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1.
In the present work the formation of the interface between polycrystalline silver and thin films of titanium oxide was studied with photoelectron spectroscopy (XPS, UPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Titanium oxide was deposited stepwise on 100 nm thick silver films by reactive magnetron sputtering allowing to study the evolution of the interface formation process. The process involves two steps: formation of thin layer of silver oxide and subsequent growth of the TiO2 film. For better understanding of the silver oxidation process, pure silver films were exposed to a low temperature Ar/O plasma for different time intervals providing a possibility to investigate early stages of the oxide film growth. 相似文献
2.
In interactive theorem proving practice a significant amount of time is spent on unsuccessful proof attempts of wrong conjectures.
An automatic method that reveals them by generating finite counter examples would offer an extremely valuable support for
a proof engineer by saving his time and effort. In practice, such counter examples tend to be small, so usually there is no
need to search for big instances. Most definitions of functions or predicates on infinite structures do not preserve the semantics
if a transition to arbitrary finite substructures is made. We propose constraints which guarantee a correct axiomatization
on finite structures and present an approach which uses the Alloy Analyzer to generate finite instances of theories in the
theorem prover KIV. It is evaluated on the library of basic data types as well as on some challenging case studies in KIV.
The technique is implemented using the Kodkod constraint solver which is a successor of Alloy. 相似文献
3.
A considerable body of literature attests to the significance of internal controls; however, little is known on how the clustering of accounting databases can function as an internal control procedure. To explore this issue further, this paper puts forward a semi-supervised tool that is based on self-organizing map and the IASB XBRL Taxonomy. The paper validates the proposed tool via a series of experiments on an accounting database provided by a shipping company. Empirical results suggest the tool can cluster accounting databases in homogeneous and well-separated clusters that can be interpreted within an accounting context. Further investigations reveal that the tool can compress a large number of similar transactions, and also provide information comparable to that of financial statements. The findings demonstrate that the tool can be applied to verify the processing of accounting transactions as well as to assess the accuracy of financial statements, and thus supplement internal controls. 相似文献
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Santanu Mondal Andriy Durygin Vadym Drozd Jose Belisario Zhe Cheng 《Journal of the American Ceramic Society》2020,103(9):4876-4893
In this research, near fully dense single phase bulk multicomponent transition metal nitride (Nb1/3Ta1/3Ti1/3)N1−δ has been successfully synthesized from mixed commercial powders of NbN, TaN and TiN via reaction flash sintering technique. This was performed with an applied pressure of ~ 35 MPa at 25°C under a constant DC electric field (~24-32 V/cm). The flash event, which is the abrupt increase in current (up to ~ 25.2 A/mm2) and temperature, occurred without preheating. The threshold power dissipation on the sample right before the flash is ~ 0.7 W/mm3. The formation of single phase (Nb1/3Ta1/3Ti1/3)N1−δ random solid solution and its compositional uniformity were confirmed by XRD and EDS, respectively. The effects of ball milling duration and limiting current density on phase formation were studied. Simulation based on Joule heating provides an estimate of the ultimate sample temperature of ~ 1850°C. Vickers hardness of the obtained (Nb1/3Ta1/3Ti1/3)N1−δ is 17.6 ± 0.6 GPa, which is comparable to similarly flash sintered ingredient binary nitrides of TaN and NbN. TGA in air shows that the oxidation resistance of (Nb1/3Ta1/3Ti1/3)N1−δ is better than that of TaN and NbN but inferior to TiN. The study demonstrates that reaction flash sintering can be a highly efficient technique for synthesizing bulk multicomponent ceramics for both material fundamental investigations and application development. 相似文献
7.
The effect of laser surface texturing on transitions in lubrication regimes during unidirectional sliding contact 总被引:13,自引:0,他引:13
Andriy Kovalchenko Oyelayo Ajayi Ali Erdemir George Fenske Izhak Etsion 《Tribology International》2005,38(3):219-225
Laser surface texturing (LST) is an emerging effective method for improving the tribological performance of friction units lubricated with oil. In LST technology, a pulsating laser beam is used to create thousands of arranged microdimples on a surface by a material ablation process. These dimples generate hydrodynamic pressure between oil-lubricated parallel sliding surfaces. The impact of LST on lubricating-regime transitions was investigated in this study. Tribological experiments were conducted with a pin-on-disk apparatus at sliding speeds in the range of 0.015–0.75 m/s and nominal contact pressures that ranged from 0.16 to 1.6 MPa. Two oils with different viscosities (54.8 and 124.7 cSt at 40 °C) were used as lubricants. The test results showed that laser texturing expanded the contact parameters in terms of load and speed for hydrodynamic lubrication, as indicated by friction transitions on the Stribeck curve. The beneficial effects of laser surface texturing are more pronounced at higher speeds and loads and with higher viscosity oil. 相似文献
8.
We use a Mach-Zehdner interferometric technique to study the piezo-optical properties of Cs2HgCl4 crystals at room temperature. All piezo-optical (pi(mn)) and photoelastic (p(in)) tensor constants are obtained. A substantial photoelastic effect and low ultrasonic velocities in these crystals determine a relatively high figure of merit M2 for isotropic diffraction (for a certain geometry of acousto-optical interactions, M2 approximately 110 x 10(-15) s3/kg). The new material may be considered, therefore, a candidate for applications in acousto-optical devices. The dependence of the acoustic walk-off angle on the direction of sound propagation is calculated for the principal crystallographic planes. 相似文献
9.
Abstract— We theoretically modeled the optical plasmon absorption of anisotropic metallic nanoparticles in a liquid‐crystal host medium. Metallic nanorods and spheroids act as pleochroic dopants with virtually unlimited photostability. Calculations predict that full‐color displays based on nanorod orientation driven by the transition from homogeneous to homeotropic LC alignment are feasible. These displays are expected to have large viewing angles without the need for polarizers or LC anchoring surfaces. 相似文献
10.
Adam W. Welch Lauryn L. Baranowski Pawel Zawadzki Clay DeHart Steve Johnston Stephan Lany Colin A. Wolden Andriy Zakutayev 《Progress in Photovoltaics: Research and Applications》2016,24(7):929-939
Development of alternative thin film photovoltaic technologies is an important research topic because of the potential of low‐cost, high‐efficiency solar cells to produce terawatt levels of clean power. However, this development of unexplored yet promising absorbers can be hindered by complications that arise during solar cell fabrication. Here, a high‐throughput combinatorial method is applied to accelerate development of photovoltaic devices, in this case, using the novel CuSbS2 absorber via a newly developed three‐stage self‐regulated growth process to control absorber purity and orientation. Photovoltaic performance of the absorber, using the typical substrate CuInxGa1 − xSe2 (CIGS) device architecture, is explored as a function of absorber quality and thickness using a variety of back contacts. This study yields CuSbS2 device prototypes with ~1% conversion efficiency, suggesting that the optimal CuSbS2 device fabrication parameters and contact selection criteria are quite different than for CIGS, despite the similarity of these two absorbers. The CuSbS2 device efficiency is at present limited by low short‐circuit current because of bulk recombination related to defects, and a small open‐circuit voltage because of a theoretically predicted cliff‐type conduction band offset between CuSbS2 and CdS. Overall, these results illustrate both the potential and limits of combinatorial methods to accelerate the development of thin film photovoltaic devices using novel absorbers. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献