Search results for "variance"

showing 10 items of 2030 documents

Improving Harris corner selection strategy

2011

This study describes a corner selection strategy based on the Harris approach. Corners are usually defined as interest points for which intensity variation in the principal directions is locally maximised, as response from a filter given by the linear combination of the determinant and the trace of the autocorrelation matrix. The Harris corner detector, in its original definition, is only rotationally invariant, but scale-invariant and affine-covariant extensions have been developed. As one of the main drawbacks, corner detector performances are influenced by two user-given parameters: the linear combination coefficient and the response filter threshold. The main idea of the authors' approa…

Settore INF/01 - Informaticabusiness.industryAutocorrelationDetectorCorner detectionGeometryScale invarianceEdge detectionAutocorrelation matrixComputer Vision and Pattern RecognitionArtificial intelligenceInvariant (mathematics)Linear combinationbusinessAlgorithmSoftwareMathematicsHarris corner detector
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Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

2012

Settore ING-INF/03 - TelecomunicazioniFree Space Optics (FSO) technologies for satellite communications offer several advantages: wide bandwidth high rate capability immunity to electromagnetic interference and small equipment size. Thus they are suitable for inter-satellite links deep space communications and also for high data rate ground-to-satellite/satellite-to-ground communications. Nevertheless FSO links suffer impairments that cause power signal degradation at the receiver. Scattering and absorption cause power signal attenuations predictable by suitable deterministic models. Optical turbulence causes random irradiance fluctuations which can generate signal fading events and can thereby only be predicted by statistical models. Attenuation and fading events can corrupt FSO links and so it would be recommended to add mitigation error codes on the communication link. FSO channel can be described as an erasure channel: fading events can cause erasure errors. We have identified in rateless codes (RCs) a suitable solution to be employed in FSO links. RCs do not need feedback and they add a redundant coding on the source data that allows the receiver to recover the whole payload despite erasure errors. We implemented two different of rateless codes: Luby Transform (LT) and Raptor. We analyzed their performances on a simulated turbulent GEO FSO downlink (1 Gbps - OOK modulation) at a 106 μm wavelength and for different values of zenith angles. Assuming a plane-wave propagation and employing Hufnagel-Valley we modeled the downlink using: 1) a temporal correlated channel model based on Gamma-Gamma probability distribution and 2) an irradiance covariance function that we converted on a time function using Taylor frozen eddies hypothesis. Our new channel model is able to simulate irradiance fluctuations at different turbulence conditions as it will be shown in the full paper. We will also report performance results of LT and Raptor codes at overhead range varying between 0 and 50% and for different values of source packets.Settore ING-INF/01 - Elettronica
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Perceptual Social Dimensions of Human - Humanoid Robot Interaction

2013

The present paper aims at a descriptive analysis of the main perceptual and social features of natural conditions of agent interaction, which can be specified by agent in human-humanoid robot interaction. A principled approach to human-robot interaction may be assumed to comply with the natural conditions of agents overt perceptual and social behaviour. To validate our research we used the minimalistic humanoid robot Telenoid. We have conducted human-robot interactions test with people with no prior interaction experience with robot. By administrating our questionnaire to subject after well defined experimental conditions, an analysis of significant variance correlation among dimensions in …

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniCommunicationComputer sciencebusiness.industrymedia_common.quotation_subjectAutonomous agentVariance (accounting)Social relationHuman–robot interactionHuman–computer interactionPerceptionTeleoperationRobotbusinessHumanoid robotmedia_common
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The Italian version of the Cognitive Style Indicator and its association with decision-making preferences

2018

By adopting a more flexible view, Cools and Van den Broeck (2007) developed the Cognitive Style Indicator (CoSI) which includes three cognitive dimensions: Creating (flexible, open-ended and inventive), Knowing (emphasizing facts, details, objectivity, and rationality), and Planning (guided by preferences for certainty and well-structured information). The first aim of this research was to validate the three factor structure of the CoSI within the Italian context, whereas the second was to verify whether cognitive styles, as measured by the CoSI, accounted for individual differences in decision-making processes. Two studies were conducted using two different samples (n = 549 and n = 397). C…

Settore M-PSI/01 - Psicologia GeneraleCognitive styleVisual Arts and Performing Arts05 social sciencesConstruct validity050109 social psychologyRationalityTest validity050105 experimental psychologyStructural equation modelingFactorial structureCognitive dimensions of notationsDevelopmental and Educational Psychology0501 psychology and cognitive sciencesMeasurement invariancePsychology (miscellaneous)PsychologyObjectivity (science)Cognitive psychologyCognitive styleDecision-making
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Cognitive vulnerability to depressive symptoms in children: the protective role of self-efficacy beliefs in a multi-wave longitudinal study.

2014

The current multi-wave longitudinal study on childhood examined the role that social and academic self-efficacy beliefs and cognitive vulnerabilities play in predicting depressive symptoms in response to elevations in idiographic stressors. Children (N = 554; males: 51.4 %) attending second and third grade completed measures of depressive symptoms, negative cognitive styles, negative life events, and academic and social self-efficacy beliefs at four time-points over 6 months. Results showed that high levels of academic and social self-efficacy beliefs predicted lower levels of depressive symptoms, whereas negative cognitive styles about consequences predicted higher depression. Furthermore,…

Settore M-PSI/01 - Psicologia GeneraleMaleLongitudinal studyPoison controlDysfunctional familySelf-efficacy beliefsDepression; Self-efficacy beliefs; Cognitive styles; Hassles; Childhood;ArticleDevelopmental psychologyLife Change EventsCognitionPredictive Value of TestsDevelopmental and Educational PsychologyHumansInterpersonal RelationsLongitudinal StudiesChildCognitive stylesSelf-efficacyCognitive vulnerabilityAnalysis of VarianceDepressive DisorderDepressionHuman factors and ergonomicsCognitionChildhoodSelf EfficacyPsychiatry and Mental healthItalyEducational StatusFemaleHasslesDepression Self-efficacy beliefs Cognitive styles Hassles ChildhoodPsychologyStress PsychologicalCognitive styleClinical psychologyJournal of abnormal child psychology
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Measurement invariance of the nine-item Internet Gaming Disorder Scale (IGDS9-SF) across Albania, USA, UK, and Italy

2018

The IGDS9-SF, which assesses Internet Gaming Disorder behaviors, has been validated in a number of countries (Portugal, Italy, Iran, Slovenia), although the psychometric equivalence of the instrument has been assessed only across Australia, the USA, the UK, and India. This research aimed at providing further cross-cultural insights into IGD by assessing the factorial structure of the IGDS9-SF in Albania and investigating its measurement invariance across Albanian, Italian, American, and British gamers. Multi-Group Confirmatory Factor Analyses were performed on a sample of 1411 participants from Albania (n = 228), USA (n = 237), the UK (n = 275), and Italy (n = 671). The CFAs confirmed the s…

Settore M-PSI/01 - Psicologia GeneraleVideo gamingbusiness.industry030508 substance abusePsychometric equivalencemanop030227 psychiatry03 medical and health sciencesPsychiatry and Mental healthHealth psychology0302 clinical medicineScale (social sciences)Internet Gaming Disorder.Gaming addiction.Video gaming.IGDS9-SF.Cross-cultural validation.Measurement invarianceThe InternetMeasurement invarianceMetric (unit)0305 other medical sciencebusinessPsychologyClinical psychology
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Measuring dispositional optimism in patients with chronic heart failure and their healthcare providers: The validity of the Life Orientation Test-Rev…

2017

Patrizia Steca,1 Dario Monzani,1 Antonia Pierobon,2 Giulia Avvenuti,2 Andrea Greco,1 Anna Giardini2 1Department of Psychology, University of Milano – Bicocca, Milan, 2Psychology Unit, Istituti Clinici Scientifici Maugeri Spa SB, IRCCS Montescano, Montescano, Italy Abstract: The Life Orientation Test-Revised (LOT-R) measures dispositional optimism (DO) – an individual difference promoting physical and psychological well-being in healthy adults (HAs) as well as in patients with chronic heart failure (CHF) and healthcare providers (HPs). Controversy has arisen regarding the dimensionality of the LOT-R. Whereas DO was originally defined as a one-dimensional construct, empiri…

Settore M-PSI/01 - Psicologia Generalemedicine.medical_specialtyvalidityMedicine (miscellaneous)Dispositional optimismLife Orientation Test-Revised050109 social psychology050105 experimental psychologymedicine0501 psychology and cognitive sciencesIn patientMeasurement invariancecardiovascular diseasesPsychiatryPharmacology Toxicology and Pharmaceutics (miscellaneous)Depression (differential diagnoses)Original ResearchLife Orientation Test-Revised; dispositional optimism; validity; measurement equivalence; chronic heart failurelcsh:R5-920business.industryHealth Policy05 social sciencesdispositional optimismLife Orientation Test – Revisedmedicine.diseaseDifferential item functioningConfirmatory factor analysishumanitieschronic heart failurePatient Preference and AdherenceHeart failureAnxietymedicine.symptomlcsh:Medicine (General)businessmeasurement equivalenceSocial Sciences (miscellaneous)Clinical psychology
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Form constancy

2020

Form constancy denotes the appearance of the invariant shape of objects in the environment, notwithstanding the variability due to changes of the viewpoint, caused by subjects movement, to objects displacement, to illumination, lightness, color, and texture whose variation can affect the internal and external boundaries of the surfaces that fall in the simultaneous or successive views of solid objects. In early psychology of perception, shape invariance was called form constancy to highlight the perceptual ability to derive something constant from the changing forms of the multiple views of objects. Shape is an attribute of 2D surfaces and 3D objects, which are invariant across the transfor…

Settore M-PSI/01 - Psicologia Generaleshape form invariance perception visionSettore M-FIL/04 - Estetica
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Multiple solutions with sign information for a (p,2)-equation with combined nonlinearities

2020

We consider a parametric nonlinear Dirichlet problem driven by the sum of a p-Laplacian and of a Laplacian (a (p,2)-equation) and with a reaction which has the competing effects of two distinct nonlinearities. A parametric term which is (p−1)-superlinear (convex term) and a perturbation which is (p−1)-sublinear (concave term). First we show that for all small values of the parameter the problem has at least five nontrivial smooth solutions, all with sign information. Then by strengthening the regularity of the two nonlinearities we produce two more nodal solutions, for a total of seven nontrivial smooth solutions all with sign informations. Our proofs use critical point theory, critical gro…

Settore MAT/05 - Analisi MatematicaConstant sign and nodal solutionFlow invarianceConvex–concave problemStrong comparison principleCritical groupNonlinear regularity
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Wavelet Analysis Of Variance Risk Premium Spillovers

2013

In this paper we construct a variance risk premium spillover index among France, Germany, UK, Switzerland and the US. The variance risk premium is measured by the difference between the difference between the (square) of implied volatility and expected realized variance of the stock market for next month. We also construct a spillover index for the constituents of the variance risk premium. The series under investigation exhibit long memory properties. The construction of a total spillover indicator suggested by Diebold-Yilmaz (2009) would then rely on modeling a fractionally integrated Vector Autoregressive Model, which might be subject to errors in specifying the correct lag length and th…

Settore SECS-P/05 - Econometriavariance risk premium implied variance realized variance long memory MODWT spillover index
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