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31.
The effect of ultra-fine fly ash (UFFA), steel slag (SS) and silica fume (SF) on packing density of binary, ternary and quaternary cementitious materials was studied in this paper in terms of minimum water requirement of cement. The influence of mineral admixtures on the relative density of pastes with low water/hinder ratios was analyzed and the relationship between paste density and compressive strength of the corresponding hardened mortars was discussed. The results indicate that the incorporation of mineral admixtures can effectively improve the packing density ofcementitious materials; the increase in packing density of a composite with incorporation of two or three kinds of mineral admixtures is even more obvious than that with only one mineral admixture. Moreover, an optimal amount of mineral admixture imparts to the mixture maximum packing density. The dense packing effect of a mineral admixture can increase the packing density of the resulting cementitious material and also the density of paste with low water/binder ratio, which evidently enhances the compressive strength of the hardened mortar. 相似文献
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<正>High-power vertical-cavity surface-emitting lasers(VCSELs) are processed using a wet thermal-selective oxidation technique.The VCSEL chips are packaged by employing three different bonding methods of silver solder,In-Sn solder,and metalized diamond heat spreader.After packaging,optical output power, wavelength shift,and thermal resistance of the devices are measured and compared in an experiment.The device packaged with a metalized diamond heat spreader shows the best operation characteristics among the three methods.The 200-μm-diameter device bonded with a metalized diamond heat spreader produces a continuous wave optical output power of 0.51 W and a corresponding power density of 1.6 kW/cm~2 at room temperature.The thermal resistance is as low as 10 K/W.The accelerated aging test is also carried out at high temperature under constant current mode.The device operates for more than 1000 h at 70℃,and the total degradation is only about 10%. 相似文献
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A Langmuir-Blodgett (LB) inducing method was firstly used to prepare single layer and multilayer conducting composite PEDOT-PSS film. The film-forming ability of ionization ODA and ODA-SA monolayer spread on PEDOT-PSS nanoparticle sub-phase and the behavior of ODA/PEDOT-PSS assembly particles on pure water were firstly investigated. The results indicated that nanoparticles in the suphase are packed in the ionization monolayer and stable complex Langmuir film is formed at the air/water interface. It has been found that the best film-forming conditions for composite film are as follows:distinct interface was formed between ODA and PEDOT-PSS layer and single layer thickness of PEDOT-PSS was about 23 nm,well accordant to the size of PEDOT-PSS nanoparticles. Different structures were designed to test the conductive ability of these composite films and a variable range hopping (VRH) model was used to explain the film conductive mechanism. The results indicated that a 3D-VRH model explained well the transferring of charge carrier in the multilayer film. 相似文献
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Let E be a cookie-cutter set with dimH E =s. It is known that the Hausdorff s-measure and the packing s-measure of the set E are positive and finite. In this paper, we prove that for a gauge function g the set E has positive and finite Hausdorff g-measure if and only if 0 〈 liminft→0 g(t)/ts 〈 ∞. Also, we prove that for a doubling gauge function g the set E has positive and finite packing g-measure if and only if 0 〈 lim supt→0 g(t)/ts 〈 ∞. 相似文献
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