Search results for " estimation"

A Channel-Aware Adaptive System for Underwater Acoustic Communications

2021

In recent years, underwater communications have seen a growing interest pushed by marine research, oceanography, marine commercial operations, offshore oil industry and defense applications. Generally, underwater communications employ audio signals which can propagate relatively far. However, acoustic underwater channels are very challenging, because of limited bandwidth, long propagation delays, extended multipath, severe attenuation, rapid time variation and large Doppler shifts. A plethora of underwater communication techniques have been developed for dealing with such a complexity, mostly tailoring specific applications scenarios which can not be considered as one-size-fits-all solution…

LES DISCRIMINATIONS A L'EMBAUCHE DANS LA SPHERE PUBLIQUE : EFFETS RESPECTIFS DE L'ADRESSE ET DE L'ORIGINE

2016

Cette étude évalue la discrimination dans l’accès à l’emploi dans trois professions présentes à la fois dans le secteur privé et dans la Fonction Publique. Deux dimensions sont examinées : l’effet de la réputation du lieu de résidence et l’effet de l’origine maghrébine. Elle est réalisée sur données expérimentales de testing réalisé dans trois professions en tension pour lesquelles la discrimination devrait a priori être très réduite : les responsables administratifs de catégorie A, les techniciens de maintenance de catégorie B et les aides soignantes de catégorie C. Pour chaque profession, nous avons construit 3 profils fictifs de candidats à l’emploi similaires en tout point à l’exception…

Job Satisfaction among Primary School Personnel

2016

International audience; This article analyzes the job satisfaction of primary school teachers inMadagascar. Based on the estimation of multilevel models, low wages and problems getting paid, job insecurity, lack of in-service training, high pupil-teacher ratios, and lack of basic infrastructure and teaching materials are identified as the main reasons for dissatisfaction. Principals' control of teachers' activities also adversely affects satisfaction, suggesting that, in Malagasy schools, neither school directors nor teachers have succeeded in adopting organizational cultures based on cooperation among their members. These results are likely to stimulate debates on educational policy, both …

Localization in Structured Environments with UWB Devices without Acceleration Measurements, and Velocity Estimation Using a Kalman–Bucy Filter

2022

In this work, a novel scheme for velocity and position estimation in a UWB range-based localization system is proposed. The suggested estimation strategy allows to overcome two main problems typically encountered in the localization systems. The first one is that it can be suitable for use in environments where the GPS signal is not present or where it might fail. The second one is that no accelerometer measurements are needed for the localization task. Moreover, to deal with the velocity estimation problem, a suitable Kalman–Bucy filter is designed and it is compared, experimentally, with a particle filter by showing the features of the two algorithms in order to be used in a localization …

Kernel estimation and display of a five-dimensional conditional intensity function

2018

The aim of this paper is to find a convenient and effective method of displaying some second order properties in a neighbourhood of a selected point of the process. The used techniques are based on very general high-dimensional nonparametric smoothing developed to define a more gen- eral version of the conditional intensity function introduced in earlier earthquake studies by Vere-Jones (1978). 1976) is commonly used for such a purpose in discussing the cumulative behavior of interpoint distances about an initial point. It is defined as the expected number of events falling within a given distance of the initial event, divided by the overall density (rate in 2-dimensions) of the process, sa…

Learning with the kernel signal to noise ratio

2012

This paper presents the application of the kernel signal to noise ratio (KSNR) in the context of feature extraction to general machine learning and signal processing domains. The proposed approach maximizes the signal variance while minimizes the estimated noise variance in a reproducing kernel Hilbert space (RKHS). The KSNR can be used in any kernel method to deal with correlated (possibly non-Gaussian) noise. We illustrate the method in nonlinear regression examples, dependence estimation and causal inference, nonlinear channel equalization, and nonlinear feature extraction from high-dimensional satellite images. Results show that the proposed KSNR yields more fitted solutions and extract…

Robust control in uncertain multi-inventory systems and consensus problems

2008

Abstract We consider a continuous time linear multi–inventory system with unknown demands bounded within ellipsoids and controls bounded within polytopes. We address the problem of ∈-stabilizing the inventory since this implies some reduction of the inventory costs. The main results are certain conditions under which ∈-stabilizability is possible through a saturated linear state feedback control. The idea of this approach is similar to the consensus problem solution for a network of continuous time dynamic agents, where each agent evolves according to a first order dynamics has bounded control and it is subject to unknown but bounded disturbances. In this context, we derive conditions under…

Expectations and the term premium as time varying leading indicators of US economic activity

2009

This paper investigates the growth predictive properties of the expectation-related and term premium components of the US term spread. Results suggest that although the predictive power of two components has greater predictive power compared to the simple spread, it has a time-varying nature. The expectations-related term is positive and statistically significant up to the end of the 80s becoming insignificant afterwards. The term-premium estimates are positive and significant for a brief period in the 70s, turn insignificant after the 80s, except in short intervals at the beginning of the 90s and the 2000s, when they turn negative.

Proterozoic dykes of Salvador and Ilhéus-Olivença areas: a geological geoghemical comparison

1991

Early assessment of crop yield from remotely sensed water stress and solar radiation data

2018

Soil moisture (SM) available for evapotranspiration is crucial for food security, given the significant interannual yield variability of rainfed crops in large agricultural regions. Also, incoming solar radiation (Rs) influences the photosynthetic rate of vegetated surfaces and can affect productivity. The aim of this work is to evaluate the ability of crop water stress and Rs remotely sensed data to forecast yield at regional scale. Temperature Vegetation Dryness Index (TVDI) was computed as an indicator of crop water stress and soil moisture availability. TVDI during critical growth stage of crops was calculated from MODIS products: MODIS/AQUA 8-day composite LST at 1 km and 16-day compos…