Abstract: Here, we report on a seed-mediated growth method for the production of goldnanoparticles that have a number (>4) of branches ultimately resembling the shape of sea urchins.These nano-urchins are produced in high yield and exhibit unique optical properties. By altering theamount of gold seeds, HAuCl4 and hydroquinone in the reaction system, we managed to tune thesize of the SGNPs from 40 to 180 nm. Their extinction spectrum shows a shift in the plasmonresonance from 550 to 670 nm. The SERS spectrum of these products prepared were detected andcompared. By optimizing the conditions, SGNPs with uniform morphology, good monodispersityand strong SERS effect were prepared.
Abstract: The influence of electromagnetic wave (EMW) on the acous- tomagnetoelectric (AME)effect is studied theoretically in a quantum well. The expression of the AME field is obtained. Thedependences of the AME field on the temperature of system, the frequency of acoustic wave, thefrequency and intensity of electromagnetic wave and the parameters of a Quantum well are nonlinear.These dependences in the case of QW are different and more complex than in the case of bulksemiconductor. The results are numerically calculated and discussed for an GaAs/AGaAs QW. Thegraph of the dependence of the AME field on the frequency of acoustic wave shows that the changesof external magnetic field drag on the change of value of AME field and the change of the positionof AME field. The value of the AME field in case with the intensity of EMW is much bigger than incase without the intensity of EMW.
Abstract: Vertically aligned anatase TiO2 nanotubes (NTs) were fabricated by anodization of a pureTi foil in ethylene glycol solutions containing different concentrations of deionized (DI) water. Themorphology, elemental composition, and crystallization of TiO2 nanostructures were analyzed byfield emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Ramanspectroscopy, and X-ray spectroscopy (XPS), respectively. The diameter and length of TiO2 NTswere controlled by varying concentrations of DI water. Furthermore, we found that TiO2 NTs in DIwater 12 wt. % was suitable for further applications in UV photodetector due to it has a high volumeto surface area ratio and long tube. TiO2 NTs have a high potential in various applications such as UVphotodetectors, gas sensor, dye sensitized solar cells, and photocatalysts.
Abstract: Indonesia is the second largest country to contribute plastic marine debris in the world. Onthe other hand, Indonesia is facing pavement problem due to various reasons, so it needs to improvethe pavement quality and performance. The addition of plastic waste to the hot mix asphalt (HMA)actually have beneficial effect to improve the pavement quality. Utilization of plastic waste in roadconstruction is conducted by incorporating the plastic waste into the asphalt mixture as an additivewith dry or wet mix process. The objective of this research is to investigate the laboratoryperformance of asphalt mixture using plastic waste addition and its effect on the moisture sensitivity,resistance to deformation and the fatigue life of the asphalt mixture. The addition of plastic waste inHMA will increase the Marshall stability and the resilient modulus of the mixture, improve strippingresistance, moisture sensitivity and also the rutting resistance. Up to a certain plastic content, theaddition of plastic waste will improve the fatigue life and the ravelling resistance of the HMA, on thecontrary excesive addition of the plstic waste will decrease the fatigue life and ravelling resistancecompare to the conventional HMA. The field application is very simillar to conventional HMA,except it requires additional time during dry mix process in the production plant.
Abstract: Acidity is an important influence factor for juice stability. In this study, the effects of acidityon stability of cloudy apple juice were investigated. The stability indexes, such as, turbidity, cloudvalue, cloud stability, and particle size distribution (PSD) were measured at pH 2.0, 2.5, 3.0 and 3.5,along with the untreated juice (pH 3.8) as control group. The results showed that, pH has significanteffects on turbidity, chrome (C*), cloud value, and D50, D90 in PSD of cloudy apple juice. The juicehad a better stabilization at pH 2.5. At this pH condition, the turbidity, cloud value, cloud stability ofjuice was the best. In addition, at pH 2.5, the color of the juice was better, the particles were smaller,and the particle sizes were more uniform. By this study, a theoretical reference could be provided forimproving stability of cloudy apple juice and extending juice shelf life.
Abstract: Tungsten carbide tipped pointed attack picks is widely used in mechanical machinerysuch as roadheaders, continuous miners and longwall shearers. Great efforts have been made toinvestigate the interaction between point attack pick and rock. However, the research on theinvestigation of pick profile on the cutting performance is still a subject little investigated by thescientific community. In this study, the rock fragmentation process is simulated using a 2D discreteelement code, PFC2D. In the simulations, four types of pick tip geometries (mushroom insert, bulletinsert, conical insert, and cap) were employed to investigate the effect of pick profile on the cuttingperformance of point attack picks. The forces acting on the pick and crack propagation process werecontinuously monitored during the simulations. The preliminary results of cutting performance ofthe picks under different cutting scenarios were analyzed.
Abstract: Owing to the fact that conventional Taguchi methods cannot predict the experimentresults of non-level values, this study developed a staged Taguchi neural network prediction modelthat combines the merits of experimental data from the Taguchi method and the learningcapabilities of artificial neural networks. We first used the optimal parameter combinations derivedfrom the L9 orthogonal array experiment data and grey relational analysis as training examples forthe Stage-1 network to construct a preliminary network. Next, we used the crucial factors in theoptimal parameter combinations derived from the grey relational analysis as additional trainingexamples for the Stage-2 network. The results of the staged Taguchi neural network predictionmodel indicate that the prediction performance of the preliminary network in Stage 1 was poor dueto an insufficient number of training examples, while the Stage-2 network produced excellentprediction results.
Abstract: Unique and desirable properties of composites, converted them to one of the favorablematerials in a wide range of applications. At present, various composites are utilized in aircraftinterior such as overhead bins, side walls, ceiling and bulkheads. Since adhesively bondedcomposite joints play crucial role in performance of various engineering components,manufacturing of the joints is an important issue. In the present work, an overview of compositesandwich joints is presented, and different types of defects on this component are outlined. Later,some techniques for detection of defects in the sandwich-structured composites are mentioned.Moreover, as a case study, strength and fracture of sandwich T-joints with and withoutmanufacturing defects are compared. The case study proved the role of manufacturing defects inunfavorable performance of the joints. Results of the case study indicated that it is necessary to usedifferent advanced techniques to investigate and assess performance of sandwich joints prior totheir utilization. Concerning to high applications of sandwich composite joints and limitations ofnondestructive tests, there is still a potential to provide a method or a technique which wouldestimate performance of the joints under different loading conditions.
Abstract: Nowadays, there are several grades of sheet metal used in the automotive industry. Highstrength steel sheets, particularly, have been widely used in order to reduce the weight of vehicles,which is strongly related to their fuel consumption rate. However, it is generally known that thestrength of the sheets, which is relatively higher than that of the conventional carbon steel sheets,results in their low formability. In this work, the limiting drawing ratio and forming behavior of sheetmetal that is conventionally used for automobile parts were evaluated by test using cylindrical cupwith hole. The feasibility to use limiting cup height for comparing formability of sheet metal was alsoincluded in the investigation. The sheet materials used in the experiments are aluminium, cold rolledsteel, high strength steel and advanced high strength steel. The process parameters for this study weredie corner radius and blank holder force. Workpiece materials were prepared with a circular shapeand with a diameter of 80 millimetres. In the center of the circular workpiece, a 12-millimetrediameter hole was drilled to observe the formability of each of the materials. The advantage of usingan initial blank with a hole in the center by the cylindrical cup drawing test is that the cup does notfail from changes of the thickness of material near the punch radius at the bottom of the cup. Thelimiting cup height of the investigated materials were evaluated by test using the cylindrical cup withhole. The results show that the limiting cup height values have a relationship to the limiting drawingratio values of the investigated materials. Testing using cylindrical cup with hole by evaluating thelimiting cup height value is feasible for comparing the formability of sheet metals.