Advances in Materials Science and Engineering The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Friction Characteristics of Machined Metal with Different Surface Morphologies Thu, 05 Mar 2015 13:19:26 +0000 This study examined the friction characteristics of SAE1045 medium carbon steel processed by milling machining (MM) and abrasive jet machining (AJM). Friction experiments were conducted with variations in load and friction distance. Experimental results show that micro craters produced by AJM help retain lubricant on workpiece surface and thus decrease friction coefficient. Consequently, for the same friction distance, the amount of wear on AJM test specimens is less than that of MM ones. Moreover, increase in load and surface roughness will also result in great wear on the test specimens. Hsin-Min Lee, A-Cheng Wang, and Yan-Cherng Lin Copyright © 2015 Hsin-Min Lee et al. All rights reserved. Characterization on Contacting Surfaces of MEMS Electrostatic Switches by SEM, EDXA, and XPS Thu, 05 Mar 2015 10:55:53 +0000 We focus on the origin and sources of surface contamination and defects causing the failure of MEMS electrostatic switches. The morphology, and elemental and chemical compositions of the contacting surfaces, conducting paths, and other parts of switches have been characterized by means of SEM, EDXA, and XPS in order to understand the difference between the data collected for the devices that had passed the electrical conductivity test and those found to be defective. C, O, Al, Ca, Ti, Cu, and some other impurities were detected on the details of defective switches. Contrariwise, the working switches were found to be clean, at least on the level of EDXA and XPS sensitivity. The main sources of surface contamination and defects were incompletely deleted sacrificial layers, substrate materials, and electrolytes employed for Rh plating of the contacts. The negative influence of foreign microparticles, especially alumina and copper oxides, on the conductivity and porosity of contacts was highlighted. I. A. Afinogenov, I. A. Zeltser, E. B. Trunin, and A. Tolstoguzov Copyright © 2015 I. A. Afinogenov et al. All rights reserved. Shape Designing of Engineering Images Using Rational Spline Interpolation Thu, 05 Mar 2015 06:15:07 +0000 In modern days, engineers encounter a remarkable range of different engineering problems like study of structure, structure properties, and designing of different engineering images, for example, automotive images, aerospace industrial images, architectural designs, shipbuilding, and so forth. This paper purposes an interactive curve scheme for designing engineering images. The purposed scheme furnishes object designing not just in the area of engineering, but it is equally useful for other areas including image processing (IP), Computer Graphics (CG), Computer-Aided Engineering (CAE), Computer-Aided Manufacturing (CAM), and Computer-Aided Design (CAD). As a method, a piecewise rational cubic spline interpolant, with four shape parameters, has been purposed. The method provides effective results together with the effects of derivatives and shape parameters on the shape of the curves in a local and global manner. The spline method, due to its most generalized description, recovers various existing rational spline methods and serves as an alternative to various other methods including v-splines, gamma splines, weighted splines, and beta splines. Muhammad Sarfraz, Munaza Ishaq, and Malik Zawwar Hussain Copyright © 2015 Muhammad Sarfraz et al. All rights reserved. Soft Sensor for Oxide Scales on the Steam Side of Superheater Tubes under Uneven Circumferential Load Tue, 03 Mar 2015 16:47:53 +0000 A soft sensor for oxide scales on the steam side of superheater tubes of utility boiler under uneven circumferential loading is proposed for the first time. First finite volume method is employed to simulate oxide scales growth temperature on the steam side of superheater tube. Then appropriate time and spatial intervals are selected to calculate oxide scales thickness along the circumferential direction. On the basis of the oxide scale thickness, the stress of oxide scales is calculated by the finite element method. At last, the oxide scale thickness and stress sensors are established on support vector machine (SMV) optimized by particle swarm optimization (PSO) with time and circumferential angles as inputs and oxide scale thickness and stress as outputs. Temperature and stress calculation methods are validated by the operation data and experimental data, respectively. The soft sensor is applied to the superheater tubes of some power plant. Results show that the soft sensor can give enough accurate results for oxide scale thickness and stress in reasonable time. The forecasting model provides a convenient way for the research of the oxide scale failure. Qing Wei Li and Gui Huan Yao Copyright © 2015 Qing Wei Li and Gui Huan Yao. All rights reserved. Prediction of Concrete Compressive Strength by Evolutionary Artificial Neural Networks Tue, 03 Mar 2015 15:35:39 +0000 Compressive strength of concrete has been predicted using evolutionary artificial neural networks (EANNs) as a combination of artificial neural network (ANN) and evolutionary search procedures, such as genetic algorithms (GA). In this paper for purpose of constructing models samples of cylindrical concrete parts with different characteristics have been used with 173 experimental data patterns. Water-cement ratio, maximum sand size, amount of gravel, cement, 3/4 sand, 3/8 sand, and coefficient of soft sand parameters were considered as inputs; and using the ANN models, the compressive strength of concrete is calculated. Moreover, using GA, the number of layers and nodes and weights are optimized in ANN models. In order to evaluate the accuracy of the model, the optimized ANN model is compared with the multiple linear regression (MLR) model. The results of simulation verify that the recommended ANN model enjoys more flexibility, capability, and accuracy in predicting the compressive strength of concrete. Mehdi Nikoo, Farshid Torabian Moghadam, and Łukasz Sadowski Copyright © 2015 Mehdi Nikoo et al. All rights reserved. Radiolytic Synthesis of Colloidal Silver Nanoparticles for Antibacterial Wound Dressings Tue, 03 Mar 2015 13:13:08 +0000 Radiolytic synthesis provides a convenient and environmentally-friendly approach to prepare metallic nanoparticles in large scale with narrow size distribution. In this report, colloidal silver nanoparticles (AgNPs) were synthesized by gamma radiation using poly(vinyl alcohol) (PVA) or silk fibroin (SF) as stabilizers and were evaluated for their antibacterial properties. The conversion of metallic silver ions to silver atoms depended on irradiation dose and stabilizer concentration as determined by UV-Vis spectrophotometry and transmission electron microscopy. The uniformly dispersed AgNPs with diameter 32.3 ± 4.40 nm were evaluated as antiseptic agents in films composed of chitosan, SF, and PVA that were processed by irradiation-induced crosslinking. Using disc diffusion assay, the films containing 432 ppm AgNPs could effectively inhibit the growth of both Staphylococcus aureus and Pseudomonas aeruginosa. Therefore, we have demonstrated in our present study that gamma radiation technique can potentially be applied in the mass production of antibacterial wound dressings. Pimpon Uttayarat, Jarurattana Eamsiri, Theeranan Tangthong, and Phiriyatorn Suwanmala Copyright © 2015 Pimpon Uttayarat et al. All rights reserved. Fe-Based Amorphous Composite Coating Prepared by Plasma Remelting Tue, 03 Mar 2015 05:56:33 +0000 Fe-based amorphous composite coating was deposited on the carbon steel substrate by arc spraying and then remelted by a plasma remelting system, in order to improve the mechanical properties of the coatings. The composition, microstructure, and properties of the composite coating were analyzed by means of the metallographic microscope, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and microhardness tester. The results showed that the amorphous composite coatings had more homogeneous and finer microstructure after the plasma remelting. The coating is metallurgically bonded with the substrate, and the hardness of the Fe-based amorphous composite coating is up to 1220 HV. The internal relationship between microhardness and microstructure has been discussed. Zhisheng Li, Zongde Liu, Yongtian Wang, Shunv Liu, Runsen Jiang, and Yang Wang Copyright © 2015 Zhisheng Li et al. All rights reserved. The Effect of Welding Residual Stress for Making Artificial Stress Corrosion Crack in the STS 304 Pipe Mon, 02 Mar 2015 16:09:45 +0000 The stress corrosion crack is one of the fracture phenomena for the major structure components in nuclear power plant. During the operation of a power plant, stress corrosion cracks are initiated and grown especially in dissimilar weldment of primary loop components. In particular, stress corrosion crack usually occurs when the following three factors exist at the same time: susceptible material, corrosive environment, and tensile stress (residual stress included). Thus, residual stress becomes a critical factor for stress corrosion crack when it is difficult to improve the material corrosivity of the components and their environment under operating conditions. In this study, stress corrosion cracks were artificially produced on STS 304 pipe itself by control of welding residual stress. We used the instrumented indentation technique and 3D FEM analysis (using ANSYS 12) to evaluate the residual stress values in the GTAW area. We used the custom-made device for fabricating the stress corrosion crack in the inner STS 304 pipe wall. As the result of both FEM analysis and experiment, the stress corrosion crack was quickly generated and could be reproduced, and it could be controlled by welding residual stress. Jae-Seong Kim, Bo-Young Lee, Woong-Gi Hwang, and Sung-Sik Kang Copyright © 2015 Jae-Seong Kim et al. All rights reserved. Inspection of Wooden Poles in Electrical Power Distribution Networks in Artvin, Turkey Mon, 02 Mar 2015 10:51:40 +0000 According to Trabzon Electricity Distribution Local Directorship’s statistical data, there are 208.000 utility poles in Trabzon, 180.000 utility poles in Rize, and 121.000 utility poles in Artvin. Every year, 17.000 new utility poles are placed in these three cities. The average lifetime of a treated-wood utility pole is typically 40 to 50 years. However, the average lifetime of a treated-wood utility pole in the Eastern Black Sea Region is only about 10–15 years. In this study, the suggestions for enhancing the service life of treated-wood utility poles in Artvin vicinity were listed by determining the deteriorations and degradations using both visual inspection and nondestructive test methods. The results showed that the most important factors affecting the service life of utility poles were the decay due to fungi, insects, inadequate impregnation, and the deep cracks and splits. Engin Derya Gezer, Ali Temiz, and Turan Yüksek Copyright © 2015 Engin Derya Gezer et al. All rights reserved. Preparation of Silver Nanoparticles and Their Industrial and Biomedical Applications: A Comprehensive Review Sun, 01 Mar 2015 14:10:56 +0000 Silver nanoparticles (Ag-NPs) have diverted the attention of the scientific community and industrialist itself due to their wide range of applications in industry for the preparation of consumer products and highly accepted application in biomedical fields (especially their efficacy against microbes, anti-inflammatory effects, and wound healing ability). The governing factor for their potent efficacy against microbes is considered to be the various mechanisms enabling it to prevent microbial proliferation and their infections. Furthermore a number of new techniques have been developed to synthesize Ag-NPs with controlled size and geometry. In this review, various synthetic routes adapted for the preparation of the Ag-NPs, the mechanisms involved in its antimicrobial activity, its importance/application in commercial as well as biomedical fields, and possible application in future have been discussed in detail. Adnan Haider and Inn-Kyu Kang Copyright © 2015 Adnan Haider and Inn-Kyu Kang. All rights reserved. Adhesion Strength of Cellulosic Varnish Coated Wood Species as Function of Their Surface Roughness Sat, 28 Feb 2015 13:31:13 +0000 The objective of this study was to evaluate adhesion strength of four wood species, namely, beech (Fagus orientalis Lipsky), alder (Alnus glutinosa subsp. barbata Yalt.), spruce (Picea orientalis L. Link), and fir (Abies nordmanniana subsp.) coated with cellulosic varnish. Samples were prepared in tangential and radial grain orientations from the above species. Surface quality of the specimens was also measured employing stylus type equipment after samples of all four types of species were sanded with 80- and 180-grit sandpaper prior to coating process. Surface roughness of the specimens sanded with 80-grit sandpaper resulted in significantly higher mean peak-to-valley height () values based on the measurement employing stylus type profilometer. The highest adhesion strength values of 2.39 N/mm2 and 2.03 N/mm2 were found for beech and alder samples, respectively. It appears that overall higher roughness characteristics of the specimens exhibited enhanced adherence between substrate and varnish resulting in higher adhesion strength values. Turgay Ozdemir, Salim Hiziroglu, and Mutlu Kocapınar Copyright © 2015 Turgay Ozdemir et al. All rights reserved. Elastic Modulus Calculation Model of a Soil-Rock Mixture at Normal or Freezing Temperature Based on Micromechanics Approach Sat, 28 Feb 2015 11:02:53 +0000 Considering rock wrapped by soil in the mesoscopic structure of soil-rock mixture at normal temperature, a two-layer embedded model of single inclusion composite material was established to obtain the elastic modulus of soil-rock mixture. Given an interface ice interlayer attached between the soil and rock interface in the mesoscopic structure of soil-rock mixture at freezing temperature, a three-layer embedded model of double inclusion composite material and multistep multiphase micromechanics model was established to obtain the elastic modulus of a frozen soil-rock mixture. With the effect of structure pore with soil-rock mixture at normal temperature taken into consideration, its elastic modulus was calculated with the three-layer embedded model. An experimental comparison found that the predicted effect of the three-layer embedded model on the soil-rock mixture was better than that of the two-layer embedded model. The elastic modulus of soil-rock mixture gradually increased with the increase in rock content regardless of temperature. The increase rate of the elastic modulus of the soil-rock mixture increased quickly especially when the rock content is between 50% and 70%. The elastic modulus of the frozen soil-rock mixture is close to four times higher than that of the soil-rock mixture at a normal temperature. Hao Yang, Zhong Zhou, Xiangcan Wang, and Qifang Zhang Copyright © 2015 Hao Yang et al. All rights reserved. Experimental Investigation of Closed Porosity of Inorganic Solidified Foam Designed to Prevent Coal Fires Sat, 28 Feb 2015 05:55:32 +0000 In order to overcome the deficiency of the existing fire control technology and control coal spontaneous combustion by sealing air leakages in coal mines, inorganic solidified foam (ISF) with high closed porosity was developed. The effect of sodium dodecyl sulfate (SDS) concentration on the porosity of the foams was investigated. The results showed that the optimized closed porosity of the solidified foam was 38.65 wt.% for an SDS concentration of approximately  mol/L. Based on observations of the microstructure of the pore walls after solidification, it was inferred that an equilibrium between the hydration process and the drainage process existed. Therefore, the ISF was improved using three different systems. Gelatin can increase the viscosity of the continuous phase to form a viscoelastic film around the air cells, and the SDS + gelatin system can create a mixed surfactant layer at gas/liquid interfaces. The accelerator (AC) accelerates the hydration process and coagulation of the pore walls before the end of drainage. The mixed SDS + gelatin + AC systems produced an ISF with a total porosity of 79.89% and a closed porosity of 66.89%, which verified the proposed stabilization mechanism. Yi Lu and Botao Qin Copyright © 2015 Yi Lu and Botao Qin. All rights reserved. Stress Monitoring for Anchor Rods System in Subway Tunnel Using FBG Technology Wed, 25 Feb 2015 09:47:35 +0000 This paper presents a model test, used on the tunnels on Xi’an Metro Line 2, as the prototype for evaluating the reinforcing effect of the anchor rod in tunnel construction in loess areas. An independently designed fiber Bragg grating (FBG) sensor was used to monitor the seven strain conditions of the rock bolts during the construction. The result shows that the axial stress of the rock bolt changes after the excavation and increases steadily with the growing pressure in the wall rock. Results additionally show that the anchor rods at the tunnel vault are subjected to a compressive stress that remains relatively constant after the primary and the secondary lining, while those at the spandrel and the corner of the tunnel are subjected to increased tensile stress. This paper demonstrates the feasibility and the superiority of FBG technology for tunnel model tests. Xiaolin Weng, Haohao Ma, and Jun Wang Copyright © 2015 Xiaolin Weng et al. All rights reserved. Optimum Control for Nonlinear Dynamic Radial Deformation of Turbine Casing with Time-Varying LSSVM Wed, 25 Feb 2015 06:39:33 +0000 With the development of the high performance and high reliability of aeroengine, the blade-tip radial running clearance (BTRRC) of high pressure turbine seriously influences the reliability and performance of aeroengine, wherein the radial deformation control of turbine casing has to be concerned in BTRRC design. To improve BTRRC design, the optimum control-based probabilistic optimization of turbine casing radial deformation was implemented using time-varying least square support vector machine (T-LSSVM) by considering nonlinear material properties and dynamic thermal load. First the T-LSSVM method was proposed and its mathematical model was established. And then the nonlinear dynamic optimal control model of casing radial deformation was constructed with T-LSSVM. Thirdly, through the numerical experiments, the T-LSSVM method is demonstrated to be a promising approach in reducing additional design samples and improving computational efficiency with acceptable computational precision. Through the optimum control-based probabilistic optimization for nonlinear dynamic radial turbine casing deformation, the optimum radial deformation is 7.865 × 10−4 m with acceptable reliability degree 0.995 6, which is reduced by 7.86 × 10−5 m relative to that before optimization. These results validate the effectiveness and feasibility of the proposed T-LSSVM method, which provides a useful insight into casing radial deformation, BTRRC control, and the development of gas turbine with high performance and high reliability. Cheng-Wei Fei, Guang-Chen Bai, Wen-Zhong Tang, and Yatsze Choy Copyright © 2015 Cheng-Wei Fei et al. All rights reserved. Influence of Heat Treatment on Biocorrosion and Hemocompatibility of Biodegradable Mg-35Zn-3Ca Alloy Tue, 24 Feb 2015 11:45:24 +0000 Mg-35Zn-3Ca (wt.%) alloy containing nontoxic and biocompatible Zn and Ca as alloying elements was prepared and subjected to heat treatment and artificial aging for different duration of time to reduce its rate of degradation. Solution heat treatment was performed at 310°C while artificial aging was performed at 170°C for 0, 2.5, 5.0, 7.5, and 10.0 h and they were designated as AT0, AT1, AT2, AT3, and AT4, respectively. The finest and most homogenous reticulum was observed on the surface of the AT2 group. The result of immersion test in Hank’s balanced salt solution (HBSS) showed that the corrosion rate of the AT2 group was 2.32 mg/(cm2 day), which was significantly lower as compared to other groups . The hemolysis value was ≤5% in all groups, indicating no toxicity during short-term blood reaction. Jeong-Hui Ji, Il-Song Park, Yu-Kyoung Kim, Sook-Jeong Lee, Tae-Sung Bae, and Min-Ho Lee Copyright © 2015 Jeong-Hui Ji et al. All rights reserved. Feasible Time Evolution Model That Predicts Breakdown in Thin SiO2 Films within Unstressed Interval after Constant-Current Stress Tue, 24 Feb 2015 08:21:09 +0000 This paper proposes a poststress time evolution model for sub-10-nm thick SiO2 films for degradation prediction and the extraction of trap-related parameters. The model is based on the understanding that the degradation in thin SiO2 films continues within the unstressed interval. The phenomenon is captured by an analytical expression that indicates that the time evolution of SiO2 film degradation roughly consists of two stages and that the degradation is more likely to occur if water molecules are present. It is demonstrated that the simple analytical model successfully reproduces measured results. It is also suggested that the degradation process considered here is related to oxygen diffusion in the resistive transition process. Yasuhisa Omura Copyright © 2015 Yasuhisa Omura. All rights reserved. High-Performance Grouting Mortar Based on Mineral Admixtures Mon, 23 Feb 2015 15:02:22 +0000 A study on high-performance grouting mortar is reported. The common mortar was modified by mineral admixtures such as gypsum, bauxite, and alunite. The effects of mineral admixtures on the fluidity, setting time, expansion, strength, and other properties of mortar were evaluated experimentally. The microstructure of the modified mortar was characterized by X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. Moreover, the expansive performance and strength of the grouting mortar were verified by anchor pullout test. The results show that the best conditions for gypsum-bauxite grouting mortar are as follows: a water-to-binder ratio of 0.3, a mineral admixture content of ~15%, and a molar ratio K of 2. The ultimate bearing capacity of the gypsum-bauxite grouting mortar anchor increased by 39.6% compared to the common mortar anchor. The gypsum-bauxite grouting mortar has good fluidity, quick-setting, microexpansion, early strength, and high strength performances. Cong Ma, Yuehu Tan, Erbing Li, Yinsuo Dai, and Meng Yang Copyright © 2015 Cong Ma et al. All rights reserved. Statistical Analysis of the Tensile Strength of Coal Fly Ash Concrete with Fibers Using Central Composite Design Sun, 22 Feb 2015 10:16:12 +0000 The influence of coal fly ash and glass fiber waste on the tensile strength of cement concrete was studied using central composite design. Coal fly ash was used to replace 10% of the cement in the concrete mix. Glass fiber was added to improve the tensile properties of the concrete in different dosages and lengths. In total, 14 mixes were investigated, one only with 10% coal fly ash replacement of cement and the other thirteen were determined by the experimental design. Using analysis of variance, the order of importance of the variables was established for each property (flexural strength and split tensile strength). From the nonlinear response surfaces, it was found that higher values of flexural strength were obtained for fibers longer than 12 mm and at a dosage of 1-2%. For split tensile strength, higher values were obtained for fibers with a length of 19–28 mm and at a dosage of 1–1.5%. Marinela Barbuta, Emanuela Marin, Sorin Mihai Cimpeanu, Gigel Paraschiv, Daniel Lepadatu, and Roxana Dana Bucur Copyright © 2015 Marinela Barbuta et al. All rights reserved. Hydraulic Performance Modifications of a Zeolite Membrane after an Alkaline Treatment: Contribution of Polar and Apolar Surface Tension Components Thu, 19 Feb 2015 13:49:23 +0000 Hydraulic permeability measurements are performed on low cut-off Na-mordenite (MOR-type zeolites) membranes after a mild alkaline treatment. A decrease of the hydraulic permeability is systematically observed. Contact angle measurements are carried out (with three polar liquids) on Na-mordenite films seeded onto alumina plates (flat membranes). A decrease of the contact angles is observed after the alkaline treatment for the three liquids. According to the theory of Lifshitz-van der Waals interactions in condensated state, surface modifications are investigated and a variation of the polar component of the material surface tension is observed. After the alkaline treatment, the electron-donor contribution (mainly due to the two remaining lone electron pairs of the oxygen atoms present in the zeolite extra frameworks) decreases and an increase of the electron-receptor contribution is observed and quantified. The contribution of the polar component to the surface tension is attributed to the presence of surface defaults, which increase the surface hydrophilicity. The estimated modifications of the surface interaction energy between the solvent (water) and the Na-mordenite active layer are in good agreement with the decrease of the hydraulic permeability observed after a mild alkaline treatment. Patrick Dutournié, Ali Said, T. Jean Daou, Jacques Bikaï, and Lionel Limousy Copyright © 2015 Patrick Dutournié et al. All rights reserved. Evaluation of Permanent Deformation of Unmodified and Rubber-Reinforced SMA Asphalt Mixtures Using Dynamic Creep Test Wed, 18 Feb 2015 11:28:38 +0000 This paper presents the evaluation of permanent deformation of rubber-reinforced SMA asphalt mixtures by using dynamic creep test. The effect of trans-polyoctenamer as a cross-linking agent in permanent deformation of rubberized mixtures was also evaluated. Dynamic creep test was conducted at different stress levels (200 kPa, 400 kPa) and temperatures (40°C, 50°C). Permanent deformation parameters such as dynamic creep curve, ultimate strain, and creep strain slope (CSS) were used to analyse the results. Finally, the creep behaviour of the specimens was estimated by the Zhou three-stage creep model. The results show that crumb rubber and trans-polyoctenamer significantly affected the parameters especially at high stress and temperatures. Consistent findings were observed for all permanent deformation parameters. Moreover, based on Zhou model, it was concluded that resistance to permanent deformation was improved by application of crumb rubber and trans-polyoctenamer. Herda Yati Katman, Mohd Rasdan Ibrahim, Mohamed Rehan Karim, Nuha Salim Mashaan, and Suhana Koting Copyright © 2015 Herda Yati Katman et al. All rights reserved. Properties and Microstructures of Sn-Ag-Cu-X Lead-Free Solder Joints in Electronic Packaging Wed, 18 Feb 2015 11:03:57 +0000 SnAgCu solder alloys were considered as one of the most popular lead-free solders because of its good reliability and mechanical properties. However, there are also many problems that need to be solved for the SnAgCu solders, such as high melting point and poor wettability. In order to overcome these shortcomings, and further enhance the properties of SnAgCu solders, many researchers choose to add a series of alloying elements (In, Ti, Fe, Zn, Bi, Ni, Sb, Ga, Al, and rare earth) and nanoparticles to the SnAgCu solders. In this paper, the work of SnAgCu lead-free solders containing alloying elements and nanoparticles was reviewed, and the effects of alloying elements and nanoparticles on the melting temperature, wettability, mechanical properties, hardness properties, microstructures, intermetallic compounds, and whiskers were discussed. Lei Sun and Liang Zhang Copyright © 2015 Lei Sun and Liang Zhang. All rights reserved. Properties of GH4169 Superalloy Characterized by Nonlinear Ultrasonic Waves Tue, 17 Feb 2015 14:20:11 +0000 The nonlinear wave motion equation is solved by the perturbation method. The nonlinear ultrasonic coefficients β and δ are related to the fundamental and harmonic amplitudes. The nonlinear ultrasonic testing system is used to detect received signals during tensile testing and bending fatigue testing of GH4169 superalloy. The results show that the curves of nonlinear ultrasonic parameters as a function of tensile stress or fatigue life are approximately saddle. There are two stages in relationship curves of relative nonlinear coefficients β′ and δ′ versus stress and fatigue life. The relative nonlinear coefficients β′ and δ′ increase with tensile stress when tensile stress is lower than 65.8% of the yield strength, and they decrease with tensile stress when tensile stress is higher than 65.8% of the yield strength. The nonlinear coefficients have the extreme values at 53.3% of fatigue life. For the second order relative nonlinear coefficient β′, there is good agreement between the experimental data and the comprehensive model. For the third order relative nonlinear coefficient δ′, however, the experiment data does not accord with the theoretical model. Hongjuan Yan, Chunguang Xu, Dingguo Xiao, and Haichao Cai Copyright © 2015 Hongjuan Yan et al. All rights reserved. Specimen Test of Large-Heat-Input Fusion Welding Method for Use of SM570TMCP Sun, 15 Feb 2015 08:38:28 +0000 In this research, the large-heat-input welding conditions optimized to use the rear plate and the high-performance steel of SM570TMCP, a new kind of steel suitable for the requirements of prospective customers, are proposed. The goal of this research is to contribute to securing the welding fabrication optimized to use the high-strength steel and rear steel plates in the field of construction industry in the future. This research is judged to contribute to securing the welding fabrication optimized to use the high-strength steel and rear steel plates in the field of construction industry in the future. Dongkyu Lee and Soomi Shin Copyright © 2015 Dongkyu Lee and Soomi Shin. All rights reserved. Enhanced Fatigue Strength of Commercially Pure Ti Processed by Rotary Swaging Thu, 12 Feb 2015 13:19:33 +0000 Fully reversed bending fatigue tests were performed on polished hour-glass specimens of commercially pure titanium grade 1 with three different grain sizes, that were produced by severe plastic deformation (rotary swaging) and subheat treatments, in order to examine the effect of grain size on fatigue. An improvement in fatigue strength was observed, as the polycrystal grain size was refined. The endurance limit stress was shown to depend on the inverse square root of the grain size as described empirically by a type of Hall-Petch relation. The effect of refining grain size on fatigue crack growth is to increase the number of microstructural barriers to the advancing crack and to reduce the slip length ahead of the crack tip, and thereby lower the crack growth rate. It was found that postdeformation annealing above recrystallization temperature could additionally enhance the work-hardening capability and the ductility of the swaged material, which led to a marked reduction in the fatigue notch sensitivity. At the same time, this reduction was accompanied with a pronounced loss in strength. The high cycle fatigue performance was discussed in detail based on microstructure and mechanical properties. Hasan ALkhazraji, Ehab El-Danaf, Manfred Wollmann, and Lothar Wagner Copyright © 2015 Hasan ALkhazraji et al. All rights reserved. Development of Silver Ion Doped Antibacterial Clays and Investigation of Their Antibacterial Activity Thu, 12 Feb 2015 11:27:38 +0000 Kaolinite, sepiolite, and clinoptilolite were used as carriers to develop antibacterial materials. The materials were enriched in sodium by ion exchange. Silver ion exchange by silver nitrate followed by phosphoric acid treatment enabled the controlled release of silver. The antibacterial function of the materials was investigated by halo test and the amount of silver released was investigated by energy dispersive X-ray spectroscopy. The enhanced antibacterial efficiency was obtained by minimizing the silver release which further provided longevity to the material and prevented the health risks posed by excess silver release. Filiz B. Karel, Ali S. Koparal, and Elif Kaynak Copyright © 2015 Filiz B. Karel et al. All rights reserved. Electrocatalytic Study of Paracetamol at a Single-Walled Carbon Nanotube/Nickel Nanocomposite Modified Glassy Carbon Electrode Wed, 11 Feb 2015 14:24:34 +0000 A rapid, simple, and sensitive method for the electrochemical determination of paracetamol was developed. A single-walled carbon nanotube/nickel (SWCNT/Ni) nanocomposite was prepared and immobilized on a glassy carbon electrode (GCE) surface via mechanical attachment. This paper reports the voltammetry study on the effect of paracetamol concentration, scan rate, pH, and temperature at a SWCNT/Ni-modified electrode in the determination of paracetamol. The characterization of the SWCNT/Ni/GCE was performed by cyclic voltammetry. Variable pressure scanning electron microscopy (VPSEM) and energy dispersive X-ray (EDX) spectrometer were used to examine the surface morphology and elemental profile of the modified electrode, respectively. Cyclic voltammetry showed significant enhancement in peak current for the determination of paracetamol at the SWCNT/Ni-modified electrode. A linear calibration curve was obtained for the paracetamol concentration between 0.05 and 0.50 mM. The SWCNT/Ni/GCE displayed a sensitivity of 64 mA M−1 and a detection limit of 1.17 × 10−7 M in paracetamol detection. The proposed electrode can be applied for the determination of paracetamol in real pharmaceutical samples with satisfactory performance. Results indicate that electrodes modified with SWCNT and nickel nanoparticles exhibit better electrocatalytic activity towards paracetamol. Koh Sing Ngai, Wee Tee Tan, Zulkarnain Zainal, Ruzniza Mohd Zawawi, and Joon Ching Juan Copyright © 2015 Koh Sing Ngai et al. All rights reserved. Corrigendum to “Recent Advances in Dye Sensitized Solar Cells” Wed, 11 Feb 2015 09:02:27 +0000 Umer Mehmood, Saleem-ur Rahman, Khalil Harrabi, Ibnelwaleed A. Hussein, and B. V. S. Reddy Copyright © 2015 Umer Mehmood et al. All rights reserved. Design and Micromagnetic Simulation of Fe/L10-FePt/Fe Trilayer for Exchange Coupled Composite Bit Patterned Media at Ultrahigh Areal Density Wed, 11 Feb 2015 07:43:12 +0000 Exchange coupled composite bit patterned media (ECC-BPM) are one candidate to solve the trilemma issues, overcome superparamagnetic limitations, and obtain ultrahigh areal density. In this work, the ECC continuous media and ECC-BPM of Fe/L10-FePt/Fe trilayer schemes are proposed and investigated based on the Landau-Lifshitz-Gilbert equation. The switching field, , of the hard phase in the proposed continuous ECC trilayer media structure is reduced below the maximum write head field at interlayer exchange coupling between hard and soft phases, , higher than 20 pJ/m and its value is lower than that for continuous L10-FePt single layer media and L10-FePt/Fe bilayer. Furthermore, the of the proposed ECC-BPM is lower than the maximum write head field with exchange coupling coefficient between neighboring dots of 5 pJ/m and over 10 pJ/m. Therefore, the proposed ECC-BPM trilayer has the highest potential and is suitable for ultrahigh areal density magnetic recording technology at ultrahigh areal density. The results of this work may be gainful idea for nanopatterning in magnetic media nanotechnology. Warunee Tipcharoen, Arkom Kaewrawang, and Apirat Siritaratiwat Copyright © 2015 Warunee Tipcharoen et al. All rights reserved. Optical Properties of Erbium Zinc Tellurite Glass System Wed, 11 Feb 2015 07:32:48 +0000 Er3+-doped tellurite glasses with molar compositions of xEr2O3-20ZnO-()TeO2 (, 1, 2, 3, and 4 mole%) (EZT) have been successfully synthesized by the melt-quenching method. Density and molar volume have been measured. UV-VIS absorption spectra in the wavelength range of 400–800 nm at room temperature has been measured. The band gap for every composition has been calculated. Photoluminescence spectroscopy in the wavelength range of 400–650 nm and at room temperature has been evaluated. Sidek Hj. Abdul Aziz, R. El-Mallawany, Siti Shawaliza Badaron, Halimah Mohamed Kamari, and Khamirul Amin Matori Copyright © 2015 Sidek Hj. Abdul Aziz et al. All rights reserved.