307 research outputs found
A Regulatory Impact Analysis (RIA) approach based on evolutionary association patterns
The present paper focuses on ex post analysis to asses the impact of an adopted policy by measuring system performance. Since accurate impact assessment requires in-depth knowledge of the structure underlying the system, this contribution proposes a suitable use of multidimensional data analysis (MDA) to investigate the associations characterizing the indicators/attributes of the system. The general aim is to identify homogeneous subsets of objects that are described by subsets of attributes. This approach was planned to study students performance in Italian universities: the focus is on student careers. The example data set is a data mart selected from the University of Macerata data base and refers to the students at the Economics Faculty from 2001 to 2007
Combined use of volumetric expanders and Scheffler receivers to improve the efficiency of a novel direct steam solar power plant
This research proposes an innovative solar thermal plant able to generate mechanical power through an optimized system of heliostats with Scheffler-type solar receivers coupled with screw-type steam expanders. Scheffler receivers appear to perform better than parabolic trough collectors due to the high compactness of the focal receiver, which minimizes convective and radiative heat losses even at high vaporization temperatures. At the same time, steam screw expanders are volumetric machines that can be used to produce mechanical power with satisfactory efficiency also by admitting two-phase mixtures and with further advantages compared to steam turbines: low working fluid velocities, low operating pressures, and avoidance of overheating. This study establishes a mathematical model to assess the energetic advantages of the planned solar thermal power system by evaluating the solar-to-electricity efficiency for different off-design working conditions. For this purpose, a numerical model on the Scheffler receiver is initially investigated, thus assessing all the energy losses which affect the heat transfer phase. A thermodynamic model is then developed to evaluate the energy losses and performance of the screw expander under real working conditions. Finally, parametric optimization of the solar energy conversion is performed in a wide range of operating conditions by establishing thermodynamic formulations related to the whole solar electricity generation system. Water condensation pressure and vaporization temperature are so optimized with respect to global energy conversion efficiency which, under the best operating conditions achieved in this research, rises from 10.9% to 14.4% with increasing solar irradiation intensity. Hence, the combined use of screw expanders and Scheffler receivers for solar thermal power system application can be a promising technology with advantages over parabolic dish concentrators. Novelty statement: This research proposes an innovative direct steam solar power plant based on an SRC, with water utilized as both heat transfer and working fluid, equipped with Scheffler solar receivers as a thermal source and screw expanders as work-producing devices. Technical studies and energy assessments of this kind of SEGS at part-load operation do not exist in scientific literature; after reviewing the literature, it was determined that volumetric expanders have been rarely combined with Scheffler receivers for solar thermal power system application. In effect, combined use of screw expanders and Scheffler-type solar concentrator in a direct steam solar power system represents a completely new plant configuration; however, as a promising DSG solar system, at present numerical model of this new sort of SEGS is lacked in literature and the optimum operating conditions have yet to be defined. For this reason, the chief objective of this paper is to define a first parametric optimization of all thermodynamic variables involved to maximize global efficiency of the proposed solar thermal power generation system for ordinary working conditions
Interview mit Alberto Bevilacqua über Namen
This is the fifth in a series of interviews with Italian writers on literary names. The purpose of this series is to complement the indirect approach of investigating strategies of literary naming in literary texts by directly questioning those who give names to literary characters or places. The interviews are to provide evidence of tendencies in literary naming in contemporary Italian writers. General conclusions will in due course be drawn from the material to be presented in the series. The present interview with Alberto Bevilacqua was conducted in Rome on 17 January 2003
Learning Cooperative Dynamic Manipulation Skills from Human Demonstration Videos
This article proposes a method for learning and robotic replication of
dynamic collaborative tasks from offline videos. The objective is to extend the
concept of learning from demonstration (LfD) to dynamic scenarios, benefiting
from widely available or easily producible offline videos. To achieve this
goal, we decode important dynamic information, such as the Configuration
Dependent Stiffness (CDS), which reveals the contribution of arm pose to the
arm endpoint stiffness, from a three-dimensional human skeleton model. Next,
through encoding of the CDS via Gaussian Mixture Model (GMM) and decoding via
Gaussian Mixture Regression (GMR), the robot's Cartesian impedance profile is
estimated and replicated. We demonstrate the proposed method in a collaborative
sawing task with leader-follower structure, considering environmental
constraints and dynamic uncertainties. The experimental setup includes two
Panda robots, which replicate the leader-follower roles and the impedance
profiles extracted from a two-persons sawing video
Correction of multiple canine impactions by mixed straightwire and cantilever mechanics: a case report.
Background. This case report describes the orthodontic treatment of a woman, aged 17 years, with a permanent dentition, brachyfacial typology, Angle Class I, with full impaction of two canines (13,33), and a severe ectopy of the maxillary left canine. Her main compliant was the position of the ectopic teeth. Methods. Straightwire fixed appliances, together with cantilever mechanics, were used to correct the impaired occlusion and to obtain an ideal torque control. Results and Conclusion. The treatment objectives were achieved in 26 months of treatment. The impactions were fully corrected with an optimal torque. The cantilever mechanics succeeded in obtaining tooth repositioning in a short lapse of time. After treatment, the dental alignment was stable
Association between work related stress and health related quality of life: the impact of socio-demographic variables. A cross sectional study in a region of central Italy
The aim of this work is investigate relationship between health-related quality of life and work-related stress and the impact of gender, education level, and age on this relationship. A cross-sectional study was conducted among workers of various setting in Rome and Frosinone. Work-related stress was measured with a demand-control questionnaire and health-related functioning by SF (short form)-12 health survey. There were 611 participants. Men reported high mental composite summary (MCS) and physical composite summary (PCS). In multivariate analysis age, gender (p < 0.001) and job demand (0.045) predicted low PCS. Low MCS predicted poor PCS. Job demand and educational level resulted negatively associated with MCS. In an analysis stratified for age, gender, and educational level, gender and age resulted effect modifier for MCS, gender and education level for PCS. In women increase of decision latitude predict (p = 0.001) an increase in MCS; a low job demand predict high MCS in male (p ≤ 0.001). In younger workers, a lower level of job demand predicted high MCS (<0.001). For PCS, gender and education level resulted effect modifier. In women, high decision latitude predicted higher PCS (p = 0.001) and lower level of job demand results in higher PCS (p ≤ 0.001). Higher educational level resulted predictor of low PCS. Management of risk about work-related stress should consider socio-demographic factors
Hydrological modeling in ungauged basins using SAR data
In this paper we propose a methodology devoted to exploit high resolution radars for monitoring water bodies in semi-arid countries. The proposed approach is based on appropriate registration, calibration and processing of SAR data, producing information ready to use by end-users. The obtained results were used to (i) estimate a relationship between surface and volume of water stored in reservoirs and (ii) validate a hydrological model that simulates the time evolution of water availability
Modeling Watershed Response in Semiarid Regions With High-Resolution Synthetic Aperture Radars
In this paper, we propose a methodology devoted to exploit the outstanding characteristics of COSMO-SkyMed for monitoring water bodies in semiarid countries at a scale never experienced before. The proposed approach, based on appropriate registration, calibration, and processing of synthetic aperture radar (SAR) data, allows outperforming the previously available methods for monitoring small reservoirs, mainly carried out with optical data, and severely limited by the presence of cloud coverage, which is a frequent condition in wet season. A tool has been developed for computing the water volumes retained in small reservoirs based on SAR-derived digital elevation model. These data have been used to derive a relationship between storage volumes and surface areas that can be used when bathymetric information is unavailable. Due to the lack of direct measures of river's discharge, the time evolution of water volumes retained at reservoirs has been used to validate a simple rainfall-runoff hydrological model that can provide useful recommendation for the management of small reservoirs. Operational scenarios concerning the improvement in the efficiency of reservoirs management and the estimation of their impact on downstream area point out the applicative outcomes of the proposed method
Telemedicine in Parkinson's Disease: How to Ensure Patient Needs and Continuity of Care at the Time of COVID-19 Pandemic
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