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The generalized quasi-variational principles of non-conservative systems with two kinds of variables

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Science China(Physics,Mechanics & Astronomy) 2005年第5期48卷 600-613页

作者： LIANG Lifu liu Diankui song Haiyan School of Civil Engineering Harbin Engineering University Harbin 150001 China School of Civil Engineering Harbin Engineering University Harbin 150001 China School of Civil Engineering Harbin Engineering University Harbin 150001 China

According to the corresponding relations between general forces and general displacements, the balancing and geometrical equations of elasticity are multiplied by the corresponding virtual quantities, integrated with volume and area, and then added algebraically. Proceeding to the next step, by substituting constitutive relation and considering that body force and surface force are both fellow forces, the generalized quasi-variational principles with the two kinds of variables of the first type are established in non-conservative systems. Through substituting another constitutive relation, using similar methods as above, the generalized quasi-variational principles with the two kinds of variables of the second type are established in non-conservative systems. By using the generalized quasi-complementary energy principles with the two kinds of variables of the first type, a method for solving two kinds of variables (internal force and deformation) is given for non-conservative systems of the typical fellow forces.

关键词： non-conservative system, generalized variational principle, two kinds of variables.

Experimental Study on the Film Cooling Characteristics of Three Complex Tip Structures

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Journal of Thermal Science 2023年第4期32卷 1378-1392页

作者： LIN Juqiang LI Haiwang YOU Ruquan liu Runzhou TAO Zhi liu song School of Energy and Power Engineering Beihang UniversityBeijing100191China Research Institute for Aero-Engines Beihang UniversityBeijing100191China National Key Laboratory of Science and Technology on Aero Engines Aero-thermodynamics Beijing100191China AECC Sichuan Gas Turbine Establishment Sichuan610500China

The turbine blades of aircrafts must be properly cooled to prevent engine ***,to investigate the influence of the tip structure on the film cooling effect,pressure-sensitive paint test technology was used to determine the adiabatic film cooling effectiveness in this *** experiment was completed in a cascade comprising three straight *** effects of the blowing ratio,density ratio,tip clearance,and tip structure on film cooling efficiency were *** experimental results demonstrated that,as the blowing ratio increased,the film coverage area and film cooling efficiency increased under most experimental ***,the film cooling efficiency was found to initially increase,and subsequently decrease,as the blowing ratio *** respective influences of the density ratio and tip clearance on the film cooling efficiency were found to be *** density ratio experiments revealed that a high-density ratio can result in better film coverage than the low-density-ratio *** tip clearance experimental results indicated that a small tip clearance promotes an increase in film cooling efficiency;this is because the small tip clearance negatively affects the main stream leakage flow,which can reduce the film coverage *** the conditions of the Base case 2 configuration,a blowing ratio of 2.1,and a tip clearance of 0.6%h,the average film cooling efficiency of the blade tip was *** the three blade tip structures applied in this study,Base case 2 demonstrated higher film cooling efficiency than the other two blade tip structures under the conditions of the same blowing ratio,tip clearance,and density ratio.

关键词： film cooling tip structure pressure-sensitive paint leakage flow

The impact of temperature on the evolution and self-deflection of spatial optical solitons in photovoltaic photorefractive media

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Chinese Science Bulletin 2009年第9期54卷 1470-1476页

作者： ZHANG GuangYong liu Jin song Department of Physics China University of Geosciences Wuhan 430074 China Wuhan National Laboratory for Optoelectronics School of Optoelectronic Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

The temperature effects on the evolution and self-deflection of bright spatial optical solitons in photo-voltaic photorefractive media were investigated by taking into account diffusion effects. The numerical results show that the evolution of the bright solitary beam depends strongly on the crystal temperature. It is also found that the bending distance of the bright solitary beam centre increases and reaches its maximum value at a characteristic temperature, and then decreases as temperature rises and ap-proaches zero at low and high temperatures. Both the maximum value and characteristic temperature increase with the input power density. The self-deflection of bright solitary beam is further studied by a perturbation technique, and the results are found to be in good agreement with that obtained by the numerical method. The diffusion process and the dark irradiance dominate the temperature depend-ence of bending distance in most values of temperature besides at the characteristic temperature and in the higher temperature regime. The diffusion process will mainly dominate the temperature dependence at the characteristic temperature and the dark irradiance will dominate in the higher tem-perature range.

关键词：晶体温度空间光孤子媒体光折光伏挠度温度依赖性特征温度

Numerical and experimental investigation into hypersonic boundary layer transition induced by roughness elements

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Chinese Journal of Aeronautics 2019年第3期32卷 559-567页

作者： Hao DONG Shicheng liu Xi GENG song liu Liming YANG Keming CHENG Department of Aerodynamics Nanjing University of Aeronautics and Aeronautics Department of Mechanical Engineering National University of Singapore

In this work, the Direct Numerical Simulation(DNS) and Oil-Film Interferometry(OFI)technique are used to investigate the hypersonic boundary layer transition induced by single and double roughness elements at Mach number 5. For single roughness, the DNS results showed that both horseshoe vortices and hairpin vortices caused by shear layer instability can affect the boundary layer instability. The generation of the near-wall unstable structure is the key point of boundary layer transition behind the roughness element. At the downstream of the roughness element, the interaction between horseshoe vortices and hairpin vortices will spread in the spanwise *** double roughness elements, the effect of the spacing between roughness elements on the transition is studied. It is found that the case of higher spacing between roughness elements is more effective for inducing transition than the lower one. The interaction between two adjacent roughness elements can suppress the evolution of horseshoe vortices in the downstream and trigger the instability of shear layer. Thus, the transition will be suppressed accordingly.

关键词： Boundary layer transition Hypersonic Direct numerical simulation (DNS) Oil-film interferometry Roughness elements

A Comparison Study of Wear and Fretting Fatigue Behavior Between Cr-alloyed Layer and Cr-Ti Solid-solution Layer

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 782-792页

作者： Shou-Ming Yu Dao-Xin liu Xiao-Hua Zhang Cheng-song liu School of Aeronautics Institute of Corrosion and ProtectionNorthwestern Polytechnical University

This work reported a comparison between the wear and fretting fatigue（FF） behaviors of a Cr-alloyed layer and a Cr-Ti solid-solution *** hardness and toughness of both layers were evaluated to support this *** results showed that the Cr-alloyed layer had high surface hardness but poor toughness,while the Cr-Ti solid-solution layer had excellent toughness but low *** FF properties of the modified Ti6A14 V alloy depended on the trade-off between two factors：wear resistance and fatigue *** the Cr-alloyed layer could effectively resist the wear in fretting areas,its poor toughness caused the fatigue resistance to drop sharply and hence led to a premature failure in FF *** to the relatively good fatigue resistance,the Cr-Ti solid-solution layer had slightly higher FF life than that of the Cr-alloyed layer;however,its low hardness resulted in severe wear in correspondence with the fretting area and thus a failure to improve the FF properties of Ti6A14 V *** combined with shot peening post-treatment,the FF life of both layers increased by about three times compared to that of the Ti6A14 V alloy.A further study showed that the poor toughness or low hardness still exerted negative influence on combination-treated samples.

关键词： Titanium alloy Plasma chromizing Shot peening Fretting fatigue Wear

基于邓肯-张模型的土工膜心墙堆石坝应力应变分析

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中国农村水利水电 2025年第1期 215-220,226页

作者：刘松成王可熊将胡索奥王涛武汉大学水资源工程与调度全国重点实验室湖北武汉430072 中国电建集团北京勘测设计研究院有限公司北京100024

研究利用FLAC3D软件提供的二次开发平台,在VC++环境下开发了邓肯-张本构模型,并通过数值模拟三轴压缩试验验证了开发模型的准确性。在此基础上建立了某土工膜心墙堆石坝(最大坝高78 m)的三维数值计算模型,并分析了竣工期和蓄水期两种工... 详细信息

研究利用FLAC3D软件提供的二次开发平台,在VC++环境下开发了邓肯-张本构模型,并通过数值模拟三轴压缩试验验证了开发模型的准确性。在此基础上建立了某土工膜心墙堆石坝(最大坝高78 m)的三维数值计算模型,并分析了竣工期和蓄水期两种工况下的应力应变规律。研究结果表明,心墙底部与混凝土基座连接处存在应力集中现象,心墙中应力分布出现明显的拱效应,采用有效应力法判断心墙尚未达到水力劈裂发生的条件,表明心墙堆石坝在目前的工况下是稳定的。

关键词：邓肯-张模型堆石坝土工膜应力应变 FLAC3D

Application of Bayesian Compressive Sensing in IR-UWB Channel Estimation

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China Communications 2017年第5期14卷 30-37页

作者： song liu Shaohua Wu Yang Li Harbin Institute of Technology Shenzhen Graduate School Shenzhen 518055China

Due to the sparse nature of the impulse radio ultra-wideband(IR-UWB)communication channel in the time domain,compressive sensing(CS)theory is very suitable for the sparse channel estimation. Besides the sparse nature,the IR-UWB channel has shown more features which can be taken into account in the channel estimation process,such as the clustering structures. In this paper,by taking advantage of the clustering features of the channel,a novel IR-UWB channel estimation scheme based on the Bayesian compressive sensing(BCS)framework is proposed,in which the sparse degree of the channel impulse response is not required. Extensive simulation results show that the proposed channel estimation scheme has obvious advantages over the traditional scheme,and the final demodulation performance,in terms of Bit Error Rate(BER),is therefore greatly improved.

关键词： cluster Bayesian compressive sensing ultra wideband channel estimation

Boundary Regularity of Isometries Between Infinitely Flat Complex Domains

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1375-1387页

作者： Jin song liu Fei TAO Hong Yu WANG Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190P.R.China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049P.R.China Beijing International Center for Mathematical Research Peking UniversityBeijing 100871P.R.China School of Science Beijing University of Posts and TelecommunicationsBeijing 100876P.R.China Key Laboratory of Mathematics and Information Networks(Beijing University of Posts and Telecommunications) Ministry of EducationBeijing 100876P.R.China

In this paper we prove that isometries with respect to the Kobayashi metric between certain domains having boundary points at which the boundary is infinitely flat extend continuously to the *** strategy is to reestab... 详细信息

关键词： Boundary extension Kobayashi metric isometries

Quantitative characterization of fusion state of virgin and aged asphalt using nano-ferrous ferric oxide tracer

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 467-480页

作者： Qiang Li song liu Huameng Wen Zhou Zhou College of Civil Engineering Nanjing Forestry UniversityNanjing 210037China School of Transportation Southeast UniversityNanjing 211189China

The exact evaluation of the fusion rate of virgin and aged asphalt is essential to optimize the performance of the recycled asphalt *** fusion rate index was developed by tracing the distribution of tracer asphalt,which contains nano-ferrous ferric oxide(nano-Fe_(3)O_(4))*** fusion simulation tests were performed on three types of asphalt to obtain different fusion states,and fatigue tests were performed to evaluate the influence of the fusion rate on the fatigue life of the recycled *** was found that the tracer asphalt containing 4%nano-Fe_(3)O_(4)shows the optimal trace effect,and the developed fusion rate index can quantitatively characterize the influence of different factors on the fusion state of the recycled *** fusion state is closely related to the fatigue performance of recycled asphalt,and the fusion rate index can fairly evaluate its fatigue *** relationship between the fusion rate and the fatigue life of recycled asphalt depends on the factors that cause the fusion rate *** the influence of the amount of rejuvenator,the fatigue life of recycled asphalt grows exponentially with increasing fusion rate due to enhancement of molecular motion as well as a supplement of lightweight *** the influence of heat preservation treatment,fatigue life increases linearly with increasing fusion *** proposed fusion rate index can be utilized to quantitatively characterize the fusion state of virgin and aged asphalt,thus providing a simple way to guide the practical application of recycled asphalt.

关键词： Recycled asphalt Rejuvenator Tracing technique Fusion rate Fatigue