Calibration Procedure for Fuel Flow Meters at the Nebraska Tractor Test Lab

Reports in the literature indicated several factors that can influence the accuracy of Coriolis Effect mass flow meters. A Coriolis Effect mass flow meter is used to verify tractor manufacturer’s fuel consumption claims at the Nebraska Tractor Test Laboratory (NTTL). The accuracy requirement placed on the flow meter by the Organization for Economic Co-operation and Development (OECD) in the Code 2 tractor performance test procedure is not clear, but in the most conservative interpretation is ±0.5% of each flow rate measured. Results showed a dynamic weighing calibration method was not accurate enough to obtain a calibration of the flow meter to the desired accuracy level. A static weighing calibration method developed showed no significant difference between the calibration determined by the flow meter’s manufacturer with water and the calibration determined by NTTL with No. 2 diesel fuel. Static weighing calibration tests showed that for flow rates at or above 32 kg/h, the flow meter met the ±0.5% error most conservative interpretation of tolerance on flow rate from OECD Code 2

VLASS tidal disruption events with optical flares I: the sample and a comparison to optically-selected TDEs

In this work, we use the Jansky VLA Sky Survey (VLASS) to compile the first sample of six radio-selected tidal disruption events (TDEs) with transient optical counterparts. While we still lack the statistics to do detailed population studies of radio-selected TDEs, we use these events to suggest trends in host galaxy and optical light curve properties that may correlate with the presence of radio emission, and hence can inform optically-selected TDE radio follow-up campaigns. We find that radio-selected TDEs tend to have faint and cool optical flares, as well as host galaxies with low SMBH masses. Our radio-selected TDEs also tend to have more energetic, larger radio emitting regions than radio-detected, optically-selected TDEs. We consider possible explanations for these trends, including by invoking super-Eddington accretion and enhanced circumnuclear media. Finally, we constrain the radio-emitting TDE rate to be $\gtrsim 10$ Gpc$^{-3}$ yr$^{-1}$.Comment: 26 pages, 5 tables, 11 figures, submitted to Ap

Seasonal dynamics of active SAR11 ecotypes in the oligotrophic Northwest Mediterranean Sea

A seven-year oceanographic time series in NW Mediterranean surface waters was combined with pyrosequencing of ribosomal RNA (16S rRNA) and ribosomal RNA gene copies (16S rDNA) to examine the environmental controls on SAR11 ecotype dynamics and potential activity. SAR11 diversity exhibited pronounced seasonal cycles remarkably similar to total bacterial diversity. The timing of diversity maxima was similar across narrow and broad phylogenetic clades and strongly associated with deep winter mixing. Diversity minima were associated with periods of stratification that were low in nutrients and phytoplankton biomass and characterised by intense phosphate limitation (turnover time80%) by SAR11 Ia. A partial least squares (PLS) regression model was developed that could reliably predict sequence abundances of SAR11 ecotypes (Q2=0.70) from measured environmental variables, of which mixed layer depth was quantitatively the most important. Comparison of clade-level SAR11 rRNA:rDNA signals with leucine incorporation enabled us to partially validate the use of these ratios as an in-situ activity measure. However, temporal trends in the activity of SAR11 ecotypes and their relationship to environmental variables were unclear. The strong and predictable temporal patterns observed in SAR11 sequence abundance was not linked to metabolic activity of different ecotypes at the phylogenetic and temporal resolution of our study

The Economics and Logistics of the Dual Harvest of Grain and Biomass in a Single-Pass

Significant interest has developed in using cellulosic resources, especially crop residues, to create biofuels. Collecting these residues in a single-pass of the harvester across the field has the potential to be a low cost option. Two models have been developed; the first characterizes the in-field logistics of single-pass crop residue collection, the second the economics. These models allow the user to easily examine a wide variety of both grain-only and single-pass residue collection harvest cases. A variety of possible residue collection cases have been examined, and their effects both on harvester field capacity and harvest cost compared to grain-only harvest have been quantified. Systems where a harvester-towed wagon unloads collected residue directly at the field edge without any intermediary residue-hauling carts were generally the lowest cost. Cost-effective systems were shown to deliver crop residues to a biomass refinery at a mean cost of between $37 and$53 per metric dry matter ton depending on the acceptable reduction in harvester field capacity. Adviser: Michael F. Koche

Calibration Procedure for Fuel Flow Meters at the Nebraska Tractor Test Lab

Reports in the literature indicated several factors that can influence the accuracy of Coriolis Effect mass flow meters. A Coriolis Effect mass flow meter is used to verify tractor manufacturer’s fuel consumption claims at the Nebraska Tractor Test Laboratory (NTTL). The accuracy requirement placed on the flow meter by the Organization for Economic Co-operation and Development (OECD) in the Code 2 tractor performance test procedure is not clear, but in the most conservative interpretation is ±0.5% of each flow rate measured. Results showed a dynamic weighing calibration method was not accurate enough to obtain a calibration of the flow meter to the desired accuracy level. A static weighing calibration method developed showed no significant difference between the calibration determined by the flow meter’s manufacturer with water and the calibration determined by NTTL with No. 2 diesel fuel. Static weighing calibration tests showed that for flow rates at or above 32 kg/h, the flow meter met the ±0.5% error most conservative interpretation of tolerance on flow rate from OECD Code 2

Final Report for SERDP Project RC-1649: Advanced Chemical Measurements of Smoke from DoD-prescribed Burns

Objectives: Project RC-1649, “Advanced Chemical Measurement of Smoke from DoD-prescribed Burns” was undertaken to use advanced instrumental techniques to study in detail the particulate and vapor-phase chemical composition of the smoke that results from prescribed fires used as a land management tool on DoD bases, particularly bases in the southeastern U.S. The statement of need (SON) called for “(1) improving characterization of fuel consumption” and “(2) improving characterization of air emissions under both flaming and smoldering conditions with respect to volatile organic compounds, heavy metals, and reactive gases.” The measurements and fuels were from several bases throughout the southeast (Camp Lejeune, Ft. Benning, and Ft. Jackson) and were carried out in collaboration and conjunction with projects 1647 (models) and 1648 (particulates, SW bases). Technical Approach: We used an approach that featured developing techniques for measuring biomass burning emission species in both the laboratory and field and developing infrared (IR) spectroscopy in particular. Using IR spectroscopy and other methods, we developed emission factors (EF, g of effluent per kg of fuel burned) for dozens of chemical species for several common southeastern fuel types. The major measurement campaigns were laboratory studies at the Missoula Fire Sciences Laboratory (FSL) as well as field campaigns at Camp Lejeune, NC, Ft. Jackson, SC, and in conjunction with 1648 at Vandenberg AFB, and Ft. Huachuca. Comparisons and fusions of laboratory and field data were also carried out, using laboratory fuels from the same bases. Results: The project enabled new technologies and furthered basic science, mostly in the area of infrared spectroscopy, a broadband method well suited to biomass burn studies. Advances in hardware, software and supporting reference data realized a nearly 20x improvement in sensitivity and now provide quantitative IR spectra for potential detection of ~60 new species and actual field quantification of several new species such as nitrous acid, glycolaldehyde, α-/β-pinene and D-limonene. The new reference data also permit calculation of the global warming potential (GWP) of the greenhouse gases by enabling 1) detection of their ambient concentrations, and 2) quantifying their ability to absorb IR radiation