排序方式: 共有62条查询结果,搜索用时 62 毫秒
31.
Yuanxiang Zhou Hanghai Hu Xu Xu Jifeng Cui Yichao Yuan Zhenyu Li Yuan Chen Deming Yu Qiong Nie Xidong Liang Zhicheng Guan 《Journal of Electrostatics》2009,67(2-3):311-315
Bird-caused outages are more common and widespread than generally believed, and greatly threaten the safety of transmission lines. However, few reports are concerned with laboratory research of bird-caused faulting, especially in the case of long air gap insulators. This paper carried out experimental and simulation work on bird streamer flashover of 220 kV insulators. It was found that the radial distance from the insulator axis shows great influence on the bird streamer flashover. Significant is that we also found a high-risk region of bird streamer flashover which can be restricted in an elliptical region located at the center of 220 kV insulator string, the major and minor axes being 500 mm and 250 mm. The processes of flashover due to bird streamer are discussed in detail. Simulation work further demonstrates the existence of the elliptical region of high flashover risk, which is of significance for transmission line protection. 相似文献
32.
Most plasma reactors are designed for research purposes and they are less appropriate for industry. To facilitate the engineering of an industrial reactor, an effective approach based only on the calculated Paschen curve, the simulation of the electric field and the breakdown reduced field is proposed. The results show that the experimental Paschen curve is different from the theoretical one; consequently the recalculation of the electric parameters is discussed. The experimental voltage/Current characteristic is used to identify the abnormal glow discharge regime and also to correlate the visual aspect of the discharge with its regimes. 相似文献
33.
Enhancement of the electron fluxes in the inner radiation belt,which is induced by the powerful North West Cape(NWC) very-low-frequency(VLF) transmitter,have been observed and analyzed by several research groups.However,all of the previous publications have focused on NWC-induced 100-keV electrons only,based on observations from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions(DEMETER) and the Geostationary Operational Environmental Satellite(GOES) satellites.Here,we present flux enhancements with 30-100-keV electrons related to NWC transmitter for the first time,which were observed by the GOES satellite at night.Similar to the 100-300-keV precipitated-electron behavior,the low energy 30-100-keV electron precipitation is primarily located east of the transmitter.However,the latter does not drift eastward to the same extent as the former,possibly because of the lower electron velocity.The 30-100-keV electrons are distributed in the L = 1.8-2.1 L-shell range,in contrast to the100-300-keV electrons which are at L= 1.67-1.9.This is consistent with the perspective that the energy of the VLF-waveinduced electron flux enhancement decreases with higher L-shell values.We expand upon the rationality of the simultaneous enhancement of the 30-100- and 100-300-keV electron fluxes through comparison with the cyclotron resonance theory for the quasi-linear wave-particle interaction.In addition,we interpret the asymmetry characteristics of NWC electric power distribution in north and south hemisphere by ray tracing model.Finally,we present considerable discussion and show that good agreement exists between the observation of satellites and theory. 相似文献
34.
It has been found that for a fixed degree of fuzziness in the coarsened references of measurements,the quantum-toclassical transition can be observed independent of the macroscopicity of the quantum state.We explore a general situation that the degree of fuzziness can change with the rotation angle between two states(different rotation angles represent different references).The fuzziness of reference comes from two kinds of fuzziness:the Hamiltonian(rotation frequency)and the timing(rotation time).For the fuzziness of the Hamiltonian alone,the degree of fuzziness for the reference will change with the rotation angle between two states,and the quantum effects can still be observed with any degree of fuzziness of Hamiltonian.For the fuzziness of timing,the degree of the coarsening reference is unchanged with the rotation angle.During the rotation of the measurement axis,the decoherence environment can also help the classical-to-quantum transition due to changing the direction of the measurement axis. 相似文献
35.
以"分子"教学为例,剖析教学中多次让学生"画水"所包含的遵循学生认知规律的特色,并结合相关教育理论,提炼出遵循学生认知规律的一些教学策略。 相似文献
36.
Tang Li Yang Haowei He Liang Wang Meng Zhu Baokun Liao Tougen 《Accreditation and quality assurance》2019,24(5):341-349
Accreditation and Quality Assurance - A little nicotine in tobacco leaf is non-ionized, which is also known as free-base nicotine (FBN). The dynamic equation existed between FBN and ionized... 相似文献
37.
38.
39.
《Radiation Physics and Chemistry》2004,69(5):379-386
Pulse radiolysis of aqueous diphenyloxide (DPO) has been performed under various experimental conditions. The OH radicals react with DPO on various positions of the molecule with a rate constant, k=2.1×1010 l mol−1 s−1. The major reaction step appears to be a cleavage of the C–O bond of DPO resulting into C6H4OH (λ=285 nm) and C6H5O(λ=325 nm) radicals in addition to DPO–OH adducts. They disappear according to a second-order reaction. In the presence of air or in a gas mixture of N2O:O2=4:1 the DPO–OH adducts are scavenged by oxygen, resulting into peroxyl radicals, which are long-lived species. For the reaction of eaq− with DPO a rate constant, k=2×1010 l mol−1 s−1 was found. 相似文献
40.
《Journal of Electrostatics》2014,72(4):315-321
Irregularity in charge distribution of an insulator may lead to accelerated aging and electrical breakdown. However, knowledge of charge distribution on the insulation surface is still insufficient albeit has gained worldwide attention. The insufficiency is particularly on the charge profile along the string insulator under AC excitation. Therefore, charges distributions on the surfaces of glass insulators without installed grading ring are investigated in this paper. Simulation and experimental results were found in good agreement when studying the charge distribution pattern along glass insulator string where the polarity of charge swinging occurs at the center of suspension string insulator of I-type. 相似文献