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31.
For more than three decades the International Atomic Energy Agency (IAEA) has supported projects on food, nutrition and environment
for strengthening the analytical capabilities in developing countries (DCs). Over time, such efforts have led to the development
of proper study designs, harmonization of sampling protocols, adequate contamination control and evaluation of the suitability
of competing analytical techniques for the determination of specific analytes. Collectively, these consistent IAEA initiatives
have promoted harmonization of chemical measurements thus facilitating comparability of results of filed investigations. Importantly,
the Agency's efforts have infused a measure of metrological awareness in measurements carried out in field studies, including
physiological measurements. Nuclear and isotopic techniques have played an important role in reaching these goals by establishing
reliable measurement processes for application in health care studies. 相似文献
32.
In this paper, we report 30 THz measurements of ammonia in its excited, ν2 = 1, inversion state. These measurements include transition frequencies and pressure shifts (where significant enough to be observed). Included in the data are two forbidden and three ro-inversion transitions, as well as 18 transitions never directly measured before. The measurements were made with an all-solid-state, diode-laser, difference-frequency spectrometer. Using an innovative laser-frequency locking scheme, this spectrometer provided accurately determined and continuously tuned THz-frequencies without requiring accurate knowledge of the absolute laser frequencies. The details of the spectrometer’s frequency calibration is discussed. A global analysis of NH3 based on the available ground state, ν2 = 1 state, and ν2-band transitions was carried out, and the resulting set of recommended molecular effective-Hamiltonian parameters for ammonia is presented. In addition, calculated center frequencies and intensities for all possible transitions up to J = 20 between rotation, inversion, and vibration levels in the ground and ν2 = 1 states are included as supplementary material. 相似文献
33.
Simulation of dynamic speckle sequences and its application to the analysis of transient processes 总被引:2,自引:0,他引:2
A. Federico G.H. Kaufmann G.E. Galizzi H. Rabal M. Trivi R. Arizaga 《Optics Communications》2006,260(2):493-499
Dynamic speckle has been used in recent years to analyse several transient processes that are produced in industrial and biological applications. We present here a numerical simulation to generate a temporal sequence of dynamic speckle patterns which is based on a model used for speckle formation by the superposition of waves from discrete scattering centres. It is demonstrated that the first and second statistics of the intensity of each speckle image, the time history of the speckle pattern, the temporal evolution of the correlation coefficient, and the power spectral density of the intensity generated by the proposed model reproduce quite well those obtained from experimentally recorded data. The process of a fast drying paint is presented as an example of the application of the proposed numerical model. 相似文献
34.
Real-time visualisation of deformation fields using speckle interferometry and temporal phase unwrapping 总被引:1,自引:0,他引:1
A real-time system for analysing data from speckle interferometers, and speckle shearing interferometers, has been developed. Interferograms are continuously recorded by a digital camera at a rate of 60 frames s−1 with temporal phase shifting carried out at the same rate. The images are analysed using a pipeline image processor. With a standard 4-frame phase-shifting algorithm (phase steps of π/2), wrapped phase maps are calculated and displayed at 15 frames s−1. These are unwrapped using a temporal phase unwrapping algorithm to provide a real-time colour-coded display of the relevant displacement component. Each camera pixel (or cluster of pixels) behaves in effect as an independent displacement sensor. The reference speckle interferogram is updated automatically at regular user-defined intervals, allowing arbitrarily large deformations to be measured and errors due to speckle decorrelation to be minimised. The system has been applied to the problem of detecting sub-surface delamination cracks in carbon fibre composite panels. 相似文献
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37.
Anneli Kruve Riin Rebane Karin Kipper Maarja-Liisa Oldekop Hanno Evard Koit Herodes Pekka Ravio Ivo Leito 《Analytica chimica acta》2015
This is the part I of a tutorial review intending to give an overview of the state of the art of method validation in liquid chromatography mass spectrometry (LC–MS) and discuss specific issues that arise with MS (and MS/MS) detection in LC (as opposed to the “conventional” detectors). The Part I briefly introduces the principles of operation of LC–MS (emphasizing the aspects important from the validation point of view, in particular the ionization process and ionization suppression/enhancement); reviews the main validation guideline documents and discusses in detail the following performance parameters: selectivity/specificity/identity, ruggedness/robustness, limit of detection, limit of quantification, decision limit and detection capability. With every method performance characteristic its essence and terminology are addressed, the current status of treating it is reviewed and recommendations are given, how to determine it, specifically in the case of LC–MS methods. 相似文献
38.
通过对散斑计量法原理分析、数学描述及观测实例的论述,证明激光散斑法是研究煤矿地下结构物相似模型变形状态的一种新的无损检测技术,若采用白光作为光源,该项技术可用于二维变形场的实地测试。 相似文献
39.
In speckle photograph technology, to determine the displacement of the points on the surface of the measured body, the conventional
method is to put the film which has recorded the speckle patterns before and after displacement into a system of optical Fourier
transforms. After filtering on the spectrum plane, the experimentalist can obtain the displacement information from the interference
pattern on the image plane. Instead of setting up a complex optical Fourier transform system, we consider the speckle field
as a light intensity function of 2 dimensions, which will change with different positioning of the points. After working on
the function's discrete Fourier transform (DFT), according to one of the properties of Fourier transformation, the displacement
of the measured point is involved in the phase of its spectrum. Having extracted the displacement information from the phase,
we obtain the distribution of the displacement field. In this paper, we deduce the expression for the displacement field by
using Fourier transformation under conditions of both equal and unequal displacement and show their applications. 相似文献
40.
In this work, we present two simple methods to quantify the mobility of dynamic speckle patterns. The first method is based on the averaged pixel intensity differences between subsequent frames, while the second simply counts the fraction of pixels whose intensity changes with time in more than a certain quantity related to background noise. We have analyzed the applicability of these methods to different specimens (inorganic and biological) and compared the results to check their validity. 相似文献