| 1. |
- Aiki, Toyohiko, et al.
(författare)
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Large-time behavior of solutions to a thermo-diffusion system with Smoluchowski interactions
- 2017
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Ingår i: Journal of Differential Equations. - : Elsevier. - 0022-0396 .- 1090-2732. ; 5:5, s. 3009-3026
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Tidskriftsartikel (refereegranskat)abstract
- We prove the large time behavior of solutions to a coupled thermo-diffusion arising in the modeling of the motion of hot colloidal particles in porous media. Additionally, we also ensure the uniqueness of solutions of the target problem. The main mathematical difficulty is due to the presence in the right-hand side of the equations of products between temperature and concentration gradients. Such terms mimic the so-called thermodynamic Soret and Dufour effects. These are cross-coupling terms emphasizing in this context a strong interplay between heat conduction and molecular diffusion.
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| 2. |
- Aleksanyan, Hayk, et al.
(författare)
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Applications of Fourier analysis in homogenization of Dirichlet problem I. Pointwise estimates
- 2013
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Ingår i: Journal of Differential Equations. - : Elsevier BV. - 0022-0396 .- 1090-2732. ; 254:6, s. 2626-2637
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we prove convergence results for homogenization problem for solutions of partial differential system with rapidly oscillating Dirichlet data. Our method is based on analysis of oscillatory integrals. In the uniformly convex and smooth domain, and smooth operator and boundary data, we prove pointwise convergence results, namely vertical bar u(epsilon)(x) - u(0)(x)vertical bar <= C-kappa epsilon((d-1)/2) 1/d(x)(kappa), for all x is an element of D, for all kappa > d - 1, where u(epsilon) and u(0) are solutions of respectively oscillating and homogenized Dirichlet problems, and d(x) is the distance of x from the boundary of D. As a corollary for all 1 <= p < infinity we obtain L-P convergence rate as well.
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| 3. |
- Alexandersson, Per, 1987-, et al.
(författare)
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Linear first order differential operators and their Hutchinson invariant sets
- 2024
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Ingår i: Journal of Differential Equations. - 0022-0396 .- 1090-2732. ; 391, s. 265-320
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we initiate the study of a new interrelation between linear ordinary differential operators and complex dynamics which we discuss in detail in the simplest case of operators of order 1. Namely, assuming that such an operator T has polynomial coefficients, we interpret it as a continuous family of Hutchinson operators acting on the space of positive powers of linear forms. Using this interpretation of T, we introduce its continuously Hutchinson invariant subsets of the complex plane and investigate a variety of their properties. In particular, we prove that for any T with non-constant coefficients, there exists a unique minimal under inclusion invariant set MTCH and find explicitly what operators T have the property that MTCH=C.
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| 4. |
- Anderson, Anders, et al.
(författare)
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Measuring the Added Value of Stock Recommendations
- 2020
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Ingår i: Journal of Financial and Quantitative Analysis. - : Cambridge University Press (CUP): HSS Journals. - 0022-1090. ; 55:6, s. 1915-1945
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Tidskriftsartikel (refereegranskat)abstract
- Using data from the Stockholm Stock Exchange (SSE), we study the value added by (as distinct from the abnormal returns to) analysts' recommendations. Recommending brokers' clients trade profitably around positive recommendations at the expense of other brokers' clients. Significant profits come from transactions before recommendation dates. Value added is greatest for upgrades to large caps, and largely insignificant for downgrades and recommendations of small caps, despite high abnormal returns. Brokers making profitable recommendations generate abnormally high commission income, recouping much of their clients' abnormal profits, and their abnormal commission income varies in line with the abnormal profits for their clients.
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| 5. |
- Andersson, Björn, et al.
(författare)
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Exact admission-control for integrated aperiodic and periodic tasks
- 2007
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Ingår i: Journal of Computer and System Sciences. - : Elsevier BV. - 1090-2724 .- 0022-0000. ; 73:2, s. 225-241
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Tidskriftsartikel (refereegranskat)abstract
- Admission-controllers are used to prevent overload in systems with dynamically arriving tasks. Typically, these admission-controllers are based on sufficient (but not necessary) capacity bounds in order to maintain a low computational complexity. In this paper we present how exact admission-control for aperiodic tasks can be efficiently obtained. Our first result is an admission-controller for purely aperiodic task sets where the test has the same runtime complexity as utilization-based tests. Our second result is an extension of the previous controller for a baseload of periodic tasks. The runtime complexity of this test is lower than for any known exact admission-controller. In addition to presenting our main algorithm and evaluating its performance, we also discuss some general issues concerning admission-controllers and their implementation. (C) 2006 Elsevier Inc. All rights reserved.
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| 6. |
- Andersson, John
(författare)
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On the regularity of a free boundary near contact points with a fixed boundary
- 2007
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Ingår i: Journal of Differential Equations. - : Elsevier BV. - 0022-0396 .- 1090-2732. ; 232:1, s. 285-302
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the regularity of a free boundary near contact points with a fixed boundary, with C boundary data, for an obstacle-like free boundary problem. We will show that under certain assumptions on the solution, and the boundary function, the free boundary is uniformly C 1 up to the fixed boundary. We will also construct some examples of irregular free boundaries.
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| 7. |
- Andersson, John, et al.
(författare)
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Optimal regularity for the obstacle problem for the p-Laplacian
- 2015
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Ingår i: Journal of Differential Equations. - : Elsevier. - 0022-0396 .- 1090-2732. ; 259:6, s. 2167-2179
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we discuss the obstacle problem for the p-Laplace operator. We prove optimal growth results for the solution. Of particular interest is the point-wise regularity of the solution at free boundary points. The most surprising result we prove is the one for the p-obstacle problem: Find the smallest u such thatdiv(|∇u|p-2∇u)≤0,u≥ϕ,in B1, with ϕ∈C1,1(B1) and given boundary datum on ∂B1. We prove that the solution is uniformly C1,1 at free boundary points. Similar results are obtained in the case of an inhomogeneity belonging to L∞. When applied to the corresponding parabolic problem, these results imply that any solution which is Lipschitz in time is C1,1p-1 in the spatial variables.
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| 8. |
- Andreasson, Håkan, 1966
(författare)
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Sharp bounds on 2m/r of general spherically symmetric static objects
- 2008
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Ingår i: Journal of Differential Equations. - : Elsevier BV. - 1090-2732 .- 0022-0396. ; 245:8, s. 2243-2266
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Tidskriftsartikel (refereegranskat)abstract
- In 1959 Buchdahl [H.A. Buchdahl, General relativistic fluid spheres, Phys. Rev. 116 (1959) 1027-1034] obtained the inequality 2 M / R ≤ 8 / 9 under the assumptions that the energy density is non-increasing outwards and that the pressure is isotropic. Here M is the ADM mass and R the area radius of the boundary of the static body. The assumptions used to derive the Buchdahl inequality are very restrictive and for instance neither of them hold in a simple soap bubble. In this work we remove both of these assumptions and consider any static solution of the spherically symmetric Einstein equations for which the energy density ρ ≥ 0, and the radial and tangential pressures p ≥ 0 and pT satisfy p + 2 pT ≤ Ω ρ, Ω > 0, and we show thatunder(sup, r > 0) frac(2 m (r), r) ≤ frac((1 + 2 Ω)2 - 1, (1 + 2 Ω)2), where m is the quasi-local mass, so that in particular M = m (R). We also show that the inequality is sharp under these assumptions. Note that when Ω = 1 the original bound by Buchdahl is recovered. The assumptions on the matter model are very general and in particular any model with p ≥ 0 which satisfies the dominant energy condition satisfies the hypotheses with Ω = 3.
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| 9. |
- Aumann, Y., et al.
(författare)
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Linear-consistency testing
- 2001
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Ingår i: Journal of computer and system sciences (Print). - : Elsevier BV. - 0022-0000 .- 1090-2724. ; 62:4, s. 589-607
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Tidskriftsartikel (refereegranskat)abstract
- We extend the notion of linearity testing to the task of checking linear consistency of multiple functions. Informally, functions are linear if their graphs form straight lines on the plane. Two such functions are consistent if the lines have the same slope. We propose a variant of a test of M. Blum et al. (J. Comput. System Sci. 47 (1993), 549-595) to check the linear consistency of three functions f(1). f(2). f(3) mapping a finite Abelian group G to an Abelian group H: Pick x, y is an element of G uniformly and independently at random and check if f(1)(x) + f(2)(y) = f(3)(x + y). We analyze this test for two cases: (1) G and H are arbitrary Abelian groups and (2) G = F-2(n) and H = F-2. Questions bearing close relationship to linear-consistency testing seem to hav e been implicitly considered in recent work on the construction of PCPs and in particular in the work of J. Hastad [9] (in Proceedings of the Twenty-Ninth Annual ACM Symposium on Theory of Computing. El Paso. Texas, 4-6 May 1997, pp. 1-10). It is abstracted explicitly for the first time here. As an application of our results we give yet another new and tight characterization of NP. namely For All epsilon > 0, NP = MIP1-epsilon 1/2 [O(log n), 3, 1]. That is, every language in NP has 3-prover 1-round proof systems in which the verifier tosses O(log n) coins and asks each of the three provers one question each. The provers respond with one bit each such that the verifier accepts instance of the language with probability 1 - epsilon and rejects noninstances with probability at least;. Such a result is of some interest in the study of probabilistically checkable proofs.
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| 10. |
- Autili, Marco, et al.
(författare)
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Automated synthesis of application-layer connectors from automata-based specifications
- 2019
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Ingår i: Journal of computer and system sciences (Print). - : Elsevier. - 0022-0000 .- 1090-2724. ; 104, s. 17-40
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Tidskriftsartikel (refereegranskat)abstract
- Ubiquitous and Pervasive Computing, and the Internet of Things, promote dynamic interaction among heterogeneous systems. To achieve this vision, interoperability among heterogeneous systems represents a key enabler, and mediators are often built to solve protocol mismatches. Many approaches propose the synthesis of mediators. Unfortunately, a rigorous characterization of the concept of interoperability is still lacking, hence making hard to assess their applicability and soundness. In this paper, we provide a framework for the synthesis of mediators that allows us to: (i) characterize the conditions for the mediator existence and correctness; and (ii) establish the applicability boundaries of the synthesis method.
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