Eduardo Krempser, Heder S. Bernardino, Helio J.C. Barbosa and Afonso C.C. Lemonge
The purpose of this paper is to propose and analyze the use of local surrogate models to improve differential evolution’s (DE) overall performance in computationally expensive…
Abstract
Purpose
The purpose of this paper is to propose and analyze the use of local surrogate models to improve differential evolution’s (DE) overall performance in computationally expensive problems.
Design/methodology/approach
DE is a popular metaheuristic to solve optimization problems with several variants available in the literature. Here, the offspring are generated by means of different variants, and only the best one, according to the surrogate model, is evaluated by the simulator. The problem of weight minimization of truss structures is used to assess DE’s performance when different metamodels are used. The surrogate-assisted DE techniques proposed here are also compared to common DE variants. Six different structural optimization problems are studied involving continuous as well as discrete sizing design variables.
Findings
The use of a local, similarity-based, surrogate model improves the relative performance of DE for most test-problems, specially when using r-nearest neighbors with r = 0.001 and a DE parameter F = 0.7.
Research limitations/implications
The proposed methods have no limitations and can be applied to solve constrained optimization problems in general, and structural ones in particular.
Practical/implications
The proposed techniques can be used to solve real-world problems in engineering. Also, the performance of the proposals is examined using structural engineering problems.
Originality/value
The main contributions of this work are to introduce and to evaluate additional local surrogate models; to evaluate the effect of the value of DE’s parameter F (which scales the differences between components of candidate solutions) upon each surrogate model; and to perform a more complete set of experiments covering continuous as well as discrete design variables.
Details
Keywords
Afonso C.C Lemonge, Helio J.C. Barbosa and Heder S. Bernardino
– The purpose of this paper is to propose variants of an adaptive penalty scheme for steady-state genetic algorithms applied to constrained engineering optimization problems.
Abstract
Purpose
The purpose of this paper is to propose variants of an adaptive penalty scheme for steady-state genetic algorithms applied to constrained engineering optimization problems.
Design/methodology/approach
For each constraint a penalty parameter is adaptively computed along the evolution according to information extracted from the current population such as the existence of feasible individuals and the level of violation of each constraint. The adaptive penalty method (APM), as originally proposed, computes the constraint violations of the initial population, and updates the penalty coefficient of each constraint after a given number of new individuals are inserted in the population. A second variant, called sporadic APM with constraint violation accumulation, works by accumulating the constraint violations during a given insertion of new offspring into the population, updating the penalty coefficients, and fixing the penalty coefficients for the next generations. The APM with monotonic penalty coefficients is the third variation, where the penalty coefficients are calculated as in the original method, but no penalty coefficient is allowed to have its value reduced along the evolutionary process. Finally, the penalty coefficients are defined by using a weighted average between the current value of a coefficient and the new value predicted by the method. This variant is called the APM with damping.
Findings
The paper checks new variants of an APM for evolutionary algorithms; variants of an APM, for a steady-state genetic algorithm based on an APM for a generational genetic algorithm, largely used in the literature previously proposed by two co-authors of this manuscript; good performance of the proposed APM in comparison with other techniques found in the literature; innovative and general strategies to handle constraints in the field of evolutionary computation.
Research limitations/implications
The proposed algorithm has no limitations and can be applied in a large number of evolutionary algorithms used to solve constrained optimization problems.
Practical implications
The proposed algorithm can be used to solve real world problems in engineering as can be viewed in the references, presented in this manuscript, that use the original (APM) strategy. The performance of these variants is examined using benchmark problems of mechanical and structural engineering frequently discussed in the literature.
Originality/value
It is the first extended analysis of the variants of the APM submitted for possible publication in the literature, applied to real world engineering optimization problems.
Details
Keywords
Barbara de Lima Voss, David Bernard Carter and Bruno Meirelles Salotti
We present a critical literature review debating Brazilian research on social and environmental accounting (SEA). The aim of this study is to understand the role of politics in…
Abstract
We present a critical literature review debating Brazilian research on social and environmental accounting (SEA). The aim of this study is to understand the role of politics in the construction of hegemonies in SEA research in Brazil. In particular, we examine the role of hegemony in relation to the co-option of SEA literature and sustainability in the Brazilian context by the logic of development for economic growth in emerging economies. The methodological approach adopts a post-structural perspective that reflects Laclau and Mouffe’s discourse theory. The study employs a hermeneutical, rhetorical approach to understand and classify 352 Brazilian research articles on SEA. We employ Brown and Fraser’s (2006) categorizations of SEA literature to help in our analysis: the business case, the stakeholder–accountability approach, and the critical case. We argue that the business case is prominent in Brazilian studies. Second-stage analysis suggests that the major themes under discussion include measurement, consulting, and descriptive approach. We argue that these themes illustrate the degree of influence of the hegemonic politics relevant to emerging economics, as these themes predominantly concern economic growth and a capitalist context. This paper discusses trends and practices in the Brazilian literature on SEA and argues that the focus means that SEA avoids critical debates of the role of capitalist logics in an emerging economy concerning sustainability. We urge the Brazilian academy to understand the implications of its reifying agenda and engage, counter-hegemonically, in a social and political agenda beyond the hegemonic support of a particular set of capitalist interests.
Details
Keywords
Ricardo Pires de Souza, Hélio Roberto Hékis, Lucas Ambrósio Bezerra Oliveira, Jamerson Viegas Queiroz, Fernanda Cristina Barbosa Pereira Queiroz and Ricardo Alexsandro de Medeiros Valentim
The Six Sigma project aims at a continual reduction in process variation, eliminating defects or flaws in products and services, optimizing processes and reducing costs. The…
Abstract
Purpose
The Six Sigma project aims at a continual reduction in process variation, eliminating defects or flaws in products and services, optimizing processes and reducing costs. The purpose of this study is to demonstrate improvements in customer service index (CSI), product cycle time and inventory turnover after implementation of a Six Sigma project.
Design/methodology/approach
This research focused on the value stream mapping of a company process, performed by a multidisciplinary team that implemented a pull production system, the standard operational procedure in machines that were process bottlenecks, and the kanban system.
Findings
After three months of implementation, the authors observed an 11.7 percent reduction in product cycle time, increase in customer service index (CSI) from 93.9 to 97 percent and increase in inventory turnovers from 4.9 to 9.
Originality/value
The project was in accordance with the competitive strategy of the company, which is focused on customer satisfaction and cost reduction.
Details
Keywords
Susanne Durst, Lena Aggestam and Helio Aisenberg Ferenhof
This paper aims to review research on the topic of knowledge leakage to establish the current body of knowledge and, on this basis, to suggest some promising avenues for future…
Abstract
Purpose
This paper aims to review research on the topic of knowledge leakage to establish the current body of knowledge and, on this basis, to suggest some promising avenues for future research.
Design/methodology/approach
The study consists of a systematic review of 57 refereed empirical articles on knowledge leakage.
Findings
The findings contribute to a more holistic view of the topic and complement the study of knowledge management. Additionally, a conceptual framework is proposed that aims at guiding and informing future research activities.
Research limitations/implications
This study may not have enabled a complete coverage of all empirical articles in the field of knowledge leakage. Yet, based on the chosen research methodology, it seems reasonable to assume that the review process covered a large share of studies available.
Originality/value
To the best of the authors’ knowledge, no systematic literature review on knowledge leakage has previously been published in academic journals.