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Wyszukujesz frazę "Vidal, J." wg kryterium: Autor


Tytuł:
Precise determination of HPGe detector efficiency for gamma spectrometry measurements of environmental samples with variable geometry and density
Autorzy:
Barrera, M.
Casas-Ruiz, M.
Alonso, J. J.
Vidal, J.
Powiązania:
https://bibliotekanauki.pl/articles/146350.pdf
Data publikacji:
2017
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
efficiency calibration
environmental radioactivity
gamma spectrometry
geometric dependence of the efficiency
self-attenuation corrections
Opis:
A methodology to determine the full energy peak efficiency (FEPE) for precise gamma spectrometry measurements of environmental samples with high-purity germanium (HPGe) detector, valid when this efficiency depends on the energy of the radiation E, the height of the cylindrical sample H, and its density ρ is introduced. The methodology consists of an initial calibration as a function of E and H and the application of a self-attenuation factor, depending on the density of the sample ρ, in order to correct for the different attenuation of the generic sample in relation to the measured standard. The obtained efficiency can be used in the whole range of interest studied, E = 120–2000 keV, H = 1–5 cm, and ρ = 0.8–1.7 g/cm3, being its uncertainty below 5%. The efficiency has been checked by the measurement of standards, resulting in a good agreement between experimental and expected activities. The described methodology can be extended to similar situations when samples show geometric and compaction differences.
Źródło:
Nukleonika; 2017, 62, 1; 47-59
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
THE RELATIONSHIP BETWEEN PHYSICAL FITNESS AND ACADEMIC PERFORMANCE IN ADOLESCENTS FROM THE BALEARIC ISLANDS
Autorzy:
Bestard, V.
Cantallops, J.
Vidal-Conti, J.
Powiązania:
https://bibliotekanauki.pl/articles/449112.pdf
Data publikacji:
2017
Wydawca:
Politechnika Opolska. Wydział Wychowania Fizycznego i Fizjoterapii
Tematy:
physical fitness
physical activity
academic performance
adolescents
Opis:
The aim of this study is to see if there are significant relationships between different variables of physical condition and academic performance. Most literature shows that a relationship does exist, mainly emphasizing maximal oxygen consumption and academic performance. With regard to the other variables, more differences can be found. A total of 79 students participated in the study from the island of Majorca (Spain), ranging in age from 12.5 to 14.5 years. Students passed fitness tests, which were compared with their academic results. The results show a significant positive relationship between BMI and hand grip strength and significant negative relationships between BMI and note and between BMI and maximal oxygen consumption. No significant relationships have been found, however, between maximal oxygen consumption and note. Assessment of the importance of physical condition and therefore physical education in academic performance is of interest in order to implement the necessary hours of Physical Education. Furthermore, this subject should be characterised further in terms of its relation to the issue of health.
Źródło:
Journal of Physical Education & Health - Social Perspective; 2017, 6, 9; 19-25
2084-7971
Pojawia się w:
Journal of Physical Education & Health - Social Perspective
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Theoretical Analysis of Ballistic Electron Emission Microscopy: Band Structure Effects and Attenuation Lengths
Autorzy:
de Andres, P. L.
Reuter, K.
Garcia-Vidal, F. J.
Flores, F.
Hohenester, U.
Kocevar, P.
Powiązania:
https://bibliotekanauki.pl/articles/1968707.pdf
Data publikacji:
1998-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.Ch
72.10.Bg
73.20.At
Opis:
Using a quantum mechanical approach, we compute the ballistic electron emission microscopy current distribution in reciprocal space to compare experimental and theoretical spectroscopic I(V) curves. In the elastic limit, this formalism is a "parameter-free" representation of the problem. At low voltages, low temperatures, and for thin metallic layers, the elastic approximation is enough to explain the experiments (ballistic conditions). At low temperatures, inelastic effects can be taken into account approximately by introducing an effective electron-electron lifetime as an imaginary part in the energy. Ensemble Monte Carlo calculations were also performed to obtain ballistic electron emission microscopy currents in good agreement with the previous approach.
Źródło:
Acta Physica Polonica A; 1998, 93, 2; 281-287
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relativistic motion of classical charged particles in a uniform electromagnetic field
Autorzy:
Caltenco, J. H.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177930.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Frenet-Serret formulae
Helixs in Minkowski spacetime
Lorentz equation
Opis:
Here we show the importance of a systematic method to generate any integer power of a matrix in 2, 3 and 4 dimensions. This is motivated by the integration of Frenet–Serret formulae for the case of constant curvatures, and by the relativistic motion of a point charge into a homogeneous electromagnetic field, because in such situations it is necessary to calculate being a scalar. By these reasons, we believe that this work can be useful for people interested in linear algebra, differential geometry and electrodynamics.
Źródło:
World Scientific News; 2018, 97; 153-167
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Brans-Edgar-Ludwig equations for empty spacetimes
Autorzy:
Morales, J.
Ovando, G.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177881.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Bianchi identities
Brans-Edgar-Ludwig equations
Debever-Penrose principal directions
Null tetrad formalism
Petrov types
Opis:
We use the Newman-Penrose formalism to deduce the compatibility conditions for the Bianchi identities associated to vacuum spacetimes.
Źródło:
World Scientific News; 2018, 98; 199-205
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stirling numbers with negative indices
Autorzy:
Yaljá Montiel-Pérez, J.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177734.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Gould and Schläfli formulas
Stirling numbers
Opis:
We realize applications of expressions for Stirling numbers with negative indices, in particular, we show that the formulas of Zhi-Hong Sun are consequences of the known identities of Schläfli and Gould.
Źródło:
World Scientific News; 2018, 101; 217-221
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maxwell-Lorentz Matrix
Autorzy:
Montiel-Pérez, J. Yaljá
Pendleton, J.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177983.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Lorentz Group
Lorentz transformations
Maxwell equations
Opis:
Lorentz invariance of Maxwell electromagnetic equations is demonstrated in two complementary ways: first, we give a pedestrian review with three-vector equations, and we then express Maxwell equations in a four-vector matrix form (the Maxwell-Lorentz matrix) which demonstrates the intimate connection of Maxwell equations with the Lorentz group. Each Maxwell-Lorentz matrix component is the product of three matrices: a derivative matrix, a 4x4 Lorentz group generator matrix, and an electromagnetic field matrix. We obtain rotary Lorentz transformations of the electromagnetic field matrix from Lorentz equation matrices. We then transform the derivative and electromagnetic matrices and obtain an explicit matrix demonstration of Lorentz invariance of Maxwell equations. To obtain this result, we express all transformation matrices in exponential form to facilitate the application of simple Lorentz group algebra. The pedestrian approach illustrates what the Lorentz group matrix approach actually accomplishes and helps one to gain some appreciation of group theory methods.
Źródło:
World Scientific News; 2018, 96; 59-82
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Linearization of (second order operator)1/2
Autorzy:
López-Bonilla, J.
López-Vázquez, R.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1164128.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Cauchy-Riemann conditions
Laplacian operator
Pauli matrices
Weyl and Dirac equations
Opis:
We illustrate by means of the Pauli matrices how to linearize (second order operator)1/2 associated to the Weyl and Dirac equations. Besides, we exhibit the square root of the two dimensional Laplacian operator.
Źródło:
World Scientific News; 2018, 108; 224-228
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Todorov’s formula involving Stirling numbers of the second kind and Nörlund polynomials
Autorzy:
Zúñiga-Segundo, A.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1165650.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Bernoulli numbers
Duality property
Generalized chain rule of differentiation
Hoppe’s formula
Nörlund polynomials
Stirling numbers
Opis:
We use the Todorov’s formula for the generalized Bernoulli numbers, in terms of Stirling numbers of the second kind, to deduce the Guo-Qi and Schläfli identities. Our approach is based in the duality property between the Stirling numbers, and in the Nörlund polynomials. We also consider the Janjic’s definitions for the Stirling numbers.
Źródło:
World Scientific News; 2018, 107; 201-206
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Matrices and orthogonal polynomials
Autorzy:
López-Bonilla, J.
López-Vázquez, R.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177448.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Chebyshev
Hermite
Laguerre and Legendre polynomials
Lanczos algorithm
Leverrier-Takeno’s method
Three-member recurrence
Opis:
The Lanczos algorithm of minimized iterations shows that a polynomial verifying a three-term recurrence relation can be written as the determinant of a tridiagonal matrix, here we exhibit examples of this property. Besides, for several orthogonal polynomials, Cohen proved that their roots are the proper values of symmetric tridiagonal matrices; here we give examples of this Cohen’s result for the Legendre, Laguerre, and Hermite polynomials, which are important in applications to numerical analysis and quantum mechanics.
Źródło:
World Scientific News; 2018, 103; 234-241
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An alternative to Gower’s inverse matrix
Autorzy:
López-Bonilla, J.
López-Vázquez, R.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177483.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Adjoint matrix
Characteristic equation
Eigenvalue problem
Faddeev-Sominsky’s method
Gower’s pseudoinverse matrix
Leverrier-Takeno’s algorithm
Opis:
We show that the Faddeev-Sominsky’s process allows construct a natural inverse for any square matrix, which is an alternative to the inverse obtained by Gower.
Źródło:
World Scientific News; 2018, 102; 166-172
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Faddeev-Sominsky’s algorithm
Autorzy:
Torres-Silva, H.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1166341.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Adjoint matrix
Characteristic equation
Eigenvalue problem
Faddeev-Sominsky’s method
Inverse matrix
Leverrier-Takeno’s algorithm
Resolvent of a matrix
Opis:
We comment that the Faddeev-Sominsky’s process to obtain an inverse matrix is equivalent to the Cayley-Hamilton-Frobenius theorem plus the Leverrier-Takeno’s method to construct the characteristic polynomial of an arbitrary matrix. Besides, we deduce the Lanczos expression for the resolvent of the corresponding matrix.
Źródło:
World Scientific News; 2018, 106; 238-244
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Moore-Penrose’s inverse and solutions of linear systems
Autorzy:
López-Bonilla, J.
López-Vázquez, R.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177742.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Least squares technique
Linear systems
Pseudoinverse of Moore-Penrose
SVD
Opis:
We employ the generalized inverse matrix of Moore-Penrose to study the existence and uniqueness of the solutions for over- and under-determined linear systems, in harmony with the least squares method.
Źródło:
World Scientific News; 2018, 101; 246-252
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On eigenvectors associated to a multiple eigenvalue
Autorzy:
Cruz-Santiago, R.
López-Bonilla, J.
Vidal-Beltrán, S.
Powiązania:
https://bibliotekanauki.pl/articles/1177790.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Eigenvalue problem
Faddeev-Sominsky’s technique
Gower’s method
Opis:
If all roots of the characteristic polynomial of a matrix have distinct values, then the Faddeev-Sominsky’s algorithm gives the corresponding eigenvectors. Here we exhibit the method of Gower to construct the proper vectors associated to a multiple eigenvalue.
Źródło:
World Scientific News; 2018, 100; 248-253
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the friction coefficients of chestnut (Castanea sativa Mill.) sawn timber
Autorzy:
Villar-Garcia, J.R.
Vidal-Lopez, P.
Corbacho, A.J.
Moya, M.
Powiązania:
https://bibliotekanauki.pl/articles/2082657.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
wood
mechanical properties
friction coefficient
direct shear test
Opis:
This work provides the values of both the static and the kinetic friction coefficients for chestnut (Castanea sativa Mill.) of Spanish origin. Knowledge concerning these coefficients has its main application in the study of agroindustrial structures and machinery with timber members in contact. This determination was developed taking into account the timber anisotropy to establish surfaces and directions of slipping. A modified direct shear test device was used to conduct the tests and reproduce the tribological system. This procedure was functional and reliable and considered suitable for standardizing the friction measurement between timber surfaces, since this device is widely distributed in geotechnical and materials laboratories and the European codes do not specify a procedure or device to carry it out. The average values obtained were 0.46 for the static coefficient and 0.33 for the kinetic one, without considering the surfaces and directions of slipping. These values ranged between 0.36 and 0.55 for the static friction coefficient and between 0.28 and 0.39 for the kinetic friction coefficient depending on the direction considered and also taking into account the anisotropy of the timber. A good correlation was obtained between both coefficients, thus allowing for the estimation of the kinetic coefficient from the static one.
Źródło:
International Agrophysics; 2020, 34, 1; 65-77
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł

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