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In [1] a procedure for bias-free estimation of the autocorrelation function is introduced for equidistantly sampled data with randomly occurring samples being invalid. The method incorporates sample-and-hold interpolation of the missing data points. The occurring dynamic error of the primary estimate of the correlation function is treated by a deconvolution procedure with two parameters and with , which are the on-diagonal and the aside-diagonal parameters of a specific correction matrix (at all lag times except zero). The parameters and were obtained as a function of the probability α of a sample to be valid by numerical simulation. However, explicit expressions for the parameters and can be derived, which might improve the usability of the deconvolution procedure in [1]. 相似文献
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This paper deals with the spatial spreading speed and traveling wave solutions of a general epidemic model with nonlocal dispersal in time and space periodic habitats. It should be mentioned that the existence of spreading speed and traveling wave solutions of nonlocal dispersal cooperative system in space–time periodic habitats have been established previously. In this paper, we further show that the epidemic system has a spreading speed and for any , there exist a unique, continuous space–time periodic traveling wave solution of epidemic model in the direction of with speed , and there is no such solution for . 相似文献
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Urban Larsson Peter Hegarty Aviezri S. Fraenkel 《Theoretical computer science》2011,412(8-10):729-735
We prove a recent conjecture of Duchêne and Rigo, stating that every complementary pair of homogeneous Beatty sequences represents the solution to an invariant impartial game. Here invariance means that each available move in a game can be played anywhere inside the game board. In fact, we establish such a result for a wider class of pairs of complementary sequences, and in the process generalize the notion of a subtraction game. Given a pair of complementary sequences and of positive integers, we define a game by setting as invariant moves. We then introduce the invariant game , whose moves are all non-zero -positions of . Provided the set of non-zero -positions of equals , this is the desired invariant game. We give sufficient conditions on the initial pair of sequences for this ‘duality’ to hold. 相似文献
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Xue-hai Yuan Hong-xing Li E. Stanley Lee 《Computers & Mathematics with Applications》2010,59(9):3117-3129
In this paper, a new kind of intuitionistic fuzzy subgroup theory, which is different from that of Ma, Zhan and Davvaz (2008) [22], [23], is presented. First, based on the concept of cut sets on intuitionistic fuzzy sets, we establish the neighborhood relations between a fuzzy point and an intuitionistic fuzzy set . Then we give the definitions of the grades of belonging to , quasi-coincident with , belonging to and quasi-coincident with and belonging to or quasi-coincident with , respectively. Second, by applying the 3-valued Lukasiewicz implication, we give the definition of -intuitionistic fuzzy subgroups of a group for , and we show that, in 16 kinds of -intuitionistic fuzzy subgroups, the significant ones are the -intuitionistic fuzzy subgroup, the -intuitionistic fuzzy subgroup and the -intuitionistic fuzzy subgroup. We also show that is a -intuitionistic fuzzy subgroup of if and only if, for any , the cut set of is a 3-valued fuzzy subgroup of , and is a -intuitionistic fuzzy subgroup (or -intuitionistic fuzzy subgroup) of if and only if, for any (or for any ), the cut set of is a 3-valued fuzzy subgroup of . At last, we generalize the -intuitionistic fuzzy subgroup, -intuitionistic fuzzy subgroup and -intuitionistic fuzzy subgroup to intuitionistic fuzzy subgroups with thresholds, i.e., -intuitionistic fuzzy subgroups. We show that is a -intuitionistic fuzzy subgroup of if and only if, for any , the cut set of is a 3-valued fuzzy subgroup of . We also characterize the -intuitionistic fuzzy subgroup by the neighborhood relations between a fuzzy point and an intuitionistic fuzzy set . 相似文献
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The number of states in a deterministic finite automaton (DFA) recognizing the language , where is regular language recognized by an -state DFA, and is a constant, is shown to be at most and at least in the worst case, for every and for every alphabet of at least six letters. Thus, the state complexity of is . In the case the corresponding state complexity function for is determined as with the lower bound witnessed by automata over a four-letter alphabet. The nondeterministic state complexity of is demonstrated to be . This bound is shown to be tight over a two-letter alphabet. 相似文献
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We consider a micropolar fluid flow in a two-dimensional domain. We assume that the velocity field satisfies a non-linear slip boundary condition of friction type on a part of the boundary while the micro-rotation field satisfies non-homogeneous Dirichlet boundary conditions. We prove the existence and uniqueness of a solution. Then motivated by lubrication problems we assume that the thickness and the roughness of the domain are of order and we study the asymptotic behaviour of the flow as tends to zero. By using the two-scale convergence technique we derive the limit problem which is totally decoupled for the limit velocity and pressure on one hand and the limit micro-rotation on the other hand. Moreover we prove that , and are uniquely determined via auxiliary well-posed problems. 相似文献
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Amin Pourjabari Zanyar Esmailpoor Hajilak Alireza Mohammadi Mostafa Habibi Hamed Safarpour 《Computers & Mathematics with Applications》2019,77(10):2608-2626
This article investigates the influence of porosity on free and forced vibration characteristics of a nanoshell reinforced by graphene platelets (GPL). The material properties of piece-wise graphene-reinforced composites (GPLRCs) are assumed to be graded in the thickness direction of a cylindrical nanoshell and estimated using a nanomechanical model. In addition, because of imperfection of the current structure, three kinds of porosity distributions are considered. The nanostructure is modeled using modified strain gradient theory (MSGT) which is a size-dependent theory with three length scale parameters. The novelty of the current study is to consider the effects of porosity, GPLRC and MSGT on dynamic and static behaviors of the nanostructure. Considering three length scale parameters ( , , ) in MSGT leads to a better agreement with MD simulation in comparison by other theories. Finally, effects of different factors on static and dynamic behaviors of the porous nanostructure are examined in detail. 相似文献
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Mohamed Jleli Mokhtar Kirane Bessem Samet 《Computers & Mathematics with Applications》2019,77(3):740-751
We, first, consider the quantum version of the nonlinear Schrödinger equation where , is the principal value of , is the -derivative with respect to , is the Laplacian operator in , , , and is a complex-valued function. Sufficient conditions for the nonexistence of global weak solution to the considered equation are obtained under suitable initial data. Next, we study the system of nonlinear coupled equations
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《Computers & Mathematics with Applications》2007,53(7):1140-1152
We consider the time scale th-order differential operators and the higher-order dynamic equations We will show that these equations can be investigated as special cases of the so-called (delta or nabla) symplectic dynamic systems whose qualitative theory is well developed. We also suggest further perspectives of the investigation of the qualitative properties of higher-order equations with mixed derivatives. 相似文献
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In this paper, we prove a novel result of the consistency error estimate with order for
element (see Lemma 2) on anisotropic meshes. Then, a linearized fully discrete Galerkin finite element method (FEM) is studied for the time-fractional nonlinear parabolic problems, and the superclose and superconvergent estimates of order in broken -norm on anisotropic meshes are derived by using the proved character of element, which improve the results in the existing literature. Numerical results are provided to confirm the theoretical analysis. 相似文献
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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
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《Computers & Mathematics with Applications》2007,53(3-4):665-684