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Sample records for facing step channel

  1. Dynamics of flow behind backward-facing step in a narrow channel

    NASA Astrophysics Data System (ADS)

    Uruba, V.

    2013-04-01

    The results and their analysis from experiments obtained by TR-PIV are presented on the model of backward-facing step in a narrow channel. The recirculation zone is studied in details. Mean structures are evaluated from fluctuating velocity fields. Then dynamics of the flow is characterized with help of POD (BOD) technique. Substantial differences in high energy dynamical structures behaviour within the back-flow region and further downstream behind the flow reattachment have been found.

  2. Finite analytic numerical solution of two-dimensional channel flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Ho, K.-S.; Chen, C.-J.

    1986-01-01

    Laminar channel flow over a backward-facing step is investigated. The finite analytic (FA) method is used to obtain the numerical solution. The FA solutions predict the recirculation zone lengths and the recirculated mass flow rates for Reynolds numbers, Re, of 25, 50, 73, 125, 191 and 229 which correlate well with experimental measurements. The general flow patterns of the recirculation region flows for the Reynolds numbers considered in this study are similar to each other.

  3. Triple-velocity products in a channel with a backward-facing step

    NASA Technical Reports Server (NTRS)

    Amano, R. S.; Goel, P.

    1986-01-01

    Attention is given to the evaluation of tripple velocity products in the reattaching and developing region behind a backward facing step. The change in tripple velocity products is significant in the wake region, yielding substantial variation in the diffusion rate of the Reynolds stresses. Four models of the third-order closure are examined, and the results are compared with the experimental data for Chandrsuda and Bradshaw (1980).

  4. Three dimensional numerical investigations on the heat transfer enhancement in a triangular facing step channels using nanofluid

    NASA Astrophysics Data System (ADS)

    Mohammed, K. A.; Abu Talib, A. R.; Aziz, N. Abdul; Ahmed, K. A.

    2016-10-01

    In this paper, laminar flow for the distilled and SiO2-water nanofluid flow and heat transfer were numerically investigated in three-dimensional triangular facing-step channel. The nanoparticle volume fraction and Reynolds number considered are in the range of 0-1% and 100-1500, respectively. Numerical solutions are obtained by using finite difference method to solve the governing equations. The effects of the volume fraction of nanoparticle, triangular facing-step channel amplitude height, wavelength and Reynolds number on local skin-friction coefficient, average Nusselt number and enhancement of heat transfer are presented and discussed. The results show that the Nusselt number and friction coefficient increases as the amplitude height of triangle channel increases. As the nanoparticle volume fraction increases, the Nusselt number is also found to be significantly increased, accompanied by only a slight increase in the friction coefficient. In addition, it is found that the heat transfer enhancement mainly depends on the amplitude height of the triangle wall, nanoparticle volume fraction and Reynolds number rather than the wavelength.

  5. Investigation of obstacle effect to improve conjugate heat transfer in backward facing step channel using fast simulation of incompressible flow

    NASA Astrophysics Data System (ADS)

    Nouri-Borujerdi, Ali; Moazezi, Arash

    2017-07-01

    The current study investigates the conjugate heat transfer characteristics for laminar flow in backward facing step channel. All of the channel walls are insulated except the lower thick wall under a constant temperature. The upper wall includes a insulated obstacle perpendicular to flow direction. The effect of obstacle height and location on the fluid flow and heat transfer are numerically explored for the Reynolds number in the range of 10 ≤ Re ≤ 300. Incompressible Navier-Stokes and thermal energy equations are solved simultaneously in fluid region by the upwind compact finite difference scheme based on flux-difference splitting in conjunction with artificial compressibility method. In the thick wall, the energy equation is obtained by Laplace equation. A multi-block approach is used to perform parallel computing to reduce the CPU time. Each block is modeled separately by sharing boundary conditions with neighbors. The developed program for modeling was written in FORTRAN language with OpenMP API. The obtained results showed that using of the multi-block parallel computing method is a simple robust scheme with high performance and high-order accurate. Moreover, the obtained results demonstrated that the increment of Reynolds number and obstacle height as well as decrement of horizontal distance between the obstacle and the step improve the heat transfer.

  6. Investigation of third-order closure model of turbulence for the computation of incompressible flows in a channel with a backward-facing step

    NASA Technical Reports Server (NTRS)

    Amano, R. S.; Goel, P.

    1987-01-01

    To predict the diffusion process of the Reynolds stresses in reattaching shear flows, the transport model for the triple-velocity products has been developed and tested for the computation of the flow in a channel with a backward-facing step. Upon comparison of the results of uuv, uvv, and vvv with those obtained by using existing algebraic correlations, it was shown that the present model improved the prediction of the triple-velocity products.

  7. Flow over a rearward facing step

    NASA Technical Reports Server (NTRS)

    Kjelgaard, Scott O.

    1990-01-01

    The characteristics of flow over a rearward facing step is discussed in a paper presented by NASA Lewis Research Center personnel. The objective is to obtain data which will be used for validation of Direct Numerical Simulations being developed at NASA Langley and Ames. Two phases of the work are identified as a study of large scale structures in the flow using hot-wire/cold wire techniques and the development of a statistical data base for using three-component laser velocimetry.

  8. A numerical revisit of backward-facing step flow problem

    NASA Astrophysics Data System (ADS)

    Chiang, T. P.; Sheu, Tony W. H.

    1999-04-01

    In the present study we take a fresh look at a laminar flow evolving into a larger channel through a step configured in a backward-facing format. We conduct steady three-dimensional Navier-Stokes flow analysis in the channel using the step geometry and flow conditions reported by Armaly et al. This allows a direct comparison with the results of physical experiments, thus serving to validate the numerical results computed in the range of 100⩽Re⩽1000. Results show that there is generally excellent agreement between the present results and the experimental data for Re=100 and 389. Fair agreement for Re=1000 is also achieved, except in the streamwise range of 15⩽x⩽25. The main difference stems from the fact that the roof eddy is not extended toward the midspan in the channel with a span width 35 times of the height of the upstream channel. In the present study we also reveal that the flow at the plane of symmetry develops into a two-dimensional-like profile only when the channel width is increased up to 100 times of the upstream step height for the case with Re=800. The present computational results allow the topological features of the flow to be identified using critical point theory. The insight thus gained is useful in revealing a mechanism for the development of an end-wall-induced three-dimensional vortical flow with increasing Reynolds number.

  9. Flow modification over a backward facing step

    NASA Astrophysics Data System (ADS)

    Narveson, Marshall L.

    1990-09-01

    The Naval Postgraduate School (NPS) has undertaken a series of studies on ship air wake tailoring, through the use of deflectors, with the goal of reducing the level of turbulence and the size of the separated zones on the helicopter deck. This reduction will result in a larger engage/disengage envelope, which in turn, will increase the percentage of time that the H-46 and other helicopters can safely operate. This study is the second in the series of NPS to attempt to achieve this goal and considers only the feasibility of tailoring a two-dimensional flow over a backward facing step. Nonporous flat and curved deflectors and porous flat deflectors were mounted in various positions near the edge of the step and the flow patterns recorded using both still and video photography. The deflectors were mounted at varying separations from the step and varying angles to the vertical. It was found that the porous deflectors produced the lowest velocities in the region behind the step, and the nonporous produced the greatest changes in the flow pattern. The results were also compared to the results of the first study that used the PHOENICS computational fluid dynamics program. With one exception, the results differed only by the underprediction of the length of the horizontal flow pattern.

  10. Laminar flow over a backward-facing step

    NASA Astrophysics Data System (ADS)

    Zebib, A.; Homsy, G. M.

    1984-09-01

    The steady, two-dimensional flow of an incompressible fluid over a backward-facing step is computed by a finite difference procedure. The flow depends upon the Reynolds number, Re, based on the inlet flow conditions, and on the dimensionless step height, s. Spatially resolved, accurate solutions are obtained for a range of s for Reynolds numbers as high as 350. The primary flow feature is a steady separated region immediately in back of the step. Additionally, a secondary separated vortex can appear on the top, straight wall of the channel. A region is delineated in the (s,Re) plane where laminar separation occurs on the top surface. It is concluded that there is no flow reversal on the top surface if Re is less than about 200, regardless of the step height s. The occurrence of this secondary vortex is associated with laminar separation of the top boundary layer produced by an adverse pressure gradient along the top of the channel.

  11. 12. DETAIL VIEW OF STEPPED CONCRETE GRAVITY DAM FACE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. DETAIL VIEW OF STEPPED CONCRETE GRAVITY DAM FACE AND ROCK OUTCROPPING, WITH LAKE IN BACKGROUND, SHOWN AT MINIMUM WATER FLOW, LOOKING SOUTHEAST (UPSTREAM) - Van Arsdale Dam, South Fork of Eel River, Ukiah, Mendocino County, CA

  12. CHANNEL EROSION BEHIND FACILITIES 316 AND 362. VIEW FACING NORTH. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CHANNEL EROSION BEHIND FACILITIES 316 AND 362. VIEW FACING NORTH. - U.S. Naval Base, Pearl Harbor, Naval Housing Area Hospital Point, Along First Avenue to west of & along Ford Island Way, Pearl City, Honolulu County, HI

  13. 4. SPILLWAY DRUM GATES AND CHANNEL, LOOKING NORTHEAST (upstream face ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SPILLWAY DRUM GATES AND CHANNEL, LOOKING NORTHEAST (upstream face and Control House in background) - Tieton Dam, Spillway & Drum Gates, South & East side of State Highway 12, Naches, Yakima County, WA

  14. Unsteady separation in a forward-facing step flow

    NASA Astrophysics Data System (ADS)

    Pearson, David; Goulart, Paul; Ganapathisubramani, Bharathram; Imperial College London Team; ETH Zurich Team; University of Southampton Team

    2012-11-01

    The structure and behaviour of the separation region upstream of a forward step is investigated using time-resolved 2D Particle Image Velocimetry. Conditional averages of the flow-field based on the amount of reverse flow present are used to determine the shape and size of the separated flow in relation to the separation point. It is shown that the separation is of `open' form with no reattachment point for approximately 50% of the time. When a reattachment point forms on the step face the separation region can become unstable and expand up and over the step corner. This transfer of mass occurs approximately 10% of the time and is postulated to be caused by large-scale transverse motions at the step face. The conditional averages can be traced backward in time to investigate the upstream flow field prior to such events. It is found that the large scale separations are preceded by a region of low momentum flow convecting toward the step. This momentum deficit creates the conditions under which the separation expands. The size and shape of the momentum deficit, and the timescales over which it acts, is consistent with the large boundary layer structures observed in the literature. EPSRC, through grant no. EP/F056206/1 and EU-FP7 through Grant No. FP7-ICT-2009-4248940.

  15. Theoretical face pressure and drag characteristics of forward-facing steps in supersonic turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Patel, D. K.; Czarnecki, K. R.

    1975-01-01

    A theoretical investigation of the pressure distributions and drag characteristics was made for forward facing steps in turbulent flow at supersonic speeds. An approximate solution technique proposed by Uebelhack has been modified and extended to obtain a more consistent numerical procedure. A comparison of theoretical calculations with experimental data generally indicated good agreement over the experimentally available range of ratios of step height to boundary layer thickness from 7 to 0.05.

  16. Numerical solutions for laminar flow over a backward-facing step

    SciTech Connect

    Szymczak, W.G.; Solomon, J.M.; Berger, A.E.; Bell, J.B.; Osborn, J.E.

    1987-06-01

    In this paper, we present numerical results for steady two-dimensional laminar flow over a rearward facing step. This problem is special in the sense that the use of conservative central differencing of the convective terms does not generate spurious oscillations in the flowfield, even when the cell Reynolds number condition is violated. However, spurious oscillations do appear when considering either the problem of flow over a full step or flow in a smoothly expanding channel. A scheme in which artificial viscosity is added primarily in the flow direction is shown to be more stable than the central difference scheme, without the loss of accuracy associated with certain first order upwind schemes. These computational results are compared to the experimental measurements of Armaly et al., on the rearward facing step problem. The accuracy of these schemes as well as several others appearing in the literature are also tested on two model convection diffusion problems.

  17. The tailored Greens function for a forward facing step

    NASA Astrophysics Data System (ADS)

    Glegg, Stewart

    2013-08-01

    This paper describes the theoretical development of a tailored Greens function for a step based on an application of the Weiner Hopf technique. The results are applied to a boundary layer flow over forward and backward facing steps using the approach developed by P.E. Doak. It is concluded that the sound radiation is a consequence of scattering mechanism that can be modeled from solutions for scattering by parallel semi-infinite plates. At very low frequencies the far-field sound has the characteristics of a streamwise dipole and the sound from turbulent flow in the vicinity of the step scales with the sixth power of the flow velocity. At higher frequencies the directionality is almost omnidirectional and the radiated sound scales as U5. Interference effects become important at high frequencies and the spectrum exhibits a dip at certain angles to the flow. The directionality and spectral characteristics are similar to those measured experimentally.

  18. Computation of turbulent flows over backward-facing step

    NASA Technical Reports Server (NTRS)

    Mansour, N. N.; Kim, J.; Moin, P.

    1983-01-01

    A numerical method for computing incompressible turbulent flows is presented. The method is tested by calculating laminar recirculating flows and is applied in conjunction with a modified Kappa-epsilon model to compute the flow over a backward-facing step. In the laminar regime, the computational results are in good agreement with the experimental data. The turbulent flow study shows that the reattachment length is underpredicted by the standard Kappa-epsilon model. The addition of a term to the standard model that accounts for the effects of rotation on turbulent flow improves the results in the recirculation region and increases the computed reattachment length.

  19. Three-component laser velocimeter surveys of the flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Kjelgaard, Scott O.

    1991-01-01

    A three-component laser velocimeter is used to investigate the flow over a backward-facing step. The backward-facing step had an expansion ratio of 2, a boundary layer height to step height ratio of 0.34 and a Reynolds number based on step height of 19,000. Results from three-component velocimeter surveys of the flow over the backward-facing step are presented with comparisons of the current experiment with previous experiments and computational results. The present results compared well with previous experiments with the exception of the reattachment length. The short reattachment length was due to the short length of the channel downstream. The measurement of the lateral velocity component showed that there is a mean flow in and out of the centerline plane as high as 7 percent of the freestream velocity. However, the shear stresses show no correlation between the lateral fluctuations and the longitudinal and vertical fluctuations, indicating that the flow is 2D in terms of the turbulence quantities.

  20. 66. VIEW OF DELUGE CHANNEL; NORTH FACE OF THEODOLITE SHELTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. VIEW OF DELUGE CHANNEL; NORTH FACE OF THEODOLITE SHELTER (BLDG. 788); TELEVISION CAMERA TOWER; CAMERA TOWER FROM SOUTH END OF LAUNCH DECK - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  1. Turbulent atmospheric flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Kaul, U. K.; Frost, W.

    1976-01-01

    The phenomenon of atmospheric shear layer separation over a man-made structure such as a building (modeled as a backward-facing step) has been analyzed theoretically by (1) solving the two-dimensional equations of motion in the two variables, stream function and vorticity, and by (2) employing an approximate integral technique. Boundary conditions for the undisturbed flow are that of the turbulent atmospheric shear flow over a rough terrain. In the first approach a two-equation model of turbulence was used. In the second approach an approximate technique was utilized in an attempt to describe the details of the flow in the recirculation zone behind the step. The results predict velocity profiles in sufficient detail that the presence of the corner eddy in the region of negative surface pressure gradient is evident. The magnitude of the reversed flow velocity in the recirculation eddy has been found to agree with that found from experiments. Also, a surface eddy viscosity distribution has been an outgrowth of the method which realistically follows the magnitude of the surface pressure gradient distribution as found experimentally.

  2. Single step channeling in glass interior by femtosecond laser

    SciTech Connect

    Kongsuwan, Panjawat; Wang Hongliang; Lawrence Yao, Y.

    2012-07-15

    Channeling inside a transparent material, glass, by femtosecond laser was performed by using a single step process rather than hybrid processes that combine the laser irradiation with an additional tool or step to remove the material. Tightly focusing of a single femtosecond laser pulse using proper optical and laser processing parameters could induce the micro-explosion and could create voids inside transparent materials, and the effects of these parameters on the resultant feature geometry and channel length were studied. Understanding of the channel length variation at different locations from the specimen surface could enhance prediction capability. Taking into account of the laser, material, and lens properties, numerical models were developed to predict the absorption volume shape and size at different focusing depths below the surface of a specimen. These models will also be validated with the variation in feature and channel lengths inside the specimen obtained from the experiments. Spacing between adjacent laser pulses and laser parameters was varied to investigate effects of channel overlapping and its influence on long channel formation.

  3. Laminar backward-facing step flow using the finite element method

    SciTech Connect

    Kornblum, B.; McCallen, R.; Christon, M.A.; Kollmann, W.

    1995-11-01

    Laminar, incompressible flow over a backward-facing step is calculated using a finite element spatial discretization with a piecewise continuous pressure approximation and an explicit time marching algorithm. The time-accurate evolution to steady state is demonstrated for both two-dimensional (2D) and three-dimensional (3D) simulations. This approach is shown to accurately predict the lengths of the recirculation zone on the top wall and at the step for various meshes and domain lengths, for a Reynolds number of 800 based on the average inlet velocity and twice the inlet channel height. The instantaneous and steady-state results are investigated. The steady-state solutions are evaluated by comparison to published numerical and experimental results.

  4. Flow and forced-convection heat transfer over forward-facing double steps (effects of step ratio)

    SciTech Connect

    Shakouchi, Toshihiko; Kajino, Itsuki

    1994-07-01

    The flow and heat transfer over a step (a forward- or backward-facing step) result in complicated flow conditions, such as a shear flow field, flow separation, and generation of vortices, and provide some interesting information that improves understanding of the heat transfer on the surface. This is a very frequent flow, and basic to various kinds of chemical equipment, fluid machinery, combustion furnaces, and IC-packages. Recently, there have been many studies on this flow situation by numerical analysis, measurement of mean and fluctuating velocities within the separation bubble using laser Doppler anemometer, and heat transfer analysis. A flow passage having two steps in tiers (forward- or backward-facing double steps) is also frequent, and it is very important to clarify the effects of each step on the flow and the heat-transfer characteristics. This however, has not yet been investigated. This study presents the results of an experimental investigation on the flow and forced convective heat transfer over forward-facing single and double steps. Measurements of velocity and turbulence intensity, flow visualization, pressure distribution, and heat transfer over forward-facing double steps were carried out for various step ratios, L/a (L: step length, a: step height). From these results, the effects of the step ratio on the flow and heat-transfer characteristics were clarified and the following results were confirmed. Heat-transfer enhancement of a double step is considerable compared with that of a single step or a flat plate.

  5. Acoustic investigation of wall jet over a backward-facing step using a microphone phased array

    NASA Astrophysics Data System (ADS)

    Perschke, Raimund F.; Ramachandran, Rakesh C.; Raman, Ganesh

    2015-02-01

    The acoustic properties of a wall jet over a hard-walled backward-facing step of aspect ratios 6, 3, 2, and 1.5 are studied using a 24-channel microphone phased array at Mach numbers up to M=0.6. The Reynolds number based on inflow velocity and step height assumes values from Reh = 3.0 ×104 to 7.2 ×105. Flow without and with side walls is considered. The experimental setup is open in the wall-normal direction and the expansion ratio is effectively 1. In case of flow through a duct, symmetry of the flow in the spanwise direction is lost downstream of separation at all but the largest aspect ratio as revealed by oil paint flow visualization. Hydrodynamic scattering of turbulence from the trailing edge of the step contributes significantly to the radiated sound. Reflection of acoustic waves from the bottom plate results in a modulation of power spectral densities. Acoustic source localization has been conducted using a 24-channel microphone phased array. Convective mean-flow effects on the apparent source origin have been assessed by placing a loudspeaker underneath a perforated flat plate and evaluating the displacement of the beamforming peak with inflow Mach number. Two source mechanisms are found near the step. One is due to interaction of the turbulent wall jet with the convex edge of the step. Free-stream turbulence sound is found to be peaked downstream of the step. Presence of the side walls increases free-stream sound. Results of the flow visualization are correlated with acoustic source maps. Trailing-edge sound and free-stream turbulence sound can be discriminated using source localization.

  6. Visualization of a locally-forced separated flow over a backward-facing step

    NASA Astrophysics Data System (ADS)

    Chun, K. B.; Sung, H. J.

    A laboratory water channel experiment was made of the separated flow over a backward-facing step. The flow was excited by a sinusoidally oscillating jet issuing from a separation line. The slit was connected to a cavity in which water was forced through a rigid pipe by a scotch-yoke system. The Reynolds number based on the step height (H) was fixed at ReH=1200. The forcing frequency was varied in the range 0.305?StH?0.955 at the forcing amplitude A0=0.3. Time-averaged flow measurements were made by a LDV system, especially in the recirculating region behind the backward-facing step. To characterize the large-scale vortex evolution due to the local forcing, flow visualizations were performed by a dye tracer method with fluorescent ink. The vortex amalgamation process was captured at the effective forcing frequency (StH=0.477) for laminar separation. This vortex merging process enhances flow mixing, which leads to the shortening of the reattachment length.

  7. Effects of an aft facing step on the surface of a laminar flow glider wing

    NASA Technical Reports Server (NTRS)

    Sandlin, Doral R.; Saiki, Neal

    1993-01-01

    A motor glider was used to perform a flight test study on the effects of aft facing steps in a laminar boundary layer. This study focuses on two dimensional aft facing steps oriented spanwise to the flow. The size and location of the aft facing steps were varied in order to determine the critical size that will force premature transition. Transition over a step was found to be primarily a function of Reynolds number based on step height. Both of the step height Reynolds numbers for premature and full transition were determined. A hot film anemometry system was used to detect transition.

  8. Step Bunch Evolution on Vicinal Faces of KDP

    NASA Technical Reports Server (NTRS)

    Booth, N. A.; Chernov, A. A.; Vekilov, P. G.

    2003-01-01

    For in-situ studies of the formation and evolution of step patterns in solution growth, we have assembled an experimental setup based on Michelson interferometry with the growing crystal surface as one of the reflective surfaces. The device allows data collection over a relatively large area (approximately 4 sq. mm) in situ and in real time during growth. The depth resolution is improved over traditional interferometry using phase-shifted images combining by a suitable algorithm. We achieve a depth resolution of approximately 50 Angstroms. Lateral resolution, dependent on the degree of magnification, is around 0.3 to 5 microns. The crystal chosen as a model in this work is potassium dihydrogen phosphate (KDP), the optically non-linear material widely used in frequency doubling applications. Kinetics of KDP crystallization is well studied so that KDP can serve as a benchmark for our investigations. We present quantitative results on the onset, initial stages and development of instabilities in moving step trains on vicinal crystal surfaces at varying supersaturation, flow rate, and flow direction. The kinetics data suggest that at low supersaturations, step bunching is caused by impurity retardation of the steps, while at higher supersaturations, we link the non-linearity during growth to interdependence of the velocity and density of the steps evidenced in independent experiments. The behavior on the surface is very dynamic, small bunches both merge and split from larger bunches as they travel across the facet. We present evidence that despite these dynamics, under steady conditions there exists a limiting value to step bunch height. This height is reached at distances between 600 and 1000 microns from the step source. In our experiments, we observed the retention of this step bunch height limit up to the path of 1500 microns.

  9. Step Bunch Evolution on Vicinal Faces of KDP

    NASA Technical Reports Server (NTRS)

    Booth, N. A.; Chernov, A. A.; Vekilov, P. G.

    2003-01-01

    For in-situ studies of the formation and evolution of step patterns in solution growth, we have assembled an experimental setup based on Michelson interferometry with the growing crystal surface as one of the reflective surfaces. The device allows data collection over a relatively large area (approximately 4 sq. mm) in situ and in real time during growth. The depth resolution is improved over traditional interferometry using phase-shifted images combining by a suitable algorithm. We achieve a depth resolution of approximately 50 Angstroms. Lateral resolution, dependent on the degree of magnification, is around 0.3 to 5 microns. The crystal chosen as a model in this work is potassium dihydrogen phosphate (KDP), the optically non-linear material widely used in frequency doubling applications. Kinetics of KDP crystallization is well studied so that KDP can serve as a benchmark for our investigations. We present quantitative results on the onset, initial stages and development of instabilities in moving step trains on vicinal crystal surfaces at varying supersaturation, flow rate, and flow direction. The kinetics data suggest that at low supersaturations, step bunching is caused by impurity retardation of the steps, while at higher supersaturations, we link the non-linearity during growth to interdependence of the velocity and density of the steps evidenced in independent experiments. The behavior on the surface is very dynamic, small bunches both merge and split from larger bunches as they travel across the facet. We present evidence that despite these dynamics, under steady conditions there exists a limiting value to step bunch height. This height is reached at distances between 600 and 1000 microns from the step source. In our experiments, we observed the retention of this step bunch height limit up to the path of 1500 microns.

  10. Radiation losses of step-tapered channel waveguides.

    PubMed

    Marcuse, D

    1980-11-01

    We compute the radiation losses of a rectangular dielectric waveguide (integrated optics channel waveguide) that is tapered so that its wider cross-sectional dimension increases by roughly a factor of three while its narrow dimension remains constant. As the waveguide widens its refractive index decreases to ensure that the waveguide supports only one guided mode. The taper is approximated by a discontinuous staircase curve. A rectangular waveguide taper of 2-microm thickness, tapering from 3- to 10-microm width through fourteen steps of 0.25-microm height, has a minimum loss (at 0.6328-microm wavelength) of 0.13 dB for a 200-microm taper length.

  11. Performance characteristics of a curved-channel microchannel plate with a curved input face and a plane output face

    NASA Technical Reports Server (NTRS)

    Slater, David C.; Morgan, Jeffrey S.; Timothy, J. Gethyn

    1989-01-01

    The presently performance-evaluated format, in which a high-gain curved-channel microchannel plate (M2MCP) has a spherical concave input face and a plane output face, allows the input face of the MCP (1) to match such curved focal surfaces as that of a Rowland-circle spectrometer mounting, while (2) having a high-resolution plane readout array in proximity focus with the output face. This MCP has been evaluated in a discrete-anode multicathode microchannel array detector system. The saturated modal gain was found to be inversely proportional to the length/diameter ratio of the channels and directly proportional to the applied MCP voltage.

  12. Forward-facing steps induced transition in a subsonic boundary layer

    NASA Astrophysics Data System (ADS)

    Zh, Hui; Fu, Song

    2017-10-01

    A forward-facing step (FFS) immersed in a subsonic boundary layer is studied through a high-order flux reconstruction (FR) method to highlight the flow transition induced by the step. The step height is a third of the local boundary-layer thickness. The Reynolds number based on the step height is 720. Inlet disturbances are introduced giving rise to streamwise vortices upstream of the step. It is observed that these small-scale streamwise structures interact with the step and hairpin vortices are quickly developed after the step leading to flow transition in the boundary layer.

  13. Feed-forward control of the flow over a backward-facing step

    NASA Astrophysics Data System (ADS)

    Juillet, Fabien; Schmid, Peter; McKeon, Beverley

    2012-11-01

    In this study, the control of incoming perturbations in convection-dominated flows is analyzed numerically and experimentally. For this purpose, multiple sensors and actuators are used. First, a model is built from input and output data sequences using a least-squares system identification. Then, a feed-forward Model Predicitive Controller (MPC) is designed. It appears that feed-forward control is particularly relevant when applied to convection-dominated flows. A very general and flexible formulation of the technique is introduced and validated on the flow over a backward-facing step. Although the objective sensors are localized on the walls, the impact of the control is more global and perturbations are also reduced in the middle of the channel. The coupling of system identification together with feed-forward control was found to be a flexible, efficient and experimentally feasible strategy. In particular, the successful numerical control is further supported by experimental results. Support from Ecole Polytechnique and the Partner University Fund (PUF) is gratefully acknowledged.

  14. The dispersion of particles in a separated backward-facing step flow

    NASA Astrophysics Data System (ADS)

    Ruck, B.; Makiola, B.

    1991-05-01

    Flows in technical and natural circuits often involve a particulate phase. To measure the dynamics of suspended, naturally resident or artificially seeded particles in the flow, optical measuring techniques, e.g., laser Doppler anemometry (LDA) can be used advantageously. In this paper the dispersion of particles in a single-sided backward-facing step flow is investigated by LDA. The investigation is of relevance for both, two-phase flow problems in separated flows with the associated particle diameter range of 1-70 μm and the accuracy of LDA with tracer particles of different sizes. The latter is of interest for all LDA applications to measure continuous phase properties, where interest for experimental restraints require tracer diameters in the upper micrometer range, e.g., flame resistant particles for measurements inside reactors, cylinders, etc. For the experiments, a closed-loop wind tunnel with a step expansion was used. Part of this tunnel, the test section, was made of glass. The step had a height H=25 mm (channel height before the step 25 mm, after 50 mm, i.e., an expansion ratio of 2). The width of the channel was 500 mm. The length of the glass test section was chosen as 116 step heights. The wind tunnel, driven by a radial fan, allowed flow velocities up to 50 m/sec which is equivalent to ReH=105. Seeding was performed with particles of well-known size: 1, 15, 30, and 70 μm in diameter. As 1 μm tracers oil droplets were used, whereas for the upper micron range starch particles (density 1.500 kg/m3) were chosen. Starch particles have a spherical shape and are not soluble in cold water. Particle velocities were measured locally using a conventional 1-D LDA system. The measurements deliver the resultant ``flow'' field information stemming from different particle size classes. Thus, the particle behavior in the separated flow field can be resolved. The results show that with increasing particle size, the particle velocity field differs increasingly from

  15. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Ahn, Cheol Hyoun; Hee Kim, So; Gu Yun, Myeong; Koun Cho, Hyung

    2014-12-01

    In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a "step-composition gradient channel." We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (-3.7 V) and good instability characteristics with a reduced threshold voltage shift ( Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm2/V s. We presented a unique active layer of the "step-composition gradient channel" in the oxide TFTs and explained the mechanism of adequate channel design.

  16. Investigation of turbulent separation in a forward-facing step flow

    NASA Astrophysics Data System (ADS)

    Pearson, D. S.; Goulart, P. J.; Ganapathisubramani, B.

    2011-12-01

    The relation between the upstream and downstream regions of separation of the flow over a forward-facing step is investigated using experimental data. High-speed Particle Image Velocimetry (PIV) data is used to show a correlation between the wall shear stress of the oncoming boundary layer and the streamwise location of reverse flow upstream of the step. The time delay associated with the correlation is consistent with average convection velocities in the lower boundary layer. This suggests that appropriate addition of momentum into the boundary layer could be used to control the spatial extent of the separation upstream of the step. In addition, low-speed PIV data is used to show statistical relations between the flow characteristics of the recirculation regions in the vicinity of the step face. It is shown that a slower than average flow velocity above the step face is associated with an increase in the wall-normal extent of upstream reverse flow, an increase in the inclination of the flow above the step and an increase in downstream vorticity.

  17. Assessment of secondary bubble formation on a backward-facing step geometry

    NASA Astrophysics Data System (ADS)

    Juste, G. L.; Fajardo, P.; Guijarro, A.

    2016-07-01

    Flow visualization experiments and numerical simulations were performed on a narrow three-dimensional backward-facing step (BFS) flow with the main objective of characterizing the secondary bubble appearing at the top wall. The BFS has been widely studied because of its geometrical simplicity as well as its ability to reproduce most of the flow features appearing in many applications in which separation occurs. A BFS test rig with an expansion ratio of 2 and two aspect ratios (AR = 4 and AR = 8) was developed. Tests were performed at range of Reynolds numbers ranging from 50 to 1000; visualization experiments provided a qualitative description of secondary bubble and wall-jet flows. Large eddy simulations were carried out with two different codes for validation. Numerical solutions, once validated with experimental data from the literature, were used to acquire a deeper understanding of the experimental visualizations, to characterize the secondary bubble as a function of the flow variables (Reynolds and AR) and to analyze the effect of the secondary bubble on primary reattachment length. Finally, to decouple the sidewall effects due to the non-slip condition and the intrinsic flow three-dimensionality, numerical experiments with free-slip conditions over the sidewalls were computed. The main differences were as follows: When the non-slip condition is used, the secondary bubble appears at a Reynolds number of approximately 200, increases with the Reynolds number, and is limited to a small part of the span. This recirculation zone interacts with the wall-jets and causes the maximum and minimum lengths in the reattachment line of the primary recirculation. Under free slip conditions, the recirculation bubble appears at a higher Reynolds number and covers the entire channel span.

  18. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition

    SciTech Connect

    Ahn, Cheol Hyoun; Hee Kim, So; Gu Yun, Myeong; Koun Cho, Hyung

    2014-12-01

    In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a “step-composition gradient channel.” We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (−3.7 V) and good instability characteristics with a reduced threshold voltage shift (Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm{sup 2}/V s. We presented a unique active layer of the “step-composition gradient channel” in the oxide TFTs and explained the mechanism of adequate channel design.

  19. Laser holographic interferometric measurements of the flow behind a rearward facing step

    NASA Technical Reports Server (NTRS)

    Leonard, Rachel; Chokani, Ndaona

    1993-01-01

    A holographic interferometer has been designed, constructed, and evaluated in an experimental study of the supersonic flow over a rearward facing step. The nominal Mach number at the corner was 2.05 +/- 0.04 and the Reynolds number per inch was 11.9 x 10 exp 6. The holographic interferometric measurements were supplemented by classical measurements of surface pressure, oil flow, and schlieren visualization. The effects of step height and step width were examined. A method to determine the reattachment point from the interferograms was examined and found to be in good agreement with the other measurement techniques. The reattachment point moved closer to the step as the step height was decreased, but its location did not change with varying step width. In addition to providing surface data for the flow over a rearward facing step, this study provides quantitative off-surface density data and Mach number data throughout the flow, obtained from the holographic interferometry measurements, which are suited for code validation.

  20. Analysis of a backward-facing step flow using extended proper orthogonal decomposition

    NASA Astrophysics Data System (ADS)

    Hu, Ruyun; Fu, Song; Liu, Yingzheng

    2016-11-01

    In the present study, an improved delayed detached eddy simulation (IDDES) was conducted for a three-dimensional backward-facing step flow. The spanwise- and time-averaged reattachment location and the characteristic frequency in the relaxation region showed an excellent agreement with the experimental results. The time sequence of the simulated backward-facing step flow in the reattachment region was supplied for the proper orthogonal decomposition (POD) analysis, while that in the region of the whole separation bubble was analyzed using extended proper orthogonal decomposition (EPOD). The EPOD technique was also applied to the region near the step and where vortex paring dominated. Spatial-temporally varying coherent structures were identified, e.g., K-H instability, vortex pairing, vortex shedding and flapping of the shear layer, which were inferred from the dominant POD modes and EPOD modes. We found that the vortex pairing and the flapping of the shear layer had an intimate connection with the shedding process.

  1. Beyond Opponent Coding of Facial Identity: Evidence for an Additional Channel Tuned to the Average Face.

    PubMed

    Jeffery, Linda; Burton, Nichola; Pond, Stephen; Clifford, Colin W G; Rhodes, Gillian

    2017-05-29

    Face identity can be represented in a multidimensional space centered on the average. It has been argued that the average acts as a perceptual norm, with the norm coded implicitly by balanced activation in pairs of channels that respond to opposite extremes of face dimensions (two-channel model). In Experiment 1 we used face identity aftereffects to distinguish this model from a narrow-band multichannel model with no norm. We show that as adaptors become more extreme, aftereffects initially increase sharply and then plateau. Crucially there is no decrease, ruling out narrow-band multichannel coding, but consistent with a two-channel norm-based model. However, these results leave open the possibility that there may be a third channel, tuned explicitly to the norm (three-channel model). In Experiment 2 we show that alternating adaptation widens the range identified as the average whereas adaptation to the average narrows the range, consistent with the three-channel model. Explicit modeling confirmed the three-channel model as the best fit for the combined data from both experiments. However, a two-channel model with decision criteria allowed to vary between adapting conditions, also provided a very good fit. These results support opponent, norm-based coding of face identity with additional explicit coding of the norm. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  2. Large woody debris and flow resistance in step-pool channels, Cascade Range, Washington

    USGS Publications Warehouse

    Curran, Janet H.; Wohl, Ellen E.

    2003-01-01

    Total flow resistance, measured as Darcy-Weisbach f, in 20 step-pool channels with large woody debris (LWD) in Washington, ranged from 5 to 380 during summer low flows. Step risers in the study streams consist of either (1) large and relatively immobile woody debris, bedrock, or roots that form fixed, or “forced,” steps, or (2) smaller and relatively mobile wood or clasts, or a mixture of both, arranged across the channel by the stream. Flow resistance in step-pool channels may be partitioned into grain, form, and spill resistance. Grain resistance is calculated as a function of particle size, and form resistance is calculated as large woody debris drag. Combined, grain and form resistance account for less than 10% of the total flow resistance. We initially assumed that the substantial remaining portion is spill resistance attributable to steps. However, measured step characteristics could not explain between-reach variations in flow resistance. This suggests that other factors may be significant; the coefficient of variation of the hydraulic radius explained 43% of the variation in friction factors between streams, for example. Large woody debris generates form resistance on step treads and spill resistance at step risers. Because the form resistance of step-pool channels is relatively minor compared to spill resistance and because wood in steps accentuates spill resistance by increasing step height, we suggest that wood in step risers influences channel hydraulics more than wood elsewhere in the channel. Hence, the distribution and function, not just abundance, of large woody debris is critical in steep, step-pool channels.

  3. Experimental Study on Flow Field behind Backward-Facing Step Using Detonation-Driven Shock Tunnel

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hwan; Obara, Tetsuro; Ohyagi, Shigeharu; Yoshikawa, Masato

    As a research to develop a SCRAM-jet engine is actively conducted, a necessity to produce a high-enthalpy flow in a laboratory is increasing. In order to develop the SCRAM-jet engine, stabilized combustion in a supersonic flow-field should be attained, in which a duration time of flow is extremely short. Therefore, a mixing process of breathed air and fuel, which is injected into supersonic flow-fields is one of the most important problem. Since, the flow inside SCRAM-jet engine has high-enthalpy, an experimental facility is required to produce such high-enthalpy flow-field. In this study, a detonation-driven shock tunnel was built and was used to produce high-enthalpy flow. At first, a performance of this facility was investigated in order to obtain a Tayloring condition. Furthermore, SCRAM-jet combustor model equipped backward-facing step was installed at test section and flow-fields were visualized using color-schlieren technique. The fuel was injected perpendicular to the flow of Mach number three behind step. The height of backward-facing step and injection pressure were changed to investigate effects of the step on a mixing characteristic between air and fuel. The schlieren photograph and pressure histories show that the fuel was ignited behind step and the height of step is important factor to ignite a fuel in a supersonic flow-field.

  4. Initial steps in the opening of a Shaker potassium channel.

    PubMed

    Hoshi, Toshinori; Armstrong, Clay M

    2012-07-31

    The structural model of a K(V) (K(+)-selective, voltage-gated) channel in the open state is known (Protein Data Bank ID code 2R9R). Each subunit of the channel has four negatively charged residues distributed in the transmembrane segments S1, S2, and S3 that bind to and facilitate the movement within the membrane of the positively charged, voltage-sensing residues of S4. When extrapolated to the closed state, the two outermost negatively charged residues are exposed to extracellular fluid and not bound to S4 residues, all of which have theoretically been driven inward by voltage. If this closed state model is correct, these residues are available to bind external cations. We examined the effects of La(3+) on voltage-gated Shaker K(+) channels. Addition of the trivalent cation La(3+) (50 μM) extracellularly markedly prolongs the lag that precedes channel opening and slows the subsequent rise of K(+) current (I(K)) at all voltages. Decay kinetics of I(K) at negative voltages are unaltered. Gating current (I(g)) recorded from a nonconducting mutant shows that La(3+) reduces the initial amplitude of I(g) nearly twofold. We postulate that, in the resting state, La(3+) binds to the unoccupied, outermost negative residues, hindering outward S4 motion, thus increasing the lag on activation and slowing the rise of I(K). In the activated state, La(3+) is displaced by outward movement of arginine residues in S4; La(3+), therefore, is not present to affect channel closing. The results give strong support to the closed state model of the K(V) channel and a clear explanation of the effect of multivalent cations on cellular excitability.

  5. Trajectory measurements of a wall jet impinging onto a forward facing step entering a cross-flow.

    PubMed

    Langer, D C; Fleck, B A; Wilson, D J

    2010-04-15

    This study examines a horizontal wall jet impinging onto a forward facing step in a cross-flow. Planar laser induced fluorescence (PLIF) experiments in a water channel indicate that the wall-jet flow after impinging onto the step, becomes a vertical jet with an elliptical cross section. Experiments indicate that the jet trajectory scales with the perimeter of the elliptical jet issuing vertically into the cross-flow. The trajectory consists of three regions: the near-field region which is well described by a power law with an exponent of 1/2, the mid-field region where the jet is fully bent over which is described by a power law with an exponent of 1/3, and a far-field region where the jet is dominated by the cross-flow. This paper provides a prediction of the plume behaviour based on the geometric and initial conditions of the jet (diameter, step height, distance from jet to step, and velocity ratio) alone. The Briggs entrainment model for a round jet was also used to predict the trajectories of the jet in the cross-flow. It was found that the entrainment coefficients, alpha and beta, for the elliptical jet case had average values of 0.15 and 0.58 respectively. 2009 Elsevier B.V. All rights reserved.

  6. Surface flow visualisation over forward facing steps with varying yaw angle

    NASA Astrophysics Data System (ADS)

    Rowcroft, J.; Burton, D.; Blackburn, H. M.; Sheridan, J.

    2014-12-01

    Many Australian wind farms are located near escarpments and cliffs where flow separation occurs. An absence of literature addressing the effect of wind direction over cliffs have motivated surface shear stress visualisations on forward facing steps at yaw angles between 0° and 50°. These visualisations have been conducted in the Monash University 450 kW wind tunnel. Mean reattachment lengths were measured and shown to vary as a function of the boundary layer thickness to step height ratio and the yaw angle. Vortices shed off the crest of the step induced surface shear stresses on the top surface of the step. The orientation of these shear stresses varied linearly with the yaw angle. Three-dimensional structures of different forms were also observed. At zero yaw angle the flow converged at points along the crest. At high yaw angles distinct sections of misaligned flow were observed downstream of the reattachment line, indicating a spatial periodicity in shedding.

  7. Analysis of neutrally stable atmospheric flow over a two-dimensional forward facing step

    NASA Technical Reports Server (NTRS)

    Bitte, J.; Frost, W.

    1976-01-01

    A mathematical model describing ground-wind induced flow fields around surface obstructions such as buildings, bridges or other man-made structures is presented. The Navier-Stokes equations with a two-equation turbulence model are used to analyze the flow over a two-dimensional forward facing step. A study of the assumed logarithmic approach velocity profile shows that an increase of surface roughness produces a rise to higher turbulence levels in the shear layer originating from the step corner. This rise leads to higher Reynolds stress and to faster reattachment of the separated flow.

  8. Hydraulic characteristics of debris flows in a drainage channel with stepped dissipater

    NASA Astrophysics Data System (ADS)

    Chen, Huayong; Chen, Xiaoqing; Zhao, Wanyu

    2017-04-01

    Sichuan-Tibet railway started from Chengdu, via Pujiang, Ya'an, Kangding, Litang, Zuogong, Bomi, nyingchi, and lhasa, which covers a distance of 1,629 km. The Sichuan-Tibet railway cuts through the alpine region that has the feature of large elevation difference, active tectonics, and obvious space differentiation. Debris flows with high density, low viscosity, and high speed are one of the most common geo-hazards in these regions. A new type of drainage channel with stepped dissipater was proposed to apply to mitigate the debris flow disaster in the alpine region. The debris flow patterns, debris flow velocity, energy dissipation along the drainage channel were analyzed under different structures of the drainage channels based on the experiments. The roughness coefficient calculated by the Manning formula was also investigated along the flow depth for both rectangular channel and the channel with stepped dissipater. The results indicated that compared with the traditional rectangular drainage channel, the channel with stepped dissipater has more efficiency to decrease the flow velocity, Reduce the abrasion along drainage channel, and improve the energy dissipation rate due to the Intense collision, friction between debris flows and the solid boundary. The maximum energy dissipation rate reaches approximately 61%. Based on the theory of particle projectile, the relation between the step length and the debris flow velocity, step height was proposed..

  9. Direct numerical simulation of turbulent flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Le, Hung; Moin, Parviz

    1993-01-01

    The objectives of this study are as follows: (1) to conduct a direct numerical simulation of turbulent backward facing step flow using inflow and outflow conditions; and (2) to provide data in the form of Reynolds stress budgets for Reynolds averaged modeling. The report presents the basic statistical data and comparisons with the concurrent experiments of Jovic and Driver and budgets of turbulent kinetic energy.

  10. Aerodynamic Impact of an Aft-Facing Slat-Step on High Re Airfoils

    NASA Astrophysics Data System (ADS)

    Kibble, Geoffrey; Petrin, Chris; Jacob, Jamey; Elbing, Brian; Ireland, Peter; Black, Buddy

    2016-11-01

    Typically, the initial aerodynamic design and subsequent testing and simulation of an aircraft wing assumes an ideal wing surface without imperfections. In reality, however the surface of an in-service aircraft wing rarely matches the surface characteristics of the test wings used during the conceptual design phase and certification process. This disconnect is usually deemed negligible or overlooked entirely. Specifically, many aircraft incorporate a leading edge slat; however, the mating between the slat and the top surface of the wing is not perfectly flush and creates a small aft-facing step behind the slat. In some cases, the slat can create a step as large as one millimeter tall, which is entirely submerged within the boundary layer. This abrupt change in geometry creates a span-wise vortex behind the step and in transonic flow causes a shock to form near the leading edge. This study investigates both experimentally and computationally the implications of an aft-facing slat-step on an aircraft wing and is compared to the ideal wing surface for subsonic and transonic flow conditions. The results of this study are useful for design of flow control modifications for aircraft currently in service and important for improving the next generation of aircraft wings.

  11. Shock wave Boundary layer interaction in supersonic flow over a forward-facing step

    NASA Astrophysics Data System (ADS)

    Narayan M., Jayaprakash; Govardhan, Raghuraman

    2014-11-01

    Shock wave boundary layer interactions (SWBLI) are known to result in low-frequency large-scale shock oscillations, the origin of which has been a subject of debate. Motivated by this debate, we study in the present work, the SWBLI in supersonic flow over a Forward-Facing Step (FFS) at a Mach number of 2.5. The FFS configuration, which consists of a 90 degree step of height h, may be thought of as an extreme case of the compression ramp geometry, with the main geometrical parameter here being (h / δ) (δ is the boundary layer thickness). This configuration is less studied and has some inherent advantages for experimentally studying SWBLI as the size of the separation bubble is large. In the present experimental study, we use high-speed schlieren and PIV measurements to help understand the features of SWBLI in the forward-facing step case. PIV measurements show a clear time-averaged separation bubble ahead of the step, with very large variations of the separation bubble in time. From instantaneous PIV velocity fields, a number of features are extracted including size of the separation bubble and the shock location, to comment on their variations in time, and to determine correlation coefficients.

  12. Active flow control over a backward-facing step using plasma actuation

    NASA Astrophysics Data System (ADS)

    Ruisi, R.; Zare-Behtash, H.; Kontis, K.; Erfani, R.

    2016-09-01

    Due to the more stringent aviation regulations on fuel consumption and noise reduction, the interest for smaller and mechanically less complex devices for flow separation control has increased. Plasma actuators are currently among the most studied typology of devices for active flow control purposes due to their small size and lightweight. In this study, a single dielectric barrier discharge (SDBD) actuator is used on a backward-facing step to assess its effects on the separated turbulent shear layer and its reattachment location. A range of actuating modulation frequencies, related to the natural frequencies of shear layer instability (flapping) and vortex shedding instability, are examined. The particle image velocimetry technique is used to analyse the flow over the step and the reattachment location. The bulk-flow experiments show negligible effects both on the shear layer and on the reattachment location for every frequency considered, and the actuator is not able to induce a sufficient velocity increase at the step separation point.

  13. Experimental study of combustion in a turbulent free shear layer formed at a rearward facing step

    NASA Technical Reports Server (NTRS)

    Pitz, R. W.; Daily, J. W.

    1981-01-01

    A premixed propane-air flame is stabilized in a turbulent free shear layer formed at a rearward facing step. The mean and rms averages of the turbulent velocity flow field are determined by LDV for both reacting (equivalence ratio 0.57) and nonreacting flows (Reynolds number 15,000-37,000 based on step height). The effect of combustion is to shift the layer toward the recirculation zone and reduce the flame spread. For reacting flow, the growth rate is unchanged except very near the step. The probability density function of the velocity is bimodial near the origin of the reacting layer and single-peaked but often skewed elsewhere. Large-scale structures dominate the reacting shear layer. Measurements of their passing frequency from LDV are consistent with high-speed Schlieren movies of the reacting layer and indicate that the coalescence rate of the eddies in the shear layer is reduced by combustion.

  14. Numerical predictions of residence times behind a rearward facing step with transverse injection

    NASA Technical Reports Server (NTRS)

    Rogers, R. C.; Weidner, E. H.

    1983-01-01

    A numerical investigation of the two-dimensional recirculation zone formed between a rear-ward facing step and a transverse hydrogen jet in a supersonic flow is presented. Calculations were made using an elliptic flow computer code with a time-relaxation finite difference integration algorithm. Cases were examined for jet static pressures between 2 and 5 times mainstream with jets located 3 to 7 step heights downstream of the step. Nominal mainstream flow conditions were Mach 2.4 air at 1 atm pressure and 1000K (1800R) static temperature. Results in the form of mean properties in the recirculation zone and residence time are presented. Calculations of the decay of hydrogen mass from the steady state are presented for selected cases. The combustion potential for each case is assessed by comparison of computed conditions in the recirculation zone with the results from a well-stirred reactor theory.

  15. Experimental and Numerical Studies of Flows over Forward Facing Steps in Pressure Gradients

    NASA Astrophysics Data System (ADS)

    Iftekhar, Hassan

    This thesis reports experimental and numerical studies of the effects of adverse pressure gradients (APG) and Reynolds numbers on flows over forward facing steps (FFS). For the experimental work, particle image velocimetry was used to conduct velocity measurements at several locations downstream of the FFS. Proper orthogonal decomposition and two-point correlation were applied to the experimental data to study the large scale structures. For the numerical analysis, turbulence models in ANSYS Fluent were used to study the reattachment length XL for blockage ratios from 5.8% to 29.5% and step inclination angles from 22.5° to 135°. The experimental results show that XL increases with the increase in Reynolds number without APG, but remains nearly constant for increasing APG. The CFD results show that as the step angle is increased, XL decreased. Furthermore, increasing the blockage at constant Reynolds number, the XL values decrease.

  16. Effect of initial conditions on turbulent reattachment downstream of a backward-facing step

    NASA Technical Reports Server (NTRS)

    Westphal, R. V.; Johnston, J. P.

    1984-01-01

    The reattachment of a fully turbulent, two-dimentional shear layer downstream of a backward-facing step has been studied experimentally. The work examines the effect of variations in inlet conditions on the process of reattachment. A series of experiments was conducted in a low-speed wind tunnel using specialized instrumentation suited to the highly turbulent reversing flow near reattachment. Accurate characterization of the time-mean features of the reattaching flows was possible. Assuming linear scaling normalized on distance from reattachment, distributions of normalized pressure coefficient and forward flow fraction, and time-averaged skin friction coefficient appear universal for two-dimensional reattachment, independent of initial conditions and step height, for given duct geometry (area ratio) and for high step-height Reyolds numbers with thin separating boundary layers. The results suggest universal flow structure in the reattachment zone.

  17. Numerical predictions of residence times behind a rearward facing step with transverse injection

    NASA Technical Reports Server (NTRS)

    Rogers, R. C.; Weidner, E. H.

    1983-01-01

    A numerical investigation of the two-dimensional recirculation zone formed between a rearward facing step and a transverse hydrogen jet in a supersonic flow is presented. Calculations were made using an elliptic flow computer code with a time-relaxation finite difference integration algorithm. Cases were examined for jet static pressures between 2 and 5 times mainstream with jets located 3 to 7 step heights downstream of the step. Nominal mainstream flow conditions were Mach 2.4 air at 1 atm pressure and 1000 K (1800 R) static temperature. Results in the form of mean properties in the recirculation zone and residence time are presented. Calculations of the decay of hydrogen mass from the steady state are presented for selected cases. The combustion potential for each case is assessed by comparison of computed conditions in the recirculation zone with the results from a well-stirred reactor theory.

  18. Starting flow and heat transfer downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Tsou, F. K.; Chen, Shih-Jiun; Aung, Win

    1991-08-01

    The starting of heat transfer downstream of a backward-facing step was studied experimentally using a Ludwieg tube wind tunnel to produce an incompressible flow with an accelerating period of 7 ms and a steady-state period of 12 ms. The flow and heat transfer history were measured by hot-wire anemometry and heat flux gauges, respectively. The onset of transition in the free shear layer indicates that the disturbance originates from the top corner of the step and then propagates to the free stream. The velocity and turbulence profiles in the free shear layer reach steady-state values after the leading edge disturbance traverses to the measurement locations. Heat flux history data suggest the transformation of the flow from laminar to transitional and finally to turbulent flow in regions upstream and far downstream of the step.

  19. LDA measurements in a Mach 2 flow over a rearward facing step with staged transverse injection

    NASA Technical Reports Server (NTRS)

    Wang, J.-A.; Dancey, C. L.

    1992-01-01

    Measurements of the mean velocity field and selected turbulence statistics have been obtained via 2D LDA in a Mach 2 flow over a rearward facing step with downstream transverse injection. Axial mean velocity profiles, profiles of the axial and normal RMS levels, and the correlation coefficient between the axial and normal fluctuating components are presented for locations upstream of the step. These data, through comparison with other reported measurements in zero pressure gradient compressible boundary layers indicate that the boundary layers upstream of the step are consistent with 'quasi-equilibrium' turbulent boundary layers with the adiabatic wall boundary condition. Mean velocity field measurements on the symmetry plane of the tunnel are compared to laser induced iodine fluorescence measurements reported in the literature and obtained in the same facility. This comparison demonstrates the quality of the present LDA data set and shows that particle lag is not significant in the LDA measurements despite the complex nature of the downstream flow.

  20. 2-Step Maximum Likelihood Channel Estimation for Multicode DS-CDMA with Frequency-Domain Equalization

    NASA Astrophysics Data System (ADS)

    Kojima, Yohei; Takeda, Kazuaki; Adachi, Fumiyuki

    Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can provide better downlink bit error rate (BER) performance of direct sequence code division multiple access (DS-CDMA) than the conventional rake combining in a frequency-selective fading channel. FDE requires accurate channel estimation. In this paper, we propose a new 2-step maximum likelihood channel estimation (MLCE) for DS-CDMA with FDE in a very slow frequency-selective fading environment. The 1st step uses the conventional pilot-assisted MMSE-CE and the 2nd step carries out the MLCE using decision feedback from the 1st step. The BER performance improvement achieved by 2-step MLCE over pilot assisted MMSE-CE is confirmed by computer simulation.

  1. Mixed Convection in Turbulent-Separated Backward-Facing Step Flows.

    NASA Astrophysics Data System (ADS)

    Lin, Jen-Tai

    Mixed convective heat transfer results for two -dimensional laminar/turbulent flow in a duct with a backward -facing step are reported. The two walls forming the duct are maintained at uniform but different temperatures. The straight wall is maintained at the inlet air temperature, while the downstream section of the stepped wall is heated to a higher temperature. This study focuses on a backward -facing step geometry with an expansion ratio of two. The present laminar study examines a wide range of inlet flow and wall temperature conditions to cover the domain from buoyancy-assisting mixed convective flow, pure forced convective flow, buoyancy-opposing mixed convective flow to the inlet starved convective flow. Turbulent mixed convective flow is numerically simulated by using a modified k - epsilon model. For the buoyancy-assisting laminar flow, the buoyancy force reduces the pressure drop across the duct along with the reattachment length and increases the heat transfer rate. The reverse of previous trend applies for the buoyancy-opposing flow condition. A larger buoyancy force in buoyancy-assisting turbulent flow will decrease turbulent kinetic energy, increase the dissipation rate of turbulent kinetic energy, thus causing reattachment length to increase and the heat transfer rate to decrease. The numerical predictions are compared very favorably with existing, but limited, experimental and numerical data.

  2. Pressure-velocity correlations in a flow upstream of a forward-facing step

    NASA Astrophysics Data System (ADS)

    Pearson, David; Goulart, Paul; Ganapathisubramani, Bharathram; Imperial College Flow Control Group Team

    2011-11-01

    The 2-dimensional velocity field upstream of a forward step was determined experimentally using Particle Image Velocimetry. A total of 4 seconds of data was acquired at 8000 Hz . The flow velocity was 10ms-1 with an Reh of 20000, where h = 0 . 03 m is the step height. The boundary layer thickness relative to step height was δ / h = 1 . 6 . The upstream surface pressure fluctuations were simultaneously measured using an array of 9 microphones embedded in tunnel floor. These pressure fluctuations are shown to have a direct linear correlation to the velocity perturbations. The correlation has a maximum of approximately 0.3 at upstream stations x / h > 2 and reduces toward background noise levels as the flow approaches separation at 0 . 5 < x / h < 1 . 5 . It is also shown that large pressure fluctuations upstream correlate to changes in shape and structure of the separation region at the step. This data demonstrates the ability to estimate some flow characteristics at the step face from the oncoming boundary layer, through the use of pressure measurements at the wall.

  3. Direct Numerical Simulation of Air Layer Drag Reduction over a Backward-facing Step

    NASA Astrophysics Data System (ADS)

    Kim, Dokyun; Moin, Parviz

    2010-11-01

    Direct Numerical Simulation (DNS) of two-phase flow is performed to investigate the air layer drag reduction (ALDR) phenomenon in turbulent flow over a backward-facing step. In their experimental study, Elbing et al. (JFM, 2008) have observed a stable air layer on an entire flat plate if air is injected beyond the critical air-flow rate. In the present study, air is injected at the step on the wall into turbulent water flow for ALDR. The Reynolds and Weber numbers based on the water properties and step height are 22,800 and 560, respectively. An inlet section length before the step is 3h and the post expansion length is 30h, where h is the step height. The total number of grid points is about 271 million for DNS. The level set method is used to track the phase interface and the structured-mesh finite volume solver is used with an efficient algorithm for two-phase DNS. Two cases with different air-flow rates are performed to investigate the mechanism and stability of air layer. For high air-flow rate, the stable air layer is formed on the plate and more than 90% drag reduction is obtained. In the case of low air-flow rate, the air layer breaks up and ALDR is not achieved. The parameters governing the stability of air layer from the numerical simulations is also consistent with the results of stability analysis.

  4. Effects of Forward- and Backward-Facing Steps on the Crossflow Receptivity and Stability in Supersonic Boundary Layers

    NASA Technical Reports Server (NTRS)

    Balakumar, P.; King, Rudolph A.; Eppink, Jenna L.

    2014-01-01

    The effects of forward- and backward-facing steps on the receptivity and stability of three-dimensional supersonic boundary layers over a swept wing with a blunt leading edge are numerically investigated for a freestream Mach number of 3 and a sweep angle of 30 degrees. The flow fields are obtained by solving the full Navier-Stokes equations. The evolution of instability waves generated by surface roughness is simulated with and without the forward- and backward-facing steps. The separation bubble lengths are about 5-10 step heights for the forward-facing step and are about 10 for the backward-facing step. The linear stability calculations show very strong instability in the separated region with a large frequency domain. The simulation results show that the presence of backward-facing steps decreases the amplitude of the stationary crossflow vortices with longer spanwise wavelengths by about fifty percent and the presence of forward-facing steps does not modify the amplitudes noticeably across the steps. The waves with the shorter wavelengths grow substantially downstream of the step in agreement with the linear stability prediction.

  5. Laminar CuO-water nano-fluid flow and heat transfer in a backward-facing step with and without obstacle

    NASA Astrophysics Data System (ADS)

    Togun, Hussein

    2016-03-01

    This paper presents a numerical investigate on CuO-water nano-fluid and heat transfer in a backward-facing step with and without obstacle. The range of Reynolds number varied from 75 to 225 with volume fraction on CuO nanoparticles varied from 1 to 4 % at constant heat flux was investigated. Continuity, momentum, and energy equations with finite volume method in two dimensions were employed. Four different configurations of backward-facing step (without obstacle, with obstacle of 1.5 mm, with obstacle of 3 mm, with obstacle of 4.5 mm) were considered to find the best thermal performance. The results show that the maximum augmentation in heat transfer was about 22 % for backward-facing step with obstacle of 4.5 mm and using CuO nanoparticles at Reynolds number of 225 compared with backward-facing step without obstacle. It is also observed that increase in size of recirculation region with increase of height obstacle on the channel wall has remarkable effect on thermal performance. The results also found that increases in Reynolds number, height obstacle, and volume fractions of CuO nanoparticles lead to increase of pressure drop.

  6. Film thickness measurement for spiral groove and Rayleigh step lift pad self-acting face seals

    NASA Technical Reports Server (NTRS)

    Dirusso, E.

    1982-01-01

    One Rayleigh step lift pad and three spiral groove self-acting face seal configurations were tested to measure film thickness and frictional torque as a function of shaft speed. The seals were tested at a constant face load of 73 N (16.4 lb) with ambient air at room temperature and atmospheric pressure as the fluid medium. The test speed range was from 7000 to 17,000 rpm. The measured film thickness was compared with theoretical data from mathematical models. The mathematical models overpredicted the measured film thickness at the lower speeds of the test speed range and underpredicted the measured film thickness at the higher speeds of the test speed range.

  7. Numerical simulation of turbulent heat transfer past a backward-facing step: 2D/3D RANS versus IDDES solutions

    NASA Astrophysics Data System (ADS)

    Smirnov, E. M.; Smirnovsky, A. A.; Schur, N. A.; Zaitsev, D. K.; Smirnov, P. E.

    2016-09-01

    The contribution covers results of numerical study of air flow and heat transfer past a backward-facing step at the Reynolds number of 28,000. The numerical simulation was carried out under conditions of the experiments of Vogel&Eaton (1985), where nominally 2D fluid dynamics and heat transfer in a channel with expansion ratio of 1.25 was investigated. Two approaches were used for turbulence modelling. First, the Menter SST turbulence model was used to perform refined 2D and 3D RANS steady-state computations. The 3D analysis was undertaken to evaluate effects of boundary layers developing on the sidewalls of the experimental channel. Then, 3D time-dependent computations were carried out using the vortex-resolving IDDES method and applying the spanwise-periodicity conditions. Comparative computations were performed using an in-house finite-volume code SINF/Flag-S and the ANSYS Fluent. The codes produced practically identical RANS solutions, showing in particular a difference of 4% in the central-line peak Stanton number calculated in 2D and 3D cases. The IDDES results obtained with two codes are in a satisfactory agreement. Comparing with the experimental data, the IDDES produces the best agreement for the wall friction, whereas the RANS solutions show superiority in predictions of the local Stanton number distribution.

  8. Solutions of turbulent backward-facing step flow with heat transfer using the finite volume method

    SciTech Connect

    Horstman, R.H.; Cochran, R.J.; Emergy, A.F.

    1995-12-31

    The heated turbulent flow over a backward-facing step is numerically solved using the commercial computational fluid dynamics program FLUENT. The methods used here consist of the default power-law upwinding scheme, default multigrid equation solution method and a standard k-{var_epsilon} turbulence model with wall functions. A total of four separate cases are reported. The four cases consist of combinations of partially and fully developed flow at the inlet with uniform or developed temperature profiles. Three mesh refinements are reported for each flow.

  9. Stability of compressible boundary layers over a smooth backward-facing step

    NASA Technical Reports Server (NTRS)

    Ragab, S. A.; Nayfeh, A. H.; Krishna, R. C.

    1990-01-01

    An investigation is conducted into the determination of the credibility of interacting boundary layers in predicting compressible subsonic flows over smooth surface imperfections. The case of smooth backward-facing steps is considered. The predicted mean flows are compared with those obtained using a Navier-Stokes solver. Moreover, the linear 2-D compressible stability characteristics of both mean flows are compared. The results show that the interacting boundary-layer formulation produces accurate mean flows that yield accurate linear stability characteristics, such as growth rates and amplification factors.

  10. Applicability of the independence principle to subsonic turbulent flow over a swept rearward-facing step

    NASA Technical Reports Server (NTRS)

    Selby, G. V.

    1983-01-01

    Prandtl (1946) has concluded that for yawed laminar incompressible flows the streamwise flow is independent of the spanwise flow. However, Ashkenas and Riddell (1955) have reported that for turbulent flow the 'independence principle' does not apply to yawed flat plates. On the other hand, it was also found that this principle may be applicable to many turbulent flows. As the sweep angle is increased, a sweep angle is reached which defines the interval over which the 'independence principle' is valid. The results obtained in the present investigation indicate the magnitude of the critical angle for subsonic turbulent flow over a swept rearward-facing step.

  11. Stability of compressible boundary layers over a smooth backward-facing step

    NASA Technical Reports Server (NTRS)

    Ragab, S. A.; Nayfeh, A. H.; Krishna, R. C.

    1989-01-01

    An investigation is conducted into the determination of the credibility of interacting boundary layers in predicting compressible subsonic flows over smooth surface imperfections. The case of smooth backward-facing steps is considered. The predicted mean flows are compared with those obtained using a Navier-Stokes solver. Moreover, the linear 2-D compressible stability characteristics of both mean flows are compared. The results show that the interacting boundary-layer formulation produces accurate mean flows that yield accurate linear stability characteristics, such as growth rates and amplification factors.

  12. Stratified flow over a backward-facing step: hybrid solution by integral transforms

    NASA Astrophysics Data System (ADS)

    Ramos, R.; Perez Guerrero, J. S.; Cotta, R. M.

    2001-01-01

    The generalized integral transform technique (GITT) is employed in the hybrid numerical-analytical solution of the stratified backward-facing step flow problem, with automatic global accuracy control towards a user-prescribed accuracy target. The present paper is aimed at extending the available database on benchmark results in heat and fluid flow, which were progressively obtained through integral transforms, for the co-validation of more flexible fully discrete approaches. Numerical results are presented for the situations more frequently encountered in the literature Copyright

  13. Least-squares finite element solutions for three-dimensional backward-facing step flow

    NASA Technical Reports Server (NTRS)

    Jiang, Bo-Nan; Hou, Lin-Jun; Lin, Tsung-Liang

    1993-01-01

    Comprehensive numerical solutions of the steady state incompressible viscous flow over a three-dimensional backward-facing step up to Re equals 800 are presented. The results are obtained by the least-squares finite element method (LSFEM) which is based on the velocity-pressure-vorticity formulation. The computed model is of the same size as that of Armaly's experiment. Three-dimensional phenomena are observed even at low Reynolds number. The calculated values of the primary reattachment length are in good agreement with experimental results.

  14. Applicability of the independence principle to subsonic turbulent flow over a swept rearward-facing step

    NASA Technical Reports Server (NTRS)

    Selby, G. V.

    1983-01-01

    Prandtl (1946) has concluded that for yawed laminar incompressible flows the streamwise flow is independent of the spanwise flow. However, Ashkenas and Riddell (1955) have reported that for turbulent flow the 'independence principle' does not apply to yawed flat plates. On the other hand, it was also found that this principle may be applicable to many turbulent flows. As the sweep angle is increased, a sweep angle is reached which defines the interval over which the 'independence principle' is valid. The results obtained in the present investigation indicate the magnitude of the critical angle for subsonic turbulent flow over a swept rearward-facing step.

  15. Main laws of the influence of a flow angularity on the parameters of pressure fluctuation fields in front of a forward-facing step and behind a backward-facing step

    NASA Astrophysics Data System (ADS)

    Bibko, V. N.; Golubev, A. Yu.

    2014-09-01

    Experimental investigations of the influence of flow angularity on the properties of pressure fluctuation fields in front of a forward-facing step and behind a backward-facing step are performed. These fields are shown to be inhomogeneous and three-dimensional in the case of flow angularity. It is shown that the pressure fluctuation field is characterized by the lowest scale of the inhomogeneity along the orthogonal line to the step edge, the highest degree of correlation, and the presence of convective field properties in the direction collinear to the flow. The influence of the flow angularity on the scale of the inhomogeneity and normalized mutual spectrum of pressure fluctuation fields in front of a forward-facing step and behind a backward-facing step is reveled to a lesser degree than its influence on the spectral density. Refinement of the empirical model of the pressure fluctuation field in front of a forward-facing step and behind a backward-facing step is proposed taking into account the three-dimensionality of the field.

  16. Backward-facing step measurements at low Reynolds number, Re(sub h)=5000

    NASA Technical Reports Server (NTRS)

    Jovic, Srba; Driver, David M.

    1994-01-01

    An experimental study of the flow over a backward-facing step at low Reynolds number was performed for the purpose of validating a direct numerical simulation (DNS) which was performed by the Stanford/NASA Center for Turbulence Research. Previous experimental data on back step flows were conducted at Reynolds numbers and/or expansion ratios which were significantly different from that of the DNS. The geometry of the experiment and the simulation were duplicated precisely, in an effort to perform a rigorous validation of the DNS. The Reynolds number used in the DNS was Re(sub h)=5100 based on step height, h. This was the maximum possible Reynolds number that could be economically simulated. The boundary layer thickness, d, was approximately 1.0 h in the simulation and the expansion ratio was 1.2. The Reynolds number based on the momentum thickness, Re(sub theta), upstream of the step was 610. All of these parameters were matched experimentally. Experimental results are presented in the form of tables, graphs and a floppy disk (for easy access to the data). An LDV instrument was used to measure mean velocity components and three Reynolds stresses components. In addition, surface pressure and skin friction coefficients were measured. LDV measurements were acquired in a measuring domain which included the recirculating flow region.

  17. Stepped Care Versus Direct Face-to-Face Cognitive Behavior Therapy for Social Anxiety Disorder and Panic Disorder: A Randomized Effectiveness Trial.

    PubMed

    Nordgreen, Tine; Haug, Thomas; Öst, Lars-Göran; Andersson, Gerhard; Carlbring, Per; Kvale, Gerd; Tangen, Tone; Heiervang, Einar; Havik, Odd E

    2016-03-01

    The aim of this study was to assess the effectiveness of a cognitive behavioral therapy (CBT) stepped care model (psychoeducation, guided Internet treatment, and face-to-face CBT) compared with direct face-to-face (FtF) CBT. Patients with panic disorder or social anxiety disorder were randomized to either stepped care (n=85) or direct FtF CBT (n=88). Recovery was defined as meeting two of the following three criteria: loss of diagnosis, below cut-off for self-reported symptoms, and functional improvement. No significant differences in intention-to-treat recovery rates were identified between stepped care (40.0%) and direct FtF CBT (43.2%). The majority of the patients who recovered in the stepped care did so at the less therapist-demanding steps (26/34, 76.5%). Moderate to large within-groups effect sizes were identified at posttreatment and 1-year follow-up. The attrition rates were high: 41.2% in the stepped care condition and 27.3% in the direct FtF CBT condition. These findings indicate that the outcome of a stepped care model for anxiety disorders is comparable to that of direct FtF CBT. The rates of improvement at the two less therapist-demanding steps indicate that stepped care models might be useful for increasing patients' access to evidence-based psychological treatments for anxiety disorders. However, attrition in the stepped care condition was high, and research regarding the factors that can improve adherence should be prioritized. Copyright © 2015. Published by Elsevier Ltd.

  18. Bedload transport rates in a step-pool channel at near-bankfull flows

    Treesearch

    Daniel A. Marion

    2001-01-01

    This paper examines unit bedload transport rates (BTRs) at near-bankfull flows within a small step-pool channel in the Ouachita Mountains of central Arkansas. For this study, five runoff events with peak discharges between 0.25 and 1.34 cms (1.0- to 1.6-yr recurrence intervals) were produced in a natural channel using a streamflow simulation system. BTRs range from...

  19. The impact of equivalence ratio oscillations on combustion dynamics in a backward-facing step combustor

    SciTech Connect

    Murat Altay, H.; Speth, Raymond L.; Hudgins, Duane E.; Ghoniem, Ahmed F.

    2009-11-15

    The combustion dynamics of propane-air flames are investigated in an atmospheric pressure, atmospheric inlet temperature, lean, premixed backward-facing step combustor. We modify the location of the fuel injector to examine the impact of equivalence ratio oscillations arriving at the flame on the combustion dynamics. Simultaneous pressure, velocity, heat-release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When the fuel is injected far upstream from the step, the equivalence ratio arriving at the flame is steady and the combustion dynamics are controlled only by flame-vortex interactions. In this case, different dynamic regimes are observed depending on the operating parameters. When the fuel is injected close to the step, the equivalence ratio arriving at the flame exhibits oscillations. In the presence of equivalence ratio oscillations, the measured sound pressure level is significant across the entire range of lean mean equivalence ratios even if the equivalence ratio oscillations arriving at the flame are out-of-phase with the pressure oscillations. The combustion dynamics are governed primarily by the flame-vortex interactions, while the equivalence ratio oscillations have secondary effects. The equivalence ratio oscillations could generate variations in the combustion dynamics in each cycle under some operating conditions, destabilize the flame at the entire range of the lean equivalence ratios, and increase the value of the mean equivalence ratio at the lean blowout limit. (author)

  20. Single-step fabrication of microfluidic channels filled with nanofibrous membrane using femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Tavangar, Amirhossein; Tan, Bo; Venkatakrishnan, K.

    2010-08-01

    In this paper, we demonstrate a new method of fabricating silicon microfluidic channels filled with a porous nanofibrous structure utilizing a femtosecond laser. The nanofibrous structure can act as a membrane used for microfiltration. This method allows us to generate both the microfluidic channel and the fibrous nanostructure in a single step under ambient conditions. Due to laser irradiation, a large number of nanoparticles ablate from the channel surface, and then aggregate and grow into porous nanofibrous structures and fill the channels. Energy dispersive x-ray spectroscopy (EDS) analysis was conducted to examine the oxygen concentration in the membrane structure. Our results demonstrated that by controlling the laser parameters including pulse repetition, pulse width and scanning speed, different microfluidic channels with a variety of porosity could be obtained.

  1. Active Flow Control on Laminar flow over a Backward facing step

    NASA Astrophysics Data System (ADS)

    Mushyam, Aditya; Bergada, Josep M.

    2015-09-01

    In the present study, two dimensional flow over a backward-facing step in laminar flow regime with application of active flow control (AFC) technique is analysed. The aim of the present work is to gauge the effectiveness of implementing AFC to reduce drag and study its effects on flow characteristics. In order to analyse the influence of AFC on the boundary layer and the downstream vortex shedding, two different kinds of AFC techniques have been used in this study namely zero net mass flow actuators and fluidic actuators. A parametric non dimensional analysis has been carried out by varying the frequency from 0.025 to 0.1 and jet amplitude from 0.05 and 1. Four different positions of the groove were simulated; groove was respectively located at 0.024a, 0.047a, 0.072a and 0.097a, measured upstream from the right side upper edge. Three different non dimensional groove widths 0.023a, 0.048a and 0.073a were also evaluated, where a is the step height. The idea behind this study was to determine an optimal configuration to reduce the drag on the step and to suppress the vortex dissipation in the wake of the step. It was observed that when using an AFC frequency ± 10% of the vortex shedding one, was causing the maximum drag reduction. When comparing the effects of zero net mass flow actuators with the fluidic actuators, it was observed that zero net mass flow actuators were more effective.

  2. Investigation of temperature fields in supersonic flow behind a backward-facing step

    NASA Astrophysics Data System (ADS)

    Bedarev, I. A.; Goldfeld, M. A.; Zakharova, Yu. V.; Fedorova, N. N.

    2009-09-01

    The results of numerical modelling and experimental investigations of high-enthalpy turbulent flows in the neighborhood of 90-degree backward-facing steps at the Mach numbers M∞ = 2-4 are presented. The experiments were conducted in the hot-shot wind tunnel IT-302M of ITAM SB RAS. The computations were carried out on the basis of the full Favres-averaged Navier — Stokes equations augmented by the Wilcox turbulence model. The temperature factor influence on the flow structure in the separated zone and temperature distributions was investigated numerically for different Mach numbers. The wall temperature is shown to affect significantly the quantity and sizes of recirculation vortices as well as the temperature distribution in the zone of flow separation and reattachment. The computational results are compared with experimental data on the pressure distribution on the model surface and the wave structure of the flow.

  3. Investigation of Particle Sampling Bias in the Shear Flow Field Downstream of a Backward Facing Step

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Kjelgaard, Scott O.; Hepner, Timothy E.

    1990-01-01

    The flow field about a backward facing step was investigated to determine the characteristics of particle sampling bias in the various flow phenomena. The investigation used the calculation of the velocity:data rate correlation coefficient as a measure of statistical dependence and thus the degree of velocity bias. While the investigation found negligible dependence within the free stream region, increased dependence was found within the boundary and shear layers. Full classic correction techniques over-compensated the data since the dependence was weak, even in the boundary layer and shear regions. The paper emphasizes the necessity to determine the degree of particle sampling bias for each measurement ensemble and not use generalized assumptions to correct the data. Further, it recommends the calculation of the velocity:data rate correlation coefficient become a standard statistical calculation in the analysis of all laser velocimeter data.

  4. Separated flow behind a backward-facing step under a stationary temperature disturbance

    NASA Astrophysics Data System (ADS)

    Boiko, A. V.; Dovgal, A. V.; Sorokin, A. M.

    2015-11-01

    The flow in the separation region of laminar boundary layer behind a rectangular backward-facing step has been experimentally examined under temperature non-uniformity of the flow. The data were obtained in a subsonic wind tunnel at Reynolds numbers M ≪ 1. The temperature disturbance was generated using a system of Peltier elements provided on the model surface upstream of the separation line. The effect of heating/cooling of the wall on the mean and fluctuating flow components was evaluated using hot-wire measurements. The experimental data were supplemented with calculations of linear-stability characteristics of model velocity profiles in the separated boundary layer. As a result, the response of the separated flow to a stationary thermal perturbation was revealed.

  5. A comparative study of computational solutions to flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Mizukami, M.; Georgiadis, N. J.; Cannon, M. R.

    1993-01-01

    A comparative study was conducted for computational fluid dynamic solutions to flow over a backward-facing step. This flow is a benchmark problem, with a simple geometry, but involves complicated flow physics such as free shear layers, reattaching flow, recirculation, and high turbulence intensities. Three Reynolds-averaged Navier-Stokes flow solvers with k-epsilon turbulence models were used, each using a different solution algorithm: finite difference, finite element, and hybrid finite element - finite difference. Comparisons were made with existing experimental data. Results showed that velocity profiles and reattachment lengths were predicted reasonably well by all three methods, while the skin friction coefficients were more difficult to predict accurately. It was noted that, in general, selecting an appropriate solver for each problem to be considered is important.

  6. Turbulent flow past a backward-facing step - A critical evaluation of two-equation models

    NASA Technical Reports Server (NTRS)

    Thangam, S.; Speziale, C. G.

    1992-01-01

    The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equation models. It is found that the errors in the reported predictions of the k-epsilon model have two major origins: (1) numerical problems arising from inadequate resolution, and (2) inaccurate predictions for normal Reynolds stress differences arising from the use of an isotropic eddy viscosity. Inadequacies in near wall modelling play a substantially smaller role. Detailed calculations are presented which strongly indicate the standard k-epsilon model - when modified with an independently calibrated anisotropic eddy viscosity - can yield surprisingly good predictions for the backstep problem.

  7. Separated and Recovering Turbulent Boundary Layer Flow Behind a Backward Facing Step For Different Reynolds Numbers

    NASA Technical Reports Server (NTRS)

    Jovic, Srba; Kutler, Paul F. (Technical Monitor)

    1994-01-01

    Experimental results for a two-dimensional separated turbulent boundary layer behind a backward facing step for five different Reynolds numbers are reported. Results are presented in the form of tables, graphs and a floppy disk for an easy access of the data. Reynolds number based on the step height was varied by changing the reference velocity upstream of the step, U(sub o), and the step height, h. Hot-wire measurement techniques were used to measure three Reynolds stresses and four triple-velocity correlations. In addition, surface pressure and skin friction coefficients were measured. All hot-wire measurements were acquired in a measuring domain which excluded recirculating flow region due to the directional insensitivity of hot-wires. The downstream extent of the domain from the step was 51 h for the largest and I 14h for the smallest step height. This significant downstream length permitted extensive study of the flow recovery. Prediction of perturbed flows and their recovery is particularly attractive for popular turbulence models since variations of turbulence length and time scales and flow interactions in different regions are generally inadequately predicted. The data indicate that the flow in the free shear layer region behaves like the plane mixing layer up to about 2/3 of the mean reattachment length when the flow interaction with the wall commences the flow recovery to that of an ordinary turbulent boundary layer structure. These changes of the flow do not occur abruptly with the change of boundary conditions. A reattachment region represents a transitional region where the flow undergoes the most dramatic adjustments to the new boundary conditions. Large eddies, created in the upstream free-shear layer region, are being torn, recirculated, reentrained back into the main stream interacting with the incoming flow structure. It is foreseeable that it is quite difficult to describe the physics of this region in a rational and quantitative manner other

  8. Dynamic Behavior of Spiral-Groove and Rayleigh-Step Self-Acting Face Seals

    NASA Technical Reports Server (NTRS)

    Dirusso, Eliseo

    1984-01-01

    Tests were performed to determine the dynamic behavior and establish baseline dynamic data for five self-acting face seals employing Rayleigh-step lift-pads and inward pumping as well as outward-pumping spiral grooves for the lift-generating mechanism. The primary parameters measured in the tests were film thickness, seal seat axial motion, and seal frictional torque. The data show the dynamic response of the film thickness to the motion of the seal seat. The inward-pumping spiral-groove seals exhibited a high-amplitude film thickness vibratory mode with a frequency of four times the shaft speed. This mode was not observed in the other seals tested. The tests also revealed that high film thickness vibration amplitude produces considerably higher average film thickness than do low amplitude film thickness vibrations. The seals were tested at a constant face load of 73 N (16.4 lb) with ambient air at room temperature and atmospheric pressure as the fluid medium. The test speed range was from 7000 to 17000 rpm. Seal tangential speed range was 34.5 to 83.7 m/sec (113 to 274 ft/sec).

  9. KCNE1 divides the voltage sensor movement in KCNQ1/KCNE1 channels into two steps

    NASA Astrophysics Data System (ADS)

    Barro-Soria, Rene; Rebolledo, Santiago; Liin, Sara I.; Perez, Marta E.; Sampson, Kevin J.; Kass, Robert S.; Larsson, H. Peter

    2014-04-01

    The functional properties of KCNQ1 channels are highly dependent on associated KCNE-β subunits. Mutations in KCNQ1 or KCNE subunits can cause congenital channelopathies, such as deafness, cardiac arrhythmias and epilepsy. The mechanism by which KCNE1-β subunits slow the kinetics of KCNQ1 channels is a matter of current controversy. Here we show that KCNQ1/KCNE1 channel activation occurs in two steps: first, mutually independent voltage sensor movements in the four KCNQ1 subunits generate the main gating charge movement and underlie the initial delay in the activation time course of KCNQ1/KCNE1 currents. Second, a slower and concerted conformational change of all four voltage sensors and the gate, which opens the KCNQ1/KCNE1 channel. Our data show that KCNE1 divides the voltage sensor movement into two steps with widely different voltage dependences and kinetics. The two voltage sensor steps in KCNQ1/KCNE1 channels can be pharmacologically isolated and further separated by a disease-causing mutation.

  10. Roughness and Reynolds number effects in turbulent flows over forward facing step

    NASA Astrophysics Data System (ADS)

    Thacher, Eric W.; Essel, Ebenezer E.; Tachie, Mark F.

    2013-11-01

    Experiments were performed to study the effects of Reynolds number and surface roughness on turbulent flows over a forward facing step (FFS). The test conditions include an upstream smooth surface and a smooth FFS (SM-SM), an upstream surface roughened with sand grains and a smooth FFS (SG-SM) and upstream rough surface roughened with sand grains and a FFS roughened with sand grains (SG-SG). In each of the above three test conditions, measurements were made at 9 different Reynolds numbers that varied from 2140 to 9130. The average size of the sand grains was 1.8 mm. A particle image velocimetry technique was used to conduct detailed velocity measurements upstream of the FFS and in the separating and reattachment region over the step. Preliminary results show that the reattachment length increases with Reynolds number but becomes independent of Reynolds number at moderate Reynolds numbers. The reattachment length is independent of upstream roughness at very low Reynolds numbers, however, upstream roughness was observed to decrease the reattachment by 41% at higher Reynolds numbers. The authors acknowledge financial support from NSERC DG.

  11. Combustion in a turbulent mixing layer formed at a rearward-facing step

    NASA Technical Reports Server (NTRS)

    Pitz, R. W.; Daily, J. W.

    1983-01-01

    A premixed propane/air flame was stabilized in a turbulent mixing layer formed at a rearward-facing step. The mean and rms averages of the turbulent velocity flowfield were determined by laser velocimetry for both reacting (phi = 0.57) and nonreacting flows (Re = 15,000-37,000 based on step height). The reacting-flow was visualized by high-speed schlieren photography. Large-scale structures dominate the reacting mixing layer. The growth of the large-scale structures was tied to the propagation of the flame. The linear growth rate of the reacting mixing layer defined by the mean velocity profiles was unchanged by combustion but the virtual origin moves downstream. The reacting mixing layer boundaries based on the mean velocity profiles were shifted toward the recirculation zone and reattachment lengths were shortened by 30 percent. The edge of the flame controlled by the large-scale structure development propagated faster into the incoming reactants than the boundary of the mixing layer given by the mean velocity flowfield. Thus, the region of high velocity gradient did not coincide with the region of high reaction and heat transfer.

  12. Orchestration of step-wise synaptic growth by K+ and Ca2+ channels in Drosophila

    PubMed Central

    Lee, Jihye; Wu, Chun-Fang

    2010-01-01

    Synapse formation is tightly associated with neuronal excitability. We found striking synaptic overgrowth caused by Drosophila K+ channel mutations of the seizure and slowpoke genes, encoding Erg and Ca2+-activated BK channels, respectively. These mutants display two distinct patterns of “satellite” budding from larval motor terminus synaptic boutons. Double-mutant analysis indicates that BK and Erg K+ channels interact with separate sets of synaptic proteins to affect distinct growth steps. Postsynaptic L-type Ca2+ channels, Dmca1D, and PSD-95-like scaffold protein, Discs-Large, are required for satellite budding induced by slowpoke and seizure mutations. Presynaptic cacophony Ca2+ channels and NCAM-like adhesion molecule, FasII, take part in a maturation step that is partially arrested by seizure mutations. Importantly, slowpoke and seizure satellites were both suppressed by rutabaga mutations that disrupt Ca2+/CaM-dependent adenylyl cyclase, demonstrating a convergence of K+ channels of different functional categories in regulation of excitability-dependent Ca2+ influx for triggering cAMP-mediated growth plasticity. PMID:21106821

  13. Starting flow and heat transfer downstream of a backward-facing step

    SciTech Connect

    Tsou, F.K. ); Shihjiun Chen ); Aung, W. )

    1991-08-01

    Experiments are performed to study the starting process of heat transfer downstream of a backward-facing step. A Ludweig tube wind tunnel is employed to produce the incompressible flow, which accelerates from a zero velocity to a steady state value with an accelerating period of 7 ms and a steady-state period of 12 ms. Hot-wire anemometry and heat flux gages are used to measure the flow and heat transfer history, respectively. The onset of transition in the free shear layer shows that the disturbance originates from the top corner of the step, then propagating to the free stream. The velocity and turbulence profiles in the free shear layer reach steady-state values after the leading edge disturbance etraverses to the measurement locations. In regions upstream and far downstream of the step, heat flux history data suggest the transformation of the flow from laminar to transitional and finally to turbulent flow. Hot-wire anemometry measurements indicate high-frequency turbulence with a short characteristic time. In the recirculating region, however, a longer characteristic time is observed because of the existence of large-scale eddies. The dimensionless reattachement length (x{sub r}/H) is shown to increase with time from the bottom corner (x{sub r}/H = 0) in the laminar regime to a maximum value of 13.6 in the transitional regime, and decreases to a constant value of 7.6 in the turbulent regime. The steady-state flow field and heat transfer compare favorably with existing data obtained using steady-state techniques.

  14. Dielectric barrier discharge plasma actuator to control turbulent flow downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Sujar-Garrido, P.; Benard, N.; Moreau, E.; Bonnet, J. P.

    2015-04-01

    The objective of these experiments was to determine the optimal forcing location and unsteady forcing actuation produced by a single dielectric barrier discharge plasma actuator for controlling the flow downstream of a backward-facing step. The investigated configuration is a 30-mm-height step mounted in a closed-loop wind tunnel. The flow velocity is fixed at 15 m/s, corresponding to a Reynolds number based on the step height equal to 3 × 104 ( Re θ = 1400). The control authority of the plasma discharge is highlighted by the time-averaged modification of the reattachment point and by the effects obtained on the turbulent dynamics of the reattached shear layer. Several locations of the device actuator are considered, and a parametric study of the input signal is investigated for each location. This procedure leads to the definition of an optimal control configuration regarding the minimization of the reattachment length. When the actuator—that produces an electrohydrodynamic force resulting in an electric wind jet—is located upstream the separation point, it can manipulate the first stages of the formation of the turbulent free shear layer and consequently to modify the flow dynamics. Maximum effects have been observed when the high voltage is burst modulated at a frequency f BM = 125 Hz with a duty-cycle of 50 %. This forcing corresponds to a Strouhal number based on the momentum thickness equal to 0.011, a value corresponding to the convective instability or Kelvin-Helmholtz instability of the separated shear layer.

  15. The Effect of Backward-Facing Step Height on Instability Growth and Breakdown in Swept Wing Boundary-Layer Transition

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.; Wlezien, Richard W.; King, Rudolph A.; Choudhari, Meelan

    2015-01-01

    A low-speed experiment was performed on a swept at plate model with an imposed pressure gradient to determine the effect of a backward-facing step on transition in a stationary-cross flow dominated flow. Detailed hot-wire boundary-layer measurements were performed for three backward-facing step heights of approximately 36, 45, and 49% of the boundary-layer thickness at the step. These step heights correspond to a subcritical, nearly-critical, and critical case. Three leading-edge roughness configurations were tested to determine the effect of stationary-cross flow amplitude on transition. The step caused a local increase in amplitude of the stationary cross flow for the two larger step height cases, but farther downstream the amplitude decreased and remained below the baseline amplitude. The smallest step caused a slight local decrease in amplitude of the primary stationary cross flow mode, but the amplitude collapsed back to the baseline case far downstream of the step. The effect of the step on the amplitude of the primary cross flow mode increased with step height, however, the stationary cross flow amplitudes remained low and thus, stationary cross flow was not solely responsible for transition. Unsteady disturbances were present downstream of the step for all three step heights, and the amplitudes increased with increasing step height. The only exception is that the lower frequency (traveling crossflow-like) disturbance was not present in the lowest step height case. Positive and negative spikes in instantaneous velocity began to occur for the two larger step height cases and then grew in number and amplitude downstream of reattachment, eventually leading to transition. The number and amplitude of spikes varied depending on the step height and cross flow amplitude. Despite the low amplitude of the disturbances in the intermediate step height case, breakdown began to occur intermittently and the flow underwent a long transition region.

  16. A permeation theory for single-file ion channels: One- and two-step models

    PubMed Central

    Nelson, Peter Hugo

    2011-01-01

    How many steps are required to model permeation through ion channels? This question is investigated by comparing one- and two-step models of permeation with experiment and MD simulation for the first time. In recent MD simulations, the observed permeation mechanism was identified as resembling a Hodgkin and Keynes knock-on mechanism with one voltage-dependent rate-determining step [Jensen , PNAS 107, 5833 (2010)]. These previously published simulation data are fitted to a one-step knock-on model that successfully explains the highly non-Ohmic current–voltage curve observed in the simulation. However, these predictions (and the simulations upon which they are based) are not representative of real channel behavior, which is typically Ohmic at low voltages. A two-step association/dissociation (A/D) model is then compared with experiment for the first time. This two-parameter model is shown to be remarkably consistent with previously published permeation experiments through the MaxiK potassium channel over a wide range of concentrations and positive voltages. The A/D model also provides a first-order explanation of permeation through the Shaker potassium channel, but it does not explain the asymmetry observed experimentally. To address this, a new asymmetric variant of the A/D model is developed using the present theoretical framework. It includes a third parameter that represents the value of the “permeation coordinate” (fractional electric potential energy) corresponding to the triply occupied state n of the channel. This asymmetric A/D model is fitted to published permeation data through the Shaker potassium channel at physiological concentrations, and it successfully predicts qualitative changes in the negative current–voltage data (including a transition to super-Ohmic behavior) based solely on a fit to positive-voltage data (that appear linear). The A/D model appears to be qualitatively consistent with a large group of published MD simulations, but no

  17. A permeation theory for single-file ion channels: one- and two-step models.

    PubMed

    Nelson, Peter Hugo

    2011-04-28

    How many steps are required to model permeation through ion channels? This question is investigated by comparing one- and two-step models of permeation with experiment and MD simulation for the first time. In recent MD simulations, the observed permeation mechanism was identified as resembling a Hodgkin and Keynes knock-on mechanism with one voltage-dependent rate-determining step [Jensen et al., PNAS 107, 5833 (2010)]. These previously published simulation data are fitted to a one-step knock-on model that successfully explains the highly non-Ohmic current-voltage curve observed in the simulation. However, these predictions (and the simulations upon which they are based) are not representative of real channel behavior, which is typically Ohmic at low voltages. A two-step association/dissociation (A/D) model is then compared with experiment for the first time. This two-parameter model is shown to be remarkably consistent with previously published permeation experiments through the MaxiK potassium channel over a wide range of concentrations and positive voltages. The A/D model also provides a first-order explanation of permeation through the Shaker potassium channel, but it does not explain the asymmetry observed experimentally. To address this, a new asymmetric variant of the A/D model is developed using the present theoretical framework. It includes a third parameter that represents the value of the "permeation coordinate" (fractional electric potential energy) corresponding to the triply occupied state n of the channel. This asymmetric A/D model is fitted to published permeation data through the Shaker potassium channel at physiological concentrations, and it successfully predicts qualitative changes in the negative current-voltage data (including a transition to super-Ohmic behavior) based solely on a fit to positive-voltage data (that appear linear). The A/D model appears to be qualitatively consistent with a large group of published MD simulations, but no

  18. Velocity and Temperature Measurements in a Non - Reacting Flow Behind a Backward Facing Step.

    NASA Astrophysics Data System (ADS)

    Wu, Men-Zan Bill

    1992-01-01

    A basic design requirement for aerospace propulsion systems is the inclusion of a flame anchoring region in the combustor. This region must be characterized by highly turbulent flow for enhancing extensive mixing of fuel and air for combustion and by flow velocities lower than the flame propagation speed of the mixture. One such configuration, applicable to ramjet type combustion problems, is that of a backward facing step. The application takes advantage of the flow recirculation region for flameholding, and of the high mixing rates in the free shear layer for enhanced combustion efficiency. The specific effort of this research was to investigate experimentally the temperature and velocity distributions in a flow field, generated by the non-premixed hydrogen combustion behind a backward facing step. The region of interest includes turbulent reacting flow with recirculation. The diagnostics used include laser Doppler velocimetry (LDV), Rayleigh scattering and laser Raman spectroscopy (LRS), which permit in-situ measurements with good spatial and temporal resolution. The velocity measurements were carried out using a two component LDV system. Time averaged measurements were used to acquire mean velocities and turbulence intensities. LRS has been utilized to investigate the temperature or species concentration in high temperature reacting flows. The intensity of the Stokes line of nitrogen was used to infer the temperature of the flow in this study. The temperature distribution obtained using LRS measurement is consistent with those using Rayleigh scattering and thermocouple. The following results were obtained in this study: (1) A comparison of velocity fields for the non-reacting and reacting flows has shown that chemical reaction lengthens the reattachment length of the flowfield. (2) Combustion occurs primarily in the free shear layer with the flame sheet, as indicated by the location of maximum temperature coinciding with the region of maximum turbulence

  19. Electron channeling contrast imaging of atomic steps and threading dislocations in 4H-SiC

    NASA Astrophysics Data System (ADS)

    Picard, Y. N.; Twigg, M. E.; Caldwell, J. D.; Eddy, C. R.; Neudeck, P. G.; Trunek, A. J.; Powell, J. A.

    2007-06-01

    Direct imaging of atomic step morphologies and individual threading dislocations in on-axis epitaxial 4H-SiC surfaces is presented. Topographically sensitive electron images of the crystalline surfaces were obtained through forescattered electron detection inside a conventional scanning electron microscope. This technique, termed electron channeling contrast imaging (ECCI), has been utilized to reveal the configuration of highly stepped, homoepitaxial 4H-SiC films grown on 4H-SiC mesa structures. Individual threading dislocations have been consistently imaged at the core of spiral atomic step morphologies located on the 4H-SiC surfaces. The ability of ECCI to image atomic steps was verified by atomic force microscopy.

  20. Flow control of micro-ramps on supersonic forward-facing step flow

    NASA Astrophysics Data System (ADS)

    Qing-Hu, Zhang; Tao, Zhu; Shihe, Yi; Anping, Wu

    2016-05-01

    The effects of the micro-ramps on supersonic turbulent flow over a forward-facing step (FFS) was experimentally investigated in a supersonic low-noise wind tunnel at Mach number 3 using nano-tracer planar laser scattering (NPLS) and particle image velocimetry (PIV) techniques. High spatiotemporal resolution images and velocity fields of supersonic flow over the testing model were captured. The fine structures and their spatial evolutionary characteristics without and with the micro-ramps were revealed and compared. The large-scale structures generated by the micro-ramps can survive the downstream FFS flowfield. The micro-ramps control on the flow separation and the separation shock unsteadiness was investigated by PIV results. With the micro-ramps, the reduction in the range of the reversal flow zone in streamwise direction is 50% and the turbulence intensity is also reduced. Moreover, the reduction in the average separated region and in separation shock unsteadiness are 47% and 26%, respectively. The results indicate that the micro-ramps are effective in reducing the flow separation and the separation shock unsteadiness. Project supported by the National Natural Science Foundation of China (Grant Nos. 11172326 and 11502280).

  1. The Effect of Micro-ramps on Supersonic Flow over a Forward-Facing Step

    NASA Astrophysics Data System (ADS)

    Zhang, Qing-Hu; Yi, Shi-He; Zhu, Yang-Zhu; Chen, Zhi; Wu, Yu

    2013-04-01

    The effect of micro-ramp control on fully developed turbulent flow over a forward-facing step (FFS) is investigated in a supersonic low-noise wind tunnel at Mach number 3 using nano-tracer planar laser scattering (NPLS) and supersonic particle image velocimetry (PIV) techniques. High spatiotemporal resolution images and the average velocity profiles of supersonic flow over the FFS with and without the control of the micro-ramps are captured. The fine structures of both cases, including the coherent structures of fully developed boundary layer and the large-scale hairpin-like vortices originated from the micro-ramps as well as the interaction of shock waves with the large-scale structures, are revealed and compared. Based on the time-correlation images, the temporal and spatial evolutionary characteristics of the coherent structures are investigated. It is beneficial to understand the dynamic mechanisms of the separated flow and the control mechanisms of the micro-ramps. The size of the separation region is determined by the NPLS and PIV. The results indicate that the control of the micro-ramps is capable of delaying the separation and diminishing the extent of recirculation zone.

  2. Numerical simulation of the turbulent convective buoyant flow of sodium over a backward- facing step

    NASA Astrophysics Data System (ADS)

    Schumm, T.; Frohnapfel, B.; Marocco, L.

    2016-09-01

    A forced convective and a buoyancy-aided turbulent liquid sodium flow over a backward-facing step with a constant heat flux applied on the indented wall is simulated. Linear eddy viscosity models are used for the Reynolds stresses. Turbulent heat fluxes are modelled with a single gradient diffusion hypotheses with two different approaches to evaluate the turbulent Prandtl number. Moreover, the influence of turbulence on heat transfer to sodium is also assessed through simulations with zero turbulent thermal diffusivity. The results are compared with DNS data from literature. The velocity and turbulent kinetic energy profiles predicted by all models are in good agreement with the DNS data. The local Nusselt number trend is qualitatively well captured, however, its magnitude is underestimated by all models for the mixed convection case. For forced convection, the heat transfer is overestimated by all heat flux models. The simulation with neglected turbulent heat transfer shows the best overall agreement for the forced convection case. For the mixed convection best agreement is obtained using a correlation to locally evaluate the turbulent thermal diffusivity.

  3. Flame-vortex interaction driven combustion dynamics in a backward-facing step combustor

    SciTech Connect

    Altay, H. Murat; Speth, Raymond L.; Hudgins, Duane E.; Ghoniem, Ahmed F.

    2009-05-15

    The combustion dynamics of propane-hydrogen mixtures are investigated in an atmospheric pressure, lean, premixed backward-facing step combustor. We systematically vary the equivalence ratio, inlet temperature and fuel composition to determine the stability map of the combustor. Simultaneous pressure, velocity, heat release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When fuel is injected far upstream from the step, the equivalence ratio entering the flame is temporally and spatially uniform, and the combustion dynamics are governed only by flame-vortex interactions. Four distinct dynamic regimes are observed depending on the operating parameters. At high but lean equivalence ratios, the flame is unstable and oscillates strongly as it is wrapped around the large unsteady wake vortex. At intermediate equivalence ratios, weakly oscillating quasi-stable flames are observed. Near the lean blowout limit, long stable flames extending from the corner of the step are formed. At atmospheric inlet temperature, the unstable mode resonates at the 1/4 wavemode of the combustor. As the inlet temperature is increased, the 5/4 wavemode of the combustor is excited at high but lean equivalence ratios, forming the high-frequency unstable flames. Higher hydrogen concentration in the fuel and higher inlet temperatures reduce the equivalence ratios at which the transitions between regimes are observed. We plot combustion dynamics maps or the response curves, that is the overall sound pressure level as a function of the equivalence ratio, for different operating conditions. We demonstrate that numerical results of strained premixed flames can be used to collapse the response curves describing the transitions among the dynamic modes onto a function of the heat release rate parameter alone, rather than a function dependent on the equivalence ratio, inlet temperature and fuel

  4. Variation of nanopore diameter along porous anodic alumina channels by multi-step anodization.

    PubMed

    Lee, Kwang Hong; Lim, Xin Yuan; Wai, Kah Wing; Romanato, Filippo; Wong, Chee Cheong

    2011-02-01

    In order to form tapered nanocapillaries, we investigated a method to vary the nanopore diameter along the porous anodic alumina (PAA) channels using multi-step anodization. By anodizing the aluminum in either single acid (H3PO4) or multi-acid (H2SO4, oxalic acid and H3PO4) with increasing or decreasing voltage, the diameter of the nanopore along the PAA channel can be varied systematically corresponding to the applied voltages. The pore size along the channel can be enlarged or shrunken in the range of 20 nm to 200 nm. Structural engineering of the template along the film growth direction can be achieved by deliberately designing a suitable voltage and electrolyte together with anodization time.

  5. Response of Step-pool Mountain Channels to Wildfire Under Changing Climate-fire Regimes

    NASA Astrophysics Data System (ADS)

    Chin, A.; O'Dowd, A. P.; Storesund, R.; Parker, A.; Roberts-Niemann, C.

    2013-12-01

    The western U.S. is becoming more susceptible to wildfire, even though wildfires have occurred throughout history and pre-history. Warming climates leading to drier conditions have increased the occurrence of wildfires. Fire suppression policies throughout the twentieth century have also allowed fuel loads to build and increased the potential for larger and more frequent fires. These trends have growing impacts on human society, as evidenced in increasing number of structures destroyed and related costs of firefighting and resulting damages. Besides the first-order effects of wildfire, such as burned vegetation and reduced infiltration capacities, changing climate-fire regimes have significant indirect effects on hydrologic and geomorphologic responses. This contribution explores how these changes affect the stability and functioning of step-pool mountain streams in the context of landscape evolution. Step-pool systems are stable features adjusted to the prevailing flow and channel morphology, serving important functions of energy dissipation in high-energy environments. Steps and pools are also important ecologically, as they provide diverse habitats for sensitive organisms. Whereas step-pool channels are typically restructured by flows with recurrence intervals often exceeding 50 years, these flows are reached more frequently under changing climate-fire regimes. Following the Waldo Canyon Fire of June/July 2012, one of several recent wildfires that spread along the Colorado Front Range, we track the stability, destruction, and re-development of step-pool systems in two basins in Pike National Forest using terrestrial LiDAR scanning and surveys of longitudinal profiles and cross sections. We document how the first geomorphologically significant event on 1 July 2013 obliterated the step-pool structure in Williams Canyon, widened river channels and lowered channel beds by as much as one meter. Changes in ecological character accompanied the conversion of channel

  6. A stepped leader model for lightning including charge distribution in branched channels

    SciTech Connect

    Shi, Wei; Zhang, Li; Li, Qingmin

    2014-09-14

    The stepped leader process in negative cloud-to-ground lightning plays a vital role in lightning protection analysis. As lightning discharge usually presents significant branched or tortuous channels, the charge distribution along the branched channels and the stochastic feature of stepped leader propagation were investigated in this paper. The charge density along the leader channel and the charge in the leader tip for each lightning branch were approximated by introducing branch correlation coefficients. In combination with geometric characteristics of natural lightning discharge, a stochastic stepped leader propagation model was presented based on the fractal theory. By comparing simulation results with the statistics of natural lightning discharges, it was found that the fractal dimension of lightning trajectory in simulation was in the range of that observed in nature and the calculation results of electric field at ground level were in good agreement with the measurements of a negative flash, which shows the validity of this proposed model. Furthermore, a new equation to estimate the lightning striking distance to flat ground was suggested based on the present model. The striking distance obtained by this new equation is smaller than the value estimated by previous equations, which indicates that the traditional equations may somewhat overestimate the attractive effect of the ground.

  7. A stepped leader model for lightning including charge distribution in branched channels

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Li, Qingmin; Zhang, Li

    2014-09-01

    The stepped leader process in negative cloud-to-ground lightning plays a vital role in lightning protection analysis. As lightning discharge usually presents significant branched or tortuous channels, the charge distribution along the branched channels and the stochastic feature of stepped leader propagation were investigated in this paper. The charge density along the leader channel and the charge in the leader tip for each lightning branch were approximated by introducing branch correlation coefficients. In combination with geometric characteristics of natural lightning discharge, a stochastic stepped leader propagation model was presented based on the fractal theory. By comparing simulation results with the statistics of natural lightning discharges, it was found that the fractal dimension of lightning trajectory in simulation was in the range of that observed in nature and the calculation results of electric field at ground level were in good agreement with the measurements of a negative flash, which shows the validity of this proposed model. Furthermore, a new equation to estimate the lightning striking distance to flat ground was suggested based on the present model. The striking distance obtained by this new equation is smaller than the value estimated by previous equations, which indicates that the traditional equations may somewhat overestimate the attractive effect of the ground.

  8. Two-Step Inverse Modeling for Estimation of Channel Impurity Pile-up

    NASA Astrophysics Data System (ADS)

    Nagumo, Toshiharu; Takeuchi, Kiyoshi; Akiyama, Yutaka; Hane, Masami

    2008-04-01

    A scheme for estimating the amount of channel impurity pile-up using inverse modeling assuming a simplified effective impurity profile is proposed. Impurity profile is divided into deep and surface regions, and they are evaluated in two steps. In the first step, the impurity profile in the deep region is determined using the shift of threshold voltage, and then in the second step, the impurity profile in the surface region is determined using the threshold voltage. By taking drain-induced barrier lowering (DIBL) into account, this scheme can be used to estimate the effective impurity profile in short-channel devices, and thus, can be used to evaluate the gate length dependence of the channel impurity pile-up. Evaluated results on n-type metal-oxide-semiconductor field-effect transistors (MOSFETs) indicate that the impurity pile-up is strong and gate-length-dependent in spike-annealed MOSFETs, whereas laser-annealed MOSFETs show almost no impurity pile-up. The proposed scheme can be used to clearly detect such process condition dependence, and therefore, is helpful for process optimization.

  9. Entrainment effects in periodic forcing of the flow over a backward-facing step

    NASA Astrophysics Data System (ADS)

    Berk, T.; Medjnoun, T.; Ganapathisubramani, B.

    2017-07-01

    The effect of the Strouhal number on periodic forcing of the flow over a backward-facing step (height, H ) is investigated experimentally. Forcing is applied by a synthetic jet at the edge of the step at Strouhal numbers ranging from 0.21

  10. A knowledge-based, two-step procedure for extracting channel networks from noisy dem data

    NASA Astrophysics Data System (ADS)

    Smith, Terence R.; Zhan, Cixiang; Gao, Peng

    We present a new procedure for extracting channel networks from noisy DEM data. The procedure is a knowledge-based, two-step procedure employing both local and nonlocal information. In particular, we employ a model of an ideal drainage network as a source of constraints that must be satisfied by the output of the procedure. We embed these constraints as part of the network extraction procedure. In a first step, the procedure employs the facet model of Haralick to extract valley information from digital images. The constraints employed at this stage relate to conditions indicating reliable valley pixels. In a second step, the procedure applies knowledge of drainage networks to integrate reliable valley points discovered into a network of single-pixel width lines. This network satisfies the constraints imposed by viewing a drainage network as a binary tree in which the channel segments have a one-pixel width. The procedure performs well on DEM data in the example investigated. The overall worst-case performance of the procedure is O( N) log N), but the most computationally intensive step in the procedure is parallelized easily. Hence the procedure is a good candidate for automation.

  11. Fabrication of parylene channels embedded in silicon using a single parylene deposition step

    NASA Astrophysics Data System (ADS)

    Tolstosheeva, Elena; Pimentel, João. V.; Schander, Andreas; Kempen, Ludger; Vellekoop, Michael; Lang, Walter

    2015-06-01

    In-situ integration of microfluidic channels into the microfabrication process flow of implantable microsystems is desirable, for example to enable efficient drug delivery. We propose a fabrication method for such microfluidic channels using parylene C, a biocompatible material whose inert nature favours water flow. A single deposition of parylene C enabled monolithical integration of fully-sealed micro-channels in a silicon substrate. The channel geometry was predefined by etching 100 μm-deep grooves into a silicon substrate. A PVC foil was fixed manually on the wafer and served as a top-cover for the grooves. The wafers were coated with the adhesion promoter AdPro Poly® and a 15 μm-thick parylene C film was deposited conformally into the grooves-foil enclosed space. The outgasing nature of the PVC foil hindered the adhesion of parylene C, allowing the foil to be peeled off easily from the parylene surface. The functionality of the fully-sealed parylene channels, embedded in the silicon wafer, was verified by injecting DI water with dispersed polystyrene microbeads (diameter 6 μm): the polystyrene beads were successfully transported along the channel. Further, a fully-sealed parylene chamber remained leak-tight throughout a stepwise application of hydrostatic pressures from 0.2 to 3.0 bar (15 s step-interval). In short, our parylene channels are: (1) suitable for microsystem drug-delivery; (2) in-situ enclosed hollow spaces embedded in the silicon substrate, realized with a single parylene deposition; (3) intact at hydrostatic pressures up to 3 bar.

  12. Experimental study on the flow field behind a backward-facing step using a detonation-driven shock tunnel

    NASA Astrophysics Data System (ADS)

    Kim, T.-H.; Yoshikawa, M.; Obara, T.; Ohyagi, S.

    2006-03-01

    The supersonic combustion RAM jet (SCRAM jet) engine is expected to be used in next-generation space planes and hypersonic airliners. To develop the engine, stabilized combustion in a supersonic flow field must be attained even though the residence time of flow is extremely short. A mixing process for breathed air and fuel injected into the supersonic flow field is therefore one of the most important design problems. Because the flow inside the SCRAM jet engine has high enthalpy, an experimental facility is required to produce the high-enthalpy flow field. In this study, a detonation-driven shock tunnel was built to produce a high-enthalpy flow, and a model SCRAM jet engine equipped with a backward-facing step was installed in the test section of the facility to visualize flow fields using a color schlieren technique and high-speed video camera. The fuel was injected perpendicularly to a Mach 3 flow behind the backward-facing step. The height of the step, the injection distance and injection pressure were varied to investigate the effects of the step on air/fuel mixing characteristics. The results show that the recirculation region increases as the fuel injection pressure increases. For injection behind the backward-facing step, mixing efficiency is much higher than with a flat plate. Also, the injection position has a significant influence on the size of the recirculation region generated behind the backward-facing step. The schlieren photograph and pressure histories measured on the bottom wall of the SCRAM jet engine model show that the fuel was ignited behind the step.

  13. Analytical and numerical Riemann solutions of the Saint Venant equations for forward- and backward-facing step flows

    NASA Astrophysics Data System (ADS)

    Bulatov, O. V.

    2014-01-01

    Analytical solutions of the Saint Venant equations for five typical Riemann problems over a forward- or backward-facing step are constructed. These analytical solutions are used as reference ones to estimate the accuracy of simulated discontinuous solutions based on the regularized shallow water equations.

  14. Flow resistance dynamics in step-pool stream channels: 1. Large woody debris and controls on total resistance

    USGS Publications Warehouse

    Wilcox, A.C.; Wohl, E.E.

    2006-01-01

    Flow resistance dynamics in step-pool channels were investigated through physical modeling using a laboratory flume. Variables contributing to flow resistance in step-pool channels were manipulated in order to measure the effects of various large woody debris (LWD) configurations, steps, grains, discharge, and slope on total flow resistance. This entailed nearly 400 flume runs, organized into a series of factorial experiments. Factorial analyses of variance indicated significant two-way and three-way interaction effects between steps, grains, and LWD, illustrating the complexity of flow resistance in these channels. Interactions between steps and LWD resulted in substantially greater flow resistance for steps with LWD than for steps lacking LWD. LWD position contributed to these interactions, whereby LWD pieces located near the lip of steps, analogous to step-forming debris in natural channels, increased the effective height of steps and created substantially higher flow resistance than pieces located farther upstream on step treads. Step geometry and LWD density and orientation also had highly significant effects on flow resistance. Flow resistance dynamics and the resistance effect of bed roughness configurations were strongly discharge-dependent; discharge had both highly significant main effects on resistance and highly significant interactions with all other variables. Copyright 2006 by the American Geophysical Union.

  15. Stepped inlet optical panel

    DOEpatents

    Veligdan, James T.

    2001-01-01

    An optical panel includes stacked optical waveguides having stepped inlet facets collectively defining an inlet face for receiving image light, and having beveled outlet faces collectively defining a display screen for displaying the image light channeled through the waveguides by internal reflection.

  16. Anomalous Increase in Effective Channel Mobility on Gamma-Irradiated p-Channel SiC Metal-Oxide-Semiconductor Field-Effect Transistors Containing Step Bunching

    NASA Astrophysics Data System (ADS)

    Lee, Kin Kiong; Ohshima, Takeshi; Ohi, Akihiko; Itoh, Hisayoshi; Pensl, Gerhard

    2006-09-01

    The influence of gamma-radiation on the electrical characteristics of 6H-SiC p-channel metal-oxide-semiconductor field effect transistors (MOSFETs) containing step bunching is reported. The formation of step bunching perpendicular to the channel inhibited the current flow, whereas such an effect was not seen in devices with step bunching formed parallel to the channel. The effective channel mobility in the latter devices increases with gamma-radiation. This improvement of the hole mobility is attributed partially to the positively trapped charges screened the holes from approaching too close to the surface and partially to the effect of position of these charges, resulting in a reduction of scattering and capture of holes. No enhancement in the effective channel mobility was observed for devices with no step bunching or with root mean square roughness in the channel region less than 4 nm. Further irradiation leads to a decrease in the effective channel mobility due to both the formation of latent interface traps and electrostatics repulsion of holes.

  17. Hot Film Velocity Measurements Downstream of a Swept Backward-Facing Step

    DTIC Science & Technology

    1990-08-01

    CALIBRATION TEMPATURE : S8 deg F PRESSURE: 764.4 mm-hg SAMPLES/READING: SO TEST FREE STREAM VELOCITY: 50 fps CALIBRATION VELOCITY RANGE: 5 TO 70 mphHOTWIRE...PITOT PROBE: 76.75 fps STEP ANGLE: i5 degrees DISTANCE FROM STEP: i inches CALIBRATION TEST AND RUN NO.: CALiZg92 CALIBRATION TEMPATURE : 44 deg F

  18. Phenomenological study of subsonic turbulent flow over a swept rearward-facing step. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Selby, G. V.

    1982-01-01

    The phenomenology of turbulent, subsonic flow over a swept, rearward-facing step was studied. Effects of variations in step height, sweep angle, base geometry, and end conditions on the 3-D separated flow were examined. The separated flow was visualized using smoke wire, oil drop, and surface tuft techniques. Measurements include surface pressure, reattachment distance and swirl angle. Results indicate: (1) model/test section coupling affects the structure of the separated flow, but spanwise end conditions do not; (2) the independence principle is evidently valid for sweep angles up to 38 deg; (3) a sweep angle/swirl angle correlation exists; and (4) base modifications can significantly reduce the reattachment distance.

  19. Comprehensive Approach to Verification and Validation of CFD Simulations Applied to Backward Facing Step-Application of CFD Uncertainty Analysis

    NASA Technical Reports Server (NTRS)

    Groves, Curtis E.; LLie, Marcel; Shallhorn, Paul A.

    2012-01-01

    There are inherent uncertainties and errors associated with using Computational Fluid Dynamics (CFD) to predict the flow field and there is no standard method for evaluating uncertainty in the CFD community. This paper describes an approach to -validate the . uncertainty in using CFD. The method will use the state of the art uncertainty analysis applying different turbulence niodels and draw conclusions on which models provide the least uncertainty and which models most accurately predict the flow of a backward facing step.

  20. Computation of turbulent flows over backward and forward-facing steps using a near-wall Reynolds stress model

    NASA Technical Reports Server (NTRS)

    Ko, Sung HO

    1993-01-01

    Separation and reattachment of turbulent shear layers is observed in many important engineering applications, yet it is poorly understood. This has motivated many studies on understanding and predicting the processes of separation and reattachment of turbulent shear layers. Both of the situations in which separation is induced by adverse pressure gradient, or by discontinuities of geometry, have attracted attention of turbulence model developers. Formulation of turbulence closure models to describe the essential features of separated turbulent flows accurately is still a formidable task. Computations of separated flows associated with sharp-edged bluff bodies are described. For the past two decades, the backward-facing step flow, the simplest separated flow, has been a popular test case for turbulence models. Detailed studies on the performance of many turbulence models, including two equation turbulence models and Reynolds stress models, for flows over steps can be found in the papers by Thangam & Speziale and Lasher & Taulbee). These studies indicate that almost all the existing turbulence models fail to accurately predict many important features of back step flow such as reattachment length, recovery rate of the redeveloping boundary layers downstream of the reattachment point, streamlines near the reattachment point, and the skin friction coefficient. The main objectives are to calculate flows over backward and forward-facing steps using the NRSM and to make use of the newest DNS data for detailed comparison. This will give insights for possible improvements of the turbulence model.

  1. Survivorship in Non-Small Cell Lung Cancer: Challenges Faced and Steps Forward.

    PubMed

    Vijayvergia, Namrata; Shah, Prashant C; Denlinger, Crystal S

    2015-09-01

    Improvements in curative therapies and the advent of screening have led to increased numbers of non-small cell lung cancer (NSCLC) survivors. Most survivors have undergone invasive treatment (surgery, radiation therapy, and/or chemotherapy) and carry a higher comorbidity burden than survivors of other cancers. Overall quality of life (QOL) and health-related quality of life (HRQOL) suffer during the treatment phase, with the potential for long-term decline, and both clinical characteristics and treatment impact these measures. Physical and mental components of HRQOL seem to be most at risk for decline. The issues faced by survivors include physical symptoms such as respiratory issues, fatigue, hearing loss, neuropathy, and postsurgical pain; psychological distress leading to depression, financial issues, and poor compliance with recommended guidelines; and fear or risk of recurrence and secondary malignancies. This article summarizes the major issues faced by NSCLC survivors and suggests appropriate management. Future collaborative efforts are needed to further elucidate the complex issues that affect overall QOL and HRQOL in NSCLC survivors and to develop appropriate interventions in this large and diverse survivor population. Copyright © 2015 by the National Comprehensive Cancer Network.

  2. Survivorship in Non–Small Cell Lung Cancer: Challenges Faced and Steps Forward

    PubMed Central

    Vijayvergia, Namrata; Shah, Prashant C.; Denlinger, Crystal S.

    2016-01-01

    Improvements in curative therapies and the advent of screening have led to increased numbers of non–small cell lung cancer (NSCLC) survivors. Most survivors have undergone invasive treatment (surgery, radiation therapy, and/or chemotherapy) and carry a higher comorbidity burden than survivors of other cancers. Overall quality of life (QOL) and health-related quality of life (HRQOL) suffer during the treatment phase, with the potential for long-term decline, and both clinical characteristics and treatment impact these measures. Physical and mental components of HRQOL seem to be most at risk for decline. The issues faced by survivors include physical symptoms such as respiratory issues, fatigue, hearing loss, neuropathy, and postsurgical pain; psychological distress leading to depression, financial issues, and poor compliance with recommended guidelines; and fear or risk of recurrence and secondary malignancies. This article summarizes the major issues faced by NSCLC survivors and suggests appropriate management. Future collaborative efforts are needed to further elucidate the complex issues that affect overall QOL and HRQOL in NSCLC survivors and to develop appropriate interventions in this large and diverse survivor population. PMID:26358799

  3. Hidden Markov Model Analysis of Intermediate Gating Steps Associated with the Pore Gate of Shaker Potassium Channels

    PubMed Central

    Zheng, Jie; Vankataramanan, Lalitha; Sigworth, Fred J.

    2001-01-01

    Cooperativity among the four subunits helps give rise to the remarkable voltage sensitivity of Shaker potassium channels, whose open probability changes tenfold for a 5-mV change in membrane potential. The cooperativity in these channels is thought to arise from a concerted structural transition as the final step in opening the channel. Recordings of single-channel ionic currents from certain other channel types, as well as our previous recordings from T442S mutant Shaker channels, however, display intermediate conductance levels in addition to the fully open and closed states. These sublevels might represent stepwise, rather than concerted, transitions in the final steps of channel activation. Here, we report a similar fine structure in the closing transitions of Shaker channels lacking the mutation. Describing the deactivation time course with hidden Markov models, we find that two subconductance levels are rapidly traversed during most closing transitions of chimeric, high conductance Shaker channels. The lifetimes of these levels are voltage-dependent, with maximal values of 52 and 22 μs at −100 mV, and the voltage dependences of transitions among these states suggest that they arise from equivalent conformational changes occurring in individual subunits. At least one subconductance level is found to be traversed in normal conductance Shaker channels. We speculate that voltage-dependent conformational changes in the subunits give rise to changes in a “pore gate” associated with the selectivity filter region of the channel, producing the subconductance states. As a control for the hidden Markov analysis, we applied the same procedures to recordings of the recovery from N-type inactivation in Shaker channels. These transitions are found to be instantaneous in comparison. PMID:11696611

  4. Effect of wall suction on the stability of compressible subsonic flows over smooth two-dimensional backward-facing steps

    NASA Technical Reports Server (NTRS)

    Al-Maaitah, Ayman A.; Nayfeh, Ali H.; Ragab, Saad A.

    1989-01-01

    The effect of suction on the stability of compressible flows over backward-facing steps is investigated. Mach numbers up to 0.8 are considered. The results show that continuous suction stabilizes the flow outside the separation bubble, but it destabilizes the flow inside it. Nevertheless, the overall N factor decreases as the suction level increases due to the considerable reduction of the separation bubble. For the same suction flow rate, properly distributed suction strips stabilize the flow more than continuous suction. The size of the separation bubble, and hence its effect on the instability can be considerably reduced by placing strips with high suction velocities in the separation region.

  5. Large-eddy simulation of a backward facing step flow using a least-squares spectral element method

    NASA Technical Reports Server (NTRS)

    Chan, Daniel C.; Mittal, Rajat

    1996-01-01

    We report preliminary results obtained from the large eddy simulation of a backward facing step at a Reynolds number of 5100. The numerical platform is based on a high order Legendre spectral element spatial discretization and a least squares time integration scheme. A non-reflective outflow boundary condition is in place to minimize the effect of downstream influence. Smagorinsky model with Van Driest near wall damping is used for sub-grid scale modeling. Comparisons of mean velocity profiles and wall pressure show good agreement with benchmark data. More studies are needed to evaluate the sensitivity of this method on numerical parameters before it is applied to complex engineering problems.

  6. Investigation of a turbulent convective buoyant flow of sodium over a backward- facing step

    NASA Astrophysics Data System (ADS)

    Schumm, Tobias; Frohnapfel, Bettina; Marocco, Luca

    2017-08-01

    The influence of buoyancy-aided mixed convection on the heat transfer downstream of a sudden expansion of a plane channel is investigated by means of the steady-state Reynolds averaged Navier Stokes (RANS) simulation. A linear eddy viscosity model is used to compute the Reynolds stresses. The turbulent heat fluxes are modelled with a single gradient diffusion hypotheses using a local correlation to evaluate the turbulent Prandtl number. The velocity, turbulent kinetic energy and Reynolds shear stress profiles predicted are in good agreement with available DNS data. The local Stanton number trend is qualitatively well captured, however, its magnitude is underestimated for the mixed convection cases. Compared to the case of forced convection, the flow field and heat transfer change significantly. An influence of buoyancy is reported at very low Richardson numbers (Ri). A steady increase in heat transfer with rising influence of buoyancy is observed.

  7. Numerical simulation of a turbulent flame stabilized behind a rearward-facing step

    NASA Technical Reports Server (NTRS)

    Hsiao, C. C.; Oppenheim, A. K.; Chorin, A. J.; Ghoniem, A. F.

    1985-01-01

    Flow of combustible mixtures in a plane channel past a smooth contraction followed by an abrupt expansion, in a typical dump combustor configuration, is modeled by a two-dimensional numerical technique based on the random vortex method. Both the inert and the reacting case are considered. In the latter, the flame is treated as an interface, self-advancing at a prescribed normal burning speed, while the dynamic effects of expansion due to the exothermicity of combustion are expressed by volumetric source lines delineated by its front. Solutions are shown to be in satisfactory agreement with experimental results, especially with respect to global properties such as the average velocity profiles and the reattachment length. The stochastic turbulent velocity components manifest interesting differences, especially near the walls where three-dimensional effects of turbulence are expected to be of importance.

  8. A critical comparison of several low Reynolds number k-epsilon turbulence models for flow over a backward facing step

    NASA Technical Reports Server (NTRS)

    Steffen, C. J., Jr.

    1993-01-01

    Turbulent backward-facing step flow was examined using four low turbulent Reynolds number k-epsilon models and one standard high Reynolds number technique. A tunnel configuration of 1:9 (step height: exit tunnel height) was used. The models tested include: the original Jones and Launder; Chien; Launder and Sharma; and the recent Shih and Lumley formulation. The experimental reference of Driver and Seegmiller was used to make detailed comparisons between reattachment length, velocity, pressure, turbulent kinetic energy, Reynolds shear stress, and skin friction predictions. The results indicated that the use of a wall function for the standard k-epsilon technique did not reduce the calculation accuracy for this separated flow when compared to the low turbulent Reynolds number techniques.

  9. Numerical simulations of three-dimensional laminar flow over a backward facing step; flow near side walls

    NASA Technical Reports Server (NTRS)

    Steinthorsson, Erlendur; Liou, Meng-Sing; Povinelli, Louis A.; Arnone, Andrea

    1993-01-01

    This paper reports the results of numerical simulations of steady, laminar flow over a backward-facing step. The governing equations used in the simulations are the full 'compressible' Navier-Stokes equations, solutions to which were computed by using a cell-centered, finite volume discretization. The convection terms of the governing equations were discretized by using the Advection Upwind Splitting Method (AUSM), whereas the diffusion terms were discretized using central differencing formulas. The validity and accuracy of the numerical solutions were verified by comparing the results to existing experimental data for flow at identical Reynolds numbers in the same back step geometry. The paper focuses attention on the details of the flow field near the side wall of the geometry.

  10. Shear-Layer Manipulation of Backward-Facing Step Flow with Forcing: A Numerical Study

    DTIC Science & Technology

    2014-09-19

    expansion ratio of 10/9, the flow has a Reynolds number of Re = 30000, based on the bulk velocity, Uc = 15 m/ s , and the step height, h = 30 mm. The DBD ...Garrido et al. (2013) and Benard et al. (2014), the BFS flow was manipulated with Dielectric Bar- rier Discharge ( DBD ) plasma actuators. With an...pro- vided that the DBD actuation is modulated with a frequency, f, corresponding to the frequency of the shear-layer mode, of which the measured

  11. Turbulent boundary-layer separation due to a forward-facing step

    NASA Technical Reports Server (NTRS)

    Czarnecki, K. R.; Jackson, M. W.

    1974-01-01

    Pressure distribution tests were made at Mach numbers of 1.61 and 2.20, over a step-height range from 0 to 2.54 centimeters, and an effective Reynolds number range from about 8 to 150 million. The results were compared with some obtained at higher Mach numbers at approximately comparable boundary-layer conditions. The comparison showed several unexplainable anomalies, and pointed up the lack of boundary-layer information necessary for a proper analysis. An analysis of the data indicates the existence of a transverse vortex in the separated-flow region which weakens with increases in Reynolds and Mach number and significantly affects the pressure distributions.

  12. Fine-grained bed patch response to near-bankfull flows in a step-pool channel

    Treesearch

    Daniel A. Marion; Frank. Weirich

    1999-01-01

    Fine-grained bed patches were monitored in a representative step-pool channel in the Arkansas Ouachita Mountains to assess their response to near-bankfull streamflow events. These patches are small, relatively well-sorted bed areas predominantly composed of gravel-size and smaller grains. They occupy 5.2 and 4.1 percent of the active and bankfull channel areas,...

  13. Heat transfer of laminar flow over a 2-D backward facing step with isotropic porous floor segments

    SciTech Connect

    Abu-Hijleh, B.A.K

    1997-07-01

    Forced convection due to fluid flow over a backward facing step has been studied extensively. Flow through porous media occurs in a wide range of engineering applications such as the flow through insulation material, grain storage, and water movement through a geothermal reservoir. Control of the heat transfer characteristics is desirable, and the control mechanism can be either active or passive. Here, the incompressible laminar (Re{sub H} = 100) reattaching flow over a 2-D backward facing step with different length porous floor segments was solved numerically using the finite element method. The focus of this study is the change in the forced convection heat transfer characteristics of the flow field due to the addition of porous floor segments. Several isotropic porous floor segment configurations with different lengths and depths were studied. The porosity of the segments was varied over a wide range by changing the value of the pressure loss coefficient (KP = 10{sup {minus}2}--10{sup 6}). The changes in the local and overall Nusselt number are reported and discussed. Depending on the configuration, axial variation of the local Nusselt number could be altered. For all configurations, the overall Nusselt number decreased by as much as 16% while the maximum local Nusselt number increased by as much as 170%, both relative to their respective values for the reference case of solid floor.

  14. Flow over a rounded backward-facing step, using a z-coordinate model and a σ-coordinate model

    NASA Astrophysics Data System (ADS)

    Rygg, Kristin; Alendal, Guttorm; Haugan, Peter Mosby

    2011-10-01

    Homogeneous, nonrotating flow over a backward-facing rounded step is simulated using the 2D vertical version of two general circulation models, a z-coordinate model—the Massachusetts Institute of Technology general circulation model (MITgcm)—and a σ-coordinate model—the Bergen Ocean Model (BOM). The backward-facing step is a well-known testcase since it is geometrically simple but still embodies important flow characteristics such as separation point, reattachment length, and recirculation of the flow. The study compares the core of the two models and uses constant eddy viscosities and diffusivities. The Reynolds numbers ranges from 2·102 to 2·106. The results correspond with previously published results having a relatively stationary separation point and a fluctuating reattachment length due to downslope propagating eddies released from the reattachment zone for Reynolds numbers higher than or equal to 2 · 104. For Reynolds number within the laminar regime, the flow is stationary. The discrepancies between the models increase by enhancing Reynolds numbers. The σ-coordinate model experiences a reduction in eddy sizes with increasing resolution and Reynolds numbers in correspondence with published experiments, while the size of the eddies are independent of the Reynolds number using the MITgcm. Due to mixing generated by the staircase topography, the z-coordinate model gives a better convergence of the separation point and reattachment length compared with the BOM; however, this conclusion might change with the inclusion of a relevant turbulence scheme.

  15. Submerged and unsubmerged natural hydraulic jumps in a bedrock step-pool mountain channel

    NASA Astrophysics Data System (ADS)

    Vallé, Brett L.; Pasternack, Gregory B.

    2006-12-01

    High-resolution digital elevation models (DEMs) for natural submerged and unsubmerged jump regions were tested against the classical hydraulic jump (CHJ) and engineering analogues that have dominated previous geomorphic and engineering research. DEMs were compared for two discharge conditions. The data showed bed and water surface features of the natural jump regions differ significantly from CHJ conditions and engineering analogues with respect to boundary conditions. Roughness elements were highly irregular in frequency, spacing, size, and orientation, and were comprised of form obliquity and bed scour in boulder-bed and pure-bedrock conditions. The data also showed bed and water surface features of natural jump regions have similarities and deviations from CHJ conditions and engineering analogues with respect to hydraulic characteristics. Several variations were observed in the hydraulic characteristics between the ballistic and sloping jets. Revised conceptual models based on idealized corollaries were developed for the natural jump regions based on upstream energy head relative to the downstream tailwater depth and step geometry. The DEMs highlight the importance of recognizing the interrelationship between spatial transcritical flow structures and localized topographic heterogeneities in bedrock channels.

  16. Large-eddy simulation of particle-laden flow over a backward-facing step using a spectral multidomain method

    NASA Astrophysics Data System (ADS)

    Sengupta, Kaustav; Jacobs, Gustaaf; Mashayek, Farzad

    2008-11-01

    We present an investigation into the particle-laden flow in a dump-combustor configuration. An accurate prediction of particle dispersion within the combustors is necessary for improved design of spray combustion. The instantaneous local particle concentration and turbulent mixing provide insights into the physio-chemical processes that would be encountered in a reacting scenario. The principal difficulty in prediction of particle transport in the dilute flow regime, lies in the accurate description of the underlying complex, turbulent gas flow field featuring reattaching shear layers. Here, we present large-eddy simulations (LESs) of a particle-laden flow over an unconfined and confined backward-facing step at Reynolds numbers of 5000 and 28,000, respectively, using a spectral multidomain LES methodology. The LES captures the carrier flow accurately, while being computationally affordable. One-way coupled equations are considered and particles with different Stokes numbers are studied. The inlet turbulence is modeled using a novel stochastic model that reproduces the second order moments of the fully developed flow upstream of the step. The effects of the turbulent recirculating flow behind the step on particle dispersion are investigated in detail.

  17. Static Longitudinal Stability of a Rocket Vehicle Having a Rear-Facing Step Ahead of the Stabilizing Fins

    NASA Technical Reports Server (NTRS)

    Keynton, Robert J.

    1961-01-01

    Tests were conducted at Mach numbers of 3.96 and 4.65 in the Langley Unitary Plan wind tunnel to determine the static longitudinal stability characteristics of a fin-stabilized rocket-vehicle configuration which had a rearward facing step located upstream of the fins. Two fin sizes and planforms, a delta and a clipped delta, were tested. The angle of attack was varied from 6 deg to -6 deg and the Reynolds number based on model 6 length was about 10 x 10. The configuration with the larger fins (clipped delta) had a center of pressure slightly rearward of and an initial normal-force-curve slope slightly higher than that of the configuration with the smaller fins (delta) as would be expected. Calculations of the stability parameters gave a slightly lower initial slope of the normal-force curve than measured data, probably because of boundary-layer separation ahead of the step. The calculated center of pressure agreed well with the measured data. Measured and calculated increments in the initial slope of the normal-force curve and in the center of pressure, due to changing fins, were in excellent agreement indicating that separated flow downstream of the step did not influence flow over the fins. This result was consistent with data from schlieren photographs.

  18. Equal-mobility bed load transport in a small, step-pool channel in the Ouachita Mountains

    Treesearch

    Daniel A. Marion; Frank Weirich

    2003-01-01

    Abstract: Equal-mobility transport (EMT) of bed load is more evident than size-selective transport during near-bankfull flow events in a small, step-pool channel in the Ouachita Mountains of central Arkansas. Bed load transport modes were studied by simulating five separate runoff events with peak discharges between 0.25 and 1.34 m3...

  19. Coherent structures in a boundary layer and shear layer of a turbulent backward-facing step flow

    NASA Technical Reports Server (NTRS)

    Jovic, Srba; Browne, L. W. B.

    1989-01-01

    A wind tunnel experiment has been carried out at the NASA Ames Research Center to analyze the evolution of coherent structures from a boundary layer to a shear layer in a turbulent, backward-facing, step flow. A miniature X-wire/cold-wire probe has been used in conjunction with two arrays of cold wires, one aligned in the plane of main shear and the other in the spanwise direction of the flow, to detect and characterize delta-scale organized structures in the outer regions of the flow and to provide detailed information concerning these structures. Kinematic features of the events associated with the large scale structures were analyzed and topological pictures of the evolving flow, as well as the contributions to the Reynolds shear stress components are presented.

  20. Effect of wall cooling on the stability of compressible subsonic flows over smooth humps and backward-facing steps

    NASA Technical Reports Server (NTRS)

    Al-Maaitah, Ayman A.; Nayfeh, Ali, H.; Ragab, Saad A.

    1989-01-01

    The effect of wall cooling on the two-dimensional linear stability of subsonic flows over two-dimensional surface imperfections is investigated. Results are presented for flows over smooth humps and backward-facing steps with Mach numbers up to 0.8. The results show that, whereas cooling decreases the viscous instability, it increases the shear-layer instability and hence it increases the growth rates in the separation region. The coexistence of more than one instability mechanism makes a certain degree of wall cooling most effective. For the Mach numbers 0.5 and 0.8, the optimum wall temperatures are about 80 pct and 60 pct of the adiabatic wall temperature, respectively. Increasing the Mach number decreases the effectiveness of cooling slightly and reduces the optimum wall temperature.

  1. Numerical solution of turbulent flow past a backward facing step using a nonlinear K-epsilon model

    NASA Technical Reports Server (NTRS)

    Speziale, C. G.; Ngo, Tuan

    1988-01-01

    The problem of turbulent flow past a backward facing step is important in many technological applications and has been used as a standard test case to evaluate the performance of turbulence models in the prediction of separated flows. It is well known that the commonly used kappa-epsilon (and K-l) models of turbulence yield inaccurate predictions for the reattachment points in this problem. By an analysis of the mean vorticity transport equation, it will be argued that the intrinsically inaccurate prediction of normal Reynolds stress differences by the kappa-epsilon and K-l models is a major contributor to this problem. Computations using a new nonlinear Kappa-epsilon model (which alleviates this deficiency) are made with the TEACH program. Comparisons are made between the improved results predicted by this nonlinear kappa-epsilon model and those obtained from the linear kappa-epsilon model as well as from second-order closure models.

  2. Effect of wall cooling on the stability of compressible subsonic flows over smooth humps and backward-facing steps

    NASA Technical Reports Server (NTRS)

    Al-Maaitah, Ayman A.; Nayfeh, Ali H.; Ragab, Saad A.

    1990-01-01

    The effect of wall cooling on the two-dimensional linear stability of subsonic flows over two-dimensional surface imperfections is investigated. Results are presented for flows over smooth humps and backward-facing steps with Mach numbers up to 0.8. The results show that, whereas cooling decreases the viscous instability, it increases the shear-layer instability and hence it increases the growth rates in the separation region. The coexistence of more than one instability mechanism makes a certain degree of wall cooling most effective. For the Mach numbers 0.5 and 0.8, the optimum wall temperatures are about 80 pct and 60 pct of the adiabatic wall temperature, respectively. Increasing the Mach number decreases the effectiveness of cooling slightly and reduces the optimum wall temperature.

  3. Turbulent separated flow past a backward-facing step: A critical evaluation of two-equation turbulence models

    NASA Technical Reports Server (NTRS)

    Thangam, S.; Speziale, C. G.

    1991-01-01

    The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equation models. It is found that the errors in the reported predictions of the k-epsilon model have two major origins: (1) numerical problems arising from inadequate resolution, and (2) inaccurate predictions for normal Reynolds stress differences arising from the use of an isotropic eddy viscosity. Inadequacies in near wall modelling play a substantially smaller role. Detailed calculations are presented which strongly indicate the standard k-epsilon model - when modified with an independently calibrated anisotropic eddy viscosity - can yield surprisingly good predictions for the backstep problem.

  4. Numerical solution of turbulent flow past a backward facing step using a nonlinear K-epsilon model

    NASA Technical Reports Server (NTRS)

    Speziale, C. G.; Ngo, Tuan

    1987-01-01

    The problem of turbulent flow past a backward facing step is important in many technological applications and has been used as a standard test case to evaluate the performance of turbulence models in the prediction of separated flows. It is well known that the commonly used kappa-epsilon (and K-l) models of turbulence yield inaccurate predictions for the reattachment points in this problem. By an analysis of the mean vorticity transport equation, it will be argued that the intrinsically inaccurate prediction of normal Reynolds stress differences by the Kappa-epsilon and K-l models is a major contributor to this problem. Computations using a new nonlinear kappa-epsilon model (which alleviates this deficiency) are made with the TEACH program. Comparisons are made between the improved results predicted by this nonlinear kappa-epsilon model and those obtained from the linear kappa-epsilon model as well as from second-order closure models.

  5. Structure of backward facing step flow in low Reynolds number controlled by synthetic jet array with different injection velocities

    NASA Astrophysics Data System (ADS)

    Takano, Saneyuki

    2013-11-01

    This study presents detailed structure of separated flow downstream of a backward facing step affected by a non-uniform periodic disturbance along spanwise direction induced by synthetic jet array. The Reynolds number based on the step height ranged from 300 to 900. The frequency of the synthetic jet actuation was selected within the acceptance frequency range of separating shear layer. The periodic disturbance generates periodic transverse vortices whose size and shape change corresponding to the strength of the disturbance. The effect of different injection velocities in the synthetic jet array from those of adjacent jets on the transverse vortex structure and resulting reattachment process is discussed based on the wall shear stress measured by the Micro Flow Sensor (MFS) and flow visualization. Near wall behavior of the transverse vortex above the MFS was related to the sensor output. The results show that non-uniform injection velocity manipulated in the jet array induces difference in the distorted vortex structure and reattachment process in spanwise direction, which strongly depend on the Reynolds number and injection velocities of the synthetic jets.

  6. Numerical study of active flow control over a hypersonic backward-facing step using supersonic jet in near space

    NASA Astrophysics Data System (ADS)

    Guo, Guang-ming; Liu, Hong; Zhang, Bin

    2017-03-01

    Near space has been paid more and more attentions in recent years due to its militarily application value. Direct simulation Monte Carlo (DSMC) which is one of the most successful particle simulation methods in treating rarefied gas dynamics is employed to investigate the flow characteristics of a hypersonic backward-facing step (BFS) under active flow control using supersonic jet in near space. The numerical tool is validated by an experimental flow of dual cusped-plate model, shock wave structures from the numerical simulation are shown in quite good agreement with the experimental result. The influence of altitude and active flow control on BFS flow are then studied in detail. Three parameters, i.e. boundary layer thickness, recirculation region length, and lean angle of the primary recirculation region that is first defined to describe recirculation region shape, are used to evaluate the flow characteristics of every case computed. The numerical results indicate that the main effect of vertical jet upstream of the step is the enhancement of boundary layer thickness downstream of the jet slot, then, it shows a weak influence on recirculation region length and a negligible effect on lean angle. Conversely, the horizontal jet near the step edge can greatly change the recirculation region length by adjusting jetting angle, but it only has a weak influence both on boundary layer thickness and on lean angle for every jetting angle considered. A significant finding is that the recirculation region length is decreased severely in near space compared with experimental and numerical results presented in the open literature.

  7. Flow resistance dynamics in step-pool channels: 2. Partitioning between grain, spill, and woody debris resistance

    USGS Publications Warehouse

    Wilcox, A.C.; Nelson, J.M.; Wohl, E.E.

    2006-01-01

    In step-pool stream channels, flow resistance is created primarily by bed sediments, spill over step-pool bed forms, and large woody debris (LWD). In order to measure resistance partitioning between grains, steps, and LWD in step-pool channels we completed laboratory flume runs in which total resistance was measured with and without grains and steps, with various LWD configurations, and at multiple slopes and discharges. Tests of additive approaches to resistance partitioning found that partitioning estimates are highly sensitive to the order in which components are calculated and that such approaches inflate the values of difficult-to-measure components that are calculated by subtraction from measured components. This effect is especially significant where interactions between roughness features create synergistic increases in resistance such that total resistance measured for combinations of resistance components greatly exceeds the sum of those components measured separately. LWD contributes large proportions of total resistance by creating form drag on individual pieces and by increasing the spill resistance effect of steps. The combined effect of LWD and spill over steps was found to dominate total resistance, whereas grain roughness on step treads was a small component of total resistance. The relative contributions of grain, spill, and woody debris resistance were strongly influenced by discharge and to a lesser extent by LWD density. Grain resistance values based on published formulas and debris resistance values calculated using a cylinder drag approach typically underestimated analogous flume-derived values, further illustrating sources of error in partitioning methods and the importance of accounting for interaction effects between resistance components. Copyright 2006 by the American Geophysical Union.

  8. Step density model of laser sustained ion channel and Coulomb explosion

    SciTech Connect

    Rajouria, Satish Kumar; Malik, H. K.; Tripathi, V. K.; Kumar, Pawan

    2015-02-15

    An analytical model of laser sustained ion channel in plasma is developed, assuming electron density to be zero in the inner region and constant outside. The radius of the channel is such that the ponderomotive force on electrons at the channel boundary is balanced by the channel space charge force. The laser is TM eigen mode of the system with Bessel function profile in the interior and modified Bessel function outside. The channel radius increases with laser intensity and the ratio of laser frequency to plasma frequency. Ion Coulomb explosion of the channel, on longer time scale, produces ion energy distribution, an increasing function of energy with a sharp cutoff equal to electron ponderomotive energy at the channel boundary. At peak laser intensity ≈2×10{sup 19}W/cm{sup 2} at 1 μm wavelength and spot size of 8 μm, the cutoff ion energy in a plasma of density ∼10{sup 19}cm{sup −3} is ∼0.73 MeV.

  9. The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species

    PubMed Central

    Hoyos, Mauricio; Moore, Lee; Williams, P. Stephen; Zborowski, Maciej

    2011-01-01

    The Quadrupole Magnetic Sorter (QMS), employing an annular flow channel concentric with the aperture of a quadrupole magnet, is well established for cell and particle separations. Here we propose a magnetic particle separator comprising a linear array of cylindrical magnets, analogous to the array proposed by Klaus Halbach, mated to a substantially improved form of parallel-plate SPLITT channel, known as the step-SPLITT channel. While the magnetic force and throughput are generally lower than for the QMS, the new separator has advantages in ease of fabrication and the ability to vary the magnetic force to suit the separands. Preliminary experiments yield results consistent with prediction and show promise regarding future separations of cells of biomedical interest. PMID:21399709

  10. The use of a linear Halbach array combined with a step-SPLITT channel for continuous sorting of magnetic species.

    PubMed

    Hoyos, Mauricio; Moore, Lee; Williams, P Stephen; Zborowski, Maciej

    2011-05-01

    The Quadrupole Magnetic Sorter (QMS), employing an annular flow channel concentric with the aperture of a quadrupole magnet, is well established for cell and particle separations. Here we propose a magnetic particle separator comprising a linear array of cylindrical magnets, analogous to the array proposed by Klaus Halbach, mated to a substantially improved form of parallel-plate SPLITT channel, known as the step-SPLITT channel. While the magnetic force and throughput are generally lower than for the QMS, the new separator has advantages in ease of fabrication and the ability to vary the magnetic force to suit the separands. Preliminary experiments yield results consistent with prediction and show promise regarding future separations of cells of biomedical interest.

  11. Gasotransmitter Regulation of Ion Channels: A Key Step in O2 Sensing By the Carotid Body

    PubMed Central

    Prabhakar, Nanduri R.

    2014-01-01

    Carotid bodies detect hypoxia in arterial blood, translating this stimulus into physiological responses via the CNS. It is long established that ion channels are critical to this process. More recent evidence indicates that gasotransmitters exert powerful influences on O2 sensing by the carotid body. Here, we review current understanding of hypoxia-dependent production of gasotransmitters, how they regulate ion channels in the carotid body, and how this impacts carotid body function. PMID:24382871

  12. Mapping of sites facing aqueous environment of voltage-gated proton channel at resting state: a study with PEGylation protection.

    PubMed

    Kurokawa, Tatsuki; Okamura, Yasushi

    2014-01-01

    Hv1 (also named, voltage-sensor only protein, VSOP) lacks an authentic pore domain, and its voltage sensor domain plays both roles in voltage sensing and proton permeation. The activities of a proton channel are intrinsic to protomers of Hv1, while Hv1 is dimeric in biological membranes; cooperative gating is exerted by interaction between two protomers. As the signature pattern conserved among voltage-gated channels and voltage-sensing phosphatase, Hv1 has multiple arginines intervened by two hydrophobic residues on the fourth transmembrane segment, S4. S4 moves upward relative to other helices upon depolarization, causing conformational change possibly leading to the formation of a proton-selective conduction pathway. However, detailed mechanisms of proton-selectivity and gating of Hv1 are unknown. Here we took an approach of PEGylation protection assay to define residues facing the aqueous environment of mouse Hv1 (mHv1). Accessibilities of two maleimide molecules, N-ethylmaleimide (NEM) and 4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid (AMS), were examined on cysteine introduced into individual sites. Only the first arginine on S4 (R1: R201) was inaccessible by NEM and AMS in mHv1. This is consistent with previous results of electrophysiology on the resting state channel, suggesting that the accessibility profile represents the resting state of mHv1. D108, critical for proton selectivity, was accessible by AMS and NEM, suggesting that D108 faces the vestibule. F146, a site critical for blocking by a guanidinium-reagent, was accessible by NEM, suggesting that F146 also faces the inner vestibule. These findings suggest an inner vestibule lined by several residues on S2 including F146, D108 on S1, and the C-terminal half of S4. © 2013.

  13. The Effect of Acoustic Forcing on Instabilities and Breakdown in Swept-Wing Flow over a Backward-Facing Step

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.; Shishkov, Olga; Wlezien, Richard W.; King, Rudolph A.; Choudhari, Meelan

    2016-01-01

    Instability interaction and breakdown were experimentally investigated in the flow over a swept backward-facing step. Acoustic forcing was used to excite the Tollmien-Schlichting (TS) instability and to acquire phase-locked results. The phase-averaged results illustrate the complex nature of the interaction between the TS and stationary cross flow instabilities. The weak stationary cross flow disturbance causes a distortion of the TS wavefront. The breakdown process is characterized by large positive and negative spikes in velocity. The positive spikes occur near the same time and location as the positive part of the TS wave. Higher-order spectral analysis was used to further investigate the nonlinear interactions between the TS instability and the traveling cross flow disturbances. The results reveal that a likely cause for the generation of the spikes corresponds to nonlinear interactions between the TS, traveling cross flow, and stationary cross flow disturbances. The spikes begin at low amplitudes of the unsteady and steady disturbances (2-4% U (sub e) (i.e. boundary layer edge velocity)) but can achieve very large amplitudes (20-30 percent U (sub e) (i.e. boundary layer edge velocity)) that initiate an early, though highly intermittent, breakdown to turbulence.

  14. Fully implicit solutions of the benchmark backward facing step problem using finite element discretization and inexact Newton's method

    SciTech Connect

    McHugh, P.R.; Knoll, D.A.

    1992-01-01

    A fully implicit solution algorithm based on Newton's method is used to solve the steady, incompressible Navier-Stokes and energy equations. An efficiently evaluated numerical Jacobian is used to simplify implementation, and mesh sequencing is used to increase the radius of convergence of the algorithm. We employ finite volume discretization using the power law scheme of Patankar to solve the benchmark backward facing step problem defined by the ASME K-12 Aerospace Heat Transfer Committee. LINPACK banded Gaussian elimination and the preconditioned transpose-free quasi-minimal residual (TFQMR) algorithm of Freund are studied as possible linear equation solvers. Implementation of the preconditioned TFQMR algorithm requires use of the switched evolution relaxation algorithm of Mulder and Van Leer to ensure convergence. The preconditioned TFQMR algorithm is more memory efficient than the direct solver, but our implementation is not as CPU efficient. Results show that for the level of grid refinement used, power law differencing was not adequate to yield the desired accuracy for this problem.

  15. Numerical exploration of mixing and combustion in a dual-mode combustor with backward-facing steps

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Li, Lang-quan; Yan, Li; Liao, Lei

    2016-10-01

    Dual-mode scramjet combustor is the crucial component for the combined cycle engine of space mission vehicles. The Reynolds Averaged Navier-Stokes (RANS) equations, Spalart-Allmaras turbulence model and the finite-rate reaction model have been utilized to investigate the mixing and combustion in a dual-mode combustor with backward-facing steps, and the species distributions and the Mach number profile of a turbulent diffusion combustion problem have been employed to validate the numerical approach. Moreover, the influences of the injection strategy and the fuel equivalence ratio arrangement on its mixing and combustion flow fields have been explored. The obtained results show that the vertical injection is beneficial for mode transition, and an obvious high pressure region is generated with the vertical injection strategy. Accordingly, its mass-weighted average Mach number drops more sharply. The lower total equivalence ratio is beneficial for the mixing augmentation, as well the smaller fuel equivalence ratio discrepancy. However, the larger total equivalence ratio is beneficial for the mode transition.

  16. Computations of a laminar backward-facing step flow at Re=800 with a spectral domain decomposition method

    NASA Astrophysics Data System (ADS)

    Keskar, Jayant; Lyn, D. A.

    1999-02-01

    The two-dimensional laminar incompressible flow over a backward-facing step is computed using a spectral domain decomposition approach. A minimum number of subdomains (two) is used; high resolution being achieved by increasing the order of the basis Chebyshev polynomial. Results for the case of a Reynolds number of 800 are presented and compared in detail with benchmark computations. Stable accurate steady flow solutions were obtained using substantially fewer nodes than in previously reported simulations. In addition, the problem of outflow boundary conditions was examined on a shortened domain. Because of their more global nature, spectral methods are particularly sensitive to imposed boundary conditions, which may be exploited in examining the effect of artificial (non-physical) outflow boundary conditions. Two widely used set of conditions were tested: pseudo stress-free conditions and zero normal gradient conditions. Contrary to previous results using the finite volume approach, the latter is found to yield a qualitatively erroneous yet stable flow-field. Copyright

  17. Atypical Modulation of Face-Elicited Saccades in Autism Spectrum Disorder in a Double-Step Saccade Paradigm

    ERIC Educational Resources Information Center

    Senju, Atsushi; Kikuchi, Yukiko; Akechi, Hironori; Hasegawa, Toshikazu; Tojo, Yoshikuni; Osanai, Hiroo; Johnson, Mark H.

    2011-01-01

    Atypical development of face processing is a major characteristic in autism spectrum disorder (ASD), which could be due to atypical interactions between subcortical and cortical face processing. The current study investigated the saccade planning towards faces in ASD. Seventeen children with ASD and 17 typically developing (TD) children observed a…

  18. Atypical Modulation of Face-Elicited Saccades in Autism Spectrum Disorder in a Double-Step Saccade Paradigm

    ERIC Educational Resources Information Center

    Senju, Atsushi; Kikuchi, Yukiko; Akechi, Hironori; Hasegawa, Toshikazu; Tojo, Yoshikuni; Osanai, Hiroo; Johnson, Mark H.

    2011-01-01

    Atypical development of face processing is a major characteristic in autism spectrum disorder (ASD), which could be due to atypical interactions between subcortical and cortical face processing. The current study investigated the saccade planning towards faces in ASD. Seventeen children with ASD and 17 typically developing (TD) children observed a…

  19. Dynamics of premixed flames in a narrow channel with a step-wise wall temperature

    SciTech Connect

    Kurdyumov, Vadim N.; Pizza, Gianmarco; Frouzakis, Christos E.; Mantzaras, John

    2009-11-15

    The effect of channel height, inflow velocity and wall temperature on the dynamics and stability of unity Lewis number premixed flames in channels with specified wall temperature is investigated with steady and transient numerical simulations using a two-dimensional thermo-diffusive model. The simplified model is capable of capturing many of the transitions and the combustion modes observed experimentally and in direct numerical simulations in micro- and meso-scale channels, and indicates that the thermal flame/wall interaction is the mechanism leading to the observed flame instabilities. Finally, an ad-hoc one-dimensional model based on the flame-sheet approximation is tested in its capacity to reproduce some of the flame dynamics of the two-dimensional thermo-diffusive model. (author)

  20. A Power-Efficient Clustering Protocol for Coal Mine Face Monitoring with Wireless Sensor Networks Under Channel Fading Conditions.

    PubMed

    Ren, Peng; Qian, Jiansheng

    2016-06-07

    This study proposes a novel power-efficient and anti-fading clustering based on a cross-layer that is specific to the time-varying fading characteristics of channels in the monitoring of coal mine faces with wireless sensor networks. The number of active sensor nodes and a sliding window are set up such that the optimal number of cluster heads (CHs) is selected in each round. Based on a stable expected number of CHs, we explore the channel efficiency between nodes and the base station by using a probe frame and the joint surplus energy in assessing the CH selection. Moreover, the sending power of a node in different periods is regulated by the signal fade margin method. The simulation results demonstrate that compared with several common algorithms, the power-efficient and fading-aware clustering with a cross-layer (PEAFC-CL) protocol features a stable network topology and adaptability under signal time-varying fading, which effectively prolongs the lifetime of the network and reduces network packet loss, thus making it more applicable to the complex and variable environment characteristic of a coal mine face.

  1. A Power-Efficient Clustering Protocol for Coal Mine Face Monitoring with Wireless Sensor Networks Under Channel Fading Conditions

    PubMed Central

    Ren, Peng; Qian, Jiansheng

    2016-01-01

    This study proposes a novel power-efficient and anti-fading clustering based on a cross-layer that is specific to the time-varying fading characteristics of channels in the monitoring of coal mine faces with wireless sensor networks. The number of active sensor nodes and a sliding window are set up such that the optimal number of cluster heads (CHs) is selected in each round. Based on a stable expected number of CHs, we explore the channel efficiency between nodes and the base station by using a probe frame and the joint surplus energy in assessing the CH selection. Moreover, the sending power of a node in different periods is regulated by the signal fade margin method. The simulation results demonstrate that compared with several common algorithms, the power-efficient and fading-aware clustering with a cross-layer (PEAFC-CL) protocol features a stable network topology and adaptability under signal time-varying fading, which effectively prolongs the lifetime of the network and reduces network packet loss, thus making it more applicable to the complex and variable environment characteristic of a coal mine face. PMID:27338380

  2. Stereo Particle Image Velocimetry Measurements of Transition Downstream of a Forward-Facing Step in a Swept-Wing Boundary Layer

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.

    2017-01-01

    Stereo particle image velocimetry measurements were performed downstream of a forward-facing step in a stationary-crossflow dominated flow. Three different step heights were studied with the same leading-edge roughness configuration to determine the effect of the step on the evolution of the stationary-crossflow. Above the critical step height, which is approximately 68% of the boundary-layer thickness at the step, the step caused a significant increase in the growth of the stationary crossflow. For the largest step height studied (68%), premature transition occurred shortly downstream of the step. The stationary crossflow amplitude only reached approximately 7% of U(sub e) in this case, which suggests that transition does not occur via the high-frequency secondary instabilities typically associated with stationary crossflow transition. The next largest step of 60% delta still caused a significant impact on the growth of the stationary crossflow downstream of the step, but the amplitude eventually returned to that of the baseline case, and the transition front remained the same. The smallest step height (56%) only caused a small increase in the stationary crossflow amplitude and no change in the transition front. A final case was studied in which the roughness on the leading edge of the model was enhanced for the lowest step height case to determine the impact of the stationary crossflow amplitude on transition. The stationary crossflow amplitude was increased by approximately four times, which resulted in premature transition for this step height. However, some notable differences were observed in the behavior of the stationary crossflow mode, which indicate that the interaction mechanism which results in the increased growth of the stationary crossflow downstream of the step may be different in this case compared to the larger step heights.

  3. The K+ battery-regulating Arabidopsis K+ channel AKT2 is under the control of multiple post-translational steps

    PubMed Central

    Michard, Erwan; Rocha, Marcio; Gomez-Porras, Judith L; González, Wendy; Corrâa, Luiz Gustavo Guedes; Ramírez-Aguilar, Santiago J; Cuin, Tracey Ann

    2011-01-01

    Potassium (K+) is an important nutrient for plants. It serves as a cofactor of various enzymes and as the major inorganic solute maintaining plant cell turgor. In a recent study, an as yet unknown role of K+ in plant homeostasis was shown. It was demonstrated that K+ gradients in vascular tissues can serve as an energy source for phloem (re)loading processes and that the voltage-gated K+ channels of the AKT2-type play a unique role in this process. The AKT2 channel can be converted by phosphorylation of specific serine residues (S210 and S329) into a non-rectifying channel that allows a rapid efflux of K+ from the sieve element/companion cells (SE/CC) complex. The energy of this flux is used by other transporters for phloem (re)loading processes. Nonetheless, the results do indicate that post-translational modifications at S210 and S329 alone cannot explain AKT2 regulation. Here, we discuss the existence of multiple post-translational modification steps that work in concert to convert AKT2 from an inward-rectifying into a non-rectifying K+ channel. PMID:21445013

  4. On kinematics and flow velocity prediction in step-pool channels

    NASA Astrophysics Data System (ADS)

    D'Agostino, V.; Michelini, T.

    2015-06-01

    This paper verifies methods for the prediction of mean flow velocity at the reach scale in mountain streams, investigating the kinematics of a series of two small-scale artificial step-pool sequences and a transitional reach between plane-bed and step-pool under well-controlled hydraulic conditions, and improving the estimation of the energy expenditure between the step crest and the downstream pool. Experimental data were collected using three fish ladder reaches with slopes between 2.6 and 10%. Four types of field measurements were conducted: topographical surveys to extract the thalweg profiles and cross-sectional geometry of reference cross sections; grain size analyses of the bed surface; steady state runs with a given flow rate (0.005-0.234 m3/s), and surveying of the water profile in the most significant cross sections. The following main conclusions were reached: (i) the dominance of spill resistance at the lowest discharge (pool water depth-step height ratios of 0.4) causes primary dimensionless head losses of up to 80%, and these losses progressively decrease to approximately 40% when the water discharge and related pool water depth submerge the upstream step height. A specific predictive equation for the head loss was calibrated and then verified via data from the Rio Cordon. (ii) The verification of literature-sourced equations to predict the reach-averaged flow velocity provided suitable results for several of these equations indicating that the use of a specific step-pool equation does not appear to be crucial to achieving accurate predictions.

  5. A family of variable step-size affine projection adaptive filter algorithms using statistics of channel impulse response

    NASA Astrophysics Data System (ADS)

    Shams Esfand Abadi, Mohammad; AbbasZadeh Arani, Seyed Ali Asghar

    2011-12-01

    This paper extends the recently introduced variable step-size (VSS) approach to the family of adaptive filter algorithms. This method uses prior knowledge of the channel impulse response statistic. Accordingly, optimal step-size vector is obtained by minimizing the mean-square deviation (MSD). The presented algorithms are the VSS affine projection algorithm (VSS-APA), the VSS selective partial update NLMS (VSS-SPU-NLMS), the VSS-SPU-APA, and the VSS selective regressor APA (VSS-SR-APA). In VSS-SPU adaptive algorithms the filter coefficients are partially updated which reduce the computational complexity. In VSS-SR-APA, the optimal selection of input regressors is performed during the adaptation. The presented algorithms have good convergence speed, low steady state mean square error (MSE), and low computational complexity features. We demonstrate the good performance of the proposed algorithms through several simulations in system identification scenario.

  6. Panoramic diagnostics of shear stresses on the channel wall with a step using the liquid crystals

    NASA Astrophysics Data System (ADS)

    Zharkova, G. M.; Kovrizhina, V. N.; Petrov, A. P.; Pod'yachev, S. P.

    2016-11-01

    Measurements results on the shear stresses of surface friction by means of thin-film coatings based on cholesteric liquid crystals and specialized software for digital processing of experimental video are presented in the paper. The calibration dependencies of shear stress relative to the hue and azimuth angle as well as shear stress spatial distribution at subsonic turbulent flow ( V ∝ = 84 m/s) around a step, trapezoidal in plane (Reynolds number calculated for step height h, Re h = 2.57•104), with a base angle of 46° were derived for two geometries of experiment. The experiments demonstrated high sensitivity of liquid crystals to rearrangement of the near-wall flow structure and possibility to obtain quantitative data about mean shear stress levels.

  7. Three-dimensional closed microfluidic channel fabrication by stepper projection single step lithography: the diabolo effect.

    PubMed

    Larramendy, F; Mazenq, L; Temple-Boyer, P; Nicu, L

    2012-01-21

    Microfluidic devices are currently being used in many types of biochemical microsystems for liquid phase analysis in the frame of medical applications. This paper presents a new technique for the realization of microfluidic channels using SU-8, a commonly used epoxy-based negative photo-resist. These microchannels were fabricated by a single stepper UV-photolithography process. By changing the process parameters, e.g. the optical focus depth and the UV exposure dose, well-defined, covered microchannels with various dimensions and aspect ratios were realized and proven to be effective for the fluid transport by capillarity. This technique can easily be used for the fabrication of microfluidic devices in the microanalysis and lab-on-chip applications realm.

  8. Ultrasonic inspection of rocket fuel model using laminated transducer and multi-channel step pulser

    NASA Astrophysics Data System (ADS)

    Mihara, T.; Hamajima, T.; Tashiro, H.; Sato, A.

    2013-01-01

    For the ultrasonic inspection for the packing of solid fuel in a rocket booster, an industrial inspection is difficult. Because the signal to noise ratio in ultrasonic inspection of rocket fuel become worse due to the large attenuation even using lower frequency ultrasound. For the improvement of this problem, we tried to applied the two techniques in ultrasonic inspection, one was the step function pulser system with the super wideband frequency properties and the other was the laminated element transducer. By combining these two techniques, we developed the new ultrasonic measurement system and demonstrated the advantages in ultrasonic inspection of rocket fuel model specimen.

  9. Transverse injection into Mach 2 flow behind a rearward-facing step - A 3-D, compressible flow test case for hypersonic combustor CFD validation

    NASA Technical Reports Server (NTRS)

    Mcdaniel, James C.; Fletcher, Douglas G.; Hartfield, Roy J.; Hollo, Steven D.

    1991-01-01

    A spatially-complete data set of the important primitive flow variables is presented for the complex, nonreacting, 3D unit combustor flow field employing transverse injection into a Mach 2 flow behind a rearward-facing step. A unique wind tunnel facility providing the capability for iodine seeding was built specifically for these measurements. Two optical techniques based on laser-induced-iodine fluorescence were developed and utilized for nonintrusive, in situ flow field measurements. LDA provided both mean and fluctuating velocity component measurements. A thermographic phosphor wall temperature measurement technique was developed and employed. Data from the 2D flow over a rearward-facing step and the complex 3D mixing flow with injection are reported.

  10. Temporal variability and memory in sediment transport in an experimental step-pool channel

    NASA Astrophysics Data System (ADS)

    Saletti, Matteo; Molnar, Peter; Zimmermann, André; Hassan, Marwan A.; Church, Michael

    2015-11-01

    Temporal dynamics of sediment transport in steep channels using two experiments performed in a steep flume (8%) with natural sediment composed of 12 grain sizes are studied. High-resolution (1 s) time series of sediment transport were measured for individual grain-size classes at the outlet of the flume for different combinations of sediment input rates and flow discharges. Our aim in this paper is to quantify (a) the relation of discharge and sediment transport and (b) the nature and strength of memory in grain-size-dependent transport. None of the simple statistical descriptors of sediment transport (mean, extreme values, and quantiles) display a clear relation with water discharge, in fact a large variability between discharge and sediment transport is observed. Instantaneous transport rates have probability density functions with heavy tails. Bed load bursts have a coarser grain-size distribution than that of the entire experiment. We quantify the strength and nature of memory in sediment transport rates by estimating the Hurst exponent and the autocorrelation coefficient of the time series for different grain sizes. Our results show the presence of the Hurst phenomenon in transport rates, indicating long-term memory which is grain-size dependent. The short-term memory in coarse grain transport increases with temporal aggregation and this reveals the importance of the sampling duration of bed load transport rates in natural streams, especially for large fractions.

  11. Channels

    NASA Image and Video Library

    2014-04-29

    Two channels are visible in this image from NASA 2001 Mars Odyssey spacecraft . The smaller one near the bottom did not carve as deeply as the larger channel at the top. The channel near the top of the image is near the origin of Mamers Valles.

  12. Wall-pressure-array measurements beneath a two/three-dimensional separating/reattaching boundary layer over an axisymmetric backward-facing-step

    NASA Astrophysics Data System (ADS)

    Hudy, Laura; Naguib, Ahmed; Humphreys, J. R.; Bartram, Scott

    2003-11-01

    The surface-pressure signature of the structure within a separated flow region was investigated using a microphone array in the NASA Langley Subsonic Basic Research Tunnel. The experimental set-up consisted of an axisymmetric backward-facing step with a section upstream of the step that could rotate to create a 3D boundary layer at separation. In the flow region, 32 flush-mounted Emkay electret microphones detected the pressure signature and 56 static pressure taps characterized the mean pressure. The taps were also used to align the model in the tunnel. Data were acquired for 2D and 3D flow configurations for Reynolds numbers of 5250 and 10500, based on the step height. A spatio-temporal analysis of the data revealed the dominant flow modes in the separating shear layer and their convective characteristics for both the 2D and 3D cases. Furthermore, similarities and differences between the two situations were investigated.

  13. Beamforming of aeroacoustic sources in the time domain: An investigation of the intermittency of the noise radiated by a forward-facing step

    NASA Astrophysics Data System (ADS)

    Fischer, J.; Valeau, V.; Brizzi, L.-E.

    2016-11-01

    The present study investigates the intermittency of the broadband aeroacoustic noise produced by a forward-facing step in a flow. The noise source is viewed as a random succession of the so-called intermittent events of short duration distributed spatially in a source region in the flow. An array processing method based on time-domain beamforming has been developed in order to track systematically the intermittent events, both in the time and space domains. Based on a simulated model of the far-field pressure field, the method is validated in terms of event detection and of performance for recovering the pressure spectrum. The method is then applied to experimental array data taken in an anechoic wind-tunnel at low Mach numbers (not exceeding 0.15) for a forward-facing step of height 30 mm. The results show that some very short intermittent events (with a mean duration of the order of 0.15 ms) can be identified from the array data. The spatial distribution of the intermittent events is found to be in agreement with the frequency domain beamform maps. The probability density functions of the events, in terms of widths and apparition times, are shown to be governed by Gamma laws and indicate random phenomena; it is observed that the statistical distributions vary with the streamwise position downstream and upstream of the step, the trends being in agreement with the source behavior as evidenced by using the frequency-domain beamforming methods. The proposed method is then shown to identify, in terms of emission time, location and temporal width, a succession of short acoustic events that participate to the broadband aeroacoustic noise produced by the step; those random events are likely to be linked to the dynamics of the flow interacting with the step.

  14. Stereo Particle Image Velocimetry Measurements of Transition Downstream of a Backward-Facing Step in a Swept-Wing Boundary Layer

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.; Yao, Chung-Sheng

    2017-01-01

    Stereo particle image velocimetry measurements were performed downstream of a backward-facing step in a stationary-cross flow dominated flow. The PIV measurements exhibit excellent quantitative and qualitative agreement with the previously acquired hotwire data. Instantaneous PIV snapshots reveal new information about the nature and cause of the \\spikes" that occurred prior to breakdown in both the hotwire and PIV data. The PIV snapshots show that the events occur simultaneously across multiple stationary cross flow wavelengths, indicating that this is not simply a local event, but is likely caused by the 2D Tollmien-Schlichting instability that is introduced by the step. While the TS instability is a 2D instability, it is also modulated in the spanwise direction due to interactions with the stationary cross flow, as are the other unsteady disturbances present. Because of this modulation, the "spike" events cause an instantaneous increase of the spanwise modulation of the streamwise and spanwise velocity initially caused by the stationary cross flow. Breakdown appears to be caused by this instantaneous modulation, possibly due to a high-frequency secondary instability similar to a traveling-cross flow breakdown scenario. These results further illuminate the respective roles of the stationary cross flow and unsteady disturbances in transition downstream of a backward-facing step.

  15. Co-evolving Physical and Biological Organization in Step-pool Channels: Experiments from a Restoration Reach on Wildcat Creek, California

    NASA Astrophysics Data System (ADS)

    Chin, A.; O'Dowd, A. P.; Mendez, P. K.; Velasco, K. Z.; Leventhal, R. D.; Storesund, R.; Laurencio, L. R.

    2014-12-01

    Step-pools are important features in fluvial systems. Through energy dissipation, step-pools provide stability in high-energy environments that otherwise may erode and degrade. Although research has focused on geomorphological aspects of step-pool channels, the ecological significance of step-pool streams is increasingly recognized. Step-pool streams often contain higher density and diversity of benthic macroinvertebrates and are critical habitats for organisms such as salmonids and tailed frogs. Step-pools are therefore increasingly used to restore eroding channels and improve ecological conditions. This paper addresses a restoration reach of Wildcat Creek in Berkeley, California that featured an installation of step-pools in 2012. The design framework recognized step-pool formation as a self-organizing process that produces a rhythmic morphology. After placing step particles at locations where step-pools are expected to form according to hydraulic theory, the self-organizing approach allowed fluvial processes to refine the rocks into adjusted sequences over time. In addition, a 30-meter "experimental" reach was created to explore the co-evolution of geomorphological and ecological characteristics. After constructing a plane bed channel, boulders and cobbles piled at the upstream end allowed natural flows to mobilize and sort them into step-pool sequences. Ground surveys and LiDAR recorded the development of step-pool sequences over several seasons. Concurrent sampling of benthic macroinvertebrates documented the formation of biological communities in conjunction with habitat. Biological sampling in an upstream reference reach provided a comparison with the restored reach over time. Results to date show an emergent step-pool channel with steps that segment the plane bed into initial step and pool habitats. Biological communities are beginning to form, showing more distinction among habitat types during some seasons, although they do not yet approach reference

  16. A critical comparison of several low Reynolds number k-epsilon turbulence models for flow over a backward-facing step

    NASA Technical Reports Server (NTRS)

    Steffen, Christopher J., Jr.

    1993-01-01

    Turbulent backward-facing step flow was examined using four low turbulent Reynolds number k-epsilon models and one standard high Reynolds number technique. A tunnel configuration of 1:9 (step height: exit tunnel height) was used. The models tested include: the original Jones and Launder; Chien; Launder and Sharma; and the recent Shih and Lumley formulation. The experimental reference of Driver and Seegmiller was used to make detailed comparisons between reattachment length, velocity, pressure, turbulent kinetic energy, Reynolds shear stress, and skin friction predictions. The results indicated that the use of a wall function for the standard k-epsilon technique did not reduce the calculation accuracy for this separated flow when compared to the low turbulent Reynolds number techniques.

  17. Self-Assembly of Synthetic Metabolons through Synthetic Protein Scaffolds: One-Step Purification, Co-immobilization, and Substrate Channeling

    SciTech Connect

    You, C; Zhang, YHP

    2013-02-01

    One-step purification of a multi-enzyme complex was developed based on a mixture of cell extracts containing three dockerin-containing enzymes and one family 3 cellulose-binding module (CBM3)-containing scaffoldin through high-affinity adsorption on low-cost solid regenerated amorphous cellulose (RAC). The three-enzyme complex, called synthetic metabolon, was self-assembled through the high-affinity interaction between the dockerin in each enzyme and three cohesins in the synthetic scaffoldin. The metabolons were either immobilized on the external surface of RAC or free when the scaffoldin contained an intein between the CBM3 and three cohesins. The immobilized and free metabolons containing triosephosphate isomerase, aldolase, and fructose 1,6-biphosphatase exhibited initial reaction rates 48 and 38 times, respectively, that of the non-complexed three-enzyme mixture at the same enzyme loading. Such reaction rate enhancements indicated strong substrate channeling among synthetic metabolons due to the close spatial organization among cascade enzymes. These results suggested that the construction of synthetic metabolons by using cohesins, dockerins, and cellulose-binding modules from cellulosomes not only decreased protein purification labor and cost for in vitro synthetic biology projects but also accelerated reaction rates by 1 order of magnitude compared to non-complexed enzymes. Synthetic metabolons would be an important biocatalytic module for in vitro and in vivo synthetic biology projects.

  18. Media Naturalness Reduction and Compensatory Channel Expansion: A Study of Online and Face-to-Face Sections of the Same Course

    ERIC Educational Resources Information Center

    Kock, Ned; Garza, Vanessa

    2011-01-01

    This study provides a combined test of the media naturalness and channel expansion theories with a study of communication media perceptions and use outcomes in the context of a college information systems course delivery. Data was collected from undergraduate students at the middle and end of a long semester. Approximately half of the students…

  19. Heat transfer characteristics of rectangular coolant channels with various aspect ratios in the plasma-facing components under fully developed MHD laminar flow

    SciTech Connect

    Takase, K.; Hasan, M.Z.

    1995-12-31

    Convective heat transfer in MHD laminar flow through rectangular channels in the plasma-facing components of a fusion reactor has been analyzed numerically to investigate the effects of channel aspect ratio, defined as the ratio of the lengths of the plasma-facing side to the other side. The adverse effect of the nonuniformity of surface heat flus on Nusselt number (Nu) at the plasma-facing side can be alleviated by increasing the aspect ratio of a rectangular duct. At the center and corner of the plasma-facing side of a square duct, the Nu of non-MHD flow are 6.8 and 2.2, respectively, for uniform surface heat flux. In the presence of a strong magnetic field, Nu at the center and corner increases to 22 and 3.6, respectively. However, when the heat flux is highly nonuniform, as in the plasma-facing components, Nu decreases from 22 to 3.1 at the center and from 3.6 to 3.1 at the corner. When the aspect ratio is increased to 4, Nu at the center and corner increase to 5 and 4.7. Along the circumference of a rectangular channel, there are locations where the wall temperature is equal to or less than the bulk coolant temperature, thus making the Nu with conventional definition infinity or negative. The ratio between Nu of MHD flow and Nu of non-MHD flow for various aspect ratios is constant in the region of Hartmann number of more than 200 at least. On the other hand, its ratio increases monotonously with increasing the aspect ratio.

  20. Stochastic estimation of a two/three-dimensional separating/reattaching boundary layer flow field downstream of an axisymmetric backward-facing step

    NASA Astrophysics Data System (ADS)

    Hudy, Laura; Naguib, Ahmed; Humphreys, William; Bartram, Scott

    2004-11-01

    The spatio-temporal characteristics of a separating/reattaching flow region were investigated. The experimental set-up consisted of an axisymmetric backward-facing step with a section upstream of the step that could rotate to create a 3D boundary layer at separation. Beneath the flow region, 32 flush-mounted microphones detected the pressure signature that was acquired simultaneously with PIV measurements, which captured the velocity field above the surface. Data were obtained for different Reynolds numbers (Re), based on step height: five Re for the 2D flow case, ranging from 6100 to 33200, and two Re, 6100 and 8300, for the 3D case. Multi-point stochastic estimation was used to estimate the dominant flow structures above the wall from the wall-pressure signature and the results were compared with the instantaneous structures obtained from the PIV measurements. In addition, Re effects were explored in the 2D case. Supported by NSF grant CTS0116907 and partial support from ONR

  1. Channels

    NASA Image and Video Library

    2015-11-20

    Today's VIS image shows a number of unnamed channels located on the northeastern margin of Terra Sabaea. Orbit Number: 61049 Latitude: 33.5036 Longitude: 58.6967 Instrument: VIS Captured: 2015-09-18 12:54 http://photojournal.jpl.nasa.gov/catalog/PIA20097

  2. An Experimental Study of a Separated/Reattached Flow Behind a Backward-Facing Step. Re(sub h) = 37,000

    NASA Technical Reports Server (NTRS)

    Jovic, Srba

    1996-01-01

    An experimental study was carried out to investigate turbulent structure of a two-dimensional incompressible separating/reattaching boundary layer behind a backward-facing step. Hot-wire measurement technique was used to measure three Reynolds stresses and higher-order mean products of velocity fluctuations. The Reynolds number, Re(sub h), based on the step height, h, and the reference velocity, U(sub 0), was 37,000. The upstream oncoming flow was fully developed turbulent boundary layer with the Re(sub theta) = 3600. All turbulent properties, such as Reynolds stresses, increase dramatically downstream of the step within an internally developing mixing layer. Distributions of dimensionless mean velocity, turbulent quantities and antisymmetric distribution of triple velocity products in the separated free shear layer suggest that the shear layer above the recirculating region strongly resembles free-shear mixing layer structure. In the reattachment region close to the wall, turbulent diffusion term balances the rate of dissipation since advection and production terms appear to be negligibly small. Further downstream, production and dissipation begin to dominate other transport processes near the wall indicating the growth of an internal turbulent boundary layer. In the outer region, however, the flow still has a memory of the upstream disturbance even at the last measuring station of 51 step-heights. The data show that the structure of the inner layer recovers at a much faster rate than the outer layer structure. The inner layer structure resembles the near-wall structure of a plane zero pressure-gradient turbulent boundary layer (plane TBL) by 25h to 30h, while the outer layer structure takes presumably over 100h.

  3. An experimental study of combustion: The turbulent structure of a reacting shear layer formed at a rearward-facing step. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Pitz, R. W.

    1981-01-01

    A premixed propane-air flame is stabilized in a turbulent free shear layer formed at a rearward-facing step. The mean and rms averages of the turbulent velocity flow field were determined by LDV for both reacting and non-reacting flows. The reaching flow was visualized by high speed schlieren photography. Large scale structures dominate the reacting shear layer. The growth of the large scale structures is tied to the propagation of the flame. The linear growth rate of the reacting shear layer defined by the mean velocity profiles is unchanged by combustion but the virtual origin is shifted downstream. The reacting shear layer based on the mean velocity profiles is shifted toward the recirculation zone and the reattachments lengths are shortened by 30%.

  4. Effects of expansion ratio on the calculation of parallel-walled backward-facing step flows - Comparison of four models of turbulence

    NASA Technical Reports Server (NTRS)

    Sindir, M. M.

    1983-01-01

    This paper presents a numerical study of the effects of expansion ratio on two-dimensional separating and reattaching flows in plane backward-facing step geometries with parallel walls. Closure of the Reynolds equations was achieved by four different turbulence models: k-epsilon, 'modified' k-epsilon, algebraic stress, and 'modified' algebraic stress models. The k-epsilon model relates the Reynolds stresses to the mean rate of strain through the definition of an isotropic turbulent viscosity. The more advanced algebraic stress model calculates the stresses from implicit algebraic relationships containing the stresses themselves, the mean rate of strain, and the turbulent kinetic energy and its dissipation rate. 'Modified' versions of the models employ a new dissipation rate equation whose production term was made more sensitive to streamwise curvature effects. A new nonequilibrium wall function treatment proposed by Chieng and Launder (1980) was also incorporated into each model.

  5. The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: numerical simulation downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Schmeeckle, M. W.

    2014-07-01

    Bed load transport over ripples and dunes in rivers exhibits strong spatial and temporal variability due to the complex turbulence field caused by flow separation at bedform crests. A turbulence-resolving flow model downstream of a backward-facing step, coupled with a model integrating the equations of motion of individual sand grains, is used to investigate the physical interaction between bed load motion and turbulence downstream of separated flow. Large bed load transport events are found to correspond to low-frequency, positive pressure fluctuations. Episodic penetration of fluid into the bed increases the bed stress and moves grains. Fluid penetration events are larger in magnitude near the point of reattachment than further downstream. Models of bed load transport over ripples and dunes must incorporate the effects of these penetration events of high stress and sediment flux.

  6. The role of velocity, pressure, and bed stress fluctuations in bed load transport over bed forms: numerical simulation downstream of a backward-facing step

    NASA Astrophysics Data System (ADS)

    Schmeeckle, M. W.

    2015-02-01

    Bed load transport over ripples and dunes in rivers exhibits strong spatial and temporal variability due to the complex turbulence field caused by flow separation at bedform crests. A turbulence-resolving flow model downstream of a backward-facing step, coupled with a model integrating the equations of motion of individual sand grains, is used to investigate the physical interaction between bed load motion and turbulence downstream of separated flow. Large bed load transport events are found to correspond to low-frequency positive pressure fluctuations. Episodic penetration of fluid into the bed increases the bed stress and moves grains. Fluid penetration events are larger in magnitude near the point of reattachment than farther downstream. Models of bed load transport over ripples and dunes must incorporate the effects of these penetration events of high stress and sediment flux.

  7. Cavbeta-subunit displacement is a key step to induce the reluctant state of P/Q calcium channels by direct G protein regulation.

    PubMed

    Sandoz, Guillaume; Lopez-Gonzalez, Ignacio; Grunwald, Didier; Bichet, Delphine; Altafaj, Xavier; Weiss, Norbert; Ronjat, Michel; Dupuis, Alain; De Waard, Michel

    2004-04-20

    P/Q Ca(2+) channel activity is inhibited by G protein-coupled receptor activation. Channel inhibition requires a direct Gbetagamma binding onto the pore-forming subunit, Ca(v)2.1. It is characterized by biophysical changes, including current amplitude reduction, activation kinetic slowing, and an I-V curve shift, which leads to a reluctant mode. Here, we have characterized the contribution of the auxiliary beta(3)-subunit to channel regulation by G proteins. The shift in I-V to a P/Q reluctant mode is exclusively observed in the presence of beta(3). Along with the observation that Gbetagamma has no effect on the I-V curve of Ca(v)2.1 alone, we propose that the reluctant mode promoted by Gbetagamma corresponds to a state in which the beta(3)-subunit has been displaced from its channel-binding site. We validate this hypothesis with a beta(3)-I-II(2.1) loop chimera construct. Gbetagamma binding onto the I-II(2.1) loop portion of the chimera releases the beta(3)-binding domain and makes it available for binding onto the I-II loop of Ca(v)1.2, a G protein-insensitive channel. This finding is extended to the full-length Ca(v)2.1 channel by using fluorescence resonance energy transfer. Gbetagamma injection into Xenopus oocytes displaces a Cy3-labeled beta(3)-subunit from a GFP-tagged Ca(v)2.1 channel. We conclude that beta-subunit dissociation from the channel complex constitutes a key step in P/Q calcium channel regulation by G proteins that underlies the reluctant state and is an important process for modulating neurotransmission through G protein-coupled receptors.

  8. Time Resolved Stereo Particle Image Velocimetry Measurements of the Instabilities Downstream of a Backward-Facing Step in a Swept-Wing Boundary Layer

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.; Yao, Chung-Sheng

    2017-01-01

    Time-resolved particle image velocimetry (TRPIV) measurements are performed down-stream of a swept backward-facing step, with a height of 49% of the boundary-layer thickness. The results agree well qualitatively with previously reported hotwire measurements, though the amplitudes of the fluctuating components measured using TRPIV are higher. Nonetheless, the low-amplitude instabilities in the flow are fairly well resolved using TR- PIV. Proper orthogonal decomposition is used to study the development of the traveling cross flow and Tollmien-Schlichting (TS) instabilities downstream of the step and to study how they interact to form the large velocity spikes that ultimately lead to transition. A secondary mode within the traveling cross flow frequency band develops with a wavelength close to that of the stationary cross flow instability, so that at a certain point in the phase, it causes an increase in the spanwise modulation initially caused by the stationary cross flow mode. This increased modulation leads to an increase in the amplitude of the TS mode, which, itself, is highly modulated through interactions with the stationary cross flow. When the traveling cross flow and TS modes align in time and space, the large velocity spikes occur. Thus, these three instabilities, which are individually of low amplitude when the spikes start to occur (U'rms/Ue <0.03), interact and combine to cause a large flow disturbance that eventually leads to transition.

  9. Particle Image Velocimetry Measurements of a Two/Three-dimensional Separating/Reattaching Boundary Layer Downstream of an Axisymmetric Backward-facing Step

    NASA Technical Reports Server (NTRS)

    Hudy, Laura M.; Naguib, Ahmed M.; Humphreys, William M.; Bartram, Scott M.

    2005-01-01

    Planar Particle Image Velocimetry measurements were obtained in the separating/reattaching flow region downstream of an axisymmetric backward-facing step. Data were acquired for a two-dimensional (2D) separating boundary layer at five different Reynolds numbers based on step height (Re(sub h)), spanning 5900-33000, and for a three-dimensional (3D) separating boundary layer at Re(sub h) = 5980 and 8081. Reynolds number effects were investigated in the 2D cases using mean-velocity field, streamwise and wall-normal turbulent velocity, and Reynolds stress statistics. Results show that both the reattachment length (x(sub r)) and the secondary separation point are Reynolds number dependent. The reattachment length increased with rising Re(sub h) while the secondary recirculation region decreased in size. These and other Re(sub h) effects were interpreted in terms of changes in the separating boundary layer thickness and wall-shear stress. On the other hand, in the 3D case, it was found that the imposed cross-flow component was relatively weak in comparison to the streamwise component. As a result, the primary influences of three dimensionality only affected the near-separation region rather than the entire separation bubble.

  10. Numerical study of the impact of non-Newtonian blood behavior on flow over a two-dimensional backward facing step.

    PubMed

    Choi, Hyo Won; Barakat, Abdul I

    2005-01-01

    Endothelial cell (EC) responsiveness to shear stress is essential for vasoregulation and plays a role in atherogenesis. Although blood is a non-Newtonian fluid, EC flow studies in vitro are typically performed using Newtonian fluids. The goal of the present study was to determine the impact of non-Newtonian behavior on the flow field within a model flow chamber capable of producing flow disturbance and whose dimensions permit Reynolds and Womersley numbers comparable to those present in vivo. We performed two-dimensional computational fluid dynamic simulations of steady and pulsatile laminar flow of Newtonian and non-Newtonian fluids over a backward facing step. In the non-Newtonian simulations, the fluid was modeled as a shear-thinning Carreau fluid. Steady flow results demonstrate that for Re in the range 50-400, the flow recirculation zone downstream of the step is 22-63% larger for the Newtonian fluid than for the non-Newtonian fluid, while spatial gradients of shear stress are larger for the non-Newtonian fluid. In pulsatile flow, the temporal gradients of shear stress within the flow recirculation zone are significantly larger for the Newtonian fluid than for the non-Newtonian fluid. These findings raise the possibility that in regions of flow disturbance, EC mechanotransduction pathways stimulated by Newtonian and non-Newtonian fluids may be different.

  11. CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.

    USGS Publications Warehouse

    Simon, Andrew; Hupp, Cliff R.

    1987-01-01

    This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of channel evolution in disturbed channels was developed by quantifying bed level trends and recognizing qualitative stages of bank slope development. Development of the bank profile is defined in terms of three dynamic and observable surfaces: (a) vertical face (70 to 90 degrees), (b) upper bank (25 to 50 degrees), and (c) slough line (20 to 25 degrees).

  12. Saturation of the response to stochastic forcing in two-dimensional backward-facing step flow: A self-consistent approximation

    NASA Astrophysics Data System (ADS)

    Mantič-Lugo, Vladislav; Gallaire, François

    2016-12-01

    Selective noise amplifiers are characterized by large linear amplification to external perturbations in a particular frequency range despite their global linear stability. Applying a stochastic forcing with increasing amplitude, the response undergoes a strong nonlinear saturation when compared to the linear estimation. Building upon our previous work, we introduce a predictive model that describes this nonlinear dynamics, and we apply it to a canonical example of selective noise amplifiers: the backward-facing step flow. Rewriting conveniently the stochastic forcing and response in the frequency domain, the model consists in a mean flow equation coupled to the linear response to forcing at each frequency. This coupling is attained by the Reynolds stress, which is constructed by the integral in frequency of the independent responses. We generalize the model for a response to a white noise forcing δ -correlated in space and time restricting the flow dynamics to its most energetic patterns calculated from the optimal harmonic forcing and response of the flow. The model estimates accurately the response saturation when compared to direct numerical simulations, and it correctly approximates the structure of the response and the mean flow modification. It also shows that the response undergoes a selective process governed by the nonlinear gain, which promotes a response structure with an approximately single frequency and wavelength in the whole domain. These results suggest that the mean flow modification by the Reynolds stress is the key nonlinearity in the saturation process of the response to white noise.

  13. Mutations in the S6 Gate Isolate a Late Step in the Activation Pathway and Reduce 4-AP Sensitivity in Shaker Kv Channel

    PubMed Central

    Martinez-Morales, Evelyn; Snyders, Dirk J.; Labro, Alain J.

    2014-01-01

    Kv channels detect changes in the membrane potential via their voltage-sensing domains (VSDs) that control the status of the S6 bundle crossing (BC) gate. The movement of the VSDs results in a transfer of the S4 gating charges across the cell membrane but only the last 10–20% of the total gating charge movement is associated with BC gate opening, which involves cooperative transition(s) in the subunits. Substituting the proline residue P475 in the S6 of the Shaker channel by a glycine or alanine causes a considerable shift in the voltage-dependence of the cooperative transition(s) of BC gate opening, effectively isolating the late gating charge component from the other gating charge that originates from earlier VSD movements. Interestingly, both mutations also abolished Shaker’s sensitivity to 4-aminopyridine, which is a pharmacological tool to isolate the late gating charge component. The alanine substitution (that would promote a α-helical configuration compared to proline) resulted in the largest separation of both gating charge components; therefore, BC gate flexibility appears to be important for enabling the late cooperative step of channel opening. PMID:24411245

  14. Two open states and rate-limiting gating steps revealed by intracellular Na+ block of human KCNQ1 and KCNQ1/KCNE1 K+ channels

    PubMed Central

    Pusch, Michael; Ferrera, Loretta; Friedrich, Thomas

    2001-01-01

    KCNQ1, the first member of a new K+ channel family, associates with the small KCNE1 subunit to form the slow cardiac delayed rectifier current, IKs. Mutations in both genes encoding these channels lead to cardiac arrhythmia. We studied the block by intracellular Na+ of human homomeric KCNQ1 (homomers) and heteromeric KCNQ1/KCNE1 (heteromers) expressed in CHO cells (Chinese hamster ovary cell line) using whole-cell patch recording. In the nominal absence of extracellular K+ and with 65 mm intracellular K+, the replacement of 65 mm intracellular N-methyl-d-glucamine (NMDG+) by 65 mm Na+ induced a decay of outward (K+) currents through homomers after maximal activation reminiscent of an inactivation process. The decay had a time constant in the hundreds of milliseconds range. The inactivation process of homomers was, however, not directly dependent on [Na+]i, as evidenced by unaltered biphasic deactivation at negative voltages. An instantaneous voltage-dependent Na+ block of homomers was revealed using tail current protocols with activating prepulses that saturated the gating processes of the channel. The instantaneous block was partially relieved at very large positive voltages (≥ 60 mV) and in 20 mm extracellular K+. The instantaneous block of homomers was much less pronounced if the tail currents were measured after short activating prepulses, demonstrating the presence of (at least) two open states: a first, relatively [Na+]i-insensitive and a subsequent [Na+]i-sensitive open state; the current decay reflects the transition between the two open states. Heteromers exhibited a very similar instantaneous block by Nai+ independently of the prepulse duration. Heteromers did not show a Nai+-induced current decay. Our results demonstrate the presence of two open states of KCNQ1 channels with different [Na+]i sensitivities. The rate-limiting step of homomeric KCNQ1 gating at positive voltages is the transition between these two open states. The rate-limiting step of the

  15. Two open states and rate-limiting gating steps revealed by intracellular Na+ block of human KCNQ1 and KCNQ1/KCNE1 K+ channels.

    PubMed

    Pusch, M; Ferrera, L; Friedrich, T

    2001-05-15

    KCNQ1, the first member of a new K+ channel family, associates with the small KCNE1 subunit to form the slow cardiac delayed rectifier current, IKs. Mutations in both genes encoding these channels lead to cardiac arrhythmia. We studied the block by intracellular Na+ of human homomeric KCNQ1 (homomers) and heteromeric KCNQ1/KCNE1 (heteromers) expressed in CHO cells (Chinese hamster ovary cell line) using whole-cell patch recording. In the nominal absence of extracellular K+ and with 65 mM intracellular K+, the replacement of 65 mM intracellular N-methyl-D-glucamine (NMDG+) by 65 mM Na+ induced a decay of outward (K+) currents through homomers after maximal activation reminiscent of an inactivation process. The decay had a time constant in the hundreds of milliseconds range. The inactivation process of homomers was, however, not directly dependent on [Na+]i, as evidenced by unaltered biphasic deactivation at negative voltages. An instantaneous voltage-dependent Na+ block of homomers was revealed using tail current protocols with activating prepulses that saturated the gating processes of the channel. The instantaneous block was partially relieved at very large positive voltages (> or = 60 mV) and in 20 mM extracellular K+. The instantaneous block of homomers was much less pronounced if the tail currents were measured after short activating prepulses, demonstrating the presence of (at least) two open states: a first, relatively [Na+]i-insensitive and a subsequent [Na+]i-sensitive open state; the current decay reflects the transition between the two open states. Heteromers exhibited a very similar instantaneous block by Na+i independently of the prepulse duration. Heteromers did not show a Na+i-induced current decay. Our results demonstrate the presence of two open states of KCNQ1 channels with different [Na+]i sensitivities. The rate-limiting step of homomeric KCNQ1 gating at positive voltages is the transition between these two open states. The rate-limiting step of

  16. Fluorescence changes reveal kinetic steps of muscarinic receptor–mediated modulation of phosphoinositides and Kv7.2/7.3 K+ channels

    PubMed Central

    Jensen, Jill B.; Lyssand, John S.; Hague, Chris

    2009-01-01

    G protein–coupled receptors initiate signaling cascades. M1 muscarinic receptor (M1R) activation couples through Gαq to stimulate phospholipase C (PLC), which cleaves phosphatidylinositol 4,5-bisphosphate (PIP2). Depletion of PIP2 closes PIP2-requiring Kv7.2/7.3 potassium channels (M current), thereby increasing neuronal excitability. This modulation of M current is relatively slow (6.4 s to reach within 1/e of the steady-state value). To identify the rate-limiting steps, we investigated the kinetics of each step using pairwise optical interactions likely to represent fluorescence resonance energy transfer for M1R activation, M1R/Gβ interaction, Gαq/Gβ separation, Gαq/PLC interaction, and PIP2 hydrolysis. Electrophysiology was used to monitor channel closure. Time constants for M1R activation (<100 ms) and M1R/Gβ interaction (200 ms) are both fast, suggesting that neither of them is rate limiting during muscarinic suppression of M current. Gαq/Gβ separation and Gαq/PLC interaction have intermediate 1/e times (2.9 and 1.7 s, respectively), and PIP2 hydrolysis (6.7 s) occurs on the timescale of M current suppression. Overexpression of PLC accelerates the rate of M current suppression threefold (to 2.0 s) to become nearly contemporaneous with Gαq/PLC interaction. Evidently, channel release of PIP2 and closure are rapid, and the availability of active PLC limits the rate of M current suppression. PMID:19332618

  17. The Effects of Anti-Black Attitudes and Fear of Rape on Accuracy for the Recognition of Black and White Faces: Another Step Beyond the Layperson's Knowledge.

    ERIC Educational Resources Information Center

    Mack, David B.; And Others

    It was hypothesized that young white women who held antiblack attitudes and who were most fearful of being raped would be less accurate in recognizing photographs of black faces than of white faces, in comparison with young white women without these attitudes and fears. Subjects completed a racial attitude scale and a question measuring their fear…

  18. A two-step ionospheric modeling algorithm considering the impact of GLONASS pseudo-range inter-channel biases

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Yao, Yi-bin; Hu, Yue-ming; Song, Wei-wei

    2017-05-01

    The Global Navigation Satellite System presents a plausible and cost-effective way of computing the total electron content (TEC). But TEC estimated value could be seriously affected by the differential code biases (DCB) of frequency-dependent satellites and receivers. Unlike GPS and other satellite systems, GLONASS adopts a frequency-division multiplexing access mode to distinguish different satellites. This strategy leads to different wavelengths and inter-frequency biases (IFBs) for both pseudo-range and carrier phase observations, whose impacts are rarely considered in ionospheric modeling. We obtained observations from four groups of co-stations to analyze the characteristics of the GLONASS receiver P1P2 pseudo-range IFB with a double-difference method. The results showed that the GLONASS P1P2 pseudo-range IFB remained stable for a period of time and could catch up to several meters, which cannot be absorbed by the receiver DCB during ionospheric modeling. Given the characteristics of the GLONASS P1P2 pseudo-range IFB, we proposed a two-step ionosphere modeling method with the priori IFB information. The experimental analysis showed that the new algorithm can effectively eliminate the adverse effects on ionospheric model and hardware delay parameters estimation in different space environments. During high solar activity period, compared to the traditional GPS + GLONASS modeling algorithm, the absolute average deviation of TEC decreased from 2.17 to 2.07 TECu (TEC unit); simultaneously, the average RMS of GPS satellite DCB decreased from 0.225 to 0.219 ns, and the average deviation of GLONASS satellite DCB decreased from 0.253 to 0.113 ns with a great improvement in over 55%.

  19. Flight-measured base pressure coefficients for thick boundary-layer flow over an aft-facing step for Mach numbers from 0.4 to 2.5

    NASA Technical Reports Server (NTRS)

    Goecke, S. A.

    1973-01-01

    A 0.56-inch thick aft-facing step was located 52.1 feet from the leading edge of the left wing of an XB-70 airplane. A boundary-layer rake at a mirror location on the right wing was used to obtain local flow properties. Reynolds numbers were near 10 to the 8th power, resulting in a relatively thick boundary-layer. The momentum thickness ranged from slightly thinner to slightly thicker than the step height. Surface static pressures forward of the step were obtained for Mach numbers near 0.9, 1.5, 2.0, and 2.4. The data were compared with thin boundary-layer results from flight and wind-tunnel experiments and semiempirical relationships. Significant differences were found between the thick and the thin boundary-layer data.

  20. Partial steps of charge translocation in the nonpumping N139L mutant of Rhodobacter sphaeroides cytochrome c oxidase with a blocked D-channel.

    PubMed

    Siletsky, Sergey A; Zhu, Jiapeng; Gennis, Robert B; Konstantinov, Alexander A

    2010-04-13

    The N139L substitution in the D-channel of cytochrome oxidase from Rhodobacter sphaeroides results in an approximately 15-fold decrease in the turnover number and a loss of proton pumping. Time-resolved absorption and electrometric assays of the F --> O transition in the N139L mutant oxidase result in three major findings. (1) Oxidation of the reduced enzyme by O(2) shows approximately 200-fold inhibition of the F --> O step (k approximately 2 s(-1) at pH 8) which is not compatible with enzyme turnover ( approximately 30 s(-1)). Presumably, an abnormal intermediate F(deprotonated) is formed under these conditions, one proton-deficient relative to a normal F state. In contrast, the F --> O transition in N139L oxidase induced by single-electron photoreduction of intermediate F, generated by reaction of the oxidized enzyme with H(2)O(2), decelerates to an extent compatible with enzyme turnover. (2) In the N139L mutant, the protonic phase of Deltapsi generation coupled to the flash-induced F --> O transition greatly decreases in rate and magnitude and can be assigned to the movement of a proton from E286 to the binuclear site, required for reduction of heme a(3) from the Fe(4+) horizontal lineO(2-) state to the Fe(3+)-OH(-) state. Electrogenic reprotonation of E286 from the inner aqueous phase is missing from the F --> O step in the mutant. (3) In the N139L mutant, the KCN-insensitive rapid electrogenic phase may be composed of two components with lifetimes of approximately 10 and approximately 40 mus and a magnitude ratio of approximately 3:2. The 10 mus phase matches vectorial electron transfer from Cu(A) to heme a, whereas the 40 mus component is assigned to intraprotein proton displacement across approximately 20% of the membrane dielectric thickness. This proton displacement might be triggered by rotation of the charged K362 side chain coupled to heme a reduction. The two components of the rapid electrogenic phase have been resolved subsequently with other D-channel

  1. Fourier Domain Optical Coherence Tomography With 3D and En Face Imaging of the Punctum and Vertical Canaliculus: A Step Toward Establishing a Normative Database.

    PubMed

    Kamal, Saurabh; Ali, Mohammad Javed; Ali, Mohammad Hasnat; Naik, Milind N

    2016-01-01

    To report the features of Fourier domain optical coherence tomography imaging of the normal punctum and vertical canaliculus. Prospective, interventional series of consecutive healthy and asymptomatic adults, who volunteered for optical coherence tomography imaging, were included in the study. Fourier domain optical coherence tomography images of the punctum and vertical canaliculus along with 3D and En face images were captured using the RTVue scanner with a corneal adaptor module and a wide-angled lens. Maximum punctal diameter, mid-canalicular diameter, and vertical canalicular height were calculated. Statistical analysis was performed using Pearson correlation test, and scatter plot matrices were analyzed. A total of 103 puncta of 52 healthy subjects were studied. Although all the images could depict the punctum and vertical canaliculus and all the desired measurements could be obtained, occasional tear debris within the canaliculus was found to be interfering with the imaging. The mean maximum punctal diameter, mid-canalicular diameter, and vertical canalicular height were recorded as 214.71 ± 73 μm, 125.04 ± 60.69 μm, and 890.41 ± 154.76 μm, respectively, with an insignificant correlation between them. The maximum recorded vertical canalicular height in all the cases was far less than the widely reported depth of 2 mm. High-resolution 3D and En face images provided a detailed topography of punctal surface and overview of vertical canaliculus. Fourier domain optical coherence tomography with 3D and En face imaging is a useful noninvasive modality to image the proximal lacrimal system with consistently reproducible high-resolution images. This is likely to help clinicians in the management of proximal lacrimal disorders.

  2. Effect of surface permeability on the structure of a separated turbulent flow and heat transfer behind a backward-facing step

    NASA Astrophysics Data System (ADS)

    Terekhov, V. V.; Terekhov, V. I.

    2017-03-01

    The structure and heat transfer in a turbulent separated flow in a suddenly expanding channel with injection (suction) through a porous wall are numerically simulated with the use of two-dimensional averaged Navier-Stokes equations, energy equations, and v 2- f turbulence model. It is shown that enhancement of the intensity of the transverse mass flux on the wall reduces the separation region length in the case of suction and increases the separation region length in the case of injection up to complete boundary layer displacement. The maximum heat transfer coefficient as a function of permeability is accurately described by the asymptotic theory of a turbulent boundary layer.

  3. Enhanced real-space transfer in δ-doped GaAs/In0.1Ga0.9As/In0.25Ga0.75As two-step channel heterojunctions

    NASA Astrophysics Data System (ADS)

    Su, Jan-Shing; Hsu, Wei-Chou; Lin, Wei; Lin, Yu-Shyan

    1997-10-01

    A two-step channel In0.1Ga0.9As/In0.25Ga0.75As heterostructure real-space transfer transistor grown by low-pressure metalorgonic chemical vapor deposition is implemented. By virtue of δ doping, shallow ohmic contacts and two-step channel, a high peak-to-valley current ratio up to 260 000 at 300 K can be obtained at low collector voltage (Vc=3 V). Moreover, from Shubnikov-de Haas (SdH) measurements, we observe a positive persistent-photoconductivity effect and variations of quantum lifetime. The SdH result is in good agreement with the critical drained-to-source onset voltage of negative differential resistance.

  4. Face pain

    MedlinePlus

    ... face may be caused by a nerve problem, injury, or infection. Face pain may also begin in other places in ... zoster (shingles) or herpes simplex (cold sores) infection Injury to the face Migraine Myofascial pain syndrome Sinusitis or sinus infection ( ...

  5. Attenuation and bit error rate for four co-propagating spatially multiplexed optical communication channels of exactly same wavelength in step index multimode fibers

    NASA Astrophysics Data System (ADS)

    Murshid, Syed H.; Chakravarty, Abhijit

    2011-06-01

    Spatial domain multiplexing (SDM) utilizes co-propagation of exactly the same wavelength in optical fibers to increase the bandwidth by integer multiples. Input signals from multiple independent single mode pigtail laser sources are launched at different input angles into a single multimode carrier fiber. The SDM channels follow helical paths and traverse through the carrier fiber without interfering with each other. The optical energy from the different sources is spatially distributed and takes the form of concentric circular donut shaped rings, where each ring corresponds to an independent laser source. At the output end of the fiber these donut shaped independent channels can be separated either with the help of bulk optics or integrated concentric optical detectors. This presents the experimental setup and results for a four channel SDM system. The attenuation and bit error rate for individual channels of such a system is also presented.

  6. Security: Step by Step

    ERIC Educational Resources Information Center

    Svetcov, Eric

    2005-01-01

    This article provides a list of the essential steps to keeping a school's or district's network safe and sound. It describes how to establish a security architecture and approach that will continually evolve as the threat environment changes over time. The article discusses the methodology for implementing this approach and then discusses the…

  7. Face Lift.

    PubMed

    Wan, Dinah; Small, Kevin H; Barton, Fritz E

    2015-11-01

    After studying this article, the participant should be able to: 1. Identify the essential anatomy of the aging face and its relationship to face-lift surgery. 2. Understand the common operative approaches to the aging face and a historical perspective. 3. Understand and describe the common complications following face lifting and treatment options. Surgical rejuvenation of the aging face remains one of the most commonly performed plastic surgery procedures. This article reviews the anatomy of the face and its impact on surgical correction. In addition, this review discusses the evolution of various face-lift techniques and the current surgical approach to the aging face. Finally, this article discusses potential postoperative complications after rhytidectomy and management solutions.

  8. Game Face

    ERIC Educational Resources Information Center

    Weiner, Jill

    2005-01-01

    In this article, the author discusses "Game Face: Life Lessons Across the Curriculum", a teaching kit that challenges assumptions and builds confidence. Game Face, which is derived from a book and art exhibition, "Game Face: What Does a Female Athlete Look Like?", uses layered and powerful images of women and girls participating in sports to teach…

  9. Anisotropic Transport of Electrons in a Novel FET Channel with Chains of InGaAs Nano-Islands Embedded along Quasi-Periodic Multi-Atomic Steps on Vicinal (111)B GaAs

    SciTech Connect

    Akiyama, Y.; Kawazu, T.; Noda, T.; Sakaki, H.

    2010-01-04

    We have studied electron transport in n-AlGaAs/GaAs heterojunction FET channels, in which chains of InGaAs nano-islands are embedded along quasi-periodic steps. By using two samples, conductance G{sub para}(V{sub g}) parallel to the steps and G{sub perp}(V{sub g}) perpendicular to them were measured at 80 K as functions of gate voltage V{sub g}. At sufficiently high V{sub g}, G{sub para} at 80 K is several times as high as G{sub perp}, which manifests the anisotropic two-dimensional transport of electrons. When V{sub g} is reduced to -0.7 V, G{sub perp} almost vanishes, while {sub Gpara} stays sizable unless V{sub g} is set below -0.8 V. These results indicate that 'inter-chain' barriers play stronger roles than 'intra-chain' barriers.

  10. Next Step for STEP

    SciTech Connect

    Wood, Claire; Bremner, Brenda

    2013-08-09

    The Siletz Tribal Energy Program (STEP), housed in the Tribe’s Planning Department, will hire a data entry coordinator to collect, enter, analyze and store all the current and future energy efficiency and renewable energy data pertaining to administrative structures the tribe owns and operates and for homes in which tribal members live. The proposed data entry coordinator will conduct an energy options analysis in collaboration with the rest of the Siletz Tribal Energy Program and Planning Department staff. An energy options analysis will result in a thorough understanding of tribal energy resources and consumption, if energy efficiency and conservation measures being implemented are having the desired effect, analysis of tribal energy loads (current and future energy consumption), and evaluation of local and commercial energy supply options. A literature search will also be conducted. In order to educate additional tribal members about renewable energy, we will send four tribal members to be trained to install and maintain solar panels, solar hot water heaters, wind turbines and/or micro-hydro.

  11. The Hydroacoustics of Beveled Steps and Gaps

    DTIC Science & Technology

    2015-11-01

    is determined by the pressure fluctuations on the face of the step. The pressure fluctuations on the top surface of the step were considered to be...cylinder exhibits a separation zone on the leading half of the cylinder, which is similar to the separation zone on a forward facing step. With this...the sound spectra for flow over a forward- facing step, with one modified parameter, gives the spectral shape and scaling of the sound from the

  12. The glutamate transporter EAAT4 in rat cerebellar Purkinje cells: a glutamate-gated chloride channel concentrated near the synapse in parts of the dendritic membrane facing astroglia.

    PubMed

    Dehnes, Y; Chaudhry, F A; Ullensvang, K; Lehre, K P; Storm-Mathisen, J; Danbolt, N C

    1998-05-15

    Antibodies to an excitatory amino acid transporter (EAAT4) label a glycoprotein of approximately 65 kDa strongly in the cerebellum and weakly in the forebrain. Cross-linking of cerebellar proteins with bis(sulfosuccinimidyl) suberate before solubilization causes dimer bands of EAAT4 and both dimer and trimer bands of the other glutamate transporters GLAST (EAAT1) and GLT (EAAT2) to appear on immunoblots. In contrast to GLAST, GLT, and EAAC (EAAT3), EAAT4 is unevenly distributed in the cerebellar molecular layer, being strongly expressed in parasagittal zones. It is located in cerebellar Purkinje cells, and the highest concentrations are seen in ones expressing high levels of zebrin II (aldolase C). The labeling of Purkinje cell spines and thin dendrites is stronger than that of large diameter dendrites and cell bodies. EAAT4 is present at low concentrations in the synaptic membrane, but is highly enriched in the parts of the dendritic and spine membranes facing astrocytes (which express GLAST and GLT) compared with parts facing neuronal membranes, suggesting a functional relationship with glial glutamate transporters. The presence of EAAT4 in intracellular cisterns and multivesicular organelles may reflect turnover of transporter in the plasma membrane. The total Purkinje cell spine surface and the EAAT4 concentration were found to be 1.1 m2/cm3 and 0.2 mg/cm3, respectively, in the molecular layer, corresponding to 1800 molecules/microm2. The juxtasynaptic location of EAAT4 may explain electrophysiological observations predicting the presence of a neuronal glutamate transporter near the release site at a Purkinje cell spine synapse. EAAT4 may function as a combined transporter and inhibitory glutamate receptor.

  13. A Wall of Faces

    ERIC Educational Resources Information Center

    Stevens, Lori

    2008-01-01

    Visitors to the campus of Orland High School (OHS) will never question that they have stepped into a world of the masses: kids, activity, personalities, busyness, and playfulness--a veritable cloud of mild bedlam. The wall of ceramic faces that greets a visitor in the school office is another reminder of the organized chaos that the teachers…

  14. A Wall of Faces

    ERIC Educational Resources Information Center

    Stevens, Lori

    2008-01-01

    Visitors to the campus of Orland High School (OHS) will never question that they have stepped into a world of the masses: kids, activity, personalities, busyness, and playfulness--a veritable cloud of mild bedlam. The wall of ceramic faces that greets a visitor in the school office is another reminder of the organized chaos that the teachers…

  15. Face Painting.

    ERIC Educational Resources Information Center

    Brooks, Diana

    1995-01-01

    Discusses the use of face painting as a technique for making the endangered species issue tangible for children while addressing the complexity of the issue. Children are "given" an animal of their own and are educated about the animal while having their faces painted to resemble the animal. (LZ)

  16. Another record of significant regional variation in toxicity of Tityus serrulatus venom in Brazil: a step towards understanding the possible role of sodium channel modulators.

    PubMed

    Oliveira, Fagner Neves; Mortari, Márcia Renata; Carneiro, Fabiana Pirani; Guerrero-Vargas, Jimmy Alexander; Santos, Daniel M; Pimenta, Adriano M C; Schwartz, Elisabeth F

    2013-10-01

    The scorpion Tityus serrulatus is responsible for the most severe accidents that have been registered in Brazil, mainly in the state of Minas Gerais (MG), being the lung edema (LE), the main cause of death in these accidents. Although an increased in the number of accidents caused to this species in Federal District (Distrito Federal - DF), it seems that this particular species is not responsible for severe scorpionism cases in this region. Given this observation, we tested the toxicity in mice and compared the ability of T. serrulatus venom from DF (Ts-DF) and Minas Gerais State (Ts-MG) to induce LE in rats. The LD50 of Ts-DF venom was 51.6 μg/mouse, almost twice (1.98) higher than that obtained for Ts-MG venom. The ability of venom (0.5 mg/kg) to induce LE in rats was determined by the wet weight differences between treated and untreated lungs, by pulmonary morphological analyses and by pulmonary vascular permeability (PVP) using the Evans blue protocol. Significant differences in the wet weight of lungs and changes in PVP were found in Ts-MG venom treated rats when compared to rats treated with Ts-DF venom or untreated rats (p < 0.001), but no differences occurred when comparing rats treated with Ts-DF venom and untreated rats (p < 0.05). These results were confirmed by evaluation of pulmonary morphology. Comparison of chromatographic profiles obtained from these venoms (Ts-DF and Ts-MG) using the fractal dimension (D) analysis and the molecular mass fingerprint of the chromatographic fractions showed a higher number of components between 35 and 40% acetonitrile in Ts-MG venom than in Ts-DF venom, indicating a higher diversity of sodium channel modulators in that venom.

  17. Face lift.

    PubMed

    Warren, Richard J; Aston, Sherrell J; Mendelson, Bryan C

    2011-12-01

    After reading this article, the participant should be able to: 1. Identify and describe the anatomy of and changes to the aging face, including changes in bone mass and structure and changes to the skin, tissue, and muscles. 2. Assess each individual's unique anatomy before embarking on face-lift surgery and incorporate various surgical techniques, including fat grafting and other corrective procedures in addition to shifting existing fat to a higher position on the face, into discussions with patients. 3. Identify risk factors and potential complications in prospective patients. 4. Describe the benefits and risks of various techniques. The ability to surgically rejuvenate the aging face has progressed in parallel with plastic surgeons' understanding of facial anatomy. In turn, a more clear explanation now exists for the visible changes seen in the aging face. This article and its associated video content review the current understanding of facial anatomy as it relates to facial aging. The standard face-lift techniques are explained and their various features, both good and bad, are reviewed. The objective is for surgeons to make a better aesthetic diagnosis before embarking on face-lift surgery, and to have the ability to use the appropriate technique depending on the clinical situation.

  18. Recognizing Faces

    ERIC Educational Resources Information Center

    Ellis, Hadyn D.

    1975-01-01

    The proposition that the mechanisms underlying facial recognition are different from those involved in recognizing other classes of pictorial material was assessed following a general review of the literature concerned with recognizing faces. (Author/RK)

  19. Cyclic steps on ice

    NASA Astrophysics Data System (ADS)

    Yokokawa, M.; Izumi, N.; Naito, K.; Parker, G.; Yamada, T.; Greve, R.

    2016-05-01

    Boundary waves often form at the interface between ice and fluid flowing adjacent to it, such as ripples under river ice covers, and steps on the bed of supraglacial meltwater channels. They may also be formed by wind, such as the megadunes on the Antarctic ice sheet. Spiral troughs on the polar ice caps of Mars have been interpreted to be cyclic steps formed by katabatic wind blowing over ice. Cyclic steps are relatives of upstream-migrating antidunes. Cyclic step formation on ice is not only a mechanical but also a thermodynamic process. There have been very few studies on the formation of either cyclic steps or upstream-migrating antidunes on ice. In this study, we performed flume experiments to reproduce cyclic steps on ice by flowing water, and found that trains of steps form when the Froude number is larger than unity. The features of those steps allow them to be identified as ice-bed analogs of cyclic steps in alluvial and bedrock rivers. We performed a linear stability analysis and obtained a physical explanation of the formation of upstream-migrating antidunes, i.e., precursors of cyclic steps. We compared the results of experiments with the predictions of the analysis and found the observed steps fall in the range where the analysis predicts interfacial instability. We also found that short antidune-like undulations formed as a precursor to the appearance of well-defined steps. This fact suggests that such antidune-like undulations correspond to the instability predicted by the analysis and are precursors of cyclic steps.

  20. Growth morphology of vicinal hillocks on the [l brace]101[r brace] face of KH[sub 2]PO[sub 4]: From step-flow to layer-by-layer growth

    SciTech Connect

    De Yoreo, J.J.; Land, T.A.; Dair, B. )

    1994-08-08

    The growth morphologies of vicinal hillocks on KH[sub 2]PO[sub 4][l brace]101[r brace] surfaces have been investigated using atomic force microscopy. Growth occurs on monomolecular steps both by step-flow and through layer-by-layer growth on both dislocation induced steps and 2D nuclei. Dislocation induced hillocks exhibit hollow cores. The circular cross sections of these cores are consistent with an isotropic step edge energy and the core radii are in good agreement with theoretical predictions. From the interisland spacing we estimate the surface diffusion length to be 200 to 300 nm at 300 K.

  1. FACE Act

    THOMAS, 111th Congress

    Rep. Watson, Diane E. [D-CA-33

    2009-06-26

    08/19/2009 Referred to the Subcommittee on Immigration, Citizenship, Refugees, Border Security, and International Law. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  2. FACE Act

    THOMAS, 111th Congress

    Rep. Watson, Diane E. [D-CA-33

    2009-06-26

    House - 08/19/2009 Referred to the Subcommittee on Immigration, Citizenship, Refugees, Border Security, and International Law. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  3. FACE Act

    THOMAS, 111th Congress

    Rep. Watson, Diane E. [D-CA-33

    2009-06-26

    08/19/2009 Referred to the Subcommittee on Immigration, Citizenship, Refugees, Border Security, and International Law. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  4. About Face

    MedlinePlus Videos and Cool Tools

    ... PTSD (posttraumatic stress disorder). Watch the intro This is AboutFace In these videos, Veterans, family members, and clinicians share their experiences with PTSD and PTSD treatment. Choose a topic below to hear what they have to say. What is PTSD? → How ...

  5. Face Prints.

    ERIC Educational Resources Information Center

    Hadash, Dre Ann

    1984-01-01

    Eighth graders made prints of their own faces, using photographic papers and chemicals. Describes the supplies needed and the printing process involved. Because junior high school students are so concerned with self, this was a very meaningful activity for them. (CS)

  6. Funny Faces.

    ERIC Educational Resources Information Center

    Greene, Yvonne

    2000-01-01

    Presents a torn-paper and gadget-print activity for younger students, specifically pre-kindergarten to first grade, that can be done any time over the school year or at Halloween. Discusses how the students create their funny faces and lists the materials needed. (CMK)

  7. Funny Faces.

    ERIC Educational Resources Information Center

    Greene, Yvonne

    2000-01-01

    Presents a torn-paper and gadget-print activity for younger students, specifically pre-kindergarten to first grade, that can be done any time over the school year or at Halloween. Discusses how the students create their funny faces and lists the materials needed. (CMK)

  8. Face detection and eyeglasses detection for thermal face recognition

    NASA Astrophysics Data System (ADS)

    Zheng, Yufeng

    2012-01-01

    Thermal face recognition becomes an active research direction in human identification because it does not rely on illumination condition. Face detection and eyeglasses detection are necessary steps prior to face recognition using thermal images. Infrared light cannot go through glasses and thus glasses will appear as dark areas in a thermal image. One possible solution is to detect eyeglasses and to exclude the eyeglasses areas before face matching. In thermal face detection, a projection profile analysis algorithm is proposed, where region growing and morphology operations are used to segment the body of a subject; then the derivatives of two projections (horizontal and vertical) are calculated and analyzed to locate a minimal rectangle of containing the face area. Of course, the searching region of a pair of eyeglasses is within the detected face area. The eyeglasses detection algorithm should produce either a binary mask if eyeglasses present, or an empty set if no eyeglasses at all. In the proposed eyeglasses detection algorithm, block processing, region growing, and priori knowledge (i.e., low mean and variance within glasses areas, the shapes and locations of eyeglasses) are employed. The results of face detection and eyeglasses detection are quantitatively measured and analyzed using the manually defined ground truths (for both face and eyeglasses). Our experimental results shown that the proposed face detection and eyeglasses detection algorithms performed very well in contrast with the predefined ground truths.

  9. PHOEBE - step by step manual

    NASA Astrophysics Data System (ADS)

    Zasche, P.

    2016-03-01

    An easy step-by-step manual of PHOEBE is presented. It should serve as a starting point for the first time users of PHOEBE analyzing the eclipsing binary light curve. It is demonstrated on one particular detached system also with the downloadable data and the whole procedure is described easily till the final trustworthy fit is being reached.

  10. Nano Step

    NASA Image and Video Library

    2012-09-25

    ISS033-E-007358 (25 Sept. 2012) --- Japan Aerospace Exploration Agency astronaut Aki Hoshide, Expedition 33 flight engineer, services the Nano Step payload in the Kibo laboratory of the International Space Station.

  11. Stepping Forward

    ERIC Educational Resources Information Center

    Jackson, Nancy Mann

    2013-01-01

    Boards of trustees are enduring rough waters, churned by scandals at prominent public universities. In the wake of cases of institutional turmoil, board members at U.S. public universities are navigating myriad challenges facing higher education, including funding shortages, technological changes that are reshaping the way teaching and learning…

  12. Stepping Forward

    ERIC Educational Resources Information Center

    Jackson, Nancy Mann

    2013-01-01

    Boards of trustees are enduring rough waters, churned by scandals at prominent public universities. In the wake of cases of institutional turmoil, board members at U.S. public universities are navigating myriad challenges facing higher education, including funding shortages, technological changes that are reshaping the way teaching and learning…

  13. Effect of N-bromoacetamide on single sodium channel currents in excised membrane patches

    PubMed Central

    1982-01-01

    We have studied the effect of N-bromoacetamide (NBA) on the behavior of single sodium channel currents in excised patches of rat myotube membrane at 10 degree C. Inward sodium currents were activated by voltage steps from holding potentials of about -100 mV to test potentials of -40 mV. The cytoplasmic-face solution was isotonic CsF. Application of NBA or pronase to the cytoplasmic face of the membrane irreversibly removed sodium channel inactivation, as determined by averaged single-channel records. Teh lifetime of the open channel at - 40 mV was increased about 10-fold by NBA treatment without affecting the amplitude of single-channel currents. A binomial analysis was used both before and after treatment to determine the number of channels within the excised patch. NBA was shown to have little effect on activation kinetics, as determined by an examination of both the rising phase of averaged currents and measurements f the delay between the start of the pulse and the first channel opening. Our data support a kinetic model of sodium channel activation in which the rate constant leading back from the open state to the last closed state is slower than expected from a strict Hodgkin-Huxley model. The data also suggest that the normal open-channel lifetime is primarily determined by the inactivation process in the voltage range we have examined. PMID:6281357

  14. Effect of N-bromoacetamide on single sodium channel currents in excised membrane patches.

    PubMed

    Patlak, J; Horn, R

    1982-03-01

    We have studied the effect of N-bromoacetamide (NBA) on the behavior of single sodium channel currents in excised patches of rat myotube membrane at 10 degree C. Inward sodium currents were activated by voltage steps from holding potentials of about -100 mV to test potentials of -40 mV. The cytoplasmic-face solution was isotonic CsF. Application of NBA or pronase to the cytoplasmic face of the membrane irreversibly removed sodium channel inactivation, as determined by averaged single-channel records. Teh lifetime of the open channel at -40 mV was increased about 10-fold by NBA treatment without affecting the amplitude of single-channel currents. A binomial analysis was used both before and after treatment to determine the number of channels within the excised patch. NBA was shown to have little effect on activation kinetics, as determined by an examination of both the rising phase of averaged currents and measurements f the delay between the start of the pulse and the first channel opening. Our data support a kinetic model of sodium channel activation in which the rate constant leading back from the open state to the last closed state is slower than expected from a strict Hodgkin-Huxley model. The data also suggest that the normal open-channel lifetime is primarily determined by the inactivation process in the voltage range we have examined.

  15. Aptamer entrapment in microfluidic channel using one-step sol-gel process, in view of the integration of a new selective extraction phase for lab-on-a-chip.

    PubMed

    Perréard, Camille; d'Orlyé, Fanny; Griveau, Sophie; Liu, Baohong; Bedioui, Fethi; Varenne, Anne

    2017-10-01

    There is a great demand for integrating sample treatment into μTASs. In this context, we developed a new sol-gel phase for extraction of trace compounds in complex matrices. For this purpose, the incorporation of aptamers in silica-based gel within PDMS/glass microfluidic channels was performed for the first time by a one-step sol-gel process. The effective gel attachment onto microchannel walls and aptamer incorporation in the polymerized gel were evaluated using fluorescence microscopy. A good gel stability and aptamer incorporation inside the microchannel was demonstrated upon rinsing and over storage time. The ability of gel-encapsulated aptamers to interact with its specific target (either sulforhodamine B as model fluorescent target, or diclofenac, a pain killer drug) was assessed too. The binding capacity of entrapped aptamers was quantified (in the micromolar range) and the selectivity of the interaction was evidenced. Preservation of aptamers binding affinity to target molecules was therefore demonstrated. Dissociation constant of the aptamer-target complex and interaction selectivity were evaluated similar to those in bulk solution. This opens the way to new selective on-chip SPE techniques for sample pretreatment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Face recognition using 4-PSK joint transform correlation

    NASA Astrophysics Data System (ADS)

    Moniruzzaman, Md.; Alam, Mohammad S.

    2016-04-01

    This paper presents an efficient phase-encoded and 4-phase shift keying (PSK)-based fringe-adjusted joint transform correlation (FJTC) technique for face recognition applications. The proposed technique uses phase encoding and a 4- channel phase shifting method on the reference image which can be pre-calculated without affecting the system processing speed. The 4-channel PSK step eliminates the unwanted zero-order term, autocorrelation among multiple similar input scene objects while yield enhanced cross-correlation output. For each channel, discrete wavelet decomposition preprocessing has been used to accommodate the impact of various 3D facial expressions, effects of noise, and illumination variations. The performance of the proposed technique has been tested using various image datasets such as Yale, and extended Yale B under different environments such as illumination variation and 3D changes in facial expressions. The test results show that the proposed technique yields significantly better performance when compared to existing JTC-based face recognition techniques.

  17. Nonlinear channelizer.

    PubMed

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D; Leung, Daniel; Liu, Norman; Meadows, Brian K; Gordon, Frank; Bulsara, Adi R; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  18. Nonlinear channelizer

    NASA Astrophysics Data System (ADS)

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  19. Effective indexing for face recognition

    NASA Astrophysics Data System (ADS)

    Sochenkov, I.; Sochenkova, A.; Vokhmintsev, A.; Makovetskii, A.; Melnikov, A.

    2016-09-01

    Face recognition is one of the most important tasks in computer vision and pattern recognition. Face recognition is useful for security systems to provide safety. In some situations it is necessary to identify the person among many others. In this case this work presents new approach in data indexing, which provides fast retrieval in big image collections. Data indexing in this research consists of five steps. First, we detect the area containing face, second we align face, and then we detect areas containing eyes and eyebrows, nose, mouth. After that we find key points of each area using different descriptors and finally index these descriptors with help of quantization procedure. The experimental analysis of this method is performed. This paper shows that performing method has results at the level of state-of-the-art face recognition methods, but it is also gives results fast that is important for the systems that provide safety.

  20. Switchable topological phonon channels

    NASA Astrophysics Data System (ADS)

    Süsstrunk, Roman; Zimmermann, Philipp; Huber, Sebastian D.

    2017-01-01

    Guiding energy deliberately is one of the central elements in engineering and information processing. It is often achieved by designing specific transport channels in a suitable material. Topological metamaterials offer a way to construct stable and efficient channels of unprecedented versatility. However, due to their stability it can be tricky to terminate them or to temporarily shut them off without changing the material properties massively. While a lot of effort was put into realizing mechanical topological metamaterials, almost no works deal with manipulating their edge channels in sight of applications. Here, we take a step in this direction, by taking advantage of local symmetry breaking potentials to build a switchable topological phonon channel.

  1. Intracranial markers of conscious face perception in humans.

    PubMed

    Baroni, Fabiano; van Kempen, Jochem; Kawasaki, Hiroto; Kovach, Christopher K; Oya, Hiroyuki; Howard, Matthew A; Adolphs, Ralph; Tsuchiya, Naotsugu

    2017-09-04

    Investigations of the neural basis of consciousness have greatly benefited from protocols that involve the presentation of stimuli at perceptual threshold, enabling the assessment of the patterns of brain activity that correlate with conscious perception, independently of any changes in sensory input. However, the comparison between perceived and unperceived trials would be expected to reveal not only the core neural substrate of a particular conscious perception, but also aspects of brain activity that facilitate, hinder or tend to follow conscious perception. We take a step towards the resolution of these confounds by combining an analysis of neural responses observed during the presentation of faces partially masked by Continuous Flash Suppression, and those responses observed during the unmasked presentation of faces and other images in the same subjects. We employed multidimensional classifiers to decode physical properties of stimuli or perceptual states from spectrotemporal representations of electrocorticographic signals (1071 channels in 5 subjects). Neural activity in certain face responsive areas located in both the fusiform gyrus and in the lateral-temporal/inferior-parietal cortex discriminated seen vs. unseen faces in the masked paradigm and upright faces vs. other categories in the unmasked paradigm. However, only the former discriminated upright vs. inverted faces in the unmasked paradigm. Our results suggest a prominent role for the fusiform gyrus in the configural perception of faces, and possibly other objects that are holistically processed. More generally, we advocate comparative analysis of neural recordings obtained during different, but related, experimental protocols as a promising direction towards elucidating the functional specificities of the patterns of neural activation that accompany our conscious experiences. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Fabrication of circular microfluidic channels by combining mechanical micromilling and soft lithography.

    PubMed

    Wilson, Mary E; Kota, Nithyanand; Kim, YongTae; Wang, Yadong; Stolz, Donna B; LeDuc, Philip R; Ozdoganlar, O Burak

    2011-04-21

    The fabrication of microfluidic channels with complex three-dimensional (3D) geometries presents a major challenge to the field of microfluidics, because conventional lithography methods are mainly limited to rectangular cross-sections. In this paper, we demonstrate the use of mechanical micromachining to fabricate microfluidic channels with complex cross-sectional geometries. Micro-scale milling tools are first used to fabricate semi-circular patterns on planar metallic surfaces to create a master mold. The micromilled pattern is then transferred to polydimethylsiloxane (PDMS) through a two-step reverse molding process. Using these semi-circular PDMS channels, circular cross-sectioned microchannels are created by aligning and adhering two channels face-to-face. Straight and serpentine-shaped microchannels were fabricated, and the channel geometry and precision of the metallic master and PDMS molds were assessed through scanning electron microscopy and non-contact profilometry. Channel functionality was tested by perfusion of liquid through the channels. This work demonstrates that micromachining enabled soft lithography is capable of fabricating non-rectangular cross-section channels for microfluidic applications. We believe that this approach will be important for many fields from biomimetics and vascular engineering to microfabrication and microreactor technologies.

  3. Famous face recognition, face matching, and extraversion.

    PubMed

    Lander, Karen; Poyarekar, Siddhi

    2015-01-01

    It has been previously established that extraverts who are skilled at interpersonal interaction perform significantly better than introverts on a face-specific recognition memory task. In our experiment we further investigate the relationship between extraversion and face recognition, focusing on famous face recognition and face matching. Results indicate that more extraverted individuals perform significantly better on an upright famous face recognition task and show significantly larger face inversion effects. However, our results did not find an effect of extraversion on face matching or inverted famous face recognition.

  4. Face-to-face: Perceived personal relevance amplifies face processing

    PubMed Central

    Pittig, Andre; Schupp, Harald T.; Alpers, Georg W.

    2017-01-01

    Abstract The human face conveys emotional and social information, but it is not well understood how these two aspects influence face perception. In order to model a group situation, two faces displaying happy, neutral or angry expressions were presented. Importantly, faces were either facing the observer, or they were presented in profile view directed towards, or looking away from each other. In Experiment 1 (n = 64), face pairs were rated regarding perceived relevance, wish-to-interact, and displayed interactivity, as well as valence and arousal. All variables revealed main effects of facial expression (emotional > neutral), face orientation (facing observer > towards > away) and interactions showed that evaluation of emotional faces strongly varies with their orientation. Experiment 2 (n = 33) examined the temporal dynamics of perceptual-attentional processing of these face constellations with event-related potentials. Processing of emotional and neutral faces differed significantly in N170 amplitudes, early posterior negativity (EPN), and sustained positive potentials. Importantly, selective emotional face processing varied as a function of face orientation, indicating early emotion-specific (N170, EPN) and late threat-specific effects (LPP, sustained positivity). Taken together, perceived personal relevance to the observer—conveyed by facial expression and face direction—amplifies emotional face processing within triadic group situations. PMID:28158672

  5. Face-to-face: Perceived personal relevance amplifies face processing.

    PubMed

    Bublatzky, Florian; Pittig, Andre; Schupp, Harald T; Alpers, Georg W

    2017-05-01

    The human face conveys emotional and social information, but it is not well understood how these two aspects influence face perception. In order to model a group situation, two faces displaying happy, neutral or angry expressions were presented. Importantly, faces were either facing the observer, or they were presented in profile view directed towards, or looking away from each other. In Experiment 1 (n = 64), face pairs were rated regarding perceived relevance, wish-to-interact, and displayed interactivity, as well as valence and arousal. All variables revealed main effects of facial expression (emotional > neutral), face orientation (facing observer > towards > away) and interactions showed that evaluation of emotional faces strongly varies with their orientation. Experiment 2 (n = 33) examined the temporal dynamics of perceptual-attentional processing of these face constellations with event-related potentials. Processing of emotional and neutral faces differed significantly in N170 amplitudes, early posterior negativity (EPN), and sustained positive potentials. Importantly, selective emotional face processing varied as a function of face orientation, indicating early emotion-specific (N170, EPN) and late threat-specific effects (LPP, sustained positivity). Taken together, perceived personal relevance to the observer-conveyed by facial expression and face direction-amplifies emotional face processing within triadic group situations. © The Author (2017). Published by Oxford University Press.

  6. Virtual & Real Face to Face Teaching

    ERIC Educational Resources Information Center

    Teneqexhi, Romeo; Kuneshka, Loreta

    2016-01-01

    In traditional "face to face" lessons, during the time the teacher writes on a black or white board, the students are always behind the teacher. Sometimes, this happens even in the recorded lesson in videos. Most of the time during the lesson, the teacher shows to the students his back not his face. We do not think the term "face to…

  7. Stepped nozzle

    DOEpatents

    Sutton, G.P.

    1998-07-14

    An insert is described which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment. 5 figs.

  8. Stepped nozzle

    DOEpatents

    Sutton, George P.

    1998-01-01

    An insert which allows a supersonic nozzle of a rocket propulsion system to operate at two or more different nozzle area ratios. This provides an improved vehicle flight performance or increased payload. The insert has significant advantages over existing devices for increasing nozzle area ratios. The insert is temporarily fastened by a simple retaining mechanism to the aft end of the diverging segment of the nozzle and provides for a multi-step variation of nozzle area ratio. When mounted in place, the insert provides the nozzle with a low nozzle area ratio. During flight, the retaining mechanism is released and the insert ejected thereby providing a high nozzle area ratio in the diverging nozzle segment.

  9. Face adaptation depends on seeing the face.

    PubMed

    Moradi, Farshad; Koch, Christof; Shimojo, Shinsuke

    2005-01-06

    Retinal input that is suppressed from visual awareness can nevertheless produce measurable aftereffects, revealing neural processes that do not directly result in a conscious percept. We here report that the face identity-specific aftereffect requires a visible face; it is effectively cancelled by binocular suppression or by inattentional blindness of the inducing face. Conversely, the same suppression does not interfere with the orientation-specific aftereffect. Thus, the competition between incompatible or interfering visual inputs to reach awareness is resolved before those aspects of information that are exploited in face identification are processed. We also found that the face aftereffect remained intact when the visual distracters in the inattention experiment were replaced with auditory distracters. Thus, cross-modal or cognitive interference that does not affect the visibility of the face does not interfere with the face aftereffect. We conclude that adaptation to face identity depends on seeing the face.

  10. Robust Face Detection from Still Images

    DTIC Science & Technology

    2014-01-01

    detection methodology, which consists of histogram analysis, Haar wavelet transformation and Adaboost learning techniques, is proposed. The extended...contact nature. However, due to the complexities of a human face , detecting a face in an image, the first step to perform facial recognition , is by no...performance of current face detection and expression recognition systems tends to be much lower when applied to individuals with dark skin”. This

  11. Robust Face Image Matching under Illumination Variations

    NASA Astrophysics Data System (ADS)

    Yang, Chyuan-Huei Thomas; Lai, Shang-Hong; Chang, Long-Wen

    2004-12-01

    Face image matching is an essential step for face recognition and face verification. It is difficult to achieve robust face matching under various image acquisition conditions. In this paper, a novel face image matching algorithm robust against illumination variations is proposed. The proposed image matching algorithm is motivated by the characteristics of high image gradient along the face contours. We define a new consistency measure as the inner product between two normalized gradient vectors at the corresponding locations in two images. The normalized gradient is obtained by dividing the computed gradient vector by the corresponding locally maximal gradient magnitude. Then we compute the average consistency measures for all pairs of the corresponding face contour pixels to be the robust matching measure between two face images. To alleviate the problem due to shadow and intensity saturation, we introduce an intensity weighting function for each individual consistency measure to form a weighted average of the consistency measure. This robust consistency measure is further extended to integrate multiple face images of the same person captured under different illumination conditions, thus making our robust face matching algorithm. Experimental results of applying the proposed face image matching algorithm on some well-known face datasets are given in comparison with some existing face recognition methods. The results show that the proposed algorithm consistently outperforms other methods and achieves higher than 93% recognition rate with three reference images for different datasets under different lighting conditions.

  12. Face recognition from a moving platform via sparse representation

    NASA Astrophysics Data System (ADS)

    Hsu, Ming Kai; Hsu, Charles; Lee, Ting N.; Szu, Harold

    2012-06-01

    A video-based surveillance system for passengers includes face detection, face tracking and face recognition. In general, the final recognition result of the video-based surveillance system is usually determined by the cumulative recognition results. Under this strategy, the correctness of face tracking plays an important role for the system recognition rate. For face tracking, the challenges of face tracking on a moving platform are that the space and time information used for conventional face tracking algorithms may be lost. Consequently, conventional face tracking algorithms can barely handle the face tracking on a moving platform. In this paper, we have verified the state-of-the-art technologies for face detection, face tracking and face recognition on a moving platform. In the mean time, we also proposed a new strategy for face tracking on a moving platform or face tracking under very low frame rate. The steps of the new strategy for face detection are: (1) classification the detected faces over a certain period instead of every frame (2) Tracking of each passenger is equivalent to reconstruct the time order of certain period for each passenger. If the cumulative recognition results are the only part needed for the surveillance system, step 2 can be skipped. In addition, if the additional information from the passengers is required, such as path tracking, lip read, gesture recognition, etc, time order reconstruction in step 2 can offer the information required.

  13. A Face Inversion Effect without a Face

    ERIC Educational Resources Information Center

    Brandman, Talia; Yovel, Galit

    2012-01-01

    Numerous studies have attributed the face inversion effect (FIE) to configural processing of internal facial features in upright but not inverted faces. Recent findings suggest that face mechanisms can be activated by faceless stimuli presented in the context of a body. Here we asked whether faceless stimuli with or without body context may induce…

  14. A Face Inversion Effect without a Face

    ERIC Educational Resources Information Center

    Brandman, Talia; Yovel, Galit

    2012-01-01

    Numerous studies have attributed the face inversion effect (FIE) to configural processing of internal facial features in upright but not inverted faces. Recent findings suggest that face mechanisms can be activated by faceless stimuli presented in the context of a body. Here we asked whether faceless stimuli with or without body context may induce…

  15. Mapping Teacher-Faces

    ERIC Educational Resources Information Center

    Thompson, Greg; Cook, Ian

    2013-01-01

    This paper uses Deleuze and Guattari's concept of faciality to analyse the teacher's face. According to Deleuze and Guattari, the teacher-face is a special type of face because it is an "overcoded" face produced in specific landscapes. This paper suggests four limit-faces for teacher faciality that actualise different mixes of significance and…

  16. Learning Faces from Photographs

    ERIC Educational Resources Information Center

    Longmore, Christopher A.; Liu, Chang Hong; Young, Andrew W.

    2008-01-01

    Previous studies examining face learning have mostly used only a single exposure to 1 image of each of the faces to be learned. However, in daily life, faces are usually learned from multiple encounters. These 6 experiments examined the effects on face learning of repeated exposures to single or multiple images of a face. All experiments…

  17. Learning Faces from Photographs

    ERIC Educational Resources Information Center

    Longmore, Christopher A.; Liu, Chang Hong; Young, Andrew W.

    2008-01-01

    Previous studies examining face learning have mostly used only a single exposure to 1 image of each of the faces to be learned. However, in daily life, faces are usually learned from multiple encounters. These 6 experiments examined the effects on face learning of repeated exposures to single or multiple images of a face. All experiments…

  18. Mapping Teacher-Faces

    ERIC Educational Resources Information Center

    Thompson, Greg; Cook, Ian

    2013-01-01

    This paper uses Deleuze and Guattari's concept of faciality to analyse the teacher's face. According to Deleuze and Guattari, the teacher-face is a special type of face because it is an "overcoded" face produced in specific landscapes. This paper suggests four limit-faces for teacher faciality that actualise different mixes of significance and…

  19. Numerical modeling of turbulent flow in a channel

    NASA Technical Reports Server (NTRS)

    Dai, Y. W.; Ghoniem, A. F.; Sherman, F. S.; Oppenheim, A. K.

    1983-01-01

    Two-dimensional incompressible turbulent flow in a channel with a backward-facing step was studied numerically by Chorin's Random Vortex Method (RVM), an algorithm capable of tracing the action of elementary turbulent eddies and their cumulative effects without imposing any restrictions upon their motions. The step occurs in one side of a channel with otherwise flat, parallel walls; its height equals 1/3, 1/4 or 1/5 the width of the channel downstream. The main objective was to investigate the behavior of the large-scale turbulent eddies in a flow and the flow characteristics in the separated shear layer, the reattached zone, and the rebuilding boundary layer after reattachment. The unsteady vorticity field and the distribution of time-averaged turbulent statistics were obtained. The effects of expansion step height and initial boundary layer state were also studied. Comparisons were made with the available experimental results. The agreement is satisfactory in the velocity profiles and in the reattachment length, and fairly good in the turbulence profiles. Also a mechanism of the development of the reattaching turbulent flow was suggested by the numerical results.

  20. Electrophysiological correlates of masked face priming

    PubMed Central

    Henson, R.N.; Mouchlianitis, E.; Matthews, W.J.; Kouider, S.

    2008-01-01

    Using a sandwich-masked priming paradigm with faces, we report two ERP effects that appear to reflect different levels of subliminal face processing. These two ERP repetition effects dissociate in their onset, scalp topography, and sensitivity to face familiarity. The “early” effect occurred between 100 and 150 ms, was maximally negative-going over lateral temporoparietal channels, and was found for both familiar and unfamiliar faces. The “late” effect occurred between 300 and 500 ms, was maximally positive-going over centroparietal channels, and was found only for familiar faces. The early effect resembled our previous fMRI data from the same paradigm; the late effect resembled the behavioural priming found, in the form of faster reaction times to make fame judgments about primed relative to unprimed familiar faces. None of the ERP or behavioural effects appeared explicable by a measure of participants’ ability to see the primes. The ERP and behavioural effects showed some sensitivity to whether the same or a different photograph of a face was repeated, but could remain reliable across different photographs, and did not appear attributable to a low-level measure of pixelwise overlap between prime and probe photograph. The functional significance of these ERP effects is discussed in relation to unconscious perception and face processing. PMID:18234522

  1. Dislocation etching of rough crystal faces

    NASA Astrophysics Data System (ADS)

    Van Enckevort, W. J. P.; Smet, F.

    1988-07-01

    A model for the preferential dissolution near the outcrops of dislocations at rough (K, S or F faces above the roughening temperature) crystal faces has been developed. In contrast to F faces below the roughening transition, no lateral flow of steps from the etched dislocation centre occurs and therefore only small etch pits, either not or only barely visible by optical microscopy are expected to be formed. This was confirmed by etching of K, S and F faces of Bi 4(GeO 4) 3, KH 2PO 4 and potash alum crystals.

  2. Lava Channels

    NASA Image and Video Library

    2013-12-03

    The channels and linear depression in this image captured by NASA 2001 Mars Odyssey spacecraft are located on the western margin of the Elysium Volcanic complex. The channels were created by lava flow.

  3. Experimental Study of Supersonic Flow over a forward Facing Step

    NASA Astrophysics Data System (ADS)

    Jayaprakash Narayan, M.; Govardhan, Raghuraman N.

    In supersonic vehicles, it is necessary to decelerate the intake air to subsonic speed for combustion. This is typically achieved by a series of oblique shocks[1]. In these air intakes, the oblique shock wave interacts with the boundary layer on the surface

  4. Facing facts: neuronal mechanisms of face perception.

    PubMed

    Dekowska, Monika; Kuniecki, Michał; Jaśkowski, Piotr

    2008-01-01

    The face is one of the most important stimuli carrying social meaning. Thanks to the fast analysis of faces, we are able to judge physical attractiveness and features of their owners' personality, intentions, and mood. From one's facial expression we can gain information about danger present in the environment. It is obvious that the ability to process efficiently one's face is crucial for survival. Therefore, it seems natural that in the human brain there exist structures specialized for face processing. In this article, we present recent findings from studies on the neuronal mechanisms of face perception and recognition in the light of current theoretical models. Results from brain imaging (fMRI, PET) and electrophysiology (ERP, MEG) show that in face perception particular regions (i.e. FFA, STS, IOA, AMTG, prefrontal and orbitofrontal cortex) are involved. These results are confirmed by behavioral data and clinical observations as well as by animal studies. The developmental findings reviewed in this article lead us to suppose that the ability to analyze face-like stimuli is hard-wired and improves during development. Still, experience with faces is not sufficient for an individual to become an expert in face perception. This thesis is supported by the investigation of individuals with developmental disabilities, especially with autistic spectrum disorders (ASD).

  5. Attention Capture by Faces

    ERIC Educational Resources Information Center

    Langton, Stephen R. H.; Law, Anna S.; Burton, A. Mike; Schweinberger, Stefan R.

    2008-01-01

    We report three experiments that investigate whether faces are capable of capturing attention when in competition with other non-face objects. In Experiment 1a participants took longer to decide that an array of objects contained a butterfly target when a face appeared as one of the distracting items than when the face did not appear in the array.…

  6. Attention Capture by Faces

    ERIC Educational Resources Information Center

    Langton, Stephen R. H.; Law, Anna S.; Burton, A. Mike; Schweinberger, Stefan R.

    2008-01-01

    We report three experiments that investigate whether faces are capable of capturing attention when in competition with other non-face objects. In Experiment 1a participants took longer to decide that an array of objects contained a butterfly target when a face appeared as one of the distracting items than when the face did not appear in the array.…

  7. A multistep approach for infrared face recognition in texture space

    NASA Astrophysics Data System (ADS)

    Akhloufi, Moulay A.; Bendada, Abdelhakim

    2013-05-01

    Face recognition is an area of computer vision that has attracted a lot of interest from the research community. A growing demand for robust face recognition in security applications has driven interesting advancements in this field. In this work, we introduce a new multistep approach for face recognition in the infrared spectrum. The proposed approach works in texture space using binary and ternary pattern descriptors. The approach operates in two steps. In the first step, dimensionality reduction techniques are used to classify the preprocessed infrared face image. This operation permits the selection of the highest score candidates. In the second step, a small set of these candidates are then classified using a correlation based approach. This last step permits the selection of the best matching candidate. The obtained results show a high increase in the face recognition performance when a multistep approach is used compared to dimensionality reduction face recognition techniques alone.

  8. Familiar face + novel face = familiar face? Representational bias in the perception of morphed faces in chimpanzees

    PubMed Central

    Myowa-Yamakoshi, Masako

    2016-01-01

    Highly social animals possess a well-developed ability to distinguish the faces of familiar from novel conspecifics to induce distinct behaviors for maintaining society. However, the behaviors of animals when they encounter ambiguous faces of familiar yet novel conspecifics, e.g., strangers with faces resembling known individuals, have not been well characterised. Using a morphing technique and preferential-looking paradigm, we address this question via the chimpanzee’s facial–recognition abilities. We presented eight subjects with three types of stimuli: (1) familiar faces, (2) novel faces and (3) intermediate morphed faces that were 50% familiar and 50% novel faces of conspecifics. We found that chimpanzees spent more time looking at novel faces and scanned novel faces more extensively than familiar or intermediate faces. Interestingly, chimpanzees looked at intermediate faces in a manner similar to familiar faces with regards to the fixation duration, fixation count, and saccade length for facial scanning, even though the participant was encountering the intermediate faces for the first time. We excluded the possibility that subjects merely detected and avoided traces of morphing in the intermediate faces. These findings suggest a bias for a feeling-of-familiarity that chimpanzees perceive familiarity with an intermediate face by detecting traces of a known individual, as 50% alternation is sufficient to perceive familiarity. PMID:27602275

  9. Programmed versus Face-to-Face Counseling

    ERIC Educational Resources Information Center

    Gilbert, William M.; Ewing, Thomas N.

    1971-01-01

    A comparison was made of the effectiveness of a programmed Self-Counseling Manual and a normal precollege counseling interview by experienced counselors. Findings supported the use of programmed counseling as an adjunct to or substitute for face-to-face counseling. (Author)

  10. Programmed versus Face-to-Face Counseling

    ERIC Educational Resources Information Center

    Gilbert, William M.; Ewing, Thomas N.

    1971-01-01

    A comparison was made of the effectiveness of a programmed Self-Counseling Manual and a normal precollege counseling interview by experienced counselors. Findings supported the use of programmed counseling as an adjunct to or substitute for face-to-face counseling. (Author)

  11. TRP Channels

    PubMed Central

    Venkatachalam, Kartik; Montell, Craig

    2011-01-01

    The TRP (Transient Receptor Potential) superfamily of cation channels is remarkable in that it displays greater diversity in activation mechanisms and selectivities than any other group of ion channels. The domain organizations of some TRP proteins are also unusual, as they consist of linked channel and enzyme domains. A unifying theme in this group is that TRP proteins play critical roles in sensory physiology, which include contributions to vision, taste, olfaction, hearing, touch, and thermo- and osmosensation. In addition, TRP channels enable individual cells to sense changes in their local environment. Many TRP channels are activated by a variety of different stimuli and function as signal integrators. The TRP superfamily is divided into seven subfamilies: the five group 1 TRPs (TRPC, TRPV, TRPM, TRPN, and TRPA) and two group 2 subfamilies (TRPP and TRPML). TRP channels are important for human health as mutations in at least four TRP channels underlie disease. PMID:17579562

  12. 26. Central compression lock, north span facing north. Compression lock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. Central compression lock, north span facing north. Compression lock locks two spans together at highest point. There are three compression locks. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  13. 22. View of Clark Fork Vehicle Bridge facing downwest side. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. View of Clark Fork Vehicle Bridge facing down-west side. Looking at road deck and vertical laced channel. - Clark Fork Vehicle Bridge, Spanning Clark Fork River, serves Highway 200, Clark Fork, Bonner County, ID

  14. Appearance-based color face recognition with 3D model

    NASA Astrophysics Data System (ADS)

    Wang, Chengzhang; Bai, Xiaoming

    2013-03-01

    Appearance-based face recognition approaches explore color cues of face images, i.e. grey or color information for recognition task. They first encode color face images, and then extract facial features for classification. Similar to conventional singular value decomposition, hypercomplex matrix also exists singular value decomposition on hypercomplex field. In this paper, a novel color face recognition approach based on hypercomplex singular value decomposition is proposed. The approach employs hypercomplex to encode color face information of different channels simultaneously. Hypercomplex singular value decomposition is utilized then to compute the basis vectors of the color face subspace. To improve learning efficiency of the algorithm, 3D active deformable model is exploited to generate virtual face images. Color face samples are projected onto the subspace and projection coefficients are utilized as facial features. Experimental results on CMU PIE face database verify the effectiveness of the proposed approach.

  15. Insulated face brick

    SciTech Connect

    Cromrich, J.; Cromrich, L.B.

    1990-10-16

    This patent describes a method for forming insulated brick intended solely for use in building walls and having superior insulation qualities and lighter weight consonant with the load bearing capabilities of building bricks and the appearance of facing brick. It comprises dry mixing two parts of vermiculite and one part of brick clay, thereby forming a dry mixture having a vermiculite to clay ratio of approximately two-to-one by volume; adding water to the dry mixture and mixing, so that a substantially dry admixture having expanded vermiculite and brick clay is formed; forming a facing layer solely from brick clay; molding and compressing the substantially dry admixture, so as to form a generally rectangular main body layer having parallel top and bottom faces, a pair of parallel side faces and a pair of parallel end faces, respectively, the top and bottom faces being substantially larger in area than the respective side faces, and the side faces being substantially larger in area than the respective end faces, the body layer further having at least one bore formed therein, the bore running from the top face to the bottom face perpendicularly thereto and substantially parallel to the side surfaces thereof, the bore being substantially centrally disposed and wherein the facing layer is disposed on one of the side surfaces of the body portion; curing the molded admixture having the facing layer disposed thereon; whereby a cured brick is formed; and firing the cured brick and the facing layer disposed thereon, whereby an integral brick is formed having top and bottom faces of the brick which are entirely devoid of facing layers, wherein the brick has the desired load bearing capability substantially between its top and bottom faces, whereby the outer facing layer only provides the desired appearance and weather resistance, and further whereby the weight of the brick is substantially reduced.

  16. What makes faces special?

    PubMed

    Yue, Xiaomin; Tjan, Bosco S; Biederman, Irving

    2006-10-01

    What may be special about faces, compared to non-face objects, is that their neural representation may be fundamentally spatial, e.g., Gabor-like. Subjects matched a sequence of two filtered images, each containing every other combination of spatial frequency and orientation, of faces or non-face 3D blobs, judging whether the person or blob was the same or different. On a match trial, the images were either identical or complementary (containing the remaining spatial frequency and orientation content). Relative to an identical pair of images, a complementary pair of faces, but not blobs, reduced matching accuracy and released fMRI adaptation in the fusiform face area.

  17. A causal relationship between face-patch activity and face-detection behavior

    PubMed Central

    Sadagopan, Srivatsun; Zarco, Wilbert; Freiwald, Winrich A

    2017-01-01

    The primate brain contains distinct areas densely populated by face-selective neurons. One of these, face-patch ML, contains neurons selective for contrast relationships between face parts. Such contrast-relationships can serve as powerful heuristics for face detection. However, it is unknown whether neurons with such selectivity actually support face-detection behavior. Here, we devised a naturalistic face-detection task and combined it with fMRI-guided pharmacological inactivation of ML to test whether ML is of critical importance for real-world face detection. We found that inactivation of ML impairs face detection. The effect was anatomically specific, as inactivation of areas outside ML did not affect face detection, and it was categorically specific, as inactivation of ML impaired face detection while sparing body and object detection. These results establish that ML function is crucial for detection of faces in natural scenes, performing a critical first step on which other face processing operations can build. DOI: http://dx.doi.org/10.7554/eLife.18558.001 PMID:28375078

  18. Face to Face Communications in Space

    NASA Technical Reports Server (NTRS)

    Cohen, Malcolm M.; Davon, Bonnie P. (Technical Monitor)

    1999-01-01

    It has been reported that human face-to-face communications in space are compromised by facial edema, variations in the orientations of speakers and listeners, and background noises that are encountered in the shuttle and in space stations. To date, nearly all reports have been anecdotal or subjective, in the form of post-flight interviews or questionnaires; objective and quantitative data are generally lacking. Although it is acknowledged that efficient face-to-face communications are essential for astronauts to work safely and effectively, specific ways in which the space environment interferes with non-linguistic communication cues are poorly documented. Because we have only a partial understanding of how non-linguistic communication cues may change with mission duration, it is critically important to obtain objective data, and to evaluate these cues under well-controlled experimental conditions.

  19. Face to Face Communications in Space

    NASA Technical Reports Server (NTRS)

    Cohen, Malcolm M.; Davon, Bonnie P. (Technical Monitor)

    1999-01-01

    It has been reported that human face-to-face communications in space are compromised by facial edema, variations in the orientations of speakers and listeners, and background noises that are encountered in the shuttle and in space stations. To date, nearly all reports have been anecdotal or subjective, in the form of post-flight interviews or questionnaires; objective and quantitative data are generally lacking. Although it is acknowledged that efficient face-to-face communications are essential for astronauts to work safely and effectively, specific ways in which the space environment interferes with non-linguistic communication cues are poorly documented. Because we have only a partial understanding of how non-linguistic communication cues may change with mission duration, it is critically important to obtain objective data, and to evaluate these cues under well-controlled experimental conditions.

  20. Face hallucination using orthogonal canonical correlation analysis

    NASA Astrophysics Data System (ADS)

    Zhou, Huiling; Lam, Kin-Man

    2016-05-01

    A two-step face-hallucination framework is proposed to reconstruct a high-resolution (HR) version of a face from an input low-resolution (LR) face, based on learning from LR-HR example face pairs using orthogonal canonical correlation analysis (orthogonal CCA) and linear mapping. In the proposed algorithm, face images are first represented using principal component analysis (PCA). Canonical correlation analysis (CCA) with the orthogonality property is then employed, to maximize the correlation between the PCA coefficients of the LR and the HR face pairs to improve the hallucination performance. The original CCA does not own the orthogonality property, which is crucial for information reconstruction. We propose using orthogonal CCA, which is proven by experiments to achieve a better performance in terms of global face reconstruction. In addition, in the residual-compensation process, a linear-mapping method is proposed to include both the inter- and intrainformation about manifolds of different resolutions. Compared with other state-of-the-art approaches, the proposed framework can achieve a comparable, or even better, performance in terms of global face reconstruction and the visual quality of face hallucination. Experiments on images with various parameter settings and blurring distortions show that the proposed approach is robust and has great potential for real-world applications.

  1. Face recognition with intensified NIR imagery

    NASA Astrophysics Data System (ADS)

    Socolinsky, Diego A.; Wolff, Lawrence B.; Lundberg, Andrew J.

    2006-04-01

    This paper presents a systematic study of face recognition performance as a function of light level using intensified near infrared imagery. This technology is the most prevalent in both civilian and military night vision equipment, and provides enough intensification for human operators to perform standard tasks under extremely low-light conditions. We describe a comprehensive data collection effort undertaken by the authors to image subjects under carefully controlled illumination and quantify the performance of standard face recognition algorithms on visible and intensified imagery as a function of light level. Performance comparisons for automatic face recognition are reported using the standardized implementations from the CSU Face Identification Evaluation System. The results contained in this paper should constitute the initial step for analysis and deployment of face recognition systems designed to work in low-light level conditions.

  2. TRP channels and pain.

    PubMed

    Julius, David

    2013-01-01

    Nociception is the process whereby primary afferent nerve fibers of the somatosensory system detect noxious stimuli. Pungent irritants from pepper, mint, and mustard plants have served as powerful pharmacological tools for identifying molecules and mechanisms underlying this initial step of pain sensation. These natural products have revealed three members of the transient receptor potential (TRP) ion channel family--TRPV1, TRPM8, and TRPA1--as molecular detectors of thermal and chemical stimuli that activate sensory neurons to produce acute or persistent pain. Analysis of TRP channel function and expression has validated the existence of nociceptors as a specialized group of somatosensory neurons devoted to the detection of noxious stimuli. These studies are also providing insight into the coding logic of nociception and how specification of nociceptor subtypes underlies behavioral discrimination of noxious thermal, chemical, and mechanical stimuli. Biophysical and pharmacological characterization of these channels has provided the intellectual and technical foundation for developing new classes of analgesic drugs.

  3. Acoustic imaging of the passage of turbidity currents and associated hydraulic jumps on underlying cyclic step bedforms. Squamish, BC

    NASA Astrophysics Data System (ADS)

    Hughes Clarke, J. E.

    2013-12-01

    Active channelized turbidity currents have been repeatedly imaged in 60m of water on the Squamish prodelta. Previously in 2011 and 2012, the prodelta has been repetitively surveyed on daily and hourly timescales and is thus known to exhibit trains of bedforms along the channel floors that resemble cyclic steps that migrate upslope intermittently. Beyond the channel mouths, clear turbidity current flows had previously been detected using a seabed mounted ADCP. In order to directly observe the passage of the flow in the channelized section of the prodelta, in June 2013 a vessel was moored using 4 anchors directly above one of the channels. The vessel operated two hull-mounted single beam sonars at 28 and 200 kHz and a multibeam sonar at 95 kHz, all imaging a near stationary point or swath within or across the channel. In addition a 1200 kHz ADCP was suspended 12m above the seabed and two 500 kHz imaging multibeams were suspended 10m above the channel floor. One of the suspended multibeams was oriented facing upslope examining a 150m range, 120 degree, plan view sector of the channel. The second suspended multibeam was oriented downward to derive a ~30m long along-track section over the length of one of the bedforms. A mechanically dipped CTD and optical backscatter probe was lower repeatedly directly into the active flows until it touched the seabed at about one minute periods. Over a period of 5 days, between 1 and 7 discrete flows per day were monitored passing by within one hour of low water. Their head velocities ranged from ~ 0.5 to 2.5m/s and their thicknesses were generally in the 3-5m range. Looking upstream in plan view, the lobate head of the approaching flows could be seen to be constricted to specific talwegs within the channel floor and rise up and over successive cyclic step bedforms. The higher velocity flows exhibit clear turbulent eddies on their upper surface. The duration of the high velocity component of the flow rarely lasted for more than a few

  4. TRP Channels

    NASA Astrophysics Data System (ADS)

    Voets, Thomas; Owsianik, Grzegorz; Nilius, Bernd

    The TRP superfamily represents a highly diverse group of cation-permeable ion channels related to the product of the Drosophila trp (transient receptor potential) gene. The cloning and characterization of members of this cation channel family has experienced a remarkable growth during the last decade, uncovering a wealth of information concerning the role of TRP channels in a variety of cell types, tissues, and species. Initially, TRP channels were mainly considered as phospholipase C (PLC)-dependent and/or store-operated Ca2+-permeable cation channels. More recent research has highlighted the sensitivity of TRP channels to a broad array of chemical and physical stimuli, allowing them to function as dedicated biological sensors involved in processes ranging from vision to taste, tactile sensation, and hearing. Moreover, the tailored selectivity of certain TRP channels enables them to play key roles in the cellular uptake and/or transepithelial transport of Ca2+, Mg2+, and trace metal ions. In this chapter we give a brief overview of the TRP channel superfamily followed by a survey of current knowledge concerning their structure and activation mechanisms.

  5. Rippley Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    18 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a narrow channel on the upper east flank of the martian volcano, Hadriaca Patera. Because it is located on a volcano, most likely this channel was formed by lava, perhaps as a lava tube at which the thin roof later collapsed. Large ripples of windblown sediment now occur on the channel floor; their crests are generally perpendicular to the channel walls, suggesting that winds blow up and down through this channel.

    Location near: 30.5oS, 266.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  6. Rippley Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    18 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a narrow channel on the upper east flank of the martian volcano, Hadriaca Patera. Because it is located on a volcano, most likely this channel was formed by lava, perhaps as a lava tube at which the thin roof later collapsed. Large ripples of windblown sediment now occur on the channel floor; their crests are generally perpendicular to the channel walls, suggesting that winds blow up and down through this channel.

    Location near: 30.5oS, 266.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  7. Energy efficient face seal

    NASA Technical Reports Server (NTRS)

    Sehnal, J.; Sedy, J.; Etsion, I.; Zobens, A.

    1982-01-01

    Torque, face temperature, leakage, and wear of a flat face seal were compared with three coned face seals at pressures up to 2758 kPa and speeds up to 8000 rpm. Axial movement of the mating seal parts was recorded by a digital data acquisition system. The coning of the tungsten carbide primary ring ranged from .51 micro-m to 5.6 micro-m. The torque of the coned face seal balanced to 76.3% was an average 42% lower, the leakage eleven times higher, than that of the standard flat face seal. The reduction of the balance of the coned face seal to 51.3% resulted by decreasing the torque by an additional 44% and increasing leakage 12 to 230 times, depending on the seal shaft speed. No measurable wear was observed on the face of the coned seals.

  8. Face Time: Educating Face Transplant Candidates

    PubMed Central

    Lamparello, Brooke M.; Bueno, Ericka M.; Diaz-Siso, Jesus Rodrigo; Sisk, Geoffroy C.; Pomahac, Bohdan

    2013-01-01

    Objective: Face transplantation is the innovative application of microsurgery and immunology to restore appearance and function to those with severe facial disfigurements. Our group aims to establish a multidisciplinary education program that can facilitate informed consent and build a strong knowledge base in patients to enhance adherence to medication regimes, recovery, and quality of life. Methods: We analyzed handbooks from our institution's solid organ transplant programs to identify topics applicable to face transplant patients. The team identified unique features of face transplantation that warrant comprehensive patient education. Results: We created a 181-page handbook to provide subjects interested in pursuing transplantation with a written source of information on the process and team members and to address concerns they may have. While the handbook covers a wide range of topics, it is easy to understand and visually appealing. Conclusions: Face transplantation has many unique aspects that must be relayed to the patients pursuing this novel therapy. Since candidates lack third-party support groups and programs, the transplant team must provide an extensive educational component to enhance this complex process. Practice Implications: As face transplantation continues to develop, programs must create sound education programs that address patients’ needs and concerns to facilitate optimal care. PMID:23861990

  9. Ligand-bound structures of 3-deoxy-D-manno-octulosonate 8-phosphate phosphatase from Moraxella catarrhalis reveal a water channel connecting to the active site for the second step of catalysis.

    PubMed

    Dhindwal, Sonali; Priyadarshini, Priyanka; Patil, Dipak N; Tapas, Satya; Kumar, Pramod; Tomar, Shailly; Kumar, Pravindra

    2015-02-01

    KdsC, the third enzyme of the 3-deoxy-D-manno-octulosonic acid (KDO) biosynthetic pathway, catalyzes a substrate-specific reaction to hydrolyze 3-deoxy-D-manno-octulosonate 8-phosphate to generate a molecule of KDO and phosphate. KdsC is a phosphatase that belongs to the C0 subfamily of the HAD superfamily. To understand the molecular basis for the substrate specificity of this tetrameric enzyme, the crystal structures of KdsC from Moraxella catarrhalis (Mc-KdsC) with several combinations of ligands, namely metal ion, citrate and products, were determined. Various transition states of the enzyme have been captured in these crystal forms. The ligand-free and ligand-bound crystal forms reveal that the binding of ligands does not cause any specific conformational changes in the active site. However, the electron-density maps clearly showed that the conformation of KDO as a substrate is different from the conformation adopted by KDO when it binds as a cleaved product. Furthermore, structural evidence for the existence of an intersubunit tunnel has been reported for the first time in the C0 subfamily of enzymes. A role for this tunnel in transferring water molecules from the interior of the tetrameric structure to the active-site cleft has been proposed. At the active site, water molecules are required for the formation of a water bridge that participates as a proton shuttle during the second step of the two-step phosphoryl-transfer reaction. In addition, as the KDO biosynthesis pathway is a potential antibacterial target, pharmacophore-based virtual screening was employed to identify inhibitor molecules for the Mc-KdsC enzyme.

  10. The elementary steps of the photodissociation and recombination reactions of iodine molecules enclosed in cages and channels of zeolite crystals: A femtosecond time-resolved study of the geometry effect

    NASA Astrophysics Data System (ADS)

    Flachenecker, G.; Materny, A.

    2004-03-01

    We present femtosecond time-resolved pump-probe experiments on iodine molecules enclosed into well-defined cages and channels of different crystalline SiO2 modifications of zeolites. The new experimental results obtained from iodine in TON (Silica-ZSM-22), FER (Silica-Ferrierit), and MFI (Silicalit-1) porosils are compared with data published earlier on the iodine/DDR (Decadodecasil 3R) porosil system [Flachenecker et al., Phys. Chem. Chem. Phys. 5, 865 (2003)]. A summary of all findings is given. The processes analyzed by means of the ultrafast spectroscopy are the vibrational relaxation as well as the dissociation and recombination reactions, which are caused by the interaction of the photo-excited iodine molecules with the cavity walls of the porosils. A clear dependence of the observed dynamics on the geometry of the surrounding lattice structure can be seen. These measurements are supported by temperature-dependent experiments. Making use of a theoretical model which is based on the classical Langevin equation, an analysis of the geometry-reaction relation is performed. The Brownian dynamics simulations show that in contrast to the vibrational relaxation the predissociation dynamics are independent of the frequency of collisions with the surroundings. From the results obtained in the different surroundings, we conclude that mainly local fields are responsible for the crossing from the bound B state to the repulsive a/a' states of the iodine molecules.

  11. MEMS in microfluidic channels.

    SciTech Connect

    Ashby, Carol Iris Hill; Okandan, Murat; Michalske, Terry A.; Sounart, Thomas L.; Matzke, Carolyn M.

    2004-03-01

    Microelectromechanical systems (MEMS) comprise a new class of devices that include various forms of sensors and actuators. Recent studies have shown that microscale cantilever structures are able to detect a wide range of chemicals, biomolecules or even single bacterial cells. In this approach, cantilever deflection replaces optical fluorescence detection thereby eliminating complex chemical tagging steps that are difficult to achieve with chip-based architectures. A key challenge to utilizing this new detection scheme is the incorporation of functionalized MEMS structures within complex microfluidic channel architectures. The ability to accomplish this integration is currently limited by the processing approaches used to seal lids on pre-etched microfluidic channels. This report describes Sandia's first construction of MEMS instrumented microfluidic chips, which were fabricated by combining our leading capabilities in MEMS processing with our low-temperature photolithographic method for fabricating microfluidic channels. We have explored in-situ cantilevers and other similar passive MEMS devices as a new approach to directly sense fluid transport, and have successfully monitored local flow rates and viscosities within microfluidic channels. Actuated MEMS structures have also been incorporated into microfluidic channels, and the electrical requirements for actuation in liquids have been quantified with an elegant theory. Electrostatic actuation in water has been accomplished, and a novel technique for monitoring local electrical conductivities has been invented.

  12. ``Just Another Distribution Channel?''

    NASA Astrophysics Data System (ADS)

    Lemstra, Wolter; de Leeuw, Gerd-Jan; van de Kar, Els; Brand, Paul

    The telecommunications-centric business model of mobile operators is under attack due to technological convergence in the communication and content industries. This has resulted in a plethora of academic contributions on the design of new business models and service platform architectures. However, a discussion of the challenges that operators are facing in adopting these models is lacking. We assess these challenges by considering the mobile network as part of the value system of the content industry. We will argue that from the perspective of a content provider the mobile network is ‘just another’ distribution channel. Strategic options available for the mobile communication operators are to deliver an excellent distribution channel for content delivery or to move upwards in the value chain by becoming a content aggregator. To become a mobile content aggregator operators will have to develop or acquire complementary resources and capabilities. Whether this strategic option is sustainable remains open.

  13. Video face recognition against a watch list

    NASA Astrophysics Data System (ADS)

    Abbas, Jehanzeb; Dagli, Charlie K.; Huang, Thomas S.

    2007-10-01

    Due to a large increase in the video surveillance data recently in an effort to maintain high security at public places, we need more robust systems to analyze this data and make tasks like face recognition a realistic possibility in challenging environments. In this paper we explore a watch-list scenario where we use an appearance based model to classify query faces from low resolution videos into either a watch-list or a non-watch-list face. We then use our simple yet a powerful face recognition system to recognize the faces classified as watch-list faces. Where the watch-list includes those people that we are interested in recognizing. Our system uses simple feature machine algorithms from our previous work to match video faces against still images. To test our approach, we match video faces against a large database of still images obtained from a previous work in the field from Yahoo News over a period of time. We do this matching in an efficient manner to come up with a faster and nearly real-time system. This system can be incorporated into a larger surveillance system equipped with advanced algorithms involving anomalous event detection and activity recognition. This is a step towards more secure and robust surveillance systems and efficient video data analysis.

  14. What makes faces special?

    PubMed Central

    Yue, Xiaomin; Tjan, Bosco S.; Biederman, Irving

    2009-01-01

    What may be special about faces, compared to non-face objects, is that their neural representation may be fundamentally spatial, e.g., Gabor-like. Subjects matched a sequence of two filtered images, each containing every other combination of spatial frequency and orientation, of faces or non-face 3D blobs, judging whether the person or blob was the same or different. On a match trial, the images were either identical or complementary (containing the remaining spatial frequency and orientation content). Relative to an identical pair of images, a complementary pair of faces, but not blobs, reduced matching accuracy and released fMRI adaptation in the fusiform face area. PMID:16938328

  15. Step-Growth Polymerization.

    ERIC Educational Resources Information Center

    Stille, J. K.

    1981-01-01

    Following a comparison of chain-growth and step-growth polymerization, focuses on the latter process by describing requirements for high molecular weight, step-growth polymerization kinetics, synthesis and molecular weight distribution of some linear step-growth polymers, and three-dimensional network step-growth polymers. (JN)

  16. Stepping motor controller

    DOEpatents

    Bourret, S.C.; Swansen, J.E.

    1982-07-02

    A stepping motor is microprocessor controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  17. Stepping motor controller

    DOEpatents

    Bourret, Steven C.; Swansen, James E.

    1984-01-01

    A stepping motor is microprocessingly controlled by digital circuitry which monitors the output of a shaft encoder adjustably secured to the stepping motor and generates a subsequent stepping pulse only after the preceding step has occurred and a fixed delay has expired. The fixed delay is variable on a real-time basis to provide for smooth and controlled deceleration.

  18. Mechanosensitive Channels

    NASA Astrophysics Data System (ADS)

    Martinac, Boris

    Living cells are exposed to a variety of mechanical stimuli acting throughout the biosphere. The range of the stimuli extends from thermal molecular agitation to potentially destructive cell swelling caused by osmotic pressure gradients. Cellular membranes present a major target for these stimuli. To detect mechanical forces acting upon them cell membranes are equipped with mechanosensitive (MS) ion channels. Functioning as molecular mechanoelectrical transducers of mechanical forces into electrical and/or chemical intracellular signals these channels play a critical role in the physiology of mechanotransduction. Studies of prokaryotic MS channels and recent work on MS channels of eukaryotes have significantly increased our understanding of their gating mechanism, physiological functions, and evolutionary origins as well as their role in the pathology of disease.

  19. Channel catfish

    USDA-ARS?s Scientific Manuscript database

    This book chapter provides a comprehensive overview of channel catfish aquaculture. Sections include fish biology; commercial culture; culture facilities; production practices; water quality management; nutrition, feeding and feed formulation; infectious diseases; harvesting and processing; and the...

  20. Single Streptomyces lividans K+ Channels

    PubMed Central

    Heginbotham, Lise; LeMasurier, Meredith; Kolmakova-Partensky, Ludmilla; Miller, Christopher

    1999-01-01

    Basic electrophysiological properties of the KcsA K+ channel were examined in planar lipid bilayer membranes. The channel displays open-state rectification and weakly voltage-dependent gating. Tetraethylammonium blocking affinity depends on the side of the bilayer to which the blocker is added. Addition of Na+ to the trans chamber causes block of open-channel current, while addition to the cis side has no effect. Most striking is the activation of KcsA by protons; channel activity is observed only when the trans bilayer chamber is at low pH. To ascertain which side of the channel faces which chamber, residues with structurally known locations were mapped to defined sides of the bilayer. Mutation of Y82, an external residue, results in changes in tetraethylammonium affinity exclusively from the cis side. Channels with cysteine residues substituted at externally exposed Y82 or internally exposed Q119 are functionally modified by methanethiosulfonate reagents from the cis or trans chambers, respectively. Block by charybdotoxin, known to bind to the channel's external mouth, is observed only when the toxin is added to the cis side of channels mutated to be toxin sensitive. These results demonstrate unambiguously that the protonation sites linked to gating are on the intracellular portion of the KcsA protein. PMID:10498673

  1. Learning discriminant face descriptor.

    PubMed

    Lei, Zhen; Pietikäinen, Matti; Li, Stan Z

    2014-02-01

    Local feature descriptor is an important module for face recognition and those like Gabor and local binary patterns (LBP) have proven effective face descriptors. Traditionally, the form of such local descriptors is predefined in a handcrafted way. In this paper, we propose a method to learn a discriminant face descriptor (DFD) in a data-driven way. The idea is to learn the most discriminant local features that minimize the difference of the features between images of the same person and maximize that between images from different people. In particular, we propose to enhance the discriminative ability of face representation in three aspects. First, the discriminant image filters are learned. Second, the optimal neighborhood sampling strategy is soft determined. Third, the dominant patterns are statistically constructed. Discriminative learning is incorporated to extract effective and robust features. We further apply the proposed method to the heterogeneous (cross-modality) face recognition problem and learn DFD in a coupled way (coupled DFD or C-DFD) to reduce the gap between features of heterogeneous face images to improve the performance of this challenging problem. Extensive experiments on FERET, CAS-PEAL-R1, LFW, and HFB face databases validate the effectiveness of the proposed DFD learning on both homogeneous and heterogeneous face recognition problems. The DFD improves POEM and LQP by about 4.5 percent on LFW database and the C-DFD enhances the heterogeneous face recognition performance of LBP by over 25 percent.

  2. A special purpose knowledge-based face localization method

    NASA Astrophysics Data System (ADS)

    Hassanat, Ahmad; Jassim, Sabah

    2008-04-01

    This paper is concerned with face localization for visual speech recognition (VSR) system. Face detection and localization have got a great deal of attention in the last few years, because it is an essential pre-processing step in many techniques that handle or deal with faces, (e.g. age, face, gender, race and visual speech recognition). We shall present an efficient method for localization human's faces in video images captured on mobile constrained devices, under a wide variation in lighting conditions. We use a multiphase method that may include all or some of the following steps starting with image pre-processing, followed by a special purpose edge detection, then an image refinement step. The output image will be passed through a discrete wavelet decomposition procedure, and the computed LL sub-band at a certain level will be transformed into a binary image that will be scanned by using a special template to select a number of possible candidate locations. Finally, we fuse the scores from the wavelet step with scores determined by color information for the candidate location and employ a form of fuzzy logic to distinguish face from non-face locations. We shall present results of large number of experiments to demonstrate that the proposed face localization method is efficient and achieve high level of accuracy that outperforms existing general-purpose face detection methods.

  3. How Well Do Computer-Generated Faces Tap Face Expertise?

    PubMed

    Crookes, Kate; Ewing, Louise; Gildenhuys, Ju-Dith; Kloth, Nadine; Hayward, William G; Oxner, Matt; Pond, Stephen; Rhodes, Gillian

    2015-01-01

    The use of computer-generated (CG) stimuli in face processing research is proliferating due to the ease with which faces can be generated, standardised and manipulated. However there has been surprisingly little research into whether CG faces are processed in the same way as photographs of real faces. The present study assessed how well CG faces tap face identity expertise by investigating whether two indicators of face expertise are reduced for CG faces when compared to face photographs. These indicators were accuracy for identification of own-race faces and the other-race effect (ORE)-the well-established finding that own-race faces are recognised more accurately than other-race faces. In Experiment 1 Caucasian and Asian participants completed a recognition memory task for own- and other-race real and CG faces. Overall accuracy for own-race faces was dramatically reduced for CG compared to real faces and the ORE was significantly and substantially attenuated for CG faces. Experiment 2 investigated perceptual discrimination for own- and other-race real and CG faces with Caucasian and Asian participants. Here again, accuracy for own-race faces was significantly reduced for CG compared to real faces. However the ORE was not affected by format. Together these results signal that CG faces of the type tested here do not fully tap face expertise. Technological advancement may, in the future, produce CG faces that are equivalent to real photographs. Until then caution is advised when interpreting results obtained using CG faces.

  4. Face transplantation: Anesthetic challenges

    PubMed Central

    Dalal, Aparna

    2016-01-01

    Face transplantation is a complex vascular composite allotransplantation (VCA) surgery. It involves multiple types of tissue, such as bone, muscles, blood vessels, nerves to be transferred from the donor to the recipient as one unit. VCAs were added to the definition of organs covered by the Organ Procurement and Transplantation Network Final Rule and National Organ Transplant Act. Prior to harvest of the face from the donor, a tracheostomy is usually performed. The osteotomies and dissection of the midface bony skeleton may involve severe hemorrhagic blood loss often requiring transfusion of blood products. A silicon face mask created from the facial impression is used to reconstruct the face and preserve the donor’s dignity. The recipient airway management most commonly used is primary intubation of an existing tracheostoma with a flexometallic endotracheal tube. The recipient surgery usually averages to 19-20 h. Since the face is a very vascular organ, there is usually massive bleeding, both in the dissection phase as well as in the reperfusion phase. Prior to reperfusion, often, after one sided anastomosis of the graft, the contralateral side is allowed to bleed to get rid of the preservation solution and other additives. Intraoperative product replacement should be guided by laboratory values and point of care testing for coagulation and hemostasis. In face transplantation, bolus doses of pressors or pressor infusions have been used intraoperatively in several patients to manage hypotension. This article reviews the anesthetic considerations for management for face transplantation, and some of the perioperative challenges faced. PMID:28058213

  5. Social judgments from faces.

    PubMed

    Todorov, Alexander; Mende-Siedlecki, Peter; Dotsch, Ron

    2013-06-01

    People make rapid and consequential social judgments from minimal (non-emotional) facial cues. There has been rapid progress in identifying the perceptual basis of these judgments using data-driven, computational models. In contrast, our understanding of the neural underpinnings of these judgments is rather limited. Meta-analyses of neuroimaging studies find a wide range of seemingly inconsistent responses in the amygdala that co-vary with social judgments from faces. Guided by computational models of social judgments, these responses can be accounted by positing that the amygdala (and posterior face selective regions) tracks face typicality. Atypical faces, whether positively or negatively evaluated, elicit stronger responses in the amygdala. We conclude with the promise of data-driven methods for modeling neural responses to social judgments from faces. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Step by Step: Avoiding Spiritual Bypass in 12-Step Work

    ERIC Educational Resources Information Center

    Cashwell, Craig S.; Clarke, Philip B.; Graves, Elizabeth G.

    2009-01-01

    With spirituality as a cornerstone, 12-step groups serve a vital role in the recovery community. It is important for counselors to be mindful, however, of the potential for clients to be in spiritual bypass, which likely will undermine the recovery process.

  7. Face Recognition in Humans and Machines

    NASA Astrophysics Data System (ADS)

    O'Toole, Alice; Tistarelli, Massimo

    The study of human face recognition by psychologists and neuroscientists has run parallel to the development of automatic face recognition technologies by computer scientists and engineers. In both cases, there are analogous steps of data acquisition, image processing, and the formation of representations that can support the complex and diverse tasks we accomplish with faces. These processes can be understood and compared in the context of their neural and computational implementations. In this chapter, we present the essential elements of face recognition by humans and machines, taking a perspective that spans psychological, neural, and computational approaches. From the human side, we overview the methods and techniques used in the neurobiology of face recognition, the underlying neural architecture of the system, the role of visual attention, and the nature of the representations that emerges. From the computational side, we discuss face recognition technologies and the strategies they use to overcome challenges to robust operation over viewing parameters. Finally, we conclude the chapter with a look at some recent studies that compare human and machine performances at face recognition.

  8. Adaptive tracking of narrowband HF channel response

    NASA Astrophysics Data System (ADS)

    Arikan, F.; Arikan, O.

    2003-12-01

    Estimation of channel impulse response constitutes a first step in computation of scattering function, channel equalization, elimination of multipath, and optimum detection and identification of transmitted signals through the HF channel. Due to spatial and temporal variations, HF channel impulse response has to be estimated adaptively. Based on developed state-space and measurement models, an adaptive Kalman filter is proposed to track the HF channel variation in time. Robust methods of initialization and adaptively adjusting the noise covariance in the system dynamics are proposed. In simulated examples under good, moderate and poor ionospheric conditions, it is observed that the adaptive Kalman filter based channel estimator provides reliable channel estimates and can track the variation of the channel in time with high accuracy.

  9. Face Search at Scale.

    PubMed

    Wang, Dayong; Otto, Charles; Jain, Anil K

    2017-06-01

    Given the prevalence of social media websites, one challenge facing computer vision researchers is to devise methods to search for persons of interest among the billions of shared photos on these websites. Despite significant progress in face recognition, searching a large collection of unconstrained face images remains a difficult problem. To address this challenge, we propose a face search system which combines a fast search procedure, coupled with a state-of-the-art commercial off the shelf (COTS) matcher, in a cascaded framework. Given a probe face, we first filter the large gallery of photos to find the top- k most similar faces using features learned by a convolutional neural network. The k retrieved candidates are re-ranked by combining similarities based on deep features and those output by the COTS matcher. We evaluate the proposed face search system on a gallery containing 80 million web-downloaded face images. Experimental results demonstrate that while the deep features perform worse than the COTS matcher on a mugshot dataset (93.7 percent versus 98.6 percent TAR@FAR of 0.01 percent), fusing the deep features with the COTS matcher improves the overall performance ( 99.5 percent TAR@FAR of 0.01 percent). This shows that the learned deep features provide complementary information over representations used in state-of-the-art face matchers. On the unconstrained face image benchmarks, the performance of the learned deep features is competitive with reported accuracies. LFW database: 98.20 percent accuracy under the standard protocol and 88.03 percent TAR@FAR of 0.1 percent under the BLUFR protocol; IJB-A benchmark: 51.0 percent TAR@FAR of 0.1 percent (verification), rank 1 retrieval of 82.2 percent (closed-set search), 61.5 percent FNIR@FAR of 1 percent (open-set search). The proposed face search system offers an excellent trade-off between accuracy and scalability on galleries with millions of images. Additionally, in a face search experiment involving

  10. Size-invariant representation of face in infant brain: an fNIRS-adaptation study.

    PubMed

    Kobayashi, Megumi; Otsuka, Yumiko; Kanazawa, So; Yamaguchi, Masami K; Kakigi, Ryusuke

    2012-12-05

    We studied whether 5-month-old to 8-month-old infants process faces in a size-invariant manner by applying the fNIRS-adaptation paradigm used in our previous study. We used near-infrared spectroscopy to measure hemodynamic responses in the temporal regions of infants' brains during the repeated presentation of an identical face and different faces while changing the size of the faces. As a result, we found that (a) the hemodynamic responses in the channels around the T5 and T6 positions increased significantly during the presentation of different faces and (b) the hemodynamic responses in these channels showed attenuation to the presentation of the same face compared with the presentation of different faces even when the size of the faces altered. Our findings indicated that infants could show adaptation to the same face despite size alterations and that this processing occurred in the bilateral temporal areas.

  11. BRICK RETAINING WALL AND STEPS AT FRONT YARD OF CROATAN, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    BRICK RETAINING WALL AND STEPS AT FRONT YARD OF CROATAN, VIEW TOWARD GARDEN, FACING NORTHEAST - Overhills, Fort Bragg Military Reservation, Approximately 15 miles NW of Fayetteville, Overhills, Harnett County, NC

  12. INTERIOR VIEW OF THE LIVING ROOM. SHOWING THE STEPS UP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF THE LIVING ROOM. SHOWING THE STEPS UP TO THE DINING ROOM WITH IRON RAILING. VIEW FACING NORTHEAST. - Hickam Field, Officers' Housing Type F, 602 Beard Avenue, Honolulu, Honolulu County, HI

  13. 13. MASS OF POURED CONCRETE IN IRREGULAR STEPPED LAYERS AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. MASS OF POURED CONCRETE IN IRREGULAR STEPPED LAYERS AT THE BASE OF THE LEFT (EAST) BUTTRESS. CAMERA FACING SOUTHWEST. - Salinas Dam, Salinas River near Pozo Road, Santa Margarita, San Luis Obispo County, CA

  14. English Channel

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The cloud covered earthscape of Northern Europe demonstrates the difficulty of photographing this elusive subject from space. The English Channel (51.0N, 1.5E) separating the British Islands from Europe is in the center of the scene. The white cliffs of Dover on the SE coast of the UK, the Thames River estuary and a partial view of the city of London can be seen on the north side of the Channel while the Normandy coast of France is to the south.

  15. English Channel

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The cloud covered earthscape of Northern Europe demonstrates the difficulty of photographing this elusive subject from space. The English Channel (51.0N, 1.5E) separating the British Islands from Europe is in the center of the scene. The white cliffs of Dover on the SE coast of the UK, the Thames River estuary and a partial view of the city of London can be seen on the north side of the Channel while the Normandy coast of France is to the south.

  16. Voltage-gated Proton Channels

    PubMed Central

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  17. Dynamic Face Seal Arrangement

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher (Inventor)

    1999-01-01

    A radial face seal arrangement is disclosed comprising a stationary seal ring that is spring loaded against a seal seat affixed to a rotating shaft. The radial face seal arrangement further comprises an arrangement that not only allows for preloading of the stationary seal ring relative to the seal seat, but also provides for dampening yielding a dynamic seating response for the radial face seal arrangement. The overall seal system, especially regarding the selection of the material for the stationary seal ring, is designed to operate over a wide temperature range from below ambient up to 900 C.

  18. A Step Circuit Program.

    ERIC Educational Resources Information Center

    Herman, Susan

    1995-01-01

    Aerobics instructors can use step aerobics to motivate students. One creative method is to add the step to the circuit workout. By incorporating the step, aerobic instructors can accommodate various fitness levels. The article explains necessary equipment and procedures, describing sample stations for cardiorespiratory fitness, muscular strength,…

  19. A Step Circuit Program.

    ERIC Educational Resources Information Center

    Herman, Susan

    1995-01-01

    Aerobics instructors can use step aerobics to motivate students. One creative method is to add the step to the circuit workout. By incorporating the step, aerobic instructors can accommodate various fitness levels. The article explains necessary equipment and procedures, describing sample stations for cardiorespiratory fitness, muscular strength,…

  20. Gaze cueing by pareidolia faces

    PubMed Central

    Takahashi, Kohske; Watanabe, Katsumi

    2013-01-01

    Visual images that are not faces are sometimes perceived as faces (the pareidolia phenomenon). While the pareidolia phenomenon provides people with a strong impression that a face is present, it is unclear how deeply pareidolia faces are processed as faces. In the present study, we examined whether a shift in spatial attention would be produced by gaze cueing of face-like objects. A robust cueing effect was observed when the face-like objects were perceived as faces. The magnitude of the cueing effect was comparable between the face-like objects and a cartoon face. However, the cueing effect was eliminated when the observer did not perceive the objects as faces. These results demonstrated that pareidolia faces do more than give the impression of the presence of faces; indeed, they trigger an additional face-specific attentional process. PMID:25165505

  1. Analyzing Interactions by an IIS-Map-Based Method in Face-to-Face Collaborative Learning: An Empirical Study

    ERIC Educational Resources Information Center

    Zheng, Lanqin; Yang, Kaicheng; Huang, Ronghuai

    2012-01-01

    This study proposes a new method named the IIS-map-based method for analyzing interactions in face-to-face collaborative learning settings. This analysis method is conducted in three steps: firstly, drawing an initial IIS-map according to collaborative tasks; secondly, coding and segmenting information flows into information items of IIS; thirdly,…

  2. Analyzing Interactions by an IIS-Map-Based Method in Face-to-Face Collaborative Learning: An Empirical Study

    ERIC Educational Resources Information Center

    Zheng, Lanqin; Yang, Kaicheng; Huang, Ronghuai

    2012-01-01

    This study proposes a new method named the IIS-map-based method for analyzing interactions in face-to-face collaborative learning settings. This analysis method is conducted in three steps: firstly, drawing an initial IIS-map according to collaborative tasks; secondly, coding and segmenting information flows into information items of IIS; thirdly,…

  3. Head and face reconstruction

    MedlinePlus

    ... and facial skin. That is why sometimes a plastic surgeon (for skin and face) and a neurosurgeon ( ... Mosby; 2015:chap 24. McGrath MH, Pomerantz J. Plastic surgery. In: Townsend CM, Beauchamp RD, Evers BM, ...

  4. Future Faces of Physics

    NASA Astrophysics Data System (ADS)

    Sauncy, Toni

    2008-10-01

    In keeping with its commitment to help students transform themselves into contributing members of the professional physics community, the Society of Physics Students National Council began efforts aimed at addressing issued of diversity in physics several years ago. One of the projects stemming from these discussions is the adoption of a 2008 theme ``The Future Faces of Physics.'' With this theme, the council aims to raise visibility and focus on issues of student diversity in physics. The initiative included the distribution of ``Future Faces of Physics Kits'' to any chapter hosting zone meetings. A highlight of the kit is the Future Faces of Physics Jeopardy set, which consists of buzzers, a score board, instructions, and a game board. The Future Faces of Physics game is a vehicle for generating discussion and raising awareness. The diversity session is hosted by the SPS Zone 13 and Zone 16 leadership.

  5. Accustomed to Her Face

    NASA Image and Video Library

    2007-06-26

    After nearly three years at Saturn, the Cassini spacecraft continues to observe the planet retinue of icy moons. Rhea cratered face attests to its great age, while its bright wisps hint at tectonic activity in the past

  6. Toward hyperspectral face recognition

    NASA Astrophysics Data System (ADS)

    Robila, Stefan A.

    2008-02-01

    Face recognition continues to meet significant challenges in reaching accurate results and still remains one of the activities where humans outperform technology. An attractive approach in improving face identification is provided by the fusion of multiple imaging sources such as visible and infrared images. Hyperspectral data, i.e. images collected over hundreds of narrow contiguous light spectrum intervals constitute a natural choice for expanding face recognition image fusion, especially since it may provide information beyond the normal visible range, thus exceeding the normal human sensing. In this paper we investigate the efficiency of hyperspectral face recognition through an in house experiment that collected data in over 120 bands within the visible and near infrared range. The imagery was produced using an off the shelf sensor in both indoors and outdoors with the subjects being photographed from various angles. Further processing included spectra collection and feature extraction. Human matching performance based on spectral properties is discussed.

  7. Protective Face Mask

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Mask to protect the physically impaired from injuries to the face and head has been developed by Langley Research Center. It is made of composite materials, usually graphite or boron fibers woven into a matrix. Weighs less than three ounces.

  8. Crystal growth kinetics of the two-step model

    NASA Astrophysics Data System (ADS)

    Tai, Clifford Y.; Lin, Chiu-Hsiung

    1987-03-01

    The single crystal technique was used to measure the growth rate of the potassium alum (111) face and the magnesium sulfate (110) face. The two-step model was found appropriate to describe the growth kinetics with the surface integration order of two for potassium alum crystal and of one for magnesium sulfate crystal. The individual rate constants, Kd and Kr, were determined accordingly.

  9. Modified drill permits one-step drilling operation

    NASA Technical Reports Server (NTRS)

    Libertone, C.

    1966-01-01

    Drill with modified cutting faces permits one-step drilling operation without chatter upon contact and premature wear. The modification of the drill, which has the same diameter as that of the desired hole, consists of a groove across the bottom of each of the cutting faces of the drill flutes.

  10. Discriminative Projection Selection Based Face Image Hashing

    NASA Astrophysics Data System (ADS)

    Karabat, Cagatay; Erdogan, Hakan

    Face image hashing is an emerging method used in biometric verification systems. In this paper, we propose a novel face image hashing method based on a new technique called discriminative projection selection. We apply the Fisher criterion for selecting the rows of a random projection matrix in a user-dependent fashion. Moreover, another contribution of this paper is to employ a bimodal Gaussian mixture model at the quantization step. Our simulation results on three different databases demonstrate that the proposed method has superior performance in comparison to previously proposed random projection based methods.

  11. Faces of root polytopes in all dimensions.

    PubMed

    Szajewska, Marzena

    2016-07-01

    In this paper the root polytopes of all finite reflection groups W with a connected Coxeter-Dynkin diagram in {\\bb R}^n are identified, their faces of dimensions 0 ≤ d ≤ n - 1 are counted, and the construction of representatives of the appropriate W-conjugacy class is described. The method consists of recursive decoration of the appropriate Coxeter-Dynkin diagram [Champagne et al. (1995). Can. J. Phys. 73, 566-584]. Each recursion step provides the essentials of faces of a specific dimension and specific symmetry. The results can be applied to crystals of any dimension and any symmetry.

  12. Recognizing one's own face.

    PubMed

    Kircher, T T; Senior, C; Phillips, M L; Rabe-Hesketh, S; Benson, P J; Bullmore, E T; Brammer, M; Simmons, A; Bartels, M; David, A S

    2001-01-01

    We report two studies of facial self-perception using individually tailored, standardized facial photographs of a group of volunteers and their partners. A computerized morphing procedure was used to merge each target face with an unknown control face. In the first set of experiments, a discrimination task revealed a delayed response time for the more extensively morphed self-face stimuli. In a second set of experiments, functional magnetic resonance imaging (fMRI) was used to measure brain activation while subjects viewed morphed versions of either their own or their partner's face, alternating in blocks with presentation of an unknown face. When subjects viewed themselves (minus activation for viewing an unknown face), increased blood oxygenation was detected in right limbic (hippocampal formation, insula, anterior cingulate), left prefrontal cortex and superior temporal cortex. In the partner (versus unknown) experiment, only the right insula was activated. We suggest that a neural network involving the right hemisphere in conjunction with left-sided associative and executive regions underlies the process of visual self-recognition. Together, this combination produces the unique experience of self-awareness.

  13. Step by step error assessment in braided river sediment budget using airborne LiDAR data

    NASA Astrophysics Data System (ADS)

    Lallias-Tacon, S.; Liébault, F.; Piégay, H.

    2014-06-01

    Sequential airborne LiDAR surveys were used to reconstruct the sediment budget of a 7-km-long braided river channel in southeastern France following a 14-year return period flood and to improve its accuracy step by step. Data processing involved (i) surface matching of the sequential point clouds, (ii) spatially distributed propagation of uncertainty based on surface conditions of the channel, and (iii) water depth subtraction from the digital elevation models based on water depths measured in the field. The respective influence of each processing step on sediment budget computation was systematically documented. This showed that surface matching and water depth subtraction both have a considerable effect on the net sediment budget. Although DEM of difference thresholding based on uncertainty analysis on absolute elevation values had a smaller effect on the sediment budget, this step is crucial for the production of a comprehensive map of channel deformations. A large independent data set of RTK-GPS checkpoints was used to control the quality of the LiDAR altimetry. The results showed that high density (7-9 points/m2) airborne LiDAR surveys can provide a very high level of detection of elevation changes on the exposed surfaces of the channel, with a 95% confidence interval level of detection between 19 and 30 cm. Change detection from LiDAR data revealed that 54% of the pre-flood active channel was reworked by the flood. The braided channel pattern was highly disturbed by the flood owing to the occurrence of several channel avulsions.

  14. Is Face Distinctiveness Gender Based?

    ERIC Educational Resources Information Center

    Baudouin, Jean-Yves; Gallay, Mathieu

    2006-01-01

    Two experiments were carried out to study the role of gender category in evaluations of face distinctiveness. In Experiment 1, participants had to evaluate the distinctiveness and the femininity-masculinity of real or artificial composite faces. The composite faces were created by blending either faces of the same gender (sexed composite faces,…

  15. Is Face Distinctiveness Gender Based?

    ERIC Educational Resources Information Center

    Baudouin, Jean-Yves; Gallay, Mathieu

    2006-01-01

    Two experiments were carried out to study the role of gender category in evaluations of face distinctiveness. In Experiment 1, participants had to evaluate the distinctiveness and the femininity-masculinity of real or artificial composite faces. The composite faces were created by blending either faces of the same gender (sexed composite faces,…

  16. Best Basis Selection Method Using Learning Weights for Face Recognition

    PubMed Central

    Lee, Wonju; Cheon, Minkyu; Hyun, Chang-Ho; Park, Mignon

    2013-01-01

    In the face recognition field, principal component analysis is essential to the reduction of the image dimension. In spite of frequent use of this analysis, it is commonly believed that the basis faces with large eigenvalues are chosen as the best subset in the nearest neighbor classifiers. We propose an alternative that can predict the classification error during the training steps and find the useful basis faces for the similarity metrics of the classical pattern algorithms. In addition, we also show the need for the eye-aligned dataset to have the pure face. The experiments using face images verify that our method reduces the negative effect on the misaligned face images and decreases the weights of the useful basis faces in order to improve the classification accuracy. PMID:24072026

  17. Locating faces in color photographs using neural networks

    NASA Astrophysics Data System (ADS)

    Brown, Joe R.; Talley, Jim

    1994-03-01

    This paper summarizes a research effort in finding the locations and sizes of faces in color images (photographs, video stills, etc.) if, in fact, faces are presented. Scenarios for using such a system include serving as the means of localizing skin for automatic color balancing during photo processing or it could be used as a front-end in a customs port of energy context for a system which identified persona non grata given a database of known faces. The approach presented here is a hybrid system including: a neural pre-processor, some conventional image processing steps, and a neural classifier as the final face/non-face discriminator. Neither the training (containing 17,655 faces) nor the test (containing 1829 faces) imagery databases were constrained in their content or quality. The results for the pilot system are reported along with a discussion for improving the current system.

  18. The channels of Mars

    NASA Technical Reports Server (NTRS)

    Baker, Victor R.

    1988-01-01

    The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

  19. The channels of Mars

    NASA Technical Reports Server (NTRS)

    Baker, Victor R.

    1988-01-01

    The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

  20. Successful Decoding of Famous Faces in the Fusiform Face Area

    PubMed Central

    Axelrod, Vadim; Yovel, Galit

    2015-01-01

    What are the neural mechanisms of face recognition? It is believed that the network of face-selective areas, which spans the occipital, temporal, and frontal cortices, is important in face recognition. A number of previous studies indeed reported that face identity could be discriminated based on patterns of multivoxel activity in the fusiform face area and the anterior temporal lobe. However, given the difficulty in localizing the face-selective area in the anterior temporal lobe, its role in face recognition is still unknown. Furthermore, previous studies limited their analysis to occipito-temporal regions without testing identity decoding in more anterior face-selective regions, such as the amygdala and prefrontal cortex. In the current high-resolution functional Magnetic Resonance Imaging study, we systematically examined the decoding of the identity of famous faces in the temporo-frontal network of face-selective and adjacent non-face-selective regions. A special focus has been put on the face-area in the anterior temporal lobe, which was reliably localized using an optimized scanning protocol. We found that face-identity could be discriminated above chance level only in the fusiform face area. Our results corroborate the role of the fusiform face area in face recognition. Future studies are needed to further explore the role of the more recently discovered anterior face-selective areas in face recognition. PMID:25714434

  1. Inverted Channels

    NASA Technical Reports Server (NTRS)

    2006-01-01

    23 June 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sinuous ridges and other landforms exposed by erosion in the Aeolis region of Mars. The ridges in this scene indicate the locations of ancient channels in a fan of sediment deposited in this region. Over time, wind erosion has removed surrounding materials and left the channels, which had been filled by sediment, standing as ridges.

    Location near: 4.5oS, 205.2oW Image width: 2 km (1.2 mi) Illumination from: upper left Season: Southern Autumn

  2. Simulation of mixing and ignition of hydrogen in channels at supersonic speeds

    NASA Astrophysics Data System (ADS)

    Vankova, O. S.; Valger, S. A.; Goldfeld, M. A.; Zakharova, Yu. V.; Fedorova, N. N.

    2016-10-01

    The paper presents the results of mathematical modeling of mixing and ignition of hydrogen jets in supersonic flow. Calculations were carried out on the basis of the Favre-averaged Navier-Stokes equations supplemented with k - ω SST turbulence model and detailed chemical kinetics. The solution was carried out in three stages. At the first stage, the kinetic schemes were tested by comparison with the experimental data on ignition of the hydrogen round jet supplied co axially with the M=2 air jet into the still air. The second 2D task was to study the process of mixing and ignition of hydrogen jets fed at various angles into the M=3 air flow at the channel with a cavity. At the third stage, the 3D problem of hydrogen jets supplied normally to a primary M=4 flow in the channel with backward-facing steps was computed under the condition of the experiments made at the hot-shot facility.

  3. Quartz Channel Fabrication for Electrokinetically Driven Separations

    SciTech Connect

    Arnold, D.W.; Ashby, C.I.H.; Bailey, C.G.; Kravitz, S.H., Warren, M.E.; Matzke, C.M.

    1998-12-01

    For well resolved electrokinetic separation, we L tilize crystalline quartz to micromachine a uniformly packe Q&iKLmnel. Packing features are posts 5 Vm on a side with:} pm spacing and etched 42 Vm deep. In addition to anisotropic wet etch characteristics for micromachining, quartz propmties are compatible with chemical soiutioits, ekctrokinetic high voltage operation, and stationary phase film depositions. To seal these channels, we employ a room temperature silicon-oxynhride deposition to forma membrane, that is subsequently coated for mechanical stability. Using this technique, particulate issues and global warp, that make large area wafer bon ding methods difficult, are avoided, and a room temperature process, in contrast to high temperature bonding techniques, accommodate preprocessing of metal films for electrical interconnect. After sealing channels, a number of macro-assembly steps are required to attach a micro-optical detection system and fluid interconnects. Keywords: microcharmel, integrated channel, micromachined channel, packed channel, electrokinetic channel, eleetrophoretic channel

  4. Starburst Channels

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies.

    In this example (figure 1) the channels form a 'starburst' pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out.

    Observation Geometry Image PSP_003443_0980 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 21-Apr-2007. The complete image is centered at -81.8 degrees latitude, 76.2 degrees East longitude. The range to the target site was 247.1 km (154.4 miles). At this distance the image scale is 24.7 cm/pixel (with 1 x 1 binning) so objects 74 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel. The image was taken at a local Mars time of 04:52 PM and the scene is illuminated from the west with a solar incidence angle of 71 degrees, thus the sun was about 19 degrees above the horizon. At a solar longitude of 223.4 degrees, the season on Mars is Northern Autumn.

  5. Starburst Channels

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies.

    In this example (figure 1) the channels form a 'starburst' pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out.

    Observation Geometry Image PSP_003443_0980 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 21-Apr-2007. The complete image is centered at -81.8 degrees latitude, 76.2 degrees East longitude. The range to the target site was 247.1 km (154.4 miles). At this distance the image scale is 24.7 cm/pixel (with 1 x 1 binning) so objects 74 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel. The image was taken at a local Mars time of 04:52 PM and the scene is illuminated from the west with a solar incidence angle of 71 degrees, thus the sun was about 19 degrees above the horizon. At a solar longitude of 223.4 degrees, the season on Mars is Northern Autumn.

  6. How Well Do Computer-Generated Faces Tap Face Expertise?

    PubMed Central

    Crookes, Kate; Ewing, Louise; Gildenhuys, Ju-dith; Kloth, Nadine; Hayward, William G.; Oxner, Matt; Pond, Stephen; Rhodes, Gillian

    2015-01-01

    The use of computer-generated (CG) stimuli in face processing research is proliferating due to the ease with which faces can be generated, standardised and manipulated. However there has been surprisingly little research into whether CG faces are processed in the same way as photographs of real faces. The present study assessed how well CG faces tap face identity expertise by investigating whether two indicators of face expertise are reduced for CG faces when compared to face photographs. These indicators were accuracy for identification of own-race faces and the other-race effect (ORE)–the well-established finding that own-race faces are recognised more accurately than other-race faces. In Experiment 1 Caucasian and Asian participants completed a recognition memory task for own- and other-race real and CG faces. Overall accuracy for own-race faces was dramatically reduced for CG compared to real faces and the ORE was significantly and substantially attenuated for CG faces. Experiment 2 investigated perceptual discrimination for own- and other-race real and CG faces with Caucasian and Asian participants. Here again, accuracy for own-race faces was significantly reduced for CG compared to real faces. However the ORE was not affected by format. Together these results signal that CG faces of the type tested here do not fully tap face expertise. Technological advancement may, in the future, produce CG faces that are equivalent to real photographs. Until then caution is advised when interpreting results obtained using CG faces. PMID:26535910

  7. Power module assemblies with staggered coolant channels

    DOEpatents

    Herron, Nicholas Hayden; Mann, Brooks S; Korich, Mark D

    2013-07-16

    A manifold is provided for supporting a power module assembly with a plurality of power modules. The manifold includes a first manifold section. The first face of the first manifold section is configured to receive the first power module, and the second face of the first manifold section defines a first cavity with a first baseplate thermally coupled to the first power module. The first face of the second manifold section is configured to receive the second power module, and the second face of the second manifold section defines a second cavity with a second baseplate thermally coupled to the second power module. The second face of the first manifold section and the second face of the second manifold section are coupled together such that the first cavity and the second cavity form a coolant channel. The first cavity is at least partially staggered with respect to second cavity.

  8. Detonation Diffraction in a Multi-Step Channel

    DTIC Science & Technology

    2010-12-01

    B. RANKINE HUGONIOT GAS DYANAMIC RELATIONS ...................... 5 C. ZEL’DOVICH–VON NEUMANN–DORING ( ZND ) ONE DIMENSIONAL WAVE STRUCTURE...the detonation. Some basic detonation models include Chapman–Jouguet and the ZND models. Main differences are depicted in Table 1. Table 1...11 Figure 7. Chapman–Jouguet tangency solutions (From [7]) C. ZEL’DOVICH–VON NEUMANN–DORING ( ZND ) ONE DIMENSIONAL WAVE STRUCTURE A simple

  9. Golgi-Cox Staining Step by Step

    PubMed Central

    Zaqout, Sami; Kaindl, Angela M.

    2016-01-01

    Golgi staining remains a key method to study neuronal morphology in vivo. Since most protocols delineating modifications of the original staining method lack details on critical steps, establishing this method in a laboratory can be time-consuming and frustrating. Here, we describe the Golgi-Cox staining in such detail that should turn the staining into an easily feasible method for all scientists working in the neuroscience field. PMID:27065817

  10. Clocking in the face of unpredictability beyond quantum uncertainty

    NASA Astrophysics Data System (ADS)

    Madjid, F. Hadi; Myers, John M.

    2015-05-01

    In earlier papers we showed unpredictability beyond quantum uncertainty in atomic clocks, ensuing from a proven gap between given evidence and explanations of that evidence. Here we reconceive a clock, not as an isolated entity, but as enmeshed in a self-adjusting communications network adapted to one or another particular investigation, in contact with an unpredictable environment. From the practical uses of clocks, we abstract a clock enlivened with the computational capacity of a Turing machine, modified to transmit and to receive numerical communications. Such "live clocks" phase the steps of their computations to mesh with the arrival of transmitted numbers. We lift this phasing, known in digital communications, to a principle of logical synchronization, distinct from the synchronization defined by Einstein in special relativity. Logical synchronization elevates digital communication to a topic in physics, including applications to biology. One explores how feedback loops in clocking affect numerical signaling among entities functioning in the face of unpredictable influences, making the influences themselves into subjects of investigation. The formulation of communications networks in terms of live clocks extends information theory by expressing the need to actively maintain communications channels, and potentially, to create or drop them. We show how networks of live clocks are presupposed by the concept of coordinates in a spacetime. A network serves as an organizing principle, even when the concept of the rigid body that anchors a special-relativistic coordinate system is inapplicable, as is the case, for example, in a generic curved spacetime.

  11. First Impressions From Faces.

    PubMed

    Zebrowitz, Leslie A

    2017-06-01

    Although cultural wisdom warns 'don't judge a book by its cover,' we seem unable to inhibit this tendency even though it can produce inaccurate impressions of people's psychological traits and has significant social consequences. One explanation for this paradox is that first impressions of faces overgeneralize our adaptive impressions of categories of people that those faces resemble (including babies, familiar or unfamiliar people, unfit people, emotional people). Research testing these 'overgeneralization' hypotheses elucidates why we form first impressions from faces, what impressions we form, and what cues influence these impressions. This article focuses on commonalities in impressions across diverse perceivers. However, brief attention is given to individual differences in impressions and impression accuracy.

  12. Facing Aggression: Cues Differ for Female versus Male Faces

    PubMed Central

    Geniole, Shawn N.; Keyes, Amanda E.; Mondloch, Catherine J.; Carré, Justin M.; McCormick, Cheryl M.

    2012-01-01

    The facial width-to-height ratio (face ratio), is a sexually dimorphic metric associated with actual aggression in men and with observers' judgements of aggression in male faces. Here, we sought to determine if observers' judgements of aggression were associated with the face ratio in female faces. In three studies, participants rated photographs of female and male faces on aggression, femininity, masculinity, attractiveness, and nurturing. In Studies 1 and 2, for female and male faces, judgements of aggression were associated with the face ratio even when other cues in the face related to masculinity were controlled statistically. Nevertheless, correlations between the face ratio and judgements of aggression were smaller for female than for male faces (F1,36 = 7.43, p = 0.01). In Study 1, there was no significant relationship between judgements of femininity and of aggression in female faces. In Study 2, the association between judgements of masculinity and aggression was weaker in female faces than for male faces in Study 1. The weaker association in female faces may be because aggression and masculinity are stereotypically male traits. Thus, in Study 3, observers rated faces on nurturing (a stereotypically female trait) and on femininity. Judgements of nurturing were associated with femininity (positively) and masculinity (negatively) ratings in both female and male faces. In summary, the perception of aggression differs in female versus male faces. The sex difference was not simply because aggression is a gendered construct; the relationships between masculinity/femininity and nurturing were similar for male and female faces even though nurturing is also a gendered construct. Masculinity and femininity ratings are not associated with aggression ratings nor with the face ratio for female faces. In contrast, all four variables are highly inter-correlated in male faces, likely because these cues in male faces serve as “honest signals”. PMID:22276184

  13. An equine pain face

    PubMed Central

    Gleerup, Karina B; Forkman, Björn; Lindegaard, Casper; Andersen, Pia H

    2015-01-01

    Objective The objective of this study was to investigate the existence of an equine pain face and to describe this in detail. Study design Semi-randomized, controlled, crossover trial. Animals Six adult horses. Methods Pain was induced with two noxious stimuli, a tourniquet on the antebrachium and topical application of capsaicin. All horses participated in two control trials and received both noxious stimuli twice, once with and once without an observer present. During all sessions their pain state was scored. The horses were filmed and the close-up video recordings of the faces were analysed for alterations in behaviour and facial expressions. Still images from the trials were evaluated for the presence of each of the specific pain face features identified from the video analysis. Results Both noxious challenges were effective in producing a pain response resulting in significantly increased pain scores. Alterations in facial expressions were observed in all horses during all noxious stimulations. The number of pain face features present on the still images from the noxious challenges were significantly higher than for the control trial (p = 0.0001). Facial expressions representative for control and pain trials were condensed into explanatory illustrations. During pain sessions with an observer present, the horses increased their contact-seeking behavior. Conclusions and clinical relevance An equine pain face comprising ‘low’ and/or ‘asymmetrical’ ears, an angled appearance of the eyes, a withdrawn and/or tense stare, mediolaterally dilated nostrils and tension of the lips, chin and certain facial muscles can be recognized in horses during induced acute pain. This description of an equine pain face may be useful for improving tools for pain recognition in horses with mild to moderate pain. PMID:25082060

  14. [Modern face lift surgery].

    PubMed

    von Gregory, H F; Gubisch, W

    2011-09-01

    Face lift surgery is generally considered the classical surgical procedure of plastic surgery. This is an extensive operation which has undergone a huge development since its first implementation more than 100 years ago. What began as a simple skin tightening procedure is today a sophisticated and complex technique which ideally combines different treatment methods planned with surgical precision. This article provides an overview of the history of the procedure to the present state of the art concept of pairing biplanar and bivectorial face-neck lifts with autologous fat transfer and dermabrasion.

  15. Information on stepping motors

    NASA Astrophysics Data System (ADS)

    Fongarland, G.

    1982-04-01

    The principles of the stepping motors which are often used in servomechanisms are reviewed. Variable reluctance as well as permanent magnet stepping motors are considered. Their operation is explained which includes permanent rotation, starting, stopping, and resonance effects. Several application examples, drawn from problems in automation, are outlined.

  16. Dynamic Channel Allocation

    DTIC Science & Technology

    2003-09-01

    7 1 . Fixed Channel Allocation (FCA) ........................................................7 2. Dynamic Channel ...19 7. CSMA/CD-Based Multiple Network Lines .....................................20 8. Hybrid Channel Allocation in Wireless Networks...28 1 . Channel Allocation

  17. Bayesian Face Recognition and Perceptual Narrowing in Face-Space

    ERIC Educational Resources Information Center

    Balas, Benjamin

    2012-01-01

    During the first year of life, infants' face recognition abilities are subject to "perceptual narrowing", the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in…

  18. Voicing on Virtual and Face to Face Discussion

    ERIC Educational Resources Information Center

    Yamat, Hamidah

    2013-01-01

    This paper presents and discusses findings of a study conducted on pre-service teachers' experiences in virtual and face to face discussions. Technology has brought learning nowadays beyond the classroom context or time zone. The learning context and process no longer rely solely on face to face communications in the presence of a teacher.…

  19. Bayesian Face Recognition and Perceptual Narrowing in Face-Space

    ERIC Educational Resources Information Center

    Balas, Benjamin

    2012-01-01

    During the first year of life, infants' face recognition abilities are subject to "perceptual narrowing", the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in…

  20. Conjunction Faces Alter Confidence-Accuracy Relations for Old Faces

    ERIC Educational Resources Information Center

    Reinitz, Mark Tippens; Loftus, Geoffrey R.

    2017-01-01

    The authors used a state-trace methodology to investigate the informational dimensions used to recognize old and conjunction faces (made by combining parts of separately studied faces). Participants in 3 experiments saw faces presented for 1 s each. They then received a recognition test; faces were presented for varying brief durations and…

  1. STEP Experiment Requirements

    NASA Technical Reports Server (NTRS)

    Brumfield, M. L. (Compiler)

    1984-01-01

    A plan to develop a space technology experiments platform (STEP) was examined. NASA Langley Research Center held a STEP Experiment Requirements Workshop on June 29 and 30 and July 1, 1983, at which experiment proposers were invited to present more detailed information on their experiment concept and requirements. A feasibility and preliminary definition study was conducted and the preliminary definition of STEP capabilities and experiment concepts and expected requirements for support services are presented. The preliminary definition of STEP capabilities based on detailed review of potential experiment requirements is investigated. Topics discussed include: Shuttle on-orbit dynamics; effects of the space environment on damping materials; erectable beam experiment; technology for development of very large solar array deployers; thermal energy management process experiment; photovoltaic concentrater pointing dynamics and plasma interactions; vibration isolation technology; flight tests of a synthetic aperture radar antenna with use of STEP.

  2. Faceness-Net: Face Detection through Deep Facial Part Responses.

    PubMed

    Yang, Shuo; Luo, Ping; Loy, Chen Change; Tang, Xiaoou

    2017-08-11

    We propose a deep convolutional neural network (CNN) for face detection leveraging on facial attributes based supervision. We observe a phenomenon that part detectors emerge within CNN trained to classify attributes from uncropped face images, without any explicit part supervision. The observation motivates a new method for finding faces through scoring facial parts responses by their spatial structure and arrangement. The scoring mechanism is data-driven, and carefully formulated considering challenging cases where faces are only partially visible. This consideration allows our network to detect faces under severe occlusion and unconstrained pose variations. Our method achieves promising performance on popular benchmarks including FDDB, PASCAL Faces, AFW, and WIDER FACE.

  3. Face recognition system and method using face pattern words and face pattern bytes

    DOEpatents

    Zheng, Yufeng

    2014-12-23

    The present invention provides a novel system and method for identifying individuals and for face recognition utilizing facial features for face identification. The system and method of the invention comprise creating facial features or face patterns called face pattern words and face pattern bytes for face identification. The invention also provides for pattern recognitions for identification other than face recognition. The invention further provides a means for identifying individuals based on visible and/or thermal images of those individuals by utilizing computer software implemented by instructions on a computer or computer system and a computer readable medium containing instructions on a computer system for face recognition and identification.

  4. Facing Up to Death

    ERIC Educational Resources Information Center

    Ross, Elizabeth Kubler

    1972-01-01

    Doctor urges that Americans accept death as a part of life and suggests ways of helping dying patients and their families face reality calmly, with peace. Dying children and their siblings, as well as children's feelings about relatives' deaths, are also discussed. (PD)

  5. Lightweight Face Mask

    NASA Technical Reports Server (NTRS)

    Cason, W. E. I.; Baucom, R. M.; Evans, R. C.

    1982-01-01

    Lightweight face mask originally developed to protect epileptic patients during seizures could have many other medical and nonmedical applications such as muscular distrophy patients, football linesmen and riot-control police. Masks are extremely lightweight, the lightest of the configurations weighing only 136 grams.

  6. Facing the Not Knowing

    ERIC Educational Resources Information Center

    Tennant, Roy

    2007-01-01

    In this article, the author talks about how to face the not knowing and offers a strategy to fill the gap of not knowing. In coping with constant change, he describes a strategy for library staff that might help in the absence of certainty. This includes: (a) guarding the data with one's life; (b) build not for longevity, but obsolescence; (c)…

  7. Two Faces of Japan.

    ERIC Educational Resources Information Center

    Beasley, Conger, Jr.

    1992-01-01

    Discusses the inconsistency between Japanese exploitation of world natural resources and gestures to provide leadership in ecologically innovative technology. Explores Japanese culture, power structure, population trends, environmental ethics, industrialism, and international business practices as they relate to the philosophical face of…

  8. Facing Up to Death

    ERIC Educational Resources Information Center

    Ross, Elizabeth Kubler

    1972-01-01

    Doctor urges that Americans accept death as a part of life and suggests ways of helping dying patients and their families face reality calmly, with peace. Dying children and their siblings, as well as children's feelings about relatives' deaths, are also discussed. (PD)

  9. Anatomy of ageing face.

    PubMed

    Ilankovan, V

    2014-03-01

    Ageing is a biological process that results from changes at a cellular level, particularly modification of mRNA. The face is affected by the same physiological process and results in skeletal, muscular, and cutaneous ageing; ligamentous attenuation, descent of fat, and ageing of the appendages. I describe these changes on a structural and clinical basis and summarise possible solutions for a rejuvenation surgeon.

  10. Facing the Not Knowing

    ERIC Educational Resources Information Center

    Tennant, Roy

    2007-01-01

    In this article, the author talks about how to face the not knowing and offers a strategy to fill the gap of not knowing. In coping with constant change, he describes a strategy for library staff that might help in the absence of certainty. This includes: (a) guarding the data with one's life; (b) build not for longevity, but obsolescence; (c)…

  11. Lightweight Face Mask

    NASA Technical Reports Server (NTRS)

    Cason, W. E. I.; Baucom, R. M.; Evans, R. C.

    1982-01-01

    Lightweight face mask originally developed to protect epileptic patients during seizures could have many other medical and nonmedical applications such as muscular distrophy patients, football linesmen and riot-control police. Masks are extremely lightweight, the lightest of the configurations weighing only 136 grams.

  12. Challenges Facing Special Education.

    ERIC Educational Resources Information Center

    Meyen, Edward L., Ed.; And Others

    This book presents 17 selected papers from recent issues of the journal, "Focus on Exceptional Children," concerning current and emerging challenges facing the field of special education. The book is organized in two parts. Part 1, "Contemporary Challenges," includes the following articles: "Transitions in Early Childhood Special Education: Issues…

  13. Automated Face Recognition System

    DTIC Science & Technology

    1992-12-01

    done at the University of California San Diego will be given(3, 1). Finally, the review will end with a short overview of the Karhunen Lorve and...define a face space. This basis set which is optimally tuned to the training data is derived using the Karhunen Lorve principal component analysis (7

  14. Two Faces of Japan.

    ERIC Educational Resources Information Center

    Beasley, Conger, Jr.

    1992-01-01

    Discusses the inconsistency between Japanese exploitation of world natural resources and gestures to provide leadership in ecologically innovative technology. Explores Japanese culture, power structure, population trends, environmental ethics, industrialism, and international business practices as they relate to the philosophical face of…

  15. Bayesian Face Sketch Synthesis.

    PubMed

    Wang, Nannan; Gao, Xinbo; Sun, Leiyu; Li, Jie

    2017-03-01

    Exemplar-based face sketch synthesis has been widely applied to both digital entertainment and law enforcement. In this paper, we propose a Bayesian framework for face sketch synthesis, which provides a systematic interpretation for understanding the common properties and intrinsic difference in different methods from the perspective of probabilistic graphical models. The proposed Bayesian framework consists of two parts: the neighbor selection model and the weight computation model. Within the proposed framework, we further propose a Bayesian face sketch synthesis method. The essential rationale behind the proposed Bayesian method is that we take the spatial neighboring constraint between adjacent image patches into consideration for both aforementioned models, while the state-of-the-art methods neglect the constraint either in the neighbor selection model or in the weight computation model. Extensive experiments on the Chinese University of Hong Kong face sketch database demonstrate that the proposed Bayesian method could achieve superior performance compared with the state-of-the-art methods in terms of both subjective perceptions and objective evaluations.

  16. Challenges Facing Special Education.

    ERIC Educational Resources Information Center

    Meyen, Edward L., Ed.; And Others

    This book presents 17 selected papers from recent issues of the journal, "Focus on Exceptional Children," concerning current and emerging challenges facing the field of special education. The book is organized in two parts. Part 1, "Contemporary Challenges," includes the following articles: "Transitions in Early Childhood Special Education: Issues…

  17. Workforce Issues Facing HRD.

    ERIC Educational Resources Information Center

    1995

    These four papers are from a symposium facilitated by Eugene Andette on work force issues facing human resources development (HRD) at the 1995 Academy of Human Resource Development conference. "Meaning Construction and Personal Transformation: Alternative Dimensions of Job Loss" (Terri A. Deems) reports a study conducted to explore the ways…

  18. Problems Facing Rural Schools.

    ERIC Educational Resources Information Center

    Stewart, C. E.; And Others

    Problems facing rural Scottish schools range from short term consideration of daily operation to long term consideration of organizational alternatives. Addressed specifically, such problems include consideration of: (1) liaison between a secondary school and its feeder primary schools; (2) preservice teacher training for work in small, isolated…

  19. The Caledonian face test: A new test of face discrimination.

    PubMed

    Logan, Andrew J; Wilkinson, Frances; Wilson, Hugh R; Gordon, Gael E; Loffler, Gunter

    2016-02-01

    This study aimed to develop a clinical test of face perception which is applicable to a wide range of patients and can capture normal variability. The Caledonian face test utilises synthetic faces which combine simplicity with sufficient realism to permit individual identification. Face discrimination thresholds (i.e. minimum difference between faces required for accurate discrimination) were determined in an "odd-one-out" task. The difference between faces was controlled by an adaptive QUEST procedure. A broad range of face discrimination sensitivity was determined from a group (N=52) of young adults (mean 5.75%; SD 1.18; range 3.33-8.84%). The test is fast (3-4 min), repeatable (test-re-test r(2)=0.795) and demonstrates a significant inversion effect. The potential to identify impairments of face discrimination was evaluated by testing LM who reported a lifelong difficulty with face perception. While LM's impairment for two established face tests was close to the criterion for significance (Z-scores of -2.20 and -2.27) for the Caledonian face test, her Z-score was -7.26, implying a more than threefold higher sensitivity. The new face test provides a quantifiable and repeatable assessment of face discrimination ability. The enhanced sensitivity suggests that the Caledonian face test may be capable of detecting more subtle impairments of face perception than available tests.

  20. 1. Northeast face of missile site control building, commonly known ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Northeast face of missile site control building, commonly known as the missile site radar building, showing open blast door #BD2. This emergency escape, at stair no. 12, is NEMP/RFI-shielded and 16" thick. The large circle in the center is the radar face, also known as the antennae array aperture. The small circle to the right of the radar face is the "Q" channel. The antennae atop the turret provided lightning protection for the building - Stanley R. Mickelsen Safeguard Complex, Missile Site Control Building, Northeast of Tactical Road; southeast of Tactical Road South, Nekoma, Cavalier County, ND

  1. Molecular aspects of human brain sodium channel.

    PubMed

    De Rycker, C; Schoffeniels, E

    1990-01-01

    The sodium channel content of human brain was measured by tritiated tetrodotoxin specific binding. After solubilization, the sodium channel was submitted to chromatography on diethylaminoethyl(cellulose) Sephadex, hydroxylapatite and wheat germ agglutinin sepharose. An increase of tritiated tetrodotoxin binding specific activity was subsequently observed. Eluted sodium channels from wheat germ agglutinin sepharose were overlaid on a sucrose gradient. Electrophoretical analysis of the material obtained after the sedimentation step revealed two co-purified peptides, alpha (Mr = 275,000 mol. wt) and beta (Mr = 30,000-36,000 mol. wt.). Alpha showed an exceptionally high free electrophoretic mobility, which is a common feature for all sodium channels previously described. However, the high denaturation rate of the solubilized tetrodotoxin receptor site 1 did not allow tetrodotoxin receptor quantification by the tritiated toxin binding in sucrose fractions. Sodium channel effective reconstitution in liposomes was demonstrated: (1) 22Na+ influx in proteoliposomes was sensitive to sodium channel-specific neurotoxins: (2) reconstituted proteins showed a cation selectivity similar to that previously described for animal sodium channels. The sodium channel preparation obtained after four chromatographic steps shows two peptides on the electrophoretic analysis. Reconstituted sodium channels displayed some physiological properties found in intact conducting membranes.

  2. Finding Faces Among Faces: Human Faces are Located More Quickly and Accurately than Other Primate and Mammal Faces

    PubMed Central

    Simpson, Elizabeth A.; Buchin, Zachary; Werner, Katie; Worrell, Rey; Jakobsen, Krisztina V.

    2014-01-01

    We tested the specificity of human face search efficiency by examining whether there is a broad window of detection for various face-like stimuli—human and animal faces—or whether own-species faces receive greater attentional allocation. We assessed the strength of the own-species face detection bias by testing whether human faces are located more efficiently than other animal faces, when presented among various other species’ faces, in heterogeneous 16-, 36-, and 64-item arrays. Across all array sizes, we found that, controlling for distractor type, human faces were located faster and more accurately than primate and mammal faces, and that, controlling for target type, searches were faster when distractors were human faces compared to animal faces, revealing more efficient processing of human faces regardless of their role as targets or distractors (Experiment 1). Critically, these effects remained when searches were for specific species’ faces (human, chimpanzee, otter), ruling out a category-level explanation (Experiment 2). Together, these results suggest that human faces may be processed more efficiently than animal faces, both when task-relevant (targets), and when task-irrelevant (distractors), even when in direct competition with other faces. These results suggest that there is not a broad window of detection for all face-like patterns, but that human adults process own-species’ faces more efficiently than other species’ faces. Such own-species search efficiencies may arise through experience with own-species faces throughout development, or may be privileged early in development, due to the evolutionary importance of conspecifics’ faces. PMID:25113852

  3. View down into vertical flame channel of Test Stand 'A' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View down into vertical flame channel of Test Stand 'A' from superstructure. Wooden platform open side faces west. - Jet Propulsion Laboratory Edwards Facility, Test Stand A, Edwards Air Force Base, Boron, Kern County, CA

  4. 8. VIEW OF DAM 83, SHOWING OLD SOURIS RIVER CHANNEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF DAM 83, SHOWING OLD SOURIS RIVER CHANNEL FROM THE DOWNSTREAM FACE OF THE DAM WITH POND A IN THE BACKGROUND, LOOKING SOUTH - Upper Souris National Wildlife Refuge, Dam 83, Souris River Basin, Foxholm, Surrey (England), ND

  5. Human faces are slower than chimpanzee faces.

    PubMed

    Burrows, Anne M; Parr, Lisa A; Durham, Emily L; Matthews, Lea C; Smith, Timothy D

    2014-01-01

    While humans (like other primates) communicate with facial expressions, the evolution of speech added a new function to the facial muscles (facial expression muscles). The evolution of speech required the development of a coordinated action between visual (movement of the lips) and auditory signals in a rhythmic fashion to produce "visemes" (visual movements of the lips that correspond to specific sounds). Visemes depend upon facial muscles to regulate shape of the lips, which themselves act as speech articulators. This movement necessitates a more controlled, sustained muscle contraction than that produced during spontaneous facial expressions which occur rapidly and last only a short period of time. Recently, it was found that human tongue musculature contains a higher proportion of slow-twitch myosin fibers than in rhesus macaques, which is related to the slower, more controlled movements of the human tongue in the production of speech. Are there similar unique, evolutionary physiologic biases found in human facial musculature related to the evolution of speech? Using myosin immunohistochemistry, we tested the hypothesis that human facial musculature has a higher percentage of slow-twitch myosin fibers relative to chimpanzees (Pan troglodytes) and rhesus macaques (Macaca mulatta). We sampled the orbicularis oris and zygomaticus major muscles from three cadavers of each species and compared proportions of fiber-types. Results confirmed our hypothesis: humans had the highest proportion of slow-twitch myosin fibers while chimpanzees had the highest proportion of fast-twitch fibers. These findings demonstrate that the human face is slower than that of rhesus macaques and our closest living relative, the chimpanzee. They also support the assertion that human facial musculature and speech co-evolved. Further, these results suggest a unique set of evolutionary selective pressures on human facial musculature to slow down while the function of this muscle group diverged

  6. The own-age face recognition bias is task dependent.

    PubMed

    Proietti, Valentina; Macchi Cassia, Viola; Mondloch, Catherine J

    2015-08-01

    The own-age bias (OAB) in face recognition (more accurate recognition of own-age than other-age faces) is robust among young adults but not older adults. We investigated the OAB under two different task conditions. In Experiment 1 young and older adults (who reported more recent experience with own than other-age faces) completed a match-to-sample task with young and older adult faces; only young adults showed an OAB. In Experiment 2 young and older adults completed an identity detection task in which we manipulated the identity strength of target and distracter identities by morphing each face with an average face in 20% steps. Accuracy increased with identity strength and facial age influenced older adults' (but not younger adults') strategy, but there was no evidence of an OAB. Collectively, these results suggest that the OAB depends on task demands and may be absent when searching for one identity. © 2014 The British Psychological Society.

  7. Tritium Removal from Carbon Plasma Facing Components

    SciTech Connect

    C.H. Skinner; J.P. Coad; G. Federici

    2003-11-24

    Tritium removal is a major unsolved development task for next-step devices with carbon plasma-facing components. The 2-3 order of magnitude increase in duty cycle and associated tritium accumulation rate in a next-step tokamak will place unprecedented demands on tritium removal technology. The associated technical risk can be mitigated only if suitable removal techniques are demonstrated on tokamaks before the construction of a next-step device. This article reviews the history of codeposition, the tritium experience of TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) and the tritium removal rate required to support ITER's planned operational schedule. The merits and shortcomings of various tritium removal techniques are discussed with particular emphasis on oxidation and laser surface heating.

  8. The Next Giant Step

    NASA Image and Video Library

    Artist Robert McCall painted "The Next Giant Step" in 1979 to commemorate the heroism and courage of spaceflight pioneers. Located in the lobby of Johnson's building 2, the mural depicts America's ...

  9. The California "Step System."

    ERIC Educational Resources Information Center

    Manaster, Alfred

    1985-01-01

    The University of California's "step" system for appointment and advancement of faculty and the salary scale attached to it are outlined, and some criteria and procedures used in making academic personnel decisions are reviewed. (MSE)

  10. Middle School STEP Act

    THOMAS, 113th Congress

    Sen. Kaine, Tim [D-VA

    2014-09-10

    Senate - 09/10/2014 Read twice and referred to the Committee on Health, Education, Labor, and Pensions. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

  11. CEIP Next Steps

    EPA Pesticide Factsheets

    The Clean Energy Incentive Program (CEIP) next steps document details the EPA’s outreach strategy for stakeholder input on the design and implementation of the CEIP. Additionally, this document lists provisions on the CEIP where stakeholder input is sought

  12. Face-n-Food: Gender Differences in Tuning to Faces.

    PubMed

    Pavlova, Marina A; Scheffler, Klaus; Sokolov, Alexander N

    2015-01-01

    Faces represent valuable signals for social cognition and non-verbal communication. A wealth of research indicates that women tend to excel in recognition of facial expressions. However, it remains unclear whether females are better tuned to faces. We presented healthy adult females and males with a set of newly created food-plate images resembling faces (slightly bordering on the Giuseppe Arcimboldo style). In a spontaneous recognition task, participants were shown a set of images in a predetermined order from the least to most resembling a face. Females not only more readily recognized the images as a face (they reported resembling a face on images, on which males still did not), but gave on overall more face responses. The findings are discussed in the light of gender differences in deficient face perception. As most neuropsychiatric, neurodevelopmental and psychosomatic disorders characterized by social brain abnormalities are sex specific, the task may serve as a valuable tool for uncovering impairments in visual face processing.

  13. Viscoelasticity of stepped interfaces

    NASA Astrophysics Data System (ADS)

    Skirlo, S. A.; Demkowicz, M. J.

    2013-10-01

    Using molecular dynamics modeling, we show that interfaces in sputter deposited Cu-Nb superlattices exhibit time-dependent elasticity, i.e., viscoelasticity, under shear loading. In the high temperature and small strain rate limit, the interfacial shear modulus approaches a value proportional to the density of steps in the interface. It may therefore be possible to tailor the low-frequency shear moduli of interfaces by controlling their step densities.

  14. 'Happy Face' Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-361, 15 May 2003

    Every day, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle instruments obtain a global view of the planet to help monitor weather and seasonal patterns of frost deposition and removal. The two pictures shown here are taken from the same daily global image mosaic (the only difference is that each was processed slightly differently). The pictures show Galle Crater, informally known as 'Happy Face,' as it appeared in early southern winter. The white-ish gray surfaces are coated with wintertime carbon dioxide frost. The pattern of frost distribution gives the appearance that 'Happy Face' has opened its mouth. Galle Crater is located on the east rim of Argyre at 51oS, 31oW. Sunlight illuminates the scene from the upper left. Galle Crater is 230 km (143 mi) across.

  15. Producing desired ice faces

    PubMed Central

    Shultz, Mary Jane; Brumberg, Alexandra; Bisson, Patrick J.; Shultz, Ryan

    2015-01-01

    The ability to prepare single-crystal faces has become central to developing and testing models for chemistry at interfaces, spectacularly demonstrated by heterogeneous catalysis and nanoscience. This ability has been hampered for hexagonal ice, Ih––a fundamental hydrogen-bonded surface––due to two characteristics of ice: ice does not readily cleave along a crystal lattice plane and properties of ice grown on a substrate can differ significantly from those of neat ice. This work describes laboratory-based methods both to determine the Ih crystal lattice orientation relative to a surface and to use that orientation to prepare any desired face. The work builds on previous results attaining nearly 100% yield of high-quality, single-crystal boules. With these methods, researchers can prepare authentic, single-crystal ice surfaces for numerous studies including uptake measurements, surface reactivity, and catalytic activity of this ubiquitous, fundamental solid. PMID:26512102

  16. CRYSTAL/FACE

    NASA Technical Reports Server (NTRS)

    Baumgardner, Darrel; Kok, Greg; Anderson, Bruce

    2004-01-01

    Droplet Measurement Technologies (DMT), under funding from NASA, participated in the CRYSTAL/FACE field campaign in July, 2002 with measurements of cirrus cloud hydrometeors in the size range from 0.5 to 1600 microns. The measurements were made with the DMT Cloud, Aerosol and Precipitation Spectrometer (CAPS) that was flown on NASA's WB57F. With the exception of the first research flight when the data system failed two hours into the mission, the measurement system performed almost flawlessly during the thirteen flights. The measurements from the CAPS have been essential for interpretation of cirrus cloud properties and their impact on climate. The CAPS data set has been used extensively by the CRYSTAL/FACE investigators and as of the date of this report, have been included in five published research articles, 10 conference presentations and six other journal articles currently in preparation.

  17. CRYSTAL/FACE

    NASA Technical Reports Server (NTRS)

    Baumgardner, Darrel; Kok, Greg; Anderson, Bruce

    2004-01-01

    Droplet Measurement Technologies (DMT), under funding from NASA, participated in the CRYSTAL/FACE field campaign in July, 2002 with measurements of cirrus cloud hydrometeors in the size range from 0.5 to 1600 microns. The measurements were made with the DMT Cloud, Aerosol and Precipitation Spectrometer (CAPS) that was flown on NASA's WB57F. With the exception of the first research flight when the data system failed two hours into the mission, the measurement system performed almost flawlessly during the thirteen flights. The measurements from the CAPS have been essential for interpretation of cirrus cloud properties and their impact on climate. The CAPS data set has been used extensively by the CRYSTAL/FACE investigators and as of the date of this report, have been included in five published research articles, 10 conference presentations and six other journal articles currently in preparation.

  18. Current—voltage curve of sodium channels and concentration dependence of sodium permeability in frog skin

    PubMed Central

    Fuchs, W.; Larsen, E. Hviid; Lindemann, B.

    1977-01-01

    1. The inward facing membranes of in vitro frog skin epithelium were depolarized with solutions of high K concentration. The electrical properties of the epithelium are then expected to be governed by the outward facing, Na-selective membrane. 2. In this state, the transepithelial voltage (V) was clamped to zero and step-changes of Na activity in the outer solution ((Na)o) were performed with a fast-flow chamber at constant ionic strength, while the short-circuit current was recorded. 3. At pre-selected times after a step-change of (Na)o the current response (I) to a fast voltage staircase was recorded. This procedure was repeated after blocking the Na channels with amiloride to obtain the current—voltage curve of transmembrane and paracellular shunt pathways. The current—voltage curve of the Na channels was computed by subtracting the shunt current from the total current. 4. The instantaneous INa—V curve thus obtained at a given (Na)o could easily be fitted with the constant field equation in the range between -50 and zero mV. This fit yielded approximate estimates of PNa, the Na— permeability of the Na-selective membrane (at this (Na)o) and the cellular Na activity, (Na)c. As residual properties of the serosal membrane were ignored the computed values are expected to underestimate the true ones. 5. At constant (Na)c, the steady-state value of 1/PNa increases linearly with (Na)o. Error analysis and the effect of drugs show that the dependence is not due to the residual properties of the inward facing membranes but reflects the true behaviour of PNa. 6. The steady-state PNa at a given (Na)o is smaller than the transient PNa observed right after a stepwise increase of (Na)o to this value. The time constant of PNa-relaxation is in the order of seconds. 7. In conclusion, Na transport through open Na-selective channels of the outward facing membrane of the stratum granulosum cells can be described as an electrodiffusion process which as such does not saturate

  19. On the other side of the mean: the perception of dissimilarity in human faces.

    PubMed

    Blanz, V; O'Toole, A J; Vetter, T; Wild, H A

    2000-01-01

    We created a 'face space' using a laser-scan representation of faces. In this space, a caricature can be made by moving a face away from the average face, along the line connecting the particular face to the average face. Here, we move the face along this line in the other direction, proceeding through the mean and 'out the other side'. This results in a face that is 'opposite', in a computational sense, to the original face. We morphed several faces into their anti-faces and sampled the morph trajectory in five discrete steps. We then collected similarity ratings from human participants for all possible pairs of morphed faces to determine how the distances in the 'physical face space' related to the distances in the 'psychological face space'. The data indicate that there is a perceptual discontinuity of face identity as the face crosses over to the 'other side of the mean'. We consider these results in the context of face-space models of human face processing.

  20. 19. View of dedication plaque on the north tower facing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. View of dedication plaque on the north tower facing south. The view is oblique because that portion of the approach trestles immediately in front of the plaque was removed in 1979. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  1. Northern Hemisphere Gullies on West-Facing Crater Slope, Mars

    NASA Image and Video Library

    2010-06-09

    This image from NASA Mars Reconnaissance Orbiter shows the west-facing side of an impact crater in the mid-latitudes of Mars northern hemisphere. This crater has gullies along its walls that are composed of alcoves, channels and debris aprons.

  2. 49. Machinery rooms on north tower. Facing north. Machinery rooms ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. Machinery rooms on north tower. Facing north. Machinery rooms contain all motors, motor controllers, and gears for operating one span, in this case, the north span. Note bell with continuous operating clapper for use as fog signals. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  3. 23. View of Clark Fork Vehicle Bridge facing upwest side. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. View of Clark Fork Vehicle Bridge facing up-west side. Looking at structural connection of top chord, vertical laced channel and diagonal bars. - Clark Fork Vehicle Bridge, Spanning Clark Fork River, serves Highway 200, Clark Fork, Bonner County, ID

  4. 35. Ca. 1930 historic view facing northeast, showing Yellow Mill ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. Ca. 1930 historic view facing northeast, showing Yellow Mill Bridge and inset showing former ca. 1901 Yellow Mill Bridge. Photo located at the Bridgeport Public Library, Bridgeport, CT. - Yellow Mill Bridge, Spanning Yellow Mill Channel at Stratford Avenue, Bridgeport, Fairfield County, CT

  5. Synthesis and characterization of "face-to-face" porphyrins.

    PubMed Central

    Collman, J P; Elliott, C M; Halbert, T R; Tovrog, B S

    1977-01-01

    The syntheses of four binary porphyrins, two of which are constrained to a "face-to-face" conformation, and their Co2+ and Cu2+ derivatives are described. Electron spin resonance indicates that the intermetallic separation in the binuclear "face-to-face" porphyrins is about 6.5-6.8 A. Electronic spectra and proton magnetic resonance spectra support the postulated "face-to-face" conformations. A hypothesis that related compounds may serve as multielectron redox catalysts for O2 and N2 is presented. PMID:189304

  6. Foil Face Seal Testing

    NASA Technical Reports Server (NTRS)

    Munson, John

    2009-01-01

    In the seal literature you can find many attempts by various researchers to adapt film riding seals to the gas turbine engine. None have been successful, potential distortion of the sealing faces is the primary reason. There is a film riding device that does accommodate distortion and is in service in aircraft applications, namely the foil bearing. More specifically a foil thrust bearing. These are not intended to be seals, and they do not accommodate large axial movement between shaft & static structure. By combining the 2 a unique type of face seal has been created. It functions like a normal face seal. The foil thrust bearing replaces the normal primary sealing surface. The compliance of the foil bearing allows the foils to track distortion of the mating seal ring. The foil seal has several perceived advantages over existing hydrodynamic designs, enumerated in the chart. Materials and design methodology needed for this application already exist. Also the load capacity requirements for the foil bearing are low since it only needs to support itself and overcome friction forces at the antirotation keys.

  7. Double face sealing device

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce (Inventor)

    1991-01-01

    A double face sealing device is disclosed for mounting between two surfaces to provide an air-tight and fluid-tight seal between a closure member bearing one of the surfaces and a structure or housing bearing the other surface which extends around the opening or hatchway to be closed. The double face sealing device includes a plurality of sections or segments mounted to one of the surfaces, each having a main body portion, a pair of outwardly extending and diverging, cantilever, spring arms, and a pair of inwardly extending and diverging, cantilever, spring arms, an elastomeric cover on the distal, free ends of the outwardly extending and diverging spring arms, and an elastomeric cover on the distal, free, ends of the outwardly extending and diverging spring arms, and an elastomeric cover on the distal, free ends of the inwardly extending and diverging spring arms. The double face sealing device has application or use in all environments requiring a seal, but is particularly useful to seal openings or hatchways between compartments of spacecraft or aircraft.

  8. Simulating newborn face perception.

    PubMed

    von Hofsten, Olov; von Hofsten, Claes; Sulutvedt, Unni; Laeng, Bruno; Brennen, Tim; Magnussen, Svein

    2014-11-18

    A frequently asked question concerns what a newborn infant can actually see. The contrast sensitivity function of newborn infants is well known, but its implications for the ability of newborns to perceive faces of adults remain unclear. We filtered gray scale animations of facial expressions in terms of both spatial frequency and contrast to correspond to the properties of newborn infants' acuity and showed them to adult participants. We reasoned that if adults were unable to identify the depicted facial expressions, then it would also seem unlikely that newborn infants could identify the same expressions. We found that for the simulated acuity the different expressions could be rather well identified at a distance of 30 cm, but when the distance was increased to 120 cm their discriminability was much degraded. This shows that although the perception of faces and facial expressions can function at the low visual resolution of the newborn infant, it is insufficient for distinguishing faces and facial expressions at moderate distances. © 2014 ARVO.

  9. Beyond Faces and Expertise

    PubMed Central

    Zhao, Mintao; Bülthoff, Heinrich H.; Bülthoff, Isabelle

    2016-01-01

    Holistic processing—the tendency to perceive objects as indecomposable wholes—has long been viewed as a process specific to faces or objects of expertise. Although current theories differ in what causes holistic processing, they share a fundamental constraint for its generalization: Nonface objects cannot elicit facelike holistic processing in the absence of expertise. Contrary to this prevailing view, here we show that line patterns with salient Gestalt information (i.e., connectedness, closure, and continuity between parts) can be processed as holistically as faces without any training. Moreover, weakening the saliency of Gestalt information in these patterns reduced holistic processing of them, which indicates that Gestalt information plays a crucial role in holistic processing. Therefore, holistic processing can be achieved not only via a top-down route based on expertise, but also via a bottom-up route relying merely on object-based information. The finding that facelike holistic processing can extend beyond the domains of faces and objects of expertise poses a challenge to current dominant theories. PMID:26674129

  10. Ionic Channels as Natural Nanodevices

    DTIC Science & Technology

    2006-05-01

    introduce the numerical techniques required to simulate charge transport in ion channels. [1] Using Poisson - Nernst - Planck -type (PNP) equations...Using a force-field scheme based on a Poisson particle-particle-particle-mesh algorithm, they made, “an initial step toward the development of an...7.0 - Bibliography Aboud, S., Marreiro, D., Saraniti, M., and R. Eisenberg. 2004. A Poisson P3M Force Field Scheme for Particle-Based Simulations

  11. Face antispoofing based on frame difference and multilevel representation

    NASA Astrophysics Data System (ADS)

    Benlamoudi, Azeddine; Aiadi, Kamal Eddine; Ouafi, Abdelkrim; Samai, Djamel; Oussalah, Mourad

    2017-07-01

    Due to advances in technology, today's biometric systems become vulnerable to spoof attacks made by fake faces. These attacks occur when an intruder attempts to fool an established face-based recognition system by presenting a fake face (e.g., print photo or replay attacks) in front of the camera instead of the intruder's genuine face. For this purpose, face antispoofing has become a hot topic in face analysis literature, where several applications with antispoofing task have emerged recently. We propose a solution for distinguishing between real faces and fake ones. Our approach is based on extracting features from the difference between successive frames instead of individual frames. We also used a multilevel representation that divides the frame difference into multiple multiblocks. Different texture descriptors (local binary patterns, local phase quantization, and binarized statistical image features) have then been applied to each block. After the feature extraction step, a Fisher score is applied to sort the features in ascending order according to the associated weights. Finally, a support vector machine is used to differentiate between real and fake faces. We tested our approach on three publicly available databases: CASIA Face Antispoofing database, Replay-Attack database, and MSU Mobile Face Spoofing database. The proposed approach outperforms the other state-of-the-art methods in different media and quality metrics.

  12. Face-space: A unifying concept in face recognition research.

    PubMed

    Valentine, Tim; Lewis, Michael B; Hills, Peter J

    2016-10-01

    The concept of a multidimensional psychological space, in which faces can be represented according to their perceived properties, is fundamental to the modern theorist in face processing. Yet the idea was not clearly expressed until 1991. The background that led to the development of face-space is explained, and its continuing influence on theories of face processing is discussed. Research that has explored the properties of the face-space and sought to understand caricature, including facial adaptation paradigms, is reviewed. Face-space as a theoretical framework for understanding the effect of ethnicity and the development of face recognition is evaluated. Finally, two applications of face-space in the forensic setting are discussed. From initially being presented as a model to explain distinctiveness, inversion, and the effect of ethnicity, face-space has become a central pillar in many aspects of face processing. It is currently being developed to help us understand adaptation effects with faces. While being in principle a simple concept, face-space has shaped, and continues to shape, our understanding of face perception.

  13. Effectiveness randomized controlled trial of face to face versus Internet cognitive behaviour therapy for social phobia.

    PubMed

    Andrews, Gavin; Davies, Matthew; Titov, Nickolai

    2011-04-01

    To compare the effectiveness of Internet cognitive behaviour therapy (CBT) with face-to-face CBT in social phobia. Randomized controlled trial of 75 patients with social phobia referred to an anxiety disorders clinic. A total of 37 patients participated, and post-treatment data was obtained from 25 Subjects (Ss). An intention to treat analysis was used. The same therapist (M.D.) treated both groups. Both groups made significant progress on symptoms and disability measures. There were no significant differences in outcome between the Internet and face-to-face groups. The total amount of therapist time required was 18 min per patient for the Internet group and 240 min per patient for the face-to-face group. Both forms of treatment were equally effective and this is consistent with previous findings in depression and panic disorder. The difference in clinician time required was substantial. If Internet CBT was offered as 'standard of care' the staff time saved would permit a stepped care model in which in-depth therapy for the difficult to recover patients could be provided without an increase in staff.

  14. Age-Dependent Face Detection and Face Categorization Performance

    PubMed Central

    Carbon, Claus-Christian; Grüter, Martina; Grüter, Thomas

    2013-01-01

    Empirical studies on the development of face processing skills with age show inconsistent patterns concerning qualitative vs. quantitative changes over time or the age range for peak cognitive performance. In the present study, we tested the proficiency in face detection and face categorization with a large sample of participants (N = 312; age range: 2-88 yrs). As test objects, we used so-called Mooney faces, two-tone (black and white) images of faces lacking critical information of a local, featural and relational nature, reflecting difficult real world face processing conditions. We found that performance in the assessment of gender and age from Mooney faces increases up to about age 15, and decreases from 65 years on. The implications of these findings are discussed in the light of classic and recent findings from face development literature. PMID:24116236

  15. 9. WEST FACE OF OLD THEODOLITE BUILDING; WEST FACE OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. WEST FACE OF OLD THEODOLITE BUILDING; WEST FACE OF EAST PHOTO TOWER IN BACKGROUND - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  16. A new "fat face" illusion.

    PubMed

    Sun, Yu-Hao; Ge, Liezhong; Quinn, Paul C; Wang, Zhe; Xiao, Naiqi G; Pascalis, Olivier; Tanaka, James; Lee, Kang

    2012-01-01

    We report a novel fat face illusion that when two identical images of the same face are aligned vertically, the face at the bottom appears 'fatter'. This illusion emerged when the faces were shown upright, but not inverted, with the size of the illusion being 4%. When the faces were presented upside down, the illusion did not emerge. Also, when upright clocks were shown in the same vertically aligned fashion, we did not observe the illusion, indicating that the fat illusion does not generalize to every category of canonically upright objects with similar geometric shape as a face.

  17. Kruskal-Wallis-Based Computationally Efficient Feature Selection for Face Recognition

    PubMed Central

    Hussain, Ayyaz; Basit, Abdul

    2014-01-01

    Face recognition in today's technological world, and face recognition applications attain much more importance. Most of the existing work used frontal face images to classify face image. However these techniques fail when applied on real world face images. The proposed technique effectively extracts the prominent facial features. Most of the features are redundant and do not contribute to representing face. In order to eliminate those redundant features, computationally efficient algorithm is used to select the more discriminative face features. Extracted features are then passed to classification step. In the classification step, different classifiers are ensemble to enhance the recognition accuracy rate as single classifier is unable to achieve the high accuracy. Experiments are performed on standard face database images and results are compared with existing techniques. PMID:24967437

  18. The molecular physiology of CRAC channels

    PubMed Central

    Prakriya, Murali

    2011-01-01

    Summary The Ca2+release-activated Ca2+ (CRAC) channel is a highly Ca2+-selective store-operated channel expressed in T cells, mast cells, and various other tissues. CRAC channels regulate critical cellular processes such as gene expression, motility, and the secretion of inflammatory mediators. The identification of Orai1, a key subunit of the CRAC channel pore, and STIM1, the endoplasmic reticulum (ER) Ca2+ sensor, have provided the tools to illuminate the mechanisms of regulation and the pore properties of CRAC channels. Recent evidence indicates that the activation of CRAC channels by store depletion involves a coordinated series of steps, which include the redistributions of STIM1 and Orai1, direct physical interactions between these proteins, and conformational changes in Orai1, culminating in channel activation. Additional studies have revealed that the high Ca2+ selectivity of CRAC channels arises from the presence of an intrapore Ca2+ binding site, the properties of which are finely honed to occlude the permeation of the much more prevalent Na+. Structure-function studies have led to the identification of the potential pore-binding sites for Ca2+, providing a firm framework for understanding the mechanisms of selectivity and gating of the CRAC channel. This review summarizes recent progress in understanding the mechanisms of CRAC channel activation, pore properties, and modulation. PMID:19754891

  19. Eukaryotic mechanosensitive channels.

    PubMed

    Arnadóttir, Jóhanna; Chalfie, Martin

    2010-01-01

    Mechanosensitive ion channels are gated directly by physical stimuli and transduce these stimuli into electrical signals. Several criteria must apply for a channel to be considered mechanically gated. Mechanosensitive channels from bacterial systems have met these criteria, but few eukaryotic channels have been confirmed by the same standards. Recent work has suggested or confirmed that diverse types of channels, including TRP channels, K(2P) channels, MscS-like proteins, and DEG/ENaC channels, are mechanically gated. Several studies point to the importance of the plasma membrane for channel gating, but intracellular and/or extracellular structures may also be required.

  20. 6. VIEW OF DAM 83, SHOWING OUTLET CHANNEL FLOWING INTO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. VIEW OF DAM 83, SHOWING OUTLET CHANNEL FLOWING INTO POND A WITH DIVERSION GATES LONG EAST (LEFT) SIDE OF OUTLET CHANNEL, LOOKING SOUTH FROM DOWNSTREAM FACE OF THE DAM - Upper Souris National Wildlife Refuge, Dam 83, Souris River Basin, Foxholm, Surrey (England), ND

  1. LOOKING DOWNSTREAM FROM KACHESS DAM CREST, 1910 RIVER CUTOFF CHANNEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LOOKING DOWNSTREAM FROM KACHESS DAM CREST, 1910 RIVER CUTOFF CHANNEL WITH CRIB STRUCTURE IN CENTER. BRIDGE FOOTING CRIB STRUCTURE AT RIGHT (Upstream face of Kachess Dam in foreground) - Kachess Dam, Cutoff Channel and Crib Structures, Kachess River, 1.5 miles north of Interstate 90, Easton, Kittitas County, WA

  2. The Internet and the Banks' Strategic Distribution Channel Decisions.

    ERIC Educational Resources Information Center

    Mols, Niels Peter

    1998-01-01

    Discusses two strategic distribution channel decisions facing banks, one regarding whether to target the Internet banking segment of customers versus the branch banking segment, and the other regarding the geographical area banks aim to serve. Future distribution channels, the change process, and local, national, and international strategies are…

  3. The Internet and the Banks' Strategic Distribution Channel Decisions.

    ERIC Educational Resources Information Center

    Mols, Niels Peter

    1998-01-01

    Discusses two strategic distribution channel decisions facing banks, one regarding whether to target the Internet banking segment of customers versus the branch banking segment, and the other regarding the geographical area banks aim to serve. Future distribution channels, the change process, and local, national, and international strategies are…

  4. Facing rim cavities fluctuation modes

    NASA Astrophysics Data System (ADS)

    Casalino, Damiano; Ribeiro, André F. P.; Fares, Ehab

    2014-06-01

    Cavity modes taking place in the rims of two opposite wheels are investigated through Lattice-Boltzmann CFD simulations. Based on previous observations carried out by the authors during the BANC-II/LAGOON landing gear aeroacoustic study, a resonance mode can take place in the volume between the wheels of a two-wheel landing gear, involving a coupling between shear-layer vortical fluctuations and acoustic modes resulting from the combination of round cavity modes and wheel-to-wheel transversal acoustic modes. As a result, side force fluctuations and tonal noise side radiation take place. A parametric study of the cavity mode properties is carried out in the present work by varying the distance between the wheels. Moreover, the effects due to the presence of the axle are investigated by removing the axle from the two-wheel assembly. The azimuthal properties of the modes are scrutinized by filtering the unsteady flow in narrow bands around the tonal frequencies and investigating the azimuthal structure of the filtered fluctuation modes. Estimation of the tone frequencies with an ad hoc proposed analytical formula confirms the observed modal properties of the filtered unsteady flow solutions. The present study constitutes a primary step in the description of facing rim cavity modes as a possible source of landing gear tonal noise.

  5. Bayesian face recognition and perceptual narrowing in face-space.

    PubMed

    Balas, Benjamin

    2012-07-01

    During the first year of life, infants' face recognition abilities are subject to 'perceptual narrowing', the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in developing humans and primates. Though the phenomenon is highly robust and replicable, there have been few efforts to model the emergence of perceptual narrowing as a function of the accumulation of experience with faces during infancy. The goal of the current study is to examine how perceptual narrowing might manifest as statistical estimation in 'face-space', a geometric framework for describing face recognition that has been successfully applied to adult face perception. Here, I use a computer vision algorithm for Bayesian face recognition to study how the acquisition of experience in face-space and the presence of race categories affect performance for own and other-race faces. Perceptual narrowing follows from the establishment of distinct race categories, suggesting that the acquisition of category boundaries for race is a key computational mechanism in developing face expertise. © 2012 Blackwell Publishing Ltd.

  6. Face-to-Face Interference in Typical and Atypical Development

    ERIC Educational Resources Information Center

    Riby, Deborah M.; Doherty-Sneddon, Gwyneth; Whittle, Lisa

    2012-01-01

    Visual communication cues facilitate interpersonal communication. It is important that we look at faces to retrieve and subsequently process such cues. It is also important that we sometimes look away from faces as they increase cognitive load that may interfere with online processing. Indeed, when typically developing individuals hold face gaze…

  7. Bayesian Face Recognition and Perceptual Narrowing in Face-Space

    PubMed Central

    Balas, Benjamin

    2012-01-01

    During the first year of life, infants’ face recognition abilities are subject to “perceptual narrowing,” the end result of which is that observers lose the ability to distinguish previously discriminable faces (e.g. other-race faces) from one another. Perceptual narrowing has been reported for faces of different species and different races, in developing humans and primates. Though the phenomenon is highly robust and replicable, there have been few efforts to model the emergence of perceptual narrowing as a function of the accumulation of experience with faces during infancy. The goal of the current study is to examine how perceptual narrowing might manifest as statistical estimation in “face space,” a geometric framework for describing face recognition that has been successfully applied to adult face perception. Here, I use a computer vision algorithm for Bayesian face recognition to study how the acquisition of experience in face space and the presence of race categories affect performance for own and other-race faces. Perceptual narrowing follows from the establishment of distinct race categories, suggesting that the acquisition of category boundaries for race is a key computational mechanism in developing face expertise. PMID:22709406

  8. The 'Face' of Jupiter

    NASA Image and Video Library

    2017-06-29

    JunoCam images aren't just for art and science -- sometimes they are processed to bring a chuckle. This image, processed by citizen scientist Jason Major, is titled "Jovey McJupiterface." By rotating the image 180 degrees and orienting it from south up, two white oval storms turn into eyeballs, and the "face" of Jupiter is revealed. The original image was acquired by JunoCam on NASA's Juno spacecraft on May 19, 2017 at 11:20 a.m. PT (2: 20 p.m. ET) from an altitude of 12,075 miles (19,433 kilometers). https://photojournal.jpl.nasa.gov/catalog/PIA21394

  9. Challenges facing production grids

    SciTech Connect

    Pordes, Ruth; /Fermilab

    2007-06-01

    Today's global communities of users expect quality of service from distributed Grid systems equivalent to that their local data centers. This must be coupled to ubiquitous access to the ensemble of processing and storage resources across multiple Grid infrastructures. We are still facing significant challenges in meeting these expectations, especially in the underlying security, a sustainable and successful economic model, and smoothing the boundaries between administrative and technical domains. Using the Open Science Grid as an example, I examine the status and challenges of Grids operating in production today.

  10. Mucormycosis of the face.

    PubMed

    Piazza, Rocco C; Thomas, Wendy L; Stawski, Willard S; Ford, Ronald D

    2009-01-01

    As burn wound sepsis continues to be one of the most common causes of death in burn patients, it is important to note the trend of increased involvement of fungal pathogens. Very little exists in the literature regarding management of such fungal infections. We report invasive cutaneous mucormycosis involving the face of an extensively burned patient with no prior medical history that would otherwise predispose her to such infection. Diagnosis and management are discussed leading to eventual eradication of the Mucor and survival of our patient.

  11. Coronal Hole Faces Earth

    NASA Image and Video Library

    2017-08-14

    A substantial coronal hole rotated into a position where it is facing Earth (Aug. 9-11, 2017). Coronal holes are areas of open magnetic field that spew out charged particles as solar wind that spreads into space. If that solar wind interacts with our own magnetosphere it can generate aurora. In this view of the sun in extreme ultraviolet light, the coronal hole appears as the dark stretch near the center of the sun. It was the most distinctive feature on the sun over the past week. Movies are available at https://photojournal.jpl.nasa.gov/catalog/PIA21874

  12. Face the Fats Quiz 2

    MedlinePlus

    Face the Fats Quiz II Do you know your fats by heart? Ready to make informed choices about the foods you ... to fried chicken, test your knowledge about the fats in some familiar foods. Welcome to Face the ...

  13. Aging changes in the face

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/004004.htm Aging changes in the face To use the sharing ... face with age References Brodie SE, Francis JH. Aging and disorders of the eye. In: Fillit HM, ...

  14. Vitiligo on the face (image)

    MedlinePlus

    This is a picture of vitiligo on the face. Complete loss of melanin, the primary skin pigment, ... the same areas on both sides of the face -- symmetrically -- or it may be patchy -- asymmetrical. The ...

  15. Cellobiohydrolase Hydrolyzes Crystalline Cellulose on Hydrophobic Faces*

    PubMed Central

    Liu, Yu-San; Baker, John O.; Zeng, Yining; Himmel, Michael E.; Haas, Thomas; Ding, Shi-You

    2011-01-01

    Biodegradation of plant biomass is a slow process in nature, and hydrolysis of cellulose is also widely considered to be a rate-limiting step in the proposed industrial process of converting lignocellulosic materials to biofuels. It is generally known that a team of enzymes including endo- and exocellulases as well as cellobiases are required to act synergistically to hydrolyze cellulose to glucose. The detailed molecular mechanisms of these enzymes have yet to be convincingly elucidated. In this report, atomic force microscopy (AFM) is used to image in real-time the structural changes in Valonia cellulose crystals acted upon by the exocellulase cellobiohydrolase I (CBH I) from Trichoderma reesei. Under AFM, single enzyme molecules could be observed binding only to one face of the cellulose crystal, apparently the hydrophobic face. The surface roughness of cellulose began increasing after adding CBH I, and the overall size of cellulose crystals decreased during an 11-h period. Interestingly, this size reduction apparently occurred only in the width of the crystal, whereas the height remained relatively constant. In addition, the measured cross-section shape of cellulose crystal changed from asymmetric to nearly symmetric. These observed changes brought about by CBH I action may constitute the first direct visualization supporting the idea that the exocellulase selectively hydrolyzes the hydrophobic faces of cellulose. The limited accessibility of the hydrophobic faces in native cellulose may contribute significantly to the rate-limiting slowness of cellulose hydrolysis. PMID:21282110

  16. A hybrid approach for face template protection

    NASA Astrophysics Data System (ADS)

    Feng, Y. C.; Yuen, Pong C.; Jain, Anil K.

    2008-03-01

    Biometric template protection is one of the important issues in deploying a practical biometric system. To tackle this problem, many algorithms have been reported in recent years, most of them being applicable to fingerprint biometric. Since the content and representation of fingerprint template is different from templates of other modalities such as face, the fingerprint template protection algorithms cannot be directly applied to face template. Moreover, we believe that no single template protection method is capable of satisfying the diversity, revocability, security and performance requirements. We propose a three-step cancelable framework which is a hybrid approach for face template protection. This hybrid algorithm is based on the random projection, class distribution preserving transform and hash function. Two publicly available face databases, namely FERET and CMU-PIE, are used for evaluating the template protection scheme. Experimental results show that the proposed method maintains good template discriminability, resulting in good recognition performance. A comparison with the recently developed random multispace quantization (RMQ) biohashing algorithm shows that our method outperforms the RMQ algorithm.

  17. Boulder-Faced Log Dams and other Alternatives for Gabion Check Dams in First-Order Ephemeral Streams with Coarse Bed Load in Ethiopia

    NASA Astrophysics Data System (ADS)

    Nyssen, Jan; Gebreslassie, Seifu; Assefa, Romha; Deckers, Jozef; Guyassa, Etefa; Poesen, Jean; Frankl, Amaury

    2017-04-01

    Many thousands of gabion check dams have been installed to control gully erosion in Ethiopia, but several challenges still remain, such as the issue of gabion failure in ephemeral streams with coarse bed load, that abrades at the chute step. As an alternative for gabion check dams in torrents with coarse bed load, boulder-faced log dams were conceived, installed transversally across torrents and tested (n = 30). For this, logs (22-35 cm across) were embedded in the banks of torrents, 0.5-1 m above the bed and their upstream sides were faced with boulders (0.3-0.7 m across). Similar to gabion check dams, boulder-faced log dams lead to temporary ponding, spreading of peak flow over the entire channel width and sediment deposition. Results of testing under extreme flow conditions (including two storms with return periods of 5.6 and 7 years) show that 18 dams resisted strong floods. Beyond certain flood thresholds, represented by proxies such as Strahler's stream order, catchment area, D95 or channel width), 11 log dams were completely destroyed. Smallholder farmers see much potential in this type of structure to control first-order torrents with coarse bed load, since the technique is cost-effective and can be easily installed.

  18. IntraFace

    PubMed Central

    De la Torre, Fernando; Chu, Wen-Sheng; Xiong, Xuehan; Vicente, Francisco; Ding, Xiaoyu; Cohn, Jeffrey

    2016-01-01

    Within the last 20 years, there has been an increasing interest in the computer vision community in automated facial image analysis algorithms. This has been driven by applications in animation, market research, autonomous-driving, surveillance, and facial editing among others. To date, there exist several commercial packages for specific facial image analysis tasks such as facial expression recognition, facial attribute analysis or face tracking. However, free and easy-to-use software that incorporates all these functionalities is unavailable. This paper presents IntraFace (IF), a publicly-available software package for automated facial feature tracking, head pose estimation, facial attribute recognition, and facial expression analysis from video. In addition, IFincludes a newly develop technique for unsupervised synchrony detection to discover correlated facial behavior between two or more persons, a relatively unexplored problem in facial image analysis. In tests, IF achieved state-of-the-art results for emotion expression and action unit detection in three databases, FERA, CK+ and RU-FACS; measured audience reaction to a talk given by one of the authors; and discovered synchrony for smiling in videos of parent-infant interaction. IF is free of charge for academic use at http://www.humansensing.cs.cmu.edu/intraface/. PMID:27346987

  19. Detecting Faces in Impoverished Images

    DTIC Science & Technology

    2001-11-01

    International Conference on Face and Gesture Recognition , Nara, Japan. Heisle, B., T. Serre, S. Mukherjee and T. Poggio. (2001) Feature Reduction and...Third International Conference on Face and Gesture Recognition , Nara, Japan. Leung, T. K., Burl, M. C., & Perona, P. (1995). Finding faces in...of invariant moments. Proceedings of the Third International Conference on Face and Gesture Recognition , Nara, Japan. Thornhill, R. and Gangestad

  20. The Seven Step Strategy

    ERIC Educational Resources Information Center

    Schaffer, Connie

    2017-01-01

    Many well-intended instructors use Socratic or leveled questioning to facilitate the discussion of an assigned reading. While this engages a few students, most can opt to remain silent. The seven step strategy described in this article provides an alternative to classroom silence and engages all students. Students discuss a single reading as they…

  1. The effect of contrast polarity reversal on face detection: evidence of perceptual asymmetry from sweep VEP.

    PubMed

    Liu-Shuang, Joan; Ales, Justin M; Rossion, Bruno; Norcia, Anthony M

    2015-03-01

    Contrast polarity inversion (i.e., turning dark regions light and vice versa) impairs face perception. We investigated the perceptual asymmetry between positive and negative polarity faces (matched for overall luminance) using a sweep VEP approach in the context of face detection (Journal of Vision 12 (2012) 1-18). Phase-scrambled face stimuli alternated at a rate of 3 Hz (6 images/s). The phase coherence of every other stimulus was parametrically increased so that a face gradually emerged over a 20-s stimulation sequence, leading to a 3 Hz response reflecting face detection. Contrary to the 6 Hz response, reflecting low-level visual processing, this 3 Hz response was larger and emerged earlier over right occipito-temporal channels for positive than negative polarity faces. Moreover, the 3 Hz response emerged abruptly to positive polarity faces, whereas it increased linearly for negative polarity faces. In another condition, alternating between a positive and a negative polarity face also elicited a strong 3 Hz response, indicating an asymmetrical representation of positive and negative polarity faces even at supra-threshold levels (i.e., when both stimuli were perceived as faces). Overall, these findings demonstrate distinct perceptual representations of positive and negative polarity faces, independently of low-level cues, and suggest qualitatively different detection processes (template-based matching for positive polarity faces vs. linear accumulation of evidence for negative polarity faces).

  2. A novel thermal face recognition approach using face pattern words

    NASA Astrophysics Data System (ADS)

    Zheng, Yufeng

    2010-04-01

    A reliable thermal face recognition system can enhance the national security applications such as prevention against terrorism, surveillance, monitoring and tracking, especially at nighttime. The system can be applied at airports, customs or high-alert facilities (e.g., nuclear power plant) for 24 hours a day. In this paper, we propose a novel face recognition approach utilizing thermal (long wave infrared) face images that can automatically identify a subject at both daytime and nighttime. With a properly acquired thermal image (as a query image) in monitoring zone, the following processes will be employed: normalization and denoising, face detection, face alignment, face masking, Gabor wavelet transform, face pattern words (FPWs) creation, face identification by similarity measure (Hamming distance). If eyeglasses are present on a subject's face, an eyeglasses mask will be automatically extracted from the querying face image, and then masked with all comparing FPWs (no more transforms). A high identification rate (97.44% with Top-1 match) has been achieved upon our preliminary face dataset (of 39 subjects) from the proposed approach regardless operating time and glasses-wearing condition.e

  3. FaceID: A face detection and recognition system

    SciTech Connect

    Shah, M.B.; Rao, N.S.V.; Olman, V.; Uberbacher, E.C.; Mann, R.C.

    1996-12-31

    A face detection system that automatically locates faces in gray-level images is described. Also described is a system which matches a given face image with faces in a database. Face detection in an Image is performed by template matching using templates derived from a selected set of normalized faces. Instead of using original gray level images, vertical gradient images were calculated and used to make the system more robust against variations in lighting conditions and skin color. Faces of different sizes are detected by processing the image at several scales. Further, a coarse-to-fine strategy is used to speed up the processing, and a combination of whole face and face component templates are used to ensure low false detection rates. The input to the face recognition system is a normalized vertical gradient image of a face, which is compared against a database using a set of pretrained feedforward neural networks with a winner-take-all fuser. The training is performed by using an adaptation of the backpropagation algorithm. This system has been developed and tested using images from the FERET database and a set of images obtained from Rowley, et al and Sung and Poggio.

  4. Face gender modulates women's brain activity during face encoding.

    PubMed

    Lovén, Johanna; Svärd, Joakim; Ebner, Natalie C; Herlitz, Agneta; Fischer, Håkan

    2014-07-01

    Women typically remember more female than male faces, whereas men do not show a reliable own-gender bias. However, little is known about the neural correlates of this own-gender bias in face recognition memory. Using functional magnetic resonance imaging (fMRI), we investigated whether face gender modulated brain activity in fusiform and inferior occipital gyri during incidental encoding of faces. Fifteen women and 14 men underwent fMRI while passively viewing female and male faces, followed by a surprise face recognition task. Women recognized more female than male faces and showed higher activity to female than male faces in individually defined regions of fusiform and inferior occipital gyri. In contrast, men's recognition memory and blood-oxygen-level-dependent response were not modulated by face gender. Importantly, higher activity in the left fusiform gyrus (FFG) to one gender was related to better memory performance for that gender. These findings suggest that the FFG is involved in the gender bias in memory for faces, which may be linked to differential experience with female and male faces. © The Author (2013). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  5. Adaptive face coding and discrimination around the average face.

    PubMed

    Rhodes, Gillian; Maloney, Laurence T; Turner, Jenny; Ewing, Louise

    2007-03-01

    Adaptation paradigms highlight the dynamic nature of face coding and suggest that identity is coded relative to an average face that is tuned by experience. In low-level vision, adaptive coding can enhance sensitivity to differences around the adapted level. We investigated whether sensitivity to differences around the average face is similarly enhanced. Converging evidence from three paradigms showed no enhancement. Discrimination of small interocular spacing differences was not better for faces close to the average (Study 1). Nor was perceived similarity reduced for face pairs close to (spanning) the average (Study 2). On the contrary, these pairs were judged most similar. Maximum likelihood perceptual difference scaling (Studies 3 and 4) confirmed that sensitivity to differences was reduced, not enhanced, around the average. We conclude that adaptive face coding does not enhance discrimination around the average face.

  6. [The head nurse faced with nurses' rites of passages].

    PubMed

    Foulon, M

    2000-12-01

    The caregivers, faced with a death, have repetitive and meaningless attitudes. The concept of rite, developed by Pierre CAZE-NEUVE, reveals that a rite can be characterized by three elements: stereotyped, repetitive and meaningless. The passage rite is made up of three steps: separation, margin and aggregation. The passage rites are defence mechanisms installed by the caregivers to fight against an element which they do not master, the death of a patient. The role of the head nurse can come in three forms: a protection role in order to give caregivers good working conditions, an attention faced with the limits of the rite as well as a vigilance faced with negative rites.

  7. 3D Face Modeling Using the Multi-Deformable Method

    PubMed Central

    Hwang, Jinkyu; Yu, Sunjin; Kim, Joongrock; Lee, Sangyoun

    2012-01-01

    In this paper, we focus on the problem of the accuracy performance of 3D face modeling techniques using corresponding features in multiple views, which is quite sensitive to feature extraction errors. To solve the problem, we adopt a statistical model-based 3D face modeling approach in a mirror system consisting of two mirrors and a camera. The overall procedure of our 3D facial modeling method has two primary steps: 3D facial shape estimation using a multiple 3D face deformable model and texture mapping using seamless cloning that is a type of gradient-domain blending. To evaluate our method's performance, we generate 3D faces of 30 individuals and then carry out two tests: accuracy test and robustness test. Our method shows not only highly accurate 3D face shape results when compared with the ground truth, but also robustness to feature extraction errors. Moreover, 3D face rendering results intuitively show that our method is more robust to feature extraction errors than other 3D face modeling methods. An additional contribution of our method is that a wide range of face textures can be acquired by the mirror system. By using this texture map, we generate realistic 3D face for individuals at the end of the paper. PMID:23201976

  8. 3D Face modeling using the multi-deformable method.

    PubMed

    Hwang, Jinkyu; Yu, Sunjin; Kim, Joongrock; Lee, Sangyoun

    2012-09-25

    In this paper, we focus on the problem of the accuracy performance of 3D face modeling techniques using corresponding features in multiple views, which is quite sensitive to feature extraction errors. To solve the problem, we adopt a statistical model-based 3D face modeling approach in a mirror system consisting of two mirrors and a camera. The overall procedure of our 3D facial modeling method has two primary steps: 3D facial shape estimation using a multiple 3D face deformable model and texture mapping using seamless cloning that is a type of gradient-domain blending. To evaluate our method's performance, we generate 3D faces of 30 individuals and then carry out two tests: accuracy test and robustness test. Our method shows not only highly accurate 3D face shape results when compared with the ground truth, but also robustness to feature extraction errors. Moreover, 3D face rendering results intuitively show that our method is more robust to feature extraction errors than other 3D face modeling methods. An additional contribution of our method is that a wide range of face textures can be acquired by the mirror system. By using this texture map, we generate realistic 3D face for individuals at the end of the paper.

  9. Real-time iris detection on rotated faces

    NASA Astrophysics Data System (ADS)

    Perez, Claudio A.; Lazcano, Vanel A.; Estevez, Pablo A.; Held, Claudio M.

    2003-10-01

    Real-time face and iris detection on video sequences has been used to study the eye function and in diverse applications such as drowsiness detection, virtual keyboard interfaces, face recognition and multimedia retrieval. A non-invasive real time iris detection method was developed and consists of three stages: coarse face detection, fine face detection and iris detection. Anthropometric templates are used in these three stages. Elliptical templates are used to locate the coarse face center. A set of anthropometric templates which are probabilistic maps for the eyebrows, nose and mouth are used to perform the fine face detection. Face rotations are considered by rotating the anthropometric templates in fixed angles in steps of 10 degrees. Iris position is then determined within the eye region using another template with concentric semi-circles to compute a line integral in the boundary iris-sclera. The position with the maximum value indicates the iris center. The new method was applied on 10 video sequences, with a total of 6470 frames, from different people rotating their faces in the coronal axis. Results of correct face detection on 8 video sequences was 100%, one reached 99.9% and one 98.2%. Results on correct iris detection are above 96% in 9 of the video sequences and one reached 77.8%. The method was implemented in real-time (30 frames per second) with a PC 1.8 GHz.

  10. Two Faces of Pluto

    NASA Image and Video Library

    2015-07-01

    This pair of approximately true color images of Pluto and its big moon Charon, taken by NASA's New Horizons spacecraft, highlight the dramatically different appearance of different sides of the dwarf planet, and reveal never-before-seen details on Pluto's varied surface. The views were made by combining high-resolution black-and-white images from the Long Range Reconnaissance Imager (LORRI) with color information from the lower-resolution color camera that is part of the Ralph instrument. The left-hand image shows the side of Pluto that always faces away from Charon -- this is the side that will be seen at highest resolution by New Horizons when it makes its close approach to Pluto on July 14th. This hemisphere is dominated by a very dark region that extends along the equator and is redder than its surroundings, alongside a strikingly bright, paler-colored region which straddles the equator on the right-hand side of the disk. The opposite hemisphere, the side that faces Charon, is seen in the right-hand image. The most dramatic feature on this side of Pluto is a row of dark dots arranged along the equator. The origin of all these features is still mysterious, but may be revealed in the much more detailed images that will be obtained as the spacecraft continues its approach to Pluto. In both images, Charon shows a darker and grayer color than Pluto, and a conspicuous dark polar region. The left-hand image was obtained at 5:37 UT on June 25th 2015, at a distance from Pluto of 22.9 million kilometers (14.3 million miles) and has a central longitude of 152 degrees. The right-hand image was obtained at 23:15 UT on June 27th 2015, at a distance from Pluto of 19.7 million kilometers (12.2 million miles) with a central longitude of 358 degrees. Insets show the orientation of Pluto in each image -- the solid lines mark the equator and the prime meridian, which is defined to be the longitude that always faces Charon. The smallest visible features are about 200 km (120 miles

  11. Autocyclic Formation, Retreat, and Destruction of Waterfalls in an Experimental Bedrock Channel

    NASA Astrophysics Data System (ADS)

    Scheingross, J. S.; Fuller, B. M.; Lamb, M. P.

    2015-12-01

    Waterfalls are ubiquitous in steep landscapes and have been documented to retreat upstream at rates far outpacing standard fluvial incision into bedrock. While the formation of waterfalls following changes in climate and base-level lowering have been well-documented, little work has explored the formation of waterfalls via the internal dynamics from interacting flow hydraulics, sediment flux, and evolving channel morphology. Distinguishing between waterfalls formed via external versus internal forcing is important, as waterfall formation and retreat rate is often applied in inverse to determine the timing of external forcing. Here, we present results from a laboratory experiment designed to explore channel incision and waterfall formation. We fed water and sediment at constant rates over an initially planar surface at 19.5% slope. A channel rapidly incised into the artificial bedrock substrate, and small-wavelength variations in erosion rate created steps and pools which grew in amplitude. As pools deepened, erosion was focused on the upstream pool faces creating steep segments in the channel bed. At the topographic breaks between these steep segments and their upstream treads, water detached from the bed forming ventilated waterfall jets which impacted the plunge pools below. Continued pool deepening led to sediment deposition on the pool floors, locally inhibiting vertical incision while the upstream and downstream surfaces were free to erode. Amplified erosion at the waterfall lip incised a new pool into the bedrock previously composing the waterfall face while simultaneous lowering of the downstream pool lip resulted in the destruction of the original pool. Repetition of this process in our experiment suggests that interactions between bedrock erosion and sediment cover can result in the formation of a series of plunge pools which retreat upstream, and that care must be taken to distinguish between autocyclic versus allocyclic waterfall formation in studies

  12. Face Processing: Models For Recognition

    NASA Astrophysics Data System (ADS)

    Turk, Matthew A.; Pentland, Alexander P.

    1990-03-01

    The human ability to process faces is remarkable. We can identify perhaps thousands of faces learned throughout our lifetime and read facial expression to understand such subtle qualities as emotion. These skills are quite robust, despite sometimes large changes in the visual stimulus due to expression, aging, and distractions such as glasses or changes in hairstyle or facial hair. Computers which model and recognize faces will be useful in a variety of applications, including criminal identification, human-computer interface, and animation. We discuss models for representing faces and their applicability to the task of recognition, and present techniques for identifying faces and detecting eye blinks.

  13. Reanimating the paralyzed face

    PubMed Central

    2013-01-01

    Facial animation is an essential part of human communication and one of the main means of expressing emotions, indexing our physiologic state and providing nonverbal cues. The loss of this important human quality due to facial paralysis can be devastating and is often associated with depression, social isolation and poor quality of life. Interruption of the neuromuscular pathway from the facial motor cortex to the facial muscles is the common causative factor in facial paralysis resulting from various etiologies. Restoring tone, symmetry and movement to the paralyzed face requires timely nerve grafting intervention in cases of reversible paralysis and the transfer of functional muscle units in irreversible paralysis. We review recent advances in these techniques. PMID:24273650

  14. Fusion of active and passive infrared images for face recognition

    NASA Astrophysics Data System (ADS)

    Akhloufi, Moulay A.; Bendada, Abdelhakim

    2013-05-01

    This work introduces a new framework for active and passive infrared image fusion for face recognition applications. Two multispectral face recognition databases were used in our experiments: Equinox Database (Visible, SWIR, MWIR, LWIR) and m-Faces Database (Visible, NIR, MWIR, LWIR). The proposed framework uses a fusion scheme in texture space in order to increase the performance of face recognition. The proposed texture space is based on the use of binary and ternary patterns. A new adaptive ternary pattern is also introduced. Active (SWIR and NIR) and passive (MWIR, LWIR) infrared modalities are used in this fusion scheme. An intraspectral and inter-spectral fusion approaches are introduced. The obtained results are promising and show an increase in the recognition performance when texture channels are fused in a multi-scale fusion scheme.

  15. The many faces of research on face perception

    PubMed Central

    Little, Anthony C.; Jones, Benedict C.; DeBruine, Lisa M.

    2011-01-01

    Face perception is fundamental to human social interaction. Many different types of important information are visible in faces and the processes and mechanisms involved in extracting this information are complex and can be highly specialized. The importance of faces has long been recognized by a wide range of scientists. Importantly, the range of perspectives and techniques that this breadth has brought to face perception research has, in recent years, led to many important advances in our understanding of face processing. The articles in this issue on face perception each review a particular arena of interest in face perception, variously focusing on (i) the social aspects of face perception (attraction, recognition and emotion), (ii) the neural mechanisms underlying face perception (using brain scanning, patient data, direct stimulation of the brain, visual adaptation and single-cell recording), and (iii) comparative aspects of face perception (comparing adult human abilities with those of chimpanzees and children). Here, we introduce the central themes of the issue and present an overview of the articles. PMID:21536550

  16. The many faces of research on face perception.

    PubMed

    Little, Anthony C; Jones, Benedict C; DeBruine, Lisa M

    2011-06-12

    Face perception is fundamental to human social interaction. Many different types of important information are visible in faces and the processes and mechanisms involved in extracting this information are complex and can be highly specialized. The importance of faces has long been recognized by a wide range of scientists. Importantly, the range of perspectives and techniques that this breadth has brought to face perception research has, in recent years, led to many important advances in our understanding of face processing. The articles in this issue on face perception each review a particular arena of interest in face perception, variously focusing on (i) the social aspects of face perception (attraction, recognition and emotion), (ii) the neural mechanisms underlying face perception (using brain scanning, patient data, direct stimulation of the brain, visual adaptation and single-cell recording), and (iii) comparative aspects of face perception (comparing adult human abilities with those of chimpanzees and children). Here, we introduce the central themes of the issue and present an overview of the articles.

  17. Learning Compact Binary Face Descriptor for Face Recognition.

    PubMed

    Lu, Jiwen; Liong, Venice Erin; Zhou, Xiuzhuang; Zhou, Jie

    2015-10-01

    Binary feature descriptors such as local binary patterns (LBP) and its variations have been widely used in many face recognition systems due to their excellent robustness and strong discriminative power. However, most existing binary face descriptors are hand-crafted, which require strong prior knowledge to engineer them by hand. In this paper, we propose a compact binary face descriptor (CBFD) feature learning method for face representation and recognition. Given each face image, we first extract pixel difference vectors (PDVs) in local patches by computing the difference between each pixel and its neighboring pixels. Then, we learn a feature mapping to project these pixel difference vectors into low-dimensional binary vectors in an unsupervised manner, where 1) the variance of all binary codes in the training set is maximized, 2) the loss between the original real-valued codes and the learned binary codes is minimized, and 3) binary codes evenly distribute at each learned bin, so that the redundancy information in PDVs is removed and compact binary codes are obtained. Lastly, we cluster and pool these binary codes into a histogram feature as the final representation for each face image. Moreover, we propose a coupled CBFD (C-CBFD) method by reducing the modality gap of heterogeneous faces at the feature level to make our method applicable to heterogeneous face recognition. Extensive experimental results on five widely used face datasets show that our methods outperform state-of-the-art face descriptors.

  18. Micromachine Wedge Stepping Motor

    SciTech Connect

    Allen, J.J.; Schriner, H.K.

    1998-11-04

    A wedge stepping motor, which will index a mechanism, has been designed and fabricated in the surface rnicromachine SUMMiT process. This device has demonstrated the ability to index one gear tooth at a time with speeds up to 205 teeth/see. The wedge stepper motor has the following features, whi:h will be useful in a number of applications. o The ability to precisely position mechanical components. . Simple pulse signals can be used for operation. o Only 2 drive signals are requixed for operation. o Torque and precision capabilities increase with device size . The device to be indexed is restrained at all times by the wedge shaped tooth that is used for actuation. This paper will discuss the theory of operation and desi=m of the wedge stepping motor. The fabrication and testing of I he device will also be presented.

  19. The digital step edge

    NASA Technical Reports Server (NTRS)

    Haralick, R. M.

    1982-01-01

    The facet model was used to accomplish step edge detection. The essence of the facet model is that any analysis made on the basis of the pixel values in some neighborhood has its final authoritative interpretation relative to the underlying grey tone intensity surface of which the neighborhood pixel values are observed noisy samples. Pixels which are part of regions have simple grey tone intensity surfaces over their areas. Pixels which have an edge in them have complex grey tone intensity surfaces over their areas. Specially, an edge moves through a pixel only if there is some point in the pixel's area having a zero crossing of the second directional derivative taken in the direction of a non-zero gradient at the pixel's center. To determine whether or not a pixel should be marked as a step edge pixel, its underlying grey tone intensity surface was estimated on the basis of the pixels in its neighborhood.

  20. Step Prototype Development Status

    NASA Astrophysics Data System (ADS)

    Mehls, C.; Bayart, C.; Bower, J.; Clarke, B.; Cox, C.; Gill, D.; Stricker, D.; Vora, N.; Wang, S.; Zhou, P.; Torii, R.; Worden, P.; Debra, D.; Dittus, H.; Loeffler, F.

    2008-09-01

    STEP, the Satellite Test of the Equivalence Principle [1], proposes to test the Equivalence Principle to a part in 1018 by comparing the free-fall acceleration of cylindrical shaped test masses [2] in Earth orbit. Magnetic bearings constrain the test mass motion to their axis of symmetry [3]. The displacement of the test masses is measured using a DC SQUID and superconducting coils [4], enabling a displacement sensitivity as small as 10-15 m. In combination with a small spring stiffness a differential acceleration sensitivity of 10-18 g is achievable. Residual satellite acceleration is reduced to better than 10-14 g by compensating satellite drag forces with thrust provided by helium gas. We report on recent progress in the development of STEP prototype flight accelerometers, in particular the development of the high precision quartz housing for the engineering inner accelerometer and the testing of SQUID and capacitive readout systems using 'brass board' accelerometer prototypes.

  1. GAYE: a face recognition system

    NASA Astrophysics Data System (ADS)

    Kepenekci, Burcu; Tek, F. Boray; Cilingir, Onur; Sakarya, Ufuk; Akar, Gozde B.

    2004-05-01

    In this paper, a new face recognition system, GAYE, is presented. GAYE is a fully automatic system that detects and recognizes faces in cluttered scenes. The input of the system is any digitized image/image sequence that includes face/faces. The basic building blocks of the system are face detection, feature extraction and feature comparison. Face detection is based on skin color segmentation. For feature extraction, a novel approach is proposed that depends on the Gabor wavelet transform of the face image. By comparing facial feature vectors system finally makes a decision if the incoming person is recognized or not. Real time system tests show that GAYE achieves a recognition ratio over %90.

  2. [Comparative studies of face recognition].

    PubMed

    Kawai, Nobuyuki

    2012-07-01

    Every human being is proficient in face recognition. However, the reason for and the manner in which humans have attained such an ability remain unknown. These questions can be best answered-through comparative studies of face recognition in non-human animals. Studies in both primates and non-primates show that not only primates, but also non-primates possess the ability to extract information from their conspecifics and from human experimenters. Neural specialization for face recognition is shared with mammals in distant taxa, suggesting that face recognition evolved earlier than the emergence of mammals. A recent study indicated that a social insect, the golden paper wasp, can distinguish their conspecific faces, whereas a closely related species, which has a less complex social lifestyle with just one queen ruling a nest of underlings, did not show strong face recognition for their conspecifics. Social complexity and the need to differentiate between one another likely led humans to evolve their face recognition abilities.

  3. Developmental processes in face perception

    PubMed Central

    Dahl, Christoph D.; Rasch, Malte J.; Tomonaga, Masaki; Adachi, Ikuma

    2013-01-01

    Understanding the developmental origins of face recognition has been the goal of many studies of various approaches. Contributions of experience-expectant mechanisms (early component), like perceptual narrowing, and lifetime experience (late component) to face processing remain elusive. By investigating captive chimpanzees of varying age, a rare case of a species with lifelong exposure to non-conspecific faces at distinctive levels of experience, we can disentangle developmental components in face recognition. We found an advantage in discriminating chimpanzee above human faces in young chimpanzees, reflecting a predominant contribution of an early component that drives the perceptual system towards the conspecific morphology, and an advantage for human above chimpanzee faces in old chimpanzees, reflecting a predominant late component that shapes the perceptual system along the critical dimensions of the face exposed to. We simulate the contribution of early and late components using computational modeling and mathematically describe the underlying functions. PMID:23304435

  4. Step Bunching: Influence of Impurities and Solution Flow

    NASA Technical Reports Server (NTRS)

    Chernov, A. A.; Vekilov, P. G.; Coriell, S. R.; Murray, B. T.; McFadden, G. B.

    1999-01-01

    Step bunching results in striations even at relatively early stages of its development and in inclusions of mother liquor at the later stages. Therefore, eliminating step bunching is crucial for high crystal perfection. At least 5 major effects causing and influencing step bunching are known: (1) Basic morphological instability of stepped interfaces. It is caused by concentration gradient in the solution normal to the face and by the redistribution of solute tangentially to the interface which redistribution enhances occasional perturbations in step density due to various types of noise; (2) Aggravation of the above basic instability by solution flowing tangentially to the face in the same directions as the steps or stabilization of equidistant step train if these flows are antiparallel; (3) Enhanced bunching at supersaturation where step velocity v increases with relative supersaturation s much faster than linear. This v(s) dependence is believed to be associated with impurities. The impurities of which adsorption time is comparable with the time needed to deposit one lattice layer may also be responsible for bunching; (4) Very intensive solution flow stabilizes growing interface even at parallel solution and step flows; (5) Macrosteps were observed to nucleate at crystal corners and edges. Numerical simulation, assuming step-step interactions via surface diffusion also show that step bunching may be induced by random step nucleation at the facet edge and by discontinuity in the step density (a ridge) somewhere in the middle of a face. The corresponding bunching patterns produce the ones observed in experiment. The nature of step bunching generated at the corners and edges and by dislocation step sources, as well as the also relative importance and interrelations between mechanisms 1-5 is not clear, both from experimental and theoretical standpoints. Furthermore, several laws controlling the evolution of existing step bunches have been suggested, though

  5. Effects of the computational time step on numerical solutions for turbulent flow

    NASA Technical Reports Server (NTRS)

    Choi, Haecheon; Moin, Parviz

    1994-01-01

    Effects of large computational time steps on the computed turbulence were investigated using a fully implicit method. In turbulent channel flow computations the largest computational time step in wall units which led to accurate prediction of turbulence statistics was determined. Turbulence fluctuations could not be sustained if the computational time step was near or larger than the Kolmogorov time scale.

  6. The construction FACE database - Codifying the NIOSH FACE reports.

    PubMed

    Dong, Xiuwen Sue; Largay, Julie A; Wang, Xuanwen; Cain, Chris Trahan; Romano, Nancy

    2017-09-01

    The National Institute for Occupational Safety and Health (NIOSH) has published reports detailing the results of investigations on selected work-related fatalities through the Fatality Assessment and Control Evaluation (FACE) program since 1982. Information from construction-related FACE reports was coded into the Construction FACE Database (CFD). Use of the CFD was illustrated by analyzing major CFD variables. A total of 768 construction fatalities were included in the CFD. Information on decedents, safety training, use of PPE, and FACE recommendations were coded. Analysis shows that one in five decedents in the CFD died within the first two months on the job; 75% and 43% of reports recommended having safety training or installing protection equipment, respectively. Comprehensive research using FACE reports may improve understanding of work-related fatalities and provide much-needed information on injury prevention. The CFD allows researchers to analyze the FACE reports quantitatively and efficiently. Copyright © 2017 Elsevier Ltd and National Safety Council. All rights reserved.

  7. Contributions of individual face features to face discrimination.

    PubMed

    Logan, Andrew J; Gordon, Gael E; Loffler, Gunter

    2017-08-01

    Faces are highly complex stimuli that contain a host of information. Such complexity poses the following questions: (a) do observers exhibit preferences for specific information? (b) how does sensitivity to individual face parts compare? These questions were addressed by quantifying sensitivity to different face features. Discrimination thresholds were determined for synthetic faces under the following conditions: (i) 'full face': all face features visible; (ii) 'isolated feature': single feature presented in isolation; (iii) 'embedded feature': all features visible, but only one feature modified. Mean threshold elevations for isolated features, relative to full-faces, were 0.84x, 1.08, 2.12, 3.34, 4.07 and 4.47 for head-shape, hairline, nose, mouth, eyes and eyebrows respectively. Hence, when two full faces can be discriminated at threshold, the difference between the eyes is about four times less than what is required when discriminating between isolated eyes. In all cases, sensitivity was higher when features were presented in isolation than when they were embedded within a face context (threshold elevations of 0.94x, 1.74, 2.67, 2.90, 5.94 and 9.94). This reveals a specific pattern of sensitivity to face information. Observers are between two and four times more sensitive to external than internal features. The pattern for internal features (higher sensitivity for the nose, compared to mouth, eyes and eyebrows) is consistent with lower sensitivity for those parts affected by facial dynamics (e.g. facial expressions). That isolated features are easier to discriminate than embedded features supports a holistic face processing mechanism which impedes extraction of information about individual features from full faces. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The Psychology of Channeling.

    ERIC Educational Resources Information Center

    Corey, Michael A.

    1988-01-01

    Theoretically analyzes phenomenon of channeling from perspective of C. G. Jung's analytic psychology. Hypothesizes that contact with otherworldly spiritual beings claimed by channelers is actually projected contact with contents of channeler's own unconscious mind. Suggests that channelers seek more constructive ways of contacting their…

  9. [A review of face illusions].

    PubMed

    Kitaoka, Akiyoshi

    2012-07-01

    A variety of "face illusions," including the gaze illusion, face inversion effects, geometrical illusions, reversible figures, and other interesting phenomena related to face perception, are reviewed in the present report, with many sample images. The "gaze illusion" or the illusion of eye direction includes the Wollaston illusion, the luminance-induced gaze shift, the Bogart illusion, the eye-shadow-dependent gaze illusion, the Mona Lisa effect, etc. "Face inversion effects" refer to the Thatcher illusion, the fat face-thin illusion, underestimation of the upright face, the nose-shortening illusion of the inverted face, etc. "Geometrical illusions" include the Lee-Freire illusion, Yang's iris illusion, overestimation of the farther eye, the eye-shadow-dependent eye-size illusion, etc. "Reversible figures" contain the whole-part reversible figure, Rubin's vase-face illusion, or hybrid images. "Other interesting phenomena" include the flashed face distortion effect, the presidential illusion, predominance of the mouth or eyebrows over eye expression, the eye direction aftereffect, etc. It is suggested that some of these phenomena are highly specific to face perception.

  10. Adaptation improves face trustworthiness discrimination.

    PubMed

    Keefe, B D; Dzhelyova, M; Perrett, D I; Barraclough, N E

    2013-01-01

    Adaptation to facial characteristics, such as gender and viewpoint, has been shown to both bias our perception of faces and improve facial discrimination. In this study, we examined whether adapting to two levels of face trustworthiness improved sensitivity around the adapted level. Facial trustworthiness was manipulated by morphing between trustworthy and untrustworthy prototypes, each generated by morphing eight trustworthy and eight untrustworthy faces, respectively. In the first experiment, just-noticeable differences (JNDs) were calculated for an untrustworthy face after participants adapted to an untrustworthy face, a trustworthy face, or did not adapt. In the second experiment, the three conditions were identical, except that JNDs were calculated for a trustworthy face. In the third experiment we examined whether adapting to an untrustworthy male face improved discrimination to an untrustworthy female face. In all experiments, participants completed a two-interval forced-choice (2-IFC) adaptive staircase procedure, in which they judged which face was more untrustworthy. JNDs were derived from a psychometric function fitted to the data. Adaptation improved sensitivity to faces conveying the same level of trustworthiness when compared to no adaptation. When adapting to and discriminating around a different level of face trustworthiness there was no improvement in sensitivity and JNDs were equivalent to those in the no adaptation condition. The improvement in sensitivity was found to occur even when adapting to a face with different gender and identity. These results suggest that adaptation to facial trustworthiness can selectively enhance mechanisms underlying the coding of facial trustworthiness to improve perceptual sensitivity. These findings have implications for the role of our visual experience in the decisions we make about the trustworthiness of other individuals.

  11. Adaptation improves face trustworthiness discrimination

    PubMed Central

    Keefe, B. D.; Dzhelyova, M.; Perrett, D. I.; Barraclough, N. E.

    2013-01-01

    Adaptation to facial characteristics, such as gender and viewpoint, has been shown to both bias our perception of faces and improve facial discrimination. In this study, we examined whether adapting to two levels of face trustworthiness improved sensitivity around the adapted level. Facial trustworthiness was manipulated by morphing between trustworthy and untrustworthy prototypes, each generated by morphing eight trustworthy and eight untrustworthy faces, respectively. In the first experiment, just-noticeable differences (JNDs) were calculated for an untrustworthy face after participants adapted to an untrustworthy face, a trustworthy face, or did not adapt. In the second experiment, the three conditions were identical, except that JNDs were calculated for a trustworthy face. In the third experiment we examined whether adapting to an untrustworthy male face improved discrimination to an untrustworthy female face. In all experiments, participants completed a two-interval forced-choice (2-IFC) adaptive staircase procedure, in which they judged which face was more untrustworthy. JNDs were derived from a psychometric function fitted to the data. Adaptation improved sensitivity to faces conveying the same level of trustworthiness when compared to no adaptation. When adapting to and discriminating around a different level of face trustworthiness there was no improvement in sensitivity and JNDs were equivalent to those in the no adaptation condition. The improvement in sensitivity was found to occur even when adapting to a face with different gender and identity. These results suggest that adaptation to facial trustworthiness can selectively enhance mechanisms underlying the coding of facial trustworthiness to improve perceptual sensitivity. These findings have implications for the role of our visual experience in the decisions we make about the trustworthiness of other individuals. PMID:23801979

  12. 'Lysi-T-FACE

    NASA Astrophysics Data System (ADS)

    Herndl, Markus; Pötsch, Erich; Kandolf, Matthias; Bohner, Andreas; Schaumberger, Andreas; Resch, Reinhard; Graiss, Wilhelm; Krautzer, Bernhard; Buchgraber, Karl

    2010-05-01

    During the past century the average global surface air temperature has already increased by 1°C. A doubling of atmospheric concentration of CO2 near the end of the 21st century is predicted to result in a 3°C temperature increase. The Alpine region has experienced above average warming over the last century and is considered particularly vulnerable to global change. In Austria in some regions, grassland production suffered severe droughts during the last decade leading to serious damages and even temporal shortage in feed supply. Changes in temperature and precipitation have evident consequences for grassland vegetation. Increasing atmospheric CO2 concentration is a major driver of climate change. Photosynthesis and productivity of most grassland species might be stimulated by increasing CO2 when soil nutrients and water are not limiting. On dry grassland sites increasing CO2 also reduces plant water loss, thereby increasing plant water use efficiency. When plant production is limited by seasonal cold temperatures as e.g. in the inner Alpine parts of Austria and in high altitude or high latitude grasslands, combined warming and higher CO2 might continue to enhance plant production. However, it is still unknown to what extend a further increase of temperature and CO2 will result in higher biomass yield in different grassland communities. To study the effects of global warming on future grassland communities and management, the application of a heating treatment combined with free-air controlled enhancement of CO2 (T-FACE) to open-field plant canopies at lysimeters is an innovative approach which allows studying responses of the plant-soil-systems as well as carbon- water and nutrient fluxes under expected future climate. The experiment is scheduled to run in the first phase 6 years (2011-2017) and is located at the AREC Raumberg-Gumpenstein, Upper Enns Valley, Austria (47,49; 14,10). Heater arrays and miniFACE rings are installed in 1.6 m diameter plots and expose

  13. Face-n-Food: Gender Differences in Tuning to Faces

    PubMed Central

    Pavlova, Marina A.; Scheffler, Klaus; Sokolov, Alexander N.

    2015-01-01

    Faces represent valuable signals for social cognition and non-verbal communication. A wealth of research indicates that women tend to excel in recognition of facial expressions. However, it remains unclear whether females are better tuned to faces. We presented healthy adult females and males with a set of newly created food-plate images resembling faces (slightly bordering on the Giuseppe Arcimboldo style). In a spontaneous recognition task, participants were shown a set of images in a predetermined order from the least to most resembling a face. Females not only more readily recognized the images as a face (they reported resembling a face on images, on which males still did not), but gave on overall more face responses. The findings are discussed in the light of gender differences in deficient face perception. As most neuropsychiatric, neurodevelopmental and psychosomatic disorders characterized by social brain abnormalities are sex specific, the task may serve as a valuable tool for uncovering impairments in visual face processing. PMID:26154177

  14. About-face on face recognition ability and holistic processing

    PubMed Central

    Richler, Jennifer J.; Floyd, R. Jackie; Gauthier, Isabel

    2015-01-01

    Previous work found a small but significant relationship between holistic processing measured with the composite task and face recognition ability measured by the Cambridge Face Memory Test (CFMT; Duchaine & Nakayama, 2006). Surprisingly, recent work using a different measure of holistic processing (Vanderbilt Holistic Face Processing Test [VHPT-F]; Richler, Floyd, & Gauthier, 2014) and a larger sample found no evidence for such a relationship. In Experiment 1 we replicate this unexpected result, finding no relationship between holistic processing (VHPT-F) and face recognition ability (CFMT). A key difference between the VHPT-F and other holistic processing measures is that unique face parts are used on each trial in the VHPT-F, unlike in other tasks where a small set of face parts repeat across the experiment. In Experiment 2, we test the hypothesis that correlations between the CFMT and holistic processing tasks are driven by stimulus repetition that allows for learning during the composite task. Consistent with our predictions, CFMT performance was correlated with holistic processing in the composite task when a small set of face parts repeated over trials, but not when face parts did not repeat. A meta-analysis confirms that relationships between the CFMT and holistic processing depend on stimulus repetition. These results raise important questions about what is being measured by the CFMT, and challenge current assumptions about why faces are processed holistically. PMID:26223027

  15. Step proof mass dynamics

    NASA Astrophysics Data System (ADS)

    Wiegand, M.; Scheithauer, S.; Theil, S.

    2004-05-01

    The Satellite Test of Equivalence Principle (STEP) is a joint European-US project to investigate one of the most fundamental principles in physics, the Equivalence of inertia and passive gravitational mass. As STEP matures into a flight program, the development of a precise spacecraft dynamics simulator becomes crucial. The simulator is primarily needed for design, test and verification of the drag-free control (DFC) system and the flight software. The drag-free concept involves centering the proof mass located inside a satellite. As the proof mass is free of external disturbances (drag free), it follows a purely gravitational orbit. Since the satellite is forced to follow the proof mass, it too follows the same gravitational orbit, canceling all non-gravitational forces. For the STEP Mission, the DFC system is required to attenuate any disturbance forces acting on the spacecraft to achieve residual acceleration at location of the accelerometer of less than 3×10 -14 m/s2 (rms) across the measurement bandwidth. While the simulator is based on a high-fidelity six-degree-of-freedom numerical simulation, a simplified model is used to analyze the proof mass dynamics. The stability analysis of the proof mass motion is performed by transformation of the simplified model into the standard form of the Mathieu differential equation. The stability regions of the solution are applied to choose proper values for parameters like coupling forces between satellite and proof mass as a function of spacecraft rotation. The paper describes the calculation of the spacecraft/payload dynamics and the assumptions used to derive the underlying algorithms with a special emphasis on numerical precision issues.

  16. A Reconfigurable Stepping Motor

    NASA Astrophysics Data System (ADS)

    Rogers, Charles; Selvaggi, Richard

    2009-04-01

    Multiphase brushless actuators, commonly known as the stepper motors, are ubiquitous for many precision control applications. Developments in the microelectronics have lead to their use as efficient drive motors for modern electric vehicles. Understanding the physics and the control logic for interfacing these transducers continues to be important for scientists and engineers. An overview of the stepping motor principles and interfacing requirements is presented and a simple working model used to teach the concepts of stepper motors is described and demonstrated. This model was used to design a much larger stepper motor required to precisely rotate a massive optical system in the undergraduate advanced physics laboratory.

  17. Steps to the moon

    USGS Publications Warehouse

    ,; Dale, Alvin E.

    1976-01-01

    On July 20, 1969, man walked on the surface of the Moon and began a new chapter of his studies that will eventually disclose the geologic nature of the Earth's nearest neighbor. Although he has finally reached the Moon and sampled its substance, much work and study remain before he will know the full scientific significance of the first landing. This booklet briefly summarizes the steps man has taken to understand the Moon and what he thinks he has learned to date as a result of his centuries-long speculations and studies.

  18. New photolithography stepping machine

    SciTech Connect

    Hale, L.; Klingmann, J.; Markle, D.

    1995-03-08

    A joint development project to design a new photolithography steeping machine capable of 150 nanometer overlay accuracy was completed by Ultratech Stepper and the Lawrence Livermore National Laboratory. The principal result of the project is a next-generation product that will strengthen the US position in step-and-repeat photolithography. The significant challenges addressed and solved in the project are the subject of this report. Design methods and new devices that have broader application to precision machine design are presented in greater detail while project specific information serves primarily as background and motivation.

  19. Faces of Pluto

    NASA Image and Video Library

    2015-06-11

    These images, taken by NASA's New Horizons' Long Range Reconnaissance Imager (LORRI), show four different "faces" of Pluto as it rotates about its axis with a period of 6.4 days. All the images have been rotated to align Pluto's rotational axis with the vertical direction (up-down) on the figure, as depicted schematically in the upper left. From left to right, the images were taken when Pluto's central longitude was 17, 63, 130, and 243 degrees, respectively. The date of each image, the distance of the New Horizons spacecraft from Pluto, and the number of days until Pluto closest approach are all indicated in the figure.These images show dramatic variations in Pluto's surface features as it rotates. When a very large, dark region near Pluto's equator appears near the limb, it gives Pluto a distinctly, but false, non-spherical appearance. Pluto is known to be almost perfectly spherical from previous data. These images are displayed at four times the native LORRI image size, and have been processed using a method called deconvolution, which sharpens the original images to enhance features on Pluto. Deconvolution can occasionally introduce "false" details, so the finest details in these pictures will need to be confirmed by images taken from closer range in the next few weeks. All of the images are displayed using the same brightness scale. http://photojournal.jpl.nasa.gov/catalog/PIA19686

  20. Facing the Spectator

    PubMed Central

    Koenderink, Jan; van Doorn, Andrea; Pinna, Baingio

    2016-01-01

    We investigated the familiar phenomenon of the uncanny feeling that represented people in frontal pose invariably appear to “face you” from wherever you stand. We deploy two different methods. The stimuli include the conventional one—a flat portrait rocking back and forth about a vertical axis—augmented with two novel variations. In one alternative, the portrait frame rotates whereas the actual portrait stays motionless and fronto-parallel; in the other, we replace the (flat!) portrait with a volumetric object. These variations yield exactly the same optical stimulation in frontal view, but become grossly different in very oblique views. We also let participants sample their momentary awareness through “gauge object” settings in static displays. From our results, we conclude that the psychogenesis of visual awareness maintains a number—at least two, but most likely more—of distinct spatial frameworks simultaneously involving “cue–scission.” Cues may be effective in one of these spatial frameworks but ineffective or functionally different in other ones. PMID:27895885

  1. Facing the Spectator.

    PubMed

    Koenderink, Jan; van Doorn, Andrea; Pinna, Baingio; Pepperell, Robert

    2016-01-01

    We investigated the familiar phenomenon of the uncanny feeling that represented people in frontal pose invariably appear to "face you" from wherever you stand. We deploy two different methods. The stimuli include the conventional one-a flat portrait rocking back and forth about a vertical axis-augmented with two novel variations. In one alternative, the portrait frame rotates whereas the actual portrait stays motionless and fronto-parallel; in the other, we replace the (flat!) portrait with a volumetric object. These variations yield exactly the same optical stimulation in frontal view, but become grossly different in very oblique views. We also let participants sample their momentary awareness through "gauge object" settings in static displays. From our results, we conclude that the psychogenesis of visual awareness maintains a number-at least two, but most likely more-of distinct spatial frameworks simultaneously involving "cue-scission." Cues may be effective in one of these spatial frameworks but ineffective or functionally different in other ones.

  2. Channel nut tool

    DOEpatents

    Olson, Marvin

    2016-01-12

    A method, system, and apparatus for installing channel nuts includes a shank, a handle formed on a first end of a shank, and an end piece with a threaded shaft configured to receive a channel nut formed on the second end of the shaft. The tool can be used to insert or remove a channel nut in a channel framing system and then removed from the channel nut.

  3. Dissipating Step Bunches during Crystallization under Transport Control

    NASA Technical Reports Server (NTRS)

    Lin, Hong; Yau, S.-T.; Vekilov, Peter, G.

    2003-01-01

    In studies of crystal formation by the generation and spreading of layers, equidistant step trains are considered unstable---bunches and other spatiotemporal patterns of the growth steps are viewed as ubiquitous. We provide an example to the opposite. We monitor the spatiotemporal dynamics of steps and the resulting step patterns during crystallization of the proteins ferritin and apoferritin using the atomic force microscope. The variations in step velocity and density are not correlated, indicating the lack of a long-range attraction between the steps. We show that (i) because of its coupling to bulk transport, nucleation of new layers is chaotic and occurs at the facet edges, where the interfacial supersaturation is higher; (ii) step bunches self-organize via the competition for supply from the solution; and, (iii) bunches of weakly interacting steps decay as they move along the face. Tests by numerical modeling support the conclusions about the mechanisms underlying our observations. The results from these systems suggest that during crystallization controlled by transport, with weakly or noninteracting growth steps, the stable kinetic state of the surface is an equidistant step train, and step bunches only arise during nucleation of new layers. Since nucleation only occurs at a few sites on the surface, the surface morphology may be controllably patterned or smoothened by locally controlling nucleation.

  4. Dissipating Step Bunches during Crystallization under Transport Control

    NASA Technical Reports Server (NTRS)

    Lin, Hong; Yau, S.-T.; Vekilov, Peter, G.

    2003-01-01

    In studies of crystal formation by the generation and spreading of layers, equidistant step trains are considered unstable---bunches and other spatiotemporal patterns of the growth steps are viewed as ubiquitous. We provide an example to the opposite. We monitor the spatiotemporal dynamics of steps and the resulting step patterns during crystallization of the proteins ferritin and apoferritin using the atomic force microscope. The variations in step velocity and density are not correlated, indicating the lack of a long-range attraction between the steps. We show that (i) because of its coupling to bulk transport, nucleation of new layers is chaotic and occurs at the facet edges, where the interfacial supersaturation is higher; (ii) step bunches self-organize via the competition for supply from the solution; and, (iii) bunches of weakly interacting steps decay as they move along the face. Tests by numerical modeling support the conclusions about the mechanisms underlying our observations. The results from these systems suggest that during crystallization controlled by transport, with weakly or noninteracting growth steps, the stable kinetic state of the surface is an equidistant step train, and step bunches only arise during nucleation of new layers. Since nucleation only occurs at a few sites on the surface, the surface morphology may be controllably patterned or smoothened by locally controlling nucleation.

  5. Evolutionary-Rough Feature Selection for Face Recognition

    NASA Astrophysics Data System (ADS)

    Mazumdar, Debasis; Mitra, Soma; Mitra, Sushmita

    Elastic Bunch Graph Matching is a feature-based face recognition algorithm which has been used to determine facial attributes from an image. However the dimension of the feature vectors, in case of EBGM, is quite high. Feature selection is a useful preprocessing step for reducing dimensionality, removing irrelevant data, improving learning accuracy and enhancing output comprehensibility.

  6. Holistic face training enhances face processing in developmental prosopagnosia.

    PubMed

    DeGutis, Joseph; Cohan, Sarah; Nakayama, Ken

    2014-06-01

    Prosopagnosia has largely been regarded as an untreatable disorder. However, recent case studies using cognitive training have shown that it is possible to enhance face recognition abilities in individuals with developmental prosopagnosia. Our goal was to determine if this approach could be effective in a larger population of developmental prosopagnosics. We trained 24 developmental prosopagnosics using a 3-week online face-training program targeting holistic face processing. Twelve subjects with developmental prosopagnosia were assessed before and after training, and the other 12 were assessed before and after a waiting period, they then performed the training, and were then assessed again. The assessments included measures of front-view face discrimination, face discrimination with view-point changes, measures of holistic face processing, and a 5-day diary to quantify potential real-world improvements. Compared with the waiting period, developmental prosopagnosics showed moderate but significant overall training-related improvements on measures of front-view face discrimination. Those who reached the more difficult levels of training ('better' trainees) showed the strongest improvements in front-view face discrimination and showed significantly increased holistic face processing to the point of being similar to that of unimpaired control subjects. Despite challenges in characterizing developmental prosopagnosics' everyday face recognition and potential biases in self-report, results also showed modest but consistent self-reported diary improvements. In summary, we demonstrate that by using cognitive training that targets holistic processing, it is possible to enhance face perception across a group of developmental prosopagnosics and further suggest that those who improved the most on the training task received the greatest benefits.

  7. Holistic face training enhances face processing in developmental prosopagnosia

    PubMed Central

    Cohan, Sarah; Nakayama, Ken

    2014-01-01

    Prosopagnosia has largely been regarded as an untreatable disorder. However, recent case studies using cognitive training have shown that it is possible to enhance face recognition abilities in individuals with developmental prosopagnosia. Our goal was to determine if this approach could be effective in a larger population of developmental prosopagnosics. We trained 24 developmental prosopagnosics using a 3-week online face-training program targeting holistic face processing. Twelve subjects with developmental prosopagnosia were assessed before and after training, and the other 12 were assessed before and after a waiting period, they then performed the training, and were then assessed again. The assessments included measures of front-view face discrimination, face discrimination with view-point changes, measures of holistic face processing, and a 5-day diary to quantify potential real-world improvements. Compared with the waiting period, developmental prosopagnosics showed moderate but significant overall training-related improvements on measures of front-view face discrimination. Those who reached the more difficult levels of training (‘better’ trainees) showed the strongest improvements in front-view face discrimination and showed significantly increased holistic face processing to the point of being similar to that of unimpaired control subjects. Despite challenges in characterizing developmental prosopagnosics’ everyday face recognition and potential biases in self-report, results also showed modest but consistent self-reported diary improvements. In summary, we demonstrate that by using cognitive training that targets holistic processing, it is possible to enhance face perception across a group of developmental prosopagnosics and further suggest that those who improved the most on the training task received the greatest benefits. PMID:24691394

  8. The Industrial Base: Facing Extinction

    DTIC Science & Technology

    1992-03-10

    INDUSTRIAL BASE.. FACING EXTINCTION ., TIc LECTE BY UN02 1992 - MR. DAVID L. THOMAS Department of the Army Civilian , 4...Industrial Base: Facing Extinction 12. PERSONAL AUTHOR(S) David L. Thomas, DAC, GM-15 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month...service or government agency. The Industrial Base: Accesioti For Facing Extinction NTIS CRA&IDTIC TAB D] Uanc,ounced 0 Justification AN INDIVIDUAL

  9. Fast and robust Face Detection

    NASA Astrophysics Data System (ADS)

    Anisetti, Marco

    This chapter presents a fully automatic face detection system robust to moderate change in expression, posture and illumination. The final goal of this detection is to initialize a 3D face tracking, therefore is specialized for working on videos of good quality instead of still images. More in details we present two different face detection strategy based on slightly modified largely used Viola-Jones [1] object detector.

  10. SPAR-H Step-by-Step Guidance

    SciTech Connect

    W. J. Galyean; A. M. Whaley; D. L. Kelly; R. L. Boring

    2011-05-01

    This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

  11. The Kent Face Matching Test.

    PubMed

    Fysh, Matthew C; Bindemann, Markus

    2017-09-05

    This study presents the Kent Face Matching Test (KFMT), which comprises 200 same-identity and 20 different-identity pairs of unfamiliar faces. Each face pair consists of a photograph from a student ID card and a high-quality portrait that was taken at least three months later. The test is designed to complement existing resources for face-matching research, by providing a more ecologically valid stimulus set that captures the natural variability that can arise in a person's appearance over time. Two experiments are presented to demonstrate that the KFMT provides a challenging measure of face matching but correlates with established tests. Experiment 1 compares a short version of this test with the optimized Glasgow Face Matching Test (GFMT). In Experiment 2, a longer version of the KFMT, with infrequent identity mismatches, is correlated with performance on the Cambridge Face Memory Test (CFMT) and the Cambridge Face Perception Test (CFPT). The KFMT is freely available for use in face-matching research. © 2017 The British Psychological Society.

  12. Holistic processing predicts face recognition.

    PubMed

    Richler, Jennifer J; Cheung, Olivia S; Gauthier, Isabel

    2011-04-01

    The concept of holistic processing is a cornerstone of face-recognition research. In the study reported here, we demonstrated that holistic processing predicts face-recognition abilities on the Cambridge Face Memory Test and on a perceptual face-identification task. Our findings validate a large body of work that relies on the assumption that holistic processing is related to face recognition. These findings also reconcile the study of face recognition with the perceptual-expertise work it inspired; such work links holistic processing of objects with people's ability to individuate them. Our results differ from those of a recent study showing no link between holistic processing and face recognition. This discrepancy can be attributed to the use in prior research of a popular but flawed measure of holistic processing. Our findings salvage the central role of holistic processing in face recognition and cast doubt on a subset of the face-perception literature that relies on a problematic measure of holistic processing.

  13. Matching faces with emotional expressions.

    PubMed

    Chen, Wenfeng; Lander, Karen; Liu, Chang Hong

    2011-01-01

    There is some evidence that faces with a happy expression are recognized better than faces with other expressions. However, little is known about whether this happy-face advantage also applies to perceptual face matching, and whether similar differences exist among other expressions. Using a sequential matching paradigm, we systematically compared the effects of seven basic facial expressions on identity recognition. Identity matching was quickest when a pair of faces had an identical happy/sad/neutral expression, poorer when they had a fearful/surprise/angry expression, and poorest when they had a disgust expression. Faces with a happy/sad/fear/surprise expression were matched faster than those with an anger/disgust expression when the second face in a pair had a neutral expression. These results demonstrate that effects of facial expression on identity recognition are not limited to happy-faces when a learned face is immediately tested. The results suggest different influences of expression in perceptual matching and long-term recognition memory.

  14. Cyber- and Face-to-Face Bullying: Who Crosses Over?

    ERIC Educational Resources Information Center

    Shin, Hwayeon Helene; Braithwaite, Valerie; Ahmed, Eliza

    2016-01-01

    A total of 3956 children aged 12-13 years who completed the Longitudinal Study of Australian Children (LSAC Wave 5) were studied about their experiences of traditional face-to-face bullying and cyberbullying in the last month. In terms of prevalence, sixty percent of the sample had been involved in traditional bullying as the victim and/or the…

  15. Developing Leadership Skills: Online versus Face-to-Face

    ERIC Educational Resources Information Center

    Silbergh, David; Lennon, Kate

    2006-01-01

    Purpose: This paper seeks to present final results from an exploratory research project that aimed to compare and contrast the effectiveness of different delivery modes (especially online as opposed to face-to-face) when developing leadership skills in established managers. Design/methodology/approach: This study sought to identify whether…

  16. Teaching On-Line versus Face-to-Face.

    ERIC Educational Resources Information Center

    Smith, Glenn Gordon; Ferguson, David; Caris, Mieke

    2002-01-01

    Investigates and describes the current instructor experience of teaching college courses over the Web versus in face-to-face formats in terms of teaching strategies, social issues, and media effects. Discusses communication styles, relationship between students and instructors, instructor workload, and discussion patterns, and proposes a model…

  17. Effects of aging on face identification and holistic face processing.

    PubMed

    Konar, Yaroslav; Bennett, Patrick J; Sekuler, Allison B

    2013-08-09

    Several studies have shown that face identification accuracy is lower in older than younger adults. This effect of aging might be due to age differences in holistic processing, which is thought to be an important component of human face processing. Currently, however, there is conflicting evidence as to whether holistic face processing is impaired in older adults. The current study therefore re-examined this issue by measuring response accuracy in a 1-of-4 face identification task and the composite face effect (CFE), a common index of holistic processing, in older adults. Consistent with previous reports, we found that face identification accuracy was lower in older adults than in younger adults tested in the same task. We also found a significant CFE in older adults that was similar in magnitude to the CFE measured in younger subjects with the same task. Finally, we found that there was a significant positive correlation between the CFE and face identification accuracy. This last result differs from the results obtained in a previous study that used the same tasks and which found no evidence of an association between the CFE and face identification accuracy in younger adults. Furthermore, the age difference was found with subtraction-, regression-, and ratio-based estimates of the CFE. The current findings are consistent with previous claims that older adults rely more heavily on holistic processing to identify objects in conditions of limited processing resources. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Teaching On-Line versus Face-to-Face.

    ERIC Educational Resources Information Center

    Smith, Glenn Gordon; Ferguson, David; Caris, Mieke

    2002-01-01

    Investigates and describes the current instructor experience of teaching college courses over the Web versus in face-to-face formats in terms of teaching strategies, social issues, and media effects. Discusses communication styles, relationship between students and instructors, instructor workload, and discussion patterns, and proposes a model…

  19. Top management meets line employees face to face.

    PubMed

    Lindstrom, C C; Taylor, J H; Ellis, R L

    1980-01-01

    The communication gap between a hospital's top management and the line employees need not be an ever-widening chasm. St. Luke's Hospital of Kansas City, MO, has established a system that allows administrators and employees to meet face to face every month without destroying the hospital's essential chain of command.

  20. Cyber- and Face-to-Face Bullying: Who Crosses Over?

    ERIC Educational Resources Information Center

    Shin, Hwayeon Helene; Braithwaite, Valerie; Ahmed, Eliza

    2016-01-01

    A total of 3956 children aged 12-13 years who completed the Longitudinal Study of Australian Children (LSAC Wave 5) were studied about their experiences of traditional face-to-face bullying and cyberbullying in the last month. In terms of prevalence, sixty percent of the sample had been involved in traditional bullying as the victim and/or the…