SEARCH · Engineering Papers

Results for “Paper”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66

All sources NASA NTRS DOE OSTI

NASA NTRS1992

Mission description and in-flight operations of ERBE instruments on ERBS, NOAA 9, and NOAA 10 spacecraft

Instruments of the Earth Radiation Budget Experiment (ERBE) are operating on three different Earth-orbiting spacecraft. The Earth Radiation Budget Satellite (ERBS) is operated by NASA, and NOAA 9 and NOAA 10 weather satellites are operated by the National Oceanic and Atmospheric Administration (NOAA). This paper is the second in a series that describes the ERBE mission, and data processing and validation procedures. This paper describes the spacecraft and instrument operations for the second full year of in-orbit operations, which extend from February 1986 through January 1987. Validation and archival of radiation measurements made by ERBE instruments during this second year of operation were completed in July 1991. This period includes the only time, November 1986 through January 1987, during which all ERBE instruments aboard the ERBE, NOAA 9, and NOAA 10 spacecraft were simultaneously operational. This paper covers normal and special operations of the spacecraft and instruments, operational anomalies, and the responses of the instruments to in-orbit and seasonal variations in the solar environment.

Weaver, William L.↗

NASA NTRS1992

Hypertext and hypermedia systems in information retrieval

This paper opens with a brief history of hypertext and hypermedia in the context of information management during the 'information age.' Relevant terms are defined and the approach of the paper is explained. Linear and hypermedia information access methods are contrasted. A discussion of hyperprogramming in the handling of complex scientific and technical information follows. A selection of innovative hypermedia systems is discussed. An analysis of the Clinical Practice Library of Medicine NASA STI Program hypermedia application is presented. The paper concludes with a discussion of the NASA STI Program's future hypermedia project plans.

Kaye, K. M.↗

NASA NTRS1992

Further improvements in program to calculate electronic properties of narrow band gap materials

The tasks that we have accomplished are discussed. An extra task was a calculation comparing electron mobilities in Mercury Manganese Telluride with Mercury Cadmium Telluride given in 1H. We then list the reports and papers produced and follow that with either abstracts or the papers themselves. In one key paper we obtain good results between experiment and theory in Mercury Zinc Telluride and also find it typically has mobilities competitive with Mercury Cadmium Telluride. In the Appendix we have a relatively complete set of references.

Patterson, James D.↗

NASA NTRS1991

Rotorcraft airframe structural optimization for combined vibration and fatigue constraints

This paper addresses the application of a formal optimization technique in rotorcraft airframe structural design studies to reduce the structural weight, to lower airframe vibrations, and to enhance fatigue life of the structure. Vibration and fatigue considerations in airframe design are described. An optimization methodology based on the use of a nonlinear programming technique to size airframe structural members subjected to constraints on weight, vibration response and fatigue stresses under dynamic loads, are described. The paper focuses on the development of necessary computational tools for airframe structural optimization and describes the sensitivity analysis procedure for these types of design constraints. Further, the paper describes the optimization procedure as implemented in a computer code called DYNOPT which is a unique operational combination of several newly developed Fortran codes as well as modification of existing codes consisting of the direct matrix abstraction modules of the MSC/NASTRAN Program and CONMIN optimizer. The application of the optimization procedure is demonstrated using an elastic-line model of the Bell AH-1G helicopter airframe structure and computational results are discussed.

Sareen, Ashish K.↗

NASA NTRS1991

Operational support considerations in Space Shuttle prelaunch processing

This paper presents an overview of operational support for Space Shuttle payload processing at the John F. Kennedy Space Center. The paper begins with a discussion of the Shuttle payload processing operation itself. It discusses the major organizational roles and describes the two major classes of payload operations: Spacelab mission payload and vertically-installed payload operations. The paper continues by describing the Launch Site Support Team and the Payload Processing Test Team. Specific areas of operational support are then identified including security and access, training, transport and handling, documentation and scheduling. Specific references for further investigatgion are included.

Schuiling, Roelof L.↗

NASA NTRS1991

Rapid design of gravity assist trajectories

Several International Solar-Terrestrial Physics (ISTP) missions require the design of complex gravity-assisted trajectories in order to investigate the interaction of the solar wind with the earth's magnetic field. These trajectories present a formidable trajectory design and optimization problem. This paper discusses the philosophy and methodology that enable an analyst to design and analyze such trajectories. The authors describe what is called 'floating end-point' targeting, which allows the inherently nonlinear multiple body problem to be solved with simple linear techniques. This paper demonstrates how floating end-point targeting combines analytic approximations with a Newton method targeter to achieve trajectory design goals quickly, even for the very sensitive double lunar swingby trajectories used by the ISTP missions. A Multiconic orbit integration scheme allows fast and accurate orbit propagation. This paper also describes a prototype software tool, Swingby, which has been built for trajectory design and launch window analysis.

Carrico, J.↗

NASA NTRS1992

Algorithms for real-time fault detection of the Space Shuttle Main Engine

This paper reports on the results of a program to develop and demonstrate concepts related to a realtime health management system (HMS) for the Space Shuttle Main Engine (SSME). An HMS framework was developed on the basis of a top-down analysis of the current rocket engine failure modes and the engine monitoring requirements. One result of Phase I of this program was the identification of algorithmic approaches for detecting failures of the SSME. Three different analytical techniques were developed which demonstrated the capability to detect failures significantly earlier than the existing redlines. Based on promising initial results, Phase II of the program was initiated to further validate and refine the fault detection strategy on a large data base of 140 SSME test firings, and implement the resultant algorithms in real time. The paper begins with an overview of the refined algorithms used to detect failures during SSME start-up and main-stage operation. Results of testing these algorithms on a data base of nominal and off-nominal SSME test firings is discussed. The paper concludes with a discussion of the performance of the algorithms operating on a real-time computer system.

Ruiz, C. A.↗

NASA NTRS1992

The formation of magnetic cavities in comets

In this paper a unidimensional model for the formation of magnetic cavities in comets is presented. This model includes ion-neutral friction, dissociative recombination, photoionization, and thermal energetic ion pressure coupled with a nonconstant velocity profile which was chosen to simulate the flow pattern. The model explains the thermal ion population profile. Conditions under which a cavity may not form are discussed. In the paper the roles of the various processes are studied, and it is shown that focusing on ion-neutral friction as the major process in the creation of the cavity is not in general correct. In the last part of the paper, the limitations of the model are delineated.

Klopman, Z.↗

NASA NTRS1992

Optimization methods for passive damper placement and tuning

The effectiveness of viscous elements in introducing damping in a structure is a function of several variables, including their number, their location in the structure, and their physical properties. In this paper several optimization problems are posed to optimize these variables. The paper investigates various metrics to define the optimization problem, and compares the damping profiles that are obtained. Both discrete and continuous optimization problems are formulated and solved, corresponding, respectively, to the problems of placement of damping elements and to the tuning of their parameters. The paper particularly emphasizes techniques to make feasible the large scale problems resulting from the optimization formulations. Numerical results involving a lightly damped tested structure are presented.

Milman, M. H.↗

NASA NTRS1993

More Uses For Configuration Control Of Robots

Two papers present theoretical studies of older and newer uses for configuration control. Configuration control described in "Increasing the Dexterity of Redundant Robots" (NPO-17801) and "Redundant Robot Can Avoid Obstacles" (NPO-17852). One paper "Configuration Control of 7 DOF Arms" reviews these concepts, then applies them to commercial robotic arm having seven revolute joints corresponding to those of human arm. Other paper "New Goals for Redundancy Resolution Using Configuration Control" addresses use of redundant degrees of freedom to optimize dynamical instead of kinematical aspects of performance.

Seraji, Homayoun↗

NASA NTRS1992

Mission Control Center enhancement opportunities in the 1990's

The purpose of this paper is to present a framework for understanding the major enhancement opportunities for Air Force Mission Control Center/Test Support Centers (MCC's/TSC's) in the 1990's. Much of this paper is based on the findings of Study 232 and work currently underway in Study 2-6 for the Air Force Systems Command, Space System Division, Network Program Office. In this paper, we will address MCC/TSC enhancement needs primarily from the operator perspective, in terms of the increased capabilities required to improve space operations task performance.

Hartman, Wayne↗

NASA NTRS1992

A monitor for the laboratory evaluation of control integrity in digital control systems operating in harsh electromagnetic environments

This paper presents a strategy for dynamically monitoring digital controllers in the laboratory for susceptibility to electromagnetic disturbances that compromise control integrity. The integrity of digital control systems operating in harsh electromagnetic environments can be compromised by upsets caused by induced transient electrical signals. Digital system upset is a functional error mode that involves no component damage, can occur simultaneously in all channels of a redundant control computer, and is software dependent. The motivation for this work is the need to develop tools and techniques that can be used in the laboratory to validate and/or certify critical aircraft controllers operating in electromagnetically adverse environments that result from lightning, high-intensity radiated fields (HIRF), and nuclear electromagnetic pulses (NEMP). The detection strategy presented in this paper provides dynamic monitoring of a given control computer for degraded functional integrity resulting from redundancy management errors, control calculation errors, and control correctness/effectiveness errors. In particular, this paper discusses the use of Kalman filtering, data fusion, and statistical decision theory in monitoring a given digital controller for control calculation errors.

Belcastro, Celeste M.↗

NASA NTRS1990

Myths and legends in learning classification rules

This paper is a discussion of machine learning theory on empirically learning classification rules. The paper proposes six myths in the machine learning community that address issues of bias, learning as search, computational learning theory, Occam's razor, 'universal' learning algorithms, and interactive learnings. Some of the problems raised are also addressed from a Bayesian perspective. The paper concludes by suggesting questions that machine learning researchers should be addressing both theoretically and experimentally.

Buntine, Wray↗

NASA NTRS1992

The Fourth Annual Thermal and Fluids Analysis Workshop

The Fourth Annual Thermal and Fluids Analysis Workshop was held from August 17-21, 1992, at NASA Lewis Research Center. The workshop consisted of classes, vendor demonstrations, and paper sessions. The classes and vendor demonstrations provided participants with the information on widely used tools for thermal and fluids analysis. The paper sessions provided a forum for the exchange of information and ideas among thermal and fluids analysts. Paper topics included advances and uses of established thermal and fluids computer codes (such as SINDA and TRASYS) as well as unique modeling techniques and applications.

Source record↗

NASA NTRS1992

The environmental control and life-support system for a lunar base: What drives its design

The purpose of this paper is to identify and briefly discuss some of the ground rules and mission scenario details that become drivers of the environmental control and life support (ECLS) system design and of the logistics related to the design. This paper is written for mission planners and non-ECLS system engineers to inform them of the details that will be important to the ECLS engineer when the design phase is reached. In addition, examples illustrate the impact of some selected mission characteristics on the logistics associated with ECLS systems. The last section of this paper focuses on the ECLS system technology development sequence and highlights specific portions that need emphasis.

Hypes, Warren D.↗

NASA NTRS1992

Drilling and Digging Techniques for the Early Lunar Outpost

The theme of this workshop is lunar resource assessment. Topics include identification, quantification, and location of useful elements on and below the lunar surface. The objective of this paper is to look at another side of the issue--how to remove soil from the stiff lunar-soil matrix once useful deposits are located. The goal of this paper is to cause those who think that digging or excavating on the Moon is a trivial problem to rethink the reasons for their opinions. Another goal is to encourage them to view total reliance upon terrestrial heuristics with suspicion. This paper will focus primarily upon digging.

Boles, Walter W.↗

NASA NTRS1992

Astronomy on the Moon: Geological considerations

The Moon is an excellent site for astronomical observations. This paper describes two geological aspects related to astronomy from the Moon. First it evaluates the sources of gases near a lunar base as input to calculations reported in a separate paper on the growth of an artificial lunar atmosphere. The results suggest that mining for He-3 could produce the most gas (1 kg/sec), but rocket exhaust (0.1 kg/sec) and habitat venting (0.5 kg/sec) are also important. Second, the paper discusses criteria that need to be considered when determining the site of a lunar astronomical facility. These are longitude and latitude (equatorial sites are favored), topography (important to be relatively flat for ease of installation), distance from a lunar base (to be free of seismic noise, dust, and gases), the site's value to lunar geoscience (other factors being equal, a geologically diverse site is better), and its value as a materials resource (mining and observatories are incompatible).

Taylor, G. Jeffrey↗

NASA NTRS1992

Microgravity ignition experiment

The purpose of this project is to develop a flight ready apparatus of the microgravity ignition experiment for the GASCan 2 program. This involved redesigning, testing, and making final modifications to the existing apparatus. The microgravity ignition experiment is intended to test the effect of microgravity on the time to ignition of a sample of alpha-cellulose paper. An infrared heat lamp is used to heat the paper sample within a sealed canister. The interior of the canister was redesigned to increase stability and minimize conductive heat transfer to the sample. This design was fabricated and tested and a heat transfer model of the paper sample was developed.

Motevalli, Vahid↗