Damage detection method in complicated beams with varying flexural stiffness

A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method (SSEM), and its applicability condition is introduced. For a beam with the continuously varying flexural stiffness and an edge crack, the SSEM is used to detect the crack location effectively by numerical modal shapes. As a complicated beam, the glass fiber-reinforced composite model of a wind turbine blade is studied based on an experimental modal analysis. The SSEM is used to calculate the damage index from the measured modal parameters and locate the damage position in the blade model successfully. The results indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures for engineering applications.     

Leberfunktionsuntersuchungen mit dem [15N]Ammoniumtest

In laboratory tests a method was developed for a non-contacting moisture gauging on conveyor belts of different materials like coal, clay, industrial slay and stones of inflating clay. The moisture was measured with an ²⁴¹ Am-Be-neutron source, the absolute necessary determination of the changing flow of material was made with the gamma rays of ¹³⁷Cs or ²⁴¹Am. The analysis of the records shows, that to all measuring values mathematical defined curves could be found, so that methods of calculation for the moisture content could be deduced. The maximal obtainable accuracy is about ±0.5 percentage by weight. With the industrial slay and the stones of inflating clay supplementary tests were made direct on the conveyor bell. They shows, that also in the practice good results can be obtained.     

Automatized One-dimensional X-Ray-Detector

One-dimensional gas-filled X-ray detectors with delay line readout have been developed and tested on line with IBM-PC. The pressure of a xenon (90) and CH₄ (10) mixture can be set over a range of 1–10 atm. The position resolution for 8 keV photons is about 170 μm. Main properties and possible applications of the detector are presented.     

Neuere Ergebnisse in der metallurgischen Analyse durch Aktivierung mit 14-MeV-Neutronen

Der Vortrag informiert über neuere Untersuchungen zur Bestimmung des Sauerstoffgehalts verschiedener Metalle, insbesondere des Aluminiums und dessen Legierungen sowie üher die Anwendung programmierbarer Kleinrechner für derartige Analysen durch Aktivierung mit 14-MeV-Neutronen. Als ebenfalls vorteilhaft erwies sich diese Analysentechnik für die Bestimmung von Cer, das als Mikrolegierungsetement für verschiedene Metelle Anwendung findet. Es wird über die Moglichkeiten der Cer-Bestimmung in Metalleu mit unterschiedlichen Cer-Gehalten und im Cer-Mischmetall berichtet.     

Über die Tätigkeit der Ständigen Komission des RGW für die friedliche Anwendung der Atomenenergie auf dem Gebiet der Anwendung von Radionukliden und Kernstrahlungen in der Volkswirtschaft der RGW-Mitgliedsländer

Zur Förderung der Anwendung von Radionukliden und Kernstrahlungen in den verschiedenen Zweigen der Volkswirtschaft der RGW-Mitgliedsländer und zur Organisation eines umfassenden Erfahrungsaustausches im Rahmen des RGW auf diesem Gebiet beschloβ die Ständige Kommission des RGW für die friedliche Anwendung der Atomenergie auf ihrer 3. Tagung im Jahre 1961, eine Zeitweilige Arbeitsgruppe für die Anwendung von Isotopen und Kernstrahlungen zu bilden. Die internationale Leitung dieser Arbeitsgruppe übernahm die VR Polen. Die Delegation der DDR in dieser Arbeitsgruppe wurde von Frau Prof. Dr. L. Herforth, Direktor des Instituts für Anwendung radioaktiver Isotope der TU Dresden, geleitet.     

太赫兹无损检测的研究*

无损检测技术是一种不破坏零件或材料,可直接在现场进行检测的技术,广泛应用于样件的质量评估。太赫兹波具有量子能量低,对大多数非极性物质透明,兼具频谱性和成像性等特点。作为一种新型技术,太赫兹无损检测已经成为现有无损检测技术的有力补充。文章介绍了太赫兹成像系统的工作原理,阐述了基于连续太赫兹成像的无损检测技术在实际样件测试中的应用。实验测试结果表明,一些样件利用太赫兹无损检测技术可测得其内部缺陷。     

铁皮石斛品质影响因素快速无损检测及光谱特性分析

随着人民生活水平的提高,中草药的保健功能越来越得到大家的重视,铁皮石斛是我国名贵中药材,素有“救命仙草”之称。尝试用叶绿素、糖度和pH值作为铁皮石斛的品质指标,选择安徽霍山、浙江雁荡山和云南3个不同产地的铁皮石斛作为研究对象,提取不同铁皮石斛的光谱数据和理化参数,然后进行各品质指标的反演,最终建立品质指标与光谱之间的相关模型,并对模型的有效性进行分析。实验中的研究对象是铁皮石斛的茎,用ASD光谱仪得到三种铁皮石斛茎的光谱数据,再把同一批样本研磨碎,放入离心管中加入甲醇溶液密封,并用锡箔纸包装处理制成相应的溶液,采用分光光度计、糖度计和pH计测量叶绿素含量、糖度和pH值,每个样本分别选取离心试管中的上层,中层,下层溶液检测糖度,测量3次并取平均值,以此结果作为对照组。原始光谱数据通过小波变换去除噪声和降维,将得到的能量系数（包括波段与尺度）,与铁皮石斛对照组的理化参数进行相关性分析,选取决定系数中较高的能量系数作为小波特征,用最小化二乘法对小波特征拟合。用全部实验样本作为测试集,随机选取70%作为验证集,对于浙江雁荡山、安徽霍山和云南三种不同品种铁皮石斛：叶绿素含量反演模型的决定系数（R2）分别为0.819,0.820和0.865,均方根误差（RMSE）分别为为0.035,0.013和0.017;糖度反演模型的决定系数（R2）分别为0.756,0.764和0.823,均方根误差（RMSE）分别为0.025,0.030和0.0368;pH值的反演模型决定系数（R2）分别为0.819,0.820和0.865,均方根误差（RMSE）分别为0.0345,0.013和0.017。从中可以发现,三种不同铁皮石斛的品质反演模型和决定系数（R2）均大于0.80,均方根误差（RMSE）小于0.10。实验证明了铁皮石斛中叶绿素、糖度和pH值的光谱特性对其进行品质评估的可行性。     

Micro-computed tomography based experimental investigation of micro- and macro-mechanical response of particulate composites with void growth

ABSTRACT

In this work, we develop an image-based material testing approach using micro-computed tomography to understand the influence of microstructure and local damage phenomenon on the effective mechanical response of rubber-glass bead composites. Furthermore, a nondestructive, three-dimensional image-based analysis protocol which provides high fidelity of sample testing and data assessment has been established. An investigation was performed on various compositions of silicone rubber reinforced with silica particles. In situ compression experiments were used to study how the microscale damage (void creation from debonding) develops and evolves in the context of four primary studies: (i) effect of particle volume fraction, (ii) effect of particle diameter, (iii) local damage phenomena and its evolution (incremental loading/unloading), and (iv) effect of surface treatments on bonding characteristics. A detailed statistical analysis of the evolution of structural features through robust image processing strategies at various stages of loading was conducted. The rich data analysis collected from the experimental studies offers an understanding of the complex phenomena attributing to the material's macro and microscopic response to loading. Altogether, this framework results in the development of microstructure-statistics-property relations. Furthermore, the mechanical and morphological response of non-linear viscoelastic materials subjected to uniaxial compression is investigated.     

Radiotracer Studies on the Extraction of Metal Ions Part 10: Extraction of Calcium,Iron, Nickel,Copper, and Zinc with Some Aromatic Schiff Bases)

Using the radioactive indicators Ca ⁴⁵, Fe ⁵⁹, Ni ⁶³, Cu ⁶⁴, and Zn ⁶⁵ the yield of extraction (%E) of Ca(II), Fe(III), Ni(II), Cu(II), and Zn(II) with quadridentate Schiff bases, which are products of condensation of salicylaldehyde and its derivatives with ethylenediamine, 1,3-propylenediamine and o-phenylenediamine has been investigated as a function of the pH of the electrolyte.     

Optical and fast nondestructive identification of the ages of leaded ancient pottery

In this paper,based on the one-dimensional(1D) optical superlattice model,we calculate the average reflectivities(ARs) of leaded ancient pottery(AP) made within the last 2000 years,and find that for incident light with a suitable wavelength,the AR of the leaded AP increases monotonously with the increase in the layer number of the silvery glaze(SG) media.Based on this property,we propose an optical nondestructive method for identifying the age of leaded AP by detecting the AR.By using the exhaust algorithm and the discriminant function of variance,we obtain the optimal wavelength range of the incident light to identify the ages of the leaded AP.It is found that in the visible light band,if we choose green light with a wavelength range of 540-540.1 nm as the incident light,leaded AP made within the last 2000 years can be identified swiftly and precisely by detecting the ARs.This will be useful for designing optical instruments for the fast nondestructive identification of the ages of leaded AP.