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Article

Neelam Chantola and S.B. Singh

The purpose of this paper is to study various reliability measures like reliability, mean time to failure (MTTF) and sensitivity of transformer including different…

Abstract

Purpose

The purpose of this paper is to study various reliability measures like reliability, mean time to failure (MTTF) and sensitivity of transformer including different parameters of insulating oil/paper as health index.

Design/methodology/approach

The reliability characteristics of transformer incorporating different parameters of insulating oil as well as paper have been evaluated using Markov process incorporating Gumbel–Hougaard copula, Laplace transforms and supplementary variable technique. The parameters taken into consideration are breakdown voltage (BDV) and moisture content (MC) of both insulating oil and paper, and other parameters considered are interfacial tension (IFT), dissipation factor (DF), degree of polymerization (DOP) and furanic content (FC) for insulating oil and paper, respectively. By probability consideration and continuity influence, difference-differential equations have been obtained for the considered model.

Findings

Transition state probabilities, reliability, MTTF and sensitivity of the transformer corresponding to different parameters of insulating oil and paper have been evaluated with the help of aforementioned technique. Variations of reliability with respect to time along with the variations of MTTF and sensitivity have also been examined. Remarkable points during the study have also been pointed out.

Originality/value

Reliability characteristics of the transformer have been evaluated including two parameters: insulating oil and paper with the help of supplementary variable technique, considering two different types of repairs incorporating Gumbel–Hougaard family of copula unlike done earlier. Reliability, MTTF and sensitivity of transformer have been analyzed considering the parameters: BDV, MC, IFT and FC of insulating oil, and BDV, MC, DOP, DF of insulating paper.

Details

International Journal of Quality & Reliability Management, vol. 36 no. 6
Type: Research Article
ISSN: 0265-671X

Keywords

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Article

Pankaj Khatak and H.C. Garg

Hybrid journal bearing have long been used in machines requiring large load and high speed capacity operating under wide range of temperatures. Different compensating…

Abstract

Purpose

Hybrid journal bearing have long been used in machines requiring large load and high speed capacity operating under wide range of temperatures. Different compensating devices are used in for efficient operation of bearings. This paper aims to help in selection of optimum compensating device by evaluating the comparative performance of constant flow valve, capillary compensated and slot entry hybrid journal bearing under the combined influence of thermal effects and micropolar nature of lubricant.

Design/methodology/approach

The variation in micropolar parameters and viscosity change due to temperature increase of lubricant are considered in present study. Finite element method is used for combined iterative solution of micropolar Reynolds, energy and conduction equations. Micropolar lubricant is assumed to be governed by two parameters, coupling number and characteristic length. The results in the study are presented for symmetric and asymmetric configurations of hole entry and slot entry non-recessed hybrid journal bearings

Findings

The results indicate that constant flow valve compensated hole entry hybrid journal bearing is the highest performing bearing for the given range of micropolar parameters of lubricant in terms of maximum fluid pressure and dynamic coefficients.

Originality/value

The performance variations of various configurations of hybrid journal bearing are presented in a single paper. The reader can get overview of combined effects of micropolar parameters and viscosity decrease due to temperature increase of the lubricant.

Details

Industrial Lubrication and Tribology, vol. 70 no. 6
Type: Research Article
ISSN: 0036-8792

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Article

Pentyala Srinivasa Rao and Amit Kumar Rahul

This paper aims to investigate the effect of surface roughness (radial and azimuthal) and viscosity variation on a squeeze film of a conical bearing with a non-Newtonian…

Abstract

Purpose

This paper aims to investigate the effect of surface roughness (radial and azimuthal) and viscosity variation on a squeeze film of a conical bearing with a non-Newtonian lubricant by using Rabinowitsch fluid model.

Design/methodology/approach

The main objective is to determine the stochastic nonlinear modified Reynolds equation for rough conical bearing. Later, first-order closed-form solutions are obtained using a small perturbation method and are numerically solved using the Gauss quadrature method.

Findings

The findings of this paper, numerical calculations, are analyzed for pressure, load carrying capacity and response time. The simulated results indicate that the influence of surface roughness increases the pressure, load carrying capacity and response time, whereas the viscosity variation factor decreases the pressure, load and response time.

Originality/value

According to both types of surface roughness with viscosity variation, the performance of a squeeze film rough conical bearing was improved by using Rabinowitsch fluid model. As it is inevitable to consider viscosity variation for bearing designer, it leads to a long life period of conical bearing.

Details

Industrial Lubrication and Tribology, vol. 71 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Jay P. Singh, Rabeea Assy and Katrina I. Serpa

The purpose of this paper is to explore the violence risk assessment practices in Israel by social workers, clinical criminologists, and marriage and family therapists…

Abstract

Purpose

The purpose of this paper is to explore the violence risk assessment practices in Israel by social workers, clinical criminologists, and marriage and family therapists using a Web-based survey.

Design/methodology/approach

A Web-based survey and participation letter were translated into Hebrew and distributed to members of the Israel Association of Social Workers, the Israel Society of Clinical Criminology and the Israel Association for Marital and Family Therapy following the Dillman Total Design Survey Method.

Findings

The sample was composed of 34 professionals, who reported using structured instruments to predict and manage the likelihood of violence in over half of their risk assessments over both their lifetime and the past 12 months. Younger female respondents who entered their profession more recently were more likely to use instruments during the risk assessment process. There appeared to be a trend toward decreased use of actuarial instruments and increased use in structured professional judgment instruments.

Originality/value

The first national survey of violence risk assessment practices by behavioral healthcare professionals in Israel was conducted. This study revealed the risk assessment utility trends in Israel, finding that compared to professionals in North America, South America, Europe, East Asia and Australia, professionals in Israel conducted fewer risk assessments and used structured instruments less often, highlighting concern about the lack of reliance on evidence-based techniques in the country.

Details

Journal of Aggression, Conflict and Peace Research, vol. 11 no. 2
Type: Research Article
ISSN: 1759-6599

Keywords

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Article

Luis Conde-López, Guillermo Gutiérrez-Alcaraz and S.N. Singh

Long-term reliability analysis of generation capacity based on the forecasted load demand helps to identify the optimal generation expansion plan of the system. This paper…

Abstract

Purpose

Long-term reliability analysis of generation capacity based on the forecasted load demand helps to identify the optimal generation expansion plan of the system. This paper analyzes the generation adequacy of Mexico’s National Interconnected Power System (MNIPS) using loss of load expectation (LOLE) and loss of energy expectation (LOEE) indices.

Design/methodology/approach

These indices are calculated through an analytical (recursive) method and are then compared with values recommended by the North American Electric Reliability Council (NERC). Weekly indices are computed to analyze the load curtailment options that may occur in some periods.

Findings

Forecasted values, including load and generation capacity considering maintenance schedules, additions of new generating units and permanently shut down units in accordance with the long-term expanding-system plan have been considered. The load forecast uncertainty is also included.

Originality/value

This is original work.

Details

International Journal of Energy Sector Management, vol. 10 no. 4
Type: Research Article
ISSN: 1750-6220

Keywords

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Article

Paul F. Takac and C.P. Singh

Defines the concept of strategic alliances as well as outlining thepotential benefits and disadvantages of entering into suchrelationships. This will facilitate critical…

Abstract

Defines the concept of strategic alliances as well as outlining the potential benefits and disadvantages of entering into such relationships. This will facilitate critical reviews of the nature and type of relationship that best satisfies their individual needs. Strategic alliances are a means of rationalizing business operations and improving the overall competitive position of a company and are important because of the sheer speed and dynamism of technological change which has opened up a wide range of new activity areas. Banking firms, however, experienced difficulty in defining the type of relationship that best suits their needs. To a significant extent this is due to the fact that a great deal of confusion exists regarding the term “strategic alliances”. In particular parties have difficulty in distinguishing strategic alliances from other forms of organizational relationships.

Details

Management Decision, vol. 30 no. 1
Type: Research Article
ISSN: 0025-1747

Keywords

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Article

Parlad Kumar Garg, Rupinder Singh and IPS Ahuja

The purpose of this paper is to optimize the process parameters to obtain the best dimensional accuracy, surface finish and hardness of the castings produced by using…

Abstract

Purpose

The purpose of this paper is to optimize the process parameters to obtain the best dimensional accuracy, surface finish and hardness of the castings produced by using fused deposition modeling (FDM)-based patterns in investment casting (IC).

Design/methodology/approach

In this paper, hip implants have been prepared by using plastic patterns in IC process. Taguchi design of experiments has been used to study the effect of six different input process parameters on the dimensional deviation, surface roughness and hardness of the implants. Analysis of variance has been used to find the effect of each input factor on the output. Multi-objective optimization has been done to find the combined best values of output.

Findings

The results proved that the FDM patterns can be used successfully in IC. A wax coating on the FDM patterns improves the surface finish and dimensional accuracy. The improved dimensional accuracy, surface finish and hardness have been achieved simultaneously through multi-objective optimization.

Research limitations/implications

A thin layer of wax is used on the plastic patterns. The effect of thickness of the layer has not been considered. Further research is needed to study the effect of the thickness of the wax layer.

Practical implications

The results obtained by the study would be helpful in making decisions regarding machining and/or coating on the parts produced by this process.

Originality/value

In this paper, multi-objective optimization of dimensional accuracy, surface roughness and hardness of hybrid investment cast components has been performed.

Details

Rapid Prototyping Journal, vol. 23 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

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Article

PETER E.D. LOVE, ZAHIR IRANI, EDDIE CHENG and HENG LI

The construction industry is highly fragmented and adversarial in nature, which has resulted in it being criticized for its poor project performance and lack of…

Abstract

The construction industry is highly fragmented and adversarial in nature, which has resulted in it being criticized for its poor project performance and lack of innovation. To improve performance, particularly inter‐organizational relations, organizations need to consider the formation of alliances with their project partners. Some construction organ‐ izations are beginning to initiate short‐term alliances with their customers and suppliers as part of a supply chain management strategy. However, such short‐term alliances inhibit feedback, which in turn supports learning and the development of mutual trust and cooperation. It is proffered that construction organizations should consider developing long‐term alliances, so as to enable parties to form learning alliances. The implications of forming different types of strategic alliances/partnering in construction are discussed. An inter‐organizational model that can be used to support learning and is founded on the principles of total quality management (TQM) is described. A case study is used to demonstrate that cooperative relationships can be used to cultivate a culture for reflective learning and mutual trust, beyond merely project‐specific performance improvements.

Details

Engineering, Construction and Architectural Management, vol. 9 no. 1
Type: Research Article
ISSN: 0969-9988

Keywords

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Article

Anish Sachdeva, Dinesh Kumar and Pradeep Kumar

This paper aims to propose a methodology based on Petri nets to evaluate the reliability characteristics of the pulping system of a paper industry in a realistic working…

Abstract

Purpose

This paper aims to propose a methodology based on Petri nets to evaluate the reliability characteristics of the pulping system of a paper industry in a realistic working environment. The effects of occurrence of failure/course of actions and availability of repair facilities on system performance have been investigated.

Design/methodology/approach

Stochastic Reward Nets (SRN), an extension of Petri nets, are applied to model the interactions among the active/standby units of the system and reliability parameters have been evaluated using Monte Carlo simulation.

Findings

The methodology adopted in this paper provides a better understanding of the behavior of the system under varying operating conditions. Reliability analysis of a pulping system of a paper industry presented in this paper will help the management in deciding upon the maintenance strategy to be adopted to improve the performance of the system and consequently reduce the operation and maintenance cost.

Originality/value

The application of the proposed technique will not only help the reliability engineers/managers/system engineers to understand the dynamic behavior of complex systems but also helps to plan/adapt suitable maintenance policies to improve system reliability/availability.

Details

International Journal of Quality & Reliability Management, vol. 25 no. 8
Type: Research Article
ISSN: 0265-671X

Keywords

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Book part

Paul Gill, Zoe Marchment, Sanaz Zolghadriha, Nadine Salman, Bettina Rottweiler, Caitlin Clemmow and Isabelle Van Der Vegt

Purpose – This chapter provides a roadmap for future research and evaluation on violent extremist risk analysis.Methodology/Approach – The authors synthesize the lessons…

Abstract

Purpose – This chapter provides a roadmap for future research and evaluation on violent extremist risk analysis.

Methodology/Approach – The authors synthesize the lessons learned from process evaluations of general violence risk assessment, bias research, survey designs, linguistic analyses, and spatial analyses, and apply them to the problem of violent extremist risk assessment and management.

Findings – The next generation of violent extremist risk assessment research will necessitate a focus upon process, barriers to effective implementation and taking the human element of decision-making into account. Furthermore, the development of putative risk factors for violent extremist attitudes and behaviors necessitates a movement toward more survey-based research designs. Future risk assessment processes may additionally take language and spatial components into account for a more holistic understanding.

Originality/Value – Based on existing literature, there is a paucity of research conducting process evaluations, survey designs, linguistic analyses, and spatial analyses in this area. The authors provide several roadmaps, assessments of respective strengths and weaknesses, and highlight some initial promising results.

Details

Radicalization and Counter-Radicalization
Type: Book
ISBN: 978-1-83982-988-8

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