WorldWideScience

Sample records for moderately high reynolds

  1. A geometry-adaptive IB-LBM for FSI problems at moderate and high Reynolds numbers

    Science.gov (United States)

    Tian, Fangbao; Xu, Lincheng; Young, John; Lai, Joseph C. S.

    2017-11-01

    An FSI framework combining the LBM and an improved IBM is introduced for FSI problems at moderate and high Reynolds numbers. In this framework, the fluid dynamics is obtained by the LBM. The FSI boundary conditions are handled by an improved IBM based on the feedback scheme where the feedback coefficient is mathematically derived and explicitly approximated. The Lagrangian force is divided into two parts: one is caused by the mismatching of the flow velocity and the boundary velocity at previous time step, and the other is caused by the boundary acceleration. Such treatment significantly enhances the numerical stability. A geometry-adaptive refinement is applied to provide fine resolution around the immersed geometries. The overlapping grids between two adjacent refinements consist of two layers. The movement of fluid-structure interfaces only causes adding or removing grids at the boundaries of refinements. Finally, the classic Smagorinsky large eddy simulation model is incorporated into the framework to model turbulent flows at relatively high Reynolds numbers. Several validation cases are conducted to verify the accuracy and fidelity of the present solver over a range of Reynolds numbers. Mr L. Xu acknowledges the support of the University International Postgraduate Award by University of New South Wales. Dr. F.-B. Tian is the recipient of an Australian Research Council Discovery Early Career Researcher Award (Project Number DE160101098).

  2. High Reynolds Number Turbulence

    National Research Council Canada - National Science Library

    Smits, Alexander J

    2007-01-01

    The objectives of the grant were to provide a systematic study to fill the gap between existing research on low Reynolds number turbulent flows to the kinds of turbulent flows encountered on full-scale vehicles...

  3. Assessment of the aerodynamic characteristics of thick airfoils in high Reynolds and moderate Ma numbers using CFD modeling

    International Nuclear Information System (INIS)

    Prospathopoulos, John M; Papadakis, Giorgos; Voutsinas, Spyros G; Diakakis, Kostas; Sieros, Giorgos; Chaviaropoulos, Takis K

    2014-01-01

    The aerodynamic characteristics of thick airfoils in high Reynolds number is assessed using two different CFD RANS solvers: the compressible MaPFlow and the incompressible CRES-flowNS-2D both equipped with the k-ω SST turbulence model. Validation is carried out by comparing simulations against existing high Reynolds experimental data for the NACA 63-018 airfoil in the range of -10° to 20°. The use of two different solvers aims on one hand at increasing the credibility in the results and on the other at quantifying the compressibility effects. Convergence of steady simulations is achieved within a mean range of -10° to 14° which refers to attached or light stall conditions. Over this range the simulations from the two codes are in good agreement. As stall gets deeper, steady convergence ceases and the simulations must switch to unsteady. Lift and drag oscillations are produced which increase in amplitude as the angle of attack increases. Finally in post stall, the average C L is found to decrease up to ∼24° or 32° for the FFA or the NACA 63-018 airfoils respectively, and then recover to higher values indicating a change in the unsteady features of the flow

  4. Heat transfer measurements on an incidence-tolerant low pressure turbine blade in a high speed linear cascade at low to moderate Reynolds numbers

    Science.gov (United States)

    Moualeu, Leolein Patrick Gouemeni

    Runway-independent aircraft are expected to be the future for short-haul flights by improving air transportation and reducing area congestion encountered in airports. The Vehicle Systems Program of NASA identified a Large Civil Tilt-Rotor, equipped with variable-speed power-turbine engines, as the best concept. At cruise altitude, the engine rotor-speed will be reduced by as much as the 50% of take-off speed. The large incidence variation in the low pressure turbine associated with the change in speed can be detrimental to the engine performance. Low pressure turbine blades in cruise altitude are more predisposed to develop regions of boundary layer separation. Typical phenomenon such as impinging wakes on downstream blades and mainstream turbulences enhance the complexity of the flow in low pressure turbines. It is therefore important to be able to understand the flow behavior to accurately predict the losses. Research facilities are seldom able to experimentally reproduce low Reynolds numbers at relevant engine Mach number. Having large incidence swing as an additional parameter in the investigation of the boundary layer development, on a low pressure turbine blade, makes this topic unique and as a consequence requires a unique facility to conduct the experimental research. The compressible flow wind tunnel facility at the University of North Dakota had been updated to perform steady state experiments on a modular-cascade, designed to replicate a large variation of the incidence angles. The high speed and low Reynolds number facility maintained a sealed and closed loop configuration for each incidence angle. The updated facility is capable to produce experimental Reynolds numbers as low as 45,000 and as high as 570,000 at an exit Mach number of 0.72. Pressure and surface temperature measurements were performed at these low pressure turbine conditions. The present thesis investigates the boundary layer development on the surface of an Incidence-tolerant blade. The

  5. Unsteady behavior of a confined jet in a cavity at moderate Reynolds numbers

    International Nuclear Information System (INIS)

    Bouchet, G; Climent, E

    2012-01-01

    Self-sustained oscillations in the sinuous mode are observed when a jet impinges on a rigid surface. Confined jet instability is experimentally and numerically investigated here at moderate Reynolds numbers. When the Reynolds number is varied, the dynamic response of the jet is unusual in comparison with that of similar configurations (hole-tone, jet edge, etc). Modal transitions are clearly detected when the Reynolds number is varied. However, these transitions result in a reduction of the frequency, which means that the wavelength grows with Reynolds number. Moreover, the instability that sets in at low Reynolds number, as a subcritical Hopf bifurcation, disappears only 25% above the threshold. Then, the flow becomes steady again and symmetric. This atypical behavior is compared with our previous study on a submerged fountain (Bouchet et al 2002 Europhys. Lett. 59 826). (paper)

  6. Direct numerical simulation of moderate-Reynolds-number flow past arrays of rotating spheres

    Science.gov (United States)

    Zhou, Qiang; Fan, Liang-Shih

    2015-07-01

    Direct numerical simulations with an immersed boundary-lattice Boltzmann method are used to investigate the effects of particle rotation on flows past random arrays of mono-disperse spheres at moderate particle Reynolds numbers. This study is an extension of a previous study of the authors [Q. Zhou and L.-S. Fan, "Direct numerical simulation of low-Reynolds-number flow past arrays of rotating spheres," J. Fluid Mech. 765, 396-423 (2015)] that explored the effects of particle rotation at low particle Reynolds numbers. The results of this study indicate that as the particle Reynolds number increases, the normalized Magnus lift force decreases rapidly when the particle Reynolds number is in the range lower than 50. For the particle Reynolds number greater than 50, the normalized Magnus lift force approaches a constant value that is invariant with solid volume fractions. The proportional dependence of the Magnus lift force on the rotational Reynolds number (based on the angular velocity and the diameter of the spheres) observed at low particle Reynolds numbers does not change in the present study, making the Magnus lift force another possible factor that can significantly affect the overall dynamics of fluid-particle flows other than the drag force. Moreover, it is found that both the normalized drag force and the normalized torque increase with the increase of the particle Reynolds number and the solid volume fraction. Finally, correlations for the drag force, the Magnus lift force, and the torque in random arrays of rotating spheres at arbitrary solids volume fractions, rotational Reynolds numbers, and particle Reynolds numbers are formulated.

  7. Partial Cavity Flows at High Reynolds Numbers

    Science.gov (United States)

    Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

    2009-11-01

    Partial cavity flows created for friction drag reduction were examined on a large-scale. Partial cavities were investigated at Reynolds numbers up to 120 million, and stable cavities with frictional drag reduction of more than 95% were attained at optimal conditions. The model used was a 3 m wide and 12 m long flat plate with a plenum on the bottom. To create the partial cavity, air was injected at the base of an 18 cm backwards-facing step 2.1 m from the leading edge. The geometry at the cavity closure was varied for different flow speeds to optimize the closure of the cavity. Cavity gas flux, thickness, frictional loads, and cavity pressures were measured over a range of flow speeds and air injection fluxes. High-speed video was used extensively to investigate the unsteady three dimensional cavity closure, the overall cavity shape and oscillations.

  8. Direct Numerical Simulation of Flows over an NACA-0012 Airfoil at Low and Moderate Reynolds Numbers

    Science.gov (United States)

    Balakumar, P.

    2017-01-01

    Direct numerical simulations (DNS) of flow over an NACA-0012 airfoil are performed at a low and a moderate Reynolds numbers of Re(sub c)=50 times10(exp 3) and 1times 10(exp 6). The angles of attack are 5 and 15 degrees at the low and the moderate Reynolds number cases respectively. The three-dimensional unsteady compressible Navier-Stokes equations are solved using higher order compact schemes. The flow field in the low Reynolds number case consists of a long separation bubble near the leading-edge region and an attached boundary layer on the aft part of the airfoil. The shear layer that formed in the separated region persisted up to the end of the airfoil. The roles of the turbulent diffusion, advection, and dissipation terms in the turbulent kinetic-energy balance equation change as the boundary layer evolves over the airfoil. In the higher Reynolds number case, the leading-edge separation bubble is very small in length and in height. A fully developed turbulent boundary layer is observed in a short distance downstream of the reattachment point. The boundary layer velocity near the wall gradually decreases along the airfoil. Eventually, the boundary layer separates near the trailing edge. The Reynolds stresses peak in the outer part of the boundary layer and the maximum amplitude also gradually increases along the chord.

  9. Reynolds number effects in a turbulent pipe flow for low to moderate Re

    NARCIS (Netherlands)

    Toonder, den J.M.J.; Nieuwstadt, F.T.M.

    1997-01-01

    We present in this paper high resolution, two-dimensional LDV measurements in a turbulent pipe flow of water over the Reynolds number range 500025000. Results for the turbulence statistics up to the fourth moment are presented, as well as power spectra in the near-wall region. These results clearly

  10. Flowing of supersonic underexpanded micro-jets in the range of moderate Reynolds numbers

    Science.gov (United States)

    Mironov, S. G.; Aniskin, V. M.; Maslov, A. A.

    2017-10-01

    The paper presents new experimental results on the simulation of supersonic underexpanded micro-jets by macro-jet in the range of moderate Reynolds numbers of air outflow from the nozzle. A correlation is shown between the variations in the Pitot pressure in the model micro-jet with variations in the length of the supersonic core of real the micro-jets. The results of experiments on the effect of humidity on the pulsation of mass flow rate in a micro-jet are presented.

  11. High Reynolds number flows using liquid and gaseous helium

    International Nuclear Information System (INIS)

    Donnelly, R.J.

    1991-01-01

    Consideration is given to liquid and gaseous helium as test fluids, high Reynolds number test requirements in low speed aerodynamics, the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF, water tunnels, flow visualization, the six component magnetic suspension system for wind tunnel testing, and recent aerodynamic measurements with magnetic suspension systems. Attention is also given to application of a flow visualization technique to a superflow experiment, experimental investigations of He II flows at high Reynolds numbers, a study of homogeneous turbulence in superfluid helium, and thermal convection in liquid helium

  12. Reducing high Reynolds number hydroacoustic noise using superhydrophobic coating

    International Nuclear Information System (INIS)

    Elboth, Thomas; Reif, Bjørn Anders Pettersson; Andreassen, Øyvind; Martell, Michael B

    2011-01-01

    The objective of this study is to assess and quantify the effect of a superhydrophobic surface coating on turbulence-generated flow noise. The study utilizes results obtained from high Reynolds-number full-scale flow noise measurements taken on a commercial seismic streamer and results from low Reynolds-number direct numerical simulations. It is shown that it is possible to significantly reduce both the frictional drag and the levels of the turbulence generated flow noise even at very high Reynolds-numbers. For instance, frequencies below 10 Hz a reduction in the flow noise level of nearly 50% was measured. These results can be attributed to a reduced level of shear stress and change in the kinematic structure of the turbulence, both of which occur in the immediate vicinity of the superhydrophobic surface.

  13. A nonperturbative approximation for the moderate Reynolds number Navier-Stokes equations.

    Science.gov (United States)

    Roper, Marcus; Brenner, Michael P

    2009-03-03

    The nonlinearity of the Navier-Stokes equations makes predicting the flow of fluid around rapidly moving small bodies highly resistant to all approaches save careful experiments or brute force computation. Here, we show how a linearization of the Navier-Stokes equations captures the drag-determining features of the flow and allows simplified or analytical computation of the drag on bodies up to Reynolds number of order 100. We illustrate the utility of this linearization in 2 practical problems that normally can only be tackled with sophisticated numerical methods: understanding flow separation in the flow around a bluff body and finding drag-minimizing shapes.

  14. A nonperturbative approximation for the moderate Reynolds number Navier–Stokes equations

    Science.gov (United States)

    Roper, Marcus; Brenner, Michael P.

    2009-01-01

    The nonlinearity of the Navier–Stokes equations makes predicting the flow of fluid around rapidly moving small bodies highly resistant to all approaches save careful experiments or brute force computation. Here, we show how a linearization of the Navier–Stokes equations captures the drag-determining features of the flow and allows simplified or analytical computation of the drag on bodies up to Reynolds number of order 100. We illustrate the utility of this linearization in 2 practical problems that normally can only be tackled with sophisticated numerical methods: understanding flow separation in the flow around a bluff body and finding drag-minimizing shapes. PMID:19211800

  15. A Cryogenic High-Reynolds Turbulence Experiment at CERN

    CERN Document Server

    Bézaguet, Alain-Arthur; Knoops, S; Lebrun, P; Pezzetti, M; Pirotte, O; Bret, J L; Chabaud, B; Garde, G; Guttin, C; Hébral, B; Pietropinto, S; Roche, P; Barbier-Neyret, J P; Baudet, C; Gagne, Y; Poulain, C; Castaing, B; Ladam, Y; Vittoz, F

    2002-01-01

    The potential of cryogenic helium flows for studying high-Reynolds number turbulence in the laboratory has been recognised for a long time and implemented in several small-scale hydrodynamic experiments. With its large superconducting particle accelerators and detector magnets, CERN, the European Laboratory for Particle Physics, has become a major world center in helium cryogenics, with several large helium refrigerators having capacities up to 18 kW @ 4.5 K. Combining a small fraction of these resources with the expertise of three laboratories at the forefront of turbulence research, has led to the design, swift implementation, and successful operation of GReC (Grands Reynolds Cryogéniques) a large axisymmetric turbulent-jet experiment. With flow-rates up to 260 g/s of gaseous helium at ~ 5 K and atmospheric pressure, Reynolds numbers up to 107 have been achieved in a 4.6 m high, 1.4 m diameter cryostat. This paper presents the results of the first runs and describes the experimental set-up comprehensively ...

  16. Dynamics of an elastic capsule in moderate Reynolds number Poiseuille flow

    International Nuclear Information System (INIS)

    Shin, Soo Jai; Sung, Hyung Jin

    2012-01-01

    Highlights: ► Dynamics of a capsule in moderate Re Poiseuille flow were explored numerically. ► Capsule tends to tumbling motion for larger membrane elasticity and higher Re flow. ► Capsule undergoes swinging motion for larger size and aspect ratio of the capsule. ► Capsule tends to migrate to a specific lateral equilibrium as Re increases. ► Equilibrium position varies differently around the transition of the dynamic motion. - Abstract: The dynamic motions and lateral equilibrium positions of a two-dimensional elastic capsule in a Poiseuille flow were explored at moderate Reynolds number (10 ⩽ Re ⩽ 100) as a function of the initial lateral position (y 0 ), Re, aspect ratio (ε), size ratio (λ), membrane stretching coefficient (φ) and bending coefficient (γ). The transition between tank-treading (TT) and swinging (SW) to tumbling (TU) motions was observed and the lateral equilibrium positions of the capsules varied according to the conditions. The initial behavior of the elastic capsule was influenced by variation in the initial lateral position (y 0 ), but the equilibrium position and dynamic motion of the capsule were not affected by such variation. The capsules had a stronger tendency toward TU motion at higher values of Re, φ and γ, whereas the capsules underwent TT or SW motion as the values of ε and λ increased. Under moderate Re Poiseuille flows, capsules tended to migrate across streamlines to a specific equilibrium position. The lateral equilibrium position shifted toward the centerline at larger λ and migrated toward the wall at larger ε,φandγ. As Re increased, the equilibrium position first shifted toward the bottom wall, then toward the channel center. However, different equilibrium position trends were obtained around the SW–TU transition. The capsule undergoing TU motion tended to migrate downward toward the bottom wall more than the capsule undergoing SW motion, all other conditions being similar.

  17. Experimental Investigation of Turbulence-Chemistry Interaction in High-Reynolds-Number Turbulent Partially Premixed Flames

    Science.gov (United States)

    2016-06-23

    AFRL-AFOSR-VA-TR-2016-0277 Experimental Investigation of Turbulence-Chemistry Interaction in High- Reynolds -Number Turbulent Partially Premixed...4. TITLE AND SUBTITLE [U] Experimental investigation of turbulence-chemistry interaction in high- Reynolds -number 5a. CONTRACT NUMBER turbulent...for public release Final Report: Experimental investigation of turbulence-chemistry interaction in high- Reynolds -number turbulent partially premixed

  18. Bubble Dynamics and Breakup in a T-junction at Moderate Reynolds Numbers

    Science.gov (United States)

    Obiols, Octavi; Rangel, Roger

    2017-11-01

    The deformation and breakup of droplets and bubbles in an immiscible carrier liquid in microchannels has been extensively investigated in the literature. In this study, we address the case of bubbles and drops in a centimeter-scale T-junction at moderate Reynolds numbers, a problem that is relevant for fluidics and emulsion processing applications. The main features include complex oscillating transients, recirculation stabilization, and drop stabilization against breakup. In particular, very elongated drop shapes are observed, which would be unstable in the unbounded case and can be explained in terms of wall-induced distortion of the flow field. We show that wall effects can be exploited to obtain nearly monodisperse emulsions in confined flows. Surface tension also plays an important role on the breakup of the dispersed phase. Different drop sizes can be obtained depending on the Capillary number as well as the bubble initial size. A mechanism for finding the non-breakup and break-up regions depending on bubble size is found. It is found with different initial flow rates of the matrix flow, the non-breakup regime allows for the bubble to remain attached to the bottom wall of the T-junction. In the breakup regime, the elongation of the drop results in a significant delay for breakup, allowing for the study of the breakup time and location. Results are presented for different Ca and Re numbers.

  19. Computation of high Reynolds number internal/external flows

    Science.gov (United States)

    Cline, M. C.; Wilmoth, R. G.

    1981-01-01

    A general, user oriented computer program, called VNAP2, was developed to calculate high Reynolds number, internal/ external flows. The VNAP2 program solves the two dimensional, time dependent Navier-Stokes equations. The turbulence is modeled with either a mixing-length, a one transport equation, or a two transport equation model. Interior grid points are computed using the explicit MacCormack Scheme with special procedures to speed up the calculation in the fine grid. All boundary conditions are calculated using a reference plane characteristic scheme with the viscous terms treated as source terms. Several internal, external, and internal/external flow calculations are presented.

  20. Computation of high Reynolds number internal/external flows

    International Nuclear Information System (INIS)

    Cline, M.C.; Wilmoth, R.G.

    1981-01-01

    A general, user oriented computer program, called VNAP2, has been developed to calculate high Reynolds number, internal/external flows. VNAP2 solves the two-dimensional, time-dependent Navier-Stokes equations. The turbulence is modeled with either a mixing-length, a one transport equation, or a two transport equation model. Interior grid points are computed using the explicit MacCormack scheme with special procedures to speed up the calculation in the fine grid. All boundary conditions are calculated using a reference plane characteristic scheme with the viscous terms treated as source terms. Several internal, external, and internal/external flow calculations are presented

  1. Crossover from High to Low Reynolds Number Turbulence

    NARCIS (Netherlands)

    Lohse, Detlef

    1994-01-01

    The Taylor-Reynolds and Reynolds number (Re lambda and Re) dependence of the dimensionless energy dissipation rate c epsilon = epsilon L / u31,rms is derived for statistically stationary isotropic turbulence, employing the results of a variable range mean field theory. Here epsilon is the energy

  2. Numerical Study of Mixed Convective Peristaltic Flow through Vertical Tube with Heat Generation for Moderate Reynolds and Wave Numbers

    Science.gov (United States)

    Javed, Tariq; Ahmed, B.; Sajid, M.

    2018-04-01

    The current study focuses on the numerical investigation of the mixed convective peristaltic mechanism through a vertical tube for non-zero Reynolds and wave number. In the set of constitutional equations, energy equation contains the term representing heat generation parameter. The problem is formulated by dropping the assumption of lubrication theory that turns the model mathematically into a system of the nonlinear partial differential equations. The results of the long wavelength in a creeping flow are deduced from the present analysis. Thus, the current study explores the neglected features of peristaltic heat flow in the mixed convective model by considering moderate values of Reynolds and wave numbers. The finite element based on Galerkin’s weighted residual scheme is applied to solve the governing equations. The computed solution is presented in the form of contours of streamlines and isothermal lines, velocity and temperature profiles for variation of different involved parameters. The investigation shows that the strength of circulation for stream function increases by increasing the wave number and Reynolds number. Symmetric isotherms are reported for small values of time-mean flow. Linear behavior of pressure is noticed by vanishing inertial forces while the increase in pressure is observed by amplifying the Reynolds number.

  3. High-Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids

    Science.gov (United States)

    2016-05-05

    AFRL-AFOSR-VA-TR-2016-0192 High- Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids Marsha Berger NEW YORK UNIVERSITY Final...TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY) 30/04/2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) High- Reynolds 4. TITLE AND...SUBTITLE High- Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1

  4. High efficiency positron moderation

    International Nuclear Information System (INIS)

    Taqqu, D.

    1990-01-01

    A new positron moderation scheme is proposed. It makes use of electric and magnetic fields to confine the β + emitted by a radioactive source forcing them to slow down within a thin foil. A specific arrangement is described where an intermediary slowed-down beam of energy below 10 keV is produced. By directing it towards a standard moderator optimal conversion into slow positrons is achieved. This scheme is best applied to short lived β + emitters for which a 25% moderation efficiency can be reached. Within the state of the art technology a slow positron source intensity exceeding 2 x 10 10 e + /sec is achievable. (orig.)

  5. Vortex Shedding from Tapered Cylinders at high Reynolds Numbers

    DEFF Research Database (Denmark)

    Johansson, Jens; Andersen, Michael Styrk; Christensen, Silas Sverre

    2015-01-01

    percent for strakes of circular cross section. The present paper argues that this height can be reduced for structures where the critical wind velocity for vortex shedding is in the Supercritical Reynolds number regime. The present investigations are aimed for suppressing VIV on offshore wind turbine......^5 (Supercritical). Results indicate that circular strakes with a diameter corresponding to 3 percent of the structures mean diameter can be used to efficiently reduce VIV in the Supercritical Reynolds number regime....

  6. Irrecoverable pressure loss coefficients for two out-of-plane piping elbows at high Reynolds number

    Energy Technology Data Exchange (ETDEWEB)

    Coffield, R.D.; Hammond, R.B.; McKeown, P.T.

    1999-02-08

    Pressure drops of multiple piping elbows were experimentally determined for high Reynolds number flows. The testing described has been performed in order to reduce uncertainties in the currently used methods for predicting irrecoverable pressure losses and also to provide a qualification database for computational fluid dynamics (CFD) computer codes. The earlier high Reynolds number correlations had been based on extrapolations over several orders of magnitude in Reynolds number from where the original database existed. Recent single elbow test data shows about a factor of two lower elbow pressure loss coefficient (at 40x 106 Reynolds number) than those from current correlations. This single piping elbow data has been extended in this study to a multiple elbow configuration of two elbows that are 90o out-of-plane relative to each other. The effects of separation distance and Reynolds number have been correlated and presented in a form that can be used for design application. Contrary to earlier extrapolations from low Reynolds numbers (Re c 1.0x 106), a strong Reynolds number dependence was found to exist. The combination of the high Reynolds number single elbow data with the multiple elbow interaction effects measured in this study shows that earlier design correlations are conservative by significant margins at high Reynolds numbers. Qualification of CFD predictions with this new high Reynolds number database will help guide the need for additional high Reynolds number testing of other piping configurations. The study also included velocity measurements at several positions downstream of the first and second test elbows using an ultrasonic flowmeter. Reasonable agreement after the first test elbow was found relative to flow fields that are known to exist from low Reynolds number visual tests and also from CFD predictions. This data should help to qualify CFD predictions of the three-dimensional flow stream downstream of the second test elbow.

  7. Perturbed Partial Cavity Drag Reduction at High Reynolds Numbers

    Science.gov (United States)

    Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

    2010-11-01

    Ventilated partial cavities were investigated at Reynolds numbers to 80 million. These cavities could be suitable for friction drag reduction on ocean going vessels and thereby lead to environmental and economical benefits. The test model was a 3.05 m wide by 12.9 m long flat plate, with a 0.18 m backward-facing step and a cavity-terminating beach, which had an adjustable slope, tilt and height. The step and beach trapped a ventilated partial cavity over the longitudinal mid-section of the model. Large-scale flow perturbations, mimicking the effect of ambient ocean waves were investigated. For the conditions tested a cavity could be maintained under perturbed flow conditions when the gas flux supplied was greater than the minimum required to maintain a cavity under steady conditions, with larger perturbations requiring more excess gas flux to maintain the cavity. High-speed video was used to observe the unsteady three dimensional cavity closure, the overall cavity shape, and the cavity oscillations. Cavities with friction drag reduction exceeding 95% were attained at optimal conditions. A simplified energy cost-benefit analysis of partial cavity drag reduction was also performed. The results suggest that PCDR could potentially lead to energy savings.

  8. High-fidelity simulations of moving and flexible airfoils at low Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Visbal, Miguel R.; Gordnier, Raymond E.; Galbraith, Marshall C. [Air Force Research Laboratory, Computational Sciences Branch, Air Vehicles Directorate, Wright-Patterson AFB, OH (United States)

    2009-05-15

    The present paper highlights results derived from the application of a high-fidelity simulation technique to the analysis of low-Reynolds-number transitional flows over moving and flexible canonical configurations motivated by small natural and man-made flyers. This effort addresses three separate fluid dynamic phenomena relevant to small fliers, including: laminar separation and transition over a stationary airfoil, transition effects on the dynamic stall vortex generated by a plunging airfoil, and the effect of flexibility on the flow structure above a membrane airfoil. The specific cases were also selected to permit comparison with available experimental measurements. First, the process of transition on a stationary SD7003 airfoil section over a range of Reynolds numbers and angles of attack is considered. Prior to stall, the flow exhibits a separated shear layer which rolls up into spanwise vortices. These vortices subsequently undergo spanwise instabilities, and ultimately breakdown into fine-scale turbulent structures as the boundary layer reattaches to the airfoil surface. In a time-averaged sense, the flow displays a closed laminar separation bubble which moves upstream and contracts in size with increasing angle of attack for a fixed Reynolds number. For a fixed angle of attack, as the Reynolds number decreases, the laminar separation bubble grows in vertical extent producing a significant increase in drag. For the lowest Reynolds number considered (Re{sub c} = 10 {sup 4}), transition does not occur over the airfoil at moderate angles of attack prior to stall. Next, the impact of a prescribed high-frequency small-amplitude plunging motion on the transitional flow over the SD7003 airfoil is investigated. The motion-induced high angle of attack results in unsteady separation in the leading edge and in the formation of dynamic-stall-like vortices which convect downstream close to the airfoil. At the lowest value of Reynolds number (Re{sub c}=10 {sup 4

  9. Wall modeled large eddy simulations of complex high Reynolds number flows with synthetic inlet turbulence

    International Nuclear Information System (INIS)

    Patil, Sunil; Tafti, Danesh

    2012-01-01

    Highlights: ► Large eddy simulation. ► Wall layer modeling. ► Synthetic inlet turbulence. ► Swirl flows. - Abstract: Large eddy simulations of complex high Reynolds number flows are carried out with the near wall region being modeled with a zonal two layer model. A novel formulation for solving the turbulent boundary layer equation for the effective tangential velocity in a generalized co-ordinate system is presented and applied in the near wall zonal treatment. This formulation reduces the computational time in the inner layer significantly compared to the conventional two layer formulations present in the literature and is most suitable for complex geometries involving body fitted structured and unstructured meshes. The cost effectiveness and accuracy of the proposed wall model, used with the synthetic eddy method (SEM) to generate inlet turbulence, is investigated in turbulent channel flow, flow over a backward facing step, and confined swirling flows at moderately high Reynolds numbers. Predictions are compared with available DNS, experimental LDV data, as well as wall resolved LES. In all cases, there is at least an order of magnitude reduction in computational cost with no significant loss in prediction accuracy.

  10. Hybrid RANS/LES method for high Reynolds numbers, applied to atmospheric flow over complex terrain

    DEFF Research Database (Denmark)

    Bechmann, Andreas; Sørensen, Niels N.; Johansen, Jeppe

    2007-01-01

      The use of Large-Eddy Simulation (LES) to predict wall-bounded flows has presently been limited to low Reynolds number flows. Since the number of computational grid points required to resolve the near-wall turbulent structures increase rapidly with Reynolds number, LES has been unattainable...... for flows at high Reynolds numbers. To reduce the computational cost of traditional LES a hybrid method is proposed in which the near-wall eddies are modelled in a Reynolds-averaged sense. Close to walls the flow is treated with the RANS-equations and this layer act as wall model for the outer flow handled...... by LES. The wellknown high Reynolds number two-equation k - ǫ turbulence model is used in the RANS layer and the model automatically switches to a two-equation k - ǫ subgrid-scale stress model in the LES region. The approach can be used for flow over rough walls. To demonstrate the ability...

  11. Shear-induced autorotation of freely rotatable cylinder in a channel flow at moderate Reynolds number

    Science.gov (United States)

    Xia, Yi; Lin, Jianzhong; Ku, Xiaoke; Chan, Tatleung

    2018-04-01

    Flow past a center-pinned freely rotatable cylinder asymmetrically confined in a two-dimensional channel is simulated with the lattice Boltzmann method for a range of Reynolds number 0.1 ≤ Re ≤ 200, eccentricity ratio 0/8 ≤ ɛ ≤ 7/8, and blockage ratio 0.1 ≤ β ≤ 0.5. It is found that the inertia tends to facilitate the anomalous clockwise rotation of the cylinder. As the eccentricity ratio increases, the cylinder rotates faster in the counterclockwise direction and then slows down at a range of Re 40, there exists an anomalous clockwise rotation for the cylinder at a low eccentricity ratio and the domain where the cylinder rotates anomalously becomes larger with the increase in the Reynolds number. In a channel with a higher blockage ratio, the rotation of the cylinder is more sensitive to the change of cylinder lateral position, and the separatrix at which the cylinder remains a state of rest moves upward generally. The cylinder is more likely to rotate counterclockwise and the rotating velocity is larger. At a lower blockage ratio, the anomalous clockwise rotation is more likely to occur, and the largest rotating velocity occurs when the blockage ratio is equal to 0.3. The mechanism of distinct rotational behavior of the cylinder is attributed to the transformation of distribution of shear stress which is resulted from the variation of pressure drop, the shift of maximum or minimum pressure zones along the upper and lower semi-cylinder surface, and the movement of stagnant point and separate point. Finally, the effects of the cylinder rotation on the flow structure and hydrodynamic force exerted on the cylinder surface are analyzed as well.

  12. Simulations of three-dimensional viscoelastic flows past a circular cylinder at moderate Reynolds numbers

    KAUST Repository

    RICHTER, DAVID

    2010-03-29

    The results from a numerical investigation of inertial viscoelastic flow past a circular cylinder are presented which illustrate the significant effect that dilute concentrations of polymer additives have on complex flows. In particular, effects of polymer extensibility are studied as well as the role of viscoelasticity during three-dimensional cylinder wake transition. Simulations at two distinct Reynolds numbers (Re = 100 and Re = 300) revealed dramatic differences based on the choice of the polymer extensibility (L2 in the FENE-P model), as well as a stabilizing tendency of viscoelasticity. For the Re = 100 case, attention was focused on the effects of increasing polymer extensibility, which included a lengthening of the recirculation region immediately behind the cylinder and a sharp increase in average drag when compared to both the low extensibility and Newtonian cases. For Re = 300, a suppression of the three-dimensional Newtonian mode B instability was observed. This effect is more pronounced for higher polymer extensibilities where all three-dimensional structure is eliminated, and mechanisms for this stabilization are described in the context of roll-up instability inhibition in a viscoelastic shear layer. © 2010 Cambridge University Press.

  13. Design of a High-Reynolds Number Recirculating Water Tunnel

    Science.gov (United States)

    Daniel, Libin; Elbing, Brian

    2014-11-01

    An experimental fluid mechanics laboratory focused on turbulent boundary layers, drag reduction techniques, multiphase flows and fluid-structure interactions has recently been established at Oklahoma State University. This laboratory has three primary components; (1) a recirculating water tunnel, (2) a multiphase pipe flow loop, and (3) a multi-scale flow visualization system. The design of the water tunnel is the focus of this talk. The criteria used for the water tunnel design was that it had to produce a momentum-thickness based Reynolds number in excess of 104, negligible flow acceleration due to boundary layer growth, maximize optical access for use of the flow visualization system, and minimize inlet flow non-uniformity. This Reynolds number was targeted to bridge the gap between typical university/commercial water tunnels (103) and the world's largest water tunnel facilities (105) . These objectives were achieved with a 152 mm (6-inch) square test section that is 1 m long and has a maximum flow speed of 10 m/s. The flow non-uniformity was mitigated with the use of a tandem honeycomb configuration, a settling chamber and an 8.5:1 contraction. The design process that produced this final design will be presented along with its current status.

  14. On the motion of non-spherical particles at high Reynolds number

    DEFF Research Database (Denmark)

    Mandø, Matthias; Rosendahl, Lasse

    2010-01-01

    This paper contains a critical review of available methodology for dealing with the motion of non-spherical particles at higher Reynolds numbers in the Eulerian- Lagrangian methodology for dispersed flow. First, an account of the various attempts to classify the various shapes and the efforts...... motion it is necessary to account for the non-coincidence between the center of pressure and center of gravity which is a direct consequence of the inertial pressure forces associated with particles at high Reynolds number flow. Extensions for non-spherical particles at higher Reynolds numbers are far...

  15. Effects of viscoelasticity in the high Reynolds number cylinder wake

    KAUST Repository

    Richter, David

    2012-01-16

    At Re = 3900, Newtonian flow past a circular cylinder exhibits a wake and detached shear layers which have transitioned to turbulence. It is the goal of the present study to investigate the effects which viscoelasticity has on this state and to identify the mechanisms responsible for wake stabilization. It is found through numerical simulations (employing the FENE-P rheological model) that viscoelasticity greatly reduces the amount of turbulence in the wake, reverting it back to a state which qualitatively appears similar to the Newtonian mode B instability which occurs at lower Re. By focusing on the separated shear layers, it is found that viscoelasticity suppresses the formation of the Kelvin-Helmholtz instability which dominates for Newtonian flows, consistent with previous studies of viscoelastic free shear layers. Through this shear layer stabilization, the viscoelastic far wake is then subject to the same instability mechanisms which dominate for Newtonian flows, but at far lower Reynolds numbers. © Copyright Cambridge University Press 2012.

  16. Numerical simulation of high Reynolds number bubble motion

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, J.B. [Clarkson Univ., Potsdam, NY (United States)

    1995-12-31

    This paper presents the results of numerical simulations of bubble motion. All the results are for single bubbles in unbounded fluids. The liquid phase is quiescent except for the motion created by the bubble, which is axisymmetric. The main focus of the paper is on bubbles that are of order 1 mm in diameter in water. Of particular interest is the effect of surfactant molecules on bubble motion. Results for the {open_quotes}insoluble surfactant{close_quotes} model will be presented. These results extend research by other investigators to finite Reynolds numbers. The results indicate that, by assuming complete coverage of the bubble surface, one obtains good agreement with experimental observations of bubble motion in tap water. The effect of surfactant concentration on the separation angle is discussed.

  17. Effects of viscoelasticity in the high Reynolds number cylinder wake

    KAUST Repository

    Richter, David; Iaccarino, Gianluca; Shaqfeh, Eric S. G.

    2012-01-01

    At Re = 3900, Newtonian flow past a circular cylinder exhibits a wake and detached shear layers which have transitioned to turbulence. It is the goal of the present study to investigate the effects which viscoelasticity has on this state and to identify the mechanisms responsible for wake stabilization. It is found through numerical simulations (employing the FENE-P rheological model) that viscoelasticity greatly reduces the amount of turbulence in the wake, reverting it back to a state which qualitatively appears similar to the Newtonian mode B instability which occurs at lower Re. By focusing on the separated shear layers, it is found that viscoelasticity suppresses the formation of the Kelvin-Helmholtz instability which dominates for Newtonian flows, consistent with previous studies of viscoelastic free shear layers. Through this shear layer stabilization, the viscoelastic far wake is then subject to the same instability mechanisms which dominate for Newtonian flows, but at far lower Reynolds numbers. © Copyright Cambridge University Press 2012.

  18. Prospectus: towards the development of high-fidelity models of wall turbulence at large Reynolds number.

    Science.gov (United States)

    Klewicki, J C; Chini, G P; Gibson, J F

    2017-03-13

    Recent and on-going advances in mathematical methods and analysis techniques, coupled with the experimental and computational capacity to capture detailed flow structure at increasingly large Reynolds numbers, afford an unprecedented opportunity to develop realistic models of high Reynolds number turbulent wall-flow dynamics. A distinctive attribute of this new generation of models is their grounding in the Navier-Stokes equations. By adhering to this challenging constraint, high-fidelity models ultimately can be developed that not only predict flow properties at high Reynolds numbers, but that possess a mathematical structure that faithfully captures the underlying flow physics. These first-principles models are needed, for example, to reliably manipulate flow behaviours at extreme Reynolds numbers. This theme issue of Philosophical Transactions of the Royal Society A provides a selection of contributions from the community of researchers who are working towards the development of such models. Broadly speaking, the research topics represented herein report on dynamical structure, mechanisms and transport; scale interactions and self-similarity; model reductions that restrict nonlinear interactions; and modern asymptotic theories. In this prospectus, the challenges associated with modelling turbulent wall-flows at large Reynolds numbers are briefly outlined, and the connections between the contributing papers are highlighted.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

  19. Prospectus: towards the development of high-fidelity models of wall turbulence at large Reynolds number

    Science.gov (United States)

    Klewicki, J. C.; Chini, G. P.; Gibson, J. F.

    2017-01-01

    Recent and on-going advances in mathematical methods and analysis techniques, coupled with the experimental and computational capacity to capture detailed flow structure at increasingly large Reynolds numbers, afford an unprecedented opportunity to develop realistic models of high Reynolds number turbulent wall-flow dynamics. A distinctive attribute of this new generation of models is their grounding in the Navier–Stokes equations. By adhering to this challenging constraint, high-fidelity models ultimately can be developed that not only predict flow properties at high Reynolds numbers, but that possess a mathematical structure that faithfully captures the underlying flow physics. These first-principles models are needed, for example, to reliably manipulate flow behaviours at extreme Reynolds numbers. This theme issue of Philosophical Transactions of the Royal Society A provides a selection of contributions from the community of researchers who are working towards the development of such models. Broadly speaking, the research topics represented herein report on dynamical structure, mechanisms and transport; scale interactions and self-similarity; model reductions that restrict nonlinear interactions; and modern asymptotic theories. In this prospectus, the challenges associated with modelling turbulent wall-flows at large Reynolds numbers are briefly outlined, and the connections between the contributing papers are highlighted. This article is part of the themed issue ‘Toward the development of high-fidelity models of wall turbulence at large Reynolds number’. PMID:28167585

  20. Numerical analysis of jet impingement heat transfer at high jet Reynolds number and large temperature difference

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2013-01-01

    was investigated at a jet Reynolds number of 1.66 × 105 and a temperature difference between jet inlet and wall of 1600 K. The focus was on the convective heat transfer contribution as thermal radiation was not included in the investigation. A considerable influence of the turbulence intensity at the jet inlet...... to about 100% were observed. Furthermore, the variation in stagnation point heat transfer was examined for jet Reynolds numbers in the range from 1.10 × 105 to 6.64 × 105. Based on the investigations, a correlation is suggested between the stagnation point Nusselt number, the jet Reynolds number......, and the turbulence intensity at the jet inlet for impinging jet flows at high jet Reynolds numbers. Copyright © 2013 Taylor and Francis Group, LLC....

  1. Qualification of a Method to Calculate the Irrecoverable Pressure Loss in High Reynolds Number Piping Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sigg, K. C.; Coffield, R. D.

    2002-09-01

    High Reynolds number test data has recently been reported for both single and multiple piping elbow design configurations at earlier ASME Fluid Engineering Division conferences. The data of these studies ranged up to a Reynolds number of 42 x 10[sup]6 which is significantly greater than that used to establish design correlations before the data was available. Many of the accepted design correlations, based on the lower Reynolds number data, date back as much as fifty years. The new data shows that these earlier correlations are extremely conservative for high Reynolds number applications. Based on the recent high Reynolds number information a new recommended method has been developed for calculating irrecoverable pressure loses in piping systems for design considerations such as establishing pump sizing requirements. This paper describes the recommended design approach and additional testing that has been performed as part of the qualification of the method. This qualification testing determined the irrecoverable pressure loss of a piping configuration that would typify a limiting piping section in a complicated piping network, i.e., multiple, tightly coupled, out-of-plane elbows in series under high Reynolds number flow conditions. The overall pressure loss measurements were then compared to predictions, which used the new methodology to assure that conservative estimates for the pressure loss (of the type used for pump sizing) were obtained. The recommended design methodology, the qualification testing and the comparison between the predictions and the test data are presented. A major conclusion of this study is that the recommended method for calculating irrecoverable pressure loss in piping systems is conservative yet significantly lower than predicted by early design correlations that were based on the extrapolation of low Reynolds number test data.

  2. Application of a Full Reynolds Stress Model to High Lift Flows

    Science.gov (United States)

    Lee-Rausch, E. M.; Rumsey, C. L.; Eisfeld, B.

    2016-01-01

    A recently developed second-moment Reynolds stress model was applied to two challenging high-lift flows: (1) transonic flow over the ONERA M6 wing, and (2) subsonic flow over the DLR-F11 wing-body configuration from the second AIAA High Lift Prediction Workshop. In this study, the Reynolds stress model results were contrasted with those obtained from one- and two{equation turbulence models, and were found to be competitive in terms of the prediction of shock location and separation. For an ONERA M6 case, results from multiple codes, grids, and models were compared, with the Reynolds stress model tending to yield a slightly smaller shock-induced separation bubble near the wing tip than the simpler models, but all models were fairly close to the limited experimental surface pressure data. For a series of high-lift DLR{F11 cases, the range of results was more limited, but there was indication that the Reynolds stress model yielded less-separated results than the one-equation model near maximum lift. These less-separated results were similar to results from the one-equation model with a quadratic constitutive relation. Additional computations need to be performed before a more definitive assessment of the Reynolds stress model can be made.

  3. Numerical investigation of the high Reynolds number 3D flow field generated by a self-propelling manta ray

    Science.gov (United States)

    Pederzani, Jean-Noel; Haj-Hariri, Hossein

    2012-11-01

    An embedded-boundary (or cut-cell) method for complex geometry with moving boundaries is used to solve the three dimensional Navier-Stokes equation around a self-propelling manta swimming at moderately high Reynolds numbers. The motion of the ray is prescribed using a kinematic model fitted to actual biological data. The dependence of thrust production mechanism on Strouhal and Reynolds numbers is investigated. The vortex core structures are accurately plotted and a correlation between wake structures and propulsive performance is established. This insight is critical in understanding the key flow features that a bio-inspired autonomous vehicle should reproduce in order to swim efficiently. The solution method is implemented, on a block-structured Cartesian grid using a cut-cell approach enabling the code to correctly evaluate the wall shear-stress, a key feature necessary at higher Reynolds. To enhance computational efficiency, a parallel adaptive mesh refinement technique is used. The present method is validated against published experimental results. Supported by ONR MURI.

  4. Advanced lattice Boltzmann scheme for high-Reynolds-number magneto-hydrodynamic flows

    Science.gov (United States)

    De Rosis, Alessandro; Lévêque, Emmanuel; Chahine, Robert

    2018-06-01

    Is the lattice Boltzmann method suitable to investigate numerically high-Reynolds-number magneto-hydrodynamic (MHD) flows? It is shown that a standard approach based on the Bhatnagar-Gross-Krook (BGK) collision operator rapidly yields unstable simulations as the Reynolds number increases. In order to circumvent this limitation, it is here suggested to address the collision procedure in the space of central moments for the fluid dynamics. Therefore, an hybrid lattice Boltzmann scheme is introduced, which couples a central-moment scheme for the velocity with a BGK scheme for the space-and-time evolution of the magnetic field. This method outperforms the standard approach in terms of stability, allowing us to simulate high-Reynolds-number MHD flows with non-unitary Prandtl number while maintaining accuracy and physical consistency.

  5. A comparative study of near-wall turbulence in high and low Reynolds number boundary layers

    International Nuclear Information System (INIS)

    Metzger, M.M.; Klewicki, J.C.

    2001-01-01

    The present study explores the effects of Reynolds number, over three orders of magnitude, in the viscous wall region of a turbulent boundary layer. Complementary experiments were conducted both in the boundary layer wind tunnel at the University of Utah and in the atmospheric surface layer which flows over the salt flats of the Great Salt Lake Desert in western Utah. The Reynolds numbers, based on momentum deficit thickness, of the two flows were R θ =2x10 3 and R θ ≅5x10 6 , respectively. High-resolution velocity measurements were obtained from a five-element vertical rake of hot-wires spanning the buffer region. In both the low and high R θ flows, the length of the hot-wires measured less than 6 viscous units. To facilitate reliable comparisons, both the laboratory and field experiments employed the same instrumentation and procedures. Data indicate that, even in the immediate vicinity of the surface, strong influences from low-frequency motions at high R θ produce noticeable Reynolds number differences in the streamwise velocity and velocity gradient statistics. In particular, the peak value in the root mean square streamwise velocity profile, when normalized by viscous scales, was found to exhibit a logarithmic dependence on Reynolds number. The mean streamwise velocity profile, on the other hand, appears to be essentially independent of Reynolds number. Spectra and spatial correlation data suggest that low-frequency motions at high Reynolds number engender intensified local convection velocities which affect the structure of both the velocity and velocity gradient fields. Implications for turbulent production mechanisms and coherent motions in the buffer layer are discussed

  6. Multigrid solution of the convection-diffusion equation with high-Reynolds number

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [George Washington Univ., Washington, DC (United States)

    1996-12-31

    A fourth-order compact finite difference scheme is employed with the multigrid technique to solve the variable coefficient convection-diffusion equation with high-Reynolds number. Scaled inter-grid transfer operators and potential on vectorization and parallelization are discussed. The high-order multigrid method is unconditionally stable and produces solution of 4th-order accuracy. Numerical experiments are included.

  7. Magnus effects at high angles of attack and critical Reynolds numbers

    Science.gov (United States)

    Seginer, A.; Ringel, M.

    1983-01-01

    The Magnus force and moment experienced by a yawed, spinning cylinder were studied experimentally in low speed and subsonic flows at high angles of attack and critical Reynolds numbers. Flow-field visualization aided in describing a flow model that divides the Magnus phenomenon into a subcritical region, where reverse Magnus loads are experienced, and a supercritical region where these loads are not encountered. The roles of the spin rate, angle of attack, and crossflow Reynolds number in determining the boundaries of the subcritical region and the variations of the Magnus loads were studied.

  8. Numerical simulations of flows through fixed networks of monodispersed and bi-dispersed spheres, for moderate Reynolds numbers; Simulations numeriques d'ecoulements a travers des reseaux fixes de spheres monodisperses et bidisperses, pour des nombres de Reynolds moderes

    Energy Technology Data Exchange (ETDEWEB)

    Massol, A.

    2004-02-15

    The application of statistically averaged two-fluid models for the simulation of complex indus- trial two-phase flows requires the development of adequate models for the drag force exerted on the inclusions and the interfacial heat exchange. This task becomes problematic at high volume fractions of the dispersed phase. The quality of the simulation strongly depends upon the inter- facial exchange terms, starting with the steady drag force. For example, an accurate modelling of the drag force is therefore a crucial point to simulate the expansion of dense fluidized beds. Most models used to study the exchange terms between particles and fluids are based on the interaction between an isolated particle and a surrounding gas. Those models are clearly not adequate in cases where the volume fraction of particles increases and particle-particle interactions become important. Studying such cases is a complex task because of the multiple possible configurations. While the interaction between an isolated sphere and a gas depends only on the particle size and the slip velocity between gas and particles, the interaction between a cloud of particles and a gas depends on many more parameters: size and velocity distribution of particles, relative position of particles. Even if the particles keep relative fixed positions, there is an infinite number of combinations to construct such an array. The objective of the present work is to perform steady and unsteady simulations of the flow in regular arrays of fixed particles in order to analyze the influence of the size and distributions of spheres on drag force and heat transfer (the array of spheres can be either monodispersed, either bi-dispersed). Several authors have studied the drag exerted on the spheres, but only for low Reynolds numbers and/or solid volume fractions close to the packed limit. Moreover some discrepancies are observed between the different studies. On top of that, all existing studies are limited to steady flows

  9. Mass transfer in wetted-wall columns: correlations at high Reynolds numbers

    DEFF Research Database (Denmark)

    Nielsen, Christian H.E.; Kiil, Søren; Thomsen, Henrik W.

    1998-01-01

    (G)) were determined. In dimensionless form, the correlations are given by Sh(L) = 0.01613 Re-G(0.664) Re-L(0.426) Sc-L(0.5) Sh(G) = 0.00031 Re-G(1.05) Re-L(0.207) Sc-G(0.5) and are valid at gas-phase Reynolds numbers from 7500 to 18,300 and liquid-phase Reynolds numbers from 4000 to 12,000, conditions...... of industrial relevance. To our knowledge, no correlations for Sh(G) have been reported in the literature which are valid at such high Reynolds numbers. The wetted-wall column was equipped with six intermediate measuring positions for gas and two for liquid samples, giving rise to a high accuracy...... of the obtained correlations. Our data showed that Sh(L) and Sh(G) both depend on Re-G and Re-L due to changes in the interfacial area at the high Reynolds numbers employed. The presence of inert particles in the liquid-phase may influence the rate of mass transport, and experimental work was initiated to study...

  10. Normalizations of High Taylor Reynolds Number Power Spectra

    Science.gov (United States)

    Puga, Alejandro; Koster, Timothy; Larue, John C.

    2014-11-01

    The velocity power spectrum provides insight in how the turbulent kinetic energy is transferred from larger to smaller scales. Wind tunnel experiments are conducted where high intensity turbulence is generated by means of an active turbulence grid modeled after Makita's 1991 design (Makita, 1991) as implemented by Mydlarski and Warhaft (M&W, 1998). The goal of this study is to document the evolution of the scaling region and assess the relative collapse of several proposed normalizations over a range of Rλ from 185 to 997. As predicted by Kolmogorov (1963), an asymptotic approach of the slope (n) of the inertial subrange to - 5 / 3 with increasing Rλ is observed. There are three velocity power spectrum normalizations as presented by Kolmogorov (1963), Von Karman and Howarth (1938) and George (1992). Results show that the Von Karman and Howarth normalization does not collapse the velocity power spectrum as well as the Kolmogorov and George normalizations. The Kolmogorov normalization does a good job of collapsing the velocity power spectrum in the normalized high wavenumber range of 0 . 0002 University of California, Irvine Research Fund.

  11. DNS/LES Simulations of Separated Flows at High Reynolds Numbers

    Science.gov (United States)

    Balakumar, P.

    2015-01-01

    Direct numerical simulations (DNS) and large-eddy simulations (LES) simulations of flow through a periodic channel with a constriction are performed using the dynamic Smagorinsky model at two Reynolds numbers of 2800 and 10595. The LES equations are solved using higher order compact schemes. DNS are performed for the lower Reynolds number case using a fine grid and the data are used to validate the LES results obtained with a coarse and a medium size grid. LES simulations are also performed for the higher Reynolds number case using a coarse and a medium size grid. The results are compared with an existing reference data set. The DNS and LES results agreed well with the reference data. Reynolds stresses, sub-grid eddy viscosity, and the budgets for the turbulent kinetic energy are also presented. It is found that the turbulent fluctuations in the normal and spanwise directions have the same magnitude. The turbulent kinetic energy budget shows that the production peaks near the separation point region and the production to dissipation ratio is very high on the order of five in this region. It is also observed that the production is balanced by the advection, diffusion, and dissipation in the shear layer region. The dominant term is the turbulent diffusion that is about two times the molecular dissipation.

  12. Intermittent dynamics of nonlinear resistive tearing modes at extremely high magnetic Reynolds number

    International Nuclear Information System (INIS)

    Miyoshi, Takahiro; Becchaku, Masahiro; Kusano, Kanya

    2008-01-01

    Nonlinear dynamics of the resistive tearing instability in high magnetic Reynolds number (R m ) plasmas is studied by newly developing an accurate and robust resistive magnetohydrodynamic (MHD) scheme. The results show that reconnection processes strongly depend on R m . Particularly, in a high R m case, small-scale plasmoids induced by a secondary instability are intermittently generated and ejected accompanied by fast shocks. According to the intermittent processes, the reconnection rate increases intermittently at a later nonlinear stage. (author)

  13. Active Control of Flow Separation on a High-Lift System with Slotted Flap at High Reynolds Number

    Science.gov (United States)

    Khodadoust, Abdollah; Washburn, Anthony

    2007-01-01

    The NASA Energy Efficient Transport (EET) airfoil was tested at NASA Langley's Low- Turbulence Pressure Tunnel (LTPT) to assess the effectiveness of distributed Active Flow Control (AFC) concepts on a high-lift system at flight scale Reynolds numbers for a medium-sized transport. The test results indicate presence of strong Reynolds number effects on the high-lift system with the AFC operational, implying the importance of flight-scale testing for implementation of such systems during design of future flight vehicles with AFC. This paper describes the wind tunnel test results obtained at the LTPT for the EET high-lift system for various AFC concepts examined on this airfoil.

  14. Further experiments for mean velocity profile of pipe flow at high Reynolds number

    Science.gov (United States)

    Furuichi, N.; Terao, Y.; Wada, Y.; Tsuji, Y.

    2018-05-01

    This paper reports further experimental results obtained in high Reynolds number actual flow facility in Japan. The experiments were performed in a pipe flow with water, and the friction Reynolds number was varied up to Reτ = 5.3 × 104. This high Reynolds number was achieved by using water as the working fluid and adopting a large-diameter pipe (387 mm) while controlling the flow rate and temperature with high accuracy and precision. The streamwise velocity was measured by laser Doppler velocimetry close to the wall, and the mean velocity profile, called log-law profile U+ = (1/κ) ln(y+) + B, is especially focused. After careful verification of the mean velocity profiles in terms of the flow rate accuracy and an evaluation of the consistency of the present results with those from previously measurements in a smaller pipe (100 mm), it was found that the value of κ asymptotically approaches a constant value of κ = 0.384.

  15. On the POD based reduced order modeling of high Reynolds flows

    Science.gov (United States)

    Behzad, Fariduddin; Helenbrook, Brian; Ahmadi, Goodarz

    2012-11-01

    Reduced-order modeling (ROM) of a high Reynolds fluid flow using the proper orthogonal decomposition (POD) was studied. Particular attention was given to incompressible, unsteady flow over a two-dimensional NACA0015 airfoil. The Reynolds number is 105 and the angle of attacked of the airfoil is 12°. For DNS solution, hp-finite element method is employed to drive flow samples from which the POD modes are extracted. Particular attention is paid on two issues. First, the stability of POD-ROM resimulation of the turbulent flow is studied. High Reynolds flow contains a lot of fluctuating modes. So, to reach a certain amount of error, more POD modes are needed and the effect of truncation of POD modes is more important. Second, the role of convergence rate on the results of POD. Due to complexity of the flow, convergence of the governing equations is more difficult and the influences of weak convergence appear in the results of POD-ROM. For each issue, the capability of the POD-ROM is assessed in terms of predictions quality of times upon which the POD model was derived. The results are compared with DNS solution and the accuracy and efficiency of different cases are evaluated.

  16. High-Reynolds Number Circulation Control Testing in the National Transonic Facility

    Science.gov (United States)

    Milholen, William E., II; Jones, Gregory S.; Chan, David T.; Goodliff, Scott L.

    2012-01-01

    A new capability to test active flow control concepts and propulsion simulations at high Reynolds numbers in the National Transonic Facility at the NASA Langley Research Center is being developed. The first active flow control experiment was completed using the new FAST-MAC semi-span model to study Reynolds number scaling effects for several circulation control concepts. Testing was conducted over a wide range of Mach numbers, up to chord Reynolds numbers of 30 million. The model was equipped with four onboard flow control valves allowing independent control of the circulation control plenums, which were directed over a 15% chord simple-hinged flap. Preliminary analysis of the uncorrected lift data showed that the circulation control increased the low-speed maximum lift coefficient by 33%. At transonic speeds, the circulation control was capable of positively altering the shockwave pattern on the upper wing surface and reducing flow separation. Furthermore, application of the technique to only the outboard portion of the wing demonstrated the feasibility of a pneumatic based roll control capability.

  17. Numerical simulation of flow around the NREL S826 airfoil at moderate Reynolds number using delayed detached Eddy simulation (DDES)

    Science.gov (United States)

    Prytz, Erik R.; Huuse, Øyvind; Müller, Bernhard; Bartl, Jan; Sætran, Lars Roar

    2017-07-01

    Turbulent flow at Reynolds numbers 5 . 104 to 106 around the NREL S826 airfoil used for wind turbine blades is simulated using delayed detached eddy simulation (DDES). The 3D domain is built as a replica of the low speed wind tunnel at the Norwegian University of Science and Technology (NTNU) with the wind tunnel walls considered as slip walls. The subgrid turbulent kinetic energy is used to model the sub-grid scale in the large eddy simulation (LES) part of DDES. Different Reynoldsaveraged Navier-Stokes (RANS) models are tested in ANSYS Fluent. The realizable k - ∈ model as the RANS model in DDES is found to yield the best agreement of simulated pressure distributions with the experimental data both from NTNU and the Technical University of Denmark (DTU), the latter for a shorter spanwise domain. The present DDES results are in excellent agreement with LES results from DTU. Since DDES requires much fewer cells in the RANS region near the wing surface than LES, DDES is computationally much more efficient than LES. Whereas DDES is able to predict lift and drag in close agreement with experiment up to stall, pure 2D RANS simulations fail near stall. After testing different numerical settings, time step sizes and grids for DDES, a Reynolds number study is conducted. Near stall, separated flow structures, so-called stall cells, are observed in the DDES results.

  18. Anomalous dissipation and kinetic-energy distribution in pipes at very high Reynolds numbers.

    Science.gov (United States)

    Chen, Xi; Wei, Bo-Bo; Hussain, Fazle; She, Zhen-Su

    2016-01-01

    A symmetry-based theory is developed for the description of (streamwise) kinetic energy K in turbulent pipes at extremely high Reynolds numbers (Re's). The theory assumes a mesolayer with continual deformation of wall-attached eddies which introduce an anomalous dissipation, breaking the exact balance between production and dissipation. An outer peak of K is predicted above a critical Re of 10^{4}, in good agreement with experimental data. The theory offers an alternative explanation for the recently discovered logarithmic distribution of K. The concept of anomalous dissipation is further supported by a significant modification of the k-ω equation, yielding an accurate prediction of the entire K profile.

  19. Experimental investigation of acoustic streaming in a cylindrical wave guide up to high streaming Reynolds numbers.

    Science.gov (United States)

    Reyt, Ida; Bailliet, Hélène; Valière, Jean-Christophe

    2014-01-01

    Measurements of streaming velocity are performed by means of Laser Doppler Velocimetry and Particle Image Velociimetry in an experimental apparatus consisting of a cylindrical waveguide having one loudspeaker at each end for high intensity sound levels. The case of high nonlinear Reynolds number ReNL is particularly investigated. The variation of axial streaming velocity with respect to the axial and to the transverse coordinates are compared to available Rayleigh streaming theory. As expected, the measured streaming velocity agrees well with the Rayleigh streaming theory for small ReNL but deviates significantly from such predictions for high ReNL. When the nonlinear Reynolds number is increased, the outer centerline axial streaming velocity gets distorted towards the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes. This kind of behavior is followed by outer streaming cells only and measurements in the near wall region show that inner streaming vortices are less affected by this substantial evolution of fast streaming pattern. Measurements of the transient evolution of streaming velocity provide an additional insight into the evolution of fast streaming.

  20. NASA High-Reynolds Number Circulation Control Research - Overview of CFD and Planned Experiments

    Science.gov (United States)

    Milholen, W. E., II; Jones, Greg S.; Cagle, Christopher M.

    2010-01-01

    A new capability to test active flow control concepts and propulsion simulations at high Reynolds numbers in the National Transonic Facility at the NASA Langley Research Center is being developed. This technique is focused on the use of semi-span models due to their increased model size and relative ease of routing high-pressure air to the model. A new dual flow-path high-pressure air delivery station has been designed, along with a new high performance transonic sem -si pan wing model. The modular wind tunnel model is designed for testing circulation control concepts at both transonic cruise and low-speed high-lift conditions. The ability of the model to test other active flow control techniques will be highlighted. In addition, a new higher capacity semi-span force and moment wind tunnel balance has been completed and calibrated to enable testing at transonic conditions.

  1. The time scale for the transition to turbulence in a high Reynolds number, accelerated flow

    International Nuclear Information System (INIS)

    Robey, H.F.; Zhou Ye; Buckingham, A.C.; Keiter, P.; Remington, B.A.; Drake, R.P.

    2003-01-01

    An experiment is described in which an interface between materials of different density is subjected to an acceleration history consisting of a strong shock followed by a period of deceleration. The resulting flow at this interface, initiated by the deposition of strong laser radiation into the initially well characterized solid materials, is unstable to both the Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities. These experiments are of importance in their ability to access a difficult experimental regime characterized by very high energy density (high temperature and pressure) as well as large Reynolds number and Mach number. Such conditions are of interest, for example, in the study of the RM/RT induced mixing that occurs during the explosion of a core-collapse supernova. Under these experimental conditions, the flow is in the plasma state and given enough time will transition to turbulence. By analysis of the experimental data and a corresponding one-dimensional numerical simulation of the experiment, it is shown that the Reynolds number is sufficiently large (Re>10 5 ) to support a turbulent flow. An estimate of three key turbulence length scales (the Taylor and Kolmogorov microscales and a viscous diffusion scale), however, shows that the temporal duration of the present flow is insufficient to allow for the development of a turbulent inertial subrange. A methodology is described for estimating the time required under these conditions for the development of a fully turbulent flow

  2. Multi-resolution Delta-plus-SPH with tensile instability control: Towards high Reynolds number flows

    Science.gov (United States)

    Sun, P. N.; Colagrossi, A.; Marrone, S.; Antuono, M.; Zhang, A. M.

    2018-03-01

    It is well known that the use of SPH models in simulating flow at high Reynolds numbers is limited because of the tensile instability inception in the fluid region characterized by high vorticity and negative pressure. In order to overcome this issue, the δ+-SPH scheme is modified by implementing a Tensile Instability Control (TIC). The latter consists of switching the momentum equation to a non-conservative formulation in the unstable flow regions. The loss of conservation properties is shown to induce small errors, provided that the particle distribution is regular. The latter condition can be ensured thanks to the implementation of a Particle Shifting Technique (PST). The novel variant of the δ+-SPH is proved to be effective in preventing the onset of tensile instability. Several challenging benchmark tests involving flows past bodies at large Reynolds numbers have been used. Within this a simulation characterized by a deforming foil that resembles a fish-like swimming body is used as a practical application of the δ+-SPH model in biological fluid mechanics.

  3. A turbulence model for large interfaces in high Reynolds two-phase CFD

    International Nuclear Information System (INIS)

    Coste, P.; Laviéville, J.

    2015-01-01

    Highlights: • Two-phase CFD commonly involves interfaces much larger than the computational cells. • A two-phase turbulence model is developed to better take them into account. • It solves k–epsilon transport equations in each phase. • The special treatments and transfer terms at large interfaces are described. • Validation cases are presented. - Abstract: A model for two-phase (six-equation) CFD modelling of turbulence is presented, for the regions of the flow where the liquid–gas interface takes place on length scales which are much larger than the typical computational cell size. In the other regions of the flow, the liquid or gas volume fractions range from 0 to 1. Heat and mass transfer, compressibility of the fluids, are included in the system, which is used at high Reynolds numbers in large scale industrial calculations. In this context, a model based on k and ε transport equations in each phase was chosen. The paper describes the model, with a focus on the large interfaces, which require special treatments and transfer terms between the phases, including some approaches inspired from wall functions. The validation of the model is based on high Reynolds number experiments with turbulent quantities measurements of a liquid jet impinging a free surface and an air water stratified flow. A steam–water stratified condensing flow experiment is also used for an indirect validation in the case of heat and mass transfer

  4. Reynolds-averaged Navier-Stokes investigation of high-lift low-pressure turbine blade aerodynamics at low Reynolds number

    Science.gov (United States)

    Arko, Bryan M.

    Design trends for the low-pressure turbine (LPT) section of modern gas turbine engines include increasing the loading per airfoil, which promises a decreased airfoil count resulting in reduced manufacturing and operating costs. Accurate Reynolds-Averaged Navier-Stokes predictions of separated boundary layers and transition to turbulence are needed, as the lack of an economical and reliable computational model has contributed to this high-lift concept not reaching its full potential. Presented here for what is believed to be the first time applied to low-Re computations of high-lift linear cascade simulations is the Abe-Kondoh-Nagano (AKN) linear low-Re two-equation turbulence model which utilizes the Kolmogorov velocity scale for improved predictions of separated boundary layers. A second turbulence model investigated is the Kato-Launder modified version of the AKN, denoted MPAKN, which damps turbulent production in highly strained regions of flow. Fully Laminar solutions have also been calculated in an effort to elucidate the transitional quality of the turbulence model solutions. Time accurate simulations of three modern high-lift blades at a Reynolds number of 25,000 are compared to experimental data and higher-order computations in order to judge the accuracy of the results, where it is shown that the RANS simulations with highly refined grids can produce both quantitatively and qualitatively similar separation behavior as found in experiments. In particular, the MPAKN model is shown to predict the correct boundary layer behavior for all three blades, and evidence of transition is found through inspection of the components of the Reynolds Stress Tensor, spectral analysis, and the turbulence production parameter. Unfortunately, definitively stating that transition is occurring becomes an uncertain task, as similar evidence of the transition process is found in the Laminar predictions. This reveals that boundary layer reattachment may be a result of laminar

  5. Nuclear data generation for cryogenic moderators and high temperature moderators

    International Nuclear Information System (INIS)

    Petriw, Sergio

    2007-01-01

    The commonly used processing codes for nuclear data only allow the generation of cross section data for a limited number of materials and physical conditions.At present, one of the most used computer codes for the generation of neutron cross sections is N J O Y, which is based on a phonon expansion of the scattering function starting from the frequency spectrum.Therefore, the information related to the system's density of states is crucial to produce the required data of interest. In this work the formalism of the Synthetic Model for Molecular Solids (S M M S) was implemented, which is in turn based on the Synthetic Frequency Spectrum (S F S) concept.The synthetic spectrum is central in the present work, and it is built from simple, relevant parameters of the moderator, thus conforming an alternative tool when no information on the actual frequency spectrum of the moderator material is available.S F S 's for several material of interest where produced in this work, for both cryogenic and high temperature moderators.We studied some materials of special interest, like solid methane, ice, methyl clathrate and two which are of special interest in the nuclear industry: graphite and beryllium.The libraries generated in the present work for the materials considered, in spite of their synthetic origin, are able to produce results that are even in better agreement with available information [es

  6. The effect of tip speed ratio on a vertical axis wind turbine at high Reynolds numbers

    Science.gov (United States)

    Parker, Colin M.; Leftwich, Megan C.

    2016-05-01

    This work visualizes the flow surrounding a scaled model vertical axis wind turbine at realistic operating conditions. The model closely matches geometric and dynamic properties—tip speed ratio and Reynolds number—of a full-size turbine. The flow is visualized using particle imaging velocimetry (PIV) in the midplane upstream, around, and after (up to 4 turbine diameters downstream) the turbine, as well as a vertical plane behind the turbine. Time-averaged results show an asymmetric wake behind the turbine, regardless of tip speed ratio, with a larger velocity deficit for a higher tip speed ratio. For the higher tip speed ratio, an area of averaged flow reversal is present with a maximum reverse flow of -0.04U_∞. Phase-averaged vorticity fields—achieved by syncing the PIV system with the rotation of the turbine—show distinct structures form from each turbine blade. There were distinct differences in results by tip speed ratios of 0.9, 1.3, and 2.2 of when in the cycle structures are shed into the wake—switching from two pairs to a single pair of vortices being shed—and how they convect into the wake—the middle tip speed ratio vortices convect downstream inside the wake, while the high tip speed ratio pair is shed into the shear layer of the wake. Finally, results show that the wake structure is much more sensitive to changes in tip speed ratio than to changes in Reynolds number.

  7. Trajectory of a synthetic jet issuing into a high Reynolds number turbulent boundary layer

    Science.gov (United States)

    Berk, Tim; Baidya, Rio; de Silva, Charitha; Marusic, Ivan; Hutchins, Nicholas; Ganapathisubramani, Bharathram

    2017-11-01

    Synthetic jets are zero-net-mass-flux actuators that can be used in a range of flow control applications. For several pulsed/synthetic jet in cross-flow applications the variation of the jet trajectory in the mean flow with jet and boundary layer parameters is important. This trajectory will provide an indication of the penetration depth of the pulsed/synthetic jet into a boundary layer. Trajectories of a synthetic jet in a turbulent boundary layer are measured for a range of actuation parameters in both low- and high Reynolds numbers (up to Reτ = 13000). The important parameters influencing the trajectory are determined from these measurements. The Reynolds number of the boundary layer is shown to only have a small effect on the trajectory. In fact, the critical parameters are found to be the Strouhal number of the jet based on jet dimensions as well as the velocity ratio of the jet (defined as a ratio between peak jet velocity and the freestream velocity). An expression for the trajectory of the synthetic (or pulsed) jet is derived from the data, which (in the limit) is consistent with known expressions for the trajectory of a steady jet in a cross-flow. T.B. and B.G. are grateful to the support from the ERC (Grant Agreement No. 277472) and the EPSRC (Grant ref. no. EP/L006383/1).

  8. How do rigid-lid assumption affect LES simulation results at high Reynolds flows?

    Science.gov (United States)

    Khosronejad, Ali; Farhadzadeh, Ali; SBU Collaboration

    2017-11-01

    This research is motivated by the work of Kara et al., JHE, 2015. They employed LES to model flow around a model of abutment at a Re number of 27,000. They showed that first-order turbulence characteristics obtained by rigid-lid (RL) assumption compares fairly well with those of level-set (LS) method. Concerning the second-order statistics, however, their simulation results showed a significant dependence on the method used to describe the free surface. This finding can have important implications for open channel flow modeling. The Reynolds number for typical open channel flows, however, could be much larger than that of Kara et al.'s test case. Herein, we replicate the reported study by augmenting the geometric and hydraulic scales to reach a Re number of one order of magnitude larger ( 200,000). The Virtual Flow Simulator (VFS-Geophysics) model in its LES mode is used to simulate the test case using both RL and LS methods. The computational results are validated using measured flow and free-surface data from our laboratory experiments. Our goal is to investigate the effects of RL assumption on both first-order and second order statistics at high Reynolds numbers that occur in natural waterways. Acknowledgment: Computational resources are provided by the Center of Excellence in Wireless & Information Technology (CEWIT) of Stony Brook University.

  9. Numerical solution of the Navier--Stokes equations at high Reynolds numbers

    International Nuclear Information System (INIS)

    Shestakov, A.I.

    1974-01-01

    A numerical method is presented which is designed to solve the Navier-Stokes equations for two-dimensional, incompressible flow. The method is intended for use on problems with high Reynolds numbers for which calculations via finite difference methods have been unattainable or unreliable. The proposed scheme is a hybrid utilizing a time-splitting finite difference method in areas away from the boundaries. In areas neighboring the boundaries, the equations of motion are solved by the newly proposed vortex method by Chorin. The major accomplishment of the new scheme is that it contains a simple way for merging the two methods at the interface of the two subdomains. The proposed algorithm is designed for use on the time-dependent equations but can be used on steady state problems as well. The method is tested on the popular, time-independent, square cavity problem, an example of a separated flow with closed streamlines. Numerical results are presented for a Reynolds number of 10 3 . (auth)

  10. Finite volume simulation of 2-D steady square lid driven cavity flow at high reynolds numbers

    Directory of Open Access Journals (Sweden)

    K. Yapici

    2013-12-01

    Full Text Available In this work, computer simulation results of steady incompressible flow in a 2-D square lid-driven cavity up to Reynolds number (Re 65000 are presented and compared with those of earlier studies. The governing flow equations are solved by using the finite volume approach. Quadratic upstream interpolation for convective kinematics (QUICK is used for the approximation of the convective terms in the flow equations. In the implementation of QUICK, the deferred correction technique is adopted. A non-uniform staggered grid arrangement of 768x768 is employed to discretize the flow geometry. Algebraic forms of the coupled flow equations are then solved through the iterative SIMPLE (Semi-Implicit Method for Pressure-Linked Equation algorithm. The outlined computational methodology allows one to meet the main objective of this work, which is to address the computational convergence and wiggled flow problems encountered at high Reynolds and Peclet (Pe numbers. Furthermore, after Re > 25000 additional vortexes appear at the bottom left and right corners that have not been observed in earlier studies.

  11. Modelling high Reynolds number wall-turbulence interactions in laboratory experiments using large-scale free-stream turbulence.

    Science.gov (United States)

    Dogan, Eda; Hearst, R Jason; Ganapathisubramani, Bharathram

    2017-03-13

    A turbulent boundary layer subjected to free-stream turbulence is investigated in order to ascertain the scale interactions that dominate the near-wall region. The results are discussed in relation to a canonical high Reynolds number turbulent boundary layer because previous studies have reported considerable similarities between these two flows. Measurements were acquired simultaneously from four hot wires mounted to a rake which was traversed through the boundary layer. Particular focus is given to two main features of both canonical high Reynolds number boundary layers and boundary layers subjected to free-stream turbulence: (i) the footprint of the large scales in the logarithmic region on the near-wall small scales, specifically the modulating interaction between these scales, and (ii) the phase difference in amplitude modulation. The potential for a turbulent boundary layer subjected to free-stream turbulence to 'simulate' high Reynolds number wall-turbulence interactions is discussed. The results of this study have encouraging implications for future investigations of the fundamental scale interactions that take place in high Reynolds number flows as it demonstrates that these can be achieved at typical laboratory scales.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

  12. Choice of boundary condition for lattice-Boltzmann simulation of moderate-Reynolds-number flow in complex domains.

    Science.gov (United States)

    Nash, Rupert W; Carver, Hywel B; Bernabeu, Miguel O; Hetherington, James; Groen, Derek; Krüger, Timm; Coveney, Peter V

    2014-02-01

    Modeling blood flow in larger vessels using lattice-Boltzmann methods comes with a challenging set of constraints: a complex geometry with walls and inlets and outlets at arbitrary orientations with respect to the lattice, intermediate Reynolds (Re) number, and unsteady flow. Simple bounce-back is one of the most commonly used, simplest, and most computationally efficient boundary conditions, but many others have been proposed. We implement three other methods applicable to complex geometries [Guo, Zheng, and Shi, Phys. Fluids 14, 2007 (2002); Bouzidi, Firdaouss, and Lallemand, Phys. Fluids 13, 3452 (2001); Junk and Yang, Phys. Rev. E 72, 066701 (2005)] in our open-source application hemelb. We use these to simulate Poiseuille and Womersley flows in a cylindrical pipe with an arbitrary orientation at physiologically relevant Re number (1-300) and Womersley (4-12) numbers and steady flow in a curved pipe at relevant Dean number (100-200) and compare the accuracy to analytical solutions. We find that both the Bouzidi-Firdaouss-Lallemand (BFL) and Guo-Zheng-Shi (GZS) methods give second-order convergence in space while simple bounce-back degrades to first order. The BFL method appears to perform better than GZS in unsteady flows and is significantly less computationally expensive. The Junk-Yang method shows poor stability at larger Re number and so cannot be recommended here. The choice of collision operator (lattice Bhatnagar-Gross-Krook vs multiple relaxation time) and velocity set (D3Q15 vs D3Q19 vs D3Q27) does not significantly affect the accuracy in the problems studied.

  13. A mechanism of thrust enhancement on a heaving plate due to flexibility at moderately low Reynolds numbers

    Science.gov (United States)

    Lin, Yung-Sheng; Tzeng, Yau-Ting; Chang, Chien-Cheng; Chu, Chin-Chou

    2017-11-01

    A numerical study is conducted to investigate the force mechanisms for a 3D heaving flexible plate from the perspective of a diagnostic force element analysis (Chang 1992). The problem is relevant to a simplified flapping fish-tail with the front edge held fixed in space. The flow is assumed to be laminar with the Reynolds numbers fixed at Re =200 or 500, and the Strouhal number St ranging from 0.1 to 0.6, and the flexure amplitude of the plate a0 for 0.1 to 0.25 (dimensionless). It is shown that heaving, whilst increasing thrust generation, also reduces the frictional drag, yet the flexibility promotes thrust generation at the expense of accruing more frictional drag. In the literature, the thrust exerted on the tail-mimicking plate is largely credited to the vortices in the wake. However, this study performs a regional force analysis to show that the vorticity in the wake region supplies approximately 20-30% of the total thrust, especially in the cases of strong thrust generation. Comparable contributions come also from the regions direct above and below the heaving plate (mainly including the attached vortices) as well as from the two side regions (mainly including the tip vortices) next to the flapping plate. In addition, the potential motion associated with the unsteady flapping and the contribution from the surface vorticity are non-negligible constituent force components. MOST, TAIWAN under Contacts NO. 105-2221-E-002-097-MY3 and NO. 105-2221-E-002 -105 -MY3.

  14. Jet Impingement Heat Transfer at High Reynolds Numbers and Large Density Variations

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    Jet impingement heat transfer from a round gas jet to a flat wall has been investigated numerically in a configuration with H/D=2, where H is the distance from the jet inlet to the wall and D is the jet diameter. The jet Reynolds number was 361000 and the density ratio across the wall boundary...... layer was 3.3 due to a substantial temperature difference of 1600K between jet and wall. Results are presented which indicate very high heat flux levels and it is demonstrated that the jet inlet turbulence intensity significantly influences the heat transfer results, especially in the stagnation region....... The results also show a noticeable difference in the heat transfer predictions when applying different turbulence models. Furthermore calculations were performed to study the effect of applying temperature dependent thermophysical properties versus constant properties and the effect of calculating the gas...

  15. Dissipative Effects on Inertial-Range Statistics at High Reynolds Numbers.

    Science.gov (United States)

    Sinhuber, Michael; Bewley, Gregory P; Bodenschatz, Eberhard

    2017-09-29

    Using the unique capabilities of the Variable Density Turbulence Tunnel at the Max Planck Institute for Dynamics and Self-Organization, Göttingen, we report experimental measurements in classical grid turbulence that uncover oscillations of the velocity structure functions in the inertial range. This was made possible by measuring extremely long time series of up to 10^{10} samples of the turbulent fluctuating velocity, which corresponds to O(10^{7}) integral length scales. The measurements were conducted in a well-controlled environment at a wide range of high Reynolds numbers from R_{λ}=110 up to R_{λ}=1600, using both traditional hot-wire probes as well as the nanoscale thermal anemometry probe developed at Princeton University. An implication of the observed oscillations is that dissipation influences the inertial-range statistics of turbulent flows at scales significantly larger than predicted by current models and theories.

  16. Modification of the mean near-wall velocity profile of a high-Reynolds number turbulent boundary layer with the injection of drag-reducing polymer solutions

    Science.gov (United States)

    Elbing, Brian R.; Perlin, Marc; Dowling, David R.; Ceccio, Steven L.

    2013-08-01

    The current study explores the influence of polymer drag reduction on the near-wall velocity distribution in a turbulent boundary layer (TBL) and its dependence on Reynolds number. Recent moderate Reynolds number direct numerical simulation and experimental studies presented in White et al. [Phys. Fluids 24, 021701 (2012)], 10.1063/1.3681862 have challenged the classical representation of the logarithmic dependence of the velocity profile for drag-reduced flows, especially at drag reduction levels above 40%. In the present study, high Reynolds number data from a drag reduced TBL is presented and compared to the observations of White et al. [Phys. Fluids 24, 021701 (2012)], 10.1063/1.3681862. Data presented here were acquired in the TBL flow on a 12.9-m-long flat plate at speeds to 20.3 m s-1, achieving momentum thickness based Reynolds number to 1.5 × 105, which is an order of magnitude greater than that available in the literature. Polyethylene oxide solutions with an average molecular weight of 3.9 × 106 g mol-1 were injected into the flow at various concentrations and volumetric fluxes to achieve a particular level of drag reduction. The resulting mean near-wall velocity profiles show distinctly different behavior depending on whether they fall in the low drag reduction (LDR) or the high drag reduction (HDR) regimes, which are nominally divided at 40% drag reduction. In the LDR regime, the classical view that the logarithmic slope remains constant at the Newtonian value and the intercept constant increases with increasing drag reduction appears to be valid. However, in the HDR regime the behavior is no longer universal. The intercept constant continues to increase linearly in proportion to the drag reduction level until a Reynolds-number-dependent threshold is achieved, at which point the intercept constant rapidly decreases to that predicted by the ultimate profile. The rapid decrease in the intercept constant is due to the corresponding increase in the

  17. The break-up of a viscous liquid drop in a high Reynolds number shear flow

    Science.gov (United States)

    Ng, Chin Hei; Aliseda, Alberto

    2015-11-01

    The break-up of a viscous liquid droplet in a sheared turbulent flow evolves in several steps, the most visually dominant of which is the formation of high aspect ratio ligaments. This feature takes them apart from the various break-up models based on the Hinze-Kolmogorov paradigm of eddy-spherical particle collisions. We investigate the development of ligaments in a high Reynolds number (up to 250,000) submerged round jet, within the high viscosity, near-unity density ratio regime. Unlike in H-K theory, applicable to the break-up of inviscid fluid particles, break-up of inertial-scale viscous droplets occurs through a sequence of eddy collisions and long-term deformation, as evidenced by measurements of the aspect ratio that fluctuates and increases progressively during the deformation stage, and results in non-binary break-up. Additionally, the ligament formation stretches a droplet to multiple times its original size, bringing the influence of integral-scale structures. High speed imaging has been statistically analyzed to inform and validate theoretical models for the break-up time and the break-up probability. In addition, a particle size scaling model has been developed and compared with the experimental measurements of the frozen-state particle size.

  18. Experimental Investigation of Vortex Shedding in High Reynolds Number Flow Over Compressor Blades in Cascade

    National Research Council Canada - National Science Library

    Lim, Choon

    2003-01-01

    .... Vortex shedding was determined to be a leading edge phenomenon as periodic shedding was only detected on the pressure side of the wake, The relationship between vortex shedding frequency and Reynolds...

  19. Mesh Generation and Adaption for High Reynolds Number RANS Computations, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal offers to provide NASA with an automatic mesh generator for the simulation of aerodynamic flows using Reynolds-Averages Navier-Stokes (RANS) models....

  20. Mesh Generation and Adaption for High Reynolds Number RANS Computations, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal offers to provide NASA with an automatic mesh generator for the simulation of aerodynamic flows using Reynolds-Averages Navier-Stokes (RANS) models....

  1. High-Reynolds-number turbulent-boundary-layer wall-pressure fluctuations with dilute polymer solutions

    Science.gov (United States)

    Elbing, Brian R.; Winkel, Eric S.; Ceccio, Steven L.; Perlin, Marc; Dowling, David R.

    2010-08-01

    Wall-pressure fluctuations were investigated within a high-Reynolds-number turbulent boundary layer (TBL) modified by the addition of dilute friction-drag-reducing polymer solutions. The experiment was conducted at the U.S. Navy's Large Cavitation Channel on a 12.9 m long flat-plate test model with the surface hydraulically smooth (k+<0.2) and achieving downstream-distance-based Reynolds numbers to 220×106. The polymer (polyethylene oxide) solution was injected into the TBL through a slot in the surface. The primary flow diagnostics were skin-friction drag balances and an array of flush-mounted dynamic pressure transducers 9.8 m from the model leading edge. Parameters varied included the free-stream speed (6.7, 13.4, and 20.2 m s-1) and the injection condition (polymer molecular weight, injection concentration, and volumetric injection flux). The behavior of the pressure spectra, convection velocity, and coherence, regardless of the injection condition, were determined primarily based on the level of drag reduction. Results were divided into two regimes dependent on the level of polymer drag reduction (PDR), nominally separated at a PDR of 40%. The low-PDR regime is characterized by decreasing mean-square pressure fluctuations and increasing convection velocity with increasing drag reduction. This shows that the decrease in the pressure spectra with increasing drag reduction is due in part to the moving of the turbulent structures from the wall. Conversely, with further increases in drag reduction, the high-PDR regime has negligible variation in the mean-squared pressure fluctuations and convection velocity. The convection velocity remains constant at approximately 10% above the baseline-flow convection velocity, which suggests that the turbulent structures no longer move farther from the wall with increasing drag reduction. In light of recent numerical work, the coherence results indicate that in the low-PDR regime, the turbulent structures are being elongated in

  2. A Doppler Sensor Array for High-Resolution Measurements of the Wavenumber-Frequency Spectrum of the Turbulent Wall Pressure at High Reynold Numbers

    National Research Council Canada - National Science Library

    Naguib, Ahmed

    2003-01-01

    .... Moreover, analysis of typical wall-pressure spectra beneath high- and low-Reynolds-number, boundary layers in light of these limits underlines the potential advantage of the new sensor in resolving...

  3. submitter Superconducting instrumentation for high Reynolds turbulence experiments with low temperature gaseous helium

    CERN Document Server

    Pietropinto, S; Baudet, C; Castaing, B; Chabaud, B; Gagne, Y; Hébral, B; Ladam, Y; Lebrun, P; Pirotte, O; Roche, P

    2003-01-01

    Turbulence is of common experience and of high interest for industrial applications, despite its physical grounds is still not understood. Cryogenic gaseous helium gives access to extremely high Reynolds numbers (Re). We describe an instrumentation hosted in CERN, which provides a 6 kW @ 4.5 K helium refrigerator directly connected to the experiment. The flow is a round jet; the flow rates range from 20 g/s up to 260 g/s at 4.8 K and about 1.2 bar, giving access to the highest controlled Re flow ever developed. The experimental challenge lies in the range of scales which have to be investigated: from the smallest viscous scale η, typically 1 μm at Re=107 to the largest L∼10 cm. The corresponding frequencies: f=v/η can be as large as 1 MHz. The development of an original micrometric superconducting anemometer using a hot spot and its characteristics will be discussed together with its operation and the perspectives associated with superconducting anemometry.

  4. Evaluation of machine learning algorithms for prediction of regions of high Reynolds averaged Navier Stokes uncertainty

    Science.gov (United States)

    Ling, J.; Templeton, J.

    2015-08-01

    Reynolds Averaged Navier Stokes (RANS) models are widely used in industry to predict fluid flows, despite their acknowledged deficiencies. Not only do RANS models often produce inaccurate flow predictions, but there are very limited diagnostics available to assess RANS accuracy for a given flow configuration. If experimental or higher fidelity simulation results are not available for RANS validation, there is no reliable method to evaluate RANS accuracy. This paper explores the potential of utilizing machine learning algorithms to identify regions of high RANS uncertainty. Three different machine learning algorithms were evaluated: support vector machines, Adaboost decision trees, and random forests. The algorithms were trained on a database of canonical flow configurations for which validated direct numerical simulation or large eddy simulation results were available, and were used to classify RANS results on a point-by-point basis as having either high or low uncertainty, based on the breakdown of specific RANS modeling assumptions. Classifiers were developed for three different basic RANS eddy viscosity model assumptions: the isotropy of the eddy viscosity, the linearity of the Boussinesq hypothesis, and the non-negativity of the eddy viscosity. It is shown that these classifiers are able to generalize to flows substantially different from those on which they were trained. Feature selection techniques, model evaluation, and extrapolation detection are discussed in the context of turbulence modeling applications.

  5. A Sweeping Jet Application on a High Reynolds Number Semispan Supercritical Wing Configuration

    Science.gov (United States)

    Jones, Gregory S.; Milholen, William E., II; Chan, David T.; Melton, Latunia; Goodliff, Scott L.; Cagle, C. Mark

    2017-01-01

    The FAST-MAC circulation control model was modified to test an array of unsteady sweeping-jet actuators at realistic flight Reynolds numbers in the National Transonic Facility at the NASA Langley Research Center. Two types of sweeping jet actuators were fabricated using rapid prototype techniques, and directed over a 15% chord simple-hinged flap. The model was configured for low-speed high-lift testing with flap deflections of 30 deg and 60 deg, and a transonic cruise configuration having a 0 deg flap deflection. For the 30 deg flap high-lift configuration, the sweeping jets achieved comparable lift performance in the separation control regime, while reducing the mass flow by 54% as compared to steady blowing. The sweeping jets however were not effective for the 60 deg flap. For the transonic cruise configuration, the sweeping jets reduced the drag by 3.3% at an off-design condition. The drag reduction for the design lift coefficient for the sweeping jets offer is only half the drag reduction shown for the steady blowing case (6.5%), but accomplished this with a 74% reduction in mass flow.

  6. Linear drag law for high-Reynolds-number flow past an oscillating body

    Science.gov (United States)

    Agre, Natalie; Childress, Stephen; Zhang, Jun; Ristroph, Leif

    2016-07-01

    An object immersed in a fast flow typically experiences fluid forces that increase with the square of speed. Here we explore how this high-Reynolds-number force-speed relationship is affected by unsteady motions of a body. Experiments on disks that are driven to oscillate while progressing through air reveal two distinct regimes: a conventional quadratic relationship for slow oscillations and an anomalous scaling for fast flapping in which the time-averaged drag increases linearly with flow speed. In the linear regime, flow visualization shows that a pair of counterrotating vortices is shed with each oscillation and a model that views a train of such dipoles as a momentum jet reproduces the linearity. We also show that appropriate scaling variables collapse the experimental data from both regimes and for different oscillatory motions into a single drag-speed relationship. These results could provide insight into the aerodynamic resistance incurred by oscillating wings in flight and they suggest that vibrations can be an effective means to actively control the drag on an object.

  7. High Reynolds number rough wall turbulent boundary layer experiments using Braille surfaces

    Science.gov (United States)

    Harris, Michael; Monty, Jason; Nova, Todd; Allen, James; Chong, Min

    2007-11-01

    This paper details smooth, transitional and fully rough turbulent boundary layer experiments in the New Mexico State high Reynolds number rough wall wind tunnel. The initial surface tested was generated with a Braille printer and consisted of an uniform array of Braille points. The average point height being 0.5mm, the spacing between the points in the span was 0.5mm and the surface consisted of span wise rows separated by 4mm. The wavelength to peak ratio was 8:1. The boundary layer thickness at the measurement location was 190mm giving a large separation of roughness height to layer thickness. The maximum friction velocity was uτ=1.5m/s at Rex=3.8 x10^7. Results for the skin friction co-efficient show that this surface follows a Nikuradse type inflectional curve and that Townsends outer layer similarity hypothesis is valid for rough wall flows with a large separation of scales. Mean flow and turbulence statistics will be presented.

  8. Conditional analysis near strong shear layers in DNS of isotropic turbulence at high Reynolds number

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Takashi; Kaneda, Yukio [Graduate School of Engineering, Nagoya University (Japan); Hunt, Julian C R, E-mail: ishihara@cse.nagoya-u.ac.jp [University College of London (United Kingdom)

    2011-12-22

    Data analysis of high resolution DNS of isotropic turbulence with the Taylor scale Reynolds number R{sub {lambda}} = 1131 shows that there are thin shear layers consisting of a cluster of strong vortex tubes with typical diameter of order 10{eta}, where {eta} is the Kolmogorov length scale. The widths of the layers are of the order of the Taylor micro length scale. According to the analysis of one of the layers, coarse grained vorticity in the layer are aligned approximately in the plane of the layer so that there is a net mean shear across the layer with a mean velocity jump of the order of the root-mean-square of the fluctuating velocity, and energy dissipation averaged over the layer is larger than ten times the average over the whole flow. The mean and the standard deviation of the energy transfer T(x, {kappa}) from scales larger than 1/{kappa} to scales smaller than 1/{kappa} at position x are largest within the layers (where the most intense vortices and dissipation occur), but are also large just outside the layers (where viscous stresses are weak), by comparison with the average values of T over the whole region. The DNS data are consistent with exterior fluctuation being damped/filtered at the interface of the layer and then selectively amplified within the layer.

  9. Using Computational Fluid Dynamics and Experiments to Design Sweeping Jets for High Reynolds Number Cruise Configurations

    Science.gov (United States)

    Jones, Gregory S.; Milholen, William E., II; Fell, Jared S.; Webb, Sandy R.; Cagle, C. Mark

    2016-01-01

    The application of a sweeping jet actuator to a circulation control system was initiated by a risk reduction series of experiments to optimize the authority of a single sweeping jet actuator. The sweeping jet design was integrated into the existing Fundamental Aerodynamic Subsonic Transonic- Modular Active Control (FAST-MAC) model by replacing the steady blowing system with an array of thirty-nine sweeping jet cartridges. A constant slot height to wing chord ratio was similar to the steady blowing configuration resulting in each actuator having a unique in size for the sweeping jet configuration. While this paper will describe the scaling and optimization of the actuators for future high Reynolds number applications, the major focus of this effort was to target the transonic flight regime by increasing the amplitude authority of the actuator. This was accomplished by modifying the diffuser of the sweeping jet actuator, and this paper highlights twelve different diffuser designs. The experimental portion of this work was completed in the NASA Langley National Transonic Facility.

  10. Energetics and dynamics of droplet evaporation in high temperature intermediate Reynolds number flows

    Science.gov (United States)

    Renksizbulut, M.

    Nusselt Numbers and drag coefficients of single-component liquid droplets and solid spheres in high temperature, intermediate Reynolds Number flows were investigated. The evaporation of suspended water, Methanol and n-Heptane droplets were followed in laminar air streams up to 1059 K in temperature using a steady-state measurement technique. It is found that the dynamic blowing effect of evaporation causes large reductions in heat transfer rates, and that the film conditions constitute an appropriate reference state for the evaluation of thermophysical properties. The numerical results indicate that the blowing effect of evaporation on momentum transfer is to reduce friction drag very significantly but at the same time increase pressure drag by almost an equal amount; the net effect on the total drag force being only a marginal reduction. In all cases, it is found that thermophysical property variations play a very dominant role in reducing the drag forces acting on cold particles. Results are analysed and a correlation for stagnation-point heat transfer is also presented.

  11. Scaling and interaction of self-similar modes in models of high Reynolds number wall turbulence.

    Science.gov (United States)

    Sharma, A S; Moarref, R; McKeon, B J

    2017-03-13

    Previous work has established the usefulness of the resolvent operator that maps the terms nonlinear in the turbulent fluctuations to the fluctuations themselves. Further work has described the self-similarity of the resolvent arising from that of the mean velocity profile. The orthogonal modes provided by the resolvent analysis describe the wall-normal coherence of the motions and inherit that self-similarity. In this contribution, we present the implications of this similarity for the nonlinear interaction between modes with different scales and wall-normal locations. By considering the nonlinear interactions between modes, it is shown that much of the turbulence scaling behaviour in the logarithmic region can be determined from a single arbitrarily chosen reference plane. Thus, the geometric scaling of the modes is impressed upon the nonlinear interaction between modes. Implications of these observations on the self-sustaining mechanisms of wall turbulence, modelling and simulation are outlined.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

  12. NUMERICAL SIMULATIONS OF FLOW BEHAVIOR IN DRIVEN CAVITY AT HIGH REYNOLDS NUMBERS

    Directory of Open Access Journals (Sweden)

    Fudhail Bin Abdul Munir

    2012-02-01

    Full Text Available In recent years, due to rapidly increasing computational power, computational methods have become the essential tools to conduct researches in various engineering fields.  In parallel to the development of ultra high speed digital computers, computational fluid dynamics (CFD has become the new third approach apart from theory and experiment in the philosophical study and development of fluid dynamics.  Lattice Boltzmann method (LBM is an alternative method to conventional CFD.  LBM is relatively new approach that uses simple microscopic models to simulate complicated microscopic behavior of transport phenomena.  In this paper, fluid flow behaviors of steady incompressible flow inside lid driven square cavity are studied.  Numerical calculations are conducted for different Reynolds numbers by using Lattice Boltzmann scheme.  The objective of the paper is to demonstrate the capability of this lattice Boltzmann scheme for engineering applications particularly in fluid transport phenomena. Keywords-component; lattice Boltzmann method, lid driven cavity, computational fluid dynamics.

  13. Numerical simulations of separated flows at moderate Reynolds numbers appropriate for turbine blades and unmanned aero vehicles

    International Nuclear Information System (INIS)

    Castiglioni, G.; Domaradzki, J.A.; Pasquariello, V.; Hickel, S.; Grilli, M.

    2014-01-01

    Highlights: • The present study evaluate LES techniques and IB method to simulate separated flows. • Simulations have been performed with an IB code and a commercial code. • The benchmark flow is a laminar separation bubble around an airfoil. • It is concluded that IB methods are appropriate only for high resolution DNS and LES. • High fidelity LES with 1% of DNS resolution can be performed. - Abstract: Flows over airfoils and blades in rotating machinery, for unmanned and micro-aerial vehicles, wind turbines, and propellers consist of a laminar boundary layer near the leading edge that is often followed by a laminar separation bubble and transition to turbulence further downstream. Typical RANS turbulence models are inadequate for such flows. Direct numerical simulation (DNS) is the most reliable, but is also the most computationally expensive alternative. This work assesses the capability of Immersed Boundary (IB) methods and Large Eddy Simulations (LES) to reduce the computational requirements for such flows and still provide high quality results. Two-dimensional and three-dimensional simulations of a laminar separation bubble on a NACA-0012 airfoil at Re c =5×10 4 at 5° of incidence have been performed with an IB code and a commercial code using body fitted grids. Several Subgrid Scale (SGS) models have been implemented in both codes and their performance evaluated. For the two-dimensional simulations with the IB method the results show good agreement with DNS benchmark data for the pressure coefficient C p and the friction coefficient C f but only when using dissipative numerical schemes. There is evidence that this behavior can be attributed to the ability of dissipative schemes to damp numerical noise coming from the IB. For the three-dimensional simulations the results show a good prediction of the separation point, but inaccurate prediction of the reattachment point unless full DNS resolution is used. The commercial code shows good agreement

  14. Marine Hydrokinetic (MHK) Energy Conversion Research at UNH: From Fundamental Studies of Hydrofoil Sections, to Moderate Reynolds Number Turbine Tests in a Tow Tank, to Open Water Deployments at Tidal Energy Test Sites (Invited)

    Science.gov (United States)

    Wosnik, M.; Bachant, P.; Nedyalkov, I.; Rowell, M.; Dufresne, N.; Lyon, V.

    2013-12-01

    We report on research related to MHK turbines at the Center for Ocean Renewable Energy (CORE) at the University of New Hampshire (UNH). The research projects span varies scales, levels of complexity and environments - from fundamental studies of hydrofoil sections in a high speed water tunnel, to moderate Reynolds number turbine tests with inflow and wake studies in a large cross-section tow tank, to deployments of highly instrumented process models at tidal energy test sites in New England. A concerted effort over the past few years has brought significant new research infrastructure for marine hydrokinetic energy conversion online at UNH-CORE. It includes: a high-speed cavitation tunnel with independent control of velocity and pressure; a highly accurate tow mechanism, turbine test bed and wake traversing system for the 3.7m x 2.4m cross-section UNH tow tank; a 10.7m x 3.0m tidal energy test platform which can accommodate turbines up to 1.5m in diameter, for deployments at the UNH-CORE Tidal Energy Test Site in Great Bay Estuary, NH, a sheltered 'nursery site' suitable for intermediate scale tidal energy conversion device testing with peak currents typically above 2 m/s during each tidal cycle. Further, a large boundary layer wind tunnel, the new UNH Flow Physics Facility (W6.0m x H2.7m xL72m) is being used for detailed turbine wake studies, producing data and insight also applicable to MHK turbines in low Froude number deployments. Bi-directional hydrofoils, which perform equally well in either flow direction and could avoid the use of complex and maintenance-intensive yaw or blade pitch mechanisms, are being investigated theoretically, numerically and experimentally. For selected candidate shapes lift, drag, wake, and cavitation inception/desinence are measured. When combined with a cavitation inception model for MHK turbines, this information can be used to prescribe turbine design/operational parameters. Experiments were performed with a 1m diameter and 1m

  15. Introduction: Scaling and structure in high Reynolds number wall-bounded flows

    International Nuclear Information System (INIS)

    McKeon, B.J.; Sreenivasan, K.R.

    2007-05-01

    The papers discussed in this report are dealing with the following aspects: Fundamental scaling relations for canonical flows and asymptotic approach to infinite Reynolds numbers; large and very large scales in near-wall turbulences; the influence of roughness and finite Reynolds number effects; comparison between internal and external flows and the universality of the near-wall region; qualitative and quantitative models of the turbulent boundary layer; the neutrally stable atmospheric surface layer as a model for a canonical zero-pressure-gradient boundary layer (author)

  16. High conversion heavy water moderated reactor

    International Nuclear Information System (INIS)

    Miyawaki, Yoshio; Wakabayashi, Toshio.

    1989-01-01

    In the present invention, fuel rods using uranium-plutonium oxide mixture fuels are arranged in a square lattice at the same pitch as that in light water cooled reactor and heavy water moderators are used. Accordingly, the volume ratio (Vm/Vf) between the moderator and the fuel can be, for example, of about 2. When heavy water is used for the moderator (coolant), since the moderating effect of heavy water is lower than that of light water, a high conversion ratio of not less than 0.8 can be obtained even if the fuel rod arrangement is equal to that of PWR (Vm/Vf about 2). Accordingly, it is possible to avoid problems caused by dense arrangement of fuel rods as in high conversion rate light water cooled reactors. That is, there are no more troubles in view of thermal hydrodynamic characteristics, re-flooding upon loss of coolant accident, etc., as well as the fuel production cost is not increased. (K.M.)

  17. Influence of elbow curvature on flow structure at elbow outlet under high Reynolds number condition

    Energy Technology Data Exchange (ETDEWEB)

    Ono, A., E-mail: ono.ayako@jaea.go.jp [Oarai Research and Development Center, Japan Atomic Energy Agency, Narita 4002, Oarai, Ibaraki 311-1393 (Japan); Kimura, N.; Kamide, H.; Tobita, A. [Oarai Research and Development Center, Japan Atomic Energy Agency, Narita 4002, Oarai, Ibaraki 311-1393 (Japan)

    2011-11-15

    In the design of Japan Sodium-cooled Fast Reactor (JSFR), coolant velocity is beyond 9 m/s in the primary hot leg pipe of 1.27 m diameter. The Reynolds number in the piping reaches 4.2 Multiplication-Sign 10{sup 7}. Moreover, a short-elbow is adopted in the hot leg pipe in order to achieve compact plant layout and to reduce plant construction cost. Therefore, the flow-induced vibration (FIV) arising from the piping geometry may occur in the short-elbow pipe. The FIV is due to the excitation source which is caused by the pressure fluctuation in the pipe. The pressure fluctuation in the pipe is closely related with the velocity fluctuation. As the first step of clarification of the FIV mechanism, it is important to grasp the mechanism of flow fluctuation in the elbow. In this study, water experiments with two types of elbows with different curvature ratios were conducted in order to investigate the interaction between flow separation and the secondary flow due to the elbow curvature. The experiments were conducted with the short-elbow and the long-elbow under Re = 1.8 Multiplication-Sign 10{sup 5} and 5.4 Multiplication-Sign 10{sup 5} conditions. The velocity fields in the elbows were measured using a high-speed Particle Image Velocimetry (PIV). The time-series of axial velocity fields and the cross-section velocity fields obtained by the high-speed PIV measurements revealed the unsteady and complex flow structure in the elbow. The flow separation always occurred in the short-elbow while the flow separation occurred intermittently in the long-elbow case. The circumferential secondary flows in clockwise and counterclockwise directions flowed forward downstream of reattachment point alternately in both elbows.

  18. High and Low Reynolds number Measurements in a Room with an Impinging Isothermal Jet

    DEFF Research Database (Denmark)

    Skovgaard, M.; Hyldgaard, C. E.; Nielsen, Peter V.

    The present paper, which is within the work of the lEA - annex 20, presents a series of full-scale velocity measurements in a room with isothermal mixing ventilation. The measurements are in the Reynolds number range 1000 - 7000 based on inlet dimensions. This means that a transition from laminar...

  19. Status and future prospects of using numerical methods to study complex flows at High Reynolds numbers

    Science.gov (United States)

    Maccormack, R. W.

    1978-01-01

    The calculation of flow fields past aircraft configuration at flight Reynolds numbers is considered. Progress in devising accurate and efficient numerical methods, in understanding and modeling the physics of turbulence, and in developing reliable and powerful computer hardware is discussed. Emphasis is placed on efficient solutions to the Navier-Stokes equations.

  20. Summary of the Blind Test Campaign to predict the High Reynolds number performance of DU00-W-210 airfoil

    DEFF Research Database (Denmark)

    Yilmaz, Özlem Ceyhan; Pires, Oscar; Munduate, Xabier

    2017-01-01

    This paper summarizes the results of a blind test campaign organized in the AVATAR project to predict the high Reynolds number performance of a wind turbine airfoil for wind turbine applications. The DU00-W-210 airfoil was tested in the DNW-HDG pressurized wind tunnel in order to investigate...... the flow at high Reynolds number range from 3 to 15 million which is the operating condition of the future large 10MW+ offshore wind turbine rotors. The results of the experiment was used in a blind test campaign to test the prediction capability of the CFD tools used in the wind turbine rotor simulations....... As a result of the blind test campaign it was found that although the codes are in general capable of predicting increased max lift and decreased minimum drag with Re number, the Re trend predictions in particular the glide ratio (lift over drag) need further improvement. In addition to that, the significant...

  1. Phase relations in a forced turbulent boundary layer: implications for modelling of high Reynolds number wall turbulence.

    Science.gov (United States)

    Duvvuri, Subrahmanyam; McKeon, Beverley

    2017-03-13

    Phase relations between specific scales in a turbulent boundary layer are studied here by highlighting the associated nonlinear scale interactions in the flow. This is achieved through an experimental technique that allows for targeted forcing of the flow through the use of a dynamic wall perturbation. Two distinct large-scale modes with well-defined spatial and temporal wavenumbers were simultaneously forced in the boundary layer, and the resulting nonlinear response from their direct interactions was isolated from the turbulence signal for the study. This approach advances the traditional studies of large- and small-scale interactions in wall turbulence by focusing on the direct interactions between scales with triadic wavenumber consistency. The results are discussed in the context of modelling high Reynolds number wall turbulence.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

  2. LES of High-Reynolds-Number Coanda Flow Separating from a Rounded Trailing Edge of a Circulation Control Airfoil

    Science.gov (United States)

    Nichino, Takafumi; Hahn, Seonghyeon; Shariff, Karim

    2010-01-01

    This slide presentation reviews the Large Eddy Simulation of a high reynolds number Coanda flow that is separated from a round trailing edge of a ciruclation control airfoil. The objectives of the study are: (1) To investigate detailed physics (flow structures and statistics) of the fully turbulent Coanda jet applied to a CC airfoil, by using LES (2) To compare LES and RANS results to figure out how to improve the performance of existing RANS models for this type of flow.

  3. Moderate resolution spectrophotometry of high redshift quasars

    Science.gov (United States)

    Schneider, Donald P.; Schmidt, Maarten; Gunn, James E.

    1991-01-01

    A uniform set of photometry and high signal-to-noise moderate resolution spectroscopy of 33 quasars with redshifts larger than 3.1 is presented. The sample consists of 17 newly discovered quasars (two with redshifts in excess of 4.4) and 16 sources drawn from the literature. The objects in this sample have r magnitudes between 17.4 and 21.4; their luminosities range from -28.8 to -24.9. Three of the 33 objects are broad absorption line quasars. A number of possible high redshift damped Ly-alpha systems were found.

  4. Discrete-Roughness-Element-Enhanced Swept-Wing Natural Laminar Flow at High Reynolds Numbers

    Science.gov (United States)

    Malik, Mujeeb; Liao, Wei; Li, Fei; Choudhari, Meelan

    2015-01-01

    Nonlinear parabolized stability equations and secondary-instability analyses are used to provide a computational assessment of the potential use of the discrete-roughness-element technology for extending swept-wing natural laminar flow at chord Reynolds numbers relevant to transport aircraft. Computations performed for the boundary layer on a natural-laminar-flow airfoil with a leading-edge sweep angle of 34.6 deg, freestream Mach number of 0.75, and chord Reynolds numbers of 17 × 10(exp 6), 24 × 10(exp 6), and 30 × 10(exp 6) suggest that discrete roughness elements could delay laminar-turbulent transition by about 20% when transition is caused by stationary crossflow disturbances. Computations show that the introduction of small-wavelength stationary crossflow disturbances (i.e., discrete roughness element) also suppresses the growth of most amplified traveling crossflow disturbances.

  5. DRE-Enhanced Swept-Wing Natural Laminar Flow at High Reynolds Numbers

    Science.gov (United States)

    Malik, Mujeeb; Liao, Wei; Li, Fe; Choudhari, Meelan

    2013-01-01

    Nonlinear parabolized stability equations and secondary instability analyses are used to provide a computational assessment of the potential use of the discrete roughness elements (DRE) technology for extending swept-wing natural laminar flow at chord Reynolds numbers relevant to transport aircraft. Computations performed for the boundary layer on a natural laminar flow airfoil with a leading-edge sweep angle of 34.6deg, free-stream Mach number of 0.75 and chord Reynolds numbers of 17 x 10(exp 6), 24 x 10(exp 6) and 30 x 10(exp 6) suggest that DRE could delay laminar-turbulent transition by about 20% when transition is caused by stationary crossflow disturbances. Computations show that the introduction of small wavelength stationary crossflow disturbances (i.e., DRE) also suppresses the growth of most amplified traveling crossflow disturbances.

  6. Theory of viscous transonic flow over airfoils at high Reynolds number

    Science.gov (United States)

    Melnik, R. E.; Chow, R.; Mead, H. R.

    1977-01-01

    This paper considers viscous flows with unseparated turbulent boundary layers over two-dimensional airfoils at transonic speeds. Conventional theoretical methods are based on boundary layer formulations which do not account for the effect of the curved wake and static pressure variations across the boundary layer in the trailing edge region. In this investigation an extended viscous theory is developed that accounts for both effects. The theory is based on a rational analysis of the strong turbulent interaction at airfoil trailing edges. The method of matched asymptotic expansions is employed to develop formal series solutions of the full Reynolds equations in the limit of Reynolds numbers tending to infinity. Procedures are developed for combining the local trailing edge solution with numerical methods for solving the full potential flow and boundary layer equations. Theoretical results indicate that conventional boundary layer methods account for only about 50% of the viscous effect on lift, the remaining contribution arising from wake curvature and normal pressure gradient effects.

  7. The evolution of the flame surface in turbulent premixed jet flames at high Reynolds number

    Science.gov (United States)

    Luca, Stefano; Attili, Antonio; Bisetti, Fabrizio

    2017-11-01

    A set of direct numerical simulations of turbulent premixed flames in a spatially developing turbulent slot burner at four Reynolds number is presented. This configuration is of interest since it displays turbulent production by mean shear as in real combustion devices. The gas phase hydrodynamics are modeled with the reactive, unsteady Navier-Stokes equations in the low Mach number limit, with finite-rate chemistry consisting of 16 species and 73 reactions. For the highest jet Reynolds number of 22 ×103, 22 Billion grid points are employed. The jet consists of a lean methane/air mixture at 4 atm and preheated to 800 K. The analysis of stretch statistics shows that the mean total stretch is close to zero. Mean stretch decreases moving downstream from positive to negative values, suggesting a formation of surface area in the near field and destruction at the tip of the flame; the mean contribution of the tangential strain term is positive, while the mean contribution of the propagative term is always negative. Positive values of stretch are due to the tangential strain rate term, while large negative values are associated with the propagative term. Increasing Reynolds number is found to decrease the correlation between stretch and the single contributions.

  8. Large scale Direct Numerical Simulation of premixed turbulent jet flames at high Reynolds number

    Science.gov (United States)

    Attili, Antonio; Luca, Stefano; Lo Schiavo, Ermanno; Bisetti, Fabrizio; Creta, Francesco

    2016-11-01

    A set of direct numerical simulations of turbulent premixed jet flames at different Reynolds and Karlovitz numbers is presented. The simulations feature finite rate chemistry with 16 species and 73 reactions and up to 22 Billion grid points. The jet consists of a methane/air mixture with equivalence ratio ϕ = 0 . 7 and temperature varying between 500 and 800 K. The temperature and species concentrations in the coflow correspond to the equilibrium state of the burnt mixture. All the simulations are performed at 4 atm. The flame length, normalized by the jet width, decreases significantly as the Reynolds number increases. This is consistent with an increase of the turbulent flame speed due to the increased integral scale of turbulence. This behavior is typical of flames in the thin-reaction zone regime, which are affected by turbulent transport in the preheat layer. Fractal dimension and topology of the flame surface, statistics of temperature gradients, and flame structure are investigated and the dependence of these quantities on the Reynolds number is assessed.

  9. Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

    International Nuclear Information System (INIS)

    Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

    2010-01-01

    Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

  10. Experimental validation of the design method to prevent flow-induced vibration in high Reynolds-number

    International Nuclear Information System (INIS)

    Sakai, Takaaki; Yamaguchi, Akira; Morisita, Masaki; Iwata, Koji

    1998-08-01

    The incident of sodium leakage from a main pipe of the secondary heat transport system of Monju fast breeder reactor was caused by the failure of a thermometer well. 'Flow-induced vibration design guide for thermometer wells' (express as 'design guide') was proposed by PNC Working Group to prevent the same cause of the sodium leak incident in future. On this report, applicability of the 'design guide' was estimated to plant conditions in high Reynolds-number(approximately 3x10 5 ∼ 3x10 6 ) involving the supercritical region, by measured data on a vortex synchronized vibration and a turbulence induced vibration. Experiments were performed for cylindrical and taper shaped types of test pieces. As results, reduced velocity (Vr) at onsets of the inline synchronized vibration were evaluated to be grater than 1.0 in the range of experimental conditions. Fluctuating drag and lift coefficients, which were evaluated from power spectrum of turbulence for Vr < 1.0 condition, were 0.01 ∼ 0.05 for drag direction and 0.04 ∼ 0.13 for lift direction. The fluctuating drag and lift coefficients used in the 'design guide' were estimated to be conservative by comparison with these data. Correlation lengths for a cylinder and a taper shaped one in the high Reynolds-number region were estimated to be 1.6 times of the diameter(D) in the maximum case. The measured value of correlation length is enough smaller than the 'design guide' value of 3.0D. Displacement amplitudes of test pieces for Vr < 1.0 conditions were enough smaller (fives times) than calculated values based on the 'design guide'. Consequently, the applicability of the design guide' was confirmed in the range of experiments involving the super critical Reynolds-number region. (author)

  11. Large-Eddy Simulation of a High Reynolds Number Flow Around a Cylinder Including Aeroacoustic Predictions

    Science.gov (United States)

    Spyropoulos, Evangelos T.; Holmes, Bayard S.

    1997-01-01

    The dynamic subgrid-scale model is employed in large-eddy simulations of flow over a cylinder at a Reynolds number, based on the diameter of the cylinder, of 90,000. The Centric SPECTRUM(trademark) finite element solver is used for the analysis. The far field sound pressure is calculated from Lighthill-Curle's equation using the computed fluctuating pressure at the surface of the cylinder. The sound pressure level at a location 35 diameters away from the cylinder and at an angle of 90 deg with respect to the wake's downstream axis was found to have a peak value of approximately 110 db. Slightly smaller peak values were predicted at the 60 deg and 120 deg locations. A grid refinement study suggests that the dynamic model demands mesh refinement beyond that used here.

  12. Synchronization of vortex formation frequency with the body motion frequency at high Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Luiz Antonio Alcantara [Federal University of Itajuba (UNIFEI), MG (Brazil). Inst. of Mechanical Engineering], E-mail: luizantp@unifei.edu.br; Hirata, Miguel Hiroo [State University of Rio de Janeiro (FAT/UERJ), Resende, RJ (Brazil). Fac. de Tecnologia], E-mail: hirata@fat.uerj.br

    2010-07-01

    Understanding vortex induced vibrations is of great importance in the design of a variety of offshore engineering structures, nuclear plant components and cylindrical elements in tube-bank heat exchangers, for example. If a body is placed in a flow, it experiences alternating lift and drag forces caused by the asymmetric formation of vortices, which can cause a structure to vibrate. One of the most interesting features of this flow is the phenomenon of lock-in which is observed when the vortex shedding frequency is close to the body oscillation frequency. This paper presents the results of numerical experiments on vortex shedding from a circular cylinder vibrating in-line or transversely with an incident uniform flow at Reynolds number of 1.0 x 10{sup 5}. The frequencies of the lift and drag coefficients are compared with the body motion frequency when the frequency ratio is about unity. (author)

  13. Calibration of the 7—Equation Transition Model for High Reynolds Flows at Low Mach

    Science.gov (United States)

    Colonia, S.; Leble, V.; Steijl, R.; Barakos, G.

    2016-09-01

    The numerical simulation of flows over large-scale wind turbine blades without considering the transition from laminar to fully turbulent flow may result in incorrect estimates of the blade loads and performance. Thanks to its relative simplicity and promising results, the Local-Correlation based Transition Modelling concept represents a valid way to include transitional effects into practical CFD simulations. However, the model involves coefficients that need tuning. In this paper, the γ—equation transition model is assessed and calibrated, for a wide range of Reynolds numbers at low Mach, as needed for wind turbine applications. An aerofoil is used to evaluate the original model and calibrate it; while a large scale wind turbine blade is employed to show that the calibrated model can lead to reliable solutions for complex three-dimensional flows. The calibrated model shows promising results for both two-dimensional and three-dimensional flows, even if cross-flow instabilities are neglected.

  14. Modification of the large-scale features of high Reynolds number wall turbulence by passive surface obtrusions

    Energy Technology Data Exchange (ETDEWEB)

    Monty, J.P.; Lien, K.; Chong, M.S. [University of Melbourne, Department of Mechanical Engineering, Parkville, VIC (Australia); Allen, J.J. [New Mexico State University, Department of Mechanical Engineering, Las Cruces, NM (United States)

    2011-12-15

    A high Reynolds number boundary-layer wind-tunnel facility at New Mexico State University was fitted with a regularly distributed braille surface. The surface was such that braille dots were closely packed in the streamwise direction and sparsely spaced in the spanwise direction. This novel surface had an unexpected influence on the flow: the energy of the very large-scale features of wall turbulence (approximately six-times the boundary-layer thickness in length) became significantly attenuated, even into the logarithmic region. To the author's knowledge, this is the first experimental study to report a modification of 'superstructures' in a rough-wall turbulent boundary layer. The result gives rise to the possibility that flow control through very small, passive surface roughness may be possible at high Reynolds numbers, without the prohibitive drag penalty anticipated heretofore. Evidence was also found for the uninhibited existence of the near-wall cycle, well known to smooth-wall-turbulence researchers, in the spanwise space between roughness elements. (orig.)

  15. Reynolds-Averaged Turbulence Model Assessment for a Highly Back-Pressured Isolator Flowfield

    Science.gov (United States)

    Baurle, Robert A.; Middleton, Troy F.; Wilson, L. G.

    2012-01-01

    The use of computational fluid dynamics in scramjet engine component development is widespread in the existing literature. Unfortunately, the quantification of model-form uncertainties is rarely addressed with anything other than sensitivity studies, requiring that the computational results be intimately tied to and calibrated against existing test data. This practice must be replaced with a formal uncertainty quantification process for computational fluid dynamics to play an expanded role in the system design, development, and flight certification process. Due to ground test facility limitations, this expanded role is believed to be a requirement by some in the test and evaluation community if scramjet engines are to be given serious consideration as a viable propulsion device. An effort has been initiated at the NASA Langley Research Center to validate several turbulence closure models used for Reynolds-averaged simulations of scramjet isolator flows. The turbulence models considered were the Menter BSL, Menter SST, Wilcox 1998, Wilcox 2006, and the Gatski-Speziale explicit algebraic Reynolds stress models. The simulations were carried out using the VULCAN computational fluid dynamics package developed at the NASA Langley Research Center. A procedure to quantify the numerical errors was developed to account for discretization errors in the validation process. This procedure utilized the grid convergence index defined by Roache as a bounding estimate for the numerical error. The validation data was collected from a mechanically back-pressured constant area (1 2 inch) isolator model with an isolator entrance Mach number of 2.5. As expected, the model-form uncertainty was substantial for the shock-dominated, massively separated flowfield within the isolator as evidenced by a 6 duct height variation in shock train length depending on the turbulence model employed. Generally speaking, the turbulence models that did not include an explicit stress limiter more closely

  16. Unsteady hydraulic characteristics in pipe with elbow under high Reynolds condition

    Energy Technology Data Exchange (ETDEWEB)

    Ono, A.; Kimura, N.; Kamide, H.; Tobita, A. [Japan Atomic Energy Agency, O-arai, Ibaraki (Japan)

    2011-07-01

    In the design of Japan Sodium-cooled Fast Reactor (JSFR), coolant velocity is beyond 9 m/s in the primary hot leg pipe of 1.27 m diameter. The Reynolds number in the piping reaches 4.2x10{sup 7}. Moreover, a short-elbow (r/D=1.0, r: curvature radius, D: pipe diameter) is adopted in the hot leg pipe in order to achieve compact plant layout and reduce plant construction cost. Therefore, the flow-induced vibration (FIV) arising from the piping geometry may occur in the short-elbow pipe. The FIV is due to the excitation force which is caused by the pressure fluctuation on the wall. The pressure fluctuation on the pipe wall is closely related with the flow fluctuation. In this study, water experiments using two types of 1/8 scaled elbows with different curvature ratio, r/D=1.0 and 1.5 (short-elbow and long-elbow), were conducted in order to investigate the mechanism of velocity and pressure fluctuation in the elbow and its downstream. The experiments were carried out at Re=5.4x10{sup 5} conditions. Measurement of velocity fluctuation and pressure fluctuation in two types of elbows with different curvature revealed that behavior of separation region and the circumferential secondary flow affected the pressure fluctuation on the wall of the elbow greatly. (author)

  17. Technique for forcing high Reynolds number isotropic turbulence in physical space

    Science.gov (United States)

    Palmore, John A.; Desjardins, Olivier

    2018-03-01

    Many common engineering problems involve the study of turbulence interaction with other physical processes. For many such physical processes, solutions are expressed most naturally in physical space, necessitating the use of physical space solutions. For simulating isotropic turbulence in physical space, linear forcing is a commonly used strategy because it produces realistic turbulence in an easy-to-implement formulation. However, the method resolves a smaller range of scales on the same mesh than spectral forcing. We propose an alternative approach for turbulence forcing in physical space that uses the low-pass filtered velocity field as the basis of the forcing term. This method is shown to double the range of scales captured by linear forcing while maintaining the flexibility and low computational cost of the original method. This translates to a 60% increase of the Taylor microscale Reynolds number on the same mesh. An extension is made to scalar mixing wherein a scalar field is forced to have an arbitrarily chosen, constant variance. Filtered linear forcing of the scalar field allows for control over the length scale of scalar injection, which could be important when simulating scalar mixing.

  18. Scaling of Polymer Degradation Rate within a High-Reynolds-Number Turbulent Boundary Layer

    Science.gov (United States)

    Elbing, Brian; Solomon, Michael; Perlin, Marc; Dowling, David; Ceccio, Steven

    2009-11-01

    An experiment conducted at the U.S. Navy's Large Cavitation Channel on a 12.9 m long flat-plate test model produced the first quantitative measurements of polymer molecular weight within a turbulent boundary layer. Testing was conducted at speeds to 20 m/s and downstream distance based Reynolds numbers to 220 million. These results showed that the rate of polymer degradation by scission of the polymer chains increases with increased speed, downstream distance and surface roughness. With the surface fully rough at 20 m/s there was no measureable level of drag reduction at the first measurement location (0.56 m downstream of injection). These results are scaled with the assumption that the rate of degradation is dependent on the polymer residence time in the flow and the local shear rate. A successful collapse of the data within the measurement uncertainty was achieved over a range of flow speed (6.6 to 20 m/s), surface roughness (smooth and fully rough) and downstream distance from injection (0.56 to 9.28 m).

  19. Disturbances to Air-Layer Skin-Friction Drag Reduction at High Reynolds Numbers

    Science.gov (United States)

    Dowling, David; Elbing, Brian; Makiharju, Simo; Wiggins, Andrew; Perlin, Marc; Ceccio, Steven

    2009-11-01

    Skin friction drag on a flat surface may be reduced by more than 80% when a layer of air separates the surface from a flowing liquid compared to when such an air layer is absent. Past large-scale experiments utilizing the US Navy's Large Cavitation Channel and a flat-plate test model 3 m wide and 12.9 m long have demonstrated air layer drag reduction (ALDR) on both smooth and rough surfaces at water flow speeds sufficient to reach downstream-distance-based Reynolds numbers exceeding 100 million. For these experiments, the incoming flow conditions, surface orientation, air injection geometry, and buoyancy forces all favored air layer formation. The results presented here extend this prior work to include the effects that vortex generators and free stream flow unsteadiness have on ALDR to assess its robustness for application to ocean-going ships. Measurements include skin friction, static pressure, airflow rate, video of the flow field downstream of the injector, and profiles of the flowing air-water mixture when the injected air forms bubbles, when it is in transition to an air layer, and when the air layer is fully formed. From these, and the prior measurements, ALDR's viability for full-scale applications is assessed.

  20. The application of cryogenics to high Reynolds number testing in wind tunnels. I - Evolution, theory, and advantages

    Science.gov (United States)

    Kilgore, R. A.; Dress, D. A.

    1984-01-01

    During the time which has passed since the construction of the first wind tunnel in 1870, wind tunnels have been developed to a high degree of sophistication. However, their development has consistently failed to keep pace with the demands placed on them. One of the more serious problems to be found with existing transonic wind tunnels is their inability to test subscale aircraft models at Reynolds numbers sufficiently near full-scale values to ensure the validity of using the wind tunnel data to predict flight characteristics. The Reynolds number capability of a wind tunnel may be increased by a number of different approaches. However, the best solution in terms of model, balance, and model support loads, as well as in terms of capital and operating cost appears to be related to the reduction of the temperature of the test gas to cryogenic temperatures. The present paper has the objective to review the evolution of the cryogenic wind tunnel concept and to describe its more important advantages.

  1. High efficiency cyclotron trap assisted positron moderator

    OpenAIRE

    Gerchow, L.; Cooke, D. A.; Braccini, S.; Döbeli, M.; Kirch, K.; Köster, U.; Müller, A.; Van Der Meulen, N. P.; Vermeulen, C.; Rubbia, A.; Crivelli, P.

    2017-01-01

    We report the realisation of a cyclotron trap assisted positron tungsten moderator for the conversion of positrons with a broad keV- few MeV energy spectrum to a mono-energetic eV beam with an efficiency of 1.8(2)% defined as the ratio of the slow positrons divided by the $\\beta^+$ activity of the radioactive source. This is an improvement of almost two orders of magnitude compared to the state of the art of tungsten moderators. The simulation validated with this measurement suggests that usi...

  2. Direct numerical simulation of combustion at high Reynolds numbers; Direkte Numerische Simulation der Verbrennung bei hoeheren Reynoldszahlen

    Energy Technology Data Exchange (ETDEWEB)

    Frouzakis, C. E.; Boulouchos, K.

    2005-12-15

    This comprehensive illustrated final report for the Swiss Federal Office of Energy (SFOE) reports on the work done at the Swiss Federal Institute of Technology in Zurich on the numerical simulation of combustion processes at high Reynolds numbers. The authors note that with appropriate extensive calculation effort, results can be obtained that demonstrate a high degree of accuracy. It is noted that a large part of the project work was devoted to the development of algorithms for the simulation of the combustion processes. Application work is also discussed with research on combustion stability being carried on. The direct numerical simulation (DNS) methods used are described and co-operation with other institutes is noted. The results of experimental work are compared with those provided by simulation and are discussed in detail. Conclusions and an outlook round off the report.

  3. Drop Characteristics of non-Newtonian Impinging Jets at High Generalized Bird-Carreau Jet Reynolds Numbers

    Science.gov (United States)

    Sojka, Paul E.; Rodrigues, Neil S.

    2015-11-01

    The current study investigates the drop characteristics of three Carboxymethylcellulose (CMC) sprays produced by the impingement of two liquid jets. The three water-based solutions used in this work (0.5 wt.-% CMC-7MF, 0.8 wt.-% CMC-7MF, and 1.4 wt.-% CMC-7MF) exhibited strong shear-thinning, non-Newtonian behavior - characterized by the Bird-Carreau rheological model. A generalized Bird-Carreau jet Reynolds number was used as the primary parameter to characterize the drop size and the drop velocity, which were measured using Phase Doppler Anemometry (PDA). PDA optical configuration enabled a drop size measurement range of approximately 2.3 to 116.2 μm. 50,000 drops were measured at each test condition to ensure statistical significance. The arithmetic mean diameter (D10) , Sauter mean diameter (D32) , and mass median diameter (MMD) were used as representative diameters to characterize drop size. The mean axial drop velocity Uz -mean along with its root-mean square Uz -rms were used to characterize drop velocity. Incredibly, measurements for all three CMC liquids and reference DI water sprays seemed to follow a single curve for D32 and MMD drop diameters in the high generalized Bird-Carreau jet Reynolds number range considered in this work (9.21E +03

  4. Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, M., E-mail: micheline.abbas@ensiacet.fr [Laboratoire de Génie Chimique, Université de Toulouse INPT-UPS, 31030, Toulouse (France); CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Magaud, P. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Gao, Y. [Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Geoffroy, S. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Laboratoire Matériaux et Durabilité des Constructions, Université de Toulouse (France); UPS, INSA, 31077, Toulouse (France)

    2014-12-15

    The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions.

  5. Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

    International Nuclear Information System (INIS)

    Abbas, M.; Magaud, P.; Gao, Y.; Geoffroy, S.

    2014-01-01

    The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions

  6. Mechanism of subcooled water flow boiling critical heat flux in a circular tube at high liquid Reynolds number

    International Nuclear Information System (INIS)

    Hata, K.; Fukuda, K.; Masuzaki, S.

    2014-01-01

    The subcooled boiling heat transfer and the steady state critical heat flux (CHF) in a vertical circular tube for the flow velocities (u=3.95 to 30.80 m/s) are systematically measured by the experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The SUS304 test tube of inner diameter (d=6 mm) and heated length (L=59.5 mm) is used in this work. The outer surface temperatures of the SUS304 test tube with heating are observed by an infrared thermal imaging camera and a video camera. The subcooled boiling heat transfers for SUS304 test tube are compared with the values calculated by other workers' correlations for the subcooled boiling heat transfer. The influence of flow velocity on the subcooled boiling heat transfer and the CHF is investigated into details based on the experimental data. Nucleate boiling surface superheats at the CHF are close to the lower limit of the heterogeneous spontaneous nucleation temperature and the homogeneous spontaneous nucleation temperature. The dominant mechanism of the subcooled flow boiling CHF on the SUS304 circular tube is discussed at high liquid Reynolds number. On the other hand, theoretical equations for k-ε turbulence model in a circular tube of a 3 mm in diameter and a 526 mm long are numerically solved for heating of water on heated section of a 3 mm in diameter and a 67 mm long with various thicknesses of conductive sub-layer by using PHOENICS code under the same conditions as the experimental ones previously obtained considering the temperature dependence of thermo-physical properties concerned. The Platinum (Pt) test tube of inner diameter (d=3 mm) and heated length (L=66.5 mm) was used in this experiment. The thicknesses of conductive sub-layer from non-boiling regime to CHF are clarified. The thicknesses of conductive sub-layer at the CHF point are evaluated for various flow velocities. The experimental values of the CHF are also compared with the corresponding

  7. Direct numerical simulation of MHD heat transfer in high Reynolds number turbulent channel flows for Prandtl number of 25

    International Nuclear Information System (INIS)

    Yamamoto, Yoshinobu; Kunugi, Tomoaki

    2015-01-01

    Graphical abstract: - Highlights: • For the first time, the MHD heat transfer DNS database corresponding to the typical nondimensional parameters of the fusion blanket design using molten salt, were established. • MHD heat transfer correlation was proposed and about 20% of the heat transfer degradation was evaluated under the design conditions. • The contribution of the turbulent diffusion to heat transfer is increased drastically with increasing Hartmann number. - Abstract: The high-Prandtl number passive scalar transport of the turbulent channel flow imposed a wall-normal magnetic field is investigated through the large-scale direct numerical simulation (DNS). All essential turbulence scales of velocities and temperature are resolved by using 2048 × 870 × 1024 computational grid points in stream, vertical, and spanwise directions. The heat transfer phenomena for a Prandtl number of 25 were observed under the following flow conditions: the bulk Reynolds number of 14,000 and Hartman number of up to 28. These values were equivalent to the typical nondimensional parameters of the fusion blanket design proposed by Wong et al. As a result, a high-accuracy DNS database for the verification of magnetohydrodynamic turbulent heat transfer models was established for the first time, and it was confirmed that the heat transfer correlation for a Prandtl number of 5.25 proposed by Yamamoto and Kunugi was applicable to the Prandtl number of 25 used in this study

  8. Direct numerical simulation of MHD heat transfer in high Reynolds number turbulent channel flows for Prandtl number of 25

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yoshinobu, E-mail: yamamotoy@yamanashi.ac.jp [Department of Mechanical Systems Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu 400-8511 (Japan); Kunugi, Tomoaki [Department of Nuclear Engineering, Kyoto University Yoshida, Sakyo, Kyoto 606-8501 (Japan)

    2015-01-15

    Graphical abstract: - Highlights: • For the first time, the MHD heat transfer DNS database corresponding to the typical nondimensional parameters of the fusion blanket design using molten salt, were established. • MHD heat transfer correlation was proposed and about 20% of the heat transfer degradation was evaluated under the design conditions. • The contribution of the turbulent diffusion to heat transfer is increased drastically with increasing Hartmann number. - Abstract: The high-Prandtl number passive scalar transport of the turbulent channel flow imposed a wall-normal magnetic field is investigated through the large-scale direct numerical simulation (DNS). All essential turbulence scales of velocities and temperature are resolved by using 2048 × 870 × 1024 computational grid points in stream, vertical, and spanwise directions. The heat transfer phenomena for a Prandtl number of 25 were observed under the following flow conditions: the bulk Reynolds number of 14,000 and Hartman number of up to 28. These values were equivalent to the typical nondimensional parameters of the fusion blanket design proposed by Wong et al. As a result, a high-accuracy DNS database for the verification of magnetohydrodynamic turbulent heat transfer models was established for the first time, and it was confirmed that the heat transfer correlation for a Prandtl number of 5.25 proposed by Yamamoto and Kunugi was applicable to the Prandtl number of 25 used in this study.

  9. Diffusion of Drag-Reducing Polymers within a High-Reynolds-Number, Rough-Wall Turbulent Boundary Layer

    Science.gov (United States)

    Elbing, Brian; Perlin, Marc; Dowling, David; Solomon, Michael; Ceccio, Steven

    2008-11-01

    Two experiments were conducted to investigate polymer drag reduction (PDR) within high Reynolds number (to 200 million based on downstream distance), rough-wall turbulent boundary layers. The first experiment was conducted at the U.S. Navy's Large Cavitation Channel on a 12.9 m long flat-plate at speeds to 20 m/s with the surface hydraulically smooth and fully rough. Local skin-friction measurements on the smooth and rough surfaces had maximum PDR levels of 65 and 75 percent, respectively. However, PDR decreased with increasing downstream distance and flow speed more rapidly on the rough surface, and at the top speed no measureable level of PDR was observed. The roughness-induced increased diffusion was quantified with near-wall concentration measurements and the second experiment, which measured concentration profiles on a 0.94 m long flat-plate with three surface conditions: smooth, 240-grit, and 60-grit sandpaper. The increased diffusion does not fully explain the smooth-rough PDR differences observed in the first experiment. Rheological analysis of drawn samples from the first experiment indicates that polymer degradation (chain scission) could be responsible for the remaining loss of rough-wall PDR. These results have implications for the cost effectiveness of PDR for surface ships.

  10. Effect of Surface Roughness on Polymer Drag Reduction with a High-Reynolds-Number Turbulent Boundary Layer

    Science.gov (United States)

    Elbing, Brian; Dowling, David; Solomon, Michael; Bian, Sherry; Ceccio, Steven

    2007-11-01

    A recent experiment at the U.S. Navy's Large Cavitation Channel (LCC) investigated the effect of wall roughness on wall-injection polymer drag reduction (PDR) within a high-Reynolds-number (10^7 to 2x10^8 based on downstream distance) turbulent boundary layer (TBL). Testing was performed in two parts: 1) PDR experiment on a 12.9 m long, 3.05 m wide hydro-dynamically smooth flat plate and 2) PDR experiment on the same model with the entire surface roughened. The roughness was produced by blowing glass beads into epoxy paint that was applied to the entire model. The roughened model had an average roughness height ranging between 307 and 1154 μm. Drag reduction was determined using six, stream-wise located integrated skin-friction balances. In addition to skin-friction measurements, sampling was performed at three stream-wise located ports. The sampling ports were used to determine the amount of degradation, if any, caused by the turbulent flow on the polymer. Both the skin-friction measurements and sampling analysis indicates that wall roughness in a turbulent boundary layer significantly increases degradation of the polymer solution.

  11. Length and time scales of the near-surface axial velocity in a high Reynolds number turbulent boundary layer

    International Nuclear Information System (INIS)

    Metzger, M.

    2006-01-01

    Reynolds number effects on relevant length and time scales in the near-wall region of a canonical turbulent boundary layer are investigated. Well resolved measurements in the atmospheric surface layer are compared with existing laboratory data to give a composite Reynolds number range spanning over three orders of magnitude. In the field experiments, a vertical rake of twenty single element hot-wires was used to measure the axial velocity, u, characteristics in the lower log layer region of the atmospheric surface layer that flows over Utah's western desert. Only data acquired under conditions of near-neutral thermal stability are analyzed. The shape of the power spectra of u as a function of distance from the wall, y, and Reynolds number is investigated, with emphasis on the appropriate scaling parameters valid across different wavenumber, k, bands. In particular, distance from the wall is found to scale the region of the u spectra around ky = 1. The presence of a k -1 slope in the spectra is also found to correlate with the Reynolds number dependence in the peak of the root mean square u profile. In addition, Reynolds number trends in the profiles of the Taylor microscales, which represent intermediate length and time scales in the boundary layer, are shown to deviate from classical scaling

  12. Moderate and high intensity pulsed electric fields

    OpenAIRE

    Timmermans, Rian Adriana Hendrika

    2018-01-01

    Pulsed Electric Field (PEF) processing has gained a lot of interest the last decades as mild processing technology as alternative to thermal pasteurisation, and is suitable for preservation of liquid food products such as fruit juices. PEF conditions typically applied at industrial scale for pasteurisation are high intensity pulsed electric fields aiming for minimal heat load, with an electric field strength (E) in the range of 15 − 20 kV/cm and pulse width (τ) between 2 − 20 μs. Alternativel...

  13. High-Reynolds Number Active Blowing Semi-Span Force Measurement System Development

    Science.gov (United States)

    Lynn, Keith C.; Rhew, Ray D.; Acheson, Michael J.; Jones, Gregory S.; Milholen, William E.; Goodliff, Scott L.

    2012-01-01

    Recent wind-tunnel tests at the NASA Langley Research Center National Transonic Facility utilized high-pressure bellows to route air to the model for evaluating aircraft circulation control. The introduction of these bellows within the Sidewall Model Support System significantly impacted the performance of the external sidewall mounted semi-span balance. As a result of this impact on the semi-span balance measurement performance, it became apparent that a new capability needed to be built into the National Transonic Facility s infrastructure to allow for performing pressure tare calibrations on the balance in order to properly characterize its performance under the influence of static bellows pressure tare loads and bellows thermal effects. The objective of this study was to design both mechanical calibration hardware and an experimental calibration design that can be employed at the facility in order to efficiently and precisely perform the necessary loadings in order to characterize the semi-span balance under the influence of multiple calibration factors (balance forces/moments and bellows pressure/temperature). Using statistical design of experiments, an experimental design was developed allowing for strategically characterizing the behavior of the semi-span balance for use in circulation control and propulsion-type flow control testing at the National Transonic Facility.

  14. Large-eddy simulation/Reynolds-averaged Navier-Stokes hybrid schemes for high speed flows

    Science.gov (United States)

    Xiao, Xudong

    Three LES/RANS hybrid schemes have been proposed for the prediction of high speed separated flows. Each method couples the k-zeta (Enstrophy) BANS model with an LES subgrid scale one-equation model by using a blending function that is coordinate system independent. Two of these functions are based on turbulence dissipation length scale and grid size, while the third one has no explicit dependence on the grid. To implement the LES/RANS hybrid schemes, a new rescaling-reintroducing method is used to generate time-dependent turbulent inflow conditions. The hybrid schemes have been tested on a Mach 2.88 flow over 25 degree compression-expansion ramp and a Mach 2.79 flow over 20 degree compression ramp. A special computation procedure has been designed to prevent the separation zone from expanding upstream to the recycle-plane. The code is parallelized using Message Passing Interface (MPI) and is optimized for running on IBM-SP3 parallel machine. The scheme was validated first for a flat plate. It was shown that the blending function has to be monotonic to prevent the RANS region from appearing in the LES region. In the 25 deg ramp case, the hybrid schemes provided better agreement with experiment in the recovery region. Grid refinement studies demonstrated the importance of using a grid independent blend function and further improvement with experiment in the recovery region. In the 20 deg ramp case, with a relatively finer grid, the hybrid scheme characterized by grid independent blending function well predicted the flow field in both the separation region and the recovery region. Therefore, with "appropriately" fine grid, current hybrid schemes are promising for the simulation of shock wave/boundary layer interaction problems.

  15. Drag reduction using wrinkled surfaces in high Reynolds number laminar boundary layer flows

    Science.gov (United States)

    Raayai-Ardakani, Shabnam; McKinley, Gareth H.

    2017-09-01

    Inspired by the design of the ribbed structure of shark skin, passive drag reduction methods using stream-wise riblet surfaces have previously been developed and tested over a wide range of flow conditions. Such textures aligned in the flow direction have been shown to be able to reduce skin friction drag by 4%-8%. Here, we explore the effects of periodic sinusoidal riblet surfaces aligned in the flow direction (also known as a "wrinkled" texture) on the evolution of a laminar boundary layer flow. Using numerical analysis with the open source Computational Fluid Dynamics solver OpenFOAM, boundary layer flow over sinusoidal wrinkled plates with a range of wavelength to plate length ratios ( λ / L ), aspect ratios ( 2 A / λ ), and inlet velocities are examined. It is shown that in the laminar boundary layer regime, the riblets are able to retard the viscous flow inside the grooves creating a cushion of stagnant fluid that the high-speed fluid above can partially slide over, thus reducing the shear stress inside the grooves and the total integrated viscous drag force on the plate. Additionally, we explore how the boundary layer thickness, local average shear stress distribution, and total drag force on the wrinkled plate vary with the aspect ratio of the riblets as well as the length of the plate. We show that riblets with an aspect ratio of close to unity lead to the highest reduction in the total drag, and that because of the interplay between the local stress distribution on the plate and stream-wise evolution of the boundary layer the plate has to exceed a critical length to give a net decrease in the total drag force.

  16. Effects of Reynolds Number on the Energy Conversion and Near-Wake Dynamics of a High Solidity Vertical-Axis Cross-Flow Turbine

    Directory of Open Access Journals (Sweden)

    Peter Bachant

    2016-01-01

    Full Text Available Experiments were performed with a large laboratory-scale high solidity cross-flow turbine to investigate Reynolds number effects on performance and wake characteristics and to establish scale thresholds for physical and numerical modeling of individual devices and arrays. It was demonstrated that the performance of the cross-flow turbine becomes essentially R e -independent at a Reynolds number based on the rotor diameter R e D ≈ 10 6 or an approximate average Reynolds number based on the blade chord length R e c ≈ 2 × 10 5 . A simple model that calculates the peak torque coefficient from static foil data and cross-flow turbine kinematics was shown to be a reasonable predictor for Reynolds number dependence of an actual cross-flow turbine operating under dynamic conditions. Mean velocity and turbulence measurements in the near-wake showed subtle differences over the range of R e investigated. However, when transport terms for the streamwise momentum and mean kinetic energy were calculated, a similar R e threshold was revealed. These results imply that physical model studies of cross-flow turbines should achieve R e D ∼ 10 6 to properly approximate both the performance and wake dynamics of full-scale devices and arrays.

  17. Water Tank Experiments on Stratified Flow over Double Mountain-Shaped Obstacles at High-Reynolds Number

    Directory of Open Access Journals (Sweden)

    Ivana Stiperski

    2017-01-01

    Full Text Available In this article, we present an overview of the HyIV-CNRS-SecORo (Hydralab IV-CNRS-Secondary Orography and Rotors Experiments laboratory experiments carried out in the CNRM (Centre National de Recherches Météorologiques large stratified water flume. The experiments were designed to systematically study the influence of double obstacles on stably stratified flow. The experimental set-up consists of a two-layer flow in the water tank, with a lower neutral and an upper stable layer separated by a sharp density discontinuity. This type of layering over terrain is known to be conducive to a variety of possible responses in the atmosphere, from hydraulic jumps to lee waves and highly turbulent rotors. In each experiment, obstacles were towed through the tank at a constant speed. The towing speed and the size of the tank allowed high Reynolds-number flow similar to the atmosphere. Here, we present the experimental design, together with an overview of laboratory experiments conducted and their results. We develop a regime diagram for flow over single and double obstacles and examine the parameter space where the secondary obstacle has the largest influence on the flow. Trapped lee waves, rotors, hydraulic jumps, lee-wave interference and flushing of the valley atmosphere are successfully reproduced in the stratified water tank. Obstacle height and ridge separation distance are shown to control lee-wave interference. Results, however, differ partially from previous findings on the flow over double ridges reported in the literature due to the presence of nonlinearities and possible differences in the boundary layer structure. The secondary obstacle also influences the transition between different flow regimes and makes trapped lee waves possible for higher Froude numbers than expected for an isolated obstacle.

  18. Heat transfer in an axisymmetric stagnation flow at high Reynolds numbers on a cylinder using perturbation techniques

    International Nuclear Information System (INIS)

    Rahimi, A. B.

    2003-01-01

    Although there are many papers on the subject of heat transfer in an axisymmetric stagnation flow on a cylinder, the available knowledge is mainly for low Reynolds numbers and not much information exists for the same problem at large Reynolds numbers. In this work, the problem of heat transfer in an axisymmetric stagnation flow on a cylinder is solved at large Reynolds numbers using perturbation techniques. Starting from Navier-Stokes equations within a boundary layer approximation and using similarity transformations, the governing equations are obtained in the form of differential equations. The inverse of the Reynolds number is introduced as the perturbation parameter. This parameter appears in front of the highest-order terms and, as it tends to zero, reduces the order of the governing equations and produces singularities. In this paper, the flow field is divided into two regions; rapid changes in the region near wall and slow changes away from the wall. Thus, the flow is found to have dual-layer characteristics. Using inner and outer expansion produces uniform values of the relevant quantities

  19. Development of zirconium hydride highly effective moderator materials

    International Nuclear Information System (INIS)

    Yin Changgeng

    2005-10-01

    The zirconium hydride with highly content of hydrogen and low density is new efficient moderator material for space nuclear power reactor. Russia has researched it to use as new highly moderator and radiation protection materials. Japanese has located it between the top of pressure vessel and the main protection as a shelter, the work temperature is rach to 220 degree C. The zirconium hydride moderator blocks are main parts of space nuclear power reactor. Development of zirconium hydride moderator materials have strength research and apply value. Nuclear Power Research and Design Instituteoh China (NPIC) has sep up the hydrogenation device and inspect systems, and accumurate a large of experience about zirconium hydride, also set up a strict system of QA and QC. (authors)

  20. Longitudinal Aerodynamic Characteristics and Wing Pressure Distributions of a Blended-Wing-Body Configuration at Low and High Reynolds Numbers

    Science.gov (United States)

    Re, Richard J.

    2005-01-01

    Force balance and wing pressure data were obtained on a 0.017-Scale Model of a blended-wing-body configuration (without a simulated propulsion system installation) to validate the capability of computational fluid dynamic codes to predict the performance of such thick sectioned subsonic transport configurations. The tests were conducted in the National Transonic Facility of the Langley Research Center at Reynolds numbers from 3.5 to 25.0 million at Mach numbers from 0.25 to 0.86. Data were obtained in the pitch plane only at angles of attack from -1 to 8 deg at Mach numbers greater than 0.25. A configuration with winglets was tested at a Reynolds number of 25.0 million at Mach numbers from 0.83 to 0.86.

  1. Moderate-to-high intensity aerobic exercise in patients with mild to moderate Alzheimer's disease

    DEFF Research Database (Denmark)

    Frederiksen, Kristian S; Sobol, Nanna; Beyer, Nina

    2014-01-01

    OBJECTIVES: Physical exercise may modulate neuropathology and symptoms of Alzheimer's disease (AD). This pilot study assessed the feasibility of conducting a study of moderate-to-high intensity aerobic exercise in home-dwelling patients with mild AD. METHODS: An uncontrolled preintervention......-postintervention test design with a single group receiving the same intervention. A total of eight patients with mild to moderate AD from the Copenhagen Memory clinic were included in the study. The intervention lasted for 14 weeks and consisted of supervised, 1-h sessions of aerobic exercise three times per week (50......-60% of heart rate reserve for a two-week adaptation period and 70-80 % of heart rate reserve for the remaining 12 weeks) Feasibility was assessed based on acceptability, including attendance and drop-out, safety, and patients' and caregivers' attitudes towards the intervention as well as other relevant...

  2. Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows

    Science.gov (United States)

    Sammy, Mo

    2010-01-01

    Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).

  3. RANS / LES coupling applied to high Reynolds number turbulent flows of the nuclear industry; Application du couplage RANS / LES aux ecoulements turbulents a haut nombre de Reynolds de l'industrie nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Benarafa, Y

    2005-12-15

    The main issue to perform a computational study of high Reynolds numbered turbulent flows consists on predicting their unsteadiness without implying a tremendous computational cost. First, the main drawbacks of large-eddy simulation with standard wall model on a coarse mesh for a plane channel flow are highlighted. To correct these drawbacks two coupling RANS/LES methods have been proposed. The first one relies on a sophisticated wall model (TBLE) which consists on solving Thin Boundary Layer Equations with a RANS type turbulent closure in the near wall region. The second one consists on a RANS/LES methods have been proposed. The second one consists on a RANS/LES coupling method using a forcing term approach. These various approaches have been implemented in the TRIO-U code developed at CEA (French Atomic Center) at Grenoble, France. The studied flow configurations are the fully developed plane channel flow and a flow around a surface-mounted cubical obstacle. Both approaches provide encouraging results and allow a surface-mounted cubical obstacle. Both approaches provide encouraging results and allow unsteady simulations for a low computational cost. (author)

  4. Modeling of high speed micro rotors in moderate flow confinement

    NARCIS (Netherlands)

    Dikmen, E.; van der Hoogt, Peter; Aarts, Ronald G.K.M.; Sas, P.; Bergen, B.

    2008-01-01

    The recent developments in high speed micro rotating machinery lead to the need for multiphysical modeling of the rotor and the surrounding medium. In this study, thermal and flow induced effects on rotor dynamics of geometries with moderate flow confinement are studied. The structure is modeled via

  5. Aerodynamic Effects of High Turbulence Intensity on a Variable-Speed Power-Turbine Blade With Large Incidence and Reynolds Number Variations

    Science.gov (United States)

    Flegel, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2014-01-01

    The effects of high inlet turbulence intensity on the aerodynamic performance of a variable speed power turbine blade are examined over large incidence and Reynolds number ranges. These results are compared to previous measurements made in a low turbulence environment. Both high and low turbulence studies were conducted in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility. The purpose of the low inlet turbulence study was to examine the transitional flow effects that are anticipated at cruise Reynolds numbers. The current study extends this to LPT-relevant turbulence levels while perhaps sacrificing transitional flow effects. Assessing the effects of turbulence at these large incidence and Reynolds number variations complements the existing database. Downstream total pressure and exit angle data were acquired for 10 incidence angles ranging from +15.8deg to -51.0deg. For each incidence angle, data were obtained at five flow conditions with the exit Reynolds number ranging from 2.12×10(exp 5) to 2.12×10(exp 6) and at a design exit Mach number of 0.72. In order to achieve the lowest Reynolds number, the exit Mach number was reduced to 0.35 due to facility constraints. The inlet turbulence intensity, Tu, was measured using a single-wire hotwire located 0.415 axial-chord upstream of the blade row. The inlet turbulence levels ranged from 8 to 15 percent for the current study. Tu measurements were also made farther upstream so that turbulence decay rates could be calculated as needed for computational inlet boundary conditions. Downstream flow field measurements were obtained using a pneumatic five-hole pitch/yaw probe located in a survey plane 7 percent axial chord aft of the blade trailing edge and covering three blade passages. Blade and endwall static pressures were acquired for each flow condition as well. The blade loading data show that the suction surface separation that was evident at many of the low Tu conditions has been eliminated. At

  6. The high moderating ratio reactor using 100% MOX reloads

    International Nuclear Information System (INIS)

    Barbrault, P.

    1994-06-01

    This report presents the concept of a High Moderating ratio Reactor, which should accept 100% MOX reloads. This reactor aims to be the plutonium version of the European Pressurized Reactor (EPR), which is developed jointly by French and German companies. A moderating ration of 2.5 (instead of the standard value of 2.0) is obtained by replacing several fuel rods by water holes. The core would contain 241 Fuel Assemblies. We present some advantages of over-moderation for plutonium fuel, a description of the core and assemblies, calculations of fuel reload schemes and Reactivity Shutdown Margins, and the behavior of the core during two occidental transients. (author). 2 refs., 9 figs., 2 tabs

  7. Development of Localized Arc Filament RF Plasma Actuators for High-Speed and High Reynolds Number Flow Control

    Science.gov (United States)

    2010-01-01

    high-speed flows is problematic due to their low forcing frequency (for mechanical actuators) and low forcing amplitude (for piezo actuators...very low fraction of DC power is coupled to the actuators (5-10%), with the rest of the power dissipated in massive ballast resistors acting as heat... resistors . The use of high-power resistors also significantly increases the weight and size of the plasma generator and makes scaling to a large number of

  8. Moderate energy ions for high energy density physics experiments

    International Nuclear Information System (INIS)

    Grisham, L.R.

    2004-01-01

    This paper gives the results of a preliminary exploration of whether moderate energy ions (≅0.3-3 MeV/amu) could be useful as modest-cost drivers for high energy density physics experiments. It is found that if the target thickness is chosen so that the ion beam enters and then leaves the target in the vicinity of the peak of the dE/dX (stopping power) curve, high uniformity of energy deposition may be achievable while also maximizing the amount of energy per beam particle deposited within the target

  9. Low Reynolds Number Vehicles

    Science.gov (United States)

    1985-02-01

    of the blade. The Darrieus VAWT has more complex aerodynamics. This type of wind turbine produces power as a result of the tangential thrust as...Horizontal Axis Propeller-Type b) Verticle Axis Darrieus -Type Figure 78. Wind Turbine Configurations 0 6 Q K [_ 2 -, C 4 UJ UJ...Sailplanes 23 5.2 Wind Turbines 23 6. CONCLUDING REMARKS 24 7. RECOMMENDATIONS FOR FUTURE RESEARCH 24 REFERENCES 25 FIGURES 32 yv/ LOW REYNOLDS NUMBER

  10. The use of low-radius circular-cross-section helical strakes for the reduction of VIV of tapered cylinders at high Reynolds numbers

    DEFF Research Database (Denmark)

    Johansson, Jens; Christensen, Silas Sverre

    2018-01-01

    % for strakes of circular cross section. The present paper argues that this height can be reduced for structures where the critical wind velocity for vortex shedding is in the Supercritical Reynolds number regime. The investigations are aimed for suppressing VIV on offshore wind turbine towers during......^5, i.e. in the Supercritical Reynolds number regime. Results indicate that circular strakes with a diameter corresponding to 3% of the mean diameter of the structure can be used to efficiently reduce VIV at Supercritical Reynolds numbers. This suggests that e.g. robes may be used as temporary helical...

  11. Higher-order differencing method with a multigrid approach for the solution of the incompressible flow equations at high Reynolds numbers

    International Nuclear Information System (INIS)

    Tzanos, C.P.

    1992-01-01

    A higher-order differencing method was recently proposed for the convection-diffusion equation, which even with a coarse mesh gives oscillation-free solutions that are far more accurate than those of the upwind scheme. In this paper, the performance of this method is investigated in conjunction with the performance of different iterative solvers for the solution of the Navier-Stokes equations in the vorticity-streamfunction formulation for incompressible flow at high Reynolds numbers. Flow in a square cavity with a moving lid was chosen as a model problem. Solvers that performed well at low Re numbers either failed to converge or had a computationally prohibitive convergence rate at high Re numbers. The additive correction method of Settari and Aziz and an iterative incomplete lower and upper (ILU) solver were used in a multigrid approach that performed well in the whole range of Re numbers considered (from 1000 to 10,000) and for uniform as well as nonuniform grids. At high Re numbers, point or line Gauss-Seidel solvers converged with uniform grids, but failed to converge with nonuniform grids

  12. Only minor additional metabolic health benefits of high as opposed to moderate dose physical exercise in young, moderately overweight men.

    Science.gov (United States)

    Reichkendler, M H; Rosenkilde, M; Auerbach, P L; Agerschou, J; Nielsen, M B; Kjaer, A; Hoejgaard, L; Sjödin, A; Ploug, T; Stallknecht, B

    2014-05-01

    The dose-response effects of exercise training on insulin sensitivity, metabolic risk, and quality of life were examined. Sixty-one healthy, sedentary (VO₂max: 35 ± 5 ml/kg/min), moderately overweight (BMI: 27.9 ± 1.8), young (age: 29 ± 6 years) men were randomized to sedentary living (sedentary control group; n = 18), moderate (moderate dose training group [MOD]: 300 kcal/day, n = 21), or high (high dose training group [HIGH]: 600 kcal/day, n = 22) dose physical exercise for 11 weeks. The return rate for post-intervention testing was 82-94% across groups. Weekly exercise amounted to 2,004 ± 24 and 3,774 ± 68 kcal, respectively, in MOD and HIGH. Cardiorespiratory fitness increased (P exercise groups (MOD: 32 ± 1 to 29 ± 1%; HIGH: 30 ± 1 to 27 ± 1%). Peripheral insulin sensitivity increased (P benefits were found when exercising ∼3,800 as opposed to ∼2,000 kcal/week in young moderately overweight men. This finding may have important public health implications. Copyright © 2012 The Obesity Society.

  13. Only minor additional metabolic health benefits of high as opposed to moderate dose physical exercise in young, moderately overweight men

    DEFF Research Database (Denmark)

    Reichkendler, M H; Larsen, Mads Rosenkilde; Auerbach, P L

    2014-01-01

    % in HIGH (P health assessed by questionnaire increased similarly in MOD (P additional health benefits were found when exercising ∼3,800 as opposed to ∼2,000 kcal/week in young moderately overweight men. This finding may have important...... public health implications....

  14. Enhancements to the FAST-MAC Circulation Control Model and Recent High-Reynolds Number Testing in the National Transonic Facility

    Science.gov (United States)

    Milholen, William E., II; Jones, Gregory S.; Chan, David T.; Goodliff, Scott L.; Anders, Scott G.; Melton, Latunia P.; Carter, Melissa B.; Allan, Brian G.; Capone, Francis J.

    2013-01-01

    A second wind tunnel test of the FAST-MAC circulation control model was recently completed in the National Transonic Facility at the NASA Langley Research Center. The model was equipped with four onboard flow control valves allowing independent control of the circulation control plenums, which were directed over a 15% chord simple-hinged flap. The model was configured for low-speed high-lift testing with flap deflections of 30 and 60 degrees, along with the transonic cruise configuration with zero degree flap deflection. Testing was again conducted over a wide range of Mach numbers up to 0.88, and Reynolds numbers up to 30 million based on the mean chord. The first wind tunnel test had poor transonic force and moment data repeatability at mild cryogenic conditions due to inadequate thermal conditioning of the balance. The second test demonstrated that an improvement to the balance heating system significantly improved the transonic data repeatability, but also indicated further improvements are still needed. The low-speed highlift performance of the model was improved by testing various blowing slot heights, and the circulation control was again demonstrated to be effective in re-attaching the flow over the wing at off-design transonic conditions. A new tailored spanwise blowing technique was also demonstrated to be effective at transonic conditions with the benefit of reduced mass flow requirements.

  15. A nested-LES wall-modeling approach for computation of high Reynolds number equilibrium and non-equilibrium wall-bounded turbulent flows

    Science.gov (United States)

    Tang, Yifeng; Akhavan, Rayhaneh

    2014-11-01

    A nested-LES wall-modeling approach for high Reynolds number, wall-bounded turbulence is presented. In this approach, a coarse-grained LES is performed in the full-domain, along with a nested, fine-resolution LES in a minimal flow unit. The coupling between the two domains is achieved by renormalizing the instantaneous LES velocity fields to match the profiles of kinetic energies of components of the mean velocity and velocity fluctuations in both domains to those of the minimal flow unit in the near-wall region, and to those of the full-domain in the outer region. The method is of fixed computational cost, independent of Reτ , in homogenous flows, and is O (Reτ) in strongly non-homogenous flows. The method has been applied to equilibrium turbulent channel flows at 1000 shear-driven, 3D turbulent channel flow at Reτ ~ 2000 . In equilibrium channel flow, the friction coefficient and the one-point turbulence statistics are predicted in agreement with Dean's correlation and available DNS and experimental data. In shear-driven, 3D channel flow, the evolution of turbulence statistics is predicted in agreement with experimental data of Driver & Hebbar (1991) in shear-driven, 3D boundary layer flow.

  16. CHF considerations for highly moderated 100% MOX fuels PWRs

    Energy Technology Data Exchange (ETDEWEB)

    Saphier, D.; Raymond, P. [CEA Saclay, DMT/SERMA/LETR, Gif-sur-Yvette (France)

    1995-09-01

    A feasibility study on using 100% MOX fuel in a PWR with increased moderating ratio, RMA, was initiated. In the proposed design all the parameters were chosen identical to the French 1450MW PWR, except the fuel pin diameter which was reduced to achieve higher moderating ratios, V{sub M}/V{sub F}, where V{sub M} and V{sub F} are the moderator and fuel volume respectively. Moderating ratios from 2 to 4 were considered. In the present study the thermal-hydraulic feasibility of using fuel assemblies with smaller diameter fuel pins was investigated. The major design constrain in this study was the critical heat flux (CHF). In order to maintain the fuel pin integrity under nominal operating and transient conditions, the minimum DNBR, (Departure from Nucleate Boiling Ratio given by CHF/q{close_quotes}{sub local}, where q{close_quotes}{sub local} is the local heat flux), has to be above a given value. The limitations of the existing CHF correlations for the present study are outlined. Two designs based on the conventional 17x17 fuel assembly and on the advanced 19x19 assembly meeting the MDNBR criteria and satisfying the control margin requirements, are proposed.

  17. Rheosensing by impulsive cells at intermediate Reynolds numbers

    Science.gov (United States)

    Mathijssen, Arnold; Bhamla, Saad; Prakash, Manu

    2017-11-01

    For aquatic organisms, mechanical signals are often carried by the surrounding liquid, through viscous and inertial forces. Here we consider a unicellular yet millimetric ciliate, Spirostomum ambiguum, as a model organism to study hydrodynamic sensing. This protist typically swims at moderate Reynolds numbers, Re 100 during impulsive contractions where its elongated body recoils within milliseconds. First, using high-speed PIV and an electrophysiology setup, we deliver controlled voltage pulses to induce these rapid contractions and visualise the vortex flows generated thereby. By comparing these measurements with CFD simulations the range of these hydrodynamic ``signals'' is characterized. Second, we probe the mechano-sensing of the organism with externally applied flows and find a critical shear rate necessary to trigger a contraction. The combination of high Re flow generation and rheosensing could facilitate intercellular communication over large distances. Please also see our other talk ``Collective hydrodynamic communication through ultra-fast contractions''.

  18. Probing the positron moderation process using high-intensity, highly polarized slow-positron beams

    Science.gov (United States)

    Van House, J.; Zitzewitz, P. W.

    1984-01-01

    A highly polarized (P = 0.48 + or - 0.02) intense (500,000/sec) beam of 'slow' (Delta E = about 2 eV) positrons (e+) is generated, and it is shown that it is possible to achieve polarization as high as P = 0.69 + or - 0.04 with reduced intensity. The measured polarization of the slow e+ emitted by five different positron moderators showed no dependence on the moderator atomic number (Z). It is concluded that only source positrons with final kinetic energy below 17 keV contribute to the slow-e+ beam, in disagreement with recent yield functions derived from low-energy measurements. Measurements of polarization and yield with absorbers of different Z between the source and moderator show the effects of the energy and angular distributions of the source positrons on P. The depolarization of fast e+ transmitted through high-Z absorbers has been measured. Applications of polarized slow-e+ beams are discussed.

  19. Conjoint moderate or high-risk alcohol and tobacco use among ...

    African Journals Online (AJOL)

    2016-03-22

    Mar 22, 2016 ... southern Thailand 90.5% were moderate or high-risk tobacco users and 44.6% were moderate or high-risk alcohol users.3 Among general hospital patients in Brazil the rate of comorbidity between alcohol use disorder and nicotine dependence was 3.6%;4 in primary health care TB patients in. South Africa ...

  20. Transonic high Reynolds number stability and control characteristics of a 0.015-scale remotely controlled elevon model (44-0) of the space shuttle orbiter tested in calspan 8-foot TWT (LA70)

    Science.gov (United States)

    Parrell, H.; Gamble, J. D.

    1977-01-01

    Transonic Wind Tunnel tests were run on a .015 scale model of the space shuttle orbiter vehicle in the 8-foot transonic wind tunnel. Purpose of the test program was to obtain basic shuttle aerodynamic data through a full range of elevon and aileron deflections, verification of data obtained at other facilities, and effects of Reynolds number. Tests were performed at Mach numbers from .35 to 1.20 and Reynolds numbers from 3,500,000 to 8,200,000 per foot. The high Reynolds number conditions (nominal 8,000,000/foot) were obtained using the ejector augmentation system. Angle of attack was varied from -2 to +20 degrees at sideslip angles of -2, 0, and +2 degrees. Sideslip was varied from -6 to +8 degrees at constant angles of attack from 0 to +20 degrees. Aileron settings were varied from -5 to +10 degrees at elevon deflections of -10, 0, and +10 degrees. Fixed aileron settings of 0 and 2 degrees in combination with various fixed elevon settings between -20 and +5 degrees were also run at varying angles of attack.

  1. Spatial distribution of moderated neutrons along a Pb target irradiated by high-energy protons

    International Nuclear Information System (INIS)

    Fragopoulou, M.; Manolopoulou, M.; Stoulos, S.; Brandt, R.; Westmeier, W.; Kulakov, B.A.; Krivopustov, M.I.; Sosnin, A.N.; Debeauvais, M.; Adloff, J.C.; Zamani Valasiadou, M.

    2006-01-01

    High-energy protons in the range of 0.5-7.4 GeV have irradiated an extended Pb target covered with a paraffin moderator. The moderator was used in order to shift the hard Pb spallation neutron spectrum to lower energies and to increase the transmutation efficiency via (n,γ) reactions. Neutron distributions along and inside the paraffin moderator were measured. An analysis of the experimental results was performed based on particle production by high-energy interactions with heavy targets and neutron spectrum shifting by the paraffin. Conclusions about the spallation neutron production in the target and moderation through the paraffin are presented. The study of the total neutron fluence on the moderator surface as a function of the proton beam energy shows that neutron cost is improved up to 1 GeV. For higher proton beam energies it remains constant with a tendency to decline

  2. Resonance charge exchange mechanism at high and moderate energies

    International Nuclear Information System (INIS)

    Bogdanov, A.V.; Gevorkyan, A.S.

    1984-01-01

    Charge exchange mechanisms at high and medium energies are investigated, ta king the resonance charge exchange of a proton by an hydrogen atom as an example . It is established that there are two classical charge exchange mechanisms rel ated to direct proton knockout from the bound state and one quantum-mechanical mechanism corresponding to the electron tunnelling from one bound state to anoth er. The classical cross-section diverges for two of these mechanisms, and the quasiclassical scattering amplitude must be calculated on the base of a complex classical trajectory. Physical grounds for the choice of such trajectories are discussed and calculations of the Van Vleck determinant for these mechanisms a re presented. Contributions from different mechanisms to the total charge excha nge cross-section are analyzed. A comparison with experimental data and results of other authors is made

  3. Moderate doses of alcoholic beverages with dinner and postprandial high density lipoprotein composition

    NARCIS (Netherlands)

    Hendriks, H.F.J.; Veenstra, J.; Tol, A. van; Groener, J.E.M.; Schaafsma, G.

    1998-01-01

    Moderate alcohol consumption is associated with a reduced risk of coronary heart disease. In this study, postprandial changes in plasma lipids, high-density lipoprotein (HDL) composition and cholesteryl ester transfer protein (CETP) and lecithin: cholesterol acyltransferase (LCAT) activity levels

  4. Sharp or broad pulse peak for high resolution instruments? Choice of moderator performance

    International Nuclear Information System (INIS)

    Arai, M.; Watanabe, N.; Teshigawara, M.

    2001-01-01

    We demonstrate a concept how we should choose moderator performance to realize required performance for instruments. Neutron burst pulse can be characterized with peak intensity, peak width and tail. Those can be controllable by designing moderator, i.e. material, temperature, shape, decoupling, poisoning and having premoderator. Hence there are large number of variable parameters to be determined. Here we discuss the required moderator performance for some typical examples, i.e. high resolution powder instrument, chopper instrument, high resolution back scattering machine. (author)

  5. Numerical investigation of the vortex-induced vibration of an elastically mounted circular cylinder at high Reynolds number (Re = 104 and low mass ratio using the RANS code.

    Directory of Open Access Journals (Sweden)

    Niaz Bahadur Khan

    Full Text Available This study numerically investigates the vortex-induced vibration (VIV of an elastically mounted rigid cylinder by using Reynolds-averaged Navier-Stokes (RANS equations with computational fluid dynamic (CFD tools. CFD analysis is performed for a fixed-cylinder case with Reynolds number (Re = 104 and for a cylinder that is free to oscillate in the transverse direction and possesses a low mass-damping ratio and Re = 104. Previously, similar studies have been performed with 3-dimensional and comparatively expensive turbulent models. In the current study, the capability and accuracy of the RANS model are validated, and the results of this model are compared with those of detached eddy simulation, direct numerical simulation, and large eddy simulation models. All three response branches and the maximum amplitude are well captured. The 2-dimensional case with the RANS shear-stress transport k-w model, which involves minimal computational cost, is reliable and appropriate for analyzing the characteristics of VIV.

  6. The Influence of Realistic Reynolds Numbers on Slat Noise Simulations

    Science.gov (United States)

    Lockard, David P.; Choudhari, Meelan M.

    2012-01-01

    The slat noise from the 30P/30N high-lift system has been computed using a computational fluid dynamics code in conjunction with a Ffowcs Williams-Hawkings solver. Varying the Reynolds number from 1.71 to 12.0 million based on the stowed chord resulted in slight changes in the radiated noise. Tonal features in the spectra were robust and evident for all Reynolds numbers and even when a spanwise flow was imposed. The general trends observed in near-field fluctuations were also similar for all the different Reynolds numbers. Experiments on simplified, subscale high-lift systems have exhibited noticeable dependencies on the Reynolds number and tripping, although primarily for tonal features rather than the broadband portion of the spectra. Either the 30P/30N model behaves differently, or the computational model is unable to capture these effects. Hence, the results underscore the need for more detailed measurements of the slat cove flow.

  7. Reynolds Metals Company, Massena, NY

    Science.gov (United States)

    The 1,600-acre former Reynolds Metals Facility is located on the St. Lawrence River, approximately eight miles east of the Village of Massena, New York. The facility, which was constructed in 1958 for the production of aluminum, closed in 2014. It is owned

  8. Determination of mean pressure from PIV in compressible flows using the Reynolds-averaging approach

    Science.gov (United States)

    van Gent, Paul L.; van Oudheusden, Bas W.; Schrijer, Ferry F. J.

    2018-03-01

    The feasibility of computing the flow pressure on the basis of PIV velocity data has been demonstrated abundantly for low-speed conditions. The added complications occurring for high-speed compressible flows have, however, so far proved to be largely inhibitive for the accurate experimental determination of instantaneous pressure. Obtaining mean pressure may remain a worthwhile and realistic goal to pursue. In a previous study, a Reynolds-averaging procedure was developed for this, under the moderate-Mach-number assumption that density fluctuations can be neglected. The present communication addresses the accuracy of this assumption, and the consistency of its implementation, by evaluating of the relevance of the different contributions resulting from the Reynolds-averaging. The methodology involves a theoretical order-of-magnitude analysis, complemented with a quantitative assessment based on a simulated and a real PIV experiment. The assessments show that it is sufficient to account for spatial variations in the mean velocity and the Reynolds-stresses and that temporal and spatial density variations (fluctuations and gradients) are of secondary importance and comparable order-of-magnitude. This result permits to simplify the calculation of mean pressure from PIV velocity data and to validate the approximation of neglecting temporal and spatial density variations without having access to reference pressure data.

  9. High moderation MOX cores for effective use of plutonium in LWRs

    International Nuclear Information System (INIS)

    Hamamoto, Kazuko; Kanagawa, Takashi; Hiraiwa, Koji; Sakurada, Koichi; Moriwaki, Masanao; Aoyama, Motoo; Yamamoto, Toru; Ueji, Masao

    2001-01-01

    Conceptual design studies have been performed for high moderation full MOX cores aiming at increasing fissile Pu consumption rate (ratio of the consumed to the loaded fissile Pu) and reducing residual Pu in discharged MOX fuel. The BWR cores studied have hydrogen to heavy metal ratio(H/HM) of 5.9 with increasing water rods and 7.0 with reducing a fuel rod diameter based on a reference 9x9 fuel (H/HM=4.9) of ABWR. The PWR cores studied have H/HM of 5.0 and 6.0 with reducing a fuel rod diameter based on a reference 17x17 fuel (H/HM=4.0) of APWR. Equilibrium core design and plant safety analyses showed that those high moderation cores have compatibility with ABWR and APWR. The fissile Pu consumption rate is 22% larger than the full MOX cores with reference fuel of ABWR and 50% for APWR. The core performance and compatibility has been also evaluated in the condition of multi-recycle of Pu in these high moderation cores. Study has been conducted to evaluate the effect of introducing these high moderation cores in the fuel cycle of Japan. It shows that the high moderation cores produce 26% more cumulative electricity and reduce 22% stock of the fissile Pu by 2050 than the reference cores. (author)

  10. Flow boiling heat transfer at low liquid Reynolds number

    International Nuclear Information System (INIS)

    Weizhong Zhang; Takashi Hibiki; Kaichiro Mishima

    2005-01-01

    Full text of publication follows: In view of the significance of a heat transfer correlation of flow boiling at conditions of low liquid Reynolds number or liquid laminar flow, and very few existing correlations in principle suitable for such flow conditions, this study is aiming at developing a heat transfer correlation of flow boiling at low liquid Reynolds number conditions. The obtained results are as follows: 1. A new heat transfer correlation has been developed for saturated flow boiling at low liquid Reynolds number conditions based on superimposition of two boiling mechanisms, namely convective boiling and nucleate boiling. In the new correlation, two terms corresponding to the mechanisms of nucleate boiling and convective boiling are obtained from the pool boiling correlation by Forster and Zuber and the analytical annular flow model by Hewitt and Hall-Taylor, respectively. 2. An extensive database was collected for saturated flow boiling heat transfer at low liquid Reynolds number conditions, including data for different channels geometries (circular and rectangular), flow orientations (vertical and horizontal), and working fluids (water, R11, R12, R113). 3. An extensive comparison of the new correlation with the collected database shows that the new correlation works satisfactorily with the mean deviation of 16.6% for saturated flow boiling at low liquid Reynolds number conditions. 4. The detailed discussion reveals the similarity of the newly developed correlation for flow boiling at low liquid Reynolds number to the Chen correlation for flow boiling at high liquid Reynolds number. The Reynolds number factor F can be analytically deduced in this study. (authors)

  11. A serach for moderate- and high-energy neturino emission correlated with gamma-ray bursts

    Science.gov (United States)

    Becker-Szendy, R.; Bratton, C. B.; Breault, J.; Casper, D.; Dye, S. T.; Gajewski, W.; Goldhaber, M.; Haines, T. J.; Halverson, P. G.; Kielczewska, D.

    1995-01-01

    A temporal correlation analysis between moderate- (60 Mev less than or equal to E(sub nu)greater than or equal to 2500 MeV) and high-energy (E(sub nu) greater than or equal to 2000 MeV) neutrino interactions consist of two types: the moderate-energy interactions that are contained within the volume of IMB-3 and the upward-going muons produced by high-energy nu(sub mu) interactions in the rock around the detector. No evidence is found for moderate- or high-energy neutrino emission from GRBs nor for any neutrino/neutrino correlation. The nonobservation of nu/GRB correlations allows upper limits to be placed on the neutrino flux associated with GRBs.

  12. Aerodynamics of wings at low Reynolds numbers: Boundary layer separation and reattachment

    Science.gov (United States)

    McArthur, John

    Due to advances in electronics technology, it is now possible to build small scale flying and swimming vehicles. These vehicles will have size and velocity scales similar to small birds and fish, and their characteristic Reynolds number will be between 104 and 105. Currently, these flying and swimming vehicles do not perform well, and very little research has been done to characterize them, or to explain why they perform so poorly. This dissertation documents three basic investigations into the performance of small scale lifting surfaces, with Reynolds numbers near 104. Part I. Low Reynolds number aerodynamics. Three airfoil shapes were studied at Reynolds numbers of 1 and 2x104: a flat plate airfoil, a circular arc cambered airfoil, and the Eppler 387 airfoil. Lift and drag force measurements were made on both 2D and 3D conditions, with the 3D wings having an aspect ratio of 6, and the 2D condition being approximated by placing end plates at the wing tips. Comparisons to the limited number of previous measurements show adequate agreement. Previous studies have been inconclusive on whether lifting line theory can be applied to this range of Re, but this study shows that lifting line theory can be applied when there are no sudden changes in the slope of the force curves. This is highly dependent on the airfoil shape of the wing, and explains why previous studies have been inconclusive. Part II. The laminar separation bubble. The Eppler 387 airfoil was studied at two higher Reynolds numbers: 3 and 6x10 4. Previous studies at a Reynolds number of 6x104 had shown this airfoil experiences a drag increase at moderate lift, and a subsequent drag decrease at high lift. Previous studies suggested that the drag increase is caused by a laminar separation bubble, but the experiments used to show this were conducted at higher Reynolds numbers and extrapolated down. Force measurements were combined with flow field measurements at Reynolds numbers 3 and 6x104 to determine whether

  13. Moderate High Fat Diet Increases Sucrose Self-Administration In Young Rats

    OpenAIRE

    Figlewicz, Dianne P.; Jay, Jennifer L.; Acheson, Molly A.; Magrisso, Irwin J.; West, Constance H.; Zavosh, Aryana; Benoit, Stephen C.; Davis, Jon F.

    2012-01-01

    We have previously reported that a moderately high fat diet increases motivation for sucrose in adult rats. In this study, we tested the motivational, neurochemical, and metabolic effects of the high fat diet in male rats transitioning through puberty, during 5-8 weeks of age. We observed that the high fat diet increased motivated responding for sucrose, which was independent of either metabolic changes or changes in catecholamine neurotransmitter metabolites in the nucleus accumbens. However...

  14. Small-incision lenticule extraction for moderate to high myopia

    DEFF Research Database (Denmark)

    Vestergaard, Anders Højslet; Ivarsen, Anders R; Asp, Sven

    2012-01-01

    Purpose: To present our initial clinical experience with ReLEx® smile for treatment of moderate to high myopia. Setting: Department of Ophthalmology, Aarhus University Hospital. Design: Prospective clinical study. Methods: In ReLEx smile an intrastromal lenticule is cut by a femtosecond laser and...... of ReLEx smile, ReLEx flex, and FS-LASIK....

  15. Moderate-to-high intensity physical exercise in patients with Alzheimer’s disease

    DEFF Research Database (Denmark)

    Hoffmann, Kristine; Sobol, Nanna A.; Frederiksen, Kristian S.

    2016-01-01

    Background: Studies of physical exercise in patients with Alzheimer’s disease (AD) are few and results have been inconsistent. Objective: To assess the effects of a moderate-to-high intensity aerobic exercise program in patients with mild AD. Methods: In a randomized controlled trial, we recruited...

  16. Differential responsiveness to caffeine and perceived effects of caffeine in moderate and high regular caffeine consumers.

    Science.gov (United States)

    Attwood, A S; Higgs, S; Terry, P

    2007-03-01

    Individual differences in responsiveness to caffeine occur even within a caffeine-consuming population, but the factors that mediate differential responsiveness remain unclear. To compare caffeine's effects on performance and mood in a group of high vs moderate consumers of caffeine and to examine the potential role of subjective awareness of the effects of caffeine in mediating any differential responsiveness. Two groups of regular caffeine consumers (200 mg/day) attended two sessions at which mood and cognitive functions were measured before and 30 min after consumption of 400-mg caffeine or placebo in a capsule. Cognitive tests included visual information processing, match-to-sample visual search (MTS) and simple and choice reaction times. Post-session questionnaires asked participants to describe any perceived effect of capsule consumption. High consumers, but not moderate consumers, demonstrated significantly faster simple and choice reaction times after caffeine relative to placebo. These effects were not attributable to obvious group differences in withdrawal or tolerance because there were no group differences in baseline mood or in reports of negative affect after caffeine. Instead, the high consumers were more likely to report experiencing positive effects of caffeine, whereas the moderate consumers were more likely to report no effect. The sensitivity of caffeine consumers to the mood- and performance-enhancing effects of caffeine is related to their levels of habitual intake. High caffeine consumers are more likely than moderate consumers to perceive broadly positive effects of caffeine, and this may contribute to their levels of use.

  17. Bullying Victimization and Student Engagement in Elementary, Middle, and High Schools: Moderating Role of School Climate

    Science.gov (United States)

    Yang, Chunyan; Sharkey, Jill D.; Reed, Lauren A.; Chen, Chun; Dowdy, Erin

    2018-01-01

    Bullying is the most common form of school violence and is associated with a range of negative outcomes, including traumatic responses. This study used hierarchical linear modeling to examine the multilevel moderating effects of school climate and school level (i.e., elementary, middle, and high schools) on the association between bullying…

  18. Moderate- vs high-dose methadone in the treatment of opioid dependence: a randomized trial.

    Science.gov (United States)

    Strain, E C; Bigelow, G E; Liebson, I A; Stitzer, M L

    1999-03-17

    Methadone hydrochloride treatment is the most common pharmacological intervention for opioid dependence, and recent interest has focused on expanding methadone treatment availability beyond traditional specially licensed clinics. However, despite recommendations regarding effective dosing of methadone, controlled clinical trials of higher-dose methadone have not been conducted. To compare the relative clinical efficacy of moderate- vs high-dose methadone in the treatment of opioid dependence. A 40-week randomized, double-blind clinical trial starting in June 1992 and ending in October 1995. Outpatient substance abuse treatment research clinic at the Johns Hopkins University Bayview Campus, Baltimore, Md. One hundred ninety-two eligible clinic patients. Daily oral methadone hydrochloride in the dose range of 40 to 50 mg (n = 97) or 80 to 100 mg (n = 95), with concurrent substance abuse counseling. Opioid-positive urinalysis results and retention in treatment. By intent-to-treat analysis through week 30 patients in the high-dose group had significantly lower rates of opioid-positive urine samples compared with patients in the moderate-dose group (53.0% [95% confidence interval [CI], 46.9%-59.2%] vs 61.9% [95% CI, 55.9%-68.0%]; P = .047. These differences persisted during withdrawal from methadone. Through day 210 no significant difference was evident between dose groups in treatment retention (high-dose group mean retention, 159 days; moderate-dose group mean retention, 157 days). Nineteen (33%) of 57 patients in the high-dose group and 11 (20%) of 54 patients in the moderate-dose group completed detoxification. Both moderate- and high-dose methadone treatment resulted in decreased illicit opioid use during methadone maintenance and detoxification. The high-dose group had significantly greater decreases in illicit opioid use.

  19. High brilliant thermal and cold moderator for the HBS neutron source project Jülich

    International Nuclear Information System (INIS)

    Cronert, T; Zakalek, P; Rücker, U; Brückel, T; Dabruck, J P; Doege, P E; Nabbi, R; Bessler, Y; Hofmann, M; Butzek, M; Klaus, M; Lange, C; Hansen, W

    2016-01-01

    The proposed High Brilliance Neutron Source (HBS), recognized within the Helmholtz Association of German Research Centres, will optimize the entire chain from particle source through particle accelerator, target, moderator, reflector, shielding, beam extraction, beam transport all the way to the detector, utilizing the nuclear Be(p,n) or Be(d,n) reaction in the lower MeV energy range. A D 2 O moderating reflector prototype (MRP) and a cold source were constructed and build according to MCNP parameter studies. The MRP was tested in a feasibility study at the TREFF instrument at MLZ (Garching). Cold beam extraction from the flux maximum within the moderator based on liquid para H 2 and other cold moderators will be tested by energy spectroscopy via TOF-method. Different ratios of liquid ortho/para H 2 will be fed to the cold moderator. The ratio will be controlled by feeding from reservoires of natural liquid H 2 and a storage loop with an ortho/para converter and determined via online heat capacity measurement. (paper)

  20. Propulsion at low Reynolds number

    International Nuclear Information System (INIS)

    Najafi, Ali; Golestanian, Ramin

    2005-01-01

    We study the propulsion of two model swimmers at low Reynolds number. Inspired by Purcell's model, we propose a very simple one-dimensional swimmer consisting of three spheres that are connected by two arms whose lengths can change between two values. The proposed swimmer can swim with a special type of motion, which breaks the time-reversal symmetry. We also show that an ellipsoidal membrane with tangential travelling wave on it can also propel itself in the direction preferred by the travelling wave. This system resembles the realistic biological animals like Paramecium

  1. Propulsion at low Reynolds number

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, Ali [Institute for Advanced Studies in Basic Sciences, Zanjan 45195-159 (Iran, Islamic Republic of); Faculty of Science, Zanjan University, Zanjan 313 (Iran, Islamic Republic of); Golestanian, Ramin [Institute for Advanced Studies in Basic Sciences, Zanjan 45195-159 (Iran, Islamic Republic of)

    2005-04-13

    We study the propulsion of two model swimmers at low Reynolds number. Inspired by Purcell's model, we propose a very simple one-dimensional swimmer consisting of three spheres that are connected by two arms whose lengths can change between two values. The proposed swimmer can swim with a special type of motion, which breaks the time-reversal symmetry. We also show that an ellipsoidal membrane with tangential travelling wave on it can also propel itself in the direction preferred by the travelling wave. This system resembles the realistic biological animals like Paramecium.

  2. Analysis of high moderation full MOX BWR core physics experiments BASALA

    International Nuclear Information System (INIS)

    Ishii, Kazuya; Ando, Yoshihira; Takada, Naoyuki; Kan, Taro; Sasagawa, Masaru; Kikuchi, Tsukasa; Yamamoto, Toru; Kanda, Ryoji; Umano, Takuya

    2005-01-01

    Nuclear Power Engineering Corporation (NUPEC) has performed conceptual design studies of high moderation full MOX LWR cores that aim for increasing fissile Pu consumption rate and reducing residual Pu in discharged MOX fuel. As part of these studies, NUPEC, French Atomic Energy Commission (CEA) and their industrial partners implemented an experimental program BASALA following MISTRAL. They were devoted to measuring the core physics parameters of such advanced cores. The MISTRAL program consists of one reference UO 2 core, two homogeneous full MOX cores and one full MOX PWR mock-up core that have higher moderation ratio than the conventional lattice. As for MISTRAL, the analysis results have already been reported on April 2003. The BASALA program consists of two high moderation full MOX BWR mock-up cores for operating and cold stand-by conditions. NUPEC has analyzed the experimental results of BASALA with the diffusion and the transport calculations by the SRAC code system and the continuous energy Monte Carlo calculations by the MVP code with the common nuclear data file, JENDL-3.2. The calculation results well reproduce the experimental data approximately within the same range of the experimental uncertainty. The analysis results of MISTRAL and BASALA indicate that these applied analysis methods have the same accuracy for the UO 2 and MOX cores, for the different moderation MOX cores, and for the homogeneous and the mock-up MOX cores. (author)

  3. Experimental study on the Reynolds number dependence of turbulent mixing in a rod bundle

    International Nuclear Information System (INIS)

    Silin, Nicolas; Juanico, Luis

    2006-01-01

    An experimental study for Reynolds number dependence of the turbulent mixing between fuel-bundle subchannels, was performed. The measurements were done on a triangular array bundle with a 1.20 pitch to diameter relation and 10 mm rod diameter, in a low-pressure water loop, at Reynolds numbers between 1.4 x 10 3 and 1.3 x 10 5 . The high accuracy of the results was obtained by improving a thermal tracing technique recently developed. The Reynolds exponent on the mixing rate correlation was obtained with two-digit accuracy for Reynolds numbers greater than 3 x 10 3 . It was also found a marked increase in the mixing rate for lower Reynolds numbers. The weak theoretical base of the accepted Reynolds dependence was pointed out in light of the later findings, as well as its ambiguous supporting experimental data. The present results also provide indirect information about dominant large scale flow pulsations at different flow regimes

  4. Effect of high-hydrostatic pressure and moderate-intensity pulsed electric field on plum.

    Science.gov (United States)

    García-Parra, J; González-Cebrino, F; Delgado-Adámez, J; Cava, R; Martín-Belloso, O; Élez-Martínez, P; Ramírez, R

    2018-03-01

    Moderate intensity pulse electric fields were applied in plum with the aim to increase bioactive compounds content of the fruit, while high-hydrostatic pressure was applied to preserve the purées. High-hydrostatic pressure treatment was compared with an equivalent thermal treatment. The addition of ascorbic acid during purée manufacture was also evaluated. The main objective of this study was to assess the effects on microorganisms, polyphenoloxidase, color and bioactive compounds of high-hydrostatic pressure, or thermal-processed plum purées made of moderate intensity pulse electric field-treated or no-moderate intensity pulse electric field-treated plums, after processing during storage. The application of moderate intensity pulse electric field to plums slightly increased the levels of anthocyanins and the antioxidant activity of purées. The application of Hydrostatic-high pressure (HHP) increased the levels of bioactive compounds in purées, while the thermal treatment preserved better the color during storage. The addition of ascorbic acid during the manufacture of plum purée was an important factor for the final quality of purées. The color and the bioactive compounds content were better preserved in purées with ascorbic acid. The no inactivation of polyphenoloxidase enzyme with treatments applied in this study affected the stability purées. Probably more intense treatments conditions (high-hydrostatic pressure and thermal treatment) would be necessary to reach better quality and shelf life during storage.

  5. Conjoint moderate or high risk alcohol and tobacco use among male out-patients in Thailand

    Directory of Open Access Journals (Sweden)

    Supa Pengpid

    2016-03-01

    Full Text Available Objective: To better understand conjoint alcohol and tobacco use among male hospital out-patients, the purposes of this study were: (1 to assess the prevalence of conjoint use and (2 to determine the factors associated with the conjoint alcohol use and tobacco use. Methods: In a cross-sectional survey, consecutive male out-patients from four district hospitals in Nakhon Pathom province in Thailand were assessed with the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST, Hospital Anxiety and Depression Scale (HADS, selfreported chronic conditions and health-seeking behaviour. The sample included 2208 study participants, with a mean age of 36.2 years (SD = 11.7 and an age range of 18–60 years. Results: Overall, 34.5% of the male hospital out-patients were conjoint moderate or high-risk alcohol and tobacco users, and 31.1% were moderate or high-risk alcohol or tobacco users. In multivariate analysis, younger age, having primary or less education, being separated, divorced or widowed, not having diabetes and not being obese were associated with conjoint moderate or high-risk alcohol and tobacco use. Conclusion: High prevalence and several risk factors of conjoint alcohol and tobacco use were found among hospital male out-patients. The findings of this study call for dual-intervention approaches for both alcohol and tobacco.

  6. The Distinct Biometric Features of High Myopia Compared to Moderate Myopia.

    Science.gov (United States)

    Chung, Hye Jin; Park, Chan Kee

    2016-12-01

    To evaluate changes in biometric parameters in myopic eyes. 412 eyes of 412 young myopic patients underwent ophthalmic examinations including assessments of refractive error, axial length (AL), anterior chamber depth (ACD), and central corneal thickness (CCT). By using spectral domain optical coherence tomography (SD-OCT), peripapillary retinal nerve fiber layer (pRNFL) thickness was measured. Subjects were divided into two groups: a moderate-myope group (-6 diopters (D) or more) and a high-myope group (less than -6 D). The relationships among ocular biometric parameters including pRNFL thickness, AL, ACD, and CCT were calculated for each group. In the moderate-myopia group, the anterior chamber deepened as AL increased (Pearson's coefficient = 0.346, p biometric parameter in highly myopic eyes should consider these differences.

  7. Femtosecond laser based small incision lenticule extraction for moderate and high myopia

    DEFF Research Database (Denmark)

    Hjortdal, Jesper Østergaard; Asp, Sven; Ivarsen, Anders

    Femtosecond laser based small incision lenticule extraction for moderate and high myopia. Jesper Hjortdal, Sven Asp, Anders Ivarsen, Anders Vestergaard Department of Ophthalmology, Aarhus University Hospital, Denmark Purpose: ReLEx® smile is a new keratorefractive procedure whereby a stromal lent....... Refractive predictability, safety and patient satisfaction at 3 months seems equal to ReLEx flex and FS-LASIK. Optimizing laser energy settings and surgeon experience is important to minimize initial inferior results....

  8. Reynolds-number dependence of turbulence enhancement on collision growth

    Directory of Open Access Journals (Sweden)

    R. Onishi

    2016-10-01

    Full Text Available This study investigates the Reynolds-number dependence of turbulence enhancement on the collision growth of cloud droplets. The Onishi turbulent coagulation kernel proposed in Onishi et al. (2015 is updated by using the direct numerical simulation (DNS results for the Taylor-microscale-based Reynolds number (Reλ up to 1140. The DNS results for particles with a small Stokes number (St show a consistent Reynolds-number dependence of the so-called clustering effect with the locality theory proposed by Onishi et al. (2015. It is confirmed that the present Onishi kernel is more robust for a wider St range and has better agreement with the Reynolds-number dependence shown by the DNS results. The present Onishi kernel is then compared with the Ayala–Wang kernel (Ayala et al., 2008a; Wang et al., 2008. At low and moderate Reynolds numbers, both kernels show similar values except for r2 ∼ r1, for which the Ayala–Wang kernel shows much larger values due to its large turbulence enhancement on collision efficiency. A large difference is observed for the Reynolds-number dependences between the two kernels. The Ayala–Wang kernel increases for the autoconversion region (r1, r2 < 40 µm and for the accretion region (r1 < 40 and r2 > 40 µm; r1 > 40 and r2 < 40 µm as Reλ increases. In contrast, the Onishi kernel decreases for the autoconversion region and increases for the rain–rain self-collection region (r1, r2 > 40 µm. Stochastic collision–coalescence equation (SCE simulations are also conducted to investigate the turbulence enhancement on particle size evolutions. The SCE with the Ayala–Wang kernel (SCE-Ayala and that with the present Onishi kernel (SCE-Onishi are compared with results from the Lagrangian Cloud Simulator (LCS; Onishi et al., 2015, which tracks individual particle motions and size evolutions in homogeneous isotropic turbulence. The SCE-Ayala and SCE-Onishi kernels show consistent

  9. Luck, come here! Automatic approach tendencies toward gambling cues in moderate- to high-risk gamblers.

    Science.gov (United States)

    Boffo, Marilisa; Smits, Ruby; Salmon, Joshua P; Cowie, Megan E; de Jong, David T H A; Salemink, Elske; Collins, Pam; Stewart, Sherry H; Wiers, Reinout W

    2018-02-01

    Similar to substance addictions, reward-related cognitive motivational processes, such as selective attention and positive memory biases, have been found in disordered gambling. Despite findings that individuals with substance use problems are biased to approach substance-related cues automatically, no study has yet focused on automatic approach tendencies for motivationally salient gambling cues in problem gamblers. We tested if moderate- to high-risk gamblers show a gambling approach bias and whether this bias was related prospectively to gambling behaviour and problems. Cross-sectional assessment study evaluating the concurrent and longitudinal correlates of gambling approach bias in moderate- to high-risk gamblers compared with non-problem gamblers. Online study throughout the Netherlands. Twenty-six non-treatment-seeking moderate- to high-risk gamblers and 26 non-problem gamblers community-recruited via the internet. Two online assessment sessions 6 months apart, including self-report measures of gambling problems and behaviour (frequency, duration and expenditure) and the gambling approach avoidance task, with stimuli tailored to individual gambling habits. Relative to non-problem gamblers, moderate- to high-risk gamblers revealed a stronger approach bias towards gambling-related stimuli than neutral stimuli (P = 0.03). Gambling approach bias was correlated positively with past-month gambling expenditure at baseline (P = 0.03) and with monthly frequency of gambling at follow-up (P = 0.02). In multiple hierarchical regressions, baseline gambling approach bias predicted monthly frequency positively (P = 0.03) and total duration of gambling episodes (P = 0.01) 6 months later, but not gambling problems or expenditure. In the Netherlands, relative to non-problem gamblers, moderate- to high-risk gamblers appear to have a stronger tendency to approach rather than to avoid gambling-related pictures compared with neutral ones. This gambling approach bias is

  10. Attentional bias to emotional stimuli is altered during moderate- but not high-intensity exercise.

    Science.gov (United States)

    Tian, Qu; Smith, J Carson

    2011-12-01

    Little is known regarding how attention to emotional stimuli is affected during simultaneously performed exercise. Attentional biases to emotional face stimuli were assessed in 34 college students (17 women) using the dot-probe task during counterbalanced conditions of moderate- (heart rate at 45% peak oxygen consumption) and high-intensity exercise (heart rate at 80% peak oxygen consumption) compared with seated rest. The dot-probe task consisted of 1 emotional face (pleasant or unpleasant) paired with a neutral face for 1,000 ms; 256 trials (128 trials for each valence) were presented during each condition. Each condition lasted approximately 10 min. Participants were instructed to perform each trial of the dot-probe task as quickly and accurately as possible during the exercise and rest conditions. During moderate-intensity exercise, participants exhibited significantly greater attentional bias scores to pleasant compared with unpleasant faces (p bias scores to emotional faces did not differ at rest or during high-intensity exercise (p > .05). In addition, the attentional bias to unpleasant faces was significantly reduced during moderate-intensity exercise compared with that during rest (p emotional stimuli and away from unpleasant emotional stimuli. Future work is needed to determine whether acute exercise may be an effective treatment approach to reduce negative bias or enhance positive bias in individuals diagnosed with mood or anxiety disorders, or whether attentional bias during exercise predicts adherence to exercise. (c) 2011 APA, all rights reserved.

  11. Developments of high-performance moderator vessel for JRR-3 cold neutron source

    International Nuclear Information System (INIS)

    Arai, Masaji; Tamura, Itaru; Hazawa, Tomoya

    2015-05-01

    The cold neutron source (CNS) facility converts thermal neutrons into cold neutrons to moderate neutrons with liquid hydrogen. The cold neutron beam at Japan Research Reactor No. 3 (JRR-3) is led to the beam experimental devices in the beam hall through neutron guide tubes. High intensities of the cold neutron beam are always demanded for increasing the experimental effectiveness and accuracy. In the Department of Research Reactor and Tandem Accelerator, developments of high-performance CNS moderator vessel that can produce cold neutron intensity about two times higher compared to the existing vessel have been performed in the second medium term plans. We compiled this report about the technological development to solve several problems with the design and manufacture of new vessel. In the present study, design strength evaluation, mockup test, simulation for thermo-fluid dynamics of the liquid hydrogen and strength evaluation of the different-material-bonding were studied. By these evaluation results, we verified that the developed new vessel can be applied to CNS moderator vessel of JRR-3. (author)

  12. Study of plutonium multi-recycle in high moderation LWR cores

    International Nuclear Information System (INIS)

    Iwata, Yutaka; Yamamoto, Toru; Ueji, Masao; Hibi, Koki; Aoyama, Motoo; Sakurada, Koichi

    2000-01-01

    Nuclear Power Engineering Corporation (NUPEC) has been studying advanced cores that are dedicated to enhance the plutonium consumption per recycling for effective use of plutonium. In this study, a fissile plutonium consumption rate is adopted as an index of the effective use of plutonium, which is defined as a ratio of consumption to loading of fissile plutonium in a core. High moderation core concepts have been studied in order to increase this index based on full MOX cores in the latest designs of LWRs in Japan that are the Advanced Boiling Water Reactor (ABWR) and the Advanced Pressurized Water Reactor (APWR). As a part of this study, core performance in the case of plutonium multi-recycling has been surveyed with these higher moderation cores aiming further effective use of plutonium. The design and analyses for equilibrium cores show that nuclear and thermal hydraulics parameters satisfy design criteria, and a fissile plutonium consumption rate increases up to 20% for ABWRs and 30% for APWRs even in plutonium multi-recycling condition. It was confirmed that the high moderation cores are feasible from a viewpoint of nuclear and thermal hydraulics, safety and plutonium consumption in the condition of plutonium multi-recycling. (author)

  13. Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows

    KAUST Repository

    Scribano, Gianfranco; Bisetti, Fabrizio

    2016-01-01

    dependence of the velocity field with respect to the separation ratio is linked to a high pressure region at the stagnation point. On the other hand, Reynolds number effects highlight the role played by the wall boundary layer on the interior of the nozzles

  14. Reynolds stress and shear flow generation

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Michelsen, Poul; Naulin, V.

    2001-01-01

    The so-called Reynolds stress may give a measure of the self-consistent flow generation in turbulent fluids and plasmas by the small-scale turbulent fluctuations. A measurement of the Reynolds stress can thus help to predict flows, e.g. shear flows in plasmas. This may assist the understanding...... of improved confinement scenarios such as H-mode confinement regimes. However, the determination of the Reynolds stress requires measurements of the plasma potential, a task that is difficult in general and nearly impossible in hot plasmas in large devices. In this work we investigate an alternative method......, based on density measurements, to estimate the Reynolds stress, and demonstrate the validity range of this quantity, which we term the pseudo-Reynolds stress. The advantage of such a quantity is that accurate measurements of density fluctuations are much easier to obtain experimentally. Prior...

  15. Moderate temperature gas purification system: application to high calorific coal derived fuel

    Energy Technology Data Exchange (ETDEWEB)

    M. Kobayashi; H. Shirai; M. Nunokawa [Central Research Institute of Electric Power Industry (CRIEPI), Kanagawa (Japan)

    2005-07-01

    Simultaneous removal of dust, alkaline and alkaline-earth metals, halides and sulfur compounds is required to enlarge application of coal-derived gas to the high temperature fuel cells and the fuel synthesis through chemical processing. Because high calorific fuel gas, such as oxygen-blown coal gas, has high carbon monoxide content, high temperature gas purification system is always subjected to the carbon deposition and slippage of contaminant of high vapor pressure. It was suggested that moderate temperature operation of the gas purification system is applied to avoid the harmful disproportionation reaction and efficient removal of the various contaminants. To establish the moderate temperature gas purification system, the chemical-removal processes where the reaction rate is predominant to the performance of contaminant removal should be evaluated. Performance of the removal processes for halides and sulfur compounds were experimentally evaluated. The halide removal process with sodium based sorbent had potential good performance at around 300{sup o}C. The sulfur removal process was also applicable to the temperature range, although the improvement of the sulfidation reaction rate is considered to be essential. 11 refs., 8 figs., 1 tab.

  16. Universal model of finite Reynolds number turbulent flow in channels and pipes

    NARCIS (Netherlands)

    L'vov, V.S.; Procaccia, I.; Rudenko, O.

    2008-01-01

    In this Letter, we suggest a simple and physically transparent analytical model of pressure driven turbulent wall-bounded flows at high but finite Reynolds numbers Re. The model provides an accurate quantitative description of the profiles of the mean-velocity and Reynolds stresses (second order

  17. Moderate temperature gas purification system: Application to high calorific coal-derived fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, M.; Shirai, H.; Nunokawa, M. [Central Research Institute of Electric Power Industry, Kanagawa (Japan)

    2008-01-15

    Simultaneous removal of dust, alkaline and alkaline-earth metals, halides and sulfur compounds is required to enlarge application of coal-derived gas to the high-temperature fuel cells and the fuel synthesis through chemical processing. Because high calorific fuel gas, such as oxygen-blown coal gas, has high carbon monoxide content, high-temperature (above 450{sup o}C) gas purification system is always subjected to the carbon deposition. We suggest moderate temperature (around 300{sup o}C) operation of the gas purification system to avoid the harmful disproportionation reaction and efficient removal of the various contaminants. Because the reaction rate is predominant to the performance of contaminant removal in the moderate temperature gas purification system, we evaluated the chemical removal processes; performance of the removal processes for halides and sulfur compounds was experimentally evaluated. The halide removal process with sodium aluminate sorbent had potential performance at around 300{sup o}C. The sulfur removal process with zinc ferrite sorbent was also applicable to the temperature range, though the reaction kinetics of the sorbent is essential to be approved.

  18. Plasma Irisin Modestly Increases during Moderate and High-Intensity Afternoon Exercise in Obese Females

    Science.gov (United States)

    Winn, Nathan C.; Grunewald, Zachary I.; Liu, Ying; Heden, Timothy D.; Nyhoff, Lauren M.; Kanaley, Jill A.

    2017-01-01

    Background and Purpose Irisin is an exercise-responsive myokine that has been proposed to exert anti-obesity benefits; yet its response during exercise in obese women is not described. This study characterized plasma irisin levels during a single bout of afternoon isocaloric-exercise of different intensities (moderate- vs high-intensity) in obese females. Methods Eleven obese females participated in 3 randomized study days beginning at 1600h: 1) no exercise (NoEx), 2) moderate exercise (ModEx; 55%VO2max) and 3) high intensity interval exercise (IntEx; 4 min (80%VO2max)/3 min (50% VO2max). Frequent blood samples were analyzed for glucose and lactate (whole-blood), and insulin, c-peptide, glucagon, and irisin (plasma) throughout 190 min of testing. Results Plasma irisin increased above baseline during ModEx and IntEx (P0.05). Peak irisin levels during ModEx and IntEx exercise were 11.9± 3.4% and 12.3 ± 4.1% relative to baseline (Pexercise intensities (P>0.05). Irisin levels remained elevated above resting for 125 minutes post-exercise during ModEx, whereas levels returned to baseline within 15 minutes post-exercise during IntEx. Similarly, no associations were found between plasma irisin levels and circulating lactate, glucose, insulin, c-peptide, or glucagon among study days (P>0.05). However, there was an inverse association between basal irisin and lean mass (r = -0.70, P = 0.01). Conclusion A single bout of moderate and high intensity afternoon exercise induces modest increases in circulating irisin concentrations during exercise; however the regulation post-exercise appears to be dimorphic between exercise intensity in obese females. Future studies are needed to compare morning and afternoon exercise on irisin secretion. PMID:28125733

  19. Effect of moderate- and high-intensity acute exercise on appetite in obese individuals

    DEFF Research Database (Denmark)

    Martins, Catia; Stensvold, Dorthe; Finlayson, Graham

    2015-01-01

    PURPOSE: The effect of acute exercise, and exercise intensity, on appetite control in obese individuals requires further study. The aim of this study was to compare the effects of acute isocaloric bouts (250 kcal) of high-intensity intermittent cycling (HIIC) and moderate-intensity continuous....../obese volunteers. Participants were assigned to the control, MICC, HIIC, and S-HIIC conditions, 1 wk apart, in a counterbalanced order. Exercise was performed 1 h after a standard breakfast. An ad libitum test lunch was served 3 h after breakfast. Fasting/postprandial plasma samples of insulin, acylated ghrelin...

  20. Moderate-to-High Intensity Physical Exercise in Patients with Alzheimer's Disease

    DEFF Research Database (Denmark)

    Hoffmann, Kristine; Sobol, Nanna A; Frederiksen, Kristian S

    2016-01-01

    BACKGROUND: Studies of physical exercise in patients with Alzheimer's disease (AD) are few and results have been inconsistent. OBJECTIVE: To assess the effects of a moderate-to-high intensity aerobic exercise program in patients with mild AD. METHODS: In a randomized controlled trial, we recruite...... reduced neuropsychiatric symptoms in patients with mild AD, with possible additional benefits of preserved cognition in a subgroup of patients exercising with high attendance and intensity.......BACKGROUND: Studies of physical exercise in patients with Alzheimer's disease (AD) are few and results have been inconsistent. OBJECTIVE: To assess the effects of a moderate-to-high intensity aerobic exercise program in patients with mild AD. METHODS: In a randomized controlled trial, we recruited...... 200 patients with mild AD to a supervised exercise group (60-min sessions three times a week for 16 weeks) or to a control group. Primary outcome was change from baseline in cognitive performance estimated by Symbol Digit Modalities Test (SDMT) in the intention-to-treat (ITT) group. Secondary outcomes...

  1. Dietary B vitamin needs of strains of pigs with high and moderate lean growth.

    Science.gov (United States)

    Stahly, T S; Williams, N H; Lutz, T R; Ewan, R C; Swenson, S G

    2007-01-01

    Ten sets of 5 littermate pigs from each of 2 genetic strains were utilized to determine the impact of the dietary concentration of 5 B vitamins (riboflavin, niacin, pantothenic acid, cobalamin, and folacin) on growth from 9 to 28 kg of BW in pigs with high or moderate capacity for lean growth. All pigs (penned individually) were reared via a segregated, early weaning scheme, so that the lean growth potential of each strain could be expressed. The basal diet provided the 5 test vitamins at concentrations of total and estimated bioavailability equivalent to a minimum of 100 and 70%, respectively, of their estimated requirements (NRC, 1998) for 5- to 10-kg pigs. At a BW of 9 +/- 0.9 kg, pigs within each litter were allotted to the basal diet supplemented with sources of the 5 test vitamins equivalent to an additional 0, 100, 200, 300, or 400% (bioavailable) of the NRC requirements. Pigs from the high lean strain consumed less feed (P vitamin concentrations were increased. However, the dietary B vitamin concentrations needed to optimize G:F were greater (P 470% of NRC, 1998) vs. moderate (270%) lean strain. Based on these data, the dietary needs for 1 or more of the 5 B vitamins are greater than current NRC (1998) estimates, particularly in pigs expressing a high rate of lean tissue growth. The greater need for these vitamins is not associated with greater dietary energy intake or body energy accretion rate but is potentially due to shifts in the predominant metabolic pathways.

  2. Moderate Recovery Unnecessary to Sustain High Stroke Volume during Interval Training. A Brief Report

    Directory of Open Access Journals (Sweden)

    Jamie Stanley

    2014-06-01

    Full Text Available It has been suggested that the time spent at a high stroke volume (SV is important for improving maximal cardiac function. The aim of this study was to examine the effect of recovery intensity on cardiovascular parameters during a typical high-intensity interval training (HIIT session in fourteen well-trained cyclists. Oxygen consumption (VO2, heart rate (HR, SV, cardiac output (Qc, and oxygenation of vastus lateralis (TSI were measured during a HIIT (3×3-min work period, 2 min of recovery session on two occasions. VO2, HR and Qc were largely higher during moderate-intensity (60% compared with low-intensity (30% (VO2, effect size; ES = +2.6; HR, ES = +2.8; Qc, ES = +2.2 and passive (HR, ES = +2.2; Qc, ES = +1.7 recovery. By contrast, there was no clear difference in SV between the three recovery conditions, with the SV during the two active recovery periods not being substantially different than during exercise (60%, ES = −0.1; 30%, ES = −0.2. To conclude, moderate-intensity recovery may not be required to maintain a high SV during HIIT.

  3. High Rate of Recurrence Following Proximal Medial Opening Wedge Osteotomy for Correction of Moderate Hallux Valgus.

    Science.gov (United States)

    Iyer, Sravisht; Demetracopoulos, Constantine A; Sofka, Carolyn M; Ellis, Scott J

    2015-07-01

    The proximal medial opening wedge (PMOW) osteotomy has become more popular to treat moderate to severe hallux valgus with the recent development of specifically designed, low-profile modular plates. Despite the promising results previously reported in the literature, we have noted a high incidence of recurrence in patients treated with a PMOW. The purpose of this study was to report the clinical and radiographic outcomes of an initial cohort of patients treated with a PMOW osteotomy for moderate hallux valgus. We retrospectively analyzed prospectively gathered data on a cohort of 17 consecutive patients who were treated by the senior author using a PMOW osteotomy for moderate hallux valgus deformity. Average time to follow-up was 2.4 years (range, 1.0-3.5 years). The intermetatarsal angle (IMA), the hallux valgus angle (HVA), and the distal metatarsal articular angle (DMAA) were assessed on standard weightbearing radiographs of the foot preoperatively and at all follow-up visits. The Foot and Ankle Outcome Score (FAOS) was collected on all patients preoperatively and at final follow-up. Despite demonstrating good correction of their deformity initially, 11 of the 17 patients (64.7%) had evidence of recurrence of their hallux valgus deformity at final follow-up. Patients who recurred had a greater preoperative HVA (P = .023) and DMAA (P = .049) than patients who maintained their correction. Improvement in the quality-of-life subscale of the FAOS was noted at final follow-up for all patients (P = .05). There was no significant improvement in any of the other FAOS subscales. There was a high rate of recurrence of the hallux valgus deformity in this cohort of patients. Recurrence was associated with greater preoperative deformity and an increased preoperative DMAA. The PMOW without a concomitant distal metatarsal osteotomy may be best reserved for patients with mild hallux valgus deformity without an increased DMAA. Level IV, retrospective case series. © The Author

  4. Microbiological quality and safety assessment in the production of moderate and high humidity cheeses

    Directory of Open Access Journals (Sweden)

    Denise da Fontoura Prates

    2017-10-01

    Full Text Available ABSTRACT: Moderate and high humidity cheeses are described as important vehicles of pathogens in many foodborne diseases outbreaks. Microbial contamination can occur in raw material or in the different steps of the product processing due to inadequate hygiene practices. Thus, the aim of this study was to evaluate the microbiological quality and safety in the production of moderate and high humidity cheese. Samples from raw milk, handlers’ hands surface, final product were collected in three cheese manufacturing plants located in southern Brazil, with different levels of sanitary control. Effectiveness of milk pasteurization was also evaluated. Thermotolerant coliforms, coagulase-positive staphylococci (CPS, Salmonella spp., and Listeria monocytogenes were evaluated. Raw milk samples showed the highest contamination levels, with enumeration of 1.1x105 most probable number (MPN mL-1 for thermotolerant coliforms, 4x105 colony-forming units (CFU mL-1 for CPS and presence of Salmonella spp. CPS were also reported in one sample of handler’s hands surface. However, only one sample of the final product was out of Brazilian regulatory standards, exceeding the limit allowed for CPS. Milk pasteurization process used in cheese preparation was effective, regardless the level of sanitary control of the industries. Results highlighted the need for better hygiene practices, in obtaining the raw milk and in the handling during the cheese manufacturing steps.

  5. ARTERIAL STIFFNESS PARAMETERS IN PATIENTS WITH MODERATE/HIGH CARDIOVASCULAR RISK DURING LISINOPRIL AND SIMVASTATIN TREATMENT

    Directory of Open Access Journals (Sweden)

    V. N. Isakova

    2016-01-01

    Full Text Available Aim. To evaluate parameters of arterial stiffness by non-invasive arteriography in patients with moderate/high cardiovascular risk receiving lisinopril and simvastatin.Material and methods. 20 patients (aged 50-55 y.o. with arterial hypertension of the 1st degree and dislipidemia are included in the study. All patients had pulse wave velocity (PWV ≥ 10 m/s and/or the corrected index of pulse wave augmentation (AI × 80 ≥ -10% according to non-invasive arteriography data; and moderate-high cardiovascular risk (≥ 3%. Patients received therapy with lisinopril and simvastatin. Blood pressure (BP levels and lipid profiles were assessed before therapy and in 1, 2, 6 and 12 month of the observation. Non-invasive arteriography was performed before therapy and in 2, 6 and 12 months later.Results. BP target levels were reached within 1 month of treatment as well as improvement of lipid profile was reached within 2 months in majority of the patients. Reference PWV and AI were reached in 85,7% of patients within one year of treatment.Conclusion. Arterial stiffness parameters help to evaluate cardiovascular risk changes accurately as the results of treatment.

  6. Particle-pair relative velocity measurement in high-Reynolds-number homogeneous and isotropic turbulence using 4-frame particle tracking velocimetry

    Science.gov (United States)

    Dou, Zhongwang; Ireland, Peter J.; Bragg, Andrew D.; Liang, Zach; Collins, Lance R.; Meng, Hui

    2018-02-01

    The radial relative velocity (RV) between particles suspended in turbulent flow plays a critical role in droplet collision and growth. We present a simple and accurate approach to RV measurement in isotropic turbulence—planar 4-frame particle tracking velocimetry—using routine PIV hardware. It improves particle positioning and pairing accuracy over the 2-frame holographic approach by de Jong et al. (Int J Multiphas Flow 36:324-332; de Jong et al., Int J Multiphas Flow 36:324-332, 2010) without using high-speed cameras and lasers as in Saw et al. (Phys Fluids 26:111702, 2014). Homogeneous and isotropic turbulent flow ({R_λ }=357) in a new, fan-driven, truncated iscosahedron chamber was laden with either low-Stokes (mean St=0.09, standard deviation 0.05) or high-Stokes aerosols (mean St=3.46, standard deviation 0.57). For comparison, DNS was conducted under similar conditions ({R_λ }=398; St=0.10 and 3.00, respectively). Experimental RV probability density functions (PDF) and mean inward RV agree well with DNS. Mean inward RV increases with St at small particle separations, r, and decreases with St at large r, indicating the dominance of "path-history" and "inertial filtering" effects, respectively. However, at small r, the experimental mean inward RV trends higher than DNS, possibly due to the slight polydispersity of particles and finite light sheet thickness in experiments. To confirm this interpretation, we performed numerical experiments and found that particle polydispersity increases mean inward RV at small r, while finite laser thickness also overestimates mean inward RV at small r, This study demonstrates the feasibility of accurately measuring RV using routine hardware, and verifies, for the first time, the path-history and inertial filtering effects on particle-pair RV at large particle separations experimentally.

  7. Effect of surface roughness and Reynolds number on compressor cascade performance

    International Nuclear Information System (INIS)

    Back, Seung Chul; Song, Seung Jin

    2009-01-01

    An experimental work has been conducted in a linear compressor cascade to find out the effect of surface roughness and Reynolds number. Surveys were conducted with different roughness size and Reynolds number. The k s /c value of each roughness is 0.0006, 0.0090, 0.00150, 0.00213, and 0.00425. The range of Reynolds number is 300,000∼600,000 and conducted with roughened blade, which roughness Ra is 2.89 microns. Flow pressure, velocity, and angle have been found out via 5 hole probe. Pressure loss and deviation increased with increasing roughness. In the low Reynolds number under 500,000, tested roughness does not affect to the performance of compressor cascade. However, roughness is very sensitive to pressure loss in high Reynolds number over 550,000.

  8. Neutronic performance of decoupled poisoned and unpoisoned composite moderators for high resolution experiments

    International Nuclear Information System (INIS)

    Kai, Tetsuya; Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Sakata, Hideaki; Ikeda, Yujiro

    2001-01-01

    We studied decoupled poisoned and un-poisoned composite moderators consisting of 20 mm thick hydrogen and 30 mm thick light water. The neutron pulses from un-poisoned one were much broader with longer decay times than a simple decoupled hydrogen moderator in 50 mm thickness. It was also found that the poisoned composite moderator provides higher pulse peak intensities relative to the hydrogen moderator (poisoned at 20 mm) below several tens meV with no penalty of pulse width. (author)

  9. High-Intensity Interval or Continuous-Moderate Exercise: A 24-Week Pilot Trial.

    Science.gov (United States)

    Locke, Sean R; Bourne, Jessica E; Beauchamp, Mark R; Little, Jonathan P; Barry, Julianne; Singer, Joel; Jung, Mary E

    2018-05-14

    High-intensity interval training (HIIT) may lead to superior cardiometabolic improvements when compared to moderate-intensity continuous training (MICT). However, adherence to HIIT requires examination. The purpose of this pilot study was to examine moderate-to-vigorous physical activity (MVPA) adherence 24 weeks following a brief counselling intervention combined with either HIIT or MICT. Individuals at high risk of type 2 diabetes (T2D) were randomized to HIIT (n = 15) or MICT (n = 17) and completed 10 exercise sessions accompanied by a brief 10-minute counselling intervention over a 2-week period. Objectively measured purposeful MVPA (accelerometry) and cardiorespiratory fitness (VO2peak) were assessed at baseline and 24 weeks post-intervention. Self-regulatory efficacy and task self-efficacy were examined at baseline, post-intervention and 24 weeks post-intervention. Using an intention-to-treat analysis, change scores were calculated for HIIT and MICT and compared between groups. Individuals assigned to HIIT increased their MVPA by 53 minutes (Cohen's d=1.52) at 24 weeks compared to 19 minutes in MICT (tbetween=1.96, p=.06, d =.56). Both HIIT and MICT increased relative VO2peak by 2 and 1 ml/kg/min, respectively (tbetween=0.72, p=0.47). Participants in both groups increased in their self-regulatory and task self-efficacy post-intervention but both groups demonstrated similar decline at 24 weeks. This pilot intervention was successful in increasing, and maintaining, free-living MVPA over a 24-week period in individuals at high risk of T2D. Speculation that HIIT is inappropriate or unattainable for overweight individuals at high risk of T2D may be unfounded.

  10. The effect of lower anterior high pull headgear on treatment of moderate open bite in adults

    Directory of Open Access Journals (Sweden)

    Rahman Showkatbakhsh

    2012-01-01

    Full Text Available Background and Aims: Various methods are used for treatment of open bite. The objective of this study was to investigate the effects of Lower Anterior High Pull Headgear (LAHPH appliance in Class I subjects with moderate open bite and high lower lip line.Materials and Methods: The study group was composed of 10 subjects with a mean age of 15.8±2.5 years and 3.05 ± 0.07 mm moderate open bite. All the patients rejected orthognathic surgery. The treatment included extraction of upper and lower second premolars followed by leveling, banding, bonding, posterior space closure, and anterior retraction. After these procedures, the open bite was reduced to 2.04±1.17 mm. Afterwards, LAHPH was applied for 18 hours per day for 8±2 months. LAHPH appliance was composed of High Pull Headgear and two hooks mounted on its inner bow. Two elastics (1.8, light, Dentaurum connected the upper hooks on the inner bow to the lower hooks on the mandibular canines vertically. The forces produced by the prescribed elastics were 10 and 60 g during mouth closing and opening, respectively. Paired T-test was used to evaluate pre-andpost-treatment outcomes.Results: The pre-and post-treatment cephalometric evaluations showed that the LAHPH reduced effectively the open bite of the patients to 0.15±1.7 mm (P<0.001.Conclusion: This appliance can be used as an acceptable method for closing the open bite in Class I subjects.

  11. FLUKA simulations of a moderated reduced weight high energy neutron detection system

    Energy Technology Data Exchange (ETDEWEB)

    Biju, K., E-mail: bijusivolli@gmail.com [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tripathy, S.P.; Sunil, C.; Sarkar, P.K. [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-08-01

    Neutron response of the systems containing high density polyethylene (HDPE) spheres coupled with different external metallic converters has been studied using the FLUKA Monte Carlo simulation code. A diameter of 17.8 cm (7 in.) of the moderating sphere is found to be optimum to obtain the maximum response when used with the neutron converter shells like W, Pb and Zr. Enhancement ratios of the neutron response due to the induced (n, xn) reactions in the outer converters made of W, Pb and Zr are analyzed. It is observed that the enhancement in the response by 1 cm thick Zr shell is comparable to that of 1 cm thick Pb in the energy region of 10-50 MeV. An appreciable enhancement is observed in the case of Zr converter for the higher energy neutrons. Thus, by reducing the dimension of the moderating sphere and using a Zr converter shell, the weight of the system reduces to 10 kg which is less compared to the presently available extended high energy neutron rem meters. The normalized energy dependent ambient dose equivalent response of the zirconium based rem counter (ZReC) at high energies is found to be in good agreement with the energy differential H{sup Low-Asterisk }(10) values suggested by the International Commission on Radiological Protection (ICRP). Based on this study, it is proposed that a rem meter made of 17.8 cm diameter HDPE sphere with 1 cm thick Zr can be used effectively and conveniently for routine monitoring in the accelerator environment.

  12. Effect of moderate- and high-intensity acute exercise on appetite in obese individuals.

    Science.gov (United States)

    Martins, Catia; Stensvold, Dorthe; Finlayson, Graham; Holst, Jens; Wisloff, Ulrik; Kulseng, Bård; Morgan, Linda; King, Neil A

    2015-01-01

    The effect of acute exercise, and exercise intensity, on appetite control in obese individuals requires further study. The aim of this study was to compare the effects of acute isocaloric bouts (250 kcal) of high-intensity intermittent cycling (HIIC) and moderate-intensity continuous cycling (MICC) or short-duration HIIC (S-HIIC) (125 kcal) and a resting control condition on the appetite hormone responses, subjective feelings of appetite, energy intake (EI), and food reward in overweight/obese individuals. This study is a randomized crossover study on 12 overweight/obese volunteers. Participants were assigned to the control, MICC, HIIC, and S-HIIC conditions, 1 wk apart, in a counterbalanced order. Exercise was performed 1 h after a standard breakfast. An ad libitum test lunch was served 3 h after breakfast. Fasting/postprandial plasma samples of insulin, acylated ghrelin, polypeptide YY3-36, and glucagon-like peptide 1 and subjective feelings of appetite were measured every 30 min for 3 h. Nutrient and taste preferences were measured at the beginning and end of each condition using the Leeds Food Preference Questionnaire. Insulin levels were significantly reduced, and glucagon-like peptide 1 levels significantly increased during all exercise bouts compared with those during rest. Acylated ghrelin plasma levels were lower in the MICC and HIIC, but not in S-HIIC, compared with those in control. There were no significant differences for polypeptide YY3-36 plasma levels, hunger or fullness ratings, EI, or food reward. Our findings suggest that, in overweight/obese individuals, isocaloric bouts of moderate- or high-intensity exercise lead to a similar appetite response. This strengthens previous findings in normal-weight individuals that acute exercise, even at high intensity, does not induce any known physiological adaptation that would lead to increased EI.

  13. Using high thermal stability flexible thin film thermoelectric generator at moderate temperature

    Science.gov (United States)

    Zheng, Zhuang-Hao; Luo, Jing-Ting; Chen, Tian-Bao; Zhang, Xiang-Hua; Liang, Guang-Xing; Fan, Ping

    2018-04-01

    Flexible thin film thermoelectric devices are extensively used in the microscale industry for powering wearable electronics. In this study, comprehensive optimization was conducted in materials and connection design for fabricating a high thermal stability flexible thin film thermoelectric generator. First, the thin films in the generator, including the electrodes, were prepared by magnetron sputtering deposition. The "NiCu-Cu-NiCu" multilayer electrode structure was applied to ensure the thermal stability of the device used at moderate temperature in an air atmosphere. A design with metal layer bonding and series accordant connection was then employed. The maximum efficiency of a single PN thermocouple generator is >11%, and the output power loss of the generator is <10% after integration.

  14. Thrombocytopenia in Moderate- to High-Risk Sutureless Aortic Valve Replacement

    Directory of Open Access Journals (Sweden)

    Puwadon Thitivaraporn

    2018-06-01

    Full Text Available Background : This study aimed to compare preliminary data on the outcomes of sutureless aortic valve replacement (SU-AVR with those of aortic valve replacement (AVR. Methods : We conducted a retrospective study of SU-AVR in moderate- to high-risk patients from 2013 to 2016. Matching was performed at a 1:1 ratio using the Society of Thoracic Surgeons predicted risk of mortality score with sex and age. The primary outcome was 30-day mortality. The secondary outcomes were operative outcomes and complications. Results : A total of 277 patients were studied. Ten patients (50% males; median age, 81.5 years underwent SU-AVR. Postoperative echocardiography showed impressive outcomes in the SU-AVR group. The 30-day mortality was 10% in both groups. In our study, the patients in the SU-AVR group developed postoperative thrombocytopenia. Platelet counts decreased from 225X103 /μL preoperatively to 94.5, 54.5, and 50.1X10 3/μL on postoperative days 1, 2, and 3, respectively, showing significant differences compared with the AVR group (p=0.04, p=0.16, and p=0.20, respectively. The median amount of platelet transfusion was higher in the AVR group (12.5 vs. 0 units, p=0.052. Conclusion : There was no difference in the 30-day mortality of moderate- to high-risk patients depending on whether they underwent SU-AVR or AVR. Although SU-AVR is associated with favorable cardiopulmonary bypass and cross-clamp times, it may be associated with postoperative thrombocytopenia.

  15. A "high severity" spruce beetle outbreak in Wyoming causes moderate-severity carbon cycle perturbations

    Science.gov (United States)

    Berryman, E.; Frank, J. M.; Speckman, H. N.; Bradford, J. B.; Ryan, M. G.; Massman, W. J.; Hawbaker, T. J.

    2017-12-01

    Bark beetle outbreaks in Western North American forests are often considered a high-severity disturbance from a carbon (C) cycling perspective, but field measurements that quantify impacts on C dynamics are very limited. Often, factors out of the researcher's control complicate the separation of beetle impacts from other drivers of C cycling variability and restrict statistical inference. Fortuitously, we had four years of pre-spruce beetle outbreak C cycle measurements in a subalpine forest in southeastern Wyoming (Glacier Lakes Ecosystem Experiments Site, or GLEES) and sustained intermittent monitoring for nearly a decade after the outbreak. Here, we synthesize published and unpublished pre- and post-outbreak measurements of key C cycle stocks and fluxes at GLEES. Multiple lines of evidence, including chamber measurements, eddy covariance measurements, and tracking of soil and forest floor C pools over time, point to the GLEES outbreak as a moderate-severity disturbance for C loss to the atmosphere, despite 70% to 80% of overstory tree death. Reductions in NEE were short-lived and the forest quickly returned to a carbon-neutral state, likely driven by an uptick in understory growth. Effect of mortality on the C cycle was asymmetrical, with a 50% reduction in net carbon uptake (NEE) two years into the outbreak, yet no measureable change in either ecosystem or growing season soil respiration. A small pulse in soil respiration occurred but was only detectable during the winter and amounted to < 10% of NEE. Possible reasons for the lack of measureable respiration response are discussed with emphasis on lessons learned for monitoring and modeling future outbreaks. We suggest a comprehensive assessment and definition of "moderate-severity" disturbances for Western forests and suggest that all tree mortality events may not be high-severity when it comes to C fluxes.

  16. Population dynamics at high Reynolds number

    NARCIS (Netherlands)

    Perlekar, P.; Benzi, R.; Nelson, D.R.; Toschi, F.

    2010-01-01

    We study the statistical properties of population dynamics evolving in a realistic two-dimensional compressible turbulent velocity field. We show that the interplay between turbulent dynamics and population growth and saturation leads to quasi-localization and a remarkable reduction in the carrying

  17. High Reynolds Number Liquid Flow Measurements

    Science.gov (United States)

    1988-08-01

    25. .n Fig. 25, the dotted line represents data taken from Eckelmann’s study in the thick viscous sublaver of an oil channel. Scatter in the...measurements of the fundamental physical quantities are not only an essencial part in an understanding of multiphase flows but also in the measurement process...technique. One of the most yloei’ used techniques, however, is some form of flow visualization. This includes the use o: tufts, oil paint films

  18. Who pays the price for high neuroticism? Moderators of longitudinal risks for depression and anxiety.

    Science.gov (United States)

    Vittengl, J R

    2017-07-01

    High neuroticism is a well-established risk for present and future depression and anxiety, as well as an emerging target for treatment and prevention. The current analyses tested the hypothesis that physical, social and socio-economic disadvantages each amplify risks from high neuroticism for longitudinal increases in depression and anxiety symptoms. A national sample of adults (n = 7108) provided structured interview and questionnaire data in the Midlife Development in the United States Survey. Subsamples were reassessed roughly 9 and 18 years later. Time-lagged multilevel models predicted changes in depression and anxiety symptom intensity across survey waves. High neuroticism predicted increases in a depression/anxiety symptom composite across retest intervals. Three disadvantage dimensions - physical limitations (e.g. chronic illness, impaired functioning), social problems (e.g. less social support, more social strain) and low socio-economic status (e.g. less education, lower income) - each moderated risks from high neuroticism for increases in depression and anxiety symptoms. Collectively, high scores on the three disadvantage dimensions amplified symptom increases attributable to high neuroticism by 0.67 standard deviations. In contrast, neuroticism was not a significant risk for increases in symptoms among participants with few physical limitations, few social problems or high socio-economic status. Risks from high neuroticism are not shared equally among adults in the USA. Interventions preventing or treating depression or anxiety via neuroticism could be targeted toward vulnerable subpopulations with physical, social or socio-economic disadvantages. Moreover, decreasing these disadvantages may reduce mental health risks from neuroticism.

  19. Moderate high fat diet increases sucrose self-administration in young rats.

    Science.gov (United States)

    Figlewicz, Dianne P; Jay, Jennifer L; Acheson, Molly A; Magrisso, Irwin J; West, Constance H; Zavosh, Aryana; Benoit, Stephen C; Davis, Jon F

    2013-02-01

    We have previously reported that a moderately high fat diet increases motivation for sucrose in adult rats. In this study, we tested the motivational, neurochemical, and metabolic effects of the high fat diet in male rats transitioning through puberty, during 5-8 weeks of age. We observed that the high fat diet increased motivated responding for sucrose, which was independent of either metabolic changes or changes in catecholamine neurotransmitter metabolites in the nucleus accumbens. However, AGRP mRNA levels in the hypothalamus were significantly elevated. We demonstrated that increased activation of AGRP neurons is associated with motivated behavior, and that exogenous (third cerebroventricular) AGRP administration resulted in significantly increased motivation for sucrose. These observations suggest that increased expression and activity of AGRP in the medial hypothalamus may underlie the increased responding for sucrose caused by the high fat diet intervention. Finally, we compared motivation for sucrose in pubertal vs. adult rats and observed increased motivation for sucrose in the pubertal rats, which is consistent with previous reports that young animals and humans have an increased preference for sweet taste, compared with adults. Together, our studies suggest that background diet plays a strong modulatory role in motivation for sweet taste in adolescent animals. Published by Elsevier Ltd.

  20. Monitoring Termite-Mediated Ecosystem Processes Using Moderate and High Resolution Satellite Imagery

    Science.gov (United States)

    Lind, B. M.; Hanan, N. P.

    2016-12-01

    Termites are considered dominant decomposers and prominent ecosystem engineers in the global tropics and they build some of the largest and architecturally most complex non-human-made structures in the world. Termite mounds significantly alter soil texture, structure, and nutrients, and have major implications for local hydrological dynamics, vegetation characteristics, and biological diversity. An understanding of how these processes change across large scales has been limited by our ability to detect termite mounds at high spatial resolutions. Our research develops methods to detect large termite mounds in savannas across extensive geographic areas using moderate and high resolution satellite imagery. We also investigate the effect of termite mounds on vegetation productivity using Landsat-8 maximum composite NDVI data as a proxy for production. Large termite mounds in arid and semi-arid Senegal generate highly reflective `mound scars' with diameters ranging from 10 m at minimum to greater than 30 m. As Sentinel-2 has several bands with 10 m resolution and Landsat-8 has improved calibration, higher radiometric resolution, 15 m spatial resolution (pansharpened), and improved contrast between vegetated and bare surfaces compared to previous Landsat missions, we found that the largest and most influential mounds in the landscape can be detected. Because mounds as small as 4 m in diameter are easily detected in high resolution imagery we used these data to validate detection results and quantify omission errors for smaller mounds.

  1. Moderate ethanol administration accentuates cardiomyocyte contractile dysfunction and mitochondrial injury in high fat diet-induced obesity.

    Science.gov (United States)

    Yuan, Fang; Lei, Yonghong; Wang, Qiurong; Esberg, Lucy B; Huang, Zaixing; Scott, Glenda I; Li, Xue; Ren, Jun

    2015-03-18

    Light to moderate drinking confers cardioprotection although it remains unclear with regards to the role of moderate drinking on cardiac function in obesity. This study was designed to examine the impact of moderate ethanol intake on myocardial function in high fat diet intake-induced obesity and the mechanism(s) involved with a focus on mitochondrial integrity. C57BL/6 mice were fed low or high fat diet for 16 weeks prior to ethanol challenge (1g/kg/d for 3 days). Cardiac contractile function, intracellular Ca(2+) homeostasis, myocardial histology, and mitochondrial integrity [aconitase activity and the mitochondrial proteins SOD1, UCP-2 and PPARγ coactivator 1α (PGC-1α)] were assessed 24h after the final ethanol challenge. Fat diet intake compromised cardiomyocyte contractile and intracellular Ca(2+) properties (depressed peak shortening and maximal velocities of shortening/relengthening, prolonged duration of relengthening, dampened intracellular Ca(2+) rise and clearance without affecting duration of shortening). Although moderate ethanol challenge failed to alter cardiomyocyte mechanical property under low fat diet intake, it accentuated high fat diet intake-induced changes in cardiomyocyte contractile function and intracellular Ca(2+) handling. Moderate ethanol challenge failed to affect fat diet intake-induced cardiac hypertrophy as evidenced by H&E staining. High fat diet intake reduced myocardial aconitase activity, downregulated levels of mitochondrial protein UCP-2, PGC-1α, SOD1 and interrupted intracellular Ca(2+) regulatory proteins, the effect of which was augmented by moderate ethanol challenge. Neither high fat diet intake nor moderate ethanol challenge affected protein or mRNA levels as well as phosphorylation of Akt and GSK3β in mouse hearts. Taken together, our data revealed that moderate ethanol challenge accentuated high fat diet-induced cardiac contractile and intracellular Ca(2+) anomalies as well as mitochondrial injury. Copyright

  2. Reynolds Number Scaling and Parameterization of Stratified Turbulent Wakes

    Science.gov (United States)

    2017-04-17

    be solved numerically. These issues are the focal point of our current investigations. The most recent update on our work on high Re effects in...Reynolds numbers, internal waves, nonlinear effects , mean flows, Lagrangian dispersion. 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT... location where nonlinear dynamics and, therefore, Lagrangian mean drift are most potent. An extensive existing database of 19 2-D simulations of

  3. Mutacins and bacteriocins like genes in Streptococcus mutans isolated from participants with high, moderate, and low salivary count.

    Science.gov (United States)

    Soto, Carolina; Padilla, Carlos; Lobos, Olga

    2017-02-01

    To detect S. mutans producers of mutacins and bacteriocins like substances (BLIS) from saliva of participants with low, moderate, and high salivary counts. 123 strains of S. mutans were obtained from participants with low, moderate, and high salivary counts (age 18 and 20 years old) and their antibacterial capacity analyzed. By using PCR amplification, the expression levels of mutacins and BLIS genes were studied (expressed in arbitrary units/ml) in all three levels. S. mutans strains from participants with low salivary counts show high production of mutacins (63%). In contrast, participants with moderate and high salivary counts depict relatively low levels of mutacins (22 and 15%, respectively). Moreover, participants with low salivary counts showed high expression levels of genes encoding mutacins, a result that correlates with the strong antimicrobial activity of the group. Participants with moderate and high salivary counts however depict low expression levels of mutacin related genes, and little antimicrobial activity. No BLIS were detected in any of the groups studied. S. mutans isolated from the saliva of participants with low bacterial counts have significant antibacterial capacity compared to that of participants with moderate and high salivary counts. The superior lethality of S. mutans in participants with low salivary counts is likely due to the augmented expression of mutacin- related genes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Cost-effectiveness of surveillance programs for families at high and moderate risk of hereditary non-polyposis colorectal cancer

    DEFF Research Database (Denmark)

    Olsen, Kim R.; Bojesen, Stig E.; Gerdes, Anne-Marie M.

    2007-01-01

    for the group at high risk. The aim of the present study is to determine cost-effectiveness of surveillance programs where families at both high and moderate risk of HNPCC participate. METHODS: A decision analytic model (Markov model) is developed to assess surveillance programs where families at high......OBJECTIVES: Surveillance programs are recommended to both families at high risk (Amsterdam-positive families with known- and unknown mutation) and moderate risk (families not fulfilling all Amsterdam criteria) of colorectal cancer (CRC). Cost-effectiveness has so far only been estimated...

  5. 76 FR 54801 - Reynolds Food Packaging LLC, a Subsidiary of Reynolds Group Holding Limited, Grove City, PA...

    Science.gov (United States)

    2011-09-02

    ... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-75,183] Reynolds Food Packaging LLC, a Subsidiary of Reynolds Group Holding Limited, Grove City, PA; Notice of Revised Determination... (TAA) applicable to workers and former workers of Reynolds Food Packaging LLC, a subsidiary of Reynolds...

  6. High-risk diagnosis, social stress, and parent-child relationships: A moderation model.

    Science.gov (United States)

    Bentley, Eryn; Millman, Zachary B; Thompson, Elizabeth; Demro, Caroline; Kline, Emily; Pitts, Steven C; DeVylder, Jordan E; Smith, Melissa Edmondson; Reeves, Gloria; Schiffman, Jason

    2016-07-01

    Stress is related to symptom severity among youth at clinical high-risk (CHR) for psychosis, although this relation may be influenced by protective factors. We explored whether the association of CHR diagnosis with social stress is moderated by the quality of parent-child relationships in a sample of 96 (36 CHR; 60 help-seeking controls) adolescents and young adults receiving mental health services. We examined self-reported social stress and parent-child relationships as measured by the Behavior Assessment System for Children, Second Edition (BASC-2), and determined CHR status from the clinician-administered Structured Interview for Psychosis-Risk Syndrome (SIPS). The social stress subscale, part of the clinical domain of the BASC-2, assesses feelings of stress and tension in personal relationships and the relations with parents subscale, part of the adaptive domain of the BASC-2, assesses perceptions of importance in family and quality of parent-child relationship. There was a modest direct relation between risk diagnosis and social stress. Among those at CHR, however, there was a significant relation between parent-child relationships and social stress (b=-0.73, t[92]=-3.77, psocial stress for those at risk for psychosis. Findings provide additional evidence to suggest that interventions that simultaneously target both social stress and parent-child relationships might be relevant for adolescents and young adults at clinical high-risk for psychosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Bullying victimization and student engagement in elementary, middle, and high schools: Moderating role of school climate.

    Science.gov (United States)

    Yang, Chunyan; Sharkey, Jill D; Reed, Lauren A; Chen, Chun; Dowdy, Erin

    2018-03-01

    Bullying is the most common form of school violence and is associated with a range of negative outcomes, including traumatic responses. This study used hierarchical linear modeling to examine the multilevel moderating effects of school climate and school level (i.e., elementary, middle, and high schools) on the association between bullying victimization and student engagement. Participants included 25,896 students in 4th to 12th grades from 114 schools. Results indicated that, after controlling for student and school demographic factors, positive school climate was associated with higher behavioral/cognitive and emotional engagement of students across all grades. This highlights the critical and fundamental role of positive school climate in bullying prevention and intervention, among students across all grade levels, including those with frequent bullying victimization experience. Results also showed that negative associations between student-level bullying victimization and engagement were intensified in more positive school climates. This finding suggests that, in comparison with students in schools with less positive school climates, the engagement of bullying victims in schools with a more positive school climate might be more negatively influenced by their victimization experience. Additionally, the relation between student-level bullying victimization and emotional engagement was significantly different across middle and high schools. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  8. Improvement of Reynolds-Stress and Triple-Product Lag Models

    Science.gov (United States)

    Olsen, Michael E.; Lillard, Randolph P.

    2017-01-01

    The Reynolds-stress and triple product Lag models were created with a normal stress distribution which was denied by a 4:3:2 distribution of streamwise, spanwise and wall normal stresses, and a ratio of r(sub w) = 0.3k in the log layer region of high Reynolds number flat plate flow, which implies R11(+)= [4/(9/2)*.3] approximately 2.96. More recent measurements show a more complex picture of the log layer region at high Reynolds numbers. The first cut at improving these models along with the direction for future refinements is described. Comparison with recent high Reynolds number data shows areas where further work is needed, but also shows inclusion of the modeled turbulent transport terms improve the prediction where they influence the solution. Additional work is needed to make the model better match experiment, but there is significant improvement in many of the details of the log layer behavior.

  9. [High versus moderate intense running exercise - effects on cardiometabolic risk-factors in untrained males].

    Science.gov (United States)

    Kemmler, Wolfgang; Lell, M; Scharf, M; Fraunberger, L; von Stengel, S

    2015-01-01

    Introduction | The philosophy on how to improve cardiometabolic risk factors most efficiently by endurance exercise is still controversial. To determine the effect of high-intensity (interval) training (HI[I]T) vs. moderate-intensity continuous exercise (MICE) training on cardiometabolic risk factors we conducted a 16-week crossover randomized controlled trial. Methods | 81 healthy untrained middle aged men were randomly assigned to a HI(I)T-group and a control-group that started the MICE running program after their control status. HI(I)T consisted of running exercise around or above the individual anaerobic threshold (≈ 80- 100 % HRmax); MICE focused on continuous running exercise at ≈ 65-77.5 % HRmax. Both protocols were comparable with respect to energy consumption. Study endpoints were cardiorespiratory fitness (VO2max), left ventricular mass index (LVMI), metabolic syndrome Z-score (MetS-Z-score), intima-media-thickness (IMT) and body composition. Results | VO2max-changes in this overweighed male cohort significantly (p=0.002) differ between HIIT (14.7 ± 9.3 %, p=0.001) and MICE (7.9 ± 7.4 %,p=0.001). LVMI, as determined via magnetic resonance imaging, significantly increased in both exercise groups (HIIT: 8.5 ± 5.4 %, p=0.001 vs. MICE: 5.3 ± 4.0 %, p=0.001), however the change was significantly more pronounced (p=0.005) in the HIIT-group. MetS-Z-score (HIIT: -2.06 ± 1.31, p=0.001 vs. MICE: -1.60 ± 1.77, p=0.001) and IMT (4.6 ± 5.9 % p=0.011 vs. 4.4 ± 8.1 %, p=0.019) did not show significant group-differences. Reductions of fat mass (-4.9 ± 9.0 %, p=0.010 vs. -9.5 ± 9.4, p=0.001) were significantly higher among the MICE-participants (p=0.034), however, the same was true (p=0.008) for lean body mass (0.5 ± 2.3 %, p=0.381 vs. -1.3 ± 2.0 %, p=0.003). Conclusion | In summary high-intensity interval training tends to impact cardiometabolic health more favorable compared with a moderate-intensity continuous endurance exercise protocol.

  10. The Variation of Slat Noise with Mach and Reynolds Numbers

    Science.gov (United States)

    Lockard, David P.; Choudhari, Meelan M.

    2011-01-01

    The slat noise from the 30P30N high-lift system has been computed using a computational fluid dynamics code in conjunction with a Ffowcs Williams-Hawkings solver. By varying the Mach number from 0.13 to 0.25, the noise was found to vary roughly with the 5th power of the speed. Slight changes in the behavior with directivity angle could easily account for the different speed dependencies reported in the literature. Varying the Reynolds number from 1.4 to 2.4 million resulted in almost no differences, and primarily served to demonstrate the repeatability of the results. However, changing the underlying hybrid Reynolds-averaged-Navier-Stokes/Large-Eddy-Simulation turbulence model significantly altered the mean flow because of changes in the flap separation. However, the general trends observed in both the acoustics and near-field fluctuations were similar for both models.

  11. Room Airflows with Low Reynolds Number Effects

    DEFF Research Database (Denmark)

    Topp, Claus; Nielsen, Peter V.; Davidson, Lars

    The behaviour of room airflows under fully turbulent conditions is well known both in terms of experiments and, numerical calculations by computational fluid dynamics (CFD). For room airflows where turbulence is not fully developed though, i.e. flows at low Reynolds numbers, the existing knowledge...... is limited. It has been the objective to investigate the behaviour of a plane isothermal wall jet in a full-scale ventilated room at low Reynolds numbers, i.e. when the flow is not fully turbulent. The results are significantly different from known theory for fully turbulent flows. It was found that the jet...... constants are a strong function of the Reynolds number up to a level of Reh≈500....

  12. Fully developed MHD turbulence near critical magnetic Reynolds number

    International Nuclear Information System (INIS)

    Leorat, J.; Pouquet, A.; Frisch, U.

    1981-01-01

    Liquid-sodium-cooled breeder reactors may soon be operating at magnetic Reynolds numbers Rsup(M) where magnetic fields can be self-excited by a dynamo mechanism. Such flows have kinetic Reynolds numbers Rsup(V) of the order of 10 7 and are therefore highly turbulent. The behaviour of MHD turbulence with high Rsup(V) and low magnetic Prandtl numbers is investigated, using the eddy-damped quasi-normal Markovian closure applied to the MHD equations. For simplicity the study is restricted to homogeneous and isotropic turbulence, but includes helicity. A critical magnetic Reynolds number Rsub(c)sup(M) of the order of a few tens (non-helical case) is obtained above which magnetic energy is present. Rsub(c)sup(M) is practically independent of Rsup(V) (in the range 40 to 10 6 ) and can be considerably decreased by the presence of helicity. No attempt is made to obtain quantitative estimates for a breeder reactor, but discuss some of the possible consequences of exceeding Rsub(c)sup(M) such as decreased turbulent heat transport. (author)

  13. Numerical study of circular synthetic jets at low Reynolds numbers

    International Nuclear Information System (INIS)

    Xia, Qingfeng; Lei, Shenghui; Ma, Jieyan; Zhong, Shan

    2014-01-01

    Highlights: • Parameter maps depicting different flow regimes of synthetic jets are produced. • Boundaries separating these regimes are defined using quantitative criteria. • The Reynolds number is most appropriate for classifying different flow regimes. • A use of high suction cycle factors enhances the effectiveness of synthetic jets. - Abstract: In this paper, the flow patterns of circular synthetic jets issuing into a quiescent flow at low Reynolds numbers are studied numerically. The results confirm the presence of the three jet flow regimes, i.e. no jet formation, jet flow without rollup and jet flow with rollup reported in the literature. The boundaries of the different jet flow regimes are determined by tracking the structures produced by the synthetic jets in the near field of the jet orifice over several actuation cycles and examining the cycle-averaged streamwise velocity profiles along the jet central axis. When the Stokes number is above a certain threshold value appropriate for the corresponding flow regime, a good correlation between the flow patterns and the jet Reynolds number defined using the jet orifice diameter, Re Do , is also found. Furthermore, the flow structures of synthetic jets with different suction duty cycle factors are compared. The use of a high suction duty cycle factor strengthens the synthetic jet resulting in a greater penetration depth into the surrounding fluid. Overall, the finding from this study enables the flow regimes, in which a synthetic jet actuator with a circular orifice operates, to be determined. It also provides a way of designing more effective synthetic jet actuators for enhancing mass and momentum transfer at very low Reynolds numbers

  14. Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows

    KAUST Repository

    Scribano, Gianfranco

    2016-12-29

    The counterflow configuration is a canonical stagnation flow, featuring two opposed impinging round jets and a mixing layer across the stagnation plane. Although counterflows are used extensively in the study of reactive mixtures and other applications where mixing of two streams is required, quantitative data on the scaling properties of the flow field are lacking. The aim of this work is to characterize the velocity and mixing fields in isothermal counterflows over a wide range of conditions. The study features both experimental data from particle image velocimetry and results from detailed axisymmetric simulations. The scaling laws for the nondimensional velocity and mixture fraction are obtained as a function of an appropriate Reynolds number and the ratio of the separation distance of the nozzles to their diameter. In the range of flow configurations investigated, the nondimensional fields are found to depend primarily on the separation ratio and, to a lesser extent, the Reynolds number. The marked dependence of the velocity field with respect to the separation ratio is linked to a high pressure region at the stagnation point. On the other hand, Reynolds number effects highlight the role played by the wall boundary layer on the interior of the nozzles, which becomes less important as the separation ratio decreases. The normalized strain rate and scalar dissipation rate at the stagnation plane are found to attain limiting values only for high values of the Reynolds number. These asymptotic values depend markedly on the separation ratio and differ significantly from the values produced by analytical models. The scaling of the mixing field does not show a limiting behavior as the separation ratio decreases to the smallest practical value considered.

  15. The Effect of a Moderately Low and High Carbohydrate Intake on Crossfit Performance.

    Science.gov (United States)

    Escobar, Kurt A; Morales, Jacobo; Vandusseldorp, Trisha A

    2016-01-01

    CrossFit is a metabolically demanding strength and conditioning method which performance may benefit from a carbohydrate (CHO)-rich diet. This study investigated the effect of three consecutive days of high CHO intake on CrossFit performance and corresponding metabolically -related variables in strength trained individuals. Eighteen subjects with a CHO intake of CrossFit workout. Oxygen consumption (VO 2 ), respiratory exchange ratio (RER), and blood lactate (BL) were also measured. Days 6-8, the CHO group increased CHO intake from CrossFit workouts followed by a day of rest prior to day 9. There was a significant increase in repetitions completed in both groups in day 9 (vs. means score of day 1 + 5) (p = 0.002), but no differences between C and CHO groups (p = 0.111). However, the CHO group displayed a 15.2 repetition increase (+10.9%) in day 9, compared to 5.7 (+4.2%) by the C group. VO 2 , RER, and BL were not influenced by the experimental intervention. Our results suggest that the CrossFit-embraced practice of moderately-low CHO diets may be adequate in CHO during short periods of training, however, given the noted trend, extended training periods may be effected.

  16. Simplified static method for determining seismic loads on equipment in moderate and high hazard facilities

    International Nuclear Information System (INIS)

    Scott, M.A.; Holmes, P.A.

    1991-01-01

    A simplified static analysis methodology is presented for qualifying equipment in moderate and high-hazard facility-use category structures, where the facility use is defined in Design and Evaluation Guidelines for Department of Energy Facilities Subjected to Natural Phenomena Hazards, UCRL-15910. Currently there are no equivalent simplified static methods for determining seismic loads on equipment in these facility use categories without completing dynamic analysis of the facility to obtain local floor accelerations or spectra. The requirements of UCRL-15910 specify the use of open-quotes dynamicclose quotes analysis methods, consistent with Seismic Design Guidelines for Essential Buildings, Chapter 6, open-quotes Nonstructural Elements,close quotes TM5-809-10-1, be used for determining seismic loads on mechanical equipment and components. Chapter 6 assumes that the dynamic analysis of the facility has generated either floor response spectra or model floor accelerations. These in turn are utilized with the dynamic modification factor and the actual demand and capacity ratios to determine equipment loading. This complex methodology may be necessary to determine more exacting loads for hard to qualify equipment but does not provide a simple conservative loading methodology for equipment with ample structural capacity

  17. Femtosecond (FS) laser vision correction procedure for moderate to high myopia

    DEFF Research Database (Denmark)

    Vestergaard, Anders Højslet; Ivarsen, Anders; Asp, Sven

    2013-01-01

    Purpose:  To present our initial clinical experience with ReLEx(®) flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher-order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS-LASIK). Methods:  Prospective study of ReLEx compared...... with a retrospective study of FS-LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS-LASIK patients were retrospectively identified. Visual acuity, spherical...... equivalent (SE) and corneal tomography were measured before and 3 months after surgery. Results:  Preoperative SE averaged -7.50 ± 1.16 D (ReLEx) and -7.32 ± 1.09 D (FS-LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction...

  18. Cosmic evolution of AGN with moderate-to-high radiative luminosity in the COSMOS field

    Science.gov (United States)

    Ceraj, L.; Smolčić, V.; Delvecchio, I.; Delhaize, J.; Novak, M.

    2018-05-01

    We study the moderate-to-high radiative luminosity active galactic nuclei (HLAGN) within the VLA-COSMOS 3 GHz Large Project. The survey covers 2.6 square degrees centered on the COSMOS field with a 1σ sensitivity of 2.3 μJy/beam across the field. This provides the simultaneously largest and deepest radio continuum survey available to date with exquisite multi-wavelength coverage. The survey yields 10,830 radio sources with signal-to-noise ratios >=5. A subsample of 1,604 HLAGN is analyzed here. These were selected via a combination of X-ray luminosity and mid-infrared colors. We derive luminosity functions for these AGN and constrain their cosmic evolution out to a redshift of z ~ 6, for the first time decomposing the star formation and AGN contributions to the radio continuum emission in the AGN. We study the evolution of number density and luminosity density finding a peak at z ~ 1.5 followed by a decrease out to a redshift z ~ 6.

  19. Development of Probabilistic Design Basis Earthquake (DBE) Parameters for Moderate and High Hazard Facilities at INEEL

    International Nuclear Information System (INIS)

    Payne, S. M.; Gorman, V. W.; Jensen, S. A.; Nitzel, M. E.; Russell, M. J.; Smith, R. P.

    2000-01-01

    Design Basis Earthquake (DBE) horizontal and vertical response spectra are developed for moderate and high hazard facilities or Performance Categories (PC) 3 and 4, respectively, at the Idaho National Engineering and Environmental Laboratory (INEEL). The probabilistic DBE response spectra will replace the deterministic DBE response spectra currently in the U.S. Department of Energy Idaho Operations Office (DOE-ID) Architectural Engineering Standards that govern seismic design criteria for several facility areas at the INEEL. Probabilistic DBE response spectra are recommended to DOE Naval Reactors for use at the Naval Reactor Facility at INEEL. The site-specific Uniform Hazard Spectra (UHS) developed by URS Greiner Woodward Clyde Federal Services are used as the basis for developing the DBE response spectra. In 1999, the UHS for all INEEL facility areas were recomputed using more appropriate attenuation relationships for the Basin and Range province. The revised UHS have lower ground motions than those produced in the 1996 INEEL site-wide probabilistic ground motion study. The DBE response spectra were developed by incorporating smoothed broadened regions of the peak accelerations, velocities, and displacements defined by the site-specific UHS. Portions of the DBE response spectra were adjusted to ensure conservatism for the structural design process

  20. Experimental investigation of moderately high temperature water source heat pump with non-azeotropic refrigerant mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shengjun; Wang, Huaixin; Guo, Tao [Department of Thermal Energy and Refrigeration Engineering, School of Mechanical Engineering, Tianjin University, Tianjin 300072 (China)

    2010-05-15

    Experimental investigations were carried out on non-azeotropic refrigerant mixtures, named M1A (mass fraction of 20%R152a and 80%R245fa), M1B (mass fraction of 37% R152a and 63%R245fa) and M1C (mass fraction of 50%R152a and 50%R245fa), based on a water-to-water heat pump system in the condensing temperature range of 70-90 C with a cycle temperature lift of 45 C. Performance of R245fa was tested for comparison. Unfair factors in experimental comparative evaluation research with the same apparatus were identified and corrected. Experimental cycle performance of the mixtures were tested and compared with improved experimental assessment methodology. The results show that all of the mixtures deliver higher discharge temperature, higher heating capacity, higher COP and higher {epsilon}{sub h,c} than R245fa. M1B presents the most excellent cycle performance and is recommended as working fluid for moderate/high temperature heat pump. (author)

  1. INTACS before or after laser in situ keratomileusis: correction of thin corneas with moderately high myopia.

    Science.gov (United States)

    Ito, Mitsutoshi; Arai, Hiroyuki; Fukumoto, Teruki; Toda, Ikuko; Tsubota, Kazuo

    2004-01-01

    Intrastromal corneal ring segments (INTACS Micro-Thin Prescription Inserts by Addition Technologies, Fremont, Calif) were inserted as a combined surgery with laser in situ keratomileusis (LASIK) in six eyes with thin corneas to correct moderately high myopia. INTACS were implanted before LASIK (INTACS-LASIK) in three eyes and after LASIK (LASIK-INTACS) in three eyes. Mean preoperative manifest spherical equivalent refraction was -7.88 diopters. Mean follow-up was 306 days. No intraoperative complications occurred. The LASIK-INTACS eyes were slightly more overcorrected than the INTACS-LASIK eyes because of the enhanced performance of INTACS in the thinned corneal tissue. Induced astigmatism by INTACS per se was less in the LASIK-INTACS eyes than in the INTACS-LASIK eyes. At last examination, uncorrected visual acuity was better than 20/25 in all eyes. Best spectacle-corrected visual acuity was within 1 line of the preoperative value in all eyes. Both methods resulted in significant improvement in visual acuity and refraction. Based on our limited experience, however, LASIK followed by INTACS is preferred for reasons of safety, convenience, and lower induced cylinder.

  2. [The effect of 24 weeks of moderate-to-high intensity strength training on the elderly].

    Science.gov (United States)

    Solà Serrabou, Marta; López del Amo, José Luis; Valero, Oliver

    2014-01-01

    Strength programs have been seen to be useful in minimizing the effects of sarcopenia, although intervention protocols may vary in their content and characteristics. The aim of this study was to demonstrate the influence of a particular strength protocol for the elderly. A total of 35 individuals took part in the study, with 18 in the exercise group (4 men and 14 women), and 17 in the control group (4 men and 13 women). The average age was 73. The exercise group carried out a strength training program at moderate to high intensity over 24 weeks. Strength was evaluated using the chair stand test, 2-minute step and 2 vertical jumps-squat jump (SJ), and countermovement jump (CMJ). Falls in both groups were also compared before and after the intervention, as well as their relationship with the chair stand variable. A tendency towards improvement was observed in all tests, with the exception of CMJ; while the control group showed a tendency in the opposite direction. Contrast between the two groups at the end of the intervention was notable in all the tests. An inverse relationship between the chair stand strength variable and the number of falls was evident. According to the results achieved, the training was perceived to exercise a positive influence on both the strength of the elderly people and a reduction of the number of falls. The gap between the two groups widened towards the end of the intervention. Copyright © 2013 SEGG. Published by Elsevier Espana. All rights reserved.

  3. High intensity intermittent games-based activity and adolescents' cognition: moderating effect of physical fitness.

    Science.gov (United States)

    Cooper, Simon B; Dring, Karah J; Morris, John G; Sunderland, Caroline; Bandelow, Stephan; Nevill, Mary E

    2018-05-08

    An acute bout of exercise elicits a beneficial effect on subsequent cognitive function in adolescents. The effect of games-based activity, an ecologically valid and attractive exercise model for young people, remains unknown; as does the moderating effect of fitness on the acute exercise-cognition relationship. Therefore, the aim of the present study was to examine the effect of games-based activity on subsequent cognition in adolescents, and the moderating effect of fitness on this relationship. Following ethical approval, 39 adolescents (12.3 ± 0.7 year) completed an exercise and resting trial in a counterbalanced, randomised crossover design. During familiarisation, participants completed a multi-stage fitness test to predict VO 2 peak. The exercise trial consisted of 60-min games-based activity (basketball), during which heart rate was 158 ± 11 beats∙min - 1 . A battery of cognitive function tests (Stroop test, Sternberg paradigm, trail making and d2 tests) were completed 30-min before, immediately following and 45-min following the basketball. Response times on the complex level of the Stroop test were enhanced both immediately (p = 0.021) and 45-min (p = 0.035) post-exercise, and response times on the five item level of the Sternberg paradigm were enhanced immediately post-exercise (p = 0.023). There were no effects on the time taken to complete the trail making test or any outcome of the d2 test. In particular, response times were enhanced in the fitter adolescents 45-min post-exercise on both levels of the Stroop test (simple, p = 0.005; complex, p = 0.040) and on the three item level of the Sternberg paradigm immediately (p = 0.017) and 45-min (p = 0.008) post-exercise. Games-based activity enhanced executive function and working memory scanning speed in adolescents, an effect particularly evident in fitter adolescents, whilst the high intensity intermittent nature of games-based activity may be too demanding for

  4. IMPACT OF TROPICAL CONDITIONS ON THIN-LAYER CHROMATOGRAPHY IN ANALYTICAL TOXICOLOGY - HIGH-TEMPERATURES AND MODERATE HUMIDITIES

    NARCIS (Netherlands)

    DEZEEUW, RA; FRANKE, JP; DIK, E; TENDOLLE, W; KAM, BL

    The impact of high temperatures (24 to 39-degrees-C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were

  5. Comparison of Moderate and High Energy of a Nano-Fractional Radiofrequency Treatment on a Photoaging Hairless Mice Model.

    Science.gov (United States)

    Sun, Wenjia; Zhang, Chengfeng; Zhao, Juemin; Wu, Jiaqiang; Xiang, Leihong

    2018-04-01

    Fractional radiofrequency (FRF) has been widely used in skin rejuvenation. To explore optimal settings, it is important to compare different treatment parameters. This study was designed to compare the effect of moderate-energy and high-energy FRF treatment on a hairless mice model. Fifteen photoaged hairless mice were assigned to 3 groups: control, moderate energy, and high energy. Two treatment sessions (T × 1 and T × 2) were performed at 1-month interval. Transepidermal water loss was measured at baseline, immediately, 1, 2, and 4 weeks after T × 1. Skin samples were harvested before each treatment, 1 and 2 months after T × 2. Neocollagenesis was evaluated by hematoxylin and eosin staining, Masson staining, and immunohistochemistry analysis. Transepidermal water loss of high-energy group was significantly higher than the moderate-energy group (p = .008) immediately after T × 1. Remarkable fibroblast proliferation was observed at 1 month after T × 1, followed by significant dermal thickening, and increase of Type I collagen and Type III collagen. There was no significant difference between 2 energy groups in fibroblast proliferation, dermal thickness, and collagen density. The effect of moderate-energy treatment was comparable with that of high energy in neocollagenesis, whereas moderate energy yielded less damage to skin barrier function.

  6. Moderate Bravery

    DEFF Research Database (Denmark)

    Majgaard, Klaus

    2016-01-01

    Purpose: The ability to act in a purposeful and effective way amid institutional tensions and paradoxes is, right now, a highly prized quality in public leadership. The purpose of this chapter is to qualify moderately brave acts as a learning format that combines the analytical and performative...

  7. Startup of a high-temperature reactor cooled and moderated by supercritical-pressure light water

    International Nuclear Information System (INIS)

    Yi, Tin Tin; Ishiwatari, Yuki; Koshizuka, Seiichi; Oka, Yoshiaki

    2003-01-01

    The startup schemes of high-temperature reactors cooled and moderated by supercritical pressure light water (SCLWR-H) with square lattice and descending flow type water rods are studied by thermal-hydraulic analysis. In this study, two kinds of startup systems are investigated. In the constant pressure startup system, the reactor starts at a supercritical pressure. A flash tank and pressure reducing valves are necessary. The flash tank is designed so that the moisture content in the steam is less than 0.1%. In sliding pressure startup system, the reactor starts at a subcritical pressure. A steam-water separator and a drain tank are required for two-phase flow at startup. The separator is designed by referring to the water separator used in supercritical fossil-fired power plants. The maximum cladding surface temperature during the power-raising phase of startup is restricted not to exceed the rated value of 620degC. The minimum feedwater flow rate is 25% for constant pressure startup and 35% for sliding pressure startup system. It is found that both constant pressure startup system and sliding pressure startup system are feasible in SCLWR-H from the thermal hydraulic point of view. The core outlet temperature as high as 500degC can be achieved in the present design of SCLWR-H. Since the feedwater flow rate of SCLWR-H (1190 kg/s) is lower than that of the previous SCR designs the weight of the component required for startup is reduced. The sliding pressure startup system is better than constant pressure startup system in order to reduce the required component weight (and hence material expenditure) and to simplify the startup plant system. (author)

  8. [Moderate exercise and intake of either high or low glycemic index carbohydrates in sedentary women].

    Science.gov (United States)

    Ortiz-Rodríguez, Briseidy; De León, Lidia G; Esparza-Romero, Julián; Carrasco-Legleu, Claudia E; Candia-Luján, Ramón

    2018-05-25

    To analyze changes in blood glucose, insulin and triglyceride concentrations in relation to a moderate aerobic exercise in sedentary women of different body weight, exposed to either a high or low glycemic index carbohydrates diet. DISEñO: Cross-over type. SITE: Research was performed in the Exercise Physiology Laboratory at Facultad de Ciencias de la Cultura Física, Universidad Autónoma de Chihuahua, México. Twenty-six young sedentary women who did not exercise in the last year participated in the study. Four of adequate weight (AW) and 2 with obesity (OB) were excluded for not consuming the suggested carbohydrates (1gr/kg of weight) nor completed the programed exercise. There were n=10 in each group (AW/OB). Two treatments of 55minutes of aerobic exercise each were applied one day after consuming either high or low glycemic index carbohydrates. Plasmatic glucose, insulin, and triglycerides were determined before and after the scheduled exercise. Glucose, insulin, and triglycerides were higher in OB than in AW at baseline. Glucose was normalized in OB from 5.8±0.35 to 5.3±0.23 mmol/L (P=.001), only by eating foods with low glycemic index; triglycerides increased from 139.5±66.0 to 150.8±67.2mg/dl (P=.004) at the end of the exercise, after consumption of low glycemic index carbohydrates. Elevation of triglycerides secondary to exercise after consumption of low glycemic index seems to indicate an increase of lipid oxidation in OB. Copyright © 2018 The Authors. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. Cloud detection method for Chinese moderate high resolution satellite imagery (Conference Presentation)

    Science.gov (United States)

    Zhong, Bo; Chen, Wuhan; Wu, Shanlong; Liu, Qinhuo

    2016-10-01

    Cloud detection of satellite imagery is very important for quantitative remote sensing research and remote sensing applications. However, many satellite sensors don't have enough bands for a quick, accurate, and simple detection of clouds. Particularly, the newly launched moderate to high spatial resolution satellite sensors of China, such as the charge-coupled device on-board the Chinese Huan Jing 1 (HJ-1/CCD) and the wide field of view (WFV) sensor on-board the Gao Fen 1 (GF-1), only have four available bands including blue, green, red, and near infrared bands, which are far from the requirements of most could detection methods. In order to solve this problem, an improved and automated cloud detection method for Chinese satellite sensors called OCM (Object oriented Cloud and cloud-shadow Matching method) is presented in this paper. It firstly modified the Automatic Cloud Cover Assessment (ACCA) method, which was developed for Landsat-7 data, to get an initial cloud map. The modified ACCA method is mainly based on threshold and different threshold setting produces different cloud map. Subsequently, a strict threshold is used to produce a cloud map with high confidence and large amount of cloud omission and a loose threshold is used to produce a cloud map with low confidence and large amount of commission. Secondly, a corresponding cloud-shadow map is also produced using the threshold of near-infrared band. Thirdly, the cloud maps and cloud-shadow map are transferred to cloud objects and cloud-shadow objects. Cloud and cloud-shadow are usually in pairs; consequently, the final cloud and cloud-shadow maps are made based on the relationship between cloud and cloud-shadow objects. OCM method was tested using almost 200 HJ-1/CCD images across China and the overall accuracy of cloud detection is close to 90%.

  10. The effects of moderately high temperature on zeaxanthin accumulation and decay.

    Science.gov (United States)

    Zhang, Ru; Kramer, David M; Cruz, Jeffrey A; Struck, Kimberly R; Sharkey, Thomas D

    2011-09-01

    Moderately high temperature reduces photosynthetic capacities of leaves with large effects on thylakoid reactions of photosynthesis, including xanthophyll conversion in the lipid phase of the thylakoid membrane. In previous studies, we have found that leaf temperature of 40°C increased zeaxanthin accumulation in dark-adapted, intact tobacco leaves following a brief illumination, but did not change the amount of zeaxanthin in light-adatped leaves. To investigate heat effects on zeaxanthin accumulation and decay, zeaxanthin level was monitored optically in dark-adapted, intact tobacco and Arabidopsis thaliana leaves at either 23 or 40°C under 45-min illumination. Heated leaves had more zeaxanthin following 3-min light but had less or comparable amounts of zeaxanthin by the end of 45 min of illumination. Zeaxanthin accumulated faster at light initiation and decayed faster upon darkening in leaves at 40°C than leaves at 23°C, indicating that heat increased the activities of both violaxanthin de-epoxidase (VDE) and zeaxanthin epoxidase (ZE). In addition, our optical measurement demonstrated in vivo that weak light enhances zeaxanthin decay relative to darkness in intact leaves of tobacco and Arabidopsis, confirming previous observations in isolated spinach chloroplasts. However, the maximum rate of decay is similar for weak light and darkness, and we used the maximum rate of decay following darkness as a measure of the rate of ZE during steady-state light. A simulation indicated that high temperature should cause a large shift in the pH dependence of the amount of zeaxanthin in leaves because of differential effects on VDE and ZE. This allows for the reduction in ΔpH caused by heat to be offset by increased VDE activity relative to ZE.

  11. The neurological legacy of John Russell Reynolds (1828-1896).

    Science.gov (United States)

    Eadie, M J

    2007-04-01

    Sir John Russell Reynolds was an eminent and highly influential physician in the Victorian era who held the Presidencies of the Royal College of Physicians of London, and of the British Medical Association. He was the protégée of the great experimental physiologist, Marshall Hall, who discovered the reflex arc, and succeeded to Hall's clinical practice in London. Reynolds' thought and clinical activities linked the emerging British neurology of the first half of the 19th century with its blossoming, particularly in London, from 1860 onwards. In his writings Reynolds was the first English author to apply the approach to classification of neurological disorders that is still often used, though now in modified form. He was also the first to enunciate the notion of positive and negative symptoms arising from neurological disease and to suggest their pathogenesis, and was arguably the originator of the influential concept that an idiopathic disease, epilepsy, existed, one to be distinguished from 'epileptiform' seizures due to brain pathology.

  12. Response study of fission track detectors using two different moderator designs in a high-energy radiation field

    International Nuclear Information System (INIS)

    Mayer, S.; Boschung, M.; Fiechtner, A.; Fuerstner, M.; Wernli, C.

    2008-01-01

    Fission track detectors in the center of moderating spheres are routinely used to measure the ambient dose equivalent due to neutrons in the environmental dosimetry at Paul Scherrer Institut (PSI). Originally, the system was designed to cope with neutrons from skyshine effects. Later, the system was also adapted behind the shielding of PSI's accelerators. Nowadays, as a consequence of continuously upgrading accelerator energies and intensities, the neutron energy behind thick shielding can range from fractions of eV to about 1 GeV (e.g. at CERN). For this reason a measurement campaign in a high-energy stray radiation field at CERN's High-Energy Reference Field Facility (CERF) was initiated to study and compare the response of the already existing detector-moderator configuration and a new design, the 'GSI ball'. Employing an additional lead layer in a moderator sphere of 32.5 cm diameter, the GSI ball was primarily designed for the use with thermoluminescent based dosimeters in its center in order to optimize the response for the measurement of H*(10) to higher neutron energies. In this work, the measurement results for fission track detectors using two different radiator materials in the PSI and the GSI moderator are presented. Based on these studies, on the one hand, field calibration factors for the use in presumably similar high-energy fields around accelerators could be deduced. On the other hand, it could be shown that there is no need to replace the established PSI moderator by the GSI moderator since the combination of fission track detector and GSI moderator does not result in a significant sensitivity improvement

  13. Response study of fission track detectors using two different moderator designs in a high-energy radiation field

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, S. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)], E-mail: Sabine.Mayer@psi.ch; Boschung, M.; Fiechtner, A. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Fuerstner, M. [CERN, CH-1211 Geneva 23 (Switzerland); Wernli, C. [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2008-02-15

    Fission track detectors in the center of moderating spheres are routinely used to measure the ambient dose equivalent due to neutrons in the environmental dosimetry at Paul Scherrer Institut (PSI). Originally, the system was designed to cope with neutrons from skyshine effects. Later, the system was also adapted behind the shielding of PSI's accelerators. Nowadays, as a consequence of continuously upgrading accelerator energies and intensities, the neutron energy behind thick shielding can range from fractions of eV to about 1 GeV (e.g. at CERN). For this reason a measurement campaign in a high-energy stray radiation field at CERN's High-Energy Reference Field Facility (CERF) was initiated to study and compare the response of the already existing detector-moderator configuration and a new design, the 'GSI ball'. Employing an additional lead layer in a moderator sphere of 32.5 cm diameter, the GSI ball was primarily designed for the use with thermoluminescent based dosimeters in its center in order to optimize the response for the measurement of H*(10) to higher neutron energies. In this work, the measurement results for fission track detectors using two different radiator materials in the PSI and the GSI moderator are presented. Based on these studies, on the one hand, field calibration factors for the use in presumably similar high-energy fields around accelerators could be deduced. On the other hand, it could be shown that there is no need to replace the established PSI moderator by the GSI moderator since the combination of fission track detector and GSI moderator does not result in a significant sensitivity improvement.

  14. The different effects of high intensity interval training and moderate intensity interval training for weightlessness countermeasures

    Science.gov (United States)

    Wang, Lin-Jie; Cheng, Tan; Zhi-Li, Li; Hui-juan, Wang; Wen-juan, Chen; Jianfeng, Zhang; Desheng, Wang; Dongbin, Niu; Qi, Zhao; Chengjia, Yang; Yanqing, Wang

    High intensity interval training (HIIT) has been demonstrated to improve performance in a relatively short training period. But the difference between high intensity interval training and moderate intensity interval training (MIIT) in simulated weightlessness still has not been well studied. This study sought to characterize the difference between 6 weeks high intensity interval training and moderate intensity interval training under reduced weight (RW) gait training device and zero-gravity locomotion system (ZLS). Twenty-three subjects (14M/4F, 32.5±4.5 years) volunteered to participate. They were divided into three groups, that were MITT (alternating 2 min at 40% VO _{2} peak and 2 min at 60% VO _{2} peak for 30min, five days per week) RW group (n=8), HITT (alternating 2 min at 40% VO _{2} peak and 2 min at 90% VO _{2} peak for 30min, three days per week) RW group (n=8) and HITT ZLS group (n=7). The Z-axis load used in RW group was 80% body weight (BW) and in ZLS was 100% BW. Cardiopulmonary function was measured before, after 4-week training and after 6-week training. Isokinetic knee extension-flexion test at 60(°) deg/s and 180(°) deg/s were performed before and after the 6-week training, and isometric knee extension-flexion test at 180(°) deg/s was also examined at the same time. It was found that the VO _{2} peaks, metabolic equivalent (MET), Speedmax and respiratory exchange ratio (RER) were significantly increased after 4 and 6-week training in all three groups and no significant group difference were detected. The peak torque at 60(°) deg/s for right knee flexion were significantly increased after 6 week-training in all three groups, and only in HITT RW group the total power at 60(°) deg/s for right knee flexion enhanced. The total power and average power at 60(°) deg/s for right knee extension decreased significantly after 6-week training in all three groups. The peak torque at 60(°) deg/s for right knee extension in MIIT RW group was

  15. The moderator's moderator

    International Nuclear Information System (INIS)

    Williamson, G.K.

    1990-01-01

    A brief account is given of the development of graphite moderators for Magnox and advanced gas cooled reactors. The accident at Windscale in 1957 brought to worldwide attention the importance of irradiation damage in graphite and the consequent storage of Wigner energy. In spite of the Windscale setback, preparations for the civil programme of Magnox reactors went ahead apace. Some of the background to the disastrous Dungeness B tender is presented. In spite of all the difficulties and uncertainties, the graphite in UK reactors has performed well. In all cases, as far as the author is aware, the behaviour of the graphite moderators will not prevent design life being achieved. (author)

  16. Safety analysis of high temperature reactor cooled and moderated by supercritical light water

    International Nuclear Information System (INIS)

    Ishiwatari, Yuki; Oka, Yoshiaki; Koshizuka, Seiichi

    2003-01-01

    This paper describes 'Safety' of a high temperature supercritical light water cooled and moderated reactor (SCRLWR-H) with descending flow water rods. The safety system of the SCLWR-H is similar to that of a BWR. It consists of reactor scram, high pressure auxiliary feedwater system (AFS), low pressure core injection system (LPCI), safety relief valves (SRV), automatic depressurization system (ADS), and main steam isolation valves (MSIV). Ten types of transients and five types of accidents are analyzed using a plant transient analysis code SPRAT-DOWN. The sequences are determined referring to LWRs. At the 'Loss of load without turbine bypass' transient, the coolant density and the core power are increased by the over-pressurization, and at the same time the core flow rate is decreased by the closure of the turbine control valves. The peak cladding temperature increases to 727degC. The high temperature at this type of transient is one of the characteristics of the SCLWR-H. Conversely at 'feedwater-loss' events, the core power decrease to some extend by density feedback before the reactor scram. The peak cladding temperatures at the 'Partial loss of feedwater' transient and the 'Total loss of feedwater' accident are only 702degC and 833degC, respectively. The cladding temperature does not increase so much at the transients 'Loss of feedwater heating' and 'CR withdrawal' because of the operation of the plant control system. All the transients and accidents satisfy the satisfy criteria with good margins. The highest cladding temperatures of the transients and the accidents are 727degC and 833degC at the 'Loss of load without turbine bypass' and 'Total loss of feedwater', respectively. The duration of the high cladding temperature is very short at the transients. According to the parametric survey, the peak cladding temperature are sensitive to the parameters such as the pump coast-down time, delay of pump trip, AFS capacity, AFS delay, CR worth, and SRV setpoint

  17. Does moderate-to-high intensity Nordic walking improve functional capacity and pain in fibromyalgia? A prospective randomized controlled trial

    OpenAIRE

    Mannerkorpi, Kaisa; Nordeman, Lena; Cider, ?sa; Jonsson, Gunilla

    2010-01-01

    Introduction The objective of this study was to investigate the effects of moderate-to-high intensity Nordic walking (NW) on functional capacity and pain in fibromyalgia (FM). Methods A total of 67 women with FM were recruited to the study and randomized either to moderate-to-high intensity Nordic Walking (n = 34, age 48 ? 7.8 years) or to a control group engaging in supervised low-intensity walking (LIW, n = 33, age 50 ? 7.6 years). Primary outcomes were the six-minute walk test (6MWT) and t...

  18. Boundary induced nonlinearities at small Reynolds numbers

    NARCIS (Netherlands)

    Sbragaglia, M.; Sugiyama, K.

    2007-01-01

    We investigate the importance of boundary slip at finite Reynolds numbers for mixed boundary conditions. Nonlinear effects are induced by the non-homogeneity of the boundary condition and change the symmetry properties of the flow with an overall mean flow reduction. To explain the observed drag

  19. Revised Reynolds Stress and Triple Product Models

    Science.gov (United States)

    Olsen, Michael E.; Lillard, Randolph P.

    2017-01-01

    Revised versions of Lag methodology Reynolds-stress and triple product models are applied to accepted test cases to assess the improvement, or lack thereof, in the prediction capability of the models. The Bachalo-Johnson bump flow is shown as an example for this abstract submission.

  20. Reynold-Number Effects on Near-Wall Turbulence

    Science.gov (United States)

    Mansour, N. N.; Kim, J.; Moser, R. D.; Rai, Man Mohan (Technical Monitor)

    1995-01-01

    The Reynolds stress budget in a full developed turbulent channel flow for three Reynolds numbers (Re = 180,395,590) are used to investigate the near wall scaling of various turbulence quantities. We find that as the Reynolds number increases, the extent of the region where the production of the kinetic energy is equal to the dissipation increases. At the highest Reynolds number the region of equilibrium extends from y+ - 120 to y+ = 240. As the Reynolds number increases, we find that wall scaling collapses the budgets for the streamwise fluctuating component, but the budgets for the other two components show Reynolds number dependency.

  1. Attentional bias for caffeine-related stimuli in high but not moderate or non-caffeine consumers.

    Science.gov (United States)

    Yeomans, Martin R; Javaherian, Shabnam; Tovey, Heather M; Stafford, Lorenzo D

    2005-09-01

    Attentional bias for drug-related cues has been reported with a wide range of drugs, but to date the extent to which caffeine consumers show similar biases for caffeine-related stimuli has not been tested. The present study therefore examined this issue in terms of differences in attentional bias for caffeine-related words in High, Moderate and Non-caffeine consumers using a dot-probe word task following overnight caffeine abstinence. This study was conducted to test whether caffeine consumers show an attentional bias for caffeine-related words, and whether such biases relate to habitual levels of caffeine use. Sixteen High, Moderate and Non-consumers of caffeine were asked to complete a modified dot-probe task in order to measure attentional bias for caffeine-related relative to neutral control word groups. The task was completed following overnight caffeine abstinence, and participants also completed mood and caffeine-craving measures. The High consumer group showed a significant attentional bias for the caffeine-related words, but no such bias was seen in Moderate or Non-consumer groups. As expected, craving for caffeine was strongest in the High consumers and weakest in the Non-consumers. Attentional bias in the High group correlated with self-reported caffeine consumption and with craving for caffeine, but neither effect was significant in the Moderate group. These data confirm that High caffeine consumers show attentional bias for caffeine-related stimuli, consistent with current theories of drug addiction.

  2. Moderate carbohydrate, moderate protein weight loss diet reduces cardiovascular disease risk compared to high carbohydrate, low protein diet in obese adults: A randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Evans Ellen M

    2008-11-01

    Full Text Available Abstract Background To evaluate the metabolic effects of two weight loss diets differing in macronutrient composition on features of dyslipidemia and post-prandial insulin (INS response to a meal challenge in overweight/obese individuals. Methods This study was a parallel-arm randomized 4 mo weight loss trial. Adults (n = 50, 47 ± 7 y matched on BMI (33.6 ± 0.6 kg/m2, P = 0.79 consumed energy restricted diets (deficit ~500 kcal/d: PRO (1.6 g.kg-1.d-1 protein and -1.d-1 protein and > 220 g/d carbohydrate for 4 mos. Meal challenges of respective diets were utilized for determination of blood lipids and post-prandial INS and glucose response at the beginning and end of the study. Results There was a trend for PRO to lose more weight (-9.1% vs. -7.3%, P = 0.07 with a significant reduction in percent fat mass compared to CHO (-8.7% vs. -5.7%; P = 0.03. PRO also favored reductions in triacylglycerol (-34% vs. -14%; P P = 0.05; however, CHO favored reduction in LDL-C (-7% vs. +2.5%; P P P Conclusion A weight loss diet with moderate carbohydrate, moderate protein results in more favorable changes in body composition, dyslipidemia, and post-prandial INS response compared to a high carbohydrate, low protein diet suggesting an additional benefit beyond weight management to include augmented risk reduction for metabolic disease.

  3. Effects of high nitrogen concentrations on the growth of submersed macrophytes at moderate phosphorus concentrations.

    Science.gov (United States)

    Yu, Qing; Wang, Hong-Zhu; Li, Yan; Shao, Jian-Chun; Liang, Xiao-Min; Jeppesen, Erik; Wang, Hai-Jun

    2015-10-15

    Eutrophication of lakes leading to loss of submersed macrophytes and higher turbidity is a worldwide phenomenon, attributed to excessive loading of phosphorus (P). However, recently, the role of nitrogen (N) for macrophyte recession has received increasing attention. Due to the close relationship between N and P loading, disentanglement of the specific effects of these two nutrients is often difficult, and some controversy still exists as to the effects of N. We studied the effects of N on submersed macrophytes represented by Vallisneria natans (Lour.) Hara in pots positioned at three depths (0.4 m, 0.8 m, and 1.2 m to form a gradient of underwater light conditions) in 10 large ponds having moderate concentrations of P (TP 0.03 ± 0.04 mg L(-1)) and five targeted concentrations of total nitrogen (TN) (0.5, 2, 10, 20, and 100 mg L(-1)), there were two ponds for each treatment. To study the potential shading effects of other primary producers, we also measured the biomass of phytoplankton (ChlaPhyt) and periphyton (ChlaPeri) expressed as chlorophyll a. We found that leaf length, leaf mass, and root length of macrophytes declined with increasing concentrations of TN and ammonium, while shoot number and root mass did not. All the measured growth indices of macrophytes declined significantly with ChlaPhyt, while none were significantly related to ChlaPeri. Neither ChlaPhyt nor ChlaPeri were, however, significantly negatively related to the various N concentrations. Our results indicate that shading by phytoplankton unrelated to the variation in N loading and perhaps toxic stress exerted by high nitrogen were responsible for the decline in macrophyte growth. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. High-Intensity Interval Training Elicits Higher Enjoyment than Moderate Intensity Continuous Exercise

    Science.gov (United States)

    Thum, Jacob S.; Parsons, Gregory; Whittle, Taylor

    2017-01-01

    Exercise adherence is affected by factors including perceptions of enjoyment, time availability, and intrinsic motivation. Approximately 50% of individuals withdraw from an exercise program within the first 6 mo of initiation, citing lack of time as a main influence. Time efficient exercise such as high intensity interval training (HIIT) may provide an alternative to moderate intensity continuous exercise (MICT) to elicit substantial health benefits. This study examined differences in enjoyment, affect, and perceived exertion between MICT and HIIT. Twelve recreationally active men and women (age = 29.5 ± 10.7 yr, VO2max = 41.4 ± 4.1 mL/kg/min, BMI = 23.1 ± 2.1 kg/m2) initially performed a VO2max test on a cycle ergometer to determine appropriate workloads for subsequent exercise bouts. Each subject returned for two additional exercise trials, performing either HIIT (eight 1 min bouts of cycling at 85% maximal workload (Wmax) with 1 min of active recovery between bouts) or MICT (20 min of cycling at 45% Wmax) in randomized order. During exercise, rating of perceived exertion (RPE), affect, and blood lactate concentration (BLa) were measured. Additionally, the Physical Activity Enjoyment Scale (PACES) was completed after exercise. Results showed higher enjoyment (p = 0.013) in response to HIIT (103.8 ± 9.4) versus MICT (84.2 ± 19.1). Eleven of 12 participants (92%) preferred HIIT to MICT. However, affect was lower (pHIIT versus MICT. Although HIIT is more physically demanding than MICT, individuals report greater enjoyment due to its time efficiency and constantly changing stimulus. Trial Registration: NCT:02981667. PMID:28076352

  5. High-Intensity Interval Training Elicits Higher Enjoyment than Moderate Intensity Continuous Exercise.

    Directory of Open Access Journals (Sweden)

    Jacob S Thum

    Full Text Available Exercise adherence is affected by factors including perceptions of enjoyment, time availability, and intrinsic motivation. Approximately 50% of individuals withdraw from an exercise program within the first 6 mo of initiation, citing lack of time as a main influence. Time efficient exercise such as high intensity interval training (HIIT may provide an alternative to moderate intensity continuous exercise (MICT to elicit substantial health benefits. This study examined differences in enjoyment, affect, and perceived exertion between MICT and HIIT. Twelve recreationally active men and women (age = 29.5 ± 10.7 yr, VO2max = 41.4 ± 4.1 mL/kg/min, BMI = 23.1 ± 2.1 kg/m2 initially performed a VO2max test on a cycle ergometer to determine appropriate workloads for subsequent exercise bouts. Each subject returned for two additional exercise trials, performing either HIIT (eight 1 min bouts of cycling at 85% maximal workload (Wmax with 1 min of active recovery between bouts or MICT (20 min of cycling at 45% Wmax in randomized order. During exercise, rating of perceived exertion (RPE, affect, and blood lactate concentration (BLa were measured. Additionally, the Physical Activity Enjoyment Scale (PACES was completed after exercise. Results showed higher enjoyment (p = 0.013 in response to HIIT (103.8 ± 9.4 versus MICT (84.2 ± 19.1. Eleven of 12 participants (92% preferred HIIT to MICT. However, affect was lower (p<0.05 and HR, RPE, and BLa were higher (p<0.05 in HIIT versus MICT. Although HIIT is more physically demanding than MICT, individuals report greater enjoyment due to its time efficiency and constantly changing stimulus.NCT:02981667.

  6. Moderate sensitivity and high specificity of emergency department administrative data for transient ischemic attacks.

    Science.gov (United States)

    Yu, Amy Y X; Quan, Hude; McRae, Andrew; Wagner, Gabrielle O; Hill, Michael D; Coutts, Shelagh B

    2017-09-18

    Validation of administrative data case definitions is key for accurate passive surveillance of disease. Transient ischemic attack (TIA) is a condition primarily managed in the emergency department. However, prior validation studies have focused on data after inpatient hospitalization. We aimed to determine the validity of the Canadian 10th International Classification of Diseases (ICD-10-CA) codes for TIA in the national ambulatory administrative database. We performed a diagnostic accuracy study of four ICD-10-CA case definition algorithms for TIA in the emergency department setting. The study population was obtained from two ongoing studies on the diagnosis of TIA and minor stroke versus stroke mimic using serum biomarkers and neuroimaging. Two reference standards were used 1) the emergency department clinical diagnosis determined by chart abstractors and 2) the 90-day final diagnosis, both obtained by stroke neurologists, to calculate the sensitivity, specificity, positive and negative predictive values (PPV and NPV) of the ICD-10-CA algorithms for TIA. Among 417 patients, emergency department adjudication showed 163 (39.1%) TIA, 155 (37.2%) ischemic strokes, and 99 (23.7%) stroke mimics. The most restrictive algorithm, defined as a TIA code in the main position had the lowest sensitivity (36.8%), but highest specificity (92.5%) and PPV (76.0%). The most inclusive algorithm, defined as a TIA code in any position with and without query prefix had the highest sensitivity (63.8%), but lowest specificity (81.5%) and PPV (68.9%). Sensitivity, specificity, PPV, and NPV were overall lower when using the 90-day diagnosis as reference standard. Emergency department administrative data reflect diagnosis of suspected TIA with high specificity, but underestimate the burden of disease. Future studies are necessary to understand the reasons for the low to moderate sensitivity.

  7. The influence of the Reynolds number on the passive scalar field in a turbulent channel flow

    International Nuclear Information System (INIS)

    Bergant, R.; Tiselj, I.

    2006-01-01

    Many different turbulent heat transfer calculations based on a very accurate pseudo-spectral code have been performed in the last 5 years. The main effort was to investigate temperature fields at different Prandtl numbers, ranging from Pr=0.7 to Pr=200. For the treatment of the turbulent heat transfer at low Reynolds and high Prandtl numbers, a Direct Numerical Simulation (DNS) was used for structures of the turbulent motions. DNS describes all the length and time scales for velocity and temperature fields. When Prandtl number is higher than 1, the smallest temperature scales are approximately inversely proportional to the square root of Prandtl number. For the smallest temperature scales, not resolved in the high Prandtl number simulation, a spectral turbulent diffusivity model was used in the pseudo-spectral computer code for DNS. A comparison of our temperature profiles obtained at friction Reynolds number Reτ=150 and Pr=100 and Pr=200 to the mean profiles of Calmet and Magnaudet, Wang and Lu and Kader's correlation that was built as a best fit of various experimental data at higher Reynolds numbers, revealed the discrepancies up to 10%. The most important reason for the differences was in different Reynolds numbers, which were much lower in our simulations than in the above mentioned LES simulations and experiments. The similar phenomenon as in our case can be found when DNS of Kawamura and Kader's results at Reτ=180 and Pr=0.71 were compared. On the other hand, the comparisons to the Kader's correlation at higher Reynolds numbers (i.e. DNS of Kawamura at Reτ=640 and DNS of Tiselj at Reτ=424) show that the differences are within statistical uncertainties. It follows that the heat transfer depends much more on Reynolds number in the range of low Reynolds numbers than in the range of high Reynolds numbers. (author)

  8. The Penguin: a Low Reynolds Number Powered Glider for Station Keeping Missions

    Science.gov (United States)

    Costello, J. K.; Greene, D. W.; Lee, T. T.; Matier, P. T.; Mccarthy, T. R.; Mcguire, R. J.; Schuette, M. J.

    1990-01-01

    The Penguin is a low Reynolds number (approx. 100,000) remotely piloted vehicle (RPV). It was designed to fly three laps indoors around two pylons in a figure-eight course while maximizing loiter time. The Penguin's low Reynolds number mission is an important one currently being studied for possible future flights in the atmospheres of other planets and for specialized military missions. Although the Penguin's mission seemed quite simple at first, the challenges of such low Reynolds number flight have proven to be quite unique. In addition to the constraint of low Reynolds number flight, the aircraft had to be robust in its control, highly durable, and it had to carry a small instrument package. The Penguin's flight plan, concept, performance, aerodynamic design, weight estimation, structural design, propulsion, stability and control, and cost estimate is detailed.

  9. Evaluation of the acute adverse reaction of contrast medium with high and moderate iodine concentration in patients undergoing computed tomography

    International Nuclear Information System (INIS)

    Nagamoto, Masashi; Gomi, Tatsuya; Terada, Hitoshi; Terada, Shigehiko; Kohda, Eiichi

    2006-01-01

    The aim of this prospective study was to evaluate and compare acute adverse reactions between contrast medium containing moderate and high concentrations of iodine in patients undergoing computed tomography (CT). A total of 945 patients undergoing enhanced CT were randomly assigned to receive one of two doses of contrast medium. We then prospectively investigated the incidence of adverse reactions. Iopamidol was used as the contrast medium, with a high concentration of 370 mgI/ml and a moderate concentration of 300 mgI/ml. The frequency of adverse reactions, such as pain at the injection site and heat sensation, were determined. Acute adverse reactions were observed in 2.4% (11/458) of the moderate-concentration group compared to 3.11% (15/482) of the high-concentration group; there was no significant difference in incidence between the two groups. Most adverse reactions were mild, and there was no significant difference in severity. One patient in the high-concentration group was seen to have a moderate adverse reaction. No correlation existed between the incidence of adverse reactions and patient characteristics such as sex, age, weight, flow amount, and flow rate. The incidence of pain was not significantly different between the two groups. In contrast, the incidence of heat sensation was significantly higher in the high-concentration group. The incidence and severity of acute adverse reactions were not significantly different between the two groups, and there were no severe adverse reactions in either group. (author)

  10. JENDL-3.2 performance in analyses of MISTRAL critical experiments for high-moderation MOX cores

    International Nuclear Information System (INIS)

    Takada, Naoyuki; Hibi, Koki; Ishii, Kazuya; Ando, Yoshihira; Yamamoto, Toru; Ueji, Masao; Iwata, Yutaka

    2001-01-01

    NUPEC and CEA have launched an extensive experimental program called MISTRAL to study highly moderated MOX cores for the advanced LWRs. The analyses using SRAC system and MVP code with JENDL-3.2 library are in progress on the experiments of the MISTRAL and the former EPICURE programs. Various comparisons have been made between calculation results and measurement values. (author)

  11. The Effects of Moderate- and High-Fidelity Patient Simulator Use on Critical Thinking in Associate Degree Nursing Students

    Science.gov (United States)

    Vieck, Jana

    2013-01-01

    The purpose of this study was to examine the impact of moderate- and high-fidelity patient simulator use on the critical thinking skills of associate degree nursing students. This quantitative study used a quasi-experimental design and the Health Sciences Reasoning Test (HSRT) to evaluate the critical thinking skills of third semester nursing…

  12. Do Barriers to Crime Prevention Moderate the Effects of Situational Crime Prevention Policies on Violent Crime in High Schools?

    Science.gov (United States)

    Sevigny, Eric L.; Zhang, Gary

    2018-01-01

    This study investigates how barriers to school-based crime prevention programming moderate the effects of situational crime prevention (SCP) policies on levels of violent crime in U.S. public high schools. Using data from the 2008 School Survey on Crime and Safety, we estimate a series of negative binomial regression models with interactions to…

  13. Moderate alcohol consumption aggravates high fat-diet induced steatohepatitis in rats

    Science.gov (United States)

    Background: Nonalcoholic steatohepatitis (NASH) develops in the absence of chronic and excessive alcohol consumption. However, it remains unknown whether moderate alcohol consumption aggravates liver inflammation in pre-existing NASH condition. Methods: Sprague-Dawley rats were first fed ad libitum...

  14. Atomic collision studies at moderate projectile velocities using highly charged, decelerated heavy ions from the GSI-UNILAC

    International Nuclear Information System (INIS)

    Mokler, P.H.; Hoffmann, D.H.H.; Schoenfeldt, W.A.; Maor, D.

    1984-01-01

    Beams of highly ionized, very heavy atoms at moderate velocities have been produced at the UNILAC using the acceleration-stripping-deceleration method. The available ion species range from Kr 33+ to U 66+ in the energy region between 2 and 5 MeV/u. A survey on first experiments at GSI using these moderate velocity, few electron, heavy ion beams is given. The effectiveness of the method is demonstrated for Xesup(q+)-Xe collision experiments with 41 <= q <= 45. Results on vacancy transfer between inner quasimolecular levels for close collisions, and on distant collision electron capture are reported. (orig.)

  15. Revolutionary Performance For Ultra Low Reynolds Number Vehicles, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — A novel technique for controlling transition from laminar to turbulent flow in very low Reynolds number conditions has been developed. Normally flows with Reynolds...

  16. Behaviour of neutron moderator materials at high temperatures in CASTOR registered -casks: qualification and assessment

    International Nuclear Information System (INIS)

    Krietsch, T.; Wolff, D.; Knopp, U.; Brocke, H.D.

    2004-01-01

    The Federal Institute for Materials Research and Testing (BAM) is the responsible German authority for the assessment of mechanical and thermal designs of transport and storage casks for radioactive materials. BAM checks up the proofs of the applicants in their safety reports and assesses the conformity to the Regulations for the Safe Transport of Radioactive Material. One applicant is the Gesellschaft fuer Nuklear-Behaelter mbH (GNB) with a new generation of transport and storage casks of CASTOR registered -design. GNB typically uses ultra high molecular weight Polyethylene (UHMW-PE) for the moderation of free neutrons. Rods made of UHMW-PE are positioned in axial bore holes in the wall of the cask and plates of UHMW-PE are in free spaces between primary and secondary lid and between the bottom of the cask and an outer plate (Figure 1). Because of the heat generated by the radioactive inventory and because of a strained spring at the bottom of every bore hole, UHMW-PE is subjected to permanent thermal and mechanical loads as well as loads from gamma and neutron radiation. UHMW-PE has been used under routine- and normal conditions of transport for maximum temperatures up to 130 C. For new generations of CASTOR registered -design maximum temperatures will be increased up to 160 C. That means a permanent use of UHMW-PE at temperatures within and above the melting region of the crystallites. In this paper, some results of special investigations for the proofs of usability of UHMW-PE at temperatures up to 160 C under real conditions of transport and storage in CASTOR registered -casks are given. For that, investigations on temperature dependent expansion behaviour under laboratory conditions as well as in large scale experiments, especially in the case of multiple heating and cooling, were done. Besides, geometrical creep strength for long-term loading by temperatures and pressures with regard to the chemical and physical stability properties of UHMW-PE above the

  17. Changes in higher order aberrations after wavefront guided FS-LASIK for myopia combined with moderate to high astigmatism

    Directory of Open Access Journals (Sweden)

    Cang-Yu Guan

    2018-02-01

    Full Text Available AIM: To assess the changes in higher order aberrations after wavefront guided femtosecond laser assisted laser in situ keratomileusis(FS-LASIKfor moderate to high astigmatism. METHODS: Eighty-eight eyes of 50 myopia patients with moderate to high astigmatism were included in this prospective study. There were 51 eyes with moderate astigmatism(≥-1.50D and RESULTS: At the 3mo after operation, the mean UDVA of all eyes was above 20/20, better than before operation(PP=0.36and no eyes lost ≥2 lines of CDVA. Mean astigmstism of 85 eyes(97%was reduced below -1.00D, mean astigmatism of 70 eyes(80%was reduced below -0.50D(PPP=0.078, 0.065. The spherical aberration, secondary astigmatism and the HOA root mean square(RMSincreased from 0.19±0.06, 0.05±0.02 and 0.42±0.12, preoperatively to 0.32±0.17, 0.26±0.08 and 0.78±0.28(PCONCLUSION: Wavefront-guided FS-LASIK is a safe and effective option for the patients with moderate to high astigmstism although parts of HOAs increased.

  18. Is Moderate Intensity Exercise Training Combined with High Intensity Interval Training More Effective at Improving Cardiorespiratory Fitness than Moderate Intensity Exercise Training Alone?

    Directory of Open Access Journals (Sweden)

    Brendon H. Roxburgh, Paul B. Nolan, Ryan M. Weatherwax, Lance C. Dalleck

    2014-09-01

    Full Text Available The purpose of this study was to compare the effectiveness of either continuous moderate intensity exercise training (CMIET alone vs. CMIET combined with a single weekly bout of high intensity interval training (HIIT on cardiorespiratory fitness. Twenty nine sedentary participants (36.3 ± 6.9 yrs at moderate risk of cardiovascular disease were recruited for 12 weeks of exercise training on a treadmill and cycle ergometer. Participants were randomised into three groups: CMIET + HIIT (n = 7; 8-12 x 60 sec at 100% VO2max, 150 sec active recovery, CMIET (n = 6; 30 min at 45-60% oxygen consumption reserve (VO2R and a sedentary control group (n = 7. Participants in the CMIET + HIIT group performed a single weekly bout of HIIT and four weekly sessions of CMIET, whilst the CMIET group performed five weekly CMIET sessions. Probabilistic magnitude-based inferences were determined to assess the likelihood that the true value of the effect represents substantial change. Relative VO2max increased by 10.1% (benefit possible relative to control in in the CMIET + HIIT group (32.7 ± 9.2 to 36.0 ± 11.5 mL·kg-1·min-1 and 3.9% (benefit possible relative to control in the CMIET group (33.2 ± 4.0 to 34.5 ± 6.1 mL·kg-1·min-1, whilst there was a 5.7% decrease in the control group (30.0 ± 4.6 to 28.3 ± 6.5 mL·kg-1·min-1. It was ‘unclear’ if a clinically significant difference existed between the effect of CMIET + HIIT and CMIET on the change in VO2max. Both exercising groups showed clinically meaningful improvements in VO2max. Nevertheless, it remains ‘unclear’ whether one type of exercise training regimen elicits a superior improvement in cardiorespiratory fitness relative to its counterpart.

  19. Effects of relative thickness on aerodynamic characteristics of airfoil at a low Reynolds number

    Directory of Open Access Journals (Sweden)

    Ma Dongli

    2015-08-01

    Full Text Available This study focuses on the characteristics of low Reynolds number flow around airfoil of high-altitude unmanned aerial vehicles (HAUAVs cruising at low speed. Numerical simulation on the flows around several representative airfoils is carried out to investigate the low Reynolds number flow. The water tunnel model tests further validate the accuracy and effectiveness of the numerical method. Then the effects of the relative thickness of airfoil on aerodynamic performance are explored, using the above numerical method, by simulating flows around airfoils of different relative thicknesses (12%, 14%, 16%, 18%, as well as different locations of the maximum relative thickness (x/c = 22%, 26%, 30%, 34%, at a low Reynolds number of 5 × 105. Results show that performance of airfoils at low Reynolds number is mainly affected by the laminar separation bubble. On the premise of good stall characteristics, the value of maximum relative thickness should be as small as possible, and the location of the maximum relative thickness ought to be closer to the trailing edge to obtain fine airfoil performance. The numerical method is feasible for the simulation of low Reynolds number flow. The study can help to provide a basis for the design of low Reynolds number airfoil.

  20. 77 FR 37316 - Drawbridge Operation Regulations; Reynolds Channel, Nassau, NY

    Science.gov (United States)

    2012-06-21

    ... Regulations; Reynolds Channel, Nassau, NY AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation from... regulations governing the operation of the Long Beach Bridge, mile 4.7, across Reynolds Channel, at Nassau...: The Long Beach Bridge, across Reynolds Channel, mile 4.7, at Nassau, New York, has a vertical...

  1. 78 FR 26508 - Drawbridge Operation Regulations; Reynolds Channel, Nassau, NY

    Science.gov (United States)

    2013-05-07

    ... Regulations; Reynolds Channel, Nassau, NY AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation from... regulation governing the operation of the Long Beach Bridge, mile 4.7, across Reynolds Channel at Nassau, New.... on July 12, 2013. Reynolds Creek has commercial and recreational vessel traffic. No objections were...

  2. 78 FR 66265 - Drawbridge Operation Regulations; Reynolds Channel, Lawrence, NY

    Science.gov (United States)

    2013-11-05

    ... Regulations; Reynolds Channel, Lawrence, NY AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation... from the regulations governing the operation of the Atlantic Beach Bridge, mile 0.4, across Reynolds.... SUPPLEMENTARY INFORMATION: The Atlantic Beach Bridge, across Reynolds Channel, mile 0.4, at Lawrence, New York...

  3. 78 FR 56609 - Drawbridge Operation Regulations; Reynolds Channel, Lawrence, NY

    Science.gov (United States)

    2013-09-13

    ... Regulations; Reynolds Channel, Lawrence, NY AGENCY: Coast Guard, DHS. ACTION: Notice canceling temporary... Beach Bridge, mile 0.4, across Reynolds Channel, at Lawrence, New York. The owner of the bridge, Nassau... published a temporary deviation entitled ``Drawbridge Operation Regulations; Reynolds Channel, Lawrence, NY...

  4. 78 FR 37456 - Drawbridge Operation Regulations; Reynolds Channel, Nassau, NY

    Science.gov (United States)

    2013-06-21

    ... Regulations; Reynolds Channel, Nassau, NY AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation from... regulation governing the operation of the Long Beach Bridge, mile 4.7, across Reynolds Channel at Nassau, New... July 1, 2013. Reynolds Creek has commercial and recreational vessel traffic. No objections were...

  5. 78 FR 34893 - Drawbridge Operation Regulations; Reynolds Channel, Lawrence, NY

    Science.gov (United States)

    2013-06-11

    ... Regulations; Reynolds Channel, Lawrence, NY AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation... from the regulations governing the operation of the Atlantic Beach Bridge, mile 0.4, across Reynolds... Reynolds Channel, mile 0.4, at Lawrence, New York, has a vertical clearance in the closed position of 25...

  6. 78 FR 56610 - Drawbridge Operation Regulations; Reynolds Channel, Lawrence, NY

    Science.gov (United States)

    2013-09-13

    ... Regulations; Reynolds Channel, Lawrence, NY AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation... from the regulations governing the operation of the Atlantic Beach Bridge, mile 0.4, across Reynolds.... SUPPLEMENTARY INFORMATION: The Atlantic Beach Bridge, across Reynolds Channel, mile 0.4, at Lawrence, New York...

  7. Reynolds stress of localized toroidal modes

    International Nuclear Information System (INIS)

    Zhang, Y.Z.; Mahajan, S.M.

    1995-02-01

    An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant

  8. Reynolds stress of localized toroidal modes

    International Nuclear Information System (INIS)

    Zhang, Y.Z.; Mahajan, S.M.

    1995-01-01

    An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at π/2 (or -π/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant. (author). 15 refs

  9. THE EFFECT OF MODERATE AND HIGH-INTENSITY FATIGUE ON GROUNDSTROKE ACCURACY IN EXPERT AND NON-EXPERT TENNIS PLAYERS

    Directory of Open Access Journals (Sweden)

    Mark Lyons

    2013-06-01

    Full Text Available Exploring the effects of fatigue on skilled performance in tennis presents a significant challenge to the researcher with respect to ecological validity. This study examined the effects of moderate and high-intensity fatigue on groundstroke accuracy in expert and non-expert tennis players. The research also explored whether the effects of fatigue are the same regardless of gender and player's achievement motivation characteristics. 13 expert (7 male, 6 female and 17 non-expert (13 male, 4 female tennis players participated in the study. Groundstroke accuracy was assessed using the modified Loughborough Tennis Skills Test. Fatigue was induced using the Loughborough Intermittent Tennis Test with moderate (70% and high-intensities (90% set as a percentage of peak heart rate (attained during a tennis-specific maximal hitting sprint test. Ratings of perceived exertion were used as an adjunct to the monitoring of heart rate. Achievement goal indicators for each player were assessed using the 2 x 2 Achievement Goals Questionnaire for Sport in an effort to examine if this personality characteristic provides insight into how players perform under moderate and high-intensity fatigue conditions. A series of mixed ANOVA's revealed significant fatigue effects on groundstroke accuracy regardless of expertise. The expert players however, maintained better groundstroke accuracy across all conditions compared to the novice players. Nevertheless, in both groups, performance following high-intensity fatigue deteriorated compared to performance at rest and performance while moderately fatigued. Groundstroke accuracy under moderate levels of fatigue was equivalent to that at rest. Fatigue effects were also similar regardless of gender. No fatigue by expertise, or fatigue by gender interactions were found. Fatigue effects were also equivalent regardless of player's achievement goal indicators. Future research is required to explore the effects of fatigue on

  10. The Impact of Low, Moderate, and High Military Family Mobility School District Transfer Rates on Graduating Senior High School Dependents' Achievement and School Engagement

    Science.gov (United States)

    Rippe, Jeffrey K.

    2012-01-01

    The results of this study suggest that there were no significant differences in the academic performance of military dependents' with low (n = 20), moderate (n = 20), and high (n = 20) mobility school district transfer rates compared to non-military control students (n = 20) before completing high school. The findings were not consistent with…

  11. THE IMPACT OF MODERATE AND HIGH INTENSITY TOTAL BODY FATIGUE ON PASSING ACCURACY IN EXPERT AND NOVICE BASKETBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Mark Lyons

    2006-06-01

    Full Text Available Despite the acknowledged importance of fatigue on performance in sport, ecologically sound studies investigating fatigue and its effects on sport-specific skills are surprisingly rare. The aim of this study was to investigate the effect of moderate and high intensity total body fatigue on passing accuracy in expert and novice basketball players. Ten novice basketball players (age: 23.30 ± 1.05 yrs and ten expert basketball players (age: 22.50 ± 0.41 yrs volunteered to participate in the study. Both groups performed the modified AAHPERD Basketball Passing Test under three different testing conditions: rest, moderate intensity and high intensity total body fatigue. Fatigue intensity was established using a percentage of the maximal number of squat thrusts performed by the participant in one minute. ANOVA with repeated measures revealed a significant (F 2,36 = 5.252, p = 0.01 level of fatigue by level of skill interaction. On examination of the mean scores it is clear that following high intensity total body fatigue there is a significant detriment in the passing performance of both novice and expert basketball players when compared to their resting scores. Fundamentally however, the detrimental impact of fatigue on passing performance is not as steep in the expert players compared to the novice players. The results suggest that expert or skilled players are better able to cope with both moderate and high intensity fatigue conditions and maintain a higher level of performance when compared to novice players. The findings of this research therefore, suggest the need for trainers and conditioning coaches in basketball to include moderate, but particularly high intensity exercise into their skills sessions. This specific training may enable players at all levels of the game to better cope with the demands of the game on court and maintain a higher standard of play

  12. Effects of moderate-dose versus high-dose trimethoprim on serum creatinine and creatinine clearance and adverse reactions.

    OpenAIRE

    Naderer, O; Nafziger, A N; Bertino, J S

    1997-01-01

    The effects of a 10-day course of moderate-dose (10 mg/kg/day) or high-dose (20 mg/kg/day) trimethoprim therapy on serum creatinine, measured creatinine clearance, urinary creatinine excretion, and serum folate were studied in 20 healthy volunteers. Serum creatinine concentrations increased significantly during trimethoprim therapy, began to decrease near day 10, and returned to baseline during the washout phase at both dosage levels. At the same time, measured creatinine clearance and urine ...

  13. High-intensity interval training vs. moderate-intensity continuous training in the prevention/management of cardiovascular disease

    OpenAIRE

    Hussain, S; Macaluso, A; Pearson, S

    2016-01-01

    Moderate-intensity continuous training (MICT) has long been considered the most effective exercise treatment modality for the prevention and management of cardiovascular disease, but more recently high-intensity interval training (HIIT) has emerged into the clinical environment has been viewed as a potential alternative to MICT in accruing such benefits. HIIT was initially found to induce significant improvements in numerous physiological and health-related indices, to a similar if not superi...

  14. Local vibrations and lift performance of low Reynolds number airfoil

    Directory of Open Access Journals (Sweden)

    TariqAmin Khan

    2017-06-01

    Full Text Available The 2D incompressible Navier-Stokes equations are solved based on the finite volume method and dynamic mesh technique is used to carry out partial fluid structure interaction. The local flexible structure (hereinafter termed as flexible structure vibrates in a single mode located on the upper surface of the airfoil. The Influence of vibration frequency and amplitude are examined and the corresponding fluid flow characteristics are investigated which add complexity to the inherent problem in unsteady flow. The study is conducted for flow over NACA0012 airfoil at 600≤Re≤3000 at a low angle of attack. Vibration of flexible structure induces a secondary vortex which modifies the pressure distribution and lift performance of the airfoil. At some moderate vibration amplitude, frequency synchronization or lock-in phenomenon occurs when the vibration frequency is close to the characteristic frequency of rigid airfoil. Evolution and shedding of vortices corresponding to the deformation of flexible structure depends on the Reynolds number. In the case of Re≤1000, the deformation of flexible structure is considered in-phase with the vortex shedding i.e., increasing maximum lift is linked with the positive deformation of flexible structure. At Re=1500 a phase shift of about 1/π exists while they are out-of-phase at Re>1500. Moreover, the oscillation amplitude of lift coefficient increases with increasing vibration amplitude for Re≤1500 while it decreases with increasing vibration amplitude for Re>1500. As a result of frequency lock-in, the average lift coefficient is increased with increasing vibration amplitude for all investigated Reynolds numbers (Re. The maximum increase in the average lift coefficient is 19.72% within the range of investigated parameters.

  15. Effects of caffeine on neuromuscular fatigue and performance during high-intensity cycling exercise in moderate hypoxia.

    Science.gov (United States)

    Smirmaul, Bruno P C; de Moraes, Antonio Carlos; Angius, Luca; Marcora, Samuele M

    2017-01-01

    To investigate the effects of caffeine on performance, neuromuscular fatigue and perception of effort during high-intensity cycling exercise in moderate hypoxia. Seven adult male participants firstly underwent an incremental exercise test on a cycle ergometer in conditions of acute normobaric hypoxia (fraction inspired oxygen = 0.15) to establish peak power output (PPO). In the following two visits, they performed a time to exhaustion test (78 ± 3% PPO) in the same hypoxic conditions after caffeine ingestion (4 mg kg -1 ) and one after placebo ingestion in a double-blind, randomized, counterbalanced cross-over design. Caffeine significantly improved time to exhaustion by 12%. A significant decrease in subjective fatigue was found after caffeine consumption. Perception of effort and surface electromyographic signal amplitude of the vastus lateralis were lower and heart rate was higher in the caffeine condition when compared to placebo. However, caffeine did not reduce the peripheral and central fatigue induced by high-intensity cycling exercise in moderate hypoxia. The caffeine-induced improvement in time to exhaustion during high-intensity cycling exercise in moderate hypoxia seems to be mediated by a reduction in perception of effort, which occurs despite no reduction in neuromuscular fatigue.

  16. A comparison of three approaches to compute the effective Reynolds number of the implicit large-eddy simulations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ye [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thornber, Ben [The Univ. of Sydney, Sydney, NSW (Australia)

    2016-04-12

    Here, the implicit large-eddy simulation (ILES) has been utilized as an effective approach for calculating many complex flows at high Reynolds number flows. Richtmyer–Meshkov instability (RMI) induced flow can be viewed as a homogeneous decaying turbulence (HDT) after the passage of the shock. In this article, a critical evaluation of three methods for estimating the effective Reynolds number and the effective kinematic viscosity is undertaken utilizing high-resolution ILES data. Effective Reynolds numbers based on the vorticity and dissipation rate, or the integral and inner-viscous length scales, are found to be the most self-consistent when compared to the expected phenomenology and wind tunnel experiments.

  17. Moderate Contrast in the Evaluation of Paintings Is Liked More but Remembered Less than High Contrast

    Directory of Open Access Journals (Sweden)

    Katinka Dijkstra

    2017-09-01

    Full Text Available Many visual aspects of paintings, as well as exposure to art and cultural norms, contribute to the aesthetic evaluation of paintings. The current study looked at heightened visual contrast as an important factor in the appreciation of paintings. Participants evaluated abstract digitized paintings that were manipulated in contrast for an appreciation task and were later presented with these paintings in a memory task. The results indicated that for art appreciation, a moderate increase in contrast resulted in the highest appreciation for paintings whereas recognition memory was better for paintings with a higher increase in contrast. These results replicate earlier findings with regard to the role of contrast in aesthetic perception and extend these findings by demonstrating a surprising different effect of contrast manipulation for recognition memory. Confidence with which memory decisions were made was in line with art appreciation decisions not memory performance.

  18. The thermal structure of a wind-driven Reynolds ridge

    Energy Technology Data Exchange (ETDEWEB)

    Phongikaroon, Supathorn; Peter Judd, K.; Smith, Geoffrey B.; Handler, Robert A. [Remote Sensing Division, Naval Research Laboratory, 20375, Washington, DC (United States)

    2004-08-01

    In this study, we investigate the nature of a Reynolds ridge formed by wind shear. We have simultaneously imaged the water surface, with a deposit of a monolayer of the surfactant, oleyl alcohol, subject to different wind shears, by using a high-resolution infrared (IR) detector and a high-speed (HS) digital camera. The results reveal that the regions around the wind-driven Reynolds ridge, which have subtle manifestations in visual imagery, possess surprisingly complex hydrodynamical and thermal structures when observed in the infrared. The IR measurements reveal a warm, clean region upstream of the ridge, which is composed of the so called fishscale structures observed in earlier investigations. The region downstream of the ridge is composed of colder fluid which forms two counter-rotating cells. A region of intermediate temperature, which we call the mixing (wake) region, forms immediately downstream of the ridge near the channel centerline. By measuring the velocity of the advected fishscales, we have determined a surface drift speed of about 2% of the wind speed. The spanwise length-scale of the structures has also been used to estimate the wind shear. In addition, a comparison of IR and visual imagery shows that the thermal field is a very sensitive indicator of the exact position of the ridge itself. (orig.)

  19. Hybrid Reynolds-Averaged/Large Eddy Simulation of the Flow in a Model SCRamjet Cavity Flameholder

    Science.gov (United States)

    Baurle, R. A.

    2016-01-01

    Steady-state and scale-resolving simulations have been performed for flow in and around a model scramjet combustor flameholder. Experimental data available for this configuration include velocity statistics obtained from particle image velocimetry. Several turbulence models were used for the steady-state Reynolds-averaged simulations which included both linear and non-linear eddy viscosity models. The scale-resolving simulations used a hybrid Reynolds-averaged/large eddy simulation strategy that is designed to be a large eddy simulation everywhere except in the inner portion (log layer and below) of the boundary layer. Hence, this formulation can be regarded as a wall-modeled large eddy simulation. This e ort was undertaken to not only assess the performance of the hybrid Reynolds-averaged / large eddy simulation modeling approach in a flowfield of interest to the scramjet research community, but to also begin to understand how this capability can best be used to augment standard Reynolds-averaged simulations. The numerical errors were quantified for the steady-state simulations, and at least qualitatively assessed for the scale-resolving simulations prior to making any claims of predictive accuracy relative to the measurements. The steady-state Reynolds-averaged results displayed a high degree of variability when comparing the flameholder fuel distributions obtained from each turbulence model. This prompted the consideration of applying the higher-fidelity scale-resolving simulations as a surrogate "truth" model to calibrate the Reynolds-averaged closures in a non-reacting setting prior to their use for the combusting simulations. In general, the Reynolds-averaged velocity profile predictions at the lowest fueling level matched the particle imaging measurements almost as well as was observed for the non-reacting condition. However, the velocity field predictions proved to be more sensitive to the flameholder fueling rate than was indicated in the measurements.

  20. The behaviour of CAGR moderator and sleeve graphites radiolytically oxidised to high weight loss in inhibited coolant gas compositions

    International Nuclear Information System (INIS)

    Schofield, P.; Fitzgerald, B.; Ketchen, J.

    1987-01-01

    Gilsocarbon graphites were irradiated to high weight losses in three different CO 2 based coolants. The experimental data is tested against a model which interprets the gas phase chemistry and pore geometry and allows weight loss and gas flow properties to be calculated. The observed changes of oxidation rate with dose were successfully predicted from the model. An empirical relationship was also derived which was shown to fit data for moderator, sleeve and special pore structure graphites. Changes in graphite permeability and diffusivity were predicted by the model, and also by other simplified, more approximate methods. The model based upon the measured transport pore spectrum was shown to be the best with other methods proving adequate to moderate doses. (author)

  1. Vocabulary Use by Low, Moderate, and High ASL-Proficient Writers Compared to Hearing ESL and Monolingual Speakers.

    Science.gov (United States)

    Singleton, Jenny L; Morgan, Dianne; DiGello, Elizabeth; Wiles, Jill; Rivers, Rachel

    2004-01-01

    The written English vocabulary of 72 deaf elementary school students of various proficiency levels in American Sign Language (ASL) was compared with the performance of 60 hearing English-as-a-second-language (ESL) speakers and 61 hearing monolingual speakers of English, all of similar age. Students were asked to retell "The Tortoise and the Hare" story (previously viewed on video) in a writing activity. Writing samples were later scored for total number of words, use of words known to be highly frequent in children's writing, redundancy in writing, and use of English function words. All deaf writers showed significantly lower use of function words as compared to their hearing peers. Low-ASL-proficient students demonstrated a highly formulaic writing style, drawing mostly on high-frequency words and repetitive use of a limited range of function words. The moderate- and high-ASL-proficient deaf students' writing was not formulaic and incorporated novel, low-frequency vocabulary to communicate their thoughts. The moderate- and high-ASL students' performance revealed a departure from findings one might expect based on previous studies with deaf writers and their vocabulary use. The writing of the deaf writers also differed from the writing of hearing ESL speakers. Implications for deaf education and literacy instruction are discussed, with special attention to the fact that ASL-proficient, deaf second-language learners of English may be approaching English vocabulary acquisition in ways that are different from hearing ESL learners.

  2. Effects of repetitive subconcussive head trauma on the neuropsychological test performance of high school athletes: A comparison of high, moderate, and low contact sports.

    Science.gov (United States)

    Tsushima, William T; Ahn, Hyeong Jun; Siu, Andrea M; Yoshinaga, Kara; Choi, So Yung; Murata, Nathan M

    2018-02-02

    The aim of this study was to examine the neuropsychological test results of non-concussed high school athletes playing at three different levels of contact sports. Based on the concussion risk data of 12 different sports, a High Contact group (n=2819; wrestling/martial arts, cheerleading, track and field, football), a Moderate Contact group (n=2323; softball, basketball, soccer), and a Low Contact group (n=1580; baseball, volleyball, water polo, tennis, cross-country) were formed and compared in terms of their scores on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). The results revealed that the High Contact group obtained small but statistically poorer performances in ImPACT Visual Memory, Visual Motor Speed, Impulse Control, and Total Symptom scores compared to the Moderate and Low Contact groups. The High Contact group also had poorer Reaction Time scores compared to the Low Contact group. No differences between the Moderate and Low Contact groups were noted. The findings, along with prior similar results, tentatively raise concerns that participant in high contact sports, exposed to repetitive subconcussive head trauma, may be at greater risk for lowered neuropsychological functioning and increased symptoms, compared to other high school athletes. In view of the preliminary nature of this investigation, more research into the effects of frequent head impacts in high school sports is strongly recommended.

  3. Men and Women Exhibit Similar Acute Hypotensive Responses After Low, Moderate, or High-Intensity Plyometric Training.

    Science.gov (United States)

    Ramírez-Campillo, Rodrigo; Abad-Colil, Felipe; Vera, Maritza; Andrade, David C; Caniuqueo, Alexis; Martínez-Salazar, Cristian; Nakamura, Fábio Y; Arazi, Hamid; Cerda-Kohler, Hugo; Izquierdo, Mikel; Alonso-Martínez, Alicia M

    2016-01-01

    The aim of this study was to compare the acute effects of low-, moderate-, high-, and combined-intensity plyometric training on heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and rate-pressure product (RPP) cardiovascular responses in male and female normotensive subjects. Fifteen (8 women) physically active normotensive subjects participated in this study (age 23.5 ± 2.6 years, body mass index 23.8 ± 2.3 kg · m(-2)). Using a randomized crossover design, trials were conducted with rest intervals of at least 48 hours. Each trial comprised 120 jumps, using boxes of 20, 30, and 40 cm for low, moderate, and high intensity, respectively. For combined intensity, the 3 height boxes were combined. Measurements were taken before and after (i.e., every 10 minutes for a period of 90 minutes) each trial. When data responses of men and women were combined, a mean reduction in SBP, DBP, and RPP was observed after all plyometric intensities. No significant differences were observed pre- or postexercise (at any time point) for HR, SBP, DBP, or RPP when low-, moderate-, high-, or combined-intensity trials were compared. No significant differences were observed between male and female subjects, except for a higher SBP reduction in women (-12%) compared with men (-7%) after high-intensity trial. Although there were minor differences across postexercise time points, collectively, the data demonstrated that all plyometric training intensities can induce an acute postexercise hypotensive effect in young normotensive male and female subjects.

  4. An Examination of the Moderating Effects of the High School Socioeconomic Context on College Enrollment

    Science.gov (United States)

    Engberg, Mark E.; Wolniak, Gregory C.

    2014-01-01

    Drawing on a nationally representative sample of high school seniors from the Educational Longitudinal Survey of 2002 (ELS), this study examines the influence of the high school socioeconomic context on students' decisions to attend two-and four-year postsecondary institutions. The results provide evidence of resource imbalances based on…

  5. The relationship between dental caries and dental fluorosis in areas with moderate- and high-fluoride drinking water in Ethiopia.

    Science.gov (United States)

    Wondwossen, Fantaye; Astrøm, Anne Nordrehaug; Bjorvatn, Kjell; Bårdsen, Asgeir

    2004-10-01

    The aim of the study is to assess the relationship between caries and dental fluorosis in Ethiopian children living in Rift Valley areas known for endemic fluorosis. A total of 306 children (12-15 years old), selected from areas with moderate (0.3-2.2 mg/l), or high (10-14 mg/l) fluoride concentration in the drinking water were interviewed and examined for caries and dental fluorosis. Scorings were recorded according to the DMF system, and the Thylstrup-Fejerskov (TF) Index. Prevalence of dental fluorosis (TF-score > or = 1) was 91.8% (moderate area) and 100% (high-fluoride area). The corresponding caries prevalence and mean DMFT in the areas were 45.3% versus 61.6%, and 1.2 versus 1.8, respectively. Age and severity of dental fluorosis were found to be independent predictors for DMFT > or = 1. When compared with 12-year olds with TF-scores 0-4, odds ratios were 3.0 (95% CI 1.6-5.7) and 2.0 (95% CI 1.2-3.2) if TF-scores were > or = 5 and age 13-15 years, respectively. A positive relationship between caries and fluorosis was observed across tooth types in both areas. The percentage of children with DMFT > or = 1 was highest in groups with TF-score > or = 5 in the second molar, followed by the first molar. The present findings indicate that the second molar is the tooth most severely affected by dental fluorosis and dental caries. Dental caries increased with increasing severity of dental fluorosis, both in moderate- and high-fluoride areas. Thus, a positive relationship between dental caries and dental fluorosis was observed across various tooth types, in both areas. Copyright Blackwell Munksgaard, 2004

  6. Reynolds analogy for the Rayleigh problem at various flow modes.

    Science.gov (United States)

    Abramov, A A; Butkovskii, A V

    2016-07-01

    The Reynolds analogy and the extended Reynolds analogy for the Rayleigh problem are considered. For a viscous incompressible fluid we derive the Reynolds analogy as a function of the Prandtl number and the Eckert number. We show that for any positive Eckert number, the Reynolds analogy as a function of the Prandtl number has a maximum. For a monatomic gas in the transitional flow regime, using the direct simulation Monte Carlo method, we investigate the extended Reynolds analogy, i.e., the relation between the shear stress and the energy flux transferred to the boundary surface, at different velocities and temperatures. We find that the extended Reynolds analogy for a rarefied monatomic gas flow with the temperature of the undisturbed gas equal to the surface temperature depends weakly on time and is close to 0.5. We show that at any fixed dimensionless time the extended Reynolds analogy depends on the plate velocity and temperature and undisturbed gas temperature mainly via the Eckert number. For Eckert numbers of the order of unity or less we generalize an extended Reynolds analogy. The generalized Reynolds analogy depends mainly only on dimensionless time for all considered Eckert numbers of the order of unity or less.

  7. High quality draft genome sequence of the moderately halophilic bacterium Pontibacillus yanchengensis Y32(T) and comparison among Pontibacillus genomes.

    Science.gov (United States)

    Huang, Jing; Qiao, Zi Xu; Tang, Jing Wei; Wang, Gejiao

    2015-01-01

    Pontibacillus yanchengensis Y32(T) is an aerobic, motile, Gram-positive, endospore-forming, and moderately halophilic bacterium isolated from a salt field. In this study, we describe the features of P. yanchengensis strain Y32(T) together with a comparison with other four Pontibacillus genomes. The 4,281,464 bp high-quality-draft genome of strain Y32(T) is arranged into 153 contigs containing 3,965 protein-coding genes and 77 RNA encoding genes. The genome of strain Y32(T) possesses many genes related to its halophilic character, flagellar assembly and chemotaxis to support its survival in a salt-rich environment.

  8. Short-term moderate intensive high volume training program provides aerobic endurance benefit in wheelchair basketball players.

    Science.gov (United States)

    Skucas, Kestutis; Pokvytyte, Vaida

    2017-04-01

    The aim of this paper was to investigate the effect of short-term period, moderate intensity and high volume endurance training on physiological variables in elite wheelchair basketball players. Eight wheelchair basketball players were examined. The subjects participated in a two-week intervention program of mainly two training types: wheelchair basketball and wheelchair driving endurance training. The subjects performed the continuously increasing cycling exercise (CCE) at the constant 60 rpm arm cranking speed at the beginning of the program and after two weeks of the program. The initial workload was 20 W, then the workload was increased by 2 W every 5 seconds until fatigue. The post training of the wheelchair basketball group in the study showed a significant improvement in the peak oxygen uptake (VO2peak) and the peak power output (POpeak). VO2peak increased by 9% from 2.32±0.16 L/min to 2.53±0.2 L/min (Pbasketball squad had relatively high levels of aerobic fitness prior to participating in the endurance training program. Nevertheless, the high-volume, moderate-intensity, short-term training program, which evolved over the two-weeks period, resulted in the improvement of the athlete's aerobic endurance. The ventilatory threshold (VT) and the second ventilatory threshold (VT2) are good markers for aerobic capacity of wheelchair athletes.

  9. Energy Saving High-Capacity Moderate Pressure Carbon Dioxide Storage System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Our approach to high-pressure carbon dioxide storage will directly address the challenges associated with storage of compressed carbon dioxide - the need to reduce...

  10. Reynolds averaged turbulence modelling using deep neural networks with embedded invariance

    International Nuclear Information System (INIS)

    Ling, Julia; Kurzawski, Andrew; Templeton, Jeremy

    2016-01-01

    There exists significant demand for improved Reynolds-averaged Navier–Stokes (RANS) turbulence models that are informed by and can represent a richer set of turbulence physics. This paper presents a method of using deep neural networks to learn a model for the Reynolds stress anisotropy tensor from high-fidelity simulation data. A novel neural network architecture is proposed which uses a multiplicative layer with an invariant tensor basis to embed Galilean invariance into the predicted anisotropy tensor. It is demonstrated that this neural network architecture provides improved prediction accuracy compared with a generic neural network architecture that does not embed this invariance property. Furthermore, the Reynolds stress anisotropy predictions of this invariant neural network are propagated through to the velocity field for two test cases. For both test cases, significant improvement versus baseline RANS linear eddy viscosity and nonlinear eddy viscosity models is demonstrated.

  11. Reynolds averaged simulation of unsteady separated flow

    International Nuclear Information System (INIS)

    Iaccarino, G.; Ooi, A.; Durbin, P.A.; Behnia, M.

    2003-01-01

    The accuracy of Reynolds averaged Navier-Stokes (RANS) turbulence models in predicting complex flows with separation is examined. The unsteady flow around square cylinder and over a wall-mounted cube are simulated and compared with experimental data. For the cube case, none of the previously published numerical predictions obtained by steady-state RANS produced a good match with experimental data. However, evidence exists that coherent vortex shedding occurs in this flow. Its presence demands unsteady RANS computation because the flow is not statistically stationary. The present study demonstrates that unsteady RANS does indeed predict periodic shedding, and leads to much better concurrence with available experimental data than has been achieved with steady computation

  12. Postoperative Corneal Asphericity in Low, Moderate, and High Myopic Eyes After Transepithelial PRK Using a New Pulse Allocation.

    Science.gov (United States)

    Lin, David T C; Holland, Simon P; Verma, Shwetabh; Hogden, John; Arba-Mosquera, Samuel

    2017-12-01

    To evaluate the postoperative asphericity in low, moderate, and high myopic eyes after combined transepithelial photorefractive keratectomy and SmartSurf ACE treatment (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). In this retrospective case series, the outcomes of myopic SmartSurf ACE were evaluated at 3 months postoperatively in 106 eyes and divided into low (less than -4.125 diopters [D]), moderate (-4.125 to -6.25 D), and high (more than -6.25 D) myopia groups. In all cases, standard examinations and preoperative and postoperative corneal topography (SCHWIND Sirius) were performed. The analysis comprised evaluating the change in asphericity versus planned correction, comparing expected and achieved postoperative asphericity for all eyes, and comparison of the three groups in terms of the preoperative and postoperatively expected and achieved asphericity. RESULTS At 3 months postoperatively, the low myopia group (n = 33) improved average negative asphericity (Q = -0.04 ± 0.17 preoperative vs -0.19 ± 0.20 postoperative, P .10), but showed significant differences postoperatively (P < .007). The cohort's average preoperative corrected distance visual acuity was 0.01 ± 0.04 logMAR (range: 0.0 to 0.18 logMAR) and uncorrected distance visual acuity was 0.03 ± 0.08 logMAR (range: -0.12 to 0.40 logMAR) 3 months postoperatively. SmartSurf ACE maintained or slightly improved preoperative corneal asphericity for low to moderate myopic corrections (up to -6.00 D). This may provide advantages in the quality of vision and the onset of presbyopic symptoms after laser refractive surgery in myopic patients. [J Refract Surg. 2017;33(12):820-826.]. Copyright 2017, SLACK Incorporated.

  13. High risks of lung disease associated with early-life and moderate lifetime arsenic exposure in northern Chile

    Energy Technology Data Exchange (ETDEWEB)

    Steinmaus, Craig, E-mail: craigs@berkeley.edu [Arsenic Health Effects Research Program, UC Berkeley School of Public Health, Berkeley, CA (United States); Ferreccio, Catterina; Acevedo, Johanna [School of Medicine, Pontificia Universidad Católica de Chile, Santiago (Chile); Advanced Center for Chronic Diseases (ACCDiS), FONDAP, Santiago (Chile); Balmes, John R [Arsenic Health Effects Research Program, UC Berkeley School of Public Health, Berkeley, CA (United States); Department of Medicine, University of California, San Francisco, San Francisco, CA (United States); Liaw, Jane [Arsenic Health Effects Research Program, UC Berkeley School of Public Health, Berkeley, CA (United States); Troncoso, Patricia [Laboratorio de Anatomía Patológica Dra. Patricia Troncoso, Iquique (Chile); Hospital Felix Bulnes, Departmento de Anatomía Patológica, Santiago (Chile); Dauphiné, David C [Arsenic Health Effects Research Program, UC Berkeley School of Public Health, Berkeley, CA (United States); Nardone, Anthony [Global Health Sciences Program, University of California, San Francisco, San Francisco, CA (United States); Smith, Allan H [Arsenic Health Effects Research Program, UC Berkeley School of Public Health, Berkeley, CA (United States)

    2016-12-15

    Background: Arsenic in drinking water has been associated with increases in lung disease, but information on the long-term impacts of early-life exposure or moderate exposure levels are limited. Methods: We investigated pulmonary disease and lung function in 795 subjects from three socio-demographically similar areas in northern Chile: Antofagasta, which had a well-described period of high arsenic water concentrations (860 μg/L) from 1958 to 1970; Iquique, which had long-term arsenic water concentrations near 60 μg/L; and Arica, with long-term water concentrations ≤ 10 μg/L. Results: Compared to adults never exposed > 10 μg/L, adults born in Antofagasta during the high exposure period had elevated odds ratios (OR) of respiratory symptoms (e.g., OR for shortness of breath = 5.56, 90% confidence interval (CI): 2.68–11.5), and decreases in pulmonary function (e.g., 224 mL decrease in forced vital capacity in nonsmokers, 90% CI: 97–351 mL). Subjects with long-term exposure to arsenic water concentrations near 60 μg/L also had increases in some pulmonary symptoms and reduced lung function. Conclusions: Overall, these findings provide new evidence that in utero or childhood arsenic exposure is associated with non-malignant pulmonary disease in adults. They also provide preliminary new evidence that long-term exposures to moderate levels of arsenic may be associated with lung toxicity, although the magnitude of these latter findings were greater than expected and should be confirmed. - Highlights: • Based on its unique geology, lifetime arsenic exposure can be assessed in north Chile. • Signs and symptoms of lung disease were associated with early-life arsenic exposure. • Evidence of lung disease was also associated with moderate arsenic exposure.

  14. HvZIP7 mediates zinc accumulation in barley (Hordeum vulgare) at moderately high zinc supply

    DEFF Research Database (Denmark)

    Tiong, Jingwen; Mcdonald, Glenn K.; Genc, Yusuf

    2014-01-01

    Summary: High expression of zinc (Zn)-regulated, iron-regulated transporter-like protein (ZIP) genes increases root Zn uptake in dicots, leading to high accumulation of Zn in shoots. However, none of the ZIP genes tested previously in monocots could enhance shoot Zn accumulation. In this report...... were also generated to further understand the functions of HvZIP7 in metal transport. HvZIP7 is strongly induced by Zn deficiency, primarily in vascular tissues of roots and leaves, and its protein was localized in the plasma membrane. These properties are similar to its closely related homologs...... in dicots. Overexpression of HvZIP7 in barley plants increased Zn uptake when moderately high concentrations of Zn were supplied. Significantly, there was a specific enhancement of shoot Zn accumulation, with no measurable increase in iron (Fe), manganese (Mn), copper (Cu) or cadmium (Cd). HvZIP7 displays...

  15. Concerning moderate seniority mixing and the high spin states of some N=50 isotones

    International Nuclear Information System (INIS)

    Amusa, A.

    1987-11-01

    The high spin states of some N=50 isotones are studied in a shell model scheme involving the restriction of the valence nucleons to 2p 1/2 and 1g 9/2 orbits as well as the use of an interaction that has slight seniority non-conservation. Our results indicate that the high spin states of these nuclei, in direct contrast to their low spin states, have extra-(2p 1/2 ,1g 9/2 ) n space contributions that support violation of seniority conservation. (author). 17 refs, 2 figs, 1 tab

  16. Workshop on nuclear structure at moderate and high spin: Slide report

    International Nuclear Information System (INIS)

    1986-10-01

    The workshop was scheduled to coincide with the beginning of operation of a number of large arrays of Compton-suppressed germanium detectors. The workshop was divided into 14 sessions containing 3 presentations each. The topics of these sessions were superdeformation, heavy rare earths, single-particle configurations, band termination, continuum properties, light rare-earths, new techniques, high temperatures, transfer reactions, transition region, shapes, lifetimes, and moments. This publication consists of the slides used in all of the presentations at the workshop

  17. Comparison Of A Neutron Kinetics Parameter For A Polyethylene Moderated Highly Enriched Uranium System

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, IV, George Espy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Goda, Joetta Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Grove, Travis Justin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sanchez, Rene Gerardo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-04-17

    This paper examines the comparison of MCNP® code’s capability to calculate kinetics parameters effectively for a thermal system containing highly enriched uranium (HEU). The Rossi-α parameter was chosen for this examination because it is relatively easy to measure as well as easy to calculate using MCNP®’s kopts card. The Rossi-α also incorporates many other parameters of interest in nuclear kinetics most of which are more difficult to precisely measure. The comparison looks at two different nuclear data libraries for comparison to the experimental data. These libraries are ENDF/BVI (.66c) and ENDF/BVII (.80c).

  18. Moderator's view: High-volume plasma exchange: pro, con and consensus.

    Science.gov (United States)

    Kaplan, Andre A

    2017-09-01

    I have been asked to comment on the pro and con opinions regarding high-volume plasma exchange. The authors of both positions have provided cogent arguments and a reasonable approach to choosing the exchange volume for any given therapeutic plasma exchange. The major issue of relevance in this discussion is the nature of the toxins targeted for removal. These parameters include molecular weight, the apparent volume of distribution, the degree of protein binding, the biologic and chemical half-life, and the severity and rapidity of its toxicity. © The Author 2017. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  19. Low-Reynolds Number Effects in Ventilated Rooms

    DEFF Research Database (Denmark)

    Davidson, Lars; Nielsen, Peter V.; Topp, Claus

    In the present study, we use Large Eddy Simulations (LES) which is a suitable method for simulating the flow in ventilated rooms at low Reynolds number.......In the present study, we use Large Eddy Simulations (LES) which is a suitable method for simulating the flow in ventilated rooms at low Reynolds number....

  20. On Reynolds number dependence of micro-ramp-induced transition

    NARCIS (Netherlands)

    Ye, Q.; Schrijer, F.F.J.; Scarano, F.

    2018-01-01

    The variation of transitional flow features past a micro-ramp is investigated when the Reynolds number is decreased approaching the critical regime. Experiments are conducted in the incompressible flow spanning from supercritical to subcritical roughness-height-based Reynolds number ( , 730, 460

  1. A moderated mediated path analysis of factors influencing student performance on a standardized high-stakes science test

    Science.gov (United States)

    Pelkey, Ramona K.

    Gender, ethnicity, family economic status, reading score, mathematics score, and number of science semesters successfully completed were examined for their contributory role to a student's science score on a high-stakes, high school exit examination. Path analysis and analysis of variance procedures were used to quantify each variable's influence on science score. Gender, ethnicity, and family economic status were found to be moderators while reading proved to mediate within the model. The path model was created using a calibration sample and cross-validated using a hold-out validation sample. Bootstrapping was used to verify the goodness of fit of the model. A predictive equation explained 66% (R2 = .66) of the variance in observed TAKS science score.

  2. A Discussion of Low Reynolds Number Flow for the Two-Dimensional Benchmark Test Case

    DEFF Research Database (Denmark)

    Weng, Miaocheng; Nielsen, Peter V.; Liu, Li

    The use of CFD in ventilation research has arrived to a high level, but there are some conditions in the general CFD procedure which do not apply to all situations in the ventilation research. An example of this isthe turbulence models in Reynolds-averaged Navier-Stokes equations, i.e. (RANS...

  3. Gravitational sedimentation of cloud of solid spherical particles at small Reynolds numbers

    Directory of Open Access Journals (Sweden)

    Arkhipov Vladimir

    2015-01-01

    Full Text Available The experimental results of study of gravitational sedimentation of highly-concentrated systems of solid spherical particles at small Reynolds numbers Re<1 are presented. Empirical equation for drag coefficient of the particle assembly has been obtained. The influence of initial particle concentration in the cloud on its dynamics and velocity has been analysed.

  4. High-order harmonic generation in clusters irradiated by an infrared laser field of moderate intensity

    International Nuclear Information System (INIS)

    Zaretsky, D F; Korneev, Ph; Becker, W

    2010-01-01

    Extending the Lewenstein model of high-order harmonic generation (HHG) in a laser-irradiated atom, a model of HHG in a cluster is formulated. The constituent atoms of the cluster are assumed to be partly ionized. An electron freed through tunnelling may recombine either with its parent ion or with another ion in the vicinity. Harmonics due to the former process are coherent within the same cluster and may be coherent between different clusters, while harmonics due to the latter process are incoherent. Depending on the density of available ions, the incoherent mechanism may dominate the total harmonic yield, and the harmonic spectrum, which extends to higher energies, has a less distinct cutoff and an enhanced low-energy part.

  5. Effects of Dimple Depth and Reynolds Number on the Flow and Heat Transfer in a Dimpled Channel

    International Nuclear Information System (INIS)

    Ahn, Joon; Lee, Young Ok; Lee, Joon Sik

    2007-01-01

    A Large Eddy Simulation (LES) has been conducted for the flow and heat transfer in a dimpled channel. Two dimple depths of 0.2 and 0.3 times of the dimple print diameter (= D) have been compared at the bulk Reynolds number of 20,000. Three Reynolds numbers of 5,000, 10,000 and 20,000 have been studied, while the dimple depth is kept as 0.2 D. With the deeper dimple, the flow reattachment occurs father downstream inside the dimple, so that the heat transfer is not as effectively enhanced as the case with shallow ones. At the low Reynolds number of 5,000, the Nusselt number ratio is as high as those for the higher Reynolds number, although the value of heat transfer coefficient decreases because of the weak shear layer vortices

  6. Reactivity and reaction rate ratio changes with moderator voidage in a light water high converter reactor lattice

    International Nuclear Information System (INIS)

    Chawla, R.; Gmuer, K.; Hager, H.; Seiler, R.

    1986-01-01

    Integral reaction rate ratios and other k ∞ related parameters have been measured in the first three cores of the experimental program on light water high converter reactor (LWHCR) test lattices in the PROTEUS reactor. The reference tight-pitch lattice consisted of two rod types, with an average fissile-plutonium enrichment of 6% and a fuel/moderator ratio of 2.0. The moderators were H 2 O, Dowtherm (simulating an H 2 O voidage of 42.5%), and air (100% void). Comparisons of the measured parameters have been made with calculational results based mainly on the use of two separate codes and their associated data libraries, namely, WIMS-D and EPRI-CPM. A reconstruction of individual components of the k-infinity void coefficient has been carried out on the basis of the measured changes with voidage of the various reaction rate ratios, as well as of k-infinity itself. The subsequent more detailed comparisons between experiment and calculation should provide a useful basis for resolving the conflicting calculational results that have been reported in the past for the void coefficient characteristics of LWHCRs. (author)

  7. Evidence for mass loss at moderate to high velocity in Be stars

    International Nuclear Information System (INIS)

    Snow, T.P. Jr.; Marlborough, J.M.

    1976-01-01

    Ultraviolet spectra of intermediate resolution have been obtained with Copernicus of 12 objects classified as Be or shell stars, and 19 additional early B dwarfs. Some of these spectra show marked asymmetries in certain resonance lines, especially the Si iv doublet at 1400 A, indicating the presence in some cases of outflowing material with maximum velocities of nearly 1000 km s -1 . Direct evidence for mass loss at these velocities is seen for the first time in dwarf stars as late as B1.5; the only objects later than B0.5 which show this effect are Be or shell stars. Among the stars considered there is a correlation between the presence of mass-loss effects and projected rotational velocity, suggesting that the ultraviolet flux from B1-B2 dwarfs is sufficient to drive high-velocity stellar winds only if rotation effects reduce the effective gravity near the equator. The mass loss rate for one of the most active Be stars, 59 Cyg, is crudely estimated to be 10 -10 --10 -9 M/sub sun/ yr -1 . The data are suggestive that the extended atmospheres associated with Be star phenomena may be formed by mass ejection

  8. Evidence for mass loss at moderate to high velocity in Be stars

    Science.gov (United States)

    Snow, T. P., Jr.; Marlborough, J. M.

    1976-01-01

    Ultraviolet spectra of intermediate resolution have been obtained with Copernicus for 12 objects classified as Be or shell stars and for 19 additional early B dwarfs. Some of these spectra show marked asymmetries in certain resonance lines, especially the Si IV doublet at 1400 A, indicating the presence in some cases of outflowing material with maximum velocities of nearly 1000 km/s. Direct evidence for mass loss at these velocities is seen for the first time in dwarf stars as late as B1.5; the only objects later than B0.5 which show this effect are Be or shell stars. Among the stars considered, there is a correlation between the presence of mass-loss effects and projected rotational velocity, suggesting that the ultraviolet flux from B1-B2 dwarfs is sufficient to drive high-velocity stellar winds only if rotational effects reduce the effective gravity near the equator. The mass-loss rate for one of the most active Be stars, 59 Cyg, is crudely estimated to be one billionth or one ten-billionth of a solar mass per year. The data suggest that the extended atmospheres associated with Be-star phenomena may be formed by mass ejection.

  9. Absorption of fast waves at moderate to high ion cyclotron harmonics on DIII-D

    International Nuclear Information System (INIS)

    Pinsker, R.I.; Porkolab, M.; Heidbrink, W.W.; Luo, Y.; Petty, C.C.; Prater, R.; Choi, M.; Schaffner, D.A.; Baity, F.W.; Fredd, E.; Hosea, J.C.; Harvey, R.W.; Smirnov, A.P.; Murakami, M.; Zeeland, M.A. Van

    2006-01-01

    The absorption of fast Alfven waves (FW) by ion cyclotron harmonic damping in the range of harmonics from 4th to 8th is studied theoretically and with experiments in the DIII-D tokamak. A formula for linear ion cyclotron absorption on ions with an arbitrary distribution function which is symmetric about the magnetic field is used to estimate the single-pass damping for various cases of experimental interest. It is found that damping on fast ions from neutral beam injection can be significant even at the 8th harmonic if the fast ion beta, the beam injection energy and the background plasma density are high enough and the beam injection geometry is appropriate. The predictions are tested in several L-mode experiments in DIII-D with FW power at 60 MHz and at 116 MHz. It is found that 4th and 5th harmonic absorption of the 60 MHz power on the beam ions can be quite strong, but 8th harmonic absorption of the 116 MHz power appears to be weaker than expected. The linear modelling predicts a strong dependence of the 8th harmonic absorption on the initial pitch-angle of the injected beam, which is not observed in the experiment. Possible explanations of the discrepancy are discussed

  10. Safety analysis of a high temperature supercritical pressure light water cooled and moderated reactor

    International Nuclear Information System (INIS)

    Ishiwatari, Y.; Oka, Y.; Koshizuka, S.

    2002-01-01

    A safety analysis code for a high temperature supercritical pressure light water cooled reactor (SCLWR-H) with water rods cooled by descending flow, SPRAT-DOWN, is developed. The hottest channel, a water rod, down comer, upper and lower plenums, feed pumps, etc. are modeled as junction of nodes. Partial of the feed water flows downward from the upper dome of the reactor pressure vessel to the water rods. The accidents analyzed here are total loss of feed water flow, feed water pump seizure, and control rods ejection. All the accidents satisfy the criteria. The accident event at which the maximum cladding temperature is the highest is total loss of feedwater flow. The transients analyzed here are loss of feed water heating, inadvertent start-up of an auxiliary water supply system, partial loss of feed water flow, loss of offsite power, loss of load, and abnormal withdrawal of control rods. All the transients satisfied the criteria. The transient event for which the maximum cladding temperature is the highest is control rod withdrawal at normal operation. The behavior of loss of load transient is different from that of BWR. The power does not increase because loss of flow occurs and the density change is small. The sensitivities of the system behavior to various parameters during transients and accidents are analyzed. The parameters having strong influence are the capacity of the auxiliary water supply system, the coast down time of the main feed water pumps, and the time delay of the main feed water pumps trip. The control rod reactivity also has strong influence. (authors)

  11. Retirement Sequences of Older Americans: Moderately Destandardized and Highly Stratified Across Gender, Class, and Race.

    Science.gov (United States)

    Calvo, Esteban; Madero-Cabib, Ignacio; Staudinger, Ursula M

    2017-06-06

    A destandardization of labor-force patterns revolving around retirement has been observed in recent literature. It is unclear, however, to which degree and of which kind. This study looked at sequences rather than individual statuses or transitions and argued that differentiating older Americans' retirement sequences by type, order, and timing and considering gender, class, and race differences yields a less destandardized picture. Sequence analysis was employed to analyze panel data from the Health and Retirement Study (HRS) for 7,881 individuals observed 6 consecutive times between ages 60-61 and 70-71. As expected, types of retirement sequences were identified that cannot be subsumed under the conventional model of complete retirement from full-time employment around age 65. However, these retirement sequences were not entirely destandardized, as some irreversibility and age-grading persisted. Further, the degree of destandardization varied along gender, class, and race. Unconventional sequences were archetypal for middle-level educated individuals and Blacks. Also, sequences for women and individuals with lower education showed more unemployment and part-time jobs, and less age-grading. A sequence-analytic approach that models group differences uncovers misjudgments about the degree of destandardization of retirement sequences. When a continuous process is represented as individual transitions, the overall pattern of retirement sequences gets lost and appears destandardized. These patterns get further complicated by differences in social structures by gender, class, and race in ways that seem to reproduce advantages that men, more highly educated individuals, and Whites enjoy in numerous areas over the life course. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Hybrid Reynolds-Averaged/Large Eddy Simulation of a Cavity Flameholder; Assessment of Modeling Sensitivities

    Science.gov (United States)

    Baurle, R. A.

    2015-01-01

    Steady-state and scale-resolving simulations have been performed for flow in and around a model scramjet combustor flameholder. The cases simulated corresponded to those used to examine this flowfield experimentally using particle image velocimetry. A variety of turbulence models were used for the steady-state Reynolds-averaged simulations which included both linear and non-linear eddy viscosity models. The scale-resolving simulations used a hybrid Reynolds-averaged / large eddy simulation strategy that is designed to be a large eddy simulation everywhere except in the inner portion (log layer and below) of the boundary layer. Hence, this formulation can be regarded as a wall-modeled large eddy simulation. This effort was undertaken to formally assess the performance of the hybrid Reynolds-averaged / large eddy simulation modeling approach in a flowfield of interest to the scramjet research community. The numerical errors were quantified for both the steady-state and scale-resolving simulations prior to making any claims of predictive accuracy relative to the measurements. The steady-state Reynolds-averaged results showed a high degree of variability when comparing the predictions obtained from each turbulence model, with the non-linear eddy viscosity model (an explicit algebraic stress model) providing the most accurate prediction of the measured values. The hybrid Reynolds-averaged/large eddy simulation results were carefully scrutinized to ensure that even the coarsest grid had an acceptable level of resolution for large eddy simulation, and that the time-averaged statistics were acceptably accurate. The autocorrelation and its Fourier transform were the primary tools used for this assessment. The statistics extracted from the hybrid simulation strategy proved to be more accurate than the Reynolds-averaged results obtained using the linear eddy viscosity models. However, there was no predictive improvement noted over the results obtained from the explicit

  13. A Review of the Reynolds Intellectual Assessment Scales, Second Edition, and Reynolds Intellectual Screening Test, Second Edition

    Science.gov (United States)

    McNicholas, Patrick J.; Floyd, Randy G.

    2017-01-01

    The Reynolds Intellectual Assessment Scales, Second Edition (RIAS-2; Reynolds & Kamphaus, 2015) is an intelligence test for those aged 3 to 94 years. It contains eight subtests designed to assess general intelligence, verbal and nonverbal intelligence, memory, and processing speed. The two subtests targeting processing speed are new to the…

  14. Effect of moderate versus high intensity interval exercise training on vascular function in inactive latin-american adults: a randomized clinical trial

    OpenAIRE

    Hernández Quiñonez, Paula Andrea

    2016-01-01

    Exercise training is effective for improving cardiometabolic health and physical fitness in inactive adults. However, limited research has been conducted on the optimal exercise training intensity for this population. We investigate the effect of moderate versus high intensity interval exercise training on vascular function and physical fitness in physically inactive adults. Twenty inactive adults were randomly allocated to receive either moderate intensity training (MCT group) or high intens...

  15. Rarefaction Effects in Low Reynolds Number Subsonic and Transonic Aerodynamics

    Science.gov (United States)

    Pekardan, Cem

    The quantification of rarefaction effects for low Reynolds number (Reefficient. It was also shown that when the Reynolds number of the flow decreased from 10,000 to 1,000, slip effects become dominant. The flow becomes fully rarefied at Re=10. Furthermore, rarefaction effects were quantified for the NACA 0007 and the NACA 2407 at 0 and 10 degrees of angle of attack to investigate the effects of thickness, camber, and the angle of attack. It was observed that flow separation due to increase in thickness resulted in higher rarefaction effects. It was concluded that thin airfoils with very smooth shape changes minimize continuum breakdown / rarefaction effects. Rarefied gas phenomena that only appear in low pressures (such as thermal effects) can be exploited for performance enhancement of applications in slightly rarefied aerodynamics. In this study, feasibility and advantages of using thermal control to reduce drag and mitigate vortex shedding for airfoils are studied. NACA 0012 airfoil with a temperature difference applied between the upper and the lower surface is simulated in the continuum regime with a Navier-Stokes solver and compared to experimental data for verification of parameters and turbulence modelling. At lower pressures, an elevated temperature on the bottom surface of the airfoil is investigated to create lift and understand the rarefaction effects. Continuum NS results were compared to the rarefied ES-BGK solver for the rarefaction effects. It was shown that an elevated temperature enhances the lift by 25 % and reduces the drag at high angles of attack. In the second part, a temperature gradient on the upper surface is applied and it was seen that drag is reduced by 4 % and vortex shedding frequency is reduced due to gradients introduced in the flow by thermal transpiration.

  16. Measurement of mass attenuation coefficients of moderate-to-high atomic-number elements at low photon energies

    International Nuclear Information System (INIS)

    Tajuddin, A.A.; Chong, C.S.; Shukri, A.; Bradley, D.A.

    1995-01-01

    Mass attenuation coefficients for 12 selected moderate-to-high atomic-number elements have been obtained from good-geometry measurements made at five 241 Am photon energies of significant emission intensity. Particular interest focuses on measured values for photon energies close to absorption edges. Comparisons with renormalized cross-section predictions indicate agreement to within stated error limits for the majority of cases. Significant discrepancies (> 10%) are noted for Ta at 17.8 and 26.3 keV and W at 59.5 keV. Some support for a discrepancy between measurement and theory for W in the region of 60 keV is found in the reported measurements of others. (author)

  17. Effect of moderate- versus high-intensity exercise on vascular function, biomarkers and quality of life in heart transplant recipients

    DEFF Research Database (Denmark)

    Dall, Christian H; Gustafsson, Finn; Christensen, Stefan B

    2015-01-01

    BACKGROUND: Growing evidence in long-term treatment of heart transplant (HTx) recipients indicates effects of high-intensity interval training (HIIT) on several parameters, including oxygen uptake, vascular function and psychological distress. In this study we compare the effect of HIIT vs...... continued moderate training (CON) on vascular function, biomarkers and health-related quality of life (HRQoL) in HTx recipients. METHODS: A randomized, controlled crossover trial of stable HTx recipients >12 months after transplantation was done on patients with 12 weeks of HIIT or 12 weeks of CON, followed...... by a 5-month washout and crossover. Outcomes included endothelial function, arterial stiffness, biomarkers, HRQoL and markers of anxiety and depression. RESULTS: Sixteen HTx recipients (mean age 52 years, 75% male) completed the study. HIIT increased VO2peak more than CON (between-group difference, p

  18. Holography of the QGP Reynolds number

    Science.gov (United States)

    McInnes, Brett

    2017-08-01

    The viscosity of the Quark-Gluon Plasma (QGP) is usually described holographically by the entropy-normalized dynamic viscosity η / s. However, other measures of viscosity, such as the kinematic viscosity ν and the Reynolds number Re, are often useful, and they too should be investigated from a holographic point of view. We show that a simple model of this kind puts an upper bound on Re for nearly central collisions at a given temperature; this upper bound is in very good agreement with the observational lower bound (from the RHIC facility). Furthermore, in a holographic approach using only Einstein gravity, η / s does not respond to variations of other physical parameters, while ν and Re can do so. In particular, it is known that the magnetic fields arising in peripheral heavy-ion collisions vary strongly with the impact parameter b, and we find that the holographic model predicts that ν and Re can also be expected to vary substantially with the magnetic field and therefore with b.

  19. Holography of the QGP Reynolds number

    Directory of Open Access Journals (Sweden)

    Brett McInnes

    2017-08-01

    Full Text Available The viscosity of the Quark–Gluon Plasma (QGP is usually described holographically by the entropy-normalized dynamic viscosity η/s. However, other measures of viscosity, such as the kinematic viscosity ν and the Reynolds number Re, are often useful, and they too should be investigated from a holographic point of view. We show that a simple model of this kind puts an upper bound on Re for nearly central collisions at a given temperature; this upper bound is in very good agreement with the observational lower bound (from the RHIC facility. Furthermore, in a holographic approach using only Einstein gravity, η/s does not respond to variations of other physical parameters, while ν and Re can do so. In particular, it is known that the magnetic fields arising in peripheral heavy-ion collisions vary strongly with the impact parameter b, and we find that the holographic model predicts that ν and Re can also be expected to vary substantially with the magnetic field and therefore with b.

  20. The Effects of Exercise on the Physical Fitness of High and Moderate-Low Functioning Older Adult Women

    Directory of Open Access Journals (Sweden)

    R. Christopher Mason

    2016-01-01

    Full Text Available Introduction. Understanding how exercise affects individuals with varying levels of functional ability will provide further insight into the role of exercise during the aging process. It will also aid in the development of exercise programs that are appropriate for a wider spectrum of older adults. Specifically it was the primary aim of this study to determine and compare the effects of 10 weeks of community-based exercise on the cardiovascular endurance, muscular strength, flexibility, and balance fitness components of older adult women with high and moderate-low levels of physical function. Methods. Participants were placed in either the high functioning (n=13 or moderate/low functioning (n=17 groups based on their level of physical functioning. Fitness components were measured by the Senior Fitness Test and physical function was determined by the Composite Physical Function scale. Results. The results of the 3 × 2 mixed ANOVA statistical analysis showed no significant interaction effect for time ⁎ group for any of the six subtests (chair stand, arm curls, 2-minute step, chair sit-and-reach, back scratch, and 6-foot up-and-go of the SFT. However, the main effect of time was significant for all fitness components and the main effect of group was significant for all fitness components except lower extremity flexibility. Discussion. Community-based exercise programs offering a variety of exercise types to people with varying levels of functional ability can be useful in maintaining or improving fitness and independence. These programs may also be capable of improving the self-efficacy of lower functioning older adults toward performing daily tasks.

  1. High-Throughput Screening for a Moderately Halophilic Phenol-Degrading Strain and Its Salt Tolerance Response

    Science.gov (United States)

    Lu, Zhi-Yan; Guo, Xiao-Jue; Li, Hui; Huang, Zhong-Zi; Lin, Kuang-Fei; Liu, Yong-Di

    2015-01-01

    A high-throughput screening system for moderately halophilic phenol-degrading bacteria from various habitats was developed to replace the conventional strain screening owing to its high efficiency. Bacterial enrichments were cultivated in 48 deep well microplates instead of shake flasks or tubes. Measurement of phenol concentrations was performed in 96-well microplates instead of using the conventional spectrophotometric method or high-performance liquid chromatography (HPLC). The high-throughput screening system was used to cultivate forty-three bacterial enrichments and gained a halophilic bacterial community E3 with the best phenol-degrading capability. Halomonas sp. strain 4-5 was isolated from the E3 community. Strain 4-5 was able to degrade more than 94% of the phenol (500 mg·L−1 starting concentration) over a range of 3%–10% NaCl. Additionally, the strain accumulated the compatible solute, ectoine, with increasing salt concentrations. PCR detection of the functional genes suggested that the largest subunit of multicomponent phenol hydroxylase (LmPH) and catechol 1,2-dioxygenase (C12O) were active in the phenol degradation process. PMID:26020478

  2. Incremental Theory of Intelligence Moderated the Relationship between Prior Achievement and School Engagement in Chinese High School Students.

    Science.gov (United States)

    Li, Ping; Zhou, Nan; Zhang, Yuchi; Xiong, Qing; Nie, Ruihong; Fang, Xiaoyi

    2017-01-01

    School engagement plays a prominent role in promoting academic accomplishments. In contrast to the relative wealth of research that examined the impact of students' school engagement on their academic achievement, considerably less research has investigated the effect of high school students' prior achievement on their school engagement. The present study examined the relationship between prior achievement and school engagement among Chinese high school students. Based on the Dweck's social-cognitive theory of motivation, we further examined the moderating effect of students' theories of intelligence (TOIs) on this relationship. A total of 4036 (2066 girls) students from five public high school enrolled in grades 10 reported their high school entrance exam achievement in Chinese, Math and English, school engagement, and TOIs. Results showed that (a) students' prior achievement predicted their behavioral, emotional, and cognitive engagement, respectively, and (b) the association between prior achievement and behavioral, emotional, and cognitive engagement is strong for students with an incremental theory but not for those with an entity theory in the emotional and cognitive engagement. These findings suggest that prior achievement and incremental theory were implicated in relation to adolescents' school engagement. Implications and future research directions were discussed.

  3. Incremental Theory of Intelligence Moderated the Relationship between Prior Achievement and School Engagement in Chinese High School Students

    Directory of Open Access Journals (Sweden)

    Ping Li

    2017-09-01

    Full Text Available School engagement plays a prominent role in promoting academic accomplishments. In contrast to the relative wealth of research that examined the impact of students’ school engagement on their academic achievement, considerably less research has investigated the effect of high school students’ prior achievement on their school engagement. The present study examined the relationship between prior achievement and school engagement among Chinese high school students. Based on the Dweck’s social-cognitive theory of motivation, we further examined the moderating effect of students’ theories of intelligence (TOIs on this relationship. A total of 4036 (2066 girls students from five public high school enrolled in grades 10 reported their high school entrance exam achievement in Chinese, Math and English, school engagement, and TOIs. Results showed that (a students’ prior achievement predicted their behavioral, emotional, and cognitive engagement, respectively, and (b the association between prior achievement and behavioral, emotional, and cognitive engagement is strong for students with an incremental theory but not for those with an entity theory in the emotional and cognitive engagement. These findings suggest that prior achievement and incremental theory were implicated in relation to adolescents’ school engagement. Implications and future research directions were discussed.

  4. Horace Lamb and Osborne Reynolds: Remarkable mancunians ... and their interactions

    International Nuclear Information System (INIS)

    Launder, B E

    2014-01-01

    The paper provides glimpses into the professional lives of arguably, the two outstanding fluid mechanicists of their time who were simultaneously professors at Owens College, Manchester. Their interactions with each other were sometimes amicable but, equally, sometimes testy and their views on their common professional subject differed radically. Reynolds was appointed to the Chair of Engineering in 1868 at the age of 25 against strong competition while Horace Lamb, graduating a decade after Reynolds, was appointed as the inaugural Professor of Applied Mathematics at the University of Adelaide where he stayed for nine years before being appointed to a chair at Owens College in 1885. Among their various interactions the most significant arose from Reynolds' famous 'Reynolds averaging' paper. That was sent for review by Lamb who was critical of the paper but finally recommended that a revised version be published since Reynolds had essentially invented the subject. Reynolds, in his turn, criticised Lamb's patronizing reference to engineers' approach to fluid mechanics in a draft revision of his book Hydrodynamics. Nevertheless, on Reynolds' death in 1912, it was Lamb who attended his funeral on behalf of the University and the Royal Society and who later wrote a moving, much cited obituary of him.

  5. Finite-Reynolds-number effects in turbulence using logarithmic expansions

    International Nuclear Information System (INIS)

    Sreenivasan, K.R.; Bershadskii, A.

    2006-12-01

    Experimental or numerical data in turbulence are invariably obtained at finite Reynolds numbers whereas theories of turbulence correspond to infinitely large Reynolds numbers. A proper merger of the two approaches is possible only if corrections for finite Reynolds numbers can be quantified. This paper heuristically considers examples in two classes of finite-Reynolds-number effects. Expansions in terms of logarithms of appropriate variables are shown to yield results in agreement with experimental and numerical data in the following instances: the third-order structure function in isotropic turbulence, the mixed-order structure function for the passive scalar and the Reynolds shear stress around its maximum point. Results suggestive of expansions in terms of the inverse logarithm of the Reynolds number, also motivated by experimental data, concern the tendency for turbulent structures to cluster along a line of observation and (more speculatively) for the longitudinal velocity derivative to become singular at some finite Reynolds number. We suggest an elementary hydrodynamical process that may provide a physical basis for the expansions considered here, but note that the formal justification remains tantalizingly unclear. (author)

  6. High-Dose-Rate Brachytherapy Alone for Localized Prostate Cancer in Patients at Moderate or High Risk of Biochemical Recurrence

    Energy Technology Data Exchange (ETDEWEB)

    Hoskin, Peter [Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Rojas, Ana, E-mail: arc03@btconnect.com [Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Lowe, Gerry; Bryant, Linda; Ostler, Peter; Hughes, Rob; Milner, Jessica; Cladd, Helen [Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom)

    2012-03-15

    Purpose: To evaluate genitourinary (GU) and gastrointestinal (GI) morbidity and biochemical control of disease in patients with localized prostate adenocarcinoma treated with escalating doses per fraction of high-dose rate brachytherapy alone. Methods and Materials: A total of 197 patients were treated with 34 Gy in four fractions, 36 Gy in four fractions, 31.5 Gy in three fractions, or 26 Gy in two fractions. Median follow-up times were 60, 54, 36, and 6 months, respectively. Results: Incidence of early Grade {>=} 3 GU morbidity was 3% to 7%, and Grade 4 was 0% to 4%. During the first 12 weeks, the highest mean International Prostate Symptom Score (IPSS) value was 14, and between 6 months and 5 years it was 8. Grade 3 or 4 early GI morbidity was not observed. The 3-year actuarial rate of Grade 3 GU was 3% to 16%, and was 3% to 7% for strictures requiring surgery (4-year rate). An incidence of 1% Grade 3 GI events was seen at 3 years. Late Grade 4 GU or GI events were not observed. At 3 years, 99% of patients with intermediate-risk and 91% with high-risk disease were free of biochemical relapse (log-rank p = 0.02). Conclusions: There was no significant difference in urinary and rectal morbidity between schedules. Biochemical control of disease in patients with intermediate and high risk of relapse was good.

  7. On the use of moderating material to enhance the feedback coefficients in SFR cores with high minor actinide content

    International Nuclear Information System (INIS)

    Merk, B.; Weiss, F. P.

    2012-01-01

    The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effecting sodium cooled fast reactor cores is described. The influence of the moderating material on the neutron spectrum, the power distribution, and the burnup distribution is shown. The consequences of the use of fine distributed moderating material into fuel assemblies with fuel configurations foreseen for minor actinide transmutation is analyzed and the transmutation efficiency is compared. The degradation of the feedback effects due to the insertion of minor actinides and the compensation by the use of moderating materials is discussed. (authors)

  8. On the use of moderating material to enhance the feedback coefficients in SFR cores with high minor actinide content

    Energy Technology Data Exchange (ETDEWEB)

    Merk, B. [Helmholtz-Zentrum Dresden-Rossendorf, Institut fuer Sicherheitsforschung, Postfach 51 01 19, 01314 Dresden (Germany); Weiss, F. P. [Gesellschaft fuer Anlagen- und Reaktorsicherheit GRS MbH Forschungszentrum, Boltzmannstr. 14, 85748 Garching (Germany)

    2012-07-01

    The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effecting sodium cooled fast reactor cores is described. The influence of the moderating material on the neutron spectrum, the power distribution, and the burnup distribution is shown. The consequences of the use of fine distributed moderating material into fuel assemblies with fuel configurations foreseen for minor actinide transmutation is analyzed and the transmutation efficiency is compared. The degradation of the feedback effects due to the insertion of minor actinides and the compensation by the use of moderating materials is discussed. (authors)

  9. Numerical simulation of turbulent Taylor-Couette flow between conducting cylinders in an axial magnetic field at low magnetic Reynolds number

    Science.gov (United States)

    Leng, Xueyuan; Kolesnikov, Yurii B.; Krasnov, Dmitry; Li, Benwen

    2018-01-01

    The effect of an axial homogeneous magnetic field on the turbulence in the Taylor-Couette flow confined between two infinitely long conducting cylinders is studied by the direct numerical simulation using a periodic boundary condition in the axial direction. The inner cylinder is rotating, and the outer one is fixed. We consider the case when the magnetic Reynolds number Rem ≪ 1, i.e., the influence of the induced magnetic field on the flow is negligible that is typical for industry and laboratory study of liquid metals. Relevance of the present study is based on the similarity of flow characteristics at moderate and high magnetic field for the cases with periodic and end-wall conditions at the large flow aspect ratio, as proven in the earlier studies. Two sets of Reynolds numbers 4000 and 8000 with several Hartmann numbers varying from 0 to 120 are employed. The results show that the mean radial induced electrical current, resulting from the interaction of axial magnetic field with the mean flow, leads to the transformation of the mean flow and the modification of the turbulent structure. The effect of turbulence suppression is dominating at a strong magnetic field, but before reaching the complete laminarization, we capture the appearance of the hairpin-like structures in the flow.

  10. High- and moderate-intensity aerobic exercise and excess post-exercise oxygen consumption in men with metabolic syndrome.

    Science.gov (United States)

    Larsen, I; Welde, B; Martins, C; Tjønna, A E

    2014-06-01

    Physical activity is central in prevention and treatment of metabolic syndrome. High-intensity aerobic exercise can induce larger energy expenditure per unit of time compared with moderate-intensity exercise. Furthermore, it may induce larger energy expenditure at post-exercise recovery. The aim of this study is to compare the excess post-exercise oxygen consumption (EPOC) in three different aerobic exercise sessions in men with metabolic syndrome. Seven men (age: 56.7 ± 10.8) with metabolic syndrome participated in this crossover study. The sessions consisted of one aerobic interval (1-AIT), four aerobic intervals (4-AIT), and 47-min continuous moderate exercise (CME) on separate days, with at least 48 h between each test day. Resting metabolic rate (RMR) was measured pre-exercise and used as baseline value. EPOC was measured until baseline metabolic rate was re-established. An increase in O2 uptake lasting for 70.4 ± 24.8 min (4-AIT), 35.9 ± 17.3 min (1-AIT), and 45.6 ± 17.3 min (CME) was observed. EPOC were 2.9 ± 1.7 L O2 (4-AIT), 1.3 ±  .1 L O2 (1-AIT), and 1.4 ± 1.1 L O2 (CME). There were significant differences (P exercise intensity has a significant positive effect on EPOC in men with metabolic syndrome. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Recent progress in the development of the Elliptic Blending Reynolds-stress model

    International Nuclear Information System (INIS)

    Manceau, Rémi

    2015-01-01

    Highlights: • Various modifications of the Elliptic Blending Reynolds stress model, proposed during the last decade, are revisited. • Using theoretical arguments and detailed comparison with DNS data, a reference model is formulated. • The model satisfactorily reproduces the effects of spanwise rotation on turbulence, for cases without and with separation. - Abstract: The Elliptic Blending Reynolds Stress Model (EB-RSM), originally proposed by Manceau and Hanjalić (2002) to extend standard, weakly inhomogeneous Reynolds stress models to the near-wall region, has been subject to various modifications by several authors during the last decade, mainly for numerical robustness reasons. The present work revisits all these modifications from the theoretical standpoint and investigates in detail their influence on the reproduction of the physical mechanisms at the origin of the influence of the wall on turbulence. The analysis exploits recent DNS databases for high-Reynolds number channel flows, spanwise rotating channel flows with strong rotation rates, up to complete laminarization, and the separated flow after a sudden expansion without and with system rotation. Theoretical arguments and comparison with DNS results lead to the selection of a recommended formulation for the EB-RSM model. This formulation shows satisfactory predictions for the configurations described above, in particular as regards the modification of the mean flow and turbulent anisotropy on the anticyclonic or pressure side

  12. Low Reynolds number suspension gravity currents.

    Science.gov (United States)

    Saha, Sandeep; Salin, Dominique; Talon, Laurent

    2013-08-01

    The extension of a gravity current in a lock-exchange problem, proceeds as square root of time in the viscous-buoyancy phase, where there is a balance between gravitational and viscous forces. In the presence of particles however, this scenario is drastically altered, because sedimentation reduces the motive gravitational force and introduces a finite distance and time at which the gravity current halts. We investigate the spreading of low Reynolds number suspension gravity currents using a novel approach based on the Lattice-Boltzmann (LB) method. The suspension is modeled as a continuous medium with a concentration-dependent viscosity. The settling of particles is simulated using a drift flux function approach that enables us to capture sudden discontinuities in particle concentration that travel as kinematic shock waves. Thereafter a numerical investigation of lock-exchange flows between pure fluids of unequal viscosity, reveals the existence of wall layers which reduce the spreading rate substantially compared to the lubrication theory prediction. In suspension gravity currents, we observe that the settling of particles leads to the formation of two additional fronts: a horizontal front near the top that descends vertically and a sediment layer at the bottom which aggrandises due to deposition of particles. Three phases are identified in the spreading process: the final corresponding to the mutual approach of the two horizontal fronts while the laterally advancing front halts indicating that the suspension current stops even before all the particles have settled. The first two regimes represent a constant and a decreasing spreading rate respectively. Finally we conduct experiments to substantiate the conclusions of our numerical and theoretical investigation.

  13. Magnetohydrodynamic duct and channel flows at finite magnetic Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Bandaru, Vinodh Kumar

    2015-11-27

    Lorentz force is found to show an R{sub m}{sup -1} dependence. After this, the phenomenon of dynamic runaway due to magnetic flux expulsion in a two-dimensional channel flow is studied. Comparison with an existing one-dimensional model shows a close agreement for the Hartmann regime and the bifurcation location but the model overpredicts the core velocities in the Poisuelle regime significantly. Parametric studies indicate the importance of the streamwise wavenumber of the imposed magnetic field on the bifurcation point. Finally, turbulent Hartmann duct flow is investigated at moderate values of R{sub m}. A higher R{sub m} is found to delay the onset of relaminarization to a higher value of Hartmann number. Large scale turbulence is induced at moderate R{sub m} and the effect increases with R{sub m}. Between the core and the Shercliff layers, Reynolds stresses decrease with increase in R{sub m}, leading to larger mean velocities in that region.

  14. Moderator/collimator for a proton/deuteron linac to produce a high-intensity, high-quality thermal neutron beam for neutron radiography

    International Nuclear Information System (INIS)

    Singleterry, R.C. Jr.; Imel, G.R.; McMichael, G.E.

    1995-01-01

    Reactor based high resolution neutron radiography facilities are able to deliver a well-collimated (L/D ≥100) thermal flux of 10 6 n/cm 2 ·sec to an image plane. This is well in excess of that achievable with the present accelerator based systems such as sealed tube D-T sources, Van der Graaff's, small cyclotrons, or low duty factor linacs. However, continuous wave linacs can accelerate tens of milliamperes of protons to 2.5 to 4 MeV. The MCNP code has been used to analyze target/moderator configurations that could be used with Argonne's Continuous Wave Linac (ACWL). These analyses have shown that ACWL could be modified to generate a neutron beam that has a high intensity and is of high quality

  15. Methane pellet moderator development

    International Nuclear Information System (INIS)

    Foster, C.A.; Schechter, D.E.; Carpenter, J.M.

    2004-01-01

    A methane pellet moderator assembly consisting of a pelletizer, a helium cooled sub-cooling tunnel, a liquid helium cooled cryogenic pellet storage hopper and a 1.5L moderator cell has been constructed for the purpose demonstrating a system for use in high-power spallation sources. (orig.)

  16. Cardiovascular Events in Cancer Patients Treated with Highly or Moderately Emetogenic Chemotherapy: Results from a Population-Based Study

    International Nuclear Information System (INIS)

    Vo, T. T.; Nelson, J. J.

    2012-01-01

    Studies on cardiovascular safety in cancer patients treated with highly or moderately emetogenic chemotherapy (HEC or MEC), who may have taken the antiemetic, aprepitant, have been limited to clinical trials and postmarketing spontaneous reports. Our study explored background rates of cardiovascular disease (CVD) events among HEC- or MEC-treated cancer patients in a population-based setting to contextualize events seen in a new drug development program and to determine at a high level whether rates differed by aprepitant usage. Medical and pharmacy claims data from the 2005-2007 IMPACT National Benchmark Database were classified into emetogenic chemotherapy categories and CVD outcomes. Among 5827 HEC/MEC-treated patients, frequencies were highest for hypertension (16-21%) and composites of venous (7-12%) and arterial thromboembolic events (4-7%). Aprepitant users generally did not experience higher frequencies of events compared to nonusers. Our study serves as a useful benchmark of background CVD event rates in a population-based setting of cancer patients.

  17. High altitude headache and acute mountain sickness at moderate elevations in a military population during battalion-level training exercises.

    Science.gov (United States)

    Norris, Jacob N; Viirre, Erik; Aralis, Hilary; Sracic, Michael K; Thomas, Darren; Gertsch, Jeffery H

    2012-08-01

    Few studies have evaluated high altitude headache (HAH) and acute mountain sickness (AMS) in military populations training at moderate (1,500-2,500 m) to high altitudes (>2,500 m). In the current study, researchers interviewed active duty personnel training at Marine Corps Mountain Warfare Training Center. Participants were asked about HAH and AMS symptoms, potential risk factors, and medications used. In a sample of 192 U.S. Navy and Marine Corps personnel, 14.6% reported AMS (Lake Louise Criteria > or = 3) and 28.6% reported HAH. Dehydration and recent arrival at altitude (defined as data collected on days 2-3) were significantly associated with AMS; decreased sleep allowance was significantly associated with HAH. Although ibuprofen/Motrin users were more likely to screen positive for AMS, among AMS-positive participants, ibuprofen/Motrin users had decreased likelihood of reporting robust AMS relative to non-ibuprofen/Motrin users (p altitude. Further, ibuprofen/Motrin may be a reasonable treatment for the symptoms of AMS and HAH, although further study is warranted.

  18. Comparison of Low-, Moderate-, and High-Molecular-Weight Hyaluronic Acid Injections in Delaying Time to Knee Surgery.

    Science.gov (United States)

    Shewale, Anand R; Barnes, Charles L; Fischbach, Lori A; Ounpraseuth, Songthip T; Painter, Jacob T; Martin, Bradley C

    2017-10-01

    We compared the effectiveness of low-molecular-weight (MW) hyaluronic acid (HA) injections (LMWHA), moderate-MW HA injections (MMWHA), and high-MW HA injections (HMWHA) for prevention or delay of knee surgery in patients with knee osteoarthritis. An observational cohort study using LifeLink Plus claims (2006-2015) was used. The primary outcome measure of the study included all surgical interventions of the knee. The secondary outcome measures were the following: (1) unicompartmental knee arthroplasty or total knee arthroplasty and (2) total knee arthroplasty only. A high-dimensional propensity score (hdPS) using 1:1 matching was used to adjust for confounding. The likelihood of each outcome was assessed using Cox proportional hazard models. A cohort of 30,417 incident HA users with knee osteoarthritis met our inclusion-exclusion criteria. There was no difference in the likelihood of composite surgical events between LMWHA users (hazard ratio, 0.939; 95% confidence interval, 0.870-1.013) and MMWHA users (hazard ratio, 1.032; 95% confidence interval, 0.952-1.119) when compared with HMWHA users in a matched hdPS analysis. However, a significantly lower likelihood for all outcome measures was demonstrated in LMWHA and MMWHA users compared with HMWHA users when hdPS was not used. There was no significant difference in the likelihood of surgical interventions between LMWHA, MMWHA, and HMWHA users after accounting for empirically derived confounders. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Feasibility of using microbiology diagnostic tests of moderate or high complexity at the point - of - care in a delivery suite.

    Science.gov (United States)

    Gray, J W; Milner, P J; Edwards, E H; Daniels, J P; Khan, K S

    2012-07-01

    Point-of-care testing (POCT) is one of the fastest growing sectors of laboratory diagnostics. Most tests in routine use are haematology or biochemistry tests that are of low complexity. Microbiology POCT has been constrained by a lack of tests that are both accurate and of low complexity. We describe our experience of the practical issues around using more complex POCT for detection of Group B streptococci (GBS) in swabs from labouring women. We evaluated two tests for their feasibility in POCT: an optical immune assay (Biostar OIA Strep B, Inverness Medical, Princetown, NJ) and a PCR (IDI-Strep B, Cepheid, Sunnyvale, CA), which have been categorised as being of moderate and high complexity, respectively. A total of 12 unqualified midwifery assistants (MA) were trained to undertake testing on the delivery suite. A systematic approach to the introduction and management of POC testing was used. Modelling showed that the probability of test results being available within a clinically useful timescale was high. However, in the clinical setting, we found it impossible to maintain reliable availability of trained testers. Implementation of more complex POC testing is technically feasible, but it is expensive, and may be difficult to achieve in a busy delivery suite.

  20. Validity of the modified Reynolds equation for incompressible active lubrication

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Santos, Ilmar

    2016-01-01

    The modified Reynolds equation for active lubrication has been the cornerstone around which the theoretical investigations regarding actively lubricated bearings have evolved over the years. Introduced originally in 1994, it enables to calculate in a simplified manner the bearing pressure field...... as a function of servovalve controlled pressurized oil injection. This article deals with a preliminary critical review of the simplificatory assumptions that are introduced into the modified Reynolds equation in order to model the phenomena taking place in the interface between the injection nozzle...... and the bearing clearance. The analysis is performed by means of direct comparison of the results of the modified Reynolds equation model versus benchmark CFD calculations, applied to a geometry representative of the system analyzed. The results show that the modified Reynolds equation mathematical simplicity...

  1. Management of Stroke Prevention in Canadian Patients with Atrial Fibrillation at Moderate to High Risk of Stroke

    Science.gov (United States)

    Semchuk, William M; Levac, Brandon; Lara, Muria; Shakespeare, Annabelle; Evers, Thomas; Bolt, Jennifer

    2013-01-01

    Background Many patients with atrial fibrillation who are at moderate to high risk of stroke do not receive anticoagulation with vitamin K antagonists (VKAs) in accordance with recommendations. Objective: To determine (1) why Canadian patients with atrial fibrillation who are potentially eligible for VKA do not receive this therapy, (2) why Canadian primary care physicians discontinue VKA therapy, and (3) why VKA therapy is perceived as difficult to manage. Methods: The study involved a chart review of 3 cohorts of patients with nonvalvular atrial fibrillation at moderate to high risk of stroke: patients who had never received VKA treatment (VKA-naive), those whose treatment had been discontinued, and those whose VKA treatment was considered difficult to manage. Results: Charts for 187 patients (mean age 78.4 years, standard deviation 8.9 years) treated at 39 primary care sites were reviewed (62 treatment-naive, 42 with therapy discontinued, and 83 whose therapy was considered difficult to manage). Atrial fibrillation was paroxysmal in 82 (44%) of the patients, persistent in 47 patients (25%), and permanent in 58 (31%). One patient in each of the 3 cohorts had experienced a stroke during the 6 months before study participation. Bleeding events were more frequent among patients who had discontinued VKA therapy than in the other 2 groups. Among those whose therapy was discontinued and those whose therapy was difficult to manage, the mean time in the therapeutic range was 46.3% and 56.4%, respectively. The most common reason for not initiating VKA therapy in treatment-naive patients was the transient nature of atrial fibrillation (25/62 [40%]). The most common reason for discontinuation of VKA therapy was a bleeding event (10/42 [24%]). The presence of a concomitant chronic disease was the most common reason that a patient’s therapy was considered difficult to manage (46/83 [55%]). Conclusions: VKA therapy was not initiated or was discontinued for various reasons

  2. Management of stroke prevention in canadian patients with atrial fibrillation at moderate to high risk of stroke.

    Science.gov (United States)

    Semchuk, William M; Levac, Brandon; Lara, Muria; Shakespeare, Annabelle; Evers, Thomas; Bolt, Jennifer

    2013-09-01

    Many patients with atrial fibrillation who are at moderate to high risk of stroke do not receive anticoagulation with vitamin K antagonists (VKAs) in accordance with recommendations. To determine (1) why Canadian patients with atrial fibrillation who are potentially eligible for VKA do not receive this therapy, (2) why Canadian primary care physicians discontinue VKA therapy, and (3) why VKA therapy is perceived as difficult to manage. The study involved a chart review of 3 cohorts of patients with nonvalvular atrial fibrillation at moderate to high risk of stroke: patients who had never received VKA treatment (VKA-naive), those whose treatment had been discontinued, and those whose VKA treatment was considered difficult to manage. Charts for 187 patients (mean age 78.4 years, standard deviation 8.9 years) treated at 39 primary care sites were reviewed (62 treatment-naive, 42 with therapy discontinued, and 83 whose therapy was considered difficult to manage). Atrial fibrillation was paroxysmal in 82 (44%) of the patients, persistent in 47 patients (25%), and permanent in 58 (31%). One patient in each of the 3 cohorts had experienced a stroke during the 6 months before study participation. Bleeding events were more frequent among patients who had discontinued VKA therapy than in the other 2 groups. Among those whose therapy was discontinued and those whose therapy was difficult to manage, the mean time in the therapeutic range was 46.3% and 56.4%, respectively. The most common reason for not initiating VKA therapy in treatment-naive patients was the transient nature of atrial fibrillation (25/62 [40%]). The most common reason for discontinuation of VKA therapy was a bleeding event (10/42 [24%]). The presence of a concomitant chronic disease was the most common reason that a patient's therapy was considered difficult to manage (46/83 [55%]). VKA therapy was not initiated or was discontinued for various reasons. Multiple comorbid conditions made management of VKA

  3. Determination of NABE in urine of high-yield dairy cows in early lactation in conditions of moderate heat stress

    Directory of Open Access Journals (Sweden)

    Fratrić Natalija

    2010-01-01

    Full Text Available The work presents the results of investigations of the effect of moderate heat stress on the acidobasal status in high-yield dairy cows in early lactation. Improving performance in high-yield dairy cows increases their inclination toward metabolic disorders. The most likely to be affected is the acid-base balance, in particular when cows are exposed to heat stress. Investigations so far have shown that the taking of urine samples and their analysis is the best and fastest way to diagnose disorders in the acid-base balance. Investigations were carried out on 7 clinically healthy cows of the Holstein- Friesian breed in the phase of early lactation, 30 to 40 days (on days 30, 33 and 40 following calving during the summer period, during the month of July, when there were significant variations in daily and nightly temperatures. The cows were in the second and fourth lactation, the annual milk yield was 8000 L milk per cow. The average daily milk production in the early phase of lactation ranged from 35 to 40 L. The cows were fed mixed rations (TMR twice daily. Lucerne hay in limited quantities was given to the cows prior to the mixed feed ration. The ration for this animal category was optimized on the grounds of the daily milk production. The balance of cations and anions in the feed ration stood at 95 mEq/kg DM. The results clearly demonstrate the cows' response to moderate heat stress through the defense parameters in urine (urine pH, NABE (net-acid-base-excretion, acids, bases, ammonium ion (NH4. The determination of the kidney NABE yields more correct data than the urine pH on acidotic conditions. The results of examinations of the urine pH do not show any digressions from physiological values and are approximately the same in all cows during the investigated periods. Normal NABE values are from 100-200 mmol/L. Burdening with acid products results in a NABE range from 0-100mmol/L, and metabolic acidosis results in NAB<0 mmol/L. NABE in the cows

  4. Kate Watson on Reynold Humphries’ Hollywood’s Blacklists

    Directory of Open Access Journals (Sweden)

    2008-12-01

    Full Text Available Reynold Humphries. Hollywood’s Blacklists: A Political and Cultural History. Edinburgh: Edinburgh University Press, 2008. Reynold Humphries’ Hollywood’s Blacklists provides a comprehensive examination of the historical and political ramifications of the blacklisting process and of Communism in the motion picture industry. His section on ‘The Background’ initially sets up just this, making the debate and dispute accessible even to those not au fait with such knowledge. This section is informat...

  5. Vertical Distribution of Tidal Flow Reynolds Stress in Shallow Sea

    Institute of Scientific and Technical Information of China (English)

    SONG Zhi-yao; NI Zhi-hui; LU Guo-nian

    2009-01-01

    Based on the results of the tidal flow Reynolds stresses of the field observations,indoor experiments,and numerical models,the parabolic distribution of the tidal flow Reynolds stress is proposed and its coefficients are determined theoretically in this paper.Having been well verified with the field data and experimental data,the proposed distribution of Reynolds stress is also compared with numerical model results,and a good agreement is obtained,showing that this distribution can well reflect the basic features of Reynolds stress deviating from the linear distribution that is downward when the tidal flow is of acceleration,upward when the tidal flow is of deceleration.Its dynamics cause is also discussed preliminarily and the influence of the water depth is pointed out from the definition of Reynolds stress,turbulent generation,transmission,and so on.The established expression for the vertical distribution of the tidal flow Reynolds stress is not only simple and explicit,but can also well reflect the features of the tidal flow acceleration and deceleration for further study on the velocity profile of tidal flow.

  6. Reynolds stress scaling in pipe flow turbulence-first results from CICLoPE.

    Science.gov (United States)

    Örlü, R; Fiorini, T; Segalini, A; Bellani, G; Talamelli, A; Alfredsson, P H

    2017-03-13

    This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×10 4 are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend-Perry constant of A 2 ≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend-Perry constant, i.e. A 2,w ≈A 2 /2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

  7. Shear flow generation by Reynolds stress and suppression of resistive g-modes

    International Nuclear Information System (INIS)

    Sugama, H.; Horton, W.

    1993-08-01

    Suppression of resistive g-mode turbulence by background shear flow generated from a small external flow source and amplified by the fluctuation-induced Reynolds stress is demonstrated and analyzed. The model leads to a paradigm for the low-to-high (L-H) confinement mode transition. To demonstrate the L-H transition model, single-helicity nonlinear fluid simulations using the vorticity equation for the electrostatic potential, the pressure fluctuation equation and the background poloidal flow equation are used in the sheared slab configuration. The relative efficiency of the external flow and the Reynolds stress for producing shear flow depends on the poloidal flow damping parameter ν which is given by neoclassical theory. For large ν, the external flow is a dominant contribution to the total background poloidal shear flow and its strength predicted by the neoclassical theory is not enough to suppress the turbulence significantly. In contrast, for small ν, we show that the fluctuations drive a Reynolds stress that becomes large and suddenly, at some critical point in time, shear flow much larger than the external flow is generated and leads to an abrupt, order unity reduction of the turbulent transport just like that of the L-H transition in tokamak experiments. It is also found that, even in the case of no external flow, the shear flow generation due to the Reynolds stress occurs through the nonlinear interaction of the resistive g-modes and reduces the transport. To supplement the numerical solutions we derive the Landau equation for the mode amplitude of the resistive g-mode taking into account the fluctuation-induced shear flow and analyze the opposite action of the Reynolds stress in the resistive g turbulence compared with the classical shear flow Kelvin-Helmholtz (K-H) driven turbulence

  8. Moderator for nuclear reactor

    International Nuclear Information System (INIS)

    Milgram, M.S.; Dunn, J.T.; Hart, R.S.

    1995-01-01

    This invention relates to a moderator for a nuclear reactor and more specifically, to a composite moderator. A moderator is designed to slow down, or thermalize, neutrons which are released during nuclear reactions in the reactor fuel. Pure or almost pure materials like light water, heavy water, beryllium or graphite are used singly as moderators at present. All these materials, are used widely. Graphite has a good mechanical strength at high temperatures encountered in the nuclear core and therefore is used as both the moderator and core structural material. It also exhibits a low neutron-capture cross section and high neutron scattering cross section. However, graphite is susceptible to attach by carbon dioxide and/or oxygen where applicable, and releases stress energy under certain circumstances, although under normal operating conditions these reactions can be controlled. (author). 1 tab

  9. Taphonomic expressions of sedimentary hiatuses: field observations on bioclastic concentrations and sequence anatomy in low, moderate and high subsidence settings

    Science.gov (United States)

    Kidwell, S. M.

    1993-07-01

    Field studies of post-Palaeozoic siliciclastic records reveal a strong concordance between different types of bioclastic concentrations and discontinuity surfaces within third-order sequences (≈ 1 My duration), supporting the use of taphonomic criteria in establishing the relative magnitudes of sedimentary hiatuses. Comparison of records across a spectrum of subsidence rates, however (from ≤ 10 m to > 1 km/My), shows that, along with appreciable changes in sequence anatomy, the nature of surface-mantling bioclastic concentrations also changes. The most significant surfaces (second- and third-order sequence boundaries, surfaces or intervals of maximum transgression, transgressive surfaces) tend to be either bare or mantled with taphonomically complex hiatal and lag concentrations. These were more consistently encountered in low subsidence than in moderate subsidence records. In high subsidence records, major surfaces were more often mantled by composite or event concentrations, if they were bioclastic at all. In all subsidence settings, comparatively minor surfaces (parasequence boundaries, bed set boundaries and bedding planes) were bare or mantled with relatively simple event and composite concentrations. Although all fossil assemblages are biased taphonomically to some degree, relative degrees of bias should almost certainly vary among discontinuities as a general rule, suggesting specific adjustments in sampling strategies for evolutionary studies.

  10. Effect of high-intensity training versus moderate training on peak oxygen uptake and chronotropic response in heart transplant recipients

    DEFF Research Database (Denmark)

    Dall, C H; Snoer, M; Christensen, S

    2014-01-01

    In heart transplant (HTx) recipients, there has been reluctance to recommend high-intensity interval training (HIIT) due to denervation and chronotropic impairment of the heart. We compared the effects of 12 weeks' HIIT versus continued moderate exercise (CON) on exercise capacity and chronotropic...... response in stable HTx recipients >12 months after transplantation in a randomized crossover trial. The study was completed by 16 HTx recipients (mean age 52 years, 75% males). Baseline peak oxygen uptake (VO2peak ) was 22.9 mL/kg/min. HIIT increased VO2peak by 4.9 ± 2.7 mL/min/kg (17%) and CON by 2.6 ± 2.......2 mL/kg/min (10%) (significantly higher in HIIT; p HIIT, systolic blood pressure decreased significantly (p = 0.037) with no significant change in CON (p = 0.241; between group difference p = 0.027). Peak heart rate (HRpeak ) increased significantly by 4.3 beats per minute (p = 0...

  11. High-Intensity Interval Training Versus Moderate-Intensity Continuous Training in the Prevention/Management of Cardiovascular Disease.

    Science.gov (United States)

    Hussain, Syed R; Macaluso, Andrea; Pearson, Stephen J

    Moderate-intensity continuous training (MICT) has long been considered the most effective exercise treatment modality for the prevention and management of cardiovascular disease (CVD), but more recently high-intensity interval training (HIIT) has been viewed as a potential alternative to MICT in accruing such benefits. HIIT was initially found to induce significant improvements in numerous physiological and health-related indices, to a similar if not superior extent to MICT. Since then, many studies have attempted to explore the potential clinical utility of HIIT, relative to MICT, with respect to treating numerous cardiovascular conditions, such as coronary artery disease, heart failure, stroke, and hypertension. Despite this, however, the efficacy of HIIT in reversing the specific symptoms and risk factors of these cardiovascular pathologies is not well understood. HIIT is often perceived as very strenuous, which could render it unsafe for those at risk of or afflicted with CVD, but these issues are also yet to be reviewed. Furthermore, the optimal HIIT protocol for each of the CVD cohorts has not been established. Thus, the purpose of this review article is to (1) evaluate the efficacy of HIIT relative to MICT in the prevention and management of cardiovascular conditions, and (2) explore any potential safety issues surrounding the suitability and/or tolerability of HIIT for patients with CVD, and the potential optimal prescriptive variables of HIIT for application in the clinical environment.

  12. Performance Characteristics of the Reverse Syphilis Screening Algorithm in a Population With a Moderately High Prevalence of Syphilis.

    Science.gov (United States)

    Rourk, Angela R; Nolte, Frederick S; Litwin, Christine M

    2016-11-01

    With the recent introduction of automated treponemal tests, a new reverse syphilis algorithm has been proposed and now used by many clinical laboratories. We analyzed the impact of instituting the reverse screening syphilis algorithm in a laboratory that serves a geographic area with a moderately high prevalence of syphilis infection. Serum samples sent for syphilis testing were tested using a treponemal enzyme immunoassay (EIA) as the screening assay. EIA reactive samples were tested by rapid plasma reagin (RPR) and titered to end point if reactive. RPR nonreactive samples were analyzed by the Treponema pallidum particle agglutination test (TP-PA). Pertinent medical records were reviewed for false-reactive screens and samples with evidence of past syphilis infection. Among 10,060 patients tested, 502 (5%) were reactive on the initial EIA screen. The RPR was reactive in 150 (1.5%). TP-PA testing determined that 103 (1.0%) were falsely reactive on initial EIA screen. The reverse screening algorithm, however, identified 242 (2.4%) with evidence of latent, secondary, or past syphilis, 21 of whom had no or unknown prior treatment with antibiotics. Despite a 1.0% false-reactive rate, the reverse syphilis algorithm detected 21 patients with possible latent syphilis that may have gone undetected by traditional syphilis screening. © American Society for Clinical Pathology, 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

  13. Effect of 24 sessions of high-intensity aerobic interval training carried out at either high or moderate frequency, a randomized trial.

    Science.gov (United States)

    Hatle, Håvard; Støbakk, Per Kristian; Mølmen, Harald Edvard; Brønstad, Eivind; Tjønna, Arnt Erik; Steinshamn, Sigurd; Skogvoll, Eirik; Wisløff, Ulrik; Ingul, Charlotte Björk; Rognmo, Øivind

    2014-01-01

    The training response of an intensified period of high-intensity exercise is not clear. Therefore, we compared the cardiovascular adaptations of completing 24 high-intensity aerobic interval training sessions carried out for either three or eight weeks, respectively. Twenty-one healthy subjects (23.0±2.1 years, 10 females) completed 24 high-intensity training sessions throughout a time-period of either eight weeks (moderate frequency, MF) or three weeks (high frequency, HF) followed by a detraining period of nine weeks without any training. In both groups, maximal oxygen uptake (VO2max) was evaluated before training, at the 9(th) and 17(th) session and four days after the final 24(th) training session. In the detraining phase VO2max was evaluated after 12 days and thereafter every second week for eight weeks. Left ventricular echocardiography, carbon monoxide lung diffusion transfer factor, brachial artery flow mediated dilatation and vastus lateralis citrate maximal synthase activity was tested before and after training. The cardiovascular adaptation after HF training was delayed compared to training with MF. Four days after ending training the HF group showed no improvement (+3.0%, p = 0.126), whereas the MF group reached their highest VO2max with a 10.7% improvement (ptraining of high-intensity aerobic exercise improves VO2max. The cardiovascular adaptation following a HF programme of high-intensity exercise is however delayed compared to MF training. ClinicalTrials.gov NCT00733941.

  14. CHILD SEXUAL ABUSE, BULLYING, CYBERBULLYING, AND MENTAL HEALTH PROBLEMS AMONG HIGH SCHOOLS STUDENTS: A MODERATED MEDIATED MODEL.

    Science.gov (United States)

    Hébert, Martine; Cénat, Jude Mary; Blais, Martin; Lavoie, Francine; Guerrier, Mireille

    2016-07-01

    Child sexual abuse is associated with adverse outcomes, including heightened vulnerability that may translate into risk of revictimization. The aims of the study were: (1) to explore the direct and indirect links between child sexual abuse and cyberbullying, bullying, and mental health problems and (2) to study maternal support as a potential protective factor. Teenagers involved in the two first waves of the Quebec Youths' Romantic Relationships Survey (N = 8,194 and 6,780 at Wave I and II, respectively) completed measures assessing child sexual abuse and maternal support at Wave I. Cyberbullying, bullying, and mental health problems (self-esteem, psychological distress, and suicidal ideations) were evaluated 6 months later. Rates of cyberbullying in the past 6 months were twice as high in sexually abused teens compared to nonvictims both for girls (33.47 vs. 17.75%) and boys (29.62 vs. 13.29%). A moderated mediated model revealed a partial mediation effect of cyberbullying and bullying in the link between child sexual abuse and mental health. Maternal support acted as a protective factor as the conditional indirect effects of child sexual abuse on mental health via cyberbullying and bullying were reduced in cases of high maternal support. Results have significant relevance for prevention and intervention in highlighting the heightened vulnerability of victims of child sexual abuse to experience both bullying and cyberbullying. Maternal support may buffer the risk of developing mental health distress, suggesting that intervention programs for victimized youth may profit by fostering parent involvement. © 2016 Wiley Periodicals, Inc.

  15. Neutronic performance of high-density LEU fuels in water-moderated and water-reflected research reactors

    International Nuclear Information System (INIS)

    Bretscher, M.M.; Matos, J.E.

    1996-01-01

    At the Reduced Enrichment for Research and Test Reactors (RERTR) meeting in September 1994, Durand reported that the maximum uranium loading attainable with U 3 Si 2 fuel is about 6.0 g U/cm 3 . The French Commissariat a l'Energie Atomique (CEA) plan to perform irradiation tests with 5 plates at this loading. Compagnie pour L'Etude et La Realisation de Combustibles Atomiques (CERCA) has also fabricated a few uranium nitride (UN) plates with a uranium density in the fuel meat of 7.0 g/cm 3 and found that UN is compatible with the aluminum matrix at temperatures below 500 C. High density dispersion fuels proposed for development include U-Zr(4 wt%)-Nb(2 wt%), U-Mo(5 wt%), and U-Mo(9 wt%). The purpose of this note is to examine the relative neutronic behavior of these high density fuels in a typical light water-reflected and water-moderated MTR-type research reactor. The results show that a dispersion of the U-Zr-Nb alloy has the most favorable neutronic properties and offers the potential for uranium densities greater than 8.0 g/cm 3 . On the other hand, UN is the least reactive fuel because of the relatively large 14 N(n,p) cross section. For a fixed value of k eff , the required 235 U loading per fuel element is least for the U-Zr-Nb fuel and steadily increases for the U-Mo(5%), U-Mo(9%), and UN fuels. Because of volume fraction limitations, the UO 2 dispersions are only useful for uranium densities below 5.0 g/cm 3 . In this density range, however, UO 2 is more reactive than U 3 Si 2

  16. Greater effects of high- compared with moderate-intensity interval training on cardio-metabolic variables, blood leptin concentration and ratings of perceived exertion in obese adolescent females

    OpenAIRE

    Racil, G; Coquart, JB; Elmontassar, W; Haddad, M; Goebel, R; Chaouachi, A; Amri, M; Chamari, K

    2016-01-01

    This study examined the effects of high- vs. moderate-intensity interval training on cardiovascular fitness, leptin levels and ratings of perceived exertion (RPE) in obese female adolescents. Forty-seven participants were randomly assigned to one of three groups receiving either a 1:1 ratio of 15 s of effort comprising moderate-intensity interval training (MIIT at 80% maximal aerobic speed: MAS) or high-intensity interval training (HIIT at 100% MAS), with matched 15 s recovery at 50% MAS, thr...

  17. Simulations of three-dimensional viscoelastic flows past a circular cylinder at moderate Reynolds numbers

    KAUST Repository

    RICHTER, DAVID; IACCARINO, GIANLUCA; SHAQFEH, ERIC S. G.

    2010-01-01

    The results from a numerical investigation of inertial viscoelastic flow past a circular cylinder are presented which illustrate the significant effect that dilute concentrations of polymer additives have on complex flows. In particular, effects

  18. Effect of a high bicarbonate mineral water on fasting and postprandial lipemia in moderately hypercholesterolemic subjects: a pilot study.

    Science.gov (United States)

    Zair, Yassine; Kasbi-Chadli, Fatima; Housez, Beatrice; Pichelin, Mathieu; Cazaubiel, Murielle; Raoux, François; Ouguerram, Khadija

    2013-07-18

    During postprandial state, TG concentration is increasing and HDL cholesterol decreasing, leading to a transitory pro-atherosclerotic profile. Previous studies have reported that bicarbonate water improve postprandial lipemia. The objective of this study was to analyze the effect of a strongly bicarbonated mineral water on lipoprotein levels during fasting and postprandial state. A controlled, randomised, double-blind cross-over design was conducted in 12 moderately hypercholesterolemic subjects after a daily ingestion of 1.25 L of mineral (SY) or low mineral water during eight weeks separated by a one week wash-out period. Blood samples were collected in first visit to the hospital (V1) before water consumption (referent or SY) and in a second visit (V2) after eight week water consumption period. The effect of the consumed water was studied in fasting and in postprandial state during ingestion of a meal and 0.5 L of water. Comparison of data between V1 and V2 after SY consumption showed a significant decrease in triglyceridemia (23%), VLDL TG (31%) and tendency to a decrease of VLDL cholesterol (p = 0.066) at fasting state. Whatever the consumed water during postprandial state, the measurement of total areas under curves did not show a significant difference. No difference was observed between SY and referent water consumption for measured parameters at fasting and postprandial state. When subjects consumed SY we showed a decrease of their basal TG and VLDLTG. The unexpected absence of effect of high mineralized water on postprandial lipemia, probably related to experimental conditions, is discussed in the discussion section.

  19. High-Intensity Interval Training as an Efficacious Alternative to Moderate-Intensity Continuous Training for Adults with Prediabetes

    Directory of Open Access Journals (Sweden)

    Mary E. Jung

    2015-01-01

    Full Text Available Aims. High-intensity interval training (HIIT leads to improvements in various markers of cardiometabolic health but adherence to HIIT following a supervised laboratory intervention has yet to be tested. We compared self-report and objective measures of physical activity after one month of independent exercise in individuals with prediabetes who were randomized to HIIT (n=15 or traditional moderate-intensity continuous training (MICT, n=17. Method. After completing 10 sessions of supervised training participants were asked to perform HIIT or MICT three times per week for four weeks. Results. Individuals in HIIT (89 ± 11% adhered to their prescribed protocol to a greater extent than individuals in MICT (71 ± 31% as determined by training logs completed over one-month follow-up (P = 0.05, Cohen’s d = 0.75. Minutes spent in vigorous physical activity per week measured by accelerometer were higher in HIIT (24 ± 18 as compared to MICT (11 ± 10 at one-month follow-up (P = 0.049, Cohen’s d = 0.92. Cardiorespiratory fitness and systolic blood pressure assessed at one-month follow-up were equally improved (P’s < 0.05. Conclusions. This study provides preliminary evidence that individuals with prediabetes can adhere to HIIT over the short-term and do so at a level that is greater than MICT.

  20. Mechanical efficiency of high versus moderate intensity aerobic exercise in coronary heart disease patients: A randomized clinical trial.

    Science.gov (United States)

    Villelabeitia-Jaureguizar, Koldobika; Vicente-Campos, Davinia; Berenguel Senen, Alejandro; Verónica Hernández Jiménez, Verónica; Lorena Ruiz Bautista, Lorena; Barrios Garrido-Lestache, María Elvira; López Chicharro, Jose

    2018-05-10

    Mechanical efficiency (ME) refers to the ability of an individual to transfer energy consumed by external work. A decreased ME, could represent an increased energy cost during exercise and may, therefore, be limited in terms of physical activity. This study aimed to compare the influence of two different exercise protocols: moderate continuous training (MCT) versus high intensity interval training (HIIT), as part of a cardiac rehabilitation program on ME values among coronary patients. 110 coronary patients were assigned to either HIIT or MCT groups for 8 weeks. Incremental exercise tests in a cycle ergometer were performed to obtain VO₂peak. Net energy expenditure (EE) and ME were obtained at intensities corresponding to the first (VT₁) and second (VT₂) ventilatory thresholds, and at VO₂peak. Both exercise programs significantly increase VO₂peak with a higher increase in the HIIT group (2.96 ± 2.33 mL/kg/min vs. 3.88 ± 2.40 mL/kg/min, for patients of the MCT and HIIT groups respectively, p HIIT group. At VT₁, ME significantly increased in both groups, with a greater increase in the HIIT group (2.20 ± 6.25% vs. 5.52 ± 5.53%, for patients of the MCT and HIIT groups respectively, p HIIT to patients with chronic ischemic heart disease of low risk resulted in a greater improvement in VO₂peak and in ME at VT₁, than when MCT was applied. Moreover, only the application of HIIT brought about a significant increase in ME at VT₂ and at VO₂peak.

  1. Three-scale expansion of the solution of MHD and Reynolds equations for tokamak

    International Nuclear Information System (INIS)

    Maslov, V.P.; Omel'yanov, G.A.

    1994-01-01

    An asymptotic solution of the magnetohydrodynamic equations is constructed. The three scales asymptotic solution describes the non-linear evolution of small, rapidly varying perturbations of equilibrium. It is shown, that an anisotropic coherent structure appears in the linear nonstability situation, and the structures evolution directs to energy interaction between high-frequency and low-frequency waves. The closed system of MHD Reynolds equations for anisotropic structure is derived

  2. Flow control at low Reynolds numbers using periodic airfoil morphing

    Science.gov (United States)

    Jones, Gareth; Santer, Matthew; Papadakis, George; Bouremel, Yann; Debiasi, Marco; Imperial-NUS Joint PhD Collaboration

    2014-11-01

    The performance of airfoils operating at low Reynolds numbers is known to suffer from flow separation even at low angles of attack as a result of their boundary layers remaining laminar. The lack of mixing---a characteristic of turbulent boundary layers---leaves laminar boundary layers with insufficient energy to overcome the adverse pressure gradient that occurs in the pressure recovery region. This study looks at periodic surface morphing as an active flow control technique for airfoils in such a flight regime. It was discovered that at sufficiently high frequencies an oscillating surface is capable of not only reducing the size of the separated region---and consequently significantly reducing drag whilst simultaneously increasing lift---but it is also capable of delaying stall and as a result increasing CLmax. Furthermore, by bonding Macro Fiber Composite actuators (MFCs) to the underside of an airfoil skin and driving them with a sinusoidal frequency, it is shown that this control technique can be practically implemented in a lightweight, energy efficient way. Imperial-NUS Joint Ph.D. Programme.

  3. Experimental Investigation of Reynolds Number Effects on Test Quality in a Hypersonic Expansion Tube

    Science.gov (United States)

    Rossmann, Tobias; Devin, Alyssa; Shi, Wen; Verhoog, Charles

    2017-11-01

    Reynolds number effects on test time and the temporal and spatial flow quality in a hypersonic expansion tube are explored using high-speed pressure, infrared optical, and Schlieren imaging measurements. Boundary layer models for shock tube flows are fairly well established to assist in the determination of test time and flow dimensions at typical high enthalpy test conditions. However, the application of these models needs to be more fully explored due to the unsteady expansion of turbulent boundary layers and contact regions separating dissimilar gasses present in expansion tube flows. Additionally, expansion tubes rely on the development of a steady jet with a large enough core-flow region at the exit of the acceleration tube to create a constant velocity region inside of the test section. High-speed measurements of pressure and Mach number at several locations within the expansion tube allow for the determination of an experimental x-t diagram. The comparison of the experimentally determined x-t diagram to theoretical highlights the Reynolds number dependent effects on expansion tube. Additionally, spatially resolved measurements of the Reynolds number dependent, steady core-flow in the expansion tube viewing section are shown. NSF MRI CBET #1531475, Lafayette College, McCutcheon Foundation.

  4. Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure.

    Science.gov (United States)

    Cordioli, Ricardo Luiz; Park, Marcelo; Costa, Eduardo Leite Vieira; Gomes, Susimeire; Brochard, Laurent; Amato, Marcelo Britto Passos; Azevedo, Luciano Cesar Pontes

    2014-12-01

    The aim of this study was to explore if positive-pressure ventilation delivered by a conventional ICU ventilator at a moderately high frequency (HFPPV) allows a safe reduction of tidal volume (V T) below 6 mL/kg in a porcine model of severe acute respiratory distress syndrome (ARDS) and at a lower mean airway pressure than high-frequency oscillatory ventilation (HFOV). This is a prospective study. In eight pigs (median weight 34 [29,36] kg), ARDS was induced by pulmonary lavage and injurious ventilation. The animals were ventilated with a randomized sequence of respiratory rates: 30, 60, 90, 120, 150, followed by HFOV at 5 Hz. At each step, V T was adjusted to allow partial pressure of arterial carbon dioxide (PaCO2) to stabilize between 57 and 63 mmHg. Data are shown as median [P25th,P75th]. After lung injury, the PaO2/FiO2 (P/F) ratio was 92 [63,118] mmHg, pulmonary shunt 26 [17,31]%, and static compliance 11 [8,14] mL/cmH2O. Positive end-expiratory pressure (PEEP) was 14 [10,17] cmH2O. At 30 breaths/min, V T was higher than 6 (7.5 [6.8,10.2]) mL/kg, but at all higher frequencies, V T could be reduced and PaCO2 maintained, leading to reductions in plateau pressures and driving pressures. For frequencies of 60 to 150/min, V T progressively fell from 5.2 [5.1,5.9] to 3.8 [3.7,4.2] mL/kg (p mechanics, auto-PEEP generation, hemodynamics, or gas exchange. Mean airway pressure was maintained constant and was increased only during HFOV. During protective mechanical ventilation, HFPPV delivered by a conventional ventilator in a severe ARDS swine model safely allows further tidal volume reductions. This strategy also allowed decreasing airway pressures while maintaining stable PaCO2 levels.

  5. Prevalence of atherogenic dyslipidemia in primary care patients at moderate-very high risk of cardiovascular disease. Cardiovascular risk perception.

    Science.gov (United States)

    Plana, Nuria; Ibarretxe, Daiana; Cabré, Anna; Ruiz, Emilio; Masana, Lluis

    2014-01-01

    Atherogenic dyslipidemia is an important risk factor for cardiovascular disease. We aim to determine atherogenic dyslipidemia prevalence in primary care patients at moderate-very high cardiovascular risk and its associated cardiovascular risk perception in Spain. This cross-sectional study included 1137 primary care patients. Patients had previous cardiovascular disease, diabetes mellitus, SCORE risk ≥ 3, severe hypertension or dyslipidemia. Atherogenic dyslipidemia was defined as low HDL-C (<40 mg/dL [males], <50 mg/dL [females]) and elevated triglycerides (≥ 150 mg/dL). A visual analog scale was used to define a perceived cardiovascular disease risk score. Mean age was 63.9 ± 9.7 years (64.6% males). The mean BMI was 29.1 ± 4.3 kg/m(2), and mean waist circumference 104.2 ± 12.7 cm (males), and 97.2 ± 14.0 cm (females). 29.4% were smokers, 76.4% had hypertension, 48.0% were diabetics, 24.7% had previous myocardial infarction, and 17.8% peripheral arterial disease. European guidelines classified 83.6% at very high cardiovascular risk. Recommended HDL-C levels were achieved by 50.1% of patients and 37.3% had triglycerides in the reference range. Target LDL-C was achieved by 8.8%. The overall atherogenic dyslipidemia prevalence was 27.1% (34.1% in diabetics). This prevalence in patients achieving target LDL-C was 21.4%. Cardiovascular risk perceived by patients was 4.3/10, while primary care physicians scored 5.7/10. When LDL-C levels are controlled, atherogenic dyslipidemia is more prevalent in those patients at highest cardiovascular risk and with diabetes. This highlights the importance of intervention strategies to prevent the residual vascular risk in this population. Both patients and physicians underestimated cardiovascular risk. Copyright © 2014 Sociedad Española de Arteriosclerosis. Published by Elsevier España. All rights reserved.

  6. Effect of 24 sessions of high-intensity aerobic interval training carried out at either high or moderate frequency, a randomized trial.

    Directory of Open Access Journals (Sweden)

    Håvard Hatle

    Full Text Available The training response of an intensified period of high-intensity exercise is not clear. Therefore, we compared the cardiovascular adaptations of completing 24 high-intensity aerobic interval training sessions carried out for either three or eight weeks, respectively.Twenty-one healthy subjects (23.0±2.1 years, 10 females completed 24 high-intensity training sessions throughout a time-period of either eight weeks (moderate frequency, MF or three weeks (high frequency, HF followed by a detraining period of nine weeks without any training. In both groups, maximal oxygen uptake (VO2max was evaluated before training, at the 9(th and 17(th session and four days after the final 24(th training session. In the detraining phase VO2max was evaluated after 12 days and thereafter every second week for eight weeks. Left ventricular echocardiography, carbon monoxide lung diffusion transfer factor, brachial artery flow mediated dilatation and vastus lateralis citrate maximal synthase activity was tested before and after training.The cardiovascular adaptation after HF training was delayed compared to training with MF. Four days after ending training the HF group showed no improvement (+3.0%, p = 0.126, whereas the MF group reached their highest VO2max with a 10.7% improvement (p<0.001: group difference p = 0.035. The HF group reached their highest VO2max (6.1% increase, p = 0.026 twelve days into the detraining period, compared to a concomitant reduction to 7.9% of VO2max (p<0.001 above baseline in the MF group (group difference p = 0.609.Both HF and MF training of high-intensity aerobic exercise improves VO2max. The cardiovascular adaptation following a HF programme of high-intensity exercise is however delayed compared to MF training.ClinicalTrials.gov NCT00733941.

  7. High sensitivity C reactive protein as a prognostic marker in patients with mild to moderate aortic valve stenosis during lipid-lowering treatment

    DEFF Research Database (Denmark)

    Blyme, Adam; Asferg, Camilla; Nielsen, Olav W

    2015-01-01

    AIMS: To assess the prognostic importance of high-sensitive C reactive protein (hsCRP) in patients with mild to moderate aortic valve stenosis during placebo or simvastatin/ezetimibe treatment in Simvastatin and Ezetimibe in Aortic Stenosis (SEAS). METHODS AND RESULTS: In 1620 SEAS patients, we m...

  8. Long-term effectiveness and cost-effectiveness of high versus low-to-moderate intensity resistance and endurance exercise interventions among cancer survivors

    NARCIS (Netherlands)

    Kampshoff, C. S.; van Dongen, J. M.; van Mechelen, W.; Schep, G.; Vreugdenhil, A.; Twisk, J. W.R.; Bosmans, J. E.; Brug, J.; Chinapaw, M. J.M.; Buffart, Laurien M.

    Purpose: This study aimed to evaluate the long-term effectiveness and cost-effectiveness of high intensity (HI) versus low-to-moderate intensity (LMI) exercise on physical fitness, fatigue, and health-related quality of life (HRQoL) in cancer survivors. Methods: Two hundred seventy-seven cancer

  9. Epitope specificity is critical for high and moderate avidity cytotoxic T lymphocytes associated with control of viral load and clinical disease in horses with equine infectious anemia virus

    International Nuclear Information System (INIS)

    Mealey, Robert H.; Zhang Baoshan; Leib, Steven R.; Littke, Matt H.; McGuire, Travis C.

    2003-01-01

    Equine infectious anemia virus (EIAV) is a lentivirus that causes persistent infections in horses. We hypothesized that high-avidity CTL specific for nonvariable epitopes might be associated with low viral load and minimal disease in EIAV-infected horses. To test this hypothesis, memory CTL (CTLm) responses were analyzed in two infected horses with high plasma viral loads and recurrent disease (progressors), and in two infected horses with low-to-undetectable viral loads and mild disease (nonprogressors). High-avidity CTLm in one progressor recognized an envelope gp90 epitope, and the data documented for the first time in EIAV that viral variation led to CTL escape. Each of the nonprogressors had high-to-moderate avidity CTLm directed against epitopes within Rev, including the nuclear export and nuclear localization domains. These results suggested that the epitope specificity of high- and moderate-avidity CTLm was an important determinant for disease outcome in the EIAV-infected horses examined

  10. Reynolds number calculation and applications for curved wall jets

    Directory of Open Access Journals (Sweden)

    Valeriu DRAGAN

    2014-09-01

    Full Text Available The current paper refers to the preliminary estimation of the Reynolds number for curved wall jets. This, in turn, can be a useful tool for controlling the boundary layer mesh size near a generic curved wall which is wetted by a thin, attached jet. The method relies on analytical calculations that link the local curvature of the wall with the pressure gradient and further, the local Reynolds number. Knowing the local Reynolds number distribution, a CFD user can tailor their mesh size to more exact specifications (e.g. y+=1 for k-omega RANS models and lower the risk that the mesh is too coarse or finer than necessary.

  11. Embedded Simultaneous Prompting Procedure to Teach STEM Content to High School Students with Moderate Disabilities in an Inclusive Setting

    Science.gov (United States)

    Heinrich, Sara; Collins, Belva C.; Knight, Victoria; Spriggs, Amy D.

    2016-01-01

    Effects of an embedded simultaneous prompting procedure to teach STEM (science, technology, engineering, math) content to three secondary students with moderate intellectual disabilities in an inclusive general education classroom were evaluated in the current study. Students learned discrete (i.e., geometric figures, science vocabulary, or use of…

  12. High Intensity Interval- vs Moderate Intensity- Training for Improving Cardiometabolic Health in Overweight or Obese Males: A Randomized Controlled Trial.

    Directory of Open Access Journals (Sweden)

    Gordon Fisher

    Full Text Available To compare the effects of six weeks of high intensity interval training (HIIT vs continuous moderate intensity training (MIT for improving body composition, insulin sensitivity (SI, blood pressure, blood lipids, and cardiovascular fitness in a cohort of sedentary overweight or obese young men. We hypothesized that HIIT would result in similar improvements in body composition, cardiovascular fitness, blood lipids, and SI as compared to the MIT group, despite requiring only one hour of activity per week compared to five hours per week for the MIT group.28 sedentary overweight or obese men (age, 20 ± 1.5 years, body mass index 29.5 ± 3.3 kg/m2 participated in a six week exercise treatment. Participants were randomly assigned to HIIT or MIT and evaluated at baseline and post-training. DXA was used to assess body composition, graded treadmill exercise test to measure cardiovascular fitness, oral glucose tolerance to measure SI, nuclear magnetic resonance spectroscopy to assess lipoprotein particles, and automatic auscultation to measure blood pressure.A greater improvement in VO2peak was observed in MIT compared to HIIT (11.1% vs 2.83%, P = 0.0185 in the complete-case analysis. No differences were seen in the intention to treat analysis, and no other group differences were observed. Both exercise conditions were associated with temporal improvements in % body fat, total cholesterol, medium VLDL, medium HDL, triglycerides, SI, and VO2peak (P < 0.05.Participation in HIIT or MIT exercise training displayed: 1 improved SI, 2 reduced blood lipids, 3 decreased % body fat, and 4 improved cardiovascular fitness. While both exercise groups led to similar improvements for most cardiometabolic risk factors assessed, MIT led to a greater improvement in overall cardiovascular fitness. Overall, these observations suggest that a relatively short duration of either HIIT or MIT training may improve cardiometabolic risk factors in previously sedentary overweight or

  13. High Intensity Interval- vs Moderate Intensity- Training for Improving Cardiometabolic Health in Overweight or Obese Males: A Randomized Controlled Trial.

    Science.gov (United States)

    Fisher, Gordon; Brown, Andrew W; Bohan Brown, Michelle M; Alcorn, Amy; Noles, Corey; Winwood, Leah; Resuehr, Holly; George, Brandon; Jeansonne, Madeline M; Allison, David B

    2015-01-01

    To compare the effects of six weeks of high intensity interval training (HIIT) vs continuous moderate intensity training (MIT) for improving body composition, insulin sensitivity (SI), blood pressure, blood lipids, and cardiovascular fitness in a cohort of sedentary overweight or obese young men. We hypothesized that HIIT would result in similar improvements in body composition, cardiovascular fitness, blood lipids, and SI as compared to the MIT group, despite requiring only one hour of activity per week compared to five hours per week for the MIT group. 28 sedentary overweight or obese men (age, 20 ± 1.5 years, body mass index 29.5 ± 3.3 kg/m2) participated in a six week exercise treatment. Participants were randomly assigned to HIIT or MIT and evaluated at baseline and post-training. DXA was used to assess body composition, graded treadmill exercise test to measure cardiovascular fitness, oral glucose tolerance to measure SI, nuclear magnetic resonance spectroscopy to assess lipoprotein particles, and automatic auscultation to measure blood pressure. A greater improvement in VO2peak was observed in MIT compared to HIIT (11.1% vs 2.83%, P = 0.0185) in the complete-case analysis. No differences were seen in the intention to treat analysis, and no other group differences were observed. Both exercise conditions were associated with temporal improvements in % body fat, total cholesterol, medium VLDL, medium HDL, triglycerides, SI, and VO2peak (P training displayed: 1) improved SI, 2) reduced blood lipids, 3) decreased % body fat, and 4) improved cardiovascular fitness. While both exercise groups led to similar improvements for most cardiometabolic risk factors assessed, MIT led to a greater improvement in overall cardiovascular fitness. Overall, these observations suggest that a relatively short duration of either HIIT or MIT training may improve cardiometabolic risk factors in previously sedentary overweight or obese young men, with no clear advantage between these

  14. Regular, high, and moderate intake of vegetables rich in antioxidants may reduce cataract risk in Central African type 2 diabetics

    Directory of Open Access Journals (Sweden)

    Mvitu M

    2012-06-01

    Full Text Available Moise Mvitu,1 Benjamin Longo-Mbenza,2 Dieudonné Tulomba,3 Augustin Nge31Department of Ophthalmology, University of Kinshasa, Democratic Republic of Congo; 2Faculty of Health Sciences, Walter Sisulu University, South Africa; 3Biostatistics Unit, Lomo Medical Center and Heart of Africa Center of Cardiology, Kinshasa, Democratic Republic of CongoBackground: Antioxidant nutrients found in popularly consumed vegetables, including red beans, are thought to prevent diabetic complications. In this study, we assessed the frequency and contributing factors of intake of fruits and vegetables rich in antioxidants, and we determined their impact on the prevention of diabetes-related cataract extraction.Methods: This was a cross-sectional study, run in Congo among 244 people with type 2 diabetes mellitus. An intake of ≥three servings of vegetables rich in antioxidants/day, intake of red beans, consumption of fruit, and cataract extraction were considered as dependent variables.Results: No patient reported a fruit intake. Intake of red beans was reported by 64 patients (26.2%, while 77 patients (31.6% reported ≥three servings of vegetables rich in antioxidants. High socioeconomic status (OR = 2.3; 95% CI: 1.1–12.5; P = 0.030 and moderate alcohol intake (OR = 4; 95% CI: 1.1–17.4; P = 0.049 were the independent determinants of eating ≥three servings of vegetables rich in antioxidants. Red beans intake (OR = 0.282; 95% CI: 0.115–0.687; P > 0.01 and eating ≥three servings of vegetables rich in antioxidants (OR = 0.256; 95% CI: 0.097–0.671; P = 0.006 were identified as independent and protective factors against the presence of cataracts (9.8% n = 24, whereas type 2 diabetes mellitus duration ≥3 years was the independent risk factor for cataract extraction (OR = 6.3; 95% CI: 2.1–19.2; P > 0.001 in the model with red beans intake and OR = 7.1; 95% CI: 2.3–22.2; P > 0.001 in the model with ≥three servings of vegetables rich in antioxidants

  15. Quantitative study on the effect of high-temperature curing at an early age on strength development of concrete. Experiment with mortar using moderate-heat portland cement

    International Nuclear Information System (INIS)

    Sugiyama, Hisashi; Chino, Shigeo

    1999-01-01

    The effect of high-temperature curing at an early age on the strength development of concrete using moderate-heat portland cement was quantitatively studied. High-temperature curing conditions were set so as to give systematic variations in the temperature-time factors. As a result, the integrated value of curing temperature during the period having a significant effect on the strength development was proposed as a parameter that expressed the degree of high-temperature curing. The effect of high-temperature curing on the strength development of concrete using moderate-heat portland cement could be exactly predicted with the integrated value of curing temperature during the period from 0 to 3 days. (author)

  16. A model for roll stall and the inherent stability modes of low aspect ratio wings at low Reynolds numbers

    Science.gov (United States)

    Shields, Matt

    The development of Micro Aerial Vehicles has been hindered by the poor understanding of the aerodynamic loading and stability and control properties of the low Reynolds number regime in which the inherent low aspect ratio (LAR) wings operate. This thesis experimentally evaluates the static and damping aerodynamic stability derivatives to provide a complete aerodynamic model for canonical flat plate wings of aspect ratios near unity at Reynolds numbers under 1 x 105. This permits the complete functionality of the aerodynamic forces and moments to be expressed and the equations of motion to solved, thereby identifying the inherent stability properties of the wing. This provides a basis for characterizing the stability of full vehicles. The influence of the tip vortices during sideslip perturbations is found to induce a loading condition referred to as roll stall, a significant roll moment created by the spanwise induced velocity asymmetry related to the displacement of the vortex cores relative to the wing. Roll stall is manifested by a linearly increasing roll moment with low to moderate angles of attack and a subsequent stall event similar to a lift polar; this behavior is not experienced by conventional (high aspect ratio) wings. The resulting large magnitude of the roll stability derivative, Cl,beta and lack of roll damping, Cl ,rho, create significant modal responses of the lateral state variables; a linear model used to evaluate these modes is shown to accurately reflect the solution obtained by numerically integrating the nonlinear equations. An unstable Dutch roll mode dominates the behavior of the wing for small perturbations from equilibrium, and in the presence of angle of attack oscillations a previously unconsidered coupled mode, referred to as roll resonance, is seen develop and drive the bank angle? away from equilibrium. Roll resonance requires a linear time variant (LTV) model to capture the behavior of the bank angle, which is attributed to the

  17. Increasing the Use of Student-Centered Pedagogies from Moderate to High Improves Student Learning and Attitudes about Biology

    Science.gov (United States)

    Connell, Georgianne L.; Donovan, Deborah A.; Chambers, Timothy G.

    2016-01-01

    Student-centered strategies are being incorporated into undergraduate classrooms in response to a call for reform. We tested whether teaching in an extensively student-centered manner (many active-learning pedagogies, consistent formative assessment, cooperative groups; the Extensive section) was more effective than teaching in a moderately student-centered manner (fewer active-learning pedagogies, less formative assessment, without groups; the Moderate section) in a large-enrollment course. One instructor taught both sections of Biology 101 during the same quarter, covering the same material. Students in the Extensive section had significantly higher mean scores on course exams. They also scored significantly higher on a content postassessment when accounting for preassessment score and student demographics. Item response theory analysis supported these results. Students in the Extensive section had greater changes in postinstruction abilities compared with students in the Moderate section. Finally, students in the Extensive section exhibited a statistically greater expert shift in their views about biology and learning biology. We suggest our results are explained by the greater number of active-learning pedagogies experienced by students in cooperative groups, the consistent use of formative assessment, and the frequent use of explicit metacognition in the Extensive section. PMID:26865643

  18. Ground effects on the stability of separated flow around an airfoil at low Reynolds numbers

    Science.gov (United States)

    He, Wei; Yu, Peng; Li, Larry K. B.

    2017-11-01

    We perform a BiGlobal stability analysis on the separated flow around a NACA 4415 airfoil at low Reynolds numbers (Re = 300 - 1000) and a high angle of attack α =20° with a focus on the effect of the airfoil's proximity to a moving ground. The results show that the most dominant perturbation is the Kelvin-Helmholtz mode and that this traveling mode becomes less unstable as the airfoil approaches the ground, although this stabilizing effect diminishes with increasing Reynolds number. By performing a Floquet analysis, we find that this ground effect can also stabilize secondary instabilities. This numerical-theoretical study shows that the ground can have a significant influence on the stability of separated flow around an airfoil at low Reynolds numbers, which could have implications for the design of micro aerial vehicles and for the understanding of natural flyers such as insects and birds. This work was supported by the Research Grants Council of Hong Kong (Project No. 16235716 and 26202815) and the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (the second phase) under Grant No.U1501501.

  19. Medieval Day at Reynolds: An Interdisciplinary Learning Event

    Science.gov (United States)

    Morrison, Nancy S.

    2012-01-01

    Medieval Day at Reynolds turned a typical Friday class day into an interdisciplinary learning event, which joined faculty and students into a community of learners. From classrooms issued tales of Viking and Mongol conquests, religious crusaders, deadly plague, and majestic cathedrals and art, all told by costumed faculty members with expertise in…

  20. Reynolds number dependence of drag reduction by rodlike polymers

    NARCIS (Netherlands)

    Amarouchene, Y.; Bonn, D.; Kellay, H.; Lo, T.-S.; L'vov, V.S.; Procaccia, I.

    2008-01-01

    We present experimental and theoretical results addressing the Reynolds number (Re) dependence of drag reduction by sufficiently large concentrations of rodlike polymers in turbulent wall-bounded flows. It is shown that when Re is small the drag is enhanced. On the other hand, when Re increases, the

  1. Hazardous Waste Cleanup: Reynolds Metals Company in Massena, New York

    Science.gov (United States)

    The Reynolds Metals Company is located at 194 County Route 45 in Massena, New York. The facility has been an active aluminum production plant since 1958. The 1,600-acre facility is bordered on the north by the St. Lawrence River and on the south by the

  2. Vegetation-Induced Roughness in Low-Reynold's Number Flows

    Science.gov (United States)

    Piercy, C. D.; Wynn, T. M.

    2008-12-01

    Wetlands are important ecosystems, providing habitat for wildlife and fish and shellfish production, water storage, erosion control, and water quality improvement and preservation. Models to estimate hydraulic resistance due to vegetation in emergent wetlands are crucial to good wetland design and analysis. The goal of this project is to improve modeling of emergent wetlands by linking properties of the vegetation to flow. Existing resistance equations such as Hoffmann (2004), Kadlec (1990), Moghadam and Kouwen (1997), Nepf (1999), and Stone and Shen (2002) were evaluated. A large outdoor vegetated flume was constructed at the Price's Fork Research Center near Blacksburg, Virginia to measure flow and water surface slope through woolgrass (Scirpus cyperinus), a common native emergent wetland plant. Measurements of clump and stem density, diameter, and volume, blockage factor, and stiffness were made after each set of flume runs. Flow rates through the flume were low (3-4 L/s) resulting in very low stem-Reynold's numbers (15-102). Since experimental flow conditions were in the laminar to transitional range, most of the models considered did not predict velocity or stage accurately except for conditions in which the stem-Reynold's number approached 100. At low stem-Reynold's numbers (drag coefficient is inversely proportional to the Reynold's number and can vary greatly with flow conditions. Most of the models considered assumed a stem-Reynold's number in the 100-105 range in which the drag coefficient is relatively constant and as a result did not predict velocity or stage accurately except for conditions in which the stem-Reynold's number approached 100. The only model that accurately predicted stem layer velocity was the Kadlec (1990) model since it does not make assumptions about flow regime; instead, the parameters are adjusted according to the site conditions. Future work includes relating the parameters used to fit the Kadlec (1990) model to measured vegetation

  3. High Reynolds number liquid layer flow with flexible walls

    Indian Academy of Sciences (India)

    School of Mathematics, University of Manchester, Manchester, M13 9PL, UK ... tions have potential application to aerodynamic and marine flows. .... Next, assume that the displacement of the free-surface induces a transverse pressure gradient.

  4. Aspects of magnetohydrodynamic duct flow at high magnetic Reynolds number

    International Nuclear Information System (INIS)

    Turner, R.B.

    1973-07-01

    The thesis is concerned with the performance of a flow coupler, which consists of an MHD generator coupled to an MHD pump so that one stream of fluid is induced to move by the motion of another. The flow coupler investigations include: the effects caused by eddy currents on the applied magnetic field and electric potential distribution, the velocity perturbation which occurs as a liquid flows through a magnetic field, devices in which large currents flow through a moving conductor and through an external circuit, and the movement of two conductors through the gap of a magnet. The expected performance of a flow coupler is calculated. (U.K.)

  5. Aerodynamic models for high-amplitude, low reynolds flapping airfoils

    OpenAIRE

    Morales Tirado, Elisa

    2015-01-01

    In this thesis a new aerodynamic model of insect-like flapping flight for micro air vehicles has been developed. The New Predicted Aerodynamic Model (NPAM) was based on the model described by Weis-Fogh model in Energetics of Hovering Flight in Hummingbirds and Drosophila. In order to achieved the NPAM some variations were introduced regarding the geometry of the problem under study and also some improvements was done to the theory developed by Weis-Fogh. To have the required ...

  6. High Reynolds number oscillations of a circular cylinder

    OpenAIRE

    Hirata, Miguel H.; Pereira, Luiz Antonio A.; Recicar, Jan N.; Moura, Washington H. de

    2008-01-01

    This paper concerns the numerical simulation of the flow around an oscillating circular cylinder, which moves with constant velocity in a quiescent Newtonian fluid with constant properties. For each time step of the simulation a number of discrete Lamb vortices is placed close to the body surface; the intensity of each of these is determined such as to satisfy the no-slip boundary condition. The aerodynamic loads acting on the surface of cylinder are computed using the integral formulation de...

  7. Streamwise Fluctuations of Vortex Breakdown at High Reynolds Numbers

    National Research Council Canada - National Science Library

    Connelly, Jonathan S

    2006-01-01

    This thesis deals with the characterization of the dependence on the flow geometry of the stream wise fluctuations of the stagnation point of vortex breakdown in axisymmetric tubes and over delta wing aircraft...

  8. High Reynolds Number Wave Force Investigation in a Wave Flume.

    Science.gov (United States)

    1985-03-01

    RESULTS 43 6.0 CONCLUSIONS 45 7.0 REFERENCES 49 8.0 ACKNOWLEDGEMENTS 51 9.0 TABLES 53 10.0 FIGURES 93 11.0 APPENDIX A" 11.1 Druck Pressure Transducer...adjoining test cylinder by 0.7 mm, which had a negligible influence on the resulting measurements. After the Druck pressure transducers were installed and...dC C 3d 4 ;88dC 38dC CI8 cninfl"nV0to .t" o ,t in cv d-. ,0 en w . nC M..r nin - -0 - I!- I!- V! - -i !V L4JN C; .0 d C0000000 40000008 o .6 C

  9. Equinoctial spread-F occurrence at low latitudes in different longitude sectors under moderate and high solar activity

    Science.gov (United States)

    Pietrella, M.; Pezzopane, M.; Fagundes, P. R.; de Jesus, R.; Supnithi, P.; Klinngam, S.; Ezquer, R. G.; Cabrera, M. A.

    2017-11-01

    A comparative study aimed to investigate the equatorial and low-latitude spread-F occurrences for moderate solar activity (MSA) and high solar activity (HSA), was carried out considering concurrent observations made in some ionospheric stations, which identify three separate longitudinal sectors: Chiang Mai (CGM; 18.8° N, 98.9° E, mag. Lat. 13.2° N) and Chumphon (CPN; 10.7° N, 99.4° E, mag. Lat. 3.2° N), Thailand; Palmas (PAL; 10.2° S, 311.8° E, mag. Lat. 0.9° S) and São José dos Campos (SJC; 23.2° S, 314.1° E, mag. Lat. 14.0° S), Brazil; Tucumán (TUC; 26.9° S, 294.6° E, mag. Lat. 16.8° S), Argentina. Spread-F phenomena recorded during the equinoctial months of September and October 2010, March and April 2011, for MSA, March and April 2014, September and October 2014, for HSA, were classified in two different modes: range spread-F (RSF) and frequency spread-F (FSF). The satellite trace (ST) occurrence was also investigated as possible precursor of spread-F events. When comparing the results of equatorial (CPN and PAL) and low-latitude (CGM, SJC, and TUC) stations, some common features independently of the solar activity emerge: (1) a prevalence of RSF signatures is observed in the time interval 20:00-03:00 LT, while FSF occurrences prevail in the time interval 03:00-06:00 LT; (2) STs are confirmed to be a possible precursor of RSF occurrences. For HSA, at equatorial latitudes, spread-F occurrences in the Thai sector (CPN) are higher than those observed in the Brazilian sector (PAL). When comparing the results of low-latitude stations of CGM, SJC, and TUC some unusual aspects characterizing the morphology of spread-F occurrences emerge: (1) contrary to the Thai and Argentine sectors, in the Brazilian sector (SJC), RSF and FSF appearances in September, for HSA, are observed with relatively long persistence times between about 03:00-06:00 LT and 01:00-03:00 LT respectively, while balanced RSF and FSF occurrences with short persistence times are

  10. Moderator Configuration Options for ESS

    DEFF Research Database (Denmark)

    Zanini, L.; Batkov, K.; Klinkby, Esben Bryndt

    2016-01-01

    The current, still evolving status of the design and the optimization work for the moderator configuration for the European Spallation Source is described. The moderator design has been strongly driven by the low-dimensional moderator concept recently proposed for use in spallation neutron sources...... or reactors. Quasi-two dimensional, disc- or tube-shaped moderators,can provide strong brightness increase (factor of 3 or more) with respect to volume para-H2moderators, which constitute the reference, state-of-the-art technology for high-intensity coupled moderators. In the design process other, more...... conventional, principles were also considered,such as the importance of moderator positioning, of the premoderator, and beam extraction considerations. Different design and configuration options are evaluated and compared with the reference volume moderator configuration described in the ESS Technical Design...

  11. Comparison of affective responses during and after low volume high-intensity interval exercise, continuous moderate- and continuous high-intensity exercise in active, untrained, healthy males.

    Science.gov (United States)

    Niven, Ailsa; Thow, Jacqueline; Holroyd, Jack; Turner, Anthony P; Phillips, Shaun M

    2018-09-01

    This study compared affective responses to low volume high-intensity interval exercise (HIIE), moderate-intensity continuous exercise (MICE) and high-intensity continuous exercise (HICE). Twelve untrained males ([Formula: see text] 48.2 ± 6.7 ml·kg -1 ·min -1 ) completed MICE (30 min cycle at 85% of ventilatory threshold (VT)), HICE (cycle at 105% of VT matched with MICE for total work), and HIIE (10 x 6 s cycle sprints with 60 s recovery). Affective valence and perceived activation were measured before exercise, post warm-up, every 20% of exercise time, and 1, 5, 10, and 15 min post-exercise. Affective valence during exercise declined by 1.75 ± 2.42, 1.17 ± 1.99, and 0.42 ± 1.38 units in HICE, HIIE, and MICE, respectively, but was not statistically influenced by trial (P = 0.35), time (P = 0.06), or interaction effect (P = 0.08). Affective valence during HICE and HIIE was consistently less positive than MICE. Affective valence post-exercise was not statistically influenced by trial (P = 0.10) and at 5 min post-exercise exceeded end-exercise values (P = 0.048). Circumplex profiles showed no negative affect in any trial. Affective responses to low volume HIIE are similar to HICE but remain positive and rebound rapidly, suggesting it may be a potential alternative exercise prescription.

  12. Increasing the Use of Student-Centered Pedagogies from Moderate to High Improves Student Learning and Attitudes about Biology.

    Science.gov (United States)

    Connell, Georgianne L; Donovan, Deborah A; Chambers, Timothy G

    2016-01-01

    Student-centered strategies are being incorporated into undergraduate classrooms in response to a call for reform. We tested whether teaching in an extensively student-centered manner (many active-learning pedagogies, consistent formative assessment, cooperative groups; the Extensive section) was more effective than teaching in a moderately student-centered manner (fewer active-learning pedagogies, less formative assessment, without groups; the Moderate section) in a large-enrollment course. One instructor taught both sections of Biology 101 during the same quarter, covering the same material. Students in the Extensive section had significantly higher mean scores on course exams. They also scored significantly higher on a content postassessment when accounting for preassessment score and student demographics. Item response theory analysis supported these results. Students in the Extensive section had greater changes in postinstruction abilities compared with students in the Moderate section. Finally, students in the Extensive section exhibited a statistically greater expert shift in their views about biology and learning biology. We suggest our results are explained by the greater number of active-learning pedagogies experienced by students in cooperative groups, the consistent use of formative assessment, and the frequent use of explicit metacognition in the Extensive section. © 2016 G. L. Connell, D. A. Donovan, and T. G. Chambers. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  13. High-intensity interval running is perceived to be more enjoyable than moderate-intensity continuous exercise: implications for exercise adherence.

    Science.gov (United States)

    Bartlett, Jonathan D; Close, Graeme L; MacLaren, Don P M; Gregson, Warren; Drust, Barry; Morton, James P

    2011-03-01

    The aim of this study was to objectively quantify ratings of perceived enjoyment using the Physical Activity Enjoyment Scale following high-intensity interval running versus moderate-intensity continuous running. Eight recreationally active men performed two running protocols consisting of high-intensity interval running (6 × 3 min at 90% VO(2max) interspersed with 6 × 3 min active recovery at 50% VO(2max) with a 7-min warm-up and cool down at 70% VO(2max)) or 50 min moderate-intensity continuous running at 70% VO(2max). Ratings of perceived enjoyment after exercise were higher (P running compared with continuous running (88 ± 6 vs. 61 ± 12) despite higher (P running may be relevant for improving exercise adherence, since running is a low-cost exercise intervention requiring no exercise equipment and similar relative exercise intensities have previously induced health benefits in patient populations.

  14. Treatment patterns and low-density lipoprotein cholesterol (LDL-C) goal attainment among patients receiving high- or moderate-intensity statins.

    Science.gov (United States)

    Fox, Kathleen M; Tai, Ming-Hui; Kostev, Karel; Hatz, Maximilian; Qian, Yi; Laufs, Ulrich

    2018-05-01

    European clinical guidelines recommend a low-density lipoprotein cholesterol (LDL-C) goal of C goal attainment among atherosclerotic CV disease (ASCVD) patients with various utilization patterns of moderate- or high-intensity statins in routine care. This retrospective cohort study used electronic medical records data from the QuintilesIMS® Disease Analyzer (> 2 million individuals annually) to identify ASCVD (coronary atherosclerosis, stable/unstable angina, myocardial infarction, ischemic stroke, transient ischemic attack, aneurysm, peripheral artery disease) patients on moderate-/high-intensity statin in Germany. Proportion of patients with LDL-C C value for each patient (index) in 2012, 2013, and 2014, while on statin. Treatment patterns were assessed for patients with at least 1 year of post-index follow-up. Results were stratified by year and treatment pattern [no change, switch, dose up-/down-titration, discontinuation (≥ 90 day gap)]. In > 14,000 patients assessed in each year (mean age 71 years, 35% female, 8-12% taking high-intensity statins), approximately 80% had LDL-C ≥ 70 mg/dL. Treatment patterns were assessed for most (88-93%) patients. Approximately 79-81% of patients made no change to statin regimens, 1% switched statins, 14-16% discontinued; 1% of moderate-intensity patients up-titrated, and 3% of all patients down-titrated. LDL-C goal attainment in these treatment pattern groups was 20, 16-24, 17, 11-14, and 17-19%, respectively. Majority of ASCVD patients had LDL-C ≥ 70 mg/dL while on moderate-/high-intensity statins. Despite low LDL-C goal attainment, few patients changed their treatment regimens.

  15. High-protein, low-fat, short-term diet results in less stress and fatigue than moderate-protein moderate-fat diet during weight loss in male weightlifters: a pilot study.

    Science.gov (United States)

    Helms, Eric R; Zinn, Caryn; Rowlands, David S; Naidoo, Ruth; Cronin, John

    2015-04-01

    Athletes risk performance and muscle loss when dieting. Strategies to prevent losses are unclear. This study examined the effects of two diets on anthropometrics, strength, and stress in athletes. This double-blind crossover pilot study began with 14 resistance-trained males (20-43 yr) and incurred one dropout. Participants followed carbohydrate-matched, high-protein low-fat (HPLF) or moderate-protein moderate-fat (MPMF) diets of 60% habitual calories for 2 weeks. Protein intakes were 2.8g/kg and 1.6g/kg and mean fat intakes were 15.4% and 36.5% of calories, respectively. Isometric midthigh pull (IMTP) and anthropometrics were measured at baseline and completion. The Daily Analysis of Life Demands of Athletes (DALDA) and Profile of Mood States (POMS) were completed daily. Outcomes were presented statistically as probability of clinical benefit, triviality, or harm with effect sizes (ES) and qualitative assessments. Differences of effect between diets on IMTP and anthropometrics were likely or almost certainly trivial, respectively. Worse than normal scores on DALDA part A, part B and the part A "diet" item were likely more harmful (ES 0.32, 0.4 and 0.65, respectively) during MPMF than HPLF. The POMS fatigue score was likely more harmful (ES 0.37) and the POMS total mood disturbance score (TMDS) was possibly more harmful (ES 0.29) during MPMF than HPLF. For the 2 weeks observed, strength and anthropometric differences were minimal while stress, fatigue, and diet-dissatisfaction were higher during MPMF. A HPLF diet during short-term weight loss may be more effective at mitigating mood disturbance, fatigue, diet dissatisfaction, and stress than a MPMF diet.

  16. Greater effects of high- compared with moderate-intensity interval training on cardio-metabolic variables, blood leptin concentration and ratings of perceived exertion in obese adolescent females.

    Science.gov (United States)

    Racil, G; Coquart, J B; Elmontassar, W; Haddad, M; Goebel, R; Chaouachi, A; Amri, M; Chamari, K

    2016-06-01

    This study examined the effects of high- vs. moderate-intensity interval training on cardiovascular fitness, leptin levels and ratings of perceived exertion (RPE) in obese female adolescents. Forty-seven participants were randomly assigned to one of three groups receiving either a 1:1 ratio of 15 s of effort comprising moderate-intensity interval training (MIIT at 80% maximal aerobic speed: MAS) or high-intensity interval training (HIIT at 100% MAS), with matched 15 s recovery at 50% MAS, thrice weekly, or a no-training control group. The HIIT and MIIT groups showed improved (p HIIT group showed decreased waist circumference (WC) (p = 0.017). The effect of exercise on maximal oxygen uptake (VO2max) was significant (p = 0.019, ES = 0.48 and p = 0.010, ES = 0.57, HIIT and MIIT, respectively). The decrease of rate-pressure product (RPP) (p HIIT and MIIT, respectively) followed the positive changes in resting heart rate and blood pressures. Blood glucose, insulin level and the homeostasis model assessment index for insulin decreased (p HIIT and MIIT, respectively. In the post-intervention period, blood leptin was strongly associated with %BF (p HIIT and MIIT groups, respectively, while RPE was strongly associated with BM (p HIIT group. The results suggest that high-intensity interval training may produce more positive effects on health determinants in comparison with the same training mode at a moderate intensity.

  17. Differential metabolic effects of constant moderate versus high intensity interval training in high-fat fed mice: possible role of muscle adiponectin.

    Science.gov (United States)

    Martinez-Huenchullan, Sergio F; Maharjan, Babu Raja; Williams, Paul F; Tam, Charmaine S; Mclennan, Susan V; Twigg, Stephen M

    2018-02-01

    Exercise regimens may have differing effects in the presence of obesity. In addition to being fat derived, adiponectin has recently been described as a myokine that regulates insulin sensitivity, which may link to exercise-related metabolic benefits in obesity. Whether skeletal muscle adiponectin varies in different exercise modalities is unclear. This study investigated the comparative effects of 10 weeks of endurance constant-moderate intensity exercise (END) with high intensity interval training (HIIT), on metabolic outcomes, including muscle adiponectin in a mouse model of diet-induced obesity. Ten-week-old male C57BL/6 mice were fed a high-fat diet (HFD) (45% FAT) or standard CHOW diet ab libitum and underwent one of three training regimes: (1) no exercise, (2) END, or (3) HIIT (8 bouts of 2.5 min with eight periods of rest of 2.5 min) for 10 weeks (3 × 40 min sessions/week). Chow-fed mice acted as controls. Compared with HFD alone, both training programs similarly protected against body weight gain (HFD = 45 ± 2; END = 37 ± 2; HIIT = 36 ± 2 g), preserved lean/fat tissue mass ratio (HFD = 0.64 ± 0.09; END = 0.34 ± 0.13; HIIT = 0.33 ± 0.13), and improved blood glucose excursion during an insulin tolerance test (HFD = 411 ± 54; END = 350 ± 57; HIIT = 320 ± 66 arbitrary units [AU]). Alterations in fasting glycemia, insulinemia, and AST/ALT ratios were prevented only by END. END, but not HIIT increased skeletal muscle adiponectin mRNA (14-fold; P HIIT induced a milder increase (2.4-fold). Compared with HFD, neither END nor HIIT altered circulating low (LMW) or high (HMW) molecular weight adiponectin forms. Furthermore, only END prevented the HFD downregulation of PGC1α (P < 0.05) mRNA levels downstream of muscle adiponectin. These data show that different training programs affect muscle adiponectin to differing degrees. Together these results suggest that END is a more effective regimen to prevent HFD

  18. Perceived vulnerability moderates the relations between the use of protective behavioral strategies and alcohol use and consequences among high-risk young adults.

    Science.gov (United States)

    Garcia, Tracey A; Fairlie, Anne M; Litt, Dana M; Waldron, Katja A; Lewis, Melissa A

    2018-06-01

    Drinking protective behavioral strategies (PBS) have been associated with reductions in alcohol use and alcohol-related consequences in young adults. PBS subscales, Limiting/Stopping (LS), Manner of Drinking (MOD), and Serious Harm Reduction (SHR), have been examined in the literature; LS, MOD, and SHR have mixed support as protective factors. Understanding moderators between PBS and alcohol use and related consequences is an important development in PBS research in order to delineate when and for whom PBS use is effective in reducing harm from alcohol use. Perceptions of vulnerability to negative consequences, included in health-risk models, may be one such moderator. The current study examined whether two types of perceived vulnerability (perceived vulnerability when drinking; perceived vulnerability in uncomfortable/unfamiliar situations) moderated the relations between LS, MOD, SHR strategies and alcohol use and related negative consequences. High-risk young adults (N = 400; 53.75% female) recruited nationally completed measures of PBS, alcohol use and related consequences, and measures of perceived vulnerability. Findings demonstrated that perceived vulnerability when drinking moderated the relations between MOD strategies and alcohol use. The interactions between perceived vulnerability when drinking and PBS did not predict alcohol-related consequences. Perceived vulnerability in unfamiliar/uncomfortable social situations moderated relations between MOD strategies and both alcohol use and related negative consequences; no other significant interactions emerged. Across both perceived vulnerability types and MOD strategies, those with the highest levels of perceived vulnerability and who used MOD strategies the most had the greatest decrements in alcohol use and related negative consequences. Prevention and intervention implications are discussed. Copyright © 2018. Published by Elsevier Ltd.

  19. Can High-Tech Ventures Benefit from Government Guanxi and Business Guanxi? The Moderating Effects of Environmental Turbulence

    Directory of Open Access Journals (Sweden)

    Dejin Su

    2017-01-01

    Full Text Available The construct of guanxi has become an interesting topic for analyzing how to do business more effectively and successfully in China’s economic transition period. Drawing on the guanxi strategy theory, this study examines when government guanxi (guanxi with the government and its officials and business guanxi (guanxi with the business sectors matter to new venture performance under two typical turbulent environments (institutional turbulence and market turbulence. According to empirical results using original data from 146 new ventures in clusters driven by China’s local governments, both government guanxi and business guanxi were positively related to new venture performance, and market turbulence was an important contextual factor influencing performance benefits of guanxi. However, the results reveal no moderating effects of institutional turbulence on direct relationships. Furthermore, the study provides a better conceptual and empirical understanding of why market turbulence is a double-edged sword for performance implications of guanxi in the rapidly changing business environment.

  20. Flow through collapsible tubes at low Reynolds numbers. Applicability of the waterfall model.

    Science.gov (United States)

    Lyon, C K; Scott, J B; Wang, C Y

    1980-07-01

    The applicability of the waterfall model was tested using the Starling resistor and different viscosities of fluids to vary the Reynolds number. The waterfall model proved adequate to describe flow in the Starling resistor model only at very low Reynolds numbers (Reynolds number less than 1). Blood flow characterized by such low Reynolds numbers occurs only in the microvasculature. Thus, it is inappropriate to apply the waterfall model indiscriminately to flow through large collapsible veins.

  1. 75 FR 1596 - Grant of Authority for Subzone Status, Reynolds Packaging LLC (Aluminum Foil Liner Stock...

    Science.gov (United States)

    2010-01-12

    ... Status, Reynolds Packaging LLC (Aluminum Foil Liner Stock), Louisville, Kentucky Pursuant to its...-purpose subzone at the aluminum foil liner stock manufacturing and distribution facilities of Reynolds... manufacturing and distribution of aluminum foil liner stock and aluminum foil at the facilities of Reynolds...

  2. Reynolds Stress Closure for Inertial Frames and Rotating Frames

    Science.gov (United States)

    Petty, Charles; Benard, Andre

    2017-11-01

    In a rotating frame-of-reference, the Coriolis acceleration and the mean vorticity field have a profound impact on the redistribution of kinetic energy among the three components of the fluctuating velocity. Consequently, the normalized Reynolds (NR) stress is not objective. Furthermore, because the Reynolds stress is defined as an ensemble average of a product of fluctuating velocity vector fields, its eigenvalues must be non-negative for all turbulent flows. These fundamental properties (realizability and non-objectivity) of the NR-stress cannot be compromised in computational fluid dynamic (CFD) simulations of turbulent flows in either inertial frames or in rotating frames. The recently developed universal realizable anisotropic prestress (URAPS) closure for the NR-stress depends explicitly on the local mean velocity gradient and the Coriolis operator. The URAPS-closure is a significant paradigm shift from turbulent closure models that assume that dyadic-valued operators associated with turbulent fluctuations are objective.

  3. Effects of Reynold's number on flight performance of turbofan engine

    Energy Technology Data Exchange (ETDEWEB)

    Kozu, Masao; Yajima, Satoshi [Defense Agency Tokyo (Japan); Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan))

    1988-12-10

    Concerning the performance of the F3-30 turbofan engine which is carried on the intermediate trainer XT-4 of the Air Self Defense Force, tests simulating its flight conditions were conducted at the Altitude Test Facility (ATF) of the Arnold Engineering Development Center (AEDC), U.S. Air Force in order to adjust the effect of Reynold's number corresponding to the flight condition. This report summarizes the results of the above tests. As the results of the tests, it was revealed that in order to calculate with precision the flight performance of the F3-30 turbofan engine, it was required to adjust Reynold's number against the following figures, namely the fan air flow, compressor air flow, compressor adiabatic efficiency, low pressure turbine gas flow and low pressure turbine adiabatic efficiency. The engine performance calculated by using the above adjustments agreed well with the measured values of the ATF tests. 7 refs., 17 figs., 1 tab.

  4. Identifying a Superfluid Reynolds Number via Dynamical Similarity.

    Science.gov (United States)

    Reeves, M T; Billam, T P; Anderson, B P; Bradley, A S

    2015-04-17

    The Reynolds number provides a characterization of the transition to turbulent flow, with wide application in classical fluid dynamics. Identifying such a parameter in superfluid systems is challenging due to their fundamentally inviscid nature. Performing a systematic study of superfluid cylinder wakes in two dimensions, we observe dynamical similarity of the frequency of vortex shedding by a cylindrical obstacle. The universality of the turbulent wake dynamics is revealed by expressing shedding frequencies in terms of an appropriately defined superfluid Reynolds number, Re(s), that accounts for the breakdown of superfluid flow through quantum vortex shedding. For large obstacles, the dimensionless shedding frequency exhibits a universal form that is well-fitted by a classical empirical relation. In this regime the transition to turbulence occurs at Re(s)≈0.7, irrespective of obstacle width.

  5. A Reynolds stress model for near-wall turbulence

    Science.gov (United States)

    Durbin, P. A.

    1993-01-01

    The paper formulates a tensorially consistent near-wall second-order closure model. Redistributive terms in the Reynolds stress equations are modeled by an elliptic relaxation equation in order to represent strongly nonhomogeneous effects produced by the presence of walls; this replaces the quasi-homogeneous algebraic models that are usually employed, and avoids the need for ad hoc damping functions. The model is solved for channel flow and boundary layers with zero and adverse pressure gradients. Good predictions of Reynolds stress components, mean flow, skin friction, and displacement thickness are obtained in various comparisons to experimental and direct numerical simulation data. The model is also applied to a boundary layer flowing along a wall with a 90-deg, constant-radius, convex bend.

  6. Turbulent flows at very large Reynolds numbers: new lessons learned

    International Nuclear Information System (INIS)

    Barenblatt, G I; Prostokishin, V M; Chorin, A J

    2014-01-01

    The universal (Reynolds-number-independent) von Kármán–Prandtl logarithmic law for the velocity distribution in the basic intermediate region of a turbulent shear flow is generally considered to be one of the fundamental laws of engineering science and is taught universally in fluid mechanics and hydraulics courses. We show here that this law is based on an assumption that cannot be considered to be correct and which does not correspond to experiment. Nor is Landau's derivation of this law quite correct. In this paper, an alternative scaling law explicitly incorporating the influence of the Reynolds number is discussed, as is the corresponding drag law. The study uses the concept of intermediate asymptotics and that of incomplete similarity in the similarity parameter. Yakov Borisovich Zeldovich played an outstanding role in the development of these ideas. This work is a tribute to his glowing memory. (100th anniversary of the birth of ya b zeldovich)

  7. Dynamical System Analysis of Reynolds Stress Closure Equations

    Science.gov (United States)

    Girimaji, Sharath S.

    1997-01-01

    In this paper, we establish the causality between the model coefficients in the standard pressure-strain correlation model and the predicted equilibrium states for homogeneous turbulence. We accomplish this by performing a comprehensive fixed point analysis of the modeled Reynolds stress and dissipation rate equations. The results from this analysis will be very useful for developing improved pressure-strain correlation models to yield observed equilibrium behavior.

  8. Craig Reynolds: Recognized for Excellence in Medicine | Poster

    Science.gov (United States)

    The Distinguished Alumni Award is one of the most prestigious awards at the University of Iowa Roy J. and Lucille A. Carver College of Medicine. This award recognizes influential alumni who have achieved excellence in the art and science of medicine. One of this year’s recipients is Craig Reynolds, Ph.D., associate director, NCI. When asked how he felt about receiving this

  9. Fluid Mechanics of Aquatic Locomotion at Large Reynolds Numbers

    OpenAIRE

    Govardhan, RN; Arakeri, JH

    2011-01-01

    Abstract | There exist a huge range of fish species besides other aquatic organisms like squids and salps that locomote in water at large Reynolds numbers, a regime of flow where inertial forces dominate viscous forces. In the present review, we discuss the fluid mechanics governing the locomotion of such organisms. Most fishes propel themselves by periodic undulatory motions of the body and tail, and the typical classification of their swimming modes is based on the fraction of their body...

  10. Reynolds number dependency in equilibrium two-dimensional turbulence

    Science.gov (United States)

    Bracco, A.; McWilliams, J.

    2009-04-01

    We use the Navier-Stokes equations for barotropic turbulence as a zero-order approximation of chaotic space-time patterns and equilibrium distributions that mimic turbulence in geophysical flows. In this overly-simplified set-up for which smooth-solutions exist, we investigate if is possible to bound the uncertainty associated with the numerical domain discretization, i.e. with the limitation imposed by the Reynolds number range we can explore. To do so we analyze a series of stationary barotropic turbulence simulations spanning a large range of Reynolds numbers and run over a three year period for over 300,000 CPU hours. We find a persistent Reynolds number dependency in the energy power spectra and second order vorticity structure function, while distributions of dynamical quantities such as velocity, vorticity, dissipation rates and others are invariant in shape and have variances scaling with the viscosity coefficient according to simple power-laws. The relevance to this work to the possibility of conceptually reducing uncertainties in climate models will be discussed.

  11. Reynolds number effects on mixing due to topological chaos.

    Science.gov (United States)

    Smith, Spencer A; Warrier, Sangeeta

    2016-03-01

    Topological chaos has emerged as a powerful tool to investigate fluid mixing. While this theory can guarantee a lower bound on the stretching rate of certain material lines, it does not indicate what fraction of the fluid actually participates in this minimally mandated mixing. Indeed, the area in which effective mixing takes place depends on physical parameters such as the Reynolds number. To help clarify this dependency, we numerically simulate the effects of a batch stirring device on a 2D incompressible Newtonian fluid in the laminar regime. In particular, we calculate the finite time Lyapunov exponent (FTLE) field for three different stirring protocols, one topologically complex (pseudo-Anosov) and two simple (finite-order), over a range of viscosities. After extracting appropriate measures indicative of both the amount of mixing and the area of effective mixing from the FTLE field, we see a clearly defined Reynolds number range in which the relative efficacy of the pseudo-Anosov protocol over the finite-order protocols justifies the application of topological chaos. More unexpectedly, we see that while the measures of effective mixing area increase with increasing Reynolds number for the finite-order protocols, they actually exhibit non-monotonic behavior for the pseudo-Anosov protocol.

  12. Reynolds and Maxwell stress measurements in the reversed field pinch experiment Extrap-T2R

    Science.gov (United States)

    Vianello, N.; Antoni, V.; Spada, E.; Spolaore, M.; Serianni, G.; Cavazzana, R.; Bergsåker, H.; Cecconello, M.; Drake, J. R.

    2005-08-01

    The complete Reynolds stress (RS) has been measured in the edge region of the Extrap-T2R reversed field pinch experiment. The RS exhibits a strong gradient in the region where a high E × B shear takes place. Experimental results show this gradient to be almost entirely due to the electrostatic contribution. This has been interpreted as experimental evidence of flow generation via turbulence mechanism. The scales involved in flow generation are deduced from the frequency decomposition of RS tensor. They are found related to magnetohydrodynamic activity but are different with respect to the scales responsible for turbulent transport.

  13. Reynolds and Maxwell stress measurements in the reversed field pinch experiment Extrap-T2R

    International Nuclear Information System (INIS)

    Vianello, N.; Antoni, V.; Spada, E.; Spolaore, M.; Serianni, G.; Cavazzana, R.; Bergsaaker, H.; Cecconello, M.; Drake, J.R.

    2005-01-01

    The complete Reynolds stress (RS) has been measured in the edge region of the Extrap-T2R reversed field pinch experiment. The RS exhibits a strong gradient in the region where a high E x B shear takes place. Experimental results show this gradient to be almost entirely due to the electrostatic contribution. This has been interpreted as experimental evidence of flow generation via turbulence mechanism. The scales involved in flow generation are deduced from the frequency decomposition of RS tensor. They are found related to magnetohydrodynamic activity but are different with respect to the scales responsible for turbulent transport

  14. Turbulent Reynolds stress and quadrant event activity in wind flow over a coastal foredune

    Science.gov (United States)

    Chapman, Connie A.; Walker, Ian J.; Hesp, Patrick A.; Bauer, Bernard O.; Davidson-Arnott, Robin G. D.

    2012-05-01

    Recent research on quasi-instantaneous turbulent kinematic Reynolds stresses (RS, - u'w') and decomposed quadrant event activity (e.g., ejections and sweeps) over dunes in fluvial settings and in wind tunnels has shown that turbulent stresses at the toe of a dune often exceed time-averaged, streamwise shear stress (ρ u * 2) estimates. It is believed that semi-coherent turbulent structures are conveyed toward the bed along concave streamlines in this region and that impact of these structures cause fluctuations in local surface stresses that assist in grain entrainment. This has been hypothesized to explain how sand is supplied to the windward slope through a region of flow stagnation. Toward the crest, surface stress increases and becomes dominated by streamwise accelerations resulting from streamline compression and convexity that suppress vertical motions. High-frequency (32 Hz) measurements of turbulent wind flow from 3-D ultrasonic anemometers are analyzed for oblique onshore flow over a vegetated coastal foredune in Prince Edward Island, Canada. Reynolds stress and quadrant activity distributions varied with height (0.60 m and 1.66 m) and location over the dune. In general, quadrant 2 ejection (u' 0) and quadrant 4 sweep activity (u' > 0, w' 0, w' > 0) and quadrant 3 inward interaction (u' dune and may help to explain sand transport potential and dune maintenance. For example, areas with a high frequency of ejection and sweep activity may have higher rates of sediment entrainment and transport, whereas areas with lower ejection and sweep activity and an increase in outward and inward interactions, which contribute negatively to Reynolds stress generation, may experience a greater potential for deposition. Further research on associations between quadrant event activity and coincident sand transport is required to confirm this hypothesis and the resultant significance of the flow exuberance effect in aeolian dune morphodynamics.

  15. Reynolds stress turbulence model applied to two-phase pressurized thermal shocks in nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Mérigoux, Nicolas, E-mail: nicolas.merigoux@edf.fr; Laviéville, Jérôme; Mimouni, Stéphane; Guingo, Mathieu; Baudry, Cyril

    2016-04-01

    Highlights: • NEPTUNE-CFD is used to model two-phase PTS. • k-ε model did produce some satisfactory results but also highlights some weaknesses. • A more advanced turbulence model has been developed, validated and applied for PTS. • Coupled with LIM, the first results confirmed the increased accuracy of the approach. - Abstract: Nuclear power plants are subjected to a variety of ageing mechanisms and, at the same time, exposed to potential pressurized thermal shock (PTS) – characterized by a rapid cooling of the internal Reactor Pressure Vessel (RPV) surface. In this context, NEPTUNE-CFD is used to model two-phase PTS and give an assessment on the structural integrity of the RPV. The first available choice was to use standard first order turbulence model (k-ε) to model high-Reynolds number flows encountered in Pressurized Water Reactor (PWR) primary circuits. In a first attempt, the use of k-ε model did produce some satisfactory results in terms of condensation rate and temperature field distribution on integral experiments, but also highlights some weaknesses in the way to model highly anisotropic turbulence. One way to improve the turbulence prediction – and consequently the temperature field distribution – is to opt for more advanced Reynolds Stress turbulence Model. After various verification and validation steps on separated effects cases – co-current air/steam-water stratified flows in rectangular channels, water jet impingements on water pool free surfaces – this Reynolds Stress turbulence Model (R{sub ij}-ε SSG) has been applied for the first time to thermal free surface flows under industrial conditions on COSI and TOPFLOW-PTS experiments. Coupled with the Large Interface Model, the first results confirmed the adequacy and increased accuracy of the approach in an industrial context.

  16. Experiments on a low aspect ratio wing at low Reynolds numbers

    Science.gov (United States)

    Morse, Daniel R.

    At the start of the 21st century much of the focus of aircraft design has been turned to unmanned aerial vehicles (UAVs) which generally operate at much lower speeds in higher risk areas than manned aircraft. One subset of UAVs are Micro Air Vehicles (MAVs) which usually are no larger than 20cm and rely on non-traditional shapes to generate lift at very low velocities. This purpose of this work is to describe, in detail with experimental methods, the flow field around a low aspect ratio wing operating at low Reynolds numbers and at high angles of attack. Quantitative measurements are obtained by Three Component Time Resolved Particle Image Velocimetry (3C TR PIV) which describe the mean and turbulent flow field. This research focuses on the leading edge separation zone and the vortex shedding process which occurs at the leading edge. Streamwise wing tip vortices which dominate the lift characteristics are described with flow visualization and 3C TR PIV measurements. Turbulent Kinetic Energy (TKE) is described at the leading edge over several angles of attack. Turbulent Reynolds stresses in all three directions are described over the wing span and several Reynolds numbers. Two primary cyclic processes are observed within the flow field; one low frequency oscillation in the separated region and one high frequency event associated with leading edge vortex formation and convection. Two length scales are proposed and are shown to match well with each other, one based on leading edge vortex shedding frequency and convective velocity and the other based on mean vortex separation distance. A new method of rendering velocity frequency content over large data sets is proposed and used to illustrate the different frequencies observed at the leading edge.

  17. Live performance of male broilers subjected to constant or increasing air velocities at moderate temperatures with a high dew point.

    Science.gov (United States)

    Dozier, W A; Lott, B D; Branton, S L

    2005-08-01

    This study examined the effects of varying air velocities vs. a constant air velocity with a cyclic temperature curve of 25-30-25 degrees C and a dew point of 23 degrees C on broilers from 28 to 49 d of age. Four replicate trials were conducted. In each trial, 742 male broilers were randomly allocated to 6 floor pens or 2 air velocity tunnels, with each tunnel consisting of 4 pens. Bird density, feeder, and waterer space were similar across all pens (53 birds/ pen; 0.07 m2/bird). The treatments were control (still air), constant air velocity of 120 m/min, and increasing air velocity (90 m/min from 28 to 35 d, 120 m/min from 36 to 42 d, and 180 m/min from 43 to 49 d). Birds grown in a still air environment gained less weight, consumed less feed, and converted feed less efficiently between 28 and 49 d than birds subjected to moving air (constant or increasing). Growth responses between the air velocity treatments were similar from 28 to 35 and 36 to 42 d of age. Increasing air velocity to 180 m/min improved (P < or = 0.02) the growth rate of broilers from 43 to 49 d of age over birds receiving an air velocity of 120 m/min, but the incidence of mortality was not affected. These results provide evidence that increasing air velocity from 120 to 180 m/min is beneficial to broilers weighing 2.5 kg or greater when exposed to moderate temperatures.

  18. The incidence of kidney injury for patients treated with a high-potency versus moderate-potency statin regimen after an acute coronary syndrome.

    Science.gov (United States)

    Sarma, Amy; Cannon, Christopher P; de Lemos, James; Rouleau, Jean L; Lewis, Eldrin F; Guo, Jianping; Mega, Jessica L; Sabatine, Marc S; O'Donoghue, Michelle L

    2014-05-01

    Observational studies have raised concerns that high-potency statins increase the risk of acute kidney injury. We therefore examined the incidence of kidney injury across 2 randomized trials of statin therapy. PROVE IT-TIMI 22 enrolled 4162 subjects after an acute coronary syndrome (ACS) and randomized them to atorvastatin 80 mg/day versus pravastatin 40 mg/day. A-to-Z enrolled 4497 subjects after ACS and randomized them to a high-potency (simvastatin 40 mg/day × 1 months, then simvastatin 80 mg/day) versus a delayed moderate-potency statin strategy (placebo × 4 months, then simvastatin 20 mg/day). Serum creatinine was assessed centrally at serial time points. Adverse events (AEs) relating to kidney injury were identified through database review. Across both trials, mean serum creatinine was similar between treatment arms at baseline and throughout follow-up. In A-to-Z, the incidence of a 1.5-fold or ≥ 0.3 mg/dL rise in serum creatinine was 11.4% for subjects randomized to a high-potency statin regimen versus 12.4% for those on a delayed moderate-potency regimen (odds ratio [OR], 0.91; 95% confidence interval [CI], 0.76 to 1.10; P=0.33). In PROVE IT-TIMI 22, the incidence was 9.4% for subjects randomized to atorvastatin 80 mg/day and 10.6% for subjects randomized to pravastatin 40 mg/day (OR, 0.88; 95% CI, 0.71 to 1.09; P=0.25). Consistent results were observed for different kidney injury thresholds and in individuals with diabetes mellitus or with moderate renal dysfunction. The incidence of kidney injury-related adverse events (AEs) was not statistically different for patients on a high-potency versus moderate-potency statin regimen (OR, 1.06; 95% CI, 0.68 to 1.67; P=0.78). For patients enrolled in 2 large randomized trials of statin therapy after ACS, the use of a high-potency statin regimen did not increase the risk of kidney injury.

  19. Cold moderators at ORNL

    International Nuclear Information System (INIS)

    Lucas, A. T.

    1997-09-01

    The Advanced Neutron Source (ANS) cold moderators were not an 'Oak Ridge first', but would have been the largest both physically and in terms of cold neutron flux. Two cold moderators were planned each 410 mm in diameter and containing about 30L of liquid deuterium. They were to be completely independent of each other. A modular system design was used to provide greater reliability and serviceability. When the ANS was terminated, upgrading of the resident High Flux Isotope Reactor (HFIR) was examined and an initial study was made into the feasibility of adding a cold source. Because the ANS design was modular, it was possible to use many identical design features. Sub-cooled liquid at 4 bar abs was initially chosen for the HFIR design concept, but this was subsequently changed to 15 bar abs to operate above the critical pressure. As in the ANS, the hydrogen will operate at a constant pressure throughout the temperature range and a completely closed loop with secondary containment was adopted. The heat load of 2 kW made the heat flux comparable with that of the ANS. Subsequent studies into the construction of cryogenic moderators for the proposed new Synchrotron Neutron source indicated that again many of the same design concepts could be used. By connecting the two cold sources together in series, the total heat load of 2 kW is very close to that of the HFIR allowing a very similar supercritical hydrogen system to be configured. The two hydrogen moderators of the SNS provide a comparable heat load to the HFIR moderator. It is subsequently planned to connect the two in series and operate from a single cold loop system, once again using supercritical hydrogen. The spallation source also provided an opportunity to re-examine a cold pellet solid methane moderator operating at 20K.

  20. Moderately Low Magnesium Intake Impairs Growth of Lean Body Mass in Obese-Prone and Obese-Resistant Rats Fed a High-Energy Diet

    Directory of Open Access Journals (Sweden)

    Jesse Bertinato

    2016-04-01

    Full Text Available The physical and biochemical changes resulting from moderately low magnesium (Mg intake are not fully understood. Obesity and associated co-morbidities affect Mg metabolism and may exacerbate Mg deficiency and physiological effects. Male rats selectively bred for diet-induced obesity (OP, obese-prone or resistance (OR, obese-resistant were fed a high-fat, high-energy diet containing moderately low (LMg, 0.116 ± 0.001 g/kg or normal (NMg, 0.516 ± 0.007 g/kg Mg for 13 weeks. The growth, body composition, mineral homeostasis, bone development, and glucose metabolism of the rats were examined. OP and OR rats showed differences (p < 0.05 in many physical and biochemical measures regardless of diet. OP and OR rats fed the LMg diet had decreased body weight, lean body mass, decreased femoral size (width, weight, and volume, and serum Mg and potassium concentrations compared to rats fed the NMg diet. The LMg diet increased serum calcium (Ca concentration in both rat strains with a concomitant decrease in serum parathyroid hormone concentration only in the OR strain. In the femur, Mg concentration was reduced, whereas concentrations of Ca and sodium were increased in both strains fed the LMg diet. Plasma glucose and insulin concentrations in an oral glucose tolerance test were similar in rats fed the LMg or NMg diets. These results show that a moderately low Mg diet impairs the growth of lean body mass and alters femoral geometry and mineral metabolism in OP and OR rats fed a high-energy diet.

  1. Pharmacokinetics, safety, and efficacy of APF530 (extended-release granisetron) in patients receiving moderately or highly emetogenic chemotherapy: results of two Phase II trials

    International Nuclear Information System (INIS)

    Gabrail, Nashat; Yanagihara, Ronald; Spaczyński, Marek; Cooper, William; O’Boyle, Erin; Smith, Carrie; Boccia, Ralph

    2015-01-01

    Despite advances with new therapies, a significant proportion of patients (>30%) suffer delayed-onset chemotherapy-induced nausea and vomiting (CINV) despite use of antiemetics. APF530 is a sustained-release subcutaneous (SC) formulation of granisetron for preventing CINV. APF530 pharmacokinetics, safety, and efficacy were studied in two open-label, single-dose Phase II trials (C2005-01 and C2007-01, respectively) in patients receiving moderately emetogenic chemotherapy or highly emetogenic chemotherapy. In C2005-01, 45 patients received APF530 250, 500, or 750 mg SC (granisetron 5, 10, or 15 mg, respectively). In C2007-01, 35 patients were randomized to APF530 250 or 500 mg SC. Injections were given 30 to 60 minutes before single-day moderately emetogenic chemotherapy or highly emetogenic chemotherapy. Plasma granisetron was measured from predose to 168 hours after study drug administration. Safety and efficacy were also evaluated. APF530 pharmacokinetics were dose proportional, with slow absorption and elimination of granisetron after a single SC dose. Median time to maximum plasma concentration and half-life were similar for APF530 250 and 500 mg in both trials, with no differences between the groups receiving moderately and highly emetogenic chemotherapy. Exposure to granisetron was maintained at a therapeutic level over the delayed-onset phase, at least 168 hours. Adverse events in both trials were as expected for granisetron; injection site reactions (eg, erythema and induration) were predominantly mild and seen in ≤20% of patients. Complete responses (no emesis, with no rescue medication) were obtained in the acute, delayed, and overall phases in ≥80% and ≥75% of patients in both trials with the 250 and 500 mg doses, respectively. After a single injection of APF530, there were dose-proportional pharmacokinetics and sustained concentrations of granisetron over 168 hours. The 250 and 500 mg doses were well tolerated and maintained therapeutic granisetron

  2. Is right ventricular mid-septal pacing superior to apical pacing in patients with high degree atrio-ventricular block and moderately depressed left ventricular function?

    Science.gov (United States)

    Chen, Kang; Mao, Ye; Liu, Shao-hua; Wu, Qiong; Luo, Qing-zhi; Pan, Wen-qi; Jin, Qi; Zhang, Ning; Ling, Tian-you; Chen, Ying; Gu, Gang; Shen, Wei-feng; Wu, Li-qun

    2014-06-01

    We are aimed to investigate whether right ventricular mid-septal pacing (RVMSP) is superior to conventional right ventricular apical pacing (RVAP) in improving clinical functional capacity and left ventricular ejection fraction (LVEF) for patients with high-degree atrio-ventricular block and moderately depressed left ventricle (LV) function. Ninety-two patients with high-degree atrio-ventricular block and moderately reduced LVEF (ranging from 35% to 50%) were randomly allocated to RVMSP (n=45) and RVAP (n=47). New York Heart Association (NYHA) functional class, echocardiographic LVEF, and distance during a 6-min walk test (6MWT) were determined at 18 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured using an enzyme-linked immunosorbent assay (ELISA) kit. Compared with baseline, NYHA functional class remained unchanged at 18 months, distance during 6MWT (485 m vs. 517 m) and LVEF (36.7% vs. 41.8%) were increased, but BNP levels were reduced (2352 pg/ml vs. 710 pg/ml) in the RVMSP group compared with those in the RVAP group, especially in patients with LVEF 35%-40% (for all comparisons, Pfunction capacity and LV function measurements were not significantly changed in patients with RVAP, despite the pacing measurements being similar in both groups, such as R-wave amplitude and capture threshold. RVMSP provides a better clinical utility, compared with RVAP, in patients with high-degree atrioventricular block and moderately depressed LV function whose LVEF levels ranged from 35% to 40%.

  3. Assessment of Reynolds stresses tensor reconstruction methods for synthetic turbulent inflow conditions. Application to hybrid RANS/LES methods

    International Nuclear Information System (INIS)

    Laraufie, Romain; Deck, Sébastien

    2013-01-01

    Highlights: • Present various Reynolds stresses reconstruction methods from a RANS-SA flow field. • Quantify the accuracy of the reconstruction methods for a wide range of Reynolds. • Evaluate the capabilities of the overall process (Reconstruction + SEM). • Provide practical guidelines to realize a streamwise RANS/LES (or WMLES) transition. -- Abstract: Hybrid or zonal RANS/LES approaches are recognized as the most promising way to accurately simulate complex unsteady flows under current computational limitations. One still open issue concerns the transition from a RANS to a LES or WMLES resolution in the stream-wise direction, when near wall turbulence is involved. Turbulence content has then to be prescribed at the transition to prevent from turbulence decay leading to possible flow relaminarization. The present paper aims to propose an efficient way to generate this switch, within the flow, based on a synthetic turbulence inflow condition, named Synthetic Eddy Method (SEM). As the knowledge of the whole Reynolds stresses is often missing, the scope of this paper is focused on generating the quantities required at the SEM inlet from a RANS calculation, namely the first and second order statistics of the aerodynamic field. Three different methods based on two different approaches are presented and their capability to accurately generate the needed aerodynamic values is investigated. Then, the ability of the combination SEM + Reconstruction method to manufacture well-behaved turbulence is demonstrated through spatially developing flat plate turbulent boundary layers. In the mean time, important intrinsic features of the Synthetic Eddy method are pointed out. The necessity of introducing, within the SEM, accurate data, with regards to the outer part of the boundary layer, is illustrated. Finally, user’s guidelines are given depending on the Reynolds number based on the momentum thickness, since one method is suitable for low Reynolds number while the

  4. Acute growth hormone administration causes exaggerated increases in plasma lactate and glycerol during moderate to high intensity bicycling in trained young men

    DEFF Research Database (Denmark)

    Lange, K.H.; Larsson, B.; Flyvbjerg, A.

    2002-01-01

    ). In the placebo trial, all subjects completed the exercise protocol without any difficulties. In contrast, two subjects were not able to complete the exercise protocol in the GH trial, and one subject barely managed to complete the protocol. In addition, GH administration resulted in exaggerated increases...... in increased whole body fat oxidation (indirect calorimetry). Plasma glucose was, on average, 9% higher during exercise after GH administration compared with placebo (P ... during 90 min of subsequent bicycling at moderate to high intensity. The exaggerated increase in plasma lactate may be associated with substantially decreased exercise performance....

  5. Moderate-to-high-intensity training and a hypocaloric Mediterranean diet enhance endothelial progenitor cells and fitness in subjects with the metabolic syndrome.

    Science.gov (United States)

    Fernández, Juan Marcelo; Rosado-Álvarez, Daniel; Da Silva Grigoletto, Marzo Edir; Rangel-Zúñiga, Oriol Alberto; Landaeta-Díaz, Leslie Lorena; Caballero-Villarraso, Javier; López-Miranda, José; Pérez-Jiménez, Francisco; Fuentes-Jiménez, Francisco

    2012-09-01

    A reduction in EPC (endothelial progenitor cell) number could explain the development and progression of atherosclerosis in the MetS (metabolic syndrome). Although much research in recent years has focused on the Mediterranean dietary pattern and the MetS, the effect of this diet with/without moderate-to-high-intensity endurance training on EPCs levels and CrF (cardiorespiratory fitness) remains unclear. In the present study, the objective was to assess the effect of a Mediterranean diet hypocaloric model with and without moderate-to-high-intensity endurance training on EPC number and CrF of MetS patients. Thus 45 MetS patients (50-66 years) were randomized to a 12-week intervention with the hypocaloric MeD (Mediterranean diet) or the MeDE (MeD plus moderate-to-high-intensity endurance training). Training included two weekly supervised sessions [80% MaxHR (maximum heart rate); leg and arm pedalling] and one at-home session (65-75% MaxHR; walking controlled by heart rate monitors). Changes in: (i) EPC number [CD34(+)KDR(+) (kinase insert domain-containing receptor)], (ii) CrF variables and (iii) MetS components and IRH (ischaemic reactive hyperaemia) were determined at the end of the study. A total of 40 subjects completed all 12 weeks of the study, with 20 in each group. The MeDE led to a greater increase in EPC numbers and CrF than did the MeD intervention (P ≤ 0.001). In addition, a positive correlation was observed between the increase in EPCs and fitness in the MeDE group (r=0.72; r(2)=0.52; P ≤ 0.001). Body weight loss, insulin sensitivity, TAGs (triacylglycerols) and blood pressure showed a greater decrease in the MeDE than MeD groups. Furthermore, IRH was only improved after the MeDE intervention. In conclusion, compliance with moderate-to-high-intensity endurance training enhances the positive effects of a model of MeD on the regenerative capacity of endothelium and on the fitness of MetS patients.

  6. Effect of tapering after a period of high-volume sprint interval training on running performance and muscular adaptations in moderately trained runners

    DEFF Research Database (Denmark)

    Skovgaard, Casper; Almquist, Nicki Winfield; Kvorning, Thue

    2018-01-01

    The effect of tapering following a period of high-volume sprint interval training (SIT) and a basic volume of aerobic training on performance and muscle adaptations in moderately trained runners was examined. Eleven (8 males, 3 females) runners (maximum oxygen uptake (VO2-max): 56.8±2.9 mL·min(-1...... running test at 90% of vVO2-max to exhaustion (RRT). In addition, a biopsy from m. vastus lateralis was obtained at rest. Performance during RRT was better (P... at 60% of vVO2-max was lower (P

  7. Airfoil-Wake Modification with Gurney Flap at Low Reynolds Number

    Science.gov (United States)

    Gopalakrishnan Meena, Muralikrishnan; Taira, Kunihiko; Asai, Keisuke

    2018-04-01

    The complex wake modifications produced by a Gurney flap on symmetric NACA airfoils at low Reynolds number are investigated. Two-dimensional incompressible flows over NACA 0000 (flat plate), 0006, 0012 and 0018 airfoils at a Reynolds number of $Re = 1000$ are analyzed numerically to examine the flow modifications generated by the flaps for achieving lift enhancement. While high lift can be attained by the Gurney flap on airfoils at high angles of attack, highly unsteady nature of the aerodynamic forces are also observed. Analysis of the wake structures along with the lift spectra reveals four characteristic wake modes (steady, 2S, P and 2P), influencing the aerodynamic performance. The effects of the flap over wide range of angles of attack and flap heights are considered to identify the occurrence of these wake modes, and are encapsulated in a wake classification diagram. Companion three-dimensional simulations are also performed to examine the influence of three-dimensionality on the wake regimes. The spanwise instabilities that appear for higher angles of attack are found to suppress the emergence of the 2P mode. The use of the wake classification diagram as a guidance for Gurney flap selection at different operating conditions to achieve the required aerodynamic performance is discussed.

  8. Repeated exposure to high-frequency spanking and child externalizing behavior across the first decade: a moderating role for cumulative risk.

    Science.gov (United States)

    MacKenzie, Michael J; Nicklas, Eric; Brooks-Gunn, Jeanne; Waldfogel, Jane

    2014-12-01

    This study used the Fragile Families and Child Well-Being Study to examine the effects of repeated exposure to harsh parenting on child externalizing behavior across the first decade of life, and a moderating role for cumulative ecological risk. Maternal report of harsh parenting, defined as high frequency spanking, was assessed at age 1, 3, 5, and 9, along with child externalizing at age 9 (N=2,768). Controlling for gender, race, maternal nativity, and city of residence, we found a cumulative risk index to significantly moderate the effects of repeated harsh parenting on child behavior, with the effects of repeated high-frequency spanking being amplified for those experiencing greater levels of cumulative risk. Harsh parenting, in the form of high frequency spanking, remains a too common experience for children, and results demonstrate that the effects of repeated exposure to harsh parenting across the first decade are amplified for those children already facing the most burden. Copyright © 2014. Published by Elsevier Ltd.

  9. Application of a Cohesive Zone Model for Simulating Fatigue Crack Growth from Moderate to High ΔK Levels of Inconel 718

    Directory of Open Access Journals (Sweden)

    Huan Li

    2018-01-01

    Full Text Available A cyclic cohesive zone model is applied to characterize the fatigue crack growth behavior of a IN718 superalloy which is frequently used in aerospace components. In order to improve the limitation of fracture mechanics-based models, besides the predictions of the moderate fatigue crack growth rates at the Paris’ regime and the high fatigue crack growth rates at the high stress intensity factor ΔK levels, the present work is also aimed at simulating the material damage uniformly and examining the influence of the cohesive model parameters on fatigue crack growth systematically. The gradual loss of the stress-bearing ability of the material is considered through the degradation of a novel cohesive envelope. The experimental data of cracked specimens are used to validate the simulation result. Based on the reasonable estimation for the model parameters, the fatigue crack growth from moderate to high ΔK levels can be reproduced under the small-scale yielding condition, which is in fair agreement with the experimental results.

  10. Aerodynamic characteristics and thermal structure of nonpremixed reacting swirling wakes at low Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Rong F. [Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei (China); Yen, Shun C. [Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung (China)

    2008-12-15

    The aerodynamic characteristics and thermal structure of uncontrolled and controlled swirling double-concentric jet flames at low Reynolds numbers are experimentally studied. The swirl and Reynolds numbers are lower than 0.6 and 2000, respectively. The flow characteristics are diagnosed by the laser-light-sheet-assisted Mie scattering flow visualization method and particle image velocimetry (PIV). The thermal structure is measured by a fine-wire thermocouple. The flame shapes, combined images of flame and flow, velocity vector maps, streamline patterns, velocity and turbulence distributions, flame lengths, and temperature distributions are discussed. The flow patterns of the no-control case exhibit an open-top, single-ring vortex sitting on the blockage disc with a jetlike swirling flow evolving from the central disc face toward the downstream area. The rotation direction and size of the near-disc vortex, as well as the flow properties, change in different ranges of annulus swirl number and therefore induce three characteristic flame modes: weak swirling flame, lifted flame, and turbulent reattached flame. Because the near-disc vortex is open-top, the radial dispersion of the fuel-jet fluids is not significantly enhanced by the annulus swirling flow. The flows of the reacting swirling double-concentric jets at such low swirl and Reynolds numbers therefore present characteristics of diffusion jet flames. In the controlled case, the axial momentum of the central fuel jet is deflected radially by a control disc placed above the blockage disc. This arrangement can induce a large near-disc recirculation bubble and high turbulence intensities. The enhanced mixing hence tremendously shortens the flame length and enlarges the flame width. (author)

  11. Penentuan Kondisi Optimum Ukuran Partikel dan Bilangan Reynold Pada Sintesis Bioplastik Berbasis Sorgum

    Directory of Open Access Journals (Sweden)

    Yuli Darni

    2011-12-01

    Full Text Available The article reported the laboratory experiment to obtain the optimal condition of particle size and Reynold Number of bioplastic film based on the plastic package standard of High Density Polyethylene (HDPE.  Particle sizes of starch were varied at 63, 90, 106, 600, and 1000 micron, and the mixing rate were changes at 190, 252, 313, 375, and 437 rpm. The concentration of chitosan and gliserol added to solution were set as constant variable as 20 and 10 wt %, respectively. The temperature of gelatinitation was also fixed at 95OC. The fabricated of bioplastic film were characterized for mechanical property such as tensile strength, elongation at break and Modulus Young by using a  Universal Testing Machine. The  morphology of film sheets were observed by using a scanning electron microscopy (SEM. Moreover, the obtained film was also investigated for water uptake parameter. The result showed that the mechanical properties were improve by increasing mixing rate at smallest particle sizes of starch. The water uptakes shows decrease at hight mixing rate. SEM images showed that the morphology of bioplastic was almost simmilar to the morphology of  HDPE.  The optimum condition was found that the best film was obtained at particle size of starch 63 micron, Reynold Number of  959, with mixing rate of  375 rpm. The mechanical value at best condition was 19.27%, 757.046 Mpa, and 142.875 for elongation, Modulus Young,  and tensile strength, respectively. Keywords: bioplastic, reynold Number, starch, sorgum

  12. Reynolds stress analysis of EMHD-controlled wall turbulence. Part I. Streamwise forcing

    International Nuclear Information System (INIS)

    Crawford, C.H.; Karniadakis, G.E.

    1997-01-01

    In this work we investigate numerically turbulent flow of low electrical conductivity fluid subject to electro-magnetic (EMHD) forcing. The configuration is similar to the one considered in the experimental work of Henoch and Stace [Phys. Fluids 7, 1371 (1995)] but in a channel geometry. The lower wall of the channel is covered with alternating streamwise electrodes and magnets to create a Lorentz force in the positive streamwise direction. Two cases are considered in detail corresponding to interaction parameter values of 0.4 (case 1) and 0.1 (case 2). The effect of switching off and on the electrodes is also studied for the two cases. At the Reynolds number considered (Re τ ∼200), a drag increase was obtained for all cases, in agreement with the experiments of Henoch and Stace. A Reynolds stress analysis was performed based on a new decomposition of the gradients normal to the wall of the Reynolds stress -u'v'. It was found that the vortex stretching term w'w 2 ' and the spanwise variation of the stress component u'w' are responsible for the drag increase. More specifically, the term ∂(u'w')/∂x 3 is associated with secondary vortical motions in the near-wall and becomes large and positive for large shear stress in regions where fluid is moving toward the wall. In contrast, negative values are associated with regions of lower shear where fluid is being lifted away from the wall. Unlike the unperturbed flow, in the controlled flow high speed near-wall streamwise jets are present (case 1) even in the time-averaged fields. Other changes in turbulence structure are quantified using streak spacing, vortex lines, vorticity quadrant analysis, and plots of the rms value of the vorticity angle. copyright 1997 American Institute of Physics

  13. Test Review: Reynolds, C. R., & Kamphaus, R. W. (2003). "RIAS--Reynolds Intellectual Assessment Scales." Lutz, FL--Psychological Assessment Resources, Inc.

    Science.gov (United States)

    Dombrowski, Stefan C.; Mrazik, Martin

    2008-01-01

    In this article, the authors review the Reynolds Intellectual Assessment Scales (RIAS; Reynolds & Kamphaus, 2003), an individually administered test of intelligence for use with individuals between the ages of 3 and 94. The RIAS represents the newest intelligence test on the marketplace and incorporates the most current intelligence test theory…

  14. Association between childhood maltreatment and non-medical prescription opioid use among Chinese senior high school students: The moderating role of gender.

    Science.gov (United States)

    Lei, Yiling; Xi, Chuhao; Li, Pengsheng; Luo, Min; Wang, Wanxin; Pan, Siyuan; Gao, Xue; Xu, Yan; Huang, Guoliang; Deng, Xueqing; Guo, Lan; Lu, Ciyong

    2018-08-01

    Non-medical prescription opioid use (NMPOU) and childhood maltreatment are currently serious problems among adolescents worldwide, and childhood maltreatment may be associated with the increased rates of NMPOU. This study examined the specific associations between particular types of childhood maltreatment and lifetime NMPOU and assessed whether gender has a moderating effect on these associations. A 3-stage, stratified cluster, randomized sampling method was used to collect data from 11,194 high school students in Chongqing. The prevalence of the lifetime NMPOU among senior high school students in Chongqing was 7.7%. Physical abuse (AOR = 1.11, 95% CI = 1.07-1.14), emotional abuse (AOR = 1.05, 95% CI = 1.03-1.08), sexual abuse (AOR = 1.04, 95% CI = 1.01-1.07), physical neglect (AOR = 1.06, 95% CI = 1.04-1.09), and emotional neglect (AOR = 1.03, 95% CI = 1.02-1.04) were all positively associated with lifetime NMPOU. The moderating effects of gender on emotional abuse (P = 0.004) and sexual abuse (P = 0.019) were statistically significant in the adjusted model of lifetime NMPOU. According to the stratification analyses in which the male and female students were analyzed separately, female students who previously experienced emotional/sexual abuse had a higher prevalence of lifetime NMPOU. The study sample only contained school students and cross-sectional design limited our ability to make causal inferences. Childhood maltreatment was positively associated with lifetime NMPOU, and gender had a moderating effect on the associations between childhood maltreatment and lifetime NMPOU. Early identification of and intervention for childhood maltreatment victims, particularly female victims, may help reduce the lifetime risk of NMPOU. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Dynamic behavior and microstructural evolution during moderate to high strain rate hot deformation of a Fe–Ni–Cr alloy (alloy 800H)

    International Nuclear Information System (INIS)

    Cao, Yu; Di, Hongshuang; Zhang, Jiecen; Yang, Yaohua

    2015-01-01

    The objective of the study is to fundamentally understand the dynamic behavior of alloy 800H at moderate to high strain rate using hot compression tests and propose nucleation mechanism associated with dynamic crystallization (DRX). We firstly investigated the dynamic behavior of alloy 800H with industrial scale strain rates using hot compression tests and adiabatic correction was performed to correct as-measured flow curves. Secondly, a Johnson–Cook model was established by using the corrected data and could give a precise prediction of elevated temperature flow stress for the studied alloy. Finally, the nucleation mechanism of DRX grains at high strain rates was studied. The results showed that the predominant nucleation mechanism for DRX is the formation of “bulge” at parent grain boundary. Additionally, the fragmentation of original grain at low deformation temperatures and the twinning near the bulged regions at high deformation temperatures also accelerate the DRX process

  16. Dynamic behavior and microstructural evolution during moderate to high strain rate hot deformation of a Fe-Ni-Cr alloy (alloy 800H)

    Science.gov (United States)

    Cao, Yu; Di, Hongshuang; Zhang, Jiecen; Yang, Yaohua

    2015-01-01

    The objective of the study is to fundamentally understand the dynamic behavior of alloy 800H at moderate to high strain rate using hot compression tests and propose nucleation mechanism associated with dynamic crystallization (DRX). We firstly investigated the dynamic behavior of alloy 800H with industrial scale strain rates using hot compression tests and adiabatic correction was performed to correct as-measured flow curves. Secondly, a Johnson-Cook model was established by using the corrected data and could give a precise prediction of elevated temperature flow stress for the studied alloy. Finally, the nucleation mechanism of DRX grains at high strain rates was studied. The results showed that the predominant nucleation mechanism for DRX is the formation of "bulge" at parent grain boundary. Additionally, the fragmentation of original grain at low deformation temperatures and the twinning near the bulged regions at high deformation temperatures also accelerate the DRX process.

  17. Occupational status moderates the association between current perceived stress and high blood pressure: evidence from the IPC cohort study

    Science.gov (United States)

    Wiernik, Emmanuel; Pannier, Bruno; Czernichow, Sébastien; Nabi, Hermann; Hanon, Olivier; Simon, Tabassome; Simon, Jean-Marc; Thomas, Frédérique; Bean, Kathy; Consoli, Silla; Danchin, Nicolas; Lemogne, Cédric

    2013-01-01

    Although lay beliefs commonly relate high blood pressure to psychological stress exposure, research findings are conflicting. This study examined the association between current perceived stress and high blood pressure and explored the potential impact of occupational status on this association. Resting blood pressure was measured in 122,816 adults (84,994 men), aged ≥30 years (mean age ± standard deviation: 46.8±9.9 years), without history of cardiovascular and renal disease and not on either psychotropic or antihypertensive drugs. High blood pressure was defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg. Perceived stress in the past month was measured with the 4-item perceived stress scale. A total of 33,154 participants (27.0%) had high blood pressure (151±14/90±9 mmHg). After adjustment for all variables except occupational status, perceived stress was associated with high blood pressure (odds ratio for a 5-point increase: 1.06, 95% confidence interval: [1.03–1.09]). This association was no longer significant after additional adjustment for occupational status (odds ratio: 1.01 [0.99–1.04]). There was a significant interaction (phigh blood pressure among individuals of high occupational status (odds ratio: 0.91, [0.87–0.96]) but positively associated among those of low status (odds ratio: 1.10, [1.03–1.17]) or unemployed (odds ratio: 1.13, [1.03–1.24]). Sensitivity analyses yielded similar results. The association between current perceived stress and blood pressure depends upon occupational status. This interaction may account for previous conflicting results and warrants further studies to explore its underlying mechanisms. PMID:23319539

  18. The Big Fish Down Under: Examining Moderators of the "Big-Fish-Little-Pond" Effect for Australia's High Achievers

    Science.gov (United States)

    Seaton, Marjorie; Marsh, Herbert W.; Yeung, Alexander Seeshing; Craven, Rhonda

    2011-01-01

    Big-fish-little-pond effect (BFLPE) research has demonstrated that academic self-concept is negatively affected by attending high-ability schools. This article examines data from large, representative samples of 15-year-olds from each Australian state, based on the three Program for International Student Assessment (PISA) databases that focus on…

  19. Validation of KENO V.a for highly enriched uranium systems with hydrogen and/or carbon moderation

    International Nuclear Information System (INIS)

    Elliott, E.P.; Vornehm, R.G.; Dodds, H.L. Jr.

    1993-01-01

    This paper describes the validation in accordance with ANSI/ANS-8.1-1983(R1988) of KENO V.a using the 27-group ENDF/B-IV cross-section library for systems containing highly-enriched uranium, carbon, and hydrogen and for systems containing highly-enriched uranium and carbon with high carbon to uranium (C/U) atomic ratios. The validation has been performed for two separate computational platforms: an IBM 3090 mainframe and an HP 9000 Model 730 workstation, both using the Oak Ridge Y-12 Plant Nuclear Criticality Safety Software (NCSS) code package. Critical experiments performed at the Oak Ridge Critical Experiments Facility, in support of the Rover reactor program, and at the Pajarito site at Los Alamos National Laboratory were identified as having the constituents desired for this validation as well as sufficient experimental detail to allow accurate construction of KENO V.a calculational models. Calculated values of k eff for the Rover experiments, which contain uranium, carbon, and hydrogen, are between 1.0012 ± 0.0026 and 1.0245 ± 0.0023. Calculation of the Los Alamos experiments, which contain uranium and carbon at high C/U ratios, yields values of k eff between 0.9746 ± 0.0028 and 0.9983 ± 0.0027. Safety criteria can be established using this data for both types of systems

  20. Control of wing-tip vortex using winglets at low Reynolds number

    Science.gov (United States)

    Cho, Seunghyun; Choi, Haecheon

    2014-11-01

    Winglets are considered as one of the effective devices for reducing induced drag, and thus many studies have been conducted, but mainly at high Reynolds numbers (Re ~106 ~107) for commercial airplanes. However, small-size unmanned air vehicles (UAV), operating at low Reynolds numbers (Re PIV measurements are conducted at several cross-flow planes for a few different angles of attack (α) . At high angles of attack (7° ~13°) , the winglets with the cant angle of 70° increase the aerodynamic performance, whereas at low angles of attack (2° ~6°) , the wing-tip extension (cant angle of 0°) shows better performances. The velocity fields measured from PIV indicate that, with the winglet, the wing-tip vortex moves away from the wing surface at α =12° , and the downwash motion in the wake behind the trailing edge is decreased, reducing the magnitude of the induced drag. A concept of changing the cant angle during flight is also suggested at this talk. Supported by 2011-0028032.

  1. Reynolds analogy for subcooled surface boiling under forced convection

    International Nuclear Information System (INIS)

    Avdeev, A.A.

    1982-01-01

    For the case of subcooled surface boiling under forced convection the analytic expression of analogy between the heat transfer and carry pulse (Reynolds analogy) is derived. It is concluded that the obtained dependence creates the basis for solution of a series of problems of surface boiling physics. On the basis of the performed analysis the method of coordinate calculation of the origin of intensive vapour generation is developed and the formula for calculation of the broken-off-bubble radius under forced convection is derived [ru

  2. Features of round air jet flowing at low Reynolds numbers

    Science.gov (United States)

    Lemanov, V. V.; Sharov, K. A.; Gorinovich, N. V.

    2018-03-01

    The laminar-turbulent transition in a round jet flowing from a cylindrical channel with the diameter of 3.2 mm was studied experimentally. In experiments, the range of Reynolds numbers determined by the mean-flow velocity was Re = Ud/ν = 700-12000. The measurements were carried out using a PIV system and one-component hot-wire anemometer. The profiles of average velocities and their pulsations in the zone of laminar-turbulent transition were obtained along with axial distributions of longitudinal velocity and pulsations of longitudinal velocity.

  3. Investigating the round air jet dynamics at low Reynolds numbers

    Directory of Open Access Journals (Sweden)

    Lemanov Vadim

    2017-01-01

    Full Text Available The laminar-turbulent transition in a round jet flowing from a cylindrical channel with the diameter of 3.2 mm was studied experimentally. In experiments, the range of Reynolds numbers determined by the mean-flow velocity was Re = Ud/v = 700-12000. The measurements were carried out using a PIV system and one-component hot-wire anemometer. The profiles of average velocities and their pulsations in the zone of laminar-turbulent transition were obtained, as well as axial distributions of longitudinal velocity and pulsations of longitudinal velocity.

  4. Stress in highly demanding IT jobs: transformational leadership moderates the impact of time pressure on exhaustion and work-life balance.

    Science.gov (United States)

    Syrek, Christine J; Apostel, Ella; Antoni, Conny H

    2013-07-01

    The objective of this article is to investigate transformational leadership as a potential moderator of the negative relationship of time pressure to work-life balance and of the positive relationship between time pressure and exhaustion. Recent research regards time pressure as a challenge stressor; while being positively related to motivation and performance, time pressure also increases employee strain and decreases well-being. Building on the Job Demand-Resources model, we hypothesize that transformational leadership moderates the relationships between time pressure and both employees' exhaustion and work-life balance such that both relationships will be weaker when transformational leadership is higher. Of seven information technology organizations in Germany, 262 employees participated in the study. Established scales for time pressure, transformational leadership, work-life balance, and exhaustion were used, all showing good internal consistencies. The results support our assumptions. Specifically, we find that under high transformational leadership the impact of time pressure on exhaustion and work-life balance was less strong. The results of this study suggest that, particularly under high time pressure, transformational leadership is an important factor for both employees' work-life balance and exhaustion. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  5. Fatigue Moderates the Relationship Between Perceived Stress and Suicidal Ideation: Evidence From Two High-Resolution Studies.

    Science.gov (United States)

    Kleiman, Evan M; Turner, Brianna J; Chapman, Alexander L; Nock, Matthew K

    2018-01-01

    Theoretical models of self-harm suggest that high perceived stress and high fatigue (which might affect the ability to cope with stress) may interact to predict the short-term occurrence of suicidal ideation and nonsuicidal self-injury (NSSI). We tested 3 approaches to examining this interaction, each of which provided a different understanding of the specific nature of these associations: comparing each individual's daily stress/fatigue to the entire sample's overall average (i.e., grand-mean centering), comparing each individual's daily perceived stress/fatigue to his or her overall average (i.e., group- or participant-mean centering), and comparing each individual's average perceived stress/fatigue to the sample's overall average (i.e., centering participant means on overall grand mean). In 2 studies, adolescents (n = 30; 574 daily reports, M age = 17.3 years, range = 12-19; 87.6% female) and young adults (n = 60; 698 daily reports; M age = 23.25 years, range = 18-35; 85% female) completed daily measures of perceived stress, fatigue, suicidal ideation, and NSSI. In both samples, the interaction between high daily perceived stress and high daily fatigue predicted greater odds of daily suicidal ideation (but not NSSI). Only the model comparing each individual's daily stress/fatigue to the entire sample's overall average was consistently significant across the two studies. Participants were most likely to experience suicidal ideation on days when both perceived stress and fatigue were elevated relative to the average level experienced across people and time points. Studies should build upon these findings with more in-depth examination of the temporal nature of stability and change in these factors as they relate to sustained suicidal ideation.

  6. High Altitude Headache and Acute Mountain Sickness at Moderate Elevations in a Military Population During Battalion-Level Training Exercises

    Science.gov (United States)

    2012-08-01

    activities falling between 2,400 and 3,300m. Ascent and descent profiles were variable according to the unit to which a given Marine was attached. Because all...for full duty status. Participants had ready access to water and medical care and available interventions against AMS included descent , oxygen, and...Acetazolamide Dosage Comparison for Efficacy (PACE) trial. High Alt Med Biol 2006; 7(1): 17-27. 14. Basnyat B, Gertsch JH, Johnson EW, Castro-Marin F

  7. From high doses of oral rivastigmine to transdermal rivastigmine patches: user experience and satisfaction among caregivers of patients with mild to moderate Alzheimer disease.

    Science.gov (United States)

    Reñé, R; Ricart, J; Hernández, B

    2014-03-01

    Rivastigmine, a treatment for mild to moderate Alzheimer disease (AD), is the first cholinesterase inhibitor to be available in the transdermal format. We aim to describe user experience and satisfaction with the rivastigmine patch, as well as any clinical changes perceived in patients. Observational, cross-sectional, multicentre study with 239 investigators and 1851 informal caregivers of patients with mild to moderate AD. Patients were treated with transdermal rivastigmine patches for ≥ 6 months and had previously received high doses of oral rivastigmine. Mean caregiver age was 59.8±14.4 years and 70.9% were women. They spent 10.0±7.1hours per day providing care and 79.8% lived with the patient. Patch instructions were described as easy to follow by 97.1% of the caregivers and 92.1% of them rated patch application as easy or very easy. The most commonly cited disadvantage was adhesion problems (26.8%). Discontinuation of treatment was due to cutaneous reactions in most cases. Overall, 76.5% of the caregivers were satisfied or very satisfied with transdermal treatment and 77.4% considered that its interference with daily activities was minimal or null. The patch was preferred to oral treatment by 94.3% of caregivers. Clinical Global Impression of Change ratings improved according to 61.3% of the caregivers and 53% of the investigators. Few caregivers reported medication forgetfulness. Most caregivers of patients with mild to moderate AD preferred the transdermal format of rivastigmine to the oral format. Caregivers also reported overall satisfaction, ease of use, and reduced impact on daily activities for transdermal rivastigmine format, in addition to patient improvement compared to their condition under the previous treatment. Copyright © 2012 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  8. A comparison of the health benefits of reduced-exertion high-intensity interval training (REHIT) and moderate-intensity walking in type 2 diabetes patients.

    Science.gov (United States)

    Ruffino, José S; Songsorn, Preeyaphorn; Haggett, Malindi; Edmonds, Daniel; Robinson, Anthony M; Thompson, Dylan; Vollaard, Niels B J

    2017-02-01

    Reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient intervention that can improve aerobic capacity and insulin sensitivity in sedentary individuals. The present study compared the effects of REHIT and moderate-intensity walking on health markers in patients with type 2 diabetes (T2D) in a counter-balanced crossover study. Sixteen men with T2D (mean ± SD age: 55 ± 5 years, body mass index: 30.6 ± 2.8 kg·m -2 , maximal aerobic capacity: 27 ± 4 mL·kg -1 ·min -1 ) completed 8 weeks of REHIT (three 10-min low-intensity cycling sessions/week with two "all-out" 10-20-s sprints) and 8 weeks of moderate-intensity walking (five 30-min sessions/week at an intensity corresponding to 40%-55% of heart-rate reserve), with a 2-month wash-out period between interventions. Before and after each intervention, participants underwent an incremental fitness test, an oral glucose tolerance test (OGTT), a whole-body dual-energy X-ray absorptiometry scan, and continuous glucose monitoring. REHIT was associated with a significantly larger increase in maximal aerobic capacity compared with walking (7% vs. 1%; time × intervention interaction effect: p body composition. We conclude that REHIT is superior to a 5-fold larger volume of moderate-intensity walking in improving aerobic fitness, but similar to walking REHIT is not an effective intervention for improving insulin sensitivity or glycaemic control in T2D patients in the short term.

  9. Lip-reading aids word recognition most in moderate noise: a Bayesian explanation using high-dimensional feature space.

    Science.gov (United States)

    Ma, Wei Ji; Zhou, Xiang; Ross, Lars A; Foxe, John J; Parra, Lucas C

    2009-01-01

    Watching a speaker's facial movements can dramatically enhance our ability to comprehend words, especially in noisy environments. From a general doctrine of combining information from different sensory modalities (the principle of inverse effectiveness), one would expect that the visual signals would be most effective at the highest levels of auditory noise. In contrast, we find, in accord with a recent paper, that visual information improves performance more at intermediate levels of auditory noise than at the highest levels, and we show that a novel visual stimulus containing only temporal information does the same. We present a Bayesian model of optimal cue integration that can explain these conflicts. In this model, words are regarded as points in a multidimensional space and word recognition is a probabilistic inference process. When the dimensionality of the feature space is low, the Bayesian model predicts inverse effectiveness; when the dimensionality is high, the enhancement is maximal at intermediate auditory noise levels. When the auditory and visual stimuli differ slightly in high noise, the model makes a counterintuitive prediction: as sound quality increases, the proportion of reported words corresponding to the visual stimulus should first increase and then decrease. We confirm this prediction in a behavioral experiment. We conclude that auditory-visual speech perception obeys the same notion of optimality previously observed only for simple multisensory stimuli.

  10. Lip-reading aids word recognition most in moderate noise: a Bayesian explanation using high-dimensional feature space.

    Directory of Open Access Journals (Sweden)

    Wei Ji Ma

    Full Text Available Watching a speaker's facial movements can dramatically enhance our ability to comprehend words, especially in noisy environments. From a general doctrine of combining information from different sensory modalities (the principle of inverse effectiveness, one would expect that the visual signals would be most effective at the highest levels of auditory noise. In contrast, we find, in accord with a recent paper, that visual information improves performance more at intermediate levels of auditory noise than at the highest levels, and we show that a novel visual stimulus containing only temporal information does the same. We present a Bayesian model of optimal cue integration that can explain these conflicts. In this model, words are regarded as points in a multidimensional space and word recognition is a probabilistic inference process. When the dimensionality of the feature space is low, the Bayesian model predicts inverse effectiveness; when the dimensionality is high, the enhancement is maximal at intermediate auditory noise levels. When the auditory and visual stimuli differ slightly in high noise, the model makes a counterintuitive prediction: as sound quality increases, the proportion of reported words corresponding to the visual stimulus should first increase and then decrease. We confirm this prediction in a behavioral experiment. We conclude that auditory-visual speech perception obeys the same notion of optimality previously observed only for simple multisensory stimuli.

  11. The source of X-rays and high-charged ions based on moderate power vacuum discharge with laser triggering

    Directory of Open Access Journals (Sweden)

    Alkhimova Mariya A.

    2015-06-01

    Full Text Available The source of X-ray radiation with the energy of quanta that may vary in the range hν = 1÷12 keV was developed for studies in X-ray interaction with matter and modification of solid surfaces. It was based on a vacuum spark discharge with the laser triggering. It was shown in our experiments that there is a possibility to adjust X-ray radiation spectrum by changing the configuration of the electrode system when the energy stored in the capacitor is varied within the range of 1÷17 J. A comprehensive study of X-ray imaging and quanta energy was carried out. These experiments were carried out for the case of both direct and reverse polarity of the voltage on the electrodes. Additionally, ion composition of plasma created in a laser-triggered vacuum discharge was analyzed. Highly charged ions Zn(+21, Cu(+20 and Fe(+18 were observed.

  12. Highly efficient phosphor-converted white organic light-emitting diodes with moderate microcavity and light-recycling filters.

    Science.gov (United States)

    Cho, Sang-Hwan; Oh, Jeong Rok; Park, Hoo Keun; Kim, Hyoung Kun; Lee, Yong-Hee; Lee, Jae-Gab; Do, Young Rag

    2010-01-18

    We demonstrate the combined effects of a microcavity structure and light-recycling filters (LRFs) on the forward electrical efficiency of phosphor-converted white organic light-emitting diodes (pc-WOLEDs). The introduction of a single pair of low- and high-index layers (SiO(2)/TiO(2)) improves the blue emission from blue OLED and the insertion of blue-passing and yellow-reflecting LRFs enhances the forward yellow emission from the YAG:Ce(3+) phosphors layers. The enhancement of the luminous efficacy of the forward white emission is 1.92 times that of a conventional pc-WOLED with color coordinates of (0.34, 0.34) and a correlated color temperature of about 4800 K.

  13. Boundary-Layer Control: In Memory of Bill Reynolds

    Science.gov (United States)

    Kim, John

    2004-11-01

    Professor Bill Reynolds (1933-2004) inspired many students and colleagues with his never-ending curiosity and thought-provoking ideas. Bill's relentless energy, together with his hallmark can-do character and do-it-yourself attitude, led to many seminal contributions to mechanical engineering in general, and fluid mechanics in particular. He has left a lasting impact on many of us, especially for those who had the privilege of working closely with him. Some of my current work on boundary-layer control, the use of neural networks in particular, were inspired by many discussions with Bill. He was among the first to see the potential of control-theoretic approaches for flow control, which has become the main thrust of my current research. Without his continued encouragement, I would not have been deeply involved in this line of research; and perhaps, we would not have seen the current flurry of research activities in applying modern control theories to flow control. In memory of Bill Reynolds, who himself has contributed much to flow control, an analysis of boundary-layer control from a linear system perspective will be presented.

  14. Reynolds number scaling of straining motions in turbulence

    Science.gov (United States)

    Elsinga, Gerrit; Ishihara, T.; Goudar, M. V.; da Silva, C. B.; Hunt, J. C. R.

    2017-11-01

    Strain is an important fluid motion in turbulence as it is associated with the kinetic energy dissipation rate, vorticity stretching, and the dispersion of passive scalars. The present study investigates the scaling of the turbulent straining motions by evaluating the flow in the eigenframe of the local strain-rate tensor. The analysis is based on DNS of homogeneous isotropic turbulence covering a Reynolds number range Reλ = 34.6 - 1131. The resulting flow pattern reveals a shear layer containing tube-like vortices and a dissipation sheet, which both scale on the Kolmogorov length scale, η. The vorticity stretching motions scale on the Taylor length scale, while the flow outside the shear layer scales on the integral length scale. These scaling results are consistent with those in wall-bounded flow, which suggests a quantitative universality between the different flows. The overall coherence length of the vorticity is 120 η in all directions, which is considerably larger than the typical size of individual vortices, and reflects the importance of spatial organization at the small scales. Transitions in flow structure are identified at Reλ 45 and 250. Below these respective Reynolds numbers, the small-scale motions and the vorticity stretching motions appear underdeveloped.

  15. Reynolds number effects on gill pumping mechanics in mayfly nymphs

    Science.gov (United States)

    Sensenig, Andrew; Shultz, Jeffrey; Kiger, Ken

    2006-11-01

    Mayfly nymphs have an entirely aquatic life stage in which they frequently inhabit stagnant water. Nymphs have the capability to generate a ventilation current to compensate for the low oxygen level of the water by beating two linear arrays of plate-like gills that typically line the lateral edge of the abdomen. The characteristic Reynolds number associated with the gill motion changes with animal size, varying over a span of Re = 5 to 100 depending on age and species. The assumption that the system maintains optimal energetic efficiency leads to the prediction that animals transition from rowing to flapping mechanisms with increasing Re, while possibly utilizing a squeeze mechanism to a greater extent at lower Re. To investigate this hypothesis, we capture the motion of the gills through 3D imaging to investigate the effect of Reynolds number on the stroke patterns. PIV is utilized to assess flow rates and viscous dissipation. The effectiveness of the ventilation mechanism at each size has important consequences for the range of oxygen levels, and hence the habitat range, that can be tolerated by that size.

  16. Hydrodynamics of Low Reynolds Respiratory-type Flows

    Science.gov (United States)

    Connor, Erin; True, Aaron; Crimaldi, John

    2017-11-01

    Both aquatic and terrestrial animals inhale surrounding fluid for metabolic and sensory purposes. As organisms inhale and exhale, complex fluid interactions occur both internal and external to the physiological orifice. Using both numerical and experimental approaches, we model an idealized respiratory flow consisting of cyclic inhalation and exhalation through a single cylindrical tube. We investigate the effect of varying Reynolds number (Re) as well as the ratio of the inhalation time to the exhalation time (I:E ratio) for a fixed inhalation volume. The numerical model is used for laminar cases at lower Re, whereas the experimental model permits the study to be extended into higher Reynolds numbers that include transitions to turbulence. We map the spatial distribution of both inhaled and exhaled fluid volumes. By comparing these two maps, we can compute the volume of exhaled fluid that is reingested during the subsequent inhalation. The models of interacting inhalation and exhalation exhibit a rich range of flow behaviors across Re number and I:E ratio. This study builds a foundation for more complex studies of animal respiration that will include more realistic morphologies.

  17. The Role of Separation Bubbles on the Aerodynamic Characteristics of Airfoils, Including Stall and Post-Stall, at Low Reynolds Numbers

    Science.gov (United States)

    Chen, Hsun H.; Cebeci, Tuncer

    2007-01-01

    Airfoils at high Reynolds numbers, in general, have small separation bubbles that are usually confined to the leading edge. Since the Reynolds number is large, the turbulence model for the transition region between the laminar and turbulent flow is not important. Furthermore, the onset of transition occurs either at separation or prior to separation and can be predicted satisfactorily by empirical correlations when the incident angle is small and can be assumed to correspond to laminar separation when the correlations do not apply, i.e., at high incidence angles.

  18. Low to moderate temperature nanolaminate heater

    Science.gov (United States)

    Eckels, J Del [Livermore, CA; Nunes, Peter J [Danville, CA; Simpson, Randall L [Livermore, CA; Hau-Riege, Stefan [Fremont, CA; Walton, Chris [Oakland, CA; Carter, J Chance [Livermore, CA; Reynolds, John G [San Ramon, CA

    2011-01-11

    A low to moderate temperature heat source comprising a high temperature energy source modified to output low to moderate temperatures wherein the high temperature energy source modified to output low to moderate temperatures is positioned between two thin pieces to form a close contact sheath. In one embodiment the high temperature energy source modified to output low to moderate temperatures is a nanolaminate multilayer foil of reactive materials that produces a heating level of less than 200.degree. C.

  19. Drag Measurements over Embedded Cavities in a Low Reynolds Number Couette Flow

    Science.gov (United States)

    Gilmer, Caleb; Lang, Amy; Jones, Robert

    2010-11-01

    Recent research has revealed that thin-walled, embedded cavities in low Reynolds number flow have the potential to reduce the net viscous drag force acting on the surface. This reduction is due to the formation of embedded vortices allowing the outer flow to pass over the surface via a roller bearing effect. It is also hypothesized that the scales found on butterfly wings may act in a similar manner to cause a net increase in flying efficiency. In this experimental study, rectangular embedded cavities were designed as a means of successfully reducing the net drag across surfaces in a low Reynolds number flow. A Couette flow was generated via a rotating conveyor belt immersed in a tank of high viscosity mineral oil above which the plates with embedded cavities were placed. Drag induced on the plate models was measured using a force gauge and compared directly to measurements acquired over a flat plate. Various cavity aspect ratios and gap heights were tested in order to determine the conditions under which the greatest drag reductions occurred.

  20. The FX/90: A proposal in response to a low Reynolds Number station keeping mission

    Science.gov (United States)

    Wirthman, David; Palmer, Julie; Gleixner, Aaron; Russell, Scott; Nevala, Tom; Nosek, Mark

    1990-01-01

    The FX/90 is a remotely piloted vehicle designed to fly at Reynolds numbers below 2 x 10 to the 5th power. Several applications exist for this type of flight, such as low altitude flight of very small aircraft. The design presented here allows investigation into the unique problems involved in low Reynolds number flight, which will, in turn, further understanding of this flight regime. The aircraft will operate in a steady flight environment, free from significant atmospheric turbulence and weather effects. The F-90 has a 39 in. fuselage which is constructed of balsa and plywood. The landing gear for the aircraft is a detachable carriage on which the aircraft rests. The aerodynamic planform is a rectangular wing (no taper or sweep) with a chord of 9 in., a wingspan of 72 in., and is constructed entirely out of styrofoam. The propulsion system is a puller configuration mounted on the front of the fuselage. It consists of an Astro 05 engine and a 10-6 two bladed propeller. Control of the aircraft is accomplished through the use of two movable control surfaces: elevators for pitch control, and a rudder for yaw control. The aircraft is soundly constructed, highly maneuverable, and adequately powered. Furthermore, the investigation into alternative technologies, most notably the styrofoam wing and the detachable landing gear, holds promise to improve the performance of the aircraft.

  1. Steady finite-Reynolds-number flows in three-dimensional collapsible tubes

    Science.gov (United States)

    Hazel, Andrew L.; Heil, Matthias

    2003-07-01

    A fully coupled finite-element method is used to investigate the steady flow of a viscous fluid through a thin-walled elastic tube mounted between two rigid tubes. The steady three-dimensional Navier Stokes equations are solved simultaneously with the equations of geometrically nonlinear Kirchhoff Love shell theory. If the transmural (internal minus external) pressure acting on the tube is sufficiently negative then the tube buckles non-axisymmetrically and the subsequent large deformations lead to a strong interaction between the fluid and solid mechanics. The main effect of fluid inertia on the macroscopic behaviour of the system is due to the Bernoulli effect, which induces an additional local pressure drop when the tube buckles and its cross-sectional area is reduced. Thus, the tube collapses more strongly than it would in the absence of fluid inertia. Typical tube shapes and flow fields are presented. In strongly collapsed tubes, at finite values of the Reynolds number, two ’jets‘ develop downstream of the region of strongest collapse and persist for considerable axial distances. For sufficiently high values of the Reynolds number, these jets impact upon the sidewalls and spread azimuthally. The consequent azimuthal transport of momentum dramatically changes the axial velocity profiles, which become approximately uTheta-shaped when the flow enters the rigid downstream pipe. Further convection of momentum causes the development of a ring-shaped velocity profile before the ultimate return to a parabolic profile far downstream.

  2. Reynolds number effect on airfoil wake structures under pitching and heaving motion

    Science.gov (United States)

    Kim, Kyung Chun; Karbasian, Hamidreza; ExpTENsys Team

    2017-11-01

    Detached Eddy Simulation (DES) and particle image velocimetry (PIV) measurements were performed to investigate the wake flow characteristics of an airfoil under pitching and heaving motion. A NACA0012 airfoil was selected for the numerical simulation and experiments were carried out in a wind tunnel and a water tunnel at Reynolds number of 15,000 and 90,000, respectively. The airfoil oscillated around an axis located 1/4 distance from the leading edge chord. Two different angles of attack, 20° and 30°, were selected with +/-10° maximum amplitude of oscillation. In order to extract the coherent flow structures from time-resolved PIV data, proper orthogonal decomposition (POD) analysis was performed on 1,000 instantaneous realisations for each condition using the method of snapshots. Vorticity contour and velocity profiles for both PIV and DES results are in good agreement for pitching and heaving motion. At high Reynolds number, 3D stream-wise vortices appeared after generating span-wise vortices. The higher maximum angle of attack allows the leading edge vortex to grow stronger and that the angle of attack appears to be more important in influencing the growth of the leading edge vortex structure than the reduced frequency. National Research Foundation of Korea (No. 2011-0030013).

  3. Introducing ultrasonic falling film evaporator for moderate temperature evaporation enhancement.

    Science.gov (United States)

    Dehbani, Maryam; Rahimi, Masoud

    2018-04-01

    In the present study, Ultrasonic Falling Film (USFF), as a novel technique has been proposed to increase the evaporation rate of moderate temperature liquid film. It is a proper method for some applications which cannot be performed at high temperature, such as foodstuff industry, due to their sensitivity to high temperatures. Evaporation rate of sodium chloride solution from an USFF on an inclined flat plate compared to that for Falling Film without ultrasonic irradiation (FF) at various temperatures was investigated. The results revealed that produced cavitation bubbles have different effects on evaporation rate at different temperatures. At lower temperatures, size fluctuation and collapse of bubbles and in consequence induced physical effects of cavitation bubbles resulted in more turbulency and evaporation rate enhancement. At higher temperatures, the behavior was different. Numerous created bubbles joined together and cover the plate surface, so not only decreased the ultrasound vibrations but also reduced the evaporation rate in comparison with FF. The highest evaporation rate enhancement of 353% was obtained at 40 °C at the lowest Reynolds number of 250. In addition, the results reveal that at temperature of 40 °C, USFF has the highest efficiency compared to FF. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Production and Characterization of Alkaline Protease from a High Yielding and Moderately Halophilic Strain of SD11 Marine Bacteria

    Directory of Open Access Journals (Sweden)

    Hongxia Cui

    2015-01-01

    Full Text Available A marine bacterium SD11, which was isolated from sea muds (Geziwo Qinhuangdao Sea area, China, was used to produce thermostable alkaline serine nonmetal protease in the skim milk agar plate medium with 10% NaCl. The optimal temperature about the manufacture of the extracellular protease was ~60°C. The crude enzyme was stable at 20–50°C. The activity was retained to 60% and 45% after heating for 1 h at 60 and 70°C, respectively. The protease was highly active in a wide pH scope (8.0–10.0 and maximum protease activity exhibited at pH 10.0. The activity was restrained by phenylmethylsulfonyl fluoride (PMSF but mildly increased (~107% in the presence of ethylenediaminetetraacetic acid (EDTA, indicating that the production contains serine-protease(s and nonmetal protease(s. Moreover, the crude alkaline protease was active with the 5 mM Ca2+, Mn2+, Zn2+, Cu2+, Na+, and K+ that existed separately. In addition, the protease showed superduper stability when exposed to an anionic surfactant (5 mM SDS, an oxidizing agent (1% H2O2, and several organic solvents (methanol, isopropanol, and acetone. These results suggest that the marine bacterium SD11 is significant in the industry from the prospects of its ability to produce thermally stable alkaline protease.

  5. Effects of moderate and high rates of biochar and compost on grapevine growth in a greenhouse experiment

    Directory of Open Access Journals (Sweden)

    Arianna Bozzolo

    2017-03-01

    Full Text Available Biochar is used as soil amendment and enhancer of plant growth, but the mechanisms involved in grapevine are not understood. In this study, the short-term effects of amendments were evaluated in a trial combining three substrates (biochar, compost, peat-based media with three doses (30, 70, 100% along a time sequence on 1-year-old bare root cuttings of grapevine. Amendments were analyzed for elemental composition. Soil pH, electrical conductivity (EC, chlorophyll (CHL, flavonoids (FL, anthocyans (ANT and nitrogen balance index (NBI were measured.Biochar differed from other amendments for stable C structures, where nutrients and lignin residues were high in compost. Biochar increased soil pH, whereas biochar plus compost mixture augmented EC. The amended plants had detrimental effects on root, true and lateral leaves. Nevertheless, at the lowest rate biochar increased the primary shoot and total scion to root biomass ratio. Among biochemicals, ANT and NBI were mostly affected by biochar, while compost gave only slight increments. Thus, although biochar rate was not adequate for the shedding in open field our results suggest that biochar might be useful in nursery when used at low dosages.

  6. Gradual crossover in molecular organization of stable liquid H2O at moderately high pressure and temperature

    DEFF Research Database (Denmark)

    Koga, Yoshikata; Westh, Peter; Yoshida, Koh

    2014-01-01

    temperature. The extrapolated temperature to zero p seems to be about 70 – 80 °C for points X and 90 – 110 °C for Y. Furthermore, the mid-points of X and Y seem to extrapolate to the triple point of liquid, ice Ih and ice III. Recalling that the zero x Gly extrapolation of point X and Y for binary aqueous...... of the step named point X and its end point Y. In analogy with another third and fourth derivative pair in binary aqueous solutions of glycerol, dα p /dx Gly and d2 α p /dx Gly 2, at 0.1 MPa (α p is the thermal expansivity and x Gly the mole fraction of solute glycerol) in our recent publication [J. Solution...... Chem. 43, 663-674 (2014); DOI:10.1007/s10953-013-0122-7], we argue that there is a gradual crossover in the molecular organization of pure H2O from a low to a high p-regions starting at point X and ending at Y at a fixed T. The crossover takes place gradually spanning for about 100 MPa at a fixed...

  7. Similar Anti-Inflammatory Acute Responses from Moderate-Intensity Continuous and High-Intensity Intermittent Exercise

    Directory of Open Access Journals (Sweden)

    Carolina Cabral-Santos, José Gerosa-Neto, Daniela Sayuri Inoue, Valéria Leme Gonçalves Panissa, Luís Alberto Gobbo, Alessandro Moura Zagatto, Eduardo Zapaterra Campos, Fábio Santos Lira

    2015-12-01

    Full Text Available The purpose of this study was to compare the effect of high-intensity intermittent exercise (HIIE versus volume matched steady state exercise (SSE on inflammatory and metabolic responses. Eight physically active male subjects completed two experimental sessions, a 5-km run on a treadmill either continuously (70% vVO2max or intermittently (1:1 min at vVO2max. Blood samples were collected at rest, immediately, 30 and 60 minutes after the exercise session. Blood was analyzed for glucose, non-ester fatty acid (NEFA, uric acid, lactate, cortisol, and cytokines (IL-6, IL-10 and TNF-α levels. The lactate levels exhibited higher values immediately post-exercise than at rest (HIIE 1.34 ± 0.24 to 7.11 ± 2.85, and SSE 1.35 ± 0.14 to 4.06±1.60 mmol·L-1, p 0.05. Cortisol, IL-6, IL-10 and TNF-α levels showed time-dependent changes under the different conditions (p < 0.05, however, the area under the curve of TNF-α in the SSE were higher than HIIE (p < 0.05, and the area under the curve of IL-6 in the HIIE showed higher values than SSE (p < 0.05. In addition, both exercise conditions promote increased IL-10 levels and IL-10/TNF-α ratio (p < 0.05. In conclusion, our results demonstrated that both exercise protocols, when volume is matched, promote similar inflammatory responses, leading to an anti-inflammatory status; however, the metabolic responses are different.

  8. Chloroquine efficacy for Plasmodium vivax in Myanmar in populations with high genetic diversity and moderate parasite gene flow.

    Science.gov (United States)

    Htun, Myo Win; Mon, Nan Cho Nwe; Aye, Khin Myo; Hlaing, Chan Myae; Kyaw, Myat Phone; Handayuni, Irene; Trimarsanto, Hidayat; Bustos, Dorina; Ringwald, Pascal; Price, Ric N; Auburn, Sarah; Thriemer, Kamala

    2017-07-10

    Plasmodium vivax malaria remains a major public health burden in Myanmar. Resistance to chloroquine (CQ), the first-line treatment for P. vivax, has been reported in the country and has potential to undermine local control efforts. Patients over 6 years of age with uncomplicated P. vivax mono-infection were enrolled into clinical efficacy studies in Myawaddy in 2014 and Kawthoung in 2012. Study participants received a standard dose of CQ (25 mg/kg over 3 days) followed by weekly review until day 28. Pvmdr1 copy number (CN) and microsatellite diversity were assessed on samples from the patients enrolled in the clinical study and additional cross-sectional surveys undertaken in Myawaddy and Shwegyin in 2012. A total of 85 patients were enrolled in the CQ clinical studies, 25 in Myawaddy and 60 in Kawthoung. One patient in Myawaddy (1.2%) had an early treatment failure and two patients (2.3%) in Kawthoung presented with late treatment failures on day 28. The day 28 efficacy was 92.0% (95% CI 71.6-97.9) in Myawaddy and 98.3% (95% CI 88.7-99.8) in Kawthoung. By day 2, 92.2% (23/25) in Myawaddy and 85.0% (51/60) in Kawthoung were aparasitaemic. Genotyping and pvmdr1 CN assessment was undertaken on 43, 52 and 46 clinical isolates from Myawaddy, Kawthoung and Shwegyin respectively. Pvmdr1 amplification was observed in 3.2% (1/31) of isolates in Myawaddy, 0% (0/49) in Kawthoung and 2.5% (1/40) in Shwegyin. Diversity was high in all sites (H E 0.855-0.876), with low inter-population differentiation (F ST 0.016-0.026, P Myanmar, particularly given the potential connectivity between parasite population at different sites.

  9. The effects of high intensity exercise during pulmonary rehabilitation on ventilatory parameters in people with moderate to severe stable COPD: a systematic review

    Directory of Open Access Journals (Sweden)

    Osterling K

    2014-10-01

    Full Text Available Kristin Osterling,1 Kimbly MacFadyen,1 Robert Gilbert,2 Gail Dechman1 1School of Physiotherapy, 2School of Health Sciences, Dalhousie University, Halifax, NS, Canada Objective: The objective of this systematic review was to determine whether people with moderate to severe COPD who are participating in pulmonary rehabilitation and exercising at high intensity demonstrate the changes in ventilatory parameters that are associated with decreased dyspnea. Data sources: The authors searched EMBASE, The Cochrane Library, and CINAHL databases up to December 2013 for relevant randomized control trials, systematic reviews, and observational studies. References of identified studies were also screened. Study selection: Studies conducted in a pulmonary rehabilitation setting that included education and exercise were included. Symptom-limited, graded exercise testing that measured tidal volume, respiratory rate, minute ventilation, and inspiratory capacity was required. The studies that contained these keywords in the title or the abstract were selected for further evaluation of the text. Disagreements between reviewers were resolved by consensus. Four studies met these inclusion criteria. Data extraction: Quality assessment and data extraction were performed independently by two reviewers. Risk of bias and quality was assessed according to the Cochrane Handbook for Systematic Reviews of Interventions. Data synthesis: Participants in three studies trained at high intensity (70%–80% maximum workload, demonstrating statistically significant changes in tidal volume and respiratory rate. One study did not demonstrate positive ventilatory benefits; however, participants may not have met the desired training intensity. Two studies reported improvement in dyspnea at submaximal exercise intensities. One study noted an increased maximum workload with no significant change in dyspnea at peak exercise. Conclusion: People with moderate to severe, stable COPD were able

  10. Pharmacokinetics, safety, and efficacy of APF530 (extended-release granisetron in patients receiving moderately or highly emetogenic chemotherapy: results of two Phase II trials

    Directory of Open Access Journals (Sweden)

    Gabrail N

    2015-03-01

    Full Text Available Nashat Gabrail,1 Ronald Yanagihara,2 Marek Spaczyński,3 William Cooper,4 Erin O'Boyle,5 Carrie Smith,1 Ralph Boccia6 1Gabrail Cancer Center, Canton, OH, USA; 2St Louise Regional Hospital, Gilroy, CA, USA; 3Department of Gynecology, Obstetrics and Gynecologic Oncology, University of Medical Sciences, Poznan, Poland; 4TFS International, Flemington, NJ, USA; 5FibroGen, Inc., San Francisco, CA, USA; 6Center for Cancer and Blood Disorders, Bethesda, MD, USA Background: Despite advances with new therapies, a significant proportion of patients (>30% suffer delayed-onset chemotherapy-induced nausea and vomiting (CINV despite use of antiemetics. APF530 is a sustained-release subcutaneous (SC formulation of granisetron for preventing CINV. APF530 pharmacokinetics, safety, and efficacy were studied in two open-label, single-dose Phase II trials (C2005-01 and C2007-01, respectively in patients receiving moderately emetogenic chemotherapy or highly emetogenic chemotherapy. Methods: In C2005-01, 45 patients received APF530 250, 500, or 750 mg SC (granisetron 5, 10, or 15 mg, respectively. In C2007-01, 35 patients were randomized to APF530 250 or 500 mg SC. Injections were given 30 to 60 minutes before single-day moderately emetogenic chemotherapy or highly emetogenic chemotherapy. Plasma granisetron was measured from predose to 168 hours after study drug administration. Safety and efficacy were also evaluated. Results: APF530 pharmacokinetics were dose proportional, with slow absorption and elimination of granisetron after a single SC dose. Median time to maximum plasma concentration and half-life were similar for APF530 250 and 500 mg in both trials, with no differences between the groups receiving moderately and highly emetogenic chemotherapy. Exposure to granisetron was maintained at a therapeutic level over the delayed-onset phase, at least 168 hours. Adverse events in both trials were as expected for granisetron; injection site reactions (eg, erythema

  11. Effects of Dietary Nitrate Supplementation on Physiological Responses, Cognitive Function, and Exercise Performance at Moderate and Very-High Simulated Altitude

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    Oliver M. Shannon

    2017-06-01

    Full Text Available Purpose: Nitric oxide (NO bioavailability is reduced during acute altitude exposure, contributing toward the decline in physiological and cognitive function in this environment. This study evaluated the effects of nitrate (NO3− supplementation on NO bioavailability, physiological and cognitive function, and exercise performance at moderate and very-high simulated altitude.Methods:Ten males (mean (SD: V˙O2max: 60.9 (10.1 ml·kg−1·min−1 rested and performed exercise twice at moderate (~14.0% O2; ~3,000 m and twice at very-high (~11.7% O2; ~4,300 m simulated altitude. Participants ingested either 140 ml concentrated NO3−-rich (BRJ; ~12.5 mmol NO3− or NO3−-deplete (PLA; 0.01 mmol NO3− beetroot juice 2 h before each trial. Participants rested for 45 min in normobaric hypoxia prior to completing an exercise task. Exercise comprised a 45 min walk at 30% V˙O2max and a 3 km time-trial (TT, both conducted on a treadmill at a 10% gradient whilst carrying a 10 kg backpack to simulate altitude hiking. Plasma nitrite concentration ([NO2−], peripheral oxygen saturation (SpO2, pulmonary oxygen uptake (V˙O2, muscle and cerebral oxygenation, and cognitive function were measured throughout.Results: Pre-exercise plasma [NO2−] was significantly elevated in BRJ compared with PLA (p = 0.001. Pulmonary V˙O2 was reduced (p = 0.020, and SpO2 was elevated (p = 0.005 during steady-state exercise in BRJ compared with PLA, with similar effects at both altitudes. BRJ supplementation enhanced 3 km TT performance relative to PLA by 3.8% [1,653.9 (261.3 vs. 1718.7 (213.0 s] and 4.2% [1,809.8 (262.0 vs. 1,889.1 (203.9 s] at 3,000 and 4,300 m, respectively (p = 0.019. Oxygenation of the gastrocnemius was elevated during the TT consequent to BRJ (p = 0.011. The number of false alarms during the Rapid Visual Information Processing Task tended to be lower with BRJ compared with PLA prior to altitude exposure (p = 0.056. Performance in all other cognitive tasks

  12. Greater effects of high- compared with moderate-intensity interval training on cardio-metabolic variables, blood leptin concentration and ratings of perceived exertion in obese adolescent females

    Directory of Open Access Journals (Sweden)

    G Racil

    2016-04-01

    Full Text Available This study examined the effects of high- vs. moderate-intensity interval training on cardiovascular fitness, leptin levels and ratings of perceived exertion (RPE in obese female adolescents. Forty-seven participants were randomly assigned to one of three groups receiving either a 1:1 ratio of 15 s of effort comprising moderate-intensity interval training (MIIT at 80% maximal aerobic speed: MAS or high-intensity interval training (HIIT at 100% MAS, with matched 15 s recovery at 50% MAS, thrice weekly, or a no-training control group. The HIIT and MIIT groups showed improved (p˂0.05 body mass (BM, BMI Z-score, and percentage of body fat (%BF. Only the HIIT group showed decreased waist circumference (WC (p=0.017. The effect of exercise on maximal oxygen uptake (VO2max was significant (p=0.019, ES=0.48 and p=0.010, ES=0.57, HIIT and MIIT, respectively. The decrease of rate-pressure product (RPP (p<0.05, ES=0.53 and ES=0.46, HIIT and MIIT, respectively followed the positive changes in resting heart rate and blood pressures. Blood glucose, insulin level and the homeostasis model assessment index for insulin decreased (p<0.05 in both training groups. Significant decreases occurred in blood leptin (p=0.021, ES=0.67 and p=0.011, ES=0.73 and in RPE (p=0.001, ES=0.76 and p=0.017, ES=0.57 in HIIT and MIIT, respectively. In the post-intervention period, blood leptin was strongly associated with %BF (p<0.001 and VO2max (p<0.01 in the HIIT and MIIT groups, respectively, while RPE was strongly associated with BM (p<0.01 in the HIIT group. The results suggest that high-intensity interval training may produce more positive effects on health determinants in comparison with the same training mode at a moderate intensity.

  13. Gradual crossover in molecular organization of stable liquid H2O at moderately high pressure and temperature

    Directory of Open Access Journals (Sweden)

    Yoshikata Koga

    2014-09-01

    Full Text Available Using the literature raw data of the speed of sound and the specific volume, the isothermal compressibility, κT, a second derivative thermodynamic quantity of G, was evaluated for liquid H2O in the pressure range up to 350 MPa and the temperature to 50 ºC. We then obtained its pressure derivative, dκT/dp, a third derivative numerically without using a fitting function to the κT data. On taking yet another p-derivative at a fixed T graphically without resorting to any fitting function, the resulting d2κT/dp2, a fourth derivative, showed a weak but clear step anomaly, with the onset of the step named point X and its end point Y. In analogy with another third and fourth derivative pair in binary aqueous solutions of glycerol, dαp/dxGly and d2αp/dxGly2, at 0.1 MPa (αp is the thermal expansivity and xGly the mole fraction of solute glycerol in our recent publication [J. Solution Chem. 43, 663-674 (2014; DOI:10.1007/s10953-013-0122-7], we argue that there is a gradual crossover in the molecular organization of pure H2O from a low to a high p-regions starting at point X and ending at Y at a fixed T. The crossover takes place gradually spanning for about 100 MPa at a fixed temperature. The extrapolated temperature to zero p seems to be about 70 – 80 °C for points X and 90 – 110 °C for Y. Furthermore, the mid-points of X and Y seem to extrapolate to the triple point of liquid, ice Ih and ice III. Recalling that the zero xGly extrapolation of point X and Y for binary aqueous glycerol at 0.1 MPa gives about the same T values respectively, we suggest that at zero pressure the region below about 70 °C the hydrogen bond network is bond-percolated, while above about 90 ºC there is no hydrogen bond network. Implication of these findings is discussed.

  14. Short-Term High- and Moderate-Intensity Training Modifies Inflammatory and Metabolic Factors in Response to Acute Exercise

    Directory of Open Access Journals (Sweden)

    Fabio Santos Lira

    2017-10-01

    Full Text Available Purpose: To compare the acute and chronic effects of high intensity intermittent training (HIIT and steady state training (SST on the metabolic profile and inflammatory response in physically active men.Methods: Thirty recreationally active men were randomly allocated to a control group (n = 10, HIIT group (n = 10, or SST group (n = 10. For 5 weeks, three times per week, subjects performed HIIT (5 km 1-min at 100% of maximal aerobic speed interspersed by 1-min passive recovery or SST (5 km at 70% of maximal aerobic speed while the control group did not perform training. Blood samples were collected at fasting (~12 h, pre-exercise, immediately post, and 60 min post-acute exercise session (pre- and post-5 weeks training. Blood samples were analyzed for glucose, non-ester fatty acid (NEFA, and cytokine (IL-6, IL-10, and TNF-α levels through a three-way analysis (group, period, and moment of measurement with repeated measures in the second and third factors.Results: The results showed an effect of moment of measurement (acute session with greater values to TNF-α and glucose immediately post the exercise when compared to pre exercise session, independently of group or training period. For IL-6 there was an interaction effect for group and moment of measurement (acute session the increase occurred immediately post-exercise session and post-60 min in the HIIT group while in the SST the increase was observed only 60 min post, independently of training period. For IL-10, there was an interaction for training period (pre- and post-training and moment of measurement (acute session, in which in pre-training, pre-exercise values were lower than immediately and 60 min post-exercise, in post-training period pre-exercise values were lower than immediately post-exercise and immediately post-exercise lower than 60 min post, it was also observed that values immediately post-exercise were lower pre- than post-training, being all results independently of intensity

  15. Near wake Reynolds-averaged Navier–Stokes predictions of the wake behind the MEXICO rotor in axial and yawed flow conditions

    DEFF Research Database (Denmark)

    Sørensen, Niels N.; Bechmann, Andreas; Réthoré, Pierre-Elouan

    2014-01-01

    In the present paper, Reynolds-averaged Navier–Stokes predictions of the flow field around the MEXICO rotor in yawed conditions are compared with measurements. The paper illustrates the high degree of qualitative and quantitative agreement that can be obtained for this highly unsteady flow...

  16. Does the flatness of the velocity derivative blow up at a finite Reynolds number?

    International Nuclear Information System (INIS)

    Sreenivasan, K.R.; Bershadskii, A.

    2006-12-01

    A tentative suggestion is made that the flatness of the velocity derivative could reach an infinite value at finite (though very large) Reynolds number, with possible implications for the singularities of the Navier-Stokes equations. A direct test of this suggestion requires measurements at Reynolds numbers presently outside the experimental capacity, so an alternative suggestion that can be tested at accessible Reynolds numbers is also made. (author)

  17. Model Experiments with Low Reynolds Number Effects in a Ventilated Room

    DEFF Research Database (Denmark)

    Nielsen, Peter V.; Filholm, Claus; Topp, Claus

    the isothermal low Reynolds number flow from a slot inlet in the end wall of the room. The experiments are made on the scale of 1 to 5. Measurements indicate a low Reynolds number effect in the wall jet flow. The virtual origin of the wall jet moves forward in front of the opening at a small Reynolds number......, an effect that is also known from measurements on free jets. The growth rate of the jet, or the length scale, increases and the velocity decay factor decreases at small Reynolds numbers....

  18. Management of chemotherapy-induced nausea and vomiting in patients receiving multiple-day highly or moderately emetogenic chemotherapy: role of transdermal granisetron.

    Science.gov (United States)

    Coluzzi, Flaminia; Mattia, Consalvo

    2016-08-01

    Granisetron transdermal delivery system (GTDS) is the first 5-HT3 drug to be transdermally delivered and represents a convenient alternative to oral and intravenous antiemetics for the treatment of chemotherapy-induced nausea and vomiting. GTDS is effective and well tolerated in patients receiving multiple-day moderate-to-highly emetogenic chemotherapy. In this setting noninferiority studies showed similar efficacy when GTDS was compared with intravenous and oral granisetron and intravenous palonosetron. GTDS has shown good cardiovascular safety; however, special caution is needed in patients at risk for developing excessive QTc interval prolongation and arrhythmias. So far, GTDS has been investigated for intravenous prevention in comparison with granisetron and palonosetron; however, further prospects open the route to future clinical investigations.

  19. Internet-delivered cognitive behavioural therapy for adults with mild to moderate depression and high cardiovascular disease risks: a randomised attention-controlled trial.

    Directory of Open Access Journals (Sweden)

    Nicholas Glozier

    Full Text Available BACKGROUND AND AIM: Mild to moderate depression is common in those with cardiovascular disease and undertreated. We aimed to evaluate the effectiveness of internet-delivered Cognitive Behaviour Therapy (iCBT on depressive symptom severity and adherence to medical advice and lifestyle interventions in adults with mild to moderate depression and high cardiovascular disease (CVD risks. METHODS: Randomised double-blind, 12 week attention-controlled trial comparing an iCBT programme (E-couch with an internet-delivered attention control health information package (HealthWatch, n = 282. The primary outcome was depression symptom level on the nine-item Patient Health Questionnaire (PHQ-9 (trial registration: ACTRN12610000085077. RESULTS: 487/562 (88% participants completed the endpoint assessment. 383/562 (70% were currently treated for cardiovascular disease and 314/562 (56% had at least one other comorbid condition. In ITT analysis of 562 participants iCBT produced a greater decline in the mean PHQ-9 score compared to the attention control of 1.06 (95% CI: 0.23-1.89 points, with differences between the two arms increasing over the intervention period (time by treatment effect interaction p = .012. There were also larger improvements in adherence (2.16 points; 95% CI: 0.33-3.99, reductions in anxiety (0.96 points; 95% CI: 0.19-1.73, and a greater proportion engaging in beneficial physical activity (Odds Ratio 1.91, 95%CI: 1.01-3.61 in the iCBT participants but no effect upon disability, or walking time/day. There were no withdrawals due to study related adverse events. CONCLUSIONS: In people with mild to moderate depression and high levels of CVD risk factors, a freely accessible iCBT programme (http://www.ecouch.anu.edu.au produced a small, but robust, improvement in depressive symptoms, adherence and some health behaviours. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry ACTRN12610000085077.

  20. Nitrogen utilization, preweaning nutrient digestibility, and growth effects of Holstein dairy calves fed 2 amounts of a moderately high protein or conventional milk replacer.

    Science.gov (United States)

    Chapman, C E; Hill, T M; Elder, D R; Erickson, P S

    2017-01-01

    Studies have shown that calves fed milk replacers (MR) with crude protein (CP) concentrations greater than 20%, as typically found in conventional MR, have higher dry matter intakes (DMI) and greater average daily gains (ADG) but consume less starter, which can lead to stress during weaning and reduced rumen development. The greater amount of CP being fed to preweaned calves may alter their nitrogen (N) balance, and excess N may be excreted in the urine. The objective of this study was to determine N utilization in preweaned calves fed diets varying in the amount of CP and MR fed. This study used 24 newborn dairy heifer calves blocked by birth and randomly assigned to 1 of 3 treatments: (1) 446g dry matter (DM) of a conventional MR (CON; 20% CP, 20% fat), (2) 669g DM of a moderately high protein MR (moderate; MOD; 26% CP, 18% fat), or (3) 892g DM of a moderately high protein MR (aggressive; AGG; 26% CP, 18% fat). All calves had ad libitum access to starter and water. Both MR and starter were medicated with decoquinate. During weaning (d 43-49), the morning MR feeding ceased. On d 50, all MR feedings ended; however, starter and water intakes were continuously recorded until d 56. At 5wk of age, urine was collected using urinary catheters for 3d and chromium oxide was administered by bolus at 2g/d for 7d to estimate N efficiency. Calves fed MOD and AGG had similar starter intakes, feed efficiencies, and ADG, with the combined treatments having reduced starter intakes (258 vs. 537g/d), greater ADG (674 vs. 422g/d), and improved feed efficiency (0.57 vs. 0.45 gain:feed) compared with CON calves preweaning. However, DMI and water intake were similar across all treatments. Results from the N utilization phase showed that MOD and AGG treatments had similar but lower N efficiency compared with CON calves (45.5 vs. 52.7%). This could be due to MOD- and AGG-fed calves having greater urine volume and thereby, greater combined urine N output compared with CON calves (17.6 vs