550 V, N-channel emitter switched thyristors with an atomic-lattice-layout (ALL) geometry

1994 ◽  
Vol 15 (11) ◽  
pp. 452-454 ◽  
Author(s):  
A. Bhalla ◽  
T.P. Chow
Keyword(s):  
Atomic Lattice

scholarly journals Internal stress created by plastic flow in mild steel, and stress-strain curves for the atomic lattice of higher carbon steels

1944 ◽  
Vol 182 (991) ◽  
pp. 404-414 ◽  
Keyword(s):  
Mild Steel ◽  
Internal Stress ◽  
Plastic Flow ◽  
Carbon Steels ◽  
External Stress ◽  
Stress Strain ◽  
Atomic Lattice ◽  
X Ray ◽  
Elastic Range ◽  
Residual Strains

In previous work, stress-strain curves for the atomic lattice of certain metals have been obtained from X-ray diffraction measurements of the lattice dimensions of test specimens under tension or compression, and it has been shown that when the external yield stress is exceeded, there is a systematic departure from Hooke’s Law. It is pointed out in the present paper that this departure indicates that the external applied stress above the yield is no longer balanced primarily by simple displacement of the atoms but also by a new type of secondary internal stress brought about by the process of plastic flow; and that this secondary stress, being of a permanent nature, can be measured by the residual lattice strains exhibited by the lattice after removal of the external stress. These residual strains are measured in various directions to the stress direction for mild steel subjected to tension, and it is shown that the lattice after tension exhibits a longitudinal compression and a transverse expansion in the ratio of 2:1, which means that the density of the material is thereby kept constant. Comparisons of X-ray and mechanical measurements further show that the hysteresis loop exhibited by the external stress-strain curve of mild steel after overstrain can disappear and the linear elastic relation be recovered without any corresponding change in the internal stress, which is therefore a more fundamental physical property. It is also shown that when the elastic range is extended by overstrain in tension, there is no symmetrical increase in the elastic range in subsequent compression, thus confirming the existence and direction of the secondary internal stress. Finally, the lattice stress-strain curves are also obtained for a 0.4 % C steel (partially pearlitic) and a 0.8 % C steel (pearlitic), and by comparison with the results on pure iron and 0.1 % C steel (annealed) it is shown that the maximum residual internal strain developed by the lattice increases markedly with the fineness to which the crystallites can be broken down by the plastic deformation.

Tunable optical vortex array in a two-dimensional electromagnetically induced atomic lattice

2021 ◽  
Author(s):  
jinpeng Yuan ◽  
Hengfei ZHANG ◽  
Chaohua Wu ◽  
lirong wang ◽  
liantuan xiao ◽  
...  
Keyword(s):  
Optical Vortex ◽  
Two Dimensional ◽  
Atomic Lattice ◽  
Vortex Array

scholarly journals LOCAL DERIVATIONS ON ALGEBRAS OF MEASURABLE OPERATORS

2011 ◽  
Vol 13 (04) ◽  
pp. 643-657 ◽  
Author(s):  
S. ALBEVERIO ◽  
SH. A. AYUPOV ◽  
K. K. KUDAYBERGENOV ◽  
B. O. NURJANOV
Keyword(s):  
Von Neumann Algebra ◽  
Von Neumann Algebras ◽  
Sufficient Conditions ◽  
Continuity Condition ◽  
Type I ◽  
Atomic Lattice ◽  
Von Neumann ◽  
Measurable Operators ◽  
Finite Trace ◽  
Necessary And Sufficient

The paper is devoted to local derivations on the algebra [Formula: see text] of τ-measurable operators affiliated with a von Neumann algebra [Formula: see text] and a faithful normal semi-finite trace τ. We prove that every local derivation on [Formula: see text] which is continuous in the measure topology, is in fact a derivation. In the particular case of type I von Neumann algebras, they all are inner derivations. It is proved that for type I finite von Neumann algebras without an abelian direct summand, and also for von Neumann algebras with the atomic lattice of projections, the continuity condition on local derivations in the above results is redundant. Finally we give necessary and sufficient conditions on a commutative von Neumann algebra [Formula: see text] for the algebra [Formula: see text] to admit local derivations which are not derivations.

Three-dimensional spatially resolved neutron diffraction from a disordered vortex lattice

2011 ◽  
Vol 44 (2) ◽  
pp. 414-417
Author(s):  
Xi Wang ◽  
Helen A. Hanson ◽  
Xinsheng Sean Ling ◽  
Charles F. Majkrzak ◽  
Brian B. Maranville
Keyword(s):  
Neutron Diffraction ◽  
Vortex Lattice ◽  
Three Dimensional ◽  
Vortex State ◽  
Prototype System ◽  
Vortex Matter ◽  
Atomic Lattice ◽  
Spatially Resolved ◽  
Neutron Diffraction Technique ◽  
Vortex Physics

The vortex matter in bulk type II superconductors serves as a prototype system for studying the random pinning problem in condensed matter physics. Since the vortex lattice is embedded in an atomic lattice, small-angle neutron scattering (SANS) is the only technique that allows for direct structural studies. In traditional SANS methods, the scattering intensity is a measure of the structure factor averaged over the entire sample. Recent studies in vortex physics have shown that it is highly desirable to develop a SANS technique that is capable of resolving the spatial inhomogeneities in the bulk vortex state. This article reports a novel slicing neutron diffraction technique using atypical collimation and an areal detector, which allows for observing the three-dimensional disorder of the vortex matter inside an as-grown Nb single crystal.

Statistical Mechanics: Undamaged ⇐-radiation-⇒ Damaged Atomic Lattice Density Evolution and Stochastic Deformation Functional

2005 ◽  
Vol 887 ◽  
Author(s):  
Ray B. Stout ◽  
Natasha K. Stout
Keyword(s):  
Probability Density ◽  
Radiation Damage ◽  
Probability Density Functions ◽  
Relative Deformation ◽  
Density Functions ◽  
Length Scale ◽  
Atomic Lattice ◽  
Damage Response ◽  
Deformation Kinematics ◽  
Lattice Density

AbstractThe deformation kinematics for radiation damage response of bulk materials is presently semi-empirical and phenomenological based on a continuum mechanics supposition: there exists a function space of continuous functions to describe material displacement, strain, strain-rate metrics by using the mathematics of differential calculus. Existing data being assembled from tests on nano-length-scale(NLS) samples provide objective evidence that the continuum mechanics supposition is not an adequate generic mathematical description for radiation damage response in surface-dominated material structures at NLS. An alternative approach will be described that uses concepts and methods from classical statistical mechanics and describe deformation kinematics as a stochastic accumulation of discrete damage events at atomic lattice nano-length-scales. Although radiation damage deformation at a lattice length-scale in solids is mechanistically different from velocity scattering developed by Boltzmann for a kinetic theory of gases, the two problem areas are technically similar and in some simply cases there are useful mathematical analogs. The technical similarities and mathematical analogs will be used to define probability density functions (number per unit volume functions) for undamaged and damaged “size and size change” lattice species (similarity to a probability density function for atomic velocities in gas theory). In general, equations for undamaged and damaged lattice density function evolution are Boltzmann-type equations, which can be approximated and solved for simple cases of radiation induced material damage. Using a path integral approach and the two probability density functions, a stochastic functional will be derived for the relative deformation between any two arbitrary spatial points in a radiation damaged material. Given the relative deformation as an explicit functional of the undamaged and damaged lattice density functions, the kinematics metrics of relative velocity, strain, strain rate, etc., will also be functionals. In the case of radiation damage and annealing, the two lattice density functions are analog expressions to those commonly used to model “birth and death” population evolution.

Full-Field Deformation and Thermal Characterization of GNP/Epoxy and GNP/SMA Fiber/Epoxy Composites

2019 ◽  
Author(s):  
Ugur Kilic ◽  
Muhammad M. Sherif ◽  
Sherif M. Daghash ◽  
Osman E. Ozbulut
Keyword(s):  
Shape Memory ◽  
Epoxy Matrix ◽  
Large Scale ◽  
Low Cost ◽  
Image Correlation ◽  
Epoxy Composites ◽  
Uniaxial Tensile ◽  
Graphene Sheets ◽  
Atomic Lattice ◽  
Full Field

Abstract Shape memory alloys (SMAs) are a class of metallic alloys that possess remarkable characteristics such as superelasticity and shape memory effect. Superelastic SMAs have been considered as fiber in polymer composites due to their ability to recover their deformation upon removal of load, good energy dissipation capacity and impact resistance. Graphene nanoplatelets (GNPs) consists of small stacks of graphene sheets that are two-dimensional. Both sides of atomic lattice of GNPs contact matrix of a composite system and can generate more sites for potential chemical and physical bonding with the host material. Most importantly, graphene sheets and their derivatives can be produced at large-scale for industrial demand at low-cost. This study explores the fabrication of multi-scale reinforced epoxy matrix composites in which GNPs and SMA strands are employed as nano- and micro-scale reinforcements, respectively. First, GNPs are dispersed into a ductile and brittle epoxy matrix to produce GNP/epoxy nanocomposites. To study the effect of GNP content on the behavior of the developed nanocomposite, GNPs are added to the epoxy-hardener mixture at different weight percentages (neat, 0.1%, 0.25%, 0.5%, 1%, and 2%). Uniaxial tensile tests of the developed nanocomposites are conducted under monotonic load up to failure. The optimum GNP content for GNP-reinforced epoxy matrix is determined and used in the fabrication of SMA fiber/epoxy composite. The developed multiscale reinforced epoxy composites are tested under tensile loading and their full-field strain and temperature behavior are monitored and evaluated using a digital image correlation system and an infrared thermal camera.

scholarly journals Size-dependent diffusion controls natural aging in aluminium alloys

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Phillip Dumitraschkewitz ◽  
Peter J. Uggowitzer ◽  
Stephan S. A. Gerstl ◽  
Jörg F. Löffler ◽  
Stefan Pogatscher
Keyword(s):  
Structural Changes ◽  
Materials Science ◽  
Natural Aging ◽  
Atom Probe ◽  
Rapid Quenching ◽  
Image Resolution ◽  
Atomic Lattice ◽  
Atomic Image ◽  
Microscopy Techniques ◽  
Non Equilibrium

Abstract A key question in materials science is how fast properties evolve, which relates to the kinetics of phase transformations. In metals, kinetics is primarily connected to diffusion, which for substitutional elements is enabled via mobile atomic-lattice vacancies. In fact, non-equilibrium vacancies are often required for structural changes. Rapid quenching of various important alloys, such as Al- or Mg-alloys, results for example in natural aging, i.e. slight movements of solute atoms in the material, which significantly alter the material properties. In this study we demonstrate a size effect of natural aging in an AlMgSi alloy via atom probe tomography with near-atomic image resolution. We show that non-equilibrium vacancy diffusional processes are generally stopped when the sample size reaches the nanometer scale. This precludes clustering and natural aging in samples below a certain size and has implications towards the study of non-equilibrium diffusion and microstructural changes via microscopy techniques.

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