Advanced Materials Research Vols. 396-398

Abstract: FeCoNi-expanded graphite (EG) microwave absorption composites were prepared by electroless plating process. Nickel、nickel-cobalt alloy and nickel-cobalt-iron alloy were plated to the expanded graphite, and the elemental composition, structure, magnetic and microwave absorption of these composites were investigated with the use of scanning electron microscopy, X-ray diffraction, energy dispersive spectra, hysteresis loop and electromagnetic parameter analysis. The microwave absorption properties were measured in the frequency range of 2.0-18 GHz. The results show that EG is plated symmetrical magnetic metal or their alloy, it is about 70~150nm thick. The coatings deposited from an electroless bath have the transformation of amorphous phase to crystalline phase after heat treatment 1h at 400°C.The magnetism capability of these composites is enhanced compared with pure EG. The optimum matching is 3mm thick and the maximum reflection coefficient shifts to lower frequency with the increase of thickness. The absorption property of FeCoNi-EG composite after heat treatment 1h at 400°C is the best, and when it is 3mm thick, the maximum theoretical reflection loss is about -28.8dB (the matching frequency is 13.5GHz), and the absorption bandwidth below -10dB is 8GHz. The other adsorption bandwidth below -10dB for plating Ni, Ni-Co, Ni-Fe on the surface of EG were 4.2GHz, 5.2GHz and 6.5GHz, respectively.

Abstract: SnO2@C/graphene nanocomposite was prepared via chemical synthesis method. The electrochemical performance of the SnO2@C/graphene nanocomposite as anode material was measured by galvanostatic charge/discharge cycling. As an anode material for Li ion batteries, the SnO2@C/graphene nanocomposite shows 823mAhg-1 and 732mAhg-1 capacities for the first discharge and charge, respectively, which is more than the theoretical capacity of tin oxide, and has good capacity retention with a capacity of 748mAhg-1 after 30 cycles. These results suggest that SnO2@C/graphene nanocomposite would be a promising anode material for lithium ion battery.

Abstract: Some critical problems of bus body frame during the modal analysis are presented by the principle of Finite Element Method. Then bus body frame is analyzed. After the modal parameters of the frame are obtained, dynamic performance of body frame is discussed to provide reference for the betterment of body frame dynamic performance design.

Abstract: In this paper, (2E,6E)-2,6-Bis(2,3,4-tri-methoxy -benzylidene)cyclohexanone (omitted as tmbcho) (1) was obtained by the reaction of acetic acid, tetrahydrofuran, cyclohexanone and 2,3,4-tri-methoxy-benzaldehyde. Three non-classic hydrogen bonds were observed in the compound. X-ray crystallography shows that the crystal structure is stabilized by intermolecular C-H•••π interactions and it contains plenty of conjugated double bonds. The title compound was characterized by UV-vis and fluorescent spectral studies.

Abstract: Polysulfonyldiphenylene phenylphosphonate (PSPPP) with high melting range of 197 to 205 °C was synthesized via molten polycondensation method. The effect of material ratio, reaction temperature and reaction time of the method was studied, and the preferred reaction conditions were obtained. The target product was characterized by FTIR and thermogravimetric analysis (TGA) was carried out to confirm the thermal stability. The PSPPP synthesized in this paper showed fairly good thermal stability.

Abstract: With the rapid development of computer technology and Internet, all kinds of distant educations based on Internet have been coming out constantly. To reduce the cost of exam and alleviate the burden of teachers, the crew examination system was designed and implemented. This system is an online examination system which integrates computer network technology, database technology and ASP technology. The B/S model was adopted in this system and using ASP visit ODBC accesses database. This system includes two functions: examination system and management system. Test library management, random questions, online testing, automatic scoring, scores query and other functions were achieved. Crew examination system realizes the change from traditional test’s way to the way based on Internet.

Abstract: Neutron imaging by large pinhole is an important part for image acquisition and high-speed transmission in process of fast radiation. In order to get desirable results in experiments, it is necessary to judge performance of various designs qualitatively or quantitatively before experiments. In this paper, we simulate the millimeter-level pinhole imaging system based on Geant4 and analyze the effects of system parameters on imaging. The numerical results can provide theoretical foundation for system designing and simulation data for image analyzing.

Abstract: The hill-climbing has been improved by using the percentage random step and by changing variable values instantly, which is under the condition of an improvement in the objective function having been made by a step forward of a variable in a certain direction, and the improved hill-climbing has been used to solve nonlinear regression problems , and the specific algorithm steps is given, and it has been validated with satisfactory results by using practical examples.

Abstract: A novel unsymmetrical photochromic diarylethene compound bearing a benzofuran unit, 1-[2-methyl-5-formyl-3-thienyl]-2-[2-methyl-3-benzofuran-yl]perfluoroyclopentene(1a) have been synthesized, its photochromic, fluorescence and optical strorage properties were investigated. The compound exhibited obviously photochromism both in hexane and in PMMA film. In hexane, the fluorescence intensity of 1a declined along with the photochromism upon irradiation with 297 nm light. The results showed that the cyclization and cycloreversion process of the compound was determined to be the zeroth/first order reaction. This new photochromic system also exhibited remarkable optical storage character.

Abstract: This paper introduces a novel “direct reaction - hot extrusion” technique for producing high effective, fast modification and high Sr content Al-Sr20 master alloy. It mainly contains four processes: 1) Alloying by a medium-frequency induction furnace with complementary mechanical and electromagnetic stirring; 2) Degassing and deslagging by a rotary degassing method; 3) Casting coarse alloy bars; 4) Producing Al-20Sr master alloy wire by using a hot-extrusion process of large cross-section deformation. Microstructural characterizations revealed that the intermetallic Al4Sr phase in the Al-Sr20 alloy was homogeneously distributed in Al matrix with small size and roundish shapes, which ensured the master alloy wire exhibit advantages including high recovery, good reproducibility, no delitescence of modification, no corrosion on equipments, and good workability with smooth surface, no bubbles, no peeling and no cracking. This Al-Sr20 master alloy has been industrially applied in Al-Si alloys casting in automobiles and motorcycle wheels, etc.