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991.
C. Yahaya M. S. Abd Latiff A. B. Mohamed 《International Journal of Communication Systems》2013,26(3):315-336
The exact contribution of this paper is a review of existing state‐of‐the‐art routing strategies for optical burst switched networks developed by researchers to deal with burst contention before it happens. Routing schemes are implemented in space domain, which make them simple and cost effective. Additionally, the paper points out the importance of routing as an effective way to deal with burst contention compared to other solutions. It also underlines the main differences between contention avoidance schemes and contention resolution techniques for optical burst switched networks. We believe that this review will help different optical burst switched researchers involved in the development of route optimization algorithms to control burst contention. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
992.
《Journal of Nuclear Science and Technology》2013,50(12):956-963
Optical trappings of ThO2 and UO2 particles have been first demonstrated in water using the radiation pressure of a TEM00-mode He-Ne laser beam of λ=633 nm. It was observed that a ThO2 particle was successfully trapped three-dimensionally in the focus region and transferred by moving the focus. On the other hand, for a UO2 particle of which a refractive index and an extinction coefficient are relatively large in the visible region, only two-dimensional trapping was observed when the beam focus was located near the bottom of the particle. One of the main difficulties in the optical trapping of nuclear fuel particles is attributed to their relatively large absorption coefficients in the visible region. Computational studies on three-dimensional optical trapping performances of absorbing particles were, therefore, perfomed with a simulation code based on geometrical optics. The present calculation can well predict the experimental results on the optical trapping characteristics for ThO2 and UO2 particles. 相似文献
993.
《Journal of Nuclear Science and Technology》2013,50(5):351-358
Empirical studies of coherences between measurement variables from the operating data of a commercial nuclear power station of 460 MWe are applied to derive dynamical characteristics of the Boiling Water Reactor and to attempt to identify the noise sources of the neutron flux. Multivariate techniques with the partial coherence function and the multiple coherence function are introduced to eliminate correlated effects among measurement variables due to thermal hydraulic coupling and sophisticated reactivity feedbacks. From the results, the usual coherency (the ordinary coherence function) may not be adequate to estimate linear relations between measurement variables of the BWR. Furthermore, the noise sources of the neutron flux is discussed. 相似文献
994.
Abstract Ownership costs of operational aircraft have increased steadily over the years. One of the major cost drivers is structural deterioration due to corrosion. Beyond the economics, finding and characterizing corrosion is essential for the continued airworthiness of aircraft fleets. To this end, the pulsed eddy current technique holds the potential of becoming the primary means of detecting corrosion in multilayered structures. Its wide-band frequency spectrum allows the determination of a large number of parameters, such as defect size and location. Pulsed eddy current is still considered an experimental nondestructive technique because of realistic inspection problems (e.g., probe tilting, protrusion of rivets, and thickness variations in adhesive and paint) have not been addressed in the past. Recent advances change this situation and allow pulsed eddy current to be a credible field technique. 相似文献
995.
Yoshihiro Maruyama Takumi Hamaguchi Tien-Hsiu Tsai 《Journal of Nuclear Science and Technology》2018,55(2):199-208
A new ‘transXend’ detector system has been developed for energy-resolved computed tomography (CT). It consists of several segmented detectors that measure X-rays as electric currents. Response functions of segmented detectors are estimated using component materials of a body under inspection to unfold X-ray spectra. To avoid material-dependent measurements, response functions inherent to segmented detectors are evaluated by Monte Carlo calculations. CT was performed for a phantom consisting of five resins and was analyzed by the estimated response functions. The linear attenuation coefficients for the five resins have excellent agreement with database values. 相似文献
996.
Tien-Hsiu Tsai Takumi Hamaguchi Ikuo Kanno 《Journal of Nuclear Science and Technology》2018,55(6):663-671
The filter-type ‘transXend’ detector is an energy-resolving X-ray detector consisting of an energy-integrating flat-panel detector and multiple filters. In our previous studies, we have shown the effectiveness of the transXend detector, but the filters used were not optimized. To obtain better performance, the filters, especially their thickness and material, should be considered. In this paper, we present a method that can preliminarily estimate filter performance by comparing their noise sensitivity before carrying out numerous experiments. Two kinds of filter sets, Cu–Sn and W–Ag, with various thicknesses were evaluated. The results suggest that to image a 20-cm-thick object with 120-kV X-rays, an unfiltered channel and a channel filtered with 0.5-mm-thick Sn or 0.4-mm-thick Ag may be the best combination. The optimal filter thickness will be smaller if the object is thinner and the tube voltage is lower. For applications that require a wide dynamic range of detector response, a channel with a W filter may be better than an unfiltered channel. To verify the calculation results, computed tomography imaging experiments with a 3-cm-diameter phantom were also performed, and the experimental results showed good agreement with the calculation results. 相似文献
997.
Shinsuke Nakayama 《Journal of Nuclear Science and Technology》2018,55(6):614-622
Toward the development of the next version of Japanese Evaluated Nuclear Data Library (JENDL) general-purpose file, we calculate neutron cross-sections on 63, 65Cu from 50 keV to 20 MeV, which is the incident energy range above the resolved resonance region in JENDL-4.0. A dispersive optical model potential is adopted with a coupled-channel method for interaction between neutron and 63, 65Cu. Direct, pre-equilibrium, and compound processes are taken into account in the calculation. All cross-sections, differential and double-differential cross-sections are consistently calculated with a single set of model parameters. The calculation results reproduce the measured data very well. In addition, disagreement between the calculated and experimental values seen in an integral test for the 63Cu(n, α)60Co reaction is improved by using the cross-section data obtained from the present work. 相似文献
998.
Sefer Bora Lisesivdin Nadir Ali Khan Simone Mazzucato Naci Balkan Michael John Adams Ville-Markus Korpij?rvi Mircea Guina Gabor Mezosi Marc Sorel 《Nanoscale research letters》2014,9(1):22
We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain. 相似文献
999.
《Fusion Engineering and Design》2014,89(11):2659-2665
This visible light computerized tomography exercise is a part of a project to establish an auxiliary imaging method to assist other imaging facilities at the Institute of Plasma Research (IPR), India. Space constraints around Aditya Tokamak allow only two orthogonal ports. Each port has one detector array (64 sensors) sensitive to the visual spectrum emitted by Hα emission. The objective here is to report the developments on limited view tomography for hot plasma imaging. Spatially filtered entropy maximization algorithm with non-uniform discretization grids is employed. Estimation of unique kernel smoothening parameters (mask size and exponent factor) depends on entropy function and projection data. It removes requirement of any arbitrary/user-based decision for choosing a regularization factor thus minimizes the chance for biasedness or errors. Synthetic projection data is used to analyse the performance of this modification. The error band in the process of recovery remains under acceptable level (less than 15%) irrespective of the origin of the emissions from the core. Reconstructed hot plasma images/profiles from Aditya Tokamak are shown. These profiles may improve the current understanding about (a) plasma–wall interaction or edge plasma turbulence, (b) control and generation of plasma and (c) correlations between theoretical and engineering advancements in Tokamak reactors. 相似文献
1000.
Jiasong Zhong Weidong Xiang Zhaoping Chen Haijun Zhao Xiaojuan Liang 《Materials Science and Engineering: B》2013,178(15):998-1003
Cu nanocrystals embedded in sodium borosilicate glass of varied Cu contents from 0.5 to 1.5 wt% have been successfully prepared through a sol–gel process. According to the results of X-ray diffraction (XRD) and the energy dispersive X-ray spectrometry (EDS), the metal Cu nanocrystals in cubic crystal system were well distributed inside glass matrix. Fourier Transform Infrared (FTIR) indicated the sodium borosilicate matrix had no major structural change for gels with different Cu contents. The optical absorption peaks due to the surface plasmon resonance of Cu particles were observed in the wavelength range of 550–600 nm. The absorption peak showed a red-shift trend with increasing Cu contents from 0.5 to 1.5 wt%. Transmission electron microscopy (TEM) revealed the existence of spherical Cu nanocrystals in the matrix. The diameter of Cu nanocrystals varied from 1 to 3.5 nm. Furthermore, the third-order nonlinear optical properties were investigated by Z-scan technique at 800 nm. Experimental results indicated the Cu nanocrystals have obvious positive refractive nonlinearities and reverse saturated absorption performance. 相似文献