National University of Defense Technology

About: National University of Defense Technology is a education organization based out in Changsha, China. It is known for research contribution in the topics: Computer science & Radar. The organization has 39430 authors who have published 40181 publications receiving 358979 citations. The organization is also known as: Guófáng Kēxuéjìshù Dàxué & NUDT.

Is ghost imaging intrinsically more powerful against scattering

Abstract: We demonstrated experimental comparison between ghost imaging and traditional non-correlated imaging under disturbance of scattering. Ghost imaging appears more robust. The quality of ghost imaging does not change much when the scattering is getting stronger, while that of traditional imaging declines dramatically. A concise model is developed to explain the superiority of ghost imaging. Due to its robustness against scattering, ghost imaging will be useful in harsh environment.

Analysis and experimental realization of locally resonant phononic plates carrying a periodic array of beam-like resonators

Abstract: We present theoretical examination and experimental demonstration of locally resonant (LR) phononic plates consisting of a periodic array of beam-like resonators attached to a thin homogeneous plate. Such phononic plates feature unique wave physics due to the coexistence of localized resonance and structural periodicity. We demonstrate that a low-frequency complete band gap for flexural plate waves can be created in the proposed structure owing to the interaction between the localized resonant modes of the beam-like resonators and the flexural wave modes of the host plate. We show that the location and width of the complete band gap can be dramatically tuned by changing the properties of the beam-like resonators. To understand the opening mechanism and evolution behaviour of the complete band gap, some approximate but explicit models are provided and discussed. We further perform experimental measurements of a specimen fabricated by an array of double-stacked aluminum beam-like resonators attached to a thin aluminum plate with 5 cm structure periodicity. The experimental results evidence a complete band gap extending from 465 to 860 Hz, matching well with our theoretical prediction. The LR phononic plates proposed in this work can find potential applications in attenuation of low-frequency mechanical vibrations and insulation of low-frequency audible sound.

Experimental Realization of H2/Air Continuous Rotating Detonation in a Cylindrical Combustor

Abstract: Results of experimental studies on a H2/air continuous rotating detonation engine (CRDE) in an annular combustor are presented. A tangentially injected H2/O2 hotshot jet is used to ignite the engine. H2/air continuous rotating detonations are realized at a wide range of total mass flow and equivalence ratio conditions. The detonation propagation modes of all the tests can be divided into four kinds: two-wave, hybrid two/one wave, one-wave, and transient one wave. The mean propagation velocities of the two-wave and one-wave modes are in the range 1365–1476 m/s and 1606–1791 m/s, respectively. The propagation mode and velocity are influenced by both the total mass flow rate and equivalence ratio. Detonation wave propagation processes of the two-wave and one-wave modes are also observed, which further demonstrates the realization of CRDE.