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REGULAR SOLUTION OF THE INVERSE PROBLEM WITH INTEGRAL CONDITION FOR A TIME-FRACTIONAL EQUATION 具有积分条件的时间分数阶方程反问题的正则解
Pub Date : 1900-01-01 DOI: 10.31861/bmj2020.02.09
H. Lopushanska, A. Lopushansky
Direct and inverse problems for equations with fractional derivatives are arising in various fields of science and technology. The conditions for classical solvability of the Cauchy and boundary-value prob-lems for diffusion-wave equations with fractional derivatives are known. Estimates of components of the Green's vector-function of the Cauchy problem for such equations are known.We study the inverse problem of determining the space-dependent component of the right-hand side of the equation with a time fractional derivative and known functions from Schwartz-type space of smooth rapidly decreasing functions or with values in them. We also consider such a problem in the case of data from some wider space of smooth, decreasing to zero at infinity functions or with values in them.We find sufficient conditions for unique solvability of the inverse problem under the time-integral additional condition[frac{1}{T}int_{0}^{T}u(x,t)eta_1(t)dt=Phi_1(x), ;;;xin Bbb R^n]where $u$ is the unknown solution of the Cauchy problem, $eta_1$ and $Phi_1$ are the given functions.Using the method of the Green's vector function,we reduce the problem to solvability of an integrodifferential equation in a certain class of smooth, decreasing to zero at infinity functions. We prove its unique solvability.There are various methods for the approximate solution of direct and inverse problems for equations with fractional derivatives, mainly for the one-dimensional spatial case. It follows from our results the method of constructing an approximate solution of the inverse problem in the multidimensional spatial case. It is based on the use of known methods of constructing the numerical solutions of integrodifferential equations. The application of the Fourier transform by spatial variables is effective for constructing a numerical solution of the obtained integrodifferential equation, since the Fourier transform of the components of the Green's vector function can be explicitly written.
分数阶导数方程的正问题和反问题在科学技术的各个领域都有出现。已知具有分数阶导数的扩散波方程的柯西问题和边值问题的经典可解性条件。这类方程的柯西问题的格林矢量函数分量的估计是已知的。研究光滑速降函数或速降函数的schwartz型空间中具有时间分数阶导数和已知函数的方程右侧空间相关分量的反问题。我们也考虑了这样一个问题,当数据来自更宽的光滑空间,函数在无穷远处趋于零,或者其中有值。在时间积分附加条件[frac{1}{T}int_{0}^{T}u(x,t)eta_1(t)dt=Phi_1(x), ;;;xin Bbb R^n]下,得到了反问题唯一可解的充分条件,其中$u$为柯西问题的未知解,$eta_1$和$Phi_1$为给定函数。利用格林向量函数的方法,我们将问题简化为一类光滑的积分微分方程的可解性,在无穷远处降为零。证明了它的唯一可解性。分数阶导数方程的正反问题的近似解有多种方法,主要是一维空间情况。由此导出了多维空间情况下逆问题近似解的构造方法。它是基于使用已知的方法来构造积分微分方程的数值解。空间变量的傅里叶变换的应用对于构造得到的积分微分方程的数值解是有效的,因为格林向量函数的分量的傅里叶变换可以显式地表示出来。
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引用次数: 0
Optimal control in a nonlocal boundary value problem with integral conditions for parabolic equation with degeneration 带积分条件的退化抛物型方程非局部边值问题的最优控制
Pub Date : 1900-01-01 DOI: 10.31861/bmj2019.01.082
I. Pukal’skii, B. Yashan
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引用次数: 1
ON PROBLEMS FOR EIDELMAN TYPE EQUATIONS AND SYSTEM OF EQUATIONS 关于eidelman型方程和方程组的问题
Pub Date : 1900-01-01 DOI: 10.31861/bmj2022.02.17
N. Protsakh, H. Ivasiuk, T. Fratavchan
The problems for Eidelman type equations and systems of equations are considered in this paper. They were the large part of scientific interests for Prof. Ivasyshen S.D. The results of investigations of Cauchy problem, initial-boundary and the inverse problems for this type of equations in bounded or unbounded domains are given. The results are represented as the estimates of the solutions, the integral representations of solutions, theorems of the existence, uniqueness and stability of solutions.
本文研究了Eidelman型方程和方程组的问题。本文给出了这类方程在有界和无界域上的柯西问题、初边界问题和反问题的研究结果。结果被表示为解的估计、解的积分表示、解的存在性、唯一性和稳定性定理。
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引用次数: 0
WEAK R-SPACES AND UNIFORM LIMIT OF SEQUENCES OF THE FIRST BAIRE CLASS FUNCTIONS 一类函数序列的弱r空间与一致极限
Pub Date : 1900-01-01 DOI: 10.31861/bmj2019.02.039
Mykhaylo Lukan, O. Karlova
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引用次数: 0
ASYMPTOTIC BEHAVIOR OF THE LOGARITHMIC DERIVATIVE OF ENTIRE FUNCTION OF IMPROVED REGULAR GROWTH IN THE METRIC OF $L^q[0,2pi]$ L^q[0,2pi]度规上改进正则增长的整个函数的对数导数的渐近性质
Pub Date : 1900-01-01 DOI: 10.31861/bmj2021.01.04
R. Khats
Let $f$ be an entire function with $f(0)=1$, $(lambda_n)_{ninmathbb N}$ be the sequence of its zeros, $n(t)=sum_{|lambda_n|le t}1$, $N(r)=int_0^r t^{-1}n(t), dt$, $r>0$, $h(varphi)$ be the indicator of $f$, and $F(z)=zf'(z)/f(z)$, $z=re^{ivarphi}$. An entire function $f$ is called a function of improved regular growth if for some $rhoin (0,+infty)$ and $rho_1in (0,rho)$, and a $2pi$-periodic $rho$-trigonometrically convex function $h(varphi)notequiv -infty$ there exists a set $Usubsetmathbb C$ contained in the union of disks with finite sum of radii and such thatbegin{equation*}log |{f(z)}|=|z|^rho h(varphi)+o(|z|^{rho_1}),quad Unotni z=re^{ivarphi}toinfty.end{equation*}In this paper, we prove that an entire function $f$ of order $rhoin (0,+infty)$ with zeros on a finite system of rays ${z: arg z=psi_{j}}$, $jin{1,ldots,m}$, $0lepsi_1
让 $f$ 是一个完整的函数 $f(0)=1$, $(lambda_n)_{ninmathbb N}$ 是0的序列, $n(t)=sum_{|lambda_n|le t}1$, $N(r)=int_0^r t^{-1}n(t), dt$, $r>0$, $h(varphi)$ 成为…的指示者 $f$,和 $F(z)=zf'(z)/f(z)$, $z=re^{ivarphi}$. 一个完整的函数 $f$ 对某些人来说,它被称为改善常规增长的函数吗 $rhoin (0,+infty)$ 和 $rho_1in (0,rho)$,和 $2pi$-周期性的 $rho$-三角凸函数 $h(varphi)notequiv -infty$ 存在一个集合 $Usubsetmathbb C$ 包含在具有有限半径和的盘的并集中,并且这样begin{equation*}log |{f(z)}|=|z|^rho h(varphi)+o(|z|^{rho_1}),quad Unotni z=re^{ivarphi}toinfty.end{equation*}在本文中,我们证明了一个完整的函数 $f$ 有序的 $rhoin (0,+infty)$ 在有限的射线系统中有零 ${z: arg z=psi_{j}}$, $jin{1,ldots,m}$, $0lepsi_1
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引用次数: 1
INHOMOGENEOUS DIFFERENTIAL EQUATIONS OF VECTOR ORDER WITH DISSIPATIVE PARABOLICITY AND POSITIVE GENUS 具有耗散抛物性和正格的矢量阶非齐次微分方程
Pub Date : 1900-01-01 DOI: 10.31861/bmj2022.02.10
V. Litovchenko, M. Gorbatenko
Parabolicity in the sense of both Petrosky and Shilov has a scalar character. It is not able to take into account the specificity of the heterogeneity of the environment. In this regard, in the early 70-s, S.D. Eidelman proposed the so-called $vec{2b}$-parabolicity, which is a natural generalization of the Petrovsky parabolicity for the case of an anisotropic medium. A detailed study of the Cauchy problem for equations with such parabolicity was carried out in the works of S.D. Eidelman, S.D. Ivasishena, M.I. Matiichuk and their students.An extension of parabolicity according to Shilov for the case of anisotropic media is ${vec{p},vec h}$-parabolicity. The class of equations with such parabolicity is quite broad, it includes the classes of Eidelman, Petrovskii, and Shilov and allows unifying the classical theory of the Cauchy problem for parabolic equations.In this work, for inhomogeneous ${vec{p},vec h}$-parabolic equations with vector positive genus, the conditions under which the Cauchy problem in the class of generalized initial functions of the type of Gelfand and Shilov distributions will be correctly solvable are investigated. At the same time, the inhomogeneities of the equations are continuous functions of finite smoothness with respect to the set of variables, which decrease with respect to the spatial variable, and are unbounded with the integrable feature with respect to the time variable.
彼得罗夫斯基和希洛夫意义上的抛物性都具有标量特征。它不能考虑到环境异质性的特殊性。在这方面,在70年代早期,S.D. Eidelman提出了所谓的$vec{2b}$-抛物线性,这是对各向异性介质情况下Petrovsky抛物线性的自然推广。在S.D. Eidelman、S.D. Ivasishena、M.I. Matiichuk及其学生的著作中,详细地研究了此类抛物性方程的柯西问题。各向异性介质的抛物性根据希洛夫的推广是${vec{p},vec h}$-抛物性。具有抛物性的方程类是相当广泛的,它包括Eidelman, Petrovskii和Shilov类,并允许统一抛物方程的柯西问题的经典理论。本文研究了具有向量正属的非齐次${vec{p},vec h}$-抛物型方程中具有Gelfand分布和Shilov分布的广义初始函数类的Cauchy问题正确可解的条件。同时,方程的非齐次性对于变量集是有限光滑的连续函数,对于空间变量是递减的,对于时间变量是无界的。
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引用次数: 0
On some properties of solutions of linear differential equations according to given sequences 给定序列下线性微分方程解的若干性质
Pub Date : 1900-01-01 DOI: 10.31861/bmj2019.01.121
O. Shavala
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引用次数: 0
MODELING HARVESTING PROCESSES FOR POPULATIONS WITH NON-OVERLAPPING GENERATIONS 代不重叠种群的收获过程建模
Pub Date : 1900-01-01 DOI: 10.31861/bmj2022.02.12
V. Matsenko
Difference equations are used in order to model the dynamics of populations with non-overlapping generations, since the growth of such populations occurs only at discrete points in time.In the simplest case such equations have the form $N_{t+1}= F(N_t)$, where $N_t >0$ is the population size at a moment of time $t$, and $F$ is a smooth function.Among such equations the discrete logistic equation and Ricker's equation are most often used in practice.In the given paper, these equations are considered width taking into account an effect of harvesting, that is, the equations of the form below are studied $N_{t+1}=r N_t (1- N_t) - c$ and $N_{t+1}= N_t exp (r(1 - N_t / K )) - c$, where the parameters $r$, $K>0$, $c>0$ are harvesting intensity.Positive equilibrium points and conditions for their stability for these equations were found. These kinds of states are often realized in nature.For practice, periodic solutions are also important, especially with periods $T=2 (N_{t+2} = N_t)$ and $T=3 (N_{t+3} = N_t)$, since, with their existence, by Sharkovskii's theorem, one can do conclusions about the existence of periodic solutions of other periods.For the discrete logistic equation in analytical form, the values that make up the periodic solution with period $T=2$ were found. We used numerical methods in order to find solutions with period $T=3$. For Ricker's model, the question of the existence of periodic solutions can be investigated by computer analysis only.In the paper, a number of computer experiments were conducted in which periodic solutions were found and their stability was studied. For Ricker's model with harvesting, chaotic solutions were also found.As we can see, the study of difference equations gives many unexpected results.
差分方程是为了模拟非重叠世代群体的动力学,因为这种群体的增长只发生在离散的时间点上。在最简单的情况下,这样的方程具有$N_{t+1}= F(N_t)$的形式,其中$N_t >0$是在时刻$t$的人口规模,$F$是一个光滑函数。在这些方程中,离散logistic方程和Ricker方程在实际应用中最为常用。在本文中,考虑到收获的影响,这些方程被认为是宽度,即研究了如下形式的方程$N_{t+1}=r N_t (1- N_t) - c$和$N_{t+1}= N_t exp (r(1 - N_t / K)) - c$,其中参数$r$, $K>0$, $c>0$为收获强度。找到了这些方程的正平衡点及其稳定性条件。这些状态通常在自然界中实现。在实践中,周期解也很重要,特别是周期$T=2 (N_{T +2} = N_t)$和$T=3 (N_{T +3} = N_t)$,因为有了它们的存在性,根据Sharkovskii定理,就可以得出其他周期周期解的存在性的结论。对于解析型离散logistic方程,找到了构成周期$T=2$的周期解的值。我们用数值方法来求周期为T=3的解。对于Ricker模型,周期解的存在性问题只能用计算机分析来研究。本文进行了一系列计算机实验,找到了周期解,并研究了周期解的稳定性。对于带收获的Ricker模型,也发现了混沌解。我们可以看到,研究差分方程会得到许多意想不到的结果。
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引用次数: 0
ON APPROXIMATION OF ALMOST-PERIODIC SOLUTIONS FOR A NON-LINEAR COUNTABLE SYSTEM OF DIFFERENTIAL EQUATIONS BY QUASI-PERIODIC SOLUTIONS FOR SOME LINEAR SYSTEM 一类非线性可数微分方程系统的概周期解的拟周期解逼近
Pub Date : 1900-01-01 DOI: 10.31861/bmj2021.02.09
Yuri V Teplinsky
It is well-known that many applied problems in different areas of mathematics, physics, and technology require research into questions of existence of oscillating solutions for differential systems, which are their mathematical models. This is especially true for the problems of celestial mechanics. Novadays, by oscillatory motions in dynamical systems, according to V. V. Nemitsky, we call their recurrent motions. As it is known from Birkhoff theorem, trajectories of such motions contain minimal compact sets of dynamical systems. The class of recurrent motions contains, in particular, both quasi-periodic and almost-periodic motions. There are renowned fundamental theorems by Amerio and Favard related to existence of almost-periodic solutions for linear and non-linear systems. It is also of interest to research the behavior of a dynamical system’s motions in a neighborhood of a recurrent trajectory. It became understoodlater, that the question of existence of such trajectories is closely related to existence of invariant tori in such systems, and the method of Green-Samoilenko function is useful for constructing such tori. Here we consider a non-linear system of differential equations defined on Cartesian product of the infinite-dimensional torus T∞ and the space of bounded number sequences m. The problem is to find sufficient conditions for the given system of equations to possess a family of almost-periodic in the sense of Bohr solutions, dependent on the parameter ψ ∈ T∞, every one of which can be approximated by a quasi-periodic solution of some linear system of equations defined on a finite-dimensional torus.
众所周知,在数学、物理和技术的不同领域中,许多应用问题都需要研究微分系统的振荡解的存在性问题,这是它们的数学模型。对于天体力学的问题尤其如此。今天,根据内米茨基的说法,动力系统中的振荡运动,我们称之为循环运动。从Birkhoff定理可知,这类运动的轨迹包含动力系统的最小紧集。循环运动的类别包括,特别地,准周期和近周期运动。Amerio和Favard提出了关于线性和非线性系统的概周期解存在性的著名基本定理。研究动力系统在循环轨迹附近的运动行为也是有意义的。后来人们认识到,这种轨迹的存在性问题与这种系统中不变环面的存在性密切相关,Green-Samoilenko函数的方法对于构造这种环面是有用的。这里我们考虑一个非线性微分方程组的笛卡儿积的定义无限维的环面T∞和有限的空间序列m。问题是找到充分条件给定的方程组拥有一个家庭的概周期的波尔的解决方案,依赖于参数ψ∈T∞,每一层可以用准周期解的近似线性方程组上定义一个有限维环面。
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引用次数: 0
THE CRITERION FOR TRANSFERABLE SELF-CONSISTENTLY TRANSLATIONALITY OF COORDINATE TRANSFORM OPERATORS AND REFERENCE FRAMES IN UNIVERSAL KINEMATICS 通用运动学中坐标变换算子和参照系可转移自洽平动性的判据
Pub Date : 1900-01-01 DOI: 10.31861/bmj2021.01.10
Y. Grushka
From an intuitive point of view universal kinematics are collections (sets) of changingobjects, which evolve, being in a certain spatial-geometric environment, and evolution of whi-ch can be observed from many different frames of reference. Moreover, the definition of uni-versal kinematics impose the existence of some (preassigned) universal coordinate transformbetween every two reference frames of such kinematics. Transferable self-consistently translati-onal reference frames (in vector universal kinematics) are interesting because for such referenceframes it is possible to give a clear and unambiguous definition of displacement of a movingreference frame relative to a fixed one, which does not depend on the choice of a fixed point in themoving frame of reference. In the present paper it is shown that an arbitrary reference frame mis transferable self-consistently translational relatively to a reference frame l (in some vector uni-versal kinematics F) if and only if the coordinate transform operator from the reference framem to the reference frame l is transferable self-consistently translational. Therefore transferableself-consistently translational coordinate transform operators describe the conversion of coordi-nates from the moving and transferable self-consistently translational frame of reference to the(given) fixed frame in vector universal kinematics. Also in the paper it is described the structureof transferable self-consistently translational coordinate transform operators (this is the mainresult of the article). Using this result it have been obtained the necessary and sufficient conditi-on for transferable self-consistently translationality of one reference frame relatively to anotherin vector universal kinematics.
从直观的角度来看,通用运动学是变化物体的集合(集合),它们在一定的空间几何环境中演化,并且可以从许多不同的参照系中观察其演化。此外,通用运动学的定义要求在这种运动学的每两个参考系之间存在某种(预先指定的)通用坐标变换。可转移的自一致平移参考系(在矢量通用运动学中)是有趣的,因为对于这样的参考系,可以给出运动参考系相对于固定参考系的位移的清晰和明确的定义,这并不依赖于运动参考系中固定点的选择。本文证明了当且仅当从参考系到参考系l的坐标变换算子为可自洽平移时,任意参考系相对于参考系l是可自洽平移的(在某向量通用运动学F中)。因此,在矢量通用运动学中,可转移自洽平移坐标变换算子描述了从运动的可转移自洽平移参照系到给定固定参照系的坐标转换。本文还描述了可转移自洽平移坐标变换算子的结构(这是本文的主要成果)。利用这一结果,得到了在矢量通用运动学中一个参照系相对于另一个参照系可自洽平移的充分必要条件。
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引用次数: 0
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Bukovinian Mathematical Journal
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