共查询到20条相似文献,搜索用时 15 毫秒
1.
LiJunYANG XianWuZENG 《数学学报(英文版)》2003,19(4):739-744
Two characterizations for a local diffeomorphism of R^n to be global one are given in terms of associated Wazewski equations.The two characterizations could be useful for the investigation of the Jacobian conjecture. 相似文献
2.
Abstract
With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, we study the global existence of
positive periodic solutions of a “food-limited population model with toxicants and time delays. Some new results are obtained.
Supported by the National Natural Sciences Foundation of China (No.10171010), the Key Project on Sciences and Technology of
the Ministry of Education of China (No. Key 01061) and the Natural Sciences Foundation for Young Scholar of Northeast Normal
University. 相似文献
3.
Xiao-nlng Lin Hong Wang Da-qing Jiang 《应用数学学报(英文版)》2007,23(2):289-302
This paper is devoted to the study ofthe existence of single and multiple positive solutions forthe first order boundary value problem x′= f(t,x),x(0)=x(T),where f ∈ C([0,T]×R).In addition,weapply our existence theorems to a class of nonlinear periodic boundary value problems with a singularity at theorigin.Our proofs are based on a fixed point theorem in cones.Our results improve some recent results in theliteratures. 相似文献
4.
In this paper we obtain local L
p
estimates for the parabolic polyharmonic equations by a straightforward approach.
Yao was supported by the Innovation Foundation of Shanghai University (Grant No. A10-0101-08-905), Shanghai Leading Academic
Discipline Project (Grant No. J50101) and Key Disciplines of Shanghai Municipality (Grant No. S30104). Zhou was supported
by the National Basic Research Program of China (Grant No. 2006CB705700), National Natural Science Foundation of China (Grant
No. 60532080), and the Key Project of Chinese Ministry of Education (Grant No. 306017) 相似文献
5.
Complexity of Reducing the Delay between Two Nodes by Node-based and Edge-based Upgrading Strategies
Xiao-guangYang Jian-zhongZhang 《应用数学学报(英文版)》2004,20(4):589-596
For a pair of nodes s, t in an undirected graph G = (V, A) and a given level U of allowable delay, we would like to modify the network by node-based or edge-based upgrading strategies to make the delay between s and t not greater than U. In this paper, we present some NP-hard results for the delay improvement problems. 相似文献
6.
In this paper, we get W
1,p
(R
n
)-boundedness for tangential maximal function and nontangential maximal function, which improves J.Kinnunen, P.Lindqvist and
Tananka’s results.
Supported by the key Academic Discipline of Zhejiang Province of China under Grant No.2005 and the Zhejiang Provincial Natural
Science Foundation of China. 相似文献
7.
Jin-bao Jian Ran Quan Qing-jie Hu 《应用数学学报(英文版)》2007,23(3):395-410
In this paper, the nonlinear minimax problems are discussed. By means of the Sequential Quadratic Programming (SQP), a new descent algorithm for solving the problems is presented. At each iteration of the proposed algorithm, a main search direction is obtained by solving a Quadratic Programming (QP) which always has a solution. In order to avoid the Maratos effect, a correction direction is obtained by updating the main direction with a simple explicit formula. Under mild conditions without the strict complementarity, the global and superlinear convergence of the algorithm can be obtained. Finally, some numerical experiments are reported. 相似文献
8.
Yong-ping Liu Gui-qiao XuDepartment of Mathematics Beijing Normal University Beijing China Department of Mathematics Tianjin Normal Univesity Tianjin . China 《应用数学学报(英文版)》2002,18(4):663-674
The classes of the multivariate functions with bounded moduli on Rd and Td are given and their average σ-widths and non-linear n-widths are discussed. The weak asymptotic behaviors are established for the corresponding quantities. 相似文献
9.
Ji-bin Li 《中国科学A辑(英文版)》2007,50(2):153-164
Using the methods of dynamical systems for the (n + 1)-dimensional multiple sine-Gordon equation, the existences of uncountably infinite many periodic wave solutions and breaking
bounded wave solutions are obtained. For the double sine-Gordon equation, the exact explicit parametric representations of
the bounded traveling solutions are given. To guarantee the existence of the above solutions, all parameter conditions are
determined.
This work was supported by the National Natural Science Foundation of China (Grant No. 11671179) and the Natural Science Foundation
of Yunnan Province (Grant No. 2005A0092M). 相似文献
10.
Guo Dong LIU Wen Peng ZHANG 《数学学报(英文版)》2008,24(2):343-352
The authors establish an explicit formula for the generalized Euler NumbersE2n^(x), and obtain some identities and congruences involving the higher'order Euler numbers, Stirling numbers, the central factorial numbers and the values of the Riemann zeta-function. 相似文献
11.
Multivariate failure time data arise frequently in survival analysis. A commonly used technique is the working independence
estimator for marginal hazard models. Two natural questions are how to improve the efficiency of the working independence
estimator and how to identify the situations under which such an estimator has high statistical efficiency. In this paper,
three weighted estimators are proposed based on three different optimal criteria in terms of the asymptotic covariance of
weighted estimators. Simplified close-form solutions are found, which always outperform the working independence estimator.
We also prove that the working independence estimator has high statistical efficiency, when asymptotic covariance of derivatives
of partial log-likelihood functions is nearly exchangeable or diagonal. Simulations are conducted to compare the performance
of the weighted estimator and working independence estimator. A data set from Busselton population health surveys is analyzed
using the proposed estimators.
This work was supported by National Natural Science Foundation of China (Grant No. 10628104), Fan was also supported by National
Institutes of Health (Grant No. R01-GM072611) and Natural Science Foundation (Grant No. DMS-0714554), Zhou was supported by
National Natural Science Funds for Distinguisheel Young Scholar (Grant No. 70825004), National Natural Science Foundation
of China (Grant Nos. 10731010, 10628104), the National Basic Research Program (Grant No. 2007CB814902), Creative Research
Groups of China (Grant No. 10721101) and Leading Academic Disipline Program, the 10
th
five year plan of 211 Project for Shanghai University of Finance and Economics (the 3
rd
phase), Cai was supported by National Institutes of Health (Grant No. R01-HL57444) 相似文献
12.
Long Jiang~ 《应用数学学报(英文版)》2004,20(3):507-512
It is proved that a probability measure is dominated by g-expectation ε_μ[·] if and only if it can begenerated by Girsanov transformation via a process which is uniformly bounded by μ. 相似文献
13.
Frame Wavelets with Compact Supports for L^2(R^n) 总被引:1,自引:0,他引:1
De Yun YANG King Wei ZHOU Zhu Zhi YUAN 《数学学报(英文版)》2007,23(2):349-356
The construction of frame wavelets with compact supports is a meaningful problem in wavelet analysis. In particular, it is a hard work to construct the frame wavelets with explicit analytic forms. For a given n × n real expansive matrix A, the frame-sets with respect to A are a family of sets in R^n. Based on the frame-sets, a class of high-dimensional frame wavelets with analytic forms are constructed, which can be non-bandlimited, or even compactly supported. As an application, the construction is illustrated by several examples, in which some new frame wavelets with compact supports are constructed. Moreover, since the main result of this paper is about general dilation matrices, in the examples we present a family of frame wavelets associated with some non-integer dilation matrices that is meaningful in computational geometry. 相似文献
14.
Blow Up of Solutions to Semilinear Wave Equations with Critical Exponent in High Dimensions 总被引:5,自引:2,他引:3 下载免费PDF全文
Yi ZHOU 《数学年刊B辑(英文版)》2007,28(2):205-212
In this paper, the author considers the Cauchy problem for semilinear wave equations with critical exponent in n≥4 space dimensions. Under some positivity conditions on the initial data, it is proved that there can be no global solutions no matter how small the initial data are. 相似文献
15.
Xiuqing Chen 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,60(3):416-437
We investigate the isentropic quantum drift-diffusion model, a fourth order parabolic system, in space dimensions d = 2, 3. First, we establish the global weak solutions with large initial value and periodic boundary conditions. Then we
show the semiclassical limit by delicate interpolation estimates and compactness argument.
Supported by the Natural Science Foundation of China (No.10401019 and No.10626030). 相似文献
16.
Hao YIN 《数学年刊B辑(英文版)》2006,27(4):401-410
Abstract
This paper deals with the periodic solutions of Schr?dinger flow from S
3 to S
2. It is shown that the periodic solution is related to the variation of some functional and there exist S1-invariant critical
points to this functional. The proof makes use of the Principle of Symmetric Criticality of Palais.
*Project supported by the National Natural Science Foundation of China (No.10321001). 相似文献
17.
LongJiang 《应用数学学报(英文版)》2004,20(4):701-706
With the help of a limit property of solutions of backward stochastic differential equations(BSDEs),this paper establishes a converse comparison theorem for deterministic generators g of BSDEs under the assumption g(t, y, 0) ≡0. 相似文献
18.
Shi Rong LI Xiu Yun GUO 《数学学报(英文版)》2007,23(4):731-734
A subgroup H of a finite group G is called a TI-subgroup if H ∩ H^x = 1 or H for all x ∈ G. In this paper, a complete classification for finite p-groups, in which all abelian subgroups are TI-subgroups, is given. 相似文献
19.
The Bott generator of the homotopy group π2k-1U(∞) is used to construct an almost complex structure on S6, which is integrable except a small neighborhood. 相似文献
20.
By variational methods, for a kind of Yamabe problem whose scalar curvature vanishes in the unit ball BN and on the boundary S^N-1 the mean curvature is prescribed, we construct multi-peak solutions whose maxima are located on the boundary as the parameter tends to 0^+ under certain assumptions. We also obtain the asymptotic behaviors of the solutions. 相似文献