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Effect of the vortical structures on the hydrodynamic performance of a pitching hydrofoil

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Journal of Hydrodynamics 2024年第2期36卷 406-420页

作者： Rui Yuan Hui-yun Hao Qin Wu yun-qing Liu biao Huang School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China

The objective is to study the vortical structural behaviors of a transient pitching hydrofoil and their effects on the hydrodynamic performance. The pitching motion of the hydrofoil is set to pitch up with an almost constant rate from 5° to 15° and then back to 5°, with the Reynolds number 4.4×10^(5) and the frequency 2 Hz. The results show that the main coherent structures around the pitching hydrofoil include small-scale laminar separation bubble (LSB), large-scale second vortex (SV) and trailing edge vortex (TEV) which are all vortical. The relationship between the vortical structure and the lift is investigated with the finite-domain impulse theory. It indicates that the major part of the lift is contributed by the LSB, whereas the shedding and the formation of the SV and TEV cause the fluctuation of the lift. The proper orthogonal decomposition (POD) method is applied to capture the most energetic modes, revealing that the LSB mode occupies a large amount of energy in the flow field. The dynamic mode decomposition (DMD) method accurately extracts the dominant frequency and modal characteristics, with the first mode corresponding to the mean flow, the second mode corresponding to the LSB structure and the third and fourth modes corresponding to the vortex shedding.

关键词： Hydrodynamics vortical structures finite-domain impulse theory proper orthogonal decomposition(POD) dynamic mode decomposition(DMD) Pitching hydrofoil

m Components-Admissible Solutions of Systems of Higher-Order Partial Differential Equations on C^n

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Acta Mathematicae Applicatae Sinica 2008年第2期24卷 211-220页

作者： ling-yun Gao Department of Mathematics Jinan University Cuangzhou 510632 China

Using value distribution theory and techniques in several complex variables,we investigate the problem of existence of m components-admissible solutions of a class of systems of higher-order partial differential equations in several complex variables and estimate the number of admissible components of *** related results will also be obtained.

关键词： m components-admissible solutions several complex variables systems of partial differential equa-tions

An introduction to the novel vacuum plume effects experimental system

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Science China(Technological Sciences) 2016年第6期59卷 953-960页

作者： CAI Guo biao ling Gui Long HE Bi Jiao School of Astronautics Beihang University

This paper introduces a newly developed vacuum Plume effects Experimental System(PES) used for plume effect tests of rocket engines and vacuum heat tests of satellites. The design level, manufacturing technique, and testing capabilities of the PES have reached a highly advanced level at home and abroad. The PES mainly consists of a vacuum chamber, vacuum acquisition system, nitrogen system, helium system, and parameter measurement system. A breakthrough was obtained on the Large Scale Cryo-Pumping System, which was based on a combined liquid nitrogen and liquid helium heat sink. An internal cryopump with a limiting temperature of 4.2 K and an efficient absorption area of 305 m2 was developed. The absorption capability of the cryopump was above 7×107 L/s. Vacuum plume tests were performed in the temperature ranges of ambient temperature, liquid nitrogen, and liquid helium. The experimental results showed that the plume test capability of PES is higher than that of similar foreign equipment STG and CHAFF-4. For 2 g/s and 117 N rocket engines, the dynamic vacuum degree of environment was 8.0×10?4 Pa(approximately 137 km height) and 1.1×10?2 Pa(approximately 106 km height), respectively.

关键词： vacuum plume effect liquid nitrogen heat sink liquid helium heat sink plume absorption pump

Estimating up-limits of eccentricities for the binary black holes in the LIGO-Virgo catalog GWTC-1

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Research in Astronomy and Astrophysics 2020年第11期20卷 283-292页

作者： Qian-yun yun Wen-biao Han Gang Wang Shu-Cheng Yang Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

In the first Gravitational-Wave Transient Catalogue of LIGO and Virgo,all events are announced having zero *** the present paper,we investigate the performance of SEOBNRE,which is a spin-aligned eccentric waveform model in *** comparing with all the eccentric waveforms in SXS library,we find that the SEOBNRE coincides perfectly with numerical relativity *** the SEOBNRE,we re-estimate the eccentricities of all black hole merger *** find that most of these events allow a possibility for existence of initial eccentricities at 10 Hz band,but are totally circularized at the observed frequency(≥20 Hz).The upcoming update of LIGO and the next generation detector like Einstein Telescope will observe the gravitational waves starting at 10 Hz or even *** the eccentricity exists at the lower frequency,then it may significantly support the dynamical formation mechanism taking place in globular clusters.

关键词： gravitational waves stars black holes binaries general

Laboratory insights into the effects of methane hydrate on the anisotropic joint elastic-electrical properties in fractured sandstones

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Petroleum Science 2023年第2期20卷 803-814页

作者： Sheng-biao Liu Tong-Cheng Han Li-yun Fu Shandong Provincial Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)QingdaoShandong266580China Laboratory for Marine Mineral Resources Pilot National Laboratory for Marine Science and TechnologyQingdaoShandong266071China

Fractured hydrate-bearing reservoirs show significantly anisotropic geophysical properties. The joint application of seismic and electromagnetic explorations is expected to accurately assess hydrate resources in the fractured reservoirs. However, the anisotropic joint elastic-electrical properties in such reservoirs that are the key to the successful application of the joint explorations, remain poorly understood. To obtain such knowledge, we designed and implemented dedicated laboratory experiments to study the anisotropic joint elastic-electrical properties in fractured artificial silica sandstones (with fracture density of about 6.2%, porosity of approximately 25.7%, and mean grainsize of 0.089 mm) with evolving methane hydrate. The experimental results showed that the anisotropic compressional wave velocities respectively increased and decreased with the forming and dissociating hydrate, and the variation in the increasing trend and the decreasing extent of the velocity perpendicular to the fractures were more significant than that parallel to the fractures, respectively. The experimental results also showed that the overall decreasing trend of the electrical conductivity parallel to the fractures was steeper than that perpendicular to the fractures during hydrate formation, and the general variations of the two conductivities with complex trend were similar during hydrate dissociation. The variations in the elastic and electrical anisotropic parameters with forming and dissociating hydrate were also found to be distinct. Interpretation of the experimental results suggested that the hydrate binding to the grains evolved to bridge the surfaces of fractures when saturation exceeded 10% during hydrate formation, and the bridging hydrate gradually evolved to floating in fractures during dissociation. The experimental results further showed that the anisotropic velocities and electrical conductivities were correlated with approximately consistent trends of different

关键词： Fractured hydrate reservoirs Elastic anisotropy Electrical anisotropy Joint elastic-electrical properties Hydrate distribution

Static and dynamic studies of adsorption by four macroporous resins to enrich oridonin from Rabdosia rubescens

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Chinese Journal of Chemical Engineering 2021年第4期34卷 151-158页

作者： ling Meng Xia Gui Zhi yun College of Chemical Engineering Nanjing Tech UniversityNanjing 211816China State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine Lunan Pharmaceutical Group Co.Ltd.Linyi 273400China

Oridonin,one of the active ingredients in Rabdosia rubescens(***),has been reported to induce cell apoptosis and cell cycle arrest in many *** extraction methods tend to result in unsatisfied enrichment and poor quality of oridonin present in a given *** paper aims to evaluate the performance and separation characteristics of four different macroporous resins to arrive at the most suitable methodology for the isolation and purification of highquality *** absorption kinetics,thermodynamic and dynamic adsorption were ***20 was selected for further study due to its high adsorption capacity of 32 mgg 1 and desorption ratio with 98.5%.The pseudosecondorder model was considered to be the most suitable for kinetic results,and Langmuir model was chosen to better describe the absorption *** optimum conditions(flow rate of 4 ml min 1,bed depth with 6 cm and initial concentration of 2.15 mg·ml^1),the effective content of oridonin increased from 33.9%to 79.1%in the dry extract with a recovery of 81%and the purity of oridonin improved from 76%to 93%.The results confirm that HP20 provides an efficient method to purify most oridonin from ***.

关键词： Rabdosia rubescens Oridonin Macroporous resin Adsorption Kinetics Thermodynamics

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卷烟仓储数字孪生系统的构建研究

计算机应用文摘 2025年第1期41卷 151-153页

作者：贺彪张云杨军云绍琨马楠云南省德宏州烟草公司云南德宏678400

卷烟仓储数字孪生系统基于数据与三维建模,建立实时数据与模型属性的关联与映射,通过数据驱动实现对实际物理仓储作业过程的多维度、全方位可视化,使仓储状态可视化、作业过程可控。数字孪生技术的应用不仅提高了仓储管理效率,还有效降... 详细信息

卷烟仓储数字孪生系统基于数据与三维建模,建立实时数据与模型属性的关联与映射,通过数据驱动实现对实际物理仓储作业过程的多维度、全方位可视化,使仓储状态可视化、作业过程可控。数字孪生技术的应用不仅提高了仓储管理效率,还有效降低了仓储作业的风险。

关键词：数字孪生智慧仓储数字仓库

Research on Spatial-Temporal Characteristics and Driving Factor of Agricultural Carbon Emissions in China

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Journal of Integrative Agriculture 2014年第6期13卷 1393-1403页

作者： TIAN yun ZHANG Jun-biao HE Ya-ya College of Economics & Management Huazhong Agricultural University Hubei Rural Development Research Center Huazhong Agricultural University

Macroscopic grasp of agricultural carbon emissions status, spatial-temporal characteristics as well as driving factors are the basic premise in further research on China’s agricultural carbon emissions. Based on 23 kinds of major carbon emission sources including agricultural materials inputs, paddy ifeld, soil and livestock breeding, this paper ifrstly calculated agricultural carbon emissions from 1995 to 2010, as well as 31 provinces and cities in 2010 in China. We then made a decomposed analysis to the driving factors of carbon emissions with logarithmic mean Divisia index （LMDI） model. The results show：（1） The amount of agricultural carbon emissions is 291.1691 million t in 2010. Compared with 249.5239 million t in 1995, it increased by 16.69%, in which, agricultural materials inputs, paddy ifeld, soil, enteric fermentation, and manure management accounted for 33.59, 22.03, 7.46, 17.53 and 19.39%of total agricultural carbon emissions, respectively. Although the amount exist ups and downs, it shows an overall trend of cyclical rise; （2） There is an obvious difference among regions：the amount of agricultural carbon emissions from top ten zones account for 56.68%, while 9.84%from last 10 zones. The traditional agricultural provinces, especially the major crop production areas are the main source regions. Based on the differences of carbon emission rations, 31 provinces and cities are divided into ifve types, namely agricultural materials dominant type, paddy ifeld dominant type, enteric fermentation dominant type, composite factors dominant type and balanced type. The agricultural carbon emissions intensity in west of China is the highest, followed by the central region, and the east zone is the lowest; （3） Compared with 1995, efifciency, labor and structure factors cut down carbon emissions by 65.78, 27.51 and 3.19%, respectively;while economy factor increase carbon emissions by 113.16%.

关键词： China agricultural carbon emissions spatial-temporal characteristics driving factor LMDI model

Interaction between strain and vorticity in compressible turbulent boundary layer

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Science China(Physics,Mechanics & Astronomy) 2014年第12期57卷 2316-2329页

作者： CHU You biao WANG Li LU Xi yun Department of Modern Mechanics University of Science and Technology of China

The interaction of strain and vorticity in compressible turbulent boundary layers at Mach number 2.0 and 4.9 is studied by direct numerical simulation(DNS)of the compressible Navier-Stokes *** fundamental characteristics have been studied for both the enstrophy producing and destroying *** is found that large enstrophy production is associated with high dissipation and high enstrophy,while large enstrophy destruction with moderate *** enstrophy production and destruction are also correlated with the dissipation production and ***,the enstrophy producing region has a distinct tendency to be‘sheet-like’structures and the enstrophy destroying region tends to be‘tube-like’in the inner ***,the tendency to be‘sheet-like’or‘tube-like’structures is no longer obvious in the outer ***,the alignment between the vorticity vector and the strain-rate eigenvector is analyzed in the flow *** is noticed that the enstrophy production rate depends mainly on the alignment between the vorticity vector and the intermediate eigenvector in the inner layer,and the enstrophy production(destruction)mainly on the alignment between the vorticity vector and the extensive(compressive)eigenvector in the outer layer.

关键词： direct numerical simulation compressible flow turbulent boundary layer