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The structure of steering gear’s HATLAPA mechanism is analyzed. It is shown that presence of redundant constraints in it increases laboriousness of gear montage and respectively worsen maintainability. On the basis of provided analysis developed mechanism with reduced more than twice redundant constrainsts number.

Setiap tahunnya, jumlah pengguna aplikasi seluler terus bertambah. Hal ini menyebabkan pengembang aplikasi seluler dituntut untuk mengembangkan produknya dengan cepat. Framework antarmuka pengguna lintas platform Flutter dan React Native menjadi sangat populer karena kemampuannya untuk dikompilasi ke berbagai jenis sistem operasi perangkat seluler. Namun, di antara kedua framework tersebut, belum diketahui manakah yang memiliki maintainability yang lebih baik. Tahap perawatan perangkat lunak merupakan tahap yang memakan paling banyak waktu, tenaga, dan usaha. Sehingga, penting untuk mengetahui framework mana yang basis kodenya lebih mudah dirawat. Pada penelitian ini, aplikasi media komunikasi untuk taman kanak-kanak dengan kompleksitas use-case yang beragam digunakan sebagai bahan untuk membandingkan maintainability Flutter dan React Native. Basis kode yang dikembangkan masing-masing diukur menggunakan A Code Quality Metrics Model for React-Based Web Applications. Hasil penelitian menunjukkan bahwa basis kode yang ditulis menggunakan Flutter memiliki maintainability lebih tinggi dibandingkan React Native. Faktor yang mempengaruhinya adalah bahasa pemrograman yang digunakannya, yaitu Dart untuk Flutter dan JavaScript untuk React Native, serta cara penulisan komponen yang berbeda antara Flutter dan React Native Mobile phone users are increasing every year. This demands mobile application developers to speed up their development time. Flutter and React Native, which are cross-platform user interface framework, become more popular due to their ability to compile to any mobile operating system. But, it is not yet known which of the two frameworks have the better maintainability. Maintenance is a step in software development process that consumes most of the development effort. So, it is important to know which framework produces the more maintainable code base. In this research, a communication media application for kindergarten with diverse use case complexity is used for comparing maintainability between Flutter and React Native. Each code base are measured using A Code Quality Metrics Model for React-Based Web Applications. The result is code base that are developed using Flutter has more maintainability than React Native. The influencing factors are programming languages used, which are Dart for Flutter and JavaScript for React, as well as how components in each frameworks are written.

Earth station system plays an important role to ensure that a satellite communication system runs efficiently. Redundancies of the subsystems and regular maintenance planning can improve the earth station system. Organising system affordability can be challenging as more redundancies would acquire more maintenance. Thus, a sustainable framework that considers an earth station system's reliability, cost, and maintainability was modelled. 2-parallel, 3-parallel, and 4-parallel earth station system configurations were studied with five mean time between failures (MTBF). The results showed that an earth station that was configured with 2-parallel configuration provided an optimum reliability system performance though both 3-parallel and 4-parallel configuration provided higher reliability. Moreover, the 2-parallel configuration was also cheaper in terms of operational cost if compared to the 3-parallel and the 4-parallel configurations. Hence, this sustainable framework comprising the reliability and operational cost elements were modelled based on the 2-parallel configuration with the proposed maintenance activities. Moreover, the computed root mean square (RMS) values for both new reliability and new operational cost models yielded smallest values of 20.84% and 22.82% respectively. Thus, these RMS values for both reliability and operational cost models based on 2-parallel configuration are suitable to be applied in the earth station system design. [ABSTRACT FROM AUTHOR]

Maintenance concerns most of the artifacts, referring simultaneously to the socio-cultural, technical and managerial spheres. Contemporary scenarios impose an overall rethinking, where key-topics such as tradition, consumerism, sustainability and digitization become pivotal in the search for suitable production models, between post-industrial and neo-craftsmanship, in order to have fresher references for the maintenance activities. In the construction field, maintenance is not limited to the objective of prolonging the duration of quality levels that only affect direct users, but also has important implications of a social and collective nature, in the case of both public and private buildings and spaces. Despite this and other specific features, the parallelism between building maintenance and manufacturing maintenance was fundamental in the last quarter of the 20th century, when the subject made its way into the technological culture of architecture, in search of references that could replace pre-industrial habits. In support of the theoretical rethinking of maintenance (an activity which, like the Sisyphean task, does never foresee a definitive completion), the article suggests some considerations referring in particular to the reinforced concrete: a structural material almost omnipresent in the built environment since the second half of the last century, which poses significant problems in terms of duration and not only. In conclusion, some possible developments are presented, distinguishing between newly constructed and existing reinforced concrete constructions. [ABSTRACT FROM AUTHOR]

Purpose: Reliability and maintainability are the key system effectiveness measures in process and manufacturing industries, and treatment plants, especially in E-waste management plants. The present work is proposed with a motto to develop a stochastic framework for the e-waste management plant to optimize its availability integrated with reliability, availability, maintainability, and dependability (RAMD) measures and Markovian analysis to estimate the steady-state availability of the E-waste management plant. In the analysis an effort is also made to identify the best performing algorithm for availability optimization of the e-waste plant. Methodology: A stochastic model for a particular plant is developed and its availability is optimized using various metaheuristic approaches like a genetic algorithm (GA), particle swarm optimization (PSO), and differential evolutions (DE). The most sensitive component is identified using RAMD methodology while the effect of deviation in various failure and repair rates are observed by the proposed model. The failure and repair rates follow an exponential distribution. All time-dependent random variables are statistically independent. Originality/Novelties: A novel stochastic model is presented for an e-waste management plant and optimum availability is obtained using metaheuristic approaches. The proposed methodology is not so far discussed in the reliability analysis of process industries. Findings: The numerical results of the proposed model compared to identify the most efficient algorithm. It is observed that genetic algorithm provides the maximum value (0.92330969) of availability at a population size 2500 after 500 iterations. PSO algorithm attained the maximum value (0.99996744) of availability just after 50 iterations and 100 population size. So, its rate of convergence is faster than GA. The optimum value of availability is 0.99997 using differential evolution after 500 iterations and population size of more than 1000. These findings are very beneficial for system designers. Practical Implications: The proposed methodology can be utilized to find the reliability measures of other process industries.

The equipment in underground mines provides a continuous production flow, depending on the way their quality is preserved during their operation. The TR-7A scraper conveyer subassemblies, which function in the Jiu Valley coal basin and are subjected to abrasion wear, showed a high failure frequency (chains, chain elevators, and driving and turning drums), as well as the hydraulic couplings and certain electric equipment of the same machinery. The data collected following the TR-7A scraper conveyer at work allowed the parameters to be determined that characterise the reliability and maintainability of the above-mentioned components, the failure modes, and their effects. Using calculation methods, the interpretation of the results has been facilitated, with a view to reducing maintenance costs and obtaining an 80% reliability for the components with the most failures, in the case of the TR-7A scraper conveyer. [ABSTRACT FROM AUTHOR]

The challenges of sustainability and maintainability to implement the industrial filtration technologies in the natural gas industry necessitate a systematic and practical assessment. With the target of balance between the issues in the context of sustainability and maintainability policies, criteria (principles) including economic, environmental, social, and maintainability aspects are taken into consideration. This work aims at developing a novel hybrid decision support system (DSS) namely q-rung orthorpair fuzzy set-based MAIRCA (Multi-Attributive Ideal-Real Comparative Analysis). The proposed DSS is applied to prioritize industrial filtration technologies considering the sustainability and maintainability principles. These technologies are considered for controlling contaminants produced by the natural gas industry in Iran. The prioritization of the considered technologies is obtained from the most to least preferred as: Cyclo-filter, Cyclone separator, Backwash, Gravity separator, and Basket strainer, respectively. The Cyclo-filter technology is selected as the preferable alternative. The adaptability of this technology with the regional and local states of the study area has assisted to make it the most suitable technology. The decision-making framework can help to give a new and practical insight for the policymaking in the field of process energy and environmental systems especially in the natural gas industry to control contamination. [Display omitted] • Industrial filtration technologies for the natural gas processing plant are prioritized. • A novel decision support system based on q-rung orthopair fuzzy set is introduced. • Sustainability and maintainability aspects are the criteria of the decision-making. [ABSTRACT FROM AUTHOR]

In software engineering, a software development process, also known as software development life cycle (SDLC), involves several distinct activities for developing, testing, maintaining, and evolving a software system. Within the stages of SDLC, software maintenance occupies most of the total cost of the software life. However, after extended maintenance activities, software quality always degrades due to increasing size and complexity. To solve this problem, software modularisation using clustering is an intuitive way to modularise and classify code into small pieces. , A multi‐pattern clustering (MPC) algorithm for software modularisation is proposed in this study. The proposed MPC algorithm can be divided into five different steps: (1) preprocessing, (2) file labelling, (3) collection of chain dependencies, (4) hierarchical agglomerative clustering, (5) modification of the clustering result. The performance of the proposed MPC algorithm to selected clustering techniques is compared by using three open‐source and one closed‐source software programs. Experimental results show that the modularisation quality of the proposed MPC algorithm is nearly 1.6 times better than that of the expert decomposition. Additionally, compared to other software clustering algorithms, the proposed MPC algorithm, on average, has a 13% enhancement in producing results similar to human thinking. Consequently, it can be seen that the proposed MPC algorithm is suitable for human comprehension while producing better module quality compared to other clustering algorithms. [ABSTRACT FROM AUTHOR]

The purpose of this article is to choose a maintenance procedure for the critical equipment of a forging production line with five machines. The research method is quantitative modelling and simulation. The main research technique includes retrieving time between failure and time to repair data and find the most likely distribution that has produced the data. The most likely failure rate function helps to define the maintenance strategy. The study includes two kinds of maintenance policies, reactive and anticipatory. Reactive policies include emergency and corrective procedures. Anticipatory policies include predictive and preventive ones combined with a total productive maintenance management approach. The most suitable combination for the first three machines is emergency and corrective choice. For the other machines, a combination of total productive maintenance and a predictive approach is optimal. The study encompasses the case of a serial production manufacturing line and maximum likelihood estimation. The failure rate function defines a combination of strategies for each machine. In addition, the study calculates the individual and systemic mean time to failure, mean time to repair, availability, and the most likely number of failures per production order, which follows a Poisson process. The main contribution of the article is a structured method to help define maintenance choices for critical equipment based on empirical data. [ABSTRACT FROM AUTHOR]

The ability to assess the risks of the functional safety of railway tracks allows harmonizing characteristics of track elements under certain operating conditions under certain maintenance for the efficient use of the track structure throughout its life cycle. The concept of detailing conditions of the interaction of the rolling stock and railway track was used for the productive solution of tasks of infrastructure functional safety assessment. The paper formed an approach to the analytical solution of determination problems of deformability parameters over time using the elastic waves theory. The formation method of interconnections between the technical and economic aspects of the operation of railway infrastructure was proposed. The criteria of deformability work and intensity of use were utilized for the effective use of the track structure through its life cycle. The results of calculations are presented to assess changes in the deformability behaviour of the track elements and structure when the force and speed parameters of the operating conditions change, as well as the algorithm of the method for estimating the operation deformability of the railway track. Thus, the proposed approach can be adapted to optimize objects by railway functional safety assessment at the stage of object operation simulation. [ABSTRACT FROM AUTHOR]

Software code is present on multiple levels within current Internet of Things (IoT) systems. The quality of this code impacts system reliability, safety, maintainability, and other quality aspects. In this paper, we provide a comprehensive overview of code quality-related metrics, specifically revised for the context of IoT systems. These metrics are divided into main code quality categories: Size, redundancy, complexity, coupling, unit test coverage and effectiveness, cohesion, code readability, security, and code heterogeneity. The metrics are then linked to selected general quality characteristics from the ISO/IEC 25010:2011 standard by their possible impact on the quality and reliability of an IoT system, the principal layer of the system, the code levels and the main phases of the project to which they are relevant. This analysis is followed by a discussion of code smells and their relation to the presented metrics. The overview presented in the paper is the result of a thorough analysis and discussion of the author’s team with the involvement of external subject-matter experts in which a defined decision algorithm was followed. The primary result of the paper is an overview of the metrics accompanied by applicability notes related to the quality characteristics, the system layer, the level of the code, and the phase of the IoT project.

This paper illustrates the impact of wind turbine (WT) subassemblies’ availability on WTs’ performance. Complete and detailed reliability, availability, and maintainability (RAM) analysis of various subassemblies of WTs utilizing the Weibull probability density function (PDF) is also introduced. A modified dynamic important measures-based reliability and availability are presented to show the significant impact of various WT subassemblies on the overall system performance. This method is mainly utilized to rank the WT subassemblies regarding their impact on the system reliability and availability, identifying the subassemblies that the planned maintenance should focus on. Dynamic ranking of WT subassemblies is obtained to achieve the desired level of reliability and availability. The obtained results demonstrate the effectiveness and efficiency of the proposed approach that achieves the system’s secure operation and improves system reliability and availability.

Obtaining system availability in an engineering design is trickish and challenging, especially when there is a reduction in capacity; however, it supports system maintainability. In this paper, a mathematical model for finding the availability under the reduced capacity has been proposed using the Chapman Kolmogorov approach with the help of transition diagrams associated with various possible combinations of probabilities. The paper observes the most critical subsystem by selecting variable failure and repair rates from different subsystems. It deals with the sensitivity analysis of a complex repairable threshing combined machine comprising subsystems in a series configuration and the threshing machine consisting of 21 subsystems. The device works in total capacity when the threshing drum and feeding Hooper work in the complete state, and the concave subsystem and blower work with reduced power. This study dealt with uncertain data and was analyzed analytically using a complex repairable system. The availability of the entire machine has been investigated analytically, and various availability indices such as subsystems extruder have been computed and reported. The study discovered that subsystem extruder has the most impact on some subsystems’ overall system availability.

The maintainability of sewer infrastructure systems is vital for public health, environmental protection, and the overall well-being of communities. However, maintenance and repair activities for sewer pipelines are often constrained, leading to challenges in effectively managing such infrastructures. To address these challenges, this study assessed the maintainability of sewer pipelines. A total of 15 defects were identified and categorized into structural, hydraulic, and quality defects after a comprehensive literature review was conducted and sewer pipeline experts were interviewed. Each failure caused by these defects was categorized as a pipe collapse associated with structural defects, sewer system overflow (SSO), odor, and groundwater contamination associated with quality defects. Apart from assessing the defects, the study identified potential solutions. After that, the obtained data were analyzed to determine the relative significance of each probability identified and its impact on four parameters, economic, social, environmental, and detection difficulty, using the relative importance index (RII), while the risk value index (RI) was applied to prioritize the defects. Furthermore, a data reliability assessment was utilized to evaluate internal consistency. The findings indicate that the probability of joint defects in the structural category caused by weaknesses in welded joints due to the misalignment of plastic pipes or joints, especially spigot and socket joints for rigid pipes, was the highest (RII = 0.733). Additionally, the ranking showed that the dumping of FOG had the highest priority, with an RI value of 0.535. This study offers a comprehensive maintainability framework that can be utilized by agencies assessing their current sewer infrastructure systems, in particular Arab Gulf countries including Saudi Arabia, which is the subject of this study.

Reachability, as a vital parameter in product maintainability design, exerts a tremendous influence in practical maintenance, especially in the usage stage. To decrease subjectivity in maintenance reachability analysis, this study proposes an automatic and quantitative approach based on the spatial data of the human arm to implement maintenance reachability analysis. The approach focused on two aspects, namely, accuracy and efficiency. In terms of accuracy, the presented methodology starts from the maintenance spot where the human hand is attached. An original global data sequence set was generated, including the wrist, elbow, and shoulder joints, under the constraints of kinematics, in which a data sequence represents an arm motion. Moreover, the surrounding objects are represented by their geometric data, in which each data sequence is analyzed to judge whether collision occurs between arm segments and surrounding objects. In this filtering process, the data sequence is retained if the aforementioned collision does not occur. In terms of efficiency, owing to the large number of global data sequences, the efficiency of the interval selection in collision calculation is also taken into consideration in this methodology. Unlike the traditional methods in the virtual environment, the starting point is the maintenance spot, rather than the human body. Hence, nearly all possibilities of arm postures are considered in a global perspective with little subjective involvement, which enhances the automation and objectivity in maintenance reachability analysis to a certain extent. The case study shows the usability and feasibility by a practical maintenance scene. [ABSTRACT FROM AUTHOR]

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Code smell causes side effects in the source code and impact the code quality. It is beneficial to recognize code smells to improve software quality. Despite 22 classical code smells as characterized by Martin Fowler, all classical code smells have not been considered for the identification and refactoring. Temporary field code smell is one such code smell that has not been given an appropriate level of attention so far regarding its detection as well as refactoring. In this paper, we have proposed a novel metric-based method and developed a tool to detect temporary field code smell. The proposed method works on three novel metrics in addition to existing metric TCC (tight class cohesion) and three new rules (R1, R2, and R3) to detect temporary field code smell. Detection rules were tested on ten open-source GitHub Java projects used in the literature. Results demonstrate that projects under the study that had non-cohesive classes have shown the presence of temporary field code smell ranging from 54% to 100%. Findings have additionally demonstrated that for the undertaken projects, there exists a strong positive correlation between the number of classes exhibiting temporary field smell and number of non-cohesive classes present in a project. [ABSTRACT FROM AUTHOR]

Surface mining is the world's most costly industry due to its enormous expenses. Reduced production is forcing mining companies to automate their equipment, predominantly heavy earth mining machinery (HEMMs), for example, dump trucks, shovels, and dozers. The backbone of pit mining is the crawler dozer, commonly known as a dozer. Crawler dozers are tracked earth-moving machines with metal blades positioned in front for pushing materials such as rocks, soil, etc. In order to survive the harsh competition, dozers must be durable and adequately maintained. Crawler dozers work under challenging conditions to avoid production delays that result in losses such as breakdowns, transmission failures, and other issues in mining operations. Transmission failures, among other issues with dozers, are one of the hardest to resolve. This study evaluates the reliability, availability, and maintainability (RAM) of a BD155 crawler dozer transmission using failure and repair data and the Markov method. A realistic case study on (BD155) transmission failure and associated subsystems has been performed. Potential approaches and alternatives are also identified to increase dependability and performance. This article also discusses best maintenance practices for minimizing transmission failures and boosting productivity. The availability of the BD155 increases to 71% from 62% using proper planning and maintenance. [ABSTRACT FROM AUTHOR]

Tunnelling is a vital geotechnical engineering feature of underground transportation systems that is potentially hazardous if not properly investigated, studied, planned, and executed. A reliability, availability, and maintainability (RAM) analysis is one of the main practical techniques in machinery-based projects to recognize the failure and repair rates of machines during or after their operations. RAM analysis of mechanized tunneling can help to manage the project safety and cost, and improve the availability and performance of the machine. There are several methods to obtain and predict the RAM of a system, including the Markov chain simulation and other statistical methods; however, the result of the analysis can be affected by the selected method. This paper presents the results of a critical investigation on the RAM of the Earth pressure balance machines (EPBMs) used in developing an urban metro project in Isfahan, Iran. The five kilometer length of the first line of the Isfahan metro project was excavated using EPBMs over four years. After overhauling the EPBMs and making some minor changes, excavation of the second line started, and to date, about 1.2 km has been excavated by the refurbished machines. In the present study, a RAM analysis has been applied to electrical, mechanical, and cutter head subsystems of the EPBMs in Lines 1 and 2 of the Isfahan metro project over an 18- and 7-month period of machine operation, respectively. The results show that the estimated availability, A(t), determined by the Markov method, is closer to reality but cannot be propagated to reliability R(t) and maintainability M(t) analysis. It was also revealed that by predicting the required maintenance and proper planning, the overall availability of the EPBM was improved from 45% in Line 1 to 61% in Line 2. The outcomes of this study can be used in the future planning of urban tunneling projects to estimate machine, staff, and logistic performance with the least possible error, and appropriately arrange the factors involved in the system. [ABSTRACT FROM AUTHOR]

This paper presents the modelling and simulation of a complex system applying the hierarchical coloured Petri nets method to represent the failure and repair processes, as well as obtaining statistical data indicating its performance. The simulation was performed on the model of a mechanical system characterized by the FAMAE SG 542-1 war rifle, commonly used in the Chilean Army, through the CPN Tools and Python software representing how components perform of operation of this weapon. This behaviour is recorded through both software, obtaining the simulation data so that it will be possible to predict the condition of a component and the system in the future to generate corresponding action plans. [ABSTRACT FROM AUTHOR]

The objective of this research was to investigate the performance of the Finger Joint Fu-King Furnimate machine, especially for the most critical component of this machine. Based on historical data of machine damage, the Finger Joint Fu-King Furnimate is the machine that has the highest-level frequency of damage. Reliability, Availability, Maintainability, and Safety (RAMS) methods are proposed to analyze the machine's historical data. The result shows that the reliability of machine performance at t = 160 hours is only 27.42%, but the availability of machines is quite high, which passed the standard of 95%. Meanwhile, the maintainability of the machine is relatively fast, which the repair time of its critical component is 8 hours. The low-reliability critical machine spare part affected the safety of the spare part which the Safety Integrity Level (SIL) in the lowest standard (level 1). In general, the novelty of this research is to combine the application of the RAM method as the basis for analyzing machine performance with a safety analysis of the selected critical machine subsystems.

In recent years, using of the resilience concept has been increased in order to evaluate the response of systems against the failures. Resilience depicts the system ability to return to its normal operational status after failure accruing. According to the literature survey, there are various studies, which have been done in the field of engineering and non-engineering systems, and there is no study about applying resilience concept in the field of mining industry. In this paper, at first, resilience concept has been introduced and then the resilience of the mining fleet of Sungun copper mine has been estimated. Systems performance indicators include reliability; maintainability and supportability have been used in order to resilience estimation. The results showed that the resilience of the entire system for one hour of its function is equal to 83.1% and this value decreases to 37.1% after 10 hours. This means if there is a failure in the system; it will have 83.1% and 37.1% probabilities to be resilience against the failure event after 1 hour and 10 hours of system function.

Maintainability is one of the design parameters (reliability, availability, maintainability, and safety (RAMS)) and maintenance is needed to keep the respective design in sustainable use. At the same time, the human is involved in the form of interface and interaction in an engineered product/system designed. Ergonomics is a multi-disciplinary science that considers human capabilities and limitations in a broader sense. The objective of this paper is to integrate ergonomics into the maintainability design process in order to facilitate maintenance operation in lesser; time, cost, easier operation as well as the well-being of human who is involved. In other words, good ergonomics lead to good economics and in a broader sense, sustainability. This investigation shows that designing comfortable workplaces and lesser workload for maintenance operators will be beneficial for the maintainability design process and also improve the meantime to repair MTTR. In order to evaluate the effect of designed work-place and workload on maintainers 3 D Static Strength Prediction Program (3D SSPP) that is commonly used as an ergonomics evaluation tool in scientific studies was applied.

The rapid development of big data technologies can improve the maintainability of machines and equipment in manufacturing systems, which could impact the selection of the optimal system architecture. In this paper, two typical architectures for large manufacturing systems - serial lines in parallel and reconfigurable manufacturing systems - are considered, and their productivities are compared. A decision locus is calculated that divides the configuration space into two areas; in each area, one of the architectures is the preferred one. It is also investigated how the locus is affected by different parameters, such as system size, buffer capacity and machine or gantry maintainability. The analysis provides valuable managerial insights for designing the architecture of large manufacturing systems. [ABSTRACT FROM AUTHOR]

Introduction/purpose: At the end of 2019, the Government of the Republic of Serbia adopted the Strategy for the Development of Artificial Intelligence in the Republic of Serbia for the 2020-2025 period. This was a motivation for the author of this paper to try to give an overview of the current artificial intelligence (AI) applications in the field of reliability and maintenance, as well as its future applications. Methods: The overview is done mainly using available literature, mostly from the Science Direct database, using abstracts generally, and in some cases whole papers. Results: The result of this research is an overview of the artificial intelligence applications in the field of reliability and maintenance in the past thirty years. It also showed that AI systems can also be unreliable and need maintenance. Conclusion: Artificial intelligence is and can be applied in reliability and maintenance. The research of available literature showed that AI is more applied in maintenance than in reliability. The progress in AI is inevitable, so it is important to understand its potentials for application in reliability and maintenance as well as its possible drawbacks.