Search results for "laser"

Study and 3D survey of the Roman baths in the archaeological site of Lylibaeum (Marsala, Italy)

2020

Abstract Archaeological documentation is a fundamental step for research and conservation planning phases. Nowadays traditional recording is always supported by geomatics technologies which offer important support to the growth of archaeological study. The integration of sensors and methodologies seems to give the best results, in terms of time, costs and accuracy of products. In particular, the combination of Terrestrial Laser Scanner (TLS) and Unmanned Aerial Vehicle (UAV) can help the documentation of complex sites and the production of 3D and 2D products for different purposes. The paper focuses on the integration of TLS and UAV methodologies to record the thermal baths of the Roman Dom…

Il soffitto a muqarnas della Cappella Palatina

2019

Nel saggio vengono indagati i temi del rilievo, della documentazione digitale 3D, dello studio delle geometrie e della divulgazione multimediale del soffitto ligneo a muqarnas della Cappella Palatina nel Palazzo Reale di Palermo.

Luminescence of GeO2 glass, rutile-like and α-quartz-like crystals

2006

Abstract The luminescence of GeO 2 rutile-like crystals was studied. Crystals were grown from a melt of germanium dioxide and sodium bicarbonate mixture. Luminescence of the crystal was compared with that of sodium germanate glasses produced in reduced and oxidized conditions. A luminescence band at 2.3 eV was observed under N 2 laser (337 nm). At higher excitation photon energies and X-ray excitation an additional band at 3 eV appears in luminescence. The band at 2.3 eV possesses intra-center decay time constant about 100 μs at 290 K and about 200 μs at low temperature. Analogous luminescence was obtained in reduced sodium germanate glasses. No luminescence was observed in oxidized glasses…

Atomic spectroscopy: a review

2010

Atomic Absorption Spectrometry 4653 Flame Atomic Absorption Spectrometry 4653 Electrothermal Atomic Absorption Spectrometry 4654 Volatile Species Generation Atomic Absorption Spectrometry 4654 Direct Solids Atomic Absorption Spectrometry 4655 Continuum Source Atomic Absorption Spectrometry 4655 Atomic Fluorescence Spectrometry 4655 Atomic Emission Spectrometry 4656 DC Arc and Low-Power RF Radiation Sources 4656 Inductively Coupled Plasmas 4656 Microwave Induced Plasmas 4658 Microplasmas 4658 Laser Induced Breakdown Spectroscopy 4658 Glow Discharge Optical Emission and Mass Spectrometry 4660 Fundamental Studies 4660 Methodological Studies and Applications of GD-OES and GDMS 4661 New GD Sourc…

Nanosecond laser surface modification of AISI 304L stainless steel: Influence the beam overlap on pitting corrosion resistance

2014

Abstract Surface modifications of AISI 304L stainless steel by laser surface melting (LSM) were investigated using a nanosecond pulsed laser-fibre doped by ytterbium at different overlaps. The objective was to study the change in the corrosion properties induced by the treatment of the outer-surface of the stainless steel without modification of the bulk material. Different analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and glow discharge optical emission spectrometry (GDOES) were used to characterize the laser-melted surface. The corrosion resistance was evaluated in a chloride solution at room temperature by electrochemical tests. The results sh…

Rilievo ed elaborazione di dati laser acquisiti con sistemi MMS in un parco urbano

2013

Questo articolo riassume l'esperienza acquisita tra il 2012 e il 2013 dal Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale e dei Materiali dell'Università degli Studi di Palermo per l'indagine integrata del Parco Ninni Cassarà a Palermo, Italia, e la successiva sperimentazione di metodi, strumenti e tecniche basate su ricerche in corso, per quanto riguarda l'acquisizione e l'elaborazione dei dati GNSS e laser Scanner. Il lavoro è stato affrontato al fine di selezionare le tecniche meno costose e veloci da applicare in fase di acquisizione. Dopo la prima monumentazione di sedici punti di controllo distribuiti all'interno del sito e rilevati con ricevitori GNSS, la è stata pianific…

Supramolecular functionalization and concomitant enhancement in properties of Au25 clusters

2014

We present a versatile approach for tuning the surface functionality of an atomically precise 25 atom gold cluster using specific host-guest interactions between ?-cyclodextrin (CD) and the ligand anchored on the cluster. The supramolecular interaction between the Au25 cluster protected by 4-(t-butyl)benzyl mercaptan, labeled Au25SBB18, and CD yielding Au25SBB18�?�CDn (n = 1, 2, 3, and 4) has been probed experimentally using various spectroscopic techniques and was further analyzed by density functional theory calculations and molecular modeling. The viability of our method in modifying the properties of differently functionalized Au25 clusters is demonstrated. Besides modifying their optoe…

Laser synthesis of ultracold alkali metal dimers: optimization and control

2015

Blood vessel segmentation and width estimation in ultra-wide field scanning laser ophthalmoscopy.

2014

Features of the retinal vasculature, such as vessel widths, are considered biomarkers for systemic disease. The aim of this work is to present a supervised approach to vessel segmentation in ultra-wide field of view scanning laser ophthalmoscope (UWFoV SLO) images and to evaluate its performance in terms of segmentation and vessel width estimation accuracy. The results of the proposed method are compared with ground truth measurements from human observers and with existing state-of-the-art techniques developed for fundus camera images that we optimized for UWFoV SLO images. Our algorithm is based on multi-scale matched filters, a neural network classifier and hysteresis thresholding. After …

Detection of disbonds in multilayer structures by laser-based ultrasonic technique

2008

Adhesively bonded multi-layer structures are frequently used, mostly in the aerospace industry, for their structural efficiency. Nondestructive evaluation of bond integrity in these types of structures, both after manufacturing and for periodic inspection during service, is extremely important. A laser-based ultrasonic technique has been evaluated for non-contact detection of disbonds in aluminum multi-layer structures. Two configurations have been used to detect disbonded areas: pitch-catch with unidirectional guided wave scan and through-transmission with bidirectional scan. Guided wave scanning was done with a laser line source and air-coupled transducer sensing at 500 kHz, 1 ;MHz, and 2…