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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Optical Software Defined Radio Transmitter Extinction Ratio Enhancement with Differential Pulse Carving

A unique challenge in the development of a deep space optical software defined radio (SDR) transmitter is the optimization of the extinction ratio (ER). For a Mars to Earth optical link, an ER approaching 40dB may be necessary. However, a high ER can be difficult to achieve at the low PPM orders and narrow slot widths required for high data rates. The quality of the digital signal transmitted by the SDR does not meet the amplitude and timing characteristics needed by an analog optical modulator. The conflicting implementation constraints of these two fundamentally different systems, the digital SDR and analog optical modulator, can make achieving the required ER very difficult. In this paper, the causes of fidelity loss at the interface between the SDR and optical modulator are discussed. The SDR signal quality requirements are derived and explored. It is shown that increasing the SDR signal quality enough to meet these requirements is impractical to implement due to bandwidth limitations of electronic components as well as Field Programmable Gate Array (FPGA) clock speed constraints. A novel optical modulation architecture based on low-voltage differential signaling and dual Mach-Zehnder modulators is presented which reduces the signal quality requirements on the SDR and increases the system ER.

Electro-Optic Modulator↗
NASA NTRS2019

Optical Software Defined Radio Transmitter Extinction Ratio Enhancement with Differential Pulse Carving

A unique challenge in the development of a deep space optical software defined radio (SDR) transmitter is the optimization of the extinction ratio (ER). For a Mars to Earth optical link, an ER approaching 40dB may be necessary. However, a high ER can be difficult to achieve at the low PPM orders and narrow slot widths required for high data rates. The quality of the digital signal transmitted by the SDR does not meet the amplitude and timing characteristics needed by an analog optical modulator. The conflicting implementation constraints of these two fundamentally different systems, the digital SDR and analog optical modulator, can make achieving the required ER very difficult. In this paper, the causes of fidelity loss at the interface between the SDR and optical modulator are discussed. The SDR signal quality requirements are derived and explored. It is shown that increasing the SDR signal quality enough to meet these requirements is impractical to implement due to bandwidth limitations of electronic components as well as Field Programmable Gate Array (FPGA) clock speed constraints. A novel optical modulation architecture based on low-voltage differential signaling and dual Mach-Zehnder modulators is presented which reduces the signal quality requirements on the SDR and increases the system ER.

Electro-Optic Modulator↗
NASA NTRS2012

On Approaching the Ultimate Limits of Communication Using a Photon-Counting Detector

Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement scheme is as of yet unknown, and it is also likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We analyze two binary modulation architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with the state-of-the-art coherent-state on-off keying modulation. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff--determined by the Holevo capacity--by only a constant factor. The first architecture we analyze is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.

photon-counting measurement↗
DOE OSTI2023

WhatsCracking [SWR-23-03]

WhatsCracking can accurately predict cell fracture in crystalline silicon PV modules. The probability of PV module cell fracture is determined by a complicated interrelationship of module architecture, materials, and loading. WhatsCracking is a Finite Element Method tool which enables users to assess how module design impacts the propensity for cell fracture.

Deceglie, Michael↗
NASA NTRS2011

Optimized Biasing of Pump Laser Diodes in a Highly Reliable Metrology Source for Long-Duration Space Missions

Non Planar Ring Oscillator (NPRO) lasers are highly attractive for metrology applications. NPRO reliability for prolonged space missions is limited by reliability of 808 nm pump diodes. Combined laser farm aging parameter allows comparing different bias approaches. Monte-Carlo software developed to calculate the reliability of laser pump architecture, perform parameter sensitivity studies To meet stringent Space Interferometry Mission (SIM) Lite lifetime reliability / output power requirements, we developed a single-mode Laser Pump Module architecture that: (1) provides 2 W of power at 808 nm with >99.7% reliability for 5.5 years (2) consists of 37 de-rated diode lasers operating at -5C, with outputs combined in a very low loss 37x1 all-fiber coupler

laser communications↗
DOE OSTI2025

Structure–Function Relationships in Sequence-Controlled Copolymers for Rare Earth Element Chelation

The ability to tune material function through primary sequence is a defining feature of biological macromolecules, allowing precise control over structure and target interactions in complex aqueous environments. However, translating sequence–structure–function relationships to synthetic macromolecules is challenging due to their dispersity in sequence, conformation, and composition. Here, we report systematic studies of amphiphilic polymer chelators designed to probe how composition and patterning influence binding affinity and selectivity for rare earth elements (REEs), a series of technologically relevant metals with challenging separation profiles. A library of copolymers varying hydrophobic monomer composition and patterning was synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization, spanning statistical, gradient, and block architectures. REE binding was quantified using a high-throughput colorimetric assay, and reconstruction of polymer ensembles using kinetic stochastic simulations enabled quantitative comparisons of sequence heterogeneity, linking local monomer colocalization to emergent REE binding. Further, we investigated the role of different hydrophobic comonomers in tuning metal coordination, with binding trends linked to structural features that influence binding site desolvation. Complementary dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements showed that both polymer and monomer architecture modulate metal-induced conformational changes, and that multichain assembly behavior emerges beyond critical hydrophobic thresholds. Sequence control also altered REE selectivity, with nonmonotonic differences observed across compositionally identical polymers with different sequence architectures. Together, these findings establish design principles that connect polymer sequence and structure to binding performance, guiding the design of macromolecular chelators with enhanced affinity and selectivity for applications in separations, sensing, and catalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1993

Current state of the mass storage system reference model

IEEE SSSWG was chartered in May 1990 to abstract the hardware and software components of existing and emerging storage systems and to define the software interfaces between these components. The immediate goal is the decomposition of a storage system into interoperable functional modules which vendors can offer as separate commercial products. The ultimate goal is to develop interoperable standards which define the software interfaces, and in the distributed case, the associated protocols to each of the architectural modules in the model. The topics are presented in viewgraph form and include the following: IEEE SSSWG organization; IEEE SSSWG subcommittees & chairs; IEEE standards activity board; layered view of the reference model; layered access to storage services; IEEE SSSWG emphasis; and features for MSSRM version 5.

Coyne, Robert↗
DOE OSTI2022

Fast External Quantum Efficiency Measurements of Photovoltaic Modules

The external quantum efficiency (EQE) or associated spectral response is widely used to evaluate the performance of photovoltaics, light emitting diodes, photodetectors, photodiodes, semiconductor lasers, laser-induced refrigeration of solids etc. For photovoltaic (PV) devices, The EQE is used to determine the spectral mismatch correction that is used to convert a performance measurement from a non-ideal simulator spectrum to a standard spectrum in PV device calibrations. Moreover, EQE can provide important insight into the physics of a PV device. For instance, the EQE shape can be used to infer mechanisms limiting the performance of the device. However, EQE measurements of full-size PV modules remain a challenge in the PV community due to rare availability of reliable module QE measurement tools worldwide and the size and complexity of module architecture that comprises several cells connected in strings (series or/and parallel). Here, we use a customized nondestructive tool made of high-power light emitting diodes to perform high-throughput EQE measurements on PV modules. Circuit simulations show that the measurement system can safely be used to measure both crystalline silicon and thin film-based PV modules with series connected cells without the risk of damage through reverse bias. In addition, EQE mapping combined with electroluminescence show a strong correlation and provide a way to determine both spatial non-uniformity of the spectral response and defects/degradation effects across the module.

PV module↗
NASA NTRS2017

Kilo-Pixel Miniaturized Thermal Imagers based on Advanced Thermoelectrics

This work presents a novel focal plane module architecture based on kilo-pixel arrays able to image from UV to far-infrared scenes. The focal plane arrays are integrated with custom-made, chopper-stabilized read-out integrated circuits into sub-assembly modules to be mounted on the optical telescope of the instrument.

Johnson, William↗
NASA NTRS1993

Advanced Launch System Multi-Path Redundant Avionics Architecture Analysis and Characterization

The objective of the Multi-Path Redundant Avionics Suite (MPRAS) program is the development of a set of avionic architectural modules which will be applicable to the family of launch vehicles required to support the Advanced Launch System (ALS). To enable ALS cost/performance requirements to be met, the MPRAS must support autonomy, maintenance, and testability capabilities which exceed those present in conventional launch vehicles. The multi-path redundant or fault tolerance characteristics of the MPRAS are necessary to offset a reduction in avionics reliability due to the increased complexity needed to support these new cost reduction and performance capabilities and to meet avionics reliability requirements which will provide cost-effective reductions in overall ALS recurring costs. A complex, real-time distributed computing system is needed to meet the ALS avionics system requirements. General Dynamics, Boeing Aerospace, and C.S. Draper Laboratory have proposed system architectures as candidates for the ALS MPRAS. The purpose of this document is to report the results of independent performance and reliability characterization and assessment analyses of each proposed candidate architecture and qualitative assessments of testability, maintainability, and fault tolerance mechanisms. These independent analyses were conducted as part of the MPRAS Part 2 program and were carried under NASA Langley Research Contract NAS1-17964, Task Assignment 28.

Baker, Robert L.↗
DOE OSTI2025

Design, Fabrication and On-Sun Performance Evaluation of SiC Receiver Feature Specimens for CST Applications Using Additively Manufactured SiC Materials

Increasing operating temperatures of solar receivers is paramount to the efficiency of concentrated solar thermal (CST) and solar power (CSP) systems. Successful development of CST systems to generate heat for industrial applications requires significant increase in temperature capability and techno-economically viability of the receiver systems. Supported by an award from the Solar Technology Office (SETO), US Department of Energy (DOE), GE Aerospace Research in collaboration with Heliogen Holdings Inc and Sandia National Lab, is engaged in the development of ultra-High Operating Temperature SiC-matrix Solar Thermal Air Receiver (HOTSSTAR) enabled by additive manufacturing. The program objective is to demonstrate SiC receiver with air exit temperatures up to 1100 oC and high thermal efficiencies. We report design, fabrication and on-sun test results of SiC components of a prototype 50kW (thermal) HOTSSTAR module. The receiver module architecture is based on a radial airflow design and consists of a series of radial SiC receiver sectors organized around a SiC center absorber. The SiC components are fabricated using binder-jet printed SiC followed by melt-infiltration reaction bonding process. To enhance the reliability and to minimize the risk of cracking damage of SiC test articles in thermal gradient and thermal shock environment of the application, the components were laminated with GE’s MI SiC-SiC CMC. Following extensive design and lab test analyses, selected SiC component designs are tested at Heliogen Lancaster Solar field under highly concentrated solar fluxes around 2000 suns to assess the thermal performance characteristics under realistic field conditions. We report on the test results and compare the thermal performances of different HOTSSTAR SiC absorbers. Finally, we discuss fabrication and initial assembly of a 50kW prototype test module in preparation of on-sun field tests to assess the performance of our final design.

CST, CSP, high temperature, air receiver, SiC, add↗
DOE OSTI2022

Evaluation of PV Module Packaging Strategies of Monofacial and Bifacial PERC Using Degradation Pathway Network Modeling

As the PV industry is rapidly expanding, it is important to thoroughly investigate the long-term impact of packaging strategies on the performance of PV modules. In this study, the variants in sets differ on the basis of manufacturer (A/B), encapsulant (EVA/POE), rear encapsulant (UV-cutoff/opaque/transparent), module architecture (GB/DG) and cell type (monofacial/bifacial). The minimodules were exposed for 2520 hours in modified damp heat, with or without full spectrum light. Every 504 hours, stepwise electrical characterization techniques were employed to track changes in minimodules. Degradation pathway modeling using network structural equation modeling was employed to study pairwise relationships between variables and service lifetime prediction in minimodules. Through this study, differences in quality control are identified in minimodules made by different manufacturers. Minimodules with UV-cutoff rear encapsulant show relatively better stability, whereas the ones with opaque rear encapsulant show greater power loss. In addition, GB having UV-cutoff rear encapsulation and GB with POE having opaque rear encapsulation were identified to be stable as they lack a best model fit. Here, the primary power loss mechanism in degrading variants is interconnect corrosion.

14 SOLAR ENERGY↗
DOE OSTI2021

Thermomechanical fatigue resistance of low temperature solder for multiwire interconnects in photovoltaic modules

Novel interconnect technologies leveraging low melting temperature solders, such as multiwire interconnects, are being deployed in photovoltaic (PV) modules for improved reliability through interconnect redundancy and lower thermal loads during interconnection and lamination. However, the equivalency of standardized accelerated testing to field conditions has not yet been established for these emerging technologies. In this study, the thermomechanical fatigue resistance of low temperature solder alloys is investigated and compared to that of conventional SnPb to assess the acceleration behavior of these alloys. While InSn is shown to have sufficient thermomechanical fatigue resistance on the order of that of SnPb, these results indicate Sn–Bi alloys may have poor thermomechanical fatigue resistance at field conditions. The results also show that Sn–Bi alloys have thermal cycling acceleration factors of less than one. This indicates that the standardized accelerated thermal cycling test, such as that in IEC 61215, will produce misleading results for Sn–Bi alloys and that unique testing is required for this PV module architecture. Though accelerated thermal cycling may be a meaningful qualification test for SnPb solder joints, these results suggest that mechanical loading may be a more appropriate test for Sn–Bi multiwire interconnects. This is due to the distinct processing and geometry of multiwire interconnects which may allow for mechanical, rather than strictly metallurgical interconnections.

14 SOLAR ENERGY↗
DOE OSTI2023

Expression quantitative trait loci mapping identified PtrXB38 as a key hub gene in adventitious root development in Populus

Summary Plant establishment requires the formation and development of an extensive root system with architecture modulated by complex genetic networks. Here, we report the identification of the PtrXB38 gene as an expression quantitative trait loci (eQTL) hotspot, mapped using 390 leaf and 444 xylem Populus trichocarpa transcriptomes. Among predicted targets of this trans ‐eQTL were genes involved in plant hormone responses and root development. Overexpression of PtrXB38 in Populus led to significant increases in callusing and formation of both stem‐born roots and base‐born adventitious roots. Omics studies revealed that genes and proteins controlling auxin transport and signaling were involved in PtrXB38‐mediated adventitious root formation. Protein–protein interaction assays indicated that PtrXB38 interacts with components of endosomal sorting complexes required for transport machinery, implying that PtrXB38‐regulated root development may be mediated by regulating endocytosis pathway. Taken together, this work identified a crucial root development regulator and sheds light on the discovery of other plant developmental regulators through combining eQTL mapping and omics approaches.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

A High Power Density and High Efficiency Traction Drive Based on a Segmented Inverter and an Axial and Radial Flux Hybrid Machine

Eaton Corporation and Oak Ridge National Laboratory (ORNL) collaborated to develop a high performance traction drive system aimed at increasing power density and overall efficiency. The system integrates Eaton’s hybrid flux motor—combining radial and axial flux paths to convert end-winding and structural elements into torque-producing components—with ORNL’s high-power-density segmented inverter. This motor design achieves higher torque density within the same footprint as traditional radial flux machines by effectively utilizing end turns. ORNL’s segmented inverter reduces the DC bus capacitor requirement by over 50% compared to standard voltage source inverters (VSIs), achieving power densities exceeding 100 kVA/L. The dual-module architecture also enables six-phase operation, aligning with Eaton’s motor design. Together, the motor and inverter offer a compact, efficient traction drive system with the potential for significant reductions in system weight and improvements in powertrain efficiency.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1984

Configuration study for a 30 GHz monolithic receive array, volume 1

Gregorian, Cassegrain, and single reflector systems were analyzed in configuration studies for communications satellite receive antennas. Parametric design and performance curves were generated. A preliminary design of each reflector/feed system was derived including radiating elements, beam-former network, beamsteering system, and MMIC module architecture. Performance estimates and component requirements were developed for each design. A recommended design was selected for both the scanning beam and the fixed beam case. Detailed design and performance analysis results are presented for the selected Cassegrain configurations. The final design point is characterized in detail and performance measures evaluated in terms of gain, sidelobe level, noise figure, carrier-to-interference ratio, prime power, and beamsteering. The effects of mutual coupling and excitation errors (including phase and amplitude quantization errors) are evaluated. Mechanical assembly drawings are given for the final design point. Thermal design requirements are addressed in the mechanical design.

Nester, W. H.↗
NASA NTRS1988

Automatic acquisition of domain and procedural knowledge

The design concept and performance of AKAS, an automated knowledge-acquisition system for the development of expert systems, are discussed. AKAS was developed using the FLES knowledge base for the electrical system of the B-737 aircraft and employs a 'learn by being told' strategy. The system comprises four basic modules, a system administration module, a natural-language concept-comprehension module, a knowledge-classification/extraction module, and a knowledge-incorporation module; details of the module architectures are explored.

Ferber, H. J.↗
NASA NTRS1990

Space Station module Power Management And Distribution (PMAD) system

This project consists of several tasks which are unified toward experimentally demonstrating the operation of a highly autonomous, user-supportive power management and distribution system for Space Station Freedom (SSF) habitation/laboratory modules. This goal will be extended to a demonstration of autonomous, cooperative power system operation for the whole SSF power system through a joint effort with NASA's Lewis Research Center, using their Autonomous Power System. Short term goals for the space station module power management and distribution include having an operational breadboard reflecting current plans for SSF, improving performance of the system communications, and improving the organization and mutability of the artificial intelligence (AI) systems. In the middle term, intermediate levels of autonomy will be added, user interfaces will be modified, and enhanced modeling capabilities will be integrated in the system. Long term goals involve conversion of all software into Ada, vigorous verification and validation efforts and, finally, seeing an impact of this research on the operation of SSF. Conversion of the system to a DC Star configuration is now in progress, and should be completed by the end of October, 1989. This configuration reflects the latest SSF module architecture. Hardware is now being procured which will improve system communications significantly. The Knowledge-Based Management System (KBMS) is initially developed and the rules from FRAMES have been implemented in the KBMS. Rules in the other two AI systems are also being grouped modularly, making them more tractable, and easier to eventually move into the KBMS. Adding an intermediate level of autonomy will require development of a planning utility, which will also be built using the KBMS. These changes will require having the user interface for the whole system available from one interface. An Enhanced Model will be developed, which will allow exercise of the system through the interface without requiring all of the power hardware to be operational. The functionality of the AI systems will continue to be advanced, including incipient failure detection. Ada conversion will begin with the lowest level processor (LLP) code. Then selected pieces of the higher level functionality will be recorded in Ada and, where possible, moved to the LLP level. Validation and verification will be done on the Ada code, and will complete sometimes after completion of the Ada conversion.

Walls, Bryan↗