Konserwacja zachowawcza a trwałość budowli drewnianych

The paper outlines the main problems associated with the durability of wooden buildings in the context of biodegradation. Wood destroying organisms were listed and their climatic requirements were pointed. It was indicated that the main factor affecting the durability of the old historical buildings, was the selection of wood. Traditional carpentry solutions ensuring the durability of timber structures were presented.W pracy zaprezentowano główne problemy związane z trwałością budowli drewnianych w kontekście biokorozji. Wymieniono czynniki biokorozji występujące w architekturze drewnianej oraz ich zależność od warunków klimatycznych. Wskazano główne czynniki wpływające na wielowiekową trwałość budowli historycznych, w tym dobór materiałów. Dokonano przeglądu rozwiązań konstrukcyjnych przyczyniających się do zwiększenia trwałości obiektów, zarówno tych wyrosłych z tradycji ciesielskiej, jak i współcześnie stosowanych zabiegów konserwatorskich

Sensitivity of synthetic aperture laser optical feedback imaging

In this paper we compare the sensitivity of two imaging configurations both based on Laser Optical Feedback Imaging (LOFI). The first one is direct imaging, which uses conventional optical focalisation on target and the second one is made by Synthetic Aperture (SA) Laser, which uses numerical focalisation. We show that SA configuration allows to obtain good resolutions with high working distance and that the drawback of SA imagery is that it has a worse photometric balance in comparison to conventional microscope. This drawback is partially compensated by the important sensitivity of LOFI. Another interest of SA relies on the capacity of getting a 3D information in a single x-y scan

Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors

In this paper we present an experimental setup based on Laser Optical Feedback Imaging (LOFI) and on Synthetic Aperture (SA) with translational scanning by galvanometric mirrors for the purpose of making deep and resolved images through scattering media. We provide real 2D optical synthetic-aperture image of a fixed scattering target with a moving aperture and an isotropic resolution. We demonstrate theoretically and experimentally that we can keep microscope resolution beyond the working distance. A photometric balance is made and we show that the number of photons participating in the final image decreases with the square of the reconstruction distance. This degradation is partially compensated by the high sensitivity of LOFI

Experimental comparison of autodyne and heterodyne laser interferometry using a Nd:YVO4 microchip laser

Using a Nd:YVO4 microchip laser with a relaxation frequency in the megahertz range, we have experimentally compared a heterodyne interferometer based on a Michelson configuration with an autodyne interferometer based on the laser optical feedback imaging (LOFI) method regarding their signal to noise ratios. In the heterodyne configuration, the beating between the reference beam and the signal beam is realized outside the laser cavity while in the autodyne configuration, the wave beating takes place inside the laser cavity and the relaxation oscillations of the laser intensity then play an important part. For a given laser output power, object under investigation and detection noise level, we have determined the amplification gain of the LOFI interferometer compared to the heterodyne interferometer. LOFI interferometry is demonstrated to show higher performances than heterodyne interferometry for a wide range of laser power and detection level of noise. The experimental results are in good agreement with the theoretical predictions

Limitations of synthetic aperture laser optical feedback imaging

In this paper we study the origin and the effect of amplitude and phase noise on Laser Optical Feedback Imaging (LOFI) associated with Synthetic Aperture (SA) imaging system. Amplitude noise corresponds to photon noise and acts as an additive noise, it can be reduced by increasing the global measurement time. Phase noise can be divided in three families: random, sinusoidal and drift phase noise; we show that it acts as a multiplicative noise. We explain how we can reduce phase noise by making oversampling or multiple measurements depending on its type. This work can easily be extended to all SA systems (Radar, Laser or Terahertz), especially when raw holograms are acquired point by point

Strategic research and innovation agenda on circular economy

CICERONE aims to bring national, regional and local governments together to jointly tackle the circular economy transition needed to reach net-zero carbon emissions and meet the targets set in the Paris Agreement and EU Green Deal. This document represents one of the key outcomes of the project: a Strategic Research & Innovation Agenda (SRIA) for Europe, to support owners and funders of circular economy programmes in aligning priorities and approaching the circular economy transition in a systemic way

Preventive conservation of historical wooden architecture

W pracy zaprezentowano główne problemy związane z trwałością budowli drewnianych w kontekście biokorozji. Wymieniono czynniki biokorozji występujące w architekturze drewnianej oraz ich zależność od warunków klimatycznych. Wskazano główne czynniki wpływające na wielowiekową trwałość budowli historycznych, w tym dobór materiałów. Dokonano przeglądu rozwiązań konstrukcyjnych przyczyniających się do zwiększenia trwałości obiektów, zarówno tych wyrosłych z tradycji ciesielskiej, jak i współcześnie stosowanych zabiegów konserwatorskich.The paper outlines the main problems associated with the durability of wooden buildings in the context of biodegradation. Wood destroying organisms were listed and their climatic requirements were pointed. It was indicated that the main factor affecting the durability of the old historical buildings, was the selection of wood. Traditional carpentry solutions ensuring the durability of timber structures were presented

Modélisation et étude numérique d'une expérience de croissance cristalline

Universités : Université scientifique et médicale de Grenoble et Institut national polytechnique de GrenobleModélisation de la méthode Czochralski et traitement numérique du modèle adopté. Le modèle mathématique est exprimé sous la forme d'un problème (p) non linéaire de surface libre dans lequel intervient un paramètre auxiliaire f, la vitesse de fabrication. Une méthode itérative est utilisée pour résoudre le problème (p)