Search results for "Estimation"
showing 10 items of 924 documents
Temporal-range estimation of multiple objects: evidence for an early bottleneck.
2011
When making parallel time-to-contact (TTC) estimates of two approaching objects, the two respective TTC estimates interfere with one another in an asymmetric fashion. The TTC of the later-arriving object is systematically overestimated, while the estimated TTC for the first-arriving object is as accurate as in a condition presenting only a single object. This asymmetric interference points to a processing bottleneck that could be due to early (e.g., during the estimation of the TTC from the optic flow) or late (e.g., during the timing of the response or the motor execution) constraints in the TTC estimation process. We used a Sperling-like prediction-motion task to differentiate between the…
Simulation d'images d'un futur imageur multispectral géostationaire dédié à la couleur de l'eau : étude de l'influence des angles d'observation et d'…
2011
Improvements of optical sensors now make it possible to launch medium spatial and high spectral resolution sensors on the Geostationary Earth Orbit (GEO). The GEO allows sensors to observe the Earth with high temporal resolution, unlike Low Earth Orbit (LEO) satellites. The objective of this thesis is to simulate radiance images that would be provided by a theoretical ocean color sensor, on a geostationary orbit, in order to characterize the images to be acquired, to specify the future instruments and to validate the image processing algorithms. For this purpose, we have combined a radiative transfer model for ocean waters (Hydrolight) and a radiative transfer model for the atmosphere (MODT…
Localisation basée vision à partir de caractéristiques discriminantes issues de données visuelles hétérogènes
2019
Visual-based Localization (VBL) consists in retrieving the location of a visual image within a known space. VBL is involved in several present-day practical applications, such as indoor and outdoor navigation, 3D reconstruction, etc. The main challenge in VBL comes from the fact that the visual input to localize could have been taken at a different time than the reference database. Visual changes may occur on the observed environment during this period of time, especially for outdoor localization. Recent approaches use complementary information in order to address these visually challenging localization scenarios, like geometric information or semantic information. However geometric or sema…
Extrapolation of the Species Accumulation Curve for Incomplete Species Samplings: A New Nonparametric Approach to Estimate the Degree of Sample Compl…
2015
9 pages; International audience; Incomplete species samplings are deemed to remain the common practice in those groups of animals, such as small or micro- invertebrates, with numerous species that often are more or less difficult to detect in the field. Thus, extrapolating the Species Accumulation Curve as far as possible beyond the actual sample size may thus serve as a useful (although imperfect) surrogate to the desired, but practically inaccessible, complete samplings. In this context, several kinds of theoretical or empirical models for the Species Accumulation Curve and also a lot of estimators of the asymptotic limit of the Curve (i.e. total species richness) have been proposed. The …
Goodness-of-fit tests for parametric excess hazard rate models with covariates
2017
In this paper we propose a general methodology for testing the null hypothesis that an excess hazard rate model, with or without covariates, belongs to a parametric family. Estimating the excess hazard rate function parametrically through the maximum likelihood method and non-parametrically (or semi-parametrically) we build a discrepancy process which is shown to be asymptotically Gaussian under the null hypothesis. Based on this result we are able to build some statistical tests in order to decide wether or not the null hypothesis is acceptable. We illustrate our results by the construction of chi-square tests which the behavior is studied through a Monte-Carlo study. Then the testing proc…
Joint Optimization of Sensor Selection and Routing for Distributed Estimation in Wireless Sensor Networks
2014
Avances recientes en redes inalámbricos de sensores (WSNs, Wireless Sensor Networks) han posibilitado que pequeños sensores, baratos y con recursos limitados tanto en sensado, comunicación, como en computación, sean desplegados a gran escala. En consecuencia, las WSNs pueden ofrecer diversos servicios en importantes aplicaciones para la sociedad. Entre las varias restricciones que aparecen en el diseño de WSNs, tales como la limitación en energía disponible, procesamiento y memoria, la limitación en energía es muy importante ya que en muchas aplicaciones (ej., monitorización remota de diferentes entornos, edificios administrativos, monitoreo del hábitat, los incendios forestales, la atenció…
A Bayesian Reconstruction of a Historical Population in Finland, 1647–1850
2020
This article provides a novel method for estimating historical population development. We review the previous literature on historical population time-series estimates and propose a general outline to address the well-known methodological problems. We use a Bayesian hierarchical time-series model that allows us to integrate the parish-level data set and prior population information in a coherent manner. The procedure provides us with model-based posterior intervals for the final population estimates. We demonstrate its applicability by estimating the long-term development of Finlands population from 1647 onward and simultaneously place the country among the very few to have an annual popula…
Forecasting Passenger Traffic for a Regional Airport
2019
Abstract The purpose of the present research is estimating the potential traffic for SIA (Sibiu International Airport, SBZ) for the year 2017. Predicting as accurate as possible the passenger traffic for a certain airport is an aspect of major importance for both the airport management and the airline companies. The theoretical quality of the forecasting models for air traffic of passengers is fundamental for obtaining the most accurate predictions. In this regard, a two-step process was used in developing the traffic forecasting model: (1) Identifying the proper regression model for traffic estimation based on the number of aircraft departures, and (2) Forecasting the number of aircraft de…
Explaining information technology users’ ways of mitigating technostress
2017
Technostress refers to the inability of an individual to deal with information technology (IT) in a healthy manner. Researchers, practitioners, and medical professionals have emphasized the omnipresence of technostress and its severe outcomes, including poor well-being and burnout. Despite the importance of the phenomenon, prior research has paid limited attention to how technostress can be mitigated. The few existing studies examine organizational mitigation mechanisms, but we could not find any studies that focus on individual IT users’ own ways of mitigating technostress outside of work. To address the research gap, we conducted a qualitative study to uncover users’ ways of mitigating te…
The Effect of Textual Producer-Generated Descriptions on Demand of Mobile Applications
2017
We analyze the impact of different app description characteristics on app demand on the basis of panel data for six months and 1081 distinct apps. We use several text mining techniques in order to operationalize the descriptions’ textual characteristics. The extracted variables are then used in an econometric investigation to examine their impact on apps’ downloads. Our results provide evidence that app descriptions have an effect on demand. Apps with upfront price should be described in a neutral tone. Apps without an upfront price but with in-app purchase option should be offered with rather short descriptions that are written in a formal and subjective style. peerReviewed