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 b...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.展开更多
Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of...Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.展开更多
Based on fuzzy integrated evaluation theory, the safety of coal industry was analyzed, the factors affecting the safety of coal industry was considered, and its fuzzy in- tegrated estimating theory and results were gi...Based on fuzzy integrated evaluation theory, the safety of coal industry was analyzed, the factors affecting the safety of coal industry was considered, and its fuzzy in- tegrated estimating theory and results were given. Finally this paper proposed a new method of industry safety estimation. According to this method, we can integrate the fac- tors affecting coal industry and deal with the parameters and targets of evaluating factors by quantitative analysis, thus give a scientific and reasonable safety degree analyzing evaluation.展开更多
With the increasing public consciousness on environmental issues, chemical products and process designs require simultaneous satisfaction and compromise of environmental and economical requirements. To fulfill the two...With the increasing public consciousness on environmental issues, chemical products and process designs require simultaneous satisfaction and compromise of environmental and economical requirements. To fulfill the two conflicting while complementary objectives, a systematic approach for life cycle design of a chemical product is proposed in this article. Multiattribute decision-making is adopted in a trade-off consideration of both technical economical evaluation and environmental impacts assessment using the analytic hierarchy process (AHP) approach. On the basis of an evaluation of the relative importance of the criteria multicriteria decision making is performed. In this study, an AHP model is used to derive single a criteria score by analyzing the environmental impact and life cycle cost of a product, respectively. And a fluctuant weight analysis is put forth to calculate the integrated index of the product to enable products to be ranked or selected intuitionally and conveniently. The proposed AHP model has been applied to a case study, a comparative study on chamber cleaning with NF3 and C2F6. The resuits show that the protposed AHP model is Capable of providing a rational and relevant evaluation.展开更多
The safety status of the coal mines is closely correlated with the operating status and its changes of the whole working system in the coal mines, and the safety system is the sub system of the whole production system...The safety status of the coal mines is closely correlated with the operating status and its changes of the whole working system in the coal mines, and the safety system is the sub system of the whole production system. In this paper, based on the analysis of the complicacy of the safety sub system and its affecting factors, the theory basis of the indexes system of the safety assessment was studied, including the establishing principles of the indexes system , the structure of the indexes system, the determining methods of the assessment indexes. The complete indexes system was established for the safety assessment of the coal mines in the paper.展开更多
Some super high arch dams ( SHADs), like Xiluodu Arch Dam, after their heights reaching the magnitude of 300 m, confront lots of technical challenges in design and construction. Several crucial technologies of 6 SHA...Some super high arch dams ( SHADs), like Xiluodu Arch Dam, after their heights reaching the magnitude of 300 m, confront lots of technical challenges in design and construction. Several crucial technologies of 6 SHADs will be reviewed and discussed in this and consecutive papers, including Xiluodu, Jinping I in China, Baktiary in Iran, ete. , on the topics of the research method, criterion for evaluation and engineering application of dam safety analysis and evaluation, reasonable dam base interface, dam shape optimization, comprehensive treatments of complex foundation, anti-seismic engineering, dam construction material, concrete placement and temperature control, instrumentation and monitoring of dam operation, etc. This paper will mainly focus on the overall safety of SHADs, reasonable dam base interface analysis and evaluation and their engineering application.展开更多
Hydrodynamic analysis is one of the key steps in safety assessment ot a structure m waves, lvlany optloll~ axe available for answering challenge raised from marine and offshore energy industry, from costly three dimen...Hydrodynamic analysis is one of the key steps in safety assessment ot a structure m waves, lvlany optloll~ axe available for answering challenge raised from marine and offshore energy industry, from costly three dimensional CFD to the efficient but not perfect boundary element models. Focus on the boundary element methods, analysis methods for the interaction of waves and structures are discussed. Those boundary element models cover frequency domain and time domain, linear and non-linear. Special attention is pay to the problems encountered in those models and approaches we adopted for their engineering solution.展开更多
Natural gas is one of the key energy resources for Turkey due to fact that 32% of annual primary energy supply and 45% of annual electricity production is obtained from natural gas with also common usage of residentia...Natural gas is one of the key energy resources for Turkey due to fact that 32% of annual primary energy supply and 45% of annual electricity production is obtained from natural gas with also common usage of residential and industrial zones. In this study, the supply security of natural gas was taken into consideration with strategic criteria of energy policy with the SWOT (strengths, weaknesses, opportunities and threats) analysis and the future projection for Turkey. It has been concluded on geopolitics criteria, domestic production and research for resources must be stimulated as high as possible and participation to abroad resources must be implemented.展开更多
The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave headi...The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method(FEM) . Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis,Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory,fatigue damage is characterized by an S-N relationship,and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.展开更多
As being at the head of the establishment, the hospital manager's major concern is food safety in his hospital. Unfortunately, because of their health weaknesses, patients are more susceptible to foodborne illness th...As being at the head of the establishment, the hospital manager's major concern is food safety in his hospital. Unfortunately, because of their health weaknesses, patients are more susceptible to foodborne illness than any other population group As match as food prepared according to less stringent hygiene's rules can infect or intoxicate more than it would be in a healthy population, as hygiene's rules must be observed in a particularly strict way, at the kitchen where meals are prepared for health care facilities. In fact, hospitals' food hygiene's rules are those who defined catering. They are made to avoid food contamination and microbial growth throughout the food chain from raw materials' delivery to the consumer. The main objective of taking the meal as a patients' tracer is to detect and study the infection's risk associated with feeding at hospital, and to provide practical tools to better manage this risk. Methodology was based on an analysis of the last six years' work concerning hygiene's audits and bacteriological analyses. The results showed that the food infectious risk has an important frequency, on one side; on another, they were used as a standard model of such risk's management.展开更多
Soil dynamic parameters,including dynamic shear modulus ratio and damping ratio,have important effects on the results of layered soil earthquake response. In this paper,the mean parameter values of silty clay in diffe...Soil dynamic parameters,including dynamic shear modulus ratio and damping ratio,have important effects on the results of layered soil earthquake response. In this paper,the mean parameter values of silty clay in different depths are obtained after statistical analysis of the experimental soil dynamic data from 20 recent site seismic safety evaluation reports in the Beijing area. Furthermore,based on two typical engineering sites,the influence of four different soil dynamic parameters,the statistic mean values,experimental values, values recommended by Yuan Xiaoming,and the values recommended in the code for seismic safety evaluation of engineering sites( DB001-94) are analyzed. The result shows that mean statistical values are applicable to seismic safety evaluation work in the Beijing area,especially for some inter-layered silty clays whose undisturbed soil samples are hard to obtain.展开更多
This paper gives a brief introduction to the emergency handling of Tangjiashan barrier lake.Some technologies for the application of geological and topographical data are summarized and the mechanism of formation of a...This paper gives a brief introduction to the emergency handling of Tangjiashan barrier lake.Some technologies for the application of geological and topographical data are summarized and the mechanism of formation of a barrier lake is analyzed.Based on the safety status evaluation,the dam breach flood point is calculated.The paper concludes with discussion of the practical effects of emergency handling scenarios and different drainage channel designs.展开更多
The Lower Yangtze River-South Yellow Sea Seismic Zone,located at the southeast of the Northern China Seismic Zone, characterized by moderate-strong earthquakes, is an intensive earthquake zone,which is controlled by a...The Lower Yangtze River-South Yellow Sea Seismic Zone,located at the southeast of the Northern China Seismic Zone, characterized by moderate-strong earthquakes, is an intensive earthquake zone,which is controlled by a series of faults within the Lower Yangtze River-South Yellow Sea Seismic Zone. This article counts and calculates the bvalue,V 4 and energy density value of medium-small earthquakes by taking full advantage of the latest data from regional seismic stations,reviews data of historical earthquakes and seismic structure,and discusses the relationship between spatial distribution of the b-value, historical strong earthquakes and spatial distribution of energy density of medium-small earthquakes,and further investigates the seismic activity of the Lower Yangtze River- South Yellow Sea Seismic Zone. This article obtains seismic activity parameters of the Lower Yangtze River-South Yellow Sea Seismic Zone as calculation parameters for probabilistic seismic hazard analysis,and discusses the trend of this seismic zone in the next one hundred years and deduces the potential seismic hazard region within this seismic zone,which provides references and methods for long-term prediction on seismic activity. The research results are significant to seismic zoning, seismic safety evaluation of engineering sites and long-term prediction of seismic activity.展开更多
As a novel heart rate lowing agent, ivabradine can reduce the heart rate by inhibiting the If (pacemaker) current in the sinoatrial node without affecting blood pressure or left ventricular systolic function. Howeve...As a novel heart rate lowing agent, ivabradine can reduce the heart rate by inhibiting the If (pacemaker) current in the sinoatrial node without affecting blood pressure or left ventricular systolic function. However, the safety of ivabradine remains controversial. In the present work, we aimed to assess any risk of cardiovascular mortality, bradycardia, phosphenes and atrial fibrillation associated with the ivabradine administration by recta-analysis. Studies were retrieved from PubMed, EMBASE, MEDLINE, Web of Science, Cochrane, www.clinicaltrials.gov web site and related conferences. Randomized controlled trials comparing ivabradine with comparators were identified and analyzed. Two reviewers independently extracted relevant information from the eligible trials and processed the data. This recta-analysis was performed by using Review Manager (5.3) and Stata (14.1) software. Moreover, sensitivity analysis and publication bias of the included studies were evaluated. A total of 12 randomized controlled trials meeting the inclusion criteria were included. Results of the meta-analysis revealed that there was no significant difference between ivabradine group and control groups in cardiovascular mortality (RR = 0.97, 95% CI: 0.89-1.06, P = 0.49). While the administration of ivabradine was associated with a significant increase in the incidence of bradycardia (RR = 3.90, 95% CI: 2.47-6.17, P〈0.00001) and phosphenes (RR = 4.95, 95% CI: 3.24-7.55, P〈0.00001) as well as atrial fibrillation (RR = 1.24, 95% CI: 1.07-1.43, P = 0.003). High quality of the included studies was confirmed by quality assessment. No publication bias was observed, and sensitivity analysis confirmed that the obtained results were stable. In conclusion, the meta-analysis proved that the use of ivabradine was associated with a significant increase in the risk of bradycardia, phosphenes and atrial fibrillation. Therefore, clinicians need to take these risks into account when using ivabradine in treatment.展开更多
With the promotion of agricultural ecological civilization construction in China, agricultural ecological security has received increasing attention. How to ensure agricultural ecological security has become a great c...With the promotion of agricultural ecological civilization construction in China, agricultural ecological security has received increasing attention. How to ensure agricultural ecological security has become a great concern for many scholars. As an important agricultural province in China, Hubei is of great significance to Chinese food security and agricultural sustainable development. This paper aims to establish an index system of agricultural ecological security and security classification of Hubei via Analytic Hierarchy Process and Pressure-State-Response methods. An evaluation of agricultural ecological security in Hubei, with a base of the national average value in 2015, reveals that the security degree has increased by 0.07566 from 0.90150 in 2005 to 0.97716 in 2015. Results show that agricultural ecological security in Hubei has improved but failed to reach the national average and there is still large space for improvement of the security level, considering a trend of deterioration in some indexes, such as per capita water resources, population density, per unit area pesticide load of farmland, forest coverage, grassland degradation rate and average annual precipitation. Influencing factors, especially population spatial distribution, misconduct in agricultural production, insufficient ability in agricultural natural disaster prevention, deficiency of agro-ecological technology of agricultural ecological security in Hubei are analyzed. For improvement of the degree of agricultural ecological security in Hubei, some countermeasures and suggestions are discussed.展开更多
As a material carrier contributing to human survival and social sustainable development,the ecological environment is declining in its integrity and overall health.With the rapid development of society and economy,it ...As a material carrier contributing to human survival and social sustainable development,the ecological environment is declining in its integrity and overall health.With the rapid development of society and economy,it is currently very necessary to carry out ecological security evaluation research to provide scientific guidance and suggestions for the construction of ecological civilization and the harmonious co-existence between man and nature.Taking Altay region as the research area,this paper collected and integrated regional geological,geographical,cultural,socio-economic,and statistical data,as well as previous research results.Combined with DPSIR and EES framework model,the evaluation index system of land resource ecological security in Altay region was constructed by using the analytic hierarchy process,entropy method and linear weighted summation function method.Using this index system,the evaluation research work was carried out to determine the current state of the security situation and the major threats which should be addressed.(1)The overall ecological security situation of Altay region was relatively safe,while the local ecological security situation was relatively fragile.Among them,the areas with safe and safer ecological environment accounted for 38.72%,while the areas with critically safe status accounted for 30.83%,and the areas with a less safe and unsafe environment accounted for 30.45%.In terms of spatial characteristics,the areas with unsafe ecological environment were mainly distributed in the west and east of the study area,while the areas with good ecological environment were distributed in the north of the study area.(2)Large-scale mining activities,frequent geological disasters,large-scale reclamation and long-term cultivation of arable land,and long-term large-scale grazing activities resulting in the destruction of grassland and vegetation were the main factors leading to the prominent ecological security problems of land resources in the Altay region.Therefore,in the process of the continuous development of the urban economy,we should pay more attention to the harmony between man and nature,and also actively and effectively advocate and implement certain policies and measures,such as returning farmland to forest,returning grazing land to grassland and integrating the mining of mineral resources.展开更多
Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ens...Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ensuring the structural stability and avoiding the wrinkling of membrane structures.In this paper,the analysis procedures are presented and the wrinkling of membrane structure,representing a major behavioral performance of the structure,is included with the modified constitutive relationship method.As for the judgment of the membrane wrinkling,the principal stress-strain criteria are incorporated.Thereafter,an integrated algorithm is developed,in which the Newton-Raphson method and updated Lagrange formulation are adopted.With the proposed algorithm,two fabric roof structures are analyzed.Results show that the presented method is feasible and reliable.展开更多
基金Project(2023YFB4302500)supported by the National Key R&D Program of ChinaProject(52078485)supported by the National Natural Science Foundation of ChinaProjects(2021-Major-16,2021-Special-08)supported by the Science and Technology Research and Development Program Project of China Railway Group Limited。
文摘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.
基金Projects(51278382,51479050)supported by the National Natural Science Foundation of ChinaProject(2015CB057901)supported by the National Key Basic Research Program of China+3 种基金Project(201501035-03)supported by the Public Service Sector R&D Project of Ministry of Water Resource of ChinaProject(2014B06814)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(B13024)supported by the"111"ProjectProject(YK913004)supported by the Open Foundation of Key Laboratory of Failure Mechanism and Safety Control Techniques of Earthrock Dam of the Ministry of Water Resources,China
文摘Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.
文摘Based on fuzzy integrated evaluation theory, the safety of coal industry was analyzed, the factors affecting the safety of coal industry was considered, and its fuzzy in- tegrated estimating theory and results were given. Finally this paper proposed a new method of industry safety estimation. According to this method, we can integrate the fac- tors affecting coal industry and deal with the parameters and targets of evaluating factors by quantitative analysis, thus give a scientific and reasonable safety degree analyzing evaluation.
基金Supported by the National Natural Science Foundation of China (No.20376025, No.20536020) the China Excellent YoungScientist Fund (No.20225620).
文摘With the increasing public consciousness on environmental issues, chemical products and process designs require simultaneous satisfaction and compromise of environmental and economical requirements. To fulfill the two conflicting while complementary objectives, a systematic approach for life cycle design of a chemical product is proposed in this article. Multiattribute decision-making is adopted in a trade-off consideration of both technical economical evaluation and environmental impacts assessment using the analytic hierarchy process (AHP) approach. On the basis of an evaluation of the relative importance of the criteria multicriteria decision making is performed. In this study, an AHP model is used to derive single a criteria score by analyzing the environmental impact and life cycle cost of a product, respectively. And a fluctuant weight analysis is put forth to calculate the integrated index of the product to enable products to be ranked or selected intuitionally and conveniently. The proposed AHP model has been applied to a case study, a comparative study on chamber cleaning with NF3 and C2F6. The resuits show that the protposed AHP model is Capable of providing a rational and relevant evaluation.
文摘The safety status of the coal mines is closely correlated with the operating status and its changes of the whole working system in the coal mines, and the safety system is the sub system of the whole production system. In this paper, based on the analysis of the complicacy of the safety sub system and its affecting factors, the theory basis of the indexes system of the safety assessment was studied, including the establishing principles of the indexes system , the structure of the indexes system, the determining methods of the assessment indexes. The complete indexes system was established for the safety assessment of the coal mines in the paper.
文摘Some super high arch dams ( SHADs), like Xiluodu Arch Dam, after their heights reaching the magnitude of 300 m, confront lots of technical challenges in design and construction. Several crucial technologies of 6 SHADs will be reviewed and discussed in this and consecutive papers, including Xiluodu, Jinping I in China, Baktiary in Iran, ete. , on the topics of the research method, criterion for evaluation and engineering application of dam safety analysis and evaluation, reasonable dam base interface, dam shape optimization, comprehensive treatments of complex foundation, anti-seismic engineering, dam construction material, concrete placement and temperature control, instrumentation and monitoring of dam operation, etc. This paper will mainly focus on the overall safety of SHADs, reasonable dam base interface analysis and evaluation and their engineering application.
文摘Hydrodynamic analysis is one of the key steps in safety assessment ot a structure m waves, lvlany optloll~ axe available for answering challenge raised from marine and offshore energy industry, from costly three dimensional CFD to the efficient but not perfect boundary element models. Focus on the boundary element methods, analysis methods for the interaction of waves and structures are discussed. Those boundary element models cover frequency domain and time domain, linear and non-linear. Special attention is pay to the problems encountered in those models and approaches we adopted for their engineering solution.
文摘Natural gas is one of the key energy resources for Turkey due to fact that 32% of annual primary energy supply and 45% of annual electricity production is obtained from natural gas with also common usage of residential and industrial zones. In this study, the supply security of natural gas was taken into consideration with strategic criteria of energy policy with the SWOT (strengths, weaknesses, opportunities and threats) analysis and the future projection for Turkey. It has been concluded on geopolitics criteria, domestic production and research for resources must be stimulated as high as possible and participation to abroad resources must be implemented.
文摘The procedure of reliability-based fatigue analysis of liquefied natural gas(LNG) carrier of membrane type under wave loads is presented. The stress responses of the hotspots in regular waves with different wave heading angles and wave lengths are evaluated by global ship finite element method(FEM) . Based on the probabilistic distribution function of hotspots' short-term stress-range using spectral-based analysis,Weibull distribution is adopted and discussed for fitting the long-term probabilistic distribution of stress-range. Based on linear cumulative damage theory,fatigue damage is characterized by an S-N relationship,and limit state function is established. Structural fatigue damage behavior of several typical hotspots of LNG middle ship section is clarified and reliability analysis is performed. It is believed that the presented results and conclusions can be of use in calibration for practical design and initial fatigue safety evaluation for membrane type LNG carrier.
文摘As being at the head of the establishment, the hospital manager's major concern is food safety in his hospital. Unfortunately, because of their health weaknesses, patients are more susceptible to foodborne illness than any other population group As match as food prepared according to less stringent hygiene's rules can infect or intoxicate more than it would be in a healthy population, as hygiene's rules must be observed in a particularly strict way, at the kitchen where meals are prepared for health care facilities. In fact, hospitals' food hygiene's rules are those who defined catering. They are made to avoid food contamination and microbial growth throughout the food chain from raw materials' delivery to the consumer. The main objective of taking the meal as a patients' tracer is to detect and study the infection's risk associated with feeding at hospital, and to provide practical tools to better manage this risk. Methodology was based on an analysis of the last six years' work concerning hygiene's audits and bacteriological analyses. The results showed that the food infectious risk has an important frequency, on one side; on another, they were used as a standard model of such risk's management.
基金sponsored jointly by the Research Grants from Institute of Crustal Dynamics,CEA(NO. ZDJ2007-7)the 2007 Special Research Project 8-50 of the Department of Finance
文摘Soil dynamic parameters,including dynamic shear modulus ratio and damping ratio,have important effects on the results of layered soil earthquake response. In this paper,the mean parameter values of silty clay in different depths are obtained after statistical analysis of the experimental soil dynamic data from 20 recent site seismic safety evaluation reports in the Beijing area. Furthermore,based on two typical engineering sites,the influence of four different soil dynamic parameters,the statistic mean values,experimental values, values recommended by Yuan Xiaoming,and the values recommended in the code for seismic safety evaluation of engineering sites( DB001-94) are analyzed. The result shows that mean statistical values are applicable to seismic safety evaluation work in the Beijing area,especially for some inter-layered silty clays whose undisturbed soil samples are hard to obtain.
文摘This paper gives a brief introduction to the emergency handling of Tangjiashan barrier lake.Some technologies for the application of geological and topographical data are summarized and the mechanism of formation of a barrier lake is analyzed.Based on the safety status evaluation,the dam breach flood point is calculated.The paper concludes with discussion of the practical effects of emergency handling scenarios and different drainage channel designs.
基金sponsored by Institute of Crustal Dynamics,China Earthquake Administration ( ZDJ2013-05 )the sub-project from the Ministry of National Science and Technique's project( 2011ZX05056-001-02)the Special Scientific Research Fund of Seismological Public Welfare Profession of China ( 200708055)
文摘The Lower Yangtze River-South Yellow Sea Seismic Zone,located at the southeast of the Northern China Seismic Zone, characterized by moderate-strong earthquakes, is an intensive earthquake zone,which is controlled by a series of faults within the Lower Yangtze River-South Yellow Sea Seismic Zone. This article counts and calculates the bvalue,V 4 and energy density value of medium-small earthquakes by taking full advantage of the latest data from regional seismic stations,reviews data of historical earthquakes and seismic structure,and discusses the relationship between spatial distribution of the b-value, historical strong earthquakes and spatial distribution of energy density of medium-small earthquakes,and further investigates the seismic activity of the Lower Yangtze River- South Yellow Sea Seismic Zone. This article obtains seismic activity parameters of the Lower Yangtze River-South Yellow Sea Seismic Zone as calculation parameters for probabilistic seismic hazard analysis,and discusses the trend of this seismic zone in the next one hundred years and deduces the potential seismic hazard region within this seismic zone,which provides references and methods for long-term prediction on seismic activity. The research results are significant to seismic zoning, seismic safety evaluation of engineering sites and long-term prediction of seismic activity.
文摘As a novel heart rate lowing agent, ivabradine can reduce the heart rate by inhibiting the If (pacemaker) current in the sinoatrial node without affecting blood pressure or left ventricular systolic function. However, the safety of ivabradine remains controversial. In the present work, we aimed to assess any risk of cardiovascular mortality, bradycardia, phosphenes and atrial fibrillation associated with the ivabradine administration by recta-analysis. Studies were retrieved from PubMed, EMBASE, MEDLINE, Web of Science, Cochrane, www.clinicaltrials.gov web site and related conferences. Randomized controlled trials comparing ivabradine with comparators were identified and analyzed. Two reviewers independently extracted relevant information from the eligible trials and processed the data. This recta-analysis was performed by using Review Manager (5.3) and Stata (14.1) software. Moreover, sensitivity analysis and publication bias of the included studies were evaluated. A total of 12 randomized controlled trials meeting the inclusion criteria were included. Results of the meta-analysis revealed that there was no significant difference between ivabradine group and control groups in cardiovascular mortality (RR = 0.97, 95% CI: 0.89-1.06, P = 0.49). While the administration of ivabradine was associated with a significant increase in the incidence of bradycardia (RR = 3.90, 95% CI: 2.47-6.17, P〈0.00001) and phosphenes (RR = 4.95, 95% CI: 3.24-7.55, P〈0.00001) as well as atrial fibrillation (RR = 1.24, 95% CI: 1.07-1.43, P = 0.003). High quality of the included studies was confirmed by quality assessment. No publication bias was observed, and sensitivity analysis confirmed that the obtained results were stable. In conclusion, the meta-analysis proved that the use of ivabradine was associated with a significant increase in the risk of bradycardia, phosphenes and atrial fibrillation. Therefore, clinicians need to take these risks into account when using ivabradine in treatment.
基金Key Project of National Social Science Fund of China(15AZD062)Graduate Education Innovation Program Fund of Zhongnan University of Economics and Law(2016Y1054)
文摘With the promotion of agricultural ecological civilization construction in China, agricultural ecological security has received increasing attention. How to ensure agricultural ecological security has become a great concern for many scholars. As an important agricultural province in China, Hubei is of great significance to Chinese food security and agricultural sustainable development. This paper aims to establish an index system of agricultural ecological security and security classification of Hubei via Analytic Hierarchy Process and Pressure-State-Response methods. An evaluation of agricultural ecological security in Hubei, with a base of the national average value in 2015, reveals that the security degree has increased by 0.07566 from 0.90150 in 2005 to 0.97716 in 2015. Results show that agricultural ecological security in Hubei has improved but failed to reach the national average and there is still large space for improvement of the security level, considering a trend of deterioration in some indexes, such as per capita water resources, population density, per unit area pesticide load of farmland, forest coverage, grassland degradation rate and average annual precipitation. Influencing factors, especially population spatial distribution, misconduct in agricultural production, insufficient ability in agricultural natural disaster prevention, deficiency of agro-ecological technology of agricultural ecological security in Hubei are analyzed. For improvement of the degree of agricultural ecological security in Hubei, some countermeasures and suggestions are discussed.
基金The Key Program of Basic Research of Yunnan Province,China(2019FA017)The Multi-Government International Science and Technology Innovation Cooperation Key Project of National Key Research and Development Program of China(2018YFE0184300)The Postgraduate Scientific Research Fund Project of Yunnan Provincial Department of Education(2021Y501)。
文摘As a material carrier contributing to human survival and social sustainable development,the ecological environment is declining in its integrity and overall health.With the rapid development of society and economy,it is currently very necessary to carry out ecological security evaluation research to provide scientific guidance and suggestions for the construction of ecological civilization and the harmonious co-existence between man and nature.Taking Altay region as the research area,this paper collected and integrated regional geological,geographical,cultural,socio-economic,and statistical data,as well as previous research results.Combined with DPSIR and EES framework model,the evaluation index system of land resource ecological security in Altay region was constructed by using the analytic hierarchy process,entropy method and linear weighted summation function method.Using this index system,the evaluation research work was carried out to determine the current state of the security situation and the major threats which should be addressed.(1)The overall ecological security situation of Altay region was relatively safe,while the local ecological security situation was relatively fragile.Among them,the areas with safe and safer ecological environment accounted for 38.72%,while the areas with critically safe status accounted for 30.83%,and the areas with a less safe and unsafe environment accounted for 30.45%.In terms of spatial characteristics,the areas with unsafe ecological environment were mainly distributed in the west and east of the study area,while the areas with good ecological environment were distributed in the north of the study area.(2)Large-scale mining activities,frequent geological disasters,large-scale reclamation and long-term cultivation of arable land,and long-term large-scale grazing activities resulting in the destruction of grassland and vegetation were the main factors leading to the prominent ecological security problems of land resources in the Altay region.Therefore,in the process of the continuous development of the urban economy,we should pay more attention to the harmony between man and nature,and also actively and effectively advocate and implement certain policies and measures,such as returning farmland to forest,returning grazing land to grassland and integrating the mining of mineral resources.
基金supported by the National Natural Science Foundation of China (Grant Nos. 90815021,50725826)
文摘Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ensuring the structural stability and avoiding the wrinkling of membrane structures.In this paper,the analysis procedures are presented and the wrinkling of membrane structure,representing a major behavioral performance of the structure,is included with the modified constitutive relationship method.As for the judgment of the membrane wrinkling,the principal stress-strain criteria are incorporated.Thereafter,an integrated algorithm is developed,in which the Newton-Raphson method and updated Lagrange formulation are adopted.With the proposed algorithm,two fabric roof structures are analyzed.Results show that the presented method is feasible and reliable.