抽样序列傅立叶变换的研究

分析了连续信号抽样变成抽样序列频谱分析与实际电路模型不一致 ,而理论上的频谱分析导出了对实际电路模型频谱分析适用的原因 给出了实际电路抽样连续信号完成抽样序列的频谱分析方法 ,最后根据这一方法完成了有限长离散傅里叶正、逆变换     

抽样定理对正弦特征信号适应性的讨论

对于正弦特征信号,在工程技术领域有着广泛的应用.随着数字信号处理的普遍应用,信号的抽样是首先要面对的问题.根据抽样定理,取样信号应当能够重建原限带信号,但正弦信号在不同情况下,不一定能够重建.因为正弦信号的频谱是8函数,只有两条谱线,也不是窄带信号,这样就造成了抽样的特殊性.对在抽样过程中出现的问题以及抽样的条件,进行了较为详尽的阐述.     

减少频谱泄漏的自适应同步抽样算法

叙述了DFT在连续信号谱分析中的频谱泄漏现象，分析了造成频谱泄漏的原因，讨论了一种自适应同步抽样算法。该算法利用频率跟踪技术实现采样频率的自适应调整。实验结果表明，该算法能够有效地减少频谱泄漏，在以交流电信号测量为基础的系统中具有较好的应用价值。     

带限信号抽样问题的一种改进重构算法

给出了一个具有o(t-m)(t→∞)的重构函数g(t),并由此得到了带限信号抽样问题的一个改进重构算法.     

投影栅相位法检测技术中抽样定理的适用性

分析了对于正弦信号抽样定理的适用性,给出了频谱分析时频域不发生泄漏的信号抽样条件。针对投影栅相位法三维检测技术中的抽样问题,提出了不移频处理方法和全场参考面的概念,避免了频域移频所带来的系统误差,克服了对正弦信号抽样的限制条件,并实例验证了新方法的优越性。该文的结论丰富了经典抽样定理的内容,提高了投影栅相位法三维检测技术的解相精度和稳定性,使之更符合实际应用条件。     

多维非带限信号的抽样定理

著名的Ｗｈｉｔｔａｋｅｒ－Ｋｏｔｅｌ’ｎｉｋｏｖ－Ｓｈａｎｎｏｎ抽样定理在信号分析与图像处理中起着十分重要的作用，多维抽样理论更是如此，讨论了多维抽样的重构，建立了多维非带限信号的抽样级数对其信号近似表示的混叠误差估计，并提出若干有待进一步讨论的问题。     

关于最低抽样频率的探讨

本文通过对不同类型信号的抽样过程进行理论分析,得出了各自的最低抽样频率,证明了香农抽样定理只适合低通型非周期信号的抽样。     

正弦信号抽样中若干基本问题的讨论

讨论了抽样定理对正弦信号的适用性及对正弦信号截短时所应遵循的基本原则。对形如ｘ（ｔ）＝Ａｓｉｎ（２πｆ０ｔ＋φ）的一般正弦信号，若φ＝π／２或φ已知（但φ≠０），那么，抽样频率ｆｓ只需取二倍的ｆ０，即可由抽样序列ｘ（ｎ）重建ｘ（ｔ）；若φ未知，不论对实正弦还是复正弦，为保证ｘ（ｔ）的重建，抽样频率ｆｓ至少要取三倍的ｆ０；当用离散傅里叶变换（ＤＦＴ）对截短后的ｘ（ｎ）作频谱分析时，为防止泄漏，抽样频率ｆｓ应取信号频率ｆ０的整数倍，信号长度应包含整周期；此外，还分析了正弦信号抽样中的不确定性以及相应的解决办法。     

采用DLP的PMP系统中的莫尔效应及其对位相测量的影响

在采用数字光处理器(DLP)作为光栅投影系统的位相测量轮廓术(PMP)中，研究了莫尔效应产生的原理及其对位相测量结果的影响，DLP投射的光栅信号可视为对正弦模拟信号的抽样，CCD采集到的光栅信号又是对DLP投影信号的抽样，当DLP的核心部件DMD芯片和CCD图象传感器的空间频率满足一定条件时，CCD采集的图样将因为两次抽样过程产生莫尔条纹，通过对这两次抽样过程的分析，得到了莫尔条纹产生的条件和光强表达式，找出了N位相算法中莫尔条纹引起的位相误差规律，给出了数字模拟实验结果。     

序贯抽样决策中的抽样数量

序贯抽样决策的核心问题是抽样数量的多少及其样本单元所反映的动态信息特征，笔提出了“基本抽样数（nmin)”概念，并分别就不同的序贯抽样决策模型给出了相应的计算公式。在林间抽样决策中，预定的抽样数(n）应大于或等于nmin（即n≥nmin），以避免序贯抽样曲线方程对判断结果影响，结合最大抽样数nmax，两确定了序贯抽样曲线方程的适应范围。     

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.