检索结果-南通市图书馆

Flow separation control over an airfoil using continuous alternating current plasma actuator

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第3期30卷 346-355页

作者： Jian-guo zheng School of Aerospace Engineering Huazhong University of Science and TechnologyWuhan 430074China

The flow separation control over an NACA 0015 airfoil using continuous alternating current(AC)dielectric barrier discharge(DBD)plasma actuator is investigated experimentally and *** work is intended to report some observations made from our experiment,to which little attention is paid in the previous studies,but which is thought to be important to the understanding of control of complex flow separation with AC *** this end,the response of separated flow to AC plasma actuation is visualized through the time-resolved particle image velocimetry(PIV)measurement,whereas numerical simulation is carried out to complement the *** flow control process at chord-based Reynolds number(Re)of 3.31×105 is *** is found that the response of external flow to plasma forcing is delayed for up to tens of milliseconds and the delay time increases with angle of attack *** observed is that at the intermediate angle of attack near stall,the forced flow features a well re-organized flow ***,for airfoil at high post-stall angle of attack,the already well suppressed flow field can recover to the massively separated flow state and then reattach to airfoil surface with the flow pattern fluctuating between the two states in an irregular *** is contrary to one’s first thought that the forced flow at any angles of attack will become well organized and regular,and reflects the complexity of flow separation control.

关键词： dielectric barrier discharge plasma actuator alternating current plasma discharge flow separation flow control delayed response

Two-step harmonic analysis for capturing seasonally-varying amplitudes and phase lags of the predominant tidal constituents

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2020年第7期39卷 165-174页

作者： Anzhou Cao zheng guo Ocean College Zhejiang UniversityZhoushan 316021China Marine Science and Technology College Zhejiang Ocean UniversityZhoushan 316021China

Recent studies have revealed that the predominant tidal constituents have seasonal variations at some ***,how to accurately obtain these variations remains a problem for the traditional harmonic analysis(HA)due to the tradeoff between length of time window and resolution of ***,a method named as"two-step HA"is developed in this study,which consists of both long-and short-time-window *** a series of ideal experiments,practical application at two tidal gauges and comparison with the traditional HA,the feasibility and accuracy of the two-step HA are verified:The two-step HA performs better than the traditional HA in estimating monthly amplitudes and phases for the predominant constituents,whether they have seasonal variability or *** addition to capturing variations of the predominant constituents at tidal gauges,the two-step HA would be useful in investigation of the coherence and incoherence of internal tides.

关键词： tides harmonic analysis seasonal variation tidal gauges

Body size induced changes in metabolic carbon of soil nematodes under N deposition and precipitation regime change in a temperate grassland

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2024年第1期13卷 120-131页

作者： Shuyan Cui Xiaomei Mo guo zheng College of Life Science Shenyang Normal University

Background Global climate change has resulted in precipitation regimes exhibiting an increasing trend in rainfall intensity but a reduction in its frequency. Nitrogen(N) deposition is a crucial component of the global N cycling. Nematode body size is a trait that responds to climate change and is used as a standard trait-based indicator in soil community analysis. Variations in body size influence metabolic carbon(C). We examined the ways by which body size and metabolic C of nematodes respond to changing precipitation regimes and how N deposition regulates these responses by an 8-year manipulative *** Nematode body size was indicated by the community-weighted mean(CWM) mass. We quantified C metabolism components of soil nematodes including production C, respiration C, and corresponding C use efficiency(CUE) under different precipitation intensities and N addition in a semi-arid steppe on the Mongolian Plateau. The Mantel test was used to determine the correlations between CWM, CUE and environmental factors. The partial least squares path modeling(PLS-PM) was conducted to quantify direct or indirect contributions among latent *** We found that heavy precipitation intensity increased the CWM mass of total nematodes and omnivorespredators without N addition. N addition decreased CWM mass of bacterivores across all the precipitation intensity treatments. Stronger precipitation intensities might be favorable for nematode production and respiration C. Variations in the nematode CWM mass drove the CUE to change with N *** Our findings provide new insights into the mechanisms underlying nematode body size and C metabolism, and highlight that explorative studies, such as manipulative experiments, are needed to identify traits underlying size-related effects and to investigate how they affect CUE of nematodes. These efforts may increase our understanding of how changes in precipitation regimes and N deposition may alter soil nema

关键词： Community-weighted mean Metabolic footprint Nitrogen addition Precipitation intensity

Modelling Effect of Circulation Flow Rate on Inclusion Removal in RH Degasser

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2016年第12期23卷 1243-1248页

作者： Shu-guo zheng Miao-yong ZHU School of Metallurgy Northeastern University

Based on the similarity principles, a 1 ： 7 scale physical model was established to study the behavior of molten steel flow and inclusion removal in a 145 t Rheinsahl-Heraeus （RH） degasser. On the basis of the quantitative measurements of the circulation flow rate and inclusion removal under various lifting gas flow rates, the effect of circulation flow rate on inclusion removal was investigated in the RH degasser. The inclusion removal rate shows the trend of first increase and then decrease twice with increasing the circulation flow rate when the circulation flow rates are smaller than 104.7 L/min. Whereas, the inclusion removal rate increases again with the further increase in circu- lation flow rate when the circulation flow rate is larger than 104.7 L/min. At lower circulation flow rates, inclusions are mainly removed by Stokes flotation to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow. At higher circulation flow rates, the collision and aggregation of inclusions improves the inclusion removal efficiency. With the further increase in the circulation flow rate, inclusions are mainly removed by following the turbulent fluctuation （turbulent diffusion） to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow.

关键词： RH degasser lifting gas flow rate circulation flow rate inclusion removal physical modelling

RBFs-MSA Hybrid Method for Mesh Deformation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2012年第4期25卷 500-507页

作者： LIU Yu guo zheng LIU Jun College of Aerospace and Material Engineering National University of Defense Technology Changsha 410073 China School of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

Simulating unsteady flow phenomena involving moving boundaries is a challenging task,one key requirement of which is a reliable and fast algorithm to deform the computational *** basis functions（RBFs） interpolation is a very simple and robust method to deform the ***,the number of operations and the requirement of memory storage will be increased rapidly as the number of grid nodes increases,which limits the application of RBFs to three-dimensional（3D） moving *** submesh approach（MSA） is an efficient method,but its robustness depends on the method used to deform the background mesh.A hybrid method which combines the benefits of MSA and RBFs interpolation,which is called RBFs-MSA,has been *** hybrid method is proved to be robust and efficient via several numerical *** the aspect of the quality of deforming meshes,this hybrid method is comparable with the RBFs interpolation;from the aspect of computing efficiency,one test case shows that RBFs-MSA is about two orders of magnitude faster than RBFs *** these benefits of RBFs-MSA,the new method is suitable for unsteady flow simulation which refers to boundaries movement.

关键词： moving mesh mesh deforming radial basis functions interpolation moving submesh approach CFD

ERM Learning with Unbounded Sampling

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2012年第1期28卷 97-104页

作者： Cheng WANG zheng Chu guo College of Mathematics and Statistics Wuhan UniversityWuhan 430072P.R.China School of Mathematics and Computational Science Sun Yat-Sen UniversityGuangzhou 510275P.R.China

The learning approach of empirical risk minimization （ERM） is taken for the regression problem in the least square framework. A standard assumption for the error analysis in the literature is the uniform boundedness of the output sampling process. In this paper we abandon this boundedness assumption and conduct error analysis for the ERM learning algorithm with unbounded sampling processes satisfying an increment condition for the moments of the output. The key novelty of our analysis is a covering number argument for estimating the sample error.

关键词： Learning theory least square regression ERM covering number

Physical modeling of gas-liquid interfacial fluctuation in a thick slab continuous casting mold with argon blowing

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 704-708页

作者： Shu-guo zheng Miao-yong Zhu School of Materials and Metallurgy Northeastern University Shenyang 110004 China

Combining with the physical model of level fluctuation in a thick slab continuous casting mold with the cross-section of 1500 mm×280 mm and argon blowing, the rationalities of estimating the level fluctuation by three traditional quantitative approaches were discussed, and the effects of gas flowrate, casting speed, and the immersion depth of submerged entry nozzle （SEN） on the level fluctuation were also investigated. As a result, it seems that three traditional quantitative approaches are not very suitable for estimating the level fluctuation in a mold with argon blowing, so a new approach for estimating level fluctuation in the mold with argon blowing was presented. The experimental results show that the level fluctuation is mainly in the region around the nozzle wall. When the casting speeds are larger than a certain value, there is the escape of large bubbles near the nozzle wall, which causes an obvious increase of level fluctuation. Furthermore, optimal process parameters, viz., the gas flowrate of 6 NL/min, the casting speed of 1.1 m/min, and the immersion depth of 170 mm, are presented to restrain the level fluctuation by a physical model.

关键词： slabs continuous casting molds level fluctuation modelling

Tide-Induced Mixing in the Bottom Boundary Layer in the Western East China Sea

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2023年第1期22卷 1-8页

作者： guo zheng CAO Anzhou WANG Jianfeng Marine Science and Technology College Zhejiang Ocean UniversityZhoushan 316022China Ocean College Zhejiang UniversityZhoushan 316021China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

The East China Sea(ECS)boasts a vast continental shelf,where strong tidal motions play an important role in the substance transport and energy *** this study,the tide-induced mixing in the bottom boundary layer in the western ECS is analyzed based on records measured by moored acoustic Doppler current profilers from June to October *** show that the M_(2) tide is strong and shows a barotropic feature,whereas the O_(1) tide is much *** on the M_(2) tidal currents,the eddy viscosity in the bottom Ekman boundary layer is estimated with three *** estimated eddy viscosity values vary within 10^(-4)–10^(-2)m^(2) s^(−1),reaching a maximum at approximately 5 m height from the bottom and decreasing exponentially with the height at all three ***,the shear production of turbulent kinetic energy is calculated to quantify the mixing induced by different tidal *** results show that the shear production of the M_(2) tide is much stronger than that of the O_(1) tide and shows a bottom intensified feature.

关键词： tides East China Sea bottom boundary layer mixing eddy viscosity

维普期刊数据库博看期刊

Emerging topics and new perspectives on regulatory and effector T cells

在线全文

学校读者我要写书评

暂无评论

Journal of Molecular Cell Biology 2012年第1期4卷 1-2页

作者： Song guo zheng Division of Rheumatology and Immunology Department of MedicineUniversity of Southern CaliforniaKeck School of MedicineLos AngelesCA 90033USA East Immunology Institute Tongji UniversityShanghai 200120Chin

It is well accepted that the balance of immunity between effector and regulatory T cells determines the outcome of autoimmune and chronic inflammatory *** the topic of‘Regulatory and Effector T Cells’as published in... 详细信息

关键词： immunity autoimmune cells