基于PSO-LSSVM的疲劳裂纹漏磁定量识别技术

针对疲劳裂纹难以定量识别的问题,提出一种将主成分分析（PCA）和粒子群优化的最小二乘支持向量机（PSO-LSSVM）相结合的建模方法,通过建立漏磁信号与疲劳裂纹宽度、深度之间的非线性映射关系,对疲劳裂纹宽度、深度进行定量识别.搭建漏磁检测系统,采用疲劳拉伸试验制备一系列疲劳裂纹样本,通过疲劳裂纹漏磁定量识别实验,建立漏磁缺陷样本库,对基于PSO-LSSVM的疲劳裂纹漏磁定量识别方法的可行性进行验证.结果表明,该方法能够有效定量识别尺寸小于1 mm;疲劳裂纹的宽度、深度,误差在0.1 mm左右.      

海底管线缺陷内检测技术与装备工程化研究技术总结

漏磁检测是在管道内检测中应用最广泛的一种无损检测技术,检测数据量化与分析是气难点。在技术方面针对课题重点研究的关键技术开展了一系列研究,提出了油气管道漏磁检测数据的分类和量化方法,并基于此研发出一套漏磁检测数据分析软件。漏磁检测中缺陷量化困难的原因在于缺陷的形态对漏磁场的形态有复杂的非线性的影响,继而影响对漏磁信号的定量解释,因此,根据缺陷的开口形状将缺陷进行分类,对于实现将其准确量化是十分必要的。再者,由于实际检测条件的限制,往往只能通过空间离散的漏磁感应强度信号的一维分量推算缺陷的三维形态,这本身不适合使用精确的数学或者统计模型加以描述。使用神经网络对缺陷进行量化,是漏磁检测缺陷量化领域近20年来的一个研究热点。根据课题研究内容以及检测器设计指标,提出了一种基于改进径向基函数网络的量化算法,它以缺陷漏磁场信号的特征量为输入,输出向量为缺陷的三维外形参数。径向基函数网络是一种局部最佳逼近网络,但漏磁检测中漏磁感应强度信号与缺陷外形之间强烈的非线性关系,往往更要求所选用的网络能够识别两者间的内在联系,并使得面对新的数据时仍有合理的量化结果。为此,对径向基函数网络做出基于泛化能力优化的改进,提出新的评价函数,并采用能够迅速适应新样本的在线学习算法,实验验证表明,的确能大幅提高网络的泛化能力。在实际工程检测管道中,多缺陷聚集会明显影响漏磁场的形态,轴向槽缺陷漏磁场与两个坑状缺陷信号波形极为相似,缓变缺陷漏磁场信号变化趋势较小,这对定量漏磁检测的实用化是不容忽视的问题。讨论了不同类型缺陷漏磁场形态和强度的影响,并测试了量化神经网络对缺陷间隔变化的适应能力。研究以分类和量化算法为核心,研发一套漏磁检测数据分析系统。该系统配合内检测器已项目中投入测试,对牵拉实验数据分析的结果验证了所提出算法的确具有优秀的量化性能。     

新型脉冲漏磁传感器的仿真设计与实验研究

在对带保温层管道进行检测时,由于保温层的隔离作用使得传统的电磁无损检测方法感生的磁场在传播到管道表面时已衰减的非常微弱,因此,对带保温层管道中腐蚀缺陷的检测是无损检测领域的一个难点.脉冲漏磁方法由于结合了脉冲检测频率丰富以及漏磁检测适于铁磁性管道检测的优势,因而采用脉冲漏磁技术对管道腐蚀缺陷进行了检测.在分析了脉冲漏磁检测原理的基础上,仿真分析了4种不同结构的脉冲漏磁传感器沿管道表面和管壁的磁场分布以及对不同厚度保温层的检测能力,仿真结果表明带聚磁板的模型具有较好的检测能力.最后,采用实验的方法研究了这种模型传感器对腐蚀缺陷深度的定量能力,实验结果表明该传感器可以很好地实现对腐蚀缺陷深度的定量检测.     

基于超声导波的管道缺陷量化评估仿真研究

超声导波是近年新兴的无损检测技术,相比超声检测和漏磁检测等传统方法,它可提供大范围、全面高效的检测,因此受到越来越多的关注。在基于超声导波的管道缺陷检测中,普遍采用脉冲回波方法,即根据反射回波信号的分析结果获取缺陷信息,目前此技术已可实现管道缺陷的识别和定位。但由于实际管道缺陷形态不规则,产生的反射回波信号往往很复杂,目前还不能实现管道缺陷的量化检测。本文针对此问题,通过有限元仿真方法研究超声导波与管道缺陷的交互过程,提出利用缺陷前后边界分别产生的两个反射信号进行缺陷轴向尺寸的量化评估方法,并进一步通过有限元仿真验证了结论。     

ANSYS在管道漏磁检测中的应用

通过对管道漏磁检测技术和有限元分析软件ANSYS的介绍，得到了有限元分析软件ANSYS在管道漏磁检测中应用的具体事例，通过计算分析得出一系列管道缺陷的漏磁信号曲线，为实现管道缺陷的智能诊断打下了基础。     

缺陷参数与漏磁信号相互关系的实验研究

为了评价无缝钢管表面缺陷的严重程度,必须估测出缺陷的深度、宽度等参数。文章阐述了漏磁探伤中缺陷参数和漏磁信号的相互关系。通过对实验结果的分析表明：缺陷的深度、宽度及倾角分别与漏磁信号的幅值成一定的函数关系,根据信号的特征可反演出缺陷的大小。     

缺陷长度对漏磁场的影响

漏磁检测的量化问题是漏磁检测应用推广需要解决的关健问题,对缺陷漏磁场特征与缺陷长度的关系进行了研究,表明缺陷长度是影响漏磁检测缺陷量化的重要参数。     

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.      

小波神经网络在海底石油管道漏磁缺陷检测中的应用

海底管道漏磁检测信号处理的主要任务是根据霍尔传感器检测到的缺陷的漏磁信号识别缺陷的形态参数,噪声消除和缺陷识别是其中的关键问题。利用噪声信号和测试信号在各个尺度上波谱的不同特征,基于小波变换来消除管道漏磁检测中的噪声信号,并根据正交小波多尺度多分辨率特点,把信号分解成各相互独立的频带,构建一个小波神经网络系统,通过输入漏磁信号的特征量识别缺陷的参数。漏磁检测数据处理实验表明该小波变换能较好地去除检测信号中的主要噪声,所建立的缺陷识别小波神经网络系统具有收敛速度快、逼近精度高等特点。     

小波神经网络在海底石油管道漏磁缺陷检测中的应用

海底管道漏磁检测信号处理的主要任务是根据霍尔传感器检测到的缺陷的漏磁信号识别缺陷的形态参数,噪声消除和缺陷识别是其中的关键问题。利用噪声信号和测试信号在各个尺度上波谱的不同特征,基于小波变换来消除管道漏磁检测中的噪声信号,并根据正交小波多尺度多分辨率特点,把信号分解成各相互独立的频带,构建一个小波神经网络系统,通过输入漏磁信号的特征量识别缺陷的参数。漏磁检测数据处理实验表明该小波变换能较好地去除检测信号中的主要噪声,所建立的缺陷识别小波神经网络系统具有收敛速度快、逼近精度高等特点。     

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.     

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.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-