A hydrogen energy carrier. Volume 2: Systems analysis

A systems analysis of hydrogen as an energy carrier in the United States indicated that it is feasible to use hydrogen in all energy use areas, except some types of transportation. These use areas are industrial, residential and commercial, and electric power generation. Saturation concept and conservation concept forecasts of future total energy demands were made. Projected costs of producing hydrogen from coal or from nuclear heat combined with thermochemical decomposition of water are in the range $1.00 to$1.50 per million Btu of hydrogen produced. Other methods are estimated to be more costly. The use of hydrogen as a fuel will require the development of large-scale transmission and storage systems. A pipeline system similar to the existing natural gas pipeline system appears practical, if design factors are included to avoid hydrogen environment embrittlement of pipeline metals. Conclusions from the examination of the safety, legal, environmental, economic, political and societal aspects of hydrogen fuel are that a hydrogen energy carrier system would be compatible with American values and the existing energy system

A hydrogen energy carrier. Volume 1: Summary

The production, technology, transportation, and implementation of hydrogen into the energy system are discussed along with the fossil fuel cycle, hydrogen fuel cycle, and the demands for energy. The cost of hydrogen production by coal gasification; electrolysis by nuclear energy, and solar energy are presented. The legal aspects of a hydrogen economy are also discussed

Dethinning Extensive Air Shower Simulations

We describe a method for restoring information lost during statistical thinning in extensive air shower simulations. By converting weighted particles from thinned simulations to swarms of particles with similar characteristics, we obtain a result that is essentially identical to the thinned shower, and which is very similar to non-thinned simulations of showers. We call this method dethinning. Using non-thinned showers on a large scale is impossible because of unrealistic CPU time requirements, but with thinned showers that have been dethinned, it is possible to carry out large-scale simulation studies of the detector response for ultra-high energy cosmic ray surface arrays. The dethinning method is described in detail and comparisons are presented with parent thinned showers and with non-thinned showers

Investigation of Mobility Limiting Mechanisms in Undoped Si/SiGe Heterostructures

We perform detailed magnetotransport studies on two-dimensional electron gases (2DEGs) formed in undoped Si/SiGe heterostructures in order to identify the electron mobility limiting mechanisms in this increasingly important materials system. By analyzing data from 26 wafers with different heterostructure growth profiles we observe a strong correlation between the background oxygen concentration in the Si quantum well and the maximum mobility. The highest quality wafer supports a 2DEG with a mobility of 160,000 cm^2/Vs at a density 2.17 x 10^11/cm^2 and exhibits a metal-to-insulator transition at a critical density 0.46 x 10^11/cm^2. We extract a valley splitting of approximately 150 microeV at a magnetic field of 1.8 T. These results provide evidence that undoped Si/SiGe heterostructures are suitable for the fabrication of few-electron quantum dots.Comment: Related papers at http://pettagroup.princeton.ed

Background light measurements at the DUMAND site

Ambient light intensities at the DUMAND site, west of the island of Hawaii were measured around the one photoelectron level. Throughout the water column between 1,500m and 4,700m, a substantial amount of stimulateable bioluminescence is observed with a ship suspended detector. But non-stimulated bioluminescence level is comparable, or less than, K sup 40 background, when measured with a bottom tethered detector typical of a DUMAND optical module

Piezoelectricity: Quantized Charge Transport Driven by Adiabatic Deformations

We study the (zero temperature) quantum piezoelectric response of Harper-like models with broken inversion symmetry. The charge transport in these models is related to topological invariants (Chern numbers). We show that there are arbitrarily small periodic modulations of the atomic positions that lead to nonzero charge transport for the electrons.Comment: Latex, letter. Replaced version with minor change in style. 1 fi

Constraining mass ratio and extinction in the FU Orionis binary system with infrared integral field spectroscopy

We report low resolution near infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0.5" south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J and H band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low resolution near infrared spectrum in conjunction with 10.2 micron interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, A_V =8-12, with an effective temperature of ~ 4000-6500 K . Finally we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary syste