37,296 research outputs found
Stochastic Maximum Principle for a PDEs with noise and control on the boundary
In this paper we prove necessary conditions for optimality of a stochastic
control problem for a class of stochastic partial differential equations that
is controlled through the boundary. This kind of problems can be interpreted as
a stochastic control problem for an evolution system in an Hilbert space. The
regularity of the solution of the adjoint equation, that is a backward
stochastic equation in infinite dimension, plays a crucial role in the
formulation of the maximum principle.Comment: 15pg
SGR 1806-20 and the gravitational wave detectors EXPLORER and NAUTILUS
The activity of the soft gamma ray repeater SGR 1806-20 is studied in
correlation with the EXPLORER and NAUTILUS data, during the year 2004, for
gravitational wave (GW) short signal search. Corresponding to the most
significant triggers, the bright outburst on October 5th and the giant flare
(GF) on December 27th, the associated GW signature is searched. Two methods are
employed for processing the data. With the average-modulus algorithm, the
presence of short pulses with energy Egw \geq 1.8 x 10^49 erg is excluded with
90% probability, under the hypothesis of isotropic emission. This value is
comparable to the upper limits obtained by LIGO regarding similar sources.
Using the cross-correlation method, we find a discrepancy from the
null-hypothesis of the order of 1%. This statistical excess is not sufficient
to claim a systematic association between the gravitational and the
electromagnetic radiations, because the estimated GW upper limits are yet
several orders of magnitude far away from the theoretically predicted levels,
at least three for the most powerful SGR flare.Comment: Accepted by Physical Review
Infinite Horizon and Ergodic Optimal Quadratic Control for an Affine Equation with Stochastic Coefficients
We study quadratic optimal stochastic control problems with control dependent
noise state equation perturbed by an affine term and with stochastic
coefficients. Both infinite horizon case and ergodic case are treated. To this
purpose we introduce a Backward Stochastic Riccati Equation and a dual backward
stochastic equation, both considered in the whole time line. Besides some
stabilizability conditions we prove existence of a solution for the two
previous equations defined as limit of suitable finite horizon approximating
problems. This allows to perform the synthesis of the optimal control
Variable-step finite difference schemes for the solution of Sturm-Liouville problems
We discuss the solution of regular and singular Sturm-Liouville problems by
means of High Order Finite Difference Schemes. We describe a code to define a
discrete problem and its numerical solution by means of linear algebra
techniques. Different test problems are proposed to emphasize the behaviour of
the proposed algorithm
Building complex events: the case of Sicilian Doubly Inflected Construction
We examine the Doubly Inflected Construction of Sicilian (DIC; Cardinaletti and Giusti 2001, 2003, Cruschina 2013), in which a motion verb V1 from a restricted set is followed by an event verb V2 and both verbs are inflected for the same person and tense features. The interpretation of DIC involves a complex event which behaves as a single, integrated event by linguistic tests. Based on data drawn from different sources, we argue that DIC is an asymmetrical serial verb construction (Aikhenvald 2006). We propose an analysis of DIC in which V1 and V2 enter the semantic composition as lexical verbs, with V1 contributing a motion event and projecting a theme and a goal argument which are identified, respectively, with an agent and a location argument projected by V2. A morphosyntactic mechanism of feature-spread requires that the person and tense features be realized both on V1 and on V2, while, semantically, these features are interpreted only once, in a position from which they take scope over the complex predicate resulting from the combination of V1 and V2. The semantic analysis is based on an operation of event concatenation, defined over spatio-temporally contiguous events which share specific participants, and is implemented in a neo-Davidsonian framework (Parsons 1990)
Methods and Techniques for Quali-Quantitative Analyses: an Agricultural Application
[En] This paper describes a dynamic systems model which links the private and public functions of agriculture with the territorial development of rural regions and quality of life of rural residents. Among the key results are the quantification of a set of economic, social and environmental outcomes which follow from a set of EU policy scenarios for the period 2013. [It] L’articolo descrive un modello dinamico di sistema che lega le funzioni private e pubbliche dell’agricoltura con lo sviluppo territoriale delle regioni rurali e con la qualità della vita dei residenti. Tra i risultati principali vi è la quantificazione degli effetti economici, sociali e ambientali generati da un insieme di scenari di politiche comunitarie per il 2013. [Fr] L’article décrit un modèle dynamique de système qui lie les fonctions privées et publiques de l'agriculture avec le développement territorial des régions rurales et avec la qualité de la vie des résidants. Parmi les résultats principaux on a la quantification des effets sociaux, environnementaux et économiques générés par un ensemble de scénarios de politiques pour le 2013.POMMARD, Dynamic Systems Model, Multifunctional Agriculture, Rural Development, Quality of Life, Policies
A knowledge hub to enhance the learning processes of an industrial cluster
Industrial clusters have been defined as ?networks of production of strongly interdependent firms (including specialised suppliers), knowledge producing agents (universities, research institutes, engineering companies), institutions (brokers, consultants), linked to each other in a value adding production chain? (OECD Focus Group, 1999). The industrial clusters distinctive mode of production is specialisation, based on a sophisticated division of labour, that leads to interlinked activities and need for cooperation, with the consequent emergence of communities of practice (CoPs). CoPs are here conceived as groups of people and/or organisations bound together by shared expertise and propensity towards a joint work (Wenger and Suyden, 1999). Cooperation needs closeness for just-in-time delivery, for communication, for the exchange of knowledge, especially in its tacit form. Indeed the knowledge exchanges between the CoPs specialised actors, in geographical proximity, lead to spillovers and synergies. In the digital economy landscape, the use of collaborative technologies, such as shared repositories, chat rooms and videoconferences can, when appropriately used, have a positive impact on the development of the CoP exchanges process of codified knowledge. On the other end, systems for the individuals profile management, e-learning platforms and intelligent agents can trigger also some socialisation mechanisms of tacit knowledge. In this perspective, we have set-up a model of a Knowledge Hub (KH), driven by the Information and Communication Technologies (ICT-driven), that enables the knowledge exchanges of a CoP. In order to present the model, the paper is organised in the following logical steps: - an overview of the most seminal and consolidated approaches to CoPs; - a description of the KH model, ICT-driven, conceived as a booster of the knowledge exchanges of a CoP, that adds to the economic benefits coming from geographical proximity, the advantages coming from organizational proximity, based on the ICTs; - a discussion of some preliminary results that we are obtaining during the implementation of the model.
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