Materials Literature
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We have numerically investigated lasing dynamics from a twist defect in a cholesteric liquid crystal (CLC) by an auxiliary differential equation finite-difference time-domain (ADE-FDTD) method. As ADEs, the equation of motion of polarization described on the basis of the classical electron oscillator (Lorenz) model an…
In order to study the influence of deionized water and heat treatment on the structure of the crystal, a compositional series of 20Li2O:20SrO:30B2O3:30P2O5 with deionized water and without de-ionized water as a solvent were prepared at 800ᵒC for different sintering time from 7 to 24 h. The crystalline phase and struct…
A novel set-up developed to continuously observe and measure stress driven grain boundary migration is presented. A commercially available tensile/compression SEM unit was utilized for in-situ observations of mechanically loaded samples at elevated temperatures up to 850°C by recording orientation contrast images of b…
Spherical nickel powder of 2–90 μm particle size range was used in order to study the sintering behaviour of the gradual porous structures. According to Stoke’s law, the sedimentation of dispersed particles from suspension starts with the coarser particles and ends with the finest ones. The obtained structures present…
The di-, tetra- and hexamethine merocyaninyes, the derivatives of fluorene, diphenyl 9 H -fluorene-2,7-disulfonate, and bis(2,2,3,3,4,4,5,5-octafluoropentyl) 9 H -fluorene-2,7-disulfonate, as well as the derivatives of the heterocycles of moderate (indolylidene and benzotiazolylidene), weak (benzo[ c,d ]indolylidene a…
Accuracy of cutting simulation model mostly depends on whether its material constitutive equation describes workpiece physical property under cutting state. It is necessary to research on the constitutive properties of cutting material in the high strain state of temperature. In this paper high strength steel GCr15 is…
고분자전해질연료전지(PEMFC)에서 음극 공기에 의한 이온오염은 막전극 합체(MEA)의 성능을 심각하게 열화시킨다. 본 연구에서는 산업단지, 길가, 해변의 공기 중 이온 농도를 측정하였다. 이들 지역에서 $Na^+$ , $K^+$ , $Ca^{2+}$ 와 $Fe^{3+}$ 이온 농도가 비교적 높았다. 가습수로부터 이들 이온이 cathode에 유입되어 MEA 성능에 미치는 영향에 대해 연구하였다. 수돗물을 가습수로 사용해 170시간 운전한 후 MEA 성능이 초기의 11%로 감소하였다. 이들 오염 이온들이 수소이온보다 전해질 막의 슬폰산기와 친화력이 더 강해 전해질 막…
Abstract Investigation of glass-forming alloys on the base of Fe–P system with additions of C, Mn, Cr, Si, and Ni with compositions modeling segregations on grain boundaries in steels revealed the existence of a metastable phase that precipitates at the initial stages of devitrification. This crystalline tetrahedrally…
The chemical vapor deposition (CVD) process has been used to synthesize gallium nitride (GaN) nanostructures using Pt -coated n-type Si (100) as the substrate, and NH 3 gas and Ga 2 O 3 powder as the reaction agents. The surface morphologies of the prepared GaN nanostructures obtained by field emission scanning electr…
Silk fibroin has been widely studied and used in biomedical devices such as sutures because of its excellent mechanical properties, biocompatibility and slow degradability. In this study, Thai silk fibroin was applied as the main material for vascular scaffolds. Surface morphology, water absorption, suture retention s…
Power converters are widely used to control the power energy generated by distributed generators in power grids. The operation of power converters involves monitoring and adjustment of voltage and current by power devices, which are switching rapidly. The rapid switching causes spikes that can result in the false dete…
Thermoelectric effect becomes one of the important elements in sustainable energy due to its capability in green conversion of waste heat into electrical energy. Among various thermoelectric materials, nanostructured-Si0.80Ge0.20 is being widely investigated owing to its efficient thermoelectric effect at high tempera…
니켈에 양극산화법을 적용하여 기존의 선행연구에서 보고되었던 nm 단위의 두께를 극복하고 최대 2.3 ${\mu}m$ 두께의 산화니켈 박막을 제조하였다. 전해질은 에틸렌글리콜을 용매로 사용하였으며 $F^-$ 이온을 공급하기 위해 $NH_4F$ 를 첨가하였다. 전압을 40, 60, 80 V로 변화시키며 최대 12시간까지 양극산화반응을 진행하였으며 시간과 전압을 증가시킴에 따라 산화니켈 박막의 두께도 증가하였다. 그러나 80 V 전압에서는 급격한 산화 작용에 따른 니켈의 파괴가 나타났다. XRD 분석 결과 양극산화에 의해 NiO가 생성되었음을 확인하였다. Nickel o…
The paper presents a finite element (FE) based efficient analysis procedure for very small three-phase synchronous machines. Two FE formulation approaches are proposed to achieve this goal: the magnetostatic and the non-linear transient time stepped formulations. This combination allows us to predict the steady-state…
A 3D grain growth model is developed based on a generalised mean-field approach. It allows the prediction of the growth history of individual grains of a polycrystal during normal grain growth, which has been compared with results from Monte Carlo Potts simulations showing a good agreement. Based on a stochastic grain…
Using three natural graphites with different particle size, 35, 50 and 80 mesh, as raw materials, expandable graphites were prepared by intercalating, water-washing and drying the natural graphites. The products were characterized by X-ray diffraction, Infrared spectroscopy, scanning electron microscope and Raman spec…
Microstructural changes due to isothermal heat treatment in the bent regions of cold folded nickel alloy (Ni200), mild steel, and Titanium (Ti6-4) sheet samples, followed by the EBSD (electron back-scattered diffraction) technique are reported. Large strain gradients that vary from being tensile to compressive exist i…
Cryogenic cooling is a new emerging cooling application in machining processes. Quantitative understanding of the effects of cryogenic cooling on the machining performance is important for continued applications. This study focuses on cryogenic machining of hard-to-machine material, AISI 52100, particularly with an an…
In this work, the core-shell FePt@Fe3O4 nanowires and nanoparticles as a new hard-soft composite magnetic materials were synthetized by reduction of platinum acetyl acetonate and iron pentacarbonyl together in the presence of oleic acid and oleyl amine stabilizers by polyol process. As-synthesized FePt nanowires and n…
The microwave permeability of nitrogen-doped iron films deposited on a flexible lavsan substrate has been experimentally investigated. The measurements were performed with the use of a coaxial transmission line. The coaxial samples were coiled from a flexible film in two different ways: with the deposited layer facing…