Search results for "Matrix"
showing 10 items of 3205 documents
Multiplicative cases from additive cases: Extension of Kolmogorov–Feller equation to parametric Poisson white noise processes
2007
Abstract In this paper the response of nonlinear systems driven by parametric Poissonian white noise is examined. As is well known, the response sample function or the response statistics of a system driven by external white noise processes is completely defined. Starting from the system driven by external white noise processes, when an invertible nonlinear transformation is applied, the transformed system in the new state variable is driven by a parametric type excitation. So this latter artificial system may be used as a tool to find out the proper solution to solve systems driven by parametric white noises. In fact, solving this new system, being the nonlinear transformation invertible, …
Vibrational spectra and force constants of symmetric tops
1983
The infrared spectrum of H3SiI in the 800–1050 cm-1 region has been recorded with a resolution of 0·04 cm-1 and rotationally analysed. Features related to the Fermi resonance between v 5 and v 3 + v 6 and to the Coriolis x, y resonance between v 2 and v 5 have been explained, and a set of vibration-rotation parameters for the three bands has been determined by least-squares calculations, σ(J, K) = 9·4 × 10-3 cm-1. The Fermi resonance matrix element |W 356| is found to be 3·7859(7) cm-1 and the vibrational frequencies are v 2 0 = 904·551(1), v 5 0 = 941·0746(8) and (v 3 + v 6)0 = 953·688(3) cm-1. The anharmonicity constant, x 36 = -1·745(9) cm-1, has been determined. Comparison is made with …
Multinucleated giant cells in the implant bed of bone substitutes are foreign body giant cells-New insights into the material-mediated healing process
2017
In addition to macrophages, multinucleated giant cells (MNGCs) are involved in the tissue reaction to a variety of biomaterials. Especially in the case of bone substitute materials it has been assumed that the MNGCs are osteoclasts, based on the chemical and physical similarity of many materials to the calcified matrix and the bony environment in which they are used. However, many studies indicate that these cells belong to the cell line of the foreign body giant cells (FBGCs), which are of "inflammatory origin", although they have been shown to possess both a pro- and also anti-inflammatory phenotype. Moreover, no information is available about their role in the tissue reaction to bone sub…
Use of parallel computing to improve the accuracy of calculated molecular properties
1998
Calculation of electron correlation energy in molecules is unavoidable in accurate studies of chemical reactivity. However, these calculations involve, a computational effort several, even in the simplest cases, orders of magnitude larger than the computer power nowadays available. In this work the possibility of parallelize the calculations of the electron correlation energy is studied. The formalism chosen is the dressing of matrices in both distributed and shared memory parallel systems MIMD. Algorithms developed on PVM are presented, and the results are evaluated on several platforms. These results show that the parallel techniques are useful in order to decrease very appreciably the ti…
Raman spectroscopy of formic acid and its dimers isolated in low temperature argon matrices
2009
Raman spectroscopy combined with matrix isolation technique was employed to study formic acid monomer and its dimers. Nine fundamentals of the HCOOH monomer were identified. Additionally, the OH torsion overtone is observed and it is engaged in Fermi resonance with the δCOH mode. Several bands of the cyclic (C2h) dimer were identified and assigned. The less stable open form (Cs) of the dimer was also present in the experiment. Three intermolecular modes for the cyclic and one mode for the open dimer were found in the low frequency region. The experimental studies were supported by harmonic and anharmonic DFT calculations.
Photolysis of HCOOH monomer and dimer in solid argon: Raman characterization of in situ formed molecular complexes
2010
Raman spectroscopy combined with the matrix isolation technique was employed to study the 193-nm photodecomposition products of formic acid in an argon matrix. The Raman-active fundamentals belonging to the CO(2) + H(2) and CO + H(2)O photoproducts were assigned. Also, bands due to Fermi resonance between the stretching vibration (nu(1)) and the overtone of the bending mode (2nu(2)) of CO(2) were identified. Both ortho- and para-H(2) molecules were identified from their rotational lines S(0)(1) and S(0)(0), respectively. These bands appeared upon matrix annealing as well as after prolonged photolysis. Additionally, photolysis of FA dimers produces oxalic acid and its secondary photoproducts…
A new Frequency Domain Measure of Causality based on Partial Spectral Decomposition of Autoregressive Processes and its Application to Cardiovascular…
2019
We present a new method to quantify in the frequency domain the strength of directed interactions between linear stochastic processes. This issue is traditionally addressed by the directed coherence (DC), a popular causality measure derived from the spectral representation of vector autoregressive (AR) processes. Here, to overcome intrinsic limitations of the DC when it needs to be objectively quantified within specific frequency bands, we propose an approach based on spectral decomposition, which allows to isolate oscillatory components related to the pole representation of the vector AR process in the Z-domain. Relating the causal and non-causal power content of these components we obtain…
Random vibration of linear and nonlinear structural systems with singular matrices: A frequency domain approach
2017
Abstract A frequency domain methodology is developed for stochastic response determination of multi-degree-of-freedom (MDOF) linear and nonlinear structural systems with singular matrices. This system modeling can arise when a greater than the minimum number of coordinates/DOFs is utilized, and can be advantageous, for instance, in cases of complex multibody systems where the explicit formulation of the equations of motion can be a nontrivial task. In such cases, the introduction of additional/redundant DOFs can facilitate the formulation of the equations of motion in a less labor intensive manner. Specifically, relying on the generalized matrix inverse theory, a Moore-Penrose (M-P) based f…
Table of Periodic Properties of Fullerenes Based on Structural Parameters.
2004
The periodic table (PT) of the elements suggests that hydrogen could be the origin of everything else. The construction principle is an evolutionary process that is formally similar to those of Darwin and Oparin. The Kekulé structure count and permanence of the adjacency matrix of fullerenes are related to structural parameters involving the presence of contiguous pentagons p, q and r. Let p be the number of edges common to two pentagons, q the number of vertices common to three pentagons, and r the number of pairs of nonadjacent pentagon edges shared between two other pentagons. Principal component analysis (PCA) of the structural parameters and cluster analysis (CA) of the fullerenes perm…
Natural co-occurrence of mycotoxins in wheat grains from Italy and Syria
2014
This article describes the application of an analytical method for the detection of 25 mycotoxins in wheat grain based on simultaneous extraction using matrix solid-phase dispersion (MSPD) followed by liquid chromatography coupled to tandem mass spectrometry, a hybrid triple quadrupole-linear ion trap mass spectrometer (QTrapÒ). Information Dependent Acquisition (IDA), an extra confirmation tool for samples that contain the target mycotoxins, was used. The analysis of 40 Syrian and 46 Italian wheat grain sam- ples interestingly showed that Syrian samples were mainly contaminated with ochratoxin A and aflatox- ins, whereas Italian samples with deoxynivalenol and 15-acetyldeoxynivalenol. Emer…