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71.
In this paper densities for THF (tetrahydrofuran) and THF + water mixtures measured with the help of the Anton Paar DMA HPM vibrating tube densimeter are reported. The pure component densities of tetrahydrofuran measured in the temperature range from 278 to 437 K and pressures up to 130 MPa were correlated with the TRIDEN-System. Additionally densities of the binary mixture tetrahydrofuran + water were measured for 6 different concentrations in a temperature range from 288 to 338 K and up to 130 MPa. Excess volumes (vE) of the mixture were determined using the own correlation of the tetrahydrofuran densities and the equation of state (EoS) for water by Wagner and Pruß. Redlich–Kister polynomials were used to fit the vE-data. Additionally in this work it was checked if the vibrating tube densimeter allows the determination of the miscibility gap for the system THF–water as a function of temperature and pressure. 相似文献
72.
Wenjun Tang Dr. Andrew G. Capacci Xudong Wei Dr. Wenjie Li Dr. Andre White Dr. Nitinchandra D. Patel Jolaine Savoie Joe J. Gao Sonia Rodriguez Dr. Bo Qu Dr. Nizar Haddad Dr. Bruce Z. Lu Dr. Dhileepkumar Krishnamurthy Dr. Nathan K. Yee Dr. Chris H. Senanayake Dr. 《Angewandte Chemie (International ed. in English)》2010,49(34):5879-5883
73.
74.
Schmid JH Ibrahim M Cheben P Lapointe J Janz S Bock PJ Densmore A Lamontagne B Ma R Ye WN Xu DX 《Optics letters》2011,36(11):2110-2112
We demonstrate, by experiment and numerical calculations, temperature-independent subwavelength grating waveguides with a periodic composite core composed of alternating regions of silicon and SU-8 polymer. The polymer has a negative thermo-optic (TO) material coefficient that cancels the large positive TO effect of the silicon. Measurements and Bloch mode calculations were carried out over a range of silicon-polymer duty ratios. The lowest measured TO coefficient at a wavelength of 1550 nm is 1.8×10(-6) K(-1); 2 orders of magnitude smaller than a conventional silicon photonic wire waveguide. Calculations predict the possibility of complete cancellation of the silicon waveguide temperature dependence. 相似文献
75.
By varying the absorption coefficient and width of an intralipid-India ink solution in a quasi-one-dimensional experiment, we investigate the transition between the ballistic and the diffusive regimes. The medium's attenuation coefficient changes abruptly between two different values within a single mean free path. This problem is analyzed both experimentally and theoretically, and it is demonstrated that the transition location depends on the scattering coefficient as well as on the measuring solid angle. 相似文献
76.
Andre L. Barbieri G.F. de Arruda Francisco A. Rodrigues Odemir M. Bruno Luciano da Fontoura Costa 《Physica A》2011,390(3):512-518
An entropy-based image segmentation approach is introduced and applied to color images obtained from Google Earth. Segmentation refers to the process of partitioning a digital image in order to locate different objects and regions of interest. The application to satellite images paves the way to automated monitoring of ecological catastrophes, urban growth, agricultural activity, maritime pollution, climate changing and general surveillance. Regions representing aquatic, rural and urban areas are identified and the accuracy of the proposed segmentation methodology is evaluated. The comparison with gray level images revealed that the color information is fundamental to obtain an accurate segmentation. 相似文献
77.
David Bergman Andre A. Cire Willem-Jan van Hoeve Tallys Yunes 《Journal of Heuristics》2014,20(2):211-234
In this paper we introduce a new method for generating heuristic solutions to binary optimization problems. We develop a technique based on binary decision diagrams. We use these structures to provide an under-approximation to the set of feasible solutions. We show that the proposed algorithm delivers comparable solutions to a state-of-the-art general-purpose optimization solver on randomly generated set covering and set packing problems. 相似文献
78.
Alexander A. Kaminskii Ludmila Li Andre V. Butashin Vladimir S. Mironov Alexsei A. Pavlyuk Sergey N. Bagayev Ken-ichi Ueda 《Optical Review》1997,4(2):309-315
Monoclinic KY(WO4)2:Pr3+, Tm3+:KY(WO4)2:Er3+, Yb3+ single crystals are grown by low-gradient Czochralski technique. Stimulated emission at 1.0223μm wavelength in the new lasing 1D2→3F3 channel of Pr3+ ions in KY(WO4)2 at room temperature under Xe-flashlamp pumping is excited. Full sets of Stark-level energies for Pr3+ ions in KY(WO4)2 and KGd(WO4)2 crystals at 77 K are determined. 4f2-4f2 intensity-transitions for the KY(WO4)2:Pr3+ are analyzed preliminarily. All observed at present and earlier one-micron Pr3+-ion, induced transitions in the 1D2→3F3 and 1D2→3F4 channels are identified. In yttrium and gadolinium sensitized-tungstates a two-micron (3H4→3H6) low-threshold generation of Tm3+ ions at cryogenic temperatures is achieved.All authors cooperate with the Joint Open Laboratory for Laser Crystals and Precise Laser Systems at the Institute of Crystallography and Institute of Laser Physics, Russian Academy of Sciences. 相似文献
79.
We apply a stochastic center manifold method to the calculation of noise-induced phase transitions in the stochastic Swift-Hohenberg equation. This analysis is applied to the reduced mode equations that result from Fourier decomposition of the field variable and of the temporal noise. The method shows a pitchfork bifurcation at lower perturbation order, but reveals a novel additive-noise-induced postponement of the Turing bifurcation at higher order. Good agreement is found between the theory and the numerics for both the reduced and the full system. The results are generalizable to a broad class of nonlinear spatial systems. 相似文献
80.
Dr. Georgian Melinte Dr. Veselina Georgieva Dr. Marie‐Anne Springuel‐Huet Dr. Andreï Nossov Prof. Ovidiu Ersen Dr. Flavien Guenneau Prof. Antoine Gedeon Dr. Ana Palčić Dr. Krassimir N. Bozhilov Dr. Cuong Pham‐Huu Prof. Shilun Qiu Dr. Svetlana Mintova Dr. Valentin Valtchev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18316-18327
The principle aspects and constraints of the dynamics and kinetics of zeolite nucleation in hydrogel systems are analyzed on the basis of a model Na‐rich aluminosilicate system. A detailed time‐series EMT‐type zeolite crystallization study in the model hydrogel system was performed to elucidate the topological and temporal aspects of zeolite nucleation. A comprehensive set of analytical tools and methods was employed to analyze the gel evolution and complement the primary methods of transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR) spectroscopy. TEM tomography reveals that the initial gel particles exhibit a core–shell structure. Zeolite nucleation is topologically limited to this shell structure and the kinetics of nucleation is controlled by the shell integrity. The induction period extends to the moment when the shell is consumed and the bulk solution can react with the core of the gel particles. These new findings, in particular the importance of the gel particle shell in zeolite nucleation, can be used to control the growth process and properties of zeolites formed in hydrogels. 相似文献