To implement the multi-way phase shifting maintaining the compact size and simplicity in structure,the uniform reference line concept was proposed for the differential phase shifter.However,the performance in bandwidt...To implement the multi-way phase shifting maintaining the compact size and simplicity in structure,the uniform reference line concept was proposed for the differential phase shifter.However,the performance in bandwidth and phase range deteriorates with the additional requirements considered.To solve this problem,a quarter wavelength coupled line section loaded with open/short stubs is proposed as the basic element to implement the main line and also reference line.According to the theoretical analysis on this basic element,the loading stubs can be used to control the phase shift and also the phase slope of the basic element without affecting the amplitude property.With the predetermined parameters of the uniform reference line,only two parameters are required for the implementation of different differential phase shifts.This demonstrates the high simplicity of the proposed structure.For demonstration,an eight-way differential phase shifter operating at 3.5 GHz was implemented using the vertically installed planar structure.The prototype was further fabricated and measured.Good agreement between simulation and measurement can be observed.The implemented phase shifter can provide a wide range of phase shifting values from 45°to 315°with reference to the uniform reference line over a relative bandwidth of 62.3%.展开更多
This paper describes the characteristics of liquefied natural gas （LNG） carriers briefly. The LNG carrier includes power plant selection, vapor treatment, liquid cargo tank type, etc. Two parameters fuel substitutio...This paper describes the characteristics of liquefied natural gas （LNG） carriers briefly. The LNG carrier includes power plant selection, vapor treatment, liquid cargo tank type, etc. Two parameters fuel substitution rate and recovery of boil of gas （BOG） volume to energy efficiency design index （EEDI） formula are added, and EEDI formula of LNG carriers is established based on ship EEDI formula. Then, based on steam turbine propulsion device of LNG carriers, mathematical models of LNG carriers＇ reference line value are established in this paper. By verification, the EEDI formula of LNG carriers described in this paper can provide a reference for LNG carrier EEDI calculation and green shipbuilding.展开更多
Rectangular tiles can be laid on a ship's hull for protection, but the sides of the tiles must be adjusted so adjacent tiles will conform to the curvature of the hull.A method for laying tiles along a reference li...Rectangular tiles can be laid on a ship's hull for protection, but the sides of the tiles must be adjusted so adjacent tiles will conform to the curvature of the hull.A method for laying tiles along a reference line was proposed, and an allowable range of displacement for the four vertices of the tile was determined.Deformations of each tile on a specific reference line were then obtained.It was found that the least deformation was required when the tiles were laid parallel to a line with the least curvature.After calculating the mean curvature on the surface, the surface was divided into three layout areas.A set of discrete points following the least deformation of the principal curvatures was obtained.A NURBS interpolation curve was then plotted as the reference line for laying tiles.The optimum size of the tiles was obtained, given the allowable maximum deformation condition.This minimized the number of bolts and the amount of stuffing.A typical aft hull section was selected and divided into three layout areas based on the distribution of curvature.The optimum sizes of rectangular tiles were obtained for every layout area and they were then laid on the surface.In this way the layout of the rectangular tiles could be plotted.展开更多
Abstract We present a sample of quasars discovered in an area near the Galactic Anti-Center covering 150°≤l≤ 210° and ｜b｜ ≤ 30°, based on LAMOST Data Release 3 （DR3）. This sample contains 151 sp...Abstract We present a sample of quasars discovered in an area near the Galactic Anti-Center covering 150°≤l≤ 210° and ｜b｜ ≤ 30°, based on LAMOST Data Release 3 （DR3）. This sample contains 151 spectroscopically confirmed quasars. Among them 80 are newly discovered with LAMOST. All these quasars are very bright, with i magnitudes peaking around 17.5 mag. All the new quasars were discovered serendipitously from objects that were originally targeted with LAMOST as stars having bluer colors, except for a few candidates targeted as variable, young stellar objects. This bright quasar sample at low Galactic latitudes will help fill the gap in the spatial distribution of known quasars near the Galactic disk that are used to construct an astrometric reference frame for the purpose of accurate proper motion measurements that can be applied to, for example, Gala. They are also excellent tracers to probe the kinematics and chemistry of the interstellar medium in the Milky Way disk and halo via absorption line spectroscopy.展开更多
In order to consider the stress path dependency of soils,this paper decomposes any arbitrary stress path into several infinitesimal stress paths.Then the infinitesimal stress path is further transformed into the super...In order to consider the stress path dependency of soils,this paper decomposes any arbitrary stress path into several infinitesimal stress paths.Then the infinitesimal stress path is further transformed into the superposition of two parts,i.e..a constant stress ratio part and a constant mean stress part,which arc sufficiently close to the real stress path.T he plastic strain increments under the transformed paths arc determined separately,and then the plastic strain under any path is obtained.Based on the instantaneous loading line of normally consolidated soil,a reference state line is proposed to determine the overconsolidation ratio and creep time of soil.The overconsolidation ratio is introduced into the viscous How rule to obtain the viscous strain increment.The strcss-strain-timc relationship for triaxial compression condition is extended to 3D stress condition by the transformed stress method.The proposed model adopts only seven material parameters and each of them has a clear physical meaning.Comparisons with test results demonstrate that the model can not only reasonably predict the plastic strain under typical stress paths of excavation,but adequately capture the time-dependent behaviours of soils,including creep,stress relaxation and strain rate effect.展开更多
基金The work described in this paper was supported by the National Natural Science Foundation of China(No.62071503).
文摘To implement the multi-way phase shifting maintaining the compact size and simplicity in structure,the uniform reference line concept was proposed for the differential phase shifter.However,the performance in bandwidth and phase range deteriorates with the additional requirements considered.To solve this problem,a quarter wavelength coupled line section loaded with open/short stubs is proposed as the basic element to implement the main line and also reference line.According to the theoretical analysis on this basic element,the loading stubs can be used to control the phase shift and also the phase slope of the basic element without affecting the amplitude property.With the predetermined parameters of the uniform reference line,only two parameters are required for the implementation of different differential phase shifts.This demonstrates the high simplicity of the proposed structure.For demonstration,an eight-way differential phase shifter operating at 3.5 GHz was implemented using the vertically installed planar structure.The prototype was further fabricated and measured.Good agreement between simulation and measurement can be observed.The implemented phase shifter can provide a wide range of phase shifting values from 45°to 315°with reference to the uniform reference line over a relative bandwidth of 62.3%.
基金Foundation item： Supported by the National Special Fund for Agro-scientific Research in the Public Interest （No.201003024）, and the National Natural Science Foundation of China （No.51409042 No. 51209034）.
文摘This paper describes the characteristics of liquefied natural gas （LNG） carriers briefly. The LNG carrier includes power plant selection, vapor treatment, liquid cargo tank type, etc. Two parameters fuel substitution rate and recovery of boil of gas （BOG） volume to energy efficiency design index （EEDI） formula are added, and EEDI formula of LNG carriers is established based on ship EEDI formula. Then, based on steam turbine propulsion device of LNG carriers, mathematical models of LNG carriers＇ reference line value are established in this paper. By verification, the EEDI formula of LNG carriers described in this paper can provide a reference for LNG carrier EEDI calculation and green shipbuilding.
基金Supported by Technological Support Project of Equipment Pre-research under Grant No.62201080202
文摘Rectangular tiles can be laid on a ship's hull for protection, but the sides of the tiles must be adjusted so adjacent tiles will conform to the curvature of the hull.A method for laying tiles along a reference line was proposed, and an allowable range of displacement for the four vertices of the tile was determined.Deformations of each tile on a specific reference line were then obtained.It was found that the least deformation was required when the tiles were laid parallel to a line with the least curvature.After calculating the mean curvature on the surface, the surface was divided into three layout areas.A set of discrete points following the least deformation of the principal curvatures was obtained.A NURBS interpolation curve was then plotted as the reference line for laying tiles.The optimum size of the tiles was obtained, given the allowable maximum deformation condition.This minimized the number of bolts and the amount of stuffing.A typical aft hull section was selected and divided into three layout areas based on the distribution of curvature.The optimum sizes of rectangular tiles were obtained for every layout area and they were then laid on the surface.In this way the layout of the rectangular tiles could be plotted.
基金supported by the National Key Basic Research Program of China(2014CB845705)the National Natural Science Foundation of China(Grant Nos.11403038,11473001 and U1531244)+2 种基金The Guo Shou Jing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope,LAMOST) is a National Major Scientific Project built by the Chinese Academy of SciencesFunding for the project has been provided by the National Development and Reform CommissionLAMOST is operated and managed by National Astronomical Observatories,Chinese Academy of Sciences
文摘Abstract We present a sample of quasars discovered in an area near the Galactic Anti-Center covering 150°≤l≤ 210° and ｜b｜ ≤ 30°, based on LAMOST Data Release 3 （DR3）. This sample contains 151 spectroscopically confirmed quasars. Among them 80 are newly discovered with LAMOST. All these quasars are very bright, with i magnitudes peaking around 17.5 mag. All the new quasars were discovered serendipitously from objects that were originally targeted with LAMOST as stars having bluer colors, except for a few candidates targeted as variable, young stellar objects. This bright quasar sample at low Galactic latitudes will help fill the gap in the spatial distribution of known quasars near the Galactic disk that are used to construct an astrometric reference frame for the purpose of accurate proper motion measurements that can be applied to, for example, Gala. They are also excellent tracers to probe the kinematics and chemistry of the interstellar medium in the Milky Way disk and halo via absorption line spectroscopy.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1839201,51778026,51421005&51538001).
文摘In order to consider the stress path dependency of soils,this paper decomposes any arbitrary stress path into several infinitesimal stress paths.Then the infinitesimal stress path is further transformed into the superposition of two parts,i.e..a constant stress ratio part and a constant mean stress part,which arc sufficiently close to the real stress path.T he plastic strain increments under the transformed paths arc determined separately,and then the plastic strain under any path is obtained.Based on the instantaneous loading line of normally consolidated soil,a reference state line is proposed to determine the overconsolidation ratio and creep time of soil.The overconsolidation ratio is introduced into the viscous How rule to obtain the viscous strain increment.The strcss-strain-timc relationship for triaxial compression condition is extended to 3D stress condition by the transformed stress method.The proposed model adopts only seven material parameters and each of them has a clear physical meaning.Comparisons with test results demonstrate that the model can not only reasonably predict the plastic strain under typical stress paths of excavation,but adequately capture the time-dependent behaviours of soils,including creep,stress relaxation and strain rate effect.
