The microwave wireless power transmission technologies for space solar power station are a crucial field in the international space sector,where various countries are competing in its development.This paper surveys th...The microwave wireless power transmission technologies for space solar power station are a crucial field in the international space sector,where various countries are competing in its development.This paper surveys the research experiments and development efforts related to space solar power stations and microwave wireless power transmission technologies worldwide.The objective is to assess the progress and current state of this technological foundation,determine the necessary focus for developing high-power microwave wireless power transmission technology,and provide clarity on the direction of future technology development in these areas.Finally,a distributed space solar power station plan that is immediately feasible is proposed.展开更多
Metro passenger flow control problem is studied under given total inbound demand in this work,which considers passenger demand control and train capacity supply.Relevant connotations are analyzed and a mathematical mo...Metro passenger flow control problem is studied under given total inbound demand in this work,which considers passenger demand control and train capacity supply.Relevant connotations are analyzed and a mathematical model is developed.The decision variables are boarding limiting and stop-skipping strategies and the objective is the maximal passenger profit.And a passenger original station choice model based on utility theory is built to modify the inbound passenger distribution among stations.Algorithm of metro passenger flow control scheme is designed,where two key technologies of stopping-station choice and headway adjustment are given and boarding limiting and train stopping-station scheme are optimized.Finally,a real case of Beijing metro is taken for example to verify validity.The results show that in the three scenarios with different ratios of normal trains to stop-skipping trains,the total limited passenger volume is the smallest and the systematic profit is the largest in scenario 3.展开更多
Results of in-situ vibration measurement carried out at Tianjin West Elevated Railway Station which has the trains running on the station structure were reported. The main excitation source is the train passing throug...Results of in-situ vibration measurement carried out at Tianjin West Elevated Railway Station which has the trains running on the station structure were reported. The main excitation source is the train passing through the station. Vibration measurements were recorded in the vertical direction of the supporting track beam, the platform and the steel truss beam of the waiting hall, as well as in the vertical, longitudinal and transverse directions of the roof arch base of the station. Acceleration time responses were obtained. The maximum value, vibration level and one-third octave band RMS spectra of the measured accelerations were studied. The propagation of vibration in different structural floors was discussed. The influence of train speed, distance to the vibration source and the type of train on the structural vibration were analyzed. Results show that the vibration level increases with the train speed, while it attenuates with the distance to the track. Furthermore, the vibration responses of different structural floors were compared, and it is noted that the vertical vibration of the bottom slab of the platform is most severe and the transverse vibration of the roof arch base is the smallest. The results provide reference on the vibration characteristics and vibration energy distribution of this type of "Train on building frame" system used as an elevated railway station.展开更多
The core module of China’s Space Station(CSS)is scheduled to be launched around the end of 2020,and the experimental module I and II will be launched in the next two years.After on-orbit constructions,CSS will be tra...The core module of China’s Space Station(CSS)is scheduled to be launched around the end of 2020,and the experimental module I and II will be launched in the next two years.After on-orbit constructions,CSS will be transferred into an operation period over 10 years(2022–2032 and beyond)to continuously implement space science missions.At present,based on the project selection and research work in the ground development period of CSS,China is systematically making a utilization mission planning for the operation period,which focuses on the fields of aerospace medicine and human research,space life science and biotechnology,microgravity fluid physics,combustion science,materials science,fundamental physics,space astronomy and astrophysics,Earth science,space physics and space environment,space application technology,etc.In combination with the latest development trend of space science and technology,China will continue to update planning for science research and technology development,carry out project cultivation,payload R&D,and upgrade onboard and ground experiment supporting systems to achieve greater comprehensive benefits in science,technology,economy,and society。展开更多
China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar...China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar research station program,which aims to build a shared platform on the Moon jointly with many other countries for long-term and continuous lunar exploration,lunar-based observations and experiments,as well as in-situ resource utilization.In addition,China has also proposed an interstellar express mission to unveil the mysteries of the outer heliosphere,nearby interstellar space,and their interactions.This paper gives a brief introduction to the International Lunar Research Station program and the Interstellar Express mission.展开更多
The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytica...The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytical method for avoiding energy hole was proposed. It is proved that if the densities of sensor nodes working at the same time are alternate between dormancy and work with non-uniform node distribution. The efficiency of network can increase by several times and the residual energy of network is nearly zero when the network lifetime ends.展开更多
China scheduled to complete the assembly of the T-shaped Tiangong Space Station in 2022,and will enter a new stage of utilization.There are more than 20 experiment racks inside the modules,and more than 50 external on...China scheduled to complete the assembly of the T-shaped Tiangong Space Station in 2022,and will enter a new stage of utilization.There are more than 20 experiment racks inside the modules,and more than 50 external onboard payloads mounting spaces,which will support large-scale science and technology experiments during the operation.The development of internal experiment racks and external research accommodations approved during the construction has been completed,of which 4 racks in Tianhe core module,including High Microgravity Level research Rack(HMLR)and Container-less Materials Processing Rack(CMPR),have finished on-orbit tests;while other racks in Wentian and Mengtian experiment modules are under comprehensive ground tests.The Chinese Space Survey Telescope(CSST)has advanced much in the last two years with 24 pre-launch research projects funded and 4 joint science center built in preparation for CSST’s future scientific observations and operations.The systematic research planning for China’s Space Station(CSS)during 2022-2032 is updated with the researches classified into four important areas:space life sciences and human research,microgravity physical sciences,space astronomy and Earth science,and new space technologies and applications.According to the planning,more than 1000 experiments are expected to perform in CSS during the operating period.Overall,the CSS utilization missions are proceeding as planned,which will contribute to the major scientific or application output and have a positive impact on the quality of life on Earth.展开更多
The major objective of this work was to calculate evacuation capacity and solve the optimal routing problem in a given station topology from a network optimization perspective where station facilities were modelled as...The major objective of this work was to calculate evacuation capacity and solve the optimal routing problem in a given station topology from a network optimization perspective where station facilities were modelled as open finite queueing networks with a multi-objective set of performance measures. The optimal routing problem was determined so that the number of evacuation passengers was maximized while the service level was higher than a certain criterion. An analytical technique for modelling open finite queueing networks, called the iteration generalized expansion method(IGEM), was utilized to calculate the desired outputs. A differential evolution algorithm was presented for determining the optimal routes. As demonstrated, the design methodology which combines the optimization and analytical queueing network models provides a very effective procedure for simultaneously determining the service level and the maximum number of evacuation passengers in the best evacuation routes.展开更多
Organic Rankine cycle(ORC) power plant operating with supercritical parameters supplied by low temperature slag-washing water(SWW) of blast furnace was investigated.A schematic of such installation was presented with ...Organic Rankine cycle(ORC) power plant operating with supercritical parameters supplied by low temperature slag-washing water(SWW) of blast furnace was investigated.A schematic of such installation was presented with a description of its operation and the algorithm of calculations of a supercritical power plant.Two typical organic fluids with sufficiently low critical parameters were selected as candidate working fluids in the plant to study the efficiency of the system with different organic fluids.An analysis of the influence on the effectiveness of operation of a plant was carried out.With the same temperature of slag-washing water,the specific work in turbine of fluid R143a is 45% higher than that obtained for the fluid R125,however,the specific work in pump of fluid R143a is approximate equal into that one of the fluid R125.展开更多
This paper studies the problem of the space station short-term mission planning, which aims to allocate the executing time of missions effectively, schedule the corresponding resources reasonably and arrange the time ...This paper studies the problem of the space station short-term mission planning, which aims to allocate the executing time of missions effectively, schedule the corresponding resources reasonably and arrange the time of the astronauts properly. A domain model is developed by using the ontology theory to describe the concepts, constraints and relations of the planning domain formally, abstractly and normatively. A method based on time iteration is adopted to solve the short-term planning problem. Meanwhile, the resolving strategies are proposed to resolve different kinds of conflicts induced by the constraints of power, heat, resource, astronaut and relationship. The proposed approach is evaluated in a test case with fifteen missions, thirteen resources and three astronauts. The results show that the developed domain ontology model is reasonable, and the time iteration method using the proposed resolving strategies can successfully obtain the plan satisfying all considered constraints.展开更多
Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as spac...Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as space life science and biotechnology,space materials science,microgravity fundamental physics,fluid physics,combustion science,space new technologies,and applications.In this review,we introduce the progress of CSS development and provide an overview of the research conducted in Chinese Space Station and the recent scientific findings in several typical research fields.Such compelling findings mainly concern the rapid solidification of ultra-high temperature alloy melts,dynamics of fluid transport in space,gravity scaling law of boiling heat transfer,vibration fluidization phenomenon of particulate matter,cold atom interferometer technology under high microgravity and related equivalence principle testing,the full life cycle of rice under microgravity and so forth.Furthermore,the planned scientific research and corresponding prospects of Chinese space station in the next few years are presented.展开更多
The study was motivated by the fact that explosion inside the subway structure may not only cause direct life loss,but also damage the subway structure and lead to further loss of lives and properties.The propagation ...The study was motivated by the fact that explosion inside the subway structure may not only cause direct life loss,but also damage the subway structure and lead to further loss of lives and properties.The propagation law of explosion wave in the subway station was analyzed and a simplified model of overpressure in the subway station was also proposed.Whereafter,the improved dynamic cam-clay model of soil and the concrete damaged plasticity constitutive model were used for the dynamic analysis of the subway station.Meanwhile,the influences of soil stiffness and burial depth on the dynamic response of the subway station were looked into.The results show that the multi-peak overpressure in the subway station does not appear,and large stresses concentrate on the central column and the floor slab of the subway station,so some special reinforcement measures should be taken in these parts.The effect of soil stiffness and burial depth on the stress of the central column is little;however,the effect on the stress of the station side wall is relatively obvious.展开更多
Irregular columnar jointed structure is a primary irregular columnar morphological tensile fracture. In order to study the geometric features of irregular columnar joints and the new problems in geotechnical engineeri...Irregular columnar jointed structure is a primary irregular columnar morphological tensile fracture. In order to study the geometric features of irregular columnar joints and the new problems in geotechnical engineering, hydraulic and hydropower engineering caused by columnar jointed basaltic mass, Voronoi graph from geometry was introduced to simulate the irregular columnar jointed basaltic mass at Baihetan hydraulic station. Discrete element software UDEC was used to simulate the whole process of rigid bearing plate test. Anisotropic constitutive of columnar joints was adopted to analyze the stress diffusion of rock mass at dam base of Baihetan. The results show that, the compaction property and hysteresis effect are well simulated based on discrete element simulation of Voronoi joint structure by UDEC. Four stages of cyclic loading and unloading process are imaged clearly. The results from in situ rigid bearing plate tests are explicated and the stress diffusion rule of anisotropic body is affected by structure surface. The elements in the stress state of 4-5 MPa are the most, about more than 35% of the total. Appropriate constitutive must be proposed to columnar jointed rock mass with different styles. It has important significance to realize the nonlinear mechanical behavior of irregular columnar jointed basaltic mass.展开更多
A physical modeling case study on flood and sediment disaster of waterpower stations in mountain rivers was conducted.Field observations and laboratory experiments show that the reasons induced disasters of Boluo Wate...A physical modeling case study on flood and sediment disaster of waterpower stations in mountain rivers was conducted.Field observations and laboratory experiments show that the reasons induced disasters of Boluo Waterpower Station are those main characteristics of mountain rivers in South-Western China.High speed flows with velocities between 10 to 20 m/s are provided with strong sediment canting capacity in flood season.Steep banks with thick loose surfaces are rich in sediment supply by landslides and...展开更多
Tianhe Core Module of China Space Station(CSS)equips a set of instruments consisting of a Particle Fluxes and Solar Activity Detector(PFSAD)and two Atmospheric Density Multi-directional Detectors(ADMDs).The PFSAD is t...Tianhe Core Module of China Space Station(CSS)equips a set of instruments consisting of a Particle Fluxes and Solar Activity Detector(PFSAD)and two Atmospheric Density Multi-directional Detectors(ADMDs).The PFSAD is to measure X-rays from the Sun and energetic particles in the low-latitude and low altitude regions,including electrons,protons,and helium ions.The ADMDs are to measure thermospheric atmospheric density.The instruments provide real-time data of the orbital space environment,including solar flares,energetic particle variation and thermospheric density enhancement.All the data contribute to the CSS space weather service for mission control and astronaut’s safety.The paper gives preliminary analyses of the space environment measurements from the PFSAD and the ADMDs.By further analysis,the 1024-channel fine spectra of the solar X-ray can be used to study the mechanism of solar flares and their impacts on the Earth’s atmosphere.Data accumulation will be helpful for analyzing mid-term and long-term variations of the South Atlantic Anomaly and atmosphere density.Furthermore,the data are useful to calibrate previous empirical models and establish new models to study the space environment.展开更多
Taking the development of high-speed railway in China as background, and referring to the dynamic theory and wheel-rail contact mode, dynamic analysis model was established, considering the setting position of straigh...Taking the development of high-speed railway in China as background, and referring to the dynamic theory and wheel-rail contact mode, dynamic analysis model was established, considering the setting position of straight lines and running conditions of train in high-speed railway station yard. Using the established model, and choosing vehicle lateral acceleration and wheel suspension as the evaluation indexes, dynamic characteristic of vehicle traveling in turnout and adjacent area on main line was analyzed, and effects on travelling safety and stability of train aroused by length variation of straight lines were calculated based on analyzing the damping rules of vibration. The results show that, a certain length of straight lines can alleviate the vibration aroused in turnout and curve(turnout), length of straight lines connecting turnouts in different sections on main line was proposed to meet the demand of traveling stability, and shortening or cancelation of straight line for the scale limitation of station yard has less influence on operation safety of train.展开更多
Sediment deposition in the pumping station has a huge negative impact on unit operation.The three-dimensional CFD method has been used to simulate inlet structure flow in pumping station based on the Eulerian solid- l...Sediment deposition in the pumping station has a huge negative impact on unit operation.The three-dimensional CFD method has been used to simulate inlet structure flow in pumping station based on the Eulerian solid- liquid two-phase flow model. The numerical results of the preliminary scheme show that sediment deposition occurs in the forebay of pumping station because of poor flow pattern therein. In order to improve hydraulic configuration in the forebay,one modified measure reconstructs water diversion weir shape,and another measure sets a water retaining sill in the approach channel. The simulation results of the modified scheme prove that back flow in the forebay has been eliminated and the sediment deposition region has also been reduced.展开更多
Project significance Xiamen metro Line#3 runs from Xiamen Railway Station to Xiangran Airport.It is the southwest-northeast trunk line that connects the main island and the subcentre in the eastern regions(Xiangran Di...Project significance Xiamen metro Line#3 runs from Xiamen Railway Station to Xiangran Airport.It is the southwest-northeast trunk line that connects the main island and the subcentre in the eastern regions(Xiangran District).The Wuliu Section(the sea-crossing section from Wuyuan Bay Station to Liuwudian Station)is the main engineering feat of the metro line due to its high construction difficulty and tight schedule.As one of the earliest sea-crossing metro tunnels constructed in China,this project represents significant engineering achievements and innovations.The plane view of Wuliu Section is shown in Fig.1.2 Brief introduction of the project 2.1 Design overview The Wuliu Section of Xiamen Metro Line#3 crosses the Xiamen east sea area and connects the main island with Xiangran Dis trict.It is to the northwest of the Xiangran subsea tunnel.The total length the section is 4.95 km,including about 3.6 km of sea-crossing section.The maximum water depth is 25 m and the maximum buried depth of the tunnel is 69 m.It adopts a single-line,dual-bore section and uses the combined M mining method-shield method"construction technique.There are one inclined construction shaft,one air shaft,ten service channels,three wastewater pump houses and one power substation.The plane view of the tunnel is shown in Fig.2.展开更多
基金Entrusted Fund of National Institute of Information and Communications Technology(NICT),Japan(JPJ012368C02401)。
文摘The microwave wireless power transmission technologies for space solar power station are a crucial field in the international space sector,where various countries are competing in its development.This paper surveys the research experiments and development efforts related to space solar power stations and microwave wireless power transmission technologies worldwide.The objective is to assess the progress and current state of this technological foundation,determine the necessary focus for developing high-power microwave wireless power transmission technology,and provide clarity on the direction of future technology development in these areas.Finally,a distributed space solar power station plan that is immediately feasible is proposed.
基金Projects(RCS2015ZZ002,RCS2014ZT25)supported by State Key Laboratory of Rail Traffic Control&Safety,ChinaProject(2015RC058)supported by Beijing Jiaotong University,China
文摘Metro passenger flow control problem is studied under given total inbound demand in this work,which considers passenger demand control and train capacity supply.Relevant connotations are analyzed and a mathematical model is developed.The decision variables are boarding limiting and stop-skipping strategies and the objective is the maximal passenger profit.And a passenger original station choice model based on utility theory is built to modify the inbound passenger distribution among stations.Algorithm of metro passenger flow control scheme is designed,where two key technologies of stopping-station choice and headway adjustment are given and boarding limiting and train stopping-station scheme are optimized.Finally,a real case of Beijing metro is taken for example to verify validity.The results show that in the three scenarios with different ratios of normal trains to stop-skipping trains,the total limited passenger volume is the smallest and the systematic profit is the largest in scenario 3.
基金Project(50938008)supported by the Natural Science Foundation of Beijing,ChinaProject(2012JBM007)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(NCET-11-0571)supported by the Program for New Century Excellent Talents in University,China
文摘Results of in-situ vibration measurement carried out at Tianjin West Elevated Railway Station which has the trains running on the station structure were reported. The main excitation source is the train passing through the station. Vibration measurements were recorded in the vertical direction of the supporting track beam, the platform and the steel truss beam of the waiting hall, as well as in the vertical, longitudinal and transverse directions of the roof arch base of the station. Acceleration time responses were obtained. The maximum value, vibration level and one-third octave band RMS spectra of the measured accelerations were studied. The propagation of vibration in different structural floors was discussed. The influence of train speed, distance to the vibration source and the type of train on the structural vibration were analyzed. Results show that the vibration level increases with the train speed, while it attenuates with the distance to the track. Furthermore, the vibration responses of different structural floors were compared, and it is noted that the vertical vibration of the bottom slab of the platform is most severe and the transverse vibration of the roof arch base is the smallest. The results provide reference on the vibration characteristics and vibration energy distribution of this type of "Train on building frame" system used as an elevated railway station.
文摘The core module of China’s Space Station(CSS)is scheduled to be launched around the end of 2020,and the experimental module I and II will be launched in the next two years.After on-orbit constructions,CSS will be transferred into an operation period over 10 years(2022–2032 and beyond)to continuously implement space science missions.At present,based on the project selection and research work in the ground development period of CSS,China is systematically making a utilization mission planning for the operation period,which focuses on the fields of aerospace medicine and human research,space life science and biotechnology,microgravity fluid physics,combustion science,materials science,fundamental physics,space astronomy and astrophysics,Earth science,space physics and space environment,space application technology,etc.In combination with the latest development trend of space science and technology,China will continue to update planning for science research and technology development,carry out project cultivation,payload R&D,and upgrade onboard and ground experiment supporting systems to achieve greater comprehensive benefits in science,technology,economy,and society。
基金Supported by National Key Research and Development Program of China(2020YFE0202100)。
文摘China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar research station program,which aims to build a shared platform on the Moon jointly with many other countries for long-term and continuous lunar exploration,lunar-based observations and experiments,as well as in-situ resource utilization.In addition,China has also proposed an interstellar express mission to unveil the mysteries of the outer heliosphere,nearby interstellar space,and their interactions.This paper gives a brief introduction to the International Lunar Research Station program and the Interstellar Express mission.
基金Project(60873081)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0787)supported by Program for New Century Excellent Talents in UniversityProject(11JJ1012)supported by the Natural Science Foundation of Hunan Province,China
文摘The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytical method for avoiding energy hole was proposed. It is proved that if the densities of sensor nodes working at the same time are alternate between dormancy and work with non-uniform node distribution. The efficiency of network can increase by several times and the residual energy of network is nearly zero when the network lifetime ends.
文摘China scheduled to complete the assembly of the T-shaped Tiangong Space Station in 2022,and will enter a new stage of utilization.There are more than 20 experiment racks inside the modules,and more than 50 external onboard payloads mounting spaces,which will support large-scale science and technology experiments during the operation.The development of internal experiment racks and external research accommodations approved during the construction has been completed,of which 4 racks in Tianhe core module,including High Microgravity Level research Rack(HMLR)and Container-less Materials Processing Rack(CMPR),have finished on-orbit tests;while other racks in Wentian and Mengtian experiment modules are under comprehensive ground tests.The Chinese Space Survey Telescope(CSST)has advanced much in the last two years with 24 pre-launch research projects funded and 4 joint science center built in preparation for CSST’s future scientific observations and operations.The systematic research planning for China’s Space Station(CSS)during 2022-2032 is updated with the researches classified into four important areas:space life sciences and human research,microgravity physical sciences,space astronomy and Earth science,and new space technologies and applications.According to the planning,more than 1000 experiments are expected to perform in CSS during the operating period.Overall,the CSS utilization missions are proceeding as planned,which will contribute to the major scientific or application output and have a positive impact on the quality of life on Earth.
基金Project(2011BAG01B01)supported by the Key Technologies Research Development Program,ChinaProject(RCS2012ZZ002)supported by State Key Laboratory of Rail Traffic Control&Safety,China
文摘The major objective of this work was to calculate evacuation capacity and solve the optimal routing problem in a given station topology from a network optimization perspective where station facilities were modelled as open finite queueing networks with a multi-objective set of performance measures. The optimal routing problem was determined so that the number of evacuation passengers was maximized while the service level was higher than a certain criterion. An analytical technique for modelling open finite queueing networks, called the iteration generalized expansion method(IGEM), was utilized to calculate the desired outputs. A differential evolution algorithm was presented for determining the optimal routes. As demonstrated, the design methodology which combines the optimization and analytical queueing network models provides a very effective procedure for simultaneously determining the service level and the maximum number of evacuation passengers in the best evacuation routes.
基金Project(2011FZ050) supported by the Applied Basic Research Program of Yunnan Provincial Science and Technology Department,ChinaProject(2011J084) supported by the Master Program of Yunnan Province Education Department,China
文摘Organic Rankine cycle(ORC) power plant operating with supercritical parameters supplied by low temperature slag-washing water(SWW) of blast furnace was investigated.A schematic of such installation was presented with a description of its operation and the algorithm of calculations of a supercritical power plant.Two typical organic fluids with sufficiently low critical parameters were selected as candidate working fluids in the plant to study the efficiency of the system with different organic fluids.An analysis of the influence on the effectiveness of operation of a plant was carried out.With the same temperature of slag-washing water,the specific work in turbine of fluid R143a is 45% higher than that obtained for the fluid R125,however,the specific work in pump of fluid R143a is approximate equal into that one of the fluid R125.
基金supported by the National Natural Science Foundation of China(11402295)the Science Project of National University of Defense Technology(JC14-01-05)the Hunan Provincial Natural Science Foundation of China(2015JJ3020)
文摘This paper studies the problem of the space station short-term mission planning, which aims to allocate the executing time of missions effectively, schedule the corresponding resources reasonably and arrange the time of the astronauts properly. A domain model is developed by using the ontology theory to describe the concepts, constraints and relations of the planning domain formally, abstractly and normatively. A method based on time iteration is adopted to solve the short-term planning problem. Meanwhile, the resolving strategies are proposed to resolve different kinds of conflicts induced by the constraints of power, heat, resource, astronaut and relationship. The proposed approach is evaluated in a test case with fifteen missions, thirteen resources and three astronauts. The results show that the developed domain ontology model is reasonable, and the time iteration method using the proposed resolving strategies can successfully obtain the plan satisfying all considered constraints.
文摘Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as space life science and biotechnology,space materials science,microgravity fundamental physics,fluid physics,combustion science,space new technologies,and applications.In this review,we introduce the progress of CSS development and provide an overview of the research conducted in Chinese Space Station and the recent scientific findings in several typical research fields.Such compelling findings mainly concern the rapid solidification of ultra-high temperature alloy melts,dynamics of fluid transport in space,gravity scaling law of boiling heat transfer,vibration fluidization phenomenon of particulate matter,cold atom interferometer technology under high microgravity and related equivalence principle testing,the full life cycle of rice under microgravity and so forth.Furthermore,the planned scientific research and corresponding prospects of Chinese space station in the next few years are presented.
基金Project(50978043) supported by the National Natural Science Foundation of China
文摘The study was motivated by the fact that explosion inside the subway structure may not only cause direct life loss,but also damage the subway structure and lead to further loss of lives and properties.The propagation law of explosion wave in the subway station was analyzed and a simplified model of overpressure in the subway station was also proposed.Whereafter,the improved dynamic cam-clay model of soil and the concrete damaged plasticity constitutive model were used for the dynamic analysis of the subway station.Meanwhile,the influences of soil stiffness and burial depth on the dynamic response of the subway station were looked into.The results show that the multi-peak overpressure in the subway station does not appear,and large stresses concentrate on the central column and the floor slab of the subway station,so some special reinforcement measures should be taken in these parts.The effect of soil stiffness and burial depth on the stress of the central column is little;however,the effect on the stress of the station side wall is relatively obvious.
基金Projects(50979030, 50911130366) supported by the National Natural Science Foundation of ChinaProject(2009B14014) supported by the Fundamental Research Funds for the Central Universities in China
文摘Irregular columnar jointed structure is a primary irregular columnar morphological tensile fracture. In order to study the geometric features of irregular columnar joints and the new problems in geotechnical engineering, hydraulic and hydropower engineering caused by columnar jointed basaltic mass, Voronoi graph from geometry was introduced to simulate the irregular columnar jointed basaltic mass at Baihetan hydraulic station. Discrete element software UDEC was used to simulate the whole process of rigid bearing plate test. Anisotropic constitutive of columnar joints was adopted to analyze the stress diffusion of rock mass at dam base of Baihetan. The results show that, the compaction property and hysteresis effect are well simulated based on discrete element simulation of Voronoi joint structure by UDEC. Four stages of cyclic loading and unloading process are imaged clearly. The results from in situ rigid bearing plate tests are explicated and the stress diffusion rule of anisotropic body is affected by structure surface. The elements in the stress state of 4-5 MPa are the most, about more than 35% of the total. Appropriate constitutive must be proposed to columnar jointed rock mass with different styles. It has important significance to realize the nonlinear mechanical behavior of irregular columnar jointed basaltic mass.
基金Supported by 973 Program of China(2003CB415202),and by Key Project of Chinese Ministry of Education(03134).
文摘A physical modeling case study on flood and sediment disaster of waterpower stations in mountain rivers was conducted.Field observations and laboratory experiments show that the reasons induced disasters of Boluo Waterpower Station are those main characteristics of mountain rivers in South-Western China.High speed flows with velocities between 10 to 20 m/s are provided with strong sediment canting capacity in flood season.Steep banks with thick loose surfaces are rich in sediment supply by landslides and...
文摘Tianhe Core Module of China Space Station(CSS)equips a set of instruments consisting of a Particle Fluxes and Solar Activity Detector(PFSAD)and two Atmospheric Density Multi-directional Detectors(ADMDs).The PFSAD is to measure X-rays from the Sun and energetic particles in the low-latitude and low altitude regions,including electrons,protons,and helium ions.The ADMDs are to measure thermospheric atmospheric density.The instruments provide real-time data of the orbital space environment,including solar flares,energetic particle variation and thermospheric density enhancement.All the data contribute to the CSS space weather service for mission control and astronaut’s safety.The paper gives preliminary analyses of the space environment measurements from the PFSAD and the ADMDs.By further analysis,the 1024-channel fine spectra of the solar X-ray can be used to study the mechanism of solar flares and their impacts on the Earth’s atmosphere.Data accumulation will be helpful for analyzing mid-term and long-term variations of the South Atlantic Anomaly and atmosphere density.Furthermore,the data are useful to calibrate previous empirical models and establish new models to study the space environment.
基金Project(2014JBZ012)supported by the Fundamental Research Funds for the Central Universities,China
文摘Taking the development of high-speed railway in China as background, and referring to the dynamic theory and wheel-rail contact mode, dynamic analysis model was established, considering the setting position of straight lines and running conditions of train in high-speed railway station yard. Using the established model, and choosing vehicle lateral acceleration and wheel suspension as the evaluation indexes, dynamic characteristic of vehicle traveling in turnout and adjacent area on main line was analyzed, and effects on travelling safety and stability of train aroused by length variation of straight lines were calculated based on analyzing the damping rules of vibration. The results show that, a certain length of straight lines can alleviate the vibration aroused in turnout and curve(turnout), length of straight lines connecting turnouts in different sections on main line was proposed to meet the demand of traveling stability, and shortening or cancelation of straight line for the scale limitation of station yard has less influence on operation safety of train.
基金Chinese National Foundation of Natural Science-Key Projects(51339005)
文摘Sediment deposition in the pumping station has a huge negative impact on unit operation.The three-dimensional CFD method has been used to simulate inlet structure flow in pumping station based on the Eulerian solid- liquid two-phase flow model. The numerical results of the preliminary scheme show that sediment deposition occurs in the forebay of pumping station because of poor flow pattern therein. In order to improve hydraulic configuration in the forebay,one modified measure reconstructs water diversion weir shape,and another measure sets a water retaining sill in the approach channel. The simulation results of the modified scheme prove that back flow in the forebay has been eliminated and the sediment deposition region has also been reduced.
文摘Project significance Xiamen metro Line#3 runs from Xiamen Railway Station to Xiangran Airport.It is the southwest-northeast trunk line that connects the main island and the subcentre in the eastern regions(Xiangran District).The Wuliu Section(the sea-crossing section from Wuyuan Bay Station to Liuwudian Station)is the main engineering feat of the metro line due to its high construction difficulty and tight schedule.As one of the earliest sea-crossing metro tunnels constructed in China,this project represents significant engineering achievements and innovations.The plane view of Wuliu Section is shown in Fig.1.2 Brief introduction of the project 2.1 Design overview The Wuliu Section of Xiamen Metro Line#3 crosses the Xiamen east sea area and connects the main island with Xiangran Dis trict.It is to the northwest of the Xiangran subsea tunnel.The total length the section is 4.95 km,including about 3.6 km of sea-crossing section.The maximum water depth is 25 m and the maximum buried depth of the tunnel is 69 m.It adopts a single-line,dual-bore section and uses the combined M mining method-shield method"construction technique.There are one inclined construction shaft,one air shaft,ten service channels,three wastewater pump houses and one power substation.The plane view of the tunnel is shown in Fig.2.
