一类三次微分系统的时间可逆与中心问题

利用时间可逆系统的性质和Regular Chain方法得到一类三次多项式微分系统在线性对合下为时间可逆系统的充要条件,此条件保证了原点必为该系统的中心.     

线性广义系统的最优控制

研究线性广义系统的最优控制问题·引入线性广义系统的Riccati方程,给出了该系统在二次性能指标下存在线性最优控制的充分必要条件·     

Banach 空间的p-弱近似性质

给出了Banach空间的$p$-\!\!弱近似性质和$p$-\!\!有界弱近似性质的定义, 获得了这些性质的一些刻画. 利用这些刻画证明了如果一个Banach空间$X$ 的对偶空间$X^{*}$有$p$-\!\!弱近似性质 (或$p$-\!\!有界弱近似性质), 则$X$ 有$p$-\!\!弱近似性质 (或$p$-\!\!有界弱近似性质), 在一般情况下反之不成立.     

具无界恢复力Duffing方程Mather集的存在性

引进合适的作用-角变量变换并结合新的估计方法,对Duffing方程的Poincaré映射应用推广的Aubry-Mather定理,获得了一类具无界恢复力的Duffing方程Aubry-Mather集存在的充分条件,推广和改进了已有的结果.     

一类不对称Duffing方程的Aubry-Mather集

利用推广的Aubry-Mather定理,获得了一类不对称Duffing方程Aubry-Mather集的存在性,推广和改进了已有的一些结果。     

一类复杂非线性系统的模糊控制稳定性分析

研究一类能够用离散动态模糊模型描述的复杂非线性系统的模糊控制稳定性问题·首先设计出PDC模糊控制器·然后利用区间系统理论,在带扰动系统二次稳定意义下给出了闭环系统渐近稳定的两个充分条件,并且后一稳定性条件被转化为线性矩阵不等式可解性问题·仿真结果证明了此方法的有效性·     

允许 Green 函数取零值情形下 Neumann 问题的正解

本文研究了一类二阶非线性常微分方程Neumann边值问题 $$ \left\{\begin{array}{ll} y''+\ a(t)y=\lambda g(t)f(y),~~\ \ \ t\in [0,1],\\[2ex] \ y''(0)=\ y''(1)=0, \end{array} \right.\eqno $$正解的存在性,~其中~$\lambda$~是一个正参数,~$f$~在~$\infty$~处是超线性的且~$f$ 允许变号,此外与这一问题相关的Green 函数可以在某些点等于0. 主要结果的证明基于Krasnosel''skii不动点定理.     

具有时变不确定性的线性时滞系统的鲁棒H_∞性能分析

研究一类具有时变不确定性的线性时滞系统的鲁棒H∞性能,方法是采用仿射二次稳定概念把这类问题转化成线性矩阵不等式问题·与采用二次稳定概念相比,所得结果具有更小的保守性     

线性切换系统基于子系统的灵敏度分析

研究了一类线性切换系统的灵敏度·通过引入灵敏度参数,提出了一种新的线性切换系统的数学模型·指出灵敏度函数的求解,应首先求解一个灵敏度方程,并且通过灵敏度函数定义了线性切换系统基于子系统的灵敏度·在线性切换系统的分析中,灵敏度发挥着重要的参考作用·通过例子计算,验证了理论结果的正确性·     

区间广义系统的鲁棒H_∞控制

讨论了线性时不变区间广义系统基于状态反馈的鲁棒H∞控制问题·利用区间矩阵的一种等价描述形式,将所讨论的区间广义系统转换成一般的线性时不变不确定广义系统,给出了区间广义系统二次稳定且具有扰动衰减度γ及二次能稳定且具有扰动衰减度γ的概念,得到了该问题可解的充要条件是一个基于系统参数矩阵的矩阵不等式有满足广义约束的解,同时也给出了满足该问题的反馈矩阵的构造方法·     

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.     

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.     

The Analects and the Moment in Peking——The influence of a Confucian education system on the personality formation,the way of thinking and the fate of the main characters

0.Preface China has long been boasting of its colorful and immense culture which comprises of Taoism,Confucianism and Buddhism.The interwoven influence among the religions on Chinese way of thinking,on the nation＇s behavior in their social life throughout the long history is beyond list.