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Generalized Birkhoan Realization of Nonholonomic Systems

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Generalized Birkhoan Realization of Nonholonomic Systems

第十三届全国非线性振动暨第十届全国非线性动力学和运动稳定性学术会议

作者： Yong-Xin Guo1)Chang Liu2)Shi-Xing Liu1)1College of Physics,Liaoning University,Shenyang 110036,china 2school of aerospace engineering,beijing institute of technology,beijing 100081,china

Based on the Cauchy-Kovalevski theorem for a system of partial dierential equations to be integrable,a kind of generalized Birkhoan systems(GBSs)with local,analytic properties are put forward,whose manifold admits a presymplectic structure described by a closed 2-form which is equivalent to the self-adjointness of the *** relations with Birkhoan systems,generalized Hamiltonian systems are investigated in ***,algebraic and geometric prop-erties of GBSs are formulated,together with their integration methods induced from the Birkhoan *** an important example,nonholonomic systems are reduced into GBSs,which gives a new approach to some open problems of nonholonomic mechanics.

关键词： Birkho’s equations generalized Birkhoan Systems Cauchy-Kovalevski theorem Nonholonomic constraints inverse problem conditions of self-ajointness

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航空器燃烧仓内的静电特性研究

系统仿真学报 2008年第S2期20卷 401-403页

作者：李彦旭崔占忠徐立新陈曦江苏大学电气信息工程学院镇江212013 北京理工大学机电学院北京100081

在对航空器燃烧仓内火焰筒进行建模的基础上,通过仿真的方法得到了火焰筒内碳黑粒子的浓度曲线。利用燃烧仓内的荷电示意图,建立了相应的荷电数学模型,并对其进行了仿真分析,得出了碳黑粒子性质是影响燃烧仓静电特性重要因素的结论。

关键词：燃烧仓静电特性碳黑粒子数值仿真

Investigation of Phase Excitation Effect on Mixing Control in Coaxial Jets

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Journal of Thermal Science 2009年第4期18卷 364-369页

作者： Yanming LIU,Baoguo WANG and Shuyan LIUschool of aerospace engineering,beijing institute of technology,beijing,100081,china school of aerospace engineering Beijing Institute of Technology Beijing China

Detailed unsteady numerical simulation has been carried out to investigate the mechanism of adjacent syntheticjets and the influence of different phases on the mixing of coaxial jets. The results show the combined jet, formedby coupling the vortex pairs at the orifice of two adjacent actuators, can exhibit better controlling effect. Spanwisepressure difference appears because of the existence of phase difference between the left jet and right jet, whichresults in the variation of the combined jet. When the phase difference is greater than zero, mixing enhancementof coaxial jets can be achieved, but there are maximum phase difference and optimal phase difference. On thecontrary, application of adjacent synthetic jets always leads to the mixing reduction when phase difference is lessthan zero.

关键词：混合增强同轴射流控制效果非定常数值模拟喷气飞机励磁合成射流控制作用

Fracture characteristics of concrete subjected to impact loading

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 253-261页

作者： LIU HaiFeng1,2,LIU HaiYan3 & SONG WeiDong1 1 State Key Laboratory of Explosion Science and technology,beijing institute of technology,beijing 100081,china 2 school of Civil and Hydraulic engineering,Ningxia University,Yinchuan 750021,china 3 school of Science,beijing institute of technology,beijing 100081,china State Key Laboratory of Explosion Science and technology Beijing Institute of Technology Beijing China school of Civil and Hydraulic engineering Ningxia University Yinchuan China school of Science Beijing Institute of Technology Beijing China

This paper takes concrete as a four-phase composite made of the intact matrix and three mutually perpendicular groups of penny-shaped micro-cracks. The intact matrix is assumed to be elastic,homogeneous and isotropic,and the micro-cracks are penny-shaped. Combined with the failure mechanism of concrete subjected to impact loading,a dynamic constitutive model for concrete is developed based on Mori-Tanaka's average stress concept and Eshelby's equivalent inclusion theory. Experimental results show that concrete is rate-dependent. The model predictions are in good agreement with the experimental results. The model may be used to simulate the mechanical behavior of concrete under impact loadings.

关键词： concrete micromechanics impact loading constitutive model

The influence of synthetic jet excitation on secondary flow in compressor cascade

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Journal of Thermal Science 2010年第6期19卷 500-504页

作者： Yanming LIU, Tuo SUN, Chaobin GUAN and Baoguo WANG school of aerospace engineering, beijing institute of technology, beijing, 100081, china Assistant Professor school of aerospace engineering Beijing Institute of Technology Beijing China

The detailed numerical simulation has been carried out to investigate the effect of synthetic jet excitation on the secondary flow at 5° incidence in a compressor cascade, in which the synthetic jet actuation is equipped on the suction surface. The influence of excitation position, one fixed near the trailing edge and the other fixed a little far from the trailing edge, has also been studied. The results show that unsteady disturbance of desirable synthetic jet effectively enhances the mixing of the fluid inside the separation region, which reduces the vortex intensity and the energy loss, improves the flow status in the cascade, and also suppresses velocity fluctuation near the trailing edge. Additionally, the actuation fixed near the separation region proves to be more effective and exit load distribution is more uniform due to the employment of the synthetic jet.

关键词：合成射流压气机叶栅二次流激励数值模拟能量损失流体混合涡流强度

Chinese expert consensus on refined diagnosis,treatment,and management of advanced primary liver cancer(2023 edition)

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Chaotic attitude and reorientation maneuver for completely liquid-filled spacecraft with flexible appendage

肝脏研究（英文） 2024年第2期8卷 61-71页

作者： Xiufeng Liu Feng Xia Yue Chen Huichuan Sun Zhengqiang Yang Bo Chen Ming Zhao Xinyu Bi Tao Peng Aizier Ainiwaer Zhiwen Luo Fusheng Wang Yinying Lu National Clinical Research Center for Infectious Diseases Society of Hepatology,beijing Medical Association Translational Medicine Branch,china Association of Gerontology and Geriatrics Department of Medical Oncology Bayi Hospital Affiliated to Nanjing Chinese Medical University NanjingJiangsuChina Department of Hepatobiliary Surgery Southwest HospitalArmy Medical University ChongqingChina Senior Department of Hepatology The Fifth Medical Center of PLA General HospitalBeijingChina Department of Liver Surgery and Transplantation Liver Cancer InstituteZhongshan HospitalFudan UniversityShanghaiChina Department of Interventional Therapy National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina Department of Radiation Oncology National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina Department of Minimally Invasive Interventional Therapy Liver Cancer Study and Service GroupSun Yat-sen University Cancer CenterGuangzhouGuangdongChina Department of Hepatobiliary Surgery National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina Department of Hepatobiliary Surgery The First Affiliated Hospital of Guangxi Medical UniversityNanningGuangxiChina Senior Department of Infectious Diseases The Fifth Medical Center of PLA General HospitalBeijingChina Comprehensive Liver Cancer Center The Fifth Medical Center of PLA General HospitalBeijingChina

Hepatocellular carcinoma(HCC),commonly known as primary liver cancer,is a major cause of malignant tumors and cancer-related deaths in china,accounting for approximately 85％of all cancer cases in the *** guidelines have been used to diagnose and treat liver ***,these guidelines provide a broad definition for classifying advanced liver cancer,with an emphasis on a singular approach,without considering treatment options for individual ***,it is necessary to establish a comprehensive and practical expert consensus,specifically for china,to enhance the diagnosis and treatment of HCC using the Delphi *** classification criteria were refined for Chinese patients with HCC,and the corresponding optimal treatment regimen recommendations were *** recommendations took into account various factors,including tumor characteristics,vascular tumor thrombus grade,distant metastasis,liver function status,portal hypertension,and the hepatitis B virus replication status of patients with primary HCC,along with treatment *** findings and rec-ommendations provide detailed,scientific,and reasonable individualized diagnosis and treatment strategies for clinicians.

关键词： Hepatocellular carcinoma (HCC) Targeted therapy Immunotherapy Refined diagnosis and treatment Expert consensus

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Acta Mechanica Sinica 2009年第2期25卷 271-277页

作者： B. Yue Department of Mechanics, school of Science,beijing institute of technology, 100081 beijing, china Department of Mechanics School of Science Beijing Institute of Technology Beijing China

The present paper investigates the chaotic attitude dynamics and reorientation maneuver for completely viscous liquid-filled spacecraft with flexible appendage. All of the equations of motion are derived by using Lagrangian mechanics and then transformed into a form consisting of an unperturbed part plus perturbed terms so that the system＇s nonlinear characteristics can be exploited in phase space. Emphases are laid on the chaotic attitude dynamics produced from certain sets of physical parameter values of the spacecraft when energy dissipation acts to derive the body from minor to major axis spin. Numerical solutions of these equations show that the attitude dynamics of liquid-filled flexible spacecraft possesses characteristics common to random, non- periodic solutions and chaos, and it is demonstrated that the desired reorientation maneuver is guaranteed by using a pair of thruster impulses. The control strategy for reorientation maneuver is designed and the numerical simulation results are presented for both the uncontrolled and controlled spins transition.

关键词： Nonlinear attitude dynamics Attitude reorientation maneuver Control strategyLiquid-filled spacecraft

The effects of relative density of metal foams on the stresses and deformation of beam under bending

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Acta Mechanica Sinica 2007年第4期23卷 409-414页

作者： Aiyu Zhu Tianyou Fan Department of Mathematics,school of Science,beijing institute of technology,P.O.Box 327,beijing 100081,china Department of Physics,school of Science,beijing institute of technology,P.O.Box 327,beijing 100081,china Department of Mathematics School of Science Beijing Institute of Technology Beijing China Department of Physics School of Science Beijing Institute of Technology Beijing China

The exact analytic solution of the pure bending beam of metallic foams is given. The effects of relative density of the material on stresses and deformation are revealed with the Triantafillou and Gibson constitutive law （TG model） taken as the analysis basis. Several examples for individual foams are discussed, showing the importance of compressibility of the cellular materials. One of the objects of this study is to generalize Hill＇s solution for incompressible plasticity to the case of compressible plasticity, and a kinematics parameter is brought into the analysis so that the velocity field can be determined.

关键词： Metal foams - Relative density Compressible plasticity Constitutive law - TG model

Target selection and transfer trajectories design for exploring asteroid mission

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Science china(Technological Sciences) 2010年第4期53卷 1150-1158页

作者： CUI PingYuan1,QIAO Dong1,CUI HuTao2 & LUAN EnJie3 1 school of aerospace engineering,beijing institute of technology,beijing 100081,china 2 Harbin institute of technology,Harbin 150001,china 3 National Defense Science and Industry Bureau,beijing 100048,china school of aerospace engineering Beijing Institute of Technology Beijing China Harbin institute of technology Harbin China National Defense Science and Industry Bureau Beijing China

Technique of target selection and profiles of transfer trajectory for Chinese asteroid exploring mission are studied systemically.A complete set of approaches to selecting mission targets and designing the transfer trajectory is ***,when selecting a target for mission,some factors regarded as the scientific motivations are ***,when analyzing the accessibility of targets,instead of the classical strategy,the multiple gravity-assist strategy is *** suitable and possible targets,taking into account scientific value and technically feasible,are obtained via selection and *** designing the transfer trajectory for exploring asteroid mission,an approach to selecting gravity-assist celestial body is ***,according to the mission constraints,the trajectory profile with 2-years △V-EGA for exploring asteroid is *** analyzing the trajectory profile,unexpected result that the trajectory would pass by two main-belts asteroids is ***,the original proposal is extended to the multiple flybys *** adds the scientific return for asteroid mission.

关键词： exploring asteroid target selection multiple flybys transfer trajectory