共查询到20条相似文献,搜索用时 15 毫秒
1.
F. E. Lomovtsev 《Differential Equations》2008,44(6):866-871
We prove the well-posed solvability in the strong sense of the boundary value Problems where the unbounded operators A s (t), s > 0, in a Hilbert space H have domains D(A s (t)) depending on t, are subordinate to the powers A 1?(s?1)/2m (t) of some self-adjoint operators A(t) ≥ 0 in H, are [(s+1)/2] times differentiable with respect to t, and satisfy some inequalities. In the space H, the maximally accretive operators A 0(t) and the symmetric operators A s (t), s > 0, are approximated by smooth maximally dissipative operators B(t) in such a way that , where the smoothing operators are defined by .
相似文献
$$\begin{gathered} ( - 1)\frac{{_m d^{2m + 1} u}}{{dt^{2m + 1} }} + \sum\limits_{k = 0}^{m - 1} {\frac{{d^{k + 1} }}{{dt^{k + 1} }}} A_{2k + 1} (t)\frac{{d^k u}}{{dt^k }} + \sum\limits_{k = 1}^m {\frac{{d^k }}{{dt^k }}} A_{2k} (t)\frac{{d^k u}}{{dt^k }} + \lambda _m A_0 (t)u = f, \hfill \\ t \in ]0,t[,\lambda _m \geqslant 1, \hfill \\ {{d^i u} \mathord{\left/ {\vphantom {{d^i u} {dt^i }}} \right. \kern-\nulldelimiterspace} {dt^i }}|_{t = 0} = {{d^j u} \mathord{\left/ {\vphantom {{d^j u} {dt^j }}} \right. \kern-\nulldelimiterspace} {dt^j }}|_{t = T} = 0,i = 0,...,m,j = 0,...,m - 1,m = 0,1,..., \hfill \\ \end{gathered} $$
$$\begin{gathered} \mathop {lim}\limits_{\varepsilon \to 0} Re(A_0 (t)B_\varepsilon ^{ - 1} (t)(B_\varepsilon ^{ - 1} (t))^ * u,u)_H = Re(A_0 (t)u,u)_H \geqslant c(A(t)u,u)_H \hfill \\ \forall u \in D(A_0 (t)),c > 0, \hfill \\ \end{gathered} $$
$$B_\varepsilon ^{ - 1} (t) = (I - \varepsilon B(t))^{ - 1} ,(B_\varepsilon ^{ - 1} (t)) * = (I - \varepsilon B^ * (t))^{ - 1} ,\varepsilon > 0.$$
2.
L. E. Shaikhet 《Journal of Mathematical Sciences》1993,67(4):3234-3236
We consider the problem of adaptive control by a linear stochastic system with lag
相似文献
3.
Zhuohua Peng 《Numerical Algorithms》2013,64(3):455-480
In this paper, an efficient algorithm is presented for minimizing $\|A_1X_1B_1 + A_2X_2B_2+\cdots +A_lX_lB_l-C\|$ where $\|\cdot \|$ is the Frobenius norm, $X_i\in R^{n_i \times n_i}(i=1,2,\cdots ,l)$ is a reflexive matrix with a specified central principal submatrix $[x_{ij}]_{r\leq i,j\leq n_i-r}$ . The algorithm produces suitable $[X_1,X_2,\cdots ,X_l]$ such that $\|A_1X_1B_1+A_2X_2B_2+\cdots +A_lX_lB_l-C\|=\min $ within finite iteration steps in the absence of roundoff errors. We show that the algorithm is stable any case. The algorithm requires little storage capacity. Given numerical examples show that the algorithm is efficient. 相似文献
4.
In this work, we prove the Cauchy–Kowalewski theorem for the initial-value problem 相似文献
$$\begin{aligned} \frac{\partial w}{\partial t}= & {} Lw \\ w(0,z)= & {} w_{0}(z) \end{aligned}$$ $$\begin{aligned} Lw:= & {} E_{0}(t,z)\frac{\partial }{\partial \overline{\phi }}\left( \frac{ d_{E}w}{dz}\right) +F_{0}(t,z)\overline{\left( \frac{\partial }{\partial \overline{\phi }}\left( \frac{d_{E}w}{dz}\right) \right) }+C_{0}(t,z)\frac{ d_{E}w}{dz} \\&+G_{0}(t,z)\overline{\left( \frac{d_{E}w}{dz}\right) } +A_{0}(t,z)w+B_{0}(t,z)\overline{w}+D_{0}(t,z) \end{aligned}$$ 5.
Dumitru Popa 《Positivity》2014,18(1):29-39
We give the necessary and sufficient conditions for a multilinear bounded operator on $C(\Omega _{1}) \times \cdots \times C(\Omega _{k}) \times X_{k+1}\times \cdots \times X_{k+n}$ to be multiple 1-summing. Based on this result we prove an inclusion result for multiple summing operators and an unexpected composition result of Grothendieck type for bilinear operators. 相似文献
6.
Boban Karapetrović 《Czechoslovak Mathematical Journal》2018,68(2):559-576
We show that if α > 1, then the logarithmically weighted Bergman space \(A_{{{\log }^\alpha }}^2\) is mapped by the Libera operator L into the space \(A_{{{\log }^{\alpha - 1}}}^2\), while if α > 2 and 0 < ε ≤ α?2, then the Hilbert matrix operator H maps \(A_{{{\log }^\alpha }}^2\) into \(A_{{{\log }^{\alpha - 2 - \varepsilon }}}^2\).We show that the Libera operator L maps the logarithmically weighted Bloch space \({B_{{{\log }^\alpha }}}\), α ∈ R, into itself, while H maps \({B_{{{\log }^\alpha }}}\) into \({B_{{{\log }^{\alpha + 1}}}}\).In Pavlovi?’s paper (2016) it is shown that L maps the logarithmically weighted Hardy-Bloch space \(B_{{{\log }^\alpha }}^1\), α > 0, into \(B_{{{\log }^{\alpha - 1}}}^1\). We show that this result is sharp. We also show that H maps \(B_{{{\log }^\alpha }}^1\), α > 0, into \(B_{{{\log }^{\alpha - 1}}}^1\) and that this result is sharp also. 相似文献
7.
For symmetric operators B i (B i = d ?B i ) and positive operators $A_{i}\succeq\tilde{A}_{i}$ , we compare moments of $\|B_{1}A_{1}^{p}+\cdots+B_{n}A_{n}^{p}\|$ and $\|B_{1}\tilde{A}_{1}^{p}+\cdots +B_{n}\tilde{A}_{n}^{p}\|$ . 相似文献
8.
Yu. Ya. Belov 《Mathematical Notes》1976,20(5):948-953
In a Hilbert space H we consider the approximation by systems $$\frac{{d^2 u_1 }}{{dt^2 }} = A_{11} u_1 + A_{12} u_2 + f_1 ,\varepsilon \frac{{d^2 u_2 }}{{dt^2 }} = A_{21} u_1 + A_{22} u_2 + f_2 ,\varepsilon > 0,$$ of the semievolutionary system obtained from (1) when ∈=0. Under certain conditions on the solutions of the Cauchy problem for system (1) and the existence of a bounded linear operator A 22 ?1 we establish the convergence of the solutions u∈(∈ → 0) to a solution of the corresponding problem for system (1) with ∈=0. We also establish the uniform correctness of the Cauchy problem for the above system. 相似文献
9.
M. Barraa 《Proceedings of the American Mathematical Society》2005,133(6):1723-1726
Let and denote two -tuples of operators with and Let denote the elementary operators defined on the Hilbert-Schmidt class by We show that
Here is the essential numerical range, is the joint numerical range and is the joint essential numerical range. 10.
Mohamed A. Ramadan Mokhtar A. Abdel Naby Ahmed M. E. Bayoumi 《Journal of Applied Mathematics and Computing》2014,44(1-2):99-118
This paper is concerned with iterative solution to general Sylvester-conjugate matrix equation of the form $\sum_{i = 1}^{s} A_{i}V + \sum_{j = 1}^{t} B_{j}W = \sum_{l = 1}^{m} E_{l}\overline{V}F_{l} + C$ . An iterative algorithm is established to solve this matrix equation. When this matrix equation is consistent, for any initial matrices, the solutions can be obtained within finite iterative steps in the absence of round off errors. Some lemmas and theorems are stated and proved where the iterative solutions are obtained. Finally, a numerical example is given to verify the effectiveness of the proposed algorithm. 相似文献
11.
We derive the solvability conditions and an expression of the general solution to the system of matrix equations A 1X=C1 , A2Y=C2 , YB2=D2 , Y=Y*, A3Z=C3 , ZB3=D3 , Z=Z*, B4X+(B4X)+C4YC4*+D4ZD4*=A4 . Moreover, we investigate the maximal and minimal ranks and inertias of Y and Z in the above system of matrix equations. As a special case of the results, we solve the problem proposed in Farid, Moslehian, Wang and Wu’s recent paper (Farid F O, Moslehian M S, Wang Q W, et al. On the Hermitian solutions to a system of adjointable operator equations. Linear Algebra Appl, 2012, 437: 1854-1891). 相似文献
12.
Albin L. Jones 《Proceedings of the American Mathematical Society》2008,136(4):1445-1449
We prove that if and , then
13.
Peter Šemrl 《Integral Equations and Operator Theory》2008,62(3):441-454
Let H be a Hilbert space and B
s
(H) the set of all self-adjoint bounded linear operators on H. We describe the general form of bijective maps which preserve comparability in both directions.
This work was partially supported by a grant from the Ministry of Science of Slovenia. 相似文献
14.
Ralph Chill Eva Fašangová 《Calculus of Variations and Partial Differential Equations》2005,22(3):321-342
We study the convergence and decay rate to a steady state of bounded solutions of the nonlinear evolutionary integral equation
and we apply our abstract results to the viscoelastic Euler-Bernoulli beam and to Kelvin-Voigt solids.Received: 25 March 2003, Accepted: 5 April 2004, Published online: 16 July 2004This work was partially supported by the DFG project Regularität und Asymptotik für elliptische und parabolische Probleme and by the grants GAR 201/01/D094, MSM 113200007. 相似文献
15.
Weiping Wang 《The Ramanujan Journal》2013,32(2):159-184
In this paper, by the methods of partial fraction decomposition and generating functions, we establish an explicit expression for sums of products of l Bernoulli polynomials and n?l Euler polynomials, i.e., for sums $$S_n^{(k)}(y;l,k-l):= \sum_{\substack{j_1+\cdots+j_k=n\\j_1,\dots,j_k\geq0}} \binom {n}{j_1,\dots,j_k} B_{j_1}(x_1)\cdots B_{j_l}(x_l)E_{j_{l+1}}(x_{l+1}) \cdots E_{j_k}(x_k). $$ This result is then used to deal with various other types of sums of products of Bernoulli polynomials and Euler polynomials. Some of them are expressed in terms of $S_{n}^{(k)}(y;l,k-l)$ and can be computed directly, while the others satisfy certain recurrences and can be determined recursively. As a consequence, many known results are special cases of ours. 相似文献
16.
W.-H. Lin 《Acta Mathematica Hungarica》2018,156(1):112-131
Let \({\mathcal{H}}\) be a complex Hilbert space, \({\mathcal{B(H)}}\) be the algebra of all bounded linear operators on \({\mathcal{H}}\) and \({\mathcal{A} \subseteq \mathcal{B(H)}}\) be a von Neumann algebra without nonzero central abelian projections. Let \({p_n(x_1,x_2 ,\ldots ,x_n)}\) be the commutator polynomial defined by n indeterminates \({x_1, \ldots , x_n}\) and their skew Lie products. It is shown that a mapping \({\delta \colon \mathcal{A} \longrightarrow \mathcal{B(H)}}\) satisfies 相似文献
$$\delta(p_n(A_1, A_2 ,\ldots , A_n))=\sum_{k=1}^np_n(A_1 ,\ldots , A_{k-1}, \delta(A_k), A_{k+1} ,\ldots , A_n)$$ 17.
Under mild assumption, integral representations of the form
18.
For any prime \(p>3,\) we prove that 相似文献
$$\begin{aligned} \sum _{k=0}^{p-1}\frac{3k+1}{(-8)^k}{2k\atopwithdelims ()k}^3\equiv p\left( \frac{-1}{p}\right) +p^3E_{p-3}\pmod {p^4}, \end{aligned}$$ $$\begin{aligned} \sum _{k=0}^{\frac{p-1}{2}}\frac{6k+1}{(-512)^k}{2k\atopwithdelims ()k}^3\equiv p\left( \frac{-2}{p}\right) \pmod {p^2} \end{aligned}$$ 19.
A famous dominated compactness theorem due to Krasnosel’skiĭ states that compactness of a regular linear integral operator in L
p
follows from that of a majorant operator. This theorem is extended to the case of the spaces , with variable exponent p(·), where we also admit power type weights . This extension is obtained as a corollary to a more general similar dominated compactness theorem for arbitrary Banach function
spaces for which the dual and associate spaces coincide. The result on compactness in the spaces is applied to fractional integral operators over bounded open sets.
Submitted: June 6, 2007. Accepted: November 20, 2007. 相似文献
20.
V. E. Slyusarchuk 《Mathematical Notes》1975,17(6):552-554
For a linear differential equation of the type
|