基于漏磁的表面裂纹识别及评估

通过建立工件表面两条相互平行槽形裂纹的磁偶极子模型，研究了裂纹漏磁信号之间的相互作用关系，根据漏磁信号的峰值特性对裂纹的几何参数进行了定量评估，通过漏磁信号振幅随两裂纹的深度比和裂纹间距的关系计算了其中较小裂纹的深度，实际检测结果表明，综合利用两个邻接裂纹的漏磁信号进行评估的矢量轨迹法对相邻裂纹的定量评估具有较好的可视效果，该方法简单易行，能够快速准确地对裂纹进行估计。     

金属微裂纹的谐振式涡流检测

本文用涡流谐振检测法对金属表面微裂纹的扩展进行测量.裂纹开裂面积对涡流有阻碍和切断作用,造成涡流检测线圈阻抗的相应变化,引起谐振电路品质因数升高、信号检测斜率增大.因此微小的表面裂纹和缺陷即可获得较大的信号电压输出.实际裂纹检测表明,这种方法灵敏度高、探测范围大,容易实现自动检测.     

铸铁件的漏磁检测方法

为了检测轿车变速箱端盖的表面裂纹缺陷 ,提高轿车使用过程中的安全性 ,讨论了采用漏磁检测方法检测轿车变速箱端盖表面缺陷的基本原则 ,采用有限元计算和磁路理论计算相结合的方法 ,解决了铸铁件检测中较难解决的磁化问题。针对检测过程中存在的噪声和检测信号的处理问题 ,提出了针对轿车变速箱端盖漏磁检测信号特征的程序滤波方法 ,实验证明所采用的方案能够很好地满足变速箱端盖表面缺陷的检测需求     

基于改进BP神经网络的微裂纹漏磁定量识别

漏磁检测是铁磁材料常用的无损检测方法之一,定量识别是指通过检测到的漏磁信号识别裂纹的尺寸.采用主成分分析和优化神经网络相结合的建模方法,建立了微裂纹宽度与深度的预测模型.主成分分析去除了数据相关性,减小了输入样本维数,显著简化了网络结构;遗传算法优化的BP神经网络(GA-BP神经网络)可以有效地防止搜索过程中陷入局部最优解.通过基于磁偶极子模型的理论计算与人工刻槽微裂纹漏磁检测实验两种途径验证了该算法在微裂纹定量识别中的应用,为裂纹发展阶段的早期定量识别技术奠定了一定的基础.     

铝质陶瓷在热应力下裂纹形成及扩展的声发射表征

本文将声发射技术应用于陶瓷材料研究领域，通过由传感器，前置放大器，滤波器，主放大器，信号形成器，时基计数器组成的声发射检测系统，精确地测定了陶瓷材料在热应力作用下裂纹生长，扩展的动态过程；发现陶瓷材料在冷却过程中声发射计数率的峰值约为加热过程的４００倍，陶瓷材料在热应力下微裂纹的形成，生长主要发生在冷却过程中；当晶粒尺寸减小时，材料的微裂纹扩展，蔓延逐渐被抑制在较小的范围内。     

水对泥岩损伤作用机理的核磁共振试验研究

为研究泥岩遇水软化的力学特性,对泥岩进行了单轴压缩和核磁共振试验。研究结果表明:(1)水对泥岩的损伤弱化过程如下。浸泡初期,泥岩内部的较小尺度的微裂纹(T_2谱第一峰值)逐渐扩展;较大尺寸的微裂纹(T_2谱第二峰值)显著增加、扩大。随着浸泡时间的增加,相对于较大尺寸(T_2谱第二峰值)的微裂纹,以较小尺寸的微裂纹(T_2谱第一峰值)的迅速扩展、汇聚乃至贯通为主;浸泡至足够长时间时,裂纹贯通形成新的更大尺寸的裂纹,此时,T_2谱分布图上出现第三峰值。(2)水对泥岩的损伤弱化作用主要表现为随着浸泡时间的增加,试件内部的原生微裂纹的进一步扩大和新生裂纹的萌生,二者逐渐汇聚、贯通,从而为水提供更多的通道,使水对泥岩的损伤进一步增强。(3)水对泥岩的强度参数损伤作用极为显著。随着浸泡时间的增加泥岩的单轴抗压强度和弹性模量均随着浸水时间的增加而呈指数形式减小。     

基于GA-BP神经网络的微裂纹漏磁定量识别技术

针对漏磁检测定量识别技术中识别的缺陷尺寸大多为1~10 mm的较大裂纹,与实际自然裂纹相差太大的问题,将基于遗传算法优化的BP神经网络（GA-BP）算法应用到微裂纹缺陷的漏磁定量识别中,使得漏磁检测定量识别缺陷的宽度、深度达到小于0.50 mm的微细裂纹,并通过基于磁偶极子模型的理论计算与漏磁检测实验两种方法构建了微裂纹（0.10~0.30 mm）缺陷样本库.由于在实际检测过程中存在干扰噪声的原因,实验数据的预测结果误差比理论计算数据预测结果明显偏大,最大为16.73%,但预测结果能够基本反映微裂纹缺陷的尺寸大小.      

基于数值试验的混凝土单轴压缩裂纹分布多重分形特征

基于ABAQUS软件,利用多重分形理论对混凝土单轴压缩数值试验表面裂纹分布多重分形谱进行了定量计算.探讨了粗骨料粒径、数值试样尺寸对混凝土表面裂纹分布多重分形谱的影响.建立了基于混凝土数值试样表面裂纹分布多重分形谱峰值的混凝土弹性分形损伤本构方程.结果表明,混凝土在单轴压缩数值试验条件下表面裂纹分布具有多重分形特征,满足自相似性;混凝土数值试样表面裂纹分布多重分形谱峰值介于1.9～2.0,随粗骨料粒径、模型尺寸的增加呈降低的趋势;基于混凝土数值试样表面裂纹分布多重分形谱峰值的混凝土弹性分形损伤本构方程拟合曲线与数值试验应力-应变试验曲线吻合良好.     

基于白光干涉原理的微齿轮几何特征检测

将垂直扫描白光干涉(VSI)测量方法应用于微齿轮的几何特性检测中,该方法具有非接触、大量程、高精度、高效率等特点,水平分辨力为亚微米级,垂直分辨力可以达到纳米量级,并通过Hilbert变换法提取包络峰值来恢复被测表面的三维形貌尺寸。研究结果表明,垂直扫描白光干涉测量方法能够实现微齿轮几何特性的检测,满足设计中提出的精度要求。     

三维埋藏裂纹的非线性Lamb波敏感性研究

采用数值模拟的方法,建立三维埋藏损伤裂纹单元,对非线性Lamb波的敏感性进行研究.利用ABAQUS软件,通过拉伸的方式建立损伤裂纹单元并将其嵌入长板模块中,形成一种肉眼不可见的埋藏裂纹模型,通过侧面激发出单S0模态信号与板中埋藏裂纹的相互作用而产生非线性效应.在相同激励条件下改变裂纹的尺寸从而获得不同的时域接收信号,然后对接收信号进行频谱分析,并对谐波与基波信号幅值比的变化展开研究.频谱图的数值结果表明,非线性Lamb波信号对三维模型中不同尺寸的裂纹具有不同的反应灵敏度,非线性信号会随着裂纹长度或高度的增加而增强,会随着裂纹厚度的增加而变弱,即非线性Lamb波对薄的微裂纹具有更高的敏感性;幅值比的分析表明,该参数可以作为Lamb波早期微裂纹检测的重要指标.     

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.     

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.     

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.