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CHARACTERIZATION OF THERMALLY DAMAGED LX-17

Description: Thermal damage was applied to LX-17 at 190 C for several hours. The damaged LX-17 samples, after cooled down to room temperature, were characterized for their material properties (density, porosity, permeability, moduli), safety, and performance. Weight losses upon thermal exposure were insignificant (< 0.1% wt.). The damaged LX-17 samples expanded, resulting in a bulk density reduction of 4.3%. Subsequent detonation measurements (cylinder tests) were conducted on the thermally-damaged LX-17 samples. The results showed that the fractions of damaged LX-17 reacted were slightly lower than those of pristine LX-17. The thermally damaged LX-17 had a detonation velocity of 7.315 mm/{micro}s, lower than that (7.638 mm/{micro}s) of pristine LX-17. Detonation energy density for the damaged LX-17 was 5.08 kJ/cm{sup 3}, about 9.0% lower than the detonation energy density of 5.50 kJ/cm{sup 3} for the pristine LX-17. The break-out curves showed reaction zone lengths for pristine LX-17 and damaged LX-17 were similar but the damaged samples had ragged detonation fronts.
Date: July 11, 2007
Creator: Hsu, P C
Partner: UNT Libraries Government Documents Department

Particle-Size-Distribution of Nevada Test Site Soils

Description: The amount of each size particle in a given soil is called the particle-size distribution (PSD), and the way it feels to the touch is called the soil texture. Sand, silt, and clay are the three particle sizes of mineral material found in soils. Sand is the largest sized particle and it feels gritty; silt is medium sized and it feels floury; and clay is the smallest and if feels sticky. Knowing the particle-size distribution of a soil sample helps to understand many soil properties such as how much water, heat, and nutrients the soil will hold, how fast water and heat will move through the soil, and what kind of structure, bulk density and consistence the soil will have. Furthermore, the native particle-size distribution of the soil in the vicinity of ground zero of a nuclear detonation plays a major role in nuclear fallout. For soils that have a high-sand content, the near-range fallout will be relatively high and the far-range fallout will be relatively light. Whereas, for soils that have a high-silt and high-clay content, the near-range fallout will be significantly lower and the far-range fallout will be significantly higher. As part of a program funded by the Defense Threat Reduction Agency (DTRA), the Lawrence Livermore National Laboratory (LLNL) has recently measured the PSDs from the various major areas at the Nevada Test Site where atmospheric detonations and/or nuclear weapon safety tests were performed back in the 50s and 60s. The purpose of this report is to document those results.
Date: September 17, 2007
Creator: Spriggs, G & Ray-Maitra, A
Partner: UNT Libraries Government Documents Department

Final Technical Report

Description: The two main objectives of this project were: 1) to develop and test technologies to harvest, transport, store, and separate corn stover to supply a clean raw material to the bioproducts industry, and 2) engineer fermentation systems to meet performance targets for lactic acid and ethanol manufacturers. Significant progress was made in testing methods to harvest corn stover in a “single pass” harvest mode (collect corn grain and stover at the same time). This is technically feasible on small scale, but additional equipment refinements will be needed to facilitate cost effective harvest on a larger scale. Transportation models were developed, which indicate that at a corn stover yield of 2.8 tons/acre and purchase price of $35/ton stover, it would be unprofitable to transport stover more than about 25 miles; thus suggesting the development of many regional collection centers. Therefore, collection centers should be located within about 30 miles of the farm, to keep transportation costs to an acceptable level. These collection centers could then potentially do some preprocessing (to fractionate or increase bulk density) and/or ship the biomass by rail or barge to the final customers. Wet storage of stover via ensilage was tested, but no clear economic advantages were evident. Wet storage eliminates fire risk, but increases the complexity of component separation and may result in a small loss of carbohydrate content (fermentation potential). A study of possible supplier-producer relationships, concluded that a “quasi-vertical” integration model would be best suited for new bioproducts industries based on stover. In this model, the relationship would involve a multiyear supply contract (processor with purchase guarantees, producer group with supply guarantees). Price will likely be fixed or calculated based on some formula (possibly a cost plus). Initial quality requirements will be specified (but subject to refinement).Producers would invest in harvest/storage/transportation equipment and the ...
Date: October 1, 2007
Creator: Aristidou, Aristos; Kean, Robert; Schechinger, Tom; Birrell, Stuart & Euken, Jill
Partner: UNT Libraries Government Documents Department

Test Plan for Evaluating Hammer and Fixed Cutter Grinders Using Multiple Varieties and Moistures of Biomass Feedstock

Description: Biomass preprocessing is a critical operation in the preparation of feedstock for the front-end of a cellulosic ethanol biorefinery. Its purpose is to chop, grind, or otherwise format the biomass material into a suitable feedstock for optimum conversion to ethanol and other bioproducts. Without this operation, the natural size, bulk density, and flowability characteristics of harvested biomass would decrease the capacities and efficiencies of feedstock assembly unit operations and biorefinery conversion processes to the degree that programmatic cost targets could not be met. The preprocessing unit operation produces a bulk flowable material that 1) improves handling and conveying efficiencies throughout the feedstock assembly system and biorefinery 2) increases biomass surface areas for improved pretreatment efficiencies, 3) reduces particle sizes for improved feedstock uniformity and density, and 4) fractionates structural components for improved compositional quality. The Idaho National Laboratory (INL) is tasked with defining the overall efficiency/effectiveness of current commercial hammer and fixed cutter grinding systems and other connecting systems such as harvest and collection, storage, transportation, and handling for a wide variety of feedstock types used in bioethanol or syngas production. This test plan details tasks and activities for two separate full-scale grinding tests: Material Characterization Test and Machine Characterization Test. For the Material Characterization Test, a small amount (~5-7 tons each) of several feedstock varieties will be ground. This test will define the fractionation characteristics of the grinder that affect the bulk density, particle size distribution, and quality of the size reduced biomass resulting from different separation screen sizes. A specific screen size will be selected based on the characteristics of the ground material. The Machine Characterization Test will then use this selected screen to grind several 30-ton batches of different feedstock varieties and moistures. This test will focus on identifying the performance parameters of the grinding system specific ...
Date: July 1, 2007
Creator: listed, Not
Partner: UNT Libraries Government Documents Department

Estimating canopy fuel parameters for Atlantic Coastal Plain forest types.

Description: Abstract It is necessary to quantify forest canopy characteristics to assess crown fire hazard, prioritize treatment areas, and design treatments to reduce crown fire potential. A number of fire behavior models such as FARSITE, FIRETEC, and NEXUS require as input four particular canopy fuel parameters: 1) canopy cover, 2) stand height, 3) crown base height, and 4) canopy bulk density. These canopy characteristics must be mapped across the landscape at high spatial resolution to accurately simulate crown fire. Currently no models exist to forecast these four canopy parameters for forests of the Atlantic Coastal Plain, a region that supports millions of acres of loblolly, longleaf, and slash pine forests as well as pine-broadleaf forests and mixed species broadleaf forests. Many forest cover types are recognized, too many to efficiently model. For expediency, forests of the Savannah River Site are categorized as belonging to 1 of 7 broad forest type groups, based on composition: 1) loblolly pine, 2) longleaf pine, 3) slash pine, 4) pine-hardwood, 5) hardwood-pine, 6) hardwoods, and 7) cypress-tupelo. These 7 broad forest types typify forests of the Atlantic Coastal Plain region, from Maryland to Florida.
Date: January 15, 2007
Creator: Parresol, Bernard, R.
Partner: UNT Libraries Government Documents Department