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The study of the methods revealed their advantages and disadvantages for further synthesis and optimization. The main task was to improve the most suitable method, which will have the maximum number of affecting factors. The experimental method is highly accurate, but it requires high costs to work on analogues for each specific type of fasteners. The calculated method based on a single experiment allows to determine time standards for various fasteners. The given method does not require high costs for experiments, but like the experimental method, does not take into account performance degradation with continuous operation time. This leads to serious errors in obtaining time standards for a large number of fasteners. The article shows the optimized model of calculated method, based on a linear approximation of dependence of the number of fasteners replacements (removals/installations) on time at multiple intervals. The optimized model allows to obtain time standards of typical fasteners replacement with different geometric characteristic taking into account performance degradation over time. Several experiments on the aircraft were conducted for testing the improved calculated method. On the basis of the experimental data the researchers built graphs of the number of fasteners replacements (removal/installation) on time with different geometric characteristics taking into account performance degradation over time. The data obtained is advisable to use for calculation maintainability factors on aircraft design stages. Program realization of these methods and systematization of the received time standards allow to improve maintainability, due optimization number and position of airframe fasteners and systems units and aviation equipment for the aircraft being designed and modernized. Application of the automated systems of design and analysis will contribute to labor input decrease at the aircraft maintainability analysis.

The paper outlines the main problems and perspectives of methods development for regulation and finding compliance of aircraft during the type design maintainability certification. Mentioned requirements and methods relevance are related to the fact that aircraft continuing airworthiness at the operational stage is possible only with a reasonable combination of the maintenance documentation instructions for continuing airworthiness of a type design and the required level of its maintainability, which both meet the minimum requirements of airworthiness standards. Deficiencies in those requirements and means of compliance have notable influence on the safety and effectiveness of air transportation. Main ICAO standards and international practice of regulation and evaluation of aircraft maintainability and instructions for continuing airworthiness are briefly analyzed. On the base of aircraft maintenance requirements analysis recommendations proposed aimed to further develop regulations and means of compliance for a type design maintainability certification. For solving this problem there is a need to implement certain scientific and practical developments in the domain of integrated logistic support as a technology which integrates the reliability, maintainability and other technical operating capabilities activities for a newly-designed aircraft in order to create its effective maintenance system. The kinds of requirements within the aviation regulations and means of compliance for them are recommended, which have to be corrected and developed, as well as directions of works necessary for that, including implementation of computer modelling and prototypes testing for showing compliance of aircraft with the maintainability certification requirements. It is shown a need for implementation of the scientific and practical results of research in integrated logistic support domain which allow for interconnect of the reliability and maintainability activities within a new aircraft design in order to integrate systematically reliability requirements with the necessary maintenance action in support of reliability and with the required for those maintenance works level of type design maintainability.

The solution to the problem connected with increasing the service reliability of the combine harvesters at the expense of cutting time on the delivery of spare parts to the field is offered.

An effective operations of a projection spot welding (PSW) machine is closely related to the effec-tiveness of the maintenance. Timely maintenance can prevent failures and improve reliability and maintainability of the machine. Therefore, establishing the maintenance frequency for the welding machine is one of the most important tasks for plant engineers. In this regard, reliability analysis of the welding machine can be used to establish preventive maintenance intervals (PMI) and to identify the critical parts of the system. In this reliability and maintainability study, analysis of the PSW machine was carried out. The failure and repair data for analysis were obtained from automobile manufacturing company located in Uzbekistan. The machine was divided into three main sub-systems: electrical, pneumatic and hydraulic. Different distributions functions for all sub-systems was tested and their parameters tabulated. Based on estimated parameters of the analyzed distribu-tions, PMI for the PSW machines sub-systems at different reliability levels was calculated. Finally, preventive measures for enhancing the reliability of the PSW machine sub-systems are suggested.

Copyright of Journal of Education & Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Resilience is an intrinsic characteristic of systems. Through it, the capacity of a system to react to the existence of disruptive events is expressed. A series of metrics to represent systems' resilience have been proposed, however, only one indicator relates the availability of the system to this characteristic. With such a metric, it is possible to relate the topological aspects of a system and the resources available in order to be able to promptly respond to the loss of performance as a result of unexpected events. This work proposes the adaptation and application of such a resilience index to assess the influence of different maintenance strategies and topologies in fleets' resilience. In addition, an application study considering an actual mining fleet is provided. A set of critical assets was identified and represented using reliability block diagrams. Monte Carlo simulation experiments were conducted and the system availability data were extracted. Resilience indexes were obtained in order to carry out the definition of the best maintenance policies in critical equipment and the assessment of the impact of modifying system redundancies. The main results of this work lead to the overall conclusion that redundancy is an important system attribute in order to improve resiliency along time. [ABSTRACT FROM AUTHOR]

Introduction: Successive code changes during the maintenance phase may cause the emergence of bad smells and anti-patterns in code and gradually results in deterioration of the code and difficulties in its maintainability. Continuous Quality Control (QC) is essential in this phase to refactor the anti-patterns and bad smells. Objectives: The objective of this research has been to present a novel component called Code Deterioration Watch (CDW) to be integrated with existing Issue Tracking Systems (ITS) in order to assist the QC team in locating the software modules most vulnerable to deterioration swiftly. The important point regarding the CDW is the fact that its function has to be independent of the code level metrics rather it is totally based on issue level metrics measured from ITS repositories. Methods: An issue level metric that properly alerts us of bad-smell emergence was identified by mining software repositories. To measure that metric, a Stream Clustering algorithm called ReportChainer was proposed to spot Relatively Long Chains (RLC) of incoming issue reports as they tell the QC team that a concentrated point of successive changes has emerged in the software. Results: The contribution of this paper is partly creating a huge integrated code and issue repository of twelve medium and large size open-source software products from Apache and Eclipse. By mining this repository it was observed that there is a strong direct correlation (0.73 on average) between the number of issues of type "New Feature" reported on a software package and the number of bad-smells of types "design" and "error prone" emerged in that package. Besides a strong direct correlation (0.97 on average) was observed between the length of a chain and the magnitude of times it caused changes to a software package. Conclusion: The existence of direct correlation between the number of issues of type "New Feature" reported on a software package and (1) the number of bad-smells of types "design" and "error prone" and (2) the value of "CyclomaticComplexity" metric of the package, justifies the idea of Quality Control merely based on issue-level metrics. A stream clustering algorithm can be effectively applied to alert the emergence of a deteriorated module. [ABSTRACT FROM AUTHOR]

Methods for maintaining the technical condition and reliability control for tractors have been developed (faultlessness, durability, and maintainability) with respect to the main agricultural cycles by substantiating the lean approach to repair and maintenance actions during seasonal (winter) repairs, before agricultural work cycles, and directly during farm operations. The relationship between the technical condition of tractors and their reliability is established. [ABSTRACT FROM AUTHOR]

In this paper, the Reliability, Availability and Maintainability (RAM) analysis for the finite capacity Erlangian Phase-type Queueing model is studied with regard to failure and recovery rates. The arrival process of the machines to repair is assumed to follow Erlang distribution and the service process is exponentially distributed in FCFS discipline. Apart from the multi-phases in the queueing system two different environmental states such as the working and working- breakdown states were also taken into consideration. The transient state differential-difference equations for the general case and for the special case of N=5 is obtained. The results are presented numerically and graphically along with some special metrics such as MTBF and MTTR. The sensitivity analysis is also performed to find changes in different parametric values for the model. [ABSTRACT FROM AUTHOR]

Modern civilization cannot survive without software. Because software is the building block of new generation, the quality of software plays an important role in building new technologies and hence, low quality software is not acceptable. Any software is defined by its internal and external characteristics. To measure software quality, its internal attributes such as cohesion, coupling, etc. are used to assess the external quality attributes such as Reusability, Maintainability etc. Very few researchers has worked on assessing external attributes by measuring internal attributes for object oriented systems and all work has been done at class level by using class level metrics. Since classes are not suitable for large applications with higher level of organisation, packages were introduced. Organizing classes into package enhances the Reusability and Maintainability task for object oriented systems. Aspect oriented systems are designed to enhance object oriented systems by modularizing crosscutting concerns like logging, synchronization etc., which are scattered in multiple classes. In this paper, efforts have been made to assess external attributes—Reusability, Maintainability and Understandability, using internal attributes for Aspect oriented systems at package level using fuzzy logic. Software reusability and maintainability improves the quality of software product by reducing development/maintenance time, effort and cost. On the other hand, software Understandability directly or indirectly affects the quality of software. In this paper, fuzzy approach is proposed for assessing the three external attributes using package level internal attributes. Predictions made from the proposed fuzzy approach are validated by analyzing them with the values of external attributes measured for AJhotdraw, an AspectJ software. The results have shown that the predictions made through the proposed approach are correct. [ABSTRACT FROM AUTHOR]

The final architecture of a complex system reflect preferences of several value chain stakeholders on system attributes, also called "ilities". Owing to differences in their individual roles and responsibilities, different stakeholders prefer different approaches to architect and decompose a system to optimize their attributes of interest. However, owing to increasing complexity of modern engineering systems, optimizing multiple attributes of complex systems has become challenging; moreover, very few researches have been published in this regard. Thus, to address this gap in available literature, this paper presents a multi-attribute optimization framework for complex system decomposition. The proposed framework primarily optimizes two attributes—system robustness (to the perspective of the stakeholder), and modularity—while system maintainability is considered an optimization constraint. Feasibility of the proposed framework has been demonstrated through a case study, wherein system attributes of three different mechanical clock models having different architectures were optimized. [ABSTRACT FROM AUTHOR]

System downtime and unplanned outages massively affect plant productivity; therefore, the reliability, availability, maintainability, and safety (RAMS) disciplines, together with fault diagnosis and condition monitoring (CM), are mandatory in energy applications. This article focuses on the optimization of a maintenance plan for the yaw system used in an onshore wind turbine (WT). A complete reliability-centered maintenance (RCM) procedure is applied to the system to identify which maintenance action is the optimal solution in terms of cost, safety, and availability. The scope of the research is to propose a new customized decision-making diagram inside the RCM assessment to reduce the subjectivity of the procedure proposed in the standard and save the cost by optimizing maintenance decisions, making the projects more cost-efficient and cost-effective. This article concludes by proposing a new diagnostic method based on a data-driven CM system to efficiently monitor the health and detect damages in the WT by means of measurements of critical parameters of the tested system. This article highlights how a reliability analysis, during the early phase of the design, is a very helpful and powerful means to guide the maintenance decision and the data-driven CM. [ABSTRACT FROM AUTHOR]

Quality is an important goal desired by stakeholders in every Program Code (PC) developed to meet its functional requirements. However, empirical evidence on tools that measure code complexity and predict future maintenance before deployment is a problem. This work evaluates a Complexity Measurement Tool (CMT) and compares its performance with Code Metrics (CM), an equivalent existing complexity tool using Cyclomatic Complexity Value (CCV), Cyclomatic Complexity Category (CCC) and System's Computational Time (SCT). The CMT and Code Metric (CM) were subjected to evaluations by conducting two sets of controlled experiments involving each of 25 Student Programmers (SP) and Professional Programmers (PP). The quality of code artifacts obtained from the experiments was assessed using computed complexity values obtained with CMT and CM. Some other metrics obtained from the experiments were Effort/time range for Coding (EC) and Number of Bugs (NB). Data analysis was carried out using descriptive statistics and correlation, tested at α0.05. The mean CCV reported by CMT for SP and PP respectively, were 7.5±0.1 and 9.2±0.1, while for CM were 8.5±0.1 and 9.0±0.1 respectively. The CCC reported by CMT for both SP and PP were 'risk-free' and 'moderate-risk'. The average SCT obtained from CMT and CM for all the codes were 1.0±0.01 and 3.0±0.01 minutes respectively. A strong correlation exists between Line of Code (LoC) and CCV while a weak correlation between NB and CCV as measured by CMT for SP and PP. No CCC was reported by CM; also no CCV was computed by CM for codes with bugs. The included CCC makes CMT result interpretation better. The speed also gave it an upper hand over the code metrics embedded in Visual Studio environment. [ABSTRACT FROM AUTHOR]

Context: Architecture of a software system represents the key design decisions and therefore its quality plays an important role to keep the software maintainable. Code smells are indicators of quality issues in a software system and are classified based on their granularity, scope, and impact. Despite a plethora of existing work on smells, a detailed exploration of architecture smells, their characteristics, and their relationships with smells in other granularities is missing. Objective: The paper aims to study architecture smells characteristics, investigate correlation, collocation, and causation relationships between architecture and design smells. Method: We implement smell detection support for seven architecture smells. We mine 3 073 open-source repositories containing more than 118 million lines of C# code and empirically investigate the relationships between seven architecture and 19 design smells. Results: We find that smell density does not depend on repository size. Cumulatively, architecture smells are highly correlated with design smells. Our collocation analysis finds that the majority of design and architecture smell pairs do not exhibit collocation. Finally, our causality analysis reveals that design smells cause architecture smells. [ABSTRACT FROM AUTHOR]

With the increasing ability to generate actionable insight from data, the field of data science has seen significant growth. As more teams develop data science solutions, the analytical code they develop will need to be enhanced in the future, by an existing or a new team member. Thus, the importance of being able to easily maintain and enhance the code required for an analysis will increase. However, to date, there has been minimal research on the maintainability of an analysis done by a data science team. To help address this gap, data science maintainability was explored by (1) creating a data science maintainability model, (2) creating a new tool, called MIDST (Modular Interactive Data Science Tool), that aims to improve data science maintainability, and then (3) conducting a mixed method experiment to evaluate MIDST. The new tool aims to improve the ability of a team member to update and rerun an existing data science analysis by providing a visual data flow view of the analysis within an integrated code and computational environment. Via an analysis of the quantitative and qualitative survey results, the experiment found that MIDST does help improve the maintainability of an analysis. Thus, this research demonstrates the importance of enhanced tools to help improve the maintainability of data science projects. [ABSTRACT FROM AUTHOR]

Featured Application: Reliability, availability, and maintainability (RAM) analysis which could benefit all manufacturing plantssuch as food, automotive, oil, and gasetc., with immediate results to the quality of the products and to improve the design and operation of the production lines. The purpose of this paper is to provide findings for a thorough review of reliability, availability, and maintainability (RAM) analysis utilizing failure data from an ice cream industry. The case study shows how RAM analysis is very helpful in assessing maintenance intervals and in planning and organizing an effective maintenance strategy. RAM study was computed based on historical data gathered over a twelve-month period. Pareto analysis, descriptive statistics, trend, and serial correlation test of the data were conducted. The parameters for failure and repair data were computed for each machine and the complete ice cream manufacturing system. The RAM analysis assesses the current operations management and improves the quality, productivity, and performance of the line. It was found that: (a) preventive maintenance intervals for each machine and completed system for different reliability periods were calculated. (b) Two machines with the lowest reliabilities are the packaging machine and then on the freezer tunnel. The significance of these machines is vital and their maintenance must be thorough to avoid losses pertaining to quality and productivity, and (c) the worst maintainabilities occur at the exogenous machine, and on the ice cream machine, together with the complete production system. Moreover, as the RAM indices have been calculated to quantify and increase machines' performance, production managers and engineers can easily evaluate the next moves and decisions made with respect to the function of the system. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The reconfigurable vibrating screen (RVS) machine is an innovative beneficiation machine designed for screening different mineral particles of varying sizes and volumes required by the customers’ through the geometric transformation of its screen structure. The successful RVS machine upkeep requires its continuous, availability, reliability and maintainability. The RVS machine downtime, which could erupt from its breakdown and repair, must also be reduced to the barest minimum. This means, there is a need to design and develop a maintenance system model that could be used to effectively maintain the RVS machine when utilized in surface and underground mines. In view of this, this paper aims to develop a maintenance system model that could be used to effectively maintain the RVS machine when used in surface and underground mines. The maintenance system model unfolds the predictive (i.e. diagnosis and prognosis) algorithms, the e-maintenance strategic tools as well as the dynamic maintenance strategic algorithms required to effectively maintain the RVS machine. Four different case studies were presented in this paper to illustrate the applicability of this maintenance system model in maintaining and managing the RVS machine when utilized in the mining industries.

The objective of this paper is to describe an ergonomics contribution in maintainability. The economical designs, inputs and training helps to increase the maintainability indicators for industrial devices. This analysis can be helpful, among other cases, to compare systems, to achieve a better design regarding maintainability requirements, to improve this maintainability under specific industrial environment and to foresee maintainability problems due to eventual changes in a device operation conditions. With this purpose, this work first introduces the notion of ergonomics and human factors, maintainability and the implementation of assessment of human postures, including some important postures to perform maintenance activities. A simulation approach is used to identify the critical posture of the maintenance personnel and implements the defined postures with minimal loads on the personnel who use the equipment in a practical scenario. The simulation inputs are given to the designers to improve the workplace/equipment in order to high level of maintainability. Finally, the work concludes summarizing the more significant aspects and suggesting future research.

Despite allocating huge budgets to civil engineering projects, detailed planning, and employing human resources, project managers still face time, cost, and quality constraints. Most of these challenges are due to a lack of integration of different project phases and the limitations of the presence of construction and maintenance contractors in the initial stages of the project. Considering the benefits of applying constructability, operability, and maintainability (COM) concepts, many problems caused by lack of coordination, or duplications and weakness in management, and also time and extra costs due to lack of presence of construction and maintenance contractors in the early stages of the project are resolvable. In this regard, various studies have investigated the benefits of applying these concepts; however, there has been no comprehensive analysis of the benefits of COM. As a result of focus on the benefits of implementation of these concepts and evaluating the effect of each of these strategies and benefits, from different perspectives during various time periods, managers can increase project efficiency and productivity, and improve their performance, through using concepts and strategies of their implementation. This research aims to evaluate the trend of studies on the benefits of implementing constructability, operability, and maintainability in the construction industry. For that, the in-depth literature review method is applied. For qualitative analysis of the obtained information, descriptive analysis has been used. Then, the data was coded, and classified using Excel Software for quantitative data analysis. Finally, the charts presented were evaluated according to the classified fields of study. The necessity of performing such a study is significant because of the fact that a large share of a project’s problems, such as lack of plans’ integration and weakness of administrative system, and increasing time and cost, are due to lack of exchange of information and ineffective relationship between the design people and the construction and maintenance stakeholders, and ignoring the effects of design decisions on constructability and operability and maintainability implementation.

Construction managers in infrastructure projects in different societies offer and use approaches that can conclude each project’s triangle of cost, time, and quality in the most optimal mode, satisfying important needs of the projects. One of these approaches is benefiting from concepts of Constructability, Operability, and Maintainability (the threefold concepts of COM), which can satisfy such need in infrastructure projects. In order to implement each approach, while the desired approach is innovative, as well, there are some barriers. It is significantly required to offer solutions to obtain desired results from that approach. Therefore, the aim of this research is presenting solutions to overcome existing barriers in implementing the threefold concepts of COM in infrastructure projects. For that, the Meta-Synthesis method is applied, which is placed in qualitative research category. In order to analyze collected data, descriptive and pattern coding techniques have been used. As the result of this study, a systematic classification of the solutions to overcome barriers of implementing the threefold concepts of COM in infrastructure projects is presented. The aim of construction managers is successful delivery of projects, for that, it is suggested to use such approaches that result in integration of different project life cycle phases. This facilitates optimization of project time and cost, aiming to provide a better quality of constructions. Therefore, in order to achieve infrastructure projects main objectives, such approaches are to be used, and in order to overcome barriers in implementing them, some solutions are to be identified, classified and presented.

Maintainability plays a fundamental role for achieving success in software system and it is con-sidered as an important quality characteristics. Maintainability may be predicted efficiently by us-ing soft computing techniques as they provide good results. In this paper similarity- based ap-proach is used with the contribution of fuzzy Analytical Hierarchical Process (AHP) and fuzzy technique for order preference by similarity to ideal solution (TOPSIS) at 2-level hierarchy. Here similarity- based approach illustrates the combine approach of fuzzy AHP and fuzzy TOPSIS. This approach is used to provide the rank of software to select the best one for maintainability estimation. Also, several factors are presented that influence the software maintainability. These factors are taken as criterion and three software products are taken as alternatives.

Purpose. The paper should consider lowering the labour input of maintenance of drive gears operation of vehicles power plants at the expense of working out the coupling construction having low duration of substitution of elastic element and a justification of its force, power and strength parameters. Methodology. During development of coupling construction with increased maintainability the criterion of minimum average labour input of its reconstruction has been used. Constructive-power parametres of coupling were defined with the use of classical methods and statics and calculus theorems. Simulation of couplings operation is executed by numerical methods for couplings of concrete executions with the use of modern program complexes. Findings. Authors developed the coupling with rope elastic elements having low labour input of elastic element substitution due to multiple-purpose construction of tightening elements and pins with open slots in which the rope sequentially can be included is developed. The dependences are received, allowing to define power loads of elements of a coupling, and also to execute selection of ropes and calculation of strength of tightening elements. With obtained dependence the coupling with rope elastic elements for substitution of coupling Vulkan propulsion plant of the bulk ship of the project 2-95А/R is calculated and designed. The integrated definition of time for rope substitution in the offered coupling with application of specifications has displayed that for execution of this process it is necessary to expend about 150 minutes of time that is much less than 530 mines necessary for substitution of elastic membranes of base coupling Vulkan. Originality. The estimation of the basic constructive, power and strenght parametres of coupling with face installation of a rope with increased maintainability is executed. Practical value. Construction of a coupling with increased maintainability equipped with rope elastic elements is offered in the paper. Application of such coupling in power installations can reduce expenditures of time and resources to maintenance operation and to lower cost of transportations.