Introduction to Systems Approach
Main aspects of systems theory are outlined. Emphasis is on the interface of between time and systems - natural or artificial.
Winkler, G. M. R.↗
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Time domain measurement of frequency stability: A tutorial introduction
The theoretical basis behind the definition of frequency stability in the time domain is outlined. Various types of variances were examined. Their differences and interrelation are pointed out. Systems that are generally used in the measurement of these variances are described.
Vanier, J.↗
NASTRAN hydroelastic modal studies. Volume 1: Introduction, theory, and results
The implementation of a general three-dimensional hydroelastic capability in the NASTRAN computer program is described. A method for analyzing the combined mode shapes of arbitrary fluid and structure finite element models was developed. The fluid was modeled with three-dimensional solid elements with options for tetrahedron, wedge, and hexahedron shapes. The elements were then connected to fluid grid points which defined the pressure in the fluid at the specified location. Matrices were formulated to provide efficient solutions for large-order problems. The structure matrices were processed separately and could be reduced using matrix condensation procedures or through a modal formulation using the normal modes of the empty structure as solution coordinates. The fluid/structure interface and the free surface were defined by the user with special NASTRAN boundary elements. A special purpose mesh generator program was provided to generate the actual NASTRAN data cards for the fluid, the structure, and the boundary elements for typical tank-type models.
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Earth Radiation Budget Science, 1978. 1: Introduction
An earth radiation budget satellite system (ERBSS) is planned in order to understand climate on various temporal and spatial scales. The system consists of three satellites and is designed to obtain radiation budget data from the earth's surface. Among the topics discussed are the climate modeling and climate diagnostics, the applications of radiation modeling to ERBSS, and the influence of albedo clouds on radiation budget and atmospheric circulation.
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An introduction to a unified approach to flexible rotor balancing
Two types of technique for flexible-rotor balancing are examined: the influence coefficient method, and the modal balancing method. Briefly, the influence coefficient method seeks those correction masses in a predetermined set of planes which will minimize measured vibration (readings) at a series of sensors and speeds, as predicted by influence coefficients relating vibration readings to mass additions; the influence coefficients are normally determined by a series of trial mass tests. The modal balancing method seeks to balance the rotor, one mode at a time, with a set of masses specifically selected not to disturb previously balanced lower modes, the sensitivity to this combination of masses is determined empirically by a series of trial mass tests. The two approaches are compared in supercritical-shaft balancing tests, and some common features are stressed for ultimate incorporation into a unified approach toward flexible-rotor balancing.
Parkinson, A. G.↗
Considerations associated with the introduction of female crewmembers in spacecraft and space stations
This paper examines considerations of inclusion of female crewmembers in spacecraft and space stations. The anthropometric and physiological differences between males and females as related to spaceflight such as body dimensions, muscle strength characteristics, body posture, reach, and physiological differences are discussed. Crew provisions including inflight garments, hair style, cosmetics, personal hygiene, waste management, and personal privacy are described. Impacts on hardware design and crew performance, examples of effects on Orbiter systems, data on females and their performance under conditions analogous to spaceflight, and earth-based simulation experience are examined. It is concluded that no major problems have been found which would preclude females from space, and in the future the novelty of mixed crews will significantly decrease.
Brown, J. W.↗
An introduction to the BANNING design automation system for shuttle microelectronic hardware development
The BANNING MOS design system is presented. It complements rather than supplant the normal design activities associated with the design and fabrication of low-power digital electronic equipment. BANNING is user-oriented and requires no programming experience to use effectively. It provides the user a simulation capability to aid in his circuit design and it eliminates most of the manual operations involved in the layout and artwork generation of integrated circuits. An example of its operation is given and some additional background reading is provided.
Mcgrady, W. J.↗
Introduction to the Apollo collections: Part 2: Lunar breccias
Basic petrographic, chemical and age data for a representative suite of lunar breccias are presented for students and potential lunar sample investigators. Emphasis is on sample description and data presentation. Samples are listed, together with a classification scheme based on matrix texture and mineralogy and the nature and abundance of glass present both in the matrix and as clasts. A calculus of the classification scheme, describes the characteristic features of each of the breccia groups. The cratering process which describes the sequence of events immediately following an impact event is discussed, especially the thermal and material transport processes affecting the two major components of lunar breccias (clastic debris and fused material).
Mcgee, P. E.↗
Viking Navigation: Introduction
The design, control, and reconstruction of the flight paths of all four Viking vehicles is presented. The specification of requirements on the flight hardware is described along with the navigation strategies, procedures, operational software, and the inflight navigation. Features of the Viking navigation discussed include the precise determination of the spacecraft trajectories, prediction of the trajectories, design of the propulsive maneuvers required to effect the necessary trajectory changes, and calculation of the Lander descent guidance parameters.
Oneil, W. J.↗
Introduction: The challenge of optimum integration of propulsion systems and large space structures
A functional matrix of possible propulsion system characteristics for a spacecraft for deployable and assembled spacecraft structures shows that either electric propulsion or low thrust chemical propulsion systems could provide the propulsion required. The trade-off considerations of a single propulsion engine or multiengines are outlined and it is shown that a single point engine is bounded by some upper limit of thrust for assembled spacecraft. The matrix also shows several additional functions that can be provided to the spacecraft if a propulsion system is an integral part of the spacecraft. A review of all of the functions that can be provided for a spacecraft by an integral propulsion system may result in the inclusion of the propulsion for several functions even if no single function were mandatory. Propulsion interface issues for each combination of engines are identified.
Carlisle, R. F.↗
Heat transfer through turbulent boundary layers - The effects of introduction of and recovery from convex curvature
Measurements have been made of the heat transfer through a turbulent boundary layer on a convexly curved isothermal wall and on a flat plate following the curved section. Data were taken for one free-stream velocity and two different ratios of boundary layer thickness to radius of curvature delta/R = 0.051 and delta/R = 0.077. Only small differences were observed in the distribution of heat transfer rates for the two boundary layer thicknesses tested, although differences were noted in the temperature distributions within the boundary layer
Simon, T. W.↗
Inertial balancing of the Galileo spacecraft - An introduction
Various aspects of the Galileo spacecraft inertial balance are described. Attention is given to the Galileo spacecraft and mission description, the attitude and articulation control and figure of merit requirements, the inertial balance test and verification plan, and the error analysis. Particular consideration is given to aerodynamic effects and the ballasting technique known as asymmetric tank fill.
Muirhead, B. K.↗
Effect of load introduction on graphite epoxy compression specimens
Compression testing of modern composite materials is affected by the manner in which the compressive load is introduced. Two such effects are investigated: (1) the constrained edge effect which prevents transverse expansion and is common to all compression testing in which the specimen is gripped in the fixture; and (2) nonuniform gripping which induces bending into the specimen. An analytical model capable of quantifying these foregoing effects was developed which is based upon the principle of minimum complementary energy. For pure compression, the stresses are approximated by Fourier series. For pure bending, the stresses are approximated by Legendre polynomials.
Reiss, R.↗
Synthetic aperture radar and digital processing: An introduction
A tutorial on synthetic aperture radar (SAR) is presented with emphasis on digital data collection and processing. Background information on waveform frequency and phase notation, mixing, Q conversion, sampling and cross correlation operations is included for clarity. The fate of a SAR signal from transmission to processed image is traced in detail, using the model of a single bright point target against a dark background. Some of the principal problems connected with SAR processing are also discussed.
Dicenzo, A.↗
Introduction to ball bearings
The purpose of a ball bearing is to provide a relative positioning and rotational freedom while transmitting a load between two structures, usually a shaft and a housing. For high rotational speeds (e.g., in gyroscope ball bearings) the purpose can be expanded to include rotational freedom with practically no wear in the bearing. This condition can be achieved by separating the bearing parts with a coherent film of fluid known as an elastohydrodynamic film. This film can be maintained not only when the bearing carries the load on a shaft, but also when the bearing is preloaded to position the shaft to within micro- or nano-inch accuracy and stability. Background information on ball bearings is provided, different types of ball bearings and their geometry and kinematics are defined, bearing materials, manufacturing processes, and separators are discussed. It is assumed, for the purposes of analysis, that the bearing carries no load.
Hamrock, B. J.↗
Shuttle/payload communications and data systems interface analysis: Introduction
Potential problems associated with interfacing payload elements with orbiter communications and data handling elements are identified. Elements include Ku-band signal processor (KuSP), payload signal processor (PSP), payload interrogator (PI), payload data interleaver (PDI) and payload recorder (PR).
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A theoretical study of microwave beam absorption by a rectenna, introduction
The conditions required for a large rectenna array (i.e., reference design) to absorb nearly 100% of transmitted energy were studied. Design parameters including element spacing, and the manner in which these affect scatter were formulated. Amplitudes and directions of scatter and development of strategies for mitigation were also investigated. The effects on rectenna behavior of external factors such as weather and aircraft overflights were determined.
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Potential effects of the introduction of the discrete address beacon system data link on air/ground information transfer problems
This study of Aviation Safety Reporting System reports suggests that benefits should accure from implementation of discrete address beacon system data link. The phase enhanced terminal information system service is expected to provide better terminal information than present systems by improving currency and accuracy. In the exchange of air traffic control messages, discrete address insures that only the intended recipient receives and acts on a specific message. Visual displays and printer copy of messages should mitigate many of the reported problems associated with voice communications. The problems that remain unaffected include error in addressing the intended recipient and messages whose content is wrong but are otherwise correct as to format and reasonableness.
Grayson, R. L.↗