Wyniki wyszukiwania - Biblioteka Nauki

1

Szkła i światłowody aktywne jako luminescencyjne źródła promieniowania

100%

Dorosz D. , Kochanowicz M. , Żmojda J. , Mazerski W. , Miluski P. , Dorosz J.

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2012

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tom T. 64, nr 2

172-176

PL

W artykule przedstawiono wyniki badań nad dwoma układami szkieł: fluorokrzemianowego i fluorofosforanowego, domieszkowanych jednocześnie jonami Nd3+ i Yb3+. Przeprowadzono optymalizację zawartości domieszek w celu przestrzennego dopasowania przekrojów czynnych na emisję donora (Nd3+) i absorpcję akceptora (Yb3+). W wyniku pobudzania układów diodą laserową o długości fali 808 nm uzyskano szerokie widmo luminescencji w okolicach 1 µm będące superpozycją przejść 4F3/2--4I11/2 dla Nd3+ i 2F5/2--2F7/2 dla Yb3+. Z opracowanych szkieł charakteryzujących się najszerszym widmem luminescencji wytworzono światłowody, uzyskując wzmocnioną emisję spontaniczną (ASE) na długości fali 1,1 µm.

EN

In the paper, spectroscopic properties of fluorosilicate and fluorophosphate glass systems co-doped with Nd3+/Yb3+ ions were investigated. The optimization of the molar concentration of dopants was determined with respect to the spectral overlaps of the emission cross-section of neodymium ions and the absorption cross-section of ytterbium ions. As a result of the optical excitation with a laser diode at a wavelength of 808 nm, the strong and wide emission was observed corresponding to a superposition of optical transitions 4F3/2 -- 4I11/2 (Nd3+) and 2F5/2 -- 2F7/2(Yb3+). The optimization of Nd3+/Yb3+transfer in both glasses allowed us to fabricate optical fibres that showed narrowing and red-shifting of the amplified spontaneous emission (ASE) at 1.1 µm.

2

Synthesis and Characterization of an Efficient New Liquid Laser Dye Material - Chalcone (DMAPPP)

99%

Elzupir A. , Ibnaouf K. , Idriss H. , Ibrahem M. , Prasad S. , Alrajhi M. , AlSalhi M. , Alaamer A.

Acta Physica Polonica A

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2018

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tom 133

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nr 1

121-125

EN

This paper comprises the synthesis and characterization of 3-(4-(dimethylamino)phenyl)-1-phenyl-(2E)-propen-1-one (DMAPPP) and its application as a new laser medium. The absorption and fluorescence spectra of DMAPPP under different solvents and concentrations have been investigated. The amplified spontaneous emission performance of DMAPPP under various concentrations, organic solvents and pump pulse energies of Nd:YAG laser (355 nm) was also studied. The amplified spontaneous emission spectra of DMAPPP in solution were compared with a conventional laser dye of coumarin 503, under the same identical conditions. The gain and the fluorescence quantum yield of DMAPPP were determined. The most important features are: (1) DMAPPP has an excellent photochemical stability, (2) the amplified spontaneous emission from the DMAPPP was tuned in the wavelength region between 515 and 548 nm. This could be the first detailed paper on laser properties of DMAPPP.

3

Decreasing the threshold current density in Si lasers fabricated by using dressed-photons

85%

Tanaka H. , Kawazoe T. , Ohtsu M. , Akahane K.

Fluorescent Materials

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2015

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tom 1

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nr 1

EN

We fabricated a silicon (Si) laser by applying a dressed-photon–phonon assisted annealing process to a ridge-type light waveguide that we fabricated via siliconon- insulator (SOI) technology. We also evaluated a nearinfrared Si photodiode having optical gain to estimate the differential gain coefficient for designing lightwaveguides. We designed light waveguides having a thickness of 15 μm to realize a large optical confinement factor. The fabricated Si laser oscillated at a wavelength of 1.4 μm. The intensity of amplified spontaneous emission (ASE) lightwas too low to be observed, because the threshold current density was so low that the Si laser started oscillating immediately after ASE occurred. The threshold current density for oscillation was estimated to be 40 A/cm2 from the current– voltage characteristic. This threshold current density was twenty-eight times smaller than that of a Si laser we fabricated previously.

4

Effect of sample-preparation methods on the quantification of selected flavonoids in plant materials by high performance liquid chromatography

71%

Waksmundzka-Hajnos M. , Wianowska D. , Oniszczuk A. , Dawidowicz A. L.

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2008

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tom Vol. 20, no. 3

475-488

EN

Extraction yield of flavonoids from plant material Sambucus nigra L. inflorescence and Polygonum aviculare herb was determined by use of various methods of liquid-solid extraction - Soxhlet extraction, ultrasonification (USAE), microwave-assisted extraction (MASE), and accelerated solvent extraction (ASE). Methanol was used as extractant. Crude extracts were evaporated to dryness and prepared to achieve fractionation of flavonoids by LLE or SPE. Samples containing the flavonoid fraction were analysed by RP-HPLC. For quantitative purposes the external standard method with a calibration plot for every standard was used. It was found that yield depends first of all on the plant material from which flavonoid fraction was extracted. For Sambucus nigra L. inflorescence the most effective method was exhaustive extraction in a Soxhlet apparatus. For Polygonum aviculare the most effective method was ASE. The best purification method was SPE on C 18adsorbent, which resulted in the highest recoveries and repeatabilities.

5

Approximate dynamic programming in robust tracking control of wheeled mobile robot

57%

Hendzel Z. , Szuster M.

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2009

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tom Vol. LVI, nr 3

223-236

EN

In this work, a novel approach to designing an on-line tracking controller for a nonholonomic wheeled mobile robot (WMR) is presented. The controller consists of nonlinear neural feedback compensator, PD control law and supervisory element, which assure stability of the system. Neural network for feedback compensation is learned through approximate dynamic programming (ADP). To obtain stability in the learning phase and robustness in face of disturbances, an additional control signal derived from Lyapunov stability theorem based on the variable structure systems theory is provided. Verification of the proposed control algorithm was realized on a wheeled mobile robot Pioneer-2DX, and confirmed the assumed behavior of the control system.

PL

W pracy przedstawiono nowe ujęcie problematyki sterowania nadążnego mobilnym robotem dwukołowym. Algorytm bazuje na metodzie uczenia ze wzmocnieniem o strukturze aktor-krytyk i nie wymaga uczenia wstępnego, działa on-line bez znajomości modelu robota. Element generujący sterowania (aktor - ASE) oraz element generujący sygnał wewnętrznego wzmocnienia (krytyk - ACE) są zrealizowane w postaci sztucznej sieci neuronowej (SN). Prezentowany algorytm sterowania zweryfikowano na rzeczywistym obiekcie, dwukołowym robocie mobilnym Pioneer-2DX. Badania potwierdziły poprawność przyjętego rozwiązania.