In order to design the scale model in a wide frequency range,a method based on the reflective loss is proposed according to the high-frequency approximation algorithm,and an example of designing the scale model of a p...In order to design the scale model in a wide frequency range,a method based on the reflective loss is proposed according to the high-frequency approximation algorithm,and an example of designing the scale model of a plate-shaped absorber is given in this paper.In the example,the frequency of the full-size measurement ranges from 2.0 GHz to 2.4 GHz,the thickness of the full-size absorber is 1 mm and the scale ratio is 1/5.A two-layer scale absorber is obtained by the proposed method.The thickness values of the bottom and top layer are 0.4 mm and 0.5 mm,respectively.Furthermore,the scattering properties of a plate model and an SLICY model are studied by FEKO to verify the effectiveness of the designed scale absorber.Compared with the corresponding values from the theoretical scale model,the average values of the absolute deviations in 10 GHz～12 GHz are 0.53 d Bm^2,0.65 d Bm^2,0.76 d Bm^2 for the plate model and 0.20 d Bm^2,0.95 d Bm^2,0.77 d Bm^2 for the SLICY model while the incident angles are 0°,30°,and 60°,respectively.These deviations fall within the Radar cross section（RCS） measurement tolerance.Thus,the work in this paper has important theoretical and practical significance.展开更多
Aerodynamics of circular plate- and circular ring-shaped squeeze film hearings is analyzed in detail, yielding analytic expressions for the pressure distribution of these hearings. Several formulae for these hearings ...Aerodynamics of circular plate- and circular ring-shaped squeeze film hearings is analyzed in detail, yielding analytic expressions for the pressure distribution of these hearings. Several formulae for these hearings are modified using the developed method. The paper also gives numerical results oj pressure distribution and load-hearing capacities of these hearings.展开更多
Migration of He atoms and growth of He bubbles in high angle twist grain boundaries(HAGBs)in tungsten(W)are investigated by atomic simulation method.The energy and free volume(FV)of grain boundary(GB)are affected by t...Migration of He atoms and growth of He bubbles in high angle twist grain boundaries(HAGBs)in tungsten(W)are investigated by atomic simulation method.The energy and free volume(FV)of grain boundary(GB)are affected by the density and structure of dislocation patterns in GB.The migration energy of the He atom between the neighboring trapping sites depends on free volume along the migration path at grain boundary.The region of grain boundary around the He bubble forms an ordered crystal structure when He bubble grows at certain grain boundaries.The He atoms aggregate on the grain boundary plane to form a plate-shape configuration.Furthermore,high grain boundary energy(GBE)results in a large volume of He bubble.Thus,the nucleation and growth of He bubbles in twist grain boundaries depend on the energy of grain boundary,the dislocation patterns and the free volume related migration path on the grain boundary plane.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61601299 and 11404213)the Shanghai Municipal Science and Technology Commission,China(Grant Nos.17210730900 and 15ZR1439600)the Defense Industrial Technology,China(Grant No.B2120132001)
文摘In order to design the scale model in a wide frequency range,a method based on the reflective loss is proposed according to the high-frequency approximation algorithm,and an example of designing the scale model of a plate-shaped absorber is given in this paper.In the example,the frequency of the full-size measurement ranges from 2.0 GHz to 2.4 GHz,the thickness of the full-size absorber is 1 mm and the scale ratio is 1/5.A two-layer scale absorber is obtained by the proposed method.The thickness values of the bottom and top layer are 0.4 mm and 0.5 mm,respectively.Furthermore,the scattering properties of a plate model and an SLICY model are studied by FEKO to verify the effectiveness of the designed scale absorber.Compared with the corresponding values from the theoretical scale model,the average values of the absolute deviations in 10 GHz～12 GHz are 0.53 d Bm^2,0.65 d Bm^2,0.76 d Bm^2 for the plate model and 0.20 d Bm^2,0.95 d Bm^2,0.77 d Bm^2 for the SLICY model while the incident angles are 0°,30°,and 60°,respectively.These deviations fall within the Radar cross section（RCS） measurement tolerance.Thus,the work in this paper has important theoretical and practical significance.
文摘Aerodynamics of circular plate- and circular ring-shaped squeeze film hearings is analyzed in detail, yielding analytic expressions for the pressure distribution of these hearings. Several formulae for these hearings are modified using the developed method. The paper also gives numerical results oj pressure distribution and load-hearing capacities of these hearings.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11305136,11675230,11375242,and U1832112)
文摘Migration of He atoms and growth of He bubbles in high angle twist grain boundaries(HAGBs)in tungsten(W)are investigated by atomic simulation method.The energy and free volume(FV)of grain boundary(GB)are affected by the density and structure of dislocation patterns in GB.The migration energy of the He atom between the neighboring trapping sites depends on free volume along the migration path at grain boundary.The region of grain boundary around the He bubble forms an ordered crystal structure when He bubble grows at certain grain boundaries.The He atoms aggregate on the grain boundary plane to form a plate-shape configuration.Furthermore,high grain boundary energy(GBE)results in a large volume of He bubble.Thus,the nucleation and growth of He bubbles in twist grain boundaries depend on the energy of grain boundary,the dislocation patterns and the free volume related migration path on the grain boundary plane.
