变速移动载荷激励浮冰层的位移响应特性

基于弹性薄板假设和势流理论,利用薄板振动微分方程以及运动学边界条件建立了变速移动载荷激励浮冰层位移响应的理论计算模型.采用傅里叶-拉普拉斯变换的方法进行求解,通过数值计算获得浮冰层的位移响应.将退化到匀速情况的计算结果与实冰实验数据进行比较,发现临界速度的值以及临界速度下冰层位移响应的波形特征与实验结果相一致;此外,以匀加速载荷为例,通过改变加速方式、冰厚、水深等参数,分析了不同加速方式下浮冰层位移响应的特征,明确了水深、冰厚等因素对浮冰层位移响应的影响,揭示了移动载荷加速度与破冰效率间的关系.     

系列移动荷载下周期性弹性支撑连续梁的共振及消振效应

基于Fourier变换、系列Fourier变换及传递矩阵方法,研究了移动荷载列作用下周期性弹性支撑连续梁的共振及消振效应。通过Fourier变换和系列Fourier变换,把单个移动载荷所引起的动力响应表示为响应函数沿代表跨的积分。利用梁和弹性支撑处的传递矩阵,建立了周期性弹性支撑连续梁的响应函数和特征方程。根据叠加原理并利用单个移动载荷的解,得出了等间距移动载荷列作用下周期性弹性支撑连续梁的动力响应表达式。根据单个移动载荷引起梁的频域响应,建立了周期性弹性支撑连续梁在等间距移动载荷列作用下的共振和消振条件。计算结果表明:当移动载荷列的速度及间距符合共振条件时,将会发生共振效应;当符合消振条件时,将会发生消振效应。     

基于FLAC3D的移动荷载作用下基坑结构响应的分析

文章分析了深基坑支护结构在移动荷载作用下的动力响应问题,建立了相应的有限元实体模型,通过FLAC3D软件进行动力响应分析,并讨论了深基坑结构在不同移动荷载速度作用下的位移和应力变化;计算结果表明,速度大小对深基坑支护结构的动力位移和内力响应有较大影响,并为此类结构的设计提供参考依据.     

匀速移动载荷激励浮冰层大幅响应的临界速度

从弹性薄板振动微分方程和势流理论出发,基于二维傅里叶积分变换方法,建立了匀速移动载荷作用于弹性浮冰层的位移响应和临界速度的理论计算模型.通过数值计算获得了浮冰层的位移响应和移动载荷的临界速度,分析了水深、冰厚、载荷强度、载荷半径等因素对位移响应和临界速度的影响.计算结果表明:基于奇点法和能量法获得的临界速度具有很好的一致性;冰层的位移变形随载荷速度的增加先增后减,在临界速度时达到最大;水深的增加导致临界速度和位移变形增加,冰层厚度的增加导致临界速度增加,但位移变形减小;移动载荷强度的增大或载荷半径的减小虽然使冰层的位移变形增加,但对临界速度的影响很小.     

移动载荷作用下周期性高架桥有限元模型

提出一种移动荷载作用下周期性高架桥(PV)动力响应的有限元计算方法;首先对PV在力学计算方法上进行简化并建立模型;根据Fourier变换法,建立移动载荷作用下PV频率波数域内的表达式;结合PV代表跨梁和墩的有限元方程,以及各跨梁-梁-墩连接处的连接条件及PV的周期性条件,得出PV受频率波数域内单位简谐荷载作用下的有限元方程;求解该方程可得PV在频率波数域内的动力响应,对此响应进行Fourier逆变换,可得PV在时空域的动力响应;基于所建立的有限元模型,进行数值分析。结果表明,移动荷载的速度会影响PV频域内响应的峰值个数,速度增大,峰值个数会减少;随着载荷速度的增大,PV时域内的响应呈现类似冲击波特征。     

解析解下沥青路面动力响应分析及应用

根据沥青路面不仅具有弹性而且具有黏滞性的特点,将沥青路面简化为支撑在黏弹性地基上的黏弹性梁.建立了移动载荷作用下粱的动力学模型并求得了其解析解.通过对解析解进行数值计算,研究了车辆速度、轴载和面层黏性阻尼等主要参数对路面动力响应的影响.结果表明,沥青路面动力响应随着车辆速度的减小而增大,与轴载成线性比例增加关系,并随着面层黏性阻尼的增大而减小.     

粉砂地层中列车载荷对曲线隧道沉降的影响

为揭示粉砂土层中列车移动载荷作用下曲线隧道沉降规律,采用MIDAS数值模拟软件,对地铁列车载荷进行动态模拟,以郑州地铁一号线一期工程为背景,对隧道结构进行现场实测,将作用在轨道上的载荷分解成列车轴重引起的竖向力、横向力以及轨道超高引起的离心力,研究列车移动载荷对不同曲线半径和车速条件下隧道周围土层动力响应和沉降的影响.研究结果表明:粉砂土层中列车振动载荷对曲线隧道周围土层的影响主要在隧道底部0～15m内;隧道下方土层动力响应和长期累积沉降随着隧道转弯半径的增加而减小;列车运行速度的提升导致隧道下方土体动力响应增加71.4%,与之对应的长期累积沉降值降低6.4%.研究结论总结了列车载荷对隧道的沉降影响规律,为盾构隧道工程施工提供参考与建议.     

匀加速行驶车辆与桥梁耦合振动的分析方法

为了分析匀加速行驶车辆与桥梁的相互耦合作用,在重点考虑了移动车辆的牵连惯性力及其行车加速度对桥梁竖向振动作用的条件下,建立了匀加速移动的四自由度车辆模型与桥梁耦合振动微分方程;利用有限元的求解方法,在匀加速移动车辆的初速度和加速度2个运动参数变化情况下,得出了桥梁的动挠度响应规律。数值分析表明:车辆初速度和行车加速度对桥梁动力系数影响较大;随初速度的增大,桥梁动力系数增大;随加速度的增大,桥梁动力系数先增大、后减小,存在一个最值区域。     

砰击载荷作用下板结构动力学响应的参数分析

对板结构在砰击这一瞬态载荷作用下的动力响应进行参数分析,在进行动力响应计算时,考虑材料的弹塑性,分析的参数有：压力峰值、附加质量、结构刚度、载荷作用时间和连续砰击次数,通过有限元方法进行分析,为船舶设计提供有用的建议。     

龙卷风作用下大跨度桥梁车-轨-桥耦合振动及行车安全性

为研究龙卷风作用下大跨度桥梁车-轨-桥系统动力响应及行车安全性,首先以Kou-wen三维模型模拟龙卷风速度场,基于准定常理论确定了移动龙卷风作用下车辆和桥梁风荷载时程. 然后,分别采用多体系统动力学和有限元理论建立列车和轨道-桥梁子系统动力方程,基于轮轨空间非线性接触建立风-车-轨-桥系统动力方程,并采用分离迭代法求解系统动力响应. 数值算例中,以某公路铁路两用斜拉桥为研究对象,通过风洞试验和CFD数值模拟确定车辆和桥梁气动力系数,分析了龙卷风移动路径、强度等级和行车速度对车-桥系统动力响应及列车行车安全性的影响. 结果表明：桥梁竖向振动响应比横向显著,且龙卷风竖向风速对桥梁竖向位移起控制作用 . 当车辆经过风荷载最大位置时,车辆的横向和竖向振动响应均达到最大值,且车辆动力响应受龙卷风荷载和桥梁动力响应共同影响. EF1级和EF1.3级龙卷风作用下,列车安全通过的车速阈值分别为180 km/h和114 km/h.     

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.