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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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Direct vs. Indirect Control Schemes for Grid-Forming Inverters–Unveiling a Performance Comparison in a Microgrid
Not Available
Validation of Transmission Loss Simulation Approach with Goal to Estimate Launch Vehicle Internal Cavity Acoustics
No abstract available
Digitalization of an experimental electrochemical reactor via the smart manufacturing innovation platform
The exponential increase in data produced over the last two decades has revolutionized the way we collect, store, process, analyze, model, and interpret information to improve profitability. Manufacturing is no exception. How- ever, Smart Manufacturing, the digital practice, organization, workforce, and infrastructure transformation for collection and deployment of data and models at scale and at all levels of manufacturing, is a complex, costly, and labor-intensive journey that is still seeing slow adoption. The Clean Energy Smart Manufacturing Innovation Institute (CESMII), a national Manufacturing USA public-private partnership sponsored by the Department of Energy, is addressing this scaled use of data and modeling in manufacturing. CESMII has focused on how to col- lect and use operating data for numerous applications that improve productivity, precision, and performance of manufacturing operations from factory floor to supply chain using process simulation, predictive analytics, mon- itoring and control, and real-time optimization. Because contextualized data are key, CESMII has developed the Smart Manufacturing Innovation Platform (SMIP) to lower the barriers to the data that are needed to accelerate data-based model building, improve data visualization, and more quickly gain insights. Reusable, standards-based ways of doing data collection, ingestion, and contextualization are particularly important for scaling access and use of data. The SMIP uses a standards-based definition and construct for reusable information models called an SM Profile. When an SM Profile is used in conjunction with the SMIP, the SMIP ensures the availability of contextualized, operational data for model building. The present work demonstrates Smart Manufacturing and the application of the SMIP for building several data-centered models for the operation and control of an ex- perimental electrochemical reactor that reduces carbon dioxide (CO 2 ) gas to valuable liquid and gas chemicals, such as alcohols, olefins, and syngas. We describe how the SMIP plays a central role in more effective model building and we demonstrate how the electochemical reactor can be controlled and optimized for the desired products. Use of the SMIP involves the transmission of real-time sensor measurements to a cloud resource so that the operating data are available to all model building experts. The data collection and transmission process is fully automated to greatly reduce the need for manual manipulation of the data. Data-driven machine learning models are used for advanced real-time state estimation, real-time optimization, and model-based feedback control for the reactor. The application models are implemented as a system to monitor the data flow and control the electrochemical reactor with a single visualization interface. SM Profiles are used to demonstrate reusability of the information models for the reactor and the instrumentation. The application packages, algorithms, and user interfaces developed are cast as Docker images in a library to facilitate reusability of the application models.
Reliability-Informed Life-Cycle Warranty Cost Analysis: A Case Study on a Transmission in Agricultural Equipment
In agricultural and industrial equipment, both new and remanufactured systems are often available for warranty coverage. In such cases, it may be challenging for equipment manufacturers to properly trade-off between the system reliability and the cost associated with a replacement option (e.g., replace with a new or remanufactured system). To address this problem, we present a reliability-informed life-cycle warranty cost (LCWC) analysis framework that enables equipment manufacturers to evaluate different warranty policies. These warranty policies differ in whether a new or remanufactured system is used for replacement in the case of product failure. The novelty of this LCWC analysis framework lies in its ability to incorporate real-world field reliability data into warranty policy assessment using probabilistic warranty cost models that consider multiple life cycles. First, the reliability functions for the new and remanufactured systems are built as the time-to-failure distributions that provide the best-fit to the field reliability data. Then, these reliability functions and their corresponding warranty policies are used to build the LCWC models according to the specific warranty terms. Finally, Monte Carlo simulation is used to propagate the time-to-failure uncertainty of each system, modeled by its reliability function, through each LCWC model to produce a probability distribution of the LCWC. The effectiveness of the proposed reliability-informed LCWC analysis framework is demonstrated with a real-world case study on a transmission used in some agricultural equipment.
Performance of pumped counterflow virtual impactors to study aerosol interactions with laboratory generated warm clouds
Pumped Counterflow Virtual Impactors (PCVI) are designed to separate aerosols based on aerodynamic diameter, which is particularly useful for isolating cloud droplets and ice crystals from smaller particles. However, the PCVI transmission efficiency (TE) values reported in the literature show considerable variability, and little information is available on the TEs for cloud liquid droplets. Here, we determined the optimal flow conditions for PCVI sampling for different activation ratios from the MTU Pi-cloud chamber, highlighting the conditions that maximize droplet residual sampling while minimizing interstitial transmission. Even for a lower limit cloud activation ratio = 1:10, an add flow of 1.5 LPM achieves a residual fraction greater than 0.80, with a droplet TE of ∼15% for typical Pi-Chamber droplets with diameters between 3.5 to 10 µm. This framework can be adapted for field cloud measurements based on the cloud conditions of interest. TE for cloud droplets under flow conditions at which ∼99% of the unactivated submicron particles were removed was substantially lower between 8 and 16% than for supermicron dry particles (∼30 to 40% for 3 µm polystyrene latex spheres). In addition, we conducted a comparison of the performances of three similar PCVI units to assess repeatability for dry aerosols and cloud droplets. All three PCVIs performed similarly in rejecting submicron particles smaller than the desired cutoff diameter. One of the units showed lower TEs due to a misalignment of the internal orifice. We discuss a procedure that improved alignment and performance.
Electric sector impacts of renewable policy coordination: A multi-model study of the North American energy system
Not Available
Nanoscale oxidation behavior of carbon fibers revealed with in situ gas cell STEM
Thermal protection systems are used to protect spacecraft payloads during the extreme conditions of atmospheric entry. The backbone of the composite material often used for NASA mission is carbon fiber, which oxidizes at these conditions. This study presents the direct observation of carbon oxidation using in situ Scanning Transmission Electron Microscopy (STEM). A thin section of a commercially-available carbon fiber material containing multiple structures was examined by STEM in a closed-environmental cell in which temperature was raised from 25 to 1050 °C under a steady flow of air. Results show that the random polycrystalline carbon structure oxidized more uniformly and rapidly than the single crystallite region, which oxidized more anisotropically. These findings are the first to directly observe the structural dependence of carbon oxidation rates at these length-scales while also giving important insight into the onset of pitting at various active surface sites, important pieces in fundamentally understanding of carbon oxidation.
The Completed SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations with Ly$α$ Forests
Here, we present a measurement of baryonic acoustic oscillations (BAO) from Lyman-α (Lyα) absorption and quasars at an effective redshift $z = 2.33$ using the complete extended Baryonic Oscillation Spectroscopic Survey (eBOSS). The sixteenth and final eBOSS data release (SDSS DR16) contains all data from eBOSS and its predecessor, the Baryonic Oscillation Spectroscopic Survey (BOSS), providing 210,005 quasars with $z_q > 2.10$ that are used to measure Lyα absorption. We measure the BAO scale both in the auto-correlation of Ly$α$ absorption and in its cross correlation with 341,468 quasars with redshift $z_q > 1.77$. Apart from the statistical gain from new quasars and deeper observations, the main improvements over previous work come from more accurate modeling of physical and instrumental correlations and the use of new sets of mock data. Combining the BAO measurement from the auto- and cross-correlation yields the constraints of the two ratios $D_H(z = 2.33)/r_d = 8.99 ± 0.19$ and $D_M(z = 2.33)/r_d = 37.5 ± 1.1$, where the error bars are statistical. These results are within $1.5σ$ of the prediction of the flat-ΛCDM cosmology of Planck (2016). The analysis code, picca, the catalog of the flux-transmission field measurements, and the $Δ\chi^2$ surfaces are publicly available.
Single mode glass fiber welding
The electric-arc welding of commercially available single-mode optical fiber has been demonstrated. A mean transmission of 92% and a maximum transmission of 98% are reported for welds of fiber waveguide of 4.5 microns core diameter.
Large rotorcraft transmission technology development program
Testing of a U.S. Army XCH-62 HLH aft rotor transmission under NASA Contract NAS 3-22143 was successfully completed. This test establishes the feasibility of large, high power rotorcraft transmissions as well as demonstrating the resolution of deficiencies identified during the HLH advanced technology programs and reported by USAAMRDLTR-77-38. Over 100 hours of testing was conducted. At the 100% design power rating of 10,620 horsepower, the power transferred through a single spiral bevel gear mesh is more than twice that of current helicopter bevel gearing. In the original design of these gears, industry-wide design methods were employed and failures were experienced which identified problem areas unique to gear size. To remedy this technology shortfall, a program was developed to predict gear stresses using finite element analysis for complete and accurate representation of the gear tooth and supporting structure. To validate the finite element methodology gear strain data from the existing U.S. Army HLH aft transmission was acquired, and existing data from smaller gears were made available.
Non-linear dynamics of a geared rotor-bearing system with multiple clearances
The nonlinear frequency response characteristics of a geared rotor-bearing system are examined. A three-DOF dynamic model is developed which includes nonlinearities associated with radial clearances in the radial rolling element bearings and backlash between a spur gear pair; linear time-invariant gear meshing stiffness is assumed. The corresponding linear system problem is also solved, and predicted natural frequencies and modes match with finite element method results. The applicability of both analytical and numerical solution techniques to the multi-DOF nonlinear problem is investigated. Satisfactory agreement is found between the theory presented here and the available experimental data. Nonlinear modal interactions and differences between internal static transmission error excitation and external torque excitation are discussed. In addition, parametric studies are performed to understand the effect of system parameters such as bearing stiffness to gear mesh stiffness ratio, alternating to mean force ratio and radial bearing preload to mean force ratio on the nonlinear dynamic behavior.
Modeling Molecular Opacities Using Galileo Probe Observations
Data from the Net Flux Radiometer (NFR) experiment on the Galileo mission has been successfully collected and analyzed through 1996. As data was received, the best available laboratory spectroscopic data and was used in the reduction procedure. Since then newer and more accurate spectroscopic data has become available. During this agreement, research efforts focused on re-analysis of certain aspects of the data which benefited from recent improvements in spectroscopic databases, and from a more exact treatment of certain aspects of the physical theory of line shape and line broadening. In addition, a brief survey was completed of the available information, both theoretical and observational, of the absorption, reflection and transmission spectra of the atmospheres of the various types of planets that could reasonably be expected to occur in other solar systems.
Modeling Molecular Opacities using Galileo Probe Observations
Data from the Net Flux Radiometer (NFR) experiment on the Galileo mission has been successfully collected and analyzed through 1996. As data was received, the best available laboratory spectroscopic data and was used in the reduction procedure. Since then newer and more accurate spectroscopic data has become available. During this agreement, research efforts focused on re-analysis of certain aspects of the data which benefited from recent improvements in spectroscopic databases, and from a more exact treatment of certain aspects of the physical theory of line shape and line broadening. In addition, a brief survey was completed of the available information, both theoretical and observational, of the absorption, reflection and transmission spectra of the atmospheres of the various types of planets that could reasonably be expected to occur in other solar systems.
PIMS-Universal Payload Information Management
As the overall manager and integrator of International Space Station (ISS) science payloads and experiments, the Payload Operations Integration Center (POIC) at Marshall Space Flight Center had a critical need to provide an information management system for exchange and management of ISS payload files as well as to coordinate ISS payload related operational changes. The POIC's information management system has a fundamental requirement to provide secure operational access not only to users physically located at the POIC, but also to provide collaborative access to remote experimenters and International Partners. The Payload Information Management System (PIMS) is a ground based electronic document configuration management and workflow system that was built to service that need. Functionally, PIMS provides the following document management related capabilities: 1. File access control, storage and retrieval from a central repository vault. 2. Collect supplemental data about files in the vault. 3. File exchange with a PMS GUI client, or any FTP connection. 4. Files placement into an FTP accessible dropbox for pickup by interfacing facilities, included files transmitted for spacecraft uplink. 5. Transmission of email messages to users notifying them of new version availability. 6. Polling of intermediate facility dropboxes for files that will automatically be processed by PIMS. 7. Provide an API that allows other POIC applications to access PIMS information. Functionally, PIMS provides the following Change Request processing capabilities: 1. Ability to create, view, manipulate, and query information about Operations Change Requests (OCRs). 2. Provides an adaptable workflow approval of OCRs with routing through developers, facility leads, POIC leads, reviewers, and implementers. Email messages can be sent to users either involving them in the workflow process or simply notifying them of OCR approval progress. All PIMS document management and OCR workflow controls are coordinated through and routed to individual user's "to do" list tasks. A user is given a task when it is their turn to perform some action relating to the approval of the Document or OCR. The user's available actions are restricted to only functions available for the assigned task. Certain actions, such as review or action implementation by non-PIMS users, can also be coordinated through automated emails.
Multitemporal Cross-Calibration of the Terra MODIS and Landsat 7 ETM+ Reflective Solar Bands
In recent years, there has been a significant increase in the use of remotely sensed data to address global issues. With the open data policy, the data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Enhanced Thematic Mapper Plus (ETM+) sensors have become a critical component of numerous applications. These two sensors have been operational for more than a decade, providing a rich archive of multispectral imagery for analysis of mutitemporal remote sensing data. This paper focuses on evaluating the radiometric calibration agreement between MODIS and ETM+ using the near-simultaneous and cloud-free image pairs over an African pseudo-invariant calibration site, Libya 4. To account for the combined uncertainties in the top-of-atmosphere (TOA) reflectance due to surface and atmospheric bidirectional reflectance distribution function (BRDF), a semiempirical BRDF model was adopted to normalize the TOA reflectance to the same illumination and viewing geometry. In addition, the spectra from the Earth Observing-1 (EO-1) Hyperion were used to compute spectral corrections between the corresponding MODIS and ETM+ spectral bands. As EO-1 Hyperion scenes were not available for all MODIS and ETM+ data pairs, MODerate resolution atmospheric TRANsmission (MODTRAN) 5.0 simulations were also used to adjust for differences due to the presence or lack of absorption features in some of the bands. A MODIS split-window algorithm provides the atmospheric water vapor column abundance during the overpasses for the MODTRAN simulations. Additionally, the column atmospheric water vapor content during the overpass was retrieved using the MODIS precipitable water vapor product. After performing these adjustments, the radiometric cross-calibration of the two sensors was consistent to within 7%. Some drifts in the response of the bands are evident, with MODIS band 3 being the largest of about 6% over 10 years, a change that will be corrected in Collection 6 MODIS processing.
Silicon Technologies Adjust to RF Applications
Silicon (Si), although not traditionally the material of choice for RF and microwave applications, has become a serious challenger to other semiconductor technologies for high-frequency applications. Fine-line electron- beam and photolithographic techniques are now capable of fabricating silicon gate sizes as small as 0.1 micron while commonly-available high-resistivity silicon wafers support low-loss microwave transmission lines. These advances, coupled with the recent development of silicon-germanium (SiGe), arm silicon integrated circuits (ICs) with the speed required for increasingly higher-frequency applications.