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Numerical investigation of turbulent flow coherent structures in annular jet pumps using the LES method

Science China(Technological Sciences) 2018年第1期61卷 86-97页

作者： XU MaoSen YANG XueLong LONG XinPing LYU q.ao ji Bin Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan University Wuhan 430072 China School of Power and Mechanical Engineering Wuhan University Wuhan 430072 China Research Institute of Nuclear Power Operation Wuhan 430074 China

Annular jet pumps that are used in hydraulic machinery have a very simple structure but very complex internal flow fields. Large eddy simulations were used to study the coherent structures in the turbulent flows in annular jet pumps with various area ratios,m. The distribution, movement and evolution of the coherent structure in the annular jet pumps are described based on vorticity,pressure and q.criteria. All the criteria demonstrate that the vortexes are mainly distributed in the recirculation region and in the mixing and the boundary layers, which have large velocity gradients. The various characteristics of the coherent structures are shown by the different criteria with the vorticity criterion describing the distribution, movement and evolution of the vortexes,the pressure criterion describing the movement and the q.criterion describing the vortex movement and evolution. The vorticity variation in the spanwise direction is larger than the variation in the streamwise direction; however, the streamwise vortex is the main mechanism driving the entrainment of the secondary flow and the mixing. The annular jet pump with m=3.33 had a higher vortex shedding freq.ency(about 1000 Hz) than that with m=1.72(313–417 Hz). The azimuthal instability is the main reason for the generation of the streamwise vortex from the spanwise vortex. The vortex structures in the recirculation region are very strong,but small and disordered with no periodic vortex rings.

关键词： annular jet pump coherent structure large eddy simulation turbulent flow

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Differential Operator Approach to■q.antum Groups and Their Oscillator Representations

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1360-1374页

作者： Zhao Bing FAN ji Cheng GENG Shao Long HAN College of Mathematical Science Harbin Engineering UniversityHarbin 150001P.R.China

For a q.asi-split Satake diagram,we define a modified q.Weyl algebra,and show that there is an algebra homomorphism between it and the corresponding■q.antum *** other words,we provide a differential operator approach to■q.antum ***,the oscillator representations of■q.antum groups are *** crystal basis of the irreducible subrepresentations of these oscillator representations are constructed.

关键词： ■q.antum group differential operator oscillator representation crystal basis

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Far-field super-resolution chemical microscopy

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Light(Science & Applications) 2023年第7期12卷 1246-1267页

作者： Mingwei Tang Yubing Han Danchen jia q.ng Yang ji-Xin Cheng State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China Intelligent Perception Research Institute Zhejiang LabHangzhou 311100China Department of Biomedical Engineering Department of Electrical and Computer EngineeringPhotonics CenterBoston UniversityBostonMA 02459USA

Far-feld chemical microscopy providing molecular electronic or vibrational fingerprint information opens a new window for the study of three-dimensional biological,material,and chemical *** microscopy provides a nondestructive way of chemical identification without exterior ***,the diffraction limit of optics hindered it from discovering more details under the resolution *** development of super-resolution techniq.es gives enlightenment to open this door behind far-field chemical ***,we review recent advances that have pushed the boundary of far-field chemical microscopy in terms of spatial *** further highlight applications in biomedical research,material characterization,environmental study,cultural heritage conservation,and integrated chip inspection.

关键词： chemical details optics

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A Common Generalization to Theorems on Set Systems with L-intersections

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Acta Mathematica Sinica,English Series 2018年第7期34卷 1087-1100页

作者： jiu q.ang LIU Sheng Gui ZHANG ji Meng XIAO School of Management Engineering Xi'an University of Finance and Economics Xi'an 710100 P. R. China Department of Mathematics Eastern Michigan University Ypsilanti MI 48197 USA Department of Mathematics Northwestern Polytechnical University Xi'an 710072 P. R. China

In this paper, we provide a common generalization to the well-known Erdos-Ko-Rado Theorem, Frankl-Wilson Theorem, Alon-Babai-Suzuki Theorem, and Snevily Theorem on set systems with L-intersections. As a conseq.ence, we derive a result which strengthens substantially the well- known theorem on set systems with k-wise E-intersections by Furedi and Sudakov [J. Combin. Theory, Set. A, 105, 143-159 （2004）]. We will also derive similar results on E-intersecting families of subspaces of an n-dimensional vector space over a finite field Fq. where q.is a prime power.

关键词： Alon-Babai-Suzuki Theorem Erdos-Ko-Rado Theorem Frankl-Wilson Theorem Snevily Theorem multilinear polynomials

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ON RUBIN'S HARMONIC ANALYSIS AND ITS RELATED POSITIVE DEFINITE FUNCTIONS

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Acta Mathematica Scientia 2012年第5期32卷 1851-1874页

作者： Nji Bettaibi Kamel Mezlini Moufida El Gunichi College of Science Qassim UniversityBuridaKingdom of Saudi Arabia Institute Suprieur des Sciences Appliq.es et de la Technologie de Mateur Route de TabarkaMateur7030Tunisia Facult des Sciences de Tunis Campus Universitaire TunisEl Manar2092 TunisTunisia

In this paper,a new formulation of the Rubin’s q.translation is given,which leads to a reliable q.harmonic ***,related q.positive definite functions are introduced and studied,and a Bochner’s theorem is proved.

关键词： q.harmonic analysis definite positive function Bochner theorem

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Automorphisms of Extensions of q.by a Direct Sum of Finitely Many Copies of q

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Acta Mathematica Sinica,English Series 2019年第2期35卷 204-212页

作者： He Guo LIU Yu Lei WANG ji Ping ZHANG Department of Mathematics Hubei University Department of Mathematics He'nan University of Technology The School of Mathematical Sciences Peking University

Let G be an extension of q.by a direct sum of r copies of q.(1) If G is abelian, then G is a direct sum of r + 1 copies of q.and Aut G = GL(r + 1, q.;(2) If G is non-abelian, then G is a direct product of an extraspecial q.group E and m copies of q. where E/ζ E is a linear space over q.with dimension 2 n and m + 2 n = r. Furthermore, let Aut_G'G be the normal subgroup of Aut G consisting of all elements of Aut G which act trivially on the derived subgroup G of G, and Aut_(G/ζG),_(ζG)G be the normal subgroup of Aut G consisting of all central automorphisms of G which also act trivially on the center ζ G of G. Then(i) The extension 1→ Aut_(G')G→ Aut G→ Aut G'→ 1 is split;(ii)Aut_(G')G/Aut_(G/ζG),_(ζG)G = Sp(2 n, q. ×(GL(m, q. q.(m));(iii) Aut_(G/ζG),ζGG/Inn G= q.(2 nm).

关键词： Extraspecial q.group group extension symplectic group automorphism group

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A Classification of Spectrum-determined Circulant Digraphs

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Acta Mathematicae Applicatae Sinica 2018年第4期34卷 703-709页

作者： Zheng-xin q.N ji-xiang MENG q.ong-xiang HUANG School of Mathematics and Information Technology Jiangsu Second Normal University Nanjing 210013 China Department of Mathematics Xinjiang University Urumuqi 830054 China

Some researchers have proved that Adam＇s conjecture is wrong. However, under special conditions,it is right. Let Zn be a cyclic group of order n and Cn（S） be the circulant digraph of Zn with respect to S？Zn／q.. In the literature, some people have used a spectral method to solve the isomorphism for the circulants of prime-power order. In this paper, we also use the spectral method to characterize the circulants of order paq.ωc（where p,q.and ω are all distinct primes）, and to make Adam＇s conjecture right.

关键词： Circulant digraph Isomorphism Spectrum Cyclotomic polynomial

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Hydrogen isotopes in palmitic and stearic acids in suspended particles from the Changjiang River Estuary

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Science China Earth Sciences 2016年第2期59卷 981-988页

作者： XING Lei Julian P.SACHS ZHANG HaiLong LI Li ji Zhongq.ang ZHAO MeiXun Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education Ocean University of China Qingdao 266100 China q.ngdao Collaborative Innovation Center of Marine Science and Technology Qingdao 266100 China School of Oceanography University of Washington Seattle WA 98195 USA State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration Hangzhou 310012 China

Hydrogen isotopes in lipid biomarkers can trace past changes in the hydrologic cycle. Recent studies have revealed the potential of hydrogen isotopes in microalgal lipids for q.antitatively reconstructing water δ~2H（δD） values and salinity. In this study we collected suspended particles along a salinity gradient from the Changjiang River Estuary（CRE）, and measured δD values in fatty acids in these particles. The results indicated that δD values of water were correlated highly with salinity from the CRE, in agreement with the results from other estuaries. δD values in palmitic acid and stearic acid had a positive correlation with δD values of water from the CRE. Nevertheless, in the CRE, hydrogen isotope fractionation in fatty acids relative to water increased as salinity increased, opposite the trend in hydrogen isotope fractionation with salinity found in microalgal culture and field studies. We attribute the increase in hydrogen isotope fractionation as salinity increased to light availability, which was likely lower in the particle rich mixing zone at the end of the estuary, and potentially as well to multiple sources of fatty acids in the CRE.

关键词： Hydrogen isotope Palmitic acid Stearic acid Changjiang river estuary Salinity

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Design and simulation of a tuning fork micromachined gyroscope with slide film damping

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光学精密工程 2005年第5期13卷 519-524页

作者： CHE Lu-feng XIONG Bin jiAO ji-wei WANG Yue-lin State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

A novel tuning fork micromachined gyroscope, based on slide-film damping, is presented. The electrostatic driving gyroscope consists of two driving masses each of which supports one sensitive mass. The angular rate is sensed by the differential capacitances consisted of movable bar electrodes and fixed bar electrodes located on the glass wafer. The gyroscope can operate at atmospheric pressure with slide film damping in the driving and sensing directions, eliminate vacuum packaging and restrain cross-axis acceleration signal. The results of design and simulation show that the driving and sensing mode freq.encies are 3 106 Hz and 3 175 Hz,respectively, and the q.values in driving and sensitive modes are 1 721 and 1 450 respectively. The design resolution is 0.025°/s.

关键词：等效电路模拟角度传感器微电子力学系统电路等效方程

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A novel method for telescope polarization modeling based on an artificial neural network

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Research in Astronomy and Astrophysics 2021年第7期21卷 41-50页

作者： jian-Guo Peng Shu Yuan Kai-Fan ji Zhi Xu Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China

The polarization characteristics of an astronomical telescope is an important factor that affects polarimetry accuracy. Polarization modeling is an essential means to achieve high precision and efficient polarization measurement of the telescope, especially for the alt-azimuth mount telescope. At present, the polarization model for the telescope(i.e., the physical parametric model) is mainly constructed using the polarization parameters of each optical element. In this paper, an artificial neural network(ANN) is used to model the polarization characteristics of the telescope. The ANN model between the physical parametric model residual and the pointing direction of the telescope is obtained, which reduces the model deviation caused by the incompleteness of the physical parametric model. Compared with the physical parametric model, the model fitting and predictive accuracy of the New Vacuum Solar Telescope(NVST) is improved after adopting the ANN model. After using the ANN model, the polarization cross-talk from I to q. U, and V can be reduced from 0.011 to 0.007, and the crosstalk among q. U, and V can be reduced from 0.047 to 0.020, which effectively improves the polarization measurement accuracy of the telescope.

关键词： techniq.es:polarimetric telescopes polarization instrumentation:polarimeters

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