Nodding feed antenna for communications with satellites in synchronous orbit

The design, fabrication, and performance of a parabolic, ground receiving antenna system with a feed that nods in one axis producing a maximum beam deviation 1.1 deg from boresight is described. The antenna design was: (1)to lower the weight (and the subsequent cost) of the supporting structure and the actuator motors for a tracking antenna by moving just the feed; (2) to use a manual tracking system eliminating the need for expensive electronic controls or computers; (3) to provide for several hours of unattended operation; and (4)to permit operation of the antenna by unskilled personnel. Also described are some physical and orbital phenomenon that effect the operation or design of the antenna. One is the motion of a nearly geostationary satellite due to gravitational forces from the sun, the moon, and other stellar bodies. Others are the rotation of the nodding axis and the feed polarization as a function of the location of the station on the earth. A comparison of per unit cost was made for one unit and a quantity of 100

A design concept for an MMIC microstrip phased array

A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka band advanced satellite communication antenna systems. The proposed design concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required. The proposed design concept takes into consideration the RF characteristics and actual phyical dimensions of the MMIC devices. Also, solutions to spatial constraints and interconnections associated with currently available packaging designs are discussed. Finally, the design of the microstrip radiating elements and their radiation characteristics are examined

A study of optimum cowl shapes and flow port locations for minimum drag with effective engine cooling, volume 2

The listings, user's instructions, sample inputs, and sample outputs of two computer programs which are especially useful in obtaining an approximate solution of the viscous flow over an arbitrary nonlifting three dimensional body are provided. The first program performs a potential flow solution by a well known panel method and readjusts this initial solution to account for the effects of the boundary layer displacement thickness, a nonuniform but unidirectional onset flow field, and the presence of air intakes and exhausts. The second program is effectually a geometry package which allows the user to change or refine the shape of a body to satisfy particular needs without a significant amount of human intervention. An effort to reduce the cruise drag of light aircraft through an analytical study of the contributions to the drag arising from the engine cowl shape and the foward fuselage area and also that resulting from the cooling air mass flowing through intake and exhaust sites on the nacelle is presented. The programs may be effectively used to determine the appropriate body modifications or flow port locations to reduce the cruise drag as well as to provide sufficient air flow for cooling the engine

Characterization of MMIC devices for active array antennas

Certain aspects of monolithic microwave integrated circuit (MMIC) interconnectivity were investigated. Considerations that lead to preserving the inherently reproducible characteristics of the MMIC are proposed. It is shown that at radio frequencies (RF) greater than 20 GHz, the transition from the MMIC device to other transmission media must be an accurate RF match. It is proposed that the RF match is sufficiently critical to include the transition as part of the delivered MMIC package. The model to analyze several transitions is presented. This model consists of a succession of abrupt discontinuities in printed circuit transmission lines. The analysis of these discontinuities is achieved by the Spectral Galerkin technique, to establish the modes and mode matching, to generate the generalized S parameters of the individual discontinuities. Preliminary results achieved with this method are presented. It is concluded that special effects should be coordinated by the active array antenna industry toward standardization of MMIC packaging and characterization

A fast acting electrical servo for the actuation of full span, Fowler-type wing flaps in DLC applications: A detail design study

The philosophy and detail design of an electro-mechanical actuator for Fowler-type wing flaps which have a response time constant of 0.025 seconds are described. A conventional electrical servomotor with a power rating twice the maximum power delivered to the load is employed along with adaptive, gain-scheduled feedback and various logic circuits, including one to remove electrical excitation from the motor during extended periods when no motion of the flap is desired

Automated design of minimum drag light aircraft fuselages and nacelles

The constrained minimization algorithm of Vanderplaats is applied to the problem of designing minimum drag faired bodies such as fuselages and nacelles. Body drag is computed by a variation of the Hess-Smith code. This variation includes a boundary layer computation. The encased payload provides arbitrary geometric constraints, specified a priori by the designer, below which the fairing cannot shrink. The optimization may include engine cooling air flows entering and exhausting through specific port locations on the body

A study of the relative effectiveness and cost of computerized information retrieval in the interactive mode

Results of a number of experiments to illuminate the relative effectiveness and costs of computerized information retrieval in the interactive mode are reported. It was found that for equal time spent in preparing the search strategy, the batch and interactive modes gave approximately equal recall and relevance. The interactive mode however encourages the searcher to devote more time to the task and therefore usually yields improved output. Engineering costs as a result are higher in this mode. Estimates of associated hardware costs also indicate that operation in this mode is more expensive. Skilled RECON users like the rapid feedback and additional features offered by this mode if they are not constrained by considerations of cost

The effect of seaweed meal on yolk colour

Could seaweed, plentiful on local beaches, be used to improve egg yolk colour? This article gives the results of experiments at the Department\u27s Poultry Research Station

School Science Capacity: A Study of Four Urban Catholic Grade Schools

Working from the view of schools as a system, and of school improvement as an ongoing journey (Hallinger & Heck, 2011; Jackson, 2000), this study investigated the perspectives of teacher leaders and principals from four metropolitan Catholic grade schools engaged in efforts to improve their school science programs. Built upon existing conceptualizations of school capacity, a model of school science capacity is presented and used as a framework for the development of four case studies. Findings gleaned from collecting and analyzing reports of teacher leaders’ and principals’ interpretations of their school systems illustrate how elements of the school science capacity framework interacted to support and at times constrain, the schools’ science improvement efforts. Implications for Catholic school educators, administrators, and researchers who seek to make science a priority, and build school science capacity, are discussed. Capacité scientifique à l’école : une étude menée dans quatre écoles primaires catholiques en milieu urbain Partant du concept que les écoles constituent un système et que leur amélioration est une quête perpétuelle (Hallinger & Heck, 2011; Jackson, 2000), cette enquête étudie sur les points de vue des responsables enseignants et chefs d’établissement de quatre écoles secondaires catholiques métropolitaines qui ont entrepris d’améliorer les programmes scientifiques dans leurs écoles. Elle décrit un modèle de capacité scientifique pour l’école, basé sur les conceptualisations existantes sur les capacités des écoles, et l’utilise comme cadre pour la présentation de quatre études de cas. Les constations tirées de l’analyse des rapports établis par les responsables enseignants et chefs d’établissement qui ont interprété leurs systèmes scolaires illustrent de quelle manière des éléments du cadre de la capacité scientifique des écoles interagissent pour soutenir, et parfois restreindre, les actions menées par les écoles pour améliorer l’enseignement des sciences. Cette étude discute des implications pour les établissements d’enseignement, les administrateurs et chercheurs catholiques qui essaient de donner la priorité aux sciences. Capacidad científica de las escuelas: Estudio de cuatros escuelas católicas urbanas Al trabajar desde la perspectiva de las escuelas como sistema y de la mejora escolar como un proyecto en transcurso (Hallinger & Heck, 2011; Jackson, 2000), el presente estudio investiga las perspectivas de docentes líderes y directores de cuatro escuelas católicas metropolitanas involucradas en esfuerzos para mejorar sus programas escolares de ciencias. Este estudio presenta y emplea un modelo de capacidad científica en las escuelas como marco para el desarrollo de cuatro estudios de casos. Los resultados obtenidos de la recopilación y del análisis de las interpretaciones de los informes de docentes líderes y directores de sus sistemas escolares ilustran cómo elementos del marco de capacidad científica de la escuela interactuaban para apoyar y a veces restringir los esfuerzos de mejora científica de las escuelas. Así mismo, el presente trabajo discute implicaciones para la educación en escuelas católicas, personal directivo e investigadores que intentan convertir las ciencias en una prioridad y construir una capacidad científica en las escuelas

Flight test evaluation of predicted light aircraft drag, performance, and stability

A technique was developed which permits simultaneous extraction of complete lift, drag, and thrust power curves from time histories of a single aircraft maneuver such as a pull up (from V max to V stall) and pushover (to V max for level flight). The technique, which is an extension of nonlinear equations of motion of the parameter identification methods of Iliff and Taylor and includes provisions for internal data compatibility improvement as well, was shown to be capable of correcting random errors in the most sensitive data channel and yielding highly accurate results. Flow charts, listings, sample inputs and outputs for the relevant routines are provided as appendices. This technique was applied to flight data taken on the ATLIT aircraft. Lack of adequate knowledge of the correct full throttle thrust horsepower true airspeed variation and considerable internal data inconsistency made it impossible to apply the trajectory matching features of the technique