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Article
Publication date: 9 February 2021

Christian Stockmann, Herwig Winkler and Martin Kunath

The concept of robustness in manufacturing is not easy to capture and even harder to quantify. This paper elaborates an approach to assess robustness in production systems…

Abstract

Purpose

The concept of robustness in manufacturing is not easy to capture and even harder to quantify. This paper elaborates an approach to assess robustness in production systems from a holistic input-throughput-output perspective using a pragmatic robustness indicator.

Design/methodology/approach

First, in order to have a precise understanding of what needs to be measured, a concept of robustness in production systems is defined based on a literature overview. Three different aspects are considered to be essential to comprehensively describe robustness in production: the deviations of input resources, of performance and of output. These aspects are translated into an aggregated indicator based on developments of production costs, order delays and output volumes. The indicator-based assessment approach is eventually applied to a flow-shop scheduling case study in the chipboard industry.

Findings

The study shows that an assessment of robustness should not solely focus on a single aspect of a production system. Instead, a holistic view is required addressing the tradeoffs that robustness must balance, such as the one between the realized performance, the corresponding resource requirements and the resulting output. Furthermore, the study emphasizes that robustness can be interpreted as a superior system capability that builds upon flexibility, agility, resilience and resistance.

Research limitations/implications

First, the paper is a call to further test and validate the proposed approach in industry case studies. Second, the paper suggests a modified understanding of robustness in production systems in which not only the deviation of one single variable is of interest but also the behavior of the whole system.

Practical implications

The approach allows practitioners to pragmatically evaluate a production system’s robustness level while quickly identifying drivers, barriers and tradeoffs.

Originality/value

Compared to existing assessment approaches the proposed methodology is one of the first that evaluates robustness in production systems from a holistic input-throughput-output perspective highlighting the different tradeoffs that have to be balanced. It is based upon a comprehensive concept of robustness which also links robustness to adjacent capabilities that were otherwise only treated separately.

Details

Journal of Manufacturing Technology Management, vol. 32 no. 4
Type: Research Article
ISSN: 1741-038X

Keywords

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Article
Publication date: 29 May 2020

Jianyu Zhao, Anzhi Bai, Xi Xi, Yining Huang and Shanshan Wang

Malicious attacks extremely traumatize knowledge networks due to increasing interdependence among knowledge elements. Therefore, exposing the damage of malicious attacks…

Abstract

Purpose

Malicious attacks extremely traumatize knowledge networks due to increasing interdependence among knowledge elements. Therefore, exposing the damage of malicious attacks to knowledge networks has important theoretical and practical significance. Despite the insights being offered by the growing research stream, few studies discuss the diverse responses of knowledge networks’ robustness to different target-attacks, and the authors lack sufficient knowledge of which forms of malicious attacks constitute greater disaster when knowledge networks evolve to different stages. Given the irreversible consequences of malicious attacks on knowledge networks, this paper aims to examine the impacts of different malicious attacks on the robustness of knowledge networks.

Design/methodology/approach

On the basic of dividing malicious attacks into six forms, the authors incorporate two important aspects of robustness of knowledge networks – structure and function – in a research framework, and use maximal connected sub-graphs and network efficiency, respectively, to measure structural and functional robustness. Furthermore, the authors conceptualize knowledge as a multi-dimensional structure to reflect the heterogeneous nature of knowledge elements, and design the fundamental rules of simulation. NetLogo is used to simulate the features of knowledge networks and their changes of robustness as they face different malicious attacks.

Findings

First, knowledge networks gradually form more associative integrated structures with evolutionary progress. Second, various properties of knowledge elements play diverse roles in mitigating damage from malicious attacks. Recalculated-degree-based attacks cause greater damage than degree-based attacks, and structure of knowledge networks has higher resilience against ability than function. Third, structural robustness is mainly affected by the potential combinatorial value of high-degree knowledge elements, and the combinatorial potential of high-out-degree knowledge elements. Forth, the number of high in-degree knowledge elements with heterogeneous contents, and the inverted U-sharp effect contributed by high out-degree knowledge elements are the main influencers of functional robustness.

Research limitations/implications

The authors use the frontier method to expose the detriments of malicious attacks both to structural and functional robustness in each evolutionary stage, and the authors reveal the relationship and effects of knowledge-based connections and knowledge combinatorial opportunities that contribute to maintaining them. Furthermore, the authors identify latent critical factors that may improve the structural and functional robustness of knowledge networks.

Originality/value

First, from the dynamic evolutionary perspective, the authors systematically examine structural and functional robustness to reveal the roles of the properties of knowledge element, and knowledge associations to maintain the robustness of knowledge networks. Second, the authors compare the damage of six forms of malicious attacks to identify the reasons for increased robustness vulnerability. Third, the authors construct the stock, power, expertise knowledge structure to overcome the difficulty of knowledge conceptualization. The results respond to multiple calls from different studies and extend the literature in multiple research domains.

Details

Journal of Knowledge Management, vol. 24 no. 5
Type: Research Article
ISSN: 1367-3270

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Article
Publication date: 29 May 2020

Lihui Zhang, Guyu Dai, Xin Zou and Jianxun Qi

Interrupting work continuity provides a way to improve some project performance, but unexpected and harmful interruptions may impede the implementation. This paper aims to…

Abstract

Purpose

Interrupting work continuity provides a way to improve some project performance, but unexpected and harmful interruptions may impede the implementation. This paper aims to mitigate the negative impact caused by work continuity uncertainty based on the notion of robustness.

Design/methodology/approach

This paper develops a float-based robustness measurement method for the work continuity uncertainty in repetitive projects. A multi-objective optimization model is formulated to generate a schedule that achieves a balance between crew numbers and robustness. This model is solved using two modules: optimization module and decision-making module. The Monte Carlo simulation is designed to validate the effectiveness of the generated schedule.

Findings

The results confirmed that it is necessary to consider the robustness as an essential factor when scheduling a repetitive project with uncertainty. Project managers may develop a schedule that is subject to delays if they only make decisions according to the results of the deadline satisfaction problem. The Monte Carlo simulation validated that an appropriate way to measure robustness is conducive to generating a schedule that can avoid unnecessary delay, compared to the schedule generated by the traditional model.

Originality/value

Available studies assume that the work continuity is constant, but it cannot always be maintained when affected by uncertainty. This paper regards the work continuity as a new type of uncertainty factor and investigates how to mitigate its negative effects. The proposed float-based robustness measurement can measure the ability of a schedule to absorb unpredictable and harmful interruptions, and the proposed multi-objective scheduling model provides a way to incorporate the uncertainty into a schedule.

Details

Engineering, Construction and Architectural Management, vol. 27 no. 10
Type: Research Article
ISSN: 0969-9988

Keywords

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Article
Publication date: 4 August 2021

Shih-Jung Juan, Eldon Y. Li and Wei-Hsi Hung

This study aims to explore the relationships among the five components of supply chain (SC) resilience (SCRES): visibility, velocity, flexibility, robustness and…

Abstract

Purpose

This study aims to explore the relationships among the five components of supply chain (SC) resilience (SCRES): visibility, velocity, flexibility, robustness and collaboration and their impacts on the SC performance under disruption (SCPUD).

Design/methodology/approach

Five SCRES components are identified from the literature review and data are collected using an web survey from 113 manufacturing companies in Taiwan. The data are analyzed by structured equation modeling with the partial least square solution. Two-stage least-squares (2SLS) regression was used to test the potential endogeneity of SC collaboration (SCC).

Findings

The results reveal that SCC is an exogenous driver of SCRES; it directly affects visibility, velocity, flexibility, robustness and SCPUD. Furthermore, SC flexibility is the only component of SC agility that directly affects SCPUD; it is influenced directly by SC velocity and indirectly by SC visibility through SC velocity. SC visibility is a vital agility component that positively influences SC velocity and SC robustness.

Research limitations/implications

The data in this study are cross-sectional and the sample size of 113 is relatively small. The relationship between SC robustness and SCPUD needs a longer observation period to reveal. The logistic issue in the shortage of carriers caused by the pandemic has been overlooked.

Practical implications

A firm should enhance its collaboration and flexibility in the SC as they both are the critical antecedents of SC performance (SCP) during the disruption period.

Originality/value

This study integrates visibility, velocity, flexibility, robustness and collaboration into a complete framework of SCRES. The dependent variable, SCPUD, measures SC performance (SCP) under the disruption caused by the COVID-19 pandemic. It is the first study to investigate the associations of the six constructs in a research model.

Details

The International Journal of Logistics Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0957-4093

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Article
Publication date: 1 July 2014

Fábio Ribeiro Soares da Cunha, Tobias Wille, Richard Degenhardt, Michael Sinapius, Francisco Célio de Araújo and Rolf Zimmermann

– The purpose of this paper is to present the probabilistic approach to a new robustness-based design strategy for thin-walled composite structures in post-buckling.

Abstract

Purpose

The purpose of this paper is to present the probabilistic approach to a new robustness-based design strategy for thin-walled composite structures in post-buckling.

Design/methodology/approach

Because inherent uncertainties in geometry, material properties, ply orientation and thickness affect the structural performance and robustness, these variations are taken into account.

Findings

The methodology is demonstrated for the sake of simplicity with an unstiffened composite plate under compressive loading, and the probabilistic and deterministic results are compared. In this context, the structural energy and uncertainties are employed to investigate the robustness and reliability of thin-walled composite structures in post-buckling.

Practical implications

As practical implication, the methodology can be extended to stiffened shells, widely used in aerospace design with the aim to satisfy weight, strength and robustness requirements. Moreover, a new argument is strengthened to accept the collapse close to ultimate load once robustness is ensured with a required reliability.

Originality/value

This innovative strategy embedded in a probabilistic framework might lead to a different design selection when compared to a deterministic approach, or an approach that only accounts for the ultimate load. Moreover, robustness measures are redefined in the context of a probabilistic design.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 86 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 1 December 2005

Yakov Ben‐Haim

To study the effect of Knightian uncertainty – as opposed to statistical estimation error – in the evaluation of value‐at‐risk (VaR) of financial investments. To develop…

Abstract

Purpose

To study the effect of Knightian uncertainty – as opposed to statistical estimation error – in the evaluation of value‐at‐risk (VaR) of financial investments. To develop methods for augmenting existing VaR estimates to account for Knightian uncertainty.

Design/methodology/approach

The value at risk of a financial investment is assessed as the quantile of an estimated probability distribution of the returns. Estimating a VaR from historical data entails two distinct sorts of uncertainty: probabilistic uncertainty in the estimation of a probability density function (PDF) from historical data, and non‐probabilistic Knightian info‐gaps in the future size and shape of the lower tail of the PDF. A PDF is estimated from historical data, while a VaR is used to predict future risk. Knightian uncertainty arises from the structural changes, surprises, etc., which occur in the future and therefore are not manifested in historical data. This paper concentrates entirely on Knightian uncertainty and does not consider the statistical problem of estimating a PDF. Info‐gap decision theory is used to study the robustness of a VaR to Knightian uncertainty in the distribution.

Findings

It is shown that VaRs, based on estimated PDFs, have no robustness to Knightian errors in the PDF. An info‐gap safety factor is derived that multiplies the estimated VaR in order to obtain a revised VaR with specified robustness to Knightian error in the PDF. A robustness premium is defined as a supplement to the incremental VaR for comparing portfolios.

Practical implications

The revised VaR and incremental VaR augment existing tools for evaluating financial risk.

Originality/value

Info‐gap theory, which underlies this paper, is a non‐probabilistic quantification of uncertainty that is very suitable for representing Knightian uncertainty. This enables one to assess the robustness to future surprises, as distinct from existing statistical techniques for assessing estimation error resulting from randomness of historical data.

Details

The Journal of Risk Finance, vol. 6 no. 5
Type: Research Article
ISSN: 1526-5943

Keywords

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Article
Publication date: 1 January 1982

CHAD D. ELLETT and JOSEPH W. LICATA

A total of 264 elementary and secondary school teachers in a southeastern state completed the Robustness Semantic Differential for concepts focusing on their role, their…

Abstract

A total of 264 elementary and secondary school teachers in a southeastern state completed the Robustness Semantic Differential for concepts focusing on their role, their principal's role and the role of students in school organization. They also completed the School Survey, a multidimensional measure of their attitudes toward their work environment. As hypothesized, results of multiple regression analyses produced significant positive correlations between the following variable sets: 1) the robustness of the teaching role and attitudes about professional performance and development, 2) the robustness of the principal's role and attitudes about supervisory relations, and 3) the robustness of the student role and attitudes toward the educational effectiveness of the school and its programs.

Details

Journal of Educational Administration, vol. 20 no. 1
Type: Research Article
ISSN: 0957-8234

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Article
Publication date: 12 April 2013

Gerald Sundaraj and David Eaton

The purpose of this paper is to define and quantify the term robustness within the context of a Private Finance Initiative (PFI) project environment from the perspective…

Abstract

Purpose

The purpose of this paper is to define and quantify the term robustness within the context of a Private Finance Initiative (PFI) project environment from the perspective of the Granting Authority. The paper is conceptual, based on conceptual generalisations.

Design/methodology/approach

The paper considers the theory of systems thinking within PFI procurement. This is further integrated with the concept of robustness and resilience used extensively in the ecology discipline. Combining the two, this paper presents a mathematical approach of quantifying robustness in PFI projects.

Findings

An analytical model is used to support the mathematical analysis to quantify and define robustness.

Research limitations/implications

The quantifying of robustness is based on the principal assumptions presented in the paper. The principal assumptions provide an ideal situation which is necessary to pursue and develop the proposed approach to quantify robustness. Changes to the assumptions may affect the generalisability of the approach.

Originality/value

The paper provides a greater definition to robustness within PFI projects and the possibility of quantifying robustness to better monitor and manage the characteristic.

Details

Journal of Financial Management of Property and Construction, vol. 18 no. 1
Type: Research Article
ISSN: 1366-4387

Keywords

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Article
Publication date: 5 May 2015

Garrison Stevens, Kendra Van Buren, Elizabeth Wheeler and Sez Atamturktur

Numerical models are being increasingly relied upon to evaluate wind turbine performance by simulating phenomena that are infeasible to measure experimentally. These…

Abstract

Purpose

Numerical models are being increasingly relied upon to evaluate wind turbine performance by simulating phenomena that are infeasible to measure experimentally. These numerical models, however, require a large number of input parameters that often need to be calibrated against available experiments. Owing to the unavoidable scarcity of experiments and inherent uncertainties in measurements, this calibration process may yield non-unique solutions, i.e. multiple sets of parameters may reproduce the available experiments with similar fidelity. The purpose of this paper is to study the trade-off between fidelity to measurements and the robustness of this fidelity to uncertainty in calibrated input parameters.

Design/methodology/approach

Here, fidelity is defined as the ability of the model to reproduce measurements and robustness is defined as the allowable variation in the input parameters with which the model maintains a predefined level of threshold fidelity. These two vital attributes of model predictiveness are evaluated in the development of a simplified finite element beam model of the CX-100 wind turbine blade.

Findings

Findings of this study show that calibrating the input parameters of a numerical model with the sole objective of improving fidelity to available measurements degrades the robustness of model predictions at both tested and untested settings. A more optimal model may be obtained by calibration methods considering both fidelity and robustness. Multi-criteria Decision Making further confirms the conclusion that the optimal model performance is achieved by maintaining a balance between fidelity and robustness during calibration.

Originality/value

Current methods for model calibration focus solely on fidelity while the authors focus on the trade-off between fidelity and robustness.

Details

Engineering Computations, vol. 32 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 July 2014

Fábio Ribeiro Soares da Cunha, Tobias Wille, Richard Degenhardt, Michael Sinapius, Francisco Célio de Araújo and Rolf Zimmermann

This paper aims to present a new robustness-based design strategy for thin-walled composite structures under compressive loading, which combines strength requirements in…

Abstract

Purpose

This paper aims to present a new robustness-based design strategy for thin-walled composite structures under compressive loading, which combines strength requirements in terms of the limit and ultimate load with robustness requirements evaluated from the structural energy until collapse.

Design/methodology/approach

In order to assess the structural energy, the area under the load-shortening curve between several characteristic points such as local buckling, global buckling, onset of degradation and collapse load is calculated. In this context, a geometrically nonlinear finite element analysis is carried out, in which the ply properties are selectively degraded by progressive failure.

Findings

The advantage of the proposed methodology is observed by analyzing unstiffened composite plates under compressive loading, wherein the lightest plate that satisfies both strength and robustness requirements can be attained.

Practical implications

As a practical implication, this methodology gives a new argument to accept the collapse load close to the ultimate load once robustness is ensured.

Originality value

The structural energy is employed to investigate the robustness of thin-walled composite structures in postbuckling, and new energy-based robustness measures are proposed. In the design of composite structures, this innovative strategy might lead to a more robust design when compared to an approach that only accounts for the ultimate load.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 86 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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