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排序方式: 共有320条查询结果,搜索用时 578 毫秒
1.
Ultrafast time-domain technology and its application in all-optical signal processing 总被引:1,自引:0,他引:1
Vlachos K. Pleros N. Bintjas C. Theophilopoulos G. Avramopoulos H. 《Lightwave Technology, Journal of》2003,21(9):1857-1868
In this paper, we review recent advances in ultrafast optical time-domain technology with emphasis on the use in optical packet switching. In this respect, several key building blocks, including high-rate laser sources applicable to any time-division-multiplexing (TDM) application, optical logic circuits for bitwise processing, and clock-recovery circuits for timing synchronization with both synchronous and asynchronous data traffic, are described in detail. The circuits take advantage of the ultrafast nonlinear transfer function of semiconductor-based devices to operate successfully at rates beyond 10 Gb/s. We also demonstrate two more complex circuits-a header extraction unit and an exchange-bypass switch-operating at 10 Gb/s. These two units are key blocks for any general-purpose packet routing/switching application. Finally, we discuss the system perspective of all these modules and propose their possible incorporation in a packet switch architecture to provide low-level but high-speed functionalities. The goal is to perform as many operations as possible in the optical domain to increase node throughput and to alleviate the network from unwanted and expensive optical-electrical-optical conversions. 相似文献
2.
3.
C. Deslouis O. Gil B. Tribollet G. Vlachos B. Robertson 《Journal of Applied Electrochemistry》1992,22(9):835-842
The reduction of dissolved oxygen has been studied over a wide conductivity range for use in steady or nonsteady hydrodynamic measurements. Mass transfer fluctuations can be analysed statistically to obtain the power spectra of hydrodynamic fluctuations. This requires a consideration of the proton reduction, which prevents diffusion from limiting the current. The transfer function for deducing the hydrodynamic spectra from mass transfer spectra includes not only transport effects but also kinetic effects which account for the finite rate of the reaction. The experimental study was performed using electrohydrodynamic (EHD) impedance. 相似文献
4.
Michail V. Kozlov Junwei Zhu Peter Philipp Wittko Francke Elena L. Zvereva Bill S. Hansson Christer Löfstedt 《Journal of chemical ecology》1996,22(3):431-454
The fifth abdominal segment of femaleEriocrania semipurpurella (Stephens) andE. sangii (Wood) contains a pair of exocrine glands. Hexane extracts of this segment were prepared from both species and analyzed by gas chromatography with simultaneous flame ionization and electroantennographic detection (EAD). For both species, the EAD active peaks were identified as nonan-2-one, (Z)-6-nonen-2-one, and (Z)-6-nonen-2-ol by means of mass spectrometry and comparison of retention indices with those of synthetic standards. Enantiomeric separation of chiral alcohols from the female extracts was achieved by gas chromatographic analysis on a cyclodextrin column. InE. semipurpurella, a mixture of (2S,6Z)-nonen-2-ol and (2R,6Z)-nonen-2-ol (2: I) was found, whereas inE. sangii (2S,6Z)-nonen-2-ol was the predominant enantiomer and only traces of theR enantiomer were indicated by the antennal response. In field tests, a blend of the three compounds was not attractive to conspecific males. A subtractive assay showed that the alcohol in various enantiomeric mixtures was the only attractive compound, whereas addition of (Z)-6-nonen-2-one to the alcohol completely inhibited the attraction of both species. A trapping experiment including a wide range of ratios between theR andS enantiomers showed that baits containing 95–100% of theS enantiomer were attractive to maleE. sangii, whereas males ofE. semipurpurella were attracted to all tested ratios of the enantiomers. However, the response profiles of maleE. semipurpurella differed between populations from southern Sweden, south Finland, and the Kola Peninsula in Russia. In south Sweden males were maximally attracted to a racemic mixture of the alcohols. At the Kola PeninsulaE. semipurpurella was attracted to baits containing 95–100% of theR enantiomer. In south Finland all tested ratios between 0 and 100%R enantiomer trappedE. semipurpurella, but the trap catches appeared to be bimodally distributed with peaks around 15 and 70%R enantiomer. The trapping results suggest the existence of pheromone races or sibling species among the specimens identified asE. semipurpurella.Dedicated to Prof. H. J. Bestmann on the occasion of his 70th birthday. 相似文献
5.
Dmitry V. Orekhov Oleg A. Kazantsev Sergey V. Orekhov Alexey P. Sivokhin Denis M. Kamorin Alexander S. Simagin Maria V. Savinova Evgeniya A. Bolshakova Michail S. Korotaev 《应用聚合物科学杂志》2021,138(38):50982
Thermoresponsive PEG-based (PEG stands polyethylene glycol) polymers are unique for use in medicine because of their low toxicity, good biocompatibility and biodegradability, but usually more hydrophobic and more toxic comonomers are used to adjust lower critical solution temperature (LCST). A convenient way to overcome this problem and to finely tune LCST is to use alkoxy oligo(ethylene glycol)- or alkoxy oligo(propylene glycol) (meth)acrylates as starting comonomers. Here we report on the conditions for the simple and affordable synthesis of methoxy oligo(propylene glycol) (meth)acrylate- and methoxy oligo(propylene glycol)-block-oligo(ethylene glycol) (meth)acrylate-based macromonomers with high yields (80%–98.7%) by the acid-catalyzed esterification of (meth)acrylic acid with alkoxy oligo(alkylene glycols) containing oligo(ethylene glycol) (OEG) and/or oligo(propylene glycol) (OPG) blocks. p-Toluene sulphonic acid (pTSA), alkyl(C12–C14)benzene sulfonic acid (ABSA) and H2SO4 were used as catalysts. It has been shown that pTSA and ABSA are practically the same in catalytic activity and are superior to sulfuric acid. The reaction orders with respect to catalyst was found to be close to 1 in all cases. It has been shown that the reaction is actually insensitive to the lengths of OEG and OPG blocks, as well as to the structure of the terminal alkyl group, while the esterification of acrylic acid (AA) proceeds much faster compared to methacrylic acid (MAA) one under the same conditions. The influence of temperature on the equilibrium conversions of alcohols was determined, which were found to be 89%–93% for the esterification of AA and 61%–86% for MAA in the temperature range of 60–120°C. A further increase in conversion was achieved by introducing an azeotropic agent (toluene), its optimal concentration was found to be 10%–15%. 相似文献
6.
Maria S. Parshina Alexander N. Tarasenkov Rinat R. Aysin Nadezhda A. Tebeneva Michail I. Buzin Egor S. Afanasyev Olga A. Serenko Aziz M. Muzafarov 《应用聚合物科学杂志》2021,138(36):50918
In this work, the curing of «ED-20» epoxy resin with partially siloxy-substituted aluminum, iron, and zirconium siloxanes that we obtained previously was studied. The initial content of a metallosiloxane in the compositions was 5–50 wt% with respect to the resin. In all the cases, thermal curing was used to obtain a series of samples in the form of solid homogeneous materials. The fact of the epoxy ring opening in the resin was confirmed by IR spectroscopy. The catalytic properties of the metal atom in a metallosiloxane were found to affect the curing process. The samples demonstrate rather a high resistance to thermooxidative destruction, and in most cases, their glass transition temperatures are lower than those obtained upon standard curing of «ED-20» resin with triethylenetetramine. Partially siloxy-substituted metalloalkoxysiloxanes can be efficient agents for curing and formation of a hybrid material based on epoxy resins. 相似文献
7.
Several researchers have recently investigated the connection between reinforcement learning and classification. We are motivated
by proposals of approximate policy iteration schemes without value functions, which focus on policy representation using classifiers
and address policy learning as a supervised learning problem. This paper proposes variants of an improved policy iteration
scheme which addresses the core sampling problem in evaluating a policy through simulation as a multi-armed bandit machine.
The resulting algorithm offers comparable performance to the previous algorithm achieved, however, with significantly less
computational effort. An order of magnitude improvement is demonstrated experimentally in two standard reinforcement learning
domains: inverted pendulum and mountain-car. 相似文献
8.
Michail Papathomas 《TEST》2018,27(1):197-220
Consider a set of categorical variables where at least one of them is binary. The log-linear model that describes the counts in the resulting contingency table implies a specific logistic regression model, with the binary variable as the outcome. Within the Bayesian framework, the g-prior and mixtures of g-priors are commonly assigned to the parameters of a generalized linear model. We prove that assigning a g-prior (or a mixture of g-priors) to the parameters of a certain log-linear model designates a g-prior (or a mixture of g-priors) on the parameters of the corresponding logistic regression. By deriving an asymptotic result, and with numerical illustrations, we demonstrate that when a g-prior is adopted, this correspondence extends to the posterior distribution of the model parameters. Thus, it is valid to translate inferences from fitting a log-linear model to inferences within the logistic regression framework, with regard to the presence of main effects and interaction terms. 相似文献
9.
Athanasios Vlachos Vassilis Fotopoulos Athanassios N. Skodras 《Journal of Real-Time Image Processing》2010,5(3):141-148
A comparative study of low complexity motion estimation algorithms is presented. The algorithms included in the study are
the 1-bit transform, the 2-bit transform, the constrained 1-bit transform and the multiplication free 1-bit transform which
are using different motion estimation strategies compared to standard exhaustive search algorithm-mean absolute difference
or similar combinations. These techniques provide better performance in terms of computational load compared to traditional
algorithms. Although the accuracy of motion compensation is only slightly lower comparing to the other techniques, results
in terms of objective quality (peak signal-to-noise ratio) and entropy are comparable. This fact, nominates them as suitable
candidates for inclusion in embedded devices applications where lower complexity translates to lower power consumption and
consequently improved device autonomy. 相似文献
10.
Panagiotis Vlachos 《Computer Physics Communications》2009,180(10):1990-1998
We present a general two-player quantum game simulator that can simulate any two-player quantum game described by a 2×2 payoff matrix (two strategy games).The user can determine the payoff matrices for both players, their strategies and the amount of entanglement between their initial strategies. The outputs of the simulator are the expected payoffs of each player as a function of the other player's strategy parameters and the amount of entanglement. The simulator also produces contour plots that divide the strategy spaces of the game in regions in which players can get larger payoffs if they choose to use a quantum strategy against any classical one. We also apply the simulator to two well-known quantum games, the Battle of Sexes and the Chicken game.