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.

Current-induced reordering phase transitions of vortex matter in 3D-layered superconductors

2018 ◽  
Vol 32 (25) ◽  
pp. 1850281 ◽  
Author(s):  
Qingmiao Nie ◽  
Haibin Li
Keyword(s):  
Phase Transitions ◽  
Thermal Noise ◽  
Vortex Lattice ◽  
Three Dimensional ◽  
Xy Model ◽  
Vortex Matter ◽  
Nonequilibrium Phase Transitions ◽  
External Current ◽  
Layered Superconductors ◽  
Pinning Potential

Nonequilibrium phase transitions of vortex matter with a strong random pinning potential in layered superconductors are investigated by the three-dimensional frustrated anisotropic XY model and resistively-shunted junction dynamics at low, middle and high-temperatures, respectively. It is found that a disorder to order phase transition driven by an external current can be obtained at a low-temperature, however, a reordering configuration does not occur at a high-temperature. With the competition between thermal noise, disorder pins and current, the vortex matter can even show the reordering process twice at an intermediate temperature, giving a clear evidence of dc driven vortex lattice reorganization.

Vortices in superconducting nano-networks with anti-dots array

Open Physics ◽  
2012 ◽  
Vol 10 (3) ◽  
Author(s):  
Kazuto Hirata ◽  
Ajay Thakur ◽  
Shuuichi Ooi ◽  
Takashi Mochiku
Keyword(s):  
Vortex Flow ◽  
Vortex Lattice ◽  
Abrikosov Vortex ◽  
Melting Transition ◽  
Solid State Physics ◽  
Matching Effect ◽  
Atomic Lattice ◽  
First Order ◽  
Vortex Physics ◽  
Magneto Resistance

AbstractVortices (magnetic flux quanta) in the superconducting networks perforated with anti-dots (holes) arrays behave as electrons in atomic lattice of crystals. Repulsive and attractive interaction among vortices and anti-dots resemble to those among electrons and atoms in crystals. To confirm the variety of the vortex physics similar to the solid state physics, we have fabricated such superconducting networks with antidots array in metallic, inter-metallic and high-T c superconductors (HTSCs), and have measured magneto-resistance of vortex-flow. In these materials, we have observed integer-matching at the matching fields and fractional-matching effect between them. Most of them are well explained by commensurability between Abrikosov vortex lattice and anti-dots array. Furthermore, the effect of the anti-dots array in HTSCs appears as another kind of phase transitions instead of to the first-order melting transition of vortex lattice in pristine samples.

Neutron diffraction measurements of residual stress and plastic deformation in an aluminium alloy weld

1988 ◽  
Vol 23 (4) ◽  
pp. 201-211 ◽  
Author(s):  
D J Smith ◽  
R H Leggatt ◽  
G A Webster ◽  
H J Macgillivray ◽  
P J Webster ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Plastic Strain ◽  
Residual Stresses ◽  
Aluminium Alloy ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Accurate Indication ◽  
Neutron Diffraction Technique ◽  
Neutron Diffraction Method ◽  
Alloy Weld

The neutron diffraction technique for measuring residual stresses non-destructively in an aluminium alloy weld has been examined. Calibration experiments have been performed to determine the influence of prior plastic strain and surface effects. Comparisons have also been made with strain gauge methods using the destructive block removal and layering technique for measuring the residual stresses. It has been shown that the neutron diffraction method gives an accurate indication of the three dimensional stress distribution present in a weld and that it can also be employed to estimate the amount of prior plastic strain encountered.

scholarly journals Rapid imaging of special nuclear materials for nuclear nonproliferation and terrorism prevention

2021 ◽  
Vol 7 (21) ◽  
pp. eabg3032
Author(s):  
Jana Petrović ◽  
Alf Göök ◽  
Bo Cederwall
Keyword(s):  
Nuclear Physics ◽  
Imaging Modality ◽  
Three Dimensional ◽  
Nuclear Fission ◽  
Machine Learning Techniques ◽  
Nuclear Materials ◽  
Prototype System ◽  
Fast Time ◽  
Gamma Emission ◽  
Special Nuclear Materials

We introduce a neutron-gamma emission tomography (NGET) technique for rapid detection, three-dimensional imaging, and characterization of special nuclear materials like weapons-grade plutonium and uranium. The technique is adapted from fundamental nuclear physics research and represents a previously unexplored approach to the detection and imaging of small quantities of these materials. The method is demonstrated on a radiation portal monitor prototype system based on fast organic scintillators, measuring the characteristic fast time and energy correlations between particles emitted in nuclear fission processes. The use of these correlations in real time in conjunction with modern machine learning techniques provides unprecedented imaging efficiency and high spatial resolution. This imaging modality addresses global security threats from terrorism and the proliferation of nuclear weapons. It also provides enhanced capabilities for addressing different nuclear accident scenarios and for environmental radiological surveying.

scholarly journals PhytoSFDM version 1.0.0: Phytoplankton Size and Functional Diversity Model

2016 ◽  
Vol 9 (11) ◽  
pp. 4071-4085 ◽  
Author(s):  
Esteban Acevedo-Trejos ◽  
Gunnar Brandt ◽  
S. Lan Smith ◽  
Agostino Merico
Keyword(s):  
Open Source ◽  
Open Source Software ◽  
Marine Ecosystem ◽  
Three Dimensional ◽  
Functional Trait ◽  
Global Ocean ◽  
Total Biomass ◽  
Spatially Resolved ◽  
Phytoplankton Communities ◽  
Natural Complexity

Abstract. Biodiversity is one of the key mechanisms that facilitate the adaptive response of planktonic communities to a fluctuating environment. How to allow for such a flexible response in marine ecosystem models is, however, not entirely clear. One particular way is to resolve the natural complexity of phytoplankton communities by explicitly incorporating a large number of species or plankton functional types. Alternatively, models of aggregate community properties focus on macroecological quantities such as total biomass, mean trait, and trait variance (or functional trait diversity), thus reducing the observed natural complexity to a few mathematical expressions. We developed the PhytoSFDM modelling tool, which can resolve species discretely and can capture aggregate community properties. The tool also provides a set of methods for treating diversity under realistic oceanographic settings. This model is coded in Python and is distributed as open-source software. PhytoSFDM is implemented in a zero-dimensional physical scheme and can be applied to any location of the global ocean. We show that aggregate community models reduce computational complexity while preserving relevant macroecological features of phytoplankton communities. Compared to species-explicit models, aggregate models are more manageable in terms of number of equations and have faster computational times. Further developments of this tool should address the caveats associated with the assumptions of aggregate community models and about implementations into spatially resolved physical settings (one-dimensional and three-dimensional). With PhytoSFDM we embrace the idea of promoting open-source software and encourage scientists to build on this modelling tool to further improve our understanding of the role that biodiversity plays in shaping marine ecosystems.

A Time-Domain Fluid-Structure Interaction Analysis of Fan Blades

2008 ◽  
Author(s):  
Seung Ho Cho ◽  
Taehyoun Kim ◽  
Seung Jin Song
Keyword(s):  
Time Domain ◽  
Vortex Lattice ◽  
Interaction Analysis ◽  
Three Dimensional ◽  
Incoming Flow ◽  
Structure Interaction ◽  
Unsteady Aerodynamic ◽  
Aerodynamic Model ◽  
Blade Row ◽  
Fan Blade

This paper presents aerodynamic and aeromechanical analyses for an entire row of fan blades (i.e. tens of blades with a finite aspect ratio) subject to a uniform incoming flow. In this regard, a new unsteady three-dimensional vortex lattice model has been developed for multiple blades in discrete time domain. Using the new model, the characteristics of the unsteady aerodynamic forces on vibrating blades, including their temporal development, are examined. Also, the new aerodynamic model is applied to examine the aeromechanical behavior of fan blades by using a standard eigenvalue analysis. For this analysis, the fan blades have been modeled as three-dimensional plates, and, increasing the number of blades (or solidity) is predicted to destabilize the fan blade row.

Growth Evolution of (Zn,Cd)Se Quantum Dots Deduced from Spatially Resolved Structural and Optical Characterization

1999 ◽  
Vol 571 ◽  
Author(s):  
K. Leonard ◽  
D. Hommel ◽  
A. Stockmann ◽  
H. Selke ◽  
J. Seufert ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Wells ◽  
Three Dimensional ◽  
High Energy ◽  
Growth Direction ◽  
Growth Mode ◽  
Gradual Transition ◽  
Mode Transition ◽  
Spatially Resolved ◽  
Composition Fluctuations

ABSTRACTThe growth mode of CdSe layers grown by migration enhanced epitaxy between ZnSe barriers has been investigated. In situ reflection high-energy electron diffraction shows a gradual transition to a three-dimensional growth mode which, however, is not accompanied by a change of the surface lattice constant. High-resolution transmission electron micrographs reveal a strong Cd diffusion, leading to ternary ZnCdSe quantum wells. Furthermore. composition fluctuations perpendicular to the growth direction on a nanometer scale are found already prior to the beginning of the growth mode transition. In the case of heterostructures containing a CdSe layer that has undergone the growth mode transition, micrographs show Cd-rich quantum dots with diameters of around 8 nm and heights of around 1.5 nm within a ternary quantum well. By spatially resolved photoluminescence the emission from single quantum dots could be observed. The polarization dependence of the emission from single dots indicates an asymmetric shape of the dots with certain preferential orientations along the [110] and [110] directions.

scholarly journals Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Alberto Cereser ◽  
Markus Strobl ◽  
Stephen A. Hall ◽  
Axel Steuwer ◽  
Ryoji Kiyanagi ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Three Dimensional ◽  
Time Of Flight ◽  
Transmission Mode ◽  
Grain Structures

A Framework for Designing Component Shapes in a Virtual Reality Environment

1997 ◽  
Author(s):  
Tushar H. Dani ◽  
Rajit Gadh
Keyword(s):  
Virtual Reality ◽  
Virtual Environment ◽  
User Interfaces ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Human Interaction ◽  
Prototype System ◽  
Virtual Design ◽  
Cad System ◽  
Interactive Editing

Abstract Despite advances in Computer-Aided Design (CAD) and the evolution of the graphical user interfaces, rapid creation, editing and visualization of three-dimensional (3D) shapes remains a tedious task. Though the availability of Virtual Reality (VR)-based systems allows enhanced three-dimensional interaction and visualization, the use of VR for ab initio shape design, as opposed to ‘importing’ models from existing CAD systems, is a relatively new area of research. Of interest are computer-human interaction issues and the design and geometric tools for shape modeling in a Virtual Environment (VE). The focus of this paper is on the latter i.e. in defining the geometric tools required for a VR-CAD system and in describing a framework that meets those requirements. This framework, the Virtual Design Software Framework (VDSF) consists of the interaction and design tools, and an underlying geometric engine that provides the representation and algorithms required by these tools. The geometric engine called the Virtual Modeler uses a graph-based representation (Shape-Graph) for modeling the shapes created by the user. The Shape-Graph facilitates interactive editing by localizing the effect of editing operations and in addition provides constraint-based design and editing mechanisms that are useful in a 3D interactive virtual environment. The paper concludes with a description of the prototype system, called the Virtual Design Studio (VDS), that is currently being implemented.1.

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