Analysis on the method of selecting nodes on the erosion diagnosisof grounding grid

The number of underdetermined equation, which is limited by the grounding down lines, reduces the grounding grid corrosion diagnostic precision. Based on the grounding grid fault diagnosis method and sensitivity analysis, the value of slip resistance change on the impact of the port resistance in several cases, such as small span, large span and edge, center and symmetrical cross line of the grounding grid, is analyzed. A new method which is used to select the node pairs to calculate the corrosion situation of grounding grid is presented. Based on this method, the simulation analysis and field test has been done. The experimental results show that this method could improve the accuracy and efficiency of grounding grid fault diagnosis.     

A Method for State Diagnosis of Grounding Grid

This paper discuses the method with which the corrosion of the grounding grid can be diagnosed .A grounding grid can handled as a circuit network. With the application of circuit network graph theory and the fault diagnosis theory of analog circuit and optimization, the fault diagnosis equations can be set up. This equations is figured out by Matlab, and the corrosion status of the grounding grid can be deduced from the result.     

Analysis of Theory and Method about the Corrosion as well as the Broken Point of the Grounding Grid

The paper studies the theory about the corrosion as well as the broken point of the grounding grid in power plants and substations. By using sensitivity analysis, failure diagnosis equation is put up through rigorous theoretical analysis. Meanwhile the problem of morbid equation is solved by introducing lowest energy theory and technique of optimiation to diagnosis equation solution of grounding grid combined with definite constraint condition and linear or non-linear objective function, the fault diagnosis equation is discussed. The results of emulation calculation and analogous experiments verify the correctness,feasibility and practicality of the theory and method.     

Computation method of magnetic field inverse problem on grounding grids fault diagnosis

Grounding grids are the guarantee of substation running safety. The fault of grounding grids is a threat to people and equipment in substations. A method to diagnose the fault of grounding grids based on magnetic field inverse problem. The inverse problem of magnetic field is established by injecting and extracting a low frequency current. The morbid of inverse problem is solved through regularization and Newton iteration method to obtain the distribution of the mesh currents. The approximate distribution of the magnetic field is calculated to diagnose the fault of the grounding grid. A 4×4 substation grounding grids is taken as an example. By comparison of the forward problem result, the error is under 3%, so the prposed method of inverse problem is verified. The selection of measurement point is discussed, and 40% of the number of meshes is accounted to approximate the real distribution of the magnetic field on the grounding grids.     

Step-by-step Method of Structural Damage Diagnosis

Base on the existing step-by-step structural damage diagnosis method, a three-step structural damage diagnosis method is developed. According to the analysis of the characteristic of genetic algorithm, a new idea of excluding the undamaged element by means of step-by-step evaluation is developed to deal with the damage diagnosis problem. In this method, sensitivity genetic algorithm is used to exclude the undamaged element step by step and residual force method is used to fix the damage district. According to the simulation research of a 2D framed structure, it is shown that the step-by-step structural damage diagnosis method can gain the ideal results when it's difficult for a single damage diagnosis method to get the good results. It is also indicated that sensitivity genetic algorithm is a good way to exclude the undamaged element step by step.     

雷电引起接触电压、跨步电压导致生物伤害的损害概率计算方法探析

为了提高人员生命损失风险计算的针对性、准确性,为人工接地装置安全布设提出建设性的指导意见,通过对人工接地装置泄流时接触电压、跨步电压的计算方法的分析,确定了人工接地体泄流时接触电压、跨步电压导致人身伤亡的损害概率的定量计算方法。计算时,通过对接触电压、跨步电压计算值与人体耐受接触电压、跨步电压阈值的比较分析,确定能达到该阈值的最小雷电流幅值,再通过对项目所在位置雷电活动特征的分析,确定可能超过灾害阈值对应的雷电流幅值,即可能产生风险的雷电流所占的频率,认为该频率即为接触电压、跨步电压导致生物伤害的损害概率。对人工接地装置接触电压、跨步电压的计算以垂直接地极为例,同时考虑了冲击电流较工频电流对计算方法的影响。     

Grounding Resistance Calculation Methods of SZJ Grounding System

With theoretic analysis, lab experiment and engineering application, it is indicated that the SZJ grounding system is a new type grounding system which distinctly reduces the grounding impedance of grounding grids, especially of grounding grids in the zones with high-resistivity or grounding grids with scanty area. The design and calculation method for application of SZJ grounding system is also studied.     

Prediction Model of Soil Erosion Amount in Highway Engineering during Construction Period in Mountainous Area

The highway project in mountainous area will lead to serious soil erosion,due to its long road line and large volume of the work.While the program of water and soil conservation is drawn up,the prediction of the amount of soil erosion is needed. The whole amount of soil erosion comprises primary and new soil erosion amount. The primary soil erosion amount may be predicted by the method of average erosion modulus or universal soil loss equation.The new soil erosion amount is made up of erosion amount due to disturbed earth surface and discarded soil.Finally, the prediction model of soil erosion amount about a specific highway project during its construction period in mountainous area is analyzed.     

沂河流域土壤侵蚀分布特征研究

为探索沂河流域土壤侵蚀的强度和规律,利用ArcGIS的空间分析与统计分析功能,从高程、坡度、土壤类型、土地利用4个方面,对沂河流域土壤侵蚀的空间分布特征进行研究。结果表明：（1）流域土壤侵蚀总体以中度侵蚀为主,存在较为明显的区域差异;（2）侵蚀主要发生在600 m以下区域,其中高程位于200~400 m之间的区域侵蚀面积最大;（3）5°以下以及8°~15°坡度级土壤侵蚀面积较大,土壤侵蚀随坡度的增加总体都呈现出先增强后减弱的趋势;（4）土壤总面积越大,侵蚀面积也越大。石质土、粗骨土的土壤侵蚀率较高,潮土和砂姜黑土的土壤侵蚀率较低;（5）耕地、草地和林地侵蚀面积最大,林地、草地、未利用地土壤侵蚀率较大,水域土壤侵蚀率最小。     

基于USLE模型的滹沱河上游黄土区土壤侵蚀空间特征研究

滹沱河是山西省面积较大的支流之一,研究滹沱河上游的土壤侵蚀对于建立山西省生态修复体系具有重要意义。以忻州市滹沱河上游为研究区,以遥感影像数据、数字高程模型数据、降雨数据、土壤类型数据为基础,利用GIS、RS技术,结合美国通用水土流失方程(USLE)估算滹沱河上游流域的土壤侵蚀模数。结果表明：（1）2015年滹沱河上游的土壤平均侵蚀模数为2538.9 t/(km ²·a),整体属于中等侵蚀水平。土壤侵蚀类型主要为微度侵蚀、极强烈和剧烈侵蚀;（2）随着高程海拔的升高,土壤侵蚀强度加大,土壤侵蚀面积减少,高程与土壤侵蚀强度呈正相关关系,与侵蚀面积呈负相关关系。剧烈侵蚀在各个高程带均有分布,在[500,1000)高程带中,微度侵蚀的面积范围最大;（3）研究区在0—5°带的土壤侵蚀面积分布最大;（4）牧草地的土壤侵蚀分布范围最广,其次分别为耕地>林地>园地>城镇村及工矿用地>水域及水利设施用地>其他土地。研究结论可为政府制定土壤侵蚀治理的技术方法、治理方案以及治理工程类型、规模及布局等提出科学依据。     

Research on Lightning Intruded Wave for 500 kV Substations

The study on overvoltage for 500 kV substation caused by lightning intruded wave is presented. In this paper, we calculate by using electromagnetic transient program (EMTP) and combine substation with incoming lines ,so some influence factors can be considered such as impulse voltage second characteristic of insulator strings, lightning stroke point on the incoming lines and impulse grounding resistance of towers. The results show that the method is close to the practice and some factors of incoming lines are important to overvoltage.     

Calculating the Hollowing-center Grounding Device Resistance Based on the Surface Charge Simulation Method

An equivalent model for hollowing-center grounding device is proposed, the hollowing-center grounding device resistance is calculated with the surface charge simulation method and the computer programme is programmed based on this model. The accuracy of the model and method is validated by experimentation.     

Application on Extracting Feature in State Monitoring and Fault Diagnosis

With the development and application of information and internet and virtual instrument technology ,the virtual globular company based on internet arises .To study remote state monitoring, remote fault detection and diagnosis about large scale, complicated and integrative equipment become very important. In the whole fault diagnosis system , the detecting ,data acquisition is original ,processing; transform and extracting features with the signal detected is a key factor. The theories and methods used in mechanical fault diagnosis is stated. The application of signal process and its feature extracting methods is introduced which are time domain, frequency domain and time frequency domain analysis, in state monitoring and fault diagnosis with its signal analysis. The processing method of random time variant special signal is given also.     

东北黑土区坡耕地侵蚀沟研究现状及进展

侵蚀沟造成了东北黑土区坡耕地大量的土壤流失,开展有关黑土区坡耕地侵蚀沟的研究对于土壤流失防治、耕地保护以及生态恢复具有重要意义。目前,在黑土区坡耕地侵蚀沟的发生发展的影响因素、预测、防治措施等方面进行了相关的研究。本文对当前的研究进行了深入的讨论和总结,指出当前对黑土区侵蚀沟分级分类缺乏细致标准的分类依据,对黑土区侵蚀沟影响因子的研究不够全面,对侵蚀沟治理的经济、生态效益以及各种治理措施的效果差异缺乏有效的定量评价。针对现有研究不足,提出了开展黑土区侵蚀沟分类分级体系的标准化,加强土壤、植物、工程措施和耕作措施等因子对侵蚀沟影响研究以及进行侵蚀沟治理措施效果的定量评价将是今后研究重点。     

基于产业集群的农产品加工企业品牌建设途径研究

以湖北省为例,结合农产品加工产业集群的特点,将其分成资源驱动型、贸易驱动型和大企业园区型3种类型,并以湖北省为例,采用案例分析方法,对每种类型产业集群内的企业品牌建设途径进行深入研究。     

An Attentive Problem of 35 kV Power Lines in Mountain Area on Protecting Against

To counteract capacitive current and resume power system, the neutral point of 35 kV power system at the mountainous area is grounding through the arc winding widely. In fact, there is great difficult in selecting the arc winding to satisfy the requirement of system. In a 35 kV power system which neutral point is grounding through the arc winding, the capacitance current are measured in site when a single-phase is grounding. From the measure data, the imbalance of three-phase voltage whether the arc winding exist or not and the operating situation of arc winding are discussed, and bring forward an attentive problem about operation of arc winding and decrease of lightning outage rates.     

Kriging and univariate modeling of a spatially correlated data

In soil science research, it is a common practice to analyze spatially correlated data sets of limited sample size. From another piont of view, even when a large data set is available the statistical techniques of analyzing spatially correlated data, such as Kriging, may not utilize the entire data set in fitting a model due to computational limitations. Of course, a model obtained by using only a portion of the data may not adequately describe the variation.In this study cover-clay thickness data collected over an area on a regular square grid were used to determine the nature of the spatial variability. After spatial semi-variances were calculated punctual and block Kriging were applied to the data. To utilize the entire data set in applying time series statistical techniques the two-dimensional data is transformed into a univariate space series by marching through the data from the northwest corner to the southeast corner of the field. Autoregressive integrated moving average and state-space models, which are new in soil science research, were subsequently used to model the spatial variation. Although the data manifests strong variation, the simple univariate models adequately describe the spatial variations. The univariate estimates are also consistent with Kriging estimates. Residual analysis and jack-knifing demonstrated the adequacy of the models. The simplicity and adequacy of autoregressive integrated moving average and state-space models as applied to cover-clay thickness data demonstrate the potential applicability of these models to soil data. The application of the three models to cover-clay thickness data is discussed.     

Distributed Data Mining on the Grid

Distributed data mining(DDM) is widely used in industrial,scientific and commercial applications to analyze large datasets maintained over geographically distributed sites,which makes DDM a major research issue on(today's) data mining field.This paper discusses the disadvantages of existing DDM systems,puts forward a service-oriented architecture for DDM on the grid and describe the process of mining under this framework.In the proposed,serviceoriented,cross-platform framework,the mining algorithm and distributed data sets are packed into the Web Service Resources(WS-Resource) respectively,which can cooperate to perform DDM as required dynamically.Finally,a grid based on local area network was built with Globus Toolkit 4.0 and take an example of association rule mining to illustrate how to work with the proposed architecture.     

Einfluß der Erosion auf die Standortproduktivität im Silomaisanbau

Influence of erosion on productivity of maize ( Zea mays L.) cultivation
Accelerated erosion was monitored in Eastern Schleswig-Holstein (F.R.G.) during the last decades. The objective of this study was to compare agricultural productivity of upper, middle and base slope segments to the respective soil parameters, reflecting results of long-term erosion.
Five soil catenas were surveyed. Each catena was divided into three segments representing an eroded area (upper segment), an area with an equilibrium between erosion, accumulation and soil development (middle segment) and an area with accumulation (base slope segment).
In 1986 soil qualities, growth characters and yield components of maize were analysed for each slope segment. At eroded slope segments vegetation cover and yield were significantly lower than at middle and base slope segments. Middle slope segments (equilibrium between erosion, accumulation and soil development) snowed balanced soil quality parameters and high maize yields with a desired combination of yield components.     

退耕政策对延安地区土壤侵蚀影响

陕北黄土高原是中国土壤侵蚀最为严重及退耕政策实施的重要区域,经过10多年退耕还林还草政策实施,区域生态环境明显改善。科学评价政策实施对土壤侵蚀的影响,有助于政策的调整及完善。以延安地区为例,基于该区域土地利用、植被覆盖、DEM及降水等数据,评价退耕政策实施对区域内土壤侵蚀的影响。结果表明：（1）受退耕政策影响,2000—2010年延安地区及＞25°区域耕地面积大幅减少,主要转化为草地和林地,转化比例分别超过80%和15%;（2）＞25°区域耕地面积减少207.8km2,减少47.50%,但仅占延安地区退耕面积的8.8%,由于＞25°区域耕地对土壤侵蚀影响较大,完全可以全部实施退耕;（3）退耕政策实施提高了植被平均NDVI值,延安地区及＞25°区域,耕地减少区域的植被平均NDVI值在2000—2010年间分别增加53.76%和55.29%;（4）计算表明,2000—2010年间耕地面积减少并未抵消降雨侵蚀力增大对土壤侵蚀的影响,若按2000年降雨侵蚀力不变计算,退耕政策确实起到了减少土壤侵蚀的作用。由于土壤侵蚀的减少是一个长期过程,所以退耕政策实施成果的维护、植被覆盖的改善和恢复需要持续进行。