581 research outputs found

    Tectonic Regime as a Control Factor for Crustal Fault Zone (CFZ) Geothermal Reservoir in an Amagmatic System: A 3D Dynamic Numerical Modeling Approach

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    Crustal fault zones provide interesting geological targets for high-temperature geothermal energy source in naturally deep-fractured basement areas. Field and laboratory studies have shown the ability of these systems to let fluid flow down to the brittle–ductile transition. However, several key questions about exploration still exist, in particular the fundamental effect of tectonic regimes on fluid flow in fractured basement domains. Based on poro-elasticity assumption, we considered an idealized 3D geometry and realistic physical properties. We examined a model with no tectonic regime (benchmark experiment) and a model with different tectonic regimes, namely a compressional, an extensional and a strike-slip tectonic regime. Compared to the benchmark experiment, the results demonstrate that different tectonic regimes cause pressure changes in the fault/basement system. The tectonic-induced pressure changes affect convective patterns, onset of convection as well as the spatial extent of thermal plumes and the intensity of temperature anomalies. Driven by poro-elastic forces, temperature anomalies around vertical faults in a strike-slip tectonic regime have a spatial extent that should be considered in preliminary exploratory phases

    A statistical model for the steady-state behavior of the multi-split LMS algorithm

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    - Ce travail presente un modèle de comportement en régime permanant de l'algorithme «multi-split LMS». Des expressions de récurrences sont obtenues pour le vecteur de coefficients moyens et pour l'erreur carré moyenne. Des résultats de simulation démontrent une conformité excellent avec les prédictions théoriques et nous permettent de valider le modèle proposé

    Optimization of cw sodium laser guide star efficiency

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    Context: Sodium laser guide stars (LGS) are about to enter a new range of laser powers. Previous theoretical and numerical methods are inadequate for accurate computations of the return flux and hence for the design of the next-generation LGS systems. Aims: We numerically optimize the cw (continuous wave) laser format, in particular the light polarization and spectrum. Methods: Using Bloch equations, we simulate the mesospheric sodium atoms, including Doppler broadening, saturation, collisional relaxation, Larmor precession, and recoil, taking into account all 24 sodium hyperfine states and on the order of 100 velocity groups. Results: LGS return flux is limited by "three evils": Larmor precession due to the geomagnetic field, atomic recoil due to radiation pressure, and transition saturation. We study their impacts and show that the return flux can be boosted by repumping (simultaneous excitation of the sodium D2a and D2b lines with 10-20% of the laser power in the latter). Conclusions: We strongly recommend the use of circularly polarized lasers and repumping. As a rule of thumb, the bandwidth of laser radiation in MHz (at each line) should approximately equal the launched laser power in Watts divided by six, assuming a diffraction-limited spot size.Comment: 15 pages, 12 figures, to be published in Astronomy & Astrophysics, AA/2009/1310

    Automated tracking and analysis of centrosomes in early Caenorhabditis elegans embryos

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    Motivation: The centrosome is a dynamic structure in animal cells that serves as a microtubule organizing center during mitosis and also regulates cell-cycle progression and sets polarity cues. Automated and reliable tracking of centrosomes is essential for genetic screens that study the process of centrosome assembly and maturation in the nematode Caenorhabditis elegans

    AMANDA : an autonomous self-powered miniaturized smart sensing embedded system

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    ​© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper introduces an Autonomous Smart Sensing Card (ASSC), an embedded system that will be powered indoors and outdoors by harvested energy, have miniaturized dimensions and serve multi-sensorial IoT applications for smart living and working environments. It will consist of a combination of newly developed and optimized off-the-shelf or close-tocommercialization technologies such as PV harvesters, energy storage and power management units, MCUs and sensors, all packed with a form factor under 3mm in thickness. The system will introduce technical breakthroughs that will boost further miniaturization, a small footprint, ultra-low power consumption as well as short- and long-range communications

    Statistical characteristics of formation and evolution of structure in the universe

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    An approximate statistical description of the formation and evolution of structure of the universe based on the Zel'dovich theory of gravitational instability is proposed. It is found that the evolution of DM structure shows features of self-similarity and the main structure characteristics can be expressed through the parameters of initial power spectrum and cosmological model. For the CDM-like power spectrum and suitable parameters of the cosmological model the effective matter compression reaches the observed scales RwallR_{wall}\sim 20 -- 25h1h^{-1}Mpc with the typical mean separation of wall-like elements DSLSSD_{SLSS}\sim 50 -- 70h1h^{-1}Mpc. This description can be directly applied to the deep pencil beam galactic surveys and absorption spectra of quasars. For larger 3D catalogs and simulations it can be applied to results obtained with the core-sampling analysis. It is shown that the interaction of large and small scale perturbations modulates the creation rate of early Zel'dovich pancakes and generates bias on the SLSS scale. For suitable parameters of the cosmological model and reheating process this bias can essentially improve the characteristics of simulated structure of the universe. The models with 0.3Ωm0.50.3\leq \Omega_m \leq 0.5 give the best description of the observed structure parameters. The influence of low mass "warm" dark matter particles, such as a massive neutrino, will extend the acceptable range of Ωm\Omega_m and hh.Comment: 20pages, 7 figures, MNRAS in pres
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