物联网在配电设备巡查及状态监测中的应用

阐述了物联网及智能电网的定义,以及物联网在配电设备的巡检及状态监控中的应用,以配电设备的巡检、状态监测为研究背景,采用射频技术采集配电设备信息,手持终端对巡检人员跟踪,手动录入配电设备信息,通过物联网的信息应用层对设备状态评估,提出了感知层、数据应用层、信息应用层的体系架构。     

基于FPGA的配电变压器在线监测及故障诊断系统设计与实现

基于FPGA灵活实现电路的运行方式功能构建出10 kV配电变压器在线监测及故障诊断系统设计,本文主要实现对电力变压器绕组温度、电压、电流、功率因数、频率及外部环境参数的数据采集实现对10 kV配电变压器在线监测,并根据其采集的参数,利用FPGA对数据的分析确定配电变压器是否处于正常运行状态.而且该系统可以通过RS232串口或RS485通信接口实现与上位机的通讯,从而使配电变压器得到很好的集中管理.最终,管理控制中心如果得到变压器的运行异常情况,能够实现其快速处理,从而有效的保障了10 kV配电变压器安全可靠运行.该系统具有精度高、稳定性好、经济实用以及可视化程度高等特点,可以满足很多实际项目的需要.     

电力变压器状态评估的加权灰靶心度分析法

针对电力变压器状态评估采用极大值极性不能正确评估正常运行状态的问题,提出一种采用加权灰靶心度算法根据电力变压器油中溶解气体含量数据以正常运行状态为标准模式的电力变压器状态评估方法。在对电力变压器状态按程度分级统计资料的基础上,提出了5级分级策略;根据电力变压器故障标准谱采用灰贡献度分析法研究确定了电力变压器油中溶解气体的权重;依据电力变压器油中溶解气体之间此消彼长的关系,提出了以正常状态为标准模式的电力变压器状态评估的加权灰靶心度分析方法,克服了采用极大值极性不能评估正常状态的问题。实验表明,该方法更符合电力变压器状态评估的实际情况,是一种科学有效的评估方法。     

油浸式大型电力变压器表面温度预测模型

为了早期发现油浸式电力变压器长期连续运行时可能存在的温升异常问题,该文提出了一种新的油浸式电力变压器表面温度预测模型,可以预测出变压器表面的正常温度。通过比较预测值与实测值的误差来预知变压器表面温度是否存在异常,进而判断变压器运行状态是否正常。预测模型参数是基于现场数据采用偏最小二乘法估计出来的,克服了传统最小二乘法参数估计结果不稳定的问题。并且从传热学原理、预测误差的均值、方差及其正态分布性等方面,合理地选择用于参数估计的数据长度。用该模型计算分析了一年的现场数据,预测结果表明该模型是正确、有效的。     

配电边缘物联网网络预警及自愈方案

配电物联网是电力物联网建设中的最后一个环节，由于具有供电路径短、负荷密度大等特点，保护和控制的难度很大，需要建立完善的配电网预警和自愈策略，形成运行方式灵活、故障预警及时、故障自愈完善的智能配电网。为此，文中提出了适用于配电物联网边缘网络固件的安全防御技术框架，对存在边缘设备中的各固件可靠性矩阵进行保护，边缘设备通过边缘服务器相互连接，形成了具备安全预警及自愈能力的配电边缘物联网技术方案。最后，通过不同环境下的模拟实验验证了文中方案的可行性。     

基于多维信息的变压器绝缘在线监测数据分析方法

针对变压器绝缘老化问题进行过程性分析,提出基于数据适应性的绝缘变化过程建模.以多维度绝缘变化信息为主要变量,考虑数据驱动下,不同维度的数据之间的适应性变化,建立统一评价体系下的在线测量模型.采用核主成分分析和支持向量机做数据整体特征挖掘,典型相关分析算法做局部特征分析,融合变压器绝缘状态信息,分别辨识聚合模型的全局及局部特征.基于实测数据条件对模型进行校验,从而实现变压器绝缘状态评估的在线分析.     

采用改进回归型支持向量机的滚动轴承剩余寿命预测方法

为准确评估滚动轴承运行状态、预测其性能退化趋势以及剩余寿命,提出一种改进回归型支持向量机(SVR)的滚动轴承寿命预测方法。提取轴承信号的时域和时频域特征,通过主成分分析(PCA)方法将特征指标融合成一个归一化综合指标来表征轴承运行状态;利用特征指标和综合指标构建训练和预测向量数据集,结合差分进化灰狼群算法(DEGWO)确定最优惩罚参数和径向基函数(RBF)核参数并构建回归型支持向量机模型;将预测数据集输入到DEGWO算法优化的SVR模型中得到轴承状态评估指标的预测值,实现轴承剩余寿命的预测。利用IEEE PHM 2012数据集验证所提方法的有效性,并将其结果与灰狼群算法(GWO)优化的SVR、网格搜索算法(GSA)优化的SVR和长短期记忆神经网络(LSTM)模型所得结果进行对比分析。仿真结果表明：与其他方法相比,采用所提方法得到的轴承剩余寿命预测均方误差分别降低了44.74%、66.67%、77.27%,决定系数则分别提高了7.25%、20.72%、11.94%,该结果说明了所提方法在轴承剩余寿命预测应用方面的优越性。     

油浸式电力变压器运行状态评估

电力变压器是电网最重要的设备之一,其可靠运行对电网维持安全稳定意义重大。如何有效、准确地评估电力变压器当前运行状态,追踪其状态劣化过程,是有效实现基于设备状态维修管理的重要条件。基于此,总结了与变压器运行状态密切相关的各项状态量指标参数,提出了追踪变压器运行状态的分析评估方法。     

采用趋势状态分析的风机齿轮箱状态在线评估云模型

为预防风机齿轮箱严重故障的发生,提出了一种结合正态云模型和趋势状态分析法的齿轮箱状态评估模型.首先,基于数据采集与监控(SCADA)系统的历史数据,采用支持向量机方法建立齿轮箱运行温度预测模型,对齿轮箱不同状态下的趋势预测特征进行分析,求取正常和异常状态时预测值的相对误差序列.然后,采用改进无确定度逆向正态云发生器,利用所求取的相对误差序列提取正常云和异常云的数字特征,构建齿轮箱状态评估云模型.该模型能够根据风机SCADA系统的实测数据,求取齿轮箱当前状态对正常云和异常云的贴近度,并采用最大贴近度原则确定齿轮箱状态.最后,利用辽宁某风机齿轮箱的实测数据对所提模型进行验证.结果表明:该模型能够对齿轮箱的早期缺陷及时预警,达到实时监测的目的.     

考虑网联汽车信息安全的交通流短时预测方法

针对智能网联汽车因网络攻击或干扰造成的信息安全及数据缺失问题,提出一种基于数据补全的交通流状态短时预测方法。首先,基于边缘计算任务卸载模型,对智能网联汽车V2X通信过程的异常数据动态辨识;其次,提出一种具有数据补全机制的图嵌入长短期神经网络模型,实现网联汽车缺失数据补全;再次,通过补全后的完整数据集构建神经网络模型,完成短时交通流状态预测;最后,选取北京市典型路段进行实验验证。结果表明,该模型应用后交通流状态短时预测效果显著提高,与其他方法相比预测误差最大降低87.4%,预测效果与实际交通流状态相比准确率达到95％,为智能网联环境下车辆信息安全与交通资源动态优化提供理论支持和技术方案。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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