Time-limited pest control of a Lotka–Volterra model with impulsive harvest

A kind of time-limited pest control of a Lotka–Volterra model with impulsive harvest, described by the initial and boundary value problem of impulsive differential equation, is presented. The aim of pest control can be achieved if the model has a solution, otherwise the aim cannot be achieved. By the comparison principle, the conditions under which the model has a solution are found by a series of the upper solutions and the conditions under which the model has no solution are also given by a series of the lower solutions. Furthermore, if the other parameters are given, the times of harvesting pest in the given time is estimated. The theoretical results and the numerical simulations show that the density of the natural enemy will decrease when the pest decreases although the control measures to the pest do not directly affect the natural enemy. Finally, some discussions are given.     

Uniqueness Questions for Some Classes of Haar Series

Sets of relative uniqueness for Haar series are studied. Whole classes of conditions on the behavior of a Haar series, including the Arutyunyan--Talalyan condition, are considered. New numerical characteristic of perfect sets are introduced. They are used to obtain necessary conditions and sufficient conditions for a given set to be a set of relative uniqueness under certain assumptions. Thereby, the 1967 results of G. M. Mushegyan are generalized. Moreover, for 0<p<2, the existence of perfect U-sets with the G(p)-conditions introduced by W. Wade in 1981 is proved and a method for constructing such sets is given.     

Construction and optimization of predictions on the basis of first-degree recurrence splines

The problem of point and interval predictions of time series on the basis of first-degree recurrence splines with depth 1 is investigated. Optimality conditions for the coefficients of the calculation formula are found. Results of numerical experiments for analytically given functions with errors are presented. A comparison with classical methods of prediction of time series is given.     

Nonparametric orthogonal series estimators of regression: A class attaining the optimal convergence rate in L2

In this note a class of nonparametric orthogonal series type estimators for regression function fitting is considered. Sufficient conditions are given for the estimators to attain the optimal convergence rate in the mean integrated square error sense. Using results from the theory of numerical integration, examples of estimators are given, for which the above mentioned conditions hold.     

Fourier series representation of the coupler curves of spatial linkages

In this paper, the three-dimensional Fourier series which can describe the coupler curves of spatial linkages are derived. Based on the geometric properties of one-dimensional and two-dimensional Fourier series, a geometric constraint conditions are proposed to establish the three-dimensional Fourier series. The geometric meaning of mechanism for the three-dimensional Fourier series is put forward. Finally, an example is given to show the feasibility and the validity of this approach.     

On Fourier Re-Expansions

An old problem on absolute convergence of the re-expansion in the sine (cosine) Fourier series of an absolutely convergent cosine (sine) Fourier series is extended to the non-periodic case (Fourier transforms). Necessary and sufficient conditions are given as relations between the Fourier transforms and their Hilbert transforms. Sufficient conditions for integrability of the Hilbert transform are obtained.     

Salem’s Conditions in the Nonperiodic Case

Salem’s necessary conditions for a trigonometric series to be the Fourier series of an integrable function are generalized to the nonperiodic case for functions in the Wiener algebra. Applications of the obtained result are given.     

The central limit theorem for lacunary series

In this paper, the central limit theorem for lacunary trigonometric series is proved. Two gap conditions by Erdos and Takahashi are extended and unified. The criterion for the Fourier character of lacunary series is also given.

     

An Exponential Inequality for U-Statistics Under Mixing Conditions

The family of U-statistics plays a fundamental role in statistics. This paper proves a novel exponential inequality for U-statistics under the time series setting. Explicit mixing conditions are given for guaranteeing fast convergence, the bound proves to be analogous to the one under independence, and extension to non-stationary time series is straightforward. The proof relies on a novel decomposition of U-statistics via exploiting the temporal correlatedness structure. Such results are of interest in many fields where high-dimensional time series data are present. In particular, applications to high-dimensional time series inference are discussed.     

A Topological Ivasev-Musatov Theorem

If the sum of a series of positive numbers is not convergentand the series satisfies certain regularity conditions, a probabilitymeasure can be found whose support contains no interval, yetwhose Fourier series decreases faster than the given series.     

Towards Nikishin’s theorem on the almost sure convergence of rearrangements of functional series

Necessary and sufficient conditions are found for the almost sure convergence of almost all simple rearrangements of a series of Banach space valued random variables. The results go back to Nikishin’s well-known theorem on the existence of an almost surely convergent rearrangement of a numerical random series. An example is also given of a numerical random series with general term tending to zero almost surely such that this series converges in probability and any its rearrangement diverges almost surely.     

Series solutions for Laplace''s equation with nonhomogeneous mixed boundary conditions and irregular boundaries

Series solutions to Laplace's equation provide accurate analytical results for problems with regular boundary geometries. This paper develops the series approach, providing a solution methodology for problems with nonhomogeneous, mixed boundary conditions, defined on irregular boundaries. The series coefficients are obtained by first transforming to Poisson's equation with some homogeneous boundary conditions, and then modifying the eigenfunction expansion theory to cater for irregular boundary geometry. The computational details for evaluating the series coefficients are given, and the method demonstrated by a practical example.     

On examples concerning integrability theorems for trigonometric series

Examples of trigonometric series are constructed that are not Fourier series, with coefficients whose differences are majorized by an arbitrary sequence of numbers given in advance, which satisfies certain natural conditions.     

Feasibility of time-limited control of a competition system with impulsive harvest

A kind of time-limited control model on a competition system with impulsive harvest, described by impulsive differential equation with the initial and boundary value problem, is presented. The existence of solution of the model, corresponding to the feasibility of the short-term control, is discussed. By the comparison principle, the conditions under which the model has a solution are found by a series of the upper solutions, and the conditions under which the model has no solution are also given by a series of the lower solutions. Finally, the practical meanings of those conditions are explained. As an example, if other parameters are given, the times of the impulsive control is estimated and the theoretical results are verified by numerical simulations.     

Sulla convergenza delle serie reali a termini non negativi

In this paper some necessary and sufficient conditions are given for convergence of a series with non-negative terms. As a particular case, one finds again the well-known ratio-test for convergence of series with positive terms; in such a connection, some observations are made of didactical interest. Finally, some relations are emphasiged concerning theorems of convergence for real series (here obtained) and fixed point theorems already known.     

Conditions for strong Morita equivalence of partially ordered semigroups

We investigate when a partially ordered semigroup (with various types of local units) is strongly Morita equivalent to a posemigroup from a given class of partially ordered semigroups. Necessary and sufficient conditions for such equivalence are obtained for a series of well-known classes of posemigroups. A number of sufficient conditions for several classes of naturally ordered posemigroups are also provided.     

BCH-代数的原子与分支

在BCH—代数中引入了原子与分支的概念，给出了一个元素为BCH-代数原子的一系列等价条件，证明了一个BCH—代数的所有原子作成的集合是一个广义结合BCI—代数，最后对BCH—代数分支的性质进行了讨论。     

关于独立场合重对数律的收敛速度

本文证明(1)收敛的一些充要条件,并给出重对数律收(?)速度的一种描述.全文假定随机变量序列{X_n,n≥1}独立,但不必同分布,EX_j=0,EX_j~2=σ_j~2,     

Some applications of an integral transform

A representation for an absolutely convergent series of real numbers is given. A necessary and sufficient condition for the (Lebesgue) summability of a function and conditions for the summability of the intermediate derivatives of a function are presented.     

数列极限迫敛性定理的推广(英文)

极限论是微积分中基础和重要的概念.数列极限的迫敛性定理既能判断数列的收敛性,也给出其极限值。通过对数列极限迫敛性定理的条件加以改进,得到了它的推论,并用一个例子说明了该推论的应用。