波音777型飞机载荷下机场跑道实测动力响应

对丹佛国际机场跑道实测道面应变以及弯沉信号进行分析,研究了波音777型飞机在跑道上滑行时跑道的动力响应.结果表明:轮载离传感器越近,道面应变和弯沉测量值越大;横缝附近处弯沉有3个峰值点,对应飞机的3个轮轴,而纵缝板边中部和板中心处的弯沉呈半正弦形状,只有1个峰值;在横缝板边加载时,相邻的未加载板与基层间发生脱空;地基沉降占总沉降量的主要部分,3.05~6.10m范围内地基发生的非弹性变形非常小,可将3.05m深度以下的地基视为弹性地基;板横缝方向的应变表现为达到一定平台后有3次波动,而纵缝方向的应变表现为2次拉压转换,纵缝板边中部轮轴间的应变恢复显著,易发生疲劳破坏;板中部由于绑定效应引起中性面的偏移较大,而板边中性面偏移较小,故板边处可近似为脱离状态,板中心应考虑绑定效应.所得结论对机场跑道工程的优化设计与科学施工具有参考价值.     

基于实测数据的机场水泥道面变温效应分析

利用上海浦东国际机场"道面状态监测系统"实测的温度、应变和弯沉,分析了水泥道面温度以及温度作用下道面翘曲变形、弯沉、接缝传荷能力的变化.结果表明,土基和基层温度日变化较小,但季节性变化较大;道面板温度沿板厚分布呈非线性,下午时段更显著;全年正、负温度梯度占比基本相同,零温度梯度集中在7:00～10:00和19:00～22:00,且全年呈周期性;此外,在横缝(假缝)和纵缝(企口缝)板边中部以及板角,温度翘曲变形呈同步周期性变化,板角处最大,纵缝(企口缝)板边中部最小,向上(下)翘曲变形的全年最大值均分布在12月～1月(7月～8月);板中最大弯沉基本保持不变,而板角和横缝(假缝)板边中部最大弯沉日变化和季节性变化显著;假缝和企口缝的传荷能力随平均温度的增大而增大,具有良好的二次曲线关系.建议在道面设计和评价中考虑温度作用的影响.     

公路飞机跑道水泥混凝土道面静载承载能力研究

基于弹性半空间地基模型,对公路飞机跑道水泥混凝土道面的基础弹性模量进行反算。通过静载下的实测弯沉、弹性半空间体理论弯沉以及Winkler地基理论弯沉的对比分析;并利用该反算结果,采用PCN来评价道面承载能力。通过某公路飞机跑道的实例,证明该方法较为方便,且精度较好,可以采用。     

飞机滑行荷载对机场道面的随机振动效应分析#$NL 魏保立1,2郭成超2崔璨2

为了保障机场跑道的安全和使用性能,掌握飞机荷载作用于机场道面的机理和机场跑道的损伤失效模式。将机场道面结构视为弹性层状地基上的半无限板,采用振动理论,建立飞机-道面结构的耦合振动分析模型,对飞机滑行荷载所产生的振动作用力进行了计算,并对道面-基础结构在飞机滑行荷载作用下的工况进行了随机振动响应分析。分析结果表明飞机滑行振动荷载中高频作用力更容易引起道面结构的振动,随着频率的增大,振动能量也在不断增加,道面板弯沉值显示出高频振动为主的特性;并且道面结构在飞机-道面耦合作用荷载下产生的弯拉应力在低频附近出现峰值,随着频率的增大,其弯拉应力不再增加,道面结构的弯拉应力主要反映出低频振动特性,道面板弯拉应力出现极限值时,道面板部分出现开裂,开裂部分退出工作状态,其弯拉应力对于高频振动力的响应也随之减小。     

飞机滑行荷载对机场道面的随机振动效应分析

为了保障机场跑道的安全和使用性能,掌握飞机荷载作用于机场道面的机理和机场跑道的损伤失效模式。将机场道面结构视为弹性层状地基上的半无限板,采用振动理论,建立飞机-道面结构的耦合振动分析模型,对飞机滑行荷载所产生的振动作用力进行了计算,并对道面-基础结构在飞机滑行荷载作用下的工况进行了随机振动响应分析。分析结果表明飞机滑行振动荷载中高频作用力更容易引起道面结构的振动,随着频率的增大,振动能量也在不断增加,道面板弯沉值显示出高频振动为主的特性;并且道面结构在飞机-道面耦合作用荷载下产生的弯拉应力在低频附近出现峰值,随着频率的增大,其弯拉应力不再增加,道面结构的弯拉应力主要反映出低频振动特性,道面板弯拉应力出现极限值时,道面板部分出现开裂,开裂部分退出工作状态,其弯拉应力对于高频振动力的响应也随之减小。     

冲击荷载作用下机场刚性道面动力响应与影响因素分析

机场刚性道面受飞机着陆冲击荷载的影响较大。为研究机场刚性道面在飞机着陆瞬态冲击荷载作用下的动力响应,基于主起落架单自由度振动系统,用半波正弦曲线模拟冲击荷载,采用有限元分析的方法研究了B737-800机型在粗暴着陆条件下机场道面的动力响应,并分析了道面板在不同冲击速度及不同道面结构参数下动力响应变化规律。结果表明:单自由度振动系统能很好的表征垂直速度与法向加速度的关系;道面板产生最大应力的临界荷位处于板纵缝中部;冲击荷载作用时间内道面弯沉影响深度持续增加,绝大部分由土基承担;循环冲击作用下,板底弯沉随冲击荷载作用次数的增加而增加,作用100次后增幅明显减小;板底弯沉与板底峰值应力均随垂直速度的增加而增加,相比面层模量,面层厚度对板底弯沉的影响显著,板底峰值应力随面层模量的增大而增大,但随面层厚度的增加呈先减小后增大趋势。     

水泥混凝土路面荷载应力计算理论的试验验证

荷载试验结果表明,板中和板边受荷时弹性半无限地基板的有限元解(位移法),同实测的挠度曲线和应变曲线相吻合,而板角受荷时则Winkler地基板的有限元解符合实测挠度曲线和应变曲线。水泥混凝土路面下地基回弹模量的取值,在板中受荷时要比承载板实测结果提高2～3倍。     

飞机水平荷载作用下水泥混凝土道面结构响应

针对飞机在起飞状态和着陆滑跑时对水泥混凝土道面结构产生较大的水平荷载,采用ANSYS软件建立足尺9块道面板三维有限元分析模型,研究了2种典型飞机起飞时轮载作用于6种荷载位置时道面结构的力学响应,并分析了着陆时水平力系数对道面结构响应的影响.结果表明:起飞时,2种机型对道面结构的应力峰值分别变化了0.12MPa和0.05 MPa;道面板应力峰值与水平荷载呈线性变化,仅在单轮主起落架作用在荷位1时呈非线性关系;轮载作用于板中和纵缝板边时,水平荷载对道面板应力影响较小;轮载作用于板角和横缝中部时,道面板应力峰值同水平荷载方向有关.     

路面板脱空弯沉差判定与自补偿压浆材料处治

针对目前基于弯沉的路面板底脱空判定方法研究的不足及常用压浆材料处治板底脱空存在“二次脱空”的情况,以烟台一威海高速路试验段为依托工程,通过对试验段路面板同板板中心、板边中点和板角弯沉检测数据的统计分析,结合钻孔实测,提出路面板底脱空同板弯沉差判定标准,并引入自膨胀补偿收缩理论改良压浆材料,推荐分别适用于处治路面板底轻度、中度和重度脱空的有机类、水泥类和掺砂类自补偿压浆材料.试验段钻孔复核与弯沉检测结果表明,路面板底脱空同板弯沉差判定标准具有较高的准确度和可信度,推荐的自补偿压浆材料处治效果良好.     

飞机起降荷载作用下的场道地基沉降

基于上海浦东国际机场第一跑道6年多的沉降观测数据,研究了飞机起降荷载作用下的机场跑道沉降规律.根据跑道竣工后尚未开放交通期间的沉降数据,采用对数曲线法得到跑道在恒载条件下的沉降模型,将跑道运营期内推算恒载沉降与实测沉降的差值视为飞机起降荷载作用下的场道地基沉降.分析结果表明,在该跑道通航第5年,飞机起降荷载引起的沉降约占工后总沉降的31%,且这一比例随时间继续增大,说明现有场道地基处理设计方法对飞机起降荷载考虑不足,建议将交通荷载水平作为场道地基处理的设计参数之一.     

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.     

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.     

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.     

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.     

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。     

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.     

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.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that