Applied Mechanics and Materials Vols. 716-717

Abstract: An organic acid antifreeze coolant was developed in this paper which consisted mainly of deionized water, organic acid, pyrrole compound, alkali and dye. Glycol, nitrite, chromate, inorganic phosphate and other harmful additives were not contained in this formulation. The coolant overcomes the disadvantages in environmental protection, heat transfer and cost of the current technology which uses the ethylene glycol as antifreeze. The coolant has good low temperature protection, thermal conductivity and corrosion protection performance. Further more, the coolant has the advantages of simple preparation, good storage stability and a promising prospects.

Abstract: In order to study the growth process and morphology of dendrite directly, a phase field model of binary alloy was established. In this model the order parameter equation was coupled with the temperature field and the solute field. The growing processes and morphology of dendrite were simulated by using this phase field model. Through analyzing the results, we discussed the effects of anisotropic strength and temperature gradient on dendrite morphology. The results shows that with the increasing of anisotropic strength, the dendrite growth rate of the dendrite will increase and the secondary branches appear more clearly. Besides, the temperature gradient has influence on the appearance of secondary arms during the dendrite growing. With the increase of temperature gradient, the size of secondary dendrite arms increase.

Abstract: Secondary electron emission (SEE) processes play an essential role in spacecraft surface charging. It is difficult to study SEE of insulator whose surface cumulates charges by incident electron bombardment because of poor conductivity. This paper investigated the theoretical process of generation, transfer and escape of secondary electrons, and finally the paper presented a mathematical model to calculate the secondary electron emission. We also have improved measurement system to measure total SEE coefficient from dielectric with 1-5 keV electron irradiation which is perfectly fit to mathematical model, and the SEE coefficient with different surface charging is investigated. The results indicate the SEE coefficient decreases with positive charging and increase with negative charging of dielectric surface.

Abstract: Biomass is an important renewable energy and making hydrogen-rich syngas from biomass is promising. Dual fluidized bed gasification technology can increase hydrogen content in the syngas. Moreover, steam gasification of biomass coupled with lime-based CO2 capture in a dual fluidized bed can further improve the syngas quality . This paper established a dual fluidized bed gasification model using Aspen plus,in order to explore the effect of different gasification temperatures and steam to biomass ratios on hydrogen content in syngas, providing a theoretical basis for the optimization of operating parameters and process.

Abstract: “Red Globe” table grapes were packaged at four temperature conditions: -1C、-0.5C、0C and 4C. Pathogens carrier rate of grape flesh, grape pedicel, grape peduncle and disease incidence rate were measured at 0, 15, 30, 45, 60, 75 and 90 days. The result revealed that-0.5C was the best storage condition of “Red Globe” table grape, from perspective of pathogens carrier rate of grape flesh, grape pedicel, grape peduncle and disease incidence rate. There was a positive correlation between disease incidence rate and pathogens carrier rate of grape parts. This study is to provide a theoretical basis for reducing the loss red grapes.

Abstract: UV photoresponse of n-ZnO/p-Silicon nanowire (SiNW) photodiodes is investigated by varying post-treatment conditions. Based on spectral responsivity measurement, the responsivity of our photodiodes decreases with increasing the post-annealing temperature in vacuum atmosphere, and the biggest responsivity reaches to as high as ~42 A/W under a reverse bias of 2V near 390 nm when the post-annealing temperature is at 100 °C. And the responsivity is higher when our devices are annealed in vacuum atmosphere than in oxygen atmosphere. We think that the higher responsitivity may be due to the smaller grain size and more oxygen-vacancy-related defects in ZnO film deposited at lower temperature. These results may benefit potential applications of n-ZnO/p-SiNW photodetectors in ultraviolet region.

Abstract: Aiming at the question of predicting mechanics properties of long fiber reinforced metal matrix composites (MMC) shafts, two periodical arrangement of fiber, namely Square array and Hexagonal array are considered in structure,based on the Micro-mechanics Finite Element Method (FEM), six representative volume element models (RVE) are presented, calculating the Macro-mechanics properties parameters of the material. The results are compared with that of three frequently Micro-mechanics models.On the basis, taking a low pressure turbine as study object,then the results calculated of specified RVE model will be used in modal analysis of shafts with MMC,the numerical simulation method is used to calculate natural frequency, analyzing the influence of layers angles, thicknesses, sequences on modal and natural frequency.

Abstract: Cobalt ferrite (CoFe₂O₄) thin films have been prepared on Si (001) substrates, with different calcined temperatures (Tcal=400°C~800°C). The films structure was studied by X-ray diffraction (XRD) and their surface was examined by scanning electron microscopy (SEM). The magnetic properties were measured with a vibrating sample magnetometer (VSM). For low calcined temperatures, the films presented a mixture of a CoFe₂O₄ phase, with the cubic spinel structure, and cobalt and iron antiferromagnet oxides with CoO and FeO stoichiometries. As the calcined temperature increased, the CoO and FeO relative content strongly decreased, so that for Tcal=800°Cthe films were composed mainly by polycrystalline CoFe₂O₄. The magnetic hysteresis cycles measured in the films were horizontally shifted due to an exchange coupling field originated by the presence of the antiferromagnetic phases.

Abstract: One Bis-Boc-L-alanine-1,8-naphthyridine ligand containing amino acid by amido bond named 2,7-Bis-Boc-L-alanine-1,8-naphthyridine (L1) was synthesized and characterized. And there absorption and fluorescence spectra in methanol is presented. Then, the comprehensive study of spectroscopic properties upon titration of L1 with heavy metal ions as ion source in CH₃OH was investigated. It shows compound L1 can use as a fluorescent probe for heavy metal ions like Cr³⁺.

Abstract: The electronic absorption spectra of four meso-phenyl and 3,5-diaryl substituted BODIPY dyes, A to D, were investigated theoretically using the time-dependent density functional theory (TD-DFT) B3LYP method. The dependence of spectra with the molecular and electronic structures was investigated on the basis 6-31+G*, 6-31G and 6-31G* in different solvents. The UV-Vis spectra were in good accordance with the experimental values. The maximum wavelengths of BODIPYs arose from S₀→S₁ transition which stemmed from HOMO to LUMO (π_{bodipy core}→π_{bodipy core}*).