基于信噪比评价的阈值优选小波去噪法

在汽车自动变速器台架试验中,需要对角加速度信号进行消噪滤波。小波阈值去噪是计算量较小、滤波效果较好的消噪手段,但采用不同的小波基匹配不同的阈值规则可能会对去噪效果产生影响。为探寻相对最优组合,该文构建了近似观测信号的仿真信号,然后对该信号做了去噪实验,计算信噪比(SNR)和均方根误差(RMSE),并以此作为评价指标,从而得到相对最优的匹配组合,最后将该组合用于角加速度信号消噪处理过程,取得了较好的滤波效果。小波阈值去噪在处理含噪信号时具有效率较高、稳定性好、不易失真的特点;使用SNR结合RMSE可以对任何消噪结果作客观评判;不同的含噪信号,可能需要用到不同的小波基函数,同时匹配不同的阈值选取规则。     

基于最优匹配小波的回波与图像消噪

研究了用于消噪的小波与信号、图像的匹配原则，在采用时域波形逼近与频谱匹配原则的基础上，提出了最优匹配小波的设计方法。首先构造了两种小波滤波器组，其次给出了最佳匹配小波的设计优化算法，最后分别探讨了应用最优匹配小波对超声回波和图像消噪的方法。仿真结果表明，该方法性能优于常规的小波消噪，能较明显提高信号与图像的信噪比。     

VMD-Wavelet 联合去噪算法研究与应用

为解决天然气管道运行过程中采集到的泄漏声波信号含有大量噪声的问题, 通过研究小波、 经验模态分解、 变模态分解等常见去噪算法, 分析了泄漏声波信号的特点, 将改进小波阈值去噪和变模态分解去噪相结合, 提出了变模态分解-小波变换(VMD-Wavelet: Variable Mode Decomposition-Wavelet) 联合去噪算法。 利用该算法对典型信号进行去噪运算仿真, 结果表明, 该联合去噪算法性能优于常见算法。 最后, 将 VMD-Wavelet 联合去噪算法应用于实际采集的油气管道泄漏声波信号去噪处理, 研究发现, 该去噪算法对强背景噪声下的泄漏声波信号能取得很高的信噪比改善和很小的均方误差。     

基于相空间重构的匹配追踪混沌信号去噪

基于混沌信号和噪声在相空间轨道的动力和几何特性,提出一种相空间重构的匹配追踪混沌去噪方法。该方法利用相空间重构产生与混沌信号微分同胚的相空间集,采用匹配追踪方法将信号分解为匹配信号结构的时频原子的线性和,达到无损去噪的目的。对Lorenz混沌系统模拟试验表明,该方法具有良好的去噪效果和计算收敛性。应用该方法于混沌相关光时域定位仪实际探测信号的测试,降低互相关旁瓣平均水平9.539 4。     

基于最优FRWT的非平稳信号去噪新方法

研究非平稳信号的去噪,提出一种基于最优分数阶小波变换(FRWT)的信号去噪方法.该方法根据输出信号信噪比采用遗传算法寻找FRWT的最优分数阶值,实现非平稳信号的去噪.以带噪语音信号为例的去噪实验结果表明,采用新方法的去噪效果明显提高.     

小波包变换在煤与瓦斯突出预测中的应用

针对目前滤噪技术不能很好地使声发射监测得以准确预报的情况,进行了基于小波包变换的去噪研究.该研究利用信号的小波包分析、计算和最优小波包基选取的方法,通过计算机数值计算,模拟了强噪声下声发射信号检测,并通过Sym8小波包与小波变换去噪的比较,证明前者优于后者.用小波包变换进行消噪处理,噪声消除彻底,提高了预警准确性.     

气体钻井钻柱内声波信号传输规律分析

针对气体钻井随钻测量问题,参照医用听诊器的工作原理,提出在气体钻井中利用钻柱内声波进行井下信息传输的方法;通过建立钻柱内声波传播的数学模型并求解,得出钻柱内声波信号传输的衰减规律;利用声波导理论对钻柱的声波导特性进行分析,计算钻柱内声波的截止频率。通过管道声波传输实验,将采集声波信号与计算结果进行比对,验证了理论分析的准确性。结果表明,气体钻井钻柱内声波信号传输过程中的衰减程度随频率的升高而逐渐加剧;钻柱的内径尺寸决定了内部各阶声波的截止频率,内径越大,声波的截止频率越低;声波信号传输载波频率的选择时,应兼顾钻柱内声波信号的衰减规律和不同尺寸钻具的声波导特性,尽量选择钻柱截止频率内较低的频段,减少因高次波激发造成的衰减,延长声波信号的传输距离。     

信号等长情况下频率估计的降频域迭代分析法

从特征识别角度分析了现有频率估计方法的信号分解结构的特点,提出了一种降频域分解结构,将对应不同时间的多个单频信号融合构成一个组合信号,以利用时域已知信息并形成信息积累作用,能有效抑制干扰频率和削弱冲击噪声且计算量增加较少。为配合降频域分解结构的使用,采用了适用于信号等长情况的降频等长迭代处理算法。仿真表明该方法抗噪性和实时性好,频率估计精度比现有方法有较大提高。     

利用信号相位匹配原理的正弦信号参数估计

提出了一种利用信号相位匹配原理的正弦信号频率、振幅和相位的参数估计方法.推导了利用单元接收信号的参数估计的相位匹配计算公式及未知频率时的信号参数估计的搜索算法.该算法简单,快速.仿真计算结果证明了文中的原理及方法的正确性.     

一种基于最优小波包基的电泳荧光信号去噪方法

针对现有电泳荧光信号去噪处理方法的不足,提出一种基于最优小波包基的信号去噪方法.该方法采用Shannon熵准则选择最优小波包基,选取Penalized阈值,用量化后的系数重构得到去噪后的信号.仿真实验表明:基于最优小波包基的电泳荧光信号去噪方法在使信噪比得到提高的同时,电泳荧光信号的峰值误差也进一步减小.     

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.     

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.     

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.     

A computer generator for randomly layered structures

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

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-