侧压式进气道自起动数值模拟

本文采用加速的方法,数值模拟了侧压式进气道自起动现象。研究结果表明低马赫数不起动的侧压式进气道通过加速可以实现自起动,此时的侧压式进气道流场总体性能与直接起动的进气道流场总体性能存在差异,使得直接起动的进气道有较高的总压恢复。     

超声速混压式进气道起动与质量吸除耦合设计

结合质量吸除方案,对超声速混压式进气道进行了起动耦合型面设计,并采用CFD数值模拟对进气道的总体性能进行了对比分析。研究结果表明该方案具有以下优点:1)可以提高进气道的总体性能;2)可以解决低马赫数下超声速混压式进气道的起动问题;3)可以改善高马赫数下进气道的气流分离特性。为大空域、宽马赫数工作的超声速进气道的设计提供参考。     

超声速几何可调二元进气道设计优化算法研究

为满足超声速二元进气道的气动性能和宽马赫数工作的要求,探索了一种气流角可调式进气道的方案,采用区间搜索优化算法,完成了设计马赫数3.5,起动马赫数2.0的几何可调进气道的最优设计。通过CFD数值结果验证了准确性。结果表明:1与设计值相比,最优设计的几何可调进气道在所有工作马赫数条件下的总体性能均得到较大提升;2通过优化算法估算得到的进气道的性能参数与CFD数值结果相差不大。     

双S弯进气道锤激波动态特性研究

发动机喘振产生的瞬时高压引起的进气道内锤激波载荷是飞机进气道结构强度设计的关键因素之一。通过对飞行器进行内外流一体化非定常三维数值计算,分析双S弯进气道内锤激波三维流场非定常特性的演化过程,研究了不同马赫数,不同超压比对双S弯进气道锤激波载荷的影响。研究表明：锤激波经过进气道弯道时,弯道外侧流场压力远大于内侧;锤激波离开进气道入口后,进气道内流场经过数个周期逐渐恢复至初始状态;相同进气道反压时,来流马赫数越小,锤激波在进气道内部传播速度越快,且进气道内部压力系数峰值越大;相同来流马赫数下,随着超压比的增大,锤激波在进气道内部传播速度加快,进气道内部压力系数峰值增大。     

M4超声速进气道起动特性研究

针对亚燃冲压发动机进气道的起动问题进行了研究,提出了影响该问题的关键因素为设计状态内压缩段进口马赫数M2,d和喉道马赫数Mt,d。通过对一系列二元超声速定几何进气道的流动进行一维流路分析和CFD数值模拟分析,总结了不同M2,d和Mt,d对进气道起动特性的影响规律。     

RBCC飞行器变结构进气道方案研究

火箭基组合动力循环(RBCC,Rocket Based Combined Cycle)飞行器的飞行速域宽、距离远,这就要求飞行器在整个飞行包络内,其推进系统不仅在设计点具有良好的性能,在非设计点时也要求能正常工作。本文以一种RBCC飞行器为研究对象,计算不同马赫数条件下动力系统进气道的性能,在此基础上提出一种进气道的变形方案。结果表明,本文所设计的变几何进气道方案,能够使得组合动力发动机在工作段满足不同的推力需求,提高了发动机的效率。     

涡轮基组合循环发动机进气道设计

采用等激波强度的方法,考虑进气道的气动性能和进气道前体斜板的调节规律。对高超声速涡轮基组合循环发动机的二维混压式几何可调进气道的设计进行了探索。控制进气道喉部出口马赫数的大小,给出了三斜板内外混合压缩进气道设计点的几何尺寸和非设计点的斜板调节规律。运用二维CFD数值计算手段,通过求解欧拉方程,对所设计进气道在不同飞行条件下的流场进行了计算。计算表明,设计的进气道结构简单,附加阻力小,总压恢复系数高,低速起动性能好,调节规律容易实现。     

火箭基组合动力循环飞行器变结构进气道方案研究

火箭基组合动力循环(RBCC,rocket based combined cycle)飞行器的飞行速域宽、距离远,要求飞行器在整个飞行包络内,其推进系统不仅在设计点具有良好的性能,在非设计点时也要求能正常工作。以一种RBCC飞行器为研究对象,计算不同马赫数条件下动力系统进气道的性能,在此基础上提出一种进气道的变形方案。结果表明,所设计的变几何进气道方案,能够使得组合动力发动机在工作段满足不同的推力需求,提高了发动机的效率。     

混压式超声速进气道喉道长度的设计与数值研究

为了提高定几何混压式超声速进气道的性能,对冲压发动机轴对称混压式超声速进气道进行了研究,并重点研究了喉道长度的设计及激波附面层干扰对进气道性能的影响.数值计算结果表明:在进气道总长度一定的条件下,喉道长度小于激波链长度的设计对进气道的总性能更有利.在计算马赫数分别为3.5和4.0的条件下,将喉道长高比为3.75和10.0的进气道相比,其总压恢复系数分别增加了6.15%和5.04%;对于长度一定的进气道,喉道越长,则扩张段越短,达到同样扩张比的扩张角就越大.因此,对于设计马赫数为4.0的进气道,取喉道长高比为3.75时,进气道的总压恢复系数最高,抗反压能力也较强,该结果可为定几何混压式超声速进气道的设计提供参考.     

二维高超声速进气道内激波-边界层相互作用

在多级压缩二维高超声速进气道中,激波边界层相互作用在前后两级压缩面交界的折角处会诱发壁面流动的分离,导致分离泡的产生.压缩面折角位置产生的激波与唇口处边界层相互作用,同样会诱发明显的壁面流动分离.这些分离现象均存在较为明显的动态特征和空间结构上的不稳定性,对进气道内流场及起动性能存在一定的影响.这里主要利用改进的高速纹影系统对二维二级压缩进气道内的流动结构进行观测及分析,揭示了分离流动的细节结构以及演化过程.在此基础上,采用改变壁面粗糙度以促进边界层转捩、壁面添加扰流器促进边界层内掺混流动等措施改变边界层流动状况,观察边界层控制对分离流动的影响,并取得了初步的结果.     

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.