101,921 research outputs found
Time Resolved Two Dimensional X-Ray Densitometry of a Two Phase Flow Downstream of a Ventilated Cavity
No full textTo measure the void fraction distribution in gas-liquid flows, a two-dimensional x-ray densitometry system was developed. This system is capable of acquiring a two-dimensional projection with a 225 cm2 area of measurement through 21 cm of water. The images can be acquired at rates on the order of 1 kHz. Common sources of error in x-ray imaging, such as x-ray scatter, image distortion, veiling glare, and beam hardening were considered, and mitigated. The measured average void fraction was compared success fully to that of a phantom target and found to be within 1%. To evaluate the performance of the new system, the flow in and downstream of a ventilated nominally two-dimensional partial cavity was investigated and compared to measurements from dual tip fiber optical probes and high speed video. The measurements were found to have satisfactory agreement for void fractions above 5% of the selected void fraction measurement range.Office of Naval Research under grant N00014-10-1-097
Spectroscopy of backscattered Cu ions detected by CR39 through grayness analysis of ion-etch tracks
No full textThe paper reports on a semi-automatic method for the detection and analysis of ion-etch pits generated on Solid State Nuclear Track Detectors (SSNTD) of the CR39 type. The CR39 detectors have been exposed to the elastically scattered Cun+ ions on a 50 nm Au layer deposited on a silicon substrate. After irradiations, foils have been chemically etched for 2 h in a 6.25 M NaOH solution to develop the ion-induced latent tracks. The detectors' surfaces have been analysed by Optical Microscopy (OM) and studied with the proposed method based on the measurements of both diameter and mean gray value of the ion-etched pits. The results are motivated by the future applications of these polymeric foils in the detection of charged particles in “harsh” environments, characterized by high dose and high radiation damage, e.g., in fusion experiments or in the diagnostic of plasma generated by lasers. A strong correlation between tracks’ characteristics (diameter and grayness) and the energy of the backscattered Cu ions has been obtained and empirical relationships between them are presented
Distribution of lithium in doped nuclear pores of polyethylene terephthalate by neutron depth profiling
No full textMultilayered Cu–Ti deposition on silicon substrates for chemiresistor applications
No full textOn the perspective to develop CuO–TiO2 MOS, multilayered Cu and Ti thin layers were alternatively deposited on silicon wafers using 25 keV Ar + ion beam sputtering and, subsequently, oxidized by thermal annealing in air at 400 °C for 24 h. The deposited films have variable ratios of the Cu and Ti % at. One of the main goal is to obtain such multilayers avoiding the presence of Cu–Ti–O compounds. The samples were characterized in terms of composition (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations). In particular, SIMS maps allows to observe the spatial distribution and thickness of each phase of the Cu/Ti multilayers, and further to observe Cu diffusion and mixing with Ti, as well as phase separation of CuO and TiO2 in the samples. The reasons of this effect represent an open issue that has to investigated, in order to improve the MOS fabrication
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Laser-generated nanoparticles to change physical properties of solids, liquids and gases
No full textSynthesis of nanoparticles was possible employing a Nd: YAG pulsed laser at fundamental harmonic. The production of nanoparticles in water depends mainly on the laser parameters (pulse duration, energy, wavelength), the irradiation conditions (focal spot, repetition rate, irradiation time) and the medium where the ablation occurs (solid target, water, solution concentration). The nanoparticles can be introduced in solids, liquids or gases to change many physical characteristics. The optical properties of polymers and solutions, the wetting ability of liquids, the electron density of laser-generated plasma, represent some examples that can be controlled by the concentration of metallic nanoparticles (Au, Ag, Ti, Cu). Some bio-medical applications will be presented and discussed
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