Efficient sampling of band-limited signals from sine wave crossings

This correspondence presents an efficient method for reconstructing a band-limited signal in the discrete domain from its crossings with a sine wave. The method makes it possible to design A/D converters that only deliver the crossing timings, which are then used to interpolate the input signal at arbitrary instants. Potentially, it may allow for reductions in power consumption and complexity in these converters. The reconstruction in the discrete domain is based on a recently-proposed modification of the Lagrange interpolator, which is readily implementable with linear complexity and efficiently, given that it re-uses known schemes for variable fractional-delay (VFD) filters. As a spin-off, the method allows one to perform spectral analysis from sine wave crossings with the complexity of the FFT. Finally, the results in the correspondence are validated in several numerical examples.

Rail-highway crossing resource allocation model. Final report.

Federal Railway Administration, Office of Safety, Washington, D.C.

Models of pedestrian crossing behavior at signalized intersections.

Texas Department of Transportation, Austin

Railroad grade crossing passive signing study. Final report.

Federal Highway Administration, Office of Research, Washington, D.C.

Models of pedestrian crossing behavior at signalized intersections.

Texas Department of Transportation, Austin

Motorists' requirements for active grade crossing warning devices. Final report.

Federal Highway Administration, Traffic Systems Division, Washington, D.C.

A methodology for determination of grade crossing resource-allocation guidelines. Final report.

Federal Railroad Administration, Office of Research and Development, Washington, D.C.

Railroad grade crossing passive signing study. Interim report.

Federal Highway Administration, Office of Research, Washington, D.C.

Summary of the DOT rail-highway crossing resource allocation procedure - revised. Final report.

Federal Railroad Administration, Office of Safety, Washington, D.C.

Summary statistics of the National Railroad-Highway Crossing Inventory for public at-grade crossings.

Federal Railroad Administration, Office of Policy and Program Development, Washington, D.C.

Rail-highway crossing warning device - life cycle cost analysis. Final report.

Federal Railroad Administration, Office of Safety, Washington, D.C.

Innovative concepts and technology for railroad-highway grade crossing motorist warning systems. Vol. I: overview and concept generation and analysis. Final report.

Transportation Systems Center, Cambridge, Mass.

Innovative concepts and technology for railroad-highway grade crossing motorist warning systems. Vol. II: the generation and analysis of alternative concepts. Final report.

Transportation Systems Center, Cambridge, Mass.

Obstacle Crossing With Dual Tasking Is A Danger For Individuals With Alzheimer's Disease And For Healthy Older People.

The aim of this study was to analyze the effects of dual tasking on obstacle crossing during walking by individuals with Alzheimer's disease (AD) and by healthy older people. Thirty four elderly individuals (16 healthy subjects and 18 individuals with AD) were recruited to participate in this study. Three AD individuals and one control participant were excluded due to exclusion criteria. The participants were instructed to walk barefoot at their own speed along an 8 m long pathway. Each participant performed five trials for each condition (unobstructed walking, unobstructed walking with dual tasking, and obstacle crossing during walking with dual tasking). The trials were completely randomized for each participant. The mid-pathway stride was measured in the unobstructed walking trials and the stride that occurred during the obstacle avoidance was measured in the trials that involved obstacle crossing. The behavior of the healthy elderly subjects and individuals with AD was similar for obstacle crossing during walking with dual tasking. Both groups used the posture first strategy to prioritize stability and showed decreased attention to executive tasking while walking. Additionally, AD had a strong influence on the modifications that are made by the elderly while walking under different walking conditions.

Chaotic Patterns in Aeroelastic Signals

This work presents the analysis of nonlinear aeroelastic time series from wing vibrations due to airflow separation during wind tunnel experiments. Surrogate data method is used to justify the application of nonlinear time series analysis to the aeroelastic system, after rejecting the chance for nonstationarity. The singular value decomposition (SVD) approach is used to reconstruct the state space, reducing noise from the aeroelastic time series. Direct analysis of reconstructed trajectories in the state space and the determination of Poincare sections have been employed to investigate complex dynamics and chaotic patterns. With the reconstructed state spaces, qualitative analyses may be done, and the attractors evolutions with parametric variation are presented. Overall results reveal complex system dynamics associated with highly separated flow effects together with nonlinear coupling between aeroelastic modes. Bifurcations to the nonlinear aeroelastic system are observed for two investigations, that is, considering oscillations-induced aeroelastic evolutions with varying freestream speed, and aeroelastic evolutions at constant freestream speed and varying oscillations. Finally, Lyapunov exponent calculation is proceeded in order to infer on chaotic behavior. Poincare mappings also suggest bifurcations and chaos, reinforced by the attainment of maximum positive Lyapunov exponents. Copyright (C) 2009 F. D. Marques and R. M. G. Vasconcellos.