Enhanced calcium–magnesium–aluminosilicate (CMAS) resistance of GdAlO 3 (GAP) for composite thermal barrier coatings
Not provided.
Materials Science↗
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Results for “environmental degradation”
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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Deconstructing laws of accessibility and facility distribution in cities
The era of the automobile has seriously degraded the quality of urban life through costly travel and visible environmental effects. A new urban planning paradigm must be at the heart of our road map for the years to come, the one where, within minutes, inhabitants can access their basic living needs by bike or by foot. In this work, we present novel insights of the interplay between the distributions of facilities and population that maximize accessibility over the existing road networks. Results in six cities reveal that travel costs could be reduced in half through redistributing facilities. In the optimal scenario, the average travel distance can be modeled as a functional form of the number of facilities and the population density. As an application of this finding, it is possible to estimate the number of facilities needed for reaching a desired average travel distance given the population distribution in a city.
42 ENGINEERING↗
Data for Root Exudation Links Root Traits to Soil Functioning in Agroecosystems
Root exudation is a key process for plant nutrient acquisition, but the controls on root exudation and its relationship to soil C and N processes in agroecosystems are unclear. We hypothesized that root exudation rates would be related to root morphological traits, N fertilization, and soil moisture. We also anticipated that root exudation would be correlated with bulk soil enzyme activity. Root exudation, root traits, and bulk soil extracellular enzyme activity were assessed in maize (Zea mays L.), soybean (Glycine max (L.) Merr.), biomass sorghum (Sorghum bicolor (L.) Moench), giant miscanthus (Miscanthus × giganteus), and switchgrass (Panicum virgatum L.). Measurements were taken in situ during two growing seasons with contrasting precipitation regimes, and N fertilization rate was varied in sorghum during one year. Specific root exudation (per unit root surface area) was negatively related to root diameter and was generally higher in annuals than perennials. Sorghum N fertilization did not affect root exudation rates, and soil moisture regime had no effect on annual root exudation rates within maize, sorghum, and miscanthus. Specific root exudation was negatively related to bulk soil C- and N-degrading soil enzyme activities. Intrinsic plant characteristics appeared more important than environmental variables in controlling in situ root exudation rates. The relationships between root diameter, root exudation, and soil C and N processes link root morphological traits to soil functions and demonstrate the potential tradeoffs among plant nutrient acquisition strategies in agroecosystems.
Biomass Analytics↗
Nickel-incorporated Oxide Composites for Fiber-Optic Based Gas Sensing
Numerous high-value applications within the energy sector involve environmental conditions that are incompatible with traditional sensor technology due to degradation of electrical interconnects, packaging, or the sensors themselves. These can include chemically harsh conditions, high temperature operation, or the presence of electromagnetic interference due to high voltage. The fiber optic platform, constructed of robust, electrically insulating glass or single crystal oxides, offers a versatile and often low cost per node solution to this problem, especially with the integration of distributed sensing techniques such as optical time-domain and frequency-domain reflectometry (OTDR, OFDR). A major challenge of gas and chemical sensing on the optical fiber platform is the fabrication of robust and stable sensing materials that interact quickly and reversibly to the presence of the target analytes. In this work, we discuss the utilization of nickel-incorporated oxides on evanescent-field optical fiber sensors for gas sensing under harsh conditions relevant to multiple energy infrastructure applications. This paper will discuss a Ni/GDC (Ni / Gd-doped ceria) based sensing layer targeting conditions relevant for high-temperature (up to at least 800 oC) hydrogen sensing applications (e.g., for operation within a solid oxide fuel cell or electrolyzer). The impact of hydrogen at elevated temperatures on the optical properties of Ni/GDC will be shown and the material mechanisms for the optical response will be discussed.
gas sensors↗
Long-Term Performance of Ag/AgCl Reference Electrodes for Corrosion Potential Monitoring in Radioactive Tank Waste at the Hanford Site
This work studied the exposure effects of radioactive tank waste on the long-term performance of single junction Ag/AgCl reference electrodes for corrosion potential monitoring at the Hanford Site. Electrodes from three manufacturers with very different designs were studied using open-circuit potential and electrochemical impedance measurements in radioactive tank waste. Post-test analyses were conducted on some failed electrodes using destructive and nondestructive techniques. The intrusion of the aggressive and radioactive chemicals in tank waste through the porous frit materials was the primary mechanism that led to the clogging of frit, physical and chemical degradation of AgCl bonded to Ag wire, and alteration of the internal electrolyte. Radiolytic chemical species such as H2O2 and HNO3 may have also induced the degradation of the Ag wire. The extent of electrode degradation and failure probability highly depended on the electrode design and environmental conditions. Chemicals in tank waste had stronger effects than radiation on the long-term performance of the Ag/AgCl reference electrodes.
Materials Science↗
High resolution, low cost solar cell contact development
The experimental work demonstrating the feasibility of the MIDFILM process as a low cost means of applying solar cell collector metallization as reported. Cell efficiencies of above 14% (AMl, 28 C) were achieved with fritted silver metallization. Environmental tests suggest that the metallization is slightly humidity sensitive and degradation is observed on cells with high series resistance. The major yield loss in the fabrication of cells was due to discontinuous grid lines, resulting in high series resitance. Standard lead-tin solder plated interconnections do not appear compatible with the MIDFILM contact. Copper, nickel and molybdemun base powder were investigated as low cost metallization systems. The copper based powder degraded the cell response. The nickel and molybdenum base powders oxidized when sintered in the oxidizing atmosphere necessary to ash the photoresin.
Mardesich, N.↗
A performance analysis study of a complex G field experiment
A performance analysis on data from an experiment which illustrates the degradation of tracking performance as the human is subjected to an environmental stressor is presented. The performance changes are defined and the statistical properties of human tracking with and without the stress effects examined. Performance is evaluated using an extension of a phase plane technique. A quantiative determination of stress effects on performance is defined explicitly in terms of parameters of a density function identified from the empirical data. The distribution functions which characterize tracking in a phase plane representation of the closed loop error signal are determined.
Repperger, D. W.↗
Plasma interactions with large spacecraft
Space is playing a rapidly expanding role in the conduct of the Air Force mission. Larger, more complex, high-power space platforms are planned and military astronauts will provide a new capability in spacecraft servicing. Interactions of operational satellites with the environment have been shown to degrade space sensors and electronics and to constrain systems operations. The environmental interaction effects grow nonlinearly with increasing size and power. Quantification of the interactions and development of mitigation techniques for systems-limiting interactions is essential to the success of future Air Force space operations.
Sagalyn, Rita C.↗
Sensor-Only System Identification for Structural Health Monitoring of Advanced Aircraft
Environmental conditions, cyclic loading, and aging contribute to structural wear and degradation, and thus potentially catastrophic events. The challenge of health monitoring technology is to determine incipient changes accurately and efficiently. This project addresses this challenge by developing health monitoring techniques that depend only on sensor measurements. Since actively controlled excitation is not needed, sensor-to-sensor identification (S2SID) provides an in-flight diagnostic tool that exploits ambient excitation to provide advance warning of significant changes. S2SID can subsequently be followed up by ground testing to localize and quantify structural changes. The conceptual foundation of S2SID is the notion of a pseudo-transfer function, where one sensor is viewed as the pseudo-input and another is viewed as the pseudo-output, is approach is less restrictive than transmissibility identification and operational modal analysis since no assumption is made about the locations of the sensors relative to the excitation.
Kukreja, Sunil L.↗
Reliability and Qualification of Hardware to Enhance the Mission Assurance of JPL/NASA Projects
Packaging Qualification and Verification (PQV) and life testing of advanced electronic packaging, mechanical assemblies (motors/actuators), and interconnect technologies (flip-chip), platinum temperature thermometer attachment processes, and various other types of hardware for Mars Exploration Rover (MER)/Mars Science Laboratory (MSL), and JUNO flight projects was performed to enhance the mission assurance. The qualification of hardware under extreme cold to hot temperatures was performed with reference to various project requirements. The flight like packages, assemblies, test coupons, and subassemblies were selected for the study to survive three times the total number of expected temperature cycles resulting from all environmental and operational exposures occurring over the life of the flight hardware including all relevant manufacturing, ground operations, and mission phases. Qualification/life testing was performed by subjecting flight-like qualification hardware to the environmental temperature extremes and assessing any structural failures, mechanical failures or degradation in electrical performance due to either overstress or thermal cycle fatigue. Experimental flight qualification test results will be described in this presentation.
PRTs↗
GOES-17 Advanced Baseline Imager Performance Recovery Summary
The 17th Geostationary Operational Environmental Satellite (GOES-17) was launched on 1 March 2018. The Advanced Baseline Imager (ABI) is the primary instrument on the GOES-R series for weather and environmental monitoring. The GOES-17 ABI (flight model 2) experienced a degradation in its thermal system that limits ABI's ability to shed solar heat load. This limitation resulted in significant reduction in performance after initial turn on with only 3 of 16 spectral channels expected to be available for much of the year. A combined government/vendor team was tasked with optimizing the operation of ABI to recapture as much performance as possible. By modifying the operational configuration and sensor parameters, the team was able to regain over 97% imaging capability.This was accomplished by taking advantage of the considerably flexible nature of ABI's design to adapt its configuration to the new reality and improve capabilities for many of ABI's subsystems. The significant differences in operational configuration, sensor parameter optimization, and algorithm optimization will be discussed as well as their impact on performance and data availability.
Advanced Baseline Imager↗
Nickel-incorporated Oxide Composites for Fiber-Optic Based Gas Sensing
Numerous high-value applications within the energy sector involve environmental conditions that are incompatible with traditional sensor technology due to degradation of electrical interconnects, packaging, or the sensors themselves. These can include chemically harsh conditions, high temperature operation, or the presence of electromagnetic interference due to high voltage. The fiber optic platform, constructed of robust, electrically insulating glass or single crystal oxides, offers a versatile and often low cost per node solution to this problem, especially with the integration of distributed sensing techniques such as optical time-domain and frequency-domain reflectometry (OTDR, OFDR). A major challenge of gas and chemical sensing on the optical fiber platform is the fabrication of robust and stable sensing materials that interact quickly and reversibly to the presence of the target analytes. In this work, we discuss the utilization of nickel-incorporated oxides on evanescent-field optical fiber sensors for gas sensing under harsh conditions relevant to multiple energy infrastructure applications. This paper will discuss a Ni/GDC (Ni / Gd-doped ceria) based sensing layer targeting conditions relevant for high-temperature (up to at least 800oC) hydrogen sensing applications (e.g., for operation within a solid oxide fuel cell or electrolyzer). The impact of hydrogen at elevated temperatures on the optical properties of Ni/GDC will be shown and the material mechanisms for the optical response will be discussed.
gas sensors↗
Degradation Reduces Microbial Richness and Alters Microbial Functions in an Australian Peatland
Abstract Peatland ecosystems cover only 3% of the world’s land area; however, they store one-third of the global soil carbon (C). Microbial communities are the main drivers of C decomposition in peatlands, yet we have limited knowledge of their structure and function. While the microbial communities in the Northern Hemisphere peatlands are well documented, we have limited understanding of microbial community composition and function in the Southern Hemisphere peatlands, especially in Australia. We investigated the vertical stratification of prokaryote and fungal communities from Wellington Plains peatland in the Australian Alps. Within the peatland complex, bog peat was sampled from the intact peatland and dried peat from the degraded peatland along a vertical soil depth gradient (i.e., acrotelm, mesotelm, and catotelm). We analyzed the prokaryote and fungal community structure, predicted functional profiles of prokaryotes using PICRUSt, and assigned soil fungal guilds using FUNGuild. We found that the structure and function of prokaryotes were vertically stratified in the intact bog. Soil carbon, manganese, nitrogen, lead, and sodium content best explained the prokaryote composition. Prokaryote richness was significantly higher in the intact bog acrotelm compared to degraded bog acrotelm. Fungal composition remained similar across the soil depth gradient; however, there was a considerable increase in saprotroph abundance and decrease in endophyte abundance along the vertical soil depth gradient. The abundance of saprotrophs and plant pathogens was two-fold higher in the degraded bog acrotelm. Soil manganese and nitrogen content, electrical conductivity, and water table level (cm) best explained the fungal composition. Our results demonstrate that both fungal and prokaryote communities are shaped by soil abiotic factors and that peatland degradation reduces microbial richness and alters microbial functions. Thus, current and future changes to the environmental conditions in these peatlands may lead to altered microbial community structures and associated functions which may have implications for broader ecosystem function changes in peatlands.
Environmental Sciences & Ecology↗
Proposed synthesis of a linear poly-ethylenimine with hydroxyl pendants substituents at the adjacent carbon
The synthesis of a linear poly-ethylenimine with pendant hydroxyl groups bonded to backbone carbons adjacent to the backbone amine groups is investigated and compared to the conventional method of functionalizing branched poly-ethylenimine using epoxides for use in direct air capture of carbon dioxide. The addition of hydroxyl groups imparts stability against both oxidative degradation and the formation of urea by reducing the number of primary amines, while the novel method of bonding to the adjacent backbone carbon rather than directly to the amine is hypothesized to retain the higher capacity for carbon dioxide of secondary amines when compared to tertiary amines. We also expect that the hydroxyl substituents will impart stronger hydrogen bonding capabilities, resulting in stronger interactions between adjacent polymer chains and a subsequent decrease in mobility.
36 MATERIALS SCIENCE↗
Motor Qualification for Long-Duration Mars Missions
Qualification of motors for deep space under extreme thermal environments to be encountered during the Mars Science Laboratory (MSL) mission is required to verify the reliability and validate mission assurance requirements. The motor assembly must survive all ground operations, plus the nominal 670 Martian-day (or sol) mission that includes summer and winter seasons of the Mars environment. The motor assembly was tested and characterized under extreme temperature conditions with reference to hardware requirements. The motor assembly has been proved to be remarkably robust and displayed no sign of degradation due to the 3 X (three times per JPL design principles) thermal environmental exposure to the punishing Mars surface operations cycles. The motor characteristics obtained before, during, and post-test comparisons for the surface operations cycles are within measurement error of one another. The motors withstood/survived 2,010 extreme temperature cycles with a Delta T of 190 C deep temperature cycles, representing three times the expected thermal cycling exposure during the MSL surface operations. The qualification test hardware elements (A200 motor assembly, encoders, and resolver) have not shown any signs of degradation due to the PQV (Package Qualification and Verification) testing. The test hardware has demonstrated sufficient life to survive the deep thermal cycles associated with MSL mission surface operations for three lives.
Ramesham, Rajeshuni↗
Chloroplast Stress Signals: Control of Retrograde Signaling, Chloroplast Turn-Over, and Cell Fate Decisions
Chloroplasts (photosynthetic plastids) are semiautonomous organelles that contain their own small genomes. The proteomes of chloroplasts, however, are a mixture of plastid and nuclear-encoded proteins. Chloroplasts perform photosynthesis, which is prone to damaging the organelles, leading to the production of reactive oxygen species (ROS) that damage the cell under environmental stresses. Thus, for the cell to maintain proper chloroplast function, efficient photosynthesis, and avoid ROS damage, it relies on complex crosstalk between the chloroplast, the nucleus, other organelles within the cell, and the cytoplasm in between. This communication involves retrograde signals from chloroplasts to control nuclear gene expression, programmed cell death (PCD), and chloroplast degradation. Here we review these signals with an emphasis on the roles of the ROS singlet oxygen ( 1 O 2 ) and plastid gene expression. We cover (1) recent work on understanding how multiple 1 O 2 signaling pathways can be initiated within stressed chloroplasts, (2) how individualized post-translational regulatory systems allow chloroplasts to control their proteomes and degradation, and (3) how chloroplast signals ultimately control cell fate decisions, such as PCD, senescence, and vacuole-mediated degradation of chloroplasts (chloroplast quality control). Overall, this chapter discusses how chloroplasts can act as environmental sensors for the cell and allow plants to acclimate to stress and thrive in dynamic environments.
59 BASIC BIOLOGICAL SCIENCES↗
Plasma Sprayed Bondable Stainless Surface (BOSS) Coatings for Corrosion Protection and Adhesion Treatments
Plasma-sprayed Bondable Stainless Surface (BOSS) coatings are being developed under the Solid Propulsion Integrity Program's (SPIP) Bondlines Package. These coatings are designed as a steel case preparation treatment prior to insulation lay-up. Other uses include the exterior of steel cases and bonding surfaces of nozzle components. They provide excellent bondability - rubber insulation and epoxy bonds fail cohesively within the polymer - for both fresh surfaces and surfaces having undergone natural and accelerated environmental aging. They have passed the MSFC requirements for protection of inland and sea coast environment. Because BOSS coatings are inherently corrosion resistant, they do not require preservation by greases or oils. The reduction/elimination of greases and oils, known bondline degraders, can increase SRM reliability, decrease costs by reducing the number of process steps, and decrease environmental pollution by reducing the amount of methyl chloroform used for degreasing and thus reduce release of the ozone-depleting chemical in accordance with the Clean Air Act and the Montreal Protocol. The coatings can potential extend the life of RSRM case segments and nozzle components by eliminating erosion due to multiple grit blasting during each use cycle and corrosion damage during marine recovery. Concurrent work for the Air Force show that other BOSS coatings give excellent bondline strength and durability for high-performance structures of aluminum and titanium.
Davis, G. D.↗
Reconfiguration of Analog Electronics for Extreme Environments: Problem or Solution?
This paper argues in favor of adaptive reconfiguration as a technique to expand the operational envelope of analog electronics for extreme environments (EE). In addition to hardening-by-process and hardening-by-design, "hardening-by-reconfiguration", when applicable, could be used to mitigate drifts, degradation, or damage on electronic devices (chips) in EE, by using re-configurable devices and an adaptive self-reconfiguration of their circuit topology. Conventional circuit design exploits device characteristics within a certain temperature/radiation range; when that is exceeded, the circuit function degrades. On a reconfigurable device, although component parameters change in EE, as long as devices still operate, albeit degraded, a new circuit design, suitable for new parameter values, may be mapped into the reconfigurable structure to recover the initial circuit function. Partly degraded resources are still used, while completely damaged resources are bypassed. Designs suitable for various environmental conditions can be determined prior to operation or can be determined in-situ, by adaptive reconfiguration algorithms running on built-in digital controllers. Laboratory demonstrations of this technique were performed by JPL in several independent experiments in which bulk CMOS reconfigurable devices were exposed to, and degraded by, low temperatures (approx. 196 C), high temperatures (approx.300 C) or radiation (300kRad TID), and then recovered by adaptive reconfiguration using evolutionary search algorithms. Taking this technology from Technology Readiness Level (TRL) 3 to TRL 5 is the target of a current NASA project.
Field Programmable Transistor Array (FPTA)↗