Search results for "Jacob"

Some Improvements on Relativistic Positioning Systems

2018

[EN] We make some considerations about Relativistic Positioning Systems (RPS). Four satellites are needed to position a user. First of all we define the main concepts. Errors should be taken into account. Errors depend on the Jacobian transformation matrix. Its Jacobian is proportional to the tetrahedron volume whose vertexes are the four tips of the receiver-satellite unit vectors. If the four satellites are seen by the user on a circumference in the sky, then, the Jacobian and the tetrahedron volume vanish. The users we consider are spacecraft. Spacecraft to be positioned cannot be close to a null Jacobian satellites-user configuration. These regions have to be avoided choosing an appropr…

Nonlocal discrete ∞-Poisson and Hamilton Jacobi equations

2015

In this paper we propose an adaptation of the ∞-Poisson equation on weighted graphs, and propose a finer expression of the ∞-Laplace operator with gradient terms on weighted graphs, by making the link with the biased version of the tug-of-war game. By using this formulation, we propose a hybrid ∞-Poisson Hamilton-Jacobi equation, and we show the link between this version of the ∞-Poisson equation and the adaptation of the eikonal equation on weighted graphs. Our motivation is to use this extension to compute distances on any discrete data that can be represented as a weighted graph. Through experiments and illustrations, we show that this formulation can be used in the resolution of many ap…

Hybrid WENO schemes for polydisperse sedimentation models

2015

International audience; Polydisperse sedimentation models can be described by a strongly coupled system of conservation laws for the concentration of each species of solids. Typical solutions for the sedimentation model considered for batch settling in a column include stationary kinematic shocks separating layers of sediment of different composition. This phenomenon, known as segregation of species, is a specially demanding task for numerical simulation due to the need of accurate numerical simulations. Very high-order accurate solutions can be constructed by incorporating characteristic information, available due to the hyperbolicity analysis made in Donat and Mulet [A secular equation fo…

Anxiety symptoms and mild cognitive impairment among community-dwelling older adults from low- and middle-income countries.

2021

Abstract Aim Anxiety may be a risk factor for mild cognitive impairment (MCI) but there is a scarcity of data on this association especially from low- and middle-income countries (LMICs). Thus, we investigated the association between anxiety and MCI among older adults residing in six LMICs (China, Ghana, India, Mexico, Russia, South Africa), and the mediational effect of sleep problems in this association. Methods Cross-sectional, community-based, nationally representative data from the WHO Study on global AGEing and adult health (SAGE) were analyzed. The definition of MCI was based on the National Institute on Ageing-Alzheimer's Association criteria. Multivariable logistic regression analy…

Relacion de la exemplar vida y muerte del Cauallero de Gracia

Esc. xil. de D. Diego Garcia Xalon de la Puente, a qui es dedica l'obra, a la port Errates tip. a la fol.: 312 per 132 Sign.: ¶4, A-Q8, R4

Brief an Garlieb H. Merkel

1798

Ms. 930a, Nr. 10, Bl. 26r-28v Schmidt-Phiseldeck, Konrad von. Brief an Garlieb H. Merkel, Kopenhagen, am 6. März 1798 Autora rokraksts / Autograph, vācu un latīņu val. / Deutsch und Latein [6] lpp. / S. Attēlu numuri / Bildnummern: 930a-010-1 – 930a-010-6 Der Verfasser äußert zum Beginn seines Briefes erneut sein Bedauern über die räumliche Trennung und wünscht sich, nach Italien zu reisen. Weimar, wo Merkel zum gegebenen Zeitpunkt wahrscheinlich weilte, glorifiziert Schmidt-Phiseldeck mit der Bezeichnung als „Weimar-Athen“. Gleichzeitig drückt der Verfasser seine Enttäuschung über die Politik Frankreichs bezüglich der Schweiz aus, erkennt aber in der Neutralität seiner neuen Heimat Dänemar…

Products of Bessel functions and associated polynomials

2013

The symbolic method is used to get explicit formulae for the products or powers of Bessel functions and for the relevant integrals.

Herodots Weltanschauung: ‘l’empirismo erodoteo’ di Eduard Meyer. Nota introduttiva e traduzione

2015

La Weltanschauung di Erodoto

2015

Locating Objects Away from Earth Surface: Positioning Accuracy

2013

The motion of the Galileo and GPS satellite constellations is simulated in Schwarzschild space-time, whereas photons travel in Minkowski space-time. This is a good enough approach to deal with the main goal of this paper: the study of positioning accuracy in the framework of the so-called relativistic positioning. Our study is based on numerical 4D simulations. In this meeting, the contribution of J.A. Morales-Lladosa contains some basic ideas which have been important to perform our numerical calculations. For four chosen emitters (satellites) of a certain constellation, many receivers located at different distances from Earth surface and in distinct directions are considered. Thus, we ver…