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A Note on Weighted Composition Operators on the Weighted Bergman Space

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Acta Mathematica Sinica,English Series 2015年第6期31卷 947-952页

作者： Lian Kuo zhao sheng zhao HOU School of Mathematics and Computer Science Shanxi Normal University School of Mathematics Science Soochow University

This paper gives a note on weighted composition operators on the weighted Bergman space, which shows that for a fixed composition symbol, the weighted composition operators are bounded on the weighted Bergman space on... 详细信息

关键词： Weighted Bergman space weighted composition operator boundedness finite Blaschke product

Numerical simulations of propeller cavitation flows based on OpenFOAM

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Journal of Hydrodynamics 2020年第6期32卷 1071-1079页

作者： Min-sheng zhao Wei-wen zhao De-cheng Wan Computational Marine Hydrodynamics Lab(CMHL) State Key Laboratory of Ocean EngineeringSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

In order to study the cavitation and hydrodynamic characteristics of propeller under uniform and non-uniform flows,numerical investigations are performed using interPhaseChangeDyMFoam in the open source computational fluid dynamics(CFD)software platform OpenFOAM with Schnerr-Sauer cavitation *** simulation results can be used as a reference to evaluate the working ability of a propeller in case of actual navigation.A new grid encryption method is adopted in the research to better capture the existence of vortex cavitation at the propeller *** method of function input is carried out in the study to simulate the condition of non-uniform flow and reduce the calculation *** unsteady dynamics are predicted by the Reynolds-averaged Navier-Stokes(RANS)method with a modified shear stress transport(SST)k−ωturbulence *** numerical results of the propeller such as cavitation shape and pressure distribution under uniform and non-uniform flow are analyzed and compared with each other.

关键词： OpenFOAM E779A propeller cavitation non uniform flow

Laboratory assessment of Alaska aggregates using Micro-Deval test

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Frontiers of Structural and Civil Engineering 2017年第1期11卷 27-34页

作者： Jenny LIU sheng zhao Anthony MULLIN Department of Civil and Environmental Engineering University of Alaska Fairbanks Fairbanks AK 99775-5900 USA Center for Environmentally Sustainable Transportation in Cold Climates Institute of Northern Engineering University of AlaskaFairbanks Fairbanks AK 99775-5900 USA

Aggregates suitable for use in asphalt concrete （AC） pavement construction must meet durability criteria. Thus, it is critical to select appropriate tests to properly characterize aggregate durability. In Alaska, durability tests currently being used for aggregates in AC pavement include Los Angeles （LA） abrasion test, sulfate soundness test and Washington degradation test. However, there have long been concerns arising over Washington degradation test used as an acceptance tool, motivating pavement practitioners to seek more suitable alternatives. This paper presents a study to investigate the feasibility of using Micro-Deval test, commonly used in other states, to evaluate the durability of Alaskan aggregates in AC pavement as well as its potential to replace Washington degradation test. Micro-Deval test, Washington degradation test and other tests currently specified in Alaska were conducted on aggregates from 16 batches representing statewide sources. Based on the testing results, it is found that using Micro-Deval test for durability assessment of Alaska aggregates was feasible and reproducible, and a high potential was revealed to use Micro-Deval test to replace Washington degradation test in Alaska. It is recommended that Micro-Deval test be considered as an additional test for a certain period, but in the long run should be used along with current LA abrasion and sulfate soundness tests to provide a more desirable durability assessment of Alaska aggregates used in AC pavement.

关键词： aggregate durability Washington degradation test Micro-Deval test

An Optimal Feed Interpolator Based on G^2 Continuous Bézier Curves for High-Speed Machining of Linear Tool Path

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Chinese Journal of Mechanical Engineering 2019年第3期32卷 109-118页

作者： Yongqiao Jin sheng zhao Yuhan Wang Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tangency and curvature, huge number of line segments, and short lengths of line segments. These disadvantages hinder the development of high speed machining. To smooth the linear tool path and improve machining efficiency of short line segments, this paper presents an optimal feed interpolator based on G^2 continuous Bézier curves for the linear tool path. First, the areas suitable for fitting are screened out based on the geometric characteristics of continuous short segments (CSSs). CSSs in every area are compressed and fitted into a G^2 Continuous Bézier curve by using the least square method. Then a series of cubic Bézier curves are generated. However, the junction between adjacent Bézier curves is only G^0 continuous. By adjusting the control points and inserting Bézier transition curves between adjacent Bézier curves, the G^2 continuous tool path is constructed. The fitting error is estimated by the second-order Taylor formula. Without iteration, the fitting algorithm can be implemented in real-time environment. Second, the optimal feed interpolator considering the comprehensive constraints (such as the chord error constraint, the maximum normal acceleration, servo capacity of each axis, etc.) is proposed. Simulation and experiment are conducted. The results shows that the proposed method can generate smooth path, decrease the amount of segments and reduce machining time for machining of linear tool path. The proposed research provides an effective method for high-speed machining of complex 2-D/3-D profiles described by short line segments.

关键词： G^2 continuous path Least square method High-speed machining Continuous short segments Optimal feed interpolator Data compression

Ordered Reproducing Hilbert Spaces over C^2

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Acta Mathematica Sinica,English Series 2008年第3期24卷 503-510页

作者： sheng zhao HOU Jie WANG Department of Mathematics Suzhou University Suzhou 215006 P R China Department of Mathematics Shanxi Normal University Linfen 041004 P. R. China

In this paper, we study the relation between the ordered reproducing Hilbert space and its reproducing kernel. A complete description of a similar and unitary equivalence of two quasi-invariant subspaces generated by ... 详细信息

关键词： ordered reproducing Hilbert spaces quasi-invariant subspaces

Triplet management for room-temperature continuous-wave perovskite lasers

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Science China Chemistry 2021年第1期64卷 1-2页

作者： Haiyun Dong Yong-sheng zhao Key Laboratory of Photochemistry Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

Over the past sixty years,lasers have undergone substantial developments and have revolutionized sciences,technologies,and *** particular,the invention of compact semiconductor lasers has made this technology an integral part of everyday *** halide perovskites have recently emerged as an outstanding class of semiconductors holding great potentials in further advancing the laser technology[1].

关键词： everyday perovskite sixty

Effect of Microdomain Structure on the Mechanical Behavior of Binary Blends

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Chinese Journal of Polymer Science 2015年第7期33卷 964-975页

作者： Bin Su Yong-sheng zhao 陈枫傅强 College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan University

The relationship between microphase structure and mechanical response of the binary blends consisting of polystyrene-block-polyisoprene-block-polystyrene copolymer and low molecular weight polystyrene has been investigated. Low molecular weight polystyrene was chosen to obtain uniformly solubilized nano-blends without macrophase separation. The specimens were solution-cast by adding different amounts of homo-polystyrene to acquire different microphase structures. Small angle X-ray scattering（SAXS）, transmission electron microscopy（TEM） and atom force microscopy（AFM） have been used to study the microdomain and grain structure. It is observed that the structural changes in d-spacing and grain size on account of different amounts of polystyrene alter the mechanical behavior in both monotonic tensile and cyclic tests. The elastic and the Mullins effects are strongly sensitive to the changes in d-spacing and grain sizes. Moreover, the sample with bi-continuous structure shows the largest tensile strength and Mullins effect. In addition, the Mooneye-Rivlin phenomenological model was used to evaluate and explore the relationship between the polymer topological networks and the rubber elasticity of these styrenic nano-blends.

关键词： Microphase Grain size d-Spacing Bi-continuous structure Elastic response

Identification of maca(Lepidium meyenii Walp.) and its adulterants by a DNA-barcoding approach based on the ITS sequence

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Chinese Journal of Natural Medicines 2015年第9期13卷 653-659页

作者： CHEN Jin-Jin zhao Qing-sheng LIU Yi-Lan ZHA sheng-Hua zhao Bing National Key Laboratory of Biochemical Engineering Institute of Process Engineering Chinese Academy of Sciences University of Chinese Academy of Sciences Beijing Tong Ren Tang Health Pharmaceutical Co. Ltd.

Maca(Lepidium meyenii) is an herbaceous plant that grows in high plateaus and has been used as both food and folk medicine for centuries because of its benefits to human health. In the present study, ITS(internal transcribed spacer) sequences of forty-three maca samples, collected from different regions or vendors, were amplified and analyzed. The ITS sequences of nineteen potential adulterants of maca were also collected and analyzed. The results indicated that the ITS sequence of maca was consistent in all samples and unique when compared with its adulterants. Therefore, this DNA-barcoding approach based on the ITS sequence can be used for the molecular identification of maca and its adulterants.

关键词： Lepidium meyenii Maca ITS DNA-barcoding Molecular identification

Analysis and Optimization of a Spatial Parallel Mechanism for a New 5-DOF Hybrid Serial-Parallel Manipulator

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Chinese Journal of Mechanical Engineering 2018年第3期31卷 60-68页

作者： Dong-sheng Zhang Yun-Dou Xu Jian-Tao Yao Yong-sheng zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University

Hybrid manipulators have potentially application in machining industries and attract extensive attention from many researchers on the basis of high sti ness and high dexterity. Therefore,in order to expand the application prospects of hybrid manipulator,a novel 5?degree?of?freedom(DOF) hybrid serial?parallel manipulator(HSPM) is proposed. Firstly,the design plan of this manipulator is introduced. Secondly,the analysis of this manipulator is carried out in detail,including kinematics analysis,statics analysis,and workspace analysis. Especially,an amplitude equivalent method of disposing the over?constrained force/couple to the non?overconstrained force/couple is used in the statics analysis. Then,three performance indices are used to optimize the PM. Two of them have been widely used,and the third one is a new index which considers the characteristics of the actuated force. Based on the performance indices,the performance atlas is drawn and the optimal design of the PM is investigated. In order to satisfy the anticipant kinetic characteristics of the PM,the verification of the optimized physical dimension is done and the workspace based on the optimized physical dimension is carried out. This paper will lay good theoretical foundations for application of this novel HSPM and also can be applied to other hybrid manipulators.

关键词： Parallel mechanism Performance indices Optimal design Performance atlas