This paper presents a risk-informed data-driven safe control design approach for a class of stochastic uncertain nonlinear discrete-time systems.The nonlinear system is modeled using linear parameter-varying(LPV)syste...This paper presents a risk-informed data-driven safe control design approach for a class of stochastic uncertain nonlinear discrete-time systems.The nonlinear system is modeled using linear parameter-varying(LPV)systems.A model-based probabilistic safe controller is first designed to guarantee probabilisticλ-contractivity(i.e.,stability and invariance)of the LPV system with respect to a given polyhedral safe set.To obviate the requirement of knowing the LPV system model and to bypass identifying its open-loop model,its closed-loop data-based representation is provided in terms of state and scheduling data as well as a decision variable.It is shown that the variance of the closedloop system,as well as the probability of safety satisfaction,depends on the decision variable and the noise covariance.A minimum-variance direct data-driven gain-scheduling safe control design approach is presented next by designing the decision variable such that all possible closed-loop system realizations satisfy safety with the highest confidence level.This minimum-variance approach is a control-oriented learning method since it minimizes the variance of the state of the closed-loop system with respect to the safe set,and thus minimizes the risk of safety violation.Unlike the certainty-equivalent approach that results in a risk-neutral control design,the minimum-variance method leads to a risk-averse control design.It is shown that the presented direct risk-averse learning approach requires weaker data richness conditions than existing indirect learning methods based on system identification and can lead to a lower risk of safety violation.Two simulation examples along with an experimental validation on an autonomous vehicle are provided to show the effectiveness of the presented approach.展开更多
Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequent...Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequential Convex Programming(SFC-SCP)to improve the computation efficiency and reliability of trajectory generation.SFC-SCP combines the front-end convex polyhedron SFC construction and back-end SCP-based trajectory optimization.A Sparse A^(*)Search(SAS)driven SFC construction method is designed to efficiently generate polyhedron SFC according to the geometric relation among obstacles and collision-free waypoints.Via transforming the nonconvex obstacle-avoidance constraints to linear inequality constraints,SFC can mitigate infeasibility of trajectory planning and reduce computation complexity.Then,SCP casts the nonlinear trajectory optimization subject to SFC into convex programming subproblems to decrease the problem complexity.In addition,a convex optimizer based on interior point method is customized,where the search direction is calculated via successive elimination to further improve efficiency.Simulation experiments on dense obstacle scenarios show that SFC-SCP can generate dynamically feasible safe trajectory rapidly.Comparative studies with state-of-the-art SCP-based methods demonstrate the efficiency and reliability merits of SFC-SCP.Besides,the customized convex optimizer outperforms off-the-shelf optimizers in terms of computation time.展开更多
Grasping is one of the most fundamental operations in modern robotics applications.While deep rein-forcement learning(DRL)has demonstrated strong potential in robotics,there is too much emphasis on maximizing the cumu...Grasping is one of the most fundamental operations in modern robotics applications.While deep rein-forcement learning(DRL)has demonstrated strong potential in robotics,there is too much emphasis on maximizing the cumulative reward in executing tasks,and the potential safety risks are often ignored.In this paper,an optimization method based on safe reinforcement learning(Safe RL)is proposed to address the robotic grasping problem under safety constraints.Specifically,considering the obstacle avoidance constraints of the system,the grasping problem of the manipulator is modeled as a Constrained Markov Decision Process(CMDP).The Lagrange multiplier and a dynamic weighted mechanism are introduced into the Proximal Policy Optimization(PPO)framework,leading to the development of the dynamic weighted Lagrange PPO(DWL-PPO)algorithm.The behavior of violating safety constraints is punished while the policy is optimized in this proposed method.In addition,the orientation control of the end-effector is included in the reward function,and a compound reward function adapted to changes in pose is designed.Ultimately,the efficacy and advantages of the suggested method are proved by extensive training and testing in the Pybullet simulator.The results of grasping experiments reveal that the recommended approach provides superior safety and efficiency compared with other advanced RL methods and achieves a good trade-off between model learning and risk aversion.展开更多
Objective:To explore the application effect of bundle management in the safe nursing of patients with autoimmune encephalitis.Methods:Seventy-five patients with autoimmune encephalitis who met the inclusion criteria i...Objective:To explore the application effect of bundle management in the safe nursing of patients with autoimmune encephalitis.Methods:Seventy-five patients with autoimmune encephalitis who met the inclusion criteria in our hospital from January 2024 to June 2024 were randomly divided into two groups:an observation group of 39 patients and a control group of 36 patients.The control group received routine nursing care,while the observation group implemented a bundle management strategy based on routine nursing care.Safety nursing outcomes,clinical symptom improvement time,hospital stay,and neurologic function recovery were observed in both groups.Results:The incidence of adverse events in the observation group was 12.82%,significantly lower than the 33.33%in the control group,with a statistically significant difference(P<0.05).There was no statistically significant difference in restraint usage and ICU transfer rates between the two groups(P>0.05).The clinical symptom improvement time,hospital stay,and neurologic function recovery in the observation group were significantly better than those in the control group,with a statistically significant difference(P<0.05).Conclusion:Through the bundle management model,effective connections can be ensured in various aspects of treatment and rehabilitation for patients with autoimmune encephalitis,providing patients with comprehensive and multi-level nursing services and improving their overall satisfaction and treatment effectiveness.展开更多
Semi-supervised clustering techniques attempt to improve clustering accuracy by utilizing a limited number of labeled data for guidance.This method effectively integrates prior knowledge using pre-labeled data.While s...Semi-supervised clustering techniques attempt to improve clustering accuracy by utilizing a limited number of labeled data for guidance.This method effectively integrates prior knowledge using pre-labeled data.While semi-supervised fuzzy clustering(SSFC)methods leverage limited labeled data to enhance accuracy,they remain highly susceptible to inappropriate or mislabeled prior knowledge,especially in noisy or overlapping datasets where cluster boundaries are ambiguous.To enhance the effectiveness of clustering algorithms,it is essential to leverage labeled data while ensuring the safety of the previous knowledge.Existing solutions,such as the Trusted Safe Semi-Supervised Fuzzy Clustering Method(TS3FCM),struggle with random centroid initialization,fixed neighbor radius formulas,and handling outliers or noise at cluster overlaps.A new framework called Active Safe Semi-Supervised Fuzzy Clustering with Pairwise Constraints Based on Cluster Boundary(AS3FCPC)is proposed in this paper to deal with these problems.It does this by combining pairwise constraints and active learning.AS3FCPC uses active learning to query only the most informative data instances close to the cluster boundaries.It also uses pairwise constraints to enforce the cluster structure,which makes the system more accurate and robust.Extensive test results on diverse datasets,including challenging noisy and overlapping scenarios,demonstrate that AS3FCPC consistently achieves superior performance compared to state-of-the-art methods like TS3FCM and other baselines,especially when the data is noisy and overlaps.This significant improvement underscores AS3FCPC’s potential for reliable and accurate semisupervised fuzzy clustering in complex,real-world applications,particularly by effectively managing mislabeled data and ambiguous cluster boundaries.展开更多
IN the Shanghai Jewish Refugees Museum,a beautiful handbag is waiting for its owner in a display cabinet.The handbag belongs to a Jewish couple.When they sought refuge in Shanghai during World War II,they pawned the h...IN the Shanghai Jewish Refugees Museum,a beautiful handbag is waiting for its owner in a display cabinet.The handbag belongs to a Jewish couple.When they sought refuge in Shanghai during World War II,they pawned the handbag to Jin Wenzhen’s grandfather in exchange for their child’s medical expenses.He lent the couple the cash equivalent of one month’s revenue from his rice shop,but then never saw them again.展开更多
Due to the influence of karst cave development and route selection,the location relationship between concealed karst cave and tunnel is more random.In order to explore the influence rule of karst cave location on the ...Due to the influence of karst cave development and route selection,the location relationship between concealed karst cave and tunnel is more random.In order to explore the influence rule of karst cave location on the minimum safe thickness of water-proof rock mass,a simplified calculation model of water-proof rock mass thickness when the karst cave is located at any location around the tunnel is established,and the influence of multiple factors on the overall stability of water-proof rock mass is considered.Based on the cusp catastrophe theory,the analytical expressions for the safety thickness of waterproof rock mass are derived.Based on the finite difference principle,the analytical expressions of the safety thickness of water-proof rock mass are verified.In order to improve the application range of the analytical formula derived in this paper,the analytical formula is optimized based on the instability principle differences between the simplified calculation model and the elastic compressive bar.The research results show that the necessary condition solution is more applicable and much safer than the sufficient condition solution.Tectonic stress,rock beam length and karst cave water pressure are significantly positively correlated with the safe thickness of the waterproof rock mass.The calculated results of the semioptimized formula and the unoptimized formula are constant values,independent of the karst cave location.While the calculated results of the fully optimized formula are variable values,correlated with the karst cave location,the thickness of the waterproof rock mass gradually decreases as the karst cave location moves from the top of the tunnel to the bottom of the tunnel.The unoptimized formula does not consider the influence of the lateral force of the rock beam,and is not suitable for the working condition with large lateral force,the calculation results of the semi-optimized formula and the fully optimized formula are not very different and are biased to safety,so it can be given priority.展开更多
Against the backdrop of the global push for environmental protection and the reduction of plastic pollution,the research and development of alternatives to daily disposable plastic products such as straws have become ...Against the backdrop of the global push for environmental protection and the reduction of plastic pollution,the research and development of alternatives to daily disposable plastic products such as straws have become a hot topic in the environmental protection field.Traditional plastic straws are difficult to degrade,imposing a severe burden on the environment.Meanwhile,existing alternatives like paper straws and PLA(polylactic acid)straws also have numerous drawbacks.展开更多
Objective: The present research aims to determine if adherence to the Lewinnek safe zone, when exclusively considered, constitutes a pivotal element for ensuring stability in the context of total hip arthroplasty. Thi...Objective: The present research aims to determine if adherence to the Lewinnek safe zone, when exclusively considered, constitutes a pivotal element for ensuring stability in the context of total hip arthroplasty. This is done by examining the acetabular placement in instances of hip dislocation after total hip arthroplasty (THA). Methodology: The authors searched 2653 patient records from 2015 to 2022 looking for patients who had total hip arthroplasty at our facility. For the analysis, 23 patients were culled from 64 individuals who exhibited post-THA dislocations, employing a stringent exclusion criterion, and the resultant acetabular angulation and anteversion were quantified utilizing PEEKMED software (Peek Health S.A., Portugal) upon radiographic evidence. Results: Within the operational timeframe, from the cohort of 2653 subjects, 64 presented with at least a singular incident of displacement. Post-exclusion criterion enforcement, 23 patients were eligible for inclusion. Of these, 10 patients conformed to the safe zone demarcated by Lewinnek for both inclination and anteversion angles, while 13 exhibited deviations from the prescribed anteversion and/or inclination benchmarks. Conclusion: Analysis of the 23 patients reveals that 13 did not confirm to be in the safe zone parameters for anteversion and/or inclination, whereas 10 were within the safe zone as per Lewinnek’s guidelines. This investigative review, corroborated by extant literature, suggests that the isolated consideration of the Lewinnek safe zone does not suffice as a solitary protective factor. It further posits that additional variables are equally critical as acetabular positioning and mandate individual assessment.展开更多
Low visibility conditions,particularly those caused by fog,significantly affect road safety and reduce drivers’ability to see ahead clearly.The conventional approaches used to address this problem primarily rely on i...Low visibility conditions,particularly those caused by fog,significantly affect road safety and reduce drivers’ability to see ahead clearly.The conventional approaches used to address this problem primarily rely on instrument-based and fixed-threshold-based theoretical frameworks,which face challenges in adaptability and demonstrate lower performance under varying environmental conditions.To overcome these challenges,we propose a real-time visibility estimation model that leverages roadside CCTV cameras to monitor and identify visibility levels under different weather conditions.The proposedmethod begins by identifying specific regions of interest(ROI)in the CCTVimages and focuses on extracting specific features such as the number of lines and contours detected within these regions.These features are then provided as an input to the proposed hierarchical clusteringmodel,which classifies them into different visibility levels without the need for predefined rules and threshold values.In the proposed approach,we used two different distance similaritymetrics,namely dynamic time warping(DTW)and Euclidean distance,alongside the proposed hierarchical clustering model and noted its performance in terms of numerous evaluation measures.The proposed model achieved an average accuracy of 97.81%,precision of 91.31%,recall of 91.25%,and F1-score of 91.27% using theDTWdistancemetric.We also conducted experiments for other deep learning(DL)-based models used in the literature and compared their performances with the proposed model.The experimental results demonstrate that the proposedmodel ismore adaptable and consistent compared to themethods used in the literature.The proposedmethod provides drivers real-time and accurate visibility information and enhances road safety during low visibility conditions.展开更多
With the civilization and modernization of human society,occupational health has emerged as a fundamental goal of social justice,as highlighted in the United Nations'Sustainable Development Goals(SDGs)since 2016.S...With the civilization and modernization of human society,occupational health has emerged as a fundamental goal of social justice,as highlighted in the United Nations'Sustainable Development Goals(SDGs)since 2016.Specifically,"SDG Goal 1:No Poverty","SDG 3:Good Health and Well-being",and"SDG 8:Decent Work and Economic Growth",are interconnected with other SDGs to support the pursuit of occupational health.展开更多
A Bayesian method is used to evaluate the component safety failure model parameter of the safe arming system of an air faced missile in flight. It was proved that Bayes estimation of the model parameter is coinciden...A Bayesian method is used to evaluate the component safety failure model parameter of the safe arming system of an air faced missile in flight. It was proved that Bayes estimation of the model parameter is coincident with the physical explanation of the prior probability density distribution of the random parameter.展开更多
After summarizing researches on domestic and foreign tourism safety,it was found that there were few research results on mountainous tourism safety,especially tourism safety and tourism safety guarantee system of high...After summarizing researches on domestic and foreign tourism safety,it was found that there were few research results on mountainous tourism safety,especially tourism safety and tourism safety guarantee system of high and higher mountains with high risk.The paper had concluded hidden dangers and sources of safe accidents of mountainous tourism,and studied tourism safety guarantee system of high and higher mountains.Furthermore,it proposed that tourism safety guarantee system was composed of tourism safety policies and regulations,tourism precaution,tourism safety control,tourism safety rescue and tourism insurance;and finally pointed out components of each factor.展开更多
Phosphorus is an essential element in agricultural production and chemical industry. However, since the risk of casualties and economic loss by mining accidents, the application of clean and safe production in phospho...Phosphorus is an essential element in agricultural production and chemical industry. However, since the risk of casualties and economic loss by mining accidents, the application of clean and safe production in phosphorus mines encounters great challenges. For this purpose, a man-machine-environment system composed of evaluation indexes was established, and the grading standards of indexes were defined. Firstly, the measurements of 39 qualitative indexes were obtained through the survey data. According to the measured values of 31 quantitative indexes, the measurements of quantitative indexes were calculated by linear measurement function(LM) and other three functions. Then the singleindex measurement evaluation matrixes were established. Secondly, the entropy weight method was used to determine the weights of each index directly. The analytic hierarchy process(AHP) was also applied to calculate the weights of index and index factor hierarchies after the established hierarchical model. The weights of system hierarchies were given by the grid-based fuzzy Borda method(GFB). The comprehensive weights were determined by the combination method of AHP and GFB(CAG). Furthermore, the multi-index comprehensive measurement evaluation vectors were obtained.Thirdly, the vectors were evaluated by the credible degree recognition(CDR) and the maximum membership(TMM)criteria. Based on the above functions, methods, and criteria, 16 combination evaluation methods were recommended.Finally, the clean and safe production grade of Kaiyang phosphate mine in China was evaluated. The results show that the LM-CAG-CDR is the most reasonable method, which can not only determine the clean and safe production grade of phosphorus mines, but also improve the development level of clean and safe mining of phosphorus mines for guidance.In addition, some beneficial suggestions and measures were also proposed to advance the clean and safe production grade of Kaiyang phosphorus mine.展开更多
Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only syste...Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only system parameters, such as configuration, hazard rate, coverage, repair rate, etc. along with periodic proof-tests （or inspection）. Not considering demand rate will give a pessimistic safety estimate for an application with low demand rate such as nuclear power plants, chemical plants, etc. In this paper, a basic model of IEC 61508 is used. The basic model is extended to incorporate process demand and behavior of electronic- and/or computer-based system following diagnosis or proof-test. A new safety index, probability of failure on actual demand （PFAD） based on extended model and demand rate is proposed. Periodic proof-test makes the model semi-Markovian, so a piece-wise continuous time Markov chain （CTMC） based method is used to derive mean state probabilities of elementary or aggregated state. Method to determine probability of failure on demand （PFD） （IEC 61508） and PFAD based on these state probabilities are described. In example, safety indices of PFD and PFAD are compared.展开更多
This paper considers the dynamical behavior of a Duffing-Mathieu type system with a cubic single-well potential during the principal parametric resonance. Both the cases of constant and time-dependent excitation ampli...This paper considers the dynamical behavior of a Duffing-Mathieu type system with a cubic single-well potential during the principal parametric resonance. Both the cases of constant and time-dependent excitation amplitude are used to observe the variation of the extent and the rate of the erosion in safe basins. It is evident that the appearance of fractal basin boundaries heralds the onset of the losing of structural integrity. The minimum value of control parameter to prevent the basin from erosion is given along with the excitation amplitude varying. The results show the time-dependence of excitation amplitude can be used to control the extent and the rate of the erosion and delay the first occurrence of heteroclinic tangency.展开更多
Oil and gas production systems have the characteristics of high operation and maintenance risk and great accident influence.With the deep integration of informationization and industrialization,the development directio...Oil and gas production systems have the characteristics of high operation and maintenance risk and great accident influence.With the deep integration of informationization and industrialization,the development direction and necessary choice of the oil and gas industry is to develop the oil and gas production system into the interconnected,multi-domain interactive cyber-physical intelligent system.In order to avoid or reduce the complex,diverse and potentially unknown safety risks in the process of oil and gas production,improve the safety and reliability of oil and gas production system and increase the production efficiency,this paper analyzes the safety problems occurring in the intelligentization process of oil and gas production system and constructs a system from the perspective of operation and maintenance based on key elements of intelligent safe operation and maintenance technology,combined with the typical production scenarios in the oil and gas production industry.And the following research results are obtained.First,the connotation of intelligent safe operation and maintenance technology is clarified,the key elements and existing problems and challenges of intelligent safe operation and maintenance technology are analyzed,and the“1-2-3-4-5-6”intelligent safe operation and maintenance technology system of oil and gas production system is constructed,which empowers six key technologies with key elements of oil and gas production to realize the essential safety of oil and gas production system.Second,the intelligent safe operation and maintenance technology actively promotes the application and implementation of condition monitoring,health management,risk assessment,intelligent early warning technologies in typical production scenarios such as drilling and extraction,storage and transportation,refining and chemical industry in up,middle and down streams of oil and gas production.Third,in view of the characteristics of oil and gas production system under digital transformation,it is proposed to develop the intelligent safe operation and maintenance technology with the functions of intelligent decision-making,active prevention and comprehensive safety in the future to help the safe construction in thefield of oil and gas production and promote the safe and healthy development of the oil and gas industry.In conclusion,the research on intelligent safe operation and maintenance technology system of oil and gas production system is conducive to the safe construction in thefield of oil and gas production,which will not only provide technical support for the realization of trouble-free oil and gas production system,but also provide reference for the intelligent development of the world oil and gas industry.展开更多
Background: The number of older people is increasing. Many of them expect to maintain a rich social life and to continue driving at an older age. Objective: The present study investigates the mechanisms behind self-re...Background: The number of older people is increasing. Many of them expect to maintain a rich social life and to continue driving at an older age. Objective: The present study investigates the mechanisms behind self-regulation and driving cessation in order to suggest development of support systems to prolong older drivers’ safe mobility. Method: Three focus groups were conducted with 19 older active drivers aged 65+ who were divided according to annual mileage driven. Results: A content analysis revealed broad self-regulatory behaviour as already reported in the literature, e.g., avoiding driving at rush hour and at night. The participants also reported difficulty in finding the way to their final destination and an increasing need to plan their travelling. Co-piloting was a behaviour applied by couples to cope with difficulties encountered in traffic. A large part of the discussion was focused on emerging feelings of stress, anxiety and fear when driving in recent years, a feeling induced by external factors e.g., other road users’ behaviour, traffic density or high speed. Apart from health problems, high levels of stress could explain driving cessation, especially for women. An increased feeling of safety and comfort could be achieved by an increased use of support systems specifically designed to respond to older drivers’ needs. Conclusion: Support systems for older drivers should increase comfort and decrease their stress levels. New systems, such as co-pilot function and more developed Global Positioning System (GPS) supporting of the entire travel from door to door, should be developed to respond to the market needs.展开更多
The digestibility of cadmium(Cd)in brown rice is directly related to amino acid metabolism in rice and human health.In our field study,three kinds of alkaline calcium-rich soil inorganic amendments(SIAs)at three dosag...The digestibility of cadmium(Cd)in brown rice is directly related to amino acid metabolism in rice and human health.In our field study,three kinds of alkaline calcium-rich soil inorganic amendments(SIAs)at three dosages were applied to produce safe rice and improve the quality of rice in Cd-contaminated paddy.With the increased application of SIA,Cd content in iron plaque on rice root significantly increased,the transfer of Cd from rice root to grain significantly decreased,and then Cd content in brown rice decreased synchronously.The vitro digestibility of Cd in brown rice was estimated by a physiologically based extraction test.Results showed that more than 70%of Cd in brown rice could be digested by simulated gastrointestinal juice.Based on the total and digestible Cd contents in brown rice to evaluate the health risk,the application of 2.25 ton SIA/ha could produce safe rice in acidic slightly Cd-contaminated paddy soils.The amino acids(AAs)in brown rice were determined by high-performance liquid chromatography.The contents of 5 key AAs(KAAs)that actively respond to environmental changes increased significantly with the increased application of SIA.The structural equation model indicated that KAAs could be affected by the Cd translocation capacity from rice root to grain,and consequently altered the ratio of indigestible Cd in brown rice.The formation of indigestible KAAs-Cd complexes by combining KAAs(phenylalanine,leucine,histidine,glutamine,and asparagine)with Cd in brown rice could be considered a potential mechanism for reducing the digestibility of Cd.展开更多
In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost ef...In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost efficiency,a quantity of research has been conducted on the commercial application of LIBs.However,it is difficult to achieve satisfying safety and cycling performance simultaneously.There may be thermal runaway(TR),external impact,overcharge and overdischarge in the process of battery abuse,which makes the safety problem of LIBs more prominent.In this review,we summarize recent progress in the smart safety materials design towards the goal of preventing TR of LIBs reversibly from different abuse conditions.Benefiting from smart responsive materials and novel structural design,the safety of LIBs can be improved a lot.We expect to provide a comprehensive reference for the development of smart and safe lithium-based battery materials.展开更多
基金supported in part by the Department of Navy award (N00014-22-1-2159)the National Science Foundation under award (ECCS-2227311)。
文摘This paper presents a risk-informed data-driven safe control design approach for a class of stochastic uncertain nonlinear discrete-time systems.The nonlinear system is modeled using linear parameter-varying(LPV)systems.A model-based probabilistic safe controller is first designed to guarantee probabilisticλ-contractivity(i.e.,stability and invariance)of the LPV system with respect to a given polyhedral safe set.To obviate the requirement of knowing the LPV system model and to bypass identifying its open-loop model,its closed-loop data-based representation is provided in terms of state and scheduling data as well as a decision variable.It is shown that the variance of the closedloop system,as well as the probability of safety satisfaction,depends on the decision variable and the noise covariance.A minimum-variance direct data-driven gain-scheduling safe control design approach is presented next by designing the decision variable such that all possible closed-loop system realizations satisfy safety with the highest confidence level.This minimum-variance approach is a control-oriented learning method since it minimizes the variance of the state of the closed-loop system with respect to the safe set,and thus minimizes the risk of safety violation.Unlike the certainty-equivalent approach that results in a risk-neutral control design,the minimum-variance method leads to a risk-averse control design.It is shown that the presented direct risk-averse learning approach requires weaker data richness conditions than existing indirect learning methods based on system identification and can lead to a lower risk of safety violation.Two simulation examples along with an experimental validation on an autonomous vehicle are provided to show the effectiveness of the presented approach.
基金supported by the National Natural Science Foundation of China(No.62203256)。
文摘Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequential Convex Programming(SFC-SCP)to improve the computation efficiency and reliability of trajectory generation.SFC-SCP combines the front-end convex polyhedron SFC construction and back-end SCP-based trajectory optimization.A Sparse A^(*)Search(SAS)driven SFC construction method is designed to efficiently generate polyhedron SFC according to the geometric relation among obstacles and collision-free waypoints.Via transforming the nonconvex obstacle-avoidance constraints to linear inequality constraints,SFC can mitigate infeasibility of trajectory planning and reduce computation complexity.Then,SCP casts the nonlinear trajectory optimization subject to SFC into convex programming subproblems to decrease the problem complexity.In addition,a convex optimizer based on interior point method is customized,where the search direction is calculated via successive elimination to further improve efficiency.Simulation experiments on dense obstacle scenarios show that SFC-SCP can generate dynamically feasible safe trajectory rapidly.Comparative studies with state-of-the-art SCP-based methods demonstrate the efficiency and reliability merits of SFC-SCP.Besides,the customized convex optimizer outperforms off-the-shelf optimizers in terms of computation time.
文摘Grasping is one of the most fundamental operations in modern robotics applications.While deep rein-forcement learning(DRL)has demonstrated strong potential in robotics,there is too much emphasis on maximizing the cumulative reward in executing tasks,and the potential safety risks are often ignored.In this paper,an optimization method based on safe reinforcement learning(Safe RL)is proposed to address the robotic grasping problem under safety constraints.Specifically,considering the obstacle avoidance constraints of the system,the grasping problem of the manipulator is modeled as a Constrained Markov Decision Process(CMDP).The Lagrange multiplier and a dynamic weighted mechanism are introduced into the Proximal Policy Optimization(PPO)framework,leading to the development of the dynamic weighted Lagrange PPO(DWL-PPO)algorithm.The behavior of violating safety constraints is punished while the policy is optimized in this proposed method.In addition,the orientation control of the end-effector is included in the reward function,and a compound reward function adapted to changes in pose is designed.Ultimately,the efficacy and advantages of the suggested method are proved by extensive training and testing in the Pybullet simulator.The results of grasping experiments reveal that the recommended approach provides superior safety and efficiency compared with other advanced RL methods and achieves a good trade-off between model learning and risk aversion.
文摘Objective:To explore the application effect of bundle management in the safe nursing of patients with autoimmune encephalitis.Methods:Seventy-five patients with autoimmune encephalitis who met the inclusion criteria in our hospital from January 2024 to June 2024 were randomly divided into two groups:an observation group of 39 patients and a control group of 36 patients.The control group received routine nursing care,while the observation group implemented a bundle management strategy based on routine nursing care.Safety nursing outcomes,clinical symptom improvement time,hospital stay,and neurologic function recovery were observed in both groups.Results:The incidence of adverse events in the observation group was 12.82%,significantly lower than the 33.33%in the control group,with a statistically significant difference(P<0.05).There was no statistically significant difference in restraint usage and ICU transfer rates between the two groups(P>0.05).The clinical symptom improvement time,hospital stay,and neurologic function recovery in the observation group were significantly better than those in the control group,with a statistically significant difference(P<0.05).Conclusion:Through the bundle management model,effective connections can be ensured in various aspects of treatment and rehabilitation for patients with autoimmune encephalitis,providing patients with comprehensive and multi-level nursing services and improving their overall satisfaction and treatment effectiveness.
文摘Semi-supervised clustering techniques attempt to improve clustering accuracy by utilizing a limited number of labeled data for guidance.This method effectively integrates prior knowledge using pre-labeled data.While semi-supervised fuzzy clustering(SSFC)methods leverage limited labeled data to enhance accuracy,they remain highly susceptible to inappropriate or mislabeled prior knowledge,especially in noisy or overlapping datasets where cluster boundaries are ambiguous.To enhance the effectiveness of clustering algorithms,it is essential to leverage labeled data while ensuring the safety of the previous knowledge.Existing solutions,such as the Trusted Safe Semi-Supervised Fuzzy Clustering Method(TS3FCM),struggle with random centroid initialization,fixed neighbor radius formulas,and handling outliers or noise at cluster overlaps.A new framework called Active Safe Semi-Supervised Fuzzy Clustering with Pairwise Constraints Based on Cluster Boundary(AS3FCPC)is proposed in this paper to deal with these problems.It does this by combining pairwise constraints and active learning.AS3FCPC uses active learning to query only the most informative data instances close to the cluster boundaries.It also uses pairwise constraints to enforce the cluster structure,which makes the system more accurate and robust.Extensive test results on diverse datasets,including challenging noisy and overlapping scenarios,demonstrate that AS3FCPC consistently achieves superior performance compared to state-of-the-art methods like TS3FCM and other baselines,especially when the data is noisy and overlaps.This significant improvement underscores AS3FCPC’s potential for reliable and accurate semisupervised fuzzy clustering in complex,real-world applications,particularly by effectively managing mislabeled data and ambiguous cluster boundaries.
文摘IN the Shanghai Jewish Refugees Museum,a beautiful handbag is waiting for its owner in a display cabinet.The handbag belongs to a Jewish couple.When they sought refuge in Shanghai during World War II,they pawned the handbag to Jin Wenzhen’s grandfather in exchange for their child’s medical expenses.He lent the couple the cash equivalent of one month’s revenue from his rice shop,but then never saw them again.
基金jointly funded by the guangxi Science and Technology Base and Talent Project(AD23026104)the Key Research and Development Program Project in Guangxi(AB23026121)。
文摘Due to the influence of karst cave development and route selection,the location relationship between concealed karst cave and tunnel is more random.In order to explore the influence rule of karst cave location on the minimum safe thickness of water-proof rock mass,a simplified calculation model of water-proof rock mass thickness when the karst cave is located at any location around the tunnel is established,and the influence of multiple factors on the overall stability of water-proof rock mass is considered.Based on the cusp catastrophe theory,the analytical expressions for the safety thickness of waterproof rock mass are derived.Based on the finite difference principle,the analytical expressions of the safety thickness of water-proof rock mass are verified.In order to improve the application range of the analytical formula derived in this paper,the analytical formula is optimized based on the instability principle differences between the simplified calculation model and the elastic compressive bar.The research results show that the necessary condition solution is more applicable and much safer than the sufficient condition solution.Tectonic stress,rock beam length and karst cave water pressure are significantly positively correlated with the safe thickness of the waterproof rock mass.The calculated results of the semioptimized formula and the unoptimized formula are constant values,independent of the karst cave location.While the calculated results of the fully optimized formula are variable values,correlated with the karst cave location,the thickness of the waterproof rock mass gradually decreases as the karst cave location moves from the top of the tunnel to the bottom of the tunnel.The unoptimized formula does not consider the influence of the lateral force of the rock beam,and is not suitable for the working condition with large lateral force,the calculation results of the semi-optimized formula and the fully optimized formula are not very different and are biased to safety,so it can be given priority.
文摘Against the backdrop of the global push for environmental protection and the reduction of plastic pollution,the research and development of alternatives to daily disposable plastic products such as straws have become a hot topic in the environmental protection field.Traditional plastic straws are difficult to degrade,imposing a severe burden on the environment.Meanwhile,existing alternatives like paper straws and PLA(polylactic acid)straws also have numerous drawbacks.
文摘Objective: The present research aims to determine if adherence to the Lewinnek safe zone, when exclusively considered, constitutes a pivotal element for ensuring stability in the context of total hip arthroplasty. This is done by examining the acetabular placement in instances of hip dislocation after total hip arthroplasty (THA). Methodology: The authors searched 2653 patient records from 2015 to 2022 looking for patients who had total hip arthroplasty at our facility. For the analysis, 23 patients were culled from 64 individuals who exhibited post-THA dislocations, employing a stringent exclusion criterion, and the resultant acetabular angulation and anteversion were quantified utilizing PEEKMED software (Peek Health S.A., Portugal) upon radiographic evidence. Results: Within the operational timeframe, from the cohort of 2653 subjects, 64 presented with at least a singular incident of displacement. Post-exclusion criterion enforcement, 23 patients were eligible for inclusion. Of these, 10 patients conformed to the safe zone demarcated by Lewinnek for both inclination and anteversion angles, while 13 exhibited deviations from the prescribed anteversion and/or inclination benchmarks. Conclusion: Analysis of the 23 patients reveals that 13 did not confirm to be in the safe zone parameters for anteversion and/or inclination, whereas 10 were within the safe zone as per Lewinnek’s guidelines. This investigative review, corroborated by extant literature, suggests that the isolated consideration of the Lewinnek safe zone does not suffice as a solitary protective factor. It further posits that additional variables are equally critical as acetabular positioning and mandate individual assessment.
文摘Low visibility conditions,particularly those caused by fog,significantly affect road safety and reduce drivers’ability to see ahead clearly.The conventional approaches used to address this problem primarily rely on instrument-based and fixed-threshold-based theoretical frameworks,which face challenges in adaptability and demonstrate lower performance under varying environmental conditions.To overcome these challenges,we propose a real-time visibility estimation model that leverages roadside CCTV cameras to monitor and identify visibility levels under different weather conditions.The proposedmethod begins by identifying specific regions of interest(ROI)in the CCTVimages and focuses on extracting specific features such as the number of lines and contours detected within these regions.These features are then provided as an input to the proposed hierarchical clusteringmodel,which classifies them into different visibility levels without the need for predefined rules and threshold values.In the proposed approach,we used two different distance similaritymetrics,namely dynamic time warping(DTW)and Euclidean distance,alongside the proposed hierarchical clustering model and noted its performance in terms of numerous evaluation measures.The proposed model achieved an average accuracy of 97.81%,precision of 91.31%,recall of 91.25%,and F1-score of 91.27% using theDTWdistancemetric.We also conducted experiments for other deep learning(DL)-based models used in the literature and compared their performances with the proposed model.The experimental results demonstrate that the proposedmodel ismore adaptable and consistent compared to themethods used in the literature.The proposedmethod provides drivers real-time and accurate visibility information and enhances road safety during low visibility conditions.
文摘With the civilization and modernization of human society,occupational health has emerged as a fundamental goal of social justice,as highlighted in the United Nations'Sustainable Development Goals(SDGs)since 2016.Specifically,"SDG Goal 1:No Poverty","SDG 3:Good Health and Well-being",and"SDG 8:Decent Work and Economic Growth",are interconnected with other SDGs to support the pursuit of occupational health.
文摘A Bayesian method is used to evaluate the component safety failure model parameter of the safe arming system of an air faced missile in flight. It was proved that Bayes estimation of the model parameter is coincident with the physical explanation of the prior probability density distribution of the random parameter.
基金Supported by Science and Technology Support Project of Sichuan Province(2009SZ0067)Key Research Subject of Soft Science Research Project of Sichuan Province(2009ZR0103)~~
文摘After summarizing researches on domestic and foreign tourism safety,it was found that there were few research results on mountainous tourism safety,especially tourism safety and tourism safety guarantee system of high and higher mountains with high risk.The paper had concluded hidden dangers and sources of safe accidents of mountainous tourism,and studied tourism safety guarantee system of high and higher mountains.Furthermore,it proposed that tourism safety guarantee system was composed of tourism safety policies and regulations,tourism precaution,tourism safety control,tourism safety rescue and tourism insurance;and finally pointed out components of each factor.
基金Project(51974362) supported by the National Natural Science Foundation of ChinaProject(2282020cxqd055) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2021-QYC-10050-25631) supported by the Department of Emergency Management of Hunan Province,China。
文摘Phosphorus is an essential element in agricultural production and chemical industry. However, since the risk of casualties and economic loss by mining accidents, the application of clean and safe production in phosphorus mines encounters great challenges. For this purpose, a man-machine-environment system composed of evaluation indexes was established, and the grading standards of indexes were defined. Firstly, the measurements of 39 qualitative indexes were obtained through the survey data. According to the measured values of 31 quantitative indexes, the measurements of quantitative indexes were calculated by linear measurement function(LM) and other three functions. Then the singleindex measurement evaluation matrixes were established. Secondly, the entropy weight method was used to determine the weights of each index directly. The analytic hierarchy process(AHP) was also applied to calculate the weights of index and index factor hierarchies after the established hierarchical model. The weights of system hierarchies were given by the grid-based fuzzy Borda method(GFB). The comprehensive weights were determined by the combination method of AHP and GFB(CAG). Furthermore, the multi-index comprehensive measurement evaluation vectors were obtained.Thirdly, the vectors were evaluated by the credible degree recognition(CDR) and the maximum membership(TMM)criteria. Based on the above functions, methods, and criteria, 16 combination evaluation methods were recommended.Finally, the clean and safe production grade of Kaiyang phosphate mine in China was evaluated. The results show that the LM-CAG-CDR is the most reasonable method, which can not only determine the clean and safe production grade of phosphorus mines, but also improve the development level of clean and safe mining of phosphorus mines for guidance.In addition, some beneficial suggestions and measures were also proposed to advance the clean and safe production grade of Kaiyang phosphorus mine.
文摘Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only system parameters, such as configuration, hazard rate, coverage, repair rate, etc. along with periodic proof-tests （or inspection）. Not considering demand rate will give a pessimistic safety estimate for an application with low demand rate such as nuclear power plants, chemical plants, etc. In this paper, a basic model of IEC 61508 is used. The basic model is extended to incorporate process demand and behavior of electronic- and/or computer-based system following diagnosis or proof-test. A new safety index, probability of failure on actual demand （PFAD） based on extended model and demand rate is proposed. Periodic proof-test makes the model semi-Markovian, so a piece-wise continuous time Markov chain （CTMC） based method is used to derive mean state probabilities of elementary or aggregated state. Method to determine probability of failure on demand （PFD） （IEC 61508） and PFAD based on these state probabilities are described. In example, safety indices of PFD and PFAD are compared.
基金the National Science Foundation of ChinaPSF of China
文摘This paper considers the dynamical behavior of a Duffing-Mathieu type system with a cubic single-well potential during the principal parametric resonance. Both the cases of constant and time-dependent excitation amplitude are used to observe the variation of the extent and the rate of the erosion in safe basins. It is evident that the appearance of fractal basin boundaries heralds the onset of the losing of structural integrity. The minimum value of control parameter to prevent the basin from erosion is given along with the excitation amplitude varying. The results show the time-dependence of excitation amplitude can be used to control the extent and the rate of the erosion and delay the first occurrence of heteroclinic tangency.
基金supported by the Key Program of National Natural Science Foundation of China“Research on risk formation mechanism and control method of oil&gas storage and transportation system from the perspective of cyber-physics”(No:52234007).
文摘Oil and gas production systems have the characteristics of high operation and maintenance risk and great accident influence.With the deep integration of informationization and industrialization,the development direction and necessary choice of the oil and gas industry is to develop the oil and gas production system into the interconnected,multi-domain interactive cyber-physical intelligent system.In order to avoid or reduce the complex,diverse and potentially unknown safety risks in the process of oil and gas production,improve the safety and reliability of oil and gas production system and increase the production efficiency,this paper analyzes the safety problems occurring in the intelligentization process of oil and gas production system and constructs a system from the perspective of operation and maintenance based on key elements of intelligent safe operation and maintenance technology,combined with the typical production scenarios in the oil and gas production industry.And the following research results are obtained.First,the connotation of intelligent safe operation and maintenance technology is clarified,the key elements and existing problems and challenges of intelligent safe operation and maintenance technology are analyzed,and the“1-2-3-4-5-6”intelligent safe operation and maintenance technology system of oil and gas production system is constructed,which empowers six key technologies with key elements of oil and gas production to realize the essential safety of oil and gas production system.Second,the intelligent safe operation and maintenance technology actively promotes the application and implementation of condition monitoring,health management,risk assessment,intelligent early warning technologies in typical production scenarios such as drilling and extraction,storage and transportation,refining and chemical industry in up,middle and down streams of oil and gas production.Third,in view of the characteristics of oil and gas production system under digital transformation,it is proposed to develop the intelligent safe operation and maintenance technology with the functions of intelligent decision-making,active prevention and comprehensive safety in the future to help the safe construction in thefield of oil and gas production and promote the safe and healthy development of the oil and gas industry.In conclusion,the research on intelligent safe operation and maintenance technology system of oil and gas production system is conducive to the safe construction in thefield of oil and gas production,which will not only provide technical support for the realization of trouble-free oil and gas production system,but also provide reference for the intelligent development of the world oil and gas industry.
基金We acknowledge SAFER,Vehicle and Traffic Safety Centre at Chalmers,Gothenburg,Sweden,for funding this researchthe participants from the pensioner or-ganisations PRO and SPF in Jönköping,Sweden.
文摘Background: The number of older people is increasing. Many of them expect to maintain a rich social life and to continue driving at an older age. Objective: The present study investigates the mechanisms behind self-regulation and driving cessation in order to suggest development of support systems to prolong older drivers’ safe mobility. Method: Three focus groups were conducted with 19 older active drivers aged 65+ who were divided according to annual mileage driven. Results: A content analysis revealed broad self-regulatory behaviour as already reported in the literature, e.g., avoiding driving at rush hour and at night. The participants also reported difficulty in finding the way to their final destination and an increasing need to plan their travelling. Co-piloting was a behaviour applied by couples to cope with difficulties encountered in traffic. A large part of the discussion was focused on emerging feelings of stress, anxiety and fear when driving in recent years, a feeling induced by external factors e.g., other road users’ behaviour, traffic density or high speed. Apart from health problems, high levels of stress could explain driving cessation, especially for women. An increased feeling of safety and comfort could be achieved by an increased use of support systems specifically designed to respond to older drivers’ needs. Conclusion: Support systems for older drivers should increase comfort and decrease their stress levels. New systems, such as co-pilot function and more developed Global Positioning System (GPS) supporting of the entire travel from door to door, should be developed to respond to the market needs.
基金supported by the National Key R&D Program of China (No.2019YFC1803704)。
文摘The digestibility of cadmium(Cd)in brown rice is directly related to amino acid metabolism in rice and human health.In our field study,three kinds of alkaline calcium-rich soil inorganic amendments(SIAs)at three dosages were applied to produce safe rice and improve the quality of rice in Cd-contaminated paddy.With the increased application of SIA,Cd content in iron plaque on rice root significantly increased,the transfer of Cd from rice root to grain significantly decreased,and then Cd content in brown rice decreased synchronously.The vitro digestibility of Cd in brown rice was estimated by a physiologically based extraction test.Results showed that more than 70%of Cd in brown rice could be digested by simulated gastrointestinal juice.Based on the total and digestible Cd contents in brown rice to evaluate the health risk,the application of 2.25 ton SIA/ha could produce safe rice in acidic slightly Cd-contaminated paddy soils.The amino acids(AAs)in brown rice were determined by high-performance liquid chromatography.The contents of 5 key AAs(KAAs)that actively respond to environmental changes increased significantly with the increased application of SIA.The structural equation model indicated that KAAs could be affected by the Cd translocation capacity from rice root to grain,and consequently altered the ratio of indigestible Cd in brown rice.The formation of indigestible KAAs-Cd complexes by combining KAAs(phenylalanine,leucine,histidine,glutamine,and asparagine)with Cd in brown rice could be considered a potential mechanism for reducing the digestibility of Cd.
基金support by,National Key Research and Development Program(2023YFB2503700 and 2023YFC3008804)the Beijing Municipal Science&Technology Commission No.Z231100006123003+1 种基金the National Science Foundation of China(22071133)the Beijing Natural Science Foundation(No.Z220020).
文摘In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost efficiency,a quantity of research has been conducted on the commercial application of LIBs.However,it is difficult to achieve satisfying safety and cycling performance simultaneously.There may be thermal runaway(TR),external impact,overcharge and overdischarge in the process of battery abuse,which makes the safety problem of LIBs more prominent.In this review,we summarize recent progress in the smart safety materials design towards the goal of preventing TR of LIBs reversibly from different abuse conditions.Benefiting from smart responsive materials and novel structural design,the safety of LIBs can be improved a lot.We expect to provide a comprehensive reference for the development of smart and safe lithium-based battery materials.
