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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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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

An Overview of Starfish: A Table-Centric Tool for Interactive Synthesis

Engineering is an interactive process that requires intelligent interaction at many levels. My thesis [1] advances an engineering discipline for high-level synthesis and architectural decomposition that integrates perspicuous representation, designer interaction, and mathematical rigor. Starfish, the software prototype for the design method, implements a table-centric transformation system for reorganizing control-dominated system expressions into high-level architectures. Based on the digital design derivation (DDD) system a designer-guided synthesis technique that applies correctness preserving transformations to synchronous data flow specifications expressed as co- recursive stream equations Starfish enhances user interaction and extends the reachable design space by incorporating four innovations: behavior tables, serialization tables, data refinement, and operator retiming. Behavior tables express systems of co-recursive stream equations as a table of guarded signal updates. Developers and users of the DDD system used manually constructed behavior tables to help them decide which transformations to apply and how to specify them. These design exercises produced several formally constructed hardware implementations: the FM9001 microprocessor, an SECD machine for evaluating LISP, and the SchemEngine, garbage collected machine for interpreting a byte-code representation of compiled Scheme programs. Bose and Tuna, two of DDD s developers, have subsequently commercialized the design derivation methodology at Derivation Systems, Inc. (DSI). DSI has formally derived and validated PCI bus interfaces and a Java byte-code processor; they further executed a contract to prototype SPIDER-NASA's ultra-reliable communications bus. To date, most derivations from DDD and DRS have targeted hardware due to its synchronous design paradigm. However, Starfish expressions are independent of the synchronization mechanism; there is no commitment to hardware or globally broadcast clocks. Though software back-ends for design derivation are limited to the DDD stream-interpreter, targeting synchronous or real-time software is not substantively different from targeting hardware.

Tsow, Alex↗
NASA NTRS1987

Development of a coupled expert system for the spacecraft attitude control problem

A majority of the current expert systems focus on the symbolic-oriented logic and inference mechanisms of artificial intelligence (AI). Common rule-based systems employ empirical associations and are not well suited to deal with problems often arising in engineering. Described is a prototype expert system which combines both symbolic and numeric computing. The expert system's configuration is presented and its application to a spacecraft attitude control problem is discussed.

Kawamura, K.↗
NASA NTRS2010

Multi-Evaporator Miniature Loop Heat Pipe for Small Spacecraft Thermal Control: Validation Results - Part 2

Under NASA s New Millennium Program Space Technology 8 (ST 8) Project, Goddard Space Fight Center has conducted a Thermal Loop experiment to advance the maturity of the Thermal Loop technology from proof of concept to prototype demonstration in a relevant environment , i.e. from a technology readiness level (TRL) of 3 to a level of 6. The thermal Loop is an advanced thermal control system consisting of a miniature loop heat pipe (MLHP) with multiple evaporators and multiple condensers designed for future small system applications requiring low mass, low power, and compactness. The MLHP retains all features of state-of-the-art loop heat pipes (LHPs) and offers additional advantages to enhance the functionality, performance, versatility, and reliability of the system. An MLHP breadboard was built and tested in the laboratory and thermal vacuum environments for the TRL 4 and TRL 5 validations, respectively, and an MLHP proto-flight unit was built and tested in a thermal vacuum chamber for the TRL 6 validation. In addition, an analytical model was developed to simulate the steady state and transient behaviors of the MLHP during various validation tests. The MLHP demonstrated excellent performance during experimental tests and the analytical model predictions agreed very well with experimental data. All success criteria at various TRLs were met. Hence, the Thermal Loop technology has reached a TRL of 6. This paper presents the validation results, both experimental and analytical, of such a technology development effort.

Ku, Jentung↗
NASA NTRS2006

AST Critical Propulsion and Noise Reduction Technologies for Future Commercial Subsonic Engines Area of Interest 1.0: Reliable and Affordable Control Systems

The General Electric Reliable and Affordable Controls effort under the NASA Advanced Subsonic Technology (AST) Program has designed, fabricated, and tested advanced controls hardware and software to reduce emissions and improve engine safety and reliability. The original effort consisted of four elements: 1) a Hydraulic Multiplexer; 2) Active Combustor Control; 3) a Variable Displacement Vane Pump (VDVP); and 4) Intelligent Engine Control. The VDVP and Intelligent Engine Control elements were cancelled due to funding constraints and are reported here only to the state they progressed. The Hydraulic Multiplexing element developed and tested a prototype which improves reliability by combining the functionality of up to 16 solenoids and servo-valves into one component with a single electrically powered force motor. The Active Combustor Control element developed intelligent staging and control strategies for low emission combustors. This included development and tests of a Controlled Pressure Fuel Nozzle for fuel sequencing, a Fuel Multiplexer for individual fuel cup metering, and model-based control logic. Both the Hydraulic Multiplexer and Controlled Pressure Fuel Nozzle system were cleared for engine test. The Fuel Multiplexer was cleared for combustor rig test which must be followed by an engine test to achieve full maturation.

Myers, William↗
NASA NTRS1974

MIDAS, prototype Multivariate Interactive Digital Analysis System, phase 1. Volume 1: System description

The MIDAS System is described as a third-generation fast multispectral recognition system able to keep pace with the large quantity and high rates of data acquisition from present and projected sensors. A principal objective of the MIDAS program is to provide a system well interfaced with the human operator and thus to obtain large overall reductions in turnaround time and significant gains in throughput. The hardware and software are described. The system contains a mini-computer to control the various high-speed processing elements in the data path, and a classifier which implements an all-digital prototype multivariate-Gaussian maximum likelihood decision algorithm operating at 200,000 pixels/sec. Sufficient hardware was developed to perform signature extraction from computer-compatible tapes, compute classifier coefficients, control the classifier operation, and diagnose operation.

Kriegler, F. J.↗
NASA NTRS1975

Line Fluid Actuated Valve Development Program

The feasibility of a line-fluid actuated valve design for potential application as a propellant-control valve on the space shuttle was examined. Design and analysis studies of two prototype valve units were conducted and demonstrated performance is reported. It was shown that the line-fluid actuated valve concept offers distinct weight and electrical advantages over alternate valve concepts. Summaries of projected performance and design goals are also included.

Lynch, R. A.↗
NASA NTRS1976

On the status of V/STOL flight

Basic principles relating to the accomplishment of V/STOL flight are reviewed as they pertain to current prototype developments. Particular consideration is given to the jet flap, flow augmentation and circulation control separately and in combination. Configurations as the augmentor wing, upper-surface blown flaps, externally blown flaps and the circulation-controlled rotor are also examined.

Mccormick, B. W.↗
NASA NTRS1979

Numerical simulation of dynamics of brushless dc motors for aerospace and other applications. Volume 1: Model development and applications, part A

The development, fabrication and evaluation of a prototype electromechanical actuator (EMA) is discussed. Application of the EMA as a motor for control surfaces in aerospace flight is examined. A mathematical model of the EMA is developed for design optimization. Nonlinearities which complicate the mathematical model are discussed. The dynamics of the EMA from the underlying physical principles are determined and a discussion of similating the control logic by means of equivalent boolean expressions is presented.

Demerdash, N. A. O.↗
NASA NTRS1980

Chemical vapor deposited tungsten with dispersed carbides for Space Shuttle check valves

A chemical vapor deposited tungsten with dispersed carbides was selected as the material for Space Shuttle Orbital Maneuvering and Reaction Control Systems check valve poppets and seats. The selection followed a NASA-sponsored prototype check valve development program utilizing the cutter-seal shell poppet concept. The poppet material is deposited as a coating approximately 0.9 mm thick and fabricated into a shell as a free standing body. The seat material is deposited as a coating 1.1 mm thick on a seat blank, and the cutter seal is machined in the coating. Module tests demonstrated that the material could be ground and lapped to very sharp edges and could cut through typical system contaminants without excessive damage to the sealing surfaces. The material was also determined to be unaffected by exposure to a strongly oxidizing storable propellant.

Williams, G. E.↗
NASA NTRS1985

State of the art survey of network operating systems development

The results of the State-of-the-Art Survey of Network Operating Systems (NOS) performed for Goddard Space Flight Center are presented. NOS functional characteristics are presented in terms of user communication data migration, job migration, network control, and common functional categories. Products (current or future) as well as research and prototyping efforts are summarized. The NOS products which are revelant to the space station and its activities are evaluated.

Source record↗
NASA NTRS1988

MTK: An AI tool for model-based reasoning

A 1988 goal for the Systems Autonomy Demonstration Project Office of the NASA Ames Research Office is to apply model-based representation and reasoning techniques in a knowledge-based system that will provide monitoring, fault diagnosis, control, and trend analysis of the Space Station Thermal Control System (TCS). A number of issues raised during the development of the first prototype system inspired the design and construction of a model-based reasoning tool called MTK, which was used in the building of the second prototype. These issues are outlined here with examples from the thermal system to highlight the motivating factors behind them, followed by an overview of the capabilities of MTK, which was developed to address these issues in a generic fashion.

Erickson, William K.↗
NASA NTRS1988

Generic supervisor: A knowledge-based tool for control of space station on-board systems

The concept of a generic module for management of onboard systems grew out of the structured analysis effort for the Space Station software. Hierarchical specification of subsystems software revealed that nontrivial supervisory elements are required at all levels. The number of supervisors (and subsequent software) required to implement the hierarchical control over onboard functions comprise a large portion of the Space Station software. Thus, a generic knowledge based supervisory module significantly reduces the amount of software developed. This module, the Generic Supervisor, depends on its knowledge of control to provide direction for subordinates and feedback to superiors within a specific subsystem area. The Generic Supervisor provides an adaptable and maintainable control system. A portion of the Space Station Environmental Control and Life Support System (ECLSS) was implemented as a hierarchy of supervisors. This prototype implementation demonstrates the feasibility of a generic knowledge based supervisor, and its facility to meet complex mission requirements.

Carnes, J. R.↗
NASA NTRS1989

An adiabatic demagnetization refrigerator for SIRTF

An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.

Timbie, P. T.↗
NASA NTRS1992

Transportable Applications Environment Plus

Transportable Applications Environment Plus (TAE+) is integrated, portable program providing environment for developing and running interactive window, text, and graphical object-based application software systems. Enables construction of custom application interface and moving applications to different computers. Components are WorkBench, tool for design of user interface; WPT's (Window Programming Tools) package, set of callable subroutines controlling user interface; and TAE Command Language (TCL), providing ways to develop executable application prototype with run-time-interpreted language. Uses MIT X-Window System, WorkBench and WPT's written in C++, remaining code in C.

Source record↗
NASA NTRS1992

An electrostatically suspended, micro-mechanical rate gyroscope

SatCon Technology has performed a study of micromechanical gyroscopes. The goals of this program were to define a baseline system configuration and establish technical feasibility for proof of principle and prototype fabrication. This report documents the research and presents the baseline mechanical design, sensors, control systems, and electronics. This section presents a project overview and specific technical objectives. Section 2 contains a background on micromechanical technology. Section 3 contains the microgyroscope specifications and configurations. Section 4 contains the electromechanical design. Section 5 outlines the control and electronics. Section 6 presents a preliminary sequence for microfabrication of the baseline design, and Section 7 contains conclusions and recommendations for further work.

Hawkey, Timothy↗
NASA NTRS1993

Robotic System For Greenhouse Or Nursery

Report presents additional information about robotic system described in "Robotic Gripper With Force Control And Optical Sensors" (MFS-28537). "Flexible Agricultural Robotics Manipulator System" (FARMS) serves as prototype of robotic systems intended to enhance productivities of agricultural assembly-line-type facilities in large commercial greenhouses and nurseries.

Gill, Paul↗