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We study the relaxation limit for the Aw-Rascle system of traffic flow. For this we apply the theory of invariant regions and the compensated compactness method to get global existence of Cauchy problem for a particular Aw-Rascle system with source, where the source is the relaxation term, and we show the convergence of this solutions to the equilibrium state. 相似文献
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Changes in the nature of the binding site of chemisorbed CO on the Rh{111} and Rh{331} single crystal surfaces during adsorption and desorption have been monitored by X-ray Photoelectron Spectroscopy (XPS) and Low Energy Electron Diffraction (LEED). Two bonding states of molecular CO have been identified from the O 1s photoemission line. These states are assigned as atop and bridge-bonded species and are observed to be coverage and temperature dependent. On both surfaces atop sites are populated first and at higher CO coverages bridge sites are filled. On Rh{111} the bridge sites are filled at a CO coverage of θCO ~ 0.50 and their presence is correlated with a change in the LEED pattern. The presence of the step atoms on the Rh{331} surface markedly influenced the sequential filling of binding sites in comparison to that observed on the Rh{111} surface. A comparison of our data to previous Electron Energy Loss Spectroscopy (EELS) work on Rh{111} is in remarkable quantitative agreement with EELS peak heights. 相似文献
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使用均苯三甲酸与碳酸镍在水热条件下反应得到了一例新的二维双层Ni(II)配位聚合物Ni3(BTC)2(μ-H2O)26H2O。二维层包含syn-syn羧酸桥和水桥连接的三核Ni3单元,进一步用均苯三甲酸上的苯环连接成二维层状结构。磁性研究表明,相邻Ni2+离子间存在弱的铁磁耦合作用。水桥连镍离子的桥联键角为122.8(3)deg,所以通过该水桥镍离子间应该呈现反铁磁耦合。因此,实验结果证明了syn-syn羧酸桥传递铁磁耦合,而且铁磁耦合大于反铁磁作用,最终配合物呈弱的铁磁耦合。基于本工作和文献报道的含syn-syn 羧酸混合桥联镍配合物的磁性,我们总结出下面结论:Ni–O–C–O–Ni的共面性与否决定了配合物的磁性。共面性好的Ni–O–C–O–Ni导致中等强度的反铁磁耦合,而共面性差会消弱反铁磁作用,甚至出现由反铁磁变为铁磁耦合。标题配合物中羧酸桥所传递的铁磁性可能就归因于Ni–O–C–O–Ni的不共平面性。因此,与含羧酸桥的混合桥联双核铜(II)配合物类似,轨道补偿效应(the orbital complementary effect (OCE))对于解释水/羧酸混合桥联镍(II)配合物的磁性也同样适用。 相似文献
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Coherent Dynamics of Direct-Current-Driven Quantum-Dot-Array with Two Time-Dependent Embedded Impurities
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The coherent dynamics of dc-driven quantum-dot array with two embedded time-dependent impurities is investigated, the exact crossings and avoided crossings in the quasienergies are associated with the evolution dynamics of the electron by the introduction of the envelope lines of the site's maximum returning probability. Through a perturbative scheme, the time-dependent Hamiltonian is replaced by an equivalent static one, whose structure reveals the new quantum tunnelling mechanism in the time-periodic driving system and sheds light on the alternative interpretation of dynamic localization and delocalization. 相似文献
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Ceren ATLA DNER Ceren G
KALP Bengü GETREN Atila YILDIZ Nuray YILDIZ 《Turkish Journal of Chemistry》2021,45(4):1248
Usnic acid (UA) was extracted from Usnea longissima (L.) Ach. in supercritical carbon dioxide (SC-CO2) medium. The selected process parameters were extraction temperature (35–45 °C), amount of co-solvent (0%–5%) and extraction time (5–9 h). These parameters were applied to Box-Behnken design (BBD) belonging to response surface methodology (RSM) to determine optimum process parameters for the highest amount of UA in the extract. g UA/100g lichen, extraction yield % and UA content values were calculated in the range of 0.045–0.317, 2.77–5.4 and 71%–82% in different experimental conditions, respectively. The optimum conditions were predicted as 42 °C, 4.3% (ethanol) and 7.48 h. It was determined that the predicted and experimental values of g UA/100g lichen were compatible, and the suggested model was valid. 相似文献
39.
J. MEDINA YU. G. GUREVICH G. N. LOGVINOV P. RODRÍGUEZ G. GONZÁLEZ DE LA CRUZ 《Molecular physics》2013,111(19):3133-3138
The problem of the effective thermal diffusivity of two-layer systems is investigated using the photoacoustic spectroscopy. The experimental results are examined in terms of the effective thermal parameters of the composite system determined from a homogeneous material that produces the same physical response under an external perturbation in the detector device. It is shown that the effective thermal conductivity is not symmetric under exchange of the two layers of the composite, i.e. the effective thermal parameters depend upon which layer is illuminated in the photoacoustic experiments. Particular emphasis is given to the characterization of the interface thermal conductivity between the layer system. 相似文献
40.
Polymer integrated reverse symmetry waveguides on porous silicon substrate fabricated by using deep ultraviolet radiation in poly(methyl methacrylate) are presented. The layer sequence and geometry of the waveguide enable an evanescent field extending more than 3 microm into the upper waveguide or analyte layer, enabling various integrated optical devices where large evanescent fields are required. The presented fabrication technique enables the generation of defined regions where the evanescent field is larger than in the rest of the waveguide. This technology can improve the performance of evanescent-wave-based waveguide devices. 相似文献