基于年均小时交通量的卡车荷载预测模型及其对桥梁疲劳损伤影响

车辆实测数据表明,车辆荷载存在明显递增趋势.利用中国安徽省某桥梁长期健康监测数据,定义年平均小时交通量(AAHT)来考虑交通量的周期性和季节性变化,并据此建立季节性差分自回归移动平均模型(SARIMA)模型对未来交通荷载进行预测.同时,基于实测卡车数据的关键参数统计结果,建立多种类型的卡车荷载模型,逐一加载到某T梁桥有限元模型上,研究卡车荷载的非平稳增长对结构疲劳损伤的影响.结果表明,基于AAHT的季节性差分自回归移动平均模型能够准确预测车辆荷载,且车辆的非平稳增长对桥梁疲劳损伤影响显著,考虑车辆荷载非平稳增长时桥梁的疲劳损伤度约为不考虑车辆非平稳增长时的1.7倍.     

灰色马尔柯夫模型在交通量预测中的应用

交通量预测是道路交通规划与路面设计的基础,由于影响交通量生成和增长的因素具有层次复杂性、关系模糊性、动态变化随机性和指标数据不确定性等,从而导致交通量的预测结果与路面实际运营数量之间有较大差异.本文利用改进的灰色GM(1,1)预测模型和马尔柯夫随机过程理论,建立了交通量的灰色马尔柯夫预测模型.实例计算分析表明,该模型具有较强的适用性,预测得到的交通量数据具有较高的精度和可靠度.     

基于交通量调查的大跨PC箱梁跨中区段疲劳应力谱

为分析大跨径预应力混凝土(简称PC)箱梁跨中区段在车辆荷载作用下的疲劳累积损伤,以某PC连续刚构桥为例,对车辆荷载产生的疲劳应力谱进行了研究.首先,运用实桥交通量调查数据,计算得到了等效标准疲劳车的总轴重,据此从相关设计规范中选取了标准疲劳车模型.其次,运用Newmark法进行了动力时程分析,得到了标准疲劳车通过全桥时跨中截面的内力历程,并运用雨流计数法对内力历程进行了计数处理.然后,根据实桥交通量调查数据,分析了桥梁设计基准期内疲劳荷载的循环次数.最后,依据Miner线性累积损伤理论以及桥梁实际受力状况,分别确定了200万次室内疲劳试验的等效疲劳应力幅和疲劳平均应力,由此得到了由车辆荷载产生的疲劳应力谱.     

钢箱混凝土准结合梁焊缝疲劳寿命评估

文章根据广州市内环线恒福路段的交通量调查结果,推导得出了恒福路段高架桥的标准车辆荷载谱,采用MSCPatran软件建立有限元模型,利用标准车辆荷载谱对该桥进行加载,应用MSCNastran、MSCFatigue软件进行有限元分析和疲劳寿命评估二者的整合,对钢箱混凝土准结合梁焊缝进行了疲劳寿命评估,得出合理结论,为该类型桥梁的疲劳问题求解提供了实用计算方法。     

随机车流作用下悬索桥钢桥面板疲劳损伤与寿命评估

为了评估大跨度悬索桥钢桥面板在车流荷载作用下疲劳安全性,在实测车流数据的基础上,采用有限元数值模拟方法对某主跨为820 m的悬索桥钢箱梁顶板-U型肋构造细的疲劳损伤及寿命进行研究。通过对动态称重(WIM)实测车流数据的统计分析建立随机车流模型,基于应力-寿命(S-N)曲线和线性累积损伤准则分析运营状态和交通量增长对悬索桥钢桥面板构造细节疲劳损伤及寿命的影响。研究结果表明:随着密集运行车辆占有率的增加,疲劳损伤呈较缓增长趋势;随着交通量系数的增长,疲劳损伤呈加速增长趋势。与密集运行车辆占有率相比,交通量增长系数对疲劳损伤有较大的影响。在交通量增长系数达到6%时,钢桥面板细节疲劳寿命小于设计基准期,基于实测车流数据的疲劳性能评估对确保钢桥面板在运营期的安全性尤为重要。     

莲城大桥疲劳荷载车辆模型研究

为了确定莲城大桥合适的疲劳荷载车辆频值谱,基于无人机和人工现场实测交通量并且通过对莲城大桥交通量分析,得到了6种车辆荷载频值谱.基于等效损伤原理将得到的6种车型的荷载频值谱转化为3种标准的疲劳荷载车辆模型的频值谱,这3种标准疲劳荷载车辆模型分别为M1、M2和M3,其中M1为2轴车辆模型,总重为135 kN,轴距为3.6...     

基于车辆荷载模型的斜拉索索力随机模拟及疲劳分析

为了满足斜拉索状态评估和养护管理的需求,提出基于车辆荷载模型的斜拉索疲劳寿命分析方法。以桥梁收费站的静态称重数据和桥面监控资料为依据,采用极大似然估计和最大期望(EM)算法,建立了12类车型及车重、轴重、车速等相关参数的车辆荷载统计模型。基于Monte-Carlo方法、泊松过程理论和车辆跟驰模型,编写计算程序进行随机车流仿真分析,随机生成车辆荷载的作用位置和大小,并在影响线上加载得到活载索力时程,将其与长期监测系统得到的实测活载索力时程进行对比分析,验证了该模型的有效性。然后,考虑车辆荷载模型的长期趋势,结合腐蚀斜拉索的应力-疲劳寿命(S-N)曲线和Miner线性累积损伤理论,分别对未腐蚀和腐蚀2种情况的斜拉索长期性能进行了分析与预测。研究结果表明:各车型质量统计数据呈现多峰分布特征,建立随机车辆荷载模型时,宜采用混合分布模型,并考虑车重与轴重之间的相关性;建立的随机车流仿真模型计算得到的活载索力与实测活载索力具有较高的相似度,相对熵(KL)散度在0.1左右,证明该模型能较为准确地模拟实际的交通荷载流,可用于进一步的分析和预测;腐蚀是影响斜拉索疲劳寿命的重要因素,根据试验桥的分析结果,未腐蚀的斜拉索基本不存在疲劳问题,但腐蚀使斜拉索的疲劳寿命迅速降低,甚至会发生早期断裂。     

基于实测的公路桥梁车辆荷载统计模型

基于动态称重系统获取的运营交通基本信息,依据轴组类型对所有车辆进行分类及筛选,建立了6种主要车型的车重、车距、车道交通量、轴重与轴距的统计模型,然后按损伤等效原则提供了6种车型的等效模型车辆,为桥梁疲劳可靠性评估提供了实用的车辆荷载模型.研究表明该建模方法能够准确描述交通荷载,建模过程与方法对同类问题具有普遍意义,可应用于建立各种交通状况下的疲劳车辆荷载模型或提供参考.     

复杂应力耦合作用下斜拉桥正交异性桥面板疲劳断裂

为研究随机车辆荷载与焊接残余应力等复杂应力耦合作用下,斜拉桥主梁正交异性桥面板焊接细节的疲劳断裂性能,以苏通长江大桥为工程背景,在调研统计交通量的基础上,基于Monte-Carlo法建立随机车辆荷载模型,分析随机车辆荷载作用下正交异性桥面板焊接细节的力学行为;基于ANSYS有限元软件,建立焊接细节热分析模型,模拟焊接加热过程与冷却过程,获得焊趾附近残余应力分布。将焊接残余应力作为初始应力,采用数值模拟获得随机车辆荷载与焊接残余应力耦合作用下正交异性桥面板焊接细节的疲劳应力谱。基于双参数疲劳裂纹扩展模型,考虑疲劳裂纹扩展裂纹闭合效应,分析随机车辆荷载与焊接残余应力耦合作用下,正交异性桥面板焊接细节疲劳裂纹扩展行为。结果表明:焊接残余应力与随机车辆荷载耦合作用下,焊接细节疲劳应力幅值远大于车辆荷载作用的应力幅值;在随机车辆荷载与焊接残余应力耦合作用下,正交异性桥面板顶板与U肋焊接节点的剩余疲劳寿命随裂纹长度的增大而下降;焊接残余应力的存在极大地降低了焊接节点的疲劳寿命,与仅考虑随机车辆荷载作用下焊接节点的疲劳寿命相比,焊接残余应力与车辆荷载应力耦合作用下的疲劳寿命下降30%～40%,且疲劳寿命降低幅度随残余应力的增大而增大。     

福州市城市桥梁疲劳荷载研究

通过对福州市城市桥梁交通荷载和运营车辆的装载情况调查,得到由32类日常典型的运营车辆组成的荷载频值谱,以及货运车辆的空载率.根据等效疲劳损伤原理将所得到的荷载频值谱简化为由6辆疲劳荷载模型组成的具有实用性的荷载频值谱.进一步分析得到一辆适宜验算桥面系构件的标准疲劳车辆荷载模型.所得到的疲劳荷载频值谱和疲劳车辆荷载模型,可以供城市钢桥疲劳损伤验算参考.     

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.