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At least 1,279 records · Page 71
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NASA NTRS1996

Remote Monitor Alarm System

A remote monitor alarm system monitors discrete alarm and analog power supply voltage conditions at remotely located communications terminal equipment. A central monitoring unit (CMU) is connected via serial data links to each of a plurality of remote terminal units (RTUS) that monitor the alarm and power supply conditions of the remote terminal equipment. Each RTU can monitor and store condition information of both discrete alarm points and analog power supply voltage points in its associated communications terminal equipment. The stored alarm information is periodically transmitted to the CMU in response to sequential polling of the RTUS. The number of monitored alarm inputs and permissible voltage ranges for the analog inputs can be remotely configured at the CMU and downloaded into programmable memory at each RTU. The CMU includes a video display, a hard disk memory, a line printer and an audio alarm for communicating and storing the alarm information received from each RTU.

Stute, Robert A.↗
NASA NTRS1992

Towards an Effective Theory of Reformulation: Semantics - Part 1

This paper describes an investigation into the structure of representations of sets of actions, utilizing semigroup theory. The goals of this project are twofold: to shed light on the relationship between tasks and representations, leading to a classification of tasks according to the representations they admit; and to develop techniques for automatically transforming representations so as to improve problem-solving performance. A method is demonstrated for automatically generating serial algorithms for representations whose actions form a finite group. This method is then extended to representations whose actions form a finite inverse semigroup.

Benjamin, D. Paul↗
NASA NTRS1996

Trabecular Bone Mechanical Properties and Fractal Dimension

Countermeasures for reducing bone loss and muscle atrophy due to extended exposure to the microgravity environment of space are continuing to be developed and improved. An important component of this effort is finite element modeling of the lower extremity and spinal column. These models will permit analysis and evaluation specific to each individual and thereby provide more efficient and effective exercise protocols. Inflight countermeasures and post-flight rehabilitation can then be customized and targeted on a case-by-case basis. Recent Summer Faculty Fellowship participants have focused upon finite element mesh generation, muscle force estimation, and fractal calculations of trabecular bone microstructure. Methods have been developed for generating the three-dimensional geometry of the femur from serial section magnetic resonance images (MRI). The use of MRI as an imaging modality avoids excessive exposure to radiation associated with X-ray based methods. These images can also detect trabecular bone microstructure and architecture. The goal of the current research is to determine the degree to which the fractal dimension of trabecular architecture can be used to predict the mechanical properties of trabecular bone tissue. The elastic modulus and the ultimate strength (or strain) can then be estimated from non-invasive, non-radiating imaging and incorporated into the finite element models to more accurately represent the bone tissue of each individual of interest. Trabecular bone specimens from the proximal tibia are being studied in this first phase of the work. Detailed protocols and procedures have been developed for carrying test specimens through all of the steps of a multi-faceted test program. The test program begins with MRI and X-ray imaging of the whole bones before excising a smaller workpiece from the proximal tibia region. High resolution MRI scans are then made and the piece further cut into slabs (roughly 1 cm thick). The slabs are X-rayed again and also scanned using dual-energy X-ray absorptiometry (DEXA). Cube specimens are then cut from the slabs and tested mechanically in compression. Correlations between mechanical properties and fractal dimension will then be examined to assess and quantify the predictive capability of the fractal calculations.

Hogan, Harry A.↗
NASA NTRS1995

AIAA spacecraft GN&C interface standards initiative: Overview

The American Institute of Aeronautics and Astronautics (AIAA) has undertaken an important standards initiative in the area of spacecraft guidance, navigation, and control (GN&C) subsystem interfaces. The objective of this effort is to establish standards that will promote interchangeability of major GN&C components, thus enabling substantially lower spacecraft development costs. Although initiated by developers of conventional spacecraft GN&C, it is anticipated that interface standards will also be of value in reducing the development costs of micro-engineered spacecraft. The standardization targets are specifically limited to interfaces only, including information (i.e. data and signal), power, mechanical, thermal, and environmental interfaces between various GN&C components and between GN&C subsystems and other subsystems. The current emphasis is on information interfaces between various hardware elements (e.g., between star trackers and flight computers). The poster presentation will briefly describe the program, including the mechanics and schedule, and will publicize the technical products as they exist at the time of the conference. In particular, the rationale for the adoption of the AS1773 fiber-optic serial data bus and the status of data interface standards at the application layer will be presented.

Challoner, A. Dorian↗
NASA NTRS1995

A Microinstrumentation System for Remote Environmental Monitoring

This paper reports on a hybrid micro-instrumentation system that includes a embedded micro-controller, transducers for monitoring environmental parameters, interface/readout electronics for linking the controller and the transducers, and custom circuitry for system power management. Sensors for measuring temperature, pressure, humidity, and acceleration are included in the initial system, which operates for more than 180 days and dissipates less than 700 microW from a 6V battery supply. The sensor scan rate is adaptive and can be event triggered. The system communicates internally over a 1 MHz, nine-line intramodule sensor bus and outputs data over a hard-wired serial interface or a 315MHz wireless link. The use of folding platform packaging allows an internal system volume as small as 5 cc.

Mason, Andrew↗
NASA NTRS1996

Aerodynamic Shape Optimization of Supersonic Aircraft Configurations via an Adjoint Formulation on Parallel Computers

This work describes the application of a control theory-based aerodynamic shape optimization method to the problem of supersonic aircraft design. The design process is greatly accelerated through the use of both control theory and a parallel implementation on distributed memory computers. Control theory is employed to derive the adjoint differential equations whose solution allows for the evaluation of design gradient information at a fraction of the computational cost required by previous design methods. The resulting problem is then implemented on parallel distributed memory architectures using a domain decomposition approach, an optimized communication schedule, and the MPI (Message Passing Interface) Standard for portability and efficiency. The final result achieves very rapid aerodynamic design based on higher order computational fluid dynamics methods (CFD). In our earlier studies, the serial implementation of this design method was shown to be effective for the optimization of airfoils, wings, wing-bodies, and complex aircraft configurations using both the potential equation and the Euler equations. In our most recent paper, the Euler method was extended to treat complete aircraft configurations via a new multiblock implementation. Furthermore, during the same conference, we also presented preliminary results demonstrating that this basic methodology could be ported to distributed memory parallel computing architectures. In this paper, our concern will be to demonstrate that the combined power of these new technologies can be used routinely in an industrial design environment by applying it to the case study of the design of typical supersonic transport configurations. A particular difficulty of this test case is posed by the propulsion/airframe integration.

Reuther, James↗
NASA NTRS1996

STS-72 Space Shuttle Mission Report

The STS-72 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-fourth flight of the Space Shuttle Program, the forty-ninth flight since the return-to-flight, and the tenth flight of the Orbiter Endeavour (OV-105). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-75; three Block I SSME's that were designated as serial numbers 2028, 2039, and 2036 in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-077. The RSRM's, designated RSRM-52, were installed in each SRB and the individual RSRM's were designated as 36OW052A for the left SRB, and 36OW052B for the right SRB. Appendix A lists the sources of data, both formal and informal, that were used to prepare this report. The primary objectives of this flight were to retrieve the Japanese Space Flyer Unit (JSFU) and deploy and retrieve the Office of Aeronautics and Space Technology-Flyer (OAST-Flyer). Secondary objectives were to perform the operations of the Shuttle Solar Backscatter Ultraviolet (SSBUV/A) experiment, Shuttle Laser Altimeter (SLA)/get-Away Special (GAS) payload, Physiological and Anatomical Rodent Experiment/National Institutes of Health-Cells (STL/NIH-C) experiment, Protein Crystal Growth-Single Locker Thermal Enclosure System (PCG-STES) experiment, Commercial Protein Crystal Growth (CPCG) payload and perform two extravehicular activities (EVA's) to demonstrate International Space Station Alpha (ISSA) assembly techniques). Appendix B provides the definition of acronyms and abbreviations used throughout the report. All times during the flight are given in Greenwich mean time (GMT) and mission elapsed time (MET).

Fricke, Robert W., Jr.↗
NASA NTRS1995

STS-69 Space Shuttle Mission Report

The STS-69 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-first flight of the Space Shuttle Program, the forty-sixth flight since the return-to-flight, and the ninth flight of the Orbiter Endeavour(OV-105). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-72; three SSME's that were designated as serial numbers 2035, 2109, and 2029 in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-074. The RSRMS, designated RSRM-44, were installed in each SRB and the individual RSRM's were designated as 36OL048A for the left SRB, and 36OW048B for the right SRB. The primary objectives of this flight were to perform the operations necessary to fulfill the requirments of Wake Shield Facility (WSF) and SPARTAN-201. The secondary objectives were to perform the operation of the International Extreme Ultraviolet Hitchhiker (IEH-1), the Capillary Pumped Loop-2/GAS Bridge Assembly (CAPL-2/GBA), Thermal Energy Storage (TES), Auroral Photography Experiment-B (APE-B) and the Extravehicular Activity (EVA) Development Flight Test 02 (EDFT-02), the Biological Research in Canister (BRIC) payload, the Commercial Generic Bioprocessing Apparatus (CGBA) payload, the Electrolysis Performance Improvement Concept Study (EPICS) payload, the Space Tissue Loss, National Institute of Health-Cells (STL/NIH-CS) payload, and the Commercial Middeck Instrumentation Technology Associates Experiment (CMIX). Appendix A lists the sources of data, both formal and informal, that were used to prepare this report. Appendix B provides the definition of acronyms and abbreviations used throughout the report. All times during the flight are given in Greenwich mean time (GMT) and mission elapsed time (MET).

Fricke, Robert W., Jr.↗
NASA NTRS1996

STS-75 Space Shuttle Mission Report

The STS-75 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-fifth flight of the Space Shuttle Program, the fiftieth flight since the return-to-flight, and the nineteenth flight of the Orbiter Columbia (OV-102). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-76; three SSME's that were designated as serial numbers 2029, 2034, and 2017 in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-078. The RSRM's, designated RSRM-53, were installed in each SRB and the individual RSRMs were designated as 36OW53A for the left SRB, and 36OW053B for the right SRB. The primary objectives of this flight were to perform the operations necessary to fulfill the requirements of the Tethered Satellite System-1 R (TSS-1R), and the United States Microgravity Payload-3 (USMP-3). The secondary objectives were to complete the operations of the Orbital Acceleration Research Experiment (OARE), and to meet the requirements of the Middeck Glovebox (MGBX) facility and the Commercial Protein Crystal Growth (CPCG) experiment. Appendix A provides the definition of acronyms and abbreviations used thorughout the report. All times during the flight are given in Greenwich mean time (GMT) and mission elapsed time (MET).

Fricke, Robert W., Jr.↗
NASA NTRS1996

STS-76 Space Shuttle Mission Report

The STS-76 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-sixth flight of the Space Shuttle Program, the fifty-first flight since the return-to-flight, and the sixteenth flight of the Orbiter Atlantis (OV-104). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-77; three SSME's that were designated as serial numbers 2035, 2109, and 2019 in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-079. The RSRM's, designated RSRM-46, were installed in each SRB and the individual RSRM's were designated as 360TO46A for the left SRB, and 360TO46B for the right SRB. The primary objectives of this flight were to rendezvous and dock with the Mir Space Station and transfer one U.S. Astronaut to the Mir. A single Spacehab module carried science equipment and hardware, Risk Mitigation Experiments (RME's), and Russian Logistics in support of the Phase 1 Program requirements. In addition, the European Space Agency (ESA) Biorack operations were performed. Appendix A lists the sources of data, both formal and informal, that were used to prepare this report. Appendix B provides the definition of acronyms and abbreviations used throughout the report. All times during the flight are given in Greenwich mean time (GMT) and mission elapsed time (MET).

Fricke, Robert W., Jr.↗
NASA NTRS1995

STS-73 Space Shuttle Mission Report

The STS-73 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-second flight of the Space Shuttle Program, the forty-seventh flight since the return-to-flight, and the eighteenth flight of the Orbiter Columbia (OV-102). STS-73 was also the first flight of OV-102 following the vehicle's return from the Orbiter Maintenance Down Period (OMDP). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-73; three SSME's that were designated as serial numbers 2037 (Block 1), 2031 (PH-1), and 2038 (Block 1) in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-075. The RSRM's, designated RSRM-50, were installed in each SRB and the individual RSRM's were designated as 36OL050A for the left SRB, and 36OW050B for the right SRB. The primary objective of this flight was to successfully perform the planned operations of the United States Microgravity Laboratory (USML)-2 payload.

Fricke, Robert W., Jr.↗
NASA NTRS1996

STS-74 Space Shuttle Mission Report

The STS-74 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-third flight of the Space Shuttle Program, the forty-eighth flight since the return-to-flight, and the fifteenth flight of the Orbiter Atlantis (OV-104). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-74; three Phase 11 SSME's that were designated as serial numbers 2012, 2026, and 2032 in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-076. The RSRM's, designated RSRM-51, were installed in each SRB and the individual RSRM's were designated as 360TO51 A for the left SRB, and 360TO51 B for the right SRB. The primary objectives of this flight were to rendezvous and dock with the Mir Space Station and perform life sciences investigations. The Russian Docking Module (DM) was berthed onto the Orbiter Docking System (ODS) using the Remote Manipulator System (RMS), and the Orbiter docked to the Mir with the DM. When separating from the Mir, the Orbiter undocked, leaving the DM attached to the Mir. The two solar arrays, mounted on the DM, were delivered for future Russian installation to the Mir. The secondary objectives of the flight were to perform the operations necessary to fulfill the requirements of the GLO experiment (GLO-4)/Photogrammetric Appendage Structural Dynamics Experiment Payload (PASDE) (GPP), the IMAX Cargo Bay Camera (ICBC), and the Shuttle Amateur Radio Experiment-2 (SAREX-2). Appendix A lists the sources of data, both formal and informal, that were used to prepare this report. Appendix B provides the definition of acronyms and abbreviations used throughout the report. All times during the flight are given in Greenwich mean time (GMT)) and mission elapsed time (MET).

Fricke, Robert W., Jr.↗
NASA NTRS1995

Implementation of Remote Acquisition and Storage System

The existing system for gathering and processing acoustical test data had several shortcomings and limitations in the areas of microphone array size, sampling rate, and background noise. A new Remote Acquisition and Storage System (RASS) is being designed for applications not suited for the existing acquisition system. One of the first tasks in the design of the RASS was to redesign the microprocessor card of the existing system to include RS-232 serial ports to accept communications through the radio modem used in the RF link. Cost and parts availability comparisons were made between the newly designed board and commercially available models, and a commercially made model was selected. This model was tested for basic I/0 operations. The prototype of the RF telemetry system was set up and tested. Plans are now being developed for integrating the RF telemetry system with the other RASS subsystems.

Hess, Jason R.↗
NASA NTRS1996

Effects of Sustained Low-Level Elevations of Carbon Dioxide on Cerebral Blood Flow and Autoregulation of the Intracerebral Arteries in Humans

Cerebral blood flow velocity (CBFv) was measured by insonating the middle cerebral arteries of 4 subjects using a 2 Mhz transcranial Doppler. Ambient CO2 was elevated to 0.7% for 23 days in the first study and to 1.2% for 23 days in the same subjects in the second study. By non-parametric testing CBFv was elevated significantly by +35% above pre-exposure levels during the first 1-3 days at both exposure levels after which CBFv progressively readjusted to pre-exposure levels. Despite similar CBFv responses, headache was only reported during the initial phase of exposure to 1.2% CO2. Vascular reactivity to CO2 assessed by rebreathing showed a similar pattern with the CBFv increases early in the exposures being greater than those elicited later. An increase in metabolic rate of the visual cortex was evoked by having the subjects open and close their eyes during a visual stimulus. Evoked CBFv responses measured in the posterior cerebral artery were also elevated in the first 1-3 days of both studies returning to pre-exposure levels as hypercapnia continued. Cerebral vascular autoregulation assessed by raising head pressure during 10 deg head-down tilt both during the low-level exposures and during rebreathing was unaltered. There were no changes in the retinal microcirculation during serial fundoscopy studies. The time-dependent changes in CO2 vascular reactivity might be due either to retention of bicarbonate in brain extracellular fluid or to progressive increases in ventilation, or both. Cerebral vascular autoregulation appears preserved during chronic exposure to these levels of ambient CO2.

Sliwka, U.↗
NASA NTRS1996

Multigrid with Overlapping Patches

Solving boundary value problems with optimal efficiency requires adaptivity and multilevel techniques. Previously, an implementation of the AFACx algorithm is presented that is based on rectangular Cartesian grids. This implementation does not allow for the over]ap of grids that lie on the same level of refinement. We investigate the case in which these grids overlap. A standard technique for overlapping grids is the Schwarz algorithm. Some ways of using the Schwarz algorithm in a standard multigrid scheme are presented. Also, a problem that arises in some situations with non-aligned, overlapping grids is described. This situation comes up in a natural way when the Schwarz algorithm is used as a relaxation scheme within a multilevel algorithm. We identify the reason for the bad convergence and show that by more sophisticated interpolation the difficulties can be overcome. Then we present a multiplicative Schwarz algorithm for a large number of grids that has a high potential for parallelization. Finally we give some numerical results for the FACx algorithm with overlapping grids on each refinement level. The implementation of the described codes uses C++ and the array class libraries A++ and P++. Using the A++/P++ programming environment, it was possible to move from a serial code to a parallel code within a few days.

Berndt, Markus↗
NASA NTRS1996

Design and Implementation of Replicated Object Layer

One of the widely used techniques for construction of fault tolerant applications is the replication of resources so that if one copy fails sufficient copies may still remain operational to allow the application to continue to function. This thesis involves the design and implementation of an object oriented framework for replicating data on multiple sites and across different platforms. Our approach, called the Replicated Object Layer (ROL) provides a mechanism for consistent replication of data over dynamic networks. ROL uses the Reliable Multicast Protocol (RMP) as a communication protocol that provides for reliable delivery, serialization and fault tolerance. Besides providing type registration, this layer facilitates distributed atomic transactions on replicated data. A novel algorithm called the RMP Commit Protocol, which commits transactions efficiently in reliable multicast environment is presented. ROL provides recovery procedures to ensure that site and communication failures do not corrupt persistent data, and male the system fault tolerant to network partitions. ROL will facilitate building distributed fault tolerant applications by performing the burdensome details of replica consistency operations, and making it completely transparent to the application.Replicated databases are a major class of applications which could be built on top of ROL.

Koka, Sudhir↗
NASA NTRS1996

Aerodynamic Shape Optimization of Supersonic Aircraft Configurations via an Adjoint Formulation on Parallel Computers

This work describes the application of a control theory-based aerodynamic shape optimization method to the problem of supersonic aircraft design. The design process is greatly accelerated through the use of both control theory and a parallel implementation on distributed memory computers. Control theory is employed to derive the adjoint differential equations whose solution allows for the evaluation of design gradient information at a fraction of the computational cost required by previous design methods (13, 12, 44, 38). The resulting problem is then implemented on parallel distributed memory architectures using a domain decomposition approach, an optimized communication schedule, and the MPI (Message Passing Interface) Standard for portability and efficiency. The final result achieves very rapid aerodynamic design based on higher order computational fluid dynamics methods (CFD). In our earlier studies, the serial implementation of this design method (19, 20, 21, 23, 39, 25, 40, 41, 42, 43, 9) was shown to be effective for the optimization of airfoils, wings, wing-bodies, and complex aircraft configurations using both the potential equation and the Euler equations (39, 25). In our most recent paper, the Euler method was extended to treat complete aircraft configurations via a new multiblock implementation. Furthermore, during the same conference, we also presented preliminary results demonstrating that the basic methodology could be ported to distributed memory parallel computing architectures [241. In this paper, our concem will be to demonstrate that the combined power of these new technologies can be used routinely in an industrial design environment by applying it to the case study of the design of typical supersonic transport configurations. A particular difficulty of this test case is posed by the propulsion/airframe integration.

Reuther, James↗
NASA NTRS1993

Morphological Changes in Rat Vestibular System Following Weightlessness

Mammalian gravity receptors (maculas) are morphologically organized for weighted, parallel distributed processing of information. There are two basic circuits: 1) highly channeled, type I cell to calyx; and 2) distributed modifying, type II cells to calyces and processes. The latter circuit should be the more adaptable since it modifies final output. To test this hypothesis, rats were flown in microgravity for 9 days aboard a space shuttle and euthanized shortly after landing. Hair cells and ribbon synapses from maculas of 3 flight and 3 ground control rats were studied ultrastructurally in blocks of 50 serial sections. Synapses increased by approximately 41% in type I cells and by approximately 55% in type II cells in flight animals. There was a shift toward the spherular form of ribbon synapse in both types of hair cells in flight animals. Current findings tend to support the stated hypothesis and indicate that mature utricular hair cells retain synaptic plasticity, permitting adaptation to an altered gravitational environment.

Ross, Muriel D.↗