System Safety Engineering Research Articles

Special issue section on process system safety and risk engineering

Special issue section on process system safety and risk engineering

Control Effectiveness: Metric Development and Application to Resilient Lunar Habitat Design

System safety engineering in its bare essence involves identifying, assessing, and mitigating, or controlling, hazards. Appropriate safety controls are selected using hazard reduction precedence principles, prior experience, or by assessing their impact on residual risk (together with other factors like cost). We propose a control effectiveness metric as one way to systematically and consistently evaluate potential safety controls individually and thereby facilitate selecting a shortlist of potential controls for subsequent integrated evaluation. The control effectiveness metric considers a safety control’s availability when needed, the probability that its design is adequate in addressing the targeted hazard, the probability that the design will be implemented as intended, and the relationship between the time it takes for the safety control to address its target hazard and the time before the hazard propagates. We demonstrated the use of our metric on a lunar habitat design using a physics-based habitat simulator. High control effectiveness and safety controls result in a habitat with high resilience, while low control effectiveness results in lower resilience.

Advances and novel applications in systems reliability and safety engineering (selected papers of the International Conference of SRSE 2022)

Advances and novel applications in systems reliability and safety engineering (selected papers of the International Conference of SRSE 2022)

Rapid prototyping of FBG-based optical sensors for vibration analysis of mechatronic systems

The detection and study of vibrations play a fundamental role in the monitoring and safety of engineering systems. This is especially true in the aerospace sector, where the operating environment is often hostile, and the constraints on weights and dimensions are very tight. For these reasons, the research and application of sensors based on optical signal transmission are becoming increasingly important. The opportunity to implement distributed measurements along a single optical fiber, the small size and weight, and the high resistance to electromagnetic interference make this technology an ideal candidate for the development of next-generation aerial platforms. In this paper, the authors focus on designing and developing a novel sensor that employs Fiber Bragg Grating (FBG) for vibration detection. Their primary aim is to explore the potential and constraints of this technology and build an initial prototype for testing purposes. Additionally, the project enabled the authors to experiment with rapid prototyping techniques that rely on 3D printing and additive manufacturing. The impact of various design choices, such as materials, geometry, and manufacturing, on the demonstrator sensitivity was explored by analysing the problem mathematically. A Matlab script was developed to estimate dimensions, weights, and dynamic performances, and modelling FEM was used for validation.

Comprehensive risk management of health, safety and environment for social emergency rescue organization

During the rescue and relief work of social emergency rescue organizations, the rescue team members face significant responsibilities and risks. Social rescue organizations need to improve funding, available equipment and other aspects compared with professional emergency rescue organizations. Moreover, the development of rescue levels among emergency rescue organizations is unbalanced, and rescue teams’' comprehensive quality and skills are uneven. To understand the safety risks of these organizations before the implementation of rescue and relief tasks, the task situation and its characteristics must be assessed timely, and safety must be ensured under the premise of efficient completion of the rescue missions. Based on the theory of safety system engineering and health, safety, and environment risk management, a risk management model is established to achieve a closed-loop risk management. The risk factors in rescue and relief tasks of social rescue organizations were identified, and a health, safety and environment risk assessment index system and grading standard were established. A gray cloud model was applied for the evaluation method, the problems of information randomness, risk-level boundary fuzziness and randomness of the evaluation index data were effectively solved. Subsequently, a risk hierarchical early warning and control strategies were proposed to allocate emergency resources rationally. The proposed method was verified and found to have universal applicability and strong practicability.

Discussion on the Application of System Safety Engineering in Coal Mine Capital Construction-well and Lane Engineering Construction

Discussion on the Application of System Safety Engineering in Coal Mine Capital Construction-well and Lane Engineering Construction

A SysML Profile for MIL‐STD‐882E (System Safety)

AbstractThis paper presents a profile that extends the Systems Modeling Language (SysML) to support the requirements of MIL‐STD‐882E and facilitate the System Safety process. MIL‐STD‐882E is the U.S. Department of Defense (DoD) standard for System Safety Engineering (SSE). It mandates a series of analyses for hazard identification and tracking throughout system development, operation, sustainment, and disposal. These analyses are required to be documented in a series of reports set forth in the standard. For large systems, analyzing the system design and producing the mandated reports requires significant effort with a corresponding cost and resource impact on the overall program. Furthermore, while such analyses should be integrated with the development processes, they are often performed after design decisions are made and without the involvement of the primary development team. The System Safety Profile (SSP) presented here integrates the System Safety process with the design process by translating SSE concepts into structured elements within SysML, including representations of System Safety hazards, risks, mitigations, analysis activities, and the relations between them.

Research on Fault Tree Reconstruction Based on Contingency

The fault tree analysis (FTA) method is an important analysis method for safety system engineering. Traditional accident analysis theory agrees that basic events lead to top events, but it does not fully consider that the accident process is accidental, and the calculation results exaggerate the probability of accident occurrence. This paper selects typical collision accidents, analyzes the shortcomings of the existing fault tree, indicates that there is a contingency in the accident process, constructs a probability fault tree based on the traditional fault tree, and puts forward concepts of “probability AND gate” and “probability OR gate”. In addition, based on the traditional quantitative analysis method of fault trees, calculations of the occurrence probability, probability importance coefficient, and critical importance coefficient of top events are modified, and the modified quantitative calculation is applied to accident cases.

A photochromic nylon webbing for ultra-violet light sensing

Webbing structures are essential to the safety of engineering systems that routinely endure excessive sunlight exposure. Particularly damaging is the ultra-violet (UV) component of sunlight that may degrade polymer chains, thereby compromising mechanical strength. Despite considerable progress in structural health monitoring, UV damage sensors for webbing structures are still lacking. To fill this gap, we propose a simple and fast fabrication process for a nylon webbing structure that exhibits photochromic responses to UV irradiation. The photochromic webbing structure is fabricated by coating a nylon strap with a photochromic polymer. The photochromic webbing structure demonstrates high sensitivity to a wide range of UV irradiation energy. In addition, the webbing structure maintains photochromism even after photodegradation due to extreme UV irradiation (equivalent to 72 h of sunlight exposure). Our analysis indicates that a photochromic dye concentration of 1.00% is optimal for UV sensing. The proposed photochromic webbing could facilitate health monitoring of industrial, aeronautical, and aerospace structures.

Bibliometric Analysis and Visualization of Bayesian Network Application in Safety Field

Bayesian network (BNs) has been widely used in uncertain knowledge modeling since it was proposed, especially in safety assessment and risk prediction. In order to fully understand the application status of Bayesian network in the field of safety, 3111 sample documents were collected from the web of science core collection database. Through CiteSpace technology text mining and visual analysis software, document output, keywords, author cooperation, organization cooperation, citation and journal distribution were analyzed. The results show that: FAISAL KHAN, MOHAMED ABDELATY, HELAI HUANG, TAREK SAYED, JAEYOUNG LEE, etc. published Bayesian networks The most widely used literature in the field of safety has made an important contribution to the development of this field; institutional cooperation is mainly based on Univ Central Florida, MEM Univ Newfoundland, Univ British Columbia, Tongji Univ, Texas A & M Univ, cents Univ, Delft Univ technology and other universities; journal distribution of literature is mainly based on the core functions of Bayesian network, and mainly distributed in ACCIDENT ANALYSIS AND PREVENTION, TRANSPORTATION RESEARCH RECODE, RELIABILITY ENGINEERING SYSTEM SAFETY and SAFETY SCIENCE.

Systematic approach to consider HRC in early design phase

The design of Human-Robot-Collaboration (HRC) applications faces many challenges especially in the early design phase. One important issue is the different interests of system designer and safety engineers during the design. The interest conflict leads to high coordination effort and optimization loops to generate a solution, which meets the given process requirements. This paper presents a systematic approach for the system designer to consider safety in the early design phase of HRC applications. The described approach is basis for a future software tool, which supports the system designer to generate first HRC safety concepts. Therefore, the paper presents the general architecture and explains the three main modules of the tool approach: main safety principles definitions, safety capability taxonomy and the usage of look-up tables.

Global dynamics perspective on macro- to nano-mechanics

In about the last two decades, global nonlinear dynamics has been evolving in a revolutionary way, with the development of sophisticated techniques employing concepts/tools of dynamical systems, bifurcation, and chaos theory, and applications to a wide variety of mechanical/structural systems. The relevant achievements entail a substantial change of perspective in dealing with vibration problems and are ready to meaningfully affect the analysis, control, and design of systems at different scales, in multiphysics contexts too. After properly framing the subject within some main stages of developments of nonlinear dynamics in solid/structural mechanics, as occurred over the last 40 years, the article focuses on highlighting the role played by global analysis in unveiling the nonlinear response and actual safety of engineering systems in different environments. Reduced order models of macro-/micro-structures are considered. Global dynamics of a laminated plate with von Karman nonlinearities, shear deformability, and full thermomechanical coupling allows to highlight the meaningful effects entailed by the slow transient thermal dynamics on the fast steady mechanical responses. An atomic force microcantilever is referred to for highlighting the severe worsening of overall stability associated with the application of an external feedback control and the importance of global dynamics for conceiving and effectively implementing a control procedure aimed at enhancing engineering safety. The last part of the article dwells on the general role that a global dynamics perspective is expected to play in the safe design of real systems, in the near future, focusing on how properly exploiting concepts and tools of dynamical integrity to evaluate response robustness in the presence of unavoidable imperfections, and to improve the system’s actual load carrying capacity.

Safety of engineering systems of buildings with limited heat supply

In case of emergencies in large heat supply systems, the water temperature in the supply line of the heat supply system is reduced. It is necessary to determine the acceptable duration of the heat supply system during an emergency, taking into account the thermal accumulation of the external fencing and variable water consumption in the hot water supply system. A study was made of the operating modes of the heat supply system in conditions of emergency heat supply from the CHP. The factors affecting the thermal regime of buildings with external fences of various constructions with limited heat supply are considered. A method has been developed for calculating the cooling rate of the inner surface of the outer fence and the temperature on this surface at a given point in time. Calculated dependencies are obtained to determine the acceptable duration of the heat supply system with limited heat supply. Application of the developed methodology can increase energy efficiency and contribute to the energy saving of buildings in the event of emergencies in the heat supply network.

Multidisciplinary fault diagnosis of complex engineering systems: A case study of nuclear power plants

Fault diagnosis is a key process in ensuring complex engineering system safety. It often requires collaborative and multidisciplinary efforts. This study seeks to understand the process of multidisciplinary fault diagnosis in complex engineering systems and the key human factors issues that impair this process. Data were collected from multidisciplinary diagnostic activities conducted in the commissioning phase of nuclear power plants (NPPs). In the first phase, we proposed a process model based on a combination of literature review, specialist interviews, and field observations. In phase two, the influencing issues identified in the first phase were assessed through a survey with 117 NPP commissioning specialists. Five factors influencing multidisciplinary fault diagnosis were identified: cognitive artifacts, diagnosis biases, preparation for multidisciplinary diagnosis, information sharing and collaborative reasoning, and collaborative decision-making. The significances of each factor were compared. The results provide guidance for the development of improvement measures to enhance the performance of multidisciplinary fault diagnosis. Practitioner summaryThe processes and influencing issues of multidisciplinary fault diagnosis during the commissioning phase of nuclear power plants were studied with field observations, interviews of 28 specialists, and a survey of 117 specialists. Five major influencing factors were identified, and their influences were compared.

System Safety Bookshelf

Mathematical Foundations of System Safety Engineering: A Road Map for the Future
 By Richard R. Zito

Machine Learning-Based Prognostics for Central Heating and Cooling Plant Equipment Health Monitoring

Fault detection, diagnostics, and prognostics (FDD&P) ensure the operation efficiency and safety of engineering systems. In the building domain, they can help significantly reduce energy consumption and improve occupant comfort. Specifically, prognostics are becoming increasingly important as a pro-active fault prevention strategy through continuously monitoring the health of energy systems. In this article, we develop a machine learning-based method for building systems. The proposed method can help develop predictive models from historical operation and maintenance data. After the detailed description of the proposed machine learning-based prognostic method, a case study involving prognostics on central heating and cooling plant (CHCP) equipment is provided. To this end, a year's worth of sensor and actuator data from four boilers and five chillers of a CHCP in Ottawa, Canada are collected. The plant operators are interviewed to understand how they handle failure events, and their logbooks are reviewed to extract the date and time of the recorded failure events. The sensor and actuator data up to two weeks prior to each of these failure events are used to develop regression tree models that predict time to failure (TTF). The results indicate that about half of the modeled failure events could be accurately predicted by looking at the data available in the distributed control system. Finally, the future work is outlined.

Research on the system function-structure analysis based on its implicit relation

To understand the system function-structure under different background relations, two analysis methods are proposed based on space fault tree and factor space theory. They are the system function-structure minimal disjunctive formula and the system function-structure simplest formula. The former establishes the axiom system of system function-structure analysis based on factor logic, and proves that the system function-structure obtained by function-structure analysis method is a minimal disjunction formula. The latter gives a more detailed analysis steps based on the former idea, which is mainly used to determine the implicit relation between system function and component function. The background sets consisting of the 16 and 32 background relations are studied with these two methods. The results show that the complete background relations can obtain a certain system function-structure uniquely; the incomplete background relations can obtain a family of certain system function-structures. If the incomplete background relations are a subset of the complete background relations, then the incomplete background relations must has a linear relation between functions to complement the incomplete background relations. At the same time, the system function equivalent and replacement relation are obtained. It is also proved that the system function-structure obtained from several subsets of the background sets is the simplest and the condition required for the simplest structure of the background set is strict. At present, the above methods are mainly used for system reliability analysis in safety system engineering.

Safe strategy for coal and gas outburst prevention in deep-and-thick coal seams using a soft rock protective layer mining

Coal and gas outburst is one of the most harmful disasters in coal mine production. With the increase of mining depth, all the coal seams in the deep-and-thick coal seam group will be upgraded to outburst coal seams, resulting in no suitable first mining layer can be selected as the protective layer. In this case, coal and gas outburst disasters are more serious and outburst prevention and control is more difficult. In order to alleviate the gas disaster and eliminate the risk of gas outburst, a safe strategy was proposed in this study. In this strategy, a suitable soft rock layer adjacent to deep-and-thick coal seams in the Luling coal mine of Huaibei coalfield was selected as the first protective mining layer after safety, economic and technical feasibility argument. Meanwhile, the stereoscopic gas extraction and utilization system safety engineering was established. The effect in the mining process practice of the soft rock protective layer was investigated and verified. Practice shows that this safe strategy can effectively reduce the outburst risk of strong outburst deep-and-thick coal seams and a large amount of pressure relief gas can be extracted and utilized. It can provide a new safety idea for efficient exploitation of coal and gas resources in deep-and-thick coal seams in China.

A Glance at Transit System Safety

System safety is a discipline of applying engineering and management principles, criteria, and techniques to achieve acceptable or tolerable risk within the constraints of operational effectiveness, suitability, time, and cost throughout all phases of the system life. System safety engineering is the program to identify hazards, and to eliminate hazards or reduce the associated risks when the hazards cannot be eliminated. System safety management involves plans and activities taken to identify hazards; assess and mitigate associated risks; track, control, close, and document risks encountered in the design, development, test, manufacturing, installation, operation and maintenance, and the disposal of systems, subsystems, and equipment. In this paper, the concept and principle of system safety in the transit system is discussed. The paper also introduces the safety standards, safety life-cycle, Safety Integrity Levels (SILs), safety analysis techniques and safety cases etc.

Safety at the edge: a safety framework to identify edge conditions in the future transportation system with highly automated vehicles

Automated driving systems (ADS) have the potential for improving safety but also pose the risk of extending the transportation system beyond its edge conditions, beyond the operating conditions (operational design...