14,836 research outputs found

    Naturwall: active timber wall for renovation of existent buildings

    Get PDF
    The renovation of old buildings is actually the challenge to cope with increased effort in order to reduce climate global change, channeling more investment and awareness in this sense, defining more experimentations and find innovative solutions. The difficulty of carrying out an intervention on the existing buildings necessarily arise from the lack of information on the existing structure and the lack of coordinated processes between the multidisciplinary skills involved, as well as a difficulty to optimize the process that would make it even more competitive on the renovation work instead on the new construction. Naturwall is an innovative energy saving system for existent buildings by using wood in multifunctional components able to mitigate the environmental effort in building management. The project meant to introduce an industrialized design method in the renovation of existing build environment that highlights opportunities gave by "off site" production and parametric design approach, without neglecting the aesthetical values and the possibility to change the architectural image of residential and non residential constructions. The project aims to create a representative model of solution that will be promoted in Italy and widespread in other similar contex

    A direct kinematical derivation of the relativistic Sagnac effect for light or matter beams

    Full text link
    The Sagnac time delay and the corresponding Sagnac phase shift, for relativistic matter and electromagnetic beams counter-propagating in a rotating interferometer, are deduced on the ground of relativistic kinematics. This purely kinematical approach allows to explain the ''universality'' of the effect, namely the fact that the Sagnac time difference does not depend on the physical nature of the interfering beams. The only prime requirement is that the counter-propagating beams have the same velocity with respect to any Einstein synchronized local co-moving inertial frame.Comment: 10 pages, 1 EPS figure, to appear in General Relativity and Gravitatio

    Clues on the evolution of the Carina dwarf spheroidal galaxy from the color distribution of its red giant stars

    Get PDF
    The thin red giant branch (RGB) of the Carina dwarf spheroidal galaxy appears at first sight quite puzzling and seemingly in contrast with the presence of several distinct bursts of star formation. In this Letter, we provide a measurement of the color spread of red giant stars in Carina based on new BVI wide-field observations, and model the width of the RGB by means of synthetic color-magnitude diagrams. The measured color spread, Sigma{V-I}=0.021 +/- 0.005, is quite naturally accounted for by the star-formation history of the galaxy. The thin RGB appears to be essentially related to the limited age range of its dominant stellar populations, with no need for a metallicity dispersion at a given age. This result is relatively robust with respect to changes in the assumed age-metallicity relation, as long as the mean metallicity over the galaxy lifetime matches the observed value ([Fe/H] = -1.91 +/- 0.12 after correction for the age effects). This analysis of photometric data also sets some constraints on the chemical evolution of Carina by indicating that the chemical abundance of the interstellar medium in Carina remained low throughout each episode of star formation even though these episodes occurred over many Gyr.Comment: 4 pages, 3 figures, accepted for publication in the Astrophysical Journal Letter

    Auralization of a Supersonic Business Jet Using Advanced Takeoff Procedures

    Get PDF
    Recent NASA studies of a supersonic business jet airplane indicated that advanced takeoff procedures could be used to reduce noise at the lateral sideline location to a level at which Chapter 4 noise certification requirements could be met. The studies were conducted with the NASA Aircraft Noise Prediction Program, using an analytical model of the airframe and its engines. The advanced procedure consists of a higher-speed climbout and a programmed thrust lapse in which the engine thrust is automatically and gradually reduced immediately after the runway obstacle is cleared. In this paper, the authors utilize the results of the most recent study as the basis of an auralization of the predicted noise. Modifications to the NASA Auralization Framework necessary for that process are described. The auralizations are used to demonstrate differences between standard and advanced takeoff pro ond those that may be observed through comparison of integrated noise metrics

    The Sagnac Effect in curved space-times from an analogy with the Aharonov-Bohm Effect

    Full text link
    In the context of the natural splitting, the standard relative dynamics can be expressed in terms of gravito-electromagnetic fields, which allow to formally introduce a gravito-magnetic Aharonov-Bohm effect. We showed elsewhere that this formal analogy can be used to derive the Sagnac effect in flat space-time as a gravito-magnetic Aharonov-Bohm effect. Here, we generalize those results to study the General Relativistic corrections to the Sagnac effect in some stationary and axially symmetric geometries, such as the space-time around a weakly gravitating and rotating source, Kerr space-time, G\"{odel} universe and Schwarzschild space-time.Comment: 14 pages, 1 EPS figure, LaTeX, accepted for publication in General Relativity and Gravitatio

    Quantum Interference Effects in Slowly Rotating NUT Space-time

    Full text link
    General relativistic quantum interference effects in the slowly rotating NUT space-time as the Sagnac effect and the phase shift effect of interfering particle in neutron interferometer are considered. It was found that in the case of the Sagnac effect the influence of NUT parameter is becoming important due to the fact that the angular velocity of the locally non rotating observer must be larger than one in the Kerr space-time. In the case of neutron interferometry it is found that due to the presence of NUT-parameter an additional term in the phase shift of interfering particle emerges. This term can be, in principle, detected by sensitive interferometer and derived results can be further used in experiments to detect the gravitomagnetic charge. Finally, as an example, we apply the obtained results to the calculation of the UCN (ultra-cold neutrons) energy level modification in the slowly rotating NUT space-time.Comment: 11 pages, 1 figure, accepted for publication in Int. J. Mod. Phys. D; added reference
    corecore