Fluid-Structure Interaction

apport de recherch

Investigation of remote sensing techniques of measuring soil moisture

Major activities described include development and evaluation of theoretical models that describe both active and passive microwave sensing of soil moisture, the evaluation of these models for their applicability, the execution of a controlled field experiment during which passive microwave measurements were acquired to validate these models, and evaluation of previously acquired aircraft microwave measurements. The development of a root zone soil water and soil temperature profile model and the calibration and evaluation of gamma ray attenuation probes for measuring soil moisture profiles are considered. The analysis of spatial variability of soil information as related to remote sensing is discussed as well as the implementation of an instrumented field site for acquisition of soil moisture and meteorologic information for use in validating the soil water profile and soil temperature profile models

An overview on green house gas emission characteristics and energy evaluation of ocean energy systems from life cycle assessment and energy accounting studies

An analysis has been made as regards emission characteristics of ocean energy systems from life cycle assessment and scope of energy availability from energy accounting studies. Assessment tools developed and standardized were the indices like scope of Green house gases (GHG) emission per kWh power generation, percentage of CO2 saved compared to coal fired power station and the energy payback period. Emission characteristics of ocean energy systems were also compared with that from solar power, bio-fuels and wind energy systems. Four case studies were made comprising of wave energy converters, Ocean Thermal Energy Conversion (OTEC) system and tidal energy. It could be observed that CO2 emission percentage saved from ocean energy schemes were more than 95 per cent; and energy payback period varied between one year and a little higher than two years, depending on the type of the device

On the existence of effective potentials in time-dependent density functional theory

We investigate the existence and properties of effective potentials in time-dependent density functional theory. We outline conditions for a general solution of the corresponding Sturm-Liouville boundary value problems. We define the set of potentials and v-representable densities, give a proof of existence of the effective potentials under certain restrictions, and show the set of v-representable densities to be independent of the interaction.Comment: 13 page

Some stationary properties of a QQ-ball in arbitrary space dimensions

Introducing new physically motivated ans\"{a}tze, we explore both analytically and numerically the classical and absolute stabilities of a single $Q$-ball in an arbitrary number of spatial dimensions $D$, working in both the thin and thick wall limits.Comment: 35 pages, 32 figures; added references, corrected typo

Radar cross calibration investigation TAMU radar polarimeter calibration measurements

A short pulse, 20 MHz bandwidth, three frequency radar polarimeter system (RPS) operates at center frequencies of 10.003 GHz, 4.75 GHz, and 1.6 GHz and utilizes dual polarized transmit and receive antennas for each frequency. The basic lay-out of the RPS is different from other truck mounted systems in that it uses a pulse compression IF section common to all three RF heads. Separate transmit and receive antennas are used to improve the cross-polarization isolation at each particular frequency. The receive is a digitally controlled gain modulated subsystem and is interfaced directly with a microprocesser computer for control and data manipulation. Antenna focusing distance, focusing each antenna pair, rf head stability, and polarization characteristics of RPS antennas are discussed. Platform and data acquisition procedures are described

Analytic Examples, Measurement Models and Classical Limit of Quantum Backflow

We investigate the backflow effect in elementary quantum mechanics - the phenomenon in which a state consisting entirely of positive momenta may have negative current and the probability flows in the opposite direction to the momentum. We compute the current and flux for states consisting of superpositions of gaussian wave packets. These are experimentally realizable but the amount of backflow is small. Inspired by the numerical results of Penz et al (M.Penz, G.Gr\"ubl, S.Kreidl and P.Wagner, J.Phys. A39, 423 (2006)), we find two non-trivial wave functions whose current at any time may be computed analytically and which have periods of significant backflow, in one case with a backwards flux equal to about 70 percent of the maximum possible backflow, a dimensionless number $c_{bm} \approx 0.04$, discovered by Bracken and Melloy (A.J.Bracken and G.F.Melloy, J.Phys. A27, 2197 (1994)). This number has the unusual property of being independent of $\hbar$ (and also of all other parameters of the model), despite corresponding to an obviously quantum-mechanical effect, and we shed some light on this surprising property by considering the classical limit of backflow. We discuss some specific measurement models in which backflow may be identified in certain measurable probabilities.Comment: 33 pages, 14 figures. Minor revisions. Published versio

The Controversy Surrounding The Man Who Would Be Queen: A Case History of the Politics of Science, Identity, and Sex in the Internet Age

In 2003, psychology professor and sex researcher J. Michael Bailey published a book entitled The Man Who Would Be Queen: The Science of Gender-Bending and Transsexualism. The book’s portrayal of male-to-female (MTF) transsexualism, based on a theory developed by sexologist Ray Blanchard, outraged some transgender activists. They believed the book to be typical of much of the biomedical literature on transsexuality—oppressive in both tone and claims, insulting to their senses of self, and damaging to their public identities. Some saw the book as especially dangerous because it claimed to be based on rigorous science, was published by an imprint of the National Academy of Sciences, and argued that MTF sex changes are motivated primarily by erotic interests and not by the problem of having the gender identity common to one sex in the body of the other. Dissatisfied with the option of merely criticizing the book, a small number of transwomen (particularly Lynn Conway, Andrea James, and Deirdre McCloskey) worked to try to ruin Bailey. Using published and unpublished sources as well as original interviews, this essay traces the history of the backlash against Bailey and his book. It also provides a thorough exegesis of the book’s treatment of transsexuality and includes a comprehensive investigation of the merit of the charges made against Bailey that he had behaved unethically, immorally, and illegally in the production of his book. The essay closes with an epilogue that explores what has happened since 2003 to the central ideas and major players in the controversy

Gravitational Lensing Effect on the Two-point Correlation of Hotspots in the Cosmic Microwave Background

We investigate the weak gravitational lensing effect due to the large-scale structure of the universe on two-point correlations of local maxima ({\em hotspots}) in the 2D sky map of the cosmic microwave background (CMB) anisotropy. According to the Gaussian random statistics as most inflationary scenarios predict, the hotspots are discretely distributed with some {\em characteristic} angular separations on the last scattering surface owing to oscillations of the CMB angular power spectrum. The weak lensing then causes pairs of hotspots which are separated with the characteristic scale to be observed with various separations. We found that the lensing fairly smoothes the oscillatory features of the two-point correlation function of hotspots. This indicates that the hotspots correlations can be a new statistical tool for measuring shape and normalization of the power spectrum of matter fluctuations from the lensing signatures.Comment: 6 pages, 2 figures; replaced with published versio