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Impulse characteristic and discharge process of grounding device of pole and tower for transmission line under the action of impulse current are subject to many factors, it is unreasonable to only use a constant as grounding impulse coefficient for power frequency and impulse ground impedance conversion. The paper makes a study of and analyzes the influence pattern of grounding body material, conductor...
Permafrost is sensitive to climate change and anthropogenic activities. The interferometric synthetic aperture radar (InSAR) is a new technology allowing us to explore the interaction between the permafrost change and human infrastructures. In this paper, the deformation of the Qinghai-Tibet Railway (QTR) in Beiluhe of the Tibet Plateau (TP) between Jun. and Dec. 2014 is detected using the new mode...
Knowledging the ionization phenomenon of soil neighboring the grounding electrode is the fundament to correctly simulate the transient property of grounding devices. Soil is a solid medium, so the ionization phenomenon in soil is difficultly observed. The impulse breakdown electric field of soil is summarized, and the soil ionization phenomena under different medium were studied by X-ray film in this...
This paper investigated the factors influencing the quality of slope vegetation on highway and then constructed a comprehensive quality evaluation model. In the model, the ecology, landscape and stability functions of highway as main factors were analyzed respectively and the weights of main factors and sub-factors were determined by Analytic Hierarchy Process (AHP). Five levels were set up for evaluation...
The lightning impulse performance of grounding devices plays an important role in the lightning protection. For obtaining the impulse performance, a field test method of grounding devices impacted by large impulse current is introduced. The results by field test show that soil ionization and inductive effect are two important features of the grounding device impacted by the large surge current. By...
Slanting Grounding Rod is a new three-dimensional structure of long grounding rod. In the paper it has been in-depth analysis from both effect of resistance reduction and design programs. Different from conventional Vertical Grounding Rod, there is an angle between grounding rod and ground's vertical direction. Therefore effectively solve the problem that both effect and cost of resistance reduction...
A variety of seismic design methods for subway structures, which are present popular in China, are introduced, including the response displacement method (RDM), modified cross section racking deformation method (MCSRDM), the response acceleration method (RAM) and the pushover analysis method (PAM). A comparison calculation was then made for the same typical subway structural cross-section under the...
GIMMS/NDVI was selected as the data source in this paper. The spatio-temporal variation of the vegetation cover of the study area was monitored by employ NDVI average, retrieval of vegetation cover and linear regression trend analysis methods. The results show that: NDVI vegetation of the study area has an entirely rising trend with the rate of 0.007/10a. Especially the growth of Sandy Area, Northeast...
The contents of Cu, Pb and Zn along both sides of Xi'an-Baoji Expressway and Xi'an-Huxian Expressway in Shaanxi Province have been studied. The findings show that there is a tendency of early increase and later decrease in the contents of heavy metals with the increase in transverse distance from the axis of an expressway, the high content exits at a distance of 25–50m from the axis, and it decreases...
Field observations of water and soil loss were carried out at micro-plot scale, USLE (Universal Soil Loss Equation) plot scale and the sub-catchment scale 2000 in the sub-catchment of pine forest. Analysis of these field observation data shows that litter in forest has important hydrological function. In the pine forest, the micro-plot without litter and grass produced 123 times soil loss of that...
In the Dabie Mountains of the lower Yangtze basin, China, soil loss reduction has been deemed as important as flood control after the 1998 flood, which caused great damage to the area and its residents. After 2000 year, a project of Reforestation in cultivated land at slope was started. In this study, field observations of water and sediment discharges were carried out on USLE (Universal Soil Loss...
The old course of the Yellow River area in the North of Jiangsu Province was an extremely poor region in the history because of the extremely bad environment, such as salinization of soil, very frequent gales which caused windy sand storm and dry-hot wind which damaged the spring crop yield. In order to improve the residents' environment, forest shelter belt was constructed and forest coverage increased...
In this paper, a numerical model is presented to analyze the grounding grids. The effect of the mutual inductances among grounding system conductors on the performance of the grounding grid is investigated. It can be seen that although the effect of the mutual inductances is very small at power frequency, when a large grounding grid buried in soil with low resistivity is analyzed, the effect of the...
A new time-domain transmission-line method based on Chebyshev expansions is applied to analyze transient characteristics of grounding electrode in this paper. It takes account of both the time-variable parameters caused by soil ionization and frequency-variable parameters caused by eddy current. The analyzed results are validated by experiment. The transient characteristics of grounding electrode...
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