Science & Mathematics

This manuscript presents a novel Bayesian active learning reliability method integrating both Bayesian failure probability estimation and Bayesian decision-theoretic multi-point enrichment process. First, an epistemic uncertainty measure called integrated margin probability (IMP) is proposed as an upper bound for the mean absolute deviation of failure probability estimated by Kriging. Then, adhering to the Bayesian decision theory, a look-ahead learning function called multi-point stepwise margin reduction (MSMR) is defined to quantify the possible reduction of IMP brought by adding a batch of new samples in expectation. The cost-effective implementation of MSMR-based multi-point enrichment process is conducted by three key workarounds: (a) Thanks to analytical tractability of the inner integral, the MSMR reduces to a single integral. (b) The remaining single integral in the MSMR is numerically computed with the rational truncation of the quadrature set. (c) A heuristic treatment of maximizing the MSMR is devised to fastly select a batch of best next points per iteration, where the prescribed or adaptive scheme is used to specify the batch size. The proposed method is tested on two benchmark examples and two dynamic reliability problems. The results indicate that the adaptive scheme in the MSMR gains a good balance between the computing resource consumption and the overall computational time. Then, the MSMR fairly outperforms those existing leaning functions and parallelization strategies in terms of the accuracy of failure probability estimate, the number of iterations, as well as the number of performance function evaluations, especially in complex dynamic reliability problems.

The study was carried out to determine the current levels of nitrate in vegetable and vegetable-based baby foods (a total of 1150 samples) marketed in the Region of Valencia (Spain) over the period 2000-2008 and to estimate the toxicological risk associated with their intake. Average (median) levels of nitrate in lettuce, iceberg-type lettuce and spinach (1156, 798 and 1410 mg kg-1 w.w. respectively) were lower than the maximum limits established by the EU legislation. Thirteen fresh spinach samples exceeded the regulatory limits. Median nitrate values in other vegetables for which a maximum limit has not been fixed by the European Commission were 196, 203, 1597, 96, 4474 and 2572 mg kg-1 w.w. (for potato, carrot, chard, artichoke, rucola and lab's lettuce respectively). The estimated nitrate daily intake through vegetable consumption for adult, extreme consumers and children were found to be about 29%, 79.8% and 15.1% respectively, of the acceptable daily intake (3.7 mg kg-1). The levels (median value 60.4 mg kg-1 w.w.) found in vegetable-based baby foods were, in all cases, lower the maximum level proposed by EU legislation. The estimated nitrate daily intake through baby foods for infants between 0-1 and 1-2 years were 13% and 18% respectively, of the acceptable daily intake.

The problem of gain estimation of a superdirective dipole-based array is discussed. The current method to compute the gain, for a given element radiation efficiency, is based on the Array Factor (AF) Theory. In this work it is intended to show that an equivalent formulation can be done using the Spherical Wave Expansion (SWE) theory. Besides the interest in validating this theory, the main objective is a better understanding of the radiation and attenuation phenomena that occurs in superdirective arrays. Moreover, the numerical sensitivity affecting the problem diverges as the inter-elements distance tends to zero. Having a larger set of functions describing the radiated field, such as in the case of the SWE theory, allows the possibility to decrease the sensitivity. Consequentially the sensitivity limits imposed by the classical formulation in AF theory can be overcame

Explorer la théorie des ancres et les espaces cognitifs dans la cartographie multi-échelle. Maïeul GRUGET & Guillaume TOUYA LASTIG, Univ Gustave Eiffel, ENSG, IGN Votre carte mentale pourrait modifier la manière dont vous percevez une cartographie multi-échelle. Vers un zoom cognititif ancré ?

Publiée in L'agora de Palmyre Delplace - Feydy 2005 BAH 175 ; Haut empire romain 70-75 à 130 ap. - Mission archéologique française à Palmyre. 1939; Gélatine (9x15)

Benjamin Britten, compositeur « typiquement anglais » ? C’est ce que les commentateurs de son œuvre ont fréquemment retenu comme axe analytique de son langage musical. L’étude de ses cycles de mélodies en langue française – Quatre Chansons françaises (1928), les Illuminations (1939) et les French Folk Song Arrangements (1942) – permet pourtant de proposer d’autres lectures. L’éventail des emprunts (pastiche, citation, arrangement, etc.) à un langage littéraire et musical français servent des objectifs divers au cours de la carrière du compositeur. L’utilisation d’un langage exogène, d’abord méthode d’apprentissage de la composition par la copie pendant la formation, devient le lieu du renouvellement de l’inspiration musicale à la maturité. Le détournement d’une langue « nationale » est enfin érigé en un procédé commercial qui tient une place singulière dans l’architecture des concerts donnés par le compositeur.

PURPOSE. To prospectively assess the frequency of abnormal sonographic findings in patients with posttraumatic shoulder pain and/or disability in whom ultrasound (US) was not considered and to assess the effect of sonographic findings on working diagnosis and therapeutic strategy, in order to analyse the possible role of US in the diagnostic work-up of these patients. METHODS. A survey was performed under general practitioners and orthopaedic surgeons. They were requested to refer patients with persistent posttraumatic complaints for an US examination of the shoulder and to fill in a questionnaire concerning working diagnosis and therapy. In fifty patients examinations were performed by two radiologists separately. Findings were confirmed with additional radiographs and/or MRI and/or surgery. Shortly after US a survey was repeated. RESULTS. Sonography showed relevant pathology in 45 (90%) of 50 patients, a proximal humerus fracture in 25 (50%) patients, and a rotator cuff tear in 43 (86%) patients. Twenty-three (92%) fractures were accompanied by a rotator cuff tear, and 23 (54%) rotator cuff tears were accompanied by a fracture. Ten fractures were initially missed radiographically. Sonographic findings changed the working diagnosis and therapeutic strategy in 37 (74%) and 26 (52%) patients, respectively. CONCLUSION. In patients with posttraumatic shoulder complaints US showed a high rate (90%) of relevant pathology. This changed the initial working diagnosis in 74% of the patients and the therapeutic strategy in more than half of the patients. Active referral for sonographic examination may identify these abnormalities in an earlier phase and improve clinical outcome.

Machine learning is the study of designing algorithms that learn from trainingdata to achieve a specific task. The resulting model is then used to predict overnew (unseen) data points without any outside help. This data can be of manyforms such as images (matrix of pixels), signals (sounds,...), transactions (age,amount, merchant,...), logs (time, alerts, ...). Datasets may be defined to addressa specific task such as object recognition, voice identification, anomaly detection,etc. In these tasks, the knowledge of the expected outputs encourages a supervisedlearning approach where every single observed data is assigned to a label thatdefines what the model predictions should be. For example, in object recognition,an image could be associated with the label "car" which suggests that the learningalgorithm has to learn that a car is contained in this picture, somewhere. This is incontrast with unsupervised learning where the task at hand does not have explicitlabels. For example, one popular topic in unsupervised learning is to discoverunderlying structures contained in visual data (images) such as geometric formsof objects, lines, depth, before learning a specific task. This kind of learning isobviously much harder as there might be potentially an infinite number of conceptsto grasp in the data. In this thesis, we focus on a specific scenario of thesupervised learning setting: 1) the label of interest is under represented (e.g.anomalies) and 2) the dataset increases with time as we receive data from real-lifeevents (e.g. credit card transactions). In fact, these settings are very common inthe industrial domain in which this thesis takes place.

The crisis of confidence between Gülen and the AKP raises several questions regarding Turkey’s relationship with Central Asia and the Caucasus, where a number of Gülenist schools have developed.

Laser ablation aerosol particle-time of flight mass spectrometer (LAAP-ToF-MS) measures the size number of particles, and chemical composition of individual particles in real-time. LAAP-ToF-MS measurements of chemical composition are difficult to quantify, mostly because the instrument sensitivities to various chemical species in the multicomponent atmospheric aerosol particles are unknown. In this study, we investigate a field-based approach for quantitative measurements of ammonium, nitrate, sulfate, OC, and EC, in size-segregated atmospheric aerosols, by LAAP-ToF-MS using concurrent measurements from high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), and multi-angle absorption photometer (MAAP). An optical particle counter (OPC) and a high-resolution nanoparticle sizer (scanning mob ility particle sizer, or SMPS), were used to measure the particle size distributions of the particles in order to correct the number concentrations. The intercomparison reveals that the degree of agreement of the mass concentrations of each compound measured with LAAP-ToF-MS and HR-ToF-AMS/MAAP increases in the following order NH4+

Ce mémoire est consacré à la description d'une technique nouvelle permettant une résolution numérique précise et efficace des équations de Navier--Stokes en présence d'interfaces et de surfaces libres. Une première partie est consacrée à la présentation des principes généraux de la méthode appliquée au cas d'écoulements diphasiques. Une attention particulière est accordée au traitement des termes liés à la tension de surface. La méthode est ensuite formalisée dans le cas d'écoulements avec surfaces libres. Plusieurs tests de validation sont présentés incluant : ondes capillaires planes, modes d'oscillation de gouttes, instabilité de Rayleigh--Taylor, montée de bulles dans un liquide. Deux applications principales sont considérées dans les chapitres suivants : sonoluminescence et cavitation. Nous nous intéressons plus particulièrement au couplage entre oscillations radiales et translationelles dans les bulles en lévitation acoustique ainsi qu'à la stabilité des modes de déformation non--sphériques des bulles sonoluminescentes. La formation de jets dans les bulles de cavitation près de parois solides est simulée numériquement et comparée aux séquences photographiques expérimentales. Une étude paramétrique détaillée des effets de la viscosité sur la formation et la vitesse d'impact du jet est effectuée.

In this paper, we propose a new design of a piezoelectric transformer (PT) for low-profile DC/DC converter applications , which increases the output power by using heat transfer equipment. We examined several parameters, which allow us to produce a piezoelectric transformer with optimal efficiency. Instead of looking at the typically optimal loading condition of the PT, we consider the influence of the temperature rise on losses. When the vibration velocity is too large, the piezoelectric transformer generates heat unstably until it cracks. By maintaining the vibration mode and limiting the heat produced by the PT, this design can enhance the power capacities of the PT and thus increase the output power of the DC/DC converter. A finite element analysis (FEA) approach with COMSOL Multiphysics was made to predict PT's working temperature. A theoretical-phenomenological model was also developed to explain the relationship between the equivalent losses resistances and the input voltage at different temperatures. It will be shown that the vibration velocity as well as the heat generation increases the losses. A large vibration velocity and generated heat may cause the temperature feedback loop to enter into an unstable state. We began by modeling a piezoelectric transformer in a DC/DC converter configuration in order to determine the design constraints and variables such as the maximum mechanical current, the temperature distribution, the PT geometrical configuration and the energy balance. In our design, the PT power capacity increases 3 times (i.e. from 4.54 W to 13.29 W) at specific temperature and the effects of the different cooling methods of the system were verified. The study comprises of a theoretical part and experimental proof-of-concept demonstration of the proposed design method.