检索结果-南通市图书馆

Effects of Airfoil-probe Tubes on the Flow Field of a Compressor Cascade

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2017年第4期26卷 321-330页

作者： ma Hongwei JIN Chao ZHAO Lianpeng ma rong National Key Laboratory of Science and Technology on Aero-Engines Collaborative Innovation Center of Advanced Aero-EngineSchool of Energy&Power EngineeringBeihang UniversityBeijing100191China

To explore the effects of airfoil-probe tubes and its installment position on the flow field of the compressor cas- cade, and find out the mechanism that how the airfoil-probes affect the aerodynamic characteristics of the com- pressor cascade, this paper performed both numerical and experimcntal works on the same compressor cascade. The experiment mainly focused on the cases of low mach number （ma = 0.1）, and cases with different mach numbers （0.1, 0.3, 0.7） and different incidence angles （-5, 0, 5） are investigated by the numerical method. The case without the airfoil-probe tube was referenced as the baseline, and other three cases with the airfoil-probe tubes installed in different chordwise positions O0%, 50%, 70% of the chord length） were studied. The diameter of the airfoil-probe tube is 3ram, which is configured as 300% amplification of some particular airfoil-probe ac- cording to the geometrical similarity principle. The results show that the airfoil-probe tubes have a negative in- fluenc~ on the flow capacity of the cascade at all investigation points. The separations and the large scale stream- wise vortices that induced by the airfoil-probe tube on the pressure side cause most the losses at the high mach number. The influence of the airfoil-probe tube on the flow field in the vicinity of the pressure side surface is lo- cal separation at the low mach number. The airfoil-probe tubes also have a clearly effect on the leakage flow. It decreases the mass flow of the leakage flow and weakens the intensity of the leakage vortex, but enlarges the in- fluence area. The total pressure loss of the case that the tube is installed at the half chordwise position is generally lower than other cases especially at the high mach number, it can even decrease the losses compared with the ba- sic case.

关键词： airfoil-probe compressor cascade installment position 5-hole probe

Effects of a Kind of Surface Groove on Flow Loss in Both Rectangular and Circular Ducts at Different Reynolds Numbers

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2016年第5期25卷 389-393页

作者： ma rong ma Hongwei ZHANG Zhenyang ZHANG Jinghui National Key Laboratory of Science and Technology on Aero-Engines Collaborative Innovation Center of Advanced Aero-EngineSchool of Energy & Power EngineeringBeihang University

Pipes are widely used to transport gas,oil and water in *** reduction in pipes is an increasingly concerned problem to save *** researches have indicated that the non-smooth surface with special structures can reduce flow *** this paper,an experimental investigation has been performed on the effects of a kind of surface groove on the drag in both rectangular and circular duct at different Reynolds *** the experiment of the rectangular duct,total pressure at both inlet and outlet were *** pressure on the wall was measured on the surface with smooth and grooved film *** the circular duct,a boundary layer pressure probe was used to measure the total pressure distribution at both inlet and *** taps at inlet and outlet were used to measure static *** loss coefficient is used to evaluate the effects of the surface groove on drag *** experiment was conducted with the Reynolds number range from 1.28×10~4 to 2.57×10~*** result shows a maximum drag loss reduction of approximately 2.4% in rectangular duct at Reynolds number of 2.4×10~4.A 10%reduction of pipe pressure loss by grooved surface is measured in circular duct at a Reynolds number of 3.0×10~5.

关键词： drag reduction surface groove rectangular duct circular duct

High-efficient solar-driven hydrogen production by full-spectrum synergistic photo-thermo-catalytic methanol steam reforming with in-situ photoreduced Pt-CuO_(x) catalyst

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2022年第8期31卷 460-469,I0012页

作者： Donghui Li Jie Sun rong ma Jinjia Wei School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049ShaanxiChina Adv Energy Sci&Technol Guangdong Lab Foshan Xianhu LabXianhu Hydrogen ValleyFoshan 528200GuangdongChina

Synergy between the intrinsic photon and thermal effects from full-spectrum sunlight for H_(2) production is considered to be central to further improve solar-driven H_(2) *** that end,the photo-thermocatalyst that demonstrates both photoelectronic and photothermal conversion capabilities have drawn much attention ***,we propose a novel synergistic full-spectrum photo-thermo-catalysis technique for high-efficient H_(2) production by solar-driven methanol steam reforming(MSR),along with the Pt-Cu Oxphoto-thermo-catalyst featuring Pt-Cu/Cu_(2)O/CuO heterojunctions by Pt-mediated in-situ photoreduction of Cu *** results show that the H_(2) production performance rises superlinearly with increasing light *** optimal H_(2) production rate of 1.6 mol g^(-1) h^(-1) with the corresponding solar-to-hydrogen conversion efficiency of 7%and the CO selectivity of 5%is achieved under 15×sun full-spectrum irradiance(1×sun=1 k W m^(-2))at 180°C,which is much more efficient than the previously-reported Cu-based thermo-catalysts for MSR normally operating at 250~350°*** attractive performances result from the optimized reaction kinetics in terms of intensified intermediate adsorption and accelerated carrier transfer by long-wave photothermal effect,and reduced activation barrier by short-wave photoelectronic effect,due to the broadened full-spectrum absorbability of *** work has brought us into the innovative technology of full-spectrum synergistic photothermo-catalysis,which is envisioned to expand the application fields of high-efficient solar fuel production.

关键词： Solar-driven Hydrogen production Photo-thermo-catalysis Copper oxide Methanol steam reforming Reaction kinetics optimization

Dealing with the Spatial Synthetic Heterogeneity of Aquifers in the North China Plain:A Case Study of Luancheng County in Hebei Province

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

Acta Geologica Sinica(English Edition) 2012年第1期86卷 226-245页

作者： ma rong SHI Jiansheng LIU Jichao The Institute of Hydrogeology and Environmental Geology ShijiazhuangHebei 050803

The complexity of alluvial-pluvial fan depositional systems makes the detailed characterization of their heterogeneity difficult, yet such a detailed characterization is commonly needed for construction of reliable groundwater models. Traditional models mainly focus on using a single aquifer property to qualitatively or semi-quantitatively characterize the heterogeneity of aquifer, so that they are unable to quantitatively reflect the synthetic heterogeneity of all aquifer properties. In this paper, we propose the heterogeneity synthetic index （HSI） for quantitative characterization of synthetic heterogeneity of an aquifer. The proposed calculation process involves four steps：（1） estimation of the hydraulic conductivity of a sediment sample using the cloud-markov model, （2） establishment of the sedimentary microfacies distribution model through the markov chain, （3） characterization of the distribution model of hydrogeological parameters using the improved sequential simulation method according to the ＂facies-controlled modeling＂ technique, and （4） application of the entropy weight method to calculate the weight coefficient of the above aquifer properties. The HSI of an aquifer is calculated by superposition of these models according to the corresponding weight coefficient. This approach was applied to the Luancheng aquifer deposit in the southeast Hutuo River alluvial-pluvial fan in the North China Plain （NCP）. The results have demonstrated that aquifer 3 which was formed in the middle Pleistocene has the strongest heterogeneity, with an HSI of 0.25-0.75. Aquifer 4 formed in the early Pleistocene shows an intermediate heterogeneity, with the HSI ranging 0.35-0.75. The weakest heterogeneity was found in aquifers 1 and 2 formed in the Holocene and late Pleistocene, with HSI values of 0.40-0.75 and 0.40- 0.80, respectively. The heterogeneity of all the four aquifers is relatively strong in the radial direction of the Huai River alluvial-pluvial fan due to the abrupt

关键词： aquifer heterogeneity hydraulic conductivity porosity markov

Spatial Variation of Hydraulic Conductivity Categories in a Highly Heterogeneous Aquifer： A Case Study in the North China Plain (NCP)

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2017年第1期28卷 113-123页

作者： rong ma Jiansheng Shi Xianyao Shi State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China Institute of Hydrogeology and Environmental Geology Shijiazhuang 050061 China China Geological Survey Beijing 100037 China

Compared with research on spatial variation of hydraulic conductivity（K）, less effort has been made researching different grades of K value in the North China Plain（NCP）. In this study, 3D spatial distribution models of different grades of K were established by considering the effects of clay fraction content and uniformity coefficient（Cu）. The K value can be divided into five grades： very low, low, permeable, high, and very high groups. The volume percentages of these clusters were 3.06%, 36.01%, 55.70%, 4.82%, and 0.41% for the first aquifer; 0.016%, 9.56%, 88.25%, 2.16%, and 0.014% for the second aquifer; and 0.04%, 17.74%, 84.21%, 0.001%, and 0.01% for the third aquifer. It is concluded that the high and very high K values are fully affected by burial depth and that the very low, low, and permeable K values are mainly controlled by depositional environment and are partially influenced by burial depth. The burial depth became the main influencing factor only within the same depositional environment, causing the overall K to decrease with depth. The variations of very low, low, permeable, high, and very high categories of K values with depth are described in this study. This can provide useful information for non-technical decision makers to achieve sustainable development of deep groundwater resources.

关键词： clay fraction content hydraulic conductivity variation depositional environment uni-formity coefficient

Numerical investigation on aerodynamic performance of a bionic flapping wing

在线全文

学校读者我要写书评

暂无评论

Applied mathematics and Mechanics(English Edition) 2019年第11期40卷 1625-1646页

作者： Xinghua CHANG Laiping ZHANG rong ma Nianhua WANG State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000Sichuan ProvinceChina Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000Sichuan ProvinceChina

This paper numerically studies the aerodynamic performance of a bird-like bionic flapping *** geometry and kinematics are designed based on a seagull wing,in which flapping,folding,swaying,and twisting are *** in-house unsteady flow solver based on hybrid moving *** adopted for unsteady flow *** focus on two main issues in this study,i.e.,the influence of the proportion of down-stroke and the effect of span-wise *** results show that the proportion of downstroke is closely related to the efficiency of the flapping *** preferable proportion is about 0.7 by using the present geometry and kinematic model,which is very close to the observed *** finding is that the drag and the power consumption can be greatly reduced by the proper span-wise *** cases with different reduced frequencies are simulated and compared with each *** numerical results show that the power consumption reduces by more than 20%,and the drag coefficient reduces by more than 60% through a proper twisting motion for both *** flow mechanism is mainly due to controlling of unsteady flow separation by adjusting the local effective angle of *** conclusions will be helpful for the high-performance micro air vehicle (maV) design.

关键词： flapping wing bird-like flapping unsteady flow radial basis function (RBF) hybrid dynamic mesh span-wise twisting mechanism

Correlation between the charge radii difference in mirror partner nuclei and thesymmetry energy slope

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第8期48卷 177-184页

作者： Xiao-rong ma Shuai Sun rong An Li-Gang Cao School of Physics Ningxia UniversityYinchuan 750021China Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Key Laboratory of Beam Technology of Ministry of Education Institute of Radiation TechnologyBeijing Academy of Science and TechnologyBeijing 100875China

A correlation between the charge radii difference of mirror partner nucleiΔR_(ch) and the slope parameter L of symmetry energy has been built to ascertain the equation of state of isospin asymmetric nuclear *** this work,the influences of pairing correlations and isoscalar compression modulus on theΔRch are systematically investigated based on the Skyrme energy density functional *** calculated results suggest that the linear correlation betweenΔR_(ch) and L is decreased by the surface pairing *** slope parameter deduced from the difference of charge radii of mirror-pair nuclei ^(32)Ar-^(32)Si,^(36)Ca-^(36)S,^(38)Ca-^(38)Ar,and ^(54)Ni-^(54)Fe falls into the range of L=42.57−50.64 MeV,that is,the rather soft equation of state of asymmetric nuclear ***,the range of the slope parameter can also be influenced by the effective forces classified by various isoscalar incompressibility coefficients.

关键词： symmetry energy charge radius mirror-pair nuclei slope parameter

An efficient large-scale mesh deformation method based on MPI/Open MP hybrid parallel radial basis function interpolation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第5期33卷 1392-1404页

作者： Zhong ZHAO rong ma Lei HE Xinghua CHANG Laiping ZHANG State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China Computational Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China

An efficient MPI/OpenMP hybrid parallel Radial Basis Function (RBF) strategy for both continuous and discontinuous large-scale mesh deformation is proposed to reduce the computational cost and memory *** the conventional parallel methods in which all processors use the same surface displacement and implement the same operation,the present method employs different surface points sets and influence radius for each volume point movement,accompanied with efficient geometry searching *** deformed surface points,also called Control Points (CPs),are stored in each *** displacement of spatial points is interpolated by using only 20-50 nearest control points,and the local influence radius is set to 5-20 times the maximum displacement of control *** shorten the searching time for the nearest control point clouds,an Alternating Digital Tree (ADT) algorithm for 3D complex geometry is designed based on an iterative bisection ***,an MPI/OpenMP hybrid parallel approach is developed to reduce the memory cost in each High-Performance Computing (HPC) node for large-scale *** 3D cases,including the ONERA-M6 wing and a commercial transport airplane standard model with up to 2.5 billion hybrid elements,are used to test the present mesh deformation *** robustness and high parallel efficiency are demonstrated by a wing deflection case with a maximum bending angle of 450 and more than 80% parallel efficiency with 1024 MPI *** addition,the availability for both continuous and discontinuous surface deformation is verified by interpolating the projecting displacement with opposite directions surface points to the spatial points.

关键词： Mesh deformation Moving mesh generation MPI/Open MP hybrid parallel computing Parallel radial basis function interpolation Unstructured hybrid grid

A Tea Buds Counting Method Based on YOLOv5 and Kalman Filter Tracking Algorithm

在线全文

学校读者我要写书评

暂无评论

Plant Phenomics 2023年第2期5卷 164-173页

作者： Yang Li rong ma Rentian Zhang Yifan Cheng Chunwang Dong Key Laboratory of Tea Quality and Safety Control Ministry of Agriculture and Rural AffairsTea Research InstituteChinese Academy of Agricultural SciencesHangzhouChina College of Optical Mechanical and Electrical EngineeringZhejiang A&F UniversityHangzhouChina Tea Research Institute of Shandong Academy of Agricultural Sciences Jinan 250100China College of Mechanical and Electrical Engineering Shihezi UniversityShiheziChina

The tea yield estimation provides information support for the harvest time and amount and serves as a decision-making basis for farmer management and ***,the manual counting of tea buds is troublesome and *** improve the efficiency of tea yield estimation,this study presents a deep-learning-based approach for efficiently estimating tea yield by counting tea buds in the field using an enhanced YOLOv5 model with the Squeeze and Excitation *** method combines the Hungarian matching and Kalman filtering algorithms to achieve accurate and reliable tea bud *** effectiveness of the proposed model was demonstrated by its mean average precision of 91.88%on the test dataset,indicating that it is highly accurate at detecting tea *** model application to the tea bud counting trials reveals that the counting results from test videos are highly correlated with the manual counting results(R^(2)=0.98),indicating that the counting method has high accuracy and *** conclusion,the proposed method can realize tea bud detection and counting in natural light and provides data and technical support for rapid tea bud acquisition.

关键词： estimation conclusion filtering