A Model for Maintenance Planning and Process Quality Control Optimization Based on EWMA and CUSUM Control Charts

The performance of a production system is highly dependent on the smooth operation of various equipment and processes. Thus, reducing failures of the equipment and processes in a cost-effective manner improves overall performance; this is often achieved by carrying out maintenance and quality control policies. In this study, an integrated optimization method that addresses both maintenance strategies and quality control practices is proposed using an exponentially weighted moving average (EWMA) chart, in which both corrective and preventive maintenance policies are considered. The integrated model has been proposed to find optimal decision variables of both the process quality decision parameters and the optimal interval of preventive maintenance (i.e., Ns, Hs, L, λ, and t_PM) to result in overall optimal expected hourly total system costs. A case study is then utilized to investigate the impact of cost criteria on the proposed integrated model and to compare the proposed model with a model using the cumulative sum (CUSUM) control chart. The improved model outputs indicate that there is a reduction of 34.6% in the total expected costs compared with those of the other model using the CUSUM chart. Finally, an analysis of sensitivity to present the effectiveness of the model parameters and the main variables in the overall costs of the system is provided

Confusion Control in Generalized Petri Nets Using Synchronized Events

The loss of conflicting information in a Petri net (PN), usually called confusions, leads to incomplete and faulty system behavior. Confusions, as an unfortunate phenomenon in discrete event systems modeled with Petri nets, are caused by the frequent interlacement of conflicting and concurrent transitions. In this paper, confusions are defined and investigated in bounded generalized PNs. A reasonable control strategy for conflicts and confusions in a PN is formulated by proposing elementary conflict resolution sequences (ECRSs) and a class of local synchronized Petri nets (LSPNs). Two control algorithms are reported to control the appeared confusions by generating a series of external events. Finally, an example of confusion analysis and control in an automated manufacturing system is presented

The Role Of EI In Effective Leadership, In The Context Of Saudi Arab: A Systematic Review

Background: The field of Emotional Intelligence (EI) is a growing field reflecting its effectiveness in different professions and institutes. There is little evidence available to seek a comprehensive role of EI in effective leadership. This study explores the role of EI in effective leadership. Aim: The aim of this study is to investigate how the component of EI plays an effective role in leadership, in the context of Saudi Arab. Method: For the purpose, a systematic approach was employed to identify and select relevant studies from key databases. Inclusion and exclusion criteria ensured the consideration of studies published within 05 years that examined the role of EI for effective leadership. Data extraction and analysis were conducted to synthesize findings from 11 selected studies. Results: In total 130 articles were explored and only 03 were found very relevant and 28 somewhat relevant based on inclusion criteria. Findings revealed that EI play a key role in any field specifically in effective leadership and leadership skills including empathy, self-management, and self-awareness. However, limitations including selection bias were acknowledged. Conclusion: The study concludes that EI can enhance the leadership role and can bring very significant advancement in the field of leadership. Since, there was no studies found that studied exclusively EI in relation with effective leadership

Evaluation of Support Structure Removability for Additively Manufactured Ti6Al4V Overhangs via Electron Beam Melting

The addition of support structures is essential for the successful fabrication of overhang structures through additive manufacturing (AM). The support structures protect the overhang portion from distortions. They are fabricated with the functional parts and are removed later after the fabrication of the AM part. While structures bearing insufficient support result in defective overhangs, structures with excessive support result in higher material consumption, time and higher post-processing costs. The objective of this study is to investigate the effects of design and process parameters of support structures on support removability during the electron beam melting (EBM)-based additive manufacturing of the Ti6Al4V overhang part. The support design parameters include tooth parameters, no support offset, fragmentation parameters and perforation parameters. The EBM process parameters consist of beam current, beam scan speed and beam focus offset. The results show that both support design and process parameters have a significant effect on support removability. In addition, with the appropriate selection of design and process parameters, it is possible to significantly reduce the support removal time and protect the surface quality of the part

A Multidisciplinary Approach in the Treatment of Tempromandibular Joint Pain Associated with Qat Chewing

Pain of the tempro-mandibular joint (TMJ) has a direct bearing to missing teeth and excessive physical activity. Consumption of qat requires chewing on the leaves to extract their juice for long hours. A 65-year-old male Yemeni patient, a Qat chewer, reported to the university dental hospital at King Khalid University complaining of pain in left temporomandibular joint with missing mandibular anterior teeth. A multidisciplinary approach for the overall treatment of the patient was decided. Initial treatment was the relief of patient’s pain with the help of a night guard. This was followed by a fabrication of anterior FPD. The case was under maintenance and follow-up protocol for a period of 8 months with no complaint of pain discomfort

Assessment of finite element and smoothed particles hydrodynamics methods for modeling serrated chip formation in hardened steel

This study aims to perform comparative analyses in modeling serrated chip morphologies using traditional finite element and smoothed particles hydrodynamics methods. Although finite element models are being employed in predicting machining performance variables for the last two decades, many drawbacks and limitations exist with the current finite element models. The problems like excessive mesh distortions, high numerical cost of adaptive meshing techniques, and need of geometric chip separation criteria hinder its practical implementation in metal cutting industries. In this study, a mesh free method, namely, smoothed particles hydrodynamics, is implemented for modeling serrated chip morphology while machining AISI H13 hardened tool steel. The smoothed particles hydrodynamics models are compared with the traditional finite element models, and it has been found that the smoothed particles hydrodynamics models have good capabilities in handling large distortions and do not need any geometric or mesh-based chip separation criterion

Requirements of the Smart Factory System: A Survey and Perspective

With the development of Industry 4.0 and the emergence of the smart factory concept, the traditional philosophy of manufacturing systems will change. The smart factory introduces changes to the factors and elements of traditional manufacturing systems and incorporates the current requirements of smart systems so that it can compete in the future. An increasing amount of research in both academia and industry is dedicated to transitioning the concept of the smart factory from theory to practice. The purpose of the current research is to highlight the perspectives that shape the smart factory and to suggest approaches and technical support to enable the realization of those perspectives. This paper fills this gap by identifying and analyzing research on smart factories. We suggest a framework to analyze existing research and investigate the elements and features of smart factory systems

Manufacturability of Overhanging Holes Using Electron Beam Melting

This study aims to investigate the manufacturability of overhang round holes with and without support. The experiments were conducted by electron beam melting (EBM) using a Ti6Al4V powder. A large number of overhanging holes with and without support were fabricated and evaluated. The geometrical accuracy, mechanical properties, and microstructures were utilized as a measure of the process performance. It was demonstrated that overhanging features can be built successfully without support up to a certain dimension (or threshold value). Beyond that value, a minimal support structure can be employed to achieve the most suitable trade-off between production time, cost, and accuracy