Software System Safety

Leveson, Nancy G.; Weiss, Kathryn Anne

doi:10.1016/b978-0-7506-8580-1.00015-4

Cited by 18 publications

(18 citation statements)

References 6 publications

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“…Senge, 2006), self-organising (Rasmussen, 1997), and continuous adaptation are the central tenet of HRO. The key to improvement of safety in HROs is to decouple reliability from safety, the former indicates to what extent an individual player in the system follows the specified procedure whereas the latter is a property of the system as a whole (Leveson, 1995(Leveson, , 2011. Safety performance is thus to be achieved through integration of the otherwise conflicting goals of production and safety, or of the sometimes conflicting safety goals in tackling different hazard sources, through careful devises of safety constraints at different levels of the hierarchal control structure of the system (Leveson, 2011).…”

Section: Implications For Accident Preventionmentioning

confidence: 99%

Management of climatic heat stress risk in construction: A review of practices, methodologies, and future research

Rowlinson

YunyanJia

et al. 2014

Accident Analysis & Prevention

129

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Climatic heat stress leads to accidents on construction sites brought about by a range of human factors emanating from heat induced illness, and fatigue leading to impaired capability, physical and mental. It is an occupational characteristic of construction work in many climates and the authors take the approach of re-engineering the whole safety management system rather than focusing on incremental improvement, which is current management practice in the construction industry. From a scientific viewpoint, climatic heat stress is determined by six key factors: (1) air temperature, (2) humidity, (3) radiant heat, and (4) wind speed indicating the environment, (5) metabolic heat generated by physical activities, and (6) "clothing effect" that moderates the heat exchange between the body and the environment. By making use of existing heat stress indices and heat stress management processes, heat stress risk on construction sites can be managed in three ways: (1) control of environmental heat stress exposure through use of an action-triggering threshold system, (2) control of continuous work time (CWT, referred by maximum allowable exposure duration) with mandatory work-rest regimens, and (3) enabling self-paced working through empowerment of employees. Existing heat stress practices and methodologies are critically reviewed and the authors propose a three-level methodology for an action-triggering, localized, simplified threshold system to facilitate effective decisions by frontline supervisors. The authors point out the need for "regional based" heat stress management practices that reflect unique climatic conditions, working practices and acclimatization propensity by local workers indifferent geographic regions. The authors set out the case for regional, rather than international, standards that account for this uniqueness and which are derived from site-based rather than laboratory-based research.

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Section: Implications For Accident Preventionmentioning

confidence: 99%

Management of climatic heat stress risk in construction: A review of practices, methodologies, and future research

Rowlinson

YunyanJia

et al. 2014

Accident Analysis & Prevention

129

View full text Add to dashboard Cite

show abstract

“…The DOS histogram sheds light on the fundamental nature of the feasible solution set and difficulty of solving the optimization problem. Such problems frequently arise when constructing complex systems for aerospace and defense applications (Leveson and Weiss 2009). The lack of methodical approaches that enable the comparison of competing safety-critical system requirements, while optimizing performance, stymie the development of next-generation complex systems.…”

Section: Introductionmentioning

confidence: 99%

Estimating the Density of States of Boolean Satisfiability Problems on Classical and Quantum Computing Platforms

Sahai

Mishra

Pasini

et al. 2020

AAAI

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Given a Boolean formula ϕ(x) in conjunctive normal form (CNF), the density of states counts the number of variable assignments that violate exactly e clauses, for all values of e. Thus, the density of states is a histogram of the number of unsatisfied clauses over all possible assignments. This computation generalizes both maximum-satisfiability (MAX-SAT) and model counting problems and not only provides insight into the entire solution space, but also yields a measure for the hardness of the problem instance. Consequently, in real-world scenarios, this problem is typically infeasible even when using state-of-the-art algorithms. While finding an exact answer to this problem is a computationally intensive task, we propose a novel approach for estimating density of states based on the concentration of measure inequalities. The methodology results in a quadratic unconstrained binary optimization (QUBO), which is particularly amenable to quantum annealing-based solutions. We present the overall approach and compare results from the D-Wave quantum annealer against the best-known classical algorithms such as the Hamze-de Freitas-Selby (HFS) algorithm and satisfiability modulo theory (SMT) solvers.

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“…The DOS histogram sheds light on the fundamental nature of the feasible solution set and difficulty of solving the overall optimization problem. As stated earlier, these problems frequently arise when constructing complex systems for aerospace and defense applications (Leveson & Weiss, 2009).…”

Section: Introductionmentioning

confidence: 99%

Estimating the Density of States of Boolean Satisfiability Problems on Classical and Quantum Computing Platforms

Sahai¹,

Mishra²,

Pasini³

et al. 2019

Preprint

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Given a Boolean formula φ(x) in conjunctive normal form (CNF), the density of states counts the number of variable assignments that violate exactly e clauses, for all values of e. Thus, the density of states is a histogram of the number of unsatisfied clauses over all possible assignments. This computation generalizes both maximum-satisfiability (MAX-SAT) and model counting problems and not only provides insight into the entire solution space, but also yields a measure for the hardness of the problem instance. Consequently, in real-world scenarios, this problem is typically infeasible even when using state-of-the-art algorithms. While finding an exact answer to this problem is a computationally intensive task, we propose a novel approach for estimating density of states based on the concentration of measure inequalities. The methodology results in a quadratic unconstrained binary optimization (QUBO), which is particularly amenable to quantum annealing-based solutions. We present the overall approach and compare results from the D-Wave quantum annealer against the best-known classical algorithms such as the Hamze-de Freitas-Selby (HFS) algorithm and satisfiability modulo theory (SMT) solvers.

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Software System Safety

Cited by 18 publications

References 6 publications

Management of climatic heat stress risk in construction: A review of practices, methodologies, and future research

Management of climatic heat stress risk in construction: A review of practices, methodologies, and future research

Estimating the Density of States of Boolean Satisfiability Problems on Classical and Quantum Computing Platforms

Estimating the Density of States of Boolean Satisfiability Problems on Classical and Quantum Computing Platforms

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