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Article

Abdul Kareem Lado and V.V. Singh

The purpose of this paper is to covenant with the cost assessment of a complex repairable system, consisting of two subsystems (Subsystem 1 and Subsystem 2) connected in…

Abstract

Purpose

The purpose of this paper is to covenant with the cost assessment of a complex repairable system, consisting of two subsystems (Subsystem 1 and Subsystem 2) connected in series configuration and being operated by a human operator. Each subsystem has two identical units in parallel configuration and has different types of failure and two types of repairs (general repair and copula repair). Through the transition diagram, the system of first-order partial differential equations is derived and solved using a supplementary variable technique, Laplace transforms. All failures are assumed to follow exponential distribution, whereas repairs follow two types of distributions that are general and Gumbel–Hougaard family copula. In this paper, explicit expressions for reliability, availability, mean time to failure (MTTF) and cost analysis functions have been obtained. In this paper, two types of repairs (copula repair and general repair) have been studied, and it has been concluded that copula repair is more reliable as compared to general repair. Some computations are taken as particular case by evaluating: reliability, availability, MTTF and cost analysis, so as to capture the effect of both failure and repair rates to reliability measures. The results have been shown in tables and graphs. The convincing part has been discussed in last section of this study.

Design/methodology/approach

This paper is focused on the cost assessment of a system consisting two subsystem series configuration. Each subsystem has two identical units in parallel configuration. The performance of the system has been analyzed by supplementary variable techniques and Laplace transforms. Various measures of the reliability have been discussed by evaluations. Software called Maple 13 is used for computations.

Findings

In this research paper, the authors have evaluated the operational cost and incurred profit of the system together with other reliability measures for various situations and different types of failures and two types of repairs using Gumbel–Hougaard family copula distribution.

Research limitations/implications

The present research focuses on the series and parallel configured complex systems that is used everywhere in industry and other sectors. The authors main aim is to claim that repair through the joint probability distribution copula is far better than general repair. Copula repair for a completely failed system is more beneficial for industrial system operations that will increase profit to the industrial sector.

Practical implications

The authors have observed that when repair follows general distribution the values of reliability obtained of the system are less compared to the those obtained when the authors apply copula repair, a joint probability distribution. It is a clear implication for industrial sector and organization to use the policy for a better generate revenue.

Social implications

According to the best of authors’ knowledge, there is no social implication as this study is meant for reliability section. The study in management and case study matters is considered to have social implication.

Originality/value

This research is the original work of authors. Nothing has been copied from any paper or book. The references are cited according to the relevance of study.

Details

International Journal of Quality & Reliability Management, vol. 36 no. 10
Type: Research Article
ISSN: 0265-671X

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Article

Remica Aggarwal, Surya Prakash Singh and P.K. Kapur

In this paper, vendor selection and order allocation problem is considered for a buyer dealing in multiple products to be supplied by multiple vendors. Each product has an…

Abstract

Purpose

In this paper, vendor selection and order allocation problem is considered for a buyer dealing in multiple products to be supplied by multiple vendors. Each product has an associated lead time with stochastic demand having stochastic capacity for each vendor across entire time period. Uncertainties related to costs which are further influenced by the periodically changing incremental quantity discounts offered by various vendors. The purpose of this paper is to find an optimal trade-off of vendor selection and order allocation in the presence of uncertainties involving multiple conflicting objectives such as cost minimization, service level/quality level maximization and delivery lead time minimization concurrently.

Design/methodology/approach

Vendor selection problem considered here has a multi-objective optimization design subject to a set of demand, capacity and quantity discount based constraints. These constraints as well as uncertainty related to lead time have been handled using chance constraint approach. The problem is titled as “integrated dynamic vendor selection problem (IDVSP).” The proposed multi-objective IDVSP is solved using both non-pre-emptive goal programming (GP) and weighted sum aggregate objective function (AOF) technique.

Findings

Findings indicate goal achievement for different objectives from both non-pre-emptive GP and AOF procedure. While the goals are satisfactorily achieved as per the target values for cost and lead time, quality/service level was somewhat compromised in order to find an appropriate trade off.

Originality/value

The research work is original as it integrates dynamic as well as stochastic (uncertain) nature of supply chain simultaneously coupled with the concept of incremental quantity discounts on lot sizes.

Details

Benchmarking: An International Journal, vol. 25 no. 3
Type: Research Article
ISSN: 1463-5771

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Article

V. V. Singh, Abubakkar Idris Mohhammad, Kabiru Hamisu Ibrahim and Ibrahim Yusuf

This paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers…

Abstract

Purpose

This paper analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The computed results are more supportable for repairable system performability analysis.

Design/methodology/approach

In this paper, the authors have analyzed a complex system consisting n-identical units under a k-out-of-n: G; configuration via a new method which has not been studied by previous researchers. The supplementary variable technique has employed for analyzing the performance of the system.

Findings

Reliability measures have been computed for different types of configuration. It generalized the results for purely series and purely parallel configurations.

Research limitations/implications

This research may be beneficial for industrial system performances whereas a k-out-of-n-type configuration exists.

Practical implications

Not sure as it is a theoretical assessment.

Social implications

This research may not have social implications.

Originality/value

This work is the sole work of authors that have not been communicated to any other journal before.

Details

International Journal of Quality & Reliability Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0265-671X

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Book part

Elisa Arcioni

The legal status of citizenship is constitutive in that it determines the boundaries of formal membership of a nation-state and, by implication, the lines of exclusion…

Abstract

The legal status of citizenship is constitutive in that it determines the boundaries of formal membership of a nation-state and, by implication, the lines of exclusion. The ways in which Australian law has defined membership over time – from subject status to citizen – provide a case study of the factors at play in understanding citizenship within a constitutional setting. We see that the constitution of citizenship may be a complex and unsettled evolutionary process.

Details

Law and the Citizen
Type: Book
ISBN: 978-1-80043-028-0

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Article

Rohollah Abdollahi

The purpose of this paper is to provide a T autotransformer based 12-pulse rectifier with passive harmonic reduction in more electric aircraft applications. The T…

Abstract

Purpose

The purpose of this paper is to provide a T autotransformer based 12-pulse rectifier with passive harmonic reduction in more electric aircraft applications. The T autotransformer uses only two main windings which result in volume, space, size, weight and cost savings. Also, the proposed unconventional inter-phase transformer (UIPT) with a lower kVA rating (about 2.6% of the load power) compared to the conventional inter-phase transformer results in a more harmonic reduction.

Design/methodology/approach

To increase rating and reduce the cost and complexity of a multi-pulse rectifier, it is well known that the pulse number must be increased. In some practical cases, a 12-pulse rectifier (12PR) is suggested as a good solution considering its simple structure and low weight. But the 12PR cannot technically meet the standards of harmonic distortion requirements for some industrial applications, and therefore, they must be used with output filters. In this paper, a 12PR is suggested, which consists of a T autotransformer 12PR and a passive harmonic reduction (PHR) based on the UIPT at direct current (DC) link.

Findings

To show the advantage of this new combination over other solutions, simulation results are used, and then, a prototype is implemented to evaluate and verify the simulation results. The simulation and experimental test results show that the input current total harmonic distortion (THD) of the suggested 12PR with a PHR based on UIPT is less than 5%, which meets the IEEE 519 requirements. Also, it is shown that in comparison with other solutions, it is cost effective, and at the same time, its power factor is near unity, and its rating is 29.92% of the load rating. Therefore, it is obvious that the proposed rectifier is a practical solution for more electric aircrafts.

Originality/value

The contributions of this paper are summarized as follows. The suggested design uses a retrofit T autotransformer, which meets all technical constraints, and in comparison, with other options, has less rating, weight, volume and cost. In the suggested rectifier, a PHR based on UIPT at its dc link of 12PR is used, which has good technical capabilities and lower ratings. In the PHR based on UIPT, an IPT is used, which has an additional secondary winding and four diodes. This solution leads to a reduction in input current THD and conduction losses of diodes. In full load conditions, the input line current THD and power factor are 4% and 0.99, respectively. The THD is less than 5%, which satisfies IEEE-519 and DO-160G requirements.

Details

Circuit World, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0305-6120

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Article

Fossy Mary Chacko, Ginu Ann George, Jayan M.V. and Prince A.

This paper aims to propose an improved multifunctional control strategy for achieving real, reactive power flow control and the mitigation of power quality issues in grid…

Abstract

Purpose

This paper aims to propose an improved multifunctional control strategy for achieving real, reactive power flow control and the mitigation of power quality issues in grid integrated photovoltaic (GIPV) systems.

Design/methodology/approach

The paper proposes a dual stage, three phase, multifunctional GIPV system with modified instantaneous reactive power (IRP) theory-based and modified synchronous reference frame (SRF) theory-based control algorithms for reference template generation with continuous load power requirement tracking. The control structure is designed so as to impart virtual distribution static compensator functionality to the photovoltaic inverter. The dual mode operation in active filter and renewable power injection modes provides enhanced capability to the GIPV system. A comprehensive evaluation of the dynamic behaviour of the GIPV system is carried out for various conditions of irradiance and load under MATLAB/Simulink platform. The performance comparison is done considering an uncompensated system and the GIPV system with both proposed control algorithms.

Findings

The extensive simulation results demonstrate that the proposed modified SRF theory-based multifunctional control strategy shows superior performance in real and reactive power flow control; reduction in real and reactive burden of the utility grid; and regulation of dc bus voltage under varying scenarios of irradiance and load. Furthermore, there is improvement of grid power factor and reduction in total harmonic distortion of grid currents in compliance with the IEEE 519 standard even with highly non-linear loads at the point of common coupling.

Originality/value

The proposed modified SRF theory-based multifunctional controller offers a viable solution for power quality enhancement as well as the realization of effective real and reactive power flow control in GIPV systems. Thus, the penetration level of distributed generation can be increased in this era of global energy crisis.

Details

World Journal of Engineering, vol. 17 no. 4
Type: Research Article
ISSN: 1708-5284

Keywords

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Article

Ayech Benjeddou and Mohamed Ali Hamdi

Presents a new B‐spline finite element for the dynamic analysis of unsymmetrical sandwich shells of revolution. The formulation takes account of the membrane and bending…

Abstract

Presents a new B‐spline finite element for the dynamic analysis of unsymmetrical sandwich shells of revolution. The formulation takes account of the membrane and bending effects in isotropic or orthotropic elastic facings, and membrane, bending and transverse shearing effects in an isotropic or othotropic elastic core. Both geometry and local displacements are interpolated by a set of B‐spline functions. The main aspects added by the sandwich structure of the element are the transverse shearing and membrane‐bending coupling effects in the core. These are well represented by a set of new variables which are the mean end relative in‐plane displacements of the facing middle surfaces. Together with the transverse displacement, these variables constitute the degrees of freedom (dofs) of this new B‐spline sandwich element. The finite elements are grouped into super‐elements with C1 continuity to obtain the whole finite element model. For each super‐element a total of five dofs per node is then obtained except for its end nodes where the derivatives of these dofs with respect to the meridional co‐ordinate are added. This choice reduces to a minimum the total number of dofs in comparison to existing sandwich elements. Evaluates the efficiency and accuracy of the proposed element through several benchmark examples. Compares the results with the analytical and numerical solutions found in the literature. A very satisfactory behaviour of the element was observed in all test cases.

Details

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

Keywords

Content available

Abstract

Details

Executive Burnout
Type: Book
ISBN: 978-1-78635-285-9

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Book part

Jitendra V. Singh

One area in which strategy and organizational ecology converge is organizational change. This essay weaves together salient themes in my (and my co-authors’) various…

Abstract

One area in which strategy and organizational ecology converge is organizational change. This essay weaves together salient themes in my (and my co-authors’) various writings on organizational change, and is anchored in the research literature of the last twenty years. Among other ideas developed here, I point out that there is now a convergence of agendas in strategy and ecology, with an important role being played by intraorganizational ecology. I develop the distinction between strong and weak selection approaches to organizational ecology. While the strong selection view does not find empirical support, there is stronger support for the weak selection view. I lay out some key features of an emerging evolutionary synthesis for the study of strategy and organization, and develop an evolutionary approach to organizational change.

Details

Ecology and Strategy
Type: Book
ISBN: 978-1-84950-435-5

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Article

Varinder Singh and Pravin M. Singru

The purpose of this paper is to propose the use of graph theoretic structural modeling for assessing the possible reduction in complexity of the work flow procedures in an…

Abstract

Purpose

The purpose of this paper is to propose the use of graph theoretic structural modeling for assessing the possible reduction in complexity of the work flow procedures in an organization due to lean initiatives. A tool to assess the impact of lean initiative on complexity of the system at an early stage of decision making is proposed.

Design/methodology/approach

First, the permanent function-based graph theoretic structural model has been applied to understand the complex structure of a manufacturing system under consideration. The model helps by systematically breaking it into different sub-graphs that identify all the cycles of interactions among the subsystems in the organization in a systematic manner. The physical interpretation of the existing quantitative methods linked to graph theoretic methodology, namely two types of coefficients of dissimilarity, has been used to evolve the new measures of organizational complexity. The new methods have been deployed for studying the impact of different lean initiatives on complexity reduction in a case industrial organization.

Findings

The usefulness and the application of new proposed measures of complexity have been demonstrated with the help of three cases of lean initiatives in an industrial organization. The new measures of complexity have been proposed as a credible tool for studying the lean initiatives and their implications.

Research limitations/implications

The paper may lead many researchers to use the proposed tool to model different cases of lean manufacturing and pave a new direction for future research in lean manufacturing.

Practical implications

The paper demonstrates the application of new tools through cases and the tool may be used by practitioners of lean philosophy or total quality management to model and investigate their decisions.

Originality/value

The proposed measures of complexity are absolutely new addition to the tool box of graph theoretic structural modeling and have a potential to be adopted by practical decision makers to steer their organizations though such decisions before the costly interruptions in manufacturing systems are tried on ground.

Details

Journal of Manufacturing Technology Management, vol. 29 no. 2
Type: Research Article
ISSN: 1741-038X

Keywords

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