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We report on the design and fabrication of a compact two-dimensional xy-positioner for scanning probe microscopes. This positioner uses three piezoelectric bimorphs in flexing or length-change mode by appropriate selection of electrodes and voltage polarities. One end of these bimorphs is fixed to a rectangular metal frame while on each of the free ends two sapphire disks are fixed which can slide against the polished plates of a platform movable in the xy-plane. For moving the platform by one step, the bimorphs are deformed sequentially in one mode and they are brought back to their undeformed state simultaneously. The motion of the positioner has been tested with an optical microscope and a homemade scanning tunneling microscope. 相似文献
44.
Indoline‐Based Molecular Engineering for Optimizing the Performance of Photoactive Thin Films
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Ming Yu Jin Byung‐Man Kim Hyun Sil Jung Jun‐Hyeok Park Deok‐Ho Roh Dong Guk Nam Tae‐Hyuk Kwon Do Hyun Ryu 《Advanced functional materials》2016,26(38):6876-6887
New indoline dyes ( RK‐1 – 4 ) were designed with a planar geometry and high molar extinction coefficient, which provided surprising power conversion efficiency (PCE) with a thin titanium dioxide film in dye‐sensitized solar cells (DSCs). They had a difference in only alkyl chain length. Despite the same molecular structure, the performance of the respective DSCs varied significantly. Investigating the dye adsorption processes and charge transfer kinetics, the alkyl chain length was determined to affect the dye surface coverage as well as the recombination between the injected photoelectrons and the oxidized redox mediators. When applied to the DSCs as a light harvester, RK‐3 with the dodecyl group exhibited the best photocurrent density, consequently achieving the best PCE of 9.1% with a 1.8 μm active and 2.5 μm scattering layer because of the most favorable charge injection. However, when increasing the active layer thickness, overall device performance deteriorated and the charge collection and regeneration played major roles for determining the PCE. Therefore, RK‐2 featuring the highest surface coverage and moderate alkyl chain length obtained the highest PCEs of 8.8% and 7.9% with 3.5 and 5.1 μm active layers, respectively. These results present a promising perspective of organic dye design for thin film DSCs. 相似文献
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Xiaohua Hu Kyoo Sil Choi Xin Sun Yang Ren Yangdong Wang 《Metallurgical and Materials Transactions A》2016,47(12):5733-5749
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Vinay Pratap Singh Anjan Sil R. Jayaganthan 《Transactions of the Indian Institute of Metals》2012,65(1):1-12
An ever increasing demand for high-performance ceramic coatings has made it inevitable for developing techniques with precise
control over the process parameters to enable the fabrication of coatings with the desired microstructure and improved structural
properties. The literature on plasma sprayed nanostructured ceramic coatings such as of Al2O3, Cr2O3, and their composites obtained using reconstituted nano sized ceramic powders has been reviewed in this study. Ceramic coatings
due to their enhanced properties are on the verge of replacing conventional ceramic coatings used for various applications
like automotive systems, boiler components, power generation equipment, chemical process equipment, aircraft engines, pulp
and paper processing equipment, land-based and marine engine components, turbine blades etc. In such cases, the advantage
is greater longevity and reliability for realizing the improved performance of ceramic coatings. It has been observed that
the plasma sprayed nanostructured ceramic coatings show improvement in resistance to wear, erosion, corrosion, and mechanical
properties as compared to their conventional counterparts. This article reviews various aspects concerning the plasma sprayed
ceramic coatings such as (i) the present understanding of formation of plasma-spray coatings and factors affecting them, (ii)
wear performance of nanostructured Al2O3, Cr2O3 and their composite ceramic coatings in comparison to their conventional counterparts, and (iii) mechanisms of wear observed
for these coatings under various conditions of testing. 相似文献
48.
Helen H. Lou Daniel Chen Christopher B. Martin Xianchang Li Kyuen Li Hitesh Vaid Anjan Tula Kumar Kanwar Devesh Singh 《Clean Technologies and Environmental Policy》2012,14(4):737-748
Due to the tremendous costs and difficulties associated with flare measurements, computational fluid dynamics (CFD) simulation could be a viable approach to predict the combustion efficiency as well as VOC/NO x emissions from industrial flaring activities. However, consisting of a large number of reactions and species, most of the detailed kinetic mechanisms for the speciation study of flaring events are too complicated to use in the CFD simulation of industrial-scale flares. A reduced combustion mechanism will lead to improved computational efficiency; however, its fidelity must be validated. This study uses 2D CFD simulations and 1D Chemkin simulations to validate a reduced mechanism developed for the combustion of light hydrocarbons up to C1–C3. This mechanism, consisting of 50 species and 337 reactions, is applicable to C1–C3 hydrocarbons and can be used to predict the combustion efficiency and fate of pollutants released from industrial flares composed of C1–C3 waste gases. In this article, experimental data reported in the literatures have been used to validate the reduced mechanism. The key performance indicators used for comparison are laminar burner-stabilized flames, laminar flame speeds, adiabatic flame temperatures, ignition delay tests, and temperature and concentration profiles of the critical species. The software package CHEMKIN 4.1.1 was used to verify the computational results of laminar flame speeds, adiabatic flame temperatures, and ignition delays. The axial profiles of various critical species are simulated using the commercial CFD software package FLUENT. It is demonstrated that simulation results using this reduced mechanism are in good agreement with reported experimental results. 相似文献
49.
Abstract A multiple-scale perturbation method is developed to study the optical solitons described by a perturbed nonlinear Schrödinger equation. We show that, by properly defining the phase of the soliton pulse, we can obtain corrections to the pulse where a standard soliton perturbation approach fails. A comparison is made with results obtained by other methods as well as with numerical simulations. 相似文献
50.
Anjan Biswas Stephen Johnson Megan Fessak Beatrice Siercke Essaid Zerrad Swapan Konar 《Journal of Modern Optics》2013,60(3):213-217
In this paper an analytical expression for an optical soliton is obtained with the aid of He's semi-inverse variational principle in the presence of third- and fourth-order dispersion as well as inter-modal dispersion. Three laws of nonlinear media are considered in this paper: the Kerr law, the power law and the log law. 相似文献