共查询到20条相似文献,搜索用时 218 毫秒
1.
2.
3.
4.
5.
This paper aims at providing an alternative approach to study global dynamic properties for a two-species chemotaxis model, with the main novelty being that both populations mutually compete with the other on account of the Lotka–Volterra dynamics. More precisely, we consider the following Neumann initial–boundary value problem in a bounded domain , with smooth boundary, where are positive constants.When and , it is shown that under some explicit largeness assumptions on the logistic growth coefficients and , the corresponding Neumann initial–boundary value problem possesses a unique global bounded solution which moreover approaches a unique positive homogeneous steady state of above system in the large time limit. The respective decay rate of this convergence is shown to be exponential.When and , if is suitable large, for all sufficiently regular nonnegative initial data and with and , the globally bounded solution of above system will stabilize toward as in algebraic. 相似文献
6.
7.
Aleksandar Ilić 《Computers & Mathematics with Applications》2010,59(8):2776-2783
Let be a simple undirected graph with the characteristic polynomial of its Laplacian matrix , . It is well known that for trees the Laplacian coefficient is equal to the Wiener index of , while is equal to the modified hyper-Wiener index of the graph. In this paper, we characterize -vertex trees with given matching number which simultaneously minimize all Laplacian coefficients. The extremal tree is a spur, obtained from the star graph with vertices by attaching a pendant edge to each of certain non-central vertices of . In particular, minimizes the Wiener index, the modified hyper-Wiener index and the recently introduced Incidence energy of trees, defined as , where are the eigenvalues of signless Laplacian matrix . We introduced a general transformation which decreases all Laplacian coefficients simultaneously. In conclusion, we illustrate on examples of Wiener index and Incidence energy that the opposite problem of simultaneously maximizing all Laplacian coefficients has no solution. 相似文献
8.
A well-known lemma of Suslin says that for a commutative ring if is unimodular where is monic and , then there exist such that the ideal generated by equals . This lemma played a central role in the resolution of Serre’s Conjecture. In the case where contains a set of cardinality greater than such that is invertible for each in , we prove that the can simply correspond to the elementary operations , , where . These efficient elementary operations enable us to give new and simple algorithms for reducing unimodular rows with entries in to using elementary operations in the case where is an infinite field. Another feature of this paper is that it shows that the concrete local–global principles can produce competitive complexity bounds. 相似文献
9.
10.
Francisco J. Solis Fausto Ongay Silvia Jerez Marcos Capistran 《Computers & Mathematics with Applications》2010,59(1):499-505
We define a family of discrete Advection–reaction operators, denoted by , which associate to a given scalar sequence the sequence given by , where for . For we explicitly find their iterates and study their convergence properties. Finally, we show the relationship between the family of discrete operators with the continuous one dimensional advection–reaction equation. 相似文献
11.
12.
13.
Josef Cibulka 《Theoretical computer science》2011,412(8-10):822-834
We are given a stack of pancakes of different sizes and the only allowed operation is to take several pancakes from the top and flip them. The unburnt version requires the pancakes to be sorted by their sizes at the end, while in the burnt version they additionally need to be oriented burnt-side down. We are interested in the largest value of the number of flips needed to sort a stack of pancakes, both in the unburnt version () and in the burnt version ().We present exact values of up to and of up to and disprove a conjecture of Cohen and Blum by showing that the burnt stack is not the hardest to sort for .We also show that sorting a random stack of unburnt pancakes can be done with at most flips on average. The average number of flips of the optimal algorithm for sorting stacks of burnt pancakes is shown to be between and and we conjecture that it is .Finally we show that sorting the stack needs at least flips, which slightly increases the lower bound on . This bound together with the upper bound for sorting found by Heydari and Sudborough in 1997 [10] gives the exact number of flips to sort it for and . 相似文献
14.
15.
16.
《Journal of Parallel and Distributed Computing》2004,64(11):1286-1296
In this paper, we investigate the star graph with faulty vertices and/or edges from the graph theoretic point of view. We show that between every pair of vertices with different colors in a bicoloring of , , there is a fault-free path of length at least , and there is a path of length at least joining a pair of vertices with the same color, when the number of faulty elements is or less. Here, is the number of faulty vertices. , , with at most faulty elements has a fault-free cycle of length at least unless the number of faulty elements are and all the faulty elements are edges incident to a common vertex. It is also shown that , , is strongly hamiltonian-laceable if the number of faulty elements is or less and the number of faulty vertices is one or less. 相似文献
17.
18.
Daewook Kim Jong Yeoul Park Yong Han Kang 《Computers & Mathematics with Applications》2018,75(9):3269-3282
In this paper, we show the energy decay rate for a von Karman system with a boundary nonlinear delay term. This work is devoted to investigate the influence of kernel function and the effect of the boundary nonlinear term , a boundary nonlinear time delay term and prove energy decay rates of solutions when do not necessarily decay exponentially and the boundary condition has a time delay. 相似文献
19.
Fenglong Sun Lishan Liu Yonghong Wu 《Computers & Mathematics with Applications》2018,75(10):3685-3701
In this paper, we study the initial boundary value problem for a class of parabolic or pseudo-parabolic equations: where , with being the principal eigenvalue for on and . By using the potential well method, Levine’s concavity method and some differential inequality techniques, we obtain the finite time blow-up results provided that the initial energy satisfies three conditions: (i) ; (ii) , where is a nonnegative constant; (iii) , where involves the -norm or -norm of the initial data. We also establish the lower and upper bounds for the blow-up time. In particular, we obtain the existence of certain solutions blowing up in finite time with initial data at the Nehari manifold or at arbitrary energy level. 相似文献
20.
Shuyan Qiu Chunlai Mu Liangchen Wang 《Computers & Mathematics with Applications》2018,75(9):3213-3223
This paper deals with the following quasilinear chemotaxis-growth system in a smoothly bounded domain under zero-flux boundary conditions. The parameters and are positive and the diffusion function is supposed to generalize the prototype with and . Under the assumption , it is proved that whenever , and , for any given nonnegative and suitably smooth initial data (, , ) satisfying , the corresponding initial–boundary problem possesses a unique global solution which is uniformly-in-time bounded. The novelty of the paper is that we use the boundedness of the with to estimate the boundedness of . Moreover, the result in this paper can be regarded as an extension of a previous consequence on global existence of solutions by Hu et al. (2016) under the condition that and . 相似文献