Metodologia integrada para mapeamento de falhas: uma proposta de utilização conjunta do mapeamento de processos com as técnicas FTA, FMEA e a análise crítica de especialistas

As falhas representam não conformidades nas atividades produtivas, de tal modo que pesquisas para seu controle e prevenção são, no mínimo, desejáveis. Na literatura sobre o assunto, observa-se uma gama variada de técnicas, porém, quase sempre, usadas isoladamente e, em poucos casos, no setor de serviços. Observando essa lacuna, propõe-se uma metodologia de Mapeamento de Falhas que integra diferentes abordagens que se complementam, aproveitando-se o potencial e o benefício de cada técnica para análise e controle de falhas. Para a consecução dessa proposta, efetuou-se uma pesquisa bibliográfica para conceituação e entendimento das técnicas utilizadas, um estudo e análise de integração dessas técnicas e, por fim, um exemplo real de aplicação em processo notarial de serviço, tema este ainda não explorado na literatura pertinente e, portanto, bastante auspicioso. Como resultado, observa-se uma ferramenta que permite uma visualização completa e objetiva das atividades desencadeadas pelos processos, seus pontos críticos e suas potenciais falhas, podendo ser aplicada com propriedade em empresas de prestação de serviços.

Análise da aplicabilidade da ferramenta FTA no estudo de falhas de manutenção em uma indústria

The competitiveness in the industrial sector is increasingly fierce. In this context, the quality of maintenance is often neglected due to the sense of urgency that arises in these companies. Thus, it becomes increasingly necessary to use tools of Reliability Centered Maintenance to assist in managing maintenance effectively and efficiently, and directing resources .This study aims to evaluate the use of the fault tree to identify critical paths in the maintenance sector in an industry. The proposal is uses the tools of Reliability Centered Maintenance (MCC) for the collection, disposal and prioritizing causes problems in the transport industry. The study has its focus on the theoretical foundation of problem solving methods and techniques to identify the root causes, using the fault tree

Beiträge zur Chemie der schwersten Elemente in den Bereichen Elektrochemie und Chromatographie

Im Rahmen dieser Arbeit wurden Experimente auf verschiedenen Gebieten der chemischen Charakterisierung der schwersten Elemente durchgeführt. So wurden Vorarbeiten zur Elektrochemie der superschweren Elemente geleistet. Hier konnte gezeigt werden, dass sich Po aus verdünnten Säuren auf Metallelektroden spontan abscheiden lässt. Als wichtigste Reaktionsparameter wurden Temperatur, Konvektion und Viskosität des Elektrolyten identifiziert. Für die Elektrodeposition ist es von Bedeutung, reproduzierbar saubere Elektroden einzusetzen. Auch hierzu konnten Erkenntnisse gewonnen werden. Auf dem Gebiet der Charakterisierung von Nukliden wurde der Elektroneneinfang in Db-263 untersucht. Aus diesem Zerfall geht Rf-263 hervor, welches mit einer Halbwertszeit von 15min überwiegend durch Spontanspaltung zerfällt. Im Experiment wurde Rf-263 mittels Ionenaustauschchromatographie und nachfolgender Flüssig-Flüssig-Extraktion von Db und Aktiniden getrennt. Das erhaltene Präparat wurde auf Alpha-Zerfall und Spontanspaltung untersucht. Die Zahl der Rf-263 Zerfälle lässt auf einen Zerfallszweig durch Elektroneneinfang in Db-263 von 3% schließen. Ein Großteil der Arbeit beschäftigt sich mit der Bestimmung des Kd-Wertes von Sg am Anionenaustauscher Aminex A27 in 0.1M HNO3/5E-3M HF. Beim mit dem ALOHA-System durchgeführten Experiment wurde die Mehrsäulentechnik (MCT) erstmals für die wässrige Chemie von Sg genutzt. Aufgrund zahlreicher Probleme konnte letztlich kein Kd-Wert bestimmt werden. Stattdessen wurde das Experiment einer Fehleranalyse unterzogen. Hier zeigte sich eine Anfälligkeit der MCT auf natürliche Radionuklide. Weiterhin konnten Probleme bei ALOHA aufgedeckt werden, die eine Wiederholung des Experiments ausschlossen. In der Folge wurde ein alternativer Anionenaustauscher charakterisiert, sowie die Elektrolysebedingungen, als wichtiger Schritt der chemischen Aufarbeitung bei der MCT, genauer spezifiziert.

Analisi dei guasti di impianti di vaporizzazione di azoto ed aria compressa

Nel corso degli ultimi decenni, ha assunto importanza crescente il tema della sicurezza e dell’affidabilità degli impianti dell’industria di processo. Tramite l’analisi di affidabilità è possibile individuare i componenti critici di un impianto più a rischio. Nel presente lavoro di tesi è stata eseguita l’analisi di affidabilità di tre impianti dello stabilimento SOL di Mantova: l’impianto di vaporizzazione azoto a bassa pressione, l’impianto di vaporizzazione azoto a media pressione e l’impianto di produzione di aria sintetica. A partire dai diagrammi P&ID degli impianti si è effettuata l’analisi delle possibili modalità di guasto degli impianti stessi tramite la tecnica FMECA, acronimo di Failure Modes & Effects Criticality Analisys. Una volta definite le modalità di guasto degli impianti, si è proceduto a quantificarne l’affidabilità utilizzando la tecnica FTA, acronimo di Fault Tree Analisys. I risultati ottenuti dall’analisi degli alberi dei guasti, hanno permesso di individuare gli eventi primari che maggiormente contribuiscono al fallimento dei sistemi studiati, consentendo di formulare ipotesi per l’incremento di affidabilità degli impianti.

A simplified Probabilistic Safety Assesment of a Steam-Methane Reforming Hydrogen Production Plant coupled to a High-Temperature Gas Cooled Nuclear Reactor

A Probabilistic Safety Assessment (PSA) is being developed for a steam-methane reforming hydrogen production plant linked to a High-Temperature Gas Cooled Nuclear Reactor (HTGR). This work is based on the Japan Atomic Energy Research Institute’s (JAERI) High Temperature Test Reactor (HTTR) prototype in Japan. This study has two major objectives: calculate the risk to onsite and offsite individuals, and calculate the frequency of different types of damage to the complex. A simplified HAZOP study was performed to identify initiating events, based on existing studies. The initiating events presented here are methane pipe break, helium pipe break, and PPWC heat exchanger pipe break. Generic data was used for the fault tree analysis and the initiating event frequency. Saphire was used for the PSA analysis. The results show that the average frequency of an accident at this complex is 2.5E-06, which is divided into the various end states. The dominant sequences result in graphite oxidation which does not pose a health risk to the population. The dominant sequences that could affect the population are those that result in a methane explosion and occur 6.6E-8/year, while the other sequences are much less frequent. The health risk presents itself if there are people in the vicinity who could be affected by the explosion. This analysis also demonstrates that an accident in one of the plants has little effect on the other. This is true given the design base distance between the plants, the fact that the reactor is underground, as well as other safety characteristics of the HTGR. Sensitivity studies are being performed in order to determine where additional and improved data is needed.

Environmental risk assessment in open pit blasting operations: compliance with ISO 31010:2010

All activities of an organization involve risks that should be managed. The risk management process aids decision making by taking account of uncertainty and the possibility of future events or circumstances (intended or unintended) and their effects on agreed objectives. With that idea, new ISO Standard has been drawn up. ISO 31010 has been recently issued which provides a structured process that identifies how objectives may be affected, and analyses the risk in term of consequences and their probabilities before deciding on whether further treatment is required. In this lecture, that ISO Standard has been adapted to Open Pit Blasting Operations, focusing in Environmental effects which can be managed properly. Technique used is Fault Tree Analysis (FTA), which is applied in all possible scenarios, providing to Blasting Professionals the tools to identify, analyze and manage environmental effects in blasting operations. Also this lecture can help to minimize each effect, studying each case. This paper also can be useful to Project Managers and Occupational Health and Safety Departments (OH&S) because blasting operations can be evaluated and compared one to each other to determine the risks that should be managed in different case studies. The environmental effects studied are: ground vibrations, flyrock and air overpressure (airblast). Sometimes, blasting operations are carried out near populated areas where environmental effects may impose several limitations on the use of explosives. In those cases, where these factors approach certain limits, National Standards and Regulations have to be applied.

Desenvolvimento de um método para diagnose de falhas na operação de navios transportadores de gás natural liquefeito através de redes bayesianas.

O Gás Natural Liquefeito (GNL) tem, aos poucos, se tornado uma importante opção para a diversificação da matriz energética brasileira. Os navios metaneiros são os responsáveis pelo transporte do GNL desde as plantas de liquefação até as de regaseificação. Dada a importância, bem como a periculosidade, das operações de transporte e de carga e descarga de navios metaneiros, torna-se necessário não só um bom plano de manutenção como também um sistema de detecção de falhas que podem ocorrer durante estes processos. Este trabalho apresenta um método de diagnose de falhas para a operação de carga e descarga de navios transportadores de GNL através da utilização de Redes Bayesianas em conjunto com técnicas de análise de confiabilidade, como a Análise de Modos e Efeitos de Falhas (FMEA) e a Análise de Árvores de Falhas (FTA). O método proposto indica, através da leitura de sensores presentes no sistema de carga e descarga, quais os componentes que mais provavelmente estão em falha. O método fornece uma abordagem bem estruturada para a construção das Redes Bayesianas utilizadas na diagnose de falhas do sistema.

Development of a systems risk methodology for single and multi-modal transportation systems. Final report.

Transportation Department, Research and Special Programs Administration, Washington, D.C.

Transportation system safety methodology. First year final report.

Transportation Department, Office of University Research, Washington, D.C.

Reliability analysis for hazard and operability studies

Fault tree analysis is used as a tool within hazard and operability (Hazop) studies. The present study proposes a new methodology for obtaining the exact TOP event probability of coherent fault trees. The technique uses a top-down approach similar to that of FATRAM. This new Fault Tree Disjoint Reduction Algorithm resolves all the intermediate events in the tree except OR gates with basic event inputs so that a near minimal cut sets expression is obtained. Then Bennetts' disjoint technique is applied and remaining OR gates are resolved. The technique has been found to be appropriate as an alternative to Monte Carlo simulation methods when rare events are countered and exact results are needed. The algorithm has been developed in FORTRAN 77 on the Perq workstation as an addition to the Aston Hazop package. The Perq graphical environment enabled a friendly user interface to be created. The total package takes as its input cause and symptom equations using Lihou's form of coding and produces both drawings of fault trees and the Boolean sum of products expression into which reliability data can be substituted directly.

Apollo 13 Risk Assessment Revisited

Fault tree methodology is the most widespread risk assessment tool by which one is able to predict - in principle - the outcome of an event whenever it is reduced to simpler ones by the logic operations conjunction and disjunction according to the basics of Boolean algebra. The object of this work is to present an algorithm by which, using the corresponding computer code, one is able to predict - in practice - the outcome of an event whenever its fault tree is given in the usual form.

Metodologia para análise da dependabilidade de Smart Grids

Smart Grids are a new trend of electric power distribution, the future of current systems. These networks are continually being introduced in order to improve the reliability of systems, providing alternatives to energy supply and cost savings. Faced with increasing electric power grids complexity, the energy demand and the introduction of alternative sources to energy generation, all components of system require a fully integration in order to achieve high reliability and availability levels (dependability). The systematization of a Smart Grid from the Fault Tree formalism enable the quantitative evaluation of dependability of a specific scenario. In this work, a methodology for dependability evaluation of Smart Grids is proposed. A study of case is described in order to validate the proposal. With the use of this methodology, it is possible to estimate during the early design phase the reliability, availability of Smart Grid beyond to identify the critical points from the failure and repair distributions of components.

Application for fault location in electrical power distribution systems

Fault location has been studied deeply for transmission lines due to its importance in power systems. Nowadays the problem of fault location on distribution systems is receiving special attention mainly because of the power quality regulations. In this context, this paper presents an application software developed in Matlabtrade that automatically calculates the location of a fault in a distribution power system, starting from voltages and currents measured at the line terminal and the model of the distribution power system data. The application is based on a N-ary tree structure, which is suitable to be used in this application due to the highly branched and the non- homogeneity nature of the distribution systems, and has been developed for single-phase, two-phase, two-phase-to-ground, and three-phase faults. The implemented application is tested by using fault data in a real electrical distribution power system

Fat-Tree Routing for Transit

The Transit network provides high-speed, low-latency, fault-tolerant interconnect for high-performance, multiprocessor computers. The basic connection scheme for Transit uses bidelta style, multistage networks to support up to 256 processors. Scaling to larger machines by simply extending the bidelta network topology will result in a uniform degradation of network latency between all processors. By employing a fat-tree network structure in larger systems, the network provides locality and universality properties which can help minimize the impact of scaling on network latency. This report details the topology and construction issues associated with integrating Transit routing technology into fat-tree interconnect topologies.

Application for fault location in electrical power distribution systems

Fault location has been studied deeply for transmission lines due to its importance in power systems. Nowadays the problem of fault location on distribution systems is receiving special attention mainly because of the power quality regulations. In this context, this paper presents an application software developed in Matlabtrade that automatically calculates the location of a fault in a distribution power system, starting from voltages and currents measured at the line terminal and the model of the distribution power system data. The application is based on a N-ary tree structure, which is suitable to be used in this application due to the highly branched and the non- homogeneity nature of the distribution systems, and has been developed for single-phase, two-phase, two-phase-to-ground, and three-phase faults. The implemented application is tested by using fault data in a real electrical distribution power system