The Study on Protection and Construction Mode of Urban Ecologically Sensitive Areas

The paper had analyzed the necessity and feasibility for the protection and utilization of urban ecologically sensitive areas, proposed planning urban ecologically sensitive areas reasonably and combining ecological protection with development construction. Guiding the healthy and ordered development of urban spaces was the key part and important approach to realize ecological cities. The guiding thought for development construction of ecological cities had been discussed, which was conducting laddered development according to the location and coverage of urban ecologically sensitive areas and protection grades of these sensitive areas. Then, it had proposed four kinds of protection and construction modes, which were tourism leisure green lands, relevant expositions, industrial areas and new city groups, and which had been analyzed by combining with successful cases, so as to provide feasible win-win development strategies of ecology and economy for the planning of urban ecologically sensitive areas in the future.

Research on the overload protection reliability of moulded case circuit-breakers and its test device

This paper analyzed the reliability and put forward the reliability index of overload protection for moulded case circuit breaker. The success rate was adopted as its reliability index of overload protection. Based on the reliability index and the reli- ability level, the reliability examination plan was analyzed and a test device for the overload protection of moulded case cir- cuit-breaker was developed. In the reliability test of overload protection, two power sources were used, which reduced the time of conversion and regulation between two different test currents in the overload protection test, which made the characteristic test more accurate. The test device was designed on the base of a Windows system, which made its operation simple and friendly.

Comparison the Performances of Three Earthing Systems for Micro-Grid Protection during the Grid Connected Mode

This paper presents, tests and compares three earthing systems (TT, TN and IT) for Micro-Grid (MG) protection against various fault types during the connected mode. The main contribution of this work is including the models of all the micro sources which interfaced to the MG by power electronic inverters. Inverters in turns are provided with current limiters and this also included in the inverter models to exactly simulate the real situation in the MG during fault times. Results proved that the most suitable earthing system for MG protection during the connecting mode is the TN earthing system. That system leads to a suitable amount of fault current sufficient to activate over current protection relays. With using TN system, Touch voltages at the faulted bus and all other consumer’s buses are less than the safety limited value if current limiter is included with the transformer of the main grid which connects MG. For the two others earthing systems (TT and IT), fault current is small and nearly equal to the over load current which make over current protection relay can not differentiate between fault current and overload current. All models of micro sources, earthing systems, inverters, main grid and control schemes are built using Matlab?/Simulink? environment.

Modes for Agricultural Land Protection in China

The main problem of agricultural land protection in China is the single farmland protection mode insuring arable land area only by issuing indicators,which brings great pressure to farmland's production and service function. Through establishing the corresponding relationship between food structure and some land use types,this paper points out that there is asymmetry between farmland area and per capita food consumption structure in China in recent years. Based on the above study,the paper proposes four types for agricultural land production, namely subsistence,fairly well-off,ecological and discrete type. Finally,it concludes that establishing rational type for agricultural land protection and implementing diverse farmland protection modes is the trend of farmland protection in China in the future.

Landscape Protection Mode of Traditional Villages in Ningbo

The protection of traditional village landscape is of great significance for inheriting traditional culture and keeping nostalgia.Taking the traditional villages in Ningbo as the research object,the mode of landscape protection of traditional villages based on the perspective of regional landscape was discussed.This study not only paid attention to the protection of material landscape,but also emphasized the protection of cultural belief and custom landscape,and transformed the intangible cultural belief and custom heritage into material landscape and it not only paid attention to the landscape protection with clear space mechanism of the clan courtyard,but also innovated the landscape space protection with relatively fuzzy space mechanism of the clan courtyard,and adopted different protection methods according to the clarity degree of the courtyard mechanism.In view of the village market space landscape,not only the single dependent architectural landscape protection was considered,but also the linear space landscape protection was emphasized.The idea and method of protection put forward show the historical existence of the value of ancient villages and better reflect the contemporary significance of "remembering nostalgia".

K-Modes聚类数据收集和发布过程中的混洗差分隐私保护方法

针对目前聚类数据收集与发布安全性不足的问题,为保护聚类数据中的用户隐私并提高数据质量,基于混洗差分隐私模型,提出一种去可信第三方的K-Modes聚类数据收集和发布的隐私保护方法。首先,使用K-Modes聚类数据收集算法对用户数据进行采样并加噪,再通过填补取值域随机排列发布算法打乱采样数据的初始顺序,使恶意攻击者不能根据用户与数据之间的关系识别出目标用户。然后,尽可能减小噪声的干扰,利用循环迭代的方式计算出新的质心完成聚类。最后,从理论层面上分析了以上3种方法的隐私性、可行性和复杂度,并利用3个真实数据集和近年来具有权威性的同类算法KM、DPLM、LDPKM等进行准确率、熵值的对比,验证所提方法的有效性。实验结果表明,所提方法的隐私保护和发布数据质量均优于当前同类算法。

基于k-modes聚类算法的混洗差分隐私方法

首次提出一种基于k-modes聚类算法的混洗差分隐私保护方案(简称SDPk-modes).SDPk-modes根据每个数据之间的距离划分为不同的组,得到足够的细粒度优化效用,采用基于梯度随机扰动技术使计算最优概率耗时更短;在k-modes聚类过程中,通过将数据中频繁出现的特征向量作为聚类中心点,基于属性熵的距离度量方法,加快算法收敛至聚类中心的速度,解决原始算法聚类速度慢、易陷入局部最优等问题,显著提高聚类的效果.实验验证表明,本文提出的方案优于当前同类方案.

中性点不接地柔直配电网的单极接地故障暂态过程分析及保护新方案

针对中性点不接地的柔直配电网分析了直流馈线发生单极接地故障的暂态过程,提出了单极接地保护新方案,能有效解决现有直流线路保护不能反应中性点不接地柔直配电网的单极接地故障问题。在单极接地故障的分析中,将故障发展过程分为子模块电容放电阶段和交流重新馈入充电阶段。基于叠加原理分析了子模块电容放电阶段的电流流通路径、直流馈线暂态零模电流的电流成分和变化规律,得到故障馈线暂态零模电流主要呈现衰减非周期分量特征、非故障馈线暂态零模电流主要呈现振荡衰减分量特征的结论;利用牛顿迭代法推导了交流重新馈入充电的时刻,分析了影响因素并计算了过渡过程持续的最短时间。基于子模块电容放电开始时刻至交流重新馈入充电时刻这一段的暂态特征提出单极接地保护方案。该方案利用直流母线出现的零模电压启动保护,利用零模电压极性实现故障选极,利用故障馈线暂态零模电流绝对值的第一个积分时段值大于非故障馈线的值、且呈现衰减非周期分量特征选出故障馈线。搭建仿真模型,对故障分析结果和保护方案的有效性进行了验证。

基于本地差分隐私的K-modes聚类数据隐私保护方法

分类型数据聚类是数据挖掘的重要研究内容,聚类数据中通常包含用户一些敏感信息.为保护聚类数据中的用户隐私,当前主要采用基于可信第三方隐私保护模型,但现实中第三方也存在隐私泄露风险.针对此问题,该文引入本地差分隐私技术,提出一种去可信第三方的K-modes聚类数据隐私保护方法.该方法首先利用随机采样技术对数据进行采样,然后使用本地差分隐私技术对采样数据进行扰动,最后通过聚类服务端与用户的交互迭代完成聚类.在聚类过程中,无需可信第三方对数据进行隐私预处理,避免了第三方泄露用户隐私的风险.理论分析证明了该方法的隐私性和可行性,实验结果表明该方法在满足本地差分隐私机制的前提下保证了聚类结果的质量.

基于EEMD和GP的混合直流系统双端保护方案研究

为了提高混合直流输电系统保护可靠性,提出一种基于EEMD和GP算法的双端保护方案。首先,分析控制策略、拓扑结构、分布电容因素影响下混合直流输电系统故障特征,挖掘暂态电流频域相似性特征;其次,引入并融合EEMD算法和GP算法,利用组合算法表达混合直流系统暂态电流的频域相似性特征,以两侧暂态电流关联维数的差异性建立保护判据;最后,搭建模型并验证基于关联维数的双端保护方案的正确性、可靠性和优越性。结果表明,所提方案可在较强干扰下可靠识别故障区域。

浙江省小型水库专业化管护模式探索实践与思考

浙江省针对3085座无管理单位的小型水库,积极探索深化小型水库管理体制改革,涌现了县级统管、政府购买服务、区域集中管护和“以大带小”等四种主要管护模式。本文基于这四种管护模式的应用实践和成效,对比分析各种管护模式的特点和适用条件,结合管护现状,围绕小型水库专业化管护存在的问题和面临的形势,提出了强化监管、优化市场、量化标准、推进统管、能力保障、矩阵管理等意见建议,可为持续提升小型水库专业化管护能力提供参考借鉴。

The Research on Protection of Historical and Cultural Towns and Villages in China

After the discussion of the protection process and significance for historical and cultural towns and villages and the introduction of survey and theoretical researches on them,five modes had been divided for the protection of historical and cultural towns and villages in China,which were original appearance protection,renovated utilization protection,removal protection,antique imitation development and real estate development.It had pointed out problems existing in historical and cultural villages' protection,which were that policies and regulations were incomplete and protective measures were laggard;leaders decided blindly and neglected experts' opinions;immediate interest had been highlighted and sustainable development been overlooked,capitals were lacked and management was disordered,and the publicity was insufficient and the masses had no high protection consciousness.On this basis,it had discussed the protection of historical and cultural towns and villages in the future,emphasized the completion of regulatory system and management mechanism,enhance capital investment and publicity education,and deeply explore material cultural heritages and non-material cultural heritages in historical and cultural villages,finally further studying the theories and cases.

不同土壤类型肥力变化及典型黄壤地力培育模式效果研究

通过对研究区典型分布的不同土壤类型设置监测地块,调查常规施肥和无肥措施下土壤肥力动态变化情况及对作物生物量的影响;在典型黄壤分布区选择代表性监测地块,开展有机培肥、绿肥还田和秸秆还田等地力培育技术模式田间试验,研究不同地力培育技术模式下影响黄壤土壤肥力的主要因子和土壤培肥的关键因素。结果表明,5种不同土壤类型耕地以石灰土耕地的施肥量最高,整体上各地类有机肥投入量较低,化肥投入量较高;耕作层厚度整体呈旱地大于水田趋势;土壤有机质、全氮、有效磷、速效钾和缓效钾含量均处于高至中等水平;黄棕壤在耕作熟化过程中可能因人为因素出现与自然成土过程中形成的土壤性质不一致情况;常规施肥条件下紫色土耕地增产效果显著。通过实施典型黄壤地力培育技术模式,兼用绿肥区鲜食玉米籽粒产量和秸秆产量最高;土壤养分处在较高或高等水平;地力培育技术模式显著提高了土壤微生物生物量碳和土壤微生物生物量氮含量,且施用有机肥对提高土壤微生物生物量碳和土壤微生物生物量氮含量效果最明显。

基于等效故障区段的柔性直流输电线路单端量保护方案

行波保护动作速度快,具有不依赖线路边界元件以及不受新能源控制策略影响等优点,是目前解决柔性直流输电线路中单端暂态量保护方案在弱边界情况下难以适用的有效途径之一。然而现有基于行波特征的单端量保护方案多为欠范围式保护,存在难以保护线路全长的问题。对此,该文首先通过分析线路不同位置故障时反向电流行波的传播路径,推导出在首个反极性波到达前,保护检测到同极性波的数量与故障位置的关系;在此基础上,考虑近端或末端故障时的“漏波”现象以及线路长度的影响,定义并引入“等效故障区段”的概念,以增大零线模时差在区内外故障时的差异,进而提出了基于等效故障区段的柔性直流输电线路单端量保护方案。该方案解决了现有单端量保护方案难以保护线路全长的问题,并考虑了近端或末端故障时采样率受限的影响,具有一定的容错性。最后,基于PSCAD/EMTDC的仿真实验,验证了所提保护方案的可行性。

衡水湖湿地保护区农业发展研究

衡水湖是华北平原唯一保持完整湿地生态系统的国家级自然保护区,其生态平衡对区域气候调节和生物多样性维持具有重要作用。然而,当前衡水湖湿地保护区的农业发展面临面源污染积久难消、转型升级缺乏动力、农业法规建设存在欠缺等问题。因此,衡水湖湿地保护区的农业改革应从改变传统农业生产模式、引入PPP模式加快农业转型、完善农业法规建设三方面入手,大力发展绿色低碳农业,实现衡水湖湿地保护区的可持续发展。

基于K-modes聚类算法的安徽历史文化名村分类及保护发展策略

以安徽省44个省级以上历史文化名村为研究对象,分析其空间分布特征与保护管理现状,并探讨影响其类型划分的具体因素。同时,借鉴学者关于历史文化名村和传统村落分类的研究,以地理条件、产业经济、社会生活、历史文化为主要维度,构建形成安徽历史文化名村类型划分的指标体系。基于此,运用K-modes聚类算法,将安徽历史文化名村划分为生态宜居型、文旅资源型、特色民俗型、综合发展型四种类型,并总结各类历史文化名村的典型特征,进而提出相应的保护与发展策略。

The geological heritages in Xinjiang, China： Its features and protection

The geological heritage protection and its development at home and abroad reflect the progress in the aspect from the single protection to the coordination between protection and exploitation. The geopark established by UNESCO has closely combined the protection of geological heritages with the promotion of sustainable development of local economy, which has become the best way to protect geological heritages. The geological heritages in Xinjiang, China, are characterized by their large quantity, rich variety and high grade. The complicated geologic-geomorphic environment in Xinjiang contributes to the creation of various geological heritage types and their spatial distribution, and at the same time makes them under control. The main types of the geological heritages in Xinjiang are the geologic-geomorphic landscapes and the water landscapes. The spatial distribution can be divided into five geological heritage districts： Altay, Junggar, Tianshan, Tarim and Kunlun-Altun, among which Tianshan and Kunlun-Altun are most important. Based on the first systematic investigation of the geological heritages in Xinjiang, it is confirmed that the insufficient coordination between protection and exploitation is the primary cause for the backward situation in the geological heritage protection. To solve the problem, this paper proposes 6 major protection steps--from determining the protection types, the protection forms, the protection modes, the protection grades, the protection sequences to determining the＇ protection zones, brings forward the idea of optimal-selection which integrates geoparks with geological heritage protection areas and other protection areas as protection and exploitation reserve list for 209 well as 5 corresponding modes, and makes a important geological heritages in Xinjiang.

Design and testing of a centralized protection scheme for micro-grids

Micro-grids comprise low voltage distribution systems with distributed energy resources(DERs) and controllable loads which can operate connected to the medium voltage grid or islanded in a controlled coordinated way. This concept aims to move from "connect and forget" philosophy towards a full integration of DERs. Micro-grids can provide numerous economic and environmental benefits for end-customers, utilities and society. However, their implementation poses great technical challenges, such as a new philosophy in design of protection systems. In this work, a micro-grid protection scheme is presented based on positive-sequence component using phasor measurement units(PMUs) and a central protection unit(CPU). The salient feature of the proposed scheme in comparison with the previous works is that it has the ability to protect both radial and looped micro-grids against different types of faults with the capability of single-phase tripping. Furthermore, since the CPU is capable of updating its pickup values(upstream and downstream equivalent positive-sequence impedances of each line) after the first change in the micro-grid configuration(such as transferring from grid-connected to islanded mode and or disconnection of a line, bus, or DER either in grid-connected mode or in islanded mode), it can protect micro-grid against subsequent faults. Finally, in order to verify the effectiveness of the suggested scheme and the CPU, several simulations have been undertaken by using DIg SILENT Power Factory and MATLAB software packages.

Ferrofluid Actuated Thermal Overload Relay

Thermal overload relays are economic electromechanical protection devices which offers reliable protection for electric motors in the event of overload or phase failure. Presently there are two types of overload relays which depend on the temperature characteristics of metals to provide protection by tripping the circuit. These relays lack accuracy as they do not activate the trip circuit at any exact specified temperature. In this paper we introduce a new form of thermal over-load relay actuated by ferrofluid. The ferrofluid has a very accurate transition temperature known as curie temperature. It acts as a ferromagnetic material below the curie temperature and loses the property of ferromagnetism above this temperature. By using this property of the fluid we propose an alternative method for more accurate op-eration under overload condition. This relay finds application in the protection system of electrical machines. Thus, in this paper we present a novel and simple technique for protection against thermal overloading using ferrofluid.

EFFECT OF NON-PROPORTIONAL OVERLOADING ON FATIGUE CRACK GROWTH

The effect of proportional and non-proportional overloading on mode l fatigue crack growth have been studied,and the influences of crack tip plastic zone,crack tip blunting as well as crack closure were discussed.Proportional(model I)overloading may cause more serious crack growth retardation than non-proportional(mixed mode)overloading.Therefore,for estimating the fatigue life of engineering structures to simplify a real overload which may of- ten be non-proportional as a proportional one is not always safe.