Risk assessment is a crucial component of collision warning and avoidance systems for intelligent vehicles.Reachability-based formal approaches have been developed to ensure driving safety to accurately detect potenti...Risk assessment is a crucial component of collision warning and avoidance systems for intelligent vehicles.Reachability-based formal approaches have been developed to ensure driving safety to accurately detect potential vehicle collisions.However,they suffer from over-conservatism,potentially resulting in false–positive risk events in complicated real-world applications.In this paper,we combine two reachability analysis techniques,a backward reachable set(BRS)and a stochastic forward reachable set(FRS),and propose an integrated probabilistic collision–detection framework for highway driving.Within this framework,we can first use a BRS to formally check whether a two-vehicle interaction is safe;otherwise,a prediction-based stochastic FRS is employed to estimate the collision probability at each future time step.Thus,the framework can not only identify non-risky events with guaranteed safety but also provide accurate collision risk estimation in safety-critical events.To construct the stochastic FRS,we develop a neural network-based acceleration model for surrounding vehicles and further incorporate a confidence-aware dynamic belief to improve the prediction accuracy.Extensive experiments were conducted to validate the performance of the acceleration prediction model based on naturalistic highway driving data.The efficiency and effectiveness of the framework with infused confidence beliefs were tested in both naturalistic and simulated highway scenarios.The proposed risk assessment framework is promising for real-world applications.展开更多
Predicted no-effect concentration （PNEC） is often used in ecological risk assessment to determine low-risk concentrations for chemicals. In the present study, the chronic data from native saltwater species were used...Predicted no-effect concentration （PNEC） is often used in ecological risk assessment to determine low-risk concentrations for chemicals. In the present study, the chronic data from native saltwater species were used to calculated PNEC values using four methods： log-normal distribution （ETX 2.0）, log-triangle distribution （US EPA＇s water quality criteria procedure）, burr III distribution （BurrliOZ） and traditional assessment fac-tor （AF）. The PNECs that were calculated using four methods ranged from 0.08 μg/L to 1.8 μg/L. Three of the SSD-derived PNECs range from 0.94 to 1.8 μg/L, about a factor of two apart. To demonstrate the use of SSD-based PNEC values and comprehensively estimate the regional ecological risk for cadmium in surface water of the Bohai Sea, in the Liaodong Bay, Bohai Bay, and Laizhou Bay, China, the dissolved cadmium con-centrations were measured and obtained 753 valid data covering 190 stations from July 2006 to November 2007. Based on three ecological risk assessment approaches, namely hazard quotient （HQ）, probabilistic risk quotient and joint probability curve （JPC）, the potential ecological risk of cadmium in surface water of the Liaodong Bay, Bohai Bay, and Laizahou Bay were estimated. Overall, the ecological risk of cadmium to aquatic ecosystem in the whole Bohai Sea was at acceptable ecological risk level, the order of ecological risk was Liaodong Bay〉Bohai Bay〉Laizhou Bay. However, more concerns should be paid to aquatic ecological risk in the Liaodong Bay which is the home of many steel, metallurgy and petrochemical industrial in China.展开更多
As pesticide residues in bayberry has raised serious concern from the public in China, a monitoring survey was carried out during 2013–2014 and 157 samples were analyzed in total. Twenty-three pesticides were detecte...As pesticide residues in bayberry has raised serious concern from the public in China, a monitoring survey was carried out during 2013–2014 and 157 samples were analyzed in total. Twenty-three pesticides were detected among the 44 pesticides analyzed and at least one pesticide was detected in 63% of 99 samples. Whereas 45.6% of samples were found with two or more pesticide residues, and 23.6% of samples with four or more pesticide residues. Probabilistic risk assessments indicated that estimated daily intake（EDI） of cyhalothrin at the P97.5th percentile level is 1.11 times larger than the acceptable daily intake（ADI） for children, the estimated short-term intake（ESTI） at the P97.5th percentile level is 1.9 and 1.78 times larger than the acute reference dose（ARf D） for adult and children, respectively, indicating the potential risk concern from pyrethroids. EDI of the pesticides with anti-androgenic effects ranged from 0.15–2.46 of ADI, the probability of exposure exceeding the ADI was 7.1 and 31.1% for adults and children, respectively, the probability of exposure of pyrethroids exceeding the ADI was 3.8% for children. Exposures for other pesticides and groups were below 1.0. Because the co-occurrence of frequency of cyhalothrin and cypermethrin was 9.55%, the combinations of pesticides detected with anti-androgenic effects has not been found in the present monitoring, the results indicate that the pesticide residues in bayberry will not constitute serious public health risk, however, they are significant for the management of pesticide use on bayberry and dietary health risk in China.展开更多
Fuzzy regression analysis is an important regression analysis method to predict uncertain information in the real world. In this paper, the input data are crisp with randomness;the output data are trapezoid fuzzy numb...Fuzzy regression analysis is an important regression analysis method to predict uncertain information in the real world. In this paper, the input data are crisp with randomness;the output data are trapezoid fuzzy number, and three different risk preferences and chaos optimization algorithm are introduced to establish fuzzy regression model. On the basis of the principle of the minimum total spread between the observed and the estimated values, risk-neutral, risk-averse, and risk-seeking fuzzy regression model are developed to obtain the parameters of fuzzy linear regression model. Chaos optimization algorithm is used to determine the digital characteristic of random variables. The mean absolute percentage error and variance of errors are adopted to compare the modeling results. A stock rating case is used to evaluate the fuzzy regression models. The comparisons with five existing methods show that our proposed method has satisfactory performance.展开更多
Intense pressure from both onshore and offshore oil exploration and exploitation activities, together with the accompanying urbanization and industrialization has resulted in massive contamination of land and water re...Intense pressure from both onshore and offshore oil exploration and exploitation activities, together with the accompanying urbanization and industrialization has resulted in massive contamination of land and water resources in Niger Delta, Nigeria. Whereas crayfish is very sensitive to contaminant in the aquatic environment and constitute an important part of human diet, its quality and safety from environmental pollutant is of serious health concern. Evaluation of dietary intake, potential carcinogenic and non-carcinogenic risk of lead, cadmium, mercury and arsenic exposure via consumption of dried crayfish purchased from major markets in Calabar, Nigeria was carried out between June and August 2021. Thirty-six composite samples of dried crayfish purchased from 180 vendors were used for the study. Heavy metals concentrations were determined using Atomic Absorption Spectrophotometer (Model AA-6800, Japan) after wet digestion. Metals concentrations (Mg/kg) were of the ranges 0.02 - 0.24, 0.14 - 0.86, 0.32 - 0.72, 0.04 - 0.19 for Pb, Cd, Hg and As respectively. The mean content of cadmium and mercury exceeded FAO/ WHO and Commission of European Communities maximum levels for crustaceans. Average Estimated Daily Intake for each of the metals was found to be above the recommended daily intake level except for arsenic. The average estimated daily intake values for Cd and Hg were also above the tolerable upper intake level. Average Target Hazard Quotient of all the metals and Hazard Index of all the markets were below 1.00. The Incremental Lifetime Cancer Risk of the metals was greater than the standard tolerable regulatory risk (10<sup>-4</sup>) for carcinogens. Consumption of crayfish purchased from major markets in Calabar could pose a range of carcinogenic and non-carcinogenic human health risks.展开更多
In an integrated energy system,source-load multiple uncertainties and correlations lead to an over-limit risk in operating state,including voltage,temperature,and pressure over-limit.Therefore,efficient probabilistic ...In an integrated energy system,source-load multiple uncertainties and correlations lead to an over-limit risk in operating state,including voltage,temperature,and pressure over-limit.Therefore,efficient probabilistic energy flow calculation methods and risk assessment theories applicable to integrated energy systems are crucial.This study proposed a probabilistic energy flow calculation method based on polynomial chaos expansion for an electric-heat-gas integrated energy system.The method accurately and efficiently calculated the over-limit probability of the system state variables,considering the coupling conditions of electricity,heat,and gas,as well as uncertainties and correlations in renewable energy unit outputs and multiple types of loads.To further evaluate and quantify the impact of uncertainty factors on the over-limit risk,a global sensitivity analysis method for the integrated energy system based on the analysis of covariance theory is proposed.This method considered the source-load correlation and aimed to identify the key uncertainty factors that influence stable operation.Simulation results demonstrated that the proposed method achieved accuracy to that of the Monte Carlo method while significantly reducing calculation time.It effectively quantified the over-limit risk under the presence of multiple source-load uncertainties.展开更多
In this study, 15 mycotoxins were detected in 233 nut and dried fruit samples from China. The 15 mycotoxins included aflatoxins （AFs： AFB1, AFB2, AFG1 and AFG2）, trichothecene toxins （TCs： T-2, ZEA, ENA, ENA1, EN...In this study, 15 mycotoxins were detected in 233 nut and dried fruit samples from China. The 15 mycotoxins included aflatoxins （AFs： AFB1, AFB2, AFG1 and AFG2）, trichothecene toxins （TCs： T-2, ZEA, ENA, ENA1, ENB, ENB1 and BEA）, Alternaria toxins （ATs： TEN, AOH and AME） and ochratoxin A （OTA）. The mycotoxins were detected in 47.6% of the samples and all 15 of the mycotoxins were found. Two samples were positive for AFB1 and exceeded the maximum tolerable levels allowed in China. The contamination levels of the mycotoxins found in nuts, dried jujubes, raisins, dried figs and dried Iongans were in the ranges of 0.1-462.7, 0.2-247.3, 0.8-10.1,0.2-384.1 and 0.1-89.2 μg kg^-1, respectively. Dried figs （80.0%） had the highest incidence of mycotoxins, followed by dried Iongans （60.0%）, dried jujubes （57.1%）, nuts （43.6%） and raisins （26.7%）. The estimated daily intake （EDI） values of each individual mycotoxin and all of the mycotoxins collectively were calculated by both the deterministic approach （DA） and the probability approach （PA）. For risk characterization, dietary exposure to TCs, ATs and OTA through consumption of nuts and dried fruits according to both approaches, showed no health risk to Chinese adults by exposure to either individual mycotoxins or in combination. To the best of our knowledge, this is the first work in which risk assessment of multimycotoxins is performed, specifically including the emerging ENNs and BEA, in nuts and dried fruits of China.展开更多
International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to me...International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project's NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project's NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making.展开更多
基金supported by the proactive SAFEty systems and tools for a constantly UPgrading road environment(SAFE-UP)projectfunding from the European Union’s Horizon 2020 Research and Innovation Program(861570)。
文摘Risk assessment is a crucial component of collision warning and avoidance systems for intelligent vehicles.Reachability-based formal approaches have been developed to ensure driving safety to accurately detect potential vehicle collisions.However,they suffer from over-conservatism,potentially resulting in false–positive risk events in complicated real-world applications.In this paper,we combine two reachability analysis techniques,a backward reachable set(BRS)and a stochastic forward reachable set(FRS),and propose an integrated probabilistic collision–detection framework for highway driving.Within this framework,we can first use a BRS to formally check whether a two-vehicle interaction is safe;otherwise,a prediction-based stochastic FRS is employed to estimate the collision probability at each future time step.Thus,the framework can not only identify non-risky events with guaranteed safety but also provide accurate collision risk estimation in safety-critical events.To construct the stochastic FRS,we develop a neural network-based acceleration model for surrounding vehicles and further incorporate a confidence-aware dynamic belief to improve the prediction accuracy.Extensive experiments were conducted to validate the performance of the acceleration prediction model based on naturalistic highway driving data.The efficiency and effectiveness of the framework with infused confidence beliefs were tested in both naturalistic and simulated highway scenarios.The proposed risk assessment framework is promising for real-world applications.
基金The National Natural Science Foundation of China under contract No.41106089the National Key Technology Research and Development Program of the Ministry of Science and Technology of China under contract No.2010BAC69B01the Scientific Research Special Fund of Marine Public Welfare Industry under contract No.201005008-1
文摘Predicted no-effect concentration （PNEC） is often used in ecological risk assessment to determine low-risk concentrations for chemicals. In the present study, the chronic data from native saltwater species were used to calculated PNEC values using four methods： log-normal distribution （ETX 2.0）, log-triangle distribution （US EPA＇s water quality criteria procedure）, burr III distribution （BurrliOZ） and traditional assessment fac-tor （AF）. The PNECs that were calculated using four methods ranged from 0.08 μg/L to 1.8 μg/L. Three of the SSD-derived PNECs range from 0.94 to 1.8 μg/L, about a factor of two apart. To demonstrate the use of SSD-based PNEC values and comprehensively estimate the regional ecological risk for cadmium in surface water of the Bohai Sea, in the Liaodong Bay, Bohai Bay, and Laizhou Bay, China, the dissolved cadmium con-centrations were measured and obtained 753 valid data covering 190 stations from July 2006 to November 2007. Based on three ecological risk assessment approaches, namely hazard quotient （HQ）, probabilistic risk quotient and joint probability curve （JPC）, the potential ecological risk of cadmium in surface water of the Liaodong Bay, Bohai Bay, and Laizahou Bay were estimated. Overall, the ecological risk of cadmium to aquatic ecosystem in the whole Bohai Sea was at acceptable ecological risk level, the order of ecological risk was Liaodong Bay〉Bohai Bay〉Laizhou Bay. However, more concerns should be paid to aquatic ecological risk in the Liaodong Bay which is the home of many steel, metallurgy and petrochemical industrial in China.
基金supported by the National Natural Science Foundation of China(31301490)the Zhejiang Provincial Major Scientific and Technology Project for Agriculture,China(2015C02043)the Zhejiang Provincial Major Scientific and Research Project for Agriculture,China(ZJNY2017001)
文摘As pesticide residues in bayberry has raised serious concern from the public in China, a monitoring survey was carried out during 2013–2014 and 157 samples were analyzed in total. Twenty-three pesticides were detected among the 44 pesticides analyzed and at least one pesticide was detected in 63% of 99 samples. Whereas 45.6% of samples were found with two or more pesticide residues, and 23.6% of samples with four or more pesticide residues. Probabilistic risk assessments indicated that estimated daily intake（EDI） of cyhalothrin at the P97.5th percentile level is 1.11 times larger than the acceptable daily intake（ADI） for children, the estimated short-term intake（ESTI） at the P97.5th percentile level is 1.9 and 1.78 times larger than the acute reference dose（ARf D） for adult and children, respectively, indicating the potential risk concern from pyrethroids. EDI of the pesticides with anti-androgenic effects ranged from 0.15–2.46 of ADI, the probability of exposure exceeding the ADI was 7.1 and 31.1% for adults and children, respectively, the probability of exposure of pyrethroids exceeding the ADI was 3.8% for children. Exposures for other pesticides and groups were below 1.0. Because the co-occurrence of frequency of cyhalothrin and cypermethrin was 9.55%, the combinations of pesticides detected with anti-androgenic effects has not been found in the present monitoring, the results indicate that the pesticide residues in bayberry will not constitute serious public health risk, however, they are significant for the management of pesticide use on bayberry and dietary health risk in China.
文摘Fuzzy regression analysis is an important regression analysis method to predict uncertain information in the real world. In this paper, the input data are crisp with randomness;the output data are trapezoid fuzzy number, and three different risk preferences and chaos optimization algorithm are introduced to establish fuzzy regression model. On the basis of the principle of the minimum total spread between the observed and the estimated values, risk-neutral, risk-averse, and risk-seeking fuzzy regression model are developed to obtain the parameters of fuzzy linear regression model. Chaos optimization algorithm is used to determine the digital characteristic of random variables. The mean absolute percentage error and variance of errors are adopted to compare the modeling results. A stock rating case is used to evaluate the fuzzy regression models. The comparisons with five existing methods show that our proposed method has satisfactory performance.
文摘Intense pressure from both onshore and offshore oil exploration and exploitation activities, together with the accompanying urbanization and industrialization has resulted in massive contamination of land and water resources in Niger Delta, Nigeria. Whereas crayfish is very sensitive to contaminant in the aquatic environment and constitute an important part of human diet, its quality and safety from environmental pollutant is of serious health concern. Evaluation of dietary intake, potential carcinogenic and non-carcinogenic risk of lead, cadmium, mercury and arsenic exposure via consumption of dried crayfish purchased from major markets in Calabar, Nigeria was carried out between June and August 2021. Thirty-six composite samples of dried crayfish purchased from 180 vendors were used for the study. Heavy metals concentrations were determined using Atomic Absorption Spectrophotometer (Model AA-6800, Japan) after wet digestion. Metals concentrations (Mg/kg) were of the ranges 0.02 - 0.24, 0.14 - 0.86, 0.32 - 0.72, 0.04 - 0.19 for Pb, Cd, Hg and As respectively. The mean content of cadmium and mercury exceeded FAO/ WHO and Commission of European Communities maximum levels for crustaceans. Average Estimated Daily Intake for each of the metals was found to be above the recommended daily intake level except for arsenic. The average estimated daily intake values for Cd and Hg were also above the tolerable upper intake level. Average Target Hazard Quotient of all the metals and Hazard Index of all the markets were below 1.00. The Incremental Lifetime Cancer Risk of the metals was greater than the standard tolerable regulatory risk (10<sup>-4</sup>) for carcinogens. Consumption of crayfish purchased from major markets in Calabar could pose a range of carcinogenic and non-carcinogenic human health risks.
基金supported in part by the National Natural Science Foundation of China(No.51977005)。
文摘In an integrated energy system,source-load multiple uncertainties and correlations lead to an over-limit risk in operating state,including voltage,temperature,and pressure over-limit.Therefore,efficient probabilistic energy flow calculation methods and risk assessment theories applicable to integrated energy systems are crucial.This study proposed a probabilistic energy flow calculation method based on polynomial chaos expansion for an electric-heat-gas integrated energy system.The method accurately and efficiently calculated the over-limit probability of the system state variables,considering the coupling conditions of electricity,heat,and gas,as well as uncertainties and correlations in renewable energy unit outputs and multiple types of loads.To further evaluate and quantify the impact of uncertainty factors on the over-limit risk,a global sensitivity analysis method for the integrated energy system based on the analysis of covariance theory is proposed.This method considered the source-load correlation and aimed to identify the key uncertainty factors that influence stable operation.Simulation results demonstrated that the proposed method achieved accuracy to that of the Monte Carlo method while significantly reducing calculation time.It effectively quantified the over-limit risk under the presence of multiple source-load uncertainties.
基金supported by the National Program for Quality and Safety Risk Assessment of Agricultural Products of China (GJFP2016003 and GJFP2017003)the Scientific and Technological Innovation Project of the Chinese Academy of Agricultural Sciences (CAAS-ASTIP)
文摘In this study, 15 mycotoxins were detected in 233 nut and dried fruit samples from China. The 15 mycotoxins included aflatoxins （AFs： AFB1, AFB2, AFG1 and AFG2）, trichothecene toxins （TCs： T-2, ZEA, ENA, ENA1, ENB, ENB1 and BEA）, Alternaria toxins （ATs： TEN, AOH and AME） and ochratoxin A （OTA）. The mycotoxins were detected in 47.6% of the samples and all 15 of the mycotoxins were found. Two samples were positive for AFB1 and exceeded the maximum tolerable levels allowed in China. The contamination levels of the mycotoxins found in nuts, dried jujubes, raisins, dried figs and dried Iongans were in the ranges of 0.1-462.7, 0.2-247.3, 0.8-10.1,0.2-384.1 and 0.1-89.2 μg kg^-1, respectively. Dried figs （80.0%） had the highest incidence of mycotoxins, followed by dried Iongans （60.0%）, dried jujubes （57.1%）, nuts （43.6%） and raisins （26.7%）. The estimated daily intake （EDI） values of each individual mycotoxin and all of the mycotoxins collectively were calculated by both the deterministic approach （DA） and the probability approach （PA）. For risk characterization, dietary exposure to TCs, ATs and OTA through consumption of nuts and dried fruits according to both approaches, showed no health risk to Chinese adults by exposure to either individual mycotoxins or in combination. To the best of our knowledge, this is the first work in which risk assessment of multimycotoxins is performed, specifically including the emerging ENNs and BEA, in nuts and dried fruits of China.
基金supported by the Young Fund of Shanxi University of Finance and Economics(No.QN-2018002)National Natural Science Foundation of China(No.71774105)the Fund for Shanxi Key Subjects Construction(FSKSC)and Shanxi Repatriate Study Abroad Foundation(No.2016-3)
文摘International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project's NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project's NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making.
