<p>More than twenty-five percent of the risk of failure for the 9-1-1 system can be contributed to blocked lines. The second major failure mode is unhelpful or improperly trained telecommunicators. The quick dispatch of emergency response teams in the event of any disaster or accident through the use of the 9-1-1 system is crucial to the well-being of the public. These potential failure modes prevent desperately awaited help from arriving as soon as possible. Therefore, the reliability and effectiveness of the system must be evaluated.</p> <p> The objective of this report is to identify failure modes of the 9-1-1 system, calculate their criticality, prioritize them in order of risk, and propose economical and feasible alternative solutions.</p> <p> Failure mode, effects, and criticality analysis (FMECA) is an evaluation tool that proves extremely useful when a system is desired to be kept highly effective and reliable. In this report, it is applied within the Systems Engineering Process to analyze areas of weakness throughout the New Jersey 9-1-1 system. FMECA is widely used throughout the military and commercial industry. It illustrates the interrelationships between causes and effects of failure modes, and helps to focus attention on high risk areas so that proper precautions may be taken.</p> <p> First, the use of FMECA is reviewed. The step-by-step procedures are next illustrated, and it is noted that FMECA must be tailored to each system relative to its characteristics and desired application. The New Jersey 9-1-1 system is analyzed in detail and is found to be an effective emergency communications network. However, technology has not yet provided solutions to all possible failures. In fact, technology adds to the failure possibilities. Possible future areas of development are included.</p> <p> / Master of Science

This study demonstrates that hybrid methods can be used for measuring the risk severity of technology-induced errors (TIE) that result from use of health information technology (HIT). The objectives of this research study include: 1. Developing an integrated conceptual risk assessment model to measure the risk severity of technology-induced errors. 2. Analyzing the criticality and risk thresholds associated with TIE’s contributing factors. 3. Developing a computer-based simulation model that could be used to undertake various simulations of TIE’s problems and validate the results. Using data from published papers describing three sample problems related to usability and technology-induced errors, hybrid methods were developed for assessing the risk severity and thresholds under various simulated conditions. A risk assessment model (RAM) and its corresponding steps were developed. A computer-based simulation of risk assessment using the model was also developed, and several runs of the simulation were carried out. The model was tested and found to be valid. Based on assumptions and published statistics obtained by publically available databases, we measured the risk severity and analyzed its criticality to classify risks of contributing factors into four different classes. The simulation results validated the efficiency and efficacy of the proposed methods with the sample problems. / Graduate / 0723 / 0680 / 0769 / tschio2011@gmail.com

Les études de sûreté de fonctionnement (SdF) sont en général basées sur l’hypothèse d’indépendance des événements de défaillance et de réparation ainsi que sur l’analyse des coupes qui décrivent les sous-ensembles de composants entraînant la défaillance du système. Dans le cas des systèmes dynamiques pour lesquels l’ordre d’occurrence des événements a une incidence directe sur le comportement dysfonctionnel du système, il est important de privilégier l’utilisation de séquences d’événements permettant une évaluation des indicateurs de SdF plus précise que les coupes. Ainsi, nous avons proposé, dans une première partie de nos travaux, un cadre formel permettant la détermination des séquences d’événements qui décrivent l’évolution du système ainsi que leur évaluation quantitative, en recourant à la théorie de langages probabilistes et à la théorie des processus markoviens/semi-markoviens. L'évaluation quantitative des séquences intègrent le calcul de leur probabilité d'occurrence ainsi que leur criticité (coût et longueur des séquences). Pour l’évaluation des séquences décrivant l’évolution des systèmes complexes présentant plusieurs modes de fonctionnement ou de défaillance, une approche modulaire basée sur les opérateurs de composition (choix et concaténation) a été proposée. Celle-ci consiste à calculer la probabilité d'une séquence d'événements globale à partir d'évaluations réalisées localement, mode par mode. Les différentes contributions sont appliquées sur deux cas d'étude de taille et complexité croissante. / Dependability studies are often based on the assumption of events (failures and repairs) independence but also on the analyse of cut-set which describes the subsets of components causing a system failure. In the case of dynamic systems where the events occurrence order has a direct impact on the dysfunctional behaviour, it is important to promote using event sequences instead of cut-sets for dependability assessment. In the first part, a formal framework is proposed. It helps in determining sequences of events that describe the evolution of the system and their assessment, using the theory of probabilistic languages and the theory of Markov/semi-Markov processes. The assessment integrates the calculation of the probability occurrence of the event sequences and their criticality (cost and length). For the assessment of complex systems with multiple operating/failure modes, a modular approach based on composition operators (choice and concatenation) is proposed. Evaluation of the probability of a global sequence of events is performed from local Markov/semi-Markov models for each mode of the system. The different contributions are applied on two case studies with a growing complexity.