Experimental clean combustor program; noise measurement addendum, Phase 2

Combustor noise measurements were performed using wave guide probes. Test results from two full scale annular combustor configurations in a combustor test rig are presented. A CF6-50 combustor represented a current design, and a double annular combustor represented the advanced clean combustor configuration. The overall acoustic power levels were found to correlate with the steady state heat release rate and inlet temperature. A theoretical analysis for the attenuation of combustor noise propagating through a turbine was extended from a subsonic relative flow condition to include the case of supersonic flow at the discharge side. The predicted attenuation from this analysis was compared to both engine data and extrapolated component combustor data. The attenuation of combustor noise through the CF6-50 turbine was found to be greater than 14 dB by both the analysis and the data

Experimental clean combustor program noise measurement addendum, phase 1

The test results of combustor noise measurements taken with waveguide probes are presented. Waveguide probes were shown to be a viable measurement technique for determining high sound pressure level broadband noise. A total of six full-scale annular combustors were tested and included the three advanced combustor designs: swirl-can, radial/axial, and double annular

Perpetual Cancellable American Call Option

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93569/1/j.1467-9965.2011.00479.x.pd

Bearing the Cost of Stored Carbon Leakage

Carbon capture and sequestration (CCS) is considered a key technology for stabilizing climate change. However, leakage of CO2 from stored carbon can potentially undermine the value of carbon storage as a mitigation option. Thus, monitoring and verifiability of CO2 storage should be encouraged through policy provisions such as accounting and pricing of leaked emissions. Here we assess different institutional and economic mechanisms for accounting for carbon leakage. Using an integrated assessment model we quantify the impacts on the climate, the economy and the mitigation strategies. Results show that carbon leakage can reduce the share of fossil based CCS by up to 35%, if it is controlled and correctly priced. Biomass based CCS is less affected. Accounting for leakage leads to an increase of climate policy costs of up to 0.4 percentage points due to increased emissions

The Charging Structure for the Great Barrier Reef - A review of willingness to pay

The Great Barrier Reef Marine Park Authority (GBRMPA or the Reef Authority) is currently conducting a comprehensive review of the charging structure for the use of the Great Barrier Reef (GBR) Marine Park with a view to implement potential changes from 1 July 2023

Exotic magnetism in the alkali sesquoxides Rb4O6 and Cs4O6

Among the various alkali oxides the sesquioxides Rb4O6 and Cs4O6 are of special interest. Electronic structure calculations using the local spin-density approximation predicted that Rb4O6 should be a half-metallic ferromagnet, which was later contradicted when an experimental investigation of the temperature dependent magnetization of Rb4O6 showed a low-temperature magnetic transition and differences between zero-field-cooled (ZFC) and field-cooled (FC) measurements. Such behavior is known from spin glasses and frustrated systems. Rb4O6 and Cs4O6 comprise two different types of dioxygen anions, the hyperoxide and the peroxide anions. The nonmagnetic peroxide anions do not contain unpaired electrons while the hyperoxide anions contain unpaired electrons in antibonding pi*-orbitals. High electron localization (narrow bands) suggests that electronic correlations are of major importance in these open shell p-electron systems. Correlations and charge ordering due to the mixed valency render p-electron-based anionogenic magnetic order possible in the sesquioxides. In this work we present an experimental comparison of Rb4O6 and the related Cs4O6. The crystal structures are verified using powder x-ray diffraction. The mixed valency of both compounds is confirmed using Raman spectroscopy, and time-dependent magnetization experiments indicate that both compounds show magnetic frustration, a feature only previously known from d- and f-electron systems

Ballistic Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development

An experimental program is underway to develop a consistent set of material property and impact test data, and failure analysis, for a variety of materials that can be used to develop improved impact failure and deformation models. Unique features of this set of data are that all material property information and impact test results are obtained using identical materials, the test methods and procedures are extensively documented and all of the raw data is available. This report describes ballistic impact testing which has been conducted on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade

Kohlenstoffsequestrierung beim Anbau alternativer Energiepflanzen

Die landwirtschaftliche Biomasseproduktion zur energetischen Nutzung hat in den letzten Jahren deutlich an Bedeutung gewonnen. Neben Mais als dem dominierenden Substrat werden vermehrt alternative, mehrjährige Energiepflanzen wie die Durchwachsene Silphie oder Szarvasigras angebaut. Einige Studien bspw. mit Miscanthus haben bereits gezeigt, dass der Anbau von mehrjährigen Energiepflanzen zu einem Anstieg der organischen Bodensubstanz führen kann. Ziel der Arbeit war es, verschiedene Energiepflanzen bezüglich deren Einflusses auf Gesamtkohlenstoffgehalte und partikulären Fraktionen (fPOM, oPOM), sowie deren mikrobielle Parameter und Enzymaktivitäten zu bewerten und vergleichen. Wir konnten zeigen, dass sich die Gehalte an organischer Bodensubstanz, verglichen mit Mais, unter den mehrjährigen Energiepflanzen positiv entwickelt haben. Insbesondere der Anteil an stabilen Kohlenstofffraktionen nahm zu. Weiterhin waren die Bestände alternativer Energiepflanzen verglichen mit Mais durch höhere mikrobielle Aktivität und Enzymaktivitäten gekennzeichnet

High-temperature and low-temperature supercritical drying of aerogels – structural investigations with SAXS

Base-catalyzed silica aerogels are composed of particles with a mean size of about 5 nm, which form a chain-like porous network. Up to now it has been assumed that supercritical drying (SCD) of highly porous gels in autoclaves leaves the structure nearly unchanged. Small-angle X-ray scattering (SAXS) measurements provide evidence that this is only true for the low-temperature CO$_2$ drying process with a critical temperature Tc = 304.2 K and a critical pressure pc = 73.9 × 10$^5$ Pa. In the high-temperature methanol process (Tc = 512.5 K and pc = 80.9 × 10$^5$ Pa) with remaining water and catalyst, however, structural changes are introduced. The SAXS measurements can be explained by a narrowing of the particle-size distribution during the heating period of the autoclave process. In a double-logarithmic representation of the scattered intensity I versus the scattering vector q, intermediate slopes smaller than -4 in the Porod region as well as oscillations in an Iq$_4$ vs q plot appear. On the contrary, SCD hardly affects the particle structure of acid-catalyzed gels and, if the basic solvent is exchanged for pure methanol, of base-catalyzed gels