System Safety Assessment Research Articles

Operational safety assessment of straddle-type monorail vehicle system based on cloud model and improved CRITIC method

This paper proposes an improved critic method and establishes an operational safety assessment method for straddle-type monorail vehicle system based on cloud model and improved critic method. Firstly, according to the structure and function of straddle- type monorail vehicle system, the reliability index system of straddle-type monorail vehicle is established, and the weight value of reliability evaluation index is determined by improved critic method. Then, the cloud model expression of reliability evaluation index of straddle-type monorail vehicle system is obtained by virtual cloud. finally, similarity analysis is conducted between the new cloud of straddle-type monorail vehicle system reliability comprehensive index and the cloud model of reliability evaluation set, so as to judge that the comprehensive cloud model of straddle-type monorail vehicle system can be used to evaluate the operation status of “main functions” of the system. The analysis shows that the reliability evaluation method of straddle-type monorail vehicle system based on cloud model and improved critic method can correctly describe the daily operation of straddle-type monorail vehicle system in Chongqing, which provides a method reference for reliability evaluation of straddle-type monorail vehicle system.

Groundwater circulation patterns in bedrock aquifers from a pre-selected area of high-level radioactive waste repository based on two-dimensional numerical simulation

Deep geological disposal is internationally accepted as a feasible and safe way to dispose the high-level radioactive waste (HLW) in low permeability fractured bedrocks. It is essential to understand the regimes of groundwater flow, circulation, and predict the characteristics of long-term flow systems for site selection and safety assessment of deep geological HLW disposal by using numerical simulation technology. In this study, TOUGH3/EOS9 software with an improved evaporation module is used to develop a two-dimensional variably saturated numerical model of a typical profile at Xinchang site, which is considered as a potential deep geological repository for spent HLW in China. Results reveal that almost 99% of the precipitation is discharged through evaporation, and less than 1% infiltrates into shallow groundwater. The groundwater flow pattern is closely related to topography and lithological distribution, and the groundwater flow in Xinchang rock mass cannot discharge to the south Hexi Corridor. Groundwater in the typical profile is divided into three types of groundwater flow system, namely local, intermediate and regional flow system, and each has its own characteristics based on aspects of flow path, cycle amount, cycle path, residence time and discharge position. The circulation flux of these three systems accounts for 79.25%, 13.24% and 7.51% of the total groundwater quantity of Xinchang site, respectively. Meanwhile, different-depth models were constructed to validate the influence of bottom boundary depths on groundwater characteristics. Increasing the bottom boundary depth has limited influence on the maximum circulation depth of regional flow system, but negligible impact on circulation flux. This study can enhance the understanding of groundwater circulation and evolution in fractured bedrock aquifers with low permeability, and provide the feasibility of geological repository for spent HLW for the view point of groundwater flow.

SMART SKY EYE System for Preliminary Structural Safety Assessment of Buildings Using Unmanned Aerial Vehicles.

The development of unmanned aerial vehicles (UAVs) is expected to become one of the most commercialized research areas in the world over the next decade. Globally, unmanned aircraft have been increasingly used for safety surveillance in the construction industry and civil engineering fields. This paper presents an aerial image-based approach using UAVs to inspect cracks and deformations in buildings. A state-of-the-art safety evaluation method termed SMART SKY EYE (Smart building safety assessment system using UAV) is introduced; this system utilizes an unmanned airplane equipped with a thermal camera and programmed with various surveying efficiency improvement methods, such as thermography, machine-learning algorithms, and 3D point cloud modeling. Using this method, crack maps, crack depths, and the deformations of structures can be obtained. Error rates are compared between the proposed and conventional methods.

Study on the logical relationship between system safety and PMMEL project

Abstract The Master Minimum Equipment List (MMEL) is an important technical manual for civil aircraft to meet release conditions and achieve release with failures, and it is also a key reference manual for airlines to develop the minimum equipment list. This paper firstly elaborates the relationship between PMMEL, MMEL and MEL, initially studies the system safety assessment process, and focuses on the logical relationship between system safety and PMMEL project development by detailing the role of system safety assessment FHA, FMEA and FTA in the development and analysis process of PMMEL during the aircraft development phase, to ensure the PMMEL work and The logical relationship between system safety and PMMEL project development is discussed to ensure the close integration between PMMEL work and civil aircraft development, to provide theoretical basis for manufacturers to fully consider the design of PMMEL in the development phase, and then to improve the capability of the developed aircraft with failure release.

Fire safety assessment of sprinkler systems for car parks using the J-value methodology

A J-value assessment was carried out to quantify the costs and benefits of sprinkler system installation in car parks, both with respect to life safety and property protection. Nine scenarios were established based on collected input data. All car park types were considered for the USA, England, Scotland, Wales and the UK nations collectively, while separate considerations were made for multi-storey car parks (MSCPs) in the UK and for MSCPs, underground and other parking types in England.Even when assuming 100% sprinkler effectiveness, the J-values for the nine scenarios were all larger than unity (ranging from 5 to 555), thus indicating that the installation of sprinklers is not a cost-effective investment for car parks from a societal point of view. The analysis showed that different car park types must be treated separately, due to specifics of structure and fire statistics. The lowest J-values were obtained for MSCPs and underground car parks. Sprinkler installation mainly provides property protection benefits, because of property loss savings substantially outweigh those associated with life safety.Even though sprinklers were not cost-effective for car parks in the current analysis, the scarcity of data and new emerging technologies suggests that further investigation is needed.

Development of local-scale high-resolution atmospheric dispersion and dose assessment system

ABSTRACT We have developed a local-scale high-resolution atmospheric dispersion and dose assessment system (LHADDAS) for safety and consequence assessment of nuclear facilities and emergency response to nuclear accidents or deliberate release of radioactive materials in built-up urban areas. This system comprises three parts: preprocessing of input files and main calculation by a local-scale high-resolution atmospheric dispersion model using large-eddy simulation (LOHDIM-LES) and a real-time urban dispersion simulation model based on a lattice Boltzmann method (CityLBM), and postprocessing of dose calculation by a simulation code powered by lattice dose-response functions (SIBYL). LHADDAS has a broad utility and performs excellently in (1) simulating turbulent flows, plume dispersion, and dry deposition under realistic meteorological conditions; (2) simulating real-time tracer dispersion using a locally mesh-refined lattice Boltzmann method; and (3) estimating the air dose rates of radionuclides from air concentrations and surface deposition in consideration of the influence of individual buildings and structures. This system is promising for use in the safety assessment of nuclear facilities (as an alternative to wind tunnel experiments), detailed pre/post-analyses of local-scale radioactive plume dispersion in case of nuclear accidents and quick response to emergencies resulting from the deliberate release of radioactive materials by terrorist attacks in central urban district areas.

An application of fault tree analysis for computing the bounds on system failure probability through qualitative data in intuitionistic fuzzy environment

AbstractFor the safety assessment of complex engineering systems, fault tree analysis (FTA) is a widely used method and can be performed only when all its basic events (BEs) have their corresponding failure data. However, in many applications, obtaining precise quantitative failure data of all the components of the system is not feasible due to changing environment, insufficient data or new components. The present research develops a novel FTA to identify the best estimate and bounds of system failure probability through qualitative data processing. The failure data of BEs are uncertain therefore expert elicitation method is used incorporating intuitionistic fuzzy (IF) set theory to evaluate the top event failure probabilities. The novelty of the proposed work comes with the use of linguistic values as failure possibilities of the system components and utilizing triangular intuitionistic fuzzy numbers (TIFNs) to quantify the linguistic terms into mathematical form to assess the best‐estimated value of the system failure probability, and also the lower bound and the upper bound of the system failure probability. To exemplify the appropriateness of the proposed study, the case studies Combustion Engineering Reactor Protection System (CERPS) and Emergency Core Cooling System (ECCS) are carried out and a comparison between computed results and outcomes from the previous methods is demonstrated. The results are exceptionally near to the outcomes of conventional FTA, which confirms that the proposed procedure is a real substitute in the IF environment when components have imprecise quantitative failure data.

FEM verification of accelerated vibration test method based on Grms - T curve

Accelerated random vibration test is now the important dynamic performance and safety evaluation technique for transport packaging system during transportation. The current widely used time scale of accelerated random vibration test in engineering test and some standards is “Inverse power law,” which is based on Basquin (power function) fatigue damage model and [Formula: see text] curve, but is not completely suitable for transport packaging system. In author’s previous research, the general theory of accelerated random vibration test based on acceleration PSD and [Formula: see text] curve was developed which is applied for any fatigue damage model besides Basquin type. The study in this paper is the further and extensive research of previous research. The definite expression between response von Mises equivalent stress ([Formula: see text]) of the products and tri-axial acceleration Root-Mean-Square (RMS) was developed, based on which [Formula: see text] curve was transformed to [Formula: see text] curve to describe the product damage. Time scale of accelerated random vibration was obtained. The proposed method was verified by finite element analysis. In addition, the effects of excitation spectrum shape and system damping on the response vibration of products were discussed. This study is valuable in engineering for safety assessment and random vibration analysis of transport packaging system.

Safety Assessment of Technical Objects and Systems Using Fuzzy Logic Methods

To assess and analyze safety of engineering facilities, systems and the level of risks in the manmade environment, it is often necessary to study the influence of various weakly formalized factors. In this case, when modeling risk, it is advisable to use methods of fuzzy logic. Fuzzy methods make it possible to represent risk, defined as a combination of the probability of an emergency and the measure of its consequences, as a function of fuzzy variable. This makes it possible to develop fuzzy models describing the relationship between parameters of technical facilities and their safety level in accordance with various risk criteria. The paper provides examples of assessing the influence of the reliability of a technical system on the level of societal risk for personnel as well as the influence of the level of facility protection on the level of risk generated by it. The aspects of formalization of indicators characterizing the reliability of the human operator are also considered. These aspects are further used for modeling risk. The considered procedures can be made more sophisticated by expanding the space of factors, taking into account linkages among them and embedding the obtained fuzzy sets into a hierarchical cognitive risk model.

A Comparative Review of the Current Methods of Analysis and Design of Stiffened and Unstiffened Steel Liners

There are significant levels of concern about both the safety assessment and financial evaluation of the whole hydropower system, especially at early project stages. In addition, there is a variety of reliable and accurate methods for analysis, design, and optimization of steel pressure liners in hydropower plants. Several countries have developed specific regulations and codes for the design, installation, and safety evaluation of under-pressure piping, as well as estimates of the potential risks associated with failure. This paper reviews the current methodologies and codes available for design and safety assessment of either unstiffened or stiffened pressure steel liners in hydropower plants. After examining the main guidelines and practical conclusions drawn from recent research in the field of liners subjected to either internal or external pressure, this article then discusses the relevant regulations and codes. The scope of this work is to summarize the advantages, disadvantages, and main characteristics of the existing design criteria, analysis methods, and other issues related to steel liners. Afterwards, this paper compares the main reliable formulations and modelling techniques, even the most recent or sophisticated ones. Lastly, we draw some conclusions regarding their accuracy and scope of applicability.

System safety assessment with efficient probabilistic stability analysis of engineered slopes along a new rail line

System safety assessment with efficient probabilistic stability analysis of engineered slopes along a new rail line

Safety assessment of the process Green Loop System, used to recycle polycyclohexylene dimethylene terephthalate glycol-modified (PCTG) plates for use as food contact materials.

The EFSA Panel on Food Contact Materials, Enzymes and Processing Aids (CEP) assessed the safety of the recycling process Green Loop System (EU register number RECYC174), a closed and controlled product loop. The input consists of washed plates of polycyclohexylene dimethylene terephthalate glycol‐modified (PCTG) having been used in, e.g. canteens. The plates are ground, converted to new plates, returned to the users of the loop and used as before recycling. The management system to ensure a closed loop is critical, i.e. compliance of the origin of the input with Commission Regulation (EC) No 282/2008 and full traceability from input to final product should be ensured. The Panel concluded that the input of the process Green Loop System originates from product loops that are in a closed and controlled chain, designed to ensure that only materials and articles that have been intended for food contact are used and that contamination other than by food can be ruled out. The recycling process Green Loop System is, therefore, able to recycle PCTG plates intended for repeated use, for contact with aqueous, acidic and fatty food, at low and high temperatures.

Handling Uncertainty in Human Cognitive Reliability Method for Safety Assessment Based on DSET

Human Reliability Analysis (HRA) is an important part in safety assessment of a large complex system. Human Cognitive Reliability (HCR) model is a method of evaluating the probability that operators fail to complete during diagnostic decision making within a limited time, which is widely used in HRA. In the application of this method, cognitive patterns of humans are required to be considered and classified, and this process often relies on the evaluation opinions of experts which is highly subjective and uncertain. How to effectively express and process this uncertain and subjective information plays a critical role in improving the accuracy and applicability of HCR. In this paper, a new model was proposed to deal with the uncertain information which exists in the processes of cognitive pattern classification in HCR. First, an evaluation panel was constructed based on expert opinions and processing including setting corresponding anchor points and qualitative indicators of different cognitive patterns, and mapping them to fuzzy numbers and unit intervals. Second, based on the evaluation panel, different analysts judge the cognitive pattern types of actual specific events and provide the level of confidence he or she has in the judgments. Finally, the evaluation opinions of multiple analysts were expressed and fused based on the Dempster-Shafer Evidence Theory (DSET), and the fused results were applied to the HCR model to obtain the Human Error Probability (HEP). A case study was used to demonstrate the procedure and effectiveness of the proposed method.

Identification of Failure Modes in the Collision Avoidance System of an Autonomous Ferry using Adaptive Stress Testing

As complex autonomous systems emerge in the maritime sector, measures must be taken in order to ensure thorough safety assessment. Real-world testing can be costly and potentially dangerous, and therefore there is a need for suitable simulation-based methods. This paper presents an implementation of the Adaptive Stress Testing (AST) method applied to the collision avoidance (COLAV) system of a small passenger ferry. AST is a simulation-based technique which has shown promising results in safety assessment of aviation and automobile systems. Given a simulator of a system, AST uses reinforcement learning to optimize toward system failure, and returns the most likely failure scenarios. AST is here shown to successfully identify scenarios where the criteria for failure are met, which is when the ferry collides with an adversary vessel controlled by AST. However, most of the initial results exhibit failures where the COLAV system of the ferry is not responsible for the failure, making the results less valuable to system developers. To improve the relevance, augmentations are made to the optimization problem. The augmentations result in four distinct problem formulations presented in the paper. Finally, the results are clustered using an unsupervised machine learning method called Soft Dynamic Time Warping k-means clustering in order to present a general summary of the identified failure scenarios. Our results demonstrate the relevance and potential of AST for the maritime sector and illustrate how common drawbacks of AST can be circumvented by method adjustment.

In vivo integrated safety assessment of the cardiovascular system in drug development

Drug-induced cardiotoxicity still remains a major cause of concern, and non-clinical integrated risk assessments from both functional and structural alterations in the cardiovascular system are strongly required in the creation of drugs with superior safety profiles. Although systemic blood pressure, heart rate, and electrocardiogram are the main items in safety pharmacology studies, direct cardiac function assessments such as cardiac output and ventricular contractility, mentioned in ICH S7A guideline, are also desirable. General toxicology studies are important to detect structural changes through clinical pathology and histopathological examination, and translational biomarkers and metabolomics analysis with high extrapolation to humans also provide useful insights. In this paper, we will introduce our basic research to investigate the cardiac effects of milrinone, a cAMP phosphodiesterase III inhibitor in cynomolgus monkeys, and share the importance of comprehensive risk assessment in non-clinical in vivo studies.

IMPROVEMENT OF IMMUNOLOGICAL RESEARCH METHODOLOGY IN THE SYSTEM OF NOVEL FOOD SAFETY ASSESSMENT

Immunological studies have an important role in the comprehensive safety assessment of novel food. This publication presents the data of the experiment with different doses of ovalbumin, that confirms the informative value of the study of morphological indicators of the immune system’s organs (thymus, spleen, Payer's patch).

Prospective molecular methods for sequencing microorganisms in the system of assessment and control of food safety

To solve one of the most important tasks of food hygiene - ensuring foodstuff biosafety, the leading place is given to the use of nucleic acid sequencing methods that allow to identify and describe the nucleotide sequences of genomes both in individual microorganisms and metagenomic characteristics of microbial communities in environmental objects, in humans and animals. The purpose of the review was to analyze the main areas of sequencing application in food microbiology, biotechnology and epidemiology. Material and methods. The collection and analysis of scientific and informational materials published in domestic and foreign publications from Scopus, Web of Science, PubMed, RSCI databases, official reports of the World Health Organization (WHO), the European Food Safety Agency (EFSA) and other published sources has been carried out. Results. The review presents generalized characteristics of the most well-known sequencing formats based on different principles of reading and processing genetic information: capillary sequencing by Sanger, pyrosequencing, sequencing by ligation, sequencing by DNA synthesis, semiconductor high-performance sequencing, sequencing of individual DNA molecules. It is shown that multilocus analysis (MLST, MLVA) increases the specificity of genotyping and intraspecific identification of food-borne pathogens. It is used to assess the pathogenic potential and study the mechanisms of evolutionary variability of bacterial pathogens, leading to polymorphism of clonal lines and the appearance of strain-specific differences, to monitor the different genotypes of pathogens in production and other objects of the food chain. Nanopore sequencing is promising for studying bacterial plasmids and localization of resistance genes of MDR bacteria. Genome-wide analysis (WGS) makes it possible to identify detailed characteristics of pathogens of infectious diseases, including uncultivated and previously unknown microorganisms, as well as to study the features of the organization of individual pro- and eukaryotic genomes, gene regulation systems, pathogenicity factors and protein expression. The role of WGS methods for determining the degree of genetic kinship of infectious agents isolated from various sources in the investigation of outbreaks and sporadic food poisoning and infections is shown. The possibilities of metagenomic sequencing in the study of species composition, genetic diversity and metabolic potential of microbial communities are demonstrated. The main advantage of metagenomics is the possibility of direct sequencing of the genomes of microorganisms living in the human body, animals, water, soil and other objects. Metagenomic analysis plays a leading role in the detection of unexplored taxa, uncultivated and difficult-to-cultivate forms of a wide range of microorganisms. The most important direction of metagenomics is the study of the human or animal microbiome, the analysis of the relationship between the intestinal microbiota and metabolism, as well as the formation of the nutritional status of a person. Theoretical and practical aspects of the implementation of high-performance sequencing methods in the system of food biosafety assessment and control are reviewed: safety assessment of genetically modified strains of food producers, development of fundamentally new algorithms for investigating outbreaks of infectious diseases, creation of network systems for early diagnosis and notification of food infections of bacterial and viral etiology. Conclusion. Sequencing should become a standard methodology in the field of food safety for the identification and characterization of food pathogens, including those with resistance to antibiotics and adverse technological effects. The introduction of WGS into the food safety assessment and control system will make it possible to assess real food contamination with new and newly returning pathogens, create electronic databases and scientifically substantiate the most adequate measures for the prevention of food infections and ensuring the health of the population.

Consistency Analysis of Large-scale Energy Storage Batteries

With the development of large-scale electrochemical energy storage power stations, lithium-ion batteries have unique advantages in terms of re-energy density, power density, and cycle life, and are applied to power system energy storage devices. However, behind the rapid development, there are many key issues unanswered, which are likely to lead to various safety accidents. Therefore, it is very important to conduct consistency analysis of lithium batteries used in large-scale power systems to prepare for system safety assessment. This paper mainly explains the reasons and manifestations of the inconsistency, and based on data mining algorithms, uses the charging voltage curve clustering analysis method based on subtractive clustering to evaluate the consistency of lithium-ion batteries.

Defining Reasonably Foreseeable Parameter Ranges Using Real-World Traffic Data for Scenario-Based Safety Assessment of Automated Vehicles

Verification and validation of automated driving systems’ safety are some of the biggest challenges for the introduction of automated vehicles into the market. Scenario-based safety assessment is an efficient and repeatable method to test the systems’ safety before their deployment in the real world. However, even with limited traffic situations identified as critical to the system behavior, there is still an open range of parameters to describe each situation. Thus, defining specific parameter ranges is crucial to realize the scenario-based safety assessment approach. This study proposes a method to parameterize scenarios extracted from real-world traffic data, analyze their distribution and correlation, and incorporate them into the definition of reasonably foreseeable parameter ranges through the contextualization of resulting ranges with reasonable risk acceptance thresholds from different fields and international environments. Representative values can be selected from these specific parameter ranges to extract specific concrete scenarios applicable for the systems safety assessment. The applicability of the proposed method is demonstrated using parameter ranges obtained to define two sets of 960 cut-in and 6,442 deceleration scenarios extracted from a new set of traffic data collected from Japanese highways under the SAKURA initiative. The outcomes will enable comparisons with traffic data from other countries and inform automated driving system developers, standardization bodies, and policymakers to develop automated vehicle safety assessments applicable internationally.

RESULTS OF TOXICOLOGICAL STUDIES OF NOVEL FOOD OBTAINED FROM HERMETIA ILLUCENS LARVAE IN AN EXPERIMENT ON 2 GENERATIONS OF RATS

Comprehensive toxicological studies conducted as part of the safety assessment system's development for novel food derived from insects, included an experiment on 2 generations of Wistar rats.