Stacking Fault Contrast in an Ordered L12 Lattice

1968 ◽  
Vol 26 ◽  
pp. 260-261
Author(s):  
J. M. Oblak ◽  
B. H. Kear
Keyword(s):  
Phase Shift ◽  
Nearest Neighbor ◽  
Antiphase Boundary ◽  
Stacking Fault ◽  
The Other ◽  
Diffraction Vector ◽  
Physical Difference ◽  
Close Packed Plane ◽  
Other Hand ◽  
Fundamental Reflection

Stacking fault contrast arises from the phase shift α = 2π ḡ · experienced by the diffracted wave at the fault. In an ordered L12 lattice, the displacement <111> is not necessarily equivalent to a displacement of the type <112>. 1 and 2 differ by a displacement <110> which can introduce a phase shift of π when ḡ is a superlattice diffraction vector. The physical difference can be seen by examining the formation of an intrinsic fault. When the fault is produced by removal of a close packed plane, <111>, no nearest neighbor violations of order result; on the other hand,nearest neighbor order is disrupted by shear of the <112> type.Similarly, there are two types of extrinsic faults. Values of α are listed in Table I for [111] and [112] with ḡ of the form 100, 200, and 300. As expected, the two representations are equivalent when ḡ is a fundamental reflection. For g = 100, 010 the values of α for 1 and 2 differ by π because of the antiphase boundary associated with the latter displacement.

Fourier finite‐difference migration

Geophysics ◽  
1994 ◽  
Vol 59 (12) ◽  
pp. 1882-1893 ◽  
Author(s):  
Dietrich Ristow ◽  
Thomas Rühl
Keyword(s):  
Phase Shift ◽  
Finite Difference ◽  
Difference Operator ◽  
Shift Operator ◽  
Velocity Model ◽  
Downward Continuation ◽  
The Other ◽  
Finite Difference Schemes ◽  
Other Hand ◽  
Arbitrary Velocity

Many existing migration schemes cannot simultaneously handle the two most important problems of migration: imaging of steep dips and imaging in media with arbitrary velocity variations in all directions. For example, phase‐shift (ω, k) migration is accurate for nearly all dips but it is limited to very simple velocity functions. On the other hand, finite‐difference schemes based on one‐way wave equations consider arbitrary velocity functions but they attenuate steeply dipping events. We propose a new hybrid migration method, named “Fourier finite‐difference migration,” wherein the downward‐continuation operator is split into two downward‐continuation operators: one operator is a phase‐shift operator for a chosen constant background velocity, and the other operator is an optimized finite‐difference operator for the varying component of the velocity function. If there is no variation of velocity, then only a phase‐shift operator will be applied automatically. On the other hand, if there is a strong variation of velocity, then the phase‐shift component is suppressed and the optimized finite‐difference operator will be fully applied. The cascaded application of phase‐shift and finite‐difference operators shows a better maximum dip‐angle behavior than the split‐step Fourier migration operator. Depending on the macro velocity model, the Fourier finite‐difference migration even shows an improved performance compared to conventional finite‐difference migration with one downward‐continuation step. Finite‐difference migration with two downward‐continuation steps is required to reach the same migration performance, but this is achieved with about 20 percent higher computation costs. The new cascaded operator of the Fourier finite‐difference migration can be applied to arbitrary velocity functions and allows an accurate migration of steeply dipping reflectors in a complex macro velocity model. The dip limitation of the cascaded operator depends on the variation of the velocity field and, hence, is velocity‐adaptive.

scholarly journals Shallow Classifier with Sampling for Sleep Stage Classification of Autism Patients

2018 ◽  
Vol 7 (4.44) ◽  
pp. 194
Author(s):  
Intan Nurma Yulita ◽  
Mohamad Ivan Fanany ◽  
Aniati Murni Arymurthy
Keyword(s):  
Sleep Disorders ◽  
Nearest Neighbor ◽  
Sleep Stage ◽  
The Other ◽  
Sleep Stages ◽  
K Nearest Neighbor ◽  
Class Imbalance Problem ◽  
Other Hand ◽  
Stage Classification ◽  
Sleep Stage Classification

Autism is a brain development disorder that affects the patient's ability to communicate and interact with others. Most people with autism get sleep disorders. But they have some difficulty to communicate, so this problem is getting worse. The alternative that can be done is to detect sleep disorders through polysomnography. One of the test purposes is to classify the sleep stages. The doctors need a long time to process it. This paper presents an automatic sleep stage classification. The classification was based on the shallow classifiers, namely naive Bayes, k-nearest neighbor (KNN), multi-layer perceptron (MLP), and C4.5 (a type of decision tree). On the other hand, this dataset has a class imbalance problem. As a solution, this study carried out the mechanism of resampling. The results show that the use of d as a measure of the uniformity of data distribution greatly influenced the classification performance. The higher d, the more uniform the distribution of data (0 <= d <= 1). The performance with d = 1 was higher than d = 0. On the other hand, KNN was the best classifier. The highest accuracy and F-measure were 83.07 and 82.80 respectively. 

Effect of Surface Etching Conditions on Stacking Faults in 4H-SiC Epitaxy

2019 ◽  
Vol 963 ◽  
pp. 119-122
Author(s):  
Tawhid Rana ◽  
Gil Yong Chung ◽  
Steve Anderson ◽  
Ian Manning ◽  
Willie Bowen ◽  
...  
Keyword(s):  
Stacking Faults ◽  
Gas Mixtures ◽  
Stacking Fault ◽  
High Density ◽  
Experimental Results ◽  
The Other ◽  
Surface Etching ◽  
Other Hand ◽  
Effect Of Surface

Epilayers grown on substrates etched by various etching conditions were studied for stacking fault defects. Substrates were etched by H2, H2+ HCl and H2 + CxHy gases prior to epilayer growth for comparison. High density of SF was observed in the epilayers when H2+HCl or H2+CxHy gas mixtures were used. On the other hand, much lower density of stacking faults (SF) (<1 cm-2) was observed in the epilayer grown on the surface etched by only H2 gas. However, a high number of pits were generated in the epilayer grown on substrate etched by H2 only, which can be considered to be tradeoff of achieving low SF in epilayer by substrate etching. We also conclude from our experimental results that C rich surface is more favorable to generate SF in epilayer compared to Si rich surface.

Nearest neighbors and Voronoi regions in certain point processes

1983 ◽  
Vol 15 (04) ◽  
pp. 726-751 ◽  
Author(s):  
C. M. Newman ◽  
Y. Rinott ◽  
A. Tversky
Keyword(s):  
Point Processes ◽  
Random Number ◽  
Nearest Neighbor ◽  
Nearest Neighbors ◽  
Poisson Processes ◽  
The Other ◽  
Other Hand ◽  
Voronoi Regions ◽  
Dimensional Cube

We investigate, for several models of point processes, the (random) number N of points which have a given point as their nearest neighbor. The largedimensional limit of Poisson processes is treated by considering for n points independently and uniformly distributed in a d-dimensional cube of volume n and showing that Poisson (λ= 1). An asymptotic Poisson (λ= 1) distribution also holds for many of the other models. On the other hand, we find that . Related results concern the (random) volume, , of a Voronoi polytope (or Dirichlet cell) in the cube model; we find that while

scholarly journals Nonhomogeneous random walks systems on ℤ

2010 ◽  
Vol 47 (02) ◽  
pp. 562-571
Author(s):  
Elcio Lebensztayn ◽  
Fábio Prates Machado ◽  
Mauricio Zuluaga Martinez
Keyword(s):  
Random Walk ◽  
Random Walks ◽  
Nearest Neighbor ◽  
The Other ◽  
Active Particle ◽  
Positive Probability ◽  
Small Probability ◽  
Active Particles ◽  
Other Hand ◽  
The Right

We consider a random walks system on ℤ in which each active particle performs a nearest-neighbor random walk and activates all inactive particles it encounters. The movement of an active particle stops when it reaches a certain number of jumps without activating any particle. We prove that if the process relies on efficient particles (i.e. those particles with a small probability of jumping to the left) being placed strategically on ℤ, then it might survive, having active particles at any time with positive probability. On the other hand, we may construct a process that dies out eventually almost surely, even if it relies on efficient particles. That is, we discuss what happens if particles are initially placed very far away from each other or if their probability of jumping to the right tends to 1 but not fast enough.

scholarly journals Herramienta para el cálculo del factor de potencia y capacitores compensadores vectoriales en cargas inductivas

2019 ◽  
pp. 1-5
Author(s):  
Sergio Alejandro Villa-Aviña ◽  
Efrain Villalvazo-Laureano ◽  
Enrique Carlos Rosales-Busquets ◽  
Juan Miguel González-López
Keyword(s):  
Phase Shift ◽  
Power Factor ◽  
Single Phase ◽  
Compensation System ◽  
The Other ◽  
Current Phase ◽  
Electric Networks ◽  
Other Hand ◽  
Made In

In the present work, a power factor (PF) calculation tool for single-phase electric networks is shown. This tool is made in Matlab and Simulink; it contains several useful functions such as the condenser code to achieve the desired result, from the measured value to the unit. It is also possible to visualize the voltage and current phase shift when the system is in the compensation system and its decrease as the PF approaches the unit. On the other hand, it is worth noting the decrease in current by the increase of the PF or compensation. All benefits can be seen graphically for a better understanding of possible compensation solutions.

scholarly journals Nonhomogeneous random walks systems on ℤ

2010 ◽  
Vol 47 (2) ◽  
pp. 562-571 ◽  
Author(s):  
Elcio Lebensztayn ◽  
Fábio Prates Machado ◽  
Mauricio Zuluaga Martinez
Keyword(s):  
Random Walk ◽  
Random Walks ◽  
Nearest Neighbor ◽  
The Other ◽  
Active Particle ◽  
Positive Probability ◽  
Small Probability ◽  
Active Particles ◽  
Other Hand ◽  
The Right

We consider a random walks system on ℤ in which each active particle performs a nearest-neighbor random walk and activates all inactive particles it encounters. The movement of an active particle stops when it reaches a certain number of jumps without activating any particle. We prove that if the process relies on efficient particles (i.e. those particles with a small probability of jumping to the left) being placed strategically on ℤ, then it might survive, having active particles at any time with positive probability. On the other hand, we may construct a process that dies out eventually almost surely, even if it relies on efficient particles. That is, we discuss what happens if particles are initially placed very far away from each other or if their probability of jumping to the right tends to 1 but not fast enough.

Effect of Third Elements on Pseudoelasticity in Fe3Ga Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 2032-2037 ◽  
Author(s):  
Hiroyuki Y. Yasuda ◽  
Tsuyoshi Furuta ◽  
Takenori Maruyama
Keyword(s):  
Heat Treatment ◽  
Nearest Neighbor ◽  
Antiphase Boundary ◽  
Back Stress ◽  
Strain Recovery ◽  
The Other ◽  
Frictional Stress ◽  
The Third ◽  
Superlattice Structure ◽  
Pseudoelastic Behavior

Pseudoelasticity of Fe3Ga polycrystals doped with third elements (Ti, V, Cr, Mn, Co, Ni, Si, Ge) was examined. Fe3Ga polycrystals with the appropriate heat treatment were found to exhibit large pseudoelasticity based on reversible motion of dislocation dragging an antiphase boundary (APB). In Fe3Ga crystals with the D03 superlattice structure, paired 1/4<111> superpartial dislocations mainly moved dragging the next-nearest-neighbor APB during loading. During unloading, the APB pulled back the superpartial dislocations resulting in the pseudoelasticity. The D03 ordered phase also developed in Fe3Ga polycrystals with 2at% of the third elements. However, the strain recovery of Fe3Ga polycrystals depended strongly on third element. Fe3Ga polycrystals doped with 2at% of Mn, Cr and Co demonstrated large pseudoelasticity. In contrast, the other doped elements decreased the amount of strain recovery. The frictional stress of 1/4<111> superpartial dislocations and the back stress due to the APB, acting on the dislocations, changed by doping the third elements, which was closely related to the pseudoelastic behavior. It is also noted that there was a good correlation between the APB back stress and the ordering temperature from the B2 to D03 phase.

Nearest neighbors and Voronoi regions in certain point processes

1983 ◽  
Vol 15 (4) ◽  
pp. 726-751 ◽  
Author(s):  
C. M. Newman ◽  
Y. Rinott ◽  
A. Tversky
Keyword(s):  
Point Processes ◽  
Random Number ◽  
Nearest Neighbor ◽  
Nearest Neighbors ◽  
Poisson Processes ◽  
The Other ◽  
Other Hand ◽  
Voronoi Regions ◽  
Dimensional Cube

We investigate, for several models of point processes, the (random) number N of points which have a given point as their nearest neighbor. The largedimensional limit of Poisson processes is treated by considering for n points independently and uniformly distributed in a d-dimensional cube of volume n and showing that Poisson (λ= 1). An asymptotic Poisson (λ= 1) distribution also holds for many of the other models. On the other hand, we find that . Related results concern the (random) volume, , of a Voronoi polytope (or Dirichlet cell) in the cube model; we find that while

The Evolution of the {110}<001> and {236}<385> Recrystallization Textures in Cu Alloys and High Mn Austenitic Steels with the Brass Rolling Texture

2016 ◽  
Vol 725 ◽  
pp. 177-182
Author(s):  
Dong Nyung Lee
Keyword(s):  
Recrystallization Texture ◽  
Texture Evolution ◽  
Rolling Texture ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
The Other ◽  
Austenitic Steels ◽  
Stored Energy ◽  
Oriented Growth ◽  
Other Hand

The {110}<112> rolling texture of Cu-22%Zn and Cu-30%Zn sheets having relatively low stacking fault energy transforms into the {236}<385> texture after recrystallization. The 40°<111> relation is approximately satisfied between the {110}<112> and {236}<385> textures. The 40°<111> relation is often addressed as a token of the oriented growth theory for the recrystallization texture evolution. On the other hand, Cu-16%Mn and Cu-1%P alloys and high Mn austenitic steels such as Fe-18%Mn-0.6%C, Fe-18%Mn-1.5%Al-0.6%C, and Fe-18%Mn-3%Al-0.6%C sheets having relatively high stacking fault energy also have the {110}<112> rolling texture, which transforms into the {110}<001> texture after recrystallization. The 40°<111> relation is not established between the {110}<112> rolling texture and the {110}<001> recrystallization texture. The differences are attributed to differences in the stacking fault energies of the materials. The phenomena can be explained by defects that dominates the stored energy of the rolled materials. When the grain boundary energy dominates the stored energy, the {236}<385> texture evolves after recrystallization. On the other hand, when dislocation energy dominates the stored energy, the {110}<001> texture evolves after recrystallization. The {110}<001> recrystallization texture evolution is well explained by the strain-energy-release-maximization theory. The 40°<111> relation is believed to originate in the maximum mobility of <111> tilt boundaries at a rotation angle of 40°.

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