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| 1 | Study of ultra-wideband radar signals-generated technology using two-channel signal generator显示文摘Synthesis of ultra-wideband (UWB) linear frequency modulation radar signals is a very important technology for microwave imaging, target identification and detection of low radar-cross-section (RCS) targets. A new method of UWB radar signals generation with two-channel signal generator is presented. The realization structure is given; the principle and errors of signal synthesis are analyzed. At the same time, an automatic adjustment measure of signal phase is proposed because of phase discontinuity of waveform in this method. The simulation experiment and analysis results indicate that radar signals with large instantaneous bandwidth can be generated by means of this method on the condition that the high-speed digital devices are limited. | Wan Yonglun Lu Youxin Si Qiang Wang Xuegang Cao Guangping | 2007 | Journal of Systems Engineering and Electronics2007，18，4： | 4 |
| 2 | Review and Analysis of Key Techniques in Marine Sediment Sampling显示文摘Deep-sea sediment is extremely important in marine scientific research,such as that concerning marine geology and microbial communities.The research findings are closely related to the in-situ information of the sediment.One prerequisite for investigations of deep-sea sediment is providing sampling techniques capable of preventing distortion during recovery.As the fruit of such sampling techniques,samplers designed for obtaining sediment have become indispensable equipment,owing to their low cost,light weight,compactness,easy operation,and high adaptability to sea conditions.This paper introduces the research and application of typical deep-sea sediment samplers.Then,a representative sampler recently developed in China is analyzed.On this basis,a review and analysis is conducted regarding the key techniques of various deep-sea sediment samplers,including sealing,pressure and temperature retaining,low-disturbance sampling,and no-pressure drop transfer.Then,the shortcomings in the key techniques for deep-sea sediment sampling are identified.Finally,prospects for the future development of key techniques for deep-sea sediment sampling are proposed,from the perspectives of structural diversification,functional integration,intelligent operation,and high-fidelity samples.This paper summarizes the existing samplers in the context of the key techniques mentioned above,and can provide reference for the optimized design of samplers and development of key sampling techniques. | Shudong He Youduo Peng Yongping Jin Buyan Wan Guangping Liu | 2020 | Chinese Journal of Mechanical Engineering2020，33，5： | 2 |
| 3 | Design and Experimental Study of Pressure Compensation System for Full-Ocean-Depth Gas-Tight Sediment Sampler显示文摘Aiming at the requirement of the full-ocean-depth(operating water depth 11000 m)manned submersible to carry out the gas-tight sampling operation of the abyss seabed sediment,a kind of full-ocean-depth carrier submersible mechanical hand-held,full-ocean-depth gas-tight sediment sampler(GTSS)with the function of pressure-retaining and coring is designed.Firstly,the volume change model of pressure compensator is established,and it is pointed out that the volume of pressure compensator is about 16.14%equal to the volume of gas-tight sediment sampler(GTSS).Secondly,the pressure compensator is analyzed and calculated,and the relationship between the precharge pressure of the pressure compensator,the nominal volume of the pressure compensator and the pressure holding effect of the gas-tight sediment sampler(GTSS)is studied.The results show that with the increase of gas precharge pressure in the pressure compensator,the final pressure of the sampler also increases.Under the same precharge pressure condition,the larger the nominal volume of the pressure compensator,the greater the final pressure of the sampler.Finally,the air tightness test method is designed by using the developed gas tightness sampler of the full-ocean-depth product,and the change of the final pressure in the gas tight sampler under different precharge pressure is observed.The test results are consistent with the simulation results,indicating the correctness of the pressure compensation system(PCS)model. | Guangping Liu Yongping Jin Youduo Peng Buyan Wan | 2022 | Chinese Journal of Mechanical Engineering2022，35，2： | 1 |
| 4 | Inhibitory Activities on α-Glucosidase and Composition Analysis of Different Fractions of Ethanol Extracts from Actinidia chinensis Radix显示文摘Tlie inhibitory actions of ethyl acetate,n-butanol and water fractions from Actinidia chinensis Radix (A. chinensis Radix) ethanol extracts on glucosidase were investigated. We found that the inhibitory activity of different ethanol extract fractions on α-glucosidase is concentration-dependent. At the same concentration, the ethyl acetate and n-butaiiol fractions showed higher inliibitory activities on gglucosidase in comparison witli acarbose. We then determined the chemical constituents of tlie ethyl acetate and n-butanol fractions through ultra performance liquid cliromatography-triple-time of flight/mass spectrometry(UPLC-Triple-TOF/MS). Based on the mass spectrometry analysis and the databases Scitinder and Reaxys, 21 compoiinds(A1-A21) were identified from the ethyl acetate fraction. In addition, 11 of those compounds(A2, A3, A5, A6, A8, A10, A11, A13, A15, A19, A20) were identified for the first time from A. chinensis Radix. We also identified 14 compounds(A22-A32 and A4-A6) from tlie w-butanol fraction and compound A29 is a new natural product. From the n-butanol fraction, 7 additional compounds (A22, A25, A27, A28, A30-A32) were identified from A. chinensis Radix for the first time. | NIE Changping YANG Jun WU Dan WAN Luping LIANG Guangping | 2019 | Chemical Research in Chinese Universities2019，35，5： | 0 |
| 5 | Synthesis of SiO_2@SiO_2 core-shell microspheres using urea-formaldehyde polymers as the templates for fast separation of small solutes and proteins显示文摘Superficially porous core-shell silica microspheres(CSSMs) have been a great success for the fast separation of small molecules and proteins in recent years. In this paper, the CSSMs were synthesized by an improved polymerization-induced colloid aggregation(PICA) method using urea-formaldehyde polymers as the templates. The agglomeration of the functionalized silica core was avoided by the surface modification through reflux with ureidopropyltrimethoxysilane in the neutral ethanol solution at 80℃,and the secondary nucleation of the silica nanoparticles during the preparation process could also be inhibited via the optimization of the reaction conditions, such as pH, temperature, colloidal silica sol concentration and the reaction time. The controllable shell thickness and pore size of the synthesized monodisperse CSSMs were successfully obtained by adjusting the weight ratio of silica core/colloidal silica sol and the particle size of colloidal silica sol, respectively. The C18-modified CSSMs with different pore sizes were used to separate small solutes and proteins. The higher efficient separation and relatively low back pressure of the synthesized core-shell column demonstrate that the CSSMs have a great potential application for fast | Guangping Wan Hongjun Xia Jun Wang Jiawei Liu Botao Song Ying Yang Quan Bai | 2018 | Chinese Chemical Letters2018，29，1： | 0 |
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