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Article
Publication date: 1 October 2019

Balaraju Jakkula, Govinda Raj M. and Murthy Ch.S.N.

Load haul dumper (LHD) is one of the main ore transporting machineries used in underground mining industry. Reliability of LHD is very significant to achieve the expected targets…

495

Abstract

Purpose

Load haul dumper (LHD) is one of the main ore transporting machineries used in underground mining industry. Reliability of LHD is very significant to achieve the expected targets of production. The performance of the equipment should be maintained at its highest level to fulfill the targets. This can be accomplished only by reducing the sudden breakdowns of component/subsystems in a complex system. The identification of defective component/subsystems can be possible by performing the downtime analysis. Hence, it is very important to develop the proper maintenance strategies for replacement or repair actions of the defective ones. Suitable maintenance management actions improve the performance of the equipment. This paper aims to discuss this issue.

Design/methodology/approach

Reliability analysis (renewal approach) has been used to analyze the performance of LHD machine. Allocations of best-fit distribution of data sets were made by the utilization of Kolmogorov–Smirnov (K–S) test. Parametric estimation of theoretical probability distributions was made by utilizing the maximum likelihood estimate (MLE) method.

Findings

Independent and identical distribution (IID) assumption of data sets was validated through trend and serial correlation tests. On the basis of test results, the data sets are in accordance with IID assumption. Therefore, renewal process approach has been utilized for further investigation. Allocations of best-fit distribution of data sets were made by the utilization of Kolmogorov–Smirnov (K–S) test. Parametric estimation of theoretical probability distributions was made by utilizing the MLE method. Reliability of each individual subsystem has been computed according to the best-fit distribution. In respect of obtained reliability results, the reliability-based preventive maintenance (PM) time schedules were calculated for the expected 90 percent reliability level.

Research limitations/implications

As the reliability analysis is one of the complex techniques, it requires strategic decision making knowledge for the selection of methodology to be used. As the present case study was from a public sector company, operating under financial constraints the conclusions/findings may not be universally applicable.

Originality/value

The present study throws light on this equipment that need a tailored maintenance schedule, partly due to the peculiar mining conditions, under which they operate. This study mainly focuses on estimating the performance of four numbers of well-mechanized LHD systems with reliability, availability and maintainability (RAM) modeling. Based on the drawn results, reasons for performance drop of each machine were identified. Suitable recommendations were suggested for the enhancement of performance of capital intensive production equipment. As the maintenance management is only the means for performance improvement of the machinery, PM time intervals were estimated with respect to the expected rate of reliability level.

Details

Journal of Quality in Maintenance Engineering, vol. 26 no. 2
Type: Research Article
ISSN: 1355-2511

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Article
Publication date: 22 July 2020

Balaraju Jakkula, Govinda Raj Mandela and Murthy Ch S N

In the present worldwide situation, the survival of a business is a major crucial aspect. The business cannot be succeeded unless it produces the anticipated production levels…

919

Abstract

Purpose

In the present worldwide situation, the survival of a business is a major crucial aspect. The business cannot be succeeded unless it produces the anticipated production levels. Achievement of this can be possible only by maintaining the equipment into an adequate level. Load-Haul-Dumpers (LHDs), as the main workhorse and massive transporting machines, are highly utilized in underground mining operations. Despite the usage of LHDs, these are prone to the uneven and unexpected occurrence of potential failures. These are causes to minimize the production and productivity of capital intensive equipment. To get a good profitability index, it is very necessary to have the required levels of equipment reliability and availability. Estimation of reliabilities and availabilities play a critical role in the performance evaluation of equipment.

Design/methodology/approach

By keeping the significance of the present research work in view in this research paper one of the well appropriate techniques such as fault tree analysis (FTA) was utilized to assess the reliability of the LHD system based on the function flow diagram. Best fit distribution of data sets were made by the utilization of Kolmogorov–Smirnov (K-S) test. Parametric estimation of theoretical probability distributions was done by utilizing the maximum likelihood estimation (MLE). Failure rate of each LHD system has computed based on the best fit results from “Isograph Reliability Workbench 13.0”. Reliability configuration of each LHD system has modeled using reliability block diagram (RBD), as well as the FTA.

Findings

Independent and identical distribution (IID) assumption of data sets was validated through statistic U-test (Chi Squared test). On the basis of test results, the data sets are in accordance with IID assumption. Therefore renewal process approach has been utilized for further investigation. Allocations of best fit distribution of data sets were made by the utilization ofK-S test. Parametric estimation of theoretical probability distributions was made by utilizing maximum likelihood estimation (MLE) method. Reliability of each individual subsystem has been computed according to the best fit distribution. The deductive method called RBD was utilized to investigate the given system reliability by analyzing with graphical representations of logic system and observed highest percentage of reliability as 69.44% (LH29). FTA has been utilized to investigate the availability percentage of a system and observed highest percentage value as 79.51% (LH29). This technique also helps to identify the most critical parts/cut sets by using Fussell-Vesely (F-V) importance measure.

Research limitations/implications

As the reliability analysis is one of the complex techniques, it requires strategic decision-making knowledge for the selection of methodology to be used. As the present case study was from a public sector company, operating under financial constraints the conclusions/findings may not be universally applicable.

Originality/value

The present study throws light on this equipment that need a tailored maintenance schedules, partly due to the peculiar mining conditions, under which they operate. This analysis provides the information on several aspects such as present working condition of the machines, occurrence of various potential failure modes, influence of failure modes on its performance and reliable life aspects etc. Also, these investigations asses the forecasting of necessary managerial practices or control measures like possible design modifications and replacement actions of components to ensure the required levels of availability and utilization of the equipment. Both qualitative and quantitative analysis of FTA has been performed to determine the minimal/most influencing cut sets of the system and to estimate overall system availability within the work environment. Based on the computed results reasons for performance drop of each machine was identified and suitable recommendations were suggested to improve the performance of capital intensive systems.

Details

International Journal of Quality & Reliability Management, vol. 38 no. 3
Type: Research Article
ISSN: 0265-671X

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Article
Publication date: 5 August 2022

Monika Saini, Deepak Sinwar, Alapati Manas Swarith and Ashish Kumar

Reliability and maintainability estimation of any system depends on the identification of the best-fitted probability distribution of failure and repair rates. The parameters of…

210

Abstract

Purpose

Reliability and maintainability estimation of any system depends on the identification of the best-fitted probability distribution of failure and repair rates. The parameters of the best-fitted probability distribution are also contributing significantly to reliability estimation. In this work, a case study of load haul dump (LHD) machines is illustrated that consider the optimization of failure and repair rate parameters using two well established metaheuristic approaches, namely, genetic algorithm (GA) and particle swarm optimization (PSO). This paper aims to analyze the aforementioned points.

Design/methodology/approach

The data on time between failures (TBF) and time to repairs (TTR) are collected for a LHD machine. The descriptive statistical analysis of TBF & TTR data is performed, trend and serial correlation tested and using Anderson–Darling (AD) value best-fitted distributions are identified for repair and failure times of various subsystems. The traditional methods of estimation like maximum likelihood estimation, method of moments, least-square estimation method help only in finding the local solution. Here, for finding the global solution two well-known metaheuristic approaches are applied.

Findings

The reliability of the LHD machine after 60 days on the real data set is 28.55%, using GA on 250 generations is 17.64%, and using PSO on 100 generations and 100 iterations is 30.25%. The PSO technique gives the global best value of reliability.

Practical implications

The present work will be very convenient for reliability engineers, researchers and maintenance managers to understand the failure and repair pattern of LHD machines. The same methodology can be applied in other process industries also.

Originality/value

In this case study, initially likelihood function of the best-fitted distribution is optimized by GA and PSO. Reliability and maintainability of LHD machines evaluated by the traditional approach, GA and PSO are compared. These results will be very helpful for maintenance engineers to plan new maintenance strategies for better functioning of LHD machines.

Details

Journal of Quality in Maintenance Engineering, vol. 29 no. 2
Type: Research Article
ISSN: 1355-2511

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Book part
Publication date: 30 May 2018

Albert A. Okunade, Xiaohui You and Kayhan Koleyni

The search for more effective policies, choice of optimal implementation strategies for achieving defined policy targets (e.g., cost-containment, improved access, and quality…

Abstract

The search for more effective policies, choice of optimal implementation strategies for achieving defined policy targets (e.g., cost-containment, improved access, and quality healthcare outcomes), and selection among the metrics relevant for assessing health system policy change performance simultaneously pose continuing healthcare sector challenges for many countries of the world. Meanwhile, research on the core drivers of healthcare costs across the health systems of the many countries continues to gain increased momentum as these countries learn among themselves. Consequently, cross-country comparison studies largely focus their interests on the relationship among health expenditures (HCE), GDP, aging demographics, and technology. Using more recent 1980–2014 annual data panel on 34 OECD countries and the panel ARDL (Autoregressive Distributed Lag) framework, this study investigates the long- and short-run relationships among aggregate healthcare expenditure, income (GDP per capita or per capita GDP_HCE), age dependency ratio, and “international co-operation patents” (for capturing the technology effects). Results from the panel ARDL approach and Granger causality tests suggest a long-run relationship among healthcare expenditure and the three major determinants. Findings from the Westerlund test with bootstrapping further corroborate the existence of a long-run relationship among healthcare expenditure and the three core determinants. Interestingly, GDP less health expenditure (GDP_HCE) is the only short-run driver of HCE. The income elasticity estimates, falling in the 1.16–1.46 range, suggest that the behavior of aggregate healthcare in the 34 OECD countries tends toward those for luxury goods. Finally, through cross-country technology spillover effects, these OECD countries benefit significantly from international investments through technology cooperations resulting in jointly owned patents.

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Book part
Publication date: 17 February 2020

Simon Grima and Eleftherios I. Thalassinos

Abstract

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Financial Derivatives: A Blessing or a Curse?
Type: Book
ISBN: 978-1-78973-245-0

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Article
Publication date: 1 October 1998

Marilyn Domas White

This article characterises the questioning behaviour in reference interviews preceding delegated online searches of bibliographic databases and relates it to questioning behaviour…

3105

Abstract

This article characterises the questioning behaviour in reference interviews preceding delegated online searches of bibliographic databases and relates it to questioning behaviour in other types of interviews/settings. With one exception, the unit of analysis is the question (N=610), not the interview. The author uses A.C. Graesser‘s typology of questions to analyse type of question and M.D. White’s typology of information categories to determine the question‘s content objective; this is the first application of Graesser’s typology to interview questions in any setting. Graesser‘s categories allow for a more subtle understanding of the kind of information need underlying a question. Comparisons are made between questions asked by the information specialist and those asked by the client. Findings show that the information specialist dominates the interview, about half the questions were verification questions and about 22% were judgemental questions or requests; all but four types of questions from Graesser’s categories appeared in the interviews, but no new question types were discovered. Clients often phrase questions as requests. In content, both clients and information specialists focus on the subject and service requested, but the clients ask also about search strategy and output features. Both parties ask predominantly short‐answer questions. Results are related to interface design for retrieval systems.

Details

Journal of Documentation, vol. 54 no. 4
Type: Research Article
ISSN: 0022-0418

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Article
Publication date: 1 August 2004

George K. Chacko

Case Studies generally ask: (1) What accounts for the success/failure of this real‐life “Case” (Corporation, Government or Organization)?; (2) How can we transport the lessons…

1465

Abstract

Case Studies generally ask: (1) What accounts for the success/failure of this real‐life “Case” (Corporation, Government or Organization)?; (2) How can we transport the lessons learned across time and space?; (3) What immediate/eventual issue/objective(s) should the “Case” pursue to enhance its survival/success; and How? The student is graded on the Case Study by the force of his/her reasoning and arguments, two diametrically‐opposite action plans both scoring “A”. But which one should the CEO implement? Why? Are there minimal criteria that any Case Study of management should fulfill? The raison d etre of management is the pre‐committing of scarce resources for unknown/unknowable results (e.g., market share, mind share), which are generated by interactions of variables and/or participants. Does the Case Study identify the cogent interactions; does it suggest how to allocate resources to achieve pre‐specified results? This Case Study has been checked by the corporation for accuracy. We structure the narrative by systems theory which provides a framework to assess what the company has achieved, and to formulate what it should do to improve its chances of survival/success. The theory is buttressed by illustrations of systems approach to complexity, ranging from Apollo lunar landing to the $91‐billion IT Services Company, IBM. According to National Association of Software and Services Companies (NASSCOM), exports rose 30.5 per cent to $12.5 billion in Fiscal Year 2003‐04 ending on March 31, 2004 from $9.6 billion in Fiscal 2002‐. Indian exports totaled $52.72 billion in 2003‐04. Applying the growth in the first five months, we estimate the total exports in 2003‐04 at $54.8 billion. The IT exports contributed 18.2 per cent in 2002‐03, rising to 22.8 per cent in 2003‐04.

Details

Management Research News, vol. 27 no. 8/9
Type: Research Article
ISSN: 0140-9174

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Article
Publication date: 22 May 2008

Raymond Viskanta

This paper seeks to review the literature on methods for solving the radiative transfer equation (RTE) and integrating the radiant energy quantities over the spectrum required to…

1076

Abstract

Purpose

This paper seeks to review the literature on methods for solving the radiative transfer equation (RTE) and integrating the radiant energy quantities over the spectrum required to predict the flow, the flame and the thermal structures in chemically reacting and radiating combustion systems.

Design/methodology/approach

The focus is on methods that are fast and compatible with the numerical algorithms for solving the transport equations using the computational fluid dynamics techniques. In the methods discussed, the interaction of turbulence and radiation is ignored.

Findings

The overview is limited to four methods (differential approximation, discrete ordinates, discrete transfer, and finite volume) for predicting radiative transfer in multidimensional geometries that meet the desired requirements. Greater detail in the radiative transfer model is required to predict the local flame structure and transport quantities than the global (total) radiation heat transfer rate at the walls of the combustion chamber.

Research limitations/implications

The RTE solution methods and integration of radiant energy quantities over the spectrum are assessed for combustion systems containing only the infra‐red radiating gases and gas particle mixtures. For strongly radiating (i.e. highly sooting) and turbulent flows the neglect of turbulence/radiation interaction may not be justified.

Practical implications

Methods of choice for solving the RTE and obtaining total radiant energy quantities for practical combustion devices are discussed.

Originality/value

The paper has identified relevant references that describe methods capable of accounting for radiative transfer to simulate processes arising in combustion systems.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 3/4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 4 August 2021

Atin Sumihartati, Wiah Wardiningsih, Naelly Al Kautsar, Muhammad Permana, Samuel Pradana and Ryan Rudy

The purpose of this study is to explore the potential of Cordyline Australis fibers as an alternate raw material for textile.

174

Abstract

Purpose

The purpose of this study is to explore the potential of Cordyline Australis fibers as an alternate raw material for textile.

Design/methodology/approach

The water retting method was used to extract the fiber. Cordyline Australis fibers were characterized in terms of the morphology of fibers (fiber cross-sectional and longitudinal), fiber chemical functional groups, tensile strength and elongation, fineness, fiber length, moisture regain and friction coefficient.

Findings

Cordyline Australis fiber strands consist of several individual fibers. At the longitudinal section, the fiber cells appeared as long cylindrical tubes with a rough surface. The cross-section of the Cordyline Australis fibers was irregular but some were oval. The key components in the fibers were cellulose, hemicellulose and lignin. The tensile strength of the fiber per bundle was 2.5 gf/den. The elongation of fibers was 13.15%. The fineness of fiber was 8.35 Tex. The average length of the fibers was 54.72 cm. Moisture Regain for fiber was 8.59%. The friction coefficient of fibers was 0.16. The properties of the fiber showed that the Cordyline Australis fiber has the potential to be produced into yarn.

Originality/value

To the best of the author's knowledge, there is no scientific article focused on the Cordyline Australis fibers. Natural fibers from the leaves of the Cordyline Australis plant could be used as an alternate material for textile.

Details

Research Journal of Textile and Apparel, vol. 26 no. 3
Type: Research Article
ISSN: 1560-6074

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Article
Publication date: 1 January 1992

ZHI‐HUA ZHONG and JAROSLAV MACKERLE

Contact problems are among the most difficult ones in mechanics. Due to its practical importance, the problem has been receiving extensive research work over the years. The finite…

563

Abstract

Contact problems are among the most difficult ones in mechanics. Due to its practical importance, the problem has been receiving extensive research work over the years. The finite element method has been widely used to solve contact problems with various grades of complexity. Great progress has been made on both theoretical studies and engineering applications. This paper reviews some of the main developments in contact theories and finite element solution techniques for static contact problems. Classical and variational formulations of the problem are first given and then finite element solution techniques are reviewed. Available constraint methods, friction laws and contact searching algorithms are also briefly described. At the end of the paper, a bibliography is included, listing about seven hundred papers which are related to static contact problems and have been published in various journals and conference proceedings from 1976.

Details

Engineering Computations, vol. 9 no. 1
Type: Research Article
ISSN: 0264-4401

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