Manual Tracking Flight Control with Amplitude and Rate Constrained Dynamic Actuators

A new control methodology for manual flight control, viz., real-time tracking control, is developed. Amplitude and rate constrained dynamic actuators are considered. Optimal tracking control is made possible by the use of unique reference signal prediction strategies which extrapolate the reference signal over the optimization horizon. A receding horizon, linear-quadratic inner-loop controller is employed in conjunction with an outer-loop nonlinear element. The constraint effects mitigation strategy is to optimally track a modified reference signal which yields feasible actuator commands over the optimization horizon when the pilot demanded reference is too aggressive to be tracked by the inner-loop optimal control law. A discrete-time implementation yields computationally inexpensive, closed-form solutions which are implementable in real-time and which afford the optimal tracking of an exogenous, unknown a priori reference signal. The developed control algorithm is applied to an open-loop unstable aircraft model, with attention being given to the trade-offs associated with the conflicting objectives of aggressive tracking and saturation avoidance. One-step ahead constraint mitigation is shown to provide substantial improvement in the constrained system response, while slightly more complicated constraint mitigation strategies yield stronger stability properties

Plan for Reorganization of Secondary School Physics Material

There is a growing demand for a revision of secondary school curricula made on the basis of present day aims of education. The objectives that are almost universally accepted and upon which this revision should be based are as follows: to assist in the production and maintenance of health; to develop and maintain a high standard of social and civic relationships; to make one\u27s chosen vocation more enjoyable and successful; to assist in the proper use of leisure time. In the reorganization, outlined in this paper, an attempt is being made to select the material which will contribute, directly or indirectly, to at least one of the above major objectives, and to exclude any and all material that cannot be justified on this basis

Variation of Intensities of the Visible and of the Ultra Violet in Sunlight and in Skylight

The amounts of radiations received from the sun at 42° N. latitude at various hours of the day throughout the year, both in the visible spectrum and in the ultra violet, were determined experimentally. Curves are plotted and tables are given to show what percent of the total comes from the sky alone in each of these regions of the spectrum. From these data, one may determine the relative amounts of ultra violet or visible radiations received at any two periods of the day or year either from sun and sky combined or from one of these alone

Skyshine and Sunshine at Ames

As an initial step toward determining the amount of ultra violet light in skyshine and in sunshine it was deemed desirable to determine the ratio of skyshine to sunshine in the visible spectrum. Accordingly readings were taken on a horizontal plane on top of a tall building, once with the test plate of a Macbeth illuminometer exposed to the entire dome of the heavens including the sun and again when the sun was blocked out by an opaque disk. Observations were made every hour on perfectly clear days only

Nonlinearities and Effects of Transverse Beam Size in Beam Position Monitors (revised)

The fields produced by a long beam with a given transverse charge distribution in a homogeneous vacuum chamber are studied. Signals induced by a displaced finite-size beam on electrodes of a beam position monitor (BPM) are calculated and compared to those produced by a pencil beam. The non-linearities and corrections to BPM signals due to a finite transverse beam size are calculated for an arbitrary chamber cross section. Simple analytical expressions are given for a few particular transverse distributions of the beam current in a circular or rectangular chamber. Of particular interest is a general proof that in an arbitrary homogeneous chamber the beam-size corrections vanish for any axisymmetric beam current distribution.Comment: REVTeX, 8 pages, 9 figures. Corrected Eqs. (7),(22),(25) and Figs. 2-9. Expande

Immigrants in the Ozarks: A Study in Ethnic Geography

International audienc

Progress in cavity QED with single trapped atoms

We report on recent progress in our lab involving cavity quantum electrodynamics with optically trapped atoms. In particular, we will focus on a recent measurement of the Vacuum-Rabi splitting for one atom strongly coupled to the field of a high finesse optical resonator. This splitting is characteristic of the normal modes in the eigenvalue spectrum of the atom-cavity system. A new Raman scheme for cooling atomic motion along the cavity axis enables a complete spectrum to be recorded for an individual atom trapped within the cavity mode, in contrast to all previous measurements in cavity QED that have required averaging over many atoms

Age and growth, reproduction and diet of a sublittoral population of the rock goby Gobius paganellus (Teleostei, Gobiidae)

Copyright © 2000 Kluwer Academic Publishers. Printed in the Netherlands.Basic biological information for a sublittoral population of the rock goby Gobius paganellus Linnaeus, 1758 is presented based on a 2-year study involving 1680 specimens. The length-weight relationship was given by TW = 0.0089 * TL^3,163 (where TW= total weight in g; TL= total length in mm). Age at length data were inferred by modal analysis of the monthly length-frequency distributions. The parameters of the fitted Von Bertalanffy growth equation (with seasonal component, birth date on the 1st of January) were L1 = 13.8 cm; K = 0.73 yr^-1; to = -0.22 yr; C = 0.95; W = 0.07. This growth rate is much higher than that described for northern Europe populations (where K is about 0.3 yr^-1) and is probably associated with a shorter life span. Macroscopic examination of the gonads, and analysis of the monthly values of the gonadosomatic index, indicated that reproduction occurs in winter and early spring, with a maximum in February and March, when water temperatures are lowest. Individuals become sexually mature around 6-7 cm TL, a size that can be reached in less than 1 year. By contrast, individuals of this goby in the British Isles mature in their second or third year. Stomach contents were mainly small benthic invertebrates, predominantly crustaceans

Shear band dynamics from a mesoscopic modeling of plasticity

The ubiquitous appearance of regions of localized deformation (shear bands) in different kinds of disordered materials under shear is studied in the context of a mesoscopic model of plasticity. The model may or may not include relaxational (aging) effects. In the absence of relaxational effects the model displays a monotonously increasing dependence of stress on strain-rate, and stationary shear bands do not occur. However, in start up experiments transient (although long lived) shear bands occur, that widen without bound in time. I investigate this transient effect in detail, reproducing and explaining a t^1/2 law for the thickness increase of the shear band that has been obtained in atomistic numerical simulations. Relaxation produces a negative sloped region in the stress vs. strain-rate curve that stabilizes the formation of shear bands of a well defined width, which is a function of strain-rate. Simulations at very low strain-rates reveal a non-trivial stick-slip dynamics of very thin shear bands that has relevance in the study of seismic phenomena. In addition, other non-stationary processes, such as stop-and-go, or strain-rate inversion situations display a phenomenology that matches very well the results of recent experimental studies.Comment: 10 pages, 10 figure