Seismic safety assessment with non-Gaussian random processes for train-bridge coupled systems

Extensive high-speed railway(HSR)network resembled the intricate vascular system of the human body,crisscrossing mainlands.Seismic events,known for their unpredictability,pose a significant threat to both trains and bridges,given the HSR’s extended operational duration.Therefore,ensuring the running safety of train-bridge coupled(TBC)system,primarily composed of simply supported beam bridges,is paramount.Traditional methods like the Monte Carlo method fall short in analyzing this intricate system efficiently.Instead,efficient algorithm like the new point estimate method combined with moment expansion approximation(NPEM-MEA)is applied to study random responses of numerical simulation TBC systems.Validation of the NPEM-MEA’s feasibility is conducted using the Monte Carlo method.Comparative analysis confirms the accuracy and efficiency of the method,with a recommended truncation order of four to six for the NPEM-MEA.Additionally,the influences of seismic magnitude and epicentral distance are discussed based on the random dynamic responses in the TBC system.This methodology not only facilitates seismic safety assessments for TBC systems but also contributes to standard-setting for these systems under earthquake conditions.

Safety assessment of a novel marine multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 according to phenotype and whole genome-sequencing analysis

The application of microorganisms as probiotics is limited due to lack of safety evaluation.Here,a novel multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 with aroma-producing properties was identified from marine mangrove microorganisms.Its safety and probiotic properties were assessed in accordance with phenotype and whole-genome sequencing analysis.Results showed that the genes and phenotypic expression of related virulence,antibiotic resistance and retroelement were rarely found.Hyphal morphogenesis genes(SIT4,HOG1,SPA2,ERK1,ICL1,CST20,HSP104,TPS1,and RHO1)and phospholipase secretion gene(VPS4)were annotated.True hyphae and phospholipase were absent.Only one retroelement(Tad1-65_BG)was found.Major biogenic amines(BAs)encoding genes were absent,except for spermidine synthase(JA9_002594),spermine synthase(JA9_004690),and tyrosine decarboxylase(inx).The production of single BAs and total BAs was far below the food-defined thresholds.GXDK6 had no resistance to common antifungal drugs.Virulence enzymes,such as gelatinase,DNase,hemolytic,lecithinase,and thrombin were absent.Acute toxicity test with mice demonstrated that GXDK6 is safe.GXDK6 has a good reproduction ability in the simulation gastrointestinal tract.GXDK6 also has a strong antioxidant ability,β-glucosidase,and inulinase activity.To sum up,GXDK6 is considered as a safe probiotic for human consumption and food fermentation.

A novel refined dynamic model of high-speed maglev train-bridge coupled system for random vibration and running safety assessment

Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.

Demonstration of safety characteristics and effects on gut microbiota of Lactobacillus gasseri HMV18

Human normal flora is a source of probiotics.The safety characteristics of a specific isolate determine its application in foods or drugs.The food-borne-pathogen antagonist strain Lactobacillus gasseri HMV18 is one of the isolates from normal human flora.In this work,we assessed the in vitro pH tolerance,bile tolerance,biogenic amine production,mucin utilization,and safety of in vivo administration to mice to evaluate general health,organ-body weight index,organ histopathological change,whether L.gasseri HMV18 can colonize in the gut or modulate the gut microbiota after oral administration.The results suggest that L.gasseri HMV18 can tolerate pH 3 for 2 h,3%bile for 3 h,biogenic amine negative,mucin usage negative,does not encode verified toxins,and cause no visible change in mice's organs.L.gasseri HMV18 might not colonize in mice's gut,but can significantly affect the structure of gut microbiota.A bibliographical survey suggested that there were as few as 8 opportunistic infection cases from 1984 to 2022 and that the possibility for L.gasseri to cause infection is relatively low.Therefore,this work provides a basis for the foods or drugs application of L.gasseri HMV18 and gives a map of experiments for the safety assessment of probiotics.

Risk identification and safety assessment of human-computer interaction in integrated avionics based on STAMP

To solve the problem of risk identification and quantitative assessment for human-computer interaction(HCI)in complex avionics systems,an HCI safety analysis framework based on system-theoretical process analysis(STPA)and cognitive reliability and error analysis method(CREAM)is proposed.STPACREAM can identify unsafe control actions and find the causal path during the interaction of avionics systems and pilot with the help of formal verification tools automatically.The common performance conditions(CPC)of avionics systems in the aviation environment is established and a quantitative analysis of human failure is carried out.Taking the head-up display(HUD)system interaction process as an example,a case analysis is carried out,the layered safety control structure and formal model of the HUD interaction process are established.For the interactive behavior“Pilots approaching with HUD”,four unsafe control actions and35 causal scenarios are identified and the impact of common performance conditions at different levels on the pilot decision model are analyzed.The results show that HUD's HCI level gradually improves as the scores of CPC increase,and the quality of crew member cooperation and time sufficiency of the task is the key to its HCI.Through case analysis,it is shown that STPACREAM can quantitatively assess the hazards in HCI and identify the key factors that impact safety.

Analysis of Safety Assessment and Testing of Heavy Traffic Vehicles on Old Bridges Without Data

This article presents a real-life project that aimed to evaluate the safety of traffic vehicles on old bridges without any prior data.The project involved various safety inspections,including conventional,static,and dynamic load inspections and safety assessments.After conducting these tests,it was concluded that the structure of the old bridge is relatively safe,with only a few bumps.The bridge could function normally following appropriate treatment.The analysis provides valuable insights into the assessment of the quality and safety of such bridges to ensure the safe driving of heavy vehicles.

Safety Risk Assessment Analysis of Bridge Construction Using Backpropagation Neural Network

The evaluation of construction safety risks has become a crucial task with the increasing development of bridge construction.This paper aims to provide an overview of the application of backpropagation neural networks in assessing safety risks during bridge construction.It introduces the situation,principles,methods,and advantages,as well as the current status and future development directions of backpropagation-related research.

NEW METHOD FOR SAFETY ASSESSMENT OF PARALLEL ROUTES

A new safety assessment method for parallel routes is presented. From the aspects of safety guard system of air traffic control（ATC） and considering the flight conflict as causing event of air collision accidents, this paper fosters a four-layer safety guard of controller command, short-term conflict alerts （STCAs）, pilot visual avoidance, and traffic alert collision avoidance system（TCAS）. Then, the problem of parallel routes collision risk is divided into two parts：the calculation of potential flight conflict and the analysis of failure probability of the four-layer safety guard. A calculation model for controller interference times is induced. By using cognitive reliability and error analysis method（CREAM）,the calculation problem to failure probability of controller sequencing flight conflicts is solved and a fault tree model of guard failure of STCA and TCAS is established. Finally, the Beijing-Shanghai parallel routes are taken as an example to be calculated and the collision risk of the parallel routes is obtained under the condition of radar control. Results show that the parallel routes can satisfy the safety demands.

Overcharge-to-thermal-runaway behavior and safety assessment of commercial lithium-ion cells with different cathode materials:A comparison study

In this paper,overcharge behaviors and thermal runaway(TR)features of large format lithium-ion(Liion)cells with different cathode materials(LiFePO4(LFP),Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2)(NCM111),Li[Ni_(0.6)Co_(0.2)Mn_(0.2)]O_(2)(NCM622)and Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM811))were investigated.The results showed that,under the same overcharge condition,the TR of LFP Li-ion cell occurred earlier compared with the NCM Li-ion cells,indicating its poor overcharge tolerance and high TR risk.However,when TR occurred,LFP Li-ion cell exhibited lower maximum temperature and mild TR response.All NCM Liion cells caught fire or exploded during TR,while the LFP Li-ion cell only released a large amount of smoke without fire.According to the overcharge behaviors and TR features,a safety assessment score system was proposed to evaluate the safety of the cells.In short,NCM Li-ion cells have better performance in energy density and overcharge tolerance(or low TR risk),while LFP Li-ion cell showed less severe response to overcharging(or less TR hazards).For NCM Li-ion cells,as the ratio of nickel in cathode material increases,the thermal stability of the cathode materials becomes poorer,and the TR hazards increase.Such a comparison study on large format Li-ion cells with different cathode materials can provide deeper insights into the overcharge behaviors and TR features,and provide guidance for engineers to reasonably choose battery materials in automotive applications.

Study of a Comprehensive Assessment Method for Coal Mine Safety Based on a Hierarchical Grey Analysis

Coal mine safety is a complex system, which is controlled by a number of interrelated factors and is difficult to estimate. This paper proposes an index system of safety assessment based on correlated factors involved in coal mining and a comprehensive evaluation model that combines the advantages of the AHP and a grey clustering method to guarantee the accuracy and objectivity of weight coefficients. First, we confirmed the weight of every index using the AHP, then did a general safety assessment by means of a grey clustering method. This model analyses the status of mining safety both qualitatively and quantitatively. It keeps management and technical groups informed of the situation of the coal production line in real time, which aids in making correct decisions based on practical safety issues. A case study in the application of the model is presented. The results show that the method is applicable and realistic with regard to the core of a coal mine's safety management. Consequently, the safe production of a mine and the awareness of advanced safe production management is accelerated.

A New Safety Assessment Method Based on Belief Rule Base With Attribute Reliability

Safety assessment is one of important aspects in health management.In safety assessment for practical systems,three problems exist:lack of observation information,high system complexity and environment interference.Belief rule base with attribute reliability(BRB-r)is an expert system that provides a useful way for dealing with these three problems.In BRB-r,once the input information is unreliable,the reliability of belief rule is influenced,which further influences the accuracy of its output belief degree.On the other hand,when many system characteristics exist,the belief rule combination will explode in BRB-r,and the BRB-r based safety assessment model becomes too complicated to be applied.Thus,in this paper,to balance the complexity and accuracy of the safety assessment model,a new safety assessment model based on BRB-r with considering belief rule reliability is developed for the first time.In the developed model,a new calculation method of the belief rule reliability is proposed with considering both attribute reliability and global ignorance.Moreover,to reduce the influence of uncertainty of expert knowledge,an optimization model for the developed safety assessment model is constructed.A case study of safety assessment of liquefied natural gas(LNG)storage tank is conducted to illustrate the effectiveness of the new developed model.

Safety assessment of platform loadout procedures based on unascertained measures

Safety assessment of offshore platforms is an urgent task. Such assessments are now focusing on the structure, maintenance, and retirement of a platform. Some methods employed have many shortcomings. For example, they cannot make the reliability adequately explicable. Therefore, a mathematical tool, the unascertained measure, was introduced. First, the basic knowledge of the unascertained sets was introduced briefly. Second, the unascertained measure was defined and credible identification was set up. The method has been introduced into the fields for safety assessment of a jacket loadout procedure. Engineering practices showed that it can complete the safety assessment systematically and scientifically without any assumption. The work should have significance in theory and practice for offshore engineering.

Calculation of Maximum Allowable Free Span Length and Safety Assessment of the DF1-1 Submarine Pipeline

The DFI-1 submarine pipeline was investigated using a dual-frequency side-scan sonar and a swath sounder system. More than a hundred scour pits under the pipeline were found, most of which have caused the span of the pipeline to increase and threatened its safety. The maximum allowable free span length （MAFSL） of the pipeline was determined through the limitations re- garding maximum allowable stress under static or quasi-static loads and the onset of Vortex Induced Vibrations （VIV） under different hydrodynamic actions. The results show that the MAFSL under static conditions is 56m. However, the MAFSLs are 30m and 20m under ordinary weather conditions and hurricane-induced currents for the 100-year return period, respectively, to avoid VIV as cal- culated by using the highest safety class factor. It is suggested that spanning pipelines longer than 20 m should be supported. Addi- tionally, eight successive spans which may also threaten the pipeline were proposed. The most hazardous scour pits are along the pipeline section from KP42 to KP51.

Risk management modeling and its application in maritime safety

Quantified risk assessment(QRA) needs mathematicization of risk theory.However,attention has been paid almost exclusively to applications of assessment methods,which has led to neglect of research into fundamental theories,such as the relationships among risk,safety,danger,and so on.In order to solve this problem,as a first step,fundamental theoretical relationships about risk and risk management were analyzed for this paper in the light of mathematics,and then illustrated with some charts.Second,man-machine-environment-management(MMEM) theory was introduced into risk theory to analyze some properties of risk.On the basis of this,a three-dimensional model of risk management was established that includes:a goal dimension;a management dimension;an operation dimension.This goal management operation(GMO) model was explained and then emphasis was laid on the discussion of the risk flowchart(operation dimension),which lays the groundwork for further study of risk management and qualitative and quantitative assessment.Next,the relationship between Formal Safety Assessment(FSA) and Risk Management was researched.This revealed that the FSA method,which the international maritime organization(IMO) is actively spreading,comes from Risk Management theory.Finally,conclusion were made about how to apply this risk management method to concrete fields efficiently and conveniently,as well as areas where further research is required.

Implications of safety requirements for the treatment of THMC processes in geological disposal systems for radioactive waste

The mission of nuclear safety authorities in national radioactive waste disposal programmes is to ensure that people and the environment are protected against the hazards of ionising radiations emitted by the waste.It implies the establishment of safety requirements and the oversight of the activities of the waste management organisation in charge of implementing the programme.In Belgium,the safety requirements for geological disposal rest on the following principles:defence-in-depth,demonstrability and the radiation protection principles elaborated by the International Commission on Radiological Protection(ICRP).Applying these principles requires notably an appropriate identification and characterisation of the processes upon which the safety functions fulfilled by the disposal system rely and of the processes that may affect the system performance.Therefore,research and development(R&D)on safety-relevant thermo-hydro-mechanical-chemical(THMC)issues is important to build confidence in the safety assessment.This paper points out the key THMC processes that might influence radionuclide transport in a disposal system and its surrounding environment,considering the dynamic nature of these processes.Their nature and significance are expected to change according to prevailing internal and external conditions,which evolve from the repository construction phase to the whole heatingecooling cycle of decaying waste after closure.As these processes have a potential impact on safety,it is essential to identify and to understand them properly when developing a disposal concept to ensure compliance with relevant safety requirements.In particular,the investigation of THMC processes is needed to manage uncertainties.This includes the identification and characterisation of uncertainties as well as for the understanding of their safety-relevance.R&D may also be necessary to reduce uncertainties of which the magnitude does not allow demonstrating the safety of the disposal system.

Formal Safety Assessment of a Marine Seismic Survey Vessel Operation,Incorporating Risk Matrix and Fault Tree Analysis

In maritime safety research,risk is assessed usually within the framework of formal safety assessment(FSA),which provides a formal and systematic methodology to improve the safety of lives,assets,and the environment.A bespoke application of FSA to mitigate accidents in marine seismic surveying is put forward in this paper,with the aim of improving the safety of seismic vessel operations,within the context of developing an economically viable strategy.The work herein takes a close look at the hazards in North Sea offshore seismic surveying,in order to identify critical risk factors,leading to marine seismic survey accidents.The risk factors leading to undesirable events are analysed both qualitatively and quantitatively.A risk matrix is introduced to screen the identified undesirable events.Further to the screening,Fault Tree Analysis(FTA)is presented to investigate and analyse the most critical risks of seismic survey operation,taking into account the lack of historical data.The obtained results show that man overboard(MOB)event is a major risk factor in marine seismic survey operation;lack of training on safe work practice,slippery deck as a result of rain,snow or water splash,sea state affecting human judgement,and poor communication are identified as the critical risk contributors to the MOB event.Consequently,the risk control options are focused on the critical risk contributors for decision-making.Lastly,suggestions for the introduction and development of the FSA methodology are highlighted for safer marine and offshore operations in general.

Analysis on evaluation ability of nonlinear safety assessment model of coal mines based on artificial neural network

Based on the integration analysis of goods and shortcomings of various methods used in safety assessment of coal mines, combining nonlinear feature of mine safety sub-system, this paper establishes the neural network assessment model of mine safety, analyzes the ability of artificial neural network to evaluate mine safety state, and lays the theoretical foundation of artificial neural network using in the systematic optimi- zation of mine safety assessment and getting reasonable accurate safety assessment result.

Safety Assessment for Autonomous Aerial Refueling Based on Reachability Analysis

Autonomous aerial refueling(AAR)has demonstrated significant benefits to aviation by extending the aircraft range and endurance.It is of significance to assess system safety for autonomous aerial refueling.In this paper,the reachability analysis method is adopted to assess system safety.Due to system uncertainties,the aerial refueling system can be considered as a stochastic system.Thus,probabilistic reachability is considered.Since there is a close relationship between reachability probability and collision probability,the collision probability of the AAR system is analyzed by using reachability analysis techniques.Then,the collision probability is accessed by using the Monte-Carlo experiment method.Finally,simulations demonstrate the effectiveness of the proposed safety assessment method.

Experimental Study on Permeability Characteristics of Geotubes for Seepage Analysis on Safety Assessment of Dams

Geotubes are heterogeneous structures composed of filling sand and bag material,and its pemeability characteristics are different from that of flling sand.The uncertainty of geotubes permeability characteristics results in the failure of seepage analysis of geotube dams,which restricts the safety assessment of the dams.As the basis of the study on the seepage mechanism of the geotubes,the influence of particle grading on pemeability cofficient of flling sand and sand covered with geotextiles were explored by the pemmeability tests of flling sand with different particle grading under the condition of sand covered with or without geotextiles.And the infuence of geotextiles on the permeability coefficient was analyzed by comparing permeability coefficient of sand covered with and without geotextiles.The test results show that the influence of single particle size content on permeability coe ficient is consistent under the condition of sand covered with and without geotextiles.The content of powder,fine,medium and coarse particles is linearly related to their respective permeability cofficients.And the content of powder,fine,medium particles is negatively correlated with their permeability coefficients,while the content of coarse particles is positively correlated with the permeability coefficient.But the pemeability coefficient of sand covered with geotextiles is smaller than that of flling sand under the same conditions.Finally,the parameter d2 50 Cc/Cu was selected as a variable representing the particle grading to fit the empirical formula of permeability coefficient of flling sand and sand covered with geotextiles.

Safety assessment of waste rock dump built on existing tailings ponds

The construction of waste rock dumps on existing tailing ponds has been put into practice in China to save precious land resources. This work focuses on the safety assessment of the Daheishan molybdenum mine waste rock dump under construction on two adjoining tailings ponds. The consolidation of the tailings foundation and the filling quality of the waste rock are investigated by the transient electromagnetic method through detecting water-rich areas and loose packing areas, from which, the depth of phreatic line is also estimated. With such information and the material parameters, the numerical method based on shear strength reduction is applied to analyzing the overall stability of the waste rock dump and the tailings ponds over a number of typical cross sections under both current and designed conditions, where the complex geological profiles exposed by site investigation are considered. Through numerical experiments, the influence of soft lenses in the tailings and possible loose packing areas in the waste rock is examined. Although large displacements may develop due to the soft tailings foundation, the results show that the waste rock dump satisfies the safety requirements under both present and designed conditions.