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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Vacuum-Assisted Low-Temperature Synthesis of Reduced Graphene Oxide Thin-Film Electrodes for High-Performance Transparent and Flexible All-Solid-State Supercapacitors

Simple and easily integrated design of flexible and transparent electrode materials affixed to polymer-based substrates hold great promise to have a revolutionary impact on the functionality and performance of energy storage devices for many future consumer electronics. Among these applications are touch sensors, roll-up displays, photovoltaic cells, health monitors, wireless sensors, and wearable communication devices. Here, we report an environmentally friendly, simple, and versatile approach to produce optically transparent and mechanically flexible all-solid-state supercapacitor devices. These supercapacitors were constructed on tin-doped indium oxide coated polyethylene terephthalate substrates by intercalation of a polymer-based gel electrolyte between two reduced graphene oxide (rGO) thin-film electrodes. The rGO electrodes were fabricated simply by drop-casting of graphene oxide (GO) films, followed by a novel low-temperature (≤250 °C) vacuum-assisted annealing approach for the in situ reduction of GO to rGO. A trade-off between the optical transparency and electrochemical performance is determined by the concentration of the GO in the initial dispersion, whereby the highest capacitance (~650 μF cm –2 ) occurs at a relatively lower optical transmittance (24%). Notably, the all-solid-state supercapacitors demonstrated excellent mechanical flexibility with a capacity retention rate above 90% under various bending angles and cycles. In conclusion, these attributes underscore the potential of the present approach to provide a path toward the realization of thin-film-based supercapacitors as flexible and transparent energy storage devices for a variety of practical applications.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Comparative toxicity assessment of novel Si quantum dots and their traditional Cd-based counterparts using bacteria models Shewanella oneidensis and Bacillus subtilis

Quantum dots are crystalline semiconductor nanoparticles with unique optical properties due to quantum confinement effects. They have several advantages compared to traditional organic fluorescent dyes, such as high fluorescent brightness, photostability, and tunable emission wavelengths, dependent upon particle size. Their unique optical properties have led to an increased use in a variety of devices, including diode lasers and television displays, as well as in biomedical research. The most commonly used quantum dots (QDs) are made of cadmium selenide (CdSe) and have cadmium selenide core with zinc sulfide shell (CdSe/ZnS), containing inherently toxic cadmium. This work focuses on comparison of the toxic effects of conventional CdSe and CdSe/ZnS QDs and silicon QDs, which are emerging as a potentially benign alternative, using bacteria as model organisms. The bacteria models used for our studies are Shewanella oneidensis MR-1, a Gram-negative bacterium, and Bacillus subtilis SB 491, a Gram-positive bacterium. Furthermore, this research assesses changes in cell viability, respiration pattern, and cell membrane integrity in the presence of the nanoparticles using colony counting, respirometry and membrane integrity assays, respectively. The association of the QDs with bacterial cell membranes was investigated using transmission electron microscopy (TEM). Results indicate that the silicon QDs are benign to the bacteria considered, and they do not associate with the cell membranes. The CdSe cores exhibit significant toxicity to the bacterial cells, whereas the CdSe/ZnS QDs are comparatively less toxic.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Engineering the anchoring behavior of nematic liquid crystals on a solid surface by varying the density of liquid crystalline polymer brushes

Controlling the orientation of liquid crystal (LC) molecules towards contacting surfaces is a crucial requirement for the development of LC displays and passive electro-optical devices. Up to now, research has been focused on photo-responses of a LC azobenzene polymer system to obtain either planar or homeotropic orientation of LCs. It remains a challenge, however, to tune the polar angle of LC molecules on the solid surface and gain more insights about the polymer chain conformation extending in LC medium. Here, we deposit a liquid crystalline side chain polymer brush, poly(6-(4-methoxy-azobenzene-4'-oxy)hexyl methacrylate) (PMMAZO), onto the solid surface with film thickness varying between ~3 nm and 13 nm; therefore, the grafting density of the brush layer ranges from 0.0219 to 0.0924 chains per nm 2 . When LCs are confined in hybrid cells with a top surface eliciting uniform homeotropic anchoring and a bottom surface covered by the PMMAZO brush, the out-of-plane polar angle of 4-pentyl-4'-cyanobiphenyl (5CB) on the brush layer gradually changes from ~0° to ~62° by simply increasing the grafting brush density. The surface forces apparatus (SFA) measurement is used to determine 5CB as a good solvent for the PMMAZO brush and understand the relationship between the chain conformation in 5CB and the anchoring behavior of LC molecules on the polymer brush layer. Here, for high grafting density, the polymer chain in 5CB extends significantly away from the substrate, making the side chain mesogens on average almost parallel to the substrate; for the low-density case, the main chain extends in the narrow region around the surface for aligning the mesogens perpendicular to the substrate.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Multi-resonator structure based on continuous silver thin films for transparent conductors

A type of metal-dielectric multilayered structures is investigated theoretically and experimentally for achieving optical transparency with a high electrical conductivity. The structure in our demonstrated case comprises of two coupled metal-dielectric-metal planar optical resonators with metal-layer thicknesses near to its skin depth. Simulations show that the maximum transmittance for visible light can easily reach 90% for silver-based structures. Experimentally, the sample fabricated exhibits a transmission window with a bandwidth of 150 nm and a maximum transmittance of 76% around 643 nm wavelength at normal incidence. Its sheet resistance is measured to be less than 10Ω/□, much smaller than that of common indium-tin-oxide films. Transparent conductors functioning for blue light and even for the whole visible light are also shown to be theoretically possible. Owing to their simple fabrication procedure as well as design flexibility, such a layered structure can serve as a compelling alternative as transparent conductors for optoelectronic devices, especially for liquid-crystal displays and light-emitting diodes.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Versatile alignment layer method for new types of liquid crystal photonic devices

Liquid crystal photonic devices are becoming increasingly popular. These devices often present a challenge when it comes to creating a robust alignment layer in pre-assembled cells. In this paper, we describe a method of infusing a dye into a microcavity to produce an effective photo-definable alignment layer. However, previous research on such alignment layers has shown that they have limited stability, particularly against subsequent light exposure. As such, we further describe a method of utilizing a pre-polymer, infused into the microcavity along with the liquid crystal, to provide photostability. We demonstrate that the polymer layer, formed under ultraviolet irradiation of liquid crystal cells, has been effectively localized to a thin region near the substrate surface and provides a significant improvement in the photostability of the liquid crystal alignment. This versatile alignment layer method, capable of being utilized in devices from the described microcavities to displays, offers significant promise for new photonics applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

EPICS for small-scale laboratories with Python soft IOCs

While the Experimental Physics and Industrial Control System (EPICS) is widely used at large laboratories for slow controls and instrumentation, the deployment of a full EPICS installation can be difficult, with a steep learning curve to new users. Taking advantage of the pythonSoftIOC module, we developed an EPICS slow controls implementation for Jefferson Lab's Hall B cryotarget written entirely in Python and based on software IOCs that communicate with instruments over Ethernet. Here, this system ran successfully, interfacing with Jefferson Lab's full EPICS network, and we offer it as an example of the capabilities of pythonSoftIOC to build lightweight, yet robust and flexible instrumentation platforms that would be easily adapted for use at a small-scale laboratory. University groups can use these examples to build complete slow controls systems, from device communication to data archiving and display, using open-source, mature EPICS tools and student-friendly Python as an alternative to expensive and proprietary systems such as LabVIEW.

Computing↗
DOE OSTI2019

Spin-orbit coupling induced robust spin-Seebeck effect and pure thermal spin currents in achiral molecule systems

Spin-Seebeck effect (SSE) is an effective route to realize pure spin current by using spin-polarized electrons or spin-wave transport in magnetic systems. In this work we propose a route, i.e., by using spin-orbit coupling (SOC), to achieve robust SSE characterized by pure thermal spin current. The material examples are constructed on achiral nanotubes, and the theoretical results reveal that (i) as temperature gradient is applied along the nanotubes, thermal spin-up and spin-down currents with opposite flow directions are produced without any accompanying charge current, (ii) the SSE is robust against decoherence and nonuniform interchain SOC, (iii) the thermal spin currents display a multioscillation feature with increasing device temperatures, supporting their potential device applications in thermal spin-current multiswitcher, and (vi) strain engineering in the radical direction of nanotubes is an effective way to improve SSE and to control pure thermal spin current. These inspiring spin transport behaviors in achiral molecular systems put forward a mechanism to realize the robust SSE characterized by pure spin current and develop the research field of spin-orbito-caloritronics, which focuses on the interplay of electrons’ spin and orbital degrees of freedom in the presence of temperature gradient.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

A High-Speed Large-Range Tip-Tilt-Piston Micromirror Array

This work introduces the design of a high fill-factor (>99%) micromirror array (MMA) that consists of 1mm2 hexagonal mirrors, which are expected to each independently achieve continuous, closed-loop control of three degrees of freedom (DOFs)—tip, tilt, and piston—over large ranges (>±10o rotation and >±30μm translation) at high speeds (~45kHz for a 1o amplitude of rotational oscillation). The flexure topology of this array is designed using the Freedom, Actuation, and Constraint Topologies (FACT) synthesis approach, which utilizes geometric shapes to help designers rapidly consider every flexure topology that best achieves a desired set of DOFs driven by decoupled actuators. The geometry of this array’s comb-drive actuators are optimized in conjunction with the geometry of the system’s flexures using a novel approach. The analytical models underlying this approach are verified using finite element analysis (FEA) and validated using experimental data. The capabilities of this new mirror array will enable, or significantly improve, the performance of a variety of high-impact optical technologies such as advanced optical switches, spatial-light modulators, displays, and laser steering or scanning devices.

42 ENGINEERING↗
DOE OSTI2021

Efficient light-emitting diodes based on oriented perovskite nanoplatelets

Solution-processed planar perovskite light-emitting diodes (LEDs) promise high-performance and cost-effective electroluminescent devices ideal for large-area display and lighting applications. Exploiting emission layers with high ratios of horizontal transition dipole moments (TDMs) is expected to boost the photon outcoupling of planar LEDs. However, LEDs based on anisotropic perovskite nanoemitters remain to be inefficient (external quantum efficiency, EQE <5%) due to the difficulties of simultaneously controlling the orientations of TDMs, achieving high photoluminescence quantum yields (PLQYs) and realizing charge balance in the films of assembled nanostructures. Here, we demonstrate efficient electroluminescence from an in situ grown perovskite film composed of a monolayer of face-on oriented nanoplatelets. The ratio of horizontal TDMs of the perovskite nanoplatelet film is ~84%, which leads to a light-outcoupling efficiency of ~31%, substantially higher than that of isotropic emitters (~23%). In consequence, LEDs with a peak EQE of 23.6% are achieved, representing highly efficient planar perovskite LEDs.

36 MATERIALS SCIENCE↗
NASA NTRS1975

Multipurpose panel, phase 1, study report

The feasibility of a multipurpose panel which provides a programmable electronic display for changeable panel nomenclature, multiplexes similar indicator display signals to the signal display, and demultiplexes command signals is examined. Topics discussed include: electronic display technology, miniaturized electronic and memory devices, and data management systems which employ digital address and multiplexing.

Parkin, W.↗
NASA NTRS1978

Making aerospace technology work for the automotive industry - Introduction

In many cases it has been found that advances made in one technical field can contribute to other fields. An investigation is in this connection conducted concerning subjects from contemporary NASA programs and projects which might have relevance and potential usefulness to the automotive industry. Examples regarding aerospace developments which have been utilized by the automotive industry are related to electronic design, computer systems, quality control experience, a NASA combustion scanner and television display, exhaust gas analyzers, and a device for suppressing noise propagated through ducts. Projects undertaken by NASA's center for propulsion and power research are examined with respect to their value for the automotive industry. As a result of some of these projects, a gas turbine engine and a Stirling engine might each become a possible alternative to the conventional spark ignition engine.

Olson, W. T.↗
NASA NTRS1979

Medical diagnosis system and method with multispectral imaging

A skin diagnosis system includes a scanning and optical arrangement whereby light reflected from each incremental area (pixel) of the skin is directed simultaneously to three separate light filters, e.g., IR, red, and green. As a result, the three devices simultaneously produce three signals which are directly related to the reflectance of light of different wavelengths from the corresponding pixel. These three signals for each pixel after processing are used as inputs to one or more output devices to produce a visual color display and/or a hard copy color print, for one usable as a diagnostic aid by a physician.

Anselmo, V. J.↗
NASA NTRS1984

Manned maneuvering unit simulations on the Space Operations Simulator

Details of the Manned Maneuvering Unit (MMU) and its use is discussed. MMU simulations in the Space Operations Simulator (SOS) use two major devices. The first is a six-degree-of-freedom moving base carriage that allows the trainee freedom to fly the MMU in a large room and to match rates and dock with full scale targets. The second device is a large screen television display that provides the trainee with accurate views of tumbling targets from any point in a surrounding sphere up to 300 meters (1000 feet) in diameter. Astronauts used the SOS to train for the Solar Max repair mission and are now using it to train for a mission to recover the Palapa-B communications satellite. Subjective comparisons by astronauts of an orbit MMU performance to simulated MMU performance in the SOS indicate that the simulations are very realistic. Data from the Solar Max mission have resulted in two software upgrades that increase SOS fidelity for the next MMU mission: a model of contact dynamics between the MMU and a target spacecraft, and a model of MMU plume impingement forces during docking.

Hartley, C.↗
NASA NTRS1982

Distribution of man-machine controls in space teleoperation

The distribution of control between man and machine is dependent on the tasks, available technology, human performance characteristics and control goals. This dependency has very specific projections on systems designed for teleoperation in space. This paper gives a brief outline of the space-related issues and presents the results of advanced teleoperator research and development at the Jet Propulsion Laboratory (JPL). The research and development work includes smart sensors, flexible computer controls and intelligent man-machine interface devices in the area of visual displays and kinesthetic man-machine coupling in remote control of manipulators. Some of the development results have been tested at the Johnson Space Center (JSC) using the simulated full-scale Shuttle Remote Manipulator System (RMS). The research and development work for advanced space teleoperation is far from complete and poses many interdisciplinary challenges.

Bejczy, A. K.↗
NASA NTRS1985

Flowmeter for Clear and Translucent Fluids

Transducer with only three moving parts senses flow of clear or translucent fluid. Displacement of diaphragm by force of flow detected electrooptically and displayed by panel meter or other device. Transducer used to measure flow of gasoline to automobile engine.

White, P. R.↗
NASA NTRS1986

Low-Resistivity Zinc Selenide for Heterojunctions

Magnetron reactive sputtering enables doping of this semiconductor. Proposed method of reactive sputtering combined with doping shows potential for yielding low-resistivity zinc selenide films. Zinc selenide attractive material for forming heterojunctions with other semiconductor compounds as zinc phosphide, cadmium telluride, and gallium arsenide. Semiconductor junctions promising for future optoelectronic devices, including solar cells and electroluminescent displays. Resistivities of zinc selenide layers deposited by evaporation or chemical vapor deposition too high to form practical heterojunctions.

Stirn, R. J.↗