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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Laminar flow control perforated wing panel development

Many structural concepts for a wing leading edge laminar flow control hybrid panel were analytically investigated. After many small, medium, and large tests, the selected design was verified. New analytic methods were developed to combine porous titanium sheet bonded to a substructure of fiberglass and carbon/epoxy cloth. At -65 and +160 F test conditions, the critical bond of the porous titanium to the composite failed at lower than anticipated test loads. New cure cycles, design improvements, and test improvements significantly improved the strength and reduced the deflections from thermal and lateral loadings. The wave tolerance limits for turbulence were not exceeded. Consideration of the beam column midbay deflections from the combinations of the axial and lateral loadings and thermal bowing at -65 F, room temperature, and +160 F were included. Many lap shear tests were performed at several cure cycles. Results indicate that sufficient verification was obtained to fabricate a demonstration vehicle.

Fischler, J. E.↗
DOE OSTI2022

Mild-to-wild plastic transition is governed by athermal screw dislocation slip in bcc Nb

Plastic deformation in crystals is mediated by the motion of line defects known as dislocations. For decades, dislocation activity has been treated as a homogeneous, smooth continuous process. However, it is now recognized that plasticity can be determined by long-range correlated and intermittent collective dislocation processes, known as avalanches. Here we demonstrate in body-centered cubic Nb how the long-range and scale-free dynamics at room temperature are progressively quenched out with decreasing temperature, eventually revealing intermittency with a characteristic length scale that approaches the Burgers vector itself. Plasticity is shown to be bimodal across the studied temperature regime, with conventional thermally-activated smooth plastic flow (‘mild’) coexisting with sporadic bursts (‘wild’) controlled by athermal screw dislocation activity, thereby violating the classical notion of temperature-dependent screw dislocation motion at low temperatures. An abrupt increase of the athermal avalanche component is identified at the critical temperature of the material. Our results indicate that plasticity at any scale can be understood in terms of the coexistence of these mild and wild modes of deformation, which could help design better alloys by suppressing one of the two modes in desired temperature windows.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Room temperature doping of Ln 3+ in perovskite nanoparticles: a halide exchange mediated cation exchange approach

This study presents a halide exchange mediated cation exchange strategy for a room temperature doping of trivalent lanthanide cations (Ln 3+ ) in cesium lead halide (CsPbX 3 ) nanoparticles (NPs). Post-synthetic addition of LnCl 3 [Ln = Nd, Sm, Eu, Tb, Dy, and Yb] to a solution of CsPbBr 3 NPs generates the corresponding lanthanide doped NPs which display host sensitized Ln 3+ emission. Structural and spectroscopic characterizations indicate a successful halide exchange and substitutional displacement of Pb 2+ by Ln 3+ . The effect of halide identity in controlling the Ln 3+ sensitization was also evaluated. Here, a photophysical framework is presented that can be used to predict the Ln 3+ sensitization in perovskite NPs semiempirically, thereby removing the constraints of trial and error in designing a perovskite NP-Ln 3+ host–guest combination.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

Constitutive Models for the Viscoelastic Behavior of Polyimide Membranes at Room and Deep Cryogenic Temperatures

Targets for ICF shots on NIF typically use ~500nm thin polyimide films with a coating of 25nm of aluminum as windows that seal the laser entrance hole or LEH. Their role is to contain the hohlraum gas and minimize the extraneous infra-red radiation getting in. This is necessary to precisely control the hohlraum thermal environment for layering inside the capsule with solid deuterium-tritium at 18K. Here, we use our empirical data on the bulging behavior of these foils under various different conditions to develop models to capture the complex viscoelastic behavior of these films at both ambient and cryogenic temperatures. The constitutive equations derived from these models give us the ability to quantitatively specify the film’s behavior during the fielding of these targets and set the best parameters for new target designs.

36 MATERIALS SCIENCE↗
NASA NTRS2017

Computational Modeling to Limit the Impact Displays and Indicator Lights Have on Habitable Volume Operational Lighting Constraints

NASA has demonstrated an interest in improving astronaut health and performance through the installment of a new lighting countermeasure on the International Space Station. The Solid State Lighting Assembly (SSLA) system is designed to positively influence astronaut health by providing a daily change to light spectrum to improve circadian entrainment. Unfortunately, existing NASA standards and requirements define ambient light level requirements for crew sleep and other tasks, yet the number of light-emitting diode (LED) indicators and displays within a habitable volume is currently uncontrolled. Because each of these light sources has its own unique spectral properties, the additive lighting environment ends up becoming something different from what was planned or researched. Restricting the use of displays and indicators is not a solution because these systems provide beneficial feedback to the crew. The research team for this grant used computer-based computational modeling and real-world lighting mockups to document the impact that light sources other than the ambient lighting system contribute to the ambient spectral lighting environment. In particular, the team was focused on understanding the impacts of long-term tasks located in front of avionics or computer displays. The team also wanted to understand options for mitigating the changes to the ambient light spectrum in the interest of maintaining the performance of a lighting countermeasure. The project utilized a variety of physical and computer-based simulations to determine direct relationships between system implementation and light spectrum. Using real-world data, computer models were built in the commercially available optics analysis software Zemax Optics Studio(c). The team also built a mockup test facility that had the same volume and configuration as one of the Zemax models. The team collected over 1200 spectral irradiance measurements, each representing a different configuration of the mockup. Analysis of the data showed a measurable impact on ambient light spectrum. This data showed that obvious design techniques exist that can be used to bind the ambient light spectrum closer to the planned spectral operating environment for the observer's eye point. The following observations should be considered when designing an operational environment that is dominated by computer displays. When more light is directed into the field of view of the observer, the greater the impact it will make on various human factors issues that depend on spectral shape and intensity. Because viewing angle has a large part to play in the amount of light flux on the crewmember's retina, beam shape, combined with light source location is an important factor for determining percent probable incident flux on the observer from any combination of light sources. Computer graphics design and display lumen output are major factors influencing the amount of spectrally intense light projected into the environment and in the viewer's direction. Use of adjustable white point display software was useful only if the predominant background color was white and if it matched the ambient light system's color. Display graphics that used a predominantly black background had the least influence on unplanned spectral energy projected into the environment. Percent reflectance makes a difference in total energy reflected back into an environment, and within certain architectural geometries, reflectance can be used to control the amount of a light spectrum that is allowed to perpetuate in the environment. Data showed that room volume and distance from significant light sources influence the total spectrum in a room. Smaller environments had a homogenizing effect on total light spectrum, whereas light from multiple sources in larger environments was less mixed. The findings indicated above should be considered when making recommendations for practice or standards for architectural systems. The ambient lighting system, surface reflectance, and display and indicator implementation all factor into the users' spectral environment. A variety of low-cost solutions exist to mitigate the impact of light from non-architectural lighting systems, and much potential for system automation and integration of display systems with the ambient environment. This team believes that proper planning can be used to avoid integration problems and also believes that human-in-the-loop evaluations, real-world test and measurement, and computer modeling can be used to determine how changes to a process, display graphics, and architecture will help maintain the planned spectral operating lighting environment.

Clark, T. A.↗
NASA NTRSDate not supplied

Use of Diffusion Bonded Cu Strap and Integrated MLI for Thermal Control of 100 K IR Detector on L’Ralph Instrument

Passive cooling of cryogenic instruments is one of the most challenging aspects of spaceflight thermal control systems. They are highly sensitive to parasitic heat leaks from their warmer environment, especially the spacecraft components. The L’Ralph instrument on the Lucy mission is an example of such a system, with its LEISA detector requiring passive cooling to temperatures below 112 K. MLI performance can be measured in terms of estar, and analysts apply bias between a high and low estar value. This approach works well for conventional MLI at room temperature, however, it can be dangerous when a mission goes through a wide range of temperatures during its lifetime, with estar values increasing exponentially as temperatures get colder. Various estar correlations are presented as well as how L’Ralph is approaching the MLI problem with the use of IMLI. IMLI uses discrete spacers to isolate each layer, and doesn’t require intermediate layers such as dacron netting. This results in estar performance that can be more precisely estimated, and yields valuesaround 0.004 at the 112K operating temperature. L’Ralph is using IMLI on the backside of the radiator, which permits a more effective use of increased radiator area, by minimizing the area dependent heat leak impact from the instrument backloading. The detector is thermally coupled to the radiator via a diffusion bonded Cu strap. The diffusion bonding process chemically bonds the Cu foil ends in order to maximize heat transfer effectiveness across the multiple foils used. Employing a pressure compensation design via the use of Ti blocks and a clamp at the strap ends ensures that as temperatures go colder, pre-load is maintained in order to minimize resistance at the strap ends. The use of both of these technologies, and how they work together are crucial to the success of the L’Ralph thermal control system.

Thermal↗
DOE OSTI2015

Decommissioning of the NPP A-1 heavy water management system - 15121

The paper deals with experience and techniques in the application of decontamination technology and remotely controlled robotic devices for the decontamination and dismantling of the heavy water management system during undergoing decommissioning process of the A-1 NPP as well as treatment of arising liquid waste All of these activities are characterized by high level of radioactivity and contamination. During operation of the A-1 NPP the heavy water management system fulfilled several functions: (1) cooling of the moderator, (2) topping up of the moderator in the active zone, (3) drainage, feed and storage of heavy water, (4) capture of leaked heavy water. Closely associated with heavy water management were systems for separation and isotopic purification of heavy water (distilling station, removing organic impurities station, isotopic purification station). The NPP heavy water system is located inside the power block building in several rooms where the inner surface contamination is up to the level of 10 E4 Bq.cm{sup -2}, dose rate up to 15,0 mGy.h{sup -1} and the feeding pipeline contained liquid RAW with high tritium content. Pre-dismantling decontamination of the heavy water management system and associated systems had to be performed with the intention of improving the radiation situation, i.e. reducing contamination of internal surface and dose rates in the vicinity of the equipment. Various sophisticated procedures such as retrieval of sludge using remotely operated devices and loop chemical decontamination of internal surfaces were applied. The generated radioactive waste such as spent decontamination solutions and sludge were immediately solidified on-site into a geo-polymer matrix using a mobile conditioning facility. For dismantling and fragmentation of some devices, mobile robotic systems MT80 and MT15 were applied which had been developed, designed and constructed as general-purpose decommissioning equipment. Special tooling was developed for application with the robots, such as hydraulic shears, circular saw, reciprocating saw, circular pipe cutter and a system for quick tool-change without direct intervention of the operators. Most of the operations are remotely controlled on basis of visual information from four cameras, with consistent radiation protection of the operators. The implementation of partial decommissioning tasks in such hard and unfavorable radiation conditions (moreover accompanied by generation of specific high-content alpha radwaste) has introduced in practice several new unique decontamination and dismantling techniques and new procedures for the effective on-site processing of generated secondary radioactive waste, including sludge and sorbents. These advantageous techniques, equipment and experience will be exploited in the continuation of the A-1 NPP decommissioning process which has been organized according to distinctively licensed phases and are also being applied in the decommissioning of other NPP in Slovakia as well as abroad. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Both electric field and temperature independent behavior of piezoelectric property of Pb(Ni 1/3 Nb 2/3 )O 3 –PbTiO 3

The temperature stability of electromechanical properties is an important issue of major concern for the design of actuators. In this paper, temperature dependence of ferroelectric properties have been investigated in the (1 - x)Pb(Ni 1/3 Nb 2/3 )O 3– xPbTiO 3 (x = 0.30–0.38) solid solutions. Interestingly, the unipolar strain in the composition of x = 0.38 shows a good linear relationship with increasing electric field, and the large-signal d 33 is independent with increasing temperature from room temperature to 100 °C. Furthermore, it also exhibits a very high piezoelectric coefficient d 33 = 450 pC/N near the morphotropic phase boundary. All above indicates the present system of (1 - x)Pb(Ni 1/3 Nb 2/3 )O 3– xPbTiO 3 may be a kind of potential application for precisely controlling actuators.

36 MATERIALS SCIENCE↗
NASA NTRS2002

Cryogenic Electronics Being Developed for Space Operation

Planetary exploration missions and deep space probes require electrical power management and control systems that can operate efficiently and reliably in very low temperature environments. Presently, spacecraft operating in the cold environment of deep space carry a large number of radioisotope heating units to maintain the surrounding temperature of the onboard electronics at approximately 20 C. Electronics capable of operation at cryogenic temperatures would not only tolerate the hostile environment of deep space but also reduce system size and weight by eliminating or reducing the radioisotope heating units and their associate structures. Thereby, such electronics would reduce system development as well as launch costs. In addition, power electronic circuits designed for operation at low temperatures are expected to result in more efficient systems than those at room temperature. This improvement results because semiconductor and dielectric materials have better behavior and tolerance in their electrical and thermal properties at low temperatures. The Low Temperature Electronics Program at the NASA Glenn Research Center is focusing on the research and development of electrical components, circuits, and systems suitable for applications in the aerospace environment and in deep space exploration missions. Research is being conducted on devices and systems for reliable use down to cryogenic temperatures. Some of the commercial off-the-shelf as well as developed components that are being characterized include semiconductor switching devices, resistors, magnetics, and capacitors. Semiconductor devices and integrated circuits including digital-to-analog and analog-to-digital converters, dc-dc converters, operational amplifiers, and oscillators are also being investigated for potential use in low-temperature applications. For example, the output response of an advanced oscillator at room temperature and at -190 C is shown. Most oscillators can operate at temperatures down to only -55 C. It can be seen that, for this oscillator, the low temperature of -196 C changed the leading and trailing edges of the oscillator pulses by producing overshoot. The research and development efforts performed under the Low Temperature Electronics Program at Glenn are being carried out through collaboration with other Government agencies, industrial and aerospace companies, and academia. The program supports missions as well as technology development efforts at NASA's Goddard Space Flight Center and Langley Research Center, and the Jet Propulsion Laboratory.

Patterson, Richard L.↗
DOE OSTI2021

Trends in best-in-class energy-efficient technologies for room air conditioners

Improving the efficiency of room air conditioners (RACs) could provide significant energy and associated emissions savings, particularly in emerging economies with hot climates where the cooling demand is expected to increase dramatically. To help accelerate efficiency improvements, this study identifies “best-in-class” high-efficiency RAC components and products. The findings show that manufacturers tend to minimize manufacturing costs by using RAC designs that are readily available or standardized to their production, and they share components across various models. High-efficiency RAC models use advanced compressor technologies optimized at a low frequency, large heat exchangers with thermodynamically effective materials and designs, highly efficient direct current fan motors, advanced metering devices, and smart sensors for temperature and humidity control. Recently RAC manufacturers have been improving seasonal efficiency – better reflecting part-load operation – especially via variable-speed (inverter) drives for compressor motors. Recent highest-efficiency RAC models use low global warming potential (GWP) refrigerants, having transitioned from conventional high-GWP refrigerants, in regions where RACs that use these low-GWP refrigerants are commercially available. Recently demonstrated innovative technologies show trends toward smart hybrid designs, evaporative cooling, and solid-state materials beyond the conventional vapor-compression technology. This information could help policymakers improve their RAC market-transformation programs to align with the most-efficient global technology.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1981

Thin film strain transducer

Previous attempts to develop an appropriate sensor for measuring the stress or strain of high altitude balloons during flight are reviewed as well as the various conditions that must be met by such a device. The design, development and calibration of a transducer which promises to satisfy the necessary design constraints are described. The thin film strain transducer has a low effective modulus so as not to interfere with the strain that would naturally occur in the balloon. In addition, the transducer has a high sensitivity to longitudinal strain (7.216 mV/V/unit strain) which is constant for all temperature from room temperature to -80 C and all strains from 5 percent compression to 10 percent tensile strain. At the same time, the sensor is relatively insensitive (0.27 percent) to transverse forces. The device has a standard 350 ohm impedance which is compatible with available bridge balance, amplification and telemetry instrumentation now available for balloon flight. Recommendations are included for improved coatings to provide passive thermal control as well as model, tethered and full scale flight testing.

Rand, J. L.↗
DOE OSTI2014

Reversible piezomagnetoelectric switching in bulk polycrystalline ceramics

Magnetoelectric (ME) coupling in materials offer tremendous advantages in device functionality enabling technologies including advanced electronic memory, combining electronic speed, and efficiency with magnetic robustness. However, low cost polycrystalline ME materials are excluded from most commercial applications, operating only at cryogenic temperatures, impractically large electric/magnetic fields, or with low ME coefficients (1-100 mV/cm Oe). Despite this, the technological potential of single compound ME coupling has continued to drive research into multiferroics over the last two decades. Here we show that by manipulating the large induced atomic strain within the polycrystalline, room temperature multiferroic compound 0.7BiFeO{sub 3}–0.3PbTiO{sub 3}, we can induce a reversible, piezoelectric strain controlled ME effect. Employing an in situ neutron diffraction experiment, we have demonstrated that this piezomagnetoelectric effect manifests with an applied electric field >8 kV/mm at the onset of piezoelectric strain, engineered in to the compound by crystallographic phase mixing. This produces a remarkable intrinsic ME coefficient of 1276 mV/cm Oe, due to a strain driven modification to the oxygen sub-lattice, inducing an increase in magnetic moment per Fe{sup 3+} ion of +0.142 μ{sub B}. This work provides a framework for investigations into strain engineered nanostructures to realize low-cost ME devices designed from the atoms up, as well as contributing to the deeper understanding of single phase ME coupling mechanisms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Transport Mediating Core–Shell Photocatalyst Architecture for Selective Alkane Oxidation

The high activation barrier of the C-H bond in methane, combined with the high propensity of methanol and other liquid oxygenates toward overoxidation to CO 2 , have historically posed significant scientific and industrial challenges to the selective and direct conversion of methane to energy-dense fuels and chemical feedstocks. Here, we report a unique core-shell nanostructured photocatalyst, silica encapsulated TiO 2 decorated with AuPd nanoparticles (TiO 2 @SiO 2 -AuPd), that prevents methanol overoxidation on its surface and possesses high selectivity and yield of oxygenates even at high UV intensity. This room-temperature approach achieves high selectivity for oxygenates (94.5%) with a total oxygenate yield of 15.4 mmol/g cat ·h at 9.65 bar total pressure of CH 4 and O 2 . The working principles of this core-shell photocatalyst were also systematically investigated. Finally, this design concept was further demonstrated to be generalizable for the selective oxidation of other alkanes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1988

A signal filter with zero phase lag

Rotorcraft and rotorcraft models are tested at the NASA Ames National Full-Scale Aerodynamics Complex (NFAC). The models tested in the NFAC wind tunnels are controlled by a remote control console located in a control room. Certain critical information must be displayed on the control console to monitor the rotor to insure that the rotor is within operational limits. The signal for these parameters is complex (with ac and dc components) and is derived from pitch and flapping transducers on the rotor head. The pitch and flapping cyclics are derived from resolver circuits that indicate the magnitude and phase of the cyclics. Conventional filter circuits used to separate the ac and dc components have a phase lag on the ac component, which will introduce an error in the cyclic vector. To overcome this error, a filter with zero phase lag needed to be developed. This paper discusses a rotorcraft circuit that was designed to have an ac/dc filter with zero phase lag over the frequency range.

Forsyth, T. J.↗
NASA NTRS1997

Identification of Error Patterns in Terminal-Area ATC Communications

Advancing air traffic management technologies have enabled a greater number of aircraft to use the same airspace more effectively. As aircraft separations are reduced and final approaches are more finely timed, there is less room for error. The present study examined 122 terminal-area, loss-of-separation and procedure violation incidents reported to the Aviation Safety Reporting System (ASRS) by air traffic controllers. Narrative description codes were used for the incidents for type of violation, contributing factors, recovery strategies, and consequences. Usually multiple errors occurred prior to the violation. Error sequences were analyzed and common patterns of errors were identified. In half of the incidents, errors were noticed in time to correct mistakes. Of these, almost 43% committed additional errors during the recovery attempt. This analysis shows that redundancies in the present air traffic control system may not be sufficient to support large increases in traffic density. Error prevention and design considerations for air traffic management systems are discussed.

Quinn, Cheryl↗
NASA NTRS2003

Electronic Components and Circuits for Extreme Temperature Environments

Planetary exploration missions and deep space probes require electrical power management and control systems that are capable of efficient and reliable operation in very low temperature environments. Presently, spacecraft operating in the cold environment of deep space carry a large number of radioisotope heating units in order to maintain the surrounding temperature of the on-board electronics at approximately 20 C. Electronics capable of operation at cryogenic temperatures will not only tolerate the hostile environment of deep space but also reduce system size and weight by eliminating or reducing the radioisotope heating units and their associate structures; thereby reducing system development as well as launch costs. In addition, power electronic circuits designed for operation at low temperatures are expected to result in more efficient systems than those at room temperature. This improvement results from better behavior and tolerance in the electrical and thermal properties of semiconductor and dielectric materials at low temperatures. The Low Temperature Electronics Program at the NASA Glenn Research Center focuses on research and development of electrical components, circuits, and systems suitable for applications in the aerospace environment and deep space exploration missions. Research is being conducted on devices and systems for reliable use down to cryogenic temperatures. Some of the commercial-off-the-shelf as well as developed components that are being characterized include switching devices, resistors, magnetics, and capacitors. Semiconductor devices and integrated circuits including digital-to-analog and analog-to-digital converters, DC/DC converters, operational amplifiers, and oscillators are also being investigated for potential use in low temperature applications. An overview of the NASA Glenn Research Center Low Temperature Electronic Program will be presented in this paper. A description of the low temperature test facilities along with selected data obtained through in-house component and circuit testing will also be discussed. Ongoing research activities that are being performed in collaboration with various organizations will also be presented.

Patterson, Richard L.↗
DOE OSTI2012

Long-Term Results from Evaluation of Advanced New Construction Packages in Test Homes. Martha's Vineyard, Massachusetts

This report presents a cold climate project located in West Tisbury, Massachusetts, on the island of Martha’s Vineyard, that examines the relationships among very energy efficient single-family residential thermal enclosures, room-to-room temperature variations, and simplified space conditioning systems. Each of the four homes studied has a single ductless heat pump unit (DHU) located in the main living space and radiant electric resistance panels in each bedroom with individual thermostatic controls. Results indicate that temperature fluctuations in the living room due to aggressive setup and setback of the DHU may contribute to higher percentages of time where the bedroom temperatures were within +/-2°F of the living room temperatures. Solar gains in the living room, door opening/closure and occupant manipulation of thermostats appear to have had a significant impact on room-to-room temperature differences, as would be expected.

building energy optimization↗