Search results for "Decomposition"
showing 10 items of 766 documents
Quantifying brain tumor tissue abundance in HR-MAS spectra using non-negative blind source separation techniques
2012
Given high-resolution magic angle spinning (HR-MAS) spectra from several glial tumor subjects, our goal is to differentiate between tumor tissue types by separating the different sources that contribute to the profile of each spectrum. Blind source separation techniques are applied for obtaining characteristic profiles for necrosis, highly cellular tumor and border tumor tissue and providing the contribution (abundance) of each of these tumor tissue types to the profile of each spectrum. The problem is formulated as a non-negative source separation problem. Non-negative matrix factorization, convex analysis of non-negative sources and non-negative independent component analysis methods are …
Surface-directed spinodal decomposition in a thin-film geometry: A computer simulation
1994
The phase separation kinetics of a two-dimensional binary mixture at critical composition confined between (one-dimensional) straight walls which preferentially attract one component of the mixture is studied for a wide range of distancesD between the walls. Following earlier related work on semiinfinite systems, two choices of surface forces at the walls are considered, one corresponding to an incompletely wet state of the walls, the other to a completely wet state (forD→∞). The nonlinear Cahn-Hilliard-type equation, supplemented with appropriate boundary conditions which account for the presence of surfaces, is replaced by a discrete equivalent and integrated numerically. Starting from a …
Application of alternating projection method to ensure feasibility of shadowing cross-correlation models
2007
A novel procedure based on the alternating projection method to adjust experimental shadowing cross-correlation (SCC) matrices is proposed. Given an SCC matrix derived from any experimental model, this procedure finds the nearest diagonalisable correlation matrix. This adjustment allows a proper simulation of shadowing samples, since it produces correlation matrices for which Cholesky factorisation is feasible. Simulation results using this procedure for three different SCC models are compared and discussed.
Ray-Space-Based Multichannel Nonnegative Matrix Factorization for Audio Source Separation
2021
Nonnegative matrix factorization (NMF) has been traditionally considered a promising approach for audio source separation. While standard NMF is only suited for single-channel mixtures, extensions to consider multi-channel data have been also proposed. Among the most popular alternatives, multichannel NMF (MNMF) and further derivations based on constrained spatial covariance models have been successfully employed to separate multi-microphone convolutive mixtures. This letter proposes a MNMF extension by considering a mixture model with Ray-Space-transformed signals, where magnitude data successfully encodes source locations as frequency-independent linear patterns. We show that the MNMF alg…
The Role of Covalent Functionalization in the Thermal Stability and Decomposition of Hybrid Layered Hydroxides
2020
The room temperature synthesis of two Co-based hybrid layered hydroxides containing the same organic ligand (suberate [Sub]), one connected through purely electrostatic interactions (CoAl layered double hydroxide [LDH]), and the other covalently functionalized (α-CoII simonkolleite phase) has been carried out. The magnetic properties exhibit an acute difference in the magnetization temperatures (from ≈10 K for the CoAl-LDH to ≈55 K for the α-CoII). Moreover, the role of the covalent functionalization in the thermal stability and the decomposition has been investigated by a forefront characterization tool consisting of thermogravimetric analysis coupled with gas chromatography and mass spect…
An assessment of factors controlling N2O and CO2 emissions from crop residues using different measurement approaches
2017
Management of plant residues plays an important role in maintaining soil quality and nutrient availability for plants and microbes. However, there is considerable uncertainty regarding the factors controlling residue decomposition and their effects on greenhouse gas (GHG) emissions from the soil. This uncertainty is created both by the complexity of the processes involved and limitations in the methodologies commonly used to quantify GHG emissions. We therefore investigated the addition of two soil residues (durum wheat and faba bean) with similar C/N ratios but contrasting fibres, lignin and cellulose contents on nutrient dynamics and GHG emission from two contrasting soils: a low-soil org…
GDP Density Disparities in Old Europe: Theil Decomposition in Cross-Country Historical Perspective
2011
The political, social and economic aspects of Old Europe have experienced profound changes over the last century. The levels and variations of GDP provide a good, though partial, representation of these changes with specific reference to the economic development. According to historical data, GDP shows strong increases in Europe; among these countries also Italy. But, what can we say about the cross-country income inequality? In this paper, we analyze cross-country disparities of GDP density from 1870 to 2008 in fourteen western European countries. In particular, we use a Duro-Esteban decomposition of the Theil index to identify the separate contribution of GDP per capita and population den…
Influence of diamagnetic impurity on mid‐IR absorption in antiferromagnetic insulator NiO
2005
-1 was studied in polycrystalline Ni c Mg 1-c O solid solutions with c=0.99, 0.98, 0.97, 0.95, 0.90, 0.80, 0.70 and 0.60. The composition and temperature dependences of the absorption suggest that the band has magnetic origin re- lated to simultaneous excitation of two-magnons at the Brillouin-zone boundary and one phonon. -1 in polycrystalline NicMg1-cO solid solutions. Polycrystalline solid solutions NicMg1-cO (c=0.99, 0.98, 0.97, 0.95, 0.90, 0.80, 0.70 and 0.60) were prepared using ceramic technology from the appropriate amounts of aqueous solutions of Mg(NO3)2·6H2O and Ni(NO3)2·6H2O salts, which were mixed and slowly evaporated. The remaining dry 'flakes' were heated up to 500-600 oC to…
Crystal Structures and Thermal Behavior of Isostructural Bis(dibenzyldimethylammonium) Tetrachlorometallate [M = Mn(II), Co(II), Ni(II) and Zn(II)] S…
2007
Five isostructural bis(dibenzyldimethylammonium) tetrachlorometallate solvate complexes [M = Mn(II), Co(II), Ni(II) or Zn(II)] were crystallized from acetonitrile and/or methanol solutions. The crystal structures are compared to those of the analogous, isostructural copper compounds (X = Cl or Br) reported earlier. The complexes crystallize in the monoclinic space group P21/n with Z = 4, and unit cell dimensions of a ≈ 14.1, b ≈ 16.1, c ≈ 15.7 °A and β ≈ 108 - 109°. The asymmetric unit of these compounds contains one MCl4 2− anion, two Bz2Me2N+ cations in theW-conformation and one half of a disordered solvent molecule (acetonitrile or methanol). The geometry of the MCl4 2− anion is close to…
Nachweis des di-2-cyanoisopropylperoxides bei der zersetzung von azoisobuttersäuredinitril in gegenwart von sauerstoff
1970
Das Di-2-cyanoisopropylperoxid entsteht in etwa 5-proz. Ausbeute bei der Zersetzung von Azoisobuttersaredinitril unter Sauerstoff in Isobutyronitril als Losungsmittel. Thermisch zerfallt das Peroxid est oberhalb von 120°C mit mesbarer Geschwindigkeit in einer Reaktion erster Ordnung. Die Aktivierungsenergie, in Cumol als Losungsmittel, wurde zu 37,9 kcal · mol−1 bestimmt. Werte fur die Zerfallskonstante bei 140°C sind in Cumol 0,057 h−1, in tert-Butylbenzol 0,073 h−1, in Chlorbenzol 0,18 h−1 und in o-Dichlorbenzol 0,23 h−1. Di-2-cyanoisopropylperoxide is formed when azobisisobutyronitrile is decomposed under oxygen in isobutyronitrile as a solvent. The yield amounts to ca. 5%. Thermal decom…