In order to provide accurate launching pitching angular velocity（LPAV） for the exterior trajectory optimization design, multi-flexible body dynamics（MFBD） technology is presented to study the changing law of LPAV ...In order to provide accurate launching pitching angular velocity（LPAV） for the exterior trajectory optimization design, multi-flexible body dynamics（MFBD） technology is presented to study the changing law of LPAV of the rotating missile based on spiral guideway. An MFBD virtual prototype model of the rotating missile launching system is built using multi-body dynamics modeling technology based on the built flexible body models of key components and the special force model.The built model is verified with the frequency spectrum analysis. With the flexible body contact theory and nonlinear theory of MFBD technology, the research is conducted on the influence of a series of factors on LPAV, such as launching angle change, clearance between launching canister and missile,thrust change, thrust eccentricity and mass eccentricity, etc. Through this research, some useful values of the key design parameters which are difficult to be measured in physical tests are obtained. Finally,a simplified mathematical model of the changing law of LPAV is presented through fitting virtual test results using the linear regression method and verified by physical flight tests. The research results have important significance for the exterior trajectory optimization design.展开更多
Based on a simplified domain rotation model, the rotation path of internal domains and cor- responding magnetostriction of <112>, <111> oriented single Tedenol-D crystals under com- pressive prestresses ha...Based on a simplified domain rotation model, the rotation path of internal domains and cor- responding magnetostriction of <112>, <111> oriented single Tedenol-D crystals under com- pressive prestresses have been simulated. Comparisons with results of experiment and other calculation have been made. Results of simulation showed that the <111> oriented single crystal has better low-field magnetostriction properties than the <112> oriented one. Under a compressive prestress of 10 MPa, up to 2300×10-6 saturation magnetostriction of <111> oriented crystal has been obtained at 800 Oe, while for <112> oriented. 1600×10-6 maximum magnetostriction has been reached at 1000 Oe.展开更多
In an extraction turbine, pressure of the extracted steam and rotate speed of the rotor are two important controlled quantities. The traditional linear state feedback control method is not perfect enough to control th...In an extraction turbine, pressure of the extracted steam and rotate speed of the rotor are two important controlled quantities. The traditional linear state feedback control method is not perfect enough to control the two quantities accurately because of existence of nonlinearity and coupling. A generalized minimum variance control method is studied for an extraction turbine. Firstly, a nonlinear mathematical model of the control system about the two quantities is transformed into a linear system with two white noises. Secondly, a generalized minimum variance control law is applied to the system. A comparative simulation is done. The simulation results indicate that precision and dynamic quality of the regulating system under the new control law are both better than those under the state feedback control law.展开更多
A multichannel methanoic acid （HCOOH, λ=432.5 μm） laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide （HCN, λ=337 μm） laser interferometer in the HL-2A tokamak....A multichannel methanoic acid （HCOOH, λ=432.5 μm） laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide （HCN, λ=337 μm） laser interferometer in the HL-2A tokamak. A conventional Michelson-type interometer is used for the electron density measurement, and a Dodel-Kunz-type polarimeter is used for the Faraday rotation effect measurement, respectively. Each HCOOH laser can produce a linearly polarized radiation at a power lever of -30 mW, and a power stability 〈10% in 50 rain. A beam waist （diameter d0 ≈12.0 mm, about 200 mm away from the outlet） is finally determined through a chopping modulation technique. The latest optical layout of the interferometer/polarimeter has been finished, and the hardware data processing system based on the fast Fourier transform phase- comparator technique is being explored. In order to demonstrate the feasibility of the diagnostic scheme, two associated bench simulation experiments were carried out in the laboratory, in which the plasma was simulated by a piece of polytetrafluoroethene plate, and the Faraday rotation effect was simulated by a rotating half-wave plate. Simulation results agreed well with the initial experimental conditions. At present, the HCOOH laser interferometer/polarimeter system is being assembled on HL-2A, and is planned to be applied in the 2014-2015 experimental campaign.展开更多
In this paper the authors present a derivation of a back-scatter rotational Large Eddy Simulation model,which is the extension of the Baldwin&Lomax model to nonequilibrium problems.The model is particularly design...In this paper the authors present a derivation of a back-scatter rotational Large Eddy Simulation model,which is the extension of the Baldwin&Lomax model to nonequilibrium problems.The model is particularly designed to mathematically describe a fluid filling a domain with solid walls and consequently the differential operators appearing in the smoothing terms are degenerate at the boundary.After the derivation of the model,the authors prove some of the mathematical properties coming from the weighted energy estimates,which allow to prove existence and uniqueness of a class of regular weak solutions.展开更多
Structural relaxation and glass transition in binary hard-spherical particle mixtures have been reported to exhibit unusual features depending on the size disparity and composition. However, the mechanism by which the...Structural relaxation and glass transition in binary hard-spherical particle mixtures have been reported to exhibit unusual features depending on the size disparity and composition. However, the mechanism by which the mixing effects lead to these features and whether these features are universal for particles with anisotropic geometries remains unclear. Here, we employ event-driven molecular dynamics simulation to investigate the dynamical and structural properties of binary two-dimensional hard-ellipse mixtures. We find that the relaxation dynamics for translational degrees of freedom exhibit equivalent trends as those observed in binary hard-spherical mixtures. However, the glass transition densities for translational and rotational degrees of freedom present different dependencies on size disparity and composition. Furthermore,we propose a mechanism based on structural properties that explain the observed mixing effects and decoupling behavior between translational and rotational motions in binary hard-ellipse systems.展开更多
基金supported by the Key Special Funds for National Defense Basic Scientific Research of China (No. C0320110005)
文摘In order to provide accurate launching pitching angular velocity（LPAV） for the exterior trajectory optimization design, multi-flexible body dynamics（MFBD） technology is presented to study the changing law of LPAV of the rotating missile based on spiral guideway. An MFBD virtual prototype model of the rotating missile launching system is built using multi-body dynamics modeling technology based on the built flexible body models of key components and the special force model.The built model is verified with the frequency spectrum analysis. With the flexible body contact theory and nonlinear theory of MFBD technology, the research is conducted on the influence of a series of factors on LPAV, such as launching angle change, clearance between launching canister and missile,thrust change, thrust eccentricity and mass eccentricity, etc. Through this research, some useful values of the key design parameters which are difficult to be measured in physical tests are obtained. Finally,a simplified mathematical model of the changing law of LPAV is presented through fitting virtual test results using the linear regression method and verified by physical flight tests. The research results have important significance for the exterior trajectory optimization design.
文摘Based on a simplified domain rotation model, the rotation path of internal domains and cor- responding magnetostriction of <112>, <111> oriented single Tedenol-D crystals under com- pressive prestresses have been simulated. Comparisons with results of experiment and other calculation have been made. Results of simulation showed that the <111> oriented single crystal has better low-field magnetostriction properties than the <112> oriented one. Under a compressive prestress of 10 MPa, up to 2300×10-6 saturation magnetostriction of <111> oriented crystal has been obtained at 800 Oe, while for <112> oriented. 1600×10-6 maximum magnetostriction has been reached at 1000 Oe.
文摘In an extraction turbine, pressure of the extracted steam and rotate speed of the rotor are two important controlled quantities. The traditional linear state feedback control method is not perfect enough to control the two quantities accurately because of existence of nonlinearity and coupling. A generalized minimum variance control method is studied for an extraction turbine. Firstly, a nonlinear mathematical model of the control system about the two quantities is transformed into a linear system with two white noises. Secondly, a generalized minimum variance control law is applied to the system. A comparative simulation is done. The simulation results indicate that precision and dynamic quality of the regulating system under the new control law are both better than those under the state feedback control law.
基金supported by the National Magnetic Confinement Fusion Science Programs of China(Nos.2010GB101002 and 2014GB109001)National Natural Science Foundation of China(Nos.11075048 and 11275059)
文摘A multichannel methanoic acid （HCOOH, λ=432.5 μm） laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide （HCN, λ=337 μm） laser interferometer in the HL-2A tokamak. A conventional Michelson-type interometer is used for the electron density measurement, and a Dodel-Kunz-type polarimeter is used for the Faraday rotation effect measurement, respectively. Each HCOOH laser can produce a linearly polarized radiation at a power lever of -30 mW, and a power stability 〈10% in 50 rain. A beam waist （diameter d0 ≈12.0 mm, about 200 mm away from the outlet） is finally determined through a chopping modulation technique. The latest optical layout of the interferometer/polarimeter has been finished, and the hardware data processing system based on the fast Fourier transform phase- comparator technique is being explored. In order to demonstrate the feasibility of the diagnostic scheme, two associated bench simulation experiments were carried out in the laboratory, in which the plasma was simulated by a piece of polytetrafluoroethene plate, and the Faraday rotation effect was simulated by a rotating half-wave plate. Simulation results agreed well with the initial experimental conditions. At present, the HCOOH laser interferometer/polarimeter system is being assembled on HL-2A, and is planned to be applied in the 2014-2015 experimental campaign.
基金supported by the group GNAMPA of INd AM and the University of Pisa,under grantPRA 201852 UNIPI。
文摘In this paper the authors present a derivation of a back-scatter rotational Large Eddy Simulation model,which is the extension of the Baldwin&Lomax model to nonequilibrium problems.The model is particularly designed to mathematically describe a fluid filling a domain with solid walls and consequently the differential operators appearing in the smoothing terms are degenerate at the boundary.After the derivation of the model,the authors prove some of the mathematical properties coming from the weighted energy estimates,which allow to prove existence and uniqueness of a class of regular weak solutions.
基金supported by the National Natural Science Foundation of China(21474109,21674055)the International Partnership Program of Chinese Academy of Sciences(121522KYSB20160015)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2016204)
文摘Structural relaxation and glass transition in binary hard-spherical particle mixtures have been reported to exhibit unusual features depending on the size disparity and composition. However, the mechanism by which the mixing effects lead to these features and whether these features are universal for particles with anisotropic geometries remains unclear. Here, we employ event-driven molecular dynamics simulation to investigate the dynamical and structural properties of binary two-dimensional hard-ellipse mixtures. We find that the relaxation dynamics for translational degrees of freedom exhibit equivalent trends as those observed in binary hard-spherical mixtures. However, the glass transition densities for translational and rotational degrees of freedom present different dependencies on size disparity and composition. Furthermore,we propose a mechanism based on structural properties that explain the observed mixing effects and decoupling behavior between translational and rotational motions in binary hard-ellipse systems.
