排序方式: 共有63条查询结果,搜索用时 15 毫秒
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TBM是隧道开挖的工厂化施工机械,其用电设备多,自动化程度高,技术复杂,对电气设备的安全保护要求较高.介绍其中的几项保护装置,如TJB高压电缆快速接头、高压电缆绝缘及接地线连续保护装置、低压母线绝缘监视装置在TBM上的应用. 相似文献
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A new hybrid method, which combines improved glass-blown technology with wet etching, is reported to fabricate micro wine-glass resonators with high-quality fused silica. The optimum placement is compared to achieve the resonators with good shell shape. The typical shell diameter is about 4mm and its thickness covers from dozens to hundreds of micrometers. The etching rates in corrosion solutions with different ratios and at different thicknesses of hemispherical shells are studied. We also conclude how to precisely control the thickness. The corrosion solutions with different ratios of HF solution to NH4F solution make the spherical shells rougher in different degrees. The best roughness is 0.581 nm in the 1: 8 ratio corrosion solution while the original roughness is 0.537 nm. This fact shows that the resonator remains atomically smooth surface. Based on the glassblowing spherical fused silica structure, the thickness of the resonator is effectively controlled by buffered oxide etch (BOE) technology according to the measured etching rate. The measured resonant frequency of the hemispherical shell at ambient pressure and room temperature is 1.75 kHz of rocking mode which is close to the simulated frequency. Using such a low-cost hybrid approach, we can fabricate high-quality microscale resonators in batch. 相似文献
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研究目的:自主开发设计盾构可编程控制器(PLC)系统,掌握盾构国产化研究的关键技术。
研究方法:针对盾构的结构特点,进行可编程控制器(PLC)的选型;通过对土压平衡盾构的工况、工作流程及功能要求分析,从系统设计、硬件配置、程序编写等方面对PLC控制系统的设计研究进行详细阐述,体现了检修维护方便,扩充灵活,降低造价的设计优点;从土压平衡控制、姿态控制、推进缸速度与压力协调控制等方面,对盾构的主要动作的控制原理进行了说明;并介绍了计算机控制系统对盾构进行参数设置、故障诊断,远程监视、数据采集分析的基本功能。
研究结果:已基本完成PLC控制系统的设计,为实现盾构可编程控制器(PLC)控制系统的国产化打下了基础。
研究结论:对盾构可编程控制器(PLC)系统的设计研究,已列入国家“863”攻关计划,为国产盾构的开发提供了试验参考。 相似文献
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This paper presents a bulk acoustic wave piezoelectric disk resonator based on a special pair of degenerative modes, to detect z-axis angular velocity. A single piezoelectric disk is operated in its appropriate modes in the k Hz frequency range to achieve this function. This design combines the bulk acoustic wave drive/sense mode with lead zirconate titanate resonator which improves device's performance and simplifies its structural complexity. The operation principle of piezoelectric disk resonator is given and validated by finite element method,and the scale factor of piezoelectric disk resonator is 0.977 μV/[(°) · s-1] without any amplification section.The results of impedance analysis for the prototype in the air, which is fabricated on lead zirconate titanate wafer by Micro-Electro-Mechanical System process, show that the resonant frequency of the piezoelectric disk resonator is about 190 k Hz. Moreover, the measured frequency split between drive and sense mode is about290 Hz without any tuning methods. At last, a closed-loop driving and detecting circuit system is designed and its modulation/demodulation method is studied, preliminary experiments show that this device is not sensitive to acceleration, but is sensitive to angular velocity, its performance parameters need follow-up experiments. 相似文献
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本文介绍在隧道施工过程中,采用激光隧道多功能断面检测仪对隧道拱墙衬砌前横断面进行检测的方法;通过对隧道拱墙衬砌前横断面进行检测,保证了二次衬砌厚度,表明了衬砌厚度事前控制的作用和意义。 相似文献
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通过内河航道维护计划各因了变化规律的分析,展示其特点,提出新形势下降低航道维护成本,合理制定维护计划的策略与途径。 相似文献
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