SEARCH · Engineering Papers

Results for “Description”

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 1,459 records · Page 81

All sources NASA NTRS DOE OSTI

NASA NTRS1989

The solid surface combustion space shuttle experiment hardware description and ground-based test results

The Lewis Research Center is developing a series of microgravity combustion experiments for the Space Shuttle. The Solid Surface Combustion Experiment (SSCE) is the first to be completed. SSCE will study flame spreading over thermally thin fuels (ashless filter paper) under microgravity conditions. The flight hardware consists of a combustion chamber containing the sample and a computer which takes the data and controls the experiment. Experimental data will include gas-phase and solid-phase temperature measurements and motion pictures of the combustion process. Flame spread rates will be determined from the motion pictures.

Vento, D. M.↗

NASA NTRS1989

Consequences of nonclassical measurement for the algorithmic description of continuous dynamical systems

Continuous dynamical systems intuitively seem capable of more complex behavior than discrete systems. If analyzed in the framework of the traditional theory of computation, a continuous dynamical system with countably many quasistable states has at least the computational power of a universal Turing machine. Such an analysis assumes, however, the classical notion of measurement. If measurement is viewed nonclassically, a continuous dynamical system cannot, even in principle, exhibit behavior that cannot be simulated by a universal Turing machine.

Fields, Chris↗

NASA NTRS1989

On the Lagrangian description of unsteady boundary layer separation. Part 2: The spinning sphere

A theory to explain the initial stages of unsteady separation was proposed by Van Dommelen and Cowley (1989). This theory is verified for the separation process that occurs at the equatorial plane of a sphere or a spheroid which is impulsively spun around an axis of symmetry. A Lagrangian numerical scheme is developed which gives results in good agreement with Eulerian computations, but which is significantly more accurate. This increased accuracy, and a simpler structure to the solution, also allows verification of the Eulerian structure, including the presence of logarithmic terms. Further, while the Eulerian computations broke down at the first occurrence of separation, it is found that the Lagrangian computation can be continued. It is argued that this separated solution does provide useful insight into the further evolution of the separated flow. A remarkable conclusion is that an unseparated vorticity layer at the wall, a familiar feature in unsteady separation processes, disappears in finite time.

Vandommelen, Leon L.↗

NASA NTRS1989

On the Lagrangian description of unsteady boundary layer separation. Part 1: General theory

Although unsteady, high-Reynolds number, laminar boundary layers have conventionally been studied in terms of Eulerian coordinates, a Lagrangian approach may have significant analytical and computational advantages. In Lagrangian coordinates the classical boundary layer equations decouple into a momentum equation for the motion parallel to the boundary, and a hyperbolic continuity equation (essentially a conserved Jacobian) for the motion normal to the boundary. The momentum equations, plus the energy equation if the flow is compressible, can be solved independently of the continuity equation. Unsteady separation occurs when the continuity equation becomes singular as a result of touching characteristics, the condition for which can be expressed in terms of the solution of the momentum equations. The solutions to the momentum and energy equations remain regular. Asymptotic structures for a number of unsteady 3-D separating flows follow and depend on the symmetry properties of the flow. In the absence of any symmetry, the singularity structure just prior to separation is found to be quasi 2-D with a displacement thickness in the form of a crescent shaped ridge. Physically the singularities can be understood in terms of the behavior of a fluid element inside the boundary layer which contracts in a direction parallel to the boundary and expands normal to it, thus forcing the fluid above it to be ejected from the boundary layer.

Vandommelen, Leon L.↗

NASA NTRS1989

BCAUS Project description and consideration of separation of data and control

The commonly stated truths that data may be segregated from program control in generic expert system shells and that such tools support straightforward knowledge representation were examined. The ideal of separation of data from program control in expert systems is difficult to realize for a variety of reasons. One approach to achieving this goal is to integrate hybrid collections of specialized shells and tools instead of producing custom systems built with a single all purpose expert system tool. Aspects of these issues are examined in the context of a specific diagnostic expert system application, the Backup Control Mode Analysis and Utility System (BCAUS), being developed for the Gamma Ray Observatory (GRO) spacecraft. The project and the knowledge gained in working on the project are described.

Bush, Joy L.↗

NASA NTRS1988

Toward a descriptive model of galactic cosmic rays in the heliosphere

Researchers review the elements that enter into phenomenological models of the composition, energy spectra, and the spatial and temporal variations of galactic cosmic rays, including the so-called anomalous cosmic ray component. Starting from an existing model, designed to describe the behavior of cosmic rays in the near-Earth environment, researchers suggest possible updates and improvements to this model, and then propose a quantitative approach for extending such a model into other regions of the heliosphere.

Mewaldt, R. A.↗

NASA NTRS1988

A multidimensional model for aerosols - Description of computational analogs

The numerical algorithms used to simulate the advection, diffusion, sedimentation, coagulation, and condensational growth of atmospheric aerosols are described. The model can be used in one, two, or three spatial dimensions. The continuity equation in a generalized horizontal and vertical coordinate system is developed, which allows the model to be quickly adapted to a wide variety of dynamical models of global or regional scale. Algorithms are developed to treat the various physical processes, and the results of simulations are presented, which show the strengths and weaknesses of these algorithms. Although the emphasis is on the modeling of aerosols, the work is also applicable to the simulations of the transport of gases.

Toon, O. B.↗

NASA NTRS1988

Description of an oscillating flow pressure drop test rig

A test rig designed to generate heat exchanger pressure drop information under oscillating flow conditions is described. This oscillating flow rig is based on a variable stroke and variable frequency linear drive motor. A frequency capability of 120 hertz and a mean test pressure up to 15 mPA (2200 psi) allows for testing at flow conditions found in modern high specific power Stirling engines. An important design feature of this rig is that it utilizes a single close coupled dynamic pressure transducer to measure the pressure drop across the test sample. This eliminates instrumentation difficulties associated with the pressure sensing lines common to differential pressure transducers. Another feature of the rig is that it utilizes a single displacement piston. This allows for testing of different sample lengths and configurations without hardware modifications. All data acquisition and reduction for the rig is performed with a dedicated personal computer. Thus the overall system design efficiently integrates the testing and data reduction procedures. The design methodology and details of the test rig are described.

Wood, J. Gary↗

NASA NTRS1988

Radiative transfer to space through a precipitating cloud at multiple microwave frequencies. I - Model description. II - Results and analysis

The impact of time-dependent cloud microphysical structure on the transfer to space of passive microwave radiation is studied at several frequencies across the EHF and lower SHF portions of the microwave spectrum. The feasibility of using multichannel passive-microwave retrieval techniques to estimate precipitation from space-based platforms is examined. The model is described, and the results are assessed in conjunction with a Nimbus-7 SMMR case study of precipitation in an intense tropical Pacific storm. It is concluded that the effects of cloud liquid water content must be considered to obtain a realistic estimation and distribution of rainrates.

Mugnai, Alberto↗

NASA NTRS1988

Boundary layer dynamics in the description of magnetospheric substorms

This paper presents an analysis of eleven magnetospheric substorm events for which good-quality ground-based magnetometer data and ISEE satellite data were both available. It is shown that the magnetotail particle and field observations associated with a substorm expansive phase can be explained through the spatial movement of the boundary layers and central plasma sheet in the magnetotail. The sweeping of these regions past the satellite, even in the absence of temporal variations within the various regions, can lead to a set of plasma flow observations typical of what is observed in the magnetotail during substorm activity.

Eastman, T. E.↗

NASA NTRS1989

The reusable reentry satellite - A mission and system description and operational concept

A significant need exists for a system which will provide the life science experimenter with relatively frequent and inexpensive access to the space environment. To fulfill this need, a project and spacecraft system described as the Reusable Reentry Satellite (RRS) or LifeSat has been proposed by NASA. The RRS provides a relatively inexpensive method of access to space for extended periods of time and eventual intact recovery of the experiments on the earth's surface. The payload support requirements, flight operations concept are reviewed and the mission and system of the RRS are described in detail.

Swenson, Byron L.↗

NASA NTRS1989

The solid surface combustion Space Shuttle experiment hardware description and ground-based test results

Vento, D. M.↗

NASA NTRS1988

The U.S. Sarsat geosynchronous experiment - Ground processor description and test results

The development of a specialized digital signal processor, the Geosynchronous Signal Processor (GSP), for short beacon burst signal detection and demodulation is described. The processing is based on fast Fourier Transform techniques for detection and message integration on the respective message bursts for demodulation. The GSP is based on array processor technology; it is designed to yield an ultimate capacity of 50-75 simultaneous beacon transmissions within the nominal 20 KHz bandwidth centered at 406.025 MHz.

Flikkema, P. G.↗

NASA NTRS1988

A large scale second generation experiment in multi-version software - Description and early results

The Second-Generation Experiment is a large-scale empirical study of the development and operation of multiversion software systems that has engaged researchers at five universities and three research institutes. This paper presents the history and current status of this experiment. A preliminary analysis of the multiple software versions has been performed and is reported here.

Kelly, John P. J.↗

NASA NTRS1989

Management plan documentation standard and Data Item Descriptions (DID). Volume of the information system life-cycle and documentation standards, volume 2

This is the second of five volumes of the Information System Life-Cycle and Documentation Standards. This volume provides a well-organized, easily used standard for management plans used in acquiring, assuring, and developing information systems and software, hardware, and operational procedures components, and related processes.

Callender, E. David↗

NASA NTRS1989

Assurance specification documentation standard and Data Item Descriptions (DID). Volume of the information system life-cycle and documentation standards, volume 4

This is the fourth of five volumes on Information System Life-Cycle and Documentation Standards. This volume provides a well organized, easily used standard for assurance documentation for information systems and software, hardware, and operational procedures components, and related processes. The specifications are developed in conjunction with the corresponding management plans specifying the assurance activities to be performed.

Callender, E. David↗

NASA NTRS1989

Management control and status reports documentation standard and Data Item Descriptions (DID). Volume of the information system life-cycle and documentation standards, volume 5

This is the fifth of five volumes on Information System Life-Cycle and Documentation Standards. This volume provides a well organized, easily used standard for management control and status reports used in monitoring and controlling the management, development, and assurance of informations systems and software, hardware, and operational procedures components, and related processes.

Callender, E. David↗

NASA NTRS1990

Functional description of a command and control language tutor

The status of an ongoing project to explore the application of Intelligent Tutoring System (ITS) technology to NASA command and control languages is described. The primary objective of the current phase of the project is to develop a user interface for an ITS to assist NASA control center personnel in learning Systems Test and Operations Language (STOL). Although this ITS will be developed for Gamma Ray Observatory operators, it will be designed with sufficient flexibility so that its modules may serve as an ITS for other control languages such as the User Interface Language (UIL). The focus of this phase is to develop at least one other form of STOL representation to complement the operational STOL interface. Such an alternative representation would be adaptively employed during the tutoring session to facilitate the learning process. This is a key feature of this ITS which distinguishes it from a simulator that is only capable of representing the operational environment.

Elke, David R.↗