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1.
根据Biot多孔媒质声学理论及多孔媒质界面边界条件,导出了腔内为流体的柱状多孔媒质结构中任意周向波数声导波的广义色散方程。数值计算了其中轴对称和非轴对称声导波的色散特性,考察了流体多孔媒质界面特性及多孔媒质中慢纵波对声导波色散特性的影响。结果表明,利用Biot多孔媒质声传播模型和多孔媒质界面边界条件,可以求得柱状多孔媒质结构中任意周向波数声导波的色散特性  相似文献   

2.
根据Biot多孔媒质声学理论及多孔媒质界面边界条件,导出了腔内为流体的柱状多孔媒质结构中任意周向波数声导波的广义散方程。数值计算了其中轴对称和非轴对称声导波的色散特性,考察了流体-多孔媒质界面特性及多媒体质中慢纵波对声导波色散特性的影响。结果表明,利用Biot多孔媒体质传播模型和多孔媒质界面边界条件,可以求得柱状多孔媒质结构中任意周向波数声导波的色散特性。  相似文献   

3.
本文利用部分相干光的张量ABCD定律研究了部分相干的非轴对称高斯-谢尔模(GSM)光束在光腔内的频谱演化特性,得到了解析的表达式.这一方法避免了已往处理部分相干光频谱变化时采用数值积分所带来的计算量太大的问题,并且适用于任意的傍轴光学系统.结果表明非轴对称GSM光束的相对频移与部分相干光本身的参数、振荡的次数以及光腔的参数有关,并且随着横向尺度的增加,频谱从红移逐步过渡到蓝移.  相似文献   

4.
本文研究涡旋流动中轴对称和非轴对称扰动的相互作用。在无粘、不可压涡旋流动中引进轴对称和非轴对称扰动,将扰动速度展开成傅立叶级数,代入到无粘、不可压流基本方程组中,使用多重尺度摄动方法,获得轴对称和非轴对称弱非线性扰动波振幅的调幅过程所满足的联立方程组。数值计算表明,在满足轴对称扰动和非轴对称扰动耦合的条件下,可以得到具有孤立子性质的轴对称扰动和非轴对称扰动。最后简要地从能量观点讨论了轴对称和非轴对称扰动的干扰机理。  相似文献   

5.
为探索非轴对称静叶在压气机中应用的可行性及其对畸变流场的改善作用,采用非定常数值模拟方法,研究非轴对称静叶对均匀和畸变进口条件下压气机性能的影响,并对流场结构进行分析.结果表明:非轴对称静叶可以改善静叶端区流动,降低损失;畸变条件下,非轴对称压气机最高效率和压比高于轴对称压气机;非轴对称压气机稳定裕度较原型压气机有所提升.  相似文献   

6.
非轴对称端壁成型及其对叶栅损失影响的数值研究   总被引:12,自引:0,他引:12  
根据叶栅非轴对称端壁成型的基本原理,探讨了非轴对称端壁成型的技术,利用三角函数构建了叶栅非轴对称端壁的型面,对5种不同端壁的叶栅进行了数值模拟,并采用三维时均可压缩N-S方程组求解方法,对构建的非轴对称端壁的跨音速直列叶栅进行了数值研究.结果表明:采用非轴对称端壁可有效降低叶栅二次流损失,所建立的非轴对称端壁成型方法效果比较明显;成型过程中单峰幅值控制函数要明显优于双峰函数,单峰幅值控制函数中最大幅值约占5%叶高为宜,此时计算结果显示在叶栅128%轴向弦长处总压损失降低了约4.7%。  相似文献   

7.
本文针对非轴对称拔制金属管材三维速度场分析的问题,通过复变共形映射的理论,将非轴对称拔制问题映射成轴对称问题,继而以逆映射变换,将此轴对称问题返回到非轴对称管件拔制塑性变形速度场及空拔管壁厚均化的问题求解,提出了非轴对称管件三维速度场的二次映射变换法。  相似文献   

8.
小展弦比叶栅非轴对称端壁造型及气动性能的数值研究   总被引:1,自引:0,他引:1  
提出了基于双控制型线的非轴对称端壁造型新方法,并在某小展弦比叶栅的上下端壁上完成了非轴对称端壁造型设计.采用数值求解Reynolds-Averaged Navier-Stokes(RANS)和考虑转捩模型的SST湍流模型对轴对称端壁原始叶栅和非轴对称端壁叶栅进行了详细的流场特性分析,结果表明:所提方法可以有效减少进入叶栅通道涡的低能流体,从而抑制了通道涡的发展,减少了二次流损失.由于叶栅展弦比较小,所以非轴对称端壁会影响到整个流场,使得出口气流角在整个叶高范围内有所增大,中叶展处叶片负荷下降,型面损失减少.与轴对称端壁原始叶栅相比,非轴对称端壁叶栅效率提高了0.22%,从而验证了所提方法的有效性.  相似文献   

9.
透平叶栅非轴对称端壁优化设计   总被引:1,自引:0,他引:1  
为减小透平叶栅二次流损失、提高气动效率,建立了结合透平叶栅非轴对称端壁造型双控制型线参数化方法、全局优化自适应差分进化算法和基于Reynolds-Averaged Navier-Stokes(RANS)方程求解技术的叶栅气动性能评价方法于一体的透平叶栅非轴对称端壁优化设计体系,同时验证了全局优化自适应差分进化算法和透平叶栅气动性能评价方法的可靠性和准确性。以透平叶栅总压恢复系数最大化为优化目标,在出口气流角和质量流量的约束及叶栅非轴对称端壁三维参数化控制点共20个设计变量下,完成了透平叶栅非轴对称端壁造型优化设计。研究结果表明,优化后得到的非轴对称端壁造型可有效减少透平叶栅的二次流损失,使叶栅总压恢复系数提高0.25%,证明所提出的设计体系是有效的,可为透平叶栅非轴对称端壁优化提供设计工具。  相似文献   

10.
用ESR(ElectronSpinResonance)波谱研究(C2H5)4NB10H10Cu和(CH3)4NB12H12Cu的结构和化学键.结果表明该系列化合物中11B和14N核与Cu2+之间不是以共价键或者离子键形式直接连接,很可能存在着CuHB桥键,但Cu2+和1H之间的作用比较弱.(CH3)4NB12H12Cu中Cu2+位于B12H122-轴对称性配位场中,因而有较高的对称性和稳定性;(C2H5)4NB10H10Cu中Cu2+位于B10H102-非轴对称性配位场,并且Cu2+彼此之间相距较近  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
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.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
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。  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

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