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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 811 records · Page 45

All sources NASA NTRS DOE OSTI

NASA NTRS2007

Scientific Verification Test of Orbitec Deployable Vegetable Production System for Salad Crop Growth on ISS- Gas Exchange System design and function

The ability to produce and maintain salad crops during long term missions would be a great benefit to NASA; the renewable food supply would save cargo space, weight and money. The ambient conditions of previous ground controlled crop plant experiments do not reflect the microgravity and high CO2 concentrations present during orbit. It has been established that microgravity does not considerably alter plant growth. (Monje, Stutte, Chapman, 2005). To support plants in a space-craft environment efficient and effective lighting and containment units are necessary. Three lighting systems were previously evaluated for radish growth in ambient air; fluorescent lamps in an Orbitec Biomass Production System Educational (BPSE), a combination of red, blue, and green LED's in a Deployable Vegetable Production System (Veggie), and a combination of red and blue LED's in a Veggie. When mass measurements compared the entire possible growing area vs. power consumed by the respective units, the Veggies clearly exceeded the BPSE indicating that the LED units were a more resource efficient means of growing radishes under ambient conditions in comparison with fluorescent lighting. To evaluate the most productive light treatment system for a long term space mission a more closely simulated ISS environment is necessary. To induce a CO2 dense atmosphere inside the Veggie's and BPSE a gas exchange system has been developed to maintain a range of 1000-1200 ppm CO2 during a 21-day light treatment experiment. This report details the design and function of the gas exchange system. The rehabilitation, trouble shooting, maintenance and testing of the gas exchange system have been my major assignments. I have also contributed to the planting, daily measurements and harvesting of the radish crops 21-day light treatment verification test.

Eldemire, Ashleigh↗

NASA NTRS2004

Implementation of ALARA radiation protection on the ISS through polyethylene shielding augmentation of the Service Module Crew Quarters

With 5-7 month long duration missions at 51.6 degrees inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the "as low as reasonably achievable" (ALARA) precept requires that radiological risks be minimized when possible through a dose optimization process. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. Polyethylene (CnHn) is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Results of the studies shown herein indicate that 20% or more reduction in equivalent dose to the CQ occupant is achievable. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Center JSC↗

NASA NTRS1977

Fabrication and verification testing of ETM 30 cm diameter ion thrusters

Engineering model designs and acceptance tests are described for the 800 and 900 series 30 cm electron bombardment thrustors. Modifications to the test console for a 1000 hr verification test were made. The 10,000 hr endurance test of the S/N 701 thruster is described, and post test analysis results are included.

Collett, C.↗

NASA NTRS1972

Investigation of optical/infrared sensor techniques for application satellites

A method of scanning an optical sensor array by acoustic surface waves is discussed. Data cover detailed computer based analysis of the operation of a multielement acoustic surface-wave-scanned optical sensor, the development of design and operation techniques that were used to show the feasibility of an integrated array to design several such arrays, and experimental verification of a number of the calculations with discrete sensor devices.

Kaufman, I.↗

NASA NTRS1978

Air-liquid solar collector for solar heating, combined heating and cooling, and hot water subsystems

A collection of quarterly reports consisting of the installation and layout design of the air collector system for commercial applications, completion of the preliminary design review, detailed design efforts, and preparation of the verification test plan are given. Performance specifications and performance testing of a prototype model of a two manifold, 144 tube air collector array is presented.

Source record↗

NASA NTRS1978

Advanced rotorcraft technology: Task force report

The technological needs and opportunities related to future civil and military rotorcraft were determined and a program plan for NASA research which was responsive to the needs and opportunities was prepared. In general, the program plan places the primary emphasis on design methodology where the development and verification of analytical methods is built upon a sound data base. The four advanced rotorcraft technology elements identified are aerodynamics and structures, flight control and avionic systems, propulsion, and vehicle configurations. Estimates of the total funding levels that would be required to support the proposed program plan are included.

Source record↗

NASA NTRS1981

Aerodynamics/ACEE: Aircraft energy efficiency

An overview is presented of a 10 year program managed by NASA which seeks to make possible the most efficient use of energy for aircraft propulsion and lift as well as provide a technology that can be used by U.S. manufacturers of air transports and engines. Supercritical wings, winglets, vortex drag reduction, high lift, active control, laminar flow control, and aerodynamics by computer are among the topics discussed. Wind tunnel models in flight verification of advanced technology, and the design, construction and testing of various aircraft structures are also described.

Source record↗

NASA NTRS1983

Software Specification Language

SSL translator aids in developing and checking software systems. Goal of SSL is to provide form of verification and consistency checking early in design phase. Serves as formal document to communicate software architecure to detailed designers.

Buckles, B. P.↗

NASA NTRS1982

A digital flight control system verification laboratory

A NASA/FAA program has been established for the verification and validation of digital flight control systems (DFCS), with the primary objective being the development and analysis of automated verification tools. In order to enhance the capabilities, effectiveness, and ease of using the test environment, software verification tools can be applied. Tool design includes a static analyzer, an assertion generator, a symbolic executor, a dynamic analysis instrument, and an automated documentation generator. Static and dynamic tools are integrated with error detection capabilities, resulting in a facility which analyzes a representative testbed of DFCS software. Future investigations will ensue particularly in the areas of increase in the number of software test tools, and a cost effectiveness assessment.

De Feo, P.↗

NASA NTRS1984

A balloon-borne high-resolution spectrometer for observations of gamma-ray emission from solar flares

The design, development, and balloon-flight verification of a payload for observations of gamma-ray emission from solar flares are reported. The payload incorporates a high-purity germanium semiconductor detector, standard NIM and CAMAC electronics modules, a thermally stabilized pressure housing, and regulated battery power supplies. The flight system is supported on the ground with interactive data-handling equipment comprised of similar electronics hardware. The modularity and flexibility of the payload, together with the resolution and stability obtained throughout a 30-hour flight, make it readily adaptable for high-sensitivity, long-duration balloon fight applications.

Crannell, C. J.↗

NASA NTRS1986

Testing certifies the Space Shuttle Main Engine life improvement modifications

Development and certification tests have been conducted on the Space Shuttle Main Engine to verify design changes made on the high-pressure turbopumps to expand operating margin at full-power level, increase life, and reduce maintenance requirements. Design changes are summarized and the verification process is described in detail. Methods of testing turbopumps for increased rotor stability, reduced bearing loads, extended bearing and turbine blade life, and reduced turbine operating temperatures are also described. Accomplishments to date in extending both the power level and life of the SSME are summarized.

Wood, Byron K.↗

NASA NTRS1987

Optimal signal-to-noise in digital phase lock amplifiers

An expression for the optimal signal-to-noise ratio for linear phase lock amplifiers is derived. In its digital form the optimal method can be implemented by real-time signal processing techniques. The case of detector-noise-limited systems is analyzed in detail; it is found that the optimal technique can be used to eliminate effectively the detector's time constant from the set of parameters determining the overall efficiency. This has important implications for optical detection system design. Also reported is an experimental verification of the optimal method, thus establishing its practicality.

Doering, Charles R.↗

NASA NTRS1986

Thermal testing by internal IR heating of the FEP module

A spacecraft module, to be integrated with the FLTSATCOM spacecraft, was tested in a simulated orbit environment separate from the host spacecraft. Thermal vacuum testing of the module was accomplished using internal IR heating rather than conventional external heat sources. For this configuration, the technique produced boundary conditions expected for flight to enable verification of system performance and thermal design details.

Nathanson, D. M.↗

NASA NTRS1990

An expert system for fault diagnosis in a Space Shuttle main engine

The detection and diagnosis of SSME faults in an early stage is important in order to allow enough time for fault preventive or corrective measurements. Since most of the faults in a complex system like SSME develop rapidly, early detection and diagnosis of faults is critical for the survival of space vehicles. An expert system has been designed for automatic learning, detection, identification, verification, and correction of anomalous propulsion system operations. This paper describes an innovative machine learning approach which is employed for the automatic training of this expert system.

Ali, Moonis↗

NASA NTRS1993

Prototype test article verification of the Space Station Freedom active thermal control system microgravity performance

To verify the on-orbit operation of the Space Station Freedom (SSF) two-phase external Active Thermal Control System (ATCS), a test and verification program will be performed prior to flight. The first system level test of the ATCS is the Prototype Test Article (PTA) test that will be performed in early 1994. All ATCS loops will be represented by prototypical components and the line sizes and lengths will be representative of the flight system. In this paper, the SSF ATCS and a portion of its verification process are described. The PTA design and the analytical methods that were used to quantify the gravity effects on PTA operation are detailed. Finally, the gravity effects are listed, and the applicability of the 1-g PTA test results to the validation of on-orbit ATCS operation is discussed.

Chen, I. Y.↗

NASA NTRS1994

Frequency Analysis Of Data On Telerobotic Tasks

Data on forces and torques measured in experiments with remote manipulators processed into spectral signatures via special frequency-analysis procedure. Spectral signatures complement other measures used to evaluate performances of telerobotic systems and human operators. Contributes to verification of some assumptions made in designing manipulator arms and control subsystems and used as feedback by operators engaged in realtime monitoring of telerobotic tasks. Also provides useful indications of flows of power between manipulators and their environments.

Fiorini, Paolo↗

NASA NTRS1993

Formal methods and digital systems validation for airborne systems

This report has been prepared to supplement a forthcoming chapter on formal methods in the FAA Digital Systems Validation Handbook. Its purpose is as follows: to outline the technical basis for formal methods in computer science; to explain the use of formal methods in the specification and verification of software and hardware requirements, designs, and implementations; to identify the benefits, weaknesses, and difficulties in applying these methods to digital systems used on board aircraft; and to suggest factors for consideration when formal methods are offered in support of certification. These latter factors assume the context for software development and assurance described in RTCA document DO-178B, 'Software Considerations in Airborne Systems and Equipment Certification,' Dec. 1992.

Rushby, John↗

NASA NTRS1994

Engineering large-scale agent-based systems with consensus

The paper presents the consensus method for the development of large-scale agent-based systems. Systems can be developed as networks of knowledge based agents (KBA) which engage in a collaborative problem solving effort. The method provides a comprehensive and integrated approach to the development of this type of system. This includes a systematic analysis of user requirements as well as a structured approach to generating a system design which exhibits the desired functionality. There is a direct correspondence between system requirements and design components. The benefits of this approach are that requirements are traceable into design components and code thus facilitating verification. The use of the consensus method with two major test applications showed it to be successful and also provided valuable insight into problems typically associated with the development of large systems.

Bokma, A.↗