基于改进S变换技术的轧钢厂电机电压检测方法

由于电压暂降补偿方法是准确获取电压暂降的主要特征,基于深入分析电压暂降问题,将改进的S变换技术用于电压特征检测,提出一种新的电压暂降特征检测方法。该方法在介绍S变换的基本原理基础上,提出改进的S变换技术,进而提出基于改进S变换技术的电压暂降特征检测方法和实现步骤。以达州钢铁集团轧钢厂感应电动机为研究对象,利用改进的S变换技术,计算电机电压暂降幅值、相位跳变和持续时间等特征向量。通过大量的仿真实验,结果表明提出的电压检测方法具有计算量小、准确度高、抑制噪声干扰效果好等优点。     

基于改进S变换的电压暂降检测方法

电压暂降是一种重要的电能质量扰动问题,其主要参数包括暂降的起止时刻及暂降幅值.本文用改进S变换对电压暂降信号进行分析,用基频幅值-时间差分曲线定位暂降的起止时刻,通过调节改进S变换高斯窗函数的两个因子使定位更加准确,并给出了调节准则和参数优化范围.通过找到基频幅值曲线的最小值点,对该点前后各半个基波周期的数据进行快速傅里叶变换求得暂降幅值.仿真表明:本文的方法使定位及幅值计算都更加准确.     

基于改进的 STU KF 电压暂降检测方法

为了准确检测电压暂降,提出一种基于改进的强跟踪无迹卡尔曼滤波(STUKF)的电压暂降检测方法.该方法在建立的电压信号状态模型基础上,利用改进的STUKF对发生暂降的电压信号状态进行跟踪,从而实时提取出电压的幅值和相位信息.仿真结果和实际数据检测表明,所提方法能够有效地检测电压暂降的幅值、持续时间和相位跳变.与传统的STUKF相比,改进的STUKF跟踪精度更高、鲁棒性更强.     

基于敏感设备电压耐受改进曲线的电压暂降评估方法

为了合理、精准地衡量电压暂降事件对用电设备产生的影响,需对电压暂降严重性进行评估.针对现有评估方法中敏感设备电压耐受曲线的分布存在突变问题,提出一种基于敏感设备电压耐受改进曲线的电压暂降严重性评估方法.首先,基于最小二乘的方法,结合设备电压耐受能力及电压暂降的规律,拟合出具有连续、单调特性的敏感设备电压耐受改进曲线.然后,根据电压暂降严重程度函数与设备电压耐受能力间的关系,建立基于敏感设备电压耐受改进曲线的电压暂降严重性函数模型.最后,基于土耳其Thrace一家纺织厂变电站发生的电压暂降事件数据进行实例验证.验证结果表明改进后的严重性函数的评估结果更合理、更符合客观实际.     

电压凹陷的改进S变换检测方法

提出了一种利用改进S变换模时频矩阵检测电压凹陷特征量的方法.为达到最优分析性能,在保证基频幅值向量平直性的基础上,使其过渡时间最小,以此确定改进S变换的窗宽系数,从而能够准确检测出持续时间小于2个周期的短时电压凹陷幅值.提出利用基频幅值差分向量检测电压凹陷的起止时刻,以克服现有S变换方法对噪声敏感和定位效果受突变幅度影响的缺陷.通过与S变换方法的比较,证明了本文方法明显提高了电压凹陷幅值检测能力和起止时刻定位能力.     

基于希尔伯特黄变换和决策树的电压暂降源识别方法

电压暂降源的准确识别对治理电压暂降问题和改善电能质量具有重要意义。雷击故障和普通故障造成的电压暂降特征不同,对电网的影响有差异,相应的治理措施也不同。传统的暂降源识别主要考虑了短路故障、变压器激磁和大型电机启动三类暂降源,将雷电冲击单独列为一类进行识别,提出一种基于希尔伯特黄变换(Hillbert-Huang transform, HHT)和决策树的暂降源识别方法。基于HHT变换后的曲线差异提取分类特征,并通过构建分类决策树自适应确定特征阈值。使用PSCAD/EMTDC搭建了普通故障、雷击故障、变压器激磁和电机启动四类暂降源仿真模型,通过仿真验证并与现有识别方法对比分析以及实际应用结果表明,所提方法简单有效、识别准确率高、有实用价值。     

基于空间矢量的单相电压暂降检测方法

电压暂降检测对电能质量分析和控制具有重要意义.提出一种基于电压空间矢量的单相电压暂降检测方法.通过对三相电压信号进行Clark变换,结合Euler公式构造三相电压空间矢量,根据空间矢量在复平面上的椭圆轨迹进行电压暂降的检测并识别出故障相.由椭圆长半径、短半径和倾斜角求出电压暂降过程中电压相位角跳变值,根据相位角跳变值对原始电压数据进行移相,最后计算出电压暂降深度.仿真实验取得了良好效果,表明该方法具有一定的应用价值.     

基于相空间重构的电压暂降分类方法

电压暂降的快速分类对改善电能质量有重要意义.针对电压暂降分类存在的复杂、实时性不强及误判等问题,提出基于相空间重构的电压暂降分类方法.对无扰动的三相信号进行相空间变换,使其转化为简单的同心圆,据此得到变换矩阵.对持续时间不足1周期的信号,通过变换矩阵重构周期信号;对持续时间为1周期以上的信号,使用变换矩阵进行处理.根据暂降到达稳定状态时的3点,得到三相相量图.对所得的相量图进行分析,得到电压暂降的分类结果.仿真实验及算例分析结果表明:该分类方法具有可行性.     

基于广义S变换的信号提取与抑噪

S变换结合了短时傅里叶变换和小波变换的优点,是非平稳信号时频分析的有力工具.为了提高S变换在应用中的实用性和灵活性,该文将S变换改造成时频分辨率可调的广义S变换.广义S变换具有多分辨率特性,利用其高质量的时频分布,在时频域中设计了两种时频滤波器.前者用来实现非平稳信号中特定信号分量的提取,也可滤除处于特定时频平面中的噪声;后者直接应用广义S变换的时频谱实现,用于含高斯白噪声信号的滤波,达到了突出有效信号和压制噪声的效果.几种信号模型的仿真试验显示了它们在信号提取和抑制噪声中应用的有效性.     

结合非下采样Contourlet变换的改进图论MST图像分割

为提高图论最小生成树的分割精度,保留更多边缘细节,提出了一种结合非下采样Contourlet变换(NSCT)及改进图论最小生成树(MST)的图像分割方法.首先,将图像进行NSCT分解,得到一个低频子带和多个高频方向子带,对各高频方向子带采用改进的贝叶斯萎缩阈值抑制噪声,通过模极大值检测关联边缘的像素点,结合低频子带灰度值和高频子带系数构造多尺度多方向的MST边权,并加重关联边缘的边权重;然后,从区域内部和区域间差异函数以及合并机制方面对MST分割算法进行改进,降低噪声或孤立点的影响;最后,改进和声搜索算法的"调音"策略,自适应获取MST分割算法的最优参数,得到全局最优分割.实验结果表明:与其他改进图论MST分割方法相比,文中方法的抗噪声性能好,提高了分割精度,且错分率低,所得图像边缘细节明显,分割效果较好.     

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。     

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.