Abstract: This paper presents the progress in the fabrication of highly doped thulium silica fiber. As much as 5.3 wt. % Tm alongside 7.1 wt. % Al (co-dopant) were incorporated into silica preform. The preform was fabricated using the Modified Chemical Vapor Deposition (MCVD)-chelate vapor delivery with soot-dopant stepwise technique. The preform was analyzed for several key properties such as refractive index variation along deposition length, dopants distribution profiles and UV-Vis absorption. The results showed a homogeneous dopants distribution with 4% RSD in the longitudinal refractive index along a 40 cm preform length. The UV-Vis absorption spectrum exhibited a strong absorption peak at 790 nm attributed to Tm 3H4 energy manifold.
Abstract: Cu2SnS3 flower-like nanoparticles consisted of nanoflakes were successfully produced using solvothermal technique at 120°C for 12 h. The precursors used in this process were CuCl2.2H2O, SnCl2.2H2O, and thiourea with dimethyl sulfoxide (DMSO) as a solvent. The results showed that the as-obtained product was triclinic Cu2SnS3 with secondary phases CuS and SnS, and after annealing process, a pure triclinic was obtained. The crystal structure of the obtained samples was investigated by X-ray diffraction which assured the obtained data and the average crystallite size of as-prepared and annealed CTS was found to be 18.42 and 31.6 nm, respectively. Scanning electron microscopy (SEM) showed that the surface morphology has the shape of flower like consisted of nanoflakes. The transmission electron microscope (TEM) displayed the formation of sheets. The band gap was measured using UV-Vis absorption spectroscopy and found that the as-prepared sample has 1.97 eV band gap, which obtained for various phases CuS and SnS. However, this band was changed to 1.26 eV upon the heat treatment at 500°C for 10 minutes. This value of Eg is comparable with the value reported by other literatures.
Abstract: The exhaust dust is an industrial waste that results from the sand molded casting process in the foundry sector. The metal casting industry plays an important role in the reduction of the environmental impact by recycling industrial waste. The idea of manufacturing thermally resistant refractory bricks made of exhaust dust from the foundry industry has motivated managers and researchers. The purpose of this study is to analyze the manufacturing process of refractory bricks made of 10, 20 and 30% exhaust dust and their properties. The dust was analyzed by using the SEM/EDX and XRD techniques. Results show that the specimens used in this study did not meet the required water absorption specifications. However, the 10% and 20% samples presented a desirable porosity. The manufactured bricks were classified as dense, insulating and semi-insulated, respectively. In relation to compression resistance the rupture stress proved to be lower than the level of stress detected in commercial bricks. The temperature test showed that bricks made of exhaust dust cannot be considered refractory for commercial purposes. Although the exhaust dust does have some refractory properties it still cannot be used as raw material in the manufacturing of refractory bricks since it does not meet all the necessary specifications as proposed by this study.
Abstract: The analysis of life cycle energy (LCE) and life cycle carbon (LCC) of building were performed in this study in order to identify the solutions for reducing energy-related carbon emission throughout building life time. The influence factors associated with building envelop materials (wall, insulation, window, window-to-wall ratio) were evaluated. The result showed that operation phase contributed a vast majority (>90%) of LCE and LCC. Only 4% emissions saving could be achieved if autoclaved aerated concrete block, cellulose insulation and triple glazing were implemented with WWR of 0.17. The finding suggested that reducing carbon emission should not only be prioritized through use of high energy efficient materials/technologies but should also integrate energy saving measures since energy demand in tropical country is quite high for cooling building. In addition, increasing a possibility and feasibility for supplying renewable energy should be further investigated importunately.
Abstract: The comparisons of materials that can be used in gas sensors, as well as an analysis of their advantages and disadvantages for this application are carried out in this review article.
Abstract: The Simple Cyclic extrusion compression (SCEC) has been developed for producing Al-1%Cu alloys with fine microstructures and superior properties. SCEC method was applied for only two-passess.It was found that the grain structure was significantly reduced from 1500 μm to 100 μm after two passes of cyclic extrusion. The ultimate tensile strength and elongation to failure of as-cast alloy were 110 MPa and 12 %, respectively. However, the corresponding mechanical properties of the two pass CEC deformed alloy are 275 MPa and 35%, respectively. These findings ensure that a significant improvement in the grain structure has been achieved. In addition, cyclic extrusion deformation increased the surface hardness of the alloy by 50 % after two passes.
Abstract: A technique and supporting software were designed to select optimal conditions for turning of ductile materials. Selection of optimal cutting parameters is based on a number of process requirements, including achieving the favourable chip form.
Abstract: In this study, there are three machining parameters consist of spindle speed, feed rate and depth of cut which were conducted through full factorial with four center points to determine the effect of machining parameters on the surface roughness and verify whether there is curvature in the model for CNC face milling process in an automotive components manufacturer in Thailand. The workpieces used semi-solid die casted ADC12 aluminum alloy crankcase housing which they were performed by the ARES SEIKI model R5630 3-axis CNC vertical machining center and face milling cutter with diameter of 63 millimeters. The surface roughness of face-milled was measured by the surface roughness tester. It was found that the greatest main effect influence to surface roughness was spindle speed, followed by feed rate and depth of cut at significance level of 0.05.
Abstract: ELID ultra-precision grinding mirror surface can achieve nanometer precision. However, after the grinding wheel passivates the abrasive particles in electrolysis, it is easy to scratch the ultra-precision ELID grinding surface into the grinding process. In order to solve this problem, a non-abrasive grain α-Fe bonded grinding wheel is propose, which contains no abrasive particles. After electrolysis, oxide film is formed on the surface of the wheel. In ultra-precision ELID grinding, there is no abrasive particles involved, only the polishing effect of oxide film. There is no need to worry about the scratching of exfoliated abrasive particles that have been machined on ultra-precision ELID surfaces. Thus achieving extremely high surface accuracy.