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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.

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NASA NTRS1992

Update of GRASP/Ada reverse engineering tools for Ada

The GRASP/Ada project (Graphical Representations of Algorithms, Structures, and Processes for Ada) has successfully created and prototyped a new algorithmic level graphical representation of Ada software, the Control Structure Diagram (CSD). The primary impetus for creation of the CSD was to improve the comprehension efficiency of Ada software and, as a result, improve reliability and reduce costs. The emphasis was on the automatic generation of the CSD from Ada PDL or source code to support reverse engineering and maintenance. The CSD has the potential to replace traditional prettyprinted Ada source code. In Phase 1 of the GRASP/Ada project, the CSD graphical constructs were created and applied manually to several small Ada programs. A prototype (Version 1) was designed and implemented using FLEX and BISON running under VMS on a VAS 11-780. In Phase 2, the prototype was improved and ported to the Sun 4 platform under UNIX. A user interface was designed and partially implemented using the HP widget toolkit and the X Windows System. In Phase 3, the user interface was extensively reworked using the Athena widget toolkit and X Windows. The prototype was applied successfully to numerous Ada programs ranging in size from several hundred to several thousand lines of source code. Following Phase 3, the prototype was evaluated by software engineering students at Auburn University and then updated with significant enhancements to the user interface including editing capabilities. Version 3.2 of the prototype was prepared for limited distribution to facilitate further evaluation. The current prototype provides the capability for the user to generate CSD's from Ada PDL or source code in a reverse engineering as well as forward engineering mode with a level of flexibility suitable for practical application.

Cross, James H., II↗
NASA NTRS1993

Retrievable payload carrier, next generation Long Duration Exposure Facility: Update 1992

Access to space and cost have been two major inhibitors of low Earth orbit research. The Retrievable Payload Carrier (RPC) Program is a commercial space program which strives to overcome these two barriers to space experimentation. The RPC Program's fleet of spacecraft, ground communications station, payload processing facility, and experienced integration and operations team will provide a convenient 'one-stop shop' for investigators seeking to use the unique vantage point and environment of low Earth orbit for research. The RPC is a regularly launched and retrieved, free-flying spacecraft providing resources adequate to meet modest payload/experiment requirements, and presenting ample surface area, volume, mass, and growth capacity for investigator usage. Enhanced capabilities of ground communications, solar-array-supplied electrical power, central computing, and on-board data storage pick up on the path where NASA's Long Duration Exposure Facility (LDEF) blazed the original technology trail. Mission lengths of 6-18 months, or longer, are envisioned. The year 1992 was designated as the 'International Space Year' and coincides with the 500th anniversary of Christopher Columbus's voyage to the New World. This is a fitting year in which to launch the full scale development of our unique shop of discovery whose intent is to facilitate retrieving technological rewards from another new world: space. Presented is an update on progress made on the RPC Program's development since the November 1991 LDEF Materials Workshop.

Perry, A. T.↗
NASA NTRS1992

Update to the safety program for the general-purpose heat source radioisotope thermoelectric generators for the Galileo and Ulysses missions

With the rescheduling of the Galileo and Ulysses launches and the use of new upper stages following the Challenger accident, the aerospace nuclear safety program for the general-purpose heat source radioisotope thermoelectric generators (GPHS-RTGs) was extended to accommodate the new mission scenarios. As in the original safety program, the objectives were to determine the response of the GPHS-RTG to the various postulated accident environments and to determine the risk (if any) associated with these postulated accidents. The extended GPHS-RTG safety program was successfully completed in sufficient time to prepare an updated Final Safety Analysis Report (FSAR) with revisions for the October 1989 launch of the Galileo spacecraft.

Bennett, Gary L.↗
NASA NTRS1992

Applications of multiple-constraint matrix updates to the optimal control of large structures

Low-authority control or vibration suppression in large, flexible space structures can be formulated as a linear feedback control problem requiring computation of displacement and velocity feedback gain matrices. To ensure stability in the uncontrolled modes, these gain matrices must be symmetric and positive definite. In this paper, efficient computation of symmetric, positive-definite feedback gain matrices is accomplished through the use of multiple-constraint matrix update techniques originally developed for structural identification applications. Two systems were used to illustrate the application: a simple spring-mass system and a planar truss. From these demonstrations, use of this multiple-constraint technique is seen to provide a straightforward approach for computing the low-authority gains.

Smith, S. W.↗
NASA NTRS1993

Model updating based on sensitivities of system matrices

A new approach, which allows the physical parameters to be adjusted and preserves the structural connectivity condition, is developed in this paper. This approach is based on the sensitivities of the mass and stiffness matrices with respect to physical parameters in an attempt to use test data to correct the analytical model. The analytical mass and stiffness matrices can be corrected simultaneously. The modal data of the updated model dramatically converges to that of the test model. A numerical example is presented to illustrate the feasibility of this approach. Comparisons with the other methods are also given.

Huang, Hsin-Hsen↗
NASA NTRS1992

The Tropical Rainfall Measuring Mission (TRMM) update and its role in EOS and GEWEX

Updated information is presented on the U.S./Japan Tropical Rainfall Measuring Mission (TRMM), which is a relatively low-budget earth-probe satellite with a secondary objective of measuring upwelling radiation from the clouds and the surfaces below the satellite. Particular attention is given to the TRMM rain measurements and the characteristics of the three TRMM rain measuring instruments: the microwave radiometer, the radar, and the visible/IR radiometer. Also discussed are the TRMM contributions to EOS and GEWEX.

Simpson, Joanne↗
NASA NTRS1991

Update on the NASA ER-2 Doppler radar system (EDOP)

An update on the development status of EDOP, a dual-beam Doppler weather radar to be flown on the NASA ER-2 aircraft, is presented. The EDOP system is an X-band Doppler radar with a dual-beam configuration in the ER-2 nose, such that one beam is nadir pointing and the other at an angle of 35 deg forward of the nadir. The dual beams, as used on ELDORA, directed at, e.g., 20 deg fore and aft of the normal to the fuselage, require only a linear rather than L-shaped flight pattern to compute air motions. On the ER-2, EDOP will essentially map out high-resolution time-height sections of reflectivity and vertical hydrometeor velocity from the nadir beam. Flying EDOP with other ground-based and airborne radars will also provide a more complete picture of the overall 3D precipitation and hydrometeor structure of storms.

Heymsfield, Gerald M.↗
NASA NTRS1993

Updating finite element dynamic models using an element-by-element sensitivity methodology

A sensitivity-based methodology for improving the finite element model of a given structure using test modal data and a few sensors is presented. The proposed method searches for both the location and sources of the mass and stiffness errors and does not interfere with the theory behind the finite element model while correcting these errors. The updating algorithm is derived from the unconstrained minimization of the squared L sub 2 norms of the modal dynamic residuals via an iterative two-step staggered procedure. At each iteration, the measured mode shapes are first expanded assuming that the model is error free, then the model parameters are corrected assuming that the expanded mode shapes are exact. The numerical algorithm is implemented in an element-by-element fashion and is capable of 'zooming' on the detected error locations. Several simulation examples which demonstate the potential of the proposed methodology are discussed.

Farhat, Charbel↗
NASA NTRS1992

The effect of initial imperfections on shell stability: An updated review

The development of the Delft Interactive Shell Design Code (DISDECO) is described. The purpose is to make the accumulated theoretical, numerical, and practical knowledge of the last years readily accessible to users interested in the analysis of buckling sensitive structures. With this open ended, hierarchical, interactive computer code, the user can access workstation programs of increasing complexity. As a first update of DISDECO, the computational modules of the initial level were modified so as to handle combined loads consisting of axial compression, internal and external pressure, and clockwise or counter clockwise torque. The applied load is assumed to have a uniform spatial distribution and is divided into a fixed and a variable part. The magnitude of the variable part is allowed to vary in proportion to a load parameter Lambda. This leads to an eigenvalue problem for the critical lambda sub C.

Arbocz, J.↗
NASA NTRS1993

Automating a human factors evaluation of graphical user interfaces for NASA applications: An update on CHIMES

Capturing human factors knowledge about the design of graphical user interfaces (GUI's) and applying this knowledge on-line are the primary objectives of the Computer-Human Interaction Models (CHIMES) project. The current CHIMES prototype is designed to check a GUI's compliance with industry-standard guidelines, general human factors guidelines, and human factors recommendations on color usage. Following the evaluation, CHIMES presents human factors feedback and advice to the GUI designer. The paper describes the approach to modeling human factors guidelines, the system architecture, a new method developed to convert quantitative RGB primaries into qualitative color representations, and the potential for integrating CHIMES with user interface management systems (UIMS). Both the conceptual approach and its implementation are discussed. This paper updates the presentation on CHIMES at the first International Symposium on Ground Data Systems for Spacecraft Control.

Jiang, Jian-Ping↗
NASA NTRS1994

CET93 and CETPC: An interim updated version of the NASA Lewis computer program for calculating complex chemical equilibria with applications

The NASA Lewis chemical equilibrium program with applications continues to be improved and updated. The latest version is CET93. This code, with smaller arrays, has been compiled for use on an IBM or IBM-compatible personal computer and is called CETPC. This report is intended to be primarily a users manual for CET93 and CETPC. It does not repeat the more complete documentation of earlier reports on the equilibrium program. Most of the discussion covers input and output files, two new options (ONLY and comments), example problems, and implementation of CETPC.

Mcbride, Bonnie J.↗
NASA NTRS1994

A review of an updated synthesis of noise/annoyance relationships

This report evaluates the evidence supporting the 'dosage-effect relationship for the prevalence of annoyance due to general transportation noise' that was originally presented in 1978 and more recently updated in 1991. The synthesis methods and many of the constituent studies' reports are examined. The weaknesses of the synthesis are identified and found to be partly due to the synthesis methodology, but fundamentally to the lack of comparability in the constituent studies' methodologies and reporting procedures. Several suggested improvements to survey, analysis, and synthesis techniques are proposed.

Fields, James M.↗
NASA NTRS1994

National Educators' Workshop: Update 1993. Standard Experiments in Engineering Materials Science and Technology

This document contains a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 93 held at the NASA Langley Research Center in Hampton, Virginia, on November 3-5, 1993. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community.

Gardner, James E.↗
NASA NTRS1994

Update to the NASA Lewis Ice Accretion Code LEWICE

This report is intended as an update to NASA CR-185129 'User's Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE).' It describes modifications and improvements made to this code as well as changes to the input and output files, interactive input, and graphics output. The comparison of this code to experimental data is shown to have improved as a result of these modifications.

Wright, William B.↗
NASA NTRS1995

LDEF environment modeling updates

An updated gas dynamics model for gas interactions around the LDEF is presented that includes improved scattering algorithms. The primary improvement is more accurate predictions of surface fluxes in the wake region. The code used is the Integrated Spacecraft Environments Model (ISEM). Additionally, initial results of a detailed ISEM prediction model of the Solar Array Passive LDEF Experiment (SAMPLE), A0171, is presented. This model includes details of the A0171 geometry and outgassing characteristics of the many surfaces on the experiment. The detailed model includes the multiple scattering that exists between the ambient atmosphere, LDEF outgassing, and atomic oxygen erosion products. Predictions are made for gas densities, surface fluxes and deposition at three different time periods of the LDEF mission.

Gordon, Tim↗
NASA NTRS1993

A proposed update to the solar irradiance spectrum used in LOWTRAN and MODTRAN

The calibrated upwelling radiance spectra measured by AVIRIS are increasingly being analyzed with radiative transfer codes. Analysis of AVIRIS data with the LOWTRAN and MODTRAN radiative transfer codes has led to indications of an error in the solar irradiance spectra used by these codes. This paper presents evidence for the error and proposed update to the solar irradiance spectra used by LOWTRAN and MODTRAN.

Green, Robert O.↗
NASA NTRS1995

Microgravity Combustion Science: 1995 Program Update

Microgravity greatly benefits the study of fundamental combustion processes. In this environment, buoyancy-induced flow is nearly eliminated, weak or normally obscured forces and flows can be isolated, gravitational settling or sedimentation is nearly eliminated, and temporal and spatial scales can be expanded. This document reviews the state of knowledge in microgravity combustion science with the emphasis on NASA-sponsored developments in the current period of 1992 to early 1995. The subjects cover basic research in gaseous premixed and diffusion-flame systems, flame structure and sooting, liquid droplets and pools, and solid-surface ignition and flame spread. They also cover applied research in combustion synthesis of ceramic-metal composites, advanced diagnostic instrumentation, and on-orbit fire safety. The review promotes continuing research by describing the opportunities for Principal Investigator participation through the NASA Research Announcement program and the available NASA Lewis Research Center ground-based facilities and spaceflight accommodations. This review is compiled by the members and associates of the NASA Lewis Microgravity Combustion Branch, and it serves as an update of two previous overview reports.

Ross, Howard D.↗