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101.
阻尼材料在飞机炮振减振上的应用 总被引:1,自引:0,他引:1
在飞机炮舱区应用新型阻尼材料LJ5,组成一个全新的阻尼结构系统来吸收由航炮射击时产生的冲击能量,改善其炮击的振动环境.可使炮舱区的动应力下降约30%. 相似文献
103.
104.
Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well solar cells 下载免费PDF全文
Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well(MQW) solar cells are investigated. It is found that due to the reduction of piezoelectric polarization and the enhancement of tunneling transport of photo-generated carriers in MQWs, the external quantum efficiency(EQE) of the solar cells increases in a low energy spectral range(λ 370 nm) when the barrier thickness value decreases from 15 nm to 7.5 nm. But the EQE decreases abruptly when the barrier thickness value decreases down to 3.75 nm. The reasons for these experimental results are analyzed. We are aware that the reduction of depletion width in MQW region, caused by the high resistivity of the p-type GaN layer may be the main reason for the abnormally low EQE value at long wavelengths(λ 370 nm). 相似文献
105.
Chemical mechanical planarization of Ge_2Sb_2Te_5 using IC1010 and Politex reg pads in acidic slurry 下载免费PDF全文
In the paper, chemical mechanical planarization(CMP) of Ge2Sb2Te5(GST) is investigated using IC1010 and Politex reg pads in acidic slurry. For the CMP with blank wafer, it is found that the removal rate(RR) of GST increases with the increase of pressure for both pads, but the RR of GST polished using IC1010 is far more than that of Politex reg. To check the surface defects, GST film is observed with an optical microscope(OM) and scanning electron microscope(SEM). For the CMP with Politex reg, many spots are observed on the surface of the blank wafer with OM, but no obvious spots are observed with SEM. With regard to the patterned wafer, a few stains are observed on the GST cell, but many residues are found on other area with OM. However, from SEM results, a few residues are observed on the GST cell, more dielectric loss is revealed about the trench structure. For the CMP with IC1010, the surface of the polished blank wafer suffers serious scratches found with both OM and SEM, which may result from a low hardness of GST, compared with those of IC1010 and abrasives. With regard to the patterned wafer, it can achieve a clean surface and almost no scratches are observed with OM, which may result from the high-hardness SiO2 film on the surface, not from the soft GST film across the whole wafer. From the SEM results, a clean interface and no residues are observed on the GST surface, and less dielectric loss is revealed. Compared with Politex reg, the patterned wafer can achieve a good performance after CMP using IC1010. 相似文献
106.
Mechanical and thermodynamic properties of the monoclinic and orthorhombic phases of SiC_2N_4 under high pressure from first principles 下载免费PDF全文
First principles calculations are preformed to systematically investigate the electronic structures, elastic and thermodynamic properties of the monoclinic and orthorhombic phases of Si C2N4 under pressure. The calculated structural parameters and elastic moduli are in good agreement with the available theoretical values at zero pressure. The elastic constants of the two phases under pressure are calculated by stress–strain method. It is found that both phases satisfy the mechanical stability criteria within 60 GPa. With the increase of pressure, the degree of the anisotropy decreases rapidly in the monoclinic phase, whereas it remains almost constant in the orthorhombic phase. Furthermore, using the hybrid density-functional theory, the monoclinic and orthorhombic phases are found to be wide band-gap semiconductors with band gaps of about 2.85 e V and 3.21 e V, respectively. The elastic moduli, ductile or brittle behaviors, compressional and shear wave velocities as well as Debye temperatures as a function of pressure in both phases are also investigated in detail. 相似文献
107.
本文采用二乙醇胺(DEA)作为化学吸收剂,通过流程模拟工具Aspen plus对电厂烟道气的CO_2捕集过程进行模拟,分析各个关键参数对系统性能的影响。最后利用MATLAB软件构建了三种模型,对CO_2捕集技术的环境影响进行评价。结论表明:升高吸收溶液温度会减少DEA溶剂损失,降低再沸器热负荷,不过提高溶液温度会消耗额外的能量;当吸收溶液质量分数为0.25时,再沸器消耗的等效功最少;在轮船运输场景下,当泄漏因子取0.05时,其有效排放因子大于参考电厂的排放因子,CCS技术在减缓气候变暖中不会起到作用. 相似文献
108.
气凝胶纳米多孔隔热材料传热计算模型的研究 总被引:2,自引:0,他引:2
本文研究并建立了气凝胶复合隔热材料传热计算模型.针对气凝胶纳米多孔材料的分形结构特征,结合规则交叉球杆结构,提出了气凝胶纳米多孔材料的分形交叉球杆结构模型,并以此结构模型为基础,建立了气凝胶纳米多孔材料热导率分形计算模型,模型中同时考虑了尺寸效应对气相、固相传热方式的影响.对气凝胶中添加的遮光剂、增强纤维等微米典型结构,以Mie辐射散射理论为基础,结合Rossland扩散近似模型,考虑了辐射传热对热量传递的增强作用;同时结合经典的两相系统等效热导率计算公式,获得复合材料的辐射导热耦合热导率计算模型.本文从纳米尺度的气凝胶多孔材料传热模型到微米尺度的气凝胶复合隔热材料传热模型,建立了完整的气凝胶纳米多孔复合隔热材料等效热导率计算模型.模型与多个文献中气凝胶材料热导率实验数值进行比较,获得了满意的结果,验证了模型应用于气凝胶复合隔热材料等效热导率预测计算方面的有效性. 相似文献
109.
A high-power cw end-pumped laser device is demonstrated with a slab crystal of Nd:GdVO4 operating at 1063nm. Diode laser stacks at 880nm are used to pump Nd:GdVO4 into emitting level 4^F3/2. The 149 W output power is presented when the absorbed pump power is 390 W and the optical-to-optieal conversion efficiency is 38.2%. When the output power is 120 W, the M^2 factors are 2.3 in both directions. Additionally, mode overlap inside the resonator is analyzed to explain the beam quality deterioration. 相似文献
110.