D. Balzani, D. Böse, D. Brands, R. Erbel, A. Klawonn, O. Rheinbach and J. Schröder
The purpose of this paper is to present a computational framework for the simulation of patient‐specific atherosclerotic arterial walls. Such simulations provide information…
Abstract
Purpose
The purpose of this paper is to present a computational framework for the simulation of patient‐specific atherosclerotic arterial walls. Such simulations provide information regarding the mechanical stress distribution inside the arterial wall and may therefore enable improved medical indications for or against medical treatment. In detail, the paper aims to provide a framework which takes into account patient‐specific geometric models obtained by in vivo measurements, as well as a fast solution strategy, giving realistic numerical results obtained in reasonable time.
Design/methodology/approach
A method is proposed for the construction of three‐dimensional geometrical models of atherosclerotic arteries based on intravascular ultrasound virtual histology data combined with angiographic X‐ray images, which are obtained on a routine basis in the diagnostics and medical treatment of cardiovascular diseases. These models serve as a basis for finite element simulations where a large number of unknowns need to be calculated in reasonable time. Therefore, the finite element tearing and interconnecting‐dual primal (FETI‐DP) domain decomposition method is applied, to achieve an efficient parallel solution strategy.
Findings
It is shown that three‐dimensional models of patient‐specific atherosclerotic arteries can be constructed from intravascular ultrasound virtual histology data. Furthermore, the application of the FETI‐DP domain decomposition method leads to a fast numerical framework. In a numerical example, the importance of three‐dimensional models and thereby fast solution algorithms is illustrated by showing that two‐dimensional approximations differ significantly from the 3D solution.
Originality/value
The decision for or against intravascular medical treatment of atherosclerotic arteries strongly depends on the mechanical situation of the arterial wall. The framework presented in this paper provides computer simulations of stress distributions, which therefore enable improved indications for medical methods of treatment.
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This paper deals with the optimization of coal handling system performability for a thermal power plant.
Abstract
Purpose
This paper deals with the optimization of coal handling system performability for a thermal power plant.
Design/methodology/approach
Coal handling system comprises of five subsystems, namely Wagon Tippler, Crusher, Bunker, Feeder and Coal Mill. The partial differential equations are derived on the behalf of transition diagram by using the Markov approach. These partial differential equations are further solved to obtain the performance model with the help of normalization condition. Numerous performability levels are achieved by putting the appropriate combinations of failure and repair rates (FRRs) in performance model. Performability optimization for coal handling system is obtained by varying the population and generation size.
Findings
Highest performability level, that is, 93.33 at population size of 40 and 93.31 at generation size of 70, is observed.
Originality/value
The findings of this paper highlight the optimum value of performability level and FRRs for numerous subsystems. These findings are highly beneficial for plant administration to decide about the maintenance planning.
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The purpose of this paper is to analyze a thermal power plant (TPP) by taking into consideration its key components, namely, boiler, turbine, conveyor and generator, which are…
Abstract
Purpose
The purpose of this paper is to analyze a thermal power plant (TPP) by taking into consideration its key components, namely, boiler, turbine, conveyor and generator, which are handled by a human operator. It is well known fact that the continuous power generation through a power plant depends on the reliability/availability of its components.
Design/methodology/approach
The various performance measures of a TPP are obtained by using mathematical modeling, Markov process and supplementary variable technique.
Findings
Reliability, i.e. mean time to failure with respect to different components of a TPP, has been obtained and demonstrated with the help of graphs. Critical components of the system are identified through sensitivity analysis.
Originality/value
In the present paper, a mathematical model based on the functioning of a TPP has been developed. Conclusions in this paper are good references for the design of a TPP.
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Internal migration has grown intensively in India in the present decades, far greater than international migration, though the latter has received far more attention in literature…
Abstract
Purpose
Internal migration has grown intensively in India in the present decades, far greater than international migration, though the latter has received far more attention in literature and public policy. Among internal migrants, seasonal movement is another growing phenomenon in India which has received the least attention till now. The purpose of the study is to show the intensities of short-term morbidity and major morbidity among the rural and urban internal migrants and how such disease burdens have affected the health of regular/permanent and temporary/seasonal migrants.
Design/methodology/approach
This present paper has been developed on the basis of data of India Human Development Survey-II (IHDS-II), 2011–2012, has been availed to find out the intensities of short-term morbidity and major morbidity among the rural and urban migrants as well as the health condition of the seasonal migrants. For the analysis of regular or permanent migrants, a total of 3,288 migrants (of which 1,136 rural migrants and 2,152 urban migrants) were surveyed in IHDS-II, 2011–2012, regarding the persistence of different types of short-term morbidity among the migrant class. Two-sample (rural migrants and urban migrants) “t” test for mean difference with unequal variances with null hypothesis – H0: diff = 0, and alternate hypothesis – Ha: diff < 0; Ha: diff > 0 where diff = mean (rural) – mean (urban) has been executed. For the seasonal migrants a sample of 41,424 migrants of which 2,691 seasonal migrant workers and 38,733 non-seasonal migrant workers were surveyed in IHDS-II, 2011–2012, to find out their health condition. OLS regression on the number of medical treatments undertaken in a month on the nature of migrant workers has been conducted. Socio-economic factors (like adult literacy) and basic amenities required for a healthy living (like indoor piped drinking water, separate kitchen in the household, household having a flush toilet, household having electricity and intake of meals everyday) are taken as control variables in the regression analysis.
Findings
The results of morbidity analysis in this paper show that the morbidity patterns among the migrants vary with the geographical differences. The short-term morbidity and that of the major morbidity show different proneness to ill health for rural and urban migrants. However, seasonal migrants are more susceptible to ill health than the regular migrants and are also potential for generating health risks. Also lack of provision of basic services creates negative health impact on seasonal migrants.
Research limitations/implications
The paper is based on secondary data and hence lacks numerous relevant health issues of migrants in rural and urban sectors which could have been possible through primary data survey.
Practical implications
Migration and migrants are a relevant issue both internationally and nationally. Economic development of a country like India depends to a greater extent on the contributions of migrant labourers as majority of the labourers in India belong to informal sector of which most of the workers are from migrant class.
Social implications
Migrants contribution to economic development depend on their productive capacity and hence health of these section of people is a relevant issue. This study is based on the morbidity pattern of migrants both regular and seasonal migrants and their susceptibility in various geographical locations and provision of basic amenities.
Originality/value
This work is original research study by the author.
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The present paper investigated a skim milk powder production plant with genuine human mistake for analyzing its performance in terms of its reliability, availability and…
Abstract
Purpose
The present paper investigated a skim milk powder production plant with genuine human mistake for analyzing its performance in terms of its reliability, availability and maintainability (RAM) indices along with mean time between failure (MTBF) and expected number of failure (ENOF).
Design/methodology/approach
In the proposed work, the generalized fuzzy lambda–tau methodology has been used to carry out the analysis of the repairable structure using the improved arithmetic operations for generalized fuzzy numbers by considering the degree of confidence levels.
Findings
RAM indices along with MTBF and ENOF are obtained to increase the quality of skim milk powder manufacturing structures of a dairy plant with genuine human-mistake working conditions.
Originality/value
In the present paper, a mathematical model for a complex industrial system based on fuzzy has been developed. Finally, the results are more realistic and comprehensive for the decision-maker for farther application.
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Nan Li, M. Prabhu and Atul Kumar Sahu
The main purpose of present study is to model the replacement policy under uncertainty for managerial application based on grey-reliability approach by considering the subjective…
Abstract
Purpose
The main purpose of present study is to model the replacement policy under uncertainty for managerial application based on grey-reliability approach by considering the subjective views of quality control circle (QCC). The study objectively links the optimality between individual replacement and group replacement policies for determining the minimum operational costs. The integrated framework between QCC, replacement theory, grey set theory and supply chain management is presented to plan replacement actions under uncertainty.
Design/methodology/approach
The study proposes the concept of grey-reliability index and built a decision support model, which can deal with the imprecise information for determining the minimum operational costs to plan subsequent maintenance efforts.
Findings
The findings of the study establish the synergy between individual replacement and group replacement policies. The computations related to the numbers of failures, operational costs, reliability index and failure probabilities are presented under developed framework. An integrated framework to facilitate the managers in deciding the replacement policy based on operational time towards concerning replacement of assets that do not deteriorate, but fails suddenly over time is presented. The conceptual model is explained with a numerical procedure to illustrate the significance of the proposed approach.
Originality/value
A conceptual model under the framework of such items, whose failures cannot be corrected by repair actions, but can only be set by replacement is presented. The study provides an important knowledge based decision support framework for crafting a replacement model using grey set theory. The study captured subjective information to build decision model in the ambit of replacement.
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Anil Aggarwal, Sanjeev Kumar and Vikram Singh
The purpose of this paper is to propose a method to compute RAMD indices to measure and improve the performance of skim milk powder production system of a dairy plant under real…
Abstract
Purpose
The purpose of this paper is to propose a method to compute RAMD indices to measure and improve the performance of skim milk powder production system of a dairy plant under real working conditions.
Design/methodology/approach
The present work is carried out by developing performance model based on Markov birth-death process. The skim milk powder production system consists of six units. The first order governing differential equations are derived using the mnemonic rule and further solved to calculate RAMD indices i.e. reliability, availability, maintainability, dependability, MTBF, MTTR and dependability ratio for each subsystem of the system.
Findings
The subsystem SS1 comprising of chiller and cream separator is the most critical from maintenance point of view, as the reliability, availability, maintainability, dependability, MTBF and dependability ratio indices are low as compared to those of other subsystems of skim milk powder production system of the dairy plant.
Originality/value
The RAMD indices of the present work is very useful for finding the critical subsystem and its effect on the performance of the system working under real working conditions. Further, based on findings the maintenance priorities for various subsystems can be decided.
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Nilesh Pancholi and Mangal Bhatt
The purpose of this paper is to investigate the extent at which the reliability of an aluminium wire rolling mill can be improved by ameliorating current control and maintenance…
Abstract
Purpose
The purpose of this paper is to investigate the extent at which the reliability of an aluminium wire rolling mill can be improved by ameliorating current control and maintenance practices.
Design/methodology/approach
The paper deals with the discrimination of the most critical components by substantial shop-floor failure data. The research work narrates a method for evaluating maintainability criticality index for each failure cause of identified critical components through two different MCDM approaches: one based on grey-complex proportional risk assessment (COPRAS-G) and the other based on preference section index (PSI).
Findings
The primary findings of this research work are to prioritize the maintenance activities by comparing results obtained through different failure analysis models. It is proposing improvements in the maintenance plan of critical components like bearings, gears and shafts of an aluminium wire rolling mill which are commonly representing the most critical components in a large range of industrial processes.
Research limitations/implications
The limitation of the proposed study is that the failure models may not represent failures due to the first instant every time as adequate of design as such components are not checked for a high failure rate.
Practical implications
The proposed study is an interdisciplinary work which will help to understand about the working lives of components and associated failures. It will lead to reengineer new tools efficiently and to gain the maintenance excellence.
Originality/value
Originality mainly consists in the contemporary application of two non-identical MCDM-based methods (COPRAS-G and PSI). It will help to elucidate maintenance issues of major process industries and recommended deliverable keys.