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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

The Successful Transfer of Space Derived Convergent Spray Technology(TM): An Application for Industrial Roof Coatings and Interstate Bridge Repair

Although the levels of volatile organic compound (VOC) emissions from industrial roof coatings and paint operations have been reduced in recent years, the roof coating partnership was an effort to further reduce VOC emission levels and to also demonstrate the use of reclaimed automobile tire rubber as a filler material in roof coating systems. Different materials and coatings were evaluated and tested before the final selection was used to coat the roofs of two small buildings at NASA's MSFC (Marshall Space Flight Center) during fiscal year 1997. The primary objective of the Bridge repair partnership was to strategically leverage public and private sector funds for the purpose of developing a bridge repair process that was cheaper, better, and faster than conventional methods. It was also, imperative that this process be environmentally friendly and capable of performing under extreme conditions for a period of not less than 2 years.

McMillan, Vernotto↗
NASA NTRS1997

Off-Line Testing for Bridge Faults in CMOS Domino Logic Circuits

Bridge faults, especially in CMOS circuits, have unique characteristics which make them difficult to detect during testing. This paper presents a technique for detecting bridge faults which have an effect on the output of CMOS Domino logic circuits. The faults are modeled at the transistor level and this technique is based on analyzing the off-set of the function during off-line testing.

Bennett, K.↗
NASA NTRS2003

Simulation, Model Verification and Controls Development of Brayton Cycle PM Alternator: Testing and Simulation of 2 KW PM Generator with Diode Bridge Output

Professor Stankovic will be developing and refining Simulink based models of the PM alternator and comparing the simulation results with experimental measurements taken from the unit. Her first task is to validate the models using the experimental data. Her next task is to develop alternative control techniques for the application of the Brayton Cycle PM Alternator in a nuclear electric propulsion vehicle. The control techniques will be first simulated using the validated models then tried experimentally with hardware available at NASA. Testing and simulation of a 2KW PM synchronous generator with diode bridge output is described. The parameters of a synchronous PM generator have been measured and used in simulation. Test procedures have been developed to verify the PM generator model with diode bridge output. Experimental and simulation results are in excellent agreement.

Anna V Stankovic↗
NASA NTRS2004

From Bridges and Rockets, Lessons for Software Systems

Although differences exist between building software systems and building physical structures such as bridges and rockets, enough similarities exist that software engineers can learn lessons from failures in traditional engineering disciplines. This paper draws lessons from two well-known failures the collapse of the Tacoma Narrows Bridge in 1940 and the destruction of the space shuttle Challenger in 1986 and applies these lessons to software system development. The following specific applications are made: (1) the verification and validation of a software system should not be based on a single method, or a single style of methods; (2) the tendency to embrace the latest fad should be overcome; and (3) the introduction of software control into safety-critical systems should be done cautiously.

Holloway, C. Michael↗
NASA NTRS1987

Geometrical analysis of Cys-Cys bridges in proteins and their prediction from incomplete structural information

Analysis of C-alpha atom positions from cysteines involved in disulphide bridges in protein crystals shows that their geometric characteristics are unique with respect to other Cys-Cys, non-bridging pairs. They may be used for predicting disulphide connections in incompletely determined protein structures, such as low resolution crystallography or theoretical folding experiments. The basic unit for analysis and prediction is the 3 x 3 distance matrix for Cx positions of residues (i - 1), Cys(i), (i +1) with (j - 1), Cys(j), (j + 1). In each of its columns, row and diagonal vector--outer distances are larger than the central distance. This analysis is compared with some analytical models.

NASA Discipline Exobiology↗
NASA NTRS1992

Precision bridge circuit using a temperature sensor

A precision bridge measurement circuit connected to a current source providing a linear output voltage versus resistance change of a variable resistance (resistance temperature transducer) including a voltage follower in one branch of the bridge so that the zero setting of the transducer resistance does not depend upon the current source or upon an excitation voltage. The zero setting depends only on the precision and stability of the three resistances. By connecting the output of an instrumentation amplifier to a feedback resistor and then to the output of the voltage follower, minor nonlinearities in the resistance-vs-temperature output of a resistance-temperature transducer, such as a platinum temperature sensor, may be corrected. Sensors which have nonlinearity opposite in polarity to platinum, such as nickel-iron sensors, may be linearized by inserting an inverting amplifier into the feedback loop.

Mount, Bruce E.↗
NASA NTRS2004

Mass flow sensor utilizing a resistance bridge

A mass flow sensor to be mounted within a duct and measures the mass flow of a fluid stream moving through the duct. The sensor is an elongated thin quartz substrate having a plurality of platinum strips extending in a parallel relationship on the strip, with certain of the strips being resistors connected to an excitation voltage. The resistors form the legs of a Wheatstone bridge. The resistors are spaced a sufficient distance inwardly from the leading and trailing edges of the substrate to lie within the velocity recovery region so that the measured flow is the same as the actual upstream flow. The resistor strips extend at least half-way through the fluid stream to include a substantial part of the velocity profile of the stream. Certain of the resistors detect a change in temperature as the fluid stream moves across the substrate to provide an output signal from the Wheatstone bridge which is representative of the fluid flow. A heater is located in the midst of the resistor array to heat the air as it passes over the array.

Fralick, Gustave C.↗
NASA NTRS1989

Cascaded resonant bridge converters

A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

Stuart, Thomas A.↗
NASA NTRSDate not supplied

Bridging Current Indirect and Future Direct Estimates of Convective Mass Flux Toward Quantifying the Role of Convective Cores on Anvil Area Time Tendencies

Anvil cloud spatial extent is strongly driven by convective mass flux. However, the lack of convective mass flux observations precludes global analyses of the functional relationship between anvil cloud area growth tendencies and convective areal coverage and vertical mass flux. Partly informed by analyses of a hierarchy of WRF mesoscale convective system (MCS) simulations, in this presentation, we discuss new work on estimating convective mass flux by way of an approach that casts the problem of quantifying convective mass flux into terms related to diabatic heating vertical structure, convective area and tropospheric stability. We demonstrate the usefulness of this approach at the MCS spatial scale via development of a simple, robust model that analytically connects system-scale convective mass flux and anvil cloud area growth rates. We show that the model predicts anvil area size changes in agreement with those observed in a global convective system tracking database (TOOCAN). An additional advantage of this approach for estimating convective mass flux is that it bridges future satellite mission plans for directly observing convective mass flux (e.g., AOS) with longer-record observations made by TRMM, GPM and satellite sounder mission data (the latter used for estimating stability) that, when combined, can be used for inferring convective mass fluxes at the MCS spatial scale spanning slowly changing, diverse environments. An evaluation and bridging of both direct and indirect approaches supports convective process analyses varying over longer time periods in this “era of convection.”

convective mass flux↗
NASA NTRSDate not supplied

Bridging current indirect and future direct estimates of convective mass flux toward quantifying the role of convective cores on anvil area time tendencies

Anvil cloud spatial extent is strongly driven by convective mass flux. However, the lack of convective mass flux observations precludes global analyses of the functional relationship between anvil cloud area growth tendencies and convective areal coverage and vertical mass flux. Partly informed by analyses of a hierarchy of WRF mesoscale convective system (MCS) simulations, in this presentation, we discuss new work on estimating convective mass flux by way of an approach that casts the problem of quantifying convective mass flux into terms related to diabatic heating vertical structure, convective area and tropospheric stability. We demonstrate the usefulness of this approach at the MCS spatial scale via development of a simple, robust model that analytically connects system-scale convective mass flux and anvil cloud area growth rates. We show that the model predicts anvil area size changes in agreement with those observed in a global convective system tracking database (TOOCAN). An additional advantage of this approach for estimating convective mass flux is that it bridges future satellite mission plans for directly observing convective mass flux (e.g., AOS) with longer-record observations made by TRMM, GPM and satellite sounder mission data (the latter used for estimating stability) that, when combined, can be used for inferring convective mass fluxes at the MCS spatial scale spanning slowly changing, diverse environments. An evaluation and bridging of both direct and indirect approaches supports convective process analyses varying over longer time periods in this “era of convection.”

convective mass flux↗
NASA NTRSDate not supplied

Sustainable Crop Cultivation in Space Analogs: A BRIDGES Methodology Perspective Through SpaCEA

Sustainable crop cultivation in space holds paramount significance for the support of life in future long-duration missions. This research explores the development and integration of innovative low-cost proof-of-concept (LC-POC) plant growth cabinets tailored for use in space analog missions. By outlining past and current efforts in space farming, this study introduces the SpaCEA Cabinet using BRIDGES framework, establishing a context for reproducible experiments and innovation in plant growth systems. The SpaCEA cabinets can either be delivered in flat packs or assembled on-site, employing cutting-edge methods like 3-D printing and laser cutting. The main objective is to assess how effectively these structures foster crop growth within analog environments while replicating conditions crucial for space exploration. Employing a multi-faceted approach encompassing technical and qualitative dimensions, this project integrates a qualitative investigation where representatives managing analog stations and analog astronauts will partake in interviews and questionnaires to discern specific requirements and challenges within these environments. Insights gained from these engagements will significantly define the final design parameters of updated SpaCEA plant growth cabinets. The practical applicability of these cabinets emphasizes ease of assembly and transportation, addressing the inherent spatial and logistical constraints associated with space missions. Furthermore, the BRIDGES framework ensures the standardization of hardware, software, and data-gathering elements within a unified structure, which utilizes cutting-edge manufacturing technologies for the prototyping and deployment of these cabinets. The anticipated outcomes of this research include the identification of key design considerations and technical specifications for plant growth cabinets tailored to space farming analog systems. This research is poised to contribute valuable knowledge to sustainable space exploration through the development of interoperable plant growth systems for analog environments, advancing research in space crop cultivation which will make up part of a larger bioregenerative life support system.

Advanced Life Support↗
NASA NTRSDate not supplied

Sustainable Crop Cultivation in Space Analogs: A BRIDGES Methodology Perspective Through SpaCEA

Sustainable crop cultivation in space holds paramount significance for the support of life in future long-duration missions. This research explores the development and integration of innovative low-cost proof-of-concept (LC-POC) plant growth cabinets tailored for use in space analog missions. By outlining past and current efforts in space farming, this study introduces the SpaCEA Cabinet using BRIDGES framework, establishing a context for reproducible experiments and innovation in plant growth systems. The SpaCEA cabinets can either be delivered in flat packs or assembled on-site, employing cutting-edge methods like 3-D printing and laser cutting. The main objective is to assess how effectively these structures foster crop growth within analog environments while replicating conditions crucial for space exploration. Employing a multi-faceted approach encompassing technical and qualitative dimensions, this project integrates a qualitative investigation where representatives managing analog stations and analog astronauts will partake in interviews and questionnaires to discern specific requirements and challenges within these environments. Insights gained from these engagements will significantly define the final design parameters of updated SpaCEA plant growth cabinets. The practical applicability of these cabinets emphasizes ease of assembly and transportation, addressing the inherent spatial and logistical constraints associated with space missions. Furthermore, the BRIDGES framework ensures the standardization of hardware, software, and data-gathering elements within a unified structure, which utilizes cutting-edge manufacturing technologies for the prototyping and deployment of these cabinets. The anticipated outcomes of this research include the identification of key design considerations and technical specifications for plant growth cabinets tailored to space farming analog systems. This research is poised to contribute valuable knowledge to sustainable space exploration through the development of interoperable plant growth systems for analog environments, advancing research in space crop cultivation which will make up part of a larger bioregenerative life support system.

Advanced Life Support↗
NASA NTRS2020

Compass Final Report: Venus Bridge Orbiter and Surface Study (V-BOSS)

The Venus Bridge Orbiter and Surface Study (V-BOSS) Compass concurrent engineering design team study shows that new, high-priority Venus science can be achieved using a linked Orbiter + Surface Element (Lander) mission concept within a $200M cost cap with assumptions. This is feasible through optimizing investment in early technologies and platforms, such as the Long-Lived In-Situ Solar System Explorer (LLISSE), leveraging known and flight-ready technology, and the overall use of simple, small, robust systems in innovative approaches to Venus exploration. This architecture allows a range of science investigations through modification of Orbiter-Lander platforms in this study through choice of other instruments (often sensors), science themes, or operational modes. In particular, a fundamental strength of this approach is to provide science not available in other ways by using simplified architectures including rugged systems operable in-situ on the Venus surface. Such investigations would be pathfinders for more complex, and more expensive, future missions. Additionally, the results of this study can be used to further champion the need, value and return of early investment technology programs for the hard problem of in-situ investigations at Venus.

Venus Bridge↗