考虑覆盖率下时差式超声流量计的平面声道模型

为考察时差式超声流量计的声道覆盖率、布置方式对测量结果准确性的影响,对立体声道的平面声道模型进行了特性分析,推导出不同覆盖方式下覆盖面积的计算公式、声道段总数范围的确定公式以及声道段中心线至管道横截面中心距离的计算公式,并进行平面声道模型参数的设计.实例计算结果表明,文中提出的时差式超声流量计立体声道的平面声道模型计算方法是有效的.     

时差式超声流量计立体多声道模型设计

针对当前多声道时差式超声流量计空间对称式声道结构声道覆盖率较低,对不规则流场适应力较弱等问题,提出了立体多声道模型设计理论.推导出了满足期望覆盖率下的最少声道段数、各声道段与管道中心距离、声道数目及平面模型组合排列数量、单一声道的平面模型相邻声道段夹角的计算公式;进行了多声道拓扑结构设计;最后进行了算例设计和样机生产.实例计算与应用表明,文中提出的时差式超声流量计立体多声道模型设计方法具有可行性、先进性和实用性的特点.     

多声道超声气体流量计的建模与仿真

基于时差式超声流量计测量原理和Gauss-Legendre数值积分方法，建立了多声道超声气体流量计的数学模型．在建模过程中，根据瞬时流速以流速分布函数按面积积分的公式，推导出在弦向声道处的平均流速按声线积分的表达式，然后推导出在弦向声道处的平均流速加权求和的瞬时流速公式；应用Legendre多项式求解出高斯节点值和加权系数，即确定了各个声道的分布位置．以四声道交叉布置方式的超声气体流量计为例，通过Matlab仿真与误差分析，结果表明：在考虑流速分布的影响下，模型的测量误差不大于0．1％，验证了模型的正确性，因而多声道超声气体流量计完全能满足油气、天然气等气体在输送和分配计量中的精度要求．     

单弯头安装条件对内锥流量计性能影响的仿真研究

为获取上游弯头安装条件对内锥流量计的性能影响和所需的最短直管段长度,应用计算流体动力学数值仿真,对100 mm口径、等效直径比0.45/0.65/0.85的内锥流量计开展了上游单90°弯头的仿真研究。仿真介质为常温水,雷诺数范围,0.498×10~5～4.98×10~5,研究方案分基线和上游单90°弯头两类,共15组。利用平均流出系数相对误差及附加不确定度作为安装条件的主要评价标准,给出了上游单个90°弯头的直管段长度,并与国外研究结论作了比较。     

速度分布对气体超声流量计声传播规律的影响

气体超声流量计广泛应用于天然气贸易计量,在实际工业现场,由于流态和流速的不同,使得超声波传播特性呈现不同的规律.为了研究这一规律的变化特征,文中提出了一种基于COMSOL仿真的射线追踪方法来模拟单声道气体超声流量计的测量过程,并验证了该仿真方法的正确性.选取充分发展湍流和单弯头下游的速度分布为研究对象,以5个不同的速度点为入口流速,讨论超声波传播轨迹、传播时间、轨迹偏移量、声压分布等参数随流速、流态的变化规律,进而分析其对流量测量的影响,提出一种改善测量误差的修正方法,使测量误差最大降低约4%,,达到修正效果.     

多声道超声流量计在单弯管流场中的误差研究

通过单声道误差计算公式和误差统计权重系数的分析,得到多声道超声流量测量的误差计算公式,针对单弯管流场状况,计算不同安装角度下的对角式和平行式的多声道布置方式及不同安装位置的误差－角度关系及误差与管道粗糙度的关系。结果表明,每一种布置方式均有理论测量误差为零的安装角度,可通过选择合适的安装角度和位置来减小测量误差。若采用平行式的声道布置,则可通过选择0.4~0.6之间的弦位置来提高测量精度。     

同平面双弯头条件下A+K流量计前直管段长度的实验研究

A+K平衡流量计是针对航天飞机的主发动机液氧测量而设计发明的一种新型流量计,与其他的差压式流量计相比,这种新型流量计具有直管段短、精确度高、压损低、适用性广等优点.针对其直管段短的这一优点,对DN50、等效直径比分别为0.25与0.70以及DN100、等效直径比分别为0.25与0.65这4种结构的A+K平衡流量计在上游安装同平面90°双弯头时所需最短直管段长度进行了实验研究.通过对实验结果的定性和定量分析,最终给出上游安装同平面90°双弯头时A+K平衡流量计与双弯头之间所需的最短直管段长度.     

V锥差压流量计三维数值模拟与改进分析

应用计算流体力学方法对V锥差压流量计进行了数值模拟,分析了流量计内部的水利特性,并将数值模拟数据与试验数据进行了比较.数值模拟结果表明,V锥差压流量计的法兰对局部流场的影响较大,给试验测量带来较大误差.通过优化法兰的形状,可以改善法兰周围的扰动、提高测量点之间的压力差和提高测量精度.     

不同流场中均速管性能的实验

为了研究流场对均速管性能的影响,选取了菱形、delta形、子弹头形3种截面形状的均速管,分别在标准表法常压气体流量标准装置、负压法音速喷嘴流量标准装置以及风洞3种能够产生不同流场的装置中进行了实验研究.通过分析不同流场中均速管仪表系数、线性度及重复性等性能指标,发现3种截面形状均速管在同一流场中具有稳定的但数值各不相同的仪表系数、线性度及重复性;在不同流场中,仪表系数、线性度等性能变化较大,但其重复性在任何流场中均优于1.0%,在风洞产生的直匀流中优于0.2%,故均速管流量计在应用于不同流场中时,必须进行相应的标定,以获得较好的测量效果.     

圆柱齿轮流量计的误差特性

在对VC 0.2型圆柱齿轮流量计结构设计的基础上,综合考虑流量计泄漏、测量介质特性和流量计使用条件等影响流量计误差特性的因素,通过理论计算和仿真分析,得到了被测油液运动黏度、压力损失等因素以及不同使用条件对齿轮流量计精确度的影响.将理论计算、模型仿真结果与流量计出厂试验结果对比发现:利用理论计算的方法对流量计测量误差进行估计有一定局限性,只适用于高黏度油液测量;而模型仿真结果与流量计试验结果较符合,其相对误差在0.5%上下浮动.利用仿真模拟试验的方法得到了VC 0.2型圆柱齿轮流量计测量不同黏度油液时相对误差的具体数值.     

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.