Search results for "solution"
showing 10 items of 5638 documents
Generalized wavelets design using Kernel methods. Application to signal processing
2013
Abstract Multiresolution representations of data are powerful tools in signal processing. In Harten’s framework, multiresolution transforms are defined by predicting finer resolution levels of information from coarser ones using an operator, called the prediction operator, and defining details (or wavelet coefficients) that are the difference between the exact values and the predicted values. In this paper we present a multiresolution scheme using local polynomial regression theory in order to design a more accurate prediction operator. The stability of the scheme is proved and the order of the method is calculated. Finally, some results are presented comparing our method with the classical…
Polynuclear copper(II) complexes with hexadentate Schiff base directed by the counter ion. Syntheses, crystal structures and magnetic properties
2018
Abstract Four new complexes, [Cu 9 L 6 ( µ 3 -ClO 4 ) 2 ](ClO 4 ) 4 ·4CHCl 3 1 , [Cu 3 L 2 (H 2 O) 2 ](ClO 4 ) 2 ·3H 2 O 2 , [Cu 6 L 4 (N 3 ) 2 ](ClO 4 ) 2 3 and [Cu 2 L(CH 3 COO) 2 ] 4 , where H 2 L stands for the Schiff base N , N ′-bis[(2-hydroxybenzilideneamino)-propyl]-piperazine, were obtained and structurally characterized. Compounds 1 , 2 and 3 contain the Cu 3 L 2 2+ entities in which L 2− acts in an unsymmetrical mode with N 3 O donor set wrapped around marginal copper(II) and with the remained NO sets bound to the central copper ion. The marginal copper(II) ions are in distorted square pyramidal environment, whereas that of the central one is square planar. In 1 , the peripheral …
A Series of MIICuII3 Stars (M = Mn, Ni, Cu, Zn) Exhibiting Unusual Magnetic Properties
2014
The work in this report describes the syntheses, electrospray ionization mass spectromtery, structures, and experimental and density functional theoretical (DFT) magnetic properties of four tetrametallic stars of composition [M(II)(Cu(II)L)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn) derived from a single-compartment Schiff base ligand, N,N'-bis(salicylidene)-1,4-butanediamine (H2L), which is the [2 + 1] condensation product of salicylaldehyde and 1,4-diaminobutane. The central metal ion (Mn(II), Ni(II), Cu(II), or Zn(II)) is linked with two μ2-phenoxo bridges of each of the three [Cu(II)L] moieties, and thus the central metal ion is encapsulated in between three [Cu(II)L] units. …
Dichlorovanadium (IV) complexes with salen-type ligands for ethylene polymerization
2008
Vanadium complexes with tetradentate salen-type ligands were first time explored in ethylene polymerizations. The effects of the vanadium complex structure, the alkyl aluminum cocatalysts type (EtAlCl2, Et2AlCl, Et3Al, and MAO), and the polymerization conditions (Al/V molar ratio, temperature) on polyethylene yield were explored. It was found that EtAlCl2 in conjunction with investigated vanadium complexes produced the most efficient catalytic systems. It was shown, moreover, that the structural changes of the tetradentate salen ligand (type of bridge which bond donor nitrogen atoms and type of substituent on aryl rings) affected activity of the catalytic system. The complexes containing li…
Ethylenebis(5-chlorosalicylideneiminato)vanadium dichloride immobilized on MgCl2 -based supports as a highly effective precursor for ethylene polymer…
2009
Ethylenebis(5-chlorosalicylideneiminato)vanadium dichloride supported on MgCl2(THF)2 or on the same carrier modified by EtnAlCl3−n, where n = 1–3, was used in ethylene polymerization in the presence of MAO or a common alkylaluminium compounds as a cocatalyst. The support type alter vanadium loading and also change the characteristic of the catalytic active sites. Et2AlCl is the best activator for a catalyst which has been immobilized on a nonmodified support, whereas the systems which contain a carrier which has been modified by an organoaluminium compound reveal the highest activity in conjunction with MAO. That difference, together with different temperature effects on polymerization effi…
Preparing Teachers for Teaching Probability Through Problem Solving
2018
In this paper we introduce the idea of solving problems by simulation with didactical intention. Based on this idea, we analyse the way we prepare the teachers to teach solving probability problems by simulation, in distinguishing whether the teaching is offered to prospective elementary teachers or secondary school teachers. The process of solving probability problems is seen as an inquiry process, which uses simulation as a resolution method with heuristic content, so that the preparation of teacher is then based on this approach. Therefore, prospective teachers should have the opportunities to learn about probability problems, about the process of solving probability problems, and about …
Gamma-ray position reconstruction in large lanthanum-halide crystals with SiPM readout: analytical vs. neural-network algorithms
2019
The main objective of this research was to achieve an excellent gamma-ray position reconstruction with very large monolithic scintillation crystals coupled to pixelated silicon photosensors. Analyzing the scintillation-light distribution measured along the SiPM-pixels one can get a sub-pixel accuracy for the position reconstruction. The quality of the latter depends on both the characteristics of the crystal-photosensor assembly, and the goodness of the algorithm used to reconstruct the gamma-ray hit location. We have carried out a systematic study for 511 keV gamma-rays using three different crystal thicknesses of 10 mm, 20 mm and 30 mm, all of them with planar geometry and a base size of …
<title>Surface temperature retrieval from MODIS data</title>
2001
12 MODIS (Moderate Resolution Imaging Spectroradiometer) was launched on board the NASA's Terra Earth Observing System (EOS AM-1) Satellite on December 18, 1999. We propose in this work operative split-window algorithms for retrieving sea surface temperature (SST) and land surface temperature (LST) using MODIS data. In order to attain our goal, the MODTRAN 3.5 radiative transfer code was used to predict radiances for MODIS channels 31 and 32. To analyze atmospheric effects, a set of radiosoundings was used to cover the variability of surface temperature and water vapor concentration on a worldwide scale. These simulated data were split into two sets which have very similar distributions in …
Land Surface Temperature From the Advanced Along-Track Scanning Radiometer: Validation Over Inland Waters and Vegetated Surfaces
2009
The land surface temperature (LST) product of the Advanced Along-Track Scanning Radiometer (AATSR) was validated with ground measurements at the following two thermally homogeneous sites: Lake Tahoe, CA/NV, USA, and a large rice field close to Valencia, Spain. The AATSR LST product is based on the split-window technique using the 11- and 12- mum channels. The algorithm coefficients are provided for 13 different land-cover classes plus one lake class (index i). Coefficients are weighted by the vegetation-cover fraction (f). In the operational implementation of the algorithm, i and f are assigned from a global classification and monthly fractional vegetation-cover maps with spatial resolution…
Periodic solutions for a class of second-order Hamiltonian systems
2005
Multiplicity results for an eigenvalue second-order Hamiltonian system are investigated. Using suitable critical points arguments, the existence of an exactly determined open interval of positive eigenvalues for which the system admits at least three distinct periodic solutions is established. Moreover, when the energy functional related to the Hamiltonian system is not coercive, an existence result of two distinct periodic solutions is given.© 2005 Texas State University - San Marcos.