Dissertations / Theses on the topic 'Computer safety'
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1
Simpson, Andrew C. "Safety through security." Thesis, University of Oxford, 1996. http://ora.ox.ac.uk/objects/uuid:4a690347-46af-42a4-91fe-170e492a9dd1.
Abstract:
In this thesis, we investigate the applicability of the process algebraic formal method Communicating Sequential Processes (CSP) [Hoa85] to the development and analysis of safetycritical systems. We also investigate how these tasks might be aided by mechanical verification, which is provided in the form of the proof tool Failures-Divergences Refinement (FDR) [Ros94]. Initially, we build upon the work of [RWW94, Ros95], in which CSP treatments of the security property of non-interference are described. We use one such formulation to define a property called protection, which unifies our views of safety and security. As well as applying protection to the analysis of safety-critical systems, we develop a proof system for this property, which in conjunction with the opportunity for automated analysis provided by FDR, enables us to apply the approach to problems of a sizable complexity. We then describe how FDR can be applied to the analysis of mutual exclusion, which is a specific form of non-interference. We investigate a number of well-known solutions to the problem, and illustrate how such mutual exclusion algorithms can be interpreted as CSP processes and verified with FDR. Furthermore, we develop a means of verifying the faulttolerance of such algorithms in terms of protection. In turn, mutual exclusion is used to describe safety properties of geographic data associated with Solid State Interlocking (SSI) railway signalling systems. We show how FDR can be used to describe these properties and model interlocking databases. The CSP approach to compositionality allows us to decompose such models, thus reducing the complexity of analysing safety invariants of SSI geographic data. As such, we describe how the mechanical verification of Solid State Interlocking geographic data, which was previously considered to be an intractable problem for the current generation of mechanical verification tools, is computationally feasible using FDR. Thus, the goals of this thesis are twofold. The first goal is to establish a formal encapsulation of a theory of safety-critical systems based upon the relationship which exists between safety and security. The second goal is to establish that CSP, together with FDR, can be applied to the modelling of Solid State Interlocking geographic databases. Furthermore, we shall attempt to demonstrate that such modelling can scale up to large-scale systems.
2
Conmy, Philippa Mary. "Safety analysis of computer resource management software." Thesis, University of York, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428494.
3
An, Hong. "Computer-aided applications in process plant safety." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6418.
Abstract:
Process plants that produce chemical products through pre-designed processes are fundamental in the Chemical Engineering industry. The safety of hazardous processing plants is of paramount importance as an accident could cause major damage to property and/or injury to people. HAZID is a computer system that helps designers and operators of process plants to identify potential design and operation problems given a process plant design. However, there are issues that need to be addressed before such a system will be accepted for common use. This research project considers how to improve the usability and acceptability of such a system by developing tools to test the developed models in order for the users to gain confidence in HAZID s output as HAZID is a model based system with a library of equipment models. The research also investigates the development of computer-aided safety applications and how they can be integrated together to extend HAZID to support different kinds of safety-related reasoning tasks. Three computer-aided tools and one reasoning system have been developed from this project. The first is called Model Test Bed, which is to test the correctness of models that have been built. The second is called Safe Isolation Tool, which is to define isolation boundary and identify potential hazards for isolation work. The third is an Instrument Checker, which lists all the instruments and their connections with process items in a process plant for the engineers to consider whether the instrument and its loop provide safeguards to the equipment during the hazard identification procedure. The fourth is a cause-effect analysis system that can automatically generate cause-effect tables for the control engineers to consider the safety design of the control of a plant as the table shows process events and corresponding process responses designed by the control engineer. The thesis provides a full description of the above four tools and how they are integrated into the HAZID system to perform control safety analysis and hazard identification in process plants.
4
Wang, Yuan-Fang. "Computer Vision Analysis for Vehicular Safety Applications." International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596451.
Abstract:
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NVIn this paper, we present our research on using computer-vision analysis for vehicular safety applications. Our research has potential applications for both autonomous vehicles and connected vehicles. In particular, for connected vehicles, we propose three image analysis algorithms that enhance the quality of a vehicle's on-board video before inter-vehicular information exchange takes place. For autonomous vehicles, we are investigating a visual analysis scheme for collision avoidance during back up and an algorithm for automated 3D map building. These algorithms are relevant to the telemetering domain as they involve determining the relative pose between a vehicle and other vehicles on the road, or between a vehicle and its 3D driving environment, or between a vehicle and obstacles surrounding the vehicle.
5
Reyad, Passant. "Application of computer vision techniques in safety diagnosis and evaluation of safety treatments." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59701.
Abstract:
Traditional road safety analysis is usually conducted using historical collision records. This reactive approach to road safety has been shown to have several shortcomings. Recently, there has been significant interest in using surrogate measures such as traffic conflicts to analyze safety. This interest has been strengthened by the availability of tools to automate the traffic conflict analysis from video data. Using automated computer vision techniques, road users can be tracked, classified, and their interactions determined accurately and reliably. This thesis demonstrates two applications of automated road safety analysis techniques using traffic conflicts. The first application is related to the diagnosis of road safety issues. A case study of safety at a school zone in Edmonton, Alberta is used. 240 video-hours of traffic data were recorded in two different seasons. The data was analyzed to evaluate the current safety performance of the school zone to identify factors that may be contributing to safety concerns and to propose potential safety improvements. The analysis included the automated analysis of traffic conflicts, violations, and traffic speed. Several recommendations were presented that would potentially improve the safety for all road users without affecting the mobility along the intersections. The second application included an evaluation of the safety effectiveness of improving the signal head visibility at two signalized intersections located in the City of Edmonton, Alberta, by conducting an automated before-and-after safety analysis using traffic conflicts. The use of automated conflict analysis in before/after safety evaluation can significantly reduce the time needed to reach conclusions about the effectiveness of safety countermeasures. More than 300 video-hours of traffic data were recorded at the two treated intersections before and after applying the treatment. In addition, traffic data was collected at two other intersections with similar characteristics to be used as comparison sites. A before/after road safety evaluation was performed using the Empirical Bayes method that accounts for the effects of the regression to the mean confounding factor. The methodology employs the use of a calibrated conflict-based safety performance function (SPF). The results showed a statistically-significant reduction (24.5%) in the average hourly conflict due to the improved signal heads.Applied Science, Faculty of
Graduate
6
Pumfrey, David John. "The principled design of computer system safety analyses." Thesis, University of York, 1999. http://etheses.whiterose.ac.uk/9797/.
7
Akritidis, Periklis. "Practical memory safety for C." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609600.
8
Faulkner, Alastair. "Data integrity : an often-ignored aspect of safety systems : executive summary." Thesis, University of Warwick, 2004. http://wrap.warwick.ac.uk/1212/.
Abstract:
Data is all-pervasive and is found in all aspects of modern computer systems, and yet many engineers seem reluctant to recognise the importance of data integrity. The conventional view of data, as simply an aspect of software, underestimates the role played by data errors in the behaviour of the system and their potential effect on the integrity of the overall system. In many cases hazard analysis is not applied to data in the same way that it is applied to other system components. Without data integrity requirements, data development and data provision may not attract the degree of rigour that would be required of other system components of a similar integrity. This omission also has implications for safety assessment where the data is often ignored or neglected. This position becomes self reenforcing, as without integrity requirements the importance of data integrity remains hidden. This research provides a wide-ranging overview of the use (and abuse) of data within safety systems, and proposes a range of strategies and techniques to improve the safety of such systems. A literature review and a survey of industrial practice confirmed the conventional view of data, and showed that there is little consistency in the methods used for data development. To tackle these problems this work proposes a novel paradigm, in which data is considered as a separate and distinct system component. This approach not only ensures that data is given the importance that it deserves, but also simplifies the task of providing guidance that is specific to data. Having developed this conceptual framework for data, the work then goes on to develop lifecycle models to assist with data development, and to propose a range of techniques appropriate for the various lifecycle phases. An important aspect of the development of any safety-related system is the production of a safety argument, and this research looks in some detail at the treatment of data, and data development, within this justification. The industrial survey reveals that in data-intensive systems data is often developed quite separately from other elements of the system. It also reveals that data is often produced by an extended data supply chain that may involve a number of disparate organisations. These characteristics of data distinguish it from other system components and greatly complicate the achievement and demonstration of safety. This research proposes methods of modelling complex data supply chains and proposes techniques for tackling the difficult task of safety justification for such systems.
9
Dheedan, Amer Abdaladeem. "Distributed on-line safety monitor based on safety assessment model and multi-agent system." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:6065.
Abstract:
On-line safety monitoring, i.e. the tasks of fault detection and diagnosis, alarm annunciation, and fault controlling, is essential in the operational phase of critical systems. Over the last 30 years, considerable work in this area has resulted in approaches that exploit models of the normal operational behaviour and failure of a system. Typically, these models incorporate on-line knowledge of the monitored system and enable qualitative and quantitative reasoning about the symptoms, causes and possible effects of faults. Recently, monitors that exploit knowledge derived from the application of off-line safety assessment techniques have been proposed. The motivation for that work has been the observation that, in current practice, vast amounts of knowledge derived from off-line safety assessments cease to be useful following the certification and deployment of a system. The concept is potentially very useful. However, the monitors that have been proposed so far are limited in their potential because they are monolithic and centralised, and therefore, have limited applicability in systems that have a distributed nature and incorporate large numbers of components that interact collaboratively in dynamic cooperative structures. On the other hand, recent work on multi-agent systems shows that the distributed reasoning paradigm could cope with the nature of such systems. This thesis proposes a distributed on-line safety monitor which combines the benefits of using knowledge derived from off-line safety assessments with the benefits of the distributed reasoning of the multi-agent system. The monitor consists of a multi-agent system incorporating a number of Belief-Desire-Intention (BDI) agents which operate on a distributed monitoring model that contains reference knowledge derived from off-line safety assessments. Guided by the monitoring model, agents are hierarchically deployed to observe the operational conditions across various levels of the hierarchy of the monitored system and work collaboratively to integrate and deliver safety monitoring tasks. These tasks include detection of parameter deviations, diagnosis of underlying causes, alarm annunciation and application of fault corrective measures. In order to avoid alarm avalanches and latent misleading alarms, the monitor optimises alarm annunciation by suppressing unimportant and false alarms, filtering spurious sensory measurements and incorporating helpful alarm information that is announced at the correct time. The thesis discusses the relevant literature, describes the structure and algorithms of the proposed monitor, and through experiments, it shows the benefits of the monitor which range from increasing the composability, extensibility and flexibility of on-line safety monitoring to ultimately developing an effective and cost-effective monitor. The approach is evaluated in two case studies and in the light of the results the thesis discusses and concludes both limitations and relative merits compared to earlier safety monitoring concepts.
10
Graydon, Iain R. "Comprehension of 500 safety words : a computer-based methodology." Thesis, Aston University, 1986. http://publications.aston.ac.uk/12307/.
11
Roycroft, Steven Michael. "Computer aided method for system safety and reliability assessments." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FRoycroft.pdf.
Abstract:
Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, September 2008.Thesis Advisor(s): Rhoades, Mark M. "September 2008." Description based on title screen as viewed on November 4, 2008.. Includes bibliographical references (p. 75). Also available in print.
12
Al-Qora'n, Lamis Farah. "SAFE-FLOW : a systematic approach for safety analysis of clinical workflows." Thesis, University of Hull, 2015. http://hydra.hull.ac.uk/resources/hull:13064.
Abstract:
The increasing use of technology in delivering clinical services brings substantial benefits to the healthcare industry. At the same time, it introduces potential new complications to clinical workflows that generate new risks and hazards with the potential to affect patients’ safety. These workflows are safety critical and can have a damaging impact on all the involved parties if they fail. Due to the large number of processes included in the delivery of a clinical service, it can be difficult to determine the individuals or the processes that are responsible for adverse events. Using methodological approaches and automated tools to carry out an analysis of the workflow can help in determining the origins of potential adverse events and consequently help in avoiding preventable errors. There is a scarcity of studies addressing this problem; this was a partial motivation for this thesis. The main aim of the research is to demonstrate the potential value of computer science based dependability approaches to healthcare and in particular, the appropriateness and benefits of these dependability approaches to overall clinical workflows. A particular focus is to show that model-based safety analysis techniques can be usefully applied to such areas and then to evaluate this application. This thesis develops the SAFE-FLOW approach for safety analysis of clinical workflows in order to establish the relevance of such application. SAFE-FLOW detailed steps and guidelines for its application are explained. Then, SAFE-FLOW is applied to a case study and is systematically evaluated. The proposed evaluation design provides a generic evaluation strategy that can be used to evaluate the adoption of safety analysis methods in healthcare. It is concluded that safety of clinical workflows can be significantly improved by performing safety analysis on workflow models. The evaluation results show that SAFE-FLOW is feasible and it has the potential to provide various benefits; it provides a mechanism for a systematic identification of both adverse events and safeguards, which is helpful in terms of identifying the causes of possible adverse events before they happen and can assist in the design of workflows to avoid such occurrences. The clear definition of the workflow including its processes and tasks provides a valuable opportunity for formulation of safety improvement strategies.
13
Evans, David Elliot 1971. "Policy-directed code safety." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86424.
14
Roethke, Ed. "Integrating computer-based safety training in a risk control center." Online version, 1998. http://www.uwstout.edu/lib/thesis/1998/1998roethkee.pdf.
15
Wang, Alexander Ning-Yuan. "Air safety--the last decade." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42727.
Abstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (leaf 42).
by Alexander Ning-Yuan Wang.
M.Eng.
16
Twyman, Andrew R. (Andrew Robert) 1977. "Flexible code safety for Win32." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80132.
Abstract:
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 90-93).
by Andrew R. Twyman.
S.B.and M.Eng.
17
Higgins, Mary Katherine. "Airline safety : a comparative analysis." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14941.
Abstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1987.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 59-60.
by Mary Katherine Higgins.
M.S.
18
Gaissmaier, Miriam. "Better Safe than Sorry : Boosting Workplace Safety with Interactive Textiles." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-257492.
Abstract:
Despite various safety regulations and procedures, work accidents remain a significant problem in the global process industry as well as the Swedish steel industry. In order to address personal safety and safety culture, wearable alert systems based on Internet of Things (IoT) technology were prototyped and tested with steel workers in iterative workshops following the Constructive Design Research approach. Results show that interactive textile patches worn on the protection gear are a simple way of transmitting personal alerts with light. Another crucial design factor is to enable the communication between the worker, peers and the control room. The visual design can positively impact the acceptance of the patch, but only adds minimal value to the safety culture. The present study contributes to the field research by approaching work place safety and culture with new, innovative IoT and e-textile technologies.Trots olika säkerhetsbestämmelser och förfaranden förmlir arbetsolyckor ett betydande problem i den globala processindustrin såväl som den svenska stålindustrin. För att ta itu med personlig säkerhet och säkerhetskultur, ett bärbart varningssystem baserade på Internet of Things (IoT)-teknologi prototyperades och testades med stålarbetare i iterativa workshops enligt Constructive Design Research-metoden. Resultat visar att interaktiva textillappar som bärs på skyddsutrustningen är ett enkelt sätt att överföra personliga varningar med ljus. En annan viktig designfaktor är att möjliggöra kommunikation mellan arbetaren, kollegor och kontrollrummet. Den visuella designen kan påverka acceptansen av patchen positivt, men lägger bara till minimalt värde för säkerhetskulturen. Den föreliggande studien bidrar till fältforskningen genom att närma sig arbetsplatsens säkerhet och kultur med nya, innovativa teknologier för IoToch e-textilier.
19
Autey, Jarvis. "Before and after traffic safety evaluations using computer vision techniques." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43598.
Abstract:
Traditionally, road safety analysis has been undertaken using historical collision records. This approach to road safety analysis is reactive in that the analyst has to wait for collisions to take place before an action can be taken. An alternative approach is to study traffic conflicts or near misses which occur more frequently, can be clearly observed and are related to collisions. However, there are issues of subjectivity, reliability, and cost associated with the use of human observers. The use of computer vision techniques to automate the process of collecting traffic conflicts data can help mitigate these problems. This thesis presents the results of a before-after safety evaluation of a proposed design for channelized right-turn lanes. The evaluation uses an automated safety analysis approach to identify and measure the severity of traffic conflicts. The new design, termed “Smart Channels”, decreases the angle of the channelized right turn to approximately 70 degrees, and is considered to have safety benefits for both vehicle-pedestrian and vehicle-vehicle interaction. Data for three treatment sites and one control site, located in British Columbia, Canada, are evaluated using automated traffic conflict analysis that relies on computer vision for conflict detection. The results of the evaluation show that the implementation of the right-turn treatment has resulted in a considerable reduction in the severity and frequency of merging, rear-end, and total conflicts. The total average hourly conflict was reduced by a statistically significant 51 percent, while the average conflict severity was reduced by a statistically significant 41 percent. Many different traffic conflict indicators have been proposed and studied, but the methods of combining the results has not been well examined. This thesis considers four conflict indicators and examines methods of combining or aggregating the information provided by each indicator in order to better account for all components of risk in traffic conflicts. The four indicators are time-to-collision, gap-time, deceleration-to-safety time, and post-encroachment time. Two primary aggregation methods are studied: time aggregation and road-user aggregation. Time aggregation is appropriate for determining aggregate severity over periods of time, and road-user aggregation is used for normalizing risk to the volume of users.
20
Cho, Gyuchoon. "Real Time Driver Safety System." TopSCHOLAR®, 2009. http://digitalcommons.wku.edu/theses/63.
Abstract:
The technology for driver safety has been developed in many fields such as airbag system, Anti-lock Braking System or ABS, ultrasonic warning system, and others. Recently, some of the automobile companies have introduced a new feature of driver safety systems. This new system is to make the car slower if it finds a driver’s drowsy eyes. For instance, Toyota Motor Corporation announced that it has given its pre-crash safety system the ability to determine whether a driver’s eyes are properly open with an eye monitor. This paper is focusing on finding a driver’s drowsy eyes by using face detection technology.
The human face is a dynamic object and has a high degree of variability; that is why face detection is considered a difficult problem in computer vision. Even with the difficulty of this problem, scientists and computer programmers have developed and improved the face detection technologies. This paper also introduces some algorithms to find faces or eyes and compares algorithm’s characteristics.
Once we find a face in a sequence of images, the matter is to find drowsy eyes in the driver safety system. This system can slow a car or alert the user not to sleep; that is the purpose of the pre-crash safety system. This paper introduces the VeriLook SDK, which is used for finding a driver’s face in the real time driver safety system. With several experiments, this paper also introduces a new way to find drowsy eyes by AOI,Area of Interest. This algorithm improves the speed of finding drowsy eyes and the consumption of memory use without using any object classification methods or matching eye templates. Moreover, this system has a higher accuracy of classification than others.
21
Dolginova, Ekaterina 1977. "Safety verification for automated vehicle maneuvers." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47573.
Abstract:
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 83-85).
by Ekanterina Dolginova.
S.B.and M.Eng.
22
Osvald, Leo. "Lightweight Programming Abstractions for Increased Safety and Performance." Thesis, Purdue University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10808010.
Abstract:
In high-level programming languages, programmers do not need to worry about certain implementation details that compilers or interpreters do behind the scenes. However, this oftentimes results in some loss; in the former case, it is the inability to precisely communicate programmer’s intentions to a compiler that compromises safety, and in the latter case, it is the loss of performance because an interpreter needs to do extra work at runtime. Modern languages tend to address this problem differently, albeit rarely without serious limitations. In this dissertation, we develop lightweight programming abstractions whose implementation is practical in multi-paradigm high-level languages such as Scala and C++. The main idea of this work is exploitation of the type system to guide both the code generation (for performance) and type checking (for safety), so that more efficient specialized code is produced or more compiler errors are raised, respectively. This is done by encoding properties of the data as well as data layout, and employing metaprogramming techniques such as staging and template instantiation. We make five main scientific contributions. First, we formalize second-class values with stack-bounded lifetimes as an extension of simply-typed λ calculus, as well as its generalization to polymorphic type systems such as F<:, and calculi with path-dependent types described in the Dependent Object Types (DOT) family; we further generalize the binary first- vs second-class distinction to an arbitrary type lattice—or, more generally, a privilege lattice—then show that abstract type members naturally enable privilege parametricity. Second, we propose a model of checked exceptions based on second-class values, which unlike monads, do not suffer from well-established shortcomings of requiring users to rewrite their code in monadic style throughout. Third, we develop a memory model with data views, which decouple the presentation/interface of a data structure from its layout/storage, and offer not only performance gains through code specialization but also increased safety due to a finer grained control of references to the underlying storage (similar to ownership type systems). Fourth, we design lexically scoped borrowed references with Rust’s semantics, including no mutable aliasing, but in a flow-insensitive setting using second-class values. Fifth, we empirically show within a realistic subset of Scala (MiniScala) that performance gains enabled by stack in place of heap allocation, which may be significant according to previous studies, can be guaranteed via second-class values; in fact, the usage of the more expensive heap is reduced to O(1) in the majority of the benchmarks ported from Scala Native and the Computer Languages Benchmarks Game. Finally, all of these findings are backed by artifacts: an extension of the Scala language with type-checking rules for second-class values and multiple case studies, data views as a library-based framework in C++/Scala along with an evaluation pipeline involving microbenchmarks, an implementation of Rust-like borrowed references as a Scala library, and a modified MiniScala’s type-checker and memory allocation scheme, as well as accordingly ported and annotated benchmarks.
23
Ranjbaran, Abdolrasoul. "A computer program for the stress analysis of reinforced concrete structures." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240977.
24
Busse, Daniela Karin. "Cognitive error analysis in accident and incident investigation in safety-critical domains." Thesis, University of Glasgow, 2002. http://theses.gla.ac.uk/3954/.
Abstract:
A database of 10 years' worth of medical incident data gathered in an Edinburgh Intensive Care Unit was analyzed using the proposed cognitive error analysis approach. In the second live case study, the error analysis approach was evaluated in the field by applying it to incident reporting data that was collected with a newly implemented incident reporting scheme in a Glasgow Neonatal Intensive Care Unit. The insights gained by analyzing the Edinburgh incident scheme were used to inform the design and implementation of the Glasgow incident scheme as part of the unit's existing safety management. Since both were local incident reporting schemes, it was seen as an important factor for its success to take the local context and conditions into account while situating the cognitive error analysis approach as part of these hospitals' safety management strategies. The evaluation of this incident reporting and analysis framework demonstrated the benefits of a structured, psychological “human error” analysis approach that centres on the human aspect of the incident, without isolating it from its context. It is argued that not only could the understanding of the underlying error mechanisms be improved for individual incidents, but the generation of safety recommendations could be supported, and these could then also be evaluated as to their impact on the human "in the loop". The resulting error analysis models could further be used as basis for comparing competing analyses, and also improve analysis traceability by documenting the analysis process and its resulting safety recommendations. Further work is needed in providing "best practices" for the application of the cognitive analytical framework. Further work is also needed in formalizing a way to situate the cognitive error analysis approach within the investigation of local work system factors in the search for the overall incident and accident causation. This thesis aims at demonstrating the benefits of grounding the analysis of human error as part of incident and accident reporting in a cognitive theoretical framework. This will provide the means and the vocabulary to reason about alternative causal hypotheses while also acting as a tool to document and communicate the psychological analysis of human error and its resulting safety recommendations. This approach is proposed as complementing the analysis of human error data by means of error taxonomies grounded in psychological theory.
25
Parmar, Jayesh C. "A method for computer-aided hazard identification of process plants." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/7279.
26
Parker, David James. "Multi-objective optimisation of safety-critical hierarchical systems." Thesis, University of Hull, 2010. http://hydra.hull.ac.uk/resources/hull:3465.
Abstract:
Achieving high reliability, particularly in safety critical systems, is an important and often mandatory requirement. At the same time costs should be kept as low as possible. Finding an optimum balance between maximising a system's reliability and minimising its cost is a hard combinatorial problem. As the size and complexity of a system increases, so does the scale of the problem faced by the designers. To address these difficulties, meta-heuristics such as Genetic Algorithms and Tabu Search algorithms have been applied in the past for automatically determining the optimal allocation of redundancies in a system as a mechanism for optimising the reliability and cost characteristics of that system. In all cases, simple reliability block diagrams with restrictive assumptions, such as failure independence and limited 2-state failure modes, were used for evaluating the reliability of the candidate designs produced by the various algorithms. This thesis argues that a departure from this restrictive evaluation model is possible by using a new model-based reliability evaluation technique called Hierachically Performed Hazard Origin and Propagation Studies (HiP-HOPS). HiP-HOPS can overcome the limitations imposed by reliability block diagrams by providing automatic analysis of complex engineering models with multiple failure modes. The thesis demonstrates that, used as the fitness evaluating component of a multi-objective Genetic Algorithm, HiP-HOPS can be used to solve the problem of redundancy allocation effectively and with relative efficiency. Furthermore, the ability of HiP-HOPS to model and automatically analyse complex engineering models, with multiple failure modes, allows the Genetic Algorithm to potentially optimise systems using more flexible strategies, not just series-parallel. The results of this thesis show the feasibility of the approach and point to a number of directions for future work to consider.
27
Sharvia, Septavera. "Integrated application of compositional and behavioural safety analysis." Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:4473.
Abstract:
To address challenges arising in the safety assessment of critical engineering systems, research has recently focused on automating the synthesis of predictive models of system failure from design representations. In one approach, known as compositional safety analysis, system failure models such as fault trees and Failure Modes and Effects Analyses (FMEAs) are constructed from component failure models using a process of composition. Another approach has looked into automating system safety analysis via application of formal verification techniques such as model checking on behavioural models of the system represented as state automata. So far, compositional safety analysis and formal verification have been developed separately and seen as two competing paradigms to the problem of model-based safety analysis. This thesis shows that it is possible to move forward the terms of this debate and use the two paradigms synergistically in the context of an advanced safety assessment process. The thesis develops a systematic approach in which compositional safety analysis provides the basis for the systematic construction and refinement of state-automata that record the transition of a system from normal to degraded and failed states. These state automata can be further enhanced and then be model-checked to verify the satisfaction of safety properties. Note that the development of such models in current practice is ad hoc and relies only on expert knowledge, but it being rationalised and systematised in the proposed approach – a key contribution of this thesis. Overall the approach combines the advantages of compositional safety analysis such as simplicity, efficiency and scalability, with the benefits of formal verification such as the ability for automated verification of safety requirements on dynamic models of the system, and leads to an improved model-based safety analysis process. In the context of this process, a novel generic mechanism is also proposed for modelling the detectability of errors which typically arise as a result of component faults and then propagate through the architecture. This mechanism is used to derive analyses that can aid decisions on appropriate detection and recovery mechanisms in the system model. The thesis starts with an investigation of the potential for useful integration of compositional and formal safety analysis techniques. The approach is then developed in detail and guidelines for analysis and refinement of system models are given. Finally, the process is evaluated in three cases studies that were iteratively performed on increasingly refined and improved models of aircraft and automotive braking and cruise control systems. In the light of the results of these studies, the thesis concludes that integration of compositional and formal safety analysis techniques is feasible and potentially useful in the design of safety critical systems.
28
Isafiade, Omowunmi Elizabeth. "Ubiquitous intelligence for smart cities: a public safety approach." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25319.
Abstract:
Citizen-centered safety enhancement is an integral component of public safety and a top priority for decision makers in a smart city development. However, public safety agencies are constantly faced with the challenge of deterring crime. While most smart city initiatives have placed emphasis on the use of modern technology for fighting crime, this may not be sufficient to achieve a sustainable safe and smart city in a resource constrained environment, such as in Africa. In particular, crime series which is a set of crimes considered to have been committed by the same offender is currently less explored in developing nations and has great potential in helping to fight against crime and promoting safety in smart cities. This research focuses on detecting the situation of crime through data mining approaches that can be used to promote citizens' safety, and assist security agencies in knowledge-driven decision support, such as crime series identification. While much research has been conducted on crime hotspots, not enough has been done in the area of identifying crime series. This thesis presents a novel crime clustering model, CriClust, for crime series pattern (CSP) detection and mapping to derive useful knowledge from a crime dataset, drawing on sound scientific and mathematical principles, as well as assumptions from theories of environmental criminology. The analysis is augmented using a dual-threshold model, and pattern prevalence information is encoded in similarity graphs. Clusters are identified by finding highly-connected subgraphs using adaptive graph size and Monte-Carlo heuristics in the Karger-Stein mincut algorithm. We introduce two new interest measures: (i) Proportion Difference Evaluation (PDE), which reveals the propagation effect of a series and dominant series; and (ii) Pattern Space Enumeration (PSE), which reveals underlying strong correlations and defining features for a series. Our findings on experimental quasi-real data set, generated based on expert knowledge recommendation, reveal that identifying CSP and statistically interpretable patterns could contribute significantly to strengthening public safety service delivery in a smart city development. Evaluation was conducted to investigate: (i) the reliability of the model in identifying all inherent series in a crime dataset; (ii) the scalability of the model with varying crime records volume; and (iii) unique features of the model compared to competing baseline algorithms and related research. It was found that Monte Carlo technique and adaptive graph size mechanism for crime similarity clustering yield substantial improvement. The study also found that proportion estimation (PDE) and PSE of series clusters can provide valuable insight into crime deterrence strategies. Furthermore, visual enhancement of clusters using graphical approaches to organising information and presenting a unified viable view promotes a prompt identification of important areas demanding attention. Our model particularly attempts to preserve desirable and robust statistical properties. This research presents considerable empirical evidence that the proposed crime cluster (CriClust) model is promising and can assist in deriving useful crime pattern knowledge, contributing knowledge services for public safety authorities and intelligence gathering organisations in developing nations, thereby promoting a sustainable "safe and smart" city.
29
Marriott, Derek Garron. "Analysis of safety-critical parallel software systems." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388710.
30
Liebenwein, Lucas. "Contract-based safety verification for autonomous driving." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120366.
Abstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 77-83).
The safe, successful deployment of autonomous systems under real-world conditions, in part, hinges upon providing rigorous performance and safety guarantees. This thesis considers the problem of establishing and verifying the safety of autonomous systems. To this end, we present a novel framework for the synthesis of safety constraints for autonomous systems, so-called safety contracts, that can be applied to and used by a wide set of real-world systems by acting as a design requirement for the controller implementation of the system. The contracts consider a large variety of road models, guarantee that the controlled system will remain safe with respect to probabilistic models of traffic behavior, and ensure that it will follow the rules of the road. We generate contracts using reachability analysis in a reach-avoid problem under consideration of dynamic obstacles, i.e., other traffic participants. Contracts are then derived directly from the reachable sets. By decomposing large road networks into local road geometries and defining assume-guarantee contracts between local geometries, we enable computational tractability over large spatial domains. To efficiently account for the behavior of other traffic participants, we iteratively alternate between falsification to generate new traffic scenarios that violate the safety contract and reachable set computation to update the safety contract. These counterexamples to collision-free behavior are found by solving a gradient-based trajectory optimization problem. We demonstrate the practical effectiveness of the proposed methods in a set of experiments involving the Manhattan road network as well as interacting multi-car traffic scenarios.
by Lucas Liebenwein.
S.M.
31
Gil, Ronald M. Eng Massachusetts Institute of Technology. "The undefined quest for full memory safety." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119551.
Abstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 59-64).
In this thesis, we explore full memory safety and the various intricacies involved. We analyze existing memory safety techniques in both hardware and software and their many different goals. This task involves determining the limits of the protections guaranteed by these different protection systems, regardless of whether they were explicitly or implicitly stated. It is demonstrated that the common software technique of protecting only allocation bounds does not provide nearly enough of a barrier for attackers. Then, we go beyond particular schemes and examine the limitations of languages, C in particular. We discover many corner cases and ambiguities that prevent even the best possible protection system from providing full memory safety in the context of the C language specification. We also collect some results for the prevalence of these issues, present approaches to further analyze them, and consider how they might extend into other languages or systems.
by Ronald Gil.
M. Eng.
32
Livadas, Carolos. "Formal verification of safety-critical hybrid systems." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42817.
Abstract:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (p. 181-185).
This thesis investigates how the formal modeling and verification techniques of computer science can be used for the analysis of hybrid systems [7,14,22,37] - systems involving both discrete and continuous behavior. The motivation behind such research lies in the inherent similarity of the hierarchical and decentralized control strategies of hybrid systems and the communication and operation protocols used for distributed systems in computer science. As a case study, the thesis focuses on the development of techniques that use hybrid I/O automata [29,30] to model and analyze automated vehicle transportation systems and, in particular, their various protection subsystems - control systems that are used to ensure that the physical plant at hand does not violate its various safety requirements. The thesis is split into two major parts. In the first part, we develop an abstract model of a physical plant and its various protection subsystems - also referred to as protectors. The specialization of this abstract model results in the specification of a particular automated transportation system. Moreover, the proof of correctness of the abstract model leads to simple correctness proofs of the protector implementations for particular specializations of the abstract model. In this framework, the composition of independent protectors is straightforward - their composition guarantees the conjunction of the safety properties guaranteed by the individual protectors. In fact, it is shown that under certain conditions composition holds for dependent protectors also. In the second part, we specialize the aforementioned abstract model to simplified versions of the personal rapid transit system (PRT 200TM) under development at Raytheon Corporation. We examine overspeed and collision protection for a set of vehicles traveling on straight tracks, on binary merges, and on a directed graph of tracks involving binary merges and diverges. In each case, the protectors sample the state of the physical plant and take protective actions to guarantee that the physical plant does not reach hazardous states. The proofs of correctness of such protectors involve specializing the abstract protector to the physical plant at hand and proving that the suggested protector implementations are correct. This is done by defining simulations among the states of the protector implementations and their abstract counterparts.
by Carolos Livadas.
M.Eng.
33
Azevedo, Luís Pedro da Silva. "Scalable allocation of safety integrity levels in automotive systems." Thesis, University of Hull, 2015. http://hydra.hull.ac.uk/resources/hull:13618.
Abstract:
The allocation of safety integrity requirements is an important problem in modern safety engineering. It is necessary to find an allocation that meets system level safety integrity targets and that is simultaneously cost-effective. As safety-critical systems grow in size and complexity, the problem becomes too difficult to be solved in the context of a manual process. Although this thesis addresses the generic problem of safety integrity requirements allocation, the automotive industry is taken as an application example. Recently, the problem has been partially addressed with the use of model-based safety analysis techniques and exact optimisation methods. However, usually, allocation cost impacts are either not directly taken into account or simple, linear cost models are considered; furthermore, given the combinatorial nature of the problem, applicability of the exact techniques to large problems is not a given. This thesis argues that it is possible to effectively and relatively efficiently solve the allocation problem using a mixture of model-based safety analysis and metaheuristic optimisation techniques. Since suitable model-based safety analysis techniques were already known at the start of this project (e.g. HiP-HOPS), the research focuses on the optimisation task. The thesis reviews the process of safety integrity requirements allocation and presents relevant related work. Then, the state-of-the-art of metaheuristic optimisation is analysed and a series of techniques, based on Genetic Algorithms, the Particle Swarm Optimiser and Tabu Search are developed. These techniques are applied to a set of problems based on complex engineering systems considering the use of different cost functions. The most promising method is selected for investigation of performance improvements and usability enhancements. Overall, the results show the feasibility of the approach and suggest good scalability whilst also pointing towards areas for improvement.
34
Pampin-Garcia, R. "Fusion power : safety and environmental analysis using integrated, three-dimensional computer modelling." Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542395.
Abstract:
Fusion power studies provide insight into physics and technology issues that need addressing to develop fusion as an optimal electricity generation alternative in the near future. As part of them, calculations are performed of different parameters important for the safety and environmental assessments of power plant concepts based on magnetically confined burning plasmas. These assessments help optimise such concepts, and involve many different physics disciplines and the use of large computational codes and nuclear databases. The work presented in this thesis has been developed within the Fusion Technology group of the UKAEA Fusion Division, under the framework of the European Power Plant Conceptual Study. For the safety and environmental assessment of four different fusion power plant concepts, estimations were made of the amount, characteristics and radiotoxicity of the activated material arising from neutron irradiation of the structures. Results were used to analyse: (a) public safety, through the bounding accident analysis, obtaining maximum temperature excursions following hypothetical, internally-driven, worst-case accidents, and (b) the radioactive waste arising from the operation of the plant, and in particular the possibility to re-utilise some of the irradiated material. Calculations were assisted by, and helped in the development of, a new computational tool coupling the neutron transport, activation and thermal analyses to the same three-dimensional geometry
35
Creely, Karen Sarah. "Communication of hazard and risk information using computer multimedia safety data sheets." Thesis, University of Aberdeen, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440055.
Abstract:
Two mmSDSs were developed, the first for two, similar, formaldehyde-based embalming fluids, the second for a solvent-based paint. Workplace and laboratory intervention studies were undertaken to evaluate the effectiveness of the mmSDSs in increasing knowledge of the products hazards and risks; inducing attitudinal and risk perception changes; appropriate protective behaviour and decreasing inhalation exposure. Subjects received either the mmSDS or the conventional SDS package, with subjects being assessed both pre- and several times post-intervention. Fourteen embalmers participated in the workplace evaluation. Knowledge increased, with more mmSDS users showing increases at the first post-intervention study. Cumulative exposure to formaldehyde decreased slightly post-intervention, although there were no significant differences between packages. There was little change in the use of protective measures due to embalmers already using measures available. Twenty-four members of the general public participated in a laboratory-based painting study. None had previously used the paint and knowledge increased for both mmSDS and SDS users. The mmSDS was more effective at promoting positive changes in the wearing of masks, hand washing and ventilation. Cumulative exposures to solvents decreased, although there were no statistically significant differences between packages. The impact of the mmSDSs and SDSs interventions on participants’ behaviour and exposure to chemicals was more pronounced in the laboratory study however the majority of the workplace participants were already using all the protective measures available. Overall, the findings suggest that the mmSDS concept may be an effective method of providing chemical hazard and risk information in the workplace.
36
Moore, Albert W. "A computer-based training course for assessing material safety data sheet comprehension." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06232009-063332/.
37
Fernandes, Dias Claudio. "Driver’s Safety Analyzer: Sobriety, Drowsiness, Tiredness, and Focus." Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1587477829716502.
38
Ozdemir, Kadir. "Verifying the safety properties of concurrent systems via simultaneous reachability." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/10294.
Abstract:
This thesis proposes two techniques, simultaneous reachability analysis and simultaneous product method, to reduce the number of global states to be analyzed for verifying the safety properties of concurrent systems. Both techniques utilize the idea of simultaneous execution of transitions. Simultaneous reachability analysis is proposed for verifying a specific set of safety properties asserting absence of logical errors of communication protocols specified as a network of n ($n\ge 2$) processes communicating over error-free, bounded, FIFO queues, without placing any restrictions on the topology of the network and process structures. We prove that simultaneous reachability analysis not only verifies the absence of logical errors such as deadlock, nonexecutable transition, unspecified reception and buffer overflow (in a correct protocol) but also identifies every deadlock state, every nonexecutable transition, every missing receiving transition causing unspecified receptions and every channel at which a buffer overflow occurs (in an incorrect protocol). An empirical study is carried out to demonstrate the efficiency of simultaneous reachability analysis in terms of time and memory requirements. In this study, 300 protocols constructed by an automatic empirical protocol synthesizer are used and results are evaluated with respect to the characteristics of these protocols. Empirical results show that using simultaneous reachability analysis substantially reduces the number of global states. Simultaneous product method is proposed for verifying general safety properties of finite-state concurrent programs. In this method, a concurrent program is specified as a collection of processes represented by finite automata on finite words and the concurrent behavior of these processes is defined by usual operational semantics (CSP-style): actions that appear in several processes are synchronized, others are interleaved. Verification problem is formulated in the framework of automata-theoretic model-checking where the negation of a safety property is convened to a finite automaton on finite words and then an automaton is obtained by taking the simultaneous product of the automata representing processes and the automaton representing the negation of a safety property. We prove that any safety property for a finite-state concurrent program can be efficiently verified by using simultaneous product method.
39
Basir, Nurlida. "Safety cases for the formal verification of automatically generated code." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/160073/.
Abstract:
Model-based development and automated code generation are increasingly used for actual production code, in particular in mathematical and engineering domains. However, since code generators are typically not qualified, there is no guarantee that their out- put is correct or even safe. Formal methods which are based on mathematically-based techniques have been proposed as a means to improve software quality by providing formal safety proofs as explicit evidence for the assurance claims. However, the proofs are often complex and may also be based on assumptions and reasoning principles that are not justified. This causes concerns about the trustworthiness of the proofs and hence the assurance claims on the safety of the program. This thesis presents an approach to systematically and automatically construct comprehensive safety cases using the Goal Structuring Notation from a formal analysis of automatically generated code, based on automated theorem proving, and driven by a set of safety requirements and properties. We also present an approach to systematically derive safety cases that argue along the hierarchical structure of systems in model-based development. This core safety case is extended by separately specified auxiliary information from other verification and validation activities such as testing. The thesis also presents an approach to develop safety cases that correspond to the formal proofs found by automated theorem provers and that reveal the underlying proof argumentation structure and top-level assumptions. The resulting safety cases will make explicit the formal and informal reasoning principles, and reveal the top-level assumptions and external dependencies that must be taken into account in demonstrating software safety. The safety cases can be thought as \structured reading guide" for the software and the safety proofs that provide trace- able arguments on the assurance provided. The approach has been illustrated on code generated using Real-Time Workshop for Guidance, Navigation, and Control (GN&C) systems of NASA' s Project Constellation and on code for deep space attitude estimation generated by the AutoFilter system developed at NASA Ames.
40
Davis, Eli Bristol. "Fast, compatible, complete memory safety For C programs." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/112860.
Abstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 95-97).
The lack of memory safety in C/C++ programs is one of, if not the, most persistent and costly sources of program exploits. Attacks based on memory corruption can range from the reading of private data to a complete hostile takeover of a process. While many solutions to this problem have been proposed, it is as of yet unsolved-as old memory corruption attacks are rendered obsolete, new attacks continually spring up. This lack of success is largely due to the trade-offs that memory safety solutions make between completeness, compatibility, and overhead. There no a single solution with all three properties, and a solution must have all three in order to once-and-for-all solve the lack of memory safety in C programs: If a solution is incomplete, attackers will find a workaround. Unless it is backwards compatible and low-overhead, it will not be deployed in production. My goal for this thesis was to take an existing system which is close to having all three properties, and add the missing property. I chose to work with SoftboundCETS an LLVM pass which is already complete and backwards compatible, but has high runtime overhead. In this thesis, I take SoftboundCETS and heavily optimize its runtimes, reducing its total overhead by half. I split the original pass into two separate passes (one to mark which instructions were to be instrumented and the second to do the actual instrumentation) and then insert several optimization passes between them. I test my results on selected benchmarks from SPEC2000 and SPEC2006, and create a virtual machine image which allows my results to be reliably reproduced. Lastly, I propose a number of further optimizations which would allow Softbound-CETS to achieve low enough overhead to be used in a mid-performance production system.
by Eli Bristol Davis.
M. Eng.
41
Janiuk, Ludvig, and Johan Sjölén. "Probabilistic Least-violating Control Strategy Synthesis with Safety Rules." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229867.
Abstract:
We consider the problem of automatic control strategy synthesis for discrete models of robotic systems, where the goal is to travel from some region to another while obeying a given set of safety rules in an environment with uncertain properties. This is a probabilistic extension of the work by Jana Tumová et al. that is able to handle uncertainty by modifying the least-violating strategy synthesis algorithm. The first novel contribution is a way of modelling uncertain events in a map as a Markov decision process with a specific structure, using what we call "Ghost States". We then introduce a way of constructing a Product Automaton analogous to the original work, on which a modified probabilistic version of Dijkstra's algorithm can be run to synthesize the least-violating plan. The result is a synthesis algorithm that works similarly to the original, but can handle probabilistic uncertainty. It could be used in cases where e.g. uncertain weather conditions or the behaviour of external actors can be modelled as stochastic variables.Vi undersöker automatisk kontrollstrategisyntes (automatic control strategy synthesis) av diskreta robotsystem där målet för roboten är att färdas från en region till en annan medan den följer en mängd säkerhetsregler i en miljö med probabilistiskt osäkra egenskaper. Detta är en uppföljning av arbete gjort av Jana Tumová et al. Vi utvidgar deras arbete genom att modifiera strategisyntesalgoritmen så att den kan hantera probabilistiska situationer. Vårt första bidrag är ett sätt att modellera probabilistiska situationer i en karta genom en så kallad "markov decision process" med en specifik struktur som vi kallar för "Ghost States" (spöktillstånd). Vi bidrar även med ett sätt att konstruera en produktautomat som är analog till originalarbetets produktautomat. På vår produktautomat kan en probabilistisk variant av Dijkstras algoritm köras för att framställa en plan som är "least-violating" (bryter mot säkerhetsreglerna minst). Resultatet är en syntesalgorithm som fungerar som originalet men som även kan hantera stokastiska osäkerheter. Syntesalgoritmen skulle till exempel kunna användas i de fall där ovissa väderlekar eller beteendet av externa aktörer kan modelleras som stokastiska variabler.
42
Wu, James 1975. "A comparison of programming languages for real-time, safety-critical programming /." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30772.
Abstract:
As the number of applications of computers controlling safety-critical operations increases, the need to ensure the safety and reliability of the software that controls those computers increases proportionally. Ultimately, such software properties are the result of appropriate design and implementation. However, certain characteristics of the language in which the software is written can have an impact on how that language facilitates both design and implementation, and how it encourages safety and reliability in the resulting software.This paper explores the language characteristics that can impact the safety and reliability of the software produced. The goal is to provide a set of criteria that can be used for the selection of an appropriate language for real-time, safety-critical development. It proposes a set of characteristics that can affect the suitability of a language to such development, and compares a selection of common programming languages, including Ada, C, C++ and Java, against this framework.
43
Georgakopoulos, Vassilis. "Food safety training : a model HACCP instructional technique." Thesis, Manchester Metropolitan University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340452.
44
Gill, Janet A. "Safety analysis of heterogeneous-multiprocessor control system software." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA231859.
Abstract:
Thesis (M.S. in Computer Science)--Naval Postgraduate School, December 1990.Thesis Advisor(s): Shimeall, Timothy J. Second Reader: Hefner, Kim A. S. "December 1990." Description based on title screen as viewed on March 31, 2010. DTIC Identifier(s): Computer Program Reliability, System Safety. Author(s) subject terms: Software Safety, Petri Net, Fault Tree, Software Engineering, Integrated System Analysis. Includes bibliographical references (p. 47-51). Also available in print.
45
Seotsanyana, Motlatsi. "Formal specification and verification of safety interlock systems : a comparative case study /." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/710.
46
Sajjad, Imran. "Autonomous Highway Systems Safety and Security." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5696.
Abstract:
Automated vehicles are getting closer each day to large-scale deployment. It is expected that self-driving cars will be able to alleviate traffic congestion by safely operating at distances closer than human drivers are capable of and will overall improve traffic throughput. In these conditions, passenger safety and security is of utmost importance.
When multiple autonomous cars follow each other on a highway, they will form what is known as a cyber-physical system. In a general setting, there are tools to assess the level of influence a possible attacker can have on such a system, which then describes the level of safety and security. An attacker might attempt to counter the benefits of automation by causing collisions and/or decreasing highway throughput.
These strings (platoons) of automated vehicles will rely on control algorithms to maintain required distances from other cars and objects around them. The vehicle dynamics themselves and the controllers used will form the cyber-physical system and its response to an attacker can be assessed in the context of multiple interacting vehicles.
While the vehicle dynamics play a pivotal role in the security of this system, the choice of controller can also be leveraged to enhance the safety of such a system. After knowledge of some attacker capabilities, adversarial-aware controllers can be designed to react to the presence of an attacker, adding an extra level of security.
This work will attempt to address these issues in vehicular platooning. Firstly, a general analysis concerning the capabilities of possible attacks in terms of control system theory will be presented. Secondly, mitigation strategies to some of these attacks will be discussed. Finally, the results of an experimental validation of these mitigation strategies and their implications will be shown.
47
Pajjuri, Srinivas Reddy. "Computer model to simulate truck accidents on exit ramps." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08182009-040509/.
48
Pratt, Norman Derek. "Pragmatic application of formal methods to safety critical systems." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/843228/.
Abstract:
Formal Methods started primarily as a software development method, but now embrace a wide spectrum of purposes and techniques. This report considers one possible application of Formal Methods to Safety Critical Systems, namely its use in validation of a mechanism for a safety critical system. The technique involves construction of a Formal Model covering the mechanism, the real world aspects of interest, and the safety requirement. The technique supports exploring the behaviour of mechanisms in a mathematical way, and in particular establishing whether the behaviour complies with a safety property. The technique enables the analysis of mechanisms with complex behaviour, such as software based mechanisms, to be treated with a confidence not achievable with informal techniques such as Fault Tree Analysis. Proof has the power to show the absence of errors, and this is quite unlike the basis of other safety analysis techniques. It is this potential of proof which enables Formal Modelling to deal succinctly with the enormous numbers of cases typical of software mechanisms. The critical issue with Formal Modelling is Validity, ensuring the conclusions generated are valid in the real world. The approach adopted is based on the standard mathematical modelling method employed by Applied Mathematics. A variety of typical Formal Methods techniques are then integrated into this method to customise it. This integration is shown to be readily achieved, and results in a powerful Formal Modelling method. Certain pragmatic difficulties are identified. Chief amongst these is the considerable skill and experience needed to master the mathematical basis of the method. Overall, the conclusion is that Formal Modelling is a new analysis technique that is both complementary and supplementary to existing Safety Analysis techniques.
49
Kamolpornwijit, Witchakorn. "P-TAXI : enforcing memory safety with programmable tagged architecture." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105996.
Abstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 104-112).
Buffer overflow is a well-known problem that remains a threat to software security. With the advancement of code-reuse attacks and return-oriented programming (ROP), it becomes problematic to protect a program from being compromised. Several defenses have been developed in an attempt to defeat code-reuse attacks. However, there is still no solution that provides complete protection with low overhead. In this thesis, we improved TAXI, a ROP defense technique that utilizes a tagged architecture to prevent memory violations. Inspired by Programmable Unit for Metadata Processing (PUMP), we modified TAXI so that enforcement policies can be programmed by user-level code and called it P-TAXI (Programmable TAXI). We demonstrated that, by using P-TAXI, we were able to enforce memory safety policies, including return address protection, stack garbage collection, and memory compartmentalization. In addition, we showed that P-TAXI can be used for debugging and taint tracking.
by Witchakorn Kamolpornwijit.
M. Eng.
50
Trafford, Paul Joseph. "The use of formal methods for safety-critical systems." Thesis, Kingston University, 1997. http://eprints.kingston.ac.uk/20609/.
Abstract:
An investigation is presented into the use of formal methods for the production of safety-critical systems with embedded software. New theory and procedures are tested on an industrial case study, the formal specification and refinement of a communications protocol for medical devices (the Universal Flexport protocol [copyright]). On reviewing the current literature, a strong case emerges for grounding any work within an overall perspective that integrates the experience of safety engineering and the correctness of formal methods. Such a basis, it is argued, is necessary for an effective contribution to the delivery with assurance of life-critical software components. Hence, a safety-oriented framework is proposed which facilitates a natural flow from safety analysis of the entire system through to formal requirements, design, verification and validation for a software model undergoing refinement towards implementation. This framework takes a standard safety lifecycle model and considers where and how formal methods can play apart, resulting in procedures which emphasise the activities most amenable to formal input. Next, details of the framework are instantiated, based upon the provision of a common formal semantics to represent both the safety analysis and software models. A procedure, FTBuild, is provided for deriving formal requirements as part of the process of generating formalised fault trees. Work is then presented on establishing relations between formalised fault trees and models, extending results of other authors. Also given are some notions of (property) conformance with respect to the given requirements. The formal approach itself is supported by the enhancement of the theory of con-formance testing that has been developed for communication systems. The basis of this work is the detailed integration of already established theories: a testing system for process algebra (the Experimental System due to Hennessy and de Nicola) and a more general observation framework (developed by the LOTOSphere consortium). Notions of conformance and robustness are then examined in the context of refinement for the process algebra, (Basic) LOTOS, resulting in the adoption of the commonly accepted 'reduction' relation for which a proof is given that it is testable. Then a new algorithm is developed for a single (canonical) tester for reduction, which is unified in that it tests simultaneously for both con-formance and robustness. It also allows, in certain cases, a straightforward implementation as a Full LOTOS process with the ability to give some diagnostics in the case of failure. The text is supported by examples and some guidelines for use. Finally, having established these foundations, the methodology is demonstrated on the Flexport protocol through two iterations of FTBuild which demonstrate how the activities of specification, safety analysis, validation and refinement are all brought together.