台阶开孔式缓冲结构对隧道气动效应分析

随着列车速度的不断提升,列车由明线驶入隧道所引发的微气压波问题变得日益突出,有关研究表明：组合型式缓冲结构较单一型式缓冲结构能更好的缓解微气压波的影响,为了进一步减缓微气压波对隧道周边环境的影响,本文提出了台阶开孔式组合型缓冲结构。基于 两方程紊流模型,运用数值模拟的方法,从开孔距离、开孔率、开孔数量、开孔位置四个方面进行研究,对列车驶入隧道所引起的初始压缩波压力和压力梯度值进行具体分析,得出优化设计参数。台阶开孔式缓冲结构对初始压缩波压力最大值的影响较小,最大压力值差值保持在10Pa内,但对初始压缩波压力梯度值影响较大。当开孔距离为4m、开孔率α为36％、开孔数量为2孔、开孔位置为顶部开孔时,为最优工况,对压力梯度的减缓效果达到了60.14％。     

交叉开口型缓冲结构对隧道微压波的作用分析

针对高速铁路隧道空气动力学问题,现阶段研究的重点是找到更为有效减缓微压波的途径。采用数值分析中的动网格技术,对高速列车突进设置有非交叉开口型与交叉开口型缓冲结构的隧道进行数值模拟。研究结果表明:开口在减缓气动效应的作用上,会相互影响;修建适当的交叉开口型缓冲结构可以更有效地降低压力梯度峰值,在工程不变的情况下,降低率最大可达到8%;通过数值模拟对比分析,给出了两开口缓冲结构的最佳修建形式,并为交叉开口型缓冲结构的深入研究奠定了基础。     

基于特征线法的车隧压缩波演化数值分析

为研究压缩波沿隧道传播演化的影响规律,采用考虑压缩波惯性效应和壁面摩擦效应的一维特征线法,建立了压缩波沿隧道传播演化的数值模型,通过一维平面波方程与实车测试两种方法共同验证了该模型的准确性。针对波前形状、车身波等、压力幅值关键因素,研究了初始压缩波沿隧道传播时,最大压力梯度的变化规律。在此基础上,进一步探讨分析了摩擦与气室阵列共同作用对压缩波波前演化的影响以及壁面摩擦的作用机理。结果表明：初始压缩波波形相同时,压缩波最大压力梯度随波前幅值的增大而增大;不同波形的初始压缩波沿隧道的演化规律不完全相同,但列车车身进入隧道所产生的车身波并不会影响压缩波波前的最大压力梯度;考虑壁面摩擦后,气室阵列对压缩波最大压力梯度的缓解效果有了进一步提高,壁面摩擦越大,缓解效果越显著。     

风井缓冲结构参数对地铁列车气动性能的影响

随着地铁列车速度不断提升,列车高速通过隧道风井(缓冲结构)时隧道内交变压力显著增加,会对列车内乘客造成严重影响。本文采用滑移网格方法,通过模拟地铁列车由车站开始加速并以最大速度通过隧道风井缓冲结构过程的气动性能,分析风井缓冲结构的参数对隧道内交变压力的影响规律。研究结果表明：列车表面压力数值计算结果与实车试验结果较吻合。风井缓冲结构可以有效减小列车通过风井时的压力变化幅值,风井前缓冲结构对列车通过时的压力变化率影响较大,而对列车压力变化幅值影响较小,风井后缓冲结构可以有效减缓列车通过风井过程的压力突变。随着缓冲结构横截面积增大,列车通过风井时的压力变化幅值呈减小趋势,但不同缓冲结构下列车表面压力差异较小。当缓冲结构总长度一定时,随着风井后缓冲结构长度增加,列车表面压力变化幅值呈减小趋势;当风井后缓冲结构的长度由0 m增加至50 m时,头车表面压力幅值减小21.5%。     

帽檐斜切式洞门斜率对隧道气动性能的影响

基于三维、可压缩、非定常N-S方程和k-ε双方程湍流模型,对不同斜切斜率帽檐斜切式洞门下的隧道空气动力效应进行数值模拟,得到高速列车过隧道时车体表面、隧道壁面监测点的瞬变压力及隧道出口微气压波.研究结果表明:帽檐斜切式隧道洞门的斜切斜率对车体表面和隧道壁面监测点的瞬变压力变化基本无影响,最大相差在5％左右;随着斜切斜率的减小,初始压缩波由零点上升到峰值所用时问减缓,压力梯度最大值减小;斜切斜率从1∶1降至1∶2时, 隧道出口20 m处微气压波幅值由66 Pa降至54 Pa,降幅达18.2％,可见减小洞门结构的斜切斜率,可改善隧道口微气压波.数值计算结果与动模型试验结果吻合较好,仅幅值略有差异,最大相差在5％以下.     

缓冲结构对隧道口微气压波的影响

为有效缓解微气压波对隧道周围环境的影响,设置合理的缓冲结构,采用数值模拟计算和动模型模拟实验相结合的方法,对列车通过隧道引发的压力变化、微气压波和不同形式的缓冲结构进行研究.研究结果表明:对任一类型缓冲结构,其结构长度和入口断面积之间均存在固定的最佳匹配关系,即对断面扩大无开口型缓冲结构,当缓冲结构长度分别为1.0D,2.0D和3.0D(D为隧道等效直径)时,对应的最佳入口断面积分别为1.8S,1.9S和1.8S(S为隧道断面面积),微气压波幅值分别减小46.7%,55.3%和52.8%;对线性喇叭型缓冲结构,当缓冲结构长度分别为1.5D,2.0D和3.0D时,对应的最佳入口断面积分别为2.5S,2.4S和2.7S,微气压波幅值分别减小59.4%,64.2%和71.6%.     

隧道结构对高速列车穿行过程气动特性的影响

以CRH2型高速列车穿行隧道过程的气动特性为研究对象,建立了列车模型及具有不同缓冲结构、不同阻塞比的隧道计算模型,并与相同工况下的模型实验进行对比,验证了仿真模型的可行性.以kε-湍流模型为基础,对高速列车以不同速度进入具有不同缓冲结构、不同阻塞比的隧道时的外流场进行了仿真模拟.分析了列车在进入隧道时压缩波的产生机理,得到了列车表面风口在车体进入隧道过程中的压力波动情况.仿真结果表明:隧道缓冲结构的缓冲性能按抛物线型、线性、不连续性的顺序依次减小;压力值随阻塞比增大而线性减小.由此提出了减小列车进入隧道时表面压力波动的方法.     

基于正交试验的隧道洞口缓冲结构参数优化

为了优化高速铁路隧道洞口缓冲结构参数,基于正交试验,利用FLUENT中三维、可压缩、粘性、湍流模型完成了4因素4水平共16种组合工况的数值模拟.试验中着重考察了各因素、水平组合对压力梯度降低率的影响.研究结果表明:正交试验能有效减少试验次数且不降低试验精度;各因素对组合式缓冲结构缓冲效果影响的主次顺序依次为开口尾部距隧道洞口距离、开口率、开口距缓冲结构入口距离、扩大断面与隧道断面积之比;在试验范围内给出了各影响因素的最优组合参数.     

基于实车试验的高速列车隧道压力波影响因素

搭建列车空气动力学在线实车高精测试平台,对列车通过隧道及隧道交会工况下的压力波特性进行实车测试;探究运行速度、隧道长度、阻塞比、编组长度、交会位置等因素对隧道压力波的影响规律;根据隧道内压缩波、膨胀波在隧道内传播、反射、叠加的原理,推导出隧道通过及隧道交会工况下,最不利单线隧道长度、最不利双线隧道长度、最不利交会位置、最不利编组长度等计算公式。研究结果表明:车体表面压力变化幅值与列车速度的平方成正比;车内压力幅值与列车速度的n次方成正比,n的范围为1.3~1.8,n随着隧道长度的变化而变化;研究结果可为高速列车在隧道内运行时的安全性指标提供了压力波评判依据。     

高速铁路并联隧道横通道对隧道内压力变化的影响

给出了高速列车穿越横通道高速铁路并联隧道时压力变化的三维非定常黏性流场数值模拟过程,研究了两条并联隧道横通道的面积变化、位置变化和斜交方式对并联隧道及横通道内压力变化的影响规律.计算结果表明:并联隧道横通道的存在,使得隧道内压力变化的最大值降低,隧道横通道断面积越大,则最大压力梯度的降低率越小,当横通道的断面积与隧道断面积之比为0.3左右时,其降低隧道中测点的最大压力及压力梯度的效果最好;横通道对隧道的降压效果与隧道交叉方式有关,横通道与隧道的斜交方式为正交,且正交角度控制在60°左右时,横通道对隧道内的降压效果比较好.对比分析表明,当并联隧道内的横通道、竖井及避洞在隧道内的位置、断面积、长度及与隧道的斜交角度相同时,竖井的降压效果最好,横通道次之,避洞的降压效果最差.     

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.