排序方式: 共有21条查询结果,搜索用时 15 毫秒
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土石坝无粘性粗粒料填筑标准和质量评价探讨 总被引:2,自引:0,他引:2
土石坝无粘性粗粒料填筑标准往往根据经验确定,而施工质量主要是通过碾压参数控制,理论依据不足。最大干密度和已建工程实践证明表面振动器法最大干密度与实际填筑干密度基本相等,可以直接指导设计和施工,据此提出了设计和施工控制标准;从砂砾石料、堆石料等无粘性粗粒料的特性探讨了填筑标准的适用范围,利用干密度与<5 mm粒径含量关系和填筑干密度,可以准确及时地对照填筑标准作出填筑质量评价结果。 相似文献
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This study presents the fabrication and characterization of novel surface-type capacitive humidity sensors using vanadyl phthalocyanine (VOPc) as the active material. The devices, which comprise three different thicknesses,have been fabricated using the thermal evaporation technique. A thin film of VOPc is deposited on thoroughly cleaned glass substrates with pre-pattemed Ag electrodes. The capacitive effect of the samples under humidity has been in-vestigated. Comparison of the samples with different thicknesses shows that the thinnest device seems more sensitive towards humidity. The humidity dependent capacitance properties of the sensor make it beneficial for use in commercial hygrometers. 相似文献
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In this study, Au/Cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole (PEPC) blend thin films. Blend of 2 wt.% of each cellulose and PEPC in benzol were used for the deposition of humidity sensing films. Blend films were deposited on glass substrates with preliminary deposited surface-type gold electrodes. Films of different thicknesses of cellulose and PEPC composite were deposited by drop-casting technique. A change in electrical resistance and capacitance of the fabricated devices were observed with the increase of relative humidity in the range of 0−95% RH. It was observed that the capacitances of the sensors increase, while their resistances decrease with increasing of the relative humidity. The sensors were connected to op-amp square wave oscillators. It was observed that with increase of relative humidity, the oscillator’s frequencies were also increased in the range of 4.2−12.0 kHz for 65 μm thick film sample and 4.1−9.0 kHz for 88 μm thick film sample and for 210 μm sample, the oscillator frequency changed in the range of 4.2−9.0 kHz. Effects of film thickness on the oscillator’s frequency with respect to humidity were also investigated. This polymer humidity sensor controlled oscillator can be used for short-range and long-range remote systems at environmental monitoring and assessment of the humidity level. 相似文献
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面源式红外诱饵弹散布云团仿真研究 总被引:1,自引:1,他引:0
为了研究MJU-50B面源式红外诱饵弹圆柱形薄片在高速运动下发射的云团散布及运动过程,以薄片多体分离过程流场数值仿真为基础,建立了散布过程中薄片个体的刚体运动模型和220种工况下的气动力数据库,数值模拟了0.8马赫下诱饵弹上千片薄片的云团散布过程。仿真计算与试验数据对比分析表明:刚体运动模型能更好地模拟圆柱形薄片云团的散布过程,并提出新的薄片云团分布的特征形态;同时也验证了MJU-50B圆柱式薄片红外诱饵弹能在0.5 s内快速散开,散布面积大,分布均匀,并且能在3.0 s内保持其基本形态。 相似文献
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徐振军 《制冷空调与电力机械》2004,25(6):40-42
据热交换效率的原理,采用试算法编制的表冷器热工计算程序,有效的解决了手工进行表冷器有关计算的不便,并且有利于多种方案的比较. 相似文献