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陈聃 《工程抗震与加固改造》1986,(2)
宏观震害现象是人们认识地震效应的基础之一。人们通常把宏观震害调查作为地震工程学的一项基础工作。如同结构工程的事故往往导致新的结构理论概念的提出一样,世界上每一次大地震都推动了抗震工作和抗 相似文献
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In this paper, two types of underwater discharges, spark discharge and corona discharge, are investigated by optical diagnosis using a high speed framing camera (HSFC) with the framing time within nanoseconds under the same experimental conditions. In order to capture the photographs of streamer propagation, the influence of the randomicity of the prebreakdown duration is taken into consideration. By increasing the conductivity of water, the randomicity reduces effectively. Experimental results show that, for a spark discharge, the process can be separated into three stages: the generation and propagation of a streamer, the generation and expansion of the discharge channel, and the development and annihilation of the plasma. The streamers do not directly move to the opposite electrode, but form a bush-like figure. With the increase of the number of branches, the velocity of streamer propagation slows down. The trajectory of the initial channel between electrodes is not straight. However, with the channel expanding, its shape transforms into a straight column. For a corona discharge, there are two stages: the generation and propagation of a streamer, and the stagnation and annihilation of the streamer. The initial streamer in a corona discharge is generated later than in a spark discharge. The forms of streamers for both kinds of discharge are similar; however, streamers generated by a corona discharge propagate with a slower velocity and the number of branches is less compared with a spark discharge. When the energy injection stops, the luminescence of plasma inside the discharge channel (spark discharge) or streamers (corona discharge) becomes weaker and weaker, and finally disappears. 相似文献
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本文采用HR4000CG-UV-NIR光纤光谱仪和NI-PCB压力传感器测量了水下等离子体声源脉冲放电光谱和强声波的压力幅值,分析了声与光之间的能量转换关系,并重点观察了不同放电参数对光谱特征的影响。实验结果表明,等离子体声源脉冲放电光谱为连续谱,能量主要集中在500 nm左右的谱段;放电产生的光能量和声波能量相互竞争,具有此消彼长的关系;提高放电电压,减小电极间隙距离可以提高光的辐射强度和半峰值谱宽度;增大电极间隙距离,将使发光能量向远紫外区移动;更换电极材料将明显改变光的谱分布和强度变化。 相似文献
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该数据采集系统是双电源切换装置的一部分,它是基于AT89C51单片机的电压、频率采集设备。可以把采集到的连续的电压信号转换为数字信号和频率(数字)信号。经过微处理器的简单处理而交予数码管实现电压显示和越限报警功能。 相似文献
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陈聃 《工程抗震与加固改造》1979,(1)
美国的地震工程研究与许多其他学科一样,主要在大学进行。有关大学的研究情况大致如下: 1.加州大学伯克利分校(Univ.of California,Berkeley) 克拉夫(R.W.Clough)——结构分析、结构动力学彭津(J.Penzien)——结构动力学、地震运动和结构反应肖普拉(A.K.Chopra)——结构动力学、水坝抗震 相似文献
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