673 research outputs found
The damped wave equation with acoustic boundary conditions and non-locally reacting surfaces
No full textThe aim of the paper is to study the problem
⎧⎩⎨⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪utt+dut−c2Δu=0μvtt−divΓ(σ∇Γv)+δvt+κv+ρut=0vt=∂νu∂νu=0u(0,x)=u0(x),ut(0,x)=u1(x)v(0,x)=v0(x),vt(0,x)=v1(x)inR×Ω,onR×Γ1,onR×Γ1,onR×Γ0,inΩ,onΓ1,
where Ω
is a open domain of RN with uniformly Cr boundary (N≥2, r≥1), Γ=∂Ω, (Γ0,Γ1) is a relatively open partition of Γ with Γ0 (but not Γ1) possibly empty. Here divΓ and ∇Γ denote the Riemannian divergence and gradient operators on Γ, ν is the outward normal to Ω, the coefficients μ,σ,δ,κ,ρ are suitably regular functions on Γ1 with ρ,σ and μ uniformly positive, d is a suitably regular function in Ω and c is a positive constant. In this paper we first study well-posedness in the natural energy space and give regularity results. Hence we study asymptotic stability for solutions when Ω is bounded, Γ1 is connected, r=2, ρ is constant and κ,δ,d≥0
On Structured Perturbations of Positive Semigroups
No full textIn this thesis we study perturbation results for the generator A of a positive C_0--semigroup on a Banach lattice X. We generalize results that hold for an AM- or AL-space X and extend them to an arbitrary Banach lattice X in case the perturbation can be factorized as P=BC via an AM- or AL-space U. This allows to deal with applications on (infinite dimensional) reflexive Banach spaces, which are a priori excluded if X is an AM- or an AL-space.
First, B and C are assumed to be positive operators satisfying the spectral condition r(CR(\lambda,A_{-1})B)\omega_0(A). We then prove that the generation results obtained in this case still hold when B and C are not necessarily positive, but only dominated by positive operators. These abstract results are applied to domain perturbations of generators, a heat equation with boundary feedback and perturbations of the first derivative.
Combining the previous results we then deal with "doubly unbounded" perturbations P:Z\to X_{-1}, provided they can be factorized as P=BC via U=\mathbb{R}^N. In this context, we prove a Staffans--Weiss type perturbation result. We show that the classically assumed admissibility and invertibility conditions for the associated input--output map \mathcal{F}_\infty follow from the (much simpler to verify) spectral condition mentioned above. The abstract results are applied to domain perturbations and finite rank perturbations of the first derivative
On structured finite–rank perturbations of positive operator semigroups
No full textIn this note, we give a Weiss–Staffans type perturbation result for
the generator A of a positive semigroup on a Banach lattice X. Assuming
that the perturbation P : Z → X−1 can be factorized as P = BC for positive
operators C : Z → RN and B : R^N → X−1 , we show that the admissibility and
invertibility conditions for the associated input-output map F_∞ follow from
the spectral condition r(CR(λ, A_−1 )B) < 1 for some λ > ω_0 (A). The abstract
results are applied to domain perturbations of generators and perturbations of
the first derivative
Perturbations of positive semigroups Factorized via AM– and AL-spaces
No full textIn this note we extend perturbation results for positive C_0 -semigroups on AM- and AL-spaces
generalizing them to arbitrary Banach lattices in case the perturbation can be factorized appropriately. The
abstract results are applied to domain perturbations of generators, a heat equation with boundary feedback
and perturbations of the first derivative
Reversibility and quantum coherence in one-dimensional quantum cellular automata
No full textQuantum cellular automata are important tools in understanding quantum dynamics, thanks to their simple and effective list of rules. Here we consider a class of noisy, one-dimensional quantum cellular automata that allow one to shift from unitary dynamics to completely positive maps, investigating the evolution of coherence as well as the notion of reversibility in such a setting. To this aim, we associate an approximate reverse automaton to each noisy automaton, and assess its effect, and we define an irreversibility time based on the distance from the maximally mixed state, which is shown to be the only attractor of the automaton map in the presence of dephasing. Our analysis illustrates the interplay between unitary and noisy dynamics
Indagine sul popolamento ittico della Val Staffora (Pavia). 1° contributo: marcatura di trote per valutazioni ambientali
No full textFirms, Technological innovation, Digital competencies, and Labour markets dynamics
No full textIn this contribution, we aim to conduct a factorial survey experiment to analyse the degree to which recruiters in different productive and institutional systems rely on information about job candidates’ digital skills to evaluate their suitability for different job vacancies. Specifically, we aim to answer the following questions: Do digital skills, relative to other individual attributes of jobseekers, play any specific role in the process of recruitment? What is the importance of different skill levels for raising job candidates’ appeal? The experiment will be replicated in three European countries with very different labour markets and systems of education and training: Germany, Italy, and the United Kingdom
The reason why to comment an important collective agreement at the company level
No full textThe Author presents the comment to the corporate collective agreement Takeaway.com Express Italy (JustEatTakeaway group), in the section Reports & Comments of the journal. Some leading figures of the negotiation and a group of academics were asked to comment on the genesis and the most relevant legal aspects of the collective agreement, given its novelty. The agreement, in fact, has the purpose to combine the flexible organization of the company with a network of rider, hired, for the first time in Italy, as employees
Quantum Gate-State Propagation via Entangled Qubit Mirroring: A Framework for Coherent Logic Inference Without Measurement
No full textThis white paper introduces a theoretical framework for quantum information propagation using entangled qubit pairs to mirror logic gate sequences without measurement or classical signaling.
By maintaining qubits in superposition and coherence, the paper explores how quantum logic operations performed on one qubit may be inferred through its entangled partner — potentially laying the groundwork for nonlocal quantum processing, mirrored quantum buses, and next-generation quantum networks.
Author: John Barbieri, Independent Researcher in Quantum Communication Theory
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