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Article
Publication date: 18 November 2021

Ibrahim Ajani and Cong Lu

This paper aims to develop a mathematical method to analyze the assembly variation of the non-rigid assembly, considering the manufacturing variations and the deformation…

Abstract

Purpose

This paper aims to develop a mathematical method to analyze the assembly variation of the non-rigid assembly, considering the manufacturing variations and the deformation variations of the non-rigid parts during the assembly process.

Design/methodology/approach

First, this paper proposes a deformation gradient model, which represents the deformation variations during the assembly process by considering the forces and the self-weight of the non-rigid parts. Second, the developed deformation gradient models from the assembly process are integrated into the homogenous transformation matrix to model the deformation variations and manufacturing variations of the deformed non-rigid part. Finally, a mathematical model to analyze the assembly variation propagation is developed to predict the dimensional and geometrical variations due to the manufacturing variations and the deformation variations during the assembly process.

Findings

Through the case study with a crosshead non-rigid assembly, the results indicate that during the assembly process, the individual deformation values of the non-rigid parts are small. However, the cumulative deformation variations of all the non-rigid parts and the manufacturing variations present a target value (w) of −0.2837 mm as compared to a target value of −0.3995 mm when the assembly is assumed to be rigid. The difference in the target values indicates that the influence of the non-rigid part deformation variations during the assembly process on the mechanical assembly accuracy cannot be ignored.

Originality/value

In this paper, a deformation gradient model is proposed to obtain the deformation variations of non-rigid parts during the assembly process. The small deformation variation, which is often modeled using a finite-element method in the existing works, is modeled using the proposed deformation gradient model and integrated into the nominal dimensions. Using the deformation gradient models, the non-rigid part deformation variations can be computed and the accumulated deformation variation can be easily obtained. The assembly variation propagation model is developed to predict the accuracy of the non-rigid assembly by integrating the deformation gradient models into the homogeneous transformation matrix.

Details

Assembly Automation, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 29 July 2014

Yanfeng Xing and Yansong Wang

The purpose of this paper is to propose a new assembly variation analysis model to analyze assembly variation for sheet metal parts. The main focus is to analyze assembly…

Abstract

Purpose

The purpose of this paper is to propose a new assembly variation analysis model to analyze assembly variation for sheet metal parts. The main focus is to analyze assembly processes based on the method of power balance.

Design/methodology/approach

Starting with issues in assembly variation analysis, the review shows the critical aspects of tolerance analysis. The method of influence coefficient (MIC) cannot accurately analyze the relationship between part variations and assembly variations, as the welding point is not a point but a small area. Therefore, new sensitivity matrices are generated based on the method of power balance.

Findings

Here two cases illustrate the processes of assembly variation analysis, and the results indicate that new method has higher accuracy than the MIC.

Research limitations/implications

This study is limited to assembly variation analysis for sheet metal parts, which can be used in auto-body and airplane body.

Originality/value

This paper provides a new assembly variation analysis based on the method of power balance.

Details

Assembly Automation, vol. 34 no. 3
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 25 September 2009

Sun Jin, Kuigang Yu, Xinmin Lai and Yinhua Liu

The purpose of this paper is to focus on optimal sensor placement for the fixture variation diagnosis of compliant sheet metal assembly process. Fixture variations are the…

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433

Abstract

Purpose

The purpose of this paper is to focus on optimal sensor placement for the fixture variation diagnosis of compliant sheet metal assembly process. Fixture variations are the main sources for complex automotive body dimensional failures. An effective measurement strategy can help exactly and timely diagnose these fixture variations. Research on sensor placement strategy of compliant sheet metal assembly process is not much stated formerly.

Design/methodology/approach

The impact principle of fixture variations is analyzed to set up the relationship between the assembly variation and fixture variations applying the method of influence coefficients and the effective independence (EI) method is used to find the optimal sensor positions based on the impact principle analysis of fixture variations.

Findings

The obtained fixture variation sensitivity matrix describes the influence of fixture variations to compliant sheet metal assembly variation and can be used for diagnosing fixture variations. The EI method can effectively solve the optimal sensor positions for compliant sheet metal assembly by a case demonstration.

Originality/value

The proposed method can solve the sensor placement of online assembly station for diagnosing fixture variations. It takes the compliant characteristics of sheet metal parts into account and the sensor information has much greater diagnosability than that from applying other methods.

Details

Assembly Automation, vol. 29 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 11 September 2007

Faisal Manzoor Arain and Low Sui Pheng

This paper seeks to present research into the development of a theoretical model for making more informed decisions for the management of variations in building projects…

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1960

Abstract

Purpose

This paper seeks to present research into the development of a theoretical model for making more informed decisions for the management of variations in building projects. Primarily, the study proposes six principles of effective variation management, which would be helpful for building professionals in assessing and taking proactive measures for reducing the adverse impact of variations.

Design/methodology/approach

Based on the principles of effective variation management, a theoretical framework for management of variation orders was developed. The stages presented in the theoretical framework were grouped into three main phases – screening, choice of promising alternatives, and dominance building. Based on the theoretical framework, a model for management of variations was developed.

Findings

The theoretical model presents a structured format for management of variation orders. The model will enable the project team to take advantage of beneficial variations when the opportunity arises without an inordinate fear of the negative impacts. By having a systematic way to manage variations, the efficiency of project work and the likelihood of project success should increase.

Originality/value

The study would assist building professionals in developing an effective variation management system. The model emphasized sharing the lessons learned from existing projects with project teams of future projects. The lessons learned should be identified throughout the project life cycle and communicated to current and future project participants. The system would be helpful for them to take proactive measures for reducing variation orders. Hence, the study is valuable for all professionals involved with building projects.

Details

Engineering, Construction and Architectural Management, vol. 14 no. 5
Type: Research Article
ISSN: 0969-9988

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Book part
Publication date: 11 November 2014

Tatiana Albanez and Gerlando Augusto Sampaio Franco de Lima

According to the market timing theory, firms try to take advantage of windows of opportunity to raise capital by exploiting temporary cost fluctuations of alternative…

Abstract

Purpose

According to the market timing theory, firms try to take advantage of windows of opportunity to raise capital by exploiting temporary cost fluctuations of alternative financing sources. In this context, the main objective of this paper is to examine the influence and persistence of market timing in the financing decisions of Brazilian firms that launched IPOs in the period from 2001 to 2011.

Methodology/approach

We analyze the influence of past market values on the capital structure of these firms, based on the main models proposed by Baker and Wurgler (2002), adapted to reflect the characteristics of Brazilian firms’ financial statements.

Findings

We find evidence of market timing, but this behavior is not sufficiently persistent in the period studied to the point of determining these firms’ capital structure. We believe the fact that Brazilian companies rarely carried out follow-on primary equity issues after floating their capital in the period analyzed, due to the presence of more advantageous financing sources (particularly from the national development bank, BNDES), explains the results. Therefore, Brazilian firms appear to be pay heed to different funding sources, in search of windows of opportunity, to guide their financing decisions and determine their capital structures.

Originality/value

The Brazilian capital market has been developing intensely in recent years, making it increasingly relevant to analyze the financing and investment decisions of the country’s listed companies. The Brazilian literature on capital structure is extensive, but few works have addressed the issue of market timing.

Details

Emerging Market Firms in the Global Economy
Type: Book
ISBN: 978-1-78441-066-7

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Book part
Publication date: 1 July 2014

Samantha A. Conroy, Nina Gupta, Jason D. Shaw and Tae-Youn Park

In this paper, we review the literature on pay variation (e.g., pay dispersion, pay compression, pay range) in organizations. Pay variation research has increased markedly…

Abstract

In this paper, we review the literature on pay variation (e.g., pay dispersion, pay compression, pay range) in organizations. Pay variation research has increased markedly in the past two decades and much progress has been made in terms of understanding its consequences for individual, team, and organizational outcomes. Our review of this research exposes several levels-related assumptions that have limited theoretical and empirical progress. We isolate the issues that deserve attention, develop an illustrative multilevel model, and offer a number of testable propositions to guide future research on pay structures.

Details

Research in Personnel and Human Resources Management
Type: Book
ISBN: 978-1-78350-824-2

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Abstract

Details

The Efficiency of Mutual Fund Families
Type: Book
ISBN: 978-1-78743-799-9

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Book part
Publication date: 16 July 2015

Martine Lappé and Hannah Landecker

This study analyzes the rise of genome instability in the life sciences and traces the problematic of instability as it relates to the sociology of health. Genome…

Abstract

Purpose

This study analyzes the rise of genome instability in the life sciences and traces the problematic of instability as it relates to the sociology of health. Genome instability is the study of how genomes change and become variable between generations and within organisms over the life span. Genome instability reflects a significant departure from the Platonic genome imagined during the Human Genome Project. The aim of this chapter is to explain and analyze research on copy number variation and somatic mosaicism to consider the implications of these sciences for sociologists interested in genomics.

Methodology/approach

This chapter draws on two multi-sited ethnographies of contemporary biomedical science and literature in the sociology of health, science, and biomedicine to document a shift in thinking about the genome from fixed and universal to highly variable and influenced by time and context.

Findings

Genomic instability has become a framework for addressing how genomes change and become variable between generations and within organisms over the life span. Instability is a useful framework for analyzing changes in the life sciences in the post-genomic era.

Research implications

Genome instability requires life scientists to address how differences both within and between individuals articulate with shifting disease categories and classifications. For sociologists, these findings have implications for studies of identity, sociality, and clinical experience.

Originality/value

This is the first sociological analysis of genomic instability. It identifies practical and conceptual implications of genomic instability for life scientists and helps sociologists delineate new approaches to the study of genomics in the post-genomic era.

Details

Genetics, Health and Society
Type: Book
ISBN: 978-1-78350-581-4

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Article
Publication date: 2 December 2020

Zeeshan Mahmood and Shahzad Uddin

This paper aims to deepen the understanding of logics and practice variation in sustainability reporting in an emerging field.

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1000

Abstract

Purpose

This paper aims to deepen the understanding of logics and practice variation in sustainability reporting in an emerging field.

Design/methodology/approach

This paper adopts the institutional logics perspective and its conceptualization of society as an inter-institutional system as a theoretical lens to understand reasons for the presence of and variation in sustainability reporting. The empirical findings are based on analysis of 28 semi-structured interviews with significant social actors, and extensive documentary evidence focusing on eight companies pioneering sustainability reporting in Pakistan.

Findings

This paper confirms the presence of multiple co-existing logics in sustainability practices and lack of a dominant logic. Sustainability reporting practices are underpinned by a combination of market and corporate (business logics), state (regulatory logics), professional (transparency logics) and community (responsibility logics) institutional orders. It is argued that institutional heterogeneity (variations in logics) drives the diversity of motivations for and variations in sustainability reporting practices.

Research limitations/implications

The paper offers a deeper theoretical explanation of how various logics dominate sustainability reporting in a field where the institutionalization of practice is in its infancy.

Practical implications

Understanding the conditions that influence the logics of corporate decision-makers will provide new insights into what motivates firms to engage in sustainability reporting. A broader understanding of sustainability reporting in emerging fields will foster its intended use to increase transparency, accountability and sustainability performance.

Originality/value

This paper contributes to relatively scarce but growing empirical research on emerging fields. Its major contribution lies in its focus on how multiple and conflicting institutional logics are instantiated at the organizational level, leading to wide practice variations, especially in an emerging field. In doing so, it advances the institutional logics debate on practice variations within the accounting literature.

Details

Accounting, Auditing & Accountability Journal, vol. 34 no. 5
Type: Research Article
ISSN: 0951-3574

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Article
Publication date: 20 January 2021

B.A.K.S. Perera, D.C. Sirimewan and A.D. Senadeera

Many public-sector building projects in developing countries are prone to variations owing to the changes made to their original project scopes, and economic depressions…

Abstract

Purpose

Many public-sector building projects in developing countries are prone to variations owing to the changes made to their original project scopes, and economic depressions and stagnations. Cost and time-overruns are consequences of such variations. Thus, variation management in these projects is important. Hence, this paper aims to analyse the methods of managing variations in public-sector building projects in Sri Lanka.

Design/methodology/approach

The study adopted a mixed research approach. Seventeen expert interviews and a questionnaire survey were conducted to identify the causes and consequences of the variations, and the strategies that will help manage those variations. Manual content analysis and mean weighted rankings (MWR) were used to analyse the collected quantitative and qualitative data, respectively.

Findings

The employer, consultant, contractor and several other factors are mostly responsible for the variations in public-sector building projects in Sri Lanka. Cost and time-overruns, rework and demolition and disputes are the major consequences of such variations. The study findings reveal that a detailed employer’s brief, clearly defined project objectives, a comprehensive design and set of specifications, and preliminary investigations are the strategies that will mostly minimise the variations in public-sector building projects in Sri Lanka.

Originality/value

The study proposes strategies to avoid or minimise the adverse impact of variations, which the industry practitioners can adopt for variation management in public-sector building projects. The study theoretically contributes to knowledge by revealing how variations in public-sector building projects in Sri Lanka can be managed by identifying their causes and consequences.

Details

Journal of Engineering, Design and Technology , vol. 19 no. 6
Type: Research Article
ISSN: 1726-0531

Keywords

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