检索结果-南通市图书馆

Complete hypersurfaces in a 4-dimensional hyperbolic space

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2009年第3期24卷 370-378页

作者： XU Hong-wei1 ZHAO En-tao2 center of Mathematical Sciences,zhejiang University,hangzhou 310027,china center of Mathematical Sciences Zhejiang University Hangzhou China

This paper gives a classification of complete hypersurfaces with nonzero constant mean curvature and constant quasi-Gauss-Kronecker curvature in the hyperbolic space H4（-1）,whose scalar curvature is bounded from below.

关键词： complete hypersurface mean curvature quasi-Gauss-Kronecker curvature

The first eigenvalue of Laplace operator under powers of mean curvature flow

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第7期53卷 1702-1709页

作者： ZHAO Liang center of Mathematical Sciences, zhejiang University, hangzhou 310027, china center of Mathematical Sciences Zhejiang University Hangzhou China

In this paper, we derive the evolution equation for the first eigenvalue of Laplace operator along powers of mean curvature flow. Considering a compact, strictly convex n-dimensional surface M without boundary, which is smoothly immersed in R n+1 , we prove that if the initial 2-dimensional surface M is totally umbilical, then the first eigenvalue is nondecreasing along the unnormalized H k -flow. Moreover, as applications of the evolution equation, we construct some monotonic quantities along this kind of flow.

关键词： Laplace operator H k -flow eigenvalue monotonicity

General expansion for period maps of Riemann surfaces

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第8期53卷 2021-2030页

作者： YIN FangLiang center of Mathematical Sciences,zhejiang University,hangzhou 310027,china center of Mathematical Sciences Zhejiang University Hangzhou China

In this paper,we get the full expansion for period map from the moduli space Mg of curves to the coarse moduli space Ag of g-dimensional principally polarized abelian varieties in Bers *** generalizes fully the famous Rauch's variational *** applications,we compute the curvature of Siegel metric at point [X] with Π([X]) =√ -1 Ig and the Christoffel symbols of L2-induced Bergman metric on Mg.

关键词： period map moduli space Siegel metric Bergman metric

TRIPLE　INTERACTIONS　OF　CONORMAL　WAVES　FOR　HIGHER　ORDER　SEMILINEAR　HYPERBOLIC　EQUMIONS

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 1995年第1期16卷 23-32页

作者： FANG DAOYUAN (center for Mathematical Sciences, zhejiang University, hangzhou 310027, china.) 浙江大学数学科学中心浙江杭州

The interaction of three conormal waves for semi-linear strictly hyperbolic equations of third order is considered. Let Σi, i = 1, 2, 3, be smooth characteristic surfaces for P= Da(D_t￣2 -△) intersecting transversally at the origin. Suppose that the solution u to Pu = f(t, x ,y)D u), ≤2 is conormal to Σi, i = 1, 2, 3, for t 2, 3.

关键词： Hyperbolic equation Conormal wave Interaction Characteristic surface.

Quasi-static Analysis of Thrust-loaded Angular Contact Ball Bearings Part Ⅱ:Results and Discussion

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第1期25卷 81-87页

作者： CHEN Wenhua1,2,MA Zikui1,GAO Liang1,LI Xinglin3,and PAN Jun2 1 Institute of Mechanical Design,zhejiang University,hangzhou 310027,china 2 Institute of Mechanical Design and Manufacturing,zhejiang Sci-Tech University,hangzhou 310018,china 3 State Testing Laboratory of hangzhou Bearing Test & Research center,hangzhou 310022,china Institute of Mechanical Design Zhejiang University Hangzhou China Institute of Mechanical Design and Manufacturing Zhejiang Sci-Tech University Hangzhou China State Testing Laboratory of hangzhou Bearing Test & Research center Hangzhou China

Ball bearings are widely employed mechanical components characterized by high precision and quality,and usually play important roles in various rotary machines and *** advanced applications require a deep understanding of their various kinematic and tribological characteristics that are essential to predict the fatigue endurance,relieve the vibration and minimize the power dissipation of ball bearings in particular *** angular contact ball bearing under a specified operating condition is simulated with the quasi-static/creepage analytical model proposed in the preceding *** results demonstrate that the ball bearing is a statically determinate *** the balls spin on both inner and outer races means the ball is controlled by neither the inner nor the outer *** friction between the ball and raceway renders the inner and outer contact angles *** larger the coefficient of friction is,the larger the angle *** tangential traction perpendicular to the rolling direction due to the spin induces a gyro-like rotation of the ball with respect to the raceway even if no inertial effects are *** tangential elastic compliance of contacting surfaces gives rise to locked areas within the contact patch and transforms the sliding lines from circles into *** differential slip due to the close conformity of the ball and raceway makes the sliding and traction distributions asymmetric,which will influence the location of the spinning center of the ball with respect to the *** quasi-static/creepage model can be used to reveal the operating behaviors of ball bearings running under steady conditions and to optimize the design of ball bearings for specific applications.

关键词： ball bearing quasi-static creepage differential slip tangential elastic compliance

Surface electromagnetic modes contribution to the anomalous terahertz transmission through double-layered metal hole array

在线全文

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第1期55卷 90-97页

作者： RAO Lei1&YANG DongXiao1,2 1Department of Information Science and Electronic Engineering,zhejiang University,hangzhou 310027,china 2Research center for Terahertz Technology,zhejiang University,hangzhou 310027,china Department of Information Science and Electronic Engineering Zhejiang University Hangzhou China Research center for Terahertz Technology Zhejiang University Hangzhou China

Terahertz transmission spectra through both single-layered and double-layered sub-wavelength metal hole arrays were calculated using rigorous mode-matching *** dispersion relations of the single-layered and double-layered metal hole arrays were obtained by FDTD *** are three anomalous peaks in the spectrum of the double-layered metal hole array,which arise from the three surface electromagnetic modes appearing in the dispersion *** comparing the transmission spectra and the dispersion relations of the single-layered and double-layered metal hole arrays,it was found that the two surface electromagnetic modes at higher frequencies are introduced by the single-layered metal hole array,while the one at lower frequencies is introduced by the double-layered metal hole *** validity of the analysis was qualitatively verified by the experimental *** structure can be finely designed for potential applications,such as wideband filtering.

关键词： surface electromagnetic modes double-layered metal hole array terahertz

Photosynthetically active radiation retrieval based on HJ-1A/B satellite data

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china Earth Sciences 2010年第S1期53卷 81-91页

作者： LI Li1,XIN XiaoZhou1,SU GaoLi1,2 & LIU QinHuo1 1 State Key Laboratory of Remote Sensing Science,Institute of Remote Sensing Applications,Chinese Academy of Sciences,Beijing 100101,china 2.zhejiang climate center,hangzhou 3.0017,china State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing China zhejiang climate center Hangzhou China

Photosynthetically active radiation(PAR) is essential for plant photosynthesis and carbon cycle,and is also important for meteorological and environmental *** advance china's disaster and environmental monitoring capabilities,the HJ-1A/B satellites have been placed in Earth *** of their environmental monitoring objectives is the study of *** simulated direct solar,scattered and environment radiation between 400 and 700 nm under different atmospheric parameters(solar zenith angle,atmospheric water vapor,atmospheric ozone,aerosol optical thickness,surface elevation and surface albedo),and then established a look-up table between these input parameters and *** on the look-up table,we used HJ-1A/B aerosol and surface albedo outputs to derive the corresponding *** of inversed instantaneous and observed PAR values using HJ-1 Heihe experimental data had a root mean square error of 25.2 W m-2,with a relative error of 5.9%.The root mean square error for accumulated daily PAR and observed values was 0.49 MJ m-2,with a relative error of 3.5%.Our approach improved significantly the computational efficiency,compared with using directly radiation transfer *** also studied the sensitivity of various input parameters to photosynthetically active radiation,and found that solar zenith angle and atmospheric aerosols were sensitive PAR *** albedo had some effect on PAR,but water vapor and ozone had minimal impact on PAR.

关键词： Photosynthetically active radiation 6S HJ-1A/B satellites

Predictor-based error correction method in short-term climate prediction

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2008年第1期18卷 129-135页

作者： Hongli Ren Laboratory for climate Studies,National climate center,china Meteorological Administration,Beijing 100081,china Laboratory for climate Studies National Climate Center China Meteorological Administration Beijing 100081 China

In terms of the basic idea of combining dynamical and statistical methods in short-term climate prediction,a new prediction method of predictor-based error correction(PREC)is put forward in order to effectively use statistical experiences in dynamical ***- yses show that the PREC can reasonably utilize the significant correlations between predictors and model prediction errors and correct prediction errors by establishing statistical prediction ***,the PREC is further applied to the cross-validation experiments of dynamical seasonal prediction on the operational atmosphere-ocean coupled general circulation model of china Meteorological Admin- istration/National climate center by selecting the sea surface temperature index in Ninflo3 region as the physical predictor that represents the prevailing ENSO-cycle mode of interannual variability in climate *** is shown from the prediction results of summer mean circulation and total precipitation that the PREC can improve predictive skills to some *** the PREC provides a new approach for improving short-term climate prediction.

关键词： Short-term climate prediction Seasonal prediction Predictor Error correction

The three-dimensional structure of Infectious flacherie virus capsid determined by cryo-electron microscopy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Life Sciences) 2009年第12期52卷 1186-1191页

作者： XIE Li1,4, ZHANG QinFen2·, LU XingMeng3, DAI XinHong2, LI KunPeng2, HONG Jian1,4· & ZHOU XuePing11 Institute of Biotechnology, zhejiang University, hangzhou 310029, china 2 State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, china 3 College of Animal Sciences, zhejiang University, hangzhou 310029, china 4 center of Analysis and Measurement, zhejiang University, hangzhou 310029, china Institute of Biotechnology Zhejiang University Hangzhou China center of Analysis and Measurement Zhejiang University Hangzhou China State Key Laboratory of Biocontrol School of Life Sciences Sun Yat-Sen University Guangzhou China College of Animal Sciences Zhejiang University Hangzhou China

Cryo-electron microscopy and image reconstruction were used to determine the three-dimensional structure of Infectious flacherie virus (IFV). 5047 particles were selected for the final reconstruction. The FSC curve showed that the resolution of this capsid structure was 18 ·. The structure is a psuedo T=3 (P=3) icosahedral capsid with a diameter of 302.4 · and a single shell thickness of 15 ·. The density map showed that IFV has a smooth surface without any prominent protrude or depression. Comparison of the IFV structure with those of the insect picorna-like virus-Cricket paralysis virus (CrPV)and human picornavirus-Human rhinovirus 14 (HRV 14) revealed that the IFV structure resembles the CrPV structure. The "Rossmann canyon" is absent in both IFV and CrPV particles. The polypeptide topology of IFV VP2, IFV VP3 was predicted and the subunit location at the capsid surface was further analyzed.

关键词： Infectious flacherie virus cryo-electron microscopy three-dimensional structure polypeptide folding