Gradual hard X-ray events and second phase particle acceleration

Solar Physics ◽  
1984 ◽  
Vol 90 (1) ◽  
pp. 133-138 ◽  
Author(s):  
S. W. Kahler
Keyword(s):  
Particle Acceleration ◽  
Phase Particle ◽  
Second Phase ◽  
X Ray

scholarly journals When will Low-Contrast Features be Visible in a STEM X-Ray Spectrum Image?

2015 ◽  
Vol 21 (3) ◽  
pp. 706-724 ◽  
Author(s):  
Chad M. Parish
Keyword(s):  
Phase Particle ◽  
General Procedure ◽  
Second Phase ◽  
Steel Matrix ◽  
Shell Nanoparticles ◽  
Ferritic Alloy ◽  
Electron Dose ◽  
Data Set ◽  
Low Contrast ◽  
X Ray

AbstractWhen will a small or low-contrast feature, such as an embedded second-phase particle, be visible in a scanning transmission electron microscopy (STEM) X-ray map? This work illustrates a computationally inexpensive method to simulate X-ray maps and spectrum images (SIs), based upon the equations of X-ray generation and detection. To particularize the general procedure, an example of nanostructured ferritic alloy (NFA) containing nm-sized Y2Ti2O7 embedded precipitates in ferritic stainless steel matrix is chosen. The proposed model produces physically appearing simulated SI data sets, which can either be reduced to X-ray dot maps or analyzed via multivariate statistical analysis. Comparison to NFA X-ray maps acquired using three different STEM instruments match the generated simulations quite well, despite the large number of simplifying assumptions used. A figure of merit of electron dose multiplied by X-ray collection solid angle is proposed to compare feature detectability from one data set (simulated or experimental) to another. The proposed method can scope experiments that are feasible under specific analysis conditions on a given microscope. Future applications, such as spallation proton–neutron irradiations, core-shell nanoparticles, or dopants in polycrystalline photovoltaic solar cells, are proposed.

Simulation of Damage Percolation Within Aluminum Alloy Sheet

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
O. S. Orlov ◽  
M. J. Worswick ◽  
E. Maire ◽  
D. J. Lloyd
Keyword(s):  
Aluminum Alloy ◽  
Void Nucleation ◽  
Phase Particle ◽  
Three Dimensional ◽  
Alloy Sheet ◽  
Void Coalescence ◽  
Second Phase ◽  
X Ray ◽  
Damage Initiation

A combined experimental and analytical approach is used to study damage initiation and evolution in three-dimensional second phase particle fields. A three-dimensional formulation of a damage percolation model is developed to predict damage nucleation and propagation through random-clustered second phase particle fields. The proposed approach is capable of capturing the three-dimensional character of damage phenomena and the three stages of ductile fracture, namely, void nucleation, growth, and coalescence, at the level of discrete particles. An in situ tensile test with X-ray tomography is utilized to quantify material damage during deformation in terms of the number of nucleated voids and porosity. The results of this experiment are used for both the development of a clustering-sensitive nucleation criterion and the validation of the damage percolation predictions. The evolution of damage in aluminum alloy AA5182 has been successfully predicted to match that in the in situ tensile specimen. Two forms of second phase particle field input data were considered: (1) that measured directly with X-ray tomography and (2) fields reconstructed statistically from two-dimensional orthogonal sections. It is demonstrated that the adoption of a cluster-sensitive void nucleation criterion, as opposed to a cluster-insensitive nucleation criterion, has a significant effect in promoting predicted void nucleation to occur within particle clusters. This behavior leads to confinement of void coalescence to within clusters for most of the duration of deformation followed by later development of a macrocrack through intracluster coalescence. The measured and reconstructed second phase particle fields lead to similar rates of predicted damage accumulation and can be used interchangeably in damage percolation simulations.

Analytical Electron Microscopy Study of Second-Phase Particles in 7075 and 7475 Aluminum Alloys

1985 ◽  
Vol 43 ◽  
pp. 348-349
Author(s):  
M. Raghavan ◽  
J. Y. Koo ◽  
J. W. Steeds ◽  
B. K. Park
Keyword(s):  
Aluminum Alloys ◽  
Silicon Oxide ◽  
Analytical Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Partial Substitution ◽  
Second Phase ◽  
X Ray ◽  
Second Phase Particles ◽  
Almost All

X-ray microanalysis and Convergent Beam Electron Diffraction (CBD) studies were conducted to characterize the second phase particles in two commercial aluminum alloys -- 7075 and 7475. The second phase particles studied were large (approximately 2-5μm) constituent phases and relatively fine ( ∼ 0.05-1μn) dispersoid particles, Figures 1A and B. Based on the crystal structure and chemical composition analyses, the constituent phases found in these alloys were identified to be Al7Cu2Fe, (Al,Cu)6(Fe,Cu), α-Al12Fe3Si, Mg2Si, amorphous silicon oxide and the modified 6Fe compounds, in decreasing order of abundance. The results of quantitative X-ray microanalysis of all the constituent phases are listed in Table I. The data show that, in almost all the phases, partial substitution of alloying elements occurred resulting in small deviations from the published stoichiometric compositions of the binary and ternary compounds.

scholarly journals XCOVNet: Chest X-ray Image Classification for COVID-19 Early Detection Using Convolutional Neural Networks

2021 ◽  
Author(s):  
Vishu Madaan ◽  
Aditya Roy ◽  
Charu Gupta ◽  
Prateek Agrawal ◽  
Anand Sharma ◽  
...  
Keyword(s):  
Image Classification ◽  
Second Phase ◽  
Two Phase ◽  
X Ray ◽  
The Neural Network ◽  
Rapid Spread ◽  
Chest X Ray ◽  
Polymerase Chain ◽  
Two Phases ◽  
Active Patients

AbstractCOVID-19 (also known as SARS-COV-2) pandemic has spread in the entire world. It is a contagious disease that easily spreads from one person in direct contact to another, classified by experts in five categories: asymptomatic, mild, moderate, severe, and critical. Already more than 66 million people got infected worldwide with more than 22 million active patients as of 5 December 2020 and the rate is accelerating. More than 1.5 million patients (approximately 2.5% of total reported cases) across the world lost their life. In many places, the COVID-19 detection takes place through reverse transcription polymerase chain reaction (RT-PCR) tests which may take longer than 48 h. This is one major reason of its severity and rapid spread. We propose in this paper a two-phase X-ray image classification called XCOVNet for early COVID-19 detection using convolutional neural Networks model. XCOVNet detects COVID-19 infections in chest X-ray patient images in two phases. The first phase pre-processes a dataset of 392 chest X-ray images of which half are COVID-19 positive and half are negative. The second phase trains and tunes the neural network model to achieve a 98.44% accuracy in patient classification.

Nanostructured TiO2-Based Composites for Light Absorption

2014 ◽  
Vol 975 ◽  
pp. 207-212
Author(s):  
Dayse I. dos Santos ◽  
Olayr Modesto Jr. ◽  
Luis Vicente A. Scalvi ◽  
Americo S. Tabata
Keyword(s):  
Metal Oxide ◽  
Light Absorption ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Oxide Powders

Metal oxide nanocomposites were prepared by two different routes: polyol and sol-gel. Characterization by X ray diffraction showed that the first process produces directly a two-phase material, while the sol-gel powder never showed second phase below 600°C. Light spectroscopy of the treated powders indicated similarities for the processed materials. Although the overall material compositions are about the same, different structural characteristics are found for each processing. With the exception of Ti-Zn materials, all the double metal oxide powders showed higher absorbance than either TiO2 powder.

Diffusional relaxation around a second phase particle

1980 ◽  
Vol 28 (3) ◽  
pp. 319-325 ◽  
Author(s):  
T. Mori ◽  
M. Okabe ◽  
T. Mura
Keyword(s):  
Phase Particle ◽  
Second Phase ◽  
Diffusional Relaxation

scholarly journals Grain Refinement by Second Phase Particles under Applied Stress in ZK60 Mg Alloy with Y through Phase Field Simulation

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1903 ◽  
Author(s):  
Yuhao Song ◽  
Mingtao Wang ◽  
Yaping Zong ◽  
Ri He ◽  
Jianfeng Jin
Keyword(s):  
Grain Refinement ◽  
Applied Stress ◽  
Phase Field ◽  
Phase Particle ◽  
Alloy System ◽  
Second Phase ◽  
Recrystallization Process ◽  
Time Space ◽  
Second Phase Particles ◽  
Zk60 Alloy

Based on the principle of grain refinement caused by the second-phase particles, a phase field model was built to describe the recrystallization process in the ZK60 alloy system with Y added under applied stress between temperatures 573 and 673 K for 140 min duration. The simulation of grain growth with second phase particles and applied stress during annealing process on industrial scale on the condition of real time-space was achieved. Quantitative analysis was carried out and some useful laws were revealed in ZK60 alloy system. The second phase particles had a promoting effect on the grain refinement, however the effect weakened significantly when the content exceeded 1.5%. Our simulation results reveal the existence of a critical range of second phase particle size of 0.3–0.4 μm, within which a microstructure of fine grains can be obtained. Applied stress increased the grain coarsening rate significantly when the stress was more than 135 MPa. The critical size of the second phase particles was 0.4–0.75 μm when the applied stress was 135 MPa. Finally, a microstructure with a grain size of 11.8–13.8 μm on average could be obtained when the second phase particles had a content of 1.5% and a size of 0.4–0.75 μm with an applied stress less than 135 Mpa after 30 min annealing at 573 K.

Depth Profile of Structure, Strain, and Composition in an Annealed Al-Cu-Fe-Cr Quasicrystalline Film

2001 ◽  
Vol 695 ◽  
Author(s):  
M.J. Daniels ◽  
D. King ◽  
J.S. Zabinski ◽  
Z.U. Rek ◽  
J.C. Bilello
Keyword(s):  
Residual Strain ◽  
Incident Angle ◽  
Rf Sputtering ◽  
Strain Analysis ◽  
Grazing Incidence ◽  
Grain Structure ◽  
Second Phase ◽  
Secondary Phases ◽  
Composite Target ◽  
X Ray

ABSTRACTQuasicrystalline films were formed by RF sputtering from a powder composite target onto Inconel substrates, which produces a polymorphic nanoquasicrystalline grain structure, ~2.5 - 10 nm. Subsequent annealing at 500°C for 4 hours, at base pressures of below 5*10-5 Torr, and with Ar flow to 5 - 10 mT, fully develops the quasicrystalline structure with decagonal phase predominating, except near the termination surface. Analysis by XPS indicated extensive oxygen incorporation and limited aluminum enrichment at the termination surface. These results are correlated with structure and strain analysis via synchrotron grazing incidence x-ray scattering (GIXS). By varying the incident angle, hence the x-ray penetration depth, the evolution of an amorphous and crystalline crystalline secondary phases at the surface of the film has been detected. Residual strain analysis shows that this second phase induces a compressive residual strain of 0.10% as measured from the displacement of the major quasicrystalline peaks in the surface layers of the film.

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