共查询到20条相似文献,搜索用时 93 毫秒
1.
We have developed an automated data analysis method for atmospheric particles using scanning transmission X-ray microscopy coupled with near edge X-ray fine structure spectroscopy (STXM/NEXAFS). This method is applied to complex internally mixed submicrometer particles containing organic and inorganic material. Several algorithms were developed to exploit NEXAFS spectral features in the energy range from 278 to 320 eV for quantitative mapping of the spatial distribution of elemental carbon, organic carbon, potassium, and noncarbonaceous elements in particles of mixed composition. This energy range encompasses the carbon K-edge and potassium L2 and L3 edges. STXM/NEXAFS maps of different chemical components were complemented with a subsequent analysis using elemental maps obtained by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX). We demonstrate the application of the automated mapping algorithms for data analysis and the statistical classification of particles. 相似文献
2.
E. A. Artyukhin A. V. Nenarokomov A. P. Tryanin S. A. Utenkov V. V. Yakovlev 《Journal of Engineering Physics and Thermophysics》1992,63(1):742-748
The results of experimental computational detemination of contact thermal resitances (CTR) between the heat-evolving cores anf jackets of nuclear fuel elements are presented. The dependence of the CTR magnitude on the linear heat loading of the fuel element is analyzed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 1, pp. 114–121, July, 1992. 相似文献
3.
O. P. Lazukina E. N. Volkova K. K. Malyshev M. F. Churbanov 《Inorganic Materials》2008,44(11):1266-1271
By the example of chemical elements in the form of elementary substance it was shown that the total content of elemental impurities can be considered as an objective and generalized index of the purity of individual matter. Impurity composition of the volatile compounds evaluated on the experimental results was presented in the form of two information files: (i) the content of chemical elements for low-volatile impurities, and (ii) the content of impurities with specified molecular structure (taking into account that the volatility of impurity and base is comparable). A unified approach to the presentation of the impurity composition data of volatile compounds, which considers the elemental composition of both groups of impurities and allows estimating of the total content of elemental impurities in compound, has been developed. In the framework of this approach the average total impurity content of the high-purity volatile chloride samples, which are available at the Collection Exhibition of Special Purity Substances, were evaluated. 相似文献
4.
Capabilities of surface composition analysis using a long laser-induced breakdown spectroscopy spark
An apparatus has been investigated based on laser-induced breakdown spectroscopy (LIBS) for the rapid determination of the spatial distribution of elements on surfaces. Cylindrical optics are used to create a linear spark approximately 1 cm in length. Light emitted by atoms excited along the spark is collected and provides a spatial profile of elemental composition in the sample when analyzed with a spectrometer and gated charge-coupled device (ICCD) detector. Moving the spark across the sample surface as spectral data is recorded at regularly spaced intervals allows for the development of a three-dimensional elemental distribution map (emission intensity versus spatial distribution across an area). An analysis of the spatial resolution of this methodology is presented along with representative data from several sample types. Application of full-image analysis allowing for simultaneous investigations into the spatial distributions of multiple elements is also discussed and results are presented. 相似文献
5.
The influence of various treatments on the chemical state of the GaAs surface is considered. The formation and removal of
an elemental arsenic layer and gallium and arsenic oxides, sulfurization of the surface, and its passivation with elemental
arsenic are studied as functions of etchant composition and pH, etching kinetics, electrode potential, anodic polarization,
and conditions of subsequent rinsing. 相似文献
6.
悬索桥结构分析中索鞍的精确模拟 总被引:3,自引:0,他引:3
为在悬索桥结构分析中精确模拟索鞍,建立了索段一端固定于鞍座上的两节点“左鞍座单元”和“右鞍座单元”,以及索段中一点固定于鞍座上的三节点“鞍座单元”,此固定点为新单元的一个节点。它们通过自动调整索与鞍座的切点而处于平衡状态,从而简化了计算。单元算法的推导基于有限元分析的基本原理和弹性悬链线的精确解,并利用了处于平衡状态时索与鞍座之间的内力关系。新单元可以考虑鞍座重量的影响,鞍槽纵向曲线可为复合圆曲线。新单元可以同常规单元一样直接用于索结构的有限元分析,设计的算例验证了其正确性,工程算例显示了其在悬索桥结构分析中的应用。 相似文献
7.
A laser microscope system for the microanalytical characterization of complex materials is described. The universal measuring principle of laser-induced breakdown spectroscopy (LIBS) in combination with echelle optics permits a fast simultaneous multielement analysis with a possible spatial resolution below 10 pm. The developed system features completely UV-transparent optics for the laser-microscope coupling and the emission beam path and enables parallel signal detection within the wavelength range of 200-800 nm with a spectral resolution of a few picometers. Investigations of glass defects and tool steels were performed. The characterization of a glass defect in a tumbler by a micro-LIBS line scan, with use of a 266-nm diode-pumped Nd:YAG laser for excitation, is possible by simple comparison of plasma spectra of the defect and the surrounding area. Variations in the main elemental composition as well as impurities by trace elements are detected at the same time. Through measurement of the calibration samples with the known concentration of the corresponding element, a correlation between the intensity of spectral lines and the element concentration was also achieved. The change of elemental composition at the transient stellite solder of tool steels has been determined by an area scan. The two-dimensional pictures show abrupt changes of the element distribution along the solder edge and allow fundamental researches of dynamic modifications (e.g., diffusion) in steel. 相似文献
8.
O. I. Bilyy O. V. Ishchenko V. E. Diyuk L. D. Kisters’ka O. B. Loginova V. M. Tkach 《Journal of Superhard Materials》2018,40(3):189-196
Electron-microscopic study of the state (size distribution and the elemental composition) of nanoparticles based on Fe and Fe–Co on the surface of the carbon fiber (CF) deposited from colloidal solution by the chemical deposition and direct dispersion in plasma. The work of the carbon fiber modified by nanoparticles of metals of carbon fibers as anodes in the laboratory two-chamber microbial–anodic cell of the fuel element based on the bacterium Desulfuromonas acetoxidans was studied. The expediency of the practical use in anodes of microbial fuel cells of nanoparticles Fe was proved. 相似文献
9.
R D K Misra A B Pandey V V Rama Rao Mahendra Kumar 《Bulletin of Materials Science》1988,11(4):337-346
A new experimental approach to the evaluation of chemical segregation of solute elements in ultrasonically gas atomized aluminium-alloy
powders using X-ray spectral data of scanning electron microprobe analyser is described. The experimentally obtained chemical
segregation data is compared with the conventional method of quantitative analysis and with theoretical predictions as determined
from Scheil’s approach to the evaluation of elemental segregation during the solidification process. A comparison of experimental
and theoretical predictions confirms the validity of the experimental approach in the estimation of solute segregation levels
and also suggests that the solidification conditions considered for estimation of microchemical segregation can appropriately
be applied to ultrasonically gas atomized powders. 相似文献
10.
Jong‐Shyong Wu Lieh‐Kwang Chiang 《International journal for numerical methods in engineering》2003,58(13):1907-1936
The natural frequencies and mode shapes for the radial (in‐plane) bending vibrations of the uniform circular arches were investigated by means of the finite arch (curved beam) elements. Instead of the complicated explicit shape functions of the arch element given by the existing literature, the simple implicit shape functions associated with the tangential, radial (or normal) and rotational displacements of the arch element were derived and presented in matrix form. Based on the relationship between the nodal forces and the nodal displacements of a two‐node six‐degree‐of‐freedom arch element, the elemental stiffness matrix was derived, and based on the equation of kinetic energy and the implicit shape functions of an arch element the elemental consistent mass matrix with rotary inertia effect considered was obtained. Assembly of the foregoing elemental property matrices yields the overall stiffness and mass matrices of the complete curved beam. The standard techniques were used to determine the natural frequencies and mode shapes for the curved beam with various boundary conditions and subtended angles. In addition to the typical circular arches with constant curvatures, a hybrid beam constructed by using an arch segment connected with a straight beam segment at each of its two ends was also studied. For simplicity, a lumped mass model for the arch element was also presented. All numerical results were compared with the existing literature or those obtained from the finite element method based on the conventional straight beam element and good agreements were achieved. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
11.
Evaluation of the emission characteristics of trace metals from coal and fuel oil fired power plants and their fate during combustion 总被引:1,自引:0,他引:1
Coal as well as fuel oil combustion generates emissions of potentially toxic trace pollutants including organic and inorganic chemical compounds besides major pollutants. A study on As, Cd, Co, Cr, Cu, Hg, Fe, Mn, Ni, Pb, Se, and Zn emissions from a 220 MW coal-fired power plant equipped with a electrostatic precipitators (ESPs) and 6 MW oil fired-power plant was carried out, using stack monitoring kit, Envirotech APM 620, which is similar to EPA Method 29. Simultaneous sampling of coal, fuel oil, oil waste, bottom ash, fly ash, flue gases, and particles associated with the gas phase has been performed. This sampling method was used for trace metal sampling. The content of all these metals in coal, oil, oil waste, bottom ash, fly ash have been determined by XRF, whereas their contents in the flue gases, and particles associated with the gas phase has been analyzed with ICP-AES. The mass balances obtained for trace elements were satisfactory in case of fuel oil based power plant, whereas in case of coal fired power plant, the mass balance for all the trace elements were below 50% except for the As, Se, and Hg. The enrichment factors for all trace metals was <1 in both cases. The above sampling method is moderately adequate method for trace element sampling in coal as well as oil fired power plants except for Hg. The results indicate that trace metals emissions were higher in coal-based power plant than the fuel oil-fired power plant. 相似文献
12.
A versatile Monte Carlo program for quantitative particle analysis in electron probe X-ray microanalysis is presented. The program includes routines for simulating electron-solid interactions in microparticles lying on a flat surface and calculating the generated X-ray signal. Simulation of the whole X-ray spectrum as well as phi(z) curves is possible. The most important facility of the program is the reverse Monte Carlo quantification of the chemical composition of microparticles, including low-Z elements, such as C, N, O, and F. This quantification method is based on the combination of a single scattering Monte Carlo simulation and a robust successive approximation. An iteration procedure is employed; in each iteration step, the Monte Carlo simulation program calculates characteristic X-ray intensities, and a new set of concentration values for chemical elements in the particle is determined. When the simulated X-ray intensities converge to the measured ones, the input values of elemental concentrations used for the simulation are determined as chemical compositions of the particle. This quantification procedure was evaluated by investigating various types of standard particles, and good accuracy of the methodology was demonstrated. A methodology for heterogeneity assessment of single particles is also described. 相似文献
13.
M. R. Alexander R. D. Short F. R. Jones M. Stollenwerk J. Zabold W. Michaeli 《Journal of Materials Science》1996,31(7):1879-1885
The effect of oxygen addition to microwave-sustained plasmas of hexamethyldisiloxane (HMDSO) has been investigated. Attention was directed to the solid products formed on aluminium substrates (plasma deposits). To enable a quantitative analysis of these, X-ray photoelectron spectroscopy (XPS) of standard silicon-containing materials was carried out. When suitable charge correction is applied to the XP spectra of HMDSO/O2 plasma deposits, a number of very clear trends emerge. From changes in elemental composition, core line binding energies (Si2p, C 1s, and O 1s) and widths, we show how oxygen addition to the plasma affects the chemical nature of the plasma deposit. The data reported also provide (some limited) information on the reactions taking place in the plasma. 相似文献
14.
The working process in the regenerative gas generators of liquid rocket engines is analyzed and a method for computer simulation based on the Zel’dovich’s model of “quenching” the composition of the products of high-temperature combustion as a result of rapid cooling on supplying an excess of the low-temperature component and the resulting chemical quasi-nonequilibrium is developed. The method is implemented and tested on the basis of the TERRA software package in calculations of the composition and properties of the propellant produced by regenerative gas generators using oxygen as the oxidizer and methane as the fuel. The vacuum specific impulse of the considered fuel is calculated for the possible conditions of a quasi-nonequilibrium working process. 相似文献
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17.
N. I. Baklanova T. M. Zima A. T. Titov N. V. Isaeva D. V. Grashchenkov S. S. Solntsev 《Inorganic Materials》2006,42(7):744-749
Protective refractory nanocoatings on carbon bundles and tapes have been investigated. Processes have been developed for growing thin layers of refractory oxides—alumina, zirconia, and silica—on continuous carbon fibers and tapes using sol-gel processing. ZrC/ZrO2 bilayer coatings have been produced by chemical vapor transport. The surface morphology, phase composition, and elemental composition of the coatings have been studied by x-ray diffraction, high-resolution scanning electron microscopy, and qualitative energy-dispersive x-ray microanalysis. The results demonstrate that the refractory oxide coatings are homogeneous along the length and perimeter of individual fibers and adhere well to the fiber surface, with no peeling. Their thickness is within 200–300 nm. The effect of the nature of the coating on the oxidation resistance of carbon materials is analyzed. 相似文献
18.
Pyrolysis characteristics of integrated circuit boards at various particle sizes and temperatures 总被引:2,自引:0,他引:2
A pyrolysis method was employed to recycle the metals and brominated compounds blended into printed circuit boards. This research investigated the effect of particle size and process temperature on the element composition of IC boards and pyrolytic residues, liquid products, and water-soluble ionic species in the exhaust, with the overall goal being to identify the pyrolysis conditions that will have the least impact on the environment. Integrated circuit (IC) boards were crushed into 5-40 mesh (0.71-4.4mm), and the crushed particles were pyrolyzed at temperatures ranging from 200 to 500 degrees C. The thermal decomposition kinetics were measured by a thermogravimetric (TG) analyzer. The composition of pyrolytic residues was analyzed by Energy Dispersive X-ray Spectrometer (EDS), Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). In addition, the element compositions of liquid products were analyzed by ICP-AES and ICP-MS. Pyrolytic exhaust was collected by a water-absorption system in an ice-bath cooler, and IC analysis showed that the absorbed solution comprised 11 ionic species. Based on the pyrolytic kinetic parameters of TG analysis and pyrolytic residues at various temperatures for 30 min, the effect of particle size was insignificant in this study, and temperature was the key factor for the IC board pyrolysis. Two stages of decomposition were found for IC board pyrolysis under nitrogen atmosphere. The activation energy was 38-47 kcal/mol for the first-stage reaction and 5.2-9.4 kcal/mol for the second-stage reaction. Metal content was low in the liquid by-product of the IC board pyrolysis process, which is an advantage in that the liquid product could be used as a fuel. Brominate and ammonium were the main water-soluble ionic species of the pyrolytic exhaust. A plan for their safe and effective disposal must be developed if the pyrolytic recycling process is to be applied to IC boards. 相似文献
19.
A facile and universal synthetic approach for preparing superlattice nanowire (SLNW) arrays is developed. In this method, two kinds of elements are alternately electrodeposited into the holes of the anodic alumina oxide (AAO) template, automatically in separate electrolytes by a programmed device. This method is not restricted by the relative values of the reduction potentials of the elements, and the deposition of each element can be controlled independently. Three kinds of representative SLNW arrays containing noble-metal material (Ag/Ni), thermoelectric material (Bi/Sb) and magnetic material (Ni/Cu) with adjustable segment length are fabricated successfully. 相似文献
20.
Three-dimensional (3D) X-ray imaging methods have advanced tremendously during recent years. Traditional tomography uses absorption as the contrast mechanism, but for many purposes its sensitivity is limited. The introduction of diffraction, small-angle scattering, refraction, and phase contrasts has increased the sensitivity, especially in materials composed of light elements (for example, carbon and oxygen). X-ray spectroscopy, in principle, offers information on element composition and chemical environment. However, its application in 3D imaging over macroscopic length scales has not been possible for light elements. Here we introduce a new hard-X-ray spectroscopic tomography with a unique sensitivity to light elements. In this method, dark-field section images are obtained directly without any reconstruction algorithms. We apply the method to acquire the 3D structure and map the chemical bonding in selected samples relevant to materials science. The novel aspects make this technique a powerful new imaging tool, with an inherent access to the molecular-level chemical environment. 相似文献