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Efficient estimation for additive hazards regression with bivariate current status data

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Science china Mathematics 2012年第4期55卷 763-774页

作者： TONG XingWei 1,,HU Tao 2.& SUN JianGuo 3,4 1 school of mathematical Sciences,Beijing Normal {2.,Beijing 100875,china 2.school of mathematical Sciences,Capital Normal {2.,Beijing 100048,china 3.school of Mathematics,Jilin {2.,Changchun 130012.china 4 Department of Statistics,{2. of Missouri,Columbia,MO 652.1,USA school of mathematical Sciences Beijing Normal University Beijing China school of mathematical Sciences Capital Normal University Beijing China school of Mathematics Jilin University Changchun China Department of Statistics University of Missouri Columbia USA

This paper discusses efficient estimation for the additive hazards regression model when only bivariate current status data are available. Current status data occur in many fields including demographical studies and tumorigenicity experiments （Keiding, 1991; Sun, 2.06） and several approaches have been proposed for the additive hazards model with univariate current status data （Linet M., 1998; Martinussen and Scheike, 2.02.. For bivariate data, in addition to facing the same problems as those with univariate data, one needs to deal with the association or correlation between two related failure time variables of interest. For this, we employ the copula model and an efficient estimation procedure is developed for inference. Simulation studies are performed to evaluate the proposed estimates and suggest that the approach works well in practical situations. An illustrative example is provided.

关键词： bivariate current status data copula model counting processes efficient estimation joint survivalfunction

Thermodynamic Analysis of the Preparation Process of EB-PVD SiC Coating

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Journal of Wuhan university of Technology(Materials Science) 2009年第3期24卷 363-366页

作者：易剑 school of Mechatronics Engineering Taizhou University Laser Processing Center Tianjin Polytechnic University Center for Composite Materials Harbin Institute of Technology

The process of preparing SiC coating by electron beam-physical vapor deposition （EB-PVD） was discussed from viewpoint of thermodynamis. Results show that within the temperature range of 2.700-3 300 K, the ratio of SiC in the SiC coating doesn＇t change much and keeps around 0.7. Purity of the as-deposited SiC coating is not high. To improve the purity of the SiC coating, the SiC ingot is required to not be, necessary in full density but be fine-grained.

关键词： thermodynamics SiC coating EB-PVD ratio of SiC purity

Power functions with low uniformity on odd characteristic finite fields

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Science china Mathematics 2010年第8期53卷 1931-1940页

作者： ZHA ZhengBang 1,3 & WANG XueLi 2.1 school of mathematical Sciences,Luoyang Normal {2.,Luoyang 47102.,china 2.school of mathematical Sciences,South china Normal {2.,Guangzhou 510631,china 3 State Key Laboratory of Information Security,Graduate {2. of Chinese Academy of Sciences,Beijing 100049,china school of mathematical Sciences Luoyang Normal University Luoyang China State Key Laboratory of Information Security Graduate University of Chinese Academy of Sciences Beijing China school of mathematical Sciences South China Normal University Guangzhou China

In this paper,we give some new low differential uniformity of some power functions defined on finite fields with odd *** corollaries of the uniformity,we obtain two families of almost perfect nonlinear functions in GF... 详细信息

关键词： almost perfect nonlinear function differential uniform function finite field

On the composition operators on the Bloch space of several complex variables

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Science china Mathematics 2005年第Z1期48卷 392-399页

作者： ZHOU Zehua & CHE Renyu Department of Mathematics, tianjin university, tianjin 300072. china LiuHui Center for Applied Mathematics, nankai university & tianjin university,tianjin 300072. china Department of Mathematics Tianjin University Tianjin China LiuHui Center for Applied Mathematics Nankai University & Tianjin University Tianjin China

In this paper we first look upon some known results on the composition operator as bounded or compact on the Bloch-type space in polydisk and ball, and then give a sufficient and necessary condition for the compositio... 详细信息

关键词： Bloch space, bounded symmetric domains, composition operator, bergman metric.

Influence of moisture content and time on the mechanical behavior of polymer material

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Science china(Technological Sciences) 2004年第5期47卷 595-607页

作者： ZHENG Gaofei1, 2. KANG Yilan1, SHENG Jing3, QIN Qinghua1, WANG Huaiwen1 & FU Donghui1 1. Department of Mechanics, tianjin university, tianjin 300072. china 2. Department of Mechanics, tianjin Polytechnic university, tianjin 300160, china 3. Department of Material Engineering, tianjin university, tianjin 300072. china Correspondence should be addressed to Kang Yilan Department of Mechanics Tianjin University Tianjin China Department of Mechanics Tianjin Polytechnic University Tianjin China Department of Material Engineering Tianjin University Tianjin China

The effects of moisture content and time on mechanical behavior of polymer materials are investigated both theoretically and experimentally in this paper. An equivalence relationship between time intervals and the moisture content for polymer nylon-6 has been established by way of experimental observation and measured results. The relationship shows that there exists equivalence between moisture and service time in affecting mechanical properties. In other words, an increase in moisture can be replaced by prolonging acting time in producing the same effect on material properties. Consequently, a moisture-time superposition principle is presented based on the experimental results and the analogy of temperature-time superposition principle. Numerical results such as stress-strain curves with different moisture contents are presented to verify the applicability and correctness. The proposed method appears very promising in study on the effect of moisture content on mechanical behavior of polymer materials.

关键词： equivalence relationship of moisture-time, moisture content, mechanical properties, shift function.

Finite time extinction of super-Brownian motions with deterministic catalyst

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Science china Mathematics 2003年第4期46卷 538-551页

作者：任艳霞王永进 LMAM School of Mathematical Sciences Peking University Beijing 100871China school of Mathematics Nankai UniversityTianjin 300071 China

In this paper we consider a super-Brownian motion X with branching mechanism k(x)z α, where k(x) > 0 is a bounded H?lder continuous function on ?d and ${}_{{}_x \in \mathbb{R}^d }k(x) = 0$ . We prove that ifk(x)?‖x‖?l (0?l2.and d ≥ 3: it isO(‖x‖?(α+1)) in one dimension,O(‖x‖?2.log ‖x‖))?(α+1)) in two dimensions, andO(‖x‖2. in higher dimensions. These growth orders also turn out to be the maximum order for the nonexistence of a positive solution for 1/2.u=k(x)u α.

关键词： super-Brownian motion, compact support property, finite time extinction, positive solutions to nonlinear pde's.

Uniqueness and local stability for the inverse scattering problem of determining the cavity

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Science china Mathematics 2005年第8期48卷 1113-1123页

作者： FENG Lixin & MA Fuming LMAM, school of mathematical Sciences, Peking {2., Beijing 100871, china school of mathematical Sciences, Heilongjiang {2., Harbin 150080, china school of mathematical Sciences, Jilin {2., Changchun 130012. china LMAM School of Mathematical Sciences Peking University Beijing China school of mathematical Sciences Heilongjiang University Harbin China school of mathematical Sciences Jilin University Changchun China

Considering a time-harmonic electromagnetic plane wave incident on an arbitrarily shaped open cavity embedded in infinite ground plane, the physical process is modelled by Maxwell's equations. We investigate the inverse problem of determining the shape of the open cavity from the information of the measured scattered field. Results on the uniqueness and the local stability of the inverse problem in the 2.dimensional TM (transverse magnetic) polarization are proved in this paper.

关键词： uniqueness, stability, Maxwell's equations, inverse scattering problem.

Transitional function of DG to CA3 in the hippocampus

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Progress in Natural Science:Materials International 2007年第12期17卷 1436-1444页

作者： Yan Chuankui1 and Liu Shenquan2.1. Department of Mathematics, Hangzhou Normal university, Hangzhou 310036, china 2. Department of Applied Mathematics, {2. of mathematical Sciences, South china university of Technology, Guangzhou 510640, china) Department of Mathematics Hangzhou Normal University Hangzhou 310036 China Department of Applied Mathematics School of Mathematical Sciences South China University of Technology Guangzhou 510640 China

Using single cell channel model, the transmission features of CA3-DG network in the hippocampus are investigated. The influence of the stimulation on discharge pattern of pyramidal neurons is analyzed, which shows that it starts with period spiking discharges, followed by period-doubling bifurcation to chaos, and period 3 discharge evolving into chaos, and ultimately a period of bursting discharges. By the synaptic model, the CA3-DG network model is constructed, which analyzes the summation of postsynaptic currents in the network, the influence of postsynaptic current on discharge rhythm as well as the mechanism of bursting discharges. The strong capacity of spatiotemporal encoding in the network indicates the features of CA3 network during the information transmission process in the hippocampus. The modeling result with time delay of the synaptic transmission is in accordance with the experimental phenomena of action potential in the hippocampus.

关键词： hippocampus CA3-DG period-doubling bifurcation chaos.

Homotopy type of smooth weighted complete intersections

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Science china Mathematics 2010年第6期53卷 1583-1594页

作者： WANG JianBo1,& WANG YuYu2.1Department of Mathematics,tianjin university,tianjin 300072.china 2.ollege of mathematical Science,tianjin Normal university,tianjin 300387,china Department of Mathematics Tianjin University Tianjin China College of mathematical Science Tianjin Normal University Tianjin China

If the total degree d has no prime divisors less than(n+3)/2.then we prove that the homotopy type of complex odd dimensional smooth weighted complete intersection Xn(d;w) is determined by the dimension n,the total degree d,the Euler characteristic and the Kervaire invariant,provided that the weights w =(ω0,...,ωn+r) is pairwise relatively prime.

关键词： weighted projective space weighted complete intersection homotopy type connected sum