Applied Mechanics and Materials Vols. 380-384

Abstract: The epoxy resin (ER) and 2,3-epoxypropoxypropytrimethoxysilane (KH-560) were used to prepare alkyd resin (AR) insulating coating. The modified waterborne alkyd resin insulating coating was prepared. The dynamic mechanical properties, thermal properties and electrical properties of the composites were characterized by DMA, TG, et al. The results show that the tertiary amine has a good catalyzing effect for this reaction. When the mass ratio of AR with ER is 1 : 1, the glass transform temperature T_g of material is 64.6 °C. When the content of KH-560 is 5% mass fraction of the alkyd resin, the T_g of composites increase 5.6 °C, the initial degradation temperature increased by 63.78 °C; The r_s and r_v of composites are between 10⁹ ~ 10¹² MΩ; the ε and tanδ is between 0.6553 ~ 0.9975 and 0.0025-0.0036, respectively. The pencil hard degree and the impact strength of coating film are all over 5H and 40N, respectively.

Abstract: Polyhedral oligomeric silsesquioxanes epoxy resin (G-POSS) was prepared from 2,3-glycidyloxypropyl-trimethoxysilane (GTMS) by hydrolytic condensation. Thermal properties and electrical properties and UV-curing gel rate of G-POSS/epoxy resin (ER)/unsaturated polyester (UP) nanocomposites using diphenyliodide hexafluorophosphate (DPI·PF6) as initiator of curing reaction were investigated. The results showed that curing process of G-POSS/ER/UP is the double hybrid free radical/cationic polymerization. The gel rate of all the samples is more than 90%. G-POSS would decrease the electrical resistivity and increases the dielectric constant of the complex curing materials. Thermal stability is increased with the addition of G-POSS.

Abstract: The fabrication of metal parts is the backbone of the modern manufacturing industry. Laser forming is combination of five common technologies: lasers, rapid prototyping (RP), computer-aided design (CAD), computer-aided manufacturing (CAM), and powder metallurgy. The resulting process creates part by focusing an industrial laser beam on the surface of processing work piece to create a molten pool of metal. A small stream of powdered alloy is then injected into the molten pool to build up the part gradually. By moving the laser beam back and forth and tracing out a pattern determined by a CAD, the solid metal part is fabricated line by line, one layer at a time. By this method, a material having a very fine microstructure due to rapid solidification process can be produced. In the present work, a type of direct laser deposition process, called Laser Metal Deposition Shaping (LMDS), has been employed and developed to fabricate metal parts. In the LMDS process, the powder delivery system is an important component to perform the powder transport from powder storage box to powder nozzle, which supplies the raw material for the as-deposited metal parts. Consequently, the stability and precision of powder delivery during LMDS is essential to achieve the metal parts with high quality, so it is critical to evaluate the main factors closely related to the stability and precision of powder delivery. The shielding gas flow and the powder feeding rate were ascertained through experimental measure and formula calculation. The results prove that the suitable shielding gas flow and powder feeding rate can promote the stability and precision of powder delivery, which is the basis for the fabrication of as-deposited metal parts with flying colors.

Abstract: Human α-enolase (ENO1), an evolutionarily conserved and multifunctional protein, is a target self-antigen of rheumatoid arthritis (RA). Rheumatoid arthritis (RA) is genetically associated with MHC class II molecules, such as DRB1*0101, DRB1*0401 and DRB1*0404 allele. Among these DRB1 alleles, DRB1*0401 show the most correlation with RA. However, strong binding ability polypeptide of ENO1 with HLA-DRB1*0401 is still largely unknown. In this study, we used NetMHCII prediction method to predict the strong binding ability polypeptide with HLA-DRB1*0401. Among the 434 predicted fragment peptide, ENO1_129-141: PLYRHIADLAGNS showed strong binding with HLA-DR4 and peptide ENO1_281-293 KSFIKDYPVVSIE is the second candidate peptide. Based on these result, we choosed EON1_129-141 and EON1_281-293 polypeptides to do the molecular modeling, and used the molecular dynamics to optimize the three-dimensional structural model. The molecular dynamics results showed that ENO1_129-141: PLYRHIADLAGNS and ENO1_281-293: KSFIKDYPVVSIE have strong binding ability with HLA-DR4* 0401. In the shared epitope, both ENO1_129-141and ENO1_281-293 have the very near distance 3.15Å and 3.10Å with K71 of the β1 chain. The main-chain conformations of ENO1_129-141 sit more deeply with β1 chain. All together, results indicated that ENO1_129-141 and ENO1_281-293 bind strong with HLA-DR4 and would be potential T cell epitopes of human α-enolase that induced RA.

Abstract: Low-thrust spacecraft orbit transfer optimization problem is studied in this paper, and shooting method is applied to the transfer trajectory optimization for satellites on high eccentric orbit. First, this paper puts forward the gauss perturbation equation of non-singular equinoctial elements. A first order approximated analytical solution of the orbit elements under low-thrust and J₂ perturbation is presented based on perturbation theory. Then, the optimization control model by shooting method is established. Finally, the first order approximated result is compared to the numerical result. A transfer problem is optimized using shooting method. The accuracy and validity of this method is verified.

Abstract: The serious pollution of lead-acid battery and nickel-cadmium battery prompts the Li-ion power battery to become the new alternative battery. As the main body of the Li-ion power battery, the electrode has a great influence on performance of the battery. Thus it is necessary to classify, analyze and research the defects of the battery electrode precisely. Combining with the practical situation of production, in this paper the characteristics of the electrode defects of Li-ion Power battery are described in detail and morphological characteristics are analyzed, which is helpful to the subsequent image processing and the production practice.

Abstract: Li-ion power battery has many advantages, such as high energy, lightweight, long cycle life and so on. It has become a research hotspot in the new energy field. This paper describes the Li-ion power battery coating and drying process which has a significant effect on the performance of Li-ion power battery. According to the market research and business requirements, the project decides to apply heated-wind circulating and shock drying method to dry of the Li-ion power battery electrode. The method has been successfully applied to the production, which has achieved excellent results in energy saving and improving enterprise efficiency.

Abstract: The microstructure evolution and mechanical properties of as-extruded Mg-2.5 Zn-0.5Y Mg alloy were investigated. The grainy intermetallic phases (I-phase and w-phase) observed in the as-cast Mg-2.5Zn-0.5Y alloy distributed homogeneously in the hot extruded alloys. Compared with the cast one, the extruded alloy shows predominant mechanical properties as the result of refined microstructure and the dispersed intermetallic phases formed during hot extrusion. The ultimate tensile strength and the yield tensile strength of the extruded alloy were 354.8 MPa and 305.9MPa respectively.

Abstract: In this paper, electric field shielding effectiveness (SE) of metallic experiment boxwith aperturesilluminated by vertical polarization plane wave has been studied by using modal method of moment technique. Electric field SE has been calculated at three different points on the same plane inside enclosure. The numerical results of the proposed technique are in very good agreement with data available in the literature and experimental results. It is shown that apertures position, aperture number and calculation points have noticeable effect on the electric field SE,four apertures is a better select to improve the shielding ability of an enclosure than one aperture while they have the same area.

Abstract: The internal quality of continuous casting billet mainly refers to the low power structure, center segregation, inner crack and the levels of inclusions. It seriously affects the comprehensive performance of steel and rolling slab of the casting billet center segregation and crack existing. The influence rules of the slab internal quality about the process and the factors of equipment combining with field production data have been discussed in this paper. Then using the improved BP algorithm with added momentum item and the prediction model of central segregation of continuous casting billet base on BP artificial neural network have been built.