使用Cisco路由器模拟测试IPv6隧道技术

IPv4向IPv6的迁移更好的解决了网络容量及网络性能。本文重点论述在Cisco路由器上如何模拟手动隧道及自动隧道两种传输方式,并就其工作原理和实现过程进行了较为详细的分析和概括。同时,对IPv6技术做了一定的预测。     

Effect of SnO–P2O5–MgO glass addition on the ionic conductivity of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

NASICON-type structured compounds Li_1+xM_xTi_2-x(PO₄)₃ (M = Al, Fe, Y, etc.) have captured much attention due to their air stability, wide electrochemical window and high lithium ion conductivity. Especially, Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is a potential solid electrolyte due to its high ionic conductivity. However, its actual density usually has a certain gap with the theoretical density, leading the poor ionic conductivity of LATP. Herein, LATP solid electrolyte with series of SnO–P₂O₅–MgO (SPM, 0.4 wt%, 0.7 wt%, 1.0 wt%, 1.3 wt%) glass addition was successfully synthesized to improve the density and ionic conductivity. The SPM addition change Al/Ti–O bond and P–O bond distances, leading to gradual shrinkage of octahedral AlO₆ and tetrahedral PO₄. The bulk conductivity of the samples increases gradually with SPM glass addition from 0.4 wt% to 1.3 wt%. Both SPM and the second-phase LiTiPO₅, caused by glass addition, are conducive to the improvement of compactness. The relative density of LATP samples increases first from 0 wt% to 0.7 wt%, and then decreases from 0.7 wt% to 1.3 wt% with SPM glass addition. The grain boundary conductivity also changes accordingly. Especially, the highest ionic conductivity of 2.45 × 10^?4 S cm^?1, and a relative density of 96.72% with a low activation energy of 0.34 eV is obtained in LATP with 0.7 wt% SPM. Increasing the density of LATP solid electrolyte is crucial to improve the ionic conductivity of electrolytes and SPM glass addition can promote the development of dense oxide ceramic electrolytes.     

Development of ceramic fiber reinforced glass ceramic sealants for microtubular solid oxide fuel cells

Ceramic fibers in various forms with different fiber sizes are tested to improve the sealing performance of glass ceramic seals for microtubular solid oxide fuel cell applications. In this regard, several sealing pastes are prepared by mixing each ceramic fibers type with glass ceramics at 1.25 wt %. Five layered microtubular anode supported cells are also fabricated by extrusion and dip coating methods to evaluate the sealing performance of the composite sealants. The pastes are applied between the cells and gas manifolds made of Crofer22 APU. The electrochemical and sealing performances at an operating temperature of 800 °C under hydrogen are investigated after the glass forming process. Microstructures of the sealants are also examined by a scanning electron microscope. Experimental investigations reveal that the cells sealed by the pastes with ceramic bulk fiber and ceramic fiber rope gasket show acceptable open circuit potentials close to the theoretical one. These cells can be also pressurized up to around 150 kPa back pressure in the sealing performance tests. On the other hand, the pastes without any filler, with ceramic rope and with ceramic blanket exhibit poor sealing performance due to gas leakage originated from flowing of the main glass ceramic matrix from the joints. Therefore, ceramic bulk fiber and ceramic fiber rope gasket are found to behave as a stopper and can be used to prevent glass ceramics from flowing for microtubular solid oxide fuel cells or similar applications.     

Chemical modification of ethylacetoacetate with ASB in aqueous medium

Ethylacetoacetate (EAA) was mixed with aluminum sec-butoxide (ASB) in aqueous medium. The molar ratio among aluminum sec-butoxide, water, and ethylacetoacetate was 1:200:1. Water diluted nitric acid was added into the mixture until it finally transformed into transparent solution. TEM analysis showed that the surfaces of the colloidal particles with EAA were not as clean as those without EAA, implying the formation of a surface modification layer around the colloidal particle. The IR spectra analysis revealed that with the addition of EAA two characteristic peaks of EAA at 1 731 cm⁻¹ and 1 642 cm⁻¹ associated with C=O stretching vibrations were red-shifted to 1 619 cm⁻¹ and 1 530 cm⁻¹, respectively, indicating the occurrence of the chemical modification reaction among the C=O bonds of EAA and the surface Al-OH bonds of the particles., Furthermore it was confirmed by UV spectra analysis that the UV absorption band of EAA underwent 26 nm of red-shift as a result of the formation of the six-membered ring of the complex between ethylacetoacetate and ASB. It was examined that the chemical modification could be photolyzed by the UV illumination with a wavelength shorter than 270 nm due to the excitation of π − π * transition in the complex. Funded by the Doctoral Fund of University of Jinan (No. XBS0812)     

Modeling heat transfer for phase transition during pressure assisted thawing treatment

The thawing time of ice and freezed Salomon fish during high pressure assisted thawing process was evaluated by computer simulation using a finite element and the results were compared with those under atmospheric pressure. The apparent specific heat method was adopted to treat the release of latent heat. The effects of different factors on the high pressure assisted thawing process were analyzed. The time reductions of different sample dimensions were estimated and the temperature contour of thawing at different conditions was obtained. The results showed that the temperature gap of phase transition was the main factor, which could shorten the thawing time. Moreover, a second order relationship was obtained between pressure and phase transition time.     

粉煤灰在耐酸胶泥中的应用研究

介绍了粉煤灰化学组成及物理性能分析研究，粉煤灰耐酸胶泥的配制、性能试验、施工工艺、经济分析及工程应用情况。     

Local hardness and density variation in glass substrates machined with Spark Assisted Chemical Engraving (SACE)

Spark Assisted Chemical Engraving (SACE) is an unconventional technique for surface micro-machining of non-conductive materials specially glass. SACE offers many advantages for fabrication of microfluidic and Lab on Chip devices. However the exact mechanism of material removal in this technique is not fully understood. Besides, the changes in the properties of the machined sample have not been studied so far. In this letter, the material removed from glass surface is evaluated and the results of nano-indentation test for measurement of the hardness of machined micro-channels surface is reported. Based on the amount of removed mass during machining and results of nano-indentation test on machined samples it is concluded that hardness and density of the machined zones decrease during the process.     

Assessment of a model development for window glass breakage due to fire exposure in a field model

This paper presents a model development for the prediction of window glass breakage and fallout in a field model. Glass breakage is based on the temperature difference and the allowable glass breaking stress; and glass fallout is determined by a preset number of successive breakages. As a validation, generally good agreements are obtained between the numerical predictions and the data from a compartment fire experiment. The predicted glass surface temperature and the adjacent gas temperature are within 10–25% of the test data. For fire sizes of 170, 280 and 390 kW, the time of initial occurrence of glass breakage are shown within reasonable range of the experimental results. For the 680 kW fire case, the model shows an earlier glass fallout time, however, the predicted glass temperature at fallout is around 450 °C and is consistent with previous experiments. Further research to improve the model is discussed such as on radiation modeling and the criteria of glass breakage and fallout.