基于模态应变能密度理论的网架结构损伤识别方法

为了研究网架结构的损伤检测方法,根据应变能密度理论,提出采用单元模态应变能密度差值作为网架结构损伤识别指标的方法,以损伤单元模态应变能密度差值的大小初步确定单元的损伤程度。分析了5种具有代表性的损伤工况,并在数值计算结果中引入了白噪声。结果显示,在一阶模态下,针对单损伤、多损伤和轻微损伤、严重损伤等不同损伤工况,损伤杆件的模态应变能密度差值均为高值。因此,该方法可以有效识别出网架结构的损伤位置,根据损伤单元的模态应变能密度差值大小初步确定单元的损伤程度,且在一定的噪声水平下具有较强的鲁棒性,对网架结构损伤识别具有参考价值。     

坝体裂缝成因及模态参数识别研究

模态参数识别主要是通过测试得到大坝振动系统参数,包括固有频率、阻尼比、质量、振型等。目前的模态参数识别方法主要有:时域法、频域法、时频结合法、模拟进化法等。研究表明,时域分析法可以提高损伤辨识精度,并可以快速的将损伤定位,对于坝体裂缝识别效果显著。综合国内外结构损伤研究现状,首先对大坝坝体裂缝成因进行探讨,随后介绍了6种常见的模态参数识别方法,并对裂缝后的大坝结构进行模态参数识别。希望对今后坝体裂缝损伤评估提供理论参考。     

某多功能用车带挡风玻璃白车身模态分析

CAE模态分析技术和试验模态分析技术是获得车身结构动态特性的两种重要方法,且目前在汽车领域都得到了广泛应用。识别车身系统模态对避免车身结构与声腔共振、降低车内噪声有着重要的意义。本丈以某多功能用车带挡风玻璃白车身(BIP)为例,利用有限元法和试验法分别建立车身结构模型,进行模态分析计算,从而获得车身结构的模态频率和模态振型,并验证了CAE分析模型的正确性。     

直齿圆柱齿轮振动特性的模态分析

基于直齿圆柱齿轮的动态分析和优化设计的需要,运用ANSYS有限元分析软件建立其三维实体模型,并对该齿轮振动特性的模态进行分析,得到了结构的低阶模态频率和振型分布,对齿轮的动态分析和优化设计提供理论指导。     

基于ANSYS Workbench精密轴系摩擦力矩测量仪水平轴系的模态分析

本文以精密轴系摩擦力矩测量仪水平轴系为研究对象,采用CATIA进行三维实体建模,并将模型导入到ANSYS Workbench中,对水平轴系上的扭矩传感器和用联轴器相连接的扭矩电机进行静力学分析,得到扭矩传感器和扭矩电机的等效应力图和位移图,再分别对其进行模态分析,并获得水平轴扭矩传感器和扭矩电机的前六阶固有频率及振型,通过分析,得出结论,该水平轴系不会发生共振,为今后精密轴系摩擦力矩测量仪的结构优化设计提供了良好的理论依据。     

新型氧传感器及测氧仪研发成功

中科院长春应化所研发成功一种结构新颖、体积小、成本低、稳定性强、使用寿命长、检测范围广、灵敏度高、具有自主知识产权的新型氧传感器及测氧仪，并通过了专家鉴定。专家认为，该新型氧传感器及测氧仪在检测氧度范围和灵敏度方面达到国内领先水平。     

管道内高速传播火焰传感器的研制及应用

研制了管道内高速传播火焰检测用的光电传感器,并应用于溶解乙炔干式回火防止器回火性能测试仪。传感器具有结构简单,灵敏度高,可靠性好等特点。     

机器状态监测与诊断振动状态监测第1部分：总则（摘选）（二）

5．2．6．2轴相对箱体的相对运动GB厂T 11348系列标准对不同类别机器的旋转轴宽带振动位移测量提供了具体方法和仪器。使用两个非接触式传感器可最好地测量相对振动，布置这些传感器测量在同一横向平面上旋转轴或旋转部件与固定部件之间的径向相对运动。图6给出了这样一种非接触式传感器系统的典型设置。     

用电容传感器测量煤粉喷吹系统的固相浓度

介绍了一种用于测量煤粉喷吹系统固相浓度的电容传感器,由于采用了具有补偿特性的高频振荡测量电路,该传感器灵敏度和稳定性大大提高．可以适用于煤粉喷吹系统中固相浓度较低的气固两相流的测量。此外,传感器安装在管道外侧,实现了非接触测量,故对流动无影响,而且测量值与整个管道流通截面上的煤粉总量成正比．提高了测量准确性。实验室测试表明,该传感器能基本满足实际测量的要求。     

基于不确定性推理的多传感器故障检测平台

针对复杂数控加工中心的故障呈现非线性、非平稳性、弱信息等不确定性特点,为向复杂数控加工中心故障诊断系统设计提供分析基础,以复杂立式加工中心为对象建立多传感器分布式故障检测平台。提出基于检测平台的复杂数控加工中心静态精度和机械动态特性相结合的样本获取方法以及故障推理方法,设计由3种局部检测装置(电涡流传感器、声发射传感器、直线度测量传感器)分别组成的并行和串行结构检测融合系统,且各局部检测装置在同一故障模式下都是独立和同分布的进行检测,通过利用主观贝叶斯推理,获取判决规则,最后产生全局判决。实验表明较传统的单一传感器检测分析方法,该平台具有故障信息识别率高、诊断速度快等优点,为复杂数控加工中心多信息融合故障诊断研究提供可靠样本数据。     

基于改进谱聚类算法在图像分割中的应用

为解决谱聚类算法应用于图像分割时,相似矩阵内存占用较大甚至满溢以及后续计算量大的问题,利用Nystrom方法随机获取一部分样本点,根据样本点和样本点、样本点和非样本点2种相似关系近似表征所有像素点的相似性,得到原图像的近似相似矩阵。在构建上述所需2种相似关系的相似矩阵时,距离度量采用余弦函数。结果表明,采用近邻传播聚类算法代替k-means算法对得到的低维向量子空间聚类,克服了聚类过程对初始值的敏感性,得到的分割结果较稳定,4幅真实图片也验证了研究算法的优越性。改进的谱聚类算法为图像分割的稳定性研究提供了依据。     

基于多尺度小波的图像增强算法

提出了一种基于多尺度小波的图像增强算法.首先对图像做小波分层,利用散布矩阵对分层后的图像提取更丰富的局部结构信息,最后对每一个子图像进行局部直方图均衡化,就可将这些子图像合成为一个完整的输出图像.实验结果表明该方法的增强效果明显优于传统的直方图均衡化方法,既提高了图像的整体对比度又突出了图像的局部细节,同时还抑制了噪声...     

An alternative estimate of real inventory change for national economic accounts

In 1996, the Bureau of Economic Analysis adopted the Fisher index (a particular superlative index) for the national income and product accounts of the United States (NIPAs). This change was, on balance, a major improvement in the US national accounts, for it greatly improved the measurement of rates of growth of real economic aggregates. However, the change posed a special problem for inventories: the Fisher index is not suitable for time series that, like inventory change, exhibit changes in sign. The Fisher quantity relative is the geometric mean of Laspeyres and Paasche quantity relatives. When some detailed components of inventory change are negative, the Laspeyres and Paasche can easily differ in sign, in which case the Fisher index is undefined. In the NIPAs, this problem is avoided by measuring real-inventory change as the period-to-period change in inventory stocks. However, attempts to approximate real GDP by two-stage aggregation, combining this measure of inventory change and other major GDP subaggregates, show that the NIPA measures of real inventory change and of real GDP are inconsistent. This paper attempts to resolve the problem by investigating an alternative measure of inventory change.The alternative measure of inventory change considered is the difference between a Fisher index of inventory acquisitions and a Fisher index of inventory disposals. The consistency of this measure with real GDP is first examined analytically. It is shown that, for inventory changes likely to be observed, the approximation error in the aggregation of GDP components due to measuring inventory change as the difference between Fisher indexes of inventory acquisitions and disposals should be small. Second, the consistency of the alternative measure with real GDP is tested over the period 1977–98. The tests compare the actual approximation errors in the two-stage aggregation of GDP using inventory change based on the two methods: the present NIPA methodology and the alternative, Fisher difference method. These tests provide further support for the alternative method of estimating real inventory change.     

基于双机控制的LED大屏幕动态显示系统

介绍了一种由PC机与单片机双机控制的 LED大屏幕显示系统的设计方法。PC机编辑显示内容,由汉字多点阵字模提取子程序生成汉字点阵,以串行方式发送字模信息和控制信息,80C51单片机接收来自上位机的数据并存储于RAM,经转码子程序将显示内容转换为合适的形式输出给LED大屏幕,实现动态循环显示。     

The Information Content of Method of Payment in Mergers: Evidence from Real Estate Investment Trusts (REITs)

We provide evidence on the information content of the method of payment in mergers by examining shareholder returns in a sample of REIT mergers over the period 1994–1998. When the target firm is publicly held, we find that transactions are always stock-financed, and that acquiring firm shareholders sustain small negative returns around the announcement date. When the target is privately held, cash financing, mixed (stock and cash) financing, and placement of blocks of acquirer stock with target owners are more prevalent. Acquirer returns are positive in stock-financed mergers when the target is private, which is consistent with both the information signaling and monitoring by blockholders hypotheses. Further analysis supports the information signaling hypothesis as the dominant explanation. The effects of other explanatory variables are similar whether the target is public or private. Most significantly, acquiring shareholder returns are negatively related to the acquirer's size, but positively related to the acquirer's use of the UPREIT organizational structure. The positive wealth effects of the UPREIT structure are not fully explained as the capitalization of tax benefits.     

A Further Note on Endogenous Spillovers in a Non-tournament R&;D Duopoly

This note considers the paper of Poyago-Theotoky (1999) on strategic R&D with endogenous spillovers. It proves through an example that, under R&D collusion, optimality sometimes requires either minimal or asymmetric spillovers. It also provides a simple sufficient condition for optimal spillovers between colluding firms to involve maximal spillovers (i.e., complete sharing of information).      

基于k-means的纸质心电图数字化信息提取研究

针对临床诊断中纸质心电图容易遭到不同程度的损坏,且不便于保存的问题,探讨了纸质心电图的数字化问题。采用均值法降噪,在Sobel算法中加入了45°和135°2个方向的模板,利用k-means方法进行了改进,从而得到更加精准的心电图的数字化提取图形。实际验证发现,心电图的数字化提取精度得到了有效提升,有望在医疗实际中推广应用。     

How Network Strategies and Institutional Transitions Evolve in Asia

This article contributes to the literature on network strategies and institutional transitions in emerging economies in Asia by identifying a realistic, intermediate phase between the early and late phases of institutional transitions suggested by Peng (2003). Focusing on the intermediate phase, we advance two arguments based on network strength and network content. First, in terms of network strength, we leverage earlier insights that networks can be classified as strong ties and weak ties. Consequently, we suggest that as institutional transitions unfold, strong-tie-based networks, instead of being phased out, are being transformed into weak-ties-based networks. Second, from a network content standpoint, we argue that the various scale and scope of institutional transitions shape the content of different networks which focus on business-to-government (B2G) ties and business-to-business (B2B) relationships. Our propositions delineate how different transitions of political and legal institutions affect the evolution of B2G and B2B networks. Overall, we suggest that networks not only differ in strength but also in content, and that their evolution is driven by the impact of different dimensions of institutional transitions governing B2G and B2B relationships. Mike W. Peng (Ph.D., University of Washington) is a professor of global strategy at the University of Texas at Dallas, where he holds the university's first ever Provost's Distinguished Research Professorship. He was formerly an associate professor at the Fisher College of Business, The Ohio State University. He is the author of nearly 40 scholarly articles and three books, including, most recently, Global Strategy (2006). He has served on the editorial boards of AMJ, AMR, JIBS, and SMJ, and acted as a guest editor for JIBS and JMS. He is the first elected officer of the Global Strategy Interest Group at the Strategic Management Society. This is his fifth contribution to APJM. Jessie Qi Zhou is a Ph.D. candidate in international business at the Fisher College of Business, The Ohio State University. Her research interest includes strategy in emerging economies, network strategy, and organizational learning. Her main theoretical interest is institutional theory, with a focus on how institutional distance affects MNE strategies. The comparative analysis of firms' strategic choices across countries in response to different institutional environments is also of particular interest to her. Her work has been presented at the Academy of Management and Academy of International Business conferences.     

摩托车车架的试验模态分析

利用脉冲激励法对某２５０型摩托车车架进行了试验模态分析,并介绍了试验模态分析的方法和设备;所得模态分析结果可为车架的结构设计及整车的振动分析提供依据。