Search results for "Density"
showing 10 items of 4402 documents
A high-resolution PET demonstrator using a silicon "magnifying glass".
2021
Abstract To assist ongoing investigations of the limits of the tradeoff between spatial resolution and noise in PET imaging, several PET instruments based on silicon-pad detectors have been developed. The latest is a segment of a dual-ring device to demonstrate that excellent reconstructed image resolution can be achieved with a scanner that uses highresolution detectors placed close to the object of interest or surrounding a small field-of-view in combination with detectors having modest resolution at larger radius. The outer ring of our demonstrator comprises conventional BGO block detectors scavenged from a clinical PET scanner and located at a 500 mm radius around a 50 mm diameter field…
A geometric street scattering channel model for car-to-car communication systems
2011
This paper presents a geometric street scattering channel model for car-to-car (C2C) communication systems under line-of-sight (LOS) and non-LOS (NLOS) propagation conditions. Starting from the geometric model, we develop a stochastic reference channel model, where the scatterers are uniformly distributed in rectangles in the form of stripes parallel to both sides of the street. We derive analytical expressions for the probability density functions (PDFs) of the angle-of-departure (AOD) and the angle-of-arrival (AOA). We also investigate the Doppler power spectral density (PSD) and the autocorrelation function (ACF) of the proposed model, assuming that the mobile transmitter (MT) and the mo…
Performance Analysis of M-DPSK Modulation over Fast-Hoyt Fading Channels under Non-Isotropic Scattering Conditions
2021
In this paper, we analyze the symbol error probability (SEP) performance of M-ary differential phase shift keying (M-DPSK) modulation schemes over frequency-flat fast-varying Hoyt multipath fading channels. Assuming general non-isotropic scattering conditions, we first derive a finite-range integral expression for the probability density function (PDF) of the phase difference between two non-isotropic Hoyt vectors perturbed by additive white Gaussian noise (AWGN). Based upon the theory of M-DPSK modulation and the obtained PDF formula, the SEP of M-DPSK and its corresponding asymptotic behavior in non-isotropic fast-Hoyt fading channels are derived. Specifically, a double semi-finite range …
X-ray and DFT-calculated structures of a vanadyl Schiff base complex: (methanol-κO)[2-methoxy-6-({2-[(2-oxido-3-methoxybenzylidene)amino]benzyl}imino…
2012
The central VVatom in the title mononuclear oxovanadium complex, [VO(C23H20N2O4)(CH3OH)]·H2O, has a distorted octahedral coordination. Two N atoms and two O atoms of the Schiff base define the base of the bipyramid and two O atoms are in the apical positions, one from vanadyl and the second from methanol. Density functional theory (DFT) calculations were performed for the title complex and its ligand to compare their geometry in the solid and gas phases. Additional analyses were made of the changes in the geometry of the ligand during complex formation. The HOMA (harmonic oscillator model of aromaticity) descriptor of π-electron delocalization was calculated to estimate the aromaticity of t…
A vanadyl Schiff base complex: {2,2'-[1,1'-(o-phenylenedinitrilo)bis(ethan-1-yl-1-ylidene)]diphenolato}oxovanadium(IV).
2011
The green crystals of the title compound, [V(C(22)H(18)N(2)O(2))O], represent a mononuclear oxovanadium complex. The central V(IV) centre has a distorted square-pyramidal coordination. Two N atoms and two O atoms of the Schiff base ligand define the base of the pyramid, and the oxide O atom is in the apical position. Density functional theory (DFT) calculations were performed to analyse the changes in the geometry of the ligand during the complex formation. The most significant changes are observed in the values of the torsion angles in the vicinity of the donor N atoms. The HOMA index (Harmonic Oscillator Model of Aromaticity) has been calculated to compare the aromaticity of the benzene r…
Data on physical and chemical characterization of wood combustion products derived at cogeneration power plants
2021
The data presented in this article are related to the research paper “Granulation of fly ash and biochar with organic lake sediments – A way to sustainable utilization of waste from bioenergy production” [1] in the context of waste material investigation and possible valorization instead of disposal. This article provides a comprehensive chemical and physical characterization of wood combustion products – fly ashes, bottom ashes, mixed ashes and biochar. Multiple analytical techniques and methodology were exploited to investigate the composition of wood combustion products, among them a loss on ignition, potentiometry, colorimetry, X-ray diffractometry, X-ray fluorescence spectrometry, indu…
BICKEL–ROSENBLATT TEST FOR WEAKLY DEPENDENT DATA
2012
The aim of this paper is to analyze the Bickel–Rosenblatt test for simple hypothesis in case of weakly dependent data. Although the test has nice theoretical properties, it is not clear how to implement it in practice. Choosing different band-width sequences first we analyze percentage rejections of the test statistic under H0 by some empirical simulation analysis. This can serve as an approximate rule for choosing the bandwidth in case of simple hypothesis for practical implementation of the test. In the recent paper [12] a version of Neyman goodness-of-fit test was established for weakly dependent data in the case of simple hypotheses. In this paper we also aim to compare and discuss the …
The effect of osseodensification on implant stability and bone density: A prospective observational study.
2019
Background The aims of this study were to evaluate the effect of implant site preparation in low-density bone using osseodensification method in terms of implant stability changes during the osseous healing period and peri-implant bone density using CBCT. Material and Methods This prospective observational clinical study included 24 patients who received 46 dental implants that were installed in low-density bone using the osseodensification method. CBCT was used to measure the bone density pre- and postoperatively and implant stability was measured using Periotest® immediately after implant insertion and then after 6 weeks and 12 weeks postoperatively. The data were analyzed using paired t-…
Weak aurophilic interactions in a series of Au(III) double salts.
2015
In this work, several new examples of rare AuIII⋯AuIII aurophilic contacts are reported. A series of gold(III) double salts and complexes, viz. [AuX2(L)][AuX4] (L = 2,2′-bipyridyl, X = Cl 1, Br 2; L = 2,2′-bipyrimidine, X = Cl 3, Br 4; L = 2,2′-dipyridylamine, X = Cl 5, Br 6), [AuX3(biq)] (biq = 2,2′-biquinoline, X = Cl 7, Br 8), [LH][AuX4] (L = 2,2′-bipyridyl, X = Cl 9; L = 2,2′-bipyrimidine, X = Cl 12; L = 2,2′-dipyridylamine, X = Cl 14, Br 15; L = 2,2′-biquinoline, X = Cl 17, Br 18), [AuBr2(bpy)]2[AuBr4][AuBr2] 10, [AuCl2(bpm)][AuCl2] 11, (bpmH)2[AuBr4][AuBr2] 13, and (dpaH)[AuBr2] 16 (1, 2, and 7 were reported earlier) was synthesized by coordination of a particular ligand to the AuIII …
Experimental approach for testing the uncoupling between cardiovascular variability series
2002
In cardiovascular variability analysis, the significance of the coupling between two series is commonly assessed by defining a zero level on the magnitude-squared coherence (MSC). Although the use of the conventional value of 0.5 does not consider the dependence of MSC estimates on the analysis parameters, a theoretical threshold Tt is available only for the weighted covariance (WC) estimator. In this study, an experimental threshold for zero coherence Te was derived by a statistical test from the sampling distribution of MSC estimated on completely uncoupled time series. MSC was estimated by the WC method (Parzen window, spectral bandwidth B = 0.015, 0.02, 0.025, 0.03 Hz) and by the parame…