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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. 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. 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. 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. The proposed methodology can be utilized to find the reliability measures of other process industries. [ABSTRACT FROM AUTHOR]

Dependency injection (DI) is generally known to improve maintainability by keeping application classes separate from the library. Particularly within the Java environment, there are many applications using the principles of DI with the aim to improve maintainability. There exists some work that provides an inference on the impact of DI on maintainability, but no conclusive evidence is provided. The fact that there are no publicly available tools for quantifying DI makes such evidence more difficult to be produced. In this paper, we propose two novel metrics, dependency injection-weighted afferent couplings (DCE) and dependency injection-weighted coupling between objects (DCBO), to measure the proportion of DI in a project based on weighted couplings. We describe how DCBO can serve as a more meaningful metric in assessing maintainability when DI is also considered. The metric is implemented in the CKJM-Analyzer, an extension of the CKJM tool to perform static analysis on DI detection. We discuss the algorithmic approach behind the static analysis and prove the soundness of the tool using a set of open-source Java projects. [ABSTRACT FROM AUTHOR]

Cognitive radio networks (CRNs) can facilitate ultra-reliable communication among IoT devices in the 6G environment by enhancing channel availability (CA) for primary and secondary users. However, CA does not necessarily lead to successful connection establishment unless receiver’s accessibility (RA) is guaranteed. This motivates us to propose the notion of connection availability (CoA) that incorporates RA into CA. We also introduce the idea of service maintainability (SM) that includes the effect of RA in service retainability. Additionally, spectrum utilization efficiency (SUE) is expressed and analyzed with and without considering the impact of RA. For performance evaluation, a channel reservation algorithm with customizable configurations is proposed. Furthermore, an analytical model is used to investigate the network performance for all key performance indicators (KPIs) under multiple channel failures and PU arrival rates and determine valuable tradeoffs among KPIs. [ABSTRACT FROM AUTHOR]

The two main research goals of this study are to develop a relationship diagram between the parameters of reliability and maintainability and to investigate the impact of reliability and maintenance on engineering design costs. In this study, we use the theory of reliability and maintainability parameters to derive the relationship between the parameters using block diagrams. Compared with onshore wind farms, offshore wind farms have higher reliability requirements, but the maintenance degree of offshore wind farms is lower due to environmental factors. This study proposes an important concept of reliability and maintenance for value engineering, which can help system design engineers and project engineers integrate reliability concerns in the design phase and operation and maintenance phase. [ABSTRACT FROM AUTHOR]

Model-Based Systems Engineering (MBSE) methods have developed a strong foothold in the design space in industry. These methods have proven fruitful when the right method is applied to the right problem. Reliability, Availability, and Maintainability (RAM) is an equally important area. Currently, there is a gap in applying a methodology to integrate the two in the design process, particularly when the design is complex. This work attempts to provide a methodology that results in the successful integration of RAM and MBSE that can be used during the early phases of design. The methodology was developed after an extensive literature review, followed by the illustration of the methodology through an example of a steam turbine fuel system. Each step of the method is applied and explained in the illustrative example, to include figures, tables, and calculations demonstrating the effectiveness of the method, concluding with evidence for validation. [ABSTRACT FROM AUTHOR]

Motors are one of the vital equipment and generally the higher in numbers in oil and gas processing facilities. The primary function is to drive the process equipment such as compressors, fans, pumps etc. Unreliability of the motors is a threat to safety but also to production loss and high operating expenditure. Motors experience higher failure rates and maintenance costs with age due to lower focus during useful life periods. In order to properly address the long-term reliability and maintainability of the motors and associated subsystems, this paper aims to propose a structured methodology and set of tools to ensure effective assessment. The proposed model mainly consists of data collection, analysis, assessment, financial analysis and later developed actions to properly address the concerns. Equipment failure and repair data is a challenge to any reliability assessment; hence, proposed methodology was introduced to collect, verify and validate the data. Later, multiple tools such as Pareto Analysis, Failure Mode and Effect Analysis and Root Cause Analysis were used to perform a detailed assessment. Weibull analysis was also explored to understand the failure modes, which ultimately helped in improving the availability of the motors. The proposed methodology has been applied to high-voltage motors to observe the effectiveness of the tools and proposed model in addressing reliability and maintainability. The results show significant reliability improvements of 12% (from 58% to 70%) and prove that the structured method can be effectively used in complex process facilities with significant benefits. [ABSTRACT FROM AUTHOR]

For any industrial entity put into operation, it is of interest to its ability to fulfil its mission under certain conditions, at a given time or during a given period of time, assuming that the means of maintenance are provided. This represents availability and is a complex form of system / product quality, as it includes both reliability and maintainability. Availability can be increased by: maximum reliability, maintenance, respectively by maximum maintainability, correct use of equipment / machines, renewal, optimization of reliability and maintainability characteristics, but provided that such balancing does not lead to contradictory solutions. The availability of a product will be higher the more reliable it is and requires less maintenance. It should be borne in mind that in order to ensure a certain level of reliability, maintenance costs must not exceed 10...20% of the purchase price of the product each year [1]. Restoration of reliability to a normal level is achieved through corrective or preventive maintenance. In practice, a compromise is sought between the purchase price, the service imposed and the accepted risk, as in order to achieve availability through reliability, very reliable parts must be used, which cost 5-10 times more than usual [2]. Maintenance-based availability results from the consideration that reliability is a probability of trouble-free operation over a period of time. Reliability is technically and financially limited. Defects in the initial period of operation of the product, as well as those in the final period derive from inevitable physical phenomena, and defects in the maturity period have a normal accidental character. In addition, the reliability can deteriorate over time even during storage, thus causing additional damage. Reliability is restored to its normal level through corrective or preventive maintenance, as failures are foreseeable or unpredictable. Product availability is the result of a combination of reliability and maintainability and they support each other. Increasing the maintainability of products leads to increased availability. In this case, the real maintainability of a burning oven of a cement factory was studied, with the aim of finding practical solutions to increase the service life. Achieving the proposed objective required monitoring the operation / failure of such equipment for nine months and statistical processing of the information obtained.

Indonesia has the potential for large solar power plants. It has relatively constant solar radiation because it is close to the equator. Besides, solar energy includes renewable energy that is more environmentally friendly and easier to apply in office areas, especially Wonogiri. However, it turns out that the solar power plant projects that have been built are not yet fully functional, and some have even failed. A lack of responsibility and maintenance causes this carried out after the project is complete. For this reason, it is necessary to estimate the reliability of these components and determine the maintenance schedule before the project is carried out. So that later they have a picture and be better prepared when this project is already underway. The fault tree method's failure factors are expected to create a picture to maintain reliability and determine the prioritized components for maintainability. For the results obtained to be more appropriate, apart from seeing the quantitative analysis output, the fault tree also needs to be adjusted to the component manual or datasheet to determine the replacement of spare parts and their maintenance. So that the resulting schedule for maintenance and replacement of spare parts. Thus, the solar power plant project that has been built will be more reliable and can be appropriately utilized.

Software architecture is known to be an effective tool with regards to improving software quality attributes. Many quality attributes such as maintainability are architecture dependent, and as such, using an appropriate architecture is essential in providing a sound foundation for the development of highly maintainable software systems. An effective way to produce a well-built architecture is to utilize standard architectural patterns. Although the use of a particular architectural pattern cannot have a preserving effect on software maintainability, the mere conformance of a system to any architecture cannot guarantee the system’s high maintainability. The use of an inappropriate architecture can seriously undermine software maintainability at lower levels. In this article, the effect of standard architectural patterns on software maintainability quality attributes is investigated. We develop a quality model for maintainability quality attributes, which is later used to compare various standard architectural patterns. We finish by investigating two real-world experiences regarding the application of a particular pattern to two different existing architectures, exploring the effect of the change in architecture on maintainability quality attributes.

This work deals with the Performance Modelling and purposed the Decision Support System (DSS) for maintenance priorities of an assembly line system using a probabilistic approach. This system consists of four subsystems i.e. Shot Peening, Painting Machine, Assembly Platform and Riveting Machine. Performance modelling among various subsystems has been done by Markovian approach. Steady state probabilities are determined by drawing transition diagram and solving the differential equations. Decision matrices are formed with the help of different combinations of failure and repair rates of all the subsystems. The key finding of this work is that painting machine is the most critical subsystem. [ABSTRACT FROM AUTHOR]

Climate change and growing energy demands have put maintainability in the limelight for the long-term performance of green building envelopes, especially for warm-humid regions with intense weathering. This study proposed a framework for predicting the maintainability performance of such envelopes in the Indian context. The country is a key player in the global energy sector because green certification is mandatory for large commercial projects. Design-related envelope defects with their precise causes and effects were collated from the literature, field study, and a questionnaire survey to determine their criticalities. The defects of green and conventional buildings portray similar profiles due to common weathering agents. Furthermore, for the envelope components under the broad groupings of wall, fenestration, and roof, a maintainability attribute checklist was developed from the existing standards and guidelines. Common design alternatives for each component were weighted according to their ability to mitigate both critical and noncritical defects. The maintainability performance of a suitably chosen demo building was predicted. Despite its high energy efficiency class and careful maintenance, defects were prevalent, indicating average maintainability. This explains why landmark green projects also deviate from their energy-saving targets. The accuracy of the proposed framework was found to be satisfactory by tallying predicted and actual defects. The work can contribute to the achievement of long-term envelope performance and resource saving. [ABSTRACT FROM AUTHOR]

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New systems are produced and developed to meet specific needs, and their reliability is the most important issue. In the maritime industry, evaluating failures in a ship’s propulsion system results in high costs and the loss of prestige for the company. Land/sea fleet employees need to detect and minimize the failures that may occur in ship propulsion systems in advance to ensure the continuity of the ships’ operations. In this study, the recorded failure data of four different ships belonging to a fleet in the last 10 years are used. Failures were examined as a whole since the ships have similar propulsion systems. The obtained failure data were grouped, and the average time to fix the failures was determined by the chief engineer and made suitable for reliability, availability, and maintainability (RAM) analysis. A suitable model was created for grouped failures by Isograph’s RWB software. As a result of the analysis of the propulsion system and its subsystems, the main engine of the ship was shown to have the best reliability. Furthermore, the most important components were the cylinders of the main engine as subsystems. This study highlights the components that are important to the reliability of a propulsion system. Thanks to the RAM analysis, improvements can be pinpointed on a ship’s propulsion system, which will increase the operations of the maritime industry. Reducing failures will further increase the confidence in maritime transport and strengthen its place among the modes of transportation. This study provides a valuable resource for academicians, experts, as well as companies working on reliability, availability, and maintainability in the future. [ABSTRACT FROM AUTHOR]

Recently, to evaluate the response of systems against disruptive events, the application of the resilience concept has been increased. Resilience depicts the system's ability to return to its normal operational status after the disruption. Various studies in engineering and non-engineering systems have only considered systems' performance indicators to estimate resilience. Therefore, the impact of operating and environmental factors (risk factors) has been neglected. In this paper, the influence of the risk factors (rock type), as well as the system's performance indicators, are considered in the resilience estimation of the excavator system of the Gol-E-Gohar Iron mine. [ABSTRACT FROM AUTHOR]

The maintainability of the software is one of the most substantial aspects when assessing software product quality. It is known as the easiness with which the current software can be changed. In the literature, a great number of models have been suggested to predict and measure maintainability during various stages of the Software Development Life Cycle, to conduct a comparative study of the existing suggested models of the prediction, only few attempts have been done. This study hints at the basics about the manner of how to measure maintainability in the object-oriented (OO) design knowing that the maintainability will be measured differently at every level. Also, we will concentrate on the artificial intelligence technologies of these studies.

Many resilience definitions and metrics have been presented across various disciplines in recent times. However, from a design and operations perspective, a limited effort is focused on quantifying the resilience of oil and gas support structures. This study proposes a methodology for structural resilience quantification of an offshore hydrocarbon pipeline. Resilience is modelled as a function of the structure’s time-dependent reliability, adaptability, and maintainability. The proposed model is demonstrated on an internally corroded offshore natural gas pipeline segment with multiple initial defects; and considers disruptive events arising from the leak, burst, and rupture failure modes. The resilience index and sensitivity analysis are evaluated for the offshore pipeline. The pipeline sensitivity analysis indicates the apparent effect of pipe wall thickness and defect depth growth rate on resilience over its design life. The outcome of this study provides an insight into the resilience quantification of structural systems considering multiple disruptive events. The proposed model is expected to serve as an essential tool for resilience evaluation during the design and operations of oil and gas structures.

Aviation maintenance needs to be continuously improved for many reasons: flight safety, the health of maintenance operators, and saving time and costs among other reasons. To preventively improve the working conditions, the Maintainability Department—the department designing the maintenance activity in the Technical Design Office—develops and uses simulation tools such as Virtual‐Reality (VR). To improve maintenance, maintainability stakeholders must perform Human Factors analysis through simulation tools. However, the use of VR requires specific knowledge and skills that should be learned by students in the university. The aim of this paper is to study the use of VR as a Teaching & Training tool as well as an Industrial tool in real on‐the‐job cases. Over 2 years (between 2018 and 2020), we have trained and observed 112 students. Two main surveys have been used, the first one at the beginning of the academic year (to better know students' previous experience in VR) and the second survey at the end of the year (to get students' feedback regarding their training year with VR). We have formulated and presented recommendations to apply better inductive‐deductive teaching approaches offering more cases studies and a better understanding of aviation maintenance by students. We have also made recommendations to improve the use of VR, for example, to reduce the discrepancies and inaccuracies between the virtual and real worlds. [ABSTRACT FROM AUTHOR]

The existing maintainable spacecraft costs a lot to realize the maintainability, and the technical development path is not clear, so it is difficult to popularize and apply. Based on the analysis of the technical characteristics of foreign maintainable spacecraft, this paper puts forward a general design method for maintainable spacecraft from three aspects: maintainable architecture, replaceable functional module architecture and plug-and-play interface architecture. Combined with the proposed method, a modular maintainable satellite with variable main structure configuration is designed, and the key technologies involved are described. The designed serviceable satellite takes the open mechanical system with variable configuration, distributed heterogeneous network system and refillable propulsion system as the core architecture, and the two-level functional modules and three-level interfaces as the repairable carrier. It realizes the maintainability at low cost, reduces the capability requirements for maintenance operators, and the system function and performance can evolve dynamically with the technology development. The proposed method and typical design case could provide reference for the development of maintainable spacecraft and corresponding technologies in China. [ABSTRACT FROM AUTHOR]

Today, with the advancement of technology and the use of advanced systems in the field of mining, one of the issues that can seriously affect the economic and operational conditions of a mine is the occurrence of system breakdowns. Given the importance of the loading system in mines and the high cost of downtime due to failure, one of the proposed approaches to deal with this issue is to use the concept of resilience analysis. Applying the notion of resilience to the field of mine engineering has a significant benefit for the safety and improves system performance after failure. Accordingly, in this paper, the resilience of the loading system of Jajarm bauxite mine in a period of 2 years is evaluated. By using statistical analysis, a suitable function is fitted to the TBF (time between failures) and TTR (time to recovery) subsystems, the reliability and maintainability values of the system are calculated, finally, using impact indicators such as supportability, organizational resilience, and PHM technology; total resilience of the loading system is calculated. The results show that the loading system resilience is at its highest level when PHM technology and organizational resilience are at 95% so that the loading system resilience is 92% after 100 h of operation. This means that the loading system is 92% more likely to recover after a breakdown and returns to pre-breakdown conditions. [ABSTRACT FROM AUTHOR]