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Koch曲线与分维测量 被引量:3
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作者 李启楷 张跃 +3 位作者 李继忠 刘兵海 李玉清 赵咏秋 《北京科技大学学报》 EI CAS CSCD 北大核心 2000年第4期354-357,共4页
通过构造Koch曲线岛对剖面小岛法测得的分维的准确性和可靠性进行了研究,并研究了Koch曲线岛的初始边长、形状和嵌套层次等构造因素对分维测量的影响.结果表明,剖面小岛法不适合于作为纳米度域的分维测量方法.
关键词 分形 KOCH曲线 分维测量 断裂 断口 金属材料
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疲劳断口分维测量原理及其物理机制 被引量:1
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作者 董聪 郦正能 《北京航空航天大学学报》 EI CAS CSCD 北大核心 1995年第2期28-32,共5页
提出了协同标度因子的概念,研究并指出了目前国际上广泛采用的两种疲劳断口分维测量方法(SIA和FPM)存在的一些实质性问题,认为正确表征断口特性的物理量应是断口的面分维和断口的分形阶数,而不是目前广泛采用的线分维.
关键词 疲劳断裂 断口检查 分维测量 协同标度因子
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一维分形曲线与分维测量
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作者 李启楷 张跃 《冶钢科技》 1998年第1期13-19,共7页
本文对Weierstrass-Mandelbrot和分维布朗理论分形曲线进行了研究,在计算机上进行了模拟计算,并就各种分维测量方法如功率谱分析法、变码尺求教 盒子计数法等进行了评价。结果表明,盒子计数法和功率谱方法的... 本文对Weierstrass-Mandelbrot和分维布朗理论分形曲线进行了研究,在计算机上进行了模拟计算,并就各种分维测量方法如功率谱分析法、变码尺求教 盒子计数法等进行了评价。结果表明,盒子计数法和功率谱方法的测量结果与理论值在的偏差,variation方法虽然能获得较好的测量结果,但可变因素多,为了能获得广泛的应用,仍需进一步作一些工作,为了改善变码尺法的测量精度。 展开更多
关键词 分维测量 一维分形曲线 盒子计数法 功率谱
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二维半岛紊动尾流的分维量测与分析 被引量:1
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作者 李玉梁 田晓东 梁东方 《水力发电学报》 EI CSCD 北大核心 2004年第4期60-64,共5页
应用平面激光诱导荧光 (PLIF)技术观测了水槽中半圆柱形及正弦形半岛后紊动尾流的瞬时浓度分布。对浓度等值线图形进行的分维测量表明紊动尾流具有分形特性 ,且在同一形状半岛后尾流各时刻的分维数不随尾流的周期性摆动而变。同时还研... 应用平面激光诱导荧光 (PLIF)技术观测了水槽中半圆柱形及正弦形半岛后紊动尾流的瞬时浓度分布。对浓度等值线图形进行的分维测量表明紊动尾流具有分形特性 ,且在同一形状半岛后尾流各时刻的分维数不随尾流的周期性摆动而变。同时还研究了分维数与不同的浓度等值线、雷诺数和半岛形状的关系。 展开更多
关键词 水力学 二维半岛 分维测量 平面激光诱发荧光
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PIM粉末颗粒的分形特征及其分形维数 被引量:10
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作者 郑洲顺 曲选辉 《中国机械工程》 EI CAS CSCD 北大核心 2003年第5期436-439,共4页
分析了粉末注射成形几种常用粉末颗粒形状、投影边界、表面的分形特征。介绍了一种适用于粉末颗粒的分维测量方法。根据扫描电镜图片 ,用“数盒子”法测算了羰基铁和羰基镍粉投影边界图形的分形维数 ,它们分别在 1 .0 68~ 1 .0 80、1 .... 分析了粉末注射成形几种常用粉末颗粒形状、投影边界、表面的分形特征。介绍了一种适用于粉末颗粒的分维测量方法。根据扫描电镜图片 ,用“数盒子”法测算了羰基铁和羰基镍粉投影边界图形的分形维数 ,它们分别在 1 .0 68~ 1 .0 80、1 .2 2 5~ 1 .2 3 5之间 ,说明羰基镍粉末颗粒的形状特征有可能用 Koch曲线分形性质来进行描述和分析。分形理论的引入可为研究粉末注射成形提供更准确的定量描述原料特征的方法 ,为粉末注射成形过程的控制提供了更精确的工艺参数。 展开更多
关键词 粉末注射成形 粉末颗粒 分形 分维测量方法
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光散射
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《中国光学》 EI CAS 1998年第2期41-42,共2页
O437 98020974明胶、直链淀粉水溶液胶凝过程的分维测量=Fractaldimension measurement in gelaton processes ofaqueous solution of gelation and amylose[刊,中]/张渭滨,庄荣伟,庄其仁(华侨大学应用物理系.
关键词 光散射 直链淀粉 分维测量 喇曼散射 散射效应 喇曼光谱 应用物理 明胶 华侨大学 水溶液
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TC11钛合金焊接疲劳损伤分行演化方程建立
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作者 邬华芝 郭海丁 +1 位作者 高德平 许开旺 《焊接学报》 EI CAS CSCD 北大核心 2005年第12期93-95,107,共4页
用航空发动机压气机叶盘常用材料TC11钛合金焊接试件,做了控制应变的疲劳寿命试验,获得了最大加载应变与疲劳寿命的关系曲线。应用数据处理技术研究了疲劳断口分维数测量中电镜放大倍数及测量码尺的选择问题,改进了二次电子线扫描分维... 用航空发动机压气机叶盘常用材料TC11钛合金焊接试件,做了控制应变的疲劳寿命试验,获得了最大加载应变与疲劳寿命的关系曲线。应用数据处理技术研究了疲劳断口分维数测量中电镜放大倍数及测量码尺的选择问题,改进了二次电子线扫描分维数处理方法,并成功地应用于钛合金焊接接头断口分维数的测量,获得断口分维数与疲劳寿命关系近似正比例关系。由已建立的焊接结构疲劳损伤分形演化理论模型,建立了一定载荷下TC11钛合金焊接接头疲劳损伤分形演化方程。对航空发动机整体焊接叶盘疲劳寿命预测有重要意义。 展开更多
关键词 焊接连接 疲劳损伤试验 分形演化方程 分维测量
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Rapid Measurement of Short Fiber Content on Hertel Sample
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作者 何晓峰 刘文耀 徐守东 《Journal of Donghua University(English Edition)》 EI CAS 2006年第1期125-129,共5页
This paper offers a new method of measuring short fiber content of cotton fibers. The method is composed of two parts: one is Hertel sampling and the other is image testing. With the help of fiber mixer, a thin and ev... This paper offers a new method of measuring short fiber content of cotton fibers. The method is composed of two parts: one is Hertel sampling and the other is image testing. With the help of fiber mixer, a thin and even cotton net is obtained on which we can get Hertel sample by using a sliver clamp. The near micro optical mechanism consists of one large area CCD and one lens with long focus. This mechanism is able to measure every cotton fiber of the test beard accurately and makes it possible to measure accumulating fibers’ amounts. On this base we can calculate short fiber content of cotton, and the experiment results show that this method is efficient. 展开更多
关键词 cotton fiber short fiber content Hertel sampling image measurement fibrogram
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Development of 2D Temperature and Concentration Measurement Method Using Tunable Diode Laser Absorption Spectroscopy 被引量:7
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作者 Yoshihiro Deguchi Daisuke Yasui Akira Adachi 《Journal of Mechanics Engineering and Automation》 2012年第9期543-549,共7页
Exhaust gas temperature is an important factor in NOx, THC and PM emissions of engines. Especially 2D temperature and concentration distribution plays an important role for the engine efficiency. A thermocouple is int... Exhaust gas temperature is an important factor in NOx, THC and PM emissions of engines. Especially 2D temperature and concentration distribution plays an important role for the engine efficiency. A thermocouple is intrinsically a point temperature measurement method and noncontact 2D temperature distribution cannot be attained by thermocouples. Recently, as a measurement technique with high sensitivity and high response, laser diagnostics has been developed and applied to the actual engine combustions. With these engineering developments, transient phenomena such as start-ups and load changes in engines have been gradually elucidated in various conditions. In this study, the theoretical and experimental research has been conducted in order to develop the noncontact and fast response 2D temperature and concentration distribution measurement method. The method is based on a Computed Tomography (CT) method using absorption spectra of water vapor at 1388 nm. It has been demonstrated that the method has been successfully applied to engine exhausts to measure 2D temperature distributions. 展开更多
关键词 2D temperature measurement tunable diode laser absorption spectroscopy CT (computed tomography) engine exhausts.
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Application of Wavelet Transform in Dual-differential Optical Fiber F-P Interferometric Micro-displacement Measurement System
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作者 ZHANG Shu-qing YANG Feng-lu WANG Xue-qiang BAI Qin-yuan ZHANG Li-guo 《Semiconductor Photonics and Technology》 CAS 2005年第4期263-265,共3页
Based on dual-differential comparing principle, an experimental system of optical fiber F-P interferometric micro-displacement measurement is introduced. It is capable of achieving the absolute displacement measuremen... Based on dual-differential comparing principle, an experimental system of optical fiber F-P interferometric micro-displacement measurement is introduced. It is capable of achieving the absolute displacement measurement, and wavelet transforms is adopted as theory fundament to extract the optical F-P interferometric characteristic signal and remove the noise, so its resolution can reach 0. 01 μm in the dynamic range of 0~ 1 mm. 展开更多
关键词 Optical fiber Fabry-Perot interferometer MICRO-DISPLACEMENT Dual differential Wavelet transform
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A Novel 360°3D Profilometry
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作者 SONG Yuanhe,ZHAO Hong,FAN Hua,CHEN Wenyi,TAN Yushan (Research Institute for Laser & Infrared Applications, Xi’an Jiaotong University,Xi’an 710049,CHN) 《Semiconductor Photonics and Technology》 CAS 1998年第1期45-49,共5页
A new method of 360° turning 3D shape measurement in which light sectioning and phase shifting techniques are both used is presented in this paper.A sine light field is applied in the projected light stripe,meanw... A new method of 360° turning 3D shape measurement in which light sectioning and phase shifting techniques are both used is presented in this paper.A sine light field is applied in the projected light stripe,meanwhile phase shifting technique is used to calculate phase of the light slit.Thereafter wrapped phase distribution of the slit is formed and the unwrapping process will be made by means of the height information based on the light sectioning method.Therefore phase measuring results with better precision can be obtained.At last the target 3D shape data can be produced according to geometric relationships between phases and the object heights.The principles of this method are discussed in detail and experimental results are shown in this paper. 展开更多
关键词 Light Sectioning Phase Shifting Phase Unwrapping Algorithm 3D Shape Measurement
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Food Additives-Ascorbic Acid Quality Assay Test Intelligent Management 被引量:1
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作者 Hairui Zhang Li Zhang +1 位作者 Helin Ye Guofu Zhang 《Journal of Chemistry and Chemical Engineering》 2018年第1期20-25,共6页
In this paper, based on the analysis and test methods of national standards (GB 14754-2010) and chemical analysis and test items carried out by chemical enterprises, a set of automatic processing of quality analysis... In this paper, based on the analysis and test methods of national standards (GB 14754-2010) and chemical analysis and test items carried out by chemical enterprises, a set of automatic processing of quality analysis test data of ascorbic acid products was developed by using access database technology and Visual Basic programming language system, and its stability was investigated. The results show that the software can manage intelligently all aspects of the quality analysis and test of ascorbic acid products, uploading timely the data and results of the analysis and inspection to the network and saving it for users, enterprises and quality management, which set up a network of information sharing platform to ensure the authenticity and reliability of measurement results, improving greatly the speed of data processing, saving valuable time, reducing production costs with good economic efficiency and social benefit. It has practical value for ascorbic acid quality analysis test data processing automatically the results of the implementation of intelligent management. 展开更多
关键词 Food additive ascorbic acid quality analysis test intelligent management software development.
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Assimilating Amounts of Precipitation Using a New Four-Dimensional Variational Method 被引量:3
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作者 LIU Juan-Juan WANG Bin 《Atmospheric and Oceanic Science Letters》 2009年第6期357-361,共5页
Observations of accumulated precipitation are extremely valuable for effectively improving rainfall analysis and forecast. It is, however, difficult to use such observations directly through sequential assimilation me... Observations of accumulated precipitation are extremely valuable for effectively improving rainfall analysis and forecast. It is, however, difficult to use such observations directly through sequential assimilation methods, such as three-dimensional variational data assimilation or an Ensemble Kalman Filter. In this study, the authors illustrate a new approach that makes effective use of precipitation data to improve rainfall forecast. The new method directly obtains an optimal solution in a reduced space by fitting observations with historical time series generated by the model; it also avoids the implementation of tangent linear model and its adjoint. A lot of historical samples are produced as the ensemble of precipitation observations with the fully nonlinear forecast model. The results show that the new approach is capable of extracting information from precipitation observations to improve the analysis and forecast. This method provides comparable performance with the standard fourdimensional variational data assimilation at a much lower computational cost. 展开更多
关键词 4-DVar data assimilation numerical simulation PRECIPITATION
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Latitudinal and climatic distributions of 3D craniofacial features among Holocene populations 被引量:1
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作者 PAN Lei WEI Dong WU XiuJie1? 《Science China Earth Sciences》 SCIE EI CAS 2014年第7期1692-1700,共9页
The geographical and climatic patterning in craniofacial morphology among recent hominids has been regarded as relatively reliable evidence of environmental adaptation and natural selection,which is largely attributed... The geographical and climatic patterning in craniofacial morphology among recent hominids has been regarded as relatively reliable evidence of environmental adaptation and natural selection,which is largely attributed to thermoregulation.However,the relative influence of genetic and environmental factors on craniofacial features is unclear.Our study employed 3D laser scanning techniques to evaluate the association between geographical(latitude),climatic(annual temperature)factors,and 3D craniofacial measurements in 18 recent populations through bivariate correlation analysis.Significant correlations were found among braincase surface area,zygomatic bone surface area,cranial-facial index(facial surface area relative to braincase surface area)and local temperature,and a clear latitudinal gradient was also found in variation of braincase surface area.No significant correlations were found between zygomatic bone surface area,cranial-facial index and latitude.Our analysis supports the idea that the braincase functions as a radiator and is closely related to direct sunlight.We also suggest that absolute/relative craniofacial surface area varies consistently with predictions derived from Bergmann’s Rule.The mosaic craniofacial traits of American Indians may reflect retention of cold-derived,ancestral features,as well as a response to a slightly warmer climate.Because different craniofacial regions preserve environmental/genetic signatures differentially,caution is suggested when craniofacial anatomy is used for phylogenetic reconstruction and functional-morphological analysis. 展开更多
关键词 Holocene population craniofacial morphology surface area LATITUDE temperature
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THE CAPACITY DENSITY AND THE HAUSDORFF DIMENSION OF FRACTAL SETS
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作者 Xu You (Institute of Mathematics, Fudan University, Shanghai 200433, Shanghai, China). 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 1995年第1期43-50,共8页
This paper defines the upper capacity densities of the subsets of R ̄n, gets uniform lower bound of the upper capacity densities for -almost all points of the Hausdorff s-sets or the analytic sets with Hausdorff dimen... This paper defines the upper capacity densities of the subsets of R ̄n, gets uniform lower bound of the upper capacity densities for -almost all points of the Hausdorff s-sets or the analytic sets with Hausdorff dimension s in R ̄n which improves the results of Wen Zhiying and Zhang Yiping's paper in [1]. 展开更多
关键词 Capacity density Hausdorff dimension Fractal set.
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