Sharif Digital Repository

In order to survive in the competitive market, companies should increase the availability of plants. In order to increase the availability of a system, the occurrence of failures should be decreased. It is not possible to eliminate all of failures simultaneously. It means, it is not cost effective and logical to concentrate on elimination of all failures. In Addition, the cause of some failures might not be eliminated. So, the occurrence of those failures should be postponed to the later time as much as possible. Therefore, the critical failure modes should be identified to be concentrated for further analysis. Ultimately; the root causes of these failures should be explored and if it is... 

The present research aims to examine the influence of response format on the reliability and validity of grammaticality judgment tests, which will also reveal some facts about the superiority of each format. To this end, the grammaticality judgment (GJ) test developed by Gass (1994) was selected as the instrument of the study, which was manipulated in terms of the response format while the original items remained intact. Thus, in the first phase of the study, a multiple-choice GJ test (MCGJT) was constructed to be compared with the traditional form, i.e., the dichotomous type (DGJT). In an interval of a month, the two tests were administered to a group of 110 engineering-major BS students at... 

In this study a brief definition of the basic concepts of the reliability and censoring data is given as well as the literature review of the censored data and introduction to concept of robust. In order to find suitable distribution by considering censored data, the goodness of fit test, Chi-squared test, and Anderson-Darling approaches are used. Moreover to estimate Parameter of the reliability distribution, Maximum Likelihood estimation (MLE) is given. A case study in an automotive part manufacturing system is presented and the distributions of reliability parameters of several critical components (i.e. reliability, hazard rate, etc.) have been estimated. Considering all data, and... 

Traditional assumptions about assessment and learning have been challenged in higher education. Alternative types of assessment have been introduced to align to the students’ learning aims. Although, the growing body of literature of alternative types of assessment such as peer-assessment and self-assessment shed light on the advantages and benefits of embedding assessment in classroom activities, there is not absolute agreement on the consistency and accuracy of these types of assessment. To this aim, this study attempted to investigate the reliability and validity of self-assessment and peer-assessment of Iranian EFL learners’ written and oral production. The data was obtained from 32... 

Supply networks are often faced with disruptions that hampered the flow of goods, and have brought irreparable consequences. In this thesis, we evaluate the robustness of three echelon scale free supply chain networks consist of manufacturers, distributers and retailers from the perspective of complex network topologies and investigate the effect of assortativity and disassortativity level on the robustness of scale free supply networks. For this purpose, we use the degree preserving rewiring approach in order to increase and decrease assortativity and disassortativity of scale free networks. Then we use metrics in order to investigate the robustness and flexibility of supply networks and... 

The research, Reliability Investigation for Increasing Safety in Iranian Railway Systems via TPM, aims to evaluate maintenance in Iranian Railway Systems, and its corresponding factors in impacting safety. As the title indicates, this study focuses on safety in Iranian railway systems, and thus provides a history of the rail industry, as well as its history in Iran. Additionally, four maintenance types: regular, preventative, corrective and critical are evaluated. This evaluation is done for each maintenance type based on a series of factors rated based on a questionnaire distributed amongst experts. 37 experts were surveyed consisting of rail industry employees, as well as university... 

The Internet is often used for communication-based applications such as online banking, stock trading, and shopping where service interruption is unacceptable. Thus, analysis of the impact of the failures of hardware, software, and related services’ performance quality of the service provided to users is of importance to designers and managers in these functions. In this study, we developed a strategy to the design of a dynamic combination of file servers with the aim of providing reliability and SLA. At first, we examine the reasons for the violation of service level in file host services and datacenters, and then we introduce the criteria to measure the violation of service level on the... 

Nowadays, in a highly competitive and rapidly growing manufacturing environment, firms and their manufacturing processes are compelled to be agile, dynamic, and productive. On the other hand, in the last century, the continuous growth of IT has led to emergence of innovative and essential technologies such as the Internet, cloud computing, and the Internet of Things. The integration of mentioned technologies in manufacturing has turned its structure from product-oriented to service-oriented. Also, the personalized services and resources, with limited capacity, have made the manufacturing processes more complicated. As a new generation of manufacturing systems, cloud manufacturing has... 

Cloud Manufacturing (CMfg) is a service-oriented manufacturing (SOM) paradigm that provides a dynamic, scalable, and virtualized working ecosystem. The CMfg collaborative structure can be modeled as a hyper-network-based service-demand matching architecture. It is enriched with quality of service (QoS) characteristics to produce customized products in a stable and reliable network. This stability should be considered in the overall manufacturing network mechanism. This Thesis has developed a multi-dimentional model and improved it by providing absorptive and adaptive strategies utilizing available resources and capacities to enhance the system’s stability and reliability against the...