Identification of safety and security critical systems and activities

There are many initiatives taken to identify safety and security critical systems and activities, at different levels and in different contexts, ranging from infrastructures at the societal level to equipment on the production plant level. Different approaches are implemented to define the critical systems and activities. Some of these relate to vulnerabilities, others incorporate the probability dimension and are risk based. We also see approaches taking into account values of the decision-maker and relevant stakeholders. In this paper, we discuss the rationale for these approaches. Is vulnerability an adequate measure to be used as a basis for determining criticality? Is it meaningful to specify safety and security critical systems and activities without addressing risk? How should we take into account the limitations of the risk assessments? Should we extend the concept of criticality to also cover utility aspects? We bring new insights into the discussion by being precise on the key risk concepts—including uncertainty, probability and expected value—and considering alternative risk perspectives. A novel approach is suggested based on expected values and uncertainties in underlying phenomena and processes. Our main concern is activities with potential severe consequences and large uncertainties.     

Variable delays and message losses: Influence on the reliability of a control loop

Today, new technologies (distributed systems, networks communication) are more and more integrated for applications needing to fit real-time and critical constraints. It means that we require more and more to integrate these new technology-based components in systems or sub-systems dedicated to safety or dealing with a high level of criticality.Control systems are generally evaluated as a function of required performances (overshoot, rising time, response time) under the condition to respect a stability condition. Reliability evaluation of such systems is not trivial, because generally classical methods do not take into account time and dynamic properties which are the bases of control systems.The methodology proposed in this paper deals with an approach for the dependability evaluation of control systems, based on Monte-Carlo simulation, giving a contribution to the integration of automatic control and dependability constraints.     

Cumulative fatigue damage dynamic interference statistical model

After studying in depth the statistical characteristics of cumulative fatigue damage D(t) and its critical value D_c, a new dynamic interference statistical model for fatigue reliability analysis is presented in this paper. Because the non-linearity of fatigue damage accumulation has been taken into account, this model is able to predict the fatigue reliability for random spectrum loading. To verify the predicted results, two fatigue experiments were conducted in which the numbers of specimens were more than 100, using fighter spectrum loading (FALSTAFF spectrum) and constant-amplitude loading respectively. It is shown that the new model is reliable, practicable and better than existing models.     

Lifecycle risk assessment of a technological system using dynamic Bayesian networks

Investigations of technological systems accidents reveal that technical, human, organizational, as well as environmental factors influence the occurrence of accidents. Despite these facts, most traditional risk assessment techniques focus on technical aspects of systems and have some limitations of incorporating efficient links between risk models and human and organizational factors. This paper presents a method for risk analysis of technological systems. Application of the presented framework makes it possible to analyze the influence of technical, human, organizational, and environmental risk factors on system safety. It encompasses system lifecycle from design to operational phase to give a comprehensive picture of system risks. The developed framework comprises the following main steps: (1) development of a conceptual risk analysis framework, (2) identifying risk influencing factors in different levels of technical, human, organizational, and environmental factors providing the possibility of analyzing interactions in a multi‐level system, (3) modeling system risk using dynamic Bayesian network (DBN), (4) assignment of probabilities and risk quantification in node probability tables (NPTs) based on industry records and experts extracted knowledge, (5) implementation of the model for wind turbines risk analysis combining use of V‐model, risk factors, and DBN in order to analyze the risk, and (6) analyzing different scenarios and the interactions in different levels. Finally, the various steps of the framework, the research objective fulfillment, and case study results are presented and discussed.     

Quantitative hazard and risk analysis for fragments of high-explosive shells in air

A hazard and risk analysis is given for personnel from primary fragments of fast moving and variably oriented high-explosive sources with spatially distributed event probability of a single event, e.g. for conventional threat. The approach assumes scenarios with static person densities on earth's surface. The spatial initiation distribution is described with a probability density function along a curve. The density can be constructed using expert estimates, technical safety analysis of an existing fuzing system or minimal technical safety requirements for fuzing systems. Arena test data are used for dynamic point source launching conditions of representative fragments to compute the physical consequences. Hazard criteria visualize the fragment density. Vulnerability models determine the individual local risk. In addition using the person density collective risks are computed. The individual and collective risks can be compared with various risk criteria, in particular for F-N curves. In a case study the approach is applied to a fuzing system of an artillery shell. Thus the post launch safety and the overhead safety or post safe separation safety taking third party into account are assessed. In this case the hazards and risks of fragments dominate when compared to blast effects. Assessing multiple scenarios the initiation density can be assessed.     

Managing risk dormancy in multi-team work: application of time-dependent success-and-safety assurance methodology

The success and safety of many of today's industrial activities, such as constructing power plants, transmission lines and civil engineering objects, is often influenced by situations, when successful and safe work completion is associated with the implementation of various more or less complex multi-team (MT) layouts. Multi-team effort is characterised by the presence and interaction of numerous, not necessarily concurrent time- and space-constrained interfering activities, as well as by dormant risks. Such risks might threaten the fulfilment of the general task carried out by the main team and/or by other teams on the construction site. This analysis addresses the role of the dormant risks during the fulfilment of a non-simultaneous MT work. The objective of the analysis is to suggest an effective and physically meaningful probabilistic predictive model. The model is aimed at the understanding, quantification and effectively managing the dynamics of the system of interest. The emphasis is on the role of possible dormancies. The study is an extension of the authors’ earlier research on spatial and time dimensions in the addressed problem. The study extends the risk management approach to a holistic level.

Relevance to human factors/ergonomics theory

This article characterises the risk dormancy phenomenon to be considered as a proper way of taking into account multi-team (MT) aspects in the occupational safety research. Furthermore, a holistic perception of MT functional complexity allows for a generalised view of MT mutual interaction instead of focusing in the single team behaviour.     

Risk analysis of the agri-food supply chain: A multi-method approach

Agri-food supply chains (AFSCs) are becoming more complex in structure, and thus more susceptible to different vulnerabilities and risks. Therefore, to enhance performance, we need to manage the risks in AFSCs effectively and efficiently. This study analyses various AFSC risks using a multi-method approach, including thematic analysis, total interpretive structural modelling (TISM) and fuzzy cross-impact matrix multiplication applied to classification (MICMAC) analysis. Based on the empirical data collected from experienced AFSC practitioners and following thematic analysis, eight categories of risk and 16 risk factors were identified as important. Furthermore, the interrelationships among the identified risks were built using TISM. Finally, the identified risks were classified into various categories according to their dependence and driving power using fuzzy MICMAC analysis. The research results indicate that the weather-related and political risks have the highest driving power and are located at the lowest level in the TISM hierarchy. These risks have a high tendency to disturb the whole flow of AFSC and so should be managed effectively. This study advances existing literature on identifying risk factors, defining interrelations between different AFSC risks, and determining the key risks. The risk analysis results can help AFSC practitioners in AFSC to identify, categorise and analyse the risks.     

A review of sociotechnical systems theory: a classic concept for new command and control paradigms

Command and control is the management infrastructure for any large, complex, dynamic resource system (Harris, C.J. and White, I., 1987. Advances in command, control and communication systems. London: Peregrinus). Traditional military command and control is increasingly challenged by a host of modern problems, namely, environmental complexity, dynamism, new technology and competition that is able to exploit the weaknesses of an organisational paradigm that has been dominant since the industrial revolution. The conceptual response to these challenges is a new type of command and control organisation called Network Enabled Capability (NEC). Although developed independently, NEC exhibits a high degree of overlap with concepts derived from sociotechnical systems theory, a fact that this paper aims to explore more fully. Uniquely, what sociotechnical theory brings to NEC research is a successful 50 year legacy in the application of open systems principles to commercial organisations. This track record is something that NEC research currently lacks. The paper reviews the twin concepts of NEC and sociotechnical systems theory, the underlying motivation behind the adoption of open systems thinking, a review of classic sociotechnical studies and the current state of the art. It is argued that ‘classic’ sociotechnical systems theory has much to offer ‘new’ command and control paradigms. The principles of sociotechnical systems theory align it exceptionally well with the challenges of modern organisational design. It is also reflective of a wider paradigm shift in ergonomics theory away from ‘industrial age’ modes of thought to systems-based ‘information age’ thinking.     

Quality risk management in pharmaceutical development

The objective of ICH Q8, Q9 and Q10 documents is application of systemic and science based approach to formulation development for building quality into product. There is always some uncertainty in new product development. Good risk management practice is essential for success of new product development in decreasing this uncertainty. In quality by design paradigm, the product performance properties relevant to the patient are predefined in target product profile (TPP). Together with prior knowledge and experience, TPP helps in identification of critical quality attributes (CQA’s). Initial risk assessment which identifies risks to these CQA’s provides impetus for product development. Product and process are designed to gain knowledge about these risks, devise strategies to eliminate or mitigate these risks and meet objectives set in TPP. By laying more emphasis on high risk events the protection level of patient is increased. The process being scientifically driven improves the transparency and reliability of the manufacturer. The focus on risk to the patient together with flexible development approach saves invaluable resources, increases confidence on quality and reduces compliance risk. The knowledge acquired in analysing risks to CQA’s permits construction of meaningful design space. Within the boundaries of the design space, variation in critical material characteristics and process parameters must be managed in order to yield a product having the desired characteristics. Specifications based on product and process understanding are established such that product will meet the specifications if tested. In this way, the product is amenable to real time release, since specifications only confirm quality but they do not serve as a means of effective process control.     

Driving under the influence of distraction: Examining dissociations between risk perception and engagement in distracted driving

Driving while distracted is a critical and unwavering problem in the United States leading to numerous injuries and fatalities each year. While increasing legislation and developing technological interventions strive to ensure we only focus on driving, individuals still drive distracted. We surveyed college-aged adults to examine the factors that influence both their risk perception of driving while distracted and how often they engage in distracting activities and situations while driving. We found a disassociation between individuals’ perception of driving distraction risk and their engagement with the distraction. Exposure, perceived knowledge of risks, fairness beliefs, and ratings of perceived visual and cognitive demands was associated with risk perception. Conversely, risk-seeking traits, how voluntary the task was perceived, and previous exposure to a distraction influenced engagement. Overall, we recommend additional research focusing on factors that predict engagement in driver distraction rather than perceived risk alone.     

Fuzzy-logic-based network for complex systems risk assessment: Application to ship performance analysis

In this paper, a new interpretation of intuitionistic fuzzy sets in the advanced framework of the Dempster–Shafer theory of evidence is extended to monitor safety-critical systems’ performance. Not only is the proposed approach more effective, but it also takes into account the fuzzy rules that deal with imperfect knowledge/information and, therefore, is different from the classical Takagi–Sugeno fuzzy system, which assumes that the rule (the knowledge) is perfect. We provide an analytical solution to the practical and important problem of the conceptual probabilistic approach for formal ship safety assessment using the fuzzy set theory that involves uncertainties associated with the reliability input data. Thus, the overall safety of the ship engine is investigated as an object of risk analysis using the fuzzy mapping structure, which considers uncertainty and partial truth in the input–output mapping. The proposed method integrates direct evidence of the frame of discernment and is demonstrated through references to examples where fuzzy set models are informative. These simple applications illustrate how to assess the conflict of sensor information fusion for a sufficient cooling power system of vessels under extreme operation conditions. It was found that propulsion engine safety systems are not only a function of many environmental and operation profiles but are also dynamic and complex.     

Selection of risk mitigation strategy in electronic supply chains using grey theory and digraph-matrix approaches

Supply chains are becoming more lengthy and complex due to globalisation and vertical integrations. In this context, adopting proactive approaches is needed for dealing with changing risks and vulnerabilities for securing supply chain systems. Supply chain risks are interlinked and thus, one mitigation strategy can reduce many of other supply chain risks. For example, aggregate or pooling demand reduces forecast risks, capacity risks and inventory risks. Also, some of the risk mitigation strategies have negative influences over certain supply chain risks as adding capacity has a negative influence on capacity risks. Twelve major supply chain risk categories and 21 risk mitigation strategies with typical focus on electronics manufacturing supply chains have been identified. A combination of grey theory and digraph-matrix methodologies has been used for quantifying various supply chain risk mitigation strategies and this approach is not seen in literature till date. The proposed model was also tested taking a case study of an Indian electronics manufacturing company. Obtained results were also subject to sensitivity analysis. The net positive influence values of risk mitigation strategies proposed in this research could effectively be used by top management for ascertaining their risk mitigation strategies for better management of supply chains as a whole.     

Risk of extreme events in the configuration of priority systems

This paper presents a reliability-based framework for the configuration of priority systems that control the risks of extreme transaction latencies. Modeling of priority systems can be computationally complex and lack robustness with respect to the feasible variations of such systems. The analyses tend to be ad hoc and overly particular to the application at hand. Furthermore, modeling of priority systems has focused on assessment of the average latencies, rather than on the potential for extremes of latency. The developed framework includes (i) a compact notation useful for modeling of priority systems, (ii) assessment of the risk of extreme latencies, and (iii) multiobjective analysis for the tuning of system parameters. An acceptable balance is sought among multiple risks of extreme transaction latencies. The framework is demonstrated in the configuration of an e-business server to minimize the lost transactions, e.g. ‘purchase’ requests for which a customer needs to wait longer than 8 s.     

Software reliability prediction: A survey

Softwares play an important role in controlling complex systems. Monitoring the proper functioning of the components of such systems is the principal role of softwares. Often, a petite fault in one of the subsystems may cause irreparable damages; therefore, it is of great importance to be able to predict software faults and estimate the reliability of softwares. In this survey, we present a classification of various methods proposed in the literature to predict software reliability. This study summarizes the results of more than 200 research papers in the field. We also discuss the challenges involved in prediction methods along with proposed partial solutions (i.e., Bayesian methods) to improve the accuracy of such predictions. Moreover, we review numerous evaluation measures introduced so far to assess the performance of prediction models, the datasets they are based on, and also the results they yield.     

Analytic Critical Flow Method (ACFM): A Reliability Allocation Method Based on Analytic Hierarchy Process

RAMS is an acronym for reliability, availability, maintainability and safety. These four properties concern the application of important methodologies to design and manage complex systems. In the present research, starting from the analysis of several literature reliability allocation techniques, a reliability allocation method has been implemented called analytic critical flow method (ACFM). Critical flow method is a reliability allocation method for series-parallel configurations, based on failure analysis of each unit of the system. The new approach is based on critical flow method, whose results are matched with the analytic hierarchy process multicriteria method. The result is a dynamic model that combines the advantages of the allocation method and the multicriteria approach. The need to develop the ACFM is the outcome of a careful analysis of the current military and commercial approaches. In particular, no literature method takes into account to assign a different level of significance (weight) to the different units of the system, simultaneously to the considered factors. The proposed approach has been applied and compared with other traditional methods on an aerospace prototype (series-parallel configuration), where the reliability allocation process is rigorous. The results demonstrate the effectiveness of the new approach and its ability to overcome the criticalities highlighted in literature.     

Overview of the key risks in the pioneering stage of the Malaysian biomass industry

Renewable energy sources have increasingly become important in recent decades not only as ways for improving energy security and mitigating climate change, but they also help contribute to economic growth and job creation. As the second-largest producer of crude palm oil, Malaysia has abundance of biomass residues from palm oil industries and other renewable organic matters which can be converted to bio-energy and bio-chemicals. Recognizing the roles of biomass for sustainability and wealth creation, the government has stepped up efforts to promote the growth of the industry. However, despite institutional arrangements, policy frameworks, funding mechanisms and incentives to support the growth of the biomass industry, the industry has not been able to create value along the industry’s value chain. While there are many attractive reasons to venture into the biomass industry, there are also potential risks. Lack of understanding of risks associated with the biomass industry is often cited as one of the reasons for the industry’s slow growth. An industry evolves through life cycle stages and at each stage presents risk factors. This paper identifies several key risks associated with early stage of the biomass industry in Malaysia. The overview of risks associated with the biomass industry not only will provide a perspective from which an industry’s viability can be evaluated but also will help industry participants to better understand key risks and improve their risk assessment methods as well as plan their risk management and mitigation strategies more effectively.     

Management of sustainable manufacturing systems-a review on mathematical problems

The ever-growing awareness of environmental protection has significantly influenced the method of manufacturing products. Due to the introduction of new processes, the management of sustainable manufacturing shows different characteristics to those of traditional systems. Sustainable manufacturing systems have attracted a great deal of attention in the past 20 years as an emerging manufacturing approach. Particularly in the last 10 years, the number of papers focusing on the topic of sustainable manufacturing systems’ management has increased rapidly. More and more practical factors have been considered and integrated into this area which makes it more complex, but closer to reality. This paper aims to classify the mathematical problems dealing with the management of sustainable manufacturing systems. More than 100 related papers mainly from 1994 to 2015 have been selected and reviewed and divided into three categories according to the main elements in a manufacturing system: production planning and control, inventory management and control and manufacturing network design. The development of each category is summarised and the corresponding mathematical problems are discussed to provide a general overview of the relevant research fields and identify future research directions.     

非经典阻尼分布参数系统复振型叠加方法

附加减震装置的一维杆或剪切梁模型属于非连续的非经典阻尼分布参数系统.对于它的动力分析,通常是建立分段的运动方程,然后利用各段动力反应的实振型叠加形式和连续条件进行动力计算.这是一种实模态综合方法,尽管它可以求得近似的动力反应,但反映不出阻尼对整体系统动力特性的影响.为了考虑附加减震装置引起的阻尼和刚度非连续性,基于广义...     

On optimal upgrade strategy for second-hand multi-component systems sold with warranty

Reliability improvement strategies such as upgrade, reconditioning and remanufacturing have been extensively adopted by dealers of second-hand systems to improve the system reliability and reduce the warranty servicing cost. However, most existing studies on this topic do not consider the multi-component structures of complex second-hand systems, and either treat them as black-box systems by ignoring their internal structures or simply deal with individual components. In this paper, a new upgrade model is developed for complex second-hand systems sold with a non-renewing free repair/replacement warranty, by explicitly considering their multi-component configurations. Two types of components, i.e. repairable and non-repairable components, are taken into account. During the upgrade process, non-repairable components can be upgraded only by replacement (if necessary), while repairable ones may be imperfectly upgraded with various degrees. The main objective of the dealer is to determine which components to upgrade and the corresponding upgrade degrees, to minimise the total expected servicing cost. In view of the problem structure, a marginal analysis based algorithm is presented. It is shown that the proposed upgrade strategy contains the ‘no upgrade’ strategy and the ‘component-level perfect upgrade/replacement’ strategy as special cases, and outperforms them. Finally, several extensions of the proposed upgrade model are discussed.