检索结果-南通市图书馆

One-step estimation for varying coefficient models

在线全文

学校读者我要写书评

暂无评论

science china Mathematics 2005年第2期48卷 198-213页

作者： TANG Qingguo & WANG Jinde department of Mathematics, nanjing university, nanjing 2.0093. china Institute of {3.s, PLA university of {3. and Technology, nanjing 210007, china department of Mathematics Nanjing University Nanjing China Institute of sciences PLA University of Science and Technology Nanjing China

A one-step method is proposed to estimate the unknown functions in the varying coefficient models, in which the unknown functions admit different degrees of smoothness. In this method polynomials of different orders are used to approximate unknown functions with different degrees of smoothness. As only one minimization operation is employed, the required computation burden is much less than that required by the existing two-step estimation method. It is shown that the one-step estimators also achieve the optimal convergence rate. Moreover this property is obtained under conditions milder than that imposed in the two-step estimation method. More importantly, as only one minimization operation is employed, the full asymptotic properties, not only the asymptotic bias and variance, but also the asymptotic distributions of the estimators can be derived. The asymptotic distribution results will play a key role for making statistical inference.

关键词： varying coefficient model, one-step estimation, asymptotic distribution, optimal convergence rate.

Effects　of　copper，manganese　and　pH　on　the　growth　and　several　enzyme　activities　of　mycorrhizal　fungus　Cenococcum　geophilum　Fr．

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 1996年第4期8卷 419-425页

作者： Kong Fanxiang Zhang Min(department of Environmental science and engineering,{3.,nanjing 2.0093.china) department of Environmental science Nanjing University Nanjing 210093 China

he effects of various concentrations of copper,manganese and ph on the growth,protein content and several enzyme activities of mycorrhizal fungus Cenococcum geophilum Fr. Were *** results showed that high concentration of copper (20 mg/L)and low ph (3.0-4.0) inhibited the mycelial growth (dry weight), however, the protein content increased or not significantly reduced in mycelia after copper or manganese was applied. The activities of acid phosphatase and α-mannosidase were induced by high concentration of Mn (200-400 mg/L);but the activities of G6PDH, MTLDH and trehalase were inhibited by high content of copper(10-20 mg/L),both of the responses of these enzymes and mycelial growth under the presence of copper were correlative each other. Measurement of these enzyme activities might therefore provide a useful criterion for the evaluation of the fungitoxicity of soil contaminated by copper.

关键词： copper manganese ph mycorrhizal fungus enzyme activity.

Extraction of the spectral information of terahertz signals using superconducting Josephson junction

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2010年第5期53卷 1247-1251页

作者： XU WeiWei,CHEN Jian,KANG Lin & WU PeiHeng department of Electronic science & engineering,{3. university,{3. 2.0093.china department of Electronic science & engineering Nanjing University Nanjing China

Using YBa2Cu3.7-δ/MgO bicrystal Josephson junction,we have developed a setup for spectrum analyses of terahertz signals,up to 2.5 THz,with a frequency resolution of 3.*** junction works at liquid nitrogen temperature when the signal frequencies are low while for signals at 1.6 THz and 2.5 THz the junction is cooled to 6 *** signal processing(DSP) chips are made use of to build a data acquisition and processing system so that it can be compact,fast,and *** the completion of the relevant hardwares and softwares,the measurements are now automated.

关键词： Josephson junction THz wave spectrum detection DSP technology

A relative local variational principle for topological pressure

在线全文

学校读者我要写书评

暂无评论

science china Mathematics 2010年第6期53卷 1491-1506页

作者： MA XianFeng1,CHEN ErCai2,3.& ZHANG AiHua2,4 1department of Mathematics,East china university of {3. and Technology,Shanghai 20023.,china 2School of Mathematics and Computer {3.,nanjing Normal university,nanjing 210097,china 3.enter of Nonlinear {3.,nanjing university,nanjing 2.0093.china 4College of Mathematics and Physics,nanjing university of Posts and Telecommunications,nanjing 210046,china department of Mathematics East China University of Science and Technology Shanghai China School of Mathematics and Computer science Nanjing Normal University Nanjing China Center of Nonlinear science Nanjing University Nanjing China College of Mathematics and Physics Nanjing University of Posts and Telecommunications Nanjing China

We define the relative local topological pressure for any given factor map and open cover,and prove the relative local variational principle of this *** precisely,for a given factor map π:(X,T)→(Y,S) between two topological dynamical systems,an open cover U of X,a continuous,real-valued function f on X and an S-invariant measure ν on Y,we show that the corresponding relative local pressure P(T,f,U,y) satisfies sup μ∈M(X,T){ hμ(T,U|Y)+∫X f(x)dμ(x) :πμ=ν}=∫Y P(T,f,U,y)dν(y),where M(X,T) denotes the family of all T-invariant measures on ***,the supremum can be attained by a T-invariant measure.

关键词： pressure conditional entropy relative local variational principle

GLOBAL CONVERGENCE AND IMPLEMENTATION OF NGTN METHOD FOR SOLVING LARGE-SCALE SMARSE NONLINEAR PROGRAMMING PROBLEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2001年第4期19卷 337-346页

作者： Qin Ni (department of Mathematics, nanjing university of Aeronautics and Astronautics, nanjing 210016, {3.) 南京航空航天大学江苏南京 210016

An NGTN method was proposed for solving large-scale sparse nonlinear programming (NLP) problems. This is a hybrid method of a truncated Newton direction and a modified negative gradient direction, which is suitable for handling sparse data structure and pos sesses Q-quadratic convergence rate. The global convergence of this new method is proved, the convergence rate is further analysed, and the detailed implementation is discussed in this paper. Some numerical tests for solving truss optimization and large sparse problems are reported. The theoretical and numerical results show that the new method is efficient for solving large-scale sparse NLP problems.

关键词： Nonlinear programming Large-scale problem Sparse.

Thermal Insulation and Strength of Autoclaved Light Concrete

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(Materials science) 2011年第1期26卷 132-136页

作者：杨若冲吴智深 School of Transportation Southeast University Institute of Urban engineering science & Technology Southeast University

The primary objective of this study was to develop an autoclaved light concrete （ALC） material with ultra-thermal insulation property and to investigate the relationship between its physical characteristics and mechanical properties. Through tests of dry bulk density and compressive strength, relationship of physical characteristics and mechanical properties of samples were studied, resulting in a material with ultra-thermal insulation property. Scanning electron microscope （SEM） and energy-dispersive X-ray spectroscopy （EDX） were applied to analyze the micro-morphology and elemental composition of samples. To identify the product phases, X-ray diffraction （XRD） was engaged. The test results showed that compressive strength and thermal coefficient were reduced with the increasing of aluminum powder within the mixtures. As a result the optimal thermal coefficient and compressive strength of samples were improved to 0.061 W/（m·k） and 1.2 MPa, respectively. SEM, EDX and XRD analyses showed that calcium silicate hydrate and tobermorite crystal were main resultant phases.

关键词： autoclaved light concrete ultra-thermal insulation microscopic appearance and phase analysis tobermorite crystal

A new method for imaging faint objects nearby a bright source

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 2000年第3期45卷 201-207页

作者： YE Binxun & CHU Yi1. Beijing Astronomical Observatory, Chinese Academy of sciences, Beijing 100012, china 2. NAOCAS, Beijing 100012, china 3. {3. of Astronomy, nanjing university, nanjing china Correspondence should be addressed to Ye Binxun Beijing Astronomical Observatory Chinese Academy of Sciences Beijing China NAOCAS Beijing China department of Astronomy Nanjing University Nanjing China

In astronomical observation, it is difficult to obtain the image of faint objects in the peripheral area around a bright celestial body. in order to solve the problem, a new method is designed and experimented, which is called the separation readout technique (SRT). SRT is different from either the traditional coronagraphy or the newly-developed anti-blooming CCD technique, and allows an enough-long exposure to the faint objects in the area around a bright celestial body with the well-preserved bright body’s image in one frame. This paper describes in detail the principle of SRT, the computer simulation, the experimental devising and result of SRT observation on a telescope.

关键词： astronomyical methods CCD imaging SRT.

Prolonged exposure to resistin inhibits glucose uptake in rat skeletal muscles

在线全文

学校读者我要写书评

暂无评论

Acta Pharmacologica Sinica 2007年第3期28卷 410-416页

作者： Hong-qi FAN~(2,3. Nan GU~(2,3. Feng LIU~2 Li EEI~2 Xiao-qin PAN~2 Mei GUO~2 Rong-hua CHEN~(2,4) Xi-rong GUO~(2,3.4)2 department of Pediatrics,nanjing Maternal and Child Health Hospital of nanjing Medical {3.,nanjing 210004,china 3.Institute of Pediatrics Medicine,nanjing Medical {3.,nanjing 210029,china department of Pediatrics Nanjing Maternal and Child Health Hospital of Nanjing Medical University Nanjing China Institute of Pediatrics Medicine Nanjing Medical University Nanjing China

Aim:To assess the effects and mechanisms of the action of resistin on basal andinsulin-stimulated glucose uptake in rat skeletal muscle ***:Rat myo-blasts（L6）were cultured and differentiated into myotubes followed by stimula-tion with single commercial resistin（13. ng/mL,0-24 h）or cultured supernatantfrom 293.T cells transfected with resistin-expressing vectors（13. ng/mL,0-24 h）.Liquid scintillation counting was used to quantitate[3.]2-deoxyglucose *** translocation of insulin-sensitive glucose transporters GLUT4 and GLUT1,synaptosomal-associated protein 23.SNAP23.and GLUT protein content,as wellas the tyrosine phosphorylation status and protein content of insulin receptorsubstrate（IRS）-1,were assessed by Western ***:Treatment of L6myotubes with single resistin or cultured supernatant containing recombinantresistin reduced basal and insulin-stimulated 2-deoxyglucose uptake and impairedinsulin-stimulated GLUT4 *** SNAP23.protein content wasdecreased,no effects were noted in GLUT4 or GLUT1 protein *** diminished insulin-stimulated IRS-1 tyrosine phosphorylation levels withoutaffecting its protein *** effects of recombinant resistin from 293.T cellstransfected with resistin-expressing vectors were greater than that of single ***:Resistin regulated IRS-1 function and decreased GLUT4translocation and glucose uptake in response to *** downregulatedexpression of SNAP23.may have been partly attributed to the decrease of glucoseuptake by resistin *** observations highlight the potential role ofresistin in the pathophysiology of type 2 diabetes related to obesity.

关键词： resistin insulin glucose uptake obesity diabetes

Three-dimensional elasticity solution of simple-supported rectangular plate on point supports, line supports and elastic foundation

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(Technological sciences) 2009年第3期52卷 584-589页

作者： XU YePeng1 & ZHOU Ding2 1 School of science, nanjing university of science and Technology, {3. 210094, china 2 College of Civil engineering, nanjing university of Technology, {3. 210009, china School of science Nanjing University of Science and Technology Nanjing China College of Civil engineering Nanjing University of Technology Nanjing China

This paper studies the bending of simple-supported rectangular plate on point supports, line supports and elastic foundation. On the basis of three-dimensional elasticity theory, the exact expressions of the displacement functions, which satisfy the governing differential equations and the simply supported boundary conditions at four edges of the plate, are analytically derived. The reaction forces of the in- termediate supports are regarded as the unknown external forces acting on the lower surface of the plate. The unknown coefficients are then determined by the boundary conditions on the upper and lower surfaces of the plate. Comparing the numerical results obtained from the proposed method to those obtained from Kirchhoff plate theory, Mindlin plate theory and those obtained from the commer- cial finite element software ANSYS, the high accuracy of the present method has been demonstrated.

关键词： rectangular plate point support line support elastic foundation displacement stress three-dimensional elasticity solution