一种基于神经网络的谐波电流抑制方法

在传统谐波注入法基础上提出一种神经网络自适应谐波电流抑制方法，根据自适应噪声抵消技术运用人工神经网络的自适应和自学习特性检测出谐波电流并注入电力系统，达到抑制谐波的目的。通过对一典型正弦电流的仿真研究结果表明，该方法是可行和有效的，它不但有较高的精测精度，而且能跟踪检测，根据环境的变化能自适应地调整神经网络的权值，以便正确地检测出线路的谐波电流。     

基于 Hopfield 神经网络的谐波电流检测方法

在对各种谐波电流检测方法进行简单比较的基础上,提出了一种基于Hopfield神经网络(HNN)的谐波电流检测方法.该方法将HNN优化理论用于电力系统的谐波检测,自适应地准确检测出电网基波和各次谐波分量的幅值和相角.采样数据处理速度快,实时性好,网络不需要预先进行训练.仿真结果表明,该方法具有很好的实时性、较高的检测精度以及自适应跟踪负载电流变化的能力.     

谐波电流的自适应检测新方法

提出了一种基于LMS自适应算法的谐波电流检测方法,通过引入收敛因子可快速检测出谐波电流,具有较快的动态响应特性,仿真结果验证了该检测方法的有效性.     

神经元自适应谐波电流检测系统的仿真研究

根据有源电力滤波器神经元自适应谐波电流检测方法的算法公式和系统结构,提出了神经元自适应谐波电流检测系统的一种模拟电路实现方案,并用ＰＳＰＩＣＥ软件做了计算机仿真研究。仿真结果证实了所提出的模拟电路实现方法的有效性和可行性。     

一种快速自适应谐波检测的APF仿真研究

提出了一种快速自适应谐波检测算法和三角载波电流控制相结合的方法,以基波电流作为控制参考,运用于三相三线制有源电力滤波器中.仿真结果表明该方案在电网电流存在畸变的情况下,能很好地自适应跟踪谐波,并且具有很好的动态响应和较高的检测精度等优点.     

一种改进的基于正弦函数变步长LMS算法的谐波检测方法

自适应谐波电流检测方法相对于其他谐波电流检测方法来说,具有实现简单、鲁棒性强等特点。针对有源电力滤波器(APF)的滤波特性,提出了一种改进的基于正弦函数变步长LMS算法的谐波电流检测方法。对于单纯抑制系统谐波电流以及同时兼顾抑制谐波与补偿无功这两种情况,该改进算法分别采取与传统方法不同的反馈信号作为自适应滤波器权系数迭代反馈量,并采用基于正弦函数的变步长LMS算法控制步长的变化,达到有效跟踪目标信号的目的。详细推导了两种情况下系统的直接误差信号,并将其作为正弦函数LMS算法的控制量来控制步长更新。通过MATLAB仿真对改进算法与传统固定步长算法进行比较,证明了改进算法的优越性。     

一种用于船舶电网的并联型APF仿真分析

非线性电力电子装置在船舶电力系统中得到广泛应用的同时,对船舶电网也造成了一定量的谐波污染。谐波污染不仅会影响船舶电网中用电设备的可靠性而且还会对其安全运行造成隐患,势必要对电网中的谐波进行治理。有源电力滤波器(APF)能够有效对电网中的谐波进行抑制,是目前常用的谐波治理方法。结合船舶电网的实际情况建立了可用于船舶电网谐波治理的并联APF模型,并对传统有源电力滤波器的谐波电流检测方法进行改进,提出运用自适应滤波器来实现传统谐波电流检测方法中的低通滤波器,能够快速而准确地对电网谐波电流进行检测。仿真结果验证了所提算法和建立模型的正确性和有效性。     

—种基于瞬时无功功率的电力系统谐波检测改进法

有源电力滤波器的工作性能很大程度上取决于对谐波和无功电流高精度、实时的检测上。提出了一种基于瞬时无功功率理论ip,iq谐波检测法的改进法,构建了一种最小均方（LMS）自适应滤波器作为检测电路中的低通滤波器,使检测系统获得良好的检测精度和良好的响应速度,进而获得良好的谐波补偿效果。基于MATLAB的计算机仿真实验验证了该谐波电流检测算法的正确性和有效性。     

一种基于瞬时无功功率的电力系统谐波检测改进法

有源电力滤波器的工作性能很大程度上取决于对谐波和无功电流高精度、实时的检测上.提出了一种基于瞬时无功功率理论ip,iq谐波检测法的改进法,构建了一种最小均方(LMS)自适应滤波器作为检测电路中的低通滤波器,使检测系统获得良好的检测精度和良好的响应速度,进而获得良好的谐波补偿效果.基于MATLAB的计算机仿真实验验证了该谐波电流检测算法的正确性和有效性.     

基于自适应理论谐波检测的电气化铁路有源滤波器仿真研究

随着我国电气化铁路进程的不断推进,所带来的电能质量问题日益严重,主要表现为负载电流中谐波电流和无功电流含量高,不仅会损坏电气设备、影响电力机车正常运行,还会对电网造成严重危害。本文针对以上问题,研究了适用于电气化铁路谐波补偿的混合型有源电力滤波器。本文分析有源滤波器的基本原理,结合电气化铁路负荷特性确定了有源电力滤波器(APF)的拓扑结构;研究了自适应谐波检测算法,利用MATLAB建立了电力机车电流源模型,并对谐波检测算法进行仿真;分析了控制策略,采用直流侧电压控制方法;对整个混合型APF系统进行了仿真,证明其具有良好的谐波补偿性能。     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

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.