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The effect of location and facility demand on the marginal cost of delivered wood chips from energy crops: A case study of the state of Tennessee

Description: Cost-supply curves for delivered wood chips from short rotation woody crops were calculated for 21 regularly-spaced locations spanning the state of Tennessee. These curves were used to systematically evaluate the combined effects of location and facility demand on wood chip feedstock costs in Tennessee. The cost-supply curves were developed using BRAVO, a GIS-based decision support system which calculates marginal cost of delivering wood chips to a specific location given road network maps and maps of farmgate prices and supplies of woody chips from short rotation energy crops. Marginal costs of delivered chips varied by both facility location in the state and facility demand. Marginal costs were lowest in central Tennessee unless the facility demand was greater than 2.7 million dry Mg per year (3 million dry tons per year) in which case west Tennessee was the lowest cost region. Marginal costs rose rapidly with increasing facility demand in the mountainous eastern portion of the state. Transportation costs accounted for 18 to 29% of the delivered cost and ranged between $8 and $18/dry Mg ($7 and $16/dry ton). Reducing the expected farmer participation rate from 100% to 50% or 25% dramatically raised the marginal costs of feedstock supply in the east and central regions of the state. The analysis demonstrates the need to use geographically-specific information when projecting the potential costs and supplies of biomass feedstock.
Date: December 31, 1995
Creator: Graham, R.L.; Liu, W.; Downing, M.; Noon, C.; Daly, M. & Moore, A.
Partner: UNT Libraries Government Documents Department

Amorphous thin films for solar-cell applications. Quarterly report No. 1, 11 September-10 December 1979

Description: Research progress on amorphous Si:H solar cells is described. Tasks include theoretical modeling, deposition and doping studies, experimental characterization of a-Si:H, formation of solar cell structures, and evaluation of solar cell parameters. A new method for determining the drift mobility of majority carriers in doped a-Si:H is discussed. Deposition and doping studies have been performed in an rf magnetron discharge system. Mass spectroscopy has been used to show that the major impurities in the SiH/sub 4/ discharge occur at m/e values of 45, 47, and 49 at concentrations 10/sup -4/-10/sup -5/ times that of the principal ion, SiH/sub 3//sup +/. Boron implantation of an i-n structure produces a p-i-n cell with an enhanced V/sub oc/ but reduced J/sub sc/ as compared to cells in a nonimplanted region. Laser annealing at power densities up to 60 MW/cm/sup 2/ (30-ns pulse) causes partial crystallization of the a-Si:H, but there are no significant changes in the photoluminescence spectrum or the hydrogen content. the photo-Hall effect in undoped a-Si:H has been measured as a function of wave-length and temperature. The photoelectromagnetic spectrum for the short-circuit current has been used to estimate a hole diffusion length of approx.0.1-0.3 ..mu..m in undoped a-Si:H. Recently p-i-n cells have been fabricated with conversion efficiencies up to approx. 4.5%. Both boron and phosphorus concentrations were found to vary inversely with rf power for doped a-Si:H films made in an rf capacitive discharge. Solar cells have also been fabricated with a-(Si,Ge):H alloys. (WHK)
Date: December 1, 1979
Creator: Carlson, D. E.; Crandall, R. S.; Dresner, J.; Goldstein, B.; Hanak, J. J.; Moore, A. R. et al.
Partner: UNT Libraries Government Documents Department

Amorphous thin films for solar-cell applications. Quarterly report No. 2, 11 December 1979-10 March 1980

Description: Measurements of both primary and secondary photocurrents for photon energies between 0.58 and 2.0 eV in a-Si:H solar-cell structures have been used to provide information about the density of states above the valence band as well as show that holes are mobile deep in the bandgap. The drift mobility is independent of excitation energy, indicating that the majority carriers are excited to the same states, irrespective of the excitation energy. Deposition studies in the dc proximity system have shown that the conductivity and photoconductivity of doped films (both boron- and phosphorus-doped) increase with substrate temperature. Mass spectroscopy studies have shown that the larger Si/sub x/H/sub y//sup +/ clusters are favored by operating rf discharges at low rf powers and high pressures. The Hall mobility is roughly constant below 360 K but exhibits a thermal activation energy of approx. 0.13 eV at higher temperatures. These observations rule out simple extended-state transport as the conduction mechanism. The photoelectromagnetic effect has been used to estimate the hole lifetime (approx. 3.4 x 10/sup -7/s) in undoped a-Si:H; the electron lifetime is approx. 1.7 x 10/sup -6/s. An a-Si:H monolithic solar panel consisting of 16 cells in series has been fabricated on a 4'' x 4'' glass substrate (63 cm/sup 2/ of active area), and the panel exhibits a conversion efficiency of 3.6%. In another series of experiments, the thicknesses and doping levels of p-i-n cells made in a dc(P) discharge were optimized. The best cell made in these experiments had an efficiency of 5.3% with an area of 1.19 cm/sup 2/.
Date: March 1, 1980
Creator: Carlson, D. E.; Crandall, R. S.; Dresner, J.; Goldstein, B.; Hanak, J. J.; Moore, A. R. et al.
Partner: UNT Libraries Government Documents Department

Comparison of 3D Maximum A Posteriori and Filtered Backprojection algorithms for high resolution animal imaging in microPET

Description: We have evaluated the performance of two three dimensional reconstruction algorithms with data acquired from microPET, a high resolution tomograph dedicated to small animal imaging. The first was a linear filtered-backprojection algorithm (FBP) with reprojection of the missing data and the second was a statistical maximum-aposteriori probability algorithm (MAP). The two algorithms were evaluated in terms of their resolution performance, both in phantoms and in vivo. Sixty independent realizations of a phantom simulating the brain of a baby monkey were acquired, each containing 3 million counts. Each of these realizations was reconstructed independently with both algorithms. The ensemble of the sixty reconstructed realizations was used to estimate the standard deviation as a measure of the noise for each reconstruction algorithm. More detail was recovered in the MAP reconstruction without an increase in noise relative to FBP. Studies in a simple cylindrical compartment phantom demonstrated improved recovery of known activity ratios with MAP. Finally in vivo studies also demonstrated a clear improvement in spatial resolution using the MAP algorithm. The quantitative accuracy of the MAP reconstruction was also evaluated by comparison with autoradiography and direct well counting of tissue samples and was shown to be superior.
Date: January 1, 2000
Creator: Chatziioannou, A.; Qi, J.; Moore, A.; Annala, A.; Nguyen, K.; Leahy, R.M. et al.
Partner: UNT Libraries Government Documents Department

A soft x-ray transmission grating imaging-spectrometer for the National Ignition Facility

Description: A soft x-ray transmission grating spectrometer has been designed for use on high energy-density physics experiments at the National Ignition Facility (NIF); coupled to one of the NIF gated x-ray detectors (GXD) it records sixteen time-gated spectra between 250 and 1000eV with 100ps temporal resolution. The trade-off between spectral and spatial resolution leads to an optimized design for measurement of emission around the peak of a 100-300eV blackbody spectrum. Performance qualification results from the NIF, the Trident Laser Facility and VUV beamline at the National Synchrotron Light Source (NSLS), evidence a <100{micro}m spatial resolution in combination with a source-size limited spectral resolution that is <10eV at photon energies of 300eV.
Date: May 1, 2012
Creator: Moore, A S; Guymer, T M; Kline, J L; Morton, J; Taccetti, M; Lanier, N E et al.
Partner: UNT Libraries Government Documents Department