Search results for " Dispersion"
showing 10 items of 280 documents
Particle Suspension in Vortexing Unbaffled Stirred Tanks
2016
Three-phase processes in which particle suspension has to be achieved in conjunction with gas dispersion are traditionally carried out in sparged, baffled stirred tanks. The operation of such tanks can suffer, however, from particles tending to block the sparger holes. A viable alternative might be provided by uncovered unbaffled stirred tanks (UUSTs), where gas self-injection can occur when the free-surface vortex reaches the impeller blades and gas bubbles begin to be ingested by the liquid. In this work, the particle suspension and liquid aeration performances in three-phase UUSTs were experimentally investigated and compared with relevant literature correlations concerning baffled syste…
Promuovere pratiche inclusive attraverso l’orientamento: una ricerca nel contesto palermitano.
2016
La ricerca, inserita all’interno del Programma PRIN dal titolo “Successo formativo, inclusione e coesione sociale: strategie innovative, ICT e modelli valutativi”, affronta l’orientamento come tematica cruciale per garantire una maggiore inclusione sociale e per contrastare la dispersione scolastica.
Periodic time-domain modulation for the electrically tunable control of optical pulse train envelope and repetition rate multiplication
2012
An electrically tunable system for the control of optical pulse sequences is proposed and demonstrated. It is based on the use of an electrooptic modulator for periodic phase modulation followed by a dispersive device to obtain the temporal Talbot effect. The proposed configuration allows for repetition rate multiplication with different multiplication factors and with the simultaneous control of the pulse train envelope by simply changing the electrical signal driving the modulator. Simulated and experimental results for an input optical pulse train of 10 GHz are shown for different multiplication factors and envelope shapes. © 2006 IEEE.
Raman spectroscopy study of β-irradiated silica glass
2003
International audience; Natural and synthetic silica glass samples with different OH content have been submitted to β-irradiation at different doses from 106 to 5 × 109 Gy in a Van de Graaff accelerator. Structural changes under irradiation have been analyzed by Raman spectroscopy. The main findings are: (i) a decrease of the Si–O–Si angular dispersion and the average Si–O–Si angle as a function of dose and (ii) an increase of number of three-membered SiO4 ring concentration during irradiation. These results show therefore that purely electronic excitation from β-irradiation induces in a-SiO2 small but significant structural changes of the SiO4 membered ring statistics (size and dispersion)…
Intermolecular interaction energies and magnetic properties of spin-isolated multinuclear CuII complexes
2020
Dinuclear CuII complexes with 3,5-dinitrobenzoates and 2,2′-bipyridine (2) or 1,10-phenanthroline (3) were synthesized and characterized. A complete energy framework analysis using the HF/3-21G energy model was performed which found that dispersion forces and C—H...O interactions are responsible for the crystal structure features. The magnetic properties of the complexes show a weak magnetic exchange between spins, resulting in low exchange constants of −2.72 (1) cm−1 and −1.10 (1) cm−1 for complexes (2) and (3), respectively. This results from the low overlap between magnetic orbitals induced by 3,5-dinitrobenzoate bridges and the arrangement of the magnetic orbitals. Consequently, the din…
The gaia-eso survey: dynamical analysis of the l1688 region in ophiuchus
2016
The Gaia ESO Public Spectroscopic Survey (GES) is providing the astronomical community with high-precision measurements of many stellar parameters including radial velocities (RVs) of stars belonging to several young clusters and star-forming regions. One of the main goals of the young cluster observations is to study of their dynamical evolution and provide insight into their future, revealing if they will eventually disperse to populate the field, rather than evolve into bound open clusters. In this paper we report the analysis of the dynamical state of L1688 in the $\rho$~Ophiuchi molecular cloud using the dataset provided by the GES consortium. We performed the membership selection of t…
Sigma-convergence in the OECD: Transitional Dynamics or Narrowing Steady State Differences?
2002
The empirical literature of growth has steadly improved the econometric methods used mainly to address the effect of cross-country heterogeneity in the estimated convergence rate. In this paper, we highlight an important implication of this process of econometric refinement that has so far received little attention. We show that the picture that emerges from models that allow for generalised heterogeneity changes our view of the process of convergence within the OECD. Estimation methods that allow for non or partial heterogeneity stress the importance of transitional dynamics in the process of convergence. Thus sigma-convergence is mostly accounted for by beta-convergence. On the contrary, …
CGCG 480-022: A Distant Lonesome Merger?
2006
[EN]We present a complete analysis, which includes morphology, kinematics, stellar populations, and N-body simulations, of CGCG 480-022, the most distant (cz = 14,317 km s-1) isolated galaxy studied so far in such detail. The results all support the hypothesis that this galaxy has suffered a major merger event with a companion of ~0.1 times its mass. Morphology reveals the presence of a circumnuclear ring and possibly further ring debris. The radial velocity curve looks symmetrical, while the velocity dispersion increases with radius, reaching values that do not correspond to a virialized system. Moreover, this galaxy deviates significantly from the fundamental plane and the Faber-Jackson r…
The Second APOKASC Catalog: The Empirical Approach
2018
We present a catalog of stellar properties for a large sample of 6676 evolved stars with APOGEE spectroscopic parameters and \textit{Kepler} asteroseismic data analyzed using five independent techniques. Our data includes evolutionary state, surface gravity, mean density, mass, radius, age, and the spectroscopic and asteroseismic measurements used to derive them. We employ a new empirical approach for combining asteroseismic measurements from different methods, calibrating the inferred stellar parameters, and estimating uncertainties. With high statistical significance, we find that asteroseismic parameters inferred from the different pipelines have systematic offsets that are not removed b…
Dispersion Forces and Counterintuitive Steric Effects in Main Group Molecules: Heavier Group 14 (Si-Pb) Dichalcogenolate Carbene Analogues with Sub-9…
2013
The synthesis and spectroscopic and structural characterization of an extensive series of acyclic, monomeric tetrylene dichalcogenolates of formula M(ChAr)2 (M = Si, Ge, Sn, Pb; Ch = O, S, or Se; Ar = bulky m-terphenyl ligand, including two new acyclic silylenes) are described. They were found to possess several unusual features-the most notable of which is their strong tendency to display acute interligand, Ch-M-Ch, bond angles that are often well below 90°. Furthermore, and contrary to normal steric expectations, the interligand angles were found to become narrower as the size of the ligand was increased. Experimental and structural data in conjunction with high-level DFT calculations, in…