The maintenance of safety and dependability in rail and road embankments is of utmost importance in order to facilitate the smooth operation of transportation networks.This study introduces a comprehensive methodology...The maintenance of safety and dependability in rail and road embankments is of utmost importance in order to facilitate the smooth operation of transportation networks.This study introduces a comprehensive methodology for soil slope stability evaluation,employing Monte Carlo Simulation(MCS)and Subset Simulation(SS)with the"UPSS 3.0 Add-in"in MS-Excel.Focused on an 11.693-meter embankment with a soil slope(inclination ratio of 2H:1V),the investigation considers earthquake coefficients(kh)and pore water pressure ratios(ru)following Indian zoning requirements.The chance of slope failure showed a considerable increase as the Coefficient of Variation(COV),seismic coefficients(kh),and pore water pressure ratios(ru)experienced an escalation.The SS approach showed exceptional efficacy in calculating odds of failure that are notably low.Within computational modeling,the study optimized the worst-case scenario using ANFIS-GA,ANFIS-GWO,ANFIS-PSO,and ANFIS-BBO models.The ANFIS-PSO model exhibits exceptional accuracy(training R2=0.9011,RMSE=0.0549;testing R2=0.8968,RMSE=0.0615),emerging as the most promising.This study highlights the significance of conducting thorough risk assessments and offers practical insights into evaluating and improving the stability of soil slopes in transportation infrastructure.These findings contribute to the enhancement of safety and reliability in real-world situations.展开更多
Aimed at the problem of the low computational efficiency of the existing urethral-valve reliability analysis,an efficient reliability analysis method of the wireless energy-transmitting urethral-valve(WETUV)was propos...Aimed at the problem of the low computational efficiency of the existing urethral-valve reliability analysis,an efficient reliability analysis method of the wireless energy-transmitting urethral-valve(WETUV)was proposed.The method is called FTA-AK-SS,based on the active learning Kriging(AK)model,subset simulation(SS)algorithm,and fault tree analysis(FTA).According to the principle of FTA,we established the fault tree model of the WETUV to determine its minimum cut set and bottom events.Then we defined the random variables affecting its reliability.The U learning function was used to selectively add the sample points of random variables to update the initial Kriging surrogate model.At the same time,combined with the SS algorithm,the reliability and sensitivity analyses of the WETUV were realized.The result shows that compared with the traditional Monte Carlo simulation and FTA-Kriging-SS methods,the proposed method significantly improves the calculation efficiency of the WETUV under the premise of ensuring calculation accuracy.The reliability of the WETUV is greatly affected by the rubber pad’s aging,the receiver coil’s corrosion,and the position deviation.This study can provide a new way to realize a high-efficiency reliability calculation and analysis for urethral valves.展开更多
The response of the train–bridge system has an obvious random behavior.A high traffic density and a long maintenance period of a track will result in a substantial increase in the number of trains running on a bridge...The response of the train–bridge system has an obvious random behavior.A high traffic density and a long maintenance period of a track will result in a substantial increase in the number of trains running on a bridge,and there is small likelihood that the maximum responses of the train and bridge happen in the total maintenance period of the track.Firstly,the coupling model of train–bridge systems is reviewed.Then,an ensemble method is presented,which can estimate the small probabilities of a dynamic system with stochastic excitations.The main idea of the ensemble method is to use the NARX(nonlinear autoregressive with exogenous input)model to replace the physical model and apply subset simulation with splitting to obtain the extreme distribution.Finally,the efficiency of the suggested method is compared with the direct Monte Carlo simulation method,and the probability exceedance of train responses under the vertical track irregularity is discussed.The results show that when the small probability of train responses under vertical track irregularity is estimated,the ensemble method can reduce both the calculation time of a single sample and the required number of samples.展开更多
Quasi-ellipsoidal gear transmission mechanism, which is the newest transmission mechanism used for robot flexible wrist at present, has simple structure, light weight,small dimension, high sensitivity and can accurate...Quasi-ellipsoidal gear transmission mechanism, which is the newest transmission mechanism used for robot flexible wrist at present, has simple structure, light weight,small dimension, high sensitivity and can accurately carry out the motion transmission in all-direction. It is a new type of transmission used for robot flexible wrist at present. Different from ordinary transmission mechanisms it is a spatial mesh with double DOF. Its design is complicated, and there are many approximate treatments in checking interference of flank and distribution of teeth. The purpose of this paper is to verify the reliability of the design by means of computer simulation.展开更多
The design of a pixel processor of a real-time CIG (Computer Image Generation) system is summarized. The system has been brought into use. In order to adopt ASIC (Application-Specific integrated Circuit) technology in...The design of a pixel processor of a real-time CIG (Computer Image Generation) system is summarized. The system has been brought into use. In order to adopt ASIC (Application-Specific integrated Circuit) technology in the design of the new system, the VHDL (Very high speed integrated circuit Hardware Description Language) is used and a re-design and simulation strategy is planed.展开更多
This paper deals with identification of subset autoregressive time series model. A simulated annealing based on approach for deter min ing the optimal subset of regression terms included in the subset autogressive m...This paper deals with identification of subset autoregressive time series model. A simulated annealing based on approach for deter min ing the optimal subset of regression terms included in the subset autogressive model is introduced. Numerical examples are given to show the effectiveness of the proposed algorithm.展开更多
The effect of refined precipitations and dispersed phases on the toughness of SS400 steel was investigated by rapid tempering with thermomechanical simulation tester, and the electromagnetic induction rapid tempering ...The effect of refined precipitations and dispersed phases on the toughness of SS400 steel was investigated by rapid tempering with thermomechanical simulation tester, and the electromagnetic induction rapid tempering process was simulated. The conventional tempering and rapid tempering process were proceeded respectively, and both samples were quenched in 10~ of agitated iced brine. The tempering temperatures were designed as 560, 620 and 680℃, respectively. Rapid tempering specimens were heated at a heating rate of 20 ℃/s, and all samples of these three tempering temperatures were maintained 30, 40 and 50 s with the Gleeble1500-D tester, respectively. The impact test at --40 ℃ were carried out on a Charpy impact machine （CBD-300） with a maximum measurement range of 300 J and the microstructures were analyzed in detail using optical microscope （OM） and scanning electron microscope （SEM）. The experiment results show that the upper bainite, martensite and small amount of austenite were obtained in the rapidly quenched samples. In comparison to the conventional process, the matrix microstructure was changed from the larger size and bulk ferrite to the refined banding structure, and the cementites were obviously refined and precipitated inside the grains and along the grain boundaries. The cryogenic impact test implies that the maximum values of impact toughness with holding time of 30 or 50 s are achieved at tempering temperature of 620℃. Furthermore, a favorite value of impact toughness with holding time of 40 s is available.展开更多
In the engineering.to ensure the quality and safety,it is necessary to carry out reliability analysis on it.When conducting reliability analysis in engineering.a 1arge rumber of small1 failure probability problems wil...In the engineering.to ensure the quality and safety,it is necessary to carry out reliability analysis on it.When conducting reliability analysis in engineering.a 1arge rumber of small1 failure probability problems will be encountered.For such problems,the traditional Monte Carlo method needs a 1ot of samples,and the calculation efficiency is extremely 1ow,while the subset sinmulation method can efficiently estimate the relLability index of the small failure probability problem with litle samples.Therefore,this paper takes the application of the subset simulation method in the reliability analysis of the small failure probability structure as the object,constructs the reliability analysis method of the single failure mode of the system and applies the method to a mathematical example and a single-story gate.Through the rigid frame example,it can be seen that this method is beneficial to improve the calculation efficiency and accuracy.展开更多
The human factors and their interaction with other factors play an important role in the flight safety of transport aircraft.In this paper,a paradigm of risk assessment for transport aircraft interacting with piloting...The human factors and their interaction with other factors play an important role in the flight safety of transport aircraft.In this paper,a paradigm of risk assessment for transport aircraft interacting with piloting behaviors is proposed,with focus on landing which is the most accident-prone flight stage in aviation safety statistics.Model-based flight simulation serves as our data source for landing risk analysis under uncertainties.A digital pilot in the loop that reflects the human piloting behaviors is employed to facilitate simulation efficiency.Eight types of unsafe events in landing are identified from statistics.On this basis,the landing safety boundary is extracted via stochastic simulation to divide safety and hazardous flight status domains,which con-tributes to flight status management and risk warning.The simulation results indicate that appro-priate piloting behavior,which is active response and fast target acquisition with minimum overshoot and fluctuation,shows benefit to landing safety.The subset simulation technique is employed to further refine the boundary with less computational workload.Furthermore,the effect of airspeed,windspeed,and other factors on landing risk is also discussed.The proposed risk assess-ment method would help optimize operation procedure and develop targeted pilot training program.展开更多
The research addresses the prevalence of gassy soil, containing methane (CH4), within the soil particles of southeast coastal areas of China, such as the Quaternary deposit in the Hangzhou Bay area. This soil exhibits...The research addresses the prevalence of gassy soil, containing methane (CH4), within the soil particles of southeast coastal areas of China, such as the Quaternary deposit in the Hangzhou Bay area. This soil exhibits spatial variability in the distribution of gas pressure, posing a potential threat of engineering disasters, including fire outbreaks and blasting, during the construction of underground projects. Consequently, it is crucial to assess the risk state of gas pressure, involving accurate identification and reduction of associated uncertainty, through site investigation. This is indispensable prior to the commencement of underground projects. However, during the site investigation stage, the random field parameters that quantify the spatial variability distribution of gas pressure (e.g., mean value, standard deviations, and scale of fluctuation) are unknown, introducing corresponding statistical uncertainty. Therefore, the most significant consideration for planning site investigation from an engineering perspective involves determining the risk state of gas pressure while considering the statistical uncertainty of these random field parameters. This consideration heavily relies on the engineering experience gained from current site investigation practices. To address this challenge, the study introduces a probabilistic site investigation optimization method designed for planning the site investigation scheme for gassy soils, including determining the number and locations of boreholes. The method is based on the expected state-identification probability, representing the probability of identifying the risk state of gas pressure, and takes into account the statistical uncertainty of random field parameters. The proposed method aims to determine an optimal investigation scheme before conducting the site investigation, leveraging prior knowledge. This optimal scheme is identified using Subset Simulation Optimization (SSO) in the space of candidate site investigations, maximizing the value of the expected state-identification probability at the minimal value point. Finally, the paper illustrates the proposed approach through a case study.展开更多
文摘The maintenance of safety and dependability in rail and road embankments is of utmost importance in order to facilitate the smooth operation of transportation networks.This study introduces a comprehensive methodology for soil slope stability evaluation,employing Monte Carlo Simulation(MCS)and Subset Simulation(SS)with the"UPSS 3.0 Add-in"in MS-Excel.Focused on an 11.693-meter embankment with a soil slope(inclination ratio of 2H:1V),the investigation considers earthquake coefficients(kh)and pore water pressure ratios(ru)following Indian zoning requirements.The chance of slope failure showed a considerable increase as the Coefficient of Variation(COV),seismic coefficients(kh),and pore water pressure ratios(ru)experienced an escalation.The SS approach showed exceptional efficacy in calculating odds of failure that are notably low.Within computational modeling,the study optimized the worst-case scenario using ANFIS-GA,ANFIS-GWO,ANFIS-PSO,and ANFIS-BBO models.The ANFIS-PSO model exhibits exceptional accuracy(training R2=0.9011,RMSE=0.0549;testing R2=0.8968,RMSE=0.0615),emerging as the most promising.This study highlights the significance of conducting thorough risk assessments and offers practical insights into evaluating and improving the stability of soil slopes in transportation infrastructure.These findings contribute to the enhancement of safety and reliability in real-world situations.
基金Foundation item:the National Natural Science Foundation of China(No.52075101)the Natural Science Foundation of Guangdong Province(No.2017A030313265)Guangzhou Scientific Research Plan(No.201904010184)。
文摘Aimed at the problem of the low computational efficiency of the existing urethral-valve reliability analysis,an efficient reliability analysis method of the wireless energy-transmitting urethral-valve(WETUV)was proposed.The method is called FTA-AK-SS,based on the active learning Kriging(AK)model,subset simulation(SS)algorithm,and fault tree analysis(FTA).According to the principle of FTA,we established the fault tree model of the WETUV to determine its minimum cut set and bottom events.Then we defined the random variables affecting its reliability.The U learning function was used to selectively add the sample points of random variables to update the initial Kriging surrogate model.At the same time,combined with the SS algorithm,the reliability and sensitivity analyses of the WETUV were realized.The result shows that compared with the traditional Monte Carlo simulation and FTA-Kriging-SS methods,the proposed method significantly improves the calculation efficiency of the WETUV under the premise of ensuring calculation accuracy.The reliability of the WETUV is greatly affected by the rubber pad’s aging,the receiver coil’s corrosion,and the position deviation.This study can provide a new way to realize a high-efficiency reliability calculation and analysis for urethral valves.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51978589,51778544,and 51525804).
文摘The response of the train–bridge system has an obvious random behavior.A high traffic density and a long maintenance period of a track will result in a substantial increase in the number of trains running on a bridge,and there is small likelihood that the maximum responses of the train and bridge happen in the total maintenance period of the track.Firstly,the coupling model of train–bridge systems is reviewed.Then,an ensemble method is presented,which can estimate the small probabilities of a dynamic system with stochastic excitations.The main idea of the ensemble method is to use the NARX(nonlinear autoregressive with exogenous input)model to replace the physical model and apply subset simulation with splitting to obtain the extreme distribution.Finally,the efficiency of the suggested method is compared with the direct Monte Carlo simulation method,and the probability exceedance of train responses under the vertical track irregularity is discussed.The results show that when the small probability of train responses under vertical track irregularity is estimated,the ensemble method can reduce both the calculation time of a single sample and the required number of samples.
文摘Quasi-ellipsoidal gear transmission mechanism, which is the newest transmission mechanism used for robot flexible wrist at present, has simple structure, light weight,small dimension, high sensitivity and can accurately carry out the motion transmission in all-direction. It is a new type of transmission used for robot flexible wrist at present. Different from ordinary transmission mechanisms it is a spatial mesh with double DOF. Its design is complicated, and there are many approximate treatments in checking interference of flank and distribution of teeth. The purpose of this paper is to verify the reliability of the design by means of computer simulation.
文摘The design of a pixel processor of a real-time CIG (Computer Image Generation) system is summarized. The system has been brought into use. In order to adopt ASIC (Application-Specific integrated Circuit) technology in the design of the new system, the VHDL (Very high speed integrated circuit Hardware Description Language) is used and a re-design and simulation strategy is planed.
文摘This paper deals with identification of subset autoregressive time series model. A simulated annealing based on approach for deter min ing the optimal subset of regression terms included in the subset autogressive model is introduced. Numerical examples are given to show the effectiveness of the proposed algorithm.
基金Sponsored by Natural Science Foundation of Inner Mongolia Autonomous Region of China (Grant No.2009MS0811)
文摘The effect of refined precipitations and dispersed phases on the toughness of SS400 steel was investigated by rapid tempering with thermomechanical simulation tester, and the electromagnetic induction rapid tempering process was simulated. The conventional tempering and rapid tempering process were proceeded respectively, and both samples were quenched in 10~ of agitated iced brine. The tempering temperatures were designed as 560, 620 and 680℃, respectively. Rapid tempering specimens were heated at a heating rate of 20 ℃/s, and all samples of these three tempering temperatures were maintained 30, 40 and 50 s with the Gleeble1500-D tester, respectively. The impact test at --40 ℃ were carried out on a Charpy impact machine （CBD-300） with a maximum measurement range of 300 J and the microstructures were analyzed in detail using optical microscope （OM） and scanning electron microscope （SEM）. The experiment results show that the upper bainite, martensite and small amount of austenite were obtained in the rapidly quenched samples. In comparison to the conventional process, the matrix microstructure was changed from the larger size and bulk ferrite to the refined banding structure, and the cementites were obviously refined and precipitated inside the grains and along the grain boundaries. The cryogenic impact test implies that the maximum values of impact toughness with holding time of 30 or 50 s are achieved at tempering temperature of 620℃. Furthermore, a favorite value of impact toughness with holding time of 40 s is available.
基金funded by the Sichuan Science and Technology Innovation Seedling Project Funding Project (Grant No.2021112).
文摘In the engineering.to ensure the quality and safety,it is necessary to carry out reliability analysis on it.When conducting reliability analysis in engineering.a 1arge rumber of small1 failure probability problems will be encountered.For such problems,the traditional Monte Carlo method needs a 1ot of samples,and the calculation efficiency is extremely 1ow,while the subset sinmulation method can efficiently estimate the relLability index of the small failure probability problem with litle samples.Therefore,this paper takes the application of the subset simulation method in the reliability analysis of the small failure probability structure as the object,constructs the reliability analysis method of the single failure mode of the system and applies the method to a mathematical example and a single-story gate.Through the rigid frame example,it can be seen that this method is beneficial to improve the calculation efficiency and accuracy.
基金supported by the Airworthiness Technology Research Center of Beihang University,China.
文摘The human factors and their interaction with other factors play an important role in the flight safety of transport aircraft.In this paper,a paradigm of risk assessment for transport aircraft interacting with piloting behaviors is proposed,with focus on landing which is the most accident-prone flight stage in aviation safety statistics.Model-based flight simulation serves as our data source for landing risk analysis under uncertainties.A digital pilot in the loop that reflects the human piloting behaviors is employed to facilitate simulation efficiency.Eight types of unsafe events in landing are identified from statistics.On this basis,the landing safety boundary is extracted via stochastic simulation to divide safety and hazardous flight status domains,which con-tributes to flight status management and risk warning.The simulation results indicate that appro-priate piloting behavior,which is active response and fast target acquisition with minimum overshoot and fluctuation,shows benefit to landing safety.The subset simulation technique is employed to further refine the boundary with less computational workload.Furthermore,the effect of airspeed,windspeed,and other factors on landing risk is also discussed.The proposed risk assess-ment method would help optimize operation procedure and develop targeted pilot training program.
文摘The research addresses the prevalence of gassy soil, containing methane (CH4), within the soil particles of southeast coastal areas of China, such as the Quaternary deposit in the Hangzhou Bay area. This soil exhibits spatial variability in the distribution of gas pressure, posing a potential threat of engineering disasters, including fire outbreaks and blasting, during the construction of underground projects. Consequently, it is crucial to assess the risk state of gas pressure, involving accurate identification and reduction of associated uncertainty, through site investigation. This is indispensable prior to the commencement of underground projects. However, during the site investigation stage, the random field parameters that quantify the spatial variability distribution of gas pressure (e.g., mean value, standard deviations, and scale of fluctuation) are unknown, introducing corresponding statistical uncertainty. Therefore, the most significant consideration for planning site investigation from an engineering perspective involves determining the risk state of gas pressure while considering the statistical uncertainty of these random field parameters. This consideration heavily relies on the engineering experience gained from current site investigation practices. To address this challenge, the study introduces a probabilistic site investigation optimization method designed for planning the site investigation scheme for gassy soils, including determining the number and locations of boreholes. The method is based on the expected state-identification probability, representing the probability of identifying the risk state of gas pressure, and takes into account the statistical uncertainty of random field parameters. The proposed method aims to determine an optimal investigation scheme before conducting the site investigation, leveraging prior knowledge. This optimal scheme is identified using Subset Simulation Optimization (SSO) in the space of candidate site investigations, maximizing the value of the expected state-identification probability at the minimal value point. Finally, the paper illustrates the proposed approach through a case study.
