This research aims to examine the risk in the technology design of fast breeder reactors while the development depends on safety considerations. The project explored the variables, which could affect positively the ex...This research aims to examine the risk in the technology design of fast breeder reactors while the development depends on safety considerations. The project explored the variables, which could affect positively the expected average fuel burn-up, breeding ratio, and decay heat removal. That is accomplished using features such as guard vessels and elevated pipe routing to prevent the cracked state of both core components and fuel cladding interface conditions. So, the cracked region of fuel was detected by thermal-hydraulic analysis. We used ZrFeCr alloys to estimating of the rise in fuel cladding and coolant that can be incorporated in the design ZrFeCr alloys to uniform corrosion in temperature and 10.3 Mpa pressure. Fast creep of the reactor vessel during the coolant heat-up transient is another issue to be considered corrosion resistance of structural material can be achieved by controlling oxygen content in steel alloy. In this trend, S4337 S5140 steels are wide and can be used in future fossil power plants because of their excellent high-temperature strength.展开更多
In view of the need for geomechanical safety analysis of repositories in salt rock, failure criteria,creep rupture criteria,material models,pillar design methods and criteria for the assessment of barrier efficiency a...In view of the need for geomechanical safety analysis of repositories in salt rock, failure criteria,creep rupture criteria,material models,pillar design methods and criteria for the assessment of barrier efficiency as well as investigations of the interaction between hydraulics and mechanics for the case of uncontrolled flooded repositories are necessary. The introduction of damage mechanics and of the Hou/Lux material model including damages into geomechanical safety analysis of repositories in salt rock can reduce some previous deficits in knowledge and modelling. This article will be as a part of geotechnical assessment to introduce the Hou/Lux material model,a new concept of hydro-mechanical coupling and a pillar design method as well as criteria for the assessment of efficiency of geological barriers.展开更多
A Bayesian network approach is presented for probabilistic safety analysis(PSA)of railway lines.The idea consists of identifying and reproducing all the elements that the train encounters when circulating along a rail...A Bayesian network approach is presented for probabilistic safety analysis(PSA)of railway lines.The idea consists of identifying and reproducing all the elements that the train encounters when circulating along a railway line,such as light and speed limit signals,tunnel or viaduct entries or exits,cuttings and embankments,acoustic sounds received in the cabin,curves,etc.In addition,since the human error is very relevant for safety evaluation,the automatic train protection(ATP)systems and the driver behaviour and its time evolution are modelled and taken into account to determine the probabilities of human errors.The nodes of the Bayesian network,their links and the associated probability tables are automatically constructed based on the line data that need to be carefully given.The conditional probability tables are reproduced by closed formulas,which facilitate the modelling and the sensitivity analysis.A sorted list of the most dangerous elements in the line is obtained,which permits making decisions about the line safety and programming maintenance operations in order to optimize them and reduce the maintenance costs substantially.The proposed methodology is illustrated by its application to several cases that include real lines such as the Palencia-Santander and the Dublin-Belfast lines.展开更多
The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with ...The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.展开更多
In order to investigate safety character of solid propellant, the truing process was analyzed by a thermalmechanical coupled finite element method. Based on the viscoelastic integral constitutive relation, the tempera...In order to investigate safety character of solid propellant, the truing process was analyzed by a thermalmechanical coupled finite element method. Based on the viscoelastic integral constitutive relation, the temperature response in truing process was calculated. The result showed that the maximum temperature in solid propellant truing process could attain up to 65 ℃ when the truing velocity was 10 mm/s and the truing thickness was 1 mm, and there was no remarkable temperature change under the truing thickness of 1.0 mm, 1.5 mm and 2.5 mm. The hazard in truing process of solid propellant was mainly close to the edge of cutting area.展开更多
Traffic rule is a key factor affecting traffic flow and safety.We develop our models,including the cellular automata traffic flow model as well as the linear regression one,aiming at calculating traffic flow and evalu...Traffic rule is a key factor affecting traffic flow and safety.We develop our models,including the cellular automata traffic flow model as well as the linear regression one,aiming at calculating traffic flow and evaluating safety conditions with varied traffic rules.Then,we thoroughly investigate four types of paths in a freeway,namely two straight lanes,three straight lanes,ramps,and roundabouts as case studies and discuss the different traffic rules as comparison.The results demonstrate that"Keep-Right-Except-To-Pass"rule is not as effective as the free rule in promoting traffic flow;however,this rule ensures safety for drivers better than the free rule.Additionally,a new traffic rule,which sets different posted speed limits for adjacent lanes,is proposed to promote better traffic flow with safety requirements satisfied.Furthermore,we apply effective rules and alternatives,left driving norms as well as intelligent system as extension and obtain better results.Finally,model’s sensitivity analysis regarding to probability of decelerating and posted speed limits proves the stability of our results.展开更多
Based on the analytical solutions of T-H equations and its state transition matrix form,the open-loop control method of spacecraft impulsive relative hovering was studied,which is promising for practical engineering u...Based on the analytical solutions of T-H equations and its state transition matrix form,the open-loop control method of spacecraft impulsive relative hovering was studied,which is promising for practical engineering use.The true anomaly intervals of the hovering impulse were optimized by the nonlinear mathematical programming.Based on the calculation of collision probability,the method of safety analysis and risk management was proposed.The numerical simulations show that the introduced relative hovering method can be used for circular and elliptical reference orbits hovering.Furthermore,the local optimal solution can be obtained by applying the true anomaly intervals optimization method.The maximum collision probability and the minimum relative distance nearly appear at the same time.And,the smaller the relative distance is,the larger the collision probability.展开更多
The residual metal impurities in cisplatin, carboplatin and oxaliplatin were determined by ICP-AES. The samples were ignited and dissolved with HCl:HNO 3 (3:1). The method is simple and accurate. By the determination ...The residual metal impurities in cisplatin, carboplatin and oxaliplatin were determined by ICP-AES. The samples were ignited and dissolved with HCl:HNO 3 (3:1). The method is simple and accurate. By the determination of the metal residues in the samples, the calculated actual daily exposure and concentration of the metal Pd, Ir, Rh, Ru, Mo, Ni, Cr, V, Cu, Mn, Fe and Zn that were less than the permitted daily exposures (PDE) and the limited concentration permitted in the EMEA guideline on the specification limits for residues of metal catalysts or metal reagents [1] . The metal residues can de adequately removed from the active pharmaceutical ingredients and the corresponding drugs. The trace metal residues will not affect human health and lead to the safety hazard by the intravenous injection.展开更多
Safety Critical Systems (SCS) are those systems that may cause harm to the user(s) and/or the environment if operating outside of their prescribed specifications. Such systems are used in a wide variety of domains, su...Safety Critical Systems (SCS) are those systems that may cause harm to the user(s) and/or the environment if operating outside of their prescribed specifications. Such systems are used in a wide variety of domains, such as aerospace, automotive, railway transportation and healthcare. In this paper, we propose an approach to integrate safety analysis of SCSs within the Model Driven Engineering (MDE) system development process. The approach is based on model transformation and uses standard well-known techniques and open source tools for the modeling and analysis of SCSs. More specifically, the system modeled with the OMG’s standard systems modeling language, SysML, is automatically transformed in Fault Tree (FT) models, that can be analyzed with existing FT tools. The proposed model transformation takes place in two steps: a) generate FTs at the component level, in order to tackle complexity and enable reuse;and b) generate system level FTs by composing the components and their FTs. The approach is illustrated by applying it to a simplified industry-inspired case study.展开更多
The containment vessel of a nuclear power plant is the last barrier to prevent nuclear reactor radiation.Aseismic safety analysis is the key to appropriate containment vessel design.A prestressed concrete containment ...The containment vessel of a nuclear power plant is the last barrier to prevent nuclear reactor radiation.Aseismic safety analysis is the key to appropriate containment vessel design.A prestressed concrete containment vessel(PCCV) model with a semi-infinite elastic foundation and practical arrangement of tendons has been established to analyze the aseismic ability of the CPR1000 PCCV structure under seismic loads and internal pressure.A method to model the prestressing tendon and its interaction with concrete was proposed and the axial force of the prestressing tendons showed that the simulation was reasonable and accurate.The numerical results show that for the concrete structure, the location of the cylinder wall bottom around the equipment hatch and near the ring beam are critical locations with large principal stress.The concrete cracks occurred at the bottom of the PCCV cylinder wall under the peak earthquake motion of 0.50 g, however the PCCV was still basically in an elastic state.Furthermore, the concrete cracks occurred around the equipment hatch under the design internal pressure of 0.4MPa, but the steel liner was still in the elastic stage and its leak-proof function soundness was verified.The results provide the basis for analysis and design of containment vessels.展开更多
The safety performance of pedestrian and roadway dimensional-dividing buildings under seismic excitations are analysed.Considering the large displacement of the isolator bearing during earthquake,the gravity force bec...The safety performance of pedestrian and roadway dimensional-dividing buildings under seismic excitations are analysed.Considering the large displacement of the isolator bearing during earthquake,the gravity force becomes the dominant forces because of the accumulated permanent deformations in the building,which results in the structure collapse due to lateral instability.A model is established based on an inelastic time history analysis to consider P-Δ effects in multi-degree-of-freedom.A safety criterion of the system is defined.The influence of the stiffness of an independent column is revealed and compared with the influence of the shear force of the independent column to analyze the safety of the structures.Numerical results show that the special structure of pedestrian and roadway dimensional-dividing buildings can reduce the risk of the building in earthquake.The suitable section and height of the independent column greatly affect the building safety.展开更多
Pedestrian safety related to public bus transit is an integral part of promoting sustainability especially in the urban setting. This concept has received significant attention within the last decade as transit agenci...Pedestrian safety related to public bus transit is an integral part of promoting sustainability especially in the urban setting. This concept has received significant attention within the last decade as transit agencies strive to make their systems more sustainable and safer at the same time. This study examined pedestrian collisions related to public transit buses in Philadelphia over a three-year study period from 2008 to 2011. The objective is to perform a detailed analysis on crash records, which provides the foundation on statistics for bus-pedestrian collision to allow for future studies in modeling work in this field. Results of this research provided insights on bus-pedestrian collisions in terms of bus maneuver, cause of crash, impact point of bus, and relation to hourly traffic volume. A strong correlation was found between traffic volume and bus-pedestrian collision rate in terms of hours of the day. For any given hour, an increase in collision frequency was found if the traffic volume exceeds a threshold of 5% of its average annual daily traffic. This serves as an indicator of locations that pedestrians are vulnerable at. Analyses were conducted to the fullest extent allowable by the limited dataset. This study presents findings that can be future developed and investigated in future studies. Additionally, countermeasures are recommended in each section that presents a critical area to address.展开更多
Aiming at the mooring stability of the ship⁃borne vehicles and the safety of steel chain links under high sea condition,the rigid⁃flexible coupling dynamics model of deck⁃vehicle⁃mooring chain was established,the load...Aiming at the mooring stability of the ship⁃borne vehicles and the safety of steel chain links under high sea condition,the rigid⁃flexible coupling dynamics model of deck⁃vehicle⁃mooring chain was established,the load characteristics of the mooring chain under class⁃9 sea state were obtained.The failure mode of the chain link and the influence law of the torsion angle on the stress distribution was obtained.Based on Miner's linear cumulative damage theory,the fatigue life of the mooring chain link was analyzed using the corrected mooring link S-N curve.The existing safety hazards were pointed out.The optimization of the mooring scheme was proposed.The conclusions are as follows:1)The mooring scheme can meet the mooring stability requirements of vehicles under high sea condition.2)The failure mode on the outside of the link crown was mainly tensile failure,and the failure mode on the inside is mainly contact fatigue failure under compression.3)The torsion angle had a significant effect on the stress situation of the chain link.When it exceeds 15 degrees,it will no longer meet the strength requirements.4)Through the optimization of the mooring scheme,the fatigue life of the steel chain link has been significantly increased.展开更多
This paper constructed the mine ventilation network model using the powerful function of attribute management and display of GIS based on the study of GIS and mine ventilation network. In a mine ventilation network, a...This paper constructed the mine ventilation network model using the powerful function of attribute management and display of GIS based on the study of GIS and mine ventilation network. In a mine ventilation network, a specified result can be obtained by defining weight values for attribute fields as the constraint condition. It is of great importance for mines to determine the best rescue and leaving route by the analyses of mine ventilation network routes, nodes and loops when a mine accident happens.展开更多
Access to security and safe food is a basic human necessity and essential for a sustainable world. To perform hi-end food safety analysis and risk assessment with state of the art technologies is of utmost importance ...Access to security and safe food is a basic human necessity and essential for a sustainable world. To perform hi-end food safety analysis and risk assessment with state of the art technologies is of utmost importance thereof. With applications as exemplified by microfluidic immunoassay,aptasensor,direct analysis in real time,high resolution mass spectrometry,benchmark dose and chemical specific adjustment factor,this review presents frontier food safety analysis and risk assessment technologies,from which both food quality and public health will benefit undoubtedly in a foreseeable future.展开更多
Causality Diagram (CD) is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper...Causality Diagram (CD) is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper, and the Minimal Cut Set, the Minimal Path Set and the Importance were introduced to develop the methodology. These concepts are employed to analyze the influence each event has on the top event ? the gas explosion, so as to find out about the defects of the system and accordingly help to work out the emphasis of the precautionary work and some preventive measures as well. The results of the safety analysis are in accordance with the practical requirements; therefore the preventive measures are certain to work effectively. In brief, according to the research CD is so effective in the safety analysis and the safety assessment that it can be a qualitative and quantitative method to predict the accident as well as offer some effective measures for the investigation, the prevention and the control of the accident.展开更多
The research on the present situation of soil and water development and utilization in Shiyang River Basin shows that water resources and eco-environment situation in this area are near the edge of collapse. Since the...The research on the present situation of soil and water development and utilization in Shiyang River Basin shows that water resources and eco-environment situation in this area are near the edge of collapse. Since the water crises occurred in the 1970s, problems caused by continuous decrease of water resources have been becoming serious year by year and eco-environment crisis occurred as a consequence. Up to now, 10 380ha of irrigated lands have been abandoned due to sand coverage and water shortage in the basin. Ground water was over exploded in Wuwei and Minqin because of water shortage. Ground water table in many places dropped under 5m (which is the ecology water table level), thus about 3000ha of Elaeagnus angustifolia forest come to dead and another 5800ha become feeble, and wind-drift sand near the oasis become alive. According to the current situation, if water utilization scope was not enlarged, a water transfer volume of 600×106m3/a from other areas will be suitable to keep water resources and eco-environment safety in the basin, and also 70×106m3/a will be left as spare water. Under this condition the water resources and eco-environment of the basin can reach the critical safety line of 2.032×109m3/a; or if 180×106m3 of water can be transferred from other areas, the water resources can reach the safety warning line of 1.732×109m3/a.展开更多
文摘This research aims to examine the risk in the technology design of fast breeder reactors while the development depends on safety considerations. The project explored the variables, which could affect positively the expected average fuel burn-up, breeding ratio, and decay heat removal. That is accomplished using features such as guard vessels and elevated pipe routing to prevent the cracked state of both core components and fuel cladding interface conditions. So, the cracked region of fuel was detected by thermal-hydraulic analysis. We used ZrFeCr alloys to estimating of the rise in fuel cladding and coolant that can be incorporated in the design ZrFeCr alloys to uniform corrosion in temperature and 10.3 Mpa pressure. Fast creep of the reactor vessel during the coolant heat-up transient is another issue to be considered corrosion resistance of structural material can be achieved by controlling oxygen content in steel alloy. In this trend, S4337 S5140 steels are wide and can be used in future fossil power plants because of their excellent high-temperature strength.
文摘In view of the need for geomechanical safety analysis of repositories in salt rock, failure criteria,creep rupture criteria,material models,pillar design methods and criteria for the assessment of barrier efficiency as well as investigations of the interaction between hydraulics and mechanics for the case of uncontrolled flooded repositories are necessary. The introduction of damage mechanics and of the Hou/Lux material model including damages into geomechanical safety analysis of repositories in salt rock can reduce some previous deficits in knowledge and modelling. This article will be as a part of geotechnical assessment to introduce the Hou/Lux material model,a new concept of hydro-mechanical coupling and a pillar design method as well as criteria for the assessment of efficiency of geological barriers.
文摘A Bayesian network approach is presented for probabilistic safety analysis(PSA)of railway lines.The idea consists of identifying and reproducing all the elements that the train encounters when circulating along a railway line,such as light and speed limit signals,tunnel or viaduct entries or exits,cuttings and embankments,acoustic sounds received in the cabin,curves,etc.In addition,since the human error is very relevant for safety evaluation,the automatic train protection(ATP)systems and the driver behaviour and its time evolution are modelled and taken into account to determine the probabilities of human errors.The nodes of the Bayesian network,their links and the associated probability tables are automatically constructed based on the line data that need to be carefully given.The conditional probability tables are reproduced by closed formulas,which facilitate the modelling and the sensitivity analysis.A sorted list of the most dangerous elements in the line is obtained,which permits making decisions about the line safety and programming maintenance operations in order to optimize them and reduce the maintenance costs substantially.The proposed methodology is illustrated by its application to several cases that include real lines such as the Palencia-Santander and the Dublin-Belfast lines.
文摘The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.
文摘In order to investigate safety character of solid propellant, the truing process was analyzed by a thermalmechanical coupled finite element method. Based on the viscoelastic integral constitutive relation, the temperature response in truing process was calculated. The result showed that the maximum temperature in solid propellant truing process could attain up to 65 ℃ when the truing velocity was 10 mm/s and the truing thickness was 1 mm, and there was no remarkable temperature change under the truing thickness of 1.0 mm, 1.5 mm and 2.5 mm. The hazard in truing process of solid propellant was mainly close to the edge of cutting area.
基金the support of Wuhan Transport and Communications Committee (WHJT-CZH-2016-1C178)
文摘Traffic rule is a key factor affecting traffic flow and safety.We develop our models,including the cellular automata traffic flow model as well as the linear regression one,aiming at calculating traffic flow and evaluating safety conditions with varied traffic rules.Then,we thoroughly investigate four types of paths in a freeway,namely two straight lanes,three straight lanes,ramps,and roundabouts as case studies and discuss the different traffic rules as comparison.The results demonstrate that"Keep-Right-Except-To-Pass"rule is not as effective as the free rule in promoting traffic flow;however,this rule ensures safety for drivers better than the free rule.Additionally,a new traffic rule,which sets different posted speed limits for adjacent lanes,is proposed to promote better traffic flow with safety requirements satisfied.Furthermore,we apply effective rules and alternatives,left driving norms as well as intelligent system as extension and obtain better results.Finally,model’s sensitivity analysis regarding to probability of decelerating and posted speed limits proves the stability of our results.
文摘Based on the analytical solutions of T-H equations and its state transition matrix form,the open-loop control method of spacecraft impulsive relative hovering was studied,which is promising for practical engineering use.The true anomaly intervals of the hovering impulse were optimized by the nonlinear mathematical programming.Based on the calculation of collision probability,the method of safety analysis and risk management was proposed.The numerical simulations show that the introduced relative hovering method can be used for circular and elliptical reference orbits hovering.Furthermore,the local optimal solution can be obtained by applying the true anomaly intervals optimization method.The maximum collision probability and the minimum relative distance nearly appear at the same time.And,the smaller the relative distance is,the larger the collision probability.
基金The national SME technology innovation fund(11C26215305898)Kunming SME technology innovation fund(CJ2011040)
文摘The residual metal impurities in cisplatin, carboplatin and oxaliplatin were determined by ICP-AES. The samples were ignited and dissolved with HCl:HNO 3 (3:1). The method is simple and accurate. By the determination of the metal residues in the samples, the calculated actual daily exposure and concentration of the metal Pd, Ir, Rh, Ru, Mo, Ni, Cr, V, Cu, Mn, Fe and Zn that were less than the permitted daily exposures (PDE) and the limited concentration permitted in the EMEA guideline on the specification limits for residues of metal catalysts or metal reagents [1] . The metal residues can de adequately removed from the active pharmaceutical ingredients and the corresponding drugs. The trace metal residues will not affect human health and lead to the safety hazard by the intravenous injection.
文摘Safety Critical Systems (SCS) are those systems that may cause harm to the user(s) and/or the environment if operating outside of their prescribed specifications. Such systems are used in a wide variety of domains, such as aerospace, automotive, railway transportation and healthcare. In this paper, we propose an approach to integrate safety analysis of SCSs within the Model Driven Engineering (MDE) system development process. The approach is based on model transformation and uses standard well-known techniques and open source tools for the modeling and analysis of SCSs. More specifically, the system modeled with the OMG’s standard systems modeling language, SysML, is automatically transformed in Fault Tree (FT) models, that can be analyzed with existing FT tools. The proposed model transformation takes place in two steps: a) generate FTs at the component level, in order to tackle complexity and enable reuse;and b) generate system level FTs by composing the components and their FTs. The approach is illustrated by applying it to a simplified industry-inspired case study.
基金National Natural Science Foundation of China under Grant Nos.51138001 and 51479027
文摘The containment vessel of a nuclear power plant is the last barrier to prevent nuclear reactor radiation.Aseismic safety analysis is the key to appropriate containment vessel design.A prestressed concrete containment vessel(PCCV) model with a semi-infinite elastic foundation and practical arrangement of tendons has been established to analyze the aseismic ability of the CPR1000 PCCV structure under seismic loads and internal pressure.A method to model the prestressing tendon and its interaction with concrete was proposed and the axial force of the prestressing tendons showed that the simulation was reasonable and accurate.The numerical results show that for the concrete structure, the location of the cylinder wall bottom around the equipment hatch and near the ring beam are critical locations with large principal stress.The concrete cracks occurred at the bottom of the PCCV cylinder wall under the peak earthquake motion of 0.50 g, however the PCCV was still basically in an elastic state.Furthermore, the concrete cracks occurred around the equipment hatch under the design internal pressure of 0.4MPa, but the steel liner was still in the elastic stage and its leak-proof function soundness was verified.The results provide the basis for analysis and design of containment vessels.
基金Supported by the Science Foundation of Gansu(2008GS00563)the Research Foundation of LUT(X1014XC034)
文摘The safety performance of pedestrian and roadway dimensional-dividing buildings under seismic excitations are analysed.Considering the large displacement of the isolator bearing during earthquake,the gravity force becomes the dominant forces because of the accumulated permanent deformations in the building,which results in the structure collapse due to lateral instability.A model is established based on an inelastic time history analysis to consider P-Δ effects in multi-degree-of-freedom.A safety criterion of the system is defined.The influence of the stiffness of an independent column is revealed and compared with the influence of the shear force of the independent column to analyze the safety of the structures.Numerical results show that the special structure of pedestrian and roadway dimensional-dividing buildings can reduce the risk of the building in earthquake.The suitable section and height of the independent column greatly affect the building safety.
文摘Pedestrian safety related to public bus transit is an integral part of promoting sustainability especially in the urban setting. This concept has received significant attention within the last decade as transit agencies strive to make their systems more sustainable and safer at the same time. This study examined pedestrian collisions related to public transit buses in Philadelphia over a three-year study period from 2008 to 2011. The objective is to perform a detailed analysis on crash records, which provides the foundation on statistics for bus-pedestrian collision to allow for future studies in modeling work in this field. Results of this research provided insights on bus-pedestrian collisions in terms of bus maneuver, cause of crash, impact point of bus, and relation to hourly traffic volume. A strong correlation was found between traffic volume and bus-pedestrian collision rate in terms of hours of the day. For any given hour, an increase in collision frequency was found if the traffic volume exceeds a threshold of 5% of its average annual daily traffic. This serves as an indicator of locations that pedestrians are vulnerable at. Analyses were conducted to the fullest extent allowable by the limited dataset. This study presents findings that can be future developed and investigated in future studies. Additionally, countermeasures are recommended in each section that presents a critical area to address.
文摘Aiming at the mooring stability of the ship⁃borne vehicles and the safety of steel chain links under high sea condition,the rigid⁃flexible coupling dynamics model of deck⁃vehicle⁃mooring chain was established,the load characteristics of the mooring chain under class⁃9 sea state were obtained.The failure mode of the chain link and the influence law of the torsion angle on the stress distribution was obtained.Based on Miner's linear cumulative damage theory,the fatigue life of the mooring chain link was analyzed using the corrected mooring link S-N curve.The existing safety hazards were pointed out.The optimization of the mooring scheme was proposed.The conclusions are as follows:1)The mooring scheme can meet the mooring stability requirements of vehicles under high sea condition.2)The failure mode on the outside of the link crown was mainly tensile failure,and the failure mode on the inside is mainly contact fatigue failure under compression.3)The torsion angle had a significant effect on the stress situation of the chain link.When it exceeds 15 degrees,it will no longer meet the strength requirements.4)Through the optimization of the mooring scheme,the fatigue life of the steel chain link has been significantly increased.
文摘This paper constructed the mine ventilation network model using the powerful function of attribute management and display of GIS based on the study of GIS and mine ventilation network. In a mine ventilation network, a specified result can be obtained by defining weight values for attribute fields as the constraint condition. It is of great importance for mines to determine the best rescue and leaving route by the analyses of mine ventilation network routes, nodes and loops when a mine accident happens.
基金financially supported by the Beijing Municipal Science and Technology Project, China (Z131110000613066)the Educational and Teaching Reform Project for Graduate Students, China (G-JG-XJ201408)the Beijing Key Laboratory of Bioprocess, China
文摘Access to security and safe food is a basic human necessity and essential for a sustainable world. To perform hi-end food safety analysis and risk assessment with state of the art technologies is of utmost importance thereof. With applications as exemplified by microfluidic immunoassay,aptasensor,direct analysis in real time,high resolution mass spectrometry,benchmark dose and chemical specific adjustment factor,this review presents frontier food safety analysis and risk assessment technologies,from which both food quality and public health will benefit undoubtedly in a foreseeable future.
基金Supported by the Natural Science Foundation of China (No. 59677009) the National Research Foundation for the Doctoral Program of Higher Education of China (No.99061116)
文摘Causality Diagram (CD) is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper, and the Minimal Cut Set, the Minimal Path Set and the Importance were introduced to develop the methodology. These concepts are employed to analyze the influence each event has on the top event ? the gas explosion, so as to find out about the defects of the system and accordingly help to work out the emphasis of the precautionary work and some preventive measures as well. The results of the safety analysis are in accordance with the practical requirements; therefore the preventive measures are certain to work effectively. In brief, according to the research CD is so effective in the safety analysis and the safety assessment that it can be a qualitative and quantitative method to predict the accident as well as offer some effective measures for the investigation, the prevention and the control of the accident.
文摘The research on the present situation of soil and water development and utilization in Shiyang River Basin shows that water resources and eco-environment situation in this area are near the edge of collapse. Since the water crises occurred in the 1970s, problems caused by continuous decrease of water resources have been becoming serious year by year and eco-environment crisis occurred as a consequence. Up to now, 10 380ha of irrigated lands have been abandoned due to sand coverage and water shortage in the basin. Ground water was over exploded in Wuwei and Minqin because of water shortage. Ground water table in many places dropped under 5m (which is the ecology water table level), thus about 3000ha of Elaeagnus angustifolia forest come to dead and another 5800ha become feeble, and wind-drift sand near the oasis become alive. According to the current situation, if water utilization scope was not enlarged, a water transfer volume of 600×106m3/a from other areas will be suitable to keep water resources and eco-environment safety in the basin, and also 70×106m3/a will be left as spare water. Under this condition the water resources and eco-environment of the basin can reach the critical safety line of 2.032×109m3/a; or if 180×106m3 of water can be transferred from other areas, the water resources can reach the safety warning line of 1.732×109m3/a.
