Search results for "Radius"
showing 10 items of 708 documents
Room-Temperature Electrical Characteristics of Pd∕SiC Diodes with Embedded Au Nanoparticles at the Interface
2010
We investigate the effects of localized controlled nanometric inhomogeneities, represented by Au nanoparticles, on the electrical properties of Pd/SiC Schottky diodes. In particular, we investigate the effects of the nanoparticle radius R on the current-voltage characteristics. The main result concerns the strong dependence of the effective Schottky barrier height of the Pd/SiC contact on R, giving a practical technique to tailor, in a wide range, such a barrier height by simply changing the process parameters during the diode preparation. Then, from a basic understanding point of view, such data allow us to test the Tung model describing the effects of inhomogeneities on the electrical pro…
Three-dimensional dynamic light scattering
1999
Abstract We describe the employment of a novel light-scattering scheme for the decorrelation of multiple scattering in strongly turbid samples. The three-dimensional scheme, which has been proposed already theoretically, shows certain advantages compared with the two-colour apparatus, which is commercially available. We describe our set-up in detail; features are the use of modern semiconductor laser diodes and contemporary single-mode fibre receivers. We show experimentally that the optimal signal-to-noise ratio (or intercept) β opt = 0.20, which is obtainable with our set-up, can be quantitatively calculated from the measured uncertainties in the alignment. In particular, we give a detail…
Three 2,5-dialkoxy-1,4-diethynylbenzene derivatives
2008
2,5-Diethoxy-1,4-bis[(trimethylsilyl)ethynyl]benzene, C20H30O2Si2, (I), constitutes one of the first structurally characterized examples of a family of compounds, viz. the 2,5-dialkoxy-1,4-bis[(trimethylsilyl)ethynyl]benzene derivatives, used in the preparation of oligo(phenyleneethynylene)s via Pd/Cu-catalysed cross-coupling. 2,5-Diethoxy-1,4-diethynylbenzene, C14H14O2, (II), results from protodesilylation of (I). 1,4-Diethynyl-2,5-bis(heptyloxy)benzene, C24H34O2, (III), is a long alkyloxy chain analogue of (II). The molecules of compounds (I)–(III) are located on sites with crystallographic inversion symmetry. The large substituents either in the alkynyl group or in the benz…
Simplified analytical models for compressed concrete columns confined by FRP and FRCM system
2017
In order to consider the response of concrete columns confined by FRP and FRCM system, proper models have to be formulated. In this context the present paper shows a generalized criterion for the determination of the increase in strength, in ductility and in dissipated energy for varying corner radius ratio of the cross section and fiber volumetric ratio. The procedure is based on the best fitting of several experimental data and unlike the usual empirical approaches available in the literature, the proposed technique relates the confinement effectiveness to a single parameter representative of the relative stiffness between the original concrete core and the reinforcement system. Furthermo…
Technical Note: Sensitivity of 1-D smoke plume rise models to the inclusion of environmental wind drag
2010
Abstract. Vegetation fires emit hot gases and particles which are rapidly transported upward by the positive buoyancy generated by the combustion process. In general, the final vertical height that the smoke plumes reach is controlled by the thermodynamic stability of the atmospheric environment and the surface heat flux released by the fire. However, the presence of a strong horizontal wind can enhance the lateral entrainment and induce additional drag, particularly for small fires, impacting the smoke injection height. In this paper, we revisit the parameterization of the vertical transport of hot gases and particles emitted from vegetation fires, described in Freitas et al. (2007), to in…
Primary and secondary distributions after a small-amplitude potential step at disk electrode coated with conducting film
2011
Abstract The set of equations and boundary conditions for the “primary potential/current distribution” after a small-amplitude potential step has been analyzed for a film-coated disk electrode in contact with an electrolyte. The solution of these equations provides the overall short-time resistance of this system, Rtot, which is determined by the short-time resistance of the electrolyte solution in contact with the bare disk electrode, Rs, and the short-time film resistance to the current passage in the normal direction, R f = L f / κ f π r o 2 (ro, disk radius; Lf, film thickness; κf, its specific conductivity). The deviation of Rtot from the sum of these resistances, Rs + Rf, originates f…
Moleküldimensionen von polymeren in verschiedenen lösungsmitteln auf grund hydrodynamischer messungen
1960
Ein fraktioniertes Polystyrol vom Molekulargewicht Mw ≈ 540000 wurde in Chloroform, Toluol, Methylathylketon und Cyclohexan sowie in drei Mischungen von Toluol und Methylathylketon untersucht. Da das Chloroform ein gutes, das Cyclohexan dagegen ein Θ-Losungsmittel fur Polystyrol darstellt, nehmen die Dimensionen des Fadenmolekuls beim Ubergang zwischen den Losungsmitteln ab. Mit den Knaueldimensionen andern sich Reibung und Viskositat des Polystyrols. Messungen der Sedimentationskonstanten, der Diffusionskonstanten, der Viskositatszahl sowie der Dichte und der Zahigkeit fur die gemischten Losungsmittel wurden ausgefuhrt. Die Ergebnisse der Messungen werden benutzt, um aus der Viskositatsthe…
Solution behavior of ethylcellulose in organic solvents
2007
Ethylcellulose has been investigated by osmotic pressure, sedimentation-diffusion, and light scattering measurements in dilute solutions of acetone, ethylacetate, 2-butanol, n-butylchloride, and benzene. Combining the results of different measuring techniques allowed the recognition and elimination of the influence of microgels present in the solution. The observed second virial coefficients are high as compared with those of the vinyl polymers and do not show a pronounced dependence on the type of solvent. On the other hand, the radius of gyration is nearly proportional to the root of the molecular weight. This behavior is discussed in connection with results on other cellulose ethers repo…
SVEP and local spectral radius formula for unbounded operators
2014
In this paper we study the localized single valued extension property for an unbounded operator T. Moreover, we provide sufficient conditions for which the formula of the local spectral radius holds for these operators.
Multi-epoch VLTI-PIONIER imaging of the supergiant V766 Cen
2017
Context. The star V766 Cen (=HR 5171A) was originally classified as a yellow hypergiant but lately found to more likely be a 27-36 M red supergiant (RSG). Recent observations indicated a close eclipsing companion in the contact or common-envelope phase. Aims. Here, we aim at imaging observations of V766 Cen to confirm the presence of the close companion. Methods. We used near-infrared H-band aperture synthesis imaging at three epochs in 2014, 2016, and 2017, employing the PIONIER instrument at the Very Large Telescope Interferometer (VLTI). Results. The visibility data indicate a mean Rosseland angular diameter of 4.1 ± 0.8 mas, corresponding to a radius of 1575 ± 400 R. The data show an ex…