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基于非线性浮力频率分布分层流的三波共振畸形波分析

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Acta Mechanica Sinica 2023年第7期39卷 141-151页

作者：殷会敏潘青赵天乐周国荣 Department of Mechanical Engineering University of Hong KongPokfulamHong Kong

本文对位于海洋上层温跃层中的大幅波动进行了理论分析.该内畸形波可能由具有二次非线性的三波共振而引起.虽然三波共振中的畸形波精确解析解已经在数学物理文献中被推导出,但其在流体动力学中的应用尚未被充分研究.本文计算了在非线性... 详细信息

本文对位于海洋上层温跃层中的大幅波动进行了理论分析.该内畸形波可能由具有二次非线性的三波共振而引起.虽然三波共振中的畸形波精确解析解已经在数学物理文献中被推导出,但其在流体动力学中的应用尚未被充分研究.本文计算了在非线性浮力频率分布下三波共振演化方程中的系数.调制不稳定性是指由色散和非线性效应之间的相互作用引起的干扰增长,虽然不稳定性分析是基于线性化研究的,但来自增长率谱的信息可以与畸形波的非线性、数值鲁棒性测试的结果相关联.最后,通过解析延拓将空间变量扩展为复数进行了解析畸形波解的极点分析.对于具有一个或两个峰值的畸形波,物理空间中最大位移的位置与轨迹转折点处的极点的实部相同或近似相等.这些数值和分析研究构成了理解海洋上层大规模瞬态运动的框架.

关键词：数学物理二次非线性调制不稳定性解析延拓空间变量分层流精确解析解非线性效应

General optimal design of solar-powered unmanned aerial vehicle for priority considering propulsion system

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Chinese Journal of Aeronautics 2020年第8期33卷 2176-2188页

作者： Xinhua LI Kaijun sun Feng LI School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China CH UAV Technology Co. LtdChina Academy of Aerospace AerodynamicsBeijing 100()74China

This paper describes the general optimization design method of Solar-Powered Unmanned Aerial Vehicle which priority considering propulsion system planning. Based on the traditional solar powered aircraft design method, the propulsion system top-level target parameters which affect the path planning are integrated into the general optimization design. According to the typical mission requirements of Solar-Powered Unmanned Aerial Vehicle, considering the design variables such as wing area, aspect ratio, design mission date and so on, the general optimization is carried out with the minimum aircraft weight as the optimization objective. The influence of wing area and aspect ratio on the optimal design results is analyzed and compared with the traditional design method. The results show that the general design method of Solar-Powered Unmanned Aerial Vehicle for priority considering propulsion system can greatly reduce the electricity demand of energy storage battery, greatly reduce the aircraft weight of Solar-Powered Unmanned Aerial Vehicle.

关键词： Aircraft design optimization General design technology Route analysis Solar-powered Unmanned aerial vehicle

Effect of Tai Chi Chuan on serotonin and cortisol for monitoring stress and quality of life in post-treatment breast cancer patients

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中华乳腺病杂志（电子版） 2014年第4期8卷 34-40页

作者： William Wai Nam Tsang wings Tjing Yung Loo Louis wing Cheong chow Elizabeth Lam Yan Ng Adrian Yun San Yip Jianping Chen Department of Rehabilitation Sciences Hong Kong Polytechnic University UNIMED Medical Institute and Organisation for Oncology and Translational Research School of Chinese Medicine Li Ka Shing Faculty of MedicineUniversity of Hong Kong

Objective Immediate physical exercise has been recommended for patients in the recovery phase to improve survival and quality of life(QOL)and reduce recurrence of *** new NCCN Guidelines for Survivorship also highlighted the role of exercise in post-cancer health,encouraging patients to perform light physical activity following *** aim of our study is to effect of Tai Chi Chuan(TCC)on serotonin and cortisol for monitoring stress and QOL in post-treatment breast cancer *** Totally85 post-treatment breast cancer patients were enrolled in this study to observe the effects of practicing TCC on recovery,as well as stress and happiness which are indicators of QOL of in *** blood was drawn from study subjects to analyze the levels of serotonin,cortisol and high sensitive C-reactive protein(HSCRP)at baseline,and at 3,6 and 12 months of TCC *** was drawn from healthy subjects only at baseline.A QOL questionnaire was administered to study subjects at three time points throughout the study,and once for healthy *** data were processed by analysis of variance of repeated *** At 3,6 and 12 months time points following regular TCC exercise,WBC,RBC,hemoglobin in blood samples showed a statistically significant difference(F=161.55,172.14,289.73;all P=0.00);the level of serotonin(biomarker for well-being),cortisol(indicator of stress)and HS-CRP(biomarker for inflammation)showed a statistical improvement(F=307.46,182.85,102.23;all P=0.00).After 3,6 and 12 months of regular TCC exercise,according to the results of QOL questionnaire,the indicators including quality of sleep,perceived hunger,fatigue,contentment,stress and social interaction presented a significant difference(F=312.98,222.64,543.90,46.05,28.10,78.92,all P<0.05),while there was no statistical difference in life dissatisfaction(F=56.61,P=0.166)Conclusions TCC physical activity for post-treatment breast cancer patients improved QOL and overall

关键词：乳腺病患者临床分析治疗方法

Preface: Frontiers in Astrophysics(Ⅱ)——A special issue dedicated to the 20th anniversary of RAA(2001–2020)

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Research in Astronomy and Astrophysics 2020年第10期20卷 157-159页

作者： Jingxiu Wang wing-Huen Ip University of Chinese Academy of Sciences Beijing 100049 National Astronomical Observatories Chinese Academy of SciencesBeijing 100101 Institute of Astronomy “National”Central UniversityZhongliTaoyuan 32049

On the arrival of the 20 th anniversary of the journal,Research in Astronomy and Astrophysics(RAA),we see rapid progress in the frontiers of astronomy and *** celebrate the birth and growth of RAA,a special issue consisting of 11 invited reviews from more than 30 authors,mainly from China,has been *** is the second volume of the special issues entitled Frontiers in Astrophysics published in *** publication aims at evaluating the current status and key progress in some frontier areas of astronomy and astrophysics with a spirit of guiding future studies.

关键词： galaxies:statistics Galaxy:structure stars:binaries,black holes planetary systems sun:CMEs,filaments,magnetic fields astronomical instrumentation,methods and techniques

Optimization of Nonlinear Energy Sink for Vibration Suppression of Systems Under Dual-Frequency Excitation

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第6期35卷 986-991页

作者： sun Bin Wu Zhiqiang School of Mechanical Engineering Tianjin Key Laboratory of Nonlinear Dynamics and Chaos ControlTianjin University School of Aeronautical Engineering Civil Aviation University of China

Aiming to decrease the vibration of wing induced by dual-rotor civil turbofan engines,the dynamic models of a single-degree of freedom (DOF) linear main oscillator coupled with single-DOF and two-DOF nonlinear energy sink (NES) are *** to the related energy criteria for the optimization of the dynamic vibration absorber,focusing on the effects of external excitation on the kinetic energy of the primary mass and total system energy,the vibration suppression effects of single-DOF,two-DOF serial and parallel NES on the main oscillator system are *** the condition that the characteristic parameters of the main oscillator system and additional total mass of the vibration absorber remain unchanged,results show that the two-DOF parallel NES has the best vibration energy suppression effects,which can provide data reference for the optimal design of NES vibration suppression under dual-frequency excitation.

关键词： nonlinear energy sink(NES) civil turbofan engine dual-frequency vibration suppression optimization

Dynamic flight stability of hovering insects

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Acta Mechanica Sinica 2007年第3期23卷 231-246页

作者： Mao sun Jikang Wang Yan Xiong Institute of Fluid Mechanics Beihang UniversityBeijing 100083 China

The equations of motion of an insect with flapping wings are derived and then simplified to that of a flying body using the ＂rigid body＂ assumption. On the basis of the simplified equations of motion, the longitudinal dynamic flight stability of four insects （hoverfly, cranefly, dronefly and hawkmoth） in hovering flight is studied （the mass of the insects ranging from 11 to 1,648 mg and wingbeat frequency from 26 to 157Hz）. The method of computational fluid dynamics is used to compute the aerodynamic derivatives and the techniques of eigenvalue and eigenvector analysis are used to solve the equations of motion. The validity of the ＂rigid body＂ assumption is tested and how differences in size and wing kinematics influence the applicability of the ＂rigid body＂ assumption is investigated. The primary findings are：（1） For insects considered in the present study and those with relatively high wingbeat frequency （hoverfly, drone fly and bumblebee）, the ＂rigid body＂ assumption is reasonable, and for those with relatively low wingbeat frequency （cranefly and howkmoth）, the applicability of the ＂rigid body＂ assumption is questionable. （2） The same three natural modes of motion as those reported recently for a bumblebee are identified, i.e., one unstable oscillatory mode, one stable fast subsidence mode and one stable slow subsidence mode. （3） Approximate analytical expressions of the eigenvalues, which give physical insight into the genesis of the natural modes of motion, are derived. The expressions identify the speed derivative Mu （pitching moment produced by unit horizontal speed） as the primary source of the unstable oscillatory mode and the stable fast subsidence mode and Zw （vertical force produced by unit vertical speed） as the primary source of the stable slow subsidence mode.

关键词： Insect Dynamic stability Equations of motion Navier-Stokes simulation Natural modes of motion

A CRACK CLOSURE MODEL FOR BRITTLE ROCK SUBJECTED TO COMPRESSIVE-SHEAR LOADING

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中国有色金属学会会刊：英文版 1999年第2期9卷 223-228页

作者： Chen, F sun, ZQ Xu, JC Cent S Univ Technol Opening Lab Mech Changsha 410083 Peoples R China

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１ＩＮＴＲＯＤＵＣＴＩＯＮＣｏｍｐｒｅｓｓｉｏｎｓｈｅａｒｆｒａｃｔｕｒｅｏｆｒｏｃｋｗａｓｉｎｖｅｓｔｉｇａｔｅｄｂｙｍａｎｙｒｅｓｅａｒｃｈｅｒｓ，Ｒａｏｅｔａｌ［１］ｓｔｕｄｉｅｄｔｈｉｓｆａｉｌｕｒｅｍｏｄｅｕｓｉｎｇｆｏｕｒｐｏｉｎｔｂ...

关键词： crack closurecompressiveshear loadingstress intensity factor

Drag reduction and flow structures of wing tip sails in ground effect

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Journal of Hydrodynamics 2020年第1期32卷 93-106页

作者： Jian-xun Zhou Cheng-hong sun Daichin Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai 200072China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai UniversityShanghai 200072China

The hydrodynamics and flow structures of a base wing slotted with tip sails in proximity to the ground were studied experimentally in order to investigate the flow control efficiency of wing tip sails in ground *** experiment was conducted in a towing tank at a Reynolds number 1.5×10^*** lift and drag forces were measured by a transducer,the velocity fields of the wing tip vortices were measured using a time-resolved particle image velocimetry system(TR-PIV).The tip-sails and ground clearance were both effective in reducing the total drag,the lift coefficients of the tip-sails wings were increased as compared with that of a base *** lift-drag ratios of the tip-sails wings were improved obviously in a range of angles of attack from 2°to stalling *** tip-sails played more important role in unwinding the concentrated wing tip vortices at higher angle of attack,the intensity of the tip vortices were much weaker than that of the base *** development of the wing tip vortices was suppressed as well due to the inhibition of the ground,the downwash speed was reduced and the induced drag was decreased.

关键词： wing tip-sails ground effect lift/drag force vorticity distribution induced drag reduction

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钟乳石的本草考证、品质评价及物相分析

中国实验方剂学杂志 2024年第21期30卷 203-211页

作者：魏健雄孙媛陈代红王友邵章敏李娟湖北中医药大学药学院武汉430065

该文通过查阅历代本草、医书与经典名方及现代文献,对钟乳石的名称、基原和品质评价等进行系统整理与本草考证,结合对20批样品的物相分析,以期为钟乳石品质评价提供依据。考证表明,清代前的本草多以“石钟乳”之名记载,并有“虚中”“... 详细信息

该文通过查阅历代本草、医书与经典名方及现代文献,对钟乳石的名称、基原和品质评价等进行系统整理与本草考证,结合对20批样品的物相分析,以期为钟乳石品质评价提供依据。考证表明,清代前的本草多以“石钟乳”之名记载,并有“虚中”“夏石”“黄石砂”等;此外,有孔公孽、殷孽、乳床、乳华等别名混用现象,现代多以钟乳石为正名。本草记载的钟乳石与现代碳酸盐类矿物方解石族方解石相符,形状略呈圆锥形或圆柱形,大多有白、灰、黄3种颜色,中心常有孔洞,碳酸钙(CaCO_(3))质量分数在95%以上。历代品质评价包括“鹅翎管”“蝉翼”“明白”“光润”等,更注重光泽;现代评价包括“色白、空心、有亮光,多层纹、断面具闪星状亮光”等特征。扫描电镜下钟乳石可见明显的层纹特征,颗粒大小均匀,而鹅管石呈不规则状;通过不同批次的钟乳石的性状、微性状对比,X射线衍射(XRD)检测和CaCO_(3)含量测定等,不同批次钟乳石药材物相组成大致相似,均以方解石为主,另含镁方解石,“光润”“闪星状亮光多”者CaCO_(3)质量分数相对更高,为其品质评价的关键特征,“色白”可作为品质参考,“层纹”“乳头状突起”可作为药材鉴定特征,与本草考证结果基本一致。该研究结果为矿物类药物的质量评价提供参考,以期更好地指导临床用药和资源合理利用。

关键词：钟乳石品质评价本草考证碳酸钙方解石 X射线衍射(XRD) 物相分析