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Extent of embossing-related residual stress on the magnetic properties evaluated using neutron grating interferometry and single sheet test
摘要： Due to the permanently increasing maximum speed of modern electric machines, the mechanical load on the electrical steel rises. The punched flux barriers of reluctance machines play an increasingly key role in the mechanical design. The weakening of the material and the notching effect can cause local failure due to centrifugal force. In this paper, a method is presented which induces residual stresses by embossing electrical steel laminations, which contribute to the guidance of the magnetic flux and cause a negligible mechanical weakening of the sheet. The aim of this paper is to demonstrate the effectiveness of these embossed flux barriers. This is achieved by using neutron grating interferometry, that allows the density of the magnetic domains to be resolved locally. Furthermore the influence of the embossing is mapped globally by single sheet tests. The finite element analysis of the forming process derives the residual stress distribution which is responsible for the measured magnetic behavior. In order to isolate the influence of the residual stress, non-embossed and stress-relief annealed specimens are used as a reference for both measurement methods.
关键词： Electrical steel,Forming,Electric drives,Neutron grating,Production,Single sheet tester,Mechanical stress,Embossing
更新于2025-09-04 15:30:14
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Improving the cooling of a mechanical oscillator in a dissipative optomechanical system with an optical parametric amplifier
摘要： The ground-state cooling of a macroscopic mechanical oscillator is a crucial prerequisite for implementing the quantum manipulation of the mechanical oscillator. Here we show that a degenerate optical parametric amplifier (OPA) can significantly improve the cooling of the mechanical membrane in the purely dissipative coupling system in the unresolved sideband regime. In the presence of the OPA with a parametric phase π/2, the mechanical membrane can be cooled from room temperature 293 K to 10 mK, a factor of 112 lower than that in the absence of the OPA. If the mechanical oscillator is precooled to 0.1 K, the mechanical membrane can be cooled into the microkelvin regime.
关键词： optical parametric amplifier,dissipative optomechanical system,ground-state cooling,mechanical oscillator
更新于2025-09-04 15:30:14
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APPLICATION OF OPTICAL METHOD IN MEASURING MECHANICAL VIBRATIONS IN A CANTILEVER BEAM
摘要： The pertinent literature discloses a family of optical profile measuring techniques highlighting the moiré methods. The Moiré technique is based on the interference of two superimposed optical grids which produce fringe patterns which can be processed to analyze the DYNAMIC MEASUREMENT IN MATERIALS mechanical behavior. The goal of this research is to experimentally determine the mechanical displacement of a slim cantilever beam by means of Moiré technique with Phase Shift. Photomechanical experimental arrangement included a digital camera, a multimedia projector and a PC. The occurrence of oscillations has been adequately analyzed. The results showed data from which useful information can withdraw, being of great importance to support agricultural machinery projects and development.
关键词： Deformation,Agricultural Machinery,Moiré Technique,Strain,Material Mechanical Behavior Analysis
更新于2025-09-04 15:30:14
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Enhanced etching of tin-doped indium oxide due to surface modification by hydrogen ion injection
摘要： It is known that the etching yield (i.e., sputtering yield) of tin-doped indium oxide (ITO) by hydrocarbon ions (CHx+) is higher than its corresponding physical sputtering yield [H. Li et al., J. Vac. Sci. Technol. A 33, 060606 (2015)]. In this study, the effects of hydrogen in the incident hydrocarbon ion beam on the etching yield of ITO have been examined experimentally and theoretically with the use of a mass-selected ion beam system and by first-principles quantum mechanical (QM) simulation. As in the case of ZnO [H. Li et al., J. Vac. Sci. Technol. A 35, 05C303 (2017)], mass-selected ion beam experiments have shown that the physical sputtering yield of ITO by chemically inert Ne ions increases after a pretreatment of the ITO film by energetic hydrogen ion injection. First-principles QM simulation of the interaction of In2O3 with hydrogen atoms shows that hydrogen atoms embedded in In2O3 readily form hydroxyl (OH) groups and weaken or break In–O bonds around the hydrogen atoms, making the In2O3 film less resistant to physical sputtering. This is consistent with experimental observation of the enhanced etching yields of ITO by CHx+ ions, considering the fact that hydrogen atoms of the incident CHx+ ions are embedded into ITO during the etching process.
关键词： quantum mechanical simulation,sputtering yield,tin-doped indium oxide,hydrogen ion injection,physical sputtering,ITO,etching yield,In2O3,hydrocarbon ions,hydroxyl groups
更新于2025-09-04 15:30:14
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Elusive torque sensed by liquid crystals
摘要： Almost half a century ago, it was predicted that the confinement of quantum fluctuations could induce mechanical rotation — the Casimir torque. This prediction has now been confirmed using liquid crystals. See Letter p.386
关键词： quantum fluctuations,liquid crystals,Casimir torque,mechanical rotation
更新于2025-09-04 15:30:14
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Modeling of 2DEG characteristics of InxAl1?xN/AlN/GaN-Based HEMT Considering Polarization and Quantum Mechanical Effect
摘要： A comprehensive model for 2DEG characteristics of InxAl1?xN/AlN/GaN heterostructure has been presented, taking both polarization and bulk ionized charge into account. Investigations on the 2DEG density and electron distribution across the heterostructure have been carried out using solutions of coupled 1-D Schr?dinger-Poisson equations solved by an improved iterative scheme. The proposed model extends a previous approach allowing for estimating the quantum mechanical effect for a generic InAlN/GaN-based HEMT within the range of the Hartree approximation. A critical AlN thickness (~2.28 nm) is predicted when considering the 2DEG density in dependence on a lattice matched In0.17Al0.83N thickness. The obtained results present in this work provide a guideline for the experimental observation of the subband structure of InAlN/GaN heterostructure and may be used as a design tool for the optimization of that epilayer structure.
关键词： quantum mechanical,polarization effect,InAlN/GaN heterostructure,2DEG density
更新于2025-09-04 15:30:14
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Novel polyimide nanocomposites enhanced by covalent modified graphene nanosheets based on Friedel–Crafts reaction
摘要： We report a new approach to fabricate novel polyimide (PI) nanocomposites using amine-functionalized graphene nanosheets (AGNS). AGNS was successfully prepared by Friedel–Crafts (F–C) reaction and nitroreduction. The PI nanocomposites with outstanding strength and high tribological performance were obtained though in situ polymerization in the presence of different contents of AGNS. The thermal stability, mechanical performance, and the tribological properties of PI/AGNS nanocomposites were significantly enhanced compared with that of pristine PI and PI/graphene nanosheets (GNS) blends, resulting from the strong covalent bonds between AGNS with PI matrix. Particularly, given that the friction coefficient and wear rate were reduced separately by 20.5% and 90.5% under dry sliding condition, the PI/AGNS nanocomposite with 0.5 wt% AGNS manifested the optative friction performance. The combined exclusive friction resistance and mechanical performance were the paramount factors which illustrate the applications of the resultant PI/AGNS nanocomposites in the wear-resistant field or another high-performance material.
关键词： graphene nanosheets,mechanical properties,polyimide nanocomposites,tribological performance,Friedel–Crafts reaction
更新于2025-09-04 15:30:14
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Studies on growth and characterization of (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate: a nonlinear optical material
摘要： Hydrazone compound (E)-N′-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide hemihydrate (DMABHBH) was synthesized and single crystals of DMABHBH were grown by solvent evaporation method at room temperature. Molecular structure of DMABHBH compound was confirmed by 1H and 13C nuclear magnetic resonance techniques. The presence of functional groups was confirmed by Fourier transform infrared and FT Raman spectral analyses. The X-ray crystal structure was elucidated at 173 K by single crystal X-ray diffraction and the results were compared with the corresponding values obtained at 298 K. The compound crystallizes in the chiral monoclinic space group P21. Mechanical stability of the grown crystals was estimated from the Vicker’s microhardness test. Powder second harmonic generation efficiency of DMABHBH is about 1.1 times that of potassium dihydrogen phosphate. DMABHBH is found to show optical limiting behavior at high input light intensities, the third order nonlinear optical absorption coefficient measured using open aperture Z-scan studies, is 0.95 × 10?11 m/W. Anti-bacterial activity was studied using the well and disc diffusion methods.
关键词： X-ray diffraction,Mechanical properties,Nonlinear optical material,Thermal analysis,Antibacterial activity,Hydrazone,Crystal growth
更新于2025-09-04 15:30:14
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The Post Annealing to Control the Number of Layers of 2D MoS2 and SnS2
摘要： We have demonstrated that post annealing could control the layer thickness of 2D MoS2 and SnS2 films transferred on a SiO2/Si substrate by varying the annealing temperature and time. Atomic force microscopy and Raman spectroscopy characterizations revealed that higher annealing temperature and longer treatment time led to thinner films, lower residues and fewer impurities on the surface of 2D materials. In addition, a higher possibility to attain few-layers on both 2D films was achieved using post annealing. The multiple layers of pristine films having the thickness over 15 nm were reduced down to bi-layers after annealing. We observed that the moderate annealing temperature of 450 °C on led to effective layer-thinning compared to the films annealed at 340 °C. The post annealing at 450 °C produced very smooth few-layers (≤4 nm thickness, >1 μm size) of 2D MoS2 and SnS2. However, the 2D films decomposed or disappeared at temperature greater than 650 °C. In addition, process time also affected the number of layers and the sweet spot turned out to be 2 to 3 hours in our experiment.
关键词： Annealing,Mechanical Exfoliation,Layer-Thinning,2D Materials,SnS2,MoS2
更新于2025-09-04 15:30:14
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High-Performance PEDOT:PSS/Hexamethylene Diisocyanate-Functionalized Graphene Oxide Nanocomposites: Preparation and Properties
摘要： Graphene oxide (GO) has emerged as an ideal ?ller to reinforce polymeric matrices owing to its large speci?c surface area, transparency, ?exibility, and very high mechanical strength. Nonetheless, functionalization is required to improve its solubility in common solvents and expand its practical uses. In this work, hexamethylene diisocyanate (HDI)-functionalized GO (HDI-GO) has been used as ?ller of a conductive polymer matrix, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The nanocomposites have been prepared via a simple solution casting method, and have been characterized by scanning electron microscopy (SEM), UV–Vis and Raman spectroscopies, X-ray diffraction (XRD), thermogravimetric analysis (TGA), tensile tests, and four-point probe measurements to get information about how the HDI-GO functionalization degree (FD) and the HDI-GO concentration in the nanocomposite in?uence the ?nal properties. SEM analysis showed a very homogenous dispersion of the HDI-GO nanosheets with the highest FD within the matrix, and the Raman spectra revealed the existence of very strong HDI-GO-PEDOT:PSS interactions. A gradual improvement in thermal stability was found with increasing HDI-GO concentration, with only a small loss in transparency. A reduction in the sheet resistance of PEDOT:PSS was found at low HDI-GO contents, whilst increasing moderately at the highest loading tested. The nanocomposites showed a good combination of stiffness, strength, ductility, and toughness. The optimum balance of properties was attained for samples incorporating 2 and 5 wt % HDI-GO with the highest FD. These solution-processed nanocomposites show considerably improved performance compared to conventional PEDOT:PSS nanocomposites ?lled with raw GO, and are highly suitable for applications in various ?elds, including ?exible electronics, thermoelectric devices, and solar energy applications.
关键词： hexamethylene diisocyanate,PEDOT:PSS,functionalization degree,nanocomposite,optical transmittance,sheet resistance,graphene oxide,mechanical properties
更新于2025-09-04 15:30:14