定常的Navier-Stokes方程的Petrov-Galerkin最小二乘二重网格有限元法

提出了定常的Navier-Stokes方程的Petrov-Galerkin最小二乘二重网格有限元法.该方法是在粗网格有限元空间X＾H上解一个小的非线性问题,同时在细网格有限元空间X＾h(h<相似文献   

薛定谔方程向后欧拉全离散两网格混合有限元方法

针对二维依赖于时间的线性薛定谔方程,在空间方向采用混合有限元方法,时间方向利用向后欧拉方法,得到一种全离散混合有限元格式.为了将薛定谔方程耦合的实部和虚部解耦,提出了一种全离散混合有限元的两网格算法,将方程在细网格上的求解问题,简化为在一个相对更粗的网格上求解原问题以及在细网格上求解两个泊松方程,从而减小计算工作量,节...     

求解不可压Navier-Stokes方程的一种高效两水平方法

提出了一种基于Arrow-Hurwicz(A-H)方法的两水平方法(以下简称m-A-H-1-Oseen方法)来求解不可压Navier-Stokes(N-S)方程.首先在粗网格上采用A-H方法求解不可压N-S方程,得到粗网格上的数值解.然后在细网格上利用粗网格上的数值解求解原方程线性化的Oseen格式,由此获得所需的两水平方法.对该方法的收敛性进行了系统理论分析.     

混合网格化学非平衡绕流通量分裂格式及并行算法

讨论了非结构混合网格上的二阶VanLeer逆风矢通量分裂格式,并将其应用于三维高超声速化学非平衡粘性流场的并行计算.高超声速绕流的复杂性要求对N-S方程求解的数值模拟方法应具有较高的计算精度及效率.我们针对混合网格上的有限体积格心格式,引入辅助点方法建立了具有空间二阶精度的VanLeer逆风矢通量分裂格式,提高了数值格式的模拟精度,并采用分布式并行化计算技术用以提高计算效率.粘性通量的计算采用中心格式,化学非平衡动力学模型为7组元空气反应模型,采用考虑了化学反应特征时间的当地时间步长显式Runge-Kutta时间推进格式.对三维双椭球外形的高超声速粘性流场进行了并行计算,获得满意的结果.     

四边形网上双曲型方程的有限体积元法

有限体积元法已引起国内外学者和专家的广泛关注,该方法与有限元方法有着相同的收敛阶,具有计算简单,保持物理量守恒性等优点.讨论一类双曲型方程在四边形网上的有限体积元法,在四边形网格单元满足h2拟平行四边形条件下,给出了双曲型方程半离散有限体积元格式下最优的H1模和L2模误差估计以及两个全离散有限体积元格式下的误差估计.     

一维非线性对流扩散方程特征有限元的两重网格算法

针对一维非线性对流扩散方程，构造了特征有限元两重网格算法。该算法只需要在粗网格上进行非线性迭代运算，而在所需要求解的细网格上进行一次线性运算即可。对于非线性对流占优扩散方程，不仅可以消除因对流占优项引起的数值振荡现象，更重要的是可以加快收敛速度、提高计算效率。误差估计表明，只要选取粗网格步长与细网格步长的平方根同阶，就可以使两重网格解与有限元解保持同样的计算精度。     

非线性双曲型方程的混合有限元两层网格算法

针对一类非线性双曲型方程, 利用混合有限元法,构造了1种混合有限元两层网格算法, 给出了两网格方法的误差分析. 结果表明, 当两层网格算法所选取的粗网格和细网格步长满足H=б(h^1/2)时,能获得渐近最优的离散逼近解. 并用数值例子验证了该混合有限元两层网格算法的有效性.     

Cahn-Hilliard方程的时间双层网格混合有限元方法

针对数值求解Cahn-Hilliard方程时非线性项引起的时间耗时问题,提出了时间双层网格混合有限元方法.首先,在时间粗网格上,通过非线性牛顿迭代方法求解非线性混合有限元系统,其中空间离散采用混合有限元方法,时间离散采用隐式欧拉格式;其次,基于初始迭代数值解和拉格朗日插值公式,在时间细网格上求解线性混合有限元系统;最后,分析了该方法的稳定性和误差估计,并通过数值算例进行验证.结果表明,与传统的混合有限元方法相比,该方法可以节省计算时间.     

改进格式的组合网格法

针对组合网格法在求解特殊类型的工程问题时求得数值解精度低的缺陷,提出一个改进计算格式的组合网格法.粗细两套网格都是在各自区域上单独剖分,两套网格互不影响,在粗网格上达到粗网格的精度,在细网格上达到细网格的精度.该方法的网格剖分为粗网格和细网格,能够大大提高数值解的精确度.     

定常不可压缩NS方程的子格粘性非协调有限元方法

作者将子格粘性法和非协调有限元方法相结合,应用到定常不可压缩NS方程,并采用C-R元建立了两种子格粘性非协调有限元格式,然后对其进行了理论分析.数值实验结果表明,子格粘性法与通常的Galerkin混合有限元相比,在高雷诺数时仍然具有较好的稳定性,在粗网格上能达到较高的精度.     

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.     

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.     

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.