The first in China pilot tests of fixed-bed methanol-topropylene unit were successfully implemented at the Yangzi Petrochemical Company(YPC).It is told that this technology has opened up a new process for production o...The first in China pilot tests of fixed-bed methanol-topropylene unit were successfully implemented at the Yangzi Petrochemical Company(YPC).It is told that this technology has opened up a new process for production of propylene through coal gasification,and China has possessed both the fluidized-bed methanolto-propylene process(F-MTP)and the展开更多
During the experiments with low temperature plasma treating the ramie degumming microbe,the authors found some kinds of microbe which can degum ramie in 5-6L fluid very quickly.In comparison with some standards of mic...During the experiments with low temperature plasma treating the ramie degumming microbe,the authors found some kinds of microbe which can degum ramie in 5-6L fluid very quickly.In comparison with some standards of microbiological experiments,5L or 6L-scale can be called the small-scale.Therefore,the authors believe that the experiments of the microbial quick-degumming ramie can be enlarged from the laboratory-scale test to be applied in the future.展开更多
Long-span bridges are special structures that require advanced analysis techniques to examine their performance. This paper presents a procedure developed to model the Confederation Bridge using 3-D beam elements. The...Long-span bridges are special structures that require advanced analysis techniques to examine their performance. This paper presents a procedure developed to model the Confederation Bridge using 3-D beam elements. The model was validated using the data collected before the opening of the bridge to the public. The bridge was instrumented to conduct fullscale static and dynamic tests. The static tests were to measure the deflection of the bridge pier while the dynamic tests to measure the free vibrations of the pier due to a sudden release of the static load. Confederation Bridge is one of the longest reinforced concrete bridges in the world. It connects the province of Prince Edward Island and the province of New Brunswick in Canada. Due to its strategic location and vital role as a transportation link between these two provinces, it was designed using higher safety factors than those for typical highway bridges. After validating the present numerical model, a procedure was developed to evaluate the performance of similar bridges subjected to traffic and seismic loads. It is of interest to note that the foundation stiffness and the modulus of elasticity of the concrete have significant effects on the structural responses of the Confederation Bridge.展开更多
Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and ...Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.展开更多
This paper puts forward a high-speed train bogie active stability method,based on frame lateral vibration control,for improving the stability and critical speed of railway vehicles at high speeds.Two inertial actuator...This paper puts forward a high-speed train bogie active stability method,based on frame lateral vibration control,for improving the stability and critical speed of railway vehicles at high speeds.Two inertial actuators apply active control forces to the front and rear end beams of the bogie frame.A scale model of bogie lateral dynamics is established,as well as the state space equation of the control system.Also,the multi-objective optimization is used to construct state feedback parameters,which take hunting stability and control effort into account.Furthermore,the effects of time-delay in the control system and suspension parameters on bogie hunting stability are studied.The dynamic behaviors and the stability mechanism of the bogie control system are analyzed.Finally,a 1:5 scale test rig is used to conduct a bogie active stability experiment.The results reveal that active control of frame lateral vibration can effectively improve the bogie system's hunting stability margin at high speeds,but time-delay in the control system cannot be ignored.展开更多
In wheel–rail adhesion studies,most of the test rigs used are simplified designs such as a single wheel or wheelset,but the results may not be accurate.Alternatively,representing the complex system by using a full ve...In wheel–rail adhesion studies,most of the test rigs used are simplified designs such as a single wheel or wheelset,but the results may not be accurate.Alternatively,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in design.To trade off accuracy over complexity,a bogie model can be the optimum selection.Furthermore,only a real-time model can replicate its physical counterpart in the time domain.Developing such a model requires broad expertise and appropriate software and hardware.A few published works are available which deal with real-time modeling.However,the influence of the control system has not been included in those works.To address these issues,a real-time scaled bogie test rig including the control system is essential.Therefore,a 1:4 scaled bogie roller rig is developed to study the adhesion between wheel and roller contact.To compare the performances obtained from the scaled bogie test rig and to expand the test applications,a numerical simulation model of that scaled bogie test rig is developed using Gensys multibody software.This model is the complete model of the test rig which delivers more precise results.To exactly represent the physical counterpart system in the time domain,a real-time scaled bogie test rig(RT-SBTR)is developed after four consecutive stages.Then,to simulate the RT-SBTR to solve the internal state equations and functions representing the physical counterpart system in rigs used are simplified designs such as a single wheel or wheelset,but the results may not be accurate.Alternatively,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in design.To trade off accuracy over complexity,a bogie model can be the optimum selection.Furthermore,only a real-time model can replicate its physical counterpart in the time domain.Developing such a model requires broad expertise and appropriate software and hardware.A few published works are available which deal with real-time modeling.However,the influence of the control system has not been included in those works.To address these issues,a real-time scaled bogie test rig including the control system is essential.Therefore,a 1:4 scaled bogie roller rig is developed to study the adhesion between wheel and roller contact.To compare the performances obtained from the scaled bogie test rig and to expand the test applications,a numerical simulation model of that scaled bogie test rig is developed using Gensys multibody software.This model is the complete model of the test rig which delivers more precise results.To exactly represent the physical counterpart system in the time domain,a real-time scaled bogie test rig(RT-SBTR)is developed after four consecutive stages.Then,to simulate the RT-SBTR to solve the internal state equations and functions representing the physical counterpart system in equal or less than actual time,the real-time simulation environment is prepared in two stages.To such end,the computational time improved from 4 times slower than real time to 2 times faster than real time.Finally,the real-time scaled bogie model is also incorporated with the braking control system which slightly reduces the computational performances without affecting real-time capability.展开更多
BACKGROUND Childhood asthma is a common respiratory ailment that significantly affects preschool children.Effective asthma management in this population is particularly challenging due to limited communication skills ...BACKGROUND Childhood asthma is a common respiratory ailment that significantly affects preschool children.Effective asthma management in this population is particularly challenging due to limited communication skills in children and the necessity for consistent involvement of a caregiver.With the rise of digital healthcare and the need for innovative interventions,Internet-based models can potentially offer relatively more efficient and patient-tailored care,especially in children.AIM To explore the impact of an intelligent Internet care model based on the child respiratory and asthma control test(TRACK)on asthma management in preschool children.METHODS The study group comprised preschoolers,aged 5 years or younger,that visited the hospital's pediatric outpatient and emergency departments between January 2021 and January 2022.Total of 200 children were evenly and randomly divided into the observation and control groups.The control group received standard treatment in accordance with the 2016 Guidelines for Pediatric Bronchial Asthma and the Global Initiative on Asthma.In addition to above treatment,the observation group was introduced to an intelligent internet nursing model,emphasizing the TRACK scale.Key measures monitored over a six-month period included the frequency of asthma attack,emergency visits,pulmonary function parameters(FEV1,FEV1/FVC,and PEF),monthly TRACK scores,and the SF-12 quality of life assessment.Post-intervention asthma control rates were assessed at six-month follow-up.RESULTS The observation group had fewer asthma attacks and emergency room visits than the control group(P<0.05).After six months of treatment,the children in both groups had higher FEV1,FEV1/FVC,and PEF(P<0.05).Statistically significant differences were observed between the two groups(P<0.05).For six months,children in the observation group had a higher monthly TRACK score than those in the control group(P<0.05).The PCS and MCSSF-12 quality of life scores were relatively higher than those before the nursing period(P<0.05).Furthermore,the groups showed statistically significant differences(P<0.05).The asthma control rate was higher in the observation group than in the control group(P<0.05).CONCLUSION TRACK based Intelligent Internet nursing model may reduce asthma attacks and emergency visits in asthmatic children,improve lung function,quality of life,and the TRACK score and asthma control rate.The effect of nursing was significant,allowing for development of an asthma management model.展开更多
Crashworthy seat structure with considerable energy absorption capacity is a key component for aircraft to improve its crashworthiness and occupant survivability in emergencies.According to Federal Aviation Administra...Crashworthy seat structure with considerable energy absorption capacity is a key component for aircraft to improve its crashworthiness and occupant survivability in emergencies.According to Federal Aviation Administration(FAA) regulations,seat performance must be certified by dynamic crash test which is quite expensive and time-consuming.For this reason,numerical simulation is a more efficient and economical approach to provide the possibility to assess seat performances and predict occupant responses.A numerical simulation of the crashworthy seat structure was presented and the results were also compared with the full-scale crash test data.In the numerical simulation,a full-scale three-dimensional finite element model of the seat/occupant structure was developed using a nonlinear and explicit dynamic finite element code LS-DYNA3D.Emphasis of the numerical simulation was on predicting the dynamic response of seat/occupant system,including the occupant motion which may lead to injuries,the occupant acceleration-time histories,and the energy absorbing behavior of the energy absorbers.The agreement between the simulation and the physical test suggestes that the developed numerical simulation can be a feasible substitute for the dynamic crash test.展开更多
A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element （FE） numerical substructures. The analysis of the FE numerical substructure is split into response anal...A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element （FE） numerical substructures. The analysis of the FE numerical substructure is split into response analysis and signal generation tasks, and executed in two different target computers in real-time. One target computer implements the response analysis task, wherein a large time-step is used to solve the FE substructure, and another target computer implements the signal generation task, wherein an interpolation program is used to generate control signals in a small time-step to meet the input demand of the controller. By using this strategy, the scale of the FE numerical substructure simulation may be increased significantly. The proposed scheme is initially verified by two FE numerical substructure models with 98 and 1240 degrees of freedom （DOFs）. Thereafter, RTDHTs of a single frame-foundation structure are implemented where the foundation, considered as the numerical substructure, is simulated by the FE model with 1240 DOFs. Good agreements between the results of the RTDHT and those from the FE analysis in ABAQUS are obtained.展开更多
The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the t...The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust holes.In order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were conducted.By changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were studied.On this basis,the optimal smoke control strategy was proposed for different fire scenarios.The research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels.展开更多
Full scale aircraft static test is a very important process of aircraft design, it is costly and time consuming. The testing accuracy and validity mainly depend on the rationality of the test scheme design. When the a...Full scale aircraft static test is a very important process of aircraft design, it is costly and time consuming. The testing accuracy and validity mainly depend on the rationality of the test scheme design. When the aircraft is being tested, the specimen＇s safety mainly depends on monitoring and understanding the testing data by way of evaluating the coherence with the digital simulation data synchyononsly. The test digital simulation can aid realizing above requirements and improving the test efficiency significantly during test scheme design stage or testing stage respectively. The key technologies and the solving methods of test digital simulation are presented and the application example is given.展开更多
t According to a general representation of physical scale factor of RCS for variance in the size of simply shaped scatterers, a novel RCS model-testing method is described. The computed results of the prototype scatte...t According to a general representation of physical scale factor of RCS for variance in the size of simply shaped scatterers, a novel RCS model-testing method is described. The computed results of the prototype scatterers by this method from the model-testing agree well with their measured values both for two kinds of simply shaped scatterers, cylinders and ladder-shaped plates.展开更多
As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and m...As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and more important. Traditional dynamic simulation systems and digital-analog hybrid simulation systems are difficult to compromise on the economy, flexibility and accuracy. A multi-time scale test system of doubly fed induction generator based on FPGA+ CPU heterogeneous calculation is proposed in this paper. The proposed test system is based on the ADPSS simulation platform. The power circuit part of the test system is setup up using the EMT(electromagnetic transient simulation) simulation, and the control part uses the actual physical devices. In order to realize the close-loop testing for the physical devices, the power circuit must be simulated in real-time. This paper proposes a multi-time scale simulation algorithm, in which the decoupling component divides the power circuit into a large time scale system and a small time scale system in order to reduce computing effort. This paper also proposes the FPGA+CPU heterogeneous computing architecture for implementing this multitime scale simulation. In FPGA, there is a complete small time-scale EMT engine, which support the flexibly circuit modeling with any topology. Finally, the test system is connected to an DFIG controller based on Labview to verify the feasibility of the test system.展开更多
The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment proce...The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment process for the high-strength Chinese traditional medicine wastewater. This article was focused on the feasibility of the wastewater treatment and reuse at shorter hydraulic retention time （HRT） of 5.0, 3.2 and 2.13 h. MLSS growth, membrane flux, vacuum values and chemical cleaning periods were also investigated. The experimental results of treating two-phase anaerobic treatment effluent demonstrated that the CODfilt was less than 100 mg/L when the influent COD was between 500-10000 mg/L at HRT of 5.0 h, which could satisfy the normal discharged standard in China. The experimental results to treat cross flow aerobic reactor effluent demonstrated that the average value of CODfilt was 17.28 mg/L when the average value of influent COD was 192.84 mg/L at HRT of 2.13 h during 106 d, which could completely meet the normal standard for water reuse. The maximum MLSS and MLVSS reached 24000 and 14500 mg/L at HRT of 3.2 h respectively. Membrane flux had maximal resume degrees of 94.7% at vacuum value of 0.02 MPa after cleaning. Chemical cleaning periods of membrane module were 150 d. A simulation model of operational parameters was also established based on the theory of back propagation neural network and linear regression of traditional mathematical model. The simulation model showed that the optimum operational parameters were suggested as follows： HRT was 5.0 h, SRT was 100 d, the range of COD loading rate was between 10.664-20.451 kg/（m3.d）, the range of MLSS was between 7543-13694 mg/L.展开更多
文摘The first in China pilot tests of fixed-bed methanol-topropylene unit were successfully implemented at the Yangzi Petrochemical Company(YPC).It is told that this technology has opened up a new process for production of propylene through coal gasification,and China has possessed both the fluidized-bed methanolto-propylene process(F-MTP)and the
基金China Hubei Provincial Science and Technology Department(2005ABB035)the foundation of excellent youth in Hubei ProvinceChina Hubei Provincial Education Department(Q200717007).
文摘During the experiments with low temperature plasma treating the ramie degumming microbe,the authors found some kinds of microbe which can degum ramie in 5-6L fluid very quickly.In comparison with some standards of microbiological experiments,5L or 6L-scale can be called the small-scale.Therefore,the authors believe that the experiments of the microbial quick-degumming ramie can be enlarged from the laboratory-scale test to be applied in the future.
文摘Long-span bridges are special structures that require advanced analysis techniques to examine their performance. This paper presents a procedure developed to model the Confederation Bridge using 3-D beam elements. The model was validated using the data collected before the opening of the bridge to the public. The bridge was instrumented to conduct fullscale static and dynamic tests. The static tests were to measure the deflection of the bridge pier while the dynamic tests to measure the free vibrations of the pier due to a sudden release of the static load. Confederation Bridge is one of the longest reinforced concrete bridges in the world. It connects the province of Prince Edward Island and the province of New Brunswick in Canada. Due to its strategic location and vital role as a transportation link between these two provinces, it was designed using higher safety factors than those for typical highway bridges. After validating the present numerical model, a procedure was developed to evaluate the performance of similar bridges subjected to traffic and seismic loads. It is of interest to note that the foundation stiffness and the modulus of elasticity of the concrete have significant effects on the structural responses of the Confederation Bridge.
基金financial support for much of the early development of the AE analysis methods was provided by the U.S. Department of Energy (DOE) (Grant No. DE-FE0002760)
文摘Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.
基金supported by the National Railway Group Science and Technology Program(Nos.N2020J026 and N2021J028)the Independent Research and Development Projects of Traction Power State Key Laboratory(No.2022TPL-T02),China。
文摘This paper puts forward a high-speed train bogie active stability method,based on frame lateral vibration control,for improving the stability and critical speed of railway vehicles at high speeds.Two inertial actuators apply active control forces to the front and rear end beams of the bogie frame.A scale model of bogie lateral dynamics is established,as well as the state space equation of the control system.Also,the multi-objective optimization is used to construct state feedback parameters,which take hunting stability and control effort into account.Furthermore,the effects of time-delay in the control system and suspension parameters on bogie hunting stability are studied.The dynamic behaviors and the stability mechanism of the bogie control system are analyzed.Finally,a 1:5 scale test rig is used to conduct a bogie active stability experiment.The results reveal that active control of frame lateral vibration can effectively improve the bogie system's hunting stability margin at high speeds,but time-delay in the control system cannot be ignored.
基金The authors greatly appreciate the financial support from the Rail Manufacturing Cooperative Research Centre(funded jointly by participating rail organizations and the Australian Federal Government’s Business Cooperative Research Centres Program)through Project R1.7.1-“Estimation of adhesion conditions between wheels and rails for the development of advanced braking control systems.”Tim McSweeney,Adjunct Research Fellow,Centre for Railway Engineering is thankfully acknowledged for his assistance with proofreading.
文摘In wheel–rail adhesion studies,most of the test rigs used are simplified designs such as a single wheel or wheelset,but the results may not be accurate.Alternatively,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in design.To trade off accuracy over complexity,a bogie model can be the optimum selection.Furthermore,only a real-time model can replicate its physical counterpart in the time domain.Developing such a model requires broad expertise and appropriate software and hardware.A few published works are available which deal with real-time modeling.However,the influence of the control system has not been included in those works.To address these issues,a real-time scaled bogie test rig including the control system is essential.Therefore,a 1:4 scaled bogie roller rig is developed to study the adhesion between wheel and roller contact.To compare the performances obtained from the scaled bogie test rig and to expand the test applications,a numerical simulation model of that scaled bogie test rig is developed using Gensys multibody software.This model is the complete model of the test rig which delivers more precise results.To exactly represent the physical counterpart system in the time domain,a real-time scaled bogie test rig(RT-SBTR)is developed after four consecutive stages.Then,to simulate the RT-SBTR to solve the internal state equations and functions representing the physical counterpart system in rigs used are simplified designs such as a single wheel or wheelset,but the results may not be accurate.Alternatively,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in design.To trade off accuracy over complexity,a bogie model can be the optimum selection.Furthermore,only a real-time model can replicate its physical counterpart in the time domain.Developing such a model requires broad expertise and appropriate software and hardware.A few published works are available which deal with real-time modeling.However,the influence of the control system has not been included in those works.To address these issues,a real-time scaled bogie test rig including the control system is essential.Therefore,a 1:4 scaled bogie roller rig is developed to study the adhesion between wheel and roller contact.To compare the performances obtained from the scaled bogie test rig and to expand the test applications,a numerical simulation model of that scaled bogie test rig is developed using Gensys multibody software.This model is the complete model of the test rig which delivers more precise results.To exactly represent the physical counterpart system in the time domain,a real-time scaled bogie test rig(RT-SBTR)is developed after four consecutive stages.Then,to simulate the RT-SBTR to solve the internal state equations and functions representing the physical counterpart system in equal or less than actual time,the real-time simulation environment is prepared in two stages.To such end,the computational time improved from 4 times slower than real time to 2 times faster than real time.Finally,the real-time scaled bogie model is also incorporated with the braking control system which slightly reduces the computational performances without affecting real-time capability.
基金Supported by Science and Technology Research Project of Songjiang District,No.2020SJ340.
文摘BACKGROUND Childhood asthma is a common respiratory ailment that significantly affects preschool children.Effective asthma management in this population is particularly challenging due to limited communication skills in children and the necessity for consistent involvement of a caregiver.With the rise of digital healthcare and the need for innovative interventions,Internet-based models can potentially offer relatively more efficient and patient-tailored care,especially in children.AIM To explore the impact of an intelligent Internet care model based on the child respiratory and asthma control test(TRACK)on asthma management in preschool children.METHODS The study group comprised preschoolers,aged 5 years or younger,that visited the hospital's pediatric outpatient and emergency departments between January 2021 and January 2022.Total of 200 children were evenly and randomly divided into the observation and control groups.The control group received standard treatment in accordance with the 2016 Guidelines for Pediatric Bronchial Asthma and the Global Initiative on Asthma.In addition to above treatment,the observation group was introduced to an intelligent internet nursing model,emphasizing the TRACK scale.Key measures monitored over a six-month period included the frequency of asthma attack,emergency visits,pulmonary function parameters(FEV1,FEV1/FVC,and PEF),monthly TRACK scores,and the SF-12 quality of life assessment.Post-intervention asthma control rates were assessed at six-month follow-up.RESULTS The observation group had fewer asthma attacks and emergency room visits than the control group(P<0.05).After six months of treatment,the children in both groups had higher FEV1,FEV1/FVC,and PEF(P<0.05).Statistically significant differences were observed between the two groups(P<0.05).For six months,children in the observation group had a higher monthly TRACK score than those in the control group(P<0.05).The PCS and MCSSF-12 quality of life scores were relatively higher than those before the nursing period(P<0.05).Furthermore,the groups showed statistically significant differences(P<0.05).The asthma control rate was higher in the observation group than in the control group(P<0.05).CONCLUSION TRACK based Intelligent Internet nursing model may reduce asthma attacks and emergency visits in asthmatic children,improve lung function,quality of life,and the TRACK score and asthma control rate.The effect of nursing was significant,allowing for development of an asthma management model.
基金The National Natural Science Foundation of China(11032001)the Fundamental Research Funds for the Central Universities
文摘Crashworthy seat structure with considerable energy absorption capacity is a key component for aircraft to improve its crashworthiness and occupant survivability in emergencies.According to Federal Aviation Administration(FAA) regulations,seat performance must be certified by dynamic crash test which is quite expensive and time-consuming.For this reason,numerical simulation is a more efficient and economical approach to provide the possibility to assess seat performances and predict occupant responses.A numerical simulation of the crashworthy seat structure was presented and the results were also compared with the full-scale crash test data.In the numerical simulation,a full-scale three-dimensional finite element model of the seat/occupant structure was developed using a nonlinear and explicit dynamic finite element code LS-DYNA3D.Emphasis of the numerical simulation was on predicting the dynamic response of seat/occupant system,including the occupant motion which may lead to injuries,the occupant acceleration-time histories,and the energy absorbing behavior of the energy absorbers.The agreement between the simulation and the physical test suggestes that the developed numerical simulation can be a feasible substitute for the dynamic crash test.
基金National Natural Science Foundation under Grant Nos.51179093,91215301 and 41274106the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20130002110032Tsinghua University Initiative Scientific Research Program under Grant No.20131089285
文摘A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element （FE） numerical substructures. The analysis of the FE numerical substructure is split into response analysis and signal generation tasks, and executed in two different target computers in real-time. One target computer implements the response analysis task, wherein a large time-step is used to solve the FE substructure, and another target computer implements the signal generation task, wherein an interpolation program is used to generate control signals in a small time-step to meet the input demand of the controller. By using this strategy, the scale of the FE numerical substructure simulation may be increased significantly. The proposed scheme is initially verified by two FE numerical substructure models with 98 and 1240 degrees of freedom （DOFs）. Thereafter, RTDHTs of a single frame-foundation structure are implemented where the foundation, considered as the numerical substructure, is simulated by the FE model with 1240 DOFs. Good agreements between the results of the RTDHT and those from the FE analysis in ABAQUS are obtained.
基金National Natural Science Foundation of China,Grant/Award Numbers:72091512,52104198,52374210。
文摘The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust holes.In order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were conducted.By changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were studied.On this basis,the optimal smoke control strategy was proposed for different fire scenarios.The research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels.
文摘Full scale aircraft static test is a very important process of aircraft design, it is costly and time consuming. The testing accuracy and validity mainly depend on the rationality of the test scheme design. When the aircraft is being tested, the specimen＇s safety mainly depends on monitoring and understanding the testing data by way of evaluating the coherence with the digital simulation data synchyononsly. The test digital simulation can aid realizing above requirements and improving the test efficiency significantly during test scheme design stage or testing stage respectively. The key technologies and the solving methods of test digital simulation are presented and the application example is given.
文摘t According to a general representation of physical scale factor of RCS for variance in the size of simply shaped scatterers, a novel RCS model-testing method is described. The computed results of the prototype scatterers by this method from the model-testing agree well with their measured values both for two kinds of simply shaped scatterers, cylinders and ladder-shaped plates.
基金supported by the State Grid Science and Technology Project (Title: Technology Research On Large Scale EMT Real-time simulation customized platform, FX71-17-001)
文摘As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and more important. Traditional dynamic simulation systems and digital-analog hybrid simulation systems are difficult to compromise on the economy, flexibility and accuracy. A multi-time scale test system of doubly fed induction generator based on FPGA+ CPU heterogeneous calculation is proposed in this paper. The proposed test system is based on the ADPSS simulation platform. The power circuit part of the test system is setup up using the EMT(electromagnetic transient simulation) simulation, and the control part uses the actual physical devices. In order to realize the close-loop testing for the physical devices, the power circuit must be simulated in real-time. This paper proposes a multi-time scale simulation algorithm, in which the decoupling component divides the power circuit into a large time scale system and a small time scale system in order to reduce computing effort. This paper also proposes the FPGA+CPU heterogeneous computing architecture for implementing this multitime scale simulation. In FPGA, there is a complete small time-scale EMT engine, which support the flexibly circuit modeling with any topology. Finally, the test system is connected to an DFIG controller based on Labview to verify the feasibility of the test system.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No. 2002AA601310).
文摘The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment process for the high-strength Chinese traditional medicine wastewater. This article was focused on the feasibility of the wastewater treatment and reuse at shorter hydraulic retention time （HRT） of 5.0, 3.2 and 2.13 h. MLSS growth, membrane flux, vacuum values and chemical cleaning periods were also investigated. The experimental results of treating two-phase anaerobic treatment effluent demonstrated that the CODfilt was less than 100 mg/L when the influent COD was between 500-10000 mg/L at HRT of 5.0 h, which could satisfy the normal discharged standard in China. The experimental results to treat cross flow aerobic reactor effluent demonstrated that the average value of CODfilt was 17.28 mg/L when the average value of influent COD was 192.84 mg/L at HRT of 2.13 h during 106 d, which could completely meet the normal standard for water reuse. The maximum MLSS and MLVSS reached 24000 and 14500 mg/L at HRT of 3.2 h respectively. Membrane flux had maximal resume degrees of 94.7% at vacuum value of 0.02 MPa after cleaning. Chemical cleaning periods of membrane module were 150 d. A simulation model of operational parameters was also established based on the theory of back propagation neural network and linear regression of traditional mathematical model. The simulation model showed that the optimum operational parameters were suggested as follows： HRT was 5.0 h, SRT was 100 d, the range of COD loading rate was between 10.664-20.451 kg/（m3.d）, the range of MLSS was between 7543-13694 mg/L.
