163 research outputs found
Research sensors
The program described covers development of sensors and sensing techniques for research applications on aeropropulsion systems. In general, the sensors are used in-situ to measure the environment at a given location within a turbine engine, or to measure the response of an engine component to the imposed environment. Locations of concern are generally in the gas path and, for the most part, are within the hot section. Specific parameters of concern are dynamic gas temperature, heat flux, airfoil surface temperature, and strain on airfoils and combustor liners. In order to minimize the intrusiveness of surface-mounted sensors, a considerable effort was expended to develop thin-film sensors for surface temperature, strain, and heat flux measurements. Most of the work described is sufficiently advanced that sensors were used and useful data were obtained. The notable exception is the work to develop a high-temperature static strain measuring capability; this work is still in progress
Progress on a PdCr wire strain gage
The principal activity under the HOST effort to improve the state of the art in high temperature static strain measurement has been a contract under which a palladium-chromium (PdCr) alloy was developed. The contract effort is continuing with the goal of developing a thin film high temperature static strain gage system. In addition to this effort, researchers contracted with Battelle-Columbus Laboratories to draw the PdCr allow into wire while researchers at Lewis worked to gain experience with this alloy as a wire strain gage
Research sensors
The LeRC program in research sensors is directed at development of sensors and sensing techniques for research applications on turbine engines and propulsion systems. In general, the sensors are used either to measure to response of an engine component to the imposed environment. Locations of concern are generally within the gas path and, for the most part, are within the hot section of the engine. Since these sensors are used for research testing as opposed to operational use, a sensor lifetime of the order of 50 hr is considered sufficient. The following discussion presents a sample of this work, describing programs to develop a dynamic gas temperature measuring system, total heat flux sensors, a variety of thin-film sensors, and high-temperature strain measuring systems
Research sensors
The work described is part of a program (Englund and Seasholtz, 1988) to develop sensors and sensing techniques for research applications on aircraft turbine engines. In general, the sensors are used to measure the environment at a given location within a turbine engine or to measure the response of an engine component to the imposed environment. Locations of concern are generally in the gas path and, for the most part, are within the hot section. Specific parameters of concern are dynamic gas temperature, heat flux, airfoil surface temperature, and strain on airfoils and combustor liners. To minimize the intrusiveness of surface-mounted sensors, a considerable effort was expended to develop thin-film sensors for surface temperature, strain, and heat flux measurements. In addition, an optical system for viewing the interior of an operating combustor was developed. Most of the work described is sufficiently advanced that the sensors were used and useful data were obtained. The notable exception is the work to develop a high-temperature static strain measuring capability; the work is still in progress
Recent advances in high temperature instrumentation for hot section applications
Programs to develop research instrumentation for use in turbine engine hot sections are described. These programs were initiated to provide improved measurements capability as support for a multidisciplinary effort to establish technolgy leading to improved hot section durability. Specific measurement systems described here include heat flux sensors, a dynamic gas temperature measuring system, laser anemometry for hot section applications, an optical system for viewing the interior of a combustor during operation, thin film sensors for surface temperature and strain measurements, and high temperature strain measuring systems. The paper describes the state of the development of these sensors and measuring systems and, in some cases, will show examples of measurements made with this instrumentation.The paper covers work done at the NASA Lewis Research Center and at various contract and grant facilities
High-speed photonic crystal modulator with non-volatile memory via structurally-engineered strain concentration in a piezo-MEMS platform
Numerous applications in quantum and classical optics require scalable,
high-speed modulators that cover visible-NIR wavelengths with low footprint,
drive voltage (V) and power dissipation. A critical figure of merit for
electro-optic (EO) modulators is the transmission change per voltage, dT/dV.
Conventional approaches in wave-guided modulators seek to maximize dT/dV by the
selection of a high EO coefficient or a longer light-material interaction, but
are ultimately limited by nonlinear material properties and material losses,
respectively. Optical and RF resonances can improve dT/dV, but introduce added
challenges in terms of speed and spectral tuning, especially for high-Q
photonic cavity resonances. Here, we introduce a cavity-based EO modulator to
solve both trade-offs in a piezo-strained photonic crystal cavity. Our approach
concentrates the displacement of a piezo-electric actuator of length L and a
given piezoelectric coefficient into the PhCC, resulting in dT/dV proportional
to L under fixed material loss. Secondly, we employ a material deformation that
is programmable under a "read-write" protocol with a continuous, repeatable
tuning range of 5 GHz and a maximum non-volatile excursion of 8 GHz. In
telecom-band demonstrations, we measure a fundamental mode linewidth = 5.4 GHz,
with voltage response 177 MHz/V corresponding to 40 GHz for voltage spanning
-120 to 120 V, 3dB-modulation bandwidth of 3.2 MHz broadband DC-AC, and 142 MHz
for resonant operation near 2.8 GHz operation, optical extinction down to
min(log(T)) = -25 dB via Michelson-type interference, and an energy consumption
down to 0.17 nW/GHz. The strain-enhancement methods presented here are
applicable to study and control other strain-sensitive systems
Next Generation Metallic Iron Nodule Technology in Electric Arc Steelmaking - Phase II
The current trend in the steel industry is a gradual decline in conventional steelmaking from taconite pellets in blast furnaces, and an increasing number of alternative processes using metallic scrap iron, pig iron and metallized iron ore products. Currently, iron ores from Minnesota and Michigan are pelletized and shipped to the lower Great Lakes ports as blast furnace feed. The existing transportation system and infrastructure is geared to handling these bulk materials. In order to expand the opportunities for the existing iron ore mines beyond their blast furnace customer base, a new material is needed to satisfy the needs of the emerging steel industry while utilizing the existing infrastructure and materials handling. A recent commercial installation employing Kobe Steel’s ITmk3 process, was installed in Northeastern Minnesota. The basic process uses a moving hearth furnace to directly reduce iron oxides to metallic iron from a mixture of iron ore, coals and additives. The resulting products can be shipped using the existing infrastructure for use in various steelmaking processes. The technology reportedly saves energy by 30% over the current integrated steelmaking process and reduces emissions by more than 40%. A similar large-scale pilot plant campaign is also currently in progress using JFE Steel’s Hi-QIP process in Japan. The objective of this proposal is to build upon and improve the technology demonstrated by Kobe Steel and JFE, by further reducing cost, improving quality and creating added incentive for commercial development. This project expands previous research conducted at the University of Minnesota Duluth’s Natural Resources Research Institute and that reported by Kobe and JFE Steel. Three major issues have been identified and are addressed in this project for producing high-quality nodular reduced iron (NRI) at low cost: (1) reduce the processing temperature, (2) control the furnace gas atmosphere over the NRI, and (3) effectively use sub-bituminous coal as a reductant. From over 4000 laboratory tube and box furnace tests, it was established that the correct combination of additives, fluxes, and reductant while controlling the concentration of CO and CO2 in the furnace atmosphere (a) lowers the operating temperature, (b) decreases the use of reductant coal (c) generates less micro nodules of iron, and (d) promotes desulphurization. The laboratory scale work was subsequently verified on 12.2 m (40 ft) long pilot scale furnace. High quality NRI could be produced on a routine basis using the pilot furnace facility with energy provided from oxy-gas or oxy-coal burner technologies. Specific strategies were developed to allow the use of sub-bituminous coals both as a hearth material and as part of the reaction mixture. Computational Fluid Dynamics (CFD) modeling was used to study the overall carbothermic reduction and smelting process. The movement of the furnace gas on a pilot hearth furnace and larger simulated furnaces and various means of controlling the gas atmosphere were evaluated. Various atmosphere control methods were identified and tested during the course of the investigation. Based on the results, the appropriate modifications to the furnace were made and tested at the pilot scale. A series of reduction and smelting tests were conducted to verify the utility of the processing conditions. During this phase, the overall energy use characteristics, raw materials, alternative fuels, and the overall economics predicted for full scale implementation were analyzed. The results indicate that it should be possible to lower reaction temperatures while simultaneously producing low sulfur, high carbon NRI if the right mix chemistry and atmosphere are employed. Recommendations for moving the technology to the next stage of commercialization are presented
Evidence for distinct coastal and offshore communities of bottlenose dolphins in the north east Atlantic.
Bottlenose dolphin stock structure in the northeast Atlantic remains poorly understood. However, fine scale photo-id data have shown that populations can comprise multiple overlapping social communities. These social communities form structural elements of bottlenose dolphin (Tursiops truncatus) [corrected] populations, reflecting specific ecological and behavioural adaptations to local habitats. We investigated the social structure of bottlenose dolphins in the waters of northwest Ireland and present evidence for distinct inshore and offshore social communities. Individuals of the inshore community had a coastal distribution restricted to waters within 3 km from shore. These animals exhibited a cohesive, fission-fusion social organisation, with repeated resightings within the research area, within a larger coastal home range. The offshore community comprised one or more distinct groups, found significantly further offshore (>4 km) than the inshore animals. In addition, dorsal fin scarring patterns differed significantly between inshore and offshore communities with individuals of the offshore community having more distinctly marked dorsal fins. Specifically, almost half of the individuals in the offshore community (48%) had characteristic stereotyped damage to the tip of the dorsal fin, rarely recorded in the inshore community (7%). We propose that this characteristic is likely due to interactions with pelagic fisheries. Social segregation and scarring differences found here indicate that the distinct communities are likely to be spatially and behaviourally segregated. Together with recent genetic evidence of distinct offshore and coastal population structures, this provides evidence for bottlenose dolphin inshore/offshore community differentiation in the northeast Atlantic. We recommend that social communities should be considered as fundamental units for the management and conservation of bottlenose dolphins and their habitat specialisations
Atmospheric Methane : Comparison Between Methane's Record in 2006–2022 and During Glacial Terminations
Atmospheric methane's rapid growth from late 2006 is unprecedented in the observational record. Assessment of atmospheric methane data attributes a large fraction of this atmospheric growth to increased natural emissions over the tropics, which appear to be responding to changes in anthropogenic climate forcing. Isotopically lighter measurements of (Figure presented.) are consistent with the recent atmospheric methane growth being mainly driven by an increase in emissions from microbial sources, particularly wetlands. The global methane budget is currently in disequilibrium and new inputs are as yet poorly quantified. Although microbial emissions from agriculture and waste sources have increased between 2006 and 2022 by perhaps 35 Tg/yr, with wide uncertainty, approximately another 35–45 Tg/yr of the recent net growth in methane emissions may have been driven by natural biogenic processes, especially wetland feedbacks to climate change. A model comparison shows that recent changes may be comparable or greater in scale and speed than methane's growth and isotopic shift during past glacial/interglacial termination events. It remains possible that methane's current growth is within the range of Holocene variability, but it is also possible that methane's recent growth and isotopic shift may indicate a large-scale reorganization of the natural climate and biosphere is under way
Atmospheric Methane: Comparison Between Methane's Record in 2006–2022 and During Glacial Terminations
Atmospheric methane's rapid growth from late 2006 is unprecedented in the observational record.
Assessment of atmospheric methane data attributes a large fraction of this atmospheric growth to increased natural emissions over the tropics, which appear to be responding to changes in anthropogenic climate forcing.
Isotopically lighter measurements of d13C-CH4 are consistent with the recent atmospheric methane growth being mainly driven by an increase in emissions from microbial sources, particularly wetlands. The global methane budget is currently in disequilibrium and new inputs are as yet poorly quantified. Although microbial emissions from agriculture and waste sources have increased between 2006 and 2022 by perhaps 35 Tg/yr, with wide uncertainty, approximately another 35–45 Tg/yr of the recent net growth in methane emissions may have been driven by natural biogenic processes, especially wetland feedbacks to climate change. A model comparison shows that recent changes may be comparable or greater in scale and speed than methane's growth and isotopic shift during past glacial/interglacial termination events. It remains possible that methane's current growth is within the range of Holocene variability, but it is also possible that methane's recent growth and isotopic shift may indicate a large-scale reorganization of the natural climate and biosphere is under way
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