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low velocity Impact Response on GFRP and GF-SMP Panels in Structural and High Frequency Bands

Advances in Aerospace Science and Technology 2020年第2期5卷 58-70页

作者： R. Basavanna S. Raja Karisiddappa Civil Engineering Department Visvesvaraya Technological University Belagavi India Structural Technological Division CSIR-National Aerospace Laboratories Bangalore India Visvesvaraya Technological University Belagavi India

A low velocity impact response study has been carried out on glass fibre composite laminates, made up of regular aircraft grade epoxy (GFRP) and shape memory polymer (GF-SMP). Under various impact loading intensities (4J, 6J, 12J), the responses are measured by a network of PZT (Lead Zirconate Titanate) sensors. A signal analysis methodology is subsequently developed to process the very high frequency (60 MHz) sampled data. In two frequency bands, namely 0 - 2000 Hz and 0 - 100 KHz, the results are examined and the transient dynamic behaviours of the composite laminates are evaluated. It is observed that both the laminates have generated the high frequency structural waves (0 - 100 KHz), which can be exploited to examine the BVID. However, GF-SMP laminate has shown some advantage in terms of energy dissipation in the structural frequency band (<2000 Hz). Further, the GF-SMP laminate has demonstrated its capability to generate very high frequency structural waves, which could carry the damage information like BVID due to impact event to nearby sensors for impact event monitoring and health assessment.

关键词： Impact low velocity PZT Patches GFRP Composite Laminate Transient Dynamics

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low-velocity resistance distortion and bionic drag reduction for ship-type paddy field machinery

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International Journal of Agricultural and Biological Engineering 2020年第2期13卷 7-14页

作者： Guoqi Yan Peng Tian Jiasi Mo Heng Xie Huiling Wei College of Engineering South China Agricultural UniversityGuangzhou510642China College of Mechanical and Electrical Engineering Foshan UniversityFoshan 528000China

The resistance between mud surface and ship-type paddy field machine hull accounts for a certain proportion of the total mechanical power consumption during the operation *** special characteristic has been found via preliminary study,it showed that when starting or working at low velocity,the resistance is much greater than the machine working at the rated *** characteristic affects the dynamic matching and structural design of the *** critical velocity of resistance distortion was around 0.025 m/s under the setting experimental conditions,and the mechanism of resistance distortion under multi-medium was *** on water film drag reduction theory,a macroscopic structure of crocodile's abdominal armor biomimetic drag reduction method was *** kinds of bionic macroscopic structure ship board were *** macroscopic structure can introduce more water into the bottom surface of the hull;thicken the water film,which can reduce the travel *** and manufacture a ship-type paddy field experimental setup with velocity control,and compare the traditional smooth surface ship board with the two bionic macroscopic structure surfaces through orthogonal *** experiment results demonstrated that the ship board with rectangle gully structure has better drag reduction effect than the hexagon one in the lower *** when the travel velocity approach to the resistance distortion critical point,the hexagon gully structure become better than the other *** the orthogonal test,the best drag reduction combination is 2.5 kg load weight,0.025 m/s travel velocity with hexagon ship board,which decreases the drag by 6.3%.

关键词： ship-type paddy field machinery low velocity resistance distortion bionic drag reduction crocodile

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Origin of a giant fuzzy reflection zone and its implication for natural gas exploration in the southwestern Qiongdongnan Basin of the South China Sea

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Journal of Oceanology and Limnology 2023年第2期41卷 710-728页

作者： Junhui YU Pin YAN Yanlin WANG Yan QIU Guanghong TU Changliang CHEN Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyInnovation Academy of South China Sea Ecology and Environmental EngineeringChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of SciencesQingdao 266071China Key Laboratory of Marine Mineral Resources Guangzhou Marine Geological SurveyChina Geological SurveyMinistry of Natural ResourcesGuangzhou 511458China University of Chinese Academy of Sciences Beijing 100049China

The southwestern depression of the Qiongdongnan Basin(QDNB)hosts thick Cenozoic sediments and awaits major hydrocarbon *** seismic(MCS)profile CFT2011 across the southwestern QDNB reveals a~60-km-wide fuzzy reflection zone(FRZ)within the sediments,but its origin and distribution remain *** ocean bottom seismometer(OBS)data of Line CFT2011 are processed with focus on the velocity structures by traveltime tomography inversion and analyzed together with the coincident and adjacent MCS *** OBS velocity results show that the giant FRZ features lower velocity with difference up to 1.5 km/s and smaller vertical velocity gradient than the surrounding sedimentary sequences at the same depth,likely resulting from enhanced fluid *** MCS profile exhibits that the giant FRZ is about 3-9-km thick and extends from the Paleogene strata rich in organic matters upward to the lower Pleistocene *** the shallow overlying sediments,multiple bright spots with reverse polarity are imaged and their reflection amplitudes increase with offset,consistent with the features of gas-charged *** are probably shallow gas reservoirs with gases sourced from the deep ***,the FRZ is proposed to be a giant gas-charged zone,which probably contains lots of hydrocarbon gases migrated vertically from the deep Paleogene source rocks through the boundary faults of the depressions and the minor fractures generated under *** FRZ is also imaged on the adjacent MCS profiles MCS-L1 and MCS-L2 with the width of about 40 km and 68 km,*** is roughly estimated to cover an area of~1900 km2 and host a volume of~11400 km3 assuming an average thickness of 6 km,implying huge natural gas potential in the sedimentary depression of the southwestern QDNB of the South China Sea.

关键词： southwestern Qiongdongnan Basin fuzzy reflection zone low velocity gas charging natural gas potential

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