A nine-layer spectral atmospheric general circulation model is coupled to a twenty-layer global oceanic general circulation model with the“prediction-correction”monthly anomaly exchange scheme which has been propose...A nine-layer spectral atmospheric general circulation model is coupled to a twenty-layer global oceanic general circulation model with the“prediction-correction”monthly anomaly exchange scheme which has been proposed at the Institute of Atmospheric Physics (IAP). A forty-year integration of the coupled model shows that the CGCM is fairly successful in keeping a reasonable pattern of the modelled SST although most of the Pacific become warmer than those given by the uncoupled ocean model. The model tends to reach a more realistic state than the uncoupled one in terms of downward surface heat flux into ocean particularly in the equatorial Pacific region. Also, the model is capable to simulate interannual variability of sea surface temperature in tropical region.展开更多
Distributed Electric Propulsion(DEP)aircraft use multiple electric motors to drive the propulsors,which gives potential benefits to aerodynamic-propulsion interaction.To investigate and quantify the aerodynamic-propul...Distributed Electric Propulsion(DEP)aircraft use multiple electric motors to drive the propulsors,which gives potential benefits to aerodynamic-propulsion interaction.To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section,we built a DEP demonstrator with 24"high-lift"Electric Ducted Fans(EDFs)distributed along the wing’s trailing edge.This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed,throttle,and EDF mounting surface deflection angles using a series of wind tunnel tests.We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15-25 m/s freestream flow and angles of attack from-4°to 16°.The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration.The results show that the EDFs can produce significant lift increment and drag reduction simultaneously,which is accordant with the potential benefit of Boundary Layer Ingestion(BLI)at low airspeed.展开更多
We take the established inductively coupled plasma(ICP) wind tunnel as a research object to investigate the thermal protection system of re-entry vehicles. A 1.2-MW high power ICP wind tunnel is studied through numeri...We take the established inductively coupled plasma(ICP) wind tunnel as a research object to investigate the thermal protection system of re-entry vehicles. A 1.2-MW high power ICP wind tunnel is studied through numerical simulation and experimental validation. The distribution characteristics and interaction mechanism of the flow field and electromagnetic field of the ICP wind tunnel are investigated using the multi-field coupling method of flow, electromagnetic, chemical, and thermodynamic field. The accuracy of the numerical simulation is validated by comparing the experimental results with the simulation results. Thereafter, the wind tunnel pressure, air velocity, electron density, Joule heating rate, Lorentz force, and electric field intensity obtained using the simulation are analyzed and discussed. The results indicate that for the 1.2-MW ICP wind tunnel, the maximum values of temperature, pressure, electron number density, and other parameters are observed during coil heating. The influence of the radial Lorentz force on the momentum transfer is stronger than that of the axial Lorentz force. The electron number density at the central axis and the amplitude and position of the Joule heating rate are affected by the radial Lorentz force. Moreover, the plasma in the wind tunnel is constantly in the subsonic flow state, and a strong eddy flow is easily generated at the inlet of the wind tunnel.展开更多
At the Mont Terri Underground Research Laboratory （Switzerland）, a field-scale investigation has been conducted in order to investigate the hydro-mechanical and chemical perturbations induced in the argilla- ceous f...At the Mont Terri Underground Research Laboratory （Switzerland）, a field-scale investigation has been conducted in order to investigate the hydro-mechanical and chemical perturbations induced in the argilla- ceous formation by forced ventilation through a tunnel. This experiment has been selected to be used for processing model development and validation in the international project DECOVALEX-2011. The con- ceptual and mathematical representation of the engineered void, which itself forms a major part of the experiment and is not simply a boundary condition, is the subject of this paper. A variety of approaches have been examined by the contributors to DECOVALEX and a summary of their findings is presented here. Two major aspects are discussed. Firstly, the approaches for the treatment of the surface condition at the porous media/tunnel interface are examined, with two equivalent but differing formulations successfully demonstrated. Secondly, approaches for representing the tunnel with associated air and water vapour movement, when coupled with the hydro-mechanical （HM） representation of the porous medium, are also examined. It is clearly demonstrated that, for the experimental conditions of the ventilation experiment （VE） that abstracted physical and empirical models of the tunnel, can be used successfully to represent the hydraulic behaviour of the tunnel and the hydraulic interaction between the tunnel and the surrounding rock mass.展开更多
In this paper, the coupled thermo-mechanical （TM） processes in the AEspoe Pillar Stability Experiment （APSE） carried out by the Swedish Nuclear Fuel and Waste Management Company （SKB） were simulated using both c...In this paper, the coupled thermo-mechanical （TM） processes in the AEspoe Pillar Stability Experiment （APSE） carried out by the Swedish Nuclear Fuel and Waste Management Company （SKB） were simulated using both continuum and discontinuum based numerical methods. Two-dimensional （2D） and three- dimensional （3D） finite element method （FEM） and 2D distinct element method （DEM） with particles were used. The main objective for the large scale in situ experiment is to investigate the yielding strength of crystalline rock and the formation of the excavation disturbed/damaged zone （EDZ） during excavation of two boreholes, pressurizing of one of the boreholes and heating. For the DEM simulations, the heat flow algorithm was newly introduced into the original code. The calculated stress, displacement and temperature distributions were compared with the ones obtained from in situ measurements and FEM simulations. A parametric study for initial microcracks was also performed to reproduce the spalling phenomena observed in the APSE.展开更多
This paper presents a study of the full three-dimensional thermo-mechanical （TM） behavior of rock pillar in,Aspo Pillar Stability Experiment （APSE） using a self-developed numerical code TM-EPCA3D. The transient th...This paper presents a study of the full three-dimensional thermo-mechanical （TM） behavior of rock pillar in,Aspo Pillar Stability Experiment （APSE） using a self-developed numerical code TM-EPCA3D. The transient thermal conduction function was descritized on space and time scales, and was solved by using cellular automaton （CA） method on space scale and finite difference method on time scale, respectively. The advantage of this approach is that no global, but local matrix is used so that it avoids the need to develop and solve large-scale linear equations and the complexity therein. A thermal conductivity versus stress function was proposed to reflect the effect of stress on thermal field. The temperature evolution and induced thermal stress in the pillar part during the heating and cooling processes were well simulated by the developed code. The factors that affect the modeling results were discussed. It is concluded that, the complex TM behavior of Aspo rock pillar is significantly influenced by the complex boundary and initial conditions.展开更多
A group of seasonal hindcast experiments are conducted using a coupled model known as the Flexible Global Ocean-Atmosphere-Land System Modelgamil1.11 (FGOALS-g1.11) developed at the State Key Laboratory of Numerical M...A group of seasonal hindcast experiments are conducted using a coupled model known as the Flexible Global Ocean-Atmosphere-Land System Modelgamil1.11 (FGOALS-g1.11) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG).Two steps are included in our ElNi o-Southern Oscillation (ENSO) hindcast experiments.The first step is to integrate the coupled GCM with the Sea Surface Temperature (SST) strongly nudged towards the observation from 1971 to 2006.The second step is to remove the SST nudging term.The authors carried out a one-year hindcast by adopting the initial values from SST nudging experiments from the first step on January 1st,April 1st,July 1st,and October 1st from 1982 to 2005.In the SST nudging experiment,the model can reproduce the observed equatorial thermocline anomalies and zonal wind stress anomalies in the Pacific,which demonstrates that the SST nudging approach can provide realistic atmospheric and oceanic initial conditions for seasonal prediction experiments.The model also demonstrates a high Anomaly Correlation Coefficient (ACC) score for SST in most of the tropical Pacific,Atlantic Ocean,and some Indian Ocean regions with a 3-month lead.Compared with the persistence ACC score,this model shows much higher ACC scores for the Ni o-3.4 index for a 9-month lead.展开更多
Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of...Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol （Cinnamon soil）, with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence （F0） of leaves was higher in the dry treatment （0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity） compared to the wet treatment （entire soil column at 75-80% of field capacity）. The maximal fluorescence （Fm）, the variable fluorescence （Fv）, the photochemical efficiency （Fv/Fm） and potential activites （Fv/F0） of photosystem 2 （PS2） were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased FJFm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 em of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and F,fFm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants FJFm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.展开更多
Two land surface schemes, one the standard Biosphere / Atmosphere Transfer Scheme Version ie (BOZ) and the other B1Z based on B0Z and heterogeneously-treated by' combined approach' , were co 'pled to the m...Two land surface schemes, one the standard Biosphere / Atmosphere Transfer Scheme Version ie (BOZ) and the other B1Z based on B0Z and heterogeneously-treated by' combined approach' , were co 'pled to the meso-scale model MM4, respectively. Through the calculations of equations from the companion paper, parameters representing land surface heterogeneity and suitable for the coupling models were found out. Three cases were simulated for heavy rainfalls during 36 hours, and the sensitivity of short-term weather modeling to the land surface heterogeneity was tested. Through the analysis of the simulations of the three heavy rainfalls, it was demonstrated that BIZ, compared with BOZ, could more realistically reflect the features of the land surface heterogeneity, therefore could more realistically reproduce the circulation and precipitation amount in the heavy rainfall processes of the three cases. This shows that even short-term weather is sensitive to the land surface heterogeneity, which is more obvious with time passing, and whose influence is more pronounced in the lower layer and gradually extends to the middle and upper layer. Through the analysis of these simulations with BlZ, it is suggested that the bulk effect of smaller-scale fluxes (i.e., the momentum, water vapor and sensible heat fluxes) near the s ig nificantly-heterogeneous land surface is to change the larger-scale (i.e., meso-scale) circulation, and then to influence the development of the low-level jets and precipitation. And also, the complexity of the land-atmosphere interaction was shown in these simulations.展开更多
The floating foundation is designed to support a 1.5 MW wind turbine in 30 m water depth. With consideration of the viscous damping of foundation and heave plates, the amplitude-frequency response characteristics of t...The floating foundation is designed to support a 1.5 MW wind turbine in 30 m water depth. With consideration of the viscous damping of foundation and heave plates, the amplitude-frequency response characteristics of the foundation are studied. By taking into account the elastic effect of blades and tower, the classic quasi-steady blade-element/momentum（BEM） theory is used to calculate the aerodynamic elastic loads. A coupled dynamic model of the turbine-foundationmooring lines is established to calculate the motion response of floating foundation under Kaimal wind spectrum and regular wave by using the FAST codes. The model experiment is carried out to test damping characteristics and natural motion behaviors of the wind turbine system. The dynamics response is tested by considering only waves and the joint action of wind and waves. It is shown that the wind turbine system can avoid resonances under the action of wind and waves. In addition, the heave motion of the floating foundation is induced by waves and the surge motion is induced by wind. The action of wind and waves is of significance for pitch.展开更多
The effects of toughener and coupling agent on special epoxy silicone adhesive were discussed by researching the surface morphology characters, thermal properties and shear strength of the adhesive. The results indica...The effects of toughener and coupling agent on special epoxy silicone adhesive were discussed by researching the surface morphology characters, thermal properties and shear strength of the adhesive. The results indicate that silicone coupling agent (KH-550) can improve the shear strength of the epoxy silicone adhesive effectively. The mass fraction of the toughener in the epoxy silicone adhesive plays an important role in its properties. When the mass fraction of the toughener is less than 14%, the shear strength of the adhesive is low. When the mass fraction of the toughener is over 33%, thermal properties and shear strength of the adhesive decrease with the increasing of the toughener. The mass fraction of toughener of 25% results in good integral properties of the epoxy silicone adhesive. The morphologic analysis indicates that the micro-phase separation exists in the epoxy molecular chain and the silicone molecular chain of the epoxy silicone adhesive.展开更多
The first-order approximation coupling （FOAC） model was proposed recently for dynamics and control of flexible hub-beam systems. This model may deal with system dynamics for both low and high rotation speed, while t...The first-order approximation coupling （FOAC） model was proposed recently for dynamics and control of flexible hub-beam systems. This model may deal with system dynamics for both low and high rotation speed, while the classical zeroth-order approximation coupling （ZOAC） model is only available for low rotation speed. This paper assumes the FOAC model to present experimental study of active positioning control of a flexible hub-beam system. Linearization and nonlinear control strategies are both considered. An experiment system based on a DSP TMS320F2812 board is introduced. The difference between linearization and nonlinear control strategies are studied both numerically and experimentally. Simulation and experimental results indicate that, linearized controller can make the system reach an expected position with suppressed vibration of flexible beam, but the time taken to position is longer than expected, whereas nonlinear controller works well with precise positioning, suppression of vibration and time control.展开更多
By using the experimental approach of dropping liquid, the coupling of three anionic wetting agents with ten dust samples of sulfide ores was studied, and particularly the wetting effects of the wetting agents on the ...By using the experimental approach of dropping liquid, the coupling of three anionic wetting agents with ten dust samples of sulfide ores was studied, and particularly the wetting effects of the wetting agents on the sulfide dust influenced by factors of agent concentration and sulfate additive in the wetting agent solutions were investigated. The results show that when the solution temperature is about 20 ℃, all the selected wetting agents are effective to most dust samples, but the effect is different. Wetting agents are more effective to the dust which is difficult to be wetted. Wetting agent solution with sodium sulfate can improve the wetting ability of sulfide dust. For sodium dodecyl benzene sulfonate, the suitable concentration of sodium sulfate is 12 mmol/L. The cost of wetting agents can be reduced because the sodium sulfate is much cheaper than many surfactants. Since the dust of sulfide ores is composed of various minerals and elements, the whole effect of depressing dust should be considered while innovating a wetting agent.展开更多
This paper puts forward a new rock fragmentation loading method of dual-cutter head combined dynamic and static loads. By applying the numerical simulation software - RFPA2D, we have done numerical experiment about th...This paper puts forward a new rock fragmentation loading method of dual-cutter head combined dynamic and static loads. By applying the numerical simulation software - RFPA2D, we have done numerical experiment about the sihstone＇ s crushing effect by dynamic load on single cutter head without confining pressure, dynamic load on single cut- ter head with confining pressure 10 MPa and different dual-cutter heads spacing by combined dynamic and static loads with confining pressure 10 MPa. Experimental results show that the confining pressure can obviously affect the rock frag- mentation effect. Combined dynamic and static loads can greatly improve the rock fragmentation effect. There exists an optimal spacing of dual-cutter head that can make the rock fragmentation achieve the desired effect. Through analyzing the acoustic emission accumulative energy and quantity, the authors make a conclusion that the optimum spacing is 30 mm.展开更多
Experiments of silt rock subjected to coupling loads were carried out on tailormade equipment. With a constant dynamic load, the behaviors of eight sets of siltite specimens were investigated with different axial stat...Experiments of silt rock subjected to coupling loads were carried out on tailormade equipment. With a constant dynamic load, the behaviors of eight sets of siltite specimens were investigated with different axial static loads. The experimental results show that the modulus of the specimens under coupling loads increases at first and then decreases with the increase of axial static pressure. The failure model of the specimens also varies. Keeping the dynamic load constant, when the axial static pressure is low, the specimen breaks in two simply. With the increase of axial static pressure, the cone-shaped fragment appeares. When the axial static pressure reaches 90% of the static strength of rock, the specimen smashes into amount of small fragments.展开更多
The research on structural vibration and sound radiation of underwater ring-ribbed cylindrical shell,which is coated with a kind of deadening and decoupling materials,becomes a focus in recent years.This paper analyze...The research on structural vibration and sound radiation of underwater ring-ribbed cylindrical shell,which is coated with a kind of deadening and decoupling materials,becomes a focus in recent years.This paper analyzes the problem on two aspects:model experiment and numerical calculation.The model experiment is carried out including three cases firstly,in which the structural vibration response and radiating acoustic field are measured respectively,and the results gained in these three cases are analyzed to discuss the effect of reducing structural vibration and radiating noise of the deadening and decoupling materials.The coupling FEM/BEM and the SEA methods are both used in numerical calculation,i.e.the arithmetic of the coupling FEM/BEM method is adopted to calculate the low frequency characteristics and the SEA method is adopted to calculate the medium-high frequencies characteristics of the model.By comparing experimental results with numerical calculation results,it is proved that the algorithm adopted in this paper is reasonable.展开更多
To address issues such as suboptimal separation of potatoes from soil during harvest,weak damage prevention and reduction capabilities in the transport process,and high damage rates,a potato-soil-transport device moti...To address issues such as suboptimal separation of potatoes from soil during harvest,weak damage prevention and reduction capabilities in the transport process,and high damage rates,a potato-soil-transport device motion model was proposed based on potato farming practices in northern China(Gansu).The mechanical properties of the separation and transport device and the movement mechanism of the potatoes were analyzed,identifying key factors affecting the separation efficiency of potatoes from soil and potato damage:separation transport device inclination angle(ɑ),machine forward speed(V_(m)),paddle wheel amplitude(A),and paddle wheel frequency(ƒ).A coupled RecurDyn-EDEM simulation model was constructed to determine the impact of key factors on soil separation efficiency and potato damage.Using an optimization method,the optimal parameter combination for evaluating potato-soil separation was determined:separation transport device inclination angle of 18°,machine forward speed of 4.7 km/h,paddle wheel amplitude of 32.8 mm,and paddle wheel frequency of 6.0 Hz.Field tests showed that the potato-soil separation efficiency was good,with potatoes containing minimal soil and other impurities and experiencing minimal damage.The average potato-soil separation efficiency was 96%,and the average potato damage rate was 2%.Compared to the simulation results,the errors were 0.47%and 0.3%,respectively,meeting the quality requirements for potato harvesting operations.展开更多
文摘A nine-layer spectral atmospheric general circulation model is coupled to a twenty-layer global oceanic general circulation model with the“prediction-correction”monthly anomaly exchange scheme which has been proposed at the Institute of Atmospheric Physics (IAP). A forty-year integration of the coupled model shows that the CGCM is fairly successful in keeping a reasonable pattern of the modelled SST although most of the Pacific become warmer than those given by the uncoupled ocean model. The model tends to reach a more realistic state than the uncoupled one in terms of downward surface heat flux into ocean particularly in the equatorial Pacific region. Also, the model is capable to simulate interannual variability of sea surface temperature in tropical region.
基金supported by the National Natural Science Foundation of China(No.51877178)。
文摘Distributed Electric Propulsion(DEP)aircraft use multiple electric motors to drive the propulsors,which gives potential benefits to aerodynamic-propulsion interaction.To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section,we built a DEP demonstrator with 24"high-lift"Electric Ducted Fans(EDFs)distributed along the wing’s trailing edge.This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed,throttle,and EDF mounting surface deflection angles using a series of wind tunnel tests.We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15-25 m/s freestream flow and angles of attack from-4°to 16°.The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration.The results show that the EDFs can produce significant lift increment and drag reduction simultaneously,which is accordant with the potential benefit of Boundary Layer Ingestion(BLI)at low airspeed.
基金supported by the National Natural Science Foundation of China (Grant No. 11705143)the Open Foundation for Key Laboratories of National Defense Science and Technology of China (Grant No. 6142202031901)the Foundation for Research and Development of Applied Technology in Beilin District of Xi’an,China (Grant No. GX2047)。
文摘We take the established inductively coupled plasma(ICP) wind tunnel as a research object to investigate the thermal protection system of re-entry vehicles. A 1.2-MW high power ICP wind tunnel is studied through numerical simulation and experimental validation. The distribution characteristics and interaction mechanism of the flow field and electromagnetic field of the ICP wind tunnel are investigated using the multi-field coupling method of flow, electromagnetic, chemical, and thermodynamic field. The accuracy of the numerical simulation is validated by comparing the experimental results with the simulation results. Thereafter, the wind tunnel pressure, air velocity, electron density, Joule heating rate, Lorentz force, and electric field intensity obtained using the simulation are analyzed and discussed. The results indicate that for the 1.2-MW ICP wind tunnel, the maximum values of temperature, pressure, electron number density, and other parameters are observed during coil heating. The influence of the radial Lorentz force on the momentum transfer is stronger than that of the axial Lorentz force. The electron number density at the central axis and the amplitude and position of the Joule heating rate are affected by the radial Lorentz force. Moreover, the plasma in the wind tunnel is constantly in the subsonic flow state, and a strong eddy flow is easily generated at the inlet of the wind tunnel.
基金the context of the international DECOVALEX Project (DEmonstration of COupled models and their VALidation against EXperiments)EC project NF-PRO (Contract number FI6W-CT-2003-02389) under the coordination of ENRESA (Empresa Nacional de Residuos Radiactivos)
文摘At the Mont Terri Underground Research Laboratory （Switzerland）, a field-scale investigation has been conducted in order to investigate the hydro-mechanical and chemical perturbations induced in the argilla- ceous formation by forced ventilation through a tunnel. This experiment has been selected to be used for processing model development and validation in the international project DECOVALEX-2011. The con- ceptual and mathematical representation of the engineered void, which itself forms a major part of the experiment and is not simply a boundary condition, is the subject of this paper. A variety of approaches have been examined by the contributors to DECOVALEX and a summary of their findings is presented here. Two major aspects are discussed. Firstly, the approaches for the treatment of the surface condition at the porous media/tunnel interface are examined, with two equivalent but differing formulations successfully demonstrated. Secondly, approaches for representing the tunnel with associated air and water vapour movement, when coupled with the hydro-mechanical （HM） representation of the porous medium, are also examined. It is clearly demonstrated that, for the experimental conditions of the ventilation experiment （VE） that abstracted physical and empirical models of the tunnel, can be used successfully to represent the hydraulic behaviour of the tunnel and the hydraulic interaction between the tunnel and the surrounding rock mass.
基金conducted within the context of the international DECOVALEX Project (DEvelopment of COupled models and their VALidation against EXperiments)financed by Japan Atomic Energy Agency (JAEA) who was also one of the Funding Organizations of the projectChrister Anders-son from Swedish Nuclear Fuel and Waste Management Co.(SKB),Sweden
文摘In this paper, the coupled thermo-mechanical （TM） processes in the AEspoe Pillar Stability Experiment （APSE） carried out by the Swedish Nuclear Fuel and Waste Management Company （SKB） were simulated using both continuum and discontinuum based numerical methods. Two-dimensional （2D） and three- dimensional （3D） finite element method （FEM） and 2D distinct element method （DEM） with particles were used. The main objective for the large scale in situ experiment is to investigate the yielding strength of crystalline rock and the formation of the excavation disturbed/damaged zone （EDZ） during excavation of two boreholes, pressurizing of one of the boreholes and heating. For the DEM simulations, the heat flow algorithm was newly introduced into the original code. The calculated stress, displacement and temperature distributions were compared with the ones obtained from in situ measurements and FEM simulations. A parametric study for initial microcracks was also performed to reproduce the spalling phenomena observed in the APSE.
基金the context of the international DECOVALEX Project (DEmonstration of COupled models and their VALidation against EXperiments)grateful to the Institute of Rock and Soil Mechanics, Chinese Academy of Sciences (CAS), China, as one of the Funding Organizations of the project+2 种基金supported by a grant from the National Basic Research Program of China (No. 2010CB732006)the National Natural Science Foundation of China (Nos. 10972231, 41272349)SKB through its sp Pillar Stability Experiment project
文摘This paper presents a study of the full three-dimensional thermo-mechanical （TM） behavior of rock pillar in,Aspo Pillar Stability Experiment （APSE） using a self-developed numerical code TM-EPCA3D. The transient thermal conduction function was descritized on space and time scales, and was solved by using cellular automaton （CA） method on space scale and finite difference method on time scale, respectively. The advantage of this approach is that no global, but local matrix is used so that it avoids the need to develop and solve large-scale linear equations and the complexity therein. A thermal conductivity versus stress function was proposed to reflect the effect of stress on thermal field. The temperature evolution and induced thermal stress in the pillar part during the heating and cooling processes were well simulated by the developed code. The factors that affect the modeling results were discussed. It is concluded that, the complex TM behavior of Aspo rock pillar is significantly influenced by the complex boundary and initial conditions.
基金supported by the National Natural Science Foundation of China (No.40675049,No.40523001)NBRP (National Basic Research Program) "Ocean-Atmosphere Interaction over the Joining Area of Asia and Indian-Pacific Ocean (AIPO) and Its Impact on the Short-Term Climate Variation in China" (2006CB403605)
文摘A group of seasonal hindcast experiments are conducted using a coupled model known as the Flexible Global Ocean-Atmosphere-Land System Modelgamil1.11 (FGOALS-g1.11) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG).Two steps are included in our ElNi o-Southern Oscillation (ENSO) hindcast experiments.The first step is to integrate the coupled GCM with the Sea Surface Temperature (SST) strongly nudged towards the observation from 1971 to 2006.The second step is to remove the SST nudging term.The authors carried out a one-year hindcast by adopting the initial values from SST nudging experiments from the first step on January 1st,April 1st,July 1st,and October 1st from 1982 to 2005.In the SST nudging experiment,the model can reproduce the observed equatorial thermocline anomalies and zonal wind stress anomalies in the Pacific,which demonstrates that the SST nudging approach can provide realistic atmospheric and oceanic initial conditions for seasonal prediction experiments.The model also demonstrates a high Anomaly Correlation Coefficient (ACC) score for SST in most of the tropical Pacific,Atlantic Ocean,and some Indian Ocean regions with a 3-month lead.Compared with the persistence ACC score,this model shows much higher ACC scores for the Ni o-3.4 index for a 9-month lead.
基金supported by the National Natural Science Foundation of China (NSFC 50809068)the foundation of the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,China (10502)+1 种基金the China Postdoctoral Science Foundation (20080441196)the West Light Foundation of the Chinese Academy of Science
文摘Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol （Cinnamon soil）, with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence （F0） of leaves was higher in the dry treatment （0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity） compared to the wet treatment （entire soil column at 75-80% of field capacity）. The maximal fluorescence （Fm）, the variable fluorescence （Fv）, the photochemical efficiency （Fv/Fm） and potential activites （Fv/F0） of photosystem 2 （PS2） were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased FJFm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 em of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and F,fFm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants FJFm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.
基金the NKBRSF Project! G 1999043400 the CNSF Project! 49735180.
文摘Two land surface schemes, one the standard Biosphere / Atmosphere Transfer Scheme Version ie (BOZ) and the other B1Z based on B0Z and heterogeneously-treated by' combined approach' , were co 'pled to the meso-scale model MM4, respectively. Through the calculations of equations from the companion paper, parameters representing land surface heterogeneity and suitable for the coupling models were found out. Three cases were simulated for heavy rainfalls during 36 hours, and the sensitivity of short-term weather modeling to the land surface heterogeneity was tested. Through the analysis of the simulations of the three heavy rainfalls, it was demonstrated that BIZ, compared with BOZ, could more realistically reflect the features of the land surface heterogeneity, therefore could more realistically reproduce the circulation and precipitation amount in the heavy rainfall processes of the three cases. This shows that even short-term weather is sensitive to the land surface heterogeneity, which is more obvious with time passing, and whose influence is more pronounced in the lower layer and gradually extends to the middle and upper layer. Through the analysis of these simulations with BlZ, it is suggested that the bulk effect of smaller-scale fluxes (i.e., the momentum, water vapor and sensible heat fluxes) near the s ig nificantly-heterogeneous land surface is to change the larger-scale (i.e., meso-scale) circulation, and then to influence the development of the low-level jets and precipitation. And also, the complexity of the land-atmosphere interaction was shown in these simulations.
基金financially supported by the National Basic Research Program of China(973 ProgramGrant Nos.2014CB046801 and 2014CB046805)
文摘The floating foundation is designed to support a 1.5 MW wind turbine in 30 m water depth. With consideration of the viscous damping of foundation and heave plates, the amplitude-frequency response characteristics of the foundation are studied. By taking into account the elastic effect of blades and tower, the classic quasi-steady blade-element/momentum（BEM） theory is used to calculate the aerodynamic elastic loads. A coupled dynamic model of the turbine-foundationmooring lines is established to calculate the motion response of floating foundation under Kaimal wind spectrum and regular wave by using the FAST codes. The model experiment is carried out to test damping characteristics and natural motion behaviors of the wind turbine system. The dynamics response is tested by considering only waves and the joint action of wind and waves. It is shown that the wind turbine system can avoid resonances under the action of wind and waves. In addition, the heave motion of the floating foundation is induced by waves and the surge motion is induced by wind. The action of wind and waves is of significance for pitch.
基金Project supported by the National High-Tech Research and Development Program of China
文摘The effects of toughener and coupling agent on special epoxy silicone adhesive were discussed by researching the surface morphology characters, thermal properties and shear strength of the adhesive. The results indicate that silicone coupling agent (KH-550) can improve the shear strength of the epoxy silicone adhesive effectively. The mass fraction of the toughener in the epoxy silicone adhesive plays an important role in its properties. When the mass fraction of the toughener is less than 14%, the shear strength of the adhesive is low. When the mass fraction of the toughener is over 33%, thermal properties and shear strength of the adhesive decrease with the increasing of the toughener. The mass fraction of toughener of 25% results in good integral properties of the epoxy silicone adhesive. The morphologic analysis indicates that the micro-phase separation exists in the epoxy molecular chain and the silicone molecular chain of the epoxy silicone adhesive.
基金supported by the National Natural Science Foundation of China(10772112 and 10472065)the Key Project of Ministry of Education of China(107043)+2 种基金the Key Scientific Project of Shanghai Municipal Education Commission(09ZZ 17)the Specialized Research Fund for the Doctoral Program of Higher Education of China(20070248032)the Research Project of State Key Laboratory of Ocean Engineering of China(GKZD010807)
文摘The first-order approximation coupling （FOAC） model was proposed recently for dynamics and control of flexible hub-beam systems. This model may deal with system dynamics for both low and high rotation speed, while the classical zeroth-order approximation coupling （ZOAC） model is only available for low rotation speed. This paper assumes the FOAC model to present experimental study of active positioning control of a flexible hub-beam system. Linearization and nonlinear control strategies are both considered. An experiment system based on a DSP TMS320F2812 board is introduced. The difference between linearization and nonlinear control strategies are studied both numerically and experimentally. Simulation and experimental results indicate that, linearized controller can make the system reach an expected position with suppressed vibration of flexible beam, but the time taken to position is longer than expected, whereas nonlinear controller works well with precise positioning, suppression of vibration and time control.
文摘By using the experimental approach of dropping liquid, the coupling of three anionic wetting agents with ten dust samples of sulfide ores was studied, and particularly the wetting effects of the wetting agents on the sulfide dust influenced by factors of agent concentration and sulfate additive in the wetting agent solutions were investigated. The results show that when the solution temperature is about 20 ℃, all the selected wetting agents are effective to most dust samples, but the effect is different. Wetting agents are more effective to the dust which is difficult to be wetted. Wetting agent solution with sodium sulfate can improve the wetting ability of sulfide dust. For sodium dodecyl benzene sulfonate, the suitable concentration of sodium sulfate is 12 mmol/L. The cost of wetting agents can be reduced because the sodium sulfate is much cheaper than many surfactants. Since the dust of sulfide ores is composed of various minerals and elements, the whole effect of depressing dust should be considered while innovating a wetting agent.
基金National Science Foundation of China (No.50974059No.50934006)
文摘This paper puts forward a new rock fragmentation loading method of dual-cutter head combined dynamic and static loads. By applying the numerical simulation software - RFPA2D, we have done numerical experiment about the sihstone＇ s crushing effect by dynamic load on single cutter head without confining pressure, dynamic load on single cut- ter head with confining pressure 10 MPa and different dual-cutter heads spacing by combined dynamic and static loads with confining pressure 10 MPa. Experimental results show that the confining pressure can obviously affect the rock frag- mentation effect. Combined dynamic and static loads can greatly improve the rock fragmentation effect. There exists an optimal spacing of dual-cutter head that can make the rock fragmentation achieve the desired effect. Through analyzing the acoustic emission accumulative energy and quantity, the authors make a conclusion that the optimum spacing is 30 mm.
基金Supported by the National Natural Science Foundation of China(Nos. 50534030,50490274)the National Key Basic Research Plan of China(No. 2002CB412703)the Innovation Project of Central South University in China
文摘Experiments of silt rock subjected to coupling loads were carried out on tailormade equipment. With a constant dynamic load, the behaviors of eight sets of siltite specimens were investigated with different axial static loads. The experimental results show that the modulus of the specimens under coupling loads increases at first and then decreases with the increase of axial static pressure. The failure model of the specimens also varies. Keeping the dynamic load constant, when the axial static pressure is low, the specimen breaks in two simply. With the increase of axial static pressure, the cone-shaped fragment appeares. When the axial static pressure reaches 90% of the static strength of rock, the specimen smashes into amount of small fragments.
文摘The research on structural vibration and sound radiation of underwater ring-ribbed cylindrical shell,which is coated with a kind of deadening and decoupling materials,becomes a focus in recent years.This paper analyzes the problem on two aspects:model experiment and numerical calculation.The model experiment is carried out including three cases firstly,in which the structural vibration response and radiating acoustic field are measured respectively,and the results gained in these three cases are analyzed to discuss the effect of reducing structural vibration and radiating noise of the deadening and decoupling materials.The coupling FEM/BEM and the SEA methods are both used in numerical calculation,i.e.the arithmetic of the coupling FEM/BEM method is adopted to calculate the low frequency characteristics and the SEA method is adopted to calculate the medium-high frequencies characteristics of the model.By comparing experimental results with numerical calculation results,it is proved that the algorithm adopted in this paper is reasonable.
基金financially supported by the National Natural Science Foundation of China(Grant No.52265029)National Modern Agricultural Industrial Technology System Project(Grant No.CARS-09-P32)Hainan Postgraduate Innovation Project in 2024(Grant No.Qhyb2024-20).
文摘To address issues such as suboptimal separation of potatoes from soil during harvest,weak damage prevention and reduction capabilities in the transport process,and high damage rates,a potato-soil-transport device motion model was proposed based on potato farming practices in northern China(Gansu).The mechanical properties of the separation and transport device and the movement mechanism of the potatoes were analyzed,identifying key factors affecting the separation efficiency of potatoes from soil and potato damage:separation transport device inclination angle(ɑ),machine forward speed(V_(m)),paddle wheel amplitude(A),and paddle wheel frequency(ƒ).A coupled RecurDyn-EDEM simulation model was constructed to determine the impact of key factors on soil separation efficiency and potato damage.Using an optimization method,the optimal parameter combination for evaluating potato-soil separation was determined:separation transport device inclination angle of 18°,machine forward speed of 4.7 km/h,paddle wheel amplitude of 32.8 mm,and paddle wheel frequency of 6.0 Hz.Field tests showed that the potato-soil separation efficiency was good,with potatoes containing minimal soil and other impurities and experiencing minimal damage.The average potato-soil separation efficiency was 96%,and the average potato damage rate was 2%.Compared to the simulation results,the errors were 0.47%and 0.3%,respectively,meeting the quality requirements for potato harvesting operations.
