C.F. Castro, J. Parvizian and L.C. Sousa

A numerical method for shape optimisation in forging is presented. The goal of the optimisation is to eliminate work‐piece defects that may arise during the forging…

Abstract

A numerical method for shape optimisation in forging is presented. The goal of the optimisation is to eliminate work‐piece defects that may arise during the forging process. A two‐dimensional finite element code has been developed for the simulation of the mechanical process. The material is incompressible and it follows the Norton‐Hoff law. To deal with contact constraint the velocity projection algorithm is used. The optimisation process is conducted using a genetic algorithm supported by an elitist strategy. A new genetic operator called adaptive mutation has been developed to increase the efficiency of the search. The developed scheme is used to design optimal preform shapes for several axisymmetric examples. Continuous and discrete design variables are considered. The objective function of the optimisation problem is associated with the quality of the final product. Comparing the obtained optimal results with the literature validates the proposed optimisation method.

Details

Engineering Computations, vol. 21 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article

Lorena Leocádio Gomes, Felicio Bruzzi Barros, Samuel Silva Penna and Roque Luiz da Silva Pitangueira

The purpose of this paper is to evaluate the capabilities of the generalized finite element method (GFEM) under the context of the geometrically nonlinear analysis. The…

Abstract

Purpose

The purpose of this paper is to evaluate the capabilities of the generalized finite element method (GFEM) under the context of the geometrically nonlinear analysis. The effect of large displacements and deformations, typical of such analysis, induces a significant distortion of the element mesh, penalizing the quality of the standard finite element method approximation. The main concern here is to identify how the enrichment strategy from GFEM, that usually makes this method less susceptible to the mesh distortion, may be used under the total and updated Lagrangian formulations.

Design/methodology/approach

An existing computational environment that allows linear and nonlinear analysis, has been used to implement the analysis with geometric nonlinearity by GFEM, using different polynomial enrichments.

Findings

The geometrically nonlinear analysis using total and updated Lagrangian formulations are considered in GFEM. Classical problems are numerically simulated and the accuracy and robustness of the GFEM are highlighted.

Originality/value

This study shows a novel study about GFEM analysis using a complete polynomial space to enrich the approximation of the geometrically nonlinear analysis adopting the total and updated Lagrangian formulations. This strategy guarantees the good precision of the analysis for higher level of mesh distortion in the case of the total Lagrangian formulation. On the other hand, in the updated Lagrangian approach, the need of updating the degrees of freedom during the incremental and iterative solution are for the first time identified and discussed here.

To view the access options for this content please click here
Article

Yang Liu, Zuyu Li, Peng Wei and Shikui Chen

The purpose of this paper is to explore the possibility of combining additive manufacturing (AM) with topology optimization to generate support structures for addressing…

Abstract

Purpose

The purpose of this paper is to explore the possibility of combining additive manufacturing (AM) with topology optimization to generate support structures for addressing the challenging overhang problem. The overhang problem is considered as a constraint, and a novel algorithm based on continuum topology optimization is proposed.

Design/methodology/approach

A mathematical model is formulated, and the overhang constraint is embedded implicitly through a Heaviside function projection. The algorithm is based on the Solid Isotropic Material Penalization (SIMP) method, and the optimization problem is solved through sensitivity analysis.

Findings

The overhang problem of the support structures is fixed. The optimal topology of the support structures is developed from a mechanical perspective and remains stable as the material volume of support structures changes, which allows engineers to adjust the material volume to save cost and printing time and meanwhile ensure sufficient stiffness of the support structures. Three types of load conditions for practical application are considered. By discussing the uniform distributive load condition, a compromise result is achieved. By discussing the point load condition, the removal work of support structures after printing is alleviated. By discussing the most unfavorable load condition, the worst collapse situation of the printing model during printing process is sufficiently considered. Numerical examples show feasibility and effectiveness of the algorithm.

Research limitations/implications

The proposed algorithm involves time-consuming finite element analysis and iterative solution, which increase the computation burden. Only the overhang constraint and the minimum compliance problem are discussed, while other constraints and objective functions may be of interest.

Practical implications

Compared with most of the existing heuristic or geometry-based support-generating algorithms, the proposed algorithm develops support structures for AM from a mechanical perspective, which is necessary for support structures particularly used in AM for mega-scale construction such as architectures and sculptures to ensure printing success and accuracy of the printed model.

Social implications

With the rapid development of AM, complicated structures result from topology optimization are available for fabrication. The present paper demonstrates a combination of AM and topology optimization, which is the trend of fabricating manner in the future.

Originality/value

This paper remarks the first of attempts to use continuum topology optimization method to generate support structures for AM. The methodology used in this work is theoretically meaningful and conclusions drawn in this paper can be of important instruction value and practical significance.

Details

Rapid Prototyping Journal, vol. 25 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

Srikanta Routroy, Sudeep Kumar Pradhan and C.V. Sunil Kumar

The purpose of this paper is to quantify, evaluate and compare the implementation performance of a supplier development (SD) program using graph theoretic approach (GTA).

Abstract

Purpose

The purpose of this paper is to quantify, evaluate and compare the implementation performance of a supplier development (SD) program using graph theoretic approach (GTA).

Design/methodology/approach

Broadly 13 critical success factors (CSFs) were identified and they were classified into four significant categories (SCs). Featuring these SCs and CSFs under each SC, GTA was proposed for evaluating the implementation performance of SD programs. The analysis was further extended to evaluate the performance of a SD program along the timeline to capture the other influences (if any), eventually compare the results with different performance situations and accordingly set the future targets.

Findings

In order to demonstrate the utility of the proposed approach it was applied to an Indian manufacturing company. The results obtained shown that there has been a significant growth achieved in the implementation performance of a SD program over a period of three years (i.e. 12 quarters) along the chosen SCs and CSFs under each SC. It was also found that still there was a performance gap and scope for improvement in the SD program of the case company.

Practical implications

The proposed approach is aimed at providing a procedure for evaluating the implementation performance of a SD program. This study is an attempt to assist a manufacturer to assess its SD program and accordingly define its course of actions.

Originality/value

Although many issues related to SD have been widely recognized and studied, there are no specific studies available in the literature to assess the implementation performance of SD programs along the timeline. The proposed model has the ability to capture the performance and interdependencies of SCs, CSFs under each SC and also to quantify the implementation performance of a SD program along the timeline.

Details

Asia Pacific Journal of Marketing and Logistics, vol. 28 no. 4
Type: Research Article
ISSN: 1355-5855

Keywords

To view the access options for this content please click here
Article

Chien-Feng Huang, Tsung-Nan Hsieh, Bao Rong Chang and Chih-Hsiang Chang

Stock selection has long been identified as a challenging task. This line of research is highly contingent upon reliable stock ranking for successful portfolio…

Abstract

Purpose

Stock selection has long been identified as a challenging task. This line of research is highly contingent upon reliable stock ranking for successful portfolio construction. The purpose of this paper is to employ the methods from computational intelligence (CI) to solve this problem more effectively.

Design/methodology/approach

The authors develop a risk-adjusted strategy to improve upon the previous stock selection models by two main risk measures – downside risk and variation in returns. Moreover, the authors employ the genetic algorithm for optimization of model parameters and selection for input variables simultaneously.

Findings

It is found that the proposed risk-adjusted methodology via maximum drawdown significantly outperforms the benchmark and improves the previous model in the performance of stock selection.

Research limitations/implications

Future work considers an extensive study for the risk-adjusted model using other risk measures such as Value at Risk, Block Maxima, etc. The authors also intend to use financial data from other countries, if available, in order to assess if the method is generally applicable and robust across different environments.

Practical implications

The authors expect this risk-adjusted model to advance the CI research for financial engineering and provide an promising solutions to stock selection in practice.

Originality/value

The originality of this work is that maximum drawdown is being successfully incorporated into the CI-based stock selection model in which the model's effectiveness is validated with strong statistical evidence.

Details

Engineering Computations, vol. 31 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article

Srikanta Routroy and Sudeep Kumar Pradhan

The first objective of this paper is to identify the critical success factors (CSFs) and their corresponding key performance indicators (KPIs) for supplier development…

Abstract

Purpose

The first objective of this paper is to identify the critical success factors (CSFs) and their corresponding key performance indicators (KPIs) for supplier development (SD) in a manufacturing environment. The second objective is to develop a methodology to analyze and evaluate the performance for SD using CSFs and their KPIs over the time.

Design/methodology/approach

In all, 13 CSFs and their corresponding KPIs for SD are established through an extensive literature review, discussion held with managers/engineers in different Indian manufacturing companies and conducting brainstorming sessions. A methodology is proposed using analytic hierarchy process (AHP) and performance value analysis to assess and evaluate the performance of SD over the time.

Findings

From an extensive analysis of the results, under the given circumstances, the growth of SD performance is positive at different progressive points along the time horizon.

Research limitations/implications

This study has not been statistically validated in manufacturing supply chain for complete acceptability.

Practical implications

This study provides insights into the performance evaluation of SD using CSFs and their corresponding KPIs. The managers should capture their manufacturing environment which can reflect their own priority considerations to establish the impact of each KPI on its corresponding CSF.

Originality/value

Although many issues related to SD have been widely researched individually, few studies have been reported with a model to quantify, monitor, analyze, and evaluate the growth of SD performance in manufacturing environment in Indian context. The proposed model has the ability to capture the performance along KPIs and CSFs to draw fruitful conclusions regarding the success of the SD programme.

Details

International Journal of Productivity and Performance Management, vol. 63 no. 2
Type: Research Article
ISSN: 1741-0401

Keywords

To view the access options for this content please click here
Article

Mohammad M. Rahman, Ziad Saghir and Ioan Pop

This paper aims to investigate numerically the free convective heat transfer efficiency inside a rectotrapezoidal enclosure filled with Al2O3–Cu/water hybrid fluid. The…

Abstract

Purpose

This paper aims to investigate numerically the free convective heat transfer efficiency inside a rectotrapezoidal enclosure filled with Al2O3–Cu/water hybrid fluid. The bottom wall of the cavity is uniformly heated, the upper horizontal wall is insulated, and the remaining walls are considered cold. A new thermophysical relation determining the thermal conductivity of the hybrid nanofluid has been established, which produced results those match with experimental ones.

Design/methodology/approach

The governing partial differential equations are solved using the finite element method of Galerkin type. The simulated results in terms of streamlines, heat lines and isotherms are displayed for various values of the model parameters, which govern the flow.

Findings

The Nusselt number, friction factor and the thermal efficiency index are also determined for the pertinent parameters varying different ratios of the hybrid nanoparticles. The simulated results showed that thermal buoyancy significantly controls the heat transfer, friction factor and thermal efficiency index. The highest thermal efficiency is obtained for the lowest Rayleigh number.

Practical implications

This theoretical study is significantly relevant to the applications of the hybrid nanofluids electronic devices cooled by fans, manufacturing process, renewable energies, nuclear reactors, electronic cooling, lubrication, refrigeration, combustion, medicine, thermal storage, etc.

Originality/value

The results showed that nanoparticle loading intensified the rate of heat transfer and thermal efficiency index at the expense of the higher friction factor or higher pumping power. The results further show that the heat transmission in Al2O3–Cu/water hybrid nanofluid at a fixed value of intensified $\phi_{hnf}$ compared to the Al2O3/water nanofluid when an amount of higher conductivity nanoparticles (Cu) added to it. Besides, the rate of heat transfer in Cu/water nanofluid declines when the lower thermal conductivity Al2O3 nanoparticles are added to the mixture.

Details

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

Keywords

To view the access options for this content please click here
Article

Talah S. Arabiyat, Metri Mdanat, Mohamed Haffar, Ahmad Ghoneim and Omar Arabiyat

The purpose of this paper is to improve understanding of how different aspects of the national institutional environment may influence the extent of innovative…

Abstract

Purpose

The purpose of this paper is to improve understanding of how different aspects of the national institutional environment may influence the extent of innovative entrepreneurial activities across countries. Several institutional and conductive factors affecting a country’s capacity to support innovative entrepreneurship are explored.

Design/methodology/approach

Institutional theory is used to examine the national regulatory, normative, cognitive and conducive aspects that measure a country’s ability to support innovative entrepreneurship. A cross-national institutional profile is constructed to validate an entrepreneurial innovation model. The impacts of country-level national institutions on innovative entrepreneurial activity as measured by Global Entrepreneurship Monitor data are assessed through structural equation modeling.

Findings

Knowledge about the influence of specific institutional aspects on innovative entrepreneurship, and hence of institutional structures within and across countries, is enhanced. For new innovative enterprises, conductive and regulatory aspects seem to matter most. All conductive factors have a significant and positive impact on entrepreneurial activity rates.

Research limitations/implications

Results could support policy makers and practitioners in evaluating government policies’ effects on innovative entrepreneurship. Interventions should target both individual attributes and context. Future research could include longitudinal designs to measure the direction of causality.

Practical implications

Aspects such as regulatory institutions, and conductive factors such as information communication technology use and technology adoption, are important for innovation entrepreneurship development.

Originality/value

The literature on institutional theory and innovative entrepreneurship is highly limited. This study complements growing interest in empirical analysis of the effects of national institutions on innovative entrepreneurial activities and substantiates previous empirical work.

Details

Journal of Enterprise Information Management, vol. 32 no. 3
Type: Research Article
ISSN: 1741-0398

Keywords

To view the access options for this content please click here
Article

Mohsen Izadi, Nemat M. Maleki, Ioan Pop and S.A.M. Mehryan

This paper aims to numerically investigate the natural convection heat transfer of a hybrid nanofluid into a porous cavity exposed to a variable magnetic field.

Abstract

Purpose

This paper aims to numerically investigate the natural convection heat transfer of a hybrid nanofluid into a porous cavity exposed to a variable magnetic field.

Design/methodology/approach

The non-linear elliptical governing equations have been solved numerically using control volume based finite element method. The effects of different governing parameters including Rayleigh number (Ra = 103 − 106), Hartman number (Ha = 0 − 50), volume fraction of nanoparticles (φ = 0 − 0.02), curvature of horizontal isolated wall (a = 0.85 − 1.15), porosity coefficient (ε = 0.1 − 0.9) and Darcy number (Da = 10−5 − 10−1) have been studied.

Findings

The results indicate that at low Darcy numbers close to 0, the average Nusselt number Nua enhances as porosity coefficient increases. For a = 1 and a = 1.15 in comparison with a = 0.85, the stretching of the isothermal lines is maintained from the left side to the right side and vice versa, which indicates increased natural convection heat transfer for this configuration of the top and bottom walls. In addition, at higher Rayleigh numbers, by increasing the Hartmann number, a significant decrease is observed in the Nusselt number, which can be attributed to the decreased power of the flow.

Originality/value

The authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article

Raquel Ferreras-Garcia, Jordi Sales-Zaguirre and Enric Serradell-López

The aim of this article is to propose and test a structural model of relationships between generic and specific competencies and entrepreneurial competencies in order to…

Abstract

Purpose

The aim of this article is to propose and test a structural model of relationships between generic and specific competencies and entrepreneurial competencies in order to assess students' learning.

Design/methodology/approach

The study was carried out on a sample of 337 students enrolled on the entrepreneurship specialisation of the final bachelor's degree project course on the Bachelor's Degree in Business Administration and Management at the Universitat Oberta de Catalunya. A questionnaire was designed to gather information on students' perception of their level of acquisition of the different groups of competencies. The partial least squares (PLS) multivariate technique was used to analyse the model.

Findings

The results confirm that there are significant relationships between the different groups of competencies. Specifically, it shows that generic competencies influence specific competencies and that there is a strong relationship between systemic and professional competencies and entrepreneurial competencies. It also shows that the experience variable contributes positively to different competency groups, while the gender and age variables have no effect on the development of entrepreneurial competencies.

Practical implications

The study provides relevant information to the academic world on different factors that affect competency development.

Originality/value

The analysis provides an innovative research and contributes knowledge on entrepreneurial competency acquisition, providing an answer to whether generic and specific competencies influence entrepreneurial competencies.

Details

Education + Training, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0040-0912

Keywords

1 – 10 of 16