Atomistic, generalized Peierls–Nabarro and analytical models for (111) twist boundaries in Al, Cu and Ni for all twist angles

The hot-pressing technique which has been successfully used to manufacture twist boundaries in silicon has now been used to form tilt boundaries in this material. In the present study, weak-beam imaging, lattice-fringe imaging and electron diffraction techniques have been combined to identify different features of the interface structure. The weak-beam technique gives an overall picture of the geometry of the boundary and in particular allows steps in the plane of the boundary which are normal to the dislocation lines to be identified. It also allows pockets of amorphous SiO2 remaining in the interface to be recognized. The lattice-fringe imaging technique allows the boundary plane parallel to the dislocation to be identified. Finally the electron diffraction technique allows the periodic structure of the boundary to be evaluated over a large area - this is particularly valuable when the dislocations are closely spaced - and can also provide information on the structural width of the interface.

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High-resolution x-ray analysis of dislocation networks nn tilt boundaries

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105126 ◽

1988 ◽

Vol 46 ◽

pp. 612-613

Author(s):

J. R. Michael ◽

C. H. Lin ◽

S. L. Sass

Keyword(s):

Grain Boundaries ◽

Analytical Electron Microscopy ◽

Solute Segregation ◽

X Ray ◽

Periodic Arrays ◽

Analytical Electron ◽

Primary Dislocation ◽

Tilt Boundaries ◽

Polycrystalline Solids ◽

Twist Boundaries

The segregation of solute atoms to grain boundaries in polycrystalline solids can be responsible for embrittlement of the grain boundaries. Although Auger electron spectroscopy (AES) and analytical electron microscopy (AEM) have verified the occurrence of solute segregation to grain boundaries, there has been little experimental evidence concerning the distribution of the solute within the plane of the interface. Sickafus and Sass showed that Au segregation causes a change in the primary dislocation structure of small angle [001] twist boundaries in Fe. The bicrystal specimens used in their work, which contain periodic arrays of dislocations to which Au is segregated, provide an excellent opportunity to study the distribution of Au within the boundary by AEM.The thin film Fe-0.8 at% Au bicrystals (composition determined by Rutherford backscattering spectroscopy), ∼60 nm thick, containing [001] twist boundaries were prepared as described previously. The bicrystals were analyzed in a Vacuum Generators HB-501 AEM with a field emission electron source and a Link Analytical windowless x-ray detector.

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High-resolution microscopy of twin boundaries in gold

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126202 ◽

1987 ◽

Vol 45 ◽

pp. 260-261

Author(s):

William Krakow ◽

David A. Smith

Keyword(s):

High Resolution ◽

Specimen Preparation ◽

Gold Films ◽

Boundary Area ◽

Transmission Electron ◽

Recent Developments ◽

Tilt Boundaries ◽

High Resolution Microscopy ◽

Twist Boundaries

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.

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Mechanism of irregular crack-propagation in thermal controlled fracture of ceramics induced by microwave

Mechanics & Industry ◽

10.1051/meca/2020077 ◽

2020 ◽

Vol 21 (6) ◽

pp. 610

Author(s):

Xiaoliang Cheng ◽

Chunyang Zhao ◽

Hailong Wang ◽

Yang Wang ◽

Zhenlong Wang

Keyword(s):

Crack Propagation ◽

Industrial Application ◽

Ceramic Materials ◽

Advanced Technology ◽

Analytical Models ◽

Propagation Mechanism ◽

Unstable Crack ◽

Fracture Simulation ◽

Initial Stage ◽

Controlled Fracture

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

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Classifying the Past: Discriminant Analysis and its Application to Medieval Farming Systems

History and Computing ◽

10.3366/hac.1996.8.1.1 ◽

1996 ◽

Vol 8 (1) ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Ken Bartley

Keyword(s):

Cluster Analysis ◽

Discriminant Analysis ◽

Processing Time ◽

Farming Systems ◽

Frame Of Reference ◽

Analytical Models ◽

Successful Implementation ◽

Medieval Period ◽

The Past ◽

Livestock Management

This paper discusses the need for nationally based analytical models of the medieval period. The use of cluster analysis as a method for classifying demesne farms, by the crops they grew and their livestock management, is explained. Successful implementation of cluster analysis requires both the existence of a large base sample, to permit isolation of specific groupings within the data, and access to considerable processing time. The paper concludes by demonstrating how discriminant analysis can provide an efficient and systematic way of classifying even a single manor within a national frame of reference.

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Analytical Models for Search of an Object Moving in the Road Network

Telecommunications and Radio Engineering ◽

10.1615/telecomradeng.v64.i2.70 ◽

2005 ◽

Vol 64 (2) ◽

pp. 139-147

Author(s):

D. A. Strebkov ◽

A. S. Sizov

Keyword(s):

Road Network ◽

Analytical Models ◽

The Road

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Validation of a Belt Model for Prediction of Hub Forces from a Rolling Tire4

Tire Science and Technology ◽

10.2346/1.3130984 ◽

2009 ◽

Vol 37 (2) ◽

pp. 62-102 ◽

Cited By ~ 3

Author(s):

C. Lecomte ◽

W. R. Graham ◽

D. J. O’Boy

Keyword(s):

Internal Pressure ◽

Equations Of Motion ◽

Three Dimensional ◽

Prediction Method ◽

Analytical Models ◽

Beam Model ◽

Impedance Boundary ◽

Bending Waves ◽

Tire Rotation ◽

Three Dimensional Models

Abstract An integrated model is under development which will be able to predict the interior noise due to the vibrations of a rolling tire structurally transmitted to the hub of a vehicle. Here, the tire belt model used as part of this prediction method is first briefly presented and discussed, and it is then compared to other models available in the literature. This component will be linked to the tread blocks through normal and tangential forces and to the sidewalls through impedance boundary conditions. The tire belt is modeled as an orthotropic cylindrical ring of negligible thickness with rotational effects, internal pressure, and prestresses included. The associated equations of motion are derived by a variational approach and are investigated for both unforced and forced motions. The model supports extensional and bending waves, which are believed to be the important features to correctly predict the hub forces in the midfrequency (50–500 Hz) range of interest. The predicted waves and forced responses of a benchmark structure are compared to the predictions of several alternative analytical models: two three dimensional models that can support multiple isotropic layers, one of these models include curvature and the other one is flat; a one-dimensional beam model which does not consider axial variations; and several shell models. Finally, the effects of internal pressure, prestress, curvature, and tire rotation on free waves are discussed.

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Investigations of Road Wear Caused by Studded Tires

Tire Science and Technology ◽

10.2346/tire.14.420101 ◽

2014 ◽

Vol 42 (1) ◽

pp. 2-15

Author(s):

Johannes Gültlinger ◽

Frank Gauterin ◽

Christian Brandau ◽

Jan Schlittenhard ◽

Burkhard Wies

Keyword(s):

Traffic Safety ◽

Test Bench ◽

Operating Conditions ◽

Test Method ◽

Analytical Models ◽

The Road ◽

Driving Speed ◽

Major Factors ◽

Tire Friction ◽

Variable Operating Conditions

ABSTRACT The use of studded tires has been a subject of controversy from the time they came into market. While studded tires contribute to traffic safety under severe winter conditions by increasing tire friction on icy roads, they also cause damage to the road surface when running on bare roads. Consequently, one of the main challenges in studded tire development is to reduce road wear while still ensuring a good grip on ice. Therefore, a research project was initiated to gain understanding about the mechanisms and influencing parameters involved in road wear by studded tires. A test method using the institute's internal drum test bench was developed. Furthermore, mechanisms causing road wear by studded tires were derived from basic analytical models. These mechanisms were used to identify the main parameters influencing road wear by studded tires. Using experimental results obtained with the test method developed, the expected influences were verified. Vehicle driving speed and stud mass were found to be major factors influencing road wear. This can be explained by the stud impact as a dominant mechanism. By means of the test method presented, quantified and comparable data for road wear caused by studded tires under controllable conditions can be obtained. The mechanisms allow predicting the influence of tire construction and variable operating conditions on road wear.

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