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961.
962.
963.
为研究在雷电冲击下的压敏电阻的性能,利用冲击试验分析了压敏电阻主动能量配合的残压变化,对于各种能量配合方式做出了分析,发现当压敏电阻在暂态过程中吸收的能量过大时,实际损坏形式以雪崩击穿为主.压敏电阻主动能量配合的一组串并联试验结果表明:与单个压敏电阻相比,多个压敏电阻并联可以给出较低的箝位电压,提高泄放暂态过电流的能力,还可以减缓各压敏电阻的性能退化;压敏电阻的串联都是不可取的. 相似文献
964.
Ballast water is a major pathway for the transfer of non-indigenous species in aquatic environments. The objectives of this study were to determine the ability of ozone to reduce the numbers of a spectrum of marine organisms collected from Puget Sound, Washington in replicated mesocosm (280 l) experiments, and estimate the minimum ozone concentrations as measured by total residual oxidant (TRO) required to reduce organism densities. Ozone treatment was effective in removing bacteria, phytoplankton, and mesozooplankton with initial TRO concentrations of 2–5 mg l−1 as Br2. Persistence of TRO resulted in an extended period of toxicity and cumulative mortality. TRO decay allowed bacteria populations to multiply when TRO levels fell below 0.5–1.0 mg l−1 as Br2. Phytoplankton chlorophyll a concentrations were rapidly reduced by ozone treatment and did not increase in any treatments or controls because of lack of light. Overall mesozooplankton viability was rapidly reduced by 90–99% in treatment TRO levels above 1.85 mg l−1 as Br2. Our study outlines novel protocols that can be used for testing different potential ballast water treatment systems in replicated and controlled mesocosm experiments. 相似文献
965.
台湾地震东带是我国地震活动性最高的地区。本文根据灰色系统理论,利用台湾地震东带1947—1990年间的年最大地震构成的时间序列,建立了台湾强震(M_s≥7)的灰色灾变预测模型。其地震发生时间的预测模型为:(?)~(1)(t+1)=(47.74+790.30)e~(0.060786t)-790.30外推结果,本带下一次Ms≥7的地震事件将发生在1996年前后。经检验,本模型的拟合精度属第一级“好”。 相似文献
966.
中国大陆新生代构造应力场的研究 总被引:1,自引:0,他引:1
本文通过断陷盆地的分布特征、震源机制解和地应力测量等方面的资料分析研究,认为新生代以来中国大陆没有统一的构造应力场,或者说现今应力场小于前期应力场;断层活动、地震活动并不意味着应力的不断积累、不断加强,相反是应力的不断释放、不断减弱。 相似文献
967.
968.
以岩体正交异性弹性理论为基础,用X射线法,在安宁河断裂带测区,沿横过和平行断裂带的6条测线,测量了岩体三维宏观残余应力,绘成了宏观残余应力场水平和铅直三维主分量水平分布等值线图、水平和铅直最大剪应力水平分布等值线图及水平主应力线图,研究了此种场对大地震的控制作用。 相似文献
969.
H. Nagase K. Shimizu A. Hiro-oka Y. Tanoue Y. Saitoh 《Soil Dynamics and Earthquake Engineering》2006,26(2-4):209-220
It is widely known that the sensitivity ratio of Ariake marine clay increases, if the clay is leached. Therefore, it is assumed that the mechanical properties of such clay considerably change and the shear strength decreases, if it is subjected to a cyclic load as a disturbance force, like earthquakes. In the present study, dynamic deformation and strength tests, as well as consolidation tests were conducted on Ariake clay that had leached. Static shear tests were also carried out on the clay after it had been subjected to a cyclic load. The stability of man-made earth structures on Ariake clay deposits that had leached during earthquakes was investigated. Undisturbed samples of the clay sedimented in the sea area were used in all the tests. Furthermore, an earthquake-induced residual deformation analysis was also conducted on the basis of the test results described above. Consequently, the following behaviors were observed in the study. (1) When Ariake marine clay was leached, the dynamic strength decreased and the shear modulus after subjecting it to a cyclic load remarkably decreased. (2) The effect of the leaching on the behavior of Ariake clay deposits was considerable during earthquakes. 相似文献
970.
A series of polyaluminum chloride sulfate (PACS) coagulants, which have different SO42–/Al3+ and OH/Al (γ) mole ratio, has been successfully developed using AlCl3·6H2O, Al2(SO4)3·18H2O and Na2CO3 as raw materials. The coagulation performance of PACS for removing natural organic matter (NOM) from surface water was evaluated, and the effect of SO42–/Al3+ mole ratio and γ value in coagulants PACS on DOC and UV254 removal was determined. Furthermore, the influence of pH and dosage of the selected PACS with a SO42–/Al3+ ratio of 0.0664 and a γ value of 2.0, which achieved the best coagulation performance for the removal of DOC and UV254 of all PACS coagulants, on the removal of DOC and UV254 and residual aluminum concentration in treated water was investigated. The results were compared with the ones of polyaluminum chloride (PAC) with γ value of 2.0. The experimental data show that the performance of PACS as a coagulant was highly dependent on SO42–/Al3+ mole ratio and γ value. Both for the selected PACS and for PAC, the best DOC and UV254 removal results were obtained in the range of pH from 5.0 to 8.2 and at the coagulation dose of 5.0 mg/L as Al. Under the optimum coagulation conditions, the selected PACS gave higher DOC and UV254 removal efficiencies, and lower residual aluminum concentrations in the treated water than PAC. The maximum removal of DOC and UV254 for PACS was approximately 88.0% and 93.0%, respectively. At the optimum coagulant dose and pH 6.5, the concentration of residual aluminum in treated water by both selected PACS and PAC can comply with the regulated limits. The major mechanisms of NOM removal by PACS and PAC coagulation involve complexation‐charge‐neutralization‐precipitation. 相似文献