scholarly journals A Method to Optimize the Electron Spectrum for Simulating Thermo-Mechanical Response to X-ray Radiation

Symmetry ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 59
Author(s):  
Xianwen Ran ◽  
Bo Wang ◽  
Kun Zhang ◽  
Wenhui Tang

The X-ray pulse originating from high altitude nuclear detonation (HAND) is mainly soft X-ray and its intensity is high enough to gasify the penetrated material and then lead to the severe thermo-mechanical deformation of unpenetrated material from the gasified blow-off effect. This effect cannot be directly reproduced in a lab for the lack of the X-ray source like HAND. At present, the low-energy relativistic electron beams resulting from an electron accelerator are usually used to approximately reproduce this effect, but the difference in the energy-deposited profile in materials between the electron and X-ray cannot be eliminated. In this paper, the symmetric linear least squares method was used to optimize the electron spectrum, and the general Monte Carlo N-Particle Transport Code calculations showed the optimized spectrum can produce the same energy-deposited profile in aluminum, copper, and tantalum with the soft X-rays like 1 keV or 3 keV spectrums. This indicates that it is possible to simulate the severe thermo-mechanical deformation resulting from HAND using the optimized electron spectrums.

1994 ◽  
Vol 375 ◽  
Author(s):  
C. T. Chen ◽  
Y. U. Idzerda ◽  
C.-C. Kao ◽  
L. H. Tjeng ◽  
H.-J. Lin ◽  
...  

AbstractSoft-x-ray magnetic circular dichroism (MCD) is the difference between the absorptivity or reflectivity of left and right circularly polarized soft-x-rays at the magnetically interesting L2,3- edges of 3d transition metals or the M4,5-edges of the 4f rare earth elements. Thanks to its large absorption cross-section and strong MCD effect, this technique has become a powerful new means for probing, in an element- and site-specific manner, the magnetic properties of ultra-thin films and multilayers. Soft-x-ray MCD experiments, recently conducted at the Dragon beamline, are utilized to demonstrate the recent progress in this technique and its applications in the research of magnetic thin films.


In a previous paper it was shown that 0·0007 per cent, of 29 Cu and 0·0003 per cent, of 26 Fe could be detected in 30 Zn by atomic analysis by X-ray spectroscopy. This sensitivity is greater than that which was claimed by Noddack, Tacke, and Berg, who set the limit at about 0·1 per cent, for non-metals, and by Hevesy, who stated it to be about 0·01 per cent, for an element present in an alloy. It was later suggested by Hevesy that the high value of the sensitivity which we found might result from the fact that some of the alloys we had used were composed of elements of almost equal atomic number, and that the sensitivity would be smaller for a constituent of low atomic number mixed with a major constituent of high atomic number. To elucidate these disagreements we have made further observations of the sensitivity with elements of different atomic number and have investigated the conditions which can influence the sensitivity. The Factors Determining Sensitivity . The detection of one element in a mixture of elements depends upon the identification of its K or L lines in the general spectrum emitted by the mixture under examination. The intensity with which these lines are excited in the target (“excited intensity”) is proportional to the number of atoms of the constituent element excited, i. e ., to its concentration and to the volume of the target in which the cathode ray energy is absorbed. The depth of penetration of the cathode rays is determined by the density of the target material and by their velocity ( i. e ., by the voltage applied to the X-ray tube). Schonland has shown that the range of homogeneous cathode rays in different elements, expressed as a mass per unit area, is approximately constant and is independent of the atomic number of the absorbing element. When their velocity is increased, the cathode rays will penetrate to a greater depth, and therefore a greater number of atoms of all constituents will be ionised. This will increase the “excited intensity” of the lines due to the particular constituent sought equally with those lines of the other elements present. The intensity of a line further depends upon the difference between the voltage applied to the X-ray tube and that necessary to excite the series. For these reasons, a high applied voltage is required for a high sensitivity.


2017 ◽  
Vol 13 (S332) ◽  
pp. 418-424
Author(s):  
Marina G. Rachid ◽  
K. Faquine ◽  
S. Pilling

AbstractC2H4O2 isomers, methyl formate (HCOOCH3), acetic acid (CH3COOH) and glycoaldehyde (HOCH2CHO), have been detected in a lot of sources in ISM. However, their abundances are very different, with methyl formate much more abundant than the other two isomers. This fact may be related to the different destruction by ionizing radiation of these molecules. The goal of this work is experimentally study the photodissociation processes of methyl formate and acetic acid ices when exposed to broadband soft X-ray from 6 up to 2000 eV. The experiments were performed coupled to the SGM beamline in the Brazilian Synchrotron Light Source (LNLS/CNPEM) at Campinas, Brazil. The simulated astrophysical ices (12K) were monitored throughout the experiment using infrared vibrational spectroscopy. The analysis of processed ices allowed the determination of the effective destruction cross sections of the parent molecules as well as the effective formation cross section of daughter molecular species. The relative abundance between acetic acid and methyl formate (NCH3COOH/NHCOOCH3) in different astronomical scenarios and their column density evolution in the presence of X-rays were calculated and our results suggests that such radiation field can be one of the factors that explain the difference in the isomers C2H4O2 abundances. We also quantified the daugther species after the establishment of a chemical equilibrium in the samples.


IAWA Journal ◽  
2009 ◽  
Vol 30 (2) ◽  
pp. 165-178 ◽  
Author(s):  
Daniel Keunecke ◽  
Robert Evans ◽  
Peter Niemz

Yew wood holds a special position within the softwoods with regard to its exceptional elasto-mechanical behaviour. Despite a relatively high density, it is highly elastic in the longitudinal direction (the modulus of elasticity is low and the stretch to break high). In the radial-tangential plane, its elastic anisotropy is clearly less pronounced compared to other softwoods such as spruce. Knowledge of the anatomical organisation of yew wood is an indispensable precondition for the correct interpretation of this conspicuous mechanical behaviour. The aim of this study, therefore, was to interpret the difference in elasto-mechanical behaviour of yew and spruce (as a reference) through their relative microstructures as measured by SilviScan, a technology based on X-ray densitometry, X-ray diffractometry and optical microscopy. This system is able to measure a variety of structural features in a wood sample. The results reveal that the elasto-mechanical response of yew is primarily due to large microfibril angles and a more homogeneous cross-sectional tissue composition (regarding tracheid dimensions and density distribution) compared to spruce. With respect to structure-property relationships, it was concluded that yew wood combines properties of normal and compression wood and therefore takes an intermediate position between them.


1993 ◽  
Vol 308 ◽  
Author(s):  
I. C. Noyan ◽  
G. Sheikh

ABSTRACTThe mechanical response of a specimen incorporating thin films is dictated by a combination of fundamental mechanical parameters such as Young's moduli of the individual layers, and by configurational parameters such as adhesion strength at the interface(s), residual stress distribution and other process dependent factors. In most systems, the overall response will be dominated by the properties of the (much thicker) substrate. Failure within the individual layers, on the other hand, is dependent on the local strain distributions and can not be predicted from the substrate values alone. To better understand the mechanical response of these systems, the strain within the individual layers of the thin film system must be measured and correlated with applied stresses. Phase selectivity of X-ray stress/strain analysis techniques is well suited for this purpose. In this paper, we will review the use of the traditional x-ray stress/strain analysis methods for the determination of the mechanical properties of thin film systems.


2014 ◽  
Vol 996 ◽  
pp. 175-180 ◽  
Author(s):  
Rasha Alkaisee ◽  
Ru Lin Peng

For X-Ray Diffraction Measurement of Depth Profiles of Residual Stress, Step-Wise Removal of Materials has to be Done to Expose the Underneath Layers to the X-Rays. this Paper Investigates the Influence of Layer Removal Methods, Including Electro-Polishing in Two Different Electrolytes and Chemical Etching, on the Accuracy of Residual Stress Measurement. Measurements on Two Shot-Peened Steels Revealed Large Discrepancy in Subsurface Distributions of Residual Stress Obtained with the Respective Methods. Especially, the Chemical Etching Yielded much Lower Subsurface Compressive Stresses than the Electro-Polishing Using a so Called AII Electrolyte. the Difference was Explained by the Influence of the Different Layer Removal Methods on the Microscopic Roughness.


2020 ◽  
Author(s):  
Chloe Coates ◽  
Claire A. Murray ◽  
Hanna Boström ◽  
Emily Reynolds ◽  
Andrew Goodwin

Cadmium cyanide, Cd(CN)<sub>2</sub>, is a flexible coordination polymer best studied for its strong and isotropic negative thermal expansion (NTE) effect. Here we show that this NTE is actually X-ray exposure dependent: Cd(CN)<sub>2</sub> contracts not only on heating but also on irradiation by X-rays. This behaviour contrasts that observed in other beam-sensitive materials, for which X-ray exposure drives lattice expansion. We call this effect ‘negative X-ray expansion’ (NXE) and suggest its origin involves an interaction between X-rays and cyanide ‘flips’; in particular, we rule out local heating as a possible mechanism. Irradiation also affects the nature of a low-temperature phase transition. Our analysis resolves discrepancies in NTE coefficients reported previously on the basis of X-ray diffraction measurements, and we establish the ‘true’ NTE behaviour of Cd(CN)<sub>2</sub> across the temperature range 150–750 K. The interplay between irradiation and mechanical response in Cd(CN)<sub>2</sub> highlights the potential for exploiting X-ray exposure in the design of functional materials.


2021 ◽  
Vol 8 (3) ◽  
pp. 533
Author(s):  
Budi Nugroho ◽  
Eva Yulia Puspaningrum

<p class="Abstrak">Saat ini banyak dikembangkan proses pendeteksian pneumonia berdasarkan citra paru-paru dari hasil foto rontgen (x-ray), sebagaimana juga dilakukan pada penelitian ini. Metode yang digunakan adalah <em>Convolutional Neural Network</em> (CNN) dengan arsitektur yang berbeda dengan sejumlah penelitian sebelumnya. Selain itu, penelitian ini juga memodifikasi model CNN dimana metode <em>Extreme Learning Machine</em> (ELM) digunakan pada bagian klasifikasi, yang kemudian disebut CNN-ELM. Dataset untuk uji coba menggunakan kumpulan citra paru-paru hasil foto rontgen pada Kaggle yang terdiri atas 1.583 citra normal dan 4.237 citra pneumonia. Citra asal pada dataset kaggle ini bervariasi, tetapi hampir semua diatas ukuran 1000x1000 piksel. Ukuran citra yang besar ini dapat membuat pemrosesan klasifikasi kurang efektif, sehingga mesin CNN biasanya memodifikasi ukuran citra menjadi lebih kecil. Pada penelitian ini, pengujian dilakukan dengan variasi ukuran citra input, untuk mengetahui pengaruhnya terhadap kinerja mesin pengklasifikasi. Hasil uji coba menunjukkan bahwa ukuran citra input berpengaruh besar terhadap kinerja klasifikasi pneumonia, baik klasifikasi yang menggunakan metode CNN maupun CNN-ELM. Pada ukuran citra input 200x200, metode CNN dan CNN-ELM menunjukkan kinerja paling tinggi. Jika kinerja kedua metode itu dibandingkan, maka Metode CNN-ELM menunjukkan kinerja yang lebih baik daripada CNN pada semua skenario uji coba. Pada kondisi kinerja paling tinggi, selisih akurasi antara metode CNN-ELM dan CNN mencapai 8,81% dan selisih F1 Score mencapai 0,0729. Hasil penelitian ini memberikan informasi penting bahwa ukuran citra input memiliki pengaruh besar terhadap kinerja klasifikasi pneumonia, baik klasifikasi menggunakan metode CNN maupun CNN-ELM. Selain itu, pada semua ukuran citra input yang digunakan untuk proses klasifikasi, metode CNN-ELM menunjukkan kinerja yang lebih baik daripada metode CNN.</p><p class="Abstrak"> </p><p class="Abstrak"><em><strong>Abstract</strong></em></p><p class="Abstract"><em>This research developed a pneumonia detection machine based on the lungs' images from X-rays (x-rays). The method used is the Convolutional Neural Network (CNN) with a different architecture from some previous research. Also, the CNN model is modified, where the classification process uses the Extreme Learning Machine (ELM), which is then called the CNN-ELM method. The empirical experiments dataset used a collection of lung x-ray images on Kaggle consisting of 1,583 normal images and 4,237 pneumonia images. The original image's size on the Kaggle dataset varies, but almost all of the images are more than 1000x1000 pixels. For classification processing to be more effective, CNN machines usually use reduced-size images. In this research, experiments were carried out with various input image sizes to determine the effect on the classifier's performance. The experimental results show that the input images' size has a significant effect on the classification performance of pneumonia, both the CNN and CNN-ELM classification methods. At the 200x200 input image size, the CNN and CNN-ELM methods showed the highest performance. If the two methods' performance is compared, then the CNN-ELM Method shows better performance than CNN in all test scenarios. The difference in accuracy between the CNN-ELM and CNN methods reaches 8.81% at the highest performance conditions, and the difference in F1-Score reaches 0.0729. This research provides important information that the size of the input image has a major influence on the classification performance of pneumonia, both classification using the CNN and CNN-ELM methods. Also, on all input image sizes used for the classification process, the CNN-ELM method shows better performance than the CNN method.</em></p>


2020 ◽  
Vol 386 (4) ◽  
pp. 6-12
Author(s):  
R. T. Abdraimov ◽  
B. E. Vintaykin ◽  
P. A. Saidakhmetov ◽  
N. K. Madiyarov ◽  
M. A. Abdualiyeva

Algorithms for solving typical mineralogical problems associated with quantitative x-ray spectral analysis and quantitative x-ray phase analysis using the program “Origin” are developed. The calculation of the areas and midpoint of spectral lines using the tabular processor of the program “Origin” is considered. Various approaches to determining the parameters of spectral lines using the least squares method using the standard functions of the program “Origin” were tested. The creation of a user function for approximation of diffraction maxima by the Cauchy function taking into account the doublet character of Ka series of x-rays is also considered. Various built-in algorithms for smoothing functions (based on averaging, polynomial approximation and Fourier analysis – synthesis) were tested to find weak diffraction maxima against strong noise; optimal schemes for the application of these algorithms were found. The considered algorithms can be applied in universities when processing the results of laboratory works on the topics "Analysis of spectra of emission of atoms", "Quantitative x-ray spectral analysis" and "Quantitative x-ray phase analysis".


1979 ◽  
Vol 23 ◽  
pp. 125-131
Author(s):  
L. A. Rayburn

AbstractOne of the uncertain aspects in the analysis of x-ray spectra is the determination of the proper background to subtract from the raw data. In those cases where the background is a smoothly varying funct ion of the x-ray energy, the application of a digital filter to the raw data will effectively remove the background leaving only the filtered peak information. These filtered peaks can then be fit by using a non-linear least squares method in conjunction with a suitably chosen mathematical model of the peak structure.


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