185,670 research outputs found
Characterization of unwanted noise in realistic cavities
The problem of the description of absorption and scattering losses in high-Q
cavities is studied. The considerations are based on quantum noise theories,
hence the unwanted noise associated with scattering and absorption is taken
into account by introduction of additional damping and noise terms in the
quantum Langevin equations and input--output relations. Completeness conditions
for the description of the cavity models obtained in this way are studied and
corresponding replacement schemes are discussed.Comment: Contribution to XI International Conference on Quantum Optics, Minsk,
Belarus, 26-31 May, 200
Event-triggered Pulse Control with Model Learning (if Necessary)
In networked control systems, communication is a shared and therefore scarce
resource. Event-triggered control (ETC) can achieve high performance control
with a significantly reduced amount of samples compared to classical, periodic
control schemes. However, ETC methods usually rely on the availability of an
accurate dynamics model, which is oftentimes not readily available. In this
paper, we propose a novel event-triggered pulse control strategy that learns
dynamics models if necessary. In addition to adapting to changing dynamics, the
method also represents a suitable replacement for the integral part typically
used in periodic control.Comment: Accepted final version to appear in: Proc. of the American Control
Conference, 201
On convergence rates equivalency and sampling strategies in functional deconvolution models
Using the asymptotical minimax framework, we examine convergence rates
equivalency between a continuous functional deconvolution model and its
real-life discrete counterpart over a wide range of Besov balls and for the
-risk. For this purpose, all possible models are divided into three
groups. For the models in the first group, which we call uniform, the
convergence rates in the discrete and the continuous models coincide no matter
what the sampling scheme is chosen, and hence the replacement of the discrete
model by its continuous counterpart is legitimate. For the models in the second
group, to which we refer as regular, one can point out the best sampling
strategy in the discrete model, but not every sampling scheme leads to the same
convergence rates; there are at least two sampling schemes which deliver
different convergence rates in the discrete model (i.e., at least one of the
discrete models leads to convergence rates that are different from the
convergence rates in the continuous model). The third group consists of models
for which, in general, it is impossible to devise the best sampling strategy;
we call these models irregular. We formulate the conditions when each of these
situations takes place. In the regular case, we not only point out the number
and the selection of sampling points which deliver the fastest convergence
rates in the discrete model but also investigate when, in the case of an
arbitrary sampling scheme, the convergence rates in the continuous model
coincide or do not coincide with the convergence rates in the discrete model.
We also study what happens if one chooses a uniform, or a more general
pseudo-uniform, sampling scheme which can be viewed as an intuitive replacement
of the continuous model.Comment: Published in at http://dx.doi.org/10.1214/09-AOS767 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
On the stability of the recently developed nice integration scheme
The paper deals with the integration of elasto-plastic constitutive models using recently developed NICE integration scheme [1],[2]. The emphasis is put on the stability of the integration, since this issue was not sufficiently addressed in previous publications of the NICE. Nonlinear boundary value problems are nowadays typically solved numerically using finite element method (FEM) with implicit “static” (e.g. ABAQUS/Standard) or explicit “dynamic” approach (e.g. ABAQUS/Explicit). The NICE scheme was primarily developed for the integration of elasto-plastic constitutive models within explicit integration of a given boundary value problem, as a replacement for traditionally used backward-Euler scheme. The simplicity of the implementation, more than satisfactory accuracy and low time consumption of calculation, certainly outperforms the properties of other available schemes, including properties of the backward-Euler scheme. The only open issue regarding the NICE scheme is its conditional stability, which originates from the integration of evolution equations in a “forward” manner, whereas the backward-Euler scheme exhibits unconditional stability. The aim of this paper is to derive stable time increment for the NICE scheme and to show, that for practical quasi-static applications it is much larger than the stable time increment size given for the integration of dynamic boundary value problem equations
Existentially Closed Models and Conservation Results in Bounded Arithmetic
We develop model-theoretic techniques to obtain conservation results for first order Bounded Arithmetic theories, based on a hierarchical version of the well-known notion of an existentially closed model. We focus on the classical Buss' theories Si2 and Ti2 and prove that they are ∀Σbi conservative over their inference rule counterparts, and ∃∀Σbi conservative over their parameter-free versions. A similar analysis of the Σbi-replacement scheme is also developed. The proof method is essentially the same for all the schemes we deal with and shows that these conservation results between schemes and inference rules do not depend on the specific combinatorial or arithmetical content of those schemes. We show that similar conservation results can be derived, in a very general setting, for every scheme enjoying some syntactical (or logical) properties common to both the induction and replacement schemes. Hence, previous conservation results for induction and replacement can be also obtained as corollaries of these more general results.Ministerio de Educación y Ciencia MTM2005-08658Junta de Andalucía TIC-13
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