In the context of the paper, a research work is shown to implement a networked decentralized safety architecture that replaces the central architecture. Thus, the safety system fits better into the rest of the automation structure. On the one hand, this is done by a clearer hardware structure, as there is now one safety controller per decentralized unit, which, analogous to the distributed automation system, communicates with the other stations via an Ethernet-based bus system, thus greatly reducing the wiring and commissioning effort. On the other hand, the decentralized processing allows a local shutdown of the safety-relevant components and an escalation of the emergency shutdown to other areas, depending on the emergency stop situation. This means that in the event of a safety-critical situation, the shutdown is reduced to what is necessary from a safety point of view, which increases system availability.

Com o objetivo da redução do tempo de desenvolvimento de produtos comerciais, hardwares padronizados, como microcontroladores e microprocessadores dedicados, têm sido largamente empregados em aplicações críticas, transferindo para o software elementos até então de responsabilidade exclusiva do hardware. Técnicas de programação defensiva são mecanismos preventivos contra a ocorrência de falhas de hardware ou de software. Para a verificação da segurança de sistemas de aplicações críticas, técnicas de injeção de falhas foram desenvolvidas, propiciando o teste dos mecanismos de tolerância a falhas em condições muito semelhantes às do ambiente operacional real. A introdução de técnicas de programação defensiva aumenta a segurança dos sistemas de aplicações críticas. Não há, na literatura pesquisada, qualquer referência a uma avaliação quantitativa das técnicas de programação defensiva. Esta tese é a descrição de um trabalho experimental, que visa esta avaliação quantitativa, e se organiza em algumas etapas. Primeiro, algumas técnicas de programação defensiva são apresentadas, caracterizadas e eleitas como objeto de avaliação. A seguir, técnicas de injeção de falhas são descritas e uma delas é eleita como meio de teste do trabalho experimental. A partir daí, as técnicas de programação defensiva são verificadas sob o enfoque da técnica de injeção de falhas escolhida. O resultado é uma avaliação quantitativa relativa da eficácia de algumas técnicas de programação defensiva na capacidade de tolerância a falhas inseguras de sistemas de aplicações críticas. Ao final, indicações de continuidade do trabalho são apresentadas. O ambiente metroferroviário, em que trabalha o autor, foi utilizado como estudo de caso. Entretanto, as considerações e conclusões desta tese se aplicam a qualquer sistema de missão critica. / Aiming the reduction of commercial systems` time to the market, standardized hardware, as microcontrollers and embedded microprocessors, has been broadly employed for critical applications, transferring to the software issues that once exclusively relied on the hardware design. Defensive programming techniques are preventive engines against hardware and software faults. In order to verify the safety of critical application systems, fault injection techniques were developed, allowing for the testing of fault tolerant techniques under conditions quite close to actual operational environments. The introduction of defensive programming techniques increases the safety of critical application systems. There are no references, on a large research base, on quantitative evaluations of defensive programming techniques. This thesis describes an experimental work towards a relative quantitative evaluation, organized in a few stages. First, some defensive programming techniques are shown, characterized and selected as the evaluation target. Following, fault injection techniques are described and one of them is selected as the agent of the experimental work. From this point on, the defensive programming techniques are verified under the fault injection technique chosen. The result is a relative quantitative evaluation on the efficiency of some defensive programming techniques on the unsafe fault tolerance capacity of critical application systems. Finally, indications for further work are presented. The railway environment, where the author works, was employed as a case study. However, the reasoning and the conclusions of this thesis are applicable to any critical mission system.

With increasingly complex safety-critical systems like healthcare being developed and managed, there is a need for a tool that allows us to understand their complexity, design better strategies and guide effective change. System dynamics (SD) has been widely used in modelling across a range of applications from socio-economic to engineering systems, but its potential has not yet been fully realised as a tool for understanding trade-off dynamics between safety and efficiency in healthcare. SD has the potential to provide balanced and trustworthy insights into strategic decision making. Participatory SD modelling and learning is particularly important in healthcare since problems in healthcare are difficult to comprehend due to complexity, involvement of multiple stakeholders in decision making and fragmented structure of delivery systems. Participatory SD modelling triangulates stakeholder expertise, data and simulation of implementation plans prior to attempting change. It provides decision-makers with an evaluation and learning tool to analyse impacts of changes and determine which input data is most likely to achieve desired outcomes. This thesis aims to examine the feasibility of applying participatory SD modelling approach to safe and efficient staffing level management within hospital pharmacies and to evaluate the utility and usability of participatory SD modelling approach as a learning method. A case study was conducted looking at trade-offs between dispensing backlog (efficiency) and dispensing errors (safety) in a hospital pharmacy dispensary in an English teaching hospital. A participatory modelling approach was employed where the stakeholders from the hospital pharmacy dispensary were engaged in developing an integrated qualitative conceptual model. The model was constructed using focus group sessions with 16 practitioners consisting of labelling and checking practitioners, the literature and hospital pharmacy databases. Based on the conceptual model, a formal quantitative simulation model was then developed using an SD simulation approach, allowing different scenarios and strategies to be identified and tested. Besides the baseline or business as usual scenario, two additional scenarios (hospital winter pressures and various staffing arrangements, interruptions and fatigue) identified by the pharmacist team were simulated and tested using a custom simulation platform (Forio: user-friendly GUI) to enable stakeholders to play out the likely consequences of the intervention scenarios. We carried out focus group-based survey of 21 participants working in the hospital pharmacy dispensaries to evaluate the applicability, utility and usability of how participatory SD enhanced group learning and building of shared vision for problems within the hospital dispensaries. Findings from the simulation illustrate the knock-on impact rework has on dispensing errors, which is often missing from the traditional linear model-based approaches. This potentially downward-spiral knock-on effect makes it more challenging to deal with demand variability, for example, due to hospital winter pressures. The results provide pharmacy management in-depth insights into potential downward-spiral knock-on effects of high workload and potential challenges in dealing with demand variability. Results and simulated scenarios reveal that it is better to have a fixed adequate staff number throughout the day to keep backlog and dispensing errors to a minimum than calling additional staff to combat growing backlog; and that whilst having a significant amount of trainees might be cost efficient, it has a detrimental effect on dispensing errors (safety) as number of rework done to correct the errors increases and contributes to the growing backlog. Finally, capacity depletion initiated by high workload (over 85% of total workload), even in short bursts, has a significant effect on the amount of rework. Evaluative feedback revealed that participatory SD modelling can help support consensus agreement, thus gaining a deeper understanding of the complex interactions in the systems they strive to manage. The model introduced an intervention to pharmacy management by changing their mental models on how hospital winter pressures, various staffing arrangements, interruptions and fatigue affect productivity and safety. Although the outcome of the process is the model as an artefact, we concluded that the main benefit is the significant mental model change on how hospital winter pressures, various staffing arrangements, interruptions and fatigue are interconnected, as derived from participants involvement and their interactions with the GUI scenarios. The research contributes to the advancement of participatory SD modelling approach within healthcare by evaluating its utility and usability as a learning method, which until recently, has been dominated by the linear reductionist approaches. Methodologically, this is one of the few studies to apply participatory SD approach as a modelling tool for understanding trade-offs dynamics between safety and efficiency in healthcare. Practically, this research provides stakeholders and managers, from pharmacists to managers the decision support tools in the form of a GUI-based platform showcasing the integrated conceptual and simulation model for staffing level management in hospital pharmacy.

Com o objetivo da redução do tempo de desenvolvimento de produtos comerciais, hardwares padronizados, como microcontroladores e microprocessadores dedicados, têm sido largamente empregados em aplicações críticas, transferindo para o software elementos até então de responsabilidade exclusiva do hardware. Técnicas de programação defensiva são mecanismos preventivos contra a ocorrência de falhas de hardware ou de software. Para a verificação da segurança de sistemas de aplicações críticas, técnicas de injeção de falhas foram desenvolvidas, propiciando o teste dos mecanismos de tolerância a falhas em condições muito semelhantes às do ambiente operacional real. A introdução de técnicas de programação defensiva aumenta a segurança dos sistemas de aplicações críticas. Não há, na literatura pesquisada, qualquer referência a uma avaliação quantitativa das técnicas de programação defensiva. Esta tese é a descrição de um trabalho experimental, que visa esta avaliação quantitativa, e se organiza em algumas etapas. Primeiro, algumas técnicas de programação defensiva são apresentadas, caracterizadas e eleitas como objeto de avaliação. A seguir, técnicas de injeção de falhas são descritas e uma delas é eleita como meio de teste do trabalho experimental. A partir daí, as técnicas de programação defensiva são verificadas sob o enfoque da técnica de injeção de falhas escolhida. O resultado é uma avaliação quantitativa relativa da eficácia de algumas técnicas de programação defensiva na capacidade de tolerância a falhas inseguras de sistemas de aplicações críticas. Ao final, indicações de continuidade do trabalho são apresentadas. O ambiente metroferroviário, em que trabalha o autor, foi utilizado como estudo de caso. Entretanto, as considerações e conclusões desta tese se aplicam a qualquer sistema de missão critica. / Aiming the reduction of commercial systems` time to the market, standardized hardware, as microcontrollers and embedded microprocessors, has been broadly employed for critical applications, transferring to the software issues that once exclusively relied on the hardware design. Defensive programming techniques are preventive engines against hardware and software faults. In order to verify the safety of critical application systems, fault injection techniques were developed, allowing for the testing of fault tolerant techniques under conditions quite close to actual operational environments. The introduction of defensive programming techniques increases the safety of critical application systems. There are no references, on a large research base, on quantitative evaluations of defensive programming techniques. This thesis describes an experimental work towards a relative quantitative evaluation, organized in a few stages. First, some defensive programming techniques are shown, characterized and selected as the evaluation target. Following, fault injection techniques are described and one of them is selected as the agent of the experimental work. From this point on, the defensive programming techniques are verified under the fault injection technique chosen. The result is a relative quantitative evaluation on the efficiency of some defensive programming techniques on the unsafe fault tolerance capacity of critical application systems. Finally, indications for further work are presented. The railway environment, where the author works, was employed as a case study. However, the reasoning and the conclusions of this thesis are applicable to any critical mission system.

published_or_final_version / Electrical Engineering / Master / Master of Philosophy

När problem med materielsystem upptäcks efter att de har levererats till Försvarsmakten så är detden vidmakthållande organisationen som tar hand om det. Den arbetar för att det aktuella problemetåtgärdas och även förebygger liknande problem. Många instanser runt om i Försvarsmakten är inblandadei arbetet; ibland kan samordning och kommunikation vara ett problem för verksamheten. Uppsatsen undersöker hur ett datorbaserat samarbetssystem kan bidra till att förbättra den vidmakthållandeprocessen inom Försvarsmakten. Undersökningen visar att ett datorbaserat samarbetssystem kan underlätta arbetet för en idag redanfungerande vidmakthållandeorganisation. / When problems with materiel are found after being delivered to the Swedish Armed Forces it is the maintaining organization that handles it. It sees to that the current problem is fixed and that similar problems are prevented. Many competent bodies in the Swedish Armed Forces are in-volved in the work, and therefore co-ordination and communication can be a problem for the activities. This thesis will investigate how a computer based co-operation system can simplify the maintain-ing process in the Swedish Armed Forces. The study shows that a computer based co-operation system can contribute to the process in a today functional maintaining organization.

Orientador: Jacques Wainer / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-18T13:39:01Z (GMT). No. of bitstreams: 1 Bezerra_FabiodeLima_D.pdf: 910682 bytes, checksum: 03039d80da140539552895720627ea23 (MD5) Previous issue date: 2011 / Resumo: Atualmente há uma variedade de sistemas que apóiam processos de negócio (ex. WfMS, CRM, ERP, SCM, etc). Muitos desses sistemas possuem uma forte característica de coordenação das atividades dos processos de negócios, garantindo que essas atividades sejam executadas como especificadas no modelo de processo. Entretanto, há domínios com maior necessidade de flexibilidade na execução desses processos, por exemplo, em atendimento hospitalar, cuja conduta pode variar para cada paciente. Essa característica desses domínios demanda o desenvolvimento de sistemas orientados a processos fracamente definidos, ou com execução mais flexível. Nesses domínios, a execução de algumas atividades comuns pode ser violada, ou a execução de uma atividade "incomum" pode ser necessária, ou seja, tais processos são suscetíveis a execuções excepcionais ou mesmo fraudulentas. Assim, o provimento de flexibilidade não pode ser considerado sem melhorar as questões relacionadas a segurança, pois flexibilidade e segurança são requisitos claramente conflitantes. Portanto, é necessário desenvolver mecanismos ou métodos que permitam a conjugação desses dois requisitos em um mesmo sistema, promovendo um balanço entre flexibilidade e segurança. Esta tese tem por objetivo projetar, implementar e avaliar métodos de detecção de anomalias em logs de sistemas de apoio a processos de negócios, ou seja, o desenvolvimento de métodos utilizados para descobrir quais instâncias de processos podem ser uma excução anômala. Desta forma, através da integração de um método de detecção de anomalias com um sistema de apoio à processos de negócio, tais sistemas poderão oferecer um ambiente de execução flexível, mas capaz de identificar execuções anômalas que podem indicar desde uma execução excepcional, até uma tentativa de fraude. Assim, o estudo de métodos de detecção de eventos anômalos vem preencher um espaço pouco explorado pela comunidade de process mining, que tem demonstrado maior interesse em entender o comportamento comum em processos de negócios. Entretanto, apesar desta tese não discutir o significado das instâncias anômalas, os métodos de detecção apresentados aqui são importantes porque permitem selecionar essas instâncias / Abstract: Nowadays, many business processes are supported by information systems (e.g. WfMS, CRM, ERP, SCM, etc.). Many of these systems have a strong characteristic of coordination of activities defined in the business processes, mainly for ensuring that these activities are performed as specified in the process model. However, there are domains that demand more flexible systems, for example, hospital and health domains, whose behavior can vary for each patient. Such domains of applications require an information system in which the business processes are weakly defined, supporting more flexible and dynamic executions. For example, the execution of some common activities may be violated, or some unusual activity may be enforced for execution. Therefore, in domains of applications in which the systems support a high level of flexibility the business processes are susceptible to exceptional or even fraudulent executions. Thus, the provision of flexibility can not be considered without improving the security issues, since there is clearly a trade-off between flexibility and security requirements. Therefore, it is necessary to develop a mechanism to allow the combination of these two requirements in a system, that is, a mechanism that promotes a balance between flexibility and security. This thesis aims to design, implement and evaluate methods for detecting anomalies in logs of process-aware information systems, that is, the development of methods to find out which process instances may be an anomalous execution. Thus, when incorporating a method for detecting anomalies in such systems, it would be possible to offer a flexible and safer execution environment, since the system is also able to identify anomalous executions, which could be a simple exception or a harmful fraud attempt. Thus, the study of methods for detecting anomalous events will fill an area largely unexplored by the community of process mining, which has been mainly interested in understanding the common behavior in business processes. Furthermore, although this thesis does not discuss the meaning of an anomalous instance, the methods and algorithms presented here are important because they allow us to identify those instances / Doutorado / Ciência da Computação / Doutor em Ciência da Computação

Construction worker safety is normally a construction activity in the United States, even though there is an emerging body of literature discussing the positive effects of considering safety earlier in the construction lifecycle.  This literature has discussed the fragmentation in terms of safety attitudes between owners and designers and those carrying out the construction of a project.  Quantitatively identifying the specific areas that the differences exist in terms of safety attitudes between common roles on a construction project could be a step toward reducing the fragmentation that currently exists in the work system and promoting safety to be more of a consideration earlier in the project lifecycle.  One common technique for measuring safety attitudes is the use of safety climate survey instruments, but in the construction industry these have historically focused on just construction personnel.  This research will discuss the development of a survey instrument to measure differences in safety attitudes between typical members of the entire construction project work system in order to identify specific areas that gaps exist.  Phase I of the research include the development of an instrument using Mohammed\'s (2002) survey as a base, validation of the measurement model using Confirmatory Factor Analysis, and using applied nonparametric statistics to analyze the data and identify significant differences.  These results will be used in Phase II to develop a training tool to educate relevant project personnel on differences that were identified in Phase I, and to determine the best mediums for conveying this type of information. / Ph. D.

Smart grids representam o futuro das redes elétricas. Estes tipos de redes devem ser robustas a flutuações de carga e devem possuir monitoramento e gerenciamento inteligente e em tempo real. Para que essas demandas sejam possíveis, é preciso uma comunicação de dados de alta velocidade, flexível e de baixo custo. Dentro dessas características, muitos autores propõem a utilização de sistemas de comunicação sem fio, os quais possuem um custo de implantação mais baixo que redes ópticas ou cabeadas, além de possuir flexibilidade para rápidas mudanças de topologia, e não apresentarem barreiras em relação aos padrões e equipamentos, o oposto por exemplo ao caso do sistema PLC (Power Line Communications). Devido à natureza difusora do canal sem fio, segurança nesse tipo de rede é um dos pontos mais críticos, já que um ataque de qualquer natureza pode provocar perturbações e blackouts na rede elétrica, ou gerar problemas de privacidade, na situação em que atacantes passivos (eavesdroppers) interceptam mensagens da rede com o intuito de obter algum tipo de benefício. Esta segunda situação, de ataques passivos, será abordada neste trabalho. Além das tradicionais técnicas de criptografia geralmente utilizadas para aumentar a segurança de redes de comunicação, outra área que vem recentemente despertando interesse da comunidade científica é a área de segurança na camada física, a qual é baseada em conceitos da teoria da informação de Shannon. Neste trabalho, utiliza-se as técnicas de codificação de rede para aumentar a segurança na camada física da parte de múltiplo acesso de uma rede de comunicação sem fio, em que dois transmissores possuem informações independentes para um destino em comum, na presença de um eavesdropper. Utilizando-se a probabilidade de outage com restrições de sigilo como métrica, mostra-se através de resultados analíticos e numéricos que o sigilo pode ser aumentado através da codificação de rede, quando comparada com a transmissão direta e com as técnicas de cooperação tradicionais. / Smart grids represent future of electrical power systems . These kind of networks must be robust to load fluctuations as well as have smart monitoring and intelligent management in real-time fashion . Based on the aforementioned needs, many authors propose the use of wireless communication systems in order to meet these demands, due to their efficient tradeoff between low-cost and high-seed when compared to wired connections such as optical fibens or metallic cables, and, in addition, they are flexible to topology changes and do not have constrainsts in terms of standards and devices, the opposite for example to the case of PLC(Power Line Comminications) .Due to the broadcast nature of the wireless medium , security is onde of the critical issues in smart grids since the occurrence of attacks can lead to load fluctuations and blackouts in the electrical system, or generate secrecy problems, in the situation where passive eaversdroppers intercept messages in the network aiming to obtain some kind of benefit . This second case of passive attacks will be addressed in the work. In addition to classical cryptography strategies commonly used to increase the security in communications systems another area which has been studied by the scientific community is the physical-layer security, which is based on the Shannon’s information theory. In this work, we use the network coding technique as tool to increase the physical-layer in a mulple access wireless network, where two users have independent information to transmit to a common destination, in the presence of an eavesdropper. By using the secrecy outage probability as the metric, we show through theoretic and numerical results that the network security can be increased through the use of network coding when compared to the transmission and traditional cooperative techniques.

Smart grids representam o futuro das redes elétricas. Estes tipos de redes devem ser robustas a flutuações de carga e devem possuir monitoramento e gerenciamento inteligente e em tempo real. Para que essas demandas sejam possíveis, é preciso uma comunicação de dados de alta velocidade, flexível e de baixo custo. Dentro dessas características, muitos autores propõem a utilização de sistemas de comunicação sem fio, os quais possuem um custo de implantação mais baixo que redes ópticas ou cabeadas, além de possuir flexibilidade para rápidas mudanças de topologia, e não apresentarem barreiras em relação aos padrões e equipamentos, o oposto por exemplo ao caso do sistema PLC (Power Line Communications). Devido à natureza difusora do canal sem fio, segurança nesse tipo de rede é um dos pontos mais críticos, já que um ataque de qualquer natureza pode provocar perturbações e blackouts na rede elétrica, ou gerar problemas de privacidade, na situação em que atacantes passivos (eavesdroppers) interceptam mensagens da rede com o intuito de obter algum tipo de benefício. Esta segunda situação, de ataques passivos, será abordada neste trabalho. Além das tradicionais técnicas de criptografia geralmente utilizadas para aumentar a segurança de redes de comunicação, outra área que vem recentemente despertando interesse da comunidade científica é a área de segurança na camada física, a qual é baseada em conceitos da teoria da informação de Shannon. Neste trabalho, utiliza-se as técnicas de codificação de rede para aumentar a segurança na camada física da parte de múltiplo acesso de uma rede de comunicação sem fio, em que dois transmissores possuem informações independentes para um destino em comum, na presença de um eavesdropper. Utilizando-se a probabilidade de outage com restrições de sigilo como métrica, mostra-se através de resultados analíticos e numéricos que o sigilo pode ser aumentado através da codificação de rede, quando comparada com a transmissão direta e com as técnicas de cooperação tradicionais. / Smart grids represent future of electrical power systems . These kind of networks must be robust to load fluctuations as well as have smart monitoring and intelligent management in real-time fashion . Based on the aforementioned needs, many authors propose the use of wireless communication systems in order to meet these demands, due to their efficient tradeoff between low-cost and high-seed when compared to wired connections such as optical fibens or metallic cables, and, in addition, they are flexible to topology changes and do not have constrainsts in terms of standards and devices, the opposite for example to the case of PLC(Power Line Comminications) .Due to the broadcast nature of the wireless medium , security is onde of the critical issues in smart grids since the occurrence of attacks can lead to load fluctuations and blackouts in the electrical system, or generate secrecy problems, in the situation where passive eaversdroppers intercept messages in the network aiming to obtain some kind of benefit . This second case of passive attacks will be addressed in the work. In addition to classical cryptography strategies commonly used to increase the security in communications systems another area which has been studied by the scientific community is the physical-layer security, which is based on the Shannon’s information theory. In this work, we use the network coding technique as tool to increase the physical-layer in a mulple access wireless network, where two users have independent information to transmit to a common destination, in the presence of an eavesdropper. By using the secrecy outage probability as the metric, we show through theoretic and numerical results that the network security can be increased through the use of network coding when compared to the transmission and traditional cooperative techniques.