Iterrative correction of measurement with averaging of dithered samples

Self-calibration techniques could eliminate measurement errors caused by time changes and component aging. For ADC performance enhancement also averaging is necessary. In the paper the iterative measurement error correction method is presented in combination with averaging. Dither theory for Gaussian noise has been used for exhibition of averaging abilities in ADC characteristic improvement. Experimental ENOB value improvement is more than 1.5 bit

Mechanochemical synthesis of nanocrystalline lead selenide

Mechanochemical synthesis of lead selenide PbSe nanoparticles has been performed by high-energy milling of lead and selenium powder in a planetary ball mill Pulverisette 6 (Fritsch, Germany) and in an industrial eccentric vibratory mill ESM 654 (Siebtechnik GmbH, Germany). Structural properties of the synthesized lead selenide were characterized by X-ray diffraction, which confirms crystalline nature of PbSe nanoparticles (JCPDS 6-354). The average size of PbSe crystallites of 37 nm was calculated from XRD data by Williamson-Hall method. The methods of particle size distribution analysis, specific surface area measurement, scanning electron microscopy and transmission electron microscopy were used for characterization of surface, mean particle size, and morphology of PbSe. An application of industrial mill verified a possibility of the synthesis of a narrowband-gap semiconductor PbSe at ambient temperature and in a relatively short reaction time

Analyses of Quantization Noise Spectrum for Multiresolution Quantization of Harmonic Signal

Abstract

Nanogranular MgB2 thin films on SiC buffered Si substrates prepared by in-situ method

MgB2 thin films were deposited on SiC buffered Si substrates by sequential electron beam evaporation of B-Mg bilayer followed by in-situ annealing. The application of a SiC buffer layer enables the maximum annealing temperature of 830 C. The Transmission Electron Microscopy analysis confirms the growth of a nanogranular MgB2 film and the presence of a Mg2Si compound at the surface of the film. The 150-200 nm thick films show a maximum zero resistance critical temperature TC0 above 37 K and a critical current density JC ~ 106 A/cm2 at 11K.Comment: 7 pages, 6 figures, submitted to Applied Physics Letter

Optical spectra obtained from amorphous films of rubrene: Evidence for predominance of twisted isomer

In order to investigate the optical properties of rubrene we study the vibronic progression of the first absorption band (lowest \pi -> \pi^* transition). We analyze the dielectric function of rubrene in solution and thin films using the displaced harmonic oscillator model and derive all relevant parameters of the vibronic progression. The findings are supplemented by density functional calculations using B3LYP hybrid functionals. Our theoretical results for the molecule in two different conformations, i.e. with a twisted or planar tetracene backbone, are in very good agreement with the experimental data obtained for rubrene in solution and thin films. Moreover, a simulation based on the monomer spectrum and the calculated transition energies of the two conformations indicates that the thin film spectrum of rubrene is dominated by the twisted isomer.Comment: 7 pages, 6 figure

Superplastična deformacija Al-Al4C3 kompozita

Deformation of the Al-Al4C3 composites with different volume fraction of Al-Al4C3 phase was investigated at different temperatures (293 - 723 K) and different strain rates (2,5 * 10-5 s-1 do 1,0 * 10-1 s-1). At temperatures 673 - 723 K and at the highest strain rate of 1,0 * 10-1 s-1, a significant ductility increase was observed. TEM analysis suggests the onset of superplasticity may be the result of dynamic grain polygonization, grain slip and rotation, partial recrystallization and dislocation creep in the tested system, which is known as strain induced dynamic recovery. Increase of the volume fraction of secondary phase in the studied composite resulted in a shift from slip on grain boundaries controlled mechanism to the grain rotation controlled deformation mechanism.Istraživana je deformacija Al-Al4C3 kompozita različitog volumnog udjela Al-Al4C3 faze kod različitih temperatura (od 293 do 723 K) i brzina deformacije (od 2,5 * 10-5 s-1 do 1,0 * 10-1 s-1). Kod temperatura od 673 do 723 K i najviše brzine deformacije od 1,0 * 10-1 s-1 zapaženo je značajno povećanje kovkosti. TEM analiza ukazuje da početak superplastičnosti može biti rezultat dinamičke poligonizacije zrna, klizanja i rotacije zrna, djelomične rekristalizacije i puzanja dislokacija u istraživanom sustavu, što je poznato kao deformacijom inducirano dinamičko oporavljanje. Porast volumnog udjela sekundarne faze u istraživanom kompozitu rezultirao je promjenom kontrolnog mehanizma deformacije od klizanja po granicama zrna do rotacije zrna