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A Model to Predict Stall Inception of Transonic Axial Flow Fan/Compressors

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Chinese Journal of Aeronautics 2011年第6期24卷 687-700页

作者： sun Xiaofeng sun Dakun yu Weiwei School of Jet Propulsion Beihang University Beijing 100191 China

A stall inception model for transonic fan/compressors is presented in this paper. It can be shown that under some assumptions the solution of unsteady flow field consists of pressure wave which propagates upstream or downstream, vortex wave and entropy wave convected with the mean flow speed. By further using the mode-matching technique and applying the conservation law and conditions reflecting the loss characteristics of a compressor in the inlet and outlet of the rotor or stator blade rows, a group of homogeneous equations can be obtained from which the stability equation can be derived. Based on the analysis of the unsteady phenomenon caused by casing treatments, the function of casing treatments has been modeled by a wall impedance condition which has been included in the stability model through the eigenvalues and the corresponding eigenfunctions of the system. Besides, the effect of shock waves in cascade channel on the stability prediction is also considered in the stall inception model. Finally, some numerical analysis and experimental investigation are also conducted with emphasis on the mutual comparison.

关键词： stability model rotating stall stall inception transonic compressor unsteady flow

Compactly Supported Distributional Solutions of Nonstationary Nonhomogeneous Refinement Equations

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Acta Mathematica Sinica,English Series 2001年第1期17卷 1-14页

作者： Qi yu sun Department of Mathematics National University of Singapore

Let A be a matrix with the absolute values of all eigenvalues strictly larger than one, and let Z0 be a subset of Z such that n∈Z0 implies n+1∈Z0. Denote the space of all compactly supported distributions by D’, and the usual convolution between two compactly supported distributions f and g by f*g. For any bounded sequence Gn and Hn, n∈Z0, in D’, define the corresponding nonstationary nonhomogeneous refinement equation Φn=Hn*Φn+1（A.）+Gn for all n∈Z0, （*） where Φn, n∈Z0, is in a bounded set of D’. The nonstationary nonhomogeneous refinement equation （*） arises in the construction of wavelets on bounded domain, multiwavelets, and of biorthogonal wavelets on nonuniform meshes. In this paper, we study the existence problem of compactly supported distributional solutions Φn, n∈Z0, of the equation （*）. In fact, we reduce the existence problem to finding a bounded solution Fn of the linear equations n-Sn n+1= n for all n∈Z0, where the matrices Sn and the vectors n, n∈Z0, can be constructed explicitly from Hn and Gn respectively. The results above are still new even for stationary nonhomogeneous refinement equations.

关键词： Nonhomogeneous refinement equation Nonstationary refinement equation Colltinuous refinement equation Refinement equation Wavelets

Fracture Toughness Properties of Three Different Biomaterials Measured by Nanoindentation

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Journal of Bionic Engineering 2007年第1期4卷 11-17页

作者： Ji-yu sun Jin Tong Key Laboratory of Terrain-Machine Bionics Engineering （Ministry of Education China） Jilin University （Nanling Campus） Changchun 130022 P. R. China

The fracture toughness of hard biomaterials, such as nacre, bovine hoof wall and beetle cuticle, is associated with fibrous or lamellar structures that deflect or stop growing cracks. Their hardness and reduced modulus were measured by using a nanoindenter in this paper. Micro/nanoscale cracks were generated by nanoindentation using a Berkovich tip. Nanoindentation of nacre and bovine hoof wall resulted in pile-up around the indent. It was found that the fracture toughness （Kc） of bovine hoof wall is the maximum, the second is nacre, and the elytra cuticle of dung beetle is the least one.

关键词： biomimetics bionics biomaterials nanoindentation laminated structure fracture toughness

Leaching of aluminum from coal spoil by mechanothermal activation

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Frontiers of Chemical Science and Engineering 2015年第2期9卷 216-223页

作者： Xiaoxue sun yuzhu sun Jianguo yu State Key Laboratory of Chemical Engineering East China University of Science and Technology Shanghai 200237 China

The process of order to recover aluminum investigated. The CS was activating coal spoil （CS） in as a high value product was first characterized by X-ray fluorescence （XRF）, X-ray diffraction （XRD） and thermo- gravimetric analysis-differential scanning calorimetry （TGA-DSC） in order to determine the chemical and mineral compositions of the CS. Then a mechanothermal activation method was adopted to increase the aluminum activity in the coal spoil. Over 95% of the aluminum in the CS could be extracted using this activation method. The mechanothermal activation process promoted the destruc- tion of kaolinite structures and hindered the formation of amorphous γ-Al2O3. This resulted in a high aluminum leaching activity in the mechanothermally activated CS.

关键词： coal spoil mechanothermal compound activa-tion leaching

Botanical drug clinical trial: Common issues and future options

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Acta Pharmaceutica Sinica B 2021年第1期11卷 300-303页

作者： yu sun Jiahua Qian Department of Traditional Chinese Medicine and Ethnopharmaceuticals Center for Drug EvaluationNational Medical Products AdministrationBeijing 100022China Center for Drug Evaluation National Medical Products AdministrationBeijing 100022China

In order to understand this disparity between human use and drugs approved by regulatory agencies,we analyzed botanical drug clinical trials registered at *** to detect trends in current trials and guide future trials.A total of 195 botanical drug clinical trials were registered from 2016 to2019,of which 81 are phaseⅡor phaseⅡ/Ⅲ.95%of all phaseⅡandⅡ/Ⅲstudies were designed with100 or less participants per arm,indicating a more observational nature due to the limited power to detect differences in outcomes between treatment and control *** to the limited number of participants,efficacy outcome from results may be highly subjective.14%of the total trials were phaseⅠ*** botanical drugs with well-documented or extensive history of human use,phaseⅠmay not provide significant additional information,and may,therefore,not be *** the trial design,we suggest added-on studies when botanical drugs are used as part of a combination ***,we believe standardized data collection methods and criteria are critical to utilizing the vast collection of human experience as quality evidence to support regulatory approval.

关键词： Traditional Chinese medicine(TCM) Botanical drug Clinical trial Real-world evidence(RWE) Randomized-controlled trial(RCT)

AN ADAPTIVE NONMONOTONIC TRUST REGION METHOD WITH CURVILINEAR SEARCHES

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Journal of Computational Mathematics 2006年第6期24卷 761-770页

作者： Qun-yan Zhou Wen-yu sun School of Mathematics and Computer Science Nanjing Normal University Nanjing 210097 China Department of Mathematics Jiangsu Teacher University of Technology Changzhou 213001 China

In this paper, an algorithm for unconstrained optimization that employs both trust region techniques and curvilinear searches is proposed. At every iteration, we solve the trust region subproblem whose radius is generated adaptively only once. Nonmonotonic backtracking curvilinear searches are performed when the solution of the subproblem is unacceptable. The global convergence and fast local convergence rate of the proposed algorithms are established under some reasonable conditions. The results of numerical ＇experiments are reported to show the effectiveness of the proposed algorithms.

关键词： Unconstrained optimization Preconditioned gradient path Trust region method,Curvilinear search.

A NONMONOTONE SECOND-ORDER STEPLENGTH METHOD FOR UNCONSTRAINED MINIMIZATION

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Journal of Computational Mathematics 2007年第1期25卷 104-112页

作者： Qun-yan Zhou Wen-yu sun Department of Basic Science Jiangsu Teachers University of Technology Changzhou 213001 China School of Mathematics and Computer Science Nanjing Normal University Nanjin9 210097 China School of Mathematics and Computer Science Nanjing Normal University Nanjing 210097 China

In this paper, a nonmonotone method based on McCormick＇s second-order Armijo＇s step-size rule [7] for unconstrained optimization problems is proposed. Every limit point of the sequence generated by using this procedure is proved to be a stationary point with the second-order optimality conditions. Numerical tests on a set of standard test problems are presented and show that the new algorithm is efficient and robust.

关键词： Nonmonotone method Armijo's line search Direction of negative curvature,Unconstrained optimization.

Integrated lifting line/surface panel method for optimal propeller design with consideration of hub effect

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Journal of Hydrodynamics 2019年第6期31卷 1218-1230页

作者： Wen-yu sun Guo-fu Huang China Ship Scientific Research Center Wuxi 214082China

An optimal marine propeller design method is proposed,which integrates the lifting line and surface panel method and is characterized by the use of the surface panel method to take the hub effect into *** developing an integrated approach instead of an iterative method for the calculation of the interaction between the hub and the designed blades,the hub effects on the optimal circulation can be accounted for throughout the theoretical design *** new integrated method provides a fast and accurate enough method to model the straight forward hub surface,in the optimal propeller design.A systematic design procedure from the basic design inputs to the blade geometry determination is performed and the designed propellers are validated by the surface panel method and the RANS *** design and analysis cases are considered by different approaches with comparison and *** a comparative study including different hub geometries is also performed to reveal the mechanism of the hub effect on the distributions of the propeller optimal loads.

关键词： Optimal circulation design lifting line method surface panel method hub effect

Properties and Applications of the Eccentric-gear Drive

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Chinese Journal of Mechanical Engineering 2011年第2期24卷 323-331页

作者： ZHAO yun sun Liang yu Gaohong College of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversiO Hangzhou 310018 China

The eccentric-gear can be used for variable speed ***,due to the vibrations caused by variation of backlash in working process,the eccentric-gear is seldom applied in engineering *** is just a little study about the *** it is necessary to take a further research on eccentric-gear transmission for the applications in the transplanting mechanism of high-speed rice *** key of this paper is to extend understanding of three following characteristics of this drive：（1） The rotation-center-distance and the geometrical-center-distance of the two meshing eccentric gears are respectively the hypotenuse and the straight edge of a right triangle in a cycle.（2） The geometrical center line of two meshing gears divides the linking-line of the two rotational centers equally.（3） When two times the eccentricity of gear,the rotation-center-distance and the geometrical-center-distance form a right triangle,the optimal value of rotation-center-distance can be *** addition,the kinematic analysis,such as the relationship between contact point and midpoint of the linking-line of two gears＇ rotational centers,transmission ratio between the driving-gear and the driven-gear,contact angle and coordinate of contact point are be made,further the formula for calculation of contact force,flow chart for writing optimization program and curve for analysis of data are also be *** relationship between the rotation-center-distance and the geometrical-center-distance,which is determined by three characteristics mentioned above, is a key for the rational design and application of eccentric-gear ***,the presented right triangle property of eccentric gear drive is an important reference for effective analysis of dynamic characteristic of eccentric-gear mechanism and its reliable design.

关键词： eccentric gear transmission property variable speed transmission kinematic and dynamic analysis