基于改进小波变换法的风电场谐波检测

为了提高风电并网电力系统谐波检测的快速性与准确性,提出一种改进小波变换的谐波检测方法。首先,把风电并网系统电压信号的频域空间分割成低频区段与高频区段,针对低频区段信号采用小波多尺度算法分解,针对高频区段信号采用小波包进行分解,得到信号中的基波和各次谐波分量;然后,通过有效地提取出特定频率段的谐波分量进行重构来检测风电并网电力系统谐波;最后,利用MATLAB进行了仿真实验。实验结果表明:该方法能快速有效检测出谐波分量,提高了谐波检测准确度和快速性。     

基于高频方波注入的永磁同步电机转矩脉动抑制策略

传统的高频方波注入法,利用转子的饱和凸极效应,可提升转速控制精度,但该方法也导致电流中含有大量的谐波而产生畸变,对电机的转矩脉动产生负面影响。在传统高频方波注入法的基础上,通过谐波电流抑制算法,利用坐标变换及低通滤波器采集出5、7次电流谐波分量,将采集的数据经过谐波电压补偿。提出了一种谐波抑制高频注入的方法。该方法消除电机工作中电流谐波分量,达到抑制转矩脉动的目的。仿真和实验结果表明了该算法可以有效地抑制定子电流的畸变,降低转矩脉动,且具有较高的灵活性。     

Excel和Matlab在简单电力系统谐波分析中的应用

介绍了一种分析和解决简单电力系统中谐波问题的简单方法.首先在Excel电子表格环境中,输入电力系统的原始数据,然后利用Excel内置函数和VBA编程可以计算出系统不同地点、不同元件的谐波阻抗值,并计算出各次谐波的系统阻抗和时域中各次谐波的电压和电流,从而计算出系统的总谐波畸变率;利用Mat-lab绘出系统阻抗扫描图,可以检测系统的谐振点.利用Excel自动计算的强大功能,可以方便的进行多方案设计计算,研究多种实际因素对总谐波畸变率的影响.     

小波包分析在电气化铁道牵引网故障测距中的应用

参考了小波分析的基础上,采用了小波包分析方法对故障实行定位。由于牵引网故障暂态行波中的高频成分多而复杂,小波分析只能对信号的低频部分进行分解,而没有对高频部分进行分解。于是提出将故障信号经过小波包分析,对高频信号进行了进一步的分解。再结合求导算法和相似性算法对故障信号进行分析。通过实测的数据分析可以得出该方法具有更好的优越性,准确的实现了故障定位。     

基于经验模式分解的音频带宽扩展算法

音频带宽扩展是现代音频编解码器的重要组成模块,它可以大幅降低编码码率。现有方法大多将低频复制到高频,然后利用少量高频参数进行调整得到重建的高频信号。这种复制方法假设高低频信号间具有相关性;但是,当这种相关性变弱时,编码质量急剧下降。为解决该问题,提出一种经验模式分解的方法重建高频信号。首先对高频和低频激励信号进行经验模式分解,然后选择与高频模式分量相关度较大的低频模式分量作为高频重建中的源信号。在得到高频重建的源信号后,再利用模式分量能量进行调整;最后通过源滤波器模型合成高频信号。实验结果表明,该方法与3GPP WB+和AVS P10编码标准中的带宽扩展算法相比,编码质量得到了明显提升;与最新的3GPP EVS中的时域带宽扩展算法相比,主观音质相当,码率下降33.3%。     

油田配电网的谐波分析与集中治理

通过对油田配电网谐波源的调查和频谱分析,提出了一种基于网路结构的谐波集中治理方法。首先建立了系统各次谐波的节点导纳矩阵,求解对应的灵敏度矩阵,并运用灵敏度矩阵寻找配电网中配置各次谐波滤波器的候选位置。然后采用改进遗传算法对滤波器进行优化配置,在保证网络各节点谐波电压含量和总谐波畸变率符合谐波标准以及滤波器安全可靠运行的前提下,使得全网滤波器的投资费用最少。实例分析结果表明,提出的无源滤波装置的最优配置方法有效,给出的谐波治理方案能够有效地抑制网络中各节点谐波电压的畸变。     

基于多参数正则化的高分辨率图像重构算法

根据完全重构滤波器的性质,提出一种基于多参数正则化方法的高分辨率图像重构算法。该算法利用多参数正则化方法,恢复图像的高频部分,然后将恢复的高频信号与低频部分叠加,得到重构的高分辨率图像。由于该算法沿不同滤波方向选取不同的正则化参数,因此有效地抑制了噪声对重构图像的影响,改善了图像在边缘部分的重构效果,从而弥补了己有方法的不足。对所提出算法的收敛性进行了分析,并通过数值实验验证文中所提出算法的有效性。     

Hilbert-Huang变换方法在电网谐波及间谐波分析中的应用

本文将Hilbert-Huang变换方法应用于对电网谐波及间谐波信号的分析中.该方法包含两部分：经验模态分解与Hilbert变换.首先,运用经验模态分析法可以提取到各次谐波分量,然后再通过Hilbert变换可以计算得到其瞬时幅值与瞬时频率.仿真结果验证了此方法对电网谐波与间谐波信号分析的有效性.     

基于滑窗迭代DFT和小波包分析的谐波电流检测方法

为了对电网中负载电流信号进行有效地检测,给出一种基于滑窗迭代DFT和小波包分析的谐波电流组合检测方法;方法先利用滑窗迭代DFT将负载电流信号中的基波分量和谐波分量分离,再用小波包对前面得到的谐波分量进行分析,更加精确地分离出残余基波和各次谐波含量;利用MATLAB进行仿真实验,实验结果验证了所给方法的有效性和准确性.     

基于心电信号频域特征的身份识别方法

本文提出了一种基于频域特征的心电信号身份识别的方法,利用傅立叶变换对心电信号进行频域分析,得到心电信号的幅频特性图谱,提取包括信号频域斜率、谐波数、幅度差值等特征参数,以及根据傅里叶变换,得到心电信号的能量谱中的低频能量、高频能量占总能量的比率构成代表心电波形的特征向量.分别利用相关分析和神经网络分类器进行识别,其中基于神经网络的身份识别准确率达到96.4%.     

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.     

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.     

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.     

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.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.