An optimum design for a time-of-flight neutron diffractometer for measuring engineering stresses

A method is described for optimizing the design of a time-of-flight neutron diffractometer designed to measure lattice parameters. Such diffractometers are now used extensively by engineers and materials scientists for measuring strain within metallic and ceramic components. The method presented relies on the identification of a figure of merit (FOM) that accurately describes the performance of such an instrument. For the first time, an FOM for an instrument exhibiting non-Gaussian peak shapes is described, and the methods by which this FOM may be maximized are described. Although the instrument described is based on the time-of-flight technique, the FOM derived may equally well be used to optimize a reactor-based instrument. While measuring peak position is a straightforward example, it is shown that similar figures of merit may be found for other peak shape parameters, and thus other types of instrumentation.

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Proteins and direct methods

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1524/zkri.1991.197.3-4.197 ◽

1991 ◽

Vol 197 (3-4) ◽

Cited By ~ 7

Author(s):

Fan Hai-fu ◽

Hao Quan ◽

M. M. Woolfson

Keyword(s):

First Principles ◽

Figure Of Merit ◽

Direct Methods ◽

Large Structure ◽

Low Resolution ◽

Figures Of Merit ◽

Large Structures ◽

Resolution Data

AbstractConventional direct methods, which work so well for small structures, are less successful for macromolecules. Where it has been demonstrated that a solution might be found using direct methods it is then found that the usual figures of merit are unable to distinguish the few good sets of phases from the large number of sets generated. The reasons for the difficulties with very large structures are considered from a first-principles approach taking into account both the factors of having a large number of atoms and low resolution data. A proposal is made for trying to recognize good phase sets by taking a large structure as a sum of a number of smaller structures for each of which a conventional figure of merit can be applied.

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Multicanonical Molecular Dynamics Simulation Study of the Liquid-Solid and Solid-Solid Transitions in Lennard-Jones Clusters

ASME/JSME 2011 8th Thermal Engineering Joint Conference ◽

10.1115/ajtec2011-44457 ◽

2011 ◽

Author(s):

Toshihiro Kaneko ◽

Kenji Yasuoka ◽

Ayori Mitsutake ◽

Xiao Cheng Zeng

Keyword(s):

Molecular Dynamics ◽

Heat Capacity ◽

Transition Temperature ◽

Peak Position ◽

Temperature Curve ◽

Dynamics Simulation ◽

Lennard Jones ◽

Dynamics Simulations ◽

First Time ◽

Good Agreement

Multicanonical molecular dynamics simulations are applied, for the first time, to study the liquid-solid and solid-solid transitions in Lennard-Jones (LJ) clusters. The transition temperatures are estimated based on the peak position in the heat capacity versus temperature curve. For LJ31, LJ58 and LJ98, our results on the solid-solid transition temperature are in good agreement with previous ones. For LJ309, the predicted liquid-solid transition temperature is also in agreement with previous result.

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Resolution of time-of-flight small-angle neutron diffractometers

Journal of Applied Crystallography ◽

10.1107/s0021889887086679 ◽

1987 ◽

Vol 20 (4) ◽

pp. 273-279 ◽

Cited By ~ 7

Author(s):

R. P. Hjelm

Keyword(s):

Small Angle ◽

National Laboratory ◽

Argonne National Laboratory ◽

Time Of Flight ◽

Simple Method ◽

Neutron Diffractometer ◽

Reduction Methods ◽

Measurement Strategies ◽

Pulsed Neutron ◽

Pulsed Neutron Source

A simple method of calculating the resolution of small-angle neutron data from diffractometers which use time-of-flight techniques has been derived in terms of the variances of the time and spatial channels of the measurement. The method is used to calculate the resolution in scattering-vector space of scattering intensity from a simulated isotropic scatterer on the small-angle neutron diffractometer at the Intense Pulsed Neutron Source at Argonne National Laboratory. The effects of the various instrumental geometries, time-of-flight measurement strategies and data reduction methods that can be chosen by the experimenter are considered. It is found that the best resolution is obtained with weighted constant Δt/t time-of-flight data acquisition schemes, with the detector placed in the beam in such a way that the highest possible angular range is accessed.

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Analysis on Secondary Effect of Corrugated Webs in Steel-Concrete Composite Beams

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.596 ◽

2011 ◽

Vol 255-260 ◽

pp. 596-601 ◽

Cited By ~ 1

Author(s):

Ke Bin Jiang ◽

Yong Ding ◽

Ya Wen Liu ◽

Feng Zheng

Keyword(s):

Local Buckling ◽

Secondary Effect ◽

Shape Parameters ◽

Corrugated Webs ◽

Analytical Work ◽

Corrugated Web ◽

Finite Element Package ◽

First Time ◽

Numerical And Analytical Methods ◽

Good Agreement

Some secondary effect introduced by corrugated configuration of corrugated web was studied and formulas were proposed. The deduction for these formulas was resolved into two steps. Step I: to solve the behavior of whole corrugated web by considering it as an orthotropic plate; Step II: to solve the secondary effect according to the shape parameters of corrugation based on the result of Step I. Subsequently, a numerical experiment was designed to validate the analytical work with the help of finite element package ANSYS taking material nonlinearity into consideration. The results obtained from numerical and analytical methods show good agreement. It indicates that the formulas proposed in this paper are convenient and efficient. This research deals with this secondary effect for the first time; more studies are needed for the effect on local buckling of corrugated webs.

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Average shape of longitudinal shower profiles measured at the Pierre Auger Observatory

EPJ Web of Conferences ◽

10.1051/epjconf/201921002015 ◽

2019 ◽

Vol 210 ◽

pp. 02015

Author(s):

Sofia Andringa ◽

Keyword(s):

Cosmic Ray ◽

High Energy ◽

Pierre Auger Observatory ◽

Composition Analysis ◽

Shape Parameters ◽

Hadronic Interactions ◽

Shower Development ◽

Shower Maximum ◽

Detailed Composition ◽

First Time

The average profiles of cosmic ray shower development as a function of atmospheric depth are measured for the first time with the Fluorescence Detectors at the Pierre Auger Observatory. The profile shapes are well reproduced by the Gaisser-Hillas parametrization at the 1% level in a 500 g/cm2 interval around the shower maximum, for cosmic rays with log(E/eV) > 17.8. The results are quantified with two shape parameters, measured as a function of energy. The average profiles carry information on the primary cosmic ray and its high energy hadronic interactions. The shape parameters predicted by the commonly used models are compatible with the measured ones within experimental uncertainties. Those uncertainties are dominated by systematics which, at present, prevent a detailed composition analysis.

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Direct analysis of alkaloids in natural Cinchona bark and commercial extracts using time-of-flight secondary ion mass spectrometry

Analytical Methods ◽

10.1039/c7ay02822a ◽

2018 ◽

Vol 10 (9) ◽

pp. 950-958 ◽

Cited By ~ 2

Author(s):

Derick N. Ateacha ◽

Ulrike Koch ◽

Carsten Engelhard

Keyword(s):

Mass Spectrometry ◽

Secondary Ion Mass Spectrometry ◽

Time Of Flight ◽

Direct Analysis ◽

Tof Sims ◽

Ion Mass Spectrometry ◽

First Time ◽

Secondary Ion

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is used for the first time to characterize Cinchona alkaloids in natural Cinchona bark and commercial Cinchona extracts.

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Optimisation of confinement in a fusion reactor using a nonlinear turbulence model

Journal of Plasma Physics ◽

10.1017/s002237781800034x ◽

2018 ◽

Vol 84 (2) ◽

Cited By ~ 7

Author(s):

E. G. Highcock ◽

N. R. Mandell ◽

M. Barnes ◽

W. Dorland

Keyword(s):

First Principles ◽

Figure Of Merit ◽

Large Scale ◽

Unit Volume ◽

Fusion Reactor ◽

Small Scale ◽

Zonal Flows ◽

Novel Approach ◽

First Time ◽

Turbulent Cascade

The confinement of heat in the core of a magnetic fusion reactor is optimised using a multidimensional optimisation algorithm. For the first time in such a study, the loss of heat due to turbulence is modelled at every stage using first-principles nonlinear simulations which accurately capture the turbulent cascade and large-scale zonal flows. The simulations utilise a novel approach, with gyrofluid treatment of the small-scale drift waves and gyrokinetic treatment of the large-scale zonal flows. A simple near-circular equilibrium with standard parameters is chosen as the initial condition. The figure of merit, fusion power per unit volume, is calculated, and then two control parameters, the elongation and triangularity of the outer flux surface, are varied, with the algorithm seeking to optimise the chosen figure of merit. A twofold increase in the plasma power per unit volume is achieved by moving to higher elongation and strongly negative triangularity.

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Reversed de Wolff figure of merit and its application to powder indexing solutions

Journal of Applied Crystallography ◽

10.1107/s0021889813018773 ◽

2013 ◽

Vol 46 (5) ◽

pp. 1277-1282 ◽

Cited By ~ 6

Author(s):

R. Oishi-Tomiyasu

Keyword(s):

Figure Of Merit ◽

Zero Point ◽

Figures Of Merit

Two new figures of merit for powder indexing solutions are proposed: the reversed figure of meritMnRevand the symmetric figure of meritMnSym. These are naturally suggested by the theory underlying the de Wolff figure of meritMn. Nevertheless,MnRevhas characteristics opposite to those ofMnwith regard to sensitivity to impurity peaks and extinct reflections.MnSymhas intermediate properties betweenMnandMnRev. Applications of the new figures of merit to powder indexing solutions and zero-point shift estimation are introduced. All of the figures of merit are available from the powder auto-indexing softwareConograph(http://sourceforge.jp/projects/conograph/; http://research.kek.jp/people/rtomi/ConographGUI/web_page.html).

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A single-crystal time-of-flight neutron diffractometer at a spallation neutron source

Journal of Applied Crystallography ◽

10.1107/s0021889807023059 ◽

2007 ◽

Vol 40 (4) ◽

pp. 799-807 ◽

Cited By ~ 4

Author(s):

Miwako Takahashi ◽

Ken-ichi Ohshima ◽

Masatoshi Arai

Keyword(s):

Phase Transitions ◽

Single Crystal ◽

Neutron Source ◽

Diffuse Scattering ◽

Time Of Flight ◽

Magnetic Scattering ◽

Spallation Neutron Source ◽

Neutron Diffractometer ◽

Incommensurate Structures ◽

Asymmetric Pulse

A single-crystal diffractometer using the time-of-flight (TOF) Laue technique had been operated for studies of structural and magnetic disorder and phase transitions in alloys and magnetic materials at the pulsed spallation neutron source facility of the KEK Neutron Science Laboratory (KENS). In various sample environments, the diffractometer has demonstrated its usefulness in measurements of diffuse scattering for studying local structures, and in surveys of reciprocal space for studying phase transitions and incommensurate structures under the conditions of varying temperature and magnetic field. Particular emphasis is placed on the fact that though the instrument did not receive high-flux neutrons for long wavelengths suitable for the studies of magnetic scattering, it gave good results on the observations of magnetic diffuse scattering and superlattice reflections. Remarks and future tasks of the TOF Laue technique are discussed in relation to the asymmetric pulse shape, separation of the inelastic scattering, and dependence of data correction on the sample quality.

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Non-Gaussian Local Density Diffusion (LDD-) Model for Boron Diffusion in Si- and SixGe1-x Ultra-Shallow Junction Post-Implant and Advanced Rapid-Thermal-Anneals

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.305-306.71 ◽

2010 ◽

Vol 305-306 ◽

pp. 71-84 ◽

Cited By ~ 1

Author(s):

Frank Wirbeleit

Keyword(s):

Silicon Germanium ◽

Local Density ◽

Host Lattice ◽

Boron Diffusion ◽

Lattice Systems ◽

Boron Clusters ◽

Convolution Approach ◽

Non Gaussian ◽

Boron Penetration ◽

First Time

Boron diffusion after implant and anneal has been studied extensively in the past, without de-convoluting the Boron diffusion behavior by the initial post implant Boron concentration profile, which is done in this work first time. To support the de-convolution approach, the local density diffusion (LDD) model is selected, because this model is based on just one single arbitrary diffusion parameter per atomic species and host lattice combination. The LDD model is used for Phosphorus and Arsenic diffusion so far and an extension to simulate Boron diffusion in presence of Boron clusters is presented here. As the result, maximum Boron penetration depth post different rapid thermal anneals and the quantification of diffusing and clustering (non-diffusing) Boron in silicon and silicon-germanium host lattice systems are given.

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