Search results for "Diss"

La rilevazione della soddisfazione e dell’insoddisfazione dei turisti: una proposta operativa.

2013

Retrieval of Case 2 Water Quality Parameters with Machine Learning

2018

Water quality parameters are derived applying several machine learning regression methods on the Case2eXtreme dataset (C2X). The used data are based on Hydrolight in-water radiative transfer simulations at Sentinel-3 OLCI wavebands, and the application is done exclusively for absorbing waters with high concentrations of coloured dissolved organic matter (CDOM). The regression approaches are: regularized linear, random forest, Kernel ridge, Gaussian process and support vector regressors. The validation is made with and an independent simulation dataset. A comparison with the OLCI Neural Network Swarm (ONSS) is made as well. The best approached is applied to a sample scene and compared with t…

Retrieval of coloured dissolved organic matter with machine learning methods

2017

The coloured dissolved organic matter (CDOM) concentration is the standard measure of humic substance in natural waters. CDOM measurements by remote sensing is calculated using the absorption coefficient (a) at a certain wavelength (e.g. 440nm). This paper presents a comparison of four machine learning methods for the retrieval of CDOM from remote sensing signals: regularized linear regression (RLR), random forest (RF), kernel ridge regression (KRR) and Gaussian process regression (GPR). Results are compared with the established polynomial regression algorithms. RLR is revealed as the simplest and most efficient method, followed closely by its nonlinear counterpart KRR.

Classical and Quantum Annealing in the Median of Three Satisfiability

2011

We determine the classical and quantum complexities of a specific ensemble of three-satisfiability problems with a unique satisfying assignment for up to N = 100 and 80 variables, respectively. In the classical limit, we employ generalized ensemble techniques and measure the time that a Markovian Monte Carlo process spends in searching classical ground states. In the quantum limit, we determine the maximum finite correlation length along a quantum adiabatic trajectory determined by the linear sweep of the adiabatic control parameter in the Hamiltonian composed of the problem Hamiltonian and the constant transverse field Hamiltonian. In the median of our ensemble, both complexities diverge e…

Nonlinear quantum Langevin equations for bosonic modes in solid-state systems

2017

Based on the experimental evidence that impurities contribute to the dissipation properties of solid-state open quantum systems, we provide here a description in terms of nonlinear quantum Langevin equations of the role played by two-level systems in the dynamics of a bosonic degree of freedom. Our starting point is represented by the description of the system/environment coupling in terms of coupling to two separate reservoirs, modelling the interaction with external bosonic modes and two level systems, respectively. Furthermore, we show how this model represents a specific example of a class of open quantum systems that can be described by nonlinear quantum Langevin equations. Our analysi…

Cross-sublattice Spin Pumping and Magnon Level Attraction in van der Waals Antiferromagnets

2020

We theoretically study spin pumping from a layered van der Waals antiferromagnet in its canted ground state into an adjacent normal metal. We find that the resulting dc spin pumping current bears contributions along all spin directions. Our analysis allows for detecting intra- and cross-sublattice spin-mixing conductances via measuring the two in-plane spin current components. We further show that sublattice symmetry-breaking Gilbert damping can be realized via interface engineering and induces a dissipative coupling between the optical and acoustic magnon modes. This realizes magnon level attraction and exceptional points in the system. Furthermore, the dissipative coupling and cross-subla…

Faraday patterns in bose-Einstein condensates.

2002

Temporal periodic modulation of the interatomic s-wave scattering length in Bose-Einstein condensates is shown to excite subharmonic patterns of atom density through a parametric resonance. The dominating wavelength of the spatial structures is shown to be primarily selected by the excitation frequency but also affected by the depth of the spatial modulation via a nonlinear resonance. These phenomena represent macroscopic quantum analogues of the Faraday waves excited in vertically shaken liquids.

What is the role of social media in several overtones of CSR communication? The case of the wine industry in the Southern Italian regions

2019

Purpose The purpose of this paper is to understand whether the companies most involved in communicating their responsible behaviour externally are those most active on the social media (SM) platform, with a philanthropic purpose rather than strictly aimed at economic aspects. Design/methodology/approach The authors, first, assess firms’ efforts on the SM platform using the model proposed by Chung et al. (2014), and, second, the authors analyze the content of messages in order to verify what dimensions of the corporate social responsibility (CSR) they contain. A multivariate modelling has been performed in order to verify whether the wineries that take most care to communicate their respons…

How, Why and with Whom Do Local Politicians Engage on Facebook?

2013

Part 2: Social Media and E-Participation; International audience; This article focuses on how, why and with whom local politicians engage on Facebook. Based on a literature review of the public sphere, eParticipation and research related to social media, we propose a theoretical framework that identifies thematic areas integral to understanding the nature of political participation. The explanatory potential of our ‘ENGAGE’ model (Exchange, Narcissist, Gather, Accented, General and Expense) is exemplified by conducting a qualitative case study focusing on politicians in a local municipality in southern Norway. The findings indicate various uses of Facebook among the respondents, and a disso…

Long Term Results After Repair of Type A Acute Aortic Dissection According to False Lumen Patency.

2009

Background. Late survival and freedom from retreatment on the descending aorta was evaluated after ascending aortic repair for type A acute aortic dissection (TAAAD). Methods. Between March 1992 and January 2006, 189 TAAAD patients (mean age, 52 11; range, 17 to 83 years) were included; of these, 58 had a patent false lumen, and 49 had Marfan syndrome. The descending aorta was evaluated postoperatively with computed tomography (CT). Late outcomes were assessed by Cox regression analysis and actuarial survival and freedom from retreatment by the Kaplan-Meier method. Mean follow-up was 88 44 months. Results. There were 38 (20%) late deaths. At 10 years, survival was 89.8% 2.1% for patients wi…