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R G Cooper - One of the best experts on this subject based on the ideXlab platform.

  • between days reliability of electromyographic measures of paraspinal muscle fatigue at 40 50 and 60 levels of maximal voluntary contractile force
    Clinical Rehabilitation, 2002
    Co-Authors: Frances Arnall, George A Koumantakis, Jacqueline Oldham, R G Cooper
    Abstract:

    Objective: To ascertain which percentage of maximal voluntary contractile force of the paraspinal muscles, when tested in a functional position, is most reliable for assessing electromyographic (EMG) fatigue changes.Subjects: Ten healthy volunteers with no history of low back pain (six males).Main outcome measures: The surface EMG signal during 60-second isometric contractions of the paraspinal muscles at 40, 50 and 60% levels of maximal voluntary contractile force was captured and analysed. Each contraction level was assessed on two occasions, at least three days apart. The initial median frequency, the decline in median frequency slope and the increase in root Mean Square Values were assessed for between-days reliability, using intraclass correlation coefficients (ICCs) and standard errors of measurements (SEM). Normalized median frequency and root Mean Square Values were also assessed.Results: At 40% of maximal voluntary contraction, little or no EMG fatigue changes occurred in any of the observed para...

Peisheng Zhang - One of the best experts on this subject based on the ideXlab platform.

  • energy harvesting ride comfort and road handling of regenerative vehicle suspensions
    Journal of Vibration and Acoustics, 2013
    Co-Authors: Peisheng Zhang
    Abstract:

    This paper presents a comprehensive assessment of the power that is available for harvesting in the vehicle suspension system and the tradeoff among energy harvesting, ride comfort, and road handing with analysis, simulations, and experiments. The excitation from road irregularity is modeled as a stationary random process with road roughness suggested in the ISO standard. The concept of system H2 norm is used to obtain the Mean value of power generation and the root Mean Square Values of vehicle body acceleration (ride quality) and dynamic tire-ground contact force (road handling). For a quarter car model, an analytical solution of the Mean power is obtained. The influence of road roughness, vehicle speed, suspension stiffness, shock absorber damping, tire stiffness, and the wheel and chasses masses to the vehicle performances and harvestable power are studied. Experiments are carried out to verify the theoretical analysis. The results suggest that road roughness, tire stiffness, and vehicle driving speed have great influence on the harvesting power potential, where the suspension stiffness, absorber damping, and vehicle masses are insensitive. At 60 mph on good and average roads, 100–400 W average power is available in the suspensions of a middle-sized vehicle.

  • energy harvesting ride comfort and road handling of regenerative vehicle suspensions
    ASME 2011 Dynamic Systems and Control Conference and Bath ASME Symposium on Fluid Power and Motion Control Volume 2, 2011
    Co-Authors: Peisheng Zhang
    Abstract:

    This paper presents a comprehensive assessment of the power that is available for harvesting in the vehicle suspension system and the tradeoff among energy harvesting, ride comfort, and road handing with analysis, simulations and experiments. The excitation from road irregularity is modeled as a stationary random process with road roughness suggested in the ISO standard. The concept of system H2 norm is used to obtain Mean value of power generation and the root Mean Square Values of vehicle body acceleration (ride quality) and dynamic tire-ground contact force (road handling). For a quarter car model, analytical solution of the Mean power is obtained. The influence of road roughness, vehicle speed, suspension stiffness, shock absorber damping, tire stiffness, wheel and chasses masses to the vehicle performances and harvestable power are studied. Experiments are carried out to verify the theoretical analysis. The results suggest that road roughness, tire stiffness, and vehicle driving speed have great influence to the harvesting power potential, where the suspension stiffness, absorber damping, vehicle masses are insensitive. At 60mph on good and average roads 100–400 watts average power is available in the suspensions of a middle-size vehicle.Copyright © 2011 by ASME

Thomas Brandt - One of the best experts on this subject based on the ideXlab platform.

  • increased body sway at 3 5 8 hz in patients with phobic postural vertigo
    Neuroscience Letters, 1999
    Co-Authors: S Krafczyk, Veronika Schlamp, Marianne Dieterich, Peter Haberhauer, Thomas Brandt
    Abstract:

    Abstract Postural sway during upright stance was analyzed in 12 patients with phobic postural vertigo (PPV) and in 12 age-matched healthy volunteers. Recordings were made under different conditions (with the eyes open or closed): when standing on a foam rubber pad with the head upright, turned 30 degrees to the right or left, or during 1 Hz horizontal head oscillations. Sway analysis included calculation of sway path, of root Mean Square Values of sway and of the power spectrum of sway in fore/aft and lateral directions. There was a significant increase in sway activity in the 3.53–8 Hz frequency band in patients with PPV. This did not impair objective postural stability. Increase in higher frequency sway activity may simply reflect a change in postural strategy rather than a sensorimotor dysfunction. The patients' conscious control of stance may augment co-activation of anti-gravity muscles, a strategy applied by normal subjects when performing demanding balancing tasks.

Laszlo Baranyi - One of the best experts on this subject based on the ideXlab platform.

  • sudden and gradual alteration of amplitude during the computation for flow around a cylinder oscillating in transverse or in line direction
    ASME 2009 Pressure Vessels and Piping Conference, 2009
    Co-Authors: Laszlo Baranyi
    Abstract:

    This study investigates the effect of altering oscillation amplitude on time-Mean and root-Mean-Square Values of force coefficients when plotted against amplitude of oscillation. The cylinder is placed in a uniform flow and is oscillated mechanically in transverse or in-line direction. The two-dimensional numerical computations are carried out at Re = 140 and 160, at 90% of the natural vortex shedding frequency. For in-line oscillation, jumps were found in the time-Mean Values of lift and torque. Both abrupt and gradual alteration of amplitude in the course of a computation had the effect of keeping the solution in one state curve, i.e., of conserving state, or inhibiting changes in vortex structure. Transverse oscillation displayed no jumps, and alteration of amplitude had no effect on the solution.Copyright © 2009 by ASME

  • numerical simulation of flow around an orbiting cylinder at different ellipticity Values
    Journal of Fluids and Structures, 2008
    Co-Authors: Laszlo Baranyi
    Abstract:

    This paper deals with the numerical simulation of low Reynolds number flow (Re=120–180) past a circular cylinder in orbital motion. The Navier–Stokes equations, pressure Poisson equations and continuity are written in primitive variables in a noninertial system fixed to the orbiting cylinder and solved by the finite difference method. Ellipticity Values between 0 and 1.2 (from pure in-line oscillation through a full circle and beyond) were investigated. Sudden changes in state (jumps) are found when time-Mean or root-Mean-Square Values of force coefficients or energy transfer are plotted against ellipticity. Pre- and post-jump analysis was carried out by investigating limit cycles, time-histories, phase angles and flow patterns. These investigations revealed that ellipticity can have a large effect on the energy transfer between the incompressible fluid and a circular cylinder forced to follow an orbital path, and that small changes in the amplitude of transverse motion can have a dramatic effect. The phase angle was altered by about 180° at the jumps. Also investigated were the direction of orbit, which affects the state curves belonging to the time-Mean Values of lift only, and the effect of initial conditions, which alters the location of jumps without changing the state curves.

  • abrupt changes in the root Mean Square Values of force coefficients for an orbiting cylinder in uniform stream
    2005
    Co-Authors: Laszlo Baranyi
    Abstract:

    A finite difference solution is presented for 2D laminar unsteady flow around a circular cylinder in orbital motion placed in a uniform stream at Re=120-180. Abrupt switches were found in the time-Mean and rootMean-Square Values of lift, drag and base pressure coefficients under lock-in conditions. The phenomenon was investigated by computations at different Values of Reynolds number, amplitude of in-line oscillation and ellipticity. Plotting against ellipticity suggests two states of vortex shedding exist.

Adrian Diaconu - One of the best experts on this subject based on the ideXlab platform.

  • Mean Square Values of hecke l series formed with r th order characters
    Inventiones Mathematicae, 2004
    Co-Authors: Adrian Diaconu
    Abstract:

    Let L be a number field containing the r–th roots of unity. Starting with the Rankin-Selberg convolution of a metaplectic Eisenstein series on the r–fold cover of GL(2) with itself, we construct a Dirichlet series defined over L whose coefficients involve the r–th order twists of a fixed Hecke L–function. We then observe that a group of functional equations can be naturally associated with this construction. Combining this with the convexity theorem for holomorphic functions of several complex variables, we show that this object, as a function of two complex variables, admits meromorphic continuation to ℂ2. As an application, we obtain asymptotic formulae for Mean Square Values of the r–th order twists of an arbitrary Hecke L–function defined over L.