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Your search keyword '"Yu, Zhe-Feng"' showing total 23 results
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23 results on '"Yu, Zhe-Feng"'

4. Blackout Mitigation by External Electromagnetic Field in Re-entry Vehicles

Author

Yu zhe feng, Yang ying, and Dong Weizhong

Subjects
Electromagnetic field, Physics, Debye sheath, Acoustics, Blackout, 01 natural sciences, Electromagnetic radiation, Magnetic field, symbols.namesake, Magnet, 0103 physical sciences, symbols, medicine, medicine.symptom, Antenna (radio), 010306 general physics, Voltage
Abstract

In order to solve the re-entry blackout problem, based on the former research on magnetic window antenna, the influence of external electromagnetic control on improving propagation of electromagnetic wave in plasma sheath is investigated. The magnet is NdFeB, and the applied voltage is 100V. Numerical simulation of the flow fields without electromagnetic field, with magnetic field, with electromagnetic field are conducted by using flow field data of different flight altitude. Based on the simulation result, comparison of electronic density and energy attenuation near the antenna window with different parameters shows that it is better to improve electromagnetic propagation in plasma sheath by electromagnetic window antenna than magnetic window antenna. With proper working condition of electromagnetic window antenna and appropriate parameters setting, the mitigation of blackout phenomena is obvious.

Published
2019

5. Simulation of graded bandgap on backwall superstrate CIGS solar cells with MoOx electron reflection layer

Author

Qi Shen, Xiao-Dong Feng, Jia-Ming Liu, Zhen-Qi Li, Ming Ni, and Yu-Zhe Feng

Subjects
Materials science, Polymers and Plastics, Bandgap grading, Band gap, business.industry, Metals and Alloys, Electron, Copper indium gallium selenide solar cells, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Biomaterials, Reflection (mathematics), Optoelectronics, business, Layer (electronics)
Published
2019

18. Design of two-dimensional plate directional heat transmission structure based on meta materials

Author

Yu Zhe-Feng, Huang Jie, and Sun Liang-Kui

Subjects
Materials science, Heat transmission, General Physics and Astronomy, Metamaterial, Mechanical engineering, Structure based
Abstract

Based on the transformation thermodynamics, the thermal conductivity expression for the unit cell of the directional heat transmission structure is derived by the oblique and rotary coordinate transformation. We obtain the two-dimensional plate directional heat transmission structure through periodically arranging the unit cells which are realized by layering copper and thermal insulation materials. The results from the numerical calculation indicate that the heat flux flows from the upper surface of the directional heat transmission structure to the two sides, while the upper and lower surface remain at low temperature. Compared with the temperature of SiO2 aerogel thermal insulation material, the upper surface temperature falls 33.3%, the low surface temperature falls 4.3%, while the temperatures of the two sides rise 40.1%. The decrease of the upper surface temperature indicates that the heat on the upper surface can be guided timely, and then the infrared radiation can be weakened. The decrease of the lower surface temperature indicates that the adiabatic efficiency of the directional heat transmission structure is superior to that of the SiO2 aerogel thermal insulation material. The heat transmission from the upper surface to the sides is conducive to the good use of the heat flux. The directional heat transmission has a potential application in the infrared stealth and heat protection.

Published
2015

23. Research on the RCS Characteristics of Hypersonic Near Space Vehicle.

Author

YU Zhe-feng, LIU Jia-qi, LIU Lian-yuan, REN Ai-min, LIANG Shi-chang, CHEN Xu-ming, WU Run-hui, and HUANG Jie

Subjects
*RADAR cross sections, *HYPERSONIC aerodynamics, *SPACE vehicles, *PLASMA sheaths, *TURBULENCE
Abstract

When a near space hypersonic vehicle (NHV) reenters the atmosphere, its scattering characteristics would be significantly changed by the formation of plasma sheath and wake. In this paper, the scattering characteristics of typical hypersonic near space vehicle are studied. Main contents included the RCS simulating of hypersonic vehicle surrounded by plasma sheath, underdense turbulent wake and laminar wake. The results show that the RCS of hypersonic near space vehicle would be decreased by plasma sheath in the back scattering direction. The RCS of hypersonic near space vehicle would be increased by the underdense turbulent wake at low frequency. But with the increase of radar frequency, the effect of underdense turbulent wake would be unobvious. Finally, Low frequency radar and bistatic radar are suggested to detect hypersonic near space vehicle. [ABSTRACT FROM AUTHOR]

Published
2014
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