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  1. Simulated impact of the renewable fuels standard on US Conservation Reserve Program enrollment and conversion

    Hellwinckel, Chad ; Clark, Christopher ; Langholtz, Matthew ; ... - Global Change Biology. Bioenergy
    Abstract A socioeconomic model is used to estimate the land‐use implications on the U.S. Conservation Reserve Program from potential increases in second‐generation biofuel production. A baseline scenario with no second‐generation biofuel production is compared to a scenario where the Renewable Fuels Standard ( RFS 2) volumes are met by 2022. We allow for the possibility of converting expiring CRP lands to alternative uses such as conventional crops, dedicated second‐generation biofuel crops, or harvesting existing CRP grasses for biomass. Results indicate that RFS 2 volumes ( RFS 2‐v) can be met primarily with crop residues (78% of feedstock demand) and woodymore » residues (19% of feedstock demand) compared with dedicated biomass (3% of feedstock demand), with only minimal conversion of cropland (0.27 million hectares, <1% of total cropland), pastureland (0.28 million hectares of pastureland, <1% of total pastureland), and CRP lands (0.29 million hectares of CRP lands, 3% of existing CRP lands) to biomass production. Meeting RFS 2 volumes would reduce CRP re‐enrollment by 0.19 million hectares, or 4%, below the baseline scenario where RFS 2 is not met. Yet under RFS 2‐v scenario, expiring CRP lands are more likely to be converted to or maintain perennial cover, with 1.78 million hectares of CRP lands converting to hay production, and 0.29 million hectares being harvested for existing grasses. A small amount of CRP is harvested for existing biomass, but no conversion of CRP to dedicated biomass crops, such as switchgrass, are projected to occur. Although less land is enrolled in CRP under RFS 2‐v scenario, total land in perennial cover increases by 0.15 million hectares, or 2%, under RFS 2‐v. Sensitivity to yield, payment and residue retention assumptions are evaluated.« less

  2. Revised formulation of the macroscopic maxwell theory

    Neufeld, J. - Nuovo Cimento, B
    A modified version of the macroscopic Maxwell theory is developed with the purpose of removing some of the current contradictions and inconsistencies. One of the crucial problems of the current electromagnetic theory concerns the concept of energy. It appears that energy which has a clearly defined physical significance in all fields of physics has not been properly incorporated into the Maxwell-Lorentz theory. Therefore, the electromagnetic energy in a dissipative system as interpreted in the current version of the theory is not « energy » in the same sense as one usually interprets this concept in classical mechanics. The main objectmore » of this investigation is, therefore, to clarify the meaning of energy and to suggest a revised version in which the concept of energy is incorporated in accordance with the logical requirements of the theory. The proposed version is based on an assumption that the « electrical energy » both in nondissipative and dissipative media has a meaning only to the extent to which the electrical field theory can be developed as a theory of a dynamical system. This assumption leads to a formulation of a principle which states that the energy densityU e of an electrical field in an absorbing medium is determined solely by the electrical intensityE and is, therefore, independent of any parameter which represents absorption. The proposed version differs from the traditional theory in the interpretation of the dielectric constant and of conductivity. Further, the dielectric constant is considered to be independent of conductivity in the sense that a change in conductivity does not produce a corresponding alteration of the dielectric constant. Part I of this investigation deals with the fundamentals of the proposed reformulated version. These fundamentals are then applied in Part II to the generalization of Brillouin’s theory of wave propagation and group velocity to absorbing media.« less

  3. Revised formulation of the macroscopic maxwell theory

    Neufeld, J. - Nuovo Cimento, B
    The theory of energy propagation in dispersive media formulated by Brillouin is generalized and extended by taking into account energy attenuation or energy growth during the transmission process. Because of the exponential decay due to attenuation, the concept of propagation velocity of an electromagnetic disturbance can now be shown to have a physical meaning even if there is absorption, and in such a case the velocity of the disturbance is represented by the velocity of the point at which it attains its maximum intensity. Further, expressions are obtained for the energy density and the energy flow in an absorbing medium,more » and it is shown that the propagation velocity (a kinematic concept) is equal to the velocity of the energy transport. Such an equality is considered to be of fundamental interest since it supports the validity of the kinematic approach from the energetic point of view. Other aspects of energy transmission are discussed and analysed with particular reference to nonconvective and convective disturbances in absorbing and emitting media.« less

  4. Has the Sun Set on Quantum Dot-Sensitized Solar Cells?

    Wrenn, Toshia L. ; McBride, James R. ; Smith, Nathanael J. ; ... - Nanomaterials and Nanotechnology
    This is a reminder, a review and a look toward the future prospects for quantum dot-sensitized solar cells - a reminder of the highly viable, energy-efficient solar cells achievable. This is also a review of ground-breaking devices and their similarities to the near unity photon-to-electron mechanisms of photosynthesis; a look toward architectures that capitalize on the advances observed in previous work.

  5. Hard Photodisintegration of a Proton Pair

    Pomerantz, Ishay ; Bubis, Nathaniel ; Allada, Kalyan ; ... - Physics Letters. B
    We present the first study of high energy photodisintegration of proton-pairs through the gamma + 3He -> p+p+n channel. Photon energies from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. An s^{-11} scaling of the cross section was observed, as predicted by the constituent counting rule. The onset of the scaling is at a higher energy and the cross section is significantly lower then for pn pair photodisintegration. For photon energies below the scaling region, the scaled cross section was found to present a strongmore » energy-dependent structure not observed in deuteron photodisintegration.« less

  6. Differential cross sections for the reactions γ p → p η and γ p → p η '

    Williams, M. ; Krahn, Z. ; Applegate, D. ; ... - Physical Review C, Nuclear Physics
    In high-statistics differential cross sections for the reactions γ p -> p η and γ p -> p η' the CLAS at Jefferson Lab was used to measure the center-of-mass energies from near threshold up to 2.84 GeV. The eta-prime results are the most precise to date and provide the largest energy and angular coverage. The eta measurements extend the energy range of the world's large-angle results by approximately 300 MeV. These new data, in particular the η' measurements, are likely to help constrain the analyses being performed to search for new baryon resonance states.

  7. Revised formulation of the kinetic plasma theory

    Neufeld, Jacob - International Journal of Electronics
    Using the Maxwellian macroscopic approach and analysing the formulation of the dielectric constant, it is shown that the concept of energy has not been properly incorporated into the current kinetic plasma theory. The difficulties are due to the Boltzmann collisional term (∂F/∂t)coll which accounts for a change in the velocity distribution due to collisions alone. If one attempts to rephrase the Boltzmann-Vlasov theory in terms of the Maxwellian macroscopic formulation, one obtains an expression for energy which is not consistent with the meaning of this concept in generalized dynamics. In a revised version developed in this analysis the Boltzmann collisionalmore » term has been eliminated and an appropriate collisional operator is introduced which is believed to describe more adequately collisional processes in a plasma. Here, it is assumed that the collisional operator can be applied directly to the electrical intensity of the field interacting with the plasma and is effective in transforming the intensity in a collisionless plasma into a corresponding intensity in a collisional plasma. At the same time the relationship between the electron velocity distribution function and the field intensity is considered to be the same, whether there are collisions or not. In other words, not only a collisionless but also a collisional plasma are assumed to be controlled by a Vlasov type mechanism which does not take into account explicitly the Boltzmann term (∂F/∂t)coll.« less

  8. Neutron-deficient Mercury Isotopes1

    Fink, Richard W. ; Wiig, Edwin O. - Journal of the American Chemical Society
    In this work, high energy bombardments with protons on gold and α-particles on platinum were performed to study neutron-deficient mercury isotopes. Two new mercury isotopes have been definitely identified: Hg192, T1/2 = 5.7 ± 0.5 hours, 1.18 mev. ß+, 0.18 mev. conversion electrons, K, L X-rays and 1.39 mev. γ-ray; parent of 4.0 hour Au192. Hg193, T1/2 = 10.0 ± 0.5 hours Noß+, K, L X-rays, 0.18 mev. conversion electrons; parent of 15.3 hour Au193. Tentatively identified was Hg195 of 31 hour half-life, although this value may be in error owing to masking by the isomeric pair at Hg197. Decaymore » of Hg195 leaves gold daughter of 180-day half-life; although this genetic relation has not been established quantitatively, long-lived gold daughter has been observed. No positrons are emitted by Hg195 but K and L X-rays are detected. No activity was found which canbe allocated to Hg194. Positron-emitting 39.5-hour Au194 was not present among the gold daughters. An unidentified 2.0-hour mercury activity, present in increasing yield with increasing proton bombardment energy, must have mass number 191 or lower. Finally, the genetic relationships between Hg192-Au192 and between Hg193-Au193 have been established quantitatively.« less

  9. Heat of Adsorption of Argon Adsorbed on Titanium Dioxide between 60 and 90 °K.

    Pace, E. L. ; Greene, S. A. - Journal of the American Chemical Society
    The heat of adsorption of argon on titanium dioxide has been measured with a modified Nernst-Giauque calorimeter at temperatures of 63.5, 73.0, 78.5 and 86.5°K. for concentrations ranging to a maximum value of the order of a monolayer. The heat capacity of the adsorbed phase was determined between 55 and 90°K. in the same range of concentrations. By-using the heat capacity data it was found possible to reduce the experimentally determined differential heats of adsorption at 73.0, 78.5 and 86.5 to a single curve at 63.5°K. within the experimental error. Therefore, at these temperatures, it is believed that the experimentalmore » method has yielded" thermodynamically reversible results. Further, the results of the experimental measurements at 63.5°K do not fall on the single curve, and consequently the adsorption process appears to be metastable at this temperature. The differential heat curves for the equilibrium and non-equilibrium processes have been used to determine the corresponding energy distribution at the sites of adsorption.« less

  10. Outline for an acceptable nuclear future

    Weinberg, Alvin M. - Energy
    Nuclear energy is likely to develop in two phases. Phase I, based on burner reactors, is self-limiting because the reserve of uranium is limited. Phase II, based on breeders, might last for an extremely long time. It is suggested that opposition to Phase I of nuclear energy might be reduced if an acceptable Phase II can be constructed. Elements of an acceptable Phase II might include isolated and collocated energy centers with resident IAEA inspectors; heavier security; professionalization of the nuclear cadre; immortality of the operating entities; and separation of generation and distribution. Though these measures are aimed primarily atmore » increasing the safety and reliability of the nuclear system, it is suggested that the proposed siting policy, with IAEA resident inspection, might be more proliferation-resistant than is the current dispersed system.« less
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