Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 6

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
Elastic reverse-time migration (RTM) can reflect the underground elastic information more comprehensively than single-component Pwave migration. One of the most important requirements of elastic RTM is to solve wave equations. The imaging accuracy and efficiency of RTM depends heavily on the algorithms used for solving wave equations. In this paper, we propose an efficient staggered-grid finite-difference (SFD) scheme based on a sampling approximation method with adaptive variable difference operator lengths to implement elastic prestack RTM. Numerical dispersion analysis and wavefield extrapolation results show that the sampling approximation SFD scheme has greater accuracy than the conventional Taylor-series expansion SFD scheme. We also test the elastic RTM algorithm on theoretical models and a field data set, respectively. Experiments presented demonstrate that elastic RTM using the proposed SFD scheme can generate better images than that using the Taylor-series expansion SFD scheme, particularly for PS images. Furthermore, the application of adaptive variable difference operator lengths can effectively improve the computational efficiency of elastic RTM.
EN
First principles calculations have been performed to investigate the structure, electronic and optical properties of Y3Fe5O12. Both the cubic and trigonal phases have been considered in our calculation. The calculated structural parameters are slightly larger than the experimental values. The band structures show that Y3Fe5O12 in cubic and trigonal phases have direct band gaps of 0.65 and 0.17 eV. The calculations of dielectric function, absorption, extinction coefficient, refractive index, energy loss function and reflectivity are presented.
3
Content available remote Central-symmetrical property analysis on circularly orthogonal moments
EN
In this research, we have proposed the central-symmetrical property of image reconstructions from Zernike moments and pseudo-Zernike moments. We conducted the image reconstructions from the odd, even, and complete sets of Zernike moments and pseudo-Zernike moments, and verified the proposed central-symmetrical property. We have concluded that if the original image is centrally symmetrical, the image reconstructions from even order sets are identical to those from the corresponding complete order sets of either Zernike or pseudo-Zernike moments.
EN
The Level-2 monthly GRACE gravity field models issued by Center for Space Research (CSR), GeoForschungs Zentrum (GFZ), and Jet Propulsion Laboratory (JPL) are treated as observations used to extract the equivalent water height (EWH) with the robust independent component analysis (RICA). The smoothing radii of 300, 400, and 500 km are tested, respectively, in the Gaussian smoothing kernel function to reduce the observation Gaussianity. Three independent components are obtained by RICA in the spatial domain; the first component matches the geophysical signal, and the other two match the north-south strip and the other noises. The first mode is used to estimate EWHs of CSR, JPL, and GFZ, and compared with the classical empirical decorrelation method (EDM). The EWH STDs for 12 months in 2010 extracted by RICA and EDM show the obvious fluctuation. The results indicate that the sharp EWH changes in some areas have an important global effect, like in Amazon, Mekong, and Zambezi basins.
EN
To ensure safe and reliable battery operations, an accurate battery state of charge (SOC) estimation is critical for the battery systems used in electric vehicles and hybrid electric vehicles because of the arduous operation conditions. This paper presents a SOC estimator designed based on the unscented Kalman filter (UKF), which is very popular in the state estimation in non-linear systems. The dynamic characteristics of the battery are modeled with an equivalent circuit, which is composed of two capacitors, three resistors and a voltage source to simulate the equilibrium open circuit voltage (OCV). To relieve the computation requirement of the original UKF, an efficient implementation using a Cholesky factorization is investigated, and thereby a SR-UKF based SOC estimator is proposed. Experiment results shows that the model proposed can track the dynamic behavior of the battery very well and the UKF-based SOC estimator has a good performance in the state estimation, and a comparison with EKFbased estimator also shows that a better accuracy can be got by the proposed UKF- based estimator.
PL
Artykuł prezentuje system kontroli SOC (state of charge – stan naładowania) baterii używanych w pojazdach elektrycznych. System bazuje na filtrze Kalmana typu UKF. Własności dynamiczne baterii modelowane są przy pomocy odpowiedniego obwodu elektrycznego zastępczego. System może śledzić właściwości dynamiczne baterii i badać jej stan naładowania.
EN
Along with the expansion of the mining capacity, the mine gas accident is more and more. There are still many shortages and defects in gas monitoring system in the previous gas concentration monitoring method. Therefore, we propose the optical fiber sensing technology of mine gas method based on Extrinsic Fabry-Perot Interferometer (EFPI) technology. According to the analysis of interference spectrum from EFPI fiber optic sensor, the varying information is obtained. Then the concentration of the gas is calculated, by Beer Law and the relations between light intensity and concentration of gas. The method implements the high resolution of optical fiber sensing, and avoids the light interference and so on. This method, which can eliminate all kinds of interference in monitoring gas concentration, is a new method on measuring the concentration of gas at harsh environments under coal mine. It has extremely high security and strong anti-interference capability. The method works well in inflammable and explosive environment, which has an important significance for safety production in the coal.
PL
Wraz z rozwojem górnictwa w górnictwie występuje coraz więcej wypadków. Obserwuje się wciąż brak lub wadliwe działanie systemów monitorujących zawartość gazów w kopalniach. Dlatego autorzy niniejszej pracy zaproponowali technologię wykrywania obecności gazów przy pomocy specjalnych włókien przy pomocy interferometru Fabry-Perot'a EFPI. Koncentrację gazów oblicza się przy pomocy prawa Beer'a, z zależności pomiędzy intensywnością światła w czujniku optycznym, a stężeniem gazu. Metoda ta pozwala na wdrożenie do górnictwa metod wykrywania gazów przy wykorzystaniu włókien optycznych, wykluczając jednocześnie zjawisko interferencji świetlnej i temu podobnych. Metoda ta, eliminuje wszelkiego rodzaju interferencję w monitorowaniu stężenia gazów jest nowatorską metodą pomiaru stężenia gazów w kopalniach podziemnych. Metoda ta również zapewnia bezpieczeństwo. Metoda ta sprawdza się zarówno w środowisku gdzie nie ma zagrożenia gazowego, jak również w środowisku gdzie mogą wystąpić gazy wybuchowe, co jest bardzo ważne dla zapewnienia bezpieczeństwa pracy przy produkcji węgla.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.