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141.
Determination of actual parameters of manufactured optical coatings (reverse engineering of optical coatings) provides feedback to the design-production chain and thus plays an important role in raising the quality of optical coatings production. In this paper, the reliability of reverse engineering results obtained using different types of experimental data is investigated. Considered experimental data include offline normal incidence transmittance data, offline ellipsometric data, and online transmittance monitoring data recorded during depositions of all coating layers. Experimental data are obtained for special test quarter-wave mirrors with intentional errors in some layers. These mirrors were produced by a well-calibrated magnetron-sputtering process. The intentional errors are several times higher than estimated errors of layer thickness monitoring, and the reliability of their detection is used as a measure of reliability of reverse engineering results. It is demonstrated that the most reliable results are provided by online transmittance data. 相似文献
142.
Mychelle Vianna Pereira Companhoni Jose Ricardo Gomes Matheus Tatiana Lisboa Marcondes Andre Luiz Pinto 《Journal of Materials Science》2012,47(22):7835-7840
Nanostructured materials have been widely studied due to the improvement of their mechanical properties comparing to those of coarse grain materials. The present work intended to analyze the microstructure and microhardness of Zr-2.5Nb processed by high-pressure torsion (HPT), one of the severe plastic deformation techniques. The deformations were carried out at room temperature using a pressure of 5?GPa and 5 anvil turns. Vickers indentation was used to evaluate the microhardness of the samples. Transmission electron microscopy and X-ray diffraction were used to analyze the microstructure. The results showed a significant refinement from the initial microstructure achieving nanometric grain size around 50?nm and phase transformation α?→?ω?+?βI induced by shear. The Vickers microhardness values of the material submitted to HPT technique were significantly higher than those of non-deformed material. Also, HPT procedure resulted in a huge grain refinement of the material and in phase transformation. 相似文献
143.
Makarova TL Shelankov AL Lyubchik SB Serenkov IT Sakharov VI 《Journal of nanoscience and nanotechnology》2012,12(6):5051-5053
Irradiation with helium ions is an effective method for triggering ferromagnetism in graphite. Chemical inertness of helium suggests that local magnetic moment formation is determined solely by the intrinsic carbon defects created during the target damage. Interacting moments are located in two places: in the vicinity of the sample surface and near the point of maximum defect generation. 相似文献
144.
Dmitri A. Molodov Tatiana Gorkaya Christoph Günster Günter Gottstein 《Frontiers of Materials Science in China》2010,4(3):291-305
Recent research on the dynamics of planar grain boundaries is reviewed. Novel measuring techniques developed for in situ observation and recording of magnetically and stress driven grain boundary migration are presented. The results of migration
measurements obtained on bismuth, zinc and aluminum bicrystals are addressed. The experiments revealed that the inclination
of a 〈112〉 tilt boundary in Bi has a very strong influence on its mobility. The migration of planar 〈10$
\bar 1
$
\bar 1
0〉 tilt grain boundaries with different misorientation angles was measured in situ in bicrystals of high purity zinc. The
results proved that there is a pronounced misorientation dependence of grain boundary mobility in the investigated angular
range. The shear stress induced migration of planar symmetric 〈100〉 tilt boundaries in aluminum bicrystals was observed to
be accompanied by a lateral translation of the adjacent grains. The coupling between boundary motion and shearing is not confined
to low angle and some low Σ high angle boundaries, but occurs also for noncoincidence high angle 〈100〉 tilt boundaries. It
has been found that also for stress induced grain boundary motion there is a misorientation dependence of the migration activation
parameters. Lower values of the activation enthalpy and the pre-exponential mobility factor can be associated with boundaries
with tilt angles close to low Σ CSL orientation relationships. 相似文献
145.
Distribution of trans‐resveratrol and its metabolites after acute or sustained administration in mouse heart,brain, and liver 下载免费PDF全文
146.
Nikolay P. Kobelev Mikhail A. Lebyodkin Tatiana A. Lebedkina 《Metallurgical and Materials Transactions A》2017,48(3):965-974
The present paper examines two aspects of the problem of critical conditions of jerky flow in alloys, or the Portevin–Le Chatelier (PLC) effect. Recent development of dynamic strain aging (DSA) models proved their capacity to qualitatively reproduce complex non-monotonic behavior of the critical strain, providing that the parameters of theory are allowed to depend on strain. Experimental measurements of such strain dependences have been realized for the first time and used to revise the predictions of the critical strain and stress relaxation kinetics upon abrupt strain-rate changes. On the other hand, it is usually omitted from consideration that the PLC stress serrations can last very short time in comparison with the characteristic time of stress transients. The development of stress drops was studied with the aid of the acoustic emission (AE) technique. It is shown that such macroscopic instabilities are caused by clustering of AE events which otherwise occur all the time, including the periods of smooth plastic flow. The role of synchronization of dislocation avalanches in the development of abrupt stress serrations and its relationship with the predictions of the local DSA models is discussed. 相似文献
147.
The stationary thermoelastic problem for an orthotopic semi-infinite slab undergoing plane deformation is investigated. The top and bottom faces of the slab are presumed to be free of traction and subject to arbitrary symmetrical distributions of temperature, while the end of the slab is taken to be rigidly fixed and thermally insulated. By using Fourier transforms the heat conduction problem is solved and the corresponding stress problem is reduced to a singular-integral equation. Numerical results are presented for both the temperature and stresses along the fixed end of the slab caused by different prescribed surface temperature distributions. 相似文献
148.
Yunjie Huang Qingfeng Li Tatiana V. Anfimova Erik Christensen Min Yin Jens Oluf Jensen Niels J. Bjerrum Wei Xing 《International Journal of Hydrogen Energy》2013
Indium doped niobium phosphates were prepared from precursors of trivalent indium oxide, pentavalent niobium oxide and phosphoric acid. The obtained materials were characterized by X-ray diffraction, impedance spectroscopy, FT-IR spectroscopy and scanning electron microscopy. It was found that the indium doping promoted formation of the cubic Nb2P4O15 phase instead of the monoclinic Nb5P7O30 phase in the pristine niobium phosphates and enhanced the preservation of OH functional groups in the phosphates. The preserved OH functionalities in the phosphates after the heat treatment at 650 °C contributed to the anhydrous proton conductivity. The Nb0.9In0.1 phosphate exhibited a proton conductivity of five times higher than that of the un-doped analog at 250 °C. The conductivity was stabilized at a level of above 0.02 S cm−1 under dry atmosphere at 250 °C during the stability evaluation for 3 days. 相似文献
149.
Oliver Y. Gutirrez Fernando Prez Gustavo A. Fuentes Xim Bokhimi Tatiana Klimova 《Catalysis Today》2008,130(2-4):292-301
In the present work, with the aim of searching for new, highly effective catalysts for deep HDS, a series of NiMo catalysts with different MoO3 loadings (6–30 wt.%) was prepared using SBA-15 material covered with ZrO2-monolayer as a support. Prepared catalysts were characterized by N2 physisorption, small- and wide-angle XRD, UV–vis diffuse reflectance spectroscopy, temperature-programmed reduction, SEM-EDX and HRTEM, and their catalytic activity was evaluated in the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS). It was observed that ZrO2 incorporation on the SBA-15 surface improves the dispersion of the Ni-promoted oxidic and sulfided Mo species, which were found to be highly dispersed, up to 18 wt.% of MoO3 loading. Further increase in metal charge resulted in the formation of MoO3 crystalline phase and an increase in the stacking degree of the MoS2 particles. All NiMo catalysts supported on ZrO2-modified SBA-15 material showed high activity in HDS of 4,6-DMDBT. The best catalyst having 18 wt.% MoO3 and 4.5 wt.% NiO was almost twice more active than the reference NiMo/γ-Al2O3 catalyst. High activity of NiMo/Zr-SBA-15 catalysts and its evolution with metal loading was related to the morphological characteristics of the MoS2 active phase determined by HRTEM. 相似文献
150.
Amotchkina TV 《Applied optics》2008,47(17):3109-3113
A new empirical expression for estimating minimum achievable residual reflectance of antireflection (AR) coatings is presented. The expression gives an accurate approximation of the minimum residual reflectance for normal- and oblique-incidence AR coatings in the visible and infrared spectral ranges. 相似文献