3D shape measurements with a single interferometric sensor for in-situ lathe monitoring

NASA Astrophysics Data System (ADS)

Kuschmierz, R.; Huang, Y.; Czarske, J.; Metschke, S.; Löffler, F.; Fischer, A.

2015-05-01

Temperature drifts, tool deterioration, unknown vibrations as well as spindle play are major effects which decrease the achievable precision of computerized numerically controlled (CNC) lathes and lead to shape deviations between the processed work pieces. Since currently no measurement system exist for fast, precise and in-situ 3d shape monitoring with keyhole access, much effort has to be made to simulate and compensate these effects. Therefore we introduce an optical interferometric sensor for absolute 3d shape measurements, which was integrated into a working lathe. According to the spindle rotational speed, a measurement rate of 2,500 Hz was achieved. In-situ absolute shape, surface profile and vibration measurements are presented. While thermal drifts of the sensor led to errors of several mµm for the absolute shape, reference measurements with a coordinate machine show, that the surface profile could be measured with an uncertainty below one micron. Additionally, the spindle play of 0.8 µm was measured with the sensor.

Adaptive electron beam shaping using a photoemission gun and spatial light modulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.

The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam imagemore » to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.« less

Adaptive electron beam shaping using a photoemission gun and spatial light modulator

NASA Astrophysics Data System (ADS)

Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.; Kiefer, Jacob; Bazarov, Ivan

2015-02-01

The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

Adaptive electron beam shaping using a photoemission gun and spatial light modulator

DOE PAGES

Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.; ...

2015-02-01

The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam imagemore » to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.« less

Modelling of the reactive sputtering process with non-uniform discharge current density and different temperature conditions

NASA Astrophysics Data System (ADS)

Vašina, P; Hytková, T; Eliáš, M

2009-05-01

The majority of current models of the reactive magnetron sputtering assume a uniform shape of the discharge current density and the same temperature near the target and the substrate. However, in the real experimental set-up, the presence of the magnetic field causes high density plasma to form in front of the cathode in the shape of a toroid. Consequently, the discharge current density is laterally non-uniform. In addition to this, the heating of the background gas by sputtered particles, which is usually referred to as the gas rarefaction, plays an important role. This paper presents an extended model of the reactive magnetron sputtering that assumes the non-uniform discharge current density and which accommodates the gas rarefaction effect. It is devoted mainly to the study of the behaviour of the reactive sputtering rather that to the prediction of the coating properties. Outputs of this model are compared with those that assume uniform discharge current density and uniform temperature profile in the deposition chamber. Particular attention is paid to the modelling of the radial variation of the target composition near transitions from the metallic to the compound mode and vice versa. A study of the target utilization in the metallic and compound mode is performed for two different discharge current density profiles corresponding to typical two pole and multipole magnetics available on the market now. Different shapes of the discharge current density were tested. Finally, hysteresis curves are plotted for various temperature conditions in the reactor.

A real-time beam-profile monitor for a PET cyclotron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoehr, C.; Uittenbosch, T.; Verzilov, V.

2012-12-19

Beam profiles in medical cyclotrons are traditionally measured using techniques that do not provide any information about short-term fluctuations of the beam shape or beam intensity. To overcome this, we have developed a real-time harp beam profile monitor which can withstand beam power in excess of 300 W. The monitor and electronics were constructed and applied toward a 13 MeV proton beam with current of up to 25 {mu}A. Herein are reported preliminary beam-profile measurement results.

A real-time beam-profile monitor for a PET cyclotron

NASA Astrophysics Data System (ADS)

Hoehr, C.; Uittenbosch, T.; Verzilov, V.; English, W.; Buckley, K.; Gray, D.; Kellog, S.; Cameron, D.; Schaffer, P.

2012-12-01

Beam profiles in medical cyclotrons are traditionally measured using techniques that do not provide any information about short-term fluctuations of the beam shape or beam intensity. To overcome this, we have developed a real-time harp beam profile monitor which can withstand beam power in excess of 300 W. The monitor and electronics were constructed and applied toward a 13 MeV proton beam with current of up to 25 μA. Herein are reported preliminary beam-profile measurement results.

Observations of pockmark flow structure in Belfast Bay, Maine, Part 1: current-induced mixing

USGS Publications Warehouse

Fandel, Christina L.; Lippmann, Thomas C.; Irish, James D.; Brothers, Laura L.

2017-01-01

Field observations of current profiles and temperature, salinity, and density structure were used to examine vertical mixing within two pockmarks in Belfast Bay, Maine. The first is located in 21 m water depth (sea level to rim), nearly circular in shape with a 45 m rim diameter and 12 m rim-to-bottom relief. The second is located in 25 m water depth, more elongated in shape with an approximately 80 m (36 m) major (minor) axis length at the rim, and 17 m relief. Hourly averaged current profiles were acquired from bottom-mounted acoustic Doppler current profilers deployed on the rim and center of each pockmark over successive 42 h periods in July 2011. Conductivity–temperature–depth casts at the rim and center of each pockmark show warmer, fresher water in the upper water column, evidence of both active and fossil thermocline structure 5–8 m above the rim, and well-mixed water below the rim to the bottom. Vertical velocities show up- and down-welling events that extend into the depths of each pockmark. An observed temperature change at both the rim and center occurs coincident with an overturning event below the rim, and suggests active mixing of the water column into the depths of each pockmark. Vertical profiles of horizontal velocities show depth variation at both the center and rim consistent with turbulent logarithmic current boundary layers, and suggest that form drag may possibly be influencing the local flow regime. While resource limitations prevented observation of the current structure and water properties at a control site, the acquired data suggest that active mixing and overturning within the sampled pockmarks occur under typical benign conditions, and that current flows are influenced by upstream bathymetric irregularities induced by distant pockmarks.

Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

DOE PAGES

Lemery, F.; Piot, P.

2015-08-03

Collinear high-gradient O(GV/m) beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios >2, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting “drive” bunch to an accelerated “witness” bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative continuously differentiable (smooth) current profiles whichmore » support enhanced transformer ratios. We especially demonstrate that one of the devised shapes can be implemented in a photo-emission electron source by properly shaping the photocathode-laser pulse. We finally discuss a possible superconducting linear-accelerator concept that could produce shaped drive bunches at high-repetition rates to drive a dielectric-wakefield accelerator with accelerating fields on the order of ~60 MV/m and a transformer ratio ~5 consistent with a recently proposed multiuser free-electron laser facility.« less

Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemery, F.; Piot, P.

Collinear high-gradient O(GV/m) beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios >2, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting “drive” bunch to an accelerated “witness” bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative continuously differentiable (smooth) current profiles whichmore » support enhanced transformer ratios. We especially demonstrate that one of the devised shapes can be implemented in a photo-emission electron source by properly shaping the photocathode-laser pulse. We finally discuss a possible superconducting linear-accelerator concept that could produce shaped drive bunches at high-repetition rates to drive a dielectric-wakefield accelerator with accelerating fields on the order of ~60 MV/m and a transformer ratio ~5 consistent with a recently proposed multiuser free-electron laser facility.« less

Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

NASA Astrophysics Data System (ADS)

d'Almeida, T.; Lassalle, F.; Morell, A.; Grunenwald, J.; Zucchini, F.; Loyen, A.; Maysonnave, T.; Chuvatin, A. S.

2013-09-01

SPHINX is a 6 MA, 1-μs Linear Transformer Driver (LTD) operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being evaluated to improve the generator performances are an upgrade to a 20 MA, 1-μs LTD machine and various power amplification schemes, including a compact Dynamic Load Current Multiplier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse in order to obtain the desired load current profile. In this paper, we discuss the overall configuration that was selected for these experiments, including the choice of a coaxial cylindrical geometry for the load and its return current electrode. We present both 3-D Magneto-hydrodynamic and 1D Lagrangian hydrodynamic simulations which helped guide the design of the experimental configuration. Initial results obtained over a set of experiments on an aluminium cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented and analyzed. Details of the electrical and laser Doppler interferometer setups used to monitor and diagnose the ramp compression experiments are provided. In particular, the configuration used to field both homodyne and heterodyne velocimetry diagnostics in the reduced access available within the liner's interior is described. Current profiles measured at various critical locations across the system, particularly the load current, enabled a comprehensive tracking of the current circulation and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements obtained from the heterodyne velocimeter agree with the hydrocode results obtained using the measured load current as the input. An extensive hydrodynamic analysis is carried out to examine information such as pressure and particle velocity history profiles or magnetic diffusion across the liner. The potential of the technique in terms of applications and achievable ramp pressure levels lies in the prospects for improving the DLCM efficiency through the use of a closing switch (currently under development), reducing the load dimensions and optimizing the diagnostics.

Minimum magnetic curvature for resilient divertors using Compact Toroidal Hybrid geometry

NASA Astrophysics Data System (ADS)

Bader, A.; Hegna, C. C.; Cianciosa, M.; Hartwell, G. J.

2018-05-01

The properties of resilient divertors are explored using equilibria derived from Compact Toroidal Hybrid (CTH) geometries. Resilience is defined here as the robustness of the strike point patterns as the plasma geometry and/or plasma profiles are changed. The addition of plasma current in the CTH configurations significantly alters the shape of the last closed flux surface and the rotational transform profile, however, it does not alter the strike point pattern on the target plates, and hence has resilient divertor features. The limits of when a configuration transforms to a resilient configuration is then explored. New CTH-like configurations are generated that vary from a perfectly circular cross section to configurations with increasing amounts of toroidal shaping. It is found that even small amounts of toroidal shaping lead to strike point localization that is similar to the standard CTH configuration. These results show that only a small degree of three-dimensional shaping is necessary to produce a resilient divertor, implying that any highly shaped optimized stellarator will possess the resilient divertor property.

Asymmetric simple exclusion process with position-dependent hopping rates: Phase diagram from boundary-layer analysis.

PubMed

Mukherji, Sutapa

2018-03-01

In this paper, we study a one-dimensional totally asymmetric simple exclusion process with position-dependent hopping rates. Under open boundary conditions, this system exhibits boundary-induced phase transitions in the steady state. Similarly to totally asymmetric simple exclusion processes with uniform hopping, the phase diagram consists of low-density, high-density, and maximal-current phases. In various phases, the shape of the average particle density profile across the lattice including its boundary-layer parts changes significantly. Using the tools of boundary-layer analysis, we obtain explicit solutions for the density profile in different phases. A detailed analysis of these solutions under different boundary conditions helps us obtain the equations for various phase boundaries. Next, we show how the shape of the entire density profile including the location of the boundary layers can be predicted from the fixed points of the differential equation describing the boundary layers. We discuss this in detail through several examples of density profiles in various phases. The maximal-current phase appears to be an especially interesting phase where the boundary layer flows to a bifurcation point on the fixed-point diagram.

Asymmetric simple exclusion process with position-dependent hopping rates: Phase diagram from boundary-layer analysis

NASA Astrophysics Data System (ADS)

Mukherji, Sutapa

2018-03-01

In this paper, we study a one-dimensional totally asymmetric simple exclusion process with position-dependent hopping rates. Under open boundary conditions, this system exhibits boundary-induced phase transitions in the steady state. Similarly to totally asymmetric simple exclusion processes with uniform hopping, the phase diagram consists of low-density, high-density, and maximal-current phases. In various phases, the shape of the average particle density profile across the lattice including its boundary-layer parts changes significantly. Using the tools of boundary-layer analysis, we obtain explicit solutions for the density profile in different phases. A detailed analysis of these solutions under different boundary conditions helps us obtain the equations for various phase boundaries. Next, we show how the shape of the entire density profile including the location of the boundary layers can be predicted from the fixed points of the differential equation describing the boundary layers. We discuss this in detail through several examples of density profiles in various phases. The maximal-current phase appears to be an especially interesting phase where the boundary layer flows to a bifurcation point on the fixed-point diagram.

Frequency-agile, rapid scanning cavity ring-down spectroscopy (FARS-CRDS) measurements of the (30012)←(00001) near-infrared carbon dioxide band

NASA Astrophysics Data System (ADS)

Long, D. A.; Wójtewicz, S.; Miller, C. E.; Hodges, J. T.

2015-08-01

We present new high accuracy measurements of the (30012)←(00001) CO2 band near 1575 nm recorded with a frequency-agile, rapid scanning cavity ring-down spectrometer. The resulting spectra were fit with the partially correlated, quadratic-speed-dependent Nelkin-Ghatak profile with line mixing. Significant differences were observed between the fitted line shape parameters and those found in existing databases, which are based upon more simplistic line profiles. Absolute transition frequencies, which were referenced to an optical frequency comb, are given, as well as the other line shape parameters needed to model this line profile. These high accuracy measurements should allow for improved atmospheric retrievals of greenhouse gas concentrations by current and future remote sensing missions.

Generalization of Solovev’s approach to finding equilibrium solutions for axisymmetric plasmas with flow

NASA Astrophysics Data System (ADS)

M, S. CHU; Yemin, HU; Wenfeng, GUO

2018-03-01

Solovev’s approach of finding equilibrium solutions was found to be extremely useful for generating a library of linear-superposable equilibria for the purpose of shaping studies. This set of solutions was subsequently expanded to include the vacuum solutions of Zheng, Wootton and Solano, resulting in a set of functions {SOLOVEV_ZWS} that were usually used for all toroidally symmetric plasmas, commonly recognized as being able to accommodate any desired plasma shapes (complete-shaping capability). The possibility of extending the Solovev approach to toroidal equilibria with a general plasma flow is examined theoretically. We found that the only meaningful extension is to plasmas with a pure toroidal rotation and with a constant Mach number. We also show that the simplification ansatz made to the current profiles, which was the basis of the Solovev approach, should be applied more systematically to include an internal boundary condition at the magnetic axis; resulting in a modified and more useful set {SOLOVEV_ZWSm}. Explicit expressions of functions in this set are given for equilibria with a quasi-constant current density profile, with a toroidal flow at a constant Mach number and with specific heat capacity 1. The properties of {SOLOVEV_ZWSm} are studied analytically. Numerical examples of achievable equilibria are demonstrated. Although the shaping capability of the set {SOLOVE_ZWSm} is quite extensive, it nevertheless still does not have complete shaping capability, particularly for plasmas with negative curvature points on the plasma boundary such as the doublets or indented bean shaped tokamaks.

A real-time intercepting beam-profile monitor for a medical cyclotron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendriks, C.; Uittenbosch, T.; Cameron, D.

2013-11-15

There is a lack of real-time continuous beam-diagnostic tools for medical cyclotrons due to high power deposition during proton irradiation. To overcome this limitation, we have developed a profile monitor that is capable of providing continuous feedback about beam shape and current in real time while it is inserted in the beam path. This enables users to optimize the beam profile and observe fluctuations in the beam over time with periodic insertion of the monitor.

Electrochemical and mechanical polishing and shaping method and system

NASA Technical Reports Server (NTRS)

Engelhaupt, Darell E. (Inventor); Gubarev, Mikhail V. (Inventor); Jones, William David (Inventor); Ramsey, Brian D. (Inventor); Benson, Carl M. (Inventor)

2011-01-01

A method and system are provided for the shaping and polishing of the surface of a material selected from the group consisting of electrically semi-conductive materials and conductive materials. An electrically non-conductive polishing lap incorporates a conductive electrode such that, when the polishing lap is placed on the material's surface, the electrode is placed in spaced-apart juxtaposition with respect to the material's surface. A liquid electrolyte is disposed between the material's surface and the electrode. The electrolyte has an electrochemical stability constant such that cathodic material deposition on the electrode is not supported when a current flows through the electrode, the electrolyte and the material. As the polishing lap and the material surface experience relative movement, current flows through the electrode based on (i) adherence to Faraday's Law, and (ii) a pre-processing profile of the surface and a desired post-processing profile of the surface.

Generation of Ramped Current Profiles in Relativistic Electron Beams Using Wakefields in Dielectric Structures

DOE PAGES

Andonian, G.; Barber, S.; O’Shea, F. H.; ...

2017-02-03

We show that temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs a beam wakefield interaction in a dielectric structure, followed by bunch compression in a permanent magnet chicane, to longitudinally tailor the pulse shape of an electron beam. This compact, passive, approach was used to generate a nearly linearly ramped current profile in a relativistic electron beam experiment carried out at the Brookhaven National Laboratory Accelerator Test Facility. Here, we report on these experimental results including beam and wakefieldmore » diagnostics and pulse profile reconstruction techniques.« less

The ion temperature gradient: An intrinsic property of Earth's magnetotail

NASA Astrophysics Data System (ADS)

Lu, San; Artemyev, A. V.; Angelopoulos, V.; Lin, Y.; Wang, X. Y.

2017-08-01

Although the ion temperature gradient along (XGSM) and across (ZGSM) the Earth's magnetotail, which plays a key role in generating the cross-tail current and establishing pressure balance with the lobes, has been extensively observed by spacecraft, the mechanism responsible for its formation is still unknown. We use multispacecraft observations and three-dimensional (3-D) global hybrid simulations to reveal this mechanism. Using THEMIS (Time History of Events and Macroscale Interactions during Substorms), Geotail, and ARTEMIS (Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun) observations during individual, near-simultaneous plasma sheet crossings from 10 to 60 RE, we demonstrate that the ion temperature ZGSM profile is bell-shaped at different geocentric distances. This ZGSM profile is also prevalent in statistics of 200 THEMIS current sheet crossings in the near-Earth region. Using 3-D global hybrid simulations, we show that mapping of the XGSM gradient of ion temperature along magnetic field lines produces such a bell-shaped profile. The ion temperature mapping along magnetic field lines in the magnetotail enables construction of two-dimensional distributions of these quantities from vertical (north-south) spacecraft crossings. Our findings suggest that the ion temperature gradient is an intrinsic property of the magnetotail that should be considered in kinetic descriptions of the magnetotail current sheet. Toward this goal, we use theoretical approaches to incorporate the temperature gradient into kinetic current sheet models, making them more realistic.

Optimization of Kink Stability in High-Beta Quasi-axisymmetric Stellarators

NASA Astrophysics Data System (ADS)

Fu, G. Y.; Ku, L.-P.; Manickam, J.; Cooper, W. A.

1998-11-01

A key issue for design of Quasi-axisymmetric stellarators( A. Reiman et al, this conference.) (QAS) is the stability of external kink modes driven by pressure-induced bootstrap current. In this work, the 3D MHD stability code TERPSICHORE(W.A. Cooper, Phys. Plasmas 3), 275(1996). is used to calculate the stability of low-n external kink modes in a high-beta QAS. The kink stability is optimized by adjusting plasma boundary shape (i.e., external coil configuration) as well as plasma pressure and current profiles. For this purpose, the TERPSICHORE code has been implemented successfully in an optimizer which maximizes kink stability as well as quasi-symmetry. A key factor for kink stability is rotational transform profile. It is found that the edge magnetic shear is strongly stabilizing. The amount of the shear needed for complete stabilization increases with edge transform. It is also found that the plasma boundary shape plays an important role in the kink stability besides transform profile. The physics mechanisms for the kink stability are being studied by examining the contributions of individual terms in δ W of the energy principle: the field line bending term, the current-driven term, the pressure-driven term, and the vacuum term. Detailed results will be reported.

Minimum magnetic curvature for resilient divertors using Compact Toroidal Hybrid geometry

DOE PAGES

Bader, Aaron; Hegna, C. C.; Cianciosa, Mark R.; ...

2018-03-16

The properties of resilient divertors are explored using equilibria derived from Compact Toroidal Hybrid (CTH) geometries. Resilience is defined here as the robustness of the strike point patterns as the plasma geometry and/or plasma profiles are changed. The addition of plasma current in the CTH configurations significantly alters the shape of the last closed flux surface and the rotational transform profile, however, it does not alter the strike point pattern on the target plates, and hence has resilient divertor features. The limits of when a configuration transforms to a resilient configuration is then explored. New CTH-like configurations are generated thatmore » vary from a perfectly circular cross section to configurations with increasing amounts of toroidal shaping. It is found that even small amounts of toroidal shaping lead to strike point localization that is similar to the standard CTH configuration. Lastly, these results show that only a small degree of three-dimensional shaping is necessary to produce a resilient divertor, implying that any highly shaped optimized stellarator will possess the resilient divertor property.« less

Radio-frequency current drive efficiency in the presence of ITBs and a dc electric field

NASA Astrophysics Data System (ADS)

Rosa, P. R. da S.; Mourão, R.; Ziebell, L. F.

2009-05-01

This paper discusses the current drive efficiency by the combined action of EC and LH waves in the presence of a dc electric field and transport, with an internal transport barrier. The transport is assumed to be produced by magnetic fluctuations. The study explores the different barrier parameters and their influence on the current drive efficiency. We study the subject by numerically solving the Fokker-Planck equation. Our main result is that the barrier depth and barrier width are important to determine the correct shape of the current density profile but not to determine the current drive efficiency, which is very little influenced by these parameters. We also found similar results for the influence of the level of magnetic fluctuations on the current density profile and on the current drive efficiency.

Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Almeida, T.; Lassalle, F.; Morell, A.

SPHINX is a 6 MA, 1-μs Linear Transformer Driver (LTD) operated by the CEA Gramat (France) and primarily used for imploding Z-pinch loads for radiation effects studies. Among the options that are currently being evaluated to improve the generator performances are an upgrade to a 20 MA, 1-μs LTD machine and various power amplification schemes, including a compact Dynamic Load Current Multiplier (DLCM). A method for performing magnetic ramp compression experiments, without modifying the generator operation scheme, was developed using the DLCM to shape the initial current pulse in order to obtain the desired load current profile. In this paper,more » we discuss the overall configuration that was selected for these experiments, including the choice of a coaxial cylindrical geometry for the load and its return current electrode. We present both 3-D Magneto-hydrodynamic and 1D Lagrangian hydrodynamic simulations which helped guide the design of the experimental configuration. Initial results obtained over a set of experiments on an aluminium cylindrical liner, ramp-compressed to a peak pressure of 23 GPa, are presented and analyzed. Details of the electrical and laser Doppler interferometer setups used to monitor and diagnose the ramp compression experiments are provided. In particular, the configuration used to field both homodyne and heterodyne velocimetry diagnostics in the reduced access available within the liner's interior is described. Current profiles measured at various critical locations across the system, particularly the load current, enabled a comprehensive tracking of the current circulation and demonstrate adequate pulse shaping by the DLCM. The liner inner free surface velocity measurements obtained from the heterodyne velocimeter agree with the hydrocode results obtained using the measured load current as the input. An extensive hydrodynamic analysis is carried out to examine information such as pressure and particle velocity history profiles or magnetic diffusion across the liner. The potential of the technique in terms of applications and achievable ramp pressure levels lies in the prospects for improving the DLCM efficiency through the use of a closing switch (currently under development), reducing the load dimensions and optimizing the diagnostics.« less

Determination of current and rotational transform profiles in a current-carrying stellarator using soft x-ray emissivity measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, X.; Cianciosa, M. R.; Ennis, D. A.

In this research, collimated soft X-ray (SXR) emissivity measurements from multi-channel cameras on the Compact Toroidal Hybrid (CTH) tokamak/torsatron device are incorporated in the 3D equilibrium reconstruction code V3FIT to reconstruct the shape of flux surfaces and infer the current distribution within the plasma. Equilibrium reconstructions of sawtoothing plasmas that use data from both SXR and external magnetic diagnostics show the central safety factor to be near unity under the assumption that SXR iso-emissivity contours lie on magnetic flux surfaces. The reconstruction results are consistent with those using the external magnetic data and a constraint on the location of qmore » = 1 surfaces determined from the sawtooth inversion surface extracted from SXR brightness profiles. The agreement justifies the use of approximating SXR emission as a flux function in CTH, at least within the core of the plasma, subject to the spatial resolution of the SXR diagnostics. Lastly, this improved reconstruction of the central current density indicates that the current profile peakedness decreases with increasing external transform and that the internal inductance is not a relevant measure of how peaked the current profile is in hybrid discharges.« less

Determination of current and rotational transform profiles in a current-carrying stellarator using soft x-ray emissivity measurements

NASA Astrophysics Data System (ADS)

Ma, X.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Herfindal, J. L.; Howell, E. C.; Knowlton, S. F.; Maurer, D. A.; Traverso, P. J.

2018-01-01

Collimated soft X-ray (SXR) emissivity measurements from multi-channel cameras on the Compact Toroidal Hybrid (CTH) tokamak/torsatron device are incorporated in the 3D equilibrium reconstruction code V3FIT to reconstruct the shape of flux surfaces and infer the current distribution within the plasma. Equilibrium reconstructions of sawtoothing plasmas that use data from both SXR and external magnetic diagnostics show the central safety factor to be near unity under the assumption that SXR iso-emissivity contours lie on magnetic flux surfaces. The reconstruction results are consistent with those using the external magnetic data and a constraint on the location of q = 1 surfaces determined from the sawtooth inversion surface extracted from SXR brightness profiles. The agreement justifies the use of approximating SXR emission as a flux function in CTH, at least within the core of the plasma, subject to the spatial resolution of the SXR diagnostics. This improved reconstruction of the central current density indicates that the current profile peakedness decreases with increasing external transform and that the internal inductance is not a relevant measure of how peaked the current profile is in hybrid discharges.

Determination of current and rotational transform profiles in a current-carrying stellarator using soft x-ray emissivity measurements

DOE PAGES

Ma, X.; Cianciosa, M. R.; Ennis, D. A.; ...

2018-01-31

In this research, collimated soft X-ray (SXR) emissivity measurements from multi-channel cameras on the Compact Toroidal Hybrid (CTH) tokamak/torsatron device are incorporated in the 3D equilibrium reconstruction code V3FIT to reconstruct the shape of flux surfaces and infer the current distribution within the plasma. Equilibrium reconstructions of sawtoothing plasmas that use data from both SXR and external magnetic diagnostics show the central safety factor to be near unity under the assumption that SXR iso-emissivity contours lie on magnetic flux surfaces. The reconstruction results are consistent with those using the external magnetic data and a constraint on the location of qmore » = 1 surfaces determined from the sawtooth inversion surface extracted from SXR brightness profiles. The agreement justifies the use of approximating SXR emission as a flux function in CTH, at least within the core of the plasma, subject to the spatial resolution of the SXR diagnostics. Lastly, this improved reconstruction of the central current density indicates that the current profile peakedness decreases with increasing external transform and that the internal inductance is not a relevant measure of how peaked the current profile is in hybrid discharges.« less

Spatio-temporal shaping of photocathode laser pulses for linear electron accelerators

NASA Astrophysics Data System (ADS)

Mironov, S. Yu; Andrianov, A. V.; Gacheva, E. I.; Zelenogorskii, V. V.; Potemkin, A. K.; Khazanov, E. A.; Boonpornprasert, P.; Gross, M.; Good, J.; Isaev, I.; Kalantaryan, D.; Kozak, T.; Krasilnikov, M.; Qian, H.; Li, X.; Lishilin, O.; Melkumyan, D.; Oppelt, A.; Renier, Y.; Rublack, T.; Felber, M.; Huck, H.; Chen, Y.; Stephan, F.

2017-10-01

Methods for the spatio-temporal shaping of photocathode laser pulses for generating high brightness electron beams in modern linear accelerators are discussed. The possibility of forming triangular laser pulses and quasi-ellipsoidal structures is analyzed. The proposed setup for generating shaped laser pulses was realised at the Institute of Applied Physics (IAP) of the Russian Academy of Sciences (RAS). Currently, a prototype of the pulse-shaping laser system is installed at the Photo Injector Test facility at DESY, Zeuthen site (PITZ). Preliminary experiments on electron beam generation using ultraviolet laser pulses from this system were carried out at PITZ, in which electron bunches with a 0.5-nC charge and a transverse normalized emittance of 1.1 mm mrad were obtained. A new scheme for the three-dimensional shaping of laser beams using a volume Bragg profiled grating is proposed at IAP RAS and is currently being tested for further electron beam generation experiments at the PITZ photoinjector.

Determination of optimum fin profile for a zero-G capillary drained condenser

NASA Technical Reports Server (NTRS)

Mccormick, John A.; Valenzuela, Javier A.; Choudhury, Dipanker

1990-01-01

This paper presents the analytical formulation and numerical results for heat transfer in a high heat flux condenser that relies on capillary flow along shaped fins (Gregorig surfaces) and a drainage network embedded in the condenser walls. Results are shown for a variety of fin profile shapes in order to show the geometric trade-offs involved in seeking a maximum effective heat transfer coefficient for the fin. Predictions of the model show excellent agreement with previously reported measurements for steam. Based on this work, a profile has been selected for a 2 kW ammonia condenser currently under development for use in space. In that design the fin half width is 0.5 mm and the model predicts a heat transfer coefficient referred to the base of the fin of 9 W/sq cm deg C for a heat flux of 10/W sq cm at the base.

RMP ELM Suppression in DIII-D Plasmas with ITER Similar Shapes and Collisionalities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, T.E.; Fenstermacher, M. E.; Moyer, R.A.

2008-01-01

Large Type-I edge localized modes (ELMs) are completely eliminated with small n = 3 resonant magnetic perturbations (RMP) in low average triangularity, = 0.26, plasmas and in ITER similar shaped (ISS) plasmas, = 0.53, with ITER relevant collisionalities ve 0.2. Significant differences in the RMP requirements and in the properties of the ELM suppressed plasmas are found when comparing the two triangularities. In ISS plasmas, the current required to suppress ELMs is approximately 25% higher than in low average triangularity plasmas. It is also found that the width of the resonant q95 window required for ELM suppression is smaller inmore » ISS plasmas than in low average triangularity plasmas. An analysis of the positions and widths of resonant magnetic islands across the pedestal region, in the absence of resonant field screening or a self-consistent plasma response, indicates that differences in the shape of the q profile may explain the need for higher RMP coil currents during ELM suppression in ISS plasmas. Changes in the pedestal profiles are compared for each plasma shape as well as with changes in the injected neutral beam power and the RMP amplitude. Implications of these results are discussed in terms of requirements for optimal ELM control coil designs and for establishing the physics basis needed in order to scale this approach to future burning plasma devices such as ITER.« less

Design and simulation of control algorithms for stored energy and plasma current in non-inductive scenarios on NSTX-U

NASA Astrophysics Data System (ADS)

Boyer, Mark; Andre, Robert; Gates, David; Gerhardt, Stefan; Menard, Jonathan; Poli, Francesca

2015-11-01

One of the major goals of NSTX-U is to demonstrate non-inductive operation. To facilitate this and other program goals, the center stack has been upgraded and a second neutral beam line has been added with three sources aimed more tangentially to provide higher current drive efficiency and the ability to shape the current drive profile. While non-inductive start-up and ramp-up scenarios are being developed, initial non-inductive studies will likely rely on clamping the Ohmic coil current after the plasma current has been established inductively. In this work the ability to maintain control of stored energy and plasma current once the Ohmic coil has been clamped is explored. The six neutral beam sources and the mid-plane outer gap of the plasma are considered as actuators. System identification is done using TRANSP simulations in which the actuators are modulated around a reference shot. The resulting reduced model is used to design an optimal control law with anti-windup and a recently developed framework for closed loop simulations in TRANSP is used to test the control. Limitations due to actuator saturation are assessed and robustness to beam modulation, changes in the plasma density and confinement, and changes in density and temperature profile shapes are studied. Supported by US DOE contract DE-AC02-09CH11466.

High performance mode locking characteristics of single section quantum dash lasers.

PubMed

Rosales, Ricardo; Murdoch, S G; Watts, R T; Merghem, K; Martinez, Anthony; Lelarge, Francois; Accard, Alain; Barry, L P; Ramdane, Abderrahim

2012-04-09

Mode locking features of single section quantum dash based lasers are investigated. Particular interest is given to the static spectral phase profile determining the shape of the mode locked pulses. The phase profile dependence on cavity length and injection current is experimentally evaluated, demonstrating the possibility of efficiently using the wide spectral bandwidth exhibited by these quantum dash structures for the generation of high peak power sub-picosecond pulses with low radio frequency linewidths.

Design of Launch Abort System Thrust Profile and Concept of Operations

NASA Technical Reports Server (NTRS)

Litton, Daniel; O'Keefe, Stephen A.; Winski, Richard G.; Davidson, John B.

2008-01-01

This paper describes how the Abort Motor thrust profile has been tailored and how optimizing the Concept of Operations on the Launch Abort System (LAS) of the Orion Crew Exploration Vehicle (CEV) aides in getting the crew safely away from a failed Crew Launch Vehicle (CLV). Unlike the passive nature of the Apollo system, the Orion Launch Abort Vehicle will be actively controlled, giving the program a more robust abort system with a higher probability of crew survival for an abort at all points throughout the CLV trajectory. By optimizing the concept of operations and thrust profile the Orion program will be able to take full advantage of the active Orion LAS. Discussion will involve an overview of the development of the abort motor thrust profile and the current abort concept of operations as well as their effects on the performance of LAS aborts. Pad Abort (for performance) and Maximum Drag (for separation from the Launch Vehicle) are the two points that dictate the required thrust and shape of the thrust profile. The results in this paper show that 95% success of all performance requirements is not currently met for Pad Abort. Future improvements to the current parachute sequence and other potential changes will mitigate the current problems, and meet abort performance requirements.

Non-axisymmetric equilibrium reconstruction and suppression of density limit disruptions in a current-carrying stellarator

NASA Astrophysics Data System (ADS)

Ma, Xinxing; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Knowlton, S. F.; Maurer, D. A.

2017-10-01

Non-axisymmetric equilibrium reconstructions have been routinely performed with the V3FIT code in the Compact Toroidal Hybrid (CTH), a stellarator/tokamak hybrid. In addition to 50 external magnetic measurements, 160 SXR emissivity measurements are incorporated into V3FIT to reconstruct the magnetic flux surface geometry and infer the current distribution within the plasma. Improved reconstructions of current and q profiles provide insight into understanding the physics of density limit disruptions observed in current-carrying discharges in CTH. It is confirmed that the final scenario of the density limit of CTH plasmas is consistent with classic observations in tokamaks: current profile shrinkage leads to growing MHD instabilities (tearing modes) followed by a loss of MHD equilibrium. It is also observed that the density limit at a given current linearly increases with increasing amounts of 3D shaping fields. Consequently, plasmas with densities up to two times the Greenwald limit are attained. Equilibrium reconstructions show that addition of 3D fields effectively moves resonance surfaces towards the edge of the plasma where the current profile gradient is less, providing a stabilizing effect. This work is supported by US Department of Energy Grant No. DE-FG02-00ER54610.

Non-axisymmetric equilibrium reconstruction of a current-carrying stellarator using external magnetic and soft x-ray inversion radius measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, X., E-mail: xzm0005@auburn.edu; Maurer, D. A.; Knowlton, S. F.

2015-12-15

Non-axisymmetric free-boundary equilibrium reconstructions of stellarator plasmas are performed for discharges in which the magnetic configuration is strongly modified by ohmically driven plasma current. These studies were performed on the compact toroidal hybrid device using the V3FIT reconstruction code with a set of 50 magnetic diagnostics external to the plasma. With the assumption of closed magnetic flux surfaces, the reconstructions using external magnetic measurements allow accurate estimates of the net toroidal flux within the last closed flux surface, the edge safety factor, and the plasma shape of these highly non-axisymmetric plasmas. The inversion radius of standard sawteeth is used tomore » infer the current profile near the magnetic axis; with external magnetic diagnostics alone, the current density profile is imprecisely reconstructed.« less

Non-axisymmetric equilibrium reconstruction of a current-carrying stellarator using external magnetic and soft x-ray inversion radius measurements

NASA Astrophysics Data System (ADS)

Ma, X.; Maurer, D. A.; Knowlton, S. F.; ArchMiller, M. C.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Hebert, J. D.; Herfindal, J. L.; Pandya, M. D.; Roberds, N. A.; Traverso, P. J.

2015-12-01

Non-axisymmetric free-boundary equilibrium reconstructions of stellarator plasmas are performed for discharges in which the magnetic configuration is strongly modified by ohmically driven plasma current. These studies were performed on the compact toroidal hybrid device using the V3FIT reconstruction code with a set of 50 magnetic diagnostics external to the plasma. With the assumption of closed magnetic flux surfaces, the reconstructions using external magnetic measurements allow accurate estimates of the net toroidal flux within the last closed flux surface, the edge safety factor, and the plasma shape of these highly non-axisymmetric plasmas. The inversion radius of standard sawteeth is used to infer the current profile near the magnetic axis; with external magnetic diagnostics alone, the current density profile is imprecisely reconstructed.

Non-axisymmetric equilibrium reconstruction of a current-carrying stellarator using external magnetic and soft x-ray inversion radius measurements

DOE PAGES

Ma, X.; Maurer, D. A.; Knowlton, Stephen F.; ...

2015-12-22

Non-axisymmetric free-boundary equilibrium reconstructions of stellarator plasmas are performed for discharges in which the magnetic configuration is strongly modified by ohmically driven plasma current. These studies were performed on the compact toroidal hybrid device using the V3FIT reconstruction code with a set of 50 magnetic diagnostics external to the plasma. With the assumption of closed magnetic flux surfaces, the reconstructions using external magnetic measurements allow accurate estimates of the net toroidal flux within the last closed flux surface, the edge safety factor, and the plasma shape of these highly non-axisymmetric plasmas. Lastly, the inversion radius of standard saw-teeth is usedmore » to infer the current profile near the magnetic axis; with external magnetic diagnostics alone, the current density profile is imprecisely reconstructed.« less

Resistive instabilities in tokamaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rutherford, P.H.

1985-10-01

Low-m tearing modes constitute the dominant instability problem in present-day tokamaks. In this lecture, the stability criteria for representative current profiles with q(0)-values slightly less than unit are reviewed; ''sawtooth'' reconnection to q(0)-values just at, or slightly exceeding, unity is generally destabilizing to the m = 2, n = 1 and m = 3, n = 2 modes, and severely limits the range of stable profile shapes. Feedback stabilization of m greater than or equal to 2 modes by rf heating or current drive, applied locally at the magnetic islands, appears feasible; feedback by island current drive is much moremore » efficient, in terms of the radio-frequency power required, then feedback by island heating. Feedback stabilization of the m = 1 mode - although yielding particularly beneficial effects for resistive-tearing and high-beta stability by allowing q(0)-values substantially below unity - is more problematical, unless the m = 1 ideal-MHD mode can be made positively stable by strong triangular shaping of the central flux surfaces. Feedback techniques require a detectable, rotating MHD-like signal; the slowing of mode rotation - or the excitation of non-rotating modes - by an imperfectly conducting wall is also discussed.« less

Analysis of asymmetric property with DC bias current on thin-film magnetoimpedance element

NASA Astrophysics Data System (ADS)

Kikuchi, Hiroaki; Sumida, Chihiro

2018-05-01

We theoretically analyzed the magnetoimpedance profile of a thin-film element with a DC bias current using the bias susceptibility theory and Maxwell's equations. Although the analysis model predicts that an element with a rectangular cross section shows symmetric impedance property with respect to the Z-axis with DC bias current, the experimental results showed asymmetric properties. Taking the shape imbalance and trapezoidal cross section of the element into account, we explained the asymmetric impedance properties qualitatively.

Beam shaping to improve the free-electron laser performance at the Linac Coherent Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Y.; Bane, K. L. F.; Colocho, W.

2016-10-27

A new operating mode has been developed for the Linac Coherent Light Source (LCLS) in which we shape the longitudinal phase space of the electron beam. This mode of operation is realized using a horizontal collimator located in the middle of the first bunch compressor to truncate the head and tail of the beam. With this method, the electron beam longitudinal phase space and current profile are reshaped, and improvement in lasing performance can be realized. As a result, we present experimental studies at the LCLS of the beam shaping effects on the free-electron laser performance.

Mathematical investigations of branch length similarity entropy profiles of shapes for various resolutions

NASA Astrophysics Data System (ADS)

Jeon, Wonju; Lee, Sang-Hee

2012-12-01

In our previous study, we defined the branch length similarity (BLS) entropy for a simple network consisting of a single node and numerous branches. As the first application of this entropy to characterize shapes, the BLS entropy profiles of 20 battle tank shapes were calculated from simple networks created by connecting pixels in the boundary of the shape. The profiles successfully characterized the tank shapes through a comparison of their BLS entropy profiles. Following the application, this entropy was used to characterize human's emotional faces, such as happiness and sad, and to measure the degree of complexity for termite tunnel networks. These applications indirectly indicate that the BLS entropy profile can be a useful tool to characterize networks and shapes. However, the ability of the BLS entropy in the characterization depends on the image resolution because the entropy is determined by the number of nodes for the boundary of a shape. Higher resolution means more nodes. If the entropy is to be widely used in the scientific community, the effect of the resolution on the entropy profile should be understood. In the present study, we mathematically investigated the BLS entropy profile of a shape with infinite resolution and numerically investigated the variation in the pattern of the entropy profile caused by changes in the resolution change in the case of finite resolution.

Variability of O3 and NO2 profile shapes during DISCOVER-AQ: Implications for satellite observations and comparisons to model-simulated profiles

NASA Astrophysics Data System (ADS)

Flynn, Clare Marie; Pickering, Kenneth E.; Crawford, James H.; Weinheimer, Andrew J.; Diskin, Glenn; Thornhill, K. Lee; Loughner, Christopher; Lee, Pius; Strode, Sarah A.

2016-12-01

To investigate the variability of in situ profile shapes under a variety of meteorological and pollution conditions, results are presented of an agglomerative hierarchical cluster analysis of the in situ O3 and NO2 profiles for each of the four campaigns of the NASA DISCOVER-AQ mission. Understanding the observed profile variability for these trace gases is useful for understanding the accuracy of the assumed profile shapes used in satellite retrieval algorithms as well as for understanding the correlation between satellite column observations and surface concentrations. The four campaigns of the DISCOVER-AQ mission took place in Maryland during July 2011, the San Joaquin Valley of California during January-February 2013, the Houston, Texas, metropolitan region during September 2013, and the Denver-Front Range region of Colorado during July-August 2014. Several distinct profile clusters emerged for the California, Texas, and Colorado campaigns for O3, indicating significant variability of O3 profile shapes, while the Maryland campaign presented only one distinct O3 cluster. In contrast, very few distinct profile clusters emerged for NO2 during any campaign for this particular clustering technique, indicating the NO2 profile behavior was relatively uniform throughout each campaign. However, changes in NO2 profile shape were evident as the boundary layer evolved through the day, but they were apparently not significant enough to yield more clusters. The degree of vertical mixing (as indicated by temperature lapse rate) associated with each cluster exerted an important influence on the shapes of the median cluster profiles for O3, as well as impacted the correlations between the associated column and surface data for each cluster for O3. The correlation analyses suggest satellites may have the best chance to relate to surface O3 under the conditions encountered during the Maryland campaign Clusters 1 and 2, which include deep, convective boundary layers and few interruptions to this connection from complex meteorology, chemical environments, or orography. The regional CMAQ model captured the shape factors for O3, and moderately well captured the NO2 shape factors, for the conditions associated with the Maryland campaign, suggesting that a regional air quality model may adequately specify a priori profile shapes for remote sensing retrievals. CMAQ shape factor profiles were not as well represented for the other regions.

Brain strain uncertainty due to shape variation in and simplification of head angular velocity profiles.

PubMed

Zhao, Wei; Ji, Songbai

2017-04-01

Head angular velocity, instead of acceleration, is more predictive of brain strains. Surprisingly, no study exists that investigates how shape variation in angular velocity profiles affects brain strains, beyond characteristics such as peak magnitude and impulse duration. In this study, we evaluated brain strain uncertainty due to variation in angular velocity profiles and further compared with that resulting from simplifying the profiles into idealized shapes. To do so, we used reconstructed head impacts from American National Football League for shape extraction and simulated head uniaxial coronal rotations from onset to full stop. The velocity profiles were scaled to maintain an identical peak velocity magnitude and duration in order to isolate the shape for investigation. Element-wise peak maximum principal strains from 44 selected impacts were obtained. We found that the shape of angular velocity profile could significantly affect brain strain magnitude (e.g., percentage difference of 4.29-17.89 % in the whole brain relative to the group average, with cumulative strain damage measure (CSDM) uncertainty range of 23.9 %) but not pattern (correlation coefficient of 0.94-0.99). Strain differences resulting from simplifying angular velocity profiles into idealized shapes were largely within the range due to shape variation, in both percentage difference and CSDM (signed difference of 3.91 % on average, with a typical range of 0-6 %). These findings provide important insight into the uncertainty or confidence in the performance of kinematics-based injury metrics. More importantly, they suggest the feasibility to simplify head angular velocity profiles into idealized shapes, at least within the confinements of the profiles evaluated, to enable real-time strain estimation via pre-computation in the future.

Brain strain uncertainty due to shape variation in and simplification of head angular velocity profiles

PubMed Central

Zhao, Wei; Ji, Songbai

2016-01-01

Head angular velocity, instead of acceleration, is more predictive of brain strains. Surprisingly, no study exists that investigates how shape variation in angular velocity profiles affects brain strains, beyond characteristics such as peak magnitude and impulse duration. In this study, we evaluated brain strain uncertainty due to variation in angular velocity profiles, and further compared with that resulting from simplifying the profiles into idealized shapes. To do so, we used reconstructed head impacts from American National Football League for shape extraction, and simulated head uniaxial coronal rotations from onset to full stop. The velocity profiles were scaled to maintain an identical peak velocity magnitude and duration in order to isolate the shape for investigation. Element-wise peak maximum principal strains from 44 selected impacts were obtained. We found that the shape of angular velocity profile could significantly affect brain strain magnitude (e.g., percentage difference of 4.29–17.89% in the whole-brain relative to the group average, with cumulative strain damage measure (CSDM) uncertainty range of 23.9%) but not pattern (correlation coefficient of 0.94–0.99). Strain differences resulting from simplifying angular velocity profiles into idealized shapes were largely within the range due to shape variation, in both percentage difference and CSDM (signed difference of 3.91% on average, with a typical range of 0–6%). These findings provide important insight into the uncertainty or confidence in the performance of kinematics-based injury metrics. More importantly, they suggest the feasibility to simplify head angular velocity profiles into idealized shapes, at least within the confinements of the profiles evaluated, to enable real-time strain estimation via pre-computation in the future. PMID:27644441

Relating shape/weight based self-esteem, depression, and anxiety with weight and perceived physical health among young adults.

PubMed

Kamody, Rebecca C; Thurston, Idia B; Decker, Kristina M; Kaufman, Caroline C; Sonneville, Kendrin R; Richmond, Tracy K

2018-06-01

Simultaneous contributions of self-esteem, depression, and anxiety to weight and perceived physical health in young adults is understudied. A diverse sample of 424 young adults completed measures of shape/weight based self-esteem, depression, anxiety, and perceived physical health. Height and weight were measured to calculate body mass index (BMI). Latent profile analysis was conducted to derive patterns of depression, anxiety, and shape/weight based self-esteem. Then, we examined the association of the profiles with weight status and perceived physical health. Three profiles emerged: (1) High Shape/Weight Influence (HSWI); (2) Low Shape/Weight, Depression, & Anxiety Influence (LSWDAI); and (3) High Depression & Anxiety Influence (HDAI). The HSWI profile had significantly higher BMI than the LSWDAI and HDAI profiles, and significantly lower perceived physical health than the LSWDAI profile. Over emphasis on shape/weight, regardless of depression and anxiety, is associated with elevated weight and negative internalized health views. Copyright © 2018 Elsevier Ltd. All rights reserved.

Application specific beam profiles: new surface and thin-film refinement processes using beam shaping technologies

NASA Astrophysics Data System (ADS)

Hauschild, Dirk

2017-02-01

Today, the use of laser photons for materials processing is a key technology in nearly all industries. Most of the applications use circular beam shapes with Gaussian intensity distribution that is given by the resonator of the laser or by the power delivery via optical fibre. These beam shapes can be typically used for material removal with cutting or drilling and for selective removal of material layers with ablation processes. In addition to the removal of materials, it is possible to modify and improve the material properties in case the dose of laser photons and the resulting light-material interaction addresses a defined window of energy and dwell-time. These process windows have typically dwell-times between µs and s because of using sintering, melting, thermal diffusion or photon induced chemical and physical reaction mechanisms. Using beam shaping technologies the laser beam profiles can be adapted to the material properties and time-temperature and the space-temperature envelopes can be modified to enable selective annealing or crystallization of layers or surfaces. Especially the control of the process energy inside the beam and at its edges opens a large area of laser applications that can be addressed only with an optimized spatial and angular beam profile with down to sub-percent intensity variation used in e.g. immersion lithography tools with ArF laser sources. LIMO will present examples for new beam shapes and related material refinement processes even on large surfaces and give an overview about new mechanisms in laser material processing for current and coming industrial applications.

The Development of Spontaneous Sound-Shape Matching in Monolingual and Bilingual Infants during the First Year

ERIC Educational Resources Information Center

Pejovic, Jovana; Molnar, Monika

2017-01-01

Recently it has been proposed that sensitivity to nonarbitrary relationships between speech sounds and objects potentially bootstraps lexical acquisition. However, it is currently unclear whether preverbal infants (e.g., before 6 months of age) with different linguistic profiles are sensitive to such nonarbitrary relationships. Here, the authors…

Voces (Voices): A Profile of Today's Latino College Students

ERIC Educational Resources Information Center

Santiago, Deborah A.

2007-01-01

Latinos are the youngest and fastest growing ethnic group in the United States. It is imperative that institutional leaders and decision makers have a better understanding of Latino students today in order to shape the policies and practices to serve college students in the future. Currently, disparate statistics about Latino students in higher…

Sputter crater formation in the case of microsecond pulsed glow discharge in a Grimm-type source. Comparison of direct current and radio frequency modes

NASA Astrophysics Data System (ADS)

Efimova, Varvara; Hoffmann, Volker; Eckert, Jürgen

2012-10-01

Depth profiling with pulsed glow discharge is a promising technique. The application of pulsed voltage for sputtering reduces the sputtering rate and thermal stress and hereby improves the analysis of thin layered and thermally fragile samples. However pulsed glow discharge is not well studied and this limits its practical use. The current work deals with the questions which usually arise when the pulsed mode is applied: Which duty cycle, frequency and pulse length must be chosen to get the optimal sputtering rate and crater shape? Are the well-known sputtering effects of the continuous mode valid also for the pulsed regime? Is there any difference between dc and rf pulsing in terms of sputtering? It is found that the pulse length is a crucial parameter for the crater shape and thermal effects. Sputtering with pulsed dc and rf modes is found to be similar. The observed sputtering effects at various pulsing parameters helped to interpret and optimize the depth resolution of GD OES depth profiles.

Profile shape optimization in multi-jet impingement cooling of dimpled topologies for local heat transfer enhancement

NASA Astrophysics Data System (ADS)

Negi, Deepchand Singh; Pattamatta, Arvind

2015-04-01

The present study deals with shape optimization of dimples on the target surface in multi-jet impingement heat transfer. Bezier polynomial formulation is incorporated to generate profile shapes for the dimple profile generation and a multi-objective optimization is performed. The optimized dimple shape exhibits higher local Nusselt number values compared to the reference hemispherical dimpled plate optimized shape which can be used to alleviate local temperature hot spots on target surface.

Observation of oscillatory radiation induced segregation profiles at grain boundaries in neutron irradiated 316 stainless steel using atom probe tomography

NASA Astrophysics Data System (ADS)

Barr, Christopher M.; Felfer, Peter J.; Cole, James I.; Taheri, Mitra L.

2018-06-01

Radiation induced segregation in austenitic Fe-Ni-Cr stainless steels is a key detrimental microstructural modification experienced in the current generation of light water reactors. In particular, Cr depletion at grain boundaries can be a significant factor in irradiation-assisted stress corrosion cracking. Therefore, having a complete knowledge and mechanistic understanding of radiation induced segregation at high dose and after a long thermal history is desired for continued sustainability of existing reactors. Here, we examine a 12% cold worked AISI 316 stainless steel hexagonal duct exposed in the lower dose, outer blanket region of the EBR-II reactor, by using advanced characterization and analysis techniques including atom probe tomography and analytical scanning transmission electron microscopy. Contrary to existing literature, we observe an oscillatory w-shape Cr and M-shape Ni concentration profile at 31 dpa. The presence and characterization through advanced atom probe tomography analysis of the w-shape Cr RIS profile is discussed in the context of the localized GB plane interfacial excess of the other major and minor alloying elements. The key finding of a co-segregation phenomena coupling Cr, Mo, and C is discussed in the context of the existing solute segregation literature under irradiation with emphasis on improved spatial and chemical resolution of atom probe tomography.

Evaluation of the 3-GeV proton beam profile at the spallation target of the JSNS

NASA Astrophysics Data System (ADS)

Meigo, Shin-ichiro; Noda, Fumiaki; Ishikura, Syuichi; Futakawa, Masatoshi; Sakamoto, Shinichi; Ikeda, Yujiro

2006-06-01

At JSNS, 3-GeV protons beam is delivered from rapid cycling synchrotron (RCS) to the spallation neutron target. In order to reduce the damage of pitting on the target container, the peak current density should be kept as small as possible. In this study, the beam profile at spallation neutron target is evaluated. The phase-space distribution, including the space-charge effect, is calculated with SIMPSONS code. The beam profile on the target is obtained with the transfer matrix from exit of RCS to the target. As for injection to RCS, two methods of correlated and anti-correlated painting are considered. By using anti-correlated painting for injection of beam at RCS, it is found the shape of beam becomes flatter than the distribution by using correlated painting. As other aspect for the study of target, in order to carry out target performance test especially for the study of pitting issue, it is better to have the beam profile variety from the beginning of facility. The adjustable range for the beam profile at the beginning is also studied. Although the beam shape is narrow and the duty is very low, the strong enough peak density is achievable equivalent as 1 MW.

Adaptive wing structures

NASA Astrophysics Data System (ADS)

Reed, John L., Jr.; Hemmelgarn, Christopher D.; Pelley, Bryan M.; Havens, Ernie

2005-05-01

Cornerstone Research Group, Inc. (CRG) is developing a unique adaptive wing structure intended to enhance the capability of loitering Unmanned Air Vehicles (UAVs). In order to tailor the wing design to a specific application, CRG has developed a wing structure capable of morphing in chord and increasing planform area by 80 percent. With these features, aircraft will be capable of optimizing their flight efficiency throughout the entire mission profile. The key benefit from this morphing design is increased maneuverability, resulting in improved effectiveness over the current design. During the development process CRG has overcome several challenges in the design of such a structure while incorporating advanced materials capable of maintaining aerodynamic shape and transferring aerodynamic loads while enabling crucial changes in planform shape. To overcome some of these challenges, CRG is working on integration of their shape memory polymer materials into the wing skin to enable seamless morphing. This paper will address the challenges associated with the development of a morphing aerospace structure capable of such large shape change, the materials necessary for enabling morphing capabilities, and the current status of the morphing program within CRG.

The effect of safety factor profile on transport in steady-state, high-performance scenarios

DOE PAGES

Holcomb, C. T.; Ferron, J. R.; Luce, T. C.; ...

2012-03-09

In this study, an analysis of the dependence of transport on the safety factor profile in high-performance, steady-state scenario discharges is presented. This is based on experimental scans of q 95 and q min taken with fixed β N, toroidal field, double-null plasma shape, divertor pumping, and electron cyclotron current drive input. The temperature and thermal diffusivity profiles were found to vary considerably with the q-profile, and these variations were significantly different for electrons and ions. With fixed q 95, both temperature profiles increase and broaden as q min is increased and the magnetic shear becomes low or negative inmore » the inner half radius, but these temperature profile changes are stronger for the electrons. Power balance calculations show the peak in the ion thermal diffusivity (χ i) at ρ – 0.6 – 0.8 increases with q 95 or q min.« less

Quantitative Understanding of SHAPE Mechanism from RNA Structure and Dynamics Analysis.

PubMed

Hurst, Travis; Xu, Xiaojun; Zhao, Peinan; Chen, Shi-Jie

2018-05-10

The selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) method probes RNA local structural and dynamic information at single nucleotide resolution. To gain quantitative insights into the relationship between nucleotide flexibility, RNA 3D structure, and SHAPE reactivity, we develop a 3D Structure-SHAPE Relationship model (3DSSR) to rebuild SHAPE profiles from 3D structures. The model starts from RNA structures and combines nucleotide interaction strength and conformational propensity, ligand (SHAPE reagent) accessibility, and base-pairing pattern through a composite function to quantify the correlation between SHAPE reactivity and nucleotide conformational stability. The 3DSSR model shows the relationship between SHAPE reactivity and RNA structure and energetics. Comparisons between the 3DSSR-predicted SHAPE profile and the experimental SHAPE data show correlation, suggesting that the extracted analytical function may have captured the key factors that determine the SHAPE reactivity profile. Furthermore, the theory offers an effective method to sieve RNA 3D models and exclude models that are incompatible with experimental SHAPE data.

The role of cross-shore tidal dynamics in controlling intertidal sediment exchange in mangroves in Cù Lao Dung, Vietnam

NASA Astrophysics Data System (ADS)

Bryan, Karin R.; Nardin, William; Mullarney, Julia C.; Fagherazzi, Sergio

2017-09-01

Mangroves are halophytic plants common in tropical and sub-tropical environments. Their roots and pneumatophores strongly affect intertidal hydrodynamics and related sediment transport. Here, we investigate the role tree and root structures may play in altering tidal currents and the effect of these currents on the development of intertidal landscapes in mangrove-dominated environments. We use a one-dimensional Delft3D model, forced using typical intertidal slopes and vegetation characteristics from two sites with contrasting slope on Cù Lao Dung within the Mekong Delta in Vietnam, to examine the vegetation controls on tidal currents and suspended sediment transport as the tides propagate into the forest. Model results show that vegetation characteristics at the seaward fringe determine the shape of the cross-shore bottom profile, with sparse vegetation leading to profiles that are close to linear, whereas with dense vegetation resulting in a convex intertidal topography. Examples showing different profile developments are provided from a variety of published studies, ranging from linear profiles in sandier sites, and distinctive convex profiles in muddier sites. As expected, profile differences in the model are caused by increased dissipation due to enhanced drag caused by vegetation; however, the reduction of flow shoreward in sparsely vegetated or non-vegetated cases was similar, indicating that shallowing of the profile and slope effects play a dominant role in dissipation. Here, tidal velocities are measured in the field using transects of Acoustic Doppler Current Profilers, and confirm that cross-shore tidal currents diminish quickly as they move over the fringe of the forest; they then stay fairly consistent within the outer few 100 m of the forest, indicating that the fringing environment is likely a region of deposition. An understanding of how vegetation controls the development of topography is critical to predicting the resilience of these sensitive intertidal areas to changes in inundation caused by sea-level rise.

Some Aspects of Advanced Tokamak Modeling in DIII-D

NASA Astrophysics Data System (ADS)

St John, H. E.; Petty, C. C.; Murakami, M.; Kinsey, J. E.

2000-10-01

We extend previous work(M. Murakami, et al., General Atomics Report GA-A23310 (1999).) done on time dependent DIII-D advanced tokamak simulations by introducing theoretical confinement models rather than relying on power balance derived transport coefficients. We explore using NBCD and off axis ECCD together with a self-consistent aligned bootstrap current, driven by the internal transport barrier dynamics generated with the GLF23 confinement model, to shape the hollow current profile and to maintain MHD stable conditions. Our theoretical modeling approach uses measured DIII-D initial conditions to start off the simulations in a smooth consistent manner. This mitigates the troublesome long lived perturbations in the ohmic current profile that is normally caused by inconsistent initial data. To achieve this goal our simulation uses a sequence of time dependent eqdsks generated autonomously by the EFIT MHD equilibrium code in analyzing experimental data to supply the history for the simulation.

Investigation of the plasma shaping effects on the H-mode pedestal structure using coupled kinetic neoclassical/MHD stability simulations

NASA Astrophysics Data System (ADS)

Pankin, A. Y.; Rafiq, T.; Kritz, A. H.; Park, G. Y.; Snyder, P. B.; Chang, C. S.

2017-06-01

The effects of plasma shaping on the H-mode pedestal structure are investigated. High fidelity kinetic simulations of the neoclassical pedestal dynamics are combined with the magnetohydrodynamic (MHD) stability conditions for triggering edge localized mode (ELM) instabilities that limit the pedestal width and height in H-mode plasmas. The neoclassical kinetic XGC0 code [Chang et al., Phys. Plasmas 11, 2649 (2004)] is used in carrying out a scan over plasma elongation and triangularity. As plasma profiles evolve, the MHD stability limits of these profiles are analyzed with the ideal MHD ELITE code [Snyder et al., Phys. Plasmas 9, 2037 (2002)]. Simulations with the XGC0 code, which includes coupled ion-electron dynamics, yield predictions for both ion and electron pedestal profiles. The differences in the predicted H-mode pedestal width and height for the DIII-D discharges with different elongation and triangularities are discussed. For the discharges with higher elongation, it is found that the gradients of the plasma profiles in the H-mode pedestal reach semi-steady states. In these simulations, the pedestal slowly continues to evolve to higher pedestal pressures and bootstrap currents until the peeling-ballooning stability conditions are satisfied. The discharges with lower elongation do not reach the semi-steady state, and ELM crashes are triggered at earlier times. The plasma elongation is found to have a stronger stabilizing effect than the plasma triangularity. For the discharges with lower elongation and lower triangularity, the ELM frequency is large, and the H-mode pedestal evolves rapidly. It is found that the temperature of neutrals in the scrape-off-layer (SOL) region can affect the dynamics of the H-mode pedestal buildup. However, the final pedestal profiles are nearly independent of the neutral temperature. The elongation and triangularity affect the pedestal widths of plasma density and electron temperature profiles differently. This provides a new mechanism of controlling the pedestal bootstrap current and the pedestal stability.

Investigation of the plasma shaping effects on the H-mode pedestal structure using coupled kinetic neoclassical/MHD stability simulations

DOE PAGES

Pankin, A. Y.; Rafiq, T.; Kritz, A. H.; ...

2017-06-08

The effects of plasma shaping on the H-mode pedestal structure are investigated. High fidelity kinetic simulations of the neoclassical pedestal dynamics are combined with the magnetohydrodynamic (MHD) stability conditions for triggering edge localized mode (ELM) instabilities that limit the pedestal width and height in H-mode plasmas. We use the neoclassical kinetic XGC0 code [Chang et al., Phys. Plasmas 11, 2649 (2004)] to carry out a scan over plasma elongation and triangularity. As plasma profiles evolve, the MHD stability limits of these profiles are analyzed with the ideal MHD ELITE code [Snyder et al., Phys. Plasmas 9, 2037 (2002)]. In simulationsmore » with the XGC0 code, which includes coupled ion-electron dynamics, yield predictions for both ion and electron pedestal profiles. The differences in the predicted H-mode pedestal width and height for the DIII-D discharges with different elongation and triangularities are discussed. For the discharges with higher elongation, it is found that the gradients of the plasma profiles in the H-mode pedestal reach semi-steady states. In these simulations, the pedestal slowly continues to evolve to higher pedestal pressures and bootstrap currents until the peeling-ballooning stability conditions are satisfied. The discharges with lower elongation do not reach the semi-steady state, and ELM crashes are triggered at earlier times. The plasma elongation is found to have a stronger stabilizing effect than the plasma triangularity. For the discharges with lower elongation and lower triangularity, the ELM frequency is large, and the H-mode pedestal evolves rapidly. It is found that the temperature of neutrals in the scrape-off-layer (SOL) region can affect the dynamics of the H-mode pedestal buildup. But the final pedestal profiles are nearly independent of the neutral temperature. The elongation and triangularity affect the pedestal widths of plasma density and electron temperature profiles differently. This provides a new mechanism of controlling the pedestal bootstrap current and the pedestal stability.« less

Investigation of the plasma shaping effects on the H-mode pedestal structure using coupled kinetic neoclassical/MHD stability simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pankin, A. Y.; Rafiq, T.; Kritz, A. H.

The effects of plasma shaping on the H-mode pedestal structure are investigated. High fidelity kinetic simulations of the neoclassical pedestal dynamics are combined with the magnetohydrodynamic (MHD) stability conditions for triggering edge localized mode (ELM) instabilities that limit the pedestal width and height in H-mode plasmas. We use the neoclassical kinetic XGC0 code [Chang et al., Phys. Plasmas 11, 2649 (2004)] to carry out a scan over plasma elongation and triangularity. As plasma profiles evolve, the MHD stability limits of these profiles are analyzed with the ideal MHD ELITE code [Snyder et al., Phys. Plasmas 9, 2037 (2002)]. In simulationsmore » with the XGC0 code, which includes coupled ion-electron dynamics, yield predictions for both ion and electron pedestal profiles. The differences in the predicted H-mode pedestal width and height for the DIII-D discharges with different elongation and triangularities are discussed. For the discharges with higher elongation, it is found that the gradients of the plasma profiles in the H-mode pedestal reach semi-steady states. In these simulations, the pedestal slowly continues to evolve to higher pedestal pressures and bootstrap currents until the peeling-ballooning stability conditions are satisfied. The discharges with lower elongation do not reach the semi-steady state, and ELM crashes are triggered at earlier times. The plasma elongation is found to have a stronger stabilizing effect than the plasma triangularity. For the discharges with lower elongation and lower triangularity, the ELM frequency is large, and the H-mode pedestal evolves rapidly. It is found that the temperature of neutrals in the scrape-off-layer (SOL) region can affect the dynamics of the H-mode pedestal buildup. But the final pedestal profiles are nearly independent of the neutral temperature. The elongation and triangularity affect the pedestal widths of plasma density and electron temperature profiles differently. This provides a new mechanism of controlling the pedestal bootstrap current and the pedestal stability.« less

Overcoming the Triad of Rural Health Disparities: How Local Culture, Lack of Economic Opportunity, and Geographic Location Instigate Health Disparities

ERIC Educational Resources Information Center

Thomas, Tami L.; DiClemente, Ralph; Snell, Samuel

2014-01-01

Objective: To discuss how the effects of culture, economy, and geographical location intersect to form a gestalt triad determining health-related disparities in rural areas. Methods: We critically profile each component of the deterministic triad in shaping current health-related disparities in rural areas; evaluate the uniquely composed…

Universal analytical scattering form factor for shell-, core-shell, or homogeneous particles with continuously variable density profile shape.

PubMed

Foster, Tobias

2011-09-01

A novel analytical and continuous density distribution function with a widely variable shape is reported and used to derive an analytical scattering form factor that allows us to universally describe the scattering from particles with the radial density profile of homogeneous spheres, shells, or core-shell particles. Composed by the sum of two Fermi-Dirac distribution functions, the shape of the density profile can be altered continuously from step-like via Gaussian-like or parabolic to asymptotically hyperbolic by varying a single "shape parameter", d. Using this density profile, the scattering form factor can be calculated numerically. An analytical form factor can be derived using an approximate expression for the original Fermi-Dirac distribution function. This approximation is accurate for sufficiently small rescaled shape parameters, d/R (R being the particle radius), up to values of d/R ≈ 0.1, and thus captures step-like, Gaussian-like, and parabolic as well as asymptotically hyperbolic profile shapes. It is expected that this form factor is particularly useful in a model-dependent analysis of small-angle scattering data since the applied continuous and analytical function for the particle density profile can be compared directly with the density profile extracted from the data by model-free approaches like the generalized inverse Fourier transform method. © 2011 American Chemical Society

Influence of low-temperature resistivity on fast electron transport in solids: scaling to fast ignition electron beam parameters

NASA Astrophysics Data System (ADS)

McKenna, P.; MacLellan, D. A.; Butler, N. M. H.; Dance, R. J.; Gray, R. J.; Robinson, A. P. L.; Neely, D.; Desjarlais, M. P.

2015-06-01

The role of low-temperature electrical resistivity in defining the transport properties of mega-Ampere currents of fast (MeV) electrons in solids is investigated using 3D hybrid particle-in-cell (PIC) simulations. By considering resistivity profiles intermediate to the ordered (lattice) and disordered forms of two example materials, lithium and silicon, it is shown that both the magnitude of the resistivity and the shape of the resistivity-temperature profile at low temperatures strongly affect the self-generated resistive magnetic fields and the onset of resistive instabilities, and thus the overall fast electron beam transport pattern. The scaling of these effects to the giga-Ampere electron currents required for the fast ignition scheme for inertial fusion is also explored.

A summary report on the search for current technologies and developers to develop depth profiling/physical parameter end effectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Q.H.

1994-09-12

This report documents the search strategies and results for available technologies and developers to develop tank waste depth profiling/physical parameter sensors. Sources searched include worldwide research reports, technical papers, journals, private industries, and work at Westinghouse Hanford Company (WHC) at Richland site. Tank waste physical parameters of interest are: abrasiveness, compressive strength, corrosiveness, density, pH, particle size/shape, porosity, radiation, settling velocity, shear strength, shear wave velocity, tensile strength, temperature, viscosity, and viscoelasticity. A list of related articles or sources for each physical parameters is provided.

Ultra-narrow band diode lasers with arbitrary pulse shape modulation (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ryasnyanskiy, Aleksandr I.; Smirnov, Vadim; Mokhun, Oleksiy; Glebov, Alexei L.; Glebov, Leon B.

2017-03-01

Wideband emission spectra of laser diode bars (several nanometers) can be largely narrowed by the usage of thick volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass. Such narrowband systems, with GHz-wide emission spectra, found broad applications for Diode Pumped Alkali vapor Lasers, optically pumped rare gas metastable lasers, Spin Exchange Optical Pumping, atom cooling, etc. Although the majority of current applications of narrow line diode lasers require CW operation, there are a variety of fields where operation in a different pulse mode regime is necessary. Commercial electric pulse generators can provide arbitrary current pulse profiles (sinusoidal, rectangular, triangular and their combinations). The pulse duration and repetition rate however, have an influence on the laser diode temperature, and therefore, the emitting wavelength. Thus, a detailed analysis is needed to understand the correspondence between the optical pulse profiles from a diode laser and the current pulse profiles; how the pulse profile and duty cycle affects the laser performance (e.g. the wavelength stability, signal to noise ratio, power stability etc.). We present the results of detailed studies of the narrowband laser diode performance operating in different temporal regimes with arbitrary pulse profiles. The developed narrowband (16 pm) tunable laser systems at 795 nm are capable of operating in different pulse regimes while keeping the linewidth, wavelength, and signal-to-noise ratio (>20 dB) similar to the corresponding CW modules.

Evaluation of the in-service safety performance of safety-shape and vertical concrete barriers.

DOT National Transportation Integrated Search

2011-12-16

Roadside concrete barriers have been widely used to protect errant motorists from hitting : roadside hazards or obstacles. Two concrete barrier profiles, vertical and safety-shape, have been used : for this purpose. The safety-shape profile has been ...

Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U

DOE PAGES

Boyer, M. D.; Battaglia, D. J.; Mueller, D.; ...

2018-01-25

Here, the upgrade to the National Spherical Torus eXperiment (NSTX-U) included two main improvements: a larger center-stack, enabling higher toroidal field and longer pulse duration, and the addition of three new tangentially aimed neutral beam sources, which increase available heating and current drive, and allow for flexibility in shaping power, torque, current, and particle deposition profiles. To best use these new capabilities and meet the high-performance operational goals of NSTX-U, major upgrades to the NSTX-U control system (NCS) hardware and software have been made. Several control algorithms, including those used for real-time equilibrium reconstruction and shape control, have been upgradedmore » to improve and extend plasma control capabilities. As part of the commissioning phase of first plasma operations, the shape control system was tuned to control the boundary in both inner-wall limited and diverted discharges. It has been used to accurately track the requested evolution of the boundary (including the size of the inner gap between the plasma and central solenoid, which is a challenge for the ST configuration), X-point locations, and strike point locations, enabling repeatable discharge evolutions for scenario development and diagnostic commissioning.« less

Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyer, M. D.; Battaglia, D. J.; Mueller, D.

Here, the upgrade to the National Spherical Torus eXperiment (NSTX-U) included two main improvements: a larger center-stack, enabling higher toroidal field and longer pulse duration, and the addition of three new tangentially aimed neutral beam sources, which increase available heating and current drive, and allow for flexibility in shaping power, torque, current, and particle deposition profiles. To best use these new capabilities and meet the high-performance operational goals of NSTX-U, major upgrades to the NSTX-U control system (NCS) hardware and software have been made. Several control algorithms, including those used for real-time equilibrium reconstruction and shape control, have been upgradedmore » to improve and extend plasma control capabilities. As part of the commissioning phase of first plasma operations, the shape control system was tuned to control the boundary in both inner-wall limited and diverted discharges. It has been used to accurately track the requested evolution of the boundary (including the size of the inner gap between the plasma and central solenoid, which is a challenge for the ST configuration), X-point locations, and strike point locations, enabling repeatable discharge evolutions for scenario development and diagnostic commissioning.« less

Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U

NASA Astrophysics Data System (ADS)

Boyer, M. D.; Battaglia, D. J.; Mueller, D.; Eidietis, N.; Erickson, K.; Ferron, J.; Gates, D. A.; Gerhardt, S.; Johnson, R.; Kolemen, E.; Menard, J.; Myers, C. E.; Sabbagh, S. A.; Scotti, F.; Vail, P.

2018-03-01

The upgrade to the National Spherical Torus eXperiment (NSTX-U) included two main improvements: a larger center-stack, enabling higher toroidal field and longer pulse duration, and the addition of three new tangentially aimed neutral beam sources, which increase available heating and current drive, and allow for flexibility in shaping power, torque, current, and particle deposition profiles. To best use these new capabilities and meet the high-performance operational goals of NSTX-U, major upgrades to the NSTX-U control system (NCS) hardware and software have been made. Several control algorithms, including those used for real-time equilibrium reconstruction and shape control, have been upgraded to improve and extend plasma control capabilities. As part of the commissioning phase of first plasma operations, the shape control system was tuned to control the boundary in both inner-wall limited and diverted discharges. It has been used to accurately track the requested evolution of the boundary (including the size of the inner gap between the plasma and central solenoid, which is a challenge for the ST configuration), X-point locations, and strike point locations, enabling repeatable discharge evolutions for scenario development and diagnostic commissioning.

Shape Models of Asteroids as a Missing Input for Bulk Density Determinations

NASA Astrophysics Data System (ADS)

Hanuš, Josef

2015-07-01

To determine a meaningful bulk density of an asteroid, both accurate volume and mass estimates are necessary. The volume can be computed by scaling the size of the 3D shape model to fit the disk-resolved images or stellar occultation profiles, which are available in the literature or through collaborations. This work provides a list of asteroids, for which (i) there are already mass estimates with reported uncertainties better than 20% or their mass will be most likely determined in the future from Gaia astrometric observations, and (ii) their 3D shape models are currently unknown. Additional optical lightcurves are necessary to determine the convex shape models of these asteroids. The main aim of this article is to motivate the observers to obtain lightcurves of these asteroids, and thus contribute to their shape model determinations. Moreover, a web page https://asteroid-obs.oca.eu, which maintains an up-to-date list of these objects to assure efficiency and to avoid any overlapping efforts, was created.

LETTER: Test of Te profile invariance by sensitivity studies

NASA Astrophysics Data System (ADS)

Becker, G.

1992-06-01

The response of the electron temperature profile shape to variations of the electron heating and density profiles is investigated in different confinement regimes. It is shown that the changes in rTe = -Te/(dTe/dr) exceed the measurement error if the shape of the electron heat diffusivity χe(r) is kept fixed. The observed constancy of rTe(r) in the outer half of the plasma is incompatible with such a fixed χe(r) shape, i.e., a Te profile constraining mechanism must be present. Local transport laws of the form χe varies as rTe-α with α gtrsim 4 and χe propto (dTe/dr)α with α >= 2 yield the experimental stiffness of the Te(r) shape but conflict with empirical χe scalings. These results support the model of a self-organizing and adjusting χe(r) causing Te profile invariance

Predicting ozone profile shape from satellite UV spectra

NASA Astrophysics Data System (ADS)

Xu, Jian; Loyola, Diego; Romahn, Fabian; Doicu, Adrian

2017-04-01

Identifying ozone profile shape is a critical yet challenging job for the accurate reconstruction of vertical distributions of atmospheric ozone that is relevant to climate change and air quality. Motivated by the need to develop an approach to reliably and efficiently estimate vertical information of ozone and inspired by the success of machine learning techniques, this work proposes a new algorithm for deriving ozone profile shapes from ultraviolet (UV) absorption spectra that are recorded by satellite instruments, e.g. GOME series and the future Sentinel missions. The proposed algorithm formulates this particular inverse problem in a classification framework rather than a conventional inversion one and places an emphasis on effectively characterizing various profile shapes based on machine learning techniques. Furthermore, a comparison of the ozone profiles from real GOME-2 data estimated by our algorithm and the classical retrieval algorithm (Optimal Estimation Method) is performed.

Surface-brightness profiles of dwarf galaxies in the NGC 5044 Group: Implications for the luminosity-shape and scalelength-shape relationships as distance indicators

NASA Astrophysics Data System (ADS)

Young, C. K.; Currie, M. J.

2001-04-01

In a recent paper, which presents CCD photometry for fifteen dwarf and intermediate early-type galaxies in the NGC 5044 Group, it has been claimed that ``a few relatively bright galaxies with ``convex'' profiles destroy the known relation between total magnitude and the ``shape'' parameter... thus ruling out the use of this relation as a distance indicator for individual galaxies''. In the same paper, further reasons were cited supposedly ``limiting also its use as a distance indicator for groups of galaxies''. We demonstrate that none of the three relatively bright galaxies cited as possessing ``convex'' profiles actually has a convex profile, and that one of these objects should be excluded because it is a late-type galaxy. Of the two remaining objects, one has an anomalous profile shape whilst the other is brighter than one might expect from its colour alone. However, we show that all of the other issues raised have already been accounted for by Young & Currie (\\cite{you94}, \\cite{you95} & \\cite{you98}). The main implications of the new observations are: (1) that the case of one galaxy with an anomalous profile shape, N42, highlights the need for some a priori criteria to be defined in order to establish objectively which objects are not suitable for distance determinations; and (2) on the basis of another unusual galaxy, N50, colour has now been shown to be a poorer discriminant between objects of the same profile shape and scalelength (but of different central surface brightness) than previously thought. How significant this latter problem is depends on how common N50-like objects are. This consideration reinforces the case for always using the more general scalelength-shape relationship of Young & Currie (\\cite{you95}) in preference to the luminosity-shape one of Young & Currie (\\cite{you94}). Reassuringly, through a re-analysis of the same CCD photometry, we find that NGC 5044 Group galaxies observe a tight scalelength-shape relationship. This finding supports the view that the scalelength-shape relationship is a viable distance indicator.

MO-FG-CAMPUS-IeP2-01: Characterization of Beam Shaping Filters and Photon Spectra From HVL Profiles in CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bujila, R; Royal Institute of Technology, Stockholm; Kull, L

Purpose: Advanced dosimetry in CT (e.g. the Monte Carlo method) requires an accurate characterization of the shaped filter and radiation quality used during a scan. The purpose of this work was to develop a method where half value layer (HVL) profiles along shaped filters could be made. From the HVL profiles the beam shaping properties and effective photon spectrum for a particular scan can be inferred. Methods: A measurement rig was developed to allow determinations of the HVL under a scatter-free narrow-beam geometry and constant focal spot to ionization chamber distance for different fan angles. For each fan angle themore » HVL is obtained by fitting the transmission of radiation through different thicknesses of an Al absorber (type 1100) using an appropriate model. The effective Al thickness of shaped filters and effective photon spectra are estimated using a model of photon emission from a Tungsten anode. This method is used to obtain the effective photon spectra and effective Al thickness of shaped filters for a CT scanner recently introduced to the market. Results: This study resulted in a set of effective photon spectra (central ray) for each kVp along with effective Al thicknesses of the different shaped filters. The effective photon spectra and effective Al thicknesses of shaped filters were used to obtain numerically approximated HVL profiles and compared to measured HVL profiles (mean absolute percentage error = 0.02). The central axis HVL found in the vendor’s technical documentation were compared to approximated HVL values (mean absolute percentage error = 0.03). Conclusion: This work has resulted in a unique method of measuring HVL profiles along shaped filters in CT. Further the effective photon spectra and the effective Al thicknesses of shaped filters that were obtained can be incorporated into Monte Carlo simulations.« less

Application of the Hartmann-Tran profile to analysis of H2O spectra

NASA Astrophysics Data System (ADS)

Lisak, D.; Cygan, A.; Bermejo, D.; Domenech, J. L.; Hodges, J. T.; Tran, H.

2015-10-01

The Hartmann-Tran profile (HTP), which has been recently recommended as a new standard in spectroscopic databases, is used to analyze spectra of several lines of H2O diluted in N2, SF6, and in pure H2O. This profile accounts for various mechanisms affecting the line-shape and can be easily computed in terms of combinations of the complex Voigt profile. A multi-spectrum fitting procedure is implemented to simultaneously analyze spectra of H2O transitions acquired at different pressures. Multi-spectrum fitting of the HTP to a theoretical model confirms that this profile provides an accurate description of H2O line-shapes in terms of residuals and accuracy of fitted parameters. This profile and its limiting cases are also fit to measured spectra for three H2O lines in different vibrational bands. The results show that it is possible to obtain accurate HTP line-shape parameters when measured spectra have a sufficiently high signal-to-noise ratio and span a broad range of collisional-to-Doppler line widths. Systematic errors in the line area and differences in retrieved line-shape parameters caused by the overly simplistic line-shape models are quantified. Also limitations of the quadratic speed-dependence model used in the HTP are demonstrated in the case of an SF6 broadened H2O line, which leads to a strongly asymmetric line-shape.

High-resolution field shaping utilizing a masked multileaf collimator.

PubMed

Williams, P C; Cooper, P

2000-08-01

Multileaf collimators (MLCs) have become an important tool in the modern radiotherapy department. However, the current limit of resolution (1 cm at isocentre) can be too coarse for acceptable shielding of all fields. A number of mini- and micro-MLCs have been developed, with thinner leaves to achieve approved resolution. Currently however, such devices are limited to modest field sizes and stereotactic applications. This paper proposes a new method of high-resolution beam collimation by use of a tertiary grid collimator situated below the conventional MLC. The width of each slit in the grid is a submultiple of the MLC width. A composite shaped field is thus built up from a series of subfields, with the main MLC defining the length of each strip within each subfield. Presented here are initial findings using a prototype device. The beam uniformity achievable with such a device was examined by measuring transmission profiles through the grid using a diode. Profiles thus measured were then copied and superposed to generate composite beams, from which the uniformity achievable could be assessed. With the average dose across the profile normalized to 100%, hot spots up to 5.0% and troughs of 3% were identified for a composite beam of 2 x 5.0 mm grids, as measured at Dmax for a 6 MV beam. For a beam composed from 4 x 2.5 mm grids, the maximum across the profile was 3.0% above the average, and the minimum 2.5% below. Actual composite profiles were also formed using the integrating properties of film, with the subfield indexing performed using an engineering positioning stage. The beam uniformity for these fields compared well with that achieved in theory using the diode measurements. Finally sine wave patterns were generated to demonstrate the potential improvements in field shaping and conformity using this device as opposed to the conventional MLC alone. The scalloping effect on the field edge commonly seen on MLC fields was appreciably reduced by use of 2 x 5.0 mm grids, and still further by the use of 4 x 2.5 mm grids, as would be expected. This was also achieved with a small or negligible broadening of the beam penumbra as measured at Dmax.

Numerical investigation of the effect of driving voltage pulse shapes on the characteristics of low-pressure argon dielectric barrier discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eslami, E., E-mail: eeslami@iust.ac.ir; Barjasteh, A.; Morshedian, N.

2015-06-15

In this work, we numerically compare the effect of a sinusoidal, triangular, and rectangular pulsed voltage profile on the calculated particle production, electric current, and gas voltage in a dielectric barrier discharge. The total argon gas pressure of 400 Pa, the distance between dielectrics of 5 mm, the dielectric thickness of 0.7 mm, and the temperature of T = 300 K were considered as input parameters. The different driving voltage pulse shapes (triangular, rectangular, and sinusoidal) are considered as applied voltage with a frequency of 7 kHz and an amplitude of 700 V peak to peak. It is shown thatmore » applying a rectangular voltage, as compared with a sinusoidal or triangle voltage, increases the current peak, while the peak width is decreased. Higher current density is related to high production of charged particles, which leads to the generation of some highly active species, such as Ar* (4s level), and Ar** (4p level) in the gap.« less

Differential Sensitization of Parenting on Early Adolescent Cortisol: Moderation by Profiles of Maternal Stress

PubMed Central

Martin, Christina Gamache; Kim, Hyoun K.; Fisher, Philip A.

2016-01-01

The hypothalamic-pituitary-adrenal (HPA) axis is a critical component of the body’s stress-response neurobiological system, and its development and functioning are shaped by the social environment. Much of our understanding of the effects of the caregiving environment on the HPA axis is based on a) parenting in young children and b) individual maternal stressors, such as depression. Yet, less is known about how parenting behaviors and maternal stressors interact to influence child cortisol regulation, particularly in older children. With an ethnically diverse sample of 199 mothers and their early adolescent children (M = 11.00 years; 54% female), a profile analytic approach was used to investigate how multiple phenotypes of maternal stress co-occur and moderate the relation between parenting behaviors and youths’ diurnal cortisol rhythms. Latent profile analysis yielded 4 profiles: current parenting stress, concurrent parenting and childhood stress, childhood stress, and low stress. For mothers with the concurrent parenting and childhood stress profile, inconsistent discipline, poor parental supervision, and harsh caregiving behaviors each were related to flattened diurnal cortisol rhythms in their adolescents. For mothers with the current parenting stress and childhood stress profiles, their use of inconsistent discipline was associated with flattened diurnal cortisol rhythms in their adolescents. For mothers with the low stress profile, none of the parenting behaviors was related to their adolescents’ cortisol regulation. Findings suggest that based on mothers’ stress profile, parenting behaviors are differentially related to youths’ diurnal cortisol rhythms. Implications for parenting interventions are discussed. PMID:26859701

The shape parameter and its modification for defining coastal profiles

NASA Astrophysics Data System (ADS)

Türker, Umut; Kabdaşli, M. Sedat

2009-03-01

The shape parameter is important for the theoretical description of the sandy coastal profiles. This parameter has previously been defined as a function of the sediment-settling velocity. However, the settling velocity cannot be characterized over a wide range of sediment grains. This, in turn, limits the calculation of the shape parameter over a wide range. This paper provides a simpler and faster analytical equation to describe the shape parameter. The validity of the equation has been tested and compared with the previously estimated values given in both graphical and tabular forms. The results of this study indicate that the analytical solutions of the shape parameter improved the usability of profile better than graphical solutions, predicting better results both at the surf zone and offshore.

The A and m coefficients in the Bruun/Dean equilibrium profile equation seen from the Arctic

USGS Publications Warehouse

Are, F.; Reimnitz, E.

2008-01-01

The Bruun/Dean relation between water depth and distance from the shore with a constant profile shape factor is widely used to describe shoreface profiles in temperate environments. However, it has been shown that the sediment scale parameter (A) and the profile shape factor (m) are interrelated variables. An analysis of 63 Arctic erosional shoreface profiles shows that both coefficients are highly variable. Relative frequency of the average m value is only 16% by the class width 0.1. No other m value frequency exceeds 21%. Therefore, there is insufficient reason to use average m to characterize Arctic shoreface profile shape. The shape of each profile has a definite combination of A and m values. Coefficients A and m show a distinct inverse relationship, as in temperate climate. A dependence of m values on coastal sediment grain size is seen, and m decreases with increasing grain size. With constant m = 0.67, parameter A obtains a dimension unit m1/3. But A equals the water depth in meters 1 m from the water edge. This fact and the variability of parameter m testify that the Bruun/Dean equation is essentially an empirical formula. There is no need to give any measurement unit to parameter A. But the International System of Units (SI) has to be used in applying the Bruun/Dean equation for shoreface profiles. A comparison of the shape of Arctic shoreface profiles with those of temperate environments shows surprising similarity. Therefore, the conclusions reached in this Arctic paper seem to apply also to temperate environments.

Spiral biasing adaptor for use in Si drift detectors and Si drift detector arrays

DOEpatents

Li, Zheng; Chen, Wei

2016-07-05

A drift detector array, preferably a silicon drift detector (SDD) array, that uses a low current biasing adaptor is disclosed. The biasing adaptor is customizable for any desired geometry of the drift detector single cell with minimum drift time of carriers. The biasing adaptor has spiral shaped ion-implants that generate the desired voltage profile. The biasing adaptor can be processed on the same wafer as the drift detector array and only one biasing adaptor chip/side is needed for one drift detector array to generate the voltage profiles on the front side and back side of the detector array.

Radiating pattern of surge-current-induced THz light in near-field and far-field zone.

PubMed

Han, J W; Choi, Y G; Lee, J S

2018-04-25

We generate the THz wave on the surface of an unbiased GaAs crystal by illuminating femtosecond laser pulses with a 45° incidence angle, and investigate its propagation properties comprehensively both in a near-field and in a far-field zone by performing a knife-edge scan measurement. In the near-field zone, i.e. 540 μm away from the generation point, we found that the beam simply takes a Gaussian shape of which width follows well a behavior predicted by a paraxial wave equation. In the far-field zone, on the other hand, it takes a highly anisotropic shape; whereas the beam profile maintains a Gaussian shape along the normal to the plane of incidence, it takes satellite peak structures along the direction in parallel to the plane of incidence. From the comparison with simulation results obtained by using a dipole radiation model, we demonstrated that this irregular beam pattern is attributed to the combined effect of the position-dependent phase retardation of the THz waves and the diffraction-limited size of the initial beam which lead to the interference of the waves in the far-field zone. Also, we found that this consideration accounting for a crossover of THz beam profile to the anisotropic non-Gaussian beam in the far-field zone can be applied for a comprehensive understanding of several other THz beam profiles obtained previously in different configurations.

High beta-N experiments at JET

NASA Astrophysics Data System (ADS)

Challis, Clive

2007-11-01

JET has investigated the performance potential and limitations of highly triangular plasmas relevant to fully non-inductive tokamak operation. The q-profile shape has been varied from cases with highly negative core magnetic shear to low shear with q0 close to 1, allowing the effect on confinement and stability to be studied. Operation with beta-N above the no-wall `limit' has been demonstrated for durations comparable with the resistive time and direct measurements of the no-wall beta have been developed as a tool for systematic performance optimization. Regimes have been developed with ITBs at reduced plasma current and toroidal field (1.2-1.5MA/2.3-2.7T) to obtain high values of beta-N and beta-P with either impurity seeding or quasi-double-null plasma configurations used to mitigate ELMs. The importance of the q-profile shape for performance optimization has been demonstrated in plasmas without ITBs (1.2MA/1.8T) with low values of minimum q (1-2) providing access to the highest beta-N (above 3).

Hohlraum design for the LMJ ignition target

NASA Astrophysics Data System (ADS)

Malinie, G.; Cherfils, C.; Gauthier, P.; Lambert, F.; Monteil, M. C.

2011-10-01

First experiments with the Laser MegaJoule (LMJ) are scheduled to be performed in 2014. The current nominal point design for ignition with 160 beams on the LMJ has been described in. It consists of an indirectly driven A943 capsule, with a plastic ablator doped with Germanium. This capsule is mounted in the center of a Rugby-shaped hohlraum, which is filled with a low density H/He gas, and has a gold-uranium cocktail wall lined with pure gold. We investigate the influence of two key parameters of the hohlraum design: the radius of the laser entrance holes (LEHs), and the thickness of the cocktail layer. Since the Rugby shape of the nominal point design is that of a half-ellipse going from the hohlraum waist to the LEH, any change in the LEH radius has a global effect on the hohlraum shape. Taking into account the current laser spot profiles of the LMJ and using 2D integrated calculations with our FCI2 radiation hydrodynamics code, we assess the flexiblility we have to reduce the LEH radius and/or the cocktail layer thickness.

Study on the Characteristics of Plasma Profiles in Improved Confinement Plasmas in HT-7 Superconducting Tokamak

NASA Astrophysics Data System (ADS)

Zhang, Shouyin; Gao, Xiang; Li, Jiangang; Wan, Baonian; Kuang, Guangli; Mao, Jianshan; Zhang, Xiaodong; Xie, Jikang; Wan, Yuanxi; Team HT-7

2000-10-01

In HT-7 superconducting tokamak of circular limiter configuration (R0=122cm, a=30cm, Bt:1 ~2.2T), plasma profiles were modified and controlled by means of gas puffing, supersonic molecule injection, pellet injection, ICRF and IBW heating as well as LHW heating and current drive; improved plasma confinements were achieved either by application of one of the above measures or by the combination of them, study of the effects of the characteristics of plasma profiles on plasma confinements were performed. The results show that in most of the improved confinement plasmas in HT-7, there are very steep and strong peeking electron temperature profiles in core plasma, and/or large decrease of local temperature in radius of 0.5 ~0.7a which makes temperature gradient steeper when improvements begin, as temperature profile evolves back to previous normal shape the improvements end. Electron density profile and soft X-ray profiles were studied as well. This research was supported under Natural Science Foundation of China contract No.19905010.

The role of stellar radial motions in shaping galaxy surface brightness profiles

NASA Astrophysics Data System (ADS)

Ruiz-Lara, T.; Few, C. G.; Florido, E.; Gibson, B. K.; Pérez, I.; Sánchez-Blázquez, P.

2017-12-01

Aims: The physics driving features such as breaks observed in galaxy surface brightness (SB) profiles remains contentious. Here, we assess the importance of stellar radial motions in shaping their characteristics. Methods: We use the simulated Milky Way-mass cosmological discs from the Ramses Disc Environment Study (RaDES) to characterise the radial redistribution of stars in galaxies displaying type-I (pure exponentials), II (downbending), and III (upbending) SB profiles. We compare radial profiles of the mass fractions and the velocity dispersions of different sub-populations of stars according to their birth and current location. Results: Radial redistribution of stars is important in all galaxies regardless of their light profiles. Type-II breaks seem to be a consequence of the combined effects of outward-moving and accreted stars. The former produce shallower inner profiles (lack of stars in the inner disc) and accumulate material around the break radius and beyond, strengthening the break; the latter can weaken or even convert the break into a pure exponential. Further accretion from satellites can concentrate material in the outermost parts, leading to type-III breaks that can coexist with type-II breaks, but situated further out. Type-III galaxies would be the result of an important radial redistribution of material throughout the entire disc, as well as a concentration of accreted material in the outskirts. In addition, type-III galaxies display the most efficient radial redistribution and the largest number of accreted stars, followed by type-I and II systems, suggesting that type-I galaxies may be an intermediate case between types II and III. In general, the velocity dispersion profiles of all galaxies tend to flatten or even increase around the locations where the breaks are found. The age and metallicity profiles are also affected, exhibiting different inner gradients depending on their SB profile, being steeper in the case of type-II systems (as found observationally). The steep type-II profiles might be inherent to their formation rather than acquired via radial redistribution.

Geomorphic effectiveness of a long profile shape and the role of inherent geological controls in the Himalayan hinterland area of the Ganga River basin, India

NASA Astrophysics Data System (ADS)

Sonam; Jain, Vikrant

2018-03-01

Long profiles of rivers provide a platform to analyse interaction between geological and geomorphic processes operating at different time scales. Identification of an appropriate model for river long profile becomes important in order to establish a quantitative relationship between the profile shape, its geomorphic effectiveness, and inherent geological characteristics. This work highlights the variability in the long profile shape of the Ganga River and its major tributaries, its impact on stream power distribution pattern, and role of the geological controls on it. Long profile shapes are represented by the sum of two exponential functions through the curve fitting method. We have shown that coefficients of river long profile equations are governed by the geological characteristics of subbasins. These equations further define the spatial distribution pattern of stream power and help to understand stream power variability in different geological terrains. Spatial distribution of stream power in different geological terrains successfully explains spatial variability in geomorphic processes within the Himalayan hinterland area. In general, the stream power peaks of larger rivers lie in the Higher Himalaya, and rivers in the eastern hinterland area are characterised by the highest magnitude of stream power.

Full area covered 3D profile measurement of special-shaped optics based on a new prototype non-contact profiler

NASA Astrophysics Data System (ADS)

Du, Hui-Lin; Zhou, Zhao-Zhong; Sun, Ze-Qing; Ju, Bing-Feng; Xu, Shaoning; Sun, Anyu

2017-06-01

A new prototype non-contact profiler based on surface tracking has been specially developed. Surface tracking is carried out by a specially designed dual stage probe system with the aid of a four-Degree Of Freedom high-precision motion platform. The dual stage probe system keeps a short-range optical probe constantly tracking the surface by a self-developed voice coil motor servo, by which a wide measuring range of up to 10 mm is realized. The system performance evaluation including resolution, repeatability, and scanning speed proved the good capability of the new prototype non-contact profiler. To realize a full area covered 3D profile measurement of special-shaped optics within one scanning procedure, a signal intensity monitor integrated in the surface tracking controller is specially developed. In the experiment, a snip-single-corner-rectangular-shaped freeform surface was successfully measured over full area by the new non-contact profiler. This work provides an effective solution for 3D profile measurement of special-shaped optical surfaces over full reflecting area. Experimental results demonstrate that the proposed measuring system is of great significance in quality evaluation of optical surfaces.

Full area covered 3D profile measurement of special-shaped optics based on a new prototype non-contact profiler.

PubMed

Du, Hui-Lin; Zhou, Zhao-Zhong; Sun, Ze-Qing; Ju, Bing-Feng; Xu, Shaoning; Sun, Anyu

2017-06-01

A new prototype non-contact profiler based on surface tracking has been specially developed. Surface tracking is carried out by a specially designed dual stage probe system with the aid of a four-Degree Of Freedom high-precision motion platform. The dual stage probe system keeps a short-range optical probe constantly tracking the surface by a self-developed voice coil motor servo, by which a wide measuring range of up to 10 mm is realized. The system performance evaluation including resolution, repeatability, and scanning speed proved the good capability of the new prototype non-contact profiler. To realize a full area covered 3D profile measurement of special-shaped optics within one scanning procedure, a signal intensity monitor integrated in the surface tracking controller is specially developed. In the experiment, a snip-single-corner-rectangular-shaped freeform surface was successfully measured over full area by the new non-contact profiler. This work provides an effective solution for 3D profile measurement of special-shaped optical surfaces over full reflecting area. Experimental results demonstrate that the proposed measuring system is of great significance in quality evaluation of optical surfaces.

New Vary-Chap Profile of the Topside Ionosphere Electron Density Distribution for use with the IRI Model and the GIRO Real-Time Data

NASA Technical Reports Server (NTRS)

Nsumei, Patrick; Reinisch, Bodo W.; Huang, Xueqin; Bilitza, Dieter

2012-01-01

A new Vary-Chap function is introduced for the empirical modeling of the electron density N(h) profile in the topside ionosphere that uses a shape function S(h) in the generalized Chapman function. The Vary-Chap profile extends the bottomside profile that is specified by the IRI model or measured by the Global Ionospheric Radio Observatory (GIRO) to the altitude of the ISIS-2 satellite. Some 80,000 topside profiles, measured by the topside sounder on the ISIS-2 satellite were analyzed, and the shape function S(h) was calculated for each profile. A parameterized function S*(h), composed of two sub-functions S1(h) and S2(h), is fitted to the measured S(h) profile using three free parameters. At altitudes just above the F2 layer peak height hmF2, the shape function S1 controls S(h), and at greater altitudes S2 controls S(h). The height of the intersection of S1 and S2 is defined as the transition height h(sub T) indicating the transition from an O(+) to an H(+)-dominated profile shape. The observed transition heights range from approx.500 km to 800 km.

Generalized Models for Rock Joint Surface Shapes

PubMed Central

Du, Shigui; Hu, Yunjin; Hu, Xiaofei

2014-01-01

Generalized models of joint surface shapes are the foundation for mechanism studies on the mechanical effects of rock joint surface shapes. Based on extensive field investigations of rock joint surface shapes, generalized models for three level shapes named macroscopic outline, surface undulating shape, and microcosmic roughness were established through statistical analyses of 20,078 rock joint surface profiles. The relative amplitude of profile curves was used as a borderline for the division of different level shapes. The study results show that the macroscopic outline has three basic features such as planar, arc-shaped, and stepped; the surface undulating shape has three basic features such as planar, undulating, and stepped; and the microcosmic roughness has two basic features such as smooth and rough. PMID:25152901

Generation of an ultra-flexible focused top-hat beam profile with aspheres

NASA Astrophysics Data System (ADS)

Möhl, A.; Wickenhagen, S.; Fuchs, U.

2017-02-01

The demand for a uniform intensity distribution in the focal region of the working beam is growing steadily, especially in the field of laser material processing. To generate such a top-hat beam profile, it was shown in the past, that the use of refractive beam shaping solutions provides very good results. In this work, existing beam shaping knowledge is combined with an intelligent modular approach to create a new beam shaping solution, that simplifies both, handling and integration into existing set-ups. Furthermore, the present system enables not just a flattop intensity distribution, but even donut shaped beam profile without adding any further components to the system. Additionally, this beam shaping system is built and successfully tested. Some results of the characterization are presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gitti, Myriam; Nulsen, Paul E. J.; David, Laurence P.

We present the results of a Chandra study of the Hydra A galaxy cluster, where a powerful active galactic nucleus (AGN) outburst created a large-scale cocoon shock. We investigated possible azimuthal variations in shock strength and shape, finding indications for a weak shock with a Mach number in the range {approx}1.2-1.3. We measured the temperature change across the shock front. However, the detection of a temperature rise in the regions immediately inside of the front is complicated by the underlying temperature profile of the cluster atmosphere. We measured the global temperature profile of the cluster up to 700 kpc, whichmore » represents the farthest measurement obtained with Chandra for this cluster. A 'plateau' in the temperature profile in the range {approx}70-150 kpc indicates the presence of cool gas, which is likely the result of uplift of material by the AGN outburst. After masking the cool filaments visible in the hardness ratio map, the plateau disappears and the temperature profile recovers a typical shape with a peak around 190 kpc, just inside the shock front. However, it is unlikely that such a temperature feature is produced by the shock as it is consistent with the general shape of the temperature profiles observed for relaxed galaxy clusters. We studied the spectral properties of the cool filaments finding evidence that {approx}10{sup 11} M{sub sun} of low-entropy material has been dredged up by the rising lobes from the central 30 kpc to the observed current position of 75-150 kpc. The energy required to lift the cool gas is {approx}> 2.2 x 10{sup 60} erg, which is comparable to the work required to inflate the cavities and is {approx}25% of the total energy of the large-scale shock. Our results show that the AGN feedback in Hydra A is acting not only by directly heating the gas, but also by removing a substantial amount of potential fuel for the supermassive black hole.« less

Spectroscopic investigation of the high-current phase of a pulsed GMAW process

NASA Astrophysics Data System (ADS)

Rouffet, M. E.; Wendt, M.; Goett, G.; Kozakov, R.; Schoepp, H.; Weltmann, K. D.; Uhrlandt, D.

2010-11-01

While metal vapours have an important impact on the efficiency of the pulsed gas metal arc welding process, only a few papers are focused on this effect. In this paper, methods based on emission spectroscopy are performed to improve the understanding of the physical phenomena occurring during the high-current pulse. Boltzmann plots applied to iron lines, the Stark broadening of the 696.5 nm argon line and composition calculations assuming local thermodynamic equilibrium are used to determine characteristic parameters of the plasma. It is observed that the central part of the arc is composed mainly of iron. The percentage of iron increases quickly at the beginning of the high-current pulse, and slowly decreases when the central part broadens. During the high-current phase the temperature profile has a minimum value of around 8000 K at the axis of the arc while the argon envelope of the central part reaches temperatures of approximately 13.000 K. The high percentage of iron and the high radiation of the plasma at the centre can explain the measured shape of the temperature profile.

Serial profiles of electrostatic potential in five New Mexico thunderstorms

NASA Astrophysics Data System (ADS)

Stolzenburg, Maribeth; Marshall, Thomas C.

2008-07-01

Profiles of electric potential (V) integrated from balloon-borne electric field (E) measurements are used to investigate the electrical evolution of thunderstorms over the mountains in central New Mexico. With sequential soundings through multiple storms, the time skew associated with obtaining V from a noninstantaneous sounding is also studied. The data show that a basic V profile, with a maximum above a minimum, forms in the early stage of the storm and is maintained throughout its mature stage. Series of soundings from individual storms show only a gradual evolution in the V profile from the early through the mature stage, as the extrema descend in altitude and become shallower and vertically closer together. More evolution occurs in the late stage, when the shape of the V profile reverses to have a minimum above a maximum. The 17 V(z) profiles from the mature stage of five different storms are also very similar in overall shape, suggesting that the basic shape is not significantly affected by differences in lightning flash rate among these storms. The findings indicate that the potential profile during a typical sounding in the mature stage is relatively stable, and the overall shape of the mature stage V profile does not change markedly on the time scale of a particular balloon sounding (10-30 min) through New Mexico mountain storms. Thus time-skew problems in the V profiles are minor during a storm's mature stage.

Yet one more dwell time algorithm

NASA Astrophysics Data System (ADS)

Haberl, Alexander; Rascher, Rolf

2017-06-01

The current demand of even more powerful and efficient microprocessors, for e.g. deep learning, has led to an ongoing trend of reducing the feature size of the integrated circuits. These processors are patterned with EUV-lithography which enables 7 nm chips [1]. To produce mirrors which satisfy the needed requirements is a challenging task. Not only increasing requirements on the imaging properties, but also new lens shapes, such as aspheres or lenses with free-form surfaces, require innovative production processes. However, these lenses need new deterministic sub-aperture polishing methods that have been established in the past few years. These polishing methods are characterized, by an empirically determined TIF and local stock removal. Such a deterministic polishing method is ion-beam-figuring (IBF). The beam profile of an ion beam is adjusted to a nearly ideal Gaussian shape by various parameters. With the known removal function, a dwell time profile can be generated for each measured error profile. Such a profile is always generated pixel-accurately to the predetermined error profile, with the aim always of minimizing the existing surface structures up to the cut-off frequency of the tool used [2]. The processing success of a correction-polishing run depends decisively on the accuracy of the previously computed dwell-time profile. So the used algorithm to calculate the dwell time has to accurately reflect the reality. But furthermore the machine operator should have no influence on the dwell-time calculation. Conclusively there mustn't be any parameters which have an influence on the calculation result. And lastly it should take a minimum of machining time to get a minimum of remaining error structures. Unfortunately current dwell time algorithm calculations are divergent, user-dependent, tending to create high processing times and need several parameters to bet set. This paper describes an, realistic, convergent and user independent dwell time algorithm. The typical processing times are reduced to about 80 % up to 50 % compared to conventional algorithms (Lucy-Richardson, Van-Cittert …) as used in established machines. To verify its effectiveness a plane surface was machined on an IBF.

Nanofabrication of 10-nm T-shaped gates using a double patterning process with electron beam lithography and dry etch

NASA Astrophysics Data System (ADS)

Shao, Jinhai; Deng, Jianan; Lu, W.; Chen, Yifang

2017-07-01

A process to fabricate T-shaped gates with the footprint scaling down to 10 nm using a double patterning procedure is reported. One of the keys in this process is to separate the definition of the footprint from that for the gate-head so that the proximity effect originated from electron forward scattering in the resist is significantly minimized, enabling us to achieve as narrow as 10-nm foot width. Furthermore, in contrast to the reported technique for 10-nm T-shaped profile in resist, this process utilizes a metallic film with a nanoslit as an etch mask to form a well-defined 10-nm-wide foot in a SiNx layer by reactive ion etch. Such a double patterning process has demonstrated enhanced reliability. The detailed process is comprehensively described, and its advantages and limitations are discussed. Nanofabrication of InP-based high-electron-mobility transistors using the developed process for 10- to 20-nm T-shaped gates is currently under the way.

Three dimensional shape measurement of wear particle by iterative volume intersection

NASA Astrophysics Data System (ADS)

Wu, Hongkun; Li, Ruowei; Liu, Shilong; Rahman, Md Arifur; Liu, Sanchi; Kwok, Ngaiming; Peng, Zhongxiao

2018-04-01

The morphology of wear particle is a fundamental indicator where wear oriented machine health can be assessed. Previous research proved that thorough measurement of the particle shape allows more reliable explanation of the occurred wear mechanism. However, most of current particle measurement techniques are focused on extraction of the two-dimensional (2-D) morphology, while other critical particle features including volume and thickness are not available. As a result, a three-dimensional (3-D) shape measurement method is developed to enable a more comprehensive particle feature description. The developed method is implemented in three steps: (1) particle profiles in multiple views are captured via a camera mounted above a micro fluid channel; (2) a preliminary reconstruction is accomplished by the shape-from-silhouette approach with the collected particle contours; (3) an iterative re-projection process follows to obtain the final 3-D measurement by minimizing the difference between the original and the re-projected contours. Results from real data are presented, demonstrating the feasibility of the proposed method.

Resistivity and Seismic Surface Wave Tomography Results for the Nevşehir Kale Region: Cappadocia, Turkey

NASA Astrophysics Data System (ADS)

Coşkun, Nart; Çakır, Özcan; Erduran, Murat; Arif Kutlu, Yusuf

2014-05-01

The Nevşehir Kale region located in the middle of Cappadocia with approximately cone shape is investigated for existence of an underground city using the geophysical methods of electrical resistivity and seismic surface wave tomography together. Underground cities are generally known to exist in Cappadocia. The current study has obtained important clues that there may be another one under the Nevşehir Kale region. Two-dimensional resistivity and seismic profiles approximately 4-km long surrounding the Nevşehir Kale are measured to determine the distribution of electrical resistivities and seismic velocities under the profiles. Several high resistivity anomalies with a depth range 8-20 m are discovered to associate with a systematic void structure beneath the region. Because of the high resolution resistivity measurement system currently employed we were able to isolate the void structure from the embedding structure. Low seismic velocity zones associated with the high resistivity depths are also discovered. Using three-dimensional visualization techniques we show the extension of the void structure under the measured profiles.

An iterative algorithm for determining depth profiles of collection probability by electron-beam-induced current

NASA Astrophysics Data System (ADS)

Konovalov, Igor; Breitenstein, Otwin

2001-01-01

An iterative algorithm for the derivation of depth profiles of the minority carrier collection probability in a semiconductor with or without a coating on the top is presented using energy-resolved electron-beam-induced current measurements in planar geometry. The calculation is based on the depth-dose function of Everhart and Hoff (Everhart T E and Hoff P H 1971 J. Appl. Phys. 42 5837) and on the penetration-range function of Kanaya and Okayama (Kanaya K and Okayama S 1972 J. Phys. D: Appl. Phys. 5 43) or on that of Fitting (Fitting H-J 1974 Phys. Status Solidi/ a 26 525). It can also be performed with any other depth-dose functions. Using this algorithm does not require us to make any assumptions on the shape of the collection profile within the depth of interest. The influence of an absorbing top contact and/or a limited thickness of the semiconductor layer appear in the result, but can also be taken explicitly into account. Examples using silicon and CIS solar cells as well as a GaAs LED are presented.

Selective 2′-hydroxyl acylation analyzed by primer extension and mutational profiling (SHAPE-MaP) for direct, versatile, and accurate RNA structure analysis

PubMed Central

Smola, Matthew J.; Rice, Greggory M.; Busan, Steven; Siegfried, Nathan A.; Weeks, Kevin M.

2016-01-01

SHAPE chemistries exploit small electrophilic reagents that react with the 2′-hydroxyl group to interrogate RNA structure at single-nucleotide resolution. Mutational profiling (MaP) identifies modified residues based on the ability of reverse transcriptase to misread a SHAPE-modified nucleotide and then counting the resulting mutations by massively parallel sequencing. The SHAPE-MaP approach measures the structure of large and transcriptome-wide systems as accurately as for simple model RNAs. This protocol describes the experimental steps, implemented over three days, required to perform SHAPE probing and construct multiplexed SHAPE-MaP libraries suitable for deep sequencing. These steps include RNA folding and SHAPE structure probing, mutational profiling by reverse transcription, library construction, and sequencing. Automated processing of MaP sequencing data is accomplished using two software packages. ShapeMapper converts raw sequencing files into mutational profiles, creates SHAPE reactivity plots, and provides useful troubleshooting information, often within an hour. SuperFold uses these data to model RNA secondary structures, identify regions with well-defined structures, and visualize probable and alternative helices, often in under a day. We illustrate these algorithms with the E. coli thiamine pyrophosphate riboswitch, E. coli 16S rRNA, and HIV-1 genomic RNAs. SHAPE-MaP can be used to make nucleotide-resolution biophysical measurements of individual RNA motifs, rare components of complex RNA ensembles, and entire transcriptomes. The straightforward MaP strategy greatly expands the number, length, and complexity of analyzable RNA structures. PMID:26426499

On the avalanche generation of runaway electrons during tokamak disruptions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martín-Solís, J. R., E-mail: solis@fis.uc3m.es; Loarte, A.; Lehnen, M.

2015-08-15

A simple zero dimensional model for a tokamak disruption is developed to evaluate the avalanche multiplication of a runaway primary seed during the current quench phase of a fast disruptive event. Analytical expressions for the plateau runaway current, the energy of the runaway beam, and the runaway energy distribution function are obtained allowing the identification of the parameters dominating the formation of the runaway current during disruptions. The effect of the electromagnetic coupling to the vessel and the penetration of the external magnetic energy during the disruption current quench as well as of the collisional dissipation of the runaway currentmore » at high densities are investigated. Current profile shape effects during the formation of the runaway beam are also addressed by means of an upgraded one-dimensional model.« less

Selective 2'-hydroxyl acylation analyzed by primer extension and mutational profiling (SHAPE-MaP) for direct, versatile and accurate RNA structure analysis.

PubMed

Smola, Matthew J; Rice, Greggory M; Busan, Steven; Siegfried, Nathan A; Weeks, Kevin M

2015-11-01

Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) chemistries exploit small electrophilic reagents that react with 2'-hydroxyl groups to interrogate RNA structure at single-nucleotide resolution. Mutational profiling (MaP) identifies modified residues by using reverse transcriptase to misread a SHAPE-modified nucleotide and then counting the resulting mutations by massively parallel sequencing. The SHAPE-MaP approach measures the structure of large and transcriptome-wide systems as accurately as can be done for simple model RNAs. This protocol describes the experimental steps, implemented over 3 d, that are required to perform SHAPE probing and to construct multiplexed SHAPE-MaP libraries suitable for deep sequencing. Automated processing of MaP sequencing data is accomplished using two software packages. ShapeMapper converts raw sequencing files into mutational profiles, creates SHAPE reactivity plots and provides useful troubleshooting information. SuperFold uses these data to model RNA secondary structures, identify regions with well-defined structures and visualize probable and alternative helices, often in under 1 d. SHAPE-MaP can be used to make nucleotide-resolution biophysical measurements of individual RNA motifs, rare components of complex RNA ensembles and entire transcriptomes.

Differential sensitization of parenting on early adolescent cortisol: Moderation by profiles of maternal stress.

PubMed

Martin, Christina Gamache; Kim, Hyoun K; Fisher, Philip A

2016-05-01

The hypothalamic-pituitary-adrenal (HPA) axis is a critical component of the body's stress-response neurobiological system, and its development and functioning are shaped by the social environment. Much of our understanding of the effects of the caregiving environment on the HPA axis is based on (a) parenting in young children and (b) individual maternal stressors, such as depression. Yet, less is known about how parenting behaviors and maternal stressors interact to influence child cortisol regulation, particularly in older children. With an ethnically diverse sample of 199 mothers and their early adolescent children (M=11.00years; 54% female), a profile analytic approach was used to investigate how multiple phenotypes of maternal stress co-occur and moderate the relation between parenting behaviors and youths' diurnal cortisol rhythms. Latent profile analysis yielded 4 profiles: current parenting stress, concurrent parenting and childhood stress, childhood stress, and low stress. For mothers with the concurrent parenting and childhood stress profile, inconsistent discipline, poor parental supervision, and harsh caregiving behaviors each were related to flattened diurnal cortisol rhythms in their adolescents. For mothers with the current parenting stress and childhood stress profiles, their use of inconsistent discipline was associated with flattened diurnal cortisol rhythms in their adolescents. For mothers with the low stress profile, none of the parenting behaviors was related to their adolescents' cortisol regulation. Findings suggest that based on mothers' stress profile, parenting behaviors are differentially related to youths' diurnal cortisol rhythms. Implications for parenting interventions are discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Shape-designed single-polymer micelles: a proof-of-concept simulation

NASA Astrophysics Data System (ADS)

Moths, Brian; Witten, Thomas A.

Much effort has been directed towards self-assembling nanostructures. Strong, local interactions between specific building blocks often determine these structures (e.g., globular proteins). We seek to produce designed structures that are instead determined by collective effects of weak interactions (e.g., surfactant self-assembly). Such structures may reversibly change conformation or disassemble in response to changing solvent conditions, and, being soft, have potential to adapt to fluctuating or unknown application-imposed shape requirements. Concretely, we aim to realize such a structure in the form of a single polymer micelle--an amphiphilic polymer exhibiting a condensed, phase-segregated conformation when immersed in solvent. Connecting all amphiphiles into a single chain provides geometric constraints controlling the surface curvature profile, thus dictating a non-trivial shape. We present 2D Monte Carlo simulation results demonstrating the feasibility of such soft, shape-designed micelles. Preliminary results demonstrate a stable concave ``dimple'' in a micelle composed of a single A-B multiblock linear copolymer. We discuss both current limitations on shape robustness and effects of block asymmetry, block molecular weights and overall chain length on micelle shape. This work was supported in part by the National Science Foundation's MRSEC Program under Award Number DMR-1420709.

Turbulent slurry flow measurement using ultrasonic Doppler method in rectangular pipe

NASA Astrophysics Data System (ADS)

Bareš, V.; Krupička, J.; Picek, T.; Brabec, J.; Matoušek, V.

2014-03-01

Distribution of velocity and Reynolds stress was measured using ultrasonic velocimetry in flows of water and Newtonian water-ballotini slurries in a pressurized Plexiglas pipe. Profiles of the measured parameters were sensed in the vertical plane at the centreline of a rectangular cross section of the pipe. Reference measurements in clear water produced expected symmetrical velocity profiles the shape of which was affected by secondary currents developed in the rectangular pipe. Slurry-flow experiments provided information on an effect of the concentration of solid grains on the internal structure of the flow. Strong attenuation of velocity fluctuations caused by a presence of grains was identified. The attenuation increased with the increasing local concentration of the grains.

Fabrication of parabolic cylindrical microlens array by shaped femtosecond laser

NASA Astrophysics Data System (ADS)

Luo, Zhi; Yin, Kai; Dong, Xinran; Duan, Ji'an

2018-04-01

A simple and efficient technique for fabricating parabolic cylindrical microlens arrays (CMLAs) on the surface of fused silica by shaped femtosecond (fs) laser direct-writing is demonstrated. By means of spatially shaping of a Gaussian fs laser beam to a Bessel distribution, an inversed cylindrical shape laser intensity profile is formed in a specific cross-sectional plane among the shaped optical field. Applying it to experiments, large area close-packed parabolic CMLAs with line-width of 37.5 μm and array size of about 5 × 5 mm are produced. The cross-sectional outline of obtained lenslets has a satisfied parabolic profile and the numerical aperture (NA) of lenslets is more than 0.35. Furthermore, the focusing performance of the fabricated CMLA is also tested in this work and it has been demonstrated that the focusing power of the CMLA with a parabolic profile is better than that with a semi-circular one.

Integration of parts in the facial skeleton and cervical vertebrae.

PubMed

McCane, Brendan; Kean, Martin R

2011-01-01

The purpose of this study was to undertake an exploratory analysis of the relationship among parts in the facial skeleton and cervical vertebrae and their integration as 2-dimensional shapes by determining their individual variations and covariations. The study was motivated by considerations applicable to clinical orthodontics and maxillofacial surgery, in which such relationships bear directly on pretreatment analysis and assessment of posttreatment outcome. Lateral radiographs of 61 adolescents of both sexes without major malocclusions were digitized and marked up by using continuous outline spline curves for 8 defined parts in the facial skeleton, including the cervical vertebrae. Individual part variation was analyzed by using principal components analysis, and paired part covariation was analyzed by using 2-block partial least squares analysis in 2 modes: relative size, position, and shape; and shape only. For individual part variations, cranial base, soft-tissue profile, and mandible had the largest variations across the sample. For covariation of relative size, position, and shape, the cervical vertebrae were highly correlated with the cranial base (r = 0.80), nasomaxillary complex (r = 0.70), mandible (r = 0.74), maxillary dentition (r = 0.70), and mandibular dentition (r = 0.74); the maxillary dentition and mandibular dentition were highly correlated (r = 0.70); the mandible was highly correlated with the bony profile (r = 0.72), soft-tissue profile (r = 0.79), and, to a lesser extent, the cranial base (r = 0.67); the bony profile was highly correlated with the cranial base (r = 0.70) and soft-tissue profile (r = 0.80); the soft-tissue profile was highly correlated with the nasomaxillary dentition (r = 0.81). Covariation of shape only was much weaker with significant covariations found between bony profile and mandible (r = 0.53), bony profile and mandibular dentition (r = 0.65), mandibular dentition and soft-tissue profile (r = 0.54), mandibular dentition and maxillary dentition (r = 0.55), and bony profile and soft-tissue profile (r = 0.69). We found that integration of the shape of parts in the facial skeleton and cervical vertebrae is weak; it is the relative size, position, and orientation of parts that form the strongest correlations. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Overview of progesterone profiles in dairy cows.

PubMed

Blavy, P; Derks, M; Martin, O; Höglund, J K; Friggens, N C

2016-09-01

The aim of this study was to gain a better understanding of the variability in shape and features of all progesterone profiles during estrus cycles in cows and to create templates for cycle shapes and features as a base for further research. Milk progesterone data from 1418 estrus cycles, coming from 1009 lactations, was obtained from the Danish Cattle Research Centre in Foulum, Denmark. Milk samples were analyzed daily using a Ridgeway ELISA-kit. Estrus cycles with less than 10 data points or shorter than 4 days were discarded, after which 1006 cycles remained in the analysis. A median kernel of three data points was used to smooth the progesterone time series. The time between start of progesterone rise and end of progesterone decline was identified by fitting a simple model consisting of base length and a quadratic curve to progesterone data, and this luteal-like phase (LLP) was used for further analysis. The data set of 1006 LLP's was divided into five quantiles based on length. Within quantiles, a cluster analysis was performed on the basis of shape distance. Height, upward and downward slope, and progesterone level on Day 5 were compared between quantiles. Also, the ratio of typical versus atypical shapes was described, using a reference curve on the basis of data in Q1-Q4. The main results of this article were that (1) most of the progesterone profiles showed a typical profile, including the ones that exceeded the optimum cycle length of 24 days; (2) cycles in Q2 and Q3 had steeper slopes and higher peak progesterone levels than cycles in Q1 and Q4 but, when normalized, had a similar shape. Results were used to define differences between quantiles that can be used as templates. Compared to Q1, LLP's in Q2 had a shape that is 1.068 times steeper and 1.048 times higher. Luteal-like phases in Q3 were 1.053 times steeper and 1.018 times higher. Luteal-like phases in Q4 were 0.977 times steeper and 0.973 times higher than LLP's in Q1. This article adds to our knowledge about the variability of progesterone profiles and their shape differences. The profile clustering procedure described in this article can be used as a means to classify progesterone profiles without recourse to an a priori set of rules, which arbitrarily segment the natural variability in these profiles. Using data-derived profile shapes may allow a more accurate assessment of the effects of, e.g., nutritional management or breeding system on progesterone profiles. Copyright © 2016 Elsevier Inc. All rights reserved.

Profile Optimization Method for Robust Airfoil Shape Optimization in Viscous Flow

NASA Technical Reports Server (NTRS)

Li, Wu

2003-01-01

Simulation results obtained by using FUN2D for robust airfoil shape optimization in transonic viscous flow are included to show the potential of the profile optimization method for generating fairly smooth optimal airfoils with no off-design performance degradation.

Understanding the stability of the low torque ITER Baseline Scenario in DIII-D

NASA Astrophysics Data System (ADS)

Turco, Francesca

2017-10-01

Analysis of the evolving current density (J), pedestal and rotation profiles in a database of 200 ITER Baseline Scenario discharges in the DIII-D tokamak sheds light on the cause of the disruptive instability limiting both high and low torque operation of these plasmas. The m =2/n =1 tearing modes, occurring after several pressure-relaxation times, are related to the shape of the current profile in the outer region of the plasma. The q =2 surface is located just inside the current pedestal, near a minimum in J. This well in J deepens at constant betaN and at lower rotation, causing the equilibrium to evolve towards a classically unstable state. Lack of core-edge differential rotation likely biases the marginal point towards instability during the secular trend in J. New results from the 2017 experimental campaign establish the first reproducible, stable operation at T =0 Nm for this scenario. A new ramp-up recipe with delayed heating keeps the discharges stable without the need for ECCD stabilization. The J profile shape in the new shots is consistent with an expansion of the previous ``shallow well'' stable operational space. Realtime Active MHD Spectroscopy (AMS) has been applied to IBS plasmas for the first time, and the plasma response measurements show that the AMS can help sense the approach to instability during the discharges. The AMS data shows the trend towards instability at low rotation, and MARS-K modelling partially reproduces the experimental trend if collisionality and resistivity are included. The modelling results are sensitive to the edge resistivity, and this can indicate that the AMS is measuring the changes in ideal (kink) stability, to which the tearing stability index delta' is correlated. Together these results constitute a crucial step to acquire physical understanding and sensing capability for the MHD stability in the Q =10 ITER scenario. Work supported by US DOE under DE-FC02-04ER54698 and DE-FG02-04ER54761.

Fast and efficient STT switching in MTJ using additional transient pulse current

NASA Astrophysics Data System (ADS)

Pathak, Sachin; Cha, Jongin; Jo, Kangwook; Yoon, Hongil; Hong, Jongill

2017-06-01

We propose a profile of write pulse current-density to switch magnetization in a perpendicular magnetic tunnel junction to reduce switching time and write energy as well. Our simulated results show that an overshoot transient pulse current-density (current spike) imposed to conventional rectangular-shaped pulse current-density (main pulse) significantly improves switching speed that yields the reduction in write energy accordingly. For example, we could dramatically reduce the switching time by 80% and thereby reduce the write energy over 9% in comparison to the switching without current spike. The current spike affects the spin dynamics of the free layer and reduces the switching time mainly due to spin torque induced. On the other hand, the large Oersted field induced causes changes in spin texture. We believe our proposed write scheme can make a breakthrough in magnetic random access memory technology seeking both high speed operation and low energy consumption.

Direct measurements of safety factor profiles with motional Stark effect for KSTAR tokamak discharges with internal transport barriers

NASA Astrophysics Data System (ADS)

Ko, J.; Chung, J.

2017-06-01

The safety factor profile evolutions have been measured from the plasma discharges with the external current drive mechanism such as the multi-ion-source neutral beam injection for the Korea Superconducting Tokamak Advanced Research (KSTAR) for the first time. This measurement has been possible by the newly installed motional Stark effect (MSE) diagnostic system that utilizes the polarized Balmer-alpha emission from the energetic neutral deuterium atoms induced by the Stark effect under the Lorentz electric field. The 25-channel KSTAR MSE diagnostic is based on the conventional photoelastic modulator approach with the spatial and temporal resolutions less than 2 cm (for the most of the channels except 2 to 3 channels inside the magnetic axis) and about 10 ms, respectively. The strong Faraday rotation imposed on the optical elements in the diagnostic system is calibrated out from a separate and well-designed polarization measurement procedure using an in-vessel reference polarizer during the toroidal-field ramp-up phase before the plasma experiment starts. The combination of the non-inductive current drive during the ramp-up and shape control enables the formation of the internal transport barrier where the pitch angle profiles indicate flat or slightly hollow profiles in the safety factor.

A Critical Fast Ion Beta in the Madison Symmetric Torus Reversed Field Pinch

NASA Astrophysics Data System (ADS)

Capecchi, William J.

The first fast-ion profile measurements have been made in a reversed-field pinch (RFP) plasma. A large population of fast-ions are deposited in the core of the Madison Symmetric Torus (MST) through use of a 1 MW neutral beam injector (NBI) giving rise to a variety of beam-driven instabilities. One such mode, the energetic-particle mode (EPM) has been shown to reduce fast-ion content in MST, evident through drops in signal levels of the advanced neutral particle analyzer (ANPA). EPMs in MST appear as bursts of magnetic fluctuations at a lab frequency of ˜100 kHz reaching peak amplitude and decaying away within 100 microseconds. A burst ensemble of the neutron data does not reveal a drop in neutron emission across a burst, implying the population of fast-ions transported by a burst constitute a small fraction of the total. The burst may also pitch-angle scatter out of the ANPA phase space or be transported to mid-radius where charge-exchange with the background neutrals or fast-ion orbit stochasticity may reduce fast-ion confinement. Data gathered from the expanded neutron diagnostic suite including a new collimated neutron detector (CiNDe) was used to reconstruct the fast-ion profile in MST and measure critical fast-ion beta quantities. Measurements were made in plasma conditions with varying magnetic field strength in order to investigate the interplay between the energetic particle (EP) drive and Alfven continuum damping. The measured values of the core fast-ion beta (7.5% (1.2%) in 300 (500) kA plasmas) are reduced from classical predictions (TRANSP predicts up to 10% core value) due to EPM activity. The frequency, magnitude, and rate of occurrence of the bursts depends on the tearing mode amplitude, Alfven continuum damping rate, fast-ion profile shape, and resonant orbit dynamics. Marginal stability was reached in both moderate- (300 kA) and high- (500 kA) current discharges, marked by sustained EPM activity and a saturated global neutron signal during NBI. The difference in profile shape is interpreted to be related to the core-most resonant tearing mode amplitude, as a larger core magnetic island moves the location of steepest fast-ion gradient further out in radius, resulting in lower confinement of the fast-ions. The reconstructed profile is more strongly peaked at lower current, consistent with a lower measured core-most tearing mode amplitude. A larger dataset at lower current gives enough temporal resolution to investigate the evolution of the fast-ion profile. The suppression of the core-most tearing mode amplitude during NBI results in a rapid and dynamically evolving fast-ion profile at the beginning of the NBI discharge and results in an initially broader profile early evolving into a more strongly peaked profile later in the NBI discharge.

Constant- q data representation in Neutron Compton scattering on the VESUVIO spectrometer

NASA Astrophysics Data System (ADS)

Senesi, R.; Pietropaolo, A.; Andreani, C.

2008-09-01

Standard data analysis on the VESUVIO spectrometer at ISIS is carried out within the Impulse Approximation framework, making use of the West scaling variable y. The experiments are performed using the time-of-flight technique with the detectors positioned at constant scattering angles. Line shape analysis is routinely performed in the y-scaling framework, using two different (and equivalent) approaches: (1) fitting the parameters of the recoil peaks directly to fixed-angle time-of-flight spectra; (2) transforming the time-of-flight spectra into fixed-angle y spectra, referred to as the Neutron Compton Profiles, and then fitting the line shape parameters. The present work shows that scattering signals from different fixed-angle detectors can be collected and rebinned to obtain Neutron Compton Profiles at constant wave vector transfer, q, allowing for a suitable interpretation of data in terms of the dynamical structure factor, S(q,ω). The current limits of applicability of such a procedure are discussed in terms of the available q-range and relative uncertainties for the VESUVIO experimental set up and of the main approximations involved.

Profiling charge complementarity and selectivity for binding at the protein surface.

PubMed

Sulea, Traian; Purisima, Enrico O

2003-05-01

A novel analysis and representation of the protein surface in terms of electrostatic binding complementarity and selectivity is presented. The charge optimization methodology is applied in a probe-based approach that simulates the binding process to the target protein. The molecular surface is color coded according to calculated optimal charge or according to charge selectivity, i.e., the binding cost of deviating from the optimal charge. The optimal charge profile depends on both the protein shape and charge distribution whereas the charge selectivity profile depends only on protein shape. High selectivity is concentrated in well-shaped concave pockets, whereas solvent-exposed convex regions are not charge selective. This suggests the synergy of charge and shape selectivity hot spots toward molecular selection and recognition, as well as the asymmetry of charge selectivity at the binding interface of biomolecular systems. The charge complementarity and selectivity profiles map relevant electrostatic properties in a readily interpretable way and encode information that is quite different from that visualized in the standard electrostatic potential map of unbound proteins.

Numerical analysis of internal solitary wave generation around a Island in Kuroshio Current using MITgcm.

NASA Astrophysics Data System (ADS)

Kodaira, Tsubasa; Waseda, Takuji

2013-04-01

We have conducted ADCP and CTD measurements from 31/8/2010 to 2/9/2010 at the Miyake Island, located approximately 180 km south of Tokyo. The Kuroshio Current approached the island in this period, and the PALSAR image showed parabolic bright line upstream of the island. This bright line may be a surface signature of large amplitude internal solitary wave. Although our measurements did not explicitly show evidence of the internal solitary wave, critical condition might have been satisfied because of the Kuroshio Current and strong seasonal thermocline. To discover the generation mechanism of the large amplitude internal solitary wave at the Miyake Island, we have conducted non-hydrostatic numerical simulation with the MITgcm. A simple box domain, with open boundaries at all sides, is used. The island is simplified to circular cylinder or Gaussian Bell whose radius is 3km at ocean surface level. The size of the domain is 40kmx40kmx500m for circular cylinder cases and 80kmx80kmx500m for Gaussian bell cases. By looking at our CTD data, we have chosen for initial and boundary conditions a tanh function for vertical temperature profile. Salinity was kept constant for simplicity. Vertical density profile is also described by tanh function because we adopt linear type of equation of state. Vertical velocity profile is constant or linearly changed with depth; the vertical mean speed corresponds to the linear phase speed of the first baroclinic mode obtained by solving the eigen-value problem. With these configurations, we have conducted two series of simulations: shear flow through cylinder and uniform flow going through Gaussian Bell topography. Internal solitary waves were generated in front of the cylinder for the first series of simulations with shear flow. The generated internal waves almost purely consisted of 1st baroclinic component. Their intensities were linearly related with upstream vertical shear strength. As the internal solitary wave became larger, its width became wider compared to the KdV solution described by Grimshaw (2002). This is predicted because higher order analytical solution for 2-layer fluids, i.e. the eKdV solution, gives broader solitary wave shape than that of the KdV solution because of the cubic nonlinear term. When we look at the surface velocity distribution, a parabolic shape corresponding to internal solitary wave is clearly seen. According to the fully nonlinear theoretical model for internal wave between two fluids having background linear shear flow profiles (Choi and Camassa1999), the shape of internal wave is influenced by the velocity shear as well. However, we could not clarify the effect of vertical shear because there is no fully nonlinear analytical solution for large amplitude internal wave in continuously stratified fluid. Second series of simulations with uniform flow going through Gaussian Bell topography show that internal solitary wave shows up from sides of the topography. This generation is similar to the one developed in lee side of sill topography by tidal flow. With broader bell topography, generated internal waves become larger. This makes sense because forcing region is wider. A horizontal shape of the internal solitary wave is not parabolic but the two bending line forms from the sides of the island. However, no solitary wave in front of the island develops. Our results imply that vertical shear profile is needed for the formation of the depression type internal solitary, and explains the parabolic bright line observed in the SAR image

Geomorphic effectiveness of long profile shape and role of inherent geological controls, Ganga River Basin, India

NASA Astrophysics Data System (ADS)

Sonam, Sonam; Jain, Vikrant

2017-04-01

River long profile is one of the fundamental geomorphic parameters which provides a platform to study interaction of geological and geomorphic processes at different time scales. Long profile shape is governed by geological processes at 10 ^ 5 - 10 ^ 6 years' time scale and it controls the modern day (10 ^ 0 - 10 ^ 1 years' time scale) fluvial processes by controlling the spatial variability of channel slope. Identification of an appropriate model for river long profile may provide a tool to analyse the quantitative relationship between basin geology, profile shape and its geomorphic effectiveness. A systematic analysis of long profiles has been carried for the Himalayan tributaries of the Ganga River basin. Long profile shape and stream power distribution pattern is derived using SRTM DEM data (90 m spatial resolution). Peak discharge data from 34 stations is used for hydrological analysis. Lithological variability and major thrusts are marked along the river long profile. The best fit of long profile is analysed for power, logarithmic and exponential function. Second order exponential function provides the best representation of long profiles. The second order exponential equation is Z = K1*exp(-β1*L) + K2*exp(-β2*L), where Z is elevation of channel long profile, L is the length, K and β are coefficients of the exponential function. K1 and K2 are the proportion of elevation change of the long profile represented by β1 (fast) and β2 (slow) decay coefficients of the river long profile. Different values of coefficients express the variability in long profile shapes and is related with the litho-tectonic variability of the study area. Channel slope of long profile is estimated taking the derivative of exponential function. Stream power distribution pattern along long profile is estimated by superimposing the discharge and long profile slope. Sensitivity analysis of stream power distribution with decay coefficients of the second order exponential equation is evaluated for a range of coefficient values. Our analysis suggests that the amplitude of stream power peak value is dependent on K1, the proportion of elevation change coming under the fast decay exponent and the location of stream power peak is dependent of the long profile decay coefficient (β1). Different long profile shapes owing to litho-tectonic variability across the Himalayas are responsible for spatial variability of stream power distribution pattern. Most of the stream power peaks lie in the Higher Himalaya. In general, eastern rivers have higher stream power in hinterland area and low stream power in the alluvial plains. This is responsible for, 1) higher erosion rate and sediment supply in hinterland of eastern rivers, 2) the incised and stable nature of channels in the western alluvial plains and 3) aggrading channels with dynamic nature in the eastern alluvial plains. Our study shows that the spatial variability of litho-units defines the coefficients of long profile function which in turn controls the position and magnitude of stream power maxima and hence the geomorphic variability in a fluvial system.

Size Matters: Penis Size and Sexual Position in Gay Porn Profiles.

PubMed

Brennan, Joseph

2018-01-01

This article combines qualitative and quantitative textual approaches to the representation of penis size and sexual position of performers in 10 of the most visited gay pornography Web sites currently in operation. Specifically, in excess of 6,900 performer profiles sourced from 10 commercial Web sites are analyzed. Textual analysis of the profile descriptions is combined with a quantitative representation of disclosed penis size and sexual position, which is presented visually by two figures. The figures confirm that these sites generally market themselves as featuring penises that are extraordinarily large and find a sample-wide correlation between smaller penis sizes (5-6.5 inches) and receptive sexual acts (bottoming), and larger (8.5-13 inches) with penetrative acts (topping). These observations are supported through the qualitative textual readings of how the performers are described on these popular sites, revealing the narratives and marketing strategies that shape the construction of popular porn brands, performers, and profitable fantasies.

On the observability of coupled dark energy with cosmic voids

NASA Astrophysics Data System (ADS)

Sutter, P. M.; Carlesi, Edoardo; Wandelt, Benjamin D.; Knebe, Alexander

2015-01-01

Taking N-body simulations with volumes and particle densities tuned to match the sloan digital sky survey DR7 spectroscopic main sample, we assess the ability of current void catalogues to distinguish a model of coupled dark matter-dark energy from Λ cold dark matter cosmology using properties of cosmic voids. Identifying voids with the VIDE toolkit, we find no statistically significant differences in the ellipticities, but find that coupling produces a population of significantly larger voids, possibly explaining the recent result of Tavasoli et al. In addition, we use the universal density profile of Hamaus et al. to quantify the relationship between coupling and density profile shape, finding that the coupling produces broader, shallower, undercompensated profiles for large voids by thinning the walls between adjacent medium-scale voids. We find that these differences are potentially measurable with existing void catalogues once effects from survey geometries and peculiar velocities are taken into account.

Elves and associated electron density changes due to cloud-to-ground and in-cloud lightning discharges

NASA Astrophysics Data System (ADS)

Marshall, R. A.; Inan, U. S.; Glukhov, V. S.

2010-04-01

A 3-D finite difference time domain model is used to simulate the lightning electromagnetic pulse (EMP) and its interaction with the lower ionosphere. Results agree with the frequently observed, doughnut-shaped optical signature of elves but show that the structure exhibits asymmetry due to the presence of Earth's ambient magnetic field. Furthermore, in-cloud (horizontal) lightning channels produce observable optical emissions without the doughnut shape and, in fact, produce a much stronger optical output for the same channel current. Electron density perturbations associated with elves are also calculated, with contributions from attachment and ionization. Results presented as a function of parameters such as magnetic field direction, dipole current orientation, altitude and amplitude, and ambient ionospheric density profile demonstrate the highly nonlinear nature of the EMP-ionosphere interaction. Ionospheric effects of a sequence of in-cloud discharges are calculated, simulating a burst of in-cloud lightning activity and resulting in large density changes in the overlying ionosphere.

Subwavelength elastic joints connecting torsional waveguides to maximize the power transmission coefficient

NASA Astrophysics Data System (ADS)

Lee, Joong Seok; Lee, Il Kyu; Seung, Hong Min; Lee, Jun Kyu; Kim, Yoon Young

2017-03-01

Joints with slowly varying tapered shapes, such as linear or exponential profiles, are known to transmit incident wave power efficiently between two waveguides with dissimilar impedances. This statement is valid only when the considered joint length is longer than the wavelengths of the incident waves. When the joint length is shorter than the wavelengths, however, appropriate shapes of such subwavelength joints for efficient power transmission have not been explored much. In this work, considering one-dimensional torsional wave motion in a cylindrical elastic waveguide system, optimal shapes or radial profiles of a subwavelength joint maximizing the power transmission coefficient are designed by a gradient-based optimization formulation. The joint is divided into a number of thin disk elements using the transfer matrix approach and optimal radii of the disks are determined by iterative shape optimization processes for several single or bands of wavenumbers. Due to the subwavelength constraint, the optimized joint profiles were found to be considerably different from the slowly varying tapered shapes. Specifically, for bands of wavenumbers, peculiar gourd-like shapes were obtained as optimal shapes to maximize the power transmission coefficient. Numerical results from the proposed optimization formulation were also experimentally realized to verify the validity of the present designs.

Torsion and bending properties of shape memory and superelastic nickel-titanium rotary instruments.

PubMed

Ninan, Elizabeth; Berzins, David W

2013-01-01

Recently introduced into the market are shape memory nickel-titanium (NiTi) rotary files. The objective of this study was to investigate the torsion and bending properties of shape memory files (CM Wire, HyFlex CM, and Phoenix Flex) and compare them with conventional (ProFile ISO and K3) and M-Wire (GT Series X and ProFile Vortex) NiTi files. Sizes 20, 30, and 40 (n = 12/size/taper) of 0.02 taper CM Wire, Phoenix Flex, K3, and ProFile ISO and 0.04 taper HyFlex CM, ProFile ISO, GT Series X, and Vortex were tested in torsion and bending per ISO 3630-1 guidelines by using a torsiometer. All data were statistically analyzed by analysis of variance and the Tukey-Kramer test (P = .05) to determine any significant differences between the files. Significant interactions were present among factors of size and file. Variability in maximum torque values was noted among the shape memory files brands, sometimes exhibiting the greatest or least torque depending on brand, size, and taper. In general, the shape memory files showed a high angle of rotation before fracture but were not statistically different from some of the other files. However, the shape memory files were more flexible, as evidenced by significantly lower bending moments (P < .008). Shape memory files show greater flexibility compared with several other NiTi rotary file brands. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Recommended Isolated-Line Profile for Representing High-Resolution Spectroscoscopic Transitions

NASA Astrophysics Data System (ADS)

Tennyson, J.; Bernath, P. F.; Campargue, A.; Császár, A. G.; Daumont, L.; Gamache, R. R.; Hodges, J. T.; Lisak, D.; Naumenko, O. V.; Rothman, L. S.; Tran, H.; Hartmann, J.-M.; Zobov, N. F.; Buldyreva, J.; Boone, C. D.; De Vizia, M. Domenica; Gianfrani, L.; McPheat, R.; Weidmann, D.; Murray, J.; Ngo, N. H.; Polyansky, O. L.

2014-06-01

Recommendations of an IUPAC Task Group, formed in 2011 on "Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory" (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules are presented. The well-documented inadequacies of the Voigt profile, used almost universally by databases and radiative-transfer codes to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule, have resulted in the development of a variety of alternative line profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially-Correlated quadratic-Speed-Dependent Hard-Collision profile should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann-Tran profile (HTP). This profile is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions. For further details see: J. Tennyson et al, Pure Appl. Chem., 2014, in press.

SU-F-T-158: Experimental Characterization of Field Size Dependence of Dose and Lateral Beam Profiles of Scanning Proton and Carbon Ion Beams for Empirical Model in Air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y; Hsi, W; Zhao, J

2016-06-15

Purpose: The Gaussian model for the lateral profiles in air is crucial for an accurate treatment planning system. The field size dependence of dose and the lateral beam profiles of scanning proton and carbon ion beams are due mainly to particles undergoing multiple Coulomb scattering in the beam line components and secondary particles produced by nuclear interactions in the target, both of which depend upon the energy and species of the beam. In this work, lateral profile shape parameters were fitted to measurements of field size dependence dose at the center of field size in air. Methods: Previous studies havemore » employed empirical fits to measured profile data to significantly reduce the QA time required for measurements. From this approach to derive the weight and sigma of lateral profiles in air, empirical model formulations were simulated for three selected energies for both proton and carbon beams. Results: The 20%–80% lateral penumbras predicted by the double model for proton and single model for carbon with the error functions agreed with the measurements within 1 mm. The standard deviation between measured and fitted field size dependence of dose for empirical model in air has a maximum accuracy of 0.74% for proton with double Gaussian, and of 0.57% for carbon with single Gaussian. Conclusion: We have demonstrated that the double Gaussian model of lateral beam profiles is significantly better than the single Gaussian model for proton while a single Gaussian model is sufficient for carbon. The empirical equation may be used to double check the separately obtained model that is currently used by the planning system. The empirical model in air for dose of spot scanning proton and carbon ion beams cannot be directly used for irregular shaped patient fields, but can be to provide reference values for clinical use and quality assurance.« less

Modélisation morphodynamique cross-shore d'un estran vaseux

NASA Astrophysics Data System (ADS)

Waeles, Benoı̂t; Le Hir, Pierre; Silva Jacinto, Ricardo

2004-08-01

Numerical experiments were performed to simulate the profile evolution of an intertidal mudflat with a 1D cross-shore morphodynamical model. First, the hydrodynamical forcing is a cross-shore tidal current due to semi-diurnal variations of the free surface elevation at the open boundary. Further, considering the conservation of the action density of surface gravity waves, a wave height (and resulting bottom shear stress) calculation is added to the morphodynamical model. Results of the numerical experiments show that the shape of the profile reaches equilibrium. The mudflat progrades continually when the forcing is tide only, whereas it can be steady under the simultaneous action of tide and waves. To cite this article: B. Waeles et al., C. R. Geoscience 336 (2004).

Microbial community dynamics in soil aggregates shape biogeochemical gas fluxes from soil profiles - upscaling an aggregate biophysical model.

PubMed

Ebrahimi, Ali; Or, Dani

2016-09-01

Microbial communities inhabiting soil aggregates dynamically adjust their activity and composition in response to variations in hydration and other external conditions. These rapid dynamics shape signatures of biogeochemical activity and gas fluxes emitted from soil profiles. Recent mechanistic models of microbial processes in unsaturated aggregate-like pore networks revealed a highly dynamic interplay between oxic and anoxic microsites jointly shaped by hydration conditions and by aerobic and anaerobic microbial community abundance and self-organization. The spatial extent of anoxic niches (hotspots) flicker in time (hot moments) and support substantial anaerobic microbial activity even in aerated soil profiles. We employed an individual-based model for microbial community life in soil aggregate assemblies represented by 3D angular pore networks. Model aggregates of different sizes were subjected to variable water, carbon and oxygen contents that varied with soil depth as boundary conditions. The study integrates microbial activity within aggregates of different sizes and soil depth to obtain estimates of biogeochemical fluxes from the soil profile. The results quantify impacts of dynamic shifts in microbial community composition on CO2 and N2 O production rates in soil profiles in good agreement with experimental data. Aggregate size distribution and the shape of resource profiles in a soil determine how hydration dynamics shape denitrification and carbon utilization rates. Results from the mechanistic model for microbial activity in aggregates of different sizes were used to derive parameters for analytical representation of soil biogeochemical processes across large scales of practical interest for hydrological and climate models. © 2016 John Wiley & Sons Ltd.

Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach

PubMed Central

Pan, Luan; Adamchuk, Viacheslav I.; Prasher, Shiv; Gebbers, Robin; Taylor, Richard S.; Dabas, Michel

2014-01-01

Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep) soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument. PMID:25057135

Effect of Capillary Tube’s Shape on Capillary Rising Regime for Viscos Fluids

NASA Astrophysics Data System (ADS)

Soroush, F.; Moosavi, A.

2018-05-01

When properties of the displacing fluid are considered, the rising profile of the penetrating fluid in a capillary tube deviates from its classical Lucas-Washburn profile. Also, shape of capillary tube can affect the rising profile in different aspects. In this article, effect of capillary tube’s shape on the vertical capillary motion in presence of gravity is investigated by considering the properties of the displacing fluid. According to the fact that the differential equation of the capillary rising for a non-simple wall type is very difficult to solve analytically, a finite element simulation model is used for this study. After validation of the simulation model with an experiment that has been done with a simple capillary tube, shape of the capillary tube’s wall is changed in order to understand its effects on the capillary rising and different motion regimes that may appear according to different geometries. The main focus of this article is on the sinusoidal wall shapes and comparing them with a simple wall.

Equilibrium and initial linear stability analysis of liquid metal falling film flows in a varying spanwise magnetic field

NASA Astrophysics Data System (ADS)

Gao, D.; Morley, N. B.

2002-12-01

A 2D model for MHD free surface flow in a spanwise field is developed. The model, designed to simulate film flows of liquid metals in future thermo­nuclear fusion reactors, considers an applied spanwise magnetic field with spatial and temporal variation and an applied streamwise external current. A special case - a thin falling film flow in spanwise magnetic field with constant gradient and constant applied external streamwise current, is here investigated in depth to gain insight into the behavior of the MHD film flow. The fully developed flow solution is derived and initial linear stability analysis is performed for this special case. It is seen that the velocity profile is significantly changed due to the presence of the MHD effect, resulting in the free surface analog of the classic M-shape velocity profile seen in developing pipe flows in a field gradient. The field gradient is also seen to destabilize the film flow under most conditions. The effect of external current depends on the relative direction of the field gradient to the current direction. By controlling the magnitude of an external current, it is possible to obtain a linearly stable falling film under these magnetic field conditions. Tables 1, Figs 12, Refs 20.

Effect of wave-current interaction on wind-driven circulation in narrow, shallow embayments

USGS Publications Warehouse

Signell, Richard P.; Beardsley, Robert C.; Graber, H. C.; Capotondi, A.

1990-01-01

The effect of wind waves on the steady wind-driven circulation in a narrow, shallow bay is investigated with a two-dimensional (y, z) circulation model and the Grant and Madsen [1979] bottom-boundary layer model, which includes wave-current interaction. A constant wind stress is applied in the along-channel x direction to a channel with a constant cross-sectional profile h(y). The wind-induced flushing of shallow bays is shown to be sensitive to both the shape of the cross section and the effects of surface waves. The flushing increases with increasing , where h′ is the standard deviation of cross-channel depth and  is the mean depth. This is consistent with the findings of Hearn et al. [1987]. The flushing decreases, however, with the inclusion of surface wave effects which act to increase the bottom drag felt by the currents. Increasing effective bottom friction reduces the strength of the circulation, while the along-bay surface slope, bottom stress and the structure of current profiles remain nearly unchanged. An implication of the circulation dependence on wave-current interaction is that low-frequency oscillatory winds may drive a mean circulation when the wave field changes with wind direction.x

Theory of Epithelial Cell Shape Transitions Induced by Mechanoactive Chemical Gradients.

PubMed

Dasbiswas, Kinjal; Hannezo, Edouard; Gov, Nir S

2018-02-27

Cell shape is determined by a balance of intrinsic properties of the cell as well as its mechanochemical environment. Inhomogeneous shape changes underlie many morphogenetic events and involve spatial gradients in active cellular forces induced by complex chemical signaling. Here, we introduce a mechanochemical model based on the notion that cell shape changes may be induced by external diffusible biomolecules that influence cellular contractility (or equivalently, adhesions) in a concentration-dependent manner-and whose spatial profile in turn is affected by cell shape. We map out theoretically the possible interplay between chemical concentration and cellular structure. Besides providing a direct route to spatial gradients in cell shape profiles in tissues, we show that the dependence on cell shape helps create robust mechanochemical gradients. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Tailored laser beam shaping for efficient and accurate microstructuring

NASA Astrophysics Data System (ADS)

Häfner, T.; Strauß, J.; Roider, C.; Heberle, J.; Schmidt, M.

2018-02-01

Large-area processing with high material removal rates by ultrashort pulsed (USP) lasers is coming into focus by the development of high-power USP laser systems. However, currently the bottleneck for high-rate production is given by slow and inefficient beam manipulation. On the one hand, slow beam deflection with regard to high pulse repetition rates leads to heat accumulation and shielding effects, on the other hand, a conventional focus cannot provide the optimum fluence due to the Gaussian intensity profile. In this paper, we emphasize on two approaches of dynamic laser beam shaping with liquid crystal on silicon spatial light modulation and acousto-optic beam shaping. Advantages and limitations of dynamic laser beam shaping with regard to USP laser material processing and methods for reducing the influence of speckle are discussed. Additionally, the influence of optics induced aberrations on speckle characteristics is evaluated. Laser material processing results are presented correlating the achieved structure quality with the simulated and measured beam quality. Experimental and analytical investigations show a certain fluence dependence of the necessary number of alternative holograms to realize homogeneous microstructures.

Predicting turns in proteins with a unified model.

PubMed

Song, Qi; Li, Tonghua; Cong, Peisheng; Sun, Jiangming; Li, Dapeng; Tang, Shengnan

2012-01-01

Turns are a critical element of the structure of a protein; turns play a crucial role in loops, folds, and interactions. Current prediction methods are well developed for the prediction of individual turn types, including α-turn, β-turn, and γ-turn, etc. However, for further protein structure and function prediction it is necessary to develop a uniform model that can accurately predict all types of turns simultaneously. In this study, we present a novel approach, TurnP, which offers the ability to investigate all the turns in a protein based on a unified model. The main characteristics of TurnP are: (i) using newly exploited features of structural evolution information (secondary structure and shape string of protein) based on structure homologies, (ii) considering all types of turns in a unified model, and (iii) practical capability of accurate prediction of all turns simultaneously for a query. TurnP utilizes predicted secondary structures and predicted shape strings, both of which have greater accuracy, based on innovative technologies which were both developed by our group. Then, sequence and structural evolution features, which are profile of sequence, profile of secondary structures and profile of shape strings are generated by sequence and structure alignment. When TurnP was validated on a non-redundant dataset (4,107 entries) by five-fold cross-validation, we achieved an accuracy of 88.8% and a sensitivity of 71.8%, which exceeded the most state-of-the-art predictors of certain type of turn. Newly determined sequences, the EVA and CASP9 datasets were used as independent tests and the results we achieved were outstanding for turn predictions and confirmed the good performance of TurnP for practical applications.

Predicting Turns in Proteins with a Unified Model

PubMed Central

Song, Qi; Li, Tonghua; Cong, Peisheng; Sun, Jiangming; Li, Dapeng; Tang, Shengnan

2012-01-01

Motivation Turns are a critical element of the structure of a protein; turns play a crucial role in loops, folds, and interactions. Current prediction methods are well developed for the prediction of individual turn types, including α-turn, β-turn, and γ-turn, etc. However, for further protein structure and function prediction it is necessary to develop a uniform model that can accurately predict all types of turns simultaneously. Results In this study, we present a novel approach, TurnP, which offers the ability to investigate all the turns in a protein based on a unified model. The main characteristics of TurnP are: (i) using newly exploited features of structural evolution information (secondary structure and shape string of protein) based on structure homologies, (ii) considering all types of turns in a unified model, and (iii) practical capability of accurate prediction of all turns simultaneously for a query. TurnP utilizes predicted secondary structures and predicted shape strings, both of which have greater accuracy, based on innovative technologies which were both developed by our group. Then, sequence and structural evolution features, which are profile of sequence, profile of secondary structures and profile of shape strings are generated by sequence and structure alignment. When TurnP was validated on a non-redundant dataset (4,107 entries) by five-fold cross-validation, we achieved an accuracy of 88.8% and a sensitivity of 71.8%, which exceeded the most state-of-the-art predictors of certain type of turn. Newly determined sequences, the EVA and CASP9 datasets were used as independent tests and the results we achieved were outstanding for turn predictions and confirmed the good performance of TurnP for practical applications. PMID:23144872

Fused Traditional and Geometric Morphometrics Demonstrate Pinniped Whisker Diversity

PubMed Central

Ginter, Carly C.; DeWitt, Thomas J.; Fish, Frank E.; Marshall, Christopher D.

2012-01-01

Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors of vibrotactile information from the environment. Pinnipeds possess the largest vibrissae among mammals and their vibrissal hair shafts demonstrate a diversity of shapes. The vibrissae of most phocid seals exhibit a beaded morphology with repeating sequences of crests and troughs along their length. However, there are few detailed analyses of pinniped vibrissal morphology, and these are limited to a few species. Therefore, we comparatively characterized differences in vibrissal hair shaft morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods. Traditional morphometric measurements (peak-to-peak distance, crest width, trough width and total length) were collected using digital photographs. Elliptic Fourier analysis (geometric morphometrics) was used to quantify the outlines of whole vibrissae. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to their species based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. Phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Otariids split into two groups in the geometric morphometric analysis and gray seals appeared intermediate between beaded- and smooth-whiskered species in the traditional and combined analyses. Vibrissal hair shafts modulate the transduction of environmental stimuli to the mechanoreceptors in the follicle-sinus complex (F-SC), which results in vibrotactile reception, but it is currently unclear how the diversity of shapes affects environmental signal modulation. PMID:22509310

Shapes of star-gas waves in spiral galaxies

NASA Technical Reports Server (NTRS)

Lubow, Stephen H.

1988-01-01

Density-wave profile shapes are influenced by several effects. By solving viscous fluid equations, the nonlinear effects of the gas and its gravitational interaction with the stars can be analyzed. The stars are treated through a linear theory developed by Lin and coworkers. Short wavelength gravitational forces are important in determining the gas density profile shape. With the inclusion of disk finite thickness effects, the gas gravitational field remains important, but is significantly reduced at short wavelengths. Softening of the gas equation of state results in an enhanced response and a smoothing of the gas density profile. A Newtonian stress relation is marginally acceptable for HI gas clouds, but not acceptable for giant molecular clouds.

Digital holographic profilometry of the inner surface of a pipe using a current-induced wavelength change of a laser diode.

PubMed

Yokota, Masayuki; Adachi, Toru

2011-07-20

Phase-shifting digital holography is applied to the measurement of the surface profile of the inner surface of a pipe for the detection of a hole in its wall. For surface contouring of the inner wall, a two-wavelength method involving an injection-current-induced wavelength change of a laser diode is used. To illuminate and obtain information on the inner surface, a cone-shaped mirror is set inside the pipe and moved along in a longitudinal direction. The distribution of a calculated optical path length in an experimental alignment is used to compensate for the distortion due to the misalignment of the mirror in the pipe. Using the proposed method, two pieces of metal sheet pasted on the inner wall of the pipe and a hole in the wall are detected. This shows that the three-dimensional profile of a metal plate on the inner wall of a pipe can be measured using simple image processing. © 2011 Optical Society of America

The generalization of upper atmospheric wind and temperature based on the Voigt line shape profile.

PubMed

Zhang, Chunmin; He, Jian

2006-12-25

The principle of probing the upper atmospheric wind field, which is the Voigt profile spectral line shape, is presented for the first time. By the Fourier Transform of Voigt profile, with the Imaging Spectroscope and the Doppler effect of electromagnetic wave, the distribution and calculation formulae of the velocity field, temperature field, and pressure field of the upper atmosphere wind field are given. The probed source is the two major aurora emission lines originated from the metastable O(1S) and O(1D) at 557.7nm and 630.0nm. From computer simulation and error analysis, the Voigt profile, which is the correlation of the Gaussian profile and Lorentzian profile, is closest to the actual airglow emission lines.

Voigt spectral profiles in two-photon resonance fluorescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexanian, Moorad; Bose, Subir K.; Department of Physics, University of Central Florida, Orlando, Florida 32816

2007-11-15

A recent work on two-photon fluorescence is extended by considering the pump field to be a coherent state, which represents a laser field operating well above threshold. The dynamical conditions are investigated under which the two-photon spectrum gives rise, in addition to a Lorentzian line shape at the pump frequency, to two Voigt spectral sideband profiles. Additional conditions are found under which the Voigt profile behaves like either a Gaussian or a Lorentzian line shape.

Spectral shapes of rovibrational lines of CO broadened by He, Ar, Kr and SF6: A test case of the Hartmann-Tran profile

NASA Astrophysics Data System (ADS)

Ngo, N. H.; Lin, H.; Hodges, J. T.; Tran, H.

2017-12-01

High signal-to-noise ratio spectra of the (3-0) band P(1) and P(17) lines of CO broadened by He, Ar, Kr and SF6 were measured with a frequency-stabilized cavity ring-down spectroscopy system. For each collision-partner and both lines, multiple spectra were measured over pressures spanning nearly three decades up to 130 kPa. These data were analyzed with a multispectrum fitting procedure. Line shapes were modeled using the Hartmann-Tran (HT) profile with first-order line mixing as well as several other simplified profiles. The results show that for all considered collision partners (with the exception of SF6), the HT profile captures the measured line shapes with maximum absolute residuals that are within 0.1% of the peak absorption. In the case of SF6, which is the heaviest perturber investigated here, the maximum residuals for the HT profile are twice as large as for the other collision partners.

Profiling calcium signals of in vitro polarized human effector CD4+ T cells.

PubMed

Kircher, Sarah; Merino-Wong, Maylin; Niemeyer, Barbara A; Alansary, Dalia

2018-06-01

Differentiation of naïve CD4 + T cells into effector subtypes with distinct cytokine profiles and physiological roles is a tightly regulated process, the imbalance of which can lead to an inadequate immune response or autoimmune disease. The crucial role of Ca 2+ signals, mainly mediated by the store operated Ca 2+ entry (SOCE) in shaping the immune response is well described. However, it is unclear if human effector CD4 + T cell subsets show differential Ca 2+ signatures in response to different stimulation methods. Herein, we provide optimized in vitro culture conditions for polarization of human CD4 + effector T cells and characterize their SOCE following both pharmacological store depletion and direct T-cell receptor (TCR) activation. Moreover, we measured whole cell Ca 2+ release activated Ca 2+ currents (I CRAC ) and investigated whether the observed differences correlate to the expression of CRAC genes. Our results show that Ca 2+ profiles of helper CD4 + Th1, Th2 and Th17 are distinct and in part shaped by the intensity of stimulation. Regulatory T cells (Treg) are unique being the subtype with the most prominent SOCE response. Analysis of in vivo differentiated Treg unraveled the role of differential expression of ORAI2 in fine-tuning signals in Treg vs. conventional CD4 + T cells. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

Profiling Charge Complementarity and Selectivity for Binding at the Protein Surface

PubMed Central

Sulea, Traian; Purisima, Enrico O.

2003-01-01

A novel analysis and representation of the protein surface in terms of electrostatic binding complementarity and selectivity is presented. The charge optimization methodology is applied in a probe-based approach that simulates the binding process to the target protein. The molecular surface is color coded according to calculated optimal charge or according to charge selectivity, i.e., the binding cost of deviating from the optimal charge. The optimal charge profile depends on both the protein shape and charge distribution whereas the charge selectivity profile depends only on protein shape. High selectivity is concentrated in well-shaped concave pockets, whereas solvent-exposed convex regions are not charge selective. This suggests the synergy of charge and shape selectivity hot spots toward molecular selection and recognition, as well as the asymmetry of charge selectivity at the binding interface of biomolecular systems. The charge complementarity and selectivity profiles map relevant electrostatic properties in a readily interpretable way and encode information that is quite different from that visualized in the standard electrostatic potential map of unbound proteins. PMID:12719221

Diffractive beam shaping for enhanced laser polymer welding

NASA Astrophysics Data System (ADS)

Rauschenberger, J.; Vogler, D.; Raab, C.; Gubler, U.

2015-03-01

Laser welding of polymers increasingly finds application in a large number of industries such as medical technology, automotive, consumer electronics, textiles or packaging. More and more, it replaces other welding technologies for polymers, e. g. hot-plate, vibration or ultrasonic welding. At the same rate, demands on the quality of the weld, the flexibility of the production system and on processing speed have increased. Traditionally, diode lasers were employed for plastic welding with flat-top beam profiles. With the advent of fiber lasers with excellent beam quality, the possibility to modify and optimize the beam profile by beam-shaping elements has opened. Diffractive optical elements (DOE) can play a crucial role in optimizing the laser intensity profile towards the optimal M-shape beam for enhanced weld seam quality. We present results on significantly improved weld seam width constancy and enlarged process windows compared to Gaussian or flat-top beam profiles. Configurations in which the laser beam diameter and shape can be adapted and optimized without changing or aligning the laser, fiber-optic cable or optical head are shown.

Linear shaped charge

DOEpatents

Peterson, David; Stofleth, Jerome H.; Saul, Venner W.

2017-07-11

Linear shaped charges are described herein. In a general embodiment, the linear shaped charge has an explosive with an elongated arrowhead-shaped profile. The linear shaped charge also has and an elongated v-shaped liner that is inset into a recess of the explosive. Another linear shaped charge includes an explosive that is shaped as a star-shaped prism. Liners are inset into crevices of the explosive, where the explosive acts as a tamper.

Rethinking the longitudinal stream temperature paradigm: region-wide comparison of thermal infrared imagery reveals unexpected complexity of river temperatures

USGS Publications Warehouse

Fullerton, Aimee H.; Torgersen, Christian E.; Lawler, Joshua J.; Faux, Russell N.; Steel, E. Ashley; Beechie, Timothy J.; Ebersole, Joseph L.; Leibowitz, Scott J.

2015-01-01

Prevailing theory suggests that stream temperature warms asymptotically in a downstream direction, beginning at the temperature of the source in the headwaters and leveling off downstream as it converges to match meteorological conditions. However, there have been few empirical examples of longitudinal patterns of temperature in large rivers due to a paucity of data. We constructed longitudinal thermal profiles (temperature versus distance) for 53 rivers in the Pacific Northwest (USA) using an extensive dataset of remotely sensed summertime river temperatures and classified each profile into one of five patterns of downstream warming: asymptotic (increasing then flattening), linear (increasing steadily), uniform (not changing), parabolic (increasing then decreasing), or complex (not fitting other classes). We evaluated (1) how frequently profiles warmed asymptotically downstream as expected, and (2) whether relationships between river temperature and common hydroclimatic variables differed by profile class. We found considerable diversity in profile shape, with 47% of rivers warming asymptotically, and 53% having alternative profile shapes. Water temperature did not warm substantially over the course of the river for coastal parabolic and uniform profiles, and for some linear and complex profiles. Profile classes showed no clear geographical trends. The degree of correlation between river temperature and hydroclimatic variables differed among profile classes, but there was overlap among classes. Water temperature in rivers with asymptotic or parabolic profiles was positively correlated with August air temperature, tributary temperature and velocity, and negatively correlated with elevation, August precipitation, gradient, and distance upstream. Conversely, associations were less apparent in rivers with linear, uniform, or complex profiles. Factors contributing to the unique shape of parabolic profiles differed for coastal and inland rivers, where downstream cooling was influenced locally by climate or cool water inputs, respectively. Potential drivers of shape for complex profiles were specific to each river. These thermal patterns indicate diverse thermal habitats that may promote resilience of aquatic biota to climate change. Without this spatial context, climate change models may incorrectly estimate loss of thermally suitable habitat.

Mars Ozone Absorption Line Shapes from Infrared Heterodyne Spectra Applied to GCM-Predicted Ozone Profiles and to MEX/SPICAM Column Retrievals

NASA Technical Reports Server (NTRS)

Fast, Kelly E.; Kostiuk, T.; Annen, J.; Hewagama, T.; Delgado, J.; Livengood, T. A.; Lefevre, F.

2008-01-01

We present the application of infrared heterodyne line shapes of ozone on Mars to those produced by radiative transfer modeling of ozone profiles predicted by general circulation models (GCM), and to contemporaneous column abundances measured by Mars Express SPICAM. Ozone is an important tracer of photochemistry Mars' atmosphere, serving as an observable with which to test predictions of photochemistry-coupled GCMs. Infrared heterodyne spectroscopy at 9.5 microns with spectral resolving power >1,000,000 is the only technique that can directly measure fully-resolved line shapes of Martian ozone features from the surface of the Earth. Measurements were made with Goddard Space Flight Center's Heterodyne instrument for Planetary Wind And Composition (HIPWAC) at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii on February 21-24 2008 UT at Ls=35deg on or near the MEX orbital path. The HIPWAC observations were used to test GCM predictions. For example, a GCM-generated ozone profile for 60degN 112degW was scaled so that a radiative transfer calculation of its absorption line shape matched an observed HIPWAC absorption feature at the same areographic position, local time, and season. The RMS deviation of the model from the data was slightly smaller for the GCM-generated profile than for a line shape produced by a constant-with-height profile, even though the total column abundances were the same, showing potential for testing and constraining GCM ozone-profiles. The resulting ozone column abundance from matching the model to the HIPWAC line shape was 60% higher than that observed by SPICAM at the same areographic position one day earlier and 2.5 hours earlier in local time. This could be due to day-to-day, diurnal, or north polar region variability, or to measurement sensitivity to the ozone column and its distribution, and these possibilities will be explored. This work was supported by NASA's Planetary Astronomy Program.

Method for shaping sheet thermoplastic and the like

NASA Technical Reports Server (NTRS)

Akilian, Mireille K. (Inventor); Schattenburg, Mark L. (Inventor)

2011-01-01

Processes and apparati for shaping sheet glass or thermoplastic materials use force from a layer of a flowing fluid, such as air, between the sheet and a mandrel at close to the softening temperature of the thermoplastic. The shape is preserved by cooling. The shape of the air bearing mandrel and the pressure distribution of the fluid contribute to the final shape. A process can be conducted on one or two surfaces such that the force from the air layer is on one or two surfaces of the sheet. The gap size between the sheet and mandrel determines the pressure profile in the gap, which also determines the final sheet shape. In general, smaller gaps lead to larger viscous forces. The pressure profile depends on the shape of the mandrel, the size of the fluid gap and the sheet and the fluid supply pressure.

Scanning electron microscope measurement of width and shape of 10nm patterned lines using a JMONSEL-modeled library.

PubMed

Villarrubia, J S; Vladár, A E; Ming, B; Kline, R J; Sunday, D F; Chawla, J S; List, S

2015-07-01

The width and shape of 10nm to 12 nm wide lithographically patterned SiO2 lines were measured in the scanning electron microscope by fitting the measured intensity vs. position to a physics-based model in which the lines' widths and shapes are parameters. The approximately 32 nm pitch sample was patterned at Intel using a state-of-the-art pitch quartering process. Their narrow widths and asymmetrical shapes are representative of near-future generation transistor gates. These pose a challenge: the narrowness because electrons landing near one edge may scatter out of the other, so that the intensity profile at each edge becomes width-dependent, and the asymmetry because the shape requires more parameters to describe and measure. Modeling was performed by JMONSEL (Java Monte Carlo Simulation of Secondary Electrons), which produces a predicted yield vs. position for a given sample shape and composition. The simulator produces a library of predicted profiles for varying sample geometry. Shape parameter values are adjusted until interpolation of the library with those values best matches the measured image. Profiles thereby determined agreed with those determined by transmission electron microscopy and critical dimension small-angle x-ray scattering to better than 1 nm. Published by Elsevier B.V.

80GHz waveform generator by optical Fourier synthesis of four spectral sidebands (Conference Presentation)

NASA Astrophysics Data System (ADS)

Fatome, Julien; Hammani, Kamal; Kibler, Bertrand; Finot, Christophe

2016-04-01

Versatile and easy to implement methods to generate arbitrary optical waveforms at high repetition rates are of considerable interest with applications in optical communications, all-optical signal processing, instrumentation systems and microwave signal manipulation. While shaping sinusoidal, Gaussian or hyperbolic secant intensity profiles is commonly achieved by means of modulators or mode-locked lasers, other pulse profiles such as parabolic, triangular or flat-top shapes still remain challenging to synthesize. In this context, several strategies were already explored. First, the linear pulse shaping is a common method to carve an initial ultrashort pulse train into the desired shape. The line-by-line shaping of a coherent frequency comb made of tens of spectral components was also investigated to generate more complex structures whereas Fourier synthesis of a few discrete frequencies spectrum was exploited to efficiently generate high-fidelity ultrafast periodic intensity profiles. Besides linear shaping techniques, several nonlinear methods were implemented to benefit from the adiabatic evolution of the intensity pulse profile upon propagation in optical fibers. Other examples of efficient methods are based on the photonic generation involving specific Mach-Zehnder modulators, microwave photonic filters as well as frequency-to-time conversion. In this contribution, we theoretically and experimentally demonstrate a new approach enabling the synthesis of periodic high-repetition rate pulses with various intensity profiles ranging from parabola to triangular and flat-top pulses. More precisely by linear phase and amplitude shaping of only four spectral lines is it possible to reach the targeted temporal profile. Indeed, tailoring the input symmetric spectrum only requires the determination of two physical parameters: the phase difference between the inner and outer spectral sidebands and the ratio between the amplitude of these sidebands. Therefore, a systematic bidimensional analysis provides the optimum parameters and also highlights that switching between the different waveforms is achieved by simply changing the spectral phase between the inner and outer sidebands. We successfully validate this concept with the generation of high-fidelity ultrafast periodic waveforms at 40 GHz by shaping with a liquid cristal on insulator a four sideband comb resulting from a phase-modulated continuous wave. In order to reach higher repetition rates, we also describe a new scenario to obtain the required initial spectrum by taking advantage of the four-wave mixing process occurring in a highly nonlinear fiber. This approach is experimentally implemented at a repetition rate of 80-GHz by use of intensity and phase measurements that stress that full-duty cycle, high-quality, triangular, parabolic or flat-top profiles are obtained in full agreement with numerical simulations. The reconfigurable property of this photonic waveform generator is confirmed. Finally, the generation of bunch of shaped pulses is investigated, as well as the impact of Brillouin backscattering.

Late Quaternary history of contourite drifts and variations in Labrador Current flow, Flemish Pass, offshore eastern Canada

NASA Astrophysics Data System (ADS)

Marshall, Nicole R.; Piper, David J. W.; Saint-Ange, Francky; Campbell, D. Calvin

2014-10-01

Contourite drifts of alternating sand and mud, shaped by the Labrador Current, formed during the late Quaternary in Flemish Pass seaward of the Grand Banks of Newfoundland, Canada. The drifts preserve a record of Labrador Current flow variations through the last glacial maximum. A high-resolution seismic profile and a transect of four cores were collected across Beothuk drift on the southeast side of Flemish Pass. Downcore and lateral trends in grain size and sedimentation rate provide evidence that, between 16 and 13 ka, sediment was partitioned across Beothuk drift and the adjacent Flemish Pass floor by a strong current flow but, from 29 to 16 ka, sedimentation was more of a blanketing style, represented by draped reflections interpreted as being due to a weaker current. The data poorly resolve the low sedimentation rates since 13 ka, but the modern Labrador Current in Flemish Pass is the strongest it has been in at least the past 29 ka. Pre-29 ka current flow is interpreted based on reflection architecture in seismic profiles. A prominent drift on the southwestern side of Flemish Pass formed above a mid-Miocene erosion surface, but was buried by a mass-transport deposit after the penultimate glacial maximum and after drift deposition switched to eastern Flemish Pass. These findings illustrate the temporal complexity of drift sedimentation and provide the first detailed proxy for Labrador Current flow since the last glacial maximum.

Poster — Thur Eve — 02: Measurement of CT radiation profile width using Fuji CR imaging plate raw data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bjarnason, T A; Department of Radiology, University of British Columbia, Vancouver; Yang, C J

2014-08-15

Measuring the CT collimation width and assessing the shape of the overall profile is a relatively straightforward quality control (QC) measure that impacts both image quality and patient dose, and is often required at acceptance and routine testing. Most CT facilities have access to computed radiography (CR) systems, so performing CT collimation profile assessments using CR plates requires no additional equipment. Previous studies have shown how to effectively use CR plates to measure the radiation profile width. However, a major limitation of the previous work is that the full dynamic range of CR detector plates are not used, since themore » CR processing technology reduces the dynamic range of the DICOM output to 2{sup 10}, requiring the sensitivity and latitude settings of CR reader to be adjusted to prevent clipping of the CT profile data. Such adjustments to CR readers unnecessarily complicate the QC procedure. These clipping artefacts hinder the ability to accurately assess CT collimation width because the full-width at half maximum value of the penumbras are not properly determined if the maximum dose of the profile is not available. Furthermore, any inconsistencies in the radiation profile shape are lost if the profile plateau is clipped off. In this work we developed an opensource Matlab script for straightforward CT profile width measurements using raw CR data that also allows assessment of the profile shape without clipping, and applied this approach during CT QC.« less

Evaluation of fruit quality, bioactive compounds and total antioxidant activity of flat peach cultivars.

PubMed

Di Vaio, Claudio; Marallo, Nadia; Graziani, Giulia; Ritieni, Alberto; Di Matteo, Antonio

2015-08-15

Fruit quality traits (fresh weight, dry weight, soluble solids content, titratable acidity and firmness) as well as the content of bioactive compounds (phenolic compounds) and total antioxidant activity were evaluated in four commercial cultivars of peach (Greta, Ufo 4, Rome Star and Ufo 6) and four of nectarine (Neve, Planet 1, Maria Carla and Mesembrina) differing in fruit shape (standard or flat) and flesh colour (white or yellow), important cultivars of the Italian and foreign market. The higher fruit organoleptic quality and nutritional profile of flat peach and nectarine cultivars make them candidates for exploiting new market opportunities and the chance to improve profits of farmers. The results showed that assayed quality parameters differed greatly among cultivars. In particular, flesh color and fruit shape accounted for most of the variation in traits underlying organoleptic and nutritional quality. Overall data suggested that the flat white-fleshed nectarine Planet 1, the yellow-fleshed nectarine Mesembrina and the yellow-fleshed peach Ufo 6, because of their profiles in terms of soluble solids content, titratable acidity and bioactive compounds, have the greatest potential to meet current consumer requirements. © 2014 Society of Chemical Industry.

High Resolution Asteroid Profile by Multi Chord Occultation Observations

NASA Astrophysics Data System (ADS)

Degenhardt, Scott

2009-05-01

For millennia man has observed celestial objects occulting other bodies and distant stars. We have used these celestial synchronicities to measure the properties of objects. On January 1, 1801 Italian astronomer Giusappe Piazzi discovered the first asteroid that would soon be named Ceres. To date 190,000 of these objects have been catalogued, but only a fraction of these have accurate measurements of their true size and shape. The International Occultation Timing Association (IOTA) currently facilitates the prediction and reduction of asteroidal occultations. By measuring the shadow cast on the earth by an asteroid during a stellar occultation one can directly measure the physical size, shape, and position in space of this body to accuracies orders of magnitudes better than the best ground based adaptive optics telescope and can provide verification to 3D inverted reflective lightcurve prediction models. Recent novel methods developed by IOTA involving an individual making multiple observations through unattended remote observing stations have made way for numerous chords of occultation measurement through a single body yielding high resolution profiles of asteroid bodies. Methodology of how observing stations are deployed will be demonstrated, results of some of these observations are presented as comparisons to their inverted lightcurve are shown.

Anatomy of the nasal profile

PubMed Central

Anderson, K J; Henneberg, M; Norris, R M

2008-01-01

There is a lack in the understanding of the variation within the thickness of the soft tissue structures (muscle, skin and fat) overlying the cartilaginous skeleton of the nose and their relationship to the dorsum shape. We examined such relationships by dissecting noses of six adult female and six adult male cadavers, comparing the internal anatomical structures to the external nasal profile. We found that the soft tissue structures differ in thickness along the dorsum and that these differences are individualized. Specifically, continuous presence of subcutaneous fat from root to tip was found in half the sample, one nose had fat only on the tip, another one only on the root, the four others at both positions. The nasalis muscle was identifiable in nine of the 12 noses, transversing the nose in half the sample, and in the remaining three, only the lateral section of the muscle was identified. The superior border of the septal cartilage does not form a linear extension of the profile contour of the nasal bones but angles downwards. The actual profile contour of the dorsum does not follow the profile of the nasal bones or the septal cartilage. These results may influence the current use of nasal guidelines in forensic facial approximation. PMID:19172735

Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe

NASA Astrophysics Data System (ADS)

Walkden, N. R.; Adamek, J.; Allan, S.; Dudson, B. D.; Elmore, S.; Fishpool, G.; Harrison, J.; Kirk, A.; Komm, M.

2015-02-01

The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential, the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile, an estimate of the radial electric field is extracted which is shown to be of the order ˜1 kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the ER measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from E × B motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak.

The mathematical and computer modeling of the worm tool shaping

NASA Astrophysics Data System (ADS)

Panchuk, K. L.; Lyashkov, A. A.; Ayusheev, T. V.

2017-06-01

Traditionally mathematical profiling of the worm tool is carried out on the first T. Olivier method, known in the theory of gear gearings, with receiving an intermediate surface of the making lath. It complicates process of profiling and its realization by means of computer 3D-modeling. The purpose of the work is the improvement of mathematical model of profiling and its realization based on the methods of 3D-modeling. Research problems are: receiving of the mathematical model of profiling which excludes the presence of the making lath in it; realization of the received model by means of frame and superficial modeling; development and approbation of technology of solid-state modeling for the solution of the problem of profiling. As the basic, the kinematic method of research of the mutually envelope surfaces is accepted. Computer research is executed by means of CAD based on the methods of 3D-modeling. We have developed mathematical model of profiling of the worm tool; frame, superficial and solid-state models of shaping of the mutually enveloping surfaces of the detail and the tool are received. The offered mathematical models and the technologies of 3D-modeling of shaping represent tools for theoretical and experimental profiling of the worm tool. The results of researches can be used at design of metal-cutting tools.

THE MASS PROFILE AND SHAPE OF BARS IN THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G): SEARCH FOR AN AGE INDICATOR FOR BARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Taehyun; Lee, Myung Gyoon; Sheth, Kartik

2015-01-20

We have measured the radial light profiles and global shapes of bars using two-dimensional 3.6 μm image decompositions for 144 face-on barred galaxies from the Spitzer Survey of Stellar Structure in Galaxies. The bar surface brightness profile is correlated with the stellar mass and bulge-to-total (B/T) ratio of their host galaxies. Bars in massive and bulge-dominated galaxies (B/T > 0.2) show a flat profile, while bars in less massive, disk-dominated galaxies (B/T ∼ 0) show an exponential, disk-like profile with a wider spread in the radial profile than in the bulge-dominated galaxies. The global two-dimensional shapes of bars, however, are rectangular/boxy, independentmore » of the bulge or disk properties. We speculate that because bars are formed out of disks, bars initially have an exponential (disk-like) profile that evolves over time, trapping more disk stars to boxy bar orbits. This leads bars to become stronger and have flatter profiles. The narrow spread of bar radial profiles in more massive disks suggests that these bars formed earlier (z > 1), while the disk-like profiles and a larger spread in the radial profile in less massive systems imply a later and more gradual evolution, consistent with the cosmological evolution of bars inferred from observational studies. Therefore, we expect that the flatness of the bar profile can be used as a dynamical age indicator of the bar to measure the time elapsed since the bar formation. We argue that cosmic gas accretion is required to explain our results on bar profile and the presence of gas within the bar region.« less

Adaptive temperature profile control of a multizone crystal growth furnace

NASA Technical Reports Server (NTRS)

Batur, C.; Sharpless, R. B.; Duval, W. M. B.; Rosenthal, B. N.

1991-01-01

An intelligent measurement system is described which is used to assess the shape of a crystal while it is growing inside a multizone transparent furnace. A color video imaging system observes the crystal in real time, and determines the position and the shape of the interface. This information is used to evaluate the crystal growth rate, and to analyze the effects of translational velocity and temperature profiles on the shape of the interface. Creation of this knowledge base is the first step to incorporate image processing into furnace control.

Swiftly moving focus points and forming shapes through the scattering media

NASA Astrophysics Data System (ADS)

Tran, Vinh; Sahoo, Sujit Kumar; Tang, Dongliang; Dang, Cuong

2018-02-01

Propagation of light through scattering media such as ground glass or biological tissue limits the quality and intensity of focusing point. Wave front shaping technique which uses spatial light modulator (SLM) devices to reshape the field profile of incoming light, is considered as one of the most effective and convenient methods. Advanced biomedical or manufacturing applications require drawing various contours or shapes quickly and precisely. However, creating each shape behind the scattering medium needs different phase profiles, which are time consuming to optimize or measure. Here, we demonstrate a technique to draw various shapes or contours behind the scattering medium by swiftly moving the focus point without any mechanical movements. Our technique relies on the existence of speckle correlation property in scattering media, also known as optical memory effect. In our procedure, we first modulate the phase-only SLM to create the focus point on the other side of scattering medium. Then, we digitally shift the preoptimized phase profile on the SLM and ramp it to tilt the beam accordingly. Now, the incoming beam with identical phase profile shines on the same scattering region at a tilted angle to regenerate the focus point at the desired position due to memory effect. Moreover, with linear combination of different field patterns, we can generate a single phase profile on SLM to produce two, three or more focus points simultaneously on the other side of a turbid medium. Our method could provide a useful tool for prominent applications such as opto-genetic excitation, minimally invasive laser surgery and other related fields.

Reconstructing surface wave profiles from reflected acoustic pulses using multiple receivers.

PubMed

Walstead, Sean P; Deane, Grant B

2014-08-01

Surface wave shapes are determined by analyzing underwater reflected acoustic signals collected at multiple receivers. The transmitted signals are of nominal frequency 300 kHz and are reflected off surface gravity waves that are paddle-generated in a wave tank. An inverse processing algorithm reconstructs 50 surface wave shapes over a length span of 2.10 m. The inverse scheme uses a broadband forward scattering model based on Kirchhoff's diffraction formula to determine wave shapes. The surface reconstruction algorithm is self-starting in that source and receiver geometry and initial estimates of wave shape are determined from the same acoustic signals used in the inverse processing. A high speed camera provides ground-truth measurements of the surface wave field for comparison with the acoustically derived surface waves. Within Fresnel zone regions the statistical confidence of the inversely optimized surface profile exceeds that of the camera profile. Reconstructed surfaces are accurate to a resolution of about a quarter-wavelength of the acoustic pulse only within Fresnel zones associated with each source and receiver pair. Multiple isolated Fresnel zones from multiple receivers extend the spatial extent of accurate surface reconstruction while overlapping Fresnel zones increase confidence in the optimized profiles there.

Distributed Sensing and Shape Control of Piezoelectric Bimorph Mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Redmond, James M.; Barney, Patrick S.; Henson, Tammy D.

1999-07-28

As part of a collaborative effort between Sandia National Laboratories and the University of Kentucky to develop a deployable mirror for remote sensing applications, research in shape sensing and control algorithms that leverage the distributed nature of electron gun excitation for piezoelectric bimorph mirrors is summarized. A coarse shape sensing technique is developed that uses reflected light rays from the sample surface to provide discrete slope measurements. Estimates of surface profiles are obtained with a cubic spline curve fitting algorithm. Experiments on a PZT bimorph illustrate appropriate deformation trends as a function of excitation voltage. A parallel effort to effectmore » desired shape changes through electron gun excitation is also summarized. A one dimensional model-based algorithm is developed to correct profile errors in bimorph beams. A more useful two dimensional algorithm is also developed that relies on measured voltage-curvature sensitivities to provide corrective excitation profiles for the top and bottom surfaces of bimorph plates. The two algorithms are illustrated using finite element models of PZT bimorph structures subjected to arbitrary disturbances. Corrective excitation profiles that yield desired parabolic forms are computed, and are shown to provide the necessary corrective action.« less

The effect of learning on bursting.

PubMed

Stegenga, Jan; Le Feber, Joost; Marani, Enrico; Rutten, Wim L C

2009-04-01

We have studied the effect that learning a new stimulus-response (SR) relationship had within a neuronal network cultured on a multielectrode array. For training, we applied repetitive focal electrical stimulation delivered at a low rate (<1/s). Stimulation was withdrawn when a desired SR success ratio was achieved. It has been shown elsewhere, and we verified that this training algorithm, named conditional repetitive stimulation (CRS), can be used to strengthen an initially weak SR. So far, it remained unclear what the role of the rest of the network during learning was. We therefore studied the effect of CRS on spontaneously occurring network bursts. To this end, we made profiles of the firing rates within network bursts. We have earlier shown that these profiles change shape on a time base of several hours during spontaneous development. We show here that profiles of summed activity, called burst profiles, changed shape at an increased rate during CRS. This suggests that the whole network was involved in making the changes necessary to incorporate the desired SR relationship. However, a local (path-specific) component to learning was also found by analyzing profiles of single-electrode-activity phase profiles. Phase profiles that were not part of the SR relationship changed far less during CRS than the phase profiles of the electrodes that were part of the SR relationship. Finally, the manner in which phase profiles changed shape varied and could not be linked to the SR relationship.

A dimensional comparison between embedded 3D-printed and silicon microchannels

NASA Astrophysics Data System (ADS)

O'Connor, J.; Punch, J.; Jeffers, N.; Stafford, J.

2014-07-01

The subject of this paper is the dimensional characterization of embedded microchannel arrays created using contemporary 3D-printing fabrication techniques. Conventional microchannel arrays, fabricated using deep reactive ion etching techniques (DRIE) and wet-etching (KOH), are used as a benchmark for comparison. Rectangular and trapezoidal cross-sectional shapes were investigated. The channel arrays were 3D-printed in vertical and horizontal directions, to examine the influence of print orientation on channel characteristics. The 3D-printed channels were benchmarked against Silicon channels in terms of the following dimensional characteristics: cross-sectional area (CSA), perimeter, and surface profiles. The 3D-printed microchannel arrays demonstrated variances in CSA of 6.6-20% with the vertical printing approach yielding greater dimensional conformity than the horizontal approach. The measured CSA and perimeter of the vertical channels were smaller than the nominal dimensions, while the horizontal channels were larger in both CSA and perimeter due to additional side-wall roughness present throughout the channel length. This side-wall roughness caused significant shape distortion. Surface profile measurements revealed that the base wall roughness was approximately the resolution of current 3D-printers. A spatial periodicity was found along the channel length which appeared at different frequencies for each channel array. This paper concludes that vertical 3D-printing is superior to the horizontal printing approach, in terms of both dimensional fidelity and shape conformity and can be applied in microfluidic device applications.

Label-Free Quantitation of Ribosomal Proteins from Bacillus subtilis for Antibiotic Research.

PubMed

Schäkermann, Sina; Prochnow, Pascal; Bandow, Julia E

2017-01-01

Current research is focusing on ribosome heterogeneity as a response to changing environmental conditions and stresses, such as antibiotic stress. Altered stoichiometry and composition of ribosomal proteins as well as association of additional protein factors are mechanisms for shaping the protein expression profile or hibernating ribosomes. Here, we present a method for the isolation of ribosomes to analyze antibiotic-induced changes in the composition of ribosomes in Bacillus subtilis or other bacteria. Ribosomes and associated proteins are isolated by ultracentrifugation and proteins are identified and quantified using label-free mass spectrometry.

Degradation studies of Martian impact craters

NASA Technical Reports Server (NTRS)

Barlow, N. G.

1991-01-01

The amount of obliteration suffered by Martian impact craters is quantified by comparing measurable attributes of the current crater shape to those values expected for a fresh crater of identical size. Crater diameters are measured from profiles obtained using photoclinometry across the structure. The relationship between the diameter of a fresh crater and a crater depth, floor width, rim height, central peak height, etc. was determined by empirical studies performed on fresh Martian impact craters. We utilized the changes in crater depth and rim height to judge the degree of obliteration suffered by Martian impact craters.

Dynamics of a high-current relativistic electron beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strelkov, P. S., E-mail: strelkov@fpl.gpi.ru; Tarakanov, V. P., E-mail: karat@gmail.ru; Ivanov, I. E., E-mail: iei@fpl.gpi.ru

2015-06-15

The dynamics of a high-current relativistic electron beam is studied experimentally and by numerical simulation. The beam is formed in a magnetically insulated diode with a transverse-blade explosive-emission cathode. It is found experimentally that the radius of a 500-keV beam with a current of 2 kA and duration of 500 ns decreases with time during the beam current pulse. The same effect was observed in numerical simulations. This effect is explained by a change in the shape of the cathode plasma during the current pulse, which, according to calculations, leads to a change in the beam parameters, such as themore » electron pitch angle and the spread over the longitudinal electron momentum. These parameters are hard to measure experimentally; however, the time evolution of the radial profile of the beam current density, which can be measured reliably, coincides with the simulation results. This allows one to expect that the behavior of the other beam parameters also agrees with numerical simulations.« less

Multi-pinhole collimator design for small-object imaging with SiliSPECT: a high-resolution SPECT

NASA Astrophysics Data System (ADS)

Shokouhi, S.; Metzler, S. D.; Wilson, D. W.; Peterson, T. E.

2009-01-01

We have designed a multi-pinhole collimator for a dual-headed, stationary SPECT system that incorporates high-resolution silicon double-sided strip detectors. The compact camera design of our system enables imaging at source-collimator distances between 20 and 30 mm. Our analytical calculations show that using knife-edge pinholes with small-opening angles or cylindrically shaped pinholes in a focused, multi-pinhole configuration in combination with this camera geometry can generate narrow sensitivity profiles across the field of view that can be useful for imaging small objects at high sensitivity and resolution. The current prototype system uses two collimators each containing 127 cylindrically shaped pinholes that are focused toward a target volume. Our goal is imaging objects such as a mouse brain, which could find potential applications in molecular imaging.

Spatial structure of radio frequency ring-shaped magnetized discharge sputtering plasma using two facing ZnO/Al2O3 cylindrical targets for Al-doped ZnO thin film preparation

NASA Astrophysics Data System (ADS)

Sumiyama, Takashi; Fukumoto, Takaya; Ohtsu, Yasunori; Tabaru, Tatsuo

2017-05-01

Spatial structure of high-density radio frequency ring-shaped magnetized discharge plasma sputtering with two facing ZnO/Al2O3 cylindrical targets mounted in ring-shaped hollow cathode has been measured and Al-doped ZnO (AZO) thin film is deposited without substrate heating. The plasma density has a peak at ring-shaped hollow trench near the cathode. The radial profile becomes uniform with increasing the distance from the target cathode. A low ion current flowing to the substrate of 0.19 mA/cm2 is attained. Large area AZO films with a resistivity of 4.1 - 6.7×10-4 Ω cm can be prepared at a substrate room temperature. The transmittance is 84.5 % in a visible region. The surface roughnesses of AZO films are 0.86, 0.68, 0.64, 1.7 nm at radial positions of r = 0, 15, 30, 40 mm, respectively, while diffraction peak of AZO films is 34.26°. The grains exhibit a preferential orientation along (002) axis.

Tracking and shape errors measurement of concentrating heliostats

NASA Astrophysics Data System (ADS)

Coquand, Mathieu; Caliot, Cyril; Hénault, François

2017-09-01

In solar tower power plants, factors such as tracking accuracy, facets misalignment and surface shape errors of concentrating heliostats are of prime importance on the efficiency of the system. At industrial scale, one critical issue is the time and effort required to adjust the different mirrors of the faceted heliostats, which could take several months using current techniques. Thus, methods enabling quick adjustment of a field with a huge number of heliostats are essential for the rise of solar tower technology. In this communication is described a new method for heliostat characterization that makes use of four cameras located near the solar receiver and simultaneously recording images of the sun reflected by the optical surfaces. From knowledge of a measured sun profile, data processing of the acquired images allows reconstructing the slope and shape errors of the heliostats, including tracking and canting errors. The mathematical basis of this shape reconstruction process is explained comprehensively. Numerical simulations demonstrate that the measurement accuracy of this "backward-gazing method" is compliant with the requirements of solar concentrating optics. Finally, we present our first experimental results obtained at the THEMIS experimental solar tower plant in Targasonne, France.

Profiles of Adolescents' Perceptions of Democratic Classroom Climate and Students' Influence: The Effect of School and Community Contexts.

PubMed

Reichert, Frank; Chen, Jiaxin; Torney-Purta, Judith

2018-06-01

Students' learning experiences and outcomes are shaped by school and classroom contexts. Many studies have shown how an open, democratic classroom climate relates to learning in the citizenship domain and helps nurture active and engaged citizens. However, little research has been undertaken to look at how such a favorable classroom climate may work together with broader school factors. The current study examines data from 14,292 Nordic eighth graders (51% female) who had participated in the International Civic and Citizenship Education Study in 2009, as well as contextual data from 5,657 teachers and 618 principals. Latent class analysis identifies profiles of students' perceptions of school context, which are further examined with respect to the contextual correlates at the school level using two-level fixed effects multinomial regression analyses. Five distinct student profiles are identified and labeled "alienated", "indifferent", "activist", "debater", and "communitarian". Compared to indifferent students, debaters and activists appear more frequently at schools with relatively few social problems; being in the communitarian group is associated with aspects of the wider community. Furthermore, being in one of these three groups (and not in the indifferent group) is more likely when teachers act as role models by engaging in school governance. The results are discussed within the framework of ecological assets and developmental niches for emergent participatory citizenship. The implications are that adults at school could enhance multiple contexts that shape adolescents' developmental niches to nurture active and informed citizens for democracies.

Profile of Secondary School Students with High Mathematics Ability in Solving Shape and Space Problem

ERIC Educational Resources Information Center

Putra, Mulia; Novita, Rita

2015-01-01

This study aimed to describe the profile of secondary school students with high mathematics ability in solving shape and space problem in PISA (Program for International Student Assessment). It is a descriptive research with a qualitative approach, in which the subjects in this study were students of class VIII SMP N 1 Banda Aceh. The results show…

Effects of current on droplet generation and arc plasma in gas metal arc welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, J.; Tsai, H. L.

2006-09-01

In gas metal arc welding (GMAW), a technology using pulsed currents has been employed to achieve the one-droplet-per-pulse (ODPP) metal transfer mode with the advantages of low average currents, a stable and controllable droplet generation, and reduced spatter. In this paper, a comprehensive model was developed to study the effects of different current profiles on the droplet formation, plasma generation, metal transfer, and weld pool dynamics in GMAW. Five types of welding currents were studied, including two constant currents and three wave form currents. In each type, the transient temperature and velocity distributions of the arc plasma and the moltenmore » metal, and the shapes of the droplet and the weld pool were calculated. The results showed that a higher current generates smaller droplets, higher droplet frequency, and higher electromagnetic force that becomes the dominant factor detaching the droplet from the electrode tip. The model has demonstrated that a stable ODPP metal transfer mode can be achieved by choosing a current with proper wave form for given welding conditions.« less

X-ray beam-shaping via deformable mirrors: surface profile and point spread function computation for Gaussian beams using physical optics.

PubMed

Spiga, D

2018-01-01

X-ray mirrors with high focusing performances are commonly used in different sectors of science, such as X-ray astronomy, medical imaging and synchrotron/free-electron laser beamlines. While deformations of the mirror profile may cause degradation of the focus sharpness, a deliberate deformation of the mirror can be made to endow the focus with a desired size and distribution, via piezo actuators. The resulting profile can be characterized with suitable metrology tools and correlated with the expected optical quality via a wavefront propagation code or, sometimes, predicted using geometric optics. In the latter case and for the special class of profile deformations with monotonically increasing derivative, i.e. concave upwards, the point spread function (PSF) can even be predicted analytically. Moreover, under these assumptions, the relation can also be reversed: from the desired PSF the required profile deformation can be computed analytically, avoiding the use of trial-and-error search codes. However, the computation has been so far limited to geometric optics, which entailed some limitations: for example, mirror diffraction effects and the size of the coherent X-ray source were not considered. In this paper, the beam-shaping formalism in the framework of physical optics is reviewed, in the limit of small light wavelengths and in the case of Gaussian intensity wavefronts. Some examples of shaped profiles are also shown, aiming at turning a Gaussian intensity distribution into a top-hat one, and checks of the shaping performances computing the at-wavelength PSF by means of the WISE code are made.

Analysis of Vibration and Acoustic Noise in Permanent Magnet Motors.

NASA Astrophysics Data System (ADS)

Hwang, Sangmoon

The drive motor is a frequent source of vibration and acoustic noise in many precision spindle motors. One of the electromagnetic sources of vibration in permanent magnet motors is the torque ripple, consisting of the reluctance torque and electromagnetic torque fluctuation. This type of vibration is becoming more serious with the advent of new high-grade magnets with increased flux density. Acoustic noise of electromagnetic origin is difficult to predict and its exact mechanism is unclear. The mechanism of noise generation should be revealed to design a quieter motor which is the modern customer's demand. For motor operation at low speeds and loads, torque ripple due to the reluctance torque is often a source of vibration and control difficulty. The reluctance torque in a motor was calculated from the flux density by a finite element method and the Maxwell stress method. Effects of design parameters, such as stator slot width, permanent slot width, airgap length and magnetization direction, were investigated. Magnet pole shaping, by gradually decreasing the magnet thickness toward edges, yields a sinusoidal shape of the reluctance torque with reduced harmonics, thus reducing the vibration. This dissertation also presents two motor design techniques: stator tooth notching and rotor pole skewing with magnet pole shaping, and the effect of each method on the output torque. The analysis shows that the reluctance torque can be nearly eliminated by the suggested designs, with minimal sacrifice of the output torque. In permanent magnet DC motors, the most popular design type is the trapezoidal back electro-motive force (BEMF), for switched DC controllers. It is demonstrated that the output torque profile of one phase energized is qualitatively equivalent to the BEMF profile for motors with reduced reluctance torque. It implies that design of BEMF profile is possible by magnetic modeling of a motor, without expensive and time-consuming experiments for different designs. The effect of various design parameters on the output torque and torque ripple are discussed. Design parameters include winding patterns, magnetization direction, magnet arc length, number of segments in poles and magnet pole shaping. New designs of trapezoidal BEMF motors are proposed to reduce the electromagnetic torque ripple. Magnet stepping and magnet edge shaping with reduced arc length, significantly reduce torque ripple, with minimal sacrifice of the maximum output torque. Acoustic noise of electromagnetic origin is investigated using a magnetic frame which emulates a DC motor. The driving electromagnetic force is calculated using finite element analysis and the resulting vibration and acoustic noise is measured. Acoustic noise of purely electromagnetic origin was also tested with a DC brushless motor to confirm the results of the magnetic frame. The mechanism of noise generation in a DC motor is a quasi-static response of a stator not only at the fundamental frequency but also at higher harmonic frequencies of alternating switched DC, which is a current characteristic of a DC motor. Noise generation is significantly aggravated when some of those harmonics are close to the resonant frequencies of the stator. Therefore, acoustic noise is highly dependent upon the excitation current shape, as higher harmonics may match with resonant frequencies of the stator.

Plasma shape control by pulsed solenoid on laser ion source

NASA Astrophysics Data System (ADS)

Sekine, M.; Ikeda, S.; Romanelli, M.; Kumaki, M.; Fuwa, Y.; Kanesue, T.; Hayashizaki, N.; Lambiase, R.; Okamura, M.

2015-09-01

A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. However, it was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled by the pulsed magnetic field. This approach may also be useful to reduce beam emittance of a LIS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spong, D.A.; Hirshman, S.P.; Whitson, J.C.

A new class of low aspect ratio toroidal hybrid stellarators is found using more general plasma confinement optimization criterion than quasi-symmetrization. The plasma current profile and shape of the outer magnetic flux surface are used as control variables to achieve near constancy of the longitudinal invariant J* on internal flux surfaces (quasi-omnigeneity), in addition to a number of other desirable physics target properties. We find that a range of compact (small aspect ratio A), high {beta} (ratio of thermal energy to magnetic field energy), low plasma current devices exist which have significantly improved confinement both for thermal as well asmore » energetic (collisionless) particle components. With reasonable increases in magnetic field and geometric size, such devices can also be scaled to confine 3.5 MeV alpha particle orbits.« less

Plasma shape control by pulsed solenoid on laser ion source

DOE PAGES

Sekine, M.; Ikeda, S.; Romanelli, M.; ...

2015-05-28

A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. It was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled bymore » the pulsed magnetic field. Thus, this approach may also be useful to reduce beam emittance of a LIS.« less

Investigation of the geometrical barrier in Bi-2212 using the magneto-optical technique

NASA Astrophysics Data System (ADS)

Lin, Z. W.; Gu, G. D.; Russell, G. J.

2000-08-01

It has been found that the penetration of vortices into a weak pinning crystal is governed by a geometrical barrier and they form a dome-shaped flux profile across the crystal. Using the powerful magneto-optical technique, we investigated this geometrical barrier in a high-purity Bi2Sr2CaCu2O8+x single-crystal platelet. Our results show that over the temperature range 20-70 K the dome-shaped profile is observed. Also, the influences of the edge shape and the roughness on the geometrical barrier are discussed.

Analyzing gene expression time-courses based on multi-resolution shape mixture model.

PubMed

Li, Ying; He, Ye; Zhang, Yu

2016-11-01

Biological processes actually are a dynamic molecular process over time. Time course gene expression experiments provide opportunities to explore patterns of gene expression change over a time and understand the dynamic behavior of gene expression, which is crucial for study on development and progression of biology and disease. Analysis of the gene expression time-course profiles has not been fully exploited so far. It is still a challenge problem. We propose a novel shape-based mixture model clustering method for gene expression time-course profiles to explore the significant gene groups. Based on multi-resolution fractal features and mixture clustering model, we proposed a multi-resolution shape mixture model algorithm. Multi-resolution fractal features is computed by wavelet decomposition, which explore patterns of change over time of gene expression at different resolution. Our proposed multi-resolution shape mixture model algorithm is a probabilistic framework which offers a more natural and robust way of clustering time-course gene expression. We assessed the performance of our proposed algorithm using yeast time-course gene expression profiles compared with several popular clustering methods for gene expression profiles. The grouped genes identified by different methods are evaluated by enrichment analysis of biological pathways and known protein-protein interactions from experiment evidence. The grouped genes identified by our proposed algorithm have more strong biological significance. A novel multi-resolution shape mixture model algorithm based on multi-resolution fractal features is proposed. Our proposed model provides a novel horizons and an alternative tool for visualization and analysis of time-course gene expression profiles. The R and Matlab program is available upon the request. Copyright © 2016 Elsevier Inc. All rights reserved.

Beam shaping in high-power laser systems with using refractive beam shapers

NASA Astrophysics Data System (ADS)

Laskin, Alexander; Laskin, Vadim

2012-06-01

Beam Shaping of the spatial (transverse) profile of laser beams is highly desirable by building optical systems of high-power lasers as well in various applications with these lasers. Pumping of the crystals of Ti:Sapphire lasers by the laser radiation with uniform (flattop) intensity profile improves performance of these ultrashort pulse high-power lasers in terms of achievable efficiency, peak-power and stability, output beam profile. Specifications of the solid-state lasers built according to MOPA configuration can be also improved when radiation of the master oscillator is homogenized and then is amplified by the power amplifier. Features of building these high power lasers require that a beam shaping solution should be capable to work with single mode and multimode beams, provide flattop and super-Gauss intensity distributions, the consistency and divergence of a beam after the intensity re-distribution should be conserved and low absorption provided. These specific conditions are perfectly fulfilled by the refractive field mapping beam shapers due to their unique features: almost lossless intensity profile transformation, low output divergence, high transmittance and flatness of output beam profile, extended depth of field, adaptability to real intensity profiles of TEM00 and multimode laser sources. Combining of the refractive field mapping beam shapers with other optical components, like beam-expanders, relay imaging lenses, anamorphic optics makes it possible to generate the laser spots of necessary shape, size and intensity distribution. There are plenty of applications of high-power lasers where beam shaping bring benefits: irradiating photocathode of Free Electron Lasers (FEL), material ablation, micromachining, annealing in display making techniques, cladding, heat treating and others. This paper will describe some design basics of refractive beam shapers of the field mapping type, with emphasis on the features important for building and applications of high-power laser sources. There will be presented results of applying the refractive beam shapers in real installations.

Current Research in Lidar Technology Used for the Remote Sensing of Atmospheric Aerosols

PubMed Central

Comerón, Adolfo; Muñoz-Porcar, Constantino; Rocadenbosch, Francesc; Rodríguez-Gómez, Alejandro; Sicard, Michaël

2017-01-01

Lidars are active optical remote sensing instruments with unique capabilities for atmospheric sounding. A manifold of atmospheric variables can be profiled using different types of lidar: concentration of species, wind speed, temperature, etc. Among them, measurement of the properties of aerosol particles, whose influence in many atmospheric processes is important but is still poorly stated, stands as one of the main fields of application of current lidar systems. This paper presents a review on fundamentals, technology, methodologies and state-of-the art of the lidar systems used to obtain aerosol information. Retrieval of structural (aerosol layers profiling), optical (backscatter and extinction coefficients) and microphysical (size, shape and type) properties requires however different levels of instrumental complexity; this general outlook is structured following a classification that attends these criteria. Thus, elastic systems (detection only of emitted frequencies), Raman systems (detection also of Raman frequency-shifted spectral lines), high spectral resolution lidars, systems with depolarization measurement capabilities and multi-wavelength instruments are described, and the fundamentals in which the retrieval of aerosol parameters is based is in each case detailed. PMID:28632170

The confining baryonic Y-strings on the lattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakry, Ahmed S.; Chen, Xurong; Zhang, Peng-Ming

2016-01-22

In a string picture, the nucleon is conjectured as consisting of a Y-shaped gluonic string ended by constituent quarks. In this proceeding, we summarize our results on revealing the signature of the confining Y-bosonic string in the gluonic profile due to a system of three static quarks on the lattice at finite temperature. The analysis of the action density unveils a background of a filled-Δ distribution. However, we found that these Δ-shaped profiles are comprised of three Y-shaped Gaussian-like flux tubes. The length of the revealed Y-string-like distribution is maximum near the deconfinement point and approaches the geometrical minimal nearmore » the end of the QCD plateau. The action density width profile returns good fits to a baryonic string model for the junction fluctuations at large quark source separation.« less

Development of ITER non-activation phase operation scenarios

DOE PAGES

Kim, S. H.; Poli, F. M.; Koechl, F.; ...

2017-06-29

Non-activation phase operations in ITER in hydrogen (H) and helium (He) will be important for commissioning of tokamak systems, such as diagnostics, heating and current drive (HCD) systems, coils and plasma control systems, and for validation of techniques necessary for establishing operations in DT. The assessment of feasible HCD schemes at various toroidal fields (2.65–5.3 T) has revealed that the previously applied assumptions need to be refined for the ITER non-activation phase H/He operations. A study of the ranges of plasma density and profile shape using the JINTRAC suite of codes has indicated that the hydrogen pellet fuelling into Hemore » plasmas should be utilized taking the optimization of IC power absorption, neutral beam shine-through density limit and H-mode access into account. The EPED1 estimation of the edge pedestal parameters has been extended to various H operation conditions, and the combined EPED1 and SOLPS estimation has provided guidance for modelling the edge pedestal in H/He operations. The availability of ITER HCD schemes, ranges of achievable plasma density and profile shape, and estimation of the edge pedestal parameters for H/He plasmas have been integrated into various time-dependent tokamak discharge simulations. In this paper, various H/He scenarios at a wide range of plasma current (7.5–15 MA) and field (2.65–5.3 T) have been developed for the ITER non-activation phase operation, and the sensitivity of the developed scenarios to the used assumptions has been investigated to provide guidance for further development.« less

Arcjet Flow Properties Determined from Laser-Induced Fluorescence of Atomic Species

NASA Technical Reports Server (NTRS)

Fletcher, Douglas G.

1997-01-01

Flow property measurements that were recently acquired in the Ames Research Center Aerodynamic Heating Facility (AHF) arc jet using two-photon Laser-Induced Fluorescence (LIF) of atomic nitrogen and oxygen are reported. The measured properties, which include velocity, translational temperature, and species concentration, cover a wide range of facility operation for the 30 cm nozzle. During the tests, the arc jet pressure and input stream composition were maintained at fixed values and the arc current was varied to vary the flow enthalpy. As part of this ongoing effort, a measurement of the two-photon absorption coefficient for the 3p4D<-2p4S transition of atomic nitrogen was performed, and the measured value is used to convert the relative concentration measurements to absolute values. A flow reactor is used to provide a known temperature line shape profile to deconvolve the laser line width contribution to the translational temperature measurements. Results from the current experiments are compared with previous results obtained using NO-Beta line profiles at room temperature and the problem of multimode laser oscillation and its impact on the two-photon excitation line shape are discussed. One figure is attached, and this figure shows relative N atom concentration measurements as a function of the arc power. Other measurements have already been acquired and analyzed. This poster represents an application of laser-spectroscopic measurements in an important test facility. The arc jet flow facilities are heavily used in thermal protection material development and evaluation. All hypersonic flight and planetary atmospheric entry vehicles will use materials tested in these arc jet facilities.

Development of ITER non-activation phase operation scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, S. H.; Poli, F. M.; Koechl, F.

Non-activation phase operations in ITER in hydrogen (H) and helium (He) will be important for commissioning of tokamak systems, such as diagnostics, heating and current drive (HCD) systems, coils and plasma control systems, and for validation of techniques necessary for establishing operations in DT. The assessment of feasible HCD schemes at various toroidal fields (2.65–5.3 T) has revealed that the previously applied assumptions need to be refined for the ITER non-activation phase H/He operations. A study of the ranges of plasma density and profile shape using the JINTRAC suite of codes has indicated that the hydrogen pellet fuelling into Hemore » plasmas should be utilized taking the optimization of IC power absorption, neutral beam shine-through density limit and H-mode access into account. The EPED1 estimation of the edge pedestal parameters has been extended to various H operation conditions, and the combined EPED1 and SOLPS estimation has provided guidance for modelling the edge pedestal in H/He operations. The availability of ITER HCD schemes, ranges of achievable plasma density and profile shape, and estimation of the edge pedestal parameters for H/He plasmas have been integrated into various time-dependent tokamak discharge simulations. In this paper, various H/He scenarios at a wide range of plasma current (7.5–15 MA) and field (2.65–5.3 T) have been developed for the ITER non-activation phase operation, and the sensitivity of the developed scenarios to the used assumptions has been investigated to provide guidance for further development.« less

Shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals. Part 1.

PubMed

Thompson, S A; Dummer, P M

1997-01-01

The aim of this study was to determine the shaping ability of ProFile.04 Taper Series 29 nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using a step-down approach. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. The time necessary for canal preparation was not influenced significantly by canal shape. No instrument fractures occurred but a total of 52 instruments deformed. Size 6 instruments deformed the most followed by sizes 5, 3 and 4. Canal shape did not influence significantly instrument deformation. None of the canals became blocked with debris and loss of working distance was on average 0.5 mm or less. Intracanal impressions of canal form demonstrated that most canals had definite apical stops, smooth canal walls and good flow and taper. Under the conditions of this study, ProFile.04 Taper Series 29 rotary nickel-titanium instruments prepared simulated canals rapidly and created good three-dimensional form. A substantial number of instruments deformed but it was not possible to determine whether this phenomenon occurred because of the nature of the experimental model or through an inherent design weakness in the instruments.

Computation of stress on the surface of a soft homogeneous arbitrarily shaped particle.

PubMed

Yang, Minglin; Ren, Kuan Fang; Wu, Yueqian; Sheng, Xinqing

2014-04-01

Prediction of the stress on the surface of an arbitrarily shaped particle of soft material is essential in the study of elastic properties of the particles with optical force. It is also necessary in the manipulation and sorting of small particles with optical tweezers, since a regular-shaped particle, such as a sphere, may be deformed under the nonuniform optical stress on its surface. The stress profile on a spherical or small spheroidal soft particle trapped by shaped beams has been studied, however little work on computing the surface stress of an irregular-shaped particle has been reported. We apply in this paper the surface integral equation with multilevel fast multipole algorithm to compute the surface stress on soft homogeneous arbitrarily shaped particles. The comparison of the computed stress profile with that predicted by the generalized Lorenz-Mie theory for a water droplet of diameter equal to 51 wavelengths in a focused Gaussian beam show that the precision of our method is very good. Then stress profiles on spheroids with different aspect ratios are computed. The particles are illuminated by a Gaussian beam of different waist radius at different incidences. Physical analysis on the mechanism of optical stress is given with help of our recently developed vectorial complex ray model. It is found that the maximum of the stress profile on the surface of prolate spheroids is not only determined by the reflected and refracted rays (orders p=0,1) but also the rays undergoing one or two internal reflections where they focus. Computational study of stress on surface of a biconcave cell-like particle, which is a typical application in life science, is also undertaken.

Logic gate scanner focus control in high-volume manufacturing using scatterometry

NASA Astrophysics Data System (ADS)

Dare, Richard J.; Swain, Bryan; Laughery, Michael

2004-05-01

Tool matching and optimal process control are critical requirements for success in semiconductor manufacturing. It is imperative that a tool"s operating conditions are understood and controlled in order to create a process that is repeatable and produces devices within specifications. Likewise, it is important where possible to match multiple systems using some methodology, so that regardless of which tool is used the process remains in control. Agere Systems is currently using Timbre Technologies" Optical Digital Profilometry (ODP) scatterometry for controlling Nikon scanner focus at the most critical lithography layer; logic gate. By adjusting focus settings and verifying the resultant changes in resist profile shape using ODP, it becomes possible to actively control scanner focus to achieve a desired resist profile. Since many critical lithography processes are designed to produce slightly re-entrant resist profiles, this type of focus control is not possible via Critical Dimension Scanning Electron Microscopy (CDSEM) where reentrant profiles cannot be accurately determined. Additionally, the high throughput and non-destructive nature of this measurement technique saves both cycle time and wafer costs compared to cross-section SEM. By implementing an ODP daily process check and after any maintenance on a scanner, Agere successfully enabled focus drift control, i.e. making necessary focus or equipment changes in order to maintain a desired resist profile.

An in-vitro investigation of the accuracy of fit of Procera and Empress crowns.

PubMed

Fleming, Garry J R; Dobinson, Marie M; Landini, Gabriel; Harris, Jonathan J

2005-09-01

The current study aimed to investigate the accuracy of fit and the reproducibility of inner crown profile for two types of high strength ceramics, IPS Empress and Procera. Procera and Empress crowns with four different morphologies were cemented to dies using zinc phosphate dental cement. Vertical and horizontal sections were made through each of the crown/die preparations and images of the vertical sections were compared for curvature reproduction by alignment using image processing. Measurements were made on horizontal sections to determine cement layer thickness. Alignment of the crowns using image analysis identified quantifiable variations in the inner surface profile compared with the outer surface of the die. The largest differences occurred from the cusp tips to the occlusal adaptation area and differences in surface profile were less pronounced for Procera than Empress crowns. Marginal gap varied independently of ceramic or internal crown shape from 7-529 microm for Procera and 26-548 microm for Empress. IPS Empress has a superior ability to reproduce the inner surface profile of the crown morphologies investigated compared with Procera. The reduced reproduction of surface profile was associated with an increased cement thickness at the occlusal contact area that may inadvertently lead to failure of the crowns functional characteristics.

Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walkden, N. R., E-mail: nrw504@york.ac.uk; Department of Physics, York Plasma Institute, University of York, Heslington, York YO10 5DD; Adamek, J.

The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature, and radial electric field on the Mega Amp Spherical Tokamak. The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential, the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile, an estimate ofmore » the radial electric field is extracted which is shown to be of the order ∼1 kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the E{sub R} measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from E × B motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak.« less

Amplification of Dynamic Nuclear Polarization at 200 GHz by Arbitrary Pulse Shaping of the Electron Spin Saturation Profile.

PubMed

Kaminker, Ilia; Han, Songi

2018-06-07

Dynamic nuclear polarization (DNP) takes center stage in nuclear magnetic resonance (NMR) as a tool to amplify its signal by orders of magnitude through the transfer of polarization from electron to nuclear spins. In contrast to modern NMR and electron paramagnetic resonance (EPR) that extensively rely on pulses for spin manipulation in the time domain, the current mainstream DNP technology exclusively relies on monochromatic continuous wave (CW) irradiation. This study introduces arbitrary phase shaped pulses that constitute a train of coherent chirp pulses in the time domain at 200 GHz (7 T) to dramatically enhance the saturation bandwidth and DNP performance compared to CW DNP, yielding up to 500-fold in NMR signal enhancements. The observed improvement is attributed to the recruitment of additional electron spins contributing to DNP via the cross-effect mechanism, as experimentally confirmed by two-frequency pump-probe electron-electron double resonance (ELDOR).

Improved cost-effective fabrication of arbitrarily shaped μIPMC transducers

NASA Astrophysics Data System (ADS)

Feng, Guo-Hua; Chen, Ri-Hong

2008-01-01

Conventional ionic polymer-metal composite (IPMC) production cuts individual transducers from bulk IPMC sheets. This paper presents a novel photolithographic technique that grows a large array of identical devices on a thin (~µm range) parylene diaphragm supported on a perforated substrate of material that is immune to the subsequent processing liquids. In particular, the new technique relies on a unique wax fill-up and removal concept that can produce arbitrarily shaped Nafion films with micron feature size. The developed process is cheap and results in devices of high uniformity and reliability, with greater design flexibility. Microtensile testing characterizes the fracture profiles of the non-electroded Nafion film and IPMC. Young's modulus is characterized, as well as maximum displacement and current consumption under various loading, driving voltages, waveforms and frequencies. High product quality and low process costs make this process of interest for mass production of micromachined IPMC transducers.

Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance

DOE PAGES

Li, S.; Alverson, S.; Bohler, D.; ...

2017-08-17

The photocathode rf gun is one of the most critical components in x-ray free electron lasers. The drive laser strikes the photocathode surface, which emits electrons with properties that depend on the shape of the drive laser. Most free electron lasers use photocathodes with work function in the ultraviolet, a wavelength where direct laser manipulation becomes challenging. In this paper, we present a novel application of a digital micromirror device (DMD) for the 253 nm drive laser at the Linear Coherent Light Source. Laser profile shaping is accomplished through an iterative algorithm that takes into account shaping error and efficiency.more » Next, we use laser shaping to control the X-ray laser output via an online optimizer, which shows improvement in FEL pulse energy. Lastly, as a preparation for electron beam shaping, we use the DMD to measure the photocathode quantum efficiency across cathode surface with an averaged laser rms spot size of 59 μm. In conclusion, our experiments demonstrate promising outlook of using DMD to shape ultraviolet lasers for photocathode rf guns with various applications.« less

Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, S.; Alverson, S.; Bohler, D.

The photocathode rf gun is one of the most critical components in x-ray free electron lasers. The drive laser strikes the photocathode surface, which emits electrons with properties that depend on the shape of the drive laser. Most free electron lasers use photocathodes with work function in the ultraviolet, a wavelength where direct laser manipulation becomes challenging. In this paper, we present a novel application of a digital micromirror device (DMD) for the 253 nm drive laser at the Linear Coherent Light Source. Laser profile shaping is accomplished through an iterative algorithm that takes into account shaping error and efficiency.more » Next, we use laser shaping to control the X-ray laser output via an online optimizer, which shows improvement in FEL pulse energy. Lastly, as a preparation for electron beam shaping, we use the DMD to measure the photocathode quantum efficiency across cathode surface with an averaged laser rms spot size of 59 μm. In conclusion, our experiments demonstrate promising outlook of using DMD to shape ultraviolet lasers for photocathode rf guns with various applications.« less

Ultraviolet laser transverse profile shaping for improving x-ray free electron laser performance

NASA Astrophysics Data System (ADS)

Li, S.; Alverson, S.; Bohler, D.; Egger, A.; Fry, A.; Gilevich, S.; Huang, Z.; Miahnahri, A.; Ratner, D.; Robinson, J.; Zhou, F.

2017-08-01

The photocathode rf gun is one of the most critical components in x-ray free electron lasers. The drive laser strikes the photocathode surface, which emits electrons with properties that depend on the shape of the drive laser. Most free electron lasers use photocathodes with work function in the ultraviolet, a wavelength where direct laser manipulation becomes challenging. In this paper, we present a novel application of a digital micromirror device (DMD) for the 253 nm drive laser at the Linear Coherent Light Source. Laser profile shaping is accomplished through an iterative algorithm that takes into account shaping error and efficiency. Next, we use laser shaping to control the X-ray laser output via an online optimizer, which shows improvement in FEL pulse energy. Lastly, as a preparation for electron beam shaping, we use the DMD to measure the photocathode quantum efficiency across cathode surface with an averaged laser rms spot size of 59 μ m . Our experiments demonstrate promising outlook of using DMD to shape ultraviolet lasers for photocathode rf guns with various applications.

Laser Beam Shaping

NASA Astrophysics Data System (ADS)

Aït-Ameur, Kamel; Passilly, Nicolas; de Saint Denis, R.; Fromager, Michaël

2008-09-01

We consider the promising properties of very simple Diffractive Optical Elements (DOE) for reshaping the intensity profile of a laser beam. The first type of DOE that we have considered is a phase aperture which consists in a transparent plate with a circular relief introducing a π phase shift in the central region of the incident beam. The phase aperture is able to convert a Gaussian beam into a super-Gaussian, a ring-shaped or a doughnut profile. The second DOE that has been considered is an adjustable axicon able to transform a Gaussian laser beam into a dark hollow beam or a Bessel-Gauss beam. The desired conical geometry is obtained from a deformable mirror formed by a 2 inches, 0.25mm thick silicon wafer supported by a standard 2 inches optical mount. To achieve the adequate deformation a small metallic ball pushes the back of the mirror wafer. The realized shape is monitored with a Shack-Hartmann wave-front sensor and it is shown that conical shape cannot be achieved. Nevertheless, recorded wave fronts exhibit important third order spherical aberration able to achieve beam profile transformation as conical lenses.

Effects of volcano profile on dilute pyroclastic density currents: Numerical simulations

NASA Astrophysics Data System (ADS)

Doronzo, D. M.; Valentine, G. A.; Dellino, P.; de Tullio, M. D.

2012-04-01

Explosive activity and lava dome collapse at stratovolcanoes can lead to pyroclastic density currents (PDCs; mixtures of volcanic gas, air, and volcanic particles) that produce complex deposits and pose a hazard to surrounding populations. Two-dimensional numerical simulations of dilute PDCs (characterized by a turbulent suspended load and deposition through a bed load) are carried out with the Euler-Lagrange approach of multiphase physics. The fluid phase is modeled as a dusty gas (1.88 kg/m3 dense), and the solid phase is modeled as discrete particles (1 mm, 5 mm, and 10 mm; 1500 kg/m3 dense and irregularly-shaped), which are two-way coupled to the gas, i.e. they affect the fluid turbulence. The initial PDC, which enters a volcano domain 5 km long and 1.9 km high, has the following characteristics: thickness of 200 m, velocity of 20 m/s, temperature of 573 K, turbulence of 5 %, and sediment concentration of 3 % by volume. The actual physics of flow boundary zone is simulated at the PDC base, by monitoring the sediment flux toward the substrate, which acts through the flow boundary zone, and the grain-size distribution. Also, the PDC velocity and dynamic pressure are calculated. The simulations show that PDC transport, deposition, and hazard potential are sensitive to the shape of the volcano slope (profile) down which they flow. In particular, three generic volcano profiles, straight, concave-upward, and convex-upward are focused on. Dilute PDCs that flow down a constant slope gradually decelerate over the simulated run-out distance (5 km in the horizontal direction) due to a combination of sedimentation, which reduces the density of the PDC, and mixing with the atmosphere. However, dilute PDCs down a concave-upward slope accelerate high on the volcano flanks and have less sedimentation until they begin to decelerate over the shallow lower slopes. A convex-upward slope causes dilute PDCs to lose relatively more of their pyroclast load on the upper slopes of a volcano, and although they accelerate as they reach the lower, steeper slopes, the acceleration is reduced because of the upstream loss of pyroclasts (lower density contrast with the atmosphere). The dynamic pressure, a measure of the damage that can be caused by PDCs, reflects these complex relations. Details are found in Valentine et al. (2011). Reference Valentine G.A., Doronzo D.M., Dellino P., de Tullio M.D. (2011), Effects of volcano profile on dilute pyroclastic density currents: Numerical simulations, Geology, 39, 947-950.

Central safety factor and β N control on NSTX-U via beam power and plasma boundary shape modification, using TRANSP for closed loop simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyer, M. D.; Andre, R.; Gates, D. A.

The high-performance operational goals of NSTX-U will require development of advanced feedback control algorithms, including control of ßN and the safety factor profile. In this work, a novel approach to simultaneously controlling ßN and the value of the safety factor on the magnetic axis, q0, through manipulation of the plasma boundary shape and total beam power, is proposed. Simulations of the proposed scheme show promising results and motivate future experimental implementation and eventual integration into a more complex current profile control scheme planned to include actuation of individual beam powers, density, and loop voltage. As part of this work, amore » flexible framework for closed loop simulations within the high-fidelity code TRANSP was developed. The framework, used here to identify control-design-oriented models and to tune and test the proposed controller, exploits many of the predictive capabilities of TRANSP and provides a means for performing control calculations based on user-supplied data (controller matrices, target waveforms, etc.). The flexible framework should enable high-fidelity testing of a variety of control algorithms, thereby reducing the amount of expensive experimental time needed to implement new control algorithms on NSTX-U and other devices.« less

Central safety factor and βN control on NSTX-U via beam power and plasma boundary shape modification, using TRANSP for closed loop simulations

NASA Astrophysics Data System (ADS)

Boyer, M. D.; Andre, R.; Gates, D. A.; Gerhardt, S.; Goumiri, I. R.; Menard, J.

2015-05-01

The high-performance operational goals of NSTX-U will require development of advanced feedback control algorithms, including control of βN and the safety factor profile. In this work, a novel approach to simultaneously controlling βN and the value of the safety factor on the magnetic axis, q0, through manipulation of the plasma boundary shape and total beam power, is proposed. Simulations of the proposed scheme show promising results and motivate future experimental implementation and eventual integration into a more complex current profile control scheme planned to include actuation of individual beam powers, density, and loop voltage. As part of this work, a flexible framework for closed loop simulations within the high-fidelity code TRANSP was developed. The framework, used here to identify control-design-oriented models and to tune and test the proposed controller, exploits many of the predictive capabilities of TRANSP and provides a means for performing control calculations based on user-supplied data (controller matrices, target waveforms, etc). The flexible framework should enable high-fidelity testing of a variety of control algorithms, thereby reducing the amount of expensive experimental time needed to implement new control algorithms on NSTX-U and other devices.

High performance advanced tokamak regimes in DIII-D for next-step experiments

NASA Astrophysics Data System (ADS)

Greenfield, C. M.; Murakami, M.; Ferron, J. R.; Wade, M. R.; Luce, T. C.; Petty, C. C.; Menard, J. E.; Petrie, T. W.; Allen, S. L.; Burrell, K. H.; Casper, T. A.; DeBoo, J. C.; Doyle, E. J.; Garofalo, A. M.; Gorelov, I. A.; Groebner, R. J.; Hobirk, J.; Hyatt, A. W.; Jayakumar, R. J.; Kessel, C. E.; La Haye, R. J.; Jackson, G. L.; Lohr, J.; Makowski, M. A.; Pinsker, R. I.; Politzer, P. A.; Prater, R.; Strait, E. J.; Taylor, T. S.; West, W. P.; DIII-D Team

2004-05-01

Advanced Tokamak (AT) research in DIII-D [K. H. Burrell for the DIII-D Team, in Proceedings of the 19th Fusion Energy Conference, Lyon, France, 2002 (International Atomic Energy Agency, Vienna, 2002) published on CD-ROM] seeks to provide a scientific basis for steady-state high performance operation in future devices. These regimes require high toroidal beta to maximize fusion output and poloidal beta to maximize the self-driven bootstrap current. Achieving these conditions requires integrated, simultaneous control of the current and pressure profiles, and active magnetohydrodynamic stability control. The building blocks for AT operation are in hand. Resistive wall mode stabilization via plasma rotation and active feedback with nonaxisymmetric coils allows routine operation above the no-wall beta limit. Neoclassical tearing modes are stabilized by active feedback control of localized electron cyclotron current drive (ECCD). Plasma shaping and profile control provide further improvements. Under these conditions, bootstrap supplies most of the current. Steady-state operation requires replacing the remaining Ohmic current, mostly located near the half radius, with noninductive external sources. In DIII-D this current is provided by ECCD, and nearly stationary AT discharges have been sustained with little remaining Ohmic current. Fast wave current drive is being developed to control the central magnetic shear. Density control, with divertor cryopumps, of AT discharges with edge localized moding H-mode edges facilitates high current drive efficiency at reactor relevant collisionalities. A sophisticated plasma control system allows integrated control of these elements. Close coupling between modeling and experiment is key to understanding the separate elements, their complex nonlinear interactions, and their integration into self-consistent high performance scenarios. Progress on this development, and its implications for next-step devices, will be illustrated by results of recent experiment and simulation efforts.

Longitudinal bunch shaping of picosecond high-charge MeV electron beams

DOE PAGES

Beaudoin, B. L.; Thangaraj, J. C. T.; Edstrom, Jr., D.; ...

2016-10-20

With ever increasing demands for intensities in modern accelerators, the understanding of space-charge effects becomes crucial. Herein are presented measurements of optically shaped picosecond-long electron beams in a superconducting L-band linac over a wide range of charges, from 0.2 nC to 3.4 nC. At low charges, the shape of the electron beam is preserved, while at higher charge densities, modulations on the beam convert to energy modulations. Here, energy profile measurements using a spectrometer and time profile measurements using a streak camera reveal the dynamics of longitudinal space-charge on MeV-scale electron beams.

Core transport properties in JT-60U and JET identity plasmas

NASA Astrophysics Data System (ADS)

Litaudon, X.; Sakamoto, Y.; de Vries, P. C.; Salmi, A.; Tala, T.; Angioni, C.; Benkadda, S.; Beurskens, M. N. A.; Bourdelle, C.; Brix, M.; Crombé, K.; Fujita, T.; Futatani, S.; Garbet, X.; Giroud, C.; Hawkes, N. C.; Hayashi, N.; Hoang, G. T.; Hogeweij, G. M. D.; Matsunaga, G.; Nakano, T.; Oyama, N.; Parail, V.; Shinohara, K.; Suzuki, T.; Takechi, M.; Takenaga, H.; Takizuka, T.; Urano, H.; Voitsekhovitch, I.; Yoshida, M.; ITPA Transport Group; JT-60 Team; EFDA contributors, JET

2011-07-01

The paper compares the transport properties of a set of dimensionless identity experiments performed between JET and JT-60U in the advanced tokamak regime with internal transport barrier, ITB. These International Tokamak Physics Activity, ITPA, joint experiments were carried out with the same plasma shape, toroidal magnetic field ripple and dimensionless profiles as close as possible during the ITB triggering phase in terms of safety factor, normalized Larmor radius, normalized collision frequency, thermal beta, ratio of ion to electron temperatures. Similarities in the ITB triggering mechanisms and sustainment were observed when a good match was achieved of the most relevant normalized profiles except the toroidal Mach number. Similar thermal ion transport levels in the two devices have been measured in either monotonic or non-monotonic q-profiles. In contrast, differences between JET and JT-60U were observed on the electron thermal and particle confinement in reversed magnetic shear configurations. It was found that the larger shear reversal in the very centre (inside normalized radius of 0.2) of JT-60U plasmas allowed the sustainment of stronger electron density ITBs compared with JET. As a consequence of peaked density profile, the core bootstrap current density is more than five times higher in JT-60U compared with JET. Thanks to the bootstrap effect and the slightly broader neutral beam deposition, reversed magnetic shear configurations are self-sustained in JT-60U scenarios. Analyses of similarities and differences between the two devices address key questions on the validity of the usual assumptions made in ITER steady scenario modelling, e.g. a flat density profile in the core with thermal transport barrier? Such assumptions have consequences on the prediction of fusion performance, bootstrap current and on the sustainment of the scenario.

Dynamics of a gain-switched distributed feedback ridge waveguide laser in nanoseconds time scale under very high current injection conditions.

PubMed

Klehr, A; Wenzel, H; Brox, O; Schwertfeger, S; Staske, R; Erbert, G

2013-02-11

We present detailed experimental investigations of the temporal, spectral and spatial behavior of a gain-switched distributed feedback (DFB) laser emitting at a wavelength of 1064 nm. Gain-switching is achieved by injecting nearly rectangular shaped current pulses having a length of 50 ns and a very high amplitude up to 2.5 A. The repetition frequency is 200 kHz. The laser has a ridge waveguide (RW) for lateral waveguiding with a ridge width of 3 µm and a cavity length of 1.5 mm. Time resolved investigations show, depending on the amplitude of the current pulses, that the optical power exhibits different types of oscillatory behavior during the pulses, accompanied by changes in the lateral near field intensity profiles and optical spectra. Three different types of instabilities can be distinguished: mode beating with frequencies between 25 GHz and 30 GHz, switching between different lateral intensity profiles with a frequency of 0.4 GHz and self-sustained oscillations with a frequency of 4 GHz. The investigations are of great relevance for the utilization of gain-switched DFB-RW lasers as seed lasers for fiber laser systems and in other applications, which require a high optical power.

Magnetohydrodynamic simulations of noninductive helicity injection in the reversed-field pinch and tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sovinec, Carl R.

1995-11-01

Numerical computation is used to investigate resistive magnetohydrodynamic (MHD) fluctuations in the reversed-field pinch (RFP) and in tokamak-like configurations driven solely by direct current (DC) helicity injection. A Lundquist number (S) scan of RFP turbulence without plasma pressure produces the weak scaling of S -0.18 for the root-mean-square magnetic fluctuation level for 2.5x10 3≤S≤4x10 4. The temporal behavior of fluctuations and the reversal parameter becomes more regular as S is increased, acquiring a "sawtooth" shape at the largest value of S. Simulations with plasma pressure and anisotropic thermal conduction demonstrate energy transport resulting from parallel heat fluctuations. To investigate meansmore » of improving RFP energy confinement, three forms of current profile modification are tested. Radio frequency (RF) current drive is modeled with an auxiliary electron force, and linear stability calculations are used.« less

Cirrus microphysics and radiative transfer: Cloud field study on October 28, 1986

NASA Technical Reports Server (NTRS)

Kinne, Stefan; Ackerman, Thomas P.; Heymsfield, Andrew J.; Valero, Francisco P. J.; Sassen, Kenneth; Spinhirne, James D.

1990-01-01

The radiative properties of cirrus clouds present one of the unresolved problems in weather and climate research. Uncertainties in ice particle amount and size and, also, the general inability to model the single scattering properties of their usually complex particle shapes, prevent accurate model predictions. For an improved understanding of cirrus radiative effects, field experiments, as those of the Cirrus IFO of FIRE, are necessary. Simultaneous measurements of radiative fluxes and cirrus microphysics at multiple cirrus cloud altitudes allows the pitting of calculated versus measured vertical flux profiles; with the potential to judge current cirrus cloud modeling. Most of the problems in this study are linked to the inhomogeneity of the cloud field. Thus, only studies on more homogeneous cirrus cloud cases promises a possibility to improve current cirrus parameterizations. Still, the current inability to detect small ice particles will remain as a considerable handicap.

The Influence of Class II Division 2 Malocclusions on the Harmony of the Human Face Profile.

PubMed

Perović, Tatjana

2017-11-24

BACKGROUND Persons with class II division 2 malocclusion are characterized by a very specific dento-skeletal and soft-tissue profile (a profile in which a protruding nose and chin, retruding lips, concave and shortened lower third of the face, and gummy smile are dominant), which is the opposite of the currently modern profiles (convex profile of protruding lips and small chin). The aim of this research was to determine the differences in parameters of harmonies of facial profiles between persons with class II division 2 malocclusions and class I, and to establish the significance of those differences. MATERIAL AND METHODS For this study, 50 patients with class II division 2 malocclusions and 50 patients with class I were selected; profile photos were recorded and a photometric analysis was done: a type of profile according to Schwarz, the shape of a nose, the prominence of chin, biometrical field, the position of lips in relation to the tangent Sn-Pg, S-line (Steiner), E-line (Riketts) and a facial angle according to Arnett. RESULTS The significant differences in profiles of persons with class II division 2 compared to class I were: position and prominence of the chin, the position of the lower and upper lip in relation to the S-line, and smaller value of a facial angle in relation to persons with class I. CONCLUSIONS The differences seen in skeletal profiles were not associated with significant differences in the profiled facial contours of the examined groups. The compensatory role of the fullness of soft tissues of the lips is probably the reason why there were not significant deviations in all the examined parameters.

Method for wafer edge profile extraction using optical images obtained in edge defect inspection process

NASA Astrophysics Data System (ADS)

Okamoto, Hiroaki; Sakaguchi, Naoshi; Hayano, Fuminori

2010-03-01

It is becoming increasingly important to monitor wafer edge profiles in the immersion lithography era. A Nikon edge defect inspection tool acquires the circumferential optical images of the wafer edge during its inspection process. Nikon's unique illumination system and optics make it possible to then convert the brightness data of the captured images to quantifiable edge profile information. During this process the wafer's outer shape is also calculated. Test results show that even newly shipped bare wafers may not have a constant shape over 360 degree. In some cases repeated deformations with 90 degree pitch are observed.

Design and performance of a shape memory alloy-reinforced composite aerodynamic profile

NASA Astrophysics Data System (ADS)

Simpson, J. C.; Boller, C.

2008-04-01

Based on a shape memory alloy (SMA)-reinforced composite developed separately, the applicability of the composite has been demonstrated through realization of a realistically scaled aerodynamic profile of around 0.5 m span by 0.5 m root chord whose skins had been made from this composite. The design, manufacturing and assembly of the profile are described. The curved skins were manufactured with two layers of SMA wires integrated into the layup of aramid fibre prepregs. All SMA wires were connected such that they can be operated as individual sets of wires and at low voltages, similar to the conditions for electrical energy generation in a real aircraft. The profile was then mounted on a vibration test rig and excited by a shaker at its tip which allowed the dynamic performance of the profile to be validated under internal actuation conditions generated through the SMA wires.

Integration of tomato reproductive developmental landmarks and expression profiles, and the effect of SUN on fruit shape

PubMed Central

Xiao, Han; Radovich, Cheryll; Welty, Nicholas; Hsu, Jason; Li, Dongmei; Meulia, Tea; van der Knaap, Esther

2009-01-01

Background Universally accepted landmark stages are necessary to highlight key events in plant reproductive development and to facilitate comparisons among species. Domestication and selection of tomato resulted in many varieties that differ in fruit shape and size. This diversity is useful to unravel underlying molecular and developmental mechanisms that control organ morphology and patterning. The tomato fruit shape gene SUN controls fruit elongation. The most dramatic effect of SUN on fruit shape occurs after pollination and fertilization although a detailed investigation into the timing of the fruit shape change as well as gene expression profiles during critical developmental stages has not been conducted. Results We provide a description of floral and fruit development in a red-fruited closely related wild relative of tomato, Solanum pimpinellifolium accession LA1589. We use established and propose new floral and fruit landmarks to present a framework for tomato developmental studies. In addition, gene expression profiles of three key stages in floral and fruit development are presented, namely floral buds 10 days before anthesis (floral landmark 7), anthesis-stage flowers (floral landmark 10 and fruit landmark 1), and 5 days post anthesis fruit (fruit landmark 3). To demonstrate the utility of the landmarks, we characterize the tomato shape gene SUN in fruit development. SUN controls fruit shape predominantly after fertilization and its effect reaches a maximum at 8 days post-anthesis coinciding with fruit landmark 4 representing the globular embryo stage of seed development. The expression profiles of the NILs that differ at sun show that only 34 genes were differentially expressed and most of them at a less than 2-fold difference. Conclusion The landmarks for flower and fruit development in tomato were outlined and integrated with the effect of SUN on fruit shape. Although we did not identify many genes differentially expressed in the NILs that differ at the sun locus, higher or lower transcript levels for many genes involved in phytohormone biosynthesis or signaling as well as organ identity and patterning of tomato fruit were found between developmental time points. PMID:19422692

Overview of physics research on the TCV tokamak

NASA Astrophysics Data System (ADS)

Fasoli, A.; TCV Team

2009-10-01

The Tokamak à Configuration Variable (TCV) tokamak is equipped with high-power (4.5 MW), real-time-controllable EC systems and flexible shaping, and plays an important role in fusion research by broadening the parameter range of reactor relevant regimes, by investigating tokamak physics questions and by developing new control tools. Steady-state discharges are achieved, in which the current is entirely self-generated through the bootstrap mechanism, a fundamental ingredient for ITER steady-state operation. The discharge remains quiescent over several current redistribution times, demonstrating that a self-consistent, 'bootstrap-aligned' equilibrium state is possible. Electron internal transport barrier regimes sustained by EC current drive have also been explored. MHD activity is shown to be crucial in scenarios characterized by large and slow oscillations in plasma confinement, which in turn can be modified by small Ohmic current perturbations altering the barrier strength. In studies of the relation between anomalous transport and plasma shape, the observed dependences of the electron thermal diffusivity on triangularity (direct) and collisionality (inverse) are qualitatively reproduced by non-linear gyro-kinetic simulations and shown to be governed by TEM turbulence. Parallel SOL flows are studied for their importance for material migration. Flow profiles are measured using a reciprocating Mach probe by changing from lower to upper single-null diverted equilibria and shifting the plasmas vertically. The dominant, field-direction-dependent Pfirsch-Schlüter component is found to be in good agreement with theoretical predictions. A field-direction-independent component is identified and is consistent with flows generated by transient over-pressure due to ballooning-like interchange turbulence. Initial high-resolution infrared images confirm that ELMs have a filamentary structure, while fast, localized radiation measurements reveal that ELM activity first appears in the X-point region. Real time control techniques are currently being applied to EC multiple independent power supplies and beam launchers, e.g. to control the plasma current in fully non-inductive conditions, and the plasma elongation through current broadening by far-off-axis heating at constant shaping field.

Test of bootstrap current models using high- β p EAST-demonstration plasmas on DIII-D

DOE PAGES

Ren, Qilong; Lao, Lang L.; Garofalo, Andrea M.; ...

2015-01-12

Magnetic measurements together with kinetic profile and motional Stark effect measurements are used in full kinetic equilibrium reconstructions to test the Sauter and NEO bootstrap current models in a DIII-D high-more » $${{\\beta}_{\\text{p}}}$$ EAST-demonstration experiment. This aims at developing on DIII-D a high bootstrap current scenario to be extended on EAST for a demonstration of true steady-state at high performance and uses EAST-similar operational conditions: plasma shape, plasma current, toroidal magnetic field, total heating power and current ramp-up rate. It is found that the large edge bootstrap current in these high-$${{\\beta}_{\\text{p}}}$$ plasmas allows the use of magnetic measurements to clearly distinguish the two bootstrap current models. In these high collisionality and high-$${{\\beta}_{\\text{p}}}$$ plasmas, the Sauter model overpredicts the peak of the edge current density by about 30%, while the first-principle kinetic NEO model is in close agreement with the edge current density of the reconstructed equilibrium. Furthermore, these results are consistent with recent work showing that the Sauter model largely overestimates the edge bootstrap current at high collisionality.« less

Process based modeling of total longshore sediment transport

USGS Publications Warehouse

Haas, K.A.; Hanes, D.M.

2004-01-01

Waves, currents, and longshore sand transport are calculated locally as a function of position in the nearshore region using process based numerical models. The resultant longshore sand transport is then integrated across the nearshore to provide predictions of the total longshore transport of sand due to waves and longshore currents. Model results are in close agreement with the I1-P1 correlation described by Komar and Inman (1970) and the CERC (1984) formula. Model results also indicate that the proportionality constant in the I1-P1 formula depends weakly upon the sediment size, the shape of the beach profile, and the particular local sediment flux formula that is employed. Model results indicate that the various effects and influences of sediment size tend to cancel out, resulting in little overall dependence on sediment size.

The DIII-D Plasma Control System as a Scientific Research Tool

NASA Astrophysics Data System (ADS)

Hyatt, A. W.; Ferron, J. R.; Humphreys, D. A.; Leuer, J. A.; Walker, M. L.; Welander, A. S.

2006-10-01

The digital plasma control system (PCS) is an essential element of the DIII-D tokamak as a scientific research instrument, providing experimenters with real-time measurement and control of the plasma equilibrium, heating, current drive, transport, stability, and plasma-wall interactions. A wide range of sensors and actuators allow feedback control not only of global quantities such as discharge shape, plasma energy, and toroidal rotation, but also of non-axisymmetric magnetic fields and features of the internal profiles of temperature and current density. These diverse capabilities of the PCS improve the effectiveness of tokamak operation and enable unique physics experiments. We will present an overview of the PCS and the systems it controls and interacts with, and show examples of various plasma parameters controlled by the PCS and its actuators.

Electrochemical measurements on a droplet using gold microelectrodes

NASA Astrophysics Data System (ADS)

Jenabi, Amin; Souri, Asma; Rastkhadiv, Ali

2016-03-01

Facile methods of ion recognition are important for the fabrication of electronic tongue systems. In this work, we demonstrate performing pulsed conductometry on microliter electrolyte droplets dropped on gold microelectrodes vapor deposited on soda lime glass slides. A droplet is dropped between two microelectrodes when a voltage waveform from a preprogramed power supply is applied on them. The temporal variation of the electric current passing through the droplet is recorded, digitized and stored. The obtained data are compared with the database formed out of the previous experiences for the classification of the sample electrolytes. It is shown that the shape of the voltage waveform is the important parameter of the process. We devised a method for the optimization of the voltage waveform profile for obtaining the maximum of discriminating information from the recorded current variations.

Does the foveal shape influence the image formation in human eyes?

NASA Astrophysics Data System (ADS)

Frey, Katharina; Zimmerling, Beatrice; Scheibe, Patrick; Rauscher, Franziska G.; Reichenbach, Andreas; Francke, Mike; Brunner, Robert

2017-10-01

In human eyes, the maximum visual acuity correlates locally with the fovea, a shallow depression in the retina. Previous examinations have been reduced to simple geometrical fovea models derived from postmortem preparations and considering only a few superficial ray propagation aspects. In the current study, an extended and realistic analysis of ray-optical simulations for a comprehensive anatomical realistic eye model for the anterior part and realistic aspherical human foveal topographical profiles deduced from in vivo optical coherence tomography (OCT) are presented, and the refractive index step at the transition from vitreous to retinal tissue is taken into account. The optical effect of a commonly shaped (averaged) and an extraordinarily shaped foveal pit were both compared to the analysis of an assumed pure spherical boundary layer. The influence of the aperture size, wavelength, and incident angle on the spot size and shape, as well as the axial focal and lateral centroid position is investigated, and a lateral displacement of about 2 μm and an axial shift of the best focal position of less than 4 μm are found. These findings indicate only small optical effects that are laterally in the range of inter-receptor distances and axially less than the photoreceptor outer segment dimension.

On the line-shape analysis of Compton profiles and its application to neutron scattering

NASA Astrophysics Data System (ADS)

Romanelli, G.; Krzystyniak, M.

2016-05-01

Analytical properties of Compton profiles are used in order to simplify the analysis of neutron Compton scattering experiments. In particular, the possibility to fit the difference of Compton profiles is discussed as a way to greatly decrease the level of complexity of the data treatment, making the analysis easier, faster and more robust. In the context of the novel method proposed, two mathematical models describing the shapes of differenced Compton profiles are discussed: the simple Gaussian approximation for harmonic and isotropic local potential, and an analytical Gauss-Hermite expansion for an anharmonic or anisotropic potential. The method is applied to data collected by VESUVIO spectrometer at ISIS neutron and muon pulsed source (UK) on Copper and Aluminium samples at ambient and low temperatures.

Attractor neural networks with resource-efficient synaptic connectivity

NASA Astrophysics Data System (ADS)

Pehlevan, Cengiz; Sengupta, Anirvan

Memories are thought to be stored in the attractor states of recurrent neural networks. Here we explore how resource constraints interplay with memory storage function to shape synaptic connectivity of attractor networks. We propose that given a set of memories, in the form of population activity patterns, the neural circuit choses a synaptic connectivity configuration that minimizes a resource usage cost. We argue that the total synaptic weight (l1-norm) in the network measures the resource cost because synaptic weight is correlated with synaptic volume, which is a limited resource, and is proportional to neurotransmitter release and post-synaptic current, both of which cost energy. Using numerical simulations and replica theory, we characterize optimal connectivity profiles in resource-efficient attractor networks. Our theory explains several experimental observations on cortical connectivity profiles, 1) connectivity is sparse, because synapses are costly, 2) bidirectional connections are overrepresented and 3) are stronger, because attractor states need strong recurrence.

Thermal analysis of Bridgman-Stockbarger growth. [mercury cadmium telluride single crystals

NASA Technical Reports Server (NTRS)

Knopf, F. W.

1979-01-01

A thermal analysis of a cylindrical HgCdTe sample in a Bridgman-Stockbarger crystal growth configuration was conducted with emphasis on the thermal profile, interface shape and position, and the thermal gradients at the liquid-solid interface. Alloys of HgTe and CdTe with compositions approximating 20 percent CdTe, 80 percent HgTe were used. This composition results in a bandgap suited for the detection of 10.6 micron CO2 radiation. The sensitivity of the sample thermal characteristics to important growth parameters, such as thermal diffusivities, thermal conductivities, furnace temperature profile, ampoule dimensions, and growth velocity was assessed. Numerical techniques and associated computational models necessary to analyze the heat transfer process within the sample and the Bridgman-Stockbarger boundary conditions were developed. This thermal analysis mode was programmed in FORTRAN V, and is currently operational on the MSFC Univac 1100 system.

New vistas in refractive laser beam shaping with an analytic design approach

NASA Astrophysics Data System (ADS)

Duerr, Fabian; Thienpont, Hugo

2014-05-01

Many commercial, medical and scientific applications of the laser have been developed since its invention. Some of these applications require a specific beam irradiance distribution to ensure optimal performance. Often, it is possible to apply geometrical methods to design laser beam shapers. This common design approach is based on the ray mapping between the input plane and the output beam. Geometric ray mapping designs with two plano-aspheric lenses have been thoroughly studied in the past. Even though analytic expressions for various ray mapping functions do exist, the surface profiles of the lenses are still calculated numerically. In this work, we present an alternative novel design approach that allows direct calculation of the rotational symmetric lens profiles described by analytic functions. Starting from the example of a basic beam expander, a set of functional differential equations is derived from Fermat's principle. This formalism allows calculating the exact lens profiles described by Taylor series coefficients up to very high orders. To demonstrate the versatility of this new approach, two further cases are solved: a Gaussian to at-top irradiance beam shaping system, and a beam shaping system that generates a more complex dark-hollow Gaussian (donut-like) irradiance profile with zero intensity in the on-axis region. The presented ray tracing results confirm the high accuracy of all calculated solutions and indicate the potential of this design approach for refractive beam shaping applications.

Determination of the effect of source intensity profile on speckle contrast using coherent spatial frequency domain imaging

PubMed Central

Rice, Tyler B.; Konecky, Soren D.; Owen, Christopher; Choi, Bernard; Tromberg, Bruce J.

2012-01-01

Laser Speckle Imaging (LSI) is fast, noninvasive technique to image particle dynamics in scattering media such as biological tissue. While LSI measurements are independent of the overall intensity of the laser source, we find that spatial variations in the laser source profile can impact measured flow rates. This occurs due to differences in average photon path length across the profile, and is of significant concern because all lasers have some degree of natural Gaussian profile in addition to artifacts potentially caused by projecting optics. Two in vivo measurement are performed to show that flow rates differ based on location with respect to the beam profile. A quantitative analysis is then done through a speckle contrast forward model generated within a coherent Spatial Frequency Domain Imaging (cSFDI) formalism. The model predicts remitted speckle contrast as a function of spatial frequency, optical properties, and scattering dynamics. Comparison with experimental speckle contrast images were done using liquid phantoms with known optical properties for three common beam shapes. cSFDI is found to accurately predict speckle contrast for all beam shapes to within 5% root mean square error. Suggestions for improving beam homogeneity are given, including a widening of the natural beam Gaussian, proper diffusing glass spreading, and flat top shaping using microlens arrays. PMID:22741080

A conceptual model for the development of pristine drainage systems during exhumation of metamorphic core complexes

NASA Astrophysics Data System (ADS)

Trost, Georg; Neubauer, Franz; Robl, Jörg

2017-04-01

Metamorphic core complexes (MCCs) are defined as large scale geological features of domal shape. The essential characteristic comprises metamorphic rocks, which have been exhumed from lower crustal levels and now are exposed to the surface. The updoming process occurs at different tectonic settings of high strain zones initially exposing pristine gently dipping fault planes to Earth's surface. Consequently, the dome shape highly influences the type of adaption of the drainage systems to the active landforms. However, drainage systems and their characteristic metrics in regions shaped by MCCs have only been sparsely investigated and were not examined regarding the distinction between different MCC-types (A-type, B-type, C-type). In this study we investigate the drainage patterns of MCCs formed by different tectonic settings and build up a conceptual model for the development of the drainage systems under these conditions. We apply the χ-method to detect variations in uplift, as well as spatial unconformities in the drainage patterns. The χ-method is a mathematical approach to transform stream longitudinal profiles to the χ space where the slope of steady state profiles is solely dependent on uplift rate and bedrock erodibility. From this transformation we calculate color-coded χ-maps and χ-profiles of the main streams draining the MCCs. The applied method allows the interpretation of channel metrics in terms of (a) spatial gradients in uplift rate and (b) the time dependent evolution of drainage divides including drainage divide migration. Our results show a high variation in the shape and greatest elevation of the χ-profiles. This indicates the migration of active uplift zones along the dome axes. Even though only MCCs younger than Miocene age are investigated, the shape of the χ-profiles clearly points to different development stages of these areas. K-profiles plotted over the detachment underlying an active updoming process show concave shaped χ-profiles. In contrast, χ-profiles plotted over the detachments coined by long-term erosional processes tend to preserve prominent knickpoints in linearly proceeding profiles. Additionally, the migration of the watersheds indicates lateral extension of the domes, potentially influenced by rolling hinges. MCCs subjected to active uplift show proceeding stream piracy of streams following tectonically induced lineaments. Drainage systems have systematically deflected streams at the edges of the dome structures. The deflections can be especially observed at A-type domes (dome axis oriented parallel to the direction of extension). We conclude that our observations can be explained by the Rolling-Hinge model for MCC-formation. This model is applicable for all types of MCCs and gives the mechanical basis for the updoming process and such for the first stages of drainage development. Some of the observed features are dedicated to ongoing erosional processes and hence represent later phases of MCC development.

Middle atmosphere electrical energy coupling

NASA Technical Reports Server (NTRS)

Hale, L. C.

1989-01-01

The middle atmosphere (MA) has long been known as an absorber of radio waves, and as a region of nonlinear interactions among waves. The region of highest transverse conductivity near the top of the MA provides a common return for global thunderstorm, auroral Birkeland, and ionospheric dynamo currents, with possibilities for coupling among them. Their associated fields and other transverse fields map to lower altitudes depending on scale size. Evidence now exists for motion-driven aerosol generators, and for charge trapped at the base of magnetic field lines, both capable of producing large MA electric fields. Ionospheric Maxwell currents (curl H) parallel to the magnetic field appear to map to lower altitudes, with rapidly time-varying components appearing as displacement currents in the stratosphere. Lightning couples a (primarily ELF and ULF) current transient to the ionosphere and magnetosphere whose wave shape is largely dependent on the MA conductivity profile. Electrical energy is of direct significance mainly in the upper MA, but electrodynamic transport of minor constituents such as smoke particles or CN may be important at other altitudes.

Simulation of the electric potential and plasma generation coupling in magnetron sputtering discharges

NASA Astrophysics Data System (ADS)

Trieschmann, Jan; Krueger, Dennis; Schmidt, Frederik; Brinkmann, Ralf Peter; Mussenbrock, Thomas

2016-09-01

Magnetron sputtering typically operated at low pressures below 1 Pa is a widely applied deposition technique. For both, high power impulse magnetron sputtering (HiPIMS) as well as direct current magnetron sputtering (dcMS) the phenomenon of rotating ionization zones (also referred to as spokes) has been observed. A distinct spatial profile of the electric potential has been associated with the latter, giving rise to low, mid, and high energy groups of ions observed at the substrate. The adherent question of which mechanism drives this process is still not fully understood. This query is approached using Monte Carlo simulations of the heavy particle (i.e., ions and neutrals) transport consistently coupled to a pre-specified electron density profile via the intrinsic electric field. The coupling between the plasma generation and the electric potential, which establishes correspondingly, is investigated. While the system is observed to strive towards quasi-neutrality, distinct mechanisms governing the shape of the electric potential profile are identified. This work is supported by the German Research Foundation (DFG) in the frame of the transregional collaborative research centre TRR 87.

Einasto profiles and the dark matter power spectrum

NASA Astrophysics Data System (ADS)

Ludlow, Aaron D.; Angulo, Raúl E.

2017-02-01

We study the mass accretion histories (MAHs) and density profiles of dark matter haloes using N-body simulations of self-similar gravitational clustering from scale-free power spectra, P(k) ∝ kn. We pay particular attention to the density profile curvature, which we characterize using the shape parameter, α, of an Einasto profile. In agreement with previous findings, our results suggest that, despite vast differences in their MAHs, the density profiles of virialized haloes are remarkably alike. Nonetheless, clear departures from self-similarity are evident: For a given spectral index, α increases slightly but systematically with `peak height', ν ≡ δsc/σ(M, z), regardless of mass or redshift. More importantly, however, the `α-ν' relation depends on n: The steeper the initial power spectrum, the more gradual the curvature of both the mean MAHs and mean density profiles. These results are consistent with previous findings connecting the shapes of halo mass profiles and MAHs, and imply that dark matter haloes are not structurally self-similar but, through the merger history, retain a memory of the linear density field from which they form.

Design of relative motion and attitude profiles for three-dimensional resident space object imaging with a laser rangefinder

NASA Astrophysics Data System (ADS)

Nayak, M.; Beck, J.; Udrea, B.

This paper focuses on the aerospace application of a single beam laser rangefinder (LRF) for 3D imaging, shape detection, and reconstruction in the context of a space-based space situational awareness (SSA) mission scenario. The primary limitation to 3D imaging from LRF point clouds is the one-dimensional nature of the single beam measurements. A method that combines relative orbital motion and scanning attitude motion to generate point clouds has been developed and the design and characterization of multiple relative motion and attitude maneuver profiles are presented. The target resident space object (RSO) has the shape of a generic telecommunications satellite. The shape and attitude of the RSO are unknown to the chaser satellite however, it is assumed that the RSO is un-cooperative and has fixed inertial pointing. All sensors in the metrology chain are assumed ideal. A previous study by the authors used pure Keplerian motion to perform a similar 3D imaging mission at an asteroid. A new baseline for proximity operations maneuvers for LRF scanning, based on a waypoint adaptation of the Hill-Clohessy-Wiltshire (HCW) equations is examined. Propellant expenditure for each waypoint profile is discussed and combinations of relative motion and attitude maneuvers that minimize the propellant used to achieve a minimum required point cloud density are studied. Both LRF strike-point coverage and point cloud density are maximized; the capability for 3D shape registration and reconstruction from point clouds generated with a single beam LRF without catalog comparison is proven. Next, a method of using edge detection algorithms to process a point cloud into a 3D modeled image containing reconstructed shapes is presented. Weighted accuracy of edge reconstruction with respect to the true model is used to calculate a qualitative “ metric” that evaluates effectiveness of coverage. Both edge recognition algorithms and the metric are independent of point cloud densit- , therefore they are utilized to compare the quality of point clouds generated by various attitude and waypoint command profiles. The RSO model incorporates diverse irregular protruding shapes, such as open sensor covers, instrument pods and solar arrays, to test the limits of the algorithms. This analysis is used to mathematically prove that point clouds generated by a single-beam LRF can achieve sufficient edge recognition accuracy for SSA applications, with meaningful shape information extractable even from sparse point clouds. For all command profiles, reconstruction of RSO shapes from the point clouds generated with the proposed method are compared to the truth model and conclusions are drawn regarding their fidelity.

Arachidonic and oleic acid exert distinct effects on the DNA methylome

PubMed Central

Silva-Martínez, Guillermo A.; Rodríguez-Ríos, Dalia; Alvarado-Caudillo, Yolanda; Vaquero, Alejandro; Esteller, Manel; Carmona, F. Javier; Moran, Sebastian; Nielsen, Finn C.; Wickström-Lindholm, Marie; Wrobel, Katarzyna; Wrobel, Kazimierz; Barbosa-Sabanero, Gloria; Zaina, Silvio; Lund, Gertrud

2016-01-01

ABSTRACT Abnormal fatty acid metabolism and availability are landmarks of metabolic diseases, which in turn are associated with aberrant DNA methylation profiles. To understand the role of fatty acids in disease epigenetics, we sought DNA methylation profiles specifically induced by arachidonic (AA) or oleic acid (OA) in cultured cells and compared those with published profiles of normal and diseased tissues. THP-1 monocytes were stimulated with AA or OA and analyzed using Infinium HumanMethylation450 BeadChip (Illumina) and Human Exon 1.0 ST array (Affymetrix). Data were corroborated in mouse embryonic fibroblasts. Comparisons with publicly available data were conducted by standard bioinformatics. AA and OA elicited a complex response marked by a general DNA hypermethylation and hypomethylation in the 1–200 μM range, respectively, with a maximal differential response at the 100 μM dose. The divergent response to AA and OA was prominent within the gene body of target genes, where it correlated positively with transcription. AA-induced DNA methylation profiles were similar to the corresponding profiles described for palmitic acid, atherosclerosis, diabetes, obesity, and autism, but relatively dissimilar from OA-induced profiles. Furthermore, human atherosclerosis grade-associated DNA methylation profiles were significantly enriched in AA-induced profiles. Biochemical evidence pointed to β-oxidation, PPAR-α, and sirtuin 1 as important mediators of AA-induced DNA methylation changes. In conclusion, AA and OA exert distinct effects on the DNA methylome. The observation that AA may contribute to shape the epigenome of important metabolic diseases, supports and expands current diet-based therapeutic and preventive efforts. PMID:27088456

Experimental evaluation of x-ray acoustic computed tomography for radiotherapy dosimetry applications.

PubMed

Hickling, Susannah; Lei, Hao; Hobson, Maritza; Léger, Pierre; Wang, Xueding; El Naqa, Issam

2017-02-01

The aim of this work was to experimentally demonstrate the feasibility of x-ray acoustic computed tomography (XACT) as a dosimetry tool in a clinical radiotherapy environment. The acoustic waves induced following a single pulse of linear accelerator irradiation in a water tank were detected with an immersion ultrasound transducer. By rotating the collimator and keeping the transducer stationary, acoustic signals at varying angles surrounding the field were detected and reconstructed to form an XACT image. Simulated XACT images were obtained using a previously developed simulation workflow. Profiles extracted from experimental and simulated XACT images were compared to profiles measured with an ion chamber. A variety of radiation field sizes and shapes were investigated. XACT images resembling the geometry of the delivered radiation field were obtained for fields ranging from simple squares to more complex shapes. When comparing profiles extracted from simulated and experimental XACT images of a 4 cm × 4 cm field, 97% of points were found to pass a 3%/3 mm gamma test. Agreement between simulated and experimental XACT images worsened when comparing fields with fine details. Profiles extracted from experimental XACT images were compared to profiles obtained through clinical ion chamber measurements, confirming that the intensity of XACT images is related to deposited radiation dose. Seventy-seven percent of the points in a profile extracted from an experimental XACT image of a 4 cm × 4 cm field passed a 7%/4 mm gamma test when compared to an ion chamber measured profile. In a complicated puzzle-piece shaped field, 86% of the points in an XACT extracted profile passed a 7%/4 mm gamma test. XACT images with intensity related to the spatial distribution of deposited dose in a water tank were formed for a variety of field sizes and shapes. XACT has the potential to be a useful tool for absolute, relative and in vivo dosimetry. © 2016 American Association of Physicists in Medicine.

Forming three-dimensional closed shapes from two-dimensional soft ribbons by controlled buckling

PubMed Central

Aoki, Michio

2018-01-01

Conventional manufacturing techniques—moulding, machining and casting—exist to produce three-dimensional (3D) shapes. However, these industrial processes are typically geared for mass production and are not directly applicable to residential settings, where inexpensive and versatile tools are desirable. Moreover, those techniques are, in general, not adequate to process soft elastic materials. Here, we introduce a new concept of forming 3D closed hollow shapes from two-dimensional (2D) elastic ribbons by controlled buckling. We numerically and experimentally characterize how the profile and thickness of the ribbon determine its buckled shape. We find a 2D master profile with which various elliptical 3D shapes can be formed. More complex natural and artificial hollow shapes, such as strawberry, hourglass and wheel, can also be achieved via strategic design and pattern engraving on the ribbons. The nonlinear response of the post-buckling regime is rationalized through finite-element analysis, which shows good quantitative agreement with experiments. This robust fabrication should complement conventional techniques and provide a rich arena for future studies on the mechanics and new applications of elastic hollow structures. PMID:29515894

Forming three-dimensional closed shapes from two-dimensional soft ribbons by controlled buckling

NASA Astrophysics Data System (ADS)

Aoki, Michio; Juang, Jia-Yang

2018-02-01

Conventional manufacturing techniques-moulding, machining and casting-exist to produce three-dimensional (3D) shapes. However, these industrial processes are typically geared for mass production and are not directly applicable to residential settings, where inexpensive and versatile tools are desirable. Moreover, those techniques are, in general, not adequate to process soft elastic materials. Here, we introduce a new concept of forming 3D closed hollow shapes from two-dimensional (2D) elastic ribbons by controlled buckling. We numerically and experimentally characterize how the profile and thickness of the ribbon determine its buckled shape. We find a 2D master profile with which various elliptical 3D shapes can be formed. More complex natural and artificial hollow shapes, such as strawberry, hourglass and wheel, can also be achieved via strategic design and pattern engraving on the ribbons. The nonlinear response of the post-buckling regime is rationalized through finite-element analysis, which shows good quantitative agreement with experiments. This robust fabrication should complement conventional techniques and provide a rich arena for future studies on the mechanics and new applications of elastic hollow structures.

Total magnitudes of Virgo galaxies - III. Scale errors in the Reference Catalogue of Bright Galaxies T system and light-profile distortion by resolution-degrading and differential-distance effects

NASA Astrophysics Data System (ADS)

Young, Christopher Ke-shih

2004-11-01

We investigate the BT magnitude scales of the Second and Third Reference Catalogues of Bright Galaxies, finding both scales to be reasonably reliable for 11.5 <~Bt<~ 14.0. However, large-scale errors of 0.26 and 0.24mag per unit mag interval respectively are uncovered for early-type galaxies at the bright ends, whilst even larger ones of 0.74 and 0.36mag per unit mag interval are found for galaxies of all morphological types at the faint ends. We attribute this situation to several effects already discussed by Young et al. and Young (Paper I), including the application of relatively inflexible growth-curve models that are only in a few specific cases appropriate to the galaxies concerned. Of particular interest to this study though, we find that the apparent profile shapes of giant galaxies in the Virgo direction of cz < 15000 km s-1 tend to be less centrally concentrated the greater their distance. This demonstrates that even for relatively nearby galaxies, the distortion of the overall shapes of light profiles by resolution-degrading effects such as seeing and data smoothing, as originally predicted and modelled by Young & Currie and Young et al., is a significant effect. It is, therefore, not good practice simply to extrapolate the profiles of galaxies of identical intrinsic size and intrinsic profile shape (i.e. identical morphology) by means of the same growth-curve model, unless the galaxies are known a priori to be at the same distance and unless their photometry is of the same angular resolution. We also investigate the total-magnitude scale of the catalogue of photometric types of Prugniel & Héraudeau, finding it to be much more reliable than the BT one. However, we argue that photometric type is really a measure of apparent profile shape (i.e. intrinsic profile shape after scale reduction on account of distance followed by convolution with a seeing disc and often a smoothing function as well). Strictly, it should therefore only be applicable to comparisons between galaxies that are already known to be at similar distances provided that their photometry is also of similar angular resolution. Clearly, this must complicate attempts to construct quantitative morphological classification schemes for galaxies.

Pulse generation and preamplification for long pulse beamlines of Orion laser facility.

PubMed

Hillier, David I; Winter, David N; Hopps, Nicholas W

2010-06-01

We describe the pulse generation, shaping, and preamplification system for the nanosecond beamlines of the Orion laser facility. The system generates shaped laser pulses of up to approximately 1 J of 100 ps-5 ns duration with a programmable temporal profile. The laser has a 30th-power supergaussian spatial profile and is diffraction limited. The system is capable of imposing 2D smoothing by spectral dispersion upon the beam, which will produce a nonuniformity of 10% rms at the target.

Numerical investigation of galloping instabilities in Z-shaped profiles.

PubMed

Gomez, Ignacio; Chavez, Miguel; Alonso, Gustavo; Valero, Eusebio

2014-01-01

Aeroelastic effects are relatively common in the design of modern civil constructions such as office blocks, airport terminal buildings, and factories. Typical flexible structures exposed to the action of wind are shading devices, normally slats or louvers. A typical cross-section for such elements is a Z-shaped profile, made out of a central web and two-side wings. Galloping instabilities are often determined in practice using the Glauert-Den Hartog criterion. This criterion relies on accurate predictions of the dependence of the aerodynamic force coefficients with the angle of attack. The results of a parametric analysis based on a numerical analysis and performed on different Z-shaped louvers to determine translational galloping instability regions are presented in this paper. These numerical analysis results have been validated with a parametric analysis of Z-shaped profiles based on static wind tunnel tests. In order to perform this validation, the DLR TAU Code, which is a standard code within the European aeronautical industry, has been used. This study highlights the focus on the numerical prediction of the effect of galloping, which is shown in a visible way, through stability maps. Comparisons between numerical and experimental data are presented with respect to various meshes and turbulence models.

Estimation of lung shunt fraction from simultaneous fluoroscopic and nuclear images

NASA Astrophysics Data System (ADS)

van der Velden, Sandra; Bastiaannet, Remco; Braat, Arthur J. A. T.; Lam, Marnix G. E. H.; Viergever, Max A.; de Jong, Hugo W. A. M.

2017-11-01

Radioembolisation with yttrium-90 (90Y) is increasingly used as a treatment of unresectable liver malignancies. For safety, a scout dose of technetium-99m macroaggregated albumin (99mTc-MAA) is used prior to the delivery of the therapeutic activity to mimic the deposition of 90Y. One-day procedures are currently limited by the lack of nuclear images in the intervention room. To cope with this limitation, an interventional simultaneous fluoroscopic and nuclear imaging device is currently being developed. The purpose of this simulation study was to evaluate the accuracy of estimating the lung shunt fraction (LSF) of the scout dose in the intervention room with this device and compare it against current clinical methods. Methods: A male and female XCAT phantom, both with two respiratory profiles, were used to simulate various LSFs resulting from a scout dose of 150 MBq 99mTc-MAA. Hybrid images were Monte Carlo simulated for breath-hold (5 s) and dynamic breathing (10 frames of 0.5 s) acquisitions. Nuclear images were corrected for attenuation with the fluoroscopic image and for organ overlap effects using a pre-treatment CT-scan. For comparison purposes, planar scintigraphy and mobile gamma camera images (both 300 s acquisition time) were simulated. Estimated LSFs were evaluated for all methods and compared to the phantom ground truth. Results: In the clinically relevant range of 10-20% LSF, hybrid imaging overestimated LSF with approximately 2 percentage points (pp) and 3 pp for the normal and irregular breathing phantoms, respectively. After organ overlap correction, LSF was estimated with a more constant error. Errors in planar scintigraphy and mobile gamma camera imaging were more dependent on LSF, body shape and breathing profile. Conclusion: LSF can be estimated with a constant minor error with a hybrid imaging device. Estimated LSF is highly dependent on true LSF, body shape and breathing pattern when estimated with current clinical methods. The hybrid imaging device is capable of accurately estimating LSF within a few seconds in an interventional setting.

The implementation of non-Voigt line profiles in the HITRAN database: H2 case study

NASA Astrophysics Data System (ADS)

Wcisło, P.; Gordon, I. E.; Tran, H.; Tan, Y.; Hu, S.-M.; Campargue, A.; Kassi, S.; Romanini, D.; Hill, C.; Kochanov, R. V.; Rothman, L. S.

2016-07-01

Experimental capabilities of molecular spectroscopy and its applications nowadays require a sub-percent or even sub-per mille accuracy of the representation of the shapes of molecular transitions. This implies the necessity of using more advanced line-shape models which are characterized by many more parameters than a simple Voigt profile. It is a great challenge for modern molecular spectral databases to store and maintain the extended set of line-shape parameters as well as their temperature dependences. It is even more challenging to reliably retrieve these parameters from experimental spectra over a large range of pressures and temperatures. In this paper we address this problem starting from the case of the H2 molecule for which the non-Voigt line-shape effects are exceptionally pronounced. For this purpose we reanalyzed the experimental data reported in the literature. In particular, we performed detailed line-shape analysis of high-quality spectra obtained with cavity-enhanced techniques. We also report the first high-quality cavity-enhanced measurement of the H2 fundamental vibrational mode. We develop a correction to the Hartmann-Tran profile (HTP) which adjusts the HTP to the particular model of the velocity-changing collisions. This allows the measured spectra to be better represented over a wide range of pressures. The problem of storing the HTP parameters in the HITRAN database together with their temperature dependences is also discussed.

Laser beam-profile impression and target thickness impact on laser-accelerated protons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schollmeier, M.; Harres, K.; Nuernberg, F.

Experimental results on the influence of the laser focal spot shape onto the beam profile of laser-accelerated protons from gold foils are reported. The targets' microgrooved rear side, together with a stack of radiochromic films, allowed us to deduce the energy-dependent proton source-shape and size, respectively. The experiments show, that shape and size of the proton source depend only weakly on target thickness as well as shape of the laser focus, although they strongly influence the proton's intensity distribution. It was shown that the laser creates an electron beam that closely follows the laser beam topology, which is maintained duringmore » the propagation through the target. Protons are then accelerated from the rear side with an electron created electric field of a similar shape. Simulations with the Sheath-Accelerated Beam Ray-tracing for IoN Analysis code SABRINA, which calculates the proton distribution in the detector for a given laser-beam profile, show that the electron distribution during the transport through a thick target (50 {mu}m Au) is only modified due to multiple small angle scattering. Thin targets (10 {mu}m) show large source sizes of over 100 {mu}m diameter for 5 MeV protons, which cannot be explained by multiple scattering only and are most likely the result of refluxing electrons.« less

One-step fabrication of nanostructure-covered microstructures using selective aluminum anodization based on non-uniform electric field

NASA Astrophysics Data System (ADS)

Park, Yong Min; Kim, Byeong Hee; Seo, Young Ho

2016-06-01

This paper presents a selective aluminum anodization technique for the fabrication of microstructures covered by nanoscale dome structures. It is possible to fabricate bulging microstructures, utilizing the different growth rates of anodic aluminum oxide in non-uniform electric fields, because the growth rate of anodic aluminum oxide depends on the intensity of electric field, or current density. After anodizing under a non-uniform electric field, bulging microstructures covered by nanostructures were fabricated by removing the residual aluminum layer. The non-uniform electric field induced by insulative micropatterns was estimated by computational simulations and verified experimentally. Utilizing computational simulations, the intensity profile of the electric field was calculated according to the ratio of height and width of the insulative micropatterns. To compare computational simulation results and experimental results, insulative micropatterns were fabricated using SU-8 photoresist. The results verified that the shape of the bottom topology of anodic alumina was strongly dependent on the intensity profile of the applied electric field, or current density. The one-step fabrication of nanostructure-covered microstructures can be applied to various fields, such as nano-biochip and nano-optics, owing to its simplicity and cost effectiveness.

Three-dimensional modeling of a negative ion source with a magnetic filter: impact of biasing the plasma electrode on the plasma asymmetry

NASA Astrophysics Data System (ADS)

Fubiani, G.; Boeuf, J. P.

2015-10-01

The effect on the plasma characteristics of biasing positively the plasma electrode (PE) in negative ion sources with a magnetic filter is analysed using a 3D particle-in-cell model with Monte-Carlo collisions (PIC-MCC). We specialize to the one driver (i.e. one inductively coupled radio-frequency discharge) BATMAN negative ion source and the 4-drivers (large volume) ELISE device. Both are ITER prototype high power tandem-type negative ion sources developed for the neutral beam injector (NBI) system. The plasma is generated in the driver and diffuses inside the second chamber which is magnetized. Asymmetric plasma profiles originate from the formation of an electric field transverse to the electron current flowing through the magnetic filter (Hall effect). The model shows that the importance of the asymmetry increases with the PE bias potential, i.e. with the electron flow from the driver to the extraction region and depends on the shape of the magnetic filter field. We find that although the plasma density and potential profiles may be more or less asymmetric depending on the filter field configuration, the electron current to the plasma grid is always strongly asymmetric.

Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.

PubMed

Song, Hongjun; Wang, Yi; Pant, Kapil

2013-01-01

This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (<0.5% relative error). An extensive parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space.

Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow

PubMed Central

Song, Hongjun; Wang, Yi; Pant, Kapil

2012-01-01

This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (<0.5% relative error). An extensive parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space. PMID:23554584

The use of generalised additive models (GAM) in dentistry.

PubMed

Helfenstein, U; Steiner, M; Menghini, G

1997-12-01

Ordinary multiple regression and logistic multiple regression are widely applied statistical methods which allow a researcher to 'explain' or 'predict' a response variable from a set of explanatory variables or predictors. In these models it is usually assumed that quantitative predictors such as age enter linearly into the model. During recent years these methods have been further developed to allow more flexibility in the way explanatory variables 'act' on a response variable. The methods are called 'generalised additive models' (GAM). The rigid linear terms characterising the association between response and predictors are replaced in an optimal way by flexible curved functions of the predictors (the 'profiles'). Plotting the 'profiles' allows the researcher to visualise easily the shape by which predictors 'act' over the whole range of values. The method facilitates detection of particular shapes such as 'bumps', 'U-shapes', 'J-shapes, 'threshold values' etc. Information about the shape of the association is not revealed by traditional methods. The shapes of the profiles may be checked by performing a Monte Carlo simulation ('bootstrapping'). After the presentation of the GAM a relevant case study is presented in order to demonstrate application and use of the method. The dependence of caries in primary teeth on a set of explanatory variables is investigated. Since GAMs may not be easily accessible to dentists, this article presents them in an introductory condensed form. It was thought that a nonmathematical summary and a worked example might encourage readers to consider the methods described. GAMs may be of great value to dentists in allowing visualisation of the shape by which predictors 'act' and obtaining a better understanding of the complex relationships between predictors and response.

Prediction of Process-Induced Distortions in L-Shaped Composite Profiles Using Path-Dependent Constitutive Law

NASA Astrophysics Data System (ADS)

Ding, Anxin; Li, Shuxin; Wang, Jihui; Ni, Aiqing; Sun, Liangliang; Chang, Lei

2016-10-01

In this paper, the corner spring-in angles of AS4/8552 L-shaped composite profiles with different thicknesses are predicted using path-dependent constitutive law with the consideration of material properties variation due to phase change during curing. The prediction accuracy mainly depends on the properties in the rubbery and glassy states obtained by homogenization method rather than experimental measurements. Both analytical and finite element (FE) homogenization methods are applied to predict the overall properties of AS4/8552 composite. The effect of fiber volume fraction on the properties is investigated for both rubbery and glassy states using both methods. And the predicted results are compared with experimental measurements for the glassy state. Good agreement is achieved between the predicted results and available experimental data, showing the reliability of the homogenization method. Furthermore, the corner spring-in angles of L-shaped composite profiles are measured experimentally and the reliability of path-dependent constitutive law is validated as well as the properties prediction by FE homogenization method.

Information Processing Research

DTIC Science & Technology

1979-06-01

quantitative shape recovery. For the qualitative shape recovery we use a model of the Origami world (Kanade, 1978), together with edge profiles of...Workshop. Carnegie-Mellon University, Computer Science Department, Pittsburgh, PA, November, 1978. Kanade, T. A theory of origami world. Technical

Omokage search: shape similarity search service for biomolecular structures in both the PDB and EMDB.

PubMed

Suzuki, Hirofumi; Kawabata, Takeshi; Nakamura, Haruki

2016-02-15

Omokage search is a service to search the global shape similarity of biological macromolecules and their assemblies, in both the Protein Data Bank (PDB) and Electron Microscopy Data Bank (EMDB). The server compares global shapes of assemblies independent of sequence order and number of subunits. As a search query, the user inputs a structure ID (PDB ID or EMDB ID) or uploads an atomic model or 3D density map to the server. The search is performed usually within 1 min, using one-dimensional profiles (incremental distance rank profiles) to characterize the shapes. Using the gmfit (Gaussian mixture model fitting) program, the found structures are fitted onto the query structure and their superimposed structures are displayed on the Web browser. Our service provides new structural perspectives to life science researchers. Omokage search is freely accessible at http://pdbj.org/omokage/. © The Author 2015. Published by Oxford University Press.

Identification and control of a multizone crystal growth furnace

NASA Technical Reports Server (NTRS)

Batur, C.; Sharpless, R. B.; Duval, W. M. B.; Rosenthal, B. N.; Singh, N. B.

1992-01-01

This paper presents an intelligent adaptive control system for the control of a solid-liquid interface of a crystal while it is growing via directional solidification inside a multizone transparent furnace. The task of the process controller is to establish a user-specified axial temperature profile and to maintain a desirable interface shape. Both single-input-single-output and multi-input-multi-output adaptive pole placement algorithms have been used to control the temperature. Also described is an intelligent measurement system to assess the shape of the crystal while it is growing. A color video imaging system observes the crystal in real time and determines the position and the shape of the interface. This information is used to evaluate the crystal growth rate, and to analyze the effects of translational velocity and temperature profiles on the shape of the interface. Creation of this knowledge base is the first step to incorporate image processing into furnace control.

Electrostatic potential profiles of molecular conductors

NASA Astrophysics Data System (ADS)

Liang, G. C.; Ghosh, A. W.; Paulsson, M.; Datta, S.

2004-03-01

The electrostatic potential across a short ballistic molecular conductor depends sensitively on the geometry of its environment, and can affect its conduction significantly by influencing its energy levels and wave functions. We illustrate some of the issues involved by evaluating the potential profiles for a conducting gold wire and an aromatic phenyl dithiol molecule in various geometries. The potential profile is obtained by solving Poisson’s equation with boundary conditions set by the contact electrochemical potentials and coupling the result self-consistently with a nonequilibrium Green’s function formulation of transport. The overall shape of the potential profile (ramp versus flat) depends on the feasibility of transverse screening of electric fields. Accordingly, the screening is better for a thick wire, a multiwalled nanotube, or a close-packed self-assembled monolayer, in comparison to a thin wire, a single-walled nanotube, or an isolated molecular conductor. The electrostatic potential further governs the alignment or misalignment of intramolecular levels, which can strongly influence the molecular current voltage (I V) characteristic. An external gate voltage can modify the overall potential profile, changing the I V characteristic from a resonant conducting to a saturating one. The degree of saturation and gate modulation depends on the availability of metal-induced-gap states and on the electrostatic gate control parameter set by the ratio of the gate oxide thickness to the channel length.

WE-AB-BRB-10: Filmless QA of CyberKnife MLC-Collimated and Iris-Collimated Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gersh, J; Spectrum Medical Physics, LLC, Greenville, SC

Purpose: Current methods of CK field shape QA is based on the use of radiochromic film. Though accurate results can be attained, these methods are prone to error, time consuming, and expensive. The techniques described herein perform similar QA using the FOIL Detector (Field, Output, and Image Localization). A key feature of this in-house QA solution, and central to this study, is an aSi flat-panel detector which provides the user with the means to perform accurate, immediate, and quantitative field analysis. Methods: The FOIL detector is automatically aligned in the CK beam using fiducial markers implanted within the detector case.more » Once the system is aligned, a treatment plan is delivered which irradiates the flat-panel imager using the field being tested. The current study tests each of the clinically-used fields shaped using the Iris variable-aperture collimation system using a plan which takes 6 minutes to deliver. The user is immediately provided with field diameter and beam profile, as well as a comparison to baseline values. Additionally, the detector is used to acquire and analyze leaf positions of the InCise multi-leaf collimation system. Results: Using a 6-minute plan consisting of 11 beams of 25MU-per-beam, the FOIL detector provided the user with a quantitative analysis of all clinically-used field shapes. The FOIL detector was also able to clearly resolve field edge junctions in a picket fence test, including slight over-travel of individual leaves as well as inter-leaf leakage. Conclusion: The FOIL system provided comparable field diameter and profile data when compared to methods using film; providing results much faster and with 5% of the MU used for film. When used with the MLC system, the FOIL detector provided the means for immediate quantification of the performance of the system through analysis of leaf positions in a picket fence test field. Author is the President/Owner of Spectrum Medical Physics, LLC, a company which maintains contracts with Siemens Healthcare and Standard Imaging, Inc.« less

Three dimensional equilibrium solutions for a current-carrying reversed-field pinch plasma with a close-fitting conducting shell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koliner, J. J.; Boguski, J., E-mail: boguski@wisc.edu; Anderson, J. K.

2016-03-15

In order to characterize the Madison Symmetric Torus (MST) reversed-field pinch (RFP) plasmas that bifurcate to a helical equilibrium, the V3FIT equilibrium reconstruction code was modified to include a conducting boundary. RFP plasmas become helical at a high plasma current, which induces large eddy currents in MST's thick aluminum shell. The V3FIT conducting boundary accounts for the contribution from these eddy currents to external magnetic diagnostic coil signals. This implementation of V3FIT was benchmarked against MSTFit, a 2D Grad-Shafranov solver, for axisymmetric plasmas. The two codes both fit B{sub θ} measurement loops around the plasma minor diameter with qualitative agreementmore » between each other and the measured field. Fits in the 3D case converge well, with q-profile and plasma shape agreement between two distinct toroidal locking phases. Greater than 60% of the measured n = 5 component of B{sub θ} at r = a is due to eddy currents in the shell, as calculated by the conducting boundary model.« less

Three dimensional equilibrium solutions for a current-carrying reversed-field pinch plasma with a close-fitting conducting shell

DOE PAGES

Koliner, J. J.; Boguski, J.; Anderson, J. K.; ...

2016-03-25

In order to characterize the Madison Symmetric Torus (MST) reversed-field pinch(RFP)plasmas that bifurcate to a helical equilibrium, the V3FIT equilibrium reconstruction code was modified to include a conducting boundary. RFPplasmas become helical at a high plasma current, which induces large eddy currents in MST's thick aluminum shell. The V3FIT conducting boundary accounts for the contribution from these eddy currents to external magnetic diagnostic coil signals. This implementation of V3FIT was benchmarked against MSTFit, a 2D Grad-Shafranov solver, for axisymmetric plasmas. The two codes both fit B measurement loops around the plasma minor diameter with qualitative agreement between each other andmore » the measured field. Fits in the 3D case converge well, with q-profile and plasma shape agreement between two distinct toroidal locking phases. Greater than 60% of the measured n = 5 component of B at r = a is due to eddy currents in the shell, as calculated by the conducting boundary model.« less

Improving the automated optimization of profile extrusion dies by applying appropriate optimization areas and strategies

NASA Astrophysics Data System (ADS)

Hopmann, Ch.; Windeck, C.; Kurth, K.; Behr, M.; Siegbert, R.; Elgeti, S.

2014-05-01

The rheological design of profile extrusion dies is one of the most challenging tasks in die design. As no analytical solution is available, the quality and the development time for a new design highly depend on the empirical knowledge of the die manufacturer. Usually, prior to start production several time-consuming, iterative running-in trials need to be performed to check the profile accuracy and the die geometry is reworked. An alternative are numerical flow simulations. These simulations enable to calculate the melt flow through a die so that the quality of the flow distribution can be analyzed. The objective of a current research project is to improve the automated optimization of profile extrusion dies. Special emphasis is put on choosing a convenient starting geometry and parameterization, which enable for possible deformations. In this work, three commonly used design features are examined with regard to their influence on the optimization results. Based on the results, a strategy is derived to select the most relevant areas of the flow channels for the optimization. For these characteristic areas recommendations are given concerning an efficient parameterization setup that still enables adequate deformations of the flow channel geometry. Exemplarily, this approach is applied to a L-shaped profile with different wall thicknesses. The die is optimized automatically and simulation results are qualitatively compared with experimental results. Furthermore, the strategy is applied to a complex extrusion die of a floor skirting profile to prove the universal adaptability.

SHAPEMOL: Modelling molecular line emission in protoplanetary and planetary nebulae with SHAPE

NASA Astrophysics Data System (ADS)

Santander-García, M.; Bujarrabal, V.; Steffen, W.; Koning, N.

2014-04-01

Modern instrumentation in radioastronomy constitutes a valuable tool for studying the Universe: ALMA will reach unprecedented sensitivities and spatial resolution, while Herschel/HIFI has opened a new window for probing molecular warm gas (˜50-1000 K). On the other hand, the SHAPE software has emerged in the last few years as the standard tool for determining the morphology and velocity field of different kinds of gaseous emission nebulae via spatio-kinematical modelling. Standard SHAPE implements radiative transfer solving, but it is only available for atomic species and not for molecules. Being aware of the growing importance of the development of tools for easying the analyses of molecular data from new era observatories, we introduce the computer code shapemol, a plug-in for SHAPE v5.0 with which we intend to fill the so far empty molecular niche. Shapemol enables spatio-kinematic modeling with accurate non-LTE calculations of line excitation and radiative transfer in molecular species. This code has been succesfully tested in the study of the excitation conditions of the molecular envelope of the young planetary nebula NGC 7027 using data from Herschel/HIFI and IRAM 30m. Currently, it allows radiative transfer solving in the 12CO and 13CO J=1-0 to J=17-16 lines. Shapemol, used along SHAPE, allows to easily generate synthetic maps to test against interferometric observations, as well as synthetic line profiles to match single-dish observations.

Lightning Nitrogen Oxides (LNOx) Vertical Profile Quantification and 10 Year Trend Analysis using Ozone Monitoring Instrument (OMI) Satellite Measurements, Air Quality Station (AQS) Surface Measurements, The National Lightning Detection Network (NLDN), and Simulated by Cloud Resolving Chemical Transport Model (REAM Cloud)

NASA Astrophysics Data System (ADS)

Smeltzer, C. D.; Wang, Y.; Koshak, W. J.

2014-12-01

Vertical profiles and emission lifetimes of lightning nitrogen oxides (LNOx) are derived using the Ozone Monitoring Instrument (OMI). Approximately 200 million flashes, over a 10 year climate period, from the United States National Lighting Detection Network (NLDN), are aggregated with OMI cloud top height to determine the vertical LNOx structure. LNOx lifetime is determined as function of LNOx signal in a 36 kilometer vertical column from the time of the last known flash to depletion of the LNOx signal. Environmental Protection Agency (EPA) Air Quality Station (AQS) surface data further support these results by demonstrating as much as a 200% increase in surface level NO2 during strong thunderstorm events and a lag as long as 5 to 8 hours from the lightning event to the peak surface event, indicating a evolutional process. Analysis of cloud resolving chemical transport model (REAM Cloud) demonstrates that C-shaped LNOx profiles, which agree with OMI vertical profile observations, evolve due to micro-scale convective meteorology given inverted C-shaped LNOx emission profiles as determined from lightning radio telemetry. It is shown, both in simulations and in observations, that the extent to which the LNOx vertical distribution is C-shaped and the lifetime of LNOx is proportional to the shear-strength of the thunderstorm. Micro-scale convective meteorology is not adequately parameterized in global scale and regional scale chemical transport models (CTM). Therefore, these larger scale CTMs ought to use a C-shape emissions profile to best reproduce observations until convective parameterizations are updated. These findings are used to simulate decadal LNOx and lightning ozone climatology over the Continental United States (CONUS) from 2004-2014.

Theoretical Compton profile anisotropies in molecules and solids. IV. Parallel--perpendicular anisotropies in alkali fluoride molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matcha, R.L.; Pettitt, B.M.; Ramirez, B.I.

1979-07-15

Calculations of Compton profiles and parallel--perpendicular anisotropies in alkali fluorides are presented and analyzed in terms of molecular charge distributions and wave function character. It is found that the parallel profile associated with the valence pi orbital is the principal factor determining the relative shapes of the total profile anisotropies in the low momentum region.

Laboratory Study on the Effect of Tidal Stream Turbines on Hydrodynamics and Sediment Dynamics

NASA Astrophysics Data System (ADS)

Amoudry, L.; Ramirez-Mendoza, R.; Peter, T.; McLelland, S.; Simmons, S.; Parsons, D. R.; Vybulkova, L.

2016-02-01

Tidal stream turbines (TST) are one potential technology for harnessing tidal energy, and the measurement and characterisation of their wakes is important both for environmental and development reasons. Indeed, wake recovery length is an important parameter for appropriate design of arrays, and wakes may result in altered dynamics both in the water column and at the seabed. We will report on laboratory scale experiments over a mobile sediment bed, which aim to quantify the detailed wake structure and its impact on sediment transport dynamics. A 0.2 m diameter model turbine was installed in a large-scale flume (16 m long, 1.6 m wide, 0.6 m deep) at the University of Hull's Total Environment Simulator and a steady current was driven over an artificial sediment bed using recirculating pumps. A high-resolution pulse-coherent acoustic Doppler profiler (Nortek Aquadopp HR) was used to measure vertical profiles of the three-dimensional mean current at different locations downstream of the model turbine. A three-dimensional Acoustic Ripple Profiler was used to map the bed and its evolution during the experiments. Acoustic backscatter systems were also deployed in two-dimensional arrays both along the flume and across the flume. These measurements revealed that the presence of the model turbine resulted in an expected reduction of the mean current and in changes in the vertical shear profiles. The bed mapping highlighted a horseshoe-shaped scour near the model turbine, and sediment deposition in the far wake region. The model turbine significantly influenced the suspension patterns, and generated significant asymmetry in the process, which was also evident from the other measurements (flow and sediment bed). These results highlight the effects induced by TSTs on near-bed hydrodynamics, suspension dynamics, and geomorphology, which may all have to be considered prior to large-scale deployments of arrays of TSTs in shelf seas.

Dynamic Energy Loss Characteristics in the Native Aortic Valve

NASA Astrophysics Data System (ADS)

Hwai Yap, Choon; Dasi, Laksmi P.; Yoganathan, Ajit P.

2009-11-01

Aortic Valve (AV) stenosis if untreated leads to heart failure. From a mechanics standpoint, heart failure implies failure to generate sufficient mechanical power to overcome energy losses in the circulation. Thus energy efficiency-based measures are direct measures of AV disease severity, which unfortunately is not used in current clinical measures of stenosis severity. We present an analysis of the dynamic rate of energy dissipation through the AV from direct high temporal resolution measurements of flow and pressure drop across the AV in a pulsatile left heart setup. Porcine AV was used and measurements at various conditions were acquired: varying stroke volumes; heart rates; and stenosis levels. Energy dissipation waveform has a distinctive pattern of being skewed towards late systole, attributed to the explosive growth of flow instabilities from adverse pressure gradient. Increasing heart rate and stroke volume increases energy dissipation, but does not alter the normalized shape of the dissipation temporal profile. Stenosis increases energy dissipation and also alters the normalized shape of dissipation waveform with significantly more losses during late acceleration phase. Since stenosis produces a departure from the signature dissipation waveform shape, dynamic energy dissipation analysis can be extended into a clinical tool for AV evaluation.

Development and Testing of a Shape Memory Alloy-Driven Composite Morphing Radiator

NASA Astrophysics Data System (ADS)

Walgren, P.; Bertagne, C.; Wescott, M.; Benafan, O.; Erickson, L.; Whitcomb, J.; Hartl, D.

2018-03-01

Future crewed deep space missions will require thermal control systems that can accommodate larger fluctuations in temperature and heat rejection loads than current designs. To maintain the crew cabin at habitable temperatures throughout the entire mission profile, radiators will be required to exhibit turndown ratios (defined as the ratio between the maximum and minimum heat rejection rates) as high as 12:1. Potential solutions to increase radiator turndown ratios include designs that vary the heat rejection rate by changing shape, hence changing the rate of radiation to space. Shape memory alloys exhibit thermally driven phase transformations and thus can be used for both the control and actuation of such a morphing radiator with a single active structural component that transduces thermal energy into motion. This work focuses on designing a high-performance composite radiator panel and investigating the behavior of various SMA actuators in this application. Three designs were fabricated and subsequently tested in a relevant thermal vacuum environment; all three exhibited repeatable morphing behavior, and it is shown through validated computational analysis that the morphing radiator concept can achieve a turndown ratio of 27:1 with a number of simple configuration changes.

Object-oriented approach to the automatic segmentation of bones from pediatric hand radiographs

NASA Astrophysics Data System (ADS)

Shim, Hyeonjoon; Liu, Brent J.; Taira, Ricky K.; Hall, Theodore R.

1997-04-01

The purpose of this paper is to develop a robust and accurate method that automatically segments phalangeal and epiphyseal bones from digital pediatric hand radiographs exhibiting various stages of growth. The development of this system draws principles from object-oriented design, model- guided analysis, and feedback control. A system architecture called 'the object segmentation machine' was implemented incorporating these design philosophies. The system is aided by a knowledge base where all model contours and other information such as age, race, and sex, are stored. These models include object structure models, shape models, 1-D wrist profiles, and gray level histogram models. Shape analysis is performed first by using an arc-length orientation transform to break down a given contour into elementary segments and curves. Then an interpretation tree is used as an inference engine to map known model contour segments to data contour segments obtained from the transform. Spatial and anatomical relationships among contour segments work as constraints from shape model. These constraints aid in generating a list of candidate matches. The candidate match with the highest confidence is chosen to be the current intermediate result. Verification of intermediate results are perform by a feedback control loop.

Shape memory polymer sensors for tracking cumulative environmental exposure

NASA Astrophysics Data System (ADS)

Snyder, Ryan; Rauscher, Michael; Vining, Ben; Havens, Ernie; Havens, Teresa; McFerran, Jace

2010-04-01

Cornerstone Research Group Inc. (CRG) has developed environmental exposure tracking (EET) sensors using shape memory polymers (SMP) to monitor the degradation of perishable items, such as munitions, foods and beverages, or medicines, by measuring the cumulative exposure to temperature and moisture. SMPs are polymers whose qualities have been altered to give them dynamic shape "memory" properties. Under thermal or moisture stimuli, the SMP exhibits a radical change from a rigid thermoset to a highly flexible, elastomeric state. The dynamic response of the SMP can be tailored to match the degradation profile of the perishable item. SMP-based EET sensors require no digital memory or internal power supply and provide the capability of inexpensive, long-term life cycle monitoring of thermal and moisture exposure over time. This technology was developed through Phase I and Phase II SBIR efforts with the Navy. The emphasis of current research centers on transitioning SMP materials from the lab bench to a production environment. Here, CRG presents the commercialization progress of thermally-activated EET sensors, focusing on fabrication scale-up, process refinements, and quality control. In addition, progress on the development of vapor pressure-responsive SMP (VPR-SMP) will be discussed.

Characteristics of binge eating disorder in relation to diagnostic criteria

PubMed Central

Wilfley, Denise E; Citrome, Leslie; Herman, Barry K

2016-01-01

The objective of this review was to examine the evidentiary basis for binge eating disorder (BED) with reference to the Diagnostic and Statistical Manual of Mental Disorders – Fifth Edition (DSM-5) diagnostic criteria for BED. A PubMed search restricted to titles and abstracts of English-language reviews, meta-analyses, clinical trials, randomized controlled trials, journal articles, and letters using human participants was conducted on August 7, 2015, using keywords that included “binge eating disorder,” DSM-5, DSM-IV, guilt, shame, embarrassment, quantity, psychological, behavior, and “shape and weight concerns.” Of the 257 retrieved publications, 60 publications were considered relevant to discussions related to DSM-5 diagnostic criteria and were included in the current review, and 20 additional references were also included on the basis of the authors’ knowledge and/or on a review of the reference lists from relevant articles obtained through the literature search. Evidence supports the duration/frequency criterion for BED and the primary importance of loss of control and marked distress in identifying individuals with BED. Although overvaluation of shape/weight is not a diagnostic criterion, its relationship to the severity of BED psychopathology may identify a unique subset of individuals with BED. Additionally, individuals with BED often exhibit a clinical profile consisting of psychiatric (eg, mood, obsessive–compulsive, and impulsive disorders) and medical (eg, gastrointestinal symptoms, metabolic syndrome, and type 2 diabetes) comorbidities and behavioral profiles (eg, overconsumption of calories outside of a binge eating episode and emotional eating). Future revisions of the BED diagnostic criteria should consider the inclusion of BED subtypes, perhaps based on the overvaluation of shape/weight, and an evidence-based reassessment of severity criteria. PMID:27621631

Simple Parametric Model for Airfoil Shape Description

NASA Astrophysics Data System (ADS)

Ziemkiewicz, David

2017-12-01

We show a simple, analytic equation describing a class of two-dimensional shapes well suited for representation of aircraft airfoil profiles. Our goal was to create a description characterized by a small number of parameters with easily understandable meaning, providing a tool to alter the shape with optimization procedures as well as manual tweaks by the designer. The generated shapes are well suited for numerical analysis with 2D flow solving software such as XFOIL.

Field mappers for laser material processing

NASA Astrophysics Data System (ADS)

Blair, Paul; Currie, Matthew; Trela, Natalia; Baker, Howard J.; Murphy, Eoin; Walker, Duncan; McBride, Roy

2016-03-01

The native shape of the single-mode laser beam used for high power material processing applications is circular with a Gaussian intensity profile. Manufacturers are now demanding the ability to transform the intensity profile and shape to be compatible with a new generation of advanced processing applications that require much higher precision and control. We describe the design, fabrication and application of a dual-optic, beam-shaping system for single-mode laser sources, that transforms a Gaussian laser beam by remapping - hence field mapping - the intensity profile to create a wide variety of spot shapes including discs, donuts, XY separable and rotationally symmetric. The pair of optics transform the intensity distribution and subsequently flatten the phase of the beam, with spot sizes and depth of focus close to that of a diffraction limited beam. The field mapping approach to beam-shaping is a refractive solution that does not add speckle to the beam, making it ideal for use with single mode laser sources, moving beyond the limits of conventional field mapping in terms of spot size and achievable shapes. We describe a manufacturing process for refractive optics in fused silica that uses a freeform direct-write process that is especially suited for the fabrication of this type of freeform optic. The beam-shaper described above was manufactured in conventional UV-fused silica using this process. The fabrication process generates a smooth surface (<1nm RMS), leading to laser damage thresholds of greater than 100J/cm2, which is well matched to high power laser sources. Experimental verification of the dual-optic filed mapper is presented.

Laser beam shaping for studying thermally induced damage

NASA Astrophysics Data System (ADS)

Masina, Bathusile N.; Bodkin, Richard; Mwakikunga, Bonex; Forbes, Andrew

2011-10-01

This paper presents an implementation of a laser beam shaping system for both heating a diamond tool and measuring the resulting temperature optically. The influence the initial laser parameters have on the resultant temperature profiles is shown experimentally and theoretically. A CO2 laser beam was used as the source to raise the temperature of the diamond tool and the resultant temperature was measured by using the blackbody principle. We have successfully transformed a Gaussian beam profile into a flat-top beam profile by using a diffractive optical element as a phase element in conjunction with a Fourier transforming lens. In this paper, we have successfully demonstrated temperature profiles across the diamond tool surface using two laser beam profiles and two optical setups, thus allowing a study of temperature influences with and without thermal stress. The generation of such temperature profiles on the diamond tool in the laboratory is important in the study of changes that occur in diamond tools, particularly the reduced efficiency of such tools in applications where extreme heating due to friction is expected.

Meniscus on a shaped fibre: singularities and hodograph formulation.

PubMed

Alimov, Mars M; Kornev, Konstantin G

2014-08-08

Using the method of matched asymptotic expansions, the problem of the capillary rise of a meniscus on the complex-shaped fibres was reduced to a nonlinear problem of determination of a minimal surface. This surface has to satisfy a special boundary condition at infinity. The proposed formulation allows one to interpret the meniscus problem as a problem of flow of a fictitious non-Newtonian fluid through a porous medium. As an example, the shape of a meniscus on a fibre of an oval cross section was analysed employing Chaplygin's hodograph transformation. It was discovered that the contact line may form singularities even if the fibre has a smooth profile: this statement was illustrated with an oval fibre profile having infinite curvature at two endpoints.

Meniscus on a shaped fibre: singularities and hodograph formulation

PubMed Central

Alimov, Mars M.; Kornev, Konstantin G.

2014-01-01

Using the method of matched asymptotic expansions, the problem of the capillary rise of a meniscus on the complex-shaped fibres was reduced to a nonlinear problem of determination of a minimal surface. This surface has to satisfy a special boundary condition at infinity. The proposed formulation allows one to interpret the meniscus problem as a problem of flow of a fictitious non-Newtonian fluid through a porous medium. As an example, the shape of a meniscus on a fibre of an oval cross section was analysed employing Chaplygin's hodograph transformation. It was discovered that the contact line may form singularities even if the fibre has a smooth profile: this statement was illustrated with an oval fibre profile having infinite curvature at two endpoints. PMID:25104910

Life satisfaction and age: Dealing with underidentification in age-period-cohort models.

PubMed

de Ree, Joppe; Alessie, Rob

2011-07-01

Recent literature typically finds a U shaped relationship between life satisfaction and age. Age profiles, however, are not identified without forcing arbitrary restrictions on the cohort and/or time profiles. In this paper we report what can be identified about the relationship between life satisfaction and age without applying such restrictions. Also, we identify the restrictions needed to conclude that life satisfaction is U shaped in age. For the case of Germany, we find that the relationship between life satisfaction and age is indeed U shaped, but only under the untestable condition that the linear time trend is negative and that the linear trend across birth cohorts is practically flat. Copyright © 2011 Elsevier Ltd. All rights reserved.

Optical fiber designs for beam shaping

NASA Astrophysics Data System (ADS)

Farley, Kevin; Conroy, Michael; Wang, Chih-Hao; Abramczyk, Jaroslaw; Campbell, Stuart; Oulundsen, George; Tankala, Kanishka

2014-03-01

A large number of power delivery applications for optical fibers require beams with very specific output intensity profiles; in particular applications that require a focused high intensity beam typically image the near field (NF) intensity distribution at the exit surface of an optical fiber. In this work we discuss optical fiber designs that shape the output beam profile to more closely correspond to what is required in many real world industrial applications. Specifically we present results demonstrating the ability to transform Gaussian beams to shapes required for industrial applications and how that relates to system parameters such as beam product parameter (BPP) values. We report on the how different waveguide structures perform in the NF and show results on how to achieve flat-top with circular outputs.

Phenotypic Plasticity of Cuticular Hydrocarbon Profiles in Insects.

PubMed

Otte, Tobias; Hilker, Monika; Geiselhardt, Sven

2018-03-01

The insect integument is covered by cuticular hydrocarbons (CHCs) which provide protection against environmental stresses, but are also used for communication. Here we review current knowledge on environmental and insect-internal factors which shape phenotypic plasticity of solitary living insects, especially herbivorous ones. We address the dynamics of changes which may occur within minutes, but may also last weeks, depending on the species and conditions. Two different modes of changes are suggested, i.e. stepwise and gradual. A switch between two distinct environments (e.g. host plant switch by phytophagous insects) results in stepwise formation of two distinct adaptive phenotypes, while a gradual environmental change (e.g. temperature gradients) induces a gradual change of numerous adaptive CHC phenotypes. We further discuss the ecological and evolutionary consequences of phenotypic plasticity of insect CHC profiles by addressing the question at which conditions is CHC phenotypic plasticity beneficial. The high plasticity of CHC profiles might be a trade-off for insects using CHCs for communication. We discuss how insects cope with the challenge to produce and "understand" a highly plastic, environmentally dependent CHC pattern that conveys reliable and comprehensible information. Finally, we outline how phenotypic plasticity of CHC profiles may promote speciation in insects that rely on CHCs for mate recognition.

Multi-spacecraft observations and transport simulations of solar energetic particles for the May 17th 2012 event

NASA Astrophysics Data System (ADS)

Battarbee, M.; Guo, J.; Dalla, S.; Wimmer-Schweingruber, R.; Swalwell, B.; Lawrence, D. J.

2018-05-01

Context. The injection, propagation and arrival of solar energetic particles (SEPs) during eruptive solar events is an important and current research topic of heliospheric physics. During the largest solar events, particles may have energies up to a few GeVs and sometimes even trigger ground-level enhancements (GLEs) at Earth. These large SEP events are best investigated through multi-spacecraft observations. Aims: We aim to study the first GLE-event of solar cycle 24, from 17th May 2012, using data from multiple spacecraft (SOHO, GOES, MSL, STEREO-A, STEREO-B and MESSENGER). These spacecraft are located throughout the inner heliosphere, at heliocentric distances between 0.34 and 1.5 astronomical units (au), covering nearly the whole range of heliospheric longitudes. Methods: We present and investigate sub-GeV proton time profiles for the event at several energy channels, obtained via different instruments aboard the above spacecraft. We investigated issues caused by magnetic connectivity, and present results of three-dimensional SEP propagation simulations. We gathered virtual time profiles and perform qualitative and quantitative comparisons with observations, assessed longitudinal injection and transport effects as well as peak intensities. Results: We distinguish different time profile shapes for well-connected and weakly connected observers, and find our onset time analysis to agree with this distinction. At select observers, we identify an additional low-energy component of Energetic Storm Particles (ESPs). Using well-connected observers for normalisation, our simulations are able to accurately recreate both time profile shapes and peak intensities at multiple observer locations. Conclusions: This synergetic approach combining numerical modelling with multi-spacecraft observations is crucial for understanding the propagation of SEPs within the interplanetary magnetic field. Our novel analysis provides valuable proof of the ability to simulate SEP propagation throughout the inner heliosphere, at a wide range of longitudes. Accurate simulations of SEP transport allow for better constraints of injection regions at the Sun, and thus, better understanding of acceleration processes.

Structural imprints in vivo decode RNA regulatory mechanisms.

PubMed

Spitale, Robert C; Flynn, Ryan A; Zhang, Qiangfeng Cliff; Crisalli, Pete; Lee, Byron; Jung, Jong-Wha; Kuchelmeister, Hannes Y; Batista, Pedro J; Torre, Eduardo A; Kool, Eric T; Chang, Howard Y

2015-03-26

Visualizing the physical basis for molecular behaviour inside living cells is a great challenge for biology. RNAs are central to biological regulation, and the ability of RNA to adopt specific structures intimately controls every step of the gene expression program. However, our understanding of physiological RNA structures is limited; current in vivo RNA structure profiles include only two of the four nucleotides that make up RNA. Here we present a novel biochemical approach, in vivo click selective 2'-hydroxyl acylation and profiling experiment (icSHAPE), which enables the first global view, to our knowledge, of RNA secondary structures in living cells for all four bases. icSHAPE of the mouse embryonic stem cell transcriptome versus purified RNA folded in vitro shows that the structural dynamics of RNA in the cellular environment distinguish different classes of RNAs and regulatory elements. Structural signatures at translational start sites and ribosome pause sites are conserved from in vitro conditions, suggesting that these RNA elements are programmed by sequence. In contrast, focal structural rearrangements in vivo reveal precise interfaces of RNA with RNA-binding proteins or RNA-modification sites that are consistent with atomic-resolution structural data. Such dynamic structural footprints enable accurate prediction of RNA-protein interactions and N(6)-methyladenosine (m(6)A) modification genome wide. These results open the door for structural genomics of RNA in living cells and reveal key physiological structures controlling gene expression.

Saturated Widths of Magnetic Islands in Tokamak Discharges

NASA Astrophysics Data System (ADS)

Halpern, F.; Pankin, A. Y.

2005-10-01

The new ISLAND module described in reference [1] implements a quasi-linear model to compute the widths of multiple magnetic islands driven by saturated tearing modes in toroidal plasmas of arbitrary aspect ratio and cross sectional shape. The distortion of the island shape caused by the radial variation in the perturbation is computed in the new module. In transport simulations, the enhanced transport caused by the magnetic islands has the effect of flattening the pressure and current density profiles. This self consistent treatment of the magnetic islands alters the development of the plasma profiles. In addition, it is found that islands closer to the magnetic axis influence the evolution of islands further out in the plasma. In order to investigate such phenomena, the ISLAND module is used within the BALDUR predictive modeling code to compute the widths of multiple magnetic islands in tokamak discharges. The interaction between the islands and sawtooth crashes is examined in simulations of DIII-D and JET discharges. The module is used to compute saturated neoclassical tearing mode island widths for multiple modes in ITER. Preliminary results for island widths in ITER are consistent with those presented [2] by Hegna. [1] F.D. Halpern, G. Bateman, A.H. Kritz and A.Y. Pankin, ``The ISLAND Module for Computing Magnetic Island Widths in Tokamaks,'' submitted to J. Plasma Physics (2005). [2] C.C. Hegna, 2002 Fusion Snowmass Meeting.

Numerical calculations of non-inductive current driven by microwaves in JET

NASA Astrophysics Data System (ADS)

Kirov, K. K.; Baranov, Yu; Mailloux, J.; Nave, M. F. F.; Contributors, JET

2016-12-01

Recent studies at JET focus on analysis of the lower hybrid (LH) wave power absorption and current drive (CD) calculations by means of a new ray tracing (RT)/Fokker-Planck (FP) package. The RT code works in real 2D geometry accounting for the plasma boundary and the launcher shape. LH waves with different parallel refractive index, {{N}\\parallel} , spectra in poloidal direction can be launched thus simulating authentic antenna spectrum with rows fed by different combinations of klystrons. Various FP solvers were tested most advanced of which is a relativistic bounce averaged FP code. LH wave power deposition profiles from the new RT/FP code were compared to the experimental results from electron cyclotron emission (ECE) analysis of pulses at 3.4 T low and high density. This kind of direct comparison between power deposition profiles from experimental ECE data and numerical model were carried out for the first time for waves in the LH range of frequencies. The results were in a reasonable agreement with experimental data at lower density, line averaged values of {{n}\\text{e}}≈ 2.4× {{10}19} {{\\text{m}}-3} . At higher density, {{n}\\text{e}}≈ 3× {{10}19} {{\\text{m}}-3} , the code predicted larger on-axis LH power deposition, which is inconsistent with the experimental observations. Both calculations were unable to produce LH wave absorption at the plasma periphery, which contradicts to the analysis of the ECE data and possible sources of these discrepancies have been briefly discussed in the paper. The code was also used to calculate the LH power deposition and CD profiles for the low-density preheat phase of JET’s advanced tokamak (AT) scenario. It was found that as the density evolves from hollow to flat and then to a more peaked profile the LH power and driven current move inward i.e. towards the plasma axis. A total driven current of about 70 kA for 1 MW of launched LH power was predicted in these conditions.

X-RAY EMISSION LINE PROFILES FROM WIND CLUMP BOW SHOCKS IN MASSIVE STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ignace, R.; Waldron, W. L.; Cassinelli, J. P.

2012-05-01

The consequences of structured flows continue to be a pressing topic in relating spectral data to physical processes occurring in massive star winds. In a preceding paper, our group reported on hydrodynamic simulations of hypersonic flow past a rigid spherical clump to explore the structure of bow shocks that can form around wind clumps. Here we report on profiles of emission lines that arise from such bow shock morphologies. To compute emission line profiles, we adopt a two-component flow structure of wind and clumps using two 'beta' velocity laws. While individual bow shocks tend to generate double-horned emission line profiles,more » a group of bow shocks can lead to line profiles with a range of shapes with blueshifted peak emission that depends on the degree of X-ray photoabsorption by the interclump wind medium, the number of clump structures in the flow, and the radial distribution of the clumps. Using the two beta law prescription, the theoretical emission measure and temperature distribution throughout the wind can be derived. The emission measure tends to be power law, and the temperature distribution is broad in terms of wind velocity. Although restricted to the case of adiabatic cooling, our models highlight the influence of bow shock effects for hot plasma temperature and emission measure distributions in stellar winds and their impact on X-ray line profile shapes. Previous models have focused on geometrical considerations of the clumps and their distribution in the wind. Our results represent the first time that the temperature distribution of wind clump structures are explicitly and self-consistently accounted for in modeling X-ray line profile shapes for massive stars.« less

Investigation on Convergence – Divergence Nozzle Shape for Microscale Channel in Harvesting Kinetic Energy

NASA Astrophysics Data System (ADS)

Zakaria, M. S.; Zairi, S.; Misbah, M. N.; Saifizi, M.; Rakawi, Izzudin

2018-03-01

This paper presents performance evaluation of nozzle shapes on microscale channel by employing different types of NACA airfoils profile and conventional profile. The deploying nozzle used are NACA 0012, NACA 0021 and NACA 0024 airfoils while for conventional convergence-divergence nozzle diameter ratio (d2 / d1) in the range from 1/4 to 3/4 are applied. These nozzles are assembled on rectangular cross sectional microscale channel which has designated constant fluid flow velocity at the channel inlet. This study revealed reduction on diameter ratio increased dramatically fluid velocity but further reduction on diameter ratio exposed fluid flow to fluctuate which slightly slowing down the fluid velocity. Nevertheless, curved NACA profiles are favourable for convergence – divergence nozzle in microscale channel as it significantly improved flow characteristics by enhancing fluid velocity and resultant kinetic energy as compared to conventional profile.

First-passage dynamics of linear stochastic interface models: weak-noise theory and influence of boundary conditions

NASA Astrophysics Data System (ADS)

Gross, Markus

2018-03-01

We consider a one-dimensional fluctuating interfacial profile governed by the Edwards–Wilkinson or the stochastic Mullins-Herring equation for periodic, standard Dirichlet and Dirichlet no-flux boundary conditions. The minimum action path of an interfacial fluctuation conditioned to reach a given maximum height M at a finite (first-passage) time T is calculated within the weak-noise approximation. Dynamic and static scaling functions for the profile shape are obtained in the transient and the equilibrium regime, i.e. for first-passage times T smaller or larger than the characteristic relaxation time, respectively. In both regimes, the profile approaches the maximum height M with a universal algebraic time dependence characterized solely by the dynamic exponent of the model. It is shown that, in the equilibrium regime, the spatial shape of the profile depends sensitively on boundary conditions and conservation laws, but it is essentially independent of them in the transient regime.

Surface Profile and Stress Field Evaluation using Digital Gradient Sensing Method

DOE PAGES

Miao, C.; Sundaram, B. M.; Huang, L.; ...

2016-08-09

Shape and surface topography evaluation from measured orthogonal slope/gradient data is of considerable engineering significance since many full-field optical sensors and interferometers readily output accurate data of that kind. This has applications ranging from metrology of optical and electronic elements (lenses, silicon wafers, thin film coatings), surface profile estimation, wave front and shape reconstruction, to name a few. In this context, a new methodology for surface profile and stress field determination based on a recently introduced non-contact, full-field optical method called digital gradient sensing (DGS) capable of measuring small angular deflections of light rays coupled with a robust finite-difference-based least-squaresmore » integration (HFLI) scheme in the Southwell configuration is advanced here. The method is demonstrated by evaluating (a) surface profiles of mechanically warped silicon wafers and (b) stress gradients near growing cracks in planar phase objects.« less

Cold spraying of aluminum bronze on profiled submillimeter cermet structures formed by laser cladding

NASA Astrophysics Data System (ADS)

Ryashin, N. S.; Malikov, A. G.; Shikalov, V. S.; Gulyaev, I. P.; Kuchumov, B. M.; Klinkov, S. V.; Kosarev, V. F.; Orishich, A. M.

2017-10-01

The paper presents results of the cold spraying of aluminum bronze coatings on substrates profiled with WC/Ni tracks obtained by laser cladding. Reinforcing cermet frames shaped as grids with varied mesh sizes were clad on stainless steel substrates using a CO2 laser machine "Siberia" (ITAM SB RAS, Russia). As a result, surfaces/substrates with heterogeneous shape, composition, and mechanical properties were obtained. Aluminum bronze coatings were deposited from 5lF-NS powder (Oerlikon Metco, Switzerland) on those substrates using cold spraying equipment (ITAM SB RAS). Data of profiling, microstructure diagnostics, EDS analysis, and mechanical tests of obtained composites is reported. Surface relief of the sprayed coatings dependence on substrate structure has been demonstrated.

Experimental Profiling of a Non-truncated Focused Gaussian Beam and Fine-tuning of the Quadratic Phase in the Fresnel Gaussian Shape Invariant

DOE Office of Scientific and Technical Information (OSTI.GOV)

S., Juan Manuel Franco; Cywiak, Moises; Cywiak, David

2015-06-24

A homodyne profiler is used for recording the intensity distribution of focused non-truncated Gaussian beams. The spatial distributions are obtained at planes in the vicinity of the back-focal plane of a focusing lens placed at different distances from a He–Ne laser beam with a Gaussian intensity profile. Comparisons of the experimental data with those obtained from the analytical equations for an ideal focusing lens allow us to propose formulae to fine-tune the quadratic term in the Fresnel Gaussian shape invariant at each interface of the propagated field. Furthermore, we give analytical expressions to calculate adequately the propagation of the fieldmore » through an optical system.« less

An examination of flame shape related to convection heat transfer in deep-fuel beds

Treesearch

Kara M. Yedinak; Jack D. Cohen; Jason M. Forthofer; Mark A. Finney

2010-01-01

Fire spread through a fuel bed produces an observable curved combustion interface. This shape has been schematically represented largely without consideration for fire spread processes. The shape and dynamics of the flame profile within the fuel bed likely reflect the mechanisms of heat transfer necessary for the pre-heating and ignition of the fuel during fire spread....

Impact of initial pulse shape on the nonlinear spectral compression in optical fibre

NASA Astrophysics Data System (ADS)

Boscolo, Sonia; Chaussard, Frederic; Andresen, Esben; Rigneault, Hervé; Finot, Christophe

2018-02-01

We theoretically study the effects of the temporal intensity profile of the initial pulse on the nonlinear propagation spectral compression process arising from nonlinear propagation in an optical fibre. Various linearly chirped input pulse profiles are considered, and their dynamics is explained with the aid of time-frequency representations. While initially parabolic-shaped pulses show enhanced spectral compression compared to Gaussian pulses, no significant spectral narrowing occurs when initially super-Gaussian pulses are used. Triangular pulses lead to a spectral interference phenomenon similar to the Fresnel bi-prism experiment.

Electron Temperature Evolution During Local Helicity Injection on the Pegasus Toroidal Experiment

NASA Astrophysics Data System (ADS)

Schlossberg, D. J.; Barr, J. L.; Bodner, G. M.; Bongard, M. W.; Fonck, R. J.; Perry, J. M.; Reusch, J. A.; Rodriguez Sanchez, C.

2016-10-01

Understanding the electron temperature (Te) evolution during local helicity injection (LHI) is critical for scaling up this non-solenoidal startup technique to MA-class devices. The first comprehensive Te measurements during LHI reveal centrally-peaked profiles with Te > 100 eV for plasma current Ip > 120 kA, toroidal field 0.15 T, and electron density ne 1019 m-3. Te rises and is sustained from just after magnetic relaxation through the plasma decoupling from edge-localized injectors. Results are presented for two injector edge locations: outboard midplane and inboard divertor. Outboard midplane injection couples LHI with inductive drive from poloidal field ramps and radial compression during inward plasma growth. Comparisons of Te at different LHI-to-inductive drive ratios show some profile flattening for higher LHI drive fraction. The latter, constant-shape discharges were necessarily lower performance, with Ip 50 kA and reduced Te , max. Inboard divertor injection achieves higher Ip using minimal inductive drive and thus isolates effects of LHI drive on Te. Initial results in this configuration show Te rising rapidly at the injector location as the discharge grows, settling to a roughly flat profile 100 eV. Thus far, both scenarios provide relatively stable discharges with moderate ne and high-Te, suitable for coupling to auxiliary current drive. Detailed studies of confinement dynamics and discharge optimization are planned for the near future. Work supported by US DOE Grant DE-FG02-96ER54375.

The virialization density of peaks with general density profiles under spherical collapse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubin, Douglas; Loeb, Abraham, E-mail: dsrubin@physics.harvard.edu, E-mail: aloeb@cfa.harvard.edu

2013-12-01

We calculate the non-linear virialization density, Δ{sub c}, of halos under spherical collapse from peaks with an arbitrary initial and final density profile. This is in contrast to the standard calculation of Δ{sub c} which assumes top-hat profiles. Given our formalism, the non-linear halo density can be calculated once the shape of the initial peak's density profile and the shape of the virialized halo's profile are provided. We solve for Δ{sub c} for halos in an Einstein de-Sitter and a ΛCDM universe. As examples, we consider power-law initial profiles as well as spherically averaged peak profiles calculated from the statisticsmore » of a Gaussian random field. We find that, depending on the profiles used, Δ{sub c} is smaller by a factor of a few to as much as a factor of 10 as compared to the density given by the standard calculation ( ≈ 200). Using our results, we show that, for halo finding algorithms that identify halos through an over-density threshold, the halo mass function measured from cosmological simulations can be enhanced at all halo masses by a factor of a few. This difference could be important when using numerical simulations to assess the validity of analytic models of the halo mass function.« less

Fast automatic 3D liver segmentation based on a three-level AdaBoost-guided active shape model

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Baochun; Huang, Cheng; Zhou, Shoujun

Purpose: A robust, automatic, and rapid method for liver delineation is urgently needed for the diagnosis and treatment of liver disorders. Until now, the high variability in liver shape, local image artifacts, and the presence of tumors have complicated the development of automatic 3D liver segmentation. In this study, an automatic three-level AdaBoost-guided active shape model (ASM) is proposed for the segmentation of the liver based on enhanced computed tomography images in a robust and fast manner, with an emphasis on the detection of tumors. Methods: The AdaBoost voxel classifier and AdaBoost profile classifier were used to automatically guide three-levelmore » active shape modeling. In the first level of model initialization, fast automatic liver segmentation by an AdaBoost voxel classifier method is proposed. A shape model is then initialized by registration with the resulting rough segmentation. In the second level of active shape model fitting, a prior model based on the two-class AdaBoost profile classifier is proposed to identify the optimal surface. In the third level, a deformable simplex mesh with profile probability and curvature constraint as the external force is used to refine the shape fitting result. In total, three registration methods—3D similarity registration, probability atlas B-spline, and their proposed deformable closest point registration—are used to establish shape correspondence. Results: The proposed method was evaluated using three public challenge datasets: 3Dircadb1, SLIVER07, and Visceral Anatomy3. The results showed that our approach performs with promising efficiency, with an average of 35 s, and accuracy, with an average Dice similarity coefficient (DSC) of 0.94 ± 0.02, 0.96 ± 0.01, and 0.94 ± 0.02 for the 3Dircadb1, SLIVER07, and Anatomy3 training datasets, respectively. The DSC of the SLIVER07 testing and Anatomy3 unseen testing datasets were 0.964 and 0.933, respectively. Conclusions: The proposed automatic approach achieves robust, accurate, and fast liver segmentation for 3D CTce datasets. The AdaBoost voxel classifier can detect liver area quickly without errors and provides sufficient liver shape information for model initialization. The AdaBoost profile classifier achieves sufficient accuracy and greatly decreases segmentation time. These results show that the proposed segmentation method achieves a level of accuracy comparable to that of state-of-the-art automatic methods based on ASM.« less

Fast automatic 3D liver segmentation based on a three-level AdaBoost-guided active shape model.

PubMed

He, Baochun; Huang, Cheng; Sharp, Gregory; Zhou, Shoujun; Hu, Qingmao; Fang, Chihua; Fan, Yingfang; Jia, Fucang

2016-05-01

A robust, automatic, and rapid method for liver delineation is urgently needed for the diagnosis and treatment of liver disorders. Until now, the high variability in liver shape, local image artifacts, and the presence of tumors have complicated the development of automatic 3D liver segmentation. In this study, an automatic three-level AdaBoost-guided active shape model (ASM) is proposed for the segmentation of the liver based on enhanced computed tomography images in a robust and fast manner, with an emphasis on the detection of tumors. The AdaBoost voxel classifier and AdaBoost profile classifier were used to automatically guide three-level active shape modeling. In the first level of model initialization, fast automatic liver segmentation by an AdaBoost voxel classifier method is proposed. A shape model is then initialized by registration with the resulting rough segmentation. In the second level of active shape model fitting, a prior model based on the two-class AdaBoost profile classifier is proposed to identify the optimal surface. In the third level, a deformable simplex mesh with profile probability and curvature constraint as the external force is used to refine the shape fitting result. In total, three registration methods-3D similarity registration, probability atlas B-spline, and their proposed deformable closest point registration-are used to establish shape correspondence. The proposed method was evaluated using three public challenge datasets: 3Dircadb1, SLIVER07, and Visceral Anatomy3. The results showed that our approach performs with promising efficiency, with an average of 35 s, and accuracy, with an average Dice similarity coefficient (DSC) of 0.94 ± 0.02, 0.96 ± 0.01, and 0.94 ± 0.02 for the 3Dircadb1, SLIVER07, and Anatomy3 training datasets, respectively. The DSC of the SLIVER07 testing and Anatomy3 unseen testing datasets were 0.964 and 0.933, respectively. The proposed automatic approach achieves robust, accurate, and fast liver segmentation for 3D CTce datasets. The AdaBoost voxel classifier can detect liver area quickly without errors and provides sufficient liver shape information for model initialization. The AdaBoost profile classifier achieves sufficient accuracy and greatly decreases segmentation time. These results show that the proposed segmentation method achieves a level of accuracy comparable to that of state-of-the-art automatic methods based on ASM.

The structure of clusters of galaxies

NASA Astrophysics Data System (ADS)

Fox, David Charles

When infalling gas is accreted onto a cluster of galaxies, its kinetic energy is converted to thermal energy in a shock, heating the ions. Using a self-similar spherical model, we calculate the collisional heating of the electrons by the ions, and predict the electron and ion temperature profiles. While there are significant differences between the two, they occur at radii larger than currently observable, and too large to explain observed X-ray temperature declines in clusters. Numerical simulations by Navarro, Frenk, & White (1996) predict a universal dark matter density profile. We calculate the expected number of multiply-imaged background galaxies in the Hubble Deep Field due to foreground groups and clusters with this profile. Such groups are up to 1000 times less efficient at lensing than the standard singular isothermal spheres. However, with either profile, the expected number of galaxies lensed by groups in the Hubble Deep Field is at most one, consistent with the lack of clearly identified group lenses. X-ray and Sunyaev-Zel'dovich (SZ) effect observations can be combined to determine the distance to clusters of galaxies, provided the clusters are spherical. When applied to an aspherical cluster, this method gives an incorrect distance. We demonstrate a method for inferring the three-dimensional shape of a cluster and its correct distance from X-ray, SZ effect, and weak gravitational lensing observations, under the assumption of hydrostatic equilibrium. We apply this method to simple, analytic models of clusters, and to a numerically simulated cluster. Using artificial observations based on current X-ray and SZ effect instruments, we recover the true distance without detectable bias and with uncertainties of 4 percent.

Eliminating the influence of source spectrum of white light scanning interferometry through time-delay estimation algorithm

NASA Astrophysics Data System (ADS)

Zhou, Yunfei; Cai, Hongzhi; Zhong, Liyun; Qiu, Xiang; Tian, Jindong; Lu, Xiaoxu

2017-05-01

In white light scanning interferometry (WLSI), the accuracy of profile measurement achieved with the conventional zero optical path difference (ZOPD) position locating method is closely related with the shape of interference signal envelope (ISE), which is mainly decided by the spectral distribution of illumination source. For a broadband light with Gaussian spectral distribution, the corresponding shape of ISE reveals a symmetric distribution, so the accurate ZOPD position can be achieved easily. However, if the spectral distribution of source is irregular, the shape of ISE will become asymmetric or complex multi-peak distribution, WLSI cannot work well through using ZOPD position locating method. Aiming at this problem, we propose time-delay estimation (TDE) based WLSI method, in which the surface profile information is achieved by using the relative displacement of interference signal between different pixels instead of the conventional ZOPD position locating method. Due to all spectral information of interference signal (envelope and phase) are utilized, in addition to revealing the advantage of high accuracy, the proposed method can achieve profile measurement with high accuracy in the case that the shape of ISE is irregular while ZOPD position locating method cannot work. That is to say, the proposed method can effectively eliminate the influence of source spectrum.

Investigation of the effect of tablet surface area/volume on drug release from hydroxypropylmethylcellulose controlled-release matrix tablets.

PubMed

Reynolds, Thomas D; Mitchell, Shawn A; Balwinski, Karen M

2002-04-01

The purpose of this study was to investigate the influence of tablet surface area/volume (SA/Vol) on drug release from controlled-release matrix tablets containing hydroxypropylmethylcellulose (HPMC). Soluble drugs (promethazine HCl, diphenhydramine HCl, and propranolol HCl) were utilized in this study to give predominantly diffusion-controlled release. Drug release from HPMC matrix tablets with similar values of SA/Vol was comparable within the same tablet shape (i.e., flat-faced round tablets) and among different shapes (i.e., oval, round concave, flat-faced beveled-edge, and flat-faced round tablets). Tablets having the same surface area but different SA/Vol values did not result in similar drug release; tablets with larger SA/Vol values hadfaster release profiles. Utility of SA/Vol to affect drug release was demonstrated by changing drug doses, and altering tablet shape to adjust SA/Vol. When SA/Vol was held constant, similar release profiles were obtained with f2 metric values greater than 70. Thus, surface area/volume is one of the key variables in controlling drug release from HPMC matrix tablets. Proper use of this variable has practical application by formulators who may need to duplicate drug release profiles from tablets of different sizes and different shapes.

Shape design of internal cooling passages within a turbine blade

NASA Astrophysics Data System (ADS)

Nowak, Grzegorz; Nowak, Iwona

2012-04-01

The article concerns the optimization of the shape and location of non-circular passages cooling the blade of a gas turbine. To model the shape, four Bezier curves which form a closed profile of the passage were used. In order to match the shape of the passage to the blade profile, a technique was put forward to copy and scale the profile fragments into the component, and build the outline of the passage on the basis of them. For so-defined cooling passages, optimization calculations were carried out with a view to finding their optimal shape and location in terms of the assumed objectives. The task was solved as a multi-objective problem with the use of the Pareto method, for a cooling system composed of four and five passages. The tool employed for the optimization was the evolutionary algorithm. The article presents the impact of the population on the task convergence, and discusses the impact of different optimization objectives on the Pareto optimal solutions obtained. Due to the problem of different impacts of individual objectives on the position of the solution front which was noticed during the calculations, a two-step optimization procedure was introduced. Also, comparative optimization calculations for the scalar objective function were carried out and set up against the non-dominated solutions obtained in the Pareto approach. The optimization process resulted in a configuration of the cooling system that allows a significant reduction in the temperature of the blade and its thermal stress.

Deducing noninductive current profile from surface voltage evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Litwin, C.; Wukitch, S.; Hershkowitz, N.

Solving the resistive diffusion equation in the presence of a noninductive current source determines the time-evolution of the surface voltage. By inverting the problem the current drive profile can be determined from the surface voltage evolution. We show that under wide range of conditions the deduced profile is unique. If the conductivity profile is known, this method can be employed to infer the noninductive current profile, and, ipso facto, the profile of the total current. We discuss the application of this method to analyze the Alfven wave current drive experiments in Phaedrus-T.

Determination of the vinyl fluoride line intensities by TDL spectroscopy: the object oriented approach of Visual Line Shape Fitting Program to line profile analysis

NASA Astrophysics Data System (ADS)

Tasinato, Nicola; Pietropolli Charmet, Andrea; Stoppa, Paolo; Giorgianni, Santi

2010-03-01

In this work the self-broadening coefficients and the integrated line intensities for a number of ro-vibrational transitions of vinyl fluoride have been determined for the first time by means of TDL spectroscopy. The spectra recorded in the atmospheric window around 8.7 µm appear very crowded with a density of about 90 lines per cm-1. In order to fit these spectral features a new fitting software has been implemented. The program, which is designed for laser spectroscopy, can fit many lines simultaneously on the basis of different theoretical profiles (Doppler, Lorentz, Voigt, Galatry and Nelkin-Ghatak). Details of the object oriented implementation of the application are given. The reliability of the program is demonstrated by determining the line parameters of some ro-vibrational lines of sulphur dioxide in the ν1 band region around 9 µm. Then the software is used for the line profile analysis of vinyl fluoride. The experimental line shapes show deviations from the Voigt profile, which can be well modelled by using a Dicke narrowed line shape function. This leads to the determination of the self-narrowing coefficient within the framework of the strong collision model.

Shaping Cutter Original Profile for Fine-module Ratchet Teeth Cutting

NASA Astrophysics Data System (ADS)

Sharkov, O. V.; Koryagin, S. I.; Velikanov, N. L.

2018-03-01

The methods for determining geometric characteristics of a theoretical original profile of the cutter for cutting ratchet teeth with a module of 0.3–1.0 mm are considered in the article. Design models describing the shaping process of cutting edges of cutter teeth are developed. Systems of expressions for determining coordinates of the points of front and back edges of cutter teeth; the workpiece angles of rotation during the cutting process; the minimum cutter radius are received. The basic data when using the proposed technique are: radii of circumferences passing through cavities of cutter teeth and external cut teeth; the gradient angle and length of straight section of the front edge of a cut tooth; angles of rotation of the cutter and the workpiece at the moment of shaping.

Characterization of plasma parameters in shaped PBX-M discharges

NASA Astrophysics Data System (ADS)

England, A. C.; Bell, R. E.; Hirshman, S. P.; Kaita, R.; Kugel, H. W.; LeBlanc, B. L.; Lee, D. K.; Okabayashi, M.; Sun, Y.-C.; Takahashi, H.

1997-09-01

The Princeton Beta Experiment-Modification (PBX-M) was run both with elliptical and with bean-shaped plasmas during the 1992 and 1993 operating periods. Two deuterium-fed neutral beams were used for auxiliary heating, and during 1992 the average power was 0741-3335/39/9/008/img13. This will be referred to as the lower neutral-beam power (LNBP) period. As many as four deuterium-fed neutral beams were used during 1993, and the average power was 0741-3335/39/9/008/img14. This will be referred to as the medium neutral-beam power (MNBP) period. The neutron source strength, Sn, showed a scaling with injected power 0741-3335/39/9/008/img15, 0741-3335/39/9/008/img16 for both the LMBP and MNBP periods. A much wider range of shaping parameters was studied during the MNBP as compared with the LNBP period. A weak positive dependence on bean shaping was observed for the LNBP, and a stronger positive dependence on shaping was observed for MNBP, viz 0741-3335/39/9/008/img17. High values of Sn were obtained in bean-shaped plasmas for the highest values of 0741-3335/39/9/008/img18 at 0741-3335/39/9/008/img19 for the LNBP. For the MNBP the highest values of Sn and stored energy were obtained at 0741-3335/39/9/008/img19, and the highest values of 0741-3335/39/9/008/img18 were obtained at 0741-3335/39/9/008/img22. The achievement of high Sn is aided by high neutral-beam power, high toroidal field, strong shaping, high electron temperature, and broad profiles. The achievement of high 0741-3335/39/9/008/img18 is aided by low toroidal field, high density, less shaping, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img24. The achievement of high 0741-3335/39/9/008/img25 is aided by strong shaping, high density, broad profiles, and access to the H-mode, viz 0741-3335/39/9/008/img26. Some comparisons with the previous higher neutral-beam (HNBP) period in 1989 are also made.

The Effects of Different Electrode Types for Obtaining Surface Machining Shape on Shape Memory Alloy Using Electrochemical Machining

NASA Astrophysics Data System (ADS)

Choi, S. G.; Kim, S. H.; Choi, W. K.; Moon, G. C.; Lee, E. S.

2017-06-01

Shape memory alloy (SMA) is important material used for the medicine and aerospace industry due to its characteristics called the shape memory effect, which involves the recovery of deformed alloy to its original state through the application of temperature or stress. Consumers in modern society demand stability in parts. Electrochemical machining is one of the methods for obtained these stabilities in parts requirements. These parts of shape memory alloy require fine patterns in some applications. In order to machine a fine pattern, the electrochemical machining method is suitable. For precision electrochemical machining using different shape electrodes, the current density should be controlled precisely. And electrode shape is required for precise electrochemical machining. It is possible to obtain precise square holes on the SMA if the insulation layer controlled the unnecessary current between electrode and workpiece. If it is adjusting the unnecessary current to obtain the desired shape, it will be a great contribution to the medical industry and the aerospace industry. It is possible to process a desired shape to the shape memory alloy by micro controlling the unnecessary current. In case of the square electrode without insulation layer, it derives inexact square holes due to the unnecessary current. The results using the insulated electrode in only side show precise square holes. The removal rate improved in case of insulated electrode than others because insulation layer concentrate the applied current to the machining zone.

A preliminary study on ice shape tracing with a laser light sheet

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.; Vargas, Mario; Oldenburg, John R.

1993-01-01

Preliminary work towards the development of an automated method of measuring the shape of ice forming on an airfoil during wind tunnel tests has been completed. A thin sheet of light illuminated the front surfaces of rime, glaze, and mixed ice shapes and a solid-state camera recorded images of each. A maximum intensity algorithm extracted the profiles of the ice shapes and the results were compared to hand tracings. Very good general agreement was found in each case.

Development And Characterization Of A Liner-On-Target Injector For Staged Z-Pinch Experiments

NASA Astrophysics Data System (ADS)

Valenzuela, J. C.; Conti, F.; Krasheninnikov, I.; Narkis, J.; Beg, F.; Wessel, F. J.; Rahman, H. U.

2016-10-01

We present the design and optimization of a liner-on-target injector for Staged Z-pinch experiments. The injector is composed of an annular high atomic number (e.g. Ar, Kr) gas-puff and an on-axis plasma gun that delivers the ionized deuterium target. The liner nozzle injector has been carefully studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated 1 cm radius gas profile that satisfies the theoretical requirement for best performance on the 1 MA Zebra current driver. The CFD simulations produce density profiles as a function of the nozzle shape and gas. These profiles are initialized in the MHD MACH2 code to find the optimal liner density for a stable, uniform implosion. We use a simple Snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector. We have performed line-integrated density measurements using a CW He-Ne laser to characterize the liner gas and the plasma gun density as a function of time. The measurements are compared with models and calculations and benchmarked accordingly. Advanced Research Projects Agency - Energy, DE-AR0000569.

OFT-1 reference flight profile. Deorbit through landing

NASA Technical Reports Server (NTRS)

Heath, D.; Gonzales, L.; Montez, M.; Hiott, J. M.; Ruda, R.; Kyle, H.

1977-01-01

Changes made in the de-orbiting through landing reference flight profile because of increases in Orbiter weight during entry and in the circular orbital attitude prior to deorbit are discussed. The rationale for the shaping of each phase is also presented.

Full-Physics Inverse Learning Machine for Satellite Remote Sensing of Ozone Profile Shapes and Tropospheric Columns

NASA Astrophysics Data System (ADS)

Xu, J.; Heue, K.-P.; Coldewey-Egbers, M.; Romahn, F.; Doicu, A.; Loyola, D.

2018-04-01

Characterizing vertical distributions of ozone from nadir-viewing satellite measurements is known to be challenging, particularly the ozone information in the troposphere. A novel retrieval algorithm called Full-Physics Inverse Learning Machine (FP-ILM), has been developed at DLR in order to estimate ozone profile shapes based on machine learning techniques. In contrast to traditional inversion methods, the FP-ILM algorithm formulates the profile shape retrieval as a classification problem. Its implementation comprises a training phase to derive an inverse function from synthetic measurements, and an operational phase in which the inverse function is applied to real measurements. This paper extends the ability of the FP-ILM retrieval to derive tropospheric ozone columns from GOME- 2 measurements. Results of total and tropical tropospheric ozone columns are compared with the ones using the official GOME Data Processing (GDP) product and the convective-cloud-differential (CCD) method, respectively. Furthermore, the FP-ILM framework will be used for the near-real-time processing of the new European Sentinel sensors with their unprecedented spectral and spatial resolution and corresponding large increases in the amount of data.

Surface roughness measurements

NASA Technical Reports Server (NTRS)

Howard, Thomas G.

1994-01-01

The Optics Division is currently in the research phase of producing grazing-incidence mirrors to be used in x-ray detector applications. The traditional method of construction involves labor-intensive glass grinding. This also culminates in a relatively heavy mirror. For lower resolution applications, the mirrors may be of a replicated design which involves milling a mandrel as a negative of the final shape and electroplating the cylindrical mirror onto it. The mirror is then separated from the mandrel by cooling. The mandrel will shrink more than the 'shell' (mirror) allowing it to be pulled from the mandrel. Ulmer (2) describes this technique and its variations in more detail. To date, several mirrors have been tested at MSFC by the Optical Fabrication Branch by focusing x-ray energy onto a detector with limited success. Little is known about the surface roughness of the actual mirror. Hence, the attempt to gather data on these surfaces. The test involves profiling the surface of a sample, replicating the surface as described above, and then profiling the replicated surface.

Injector design for liner-on-target gas-puff experiments

NASA Astrophysics Data System (ADS)

Valenzuela, J. C.; Krasheninnikov, I.; Conti, F.; Wessel, F.; Fadeev, V.; Narkis, J.; Ross, M. P.; Rahman, H. U.; Ruskov, E.; Beg, F. N.

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ˜1 cm radius gas profile that satisfies the theoretical requirement for best performance on ˜1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Injector design for liner-on-target gas-puff experiments.

PubMed

Valenzuela, J C; Krasheninnikov, I; Conti, F; Wessel, F; Fadeev, V; Narkis, J; Ross, M P; Rahman, H U; Ruskov, E; Beg, F N

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ∼1 cm radius gas profile that satisfies the theoretical requirement for best performance on ∼1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Technique Using Axicons For Generating Flat Top Laser Beam Profiles

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.; Woodfin, G. L.; Stahl, D.; Carpenter, J. P.; Kyrala, G.

1983-11-01

In certain fusion experiments using CO2 lasers, like Helios, it is desired to produce a focal spot several times larger than the nominal focal spot, with a flat beam profile. The typical focal spot in Helios is roughly 70 μm and just defocussing the beam produces beam breakup, with several hot spots with roughly the original diameter, and a gaussian distribution. A number of schemes were tried to achieve a large spot with desired characteristics. These are described in the article. Axicons were found to produce spots with desired characteristics. Axicons are lenses or mirrors having a cone-shaped surface. The various schemes are described, as well as an. experiment in Helios which confirmed that axicons produced the spots with desirable characteristics. Helios is an 8-beam CO2 laser which produces 10 kJ at power in excess of 20 TW. It is currently being used for Laser Fusion studies at the Los Alamos National Laboratory.

Mathematical Model of Solidification During Electroslag Casting of Pilger Roll

NASA Astrophysics Data System (ADS)

Liu, Fubin; Li, Huabing; Jiang, Zhouhua; Dong, Yanwu; Chen, Xu; Geng, Xin; Zang, Ximin

A mathematical model for describing the interaction of multiple physical fields in slag bath and solidification process in ingot during pilger roll casting with variable cross-section which is produced by the electroslag casting (ESC) process was developed. The commercial software ANSYS was applied to calculate the electromagnetic field, magnetic driven fluid flow, buoyancy-driven flow and heat transfer. The transportation phenomenon in slag bath and solidification characteristic of ingots are analyzed for variable cross-section with variable input power under the conditions of 9Cr3NiMo steel and 70%CaF2 - 30%Al2O3 slag system. The calculated results show that characteristic of current density distribution, velocity patterns and temperature profiles in the slag bath and metal pool profiles in ingot have distinct difference at variable cross-sections due to difference of input power and cooling condition. The pool shape and the local solidification time (LST) during Pilger roll ESC process are analyzed.

Trenonacog alfa for prophylaxis, on-demand and perioperative management of hemophilia B.

PubMed

Brennan, Yvonne; Curnow, Jennifer; Favaloro, Emmanuel J

2018-01-01

Current treatment for hemophilia B involves replacing the missing coagulation factor IX (FIX) with either plasma-derived or recombinant (r) FIX. Trenonacog alfa is the third normal half-life rFIX that has been granted FDA approval. Area covered: In this review, the authors examine trenonacog alfa for the treatment of hemophilia B including prophylaxis, on-demand and perioperative hemostasis. They compare the PK profile to nonacog alfa and evaluate the drug's efficacy and safety from published studies. Expert opinion: Trenonacog alfa appears to be an effective and safe treatment option for patients with hemophilia B with a PK profile similar to that of nonacog alfa. Despite the advent of extended half-life rFIX and other novel therapeutic approaches, normal half-life rFIX products, including trenonacog alfa, are likely to continue to have a place in hemophilia B treatment for at least the immediate future while the new landscape takes shape, particularly in countries that cannot afford the newer treatments.

Application of Traditional and Nanostructure Materials for Medical Electron Beams Collimation: Numerical Simulation

NASA Astrophysics Data System (ADS)

Miloichikova, I. A.; Stuchebrov, S. G.; Zhaksybayeva, G. K.; Wagner, A. R.

2015-11-01

Nowadays, the commercial application of the electron accelerators grows in the industry, in the research investigations, in the medical diagnosis and treatment. In this regard, the electron beam profile modification in accordance with specific purposes is an actual task. In this paper the model of the TPU microtron extracted electron beam developed in the program “Computer Laboratory (PCLab)” is described. The internal beam divergence influence for the electron beam profile and depth dose distribution in the air is considered. The possibility of using the nanostructure materials for the electron beam formation was analyzed. The simulation data of the electron beam shape collimated by different materials (lead, corund- zirconia nanoceramic, gypsum) are shown. The collimator material influence for the electron beam profile and shape are analyzed.

Advances in the steady-state hybrid regime in DIII-D – a fully non-inductive, ELM-suppressed scenario for ITER

DOE PAGES

Petty, Craig C.; Nazikian, Raffi; Park, Jin Myung; ...

2017-07-19

Here, the hybrid regime with beta, collisionality, safety factor and plasma shape relevant to the ITER steady-state mission has been successfully integrated with ELM suppression by applying an odd parity n=3 resonant magnetic perturbation (RMP). Fully non-inductive hybrids in the DIII-D tokamak with high beta (β ≤ 2.8%) and high confinement (98y2 ≤ 1.4) in the ITER similar shape have achieved zero surface loop voltage for up to two current relaxation times using efficient central current drive from ECCD and NBCD. The n=3 RMP causes surprisingly little increase in thermal transport during ELM suppression. Poloidal magnetic flux pumping in hybridmore » plasmas maintains q above 1 without loss of current drive efficiency, except that experiments show that extremely peaked ECCD profiles can create sawteeth. During ECCD, Alfvén eigenmode (AE) activity is replaced by a more benign fishbone-like mode, reducing anomalous beam ion diffusion by a factor of 2. While the electron and ion thermal diffusivities substantially increase with higher ECCD power, the loss of confinement can be offset by the decreased fast ion transport resulting from AE suppression. Extrapolations from DIII-D along a dimensionless parameter scaling path as well as those using self-consistent theory-based modeling show that these ELM-suppressed, fully non-inductive hybrids can achieve the Q = 5 ITER steady-state mission.« less

Variation of velocity profile according to blood viscosity in a microfluidic channel

NASA Astrophysics Data System (ADS)

Yeom, Eunseop; Kang, Yang Jun; Lee, Sang-Joon

2014-11-01

The shear-thinning effect of blood flows is known to change blood viscosity. Since blood viscosity and motion of red blood cells (RBCs) are closely related, hemorheological variations have a strong influence on hemodynamic characteristics. Therefore, understanding on the relationship between the hemorheological and hemodynamic properties is importance for getting more detailed information on blood circulation in microvessels. In this study, the blood viscosity and velocity profiles in a microfluidic channel were systematically investigated. Rat blood was delivered in the microfluidic device which can measure blood viscosity by monitoring the flow-switching phenomenon. Velocity profiles of blood flows in the microchannel were measured by using a micro-particle image velocimetry (PIV) technique. Shape of velocity profiles measured at different flow rates was quantified by using a curve-fitting equation. It was observed that the shape of velocity profiles is highly correlated with blood viscosity. The study on the relation between blood viscosity and velocity profile would be helpful to understand the roles of hemorheological and hemodynamic properties in cardiovascular diseases. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP) (No. 2008-0061991).

Velocity Profile measurements in two-phase flow using multi-wave sensors

NASA Astrophysics Data System (ADS)

Biddinika, M. K.; Ito, D.; Takahashi, H.; Kikura, H.; Aritomi, M.

2009-02-01

Two-phase flow has been recognized as one of the most important phenomena in fluid dynamics. In addition, gas-liquid two-phase flow appears in various industrial fields such as chemical industries and power generations. In order to clarify the flow structure, some flow parameters have been measured by using many effective measurement techniques. The velocity profile as one of the important flow parameter, has been measured by using ultrasonic velocity profile (UVP) technique. This technique can measure velocity distributions along a measuring line, which is a beam formed by pulse ultrasounds. Furthermore, a multi-wave sensor can measure the velocity profiles of both gas and liquid phase using UVP method. In this study, two types of multi-wave sensors are used. A sensor has cylindrical shape, and another one has square shape. The piezoelectric elements of each sensor have basic frequencies of 8 MHz for liquid phase and 2 MHz for gas phase, separately. The velocity profiles of air-water bubbly flow in a vertical rectangular channel were measured by using these multi-wave sensors, and the validation of the measuring accuracy was performed by the comparison between the velocity profiles measured by two multi-wave sensors.

Impact of the Hall effect on high-energy-density plasma jets.

PubMed

Gourdain, P-A; Seyler, C E

2013-01-04

Using a 1-MA, 100 ns-rise-time pulsed power generator, radial foil configurations can produce strongly collimated plasma jets. The resulting jets have electron densities on the order of 10(20) cm(-3), temperatures above 50 eV and plasma velocities on the order of 100 km/s, giving Reynolds numbers of the order of 10(3), magnetic Reynolds and Péclet numbers on the order of 1. While Hall physics does not dominate jet dynamics due to the large particle density and flow inside, it strongly impacts flows in the jet periphery where plasma density is low. As a result, Hall physics affects indirectly the geometrical shape of the jet and its density profile. The comparison between experiments and numerical simulations demonstrates that the Hall term enhances the jet density when the plasma current flows away from the jet compared to the case where the plasma current flows towards it.

Crystalline silicon solar cells with high resistivity emitter

NASA Astrophysics Data System (ADS)

Panek, P.; Drabczyk, K.; Zięba, P.

2009-06-01

The paper presents a part of research targeted at the modification of crystalline silicon solar cell production using screen-printing technology. The proposed process is based on diffusion from POCl3 resulting in emitter with a sheet resistance on the level of 70 Ω/□ and then, shaped by high temperature passivation treatment. The study was focused on a shallow emitter of high resistivity and on its influence on output electrical parameters of a solar cell. Secondary ion mass spectrometry (SIMS) has been employed for appropriate distinguishing the total donor doped profile. The solar cell parameters were characterized by current-voltage characteristics and spectral response (SR) methods. Some aspects playing a role in suitable manufacturing process were discussed. The situation in a photovoltaic industry with emphasis on silicon supply and current prices of solar cells, modules and photovoltaic (PV) systems are described. The economic and quantitative estimation of the PV world market is shortly discussed.

Laboratory measurements of white dwarf photospheric spectral lines: Hβ

DOE PAGES

Falcon, Ross Edward; Rochau, Gregory A.; Bailey, James E.; ...

2015-06-18

We spectroscopically measure multiple hydrogen Balmer line profiles from laboratory plasmas to investigate the theoretical line profiles used in white dwarf (WD) atmosphere models. X-ray radiation produced at the Z Pulsed Power Facility at Sandia National Laboratories initiates plasma formation in a hydrogen-filled gas cell, replicating WD photospheric conditions. We also present time-resolved measurements of Hβ and fit this line using different theoretical line profiles to diagnose electron density, n e, and n = 2 level population, n 2. Aided by synthetic tests, we characterize the validity of our diagnostic method for this experimental platform. During a single experiment, wemore » infer a continuous range of electron densities increasing from n e ~ 4 to ~30 × 10 16 cm -3 throughout a 120-ns evolution of our plasma. Also, we observe n 2 to be initially elevated with respect to local thermodynamic equilibrium (LTE); it then equilibrates within ~55 ns to become consistent with LTE. This also supports our electron-temperature determination of T e ~ 1.3 eV (~15,000 K) after this time. At n e≲ 10 17 cm -3, we find that computer-simulation-based line-profile calculations provide better fits (lower reduced χ 2) than the line profiles currently used in the WD astronomy community. The inferred conditions, however, are in good quantitative agreement. Lastly, this work establishes an experimental foundation for the future investigation of relative shapes and strengths between different hydrogen Balmer lines.« less

Peak shapes of acids and bases under overloaded conditions in reversed-phase liquid chromatography, with weakly buffered mobile phases of various pH: A thermodynamic interpretation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritti, Fabrice; Guiochon, Georges A

2009-01-01

We measured overloaded band profiles for a series of nine compounds (phenol, caffeine, 3-phenyl 1-propanol, 2-phenylbutyric acid, amphetamine, aniline, benzylamine, p-toluidine, and procainamidium chloride) on columns packed with four different C{sub 18}-bonded packing materials: XTerra-C{sub 18}, Gemini-C{sub 18}, Luna-C{sub 18}(2), and Halo-C{sub 18}, using buffered methanol-water mobile phases. The {sub W}{sup S}pH of the mobile phase was increased from 2.6 to 11.3. The buffer concentration (either phosphate, acetate, or carbonate buffers) was set constant at values below the maximum concentration of the sample in the band. The influence of the surface chemistry of the packing material on the retention andmore » the shape of the peaks was investigated. Adsorbents having a hybrid inorganic/organic structure tend to give peaks exhibiting moderate or little tailing. The retention and the shape of the band profiles can easily be interpreted at {sub W}{sup S}pHs that are well above or well below the {sub W}{sup S}pK{sub a} of the compound studied. In contrast, the peak shapes in the intermediary pH range (i.e., close to the compound {sub W}{sup S}pK{sub a}) have rarely been studied. These shapes reveal the complexity of the competitive adsorption behavior of couples of acido-basic conjugated compounds at {sub W}{sup S}pHs that are close to their {sub W}{sup S}pK{sub a}. They also reveal the role of the buffer capacity on the resulting peak shape. With increasing {sub W}{sup S}pH, the overloaded profiles are first langmuirian (isotherm type I) at low {sub W}{sup S}pHs, they become S-shaped (isotherm type II), then anti-langmuirian (isotherm type III), S-shaped again at intermediate {sub W}{sup S}pHs, and finally return to a langmuirian shape at high {sub W}{sup S}pHs. A new general adsorption isotherm model that takes into account the dissociation equilibrium of conjugated acidic and basic species in the bulk mobile phase accounts for these transient band shapes. An excellent agreement was achieved between experimental profiles and those calculated with a two-sites adsorption isotherm model at all {sub W}{sup S}pHs. The neutral species adsorbs strongly on a first type of sites that have a high density while the ionic species adsorb preferentially on a second type of sites that have a very low density. The evolution of the peak shape when the {sub W}{sup S}pH changes from acidic to basic is well explained by the weak buffer capacity of the mobile phase used compared to the concentration of the eluted compounds.« less

Cometary pick-up ions observed near Giacobini-Zinner

NASA Technical Reports Server (NTRS)

Gloeckler, G.; Hovestadt, D.; Ipavich, F. M.; Scholer, M.; Klecker, B.

1986-01-01

The number and energy density of cometary water-group ions observed near Comet Giacobini-Zinner are derived using the rest-frame distribution functions. The data reveal that density profiles of inbound and outbound passes and their shape correlate with pick-up ion production model predictions. The lose rate and production rate of water-group cometary molecules calculated from predicted and measured density profiles are 2 x 10 to the -6th/sec and 2.6 x 10 to the 28th/sec respectively. The shapes of the distribution functions are examined to study the solar wind/cometary ions interaction process.

Cometary pick-up ions observed near Giacobini-Zinner

NASA Astrophysics Data System (ADS)

Gloeckler, G.; Hovestadt, D.; Ipavich, F. M.; Scholer, M.; Klecker, B.; Galvin, A. B.

1986-03-01

The number and energy density of cometary water-group ions observed near Comet Giacobini-Zinner are derived using the rest-frame distribution functions. The data reveal that density profiles of inbound and outbound passes and their shape correlate with pick-up ion production model predictions. The lose rate and production rate of water-group cometary molecules calculated from predicted and measured density profiles are 2 x 10 to the -6th/sec and 2.6 x 10 to the 28th/sec respectively. The shapes of the distribution functions are examined to study the solar wind/cometary ions interaction process.

Improved ATIR concentrator photovoltaic module

NASA Astrophysics Data System (ADS)

Adriani, Paul M.; Mao, Erwang

2013-09-01

Novel aggregated total internal reflection (ATIR) concentrator photovoltaic module design comprises 2-D shaped primary and secondary optics that effectively combine optical efficiency, low profile, convenient range of acceptance angles, reliability, and manufacturability. This novel optical design builds upon previous investigations by improving the shapes of primary and secondary optics to enable improved long-term reliability and manufacturability. This low profile, low concentration (5x to 10x) design fits well with one-axis trackers that are often used for flat plate crystalline silicon photovoltaic modules in large scale ground mount installations. Standard mounting points, materials, and procedures apply without changes from flat plate modules.

Slip accumulation and lateral propagation of active normal faults in Afar

NASA Astrophysics Data System (ADS)

Manighetti, I.; King, G. C. P.; Gaudemer, Y.; Scholz, C. H.; Doubre, C.

2001-01-01

We investigate fault growth in Afar, where normal fault systems are known to be currently growing fast and most are propagating to the northwest. Using digital elevation models, we have examined the cumulative slip distribution along 255 faults with lengths ranging from 0.3 to 60 km. Faults exhibiting the elliptical or "bell-shaped" slip profiles predicted by simple linear elastic fracture mechanics or elastic-plastic theories are rare. Most slip profiles are roughly linear for more than half of their length, with overall slopes always <0.035. For the dominant population of NW striking faults and fault systems longer than 2 km, the slip profiles are asymmetric, with slip being maximum near the eastern ends of the profiles where it drops abruptly to zero, whereas slip decreases roughly linearly and tapers in the direction of overall Aden rift propagation. At a more detailed level, most faults appear to be composed of distinct, shorter subfaults or segments, whose slip profiles, while different from one to the next, combine to produce the roughly linear overall slip decrease along the entire fault. On a larger scale, faults cluster into kinematically coupled systems, along which the slip on any scale individual fault or fault system complements that of its neighbors, so that the total slip of the whole system is roughly linearly related to its length, with an average slope again <0.035. We discuss the origin of these quasilinear, asymmetric profiles in terms of "initiation points" where slip starts, and "barriers" where fault propagation is arrested. In the absence of a barrier, slip apparently extends with a roughly linear profile, tapered in the direction of fault propagation.

The RSA survey of dwarf galaxies, 1: Optical photometry

NASA Technical Reports Server (NTRS)

Vader, J. Patricia; Chaboyer, Brian

1994-01-01

We present detailed surface photometry, based on broad B-band charge coupled device (CCD) images, of about 80 dwarf galaxies. Our sample represents approximately 10% of all dwarf galaxies identified in the vicinity of Revised Shapley-Ames (RSA) galaxies on high resolution blue photographic plates, referred to as the RSA survey of dwarf galaxies. We derive global properties and radial surface brightness profiles, and examine the morphologies. The radial surface brightness profiles of dwarf galaxies, whether early or late type, display the same varieties in shape and complexity as those of classical giant galaxies. Only a few are well described by a pure r(exp 1/4) law. Exponential profiles prevail. Features typical of giant disk galaxies, such as exponential profiles with a central depression, lenses, and even, in one case (IC 2041), a relatively prominent bulge are also found in dwarf galaxies. Our data suggest that the central region evolves from being bulge-like, with an r(exp 1/4) law profile, in bright galaxies to a lens-like structure in dwarf galaxies. We prove detailed surface photometry to be a helpful if not always sufficient tool in investigating the structure of dwarf galaxies. In many cases kinematic information is needed to complete the picture. We find the shapes of the surface brightness profiles to be loosely associated with morphological type. Our sample contains several new galaxies with properties intermediate between those of giant and dwarf ellipticals (but no M32-like objects). This shows that such intermediate galaxies exist so that at least a fraction of early-type dwarf ellipticals is structurally related to early-type giants instead of belonging to a totally unrelated, disjunct family. This supports an origin of early-type dwarf galaxies as originally more massive systems that acquired their current morphology as a result of substantial, presumable supernova-driven, mass loss. On the other hand, several early-type dwarfs in our sample are merger candidates. Merger events may lead to anisotropic velocity distributions in systems of any luminosity, including dwarfs. The RSA sample of dwarf galaxies is more likely to contain mergers because, in contrast to earlier dwarf galaxy surveys that have focused on clusters and rich groups of galaxies, the RSA dwarfs are typically located in low density environments. The occurrence of mergers among dwarf galaxies is of interest in connection with the rapid evolution of faint blue galaxy counts at redshift z less than 1 which suggests that dwarf galaxies were about five times more numerous in the recent past. Finally, our sample contains several examples of late-type dwarfs and 'transition' types that are potential precursors of nucleated early-type dwarfs. All the above processes--mass loss, mergers, astration--are likely to have contributed to the formation of the current population of diffuse early-type dwarfs. A few new redshifts of dwarf galaxies are reported in this paper.

Wide-band profile domain pulsar timing analysis

NASA Astrophysics Data System (ADS)

Lentati, L.; Kerr, M.; Dai, S.; Hobson, M. P.; Shannon, R. M.; Hobbs, G.; Bailes, M.; Bhat, N. D. Ramesh; Burke-Spolaor, S.; Coles, W.; Dempsey, J.; Lasky, P. D.; Levin, Y.; Manchester, R. N.; Osłowski, S.; Ravi, V.; Reardon, D. J.; Rosado, P. A.; Spiewak, R.; van Straten, W.; Toomey, L.; Wang, J.; Wen, L.; You, X.; Zhu, X.

2017-04-01

We extend profile domain pulsar timing to incorporate wide-band effects such as frequency-dependent profile evolution and broad-band shape variation in the pulse profile. We also incorporate models for temporal variations in both pulse width and in the separation in phase of the main pulse and interpulse. We perform the analysis with both nested sampling and Hamiltonian Monte Carlo methods. In the latter case, we introduce a new parametrization of the posterior that is extremely efficient in the low signal-to-noise regime and can be readily applied to a wide range of scientific problems. We apply this methodology to a series of simulations, and to between seven and nine years of observations for PSRs J1713+0747, J1744-1134 and J1909-3744 with frequency coverage that spans 700-3600 Mhz. We use a smooth model for profile evolution across the full frequency range, and compare smooth and piecewise models for the temporal variations in dispersion measure (DM). We find that the profile domain framework consistently results in improved timing precision compared to the standard analysis paradigm by as much as 40 per cent for timing parameters. Incorporating smoothness in the DM variations into the model further improves timing precision by as much as 30 per cent. For PSR J1713+0747, we also detect pulse shape variation uncorrelated between epochs, which we attribute to variation intrinsic to the pulsar at a level consistent with previously published analyses. Not accounting for this shape variation biases the measured arrival times at the level of ˜30 ns, the same order of magnitude as the expected shift due to gravitational waves in the pulsar timing band.

A high resolution hand-held focused beam profiler

NASA Astrophysics Data System (ADS)

Zapata-Farfan, J.; Garduño-Mejía, J.; Rosete-Aguilar, M.; Ascanio, G.; Román-Moreno, C. J.

2017-05-01

The shape of a beam is important in any laser application and depending on the final implementation, there exists a preferred one which is defined by the irradiance distribution.1 The energy distribution (or laser beam profile) is an important parameter in a focused beam, for instance, in laser cut industry, where the beam shape determines the quality of the cut. In terms of alignment and focusing, the energy distribution also plays an important role since the system must be configured in order to reduce the aberration effects and achieve the highest intensity. Nowadays a beam profiler is used in both industry and research laboratories with the aim to characterize laser beams used in free-space communications, focusing and welding, among other systems. The purpose of the profile analyzers is to know the main parameters of the beam, to control its characteristics as uniformity, shape and beam size as a guide to align the focusing system. In this work is presented a high resolution hand-held and compact design of a beam profiler capable to measure at the focal plane, with covered range from 400 nm to 1000 nm. The detection is reached with a CMOS sensor sized in 3673.6 μm x 2738.4 μm which acquire a snap shot of the previously attenuated focused beam to avoid the sensor damage, the result is an image of beam intensity distribution, which is digitally processed with a RaspberryTMmodule gathering significant parameters such as beam waist, centroid, uniformity and also some aberrations. The profiler resolution is 1.4 μm and was probed and validated in three different focusing systems. The spot sizes measurements were compared with the Foucault knife-edge test.

Ferroelectric Plasma Sources for Ion Beam Neutralization

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L. R.; Davidson, R. C.

2014-10-01

A 40 keV Ar+ beam with a dimensionless perveance of 4 ×10-4 is propagated through a Ferroelectric Plasma Source (FEPS) to determine the effects of charge neutralization on the transverse beam profile. Neutralization is established 5 μs after the FEPS is triggered, and lasts between 10 and 35 μs. When the beam is fully neutralized, the profile has a Gaussian shape with a half-angle divergence of 0.87°, which is attributed to ion optics. The effects of the resistance and capacitance in the pulser circuit on the FEPS discharge are studied. The electron current emitted by the FEPS is calculated from measurements of the forward and return currents in the circuit. Electron emission typically begins 0.5 μs after the driving pulse, lasting for tens of μs, which is similar to the duration of ion beam neutralization. The total emitted charge does not depend significantly on the resistance, but depends strongly on the storage capacitance. Lowering the capacitance from 141 nF to 47 nF results in a near-complete shut-off of charge emission, although the amplitude of the applied voltage pulse is as high as when high-density plasma is produced. Overall, the data suggest that ferroelectric effects are significant in the physics of the FEPS discharge.

Reversible wavefront shaping between Gaussian and Airy beams by mimicking gravitational field

NASA Astrophysics Data System (ADS)

Wang, Xiangyang; Liu, Hui; Sheng, Chong; Zhu, Shining

2018-02-01

In this paper, we experimentally demonstrate reversible wavefront shaping through mimicking gravitational field. A gradient-index micro-structured optical waveguide with special refractive index profile was constructed whose effective index satisfying a gravitational field profile. Inside the waveguide, an incident broad Gaussian beam is firstly transformed into an accelerating beam, and the generated accelerating beam is gradually changed back to a Gaussian beam afterwards. To validate our experiment, we performed full-wave continuum simulations that agree with the experimental results. Furthermore, a theoretical model was established to describe the evolution of the laser beam based on Landau’s method, showing that the accelerating beam behaves like the Airy beam in the small range in which the linear potential approaches zero. To our knowledge, such a reversible wavefront shaping technique has not been reported before.

Diode laser spectroscopy: precise spectral line shape measurements

NASA Astrophysics Data System (ADS)

Nadezhdinskii, A. I.

1996-07-01

When one speaks about modern trends in tunable diode laser spectroscopy (TDLS) one should mention that precise line shape measurements have become one of the most promising applications of diode lasers in high resolution molecular spectroscopy. Accuracy limitations of TDL spectrometers are considered in this paper, proving the ability to measure spectral line profile with precision better than 1%. A four parameter Voigt profile is used to fit the experimental spectrum, and the possibility of line shift measurements with an accuracy of 2 × 10 -5 cm -1 is shown. Test experiments demonstrate the error line intensity ratios to be less than 0.3% for the proposed approach. Differences between "soft" and "hard" models of line shape have been observed experimentally for the first time. Some observed resonance effects are considered with respect to collision adiabacity.

Optimal design of damping layers in SMA/GFRP laminated hybrid composites

NASA Astrophysics Data System (ADS)

Haghdoust, P.; Cinquemani, S.; Lo Conte, A.; Lecis, N.

2017-10-01

This work describes the optimization of the shape profiles for shape memory alloys (SMA) sheets in hybrid layered composite structures, i.e. slender beams or thinner plates, designed for the passive attenuation of flexural vibrations. The paper starts with the description of the material and architecture of the investigated hybrid layered composite. An analytical method, for evaluating the energy dissipation inside a vibrating cantilever beam is developed. The analytical solution is then followed by a shape profile optimization of the inserts, using a genetic algorithm to minimize the SMA material layer usage, while maintaining target level of structural damping. Delamination problem at SMA/glass fiber reinforced polymer interface is discussed. At the end, the proposed methodology has been applied to study the hybridization of a wind turbine layered structure blade with SMA material, in order to increase its passive damping.

Recent Sedimentary Processes Along the Western Continental Margin of the South Korea Plateau, East Sea of Korea

NASA Astrophysics Data System (ADS)

Cukur, D.; Um, I. K.; Bahk, J. J.; Chun, J. H.; Lee, G. S.; Soo, K. G.; Horozal, S.; Kim, S. P.

2017-12-01

The continental margins of the marginal seas is largely shaped by a complex interplay of sediment transport processes directed both downslope and along-slope. Factors influence the sediment transport from shelf to the deep basin include: (i) seabed morphology, (ii) climate, (iii) sea level changes, (iv) slope stability, (v) oceanographic regime, and (vi) sediment sources. In order to understand the recent sedimentary processes along the western margin of the South Korea Plateau in the East Sea, we collected multiple geophysical datasets including the subbottom profiler and multibeam echosounder as well as geological sampling. Twelve echo types have been defined and interpreted as deposits formed by shallow marine, hemipelagic sedimentation, bottom currents, combined- (mass-movement/hemipelagic and hemipelagic/turbidites) and mass-movement-processes. Hemipelagic sedimentation, which is reflected as undisturbed layered sediments, appears to have been the primary sedimentary process throughout the study area. Two major slope-parallel channels appear to have acted as major conduits for turbidity currents from shallower shelf into the deep basins. Bottom current deposits, which is expressed as undulating seafloor morphology, are prevalent in the southern mid-slope at water depths between 250 to 450 m. Mass-transport deposits, consisting of chaotic seismic facies, occur in the upper and lower parts of the continental slope. Piston cores confirm the presence of MTDs that are characterized by mud clasts of variable size and shape. Multibeam bathymetry data show that these MTDs chiefly initiate on lower-slopes (400-600 m) where the gradient is up to 3°. In addition, subbottom profiles suggest the presence of numerous faults in close vicinity of headwall scarps; some are extending to the seafloor suggesting their recent activity. Earthquakes associated with tectonic activity are considered as the main triggering mechanism for these MTDs. Overall, the acoustic facies distribution shows that the sedimentary processes change downslope and differ within each physiographic province. In particular, the role of geological inheritance (i.e., structural folds and faults) on the geomorphology and sediment facies on the lower slopes appears to be quite important.

Efficient calculation of general Voigt profiles

NASA Astrophysics Data System (ADS)

Cope, D.; Khoury, R.; Lovett, R. J.

1988-02-01

An accurate and efficient program is presented for the computation of OIL profiles, generalizations of the Voigt profile resulting from the one-interacting-level model of Ward et al. (1974). These profiles have speed dependent shift and width functions and have asymmetric shapes. The program contains an adjustable error control parameter and includes the Voigt profile as a special case, although the general nature of this program renders it slower than a specialized Voigt profile method. Results on accuracy and computation time are presented for a broad set of test parameters, and a comparison is made with previous work on the asymptotic behavior of general Voigt profiles.

The RIASEC Profile of Foreign Language Teachers

ERIC Educational Resources Information Center

Swanson, Peter B.

2008-01-01

Vocational choice appears to crystallize during adolescence and one's career aspirations begin to take shape later. Over 40 years ago Holland studied incoming freshman to match vocational aspirations to vocational preference profiles. Individuals seeking to become foreign language teachers were assigned a Social, Artistic, Enterprising vocational…

Effect of resistivity profile on current decay time of initial phase of current quench in neon-gas-puff inducing disruptions of JT-60U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawakami, S.; Ohno, N.; Shibata, Y.

2013-11-15

According to an early work [Y. Shibata et al., Nucl. Fusion 50, 025015 (2010)] on the behavior of the plasma current decay in the JT-60U disruptive discharges caused by the radiative collapse with a massive neon-gas-puff, the increase of the internal inductance mainly determined the current decay time of plasma current during the initial phase of current quench. To investigate what determines the increase of the internal inductance, we focus attention on the relationship between the electron temperature (or the resistivity) profile and the time evolution of the current density profile and carry out numerical calculations. As a result, wemore » find the reason of the increase of the internal inductance: The current density profile at the start of the current quench is broader than an expected current density profile in the steady state, which is determined by the temperature (or resistivity) profile. The current density profile evolves into peaked one and the internal inductance is increasing.« less

Ion beams extraction and measurements of plasma parameters on a multi-frequencies microwaves large bore ECRIS with permanent magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nozaki, Dai; Kiriyama, Ryutaro; Takenaka, Tomoya

2012-11-06

We have developed an all-permanent magnet large bore electron cyclotron resonance ion source (ECRIS) for broad ion beam processing. The cylindrically comb-shaped magnetic field configuration is adopted for efficient plasma production and good magnetic confinement. To compensate for disadvantages of fixed magnetic configuration, a traveling wave tube amplifier (TWTA) is used. In the comb-shaped ECRIS, it is difficult to achieve controlling ion beam profiles in the whole inside the chamber by using even single frequency-controllable TWTA (11-13GHz), because of large bore size with all-magnets. We have tried controlling profiles of plasma parameters and then those of extracted ion beams bymore » launching two largely different frequencies simultaneously, i.e., multi-frequencies microwaves. Here we report ion beam profiles and corresponding plasma parameters under various experimental conditions, dependence of ion beams against extraction voltages, and influence of different electrode positions on the electron density profile.« less

NMRDSP: an accurate prediction of protein shape strings from NMR chemical shifts and sequence data.

PubMed

Mao, Wusong; Cong, Peisheng; Wang, Zhiheng; Lu, Longjian; Zhu, Zhongliang; Li, Tonghua

2013-01-01

Shape string is structural sequence and is an extremely important structure representation of protein backbone conformations. Nuclear magnetic resonance chemical shifts give a strong correlation with the local protein structure, and are exploited to predict protein structures in conjunction with computational approaches. Here we demonstrate a novel approach, NMRDSP, which can accurately predict the protein shape string based on nuclear magnetic resonance chemical shifts and structural profiles obtained from sequence data. The NMRDSP uses six chemical shifts (HA, H, N, CA, CB and C) and eight elements of structure profiles as features, a non-redundant set (1,003 entries) as the training set, and a conditional random field as a classification algorithm. For an independent testing set (203 entries), we achieved an accuracy of 75.8% for S8 (the eight states accuracy) and 87.8% for S3 (the three states accuracy). This is higher than only using chemical shifts or sequence data, and confirms that the chemical shift and the structure profile are significant features for shape string prediction and their combination prominently improves the accuracy of the predictor. We have constructed the NMRDSP web server and believe it could be employed to provide a solid platform to predict other protein structures and functions. The NMRDSP web server is freely available at http://cal.tongji.edu.cn/NMRDSP/index.jsp.

Comparison between rotary and manual instrumentation in primary teeth.

PubMed

Crespo, S; Cortes, O; Garcia, C; Perez, L

2008-01-01

The aim of this study was to compare the efficiency in both, preparation time and root canal shape, when using the Nickel Titanium (Ni-Ti) rotary and K-Files hand instrumentation on root canal preparation of single rooted primary teeth. Sixty single rooted primary teeth were selected and divided into two equal groups: Group (I) 30 teeth instrumented with manual K-files and group (II) 30 teeth instrumented with Ni-Ti rotary files (ProFile 0.04). Instrumentation times were calculated and root canal impressions were taken with light bodied silicone in order to evaluate the shape. The data was analyzed with SPSS program using the t-test and the Chi-square test to compare their means. The preparation time with group (I) K-files was significantly higher than in group (II) rotary files (ProFile 0.04), with a p= .005. The ProFile system showed a significantly more favorable canal taper when compared to the K-files system (P= .002). The use of rotary files in primary teeth has several advantages when compared with manual K files: the efficiency in both, preparation time and root canal shape. 1. A decreased working time, that helps maintain patient cooperation by diminishing the potential for tiredness. 2. The shape of the root canal is more conical, favoring a higher quality of the root canal filling, and increasing clinical success.

Ground penetrating radar and terrestrial laser scanner surveys on deposits of dilute pyroclastic density current deposits: insights for dune bedform genesis

NASA Astrophysics Data System (ADS)

Rémi Dujardin, Jean; Amin Douillet, Guilhem; Abolghasem, Amir; Cordonnier, Benoit; Kueppers, Ulrich; Bano, Maksim; Dingwell, Donald B.

2014-05-01

Dune bedforms formed by dilute pyroclastic density currents (PDC) are often described or interpreted as antidunes and chute and pools. However, the interpretation remains essentially speculative and is not well understood. This is largely due to the seeming impossibility of in-situ measurements and experimental scaling, as well as the lack of recent, 3D exposures. Indeed, most dune bedform cross-stratifications from the dilute PDC record outcrop in 2D sections. The 2006 eruption of Tungurahua has produced well-developed bedforms that are well-exposed on the surface of the deposits with easy access. We performed a survey of these deposits combining ground penetrating radar (GPR) profiling with terrestrial laser scanning of the surface. The GPR survey was carried in dense arrays (from 10 to 25 cm spacing between profiles) over ca. 10 m long bedforms. GPR profiles were corrected for topography from photogrammetry data. An in-house software, RadLab (written in matlab), was used for common processing of individual profiles and 2D & 3D topographic migration. Each topography-corrected profile was then loaded into a seismic interpretation software, OpenDtect, for 3D visualization and interpretation. Most bedforms show high lateral stability that is independent of the cross-stratification pattern (that varies between stoss-aggrading bedsets, stoss-erosive bedsets and stoss-depositional lensoidal layers). Anecdotic bedforms have their profiles that evolve laterally (i.e. in a direction perpendicular to the flow direction). Cannibalization of two dune bedforms into a single one on one end of the profile can evolve into growth of a single bedform at the other lateral end. Also, lateral variation in the migration direction occurs, i.e. a single bedform can show upstream aggradation at one lateral end of the bedform, but show downstream migration at the other end. Some bedforms have great variations in their internal structure. Several episodes of growth and erosion can be identified and reflect the dual control of the basal boundary for the location of a bedform, but the fluids dynamics control on the sedimentation pattern. The TLS data could not be geo-referenced and different clouds could not be combined. However, individual clouds or group of clouds permit a numerical analysis of the bedforms. Local average-extrema point the location of crests and troughs. The curvature of the surface elevation (eigenvalue of the curvature matrix) emphasizes the organization of the bedforms. Though noisy, the 2D Fourier transform permit to see a slight trend in the spectrum of a field of bedforms. As a whole, the dataset from the Tungurahua eruption allows us to rule out the interpretation as antidune that has been made for similar deposits. The outer shape of the bedforms and their internal structures are, in particular, not coherent with antidunes, and the downstream-size evolution as well as the outer shapes are not in agreement with interpretation of flow reversal for the formation of stoss-aggrading dune bedforms.

Thermal deformation of cryogenically cooled silicon crystals under intense X-ray beams: measurement and finite-element predictions of the surface shape

PubMed Central

Zhang, Lin; Sánchez del Río, Manuel; Monaco, Giulio; Detlefs, Carsten; Roth, Thomas; Chumakov, Aleksandr I.; Glatzel, Pieter

2013-01-01

X-ray crystal monochromators exposed to white-beam X-rays in third-generation synchrotron light sources are subject to thermal deformations that must be minimized using an adequate cooling system. A new approach was used to measure the crystal shape profile and slope of several cryogenically cooled (liquid nitrogen) silicon monochromators as a function of beam power in situ and under heat load. The method utilizes multiple angular scans across the Bragg peak (rocking curve) at various vertical positions of a narrow-gap slit downstream from the monochromator. When increasing the beam power, the surface of the liquid-nitrogen-cooled silicon crystal deforms from a concave shape at low heat load to a convex shape at high heat load, passing through an approximately flat shape at intermediate heat load. Finite-element analysis is used to calculate the crystal thermal deformations. The simulated crystal profiles and slopes are in excellent agreement with experiments. The parameters used in simulations, such as material properties, absorbed power distribution on the crystal and cooling boundary conditions, are described in detail as they are fundamental for obtaining accurate results. PMID:23765298

Development of non-conventional instrument transformers (NCIT) using smart materials

NASA Astrophysics Data System (ADS)

Nikolić, Bojan; Khan, Sanowar; Gabdullin, Nikita

2016-11-01

In this paper is presented a novel approach for current measurement using smart materials, magnetic shape memory (MSM) alloys. Their shape change can be controlled by the application of magnetic field or mechanical stress. This gives the possibility to measure currents by correlating the magnetic field produced by the current, shape change in an MSM- based sensor and the voltage output of a Linear Variable Differential Transducer (LVDT) actuated by this shape change. In the first part of the paper is presented a review of existing current measurement sensors by comparing their properties and highlighting their advantages and disadvantages.

Object Recognition in Flight: How Do Bees Distinguish between 3D Shapes?

PubMed Central

Werner, Annette; Stürzl, Wolfgang; Zanker, Johannes

2016-01-01

Honeybees (Apis mellifera) discriminate multiple object features such as colour, pattern and 2D shape, but it remains unknown whether and how bees recover three-dimensional shape. Here we show that bees can recognize objects by their three-dimensional form, whereby they employ an active strategy to uncover the depth profiles. We trained individual, free flying honeybees to collect sugar water from small three-dimensional objects made of styrofoam (sphere, cylinder, cuboids) or folded paper (convex, concave, planar) and found that bees can easily discriminate between these stimuli. We also tested possible strategies employed by the bees to uncover the depth profiles. For the card stimuli, we excluded overall shape and pictorial features (shading, texture gradients) as cues for discrimination. Lacking sufficient stereo vision, bees are known to use speed gradients in optic flow to detect edges; could the bees apply this strategy also to recover the fine details of a surface depth profile? Analysing the bees’ flight tracks in front of the stimuli revealed specific combinations of flight maneuvers (lateral translations in combination with yaw rotations), which are particularly suitable to extract depth cues from motion parallax. We modelled the generated optic flow and found characteristic patterns of angular displacement corresponding to the depth profiles of our stimuli: optic flow patterns from pure translations successfully recovered depth relations from the magnitude of angular displacements, additional rotation provided robust depth information based on the direction of the displacements; thus, the bees flight maneuvers may reflect an optimized visuo-motor strategy to extract depth structure from motion signals. The robustness and simplicity of this strategy offers an efficient solution for 3D-object-recognition without stereo vision, and could be employed by other flying insects, or mobile robots. PMID:26886006

Object Recognition in Flight: How Do Bees Distinguish between 3D Shapes?

PubMed

Werner, Annette; Stürzl, Wolfgang; Zanker, Johannes

2016-01-01

Honeybees (Apis mellifera) discriminate multiple object features such as colour, pattern and 2D shape, but it remains unknown whether and how bees recover three-dimensional shape. Here we show that bees can recognize objects by their three-dimensional form, whereby they employ an active strategy to uncover the depth profiles. We trained individual, free flying honeybees to collect sugar water from small three-dimensional objects made of styrofoam (sphere, cylinder, cuboids) or folded paper (convex, concave, planar) and found that bees can easily discriminate between these stimuli. We also tested possible strategies employed by the bees to uncover the depth profiles. For the card stimuli, we excluded overall shape and pictorial features (shading, texture gradients) as cues for discrimination. Lacking sufficient stereo vision, bees are known to use speed gradients in optic flow to detect edges; could the bees apply this strategy also to recover the fine details of a surface depth profile? Analysing the bees' flight tracks in front of the stimuli revealed specific combinations of flight maneuvers (lateral translations in combination with yaw rotations), which are particularly suitable to extract depth cues from motion parallax. We modelled the generated optic flow and found characteristic patterns of angular displacement corresponding to the depth profiles of our stimuli: optic flow patterns from pure translations successfully recovered depth relations from the magnitude of angular displacements, additional rotation provided robust depth information based on the direction of the displacements; thus, the bees flight maneuvers may reflect an optimized visuo-motor strategy to extract depth structure from motion signals. The robustness and simplicity of this strategy offers an efficient solution for 3D-object-recognition without stereo vision, and could be employed by other flying insects, or mobile robots.

A Parametric Approach to Shape Field-Relevant Blast Wave Profiles in Compressed-Gas-Driven Shock Tube

PubMed Central

Sundaramurthy, Aravind; Chandra, Namas

2014-01-01

Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1–3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68–1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is compared with the profiles obtained from the shock tube. To conclude, our experimental results demonstrate that a compressed-gas shock tube when designed and operated carefully can replicate the blast time profiles of field explosions accurately. Such a faithful replication is an essential first step when studying the effects of blast induced neurotrauma using animal models. PMID:25520701

A simplified 137Cs transport model for estimating erosion rates in undisturbed soil.

PubMed

Zhang, Xinbao; Long, Yi; He, Xiubin; Fu, Jiexiong; Zhang, Yunqi

2008-08-01

(137)Cs is an artificial radionuclide with a half-life of 30.12 years which released into the environment as a result of atmospheric testing of thermo-nuclear weapons primarily during the period of 1950s-1970s with the maximum rate of (137)Cs fallout from atmosphere in 1963. (137)Cs fallout is strongly and rapidly adsorbed by fine particles in the surface horizons of the soil, when it falls down on the ground mostly with precipitation. Its subsequent redistribution is associated with movements of the soil or sediment particles. The (137)Cs nuclide tracing technique has been used for assessment of soil losses for both undisturbed and cultivated soils. For undisturbed soils, a simple profile-shape model was developed in 1990 to describe the (137)Cs depth distribution in profile, where the maximum (137)Cs occurs in the surface horizon and it exponentially decreases with depth. The model implied that the total (137)Cs fallout amount deposited on the earth surface in 1963 and the (137)Cs profile shape has not changed with time. The model has been widely used for assessment of soil losses on undisturbed land. However, temporal variations of (137)Cs depth distribution in undisturbed soils after its deposition on the ground due to downward transport processes are not considered in the previous simple profile-shape model. Thus, the soil losses are overestimated by the model. On the base of the erosion assessment model developed by Walling, D.E., He, Q. [1999. Improved models for estimating soil erosion rates from cesium-137 measurements. Journal of Environmental Quality 28, 611-622], we discuss the (137)Cs transport process in the eroded soil profile and make some simplification to the model, develop a method to estimate the soil erosion rate more expediently. To compare the soil erosion rates calculated by the simple profile-shape model and the simple transport model, the soil losses related to different (137)Cs loss proportions of the reference inventory at the Kaixian site of the Three Gorge Region, China are estimated by the two models. The over-estimation of the soil loss by using the previous simple profile-shape model obviously increases with the time period from the sampling year to the year of 1963 and (137)Cs loss proportion of the reference inventory. As to 20-80% of (137)Cs loss proportions of the reference inventory at the Kaixian site in 2004, the annual soil loss depths estimated by the new simplified transport process model are only 57.90-56.24% of the values estimated by the previous model.

The variation of rotation curve shapes as a signature of the effects of baryons on dark matter density profiles

NASA Astrophysics Data System (ADS)

Brook, Chris B.

2015-12-01

Rotation curves of galaxies show a wide range of shapes, which can be paramaterized as scatter in Vrot(1 kpc)/Vmax , i.e. the ratio of the rotation velocity measured at 1 kpc and the maximum measured rotation velocity. We examine whether the observed scatter can be accounted for by combining scatters in disc scalelengths, the concentration-halo mass relation, and the M⋆-Mhalo relation. We use these scatters to create model galaxy populations; when housed within dark matter haloes that have universal, Navarro, Frenk & White density profiles, the model does not match the lowest observed values of Vrot(1 kpc)/Vmax and has too little scatter in Vrot(1 kpc)/Vmax compared to observations. By contrast, a model using a mass-dependent dark matter profile, where the inner slope is determined by the ratio of M⋆/Mhalo, produces galaxies with low values of Vrot(1 kpc)/Vmax and a much larger scatter, both in agreement with observation. We conclude that the large observed scatter in Vrot(1 kpc)/Vmax favours density profiles that are significantly affected by baryonic processes. Alternative dark matter core formation models such as self-interacting dark matter may also account for the observed variation in rotation curve shapes, but these observations may provide important constraints in terms of core sizes, and whether they vary with halo mass and/or merger history.

The Effects of Low Dose-Rate Ionizing Radiation on the Shapes of Transients in the LM124 Operational Amplifier

NASA Technical Reports Server (NTRS)

Buchner, Stephen; McMorrow, Dale; Roche, Nicholas; Dusseau, Laurent; Pease, Ron L.

2008-01-01

Shapes of single event transients (SETs) in a linear bipolar circuit (LM124) change with exposure to total ionizing dose (TID) radiation. SETs shape changes are a direct consequence of TID-induced degradation of bipolar transistor gain. A reduction in transistor gain causes a reduction in the drive current of the current sources in the circuit, and it is the lower drive current that most affects the shapes of large amplitude SETs.

Effect of ring-shaped SiO2 current blocking layer thickness on the external quantum efficiency of high power light-emitting diodes

NASA Astrophysics Data System (ADS)

Zhou, Shengjun; Liu, Mengling; Hu, Hongpo; Gao, Yilin; Liu, Xingtong

2017-12-01

A ring-shaped SiO2 CBL underneath the p-electrode was employed to enhance current spreading of GaN-based light-emitting diodes (LEDs). Effects of ring-shaped SiO2 current blocking layer (CBL) thickness on optical and electrical characteristics of high power LEDs were investigated. A 190-nm-thick ring-shaped SiO2 CBL with inclined sidewalls was obtained using a combination of a thermally reflowed photoresist technique and an inductively coupled plasma (ICP) etching process, allowing for the deposition of conformal indium tin oxide (ITO) transparent conductive layer on sidewalls of ring-shaped SiO2 CBL. It was indicated that the external quantum efficiency (EQE) of high power LEDs increased with increasing thickness of ring-shaped SiO2 CBL. The EQE of high power LED with 190-nm-thick ring-shaped SiO2 CBL was 12.7% higher than that of high power LED without SiO2 CBL. Simulations performed with commercial SimuLED software package showed that the ring-shaped SiO2 CBL could significantly alleviate current crowding around p-electrode, resulting in enhanced current spreading over the entire high power LED structure.

Comparison of GOME tropospheric NO2 columns with NO2 profiles deduced from ground-based in situ measurements

NASA Astrophysics Data System (ADS)

Schaub, D.; Boersma, K. F.; Kaiser, J. W.; Weiss, A. K.; Folini, D.; Eskes, H. J.; Buchmann, B.

2006-08-01

Nitrogen dioxide (NO2) vertical tropospheric column densities (VTCs) retrieved from the Global Ozone Monitoring Experiment (GOME) are compared to coincident ground-based tropospheric NO2 columns. The ground-based columns are deduced from in situ measurements at different altitudes in the Alps for 1997 to June 2003, yielding a unique long-term comparison of GOME NO2 VTC data retrieved by a collaboration of KNMI (Royal Netherlands Meteorological Institute) and BIRA/IASB (Belgian Institute for Space Aeronomy) with independently derived tropospheric NO2 profiles. A first comparison relates the GOME retrieved tropospheric columns to the tropospheric columns obtained by integrating the ground-based NO2 measurements. For a second comparison, the tropospheric profiles constructed from the ground-based measurements are first multiplied with the averaging kernel (AK) of the GOME retrieval. The second approach makes the comparison independent from the a priori NO2 profile used in the GOME retrieval. This allows splitting the total difference between the column data sets into two contributions: one that is due to differences between the a priori and the ground-based NO2 profile shapes, and another that can be attributed to uncertainties in both the remaining retrieval parameters (such as, e.g., surface albedo or aerosol concentration) and the ground-based in situ NO2 profiles. For anticyclonic clear sky conditions the comparison indicates a good agreement between the columns (n=157, R=0.70/0.74 for the first/second comparison approach, respectively). The mean relative difference (with respect to the ground-based columns) is -7% with a standard deviation of 40% and GOME on average slightly underestimating the ground-based columns. Both data sets show a similar seasonal behaviour with a distinct maximum of spring NO2 VTCs. Further analysis indicates small GOME columns being systematically smaller than the ground-based ones. The influence of different shapes in the a priori and the ground-based NO2 profile is analysed by considering AK information. It is moderate and indicates similar shapes of the profiles for clear sky conditions. Only for large GOME columns, differences between the profile shapes explain the larger part of the relative difference. In contrast, the other error sources give rise to the larger relative differences found towards smaller columns. Further, for the clear sky cases, errors from different sources are found to compensate each other partially. The comparison for cloudy cases indicates a poorer agreement between the columns (n=60, R=0.61). The mean relative difference between the columns is 60% with a standard deviation of 118% and GOME on average overestimating the ground-based columns. The clear improvement after inclusion of AK information (n=60, R=0.87) suggests larger errors in the a priori NO2 profiles under cloudy conditions and demonstrates the importance of using accurate profile information for (partially) clouded scenes.

HBT-EP Program: MHD Dynamics and Active Control through 3D Fields and Currents

NASA Astrophysics Data System (ADS)

Navratil, G. A.; Bialek, J.; Brooks, J. W.; Byrne, P. J.; Desanto, S.; Levesque, J. P.; Mauel, M. E.; Stewart, I. G.; Hansen, C. J.

2017-10-01

The HBT-EP active mode control research program aims to: (i) advance understanding of the effects of 3D shaping on advanced tokamak fusion performance, (ii) resolve important MHD issues associated with disruptions, and (iii) measure and mitigate the effects of 3D scrape-off layer (SOL) currents through active and passive control of the plasma edge and conducting boundary structures. Comparison of kink mode structure and RMP response in circular versus diverted plasmas shows good agreement with DCON modeling. SOL current measurements have been used to study SOL current dynamics and current-sharing with the vacuum vessel wall during kink-mode growth and disruptions. A multi-chord extreme UV/soft X-ray array is being installed to provide detailed internal mode structure information. Internal local electrodes were used to apply local bias voltage at two radial locations to study the effect of rotation profile on MHD mode rotation and stability and radial current flow through the SOL. A GPU-based low latency control system using 96 inputs and 64 outputs to apply magnetic perturbations for active control of kink modes is extended to directly control the SOL currents for kink-mode control. An extensive array of SOL current monitors and edge drive electrodes are being installed for pioneering studies of helical edge current control. Supported by U.S. DOE Grant DE-FG02-86ER53222.

Spatially modulated laser pulses for printing electronics.

PubMed

Auyeung, Raymond C Y; Kim, Heungsoo; Mathews, Scott; Piqué, Alberto

2015-11-01

The use of a digital micromirror device (DMD) in laser-induced forward transfer (LIFT) is reviewed. Combining this technique with high-viscosity donor ink (silver nanopaste) results in laser-printed features that are highly congruent in shape and size to the incident laser beam spatial profile. The DMD empowers LIFT to become a highly parallel, rapidly reconfigurable direct-write technology. By adapting half-toning techniques to the DMD bitmap image, the laser transfer threshold fluence for 10 μm features can be reduced using an edge-enhanced beam profile. The integration of LIFT with this beam-shaping technique allows the printing of complex large-area patterns with a single laser pulse.

Shape and Composition Map of a Prepyramid Quantum Dot

NASA Astrophysics Data System (ADS)

Spencer, Brian

2006-03-01

We present a theory for the shape, size, and nonuniform composition profile of a small prepyramid island in an alloy epitaxial film when surface diffusion is much faster than deposition and bulk diffusion. The predicted composition profile has segregation of the larger misfit component to the island peak, with segregation enhanced by misfit strain and solute strain but retarded by alloy solution thermodynamics. Vertical composition gradients through the center of the island due to this mechanism are on the order of 2%/nm for GeXSi1-X/Si and 10 - 15%/nm for InXGaAs1-X/GaAs [PRL 95, 206101 (2005)].

The ratio of profile peak separations as a probe of pulsar radio-beam structure

NASA Astrophysics Data System (ADS)

Dyks, J.; Pierbattista, M.

2015-12-01

The known population of pulsars contains objects with four- and five-component profiles, for which the peak-to-peak separations between the inner and outer components can be measured. These Q- and M-type profiles can be interpreted as a result of sightline cut through a nested-cone beam, or through a set of azimuthal fan beams. We show that the ratio RW of the components' separations provides a useful measure of the beam shape, which is mostly independent of parameters that determine the beam scale and complicate interpretation of simpler profiles. In particular, the method does not depend on the emission altitude and the dipole tilt distribution. The different structures of the radio beam imply manifestly different statistical distributions of RW, with the conal model being several orders of magnitude less consistent with data than the fan-beam model. To bring the conal model into consistency with data, strong effects of observational selection need to be called for, with 80 per cent of Q and M profiles assumed to be undetected because of intrinsic blending effects. It is concluded that the statistical properties of Q and M profiles are more consistent with the fan-shaped beams, than with the traditional nested-cone geometry.

The impact of baryonic discs on the shapes and profiles of self-interacting dark matter halos

NASA Astrophysics Data System (ADS)

Sameie, Omid; Creasey, Peter; Yu, Hai-Bo; Sales, Laura V.; Vogelsberger, Mark; Zavala, Jesús

2018-06-01

We employ isolated N-body simulations to study the response of self-interacting dark matter (SIDM) halos in the presence of the baryonic potentials. Dark matter self-interactions lead to kinematic thermalization in the inner halo, resulting in a tight correlation between the dark matter and baryon distributions. A deep baryonic potential shortens the phase of SIDM core expansion and triggers core contraction. This effect can be further enhanced by a large self-scattering cross section. We find the final SIDM density profile is sensitive to the baryonic concentration and the strength of dark matter self-interactions. Assuming a spherical initial halo, we also study evolution of the SIDM halo shape together with the density profile. The halo shape at later epochs deviates from spherical symmetry due to the influence of the non-spherical disc potential, and its significance depends on the baryonic contribution to the total gravitational potential, relative to the dark matter one. In addition, we construct a multi-component model for the Milky Way, including an SIDM halo, a stellar disc and a bulge, and show it is consistent with observations from stellar kinematics and streams.

Patterns and Prevalence of Core Profile Types in the WPPSI Standardization Sample.

ERIC Educational Resources Information Center

Glutting, Joseph J.; McDermott, Paul A.

1990-01-01

Found most representative subtest profiles for 1,200 children comprising standardization sample of Wechsler Preschool and Primary Scale of Intelligence (WPPSI). Grouped scaled scores from WPPSI subtests according to similar level and shape using sequential minimum-variance cluster analysis with independent replications. Obtained final solution of…

Stellar Populations and Radial Migrations in Virgo Disk Galaxies

NASA Astrophysics Data System (ADS)

Roediger, Joel C.; Courteau, Stéphane; Sánchez-Blázquez, Patricia; McDonald, Michael

2012-10-01

We present new stellar age profiles, derived from well-resolved optical and near-infrared images of 64 Virgo cluster disk galaxies, whose analysis poses a challenge for current disk galaxy formation models. Our ability to break the age-metallicity degeneracy and the significant size of our sample represent key improvements over complementary studies of field disk galaxies. Our results can be summarized as follows: first, and contrary to observations of disk galaxies in the field, these cluster galaxies are distributed almost equally amongst the three main types of disk galaxy luminosity profiles (I/II/III), indicating that the formation and/or survival of Type II breaks is suppressed within the cluster environment. Second, we find examples of statistically significant inversions ("U-shapes") in the age profiles of all three disk galaxy types, reminiscent of predictions from high-resolution simulations of classically truncated Type II disks in the field. These features characterize the age profiles for only about a third (<=36%) of each disk galaxy type in our sample. An even smaller fraction of cluster disks (~11% of the total sample) exhibit age profiles that decrease outward (i.e., negative age gradients). Instead, flat and/or positive age gradients prevail (>=50%) within our Type I, II, and III subsamples. These observations thus suggest that while stellar migrations and inside-out growth can play a significant role in the evolution of all disk galaxy types, other factors contributing to the evolution of galaxies can overwhelm the predicted signatures of these processes. We interpret our observations through a scenario whereby Virgo cluster disk galaxies formed initially like their brethren in the field but which, upon falling into the cluster, were transformed into their present state through external processes linked to the environment (e.g., ram-pressure stripping and harassment). Current disk galaxy formation models, which have largely focused on field galaxies, fail to reproduce these results, thus calling for adequate hydrodynamical simulations of dense galaxy environments if we are to understand cluster disks. The current paper highlights numerous constraints for such simulations. In the Appendix, we confirm the claim by Erwin et al. that Type II breaks are absent in Virgo cluster S0s and discuss the detection of Type III breaks in such galaxies.

Broadband, high-resolution investigation of advanced absorption line shapes at high temperature

NASA Astrophysics Data System (ADS)

Schroeder, Paul J.; Cich, Matthew J.; Yang, Jinyu; Swann, William C.; Coddington, Ian; Newbury, Nathan R.; Drouin, Brian J.; Rieker, Gregory B.

2017-08-01

Spectroscopic studies of planetary atmospheres and high-temperature processes (e.g., combustion) require absorption line-shape models that are accurate over extended temperature ranges. To date, advanced line shapes, like the speed-dependent Voigt and Rautian profiles, have not been tested above room temperature with broadband spectrometers. We investigate pure water vapor spectra from 296 to 1305 K acquired with a dual-frequency comb spectrometer spanning from 6800 to 7200 c m-1 at a point spacing of 0.0033 c m-1 and absolute frequency accuracy of <3.3 ×10-6c m-1 . Using a multispectral fitting analysis, we show that only the speed-dependent Voigt accurately models this temperature range with a single power-law temperature-scaling exponent for the broadening coefficients. Only the data from the analysis using this profile fall within theoretical predictions, suggesting that this mechanism captures the dominant narrowing physics for these high-temperature conditions.

Rovibrational line-shape parameters for H2 in He and new H2-He potential energy surface

NASA Astrophysics Data System (ADS)

Thibault, Franck; Patkowski, Konrad; Żuchowski, Piotr S.; Jóźwiak, Hubert; Ciuryło, Roman; Wcisło, Piotr

2017-11-01

We report a new H2-He potential energy surface that, with respect to the previous one [Bakr et al.(2013)], covers much larger range of H2 stretching and exhibits more accurate asymptotic behavior for large separations between H2 and He. Close-coupling calculations performed on this improved potential energy surface allow us to provide line shape parameters for H2 between 5 and 2000 K for Raman isotropic Q lines and anisotropic Q lines (or electric quadrupole lines) and for vibrational bands from the ground up to v = 5 and rotational quantum numbers up to j = 5 . The parameters provided include the usual pressure -broadening and -shifting coefficients as well as the real and imaginary part of Dicke contribution to the Hess profile. The latter parameters can be readily implemented in other line-shape profiles like the most recent one of Hartmann and Tran.

An improved computer model for prediction of axial gas turbine performance losses

NASA Technical Reports Server (NTRS)

Jenkins, R. M.

1984-01-01

The calculation model performs a rapid preliminary pitchline optimization of axial gas turbine annular flowpath geometry, as well as an initial estimate of blade profile shapes, given only a minimum of thermodynamic cycle requirements. No geometric parameters need be specified. The following preliminary design data are determined: (1) the optimum flowpath geometry, within mechanical stress limits; (2) initial estimates of cascade blade shapes; and (3) predictions of expected turbine performance. The model uses an inverse calculation technique whereby blade profiles are generated by designing channels to yield a specified velocity distribution on the two walls. Velocity distributions are then used to calculate the cascade loss parameters. Calculated blade shapes are used primarily to determine whether the assumed velocity loadings are physically realistic. Model verification is accomplished by comparison of predicted turbine geometry and performance with an array of seven NASA single-stage axial gas turbine configurations.

Laboratory investigation on the role of tubular shaped micro resonators phononic crystal insertion on the absorption coefficient of profiled sound absorber

NASA Astrophysics Data System (ADS)

Yahya, I.; Kusuma, J. I.; Harjana; Kristiani, R.; Hanina, R.

2016-02-01

This paper emphasizes the influence of tubular shaped microresonators phononic crystal insertion on the sound absorption coefficient of profiled sound absorber. A simple cubic and two different bodies centered cubic phononic crystal lattice model were analyzed in a laboratory test procedure. The experiment was conducted by using transfer function based two microphone impedance tube method refer to ASTM E-1050-98. The results show that sound absorption coefficient increase significantly at the mid and high-frequency band (600 - 700 Hz) and (1 - 1.6 kHz) when tubular shaped microresonator phononic crystal inserted into the tested sound absorber element. The increment phenomena related to multi-resonance effect that occurs when sound waves propagate through the phononic crystal lattice model that produce multiple reflections and scattering in mid and high-frequency band which increases the sound absorption coefficient accordingly

Dynamical behavior of surface tension on rotating fluids in low and microgravity environments

NASA Technical Reports Server (NTRS)

Hung, R. J.; Tsao, Y. D.; Hong, B. B.; Leslie, F. W.

1989-01-01

Consideration is given to the time-dependent evolutions of the free surface profile (bubble shapes) of a cylindrical container, partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry in low and microgravity environments. The dynamics of the bubble shapes are calculated for four cases: linear time-dependent functions of spin-up and spin-down in low and microgravity, linear time-dependent functions of increasing and decreasing gravity at high and low rotating cylinder speeds, time-dependent step functions of spin-up and spin-down in low gravity, and sinusoidal function oscillation of the gravity environment in high and low rotating cylinder speeds. It is shown that the computer algorithms developed by Hung et al. (1988) may be used to simulate the profile of time-dependent bubble shapes under variations of centrifugal, capillary, and gravity forces.

A comprehensive method for preliminary design optimization of axial gas turbine stages

NASA Technical Reports Server (NTRS)

Jenkins, R. M.

1982-01-01

A method is presented that performs a rapid, reasonably accurate preliminary pitchline optimization of axial gas turbine annular flowpath geometry, as well as an initial estimate of blade profile shapes, given only a minimum of thermodynamic cycle requirements. No geometric parameters need be specified. The following preliminary design data are determined: (1) the optimum flowpath geometry, within mechanical stress limits; (2) initial estimates of cascade blade shapes; (3) predictions of expected turbine performance. The method uses an inverse calculation technique whereby blade profiles are generated by designing channels to yield a specified velocity distribution on the two walls. Velocity distributions are then used to calculate the cascade loss parameters. Calculated blade shapes are used primarily to determine whether the assumed velocity loadings are physically realistic. Model verification is accomplished by comparison of predicted turbine geometry and performance with four existing single stage turbines.

A Formant Range Profile for Singers.

PubMed

Titze, Ingo R; Maxfield, Lynn M; Walker, Megan C

2017-05-01

Vowel selection is important in differentiating between singing styles. The timbre of the vocal instrument, which is related to its frequency spectrum, is governed by both the glottal sound source and the vowel choices made by singers. Consequently, the ability to modify the vowel space is a measure of how successfully a singer can maintain a desired timbre across a range of pitches. Formant range profiles were produced as a means of quantifying this ability. Seventy-seven subjects (including trained and untrained vocalists) participated, producing vowels with three intended mouth shapes: (1) neutral or speech-like, (2) megaphone-shaped (wide open mouth), and (3) inverted-megaphone-shaped (widened oropharynx with moderate mouth opening). The first and second formant frequencies (F 1 and F 2 ) were estimated with fry phonation for each shape and values were plotted in F1-F2 space. By taking four vowels of a quadrangle /i, æ, a, u/, the resulting area was quantified in kHz 2 (kHz squared) as a measure of the subject's ability to modify their vocal tract for spectral differences. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

A FORMANT RANGE PROFILE FOR SINGERS

PubMed Central

Titze, Ingo R.; Maxfield, Lynn; Walker, Megan

2016-01-01

Vowel selection is important in differentiating between singing styles. The timbre of the vocal instrument, which is related to its frequency spectrum, is governed by both the glottal sound source and the vowel choices made by singers. Consequently, the ability to modify the vowel space is a measure of how successfully a singer can maintain a desired timbre across a range of pitches. Formant range profiles (FRPs) were produced as a means of quantifying this ability. 77 subjects (including trained and untrained vocalists) participated, producing vowels with three intended mouth shapes, (1) neutral or speech-like, (2) megaphone-shaped (wide open mouth), and (3) inverted-megaphone-shaped (widened oropharynx with moderate mouth opening). The first and second formant frequencies (F1 and F2) were estimated with fry phonation for each shape and values were plotted in F1–F2 space. By taking four vowels of a quadrangle /i, æ, a, u/, the resulting area was quantified in kHz2 (kHz squared) as a measure of the subject’s ability to modify their vocal tract for spectral differences. PMID:28029556

Comparison study of cable geometries and superconducting tape layouts for high-temperature superconductor cables

NASA Astrophysics Data System (ADS)

Ta, Wurui; Shao, Tianchong; Gao, Yuanwen

2018-04-01

High-temperature superconductor (HTS) rare-earth-barium-copper-oxide (REBCO) tapes are very promising for use in high-current cables. The cable geometry and the layout of the superconducting tapes are directly related to the performance of the HTS cable. In this paper, we use numerical methods to perform a comparison study of multiple-stage twisted stacked-tape cable (TSTC) conductors to find better cable structures that can both improve the critical current and minimize the alternating current (AC) losses of the cable. The sub-cable geometry is designed to have a stair-step shape. Three superconducting tape layouts are chosen and their transport performance and AC losses are evaluated. The magnetic field and current density profiles of the cables are obtained. The results show that arrangement of the superconducting tapes from the interior towards the exterior of the cable based on their critical current values in descending order can enhance the cable's transport capacity while significantly reducing the AC losses. These results imply that cable transport capacity improvements can be achieved by arranging the superconducting tapes in a manner consistent with the electromagnetic field distribution. Through comparison of the critical currents and AC losses of four types of HTS cables, we determine the best structural choice among these cables.

Studies of Transitional Flow, Unsteady Separation Phenomena and Particle Induced Augmentation Heating on Ablated Nose Tips.

DTIC Science & Technology

1975-10-01

63 29 Variation of Profile Shape with Time for Axisyinmetric Camphor Models 63 30 The Development of Ablated Nose Shapes Over Which Flow...ablation tests using camphor models and inferred from downrange observation of full scale flight missions. Regions of gross instability on nose...been verified in wind tunnel tests of camphor models where shapes similar to those shown on Figure 29 can be developed under transitional conditions

Interpretation of scrape-off layer profile evolution and first-wall ion flux statistics on JET using a stochastic framework based on fillamentary motion

NASA Astrophysics Data System (ADS)

Walkden, N. R.; Wynn, A.; Militello, F.; Lipschultz, B.; Matthews, G.; Guillemaut, C.; Harrison, J.; Moulton, D.; Contributors, JET

2017-08-01

This paper presents the use of a novel modelling technique based around intermittent transport due to filament motion, to interpret experimental profile and fluctuation data in the scrape-off layer (SOL) of JET during the onset and evolution of a density profile shoulder. A baseline case is established, prior to shoulder formation, and the stochastic model is shown to be capable of simultaneously matching the time averaged profile measurement as well as the PDF shape and autocorrelation function from the ion-saturation current time series at the outer wall. Aspects of the stochastic model are then varied with the aim of producing a profile shoulder with statistical measurements consistent with experiment. This is achieved through a strong localised reduction in the density sink acting on the filaments within the model. The required reduction of the density sink occurs over a highly localised region with the timescale of the density sink increased by a factor of 25. This alone is found to be insufficient to model the expansion and flattening of the shoulder region as the density increases, which requires additional changes within the stochastic model. An example is found which includes both a reduction in the density sink and filament acceleration and provides a consistent match to the experimental data as the shoulder expands, though the uniqueness of this solution can not be guaranteed. Within the context of the stochastic model, this implies that the localised reduction in the density sink can trigger shoulder formation, but additional physics is required to explain the subsequent evolution of the profile.

Ultrahigh-resolution spectroscopy with atomic or molecular dark resonances: Exact steady-state line shapes and asymptotic profiles in the adiabatic pulsed regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanon-Willette, Thomas; Clercq, Emeric de; Arimondo, Ennio

2011-12-15

Exact and asymptotic line shape expressions are derived from the semiclassical density matrix representation describing a set of closed three-level {Lambda} atomic or molecular states including decoherences, relaxation rates, and light shifts. An accurate analysis of the exact steady-state dark-resonance profile describing the Autler-Townes doublet, the electromagnetically induced transparency or coherent population trapping resonance, and the Fano-Feshbach line shape leads to the linewidth expression of the two-photon Raman transition and frequency shifts associated to the clock transition. From an adiabatic analysis of the dynamical optical Bloch equations in the weak field limit, a pumping time required to efficiently trap amore » large number of atoms into a coherent superposition of long-lived states is established. For a highly asymmetrical configuration with different decay channels, a strong two-photon resonance based on a lower states population inversion is established when the driving continuous-wave laser fields are greatly unbalanced. When time separated resonant two-photon pulses are applied in the adiabatic pulsed regime for atomic or molecular clock engineering, where the first pulse is long enough to reach a coherent steady-state preparation and the second pulse is very short to avoid repumping into a new dark state, dark-resonance fringes mixing continuous-wave line shape properties and coherent Ramsey oscillations are created. Those fringes allow interrogation schemes bypassing the power broadening effect. Frequency shifts affecting the central clock fringe computed from asymptotic profiles and related to the Raman decoherence process exhibit nonlinear shapes with the three-level observable used for quantum measurement. We point out that different observables experience different shifts on the lower-state clock transition.« less

Assessment of the setup dependence of detector response functions for mega-voltage linear accelerators

PubMed Central

Fox, Christopher; Simon, Tom; Simon, Bill; Dempsey, James F.; Kahler, Darren; Palta, Jatinder R.; Liu, Chihray; Yan, Guanghua

2010-01-01

Purpose: Accurate modeling of beam profiles is important for precise treatment planning dosimetry. Calculated beam profiles need to precisely replicate profiles measured during machine commissioning. Finite detector size introduces perturbations into the measured profiles, which, in turn, impact the resulting modeled profiles. The authors investigate a method for extracting the unperturbed beam profiles from those measured during linear accelerator commissioning. Methods: In-plane and cross-plane data were collected for an Elekta Synergy linac at 6 MV using ionization chambers of volume 0.01, 0.04, 0.13, and 0.65 cm3 and a diode of surface area 0.64 mm2. The detectors were orientated with the stem perpendicular to the beam and pointing away from the gantry. Profiles were measured for a 10×10 cm2 field at depths ranging from 0.8 to 25.0 cm and SSDs from 90 to 110 cm. Shaping parameters of a Gaussian response function were obtained relative to the Edge detector. The Gaussian function was deconvolved from the measured ionization chamber data. The Edge detector profile was taken as an approximation to the true profile, to which deconvolved data were compared. Data were also collected with CC13 and Edge detectors for additional fields and energies on an Elekta Synergy, Varian Trilogy, and Siemens Oncor linear accelerator and response functions obtained. Response functions were compared as a function of depth, SSD, and detector scan direction. Variations in the shaping parameter were introduced and the effect on the resulting deconvolution profiles assessed. Results: Up to 10% setup dependence in the Gaussian shaping parameter occurred, for each detector for a particular plane. This translated to less than a ±0.7 mm variation in the 80%–20% penumbral width. For large volume ionization chambers such as the FC65 Farmer type, where the cavity length to diameter ratio is far from 1, the scan direction produced up to a 40% difference in the shaping parameter between in-plane and cross-plane measurements. This is primarily due to the directional difference in penumbral width measured by the FC65 chamber, which can more than double in profiles obtained with the detector stem parallel compared to perpendicular to the scan direction. For the more symmetric CC13 chamber the variation was only 3% between in-plane and cross-plane measurements. Conclusions: The authors have shown that the detector response varies with detector type, depth, SSD, and detector scan direction. In-plane vs cross-plane scanning can require calculation of a direction dependent response function. The effect of a 10% overall variation in the response function, for an ionization chamber, translates to a small deviation in the penumbra from that of the Edge detector measured profile when deconvolved. Due to the uncertainties introduced by deconvolution the Edge detector would be preferable in obtaining an approximation of the true profile, particularly for field sizes where the energy dependence of the diode can be neglected. However, an averaged response function could be utilized to provide a good approximation of the true profile for large ionization chambers and for larger fields for which diode detectors are not recommended. PMID:20229856

The effects of shockwave profile shape and shock obliquity on spallation in Cu and Ta: kinetic and stress-state effects on damage evolution(u)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, George T

2010-12-14

Widespread research over the past five decades has provided a wealth of experimental data and insight concerning shock hardening and the spallation response of materials subjected to square-topped shock-wave loading profiles. Less quantitative data have been gathered on the effect of direct, in-contact, high explosive (HE)-driven Taylor wave (or triangular-wave) loading profile shock loading on the shock hardening, damage evolution, or spallation response of materials. Explosive loading induces an impulse dubbed a 'Taylor Wave'. This is a significantly different loading history than that achieved by a square-topped impulse in terms of both the pulse duration at a fixed peak pressure,more » and a different unloading strain rate from the peak Hugoniot state achieved. The goal of this research is to quantify the influence of shockwave obliquity on the spallation response of copper and tantalum by subjecting plates of each material to HE-driven sweeping detonation-wave loading and quantify both the wave propagation and the post-mortem damage evolution. This talk will summarize our current understanding of damage evolution during sweeping detonation-wave spallation loading in Cu and Ta and show comparisons to modeling simulations. The spallation responses of Cu and Ta are both shown to be critically dependent on the shockwave profile and the stress-state of the shock. Based on variations in the specifics of the shock drive (pulse shape, peak stress, shock obliquity) and sample geometry in Cu and Ta, 'spall strength' varies by over a factor of two and the details of the mechanisms of the damage evolution is seen to vary. Simplistic models of spallation, such as P{sub min} based on 1-D square-top shock data lack the physics to capture the influence of kinetics on damage evolution such as that operative during sweeping detonation loading. Such considerations are important for the development of predictive models of damage evolution and spallation in metals and alloys.« less

Modeling the Influence of Conductivity Profiles on Red Sprite Formation and Structure

NASA Astrophysics Data System (ADS)

Tonev, P.; Velinov, P.

Strong quasi-electrostatic fields generated in the mesosphere and lower ionosphere after a lightning discharge by a succeeding redistribution of the induced spatial charges, are considered to be responsible for red sprite generation. Factors considered here as important for sprite occurrence and size and shape are the discharge parameters and conductivity profile. Thundercloud charges are assumed to be of hundreds of Coulombs distributed within layers with a horizontal extent of tens (or hundreds) of kilometers as typical for big convective multi-cell systems. Cloud- t o -ground positive strokes, characterized by their charge moment change, are considered, and the large continuing currents are taken into account. The thermal breakdown mechanism is considered as responsible for sprite onset. The conditions under which sprites initially occur (i.e. when atmospheric parameters are not disturbed) and their spatial and temporal characteristics are studied in dependence on the conductivity profiles. A self-consistent analytical modeling is proposed for this purpose. Maxwell equations are applied under quasi-electrostatic conditions, when magnetic field component is neglected and the electric field is assumed to be a potential one. The features of a lightning discharge as well as of conductivity profiles (including the slight anisotropy in lower ionosphere) are taken into account in the model. The conductivity profiles are approximated between 0 and 100 km by stepwise profiles, defined on layered atmosphere with ~100 layers. Horizontal conductivity variations occurring at sprite heights (50-90 km) due to electron heating and ionization are represented in the model by a stepped functions in each layer. Continuity of the electrical current density component normal to each sector boundary is required. Results obtained show that for sprite occurrence in daytime conditions larger lightning charge moment change of the parent discharge is needed and sprites are lower localized than at night. The question is studied under what conditions (concerning the discharge and conductivity parameters) the presence of a `ledge' in the conductivity profile in lower ionosphere can influence the occurrence of a diffuse upper portion of a sprite observed [Barrington-Leigh C.P. and U.S.Inan, Identification of sprites and elves with intensified video and broadband array photometry, J.geophys.Res., 106, A2, 1741-1750, 2001]. Conditions under which features of this diffuse structure can be influenced also by anisotropy in this region, and thus can depend on the local magnetic field orientation, are investigated.

Silk sericin loaded alginate nanoparticles: Preparation and anti-inflammatory efficacy.

PubMed

Khampieng, Thitikan; Aramwit, Pornanong; Supaphol, Pitt

2015-09-01

In this study, silk sericin loaded alginate nanoparticles were prepared by the emulsification method followed by internal crosslinking. The effects of various silk sericin loading concentration on particle size, shape, thermal properties, and release characteristics were investigated. The initial silk sericin loadings of 20, 40, and 80% w/w to polymer were incorporated into these alginate nanoparticles. SEM images showed a spherical shape and small particles of about 71.30-89.50 nm. TGA analysis showed that thermal stability slightly increased with increasing silk sericin loadings. FTIR analysis suggested interactions between alginate and silk sericin in the nanoparticles. The release study was performed in acetate buffer at normal skin conditions (pH 5.5; 32 °C). The release profiles of silk sericin exhibited initial rapid release, consequently with sustained release. These silk sericin loaded alginate nanoparticles were further incorporated into topical hydrogel and their anti-inflammatory properties were studied using carrageenan-induced paw edema assay. The current study confirms the hypothesis that the application of silk sericin loaded alginate nanoparticle gel can inhibit inflammation induced by carrageenan. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantifying the effect of colorization enhancement on mammogram images

NASA Astrophysics Data System (ADS)

Wojnicki, Paul J.; Uyeda, Elizabeth; Micheli-Tzanakou, Evangelia

2002-04-01

Current methods of radiological displays provide only grayscale images of mammograms. The limitation of the image space to grayscale provides only luminance differences and textures as cues for object recognition within the image. However, color can be an important and significant cue in the detection of shapes and objects. Increasing detection ability allows the radiologist to interpret the images in more detail, improving object recognition and diagnostic accuracy. Color detection experiments using our stimulus system, have demonstrated that an observer can only detect an average of 140 levels of grayscale. An optimally colorized image can allow a user to distinguish 250 - 1000 different levels, hence increasing potential image feature detection by 2-7 times. By implementing a colorization map, which follows the luminance map of the original grayscale images, the luminance profile is preserved and color is isolated as the enhancement mechanism. The effect of this enhancement mechanism on the shape, frequency composition and statistical characteristics of the Visual Evoked Potential (VEP) are analyzed and presented. Thus, the effectiveness of the image colorization is measured quantitatively using the Visual Evoked Potential (VEP).

Ionization signals from diamond detectors in fast-neutron fields

NASA Astrophysics Data System (ADS)

Weiss, C.; Frais-Kölbl, H.; Griesmayer, E.; Kavrigin, P.

2016-09-01

In this paper we introduce a novel analysis technique for measurements with single-crystal chemical vapor deposition (sCVD) diamond detectors in fast-neutron fields. This method exploits the unique electronic property of sCVD diamond sensors that the signal shape of the detector current is directly proportional to the initial ionization profile. In fast-neutron fields the diamond sensor acts simultaneously as target and sensor. The interaction of neutrons with the stable isotopes 12 C and 13 C is of interest for fast-neutron diagnostics. The measured signal shapes of detector current pulses are used to identify individual types of interactions in the diamond with the goal to select neutron-induced reactions in the diamond and to suppress neutron-induced background reactions as well as γ-background. The method is verified with experimental data from a measurement in a 14.3 MeV neutron beam at JRC-IRMM, Geel/Belgium, where the 13C(n, α)10Be reaction was successfully extracted from the dominating background of recoil protons and γ-rays and the energy resolution of the 12C(n, α)9Be reaction was substantially improved. The presented analysis technique is especially relevant for diagnostics in harsh radiation environments, like fission and fusion reactors. It allows to extract the neutron spectrum from the background, and is particularly applicable to neutron flux monitoring and neutron spectroscopy.

Realistic respiratory motion margins for external beam partial breast irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conroy, Leigh; Quirk, Sarah; Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4

Purpose: Respiratory margins for partial breast irradiation (PBI) have been largely based on geometric observations, which may overestimate the margin required for dosimetric coverage. In this study, dosimetric population-based respiratory margins and margin formulas for external beam partial breast irradiation are determined. Methods: Volunteer respiratory data and anterior–posterior (AP) dose profiles from clinical treatment plans of 28 3D conformal radiotherapy (3DCRT) PBI patient plans were used to determine population-based respiratory margins. The peak-to-peak amplitudes (A) of realistic respiratory motion data from healthy volunteers were scaled from A = 1 to 10 mm to create respiratory motion probability density functions. Dosemore » profiles were convolved with the respiratory probability density functions to produce blurred dose profiles accounting for respiratory motion. The required margins were found by measuring the distance between the simulated treatment and original dose profiles at the 95% isodose level. Results: The symmetric dosimetric respiratory margins to cover 90%, 95%, and 100% of the simulated treatment population were 1.5, 2, and 4 mm, respectively. With patient set up at end exhale, the required margins were larger in the anterior direction than the posterior. For respiratory amplitudes less than 5 mm, the population-based margins can be expressed as a fraction of the extent of respiratory motion. The derived formulas in the anterior/posterior directions for 90%, 95%, and 100% simulated population coverage were 0.45A/0.25A, 0.50A/0.30A, and 0.70A/0.40A. The differences in formulas for different population coverage criteria demonstrate that respiratory trace shape and baseline drift characteristics affect individual respiratory margins even for the same average peak-to-peak amplitude. Conclusions: A methodology for determining population-based respiratory margins using real respiratory motion patterns and dose profiles in the AP direction was described. It was found that the currently used respiratory margin of 5 mm in partial breast irradiation may be overly conservative for many 3DCRT PBI patients. Amplitude alone was found to be insufficient to determine patient-specific margins: individual respiratory trace shape and baseline drift both contributed to the dosimetric target coverage. With respiratory coaching, individualized respiratory margins smaller than the full extent of motion could reduce planning target volumes while ensuring adequate coverage under respiratory motion.« less

Testing of SIR (a transformable robotic submarine) in Lake Tahoe for future deployment at West Antarctic Ice Sheet grounding lines of Siple Coast

NASA Astrophysics Data System (ADS)

Powell, R. D.; Scherer, R. P.; Griffiths, I.; Taylor, L.; Winans, J.; Mankoff, K. D.

2011-12-01

A remotely operated vehicle (ROV) has been custom-designed and built by DOER Marine to meet scientific requirements for exploring subglacial water cavities. This sub-ice rover (SIR) will explore and quantitatively document the grounding zone areas of the Ross Ice Shelf cavity using a 3km-long umbilical tether by deployment through an 800m-long ice borehole in a torpedo shape, which is also its default mode if operational failure occurs. Once in the ocean cavity it transforms via a diamond-shaped geometry into a rectangular form when all of its instruments come alive in its flight mode. Instrumentation includes 4 cameras (one forward-looking HD), a vertical scanning sonar (long-range imaging for spatial orientation and navigation), Doppler current meter (determine water current velocities), multi-beam sonar (image and swath map bottom topography), sub-bottom profiler (profile sub-sea-floor sediment for geological history), CTD (determine salinity, temperature and depth), DO meter (determine dissolved oxygen content in water), transmissometer (determine suspended particulate concentrations in water), laser particle-size analyzer (determine sizes of particles in water), triple laser-beams (determine size and volume of objects), thermistor probe (measure in situ temperatures of ice and sediment), shear vane probe (determine in situ strength of sediment), manipulator arm (deploy instrumentation packages, collect samples), shallow ice corer (collect ice samples and glacial debris), water sampler (determine sea water/freshwater composition, calibrate real-time sensors, sample microbes), shallow sediment corer (sample sea floor, in-ice and subglacial sediment for stratigraphy, facies, particle size, composition, structure, fabric, microbes). A sophisticated array of data handling, storing and displaying will allow real-time observations and environmental assessments to be made. This robotic submarine and other instruments will be tested in Lake Tahoe in September, 2011 and results will be presented on its trials and geological and biological findings down to the deepest depths of the lake. Other instruments include a 5m-ling percussion corer for sampling deeper sediments, an ice-tethered profiler with CTD and ACDP, and in situ oceanographic mooring designed to fit down a narrow (30cm-diameter) ice borehole that include interchangeable packages of ACDPs, CTDs, transmissometers, laser particle-size analyzer, DO meter, automated multi-port water sampler, water column nutrient analyzer, sediment porewater chemistry analyzer, down-looking color camera (see figure), and altimeter.

SHAPEMOL: the companion to SHAPE in the molecular era of ALMA and HERSCHEL

NASA Astrophysics Data System (ADS)

Santander-García, M.; Bujarrabal, V.; Alcolea, J.

2013-05-01

Modern instrumentation in radioastronomy constitutes a valuable tool for studying the Universe: ALMA will reach unprecedented sensitivities and spatial resolution, while Herschel/HIFI has opened a new window (most of the sub-mm and far infrared ranges are only accessible from space) for probing molecular warm gas (˜50-1000 K), complementing ground-based telescopes, which are better suited to study molecular molecular gas with temperatures under ˜100 K. On the other hand, the SHAPE software has emerged in the last few years as the standard tool for determinging the morphology and velocity field of different kinds of gaseous nebulae (mainly planetary nebulae, protoplanetary nebulae and nebulae around massive stars, although it can also be applied to H II regions and molecular clouds) via spatio-kinematical modelling. Standard SHAPE implements radiative transfer solving, but it is only available for atomic species and not for molecules. Being aware of the growing importance of the development of tools for easying the analyses of molecular data from new era observatories, we introduce the computer code shapemol, a plug-in for SHAPE with which we intend to fill the so far empty molecular niche. shapemol enables spatio-kinematic modeling with accurate non-LTE calculations of line excitation and radiative transfer in molecular species. This code has been succesfully tested in the study of the excitation conditions of the molecular envelope of the planetary nebula NGC 7027 using data from Herschel/HIFI and IRAM 30m. Currently, it allows radiative transfer solving in the ^{12}CO and ^{13}CO J=1-0 to J=17-16 lines. shapemol, used along SHAPE, allows to easily generate synthetic maps to test against interferometric observations, as well as synthetic line profiles to match single-dish observations.

A simplified simulation model for a HPDC die with conformal cooling channels

NASA Astrophysics Data System (ADS)

Frings, Markus; Behr, Marek; Elgeti, Stefanie

2017-10-01

In general, the cooling phase of the high-pressure die casting process is based on complex physical phenomena: so-lidification of molten material; heat exchange between cast part, die and cooling fluid; turbulent flow inside the cooling channels that needs to be considered when computing the heat flux; interdependency of properties and temperature of the cooling liquid. Intuitively understanding and analyzing all of these effects when designing HPDC dies is not feasible. A remedy that has become available is numerical design, based for example on shape optimization methods. However, current computing power is not sufficient to perform optimization while at the same time fully resolving all physical phenomena. But since in HPDC suitable objective functions very often lead to integral values, e.g., average die temperature, this paper identifies possible simplifications in the modeling of the cooling phase. As a consequence, the computational effort is reduced to an acceptable level. A further aspect that arises in the context of shape optimization is the evaluation of shape gradients. The challenge here is to allow for large shape deformations without remeshing. In our approach, the cooling channels are described by their center lines. The flow profile of the cooling fluid is then estimated based on experimental data found in literature for turbulent pipe flows. In combination, the heat flux throughout cavity, die, and cooling channel can be described by one single advection-diffusion equation on a fixed mesh. The parameters in the equation are adjusted based on the position of cavity and cooling channel. Both results contribute towards a computationally efficient, yet accurate method, which can be employed within the frame of shape optimization of cooling channels in HPDC dies.

The kinematics of the molecular gas in Centaurus A

NASA Technical Reports Server (NTRS)

Quillen, A. C.; De Zeeuw, P. T.; Phinney, E. S.; Phillips, T. G.

1992-01-01

The CO (2-1) emission along the inner dust lane of Centaurus A, observed with the Caltech Submillimeter Observatory on Mauna Kea, shows the molecular gas to be in a thin disk, with a velocity dispersion of only about 10 km/s. The observed line profiles are broadened considerably due to beam smearing of the gas velocity field. The profile shapes are inconsistent with planar circular and noncircular motion. However, a warped disk in a prolate potential provides a good fit to the profile shapes. The morphology and kinematics of the molecular gas is similar to that of the ionized material, seen in H-alpha. The best-fitting warped disk model not only matches the optical appearance of the dust lane but also agrees with the large-scale map of the CO emission and is consistent with H I measurements at larger radii.

Noise suppression due to annulus shaping of an inverted-velocity-profile coaxial nozzle. [supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

Goodykoontz, J.; Vonglahn, U.

1980-01-01

An inverted velocity profile coaxial nozzle for use with supersonic cruise aircraft produces less jet noise than an equivalent conical nozzle. Furthermore, decreasing the annulus height (increasing radius ratio with constant flow) results in further noise reduction benefits. The annulus shape (height) was varied by an eccentric mounting of the annular nozzle with respect to a conical core nozzle. Acoustic measurements were made in the flyover plane below the narrowest portion of the annulus and at 90 deg and 180 deg from this point. The model-scale spectra are scaled up to engine size (1.07 m diameter) and the perceived noise levels for the eccentric and baseline concentric inverted velocity profile coaxial nozzles are compared over a range of operating conditions. The implications of the acoustic benefits derived with the eccentric nozzle to practical applications are discussed.

Exact analytical modeling of lightwave propagation in planar media with arbitrarily graded index profiles

NASA Astrophysics Data System (ADS)

Krapez, J.-C.

2018-02-01

Applying the Darboux transformation in the optical-depth space allows building infinite chains of exact analytical solutions of the electromagnetic (EM) fields in planar 1D-graded dielectrics. As a matter of fact, infinite chains of solvable admittance profiles (e.g. refractive-index profiles, in the case of non-magnetic materials), together with the related EM fields are simultaneously and recursively obtained. The whole procedure has received the name "PROFIDT method" for PROperty and FIeld Darboux Transformation method. By repeating the Darboux transformations we can find out progressively more complex profiles and their EM solutions. An alternative is to stop after the first step and settle for a particular class of four-parameter admittance profiles that were dubbed of "sech(ξ)-type". These profiles are highly flexible. For this reason, they can be used as elementary bricks for building and modeling profiles of arbitrary shape. In addition, the corresponding transfer matrix involves only elementary functions. The sub-class of "sech(ξ)-type" profiles with horizontal end-slopes (S-shaped function) is particularly interesting: these can be used for high-level modeling of piecewise-sigmoidal refractive-index profiles encountered in various photonic devices such as matchinglayers, antireflection layers, rugate filters, chirped mirrors and photonic crystals. These simple analytical tools also allow exploring the fascinating properties of a new kind of structure, namely smooth quasicrystals. They can also be applied to model propagation of other types of waves in graded media such as acoustic waves and electric waves in tapered transmission lines.

LABORATORY MEASUREMENTS OF WHITE DWARF PHOTOSPHERIC SPECTRAL LINES: Hβ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Falcon, Ross E.; Gomez, T. A.; Montgomery, M. H.

2015-06-20

We spectroscopically measure multiple hydrogen Balmer line profiles from laboratory plasmas to investigate the theoretical line profiles used in white dwarf (WD) atmosphere models. X-ray radiation produced at the Z Pulsed Power Facility at Sandia National Laboratories initiates plasma formation in a hydrogen-filled gas cell, replicating WD photospheric conditions. Here we present time-resolved measurements of Hβ and fit this line using different theoretical line profiles to diagnose electron density, n{sub e}, and n = 2 level population, n{sub 2}. Aided by synthetic tests, we characterize the validity of our diagnostic method for this experimental platform. During a single experiment, wemore » infer a continuous range of electron densities increasing from n{sub e} ∼ 4 to ∼30 × 10{sup 16} cm{sup −3} throughout a 120-ns evolution of our plasma. Also, we observe n{sub 2} to be initially elevated with respect to local thermodynamic equilibrium (LTE); it then equilibrates within ∼55 ns to become consistent with LTE. This supports our electron-temperature determination of T{sub e} ∼ 1.3 eV (∼15,000 K) after this time. At n{sub e} ≳ 10{sup 17} cm{sup −3}, we find that computer-simulation-based line-profile calculations provide better fits (lower reduced χ{sup 2}) than the line profiles currently used in the WD astronomy community. The inferred conditions, however, are in good quantitative agreement. This work establishes an experimental foundation for the future investigation of relative shapes and strengths between different hydrogen Balmer lines.« less

Advances in the steady-state hybrid regime in DIII-D—a fully non-inductive, ELM-suppressed scenario for ITER

NASA Astrophysics Data System (ADS)

Petty, C. C.; Nazikian, R.; Park, J. M.; Turco, F.; Chen, Xi; Cui, L.; Evans, T. E.; Ferraro, N. M.; Ferron, J. R.; Garofalo, A. M.; Grierson, B. A.; Holcomb, C. T.; Hyatt, A. W.; Kolemen, E.; La Haye, R. J.; Lasnier, C.; Logan, N.; Luce, T. C.; McKee, G. R.; Orlov, D.; Osborne, T. H.; Pace, D. C.; Paz-Soldan, C.; Petrie, T. W.; Snyder, P. B.; Solomon, W. M.; Taylor, N. Z.; Thome, K. E.; Van Zeeland, M. A.; Zhu, Y.

2017-11-01

The hybrid regime with beta, collisionality, safety factor and plasma shape relevant to the ITER steady-state mission has been successfully integrated with ELM suppression by applying an odd parity n  =  3 resonant magnetic perturbation (RMP). Fully non-inductive hybrids in the DIII-D tokamak with high beta (≤ft< β \\right>   ⩽  2.8%) and high confinement (H98y2  ⩽  1.4) in the ITER similar shape have achieved zero surface loop voltage for up to two current relaxation times using efficient central current drive from ECCD and NBCD. The n  =  3 RMP causes surprisingly little increase in thermal transport during ELM suppression. Poloidal magnetic flux pumping in hybrid plasmas maintains q above 1 without loss of current drive efficiency, except that experiments show that extremely peaked ECCD profiles can create sawteeth. During ECCD, Alfvén eigenmode (AE) activity is replaced by a more benign fishbone-like mode, reducing anomalous beam ion diffusion by a factor of 2. While the electron and ion thermal diffusivities substantially increase with higher ECCD power, the loss of confinement can be offset by the decreased fast ion transport resulting from AE suppression. Extrapolations from DIII-D along a dimensionless parameter scaling path as well as those using self-consistent theory-based modeling show that these ELM-suppressed, fully non-inductive hybrids can achieve the Q fus  =  5 ITER steady-state mission.

Chip-carrier thermal barrier and its impact on lateral thermal lens profile and beam parameter product in high power broad area lasers

NASA Astrophysics Data System (ADS)

Rieprich, J.; Winterfeldt, M.; Kernke, R.; Tomm, J. W.; Crump, P.

2018-03-01

High power broad area diode lasers with high optical power density in a small focus spot are in strong commercial demand. For this purpose, the beam quality, quantified via the beam parameter product (BPP), has to be improved. Previous studies have shown that the BPP is strongly affected by current-induced heating and the associated thermal lens formed within the laser stripe. However, the chip structure and module-assembly related factors that regulate the size and the shape of the thermal lens are not well known. An experimental infrared thermographic technique is used to quantify the thermal lens profile in diode lasers operating at an emission wavelength of 910 nm, and the results are compared with finite element method simulations. The analysis indicates that the measured thermal profiles can best be explained when a thermal barrier is introduced between the chip and the carrier, which is shown to have a substantial impact on the BPP and the thermal resistance. Comparable results are observed in further measurements of samples from multiple vendors, and the barrier is only observed for junction-down (p-down) mounting, consistent with the barrier being associated with the GaAs-metal transition.

Role of spike-frequency adaptation in shaping neuronal response to dynamic stimuli.

PubMed

Peron, Simon Peter; Gabbiani, Fabrizio

2009-06-01

Spike-frequency adaptation is the reduction of a neuron's firing rate to a stimulus of constant intensity. In the locust, the Lobula Giant Movement Detector (LGMD) is a visual interneuron that exhibits rapid adaptation to both current injection and visual stimuli. Here, a reduced compartmental model of the LGMD is employed to explore adaptation's role in selectivity for stimuli whose intensity changes with time. We show that supralinearly increasing current injection stimuli are best at driving a high spike count in the response, while linearly increasing current injection stimuli (i.e., ramps) are best at attaining large firing rate changes in an adapting neuron. This result is extended with in vivo experiments showing that the LGMD's response to translating stimuli having a supralinear velocity profile is larger than the response to constant or linearly increasing velocity translation. Furthermore, we show that the LGMD's preference for approaching versus receding stimuli can partly be accounted for by adaptation. Finally, we show that the LGMD's adaptation mechanism appears well tuned to minimize sensitivity for the level of basal input.

Shape Optimization for Navier-Stokes Equations with Algebraic Turbulence Model: Numerical Analysis and Computation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haslinger, Jaroslav, E-mail: hasling@karlin.mff.cuni.cz; Stebel, Jan, E-mail: stebel@math.cas.cz

2011-04-15

We study the shape optimization problem for the paper machine headbox which distributes a mixture of water and wood fibers in the paper making process. The aim is to find a shape which a priori ensures the given velocity profile on the outlet part. The mathematical formulation leads to the optimal control problem in which the control variable is the shape of the domain representing the header, the state problem is represented by the generalized Navier-Stokes system with nontrivial boundary conditions. This paper deals with numerical aspects of the problem.

Ideal-Magnetohydrodynamic-Stable Tilting in Field-Reversed Configurations

NASA Astrophysics Data System (ADS)

Kanno, Ryutaro; Ishida, Akio; Steinhauer, Loren

1995-02-01

The tilting mode in field-reversed configurations (FRC) is examined using ideal-magnetohydrodynamic stability theory. Tilting, a global mode, is the greatest threat for disruption of FRC confinement. Previous studies uniformly found tilting to be unstable in ideal theory: the objective here is to ascertain if stable equilibria were overlooked in past work. Solving the variational problem with the Rayleigh-Ritz technique, tilting-stable equilibria are found for sufficiently hollow current profile and sufficient racetrackness of the separatrix shape. Although these equilibria were not examined previously, the present conclusion is quite surprising. Consequently checks of the method are offered. Even so it cannot yet be claimed with complete certainty that stability has been proved: absolute confirmation of ideal-stable tilting awaits the application of more complete methods.

Algebraic motion of vertically displacing plasmas

NASA Astrophysics Data System (ADS)

Pfefferlé, D.; Bhattacharjee, A.

2018-02-01

The vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to come in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear "sinking" behaviour shown to be algebraic and decelerating. The acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.

Airfoil shape for a turbine nozzle

DOEpatents

Burdgick, Steven Sebastian; Patik, Joseph Francis; Itzel, Gary Michael

2002-01-01

A first-stage nozzle vane includes an airfoil having a profile according to Table I. The annulus profile of the hot gas path is defined in conjunction with the airfoil profile and the profile of the inner and outer walls by the Cartesian coordinate values given in Tables I and II, respectively. The airfoil is a three-dimensional bowed design, both in the airfoil body and in the trailing edge. The airfoil is steam and air-cooled by flowing cooling mediums through cavities extending in the vane between inner and outer walls.

Constraints on Porosity and Mass Loss in O-star Winds from the Modeling of X-ray Emission Line Profile Shapes

NASA Technical Reports Server (NTRS)

Leutenegger, Maurice A.; Cohen, David H.; Sundqvist, Jon O.; Owocki, Stanley P.

2013-01-01

We fit X-ray emission line profiles in high resolution XMM-Newton and Chandra grating spectra of the early O supergiant Zeta Pup with models that include the effects of porosity in the stellar wind. We explore the effects of porosity due to both spherical and flattened clumps. We find that porosity models with flattened clumps oriented parallel to the photosphere provide poor fits to observed line shapes. However, porosity models with isotropic clumps can provide acceptable fits to observed line shapes, but only if the porosity effect is moderate. We quantify the degeneracy between porosity effects from isotropic clumps and the mass-loss rate inferred from the X-ray line shapes, and we show that only modest increases in the mass-loss rate (40%) are allowed if moderate porosity effects (h(sub infinity) less than approximately R(sub *)) are assumed to be important. Large porosity lengths, and thus strong porosity effects, are ruled out regardless of assumptions about clump shape. Thus, X-ray mass-loss rate estimates are relatively insensitive to both optically thin and optically thick clumping. This supports the use of X-ray spectroscopy as a mass-loss rate calibration for bright, nearby O stars

Shape-programmable magnetic soft matter

PubMed Central

Lum, Guo Zhan; Ye, Zhou; Dong, Xiaoguang; Marvi, Hamid; Erin, Onder; Hu, Wenqi; Sitti, Metin

2016-01-01

Shape-programmable matter is a class of active materials whose geometry can be controlled to potentially achieve mechanical functionalities beyond those of traditional machines. Among these materials, magnetically actuated matter is particularly promising for achieving complex time-varying shapes at small scale (overall dimensions smaller than 1 cm). However, previous work can only program these materials for limited applications, as they rely solely on human intuition to approximate the required magnetization profile and actuating magnetic fields for their materials. Here, we propose a universal programming methodology that can automatically generate the required magnetization profile and actuating fields for soft matter to achieve new time-varying shapes. The universality of the proposed method can therefore inspire a vast number of miniature soft devices that are critical in robotics, smart engineering surfaces and materials, and biomedical devices. Our proposed method includes theoretical formulations, computational strategies, and fabrication procedures for programming magnetic soft matter. The presented theory and computational method are universal for programming 2D or 3D time-varying shapes, whereas the fabrication technique is generic only for creating planar beams. Based on the proposed programming method, we created a jellyfish-like robot, a spermatozoid-like undulating swimmer, and an artificial cilium that could mimic the complex beating patterns of its biological counterpart. PMID:27671658

Shape-programmable magnetic soft matter.

PubMed

Lum, Guo Zhan; Ye, Zhou; Dong, Xiaoguang; Marvi, Hamid; Erin, Onder; Hu, Wenqi; Sitti, Metin

2016-10-11

Shape-programmable matter is a class of active materials whose geometry can be controlled to potentially achieve mechanical functionalities beyond those of traditional machines. Among these materials, magnetically actuated matter is particularly promising for achieving complex time-varying shapes at small scale (overall dimensions smaller than 1 cm). However, previous work can only program these materials for limited applications, as they rely solely on human intuition to approximate the required magnetization profile and actuating magnetic fields for their materials. Here, we propose a universal programming methodology that can automatically generate the required magnetization profile and actuating fields for soft matter to achieve new time-varying shapes. The universality of the proposed method can therefore inspire a vast number of miniature soft devices that are critical in robotics, smart engineering surfaces and materials, and biomedical devices. Our proposed method includes theoretical formulations, computational strategies, and fabrication procedures for programming magnetic soft matter. The presented theory and computational method are universal for programming 2D or 3D time-varying shapes, whereas the fabrication technique is generic only for creating planar beams. Based on the proposed programming method, we created a jellyfish-like robot, a spermatozoid-like undulating swimmer, and an artificial cilium that could mimic the complex beating patterns of its biological counterpart.

Shape-programmable magnetic soft matter

NASA Astrophysics Data System (ADS)

Zhan Lum, Guo; Ye, Zhou; Dong, Xiaoguang; Marvi, Hamid; Erin, Onder; Hu, Wenqi; Sitti, Metin

2016-10-01

Shape-programmable matter is a class of active materials whose geometry can be controlled to potentially achieve mechanical functionalities beyond those of traditional machines. Among these materials, magnetically actuated matter is particularly promising for achieving complex time-varying shapes at small scale (overall dimensions smaller than 1 cm). However, previous work can only program these materials for limited applications, as they rely solely on human intuition to approximate the required magnetization profile and actuating magnetic fields for their materials. Here, we propose a universal programming methodology that can automatically generate the required magnetization profile and actuating fields for soft matter to achieve new time-varying shapes. The universality of the proposed method can therefore inspire a vast number of miniature soft devices that are critical in robotics, smart engineering surfaces and materials, and biomedical devices. Our proposed method includes theoretical formulations, computational strategies, and fabrication procedures for programming magnetic soft matter. The presented theory and computational method are universal for programming 2D or 3D time-varying shapes, whereas the fabrication technique is generic only for creating planar beams. Based on the proposed programming method, we created a jellyfish-like robot, a spermatozoid-like undulating swimmer, and an artificial cilium that could mimic the complex beating patterns of its biological counterpart.

Aerodynamically-Actuated Radical Shape-Change Concept

NASA Technical Reports Server (NTRS)

Ivanco, Thomas G.; Ivanco, Marie L.; Ancel, Ersin; Grubb, Amanda L.; Prasad, Supranamaaya

2017-01-01

Aerodynamically-actuated radical shape change (AARSC) is a novel concept that enables flight vehicles to conduct a mission profile containing radically different flight regimes while possibly mitigating the typical penalties incurred by radical geometric change. Weight penalties are mitigated by utilizing a primary flight control to generate aerodynamic loads that then drive a shape-change actuation. The flight mission profile used to analyze the AARSC concept is that of a transport aircraft that cruises at a lower altitude than typical transports. Based upon a preliminary analysis, substantial fuel savings are realized for mission ranges below 2000 NM by comparison to a state-of-the-art baseline, with an increasing impact as mission range is reduced. The predicted savings are so significant at short-haul ranges that the shape-change concept rivals the fuel-burn performance of turboprop aircraft while completing missions in less time than typical jet aircraft. Lower-altitude cruise has also been sought after in recent years for environmental benefits, however, the performance penalty to conventional aircraft was prohibitive. AARSC may enable the opportunity to realize the environmental benefits of lower-altitude emissions coupled with mission fuel savings. The findings of this study also reveal that the AARSC concept appears to be controllable, turbulence susceptibility is likely not an issue, and the shape change concept appears to be mechanically and aerodynamically feasible.

Vertical Structure of Ice Cloud Layers From CloudSat and CALIPSO Measurements and Comparison to NICAM Simulations

NASA Technical Reports Server (NTRS)

Ham, Seung-Hee; Sohn, Byung-Ju; Kato, Seiji; Satoh, Masaki

2013-01-01

The shape of the vertical profile of ice cloud layers is examined using 4 months of CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) global measurements taken on January, April, July, and October 2007. Ice clouds are selected using temperature profiles when the cloud base is located above the 253K temperature level. The obtained ice water content (IWC), effective radius, or extinction coefficient profiles are normalized by their layer mean values and are expressed in the normalized vertical coordinate, which is defined as 0 and 1 at the cloud base and top heights, respectively. Both CloudSat and CALIPSO observations show that the maximum in the IWC and extinction profiles shifts toward the cloud bottom, as the cloud depth increases. In addition, clouds with a base reaching the surface in a high-latitude region show that the maximum peak of the IWC and extinction profiles occurs near the surface, which is presumably due to snow precipitation. CloudSat measurements show that the seasonal difference in normalized cloud vertical profiles is not significant, whereas the normalized cloud vertical profile significantly varies depending on the cloud type and the presence of precipitation. It is further examined if the 7 day Nonhydrostatic Icosahedral Atmospheric Model (NICAM) simulation results from 25 December 2006 to 1 January 2007 generate similar cloud profile shapes. NICAM IWC profiles also show maximum peaks near the cloud bottom for thick cloud layers and maximum peaks at the cloud bottom for low-level clouds near the surface. It is inferred that oversized snow particles in the NICAM cloud scheme produce a more vertically inhomogeneous IWC profile than observations due to quick sedimentation.

Sand waves on an epicontinental shelf: Northern Bering Sea

USGS Publications Warehouse

Field, M.E.; Nelson, C.H.; Cacchione, D.A.; Drake, D.E.

1981-01-01

Sand waves and current ripples occupy the crests and flanks of a series of large linear sand ridges (20 km ?? 5 km ?? 10 m high) lying in an open-marine setting in the northern Bering Sea. The sand wave area, which lies west of Seward Peninsula and southeast of Bering Strait, is exposed to the strong continuous flow of coastal water northward toward Bering Strait. A hierarchy of three sizes of superimposed bedforms, all facing northward, was observed in successive cruises in 1976 and 1977. Large sand waves (height 2 m; spacing 200 m) have smaller sand waves (height 1 m; spacing 20 m) lying at a small oblique angle on their stoss slopes. The smaller sand waves in turn have linguoid ripples on their stoss slopes. Repeated studies of the sand wave fields were made both years with high-resolution seismic-reflection profiles, side-scan sonographs, underwater photographs, current-meter stations, vibracores, and suspended-sediment samplers. Comparison of seismic and side-scan data collected along profile lines run both years showed changes in sand wave shape that indicate significant bedload transport within the year. Gouge marks made in sediment by keels of floating ice also showed significantly different patterns each year, further documenting modification to the bottom by sediment transport. During calm sea conditions in 1977, underwater video and camera observations showed formation and active migration of linguoid and straight-crested current ripples. Current speeds 1 m above the bottom were between 20 and 30 cm/s. Maximum current velocities and sand wave migration apparently occur when strong southwesterly winds enhance the steady northerly flow of coastal water. Many cross-stratified sand bodies in the geologic record are interpreted as having formed in a tidal- or storm-dominated setting. This study provides an example of formation and migration of large bedforms by the interaction of storms with strong uniform coastal currents in an open-marine setting. ?? 1981.

Production of Lightning NO(x) and its Vertical Distribution Calculated from 3-D Cloud-scale Chemical Transport Model Simulations

NASA Technical Reports Server (NTRS)

Ott, Lesley; Pickering, Kenneth; Stenchikov, Georgiy; Allen, Dale; DeCaria, Alex; Ridley, Brian; Lin, Ruei-Fong; Lang, Steve; Tao, Wei-Kuo

2009-01-01

A 3-D cloud scale chemical transport model that includes a parameterized source of lightning NO(x), based on observed flash rates has been used to simulate six midlatitude and subtropical thunderstorms observed during four field projects. Production per intracloud (P(sub IC) and cloud-to-ground (P(sub CG)) flash is estimated by assuming various values of P(sub IC) and P(sub CG) for each storm and determining which production scenario yields NO(x) mixing ratios that compare most favorably with in-cloud aircraft observations. We obtain a mean P(sub CG) value of 500 moles NO (7 kg N) per flash. The results of this analysis also suggest that on average, P(sub IC) may be nearly equal to P(sub CG), which is contrary to the common assumption that intracloud flashes are significantly less productive of NO than are cloud-to-ground flashes. This study also presents vertical profiles of the mass of lightning NO(x), after convection based on 3-D cloud-scale model simulations. The results suggest that following convection, a large percentage of lightning NO(x), remains in the middle and upper troposphere where it originated, while only a small percentage is found near the surface. The results of this work differ from profiles calculated from 2-D cloud-scale model simulations with a simpler lightning parameterization that were peaked near the surface and in the upper troposphere (referred to as a "C-shaped" profile). The new model results (a backward C-shaped profile) suggest that chemical transport models that assume a C-shaped vertical profile of lightning NO(x) mass may place too much mass neat the surface and too little in the middle troposphere.

Tuning donut profile for spatial resolution in stimulated emission depletion microscopy.

PubMed

Neupane, Bhanu; Chen, Fang; Sun, Wei; Chiu, Daniel T; Wang, Gufeng

2013-04-01

In stimulated emission depletion (STED)-based or up-conversion depletion-based super-resolution optical microscopy, the donut-shaped depletion beam profile is of critical importance to its resolution. In this study, we investigate the transformation of the donut-shaped depletion beam focused by a high numerical aperture (NA) microscope objective, and model STED point spread function (PSF) as a function of donut beam profile. We show experimentally that the intensity profile of the dark kernel of the donut can be approximated as a parabolic function, whose slope is determined by the donut beam size before the objective back aperture, or the effective NA. Based on this, we derive the mathematical expression for continuous wave (CW) STED PSF as a function of focal plane donut and excitation beam profiles, as well as dye properties. We find that the effective NA and the residual intensity at the center are critical factors for STED imaging quality and the resolution. The effective NA is critical for STED resolution in that it not only determines the donut shape but also the area the depletion laser power is dispersed. An improperly expanded depletion beam will have negligible improvement in resolution. The polarization of the depletion beam also plays an important role as it affects the residual intensity in the center of the donut. Finally, we construct a CW STED microscope operating at 488 nm excitation and 592 nm depletion with a resolution of 70 nm. Our study provides detailed insight to the property of donut beam, and parameters that are important for the optimal performance of STED microscopes. This paper will provide a useful guide for the construction and future development of STED microscopes.

The Relationship between Ionospheric Slab Thickness and the Peak Density Height, hmF2

NASA Astrophysics Data System (ADS)

Meehan, J.; Sojka, J. J.

2017-12-01

The electron density profile is one of the most critical elements in the ionospheric modeling-related applications today. Ionosphere parameters, hmF2, the height of the peak density layer, and slab thickness, the ratio of the total electron content, TEC, to the peak density value, NmF2, are generally obtained from any global sounding observation network and are easily incorporated into models, theoretical or empirical, as numerical representations. Slab thickness is a convenient one-parameter summary of the electron density profile and can relate a variety of elements of interest that effect the overall electron profile shape, such as the neutral and ionospheric temperatures and gradients, the ionospheric composition, and dynamics. Using ISR data from the 2002 Millstone Hill ISR data campaign, we found, for the first time, slab thickness to be correlated to hmF2. For this, we introduce a new ionospheric index, k, which ultimately relates electron density parameters and can be a very useful tool for describing the topside ionosphere shape. Our study is an initial one location, one season, 30-day study, and future work is needed to verify the robustness of our claim. Generally, the ionospheric profile shape, requires knowledge of several ionospheric parameters: electron, ion and neutral temperatures, ion composition, electric fields, and neutral winds, and is dependent upon seasons, local time, location, and the level of solar and geomagnetic activity; however, with this new index, only readily-available, ionospheric density information is needed. Such information, as used in this study, is obtained from a bottomside electron density profile provided by an ionosonde, and TEC data provided by a local, collocated GPS receiver.

Iceberg and ice-keel ploughmarks on the Gdansk-Gotland Sill (south-eastern Baltic Sea)

NASA Astrophysics Data System (ADS)

Dorokhov, D. V.; Dorokhova, E. V.; Sivkov, V. V.

2018-02-01

New interpretation of the undulating moraine relief of the Gdansk-Gotland Sill, Baltic Sea is proposed. Relict iceberg and ice-keel ploughmarks were observed based on the integration of recently acquired side-scan sonar, multi-beam, single-beam and lithological data. The most likely time of their formation is the period of fast Scandinavian sheet retreat occurring from approximately 13.2 to 11.7 ka. Weak erosional-accumulative processes on the sill from 11.7 ka until the present favoured preservation of the iceberg ploughmarks. The predominant directions of the ploughmarks (north-south and northwest-southeast) coincide with the major iceberg (ice) drift direction from the Scandinavian ice sheet. Furrow width varies from 1 to 300 m with a main width of 20-60 m in a depth range of 1 to 10 m (mostly 2-4 m depth). The ploughmarks are flanked by side ridges 0.5-2 m high, and there is a push mound at the end of some furrows. Three types of cross-sectional furrow profiles have been distinguished: V-shaped cross-section profiles would have been formed by a peaked iceberg keel, U-shaped profiles by a flat keel, and W-shaped profiles by double-keel icebergs (ice ridges). The wide local depressions at the end of ploughmarks could have been formed during periods of fast falling of the Baltic Ice Lake water level, when the ice ridges (stamukhi) or icebergs could ground into the seafloor.

Finger tracking for hand-held device interface using profile-matching stereo vision

NASA Astrophysics Data System (ADS)

Chang, Yung-Ping; Lee, Dah-Jye; Moore, Jason; Desai, Alok; Tippetts, Beau

2013-01-01

Hundreds of millions of people use hand-held devices frequently and control them by touching the screen with their fingers. If this method of operation is being used by people who are driving, the probability of deaths and accidents occurring substantially increases. With a non-contact control interface, people do not need to touch the screen. As a result, people will not need to pay as much attention to their phones and thus drive more safely than they would otherwise. This interface can be achieved with real-time stereovision. A novel Intensity Profile Shape-Matching Algorithm is able to obtain 3-D information from a pair of stereo images in real time. While this algorithm does have a trade-off between accuracy and processing speed, the result of this algorithm proves the accuracy is sufficient for the practical use of recognizing human poses and finger movement tracking. By choosing an interval of disparity, an object at a certain distance range can be segmented. In other words, we detect the object by its distance to the cameras. The advantage of this profile shape-matching algorithm is that detection of correspondences relies on the shape of profile and not on intensity values, which are subjected to lighting variations. Based on the resulting 3-D information, the movement of fingers in space from a specific distance can be determined. Finger location and movement can then be analyzed for non-contact control of hand-held devices.

Shape Optimization for Navier-Stokes Equations with Algebraic Turbulence Model: Existence Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bulicek, Miroslav; Haslinger, Jaroslav; Malek, Josef

2009-10-15

We study a shape optimization problem for the paper machine headbox which distributes a mixture of water and wood fibers in the paper making process. The aim is to find a shape which a priori ensures the given velocity profile on the outlet part. The mathematical formulation leads to an optimal control problem in which the control variable is the shape of the domain representing the header, the state problem is represented by a generalized stationary Navier-Stokes system with nontrivial mixed boundary conditions. In this paper we prove the existence of solutions both to the generalized Navier-Stokes system and tomore » the shape optimization problem.« less

EFFECTS OF LEAF AREA PROFILES AND CANOPY STRATIFICATION ON SIMULATED ENERGY FLUXES: THE PROBLEM OF VERTICAL SPATIAL SCALE. (R827676)

EPA Science Inventory

We investigated the effects of the shape of leaf area profiles and the number of canopy layers on simulated sensible and latent heat fluxes using a gradient diffusion-based biometeorological model. Three research questions were addressed through simulation experiments: (1) Given ...

The Strong Ring: A Basic Interest Model of Occupational Structure

ERIC Educational Resources Information Center

Armstrong, Patrick Ian; Smith, Thomas J.; Donnay, David A. C.; Rounds, James

2004-01-01

A classification system and spatial map of occupations were developed using the Basic Interest Scale profiles of 198 occupational incumbent samples (31,010 women; 32,421 men) from the Strong Interest Inventory. Profile shape was found to be similar for incumbents of both genders, allowing for an analysis of combined-gender samples. Using…

The impact of shape memory test on degradation profile of a bioresorbable polymer.

PubMed

Musioł, Marta; Jurczyk, Sebastian; Kwiecień, Michał; Smola-Dmochowska, Anna; Domański, Marian; Janeczek, Henryk; Włodarczyk, Jakub; Klim, Magdalena; Rydz, Joanna; Kawalec, Michał; Sobota, Michał

2018-05-01

The semicrystalline poly(L-lactide) (PLLA) belongs to the materials with shape memory effect (SME) and as a bioresorbable and biocompatible polymer it have found many applications in medical and pharmaceutical field. Assessment of the SME impact on the polymer degradation profile plays crucial role in applications such as drug release systems or in regenerative medicine. Herein, the results of in vitro degradation studies of PLLA samples after SME full test cycle are presented. The samples were loaded and deformed in two manners: progressive and non-progressive. The performed experiments illustrate also influence of the material mechanical damages, caused e.g. during incorrect implantation of PLLA product, on hydrolytic degradation profile. Apparently, degradation profiles are significantly different for the material which was not subjected to the deformation and the deformed ones. The materials after deformation of 50% (in SME cycle) was characterized by non-reversible morphology changes. The effect was observed in deformed samples during the SME test which were carried out ten times. Copyright © 2018 Elsevier Ltd. All rights reserved.

Monte Carlo study for designing a dedicated “D”-shaped collimator used in the external beam radiotherapy of retinoblastoma patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayorga, P. A.; Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada; Brualla, L.

2014-01-15

Purpose: Retinoblastoma is the most common intraocular malignancy in the early childhood. Patients treated with external beam radiotherapy respond very well to the treatment. However, owing to the genotype of children suffering hereditary retinoblastoma, the risk of secondary radio-induced malignancies is high. The University Hospital of Essen has successfully treated these patients on a daily basis during nearly 30 years using a dedicated “D”-shaped collimator. The use of this collimator that delivers a highly conformed small radiation field, gives very good results in the control of the primary tumor as well as in preserving visual function, while it avoids themore » devastating side effects of deformation of midface bones. The purpose of the present paper is to propose a modified version of the “D”-shaped collimator that reduces even further the irradiation field with the scope to reduce as well the risk of radio-induced secondary malignancies. Concurrently, the new dedicated “D”-shaped collimator must be easier to build and at the same time produces dose distributions that only differ on the field size with respect to the dose distributions obtained by the current collimator in use. The scope of the former requirement is to facilitate the employment of the authors' irradiation technique both at the authors' and at other hospitals. The fulfillment of the latter allows the authors to continue using the clinical experience gained in more than 30 years. Methods: The Monte Carlo codePENELOPE was used to study the effect that the different structural elements of the dedicated “D”-shaped collimator have on the absorbed dose distribution. To perform this study, the radiation transport through a Varian Clinac 2100 C/D operating at 6 MV was simulated in order to tally phase-space files which were then used as radiation sources to simulate the considered collimators and the subsequent dose distributions. With the knowledge gained in that study, a new, simpler, “D”-shaped collimator is proposed. Results: The proposed collimator delivers a dose distribution which is 2.4 cm wide along the inferior-superior direction of the eyeball. This width is 0.3 cm narrower than that of the dose distribution obtained with the collimator currently in clinical use. The other relevant characteristics of the dose distribution obtained with the new collimator, namely, depth doses at clinically relevant positions, penumbrae width, and shape of the lateral profiles, are statistically compatible with the results obtained for the collimator currently in use. Conclusions: The smaller field size delivered by the proposed collimator still fully covers the planning target volume with at least 95% of the maximum dose at a depth of 2 cm and provides a safety margin of 0.2 cm, so ensuring an adequate treatment while reducing the irradiated volume.« less

Profiles in Renewable Energy: Case Studies of Successful Utility-Sector

Science.gov Websites

Shape of Renewable Energy Technologies Today Biomass Wood-Burning Plant Reduces Air Pollution Kettle Economical Altamont Pass Windplants U.S. Windpower, Inc. For More Information The Shape of Renewable Energy temperatures >175 degrees C), which rely on flashing the hot water to steam, and binary plants (for resource

Flat profile laser beam shaper

DOEpatents

Johnson, Todd R.

2017-09-12

A system for shaping a beam comprises an emitter for emitting coherent electromagnetic radiation. Birefringent displacers are configured between the emitter and a target wherein the at least two birefringent displacers split the coherent electromagnetic radiation into a plurality of coherent parallel beams of electromagnetic radiation thereby producing a shaped wave front of the coherent parallel beams of electromagnetic radiation.

Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

USGS Publications Warehouse

Obelcz, Jeffrey; Brothers, Daniel S.; Chaytor, Jason D.; ten Brink, Uri S.; Ross, Steve W.; Brooke, Sandra

2013-01-01

Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only subtle modification by Holocene processes active during the present sea-level high-stand.

Nanosized soy phytosome-based thermogel as topical anti-obesity formulation: an approach for acceptable level of evidence of an effective novel herbal weight loss product.

PubMed

El-Menshawe, Shahira F; Ali, Adel A; Rabeh, Mohamed A; Khalil, Nermeen M

2018-01-01

Herbal supplements are currently available as a safer alternative to manage obesity, which has become a rising problem over the recent years. Many chemical drugs on the market are designed to prevent or manage obesity but high cost, low efficacy, and multiple side effects limit its use. Nano lipo-vesicles phytosomal thermogel of Soybean, Glycine max ( L .) Merrill, was formulated and evaluated in an attempt to investigate its anti-obesity action on body weight gain, adipose tissue size, and lipid profile data. Three different techniques were used to prepare phytosome formulations including solvent evaporation, cosolvency, and salting out. The optimized phytosome formulation was then selected using Design Expert ® (version 7.0.0) depending on the highest entrapment efficiency, minimum particle size (PS), and maximum drug release within 2 hours as responses for further evaluation. The successful phytosome complex formation was investigated by means of Fourier-transform infrared spec troscopy and determination of PS and zeta potential. Phytosome vesicles' shape was evaluated using transmission electron microscope to ensure its spherical shape. After characterization of the optimized phytosome formulation, it was incorporated into a thermogel formulation. The obtained phytosomal thermogel formulation was evaluated for its clarity, homogeneity, pH, and gel transformation temperature besides rheology behavior and permeation study. An in vivo study was done to investigate the anti-weight-gain effect of soy phytosomal ther mogel. EE was found to be >99% for all formulations, PS ranging from 51.66-650.67 while drug release was found to be (77.61-99.78) in range. FTIR and TEM results confirmed the formation of phytosome complex. In vivo study showed a marked reduction in body weight, adipose tissue weight and lipid profile. Concisely, soy phytosomal thermogel was found to have a local anti-obesity effect on the abdomen of experimental male albino rats with a slight systemic effect on the lipid profile data.

Profiles of childhood adversities in pathological gamblers - A latent class analysis.

PubMed

Lotzin, Annett; Ulas, Mehmet; Buth, Sven; Milin, Sascha; Kalke, Jens; Schäfer, Ingo

2018-06-01

Despite of high rates of adverse childhood experiences (ACEs) in pathological gamblers, researchers have rarely studied which types of ACEs often co-occur and how these profiles of ACEs are related to current psychopathology. We aimed to identify profiles of ACEs in pathological gamblers and examined how these profiles were related to gambling-related characteristics and current general psychopathology. In 329 current or lifetime pathological gamblers, diagnosed with the Composite Diagnostic Interview for DSM-IV, 10 types of ACEs were measured using the Adverse Childhood Experiences Questionnaire. Global psychopathology was assessed using the Symptom Checklist SCL-27. ACE profiles were identified using latent class analysis. Differences between ACE profiles in gambling-related characteristics and global psychopathology were analyzed using MANOVA. We found that four out of five gamblers (n=257, 78.1%) reported at least one ACE. Four distinct ACE profiles were identified: 'Low ACE', 'High ACE', 'Physical and emotional abuse', and 'Neglect'. The number of the fulfilled pathological gambling criteria and the severity of current global psychopathology differed between the ACE profiles: Gamblers with a 'High ACE' profile fulfilled more pathological gambling criteria and showed a more severe current psychopathology than gamblers of the 'Low ACE' profile. Gamblers with a 'Physical and emotional abuse' or an 'Emotion neglect' profile showed an intermediate severity of psychopathology. Our findings indicate that four different ACE profiles can be distinguished in pathological gamblers that differed in their gambling-related characteristics and current psychopathology. Systematic assessment of profiles of ACEs in pathological gamblers may inform about the severity of current global psychopathology that might be important to be addressed in addition to gambling-specific treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Real-time feedback control of the plasma density profile on ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Mlynek, A.; Reich, M.; Giannone, L.; Treutterer, W.; Behler, K.; Blank, H.; Buhler, A.; Cole, R.; Eixenberger, H.; Fischer, R.; Lohs, A.; Lüddecke, K.; Merkel, R.; Neu, G.; Ryter, F.; Zasche, D.; ASDEX Upgrade Team

2011-04-01

The spatial distribution of density in a fusion experiment is of significant importance as it enters in numerous analyses and contributes to the fusion performance. The reconstruction of the density profile is therefore commonly done in offline data analysis. In this paper, we present an algorithm which allows for density profile reconstruction from the data of the submillimetre interferometer and the magnetic equilibrium in real-time. We compare the obtained results to the profiles yielded by a numerically more complex offline algorithm. Furthermore, we present recent ASDEX Upgrade experiments in which we used the real-time density profile for active feedback control of the shape of the density profile.

Spectral Line-Shape Model to Replace the Voigt Profile in Spectroscopic Databases

NASA Astrophysics Data System (ADS)

Lisak, Daniel; Ngo, Ngoc Hoa; Tran, Ha; Hartmann, Jean-Michel

2014-06-01

The standard description of molecular line shapes in spectral databases and radiative transfer codes is based on the Voigt profile. It is well known that its simplified assumptions of absorber free motion and independence of collisional parameters from absorber velocity lead to systematic errors in analysis of experimental spectra, and retrieval of gas concentration. We demonstrate1,2 that the partially correlated quadratic speed-dependent hardcollision profile3. (pCqSDHCP) is a good candidate to replace the Voigt profile in the next generations of spectroscopic databases. This profile takes into account the following physical effects: the Doppler broadening, the pressure broadening and shifting of the line, the velocity-changing collisions, the speed-dependence of pressure broadening and shifting, and correlations between velocity- and phase/state-changing collisions. The speed-dependence of pressure broadening and shifting is incorporated into the pCqSDNGP in the so-called quadratic approximation. The velocity-changing collisions lead to the Dicke narrowing effect; however in many cases correlations between velocityand phase/state-changing collisions may lead to effective reduction of observed Dicke narrowing. The hard-collision model of velocity-changing collisions is also known as the Nelkin-Ghatak model or Rautian model. Applicability of the pCqSDHCP for different molecular systems was tested on calculated and experimental spectra of such molecules as H2, O2, CO2, H2O in a wide span of pressures. For all considered systems, pCqSDHCP is able to describe molecular spectra at least an order of magnitude better than the Voigt profile with all fitted parameters being linear with pressure. In the most cases pCqSDHCP can reproduce the reference spectra down to 0.2% or better, which fulfills the requirements of the most demanding remote-sensing applications. An important advantage of pCqSDHCP is that a fast algorithm for its computation was developedab4,5 and allows for its calculation only a few times slower than the standard Voigt profile. Moreover, the pCqSDHCP reduces to many simpler models commonly used in experimental spectra analysis simply by setting some parameters to zero, and it can be easily extended to incorporate the line-mixing effect in the first-order approximation. The idea of using pCqSDHCP as a standard profile to go beyond the Voigt profile for description of H2O line shapes was recently supported by the IUPAC task group6 which also recommended to call this profile with fast computation algorithm the HTP profile (for Hartmann-Tran).

Building CX peanut-shaped disk galaxy profiles. The relative importance of the 3D families of periodic orbits bifurcating at the vertical 2:1 resonance

NASA Astrophysics Data System (ADS)

Patsis, P. A.; Harsoula, M.

2018-05-01

Context. We present and discuss the orbital content of a rather unusual rotating barred galaxy model, in which the three-dimensional (3D) family, bifurcating from x1 at the 2:1 vertical resonance with the known "frown-smile" side-on morphology, is unstable. Aims: Our goal is to study the differences that occur in the phase space structure at the vertical 2:1 resonance region in this case, with respect to the known, well studied, standard case, in which the families with the frown-smile profiles are stable and support an X-shaped morphology. Methods: The potential used in the study originates in a frozen snapshot of an N-body simulation in which a fast bar has evolved. We follow the evolution of the vertical stability of the central family of periodic orbits as a function of the energy (Jacobi constant) and we investigate the phase space content by means of spaces of section. Results: The two bifurcating families at the vertical 2:1 resonance region of the new model change their stability with respect to that of most studied analytic potentials. The structure in the side-on view that is directly supported by the trapping of quasi-periodic orbits around 3D stable periodic orbits has now an infinity symbol (i.e. ∞-type) profile. However, the available sticky orbits can reinforce other types of side-on morphologies as well. Conclusions: In the new model, the dynamical mechanism of trapping quasi-periodic orbits around the 3D stable periodic orbits that build the peanut, supports the ∞-type profile. The same mechanism in the standard case supports the X shape with the frown-smile orbits. Nevertheless, in both cases (i.e. in the new and in the standard model) a combination of 3D quasi-periodic orbits around the stable x1 family with sticky orbits can support a profile reminiscent of the shape of the orbits of the 3D unstable family existing in each model.

Physiology-based face recognition in the thermal infrared spectrum.

PubMed

Buddharaju, Pradeep; Pavlidis, Ioannis T; Tsiamyrtzis, Panagiotis; Bazakos, Mike

2007-04-01

The current dominant approaches to face recognition rely on facial characteristics that are on or over the skin. Some of these characteristics have low permanency can be altered, and their phenomenology varies significantly with environmental factors (e.g., lighting). Many methodologies have been developed to address these problems to various degrees. However, the current framework of face recognition research has a potential weakness due to its very nature. We present a novel framework for face recognition based on physiological information. The motivation behind this effort is to capitalize on the permanency of innate characteristics that are under the skin. To establish feasibility, we propose a specific methodology to capture facial physiological patterns using the bioheat information contained in thermal imagery. First, the algorithm delineates the human face from the background using the Bayesian framework. Then, it localizes the superficial blood vessel network using image morphology. The extracted vascular network produces contour shapes that are characteristic to each individual. The branching points of the skeletonized vascular network are referred to as Thermal Minutia Points (TMPs) and constitute the feature database. To render the method robust to facial pose variations, we collect for each subject to be stored in the database five different pose images (center, midleft profile, left profile, midright profile, and right profile). During the classification stage, the algorithm first estimates the pose of the test image. Then, it matches the local and global TMP structures extracted from the test image with those of the corresponding pose images in the database. We have conducted experiments on a multipose database of thermal facial images collected in our laboratory, as well as on the time-gap database of the University of Notre Dame. The good experimental results show that the proposed methodology has merit, especially with respect to the problem of low permanence over time. More importantly, the results demonstrate the feasibility of the physiological framework in face recognition and open the way for further methodological and experimental research in the area.

Simulation of amide I' band profiles of trans polyproline based on an excitonic coupling model

NASA Astrophysics Data System (ADS)

Measey, Thomas; Schweitzer-Stenner, Reinhard

2005-06-01

We measured the amide I' band profile of the IR, isotropic Raman, anisotropic Raman, and Vibrational Circular Dichroism spectrum of poly- L-proline in D 2O. The band shapes were modeled by using an algorithm that exploits the delocalized character of the excited vibrational states [R. Schweitzer-Stenner, J. Phys. Chem. B. 108 (2004) 16965]. The band shapes could be quantitatively reproduced by invoking the polyproline II or 3 1-helix conformation for all peptide residues. This corroborates the notion that the combined use of the above spectroscopies is an ideal tool to discriminate different conformations associated with the so-called random coil state of peptides.

Profiling of the injected charge drift current transients by cross-sectional scanning technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaubas, E., E-mail: eugenijus.gaubas@ff.vu.lt; Ceponis, T.; Pavlov, J.

2014-02-07

The electric field distribution and charge drift currents in Si particle detectors are analyzed. Profiling of the injected charge drift current transients has been implemented by varying charge injection position within a cross-sectional boundary of the particle detector. The obtained profiles of the induction current density and duration of the injected charge drift pulses fit well the simulated current variations. Induction current transients have been interpreted by different stages of the bipolar and monopolar drift of the injected carriers. Profiles of the injected charge current transients registered in the non-irradiated and neutron irradiated Si diodes are compared. It has beenmore » shown that the mixed regime of the competing processes of drift, recombination, and diffusion appears in the measured current profiles on the irradiated samples. The impact of the avalanche effects can be ignored based on the investigations presented. It has been shown that even a simplified dynamic model enabled us to reproduce the main features of the profiled transients of induced charge drift current.« less

Mapping Bedrock Topography of Taku Glacier with Low Frequency Ground Penetrating RADAR

NASA Astrophysics Data System (ADS)

Westhaver, T.; Towell, A. R.; Lois, A.; Kaluzienski, L. M.; Fredrickson, K.; Riverman, K. L.; Kellerman, B.; Otto, D.; Stewart, A.

2017-12-01

Taku Glacier is the thickest and deepest temperate glacier so far measured in the world. However, the maximum depth has never been determined and the bed is estimated to be at least 600 meters below sea level. Understanding the shape of the bed topography is essential for predicting how the glacier will respond to climate change and how this will affect the future shoreline of Southeast Alaska. We collected both transverse and longitudinal transects of Taku Glacier using ground penetrating radar (GPR) operating at a frequency of 5 MHz, as well as similar profiles from several tributary glaciers including Demorest Glacier, Matthes Glacier and the Northwest Branch of Taku Glacier. We combined previously collected seismic data, digital elevation models (DEMs), and gravimetric data with in situ GPR profiles to produce a bedrock topography model using ArcGIS and Python. Here we present a bedrock topography model of the retreating Taku Glacier that approximates the future shoreline of Southeast Alaska. This modeled shoreline would have profound implications for local community development, ecology and regional hydrology given current climate warming trends.

COMPLEX EVOLUTION OF BILE SALTS IN BIRDS

PubMed Central

Hagey, Lee R.; Vidal, Nicolas; Hofmann, Alan F.; Krasowski, Matthew D.

2010-01-01

Bile salts are the major end-metabolites of cholesterol and are important in lipid digestion and shaping of the gut microflora. There have been limited studies of bile-salt variation in birds. The purpose of our study was to determine bile-salt variation among birds and relate this variation to current avian phylogenies and hypotheses on the evolution of bile salt pathways. We determined the biliary bile-salt composition of 405 phylogenetically diverse bird species, including 7 paleognath species. Bile salt profiles were generally stable within bird families. Complex bile-salt profiles were more common in omnivores and herbivores than in carnivores. The structural variation of bile salts in birds is extensive and comparable to that seen in surveys of bile salts in reptiles and mammals. Birds produce many of the bile salts found throughout nonavian vertebrates and some previously uncharacterized bile salts. One difference between birds and other vertebrates is extensive hydroxylation of carbon-16 of bile salts in bird species. Comparison of our data set of bird bile salts with that of other vertebrates, especially reptiles, allowed us to infer evolutionary changes in the bile salt synthetic pathway. PMID:21113274

Random sampling technique for ultra-fast computations of molecular opacities for exoplanet atmospheres

NASA Astrophysics Data System (ADS)

Min, M.

2017-10-01

Context. Opacities of molecules in exoplanet atmospheres rely on increasingly detailed line-lists for these molecules. The line lists available today contain for many species up to several billions of lines. Computation of the spectral line profile created by pressure and temperature broadening, the Voigt profile, of all of these lines is becoming a computational challenge. Aims: We aim to create a method to compute the Voigt profile in a way that automatically focusses the computation time into the strongest lines, while still maintaining the continuum contribution of the high number of weaker lines. Methods: Here, we outline a statistical line sampling technique that samples the Voigt profile quickly and with high accuracy. The number of samples is adjusted to the strength of the line and the local spectral line density. This automatically provides high accuracy line shapes for strong lines or lines that are spectrally isolated. The line sampling technique automatically preserves the integrated line opacity for all lines, thereby also providing the continuum opacity created by the large number of weak lines at very low computational cost. Results: The line sampling technique is tested for accuracy when computing line spectra and correlated-k tables. Extremely fast computations ( 3.5 × 105 lines per second per core on a standard current day desktop computer) with high accuracy (≤1% almost everywhere) are obtained. A detailed recipe on how to perform the computations is given.

Design of an electromagnetic accelerator for turbulent hydrodynamic mix studies

NASA Astrophysics Data System (ADS)

Susoeff, A. R.; Hawke, R. S.; Morrison, J. J.; Dimonte, G.; Remington, B. A.

1993-12-01

An electromagnetic accelerator in the form of a linear electric motor (LEM) has been designed to achieve controlled acceleration profiles of a carriage containing hydrodynamically unstable fluids for the investigation of the development of turbulent mix. The Rayleigh-Taylor instability is investigated by accelerating two dissimilar density fluids using the LEM to achieve a wide variety of acceleration and deceleration profiles. The acceleration profiles are achieved by independent control of rail and augmentation currents. A variety of acceleration-time profiles are possible including: (1) constant, (2) impulsive and (3) shaped. The LEM and support structure are a robust design in order to withstand high loads with deflections and to mitigate operational vibration. Vibration of the carriage during acceleration could create artifacts in the data which would interfere with the intended study of the Rayleigh-Taylor instability. The design allows clear access for diagnostic techniques such as laser induced fluorescence radiography, shadowgraphs and particle imaging velocimetry. Electromagnetic modeling codes were used to optimize the rail and augmentation coil positions within the support structure framework. Results of contemporary studies for non-arcing sliding contact of solid armatures are used for the design of the driving armature and the dynamic electromagnetic braking system. A 0.6MJ electrolytic capacitor bank is used for energy storage to drive the LEM. This report will discuss a LEM design which will accelerate masses of up to 3kg to a maximum of about 3000g(sub o), where g(sub o) is accelerated due to gravity.

A tripolar current-steering stimulator ASIC for field shaping in deep brain stimulation.

PubMed

Valente, Virgilio; Demosthenous, Andreas; Bayford, Richard

2012-06-01

A significant problem with clinical deep brain stimulation (DBS) is the high variability of its efficacy and the frequency of side effects, related to the spreading of current beyond the anatomical target area. This is the result of the lack of control that current DBS systems offer on the shaping of the electric potential distribution around the electrode. This paper presents a stimulator ASIC with a tripolar current-steering output stage, aiming at achieving more selectivity and field shaping than current DBS systems. The ASIC was fabricated in a 0.35-μ m CMOS technology occupying a core area of 0.71 mm(2). It consists of three current sourcing/sinking channels. It is capable of generating square and exponential-decay biphasic current pulses with five different time constants up to 28 ms and delivering up to 1.85 mA of cathodic current, in steps of 4 μA, from a 12 V power supply. Field shaping was validated by mapping the potential distribution when injecting current pulses through a multicontact DBS electrode in saline.

A Total Ozone Dependent Ozone Profile Climatology Based on Ozone-Sondes and Aura MLS Data

NASA Astrophysics Data System (ADS)

Labow, G. J.; McPeters, R. D.; Ziemke, J. R.

2014-12-01

A new total ozone-based ozone profile climatology has been created for use in satellite and/or ground based ozone retrievals. This climatology was formed by combining data from the Microwave Limb Sounder (MLS) with data from balloon sondes and binned by zone and total ozone. Because profile shape varies with total column ozone, this climatology better captures the ozone variations than the previously used seasonal climatologies, especially near the tropopause. This is significantly different than ozone climatologies used in the past as there is no time component. The MLS instrument on Aura has excellent latitude coverage and measures ozone profiles daily from the upper troposphere to the lower mesosphere at ~3.5 km resolution. Almost a million individual MLS ozone measurements are merged with data from over 55,000 ozonesondes which are then binned as a function of total ozone. The climatology consists of average ozone profiles as a function of total ozone for six 30 degree latitude bands covering altitudes from 0-75 km (in Z* pressure altitude coordinates). This new climatology better represents the profile shape as a function of total ozone than previous climatologies and shows some remarkable and somewhat unexpected correlations between total ozone and ozone in the lower altitudes, particularly in the lower and middle troposphere. These data can also be used to infer biases and errors in either the MLS retrievals or ozone sondes.

Free-energy landscape of ion-channel voltage-sensor–domain activation

PubMed Central

Delemotte, Lucie; Kasimova, Marina A.; Klein, Michael L.; Tarek, Mounir; Carnevale, Vincenzo

2015-01-01

Voltage sensor domains (VSDs) are membrane-bound protein modules that confer voltage sensitivity to membrane proteins. VSDs sense changes in the transmembrane voltage and convert the electrical signal into a conformational change called activation. Activation involves a reorganization of the membrane protein charges that is detected experimentally as transient currents. These so-called gating currents have been investigated extensively within the theoretical framework of so-called discrete-state Markov models (DMMs), whereby activation is conceptualized as a series of transitions across a discrete set of states. Historically, the interpretation of DMM transition rates in terms of transition state theory has been instrumental in shaping our view of the activation process, whose free-energy profile is currently envisioned as composed of a few local minima separated by steep barriers. Here we use atomistic level modeling and well-tempered metadynamics to calculate the configurational free energy along a single transition from first principles. We show that this transition is intrinsically multidimensional and described by a rough free-energy landscape. Remarkably, a coarse-grained description of the system, based on the use of the gating charge as reaction coordinate, reveals a smooth profile with a single barrier, consistent with phenomenological models. Our results bridge the gap between microscopic and macroscopic descriptions of activation dynamics and show that choosing the gating charge as reaction coordinate masks the topological complexity of the network of microstates participating in the transition. Importantly, full characterization of the latter is a prerequisite to rationalize modulation of this process by lipids, toxins, drugs, and genetic mutations. PMID:25535341

Free-energy landscape of ion-channel voltage-sensor-domain activation.

PubMed

Delemotte, Lucie; Kasimova, Marina A; Klein, Michael L; Tarek, Mounir; Carnevale, Vincenzo

2015-01-06

Voltage sensor domains (VSDs) are membrane-bound protein modules that confer voltage sensitivity to membrane proteins. VSDs sense changes in the transmembrane voltage and convert the electrical signal into a conformational change called activation. Activation involves a reorganization of the membrane protein charges that is detected experimentally as transient currents. These so-called gating currents have been investigated extensively within the theoretical framework of so-called discrete-state Markov models (DMMs), whereby activation is conceptualized as a series of transitions across a discrete set of states. Historically, the interpretation of DMM transition rates in terms of transition state theory has been instrumental in shaping our view of the activation process, whose free-energy profile is currently envisioned as composed of a few local minima separated by steep barriers. Here we use atomistic level modeling and well-tempered metadynamics to calculate the configurational free energy along a single transition from first principles. We show that this transition is intrinsically multidimensional and described by a rough free-energy landscape. Remarkably, a coarse-grained description of the system, based on the use of the gating charge as reaction coordinate, reveals a smooth profile with a single barrier, consistent with phenomenological models. Our results bridge the gap between microscopic and macroscopic descriptions of activation dynamics and show that choosing the gating charge as reaction coordinate masks the topological complexity of the network of microstates participating in the transition. Importantly, full characterization of the latter is a prerequisite to rationalize modulation of this process by lipids, toxins, drugs, and genetic mutations.

Field induced transient current in one-dimensional nanostructure

NASA Astrophysics Data System (ADS)

Sako, Tokuei; Ishida, Hiroshi

2018-07-01

Field-induced transient current in one-dimensional nanostructures has been studied by a model of an electron confined in a 1D attractive Gaussian potential subjected both to electrodes at the terminals and to an ultrashort pulsed oscillatory electric field with the central frequency ω and the FWHM pulse width Γ. The time-propagation of the electron wave packet has been simulated by integrating the time-dependent Schrödinger equation directly relying on the second-order symplectic integrator method. The transient current has been calculated as the flux of the probability density of the escaping wave packet emitted from the downstream side of the confining potential. When a static bias-field E0 is suddenly applied, the resultant transient current shows an oscillatory decay behavior with time followed by a minimum structure before converging to a nearly constant value. The ω-dependence of the integrated transient current induced by the pulsed electric field has shown an asymmetric resonance line-shape for large Γ while it shows a fringe pattern on the spectral line profile for small Γ. These observations have been rationalized on the basis of the energy-level structure and lifetime of the quasibound states in the bias-field modified confining potential obtained by the complex-scaling Fourier grid Hamiltonian method.

A magnetospheric magnetic field model with flexible current systems driven by independent physical parameters

NASA Technical Reports Server (NTRS)

Hilmer, Robert V.; Voigt, Gerd-Hannes

1995-01-01

A tilt-dependent magnetic field model of the Earth's magnetosphere with variable magnetopause standoff distance is presented. Flexible analytic representations for the ring and cross-tail currents, each composed of the elements derived from the Tsyganenko and Usmanov (1982) model, are combined with the fully shielded vacuum dipole configurations of Voigt (1981). Although the current sheet does not warp in the y-z plane, changes in the shape and position of the neutral sheet with dipole tilt are consistent with both MHD equilibrium theory and observations. In addition, there is good agreement with observed Delta B profiles and the average equatorial contours of magnetic field magnitude. While the dipole field is rigorously shielded within the defined magnetopause, the ring and cross-tails currents are not similarly confined, consequently, the model's region of validity is limited to the inner magnetosphere. The model depends on four independent external parameters. We present a simple but limited method of simulating several substorm related magnetic field changes associated with the disrupion of the near-Earth cross-tail current sheet and collapse of the midnight magnetotail field region. This feature further facilitates the generation of magnetic field configuration time sequences useful in plasma convection simulations of real magnetospheric events.

Input-current shaped ac to dc converters

NASA Technical Reports Server (NTRS)

1986-01-01

The problem of achieving near unity power factor while supplying power to a dc load from a single phase ac source of power is examined. Power processors for this application must perform three functions: input current shaping, energy storage, and output voltage regulation. The methods available for performing each of these three functions are reviewed. Input current shaping methods are either active or passive, with the active methods divided into buck-like and boost-like techniques. In addition to large reactances, energy storage methods include resonant filters, active filters, and active storage schemes. Fast voltage regulation can be achieved by post regulation or by supplementing the current shaping topology with an extra switch. Some indications of which methods are best suited for particular applications concludes the discussion.

Structural imprints in vivo decode RNA regulatory mechanisms

PubMed Central

Spitale, Robert C.; Flynn, Ryan A.; Zhang, Qiangfeng Cliff; Crisalli, Pete; Lee, Byron; Jung, Jong-Wha; Kuchelmeister, Hannes Y.; Batista, Pedro J.; Torre, Eduardo A.; Kool, Eric T.; Chang, Howard Y.

2015-01-01

Visualizing the physical basis for molecular behavior inside living cells is a grand challenge in biology. RNAs are central to biological regulation, and RNA’s ability to adopt specific structures intimately controls every step of the gene expression program1. However, our understanding of physiological RNA structures is limited; current in vivo RNA structure profiles view only two of four nucleotides that make up RNA2,3. Here we present a novel biochemical approach, In Vivo Click SHAPE (icSHAPE), that enables the first global view of RNA secondary structures of all four bases in living cells. icSHAPE of mouse embryonic stem cell transcriptome versus purified RNA folded in vitro shows that the structural dynamics of RNA in the cellular environment distinguishes different classes of RNAs and regulatory elements. Structural signatures at translational start sites and ribosome pause sites are conserved from in vitro, suggesting that these RNA elements are programmed by sequence. In contrast, focal structural rearrangements in vivo reveal precise interfaces of RNA with RNA binding proteins or RNA modification sites that are consistent with atomic-resolution structural data. Such dynamic structural footprints enable accurate prediction of RNA-protein interactions and N6-methyladenosine (m6A) modification genome-wide. These results open the door for structural genomics of RNA in living cells and reveal key physiological structures controlling gene expression. PMID:25799993

Backward-gazing method for heliostats shape errors measurement and calibration

NASA Astrophysics Data System (ADS)

Coquand, Mathieu; Caliot, Cyril; Hénault, François

2017-06-01

The pointing and canting accuracies and the surface shape of the heliostats have a great influence on the solar tower power plant efficiency. At the industrial scale, one of the issues to solve is the time and the efforts devoted to adjust the different mirrors of the faceted heliostats, which could take several months if the current methods were used. Accurate control of heliostat tracking requires complicated and onerous devices. Thus, methods used to adjust quickly the whole field of a plant are essential for the rise of solar tower technology with a huge number of heliostats. Wavefront detection is widely use in adaptive optics and shape error reconstruction. Such systems can be sources of inspiration for the measurement of solar facets misalignment and tracking errors. We propose a new method of heliostat characterization inspired by adaptive optics devices. This method aims at observing the brightness distributions on heliostat's surface, from different points of view close to the receiver of the power plant, in order to calculate the wavefront of the reflection of the sun on the concentrated surface to determine its errors. The originality of this new method is to use the profile of the sun to determine the defects of the mirrors. In addition, this method would be easy to set-up and could be implemented without sophisticated apparatus: only four cameras would be used to perform the acquisitions.

Technology optimization techniques for multicomponent optical band-pass filter manufacturing

NASA Astrophysics Data System (ADS)

Baranov, Yuri P.; Gryaznov, Georgiy M.; Rodionov, Andrey Y.; Obrezkov, Andrey V.; Medvedev, Roman V.; Chivanov, Alexey N.

2016-04-01

Narrowband optical devices (like IR-sensing devices, celestial navigation systems, solar-blind UV-systems and many others) are one of the most fast-growing areas in optical manufacturing. However, signal strength in this type of applications is quite low and performance of devices depends on attenuation level of wavelengths out of operating range. Modern detectors (photodiodes, matrix detectors, photomultiplier tubes and others) usually do not have required selectivity or have higher sensitivity to background spectrum at worst. Manufacturing of a single component band-pass filter with high attenuation level of wavelength is resource-intensive task. Sometimes it's not possible to find solution for this problem using existing technologies. Different types of filters have technology variations of transmittance profile shape due to various production factors. At the same time there are multiple tasks with strict requirements for background spectrum attenuation in narrowband optical devices. For example, in solar-blind UV-system wavelengths above 290-300 nm must be attenuated by 180dB. In this paper techniques of multi-component optical band-pass filters assembly from multiple single elements with technology variations of transmittance profile shape for optimal signal-tonoise ratio (SNR) were proposed. Relationships between signal-to-noise ratio and different characteristics of transmittance profile shape were shown. Obtained practical results were in rather good agreement with our calculations.

Note: A contraction channel design for planar shock wave enhancement

NASA Astrophysics Data System (ADS)

Zhan, Dongwen; Li, Zhufei; Yang, Jianting; Zhu, Yujian; Yang, Jiming

2018-05-01

A two-dimensional contraction channel with a theoretically designed concave-oblique-convex wall profile is proposed to obtain a smooth planar-to-planar shock transition with shock intensity amplification that can easily overcome the limitations of a conventional shock tube. The concave segment of the wall profile, which is carefully determined based on shock dynamics theory, transforms the shock shape from an initial plane into a cylindrical arc. Then the level of shock enhancement is mainly contributed by the cylindrical shock convergence within the following oblique segment, after which the cylindrical shock is again "bent" back into a planar shape through the third section of the shock dynamically designed convex segment. A typical example is presented with a combination of experimental and numerical methods, where the shape of transmitted shock is almost planar and the post-shock flow has no obvious reflected waves. A quantitative investigation shows that the difference between the designed and experimental transmitted shock intensities is merely 1.4%. Thanks to its advantage that the wall profile design is insensitive to initial shock strength variations and high-temperature gas effects, this method exhibits attractive potential as an efficient approach to a certain, controllable, extreme condition of a strong shock wave with relatively uniform flow behind.

Model-based segmentation of abdominal aortic aneurysms in CTA images

NASA Astrophysics Data System (ADS)

de Bruijne, Marleen; van Ginneken, Bram; Niessen, Wiro J.; Loog, Marco; Viergever, Max A.

2003-05-01

Segmentation of thrombus in abdominal aortic aneurysms is complicated by regions of low boundary contrast and by the presence of many neighboring structures in close proximity to the aneurysm wall. We present an automated method that is similar to the well known Active Shape Models (ASM), combining a three-dimensional shape model with a one-dimensional boundary appearance model. Our contribution is twofold: we developed a non-parametric appearance modeling scheme that effectively deals with a highly varying background, and we propose a way of generalizing models of curvilinear structures from small training sets. In contrast with the conventional ASM approach, the new appearance model trains on both true and false examples of boundary profiles. The probability that a given image profile belongs to the boundary is obtained using k nearest neighbor (kNN) probability density estimation. The performance of this scheme is compared to that of original ASMs, which minimize the Mahalanobis distance to the average true profile in the training set. The generalizability of the shape model is improved by modeling the objects axis deformation independent of its cross-sectional deformation. A leave-one-out experiment was performed on 23 datasets. Segmentation using the kNN appearance model significantly outperformed the original ASM scheme; average volume errors were 5.9% and 46% respectively.

Trends in stratospheric ozone profiles using functional mixed models

NASA Astrophysics Data System (ADS)

Park, A.; Guillas, S.; Petropavlovskikh, I.

2013-11-01

This paper is devoted to the modeling of altitude-dependent patterns of ozone variations over time. Umkehr ozone profiles (quarter of Umkehr layer) from 1978 to 2011 are investigated at two locations: Boulder (USA) and Arosa (Switzerland). The study consists of two statistical stages. First we approximate ozone profiles employing an appropriate basis. To capture primary modes of ozone variations without losing essential information, a functional principal component analysis is performed. It penalizes roughness of the function and smooths excessive variations in the shape of the ozone profiles. As a result, data-driven basis functions (empirical basis functions) are obtained. The coefficients (principal component scores) corresponding to the empirical basis functions represent dominant temporal evolution in the shape of ozone profiles. We use those time series coefficients in the second statistical step to reveal the important sources of the patterns and variations in the profiles. We estimate the effects of covariates - month, year (trend), quasi-biennial oscillation, the solar cycle, the Arctic oscillation, the El Niño/Southern Oscillation cycle and the Eliassen-Palm flux - on the principal component scores of ozone profiles using additive mixed effects models. The effects are represented as smooth functions and the smooth functions are estimated by penalized regression splines. We also impose a heteroscedastic error structure that reflects the observed seasonality in the errors. The more complex error structure enables us to provide more accurate estimates of influences and trends, together with enhanced uncertainty quantification. Also, we are able to capture fine variations in the time evolution of the profiles, such as the semi-annual oscillation. We conclude by showing the trends by altitude over Boulder and Arosa, as well as for total column ozone. There are great variations in the trends across altitudes, which highlights the benefits of modeling ozone profiles.

Development of a new virtual diagnostic for V3FIT

NASA Astrophysics Data System (ADS)

Trevisan, G. L.; Cianciosa, M. R.; Terranova, D.; Hanson, J. D.

2014-12-01

The determination of plasma equilibria from diagnostic information is a fundamental issue. V3FIT is a fully three-dimensional reconstruction code capable of solving the inverse problem using both magnetic and kinetic measurements. It uses VMEC as core equilibrium solver and supports both free- and fixed-boundary reconstruction approaches. In fixed-boundary mode VMEC does not use explicit information about currents in external coils, even though it has important effects on the shape of the safety factor profile. Indeed, the edge safety factor influences the reversal position in RFP plasmas, which then determines the position of the m = 0 island chain and the edge transport properties. In order to exploit such information a new virtual diagnostic has been developed, that thanks to Ampère's law relates the external current through the center of the torus to the circulation of the toroidal magnetic field on the outermost flux surface. The reconstructions that exploit the new diagnostic are indeed found to better interpret the experimental data with respect to edge physics.

Electrophoretic deposition (EPD): Mechanisms, kinetics, and application to ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, P.; Nicholson, P.S.

1996-08-01

The mechanisms of electrophoretic deposition (EPD) are discussed and their shortcomings identified. The kinetics of the processes involved are analyzed for constant-current and constant-voltage conditions. A method of determining the Hamaker constant of suspended particles is developed by modeling the relationship between the particle interaction energy and the suspension stability. A three-probe dc technique is used to map the voltage profile around the depositing electrode, and the results are used to explain discrepancies between the calculated and experimentally observed voltage drops during deposition. A mechanism of deposition is proposed based on DLVO theory and particle double-layer distortion/thinning on application ofmore » a dc field to the suspension. Kinetic equations are developed for constant-current and constant-voltage EPD using mass balance conditions; these are verified by experiments. After the phenomenon is introduced and discussed, a critique of the application of EPD to the synthesis of ceramic shapes and coatings is given.« less

Predicting kinetic nanocrystal shapes through multi-scale theory and simulation: Polyvinylpyrrolidone-mediated growth of Ag nanocrystals

NASA Astrophysics Data System (ADS)

Balankura, Tonnam; Qi, Xin; Zhou, Ya; Fichthorn, Kristen A.

2016-10-01

In the shape-controlled synthesis of colloidal Ag nanocrystals, structure-directing agents, particularly polyvinylpyrrolidone (PVP), are known to be a key additive in making nanostructures with well-defined shapes. Although many Ag nanocrystals have been successfully synthesized using PVP, the mechanism by which PVP actuates shape control remains elusive. Here, we present a multi-scale theoretical framework for kinetic Wulff shape predictions that accounts for the chemical environment, which we used to probe the kinetic influence of the adsorbed PVP film. Within this framework, we use umbrella-sampling molecular dynamics simulations to calculate the potential of mean force and diffusion coefficient profiles of Ag atom deposition onto Ag(100) and Ag(111) in ethylene glycol solution with surface-adsorbed PVP. We use these profiles to calculate the mean-first passage times and implement extensive Brownian dynamics simulations, which allows the kinetic effects to be quantitatively evaluated. Our results show that PVP films can regulate the flux of Ag atoms to be greater towards Ag(111) than Ag(100). PVP's preferential binding towards Ag(100) over Ag(111) gives PVP its flux-regulating capabilities through the lower free-energy barrier of Ag atoms to cross the lower-density PVP film on Ag(111) and enhanced Ag trapping by the extended PVP film on Ag(111). Under kinetic control, {100}-faceted nanocrystals will be formed when the Ag flux is greater towards Ag(111). The predicted kinetic Wulff shapes are in agreement with the analogous experimental system.

Beam shaping as an enabler for new applications

NASA Astrophysics Data System (ADS)

Guertler, Yvonne; Kahmann, Max; Havrilla, David

2017-02-01

For many years, laser beam shaping has enabled users to achieve optimized process results as well as manage challenging applications. The latest advancements in industrial lasers and processing optics have taken this a step further as users are able to adapt the beam shape to meet specific application requirements in a very flexible way. TRUMPF has developed a wide range of experience in creating beam profiles at the work piece for optimized material processing. This technology is based on the physical model of wave optics and can be used with ultra short pulse lasers as well as multi-kW cw lasers. Basically, the beam shape can be adapted in all three dimensions in space, which allows maximum flexibility. Besides adaption of intensity profile, even multi-spot geometries can be produced. This approach is very cost efficient, because a standard laser source and (in the case of cw lasers) a standard fiber can be used without any special modifications. Based on this innovative beam shaping technology, TRUMPF has developed new and optimized processes. Two of the most recent application developments using these techniques are cutting glass and synthetic sapphire with ultra-short pulse lasers and enhanced brazing of hot dip zinc coated steel for automotive applications. Both developments lead to more efficient and flexible production processes, enabled by laser technology and open the door to new opportunities. They also indicate the potential of beam shaping techniques since they can be applied to both single-mode laser sources (TOP Cleave) and multi-mode laser sources (brazing).

RF current profile control studies in the alcator C-mod tokamak

NASA Astrophysics Data System (ADS)

Bonoli, P. T.; Porkolab, M.; Wukitch, S. J.; Bernabei, S.; Kaita, R.; Mikkelsen, D.; Phillips, C. K.; Schilling, G.

1999-09-01

Time dependent calculations of lower hybrid (LH) current profile control in Alcator C-Mod have been done using the TRANSP [1], FPPRF [2], and LSC [3] codes. Up to 3 MW of LH current drive power was applied in plasmas with high power ICRF minority heating (PICH=1.8-3 MW) and fast current ramp up. Using the experimentally measured temperature profiles, off-axis current generation resulted in nonmonotonic q-profiles with qmin~=1.6. Self-consistent effects of off-axis electron heating by the LH power were also included in the analysis and significant broadening of the electron temperature profile was found with qmin>~2 and a larger shear reversal radius.

The Wonder Years: A Profile of Madhav Chavan

ERIC Educational Resources Information Center

Mukerji, Shalini

2017-01-01

An idea took shape in the slums of Mumbai in the early nineties and went on to become a peoples' movement to address the problem of providing quality education for all of India's children. This piece profiles Dr. Madhav Chavan, the man who provided the dynamic vision for and creative leadership of that mission/movement. Dr. Chavan combined the…

Fundamental Parameters Line Profile Fitting in Laboratory Diffractometers

PubMed Central

Cheary, R. W.; Coelho, A. A.; Cline, J. P.

2004-01-01

The fundamental parameters approach to line profile fitting uses physically based models to generate the line profile shapes. Fundamental parameters profile fitting (FPPF) has been used to synthesize and fit data from both parallel beam and divergent beam diffractometers. The refined parameters are determined by the diffractometer configuration. In a divergent beam diffractometer these include the angular aperture of the divergence slit, the width and axial length of the receiving slit, the angular apertures of the axial Soller slits, the length and projected width of the x-ray source, the absorption coefficient and axial length of the sample. In a parallel beam system the principal parameters are the angular aperture of the equatorial analyser/Soller slits and the angular apertures of the axial Soller slits. The presence of a monochromator in the beam path is normally accommodated by modifying the wavelength spectrum and/or by changing one or more of the axial divergence parameters. Flat analyzer crystals have been incorporated into FPPF as a Lorentzian shaped angular acceptance function. One of the intrinsic benefits of the fundamental parameters approach is its adaptability any laboratory diffractometer. Good fits can normally be obtained over the whole 20 range without refinement using the known properties of the diffractometer, such as the slit sizes and diffractometer radius, and emission profile. PMID:27366594

Eddy-Current Inspection Of Graphite-Fiber Composites

NASA Technical Reports Server (NTRS)

Workman, G. L.; Bryson, C. C.

1993-01-01

NASA technical memorandum describes initial research on, and proposed development of, automated system for nondestructive eddy-current inspection of parts made of graphite-fiber/epoxy-matrix composite materials. Sensors in system E-shaped or U-shaped eddy-current probes like those described in "Eddy-Current Probes For Inspecting Graphite-Fiber Composites" (MFS-26129).

Onto the stability analysis of hyperbolic secant-shaped Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Sabari, S.; Murali, R.

2018-05-01

We analyze the stability of the hyperbolic secant-shaped attractive Bose-Einstein condensate in the absence of external trapping potential. The appropriate theoretical model for the system is described by the nonlinear mean-field Gross-Pitaevskii equation with time varying two-body interaction effects. Using the variational method, the stability of the system is analyzed under the influence of time varying two-body interactions. Further we confirm that the stability of the attractive condensate increases by considering the hyperbolic secant-shape profile instead of Gaussian shape. The analytical results are compared with the numerical simulation by employing the split-step Crank-Nicholson method.

Design Models for Shaping of a Tooth Profile of External Fine-Module Ratchet Teeth

NASA Astrophysics Data System (ADS)

Sharkov, O. V.; Koryagin, S. I.; Velikanov, N. L.

2016-04-01

Simulation of the shaping for the fine-module external ratchet teeth at which the contacting surfaces are formed by the straight segments is considered in this paper. The design schemes for shaping of the proposed ratchet teeth by a shaper cutter and a rack are obtained. It is defined that the maximum length of the straight segment of the front edge ratchet teeth will be formed at shaping by a rack cutter. The effect of a module, a gradient angle and a radius of blank circles on the length of the straight segment of the front edge ratchet teeth is investigated.

Acoustic contrast control in an arc-shaped area using a linear loudspeaker array.

PubMed

Zhao, Sipei; Qiu, Xiaojun; Burnett, Ian

2015-02-01

This paper proposes a method of creating acoustic contrast control in an arc-shaped area using a linear loudspeaker array. The boundary of the arc-shaped area is treated as the envelope of the tangent lines that can be formed by manipulating the phase profile of the loudspeakers in the array. When compared with the existing acoustic contrast control method, the proposed method is able to generate sound field inside an arc-shaped area and achieve a trade-off between acoustic uniformity and acoustic contrast. The acoustic contrast created by the proposed method increases while the acoustic uniformity decreases with frequency.

A Three-Dimensional Coupled Internal/External Simulation of a Film-Cooled Turbine Vane

NASA Technical Reports Server (NTRS)

Heidmann, James D.; Rigby, David L.; Ameri, Ali A.

1999-01-01

A three-dimensional Navier-Stokes simulation has been performed for a realistic film-cooled turbine vane using the LeRC-HT code. The simulation includes the flow regions inside the coolant plena and film cooling holes in addition to the external flow. The vane is the subject of an upcoming NASA Glenn Research Center experiment and has both circular cross-section and shaped film cooling holes. This complex geometry is modeled using a multi-block grid which accurately discretizes the actual vane geometry including shaped holes. The simulation matches operating conditions for the planned experiment and assumes periodicity in the spanwise direction on the scale of one pitch of the film cooling hole pattern. Two computations were performed for different isothermal wall temperatures, allowing independent determination of heat transfer coefficients and film effectiveness values. The results indicate separate localized regions of high heat transfer coefficient values, while the shaped holes provide a reduction in heat flux through both parameters. Hole exit data indicate rather simple skewed profiles for the round holes, but complex profiles for the shaped holes with mass fluxes skewed strongly toward their leading edges.

Improving satellite retrievals of NO2 in biomass burning regions

NASA Astrophysics Data System (ADS)

Bousserez, N.; Martin, R. V.; Lamsal, L. N.; Mao, J.; Cohen, R. C.; Anderson, B. E.

2010-12-01

The quality of space-based nitrogen dioxide (NO2) retrievals from solar backscatter depends on a priori knowledge of the NO2 profile shape as well as the effects of atmospheric scattering. These effects are characterized by the air mass factor (AMF) calculation. Calculation of the AMF combines a radiative transfer calculation together with a priori information about aerosols and about NO2 profiles (shape factors), which are usually taken from a chemical transport model. In this work we assess the impact of biomass burning emissions on the AMF using the LIDORT radiative transfer model and a GEOS-Chem simulation based on a daily fire emissions inventory (FLAMBE). We evaluate the GEOS-Chem aerosol optical properties and NO2 shape factors using in situ data from the ARCTAS summer 2008 (North America) and DABEX winter 2006 (western Africa) experiments. Sensitivity studies are conducted to assess the impact of biomass burning on the aerosols and the NO2 shape factors used in the AMF calculation. The mean aerosol correction over boreal fires is negligible (+3%), in contrast with a large reduction (-18%) over African savanna fires. The change in sign and magnitude over boreal forest and savanna fires appears to be driven by the shielding effects that arise from the greater biomass burning aerosol optical thickness (AOT) above the African biomass burning NO2. In agreement with previous work, the single scattering albedo (SSA) also affects the aerosol correction. We further investigated the effect of clouds on the aerosol correction. For a fixed AOT, the aerosol correction can increase from 20% to 50% when cloud fraction increases from 0 to 30%. Over both boreal and savanna fires, the greatest impact on the AMF is from the fire-induced change in the NO2 profile (shape factor correction), that decreases the AMF by 38% over the boreal fires and by 62% of the savanna fires. Combining the aerosol and shape factor corrections together results in small differences compared to the shape factor correction alone (without the aerosol correction), indicating that a shape factor-only correction is a good approximation of the total AMF correction associated with fire emissions. We use this result to define a measurement-based correction of the AMF based on the relationship between the slant column variability and the variability of the shape factor in the lower troposphere. This method may be generalized to other types of emission sources.

Age-dependent Fourier model of the shape of the isolated ex vivo human crystalline lens.

PubMed

Urs, Raksha; Ho, Arthur; Manns, Fabrice; Parel, Jean-Marie

2010-06-01

To develop an age-dependent mathematical model of the zero-order shape of the isolated ex vivo human crystalline lens, using one mathematical function, that can be subsequently used to facilitate the development of other models for specific purposes such as optical modeling and analytical and numerical modeling of the lens. Profiles of whole isolated human lenses (n=30) aged 20-69, were measured from shadow-photogrammetric images. The profiles were fit to a 10th-order Fourier series consisting of cosine functions in polar-co-ordinate system that included terms for tilt and decentration. The profiles were corrected using these terms and processed in two ways. In the first, each lens was fit to a 10th-order Fourier series to obtain thickness and diameter, while in the second, all lenses were simultaneously fit to a Fourier series equation that explicitly include linear terms for age to develop an age-dependent mathematical model for the whole lens shape. Thickness and diameter obtained from Fourier series fits exhibited high correlation with manual measurements made from shadow-photogrammetric images. The root-mean-squared-error of the age-dependent fit was 205 microm. The age-dependent equations provide a reliable lens model for ages 20-60 years. The contour of the whole human crystalline lens can be modeled with a Fourier series. Shape obtained from the age-dependent model described in this paper can be used to facilitate the development of other models for specific purposes such as optical modeling and analytical and numerical modeling of the lens. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Slope gradient and shape effects on soil profiles in the northern mountainous forests of Iran

NASA Astrophysics Data System (ADS)

Fazlollahi Mohammadi, M.; Jalali, S. G. H.; Kooch, Y.; Said-Pullicino, D.

2016-12-01

In order to evaluate the variability of the soil profiles at two shapes (concave and convex) and five positions (summit, shoulder, back slope, footslope and toeslope) of a slope, a study of a virgin area was made in a Beech stand of mountain forests, northern Iran. Across the slope positions, the soil profiles demonstrated significant changes due to topography for two shape slopes. The solum depth of the convex slope was higher than the concave one in all five positions, and it decreased from the summit to shoulder and increased from the mid to lower slope positions for both convex and concave slopes. The thin solum at the upper positions and concave slope demonstrated that pedogenetic development is least at upper slope positions and concave slope where leaching and biomass productivity are less than at lower slopes and concave slope. A large decrease in the thickness of O and A horizons from the summit to back slope was noted for both concave and convex slopes, but it increased from back slope toward down slope for both of them. The average thickness of B horizons increased from summit to down slopes in the case of the concave slope, but in the case of convex slope it decreased from summit to shoulder and afterwards it increased to the down slope. The thicknesses of the different horizons varied in part in the different positions and shape slopes because they had different plant species cover and soil features, which were related to topography.

Voids in cosmological simulations over cosmic time

NASA Astrophysics Data System (ADS)

Wojtak, Radosław; Powell, Devon; Abel, Tom

2016-06-01

We study evolution of voids in cosmological simulations using a new method for tracing voids over cosmic time. The method is based on tracking watershed basins (contiguous regions around density minima) of well-developed voids at low redshift, on a regular grid of density field. It enables us to construct a robust and continuous mapping between voids at different redshifts, from initial conditions to the present time. We discuss how the new approach eliminates strong spurious effects of numerical origin when voids' evolution is traced by matching voids between successive snapshots (by analogy to halo merger trees). We apply the new method to a cosmological simulation of a standard Λ-cold-dark-matter cosmological model and study evolution of basic properties of typical voids (with effective radii 6 h-1 Mpc < Rv < 20 h-1 Mpc at redshift z = 0) such as volumes, shapes, matter density distributions and relative alignments. The final voids at low redshifts appear to retain a significant part of the configuration acquired in initial conditions. Shapes of voids evolve in a collective way which barely modifies the overall distribution of the axial ratios. The evolution appears to have a weak impact on mutual alignments of voids implying that the present state is in large part set up by the primordial density field. We present evolution of dark matter density profiles computed on isodensity surfaces which comply with the actual shapes of voids. Unlike spherical density profiles, this approach enables us to demonstrate development of theoretically predicted bucket-like shape of the final density profiles indicating a wide flat core and a sharp transition to high-density void walls.

Shape, zonal winds and gravitational field of Jupiter: a fully self-consistent, multi-layered model

NASA Astrophysics Data System (ADS)

Schubert, Gerald; Kong, Dali; Zhang, Keke

2016-10-01

We construct a three-dimensional, finite-element, fully self-consistent, multi-layered,non-spheroidal model of Jupiter consisting of an inner core, a metallic electrically conducting dynamo region and an outer molecular electrically insulating envelope. We assume that the Jovian zonal winds are on cylinders parallel to the rotation axis but, due to the effect of magnetic braking, are confined within the outer molecular envelope. Two related calculations are carried out. The first provides an accurate description of the shape and internal density profile of Jupiter; the effect of rotational distortion is not treated as a small perturbation on a spherically symmetric state. This calculation determines the density, size and shape of the inner core, the irregular shape of the 1-bar pressure level, and the internal structure of Jupiter; the full effect of rotational distortion, without the influence of the zonal winds, is accounted for. Our multi-layered model is able to produce the known mass, the known equatorial and polar radii, and the known zonal gravitational coefficient J2 of Jupiter within their error bars; it also yields the coefficients J4 and J6 within about 5% accuracy, and the core equatorial radius 0.09RJ containing 3.73 Earth masses.The second calculation determines the variation of the gravitational field caused solely by the effect of the zonal winds on the rotationally distorted non-spheroidal Jupiter. Four different cases, ranging from a deep wind profile to a very shallow profile, are considered and implications for accurate interpretation of the zonal gravitational coefficients expected from the Juno mission are discussed.

In situ 3D nanoprinting of free-form coupling elements for hybrid photonic integration

NASA Astrophysics Data System (ADS)

Dietrich, P.-I.; Blaicher, M.; Reuter, I.; Billah, M.; Hoose, T.; Hofmann, A.; Caer, C.; Dangel, R.; Offrein, B.; Troppenz, U.; Moehrle, M.; Freude, W.; Koos, C.

2018-04-01

Hybrid photonic integration combines complementary advantages of different material platforms, offering superior performance and flexibility compared with monolithic approaches. This applies in particular to multi-chip concepts, where components can be individually optimized and tested. The assembly of such systems, however, requires expensive high-precision alignment and adaptation of optical mode profiles. We show that these challenges can be overcome by in situ printing of facet-attached beam-shaping elements. Our approach allows precise adaptation of vastly dissimilar mode profiles and permits alignment tolerances compatible with cost-efficient passive assembly techniques. We demonstrate a selection of beam-shaping elements at chip and fibre facets, achieving coupling efficiencies of up to 88% between edge-emitting lasers and single-mode fibres. We also realize printed free-form mirrors that simultaneously adapt beam shape and propagation direction, and we explore multi-lens systems for beam expansion. The concept paves the way to automated assembly of photonic multi-chip systems with unprecedented performance and versatility.

Effect of thread shape on screw stress concentration by photoelastic measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dragoni, E.

1994-11-01

The screw stress concentration for six nut-bolt connections embodying three different thread profiles and two nut shapes is measured photoelastically. Buttress (nearly zero flank angle), trapezoidal (15-deg flank angle), and triangular (30-deg flank angle) thread forms are examined in combination with standard and lip-type nuts. The effect of the thread profile on the screw stress concentration appears to be dependent upon the kind of nut considered. If the fastening incorporates a standard nut, the buttress thread is stronger than the triangular one, which, in turn, behaves better than the trapezoidal contour. The improvement is roughly a 20% reduction in themore » stress concentration factor from the trapezoidal to the buttress thread. In the case of lip nut, conversely, this tendency is somewhat reversed, with the trapezoidal thread performing slightly (but not decidedly) better than the other two shapes. Finally, averaged over all three thread forms, the lip nut exhibits a stress concentration factor which is about 50% lower than that of the standard nut.« less

Asymmetric crack propagation near waterfall cliff and its influence on the waterfall lip shape

NASA Astrophysics Data System (ADS)

Vastola, G.

2011-11-01

By means of Finite Element Method (FEM) calculations and fatigue fracture mechanics analysis, we show that crack propagation in bedrocks close to the waterfall cliff is preferential towards the cliff face rather than upstream the river. Based on this effect, we derive the corresponding expression for the velocity of recession vr of the waterfall lip, and find that vr has a quadratic dependence on the hydrostatic pressure. Quantitatively, this erosion mechanism generates recession rates of the order of ~cm-dm/y, consistent with the recession rates of well-known waterfalls. We enclose our expression for vr into a growth model to investigate the time evolution of a waterfall lip subject to this erosional mechanism. Because of the dependence on hydrostatic pressure, the shape of the waterfall is influenced by the transverse profile of the river that generates the waterfall. If the river has a transverse concavity, the waterfall evolves a curved shape. Evolution for the case of meanders with asymmetric transverse profile is also given.

An axial temperature profile curvature criterion for the engineering of convex crystal growth interfaces in Bridgman systems

NASA Astrophysics Data System (ADS)

Peterson, Jeffrey H.; Derby, Jeffrey J.

2017-06-01

A unifying idea is presented for the engineering of convex melt-solid interface shapes in Bridgman crystal growth systems. Previous approaches to interface control are discussed with particular attention paid to the idea of a "booster" heater. Proceeding from the idea that a booster heater promotes a converging heat flux geometry and from the energy conservation equation, we show that a convex interface shape will naturally result when the interface is located in regions of the furnace where the axial thermal profile exhibits negative curvature, i.e., where d2 T / dz2 < 0 . This criterion is effective in explaining prior literature results on interface control and promising for the evaluation of new furnace designs. We posit that the negative curvature criterion may be applicable to the characterization of growth systems via temperature measurements in an empty furnace, providing insight about the potential for achieving a convex interface shape, without growing a crystal or conducting simulations.

Dependence of recycling and edge profiles on lithium evaporation in high triangularity, high performance NSTX H-mode discharges.

DOE PAGES

Maingi, R.; Osborne, T. H.; Bell, M. G.; ...

2014-11-04

In this paper, the effects of a pre-discharge lithium evaporation variation on highly shaped discharges in the National Spherical Torus Experiment (NSTX) are documented. Lithium wall conditioning (‘dose’) was routinely applied onto graphite plasma facing components between discharges in NSTX, partly to reduce recycling. Reduced D α emission from the lower and upper divertor and center stack was observed, as well as reduced midplane neutral pressure; the magnitude of reduction increased with the pre-discharge lithium dose. Improved energy confinement, both raw τ E and H-factor normalized to scalings, with increasing lithium dose was also observed. At the highest doses, wemore » also observed elimination of edge-localized modes. The midplane edge plasma profiles were dramatically altered, comparable to lithium dose scans at lower shaping, where the strike point was farther from the lithium deposition centroid. As a result, this indicates that the benefits of lithium conditioning should apply to the highly shaped plasmas planned in NSTX-U.« less

Shape control of slack space reflectors using modulated solar pressure.

PubMed

Borggräfe, Andreas; Heiligers, Jeannette; Ceriotti, Matteo; McInnes, Colin R

2015-07-08

The static deflection profile of a large spin-stabilized space reflector because of solar radiation pressure acting on its surface is investigated. Such a spacecraft consists of a thin reflective circular film, which is deployed from a supporting hoop structure in an untensioned, slack manner. This paper investigates the use of a variable reflectivity distribution across the surface to control the solar pressure force and hence the deflected shape. In this first analysis, the film material is modelled as one-dimensional slack radial strings with no resistance to bending or transverse shear, which enables a semi-analytic derivation of the nominal deflection profile. An inverse method is then used to find the reflectivity distribution that generates a specific, for example, parabolic deflection shape of the strings. Applying these results to a parabolic reflector, short focal distances can be obtained when large slack lengths of the film are employed. The development of such optically controlled reflector films enables future key mission applications such as solar power collection, radio-frequency antennae and optical telescopes.

A model of transverse fuel injection applied to the computation of supersonic combustor flow

NASA Technical Reports Server (NTRS)

Rogers, R. C.

1979-01-01

A two-dimensional, nonreacting flow model of the aerodynamic interaction of a transverse hydrogen jet within a supersonic mainstream has been developed. The model assumes profile shapes of mass flux, pressure, flow angle, and hydrogen concentration and produces downstream profiles of the other flow parameters under the constraints of the integrated conservation equations. These profiles are used as starting conditions for an existing finite difference parabolic computer code for the turbulent supersonic combustion of hydrogen. Integrated mixing and flow profile results obtained from the computer code compare favorably with existing data for the supersonic combustion of hydrogen.

Spectral analysis of aeromagnetic profiles for depth estimation principles, software, and practical application

USGS Publications Warehouse

Sadek, H.S.; Rashad, S.M.; Blank, H.R.

1984-01-01

If proper account is taken of the constraints of the method, it is capable of providing depth estimates to within an accuracy of about 10 percent under suitable circumstances. The estimates are unaffected by source magnetization and are relatively insensitive to assumptions as to source shape or distribution. The validity of the method is demonstrated by analyses of synthetic profiles and profiles recorded over Harrat Rahat, Saudi Arabia, and Diyur, Egypt, where source depths have been proved by drilling.

Modifications to the edge current profile with auxiliary edge current drive and improved confinement in a reversed-field pinch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, B.E.; Biewer, T.M.; Chattopadhyay, P.K.

2000-09-01

Auxiliary edge current drive is routinely applied in the Madison Symmetric Torus [R.N. Dexter, D. W. Kerst, T.W. Lovell et.al., Fusion Technol. 19, 131 (1991)] with the goal of modifying the parallel current profile to reduce current- driven magnetic fluctuations and the associated particle and energy transport. Provided by an inductive electric field, the current drive successfully reduces energy transport. First-time measurements of the modified edge current profile reveal that, relative to discharges without auxiliary current drive, the edge current density decreases. This decrease is explicable in terms of newly measured reductions in the dynamo (fluctuation-based) electric field and themore » electrical conductivity. Induced by the current drive, these two changes to the edge plasma play as much of a role in determining the resultant edge current profile as does the current drive itself.« less

Application of the Hartmann–Tran profile to precise experimental data sets of 12C 2H 2

DOE PAGES

Forthomme, D.; Cich, M. J.; Twagirayezu, S.; ...

2015-06-25

Self- and nitrogen-broadened line shape data for the P e(11) line of the ν₁ + ν₃ band of acetylene, recorded using a frequency comb-stabilized laser spectrometer, have been analyzed using the Hartmann–Tran profile (HTP) line shape model in a multispectrum fitting. In total, the data included measurements recorded at temperatures between 125 K and 296 K and at pressures between 4 and 760 Torr. New, sub-Doppler, frequency comb-referenced measurements of the positions of multiple underlying hot band lines have also been made. These underlying lines significantly affect the P e(11) line profile at temperatures above 240 K and poorly knownmore » frequencies previously introduced errors into the line shape analyses. Thus, the behavior of the HTP model was compared to the quadratic speed dependent Voigt profile (QSDVP) expressed in the frequency and time domains. A parameter uncertainty analysis was carried out using a Monte Carlo method based on the estimated pressure, transmittance and frequency measurement errors. From the analyses, the P e(11) line strength was estimated to be 1.2014(50) × 10 -20 in cm.molecules⁻¹ units at 296 K with the standard deviation in parenthesis. For analyzing these data, we found that a reduced form of the HTP, equivalent to the QSDVP, was most appropriate because the additional parameters included in the full HTP were not well determined. As a supplement to this work, expressions for analytic derivatives and a lineshape fitting code written in Matlab for the HTP are available.« less

Application of the Hartmann-Tran profile to precise experimental data sets of 12C2H2

NASA Astrophysics Data System (ADS)

Forthomme, D.; Cich, M. J.; Twagirayezu, S.; Hall, G. E.; Sears, T. J.

2015-11-01

Self- and nitrogen-broadened line shape data for the Pe(11) line of the ν1 +ν3 band of acetylene, recorded using a frequency comb-stabilized laser spectrometer, have been analyzed using the Hartmann-Tran profile (HTP) line shape model in a multispectrum fitting. In total, the data included measurements recorded at temperatures between 125 K and 296 K and at pressures between 4 and 760 Torr. New, sub-Doppler, frequency comb-referenced measurements of the positions of multiple underlying hot band lines have also been made. These underlying lines significantly affect the Pe(11) line profile at temperatures above 240 K and poorly known frequencies previously introduced errors into the line shape analyses. The behavior of the HTP model was compared to the quadratic speed dependent Voigt profile (QSDVP) expressed in the frequency and time domains. A parameter uncertainty analysis was carried out using a Monte Carlo method based on the estimated pressure, transmittance and frequency measurement errors. From the analyses, the Pe(11) line strength was estimated to be 1.2014(50) ×10-20 in cmmolecule-1 units at 296 K with the standard deviation in parenthesis. For analyzing these data, we found that a reduced form of the HTP, equivalent to the QSDVP, was most appropriate because the additional parameters included in the full HTP were not well determined. As a supplement to this work, expressions for analytic derivatives and a lineshape fitting code written in Matlab for the HTP are available.

Phillips-Tikhonov regularization with a priori information for neutron emission tomographic reconstruction on Joint European Torus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bielecki, J.; Scholz, M.; Drozdowicz, K.

A method of tomographic reconstruction of the neutron emissivity in the poloidal cross section of the Joint European Torus (JET, Culham, UK) tokamak was developed. Due to very limited data set (two projection angles, 19 lines of sight only) provided by the neutron emission profile monitor (KN3 neutron camera), the reconstruction is an ill-posed inverse problem. The aim of this work consists in making a contribution to the development of reliable plasma tomography reconstruction methods that could be routinely used at JET tokamak. The proposed method is based on Phillips-Tikhonov regularization and incorporates a priori knowledge of the shape ofmore » normalized neutron emissivity profile. For the purpose of the optimal selection of the regularization parameters, the shape of normalized neutron emissivity profile is approximated by the shape of normalized electron density profile measured by LIDAR or high resolution Thomson scattering JET diagnostics. In contrast with some previously developed methods of ill-posed plasma tomography reconstruction problem, the developed algorithms do not include any post-processing of the obtained solution and the physical constrains on the solution are imposed during the regularization process. The accuracy of the method is at first evaluated by several tests with synthetic data based on various plasma neutron emissivity models (phantoms). Then, the method is applied to the neutron emissivity reconstruction for JET D plasma discharge #85100. It is demonstrated that this method shows good performance and reliability and it can be routinely used for plasma neutron emissivity reconstruction on JET.« less

Size and shape-dependent cytotoxicity profile of gold nanoparticles for biomedical applications.

PubMed

Woźniak, Anna; Malankowska, Anna; Nowaczyk, Grzegorz; Grześkowiak, Bartosz F; Tuśnio, Karol; Słomski, Ryszard; Zaleska-Medynska, Adriana; Jurga, Stefan

2017-06-01

Metallic nanoparticles, in particular gold nanoparticles (AuNPs), offer a wide spectrum of applications in biomedicine. A crucial issue is their cytotoxicity, which depends greatly on various factors, including morphology of nanoparticles. Because metallic nanoparticles have an effect on cell membrane integrity, their shape and size may affect the viability of cells, due to their different geometries as well as physical and chemical interactions with cell membranes. Variations in the size and shape of gold nanoparticles may indicate particular nanoparticle morphologies that provide strong cytotoxicity effects. Synthesis of different sized and shaped bare AuNPs was performed with spherical (~ 10 nm), nanoflowers (~ 370 nm), nanorods (~ 41 nm), nanoprisms (~ 160 nm) and nanostars (~ 240 nm) morphologies. These nanostructures were characterized and interacting with cancer (HeLa) and normal (HEK293T) cell lines and cell viability tests were performed by WST-1 tests and fluorescent live/dead cell imaging experiments. It was shown that various shapes and sizes of gold nanostructures may affect the viability of the cells. Gold nanospheres and nanorods proved to be more toxic than star, flower and prism gold nanostructures. This may be attributed to their small size and aggregation process. This is the first report concerning a comparison of cytotoxic profile in vitro with a wide spectrum of bare AuNPs morphology. The findings show their possible use in biomedical applications.

Jet Mixing in Direct-Chill Casting of Aluminum: Crater Effects and its Consequence on Centerline Segregation

NASA Astrophysics Data System (ADS)

Wagstaff, Samuel R.; Allanore, Antoine

2017-08-01

Recent reports have demonstrated the possibility of mitigating macrosegregation during the Direct-Chill casting of rolling slab ingots using an impinging jet. Herein, an analytical model is presented to predict the shape of the crater formed due to the impact of the jet on the slurry region. The model takes into account alloy composition, physical dimension, and casting speed on the distribution of forces and crater shape. The calculated shape of the crater profile is used to explain the centerline depletion in the impingement region previously reported.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Chien-Chih; Hsu, Pei-Lun; Lin, Li

A particular edge-dependent inversion current behavior of metal-oxide-semiconductor (MOS) tunneling diodes was investigated utilizing square and comb-shaped electrodes. The inversion tunneling current exhibits the strong dependence on the tooth size of comb-shaped electrodes and oxide thickness. Detailed illustrations of current conduction mechanism are developed by simulation and experimental measurement results. It is found that the electron diffusion current and Schottky barrier height lowering for hole tunneling current both contribute on inversion current conduction. In MOS tunneling photodiode applications, the photoresponse can be improved by decreasing SiO{sub 2} thickness and using comb-shaped electrodes with smaller tooth spacing. Meantime, the high andmore » steady photosensitivity can also be approached by introducing HfO{sub 2} into dielectric stacks.« less

Seasonal variability of aerosol vertical profiles over east US and west Europe: GEOS-Chem/APM simulation and comparison with CALIPSO observations

NASA Astrophysics Data System (ADS)

Ma, Xiaoyan; Yu, Fangqun

2014-04-01

In this study, we employed 5 years (2007-2011) of the CALIPSO level-3 monthly aerosol extinction product to compare with the GEOS-Chem/APM simulations for the same time period over two major industrial regions (east US and west Europe). The objective is to understand which aerosol types or species significantly determine the vertical profiles by comparing the seasonal variability between the simulations and observations. Our study shows that the model successfully produces the magnitude of aerosol extinction, profile shape, and their seasonal variability observed by CALIPSO over both east US (EUS) and west Europe (WEU). The extinctions below 1 km make up 44-79% to the total, from either the model simulations or satellite retrievals, with larger percentages in winter seasons (62-79%) and smaller percentages in summer seasons (44-57%) associated with the strength of vertical transport. The shape of the vertical profiles has, therefore, a distinct seasonal variability, with a more like quasi-exponential shape in DJF (December, January, and February) and SON (September, October, and November) than in MAM (March, April, and May) and JJA (June, July, and August), which have been discerned from both measurements and simulations. Analysis of modeled aerosol species indicates that secondary particles (SP), containing sulfate, ammonia, nitrate, and secondary organic aerosols (SOAs), predominantly determine the total aerosol vertical profiles while black carbon (BC), primary organic carbon (OC), and sea salt (SS), only account for a small fraction and are also limited near the surface. Mineral dust (DS) contributes more to the total extinction over WEU than over EUS, particularly in MAM, a result of being adjacent to the North Africa desert. Secondary inorganic aerosol (SIA, i.e. sulfate, ammonia, and nitrate) contributes most of the total SP mass in DJF and SON while SOA is particularly important in MAM and JJA when the emissions from leafed plants are active. Our study also indicates that, compared to aerosol extinction, the number concentration of particles larger than 10 nm (CN10) exhibits a different seasonal variation and vertical profile, but Cloud Condensation Nuclei (CCN) concentration at supersaturation of 0.4% (CCN0.4) presents a consistent seasonal variation and similar vertical profile. Therefore, aerosol extinction could be a good indicator for CCN0.4 with regard to seasonal variations of vertical profiles.

Shaping the beam profile of a partially coherent beam by a phase aperture

NASA Astrophysics Data System (ADS)

Wu, Gaofeng; Cai, Yangjian; Chen, Jun

2011-08-01

By use of a tensor method, an analytical formula for a partially coherent Gaussian Schell-model (GSM) beam truncated by a circular phase aperture propagating through a paraxial ABCD optical system is derived. The propagation properties of a GSM beam truncated by a circular phase aperture in free space are studied numerically. It is found that the circular phase aperture can be used to shape the beam profile of a GSM beam and generate partially coherent dark hollow or flat-topped beam, which is useful in many applications, e.g., optical trapping, free-space optical communication, and material thermal processing. The propagation factor of a GSM beam truncated by a circular phase aperture is also analyzed.

Shaping of Rack Cutter Original Profile for Fine-module Ratchet Teeth Cutting

NASA Astrophysics Data System (ADS)

Sharkov, O. V.; Koryagin, S. I.; Velikanov, N. L.

2018-05-01

The design models and the process of shaping the cutting edges of the rack cutter for cutting fine-module ratchet teeth are considered in the article. The use of fine-module ratchet teeth can reduce the noise and impact loads during operation of the freewheel mechanisms. Mathematical dependencies for calculating the coordinates determining the geometric position of the points of the front and back edges of the cutting profile of the rack cutter, the workpiece angle of rotation during cutting the ratchet teeth were obtained. When applying the developed method, the initial data are: the radii of the workpiece circumferences passing through the dedendum of the external and internal cut teeth; gradient angles of the front and back edges of the rail.

Use of pattern recognition and neural networks for non-metric sex diagnosis from lateral shape of calvarium: an innovative model for computer-aided diagnosis in forensic and physical anthropology.

PubMed

Cavalli, Fabio; Lusnig, Luca; Trentin, Edmondo

2017-05-01

Sex determination on skeletal remains is one of the most important diagnosis in forensic cases and in demographic studies on ancient populations. Our purpose is to realize an automatic operator-independent method to determine the sex from the bone shape and to test an intelligent, automatic pattern recognition system in an anthropological domain. Our multiple-classifier system is based exclusively on the morphological variants of a curve that represents the sagittal profile of the calvarium, modeled via artificial neural networks, and yields an accuracy higher than 80 %. The application of this system to other bone profiles is expected to further improve the sensibility of the methodology.

Carbon Dioxide Line Shapes for Atmospheric Remote Sensing

NASA Astrophysics Data System (ADS)

Predoi-Cross, Adriana; Ibrahim, Amr; Wismath, Alice; Teillet, Philippe M.; Devi, V. Malathy; Benner, D. Chris; Billinghurst, Brant

2010-02-01

We present a detailed spectroscopic study of carbon dioxide in support of atmospheric remote sensing. We have studied two weak absorption bands near the strong ν2 band that is used to derive atmospheric temperature profiles. We have analyzed our laboratory spectra recorded with the synchrotron and globar sources with spectral line profiles that reproduce the absorption features with high accuracy. The Q-branch transitions exhibited asymmetric line shape due to weak line-mixing. For these weak transitions, we have retrieved accurate experimental line strengths, self- and air-broadening, self- and air-induced shift coefficients and weak line mixing parameters. The experimental precision is sufficient to reveal inherent variations of the width and shift coefficients according to transition quantum numbers.

Structure, distribution, and evolution history of the Early Holocene erosional mud ridge system on the inner East China Sea shelf near the Yangtze River estuary

NASA Astrophysics Data System (ADS)

Feng, Zhibing; Liu, Baohua; Zhao, Yuexia; Li, Xishuang; Dada, Olusegun A.; Jiang, Li; Si, Shaokun

2017-04-01

Utilizing the collected high-resolution seismic dataset and accompanying borehole and bathymetric data, we systematically evaluated the morphology, architecture, sedimentology, and evolution of erosional mud ridges within the inner East China Sea (ECS) shelf. We identified 20 mud ridges, i.e., seismic reflection profile crossings of exposed or buried mud ridges, which are 3.0-30.1 km in width and 2.5-17.3 m in height. The mud ridges are composed predominantly of gray clayey silt, and on seismic profiles contain parallel to subparallel reflectors. They formed around 10-12 ka BP within an estuarine environment. Scouring features of some mud ridges on the eastern part of the study area can be recognized. Consideration of the relative positions of mud ridges, together with the topographical features, enables us to map four linear mud ridges (LMRs). The SE-NW oriented LMRs are > 50 km in length, 3.0-9.5 km in width and running parallel to each other. They also display asymmetric shapes, with steeper slopes to the SW. The eastern segments of some LMRs are exposed on the present seafloor whereas other segments are mainly overlain by the mid- and late Holocene strata. Since the LMRs share similarities with the modern tidal sand ridges in shape and orientation, we hypothesize that they are formed under a uniform tidal current. Seismic data highlight that the internal reflectors of sand ridges consist of dipping clinoforms and are significantly different from LMRs, a feature which is largely due to the difference in grain-size composition of sediments between the inner and mid-outer ECS shelf. The mid- to outer ECS shelf is capped by coarser-grained sediments (i.e., medium to fine-grained), which were reworked and deposited at locations near the erosional areas under a polycyclic tidal current, thus forming multiphase sand ridges. However, fine-grained sediments (i.e., silty clay and clayey silt) overlain on the inner ECS shelf with light mass were carried far away from the erosional areas by the tidal currents, and the relict mud ridges were built. Evidence shows that the LMRs were formed by the early Holocene strata being scoured by a persistent southeasterly flowing current during 8-10 ka BP. The evolution of the LMRs occurred in three stages: (a) formation of the transgressional strata at 10-12 ka BP, (b) strong trough erosion at 8-10 ka BP, and (c) local adjustment (i.e., local erosion slightly and preservation) after 8 ka BP.

Performance Assessment of Model-Based Optimal Feedforward and Feedback Current Profile Control in NSTX-U using the TRANSP Code

NASA Astrophysics Data System (ADS)

Ilhan, Z.; Wehner, W. P.; Schuster, E.; Boyer, M. D.; Gates, D. A.; Gerhardt, S.; Menard, J.

2015-11-01

Active control of the toroidal current density profile is crucial to achieve and maintain high-performance, MHD-stable plasma operation in NSTX-U. A first-principles-driven, control-oriented model describing the temporal evolution of the current profile has been proposed earlier by combining the magnetic diffusion equation with empirical correlations obtained at NSTX-U for the electron density, electron temperature, and non-inductive current drives. A feedforward + feedback control scheme for the requlation of the current profile is constructed by embedding the proposed nonlinear, physics-based model into the control design process. Firstly, nonlinear optimization techniques are used to design feedforward actuator trajectories that steer the plasma to a desired operating state with the objective of supporting the traditional trial-and-error experimental process of advanced scenario planning. Secondly, a feedback control algorithm to track a desired current profile evolution is developed with the goal of adding robustness to the overall control scheme. The effectiveness of the combined feedforward + feedback control algorithm for current profile regulation is tested in predictive simulations carried out in TRANSP. Supported by PPPL.

Convergence to a pulsating travelling wave for an epidemic reaction-diffusion system with non-diffusive susceptible population.

PubMed

Ducrot, Arnaud; Giletti, Thomas

2014-09-01

In this work we study the asymptotic behaviour of the Kermack-McKendrick reaction-diffusion system in a periodic environment with non-diffusive susceptible population. This problem was proposed by Kallen et al. as a model for the spatial spread for epidemics, where it can be reasonable to assume that the susceptible population is motionless. For arbitrary dimensional space we prove that large classes of solutions of such a system have an asymptotic spreading speed in large time, and that the infected population has some pulse-like asymptotic shape. The analysis of the one-dimensional problem is more developed, as we are able to uncover a much more accurate description of the profile of solutions. Indeed, we will see that, for some initially compactly supported infected population, the profile of the solution converges to some pulsating travelling wave with minimal speed, that is to some entire solution moving at a constant positive speed and whose profile's shape is periodic in time.

Calculation of catalyst crust thickness from full elemental laser-induced breakdown spectroscopy images

NASA Astrophysics Data System (ADS)

Sorbier, L.; Trichard, F.; Moncayo, S.; Lienemann, C. P.; Motto-Ros, V.

2018-01-01

We propose a methodology to compute the crust thickness of an element in an egg-shell catalyst from a two-dimensional elemental map. The methodology handles two important catalyst shapes: infinite extrudates of arbitrary section and spheres. The methodology is validated with synthetic analytical profiles on simple shapes (cylinder and sphere). Its relative accuracy is shown close to few percent with a decrease inversely proportional to the square root of the number of sampled pixels. The crust thickness obtained by this method from quantitative Pd maps acquired by laser-induced breakdown spectroscopy are comparable with values obtained from electron-probe microanalysis profiles. Some discrepancies are found and are explained by the heterogeneity of the crust thickness within a grain. As a full map is more representative than a single profile, fast mapping and the methodology exposed in this paper are expected to become valuable tools for the development of new generations of egg-shell deposited catalysts.

Monitoring of Time-Dependent System Profiles by Multiplex Gas Chromatography with Maximum Entropy Demodulation

NASA Technical Reports Server (NTRS)

Becker, Joseph F.; Valentin, Jose

1996-01-01

The maximum entropy technique was successfully applied to the deconvolution of overlapped chromatographic peaks. An algorithm was written in which the chromatogram was represented as a vector of sample concentrations multiplied by a peak shape matrix. Simulation results demonstrated that there is a trade off between the detector noise and peak resolution in the sense that an increase of the noise level reduced the peak separation that could be recovered by the maximum entropy method. Real data originated from a sample storage column was also deconvoluted using maximum entropy. Deconvolution is useful in this type of system because the conservation of time dependent profiles depends on the band spreading processes in the chromatographic column, which might smooth out the finer details in the concentration profile. The method was also applied to the deconvolution of previously interpretted Pioneer Venus chromatograms. It was found in this case that the correct choice of peak shape function was critical to the sensitivity of maximum entropy in the reconstruction of these chromatograms.

Ultra-compact Marx-type high-voltage generator

DOEpatents

Goerz, David A.; Wilson, Michael J.

2000-01-01

An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

Shaping ability and safety of five different rotary nickel-titanium instruments compared with stainless steel hand instrumentation in simulated curved root canals.

PubMed

Schirrmeister, Jörg F; Strohl, Christian; Altenburger, Markus J; Wrbas, Karl-Thomas; Hellwig, Elmar

2006-06-01

To compare the shaping ability and safety of engine-driven FlexMaster, GT Rotary, ProFile, ProTaper, and RaCe rotary instrumentation and Hedström hand instrumentation in simulated root canals. One hundred fifty simulated colored root canals with a curvature of 20 degrees and a radius of 10 mm were randomly distributed among 6 groups of 25 specimens each. After preparation to apical size 30 the area of remaining color on the canal wall indicating unprepared areas was measured in mm2 using image analyzer software. Specimens treated with RaCe left least areas of remaining color compared to all other groups (P < .001), followed by ProTaper. Preparation with ProFile left behind the highest amount of unprepared areas. The ProFile group revealed significantly more remaining color than ProTaper, GT Rotary, and FlexMaster (P < .05). Four FlexMaster files separated. RaCe rotary files were safe and more effective compared to the other instruments.

Airfoil shape for a turbine bucket

DOEpatents

Hyde, Susan Marie; By, Robert Romany; Tressler, Judd Dodge; Schaeffer, Jon Conrad; Sims, Calvin Levy

2005-06-28

Third stage turbine buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth Table I wherein X and Y values are in inches and the Z values are non-dimensional values from 0 to 0.938 convertible to Z distances in inches by multiplying the Z values by the height of the airfoil in inches. The X and Y values are distances which, when connected by smooth continuing arcs, define airfoil profile sections at each distance Z. The profile sections at each distance Z are joined smoothly to one another to form a complete airfoil shape. The X and Y distances may be scalable as a function of the same constant or number to provide a scaled up or scaled down airfoil section for the bucket. The nominal airfoil given by the X, Y and Z distances lies within an envelop of .+-.0.150 inches in directions normal to the surface of the airfoil.

Correlation of ion and beam current densities in Kaufman thrusters.

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1973-01-01

In the absence of direct impingement erosion, electrostatic thruster accelerator grid lifetime is defined by the charge exchange erosion that occurs at peak values of the ion beam current density. In order to maximize the thrust from an engine with a specified grid lifetime, the ion beam current density profile should therefore be as flat as possible. Knauer (1970) has suggested this can be achieved by establishing a radial plasma uniformity within the thruster discharge chamber; his tests with the radial field thruster provide an example of uniform plasma properties within the chamber and a flat ion beam profile occurring together. It is shown that, in particular, the ion density profile within the chamber determines the beam current density profile, and that a uniform ion density profile at the screen grid end of the discharge chamber should lead to a flat beam current density profile.

Latest developments on fibered MOPA in mJ range with hollow-core fiber beam delivery and fiber beam shaping used as seeder for large scale laser facilities (Conference Presentation)

NASA Astrophysics Data System (ADS)

Gleyze, Jean-François; Scol, Florent; Perrin, Arnaud; Gouriou, Pierre; Valentin, Constance; Bouwmans, Géraud; Hugonnot, Emmanuel

2017-05-01

The Laser Megajoule (LMJ) is a French large scale laser facility dedicated to inertial fusion and plasma physics research. LMJ front-ends are based on fiber laser technology at nanojoule range [1]. Scaling the energy of those fiber seeders to the millijoule range is a way to upgrade LMJ's front ends architecture and could also be used as seeder for lasers for ELI project for example. However, required performances are so restrictive (optical-signal-to-noise ratio higher than 50 dB, temporally-shaped nanosecond pulses and spatial single-mode top-hat beam output) that such fiber systems are very tricky to build. High-energy fiber amplifiers In 2015, we have demonstrated, an all-fiber MOPA prototype able to produce a millijoule seeder, but unfortunately not 100% conform for all LMJ's performances. A major difficulty was to manage the frequency modulation used to avoid stimulated Brillouin scattering, to amplitude modulation (FM-AM) conversion, this limits the energy at 170µJ. For upgrading the energy to the millijoule range, it's necessary to use an amplifier with a larger core fiber. However, this fiber must still be flexible; polarization maintaining and exhibit a strictly single-mode behaviour. We are thus developing a new amplifier architecture based on an Yb-doped tapered fiber: its core diameter is from a narrow input to a wide output (MFD 8 to 26 µm). A S² measurement on a 2,5m long tapered fiber rolled-up on 22 cm diameter confirmed that this original geometry allows obtaining strictly single-mode behaviour. In a 1 kHz repetition rate regime, we already obtain 750 µJ pulses, and we are on the way to mJ, respecting LMJ performances. Beam delivery In LMJ architecture the distance between the nanojoule fiber seeder and the amplifier stages is about 16 m. Beam delivery is achieved with a standard PM fiber, such a solution is no longer achievable with hundreds of kilowatt peak powers. An efficient way to minimize nonlinear effects is to use hollow-core (HC) fibers. The comparison between the different fibers will be presented in the conference. Fiber spatial beam shaping Spatial beam shaping (top-hat profile) is mandatory to optimize the energy extraction in free-space amplifier. It would be very interesting to obtain a flat-top beam in an all-fiber way. Accordingly, we have design and realize a large mode area single-mode top-hat fiber able to deliver a coherent top-hat beam. This fiber, with larger MFD adapted to mJ pulse, will be implemented to perform the spatial beam shaping from coherent Gaussian profile to coherent top-hat intensity profile in the mJ range. In conclusion, we will present an all-fiber MOPA built to fulfil stringent requirements for large scale laser facility seeding. We have already achieved 750 µJ with 10 ns square pulses. Transport of high peak power pulses over 17 m in a hollow-core fiber has been achieved and points out FM to AM conversion management issues. Moreover, spatial beam shaping is obtained by using specifically designed single-mode fibers. Various optimizations are currently under progress and will be presented.

Turbine blade profile design method based on Bezier curves

NASA Astrophysics Data System (ADS)

Alexeev, R. A.; Tishchenko, V. A.; Gribin, V. G.; Gavrilov, I. Yu.

2017-11-01

In this paper, the technique of two-dimensional parametric blade profile design is presented. Bezier curves are used to create the profile geometry. The main feature of the proposed method is an adaptive approach of curve fitting to given geometric conditions. Calculation of the profile shape is produced by multi-dimensional minimization method with a number of restrictions imposed on the blade geometry.The proposed method has been used to describe parametric geometry of known blade profile. Then the baseline geometry was modified by varying some parameters of the blade. The numerical calculation of obtained designs has been carried out. The results of calculations have shown the efficiency of chosen approach.

Neural network evaluation of tokamak current profiles for real time control

NASA Astrophysics Data System (ADS)

Wróblewski, Dariusz

1997-02-01

Active feedback control of the current profile, requiring real-time determination of the current profile parameters, is envisioned for tokamaks operating in enhanced confinement regimes. The distribution of toroidal current in a tokamak is now routinely evaluated based on external (magnetic probes, flux loops) and internal (motional Stark effect) measurements of the poloidal magnetic field. However, the analysis involves reconstruction of magnetohydrodynamic equilibrium and is too intensive computationally to be performed in real time. In the present study, a neural network is used to provide a mapping from the magnetic measurements (internal and external) to selected parameters of the safety factor profile. The single-pass, feedforward calculation of output of a trained neural network is very fast, making this approach particularly suitable for real-time applications. The network was trained on a large set of simulated equilibrium data for the DIII-D tokamak. The database encompasses a large variety of current profiles including the hollow current profiles important for reversed central shear operation. The parameters of safety factor profile (a quantity related to the current profile through the magnetic field tilt angle) estimated by the neural network include central safety factor, q0, minimum value of q, qmin, and the location of qmin. Very good performance of the trained neural network both for simulated test data and for experimental datais demonstrated.

Neural network evaluation of tokamak current profiles for real time control (abstract)

NASA Astrophysics Data System (ADS)

Wróblewski, Dariusz

1997-01-01

Active feedback control of the current profile, requiring real-time determination of the current profile parameters, is envisioned for tokamaks operating in enhanced confinement regimes. The distribution of toroidal current in a tokamak is now routinely evaluated based on external (magnetic probes, flux loops) and internal (motional Stark effect) measurements of the poloidal magnetic field. However, the analysis involves reconstruction of magnetohydrodynamic equilibrium and is too intensive computationally to be performed in real time. In the present study, a neural network is used to provide a mapping from the magnetic measurements (internal and external) to selected parameters of the safety factor profile. The single-pass, feedforward calculation of output of a trained neural network is very fast, making this approach particularly suitable for real-time applications. The network was trained on a large set of simulated equilibrium data for the DIII-D tokamak. The database encompasses a large variety of current profiles including the hollow current profiles important for reversed central shear operation. The parameters of safety factor profile (a quantity related to the current profile through the magnetic field tilt angle) estimated by the neural network include central safety factor, q0, minimum value of q, qmin, and the location of qmin. Very good performance of the trained neural network both for simulated test data and for experimental data is demonstrated.

Body dissatisfaction and the wish for different silhouette is associated with higher adiposity and fat intake in female ballet dancers than male.

PubMed

Da Silva, Camila Lacerda; De Oliveira, Erick Prado; De Sousa, Maysa Vieira; Pimentel, Gustavo D

2016-01-01

It is known that behavioral disorders and altered food intake are linked to ballet dancers. Thus, the aim of the present study was to investigate the body composition, dietetic profile, self-perceived body image and social desirability in professional ballet dancers. This study was conducted from April to October 2010 in athletes screened for nutritional evaluation. Anthropometric, dietary, social desirability and self-perceived body image evaluation were performed to attend the aim of study. We found that ballet dancers are highly trained and eutrophic, although female dancers had higher adiposity and fat intake than male dancers. In addition, it was observed low consumption of calcium, dietary fiber, potassium, magnesium and vitamin A. Moreover, 30% of male ballet dancers have a strong desire for social acceptance. When the body image was evaluated by Body Shape Questionnaire (BSQ), was reported that 40% of the ballet female dancers have of moderate to severe alteration in body image and 20% of male dancers had slight alteration. Furthermore, the Drawings and Silhouettes Scale showed that 80% of male dancers wish to have a smaller or larger silhouette than the current self-perceived and 60% of the female dancers would like to have a silhouette lower than the self-perceive as current. Collectively, our results shown that most of the dancers were eutrophic, but female athletes have higher adiposity and present strong desire for a different shape of current. Furthermore, was found increased fat intake in female group; however, deficiencies in consumption of dietary fiber, calcium, potassium, magnesium and vitamin A were found in both gender.

Overview of KSTAR initial operation

NASA Astrophysics Data System (ADS)

Kwon, M.; Oh, Y. K.; Yang, H. L.; Na, H. K.; Kim, Y. S.; Kwak, J. G.; Kim, W. C.; Kim, J. Y.; Ahn, J. W.; Bae, Y. S.; Baek, S. H.; Bak, J. G.; Bang, E. N.; Chang, C. S.; Chang, D. H.; Chavdarovski, I.; Chen, Z. Y.; Cho, K. W.; Cho, M. H.; Choe, W.; Choi, J. H.; Chu, Y.; Chung, K. S.; Diamond, P.; Do, H. J.; Eidietis, N.; England, A. C.; Grisham, L.; Hahm, T. S.; Hahn, S. H.; Han, W. S.; Hatae, T.; Hillis, D.; Hong, J. S.; Hong, S. H.; Hong, S. R.; Humphrey, D.; Hwang, Y. S.; Hyatt, A.; In, Y. K.; Jackson, G. L.; Jang, Y. B.; Jeon, Y. M.; Jeong, J. I.; Jeong, N. Y.; Jeong, S. H.; Jhang, H. G.; Jin, J. K.; Joung, M.; Ju, J.; Kawahata, K.; Kim, C. H.; Kim, D. H.; Kim, Hee-Su; Kim, H. S.; Kim, H. K.; Kim, H. T.; Kim, J. H.; Kim, J. C.; Kim, Jong-Su; Kim, Jung-Su; Kim, Kyung-Min; Kim, K. M.; Kim, K. P.; Kim, M. K.; Kim, S. H.; Kim, S. S.; Kim, S. T.; Kim, S. W.; Kim, Y. J.; Kim, Y. K.; Kim, Y. O.; Ko, W. H.; Kogi, Y.; Kong, J. D.; Kubo, S.; Kumazawa, R.; Kwak, S. W.; Kwon, J. M.; Kwon, O. J.; LeConte, M.; Lee, D. G.; Lee, D. K.; Lee, D. R.; Lee, D. S.; Lee, H. J.; Lee, J. H.; Lee, K. D.; Lee, K. S.; Lee, S. G.; Lee, S. H.; Lee, S. I.; Lee, S. M.; Lee, T. G.; Lee, W. C.; Lee, W. L.; Leur, J.; Lim, D. S.; Lohr, J.; Mase, A.; Mueller, D.; Moon, K. M.; Mutoh, T.; Na, Y. S.; Nagayama, Y.; Nam, Y. U.; Namkung, W.; Oh, B. H.; Oh, S. G.; Oh, S. T.; Park, B. H.; Park, D. S.; Park, H.; Park, H. T.; Park, J. K.; Park, J. S.; Park, K. R.; Park, M. K.; Park, S. H.; Park, S. I.; Park, Y. M.; Park, Y. S.; Patterson, B.; Sabbagh, S.; Saito, K.; Sajjad, S.; Sakamoto, K.; Seo, D. C.; Seo, S. H.; Seol, J. C.; Shi, Y.; Song, N. H.; Sun, H. J.; Terzolo, L.; Walker, M.; Wang, S. J.; Watanabe, K.; Welander, A. S.; Woo, H. J.; Woo, I. S.; Yagi, M.; Yaowei, Y.; Yonekawa, Y.; Yoo, K. I.; Yoo, J. W.; Yoon, G. S.; Yoon, S. W.; KSTAR Team

2011-09-01

Since the successful first plasma generation in the middle of 2008, three experimental campaigns were successfully made for the KSTAR device, accompanied with a necessary upgrade in the power supply, heating, wall-conditioning and diagnostic systems. KSTAR was operated with the toroidal magnetic field up to 3.6 T and the circular and shaped plasmas with current up to 700 kA and pulse length of 7 s, have been achieved with limited capacity of PF magnet power supplies. The mission of the KSTAR experimental program is to achieve steady-state operations with high performance plasmas relevant to ITER and future reactors. The first phase (2008-2012) of operation of KSTAR is dedicated to the development of operational capabilities for a super-conducting device with relatively short pulse. Development of start-up scenario for a super-conducting tokamak and the understanding of magnetic field errors on start-up are one of the important issues to be resolved. Some specific operation techniques for a super-conducting device are also developed and tested. The second harmonic pre-ionization with 84 and 110 GHz gyrotrons is an example. Various parameters have been scanned to optimize the pre-ionization. Another example is the ICRF wall conditioning (ICWC), which was routinely applied during the shot to shot interval. The plasma operation window has been extended in terms of plasma beta and stability boundary. The achievement of high confinement mode was made in the last campaign with the first neutral beam injector and good wall conditioning. Plasma control has been applied in shape and position control and now a preliminary kinetic control scheme is being applied including plasma current and density. Advanced control schemes will be developed and tested in future operations including active profiles, heating and current drives and control coil-driven magnetic perturbation.

The Chandra/MOST Campaign on Delta Ori A

NASA Astrophysics Data System (ADS)

Corcoran, Michael

2014-11-01

X-ray emission from massive stars is produced by shocked gas distributed throughout their unstable stellar winds. These shocks play a significant role in determining accurate stellar mass loss rates. Our current understanding of these shocks is derived from indirect indicators like line profile shapes and the f/i ratio of the He-like triplets. Here we discuss a campaign of phase-resolved Chandra grating observations and simultaneous high-precision photometry using the MOST satellite of the massive binary Delta Ori A, in an attempt to directly constrain the radial extent of the hot gas in the wind of the primary star (Delta Ori Aa) via occultation by the X-ray faint secondary (Delta Ori Ab). We present an overview of this campaign and a summary of our results.

Molecular filter-based diagnostics in high speed flows

NASA Technical Reports Server (NTRS)

Elliott, Gregory S.; Samimy, MO; Arnette, Stephen A.

1993-01-01

The use of iodine molecular filters in nonintrusive planar velocimetry methods is examined. Detailed absorption profiles are obtained to highlight the effects that determine the profile shape. It is shown that pressure broadening induced by the presence of a nonabsorbing vapor can be utilized to significantly change the slopes bounding the absorbing region while remaining in the optically-thick regime.

Plasma oscillations in spherical Gaussian shaped ultracold neutral plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Tianxing; Lu, Ronghua, E-mail: lurh@siom.ac.cn; Guo, Li

2016-04-15

The collective plasma oscillations are investigated in ultracold neutral plasma with a non-uniform density profile. Instead of the plane configuration widely used, we derive the plasma oscillation equations with spherically symmetric distribution and Gaussian density profile. The damping of radial oscillation is found. The Tonks–Dattner resonances of the ultracold neutral plasma with an applied RF field are also calculated.

Optimization of Root Section for Ultra-long Steam Turbine Rotor Blade

NASA Astrophysics Data System (ADS)

Hála, Jindřich; Luxa, Martin; Šimurda, David; Bobčík, Marek; Novák, Ondřej; Rudas, Bartoloměj; Synáč, Jaroslav

2018-04-01

This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Mach number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements (optical and pneumatic).