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At least 721 records · Page 40

Report on the multicolor pyrometry session at the Second NASA Non-Contact Temperature-Measurement Workshop

The session met jointly with the other special sessions. Due to time constraints, the concerns of multicolor pyrometry were not addressed in depth. Multicolor pyrometry attempts to determine an object's temperature and emittance as a function of wavelength from simultaneous measurement of the spectral radiance of the object at multiple wavelengths. The main issues are those of the most appropriate model for the wavelength dependence of the emittance, the number of undetermined parameters, and the error in the measured temperature. It has long been known that it is inappropriate to attempt to model the emittance with a functional form that contains as many unknowns as wavelengths. Such attempts will lead to gross errors in the measured temperature. However, more recent work by Hunter and Khan has indicated that emittance can be modeled by a function with many fewer degrees of freedom than sampled wavelengths (e.g., it may be appropriate to use a second order polynomial to fit data from a forty-color pyrometer). In a platform lecture, Khan described algorithms for determination of the parameters by minimization of the errors between the model and the data in a least-squares sense. The first was a linear method and the second was a non-linear method where the emittance could assume any functional form. Both methods were shown to be very sensitive to random noise and non-linearity in the measurement system.

Spjut, R. Erik↗

NASA/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program 1989

Since 1964, NASA has supported a program of summer faculty fellowships for engineering and science educators. The objectives are: to further the professional knowledge of qualified engineering and science faculty; to stimulate and exchange ideas between participants and NASA; to enrich and refresh the research and teachning activities of participants' institutions; and to contribute to the research objectives of the NASA center. College or university faculty members will be appointed as Research Fellows to spend 10 weeks in cooperative research and study at the NASA Langley Research Center. The Fellow will devote approximately 90 percent of the time to a research problem and the remaining time to a study program. The study program will consist of lecture and seminars on topics of interest or that are directly relevant to the Fellows' research topic.

Tiwari, Surendra N.↗

Texstar: The all-Texas educational satellite system

Longhorn Satellite Company (LSC) has designed Texstar, and educational satellite communications system which will be considered as a means of equalizing the distribution of educational resources throughout the state of Texas. Texstar will be capable of broadcasting live lectures and documentaries in addition to transmitting data from a centralized receiving-transmitting station. Included in the design of Texstar is the system and subsystem design for the satellite and the design of the ground stations. The launch vehicle used will be the Texas-built Conestoga 421-48. The Texstar system incorporates three small satellites in slightly inclined geosynchronous orbits. Due to the configuration and spacing of these satellites, the system will be accessed as if it were one large, geostationary satellite. Texstar is shown to be a viable option to the educational crisis in the state of Texas.

Source record↗

NASA/USRA University advanced design program

The participation of the University of Illinois at Urbana-Champaign in the NASA/USRA University Advanced Design Program for the 1988 to 1989 academic year is reviewed. The University's design project was the Logistics Resupply and Emergency Crew Return System for Space Station Freedom. Sixty-one students divided into eight groups, participated in the spring 1989 semester. A presentation prepared by three students and a graduate teaching assistant for the program's summer conference summarized the project results. Teamed with the NASA Marshall Space Flight Center (MSFC), the University received support in the form of remote telecon lectures, reference material, and previously acquired applications software. In addition, a graduate teaching assistant was awarded a summer 1989 internship at MSFC.

Lembeck, Michael F.↗

Technology and the civil future in space; Proceedings of the Twenty-sixth Goddard Memorial Symposium, Greenbelt, MD, Mar. 16-18, 1988

Reviews, reports, lectures, and panel discussions on technological aspects of current and planned NASA space missions are presented. Included are the viewpoints of NASA, the U.S. aerospace industry, potential commercial users of the civil space infrastructure, and university scientists and engineers. Sections are devoted to technology policy and plans, technology needs, technology directions, and the Astronautical Society student program.

Harris, Leonard A.↗

NASA/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program, 1990

Since 1964, NASA has supported a program of summer faculty fellowships for engineering and science educators. The objectives are to further the professional knowledge of qualified engineering and science members; to stimulate and exchange ideas between participants and NASA; to enrich and refresh the research and teaching activities of participants' institutions; and to contribute to the research objectives of the NASA center. The study program consists of lectures and seminars on topics of interest or that are directly relevant to the research topics.

Spencer, John H.↗

Planetary materials and resource utilization: An interdisciplinary engineering design course at Michigan Technological University

A new course was developed and instituted in the spring quarter of 1989 dealing with topics related to space resource utilization and related engineering. The course development required a concerted, coordinated effort, because a similar course which might be used as a guide could not be identified anywhere and the interdisciplinary perspective that was required was not identified anywhere on the university campus. Students in the class worked on interdisciplinary design projects which culminated in papers and oral presentations. Each of the six design groups consisted of several engineers with different disciplinary roots. The entire course lecture sequence, about 50 hours in all, was videotaped. Discussed here are the authors' experiences in developing the course, including the course syllabus and speaker list.

Rose, W. I.↗

Adaptive wall testing sections (AWTS)

The lecture starts with conventional techniques of minimizing wall interference and explains the principle of wall streamlining. The history of AWTS development is highlighted, along with the benefits of wall streamlining, including minimized boundary interference, increased model size, reduced tunnel drive power, noise, and volume, as well as multiple flow field simulations to be performed using one test section. AWTS-associated problems coming from the need to adjust the test-section boundaries for each test condition are assessed, along with the requirements of a boundary-adjustment strategy. Examples of two- and three-dimensional test sections are presented, and attention is focused on residual interference and the effects of compressibility and model lift on flexible-wall contours.

Wolf, Stephen W. D.↗

Using CLIPS as the cornerstone of a graduate expert systems course

The effective use of the C Language Integrated Production System (CLIPS) as a cornerstone in a graduate expert systems course is described. The course include 8 or 9 hours of in-depth lecturing in CLIPS, as well as a broad coverage of major topics and techniques in expert systems. As part of the requirements of the course, students solved two small yet non-trival problems in CLIPS before going on to develop a toy expert system in CLIPS in an incremental manner as the term project. Furthermore, students were required to evaluate CLIPS programs written by their classmates. An anonymous questionnaire at the end of the semester revealed that the students responded very favorably to the course, especially their experience with CLIPS.

Yue, Kwok-Bun↗

Visually Guided Control of Movement

The papers given at an intensive, three-week workshop on visually guided control of movement are presented. The participants were researchers from academia, industry, and government, with backgrounds in visual perception, control theory, and rotorcraft operations. The papers included invited lectures and preliminary reports of research initiated during the workshop. Three major topics are addressed: extraction of environmental structure from motion; perception and control of self motion; and spatial orientation. Each topic is considered from both theoretical and applied perspectives. Implications for control and display are suggested.

Johnson, Walter W.↗

Special Course on Skin Friction Drag Reduction

Lecture notes for the AGARD Fluid Dynamics Panel (FDP) Special Course on 'Skin Friction Drag Reduction' have been assembled in this report. The aim and scope of this course was to provide an overview of the state of the art of current technology programs focused on reducing aircraft drag caused by skin friction. This report provides a review of recent progress in the field of skin friction drag reduction for transport aircraft. It provides a general introduction to the technology and then focuses on two specific aspects of drag reduction: maintaining laminar flow by controlling transition and manipulating the turbulence structure in boundary layers to help reduce skin friction. Technology associated with the use of riblets, LEBU, polymers, additives, etc., is also reviewed.

Advisory Group for Aerospace Research and Developm↗

Overview on Basis and Use of Performance Prediction Methods

The lecture outlines the basic methods of component matching which are central to the prediction of gas turbine performance. Steady state prediction of off-design performance must be done at the beginning of an engine development program, to ensure that the engine can satisfy all the mission requirements. The matching techniques can be extended to predict transient performance, which is essential for controls development and to ensure good engine handling. The large amount of computation required demands the use of computer modelling and the role of modelling in the development program and the basic requirements for performance modelling are described.

H I H Saravanamuttoo↗

Practical considerations in designing the engine cycle

When it is required to define the cycle parameters and calculate the performance of a real engine, there are numerous practical constraints that need to be taken into account. These fall into two main categories: the limitations of available component technologies, and the operational considerations that are dependent on aircraft application. The lecture discusses the main technology limiters and indicates how they are incorporated into the cycle definition process. Operational factors include the extent of the intended flight envelope and range of critical flight conditions for which performance must be assured, and the balance to be struck between minimising fuel consumption, maximising installed power and constraining costs of ownership. Taking these technology and operational influences into account, the basic cycle characteristics and approach to cycle choice are examined for three main classes of aircraft: subsonic transports, military combat aircraft and helicopters.

M G Philpot↗

Engine Performance and Health Monitoring Models Using Steady State and Transient Prediction Methods

This lecture note discusses the role of computer modelling in the design, development, and validation of a performance monitoring system. The basic requirements of an engine health monitoring system are discussed in the context of the user environment. A form of model based on stage characteristics provides the basis for describing engine measurements. Faults are modelled in accordance with empirical data obtained from tests conducted at the stage level. The model is used to investigate various parameters that provide unambiguous identification of the fault in question. Fault libraries have been developed for field use.

B D MacIsaac↗

Status report, June 1988 - April 1992

The Mars Mission Research Center (MMRC) is one of nine University Space Engineering Research Centers established in June 1988 by NASA's Office of Aeronautics and Space Technology to broaden the nation's engineering capability to meet the critical needs fo the civilian space program. It includes North Carolina State University (NCSU) at Raleigh and on North Carolina A&T State University at Greensboro. The goal of the Center is to focus on research and educational technologies necessary for planetary exploration, especially transportation to and from our moon and Mars. The research combines mission analysis and design, hypersonic aerodynamics, structures and controls, composite materials, and fabrications. Covered here are activities of the Center from June to April 1992. The Center supports 26 graduate students, 29 undergraduates, 27 faculty and 6 staff. An additional 88 undergraduates worked on four special projects. Three facilities at A&T were renovated and a new 7,000 square foot facility was occupied at NCSU in October 1991. Five laboratories have been developed for composite processing and fabrication facility (A&T), materials testing (A&T), weaving (NCSU), braiding (NCSU), and structures (NCSU). During the past two years, the Center added a new dimension to its program - special projects which involve analysis, design, construction, and testing. The first two projects were full-scale research models of a Mars aerobrake and the HL-20 Personnel Launch System. Both projects received considerable new coverage and appeared in national publications. Additional projects include a model of a Mars Exclusion Vehicle, an Orbiter Ejector, and a Remotely Operated Vehicle. The Orbiter Ejector is scheduled to fly on Shuttle Flight STS-47 in October 1992. Special projects have increased undergraduate student participation and provided a mechanism for more interaction between the universities, NASA centers, and industries. The faculty developed 26 new courses related to the activities of the Center. They conducted four workshops on interplanetary spacecraft, lunar/Mars aerobrakes, spacecraft controls, and aerodynamic heating. The Outreach Program developed into a significant component of the Center. Faculty and students have conducted 12 tours of facilities and given 67 lectures to schools (grade k-12) and civic organizations.

Source record↗

On the nature of the interaction between structures and actuators in vibration suppression

This lecture presents a summary of work on the analysis of the interaction between a structure, an actuator used to suppress the vibration of the structure, and the control law implemented by the actuator. Two control applications are considered. First, a proof-mass actuator with experimentally verified dynamics, capable of being used in a space structure configuration is examined. This is connected to a cantilevered beam modeled as a single degree of freedom system. Secondly, an electric motor, again with experimentally verified dynamics, is used to slew a beam modeled by a partial differential equation. Both the experimental and numerical configuration predict the presence of potential instabilities in system performance if proper consideration is not given to interactions between the control law, the structure and the actuator. In addition, an understanding of the interaction is shown to greatly effect performance. In particular it is shown that judicious choice of actuator parameters greatly improves closed loop performance.

Inman, Daniel J.↗

Polarization effects and multipolarization SAR

Imaging radar polarimeters are usually implemented using a Synthetic Aperture Radar (SAR) approach to give a high resolution image in two dimensions: range and azimuth. For each pixel in the image a polarimetric SAR gives sufficient information to characterize the polarimetric scattering properties of the imaged area (or target) as seen by the radar. Using a polarimetric SAR system as opposed to a single-polarization SAR system provides significantly more information about the target scattering mechanisms and allows better discrimination between different types of surfaces. In these notes a brief overview of SAR polarimetry is offered. The notes are intended as a text to accompany a lecture on SAR polarimetry as part of an AGARD-NATO course. Covered in the notes are the following: the polarization properties of electromagnetic waves; the concepts of radar scattering and measuring radar backscatter with a SAR; polarization synthesis; scattering matrix, Stokes matrix, and covariance matrix representations of polarimetric SAR data; polarization signature plots; design and calibration of polarimetric SAR systems; polarization filtering for target detection; fitting a simple model to polarimetric SAR measurements of naturally occurring features; and supervised classification of polarimetric SAR data.

Freeman, Anthony↗

Development of a prototype interactive learning system using multi-media technology for mission independent training program

The Spacelab Mission Independent Training Program provides an overview of payload operations. Most of the training material is currently presented in workbook form with some lecture sessions to supplement selected topics. The goal of this project was to develop a prototype interactive learning system for one of the Mission Independent Training topics to demonstrate how the learning process can be improved by incorporating multi-media technology into an interactive system. This report documents the development process and some of the problems encountered during the analysis, design, and production phases of this system.

Matson, Jack E.↗