SR电机的定子模态分析

开关磁阻电机(SR电机)定子固有频率研究对降低电机的噪声具有重要意义.给出了SR电机定子振动模态分析的数学模型,利用ANSYS有限元软件对二维和三维模型进行计算和分析.结果表明,利用二维模型代替三维模型对定子进行预估计切实可行,可以大大减少工作量,提高计算速度.     

拖拉机驾驶室的模态声学贡献度分析

为确认影响拖拉机驾驶员耳旁噪声的主要振动模态,建立了拖拉机驾驶室声场中声压值与结构模态及模态声学贡献度数值的计算模型.利用驾驶室声-固耦合有限元模型进行仿真,分析了驾驶员耳旁噪声各频段峰值处的各阶模态贡献度值,并确认了峰值处的主导振动模态;利用主导振动模态来指导驾驶室主要振动模态的整改,且对主要模态整改前后驾驶员耳旁噪声声压级进行了对比.结果表明:驾驶室主要模态的改进可明显降低驾驶员耳旁噪声信号峰值,且峰值所在频段内的声压级也有所降低,可以实现分频段控制噪声,有效降低噪声.     

考虑定子各向异性的永磁同步电机振动噪声优化

为了有效降低永磁同步电机的振动和噪声,在考虑定子各向异性建模的基础上,提出了一种通过定子结构模态规划来优化振动噪声的方法。首先分析了对定子模态频率较为敏感的各向异性材料参数,通过定子铁芯和总成的模态试验进行了参数识别;随后分析了电机在额定工况下的振动和噪声峰值来源,并且在电磁力二维分解的基础上提出了降低电机噪声的模态规划目标;最后分析了主要结构参数对定子模态频率的灵敏度,最终选择定子轭部厚度作为优化参数来实现模态频率的规划。研究结果表明:通过考虑定子材料的各向异性可以建立较为准确的定子模型,模态频率计算值与实测结果的误差都在4%以内;仿真优化后的电机振动峰值下降了58%,总体噪声功率级(A)降低了4.3dB。     

SRV车内声辐射分析

文章建立SRV(运动休闲车)车室声腔的声学模型,计算声腔的声学模态,并与白车身结构模态对比,分析声学模态和结构模态的耦合情况;根据车身频率响应,分析车内噪声声场及车身板件的结构振动对车内声学贡献的影响,车内噪声声场得到实验验证,为降低车内结构噪声提供依据.     

立铣动力学系统模态参数辨识及实验

设计完整的铣削加工模态分析实验和动力学实验,完成铣削力和振动信号的采集和分析,并以刀具振动系统为例提出模态参数辨识计算方法.对比动力学实验测量和计算机仿真信号的时域幅值、功率谱特性可知:基于实验模态分析实现系统模态参数辨识技术路线可行,预测精度较高,可较好地应用于铣削力-振动等信号及其时域和频域特性的动态仿真.     

流固耦合对油底壳振-声特性的影响研究

对于复合钢板油底壳进行了自由模态、约束模态以及流固耦合下湿模态的计算与试验,较高的一致性表明耦合模型是合理的.模态对比结果说明当油底壳盛油后,模态振型出现了变化,且整体模态频率降低.使用最小二乘法拟合了盛油前后油底壳的瑞利阻尼比例系数.结果表明润滑油对于复合钢板油底壳的阻尼影响不大.采用多体动力学计算了耦合与非耦合油底壳的振动响应,在整体幅值和变化趋势上与试验值较接近.耦合模型的振动响应在整体上略低于非耦合模型,但500 Hz前的振动峰值更突出,尤其在330 Hz附近.耦合模型在峰值频率和趋势上与试验值吻合得更好.进一步通过边界元法计算了两种油底壳模型的辐射噪声,结果显示考虑耦合后油底壳辐射声功率在3 000 Hz内显著下降,仅在333 Hz处有较高的峰值.      

基于CEEMD-SVD-LSSVM的矿浆管线核心设备故障诊断

针对单向阀振动信号包含背景噪声、故障特征提取困难和诊断准确率不高的问题,提出互补集合经验模态分解(CEEMD)、奇异值分解(SVD)和最小二乘支持向量机(LSSVM)相结合的故障诊断方法.首先,用CEEMD分解单向阀振动信号,并用能量分析法及互相关分析法来选取有用的本征模态函数(IMF).然后,根据SVD法提取相应的故障特征,并输入LSSVM进行故障诊断.通过与集合经验模态分解(EEMD)、支持向量机(SVM)等的比较,表明该方法不仅消除了模态混叠和信号噪声,而且能有效地提取单向阀的故障特征,得到更高的诊断准确率.     

工程结构模态的连续型随机子空间分解识别方法

环境振动识别方法利用结构的输出信号识别结构的模态参数,主要的识别方法有时间序列分析法、ERA(eigensystem realization algorithm)法和随机子空间法,这些方法均基于离散模型．基于连续随机子空间模型,本文给出了一种识别大型工程结构模态参数的方法．运用SVD(singular value decomposition)分解将含噪声的输出信号空间分解为信号空间和噪声空间,然后直接估计结构的模态参数．SVD分解保证了算法的鲁棒性．最后讨论了一个7层框架的理想建筑,仿真计算表明,该方法简单有效,能够使用在桥梁和建筑的健康监测和振动控制中．     

基于经验模态分解的无量纲指标故障诊断定位

无量纲指标作为新的理论工具应用于故障诊断研究中,虽然取得了一定的进展,但在应用时没有考虑到其他噪声干扰信号的影响,对结果分析有一定的干扰.而经验模态分解(EMD)技术能够提取出振动数据的故障特征信号,针对无量纲指标分析数据时的噪声干扰,提出了基于EMD的无量纲指标处理算法.首先对采集到的振动数据做EMD,分解出的前几个固有模态函数(IMF)分量中包含了振动数据的故障特征,去除其他噪声干扰信号的影响;其次求出含有振动数据特征信号的IMF分量的无量纲指标值,做出其无量纲指标的特征范围值;最后进行故障诊断分析.将此算法应用于旋转机械的故障诊断实验中,通过实验验证了该方法的可行性和有效性.     

齿轮箱振动预测分析及试验验证研究①

本文以某齿轮箱为研究对象,应用MASTA软件根据动力学理论完成对齿轮传动系统的建模,得到轴承处动态力并以此作为之后箱体的输入载荷,综合运用Pro/E、Hypermesh与Ansys软件建立齿轮箱箱体有限元模型,计算齿轮箱模态并调入Virtual Lab软件中基于模态叠加法最终得到固定转速下齿轮箱各点振动响应,经验证,与振动试验测量值相吻合。本文通过多软件联合计算仿真成功求解齿轮箱箱体振动响应,有助于预测整体系统振动噪声,为齿轮箱振动控制提供了理论依据。     

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.     

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.     

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。     

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.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with