Search results for "Reliability engineering"
showing 10 items of 224 documents
Modeling the energy and environmental life cycle of buildings: A co-simulation approach
2017
Abstract Building simulation is currently looking towards interdisciplinary experiences, aiming to the integration of simulation tools in different technical domains. At the same time, the interest of the building community to high performance buildings has also strengthened the interest on Life Cycle performances of such buildings, due to the reduction in their operational stage impacts. In this context, the paper proposes an integration of building simulation and Life Cycle Assessment through the programming of a TRNSYS component. It can perform Life Cycle Assessment studies, while having as output as well energy balances and energy and environmental payback times. Currently, the tool is …
SADmote: A Robust and Cost-Effective Device for Environmental Monitoring
2012
Time to deployment for wireless sensor networks could be reduced by using commercial sensor nodes. However, this may lead to suboptimal flexibility, power consumption and cost of the system. Our pilot deployment for precision agriculture and fruit growing research showed similar conclusions and outlined the design decisions leading to SADmote: a new sensor node for environmental monitoring. It was evaluated both in the lab and field, showing improved energy consumption over commercial solutions such as Tmote Sky and Waspmote.
Content quality assessment and acceptance testing in location‐based services
2006
In this paper, we develop and evaluate an approach to assessing the content quality in a location‐based service (LBS). The proposed approach, instead of assessing the quality in absolute terms such as completeness or accuracy, measures the effect that the imperfection of the content is having on the reliability of that specific LBS. We apply the basic ideas from Software Reliability Engineering (SRE), but develop a modification of SRE, 2‐Branch, in order to separate content quality from other factors, such as positioning imprecision, and to reduce the measurement error. In our experimental study, we first compare 2‐Branch to the standard SRE, after which we experimentally analyze some prope…
Time Dependent Deterioration of the X-Ray Dental Diagnostic Equipment
2013
Modern dental X-ray examinations are essential for diagnosis. The goal of this paper is to demonstrate time dependent behavior of dose providing parameters, which help to determine equipment’s age effects on the x-ray machine parameters. Also the comparisons between two different dental X-ray generator equipment types half-period and high frequency was made.
Risk assessment of component failure modes and human errors using a new FMECA approach: application in the safety analysis of HDR brachytherapy
2014
Failure mode, effects and criticality analysis (FMECA) is a safety technique extensively used in many different industrial fields to identify and prevent potential failures. In the application of traditional FMECA, the risk priority number (RPN) is determined to rank the failure modes; however, the method has been criticised for having several weaknesses. Moreover, it is unable to adequately deal with human errors or negligence. In this paper, a new versatile fuzzy rule-based assessment model is proposed to evaluate the RPN index to rank both component failure and human error. The proposed methodology is applied to potential radiological over-exposure of patients during high-dose-rate brach…
Hazards That Can Affect CNC Machine Tools during Operation—An AHP Approach
2020
CNC (computer numerically controlled) machine tools are highly advanced technological systems, used to machine parts by means of metal cutting processes. Their structure and kinematics are very complex, involving accurate coordinated motions on three to five axes. Operating CNC machine tools is a complicated process, which can easily be affected by errors. Nowadays, safety systems and devices are developed in order to make this process safer and more user friendly. Modern CNC controllers are designed to deal with obvious sources of hazards, such as overloads (by means of various sensor systems) and collisions (by checking the NC code syntax and simulating it on the machine). However, despit…
Safety study of an LNG regasification plant using an FMECA and HAZOP integrated methodology
2015
Abstract A safety analysis was performed to determine possible accidental events in the storage system used in the liquefied natural gas regasification plant using the integrated application of failure modes, effects and criticality analysis (FMECA) and hazard and operability analysis (HAZOP) methodologies. The goal of the FMECA technique is the estimation of component failure modes and their major effects, whereas HAZOP is a structured and systematic technique that provides an identification of the hazards and the operability problems using logical sequences of cause-deviation-consequence of process parameters. The proposed FMECA and HAZOP integrated analysis (FHIA) has been designed as a …
Integration of interlock system analysis with automated HAZOP analysis
2001
Abstract The paper details the integration of a method for the analysis of interlock systems with a software support system for HAZOP analysis. The proposed software aims to enhance the potential of HAZOP in terms of depth and efficiency of the analysis. This enhancement is reached through the continuation of the hazard and operability analysis, limited to a group of events which may hold high risks for the plant and/or surrounding environment. The analysis technique of the emergency interlock systems and other plant protection measures proposed by the Center for Chemical Process Safety (CCPS) of the American Institution of Chemical Engineers (AIChE) has been assumed as a starting point. Th…
Automating HAZOP analysis of batch processes
1999
Abstract A support system for the hazard and operabilty studies of batch processes is presented. The search of causes and consequences is automatically performed using similar qualitative models, in form of logic minitrees, for the phases of the operation procedure and the equipment units. More models are considered for the equipment units, one for each subtask in wich they are involved. The search algorithm is integrated by rules for subdividing the plant to be analysed in nodes.
Improving checkpointing intervals by considering individual job failure probabilities
2021
Checkpointing is a popular resilience method in HPC and its efficiency highly depends on the choice of the checkpoint interval. Standard analytical approaches optimize intervals for big, long-running jobs that fail with high probability, while they are unable to minimize checkpointing overheads for jobs with a low or medium probability of failing. Nevertheless, our analysis of batch traces of four HPC systems shows that these jobs are extremely common.We therefore propose an iterative checkpointing algorithm to compute efficient intervals for jobs with a medium risk of failure. The method also supports big and long-running jobs by converging to the results of various traditional methods for…