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Wyszukujesz frazę "Li, P. J." wg kryterium: Autor


Wyświetlanie 1-8 z 8
Tytuł:
Design of LED collimator for uniform illumination using two freeform lenses
Autorzy:
Zeng, J.
Li, X.
Ge, P.
Powiązania:
https://bibliotekanauki.pl/articles/173429.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
illumination design
lenses
light-emitting diodes
optical design
high uniformity
Opis:
Regulating the illuminance distribution of an LED collimator to produce a uniform illumination in both the near field and the far field is a challenge in illumination design. In this paper, we present an effective method for designing two separated freeform lenses to control the illuminance distribution and the direction of the rays from the LED. The first lens redistributes the ray energy, and the second one collimates them to obtain a uniform collimated illumination. According to the conservation law of energy, Snell’s law, Fermat’s law and tangent-plane iterative method, the two freeform surfaces could be calculated simultaneously. The simulation results show that the two freeform lenses can control most of rays into an angle within ±1.5° for an LED with 1 × 1 mm size. The illuminance uniformities are higher than 0.9 in both the near field and the far field.
Źródło:
Optica Applicata; 2018, 48, 3; 413-420
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sensitive detection of acetylene by second derivative spectra with tunable diode laser absorption spectroscopy
Autorzy:
Deng, H.
Sun, J.
Li, P.
Liu, Y.
Yu, B.
Li, J.
Powiązania:
https://bibliotekanauki.pl/articles/174963.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
tunable diode laser absorption spectroscopy
TDLAS
signal processing
Savitzky–Golay filter
trace gas detection
Opis:
A tunable diode laser absorption spectrometer was developed for trace acetylene gas analysis, the system performance was evaluated by combing an appropriate digital signal processing methods, i.e., Savitzky–Golay smoothing and differentiation algorithm. The calculation of the derivative spectra by this method is accompanied by simultaneous data smoothing. Based on the 2nd deriv- ative spectra detection method, the Allan variance technique indicates a C2H2 detection limit of 1.7ppm for 1-s averaging time, and a minimum noise level of 62ppb (parts per billion), at the optimum integration time of ~60s. The calculated 2nd derivative spectra with better resolution, lower detection limits, save signal processing time, and improve the ability to distinguish unresolved spectral signals.
Źródło:
Optica Applicata; 2016, 46, 3; 353-363
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic evolution of mixed circular edge-screw dislocations
Autorzy:
Gao, P.
Li, J.
Cheng, K.
Duan, M.
Powiązania:
https://bibliotekanauki.pl/articles/173359.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
mixed circular edge-screw dislocations
optical vortex
circular edge dislocations
atmospheric turbulence
Opis:
Based on the extended Huygens–Fresnel principle, the analytical expressions for the cross-spectral density function of mixed circular edge-screw dislocations beams propagating through atmospheric turbulence have been derived, and used to study the dynamic evolution of mixed circular edge-screw dislocations in free space and atmospheric turbulence. It is shown that the radius of circular edge dislocations increases with increasing propagation distance, and both the positions of the optical vortex and the center of circular edge dislocations are located at the point (0, 0) when mixed circular edge-screw dislocations propagate in free space. When mixed circular edge-screw dislocations propagate in the atmospheric turbulence, the position of optical vortices varies with increasing propagation distance, the circular edge dislocation evolves into a pair of optical vortices with the opposite topological charge ±1, and the pair of optical vortices will annihilate as soon as the propagation distance becomes large enough.
Źródło:
Optica Applicata; 2017, 47, 3; 471-481
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An innovative methodology for recycling iron from magnetic preconcentrate of an iron ore tailing
Autorzy:
Yu, J.
Han, Y.
Gao, P.
Li, Y.
Yuan, S.
Li, W.
Powiązania:
https://bibliotekanauki.pl/articles/110888.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
magnetic preconcentrate
iron ore tailing
iron recycling
fluidized magnetization roasting
magnetic separation
Opis:
Iron ore tailing is a kind of hazardous solid waste produced by iron and steel industry. In order to separate and recycle iron from the magnetic preconcentrate of an iron ore tailing, an innovative technological route of fluidized magnetization roasting followed by low-intensity magnetic separation was proposed in this paper. The effects of roasting temperature, dosages of reducing gas CO and fluidizing gas N2 on recovery rate of iron were carried out and optimized. The results showed that the hematite was almost reduced to magnetite by a gas mixture of 4 m3/h CO and 1 m3/h N2 at roasting temperature of 540 °C. Under the optimized conditions, a magnetic concentrate assaying 61.4 wt% Fe with a recovery rate of 81.8% was obtained from the magnetic preconcentrate of an iron ore tailing. The iron chemical phase, X-ray diffraction (XRD), and optical metallographic microscope analyses revealed that siderite was converted to magnetite successfully after roasting, and some coarse magnetite-hematite interlocking particles were formed due to insufficient reaction time, which could also be recovered by magnetic separation after liberating from gangue minerals.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 668-676
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A polarization filter at 1550 nm based on photonic crystal fiber with symmetry around gold-coated holes
Autorzy:
Zha, F.
Li, J.
Sun, P.
Wang, X.
Powiązania:
https://bibliotekanauki.pl/articles/173897.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
photonic crystal fiber
polarization filter
finite element method
surface plasmon resonance
Opis:
A polarization photonic crystal fiber based on surface plasmon resonance is proposed in this paper. The photonic crystal fiber with gold coated holes is studied through using the finite element method. The impacts of structural parameters on the resonance characteristics are discussed. Numerical simulations show that the resonance wavelength can be modulated by changing the parameters of the air holes and thickness of gold layer. At the resonance wavelength 1550 nm, the loss is 3.8045 dB/m in x-polarization and the loss is 28464 dB/m in y-polarization by adjusting the size of the gold-coated holes and the place of air holes. Results show that the loss of y-polarized mode is much larger than the loss of x-polarized mode. The y-polarized mode is suppressed, and only x-polarized mode can be guided at the resonance wavelength of y-polarized mode. The results indicate that the mode polarized in one direction can be filtered out selectively by adjusting the diameter of air holes, and the filtering effect in a communication band is achieved.
Źródło:
Optica Applicata; 2018, 48, 4; 609-620
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of root canal irrigation adopting innovative needles with dimple and protrusion
Autorzy:
Li, P.
Zhang, D.
Xie, Y.
Lan, J.
Powiązania:
https://bibliotekanauki.pl/articles/307257.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dimple
protrusion
innovative needles
numerical simulation
passive flow control methods
root canal irrigation
wychylenie zębów
symulacja komputerowa
kanał zębowy
Opis:
As important passive flow control methods, dimples and protrusions have been successfully implemented via geometric modifications to manipulate flow fields to get a desired flow parameters enhancement. In this research, two novel needles were proposed based on a prototype by means of the dimple and protrusion, and flow patterns within a root canal during final irrigation with these needles were numerically investigated. The calculation cases consistent with the clinically realistic irrigant flow rates, which are 0.02, 0.16 and 0.26 mL s–1 are marked as case A, B and C, respectively. The characteristic parameters to estimate irrigation efficiency, such as shearing effect, mean apical pressure, irrigation replacement and fluid agitation, were compared and the optimal geometry in every calculation case was obtained. As shown from the results, flow rates and needle geometries were the causes of irrigation parameters variations. The sum of shear stress, irrigation replacement and fluid agitation were equal in the low flow rate case A, however, the needle with a protrusion on its tip had advantages in the three irrigation characteristic parameters above in calculation case B, and the needle with a dimple on its tip had advantages in calculation case C. Furthermore, the needles proposed did not give rise to the risk of irrigant extrusion. These needles can be better choices at larger flow rates. Therefore, needle geometry optimizations utilizing passive flow control methods are worthy to be investigated in the root canal irrigation enhancement.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 1; 43-50
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of calcination temperature on activation behaviors of coal-series kaolin by fluidized bed calcination
Autorzy:
Yuan, S.
Han, Y.
Li, Y.
Gao, P.
Yu, J.
Powiązania:
https://bibliotekanauki.pl/articles/109800.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
coal-series kaolin
fluidized bed calcination
calcination temperature
activation behaviors
Opis:
This paper is aimed at investigating activation behaviors for coal-series kaolin using fluidized bed calcination as a novel method. The properties of calcined products at different temperature by fluidized bed calcination were evaluated by determination of weight loss rate, whiteness, chemical oxygen demand (COD), aluminum dissolution degree. The thermal behaviors and reaction mechanism were characterized by thermo gravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), particle size distribution (PSD) and scanning electron microscopy (SEM). The results showed that calcination temperature was essential factor determining the properties and crystallinity of calcined products using fluidized bed calcination. Coal-series kaolin transformed into irregular and amorphous metakaolin with excellent properties as calcined at 600-900 °C, which attributed to the dehydroxylation of kaolinite and combustion of carbon/organic matter. Calcined kaolin eliminated activity ascribed to the recrystallization into mullite when calcination temperature was over 1000 °C. It was believed that fluidized bed calcination was an efficient thermal activation technology for coal-series kaolin and the calcination temperature should be controlled accurately.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 2; 590-600
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical analysis of a hollow laser beam transmitting in an off-axis Cassegrain optical antenna system
Autorzy:
Mi, C
Jiang, P
Yang, H.
Ke, S
Li, B
Liu, J.
Powiązania:
https://bibliotekanauki.pl/articles/174358.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Cassegrain optical antenna
off-axis hollow laser beam
receiving efficiency
Opis:
The optical model of a Cassegrain optical antenna with a confocal double-parabolic reflector structure has been designed, and the propagation characteristics of a hollow laser beam, which could avoid the loss of energy caused by the subreflector center reflection in the optical antenna, has been researched in this paper. By detailed analysis and numerical calculations of a receiving Cassegrain antenna with different deflection angles, the coupling efficiency curve and 3-D distributions of the receiving light intensity for different inclined angles have been obtained.
Źródło:
Optica Applicata; 2014, 44, 3; 421-431
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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