21 research outputs found

    Affective Factors on Reliability of Laboratory Tests Based on ISO 17025:2005

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    تعد معولية الفحوصات المختبرية الركيزة الأساسية في الجانب التطبيقي لجودة المشاريع إلانشائية، إذ لا يمكن قبول أو رفض المواد إلانشائية المستخدمة في تلك المشاريع إلاٌ بعد مرورها بالفحص المختبري الذي يتم بموجبه القبول أو الرفض لتلك المواد. أن العديد من المنظمات أخذت بالسعي نحو تحقيق الميزة التنافسية، وذلك بتقديم خدماتها بجودة عالية من خلال تطبيقها معايير إدارة الجودة الشاملة، فكان من الضروري للمختبرات إلانشائية تبني أدارة الجودة اسلوبا في عملها، لاسيما تطبيق معايير المواصفة العالمية ISO 17025:2005 مما يحسن أداء هذه المختبرات من الناحية الإدارية والفنية. يتضمن هذا البحث دراسة إحصائية لعينة من المختبرات إلانشائية وشركات المقاولات إلانشائية ودوائر تنفيذ المشاريع في بعض المؤسسات الحكومية، لتحديد العوامل المؤثرة على معولية (موثوقية) الفحوصات المختبرية، واثبتت النتائج لكل محور هي (مؤثرة، مؤثرة جدا) بحسب ما تم وضع ارقام إليها إذ ستقدم المنهجية المتبعة في البحث توصيات ومقترحات تساعد الكوادر العاملة في المختبرات بالتركيز على العوامل المؤثرة على معولية الفحوصات والتعامل معها على وفق معايير المواصفة العالمية ISO 17025:2005.The reliability of the laboratory tests is the main pillar in the applied side of the quality of the construction projects. The construction materials used in these projects cannot be accepted or rejected until they have passed the laboratory examination according to which these materials are accepted or rejected.. Many organizations have sought to achieve the competitive advantage by providing high quality services through the implementation of the overall quality management standards. It was necessary for the construction laboratories to adopt the quality management method in their work, in particular the application of the standards of ISO 17025: 2005, Which improve the performance of these laboratories in terms of administrative and technical. This research includes a statistical study of a sample of construction laboratories, construction contracting companies and project implementation entities in some government departments to determine the factors affecting the reliability of the laboratory tests. The methodology used in the research will provide recommendations and suggestions to help the laboratory staff focus on the factors influencing the Reliability of tests and handling them according to the  ISO 17025: 2005

    Fuzzy-Bayesian-network-based Safety Risk Analysis in Railway Passenger Transport

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    This study presents a fuzzy Bayesian network (FBN) method to analyze the influence on the safety risk of railway passenger transport applying different risk control strategies. Based on the fuzzy probability of the basic event determined by the expert group decision method, the proposed FBN method can reasonably predict the probability of railway passenger safety risk. It is also proven that control the risk in the safety management of railway passenger transport will be the most effective way to reduce the risk probability of the railway passenger transport safety

    Statistical Reliability with Applications

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    This chapter reviews fundamental ideas in reliability theory and inference. The first part of the chapter accounts for lifetime distributions that are used in engineering reliability analyis, including general properties of reliability distributions that pertain to lifetime for manufactured products. Certain distributions are formulated on the basis of simple physical properties, and other are more or less empirical. The first part of the chapter ends with a description of graphical and analytical methods to find appropriate lifetime distributions for a set of failure data. The second part of the chapter describes statistical methods for analyzing reliability data, including maximum likelihood estimation and likelihood ratio testing. Degradation data are more prevalent in experiments in which failure is rare and test time is limited. Special regression techniques for degradation data can be used to draw inference on the underlying lifetime distribution, even if failures are rarely observed. The last part of the chapter discusses reliability for systems. Along with the components that comprise the system, reliability analysis must take account of the system configuration and (stochastic) component dependencies. System reliability is illustrated with an analysis of logistics systems (e.g., moving goods in a system of product sources and retail outlets). Robust reliability design can be used to construct a supply chain that runs with maximum efficiency or minimum cost

    RFID benefits: looking beyond ROI

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    MBA Professional ReportWe explore whether benefits are being realized in RFID initiatives that are not being captured by traditional Return on Investment analysis. Utilizing the Naval Supply System Report, which found RFID technology does not create a positive ROI, we surveyed the participants to find benefits they received that were not addressed. 100% of the participants reported increased customer knowledge and increased timeliness of information. While this finding may not be enough to support the implementation of new technologies, it at least supports the idea that the new technologies do have real benefits. This report is therefore intended as a tool to be used by the Navy in addressing the idea that traditional ROI does not capture these intangible benefits. We acknowledge the fact that further study of this important issue is needed.http://archive.org/details/rfidbenefitslook109459979US Navy (USN) authors.Approved for public release; distribution is unlimited

    FAULT TREE ANALYSIS AS A MODERN TECHNIQUE FOR INVESTIGATING CAUSES OF SOME CONSTRUCTION PROJECT PROBLEMS

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    Construction projects contain many problems that can occur during the execution. Each problem results from many causes. Fault tree analysis (FTA) technique is a graphical model for analyzing causes of a problem (or undesired event) using logic gates to describe combinations of individual faults that can create an undesired event. Each level of the tree lists the lower level events that are necessary to cause the event shown in the level above it. The assessment process of a problem with FTA technique can be divided into two types: qualitative and quantitative assessment. As a case study to apply FTA technique in construction field, the researcher studied a building in Baghdad that had punching shear problem to analyze the causes lead to this problem. This research aims to introduce the main principles of FTA technique and how to use in identifying and analyzing the causes of problems that can occur in the construction projects. Also, it aims to compute the probability of occurrence of any problem or undesired event

    An iterative methodology for reliability prediction

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    While much research has focused on the development of reliability prediction methodologies for the electronics industry, far less work addresses the evaluation of mechanical rotating equipment. Structured prediction methodologies that consider and attempt to reduce the resource requirements of reliability prediction do not exist in this realm. Various prediction techniques to ascertain the failure rates of mechanical equipment are widely accepted and applied, each having different resource requirements and each inducing different degrees of uncertainty. A methodology is reported herein to assist the engineer in performing reliability prediction. This iterative framework utilizes simulation to evaluate the uncertainty of reliability prediction, and, in each iteration, identifies the critical components that have the greatest impact on the uncertainty of predicted reliability for the entire system. Non-critical components are not included in the more rigorous, and costly, �ubsequent iterations. Thus, the engineer is presented with a tool by which the resources consumed in reliability prediction may be reduced

    Risk of employing an evolvable production system

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    Nowadays manufacturing companies are facing a more challenging environment due to the unpredictability of the markets in order to survive. Enterprises need to keep innovating and deliver products with new internal or external characteristics. There are strategies and solutions, to different organisational level from strategic to operational, when technology is growing faster in operational level, more specifically in manufacturing system. This means that companies have to deal with the changes of the emergent manufacturing systems while it can be expensive and not easy to be implement. An agile manufacturing system can help to cope with the markets changeability. Evolvable Production Systems (EPS) is an emergent paradigm which aims to bring new solutions to deal with changeability. The proposed paradigm is characterised by modularity and intends to introduce high flexibility and dynamism at shop floor level through the use of the evolution of new computational devices and technology. This new approach brings to enterprises the ability to plug and unplug new devices and allowing fast reformulation of the production line without reprogramming. There is no doubt about the advantages and benefits of this emerging technology but the feasibility and applicability is still under questioned. Most researches in this area are focused on technical side, explaining the advantages of those systems while there are no sufficient works discussing the implementation risks from different perspective, including business owner. The main objective of this work is to propose a methodology and model to identify, classify and measure potential risk associated with an implementation of this emergent paradigm. To quantify the proposed comprehensive risk model, an Intelligent Decision system is developed employing Fuzzy Inference System to deal with the knowledge of experts, as there are no historical data and sufficient research on this area. The result can be the vulnerability assessment of implementing EPS technology in manufacturing companies when the focus is more on SMEs. The present dissertation used the experts’ knowledge and experiences, who were involved in FP7 project IDEAS, which is one of the leading projects in this area

    Fall risk assessment of bridge construction using Bayesian network transferring from fault tree analysis

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    Falling is the most common one during bridge construction. Current safety management on site mainly relies on checklist assessment. Yet the assessment result is often influenced by the ability and experience of the evaluator, thus is not impossible to achieve consistent and systematic assessment objective. Moreover, most critical factors that can prevent occurrence of accidents cannot be found from existing safety management and assessment method. This paper built a Bayesian Network (BN) model by converting Fault Tree to assess the fall risk of bridge construction projects. We analyse falling factors and their relationships in Bayesian Network, and collect prior probability event and calculate the probability for the entire model. Using the model to analyse and validate with the current bridge projects under construc­tion, the results from Bayesian Network is consistent with that from conventional labour safety performance assessment. Therefore, the ability to manage site safety of the model is proven to be useful

    CONSTRUCTION RISK MANAGEMENT

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    In most of the construction projects, there are many events or risks may occur during the execution of project. These risks (e.g. the excess of project cost or the expected time, increasing the prices of material and labor, accidents, changes, engineering errors or omissions, bad quality, delay in reaching the facilities to the site, etc.) may effect negatively on the project and the parties. Therefore, these risks must be identified and assessed accurately to avoid or reduce the negative effects for these risks. The concept of risk is used to assess and evaluate uncertainties associated with an event or a process. A construction process includes many uncertainties, therefore, the construction project’s parties are becoming aware of the construction process and thus the risks within this process are seeking more and more clarification that all is being done to remove foreseeable risk and minimize unforeseeable risk. It is also becoming clear that generic approaches to the management of risk are maturing and becoming easier to apply
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