Autor: Torres, J. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Evaluation of Guitars and Violins Made using Alternative Woods through Mobility Measurements
Autorzy:: Torres, J. A.
Torres-Martínez, R.
Powiązania:: https://bibliotekanauki.pl/articles/176571.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: mobility
violin
guitar
luthier
Stradivari
Opis:: The feasibility of substituting the types of wood usually employed in the making of guitars and violins was analyzed, but without comparing the properties of involved materials as it is often reported; in this work, the vibrational behavior of twelve guitars and three violins built with alternative types of woods was compared to data of classical instruments available in the literature. In the guitars here measured, the back plate and ribs were not made from traditional woods; while in the violins, only the top plate was made from an alternative type of wood. The results showed that changing the wood of back plate and ribs does not radically affect the typical mobility of a guitar; however, the expected mobility for a violin was not clearly obtained substituting the wood of the top plate. Thus it seems feasible to substitute the wood of back plate and ribs in guitars without causing dramatic changes in their performance; in contrast, a change of the wood type for top plate in violins seems inadvisable unless the design of the top plate is modified to compensate the differences between the woods.
Źródło:: Archives of Acoustics; 2015, 40, 3; 351-358
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Soil wind erosion characterization in south-eastern Spain using traditional methods in front of an innovative type of dust collector
Autorzy:: Guerrero, R.
Valenzuela, J.L.
Torres, J.L.
Lozano, J.
Asensio, C.
Powiązania:: https://bibliotekanauki.pl/articles/2082948.pdf
Data publikacji:: 2020
Wydawca:: Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:: dust collector
semi-arid environment
tilled
soil
unploughed soil
wind tunnel
Opis:: The movement of soil particles by the wind can be measured using wind tunnels and collectors, or dust traps. We tested both in Southeast Spain in order to compare movement in four types of soil. Our tests were carried out in a well-tilled orchard on an Anthrosol, an unploughed Leptosol and Arenosol, and finally on an olive-cropped Cambisol. We estimated soil loss using a wind tunnel with a built-in laser-scanner, and then compared the results with records from nine vaned masts, each with four big spring number eight collectors at different heights, and the same for another nine masts but with a new type of dust trap known as the multidirectional. The collectors can differentiate between overall loss and particle deposition, which is not detectable on a larger scale in the tunnel. The results from the big spring number eight traps and our wind tunnel showed a high degree of correlation (R² = 0.933) and an even closer correlation with the multidirectional trap (R² = 0.978). Moreover, the new multidirectional trap collectors are very efficient and easy to manufacture from thermoplastic filaments with an industrial 3D printer.
Źródło:: International Agrophysics; 2020, 34, 4; 503-510
0236-8722
Pojawia się w:: International Agrophysics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Plasma Oscillations in Nanotransistors: Application to THz Radiations Detection and Generation
Autorzy:: Marinchio, H.
Sabatini, G.
Palermo, C.
Nouvel, P.
Torres, J.
Varani, L.
Shiktorov, P.
Starikov, E.
Gružinskis, V.
Powiązania:: https://bibliotekanauki.pl/articles/1505457.pdf
Data publikacji:: 2011-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 72.15.Nj
72.20.Ht
72.30.+q
Opis:: By means of a numerical hydrodynamic model, we consider the mechanism of collective plasma oscillations in a field-effect transistor channel under different excitations and biasing conditions. First, we consider the case of a device externally-excited by a harmonic optical beating or an electronic excitation under constant current condition at the drain. Both situations exhibit sharp resonances related to the first odd plasma modes illustrating the possibility of using the HEMT as a terahertz photomixer or detector. Then, we demonstrate that the frequencies, amplitudes and quality factors of the resonances can be strongly modified by varying the drain biasing condition from current- to voltage-driven operation.
Źródło:: Acta Physica Polonica A; 2011, 119, 2; 103-106
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: THz Emission Induced by an Optical Beating in Nanometer-Length High-Electron-Mobility Transistors
Autorzy:: Nouvel, P.
Torres, J.
Marinchio, H.
Laurent, T.
Palermo, C.
Varani, L.
Teppe, F.
Shiktorov, P.
Starikov, E.
Gruzinskis, V.
Powiązania:: https://bibliotekanauki.pl/articles/1505652.pdf
Data publikacji:: 2011-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 72.15.Nj
72.20.Ht
72.30.+q
Opis:: Experimental results of direct measurement of resonant terahertz emission optically excited in InGaAs HEMT channels are presented. The emission was attributed to two-dimensional plasma waves excited by photogeneration of electron-hole pairs in the HEMT channel at the frequency of the beating of two cw-laser sources. The presence of resonances for the radiation emission in the range of $f_0$ ± 10 GHz (with $f_0$ from 0.3 up to 0.5 THz) detected by a Si-bolometer is found. The intensity of THz emission exhibits a nonlinear growth with increase of the pumping power.
Źródło:: Acta Physica Polonica A; 2011, 119, 2; 199-202
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Small-Signal Characterization of FET/HEMT for Terahertz Applications
Autorzy:: Starikov, E.
Shiktorov, P.
Gružinskis, V.
Marinchio, H.
Nouvel, P.
Torres, J.
Palermo, C.
Chusseau, L.
Varani, L.
Ziadé, P.
Powiązania:: https://bibliotekanauki.pl/articles/1505675.pdf
Data publikacji:: 2011-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 72.20.Ht
72.30.+q
Opis:: Calculations of the small-signal response of InGaAs HEMTs by using the hydrodynamic approach coupled with a pseudo-2D Poisson equation are performed. The spectra of small-signal admittance and impedance are found to demonstrate series of the resonant peaks corresponding to excitation of plasma waves. Possibilities and conditions of instability onset and THz signal detection are discussed.
Źródło:: Acta Physica Polonica A; 2011, 119, 2; 203-205
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Measurement of Pulsed Current-Voltage Characteristics of AlGaN/GaN HEMTs from Room Temperature to~15~K
Autorzy:: Laurent, T.
Sharma, R.
Torres, J.
Nouvel, P.
Blin, S.
Palermo, C.
Varani, L.
Cordier, Y.
Chmielowska, M.
Faurie,, J.
Beaumont, B.
Powiązania:: https://bibliotekanauki.pl/articles/1505650.pdf
Data publikacji:: 2011-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 72.80.Ey
73.21.Fg
73.40.-c
Opis:: We report measurements of the pulsed and dc current-voltage characteristics of AlGaN/GaN high-electron-mobility transistors as functions of geometry, temperature (from 300 down to 15 K), and operating conditions. An increase in the drain current with shortening of the pulse width from 1 μs to 400 ns is found to be significant at room temperature whilst this behavior is inverted or even removed at 77 and 15 K temperatures.
Źródło:: Acta Physica Polonica A; 2011, 119, 2; 196-198
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: An Experimental Approach to Vibro-Acoustic Study of Beam-Type Structures
Autorzy:: Torres-Romero, J.
Cardenas, W.
Carbajo, J.
Segovia Eulogio, E. G.
Ramis-Soriano, J.
Powiązania:: https://bibliotekanauki.pl/articles/178014.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: beam
modal shape
modal analysis
MLS
Maximum Length Sequence
bending wave propagation velocity
Opis:: In this paper an alternative procedure to vibro-acoustics study of beam-type structures is presented. With this procedure, it is possible to determine the resonant modes, the bending wave propagation velocity through the study of the radiated acoustic field and their temporal evolution in the frequency range selected. As regards the purely experimental aspect, it is worth noting that the exciter device is an actuator similar to is the one employed in distributed modes loudspeakers; the test signal used is a pseudo random sequence, in particular, an MLS (Maximum Length Sequence), facilitates post processing. The study case was applied to two beam-type structures made of a sandstone material called Bateig. The experimental results of the modal response and the bending propagation velocity are compared with well-established analytical solution: Euler-Bernoulli and Timoshenko models, and numerical models: Finite Element Method – FEM, showing a good agreement.
Źródło:: Archives of Acoustics; 2018, 43, 2; 283-295
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Terahertz Detection of Quantum Cascade Laser Emission by Plasma Waves in Field Effect Transistors
Autorzy:: Teppe, F.
Consejo, C.
Torres, J.
Chenaud, B.
Solignac, P.
Fathololoumi, S.
Wasilewski, Z.
Zholudev, M.
Dyakonova, N.
Coquillat, D.
El Fatimy, A.
Buzatu, P.
Chaubet, C.
Knap, W.
Powiązania:: https://bibliotekanauki.pl/articles/1492959.pdf
Data publikacji:: 2011-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 85.30.Tv
07.57.Kp
52.35.-g
Opis:: We report on the resonant detection of a 3.1 THz radiation produced by a quantum cascade laser using a 250 nm gate length GaAs/AlGaAs field effect transistor at liquid nitrogen temperature. We show that the physical mechanism of the detection is related to the plasma waves excited in the transistor channel. The detection is enhanced by increasing the drain current and driving the transistor into saturation regime. These results clearly show that plasma wave nanometer-size transistors can be used as detectors in all-solid-state terahertz systems where quantum cascade lasers act as sources.
Źródło:: Acta Physica Polonica A; 2011, 120, 5; 930-932
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Voltage Controlled Terahertz Transmission Enhancement through GaN Quantum Wells
Autorzy:: Laurent, T.
Sharma, R.
Torres, J.
Nouvel, P.
Blin, S.
Chusseau, L.
Palermo, C.
Varani, L.
Cordier, Y.
Chmielowska, M.
Faurie, J.
Beaumont, B.
Shiktorov, P.
Starikov, E.
Gruzinskis, V.
Powiązania:: https://bibliotekanauki.pl/articles/1505459.pdf
Data publikacji:: 2011-02
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 78.20.-e
78.67.De
73.21.Fg
Opis:: We report transmission measurements of GaN quantum well grown on sapphire substrate in the 220-325 GHz frequency band at low temperatures. A significant enhancement of the transmitted beam intensity with the applied voltage on the devices under test is found.
Źródło:: Acta Physica Polonica A; 2011, 119, 2; 107-110
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Two-dimensional Newtons problem of minimal resistance
Autorzy:: Silva, C. J.
Torres, D. F.
Powiązania:: https://bibliotekanauki.pl/articles/969988.pdf
Data publikacji:: 2006
Wydawca:: Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:: Newton's problem of minimal resistance
dimension two
calculus of variations
optimal control
Opis:: Newton's problem of minimal resistance is one of the first problems of optimal control: it was proposed, and its solution given, by Isaac Newton in his masterful Principia Mathematica, in 1686. The problem consists of determining, in dimension three, the shape of an axis-symmetric body, with assigned radius and height, which offers minimum resistance when it is moving in a resistant medium. The problem has a very rich history and is well documented in the literature. Of course, at a first glance, one suspects that the two dimensional case should be well known. Nevertheless, we have looked into numerous references and asked at least as many experts on the problem, and we have not been able to identify a single source. Solution was always plausible to everyone who thought about the problem, and writing it down was always thought not to be worthwhile. Here we show that this is not the case: the two-dimensional problem is richer than the classical one, being, in some sense, more interesting. Novelties include: (i) while in the classical three-dimensional problem only the restricted case makes sense (without restriction on the monotonicity of admissible functions the problem does not admit a local minimum), we prove that in dimension two the unrestricted problem is also well-posed when the ratio of height versus radius of base is greater than a given quantity; (ii) while in three dimensions the (restricted) problem has a unique solution, we show that in the restricted two-dimensional problem the minimizer is not always unique - when the height of the body is less or equal than its base radius, there exists infinitely many minimizing functions.
Źródło:: Control and Cybernetics; 2006, 35, 4; 965-975
0324-8569
Pojawia się w:: Control and Cybernetics
Dostawca treści:: Biblioteka Nauki

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