Insight into Resonant Activation in Discrete Systems

The resonant activation phenomenon (RAP) in a discrete system is studied using the master equation formalism. We show that the RAP corresponds to a non-monotonic behavior of the frequency dependent first passage time probability density function (pdf). An analytical expression for the resonant frequency is introduced, which, together with numerical results, helps understand the RAP behavior in the space spanned by the transition rates for the case of reflecting and absorbing boundary conditions. The limited range of system parameters for which the RAP occurs is discussed. We show that a minimum and a maximum in the mean first passage time (MFPT) can be obtained when both boundaries are absorbing. Relationships to some biological systems are suggested.Comment: 5 pages, 5 figures, Phys. Rev. E., in pres

The synthesis of 15 mu infrared horizon radiance profiles from meteorological data inputs

Computational computer program for modeling infrared horizon radiance profile using pressure and temperature profile input

COMPARISON OF RIGHT VS. LEFT LEG GRF LANDING SYMMETRY FOR HEALTHY AND OVERUSE INJURY-PRONE RECREATIONAL ATHLETES

PURPOSE AND METHODS The purpose of the study was to compare right versus left leg symmetry during landing for healthy (n = 10) and overuse injury-prone (n = 10) recreational athletes. Landing symmetry was evaluated by examining vertical ground reaction force (GRF; 1000 Hz) magnitude and temporal variables for each leg and subject group while landing from three different heights (50, 100, and 200% of maximum vertical jump, MVJ). Magnitudes of the first (Fl) and second (F2) maximum force values were identified along with the temporal occurrences of these events (T1 and T2, respectively). Vertical GRF pattern consistency varied among subjects and across heights, therefore, when Fl and F2 could not be individually identified the maximum force magnitude and temporal values for the landing phase were assigned to the F2 and T2 variables, respectively. The F2 and T2 values were utilized to evaluate differences between legs (one-way Analysis of Variance, ANOVA; = 0.05) for each group and landing height. Additionally, GRF pattern consistency between right and left legs (for both subject groups) was monitored by a tally which tracked the number of unimodal (single peak) curves for each landing height. RESULTS Results of the ANOVA procedures indicated no significant differences (p > 0.05) between the right and left side GRF magnitude or temporal variables for the healthy subject group. The injury prone group exhibited significant right-left side differences for the 50% MVJ height (p < 0.01; right greater than left) and for the 100% MVJ height condition (p < 0.05; right greater than left). No right-left temporal differences were observed for the injury prone group. Results of the descriptive GRF tally for the occurrence of unimodal landing curve patterns suggest that the injury prone group might have been more consistent between legs in producing traditional bimodal GRF-time histories. A unimodal curve was defined as a GRF-time history that did not follow the typical bimodal (Fl-toe, F2-heel) landing pattern. The 50% MVJ height elicited a right-left unimodal curve count of 21 and 30, respectively, for the healthy group and 19 and 19, respectively, for the injury prone subjects. For the 100% MVJ height condition the healthy group exhibited a total (sum of all subjects) of two right side and three left side unimodal curves, while the injury prone group exhibited no unimodal curves from either leg. No unimodal curves were detected for either subject group while landing from the 200% MVJ height. CONCLUSIONS The functional significance of these results is not clear. However, one might speculate that the asymmetrical GRF magnitude values observed for the injury prone group are related to their injury history, although the causeeffect relationship cannot be determined from these data. The number of differences between right and left leg unimodal curves might be related to the amount of movement variability exhibited by each subject group. The fewer total number of unimodal curves and the fewer number of right-left differences suggest less performance variability for theinjury prone group

Multi-objective evolutionary–fuzzy augmented flight control for an F16 aircraft

In this article, the multi-objective design of a fuzzy logic augmented flight controller for a high performance fighter jet (the Lockheed-Martin F16) is described. A fuzzy logic controller is designed and its membership functions tuned by genetic algorithms in order to design a roll, pitch, and yaw flight controller with enhanced manoeuverability which still retains safety critical operation when combined with a standard inner-loop stabilizing controller. The controller is assessed in terms of pilot effort and thus reduction of pilot fatigue. The controller is incorporated into a six degree of freedom motion base real-time flight simulator, and flight tested by a qualified pilot instructor

Finite to infinite steady state solutions, bifurcations of an integro-differential equation

We consider a bistable integral equation which governs the stationary solutions of a convolution model of solid--solid phase transitions on a circle. We study the bifurcations of the set of the stationary solutions as the diffusion coefficient is varied to examine the transition from an infinite number of steady states to three for the continuum limit of the semi--discretised system. We show how the symmetry of the problem is responsible for the generation and stabilisation of equilibria and comment on the puzzling connection between continuity and stability that exists in this problem

A Special Homotopy Continuation Method For A Class of Polynomial Systems

A special homotopy continuation method, as a combination of the polyhedral homotopy and the linear product homotopy, is proposed for computing all the isolated solutions to a special class of polynomial systems. The root number bound of this method is between the total degree bound and the mixed volume bound and can be easily computed. The new algorithm has been implemented as a program called LPH using C++. Our experiments show its efficiency compared to the polyhedral or other homotopies on such systems. As an application, the algorithm can be used to find witness points on each connected component of a real variety