Wake and diffusion structure behind a model industrial complex, The

CER81-82KMK-JAP-RNM19.November 1981.NRC FIN B5829.NUREG/CR-1473.Bibliography: pages 29-31.Prepared for Division of Health, Siting, and Waste Management, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission under contract no. NRC 04-76-236

Wind-tunnel measurements of dispersion and turbulence in the wakes of nuclear reactor plants: final report, January 1975-December 1979

September 1980.NRC FIN no. B5829.NUREG/CR-1475, RB, R6.CER79-80RNM-JAP-KMK32.Includes bibliographical references (pages 41-45).Prepared for Division of Reactor Safety Research, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission under contract no. NRC-04-76-236

Asymmetry measures for quantification of mechanisms contributing to dynamic stability during stepping-in-place gait

The goal of this study is to introduce and to motivate the use of new quantitative methods to improve our understanding of mechanisms that contribute to the control of dynamic balance during gait. Dynamic balance refers to the ability to maintain a continuous, oscillating center-of-mass (CoM) motion of the body during gait even though the CoM frequently moves outside of the base of support. We focus on dynamic balance control in the frontal plane or medial–lateral (ML) direction because it is known that active, neurally-mediated control mechanisms are necessary to maintain ML stability. Mechanisms that regulate foot placement on each step and that generate corrective ankle torque during the stance phase of gait are both known to contribute to the generation of corrective actions that contribute to ML stability. Less appreciated is the potential role played by adjustments in step timing when the duration of the stance and/or swing phases of gait can be shortened or lengthened to allow torque due to gravity to act on the body CoM over a shorter or longer time to generate corrective actions. We introduce and define four asymmetry measures that provide normalized indications of the contribution of these different mechanisms to gait stability. These measures are ‘step width asymmetry’, ‘ankle torque asymmetry’, ‘stance duration asymmetry’, and ‘swing duration asymmetry’. Asymmetry values are calculated by comparing corresponding biomechanical or temporal gait parameters from adjacent steps. A time of occurrence is assigned to each asymmetry value. An indication that a mechanism is contributing to ML control is obtained by comparing asymmetry values to the ML body motion (CoM angular position and velocity) at the time points associated with the asymmetry measures. Example results are demonstrated with measures obtained during a stepping-in-place (SiP) gait performed on a stance surface that either remained fixed and level or was pseudorandomly tilted to disturb balance in the ML direction. We also demonstrate that the variability of asymmetry measures obtained from 40 individuals during unperturbed, self-paced SiP were highly correlated with corresponding coefficient of variation measures that have previously been shown to be associated with poor balance and fall risk

Wind engineering study of the Interama Tower of the Sun

CER74-75JAP-JEC23.Includes bibliographical references (pages 34-35).January 1975.For Ferendino-Grafton-Spillis-Candela.Support for this investigation was provided by Ferendino-Grafton-Spillis-Candela Architects and the Interama Authority of Miami

Finitely-Generated Projective Modules over the Theta-deformed 4-sphere

We investigate the "theta-deformed spheres" C(S^{3}_{theta}) and C(S^{4}_{theta}), where theta is any real number. We show that all finitely-generated projective modules over C(S^{3}_{theta}) are free, and that C(S^{4}_{theta}) has the cancellation property. We classify and construct all finitely-generated projective modules over C(S^{4}_{\theta}) up to isomorphism. An interesting feature is that if theta is irrational then there are nontrivial "rank-1" modules over C(S^{4}_{\theta}). In that case, every finitely-generated projective module over C(S^{4}_{\theta}) is a sum of a rank-1 module and a free module. If theta is rational, the situation mirrors that for the commutative case theta=0.Comment: 34 page

Evolution of central pattern generators for the control of a five-link bipedal walking mechanism

Central pattern generators (CPGs), with a basis is neurophysiological studies, are a type of neural network for the generation of rhythmic motion. While CPGs are being increasingly used in robot control, most applications are hand-tuned for a specific task and it is acknowledged in the field that generic methods and design principles for creating individual networks for a given task are lacking. This study presents an approach where the connectivity and oscillatory parameters of a CPG network are determined by an evolutionary algorithm with fitness evaluations in a realistic simulation with accurate physics. We apply this technique to a five-link planar walking mechanism to demonstrate its feasibility and performance. In addition, to see whether results from simulation can be acceptably transferred to real robot hardware, the best evolved CPG network is also tested on a real mechanism. Our results also confirm that the biologically inspired CPG model is well suited for legged locomotion, since a diverse manifestation of networks have been observed to succeed in fitness simulations during evolution.Comment: 11 pages, 9 figures; substantial revision of content, organization, and quantitative result

Emission decay and energy transfer in Yb/Tm Y-codoped fibers based on nano-modified glass

We report the results of an experimental investigation and theoretical analysis of luminescence decay in Yb/Tm Y-codoped fibers based on nano-modified glass. Based on the experimental results, numerical simulations allowed us to estimate the energy transfer efficiency between Yb3+ and Tm3+ ions. It was shown that yttria enhances the Yb/Tm energy transfer making fibers with Y-codoping a promising candidate for the development of light sources for laser applications and up-conversion emitters for visualization applications. These fibers demonstrate energy transfer efficiency of ∼50%, which makes them attractive for diode-pumping of Yb-ions at a wavelength of 975 nm

Self versus Environment Motion in Postural Control

To stabilize our position in space we use visual information as well as non-visual physical motion cues. However, visual cues can be ambiguous: visually perceived motion may be caused by self-movement, movement of the environment, or both. The nervous system must combine the ambiguous visual cues with noisy physical motion cues to resolve this ambiguity and control our body posture. Here we have developed a Bayesian model that formalizes how the nervous system could solve this problem. In this model, the nervous system combines the sensory cues to estimate the movement of the body. We analytically demonstrate that, as long as visual stimulation is fast in comparison to the uncertainty in our perception of body movement, the optimal strategy is to weight visually perceived movement velocities proportional to a power law. We find that this model accounts for the nonlinear influence of experimentally induced visual motion on human postural behavior both in our data and in previously published results