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The presented list of electrical engineering drawings ranges from the high frequency logistic acquisition counter and binary register to the target tracker power supply system.
The most ancient and fundamental concern of astronomy is the orientation and motion of a terrestrial observer relative to the stars. Its geophysical aspects date from the time of Newton and Halley, and its mathematical foundations were laid by Euler 200 years ago. Despite this honorable antiquity, the subject is far from moribund and today presents a rich and fascinating array of challenges to observation, experiment, data analysis, and theory. The many‐faceted problems of the three‐dimensional rotation of the earth about its center of mass now attract astronomers and paleontologists, solid earth geophysicists and electrical engineers, general relativists and oceanographers, and applied mathematicians and scholars of classical texts.
The Electrical Engineering Department of North Carolina Agricultural and Technical State University has developed a microelectronics laboratory as a result of research involving microelectronics and metallic-oxide studies over the past five years. Work on characterization and applications of metallic-oxide devices is currently being conducted. This paper reports on the fabrication of eight oscillator devices on a 1-in. square alumina substrate using metallic-oxide materials developed as a result of the research program. Significant technological capabilities of the laboratory relative to the microelectronics industry in the area of microelectronic-component evaluation are also discussed.
Materials illustrating a presentation on electric propulsion systems are presented. The electric engine and engine/generator configurations are described and NASA's role outlined.
The primary objective of this study is to evaluate the relationships between soil moisture and reflectivity of a bare soil, using microwave techniques. A drainage experiment was conducted on a Captina silt loam in cooperation with personnel in the Electrical Engineering Department. Measurements included soil moisture pressures at various depths, neutron probe measurements, gravimetric moisture samples, and reflectivity of the soil surface at selected frequencies including 1.5 and 6.0 GHz and at the incident angle of 45 deg. All measurements were made in conjuction with that of reflectivity data.
Many recent theories and methods proposed for visual preprocessing and shape representation are summarized. The survey brings together research from the fields of biology, psychology, computer science, electrical engineering, and most recently, neural networks. It was motivated by the need to preprocess images for a sparse distributed memory (SDM), but the techniques presented may also prove useful for applying other associative memories to visual pattern recognition. The material of this survey is divided into three sections: an overview of biological visual processing; methods of preprocessing (extracting parts of shape, texture, motion, and depth); and shape representation and recognition (form invariance, primitives and structural descriptions, and theories of attention).
Satellite Sound Broadcasting is an attractive satellite application. Before regulatory decisions can be made in 1992, the propagation effects encountered have to be characterized. The Electrical Engineering Research Laboratory has nearly completed a system which will allow amplitude measurements to be made over 10 MHz bandwidths in the 800 to 1800 MHz frequency range. The system uses transmission from a transportable tower, and reception inside buildings or in the shadow of trees or utility poles. The goal is to derive propagation models for use by systems engineers who are about to design satellite broadcast systems. The advance of fiber-optics technology has helped to focus future development of satellite services into areas where satellites are uniquely competitive. One of these preferred satellite applications is the broadcasting of high-quality sound for stationary or mobile reception by listeners using low-cost, consumer-grade receivers. Before such services can be provided, however, the political hurdles of spectrum allocation have to be surmounted and the technical questions of standardization for world-wide compatibility have to be resolved. In order to arrive at an optimal system design, efficient in the use of our scarce spectral resources, affordable both to the broadcaster and the listener, and providing predictable performance, the propagation effects to which the service is subjected have to be characterized. Consequently, the objective of the research project is to make basic propagation measurements for direct Satellite Sound Broadcasting Service (SSBS). The data obtained should allow the development of propagation models to be used by communications engineers designing the operational systems. Such models shall describe the effects of shadowing and multipath propagation on SSBS receivers operating in a specified environment, such as inside commercial or residential buildings of various construction and also in the shadow of trees or utility poles as might be encountered by transporting or mobile listeners.
During the period 1983 to 1988 a series of experiments were undertaken by the Electrical Engineering Research Laboratory of the University of Texas and the Applied Physics Laboratory of the Johns Hopkins University in which propagation impairment effects were investigated for the Land Mobile Satellite Service (LMSS). The results of these efforts have appeared in a number of publications, technical reports, and conference proceedings. The rationale for the development of a 'handbook' was to locate the salient and useful results in one single document for use by communications engineers, designers of planned LMSS communications systems, and modelers of propagation effects. Where applicable, the authors have also drawn from the results of other related investigations. A description of sample results contained in this handbook which should be available in the latter part of 1990 is given.
The Valkyrie flying wing concept is a remotely piloted technology demonstrator designed to serve as a high volume commuter transport in Aeroworld. The 5.02 lb Valkyrie has a planform area of 1440 sq in and a wingspan of 84 in, which results in an aspect ratio of 4.9. The Valkyrie uses the NACA 2R(2)12 airfoil section. A leading edge wing sweep of 13.2 deg and a 2 deg dihedral were incorporated to provide lateral stability. The Valkyrie is semi-monocoque structure manufactured from spruce and balsa wood covered in plastic Mylar skin. The AstroFlight Cobolt 25 electric engine will power the Valkyrie with a Tornado 10-6 propeller. The Valkyrie is designed to take off in less than 20 ft. To eliminate the difficulties associated with rotating the aircraft at takeoff, the wing is mounted on its landing gear at the take off angle of attack of 8 deg. The Valkyrie provides a greater payload to weight ratio than a conventionally configured aircraft of comparable weight. Considering the requirements, the Valkyrie is the most efficient design for the specified mission.
In this summary, we present the main conclusions and results of a design study conducted by a group of 25 students at the University of Maryland. The students, all participants in the spring 1988 courses ENEE488Q and ENEE418 in the Electrical Engineering Department, considered the problem of designing a free-flying space robot for applications in satellite servicing. In addition to the paper study, a subgroup of eight students undertook the ambitious task of designing and building a laboratory testbed for the concept of a free flyer. This subgroup has already completed the main fabrication of the mechanical hardware and most of the onboard electronics. When completed by the end of the summer, the testbed will consist of a seven-degree-of-freedom dual-armed planar robot that will float on an air table and carry out various commanded tasks. All the fabrication and testing is being conducted in the Intelligent Servosystems Laboratory at the University of Maryland. The project team split up into subgroups as follows: (1) articulation concepts 1 and 2, to study competing ideas for the overall systems architecture and manipulator design; (2) real time control systems group; (3) a computer graphics group to provide animations of a planar design; (4) a mechanical hardware design group for the laboratory testbed; and (5) a control systems hardware design group for the same.
This summary presents the main conclusions and results of the design studies conducted by a group of 13 students at the University of Maryland. The students, all participants in the spring 1989 course ENEE418 in the Electrical Engineering Department, met weekly in a two-hour class to discuss and evaluate design alternatives. The main problem considered was the design and control of a planar testbed simulating a free-flying space robot for applications in satellite servicing. This project grew out of the 1988 class where a dual-armed free flyer (DAFF) was designed and partially built. This year, a group of six students continued the development of the DAFF, achieving computer-controlled motion of the DAFF's arms. All fabrication and testing of the DAFF is being conducted in the Intelligent Servosystems Laboratory at the University of Maryland. While the work related to the design and development of the DAFF is the main subject of the report, it should be noted that other students in the ENEE418 class have investigated additional issues related to manipulation in space. For example, one group studied a new parallel linkage based manipulator for fine motion applications such as in assembly operations in space. They investigated the mechanism's kinematics, its reachable workspace, and precision of applying forces and torques. In yet another project, a student set out to measure and map the friction characteristics of the actuators used in the Modular Dextrous Hand, which has been recently developed in the Intelligent Servosystems Laboratory. The results are expected to help compensate for this friction, which is a highly nonlinear disturbance and presents significant problems in high-precision, low-speed operations. This summary continues with the discussion of the results obtained by the group of students who have been working on developing the DAFF testbed.
This video includes STS 3 & 4, Challenger completed, unmanned launches, the Hubble Space Telescope, Pioneers 8 & 9 encounter, Mars Pictures, Landsat 4, wind energy, ion-electric engines, solar powered medical system, medical image analysis, rotor systems research aircraft, XV-15, propfan research, aircraft icing studies, and Oshkosh Sirshow.
A program is underway to develop a YAG laser based materials processing workstation to fly in the cargo bay of the Space Shuttle. This workstation, called Space Applications Industrial Laser System (SAILS), will be capable of cutting and welding steel, aluminum, and Inconel alloys of the type planned for use in constructing the Space Station Freedom. As well as demonstrating the ability of a YAG laser to perform remote (fiber-optic delivered) repair and fabrication operations in space, fundamental data will be collected on these interactions for comparison with terrestrial data and models. The flight system, scheduled to fly in 1996, will be constructed as three modules using standard Get-Away-Special (GAS) canisters. The first module holds the laser head and cooling system, while the second contains a high peak power electrical supply. The third module houses the materials processing workstation and the command and data acquisition subsystems. The laser head and workstation cansisters are linked by a fiber-optic cable to transmit the laser light. The team assembled to carry out this project includes Lumonics Industrial Products (laser), Tennessee Technological University (structural analysis and fabrication), Auburn University Center for Space Power (electrical engineering), University of Waterloo (low-g laser process consulting), and CSTAR/UTSI (data acquisition, control, software, integration, experiment design). This report describes the SAILS program and highlights recent activities undertaken at CSTAR.
An overview of two planned propagation campaigns employing land-mobile scenarios with ACTS is presented. The campaigns will be undertaken through a joint effort involving the Johns Hopkins University, Applied Physics Laboratory (APL), The University of Texas at Austin, Electrical Engineering Research Laboratory (EERL), and the NASA Lewis Research Center (NASA LeRC). Propagation campaigns are planned in Central Maryland in November 1993 (elevation angle approx. equals 40 deg.) and in Fairbanks, Alaska in June 1994 (elevation angle approx. equals 8 deg.) employing a computer controlled antenna tracking system located atop a van containing a receiver/data acquisition system. The antenna will track (in azimuth) downlink transmissions at 19.914 GHz from ACTS during the mobile propagation measurements. The major objectives of the campaigns are to measure the fade and multipath effects of trees and terrain at 20 GHz for rural and suburban scenarios and to extend existing models which were previously validated at UHF to S-Band.
In this hardware project the students designed the prototype of a novel mini-rover for the exploration of a planetary surface. In an actual application, a large number of such miniature roving devices would be released from a landing craft. Each rover would be equipped with a Cd 109 radio-isotope source (a gamma ray emitter) irradiating the planetary surface below the rover, and an x-ray fluorescence detector for a quantitative assay of high atomic weight elements in the planet's surface. (Similar, miniaturized, hand-held devices have recently been developed for use in gold mines). The device developed by the students was limited to demonstrating the mechanical and electrical drive. The geometric external shape is a sphere; hence there is no danger of the rover being turned on its back and stopped. Propulsion is by means of an interior mass, eccentric to the sphere and driven by an electric motor. In an inter-disciplinary effort in mechanical and electrical engineering, the students designed the mechanical parts, built the transistorized circuit board, and tested the device.
STEP (STandard for the Exchange of Product Model Data) is an innovative software tool that allows the exchange of data between different programming systems to occur and helps speed up the designing in various process industries. This exchange occurs easily between those companies that have STEP, and many industries and government agencies are requiring that their vendors utilize STEP in their computer aided design projects, such as in the areas of mechanical, aeronautical, and electrical engineering. STEP allows the process of concurrent engineering to occur and increases the quality of the design product. One example of the STEP program is the Boeing 777, the first paperless airplane.
A research program, involving 3 British universities, directed at quantifying the controllability of High Temperature Superconducting (HTS) magnets for use in attraction levitation transport systems will be described. The work includes measurement of loss mechanisms for iron cored HTS magnets which need to produce a flux density of approx. 1 tesla in the airgap between the magnet poles and a ferromagnetic rail. This flux density needs to be maintained and this is done by introducing small variations of the magnet current using a feedback loop, at frequencies up to 10 Hz to compensate for load changes, track variation etc. The test magnet assemblies constructed so far will be described and the studies and modelling of designs for a practical levitation demonstrator (using commercially obtained HTS tape) will be discussed with particular emphasis on how the field distribution and its components, e.g., the component vector normal to the broad face of the tape, can radically affect design philosophy compared to the classical electrical engineering approach. Although specifically aimed at levitation transport the controllability data obtained have implications for a much wider range of applications.
The project Fine Collimator Grids Using Silicon Metering Structure was managed by Dr. Carol Eberhard of the Electromagnetic Systems & Technology Department (Space & Technology Division) of TRW who also wrote this final report. The KOH chemical etching of the silicon wafers was primarily done by Dr. Simon Prussin of the Electrical Engineering Department of UCLA at the laboratory on campus. Moshe Sergant of the Superconductor Electronics Technology Department (Electronics Systems & Technology Division) of TRW and Dr. Prussin were instrumental in developing the low temperature silicon etching processes. Moshe Sergant and George G. Pinneo of the Microelectronics Production Department (Electronics Systems & Technology Division) of TRW were instrumental in developing the processes for filling the slots etched in the silicon wafers with metal-filled materials. Their work was carried out in the laboratories at the Space Park facility. Moshe Sergant is also responsible for the impressive array of Scanning Electron Microscope images with which the various processes were monitored. Many others also contributed their time and expertise to the project. I wish to thank them all.