检索结果-南通市图书馆

Turbulent boundary layer separation control using plasma actuator at Reynolds number 2000000

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2016年第5期29卷 1237-1246页

作者： Zhang Xin Huang Yong Wang Xunnian Wang Wanbo Tang Kun Li Huaxing School of Aeronautics Northwestern Polytechnical University Xi'an 710072 China China Aerodynamics research and development center Mianyang 621000 China

An experimental investigation was conducted to evaluate the effect of symmetrical plasma actuators on turbulent boundary layer separation control at high Reynolds number. Compared with the traditional control method of plasma actuator, the whole test model was made of aluminum and acted as a covered electrode of the symmetrical plasma actuator. The experimental study of plasma actuators＇ effect on surrounding air, a canonical zero-pressure gradient turbulent boundary, was carried out using particle image velocimetry （PIV） and laser Doppler velocimetry （LDV） in the 0.75 m × 0.75 m low speed wind tunnel to reveal the symmetrical plasma actuator characterization in an external flow. A half model of wing-body configuration was experimentally investigated in the 3.2 m low speed wind tunnel with a six-component strain gauge balance and PIV. The results show that the turbulent boundary layer separation of wing can be obviously suppressed and the maximum lift coefficient is improved at high Reynolds number with the symmetrical plasma actuator. It turns out that the maximum lift coefficient increased by approximately 8.98% and the stall angle of attack was delayed by approximately 2° at Reynolds number 2 ×10……6. The effective mechanism for the turbulent separation control by the symmetrical plasma actuators is to induce the vortex near the wing surface which could create the relatively large- scale disturbance and promote momentum mixing between low speed flow and main flow regions.

关键词： Dielectric barrier discharge Flow control Plasma actuator Turbulent boundary layer Wing-body configuration

Influence of defects in SiC(0001) on epitaxial graphene

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第8期23卷 199-204页

作者：郭钰郭丽伟芦伟黄郊贾玉萍孙伟李治林王逸非 research & development center for Functional Crystals Beijing National Laboratory for Condensed Matter PhysicsInstitute of Physics Chinese Academy of Sciences

Defects in silicon carbide （SIC） substrate are crucial to the properties of the epitaxial graphene （EG） grown on it. Here we report the effect of defects in SiC on the crystalline quality of EGs through comparative studies of the characteristics of the EGs grown on SiC （0001） substrates with different defect densities. It is found that EGs on high quality SiC possess regular steps on the surface of the SiC and there is no discernible D peak in its Raman spectrum. Conversely, the EG on the SiC with a high density of defects has a strong D peak, irregular stepped morphology and poor uniformity in graphene layer numbers. It is the defects in the SiC that are responsible for the irregular stepped morphology and lead to the small domain size in the EG.

关键词： graphene silicon carbide defect

From oxygenated monomers to well-defined low-carbon polymers

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第1期35卷 40-44页

作者： Yanni Xia Chengjian Zhang Yong Wang Shunjie Liu Xinghong Zhang National Key Laboratory of Biobased Transportation Fuel Technology International Research Center for X PolymersDepartment of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China School of Chemistry and Chemical Engineering Huazhong University of Science and TechnologyWuhan 430074China Key Laboratory of Polymer Ecomaterial Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Shanxi-Zheda Institute of Advanced materials and Chemical Engineering Hangzhou 310027China

The synthesis of degradable polymers with easy-to-break in-chain carbon-oxygen bonds has attracted much *** minireview introduces the synthesis of a variety of degradable polymers from the(co)polymerizations of several typical oxygenated monomers such as epoxides,cyclic carbonates,cyclic esters,carbon dioxide(CO_(2)),carbonyl sulfide(COS),and cyclic *** highlight the catalysts and mechanisms for these(co)*** ring-opening copolymerization of five-membered carbonate with cyclic anhydride or COS has been *** also highlight the synthesis of block copolymers and cyclic copolymers with well-defined sequences by the method of growing center *** hope that these new polymerization systems can provide new ideas for the development of degradable low-carbon polymers in the future.

关键词： Polymer synthesis Degradable polymer Low-carbon polymer Catalysis Ring-opening polymerization

Characterization of powder flow properties from micron to nanoscale using FT4 powder rheometer and PT-X powder tester

在线全文

学校读者我要写书评

暂无评论

Particuology 2023年第4期75卷 1-10页

作者： Hui Du Haifeng Lu Jie Tang Haifeng Liu Shanghai Engineering research center of Coal Gasification East China University of Science and TechnologyShanghai200237China

The rapid development of nanotechnology has led to a need to further understand the physical char-acteristics of *** this paper,the flow characteristics of micro-nano alumina particles with different particle sizes were *** FT4 powder rheometer and the PT-X powder tester were used to measure the compression,friction,and dynamic properties of *** compressibility increased significantly as the particle size decreased from 27 μm to 30 *** distribution in the silo was measured and predicted by Janssen's theory,with errors mostly less than 10%.The basic flow energy and the specific energy of the three powders were 4983,1734,and 244 mJ,and 6.80,11.70,and 6.70 mJ/g,respectively,indicating that there was no linear relationship between the change in flowability and particle *** dynamic properties of the powders change from particle-dominated to agglomeration-dominated as the particle size *** conclusion is supported by the results of field emission scanning electron microscopy.

关键词： Micro-nano powders Flow properties Compressibility Frictional properties Pressure distribution

Source and distribution of mercury in natural gas of major petroliferous basins in China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2020年第5期63卷 643-648页

作者： Quanyou LIU Weilong PENG Jian LI Xiaoqi WU State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective development Beijing 100083China research Institute of Petroleum Exploration and Production SINOPECBeijing 100083China research Institute of Petroleum Exploration and development PetroChinaBeijing 100083China research center of Exploration and development in Sichuan Basin Research Institute of Petroleum Exploration and ProductionSINOPECChengdu 610041China

Based on the analysis of the natural gas samples of 146 wells from four major petroliferous basins of China,the source and distribution of mercury in natural gas in major petroliferous basins of China were *** have shown that the mercury concentration of natural gas in petroliferous basins of China varies widely,ranging from 0.01 to 4050μg/m^*** gas well with the highest mercury concentration is in the Xushen gas field in the Songliao *** mercury concentration in the craton basin is relatively low,and the secondary gas reservoir in the Tarim Basin has the lowest mercury *** the rift basin,due to the presence of deep faults which cut the basement and mixing effects of deep fluids,the mercury concentration in natural gas may be abnormally high,*** Xushen gas field in the Songliao *** relatively stable basins where deep and large faults do not develop,mercury is primarily of organic *** rift basins where deep fluids are mixed with gas reservoirs,mercury in natural gas may mainly come from the deep fluids and is characterized by abnormally high mercury concentration and R/Ra values.

关键词： Natural gas Mercury concentration Petroliferous basin Xushen gas field Deep fluids

A MOF/poly(thioctic acid)composite for enhanced gold extraction from water matrices

在线全文

学校读者我要写书评

暂无评论

Nano research 2024年第1期17卷 382-389页

作者： Ruiqing Li Sen Yan Tianwei Xue Rongxing Qiu Yin Li Wenli Hao Guangkuo Xu Yanliang Wang Yanzhen Hong Yuzhong Su Hongtao Wang Shuliang Yang Li Peng Jun Li College of Chemistry and Chemical Engineering Xiamen UniversityXiamen 361005China Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China College of Energy Xiamen UniversityXiamen 361005China National Engineering Laboratory for Green Chemical Productions of Alcohols Ethers and EstersXiamen UniversityXiamen 361005China Collaborative Innovation center of Chemistry for Energy materials Xiamen UniversityXiamen 361005China

With the fast generation of electronic waste(e-waste)and the increasing depletion of metal resources,“urban mining”that can selectively recover gold from secondary resources has attracted great *** of materials with high extraction capacity and satisfying selectivity in complex aqueous-based matrices still remains ***,a novel metal-organic framework/polymer composite(Fe-BTC/poly(thioctic acid),denoted as Fe-BTC/pTA)has been newly synthesized and applied for selective gold recovery in different matrices(river water,seawater,and leaching solution of e-waste).Benefiting from the high specific surface area and suitable pore sizes as well as the rational design of active sites,the composite exhibits high adsorption capacity(920 mg/g),high removal efficiency(>99%),fast kinetics(below 0.1 ppb within 10 min),and good applicability in complex matrices,which are better than those of most reported sulfur-containing ***-state metallic gold with high purity can be effectively enriched due to the high recyclability and long-term stability of the *** material after adsorption can be further applied as a heterogeneous catalyst for water remediation due to the in situ generated gold nanoparticles by the redox reaction between Au(III)ions and the S-containing groups in the composites.

关键词： metal-organic frameworks(MOFs) poly(thioctic acid)(pTA) polymer composites gold recovery urban mining

Numerical investigation of an advanced aircraft model during pitching motion at high incidence

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第2期59卷 276-288页

作者： LIU Jian SUN HaiSheng HUANG Yong JIANG Yong XIAO ZhiXiang School of Aerospace Engineering Tsinghua University Beijing 100084 China China Aerodynamics research and development center Mianyang 621000 China

An unsteady Reynolds averaged Navier–Stokes(URANS) method combined with a rigid dynamic mesh technique was developed to simulate unsteady flows around complex configurations during pitching motion. First, a test case with the NACA0012 airfoil was selected to validate the numerical methods and our in-house codes. Then, we evaluated the unsteady flows around an advanced aircraft model during harmonic pitching motion at high incidence. The effects of pitching motion on the hysteresis of aerodynamic force, the evolution of the leading-edge vortex, and the distribution of pressure on the model's surface were analyzed in detail. The roles of several significant parameters such as the reduced frequency and pitching amplitude were revealed. Several conclusions were found: pitching motion would delay the initiation of the leading-edge vortex, strengthen the vorticity, postpone the occurrence of vortex breakdown, and weaken the massively separated flows, thus causing additional aerodynamic force. Two categories of critical reduced frequency have been found, which divide the influence of reduced frequency on aerodynamic force into three stages, called the linear increasing range, slowly increasing range, and constant range. The first-order phase lag between the aerodynamic force and the incidence is a constant that is independent of the amplitude when the reduced frequency is sufficiently high. A scaled maximum value of C_L is proposed; it depends only on the reduced frequency(instead of the amplitude), and increases linearly when the reduced frequency is sufficiently low.

关键词：俯仰运动飞机模型发病率数值研究 NACA0012翼型非定常流动空气动力高次谐波

Ripple-effect analysis for operational architecture of air defense systems with supernetwork modeling

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2014年第2期25卷 249-264页

作者： Zhigang Zou Fuxian Liu Shiman Sun Lu Xia Chengli Fan School of Air and Missile Defense Air Force Engineering University research & development center China Airport Construction Group Corporation

In order to solve the problem that the ripple-effect analy- sis for the operational architecture of air defense systems （OAADS） is hardly described in quantity with previous modeling approaches, a supernetwork modeling approach for the OAADS is put for- ward by extending granular computing. Based on that operational units and links are equal to different information granularities, the supernetwork framework of the OAADS is constructed as a “four- network within two-layer” structure by forming dynamic operating coalitions, and measuring indexes of the ripple-effect analysis for the OAADS are given combining with Laplace spectral radius. In this framework, via analyzing multidimensional attributes which inherit relations between operational units in different granular scales, an extended granular computing is put forward integrating with a topological structure. Then the operation process within the supernetwork framework, including transformation relations be- tween two layers in the vertical view and mapping relations among functional networks in the horizontal view, is studied in quantity. As the application case shows, comparing with previous modeling approaches, the supernetwork model can validate and analyze the operation mechanism in the air defense architecture, and the ripple-effect analysis can be used to confirm the key operational unit with micro and macro viewpoints.

关键词： operational architecture air defense system super-network model Laplace spectral radius ripple-effect analysis.

Current Status of Natural Products from Plants as Anti-herpes Simplex Virus 1 Agents

在线全文

学校读者我要写书评

暂无评论

Virologica Sinica 2008年第5期23卷 305-314页

作者： Yang-fei XIANG Ying PEI Yi-fei WANG Biomedicine research ＆ development center Jinan University Guangzhou 510630 China

Nucleoside analogues have been the mainstay of clinical treatment of herpes simplex virus 1 (HSV-1) infections since their development. However, the emergence of drug resistant strains has underlined the urgency of the discovery of novel anti-HSV-1 drugs. Natural products, which provided many novel drug leads, are known to be an important source of anti-HSV-1 agents. Herein, we present an overview of natural products with anti-HSV-1 activities isolated from a variety of plants reported in recent years. Several different compounds, mainly belonging to the three groups of polysaccharides, polyphenols and terpenes, showed antiviral effects against HSV-1, indicating their potential to be promising anti-HSV-1 agents.

关键词：抗单纯疱疹病毒植物细胞抗性