Advanced Materials Research Vols. 217-218

Abstract: A new kind of the micron-sized flaky silver-coated copper powder was prepared by electroless silver plating in this paper. Its plating structures were characterized by XRD, SEM and EDS. And a new kind of the electromagnetic shielding composite coatings containing 60 wt% the micron-sized flaky silver-coated copper powders and 40 wt% epoxy resin was prepared. Its electromagnetic shielding properties were analyzed by coaxial transmission line equipment. The study results show the micron-sized flaky silver-coated copper powders are composed of 91.35 wt% Cu and 8.65 wt% Ag and have high width-thickness ratio and crystal structure characteristics. In the frequency range of 0.3-1000 MHz, the shielding effectiveness of the coatings is up to 70.15-77.46 dB and increased an average of 22.18 dB compared with the coatings containing 60 wt% micron-sized flaky copper powders when the coating layer thickness is 300 μm. It is seen that the electroless silver plating method effectively improves the inoxidizability, conductivity and electromagnetic shielding properties of copper powders.

Abstract: A new multi-objective scheduling method based on the GA is proposed to the job-shop scheduling problem (JSP) constrained by machines, workers. Function objectives of the proposed method are to minimize the completion time, the maximum load of machines and the total expense of machines and workers. Firstly, the mathematical model is constructed. Then, on the basis of the mathematical model, the genetic algorithm (GA) based on Pareto is applied, and an optimal or suboptimal scheduling plan can be obtained. The optimal solutions are not unique due to the multi-objective of JSP. Finally, a scheduling example is employed to illustrate that the proposed method could solve multi-objective job shop scheduling problem effectively.

Abstract: In this paper, mixed mode stress intensity factor (SIF) solutions are computed for inclined surface cracks in finite-thickness plates. The S-version finite element method (S-FEM), which is an adaptive method and multi-scale computing method, are employed in the analyses. When S-FEM is applied to solve the fracture problem, local mesh model including cracks can be built independently from the global mesh model for modeling overall structure. The local model is superposed on the g- lobal one. Therefore, it is easy to introduce cracks in an existing mesh model. The influences of inc- lination angles, crack shape and plate thickness on the mixed mode fracture solution were investiga- ted. The solutions presented can be used to assess fail/safe conditions and fatigue crack growth for the three-dimensional cracks studied.

Abstract: In order to realize less time consuming and on-line image classification for steel strip surface defects, an improved multiclass support vector machine (SVM) was proposed. The SVM used a novel algorithm and only constructed (k-1) two-class SVMs where K is the number of classes. In the testing phase, to identify the surface defects it used a new unidirectional acyclic graph which had internal (k-1) nodes and k leaves. Its testing time is less than traditional multiclass SVM method. The experiment results shows that this method is simple and less time consuming while preserving generalization ability and recognition accuracy toward steel strip surface defects.

Abstract: Study on new absorption materials is important to the sound stealth of targets underwater. The simpler formulae of calculating multiple-layer absorption model is educed with transferring matrix. By numerical simulating, the relation between model’s acoustic characteristics and material parameters of each layer is provided.The study shows that a better performance is acquired when material Young’s modulus changed dynamically with frequency by a certain rule. On these basises, simulation contrast of the absorbing performances between styrene-butadiene rubber(SBR) and Spray Poiyurea Elastomer(SPUA) was carried out. The simulating result and the experiment provided that SPUA has good performance.

Abstract: The influence of the rice husks powder (RHP) content and its particle size distribution on the composite’s tensile strength, fracturing elongation ratio, flexural strength and flexural elastic modulus has been investigated. Respective water absorption and thermal properties of PP composites incorporated with different proportion of RHP have also been analyzed. The microstructure of fractured surfaces was further observed in scanning electron microscopy (SEM). The results showed that the composites with RHP of 245 μm have higher mechanical properties. The tensile strength and fracturing elongation ratio decrease with the increase of RHP content, and reach peak values in 30% RHP content. Water absorption and volume expansion ratio of the composite increase with the increasing of RHP content. Flexural strength and flexural modulus decrease after water absorption. When PHR content is low, the RHP particles are well distributed and the interface of RHP and PP is smooth. When PHR content is higher, the RHP particles tend to agglomerate, leading to poorer interface and lower mechanical properties, the composite failed with brittle fracture.

Abstract: At present day pipe mill engineers have to deal with challenging technological problems of heavy-wall and high strength line pipe manufacturing. Numerical analysis of welded large-diameter pipe manufacturing stages is the most efficient way to solve these problems. Corresponding computational technologies and applied software was developed at Physical & Technical Center. Numerical structural analysis of steel plates at various stages of line pipe manufacturing is performed by the finite element method accounting for geometric and material nonlinearities. The only thing to be done by the engineer in such analysis is to specify required input parameters. All the further process is software-controlled. The discrepancy between the numerical analysis results and measured data in the overwhelming majority cases did not exceed 1%.

Abstract: The molecule weight and distribution of molecule weight of a kind of medium temperature phenol formaldehyde resin（MTPF）was detected through Liquid Chromatogram-mass spectrum instrument（LC-MS）．The result showed that the distribution scope of molecule weight of the MTPF during the initial stage was approximately 200-400，and the degree of polymerization of the MTPF molecule was 2-4，At the same time，the MTPF during initial stage still has a certain amount of medium outcome hydroxymethyl phenol which was formed through the addition reaction between phenol and formaldehyde．The detection result，from the MTPF during initial stage through ZEN3600 nanometer grain analysis instrument， proved that the grain size of the MTPF during initial stage was about 80-180nm，and the distribution of the grain size presented a normal one that the grain size 96-130nm was about 67%．

Abstract: In the development of new large megawatt size wind turbines, aerodynamic and structural reserch is interesting and important for study wind turbine performace and boost the development of wind power. In this paper, the aerodynamic and aeroelastic characteristic of blades is investigated and presented based on Blade Element Momentum and Hamilton theory. Then the flexible characteristics of balde is researched with the aerodynamic and aeroelastic model of the rotor. The flapwise and edgewise displacements, velocities and accelerations of blade tip are simulated and plotted to validate the model which is presented in this paper. The results have very important significance to investigate the vibration and fatigue lifetime of the wind turbine blades.

Abstract: A hierarchical zeolite was synthesized by self-assembly of ZSM-5 nano-crystals colloid and polystyrene spheres coated with cationic poly (diallyldimethylammonium chloride). The colloidial ZSM-5 nano-crystals were first bound onto the polyelectrolyte-modified PS by electrostatic attraction, followed by centrifugation to form PS/ZSM-5 close-packed composite. After being dried and calcined to remove the organic components, the hierarchical zeolite was obtained. The X-ray diffraction, scanning electron microscopy, transition electron microscopy and N2 adsorp-tion-desorption techniques were employed to characterize the hierarchical zeolite. The results showed that the material prepared by this method was well crystallized and possessed uniform ma-cropores interconnected in three dimensions through windows. Furthermore, the hierarchical zeolite was rather mechanically stable.