According to the test results of the physical and mechanical properties of similar materials in various quality mixture, a type of material with obvious tendency of rockburst was selected to produce a large-size model...According to the test results of the physical and mechanical properties of similar materials in various quality mixture, a type of material with obvious tendency of rockburst was selected to produce a large-size model to simulate rockburst phenomena in tunnels. The prototype model comes from a typical section of diversion tunnels in Jinping Hydropower Station in China. The simulation of excavating tunnels is carried out by opening a hole in the model after loading. The modeling results indicated that under the condition of normal stresses in the model boundaries the arch top, spandrel and side walls of the tunnel produced an obvious jump reaction of stress and strain and the acoustic emission counts of the surrounding rock also increased rapidly in a different time period after the "tunnel" excavation, showing the clear features of rockburst. The spalling, buckling and breaking occurred in the surrounding rock of model in conditions of over loading. It is concluded that the modeling tunnel segment in Jinping Hydropower Station is expected to form the tensile rockburst with the pattern of spalling, buckling and breaking.展开更多
The Common Land Model(CoLM) was coupled with the IAP Dynamic Global Vegetation Model(IAPDGVM), and the performance of this combined CoLMIAP model was evaluated. Offline simulations using both the original Common Land ...The Common Land Model(CoLM) was coupled with the IAP Dynamic Global Vegetation Model(IAPDGVM), and the performance of this combined CoLMIAP model was evaluated. Offline simulations using both the original Common Land Model(CoLM-LPJ) and CoLM-IAP were conducted. The CoLM-IAP coupled model showed a significant improvement over CoLMLPJ, as the deciduous tree distribution decreased over temperate and boreal regions, while the distribution of evergreen trees increased over the tropics. Some biases in CoLM-LPJ were preserved, including the overestimation of evergreen trees in tropical savanna, the underestimation of boreal evergreen trees, and the absence of boreal shrubs. However, most of these biases did not exist in a further coupled simulation of IAP-DGVM with the Community Land Model(CLM), for which the parameters of IAP-DGVM were optimized. This implies that further improvement is needed to deal with the differences between CoLM and CLM in parameterizations of landbased physical and biochemical processes.展开更多
Most implantation cases are implemented using implants selected from the available standard set, but in some cases, only those implants conforming to individual patient's skeletal morphology can serve the purpose....Most implantation cases are implemented using implants selected from the available standard set, but in some cases, only those implants conforming to individual patient's skeletal morphology can serve the purpose. This paper proposes a new approach to design and fabricate custom-made exact-fit medical implants. With a real surgical case as the example,technical design details are presented; and three algorithms are given respectively for segmentation based on object features, triangular mesh defragmentation and mesh cutting.展开更多
The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum mod...The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies.展开更多
The first component of a building implemented in a virtual prototype concerning the management of a building is a lighting system. It was applied in a study case. The interactive application allows the examination of ...The first component of a building implemented in a virtual prototype concerning the management of a building is a lighting system. It was applied in a study case. The interactive application allows the examination of the physical model, visualizing, for each element modeled in three-dimensions (3D) and linked to a database, the corresponding technical information concerned with the use of the material, calculated for different points in time during their life. The control of a lamp stock, the constant updating of lifetime information and the planning of periodical local inspections are attended on the prototype. This is an important mean of cooperation between collaborators involved in the building management.展开更多
The Loess Plateau has a typical semi-arid climate, and the area suffers from very harsh ecological environment, severe soil erosion and water runoff, and uneven distributed precipitation. Due to the relatively low hol...The Loess Plateau has a typical semi-arid climate, and the area suffers from very harsh ecological environment, severe soil erosion and water runoff, and uneven distributed precipitation. Due to the relatively low holding capacity, current rainwater-collecting and conservation facilities can only supplement a maximum of18 mm of water for crop production in each irrigation. In this study, mathematical models were constructed to identify the water requirement critical period of maize crop by evaluating response of each individual developmental stage to supplemental irrigation with harvested rainwater. In the transformed Jensen model, ETmin/Eta was used as the index of relative evapotranspiration. The use of relative yield and relative crop evapotranspiration was able to eliminate influences from unintended environmental factors. A BP neural network crop-water model for extreme water deficit condition was constructed using the index of relative evapotranspiration as the input and the index of relative yield as the output after iterative training and adjustment of weight values. Comparison of measured maize yields to those predicted by the two models confirmed that the BP neural network crop-water model is more accurate than the transformed Jensen model in predicting the sensitivity index to waterdeficit at various growth stages and maize yield when provided with supplemental irrigation with harvested rainwater.展开更多
By using the Lewis-Riesenfeld invariant theory, we have studied the dynamical and the geometric phases in a generalized time-dependent A-type Jaynes Cummings model. We lind that, compared with the dynamical phases, th...By using the Lewis-Riesenfeld invariant theory, we have studied the dynamical and the geometric phases in a generalized time-dependent A-type Jaynes Cummings model. We lind that, compared with the dynamical phases, the geometric phases in a cycle case are independent of the frequency of the photon field, the coupling coefficient between photons and atoms, and the atom transition frequency. It is pointed out that the geometric phases in a cycle ease can be measured under the case of a stronger time-dependent photon field and a stronger coupling photon-atom system. On the other hand, the geometric phases of the model may be measured in the composition of cold atoms.展开更多
In the framework of the STATIMON project, the complex research was done in which mathematical models of buildings' construction were created, defects identification method developed and also monitoring concept was co...In the framework of the STATIMON project, the complex research was done in which mathematical models of buildings' construction were created, defects identification method developed and also monitoring concept was composed according which automated monitoring system and software prototypes and structures were implemented. The strategic aim of the development of buildings' monitoring system was realized by mathematical and physical modelling of the faults (defects); analysis of characteristics sensitive to defects; selection of stability parameters and measurements; creation of automated system prototype; investigation of the methods applied for the monitoring system and diagnostics; development of software and separate elements of the system and approbation of the whole complex. Thorough evaluation of the technical state of the buildings numerical is executed using physical models and natural objects which support reliable state identification of the building and also helps to track changes.展开更多
Shoulder lines are the most important landform demarcations for geographical analysis,soil erosion modeling and land use planning in the Loess Plateau area of China.This paper proposes an automatic,effective and accur...Shoulder lines are the most important landform demarcations for geographical analysis,soil erosion modeling and land use planning in the Loess Plateau area of China.This paper proposes an automatic,effective and accurate method of determining loess shoulder line from DEMs by integrating a hydrological D8 algorithm and a snake model.The watershed boundary line is adopted as the initial contour which evolves to identify the exact position of loess shoulder-line by the guidance of an external force of snake model from DEMs.Experiments show that the method overcomes the difficulties in both threshold selection for edge detection and the disconnecting issues in former extraction approaches.The accuracy evaluation of shoulder-line maps from the two test sites of the loess plateau area show obvious improvements in the extraction.The average contour matching distance of the new method is 12.0 m on 5 m resolution DEM,and shows improvement in the accuracy and continuity.The comparisons of accuracy evaluations of the two test sites show that the snake model method performs better in the loess plain area than in the area with high gully density.展开更多
基金supported by National Natural Science Fundation of China (Grant No. 40772176)Key Program for Research Group of SKLGP (Grant No. SKLGP2009Z002)Research Fund for the Doctoral Program of Higher Education of China(Grant No. 20105122110008)
文摘According to the test results of the physical and mechanical properties of similar materials in various quality mixture, a type of material with obvious tendency of rockburst was selected to produce a large-size model to simulate rockburst phenomena in tunnels. The prototype model comes from a typical section of diversion tunnels in Jinping Hydropower Station in China. The simulation of excavating tunnels is carried out by opening a hole in the model after loading. The modeling results indicated that under the condition of normal stresses in the model boundaries the arch top, spandrel and side walls of the tunnel produced an obvious jump reaction of stress and strain and the acoustic emission counts of the surrounding rock also increased rapidly in a different time period after the "tunnel" excavation, showing the clear features of rockburst. The spalling, buckling and breaking occurred in the surrounding rock of model in conditions of over loading. It is concluded that the modeling tunnel segment in Jinping Hydropower Station is expected to form the tensile rockburst with the pattern of spalling, buckling and breaking.
基金supported by Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05110103)the National Basic Research Program of China (Grant No. 2010CB951801)
文摘The Common Land Model(CoLM) was coupled with the IAP Dynamic Global Vegetation Model(IAPDGVM), and the performance of this combined CoLMIAP model was evaluated. Offline simulations using both the original Common Land Model(CoLM-LPJ) and CoLM-IAP were conducted. The CoLM-IAP coupled model showed a significant improvement over CoLMLPJ, as the deciduous tree distribution decreased over temperate and boreal regions, while the distribution of evergreen trees increased over the tropics. Some biases in CoLM-LPJ were preserved, including the overestimation of evergreen trees in tropical savanna, the underestimation of boreal evergreen trees, and the absence of boreal shrubs. However, most of these biases did not exist in a further coupled simulation of IAP-DGVM with the Community Land Model(CLM), for which the parameters of IAP-DGVM were optimized. This implies that further improvement is needed to deal with the differences between CoLM and CLM in parameterizations of landbased physical and biochemical processes.
文摘Most implantation cases are implemented using implants selected from the available standard set, but in some cases, only those implants conforming to individual patient's skeletal morphology can serve the purpose. This paper proposes a new approach to design and fabricate custom-made exact-fit medical implants. With a real surgical case as the example,technical design details are presented; and three algorithms are given respectively for segmentation based on object features, triangular mesh defragmentation and mesh cutting.
基金Projects(50935002, 11002039) supported by the National Natural Science Foundation of ChinaProject(HIT.KLOF.2009062) supported by Key Laboratory Opening Funding of Aerospace Mechanism and Control Technology,Chinasupport by "111 Project" (Grant No.B07018)
文摘The dynamic equivalent continuum modeling method of the mast which is based on energy equivalency principle was investigated. And three kinds of mast dynamic model were established, which were equivalent continuum model, finite element model and simulation model, respectively. The mast frequencies and mode shapes were calculated by these models and compared with each other. The error between the equivalent continuum model and the finite element model is less than 5% when the mast length is longer. Dynamic responses of the mast with different lengths are tested, the mode frequencies and mode shapes are compared with finite element model. The mode shapes match well with each other, while the frequencies tested by experiments are lower than the results of the finite element model, which reflects the joints lower the mast stiffness. The nonlinear dynamic characteristics are presented in the dynamic responses of the mast under different excitation force levels. The joint nonlinearities in the deployable mast are identified as nonlinear hysteresis contributed by the coulomb friction which soften the mast stiffness and lower the mast frequencies.
文摘The first component of a building implemented in a virtual prototype concerning the management of a building is a lighting system. It was applied in a study case. The interactive application allows the examination of the physical model, visualizing, for each element modeled in three-dimensions (3D) and linked to a database, the corresponding technical information concerned with the use of the material, calculated for different points in time during their life. The control of a lamp stock, the constant updating of lifetime information and the planning of periodical local inspections are attended on the prototype. This is an important mean of cooperation between collaborators involved in the building management.
基金Supported by Inner Mongolia water conservancy"Twelfth five-year"Major Science and Technology Demonstration Project-scientific Support Project for New Water-saving Irrigation Area of Four ten Million mu in Inner Mongolia in China(20121036)the National Natural Science Foundation of China(No.51469026,2012MS0621)the Guided Reward Fund for Scientific and Technological Innovation,Inner Mongolia,China
文摘The Loess Plateau has a typical semi-arid climate, and the area suffers from very harsh ecological environment, severe soil erosion and water runoff, and uneven distributed precipitation. Due to the relatively low holding capacity, current rainwater-collecting and conservation facilities can only supplement a maximum of18 mm of water for crop production in each irrigation. In this study, mathematical models were constructed to identify the water requirement critical period of maize crop by evaluating response of each individual developmental stage to supplemental irrigation with harvested rainwater. In the transformed Jensen model, ETmin/Eta was used as the index of relative evapotranspiration. The use of relative yield and relative crop evapotranspiration was able to eliminate influences from unintended environmental factors. A BP neural network crop-water model for extreme water deficit condition was constructed using the index of relative evapotranspiration as the input and the index of relative yield as the output after iterative training and adjustment of weight values. Comparison of measured maize yields to those predicted by the two models confirmed that the BP neural network crop-water model is more accurate than the transformed Jensen model in predicting the sensitivity index to waterdeficit at various growth stages and maize yield when provided with supplemental irrigation with harvested rainwater.
基金supported by the Beijing NSF under Grant No.1072010supported by Scientific Creative Platform Foundation of Beijing Municipal Commission of Education under Grant No.PXM2008_ 014224_067420
文摘By using the Lewis-Riesenfeld invariant theory, we have studied the dynamical and the geometric phases in a generalized time-dependent A-type Jaynes Cummings model. We lind that, compared with the dynamical phases, the geometric phases in a cycle case are independent of the frequency of the photon field, the coupling coefficient between photons and atoms, and the atom transition frequency. It is pointed out that the geometric phases in a cycle ease can be measured under the case of a stronger time-dependent photon field and a stronger coupling photon-atom system. On the other hand, the geometric phases of the model may be measured in the composition of cold atoms.
文摘In the framework of the STATIMON project, the complex research was done in which mathematical models of buildings' construction were created, defects identification method developed and also monitoring concept was composed according which automated monitoring system and software prototypes and structures were implemented. The strategic aim of the development of buildings' monitoring system was realized by mathematical and physical modelling of the faults (defects); analysis of characteristics sensitive to defects; selection of stability parameters and measurements; creation of automated system prototype; investigation of the methods applied for the monitoring system and diagnostics; development of software and separate elements of the system and approbation of the whole complex. Thorough evaluation of the technical state of the buildings numerical is executed using physical models and natural objects which support reliable state identification of the building and also helps to track changes.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40930531, 41001294, 41301422)the Open Project Foundation of State Key Laboratory of Resources and Environmental Information System in China (Grant No. 2010KF0002SA)
文摘Shoulder lines are the most important landform demarcations for geographical analysis,soil erosion modeling and land use planning in the Loess Plateau area of China.This paper proposes an automatic,effective and accurate method of determining loess shoulder line from DEMs by integrating a hydrological D8 algorithm and a snake model.The watershed boundary line is adopted as the initial contour which evolves to identify the exact position of loess shoulder-line by the guidance of an external force of snake model from DEMs.Experiments show that the method overcomes the difficulties in both threshold selection for edge detection and the disconnecting issues in former extraction approaches.The accuracy evaluation of shoulder-line maps from the two test sites of the loess plateau area show obvious improvements in the extraction.The average contour matching distance of the new method is 12.0 m on 5 m resolution DEM,and shows improvement in the accuracy and continuity.The comparisons of accuracy evaluations of the two test sites show that the snake model method performs better in the loess plain area than in the area with high gully density.