Advanced Materials Research Vols. 452-453

Abstract: The signification of the cleaning of sapphire substrates in precision processing has been presented. The cleaning principles of sapphire substrates have been discussed. The cleaning solution and technology of the sapphire substrates for international production have been presented by cleaning experiments. The size of dust is smaller than 0.13 . The sum of dusts is less than 5 for every substrate. Sapphire substrates can be used in metal organic chemical vapor deposition of GaN without re-cleaning by this method.

Abstract: Due to its inherited complexity, the polymer material parameters’ effect on the scratch resistance is difficult to detect. Using the scratch experimental results of a set of polypropylene (PP), the Self-Organizing Map (SOM) method, an artificial neural network algorithm, was adopted to study the effect of various material parameters on polymer scratch. Especially suitable for the analysis of high-dimensional data with nonlinear statistical relationships, SOM method helps to find out the influence of different material parameters on scratch behavior. This information can be used to estimate the possible performance of polymeric materials to certain extent without extra scratch experimental work. It also helps researchers to decide which group of properties should be paid more attention when studying the coupling effect of material parameters on polymer scratch resistance.

Abstract: By analyzing the transmitionce and heat rate of insulating antireflection films conposed by refractive-index adjustable SiO2 layer and TiO2 layers, the optimum combination of antireflection films of BIPV is obtained. The absorption rate at the ultraviolet part that wavelenght excessive inadequate 400nm of the optimized fils is 99.9%, which are directly designed on the surface of the low iron tempered glass panel of BIPV, and in the wavelength range 400nm-800nm, the visible light transmitionce rate is up to 99.5%, and the heat that wavelenght excessive 800nm is reflected of 20%. For the multilayer heat insulation films are composed with the same kind of material while with different refractive indexes, there is no projecting stress between these films and no constraints during the production process of different films for the possible low cost heat insulating of BIPV.

Abstract: According to MD simulation results, pressing depth between two bonding materials will affect bonding strength. Alloy material (Al0.9Cu0.1) had void defect phenomenon in low bonding speed condition because the increasing chance of atom migration which will result in low bonding strength. High tensile speed causes material fracture phenomena earlier happen than low speed. Material stress in low speed is smaller than in high speed. Fracture morphology of material is different in different tensile speed. In low speed condition, material can be stretched thinner than in high speed condition. Material in high temperature has greater kinetic energy than low temperature; therefore, material in high temperature has better formability and behaves larger tensile strain than low temperature. For pure aluminum, when temperature raises to 900K which is close to melting point (933K), its crystal structure is no longer belongs to F.C.C. structure, so bonding strength is weaker than low temperature. Large size material has larger contact area than small size material; therefore, the tensile force and tensile strength of the former are larger than the latter. The order of bonding strength for these three materials is: binary alloy > pure copper > pure aluminum.

Abstract: The nonlinearities, induced by structural looseness or wear/fatigue of components, are good indicators of the health condition of a machine or structure. However, most existing condition monitoring techniques were initially designed for dealing with linear systems, thus unable to account for these scenarios properly. A few available nonlinear techniques are tried in condition monitoring. However, they are more or less limited owing to either intensive computation or unsatisfactory sensitivity to incipient abnormalities. In view of this, a new fractal analysis-based condition monitoring technique is researched in this paper. Firstly, a few number of fractal analysis methods with efficient computing algorithms are investigated in order to find an ideal one for condition monitoring application. Subsequently, a detailed investigation was conducted to verify the favored method and understand its instantaneous properties, robust performance against noise, and sensitivity to the abnormalities. Finally, following discussing the window width used in practical calculation, the condition monitoring technique developed based on the favored fractal analysis method is validated experimentally. Experiments show that the proposed technique does provide an efficient and successful nonlinear tool for machine operation condition and structural health condition assessment.

Abstract: In this paper an artificial neural network (ANN) is used to correlate experimentally determined heat transfer rate of non-continuous helical baffle heat exchangers. First the heat exchangers with three helical angles were experimentally investigated under different inlet volumetric flow rate and temperature. The commonly implemented radial-basis function (RBF) neural network is applied to develop a prediction model based on the limited experimental data. Compared with correlations, the RBF network exhibits superiority in accuracy. The satisfactory results suggest the RBF network might be used to predict the thermal performance of shell-and-tube heat exchangers with helical baffles.

Abstract: Ferritic stainless steel is an economical stainless steel which doesn’t contain nickel or a little nickel. It has the broad prospects of application. By using 21% Cr ferritic stainless steel as test material, the paper analyses the microstructure of the joint. The different welding parameters have the different effect on the depth, the solidification form and the microstructure.

Abstract: At present, in the cycloid rotational indexing processing back taper technique, machining requirements were achieved mainly through the method of using cycloid cluster to approach the involute, so that the processing efficiency was hindered. To solve this problem, this paper proposes an improved method that reduces the number of cycloids to enhance the processing efficiency. Firstly, the best approximating cycloid of the involute tooth profile is figured out. Then, the involute is segmented into sections, and the best approximating cycloid on each section is calculated. Each cycloid approaches the involute section to a maximum extent until completing the entire involute approximation. Finally, the simulative processing is carried out. The result demonstrates that the number of cycloids is one third of the previous and the machining time saves about 64%. This indicates that the improved method is feasible to machine back taper.

Abstract: To better understand the bristle behavior and leakage performance in brush seals, a Computational Fluid Dynamics (CFD) model has been developed, in which the brush is treated as an anisotropic porous region with nonlinear resistance coefficients. With the calculated pressure distribution and the cantilever beam theory, aerodynamic and contact forces on bristles are calculated utilizing the Finite Element Method; and bristle deflections in the axial direction and in the orthogonal plane are obtained. Subsequently their influences on friction force and torque are evaluated. Computed different kinds of low hysteresis brush seals, discuss the effect of size parameters of front plate and back plate on low hysteresis brush seals.

Abstract: We investigated quantum annealing (QA) via the transverse interaction with XY-type anisotropy for a ground state problem for a small composed of 4 S=1/2 quantum spins interacting with anti-ferromagnetic interactions with each other. By solving the Schrodinger equation for the QA system, we found that a preferable solution can be derived by tuning the XY-type anisotropy of the kinetic term among multiple candidates of the QA system. Similar behavior was suggested from the static property obtained by the spin wave theory established in statistical physics. In addition, we clarified that the ground state of the target system can be obtained by the QA starting from an initial state including excited states of the kinetic term, if the interval of time of the QA is set to be large to some extent.