The 3-D velocity tomography image of the central-eastern part of Qilianshan is obtained by the joint inversion of 3-D velocity structure and focal parameters based on the S-P data of micro-earthquakes recorded by the ...The 3-D velocity tomography image of the central-eastern part of Qilianshan is obtained by the joint inversion of 3-D velocity structure and focal parameters based on the S-P data of micro-earthquakes recorded by the digital seismic network set up for a Sino-French cooperation program since 1996. The inversed velocity structure does primarily reflect some important features of the deep structure in the region and provide the scientific background for the further study of active tectonic structure and the calculation of earthquake parameters.展开更多
Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture beha...Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors （SIFs） were calculated by the modified virtual crack closure integral （MVCCI） method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.展开更多
Numerical analysis of three-dimensional sound propagation in soft-soft or soft-hard circular ducts with circumferential and axial modes of sound sources at the inlet has been carried out. In this paper , the numerical...Numerical analysis of three-dimensional sound propagation in soft-soft or soft-hard circular ducts with circumferential and axial modes of sound sources at the inlet has been carried out. In this paper , the numerical method and the samples are offered and the effects of circumferential and axial modes on numerical results are discussed in detail .展开更多
Public understanding of climate and climate change is of broad societal importance.However,misconceptions regarding reasons for the seasons abound amongst students,teachers,and the public,many of whom believe that sea...Public understanding of climate and climate change is of broad societal importance.However,misconceptions regarding reasons for the seasons abound amongst students,teachers,and the public,many of whom believe that seasonality is caused by large variations in Earth’s distance from the Sun.Misconceptions may be reinforced by textbook illustrations that exaggerate eccentricity or show an inclined view of Earth’s near-circular orbit.Textbook explanations that omit multiple factors influencing seasons,that do not mesh with students’experiences,or that are erroneous,hinder scientifically valid reasoning.Studies show that many teachers share their students’misconceptions,and even when they understand basic concepts,teachers may fail to appreciate the range of factors contributing to seasonal change,or their relative importance.We have therefore developed a learning resource using Google Earth,a virtual globe with other useful,weather-and climate-related visualizations.A classroom test of 27 undergraduates in a public research university showed that 15 improved their test scores after the Google Earth-based laboratory class,whereas 5 disimproved.Mean correct answers rose from 4.7/10 to 6/10,giving a paired t-test value of 0.21.After using Google Earth,students are helped to segue to a heliocentric view.展开更多
We propose a novel 3-dimensional hollow waveguide with a variable air core for widely tunable devices.We observed a wavelength shift of 1.8 nm in a hollow waveguide resonator with a displacement of 6μm in an air core.
English teaching in vocational schools is complex and challenging. The author integrated the language into students' real life and attached more importance to quality of life in language classroom. The author made...English teaching in vocational schools is complex and challenging. The author integrated the language into students' real life and attached more importance to quality of life in language classroom. The author made several innovative changes such as Exploratory Practice, 3-D mode, learner autonomy, performance evaluation and so on during the teaching course. She advocates promoting mutual understanding and common development of both teacher and students so that students can be competitive enough in the future and teachers can also acquire professional development.展开更多
Aiming at the interferometric inverse synthetic aperture radar （InlSAR） imaging in the presence of squint, we investigate the influence of squint on the InlSAR imaging. First, coupling of the squint additive phase a...Aiming at the interferometric inverse synthetic aperture radar （InlSAR） imaging in the presence of squint, we investigate the influence of squint on the InlSAR imaging. First, coupling of the squint additive phase and the target azimuth/altitude coordinates to be solved may make the solution more difficult. Second, the squint angle may lead to estimation error of the vertical coordinates and distortion of the ultimate image. Traditional InlSAR imaging algorithms can not solve the above two problems effectively, so we propose a new method which combines the nonlinear least square （NLS） and coordinates transform （CT） to estimate the target coordinates, and a three-dimensional （3-D） image consistent with the real target is obtained accordingly. Simulations show that the proposed method is effective for the squint-mode InlSAR imaging.展开更多
Hierarchical art was used to solve the mixed mode placement for three dimensional （3-D） integrated circuit design. The 3-D placement flow stream includes hierarchical clustering, hierarchical 3-D floorplanning, vert...Hierarchical art was used to solve the mixed mode placement for three dimensional （3-D） integrated circuit design. The 3-D placement flow stream includes hierarchical clustering, hierarchical 3-D floorplanning, vertical via mapping, and recursive two dimensional （2-D） global/detailed placement phases. With state-of-the-art clustering and de-clustering phases, the design complexity was reduced to enhance the placement algorithm efficiency and capacity. The 3-D floorplanning phase solved the layer assignment problem and controlled the number of vertical vias. The vertical via mapping transformed the 3-D placement problem to a set of 2-D placement sub-problems, which not only simplifies the original 3-D placement problem, but also generates the vertical via assignment solution for the routing phase. The design optimizes both the wire length and the thermal load in the floorplan and placement phases to improve the performance and reliability of 3-D integrate circuits. Experiments on IBM benchmarks show that the total wire length is reduced from 15% to 35% relative to 2-D placement with two to four stacked layers, with the number of vertical vias minimized to satisfy a pre-defined upper bound constraint. The maximum temperature is reduced by 16% with two-stage optimization on four stacked layers.展开更多
Flapping plates of typical fishlike tail shapes are simulated to investigate their locomotion performance using the multi-block Lattice Boltzmann Method （LBM） and Immersed Boundary （IB） method. Numerical results s...Flapping plates of typical fishlike tail shapes are simulated to investigate their locomotion performance using the multi-block Lattice Boltzmann Method （LBM） and Immersed Boundary （IB） method. Numerical results show that fishlike forked configurations have better locomotion performance compared with unforked plates. Based on our results, the caudal fin in carangi- form mode has greater thrust, and the lunate tail fin in thtmniform mode has higher efficiency. These findings are qualitatively con- sistent with biological observations of fish swimming. Analysis of wake topology shows that the wake of the forked plate consists of a chain of alternating reverse horseshoe-like vortical structures. These structures induce a backward jet and generate a positive thrust. Moreover, this backward jet has a more favorable direction compared with that behind an unforked plate.展开更多
基金National Natural Science Foundation of China (40074010) and Natural Science Foundation of Gansu Province(ZS981-A25-011).
文摘The 3-D velocity tomography image of the central-eastern part of Qilianshan is obtained by the joint inversion of 3-D velocity structure and focal parameters based on the S-P data of micro-earthquakes recorded by the digital seismic network set up for a Sino-French cooperation program since 1996. The inversed velocity structure does primarily reflect some important features of the deep structure in the region and provide the scientific background for the further study of active tectonic structure and the calculation of earthquake parameters.
文摘Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors （SIFs） were calculated by the modified virtual crack closure integral （MVCCI） method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.
基金The project is supported by National Natural Science Foundation of China and National Education Commission Foundaion of China
文摘Numerical analysis of three-dimensional sound propagation in soft-soft or soft-hard circular ducts with circumferential and axial modes of sound sources at the inlet has been carried out. In this paper , the numerical method and the samples are offered and the effects of circumferential and axial modes on numerical results are discussed in detail .
基金This work was supported by the National Science Foundation,Division of Undergraduate Education,through[grant number 1323419]by Google Geo Curriculum Awards to De Paor and Whitmeyer.
文摘Public understanding of climate and climate change is of broad societal importance.However,misconceptions regarding reasons for the seasons abound amongst students,teachers,and the public,many of whom believe that seasonality is caused by large variations in Earth’s distance from the Sun.Misconceptions may be reinforced by textbook illustrations that exaggerate eccentricity or show an inclined view of Earth’s near-circular orbit.Textbook explanations that omit multiple factors influencing seasons,that do not mesh with students’experiences,or that are erroneous,hinder scientifically valid reasoning.Studies show that many teachers share their students’misconceptions,and even when they understand basic concepts,teachers may fail to appreciate the range of factors contributing to seasonal change,or their relative importance.We have therefore developed a learning resource using Google Earth,a virtual globe with other useful,weather-and climate-related visualizations.A classroom test of 27 undergraduates in a public research university showed that 15 improved their test scores after the Google Earth-based laboratory class,whereas 5 disimproved.Mean correct answers rose from 4.7/10 to 6/10,giving a paired t-test value of 0.21.After using Google Earth,students are helped to segue to a heliocentric view.
文摘We propose a novel 3-dimensional hollow waveguide with a variable air core for widely tunable devices.We observed a wavelength shift of 1.8 nm in a hollow waveguide resonator with a displacement of 6μm in an air core.
文摘English teaching in vocational schools is complex and challenging. The author integrated the language into students' real life and attached more importance to quality of life in language classroom. The author made several innovative changes such as Exploratory Practice, 3-D mode, learner autonomy, performance evaluation and so on during the teaching course. She advocates promoting mutual understanding and common development of both teacher and students so that students can be competitive enough in the future and teachers can also acquire professional development.
基金supported by the China National Funds for Distinguished Young Scientists (Grant No.61025006)
文摘Aiming at the interferometric inverse synthetic aperture radar （InlSAR） imaging in the presence of squint, we investigate the influence of squint on the InlSAR imaging. First, coupling of the squint additive phase and the target azimuth/altitude coordinates to be solved may make the solution more difficult. Second, the squint angle may lead to estimation error of the vertical coordinates and distortion of the ultimate image. Traditional InlSAR imaging algorithms can not solve the above two problems effectively, so we propose a new method which combines the nonlinear least square （NLS） and coordinates transform （CT） to estimate the target coordinates, and a three-dimensional （3-D） image consistent with the real target is obtained accordingly. Simulations show that the proposed method is effective for the squint-mode InlSAR imaging.
基金Supported by the National Natural Science Foundation of China (Nos.60833004 and 60876026)the 3-D Floorplanning and Placement Project of the Intel Corporation
文摘Hierarchical art was used to solve the mixed mode placement for three dimensional （3-D） integrated circuit design. The 3-D placement flow stream includes hierarchical clustering, hierarchical 3-D floorplanning, vertical via mapping, and recursive two dimensional （2-D） global/detailed placement phases. With state-of-the-art clustering and de-clustering phases, the design complexity was reduced to enhance the placement algorithm efficiency and capacity. The 3-D floorplanning phase solved the layer assignment problem and controlled the number of vertical vias. The vertical via mapping transformed the 3-D placement problem to a set of 2-D placement sub-problems, which not only simplifies the original 3-D placement problem, but also generates the vertical via assignment solution for the routing phase. The design optimizes both the wire length and the thermal load in the floorplan and placement phases to improve the performance and reliability of 3-D integrate circuits. Experiments on IBM benchmarks show that the total wire length is reduced from 15% to 35% relative to 2-D placement with two to four stacked layers, with the number of vertical vias minimized to satisfy a pre-defined upper bound constraint. The maximum temperature is reduced by 16% with two-stage optimization on four stacked layers.
基金the National Natural Science Foundation of China (Grant No. 10832010)the Innovation Project of the Chinese Academy of Sciences (Grant No. KJCX2-YW-L05)the 111 Project (Grant No. B07033)
文摘Flapping plates of typical fishlike tail shapes are simulated to investigate their locomotion performance using the multi-block Lattice Boltzmann Method （LBM） and Immersed Boundary （IB） method. Numerical results show that fishlike forked configurations have better locomotion performance compared with unforked plates. Based on our results, the caudal fin in carangi- form mode has greater thrust, and the lunate tail fin in thtmniform mode has higher efficiency. These findings are qualitatively con- sistent with biological observations of fish swimming. Analysis of wake topology shows that the wake of the forked plate consists of a chain of alternating reverse horseshoe-like vortical structures. These structures induce a backward jet and generate a positive thrust. Moreover, this backward jet has a more favorable direction compared with that behind an unforked plate.
