Applied Mechanics and Materials Vols. 84-85

Abstract: The maintenance cost and the extended life of the system under any activities-combination, which represents what kind of activities taken for these chosen components, are analyzed for evaluating the unit-cost life of the system. The optimal activities-combination at each PM stage is decided by using genetic algorithm in maximizing the system unit-cost life. Repeatedly, the PM scheduling is progressed to the next stage until the system's unit-cost life is less than its discarded life. Appropriately a mechatronic system is used as an example to demonstrate the proposed algorithm. This paper uses E-Portfolio based on ICT for mechanical components using genetic algorithms and content analysis to study present application situation of E-portfolio in China, and scientifically forecast the trend of the development of E-Portfolio, which is conducive to grasp the research of E-Portfolio and discover some problems existing in the process.

Abstract: In this paper, the microstructure and hardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy with and without laser shock peening (LSP) were examined and compared. The titanium alloy samples were laser shock peened with different layers at the same power density. The microscopic structure after LSP are tested and analyzed by SEM and TEM. The results indicated that LSP changed the microstructure evidently. After 3 layers laser shock peening, there are nanocrystallization in the LSP zone. The shock wave provided high strain rate deformation and generated high-density dislocations in the material. Multiple severe plastic deformation caused by 3 to 5 LSP layers helped to rearrange the resultant dislocation, to form dislocation networks, leading to the formation of nanocrystallites. On the other hand, the microhardness across the polished surfaces of the titanium materials with and without LSP was measured. It is obvious that the laser shock peening improved the microhardness of the Ti-5Al-2Sn-2Zr-4Mo-4Cr for about 16% at the surface, and the affected depth is about 300 microns from the surface.

Abstract: Many different methods were found to increase the leaching rate by the researchers.In this paper,one of the methods--intensified leaching--was showed that the device for bioleaching was under the condition of static magnetic field.the device were designed according to Helmholtz coils,which can offered the static magnetic field,the leaching will start at the condition of the static magnetic field by the Thiobacillus ferrooxidans ( T. f ).the content of metals in samples were detected by Atomic fluorescence spectrometer after 25 days.Through the experimental analysis, the results showed that under the conditions of pulp density 5%,inoculum 10%,pH 2.0, magnetic induction intensity 3.14mT, the leaching rate of Cu and Fe in chalcopyrite mineral processing solid waste got improved. Especially the copper, the leaching rate raised from15.76% to 18.88%.

Abstract: Lead tungstate, PbWO₄ single crystals co-doped with Mo⁶⁺ and Sb³⁺ ions were grown using the modified Bridgman method. The X-ray powder diffraction, optical transmission, X-ray excited luminescence, photoluminescence, light output and decay time have been investigated. Compared to non-doped PbWO_4, the co-doped PbWO₄:(Mo,Sb) crystals exhibit improved transmittance in the short wavelength region. Luminescence and light output measurements demonstrated that Mo⁶⁺ and Sb³⁺ co-doping could enhance the luminescence of PbWO₄ and increase the light output to about 7.0% of Bi₄Ge₃O₁₂ crystal. Doped Mo⁶⁺ and Sb³⁺ ions in PbWO₄ were tentatively considered to occupy W and Pb sublattice sites mostly. The second excitation peak at 385 nm, which is the second effective excitation for the enhanced blue-green emission in as-grown PbWO₄:(Mo,Sb) crystal, should be related to [MoO₄]^2- group and oxygen vacancy.

Abstract: Polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) hydrogel has been fabricated using freezing-thawing method. The tensile strengthen and swelling properties were tested. The results show that hydrogels mechanical properties are better, reach to about 0.7 MPa, 15% PVA/10% PVP hydrogel is the best, up to 0.82MPa; swelling properties are better, The loss water rate and swelling percentage of hydro gel have similar change trend in the room temperature; When the swelling equilibrium, 10% PVA hydrogel loss water rate is very rapid, the swelling percentage of 15% PVA hydrogel is relatively rapid; The rate of loss water of all hydrogels are more than 70 percent, 10% PVA/3% PVP hydrogel loss water is the fastest, the loss rate is up to 90%; swelling percentage of all hydrogels are over 400%, 15%PVA/8% PVP hydrogel is the highest, close to 600%.

Abstract: Through calcining bauxite, the preparation of active alumina (Al₂O₃) admixture was investigated. The effect of calcination temperature and time on the activity of alumina was studied. Calcination production species and crystalline state were determined by X-ray diffractometer, and the specific surface area referred as an important parameter was also determined. The results showed that the best calcination process of acquiring activated alumina admixture was 500°C1.0h. Alkali-aggregate reaction was inhibited effectively by the active alumina admixture.

Abstract: High efficient white polymer light-emitting diodes (WPLEDs) were fabricated with blue- fluorescent polymers(PFO) and yellow- phosphorescent polymers(PFCz₂-NPYIrm₅) blending as light emitting layer, and a water/alcohol-soluble polymer poly [(9,9-bis(3′-((N,N-dimethyl)-N-ethylammonium)propyl)-2,7-fluorene)-2,7-(9,9-dioctylfluorene) - 4,7-(2,1,3- benzoselenadiazole)]dibromide(PFN) as electron injection layer. The structure of the devices used here is: ITO/PEDOT-PSS(40nm)/PVK(30nm)/PFO: PFCz₂-NPYIrm₅ (60nm)/PFN(20nm)/Ba(4nm)/Al(120nm). When the doping concentration of PFCz₂-NPYIrm5 was 1% and PFN film thickness was about 20nm, the EL emissions from the host and the guests were observed simultaneously and the efficient white light emission with coordinates of (0.34,0.32) was achieved. A maximum external quantum efficiency of 4.8% and luminous efficiency of 6.6cd/A was obtained at 8.5V.

Abstract: In this paper, borate ester had been synthesized by the raw materials glycerol and boric acid. The hydrolytic stability of borate ester was made in-depth study by Karl Fischer trace water analyzer. The result shows that the method was simple and accurate. It not only determined the hydrolytic stability of borate ester, but also quantified the extent of its hydrolysis which had important significance in actual production.

Abstract: SiO₂/TiO₂ photocatalyst was prepared by a sol-gel method applying tetrabutyl titanate as the precursor and cullets as the carrier. The optimal preparing conditions of the SiO₂/TiO₂ composite photocatalyst were optimized. The optimal conditions included 2:1 of the molar ratio of tetraethyl orthosilicate to tetrabutyl titanate, 3 load times, 600°C of calcinations temperature, 3 h of calcination time, 3 mL of the dosage of CH₃COOH and 5:1 of the molar ratio of water to tetrabutyl titanate. The photodegradation percentage of methylene blue could reach 92.26% under the above optimal conditions. Moreover, after three times of the repeated use, the SiO₂/TiO₂ composite photocatalyst still had a relatively high catalytic activity and stability, and the recycle percentage of the photocatalyst could reach 92.80%.

Abstract: The microstructure of talcum powder added with the KH550、KH560 and silane composite coupling agent were studied by atomic force microscope, the modified effect of KH560 coupling agent was the best, which verified through the microstructure analysis and the wetting contact Angle proved law method. The relationship between the dosage of KH560 coupling agent and contact angle was analyzed by the wetting contact Angle proved law method. The optimum dosage of KH560 coupling agent was determined by the experimental results of the viscosity of polishing putty.