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Article
Publication date: 1 January 2006

A.N. Shuaib

The purpose of this paper is to develop a procedure for deciding on the limits of initial clearance to which tubesheet holes can be enlarged before replacement in heat exchanger…

437

Abstract

Purpose

The purpose of this paper is to develop a procedure for deciding on the limits of initial clearance to which tubesheet holes can be enlarged before replacement in heat exchanger maintenance.

Design/methodology/approach

An empirical model that relates the hardness of roller expanded tubes and ligaments to initial clearance is developed from experimental data to predict the extent of tolerable levels of over‐enlargement of tubesheet holes before the joint loses its structural integrity. The developed model serves as an additional criterion to decide whether to keep or discard a tubesheet having over‐enlarged holes during heat exchanger maintenance.

Findings

The current industrial criterion does not directly include the effect of material degradation for over‐enlarged holes. The empirical models indicate that both tubes and ligaments suffer strain hardenings. A new procedure is proposed to supplement the current industrial criterion.

Practical implications

The procedure will assist maintenance managers/engineers in deciding on the replacement of heat exchanger tubesheets. The combined criteria will have an impact on the cost of heat exchanger maintenance and plant downtime.

Originality/value

The procedure proposed in this paper adds to the industrial criterion another one that caters for the degradation in properties that the tube, tubesheet, and surrounding ligaments will be subjected to during roller expansion. In other words, it considers the strain hardening of the tube and tubesheet materials in setting the initial clearance between the tube and tubesheet that ensures adequate joint integrity.

Details

Journal of Quality in Maintenance Engineering, vol. 12 no. 1
Type: Research Article
ISSN: 1355-2511

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Article
Publication date: 1 November 1995

A. Raouf, S.O. Duffuaa and A.N. Shuaib

Statistical process control seeks to monitor the qualitycharacteristics stipulated in the product design specifications toassure that these are achieved by the operation…

581

Abstract

Statistical process control seeks to monitor the quality characteristics stipulated in the product design specifications to assure that these are achieved by the operation. Measuring devices are subject to variations but usually the possibility of obtaining fluctuating results is often neglected and the measurements provided by these devices are taken for granted as true values. Presents, briefly, process control and shows the interaction between process capability and measuring device error. Presents a model for determining process target limits which minimize cost of production taking into account measuring device variability. Provides a criterion for establishing optimal process capability as well.

Details

International Journal of Quality & Reliability Management, vol. 12 no. 8
Type: Research Article
ISSN: 0265-671X

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Article
Publication date: 1 March 1993

A. Raouf, Zulfiqar Ali and S.O. Duffuaa

Maintenance management consists of an aggregate effort to performmaintenance by effectively utilizing manpower and material through theapplication of standard procedures. It is a

977

Abstract

Maintenance management consists of an aggregate effort to perform maintenance by effectively utilizing manpower and material through the application of standard procedures. It is a complex and multifaceted task. An ever‐growing number of computerized maintenance management information systems are available on the market to facilitate this task. In order to install a computerized maintenance management system, a company has two options: either to buy or to develop such a system. Briefly describes the major functions of maintenance management and suggests an instrument to evaluate comparatively the available computerized maintenance management systems.

Details

International Journal of Operations & Production Management, vol. 13 no. 3
Type: Research Article
ISSN: 0144-3577

Keywords

Available. Open Access. Open Access
Book part
Publication date: 4 June 2021

Olusesan Ayodeji Makinde, Emmanuel Olamijuwon, Nchelem Kokomma Ichegbo, Cheluchi Onyemelukwe and Michael Gboyega Ilesanmi

Incidents of violence perpetrated through digital technology platforms or facilitated by these means have been reported, often in high-income countries. Very little scholarly…

Abstract

Incidents of violence perpetrated through digital technology platforms or facilitated by these means have been reported, often in high-income countries. Very little scholarly attention has been given to the nature of technology-facilitated violence and abuse (TFVA) across sub-Saharan Africa (SSA) despite an explosion in the use of various technologies. We conducted a literature review to identify and harmonize available data relating to the types of TFVA taking place in SSA. This was followed by an online survey of young adults through the SHYad.NET forum to understand the nature of TFVA among young adults in SSA. Our literature review revealed various types of TFVA to be happening across SSA, including cyberbullying, cyberstalking, trolling, dating abuse, image-based sexual violence, sextortion, and revenge porn. The results of our online survey revealed that both young men and women experience TFVA, with the most commonly reported TFVA being receiving unwanted sexually explicit images, comments, emails, or text messages. Female respondents more often reported repeated and/or unwanted sexual requests online via email or text message while male respondents more often reported experiencing violent threats. Respondents used various means to cope with TFVA including blocking the abuser or deleting the abused profile on social media.

Details

The Emerald International Handbook of Technology-Facilitated Violence and Abuse
Type: Book
ISBN: 978-1-83982-849-2

Keywords

Available. Open Access. Open Access
Article
Publication date: 30 September 2019

Andrea Mantelli, Marinella Levi, Stefano Turri and Raffaella Suriano

The purpose of this study is to demonstrate the potential of three-dimensional printing technology for the remanufacturing of end-of-life (EoL) composites. This technology will…

2893

Abstract

Purpose

The purpose of this study is to demonstrate the potential of three-dimensional printing technology for the remanufacturing of end-of-life (EoL) composites. This technology will enable the rapid fabrication of environmentally sustainable structures with complex shapes and good mechanical properties. These three-dimensional printed objects will have several application fields, such as street furniture and urban renewal, thus promoting a circular economy model.

Design/methodology/approach

For this purpose, a low-cost liquid deposition modeling technology was used to extrude photo-curable and thermally curable composite inks, composed of an acrylate-based resin loaded with different amounts of mechanically recycled glass fiber reinforced composites (GFRCs). Rheological properties of the extruded inks and their printability window and the conversion of cured composites after an ultraviolet light (UV) assisted extrusion were investigated. In addition, tensile properties of composites remanufactured by this UV-assisted technology were studied.

Findings

A printability window was found for the three-dimensional printable GFRCs inks. The formulation of the composite printable inks was optimized to obtain high quality printed objects with a high content of recycled GFRCs. Tensile tests also showed promising mechanical properties for printed GFRCs obtained with this approach.

Originality/value

The novelty of this paper consists in the remanufacturing of GFRCs by the three-dimensional printing technology to promote the implementation of a circular economy. This study shows the feasibility of this approach, using mechanically recycled EoL GFRCs, composed of a thermoset polymer matrix, which cannot be melted as in case of thermoplastic-based composites. Objects with complex shapes were three-dimensional printed and presented here as a proof-of-concept.

Details

Rapid Prototyping Journal, vol. 26 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 25 January 2019

Andreas Loukopoulos, Christos Vasilios Katsiropoulos and Spiros G. Pantelakis

The purpose of this paper is to quantify the environmental footprint and cost and thus compare different manufacturing scenarios associated with the production of aeronautical…

319

Abstract

Purpose

The purpose of this paper is to quantify the environmental footprint and cost and thus compare different manufacturing scenarios associated with the production of aeronautical structural components.

Design/methodology/approach

A representative helicopter canopy, i.e., canopy of the EUROCOPTER EC Twin Star helicopter described in Pantelakis et al. (2009), has been considered for the carbon footprint (life cycle energy and climate change impact analysis) along with the life cycle costing analysis. Four scenarios – combinations of different manufacturing technologies (autoclave and resin transfer molding (RTM)) and end-of-life treatment scenarios (mechanical recycling and pyrolysis) are considered.

Findings

Using the models developed the expected environmental and cost benefits by involving the RTM technique have been quantified. The environmental impact was expressed in terms of energy consumption and of Global Warming Potential-100. From an environmental standpoint, processing the canopy using the RTM technique leads to decreased energy demands as compared to autoclaving because of the shorter curing cycles exhibited from this technique and thus the less time needed. As far as the financial viability of both processing scenarios is concerned, the more steps needed for preparing the mold and the need for auxiliary materials increase the material and the labor cost of autoclaving as compared to RTM.

Originality/value

At the early design stages in aeronautics, a number of disciplines (environmental, financial and mechanical) should be taken into account in order to evaluate alternative scenarios (material, manufacturing, recycling, etc.). In this paper a methodology is developed toward this direction, quantifying the environmental and financial viability of different manufacturing scenarios associated with the production of aeronautical structures.

Details

International Journal of Structural Integrity, vol. 10 no. 3
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 7 August 2020

Ali Akbar Abbasian Arani and Reza Moradi

Using turbulators, obstacles, ribs, corrugations, baffles and different tube geometry, and also various arrangements of these components have a noticeable effect on the shell and…

215

Abstract

Purpose

Using turbulators, obstacles, ribs, corrugations, baffles and different tube geometry, and also various arrangements of these components have a noticeable effect on the shell and tube heat exchangers (STHEs) thermal-hydraulic performance. This study aims to investigate non-Newtonian fluid flow characteristics and heat transfer features of water and carboxyl methyl cellulose (H2O 99.5%:0.5% CMC)-based Al2O3 nanofluid inside the STHE equipped with corrugated tubes and baffles using two-phase mixture model.

Design/methodology/approach

Five different corrugated tubes and two baffle shapes are studied numerically using finite volume method based on SIMPLEC algorithm using ANSYS-Fluent software.

Findings

Based on the obtained results, it is shown that for low-mass flow rates, the disk baffle (DB) has more heat transfer coefficient than that of segmental baffle (SB) configuration, while for mass flow rate more than 1 kg/s, using the SB leads to more heat transfer coefficient than that of DB configuration. Using the DB leads to higher thermal-hydraulic performance evaluation criteria (THPEC) than that of SB configuration in heat exchanger. The THPEC values are between 1.32 and 1.45.

Originality/value

Using inner, outer or inner/outer corrugations (outer circular rib and inner circular rib [OCR+ICR]) tubes for all mass flow rates can increase the THPEC significantly. Based on the present study, STHE with DB and OCR+ICR tubes configuration filled with water/CMC/Al2O3 with f = 1.5% and dnp = 100 nm is the optimum configuration. The value of THPEC in referred case was 1.73, while for outer corrugations and inner smooth, this value is between 1.34 and 1.57, and for outer smooth and inner corrugations, this value is between 1.33 and 1.52.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 August 2019

Sara Jebbor, Abdellatif El Afia and Raddouane Chiheb

This paper aims to propose an approach by human and material resources combination to reduce hospitals crowding. Hospitals crowding is becoming a serious problem. Many research…

164

Abstract

Purpose

This paper aims to propose an approach by human and material resources combination to reduce hospitals crowding. Hospitals crowding is becoming a serious problem. Many research works present several methods and approaches to deal with this problem. However, to the best of the authors’ knowledge – after a deep reading of literature – in all the proposed approaches, human and material resources are studied separately while they must be combined (to a given number of material resources an optimal number of human resources must be assigned and vice versa) to reflect reality and provide better results.

Design/methodology/approach

Hospital inpatient unit is chosen as framework. This unit crowding reduction is carried out by its capacity increasing. Indeed, inpatient unit modeling is performed to find the adequate combinations of human and material resources numbers insuring this unit stability and providing optimal service rates. At first, inpatient unit is modeled using queuing networks and considering only two resources (beds and nurses). Then, the obtained service rate formula is improved by including other resources and parameters using Baskett, Chandy, Muntz and Palecios (BCMP) queuing networks. This work is applied to “Princess Lalla Meryem” hospital inpatient unit.

Findings

Results are patients’ average number reduction by an average (in each block) of three patients, patients’ average waiting time reduction by an average of 9.98 h and non-admitted patients (to inpatient wards) access percentage of 39.26 per cent on average.

Originality/value

Previous works focus their studies on either human resources or material resources. Only a few works study both resources types, but separately. The context of those studies does not meet the real hospital context (where human resources are combined with material resources). Therefore, the provided results are not very reliable. In this paper, an approach by human and material resources combination is proposed to increase inpatient unit care capacity. Indeed, this approach consists of developing inpatient unit service rate formula in terms of human and material resources numbers.

Details

International Journal of Pervasive Computing and Communications, vol. 15 no. 2
Type: Research Article
ISSN: 1742-7371

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Article
Publication date: 24 March 2022

Elavaar Kuzhali S. and Pushpa M.K.

COVID-19 has occurred in more than 150 countries and causes a huge impact on the health of many people. The main purpose of this work is, COVID-19 has occurred in more than 150…

137

Abstract

Purpose

COVID-19 has occurred in more than 150 countries and causes a huge impact on the health of many people. The main purpose of this work is, COVID-19 has occurred in more than 150 countries and causes a huge impact on the health of many people. The COVID-19 diagnosis is required to detect at the beginning stage and special attention should be given to them. The fastest way to detect the COVID-19 infected patients is detecting through radiology and radiography images. The few early studies describe the particular abnormalities of the infected patients in the chest radiograms. Even though some of the challenges occur in concluding the viral infection traces in X-ray images, the convolutional neural network (CNN) can determine the patterns of data between the normal and infected X-rays that increase the detection rate. Therefore, the researchers are focusing on developing a deep learning-based detection model.

Design/methodology/approach

The main intention of this proposal is to develop the enhanced lung segmentation and classification of diagnosing the COVID-19. The main processes of the proposed model are image pre-processing, lung segmentation and deep classification. Initially, the image enhancement is performed by contrast enhancement and filtering approaches. Once the image is pre-processed, the optimal lung segmentation is done by the adaptive fuzzy-based region growing (AFRG) technique, in which the constant function for fusion is optimized by the modified deer hunting optimization algorithm (M-DHOA). Further, a well-performing deep learning algorithm termed adaptive CNN (A-CNN) is adopted for performing the classification, in which the hidden neurons are tuned by the proposed DHOA to enhance the detection accuracy. The simulation results illustrate that the proposed model has more possibilities to increase the COVID-19 testing methods on the publicly available data sets.

Findings

From the experimental analysis, the accuracy of the proposed M-DHOA–CNN was 5.84%, 5.23%, 6.25% and 8.33% superior to recurrent neural network, neural networks, support vector machine and K-nearest neighbor, respectively. Thus, the segmentation and classification performance of the developed COVID-19 diagnosis by AFRG and A-CNN has outperformed the existing techniques.

Originality/value

This paper adopts the latest optimization algorithm called M-DHOA to improve the performance of lung segmentation and classification in COVID-19 diagnosis using adaptive K-means with region growing fusion and A-CNN. To the best of the authors’ knowledge, this is the first work that uses M-DHOA for improved segmentation and classification steps for increasing the convergence rate of diagnosis.

Details

Journal of Engineering, Design and Technology , vol. 22 no. 3
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 31 May 2022

Feiming Wang, Xing Gao, Shuliang Zang and Shuang Yue

The purpose of this paper is to investigate the tribological properties, antiwear mechanism and anticorrosion properties of two novel halogen-free borate ionic liquids (ILs) in…

95

Abstract

Purpose

The purpose of this paper is to investigate the tribological properties, antiwear mechanism and anticorrosion properties of two novel halogen-free borate ionic liquids (ILs) in 500 N base oil.

Design/methodology/approach

Different qualities of borate ILs were added to 500 N, and their tribological properties were tested on a four-ball machine. The tribological properties of the additives were evaluated by measuring the wear scar diameter (WSD) and average coefficient of friction. The antiwear and antifriction mechanism of ILs was analyzed by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS).

Findings

The corrosion degrees of the two borate ILs 1-butyl-3-octyl-imidazole bis(mandelato)-borate ([OBIM][BMB]) and 1-butyl-3-(3-methoxypropyl)-imidazole bis(mandelato)-borate ([MPBIM][BMB]) are 1b and 1a, respectively, suggesting that they both possess significant corrosion resistance and can effectively protect the steel surface. When the concentration of [OBIM][BMB] and [MPBIM][BMB] is 2.5 Wt.%, the friction coefficient of 500 N is reduced by 37.3% and 26.2%, respectively. According to the analysis of the thermo gravimetric analyzer curves, [OBIM][BMB] and [MPBIM][BMB] decomposed at 369.7°C and 374.3°C, respectively, indicate that two additives both can be applied in higher temperature condition. The results of XPS and scanning electron microscope (SEM) reveal that [OBIM][BMB] and [MPBIM][BMB] both can react with the steel surface, thereby forming chemical films composed of iron oxide, B2O3 and organic N-containing compounds.

Originality/value

Two new environmentally friendly borate ILs were synthesized and their tribological properties in 500 N base oil were investigated for the first time.

Details

Industrial Lubrication and Tribology, vol. 74 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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