Search results for " Programming"
showing 10 items of 1616 documents
A Symplectic Kovacic's Algorithm in Dimension 4
2018
Let $L$ be a $4$th order differential operator with coefficients in $\mathbb{K}(z)$, with $\mathbb{K}$ a computable algebraically closed field. The operator $L$ is called symplectic when up to rational gauge transformation, the fundamental matrix of solutions $X$ satisfies $X^t J X=J$ where $J$ is the standard symplectic matrix. It is called projectively symplectic when it is projectively equivalent to a symplectic operator. We design an algorithm to test if $L$ is projectively symplectic. Furthermore, based on Kovacic's algorithm, we design an algorithm that computes Liouvillian solutions of projectively symplectic operators of order $4$. Moreover, using Klein's Theorem, algebraic solution…
LOFT: the Large Observatory For X-ray Timing
2012
The LOFT mission concept is one of four candidates selected by ESA for the M3 launch opportunity as Medium Size missions of the Cosmic Vision programme. The launch window is currently planned for between 2022 and 2024. LOFT is designed to exploit the diagnostics of rapid X-ray flux and spectral variability that directly probe the motion of matter down to distances very close to black holes and neutron stars, as well as the physical state of ultra-dense matter. These primary science goals will be addressed by a payload composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a collimated (<1 degree field of view) experiment operating in the energy range 2-50 keV,…
Weeds sampling for map reconstruction: a Markov random field approach
2012
In the past 15 years, there has been a growing interest for the study of the spatial repartition of weeds in crops, mainly because this is a prerequisite to herbicides use reduction. There has been a large variety of statistical methods developped for this problem ([5], [7], [10]). However, one common point of all of these methods is that they are based on in situ collection of data about weeds spatial repartition. A crucial problem is then to choose where, in the eld, data should be collected. Since exhaustive sampling of a eld is too costly, a lot of attention has been paid to the development of spatial sampling methods ([12], [4], [6] [9]). Classical spatial stochastic model of weeds cou…
Échantillonnage adaptatif optimal dans les champs de Markov, application à l’échantillonnage d’une espèce adventice
2012
This work is divided into two parts: (i) the theoretical study of the problem of adaptive sampling in Markov Random Fields (MRF) and (ii) the modeling of the problem of weed sampling in a crop field and the design of adaptive sampling strategies for this problem. For the first point, we first modeled the problem of finding an optimal sampling strategy as a finite horizon Markov Decision Process (MDP). Then, we proposed a generic algorithm for computing an approximate solution to any finite horizon MDP with known model. This algorithm, called Least-Squared Dynamic Programming (LSDP), combines the concepts of dynamic programming and reinforcement learning. It was then adapted to compute adapt…
In Situ, Airborne Instrumentation: Addressing and Solving Measurement Problems in Ice Clouds
2012
The workshop on in situ airborne instrumentation: addressing and solving measurement problems in ice clouds, June 25-27, 2010, Oregon, aimed to identify unresolved questions concerning ice formation and evolution in ice clouds, assess the current state of instrumentation that can address these problems, introduce emerging technology that may overcome current measurement issues, and recommend future courses of action to improve our understanding of ice cloud microphysical. Eleven presentations were made covering measurement challenges associated measuring the composition and concentration of all the modes of ice nuclei (IN), measuring the morphology, mass, surface, and optical properties of …
Carbonated Inheritance in the Eastern Tibetan Lithospheric Mantle: Petrological Evidences and Geodynamic Implications
2020
International audience; The timing and mechanism of formation of the Tibet Plateau remain elusive, and even the present-day structure of the Tibetan lithosphere is hardly resolved, due to conflicting interpretations of the geophysical data. We show here that significant advances in our understanding of this orogeny could be achieved through a better assessment of the composition and rheological properties of the deepest parts of the Tibetan lithosphere, leading in particular to a reinterpretation of the global tomographic cross sections. We report mantle phlogopite xenocrysts and carbonate-bearing ultramafic cumulates preserved in Eocene potassic rocks from the Eastern Qiangtang terrane, wh…
Evaluation ex ante des conséquences de l'adoption de la production intégrée en grandes cultures à l'échelle de la Bourgogne
2015
The agriculture in France is under intense pressure. Farmers are asked to change their crop management, to evolve toward agroecology, to follow the principles of Integrated Pest Management (IPM) and to reduce pesticide use. However such an evolution toward an alternative agricultural model will be possible only if innovative cropping systems are able to maintain competitive and profitable farms.The aim of our work is to contribute to the debates about this issue, by evaluating ex ante the potential consequences of adopting the principles of IPM over one whole agricultural region, taking into account the diversity of production situations within this region. We considered the Burgundy region…
Focal Points in Collective Free Improvisation
2013
OLLECTIVE FREE IMPROVISATION (herein abbreviated as CFI), while not a recent phenomenon in music (free jazz’s first experiments date from the late 1950s), remains under-studied. The extant literature either deals with political aspects (Carles and Comolli 2000) or tries to analyze the resulting music, using musicological tools (Jost 1994) or new concepts drawn from the complexity sciences (Borgo 2005). My research on CFI focuses on a cognitive approach, in order to understand the process of collective improvisation: 1 how a group of improvisers who do not know each other and are not using a common referent 2 (Pressing 1988) can answer the challenge of making music together. This paper deals…
Electronic noses : specify or disappear
2000
Abstract When the quality control is achieved by using GC or GC/MS, the apparatus must comply with the applicable norms, but what about “electronic noses”? End users demand for formal specifications for selectivity, sensitivity, repeatability and sample throughput. The behavioural modelling of electronic olfactometers may provide specifications for these required parameters. This will allow both the measure itself, and evaluate the influence of the experimental errors on the sample classification. Users may expect to find a methodology allowing the performances of systems to be checked before any final decision and during routine use. We have demonstrated that the system sensitivity and log…