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排序方式: 共有465条查询结果,搜索用时 15 毫秒
31.
L. Fuentes K. Feldmann K. Walther L. P. Drechsler I. Doerfel E. N. Vlassova V. I. Matorin M. Betzl 《Crystal Research and Technology》1987,22(3):449-454
In the present work the connection between magnetic properties and texture of two samples of the tetragonal Mn Al phase is investigated. The specimens have been prepared by different cold deformation methods to get various texture types. For texture analysis neutron time-of-flight technique has been applied. Some aspects of the mathematical treatment of experimental data has been discussed. The main texture components in the inverse pole figures are inclined with respect to the direction of easy magnetization. Therefore, improved magnetic properties of the material can be expected using more optimal preparation techniques. 相似文献
32.
In mobile edge computing systems, the edge server placement problem is mainly tackled as a multi-objective optimization problem and solved with mixed integer programming, heuristic or meta-heuristic algorithms, etc. These methods, however, have profound defect implications such as poor scalability, local optimal solutions, and parameter tuning difficulties. To overcome these defects, we propose a novel edge server placement algorithm based on deep q-network and reinforcement learning, dubbed DQN-ESPA, which can achieve optimal placements without relying on previous placement experience. In DQN-ESPA, the edge server placement problem is modeled as a Markov decision process, which is formalized with the state space, action space and reward function, and it is subsequently solved using a reinforcement learning algorithm. Experimental results using real datasets from Shanghai Telecom show that DQN-ESPA outperforms state-of-the-art algorithms such as simulated annealing placement algorithm (SAPA), Top-K placement algorithm (TKPA), K-Means placement algorithm (KMPA), and random placement algorithm (RPA). In particular, with a comprehensive consideration of access delay and workload balance, DQN-ESPA achieves up to 13.40% and 15.54% better placement performance for 100 and 300 edge servers respectively. 相似文献
33.
Emília Valena Ferreira de Arago Luca Mancini Noelia Faginas-Lago Marzio Rosi Dimitrios Skouteris Fernando Pirani 《Molecules (Basel, Switzerland)》2022,27(7)
The reaction between the cyano radical CN and cyanoacetylene molecule HCN is of great interest in different astronomical fields, from star-forming regions to planetary atmospheres. In this work, we present a new synergistic theoretical approach for the derivation of the rate coefficient for gas phase neutral-neutral reactions. Statistic RRKM calculations on the Potential Energy Surface are coupled with a semiempirical analysis of the initial bimolecular interaction. The value of the rate coefficient for the HCN + CN → H + NCCCCN reaction obtained with this method is compared with previous theoretical and experimental investigations, showing strengths and weaknesses of the new presented approach. 相似文献
34.
F. Barbadillo A. Fuentes S. Naya R. Cao J. L. Mier R. Artiaga 《Journal of Thermal Analysis and Calorimetry》2007,87(1):223-227
The aim of this paper is to evaluate and explain the fitting of dynamic
TG curves by a mixture of logistic functions. This model assumes that more
than one physical process may be involved in each mass loss step and that
each physical process may extend along all the experiment. One of the main
sources of difficulties in TG is that, very often, different stages of decomposition
substantially overlap each other. Several real and simulated TG curves were
analysed in this paper. An optimal fitting of the TG curves was obtained by
a mixture of logistics. In many cases the optimal fitting reproduces accurately
the TG curve. Accordingly, the TG curve can be understood as a sum of parallel
reactions, where each single reaction is represented by one or a small number
of logistic components. Additionally, making use of the analytical derivative
of the fitting, a mixture of Arrhenius reaction order equations was applied
to the same curves. In all the cases, the fitting obtained with the mixture
of Arrhenius was worse than the obtained with the mixture of logistics. A
software was developed to automatically perform these tasks. The physical
meaning of the fitting was explained. 相似文献
35.
R.A. Zárate S. Fuentes V.M. Fuenzalida 《Journal of Physics and Chemistry of Solids》2007,68(4):628-637
Fine titanium dioxide particles were hydrothermally treated in a sodium hydroxide aqueous solution. The treatment extended from 1 to 6 days leading to belt-like and wire-like structures of a metastable phase of sodium titanate, with typical widths and diameters between 8 and 40 nm, and lengths from 100 nm to several micrometers. These conclusions are supported by X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy. The latter method revealed two set of space fringes with characteristic distances of 0.29 and 0.34 nm. These distances could correspond to the lattice spacing of and planes in Na2Ti6O13 compounds. The nanomaterial was found to be stable up to temperatures as high as 200 or depending on the reaction time and the concentration. 相似文献
36.
Elena Fernández Manuel Ortuño Andrés Márquez Rosa Fuentes Inmaculada Pascual 《Optik》2010,121(2):151-158
Holographic data pages were stored in a polyvinyl alcohol (PVA)/acrylamide (AA) photopolymer. This material is formed of AA photopolymers which are considered interesting materials for recording holographic memories. A liquid crystal device was used to modify the object beam and store the data pages in the material. During the storage process, some parameters like exposure time, beam ratio and reading beam intensity were controlled to obtain high image quality after the reconstruction process. The bit error rate (BER) was calculated fitting the histograms of the images to determine what parameters improve the quality of the images. 相似文献
37.
J. L. Jiménez Pérez E. Rangel Vargas R. Gutiérrez Fuentes A. Cruz-Orea H. Bautista de León 《The European physical journal. Special topics》2008,153(1):511-513
In this paper we used thermal lens spectrometry to
determine the thermal diffusivity of cheese fats. We have used equal
concentrations of cheese fats from oaxaca, chihuahua, gouda, manchego and
mozzarella cheeses at 42°C temperature. The two lasers
mismatched mode experimental configuration was used with a He-Ne laser, as a
probe beam and an Ar+ laser as the excitation one. The characteristic
time constant of the transient thermal lens was obtained by fitting the
theoretical expression to the experimental data in order to obtain the
thermal diffusivity of the cheese fat samples. This measured thermal
property may contribute to a better understanding of the cheese fats
quality, which is very important in food industry. 相似文献
38.
The reaction of malononitrile with α-phenylcinnamonitriles in ethanolic sodium ethanethiolate is studied as a convenient route to 2-amino-4-aryl-5-cyano-6-ethylthio-3-phenyl-3,4-dihydropyridines ( 5 ) and the corresponding pyridines 6 . From the study of the structure of 5a (Ar = Ph) we can conclude that this cyclization reaction proceeds via a site-selective addition of the ethanethiolate to the cyano group i of the 1,3-tricarbonitrile ( 2 ). 相似文献
39.
Legros G Fuentes A Ben-Abdallah P Baillargeat J Joulain P Vantelon JP Torero JL 《Optics letters》2005,30(24):3311-3313
A remote scanning retrieval method was developed to investigate the soot layer produced by a laminar diffusion flame established over a flat plate burner in microgravity. Experiments were conducted during parabolic flights. This original application of an inverse problem leads to the three-dimensional recomposition by layers of the absorption field inside the flame. This technique provides a well-defined flame length that substitutes for other subjective definitions associated with emissions. 相似文献
40.