Isabelle Alfandary, Le Risque de la lettre. Lectures de la poésie moderniste américaine

Dans Le Risque de la lettre, Isabelle Alfandary s’attache à montrer la spécificité de quelques œuvres modernistes américaines, celles, très diverses, et présentées dans leur diversité, d’E. E. Cummings, Gertrude Stein, et John Cage. À partir de ces écritures, considérées trop souvent comme marginales, elle s’est risquée à une théorie de la littérature. Mettant à contribution, de manière féconde, la pensée de Derrida, Lacan et Deleuze entre autres, son essai élabore une « poétique de la lettre..

Transit Analysis Package (TAP and autoKep): IDL Graphical User Interfaces for Extrasolar Planet Transit Photometry

We present an IDL graphical user interface-driven software package designed for the analysis of extrasolar planet transit light curves. The Transit Analysis Package (TAP) software uses Markov Chain Monte Carlo (MCMC) techniques to fit light curves using the analytic model of Mandel and Agol (2002). The package incorporates a wavelet based likelihood function developed by Carter and Winn (2009) which allows the MCMC to assess parameter uncertainties more robustly than classic chi-squared methods by parameterizing uncorrelated "white" and correlated "red" noise. The software is able to simultaneously analyze multiple transits observed in different conditions (instrument, filter, weather, etc). The graphical interface allows for the simple execution and interpretation of Bayesian MCMC analysis tailored to a user's specific data set and has been thoroughly tested on ground-based and Kepler photometry. AutoKep provides a similar GUI for the preparation of Kepler MAST archive data for analysis by TAP or any other analysis software. This paper describes the software release and provides instructions for its use.Comment: 8 pages, 2 figure

Heat Transfer and Flow Analysis of a Novel Low Flow Piezoelectric Air Pump

With the propagation of ever faster and more powerful electronics, the need for active, low power cooling is becoming increasingly apparent. In particular, applications which have traditionally relied only on natural convection will soon require an active cooling solution due to continually rising heat loads. A promising solution lies in utilizing piezoelectric materials via fans or pumps. Examples of such devices include synthetic jets and piezoelectric pumps, both of which rely on an oscillating diaphragm to induce flow. The device investigated in this thesis is able to generate flow rates up to 1 L/min and overcome pressures of over 2 kPa. The focus is to experimentally characterize the cooling potential of a piezoelectric-based air pump oriented normal to a heated surface, an environment similar to jet impingement. Experimental characterizations were made through the use of a thin film heater which provided a constant heat flux while an infrared camera was used to capture the resulting temperature field of the heated surface. Full-field data of the convection coefficient was analyzed as a function of vibration amplitude of the piezoelectric diaphragm and distance from the nozzle to the heated target. The maximum heat transfer coefficient was found to always be at the stagnation point regardless of vibration amplitude or distance to the target. Correlations have been developed which account for both variables considered and can be used to predict the performance of future designs which rely on the same physical characteristics. Further, because of the piezoelectric blower’s ability to overcome large pressure drops, a theoretical analysis was conducted to assess the viability of using them in oscillating flow cooling. It was found to be a reasonable driver of reciprocating flow that can keep fluid temperature change low. Additionally it was found that reciprocating flow allows for a more uniform temperature distribution over a heated surface

Characterizing Thrust Performance for Free and Confined Oscillating Cantilevers

Although not identical to the motion employed by nature’s swimmers and flyers, the simple harmonic oscillations of cantilever-like structures have been shown to provide efficient low power solutions for applications ranging from thermal management to propulsion. However, in order to quantify their true potential, the resulting flow field and corresponding thrust must be better understood. In this experimental work, thin, flexible cantilevers vibrating in their fundamental mode are analyzed in terms of the flow field produced and the thrust generated. The actuation is achieved via a piezoelectric patch mounted near its base. An oscillating voltage tuned to the first resonance of the structure causes vibrations at the free end of the cantilever. The flow field is experimentally measured using Particle Image Velocimetry (PIV). Two dimensional flow fields are extracted from multiple x-y and y-z planes, and revealed that inward flow occurs upstream as well as above and below the flat face of the cantilever. It was also found that there is a net inward volumetric flow at the corners of the cantilever. Observing the flow off the tip of the fan lead to the finding that the dominant flow velocity occurs not at the center of the fan, but at the midpoints between the center and each edge. The flow field data are primarily used to motivate future geometry, and boundary configurations that could greatly enhance the thrust capabilities of the cantilever by directing the flow downstream in a more effective manner. The thrust produced was experimentally measured using a high resolution scale. Clear trends were observed and correlations developed to help predict the thrust as a function of the operating parameters including the cantilever geometry and vibration amplitude and frequency. Attempts at shaping the flow were investigated by introducing sidewalls on both sides of the oscillating cantilever. The sidewall boundary condition was tested with thrust performance and power consumption in mind, and it was found that the position of the tip on the cantilever in relation to the edge of the sidewall has an effect on power consumption that is dramatic and incongruent with what one would expect. This research provides the critical experimental analysis to gauge the viability of using simple and energy efficient actuation from cantilever-like structures in place of more complicated solutions which attempt to maintain a higher degree of biomimicry

KELT-4Ab: An inflated Hot Jupiter transiting the bright (V~10) component of a hierarchical triple

We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of a hierarchical triple stellar system. The host star is an F star with T_(eff) = 6206 ± 75 K, log g = 4.108 ± 0.014, [Fe/H] = -0.116_(-0.069)^(+0.065, M_* = 1.201_(-0.061)^(+0.067) M_☉, and R_* = 1.603_(-0.038)^(+0.039) R_☉. The best-fit linear ephemeris is BJD_(TDB); = 2456193.29157 ± 0.00021 + E(2.9895936 ± 0.0000048). With a magnitude of V ~ 10, a planetary radius of 1.699_(-0.045)^(+0.046); R_J, and a mass of 0.902_(-0.059)^(+0.060) M_J, it is the brightest host among the population of inflated Hot Jupiters (R_P > 1.5 R_J), making it a valuable discovery for probing the nature of inflated planets. In addition, its existence within a hierarchical triple and its proximity to Earth (210 pc) provide a unique opportunity for dynamical studies with continued monitoring with high resolution imaging and precision radial velocities. The projected separation between KELT-4A and KELT-4BC is 328 ± 16 AU and the projected separation between KELT-4B and KELT-4C is 10.30 ± 0.74 AU. Assuming face-on, circular orbits, their respective periods would be 3780 ± 290 and 29.4 ± 3.6 years and the astrometric motions relative to the epoch in this work of both the binary stars around each other and of the binary around the primary star would be detectable now and may provide meaningful constraints on the dynamics of the system