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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 145 records · Page 8

Thermally Stable Co@C3N4 Single-Atom Catalysts for CO Oxidation: Atomic-Level Insights into Structure and Activity

Single Co atoms supported on C3N4 (Co@C3N4) have demonstrated high activity and selectivity in photocatalysis. However, the investigation of structure–function relationships and reaction mechanisms under photocatalytic conditions is very challenging due to the complex conditions of light absorption, charge transfer, and catalysis. In this study, we employed thermal CO oxidation as a prototypical probe reaction to benchmark the intrinsic catalytic performance and track the active-site evolution of Co@C3N4. Single Co atoms were identified and shown to be the catalytically active sites for CO oxidation based on control experiments and isotope-labeling experiments. The Co sites remained atomically dispersed before, during, and after the reaction with temperatures up to 400 °C, as established by in situ X-ray absorption fine structure (XAFS) combined with density functional theory (DFT), FDMNES simulations, and dynamic-time-warping (DTW)-assisted X-ray absorption near edge structure (XANES) matching. Together with theoretical calculations, the integrated analysis reveals a stable coordination environment under reaction conditions, which correlates with sustained activity, establishing Co@C3N4 single-atom catalysts as thermally stable CO oxidation catalysts. Beyond these findings, the current study provides a workflow for unambiguously assigning active sites in Co@C3N4 for thermal CO oxidation. This workflow will aid the understanding of their behavior in photocatalysis in the future, where light-driven dynamics obscure direct structure–function links. Notably, this study provides fundamental insights for the rational design of robust single-atom catalysts and a foundation for the broader application of Co@C3N4 catalysts in oxidation reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Graphical programming: A systems approach for telerobotic servicing of space assets

Satellite servicing is in many ways analogous to subsea robotic servicing in the late 1970's. A cost effective, reliable, telerobotic capability had to be demonstrated before the oil companies invested money in deep water robot serviceable production facilities. In the same sense, aeronautic engineers will not design satellites for telerobotic servicing until such a quantifiable capability has been demonstrated. New space servicing systems will be markedly different than existing space robot systems. Past space manipulator systems, including the Space Shuttle's robot arm, have used master/slave technologies with poor fidelity, slow operating speeds and most importantly, in-orbit human operators. In contrast, new systems will be capable of precision operations, conducted at higher rates of speed, and be commanded via ground-control communication links. Challenge presented by this environment include achieving a mandated level of robustness and dependability, radiation hardening, minimum weight and power consumption, and a system which accommodates the inherent communication delay between the ground station and the satellite. There is also a need for a user interface which is easy to use, ensures collision free motions, and is capable of adjusting to an unknown workcell (for repair operations the condition of the satellite may not be known in advance). This paper describes the novel technologies required to deliver such a capability.

Pinkerton, James T.↗

Shuttle Payload Ground Command and Control: An Experiment Implementation Combustion Module-2 Software Development, STS-107

This presentation covers the design of a command and control architecture developed by the author for the Combustion Module-2 microgravity experiment, which flew aboard the STS-107 Shuttle mission, The design was implemented to satisfy a hybrid network that utilized TCP/IP for both the onboard segment and ground segment, with an intermediary unreliable transport for the space to ground segment. With the infusion of Internet networking technologies into Space Shuttle, Space Station, and spacecraft avionics systems, comes the need for robust methodologies for ground command and control. Considerations of high bit error links, and unreliable transport over intermittent links must be considered in such systems. Internet protocols applied to these systems, coupled with the appropriate application layer protections, can provide adequate communication architectures for command and control. However, there are inherent limitations and additional complexities added by the use of Internet protocols that must be considered during the design. This presentation will discuss the rationale for the: framework and protocol algorithms developed by the author. A summary of design considerations, implantation issues, and learned lessons will be will be presented. A summary of mission results using this communications architecture will be presented. Additionally, areas of further needed investigation will be identified.

Carek, David Andrew↗

Background and architecture for an autonomous ground station controller

The Deep Space Station Controller (DSSC) is state of the art ground station control architecture being developed at JPL. During the past few years the technology development program at JPL demonstrated a series of increasingly competent automated ground station prototypes of which the DSSC is the latest. It has been designed for robust closed loop control of ground stations utilized for forward and return link communications with NASA's deep space exploration missions.

controller for ground station automation fault det↗

Spacesuit Evaporator-Absorber-Radiator (SEAR)

For decades advanced spacesuit developers have pursued a regenerable, robust nonventing system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s Lithium Chloride Absorber Radiator (LCAR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. This water vapor is then captured by solid LiCl in the LCAR with a high enthalpy of absorption, resulting in sufficient temperature lift to reject heat to space by radiation. After the sortie, the LCAR would be heated up and dried in a regenerator to drive off and recover the absorbed evaporant. A engineering development prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The LCAR was able to stably reject 75 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

Hodgson, Ed↗

Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

Satellite Communications↗

Comparison of chamber beam geometry robustness to mispointing, imbalance and target offset for direct-drive laser fusion facilities

This study focuses on the optimization of beam chamber geometry designs for future direct-drive laser facilities. It provides a review of leading target chamber geometries, with a particular emphasis on random errors. Through comprehensive solid-sphere illuminations and analysis, we identify an optimized beam geometry design, highlighting its robustness and performance under realistic experimental conditions. Three major sources of random errors are evaluated, closely linked to experimental evaluations at OMEGA. The findings underscore the importance of optimizing the irradiation system alongside beam pattern considerations to enhance the efficiency and reliability of inertial confinement fusion experiments. We conclude that for a desired illumination uniformity of 1% in the presence of system errors, the split icosahedron design is the most robust. However, for a 0.3% uniformity goal, the charged-particle, icosahedron, and t-sphere methods exhibit similar performance.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA Tech Briefs, October 2010

Topics covered include: Hybrid Architecture Active Wavefront Sensing and Control; Carbon-Nanotube-Based Chemical Gas Sensor; Aerogel-Positronium Technology for the Detection of Small Quantities of Organic and/or Toxic Materials; Graphene-Based Reversible Nano-Switch/Sensor Schottky Diode; Inductive Non-Contact Position Sensor; High-Temperature Surface-Acoustic-Wave Transducer; Grid-Sphere Electrodes for Contact with Ionospheric Plasma; Enabling IP Header Compression in COTS Routers via Frame Relay on a Simplex Link; Ka-Band SiGe Receiver Front-End MMIC for Transponder Applications; Robust Optimization Design Algorithm for High-Frequency TWTs; Optimal and Local Connectivity Between Neuron and Synapse Array in the Quantum Dot/Silicon Brain; Method and Circuit for In-Situ Health Monitoring of Solar Cells in Space; BGen: A UML Behavior Network Generator Tool; Platform for Post-Processing Waveform-Based NDE; Electrochemical Hydrogen Peroxide Generator; Fabrication of Single, Vertically Aligned Carbon Nanotubes in 3D Nanoscale Architectures; Process to Create High-Fidelity Lunar Dust Simulants; Lithium-Ion Electrolytes Containing Phosphorous-Based, Flame-Retardant Additives; InGaP Heterojunction Barrier Solar Cells; Straight-Pore Microfilter with Efficient Regeneration; Determining Shear Stress Distribution in a Laminate; Self-Adjusting Liquid Injectors for Combustors; Handling Qualities Prediction of an F-16XL-Based Reduced Sonic Boom Aircraft; Tele-Robotic ATHLETE Controller for Kinematics - TRACK; Three-Wheel Brush-Wheel Sampler; Heterodyne Interferometer Angle Metrology; Aligning Astronomical Telescopes via Identification of Stars; Generation of Optical Combs in a WGM Resonator from a Bichromatic Pump; Large-Format AlGaN PIN Photodiode Arrays for UV Images; Fiber-Coupled Planar Light-Wave Circuit for Seed Laser Control in High Spectral Resolution Lidar Systems; On Calculating the Zero-Gravity Surface Figure of a Mirror; Optical Modification of Casimir Forces for Improved Function of Micro- and Nano-Scale Devices; Analysis, Simulation, and Verification of Knowledge-Based, Rule-Based, and Expert Systems; Core and Off-Core Processes in Systems Engineering; Digital Reconstruction Supporting Investigation of Mishaps; and Template Matching Approach to Signal Prediction.

Source record↗

Cross-Cutting Flight Infrastructure Improvements on M2020

Mars2020 (M2020) was formulated as a mission that leveraged as much Mars Science Laboratory (MSL) heritage as possible, while focusing major new development efforts on the original and unique elements needed to accomplish the different mission objectives. Well publicized examples of high profile new developments include precision landing, the sampling and caching system, the specific instrument suite, improved mobility via Autonomous Navigation, and later the addition of the Ingenuity helicopter. Less well known are the refinements to the core flight infrastructure, primarily in the cross-cutting functions of Telecom, Avionics, Data Management, Communications Behaviors, and Parameter Management. These enhancements are introduced predominately via flight software, and represent increases in capability that justified their inclusion in an otherwise heritage-focused project environment.Perseverance’s cross-cutting flight infrastructure improvements fall into and across the following five categories. First is a trimming of the software footprint of infrastructure modules, in order to make room for memory demands elsewhere in the system. Second is the minimization of data volume to be downlinked, through various methods such as the incorporation of new compression options. Third is the maximization of the available downlink bandwidth for data, by curtailing content-less data (fill) and introducing an improved UHF proximity link protocol. Fourth is a reduction in vulnerabilities, through increased file system redundancy, robustness, and software process monitoring. Fifth is an increase in operations efficiency by lowering file system mount times, improving parallelism between simultaneous events, minimizing the time to recover from file system errors, streamlining the purging of obsolete data, and reducing the number of commands to service parameters by a factor of 100.Individually, none of the cross-cutting infrastructure improvements are likely to garner headlines, but collectively they appreciably improve the safety and operability of Perseverance over its predecessor. This paper will describe the improvements, their promise, and where applicable, their actual impact in operations.

Bohannon, Emily↗

Using Mesh Networking for A Dynamic Lunar Internet of Things (Liot)

The purpose of this project is to evaluate the feasibility of an IEEE 802.11 mesh protocol for lunar surface computing. This standard for wireless networking boosts speed, dependability and range of wireless transmissions. The concept is to integrate sensors (such as deployed science instruments) or Astronaut tools (such as a handheld spectrometer) that communicate with a node on a common cell. The nodes can extend the range of the cell and can dynamically reconfigure the data routing in case of another node failure. All of the data in a cell pass through a modem that communicates with a distant base station across a 4G link. The application of mesh networking to a potential lunar surface network increases robustness and fault tolerance over a traditional single-point modem system. By demonstrating the basic capability of a mesh network, the student team has learned about issues with power, distance, thermal, dust, radiation, data processing, and communication problems applicable to the lunar surface. This knowledge can feed into future NASA requirements to improve the capability of a LunaNET implementation for the Artemis program. This project follows 10 years of successful collaboration between NASA ARES, Texas Space, Technology, Applications and Research (T STAR) and Texas A&M University in a Public, Private, Academic (PPA) Partnership. NASA funds T STAR to mentor undergraduate Capstone teams in the College of Engineering Department to design, built, and test prototypes meeting NASA requirements. TAMU faculty lead the student teams in their academic class, and NASA Subject Matter Experts (SMEs) provide T STAR and students insight on requirements evolution, prior design projects, and future development goals.

Lunar Mesh Networking↗

A Photonic Clockwork for Deployed Timing and Radar

We present an environmentally robust photonic RF/microwave clockwork with low size, weight, and power (SWaP) for next-generation, field-deployable timing and radar applications. Compared to microwave references, optical local oscillators offer superior fractional frequency stability and phase-noise performance. When transferred with high fidelity into the RF/microwave domain, this “optical advantage” promises unparalleled performance across both private-industry and government (e.g., defense and space-agency) applications including very-long-baseline interferometry (VLBI), alternative positioning, navigation, and timing (PNT), multi-static synthetic aperture radar (MSAR), and geodetic sensing. However, this potential has yet to be fully realized outside the metrology lab primarily due to the high-SWaP and excessive environmental susceptibility of both the optical reference itself as well as the optical frequency comb (OFC) required to transfer the optical stability into the RF/microwave domain. Here, we present two demonstrations of a low-SWaP, environmentally robust photonic clockwork used to make a high-fidelity optical-microwave link with the stability and phase-noise performance relevant to the applications described above. Additionally, operational-testing results of the OFC subsystem under application-relevant environmental conditions will be presented to show pathway to field deployment of this critical subsystem.

Guangning Yang↗

Hierarchical Modeling and Robust Synthesis for the Preliminary Design of Large Scale Complex Systems

Large-scale complex systems are characterized by multiple interacting subsystems and the analysis of multiple disciplines. The design and development of such systems inevitably requires the resolution of multiple conflicting objectives. The size of complex systems, however, prohibits the development of comprehensive system models, and thus these systems must be partitioned into their constituent parts. Because simultaneous solution of individual subsystem models is often not manageable iteration is inevitable and often excessive. In this dissertation these issues are addressed through the development of a method for hierarchical robust preliminary design exploration to facilitate concurrent system and subsystem design exploration, for the concurrent generation of robust system and subsystem specifications for the preliminary design of multi-level, multi-objective, large-scale complex systems. This method is developed through the integration and expansion of current design techniques: Hierarchical partitioning and modeling techniques for partitioning large-scale complex systems into more tractable parts, and allowing integration of subproblems for system synthesis; Statistical experimentation and approximation techniques for increasing both the efficiency and the comprehensiveness of preliminary design exploration; and Noise modeling techniques for implementing robust preliminary design when approximate models are employed. Hierarchical partitioning and modeling techniques including intermediate responses, linking variables, and compatibility constraints are incorporated within a hierarchical compromise decision support problem formulation for synthesizing subproblem solutions for a partitioned system. Experimentation and approximation techniques are employed for concurrent investigations and modeling of partitioned subproblems. A modified composite experiment is introduced for fitting better predictive models across the ranges of the factors, and an approach for constructing partitioned response surfaces is developed to reduce the computational expense of experimentation for fitting models in a large number of factors. Noise modeling techniques are compared and recommendations are offered for the implementation of robust design when approximate models are sought. These techniques, approaches, and recommendations are incorporated within the method developed for hierarchical robust preliminary design exploration. This method as well as the associated approaches are illustrated through their application to the preliminary design of a commercial turbofan turbine propulsion system. The case study is developed in collaboration with Allison Engine Company, Rolls Royce Aerospace, and is based on the Allison AE3007 existing engine designed for midsize commercial, regional business jets. For this case study, the turbofan system-level problem is partitioned into engine cycle design and configuration design and a compressor modules integrated for more detailed subsystem-level design exploration, improving system evaluation. The fan and low pressure turbine subsystems are also modeled, but in less detail. Given the defined partitioning, these subproblems are investigated independently and concurrently, and response surface models are constructed to approximate the responses of each. These response models are then incorporated within a commercial turbofan hierarchical compromise decision support problem formulation. Five design scenarios are investigated, and robust solutions are identified. The method and solutions identified are verified by comparison with the AE3007 engine. The solutions obtained are similar to the AE3007 cycle and configuration, but are better with respect to many of the requirements.

Koch, Patrick N.↗

Pressure-Induced Superconductivity in the Wide-Band-Gap Semiconductor Cu 2 Br 2 Se 6 with a Robust Framework

We report pressure-induced superconductivity in a ternary and nonmagnetic Cu-containing semiconductor, Cu 2 Br 2 Se 6 , with a wide band gap of 1.89 eV, in which the Cu and Br atoms generate infinite 2, helical chains along the c-axis and are linked by the cyclohexane-like Se 6 rings to form a three-dimensional framework. We find that this framework is remarkably robust under compression, and the ambient-pressure phase survives at least to our experimental limit of 32.1 GPa. Concurrent semiconductor-to-metal transition and superconductivity are observed above 21.0 GPa. The superconducting temperature monotonically increases from 4.0 to 6.7 K at 40.0 GPa. Furthermore, first-principles calculations show that the emergence of superconductivity is associated with the formation of weak multicentered bonds that involve the increase in coordination of the Cu atoms and a subset of the Se atoms. The observation of superconductivity in this type of nonmagnetic transition-metal-based material will inspire the exploration of related new superconductors under pressure.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Optical Phased Array Antennas using Coupled Vertical Cavity Surface Emitting Lasers

High data rate communication links are needed to meet the needs of NASA as well as other organizations to develop space-based optical communication systems. These systems must be robust to high radiation environments, reliable, and operate over a wide temperature range. Highly desirable features include beam steering capability, reconfigurability, low power consumption, and small aperture size. Optical communication links, using coupled vertical cavity surface emitting laser radiating elements are promising candidates for the transmit portion of these communication links. In this talk we describe a mission scenario, and how the antenna requirements are derived from the mission needs. We describe a potential architecture for this type of antenna, and outline the advantages and drawbacks of this approach relative to competing technologies. The technology we are proposing used coupled arrays of 1550 nm vertical cavity surface emitting lasers for transmission. The feasibility of coupling these arrays together, to form coherent high-power beams that can be modulated at data rates exceeding 1 Gbps, will be explored. We will propose an architecture that enables electronic beam steering, thus mitigating the need for ancillary acquisition, tracking and beam pointing equipment such as needed for current optical communicatin systems. The beam-steering capability we are proposing also opens the possibility of using this technology for inter-satellite communicatin links, and satellite-to-surface links.

Mueller, Carl H.↗

Development and validation of the cavitation-induced erosion risk assessment tool

This work presents the development of a cavitation-induced erosion risk assessment (CIERA) tool that links multiphase flow simulation predictions with the progress towards material erosion. To develop a robust erosion modeling tool, the cavitation and erosion predictions for pressurized diesel fuel flow within a channel geometry were validated over a range of Reynolds and cavitation number conditions in two different aluminum channel geometries, one featuring a rounded inlet corner and the other with a sharp inlet corner. The multiphase flow development within the channel was modeled using a compressible mixture model, where phase change was represented with the homogeneous relaxation model and the turbulent flow evolution was modeled using a dynamic structure approach for Large Eddy Simulations. To improve representation of the incubation period before material rupture over existing approaches, a physics-based metric was derived based on the cumulative energy absorbed by the solid material from repeated hydrodynamic impacts. When the average peak pressure was related to the incubation period, the incubation period and its sensitivity to changes in flow conditions were found to be overpredicted. In contrast, predictions from CIERA provided a more accurate means to qualitatively and quantitatively predict the influence of flow conditions on the incubation period before material erosion. When the predicted stored energy was related to the solid material properties to estimate the incubation period, multiphase flow simulations demonstrated accurate representation of the sensitivity of erosion severity to changes in flow conditions. The use of CIERA led to quantitative agreement of the predicted incubation period within 5% of the experimentally measured incubation period.

42 ENGINEERING↗

Mechanically robust and reprocessable imine exchange networks from modular polyester pre-polymers

Covalent adaptable networks (CANs) containing reversible cross-links impart recyclability to thermoset materials without sacrificing their desirable properties (e.g. high tensile strength and solvent resistance). In addition to thermal recycling, the sustainability of these materials may be further improved by incorporating bio-sourced monomers or by enabling alternate end-of-life fates, such as biodegradation or recovery of starting materials. The alternating ring-opening copolymerisation of epoxides and cyclic anhydrides permits the modular synthesis of polyester pre-polymers that can then be cross-linked to form dynamic imine-linked networks. In this work, we report the synthesis and characterisation of five imine exchange polyester CANs with varied cross-linking densities and pre-polymer architectures. While the materials exhibit characteristic thermoset properties at service temperatures, differences in pre-polymer architecture produce distinct dynamic mechanical effects at elevated temperatures. The networks may be thermally reprocessed with full recovery of their tensile strengths and cross-linking densities, dissociated to pre-polymer, or hydrolytically degraded.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

An Atmospheric Tape Recorder: The Imprint of Tropical Tropopause Temperatures on Stratospheric Water Vapor

We describe observations of tropical stratospheric water vapor q that show clear evidence of large-scale upward advection of the signal from annual fluctuations in the effective 'entry mixing ratio' q(sub E) of air entering the tropical stratosphere. In other words, air is 'marked,' on emergence above the highest cloud tops, like a signal recorded on an upward moving magnetic tape. We define q(sub E) as the mean water vapor mixing ratio, at the tropical tropopause, of air that will subsequently rise and enter the stratospheric 'overworld' at about 400 K. The observations show a systematic phase lag, increasing with altitude, between the annual cycle in q(sub E) and the annual cycle in q at higher altitudes. The observed phase lag agrees with the phase lag calculated assuming advection by the transformed Eulerian-mean vertical velocity of a q(sub E) crudely estimated from 100-hPa temperatures, which we use as a convenient proxy for tropopause temperatures. The phase agreement confirms the overall robustness of the calculation and strongly supports the tape recorder hypothesis. Establishing a quantitative link between q(sub E) and observed tropopause temperatures, however, proves difficult because the process of marking the tape depends subtly on both small- and large-scale processes. The tape speed, or large-scale upward advection speed, has a substantial annual variation and a smaller variation due to the quasi-biennial oscillation, which delays or accelerates the arrival of the signal by a month or two in the middle stratosphere. As the tape moves upward, the signal is attenuated with an e-folding time of about 7 to 9 months between 100 and 50 hPa and about 15 to 18 months between 50 and 20 hPa, constraining possible orders of magnitude both of vertical diffusion K(sub z) and of rates of mixing in from the extratropics. For instance, if there were no mixing in, then K(sub z) would be in the range 0.03-0.09 m(exp 2)/s; this is an upper bound on K(sub z).

Mote, Philip W.↗

Spacesuit Evaporator-Absorber-Radiator (SEAR)

For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

Bue, Grant C.↗