To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains i...To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains in a subcritical state during routine,normal,and accidental transport conditions.In the event of an accident,the rods within the storage tank may become rearranged,introducing uncertainty that must be accounted for to ensure that criticality analysis results are conservative.Historically,this uncertainty was addressed overly conservatively due to limited research on non-uniform arrangement scenarios,which proved unsuitable for criticality safety analysis of spent fuel packages.This paper introduced three distinct methods to non-uniformly rearrange fuel rods—Uniform Arrangement by Blocks,Layer-by-Layer Determination,and Birdcage Deformation—and meticulously evaluates the influences of rod rearrangement on the effective multiplication factor of neutrons,k eff,utilizing the Monte Carlo method.Ultimately,this study presents a holistic method capable of encompassing the entire spectrum of potential effects stemming from the rearrangement of fuel rods during rods mispositioning accident.By augmenting the safety margin,this approach proves to be adeptly suited for the criticality safety analysis of nuclear fuel transport containers.展开更多
The ability to assess the reliability of safety-critical systems is one of the most crucial requirements in the design of modern safety-critical systems where even a minor failure can result in loss of life or irrepar...The ability to assess the reliability of safety-critical systems is one of the most crucial requirements in the design of modern safety-critical systems where even a minor failure can result in loss of life or irreparable damage to the environment.Model checking is an automatic technique that verifies or refutes system properties by exploring all reachable states(state space)of a model.In large and complex systems,it is probable that the state space explosion problem occurs.In exploring the state space of systems modeled by graph transformations,the rule applied on the current state specifies the rule that can perform on the next state.In other words,the allowed rule on the current state depends only on the applied rule on the previous state,not the ones on earlier states.This fact motivates us to use a Markov chain(MC)to capture this type of dependencies and applies the Estimation of Distribution Algorithm(EDA)to improve the quality of the MC.EDA is an evolutionary algorithm directing the search for the optimal solution by learning and sampling probabilistic models through the best individuals of a population at each generation.To show the effectiveness of the proposed approach,we implement it in GROOVE,an open source toolset for designing and model checking graph transformation systems.Experimental results confirm that the proposed approach has a high speed and accuracy in comparison with the existing meta-heuristic and evolutionary techniques in safety analysis of systems specified formally through graph transformations.展开更多
Objective To analyze the current research status and development trend of active surveillance of drug safety in China,and to provide reference and suggestions for future research.Methods Using bibliometric methods and...Objective To analyze the current research status and development trend of active surveillance of drug safety in China,and to provide reference and suggestions for future research.Methods Using bibliometric methods and with the help of the CiteSpace 6.1.R6,the literature on active surveillance of drug safety in CNKI from 2010 to 2022 was visualized and analyzed in terms of authors,institutions and keywords.Results and Conclusion The research on active surveillance of drug safety in China started late and is in a stable development period.Some Chinese scholars have done more work on active surveillance of drug safety.Additionally,a number of institutions have published some articles and surveillance objects,surveillance methods,and surveillance results are the main research content.However,the cross-institutional cooperation is not close.The traditional Chinese medicine injection,centralized surveillance,and automatic surveillance are the hot spots of research.It is the latest research frontier to use the Chinese hospital pharmacovigilance system to actively monitor drug safety.At present,the research related to active surveillance of drug safety in China is still in the early stage,and more in-depth research is needed to follow up.展开更多
In order to analysis the oxygen distribution in the adsorption bed during the hydrogen purification process from oxygen-containing feed gas and the safety of device operation, this article established a non-isothermal...In order to analysis the oxygen distribution in the adsorption bed during the hydrogen purification process from oxygen-containing feed gas and the safety of device operation, this article established a non-isothermal model for the pressure swing adsorption (PSA) separation process of 4-component (H_(2)/O_(2)/N_(2)/CH_(4)), and adopted a composite adsorption bed of activated carbon and molecular sieve. In this article, the oxygen distribution in the adsorption bed under different feed gas oxygen contents, different adsorption pressures, and different product hydrogen purity was studied for both vacuuming process and purging process. The study shows that during the process from the end of adsorption to the end of providing purging, the peak value of oxygen concentration in the adsorption bed gradually increases, with the highest value exceeding 30 times the oxygen content of the feed gas. Moreover, the concentration multiplier of oxygen in the adsorption bed increases with the increase of the adsorption pressure, decreases with the increase of the oxygen content in the feed gas, and increases with the decrease of the hydrogen product purity. When the oxygen content in the feed gas reaches 0.3% (vol), the peak value of oxygen concentration in the adsorption bed exceeds 10% (vol), which will make the front part of the oxygen concentration peak fall in an explosion limit range. As the decrease of product hydrogen content, the oxygen concentration peak in the adsorption bed will gradually move forward to the adsorption bed outlet, and even penetrate through the adsorption bed. And during the process of the oxygen concentration peak moving forward, the oxygen will enter the pipeline at the outlet of the adsorption bed, which will make the pipeline space of high-speed gas flow into an explosion range, bringing great risk to the device. The preferred option for safe operation of PSA for hydrogen purification from oxygen-containing feed gas is to deoxygenate the feed gas. When deoxygenation is not available, a lower adsorption pressure and a higher product hydrogen purity (greater than or equal to 99.9% (vol)) can be used to avoid the gas in the adsorption bed outlet pipeline being in the explosion range.展开更多
Objective: To examine the daily life care, spiritual comfort, and fall safety care needs of the elderly in urban and rural areas of Tangshan, along with their influencing factors. Methods: From August 2022 to April 20...Objective: To examine the daily life care, spiritual comfort, and fall safety care needs of the elderly in urban and rural areas of Tangshan, along with their influencing factors. Methods: From August 2022 to April 2023, an investigation was conducted among urban and rural elderly individuals aged over 75 years in Tangshan City using the Activities of Daily Living Scale, the Revised Community Elderly Fall Risk Assessment Tool, and the Loneliness Scale. Results: The study included 750 urban and 740 rural elderly individuals aged over 75 years. Matrix analysis revealed a significant proportion of fall safety care needs across various daily life and spiritual care requirements. Multiple factor analysis indicated that advanced age, lower education levels, a greater number of chronic diseases, and lower levels of family and social support were associated with higher care demands among the elderly in both urban and rural areas. These differences were statistically significant (P < 0.05). Conclusion: The elderly in urban and rural areas demonstrate a high demand for fall safety care. Particular attention should be given to individuals with lower education levels, those who are widowed, those with multiple chronic diseases, and those with low levels of family and social support to better meet the diverse care needs of this population.展开更多
An improved safety analysis based on the causality diagram for the complex system of micro aero-engines is presented.The study is examined by using the causality diagram in analytical failure cases due to rupture or p...An improved safety analysis based on the causality diagram for the complex system of micro aero-engines is presented.The study is examined by using the causality diagram in analytical failure cases due to rupture or pentration in the receiver of micro turbojet engine casing,and the comparisons are also made with the results from the traditional fault tree analysis.Experimental results show two main advantages：（1）Quantitative analysis which is more reliable for the failure analysis in jet engines can be produced by the causality diagram analysis;（2）Graphical representation of causality diagram is easier to apply in real test cases and more effective for the safety assessment.展开更多
This paper presents an application of global sensitivity analysis for system safety analysis of reciprocating aircraft engine. Compared with local sensitivity analysis results, global sensitivity analysis could provid...This paper presents an application of global sensitivity analysis for system safety analysis of reciprocating aircraft engine. Compared with local sensitivity analysis results, global sensitivity analysis could provide more information on parameter inter- actions, which are significant in complex system safety analysis. First, a deterministic aviation reciprocating engine thermody- namics model is developed and parameters of interest are defined as random variables. Then, samples are generated by Monte Carlo method for the parameters used in engine model on the basis of definition of factor distribution. Eventually, results from engine model are generated and importance indices are calculated. Based on the analysis results, design is improved to satisfy the airworthiness requirements. The results reveal that by using global sensitivity analysis, the parameters could be ranked with respect to their importance, including first order indices and total sensitivity indices. By reducing the uncertainty of parameters and adjusting the range of inputs, safety criteria would be satisfied.展开更多
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...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.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
According to the ecological safety evaluation index data of land-use change in Ji'an City from 1999 to 2008,positive treatment on selected reverse indices is conducted by Reciprocal Method.Meanwhile,Index Method i...According to the ecological safety evaluation index data of land-use change in Ji'an City from 1999 to 2008,positive treatment on selected reverse indices is conducted by Reciprocal Method.Meanwhile,Index Method is used to standardize the selected indices,and Principal Component Analysis is applied by using year as a unit.FB is obtained,which is related with the ecological safety of land-use change from 1999 to 2008.According to the scientific,integrative,hierarchical,practical and dynamic principles,ecological safety evaluation index system of land-use change in Ji'an City is established.Principal Component Analysis and evaluation model are used to calculate four parameters,including the natural resources safety index of land use,the socio-economic safety indicators of land use,the eco-environmental safety index of land use,and the ecological safety degree of land use in Ji'an City.Result indicates that the ecological safety degree of land use in Ji'an City shows a slow upward trend as a whole.At the same time,ecological safety degree of land-use change is relatively low in Ji'an City with the safety value of 0.645,which is at a weak safety zone and needs further monitoring and maintenance.展开更多
As longwall caving mining method prevails rapidly in China coal mines, amount of gas emission from longwall faces and goaf area increased significantly. Using traditional gas drainage methods, such as drilling upward ...As longwall caving mining method prevails rapidly in China coal mines, amount of gas emission from longwall faces and goaf area increased significantly. Using traditional gas drainage methods, such as drilling upward holes to roof strata in tailgate or drilling inseam and cross-measure boreholes, could not meet methane drainage requirements in a gassy mine. The alternative is to drill boreholes from surface down to the Iongwall goaf area to drain the gas out. As soon as a coal seam is extracted out, the upper rock strata above the goaf start to collapse or become fractured depending upon the rock characteristics and the height above the coal seam. During overlying rock strata being fractured, boreholes in the area may be damaged due to ground movement after the passage of the Iongwall face. The sudden damage of a borehole may cause a Iongwall production halt or even a serious mine accident. A theoretical calculation of the stability of surface boreholes in mining affected area is introduced along with an example of determination of borehole and casing diameters is given for demonstration. By using this method for the drilling design, the damage of surface boreholes caused by excessive mining induced displacement can be effectively reduced if not totally avoided. Borehole and casing diameters as well as characteristics of filling materials can be determined using the proposed method by calculating the horizontal movement and vertical stain at different borehole depths.展开更多
In recent years improper allocation of safety input has prevailed in coal mines in China, which resulted in the frequent accidents in coal mining operation. A comprehensive assessment of the input efficiency of coal m...In recent years improper allocation of safety input has prevailed in coal mines in China, which resulted in the frequent accidents in coal mining operation. A comprehensive assessment of the input efficiency of coal mine safety should lead to improved efficiency in the use of funds and management resources. This helps government and enterprise managers better understand how safety inputs are used and to optimize allocation of resources. Study on coal mine＇s efficiency assessment of safety input was con- ducted in this paper. A C^2R model with non-Archimedean infinitesimal vector based on output is established after consideration of the input characteristics and the model properties. An assessment of an operating mine was done using a specific set of input and output criteria. It is found that the safety input was efficient in 2002 and 2005 and was weakly efficient in 2003. However, the efficiency was relatively low in both 2001 and 2004. The safety input resources can be optimized and adjusted by means of projection theory. Such analysis shows that, on average in 2001 and 2004, 45% of the expended funds could have been saved. Likewise, 10% of the safety management and technical staff could have been eliminated and working hours devoted to safety could have been reduced by 12%. These conditions could have Riven the same results.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 rood 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 rood safety analysis and risk assessment with state of the art technologies is of utmost importance thereof. With applications as exemplified by microfiuidic 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
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
Safety monitoring and stability analysis of high slopes are important for high dam construction in high mountainous regions or precipitous gorges. In this paper, deformation characteristics of toppling block at upper ...Safety monitoring and stability analysis of high slopes are important for high dam construction in high mountainous regions or precipitous gorges. In this paper, deformation characteristics of toppling block at upper abutment, deforming tensile rip wedge in the middle part and deep fractures are comprehensively analyzed based on the geological conditions, construction methods and monitoring results of left abutment slope in Jinping Ⅰ hydropower station. Safety analyses of surface and shallow-buried rock masses and the corresponding anchorage system are presented. The monitoring results indicate that the global stability of the large wedge block in the left abutment is effectively under control, and the abutment slope is stable in a global sense. After the completion of excavation, the deformations of toppling block at the top of the slope and deep fracture zone continue at a very low rate, which can be explained as 'rock mass creep'. Further monitoring and analysis are needed.展开更多
A systematic safety analysis method is presented to guide the whole analysis process starting with safety analysis requirement and ending with technical and economical evaluation of the knowledge model and the arrange...A systematic safety analysis method is presented to guide the whole analysis process starting with safety analysis requirement and ending with technical and economical evaluation of the knowledge model and the arrangement of sensors. The method consists of five phases, including data acquisition on factual evidence and collecting design, manufacturing, and installation data of equipment; establishing knowledge model; measurable analysis and selection of sensors as well cost evaluation; knowledge description; and overall evaluation. The proposed method is used for safety analysis of hydraulic power generating units and the analysis results validate the method very well.展开更多
Abstract： 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...Abstract： 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
In order to ensure the safety of engine life limited parts （ELLP） according to airworthiness regulations, a numerical approach integrating one-way fluid structure interaction （FSI） and probabilistic risk assessme...In order to ensure the safety of engine life limited parts （ELLP） according to airworthiness regulations, a numerical approach integrating one-way fluid structure interaction （FSI） and probabilistic risk assessment （PRA） is developed, by which the variation of flow parameters in a rotor-stator cavity on the safety of gas turbine disks is investigated. The results indicate that the flow parameters affect the probability of fracture of a gas turbine disk since they can change the distribution of stress and temperature of the disk. The failure probability of the disk rises with increasing rotation Reynolds number and Chebyshev number, but descends with increasing inlet Reynolds number. In addition, a sampling based sensitivity analysis with finite difference method is conducted to determine the sensitivities of the safety with respect to the flow parameters. The sensitivity estimates show that the rotation Reynolds number is the dominant variable in safety analysis of a rotor-stator cavity among the flow parameters.展开更多
With the continuous advancement of the avionics system,crew members are correspondingly reduced,and Single Pilot Operations(SPO)has attracted widespread attention from scholars.To meet the flight requirements in SPO m...With the continuous advancement of the avionics system,crew members are correspondingly reduced,and Single Pilot Operations(SPO)has attracted widespread attention from scholars.To meet the flight requirements in SPO mode,it is necessary to further strengthen air-ground coordination system integration,but at the same time,there will be some safety issues caused by resource integration,function fusion,and task synthesis.Aimed at the safety problems caused by task synthesis,an efficient differential bicluster mining algorithm--DFCluster algorithm is proposed in this paper to discover potential hazardous elements or propagation mechanisms through mining the resource-function matrixes.To mine efficiently,several pruning techniques are designed for generating maximal biclusters without candidate maintenance.The experimental results show that the DFCluster algorithm is more efficient than the existing differential biclustering algorithms under different scales of artificial datasets and public datasets.Then,a typical flight scenario is designed based on SPO air-ground collaborative system architecture,and combined with our proposed DFCluster algorithm for task synthesis safety analysis.Based on the mining results,the SPO airground collaborative system architecture is modified,which ultimately improves the safety of the SPO system.展开更多
文摘To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains in a subcritical state during routine,normal,and accidental transport conditions.In the event of an accident,the rods within the storage tank may become rearranged,introducing uncertainty that must be accounted for to ensure that criticality analysis results are conservative.Historically,this uncertainty was addressed overly conservatively due to limited research on non-uniform arrangement scenarios,which proved unsuitable for criticality safety analysis of spent fuel packages.This paper introduced three distinct methods to non-uniformly rearrange fuel rods—Uniform Arrangement by Blocks,Layer-by-Layer Determination,and Birdcage Deformation—and meticulously evaluates the influences of rod rearrangement on the effective multiplication factor of neutrons,k eff,utilizing the Monte Carlo method.Ultimately,this study presents a holistic method capable of encompassing the entire spectrum of potential effects stemming from the rearrangement of fuel rods during rods mispositioning accident.By augmenting the safety margin,this approach proves to be adeptly suited for the criticality safety analysis of nuclear fuel transport containers.
文摘The ability to assess the reliability of safety-critical systems is one of the most crucial requirements in the design of modern safety-critical systems where even a minor failure can result in loss of life or irreparable damage to the environment.Model checking is an automatic technique that verifies or refutes system properties by exploring all reachable states(state space)of a model.In large and complex systems,it is probable that the state space explosion problem occurs.In exploring the state space of systems modeled by graph transformations,the rule applied on the current state specifies the rule that can perform on the next state.In other words,the allowed rule on the current state depends only on the applied rule on the previous state,not the ones on earlier states.This fact motivates us to use a Markov chain(MC)to capture this type of dependencies and applies the Estimation of Distribution Algorithm(EDA)to improve the quality of the MC.EDA is an evolutionary algorithm directing the search for the optimal solution by learning and sampling probabilistic models through the best individuals of a population at each generation.To show the effectiveness of the proposed approach,we implement it in GROOVE,an open source toolset for designing and model checking graph transformation systems.Experimental results confirm that the proposed approach has a high speed and accuracy in comparison with the existing meta-heuristic and evolutionary techniques in safety analysis of systems specified formally through graph transformations.
文摘Objective To analyze the current research status and development trend of active surveillance of drug safety in China,and to provide reference and suggestions for future research.Methods Using bibliometric methods and with the help of the CiteSpace 6.1.R6,the literature on active surveillance of drug safety in CNKI from 2010 to 2022 was visualized and analyzed in terms of authors,institutions and keywords.Results and Conclusion The research on active surveillance of drug safety in China started late and is in a stable development period.Some Chinese scholars have done more work on active surveillance of drug safety.Additionally,a number of institutions have published some articles and surveillance objects,surveillance methods,and surveillance results are the main research content.However,the cross-institutional cooperation is not close.The traditional Chinese medicine injection,centralized surveillance,and automatic surveillance are the hot spots of research.It is the latest research frontier to use the Chinese hospital pharmacovigilance system to actively monitor drug safety.At present,the research related to active surveillance of drug safety in China is still in the early stage,and more in-depth research is needed to follow up.
基金support provided by the Sichuan Province Science and Technology Achievement Transformation Project (2023ZHCG0063).
文摘In order to analysis the oxygen distribution in the adsorption bed during the hydrogen purification process from oxygen-containing feed gas and the safety of device operation, this article established a non-isothermal model for the pressure swing adsorption (PSA) separation process of 4-component (H_(2)/O_(2)/N_(2)/CH_(4)), and adopted a composite adsorption bed of activated carbon and molecular sieve. In this article, the oxygen distribution in the adsorption bed under different feed gas oxygen contents, different adsorption pressures, and different product hydrogen purity was studied for both vacuuming process and purging process. The study shows that during the process from the end of adsorption to the end of providing purging, the peak value of oxygen concentration in the adsorption bed gradually increases, with the highest value exceeding 30 times the oxygen content of the feed gas. Moreover, the concentration multiplier of oxygen in the adsorption bed increases with the increase of the adsorption pressure, decreases with the increase of the oxygen content in the feed gas, and increases with the decrease of the hydrogen product purity. When the oxygen content in the feed gas reaches 0.3% (vol), the peak value of oxygen concentration in the adsorption bed exceeds 10% (vol), which will make the front part of the oxygen concentration peak fall in an explosion limit range. As the decrease of product hydrogen content, the oxygen concentration peak in the adsorption bed will gradually move forward to the adsorption bed outlet, and even penetrate through the adsorption bed. And during the process of the oxygen concentration peak moving forward, the oxygen will enter the pipeline at the outlet of the adsorption bed, which will make the pipeline space of high-speed gas flow into an explosion range, bringing great risk to the device. The preferred option for safe operation of PSA for hydrogen purification from oxygen-containing feed gas is to deoxygenate the feed gas. When deoxygenation is not available, a lower adsorption pressure and a higher product hydrogen purity (greater than or equal to 99.9% (vol)) can be used to avoid the gas in the adsorption bed outlet pipeline being in the explosion range.
基金Model Study on the Care Effectiveness of Intergenerational Care for Disabled Elderly in Rural Areas under the Background of Silver Age(School level Project Y24-08)。
文摘Objective: To examine the daily life care, spiritual comfort, and fall safety care needs of the elderly in urban and rural areas of Tangshan, along with their influencing factors. Methods: From August 2022 to April 2023, an investigation was conducted among urban and rural elderly individuals aged over 75 years in Tangshan City using the Activities of Daily Living Scale, the Revised Community Elderly Fall Risk Assessment Tool, and the Loneliness Scale. Results: The study included 750 urban and 740 rural elderly individuals aged over 75 years. Matrix analysis revealed a significant proportion of fall safety care needs across various daily life and spiritual care requirements. Multiple factor analysis indicated that advanced age, lower education levels, a greater number of chronic diseases, and lower levels of family and social support were associated with higher care demands among the elderly in both urban and rural areas. These differences were statistically significant (P < 0.05). Conclusion: The elderly in urban and rural areas demonstrate a high demand for fall safety care. Particular attention should be given to individuals with lower education levels, those who are widowed, those with multiple chronic diseases, and those with low levels of family and social support to better meet the diverse care needs of this population.
文摘An improved safety analysis based on the causality diagram for the complex system of micro aero-engines is presented.The study is examined by using the causality diagram in analytical failure cases due to rupture or pentration in the receiver of micro turbojet engine casing,and the comparisons are also made with the results from the traditional fault tree analysis.Experimental results show two main advantages：（1）Quantitative analysis which is more reliable for the failure analysis in jet engines can be produced by the causality diagram analysis;（2）Graphical representation of causality diagram is easier to apply in real test cases and more effective for the safety assessment.
基金Innovation Plan of Aero Engine Complex System Safety by the Ministry of Education Chang Jiang Scholars of China (IRT0905)
文摘This paper presents an application of global sensitivity analysis for system safety analysis of reciprocating aircraft engine. Compared with local sensitivity analysis results, global sensitivity analysis could provide more information on parameter inter- actions, which are significant in complex system safety analysis. First, a deterministic aviation reciprocating engine thermody- namics model is developed and parameters of interest are defined as random variables. Then, samples are generated by Monte Carlo method for the parameters used in engine model on the basis of definition of factor distribution. Eventually, results from engine model are generated and importance indices are calculated. Based on the analysis results, design is improved to satisfy the airworthiness requirements. The results reveal that by using global sensitivity analysis, the parameters could be ranked with respect to their importance, including first order indices and total sensitivity indices. By reducing the uncertainty of parameters and adjusting the range of inputs, safety criteria would be satisfied.
文摘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.
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.
基金Supported by Major Project of Chinese National Programs for Fundamental Research and Development Program(2009CB219401)Key Project of Natural Science Foundation of China(40534019)
文摘According to the ecological safety evaluation index data of land-use change in Ji'an City from 1999 to 2008,positive treatment on selected reverse indices is conducted by Reciprocal Method.Meanwhile,Index Method is used to standardize the selected indices,and Principal Component Analysis is applied by using year as a unit.FB is obtained,which is related with the ecological safety of land-use change from 1999 to 2008.According to the scientific,integrative,hierarchical,practical and dynamic principles,ecological safety evaluation index system of land-use change in Ji'an City is established.Principal Component Analysis and evaluation model are used to calculate four parameters,including the natural resources safety index of land use,the socio-economic safety indicators of land use,the eco-environmental safety index of land use,and the ecological safety degree of land use in Ji'an City.Result indicates that the ecological safety degree of land use in Ji'an City shows a slow upward trend as a whole.At the same time,ecological safety degree of land-use change is relatively low in Ji'an City with the safety value of 0.645,which is at a weak safety zone and needs further monitoring and maintenance.
文摘As longwall caving mining method prevails rapidly in China coal mines, amount of gas emission from longwall faces and goaf area increased significantly. Using traditional gas drainage methods, such as drilling upward holes to roof strata in tailgate or drilling inseam and cross-measure boreholes, could not meet methane drainage requirements in a gassy mine. The alternative is to drill boreholes from surface down to the Iongwall goaf area to drain the gas out. As soon as a coal seam is extracted out, the upper rock strata above the goaf start to collapse or become fractured depending upon the rock characteristics and the height above the coal seam. During overlying rock strata being fractured, boreholes in the area may be damaged due to ground movement after the passage of the Iongwall face. The sudden damage of a borehole may cause a Iongwall production halt or even a serious mine accident. A theoretical calculation of the stability of surface boreholes in mining affected area is introduced along with an example of determination of borehole and casing diameters is given for demonstration. By using this method for the drilling design, the damage of surface boreholes caused by excessive mining induced displacement can be effectively reduced if not totally avoided. Borehole and casing diameters as well as characteristics of filling materials can be determined using the proposed method by calculating the horizontal movement and vertical stain at different borehole depths.
基金Project 70771105 supported by the National Natural Science Foundation of China
文摘In recent years improper allocation of safety input has prevailed in coal mines in China, which resulted in the frequent accidents in coal mining operation. A comprehensive assessment of the input efficiency of coal mine safety should lead to improved efficiency in the use of funds and management resources. This helps government and enterprise managers better understand how safety inputs are used and to optimize allocation of resources. Study on coal mine＇s efficiency assessment of safety input was con- ducted in this paper. A C^2R model with non-Archimedean infinitesimal vector based on output is established after consideration of the input characteristics and the model properties. An assessment of an operating mine was done using a specific set of input and output criteria. It is found that the safety input was efficient in 2002 and 2005 and was weakly efficient in 2003. However, the efficiency was relatively low in both 2001 and 2004. The safety input resources can be optimized and adjusted by means of projection theory. Such analysis shows that, on average in 2001 and 2004, 45% of the expended funds could have been saved. Likewise, 10% of the safety management and technical staff could have been eliminated and working hours devoted to safety could have been reduced by 12%. These conditions could have Riven the same results.
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 rood safety analysis and risk assessment with state of the art technologies is of utmost importance thereof. With applications as exemplified by microfiuidic 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.
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Safety monitoring and stability analysis of high slopes are important for high dam construction in high mountainous regions or precipitous gorges. In this paper, deformation characteristics of toppling block at upper abutment, deforming tensile rip wedge in the middle part and deep fractures are comprehensively analyzed based on the geological conditions, construction methods and monitoring results of left abutment slope in Jinping Ⅰ hydropower station. Safety analyses of surface and shallow-buried rock masses and the corresponding anchorage system are presented. The monitoring results indicate that the global stability of the large wedge block in the left abutment is effectively under control, and the abutment slope is stable in a global sense. After the completion of excavation, the deformations of toppling block at the top of the slope and deep fracture zone continue at a very low rate, which can be explained as 'rock mass creep'. Further monitoring and analysis are needed.
基金the National Natural Science Foundation of China(No.51175284)the Science and Technology Program of Education Committee of Beijing Municipality(No.SQKM201211232002)
文摘A systematic safety analysis method is presented to guide the whole analysis process starting with safety analysis requirement and ending with technical and economical evaluation of the knowledge model and the arrangement of sensors. The method consists of five phases, including data acquisition on factual evidence and collecting design, manufacturing, and installation data of equipment; establishing knowledge model; measurable analysis and selection of sensors as well cost evaluation; knowledge description; and overall evaluation. The proposed method is used for safety analysis of hydraulic power generating units and the analysis results validate the method very well.
基金National Natural Science Foundation of China under Grant Nos.51138001 and 51479027
文摘Abstract： 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Innovation Plan of Aero Engine Complex System Safety by the Ministry of Education Chang Jiang Scholars of China (IRT0905)
文摘In order to ensure the safety of engine life limited parts （ELLP） according to airworthiness regulations, a numerical approach integrating one-way fluid structure interaction （FSI） and probabilistic risk assessment （PRA） is developed, by which the variation of flow parameters in a rotor-stator cavity on the safety of gas turbine disks is investigated. The results indicate that the flow parameters affect the probability of fracture of a gas turbine disk since they can change the distribution of stress and temperature of the disk. The failure probability of the disk rises with increasing rotation Reynolds number and Chebyshev number, but descends with increasing inlet Reynolds number. In addition, a sampling based sensitivity analysis with finite difference method is conducted to determine the sensitivities of the safety with respect to the flow parameters. The sensitivity estimates show that the rotation Reynolds number is the dominant variable in safety analysis of a rotor-stator cavity among the flow parameters.
基金supported by National Program on Key Basic Research Project(2014CB744903)National Natural Science Foundation of China(61673270)+5 种基金Natural Science Foundation of Shanghai(20ZR1427800)New Young Teachers Launch Program of Shanghai Jiaotong University(20X100040036)Shanghai Pujiang Program(16PJD028)Shanghai Industrial Strengthening Project(GYQJ-2017-5-08)Shanghai Science and Technology Committee Research Project(17DZ1204304)Shanghai Engineering Research Center of Civil Aircraft Flight Testing。
文摘With the continuous advancement of the avionics system,crew members are correspondingly reduced,and Single Pilot Operations(SPO)has attracted widespread attention from scholars.To meet the flight requirements in SPO mode,it is necessary to further strengthen air-ground coordination system integration,but at the same time,there will be some safety issues caused by resource integration,function fusion,and task synthesis.Aimed at the safety problems caused by task synthesis,an efficient differential bicluster mining algorithm--DFCluster algorithm is proposed in this paper to discover potential hazardous elements or propagation mechanisms through mining the resource-function matrixes.To mine efficiently,several pruning techniques are designed for generating maximal biclusters without candidate maintenance.The experimental results show that the DFCluster algorithm is more efficient than the existing differential biclustering algorithms under different scales of artificial datasets and public datasets.Then,a typical flight scenario is designed based on SPO air-ground collaborative system architecture,and combined with our proposed DFCluster algorithm for task synthesis safety analysis.Based on the mining results,the SPO airground collaborative system architecture is modified,which ultimately improves the safety of the SPO system.
