基于内插型双边带滤波器的时域自适应滤波

针对过采样条件下直接序列扩频（DSSS）系统中采样样值相关性造成在使用传统时域自适应滤波窄带干扰抑制方法时扩频信号失真的问题,提出一种改进的时域自适应滤波方法.该方法基于内插型双边带滤波器,采用抽取-内插结构,结合最小均方（LMS）算法进行自适应权值更新,实现窄带干扰抑制.理论分析和仿真结果表明,在高信噪比情况下,该方法与常规自适应滤波方法比较,具有更小的信噪比回退和有用信号畸变;同时低信噪比情况下,其误码率性能也略有优势.      

强噪声下小波包自适应算法的研究

低信噪比下信号检测一直备受关注.已有的方法多集中于FFT变换和自适应滤波算法的结合,尤其是变步长因子的改进上.随着小波、小波包的时频分析能力和变分辨特性日趋完善,小波逐渐成为信号处理的首选.本文算法先把信号小波包分解,然后自适应滤波运用于分解后的每个子波,最后小波包信号重构,并以罗兰-C信号为例验证其有效性.     

变换域自适应滤波技术在扩频通信抗窄带干扰中的应用

在众多变换域抗窄带干扰的信号处理技术中,自适应滤波具有对干扰频率不敏感的优点,且其权值调整是基于对系统参数的优化.但由于必须通过迭代收敛达到稳态解,自适应滤波算法不能锁定快变干扰.文中利用正交加速算法来提高最小均方误差(LMS)算法的收敛速度,推导出了使用变换域自正交加速算法时系统误码率的解析表达式.仿真结果表明,采用自正交化可以大幅度提高自适应算法的收敛速度,从而为基于变换域自适应滤波技术的接收机走向实用提供了理论基础.     

一种自适应Morlet小波滤波方法及其在滚动轴承早期故障特征提取中的应用

针对滚动轴承早期故障信号微弱,故障特征难以提取的问题,提出了一种基于混洗蛙跳算法(shuffled frog leaping algorithm,SFLA)的自适应Morlet小波滤波方法.首先利用自相关分析去除宽频随机噪声,然后通过SFLA优化Morlet小波的滤波参数,获得在最小信息熵下的中心频率和滤波带宽.由自适应Morlet小波滤波器获得的滤波信号,其中的冲击成分可以很好地被表征.最后对滤波后的信号做包络谱分析即可提取滚动轴承的故障频率.实验表明,自适应Morlet小波滤波方法可以成功地从低信噪比信号中提取出周期冲击特征,对于滚动轴承早期故障振动信号,能够有效地提取冲击特征频率实现滚动轴承早期故障诊断.     

变换域自适应滤波技术在扩频通信抗窄带干扰中的应用

在众多变换域抗窄带干扰的信号处理技术中,自适应滤波具有对干扰频率不敏感的优点,且其权值调整是基于对系统参数的优化。全由于必须通过迭代收敛达到稳态解,自适应滤波算法不能锁定快变干扰。文中利用正交加速算法提高最小均方误差（ＭＬＳ）算法的收敛速度,推导出了使用变换域自交加速算法时系统误码率的解析表达式。仿真结果表明,采用自正交化可以大幅度提高自适应算法的收敛速度,从而为基于变换域自适应滤波技术的接收机走     

基于小波尺度相关的船舶轴频电场检测方法

为了提高低信噪比下对海水中被衰减的轴频电场信号的检测能力,提出一种基于小波尺度相关的船舶轴频电场检测算法.首先,使用小波变换对信号进行分解,并对噪声能量进行估计;然后,利用小波尺度相关对噪声和信号进行分离,并采用均值滤波降低小波系数平移的干扰;最后,提取最大尺度的相关系数作为特征值,对信号进行滑动检测.通过该算法和小波熵算法对实测数据和仿真数据进行处理和对比分析,结果表明:此算法在低信噪比情况下具有更高的稳定性和更好的检测效果.     

基于小波包的变换域通信系统窄带干扰抑制技术

为了使变换域通信系统(TDCS)能够对窄带干扰频率进行精确定位,提高生成的基函数的频带利用率,提出了一种基于小波包变换的基函数生成方法.该方法采用树结构算法对信号进行分解,准确判断出窄带干扰的频率位置,改善了有用频带被过多剔除的情况.仿真结果表明,采用该方法的变换域通信系统比采用其他方法的变换域通信系统具有更强的干扰抑制能力和更好的自适应性.     

一种多分量线性调频信号参数估计方法

为解决目前传统方法在低信噪比时对多分量线性调频信号参数估计不理想的问题,提出一种新的参数估计算法.该算法将分数阶傅里叶变换和小波变换很好地结合起来,对经过分数阶傅里叶变换后的信号用小波进行滤波,并最终估计信号参数.仿真结果验证了该算法的有效性,可适用于低信噪比环境.     

抑制局部放电混合干扰的浮阈值量化算法

由于局部放电(PD)信号与含有的混合干扰(白噪和窄带)在能量分布频段上存在明显差异,根据小波包变换各节点分解系数能够有效反映被分析信号能量变化的特点,建立一种以反映PD信号分解系数中噪声能量为判据的浮阈值量化算法,使得最优基下各节点阈值随相应节点分解系数中信号噪声强度的变化而变化,自适应地决定各节点最佳阈值选择,以实现对PD信号分解系数更精细划分。通过对含有混合干扰的仿真与实测PD信号的小波包最优分解,分别用传统全局阈值量化算法与笔者建立的浮阈值量化算法进行了干扰抑制效果的对比,结果表明：后者具有更强的抑制混合干扰的能力,且混合干扰抑制前后PD信号波形相似度更高。     

窄带干扰下自组织网络通信中自适应非线性滤波方法研究

针对传统滤波方法抗干扰能力差、收敛性低的弊端,提出一种新的窄带干扰下自组织网络通信中自适应非线性滤波方法。介绍了MLMS方法,给出滤波器结构。采用非线性函数对估计误差信号施行相关处理,通过MLMS法对抽头系数进行更新。为了降低信号干扰样本的干扰,利用非线性函数对其进行修正,给出新的抽头系数更新方程。根据正弦干扰对白高斯噪声信号进行描述,获取最佳抽头系数。通过输出信噪比和输入信噪比的比值对所提方法抵御窄带干扰的性能进行评价。将所提方法应用于窄带干扰自组织网络通信中,结果表明,所提方法抑制干扰能力强、收敛性能高、得到的信号效果好。     

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.