共查询到20条相似文献,搜索用时 142 毫秒
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运用脉冲时滞微分方程的比较理论,频闪映射和一些分析方法,讨论了一类捕食者具有脉冲扩散、食饵具有阶段结构的捕食-食饵模型得到了成熟食饵灭绝周期解的全局吸引和系统持久的充分条件,证明了系统的所有解是一致完全有界的.最后通过举例并进行数值模拟说明所得结果的正确性. 相似文献
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《应用泛函分析学报》2019,(2)
通过使用叠合度理论中的Mawhin连续定理和不等式技巧,分析带有收获项和脉冲的时滞食饵捕食系统的动态特征,从而,获得带有收获项和脉冲的时滞食饵捕食系统至少存在八个正概周期解的充分条件. 相似文献
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连续收获捕食者与脉冲存放食饵的阶段结构捕食-食饵模型的全局吸引和一致持久 总被引:2,自引:1,他引:1
研究了一个捕食者具连续收获与食饵具脉冲存放的阶段结构时滞捕食-食饵模型.根据生物资源管理的实际,改进了捕食者具阶段结构的捕食-食饵模型,即原来假设每个捕食者个体都具有相同的捕食食饵的能力.假设捕食者按年龄分为两个阶段,即幼体和成体,而且幼体无能力捕食食饵.得到了捕食者灭绝周期解全局吸引和系统持久的充分条件.结论说明了脉冲存放食饵对系统的持久起了重要的作用,并且为生物资源管理提供了策略基础.数值分析也进一步说明了系统的动力学性质. 相似文献
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讨论了与可再生生物资源管理相关的食饵具脉冲扰动与捕食者具连续收获的阶段结构时滞捕食-食饵模型,得到了捕食者灭绝周期解的全局吸引和系统持久的充分条件.也证明了系统的所有解的一致完全有界.结论为现实的可再生生物资源管理提供了可靠的策略依据. 相似文献
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讨论了与害虫治理相关的一类捕食者具脉冲扰动与食饵具有化学控制的阶段结构时滞捕食-食饵模型,得到了害虫灭绝周期解的全局吸引和系统持久的充分条件,也证明了系统的所有解的一致完全有界.得出的结论为现实的害虫治理提供了可靠的策略依据. 相似文献
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该文研究一类带有中立型脉冲时滞和Holling-Ⅳ型功能反应函数的捕食-食饵模型.通过运用Mawhin迭合度理论和分析技巧,得到了捕食-食饵模型正周期解存在性的充分条件. 相似文献
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H. Mohebi A. M. Rubinov 《分析论及其应用》2006,22(1):20-40
We develop a theory of downward sets for a class of normed ordered spaces. We study best approximation in a normed ordered space X by elements of downward sets, and give necessary and sufficient conditions for any element of best approximation by a closed downward subset of X. We also characterize strictly downward subsets of X, and prove that a downward subset of X is strictly downward if and only if each its boundary point is Chebyshev. The results obtained are used for examination of some Chebyshev pairs (W,x), where ∈ X and W is a closed downward subset of X 相似文献
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It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary. 相似文献
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J. C. Ponce Campuzano 《International Journal of Mathematical Education in Science & Technology》2019,50(7):999-1010
ABSTRACTUndergraduate students usually study Laurent series in a standard course of Complex Analysis. One of the major applications of Laurent series is the classification of isolated singular points of complex functions. Although students are able to find series representations of functions, they may struggle to understand the meaning of the behaviour of the function near isolated singularities. In this paper, I briefly describe the method of domain colouring to create enhanced phase portraits to visualize and study isolated singularities of complex functions. Ultimately this method for plotting complex functions might help to enhance students' insight, in the spirit of learning by experimentation. By analysing the representations of singularities and the behaviour of the functions near their singularities, students can make conjectures and test them mathematically, which can help to create significant connections between visual representations, algebraic calculations and abstract mathematical concepts. 相似文献
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Using actions of free monoids and free associative algebras, we establish some Schreier-type formulas involving ranks of actions and ranks of subactions in free actions or Grassmann-type relations for the ranks of intersections of subactions of free actions. The coset action of the free group is used to establish a generalization of the Schreier formula in the case of subgroups of infinite index. We also study and apply large modules over free associative and free group algebras. 相似文献
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Stephen Dias Barreto 《Proceedings Mathematical Sciences》2000,110(4):347-356
We study a quantum spin glass as a quantum spin system with random interactions and establish the existence of a family of
evolution groups {τt(ω)}ω∈/Ω of the spin system. The notion of ergodicity of a measure preserving group of automorphisms of the probability space Ω, is
used to prove the almost sure independence of the Arveson spectrum Sp(τ(ω)) of τt(ε). As a consequence, for any family of (τ(ω),β) — KMS states {ρ(ω)}, the spectrum of the generator of the group of unitaries
which implement τ(ω) in the GNS representation is also almost surely independent of ω. 相似文献
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B. Harlamov 《Acta Appl Math》2003,78(1-3):165-174
The property of absolute continuity of measures in the class of one-dimensional semi-Markov processes of diffusion type is investigated. The measure of such a process can be composed of two measures. The first one is a distribution of a random track, and the second one is a conditional distribution of a time run along the track. The desired density is represented in the form of product of two corresponding densities. 相似文献
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Yew-Kwang Ng 《Mathematical Social Sciences》1980,1(1):51-68
After noting factors (concern for others, ignorance, irrationality) accounting for the divergences between preference and happiness, the question of representing the preference of an individual by a utility function is discussed, taking account of lexicographic ordering, imperfect discrimination and the corresponding concepts of semiorder and sub-semiorder. Methods to improve upon the interpersonal comparability of measures of happiness such as pinning down the dividing line of zero happiness and the use of a just perceivable increment of happiness are discussed. The relation of social welfare to individual welfare (i.e. happiness) is then considered. Some reasonable set of axioms ensuring that social welfare is a separable function of and indeed an unweighted sum of individual welfares are reviewed. Finally, happiness is regarded as a function of objective, institutional and subjective factors; an interdisciplinary approach is needed even for an incomplete analysis. 相似文献
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A rigid isotopy of nonsingular real algebraic curves on a quadric is a path in the space of such curves of a given bidegree.
We obtain the rigid isotopy classification of nonsingular real algebraic curves of bidegree (3, 3) on a hyperboloid and on
an ellipsoid. We also study of the space of real algebraic curves of bidegree (3, 3) with a single node or cusp.
Translated fromMatematicheskie Zametki, Vol. 66, No. 6, pp. 810–815, December, 1999. 相似文献
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We combine aspects of the theory of motives in algebraic geometry with noncommutative geometry and the classification of factors to obtain a cohomological interpretation of the spectral realization of zeros of L-functions. The analogue in characteristic zero of the action of the Frobenius on ?-adic cohomology is the action of the scaling group on the cyclic homology of the cokernel (in a suitable category of motives) of a restriction map of noncommutative spaces. The latter is obtained through the thermodynamics of the quantum statistical system associated to an endomotive (a noncommutative generalization of Artin motives). Semigroups of endomorphisms of algebraic varieties give rise canonically to such endomotives, with an action of the absolute Galois group. The semigroup of endomorphisms of the multiplicative group yields the Bost-Connes system, from which one obtains, through the above procedure, the desired cohomological interpretation of the zeros of the Riemann zeta function. In the last section we also give a Lefschetz formula for the archimedean local L-factors of arithmetic varieties. 相似文献
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V. P. Stavrov V. V. Stavrov N. V. Pankova K. Friedrich 《Mechanics of Composite Materials》2000,36(2):155-162
The influence of displacements of tensioned fibers on the impregnation of fibrous layers with a polymer melt and on the final
composite structure is studied. Using computer simulation, it is shown that, during impregnation, the structure of tensioned
fibrous layers changes considerably depending on the initial arrangement and tensioning of fibers. The consolidated regions
formed under the melt front move inside the impregnated layer with the advancing melt front. Displacement of the tensioned
fibers as well as the formation of “washouts” favors the impregnation of internal layers, but cause significant inhomogeneity
of the polymer structure. The surface (on the side of the melt flow) regions are more saturated with the polymer than the
internal ones. A difference in the melt percolation mechanisms at various impregnation regimes is revealed. The effective
permeability coefficients of a tensioned fiber layer are not constant but depend on the conditions and regimes of impregnation.
Submitted to the 11th Conference on the Mechanics of Composite Materials (Riga, June 11–15, 2000).
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 259–270, March–April, 2000. 相似文献