Adam Mather, Raymond Cipra and Thomas Siegmund
Topologically interlocked materials are a class of materials in which individual unit elements interact with each other through contact only. Cracks and other defects occurring…
Abstract
Purpose
Topologically interlocked materials are a class of materials in which individual unit elements interact with each other through contact only. Cracks and other defects occurring due to external loading are contained in the individual unit elements. Thus, topologically interlocked materials are damage tolerant and provide high structural integrity. The purpose of this paper is to investigate the concepts of remanufacturing in the context of a material for which the intended use is structural such that the material's structural integrity is of concern. In particular, the study is concerned with the mechanical behavior of a topologically interlocked material.
Design/methodology/approach
A topologically interlocked material based on tetrahedron unit elements is investigated experimentally. Manufacturing with aid of a robotically controlled end‐effector is demonstrated, and mechanical properties are determined for a plate configuration. A conceptual mechanical model for failure of topologically interlocked materials is developed and used to interpret the experimental results.
Findings
It is demonstrated that remanufacturing of the topologically interlocked material is possible with only a limited loss of material performance. The proposed model predicts trends in agreement with the experimental findings.
Research limitations/implications
While the model predictions are qualitatively in agreement with experiments, more detailed finite element models are needed to predict the material performance accurately. Experiments were conducted on a model material obtained from a 3D printer and should be verified on other solids.
Practical implications
The authors demonstrate that damage containment together with the absence of binders or adhesives enables reuse through remanufacturing without loss of structural integrity.
Social implications
Topologically interlocked materials emerge as attractive materials for sustainable engineering once their material performance are weighted with an environmental impact factor.
Originality/value
Remanufacturing experiments on a novel class of materials were conducted and a new model for the characterization of the structural integrity of topologically interlocked materials is proposed and successfully evaluated against experiments in at least qualitative form.
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This paper gives a review of the finite element techniques (FE)applied in the area of material processing. The latest trends in metalforming, non‐metal forming and powder…
Abstract
This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming and powder metallurgy are briefly discussed. The range of applications of finite elements on the subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for the last five years, and more than 1100 references are listed.
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Tze Leung Lai and Haipeng Xing
This paper shows that volatility persistence in GARCH models and spurious long memory in autoregressive models may arise if the possibility of structural changes is not…
Abstract
This paper shows that volatility persistence in GARCH models and spurious long memory in autoregressive models may arise if the possibility of structural changes is not incorporated in the time series model. It also describes a tractable hidden Markov model (HMM) in which the regression parameters and error variances may undergo abrupt changes at unknown time points, while staying constant between adjacent change-points. Applications to real and simulated financial time series are given to illustrate the issues and methods.
Part II and last MECHETTI. Vienna FOUNDED in 1795 by Carlo Mechetti as a dealer; since 1807 in partnership with his nephew, Pietro; the publishing firm styled Carlo Mechetti &…
Abstract
Part II and last MECHETTI. Vienna FOUNDED in 1795 by Carlo Mechetti as a dealer; since 1807 in partnership with his nephew, Pietro; the publishing firm styled Carlo Mechetti & Neffe in 1809; after Carlo's death in 1811, Pietro became sole owner; he was succeeded in 1850 by his widow, Therese; c. 1855 the firm was taken over by A. Diabelli & co. (cp. Peter Cappi).
Mahour Mellat Parast and Elham (Ellie) H. Fini
This study aims to investigate the effect of productivity and quality on profitability in the US airline industry.
Abstract
Purpose
This study aims to investigate the effect of productivity and quality on profitability in the US airline industry.
Design/methodology/approach
Airlines operations and performance data were used to determine the effect of productivity and quality on profitability. Correlation and multivariate regression analysis have been used for data analysis.
Findings
The results show that labor productivity is the most significant predictor of profitability. On‐time performance has no relationship with profitability. The findings suggest that labor productivity, gas price, average annual maintenance cost and employee salary are significant predictors of profitability. The relationship between labor productivity and employee salary with profitability is positive, while gas price and average annual maintenance cost have a negative relationship with profitability.
Research limitations/implications
The research could be more detailed by taking into account measures of airline safety. Additional measures for service quality could be considered.
Practical implications
Operational performance (labor productivity) is the main source of profitability in the US airline industry followed by customer satisfaction and service quality.
Originality/value
The study captures the performance of the airline industry based on longitudinal data from 1989 to 2008. Previous studies have used either quarterly or monthly observations. Second, the study examines the significance of productivity and quality on profitability. Previous studies have provided little insight regarding the effect of productivity and quality on profitability.
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Jiang Wu, Xiao Huang and Bin Wang
To better understand the success of an open source software (OSS) project, this study aims to examine the role of social dependency networks (i.e. social and technical…
Abstract
Purpose
To better understand the success of an open source software (OSS) project, this study aims to examine the role of social dependency networks (i.e. social and technical dependencies) in online communities.
Design/methodology/approach
This study focuses on dependencies using three network metrics – degree centrality, betweenness centrality and closeness centrality – in developer and module networks. A longitudinal analysis from the projects hosted at Sourceforge.net is conducted to examine the effects of social and technical networks on the success of OSS projects. To address our research questions, we have constructed research models to investigate the social network effects in developer networks, the technical network effects in module networks, and the social-technical network effects in both types of networks.
Findings
The results reveal nonlinear relationships between degree centrality in both social and technical networks and OSS success, highlighting the importance of a moderate level of degree centrality in team structure and software architecture. Meanwhile, a moderate level of betweenness centrality and a lower level of closeness centrality between developers lead to a higher chance of OSS project success.
Originality/value
This study is the first attempt to consider the network metrics in both module networks of the technical sub-system and developer networks of the social sub-system to better understand their influences on project success.
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Abhishek Das and Gautam Sarkhel
The purpose of this paper is to study the effect of various stoichiometric ratios for synthesised epoxy phenolic novolac (EPN) resins on their physicochemical, thermomechanical…
Abstract
Purpose
The purpose of this paper is to study the effect of various stoichiometric ratios for synthesised epoxy phenolic novolac (EPN) resins on their physicochemical, thermomechanical and morphological properties.
Design/methodology/approach
In the present study, EPN (EPN-1, EPN-2, EPN-3, EPN-4 and EPN-5) resins were synthesised by varying five types of different stoichiometric ratios for phenol/formaldehyde along with the corresponding molar ratios for novolac/epichlorohydrin. Their different physicochemical properties of interest, thermomechanical properties as well as morphological properties were studied by means of cured samples with the variation of its stoichiometric ratios.
Findings
The average functionality and reactivity of EPN resin can be controlled by controlling epoxy equivalence as well as cross-linking density upon its curing as all of these factors are internally correlated with each other.
Research limitations/implications
Epoxy resins are characterised by a three-membered ring known as the epoxy or oxirane group. The capability of the epoxy ring to react with a variety of substrates imparts versatility to the resin. However, these resins have a major drawback of low toughness, and they are also very brittle, which limits their application in products that require high impact and fracture strength.
Practical implications
Epoxy resins have been widely used as high-performance adhesives and matrix resins for composites because of their outstanding mechanical and thermal properties. Because of their highly cross-linked structure, the epoxy resin disables segmental movement, making them hard, and it is also notch sensitive, having very low fracture energy.
Social implications
Epoxy resin is widely used in industry as protective coatings and for structural applications, such as laminates and composites, tooling, moulding, casting, bonding and adhesives.
Originality/value
Systematic study has been done for the first time, as no exact quantitative stoichiometric data for the synthesis of EPN resin were available on the changes of its different properties. Thus, an optimised stoichiometric composition for the synthesis of the EPN resin was found.
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The use of social media is one of the new technological options that has been recommended as a potential new strategy for delivering high-quality, high-value cancer prevention and…
Abstract
Purpose
The use of social media is one of the new technological options that has been recommended as a potential new strategy for delivering high-quality, high-value cancer prevention and management services. Despite the increasing use of social media, little research has been done on the use of social media in brain tumors. Therefore, this systematic review aims to provide a comprehensive review of the use of social media in brain tumor research.
Design/methodology/approach
A systematic search was performed in PubMed, Scopus and Web of Science from inception to August 1, 2022. English full-text articles evaluating social media use, benefit or content in brain tumor were considered.
Findings
Sixteen documents satisfied the inclusion criteria and were included in the final analysis. Most of the included studies (n = 11/16) were conducted and published by researchers in the USA. In terms of social media platform, most studies focused on Twitter (8/16, 50%) and YouTube (8/16, 50%), followed by Facebook (6/16, 37.5%) and Instagram (4/16, 25%). Most studies (n = 7/12) analyzed the content of brain tumor information provided on social media, followed by patients’ use of social media (n = 3/12) and the quality of information on social media (n = 3/12). The other three articles also examined patient recruitment, crowdfunding and caregiver use of social media.
Practical implications
By identifying the use, benefits and content of social media platforms in different settings, patients, clinicians and policymakers can better benefit from harnessing the power of social media in different ways, leading to improved health-care services.
Originality/value
To the authors knowledge, this is the first study to systematically examine social media use, benefits and content status in brain tumors.