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EN
Seismic waves propagating through viscoelastic media experience stratigraphic absorption and attenuation effects, which directly affect the imaging resolution in seismic exploration. Without stratigraphic absorption, the ratio of deep reflection energy to shallow reflection energy (attenuation ratio) is invariable at different frequencies. If a seismogram is decomposed into different frequency bands, these signals will show similar time–energy distributions. Therefore, the attenuation ratios should be similar across different frequency bands, except for frequency-variable weights. Nevertheless, the frequencyvariable weights for different frequency bands can be obtained by benchmarking against the time–energy distributions of low-frequency information because the loss of low-frequency information is relatively insignificant. In this light, we obtained frequency-variable weights for different frequencies and established a stratal absorption compensation (SAC) model. The anisotropic basis of the shearlet enables nearly optimal representation of curved-shape seismic signals, and shearlets at different scales can represent signals for different frequency bands. Then, we combined the SAC model with the shearlet transform and established the new compensation method. As the signal and noise have different distributions in the shearlet domain, we selectively compensated the signals using a thresholding algorithm. Hence, it was possible to avoid noise enhancement. This is the prominent advantage of the proposed method over other compensation methods.
EN
In order to detect the ultra-high-frequency (UHF) signals generated from partial discharges (PDs) in high voltage switchgear, a microstrip antenna sensor is designed. Influences of geometric parameters on the capability of the proposed antenna sensor are researched by numerical simulation. Measured characteristic results show that this antenna sensor is very suitable for partial discharge detection.
PL
W celu wykrycia sygnałów w zakresie ultra wysokich częstotliwości (UHF) generowanych przez wyładowania niezupełne (PD) w rozdzielnicy wysokonapięciowej zaprojektowano czujnik w postaci anteny. Wpływ parametrów geometrycznych przetwornika na jego własności został zbadany za pomocą symulacji numerycznych. Wyniki pomiarów pozwalają stwierdzić, że powyższy czujnik umożliwia skuteczne wykrycie wyładowań niezupełnych.
EN
In order to investigate the partial discharge characteristics, a needle-plate discharge model was proposed, which is built on the base of magneto-hydrodynamic (MHD) theory, is taken as an example. Based on this model, the distributions of coupling fields can be calculated. The simulation results are helpful for us to understand the fundamental characteristics in the process of partial discharge.
PL
W celu zbadania charakterystyk wyładowań niezupełnych zaproponowano model wyładowania igła-płyta zbudowany na bazie teorii magnetohydrodynamicznej (MHD). Na podstawie tego modelu możliwe jest obliczenie rozkładu pól sprzężonych. Wyniki symulacji są użyteczne do zrozumienia podstawowych charakterystyk w procesie wyładowania niezupełnego.
EN
In order to investigate the propagation characteristics of ultra-high-frequency (UHF) electromagnetic wave caused by partial discharge (PD) in high voltage switchgear, a simulation model was established by using the finite-difference-time-domain (FDTD) method. The simulation results have useful information for the installation of UHF sensor to detect PDs in switchgear.
PL
Opracowano model numeryczny i przeprowadzono symulacje metodą różnic skończonych w dziedzinie czasu (FDTD) w celu określenia charakterystyk propagacyjnych sygnałów w zakresie ultra wysokich częstotliwości (UHF) generowanych przez wyładowania niezupełne (PD) w rozdzielnicy wysokonapięciowej. Wyniki symulacji umożliwiają poprawną instalację czujników do wykrywania wyładowań niezupełnych w rozdzielnicy.
EN
Aiming at the overheating problem of cable joint, a 3-D finite element model of a single-core cable joint considering the coupling of electromagnetic field and temperature field has been built. In order to consider the heat losses generated by contact resistance of cable joint, the equivalent conductivity is calculated. The validity of the model and calculation method is verified by the comparison with analytical values.
PL
Do analizy zagadnienia przegrzania połączenia kablowego zbudowano trójwymiarowy model MES przy uwzględnieniu sprzężenia pola elektromagnetycznego i temperaturowego. W celu określenia strat ciepła wytwarzanego w rezystancji styku połączenia kablowego obliczono konduktywność zastępczą.
EN
The Salix variegata Franch. seedlings planted in the Three Gorges Reservoir (TGR) water level fluctuation zone (WLFZ) could survive after experiencing several seasons of winter submergence. We investigated the recovery mechanisms of S. variegata seedlings planted at the elevation of 168 m and 172 m in the TGR WLFZ after winter submergence. The results indicated that winter submergence caused some impacts on S. variegata seedlings with increases of hydrogen peroxide (H2O2), superoxide anions radical (O2-.), and malondialdehyde (MDA) levels, and decreases of antioxidant enzymatic systems during recovery stage after winter submergence. However, further analyses of relative water content (RWC), pigment content, proline content, carbohydrate content and several other antioxidant enzymatic activities (catalase (CAT), guaiacol peroxidase (G-POD), and glutathione peroxidase (GSH-POD)) showed that S. variegata seedlings were well recovered after winter submergence. These results indicate that S. variegata possesses strong winter submergence tolerance and adaptation to the specific hydrological environment in the TGR WLFZ. Therefore, S. variegata should be popularized as native tree species during the revegetation in the TGR WLFZ.
EN
Objectives: Our goal is to develop a double lumen cannula (DLC) for a percutaneous right ventricular assist device (pRVAD) in order to eliminate two open chest surgeries for RVAD installation and removal. The objective of this study was to evaluate the performance, flow pattern, blood hemolysis, and thrombosis potential of the pRVAD DLC. Methods: Computational fluid dynamics (CFD), using the finite volume method, was performed on the pRVAD DLC. For Reynolds numbers <4000, the laminar model was used to describe the blood flow behavior, while shear-stress transport k-ω model was used for Reynolds numbers >4000. Bench testing with a 27 Fr prototype was performed to validate the CFD calculations. Results: There was <1.3% difference between the CFD and experimental pressure drop results. The Lagrangian approach revealed a low index of hemolysis (0.012% in drainage lumen and 0.0073% in infusion lumen) at 5 l/min flow rate. Blood stagnancy and recirculation regions were found in the CFD analysis, indicating a potential risk for thrombosis. Conclusions: The pRVAD DLC can handle up to 5 l/min flow with limited potential hemolysis. Further modification of the pRVAD DLC is needed to address blood stagnancy and recirculation.
EN
A high performance distributed sensor system with multi-intrusions simultaneous detection capability based on phase sensitive OTDR (Φ-OTDR) has been proposed and demonstrated. To improve system performance, three aspects have been investigated. Firstly, a model of one-dimensional impulse response of backscattered light and a Monte Carlo method have been used to study how the laser line width affects the system performance. Theoretical and experimental results show that the performances of the system, especially the signal-noise-ratio (SNR), decrease with the broadening of laser linewidth. Secondly, a temperature-compensated fibre Bragg grating with a 3 dB linewidth of 0.05 nm and a wavelength stability of 0.1 pm has been applied as an optical filter for effective denoising. Thirdly, a novel interrogation method for multi-intrusions simultaneous detection is proposed and applied in data denoising and processing. Consequently, benefiting from the three-in-one improvement, a high performance Φ-OTDR has been realized and four simultaneous applied intrusions have been detected and located at the same time along a 14 km sensing fibre with a spatial resolution of 6m and a high SNR of 16 dB. To the best of our knowledge, this is the most multifunctional Φ-OTDR up to now and it can be used for perimeter and/or pipeline intrusion real-time monitoring.
EN
Hydroxyl-containing fluoroacrylate copolymers with different fluorine and hydroxyl concentrations were synthesized via free-radical solution polymerization. Transparent fluorinated polyurethane (FPU) films were prepared by curing the copolymers with HDI (hexamethylene diisocyanate) trimer. The Fourier transform infrared spectroscopy (FT-IR) results revealed introduction of fluorine both into the copolymer and polyurethane. X-ray photoelectron spectroscopy (XPS) analyses indicated that a gradient concentration of fluorine existed in the depth profile of the fluorinated polyurethane films. The highest contact angle (CA) was obtained for the FPU film with fluoroacrylate monomer concentration of 22 wt.% because of fluorine present on the film surface. The surface topographies detected by SEM and AFM indicated that surface roughness contributed little to the film hydrophobicity. By increasing the fluoroacrylate monomer concentration, the decreasing of crosslinking degree of hard segment resulted in lowering the first degradation temperature, while more C-F groups in soft segment led to higher second degradation temperature. UV-Vis spectrophotometer measurements indicated that the FPU film with the fluoroacrylate monomer concentration of 16 wt.% still had a high transmittance of more than 90 % in the whole visible wavelength range.
EN
We report the synthesis of PbF2:Er3+ particles using a hydrothermal method. The structure and upconversion emission properties of the products are investigated by scanning electron microscopy, X-ray diffractometer, Raman spectrophotometer and fluorescence spectrometry. An increase in Er3+ concentration in the crystals changes the PbF2 structure from a mixed phase to a cubic phase and decreases the grain size to nanoscale levels. Enhanced upconversion efficiency is achieved after annealing resulted from the formation of the cubic phase and the increase of grain size. The optimal Er3+ concentration is found to be 4% after annealing, and applied to the back of a bifacial silicon solar cell, maximum external quantum efficiencies of 0.38% and 0.79% are respectively obtained under 0.77 W/cm2 laser excitation (1560 nm) and AM1.5 + laser co-excitation.
EN
An all-fibre multi-parameter sensor for composite structures based on a chirped optical fibre Bragg grating (CFBG) has been studied theoretically and experimentally. The principle of multi-parameters sensing with a single CFBG is based on that the centre wavelength and the FWHM (full width at half maximum) in the reflection spectrum of a CFBG vary linearly with the temperature and/or the axial stress. A wavelength matched optical fibre long period grating (LPG) and another wavelength matched reference CFBG (CFBGR) have been used to interrogate the signal of the sensor CFBG (CFBGS). The temperature and strain of the composite structure have been monitored real-time with one CFBG as a single sensor head. The temperature resolution of 0.12ºC and the strain resolution of 1.1με for a composite structure have been realized in experiments. The experiment results agree well with the theoretical analyses.
EN
In fluid mechanics, to obtain the multiple solutions in ordinary differential equations is always a concerned and difficult problem. In this paper, a novel RNA genetic algorithm (NRNA-GA) inspired by RNA molecular structure and operators is proposed to solve the parameter estimation problems of the multiple solutions in fluid mechanics. This algorithm has improved greatly in precision and the success rate. Multiple solutions can be found through changing accuracy and search coverage and multi-iterations of computer. At last, parameter estimation of the ordinary differential equations with multiple solutions is calculated. We found that the result has great accuracy and this method is practical.
PL
W artykule zaproponowano nowy algorytm genetyczny NRNA-GA inspirowany strukturą molekularną RNA przeznaczony do rozwiązywania równań z wieloma rozwiązaniami w mechanice cieczy.
13
Content available remote A New Multi-objective Optimization Algorithm: MOAFSA and its Application
EN
This paper proposes a multi-objective artificial fish swarm algorithm (MOAFSA), which imitates the behaviors of fish for local search, uses the quick sort method to get non-dominated solution set, and cuts the external set according to the crowding distance. This paper firstly uses MOAFSA for multi-objective functions test. Results show that MOAFSA has a faster convergence speed and the corresponding Pareto set is more evenly distributed; then MOAFSA is applied in the scheduling optimization of hydropower station reservoir.
PL
Przedstawiono nowy algorytm optymalizacyjny MOAFSA (multiobjective artificial fish swarm algorithm) bazujący na ławicy ryb. Algorytm sprawdzono na przykładzie projektowania obciążeń hydroelektrowni.
EN
This paper is concerned with the fusion of information from process data and process connectivity and its subsequent use in fault diagnosis and process hazard assessment. The Signed Directed Graph (SDG), as a graphical model for capturing process topology and connectivity to show the causal relationships between process variables by material and information paths, has been widely used in root cause and hazard propagation analysis. An SDG is usually built based on process knowledge as described by piping and instrumentation diagrams. This is a complex and experience-dependent task, and therefore the resulting SDG should be validated by process data before being used for analysis. This paper introduces two validation methods. One is based on cross-correlation analysis of process data with assumed time delays, while the other is based on transfer entropy, where the correlation coefficient between two variables or the information transfer from one variable to another can be computed to validate the corresponding paths in SDGs. In addition to this, the relationship captured by data-based methods should also be validated by process knowledge to confirm its causality. This knowledge can be realized by checking the reachability or the influence of one variable on another based on the corresponding SDG which is the basis of causality. A case study of an industrial process is presented to illustrate the application of the proposed methods.
EN
The stems of Uncaria rhynchophylla (Miq.) ex Havil have a long history of use in traditional Chinese medicine to treat diseases and improve health. There is evident evidence that alkaloids constituents are mainly responsible for the beneficial effects of this plant medicine. The amounts of the major bioactive alkaloids in this plant vary widely with species, habitat, and as such, and establishment of a high-performance liquid chromatography (HPLC) fingerprint for quality control of this herbal medicine is of particular importance. The most alkaloids are used for medicine treatment and research. On the basis of the chromatographic data, a consistent HPLC fingerprint pattern containing 15 common peaks was obtained. Among these common peaks, four were identified as rhynchophylline, isorhynchophylline, corynoxeine, and isocorynoxeine. On the basis of this HPLC fingerprint and principal-components analysis, the quality of fifteen samples from different producing areas of China was objectively assessed. To summarize, the data described in this study offer valuable information for quality control and proper use of U. rhynchophylla (Miq.) ex Havil.
16
Content available remote Kinetic determination of Cr2O72- by chemical oscillation method
EN
The influence of Cr2O72-on the B-Z oscillating reaction has been studied. The research results have shown that B-Z oscillating reaction can be paused by Cr2O72- and the pause time can be used as a kinetic parameter in determination of Cr2O72- (when perturbed by particular chemicals, stable oscillating reaction is inhibited or paused; pause duration of the oscillation phenomenon is defined as a pause time). Under optimum experimental conditions, the pause time was linearly proportional to the concentration of Cr2O72-in the range 4.74 x 10-61.20x10-6 mol L-1 (r = 0.999), detection limit was 1.32 x 10 x10-8 L-1 The influence of more than 15 coexisting ions on determination of Cr2O72- was investigated in details. Most cations and anions had little effect on the determination results of Cr2O72-. A possible disturbance mechanism of Cr2O72- on the oscillating system was discussed. As a particularly efficient oxidant. Cr2O72- could consume Br quickly. Due to the extra consumption of Br. the B-Z oscillating reaction was inhibited, and therefore paused for a particular time (pause time). The higher the concentration of Cr2O72- was, the longer the pause time became, until the B-Z oscillating reaction was quenched completely.
PL
Badano wpływ Cr2O72- na reakcję oscylacyjną B-Z. Wyniki wskazywały, że reakcja może być przerwana pr/ez Cr2O72- a czas przerwy może być zastosowany jako kinetyczny parametr oznaczania Cr2O72- (gdy reakcja jest zaburzana przez jakiś dodatkowy składnik, stabilna oscylacja jest spowolniona lub przerwana a czas zaburzenia oscylacji jest określany jako czas pr/erwy). W optymalnych warunkach czas przerwy jest wprost proporcjonalny do stężenia Cr,O; w zakresie 4.74 x 10^-1.20 x I0~4 mol L~' (r = 0,999). granica wykrywalności 1.32 x 10"* mol L"'. Przebadano wpływ współwystępowania 15 różnych jonów na o/naczenie Cr2O72-. Większość kationów i anionów miała niewielki wpływ na oznaczanie Cr2O72-; . Przedyskutowano prawdopodobny mechanizm zaburzania reakcji oscylacyjnej przez Cr2O72- jako szczególnie efektywny utleniacz, mógł szybko usuwać join Br . / powodu zwiększonego usuwania jonów Br, reakcja oscylacyjna B-Z ulegała zahamowaniu i zatrzymywała się na pewien czas. Im większe było stężenie Cr2O72-, tym dłuższy był czas przerwy, aż do całkowitego wygaszenia reakcji oscylacyjnej B-Z.
EN
In this paper, a set of reliable devices and flowchart used for testing the potential of spontaneous combustion of sulfide ores (SOSC) are presented. An effective assessment method which depends upon the fire index system for evaluating the risk of SOSC in amining stope is introduced. To get more detailed information on self-heating situation in the ore dump at various period, the surface temperature on the ore dump is measured by an infra image apparatus and the temperature in the ore dump is analyzed both by ANSYS and FLUENT software. These results are visual and effective for applying correct measures for preventing the fire-breeding. Also, a group of chemical agents for abating the oxidized velocity are invented and can be sprayed into the ore dump. By integrating with all technical approaches described in above and using them for dealing with various practical conditions, the risk of SOSC in a stope can be effectively controlled.
PL
W niniejszym referacie, opisane zostały niezawodne urządzenia oraz schematy działań służące do badania potencjalnego samozapalenia się rudy siarczanu (SOSC). Przedstawiona została skuteczna metoda oceny służąca oszacowaniu ryzyka SOS C w przodku, która zależy od systemu wskaźnika pożarowości. Aby uzyskać bardziej szczegółowe informacje dotyczące samoogrzewania się hałdy rudy w różnych okresach, temperatura powierzchniowa na hałdzie mierzona jest za pomocą przyrządu na podczerwień, natomiast temperatura wewnątrz hałdy analizowana jest przy użyciu oprogramowania typu ANSYS oraz FLUENT. Wyniki tych badań są widoczne i użyteczne w celu zastosowania odpowiednich środków zapobiegających powstawaniu ognia. Wynalezione również zostały środki chemiczne służące spowolnieniu procesu utleniania, które mogą zostać rozpylone po powierzchni hałdy. Połączenie oraz praktyczne wykorzystanie wszystkich wyżej opisanych metod, może zapewnić efektywne kontrolowanie ryzyka samoistnego zapalenia się rudy siarczanu w przodku.
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