Search results

The article addresses the optimization of safety stock service levels for parts in a repair kit. The work was undertaken to assist a public transit entity that stores thousands of parts used to repair equipment acquired over many decades. Demand is intermittent, procurement lead times are long, and the total inventory investment is significant.

Demand exists for repair kits, and a repair cannot start until all required parts are available. The cost model includes holding cost to carry the part being modeled as well as shortage cost that consists of the holding cost to carry all other repair kit parts for the duration of the part’s lead time. The model combines deterministic and stochastic approaches by assuming a fixed ordering cycle with Poisson demand.

The results show that optimal service levels vary as a function of repair demand rate, part lead time, and cost of the part as a percentage of the total part cost for the repair kit. Optimal service levels are higher for inexpensive parts and lower for expensive parts, although the precise levels are impacted by repair demand and part lead time.

The proposed model can impact society by improving the operational performance and efficiency of public transit systems, by ensuring that home repair technicians will be prepared for repair tasks, and by reducing the environmental impact of electronic waste consistent with the right-to-repair movement.

The optimization model is unique because (1) it quantifies shortage cost as the cost of unnecessary holding other parts in the repair kit during the shortage time, and (2) it determines a unique service level for each part in a repair kit bases on its lead time, its unit cost, and the total cost of all parts in the repair kit. Results will be counter-intuitive for many inventory managers who would assume that more critical parts should have higher service levels.

This paper aims to develop a specific type of mobile nonrigid support friction stir welding (FSW) robot, which can adapt to aluminum alloy trucks for rapid online repair.

The friction stir welding robot is designed to complete online repair according to the surface damage of large aluminum alloy trucks. A rotatable telescopic arm unit and a structure for a cutting board in the shape of a petal that was optimized by finite element analysis are designed to give enough top forging force for welding to address the issues of inadequate support and significant deformation in the repair process.

The experimental results indicate that the welding robot is capable of performing online surface repairs for large aluminum alloy trucks without rigid support on the backside, and the welding joint exhibits satisfactory performance.

Compared with other heavy-duty robotic arms and gantry-type friction stir welding robots, this robot can achieve online welding without disassembling the vehicle body, and it requires less axial force. This lays the foundation for the future promotion of lightweight equipment.

The designed friction stir welding robot is capable of performing online repairs without dismantling the aluminum alloy truck body, even in situations where sufficient upset force is unavailable. It ensures welding quality and exhibits high efficiency. This approach is considered novel in the field of lightweight online welding repairs, both domestically and internationally.

This study provides an analysis of patch repair for cracked aircraft structures. Delamination is a type of damage that affects the patch's behavior. The purpose of this study is to assess the influence of delamination on repair performance.

An analytical and numerical study using the finite element method was conducted for a cracked plate repaired with a patch containing a pre-existing delamination defect. The method for defining the contact pair surfaces and modeling the delamination interaction within the patch interface is specified using the virtual crack closure technique (VCCT) approach.

The efficiency of the repair is measured in terms of the J-integral. The effects of delamination initiation, mechanical loading, crack length and patch stacking sequences are presented. It is noted that in mode I, delamination propagation is only significant at node A. The numerical results are in good agreement with those of the analytical solution found in the literature. It is observed that the patch's behavior is strongly dependent on loading, crack size and stacking sequences in terms of reducing the structure's lifespan, especially in the presence of delamination.

The numerical modeling presented by the VCCT approach is highly valuable for studying delamination evolution. The influence of loading, crack size and stacking sequences on repair performance is discussed in this work.

At the end of the session, learners are expected to be able to evaluate the detrimental impact of stress on blue-collar workers’ well-being in Attainer Engineering Sdn Bhd; develop effective strategies to improve stressful conditions experienced by blue-collar workers in Attainer Engineering Sdn Bhd; analyse and select appropriate approaches that can help maintain the motivation levels of blue-collar workers in Attainer Engineering Sdn Bhd; analyse the impact of Attainer Engineering Sdn Bhd’s extensive investment in training new blue-collar workers, alongside the subsequent high turnover rate, on the decline in sales and profit; identify the critical changes that the managing director should have implemented to prioritize employee retention among blue-collar workers at Attainer Engineering Sdn Bhd; discuss the strategic implementation of mechanization, specifically in the context of automating repetitive processes, as an innovative solution to address the challenges faced by the ship repair and maintenance service industry heavily reliant on blue-collar workers in emerging markets; cultivate thoughtful debates on ways to keep blue-collar workers in the shipping repair and maintenance industry, as well as active learner participation and group interaction; develop learners’ analytical and critical thinking skills by guiding them through the analysis of a real-world case study in the shipping repair and maintenance industry, concentrating on the difficulties and potential solutions for blue-collar worker retention; and equip learners with practical knowledge and insights on implementing effective human resources strategies for retaining blue-collar workers in the shipping repair and maintenance industry, emphasizing the conversion of theoretical concepts into workable solutions.

This teaching case study centres on Attainer Engineering Sdn Bhd, a Malaysian conglomerate that bestows ship repair and maintenance services. Regrettably, the corporation has been subjected to a decrease in profitability and productivity owing to its high turnover rate of blue-collar workers. The ship repair and maintenance service industry is accountable for delivering comprehensive repair and maintenance services to ships, including their engines, hulls, machinery and other related components. The fundamental aim of this case study is to ascertain the rudimentary factors that contribute to this issue and foster effective strategies to enhance the motivation and retention rate of blue-collar workers in the ship repair and maintenance service corporation, using appropriate management theories, models and concepts. The case study brings to light the importance of discovering the most suitable approaches to retain blue-collar workers in the corporation to improve its profitability and productivity in a highly competitive market. This teaching case study will be beneficial for students and practitioners who want to grasp the disputes associated with retaining blue-collar workers in the ship repair and maintenance service industry and learn how to apply management theories, models and concepts to address these disputes effectively.

This case discussion would be highly suitable for undergraduate and postgraduate university students who are pursuing their studies in management or related fields and are eager to delve into the nuances of the ship repair and maintenance service industry. Furthermore, trainers from both private and public agencies who are keen on gaining a deeper understanding of the issues pertaining to retaining blue-collar workers in this particular industry and devising result-oriented strategies to tackle these concerns would also find this case discussion immensely helpful.

Teaching notes are available for educators only.

CSS 6: Human resource management.

The primary objective of this study is to tackle the enduring challenge of preserving feature integrity during the manipulation of geometric data in computer graphics. Our work aims to introduce and validate a variational sparse diffusion model that enhances the capability to maintain the definition of sharp features within meshes throughout complex processing tasks such as segmentation and repair.

We developed a variational sparse diffusion model that integrates a high-order L₁ regularization framework with Dirichlet boundary constraints, specifically designed to preserve edge definition. This model employs an innovative vertex updating strategy that optimizes the quality of mesh repairs. We leverage the augmented Lagrangian method to address the computational challenges inherent in this approach, enabling effective management of the trade-off between diffusion strength and feature preservation. Our methodology involves a detailed analysis of segmentation and repair processes, focusing on maintaining the acuity of features on triangulated surfaces.

Our findings indicate that the proposed variational sparse diffusion model significantly outperforms traditional smooth diffusion methods in preserving sharp features during mesh processing. The model ensures the delineation of clear boundaries in mesh segmentation and achieves high-fidelity restoration of deteriorated meshes in repair tasks. The innovative vertex updating strategy within the model contributes to enhanced mesh quality post-repair. Empirical evaluations demonstrate that our approach maintains the integrity of original, sharp features more effectively, especially in complex geometries with intricate detail.

The originality of this research lies in the novel application of a high-order L₁ regularization framework to the field of mesh processing, a method not conventionally applied in this context. The value of our work is in providing a robust solution to the problem of feature degradation during the mesh manipulation process. Our model’s unique vertex updating strategy and the use of the augmented Lagrangian method for optimization are distinctive contributions that enhance the state-of-the-art in geometry processing. The empirical success of our model in preserving features during mesh segmentation and repair presents an advancement in computer graphics, offering practical benefits to both academic research and industry applications.

This paper aims to study a circular economy business model that offers services with embedded information exchange capabilities to extend product life through maintenance and repair. Information exchange has been identified as a critical factor in advancing the principles of a circular economy, and this research was conducted to illustrate how information exchange can facilitate maintenance and repair.

The study has a case study approach of collecting data through semi-structured interviews and questionnaires.

Information exchange on what and when to do something engages end-users in maintenance and facilitates learning. For repair, the problem description and possible solutions are information that must be exchanged. Both types of information exchange are facilitated by simple tech solutions relying on known and inexpensive technology (e.g. e-mail service, video call and text messaging).

The study contributes to the organisational development and knowledge management fields with novel insights on how information exchange and circular economy are related and can be facilitated.

The study provides insights for companies looking for solutions on how to generate revenue from services and reduce resource consumption. The findings of the study suggest that the development of circular business models does not always require expensive high-tech solutions.

To the best of the authors’ knowledge, this study is unique as it is empirically based on insights into how information exchange can extend product life through the use of simple digital tools.

This paper aims to investigate the experimental behavior and the reliability of concrete columns repaired using fiber-reinforced polymers (FRPs) under axial compression loading. The expression of the ultimate axial resistance was assessed from the experimental data of damaged concrete cylinders repaired by externally bonded double-FRP spiral strips.

The tested columns bearing capacity mainly depends of the elasticity modulus of both damaged and undamaged concrete have been considered in addition to the applied load and the cylinder diameter as random variables in the expression of the failure criterion. The reliability indicators were assessed using first order second moment method.

The emphasized test results, statistically fitted show that the strength has been retrofitted for all repaired specimens whatever the degree of initial damage. However, the gain in axial strength is inversely proportional to the degree of damage.

The efficiency of a new FRP repair procedure using double-spiral strips was studied. This research provides a technical and economical solution for retrofitting existing concrete columns. Finally, the random character of the variables that govern the studied system shows the accuracy and safety of the proposed original design.

This study argues that online user comments on social media platforms provide feedback and evaluation functions. These functions can provide services for the relevant departments of organizations or institutions to formulate corresponding public opinion response strategies.

This study considers Chinese universities’ public opinion events on the Weibo platform as the research object. It collects online comments on Chinese universities’ network public opinion governance strategy texts on Weibo, constructs the sentiment index based on sentiment analysis and evaluates the effectiveness of the network public opinion governance strategy adopted by university officials.

This study found the following: First, a complete information release process can effectively improve the effect of public opinion governance strategies. Second, the effect of network public opinion governance strategies was significantly influenced by the type of public opinion event. Finally, the effect of public opinion governance strategies is closely related to the severity of punishment for the subjects involved.

The theoretical contribution of this study lies in the application of image repair theory and strategies in the field of network public opinion governance, which further broadens the scope of the application of image repair theory and strategies.

This study expands online user comment research to network public opinion governance and provides a quantitative method for evaluating the effect of governance strategies.

The peer review history for this article is available at: https://publons.com/publon/10.1108/OIR-05-2022-0269

While steady-state analysis is useful, it does not consider the inherent transient characteristics of repairable systems' behavior, especially in systems that have relatively short life spans, or when their transient behavior is of special concern such as the motivating example used in this paper, military systems. Therefore, a maintenance policy that considers both transient and steady-state availability and aims to achieve the best trade-off between high steady-state availability and rapid stabilization is essential.

This paper studies the transient behavior of system availability under the Kijima Type II virtual age model. While such systems achieve steady-state availability, and it has been proved that deploying preventive maintenance (PM) can significantly improve its steady-state availability, this improvement often comes at the price of longer and increased fluctuating transient behavior, which affects overall system performance. The authors present a methodology that identifies the optimal PM policy that achieves the best trade-off between high steady-state availability and rapid stabilization based on cost-availability analysis.

When the proposed simulation-based optimization and cost analysis methodology is applied to the motivating example, it produces an optimal PM policy that achieves an availability–variability balance between transient and steady-state system behaviors. The optimal PM policy produces a notably lower availability coefficient of variation (by 11.5%), while at the same time suffering a negligible limiting availability loss of only 0.3%. The new optimal PM policy also provides cost savings of about 5% in total maintenance cost. The performed sensitivity analysis shows that the system's optimal maintenance cost is sensitive to the repair time, the shape parameter of the Weibull distribution and the downtime cost, but is robust with respect to changes in the remaining parameters.

Most of the current maintenance models emphasize the steady-state behavior of availability and neglect its transient behavior. For some systems, using steady-state availability as the sole metric for performance is not adequate, especially in systems that have relatively short life spans or when their transient behavior affects the overall performance. However, little work has been done on the transient analysis of such systems. In this paper, the authors aim to fill this gap by emphasizing such systems and applications where transient behavior is of critical importance to efficiently optimize system performance. The authors use military systems as a motivating example.

Relationships have changed dramatically in the last 50 years. Fewer couples are marrying, more are cohabiting. Reasons for this shift include more attractive labor market opportunities for women and changing social norms, but the shift may have consequences of its own. A number of models predict that those cohabiting will specialize less than those marrying. Panel data on time use – particularly housework time – as well as on the degree of specialization in more narrowly defined household tasks from the 2001–2019 waves of the Household, Income and Labour Dynamics in Australia survey are used to test this prediction.

The time use data for men provides only limited supporting evidence for specialization. The results for women are much stronger. Women who marry without first cohabiting increase their reported housework time more than those who enter cohabitations (by 3.7 hours versus 1.2 hours). The latter generally make up a third of the difference if they do marry. Expanding the analysis to other uses of time yields some further evidence of specialization.

Survey responses on the degree of specialization are more informative. The raw data show substantial intrahousehold specialization and further analysis reveals that on average married couples specialize more than cohabiting couples. Adding couple-specific fixed effects reveals that specialization increases when cohabiting couples marry. Interestingly, there does not appear to be a substantial tradeoff between tasks; partners who report specializing more on one task are more likely to report specializing on other tasks as well. Given the important roles couples have in family formation and the labor market, it is important to understand this intrahousehold behavior.