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Under-ice ambient noise in the Arctic Ocean: observations at the long-term ice station

Acta Oceanologica Sinica 2020年第9期39卷 125-132页

作者： Xiao Han Jingwei Yin Yanming Yang Hongtao Wen Longxiang Guo Acoustic Science and Technology Laboratory Harbin Engineering UniversityHarbin 150001China Key Laboratory of marine Information Acquisition and Security(Harbin Engineering University) Ministry of Industry and Information TechnologyHarbin 150001China College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001China Laboratory of Ocean Acoustic and Remote Sensing Third Institute of OceanographyMinistry of Natural ResourcesXiamen 361005China

Under-ice ambient noise in the Arctic Ocean is studied using the data recorded by autonomous hydrophones at the long-term ice station during the 9th Chinese National Arctic Research ***-frequency analysis of two 7-s-long ice-induced noise samples shows that both ice collision and ice breaking noise have many outliers in the time-domain(impulsive characteristic)and abundant frequency components in the *** collision noise lasts for several seconds while the duration of ice breaking noise is much shorter(i.e.,less than tens of milliseconds).Gaussian distribution and symmetric alpha stable(sαs)distribution are used in this paper to fit the impulsive under-ice *** sαs distribution can achieve better performance as it can track the heavy tails of impulsive noise while Gaussian distribution *** paper also analyzes the meteorological variables during the under-ice noise observation experiment and deduces that the impulsive ambient noise was caused by the combined force of high wind speed and increasing atmosphere temperature on the ice *** Pearson correlation coefficients between long-term power spectral density variations of under-ice ambient noise and meteorological variables are also studied in this paper.

关键词： long-term ice station under-ice ambient noise time-frequency analysis power spectral density variations meteorological variables

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A Major Shift in Japan’s defense Policy

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Beijing Review 2015年第41期58卷 32-32页

作者： Wang Peng the Air force Engineering University

The upper house of the National Diet of Japan-- the Japanese equivalent of the U.S. Congress-- enacted new security legislation on September 19 that will allow its military, referred to as the self-defense forces, to... 详细信息

关键词：日本防卫军事行动安全立法美国国会自卫队二战

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Experimental and numerical investigation of a self-supplementing dual-cavity plasma synthetic jet actuator

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Plasma Science and Technology 2023年第2期25卷 172-178页

作者：郑博睿张倩赵太飞宋国正陈全龙 School of Automation and Information Engineering Xi'an University of TechnologyXi'an 710048People's Republic of China Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi'an 710038People's Republic of China The Green Aerotechnics Research Institute of Chongqing Jiaotong University Chongqing 401120People's Republic of China

The primary issue regarding the plasma synthetic jet actuator(PSJA)is its performance attenuation at high *** solve this issue,a self-supplementing,dual-cavity,plasma synthetic jet actuator(SD-PSJA)is designed,and the static properties of the SD-PSJA are investigated through experiments and numerical *** pressure measurement shows that the SD-PSJA has two saturation frequencies(1200 Hz and 2100 Hz),and the experimental results show that both the saturation frequencies decrease as the volume of the bottom cavity of the SD-PSJA *** the size of the supplement hole increases,the first saturation frequency increases continuously,while the second saturation frequency shows a trend of first decreasing and then *** simulations show that the working process of the SD-PSJA is similar to that of the PSJA,but the volume of the cavity in the SD-PSJA is smaller than that of the PSJA;the SD-PSJA can supplement air to the top cavity through two holes,thus reducing the refresh time and effectively improving the jet intensity of the actuator at high frequencies.

关键词： plasma flow control plasma synthetic jet actuator pressure measurements numerical simulations

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Crushing Behaviors of Frac tai Hexagonal Tubular Structures: Experiments and Plastic Analysis

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Acta Mechanica Solida Sinica 2019年第6期32卷 713-724页

作者： Weiwei Li Bei Zhang Hualin Fan Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact PLA Army Engineering UniversityNanjing 210007China Department of Civil Engineering Nanyang Institute of TechnologyNanyang 473004China Research Institute for National defense Engineering of Academy of Military Science PLA Luoyang 471023China

Fractal tubular structures(FTSs)can greatly increase the anti-crushing and energy absorption capacity of the *** reveal this mechanism,fractal hexagonal tubes(FHTs)with self-similar fractal structure were designed and *** experiments were carried out to verify the crushing modes of structures with different scale *** with the single-cell structure,FHTs have much greater mean crushing force(MCF).According to the experiments and the numerical simulations,when the side length of the second-order hexagon is 0.3 times of the length of the first-order primary hexagon,the FTS has the greatest peak force(PF)and MCF as well as the most excellent energy-absorbing *** folding styles were revealed by the experiments and the numerical simulation when changing the scale factor,including the overall folding mode,the local foaling mode and the hybrid folding *** plastic models were built,which consistently predicted the MCF.

关键词： Fractal structure Crushing Energy absorption Plastic analysis

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