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排序方式: 共有3098条查询结果,搜索用时 31 毫秒
1.
针对目前金属疲劳裂纹扩展检测方法存在效率低、操作繁琐、精度不高,不能实现实时性等缺点,文章提出了基
于机器视觉的裂纹检测方法。根据金属疲劳裂纹扩展试验过程中裂纹图像的采集要求,设计了摄像头位置可自动调整
的疲劳裂纹图像采集系统,包括摄像头安装运动装置,裂纹图像采集装置以及摄像头运动控制系统。图像采集装置由高
分辨率黑白面阵CCD摄像头、光学镜头,光源照明装置和图像采集卡组成,前3者安装在摄像头支架上,与摄像头运动
装置相连。摄像头运动装置中的X,Y,,Z轴运动机构由步进电机带动滚珠导轨机构。在基于ARM技术的运动控制系统
的控制下摄像头可沿X,Y,,Z轴作高精度直线运动,实现和试件之间精确位置的调整。实验结果表明,所设计的系统可
采集到疲劳裂纹扩展试验过程中高清晰度、高分辨率的试件裂纹图像,满足下一步裂绞尺寸计算的要求;摄像头运动定
位精度可达到0. 02 mm,满足精确的系统聚焦、位置调整、跟踪采集的要求。 相似文献
2.
Open innovation and absorptive capacity are two concepts based on the idea that companies can leverage the knowledge generated externally to improve their innovation performance. The aim of this paper is to analyse the joint effect of open innovation and absorptive capacity on a firm's radical innovation. Open innovation is expressed in terms of external search breadth and depth strategies and absorptive capacity is described by distinguishing between potential and realized absorptive capacity. In order to test our hypotheses, we carried out empirical research in firms operating in high-technology industries. The results indicate that internal routines and processes for absorbing external knowledge help explain radical innovation as they show a significant effect of potential and realized absorptive capacity. Also, there is a moderating effect of absorptive capacity on open innovation. Specifically, potential absorptive capacity exerts a positive effect on the relationship between external search breadth and depth and radical innovation. Realized absorptive capacity moderates the influence of external search breadth. These findings confirm the complementary nature of absorptive capacity and open innovation search strategies on radical innovation. 相似文献
3.
Although increasingly appreciated for their explanatory power in developed societies, marital search models have yet to be widely applied to developing nations. This article evaluates the applicability of marital search models to marriage timing in Mexico. The analysis compares separate models of union formation for men and women that include individual and marriage market predictors. Results show that union formation is closely linked to the uncertainties surrounding the transition to adulthood and the availability of marriageable partners. Improvements in women's economic position do not diminish the attractiveness of marriage, as female independence arguments would suggest. Instead, they are a central force behind the stability of marriage behavior in Mexico. A central transformation identified in the analysis is the reduction in sex differences in age at marriage as women expand their education and labor force participation. 相似文献
4.
Comparison of Four New General Classes of Search Designs 总被引:1,自引:0,他引:1
A factor screening experiment identifies a few important factors from a large list of factors that potentially influence the response. If a list consists of m factors each at three levels, a design is a subset of all possible 3 m runs. This paper considers the problem of finding designs with small numbers of runs, using the search linear model introduced in Srivastava (1975). The paper presents four new general classes of these 'search designs', each with 2 m −1 runs, which permit, at most, two important factors out of m factors to be searched for and identified. The paper compares the designs for 4 ≤ m ≤ 10, using arithmetic and geometric means of the determinants, traces and maximum characteristic roots of particular matrices. Two of the designs are found to be superior in all six criteria studied. The four designs are identical for m = 3 and this design is an optimal design in the class of all search designs under the six criteria. The four designs are also identical for m = 4 under some row and column permutations. 相似文献
5.
分析了采用Delphi6.0编程工具研究并设计的医疗器械商品检索系统,介绍了系统开发的环境特征、数据库应用程序开发步骤及开发过程,包括创建主界面、数据库及编程等,分析了该系统存在的不足及改进措施。 相似文献
6.
在锌表面获得了多种不同颜色且具有金属光泽的不溶性Mo(W)-S-Zn簇合物转化膜,所获膜层具有良好的耐蚀性能和装饰效果,加热处理后颜色将发生变化,加速腐蚀试验结果表明,金黄色膜耐蚀性最佳。FT-IR、FT-Raman、XPS和AES分析表明,该膜层厚度约为60nm。钼在膜表面的价态为+6价,而在膜内则以+6、+4价共存。从AES深度分布曲线可知,其组成为32.5%Zn,19.3%Mo,39.4%S,8.5%O。膜为多分子层组成的复杂体系,其颜色是各组分统计分布的结果。 相似文献
7.
所有权是民法 (外 )物权的核心 ,而所用权则是经济法 (内 )物权的核心。创设所用权具有重大的理论意义和实践意义 ,因为这是在财富创造的竞争中赋予人们一种新的权利并使之得到法制的保障 ,这有利于我们坚持“发展才是硬道理”的原则 ,从而把我国的经济建设搞得更好 相似文献
8.
Sets of relatively short time series arise in many situations. One aspect of their analysis may be the detection of outlying
series. We examine the performance of standard normal outlier tests applied to the means, or to simple functions of the means,
of AR(1) series, not necessarily of equal lengths. Although unequal lengths of series implies that the means have unequal
variances, that are only known approximately, it is shown that nominal significance levels hold good under most circumstances.
Thus a standard outlier test can usefully be applied, avoiding the complication of estimating the time series' parameters.
The test's power is affected by unequal lengths, being higher when the slippage occurs in one of the longer series 相似文献
9.
周晓丽 《东北农业大学学报(社会科学版)》2008,6(1):88-90
黑龙江汉族民歌的衍变历经了数百年的岁月沧桑,它与民族迁徙、人口变迁以及文化传统等存在着极为密切的联系。通过对黑龙江民歌与河北、山东、河南、山西民歌进行比较,表明黑龙江民歌与河北民歌之间存在着较近的亲缘关系。因此,文章试图在对较有代表性的几首黑龙江与河北民歌比较研究的基础上进一步探究黑龙江民歌衍变的影响因素。 相似文献
10.
Dele Olowu 《Habitat International》2003,27(4):501
Of the three most prominent issues in governance discourse—the horizontal coordination of markets, government hierarchies and networks, global governance and multi-level governance—this paper argues that the last, developing and sustaining structures of multi-level governance, constitutes the most profound governance challenge for most developing countries.The paper identifies the major forces promoting change in favor of multi-level governance in developing countries. Using the growing literature and comparative national experiences (illustrated with the examples of India, the Philippines, Colombia and Nigeria), it highlights the key achievements of democratic decentralization as well as its nagging problems in these countries. Finally, the paper demonstrates the significance of these developments for democracy and development in these countries and shows some of the ways by which external partners—especially experts associated with the Geographic Information Systems for Developing Countries can assist and possibly benefit from this process. 相似文献