Fuel Flexible Combustor for High-OPR Compact-Core N+3 Propulsion Engine

This document reports unlimited-rights data relating to technical work under NASA contract NNC14CA30C, performed throughout the full period of the effort. This period comprises Fiscal Years 2015 through 2019 (inclusive); this period includes the 4th Quarter of Calendar Year 2014, all of Calendar Years 2015 through 2018, and the first three Quarters of Calendar Year 2019. Limited-rights data relating to technical progress during this period are provided in a separate document, a Limited Rights version of this report having limited rights markings

Emission Characteristics of an Axially Staged Sector Combustor for a Small Core High OPR Subsonic Aircraft Engine

This paper presents the nitrogen oxides, carbon monoxide, and particulate matter emissions of a single sector axially staged combustor sector designed and fabricated by United Technologies Research Center (UTRC) in partnership with NASA under a compact low-emissions combustor contract supported by the NASA Advanced Air Transport Technology (AATT) N+3 project. The test was conducted at NASA Glenn Research Center's CE-5 combustion test facility. The facility provided inlet air temperatures up to 922 K and pressures up to 19.0 bar. The combustor design concept, called Axially Controlled Stoichiometry (ACS), was developed by Pratt & Whitney (P&W) under NASA's Environmentally Responsible Aviation (ERA) program for an N+2 combustor for use in twin-aisle subsonic aircraft engines. Under the N+3 project the ACS combustor was scaled-down for application to small-core N+3 engines for use in single-aisle aircraft. The results show that the NOx and CO emissions characteristics are similar in both the N+2 and N+3 applications. The non-volatile particulate matter (nvPM) emissions trends are similar to CO emissions with an exception at high fuel-air ratio, as inlet air temperature and pressure conditions change from taxi to approach. Three NOx correlation equations are generated to describe theNOx emissions of this combustor. The percentage landing and takeoff (LTO) NOx reduction of the N+3 ACS combustor is between 82% and 89% relative to the ICAO CAEP/6 standard, which meets the NASA N+3 goal of exceeding 80% LTO NOx reduction

Grizzly Bear Use of Forest Service Grazing Allotments in The Greater Yellowstone Ecosystem (Poster)

Range expansion of the Greater Yellowstone Ecosystem (GYE) grizzly bear (Ursus arctos) population has led to increased human-bear conflicts, including livestock depredation. In 2015, we began a study to evaluate spatio-temporal patterns between public land livestock grazing, grizzly bear habitat use and livestock depredations. In collaboration with the U.S. Forest Service and the Interagency Grizzly Bear Study Team, we will obtain 25 years (1989-2014) of data related to Forest Service grazing allotments, including livestock stocking and on-off dates, locations of individual collared bears, grizzly bear depredations and management removals, bear density and habitat characteristics pertinent to bear space use (e.g. landcover, elevation, human activity) within the GYE. Bear and conflict locations will be related to allotment information, habitat characteristics, and bear density using generalized linear models to evaluate what factors are influencing grizzly bear space use and depredation events, and how they have changed across seasons and years. Habitat selection by individual bears will be evaluated at two scales, home range selection within the landscape and selection within the home range, to give more insight into factors affecting space use and how they differ among individual bears. Our results should facilitate the development of adaptive approaches to conserve grizzly bears while also conserving the economic viability of livestock operations, and should have utility for bear and land management in the GYE

Catalytic Combustion of Gasified Coal for Low-Emissions Gas Turbines

In response to the Department of Energy’s (DOE) goals of developing low emission, coal-based power systems, Precision Combustion, Inc. is developing a low, single digit ppm NOx emissions system for high firing temperature IGCC systems. The present paper presents emissions data for syngas and alternate fuels tested successfully. Subscale testing results at 10 atmospheres include NOx emissions meeting DOE\u27s target of 0.01 lbs/MMBtu (3 ppm at 15% O2) and were below this value under some operating conditions during parametric testing

Resource Adequacy: Should Regulators Worry?

Regulators have proposed various institutional alternatives to secure network resource adequacy and reasonably priced electric power for consumers. These alternatives prompt many difficult questions: Does the development of Demand Response reduce the need for new capacity? How effectively can a government-mandated Capacity Market foster efficient investment? How does centralized generator commitment (with revenue guarantees) compare to a system in which Generators voluntarily commit themselves with no revenue guarantees? If exclusive distribution contracts were replaced by unregulated retail competition, what would be the effects on investment and market prices? We use laboratory experiments to address these questions

Evolutionary history of mammalian sucking lice (Phthiraptera: Anoplura)

<p>Abstract</p> <p>Background</p> <p>Sucking lice (Phthiraptera: Anoplura) are obligate, permanent ectoparasites of eutherian mammals, parasitizing members of 12 of the 29 recognized mammalian orders and approximately 20% of all mammalian species. These host specific, blood-sucking insects are morphologically adapted for life on mammals: they are wingless, dorso-ventrally flattened, possess tibio-tarsal claws for clinging to host hair, and have piercing mouthparts for feeding. Although there are more than 540 described species of Anoplura and despite the potential economical and medical implications of sucking louse infestations, this study represents the first attempt to examine higher-level anopluran relationships using molecular data. In this study, we use molecular data to reconstruct the evolutionary history of 65 sucking louse taxa with phylogenetic analyses and compare the results to findings based on morphological data. We also estimate divergence times among anopluran taxa and compare our results to host (mammal) relationships.</p> <p>Results</p> <p>This study represents the first phylogenetic hypothesis of sucking louse relationships using molecular data and we find significant conflict between phylogenies constructed using molecular and morphological data. We also find that multiple families and genera of sucking lice are not monophyletic and that extensive taxonomic revision will be necessary for this group. Based on our divergence dating analyses, sucking lice diversified in the late Cretaceous, approximately 77 Ma, and soon after the Cretaceous-Paleogene boundary (ca. 65 Ma) these lice proliferated rapidly to parasitize multiple mammalian orders and families.</p> <p>Conclusions</p> <p>The diversification time of sucking lice approximately 77 Ma is in agreement with mammalian evolutionary history: all modern mammal orders are hypothesized to have diverged by 75 Ma thus providing suitable habitat for the colonization and radiation of sucking lice. Despite the concordant timing of diversification events early in the association between anoplurans and mammals, there is substantial conflict between the host and parasite phylogenies. This conflict is likely the result of a complex history of host switching and extinction events that occurred throughout the evolutionary association between sucking lice and their mammalian hosts. It is unlikely that there are any ectoparasite groups (including lice) that tracked the early and rapid radiation of eutherian mammals.</p

Livestock Depredation by Grizzly Bears on Forest Service Grazing Allotments in the Greater Yellowstone Ecosystem

Grizzly bear population growth and range expansion over the last several decades in the Greater Yellowstone Ecosystem (GYE) has led to increased human-bear conflicts, including livestock depredation. In 2015, we began a study to evaluate spatio-temporal relationships between livestock grazing, grizzly bear habitat characteristics, and livestock depredations by grizzly bears on public lands in the GYE during 1992–2014. In collaboration with the U.S. Forest Service (USFS), Interagency Grizzly Bear Study Team, and National Park Service, we have obtained 23 years of grazing allotment attributes for 316 USFS and Grand Teton National Park grazing allotments including: livestock stocking information, grizzly bear habitat characteristics, grizzly bear density and distribution, and livestock depredation counts. Overall counts of livestock depredation events, total livestock killed, and the number of allotments experiencing depredations increased from 1992 to 2014, concurrent with range expansion and increasing grizzly bear densities. Annual depredation events per allotment differed by livestock class, where allotments stocked with cow-calf pairs and sheep experienced the majority of depredations. Livestock depredation counts will be modeled with livestock stocking data and grizzly bear habitat variables to better understand which attributes of grazing allotments had the greatest association with the number of depredations over the study period. We will evaluate habitat attributes at two spatial scales, representing daily and annual grizzly bear activity areas. Our results will enhance adaptive approaches to conserve grizzly bears, while also maintaining the economic viability of livestock operations

Mixer Assembly for a Gas Turbine Engine

A mixer assembly for a gas turbine engine is provided, including a main mixer with fuel injection holes located between at least one radial swirler and at least one axial swirler, wherein the fuel injected into the main mixer is atomized and dispersed by the air flowing through the radial swirler and the axial swirler

Thermoelectric refrigerator

A refrigerator is provided which combines the benefits of superinsulation materials with thermoelectric devices and phase change materials to provide an environmentally benign system that is energy efficient and can maintain relatively uniform temperatures for extended periods of time with relatively low electrical power requirements. The refrigerator includes a thermoelectric assembly having a thermoelectric device with a hot sink and a cold sink. The superinsulation materials include a plurality of vacuum panels. The refrigerator is formed from an enclosed structure having a door. The vacuum panels may be contained within the walls of the enclosed structure and the door. By mounting the thermoelectric assembly on the door, the manufacturer of the enclosed structure is simplified and the overall R rating of the refrigerator increased. Also an electrical motor and propellers may be mounted on the door to assist in the circulation of air to improve the efficiency of the cold sink and the hot sink. A propeller and/or impeller is preferably mounted within the refrigerator to assist in establishing the desired air circulation flow path

Climatic controls of aboveground net primary production in semi‑arid grasslands along a latitudinal gradient portend low sensitivity to warming

Although climate models forecast warmer temperatures with a high degree of certainty, precipitation is the primary driver of aboveground net primary production (ANPP) in most grasslands. Conversely, variations in temperature seldom are related to patterns of ANPP. Thus forecasting responses to warming is a challenge, and raises the question: how sensitive will grassland ANPP be to warming? We evaluated climate and multi-year ANPP data (67 years) from eight western US grasslands arrayed along mean annual temperature (MAT; ~7–14 °C) and mean annual precipitation (MAP; ~250–500 mm) gradients. We used regression and analysis of covariance to assess relationships between ANPP and temperature, as well as precipitation (annual and growing season) to evaluate temperature sensitivity of ANPP. We also related ANPP to the standardized precipitation evaporation index (SPEI), which combines precipitation and evapotranspiration to better represent moisture available for plant growth. Regression models indicated that variation in growing season temperature was negatively related to total and graminoid ANPP, but precipitation was a stronger predictor than temperature. Growing season temperature was also a significant parameter in more complex models, but again precipitation was consistently a stronger predictor of ANPP. Surprisingly, neither annual nor growing season SPEI were as strongly related to ANPP as precipitation. We conclude that forecasted warming likely will affect ANPP in these grasslands, but that predicting temperature effects from natural climatic gradients is difficult. This is because, unlike precipitation, warming effects can be positive or negative and moderated by shifts in the C3/C4 ratios of plant communities