Science.gov

Sample records for low energy transitions

  1. Exchange and relaxation effects in low-energy radiationless transitions

    NASA Technical Reports Server (NTRS)

    Chen, M. H.; Crasemann, B.; Aoyagi, M.; Mark, H.

    1978-01-01

    The effect on low-energy atomic inner-shell Coster-Kronig and super Coster-Kronig transitions that is produced by relaxation and by exchange between the continuum electron and bound electrons was examined and illustrated by specific calculations for transitions that deexcite the 3p vacancy state of Zn. Taking exchange and relaxation into account is found to reduce, but not to eliminate, the discrepancies between theoretical rates and measurements.

  2. Energy at the Frontier: Low Carbon Energy System Transitions and Innovation in Four Prime Mover Countries

    NASA Astrophysics Data System (ADS)

    Araujo, Kathleen M.

    All too often, discussion about the imperative to change national energy pathways revolves around long timescales and least cost economics of near-term energy alternatives. While both elements certainly matter, they don't fully reflect what can drive such development trajectories. This study explores national energy transitions by examining ways in which four prime mover countries of low carbon energy technology shifted away from fossil fuels, following the first global oil crisis of 1973. The research analyzes the role of readiness, sectoral contributions and adaptive policy in the scale-up and innovations of advanced, alternative energy technologies. Cases of Brazilian biofuels, Danish wind power, French nuclear power and Icelandic geothermal energy are analyzed for a period of four decades. Fundamentally, the research finds that significant change can occur in under 15 years; that technology complexity need not necessarily impede change; and that countries of different governance approaches and consumption levels can effectuate such transitions. This research also underscores that low carbon energy technologies may be adopted before they are competitive and then become competitive in the process. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

  3. Emittance and Energy Measurements of Low-Energy Electron Beam Using Optical Transition Radiation Techniques

    NASA Astrophysics Data System (ADS)

    Sakamoto, Fumito; Iijima, Hokuto; Dobashi, Katsuhiro; Imai, Takayuki; Ueda, Toru; Watanabe, Takahiro; Uesaka, Mitsuru

    2005-03-01

    Emittance and energy of an electron beam in the range of 8 to 22 MeV were measured via optical transition radiation (OTR) techniques. The beam divergence effect on observations of the far-field OTR image at low energies was studied by means of numerical analysis. The numerical analysis indicates that if the beam divergence is under 1.5 mrad, a simultaneous single-shot measurement of emittance and energy is possible. The results of the single-shot experiment agree with independent measurements conducted using the quadrupole scan method and an electron spectrometer. The experiments were performed with an S-band linac at the Nuclear Engineering Research Laboratory, The University of Tokyo (UTNL).

  4. Energies and Electric Dipole Transitions for Low-Lying Levels of Protactinium IV and Uranium V

    NASA Astrophysics Data System (ADS)

    Ürer, Güldem; Özdemir, Leyla

    2012-02-01

    We have reported a relativistic multiconfiguration Dirac-Fock (MCDF) study on low-lying level structures of protactinium IV (Z =91) and uranium V (Z =92) ions. Excitation energies and electric dipole (E1) transition parameters (wavelengths, oscillator strengths, and transition rates) for these low-lying levels have been given. We have also investigated the influence of the transverse Breit and quantum electrodynamic (QED) contributions besides correlation effects on the level structure. A comparison has been made with a few available data for these ions in the literature.

  5. Activation energy of the low-load NaCl transition from nanoindentation loading curves.

    PubMed

    Kaupp, Gerd

    2014-01-01

    Access to activation energies E(a) of phase transitions is opened by unprecedented analyses of temperature dependent nanoindentation loading curves. It is based on kinks in linearized loading curves, with additional support by coincidence of kink and electrical conductivity of silicon loading curves. Physical properties of B1, B2, NaCl and further phases are discussed. The normalized low-load transition energy of NaCl (Wtrans/µN) increases with temperature and slightly decreases with load. Its semi-logarithmic plot versus T obtains activation energy E(a)/µN for calculation of the transition work for all interesting temperatures and pressures. Arrhenius-type activation energy (kJ/mol) is unavailable for indentation phase transitions. The E(a) per load normalization proves insensitive to creep-on-load, which excludes normalization to depth or volume for large temperature ranges. Such phase transition E(a)/µN is unprecedented material's property and will be of practical importance for the compatibility of composite materials under impact and further shearing interactions at elevated temperatures.

  6. Earth-to-Moon low energy transfers targeting L1 hyperbolic transit orbits.

    PubMed

    Topputo, Francesco; Vasile, Massimiliano; Bernelli-Zazzera, Franco

    2005-12-01

    In the frame of the lunar exploration, numerous future space missions will require maximization of payload mass, and simultaneously achieving reasonable transfer times. To fulfill this request, low energy non-Keplerian orbits could be used to reach the Moon instead of high energetic transfers. The low energy solutions can be separated into two main categories depending on the nature of the trajectory approaching the Moon: low energy transit orbits that approach the Moon from the interior equilibrium point L(1) and weak stability boundary transfers that reach the Moon after passing through L(2). This paper proposes an alternative way to exploit the opportunities offered by L(1) transit orbits for the design of Earth-Moon transfers. First, in a neighborhood of the L(1) point, the three-body dynamics is linearized and written in normal form; then the entire family of nonlinear transit orbits is obtained by selecting the appropriate nontrivial amplitudes associated with the hyperbolic part. The L(1)-Earth arc is close to a 5:2 resonant orbit with the Moon, whose perturbations cause the apogee to rise. In a second step, two selected low altitude parking orbits around the Earth and the Moon are linked with the transit orbit by means of two three-body Lambert arcs, solutions of two two-point boundary value problems. The resulting Earth-to-Moon trajectories prove to be very efficient in the Moon captured arc and save approximately 100 m/sec in Deltav cost when compared to the Hohmann transfer. Furthermore, such solutions demonstrate that Moon capture could be obtained in the frame of the Earth-Moon R3BP neglecting the presence of the Sun.

  7. Free-Free Transitions in the Presence of Laser Fields at Very Low Incident Electron Energy

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand K.; Sinha, Chandana

    2009-01-01

    We study the free-free transition in electron-hydrogenic systems in ground state in presence of an external laser field at very low incident energies. The laser field is treated classically while the collision dynamics is treated quantum mechanically. The laser field is chosen to be monochromatic, linearly polarized and homogeneous. The incident electron is considered to be dressed by the laser in a nonperturbative manner by choosing a Volkov wave function for it The scattering wave function for the electron is solved numerically by taking into account the effect of the electron exchange, short-range as well as of the long-range interactions to get the S and P wave phase shifts while for the higher angular momentum phase shifts, the exchange approximation has only been considered. We calculate the laser-assisted differential cross sections (LADCS) for the aforesaid free-free transition process for single photon absorption/emission. The laser intensity is chosen to be much less than the atomic field intensity. A strong suppression is noted in the LADCS as compared to the field free (FF) cross sections. Unlike the FF ones, the LADCS exhibit some oscillations having a distinct maximum at a low value of the scattering angle depending on the laser parameters as well as on the incident energies.

  8. Reactive collisions of very low-energy electrons with H_2+: rotational transitions and dissociative recombination

    NASA Astrophysics Data System (ADS)

    Epée Epée, M. D.; Mezei, J. Zs; Motapon, O.; Pop, N.; Schneider, I. F.

    2016-01-01

    A new series of computations has been performed to obtain cross-sections and rate coefficients for state-to-state rotational transitions in the H2+ ion, induced by collisions with very low-energy electrons. Following our recent work on the HD+ ion (Motapon et al. 2014), and using the same molecular structure data sets, excitations Ni+ rArr Ni++2 for Ni+=0 to 10, and de-excitations Ni+ → Ni+-2, for Ni+=2 to 10, in the energy range 0.01 meV-0.3 eV, have been explored. The calculated cross-sections have been convolved in order to obtain Maxwell rate coefficients for electronic temperatures up to a few hundred of Kelvin. Moreover, Maxwell rate coefficients for dissociative recombination have been calculated for the same initial rotational levels.

  9. Optical transition radiation used in the diagnostic of low energy and low current electron beams in particle accelerators

    SciTech Connect

    Silva, T. F.; Bonini, A. L.; Lima, R. R.; Maidana, N. L.; Malafronte, A. A.; Pascholati, P. R.; Vanin, V. R.; Martins, M. N.

    2012-09-15

    Optical transition radiation (OTR) plays an important role in beam diagnostics for high energy particle accelerators. Its linear intensity with beam current is a great advantage as compared to fluorescent screens, which are subject to saturation. Moreover, the measurement of the angular distribution of the emitted radiation enables the determination of many beam parameters in a single observation point. However, few works deals with the application of OTR to monitor low energy beams. In this work we describe the design of an OTR based beam monitor used to measure the transverse beam charge distribution of the 1.9-MeV electron beam of the linac injector of the IFUSP microtron using a standard vision machine camera. The average beam current in pulsed operation mode is of the order of tens of nano-Amps. Low energy and low beam current make OTR observation difficult. To improve sensitivity, the beam incidence angle on the target was chosen to maximize the photon flux in the camera field-of-view. Measurements that assess OTR observation (linearity with beam current, polarization, and spectrum shape) are presented, as well as a typical 1.9-MeV electron beam charge distribution obtained from OTR. Some aspects of emittance measurement using this device are also discussed.

  10. Optical transition radiation used in the diagnostic of low energy and low current electron beams in particle accelerators.

    PubMed

    Silva, T F; Bonini, A L; Lima, R R; Maidana, N L; Malafronte, A A; Pascholati, P R; Vanin, V R; Martins, M N

    2012-09-01

    Optical transition radiation (OTR) plays an important role in beam diagnostics for high energy particle accelerators. Its linear intensity with beam current is a great advantage as compared to fluorescent screens, which are subject to saturation. Moreover, the measurement of the angular distribution of the emitted radiation enables the determination of many beam parameters in a single observation point. However, few works deals with the application of OTR to monitor low energy beams. In this work we describe the design of an OTR based beam monitor used to measure the transverse beam charge distribution of the 1.9-MeV electron beam of the linac injector of the IFUSP microtron using a standard vision machine camera. The average beam current in pulsed operation mode is of the order of tens of nano-Amps. Low energy and low beam current make OTR observation difficult. To improve sensitivity, the beam incidence angle on the target was chosen to maximize the photon flux in the camera field-of-view. Measurements that assess OTR observation (linearity with beam current, polarization, and spectrum shape) are presented, as well as a typical 1.9-MeV electron beam charge distribution obtained from OTR. Some aspects of emittance measurement using this device are also discussed.

  11. Free-Free Transitions in the Presence of Laser Fields at Very Low Incident Electron Energy

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Sinha, Chandana

    2010-01-01

    We study the free-free transition in electron-hydrogenic systems in ground state in presence of an external laser field at very loud incident energies. The laser field is treated classically while the collision dynamics is treated quantum mechanically. The laser field is chosen to be monochromatic, linearly polarized and homogeneous. The incident electron is considered to be dressed by the laser in a nonperturbative manner by choosing a Volkov wave function for it. The scattering weave function for the electron is solved numerically by taking into account the effect of the electron exchange, short-range as well as of the long-range interactions to get the S and P wave phase shifts while for the higher angular momentum phase shifts the exchange approximation has only been considered. We calculate the laser assisted differential cross sections (LADCS) for the aforesaid free-free transition process for single photon absorption/emission. The laser intensity is chosen to be much less than the atomic field intensity. A strong suppression is noted in the LADCS as compared to the field free (FF) cross sections. Unlike the FF ones, the LADCS exhibit some oscillations having a distinct maximum at a low value of the scattering angle depending on the laser parameters as well as on the incident energies.

  12. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    SciTech Connect

    Hirano, Y. E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp; Kiyama, S.; Koguchi, H.; Fujiwara, Y.; Sakakita, H.

    2015-11-15

    A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  13. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region.

    PubMed

    Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H

    2015-11-01

    A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  14. Land use impacts of low-carbon energy system transition - the case of UK bioenergy deployment under the Carbon Plan

    NASA Astrophysics Data System (ADS)

    Konadu, D. D.; Sobral Mourao, Z.; Lupton, R.; Skelton, S.

    2015-12-01

    The UK Department of Energy and Climate Change has developed four low-carbon energy transition pathways - the Carbon Plan - towards achieving the legally binding 80% territorial greenhouse gas emissions reduction, stipulated in the 2008 Climate Change Act by 2050. All the pathways require increase in bioenergy deployment, of which a significant amount could be indigenously sourced from crops. But will increased domestic production of energy crops conflict with other land use and ecosystem priorities? To address this question, a coupled analysis of the four energy transition pathways and land use has been developed using an integrated resource accounting platform called ForeseerTM. The two systems are connected by the bioenergy component, and are projected forward in time to 2050, under different scenarios of energy crop composition and yield, and accounting for various constraints on land use for agriculture and ecosystem services. The results show between 7 and 61% of UK agricultural land could be required to meet bioenergy deployment projections under different combinations of crop yield and compositions for the transition pathways. This could result in competition for land for food production and other socio-economic and ecological land uses. Consequently, the potential role of bioenergy in achieving UK emissions reduction targets may face significant deployment challenges.

  15. Excitation of the lowest electronic transitions in ethanol by low-energy electrons

    NASA Astrophysics Data System (ADS)

    Hargreaves, L. R.; Khakoo, M. A.; Winstead, C.; McKoy, V.

    2016-09-01

    We report absolute differential and integral cross sections for electronic excitation of ethanol, by low-energy electron impact. Cross sections for low-lying excited states were measured at incident electron energies from 9 to 20 eV and at scattering angles from {5}\\circ through {130}\\circ . Our results include cross sections for excitation of the 1{}3A\\prime \\prime and 1{}1A\\prime \\prime states as well as for the 2{}3A\\prime \\prime + 1{}3A\\prime and 2{}1A\\prime \\prime + 2{}1A\\prime cross section sums. Corresponding calculations were also performed using the Schwinger multichannel method, within an 11-channel close-coupling scheme.

  16. Free-Free Transitions in the Presence of Laser Fields and Debye Potential at Very Low Incident Electron Energies

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand

    2012-01-01

    We study the free-free transition in electron-helium ion in the ground state and embedded in a Debye potential in the presence of an external laser field at very low incident electron energies. The laser field is treated classically while the collision dynamics is treated quantum mechanically. The laser field is chosen as monochromatic, linearly polarized and homogeneous. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing Volkov wave function for it. The scattering wave function for the incident electron on the target embedded in a Debye potential is solved numerically by taking into account the effect of electron exchange. We calculate the laser-assisted differential and total cross sections for free-free transition for absorption/emission of a single photon or no photon exchange. The results will be presented at the conference.

  17. Free-free transitions in the presence of laser fields and Debye potential at very low incident electron energies

    NASA Astrophysics Data System (ADS)

    Bhatia, Anand

    2012-06-01

    We study the free-free transition in electron-helium ion in the ground state and embedded in a Debye potential in the presence of an external laser field at very low incident electron energies. The laser field is treated classically while the collision dynamics is treated quantum mechanically. The laser field is chosen as monochromatic, linearly polarized and homogeneous. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing Volkov wave function for it. The scattering wave function for the incident electron on the target embedded in a Debye potential is solved numerically by taking into account the effect of electron exchange. We calculate the laser-assisted differential and total cross sections for free-free transition for absorption/emission of a single photon or no photon exchange. The results will be presented at the conference.

  18. Free-free transitions in the presence of laser fields and Debye potential at very low incident electron energies

    NASA Astrophysics Data System (ADS)

    Bhatia, Anand

    2013-05-01

    We study the free-free transition in e-He+ system in the ground state and embedded in a Debye potential in the presence of an external laser field which is monochromatic, linearly polarized and homogeneous, at very low incident electron energies. The laser field is treated classically while the collision dynamics is treated quantum mechanically. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing Volkov wave function. The scattering function for the incident electron on the target is solved numerically by taking into account the effect of electron exchange. We calculate the laser-assisted differential and total cross sections for free-free transitions for absorption/emission of a single photon or no photon exchange. The cross sections for e-He+ system are much larger than e-H system. The results will be presented at the conference.

  19. Activation Energy of the Low-pH-Induced Lamellar to Bicontinuous Cubic Phase Transition in Dioleoylphosphatidylserine/Monoolein.

    PubMed

    Oka, Toshihiko; Saiki, Takahiro; Alam, Jahangir Md; Yamazaki, Masahito

    2016-02-01

    Electrostatic interaction is an important factor for phase transitions between lamellar liquid-crystalline (Lα) and inverse bicontinuous cubic (QII) phases. We investigated the effect of temperature on the low-pH-induced Lα to double-diamond cubic (QII(D)) phase transition in dioleoylphosphatidylserine (DOPS)/monoolein (MO) using time-resolved small-angle X-ray scattering with a stopped-flow apparatus. Under all conditions of temperature and pH, the Lα phase was directly transformed into an intermediate inverse hexagonal (HII) phase, and subsequently the HII phase slowly converted to the QII(D) phase. We obtained the rate constants of the initial step (i.e., the Lα to HII phase transition) and of the second step (i.e., the HII to QII(D) phase transition) using the non-negative matrix factorization method. The rate constant of the initial step increased with temperature. By analyzing this result, we obtained the values of its apparent activation energy, Ea (Lα → HII), which did not change with temperature but increased with an increase in pH. In contrast, the rate constant of the second step decreased with temperature at pH 2.6, although it increased with temperature at pH 2.7 and 2.8. These results indicate that the value of Ea (HII → QII(D)) at pH 2.6 increased with temperature, but the values of Ea (HII → QII(D)) at pH 2.7 and 2.8 were constant with temperature. The values of Ea (HII → QII(D)) were smaller than those of Ea (Lα → HII) at the same pH. We analyzed these results using a modified quantitative theory on the activation energy of phase transitions of lipid membranes proposed initially by Squires et al. (Squires, A. M.; Conn, C. E.; Seddon, J. M.; Templer, R. H. Soft Matter 2009, 5, 4773). On the basis of these results, we discuss the mechanism of this phase transition.

  20. Activation Energy of the Low-pH-Induced Lamellar to Bicontinuous Cubic Phase Transition in Dioleoylphosphatidylserine/Monoolein.

    PubMed

    Oka, Toshihiko; Saiki, Takahiro; Alam, Jahangir Md; Yamazaki, Masahito

    2016-02-01

    Electrostatic interaction is an important factor for phase transitions between lamellar liquid-crystalline (Lα) and inverse bicontinuous cubic (QII) phases. We investigated the effect of temperature on the low-pH-induced Lα to double-diamond cubic (QII(D)) phase transition in dioleoylphosphatidylserine (DOPS)/monoolein (MO) using time-resolved small-angle X-ray scattering with a stopped-flow apparatus. Under all conditions of temperature and pH, the Lα phase was directly transformed into an intermediate inverse hexagonal (HII) phase, and subsequently the HII phase slowly converted to the QII(D) phase. We obtained the rate constants of the initial step (i.e., the Lα to HII phase transition) and of the second step (i.e., the HII to QII(D) phase transition) using the non-negative matrix factorization method. The rate constant of the initial step increased with temperature. By analyzing this result, we obtained the values of its apparent activation energy, Ea (Lα → HII), which did not change with temperature but increased with an increase in pH. In contrast, the rate constant of the second step decreased with temperature at pH 2.6, although it increased with temperature at pH 2.7 and 2.8. These results indicate that the value of Ea (HII → QII(D)) at pH 2.6 increased with temperature, but the values of Ea (HII → QII(D)) at pH 2.7 and 2.8 were constant with temperature. The values of Ea (HII → QII(D)) were smaller than those of Ea (Lα → HII) at the same pH. We analyzed these results using a modified quantitative theory on the activation energy of phase transitions of lipid membranes proposed initially by Squires et al. (Squires, A. M.; Conn, C. E.; Seddon, J. M.; Templer, R. H. Soft Matter 2009, 5, 4773). On the basis of these results, we discuss the mechanism of this phase transition. PMID:26766583

  1. More light on the low electronic transition energy bands of dithizone

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. R.; El Gaber, A. A. Abd; El Roudi, A. M.; Soliman, E. M.

    The visible electronic spectral behaviour of different concentrations of dithizone in pure and mixed various organic solvents has been investigated. It is identified that in dilute basic solvents solutions, dithizone (H 2DZ) exists mainly in monovalent anionic form (HDZ -), where its extent of ionization is largely dependent on the solvent basicity effect. The visible absorption band belonging to absorption of HDZ - form and the shorter visible one belonging to absorption of H 2DZ form are assigned to a transition involving the whole solute associated with intramolecular CT interaction. On the other hand, the longer wavelength visible band observed in the spectrum of the H 2DZ form is assigned to absorption of hydrogen bonding solvated molecular complex. This involves an electron transfer from the lone pair of electrons belonging to solvent molecule to the σ*-antibonding orbital of the acidic NH bond belongs to H 2DZ form.

  2. Evidence and future scenarios of a low-carbon energy transition in Central America: a case study in Nicaragua

    NASA Astrophysics Data System (ADS)

    Barido, Diego Ponce de Leon; Johnston, Josiah; Moncada, Maria V.; Callaway, Duncan; Kammen, Daniel M.

    2015-10-01

    The global carbon emissions budget over the next decades depends critically on the choices made by fast-growing emerging economies. Few studies exist, however, that develop country-specific energy system integration insights that can inform emerging economies in this decision-making process. High spatial- and temporal-resolution power system planning is central to evaluating decarbonization scenarios, but obtaining the required data and models can be cost prohibitive, especially for researchers in low, lower-middle income economies. Here, we use Nicaragua as a case study to highlight the importance of high-resolution open access data and modeling platforms to evaluate fuel-switching strategies and their resulting cost of power under realistic technology, policy, and cost scenarios (2014-2030). Our results suggest that Nicaragua could cost-effectively achieve a low-carbon grid (≥80%, based on non-large hydro renewable energy generation) by 2030 while also pursuing multiple development objectives. Regional cooperation (balancing) enables the highest wind and solar generation (18% and 3% by 2030, respectively), at the least cost (US127 MWh-1). Potentially risky resources (geothermal and hydropower) raise system costs but do not significantly hinder decarbonization. Oil price sensitivity scenarios suggest renewable energy to be a more cost-effective long-term investment than fuel oil, even under the assumption of prevailing cheap oil prices. Nicaragua’s options illustrate the opportunities and challenges of power system decarbonization for emerging economies, and the key role that open access data and modeling platforms can play in helping develop low-carbon transition pathways.

  3. Low energy cyclotron production of multivalent transition metals for PET imaging and therapy

    NASA Astrophysics Data System (ADS)

    Avila-Rodriguez, Miguel Angel

    Recent advances in high-resolution tomographs for small animals require the production of nonconventional long-lived positron emitters to label novel radiopharmaceuticals for PET-based molecular imaging. Radioisotopes with an appropriate half life to match the kinetics of slow biological processes will allow to researchers to study the phamacokinetics of PET ligands over several hours, or even days, on the same animal, with the injection of a single dose. In addition, radionuclides with a suitable half life can potentially be distributed from a central production site making them available in PET facilities that lack an in-house cyclotron. In the last few years there has been a growing interest in the use of PET ligands labeled with radiometals, particularly isotopes of copper, yttrium and zirconium. Future clinical applications of these tracers will require them to be produced reliably and efficiently. This thesis work deals with implementing and optimizing the production of the multivalent transition metals 61,64Cu, 86Y and 89Zr for molecular PET imaging and therapy. Our findings in the production of these radionuclides at high specific activity on an 11 MeV proton-only cyclotron are presented. Local applications of these tracers, including Cu-ATSM for in vivo quantification of hypoxia, synthesis of targeted radiopharmaceuticals using activated esters of DOTA, and a novel development of positron emitting resin microspheres, are also be discussed. As a result of this thesis work, metallic radionuclides are now efficiently produced on a weekly basis in sufficient quality and quantity for collaborating scientists at UW-Madison and external users in other Universities across the country.

  4. Low-energy transitions in ^112Cd identified in the beta-decays of ^112Ag and ^112In

    NASA Astrophysics Data System (ADS)

    Green, K. L.; Garrett, P. E.; Demand, G. A.; Grinyer, G. F.; Leach, K. G.; Phillips, A. A.; Schumaker, M. A.; Svensson, C. E.; Wong, J.; Ball, G. C.; Bandyopadhyay, D. S.; Hackman, G.; Morton, A. C.; Pearson, C. J.; Austin, R. A. E.; Colosimo, S.; Cross, D.; Wood, J. L.; Kulp, W. D.; Yates, S. W.

    2008-10-01

    The Cd isotopes, especially ^112Cd, have been considered exceptional examples of vibrational nuclei. While many level lifetimes are known in ^112Cd, previous measurements lacked sensitivity to weak, low-energy branches that are often the most important transitions to establish collectivity. We have sought these branches through a high-statistics measurement of the β decay of ^112Ag and ^112In to ^112Cd using the 8π spectrometer at the TRIUMF-ISAC facility. The data were collected in scaled-down γ singles and γγ coincidence mode, and ˜100x10^6 events were sorted into a random-background-subtracted γγ matrix. New branches from levels below 2.5 MeV were observed, and a higher precision on several branching ratios, especially the 4^+ and 0^+ doublet of states at 1871 keV, has been achieved. Details of the analysis to date will be reported. Work supported in part by NSERC and the US DOE under grant DE-FG02-96ER40958.

  5. Interplay between low-energy optical phonon modes and structural transition in PrT2Zn20 (T=Ru and Ir)

    NASA Astrophysics Data System (ADS)

    Wakiya, K.; Onimaru, T.; Tsutsui, S.; Matsumoto, K. T.; Nagasawa, N.; Baron, A. Q. R.; Hasegawa, T.; Ogita, N.; Udagawa, M.; Takabatake, T.

    2015-03-01

    Atomic dynamics of PrT2Zn20 for T=Ru with a structural transition at Ts=138 K and T=Ir without such a transition have been studied by inelastic X-ray scattering (IXS) measurements. The IXS spectra for T=Ru reveal an optical phonon excitation at 3 meV. We assign it to low-energy vibration of the Zn atom at the 16c site by taking account of the first principles calculation [Hasegawa et al. 2012 J. Phys.: Conf. Proc. 391 012016]. For T=Ir, on the other hand, the optical excitation at 3 meV was not observed. The contrasting results indicate that the low-energy optical phonon mode has a role in the structural transition in PrRu2Zn20 and isostructural La counterparts.

  6. Energy development: crisis and transition

    SciTech Connect

    Gordon, L.

    1981-04-01

    The historical role of energy use in economic development has not been as clear as were the roles of land, labor, and capital until recent shortages brought it into a clearer perspective. Added to this were ambiguities in the computation of the energy consumption/economic growth relationship that overstated the fuel-conversion efficiencies of developing countries. Energy differs from other raw materials in its pervasiveness, its inability to be recycled, and its low elasticity of substitution, which make it a potential constraint on economic growth. Oil-importing developing countries accumulated large balance-of-payment deficits during the 1970s in addition to drawing down their traditional energy reserves through deforestation and the use of organic wastes as fuels. The management of a long-term energy transition is more acute for developing countries, but international cooperation to keep this transition violence-free will benefit all nations. Arguments are made for a positive response to the call for a global energy strategy. (DCK)

  7. Low floor mass transit vehicle

    DOEpatents

    Emmons, J. Bruce; Blessing, Leonard J.

    2004-02-03

    A mass transit vehicle includes a frame structure that provides an efficient and economical approach to providing a low floor bus. The inventive frame includes a stiff roof panel and a stiff floor panel. A plurality of generally vertical pillars extend between the roof and floor panels. A unique bracket arrangement is disclosed for connecting the pillars to the panels. Side panels are secured to the pillars and carry the shear stresses on the frame. A unique seating assembly that can be advantageously incorporated into the vehicle taking advantage of the load distributing features of the inventive frame is also disclosed.

  8. Polarization correlations for electron-impact excitation of the resonant transitions of Ne and Ar at low incident energies

    NASA Astrophysics Data System (ADS)

    Hargreaves, L. R.; Campbell, C.; Khakoo, M. A.; McConkey, J. W.; Zatsarinny, O.; Bartschat, K.; Stauffer, A. D.; McEachran, R. P.

    2013-02-01

    The electron-polarized-photon coincidence method is used to determine linear and circular polarization correlations in vacuum ultraviolet (VUV) for the differential electron-impact excitation of neon and argon resonance transitions at impact energies of 25 and 30 eV at small scattering angles up to 40°. The circular polarization correlation is found to be positive in the case of Ne at 25 eV and supports the prediction of the present B-spline R-matrix theory concerning the violation of a long-established propensity rule regarding angular momentum transfer in electron-impact excitation of S→P transitions. Comparisons with the results from the present relativistic distorted-wave approximation and an earlier semirelativistic distorted-wave Born model are also made. For the case of Ar, at 25 and 30 eV, the circular polarization measurements remain in agreement with theory, but provide limited evidence as to whether or not the circular polarization at small scattering angles is also positive. For the linear polarizations, much better agreement with theory is obtained than in earlier measurements carried out by S. H. Zheng and K. Becker [Z. Phys. DZDACE20178-768310.1007/BF01436735 23, 137 (1992); J. Phys. BJPAMA40022-370010.1088/0953-4075/26/3/022 26, 517 (1993)].

  9. Predominance of multielectron processes contributing to the intrinsic spectra of low-energy Auger transitions in copper and gold

    SciTech Connect

    Mukherjee, S. F.; Shastry, K.; Weiss, A. H.

    2011-10-15

    Positron-annihilation-induced Auger electron spectroscopy (PAES) was used to obtain Cu and Au Auger spectra that are free of primary-beam-induced backgrounds by impinging the positrons at an energy below the secondary-electron-emission threshold. The removal of the core electron via annihilation in the PAES process resulted in the elimination of postcollision effects. The spectra indicate that there is an intense low-energy tail (LET) associated with the Auger peak that extends all the way to 0 eV. The LET is interpreted as indicative of processes in which filling of the core hole by a valence electron results in the ejection of two or more valence electrons which share the energy of the conventional core-valence-valence Auger electron.

  10. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

    SciTech Connect

    Roberts, J.G.

    2000-05-01

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

  11. European transition to a low carbon electricity system using a mix of variable renewable energies: carbon saving trajectories as functions of production and storage capacity.

    NASA Astrophysics Data System (ADS)

    Francois, Baptiste; Creutin, Jean-Dominique

    2016-04-01

    Today, most of the produced energy is generated from fossil energy sources (i.e. coal, petroleum). As a result, the energy sector is still the main source of greenhouse gas in the atmosphere. For limiting greenhouse gas emission, a transition from fossil to renewable energy is required, increasing gradually the fraction energy coming from variable renewable energy (i.e. solar power, wind power and run-of-the river hydropower, hereafter denoted as VRE). VRE penetration, i.e. the percentage of demand satisfied by variable renewables assuming no storage capacity, is hampered by their variable and un-controllable features. Many studies show that combining different VRE over space smoothes their variability and increases their global penetration by a better match of demand fluctuations. When the demand is not fully supplied by the VRE generation, backup generation is required from stored energy (mostly from dams) or fossil sources, the latter being associated with high greenhouse gas emission. Thus the VRE penetration is a direct indicator of carbon savings and basically depends on the VRE installed capacity, its mix features, and on the installed storage capacity. In this study we analyze the European transition to a low carbon electricity system. Over a selection of representative regions we analyze carbon saving trajectories as functions of VRE production and storage capacities for different scenarios mixing one to three VRE with non-renewables. We show substantial differences between trajectories when the mix of sources is far from the local optimums, when the storage capacity evolves. We bring new elements of reflection about the effect of transport grid features from local independent systems to a European "copper plate". This work is part of the FP7 project COMPLEX (Knowledge based climate mitigation systems for a low carbon economy; Project FP7-ENV-2012 number: 308601; http://www.complex.ac.uk/).

  12. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy Th229 Nuclear Isomeric Transition

    DOE PAGES

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T.; Rellergert, Wade G.; Mirzadeh, Saed; Cassanho, A.; Jenssen, H. P.; Tkalya, Eugene V.; Hudson, Eric R.

    2015-06-23

    We report the results of a direct search for the 229Tn (Iπ = 3/2+ ← 5/2+) nuclear isomeric transition, performed by exposing 229Tn-doped LiSrAlF6 crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1–2) s≲τ≲ (2000-5600) s. Lastly, this measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  13. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy (229)Th Nuclear Isomeric Transition.

    PubMed

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T; Rellergert, Wade G; Mirzadeh, Saed; Cassanho, A; Jenssen, H P; Tkalya, Eugene V; Hudson, Eric R

    2015-06-26

    We report the results of a direct search for the (229)Th (I(π)=3/2(+)←5/2(+)) nuclear isomeric transition, performed by exposing (229)Th-doped LiSrAlF(6) crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s≲τ≲(2000-5600)  s. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  14. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy (229)Th Nuclear Isomeric Transition.

    PubMed

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T; Rellergert, Wade G; Mirzadeh, Saed; Cassanho, A; Jenssen, H P; Tkalya, Eugene V; Hudson, Eric R

    2015-06-26

    We report the results of a direct search for the (229)Th (I(π)=3/2(+)←5/2(+)) nuclear isomeric transition, performed by exposing (229)Th-doped LiSrAlF(6) crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s≲τ≲(2000-5600)  s. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches. PMID:26197124

  15. Free-free transitions in the presence of laser fields and Debye potential at very low incident electron energies

    NASA Astrophysics Data System (ADS)

    Bhatia, A. K.; Sinha, C.

    2012-11-01

    Free - free transition is studied for electron - Hydrogen atom in ground state inside a plasma in presence of an external homogeneous, monochromatic and linearly polarized laser field. The effect of plasma screening is considered in the frame work of Debye Shielding approximation. The incident electron is considered to be dressed by the laser in a non perturbative manner by choosing the Volkov solutions in both the channels. The major effect of plasma screeing on the laser assisted cross scetions is to enhance the latter significantly both for the singlet and triplet transitions.

  16. Examining the low energy electrodynamics of the superconductor-insulator transition in the potential topological superconductor Tl4(Tl1-xSnx)Te3

    NASA Astrophysics Data System (ADS)

    Laurita, N. J.; Arpino, K. A.; Koopayeh, S. M.; McQueen, T. M.; Armitage, N. P.

    The search for an intrinsic single crystal topological superconductor is one of the most dynamic areas of modern condensed matter physics. One of the best candidates of such a material is Tl5Te3 (Tc = 2 . 3 K), which previous ARPES measurements have shown possesses a Dirac cone within its superconducting gap. However, the fundamental nature of superconductivity, i.e. the superconducting order parameter, in Tl5Te3 remains unknown. Additionally, it has been shown that Tl5Te3 undergoes a superconducting-insulator transition upon doping with Sn. With no band parity inversion expected in the fully Sn doped compound one expects a topological supercondutor - trivial insulator transition, the nature of which is also unknown. In this work we use highly sensitive microwave cavity perturbation measurements, a direct probe of the superfluid density, to study the low energy electrodynamics of superconductivity in Tl5Te3 and its corresponding superconductor-insulator transition upon Sn doping. Work at Johns Hopkins was supported by the Gordon and Betty Moore Foundation through Grant GBMF2628, the DOE-BES through DE-FG02-08ER46544, and the ARCS Foundation.

  17. The Effect of Disorder on the Free-Energy for the Random Walk Pinning Model: Smoothing of the Phase Transition and Low Temperature Asymptotics

    NASA Astrophysics Data System (ADS)

    Berger, Quentin; Lacoin, Hubert

    2011-01-01

    We consider the continuous time version of the Random Walk Pinning Model (RWPM), studied in (Berger and Toninelli (Electron. J. Probab., to appear) and Birkner and Sun (Ann. Inst. Henri Poincaré Probab. Stat. 46:414-441, 2010; arXiv:0912.1663). Given a fixed realization of a random walk Y on ℤ d with jump rate ρ (that plays the role of the random medium), we modify the law of a random walk X on ℤ d with jump rate 1 by reweighting the paths, giving an energy reward proportional to the intersection time Lt(X,Y)=int0t {1}_{Xs=Ys} {d}s: the weight of the path under the new measure is exp ( βL t ( X, Y)), β∈ℝ. As β increases, the system exhibits a delocalization/localization transition: there is a critical value β c , such that if β> β c the two walks stick together for almost-all Y realizations. A natural question is that of disorder relevance, that is whether the quenched and annealed systems have the same behavior. In this paper we investigate how the disorder modifies the shape of the free energy curve: (1) We prove that, in dimension d≥3, the presence of disorder makes the phase transition at least of second order. This, in dimension d≥4, contrasts with the fact that the phase transition of the annealed system is of first order. (2) In any dimension, we prove that disorder modifies the low temperature asymptotic of the free energy.

  18. The intramolecular impact to the sequence specificity of B-->A transition: low energy conformational variations in AA/TT and GG/CC steps.

    PubMed

    Il'icheva, I A; Vlasov, P K; Esipova, N G; Tumanyan, V G

    2010-04-01

    It is well known, that local B--> A transformation in DNA is involved in several biological processes. In vitro B<--> A transition is sequence-specific. The physical basis of this specificity is not known yet. Here we analyze the effect of intramolecular interactions on the structural behavior of the GG/CC and AA/TT steps. These steps exemplify sequence specific bias to the B- or A-form structure. Optimization of potential energy of the molecular systems composed of an octanucleotide, neutralized by Na(+) and solvated with TIP3P water molecules in rectangular box with periodic boundary conditions gives the statistically representative sets of low energy structures for GG/CC and AA/TT steps in the middle of the diverse flanking sequences. Permissible 3D variations of GG/CC and AA/TT, and correlation of the relative motion of base pairs in these steps were analyzed. AA/TT step permits high variability for low energy conformers in the B-form DNA and small variability for low energy conformers in the A-form DNA. In contrast GG/CC step permits high variability for low energy conformers in the A-form DNA and small variability for low energy conformers in the B-form DNA. The relative motion of base pairs in GG/CC step is high correlated, while in AA/TT step this correlation is notably less. Atom-atom interactions inside-the-step always favors the B-form and their component - stacking interactions (atom-atom interactions between nucleic bases) is crucial for the duplex stabilization. Formation of the A-form for both steps is a result of interactions with the flanking sequences and water-cation environment in the box. The average energy difference between conformations presenting B-form and A-form for the GG/CC step is high, while for the AA/TT step it is rather low. Thus, intramolecular interactions in GG/CC and AA/TT steps affect the possible conformational diversity ("conformational entropy") of the A- and B- type structures of DNA step. This determines the known bias of

  19. The Intramolecular Impact to the Sequence Specificity of B→A Transition: Low Energy Conformational Variations in AA/TT and GG/CC Steps.

    PubMed

    Il'icheva, I A; Vlasov, P K; Esipova, N G; Tumanyan, V G

    2010-04-01

    Abstract It is well known, that local B→A transformation in DNA is involved in several biological processes. In vitro B↔A transition is sequence-specific. The physical basis of this specificity is not known yet. Here we analyze the effect of intramolecular interactions on the structural behavior of the GG/CC and AA/TT steps. These steps exemplify sequence specific bias to the B- or A-form structure. Optimization of potential energy of the molecular systems composed of an octanucle-otide, neutralized by Na(+) and solvated with TIP3P water molecules in rectangular box with periodic boundary conditions gives the statistically representative sets of low energy structures for GG/CC and AA/TT steps in the middle of the diverse flanking sequences. Permissible 3D variations of GG/CC and AA/TT, and correlation of the relative motion of base pairs in these steps were analyzed. AA/TT step permits high variability for low energy conformers in the B-form DNA and small variability for low energy conformers in the A-form DNA. In contrast GG/CC step permits high variability for low energy conformers in the A-form DNA and small variability for low energy conformers in the B-form DNA. The relative motion of base pairs in GG/CC step is high correlated, while in AA/TT step this correlation is notably less. Atom-atom interactions inside-the-step always favors the B-form and their component - stacking interactions (atomatom interactions between nucleic bases) is crucial for the duplex stabilization. Formation of the A-form for both steps is a result of interactions with the flanking sequences and water-cation environment in the box. The average energy difference between conformations presenting B-form and A-form for the GG/CC step is high, while for the AA/TT step it is rather low. Thus, intramolecular interactions in GG/CC and AA/TT steps affect the possible conformational diversity ("conformational entropy") of the A- and B- type structures of DNA step. This determines the known

  20. Cold moving mice: A microfoil internal conversion electron detector for low and intermediate energy Mössbauer transitions

    NASA Astrophysics Data System (ADS)

    Mullen, James G.; Djedid, Ammar; Holmes, Clifford; Schupp, Guy; Crow, Lowell; Yelon, William

    1986-03-01

    A microfoil internal conversion electron (MICE) detector is described which permits direct Doppler shifting of resonance radiation up to velocities of ± 20 cm/s, and gives large improvements in signal-to-background ratios for many Mössbauer isotopes, when compared with transmission geometry. The detector described has efficiency of nearly unity, and it allows for cooling the reciprocating microfoil module to 100 K, which improves signal-to-background substantially over room temperature operation. We give an analysis of the signal-to-background that can be expected for this MICE detector, and for a corresponding transmission experiment. In a table of neutron produced isotopes we find more than 10 cases which are favorable to the MICE approach as compared with the more conventional transmission geometry. The signal-to-background enhancement predicted for several Mössbauer isotopes is substantial for the MICE geometry compared to transmission geometry. Direct measurements of the Mössbauer conversion electron spectrum for the 46.5 and 99.1 keV transitions of 183W and the 100.1 keV transition in 182W are reported and compared with our analysis. In the case of 183W (46.5 keV) we observe over 500% signal-to-background, and this experimental result agrees well with our analysis of the expected size of the effect. Satisfactory agreement is also found for the 99.1 keV 183W and 100.1 keV 182W spectra. Based on the analysis given it is possible to determine nuclear resonance cross sections and thereby infer internal conversion coefficients for the resonance transitions. Thus, we are able to determine the internal conversion coefficient for the 46.5 keV transition in 183W to be α = 13 ± 3.

  1. Free-Free Transitions of the e-H System Inside a Dense Plasma Irradiated by a Laser Field at Very Low Incident-Electron Energies

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Sinha, C.

    2012-01-01

    The free-free transition is studied for an electron-hydrogen atom in ground state when a low-energy electron (external) is injected into hydrogenic plasma in the presence of an external homogenous, monochromatic, and linearly polarized laser field. The effect of plasma screening is considered in the Debye-Huckel approximation. The calculations are performed in the soft photon limit. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing the Volkov solutions in both the initial and final channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the electron exchange. The laser-assisted differential and total cross sections are calculated for single-photon absorption or emission and no-photon exchange in the soft photon limit, the laser intensity being much less than the atomic field intensity. The calculations have been carried out for various values of Debye parameter, ranging from 0.005 to 0.12. A strong suppression is noted in the laser-assisted cross sections as compared to the field-free situation. A significant difference is noted for the singlet and triplet cross sections. The suppression is much more in the triplet states.

  2. Free-free transitions of the e-H system inside a dense plasma irradiated by a laser field at very low incident-electron energies

    NASA Astrophysics Data System (ADS)

    Bhatia, A. K.; Sinha, C.

    2012-11-01

    The free-free transition is studied for an electron-hydrogen atom in ground state when a low-energy electron (external) is injected into hydrogenic plasma in the presence of an external homogenous, monochromatic, and linearly polarized laser field. The effect of plasma screening is considered in the Debye-Hückel approximation. The calculations are performed in the soft photon limit. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing the Volkov solutions in both the initial and final channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the electron exchange. The laser-assisted differential and total cross sections are calculated for single-photon absorption or emission and no-photon exchange in the soft photon limit, the laser intensity being much less than the atomic field intensity. The calculations have been carried out for various values of Debye parameter, ranging from 0.005 to 0.12. A strong suppression is noted in the laser-assisted cross sections as compared to the field-free situation. A significant difference is noted for the singlet and triplet cross sections. The suppression is much more in the triplet states.

  3. Free-Free Transitions of e-H System Inside a Dense Plasma Irradiated by a Laser Field at Very Low Incident Electron Energies

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Sinha, C.

    2012-01-01

    The free-free transition is studied for an electron-hydrogen in the ground state at low incident energies in the presence of an external homogenous, monochromatic, and linearly polarized laser-field inside a hot dense plasma.The effect of plasma screening is considered in the Debye-Huckel approximation. The calculations are performed in the soft photon limit, assuming that the plasma frequency is much higher than the laser frequency. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing the Volkov solutions in both the initial and final channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the electron exchange. The laser-assisted differential and total cross sections are calculated for single-photon absorption /emission and no photon exchange in the soft photon limit, the laser intensity being much less than the atomic field intensity. The calculations have been carried out for various values of Debye parameter, ranging from 0.005 to 0.12. A strong suppression is noted in the laser-assisted cross sections as compared to the field-free situation. A significant difference is noted for the singlet and triplet cross sections. The suppression is much more in the triplet states.

  4. Energy Transition Initiative: Islands Playbook (Book)

    SciTech Connect

    Not Available

    2015-01-01

    The Island Energy Playbook (the Playbook) provides an action-oriented guide to successfully initiating, planning, and completing a transition to an energy system that primarily relies on local resources to eliminate a dependence on one or two imported fuels. It is intended to serve as a readily available framework that any community can adapt to organize its own energy transition effort.

  5. An Institutional Approach to Understanding Energy Transitions

    NASA Astrophysics Data System (ADS)

    Koster, Auriane Magdalena

    Energy is a central concern of sustainability because how we produce and consume energy affects society, economy, and the environment. Sustainability scientists are interested in energy transitions away from fossil fuels because they are nonrenewable, increasingly expensive, have adverse health effects, and may be the main driver of climate change. They see an opportunity for developing countries to avoid the negative consequences fossil-fuel-based energy systems, and also to increase resilience, by leap-frogging-over the centralized energy grid systems that dominate the developed world. Energy transitions pose both challenges and opportunities. Obstacles to transitions include 1) an existing, centralized, complex energy-grid system, whose function is invisible to most users, 2) coordination and collective-action problems that are path dependent, and 3) difficulty in scaling up RE technologies. Because energy transitions rely on technological and social innovations, I am interested in how institutional factors can be leveraged to surmount these obstacles. The overarching question that underlies my research is: What constellation of institutional, biophysical, and social factors are essential for an energy transition? My objective is to derive a set of "design principles," that I term institutional drivers, for energy transitions analogous to Ostrom's institutional design principles. My dissertation research will analyze energy transitions using two approaches: applying the Institutional Analysis and Development Framework and a comparative case study analysis comprised of both primary and secondary sources. This dissertation includes: 1) an analysis of the world's energy portfolio; 2) a case study analysis of five countries; 3) a description of the institutional factors likely to promote a transition to renewable-energy use; and 4) an in-depth case study of Thailand's progress in replacing nonrenewable energy sources with renewable energy sources. My research will

  6. Low Energy Supersymmetry Phenomenology

    SciTech Connect

    Feng, J.

    2003-06-16

    We summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, we evaluate the capabilities of various e{sup +}e{sup -}, p{bar p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, we discuss capabilities of future facilities to dis-entangle the anticipated spectrum of super-particles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. We comment upon the complementarity of proposed hadron and e{sup +}e{sup -} machines for a comprehensive study of low energy supersymmetry.

  7. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.; Feng, J.; Fujii, K.; Gunion, J.; Kamon, T.; Lopez, J.L.; Kao, C.

    1995-04-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{bar p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of super-particles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. The authors then comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  8. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.

    1995-03-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{anti p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of superparticles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. They comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  9. Low-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Ludhova, Livia

    2016-05-01

    There exist several kinds of sources emitting neutrinos in the MeV energy range. These low-energy neutrinos from different sources can be often detected by the same multipurpose detectors. The status-of-art of the field of solar neutrinos, geoneutrinos, and the search for sterile neutrino with artificial neutrino sources is provided here; other neutrino sources, as for example reactor or high-energy neutrinos, are described elsewhere. For each of these three fields, the present-day motivation and open questions, as well as the latest experimental results and future perspectives are discussed.

  10. X-Ray Transition Energies Database

    National Institute of Standards and Technology Data Gateway

    SRD 128 X-Ray Transition Energies Database (Web, free access)   This X-ray transition table provides the energies and wavelengths for the K and L transitions connecting energy levels having principal quantum numbers n = 1, 2, 3, and 4. The elements covered include Z = 10, neon to Z = 100, fermium. There are two unique features of this data base: (1) a serious attempt to have all experimental values on a scale consistent with the International System of measurement (the SI) and (2) inclusion of accurate theoretical estimates for all transitions.

  11. Energy implications of fixed rail mass transit

    SciTech Connect

    Pikarsky, M.

    1981-01-01

    Major studies on whether mass transit actually saves energy are reviewed. A possible petroleum conservation strategy that focusses on future urban and regional development is then identified. A number of U.S. cities are considered to be prime candidates for rail transit systems for the purpose of energy conservation. 30 refs.

  12. LOW ENERGY COUNTING CHAMBERS

    DOEpatents

    Hayes, P.M.

    1960-02-16

    A beta particle counter adapted to use an end window made of polyethylene terephthalate was designed. The extreme thinness of the film results in a correspondingly high transmission of incident low-energy beta particles by the window. As a consequence, the counting efficiency of the present counter is over 40% greater than counters using conventional mica end windows.

  13. Transit station energy impacts. Research report (Interim)

    SciTech Connect

    Coleman, P.; Euritt, M.; Walton, C.M.

    1992-12-01

    Transit trips-when compared with automobile travel-not only relieve congestion, but also offer considerable energy savings per person. Transit trips also affect land use and development patterns that surround a transit station. In the report, a methodology will be developed to estimate the energy savings associated with land use changes in the station areas. Since changes in land use and development in a station area are partially dependent on the type of service offered (rail versus bus rapid, for example), a classification system will be developed for different types of transit stations, a system based on the land use and development changes that occur within the station's zone of influence.

  14. Energy Released During the H-L Back Transition

    NASA Astrophysics Data System (ADS)

    Eldon, D.; Kolemen, E.; Gohil, P.; McKee, G. R.; Yan, Z.; Schmitz, L.

    2015-11-01

    Prompt energy loss (ΔW) at the H-L transition, as a fraction of total stored energy before the transition, is about 30 % and is insensitive to density in ITER-similar DIII-D plasmas. Occasionally, some ELMs will appear before the transition and reduce total energy, thus reducing ΔW across the following transition. Other results (not in the ITER-similar shape) have shown that ELMs can be triggered in low powered H-modes, prior to H-L transitions, when the plasma is stable to ideal P-B modes (these are not typical type-I ELMs, despite superficial similarities) and E × B shear is strong. These are indeed ELMs occurring in H-mode and not part of a dithering transition. Finally, ELM ΔW is sensitive to edge toroidal rotation and becomes smaller than uncertainty (< 5 kJ) at low rotation (ωtor < 5 krad/s). These results point to a strategy where ΔW for the H-L transition may be reduced by the presence of (not type-I) ELMs before the transition, and ΔW for the ELMs may be reduced by controlling rotation. Work supported by the US Department of Energy under DE-AC02-09CH11466 and DE-FC02-04ER54698.

  15. Distribution of glass transition temperatures Tg in polystyrene thin films as revealed by low-energy muon spin relaxation: A comparison with neutron reflectivity results.

    PubMed

    Kanaya, Toshiji; Ogawa, Hiroki; Kishimoto, Mizuki; Inoue, Rintaro; Suter, Andreas; Prokscha, Thomas

    2015-08-01

    In a previous paper [Phys. Rev. E 83, 021801 (2011)] we performed neutron reflectivity (NR) measurements on a five-layer polystyrene (PS) thin film consisting of alternatively stacked deuterated polystyrene (dPS) and hydrogenated polystyrene (hPS) layers (dPS/hPS/dPS/hPS/dPS, ∼100 nm thick) on a Si substrate to reveal the distribution of Tg along the depth direction. Information on the Tg distribution is very useful to understand the interesting but unusual properties of polymer thin films. However, one problem that we have to clarify is if there are effects of deuterium labeling on Tg or not. To tackle the problem we performed low-energy muon spin relaxation (μSR) measurements on the above-mentioned deuterium-labeled five-layer PS thin film as well as dPS and hPS single-layer thin films ∼100 nm thick as a function of muon implantation energy. It was found that the deuterium labeling had no significant effects on the Tg distribution, guaranteeing that we can safely discuss the unusual thin film properties based on the Tg distribution revealed by NR on the deuterium-labeled thin films. In addition, the μSR result suggested that the higher Tg near the Si substrate is due to the strong orientation of phenyl rings. PMID:26382423

  16. Distribution of glass transition temperatures Tg in polystyrene thin films as revealed by low-energy muon spin relaxation: A comparison with neutron reflectivity results

    NASA Astrophysics Data System (ADS)

    Kanaya, Toshiji; Ogawa, Hiroki; Kishimoto, Mizuki; Inoue, Rintaro; Suter, Andreas; Prokscha, Thomas

    2015-08-01

    In a previous paper [Phys. Rev. E 83, 021801 (2011), 10.1103/PhysRevE.83.021801] we performed neutron reflectivity (NR) measurements on a five-layer polystyrene (PS) thin film consisting of alternatively stacked deuterated polystyrene (dPS) and hydrogenated polystyrene (hPS) layers (dPS/hPS/dPS/hPS/dPS, ˜100 nm thick) on a Si substrate to reveal the distribution of Tg along the depth direction. Information on the Tg distribution is very useful to understand the interesting but unusual properties of polymer thin films. However, one problem that we have to clarify is if there are effects of deuterium labeling on Tg or not. To tackle the problem we performed low-energy muon spin relaxation (μ SR ) measurements on the above-mentioned deuterium-labeled five-layer PS thin film as well as dPS and hPS single-layer thin films ˜100 nm thick as a function of muon implantation energy. It was found that the deuterium labeling had no significant effects on the Tg distribution, guaranteeing that we can safely discuss the unusual thin film properties based on the Tg distribution revealed by NR on the deuterium-labeled thin films. In addition, the μ SR result suggested that the higher Tg near the Si substrate is due to the strong orientation of phenyl rings.

  17. Distribution of glass transition temperatures Tg in polystyrene thin films as revealed by low-energy muon spin relaxation: A comparison with neutron reflectivity results.

    PubMed

    Kanaya, Toshiji; Ogawa, Hiroki; Kishimoto, Mizuki; Inoue, Rintaro; Suter, Andreas; Prokscha, Thomas

    2015-08-01

    In a previous paper [Phys. Rev. E 83, 021801 (2011)] we performed neutron reflectivity (NR) measurements on a five-layer polystyrene (PS) thin film consisting of alternatively stacked deuterated polystyrene (dPS) and hydrogenated polystyrene (hPS) layers (dPS/hPS/dPS/hPS/dPS, ∼100 nm thick) on a Si substrate to reveal the distribution of Tg along the depth direction. Information on the Tg distribution is very useful to understand the interesting but unusual properties of polymer thin films. However, one problem that we have to clarify is if there are effects of deuterium labeling on Tg or not. To tackle the problem we performed low-energy muon spin relaxation (μSR) measurements on the above-mentioned deuterium-labeled five-layer PS thin film as well as dPS and hPS single-layer thin films ∼100 nm thick as a function of muon implantation energy. It was found that the deuterium labeling had no significant effects on the Tg distribution, guaranteeing that we can safely discuss the unusual thin film properties based on the Tg distribution revealed by NR on the deuterium-labeled thin films. In addition, the μSR result suggested that the higher Tg near the Si substrate is due to the strong orientation of phenyl rings.

  18. Hopping energy and percolation-type transport in p-GaAs low densities near the 2D metal-insulator transition at zero magnetic field

    NASA Astrophysics Data System (ADS)

    Dlimi, S.; El kaaouachi, A.; Narjis, A.; Limouny, L.; Sybous, A.; Errai, M.

    2013-10-01

    We investigated the temperature dependence of resistivity of a high mobility two-dimensional holes system grown on the (311) GaAs surface in the absence of the magnetic field near the metal-insulator transition. The Coulomb hopping was found in a wide range of temperature and carrier density. Quantitative analysis of our results suggests that a crossover from Efros-Shklovskii to Mott variable range hopping due to screening phenomenon when the hopping distance increases. We found that using the 2D single particle hopping amplitude CES gives unreasonably high localization lengths. Therefore, we believe that electrical transport is dominated by correlated hopping and the hopping amplitude must be renormalized by a reduction factor A≈1.6. The localization length appears to diverge in a power-law fashion near the transition point. The analysis of the hopping gives results consistent with the prediction of the critical point from a recent study of percolation and other experiences.

  19. Theory of low transitions in CO discharge lasers

    NASA Technical Reports Server (NTRS)

    Sidney, B. D.; Mcinuille, R. M.; Smith, N. S.; Hassan, H. A.

    1976-01-01

    A self consistent theoretical model which couples the electron and heavy particle finite rate kinetics with the optical and fluid dynamic processes has been employed to identify the various parameters and explain the mechanism responsible for producing low lying transitions in slow flowing CO lasers. It is found that lasing on low lying transitions can be achieved at low temperatures for low pressures (or low flow rates) together with high partial pressures of the He and N2. The role of N2 has been identified as an additive responsible for reducing the electron temperature to a range where the transfer of electrical power to the lower vibrational modes of CO is optimum.

  20. Aspects of energy transitions: History and determinants

    NASA Astrophysics Data System (ADS)

    O'Connor, Peter A.

    Energy intensity in the U.S. from 1780 to 2010 shows a declining trend when traditional energy is included, in contrast to the "inverted U-curve" seen when only commercial energy is considered. The analysis quantifies use of human and animal muscle power, wind and water power, biomass, harvested ice, fossil fuels, and nuclear power. Historical prices are provided for many energy resources. The analysis reaffirms the importance of innovation in conversion technologies in energy transitions. An increase in energy intensity in the early 20th century is explained by diminishing returns to pre-electric manufacturing systems, which produced a transformation in manufacturing. In comparison to similar studies for other countries, the U.S. has generally higher energy intensity. A population-weighted series of heating degree days and cooling degree days partially explains differences in energy intensity. Series are developed for 231 countries and territories with multiple reference temperatures, with a "wet-bulb" series accounting for the effects of humidity. Other variables considered include energy prices, income per capita, and governance indices. A panel regression of thirty-two countries from 1995 to 2010 establishes GDP per capita and share of primary energy as determinants of energy intensity, but fails to establish statistical significance of the climate variables. A group mean regression finds average heating and cooling degree days to be significant predictors of average energy intensity over the study period, increasing energy intensity by roughly 1.5 kJ per 2005 international dollar for each annual degree day. Group mean regression results explain differences in countries' average energy intensity, but not changes within a country over time. Energy Return on Investment (EROI) influences the economic competitiveness and environmental impacts of an energy resource and is one driver of energy transitions. The EROI of U.S. petroleum production has declined since 1972

  1. Energy from low temperature differences

    NASA Astrophysics Data System (ADS)

    Parsons, B. K.

    1985-05-01

    A number of energy conservation and alternative energy approaches utilize a low temperature heat source. Applications in this category include: solar ponds, ocean thermal energy conversion (OTEC), low temperature solar thermal, geothermal, and waste heat recovery and bottoming cycles. Low temperature power extraction techniques are presented and the differences between closed and open Rankine power cycles are discussed. Specific applications and technical areas of current research in OTEC along with a breakdown of plant operating conditions and a rough cost estimate illustrate how the use of low temperature power conversion technology can be cost effective.

  2. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low-energy electron diffraction

    NASA Astrophysics Data System (ADS)

    Roberts, Joel Glenn

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2 (0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface. The surface layer of NaCl(100) was found to have a 0.12 +/- 0.03 A corrugation due to movement of the Na+ ions towards the bulk. Additional deviations from the bulk structure were not seen in the deeper atomic layers. In order to determine if the metal substrate had an influence on the films' growth characteristics, multilayer films of NaCl(100) were grown on Pd(100) and Pt(111). An tensor LEED (TLEED) analysis of the diffraction beam intensities from the NaCl(100)-(1 x 1) on Pd(100) and NaCl(100)-(1 x 1) on Pt(111) LEED patterns showed that the multilayer NaCl(100) film had the same structure on both substrates to a depth sampled by the electrons in the individual experimental energy ranges. Additionally, these two films exhibited the same adsorbate-substrate interaction on Pd(100) and Pt(111) as evidenced by the lone multilayer (zero order) desorption peak observed in the temperature programmed desorption (TPD) spectra of NaCl. The surface structure of LiF(100) was studied to correlate the surface corrugation of the alkali halide (100) surface to the ions' polarizability. The LiF surface is less polarizable than the NaCl surface. TLEED calculations determined that the LiF(100) surface had a 0.24 +/- 0.04 A corrugation with a 0.06 +/- 0.04 A corrugation of the second layer. Both corrugations were due to the cations moving deeper into the bulk. Unlike NaCl and LiF, MgCl2 adsorbed on Pd(111) and Pt

  3. Evaluation of jojoba oil as a low-energy fat. 2. Intestinal transit time, stomach emptying and digestibility in short-term feeding studies in rats.

    PubMed

    Verschuren, P M; Nugteren, D H

    1989-01-01

    The influence of jojoba oil (JO) incorporation in the diet on stomach emptying and intestinal transit time, and the digestion and absorption of JO were investigated in short-term feeding studies in rats. The animals were fed purified diets containing 18% (w/w) fat, of which half consisted of a mixture of lard and sunflower seed oil (SF) supplemented with an equivalent amount of JO. The control animals were fed a mixture of lard and SF (18%). No treatment-related differences were observed in the rate of stomach emptying or the intestinal transit time. Comparative lipid analysis of lymph, intestinal content, intestinal mucosa and faeces indicated that most of the ingested JO was degraded and absorbed. Part of the JO was present as wax ester in the lymph. Hydrolysis of JO was much slower than that of triacylglycerols and continued in the alimentary tract beyond the small intestine due to bacterial processes. JO did not influence the absorption of the conventional fat.

  4. A transitioning universe with anisotropic dark energy

    NASA Astrophysics Data System (ADS)

    Yadav, Anil Kumar

    2016-08-01

    In this paper, we present a model of transitioning universe with minimal interaction between perfect fluid and anisotropic dark energy in Bianchi I space-time. The two sources are assumed to minimally interacted and therefore their energy momentum tensors are conserved separately. The explicit expression for average scale factor are considered in hybrid form that gives time varying deceleration parameter which describes both the early and late time physical features of universe. We also discuss the physical and geometrical properties of the model derived in this paper. The solution is interesting physically as it explain accelerating universe as well as singularity free universe.

  5. A low energy electron magnetometer

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M., Jr.; Rayborn, G. H.; White, F. A.

    1979-01-01

    The concept of a highly sensitive magnetometer based on the deflection of low energy electron beams in magnetic fields is analyzed. Because of its extremely low mass and consequently high e/m ratio, a low energy electron is easily deflected in a magnetic field, thus providing a basis for very low field measurement. Calculations for a specific instrument design indicate that a low energy electron magnetometer (LEEM) can measure magnetic fields as low as 1000 nT. The anticipated performance of LEEM is compared with that of the existing high resolution magnetometers in selected applications. The fast response time of LEEM makes it especially attractive as a potential instrument for magnetic signature analysis in large engineering systems.

  6. RHIC low energy tests and initial operations

    SciTech Connect

    Satogata,T.; Ahrens, L.; Bai, M.; Brennan, J.M.; Bruno, D.; Butler, J.; Drees, A.; Fedotov, A.; Fischer, W.; Harvey, M.; Hayes, T.; Jappe, W.; Lee, R.C.; Mackay, W.W.; Malitsky, N.; Marr, G.; Michnoff, R.; Oerter, B.; Pozdeyev, E.; Roser, T.; Severino, F.; Smith, K.; Tepikian, S.; Tsoupas, N.

    2009-05-04

    Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by a search for the QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy of {radical} s = 20.8 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with some of these challenges during beam tests with gold in March 2008, including first RHIC operations at {radical}s = 9.18 GeV/n and first beam experience at {radical}s = 5 GeV/n.

  7. Application of a transitional boundary-layer theory in the low hypersonic Mach number regime

    NASA Technical Reports Server (NTRS)

    Shamroth, S. J.; Mcdonald, H.

    1975-01-01

    An investigation is made to assess the capability of a finite-difference boundary-layer procedure to predict the mean profile development across a transition from laminar to turbulent flow in the low hypersonic Mach-number regime. The boundary-layer procedure uses an integral form of the turbulence kinetic-energy equation to govern the development of the Reynolds apparent shear stress. The present investigation shows the ability of this procedure to predict Stanton number, velocity profiles, and density profiles through the transition region and, in addition, to predict the effect of wall cooling and Mach number on transition Reynolds number. The contribution of the pressure-dilatation term to the energy balance is examined and it is suggested that transition can be initiated by the direct absorption of acoustic energy even if only a small amount (1 per cent) of the incident acoustic energy is absorbed.

  8. Low Energy Schools in Ireland

    ERIC Educational Resources Information Center

    Heffernan, Martin

    2004-01-01

    Out of a commitment to reducing carbon dioxide emissions, Ireland's Department of Education and Science has designed and constructed two low energy schools, in Tullamore, County Offaly, and Raheen, County Laois. With energy use in buildings responsible for approximately 55% of the CO[subscript 2] released into the atmosphere and a major…

  9. Phase transition of carbonate solvent mixture solutions at low temperatures

    NASA Astrophysics Data System (ADS)

    Okumura, Takefumi; Horiba, Tatsuo

    2016-01-01

    The phase transition of carbonate solvent mixture solutions consisting of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and LiPF6 salt have been studied for improving the low temperature performance of lithium-ion batteries. The Li ion conductivity at 25 °C was maximum at x = 0.3 in a series of 1 M LiPF6 mixed carbonate solvents compositions consisting of ECxDMC0.5-0.5xEMC0.5-0.5x (x = 0 to 0.6), while the maximum tended to shift to x = 0.2 as the temperature lowered. The differential scanning calorimetry results showed that the freezing temperature depressions of EC in the 1 M LiPF6 solution were larger than those of the DMC or EMC. The chemical shift of 7Li nuclear magnetic resonance changed from a constant to increasing at around x = 0.3, which could be reasonably understood by focusing on the change in solvation energy calculated using Born equation. However, in the region of a high EC concentration of over x = 0.3 (EC/LiPF6 > 4) in the 1 M LiPF6 solution, the free EC from the solvation to the lithium ions seems to reduce the freezing temperature depression of the EC, and thus, decreases the ionic conductivity of the solution at low temperatures, due to the EC freezing.

  10. Assessment of a transitional boundary layer theory at low hypersonic Mach numbers

    NASA Technical Reports Server (NTRS)

    Shamroth, S. J.; Mcdonald, H.

    1972-01-01

    An investigation was carried out to assess the accuracy of a transitional boundary layer theory in the low hypersonic Mach number regime. The theory is based upon the simultaneous numerical solution of the boundary layer partial differential equations for the mean motion and an integral form of the turbulence kinetic energy equation which controls the magnitude and development of the Reynolds stress. Comparisions with experimental data show the theory is capable of accurately predicting heat transfer and velocity profiles through the transitional regime and correctly predicts the effects of Mach number and wall cooling on transition Reynolds number. The procedure shows promise of predicting the initiation of transition for given free stream disturbance levels. The effects on transition predictions of the pressure dilitation term and of direct absorption of acoustic energy by the boundary layer were evaluated.

  11. Density Functional Theory in Transition-Metal Chemistry: Relative Energies of Low-Lying States of Iron Compounds and the Effect of Spatial Symmetry Breaking

    SciTech Connect

    Sorkin, Anastassia; Iron, Mark A.; Truhlar, Donald G.

    2008-02-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The ground and lower excited states of Fe2, Fe2 -, and FeO+ were studied using a number of density functional theory (DFT) methods. Specific attention was paid to the relative state energies, the internuclear distances (re), and the harmonic vibrational frequencies (öe). A number of factors influencing the calculated values of these properties were examined. These include basis sets, the nature of the density functional chosen, the percentage of Hartree- Fock exchange in the density functional, and constraints on orbital symmetry. A number of different types of generalized gradient approximation (GGA) density functionals (straight GGA, hybrid GGA, meta-GGA, and hybrid meta-GGA) were examined, and it was found that the best results were obtained with hybrid GGA or hybrid meta-GGA functionals that contain nonzero fractions of HF exchange; specifically, the best overall results were obtained with B3LYP, M05, and M06, closely followed by B1LYP. One significant observation was the effect of enforcing symmetry on the orbitals. When a degenerate orbital (ð or ä) is partially occupied in the 4¼ excited state of FeO+, reducing the enforced symmetry (from C6v to C4v to C2v) results in a lower energy since these degenerate orbitals are split in the lower symmetries. The results obtained were compared to higher level ab initio results from the literature and to recent PBE+U plane wave results by Kulik et al. (Phys. Rev. Lett. 2006, 97, 103001). It was found that some of the improvements that were afforded by the semiempirical +U correction can also be accomplished by improving the form of the DFT functional and, in one case, by not enforcing high symmetry on the orbitals.

  12. The low energy signaling network

    PubMed Central

    Tomé, Filipa; Nägele, Thomas; Adamo, Mattia; Garg, Abhroop; Marco-llorca, Carles; Nukarinen, Ella; Pedrotti, Lorenzo; Peviani, Alessia; Simeunovic, Andrea; Tatkiewicz, Anna; Tomar, Monika; Gamm, Magdalena

    2014-01-01

    Stress impacts negatively on plant growth and crop productivity, caicultural production worldwide. Throughout their life, plants are often confronted with multiple types of stress that affect overall cellular energy status and activate energy-saving responses. The resulting low energy syndrome (LES) includes transcriptional, translational, and metabolic reprogramming and is essential for stress adaptation. The conserved kinases sucrose-non-fermenting-1-related protein kinase-1 (SnRK1) and target of rapamycin (TOR) play central roles in the regulation of LES in response to stress conditions, affecting cellular processes and leading to growth arrest and metabolic reprogramming. We review the current understanding of how TOR and SnRK1 are involved in regulating the response of plants to low energy conditions. The central role in the regulation of cellular processes, the reprogramming of metabolism, and the phenotypic consequences of these two kinases will be discussed in light of current knowledge and potential future developments. PMID:25101105

  13. The low energy signaling network.

    PubMed

    Tomé, Filipa; Nägele, Thomas; Adamo, Mattia; Garg, Abhroop; Marco-Llorca, Carles; Nukarinen, Ella; Pedrotti, Lorenzo; Peviani, Alessia; Simeunovic, Andrea; Tatkiewicz, Anna; Tomar, Monika; Gamm, Magdalena

    2014-01-01

    Stress impacts negatively on plant growth and crop productivity, caicultural production worldwide. Throughout their life, plants are often confronted with multiple types of stress that affect overall cellular energy status and activate energy-saving responses. The resulting low energy syndrome (LES) includes transcriptional, translational, and metabolic reprogramming and is essential for stress adaptation. The conserved kinases sucrose-non-fermenting-1-related protein kinase-1 (SnRK1) and target of rapamycin (TOR) play central roles in the regulation of LES in response to stress conditions, affecting cellular processes and leading to growth arrest and metabolic reprogramming. We review the current understanding of how TOR and SnRK1 are involved in regulating the response of plants to low energy conditions. The central role in the regulation of cellular processes, the reprogramming of metabolism, and the phenotypic consequences of these two kinases will be discussed in light of current knowledge and potential future developments.

  14. Multiple phase transitions in rare earth tetraborides at low temperature

    NASA Astrophysics Data System (ADS)

    Fisk, Z.; Maple, M. B.; Johnston, D. C.; Woolf, L. D.

    1981-09-01

    We report the temperature dependence of the magnetic susceptibility of single crystals of PrB 4, GdB 4, TbB 4, HoB 4 and TmB 4, both parallel and perpendicular to the tetragonal c-axis. We also present low temperature resistance measurements on crytals of GdB 4 through TmB 4. Two magnetic phase transitions are found for TbB 4, DyB 4, HoB 4 and TmB 4. For the latter two compounds, the lower transitions appear to be first order. For HoB 4, we have measured the low temperature specific heat. The lower transition in TbB 4 and HoB 4 is rapidly depressed upon dilution with YB 4.

  15. The Low Energy Neutrino Factory

    SciTech Connect

    Bross, Alan; Geer, Steve; Ellis, Malcolm; Fernandez Martinez, Enrique; Li, Tracey; Pascoli, Silvia; Mena, Olga

    2010-03-30

    We show that a low energy neutrino factory with a baseline of 1300 km and muon energy of 4.5 GeV has an excellent physics reach. The results of our optimisation studies demonstrate that such a setup can have remarkable sensitivity to theta{sub 13} and delta for sin{sup 2}(2theta{sub 13})>10{sup -4}, and to the mass hierarchy for sin{sup 2}(2theta{sub 13})>10{sup -3}. We also illustrate the power of the unique combination of golden and platinum channels accessible to the low energy neutrino factory. We have considered both a 20 kton totally active scintillating detector and a 100 kton liquid argon detector as possible detector technologies, finding that a liquid argon detector with very good background rejection can produce sensitivity to theta{sub 13} and delta with that of the International Design Study neutrino factory.

  16. Excitonic polarons in low-dimensional transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Thilagam, A.

    2015-05-01

    We examine the excitonic polaron properties of common monolayer transition metal dichalcogenides (MoS2, MoSe2, WS2 and WSe2). The excitonic polaron is formed when excitons interact with acoustic or optical phonons via coupling to the deformation potentials associated with the conduction and valence bands. A unitary transformation which performs an approximate diagonalization of the exciton-phonon operator is used to evaluate the ground state energy of the excitonic polaron. We derive analytical expressions of the changes in the excitonic polaron energy and mass at small exciton wavevectors involving the deformation potential due to optical phonons. The polaronic effect of the monolayer transition metal dichalcogenides is examined by comparing changes in the energy gap shift and effective masses based on known deformation potential constants for carrier-phonon interactions. Our results indicate the occurrence of comparable energy shifts when the ground state exciton interacts with optical or acoustic phonons. We extend our calculations to explore the influence of exciton-lattice interactions on the binding energies and the self-trapping of excitons in two-dimensional layers of transition metal dichalcogenides.

  17. Carbon budgets and energy transition pathways

    NASA Astrophysics Data System (ADS)

    van Vuuren, Detlef P.; van Soest, Heleen; Riahi, Keywan; Clarke, Leon; Krey, Volker; Kriegler, Elmar; Rogelj, Joeri; Schaeffer, Michiel; Tavoni, Massimo

    2016-07-01

    Scenarios from integrated assessment models can provide insights into how carbon budgets relate to other policy-relevant indicators by including information on how fast and by how much emissions can be reduced. Such indicators include the peak year of global emissions, the decarbonisation rate and the deployment of low-carbon technology. Here, we show typical values for these indicators for different carbon budgets, using the recently compiled IPCC scenario database, and discuss how these vary as a function of non-CO2 forcing, energy use and policy delay. For carbon budgets of 2000 GtCO2 and less over the 2010–2100 period, supply of low carbon technologies needs to be scaled up massively from today’s levels, unless energy use is relatively low. For the subgroup of scenarios with a budget below 1000 GtCO2 (consistent with >66% chance of limiting global warming to below 2 °C relative to preindustrial levels), the 2050 contribution of low-carbon technologies is generally around 50%–75%, compared to less than 20% today (range refers to the 10–90th interval of available data).

  18. Carbon budgets and energy transition pathways

    NASA Astrophysics Data System (ADS)

    van Vuuren, Detlef P.; van Soest, Heleen; Riahi, Keywan; Clarke, Leon; Krey, Volker; Kriegler, Elmar; Rogelj, Joeri; Schaeffer, Michiel; Tavoni, Massimo

    2016-07-01

    Scenarios from integrated assessment models can provide insights into how carbon budgets relate to other policy-relevant indicators by including information on how fast and by how much emissions can be reduced. Such indicators include the peak year of global emissions, the decarbonisation rate and the deployment of low-carbon technology. Here, we show typical values for these indicators for different carbon budgets, using the recently compiled IPCC scenario database, and discuss how these vary as a function of non-CO2 forcing, energy use and policy delay. For carbon budgets of 2000 GtCO2 and less over the 2010-2100 period, supply of low carbon technologies needs to be scaled up massively from today’s levels, unless energy use is relatively low. For the subgroup of scenarios with a budget below 1000 GtCO2 (consistent with >66% chance of limiting global warming to below 2 °C relative to preindustrial levels), the 2050 contribution of low-carbon technologies is generally around 50%-75%, compared to less than 20% today (range refers to the 10-90th interval of available data).

  19. Low-Energy Proton Testing Methodology

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Marshall, Paul W.; Heidel, David F.; Schwank, James R.; Shaneyfelt, Marty R.; Xapsos, M.A.; Ladbury, Raymond L.; LaBel, Kenneth A.; Berg, Melanie; Kim, Hak S.; Phan, Anthony; Friendlich, M.R.; Rodbell, Kenneth P.; Hakey, Mark C.; Dodd, Paul E.; Reed, Robert A.; Weller, Robert A.; Mendenhall, Marcus H.; Sierawski, B.D.

    2009-01-01

    Use of low-energy protons and high-energy light ions is becoming necessary to investigate current-generation SEU thresholds. Systematic errors can dominate measurements made with low-energy protons. Range and energy straggling contribute to systematic error. Low-energy proton testing is not a step-and-repeat process. Low-energy protons and high-energy light ions can be used to measure SEU cross section of single sensitive features; important for simulation.

  20. Low-Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Wiedenbeck, M. E.; ACE/CRIS Collaboration

    2002-12-01

    Cosmic rays with energies below about 10 GeV/nucleon have been measured with high precision as a result of experiments on the HEAO, Ulysses, and ACE spacecrafts. The observations provide energy spectra, elemental abundances, and isotopic composition for elements up through Z=30. They include both stable and radioactive nuclides that are synthesized in stars or are produced by nuclear fragmentation during diffusion at high energies through interstellar medium. From these data one obtains a rather detailed picture of the origin of low-energy cosmic rays. For refractory species, the cosmic-ray source composition closely resembles that of the Sun, suggesting that cosmic rays are accelerated from a well-mixed sample of interstellar matter. A chemical fractionation process has depleted the abundances of volatile elements relative to refractories. Using various radioactive clock isotopes it has been shown that particle acceleration occurs at least 105 years after supernova nucleosynthesis and that the accelerated particles diffuse in the Galaxy for approximately 15 Myr after acceleration. Energy spectra and secondary-to-primary ratios are reasonably well accounted for by models in which particles gain the bulk of their energy in a single encounter with a strong shock. Among the large number of species that have been measured, 22Ne stands out as the only nuclide with an abundance that is clearly much different than solar. To test models proposed to account for this anomaly, the data are being analyzed for predicted smaller effects on abundances of other nuclides. In addition to providing a detailed understanding of the origin and acceleration of low-energy cosmic rays, these data are providing constraints on the chemical evolution of interstellar matter. This work was supported by NASA at Caltech (under grant NAG5-6912), JPL, NASA/GSFC, and Washington U.

  1. IBS and possible luminosity improvement for RHIC operation below transition energy

    SciTech Connect

    Fedotov,A.V.

    2009-05-04

    There is a strong interest in low-energy RHIC collisions in the energy range below present RHIC transition energy. These collisions win help to answer one of the key questions in the field of QCD about the existence and location of a critical point on the QCD phase diagram. For such low-energy RHIC operation, particle losses from the RF bucket are of particular concern since the longitudinal beam size is comparable to the existing RF bucket at low energies. In this paper, we explore an Intrabeam Scattering (IBS) feature below transition energy that drives the transverse and longitudinal beam temperatures towards equilibrium to see whether we can minimize longitudinal diffusion due to IBS and predict some luminosity improvement for the low-energy RHIC project.

  2. Sharp transitions in low-number quantum dots Bayesian magnetometry

    NASA Astrophysics Data System (ADS)

    Mazurek, Paweł; Horodecki, Michał; Czekaj, Łukasz; Horodecki, Paweł

    2016-09-01

    We consider Bayesian estimate of static magnetic field, characterized by a prior Gaussian probability distribution, in systems of a few electron quantum dot spins interacting with infinite temperature spin environment via hyperfine interaction. Sudden transitions among optimal states and measurements are observed. Usefulness of measuring occupation levels is shown for all times of the evolution, together with the role of entanglement in the optimal scenario. For low values of magnetic field, memory effects stemming from the interaction with environment provide limited metrological advantage.

  3. Low-Energy Sputtering Research

    NASA Technical Reports Server (NTRS)

    Ray, P. K.; Shutthanandan, V.

    1999-01-01

    An experimental study is described to measure low-energy (less than 600 eV) sputtering yields of molybdenum with xenon ions using Rutherford backscattering spectroscopy (RBS) and secondary neutral mass spectroscopy (SNMS). An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 (micro)A/sq cm. For RBS measurements, the sputtered material was collected on a thin aluminum strip which was mounted on a semi-circular collector plate. The target was bombarded with 200 and 500 eV xenon ions at normal incidence. The differential sputtering yields were measured using the RBS method with 1 MeV helium ions. The differential yields were fitted with a cosine fitting function and integrated with respect to the solid angle to provide the total sputtering yields. The sputtering yields obtained using the RBS method are in reasonable agreement with those measured by other researchers using different techniques. For the SNMS measurements, 150 to 600 eV xenon ions were used at 50deg angle of incidence. The SNMS spectra were converted to sputtering yields for perpendicular incidence by normalizing SNMS spectral data at 500 eV with the yield measured by Rutherford backscattering spectrometry. Sputtering yields as well as the shape of the yield-energy curve obtained in this manner are in reasonable agreement with those measured by other researchers using different techniques. Sputtering yields calculated by using two semi-spherical formulations agree reasonably well with measured data. The isotopic composition of secondary ions were measured by bombarding copper with xenon ions at energies ranging from 100 eV to 1.5 keV. The secondary ion flux was found to be enriched in heavy isotopes at low incident ion energies. The heavy isotope enrichment was observed to decrease with increasing impact energy. Beyond 700 eV, light isotopes were sputtered preferentially with the enrichment remaining nearly constant.

  4. RHIC low-energy challenges and plans

    SciTech Connect

    Satogata,T.; Ahrens, L.; Bai, M.; Brennan, J.M.; Bruno, D.; Butler, J.; Drees, A.; Fedotov, A.; Fischer, W.; Harvey, M.; Hayes, T.; Jappe, W.; Lee, R.C.; MacKay, W.W.; Malitsky, N.; Marr, G.; Michnoff, R.; Oerter, B.; Pozdeyev, E.; Roser, T.; Schoefer, V.; Severino, F.; Smith, K.; Tepikian, S.; Tsoupas, N.

    2009-06-08

    Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by the search for a possible QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy {radical}s = 19.6 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with these challenges during beam tests with gold beams in March 2008. This includes first operations at {radical}s = 9.18 GeV/n, first beam experience at {radical}s = 5 GeV/n, and luminosity projections for near-term operations.

  5. Near-optimal energy transitions for energy-state trajectories of hypersonic aircraft

    NASA Astrophysics Data System (ADS)

    Ardema, M. D.; Bowles, J. V.; Terjesen, E. J.; Whittaker, T.

    1992-08-01

    A problem of the instantaneous energy transition that occurs in energy-state approximation is considered. The transitions are modeled as a sequence of two load-factor bounded paths (either climb-dive or dive-climb). The boundary-layer equations associated with the energy-state dynamic model are analyzed to determine the precise location of the transition.

  6. Beam lifetime and limitations during low-energy RHIC operation

    SciTech Connect

    Fedotov, A.V.; Bai, M.; Blaskiewicz, M.; Fischer, W.; Kayran, D.; Montag, C.; Satogata, T.; Tepikian, S.; Wang, G.

    2011-03-28

    The low-energy physics program at the Relativistic Heavy Ion Collider (RHIC), motivated by a search for the QCD phase transition critical point, requires operation at low energies. At these energies, large nonlinear magnetic field errors and large beam sizes produce low beam lifetimes. A variety of beam dynamics effects such as Intrabeam Scattering (IBS), space charge and beam-beam forces also contribute. All these effects are important to understand beam lifetime limitations in RHIC at low energies. During the low-energy RHIC physics run in May-June 2010 at beam {gamma} = 6.1 and {gamma} = 4.1, gold beam lifetimes were measured for various values of space-charge tune shifts, transverse acceptance limitation by collimators, synchrotron tunes and RF voltage. This paper summarizes our observations and initial findings.

  7. Acceleressence: Dark energy from a phase transition at the seesawscale

    SciTech Connect

    Chacko, Z.; Hall, Lawrence J.; Nomura, Yasunori

    2004-10-05

    Simple models are constructed for ''acceleressence'' dark energy: the latent heat of a phase transition occurring in a hidden sector governed by the seesaw mass scale v{sup 2}/M{sub Pl}, where v is the electroweak scale and M{sub Pl} the gravitational mass scale. In our models, the seesaw scale is stabilized by supersymmetry, implying that the LHC must discover superpartners with a spectrum that reflects a low scale of fundamental supersymmetry breaking. Newtonian gravity may be modified by effects arising from the exchange of fields in the acceleressence sector whose Compton wavelengths are typically of order the millimeter scale. There are two classes of models. In the first class the universe is presently in a metastable vacuum and will continue to inflate until tunneling processes eventually induce a first order transition. In the simplest such model, the range of the new force is bounded to be larger than 25 {micro}m in the absence of fine-tuning of parameters, and for couplings of order unity it is expected to be {approx} 100 {micro}m. In the second class of models thermal effects maintain the present vacuum energy of the universe, but on further cooling, the universe will ''soon'' smoothly relax to a matter dominated era. In this case, the range of the new force is also expected to be of order the millimeter scale or larger, although its strength is uncertain. A firm prediction of this class of models is the existence of additional energy density in radiation at the eV era, which can potentially be probed in precision measurements of the cosmic microwave background. An interesting possibility is that the transition towards a matter dominated era has occurred in the very recent past, with the consequence that the universe is currently decelerating.

  8. Solar-assisted low energy dwellings

    SciTech Connect

    Esbensen, T V

    1980-02-01

    The Zero Energy House Group was formed as a subproject of the CCMS Solar Energy Pilot Study in 1974 by seven participating countries experimenting with solar-assisted low-energy dwellings for temperate and northern European climatic conditions. A Zero Energy House is one in which solar energy is used to meet the reduced energy needs of buildings incorporating various thermal energy conservation features. This final report of the Zero Energy House Group includes brief descriptions of 13 major low-energy dwellings in the participating CCMS countries. An overall assessment of the state-of-the-art in solar-assisted low-energy dwellings is also included.

  9. Intense low energy positron beams

    SciTech Connect

    Lynn, K.G.; Jacobsen, F.M.

    1993-12-31

    Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

  10. Low energy consumption spintronics using multiferroic heterostructures.

    PubMed

    Trassin, Morgan

    2016-01-27

    We review the recent progress in the field of multiferroic magnetoelectric heterostructures. The lack of single phase multiferroic candidates exhibiting simultaneously strong and coupled magnetic and ferroelectric orders led to an increased effort into the development of artificial multiferroic heterostructures in which these orders are combined by assembling different materials. The magnetoelectric coupling emerging from the created interface between the ferroelectric and ferromagnetic layers can result in electrically tunable magnetic transition temperature, magnetic anisotropy or magnetization reversal. The full potential of low energy consumption magnetic based devices for spintronics lies in our understanding of the magnetoelectric coupling at the scale of the ferroic domains. Although the thin film synthesis progresses resulted into the complete control of ferroic domain ordering using epitaxial strain, the local observation of magnetoelectric coupling remains challenging. The ability to imprint ferroelectric domains into ferromagnets and to manipulate those solely using electric fields suggests new technological advances for spintronics such as magnetoelectric memories or memristors.

  11. Towards Low Energy Atrial Defibrillation.

    PubMed

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiac impedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50% magnitude) shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50-300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p < 0.01) while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA) within the same patient group (|∆(IAMSAS1-IAMSAS3)[1 Hz - 20 kHz] = 20.82 Ω-Hz (SD(σ) = 10.77 Ω-Hz), p < 0.01); both trends being absent in all patients that failed to cardiovert. Efficient

  12. Towards Low Energy Atrial Defibrillation

    PubMed Central

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiacimpedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50% magnitude) shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50–300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p < 0.01) while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA) within the same patient group (|∆(IAMSAS1-IAMSAS3)[1 Hz − 20 kHz] = 20.82 Ω-Hz (SD(σ) = 10.77 Ω-Hz), p < 0.01); both trends being absent in all patients that failed to cardiovert. Efficient

  13. Sharp transitions in low-number quantum dots Bayesian magnetometry

    PubMed Central

    Mazurek, Paweł; Horodecki, Michał; Czekaj, Łukasz; Horodecki, Paweł

    2016-01-01

    We consider Bayesian estimate of static magnetic field, characterized by a prior Gaussian probability distribution, in systems of a few electron quantum dot spins interacting with infinite temperature spin environment via hyperfine interaction. Sudden transitions among optimal states and measurements are observed. Usefulness of measuring occupation levels is shown for all times of the evolution, together with the role of entanglement in the optimal scenario. For low values of magnetic field, memory effects stemming from the interaction with environment provide limited metrological advantage. PMID:27686417

  14. Bridging analytical approaches for low-carbon transitions

    NASA Astrophysics Data System (ADS)

    Geels, Frank W.; Berkhout, Frans; van Vuuren, Detlef P.

    2016-06-01

    Low-carbon transitions are long-term multi-faceted processes. Although integrated assessment models have many strengths for analysing such transitions, their mathematical representation requires a simplification of the causes, dynamics and scope of such societal transformations. We suggest that integrated assessment model-based analysis should be complemented with insights from socio-technical transition analysis and practice-based action research. We discuss the underlying assumptions, strengths and weaknesses of these three analytical approaches. We argue that full integration of these approaches is not feasible, because of foundational differences in philosophies of science and ontological assumptions. Instead, we suggest that bridging, based on sequential and interactive articulation of different approaches, may generate a more comprehensive and useful chain of assessments to support policy formation and action. We also show how these approaches address knowledge needs of different policymakers (international, national and local), relate to different dimensions of policy processes and speak to different policy-relevant criteria such as cost-effectiveness, socio-political feasibility, social acceptance and legitimacy, and flexibility. A more differentiated set of analytical approaches thus enables a more differentiated approach to climate policy making.

  15. Substituent effect on electronic transition energy of dichlorobenzyl radicals

    NASA Astrophysics Data System (ADS)

    Yoon, Young Wook; Chae, Sang Youl; Lee, Sang Kuk

    2016-01-01

    Ring-substituted benzyl radicals exhibit electronic energies of the D1 → D0 transition being shifted to red region with respect to the benzyl radical. The red-shifts of disubstituted benzyl radicals are highly dependent on the substitution positions irrespective of substituents. By analyzing the red-shifts of dichlorobenzyl radicals observed, we found that the substituent effect on electronic transition energy is attributed to the molecular plane shape of delocalized π electrons. We will discuss the influences of locations of Cl substituents on the D1 → D0 transition energies of dichlorobenzyl radicals using Hückel's molecular orbital theory.

  16. Funding pathways to a low-carbon transition

    NASA Astrophysics Data System (ADS)

    Foulds, Chris; Christensen, Toke Haunstrup

    2016-07-01

    The framing of funding programmes can sustain existing ways of conceptualizing particular problems, as well as create new ones. Yet, without more prominent roles for social sciences and humanities, the techno-economic conceptualization of energy consumers could hinder long-term low-carbon aspirations.

  17. Trends in Ionization Energy of Transition-Metal Elements

    ERIC Educational Resources Information Center

    Matsumoto, Paul S.

    2005-01-01

    A rationale for the difference in the periodic trends in the ionization energy of the transition-metal elements versus the main-group elements is presented. The difference is that in the transition-metal elements, the electrons enter an inner-shell electron orbital, while in the main-group elements, the electrons enter an outer-shell electron…

  18. [Relationships between settlement morphology transition and residents commuting energy consumption].

    PubMed

    Zhou, Jian; Xiao, Rong-Bo; Sun, Xiang

    2013-07-01

    Settlement morphology transition is triggered by rapid urbanization and urban expansion, but its relationships with residents commuting energy consumption remains ambiguous. It is of significance to understand the controlling mechanisms of sustainable public management policies on the energy consumption and greenhouse gases emission during the process of urban settlement morphology transition. Taking the Xiamen City of East China as a case, and by using the integrated land use and transportation modeling system TRANUS, a scenario analysis was made to study the effects of urban settlement morphology transition on the urban spatial distribution of population, jobs, and land use, and on the residents commuting energy consumption and greenhouse gasses emission under different scenarios. The results showed that under the Business As Usual (BAU) scenario, the energy consumption of the residents at the morning peak travel time was 54.35 tce, and the CO2 emission was 119.12 t. As compared with those under BAU scenario, both the energy consumption and the CO2 emission under the Transition of Settlement Morphology (TSM) scenario increased by 12%, and, with the implementation of the appropriate policies such as land use, transportation, and economy, the energy consumption and CO2 emission under the Transition of Settlement Morphology with Policies (TSMP) scenario reduced by 7%, indicating that urban public management policies could effectively control the growth of residents commuting energy consumption and greenhouse gases emission during the period of urban settlement morphology transition.

  19. A closely packed system of low-mass, low-density planets transiting Kepler-11.

    PubMed

    Lissauer, Jack J; Fabrycky, Daniel C; Ford, Eric B; Borucki, William J; Fressin, Francois; Marcy, Geoffrey W; Orosz, Jerome A; Rowe, Jason F; Torres, Guillermo; Welsh, William F; Batalha, Natalie M; Bryson, Stephen T; Buchhave, Lars A; Caldwell, Douglas A; Carter, Joshua A; Charbonneau, David; Christiansen, Jessie L; Cochran, William D; Desert, Jean-Michel; Dunham, Edward W; Fanelli, Michael N; Fortney, Jonathan J; Gautier, Thomas N; Geary, John C; Gilliland, Ronald L; Haas, Michael R; Hall, Jennifer R; Holman, Matthew J; Koch, David G; Latham, David W; Lopez, Eric; McCauliff, Sean; Miller, Neil; Morehead, Robert C; Quintana, Elisa V; Ragozzine, Darin; Sasselov, Dimitar; Short, Donald R; Steffen, Jason H

    2011-02-01

    When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital shapes, and the fraction of transiting planets observed as multiples has implications for the planarity of planetary systems. But few stars have more than one known transiting planet, and none has more than three. Here we report Kepler spacecraft observations of a single Sun-like star, which we call Kepler-11, that reveal six transiting planets, five with orbital periods between 10 and 47 days and a sixth planet with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases. The degree of coplanarity and proximity of the planetary orbits imply energy dissipation near the end of planet formation.

  20. A closely packed system of low-mass, low-density planets transiting Kepler-11.

    PubMed

    Lissauer, Jack J; Fabrycky, Daniel C; Ford, Eric B; Borucki, William J; Fressin, Francois; Marcy, Geoffrey W; Orosz, Jerome A; Rowe, Jason F; Torres, Guillermo; Welsh, William F; Batalha, Natalie M; Bryson, Stephen T; Buchhave, Lars A; Caldwell, Douglas A; Carter, Joshua A; Charbonneau, David; Christiansen, Jessie L; Cochran, William D; Desert, Jean-Michel; Dunham, Edward W; Fanelli, Michael N; Fortney, Jonathan J; Gautier, Thomas N; Geary, John C; Gilliland, Ronald L; Haas, Michael R; Hall, Jennifer R; Holman, Matthew J; Koch, David G; Latham, David W; Lopez, Eric; McCauliff, Sean; Miller, Neil; Morehead, Robert C; Quintana, Elisa V; Ragozzine, Darin; Sasselov, Dimitar; Short, Donald R; Steffen, Jason H

    2011-02-01

    When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital shapes, and the fraction of transiting planets observed as multiples has implications for the planarity of planetary systems. But few stars have more than one known transiting planet, and none has more than three. Here we report Kepler spacecraft observations of a single Sun-like star, which we call Kepler-11, that reveal six transiting planets, five with orbital periods between 10 and 47 days and a sixth planet with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases. The degree of coplanarity and proximity of the planetary orbits imply energy dissipation near the end of planet formation. PMID:21293371

  1. Energy level transitions of gas in a 2D nanopore

    SciTech Connect

    Grinyaev, Yurii V.; Chertova, Nadezhda V.; Psakhie, Sergei G.

    2015-10-27

    An analytical study of gas behavior in a 2D nanopore was performed. It is shown that the temperature dependence of gas energy can be stepwise due to transitions from one size-quantized subband to another. Taking into account quantum size effects results in energy level transitions governed by the nanopore size, temperature and gas density. This effect leads to an abrupt change of gas heat capacity in the nanopore at the above varying system parameters.

  2. Rail transit energy management program: Energy database. Volume 2. Final report

    SciTech Connect

    Uher, R.A.

    1995-03-01

    The Rail Transportation Energy Management Program (EMP) is a private/public partnership whose objective is to reduce rail transit energy cost and improve energy efficiency. The Energy Database (EDB) was set up under the program. The purpose of the EDB is to provide information to the members of the program. This information includes rail transit energy and energy cost data and the results of implementation of energy cost reduction strategies. The EDB also includes a means for timely exchange of information among transit authorities as well as associated with energy management. The database is presently set up on a personal computer and is accessed by the users via an 800 telephone line.

  3. Battery energy storage for rail transit systems. Technical report

    SciTech Connect

    Uher, R.A.

    1996-04-01

    A battery simulation model was developed to work in conjunction with the Rail Transit Energy Management Model (EMM) to estimate the performance of battery energy storage on rail transit systems. This model uses a battery which is connected directly to the DC bus at a substation. No power conditioning equipment is involved, thus reducing the cost of a battery station substantially. Although these types of battery stations could be used for peak load shaving, voltage boost, and increasing energy receptivity on a system with regenerating trains, it was found that the last of these uses proved economically feasible. Because energy receptivity is increased, the peak load will also be shaved.

  4. KEPLER-7b: A TRANSITING PLANET WITH UNUSUALLY LOW DENSITY

    SciTech Connect

    Latham, David W.; Buchhave, Lars A.; Furesz, Gabor; Geary, John C.; Borucki, William J.; Koch, David G.; Lissauer, Jack J.; Rowe, Jason F.; Brown, Timothy M.; Basri, Gibor; Batalha, Natalie M.; Caldwell, Douglas A.; Jenkins, Jon M.; Cochran, William D.; Dunham, Edward W.; Gautier, Thomas N.; Howell, Steve B.; Marcy, Geoffrey W.; Monet, David G.

    2010-04-20

    We report on the discovery and confirmation of Kepler-7b, a transiting planet with unusually low density. The mass is less than half that of Jupiter, M {sub P} = 0.43 M {sub J}, but the radius is 50% larger, R {sub P} = 1.48 R {sub J}. The resulting density, {rho}{sub P} = 0.17 g cm{sup -3}, is the second lowest reported so far for an extrasolar planet. The orbital period is fairly long, P = 4.886 days, and the host star is not much hotter than the Sun, T {sub eff} = 6000 K. However, it is more massive and considerably larger than the Sun, M {sub *} = 1.35 M {sub sun} and R {sub *} = 1.84 R {sub sun}, and must be near the end of its life on the main sequence.

  5. Minimum energy paths of wetting transitions on grooved surfaces.

    PubMed

    Pashos, George; Kokkoris, George; Boudouvis, Andreas G

    2015-03-17

    A method that computes minimum energy paths (MEPs) of wetting transitions is developed. The method couples the Cahn-Hilliard formulation of a modified phase-field method with the simplified string method. Its main computational kernel is the fast Fourier transform that is efficiently performed on graphics processing units. The effectiveness of the proposed method is demonstrated on two types of transitions of droplets on grooved surfaces. The first is the transition from the Cassie-Baxter wetting state to the Wenzel state, where it is shown that it progresses in a sequential manner with the droplet wetting each groove successively. The second transition type is a lateral displacement of the droplet against the grooves, where the droplet successively detaches/attaches from/to the rear/front protrusion of the surface (a transition in the reverse order is also possible). The energy barriers of both the transitions are extracted from the MEP; they are useful for the evaluation of the robustness of superhydrophobic surfaces (resistance to the Cassie-Baxter to Wenzel transition) and the droplet mobility on those surfaces (high mobility/small resistance to lateral displacements). The relation of the MEP with the potential transition paths coming from the solution space mapping is discussed. PMID:25715270

  6. The transition to the metallic state in low density hydrogen.

    PubMed

    McMinis, Jeremy; Morales, Miguel A; Ceperley, David M; Kim, Jeongnim

    2015-11-21

    Solid atomic hydrogen is one of the simplest systems to undergo a metal-insulator transition. Near the transition, the electronic degrees of freedom become strongly correlated and their description provides a difficult challenge for theoretical methods. As a result, the order and density of the phase transition are still subject to debate. In this work, we use diffusion quantum Monte Carlo to benchmark the transition between paramagnetic and anti-ferromagnetic body centered cubic atomic hydrogen in its ground state. We locate the density of the transition by computing the equation of state for these two phases and identify the phase transition order by computing the band gap near the phase transition. These benchmark results show that the phase transition is continuous and occurs at a Wigner-Seitz radius of rs = 2.27(3) a0. We compare our results to previously reported density functional theory, Hedin's GW approximation, and dynamical mean field theory results. PMID:26590549

  7. Understanding the human dimensions of a sustainable energy transition

    PubMed Central

    Steg, Linda; Perlaviciute, Goda; van der Werff, Ellen

    2015-01-01

    Global climate change threatens the health, economic prospects, and basic food and water sources of people. A wide range of changes in household energy behavior is needed to realize a sustainable energy transition. We propose a general framework to understand and encourage sustainable energy behaviors, comprising four key issues. First, we need to identify which behaviors need to be changed. A sustainable energy transition involves changes in a wide range of energy behaviors, including the adoption of sustainable energy sources and energy-efficient technology, investments in energy efficiency measures in buildings, and changes in direct and indirect energy use behavior. Second, we need to understand which factors underlie these different types of sustainable energy behaviors. We discuss three main factors that influence sustainable energy behaviors: knowledge, motivations, and contextual factors. Third, we need to test the effects of interventions aimed to promote sustainable energy behaviors. Interventions can be aimed at changing the actual costs and benefits of behavior, or at changing people’s perceptions and evaluations of different costs and benefits of behavioral options. Fourth, it is important to understand which factors affect the acceptability of energy policies and energy systems changes. We discuss important findings from psychological studies on these four topics, and propose a research agenda to further explore these topics. We emphasize the need of an integrated approach in studying the human dimensions of a sustainable energy transition that increases our understanding of which general factors affect a wide range of energy behaviors as well as the acceptability of different energy policies and energy system changes. PMID:26136705

  8. Understanding the human dimensions of a sustainable energy transition.

    PubMed

    Steg, Linda; Perlaviciute, Goda; van der Werff, Ellen

    2015-01-01

    Global climate change threatens the health, economic prospects, and basic food and water sources of people. A wide range of changes in household energy behavior is needed to realize a sustainable energy transition. We propose a general framework to understand and encourage sustainable energy behaviors, comprising four key issues. First, we need to identify which behaviors need to be changed. A sustainable energy transition involves changes in a wide range of energy behaviors, including the adoption of sustainable energy sources and energy-efficient technology, investments in energy efficiency measures in buildings, and changes in direct and indirect energy use behavior. Second, we need to understand which factors underlie these different types of sustainable energy behaviors. We discuss three main factors that influence sustainable energy behaviors: knowledge, motivations, and contextual factors. Third, we need to test the effects of interventions aimed to promote sustainable energy behaviors. Interventions can be aimed at changing the actual costs and benefits of behavior, or at changing people's perceptions and evaluations of different costs and benefits of behavioral options. Fourth, it is important to understand which factors affect the acceptability of energy policies and energy systems changes. We discuss important findings from psychological studies on these four topics, and propose a research agenda to further explore these topics. We emphasize the need of an integrated approach in studying the human dimensions of a sustainable energy transition that increases our understanding of which general factors affect a wide range of energy behaviors as well as the acceptability of different energy policies and energy system changes.

  9. Understanding the human dimensions of a sustainable energy transition.

    PubMed

    Steg, Linda; Perlaviciute, Goda; van der Werff, Ellen

    2015-01-01

    Global climate change threatens the health, economic prospects, and basic food and water sources of people. A wide range of changes in household energy behavior is needed to realize a sustainable energy transition. We propose a general framework to understand and encourage sustainable energy behaviors, comprising four key issues. First, we need to identify which behaviors need to be changed. A sustainable energy transition involves changes in a wide range of energy behaviors, including the adoption of sustainable energy sources and energy-efficient technology, investments in energy efficiency measures in buildings, and changes in direct and indirect energy use behavior. Second, we need to understand which factors underlie these different types of sustainable energy behaviors. We discuss three main factors that influence sustainable energy behaviors: knowledge, motivations, and contextual factors. Third, we need to test the effects of interventions aimed to promote sustainable energy behaviors. Interventions can be aimed at changing the actual costs and benefits of behavior, or at changing people's perceptions and evaluations of different costs and benefits of behavioral options. Fourth, it is important to understand which factors affect the acceptability of energy policies and energy systems changes. We discuss important findings from psychological studies on these four topics, and propose a research agenda to further explore these topics. We emphasize the need of an integrated approach in studying the human dimensions of a sustainable energy transition that increases our understanding of which general factors affect a wide range of energy behaviors as well as the acceptability of different energy policies and energy system changes. PMID:26136705

  10. The carbon-consuming home: residential markets and energy transitions.

    PubMed

    Jones, Christopher

    2011-01-01

    Home heating and lighting markets have played crucial and underappreciated roles in driving energy transitions. When historians have studied the adoption of fossil fuels, they have often privileged industrial actors, markets, and technologies. My analysis of the factors that stimulated the adoption of anthracite coal and petroleum during the nineteenth century reveals that homes shaped how, when, and why Americans began to use fossil fuel energy. Moreover, a brief survey of other fossil fuel transitions shows that heating and lighting markets have been critical drivers in other times and places. Reassessing the historical patterns of energy transitions offers a revised understanding of the past for historians and suggests a new set of options for policymakers seeking to encourage the use of renewable energy in the future.

  11. The carbon-consuming home: residential markets and energy transitions.

    PubMed

    Jones, Christopher

    2011-01-01

    Home heating and lighting markets have played crucial and underappreciated roles in driving energy transitions. When historians have studied the adoption of fossil fuels, they have often privileged industrial actors, markets, and technologies. My analysis of the factors that stimulated the adoption of anthracite coal and petroleum during the nineteenth century reveals that homes shaped how, when, and why Americans began to use fossil fuel energy. Moreover, a brief survey of other fossil fuel transitions shows that heating and lighting markets have been critical drivers in other times and places. Reassessing the historical patterns of energy transitions offers a revised understanding of the past for historians and suggests a new set of options for policymakers seeking to encourage the use of renewable energy in the future. PMID:22213886

  12. Scattering of low-energy neutrinos on atomic shells

    SciTech Connect

    Babič, Andrej; Šimkovic, Fedor

    2015-10-28

    We present a derivation of the total cross section for inelastic scattering of low-energy solar neutrinos and reactor antineutrinos on bound electrons, resulting in a transition of the electron to an excited state. The atomic-shell structure of various chemical elements is treated in terms of a nonrelativistic approximation. We estimate the interaction rates for modern neutrino detectors, in particular the Borexino and GEMMA experiments. We establish that in these experiments the effect can be safely neglected, but it could be accessible to future large-volume neutrino detectors with low energy threshold.

  13. Two Transiting Low Density Sub-Saturns from K2

    NASA Astrophysics Data System (ADS)

    Petigura, Erik A.; Howard, Andrew W.; Lopez, Eric D.; Deck, Katherine M.; Fulton, Benjamin J.; Crossfield, Ian J. M.; Ciardi, David R.; Chiang, Eugene; Lee, Eve J.; Isaacson, Howard; Beichman, Charles A.; Hansen, Brad M. S.; Schlieder, Joshua E.; Sinukoff, Evan

    2016-02-01

    We report the discovery and confirmation of K2-24 b and c, two sub-Saturn planets orbiting a bright (V = 11.3), metal-rich ([Fe/H] = 0.42 ± 0.04 dex) G3 dwarf in the K2 Campaign 2 field. The planets are 5.68 ± 0.56 {R}\\oplus and 7.82 ± 0.72 {R}\\oplus and have orbital periods of 20.8851 ± 0.0003 days and 42.3633 ± 0.0006 days, near the 2:1 mean-motion resonance. We obtained 32 radial velocities with Keck/HIRES and detected the reflex motion due to K2-24 b and c. These planets have masses of 21.0 ± 5.4 {M}\\oplus and 27.0 ± 6.9 {M}\\oplus , respectively. With low densities of 0.63 ± 0.25 g cm-3 and 0.31 ± 0.12 g cm-3, respectively, the planets require thick envelopes of H/He to explain their large sizes and low masses. Interior structure models predict that the planets have fairly massive cores of 17.6+/- 4.3 {M}\\oplus and 16.1+/- 4.2 {M}\\oplus , respectively. They may have formed exterior to their present locations, accreted their H/He envelopes at large orbital distances, and migrated in as a resonant pair. The proximity to resonance, large transit depths, and host star brightness offers rich opportunities for TTV follow-up. Finally, the low surface gravities of the K2-24 planets make them favorable targets for transmission spectroscopy by Hubble Space Telescope, Spitzer, and James Webb Space Telescope.

  14. Energy levels and multipole transition properties of C4+ ion in Debye plasmas

    NASA Astrophysics Data System (ADS)

    Xie, L. Y.; Wang, J. G.; Janev, R. K.; Qu, Y. Z.; Dong, C. Z.

    2012-05-01

    Plasma screening effects on the energy structure and radiative transition properties of helium-like C4+ ions embedded in Debye plasmas are investigated by using the multi-configuration Dirac-Hartree-Fock method incorporating the Debye-Hückel potential for both the electron-nucleus and electron-electron interactions. Seventeen fine-structure energy levels of the low-lying 1 s 2, 1 s2 l( l = s,p) and 1 s3 l'( l' = s,p,d) configurations, as well as the electric-dipole ( E1), magnetic-dipole ( M1) and magnetic-quadrupole ( M2) transition probabilities and oscillator strengths between these levels have been calculated over a wide range of screening parameters. It is found that the plasma screening leads to a decrease of excitation energies and alters the energy levels remarkably. For Δn ≠ 0 transitions, the spontaneous decay spectra are red-shifted and their oscillator strengths and transition probabilities decrease with increasing the interaction screening, while those for the Δn = 0 transitions exhibit opposite patterns. The influence of electron-nucleus and electron-electron screened interactions on the changes of energy levels and transition properties are analyzed. Comparison is made of present results with other data available in the literature for this ion.

  15. Investigation of low glass transition temperature on COTS PEM's reliability for space applications

    NASA Technical Reports Server (NTRS)

    Sandor, M.; Agarwal, S.; Peters, D.; Cooper, M. S.

    2003-01-01

    Plastic Encapsulated Microelectronics (PEM) reliability is affected by many factors. Glass transition temperature (Tg) is one such factor. In this presentation issues relating to PEM reliability and the effect of low glass transition temperature epoxy mold compounds are presented.

  16. Low Energy Building for High Energy People.

    ERIC Educational Resources Information Center

    American School and University, 1982

    1982-01-01

    The Huston Huffman Center at the University of Oklahoma's Norman campus has a jogging track as well as facilities for exercise and court games that are fully accessible to the handicapped. The building is set eight feet in the ground both to reduce its bulk and to conserve energy. (Author/MLF)

  17. Reference free, high-precision measurements of transition energies in few electron argon ions

    NASA Astrophysics Data System (ADS)

    Szabo, Csilla I.; Amaro, Pedro; Guerra, Mauro; Schlesser, Sophie; Gumberidze, Alexander; Santos, José Paulo; Indelicato, Paul

    2013-04-01

    The use of a vacuum double crystal spectrometer, coupled to an electron-cyclotron resonance ion source (ECRIS), allows to measure low-energy x-ray transitions energies in highly-charged ions with accuracies of the order of a few parts per million. We have used this installation to measure the 1s2p 1 P1 → 1s2 1 S0 diagram line and the 1s2s 3 S1 → 1s2 1 S0 forbidden M1 transition energies in helium-like argon, the 1s2s2p 2 Pj → 1s2 2s 2 S1/2 transitions in lithium-like argon and the 1s2s2 2p 1 P1 → 1s2 2s2 1 S0 transition in beryllium-like argon. These transition measurements have accuracies between 2 and 4 ppm depending on the line intensity. Thanks to the excellent agreement between the simulations and the measurements, we were also able to measure the transition width of all the allowed transitions. The results are compared to recent QED and relativistic many-body calculations.

  18. STATE TRANSITIONS IN LOW-MASS X-RAY BINARIES

    SciTech Connect

    Bradley, Charles K.; Frank, Juhan

    2009-10-10

    We investigate the model of disk/coronal accretion into a black hole. We show that the inner regions of an accretion disk in X-ray binaries can transform from a cool standard disk to an advection-dominated flow through the known properties of Coulomb interaction in a two-temperature plasma, viscous heating, radiative processes, and thermal conduction. A hot, diffuse corona covering the disk is powered by accretion, but it exchanges mass with the underlying cold disk. If the accretion rate in the system is low enough, we show that the corona evaporates the disk away, leaving an advective flow to continue toward the hole. In the soft/hard transition commonly seen in X-ray binaries, we show that this advective flow can recondense back onto the underlying disk if the change in the system's accretion rate is slow enough due to thermal conduction. Unabsorbed spectra are produced to test against observations as well as prediction of the location of truncation radii of the accretion disk.

  19. Structural phase transitions in low-dimensional ion crystals

    SciTech Connect

    Fishman, Shmuel; Chiara, Gabriele de; Calarco, Tommaso; Morigi, Giovanna

    2008-02-01

    A chain of singly charged particles, confined by a harmonic potential, exhibits a sudden transition to a zigzag configuration when the radial potential reaches a critical value, depending on the particle number. This structural change is a phase transition of second order, whose order parameter is the crystal displacement from the chain axis. We study analytically the transition using Landau theory and find full agreement with numerical predictions by Schiffer [Phys. Rev. Lett. 70, 818 (1993)] and Piacente et al. [Phys. Rev. B 69, 045324 (2004)]. Our theory allows us to determine analytically the system's behavior at the transition point.

  20. Securing the Extremely Low-Densities of Low-Mass Planets Characterized by Transit Timing Variations

    NASA Astrophysics Data System (ADS)

    Ford, Eric B.

    2015-12-01

    Transit timing variations (TTVs) provide an excellent tool to characterize the masses and orbits of dozens of small planets, including many at orbital periods beyond the reach of both Doppler surveys and photoevaporation-induced atmospheric loss. Dynamical modeling of these systems has identified low-mass planets with surprisingly large radii and low densities (e.g., Kepler-79d, Jontof-Hutter et al. 2014; Kepler-51, Masuda 2014; Kepler-87c, Ofir et al. 2014). Additional low-density, low-mass planets will likely become public before ESS III (Jontof-Hutter et al. in prep). Collectively, these results suggest that very low density planets with masses of 2-6 MEarth are not uncommon in compact multiple planet systems. Some astronomers have questioned whether there could be an alternative interpretation of the TTV observations. Indeed, extraordinary claims require extraordinary evidence. While the physics of TTVs is rock solid, the statistical analysis of Kepler observations can be challenging, due to the complex interactions between model parameters and high-dimensional parameter spaces that must be explored. We summarize recent advances in computational statistics that enable robust characterization of planetary systems using TTVs. We present updated analyses of a few particularly interesting systems and discuss the implications for the robustness of extremely low densities for low-mass planets. Such planets pose an interesting challenge for planet formation theory and are motivating detailed theoretical studies (e.g., Lee & Chiang 2015 and associated ESS III abstracts).

  1. Low-carbon yak cheese: transition to biogas in a Himalayan socio-technical niche

    PubMed Central

    Campbell, Ben; Sallis, Paul

    2013-01-01

    This study looks at how potential for resilient low-carbon solutions can be understood and enhanced in the diverse environmental, economic and socio-political contexts in which actual scenarios of energy needs and diverse development pathways take shape. It discusses socio-technical transition approaches to assist implementation of a biogas digester system. This will replace fuelwood use in the high forests of Central Nepal, where yak cheese production provides livelihood income but is under threat from the Langtang National Park, which is concerned to protect biodiversity. Alternatives for digester design are discussed, and the consultative issues for deliberative processes among stakeholders’ varied agendas raised. PMID:24427516

  2. Low-carbon yak cheese: transition to biogas in a Himalayan socio-technical niche.

    PubMed

    Campbell, Ben; Sallis, Paul

    2013-02-01

    This study looks at how potential for resilient low-carbon solutions can be understood and enhanced in the diverse environmental, economic and socio-political contexts in which actual scenarios of energy needs and diverse development pathways take shape. It discusses socio-technical transition approaches to assist implementation of a biogas digester system. This will replace fuelwood use in the high forests of Central Nepal, where yak cheese production provides livelihood income but is under threat from the Langtang National Park, which is concerned to protect biodiversity. Alternatives for digester design are discussed, and the consultative issues for deliberative processes among stakeholders' varied agendas raised. PMID:24427516

  3. Low energy ghosts and the Jeans' instability

    NASA Astrophysics Data System (ADS)

    Gümrükçüoǧlu, A. Emir; Mukohyama, Shinji; Sotiriou, Thomas P.

    2016-09-01

    We show that a massless canonical scalar field minimally coupled to general relativity can become a tachyonic ghost at low energies around a background in which the scalar's gradient is spacelike. By performing a canonical transformation we demonstrate that this low energy ghost can be recast, at the level of the action, in a form of a fluid that undergoes a Jeans-like instability affecting only modes with large wavelength. This illustrates that low energy tachyonic ghosts do not lead to a catastrophic quantum vacuum instability, unlike the usual high-energy ghost degrees of freedom.

  4. Transition to turbulence under low-pressure turbine conditions.

    PubMed

    Simon, T W; Kaszeta, R W

    2001-05-01

    In this paper, the topic of laminar to turbulent flow transition, as applied to the design of gas turbines, is discussed. Transition comes about when a flow becomes sufficiently unstable that the orderly vorticity structure of the laminar layer becomes randomly oriented. Vorticity with a streamwise component leads to rapid growth of eddies of a wide range of sizes and eventually to turbulent flow. Under "natural" transition, infinitesimal disturbances of selected frequencies grow. "Bypass transition" is a term coined to describe a similar process, but one driven by strong external disturbances. Transition proceeds so rapidly that the processes associated with "natural" transition seem to be "bypassed." Because the flow environment in the turbine is disturbed by wakes from upstream airfoils, eddies from combustor flows, jets from film cooling, separation zones on upstream airfoils and steps in the duct walls, transition is of the bypass mode. In this paper, we discuss work that has been done to characterize and model bypass transition, as applied to the turbine environment.

  5. Transition to turbulence under low-pressure turbine conditions.

    PubMed

    Simon, T W; Kaszeta, R W

    2001-05-01

    In this paper, the topic of laminar to turbulent flow transition, as applied to the design of gas turbines, is discussed. Transition comes about when a flow becomes sufficiently unstable that the orderly vorticity structure of the laminar layer becomes randomly oriented. Vorticity with a streamwise component leads to rapid growth of eddies of a wide range of sizes and eventually to turbulent flow. Under "natural" transition, infinitesimal disturbances of selected frequencies grow. "Bypass transition" is a term coined to describe a similar process, but one driven by strong external disturbances. Transition proceeds so rapidly that the processes associated with "natural" transition seem to be "bypassed." Because the flow environment in the turbine is disturbed by wakes from upstream airfoils, eddies from combustor flows, jets from film cooling, separation zones on upstream airfoils and steps in the duct walls, transition is of the bypass mode. In this paper, we discuss work that has been done to characterize and model bypass transition, as applied to the turbine environment. PMID:11460650

  6. The transition to the metallic state in low density hydrogen

    SciTech Connect

    McMinis, Jeremy; Morales, Miguel A.; Ceperley, David M.; Kim, Jeongnim

    2015-11-21

    Solid atomic hydrogen is one of the simplest systems to undergo a metal-insulator transition. Near the transition, the electronic degrees of freedom become strongly correlated and their description provides a difficult challenge for theoretical methods. As a result, the order and density of the phase transition are still subject to debate. In this work, we use diffusion quantum Monte Carlo to benchmark the transition between paramagnetic and anti-ferromagnetic body centered cubic atomic hydrogen in its ground state. We locate the density of the transition by computing the equation of state for these two phases and identify the phase transition order by computing the band gap near the phase transition. These benchmark results show that the phase transition is continuous and occurs at a Wigner-Seitz radius of r{sub s} = 2.27(3) a{sub 0}. We compare our results to previously reported density functional theory, Hedin’s GW approximation, and dynamical mean field theory results.

  7. The transition to the metallic state in low density hydrogen

    SciTech Connect

    McMinis, Jeremy; Morales, Miguel A.; Ceperley, David M.; Kim, Jeongnim

    2015-11-18

    Solid atomic hydrogen is one of the simplest systems to undergo a metal-insulator transition. Near the transition, the electronic degrees of freedom become strongly correlated and their description provides a difficult challenge for theoretical methods. As a result, the order and density of the phase transition are still subject to debate. In this work we use diffusion quantum Monte Carlo to benchmark the transition between the paramagnetic and anti-ferromagnetic phases of ground state body centered cubic atomic hydrogen. We locate the density of the transition by computing the equation of state for these two phases and identify the phase transition order by computing the band gap near the phase transition. These benchmark results show that the phase transition is continuous and occurs at a Wigner-Seitz radius of rs = 2.27(3)a0. As a result, we compare our results to previously reported density functional theory, Hedin s GW approximation, and dynamical mean field theory results.

  8. Observation and modeling of deflagration-to-detonation (DDT) transition in low-density HMX

    NASA Astrophysics Data System (ADS)

    Tringe, Joseph; Vandersall, Kevin; Reaugh, Jack; Levie, Harold; Henson, Bryan; Smilowitz, Laura; Parker, Gary

    2015-06-01

    We employ simultaneous flash x-ray radiography and streak imaging, together with a multi-phase finite element model, to understand deflagration-to-detonation transition (DDT) phenomena in low-density (~ 1.2 gm/cm3) powder of the explosive cyclotetramethylene-tetranitramine (HMX). HMX powder was lightly hand-tamped in a 12.7 mm diameter column, relatively lightly-confined in an optically-transparent polycarbonate cylinder with wall thickness 25.4 mm. We observe apparent compaction of the powder in advance of the detonation transition, both by x-ray contrast and by the motion of small steel spheres pre-emplaced throughout the length of explosive. High-speed imaging along the explosive cylinder length provides a temporally continuous record of the transition that is correlated with the high-resolution x-ray image record. Preliminary simulation of these experiments with the HERMES model implemented in the ALE3D code enables improved understanding of the explosive particle burning, compaction and detonation phenomena which are implied by the observed reaction rate and transition location within the cylinder. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. The Science of Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Storms, Edmund

    2007-03-01

    The large literature describing the anomalous behavior attributed to cold fusion or low energy nuclear reactions has been critically described in a recently published book. Over 950 publications are evaluated allowing the phenomenon to be understood. A new class of nuclear reactions has been discovered that are able to generate practical energy without significant radiation or radioactivity. Edmund K Storms, The Science of Low Energy Nuclear Reactions, in press (2006). Also see: http://www.lenr-canr.org/StudentsGuide.htm .

  10. A transition radiation detector prototype to measure the energy of muons in cosmic ray laboratories

    NASA Astrophysics Data System (ADS)

    Bellotti, R.; Cafagna, F.; Calicchio, M.; Castellano, M.; De Cataldo, G.; De Marzo, C.; Enriquez, O.; Favuzzi, C.; Fusco, P.; Giglietto, N.; Mongelli, M.; Nappi, E.; Perchiazzi, M.; Sacchetti, A.; Spinelli, P.

    1991-07-01

    We have developed and tested a transition radiation detector prototype suitable to measure the energy of muons in cosmic ray laboratories. The technical solutions adopted, based on extruded tubes as detectors and foam or fiber mats as radiators, allow to cover very large areas with a low number of channels and ensure stability of operation. Using an argon-carbon dioxide gas mixture it is possible to explore the muon energy range up to 1 TeV.

  11. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy Th229 Nuclear Isomeric Transition

    SciTech Connect

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T.; Rellergert, Wade G.; Mirzadeh, Saed; Cassanho, A.; Jenssen, H. P.; Tkalya, Eugene V.; Hudson, Eric R.

    2015-06-23

    We report the results of a direct search for the 229Tn (Iπ = 3/2+ ← 5/2+) nuclear isomeric transition, performed by exposing 229Tn-doped LiSrAlF6 crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1–2) s≲τ≲ (2000-5600) s. Lastly, this measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  12. Pressure and temperature induced high spin-low spin phase transition: Macroscopic and microscopic consideration

    NASA Astrophysics Data System (ADS)

    Levchenko, G.; Khristov, A.; Kuznetsova, V.; Shelest, V.

    2014-08-01

    The behavior under pressure of the high spin-low spin phase transition in the coordination compounds containing 3d ions is analyzed using thermodynamic and microscopic approaches. For thermodynamic approach the mean field model with interactions between spin-crossover molecules is considered. Microscopic model takes into account the interaction of d electrons of the transition metal ions with full symmetric distortions of the ligands. The relationship of the thermodynamic interaction parameters with microscopic ones is installed and shown how the quantum-mechanical interactions form the cooperativity of the system. Within the microscopic model the temperature and pressure dependences of the high spin fraction in 2-D compounds {Fe(3-Fpy)2[M(CN)4]} (M=Pd, Pt) are simulated and microscopic parameters are evaluated. It is concluded that different experimental behaviors of the temperature and pressure induced spin transitions are determined by different variations of the inelastic and elastic energies under pressure, and vibrational component of the free energy drives the ST equally with electronic part.

  13. The transition to the metallic state in low density hydrogen

    DOE PAGES

    McMinis, Jeremy; Morales, Miguel A.; Ceperley, David M.; Kim, Jeongnim

    2015-11-18

    Solid atomic hydrogen is one of the simplest systems to undergo a metal-insulator transition. Near the transition, the electronic degrees of freedom become strongly correlated and their description provides a difficult challenge for theoretical methods. As a result, the order and density of the phase transition are still subject to debate. In this work we use diffusion quantum Monte Carlo to benchmark the transition between the paramagnetic and anti-ferromagnetic phases of ground state body centered cubic atomic hydrogen. We locate the density of the transition by computing the equation of state for these two phases and identify the phase transitionmore » order by computing the band gap near the phase transition. These benchmark results show that the phase transition is continuous and occurs at a Wigner-Seitz radius of rs = 2.27(3)a0. As a result, we compare our results to previously reported density functional theory, Hedin s GW approximation, and dynamical mean field theory results.« less

  14. Targeting Low-Energy Transfers to Low Lunar Orbit

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.; Anderson, Rodney L.

    2011-01-01

    A targeting scheme is presented to build trajectories from a specified Earth parking orbit to a specified low lunar orbit via a low-energy transfer and up to two maneuvers. The total transfer delta V (velocity) is characterized as a function of the Earth parking orbit inclination and the departure date for transfers to each given low lunar orbit. The transfer delta V (velocity) cost is characterized for transfers constructed to low lunar polar orbits with any longitude of ascending node and for transfers that arrive at the Moon at any given time during a month.

  15. Modeling and control of distributed energy systems during transition between grid connected and standalone modes

    NASA Astrophysics Data System (ADS)

    Arafat, Md Nayeem

    Distributed generation systems (DGs) have been penetrating into our energy networks with the advancement in the renewable energy sources and energy storage elements. These systems can operate in synchronism with the utility grid referred to as the grid connected (GC) mode of operation, or work independently, referred to as the standalone (SA) mode of operation. There is a need to ensure continuous power flow during transition between GC and SA modes, referred to as the transition mode, in operating DGs. In this dissertation, efficient and effective transition control algorithms are developed for DGs operating either independently or collectively with other units. Three techniques are proposed in this dissertation to manage the proper transition operations. In the first technique, a new control algorithm is proposed for an independent DG which can operate in SA and GC modes. The proposed transition control algorithm ensures low total harmonic distortion (THD) and less voltage fluctuation during mode transitions compared to the other techniques. In the second technique, a transition control is suggested for a collective of DGs operating in a microgrid system architecture to improve the reliability of the system, reduce the cost, and provide better performance. In this technique, one of the DGs in a microgrid system, referred to as a dispatch unit , takes the additional responsibility of mode transitioning to ensure smooth transition and supply/demand balance in the microgrid. In the third technique, an alternative transition technique is proposed through hybridizing the current and droop controllers. The proposed hybrid transition control technique has higher reliability compared to the dispatch unit concept. During the GC mode, the proposed hybrid controller uses current control. During the SA mode, the hybrid controller uses droop control. During the transition mode, both of the controllers participate in formulating the inverter output voltage but with different

  16. Simple solvable energy-landscape model that shows a thermodynamic phase transition and a glass transition.

    PubMed

    Naumis, Gerardo G

    2012-06-01

    When a liquid melt is cooled, a glass or phase transition can be obtained depending on the cooling rate. Yet, this behavior has not been clearly captured in energy-landscape models. Here, a model is provided in which two key ingredients are considered in the landscape, metastable states and their multiplicity. Metastable states are considered as in two level system models. However, their multiplicity and topology allows a phase transition in the thermodynamic limit for slow cooling, while a transition to the glass is obtained for fast cooling. By solving the corresponding master equation, the minimal speed of cooling required to produce the glass is obtained as a function of the distribution of metastable states.

  17. Transition Metal Nitrides for Electrocatalytic Energy Conversion: Opportunities and Challenges.

    PubMed

    Xie, Junfeng; Xie, Yi

    2016-03-01

    Electrocatalytic energy conversion has been considered as one of the most efficient and promising pathways for realizing energy storage and energy utilization in modern society. To improve electrocatalytic reactions, specific catalysts are needed to lower the overpotential. In the search for efficient alternatives to noble metal catalysts, transition metal nitrides have attracted considerable interest due to their high catalytic activity and unique electronic structure. Over the past few decades, numerous nitride-based catalysts have been explored with respect to their ability to drive various electrocatalytic reactions, such as the hydrogen evolution reaction and the oxygen evolution reaction to achieve water splitting and the oxygen reduction reaction coupled with the methanol oxidation reaction to construct fuel cells or rechargeable Li-O2 batteries. This Minireview provides a brief overview of recent progress on electrocatalysts based on transition metal nitrides, and outlines the current challenges and future opportunities. PMID:26494184

  18. Behavior of the low-frequency conductivity of silver iodide nanocomposites in the superionic phase transition region

    NASA Astrophysics Data System (ADS)

    Vergent'ev, T. Yu.; Koroleva, E. Yu.; Kurdyukov, D. A.; Naberezhnov, A. A.; Filimonov, A. V.

    2013-01-01

    The behavior of the specific conductivity of composites based on silver iodide embedded in porous glasses with an average pore diameter of 7 ± 1 nm and in artificial opals with a pore diameter of 40-100 nm has been investigated in the temperature range from 300 to 500 K. It has been shown that a decrease in the characteristic pore size does not lead to a change in the order of the phase transition and that the temperature of the transition to the superionic state of silver iodide in a porous glass and in an opal upon heating is close to the phase transition temperature T c in the bulk material (˜420 K). Upon cooling, the phase transition temperature T c significantly decreases, and the phase transition becomes diffuse. With a decrease in the pore size, the region of the temperature hysteresis of the phase transition increases. The dc conductivities of the composites have been estimated from the impedance diagrams. The temperature dependence of the dc conductivity of both composites has a thermally activated nature, and the slope of the curve σ(1/ T) changes near the phase transition, which indicates a change in the activation energy. The activation energies in the low-temperature and high-temperature phases have been estimated at ˜450-470 and ˜100 meV, respectively. The equivalent electrical circuit describing the charge transfer processes in the studied samples has been proposed.

  19. Quenched disorder forbids discontinuous transitions in nonequilibrium low-dimensional systems.

    PubMed

    Villa Martín, Paula; Bonachela, Juan A; Muñoz, Miguel A

    2014-01-01

    Quenched disorder affects significantly the behavior of phase transitions. The Imry-Ma-Aizenman-Wehr-Berker argument prohibits first-order or discontinuous transitions and their concomitant phase coexistence in low-dimensional equilibrium systems in the presence of random fields. Instead, discontinuous transitions become rounded or even continuous once disorder is introduced. Here we show that phase coexistence and first-order phase transitions are also precluded in nonequilibrium low-dimensional systems with quenched disorder: discontinuous transitions in two-dimensional systems with absorbing states become continuous in the presence of quenched disorder. We also study the universal features of this disorder-induced criticality and find them to be compatible with the universality class of the directed percolation with quenched disorder. Thus, we conclude that first-order transitions do not exist in low-dimensional disordered systems, not even in genuinely nonequilibrium systems with absorbing states.

  20. Energy Transition Initiative, Island Energy Snapshot - Grenada (Fact Sheet)

    SciTech Connect

    Not Available

    2015-03-01

    This profile provides a snapshot of the energy landscape of Grenada - a small island nation consisting of the island of Grenada and six smaller islands in the southeastern Caribbean Sea - three of which are inhabited: Grenada, Carriacou, and Petite Martinique.

  1. High to Low Tide: The High School-University Transition

    ERIC Educational Resources Information Center

    Stone, David C.

    2010-01-01

    In this paper I summarize some key findings from a three-year study of the high school-university transition for students attending a large arts and science faculty, within the context of their first university chemistry course. I then discuss these results within the broader context of research on success in higher education. Final conclusions…

  2. Low temperature magnetic transitions of single crystal HoBi

    SciTech Connect

    Fente, A.; Suderow, H.; Vieira, S.; Nemes, N. M.; Garcia-Hernandez, M.; Budko, Sergei L.; Canfield, Paul C.

    2013-09-04

    We present resistivity, specific heat and magnetization measurements in high quality single crystals of HoBi, with a residual resistivity ratio of 126. We find, from the temperature and field dependence of the magnetization, an antiferromagnetic transition at 5.7 K, which evolves, under magnetic fields, into a series of up to five metamagnetic phases.

  3. Ring Counter Based ATPG for Low Transition Test Pattern Generation

    PubMed Central

    Begam, V. M. Thoulath; Baulkani, S.

    2015-01-01

    In test mode test patterns are applied in random fashion to the circuit under circuit. This increases switching transition between the consecutive test patterns and thereby increases dynamic power dissipation. The proposed ring counter based ATPG reduces vertical switching transitions by inserting test vectors only between the less correlative test patterns. This paper presents the RC-ATPG with an external circuit. The external circuit consists of XOR gates, full adders, and multiplexers. First the total number of transitions between the consecutive test patterns is determined. If it is more, then the external circuit generates and inserts test vectors in between the two test patterns. Test vector insertion increases the correlation between the test patterns and reduces dynamic power dissipation. The results prove that the test patterns generated by the proposed ATPG have fewer transitions than the conventional ATPG. Experimental results based on ISCAS'85 and ISCAS'89 benchmark circuits show 38.5% reduction in the average power and 50% reduction in the peak power attained during testing with a small size decoding logic. PMID:26075295

  4. Low temperature magnetic properties of monoclinic pyrrhotite with particular relevance to the Besnus transition

    NASA Astrophysics Data System (ADS)

    Volk, Michael W. R.; Gilder, Stuart A.; Feinberg, Joshua M.

    2016-10-01

    Monoclinic pyrrhotite (Fe7S8) owes its ferrimagnetism to an ordered array of Fe vacancies. Its magnetic properties change markedly around 30 K, in what is known as the Besnus transition. Plausible explanations for the Besnus transition are either due to changes in crystalline anisotropy from a transformation in crystal symmetry or from the establishment of a two-phase system with magnetic interaction between the two phases. To help resolve this discrepancy, we measured hysteresis loops every 5° and back field curves every 10° in the basal plane of an oriented single crystal of monoclinic pyrrhotite at 300 K and every two kelvin from 50 K through the Besnus transition until 20 K. Between 50 and 30 K, hysteresis loops possess double inflections between crystallographic a-axes and only a single inflection parallel to the a-axes. Magnetization energy calculations and relative differences of the loops show a six-fold symmetry in this temperature range. We propose that the inflections stem from magnetic axis switching, which is both field and temperature dependent, in a manner somewhat analogous to an isotropic point where magnetocrystalline constants change their sign. The Besnus transition is best characterized by changes in magnetic remanence and coercivity over a 6° temperature span (28-34 K) with a maximum rate of change at 30 K. A surprising yet puzzling finding is that the coercivity ratio becomes less than unity below the transition when four-fold symmetry arises. Because the changes in magnetic parameters are linked to the crystal structure, we conclude the Besnus transition owes its origin to a distortion of the crystallographic axes below 30 K rather than an apparition of a two-phase system. An isothermal magnetization of natural pyrrhotite cycled from room temperature to successively lower temperatures through the Besnus transition decreases 2-4 times less than equivalent grain sizes of magnetite, with less than a 10% loss in remanence between 300 K and

  5. Low-bay Lighting Energy Conservation Measures

    2010-12-31

    This software requires inputs of simple low-bay lighting system inventory information and calculates the energy and cost benefits of various retrofit opportunities. This tool includes energy conservation measures for: Low-wattage T8 lighting retrofit, T12 to T8 lighting retrofit, LED Exit signs retrofit, Occupancy sensors, Screw-in lighting retrofit, and central lighting controls. This tool calculates energy savings, demand reduction, cooling load reduction, heating load increases, cost savings, building life cycle costs including: Simple payback, discounted payback,more » net-present value, and savings to investment ratio. In addition this tool also displays the environmental benefits of a project.« less

  6. Competition policy and the transition to a low-carbon, efficient electricity industry

    SciTech Connect

    Moss, Diana L.; Kwoka, John E. Jr.

    2010-08-15

    U.S. industries are facing intense pressures to become more energy efficient. Two concerns are driving this transition. One is the need to lower the carbon footprints of energy-intensive sectors. A second concern is the need to achieve energy security by reducing this country's reliance on foreign sources of energy supplies. (author)

  7. Radiative lifetime and energy of the low-energy isomeric level in 229Th

    NASA Astrophysics Data System (ADS)

    Tkalya, E. V.; Schneider, Christian; Jeet, Justin; Hudson, Eric R.

    2015-11-01

    We estimate the range of the radiative lifetime and energy of the anomalous, low-energy 3 /2+(7.8 ±0.5 eV) state in the 229Th nucleus. Our phenomenological calculations are based on the available experimental data for the intensities of M 1 and E 2 transitions between excited levels of the 229Th nucleus in the Kπ[N nZΛ ] =5 /2+[633 ] and 3 /2+[631 ] rotational bands. We also discuss the influence of certain branching coefficients, which affect the currently accepted measured energy of the isomeric state. From this work, we establish a favored region, 0.66 ×106seV3/ω3≤τ ≤2.2 ×106seV3/ω3 , where the transition lifetime τ as a function of transition energy ω should lie at roughly the 95% confidence level. Together with the result of Beck et al. [LLNL-PROC-415170 (2009)], we establish a favored area where transition lifetime and energy should lie at roughly the 90% confidence level. We also suggest new nuclear physics measurements, which would significantly reduce the ambiguity in the present data.

  8. Negative refraction with low absorption using Raman transitions with magnetoelectric coupling

    SciTech Connect

    Sikes, D. E.; Yavuz, D. D.

    2010-07-15

    We suggest a scheme for obtaining negative refraction that does not require the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same transition frequency. The key idea of the scheme is to obtain a strong electric response by using far-off-resonant Raman transitions. We propose to use a pair of electric-dipole Raman transitions and utilize magneto-electric cross coupling to achieve a negative index of refraction without requiring negative permeability. The interference of the two Raman transitions allows tunable negative refraction with low absorption.

  9. Low to high temperature energy conversion system

    NASA Technical Reports Server (NTRS)

    Miller, C. G. (Inventor)

    1977-01-01

    A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

  10. Biomolecular Dynamics: Order-Disorder Transitions and Energy Landscapes

    PubMed Central

    Whitford, Paul C.; Sanbonmatsu, Karissa Y.; Onuchic, José N.

    2013-01-01

    While the energy landscape theory of protein folding is now a widely accepted view for understanding how relatively-weak molecular interactions lead to rapid and cooperative protein folding, such a framework must be extended to describe the large-scale functional motions observed in molecular machines. In this review, we discuss 1) the development of the energy landscape theory of biomolecular folding, 2) recent advances towards establishing a consistent understanding of folding and function, and 3) emerging themes in the functional motions of enzymes, biomolecular motors, and other biomolecular machines. Recent theoretical, computational, and experimental lines of investigation are providing a very dynamic picture of biomolecular motion. In contrast to earlier ideas, where molecular machines were thought to function similarly to macroscopic machines, with rigid components that move along a few degrees of freedom in a deterministic fashion, biomolecular complexes are only marginally stable. Since the stabilizing contribution of each atomic interaction is on the order of the thermal fluctuations in solution, the rigid body description of molecular function must be revisited. An emerging theme is that functional motions encompass order-disorder transitions and structural flexibility provide significant contributions to the free-energy. In this review, we describe the biological importance of order-disorder transitions and discuss the statistical-mechanical foundation of theoretical approaches that can characterize such transitions. PMID:22790780

  11. Energy neutral and low power wireless communications

    NASA Astrophysics Data System (ADS)

    Orhan, Oner

    Wireless sensor nodes are typically designed to have low cost and small size. These design objectives impose restrictions on the capacity and efficiency of the transceiver components and energy storage units that can be used. As a result, energy becomes a bottleneck and continuous operation of the sensor network requires frequent battery replacements, increasing the maintenance cost. Energy harvesting and energy efficient transceiver architectures are able to overcome these challenges by collecting energy from the environment and utilizing the energy in an intelligent manner. However, due to the nature of the ambient energy sources, the amount of useful energy that can be harvested is limited and unreliable. Consequently, optimal management of the harvested energy and design of low power transceivers pose new challenges for wireless network design and operation. The first part of this dissertation is on energy neutral wireless networking, where optimal transmission schemes under different system setups and objectives are investigated. First, throughput maximization for energy harvesting two-hop networks with decode-and-forward half-duplex relays is studied. For a system with two parallel relays, various combinations of the following four transmission modes are considered: Broadcast from the source, multi-access from the relays, and successive relaying phases I and II. Next, the energy cost of the processing circuitry as well as the transmission energy are taken into account for communication over a broadband fading channel powered by an energy harvesting transmitter. Under this setup, throughput maximization, energy maximization, and transmission completion time minimization problems are studied. Finally, source and channel coding for an energy-limited wireless sensor node is investigated under various energy constraints including energy harvesting, processing and sampling costs. For each objective, optimal transmission policies are formulated as the solutions of a

  12. Phase/Shape Transitions and the Two Neutron Separation Energies

    SciTech Connect

    Zamfir, N. V.; Anghel, Sabina; Cata-Danil, G.

    2008-11-11

    We investigated the evolution of experimental two-neutron separation energies (S{sub 2n}) along the isotopic chains for the even-even nuclei. In order to enhance the sensitivity of our search, differential variation of the S{sub 2n} has been investigated. The emphasis is on finding nonmonotonic behaviors which can be correlated with phase/shape transition. Correlations of the ground state S{sub 2n} values with the excited states energies R{sub 4/2} ratio are also discussed.

  13. Transitions into the negative-energy Dirac continuum

    SciTech Connect

    Krekora, P.; Su, Q.; Grobe, R.

    2004-11-01

    We compare the predictions of the single-particle Dirac equation with quantum field theory for an electron subjected to a space and time dependent field. We demonstrate analytically and numerically that a transition into the negative-energy subspace predicted by the single-particle Dirac equation is directly associated with the degree of suppression of pair-production as described by quantum field theory. We show that the portion of the mathematical wave function that populates the negative-energy states corresponds to the difference between the positron spatial density for systems with and without an electron initially present.

  14. Energy and population: transitional issues and eventual limits.

    PubMed

    Werbos, P J

    1990-08-01

    The implication of population size for US energy requirements is explored in this essay. The basic argument is that the present supply of fuels and energy technologies is not sustainable in the long run, that a wide range of choices is possible when a complete transition is made to sustainable technologies, and that the growth of population and the composition of this growth during the next 30 years are the most serious problems impacting on the achievement of sustainable technology. The importance and future of fuel oil is discussed as well as the transition to sustainable energy supplies: conservation, renewables, nuclear and coal. Dependency on oil can only be changed through time and the infusion of money, but even with these givens, the transition is also dependent on the political and budgetary climate. The race is between crisis and cure. It is argued that the soft energy systems (biomass, solar water heater, wind, hydro, and geothermal energy) along with conservation will increase easily and naturally, but the total potential from these sources amounts to only 10% of the present US energy supply. Conservation offers greater hope because 80% of end-use fossil fuel is used in transportation and industry. Further growth of the population in the US would create a demand to desalinate water, which would increase the demand for energy. A totally soft energy economy is probably not feasible without a drastic reduction in US population. The expected direction is in the increased use of coal, and then nuclear energy. Unfortunately, coal contributes to greenhouse warming, and the supply is limited to 60-100 years. Nuclear proliferation and terrorism is connected to the widespread use of nuclear energy. Some breakthrough technology with cold fusion may offer a safer alternative. High technology renewables such as solar cells can be competitive with nuclear energy, if prices can be kept down. on earth or in space, are being investigated. Exploring a variety of advanced

  15. Energy and population: transitional issues and eventual limits.

    PubMed

    Werbos, P J

    1990-08-01

    The implication of population size for US energy requirements is explored in this essay. The basic argument is that the present supply of fuels and energy technologies is not sustainable in the long run, that a wide range of choices is possible when a complete transition is made to sustainable technologies, and that the growth of population and the composition of this growth during the next 30 years are the most serious problems impacting on the achievement of sustainable technology. The importance and future of fuel oil is discussed as well as the transition to sustainable energy supplies: conservation, renewables, nuclear and coal. Dependency on oil can only be changed through time and the infusion of money, but even with these givens, the transition is also dependent on the political and budgetary climate. The race is between crisis and cure. It is argued that the soft energy systems (biomass, solar water heater, wind, hydro, and geothermal energy) along with conservation will increase easily and naturally, but the total potential from these sources amounts to only 10% of the present US energy supply. Conservation offers greater hope because 80% of end-use fossil fuel is used in transportation and industry. Further growth of the population in the US would create a demand to desalinate water, which would increase the demand for energy. A totally soft energy economy is probably not feasible without a drastic reduction in US population. The expected direction is in the increased use of coal, and then nuclear energy. Unfortunately, coal contributes to greenhouse warming, and the supply is limited to 60-100 years. Nuclear proliferation and terrorism is connected to the widespread use of nuclear energy. Some breakthrough technology with cold fusion may offer a safer alternative. High technology renewables such as solar cells can be competitive with nuclear energy, if prices can be kept down. on earth or in space, are being investigated. Exploring a variety of advanced

  16. Non-resonant electromechanical energy harvesting using inter-ferroelectric phase transitions

    SciTech Connect

    Pérez Moyet, Richard; Rossetti, George A.; Stace, Joseph; Amin, Ahmed; Finkel, Peter

    2015-10-26

    Non-resonant electromechanical energy harvesting is demonstrated under low frequency excitation (<50 Hz) using [110]{sub C}-poled lead indium niobate-lead magnesium niobate-lead titanate relaxor ferroelectric single crystals with compositions near the morphotropic phase boundary. The efficiency of power generation at the stress-induced phase transition between domain-engineered rhombohedral and orthorhombic ferroelectric states is as much as four times greater than is obtained in the linear piezoelectric regime under identical measurement conditions but during loading below the coercive stress of the phase change. The phase transition mode of electromechanical transduction holds potential for non-resonant energy harvesting from low-frequency vibrations and does not require mechanical frequency up-conversion.

  17. Measurements in a Transitional Boundary Layer Under Low-Pressure Turbine Airfoil Conditions

    NASA Technical Reports Server (NTRS)

    Simon, Terrence W.; Qiu, Songgang; Yuan, Kebiao; Ashpis, David (Technical Monitor); Simon, Fred (Technical Monitor)

    2000-01-01

    This report presents the results of an experimental study of transition from laminar to turbulent flow in boundary layers or in shear layers over separation zones on a convex-curved surface which simulates the suction surface of a low-pressure turbine airfoil. Flows with various free-stream turbulence intensity (FSTI) values (0.5%, 2.5% and 10%), and various Reynolds numbers (50,000, 100,000 200,000 and 300,000) are investigated. Reynold numbers in the present study are based on suction surface length and passage exit mean velocity. Flow separation followed by transition within the separated flow region is observed for the lower-Re cases at each of the FSTI levels. At the highest Reynolds numbers and at elevated FSn, transition of the attached boundary layer begins before separation, and the separation zone is small. Transition proceeds in the shear layer over the separation bubble. For both the transitional boundary layer and the transitional shear layer, mean velocity, turbulence intensity and intermittency (the fraction of the time the flow is turbulent) distributions are presented. The present data are compared to published distribution models for bypass transition, intermittency distribution through transition, transition start position, and transition length. A model developed for transition of separated flows is shown to adequately predict the location of the beginning of transition, for these cases, and a model developed for transitional boundary layer flows seems to adequately predict the path of intermittency through transition when the transition start and end are known. These results are useful for the design of low-pressure turbine stages which are known to operate under conditions replicated by these tests.

  18. Low barrier kinetics: dependence on observables and free energy surface.

    PubMed

    Ma, Hairong; Gruebele, Martin

    2006-01-30

    Dynamics on free energy surfaces with high activation barriers are usually treated by few-state kinetics models, yielding characteristic rate coefficients and amplitudes depending on the connectivity of the states. When the barriers are low (< 3 kT), the assumption of instantaneous equilibration of the transition state, and hence, the few-state kinetics treatment, break down. Langevin dynamics is used here to explore the characteristic trends that occur in such cases, as a function of barrier height, number of barriers, dimensionality of the free energy surface, and switching functions that describe how spectroscopic probes vary from reactant to product. The result is a systematic phenomenological description of low barrier kinetics and dynamics.

  19. Photon strength and the low-energy enhancement

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Bernstein, L. A.; Krtička, M.; Bleuel, D. L.; Allmond, J. M.; Basunia, M. S.; Burke, J. T.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.

    2014-08-01

    Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in 95Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection and extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to 95Mo photon strength function data measured at the University of Oslo.

  20. Photon strength and the low-energy enhancement

    SciTech Connect

    Wiedeking, M.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Hatarik, R.; Lesher, S. R.; Scielzo, N. D.; Krtička, M.; Allmond, J. M.; Basunia, M. S.; Fallon, P.; Firestone, R. B.; Lake, P. T.; Lee, I-Y.; Paschalis, S.; Petri, M.; Phair, L.; Goldblum, B. L.

    2014-08-14

    Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in {sup 95}Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection and extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to {sup 95}Mo photon strength function data measured at the University of Oslo.

  1. The Telescope Array's Low Energy Extension: TALE

    NASA Astrophysics Data System (ADS)

    Matthews, John

    2009-05-01

    A great deal of information about the sources of ultra high energy cosmic rays exists encoded in the energy spectrum. There are three spectral features in the ultra high energy regime (the second knee, the ankle, and the GZK cut-off). An important composition change also occurs in this energy range. The Telescope Array (TA) is a large area ultra high energy cosmic ray observatory built and operated by groups from the US, Japan, Korea, and Russia. The existing part of the Telescope Array already has good efficiency above the ankle (˜10^18.5 eV). These detectors are already in the field collecting data. The TA Low Energy Extension (TALE) refers to the detectors devoted to the ``low energy'' portion of the spectrum - 10^16.5 - 10^19 eV. The aim of TA/TALE is to understand the origin of cosmic rays and to study their composition over a broad energy range. We will introduce the detector components and discuss the opportunities.

  2. Low Energy Ion-Molecule Reactions

    SciTech Connect

    James M. Farrar

    2004-05-01

    This objective of this project is to study the dynamics of the interactions of low energy ions important in combustion with small molecules in the gas phase and with liquid hydrocarbon surfaces. The first of these topics is a long-standing project in our laboratory devoted to probing the key features of potential energy surfaces that control chemical reactivity. The project provides detailed information on the utilization of specific forms of incident energy, the role of preferred reagent geometries, and the disposal of total reaction energy into product degrees of freedom. We employ crossed molecular beam methods under single collision conditions, at collision energies from below one eV to several eV, to probe potential surfaces over a broad range of distances and interaction energies. These studies allow us to test and validate dynamical models describing chemical reactivity. Measurements of energy and angular distributions of the reaction products with vibrational state resolution provide the key data for these studies. We employ the crossed beam low energy mass spectrometry methods that we have developed over the last several years.

  3. PHYSICS WITH ULTRA-LOW ENERGY ANTIPROTONS

    SciTech Connect

    M. HOLZSCHEITER

    2001-02-01

    In this report the author describes the current status of the antiproton deceleration (AD) facility at CERN, and highlights the physics program with ultra-low energy antiproton at this installation. He also comments on future possibilities provided higher intensity antiproton beams become available at Fermilab, and review possibilities for initial experiments using direct degrading of high energy antiprotons in material has been developed and proven at CERN.

  4. A phase transition in energy-filtered RNA secondary structures.

    PubMed

    Han, Hillary S W; Reidys, Christian M

    2012-10-01

    In this article we study the effect of energy parameters on minimum free energy (mfe) RNA secondary structures. Employing a simplified combinatorial energy model that is only dependent on the diagram representation and is not sequence-specific, we prove the following dichotomy result. Mfe structures derived via the Turner energy parameters contain only finitely many complex irreducible substructures, and just minor parameter changes produce a class of mfe structures that contain a large number of small irreducibles. We localize the exact point at which the distribution of irreducibles experiences this phase transition from a discrete limit to a central limit distribution and, subsequently, put our result into the context of quantifying the effect of sparsification of the folding of these respective mfe structures. We show that the sparsification of realistic mfe structures leads to a constant time and space reduction, and that the sparsification of the folding of structures with modified parameters leads to a linear time and space reduction. We, furthermore, identify the limit distribution at the phase transition as a Rayleigh distribution.

  5. Nanostructured transition metal oxides for energy storage and conversion

    NASA Astrophysics Data System (ADS)

    Li, Qiang

    Lithium-ion batteries, supercapacitors and photovoltaic devices have been widely considered as the three major promising alternatives of fossil fuels facing upcoming depletion to power the 21th century. The conventional film configuration of electrochemical electrodes hardly fulfills the high energy and efficiency requirements because heavy electroactive material deposition restricts ion diffusion path, and lowers power density and fault tolerance. In this thesis, I demonstrate that novel nanoarchitectured transition metal oxides (TMOs), e.g. MnO2, V2O 5, and ZnO, and their relevant nanocomposites were designed, fabricated and assembled into devices to deliver superior electrochemical performances such as high energy and power densities, and rate capacity. These improvements could be attributed to the significant enhancement of surface area, shortened ion diffusion distances and facile penetration of electrolyte solution into open structures of networks as well as to the pseudocapacitance domination. The utilization of ForcespinningRTM, a newly developed nanofiber processing technology, for large-scale energy storage and conversion applications is emphasized. This process simplifies the tedious multi-step hybridization synthesis and facilitates the contradiction between the micro-batch production and the ease of large-scale manufacturing. Key Words: Transition metal oxides, energy storage and conversion, ForcespinningRTM, pseudocapacitance domination, high rate capacity

  6. Many-body energy localization transition in periodically driven systems

    SciTech Connect

    D’Alessio, Luca; Polkovnikov, Anatoli

    2013-06-15

    According to the second law of thermodynamics the total entropy of a system is increased during almost any dynamical process. The positivity of the specific heat implies that the entropy increase is associated with heating. This is generally true both at the single particle level, like in the Fermi acceleration mechanism of charged particles reflected by magnetic mirrors, and for complex systems in everyday devices. Notable exceptions are known in noninteracting systems of particles moving in periodic potentials. Here the phenomenon of dynamical localization can prevent heating beyond certain threshold. The dynamical localization is known to occur both at classical (Fermi–Ulam model) and at quantum levels (kicked rotor). However, it was believed that driven ergodic systems will always heat without bound. Here, on the contrary, we report strong evidence of dynamical localization transition in both classical and quantum periodically driven ergodic systems in the thermodynamic limit. This phenomenon is reminiscent of many-body localization in energy space. -- Highlights: •A dynamical localization transition in periodically driven ergodic systems is found. •This phenomenon is reminiscent of many-body localization in energy space. •Our results are valid for classical and quantum systems in the thermodynamic limit. •At critical frequency, the short time expansion for the evolution operator breaks down. •The transition is associated to a divergent time scale.

  7. Performance monitoring of low energy house, Macclesfield

    NASA Astrophysics Data System (ADS)

    Stephen, F. R.

    1980-01-01

    The monitoring of the energy balance of a very well insulated low-energy house in Macclesfield, England is discussed. The house is an existing dwelling which had been converted into a low-energy-requiring house by the reduction of heat loss through a high level of thermal insulation and the collection of solar energy by a water cascade solar panel with warm water storage. Measurements of house temperatures, radiation, off-peak electricity consumption and hot water and heating using were performed from January to August, 1978 and reveal that the house used less than 22,000 kWh electricity during that period, compared to 55,000 kWh expected if the house had been constructed to average insulation levels. Solar energy is found to contribute only 2% of house energy requirements, with the use of a heat pump combined with the solar panel leading to greater efficiency and thus utilization. In addition, the large thermal mass and good insulation are found to improve comfort by reducing temperature fluctuations, and the ventilation and low-temperature water return system employed provided satisfactory results.

  8. Developing and Using Green Skills for the Transition to a Low Carbon Economy

    ERIC Educational Resources Information Center

    Brown, Mike

    2015-01-01

    One of the strategies being advocated in response to climate change is the need to transition to a low carbon economy. Current projections show that within this transition, new jobs will be created, some eliminated and most others subjected to change. This article reports findings from interviews with a selection of twenty participants who are…

  9. Energy-management guidelines for rail-transit systems. Executive summary. Final report, 9 July 1984-30 October 1986

    SciTech Connect

    Uher, R.A.; Sharma, O.N.

    1986-09-01

    The cost of electricity is a significant portion of the operating costs of rail-transit systems. The impact of increasing energy costs is felt by those systems presently in operation and will be felt by those in the planning or construction phases. Concerned by rising energy costs, managers of several rail-transit authorities have established energy-management programs. The objectives of these programs are energy cost reduction and improved energy efficiency. Both goals enhance rail-transit productivity. As a rule, energy management can foster its largest payoff when it is initiated during the design and construction phase of a rail-transit system. The high dollar savings occur because low-energy-cost technology and operating practices can be engineered into the system at the outset. However, changes in technology and operations of present transit systems can also reduce the electric bill. Reduction of energy cost can be achieved through energy conservation, load management, and power-rate intervention. These guidelines describe the tools and methodologies for assessing energy-conservation strategies and power-rate-structure modifications.

  10. Low energy signatures of nonlocal field theories

    NASA Astrophysics Data System (ADS)

    Belenchia, Alessio; Benincasa, Dionigi M. T.; Martín-Martínez, Eduardo; Saravani, Mehdi

    2016-09-01

    The response of inertial particle detectors coupled to a scalar field satisfying nonlocal dynamics described by nonanalytic functions of the d'Alembertian operator □ is studied. We show that spontaneous emission processes of a low energy particle detector are very sensitive to high-energy nonlocality scales. This allows us to suggest a nuclear physics experiment (˜MeV energy scales) that outperforms the sensitivity of LHC experiments by many orders of magnitude. This may have implications for the falsifiability of theoretical proposals of quantum gravity.

  11. Energy levels and radiative rates for transitions in Ga XXIV

    SciTech Connect

    El-Sayed, Fatma

    2012-07-15

    Energy levels, transition probabilities, oscillator strengths, line strengths, and lifetimes have been calculated for Oxygen-like Gallium, Ga XXIV. The configurations 2s{sup 2}2p{sup 4}, 2s2p{sup 5}, 2p{sup 6}, 2s2p{sup 4}3 Script-Small-L , 2s{sup 2}2p{sup 3}3 Script-Small-L , and 2p{sup 5}3 Script-Small-L were used in calculations and 226 fine-structure levels were obtained. The fully relativistic GRASP code has been adopted, and results are reported for all electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 226 levels of Ga XXIV, belonging to the n{<=}3 configurations. Comparisons have been made with earlier available theoretical and experimental results.

  12. IBS and Potential Luminosity Improvement for RHIC Operation Below Transition Energy

    SciTech Connect

    Fedotov,A.

    2009-01-02

    There is a strong interest in low-energy RHIC operations in the single-beam total energy range of 2.5-25 GeV/nucleon [1-3]. Collisions in this energy range, much of which is below nominal RHIC injection energy, will help to answer one of the key questions in the field of QeD about the existence and location of a critical point on the QCD phase diagram [4]. There have been several short test runs during 2006-2008 RHIC operations to evaluate RHIC operational challenges at these low energies [5]. Beam lifetimes observed during the test runs were limited by machine nonlinearities. This performance limit can be improved with sufficient machine tuning. The next luminosity limitation comes from transverse and longitudinal Intra-beam Scattering (IBS), and ultimately from the space-charge limit. Detailed discussion of limiting beam dynamics effects and possible luminosity improvement with electron cooling can be found in Refs. [6-8]. For low-energy RHIC operation, particle losses from the RF bucket are of particular concern since the longitudinal beam size is comparable to the existing RF bucket at low energies. However, operation below transition energy allows us to exploit an Intra-beam Scattering (IBS) feature that drives the transverse and longitudinal beam temperatures towards equilibrium by minimizing the longitudinal diffusion rate using a high RF voltage. Simulation studies were performed with the goal to understand whether one can use this feature of IBS to improve luminosity of RHIC collider at low-energies. This Note presents results of simulations which show that additional luminosity improvement for low-energy RHIC project may be possible with high RF voltage from a 56 MHz superconducting RF cavity that is presently under development for RHIC.

  13. A rocky planet transiting a nearby low-mass star.

    PubMed

    Berta-Thompson, Zachory K; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R; Dittmann, Jason A; Astudillo-Defru, Nicola; Bonfils, Xavier; Gillon, Michaël; Jehin, Emmanuël; Stark, Antony A; Stalder, Brian; Bouchy, Francois; Delfosse, Xavier; Forveille, Thierry; Lovis, Christophe; Mayor, Michel; Neves, Vasco; Pepe, Francesco; Santos, Nuno C; Udry, Stéphane; Wünsche, Anaël

    2015-11-12

    M-dwarf stars--hydrogen-burning stars that are smaller than 60 per cent of the size of the Sun--are the most common class of star in our Galaxy and outnumber Sun-like stars by a ratio of 12:1. Recent results have shown that M dwarfs host Earth-sized planets in great numbers: the average number of M-dwarf planets that are between 0.5 to 1.5 times the size of Earth is at least 1.4 per star. The nearest such planets known to transit their star are 39 parsecs away, too distant for detailed follow-up observations to measure the planetary masses or to study their atmospheres. Here we report observations of GJ 1132b, a planet with a size of 1.2 Earth radii that is transiting a small star 12 parsecs away. Our Doppler mass measurement of GJ 1132b yields a density consistent with an Earth-like bulk composition, similar to the compositions of the six known exoplanets with masses less than six times that of the Earth and precisely measured densities. Receiving 19 times more stellar radiation than the Earth, the planet is too hot to be habitable but is cool enough to support a substantial atmosphere, one that has probably been considerably depleted of hydrogen. Because the host star is nearby and only 21 per cent the radius of the Sun, existing and upcoming telescopes will be able to observe the composition and dynamics of the planetary atmosphere.

  14. A rocky planet transiting a nearby low-mass star.

    PubMed

    Berta-Thompson, Zachory K; Irwin, Jonathan; Charbonneau, David; Newton, Elisabeth R; Dittmann, Jason A; Astudillo-Defru, Nicola; Bonfils, Xavier; Gillon, Michaël; Jehin, Emmanuël; Stark, Antony A; Stalder, Brian; Bouchy, Francois; Delfosse, Xavier; Forveille, Thierry; Lovis, Christophe; Mayor, Michel; Neves, Vasco; Pepe, Francesco; Santos, Nuno C; Udry, Stéphane; Wünsche, Anaël

    2015-11-12

    M-dwarf stars--hydrogen-burning stars that are smaller than 60 per cent of the size of the Sun--are the most common class of star in our Galaxy and outnumber Sun-like stars by a ratio of 12:1. Recent results have shown that M dwarfs host Earth-sized planets in great numbers: the average number of M-dwarf planets that are between 0.5 to 1.5 times the size of Earth is at least 1.4 per star. The nearest such planets known to transit their star are 39 parsecs away, too distant for detailed follow-up observations to measure the planetary masses or to study their atmospheres. Here we report observations of GJ 1132b, a planet with a size of 1.2 Earth radii that is transiting a small star 12 parsecs away. Our Doppler mass measurement of GJ 1132b yields a density consistent with an Earth-like bulk composition, similar to the compositions of the six known exoplanets with masses less than six times that of the Earth and precisely measured densities. Receiving 19 times more stellar radiation than the Earth, the planet is too hot to be habitable but is cool enough to support a substantial atmosphere, one that has probably been considerably depleted of hydrogen. Because the host star is nearby and only 21 per cent the radius of the Sun, existing and upcoming telescopes will be able to observe the composition and dynamics of the planetary atmosphere. PMID:26560298

  15. Inelastic pion scattering by /sup 13/C at low energies

    SciTech Connect

    Mitchell, J.H.

    1987-03-01

    Angular distributions for inelastically scattered pions were obtained for several states in /sup 13/C at an incident energy of 65 MeV. The data include results from both ..pi../sup +/ and ..pi../sup -/ measurements. In addition, ..pi../sup -/ measurements were made at T/sub ..pi../ = 50 MeV at one angle to give a two point fixed-q excitation function. The data are compared to theory and the data of others. As might be expected, medium corrections are shown to be considerably more important at low energies than at resonance. This is true for inelastic transitions of multipolarity 0,2 and 3. Parameters derived from an analysis of elastic pion scattering and SCX data also provide an adequate description of the inelastic transitions. The charge asymmetry in the cross sections for the 9/2/sup +/ state that was seen at resonance persists at these energies. This result is consistent with an impulse approximation treatment of the spin-flip amplitude. This is true even though the incoming energy of the pions is far below the range where the validity of an impulse treatment is expected. 65 refs., 45 figs.

  16. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Carl R. Brune; Steven M. Grimes

    2010-01-13

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between March 1, 2006 and October 31, 2009 which were supported by U.S. DOE grant number DE-FG52-06NA26187.

  17. Parity violation in low-energy

    SciTech Connect

    Martin Savage

    2001-12-01

    Parity violation in low-energy nuclear observables is included in the pionless effective field theory. The model-independent relation between the parity-violating asymmetry in polarized np -> d gamma and the non-nucleon part of the deuteron anapole moment is discussed. The asymmetry in np -> d gamma computed with KSW power-counting, and recently criticized by Desplanques, is discussed.

  18. Low-power stimulated emission nuclear quadrupole resonance detection system utilizing Rabi transitions

    NASA Astrophysics Data System (ADS)

    Apostolos, John; Mouyos, William; Feng, Judy; Chase, Walter

    2013-06-01

    The application of CW radar techniques to Nuclear Quadrupole Resonance (NQR) detection of nitrogen based explosives and chlorine based narcotics enables the use of low power levels, in the range of 10's of watts, to yield high signal strengths. By utilizing Rabi transitions the nucleus oscillates between states one and two under the time dependent incident electromagnetic field and alternately absorbs energy from the incident field while emitting coherent energy via stimulated emission. Through the application of a cancellation algorithm the incident field is eliminated from the NQR response, allowing the receive signal to be measured while transmitting. The response signal is processed using matched filters of the NQR response which enables the direct detection of explosives. This technology has applicability to the direct detection of explosives and narcotics for security screening, all at safe low power levels, opposed to the current XRay and Millimeter wave screening systems that detect objects that may contain explosives and utilize high power. The quantum mechanics theoretical basis for the approach and an application for a system for security screening are described with empirical results presented to show the effects observed.

  19. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  20. Measurements in Separated and Transitional Boundary Layers Under Low-Pressure Turbine Airfoil Conditions

    NASA Technical Reports Server (NTRS)

    Volino, Ralph J.; Hultgren, Lennart .

    2000-01-01

    Detailed velocity measurements were made along a flat plate subject to the same dimensionless pressure gradient as the suction side of a modern low-pressure turbine airfoil. Reynolds numbers based on wetted plate length and nominal exit velocity were varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low and high inlet free-stream turbulence intensities (0.2% and 7%) were set using passive grids. The location of boundary-layer separation does not depend strongly on the free-stream turbulence level or Reynolds number, as long as the boundary layer remains non-turbulent prior to separation. Strong acceleration prevents transition on the upstream part of the plate in all cases. Both free-stream turbulence and Reynolds number have strong effects on transition in the adverse pressure gradient region. Under low free-stream turbulence conditions transition is induced by instability waves in the shear layer of the separation bubble. Reattachment generally occurs at the transition start. At Re = 50,000 the separation bubble does not close before the trailing edge of the modeled airfoil. At higher Re, transition moves upstream, and the boundary layer reattaches. With high free-stream turbulence levels, transition appears to occur in a bypass mode, similar to that in attached boundary layers. Transition moves upstream, resulting in shorter separation regions. At Re above 200,000, transition begins before separation. Mean velocity, turbulence and intermittency profiles are presented.

  1. Global Warming and Energy Transition: A Public Policy Imperative

    NASA Astrophysics Data System (ADS)

    Stone, G. T.

    2006-12-01

    The historic transition from fossil fuels to alternative energy resources has begun. This development is commonly attributed to increasing energy costs and the need for energy security. Looming ever larger, however, is the issue that will soon drive the third energy revolution: global warming. A preponderance of evidence documents accelerating warming, enlarging impacts, and human causes -- principally combustion of fossil fuels. The carbon dioxide (C02) content of Earth's atmosphere has increased more than 35 percent since the beginning of the industrial revolution and is the highest in 650,000 years. This dramatic rise of C02 and attendant positive feedbacks are already forcing significant impacts worldwide. These include atmospheric warming with shifting climatic and habitat zones, spreading tropical disease, and more extreme weather events; rapid ice loss at high latitude and high altitude; ocean warming and acidification with coral reef bleaching and intensifying tropical storms; rising sea level; and accelerating extinction rates. The 2007 draft report of the Intergovernmental Panel on Climate Change (IPCC) predicts greater warming than in previous models. A tipping point to abrupt climate change may be imminent. It is incumbent upon geoscientists and geoscience educators to assume leadership in addressing this challenge through public outreach and general education. The following topics should be integrated into all appropriate courses: the evidence of global warming and its causes; observed present and predicted future impacts of global warming; mitigation and adaptation strategies; and implications for energy policies and economic opportunities. New entry-level science and general education courses -- such as Climate Change Fundamentals and Energy in Nature, Technology, and Society -- are proving to be effective should be widely developed In addition, by workshops and presentations to civic and business organizations and by demonstrated examples of

  2. Development of Low Energy Gap and Fully Regioregular Polythienylenevinylene Derivative

    DOE PAGES

    David, Tanya M. S.; Zhang, Cheng; Sun, Sam-Shajing

    2014-01-01

    Low energy gap and fully regioregular conjugated polymers find its wide use in solar energy conversion applications. This paper will first briefly review this type of polymers and also report synthesis and characterization of a specific example new polymer, a low energy gap, fully regioregular, terminal functionalized, and processable conjugated polymer poly-(3-dodecyloxy-2,5-thienylene vinylene) or PDDTV. The polymer exhibited an optical energy gap of 1.46 eV based on the UV-vis-NIR absorption spectrum. The electrochemically measured highest occupied molecular orbital (HOMO) level is −4.79 eV, resulting in the lowest unoccupied molecular orbital (LUMO) level of −3.33 eV based on optical energy gap. The polymer wasmore » synthesized via Horner-Emmons condensation and is fairly soluble in common organic solvents such as tetrahydrofuran and chloroform with gentle heating. DSC showed two endothermic peaks at 67°C and 227°C that can be attributed to transitions between crystalline and liquid states. The polymer is thermally stable up to about 300°C. This polymer appears very promising for cost-effective solar cell applications.« less

  3. Steering quantum transitions between three crossing energy levels

    SciTech Connect

    Ivanov, S. S.; Vitanov, N. V.

    2008-02-15

    We calculate the propagator and the transition probabilities for a coherently driven three-state quantum system. The energies of the three states change linearly in time, whereas the interactions between them are pulse shaped. We derive a highly accurate analytic approximation by assuming independent pairwise Landau-Zener transitions occurring instantly at the relevant avoided crossings, and adiabatic evolution elsewhere. Quantum interferences are identified, which occur due to different possible evolution paths in Hilbert space between an initial and a final state. A detailed comparison with numerical results for Gaussian-shaped pulses demonstrates a remarkable accuracy of the analytic approximation. We use the analytic results to derive estimates for the half-width of the excitation profile, and for the parameters required for creation of a maximally coherent superposition of the three states. These results are of potential interest in ladder climbing in alkali-metal atoms by chirped laser pulses, in quantum rotors, in transitions between Zeeman sublevels of a J=1 level in a magnetic field, and in control of entanglement of a pair of spin-1/2 particles. The results for the three-state system can be generalized, without essential difficulties, to higher dimensions.

  4. Low energy ion-molecule reactions

    SciTech Connect

    Farrar, J.M.

    1993-12-01

    This project is concerned with elucidating the dynamics of elementary ion-molecule reactions at collision energies near and below 1 eV. From measurements of the angular and energy distributions of the reaction products, one can infer intimathe details about the nature of collisions leading to chemical reaction, the geometries and lifetimes of intermediate complexes that govern the reaction dynamics, and the collision energy dependence of these dynamical features. The author employs crossed-beam low energy mass spectrometry technology developed over the last several years, with the focus of current research on proton transfer and hydrogen atom transfer reactions of te O{sup {minus}} ion with species such as HF, H{sub 2}O, and NH{sub 3}.

  5. Low-energy neutral-atom spectrometer

    SciTech Connect

    Voss, D.E.; Cohen, S.A.

    1982-04-01

    The design, calibration, and performance of a low energy neutral atom spectrometer are described. Time-of-flight analysis is used to measure the energy spectrum of charge-exchange deuterium atoms emitted from the PLT tokamak plasma in the energy range from 20 to 1000 eV. The neutral outflux is gated on a 1 ..mu..sec time scale by a slotted rotating chopper disc, supported against gravity in vacuum by magnetic levitation, and is detected by secondary electron emission from a Cu-Be plate. The energy dependent detection efficiency has been measured in particle beam experiments and on the tokamak so that the diagnostic is absolutely calibrated, allowing quantitative particle fluxes to be determined with 200 ..mu..sec time resolution. In addition to its present application as a plasma diagnostic, the instrument is capable of making a wide variety of measurements relevant to atomic and surface physics.

  6. Low-to-High Confinement Transition Mediated by Turbulence Radial Wave Number Spectral Shift in a Fusion Plasma.

    PubMed

    Xu, G S; Wan, B N; Wang, H Q; Guo, H Y; Naulin, V; Rasmussen, J Juul; Nielsen, A H; Wu, X Q; Yan, N; Chen, L; Shao, L M; Chen, R; Wang, L; Zhang, W

    2016-03-01

    A new model for the low-to-high (L-H) confinement transition has been developed based on a new paradigm for turbulence suppression by velocity shear [G. M. Staebler et al., Phys. Rev. Lett. 110, 055003 (2013)]. The model indicates that the L-H transition can be mediated by a shift in the radial wave number spectrum of turbulence, as evidenced here, for the first time, by the direct observation of a turbulence radial wave number spectral shift and turbulence structure tilting prior to the L-H transition at tokamak edge by direct probing. This new mechanism does not require a pretransition overshoot in the turbulent Reynolds stress, shunting turbulence energy to zonal flows for turbulence suppression as demonstrated in the experiment.

  7. Low-to-High Confinement Transition Mediated by Turbulence Radial Wave Number Spectral Shift in a Fusion Plasma

    NASA Astrophysics Data System (ADS)

    Xu, G. S.; Wan, B. N.; Wang, H. Q.; Guo, H. Y.; Naulin, V.; Rasmussen, J. Juul; Nielsen, A. H.; Wu, X. Q.; Yan, N.; Chen, L.; Shao, L. M.; Chen, R.; Wang, L.; Zhang, W.

    2016-03-01

    A new model for the low-to-high (L -H ) confinement transition has been developed based on a new paradigm for turbulence suppression by velocity shear [G. M. Staebler et al., Phys. Rev. Lett. 110, 055003 (2013)]. The model indicates that the L -H transition can be mediated by a shift in the radial wave number spectrum of turbulence, as evidenced here, for the first time, by the direct observation of a turbulence radial wave number spectral shift and turbulence structure tilting prior to the L -H transition at tokamak edge by direct probing. This new mechanism does not require a pretransition overshoot in the turbulent Reynolds stress, shunting turbulence energy to zonal flows for turbulence suppression as demonstrated in the experiment.

  8. New Cooperative Mechanisms of Low-Energy Nuclear Reactions Using Super Low-Energy External Field

    NASA Astrophysics Data System (ADS)

    Gareev, F. A.; Zhidkova, I. E.

    We propose a new mechanism of LENR: cooperative processes in the whole system, nuclei + atoms + condensed matter, can occur at a smaller threshold energies than the corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low-energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution of inner energy of the whole system.

  9. Transition Metal Carbides and Nitrides in Energy Storage and Conversion

    PubMed Central

    Zhong, Yu; Shi, Fan; Zhan, Jiye; Tu, Jiangping

    2016-01-01

    High‐performance electrode materials are the key to advances in the areas of energy conversion and storage (e.g., fuel cells and batteries). In this Review, recent progress in the synthesis and electrochemical application of transition metal carbides (TMCs) and nitrides (TMNs) for energy storage and conversion is summarized. Their electrochemical properties in Li‐ion and Na‐ion batteries as well as in supercapacitors, and electrocatalytic reactions (oxygen evolution and reduction reactions, and hydrogen evolution reaction) are discussed in association with their crystal structure/morphology/composition. Advantages and benefits of nanostructuring (e.g., 2D MXenes) are highlighted. Prospects of future research trends in rational design of high‐performance TMCs and TMNs electrodes are provided at the end. PMID:27812464

  10. Low Energy Nuclear Reactions: 2007 Update

    NASA Astrophysics Data System (ADS)

    Krivit, Steven B.

    2007-03-01

    This paper presents an overview of low energy nuclear reactions, a subset of the field of condensed matter nuclear science. Condensed matter nuclear science studies nuclear effects in and/or on condensed matter, including low energy nuclear reactions, an entirely new branch of science that gained widespread attention and notoriety beginning in 1989 with the announcement of a previously unrecognized source of energy by Martin Fleischmann and Stanley Pons that came to be known as cold fusion. Two branches of LENR are recognized. The first includes a set of reactions like those observed by Fleischmann and Pons that use palladium and deuterium and yield excess heat and helium-4. Numerous mechanisms have been proposed to explain these reactions, however there is no consensus for, or general acceptance of, any of the theories. The claim of fusion is still considered speculative and, as such, is not an ideal term for this work. The other branch is a wide assortment of nuclear reactions that may occur with either hydrogen or deuterium. Anomalous nuclear transmutations are reported that involve light as well as heavy elements. The significant questions that face this field of research are: 1) Are LENRs a genuine nuclear reaction? 2) If so, is there a release of excess energy? 3) If there is, is the energy release cost-effective?

  11. Pressure-driven high to low spin transition in the bimetallic quantum magnet [Ru2(O2CMe)4]3[Cr(CN)6

    SciTech Connect

    O'Neal, K. R.; Liu, Z.; Miller, Joel S.; Fishman, Randy Scott; Musfeldt, J. L.

    2014-01-01

    Synchrotron-based infrared and Raman spectroscopies were brought together with diamond anvil cell techniques and an analysis of the magnetic properties to investigate the pressure-induced high low spin transition in [Ru2(O2CMe)4]3[Cr(CN)6]. The extended nature of the diruthenium wavefunction combined with coupling to chromium-related local lattice distortions changes the relative energies of the and orbitals and drives the high low spin transition on the mixed-valence diruthenium complex. This is a rare example of an externally controlled metamagnetic transition in which both spin-orbit and spin-lattice interactions contribute to the mechanism.

  12. FLSR - The Frankfurt low energy storage ring

    NASA Astrophysics Data System (ADS)

    Stiebing, K. E.; Alexandrov, V.; Dörner, R.; Enz, S.; Kazarinov, N. Yu.; Kruppi, T.; Schempp, A.; Schmidt Böcking, H.; Völp, M.; Ziel, P.; Dworak, M.; Dilfer, W.

    2010-02-01

    An electrostatic storage ring for low-energy ions with a design energy of 50 keV is presently being set up at the Institut für Kernphysik der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany (IKF). This new device will provide a basis for new experiments on the dynamics of ionic and molecular collisions, as well as for high precision and time resolved laser spectroscopy. In this article, the design parameters of this instrument are reported.

  13. Low-Energy Enhancement in the Photon Strength of Mo95

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Bernstein, L. A.; Krtička, M.; Bleuel, D. L.; Allmond, J. M.; Basunia, M. S.; Burke, J. T.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.

    2012-04-01

    A new experimental technique is presented using proton-γ-γ correlations from Mo94(d,p)Mo95 reactions which allows for the model-independent extraction of the photon strength function at various excitation energies using primary γ-ray decay from the quasicontinuum to individual low-lying levels. Detected particle energies provide the entrance excitation energies into the residual nucleus while γ-ray transitions from low-lying levels specify the discrete states being fed. Results strongly support the existence of the previously reported low-energy enhancement in the photon strength function.

  14. [Energy cost of running during a specific transition in duathlon].

    PubMed

    Vallier, Jean-Marc; Mazure, Cyrille; Hausswirth, Christophe; Bernard, Thierry; Brisswalter, Jeanick

    2003-10-01

    The aim of the present study was to investigate the variability of the energy cost of running (Cr) during a simulated duathlon performed in outdoor conditions by elite duathletes. This duathlon consisted of 5 km of running, 30 km of cycling, and 5 km of running. The main result was the lack of significant difference in Cr between the two running bouts (210 +/- 10 mL d'O2.km-1.kg-1 vs. 217 +/- 10 mL d'O2.km-1.kg-1). This result is different from those observed during a triathlon, where an increase of energy cost of running bout has been reported. Furthermore, during a short-distance duathlon performed by well-trained subjects, none of the physiological (ventilation alteration, metabolic changes, or dehydration) or biomechanical factors that are classically evoked in triathlon research to explain Cr variability seem to be affected by the run-cycle-run transition. These results seem to minimize the negative effect of the cycle-to-run transition during a short-duration event in well-trained subjects. PMID:14710519

  15. Transition properties of low-lying states in atomic indium

    SciTech Connect

    Sahoo, B. K.; Das, B. P.

    2011-07-15

    We present here the results of our relativistic many-body calculations of various properties of the first six low-lying excited states of indium. The calculations were performed using the relativistic coupled-cluster method in the framework of the singles, doubles, and partial triples approximation. The lifetime of the [4p{sup 6}]5s{sup 2}5p{sub 3/2} state in this atom is determined. Our results could be used to shed light on the reliability of the lifetime measurements of the excited states of atomic indium that we have considered in the present work.

  16. Durable, Low-Surface-Energy Treatments

    NASA Technical Reports Server (NTRS)

    Willis, Paul B.; Mcelroy, Paul M.; Hickey, Gregory S.

    1992-01-01

    Chemical treatment for creation of durable, low-surface-energy coatings for glass, ceramics and other protonated surfaces easily applied, and creates very thin semipermanent film with extremely low surface tension. Exhibits excellent stability; surfaces retreated if coating becomes damaged or eroded. Uses include water-repellent surfaces, oil-repellent surfaces, antimigration barriers, corrosion barriers, mold-release agents, and self-cleaning surfaces. Film resists wetting by water, alcohols, hydrocarbon solvents, and silicone oil. Has moderate resistance to abrasion, such as rubbing with cloths, and compression molding to polymers and composite materials.

  17. Numerical Simulations of Steady and Unsteady Transition in Low-Pressure Turbine Blade Rows

    NASA Technical Reports Server (NTRS)

    Dorney, Daniel

    1998-01-01

    Transition plays an important role in the prediction of losses and performance in low-pressure turbines. The transition location on a turbine blade may vary significantly because of the wakes from upstream blade rows, and intermittent flow separation can also affect the transition process in an unsteady flow environment. In the present investigation, an unsteady Navier-Stokes analysis is used to predict transition in a low-pressure turbine cascade and a low-pressure turbine stage. The numerical flow analysis is third-order spatially accurate and second-order temporally accurate, and the equations of motion are integrated using an implicit time-marching procedure. The Baldwin-Lomax and k-epsilon turbulence models, in conjunction with several algebraic transition models, have been used to predict the location of transition. Predicted results include unsteady blade loadings, time-histories of the pressure, transition locations and boundary layer quantities, as well as performance quantities and comparisons with the available experimental/design data.

  18. Toward the renewables - A natural gas/solar energy transition strategy

    NASA Technical Reports Server (NTRS)

    Hanson, J. A.; Escher, W. J. D.

    1979-01-01

    The inevitability of an energy transition from today's non-renewable fossil base toward a renewable energy base is considered from the viewpoint of the need for a national transition strategy. Then, one such strategy is offered. Its technological building blocks are described in terms of both energy use and energy supply. The strategy itself is then sketched at four points in its implementation; (1) initiation, (2) early transition, (3) late transition, and (4) completion. The transition is assumed to evolve from a heavily natural gas-dependent energy economy. It then proceeds through its transition toward a balanced, hybrid energy system consisting of both centralized and dispersed energy supply technologies supplying hydrogen and electricity from solar energy. Related institutional, environmental and economic factors are examined briefly.

  19. E-H mode transition in low-pressure inductively coupled nitrogen-argon and oxygen-argon plasmas

    SciTech Connect

    Lee, Young Wook; Lee, Hye Lan; Chung, T. H.

    2011-06-01

    This work investigates the characteristics of the E-H mode transition in low-pressure inductively coupled N{sub 2}-Ar and O{sub 2}-Ar discharges using rf-compensated Langmuir probe measurements and optical emission spectroscopy (OES). As the ICP power increases, the emission intensities from plasma species, the electron density, the electron temperature, and the plasma potential exhibit sudden changes. The Ar content in the gas mixture and total gas pressure have been varied in an attempt to fully characterize the plasma parameters. With these control parameters varying, the changes of the transition threshold power and the electron energy distribution function (EEDF) are explored. In N{sub 2}-Ar and O{sub 2}-Ar discharges at low-pressures of several millitorr, the transition thresholds are observed to decrease with Ar content and pressure. It is observed that in N{sub 2}-Ar plasmas during the transition, the shape of the EEDF changes from an unusual distribution with a flat hole near the electron energy of 3 eV in the E mode to a Maxwellian distribution in the H mode. However, in O{sub 2} -Ar plasmas, the EEDFs in the E mode at low Ar contents show roughly bi-Maxwellian distributions, while the EEDFs in the H mode are observed to be nearly Maxwellian. In the E and H modes of O{sub 2}-Ar discharges, the dissociation fraction of O{sub 2} molecules is estimated using optical emission actinometry. During the E-H mode transition, the dissociation fraction of molecules is also enhanced.

  20. Entanglement creation in low-energy scattering

    SciTech Connect

    Weder, Ricardo

    2011-12-15

    We study the entanglement creation in the low-energy scattering of two particles in three dimensions, for a general class of interaction potentials that are not required to be spherically symmetric. The incoming asymptotic state, before the collision, is a product of two normalized Gaussian states. After the scattering, the particles are entangled. We take as a measure of the entanglement the purity of one of them. We provide a rigorous explicit computation, with error bound, of the leading order of the purity at low energy. The entanglement depends strongly on the difference of the masses. It takes its minimum when the masses are equal, and it increases rapidly with the difference of the masses. It is quite remarkable that the anisotropy of the potential gives no contribution to the leading order of the purity, in spite of the fact that entanglement is a second-order effect.

  1. Low energy ion loss at Mars

    NASA Astrophysics Data System (ADS)

    Curry, S.; Liemohn, M.; Fang, X.; Ma, Y.

    2012-04-01

    Current data observations and modeling efforts have indicated that the low-energy pick-up ions on Mars significantly contribute to the overall escape rate. Due to the lack of a dipole magnetic field, the solar wind directly interacts with the dayside upper atmosphere causing particles to be stripped away. In this study, we use a 3-D Monte Carlo test particle simulation with virtual detectors to observe low energy ions (< 50 eV) in the Mars space environment. We will present velocity space distributions that can capture the asymmetric and non-gyrotropic features of particle motion. The effect of different solar conditions will also be discussed with respect to ion fluxes at various spatial locations as well as overall loss in order to robustly describe the physical processes controlling the distribution of planetary ions and atmospheric escape.

  2. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1985-01-01

    The author built and tested a low energy cyclotron for radiocarbon dating similar to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. The author found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. The author shows how a conventional carbon negative ion source located outside the cyclotron magnet, would produce sufficient beam and provide for quick sample changing to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  3. Durable low surface-energy surfaces

    NASA Technical Reports Server (NTRS)

    Willis, Paul B. (Inventor); McElroy, Paul M. (Inventor); Hickey, Gregory H. (Inventor)

    1993-01-01

    A formulation for forming a low surface-energy surface on a substrate having (i) a fluoroalkyl silane having a low surface energy part, (ii) a liquid crystal silane operable for enhancing the orientation of the molecules of the fluoroalkyl silane and for crosslinking with the fluoroalkyl silane, and, (iii) a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate. In one embodiment the formulation can includes a crosslinking agent for crosslinking the fluoroalkyl silane. In another embodiment the formulation has a condensation catalyst for enhancing chemical bonding of the fluoroalkyl silane to the substrate. The transport medium can be an alcohol such as methanol or ethanol.

  4. Low Energy Transfer to the Moon

    NASA Astrophysics Data System (ADS)

    Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

    In 1991, the Japanese Hiten mission used a low energy transfer with a ballistic capture at the Moon which required less Δ V than a standard Hohmann transfer. In this paper, we apply the dynamical systems techniques developed in our earlier work to reproduce systematically a Hiten-like mission. We approximate the Sun-Earth-Moon-spacecraft 4-body system as two 3-body systems. Using the invariant manifold structures of the Lagrange points of the 3-body systems, we are able to construct low energy transfer trajectories from the Earth which execute ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations.

  5. Landau-Zener transitions mediated by an environment: Population transfer and energy dissipation

    SciTech Connect

    Dodin, Amro; Simine, Lena; Segal, Dvira; Garmon, Savannah

    2014-03-28

    We study Landau-Zener transitions between two states with the addition of a shared discretized continuum. The continuum allows for population decay from the initial state as well as indirect transitions between the two states. The probability of nonadiabatic transition in this multichannel model preserves the standard Landau-Zener functional form except for a shift in the usual exponential factor, reflecting population transfer into the continuum. We provide an intuitive explanation for this behavior assuming individual, independent transitions between pairs of states. In contrast, the ground state survival probability at long time shows a novel, non-monotonic, functional form with an oscillatory behavior in the sweep rate at low sweep rate values. We contrast the behavior of this open-multistate model to other generalized Landau-Zener models incorporating an environment: the stochastic Landau-Zener model and the dissipative case, where energy dissipation and thermal excitations affect the adiabatic region. Finally, we present evidence that the continuum of states may act to shield the two-state Landau-Zener transition probability from the effect of noise.

  6. Model energy landscapes of low-temperature fluids: Dipolar hard spheres.

    PubMed

    Matyushov, Dmitry V

    2007-07-01

    An analytical model of non-Gaussian energy landscape of low-temperature fluids is developed based on the thermodynamics of the fluid of dipolar hard spheres. The entire excitation profile of the liquid, from the high-temperature liquid to the point of ideal-glass transition, has been obtained from Monte Carlo simulations. The fluid of dipolar hard spheres loses stability close to the point of ideal-glass transition transforming via a first-order transition into a columnar liquid phase of dipolar chains locally arranged in a body-centered-tetragonal order. Significant non-Gaussianity of the energy landscape is responsible for narrowing of the distribution of potential energies and energies of inherent structures with decreasing temperature. We suggest that the proposed functionality of the enumeration function is widely applicable to both polar and nonpolar low-temperature liquids.

  7. Seesaw scale from low-energy parameters

    SciTech Connect

    He Xiaogang

    2012-07-27

    Seesaw models can provide explanations why neutrino are so much lighter than their charged partners. However, A priori, the seesaw scale is not determined. In this talk, I report work published in Ref.[1] by Law, Volkas and myself which shows that it is possible to construct theoretical models where the seesaw scale is completely determined in terms of low-energy fermion mass, mixing angles and CP-violating phases observable quantities.

  8. Targeting Low-Energy Ballistic Lunar Transfers

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2010-01-01

    Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

  9. Low-energy electron interactions with biomolecules

    NASA Astrophysics Data System (ADS)

    Winstead, Carl

    2012-06-01

    Low-energy electron interactions with biomolecules have been the focus of sustained attention over the past decade. The demonstration by Sanche and coworkers that even subexcitation and subionization electrons can induce strand breaks in DNA opened a new frontier in understanding radiation damage to living systems. Many studies of DNA subunits and their analogues, both experimental and theoretical, have elucidated likely mechanisms by which slow electrons attach to and disrupt DNA, although the full picture is far from clear and some elements of it remain controversial. Increasing attention is also being given to low-energy electron collisions with amino acids in order to explore possible mechanisms of electron-mediated radiation damage to proteins. In a completely different context, electron-biomolecule collisions are fundamental to spark ignition and cumbustion of biofuels such as methanol and ethanol. Not to be overlooked, either, is the simplest but most ubiquitous biomolecule of all, water, whose low-energy electron cross sections remain surprisingly ill-characterized. This talk will survery recent ab initio computational studies using the Schwinger multichannel method of DNA- and protein-related molecules, alcohols, and water. Much of the work to be presented was carried out in collaboration with experimentalists who undertook complementary measurements, allowing for useful comparisons to be made. Although the primary focus will be on electronically elastic collisions relevant to dissociative attachment and electron transport, electron-impact excitation cross sections for water will be presented and discussed.

  10. Transitions.

    ERIC Educational Resources Information Center

    Field, David; And Others

    1992-01-01

    Includes four articles: "Career Aspirations" (Field); "Making the Transition to a New Curriculum" (Baker, Householder); "How about a 'Work to School' Transition?" (Glasberg); and "Technological Improvisation: Bringing CNC to Woodworking" (Charles, McDuffie). (SK)

  11. Low-Income African American Youth. Vulnerable Youth and the Transition to Adulthood

    ERIC Educational Resources Information Center

    Kuehn, Daniel; McDaniel, Marla

    2009-01-01

    The transition to adulthood could present challenges for African American youth from low-income families. This fact sheet uses data from the National Longitudinal Survey of Youth 1997 to explore racial differences in adolescent risk behavior, education, employment, and earnings among low income youth age 18 to 24. Differences discussed herein are…

  12. Borrowing and Working of Low-Income Students: The Impact of a Summer Transition Program

    ERIC Educational Resources Information Center

    De La Rosa, Mari Luna

    2012-01-01

    This study focuses on how low-income students determine employment and student loan borrowing options before they begin college, as part of the final stages of their college choice process. More specifically, this study asks, "during a six-week summer transition program, what choices are made by low-income students with employment or borrowing…

  13. Low-energy irradiation effects in cellulose

    SciTech Connect

    Polvi, Jussi; Nordlund, Kai

    2014-01-14

    Using molecular dynamics simulations, we determined the threshold energy for creating defects as a function of the incident angle for all carbon and oxygen atoms in the cellulose monomer. Our analysis shows that the damage threshold energy is strongly dependent on the initial recoil direction and on average slightly higher for oxygen atoms than for carbon atoms in cellulose chain. We also performed cumulative bombardment simulations mimicking low-energy electron irradiation (such as TEM imaging) on cellulose. Analyzing the results, we found that formation of free molecules and broken glucose rings were the most common forms of damage, whereas cross-linking and chain scission were less common. Pre-existing damage was found to increase the probability of cross-linking.

  14. Low to high energy beamstops for APT

    SciTech Connect

    Doll, D.; Hagan, T. van; Redler, K.; Tooker, J.; Baxter, A.; Schneider, D.; Spinos, F.; Fikani, M.; Funk, W.

    1998-12-31

    Beamstops are required for commissioning and operation of accelerators. The family of beamstops currently being developed for the DOE-sponsored Accelerator Production of Tritium (APT) program is addressed. The operational range encompasses proton energies of 6.7 MeV at the beginning of the RFQ to 1.7 GeV at the target/blanket, and both pulsed and cw operating modes. An additional beamstop was needed on a companion test facility to validate ion injector performance. This first of the series of beamstops has been built and operated; the second is under construction and will be operational by mid-1998. Particle stopping distance and duty factor drive the size and heat transfer capacity of these beamstops; the need for low neutron production and activation potential drives the material selection. At energies above 6.7 MeV, the preferred beamstop material is graphite with aluminum the choice for structures and helium the choice for coolant. Boronated water is the preferred shielding below 70 MeV, but is less suitable at higher energies because of the creation of Be-7. The evolution of the low-energy demonstration accelerator (LEDA) to 20 MeV and remaining APT beamstops are presented with performance ramifications and the status of the hardware and testing.

  15. Low energy neutrinos in Super-Kamiokande

    NASA Astrophysics Data System (ADS)

    Sekiya, Hiroyuki

    2016-05-01

    Super-Kamiokande (SK), a 50 kton water Cherenkov detector, observes 8B solar neutrinos via neutrino-electron elastic scattering. The analysis threshold was successfully lowered to 3.5 MeV (recoil electron kinetic energy) in SK-IV. To date SK has observed solar neutrinos for 18 years. An analysis regarding possible correlations between the solar neutrino flux and the 11 year solar activity cycle is shown. With large statistics, SK searches for distortions of the solar neutrino energy spectrum caused by the MSW resonance in the core of the sun. SK also searches for a day/night solar neutrino flux asymmetry induced by the matter in the Earth. The Super-Kamiokande Gd (SK-Gd) project is the upgrade of the SK detector via the addition of water-soluble gadolinium (Gd) salt. This modification will enable it to efficiently identify low energy anti-neutrinos. SK-Gd will pursue low energy physics currently inaccessible to SK due to backgrounds. The most important will be the world’s first observation of the diffuse supernova neutrino background. The main R&D program towards SK-Gd is EG ADS: a 200 ton, fully instrumented tank built in a new cavern in the Kamioka mine.

  16. Methods Of Sensitometry For Low Energy Radiography

    NASA Astrophysics Data System (ADS)

    Bednarek, Daniel R.; Rudin, Stephen; Wong, Roland

    1982-02-01

    Inverse-square sensitometry for low kVp techniques is limited by air attenuation and beam hardening. It is thus difficult to obtain accurate H and D curves for mammographic screen-film combinations at technique factors used clinically. Methods are described for the determination of characteristic curves at low x-ray energies which provide composite intensity-scale curves using small changes in source-to-receptor distance and concomitant changes in either exposure time, beam attenuation, or kVp. H and D curves obtained at low kVp's using the various sensitometric approaches are compared with those obtained using inverse-square sensitometry; the relative merits of the different methods are discussed.

  17. Boundary Layer Transition on Slender Cones in Conventional and Low Disturbance Mach 6 Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Horvath, Thomas J.; Berry, Scott A.; Hollis, Brian R.; Chang, Chau-Lyan; Singer, Bart A.

    2002-01-01

    An experimental investigation was conducted on a 5-degree half-angle cone and a 5-degree half-angle flared cone in a conventional Mach 6 wind tunnel to examine the effects of facility noise on boundary layer transition. The influence of tunnel noise was inferred by comparing transition onset locations determined from the present test to that previously obtained in a Mach 6 low disturbance quiet tunnel. Together, the two sets of experiments are believed to represent the first direct comparison of transition onset between a conventional and a low disturbance wind tunnel using a common test model and transition detection technique. In the present conventional hypersonic tunnel experiment, separate measurements of heat transfer and adiabatic wall temperatures were obtained on the conical models at small angles of attack over a range of Reynolds numbers, which resulted in laminar, transitional, and turbulent flow. Smooth model turbulent heating distributions are compared to that obtained with transition forced via discrete surface roughness. The model nosetip radius was varied to examine the effects of bluntness on transition onset. Despite wall to total temperature differences between the transient heating measurements and the adiabatic wall temperature measurement, the two methods for determining sharp cone transition onset generally yielded equivalent locations. In the 'noisy' mode of the hypersonic low disturbance tunnel, transition onset occurred earlier than that measured in the conventional hypersonic tunnel, suggesting higher levels of freestream acoustic radiation relative to the conventional tunnel. At comparable freestream conditions, the transition onset Reynolds number under low disturbance conditions was a factor of 1.3 greater than that measured on flared cone in the LaRC conventional hypersonic tunnel and a factor of 1.6 greater that the flared cone run in the low disturbance tunnel run 'noisy'. Navier-Stokes mean flow computations and linear stability

  18. Hydrogen and Fuel Cell Transit Bus Evaluations: Joint Evaluation Plan for the U.S. Department of Energy and the Federal Transit Administration (Report and Appendix)

    SciTech Connect

    Eudy, L.; Chandler, K.

    2008-05-01

    This document describes the hydrogen transit bus evaluations performed by the National Renewable Energy Laboratory (NREL) and funded by the U.S. Department of Energy (DOE) and the U.S. Department of Transportation's Federal Transit Administration (FTA).

  19. Simulating boundary layer transition with low-Reynolds-number k-epsilon turbulence models. I - An evaluation of prediction characteristics. II - An approach to improving the predictions

    NASA Technical Reports Server (NTRS)

    Schmidt, R. C.; Patankar, S. V.

    1991-01-01

    The capability of two k-epsilon low-Reynolds number (LRN) turbulence models, those of Jones and Launder (1972) and Lam and Bremhorst (1981), to predict transition in external boundary-layer flows subject to free-stream turbulence is analyzed. Both models correctly predict the basic qualitative aspects of boundary-layer transition with free stream turbulence, but for calculations started at low values of certain defined Reynolds numbers, the transition is generally predicted at unrealistically early locations. Also, the methods predict transition lengths significantly shorter than those found experimentally. An approach to overcoming these deficiencies without abandoning the basic LRN k-epsilon framework is developed. This approach limits the production term in the turbulent kinetic energy equation and is based on a simple stability criterion. It is correlated to the free-stream turbulence value. The modification is shown to improve the qualitative and quantitative characteristics of the transition predictions.

  20. Local energy governance in vermont: an analysis of energy system transition strategies and actor capacity

    NASA Astrophysics Data System (ADS)

    Rowse, Tarah

    While global, national, and regional efforts to address climate and energy challenges remain essential, local governments and community groups are playing an increasingly stronger and vital role. As an active state in energy system policy, planning and innovation, Vermont offers a testing ground for research into energy governance at the local level. A baseline understanding of the energy planning and energy organizing activities initiated at the local level can support efforts to foster a transition to a sustainable energy system in Vermont. Following an inductive, applied and participatory approach, and grounded in the fields of sustainability transitions, energy planning, and community energy, this research project identifies conditions for change, including opportunities and challenges, within Vermont energy system decision-making and governance at the local level. The following questions are posed: What are the main opportunities and challenges for sustainable energy development at the town level? How are towns approaching energy planning? What are the triggers that will facilitate a faster transition to alternative energy systems, energy efficiency initiatives, and localized approaches? In an effort to answer these questions two studies were conducted: 1) an analysis of municipal energy plans, and 2) a survey of local energy actors. Study 1 examined Vermont energy planning at the state and local level through a review and comparison of 40 municipal plan energy chapters with the state 2011 Comprehensive Energy Plan. On average, municipal plans mentioned just over half of the 24 high-level strategies identified in the Comprehensive Energy Plan. Areas of strong and weak agreement were examined. Increased state and regional interaction with municipal energy planners would support more holistic and coordinated energy planning. The study concludes that while municipalities are keenly aware of the importance of education and partnerships, stronger policy mechanisms

  1. Transition through co-optation: Harnessing carbon democracy for clean energy

    NASA Astrophysics Data System (ADS)

    Meng, Kathryn-Louise

    This dissertation explores barriers to a clean energy transition in the United States. Clean energy is demonstrably viable, yet the pace of clean energy adoption in the U.S. is slow, particularly given the immediate threat of global climate change. The purpose of this dissertation is to examine the factors inhibiting a domestic energy transition and to propose pragmatic approaches to catalyzing a transition. The first article examines the current political-economic and socio-technical energy landscape in the U.S. Fossil fuels are central to the functioning of the American economy. Given this centrality, constellations of power have been constructed around the reliable and affordable access of fossil fuels. The fossil fuel energy regime is comprised of: political-economic networks with vested interests in continued fossil fuel reliance, and fixed infrastructure that is minimally compatible with distributed generation. A transition to clean energy threatens the profitability of fossil fuel regime actors. Harnessing structural critiques from political ecology and process and function-oriented socio-technical systems frameworks, I present a multi-level approach to identifying pragmatic means to catalyzing an energy transition. High-level solutions confront the existing structure, mid-level solutions harness synergy with the existing structure, and low-level solutions lie outside of the energy system or foster the TIS. This is exemplified using a case study of solar development in Massachusetts. Article two presents a case study of the clean energy technological innovation system (TIS) in Massachusetts. I examine the actors and institutions that support cleantech development. Further, I scrutinize the actors and institutions that help sustain the TIS support system. The concept of a catalyst is presented; a catalyst is an actor that serves to propel TIS functions. Catalysts are critical to facilitating anchoring. Strategic corporate partners are identified as powerful

  2. Test of tokamak low-mode--high-mode transition theory in stellarators

    SciTech Connect

    Shaing, K.C. )

    1993-11-01

    The tokamak L--H (low-mode--high mode) transition theory can be tested in stellarators in a controlled manner by making use of the two or more local maxima in poloidal viscosity in these devices. Depending on the relative magnitudes of the toroidal and helical components of the magnetic-field spectrum, the local maxima, and thus transition, can occur either at a critical poloidal [bold E][times][bold B] Mach number [ital M][sub [ital p

  3. Low-energy electron-atom bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Gould, R. J.

    1986-01-01

    This paper extends recent work providing an elementary calculation of bremsstrahlung and opacity associated with the scattering of low-energy electrons by neutral atoms and molecules. The method applies when the scattering potential is 'hard' or when the collision time is short, applying the classical soft-photon emission probability formula for arbitrary bremsstrahlung photon energy. However, now, in addition to correcting the probability factor for finite bremsstrahlung photon energy, another factor corrects for the reduced phase space available to the outgoing electron. The bremsstrahlung cross section and opacity are then computed directly from the elastic scattering cross section, determined experimentally or calculated; a small (approximately 10 percent) correction is computed from the anisotropic term in the elastic scattering cross section. The opacity is evaluated for electron scattering by H, He, and H2 using experimentally determined values for the elastic scattering cross section, and is compared with more elaborate calculations. The agreement is good (within 10 percent), indicating an accuracy for the general method comparable to variations among the results of different elaborate theoretical computations. The agreement seems to validate the basic approximation of short collision time even at large bremsstrahlung photon energy for electron energies and temperatures up to a few eV.

  4. Surface self-diffusion constants at low temperature: Monte Carlo transition state theory with importance sampling

    SciTech Connect

    Voter, A.F.; Doll, J.D.

    1984-06-01

    We present an importance-sampling method which, when combined with a Monte Carlo procedure for evaluating transition state theory rates, allows computation of classically exact, transition state theory surface diffusion constants at arbitrarily low temperature. In the importance-sampling method, a weighting factor is applied to the transition state region, and Metropolis steps are chosen from a special distribution which facilitates transfer between the two important regions of configuration space: the binding site minimum and the saddle point between two binding sites. We apply the method to the diffusion of Rh on Rh(111) and Rh on Rh(100), in the temperature range of existing field ion microscope experiments.

  5. Transitions to spatiotemporal chaos and turbulence of flute instabilities in a low-{beta} magnetized plasma

    SciTech Connect

    Brochard, F.; Gravier, E.; Bonhomme, G.

    2006-03-15

    The spatiotemporal transition scenario of flute instabilities from a regular to a turbulent state is experimentally investigated in the low-{beta} plasma column of a thermionic discharge. The same transition scenario, i.e., the Ruelle-Takens route to turbulence, is found for both the Kelvin-Helmholtz and the Rayleigh-Taylor instabilities. It is demonstrated that the transition can be more or less smooth, according to the discharge mode. In both cases, a strong radial dependence is observed, which is linked to the velocity shear layer in the case of the Kelvin-Helmholtz instability.

  6. Low energy demonstration accelerator technical area 53

    SciTech Connect

    1996-04-01

    As part of the Department of Energy`s (DOE) need to maintain the capability of producing tritium in support of its historic and near-term stewardship of the nation`s nuclear weapons stockpile, the agency has recently completed a Programmatic Environmental Impact Statement for Tritium Supply and Recycling. The resulting Record of Decision (ROD) determined that over the next three years the DOE would follow a dual-track acquisition strategy that assures tritium production for the nuclear weapon stockpile in a rapid, cost effective, and safe manner. Under this strategy the DOE will further investigate and compare two options for producing tritium: (1) purchase of an existing commercial light-water reactor or irradiation services with an option to purchase the reactor for conversion to a defense facility; and (2) design, build, and test critical components of a system for accelerator production of tritium (APT). The final decision to select the primary production option will be made by the Secretary of Energy in the October 1998 time frame. The alternative not chosen as the primary production method, if feasible, would be developed as a back-up tritium supply source. This Environmental Assessment (EA) analyzes the potential environmental effects that would be expected to occur if the DOE were to design, build, and test critical prototypical components of the accelerator system for tritium production, specifically the front-end low-energy section of the accelerator, at Los Alamos National Laboratory. The Low Energy Demonstration Accelerator (LEDA) would be incrementally developed and tested in five separate stages over the next seven years. The following issues were evaluated for the proposed action: utility demands, air, human health, environmental restoration, waste management, transportation, water, threatened and endangered species, wetlands, cultural resources, and environmental justice.

  7. Transition Metal Oxide Alloys as Potential Solar Energy Conversion Materials

    SciTech Connect

    Toroker, Maytal; Carter, Emily A.

    2013-02-21

    First-row transition metal oxides (TMOs) are inexpensive potentia alternative materials for solar energy conversion devices. However, some TMOs, such as manganese(II) oxide, have band gaps that are too large for efficiently absorbing solar energy. Other TMOs, such as iron(II) oxide, have conduction and valence band edges with the same orbital character that may lead to unfavorably high electron–hole recombination rates. Another limitation of iron(II) oxide is that the calculated valence band edge is not positioned well for oxidizing water. We predict that key properties, including band gaps, band edge positions, and possibly electron–hole recombination rates, may be improved by alloying TMOs that have different band alignments. A new metric, the band gap center offset, is introduced for simple screening of potential parent materials. The concept is illustrated by calculating the electronic structure of binary oxide alloys that contain manganese, nickel, iron, zinc, and/or magnesium, within density functional theory (DFT)+U and hybrid DFT theories. We conclude that alloys of iron(II) oxide are worth evaluating further as solar energy conversion materials.

  8. Predictions of Separated and Transitional Boundary Layers Under Low-Pressure Turbine Airfoil Conditions Using an Intermittency Transport Equation

    NASA Technical Reports Server (NTRS)

    Suzen, Y. B.; Huang, P. G.; Hultgren, Lennart S.; Ashpis, David E.

    2003-01-01

    A new transport equation for the intermittency factor was proposed to predict separated and transitional boundary layers under low-pressure turbine airfoil conditions. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, t , with the intermittency factor, y. Turbulent quantities are predicted by using Menter s two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model, which not only can reproduce the experimentally observed streamwise variation of the intermittency in the transition zone, but also can provide a realistic cross-stream variation of the intermittency profile. In this paper, the intermittency model is used to predict a recent separated and transitional boundary layer experiment under low pressure turbine airfoil conditions. The experiment provides detailed measurements of velocity, turbulent kinetic energy and intermittency profiles for a number of Reynolds numbers and freestream turbulent intensity conditions and is suitable for validation purposes. Detailed comparisons of computational results with experimental data are presented and good agreements between the experiments and predictions are obtained.

  9. Household Energy Consumption: Community Context and the Fuelwood Transition*

    PubMed Central

    Link, Cynthia F.; Axinn, William G.; Ghimire, Dirgha J.

    2012-01-01

    We examine the influence of community context on change over time in households’ use of non-wood fuels. Our theoretical framework builds on sociological concepts in order to study energy consumption at the micro-level. The framework emphasizes the importance of nonfamily organizations and services in the local community as determinants of the transition from use of fuelwood to use of alternative fuels. We use multilevel longitudinal data on household fuel choice and community context from rural Nepal to provide empirical tests of our theoretical model. Results reveal that increased exposure to nonfamily organizations in the local community increases the use of alternative fuels. The findings illustrate key features of human impacts on the local environment and motivate greater incorporation of social organization into research on environmental change. PMID:23017795

  10. Noise-induced transitions in rugged energy landscapes

    NASA Astrophysics Data System (ADS)

    Duncan, A. B.; Kalliadasis, S.; Pavliotis, G. A.; Pradas, M.

    2016-09-01

    We consider the problem of an overdamped Brownian particle moving in multiscale potential with N +1 characteristic length scales: the macroscale and N separated microscales. We show that the coarse-grained dynamics is given by an overdamped Langevin equation with respect to the free energy and with a space-dependent diffusion tensor, the calculation of which requires the solution of N fully coupled Poisson equations. We study in detail the structure of the bifurcation diagram for one-dimensional problems, and we show that the multiscale structure in the potential leads to hysteresis effects and to noise-induced transitions. Furthermore, we obtain an explicit formula for the effective diffusion coefficient for a self-similar separable potential, and we investigate the limit of infinitely many small scales.

  11. Transition metal oxide hierarchical nanotubes for energy applications.

    PubMed

    Wei, Wei; Wang, Yongcheng; Wu, Hao; Al-Enizi, Abdullah M; Zhang, Lijuan; Zheng, Gengfeng

    2016-01-15

    We report a general synthetic method for transition metal oxide (TMO) hierarchical nanotube (HNT) structures by a solution-phase cation exchange method from Cu2O nanowire templates. This method leads to the formation of hollow, tubular backbones with secondary, thin nanostructures on the tube surface, which substantially increases the surface reactive sites for electrolyte contacts and electrochemical reactions. As proofs-of-concept, several representative first-row TMO HNTs have been synthesized, including CoOx, NiOx, MnOx, ZnOx and FeOx, with specific surface areas much larger than nanotubes or nanoparticles of corresponding materials. An example of the potential energy storage applications of CoOx HNTs as supercapacitors is also demonstrated. PMID:26629880

  12. Low Energy Lorentz Violation from Modified Dispersion at High Energies.

    PubMed

    Husain, Viqar; Louko, Jorma

    2016-02-12

    Many quantum theories of gravity propose Lorentz-violating dispersion relations of the form ω=|k|f(|k|/M⋆), with recovery of approximate Lorentz invariance at energy scales much below M⋆. We show that a quantum field with this dispersion predicts drastic low energy Lorentz violation in atoms modeled as Unruh-DeWitt detectors, for any f that dips below unity somewhere. As an example, we show that polymer quantization motivated by loop quantum gravity predicts such Lorentz violation below current ion collider rapidities.

  13. Fission dynamics at low excitation energy

    NASA Astrophysics Data System (ADS)

    Aritomo, Y.; Chiba, S.; Ivanyuk, F.

    2014-11-01

    The mass asymmetry in the fission of 236U at low excitation energy is clarified by the analysis of the trajectories obtained by solving the Langevin equations for the shape degrees of freedom. It is demonstrated that the position of the peaks in the mass distribution of fission fragments is determined mainly by the saddle point configuration originating from the shell correction energy. The width of the peaks, on the other hand, results from the shape fluctuations close to the scission point caused by the random force in the Langevin equation. We have found out that the fluctuations between elongated and compact shapes are essential for the fission process. According to our results the fission does not occur with continuous stretching in the prolate direction, similarly to that observed in starch syrup, but is accompanied by the fluctuations between elongated and compact shapes. This picture presents a new viewpoint of fission dynamics and the splitting mechanism.

  14. Detection of low energy antimatter with emulsions

    NASA Astrophysics Data System (ADS)

    Aghion, S.; Ariga, A.; Ariga, T.; Bollani, M.; Dei Cas, E.; Ereditato, A.; Evans, C.; Ferragut, R.; Giammarchi, M.; Pistillo, C.; Romé, M.; Sala, S.; Scampoli, P.

    2016-06-01

    Emulsion detectors feature a very high position resolution and consequently represent an ideal device when particle detection is required at the micrometric scale. This is the case of quantum interferometry studies with antimatter, where micrometric fringes have to be measured. In this framework, we designed and realized a new emulsion based detector characterized by a gel enriched in terms of silver bromide crystal contents poured on a glass plate. We tested the sensitivity of such a detector to low energy positrons in the range 10–20 keV . The obtained results prove that nuclear emulsions are highly efficient at detecting positrons at these energies. This achievement paves the way to perform matter-wave interferometry with positrons using this technology.

  15. Oscillations of very low energy atmospheric neutrinos

    SciTech Connect

    Peres, Orlando L. G.; Smirnov, A. Yu.

    2009-06-01

    There are several new features in the production, oscillations, and detection of the atmospheric neutrinos of low energies E < or approx. 100 MeV. The flavor ratio r of muon to electron neutrino fluxes is substantially smaller than 2 and decreases with energy, a significant part of events is due to the decay of invisible muons at rest, etc. Oscillations in a two-layer medium (atmosphere-Earth) should be taken into account. We derive analytical and semianalytical expressions for the oscillation probabilities of these 'sub-sub-GeV' neutrinos. The energy spectra of the e-like events in water Cherenkov detectors are computed, and the dependence of the spectra on the 2-3 mixing angle {theta}{sub 23}, the 1-3 mixing, and the CP-violation phase are studied. We find that variations of {theta}{sub 23} in the presently allowed region change the number of e-like events by about 15%-20% as well as lead to distortion of the energy spectrum. The 1-3 mixing and CP violation can lead to {approx}10% effects. Detailed study of the sub-sub-GeV neutrinos will be possible in future megaton-scale detectors.

  16. Low-energy proton capture reactions

    SciTech Connect

    Lipoglavsek, M.; Cvetinovic, A.; Gajevic, J.; Likar, A.; Vavpetic, P.; Petrovic, T.

    2014-05-09

    An overview of experimental problems in measuring the cross sections for (p,γ) and (p,n) reactions at low energies is given with a specific emphasis on electron screening in metallic targets. Thick target γ-ray and neutron yields are compared for Ni and NiO targets, V and VO{sub 2} targets and Mn and MnO targets. The {sup 1}H({sup 7}Li,α){sup 4}He reaction was studied in inverse kinematics with hydrogen loaded into Pd and PdAg alloy foils from gas phase. Based on these results, a new approach to electron screening in nuclear reactions is suggested.

  17. Low energy fission: dynamics and scission configurations

    NASA Astrophysics Data System (ADS)

    Goutte, H.; Berger, J.-F.; Gogny, D.; Younes, W.

    2005-11-01

    In the first part of this paper we recall a recent study concerning low energy fission dynamics. Propagation is made by use of the Time Dependent Generator Coordinate Method, where the basis states are taken from self-consistent Hartree-Fock-Bogoliubov calculations with the Gogny force. Theoretical fragment mass distributions are presented and compared with the evaluation made by Wahl. In the second part of this paper, new results concerning scission configurations are shown. Deviations of the fission fragment proton numbers from the Unchanged Charge Distribution prescription and fission fragment deformations are discussed.

  18. The low energy booster project status

    SciTech Connect

    Tuttle, G.W.

    1993-05-01

    In order to achieve the required injection momentum, the Superconducting Super Collider (SSC) has an accelerator chain comprised of a Linear Accelerator and three synchrotrons. The Low Energy Booster (LEB) is the first synchrotron in this chain. The LEB project has made significant progress in the development of major subsystems and conventional construction. This paper briefly reviews the performance requirements of the LEB and describes significant achievements in each of the major subsystem areas. Highlighted among these achievements are the LEB foreign collaborations with the Budker Institute of Nuclear Physics (BINP) located in Novosibirsk, Russia.

  19. Low energy beam transport system developments

    NASA Astrophysics Data System (ADS)

    Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.

    2015-04-01

    For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H- beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H- beams, but such gas densities cause unacceptably high H- beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H- beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.

  20. The Gardner Transition: A new approach for understanding low-temperature glasses

    NASA Astrophysics Data System (ADS)

    Charbonneau, Patrick

    Recent theoretical advances in the mean-field theory of glasses predict the existence deep in the glass phase of a novel phase transition, a so-called Gardner transition. This transition signals the emergence of a complex free energy landscape composed of a marginally stable hierarchy of sub-basins within a broad glass metabasin. It is thus the onset of marked changes in thermal and transport properties of glasses, and ultimately leads to the unusual critical behavior at jamming. The Gardner transition itself is immediately related to a diverging (i) characteristic relaxation time, (ii) caging susceptibility and (iii) correlation length of the caging heterogeneity as well as aging, even in well-thermalized glasses. We have detected some of these signatures both in a mean-field model and in standard hard-sphere glass formers. We find the results to quantitatively agree with theory in the former and qualitatively so in the latter, which suggest that the transition should be detectable in a wide array of numerical and experimental systems. Interestingly, although the Gardner transitions is primarily associated with structural glass formers, we also find features of the transition in crystals of polydisperse particles once the landscape becomes rough.

  1. Methods for finding transition states on reduced potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Burger, Steven K.; Ayers, Paul W.

    2010-06-01

    Three new algorithms are presented for determining transition state (TS) structures on the reduced potential energy surface, that is, for problems in which a few important degrees of freedom can be isolated. All three methods use constrained optimization to rapidly find the TS without an initial Hessian evaluation. The algorithms highlight how efficiently the TS can be located on a reduced surface, where the rest of the degrees of freedom are minimized. The first method uses a nonpositive definite quasi-Newton update for the reduced degrees of freedom. The second uses Shepard interpolation to fit the Hessian and starts from a set of points that bound the TS. The third directly uses a finite difference scheme to calculate the reduced degrees of freedom of the Hessian of the entire system, and searches for the TS on the full potential energy surface. All three methods are tested on an epoxide hydrolase cluster, and the ring formations of cyclohexane and cyclobutenone. The results indicate that all the methods are able to converge quite rapidly to the correct TS, but that the finite difference approach is the most efficient.

  2. Energy boost in laser wakefield accelerators using sharp density transitions

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Lifschitz, A.; Ta Phuoc, K.; Malka, V.

    2016-05-01

    The energy gain in laser wakefield accelerators is limited by dephasing between the driving laser pulse and the highly relativistic electrons in its wake. Since this phase depends on both the driver and the cavity length, the effects of dephasing can be mitigated with appropriate tailoring of the plasma density along propagation. Preceding studies have discussed the prospects of continuous phase-locking in the linear wakefield regime. However, most experiments are performed in the highly non-linear regime and rely on self-guiding of the laser pulse. Due to the complexity of the driver evolution in this regime, it is much more difficult to achieve phase locking. As an alternative, we study the scenario of rapid rephasing in sharp density transitions, as was recently demonstrated experimentally. Starting from a phenomenological model, we deduce expressions for the electron energy gain in such density profiles. The results are in accordance with particle-in-cell simulations, and we present gain estimations for single and multiple stages of rephasing.

  3. Photoinduced energy transfer in transition metal complex oligomers

    SciTech Connect

    1997-06-01

    The work done over the past three years has been directed toward the preparation, characterization and photophysical examination of mono- and bimetallic diimine complexes. The work is part of a broader project directed toward the development of stable, efficient, light harvesting arrays of transition metal complex chromophores. One focus has been the synthesis of rigid bis-bidentate and bis-tridentate bridging ligands. The authors have managed to make the ligand bphb in multigram quantities from inexpensive starting materials. The synthetic approach used has allowed them to prepare a variety of other ligands which may have unique applications (vide infra). They have prepared, characterized and examined the photophysical behavior of Ru(II) and Re(I) complexes of the ligands. Energy donor/acceptor complexes of bphb have been prepared which exhibit nearly activationless energy transfer. Complexes of Ru(II) and Re(I) have also been prepared with other polyunsaturated ligands in which two different long lived (> 50 ns) excited states exist; results of luminescence and transient absorbance measurements suggest the two states are metal-to-ligand charge transfer and ligand localized {pi}{r_arrow}{pi}* triplets. Finally, the authors have developed methods to prepare polymetallic complexes which are covalently bound to various surfaces. The long term objective of this work is to make light harvesting arrays for the sensitization of large band gap semiconductors. Details of this work are provided in the body of the report.

  4. Photoinduced energy transfer in transition metal complex oligomers

    SciTech Connect

    1997-04-01

    The work we have done over the past three years has been directed toward the preparation, characterization and photophysical examination of mono- and bimetallic diimine complexes. The work is part of a broader project directed toward the development of stable, efficient, light harvesting arrays of transition metal complex chromophores. One focus has been the synthesis of rigid bis-bidentate and bis-tridentate bridging ligands. We have managed to make the ligand bphb in multigram quantities from inexpensive starting materials. The synthetic approach used has allowed us prepare a variety of other ligands which may have unique applications (vide infra). We have prepared, characterized and examined the photophysical behavior of Ru(II) and Re(I) complexes of the ligands. Energy donor/acceptor complexes of bphb have been prepared which exhibit nearly activationless energy transfer. Complexes of Ru(II) and Re(I) have also been prepared with other polyunsaturated ligands in which two different long lived ( > 50 ns) excited states exist; results of luminescence and transient absorbance measurements suggest the two states are metal-to-ligand charge transfer and ligand localized {pi}{r_arrow}{pi}* triplets. Finally, we have developed methods to prepare polymetallic complexes which are covalently bound to various surfaces. The long term objective of this work is to make light harvesting arrays for the sensitization of large band gap semiconductors. Details of this work are provided in the body of the report.

  5. Low-energy electron scattering from cyanamide

    NASA Astrophysics Data System (ADS)

    Wang, Kedong; Guo, Shuangcheng; Meng, Ju; Huang, Xiaotian; Wang, Yongfeng

    2016-09-01

    The low-energy electron collisions with cyanamide molecule are investigated by using the UK molecular R -matrix codes for electron energies ranging from 0.01 eV to 10 eV. Three models including static-exchange, static-exchange plus polarization, and close-coupling (CC) approximations are employed to reveal the dynamic interaction. Elastic (integrated and differential), momentum-transfer, and excitation cross sections from the ground state to the three low-lying electron excited states have been presented. Two shape resonances, two core-excited resonances, and two Feshbach resonances are detected in the CC approximation. The role of active space in the target and scattering problem including the resonances is discussed. The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. These resonances may be responsible for the fragments observed in a recent experiment of the dissociative electron attachments to cyanamide. Since the cyanamide molecule has a large permanent dipole moment, a Born closure procedure is used to account for the contribution of partial waves higher than l =4 to obtain converged cross sections.

  6. Low energy CMOS for space applications

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Alkalaj, Leon

    1992-01-01

    The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

  7. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1984-12-01

    The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. We show how a conventional carbon negative ion source, located outside the cyclotron magnet, would produce sufficient beam and provide for quick sampling to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  8. Primary transitions between the yrast superdeformed band and low-lying normal deformed states in {sup 194}Pb

    SciTech Connect

    Hauschild, K.; Bernstein, L.A.; Becker, J.A.

    1996-12-31

    The observation of one-step `primary` gamma-ray transitions directly linking the superdeformed (SD) states to the normal deformed (ND) low-lying states of known excitation energies (E{sub x}), spins and parities (J{sup {pi}}) is crucial to determining the E{sub x} and J{sup {pi}} of the SD states. With this knowledge one can begin to address some of the outstanding problems associated with SD nuclei, such as the identical band issue, and one can also place more stringent restrictions on theoretical calculations which predict SD states and their properties. Brinkman, et al., used the early implementation of the GAMMASPHERE spectrometer array (32 detectors) and proposed a single, candidate {gamma} ray linking the {sup 194}Pb yrast SD band to the low-lying ND states in {sup 194}Pb. Using 55 detectors in the GAMMASPHERE array Khoo, et al., observed multiple links between the yrast SD band in {sup 194}Hg and the low-lying level scheme and conclusively determined E{sub x} and J of the yrast SD states. Here the authors report on an experiment in which Gammasphere with 88 detectors was used and the E{sub x} and J{sup {pi}} values of the yrast SD states in {sup 194}Pb were uniquely determined. Twelve one-step linking transitions between the yrast SD band and low-lying states in {sup 194}Pb have been identified, including the transition proposed by Brinkman. These transitions have been placed in the level scheme of {sup 194}Pb using coincidence relationships and agreements between the energies of the primary transitions and the energy differences in level spacings. Furthermore, measurements of angular asymmetries have yielded the multipolarities of the primaries which have allowed J{sup {pi}} assignments of the {sup 194}Pb SD states to be unambiguously determined for the first time without a priori assumptions about the character of SD bands. A study performed in parallel to this work using the EUROGAM-II array reports similar, but somewhat less extensive, results.

  9. Calibration of the 7—Equation Transition Model for High Reynolds Flows at Low Mach

    NASA Astrophysics Data System (ADS)

    Colonia, S.; Leble, V.; Steijl, R.; Barakos, G.

    2016-09-01

    The numerical simulation of flows over large-scale wind turbine blades without considering the transition from laminar to fully turbulent flow may result in incorrect estimates of the blade loads and performance. Thanks to its relative simplicity and promising results, the Local-Correlation based Transition Modelling concept represents a valid way to include transitional effects into practical CFD simulations. However, the model involves coefficients that need tuning. In this paper, the γ—equation transition model is assessed and calibrated, for a wide range of Reynolds numbers at low Mach, as needed for wind turbine applications. An aerofoil is used to evaluate the original model and calibrate it; while a large scale wind turbine blade is employed to show that the calibrated model can lead to reliable solutions for complex three-dimensional flows. The calibrated model shows promising results for both two-dimensional and three-dimensional flows, even if cross-flow instabilities are neglected.

  10. Rail transit energy management program. Final report for 1993-94 calendar year effort. Volume 1

    SciTech Connect

    Uher, R.A.

    1995-03-01

    To meet the challenge of continuously rising energy costs for rail transit in North America, the Rail Systems Center (RSC) at Carnegie Mellon University has established the Rail Transit Energy Management Program. This program is a private-public partnership of rail transit authorities, the electric utilities which supply them energy and suppliers to both the transit and the electric utility industry. The long range goal of the program is to reduce rail transit energy costs by 10% or $46 million, annually. The program is built upon an already successful effort of energy cost reduction among several rail transit authorities and the RSC. This report describes the effort expended on the program during the calendar years 1993-94.

  11. Rail transit energy management program. Final report, calendar year 1995-1996. Final report

    SciTech Connect

    Uher, R.A.

    1996-04-01

    To meet the challenge of continuously rising energy costs for rail transit in North America, the Rail Systems Center (RSC) at Carnegie Mellon University has established the Rail transit Energy management Program. This program is a private-public partnership of rail transit authorities, the electric utilities which supply them energy and suppliers to both the transit and the electric utility industry. The long range goal of the program is to reduce rail transit energy costs by 10% or $46 million, annually. The program is built upon an already successful effort of energy cost reduction among several rail transit authorities and the RSC. The report describes the effort expended on the program during the clanedar years 1995-1996.

  12. Ionization efficiency study for low energy nuclear recoils in germanium

    NASA Astrophysics Data System (ADS)

    Barker, D.; Wei, W.-Z.; Mei, D.-M.; Zhang, C.

    2013-08-01

    We used the internal conversion (E0 transition) of germanium-72 to indirectly measure the low energy nuclear recoils of germanium. Together with a reliable Monte Carlo package, in which we implement the internal conversion process, the data was compared to the Lindhard (k = 0.159) and Barker-Mei models. A shape analysis indicates that both models agree well with data in the region of interest within 4%. The most probable value (MPV) of the nuclear recoils obtained from the shape analysis is 17.5 ± 0.12 (sys) ±0.035 (stat) keV with an average path-length of 0.014 μm.

  13. Low energy stable plasma calibration facility.

    PubMed

    Frederick-Frost, K M; Lynch, K A

    2007-07-01

    We have designed and fabricated a low energy plasma calibration facility for testing and calibration of rocket-borne charged-particle detectors and for the investigation of plasma sheath formation in an environment with ionospheric plasma energies, densities, and Debye lengths. We describe the vacuum system and associated plasma source, which was modified from a Naval Research Laboratory design [Bowles et al. Rev. Sci. Instrum. 67, 455 (1996)]. Mechanical and electrical modifications to this cylindrical microwave resonant source are outlined together with a different method of operating the magnetron that achieves a stable discharge. This facility produces unmagnetized plasmas with densities from 1x10(3)/cm(3) to 6x10(5)/cm(3), electron temperatures from 0.1 to 1.7 eV, and plasma potentials from 0.5 to 8 V depending on varying input microwave power and neutral gas flow. For the range of input microwave power explored (350-600 W), the energy density of the plasma remains constant because of an inverse relationship between density and temperature. This relationship allows a wide range of Debye lengths (0.3-8.4 cm) to be investigated, which is ideal for simulating the ionospheric plasma sheaths we explore.

  14. Low Energy Electron Scattering from Fuels

    NASA Astrophysics Data System (ADS)

    Lopes, M. C. A.; Silva, D. G. M.; Bettega, M. H. F.; da Costa, R. F.; Lima, M. A. P.; Khakoo, M. A.; Winstead, C.; McKoy, V.

    2012-11-01

    In order to understand and optimize processes occurring during the ignition of plasma and its consequences in post-discharge for an internal combustion engine, especially considering the spark plug, we have produced in this work some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules in the energy range from 60 to 500 eV are reported, using the linear transmission method based on the Beer-Lambert law to first approximation. Aditionally to that, measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering were also discussed, for impact energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°-130°. The measurements were obtained using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons.

  15. Highly correlated systems. Excitation energies of first row transition metals Sc-Cu

    NASA Astrophysics Data System (ADS)

    Raghavachari, Krishnan; Trucks, Gary W.

    1989-07-01

    The low-lying dns2→dn+1s1 excitation energies of the first row transition metal atoms Sc-Cu are calculated using fourth-order M≂ller-Plesset perturbation theory (MP4) as well as quadratic configuration interaction (QCI) techniques with large spd and spdf basis sets. The MP4 method performs well for Sc-Mn but fails dramatically for Fe-Cu. In contrast, the QCI technique performs uniformly for all excitation energies with a mean deviation from experiment of only 0.14 eV after including relativistic corrections. f functions contribute 0.1-0.4 eV to the excitation energies for these systems. The highly correlated d10 state of the Ni atom is also considered in detail. The QCI technique obtains the d9s1→d10 splitting of the Ni atom with an error of only 0.13 eV. The results show that single-configuration Hartree-Fock based methods can be successful in calculating excitation energies of transition metal atoms.

  16. Excitation energies, polarizabilities, multipole transition rates, and lifetimes of ions along the francium isoelectronic sequence

    SciTech Connect

    Safronova, U. I.; Johnson, W. R.; Safronova, M. S.

    2007-10-15

    Relativistic many-body perturbation theory is applied to study properties of ions of the francium isoelectronic sequence. Specifically, energies of the 7s, 7p, 6d, and 5f states of Fr-like ions with nuclear charges Z=87-100 are calculated through third order; reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for 7s-7p, 7p-6d, and 6d-5f electric-dipole transitions; and 7s-6d, 7s-5f, and 5f{sub 5/2}-5f{sub 7/2} multipole matrix elements are evaluated to obtain the lifetimes of low-lying excited states. Moreover, for the ions Z=87-92 calculations are also carried out using the relativistic all-order single-double method, in which single and double excitations of Dirac-Fock wave functions are included to all orders in perturbation theory. With the aid of the single-double wave functions, we obtain accurate values of energies, transition rates, oscillator strengths, and the lifetimes of these six ions. Ground state scalar polarizabilities in Fr I, Ra II, Ac III, and Th IV are calculated using relativistic third-order and all-order methods. Ground state scalar polarizabilities for other Fr-like ions are calculated using a relativistic second-order method. These calculations provide a theoretical benchmark for comparison with experiment and theory.

  17. Low-power laser induced metal-insulator transition in gold::vanadium dioxide nanoarrays

    NASA Astrophysics Data System (ADS)

    Ferrara, Davon W.; Macquarrie, Evan R.; Nag, Joyeeta; Haglund, Richard F.

    2010-10-01

    Vanadium dioxide (VO2) is a strongly-correlated electron material with a well-known semiconductor-to-metal transition (SMT) that can be induced thermally, optically, or electrically. By coating lithographically prepared arrays of gold nanoparticles (NPs) of diameter 140 nm with a 60 nm thick film of VO2 by pulsed laser deposition, hybrid Au::VO2 structures were created. Due to the sensitivity of the Au particle-plasmon resonance (PPR), a temperature dependent shift in the PPR can be generated by switching the VO2 from one phase to another, creating a tunable plasmonic metamaterial. To study the low-power switching characteristics of these structures, transient absorption measurements were made using a mechanically shuttered 785 nm pump laser, corresponding to the PPR resonance of the Au NPs, and 1550 nm CW probe. Results show that the presence of Au NPs significantly lowers the threshold laser power required to induce the SMT. Measurements on arrays of different grating constants (350 nm and 500 nm) support the hypothesis that the particles are acting as ``nano-radiators'' that absorb and redeposit thermal energy by scattering light back into the film. Finite element modeling was performed to better understand the complex thermodynamics of the structure.

  18. Numerical modeling of transition to turbulence in low-pressure axial gas turbines

    NASA Astrophysics Data System (ADS)

    Flitan, Horia Constantin

    2002-09-01

    Experimental data from modern turbofan engines indicate that the low-pressure turbine stages experience a significant drop in efficiency as the aircraft reaches its cruise conditions at high altitude. Under these circumstances, the low Reynolds number flow allows the apparition of a boundary layer which is no longer turbulent but transitional in nature. A further decrease in velocity may lead to the separation of the highly unstable laminar portion accompanied by a dramatic growth in aerodynamic losses. The methods for numerically simulating the transitional flows occurring over turbine blades were reviewed. Two large categories were identified as suitable for numerical implementation into a fully-implicit, finite-difference, Navier-Stokes code. The first involved a Baldwin-Lomax turbulence model corrected for attached flow transition with an intermittency factor distribution. The general expression of Solomon, Walker and Gostelow was added to the code, in parallel with the zero-pressure gradient form of Narasimha, used for reference. In both cases transition inception is detected with the Abu-Ghannam Shaw correlation. Whenever laminar separation takes place, Robert's correlation for short bubble transition is activated. The second category comprised the two-equation, low Reynolds number turbulence models of Chien and Launder-Sharma. They have a certain ability to predict bypass transition and seem to better comprehend the physics of wake-induced transition. For the approximate factorization solution algorithm, the implicit part of the Launder-Sharma system was expressed in an original form. Also, the Kato-Launder correction was added to be used as an option. Numerical investigations of attached flow bypass transition and separated flow short bubble transitions were performed on two cascade geometries. The Abu-Ghannam Shaw criterion proved to be inaccurate for curved surfaces. The Solomon, Walker Gostelow distribution did not perform better than Narasimha

  19. Improving the Transition Outcomes of Low-Income Minority Youth with Disabilities

    ERIC Educational Resources Information Center

    Balcazar, Fabricio E.; Taylor-Ritzler, Tina; Dimpfl, Shawn; Portillo-Pena, Nelson; Guzman, Alberto; Schiff, Rachel; Murvay, Michele

    2012-01-01

    This study describes the results of a program developed to improve the transition outcomes of low-income minority youth with disabilities. The program relies on case management support to facilitate interagency collaboration. The participants included 164 graduates from special education and 26 youth from an equivalent comparison group. Two case…

  20. The Transition Experiences of High-Achieving, Low-Income Undergraduates in an Elite College Environment

    ERIC Educational Resources Information Center

    McLoughlin, Paul J., II

    2012-01-01

    This hermeneutic phenomenological study describes the lived experiences of high-achieving, low-income undergraduates and their transition into a college environment historically reserved for wealthy students. The results of this study indicate that these students are flourishing in full need-based financial aid programs as a result of their own…

  1. Low energy beam transport system developments

    SciTech Connect

    Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.

    2015-04-08

    For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H{sup −} beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H{sup −} beams, but such gas densities cause unacceptably high H{sup −} beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H{sup −} beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.

  2. Transits

    NASA Astrophysics Data System (ADS)

    Gilliland, Ronald L.

    Transits of the planets Mercury and especially Venus have been exciting events in the development of astronomy over the past few hundred years. Just two years ago the first transiting extra-solar planet, HD 209458b, was discovered, and subsequent studies during transit have contributed fundamental new knowledge. From the photometric light curve during transit one obtains a basic confirmation that the radial velocity detected object is indeed a planet by allowing precise determination of its mass and radius relative to these stellar quantities. From study of spectroscopic changes during transit it has been possible to probe for individual components of the transiting planets atmosphere. Planet transits are likely to become a primary tool for detection of new planets, especially other Earth-like planets with the Kepler Discovery Mission. Looking ahead, the additional aperture of the James Webb Space Space Telescope promises to allow the first possibility of studying the atmosphere of extra-solar Earth-analogue planets, perhaps even providing the first evidence of direct relevance to the search for signs of life on other planets.

  3. Low Energy Antiproton Experiments - A Review

    SciTech Connect

    Jungmann, Klaus P.

    2005-10-19

    Low energy antiprotons offer excellent opportunities to study properties of fundamental forces and symmetries in nature. Experiments with them can contribute substantially to deepen our fundamental knowledge in atomic, nuclear and particle physics. Searches for new interactions can be carried out by studying discrete symmetries. Known interactions can be tested precisely and fundamental constants can be extracted from accurate measurements on free antiprotons (p-bar's) and bound two- and three-body systems such as antihydrogen (H-bar = p-bare-), the antprotonic helium ion (He++p-bar)+ and the antiprotonic atomcule (He++p-bare-) . The trapping of a single p-bar in a Penning trap, the formation and precise studies of antiprotonic helium ions and atoms and recently the production of H-bar have been among the pioneering experiments. They have led already to precise values for p-bar parameters, accurate tests of bound two- and three-body Quantum Electrodynamics (QED), tests of the CPT theorem and a better understanding of atom formation from their constituents. Future experiments promise more precise tests of the standard theory and have a robust potential to discover new physics. Precision experiments with low energy p-bar's share the need for intense particle sources and the need for time to develop novel instrumentation with all other experiments, which aim for high precision in exotic fundamental systems. The experimental programs - carried out in the past mostly at the former LEAR facility and at present at the AD facility at CERN - would benefit from intense future sources of low energy p-bar's. The highest possible p-bar fluxes should be aimed for at new facilities such as the planned FLAIR facility at GSI in order to maximize the potential of delicate precision experiments to influence model building. Examples of key p-bar experiments are discussed here and compared with other experiments in the field. Among the central issues is their potential to obtain

  4. Proceedings of RIKEN BNL Resarch Center Workshop: Fluctuations, Correlations and RHIC Low Energy Runs

    SciTech Connect

    Karsch, F.; Kojo, T.; Mukherjee, S.; Stephanov, M.; Xu, N.

    2011-10-27

    Most of our visible universe is made up of hadronic matter. Quantum Chromodynamics (QCD) is the theory of strong interaction that describes the hadronic matter. However, QCD predicts that at high enough temperatures and/or densities ordinary hadronic matter ceases to exist and a new form of matter is created, the so-called Quark Gluon Plasma (QGP). Non-perturbative lattice QCD simulations shows that for high temperature and small densities the transition from the hadronic to the QCD matter is not an actual phase transition, rather it takes place via a rapid crossover. On the other hand, it is generally believed that at zero temperature and high densities such a transition is an actual first order phase transition. Thus, in the temperature-density phase diagram of QCD, the first order phase transition line emanating from the zero temperature high density region ends at some higher temperature where the transition becomes a crossover. The point at which the first order transition line turns into a crossover is a second order phase transition point belonging to three dimensional Ising universality class. This point is known as the QCD Critical End Point (CEP). For the last couple of years the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been performing experiments at lower energies in search of the elusive QCD CEP. In general critical behaviors are manifested through appearance of long range correlations and increasing fluctuations associated with the presence of mass-less modes in the vicinity of a second order phase transition. Experimental signatures of the CEP are likely to be found in observables related to fluctuations and correlations. Thus, one of the major focuses of the RHIC low energy scan program is to measure various experimental observables connected to fluctuations and correlations. On the other hand, with the start of the RHIC low energy scan program, a flurry of activities are taking place to provide solid theoretical

  5. Low-energy electric dipole response of Sn isotopes

    NASA Astrophysics Data System (ADS)

    Papakonstantinou, P.; Hergert, H.; Ponomarev, V. Yu.; Roth, R.

    2014-03-01

    We study the low-energy dipole (LED) strength distribution along the Sn isotopic chain in both the isoscalar (IS) and the isovector (IV, or E1) electric channels, to provide testable predictions and guidance for new experiments with stable targets and radioactive beams. We use the self-consistent quasi-particle random-phase approximation (QRPA) with finite-range interactions and mainly the Gogny D1S force. We analyze also the performance of a realistic two-body interaction supplemented by a phenomenological three-body contact term. We find that from N =50 and up to the N =82 shell closure (132Sn) the lowest-energy part of the IS-LED spectrum is dominated by a collective transition whose properties vary smoothly with neutron number and which cannot be interpreted as a neutron-skin oscillation. For the neutron-rich species this state contributes to the E1 strength below particle threshold, but much more E1 strength is carried by other, weak but numerous transitions around or above threshold. We find that strong structural changes in the spectrum take effect beyond N =82, namely increased LED strength and lower excitation energies. Our results with the Gogny interaction are compatible with existing data. On this basis we predict that (a) the summed IS strength below particle threshold shall be of the same order of magnitude for N =50-82, (b) the summed E1 strength up to approximately 12 MeV shall be similar for N =50-82 MeV, while (c) the summed E1 strength below threshold shall be of the same order of magnitude for N ≈64-82 and much weaker for the lighter, more-symmetric isotopes. We point out a general agreement of our results with other nonrelativistic studies, the absence of a collective IS mode in some of those studies, and a possibly radical disagreement with relativistic models.

  6. Phenomenological implications of low energy supersymmetry breaking

    SciTech Connect

    Dimopoulos, S. |; Dine, M.; Raby, S.; Thomas, S.; Wells, J.D.

    1996-07-01

    The experimental signatures for low energy supersymmetry breaking are presented. The lightest standard model superpartner is unstable and decays to its partner plus a Goldstino, G. For a supersymmetry breaking scale below a few 1,000 TeV this decay can take place within a detector, leading to very distinctive signatures. If a neutralino is the lightest standard model superpartner it decays by {chi}{sub 1}{sup 0} {r_arrow} {gamma} + G, and if kinematically accessible by {chi}{sub 1}{sup 0} {r_arrow} (Z{sup 0}, h{sup 0}, H{sup 0}, A{sup 0}) + G. These decays can give rise to displaced vertices. Alternately, if a slepton is the lightest standard model superpartner it decays by {tilde l} {r_arrow} l + G. This can be seen as a greater than minimum ionizing charged particle track, possibly with a kink to a minimum ionizing track.

  7. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J.; Spletzer, Barry L.

    2006-12-12

    A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

  8. The Superconducting Super Collider Low Energy Booster

    SciTech Connect

    York, R.C.; Funk, W.; Garren, A.; Machida, S.; Mahale, N.K.; Peterson, J.; Pilat, F.; Wu, X. ); Wienands, U. )

    1991-05-01

    In collider fill mode, the Low Energy Booster (LEB) will accelerate 10{sup 12} protons in 114 bunches from an injection momentum of 1.22 GeV/c to a final momentum of 12 Gev/c, cycling at a frequency of 10 Hz. The most significant extension of present fast-cycling synchrotron technology arises from the requirement that the normalized transverse emittance (rms) of the beam be {le}0.6 {pi} {mu}m. In an alternative mode, the LEB will accelerate five times this current with a normalized transverse emittance {le} 4 {pi} {mu}m. A general overview of the design is presented. 7 refs., 2 figs., 4 tabs.

  9. Low-energy pion-nucleon scattering

    SciTech Connect

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent {pi}{sup {plus_minus}}p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f{sup 2}=0.0756{plus_minus}0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P{sub 31} and P{sub 13} partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the {Sigma} term. Off-shell amplitudes are also provided. {copyright} {ital 1998} {ital The American Physical Society}

  10. Low-energy pion-nucleon scattering

    NASA Astrophysics Data System (ADS)

    Gibbs, W. R.; Ai, Li; Kaufmann, W. B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent π+/-p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f2=0.0756+/-0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P31 and P13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided.

  11. Electron-impact dissociative double ionization of N2 and CO: Dependence of transition probability on impact energy

    NASA Astrophysics Data System (ADS)

    Pandey, A.; Kumar, P.; Banerjee, S. B.; Subramanian, K. P.; Bapat, B.

    2016-04-01

    We present an experimental and computational analysis of dissociative double ionization of N2 and CO molecules under electron impact. Experiments are performed at three energies, viz. 1, 3, and 5 keV, in order to observe the effect of impact energy on the dissociative ionization kinematics. We compare the kinetic energy release (KER) distributions of the charge symmetric dissociation channels of N22 + and CO2 + at these impact energies. An approximately linear trend between the transition energy and the expected KER values is inferred on the basis of the calculated potential energy curves of the dications. Experimentally, the normalized differential KER cross sections for these channels show an increasing trend in the low KER range and a decreasing trend in the high KER range as the electron-impact energy is increased. This observation indicates that the transition probability for excitation to different molecular ion states is not only a function of energy difference between the ground and excited states, but also a complicated function of the impact energy. In addition, nature of the observed trend in the differential KER cross sections differs significantly from their differential transition probability, which are calculated using inelastic collision model for fast-electron-impact case.

  12. Numerical modeling of the transition from low to high confinement in magnetically confined plasma

    NASA Astrophysics Data System (ADS)

    Rasmussen, J. Juul; Nielsen, A. H.; Madsen, J.; Naulin, V.; Xu, G. S.

    2016-01-01

    The transition dynamics from low (L) to high (H) mode confinement in magnetically confined plasmas is investigated using a four-field drift fluid model—HESEL (Hot Edge-Sol-Electrostatic). The model includes profile evolution and is solved in a 2D domain at the out-board mid-plane of a tokamak including both open and closed field lines. The results reveal different types of L-H-like transitions in response to ramping up the input power by increasing the ion temperature in the edge region. For a fast rising input power we obtain an abrupt transition, and for a slow rising power we obtain a L-I-H transition with an intermediate I-phase displaying limit-cycle oscillations (LCO). The model recovers the power threshold for the L-H transition, the scaling of the threshold with the density and with the loss-rate in the SOL, indicating a decrease in power threshold when switching from single to double null configuration. The results hold promises for developing full predictive modeling of the L-H transition, which is an essential step in understanding and optimizing fusion devices.

  13. Low energy AMS of americium and curium

    NASA Astrophysics Data System (ADS)

    Christl, Marcus; Dai, Xiongxin; Lachner, Johannes; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2014-07-01

    Accelerator mass spectrometry (AMS) has evolved over the past years as one of the most sensitive, selective, and robust techniques for actinide analyses. While analyses of U and Pu isotopes have already become routine at the ETH Zurich 0.5 MV AMS system "Tandy", there is an increasing demand for highly sensitive analyses of the higher actinides such as Am and Cm for bioassay applications and beyond. In order to extend the actinide capabilities of the compact ETH Zurich AMS system and to develop new, more sensitive bioassay routines, a pilot study was carried out. The aim was to investigate and document the performance and the potential background of Am and Cm analyses with low energy AMS. Our results show that 241Am and Cm isotopes can be determined relative to a 243Am tracer if samples and AMS standards are prepared identically with regard to the matrix elements, in which the sample is dispersed. In this first test, detection limits for Cm and Am isotopes are all in the sub-femtogram range and even below 100 ag for Cm isotopes. In a systematic background study in the mass range of the Cm isotopes, two formerly unknown metastable triply charged Th molecules were found on amu(244) and amu(248). The presence of such a background is not a principal problem for AMS if the stripper pressure is increased accordingly. Based on our first results, we conclude that ultra-trace analyses of Am and Cm isotopes for bioassay are very well possible with low energy AMS.

  14. The Low Energy Effective Area of the Chandra Low Energy Transmission Grating Spectrograph

    NASA Technical Reports Server (NTRS)

    Pease, D.; Drake, J. J.; Johnson, C. O.; Kashya, V.; Ratzlaff, P. W.; Wargelin, B. J.; Brinkman, A. C.; Kaastra, J. S.; vanderMeer, R.; Paerels, F. B.

    2000-01-01

    The Chandra X-ray Observatory was successfully launched on July 23, 1999, and subsequently began an intensive calibration phase. We present the preliminary results from the in-flight calibration of the low energy response of the High Resolution Camera spectroscopic readout (HRC-S) combined with the Low Energy Transmission Grating (LETG) aboard Chandra. These instruments comprise the Low Energy Transmission Grating Spectrograph (LETGS). For this calibration study, we employ a pure hydrogen non-LTE white dwarf emission model (T = 25000 K and log g = 9.0) for comparison with the Chandra observations of Sirius B. The pre-flight calibration of the LETGS effective area only covered wavelengths shortward of 44 A (E less than 277 eV). Our Sirius B analysis shows that the HRC-S quantum efficiency (QE) model assumed for longer wavelengths leads to an overestimate of the effective area by an average factor of about 1.6. We derive a correction to the low energy HRC-S QE model to match the predicted and observed Sirius B spectra over the wavelength range of 44-185 A. We make an independent test of our results by the comparison of a Chandra LETGS observation of HZ 43 with pure hydrogen model atmosphere predictions and find good agreement.

  15. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  16. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  17. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  18. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  19. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  20. Optimal Low Energy Earth-Moon Transfers

    NASA Technical Reports Server (NTRS)

    Griesemer, Paul Ricord; Ocampo, Cesar; Cooley, D. S.

    2010-01-01

    The optimality of a low-energy Earth-Moon transfer is examined for the first time using primer vector theory. An optimal control problem is formed with the following free variables: the location, time, and magnitude of the transfer insertion burn, and the transfer time. A constraint is placed on the initial state of the spacecraft to bind it to a given initial orbit around a first body, and on the final state of the spacecraft to limit its Keplerian energy with respect to a second body. Optimal transfers in the system are shown to meet certain conditions placed on the primer vector and its time derivative. A two point boundary value problem containing these necessary conditions is created for use in targeting optimal transfers. The two point boundary value problem is then applied to the ballistic lunar capture problem, and an optimal trajectory is shown. Additionally, the ballistic lunar capture trajectory is examined to determine whether one or more additional impulses may improve on the cost of the transfer.

  1. Excitation of positive ions by low-energy electrons - Relevance to the Io Torus

    NASA Astrophysics Data System (ADS)

    Smith, S. J.; Chutjian, A.; Mawhorter, R. J.; Williams, I. D.; Shemansky, D. E.

    1993-03-01

    The importance of measuring electron-ion excitation cross sections in singly and multiply charged positive ions is outlined, and recent results for Mg II and O II ions are given using the JPL's electron energy-loss merged-beams apparatus. Theoretical comparisons are given with two five-state close-coupling calculations. The energy variation of the collision strength is fitted with a semiempirical analytic function which includes approximations to polarization, resonance, and exchange contributions. In O II, first spectra anywhere of electron excitation of the optically allowed transitions are presented. In addition, excitations of two low lying, optically forbidden transitions are detected for the first time.

  2. SEMICONDUCTOR DEVICES: Low-field mobility and carrier transport mechanism transition in nanoscale MOSFETs

    NASA Astrophysics Data System (ADS)

    Hongwei, Liu; Runsheng, Wang; Ru, Huang; Xing, Zhang

    2010-04-01

    This paper extends the flux scattering method to study the carrier transport property in nanoscale MOSFETs with special emphasis on the low-field mobility and the transport mechanism transition. A unified analytical expression for the low-field mobility is proposed, which covers the entire regime from drift-diffusion transport to quasi-ballistic transport in 1-D, 2-D and 3-D MOSFETs. Two key parameters, namely the long-channel low-field mobility (μ0) and the low-field mean free path (λ0), are obtained from the experimental data, and the transport mechanism transition in MOSFETs is further discussed both experimentally and theoretically. Our work shows that λ0 is available to characterize the inherent transition of the carrier transport mechanism rather than the low-field mobility. The mobility reduces in the MOSFET with the shrinking of the channel length; however, λ0 is nearly a constant, and λ0 can be used as the “entry criterion" to determine whether the device begins to operate under quasi-ballistic transport to some extent.

  3. Surface energy exchanges along a tundra-forest transition and feedbacks to climate

    USGS Publications Warehouse

    Beringer, J.; Chapin, F. S.; Thompson, Catharine Copass; McGuire, A.D.

    2005-01-01

    Surface energy exchanges were measured in a sequence of five sites representing the major vegetation types in the transition from arctic tundra to forest. This is the major transition in vegetation structure in northern high latitudes. We examined the influence of vegetation structure on the rates of sensible heating and evapotranspiration to assess the potential feedbacks to climate if high-latitude warming were to change the distribution of these vegetation types. Measurements were made at Council on the Seward Peninsula, Alaska, at representative tundra, low shrub, tall shrub, woodland (treeline), and boreal forest sites. Structural differences across the transition from tundra to forest included an increase in the leaf area index (LAI) from 0.52 to 2.76, an increase in canopy height from 0.1 to 6.1 m, and a general increase in canopy complexity. These changes in vegetation structure resulted in a decrease in albedo from 0.19 to 0.10 as well as changes to the partitioning of energy at the surface. Bulk surface resistance to water vapor flux remained virtually constant across sites, apparently because the combined soil and moss evaporation decreased while transpiration increased along the transect from tundra to forest. In general, sites became relatively warmer and drier along the transect with the convective fluxes being increasingly dominated by sensible heating, as evident by an increasing Bowen ratio from 0.94 to 1.22. The difference in growing season average daily sensible heating between tundra and forest was 21 W m-2. Fluxes changed non-linearly along the transition, with both shrubs and trees substantially enhancing heat transfer to the atmosphere. These changes in vegetation structure that increase sensible heating could feed back to enhance warming at local to regional scales. The magnitude of these vegetation effects on potential high-latitude warming is two to three times greater than suggested by previous modeling studies. ?? 2005 Elsevier B.V. All

  4. Mixed transition-metal oxides: design, synthesis, and energy-related applications.

    PubMed

    Yuan, Changzhou; Wu, Hao Bin; Xie, Yi; Lou, Xiong Wen David

    2014-02-01

    A promising family of mixed transition-metal oxides (MTMOs) (designated as Ax B3-x O4 ; A, B=Co, Ni, Zn, Mn, Fe, etc.) with stoichiometric or even non-stoichiometric compositions, typically in a spinel structure, has recently attracted increasing research interest worldwide. Benefiting from their remarkable electrochemical properties, these MTMOs will play significant roles for low-cost and environmentally friendly energy storage/conversion technologies. In this Review, we summarize recent research advances in the rational design and efficient synthesis of MTMOs with controlled shapes, sizes, compositions, and micro-/nanostructures, along with their applications as electrode materials for lithium-ion batteries and electrochemical capacitors, and efficient electrocatalysts for the oxygen reduction reaction in metal-air batteries and fuel cells. Some future trends and prospects to further develop advanced MTMOs for next-generation electrochemical energy storage/conversion systems are also presented.

  5. First-order chiral phase transition in high-energy collisions: Can nucleation prevent spinodal decomposition?

    SciTech Connect

    Scavenius, O.; Dumitru, A.; Fraga, E. S.; Lenaghan, J. T.; Jackson, A. D.

    2001-06-01

    We discuss homogeneous nucleation in a first-order chiral phase transition within an effective field theory approach to low-energy QCD. Exact decay rates and bubble profiles are obtained numerically and compared to analytic results obtained with the thin-wall approximation. The thin-wall approximation overestimates the nucleation rate for any degree of supercooling. The time scale for critical thermal fluctuations is calculated and compared to typical expansion times for high-energy hadronic or heavy-ion collisions. We find that significant supercooling is possible, and the relevant mechanism for phase conversion might be that of spinodal decomposition. Some potential experimental signatures of supercooling, such as an increase in the correlation length of the scalar condensate, are also discussed.

  6. Low-temperature fabrication of VO2 thin film on ITO glass with a Mott transition

    NASA Astrophysics Data System (ADS)

    Lin, Tiegui; Wang, Langping; Wang, Xiaofeng; Zhang, Yufen

    2016-09-01

    Polycrystalline Vanadium dioxide (VO2) thin film can be fabricated on glass substrates by high power impulse magnetron sputtering at a relative high temperature. In order to apply an effective bias voltage on substrate and control the energy of the ions impinged to the substrate, conductive indium-tin oxide (ITO) glass was used as the substrate. UV-visible-near IR transmittance spectra and X-ray diffraction (XRD) patterns of the as-deposited films exhibited that M-VO2 thin film with a metal-insulator transition temperature of 37∘C was fabricated successfully at 300∘C with a bias voltage of ‑200V, and the calculated average crystalline size of this film was about 12nm. XRD patterns at varied temperatures showed that the structural change of MIT of the VO2 thin film was suppressed during the phase transition process, and a pure Mott transition was obtained.

  7. Evidence for liquid water during the high-density to low-density amorphous ice transition

    PubMed Central

    Kim, Chae Un; Barstow, Buz; Tate, Mark W.; Gruner, Sol M.

    2009-01-01

    Polymorphism of water has been extensively studied, but controversy still exists over the phase transition between high-density amorphous (HDA) and low-density amorphous (LDA) ice. We report the phase behavior of HDA ice inside high-pressure cryocooled protein crystals. Using X-ray diffraction, we demonstrate that the intermediate states in the temperature range from 80 to 170 K can be reconstructed as a linear combination of HDA and LDA ice, suggesting a first-order transition. We found evidence for a liquid state of water during the ice transition based on the protein crystallographic data. These observations open the possibility that the HDA ice induced by high-pressure cryocooling is a genuine glassy form of high-density liquid. PMID:19258453

  8. Organization versus frustration: low temperature transitions in a gelatine-based gel

    NASA Astrophysics Data System (ADS)

    Philipp, M.; Müller, U.; Sanctuary, R.; Baller, J.; Krüger, J. K.

    2008-09-01

    A commercial physical gel composed of gelatine, water and glycerol shows a sol-gel transition which has been resolved by optical rotation measurements by step-wise heating the gel. This transition is not observable in the longitudinal acoustic mode measured at hypersonic frequencies with Brillouin spectroscopy. Depending on the thermal treatment of the investigated material during the sol-gel transition and within the gel state, Brillouin spectroscopy reflects tremendously different hypersonic dynamics. These distinct dynamics are responsible for the formation of different glassy states at low temperatures including that of a glass-ceramic. The large variety of super-cooled and glassy states is attributed to distinct distributions of the gel's constituents within the samples. Surprisingly, the same gel state can be produced either by annealing the gel over months or by the non-equilibrium effect of thermo-diffusion (Soret effect) in the course of some minutes.

  9. Infrared thermography for detection of laminar-turbulent transition in low-speed wind tunnel testing

    NASA Astrophysics Data System (ADS)

    Joseph, Liselle A.; Borgoltz, Aurelien; Devenport, William

    2016-05-01

    This work presents the details of a system for experimentally identifying laminar-to-turbulent transition using infrared thermography applied to large, metal models in low-speed wind tunnel tests. Key elements of the transition detection system include infrared cameras with sensitivity in the 7.5- to 14.0-µm spectral range and a thin, insulating coat for the model. The fidelity of the system was validated through experiments on two wind-turbine blade airfoil sections tested at Reynolds numbers between Re = 1.5 × 106 and 3 × 106. Results compare well with measurements from surface pressure distributions and stethoscope observations. However, the infrared-based system provides data over a much broader range of conditions and locations on the model. This paper chronicles the design, implementation and validation of the infrared transition detection system, a subject which has not been widely detailed in the literature to date.

  10. Viscosity, glass transition and activation energy of solid cis-polyisoprene and trans-polyisoprene blends

    NASA Astrophysics Data System (ADS)

    Baboo, Mahesh; Sharma, Kananbala; Saxena, N. S.

    2011-11-01

    Blends of cis-polyisoprene (CPI) and trans-polyisoprene (TPI) have been prepared by solution casting to study viscosity, glass transition temperature and activation energy for the glass transition. The viscosity of blends having different weight ratios has been obtained through a single experiment measuring storage and loss modulus using the dynamic mechanical analyser technique. The glass transition temperature is determined through the temperature at which the minimum of temperature derivative curve of viscosity falls. The activation energy of glass transition and fragility index have been obtained by employing the Vogel-Fulchar-Tammann (VFT) equation by assuming non-Arrhenius behaviour of viscosity of polymer blends. Results indicate that both glass transition and activation energy for the glass transition are influenced by composition and crosslink density of the blend.

  11. Critical behavior in the inverse to forward energy transition in two-dimensional magnetohydrodynamic flow.

    PubMed

    Seshasayanan, Kannabiran; Alexakis, Alexandros

    2016-01-01

    We investigate the critical transition from an inverse cascade of energy to a forward energy cascade in a two-dimensional magnetohydrodynamic flow as the ratio of magnetic to mechanical forcing amplitude is varied. It is found that the critical transition is the result of two competing processes. The first process is due to hydrodynamic interactions and cascades the energy to the large scales. The second process couples small-scale magnetic fields to large-scale flows, transferring the energy back to the small scales via a nonlocal mechanism. At marginality the two cascades are both present and cancel each other. The phase space diagram of the transition is sketched.

  12. Europe in the energy transition: the case for a smaller population.

    PubMed

    Grant, L

    1988-07-01

    Europe has not yet reached a sustainable society, that is, like the rest of the world, its people cannot live comfortably within its resources, but, it has achieved stabilizing population growth, a control on a potentially dangerous dependency on imported food, an adjustment to the transition from the colonial era, and a position conducive to deal with the energy transition. Europe is the most densely population region of the world, except for Japan. Concern about depopulation in western Europe is misplaced because European populations are on a plateau not a decline, and a lower population is a benefit when confronting resource and environmental constraints. World oil production is expected to peak and then to decline depending on demand, prices, and technology. European oil production will decline, and the United Kingdom will become a net importer in the mid-1990s. The environmental transition is described as more complex than finding a substitute for oil, in part because Europe, unlike the US, has limited fossil fuel resources which are also less accessible. Biomass as the alternative to fossil fuels must be produced on lands currently in food or forestry production. Also corn and bagasse production is not suited to for growing the European climate. Nuclear energy, with its safety and disposal problems, is only an interim solution. Hydropower development is expensive, and solar power is unsuitable because of the continual cloud cover. Wind power is possible but expensive at low wind levels, and the whole of western Europe is relatively unsuitable. Capital creates wealth, and unemployment is Europe's present problem. Large populations in the current technological revolution do not create greater wealth or military security. Europe and Japan have arrived at the population/energy/environment problem first, and many questions remain as to how to manage the age structure, how to maintain innovation and creativity, and how to maintain a prosperous steady state economy

  13. Europe in the energy transition: the case for a smaller population.

    PubMed

    Grant, L

    1988-07-01

    Europe has not yet reached a sustainable society, that is, like the rest of the world, its people cannot live comfortably within its resources, but, it has achieved stabilizing population growth, a control on a potentially dangerous dependency on imported food, an adjustment to the transition from the colonial era, and a position conducive to deal with the energy transition. Europe is the most densely population region of the world, except for Japan. Concern about depopulation in western Europe is misplaced because European populations are on a plateau not a decline, and a lower population is a benefit when confronting resource and environmental constraints. World oil production is expected to peak and then to decline depending on demand, prices, and technology. European oil production will decline, and the United Kingdom will become a net importer in the mid-1990s. The environmental transition is described as more complex than finding a substitute for oil, in part because Europe, unlike the US, has limited fossil fuel resources which are also less accessible. Biomass as the alternative to fossil fuels must be produced on lands currently in food or forestry production. Also corn and bagasse production is not suited to for growing the European climate. Nuclear energy, with its safety and disposal problems, is only an interim solution. Hydropower development is expensive, and solar power is unsuitable because of the continual cloud cover. Wind power is possible but expensive at low wind levels, and the whole of western Europe is relatively unsuitable. Capital creates wealth, and unemployment is Europe's present problem. Large populations in the current technological revolution do not create greater wealth or military security. Europe and Japan have arrived at the population/energy/environment problem first, and many questions remain as to how to manage the age structure, how to maintain innovation and creativity, and how to maintain a prosperous steady state economy.

  14. Search for light curve modulations among Kepler candidates. Three very low-mass transiting companions

    NASA Astrophysics Data System (ADS)

    Lillo-Box, J.; Ribas, A.; Barrado, D.; Merín, B.; Bouy, H.

    2016-07-01

    Context. Light curve modulations in the sample of Kepler planet candidates allows the disentangling of the nature of the transiting object by photometrically measuring its mass. This is possible by detecting the effects of the gravitational pull of the companion (ellipsoidal modulations) and in some cases, the photometric imprints of the Doppler effect when observing in a broad band (Doppler beaming). Aims: We aim to photometrically unveil the nature of some transiting objects showing clear light curve modulations in the phase-folded Kepler light curve. Methods: We selected a subsample among the large crop of Kepler objects of interest (KOIs) based on their chances to show detectable light curve modulations, i.e., close (a< 12 R⋆) and large (in terms of radius, according to their transit signal) candidates. We modeled their phase-folded light curves with consistent equations for the three effects, namely, reflection, ellipsoidal and beaming (known as REB modulations). Results: We provide detailed general equations for the fit of the REB modulations for the case of eccentric orbits. These equations are accurate to the photometric precisions achievable by current and forthcoming instruments and space missions. By using this mathematical apparatus, we find three close-in very low-mass companions (two of them in the brown dwarf mass domain) orbiting main-sequence stars (KOI-554, KOI-1074, and KOI-3728), and reject the planetary nature of the transiting objects (thus classifying them as false positives). In contrast, the detection of the REB modulations and transit/eclipse signal allows the measurement of their mass and radius that can provide important constraints for modeling their interiors since just a few cases of low-mass eclipsing binaries are known. Additionally, these new systems can help to constrain the similarities in the formation process of the more massive and close-in planets (hot Jupiters), brown dwarfs, and very low-mass companions.

  15. What is a low-energy house and who cares?

    SciTech Connect

    Litt, B.R.

    1994-12-01

    Most energy analysts view low-energy houses as good things, yet differ in their expectations of what exactly a low energy house is. There are two intertwining threads to this report. The first is an evaluation of 50 buildings that have been claimed to be low-energy residences, for which monitored energy performance data have been collected. These data represent the preliminary effort in the ongoing update of the Buildings Energy-Use Compilation and Analysis (BECA) data base for new residences. The second thread concerns the definition of a low-energy house. After the elements of a definition are presented, their implications for actors involved in providing housing are identified. Several more tractable definitions are applied to the houses in this compilation. The outcomes illustrate ways in which different interests are served by various definitions. Different definitions can yield very different energy rankings. No single definition of a low-energy house is universally applicable.

  16. Low-energy electron collisions with thiophene

    NASA Astrophysics Data System (ADS)

    da Costa, R. F.; Varella, M. T. do N.; Lima, M. A. P.; Bettega, M. H. F.

    2013-05-01

    We report on elastic integral, momentum transfer, and differential cross sections for collisions of low-energy electrons with thiophene molecules. The scattering calculations presented here used the Schwinger multichannel method and were carried out in the static-exchange and static-exchange plus polarization approximations for energies ranging from 0.5 eV to 6 eV. We found shape resonances related to the formation of two long-lived π* anion states. These resonant structures are centered at the energies of 1.00 eV (2.85 eV) and 2.82 eV (5.00 eV) in the static-exchange plus polarization (static-exchange) approximation and belong to the B1 and A2 symmetries of the C2v point group, respectively. Our results also suggest the existence of a σ* shape resonance in the B2 symmetry with a strong d-wave character, located at around 2.78 eV (5.50 eV) as obtained in the static-exchange plus polarization (static-exchange) calculation. It is worth to mention that the results obtained at the static-exchange plus polarization level of approximation for the two π* resonances are in good agreement with the electron transmission spectroscopy results of 1.15 eV and 2.63 eV measured by Modelli and Burrow [J. Phys. Chem. A 108, 5721 (2004), 10.1021/jp048759a]. The existence of the σ* shape resonance is in agreement with the observations of Dezarnaud-Dandiney et al. [J. Phys. B 31, L497 (1998), 10.1088/0953-4075/31/11/004] based on the electron transmission spectra of dimethyl(poly)sulphides. A comparison among the resonances of thiophene with those of pyrrole and furan is also performed and, altogether, the resonance spectra obtained for these molecules point out that electron attachment to π* molecular orbitals is a general feature displayed by these five-membered heterocyclic compounds.

  17. LINKING Lyα AND LOW-IONIZATION TRANSITIONS AT LOW OPTICAL DEPTH

    SciTech Connect

    Jaskot, A. E.; Oey, M. S.

    2014-08-20

    We suggest that low optical depth in the Lyman continuum (LyC) may relate the Lyα emission, C II and Si II absorption, and C II* and Si II* emission seen in high-redshift galaxies. We base this analysis on Hubble Space Telescope Cosmic Origins Spectrograph spectra of four Green Pea (GP) galaxies, which may be analogs of z > 2 Lyα emitters (LAEs). In the two GPs with the strongest Lyα emission, the Lyα line profiles show reduced signs of resonant scattering. Instead, the Lyα profiles resemble the Hα line profiles of evolved star ejecta, suggesting that the Lyα emission originates from a low column density and similar outflow geometry. The weak C II absorption and presence of non-resonant C II* emission in these GPs support this interpretation and imply a low LyC optical depth along the line of sight. In two additional GPs, weak Lyα emission and strong C II absorption suggest a higher optical depth. These two GPs differ in their Lyα profile shapes and C II* emission strengths, however, indicating different inclinations of the outflows to our line of sight. With these four GPs as examples, we explain the observed trends linking Lyα, C II, and C II* in stacked LAE spectra, in the context of optical depth and geometric effects. Specifically, in some galaxies with strong Lyα emission, a low LyC optical depth may allow Lyα to escape with reduced scattering. Furthermore, C II absorption, C II* emission, and Lyα profile shape can reveal the optical depth, constrain the orientation of neutral outflows in LAEs, and identify candidate LyC emitters.

  18. The Low-Energy State ofCirculating Stored Ion Beams: Crystalline Beams

    SciTech Connect

    Wei, J.; Li, X.-P.; Sessler, Andrew M.

    1994-03-10

    Molecular dynamics is employed to study the low energy states of a beam of charged particles subject to circumferentially varying guiding and focusing forces and with Coulomb forces between the particles. In a constant gradient ring, the lowest energy state is never ordered, but in an alternating gradient structure, operating below the transition energy, the lowest state is ordered. The nature and characteristics of the ground state depends upon the beam density and the ring parameters. For zero temperature the crystal remains intact for a very long time, but at nonzero temperatures it gains energy from the lattice. A critical temperature exists above which the crystal melts rapidly.

  19. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Brune, Carl R; Grimes, Steven M

    2006-03-30

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between 1 January 2003 and 31 December 2005 and supported by U.S. DOE grant number DE-FG03-03NA00074. Cross sections measured with high resolution have been subjected to an Ericson theory analysis to infer information about the nuclear level density. Other measurements were made of the spectral shape of particles produced in evaporation processes; these also yield level density information. A major project was the development of a new Hauser-Feshbach code for analyzing such spectra. Other measurements produced information on the spectra of gamma rays emitted in reactions on heavy nuclei and gave a means of refining our understanding of gamma-ray strength functions. Finally,reactions on light nuclei were studied and subjected to an R-matrix analysis. Cross sections fora network of nuclear reactions proceedingthrough a given compound nucleus shouldgreatly constrain the family of allowed parameters. Modifications to the formalism andcomputer code are also discussed.

  20. Low energy scattering with a nontrivial pion

    SciTech Connect

    Fariborz, Amir H.

    2007-12-01

    An earlier calculation in a generalized linear sigma model showed that the well-known current algebra formula for low energy pion-pion scattering held even though the massless Nambu Goldstone pion contained a small admixture of a two-quark two-antiquark field. Here we turn on the pion mass and note that the current algebra formula no longer holds exactly. We discuss this small deviation and also study the effects of a SU(3) symmetric quark mass type term on the masses and mixings of the eight SU(3) multiplets in the model. We calculate the s-wave scattering lengths, including the beyond current algebra theorem corrections due to the scalar mesons, and observe that the effect of the scalar mesons is to improve the agreement with experiment. In the process, we uncover the way in which linear sigma models give controlled corrections (due to the presence of scalar mesons) to the current algebra scattering formula. Such a feature is commonly thought to exist only in the nonlinear sigma model approach.

  1. Low Energy Electron Scattering from Fuels

    NASA Astrophysics Data System (ADS)

    Lopes, M. Cristina A.

    2012-06-01

    We report an investigation of processes that occur during the ignition of the plasma and its consequences in post-discharge time for an internal combustion engine, in order to find the appropriate parameters to be used in cars that operate with lean mixtures air-fuel. The relevance of this theme has attracted much attention, and has been one of the subjects of collaboration between experimental and theoretical groups in the USA and Brazil. We have produced some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules were obtained, using the linear transmission method based on the Beer-Lambert law to first approximation. Measurements and calculations of differential cross sections for low-energy (rotationally unresolved) electron scattering were also obtained, for scattering angles of 5 --130 . The measurements were taken using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Additionally to these, computer simulation studies of electronic discharge in mixtures of ethanol were performed, using a Zero-Dimensional Plasma Kinetic solver. Previous reported models for combustion of ethanol and cross sections data for momentum transfer of electron collisions with ethanol were used. The time evolutions of the main species densities are reported and the ignition time delay discussed.

  2. Low Energy Transfer to the Moon

    NASA Astrophysics Data System (ADS)

    Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

    2001-11-01

    New space missions are increasingly more complex; demand for exotic orbits to solve engineering problems has grown beyond the existing astrodynamic infrastructure based on two-body interactions. The delicate heteroclinic dynamics used by the Genesis Mission dramatically illustrate the need for a new paradigm: dynamical system study of three-body problem. Furthermore, this dynamics has much to say about the morphology and transport of materials within the Solar System. The cross-fertilization of ideas between the natural dynamics of the Solar System and applications to engineering has produced new techniques for constructing spacecraft trajectories with interesting characteristics. Specifically, these techniques are used here to produce a lunar capture mission which uses less fuel than a Hohmann transfer. We approximate the Sun-Earth-Moon-Spacecraft four-body problem as two three-body problems. Using the invariant manifold structures of the Lagrange points of the three-body systems, we are able to construct low energy transfer trajectories from the Earth which exhibit ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations. This is joint work with Martin W. Lo, Jerrold E. Marsden and Shane D. Ross and was partially supported by the National Science Foundation Grant No. KFI/ATM-9873133 under a contract with the Jet Propulsion Laboratory, NASA.

  3. Energy surface and minimum energy paths for Fréedericksz transitions in bistable cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Ivanov, A. V.; Bessarab, P. F.; Aksenova, E. V.; Romanov, V. P.; Uzdin, V. M.

    2016-04-01

    The multidimensional energy surface of a cholesteric liquid crystal in a planar cell is investigated as a function of spherical coordinates determining the director orientation. Minima on the energy surface correspond to the stable states with particular director distribution. External electric and magnetic fields deform the energy surface and positions of minima. It can lead to the transitions between states, known as the Fréedericksz effect. Transitions can be continuous or discontinuous depending on parameters of the liquid crystal which determine an energy surface. In a case of discontinuous transition when a barrier between stable states is comparable with the thermal energy, the activation transitions may occur, and it leads to the modification of characteristics of the Fréedericksz effect with temperature without explicit temperature dependencies of liquid crystal parameters. A minimum energy path between stable states on the energy surface for the Fréedericksz transition is found using the geodesic nudged elastic band method. Knowledge of this path, which has maximal statistical weight among all other paths, gives the information about a barrier between stable states and configuration of director orientation during the transition. It also allows one to estimate the stability of states with respect to the thermal fluctuations and their lifetime when the system is close to the Fréedericksz transition.

  4. Compressible DNS of transitional and turbulent flow in a low pressure turbine cascade

    NASA Astrophysics Data System (ADS)

    Ranjan, Rajesh; Deshpande, Suresh; Narasimha, Roddam

    2015-11-01

    Direct numerical simulation (DNS) of flow in a low pressure turbine cascade at high incidence is performed using a new in-house code ANUROOP. This code solves compressible Navier-Stokes equations in conservative form using finite volume technique and uses kinetic-energy consistent scheme for the flux calculations. ANUROOP is capable of handling flow past complex geometries using hybrid grid approach (separate grid topologies for the boundary layer and rest of the blade passage). This approach offers much more control in mesh spacing and distribution compared to elliptic grid technique, which is used in many previous studies. Also, in contrast to previous studies, focus of the current work is mainly on the boundary layer flow. The flow remains laminar on the pressure side of the blade, but separates in the aft region of the suction side leading to transition. Separation bubbles formed at this region are transient in nature and we notice multiple bubbles merging and breaking in time. In the mean flow however, only one bubble is seen. Velocity profiles very near to the leading edge of the suction side suggest strong curvature effect. Higher-order boundary layer theory that includes effect of curvature is found to be necessary to characterize the flow in this region. Also, the grid convergence study reveals interesting aspects of numerics vital for accurate simulation of this kind of complex flows. We would like to thank the Gas Turbine Enabling Technology (GATET) Program for funding this project. We also thank C-DAC, Pune and CSIR-4PI, Bangalore for providing computational resources.

  5. Low temperature magnetic phase transition and interlayer coupling in double-wall carbon nanotubes

    SciTech Connect

    Diamantopoulou, A.; Glenis, S.; Likodimos, V.; Guskos, N.

    2014-08-28

    The magnetic properties of double wall carbon nanotubes (DWCNTs) were investigated using electron spin resonance (ESR) spectroscopy. An asymmetric resonance line of low intensity was identified and analyzed by the superimposition of a narrow and a broad metallic lineshape, attributed to the distinct contributions of defect spins located on the inner and outer DWCNTs shells. The spin susceptibilities of both ESR components revealed a ferromagnetic phase transition at low temperatures (T < 10 K) with small variation in the corresponding Curie-Weiss temperatures, approaching closely that of metallic single wall carbon nanotubes. Interlayer coupling between the DWCNT layers is suggested to effectively reduce the difference between the transition temperatures for the inner and outer shells and enhance spin-spin interactions between defect spins via the RKKY-type interaction of localized spins with conduction electrons.

  6. Near-field resonance shifts of ferroelectric barium titanate domains upon low-temperature phase transition

    SciTech Connect

    Döring, Jonathan; Ribbeck, Hans-Georg von; Kehr, Susanne C.; Eng, Lukas M.; Fehrenbacher, Markus

    2014-08-04

    Scattering scanning near-field optical microscopy (s-SNOM) has been established as an excellent tool to probe domains in ferroelectric crystals at room temperature. Here, we apply the s-SNOM possibilities to quantify low-temperature phase transitions in barium titanate single crystals by both temperature-dependent resonance spectroscopy and domain distribution imaging. The orthorhombic-to-tetragonal structural phase transition at 263 K manifests in a change of the spatial arrangement of ferroelectric domains as probed with a tunable free-electron laser. More intriguingly, the domain distribution unravels non-favored domain configurations upon sample recovery to room temperature as explainable by increased sample disorder. Ferroelectric domains and topographic influences are clearly deconvolved even at low temperatures, since complementing our s-SNOM nano-spectroscopy with piezoresponse force microscopy and topographic imaging using one and the same atomic force microscope and tip.

  7. Multiple Ordering Transitions in a Liquid Stabilized by Low Symmetry Structures

    NASA Astrophysics Data System (ADS)

    Ronceray, Pierre; Harrowell, Peter

    2014-01-01

    We present a numerical study of a lattice model of a liquid characterized by a low-symmetry favored local structure. We find that the freezing point is depressed far enough to reveal an exotic liquid-liquid transition characterized by the appearance of an extended chirality, prior to freezing. The ordered liquid can be readily supercooled to zero temperature, as the combination of critical slowing down and competing crystal polymorphs results in a dramatically slow crystallization process. These results provide an explicit scenario by which the ordering of a liquid can proceed via an intermediate liquid-liquid transition, a scenario that may prove helpful in the analysis of low temperature liquids interacting by more realistic interactions.

  8. Multiple ordering transitions in a liquid stabilized by low symmetry structures.

    PubMed

    Ronceray, Pierre; Harrowell, Peter

    2014-01-10

    We present a numerical study of a lattice model of a liquid characterized by a low-symmetry favored local structure. We find that the freezing point is depressed far enough to reveal an exotic liquid-liquid transition characterized by the appearance of an extended chirality, prior to freezing. The ordered liquid can be readily supercooled to zero temperature, as the combination of critical slowing down and competing crystal polymorphs results in a dramatically slow crystallization process. These results provide an explicit scenario by which the ordering of a liquid can proceed via an intermediate liquid-liquid transition, a scenario that may prove helpful in the analysis of low temperature liquids interacting by more realistic interactions. PMID:24483932

  9. Low Temperature Structural Phase Transition of Ba3NaIr2O9

    SciTech Connect

    Conrad, H.; Loye, Z; Kim, S; Macquart, R; Smith, M; Lee, Y; Vogt, T

    2009-01-01

    Single crystal X-ray and synchrotron X-ray powder diffraction have been used to probe the structure of Ba3NaIr2O9 from 300 K down to 20 K. Ba3NaIr2O9 is found to undergo a structural transition from hexagonal symmetry, P63/mmc, at ambient temperature to monoclinic symmetry, C2/c, at low temperature. The evolution of the unit cell volume upon cooling is indicative of a higher order structural transition, and the symmetry breaking becomes apparent as the temperature is decreased. The low temperature monoclinic structure of Ba3NaIr2O9 contains strongly distorted [NaO6] and [IrO6] octahedra in comparison to the room temperature hexagonal structure.

  10. Experimental radial motion to orbital motion transition in cylindrical Langmuir probes in low pressure plasmas

    NASA Astrophysics Data System (ADS)

    Díaz-Cabrera, J. M.; Ballesteros, J.; Fernández Palop, J. I.; Tejero-del-Caz, A.

    2015-04-01

    This article shows a transition in the behavior of the positive ions movement around a cylindrical Langmuir probe which we have experimentally observed in a low pressure plasma. In the case of helium plasma, depending on the plasma conditions, the ion current collected by the probe behaves as predicted by a radial motion theory, by an orbital motion theory, or by none of them when the transition between the two behaviors takes place. In the case of argon and neon plasmas, the ion current is well described by radial motion theories. The knowledge of the positive ions behavior is essential to diagnose the plasma parameters by using the ion saturation zone of the current-voltage characteristic curve. The use of this zone is one of the less intrusive in probe plasma diagnostics methods providing local information about the plasma parameters, since the charge drained from the plasma is very low.

  11. A Framework for Characterizing the Atmospheres of Low-mass Low-density Transiting Planets

    NASA Astrophysics Data System (ADS)

    Fortney, Jonathan J.; Mordasini, Christoph; Nettelmann, Nadine; Kempton, Eliza M.-R.; Greene, Thomas P.; Zahnle, Kevin

    2013-09-01

    We perform modeling investigations to aid in understanding the atmospheres and composition of small planets of ~2-4 Earth radii, which are now known to be common in our Galaxy. GJ 1214b is a well-studied example whose atmospheric transmission spectrum has been observed by many investigators. Here we take a step back from GJ 1214b to investigate the role that planetary mass, composition, and temperature play in impacting the transmission spectra of these low-mass low-density (LMLD) planets. Under the assumption that these planets accrete modest hydrogen-dominated atmospheres and planetesimals, we use population synthesis models to show that predicted metal enrichments of the H/He envelope are high, with metal mass fraction Z env values commonly 0.6-0.9, or ~100-400+ times solar. The high mean molecular weight of such atmospheres (μ ≈ 5-12) would naturally help to flatten the transmission spectrum of most LMLD planets. The high metal abundance would also provide significant condensible material for cloud formation. It is known that the H/He abundance in Uranus and Neptune decreases with depth, and we show that atmospheric evaporation of LMLD planets could expose atmospheric layers with gradually higher Z env. However, values of Z env close to solar composition can also arise, so diversity should be expected. Photochemically produced hazes, potentially due to methane photolysis, are another possibility for obscuring transmission spectra. Such hazes may not form above T eq of ~800-1100 K, which is testable if such warm, otherwise low mean molecular weight atmospheres are stable against atmospheric evaporation. We find that available transmission data are consistent with relatively high mean molecular weight atmospheres for GJ 1214b and "warm Neptune" GJ 436b. We examine future prospects for characterizing GJ 1214b with Hubble and the James Webb Space Telescope.

  12. A FRAMEWORK FOR CHARACTERIZING THE ATMOSPHERES OF LOW-MASS LOW-DENSITY TRANSITING PLANETS

    SciTech Connect

    Fortney, Jonathan J.; Nettelmann, Nadine; Mordasini, Christoph; Kempton, Eliza M.-R.; Greene, Thomas P.; Zahnle, Kevin

    2013-09-20

    We perform modeling investigations to aid in understanding the atmospheres and composition of small planets of ∼2-4 Earth radii, which are now known to be common in our Galaxy. GJ 1214b is a well-studied example whose atmospheric transmission spectrum has been observed by many investigators. Here we take a step back from GJ 1214b to investigate the role that planetary mass, composition, and temperature play in impacting the transmission spectra of these low-mass low-density (LMLD) planets. Under the assumption that these planets accrete modest hydrogen-dominated atmospheres and planetesimals, we use population synthesis models to show that predicted metal enrichments of the H/He envelope are high, with metal mass fraction Z{sub env} values commonly 0.6-0.9, or ∼100-400+ times solar. The high mean molecular weight of such atmospheres (μ ≈ 5-12) would naturally help to flatten the transmission spectrum of most LMLD planets. The high metal abundance would also provide significant condensible material for cloud formation. It is known that the H/He abundance in Uranus and Neptune decreases with depth, and we show that atmospheric evaporation of LMLD planets could expose atmospheric layers with gradually higher Z{sub env}. However, values of Z{sub env} close to solar composition can also arise, so diversity should be expected. Photochemically produced hazes, potentially due to methane photolysis, are another possibility for obscuring transmission spectra. Such hazes may not form above T{sub eq} of ∼800-1100 K, which is testable if such warm, otherwise low mean molecular weight atmospheres are stable against atmospheric evaporation. We find that available transmission data are consistent with relatively high mean molecular weight atmospheres for GJ 1214b and 'warm Neptune' GJ 436b. We examine future prospects for characterizing GJ 1214b with Hubble and the James Webb Space Telescope.

  13. Linking Lyα and Low-ionization Transitions at Low Optical Depth

    NASA Astrophysics Data System (ADS)

    Jaskot, A. E.; Oey, M. S.

    2014-08-01

    We suggest that low optical depth in the Lyman continuum (LyC) may relate the Lyα emission, C II and Si II absorption, and C II* and Si II* emission seen in high-redshift galaxies. We base this analysis on Hubble Space Telescope Cosmic Origins Spectrograph spectra of four Green Pea (GP) galaxies, which may be analogs of z > 2 Lyα emitters (LAEs). In the two GPs with the strongest Lyα emission, the Lyα line profiles show reduced signs of resonant scattering. Instead, the Lyα profiles resemble the Hα line profiles of evolved star ejecta, suggesting that the Lyα emission originates from a low column density and similar outflow geometry. The weak C II absorption and presence of non-resonant C II* emission in these GPs support this interpretation and imply a low LyC optical depth along the line of sight. In two additional GPs, weak Lyα emission and strong C II absorption suggest a higher optical depth. These two GPs differ in their Lyα profile shapes and C II* emission strengths, however, indicating different inclinations of the outflows to our line of sight. With these four GPs as examples, we explain the observed trends linking Lyα, C II, and C II* in stacked LAE spectra, in the context of optical depth and geometric effects. Specifically, in some galaxies with strong Lyα emission, a low LyC optical depth may allow Lyα to escape with reduced scattering. Furthermore, C II absorption, C II* emission, and Lyα profile shape can reveal the optical depth, constrain the orientation of neutral outflows in LAEs, and identify candidate LyC emitters. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs GO-13293 and GO-12928.

  14. PIV Measurements of Separation and Transition in a Low Pressure Turbine Blade Cascade Model

    NASA Astrophysics Data System (ADS)

    Hollon, Brian; Jacob, Jamey

    2001-11-01

    The flow around a low pressure turbine blade cascade has been investigated with PIV. The purpose of these experiments is to study in detail the flow characteristics within the regions of transition and separation over the suction side of a low pressure turbine blade. The locations of separation, transition, and reattachment, as well as the size of the separation bubble, are studied for a range of Re from 3\\cdot10^4 to 3\\cdot10^5, Free Stream Turbulence Intensities (FSTI) from ~0.5% to ~10%, and exit angle 93^circ to 97^circ. The experiments were conducted in a cascade consisting of 6 PAK-B turbine blades in a low-speed wind tunnel. PIV measurements were acquired in and around the region of separation enabling the determination of important flow characteristics such as skin friction and vorticity in the separation region, and the steadiness of the reversed flow may also be observed. In addition to the PIV study, a smoke-wire technique was employed for flow visualization from Re=3\\cdot10^4 to 9\\cdot10^4, and pressure taps at mid-span along the suction surface of the center blade were used to obtain pressure measurements at 24 stations. The locations of separation and transition have been surmised from the smoke-wire images and the pressure measurements and are presented along with the PIV results.

  15. Nonequilibrium self-energy functional approach to the dynamical Mott transition

    NASA Astrophysics Data System (ADS)

    Hofmann, Felix; Eckstein, Martin; Potthoff, Michael

    2016-06-01

    The real-time dynamics of the Fermi-Hubbard model, driven out of equilibrium by quenching or ramping the interaction parameter, is studied within the framework of the nonequilibrium self-energy functional theory. A dynamical impurity approximation with a single auxiliary bath site is considered as a reference system, and the time-dependent hybridization is optimized as prescribed by the variational principle. The dynamical two-site approximation turns out to be useful to study the real-time dynamics on short and intermediate time scales. Depending on the strength of the interaction in the final state, two qualitatively different response regimes are observed. For both weak and strong couplings, qualitative agreement with previous results of nonequilibrium dynamical mean-field theory is found. The two regimes are sharply separated by a critical point at which the low-energy bath degree of freedom decouples in the course of time. We trace the dependence of the critical interaction of the dynamical Mott transition on the duration of the interaction ramp from sudden quenches to adiabatic dynamics and therewith link the dynamical to the equilibrium Mott transition.

  16. General approach for studying first-order phase transitions at low temperatures.

    PubMed

    Fiore, C E; da Luz, M G E

    2011-12-01

    By combining different ideas, a general and efficient protocol to deal with discontinuous phase transitions at low temperatures is proposed. For small T's, it is possible to derive a generic analytic expression for appropriate order parameters, whose coefficients are obtained from simple simulations. Once in such regimes simulations by standard algorithms are not reliable; an enhanced tempering method, the parallel tempering-accurate for small and intermediate system sizes with rather low computational cost-is used. Finally, from finite size analysis, one can obtain the thermodynamic limit. The procedure is illustrated for four distinct models, demonstrating its power, e.g., to locate coexistence lines and the phase density at the coexistence.

  17. Room temperature homogeneous flow in a bulk metallic glass with low glass transition temperature

    SciTech Connect

    Zhao, K.; Xia, X. X.; Bai, H. Y.; Zhao, D. Q.; Wang, W. H.

    2011-04-04

    We report a high entropy metallic glass of Zn{sub 20}Ca{sub 20}Sr{sub 20}Yb{sub 20}(Li{sub 0.55}Mg{sub 0.45}){sub 20} via composition design that exhibiting remarkable homogeneous deformation without shear banding under stress at room temperature. The glass also shows properties such as low glass transition temperature (323 K) approaching room temperature, low density and high specific strength, good conductivity, polymerlike thermoplastic manufacturability, and ultralow elastic moduli comparable to that of bones. The alloy is thermally and chemically stable.

  18. Energy and Greenhouse Gas Emissions in China: Growth, Transition, and Institutional Change

    NASA Astrophysics Data System (ADS)

    Kahrl, Fredrich James

    Global energy markets and climate change in the twenty first century depend, to an extraordinary extent, on China. China is now, or will soon be, the world's largest energy consumer. Since 2007, China has been the world's largest emitter of greenhouse gases (GHGs). Despite its large and rapidly expanding influence on global energy markets and the global atmosphere, on a per capita basis energy consumption and GHG emissions in China are low relative to developed countries. The Chinese economy, and with it energy use and GHG emissions, are expected to grow vigorously for at least the next two decades, raising a question of critical historical significance: How can China's economic growth imperative be meaningfully reconciled with its goals of greater energy security and a lower carbon economy? Most scholars, governments, and practitioners have looked to technology---energy efficiency, nuclear power, carbon capture and storage---for answers to this question. Alternatively, this study seeks to root China's future energy and emissions trajectory in the political economy of its multiple transitions, from a centrally planned to a market economy and from an agrarian to a post-industrial society. The study draws on five case studies, each a dedicated chapter, which are organized around three perspectives on energy and GHG emissions: the macroeconomy; electricity supply and demand; and nitrogen fertilizer production and use. Chapters 2 and 3 examine how growth and structural change in China's macroeconomy have shaped energy demand, finding that most of the dramatic growth in the country's energy use over the 2000s was driven by an acceleration of its investment-dominated, energy-intensive growth model, rather than from structural change. Chapters 4 and 5 examine efforts to improve energy efficiency and increase the share of renewable generation in the electric power sector, concluding that China's power system lacks the flexibility in generation, pricing, and demand to

  19. Experimental Study of Transitional Flow Behavior in a Simulated Low Pressure Turbine

    NASA Technical Reports Server (NTRS)

    Sohn, Ki Hyeon; DeWitt, Kenneth J.

    2007-01-01

    A detailed investigation of the flow physics occurring on the suction side of a simulated Low Pressure Turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the pressure distribution of an actual LPT airfoil onto a flat lower plate. The experiments were carried out for the Reynolds numbers of 35,000, 70,000, 100,000, and 250,000 with four levels of freestream turbulence ranging from 1 to 4 percent. For the three lower Reynolds numbers, the boundary layer on the flat plate was separated and formed a bubble. The size of laminar separation bubble was measured to be inversely proportional to the freestream turbulence levels and Reynolds numbers. However, no separation was observed for the Re = 250,000 case. The transition on a separated flow was found to proceed through the formation of turbulent spots in the free shear layer as evidenced in the intermittency profiles for Re = 35,000, 70,000, and 100,000. Spectral data show no evidence of Kelvin-Helmholtz of Tollmien-Schlichting instability waves in the free shear layer over a separation bubble (bypass transition). However, the flow visualization revealed the large vortex structures just outside of the bubble and their development to turbulent flow for Re = 50,000, which is similar to that in the free shear layer (separated-flow transition). Therefore, it is fair to say that the bypass and separated-flow transition modes coexist in the transition flows over the separation bubble of certain conditions. Transition onset and end locations and length determined from intermittency profiles decreased as Reynolds number and freestream turbulence levels increase.

  20. Experimental Study of Transitional Flow Behavior in a Simulated Low Pressure Turbine

    NASA Technical Reports Server (NTRS)

    Sohn, Ki Hyeon; DeWitt, Kenneth J.

    1998-01-01

    A detailed investigation of the flow physics occurring on the suction side of a simulated Low Pressure Turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the pressure distribution of an actual LPT airfoil onto a flat lower plate. The experiments were carried out for the Reynolds numbers of 35,000, 70,000, 100,000 and 250,000 with four levels of freestream turbulence ranging from 1% to 4%. For the three lower Reynolds numbers, the boundary layer on the flat plate was separated and formed a bubble. The size of laminar separation bubble was measured to be inversely proportional to the freestream turbulence levels and Reynolds numbers. However, no separation was observed for the Re = 250,000 case. The transition on a separated flow was found to proceed through the formation of turbulent spots in the free shear layer as evidenced in the intermittency profiles for Re = 35,000, 70,000 and 100,000. Spectral data show no evidence of Kelvin-Helmholtz or Tollmien-Schlichting instability waves in the free shear layer over a separation bubble (bypass transition). However, the flow visualization revealed the large vortex structures just outside of the bubble and their development to turbulent flow for Re = 50,000, which is similar to that in the free shear layer (separated-flow transition). Therefore, it is fair to say that the bypass and separated-flow transition modes coexist in the transitional flows over the separation bubble for certain conditions. Transition onset and end locations and length determined from intermittency profiles decrease as Reynolds number and freestream turbulence levels increase.

  1. Low energy availability in the marathon and other endurance sports.

    PubMed

    Loucks, Anne B

    2007-01-01

    Energy availability is the amount of dietary energy remaining after exercise training for all other metabolic processes. Excessively low energy availability impairs reproductive and skeletal health, although genetics and age may alter an individual's initial conditions and sensitivity when low energy availability is imposed. Many marathon runners and other endurance athletes reduce energy availability either (i) intentionally to modify body size and composition for improving performance; (ii) compulsively in a psychopathological pattern of disordered eating; or (iii) inadvertently because there is no strong biological drive to match energy intake to activity-induced energy expenditure. Inadvertent low energy availability is more extreme when consuming a low fat, high carbohydrate diet. Low energy availability, reproductive disorders, low bone mineral density and stress fractures are more common in female than male athletes. Functional menstrual disorders caused by low energy availability should be diagnosed by excluding diseases that also disrupt menstrual cycles. To determine energy availability (in units of kilocalories or kilojoules per kilogram of fat-free mass), athletes can record their diets and use diet analysis software to calculate energy intake, measure energy expenditure during exercise using a heart monitor and measure fat-free mass using a bioelectrical impedance body composition scale. All are commercially available at consumer prices.

  2. Comparative evaluation of energy management models for transit systems. Final report Sep 80-Dec 83

    SciTech Connect

    Nene, V.D.

    1984-02-01

    Recent advances in solid state control technology have led to chopper-controlled propulsion systems in urban rail transit applications. Such systems offer the potential for superior train performance through increased train propulsion efficiency and reduced train operating costs. The present program sponsored by the Urban Mass Transportation Administration studies the energy consumption characteristics of an urban rail system equipped with transit cars having solid-state chopper-controlled propulsion systems. The program objectives include the measurement of the transit system energy consumption during revenue and nonrevenue service operation and the study of the relative accuracy of current energy management models for predicting energy consumption in urban rail systems. This report summarizes the program accomplishments in the Bay Area Rapid Transit (BART) energy consumption tests and the validation of energy management models developed by private industry. The energy consumption of BART transit cars was measured with and without regeneration during the period of August 25, 1981 through September 2, 1981. The test data was then compared with the predictions of different energy management models currently in use for transit system studies. This report presents the results of the comparative evaluation of these models.

  3. Large impact of reorganization energy on photovoltaic conversion due to interfacial charge-transfer transitions.

    PubMed

    Fujisawa, Jun-ichi

    2015-05-14

    Interfacial charge-transfer (ICT) transitions are expected to be a novel charge-separation mechanism for efficient photovoltaic conversion featuring one-step charge separation without energy loss. Photovoltaic conversion due to ICT transitions has been investigated using several TiO2-organic hybrid materials that show organic-to-inorganic ICT transitions in the visible region. In applications of ICT transitions to photovoltaic conversion, there is a significant problem that rapid carrier recombination is caused by organic-inorganic electronic coupling that is necessary for the ICT transitions. In order to solve this problem, in this work, I have theoretically studied light-to-current conversions due to the ICT transitions on the basis of the Marcus theory with density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. An apparent correlation between the reported incident photon-to-current conversion efficiencies (IPCE) and calculated reorganization energies was clearly found, in which the IPCE increases with decreasing the reorganization energy consistent with the Marcus theory in the inverted region. This activation-energy dependence was systematically explained by the equation formulated by the Marcus theory based on a simple excited-state kinetic scheme. This result indicates that the reduction of the reorganization energy can suppress the carrier recombination and enhance the IPCE. The reorganization energy is predominantly governed by the structural change in the chemical-adsorption moiety between the ground and ICT excited states. This work provides crucial knowledge for efficient photovoltaic conversion due to ICT transitions.

  4. Computational Analysis of Energy Pooling to Harvest Low-Energy Solar Energy in Organic Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Lacount, Michael; Shaheen, Sean; Rumbles, Garry; van de Lagemaat, Jao; Hu, Nan; Ostrowski, Dave; Lusk, Mark

    2014-03-01

    Current photovoltaic energy conversions do not typically utilize low energy sunlight absorption, leaving large sections of the solar spectrum untapped. It is possible, though, to absorb such radiation, generating low-energy excitons, and then pool them to create higher energy excitons, which can result in an increase in efficiency. Calculation of the rates at which such upconversion processes occur requires an accounting of all possible molecular quantum electrodynamics (QED) pathways. There are two paths associated with the upconversion. The cooperative mechanism involves a three-body interaction in which low energy excitons are transferred sequentially onto an acceptor molecule. The accretive pathway, requires that an exciton transfer its energy to a second exciton that subsequently transfers its energy to the acceptor molecule. We have computationally modeled both types of molecular QED obtaining rates using a combination of DFT and many-body Green function theory. The simulation platform is exercised by considering upconversion events associated with material composed of a high energy absorbing core of hexabenzocoronene (HBC) and low energy absorbing arms of oligothiophene. In addition, we make estimates for all competing processes in order to judge the relative efficiencies of these two processes.

  5. Approaches to Electric Utility Energy Efficiency for Low Income Customers in a Changing Regulatory Environment

    SciTech Connect

    Brockway, N.

    2001-05-21

    As the electric industry goes through a transformation to a more market-driven model, traditional grounds for utility energy efficiency have come under fire, undermining the existing mechanisms to fund and deliver such services. The challenge, then, is to understand why the electric industry should sustain investments in helping low-income Americans use electricity efficiently, how such investments should be made, and how these policies can become part of the new electric industry structure. This report analyzes the opportunities and barriers to leveraging electric utility energy efficiency assistance to low-income customers during the transition of the electric industry to greater competition.

  6. Energy harvesting from localized dynamic transitions in post-buckled elastic beams under quasi-static loading

    NASA Astrophysics Data System (ADS)

    Borchani, Wassim

    The deployability of structural health monitoring self-powered sensors relies on their capability to harvest energy from signals being monitored. Many of the signals required to assess the structure condition are quasi-static events which limits the levels of power that can be extracted. Several vibration-based techniques have been proposed to increase the transferred level of power and broaden the harvester operating bandwidth. However, these techniques require vibration input excitations at frequencies higher than dominant structural response frequencies which makes them inefficient and not suitable for ambient quasi-static excitations. This research proposes a novel sensing and energy harvesting technique at low frequencies using mechanical energy concentrators and triggers. These mechanisms consist of axially-loaded bilaterally-constrained beams with attached piezoelectric energy harvesters. When the quasi-static axial load reaches a certain mechanical threshold, a sudden snap-through mode-switching occurs. These transitions excite the attached piezoelectric scavengers with high-rate input accelerations, generating then electric power. The main objectives are to understand and model the post-buckling behavior of bilaterally-constrained beams, control it by tailoring geometry and material properties of the buckled elements or stacking them into system assemblies, and finally characterize the energy harvesting and sensing capability of the system under quasi-static excitations. The fundamental principle relies on the following concept. Under axial load, a straight slender beam buckles in the first buckling mode. The increased transverse deformations from a buckled shape lead to contact interaction with the lateral boundaries. The contact interaction generates transverse forces that induce the development of higher order buckling configurations. Transitions between the buckled configurations occur not only during loading, but also unloading. In this work, the post

  7. Low cost solar energy collection system

    NASA Technical Reports Server (NTRS)

    Miller, C. G.; Stephans, J. B. (Inventor)

    1977-01-01

    A fixed, linear, ground-based primary reflector having an extended, curved sawtooth contoured surface covered with a metallized polymeric reflecting material, reflected solar energy to a movably supported collector that was kept at the concentrated line focus of the reflector primary. Efficient utilization leading to high temperatures from the reflected solar energy was obtained by cylindrical shaped secondary reflectors that directed off-angle energy to the absorber pipe.

  8. Low-frequency Raman study of the ferroelectric phase transition in a layered CuCl4-based organic-inorganic hybrid

    NASA Astrophysics Data System (ADS)

    Caretta, Antonio; Miranti, Rany; Havenith, Remco W. A.; Rampi, Elia; Donker, Michiel C.; Blake, Graeme R.; Montagnese, Matteo; Polyakov, Alexey O.; Broer, Ria; Palstra, Thomas T. M.; van Loosdrecht, Paul H. M.

    2014-01-01

    The ferroelectric phase transition at TC=340K in (C6H5CH2CH2NH3)2CuCl4 is studied by means of temperature-dependent low-frequency Raman scattering, focusing on the coupling of a low-energy librational mode to the order parameter of the transition. Analysis of the symmetry and characteristics of this mode links the dipolar order to the tilt angle of the organic cations. The thermal evolution of the Raman spectrum demonstrates the displacive component of the phase transition in combination with order-disorder phenomena and the importance of the organic-inorganic interplay to the physical properties of the compound. The ferroelectric properties investigated here can be generalized to the family of layered organic-inorganic hybrids.

  9. Automating the Transition Between Sensorless Motor Control Methods for the NASA Glenn Research Center Flywheel Energy Storage System

    NASA Technical Reports Server (NTRS)

    Fehrmann, Elizabeth A.; Kenny, Barbara H.

    2004-01-01

    The NASA Glenn Research Center (GRC) has been working to advance the technology necessary for a flywheel energy storage system for the past several years. Flywheels offer high efficiency, durability, and near-complete discharge capabilities not produced by typical chemical batteries. These characteristics show flywheels to be an attractive alternative to the more typical energy storage solutions. Flywheels also offer the possibility of combining what are now two separate systems in space applications into one: energy storage, which is currently provided by batteries, and attitude control, which is currently provided by control moment gyroscopes (CMGs) or reaction wheels. To date, NASA Glenn research effort has produced the control algorithms necessary to demonstrate flywheel operation up to a rated speed of 60,000 RPM and the combined operation of two flywheel machines to simultaneously provide energy storage and single axis attitude control. Two position-sensorless algorithms are used to control the motor/generator, one for low (0 to 1200 RPM) speeds and one for high speeds. The algorithm allows the transition from the low speed method to the high speed method, but the transition from the high to low speed method was not originally included. This leads to a limitation in the existing motor/generator control code that does not allow the flywheels to be commanded to zero speed (and back in the negative speed direction) after the initial startup. In a multi-flywheel system providing both energy storage and attitude control to a spacecraft, speed reversal may be necessary.

  10. Development of a Low-energy Trigger for VERITAS

    SciTech Connect

    Kildea, J.

    2008-12-24

    During the 2007/2008 observing season a low-energy trigger configuration was developed and tested for VERITAS. The configuration makes uses of the small ({approx}35 m) baseline between two of the VERITAS telescopes and employs a much lower discriminator threshold and tighter coincidence window compared to the standard VERITAS trigger. Five hours of Crab Nebula ON/OFF observations were obtained in low-energy mode and were used to test new low-energy analysis algorithms. We present some details of the VERITAS low-energy trigger and the associated data analysis.

  11. Interaction between Low Energy Ions and the Complicated Organism

    NASA Astrophysics Data System (ADS)

    Yu, Zeng-liang

    1999-12-01

    Low energy ions exist widely in natural world, but people pay a little attention on the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy ions and the complicated organism. The discovery of bioeffect induced by ion implantation has, however, opened a new branch in the field of ion beam application in life sciences. This paper reports recent advances in research on the role of low energy ions in chemical synthesis of the biomolecules and application in genetic modification.

  12. Low-Energy Ballistic Transfers to Lunar Halo Orbits

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2009-01-01

    Recent lunar missions have begun to take advantage of the benefits of low-energy ballistic transfers between the Earth and the Moon rather than implementing conventional Hohmann-like lunar transfers. Both Artemis and GRAIL plan to implement low-energy lunar transfers in the next few years. This paper explores the characteristics and potential applications of many different families of low-energy ballistic lunar transfers. The transfers presented here begin from a wide variety of different orbits at the Earth and follow several different distinct pathways to the Moon. This paper characterizes these pathways to identify desirable low-energy lunar transfers for future lunar missions.

  13. Impacts of public transit improvements on ridership, and implications for physical activity, in a low-density Canadian city

    PubMed Central

    Collins, Patricia A.; Agarwal, Ajay

    2015-01-01

    Public transit ridership offers valuable opportunities for modest amounts of daily physical activity (PA). Transit is a more feasible option for most Canadian commuters who live too far from work to walk or cycle, yet public transit usage in midsized Canadian cities has historically remained low due to inefficient transit service. The objectives of this longitudinal study were threefold: to assess whether the introduction of express transit service in the low-density city of Kingston, Ontario, has translated to greater transit use among a targeted employee group; to document the characteristics of those employees that have shifted to transit; and to examine the PA levels of employees using transit compared to other commute modes. An online survey was administered in October 2013 and October 2014 to all non-student employees at Queen's University. 1356 employees completed the survey in 2013, and 1123 in 2014; 656 of these employees completed the survey both years, constituting our longitudinal sample. Year-round transit ridership increased from 5.5% in 2013 to 8.5% in 2014 (p < 0.001). Employees who shifted to transit had fewer household-level opportunities to drive to work and more positive attitudes toward transit. Transit commuters accrued an average of 80 minutes/week of commute-related PA, and 50 minutes/week more total PA than those that commuted entirely passively. Kingston Transit's express service has stimulated an increase in transit ridership among one of their target employers, Queen's University. The findings from this study suggest that shifting to transit from entirely passive commuting can generate higher overall PA levels. PMID:26844163

  14. Impacts of public transit improvements on ridership, and implications for physical activity, in a low-density Canadian city.

    PubMed

    Collins, Patricia A; Agarwal, Ajay

    2015-01-01

    Public transit ridership offers valuable opportunities for modest amounts of daily physical activity (PA). Transit is a more feasible option for most Canadian commuters who live too far from work to walk or cycle, yet public transit usage in midsized Canadian cities has historically remained low due to inefficient transit service. The objectives of this longitudinal study were threefold: to assess whether the introduction of express transit service in the low-density city of Kingston, Ontario, has translated to greater transit use among a targeted employee group; to document the characteristics of those employees that have shifted to transit; and to examine the PA levels of employees using transit compared to other commute modes. An online survey was administered in October 2013 and October 2014 to all non-student employees at Queen's University. 1356 employees completed the survey in 2013, and 1123 in 2014; 656 of these employees completed the survey both years, constituting our longitudinal sample. Year-round transit ridership increased from 5.5% in 2013 to 8.5% in 2014 (p < 0.001). Employees who shifted to transit had fewer household-level opportunities to drive to work and more positive attitudes toward transit. Transit commuters accrued an average of 80 minutes/week of commute-related PA, and 50 minutes/week more total PA than those that commuted entirely passively. Kingston Transit's express service has stimulated an increase in transit ridership among one of their target employers, Queen's University. The findings from this study suggest that shifting to transit from entirely passive commuting can generate higher overall PA levels. PMID:26844163

  15. Low-cost, highly transparent flexible low-e coating film to enable electrochromic windows with increased energy savings

    SciTech Connect

    Berland, Brian; Hollingsworth, Russell

    2015-03-31

    Five Quads of energy are lost through windows annually in the U.S. Low-e coatings are increasingly employed to reduce the wasted energy. Most commonly, the low-e coating is an oxide material applied directly to the glass at high temperature. With over 100,000,000 existing homes, a retrofit product is crucial to achieve widespread energy savings. Low-e films, i.e. coatings on polymeric substrates, are now also available to meet this need. However, the traditional oxide materials and process is incompatible with low temperature plastics. Alternate high performing low-e films typically incorporate materials that limit visible transmission to 35% or less. Further, the cost is high. The objective of this award was to develop a retrofit, integrated low-e/electrochromic window film to dramatically reduce energy lost through windows. While field testing of state-of-the-art electrochromic (EC) windows show the energy savings are maximized if a low-e coating is used in conjunction with the EC, available low-e films have a low visible transmission (~70% or less) that limits the achievable clear state and therefore, appearance and energy savings potential. Comprehensive energy savings models were completed at Lawrence Berkeley National Lab (LBNL). A parametric approach was used to project energy usage for windows with a large range of low-e properties across all U.S. climate zones, without limiting the study to materials that had already been produced commercially or made in a lab. The model enables projection of energy savings for low-e films as well as integrated low-e/EC products. This project developed a novel low-e film, optimized for compatibility with EC windows, using low temperature, high deposition rate processes for the growth of low-e coatings on plastic films by microwave plasma enhanced chemical vapor deposition. Silica films with good density and optical properties were demonstrated at deposition rates as high as 130Å/sec. A simple bi-layer low-e stack of

  16. Requirements for supercomputing in energy research: The transition to massively parallel computing

    SciTech Connect

    Not Available

    1993-02-01

    This report discusses: The emergence of a practical path to TeraFlop computing and beyond; requirements of energy research programs at DOE; implementation: supercomputer production computing environment on massively parallel computers; and implementation: user transition to massively parallel computing.

  17. Controllable release from high-transition temperature magnetoliposomes by low-level magnetic stimulation.

    PubMed

    Spera, Romina; Apollonio, Francesca; Liberti, Micaela; Paffi, Alessandra; Merla, Caterina; Pinto, Rosanna; Petralito, Stefania

    2015-07-01

    High-transition temperature liposomes with embedded coated magnetite nanoparticles were prepared using the thin lipid film hydration method in order to obtain magnetoliposomes not sensitive to temperature increase (at least up to 50°C). Accordingly, drug can be released from such magnetoliposomes using a low-level electromagnetic field as triggering agent, while no delivery would be obtained with temperature increase within the physiological acceptable range. The hypothesized release mechanism involves mechanical stress of the liposome membrane due to nanoparticles oscillations and it is investigated by means of a numerical model evaluated using multiphysics simulations. The carrier content was repetitively released by switching on and off a 20kHz, 60A/m magnetic field. The results indicated high reproducibility of cycle-to-cycle release induced by the magnetic-impelled motions driving to the destabilization of the bilayer rather than the liposome phase transition or the destruction of the liposome structure.

  18. Controllable release from high-transition temperature magnetoliposomes by low-level magnetic stimulation.

    PubMed

    Spera, Romina; Apollonio, Francesca; Liberti, Micaela; Paffi, Alessandra; Merla, Caterina; Pinto, Rosanna; Petralito, Stefania

    2015-07-01

    High-transition temperature liposomes with embedded coated magnetite nanoparticles were prepared using the thin lipid film hydration method in order to obtain magnetoliposomes not sensitive to temperature increase (at least up to 50°C). Accordingly, drug can be released from such magnetoliposomes using a low-level electromagnetic field as triggering agent, while no delivery would be obtained with temperature increase within the physiological acceptable range. The hypothesized release mechanism involves mechanical stress of the liposome membrane due to nanoparticles oscillations and it is investigated by means of a numerical model evaluated using multiphysics simulations. The carrier content was repetitively released by switching on and off a 20kHz, 60A/m magnetic field. The results indicated high reproducibility of cycle-to-cycle release induced by the magnetic-impelled motions driving to the destabilization of the bilayer rather than the liposome phase transition or the destruction of the liposome structure. PMID:26042528

  19. The low-energy photon tagger NEPTUN

    NASA Astrophysics Data System (ADS)

    Savran, D.; Lindenberg, K.; Glorius, J.; Löher, B.; Müller, S.; Pietralla, N.; Schnorrenberger, L.; Simon, V.; Sonnabend, K.; Wälzlein, C.; Elvers, M.; Endres, J.; Hasper, J.; Zilges, A.

    2010-02-01

    A new photon tagging spectrometer was built at the superconducting Darmstadt electron linear accelerator (S-DALINAC). The system is designed for tagging photons in an energy range from 6 to 20 MeV with the emphasis on best possible energy resolution and intensity. The absolute energy resolution of photons at 10 MeV is expected to be about 20 keV. With scintillating fibres as focal-plane detectors a maximum rate of tagged photons of 104 keV -1s -1 will be achieved. Detailed design studies including Monte Carlo simulations are presented, as well as results for the measured tagged photon energy profile of the system realized so far. This photon-tagging facility will allow to determine the photon absorption cross-sections as a function of excitation energy and to study the decay patterns of nuclear photo-excitations in great detail.

  20. Integral low-energy thermite igniter

    DOEpatents

    Gibson, Albert; Haws, Lowell D.; Mohler, Jonathan H.

    1984-08-14

    In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

  1. Integral low-energy thermite igniter

    DOEpatents

    Gibson, A.; Haws, L.D.; Mohler, J.H.

    1983-05-13

    In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

  2. Low temperature phase transition and crystal structure of CsMgPO{sub 4}

    SciTech Connect

    Orlova, Maria; Khainakov, Sergey; Michailov, Dmitriy; Perfler, Lukas; Langes, Christoph; Kahlenberg, Volker; Orlova, Albina

    2015-01-15

    CsMgPO{sub 4} doped with radioisotopes is a promising compound for usage as a radioactive medical source. However, a low temperature phase transition at temperatures close to ambient conditions (∼−40 °C) was observed. Information about such kind of structural changes is important in order to understand whether it can cause any problem for medical use of this compound. The phase transition has been investigated in detail using synchrotron powder diffraction, Raman spectroscopy and DFT calculations. The structure undergoes a transformation from an orthorhombic modification, space group Pnma (RT phase) to a monoclinic polymorph, space group P2{sub 1}/n (LT phase). New LT modification adopts similar to RT but slightly distorted unit cell: a=9.58199(2) Å, b=8.95501(1) Å, c=5.50344(2) Å, β=90.68583(1)°, V=472.198(3) Å{sup 3}. CsMgPO{sub 4} belongs to the group of framework compounds and is made up of strictly alternating MgO{sub 4}- and PO{sub 4}-tetrahedra sharing vertices. The cesium counter cations are located in the resulting channel-like cavities. Upon the transformation a combined tilting of the tetrahedra is observed. A comparison with other phase transitions in ABW-type framework compounds is given. - Graphical abstract: Structural behavior of β-tridymite-type phosphate CsMgPO{sub 4}, considered as potential chemical form for radioactive Cs-source has been studied at near ambient temperatures. A phase transition at (∼−40 °C) has been found and investigated. It has been established that the known orthorhombic RT modification, space group Pnma, adopts a monoclinic cell with space group P2{sub 1}/n at low temperatures. In this paper, we present results of structural analysis of changes accompanying this phase transition and discuss its possible impact on the application properties. - Highlights: • β-Tridymite type phosphate CsMgPO{sub 4} undergoes so called translationengleiche phase transition of index 2 at −40 °C. • The structure

  3. Early-Morning Flow Transition in a Valley in Low-Mountain Terrain Under Clear-Sky Conditions

    NASA Astrophysics Data System (ADS)

    Brötz, Björn; Eigenmann, Rafael; Dörnbrack, Andreas; Foken, Thomas; Wirth, Volkmar

    2014-07-01

    We investigate the evolution of the early-morning boundary layer in a low-mountain valley in south-western Germany during COPS (convective and orographically induced precipitation study) in summer 2007. The term low-mountain refers to a mountainous region with a relief of gentle slopes and with an absolute altitude that remains under a specified height (usually 1,500 m a.s.l.). A subset of 23 fair weather days from the campaign was selected to study the transition of the boundary-layer flow in the early morning. The typical valley atmosphere in the morning hours was characterized by a stable temperature stratification and a pronounced valley wind system. During the reversal period—called the low wind period—of the valley wind system (duration of 1-2 h), the horizontal flow was very weak and the conditions for free convection were fulfilled close to the ground. Ground-based sodar observations of the vertical wind show enhanced values of upward motion, and the corresponding statistical properties differ from those observed under windless convective conditions over flat terrain. Large-eddy simulations of the boundary-layer transition in the valley were conducted, and statistical properties of the simulated flow agree with the observed quantities. Spatially coherent turbulence structures are present in the temporal as well as in the ensemble mean analysis. Thus, the complex orography induces coherent convective structures at predictable, specific locations during the early-morning low wind situations. These coherent updrafts, found in both the sodar observations and the simulation, lead to a flux counter to the gradient of the stably stratified valley atmosphere and reach up to the heights of the surrounding ridges. Furthermore, the energy balance in the surface layer during the low wind periods is closed. However, it becomes unclosed after the onset of the valley wind. The partition into the sensible and the latent heat fluxes indicates that missing flux

  4. Fuel Cell Transit Bus Evaluations: Joint Evaluation Plan for the U.S. Department of Energy and the Federal Transit Administration (Report and Appendix)

    SciTech Connect

    Eudy, L.; Chandler, K.

    2010-11-01

    This document describes the fuel cell transit bus evaluations performed by the National Renewable Energy Laboratory (NREL) and funded by the U.S. Department of Energy (DOE) and the U.S. Department of Transportation's Federal Transit Administration (FTA). This document provides a description of the demonstration sites, funding sources, and data collection activities for fuel cell transit bus evaluations currently planned from FY10 through FY12.

  5. Arizona's energy future: making the transition to a new mix

    SciTech Connect

    Not Available

    1981-10-01

    This report looks at Arizona's energy future in light of knowledge gained since 1976. It emphasizes conservation, cogeneration, solar, geothermal, and biomass energy promise. An interdisciplinary approach is used. (PSB)

  6. Review of lattice results concerning low-energy particle physics

    DOE PAGES

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; et al

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination ofmore » the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.« less

  7. Review of lattice results concerning low-energy particle physics

    SciTech Connect

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; Jüttner, A.; Kaneko, T.; Laiho, J.; Lellouch, L.; Leutwyler, H.; Lubicz, V.; Lunghi, E.; Necco, S.; Onogi, T.; Pena, C.; Sachrajda, C. T.; Sharpe, S. R.; Simula, S.; Sommer, R.; Van de Water, R. S.; Vladikas, A.; Wenger, U.; Wittig, H.

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination of the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.

  8. Oscillation of Very Low Energy Atmospheric Neutrinos

    SciTech Connect

    Peres, Orlando L. G.

    2010-03-30

    We discuss the oscillation effects of sub-sub-GeV atmospheric neutrinos, the sample with energies E < or approx. 100 MeV. The energy spectra of the e-like events in water Cherenkov detectors are computed and dependence of the spectra on the 2-3 mixing angle, theta{sub 23}, the 1-3 mixing and CP-violation phase are studied.

  9. Separated shear layer transition over an airfoil at a low Reynolds number

    NASA Astrophysics Data System (ADS)

    Boutilier, Michael S. H.; Yarusevych, Serhiy

    2012-08-01

    Shear layer development over a NACA 0018 airfoil at a chord Reynolds number of 100 000 was investigated using a combination of flow visualization, velocity field mapping, surface pressure fluctuation measurements, and stability analysis. The results provide a detailed description of shear layer transition on an airfoil at low Reynolds numbers. An extensive comparison of measured surface pressure and velocity fluctuations demonstrated that time-resolved surface pressure sensor arrays can be used to identify the presence of flow separation, estimate the extent of the separated flow region, and measure disturbance growth rate spectra in significantly less time than is required by conventional techniques. Surface pressure sensor measurements of disturbance growth rate, wave number, and convection speed are found to compare well with predictions of linear stability theory, supporting the claim that convection speeds measured in separation bubbles over low Reynolds number airfoils are associated with wave packets of growing disturbances propagating through the shear layer. Through a comparison of measured convection speeds in this investigation and prior low Reynolds number airfoil experiments, it is shown that disturbance convection speeds of between 30% and 50% of the edge velocity are typical for this type of flow, consistent with phase speed estimates from previous analytical studies on transitional separation bubbles. Modal RMS velocity profiles were measured and found to be reasonably predicted by stability theory. The results suggest that, even for the relatively thick NACA 0018 airfoil profile, disturbance development over the majority of the laminar separated shear layer is primarily governed by a linear inviscid mechanism.

  10. Scaling Relationships for Adsorption Energies of C2 Hydrocarbons on Transition Metal Surfaces

    SciTech Connect

    Jones, G

    2011-08-18

    Using density functional theory calculations we show that the adsorption energies for C{sub 2}H{sub x}-type adsorbates on transition metal surfaces scale with each other according to a simple bond order conservation model. This observation generalizes some recently recognized adsorption energy scaling laws for AH{sub x}-type adsorbates to unsaturated hydrocarbons and establishes a coherent simplified description of saturated as well as unsaturated hydrocarbons adsorbed on transition metal surfaces. A number of potential applications are discussed. We apply the model to the dehydrogenation of ethane over pure transition metal catalysts. Comparison with the corresponding full density functional theory calculations shows excellent agreement.

  11. Analytical expressions for partial wave two-body Coulomb transition matrices at ground-state energy

    NASA Astrophysics Data System (ADS)

    Kharchenko, V. F.

    2016-11-01

    Leaning upon the Fock method of the stereographic projection of the three-dimensional momentum space onto the four-dimensional unit sphere the possibility of the analytical solving of the Lippmann-Schwinger integral equation for the partial wave two-body Coulomb transition matrix at the ground bound state energy has been studied. In this case new expressions for the partial p-, d- and f-wave two-body Coulomb transition matrices have been obtained in the simple analytical form. The developed approach can also be extended to determine analytically the partial wave Coulomb transition matrices at the energies of excited bound states.

  12. Potential energy curves and electronic structure of 3d transition metal hydrides and their cations

    NASA Astrophysics Data System (ADS)

    Goel, Satyender; Masunov, Artëm E.

    2008-12-01

    We investigate gas-phase neutral and cationic hydrides formed by 3d transition metals from Sc to Cu with density functional theory (DFT) methods. The performance of two exchange-correlation functionals, Boese-Martin for kinetics (BMK) and Tao-Perdew-Staroverov-Scuseria (TPSS), in predicting bond lengths and energetics, electronic structures, dipole moments, and ionization potentials is evaluated in comparison with available experimental data. To ensure a unique self-consistent field (SCF) solution, we use stability analysis, Fermi smearing, and continuity analysis of the potential energy curves. Broken-symmetry approach was adapted in order to get the qualitatively correct description of the bond dissociation. We found that on average BMK predicted values of dissociation energies and ionization potentials are closer to experiment than those obtained with high level wave function theory methods. This agreement deteriorates quickly when the fraction of the Hartree-Fock exchange in DFT functional is decreased. Natural bond orbital (NBO) population analysis was used to describe the details of chemical bonding in the systems studied. The multireference character in the wave function description of the hydrides is reproduced in broken-symmetry DFT description, as evidenced by NBO analysis. We also propose a new scheme to correct for spin contamination arising in broken-symmetry DFT approach. Unlike conventional schemes, our spin correction is introduced for each spin-polarized electron pair individually and therefore is expected to yield more accurate energy values. We derive an expression to extract the energy of the pure singlet state from the energy of the broken-symmetry DFT description of the low spin state and the energies of the high spin states (pentuplet and two spin-contaminated triplets in the case of two spin-polarized electron pairs). The high spin states are build with canonical natural orbitals and do not require SCF convergence.

  13. Summary of low-energy aspects of QCD and medium-energy hadron parallel sessions

    SciTech Connect

    McClelland, J.B.

    1991-01-01

    Two sessions were organized dealing with low energy aspects of QCD. The first dealt with the issue of QCD dibaryons. The second session centered on mostly low-energy tests of QCD. This report discusses experiments dealing with these sessions.

  14. U.S. Energy Demand: Some Low Energy Futures

    ERIC Educational Resources Information Center

    Science, 1978

    1978-01-01

    Described is a study in which energy demands were analyzed and several plausable future energy scenarios were developed. The article attempts to illustrate the dynamics of energy demand and supply in the United States in order to aid future planning. (MDR)

  15. A Compact Low-loss Magic-T using Microstrip-Slotline Transitions

    NASA Technical Reports Server (NTRS)

    U-yen, Kongpop; Wollack, Edward J.; Moseley, Samuel H.; Papapolymerou, John; Laskar, Joy

    2007-01-01

    The design of a compact low-loss magic-T is proposed. The planar magic-T incorporates the compact microstrip-slotline tee junction and small microstrip-slotline transition area to reduce slotline radiation. The experimental results show that the magic-T produces broadband in-phase and out-of-phase power combiner/divider responses, has an average in-band insertion loss of 0.3 dB and small in-band phase and amplitude imbalance of less than plus or minus 1.6 deg. and plus or minus 0.3 dB, respectively.

  16. Calculations of energy levels and lifetimes of low-lying states of barium and radium

    SciTech Connect

    Dzuba, V. A.; Ginges, J. S. M.

    2006-03-15

    We use the configuration-interaction method and many-body perturbation theory to perform accurate calculations of energy levels, transition amplitudes, and lifetimes of low-lying states of barium and radium. Calculations for radium are needed for the planning of measurements of parity- and time-invariance-violating effects which are strongly enhanced in this atom. Calculations for barium are used to control the accuracy of the calculations.

  17. Low-Temperature and High-Energy-Resolution Laser Photoemission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Shimojima, Takahiro; Okazaki, Kozo; Shin, Shik

    2015-07-01

    We present a review on the developments in the photoemission spectrometer with a vacuum ultraviolet laser at Institute for Solid State Physics at the University of Tokyo. The advantages of high energy resolution, high cooling ability, and bulk sensitivity enable applications with a wide range of materials. We introduce some examples of fine electronic structures detected by laser photoemission spectroscopy and discuss the prospects of research on low-transition-temperature superconductors exhibiting unconventional superconductivity.

  18. Low temperature phase transition and crystal structure of CsMgPO4

    NASA Astrophysics Data System (ADS)

    Orlova, Maria; Khainakov, Sergey; Michailov, Dmitriy; Perfler, Lukas; Langes, Christoph; Kahlenberg, Volker; Orlova, Albina

    2015-01-01

    CsMgPO4 doped with radioisotopes is a promising compound for usage as a radioactive medical source. However, a low temperature phase transition at temperatures close to ambient conditions (~-40 °C) was observed. Information about such kind of structural changes is important in order to understand whether it can cause any problem for medical use of this compound. The phase transition has been investigated in detail using synchrotron powder diffraction, Raman spectroscopy and DFT calculations. The structure undergoes a transformation from an orthorhombic modification, space group Pnma (RT phase) to a monoclinic polymorph, space group P21/n (LT phase). New LT modification adopts similar to RT but slightly distorted unit cell: a=9.58199(2) Å, b=8.95501(1) Å, c=5.50344(2) Å, β=90.68583(1)°, V=472.198(3) Å3. CsMgPO4 belongs to the group of framework compounds and is made up of strictly alternating MgO4- and PO4-tetrahedra sharing vertices. The cesium counter cations are located in the resulting channel-like cavities. Upon the transformation a combined tilting of the tetrahedra is observed. A comparison with other phase transitions in ABW-type framework compounds is given.

  19. Activation energy for a model ferrous-ferric half reaction from transition path sampling.

    PubMed

    Drechsel-Grau, Christof; Sprik, Michiel

    2012-01-21

    Activation parameters for the model oxidation half reaction of the classical aqueous ferrous ion are compared for different molecular simulation techniques. In particular, activation free energies are obtained from umbrella integration and Marcus theory based thermodynamic integration, which rely on the diabatic gap as the reaction coordinate. The latter method also assumes linear response, and both methods obtain the activation entropy and the activation energy from the temperature dependence of the activation free energy. In contrast, transition path sampling does not require knowledge of the reaction coordinate and directly yields the activation energy [C. Dellago and P. G. Bolhuis, Mol. Simul. 30, 795 (2004)]. Benchmark activation energies from transition path sampling agree within statistical uncertainty with activation energies obtained from standard techniques requiring knowledge of the reaction coordinate. In addition, it is found that the activation energy for this model system is significantly smaller than the activation free energy for the Marcus model, approximately half the value, implying an equally large entropy contribution.

  20. The Role of Grain Boundary Energy on Grain Boundary Complexion Transitions

    SciTech Connect

    Bojarski, Stephanie A.; Rohrer, Gregory S.

    2014-09-01

    Grain boundary complexions are distinct equilibrium structures and compositions of a grain boundary and complexion transformations are transition from a metastable to an equilibrium complexion at a specific thermodynamic and geometric conditions. Previous work indicates that, in the case of doped alumina, a complexion transition that increased the mobility of transformed boundaries and resulted in abnormal grain growth also caused a decrease in the mean relative grain boundary energy as well as an increase in the anisotropy of the grain boundary character distribution (GBCD). The current work will investigate the hypothesis that the rates of complexion transitions that result in abnormal grain growth (AGG) depend on grain boundary character and energy. Furthermore, the current work expands upon this understanding and tests the hypothesis that it is possible to control when and where a complexion transition occurs by controlling the local grain boundary energy distribution.

  1. Treatment of Electronic Energy Level Transition and Ionization Following the Particle-Based Chemistry Model

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Lewis, Mark

    2010-01-01

    A new method of treating electronic energy level transitions as well as linking ionization to electronic energy levels is proposed following the particle-based chemistry model of Bird. Although the use of electronic energy levels and ionization reactions in DSMC are not new ideas, the current method of selecting what level to transition to, how to reproduce transition rates, and the linking of the electronic energy levels to ionization are, to the author s knowledge, novel concepts. The resulting equilibrium temperatures are shown to remain constant, and the electronic energy level distributions are shown to reproduce the Boltzmann distribution. The electronic energy level transition rates and ionization rates due to electron impacts are shown to reproduce theoretical and measured rates. The rates due to heavy particle impacts, while not as favorable as the electron impact rates, compare favorably to values from the literature. Thus, these new extensions to the particle-based chemistry model of Bird provide an accurate method for predicting electronic energy level transition and ionization rates in gases.

  2. Energy Transition Initiative: Island Energy Snapshot - Puerto Rico (Fact Sheet); NREL(National Renewable Energy Laboratory)

    SciTech Connect

    2015-03-01

    This profile provides a snapshot of the energy landscape of the Commonwealth of Puerto Rico - a U.S. territory located about 60 miles east of the Dominican Republic and directly west of the U.S. Virgin Islands.

  3. Low-energy positron interactions with krypton

    SciTech Connect

    Makochekanwa, C.; Machacek, J. R.; Jones, A. C. L.; Caradonna, P.; Slaughter, D. S.; McEachran, R. P.; Sullivan, J. P.; Buckman, S. J.; Bellm, S.; Lohmann, B.; Fursa, D. V.; Bray, I.; Mueller, D.W.; Stauffer, A. D.; Hoshino, M.

    2011-03-15

    Cross sections for positron scattering from krypton have been measured with an energy resolution of {approx}60 meV over the energy range 0.5-60 eV. Absolute values of the grand total ({sigma}{sub GT}), positronium formation ({sigma}{sub Ps}), and grand total minus positronium formation ({sigma}{sub GT}-{sigma}{sub Ps},) cross sections are presented. Theoretical estimations of {sigma}{sub GT} and {sigma}{sub GT}-{sigma}{sub Ps} are also performed for this target using the convergent close-coupling method and the relativistic optical potential approach. We also provide experimental and theoretical results for elastic differential cross sections, for selected energies both below and above the Ps threshold. Where available, the present results are compared to both experimental and theoretical values from the literature.

  4. Low energy center pivot sprinkler irrigation system

    SciTech Connect

    Gilley, J.R.

    1981-04-30

    Reducing the pressure of center-pivot irrigation systems can save energy; however, there can be management problems such as increased runoff and soil erosion and nonuniformity of water application. Options available to help overcome some of these problems are system capacity design, speed of rotation, application rate patterns, and modified cultural practices. Constraints on the use of reduced-pressure center-pivots will often be site specific and depend on the soil type, topography, crop, and history of land use. Reductions in irrigation efficiency resulting from reduced pressure must be considered when determining the net energy savings from reduced-pressure systems. Reduction in irrigation efficiency may negate the energy saved by pressure reduction, especially for those systems with larger lifts.

  5. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes

    NASA Astrophysics Data System (ADS)

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng

    2013-11-01

    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O2 adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N4 chelation, as well as the molecular and electronic structures for the O2 adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O2 on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d_{z^2 }, d_{xy}, d_{xz}, and dyz) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O2 adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  6. Correlation between oxygen adsorption energy and electronic structure of transition metal macrocyclic complexes

    SciTech Connect

    Liu, Kexi; Lei, Yinkai; Wang, Guofeng

    2013-11-28

    Oxygen adsorption energy is directly relevant to the catalytic activity of electrocatalysts for oxygen reduction reaction (ORR). In this study, we established the correlation between the O{sub 2} adsorption energy and the electronic structure of transition metal macrocyclic complexes which exhibit activity for ORR. To this end, we have predicted the molecular and electronic structures of a series of transition metal macrocyclic complexes with planar N{sub 4} chelation, as well as the molecular and electronic structures for the O{sub 2} adsorption on these macrocyclic molecules, using the density functional theory calculation method. We found that the calculated adsorption energy of O{sub 2} on the transition metal macrocyclic complexes was linearly related to the average position (relative to the lowest unoccupied molecular orbital of the macrocyclic complexes) of the non-bonding d orbitals (d{sub z{sup 2}}, d{sub xy}, d{sub xz}, and d{sub yz}) which belong to the central transition metal atom. Importantly, our results suggest that varying the energy level of the non-bonding d orbitals through changing the central transition metal atom and/or peripheral ligand groups could be an effective way to tuning their O{sub 2} adsorption energy for enhancing the ORR activity of transition metal macrocyclic complex catalysts.

  7. Transition report, United States Department of Energy: A report to the President-Elect. Volume 2

    SciTech Connect

    Not Available

    1988-11-01

    This report is a description of the Department of Energy transition issues. The topics of the report include: Congressional, Intergovernmental and Public Affairs; Conservation and Renewable Energy; Defense Programs; New Production Reactors; Economic Regulatory Administration; Energy Information Administration; energy research; environment, safety and health; fossil energy; General Counsel; hearings and appeals, Inspector General, international affairs and energy emergencies; management and administration, minority economic impact; nuclear energy; policy, planning and analysis, radioactive waste management; and power marketing administrations: Bonneville Power Administration, Western Area Power Administration, Alaska Power Administration, Southeastern Power Administration, and Southwestern Power Administration.

  8. Feasibility of Electron Cooling for Low-Energy RHIC Operation

    SciTech Connect

    Fedotov,A.; Ben-Zvi, I.; Chang, X.; Kayran, D.; Litvinenko, V.; Pozdeyev, E.; Satogata, T.

    2008-04-01

    A concrete interest in running RHIC at low energies in a range of 2.5-25 GeV/nucleon total energy of a single beam has recently emerged. Providing collisions in this energy range, which in the RHIC case is termed 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of a critical point on the QCD phase diagram. However, luminosity projections are relatively low for the lowest energy points of interest. Luminosity improvement can be provided with electron cooling applied directly in RHIC at low energies. This report summarizes the expected luminosity improvement with electron cooling, possible technical approaches and various limitations.

  9. Energy in New England: Transition to the 80's

    NASA Astrophysics Data System (ADS)

    Katz, R.; Pawlick, L.; Spencer, B.

    1981-06-01

    Activities in New England which result in more efficient consumption of energy are discussed. Change in aggregate energy demand since the oil embargo, energy use and the regional economy, incentives for conservation, and decline in electricity growth are also discussed. The conributions made by wood products, hydroelectric power, solid waste, solar, wind, alcohol fuels, peat, and tidal power are disclosed. Changes in consumption of individual conventional energy products (petroleum, natural gas, nuclear power, coal, purchased electricity) and activity currently underway in the conventional fuel area are summarized.

  10. The effect of surface and interface on Neel transition temperature of low-dimensional antiferromagnetic materials

    SciTech Connect

    Zhang, Wen; Zhou, Zhaofeng Zhong, Yuan; Zhang, Ting; Huang, Yongli; Sun, Changqing

    2015-11-15

    Incorporating the bond order-length-strength (BOLS) notion with the Ising premise, we have modeled the size dependence of the Neel transition temperature (T{sub N}) of antiferromagnetic nanomaterials. Reproduction of the size trends reveals that surface atomic undercoordination induces bond contraction, and interfacial hetero-coordination induces bond nature alteration. Both surface and interface of nanomaterials modulate the T{sub N} by adjusting the atomic cohesive energy. The T{sub N} is related to the atomic cohesive/exchange energy that is lowered by the coordination number (CN) imperfection of the undercoordinated atoms near the surface and altered by the changed bond nature of epitaxial interface. A numerical match between predictions and measurements reveals that the T{sub N} of antiferromagnetic nanomaterials declines with reduced size and increases with both the strengthening of heterogeneous bond and the increase of the bond number.

  11. Eccentricity from Transit Photometry: Small Planets in Kepler Multi-planet Systems Have Low Eccentricities

    NASA Astrophysics Data System (ADS)

    Van Eylen, Vincent; Albrecht, Simon

    2015-08-01

    Solar system planets move on almost circular orbits. In strong contrast, many massive gas giant exoplanets travel on highly elliptical orbits, whereas the shape of the orbits of smaller, more terrestrial, exoplanets remained largely elusive. Knowing the eccentricity distribution in systems of small planets would be important as it holds information about the planet's formation and evolution, and influences its habitability. We make these measurements using photometry from the Kepler satellite and utilizing a method relying on Kepler's second law, which relates the duration of a planetary transit to its orbital eccentricity, if the stellar density is known. Our sample consists of 28 bright stars with precise asteroseismic density measurements. These stars host 74 planets with an average radius of 2.6 R⊕. We find that the eccentricity of planets in Kepler multi-planet systems is low and can be described by a Rayleigh distribution with σ = 0.049 ± 0.013. This is in full agreement with solar system eccentricities, but in contrast to the eccentricity distributions previously derived for exoplanets from radial velocity studies. Our findings are helpful in identifying which planets are habitable because the location of the habitable zone depends on eccentricity, and to determine occurrence rates inferred for these planets because planets on circular orbits are less likely to transit. For measuring eccentricity it is crucial to detect and remove Transit Timing Variations (TTVs), and we present some previously unreported TTVs. Finally transit durations help distinguish between false positives and true planets and we use our measurements to confirm six new exoplanets.

  12. Low-energy theory of disordered graphene.

    PubMed

    Altland, Alexander

    2006-12-01

    At low values of external doping, graphene displays a wealth of unconventional transport properties. Perhaps most strikingly, it supports a robust "metallic" regime, with universal conductance of the order of the conductance quantum. We here apply a combination of mean-field and bosonization methods to explore the large scale transport properties of the system. We find that, irrespective of the doping level, disordered graphene is subject to the common mechanisms of Anderson localization. However, at low doping a number of renormalization mechanisms conspire to protect the conductivity of the system, to an extend that strong localization may not be seen even at temperatures much smaller than those underlying present experimental work.

  13. Low-Tech Energy Conservation for Schools.

    ERIC Educational Resources Information Center

    Stein, Benjamin

    The American Institute of Architects National Committee on Architecture for Education presents this guide which addresses methods of energy conservation in school buildings with simple design, construction, and equipment-control technology so that trained and creative people can take over functions normally done by machinery and automated…

  14. Strong flux of low-energy neutrons produced by thunderstorms.

    PubMed

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed.

  15. Low-energy D+ and H+ ion irradiation effects on highly oriented pyrolytic graphite

    NASA Astrophysics Data System (ADS)

    Kue Park, Jun; Won Lee, Kyu; Hee Han, Jun; Jung Kweon, Jin; Kim, Dowan; Eui Lee, Cheol; Lim, Sun-Taek; Kim, Gon-Ho; Noh, S. J.; Kim, H. S.

    2013-12-01

    We have investigated the low-energy (100 eV) D+ and H+ ion irradiation effects on the structural and chemical properties of highly oriented pyrolytic graphite (HOPG). Structural disorder due to the ion irradiation was identified by the Raman spectroscopy, the D+ irradiation giving rise to greater structural disorder than the H+ irradiation. Only sp2 bonding was identified in the X-ray photoemission spectroscopy of the D+-irradiated HOPG, indicating no change in the surface chemical structure. The H+ irradiation, on the other hand, gave rise to sp3 bonding and π -π* transition, the sp3 bonding increasing with increasing irradiation dose. It is thus shown that the chemical properties of the HOPG surface may be sensitively modified by the low-energy H+ ion irradiation, but not by the low-energy D+ ion irradiation.

  16. Walkability, Transit Access, and Traffic Exposure for Low-Income Residents With Subsidized Housing

    PubMed Central

    Basolo, Victoria; Yang, Dongwoo

    2013-01-01

    Objectives. We assessed the spatial distribution of subsidized housing units provided through 2 federally supported, low-income housing programs in Orange County, California, in relation to neighborhood walkability, transit access, and traffic exposure. Methods. We used data from multiple sources to examine land-use and health-related built environment factors near housing subsidized through the Housing Choice Voucher Program and the Low Income Housing Tax Credit (LIHTC) program, and to determine these patterns’ associations with traffic exposure. Results. Subsidized projects or units in walkable, poorer neighborhoods were associated with lower traffic exposure; higher traffic exposure was associated with more transit service, a Hispanic majority, and mixed-use areas. Voucher units are more likely than LIHTC projects to be located in high-traffic areas. Conclusions. Housing program design may affect the location of subsidized units, resulting in differential traffic exposure for households by program type. Further research is needed to better understand the relationships among subsidized housing locations, characteristics of the built environment, and health concerns such as traffic exposure, as well as which populations are most affected by these relationships. PMID:22897555

  17. Low Energy, Low Emissions: Sulfur Dioxide; Nitrogen Oxides, and Carbon Dioxide in Western Europe.

    ERIC Educational Resources Information Center

    Alcamo, Joseph; De Vries, Bert

    1992-01-01

    Links proposed low-energy scenarios for different Western European countries with the amount of pollutants that may result from these scenarios. Sulfur dioxide, nitrogen oxide, and carbon dioxide emissions are calculated for the 10 countries for which low-energy scenarios are available, resulting in reductions of 54%, 37%, and 40%, respectively.…

  18. Mass and Energy: The Low-Energy Limit.

    ERIC Educational Resources Information Center

    Bauman, Robert P.

    1994-01-01

    Discusses Einstein's equation relating mass and energy highlighting these questions: (1) Can mass and energy be converted into one another? (2) What is the origin of the equation? (3) How do relativistic mass and rest mass relate? and (4) How is relativistic mass used in resulting equations? (MVL)

  19. Measurements of low energy auroral ions

    NASA Astrophysics Data System (ADS)

    Urban, A.

    1981-12-01

    Ion measurements in the energy range 0.1-30 keV observed during the 'Substorm Phenomena' and 'Porcupine' campaigns are summarized. Acceleration of the ions by an electrostatic field aligned parallel to the magnetic field is identified and found to be accompanied by intense electron precipitation. On the other hand, deceleration of the ions is observed in other field-aligned current sheets which are indicated by the electron and magnetic field measurements. Temporal successive monoenergetic ion variations suggest energy dispersion and a location of the source region at 9 earth radii. What is more, ion fluxes higher than those of the electrons are measured at pitch angles parallel to the magnetic field. It is noted that each of the examples was observed during different flights.

  20. Formation of low-energy antihydrogen

    SciTech Connect

    Holzscheiter, M.H.; ATHENA Collaboration

    1999-03-01

    Antihydrogen atoms, produced near rest, trapped in a magnetic well, and cooled to the lowest possible temperature (kinetic energy) could provide an extremely powerful tool for the search of violations of CPT and Lorentz invariance. The author describes plans to trap antiprotons and positrons in a combined Penning trap and to form a significant number of cold antihydrogen atoms for comparative precision spectroscopy of hydrogen and antihydrogen.

  1. Electric properties and phase transition behavior in lead lanthanum zirconate stannate titanate ceramics with low zirconate content

    NASA Astrophysics Data System (ADS)

    Zeng, Tao; Lou, Qi-Wei; Chen, Xue-Feng; Zhang, Hong-Ling; Dong, Xian-Lin; Wang, Gen-Shui

    2015-11-01

    The phase transitions, dielectric properties, and polarization versus electric field (P-E) hysteresis loops of Pb0.97La0.02(Zr0.42Sn0.58-xTix)O3 (0.13≤ x ≤0.18) (PLZST) bulk ceramics were systematically investigated. This study exhibited a sequence of phase transitions by analyzing the change of the P-E hysteresis loops with increasing temperature. The antiferroelectric (AFE) to ferroelectric (FE) phase boundary of PLZST with the Zr content of 0.42 was found to locate at the Ti content between 0.14 and 0.15. This work is aimed to improve the ternary phase diagram of lanthanum-doped PZST with the Zr content of 0.42 and will be a good reference for seeking high energy storage density in the PLZST system with low-Zr content. Project supported by the National Natural Science Foundation of China (Grant Nos. 51202273, 11204304, and 11304334) and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 14DZ2261000).

  2. Low energy neutron measurements aboard encounter missions

    NASA Astrophysics Data System (ADS)

    Vilmer, N.; Maksimovic, M.; Trottet, G.

    Neutrons in the MeV to GeV range are produced by interaction of flare accelerated ions with the solar atmosphere. Because of their lifetime, only high energy neutrons (> 100 MeV) have a high probability to be detected at earth's orbit. So far, around fifteen solar neutron events have been observed either by high energy detectors aboard spacecrafts at 1 AU or by ground based neutron monitors. Neutrons between 10 and 100 MeV have also been detected for a few events through their proton decay. Measurements of solar neutrons closer to the Sun aboard encounter missions will allow to probe for the first time the MeV neutrons which are produced by the nuclear reactions of energetic ions with thresholds around 1 MeV/nuc and will provide information on the accelerated ion spectrum in the energy range between ˜ 1 MeV and 100 MeV/nuc in complementarity with what can be deduced from γ -ray line emission. The close proximity of the Sun would allow to measure neutron events for many more flares opening a new field of solar physics. Combined with near in-situ ion measurements and γ -ray observations, neutrons will bring information on the link between interacting and escaping ions while getting rid of most of the transport effects.

  3. Low Energy Dissipation Nano Device Research

    NASA Astrophysics Data System (ADS)

    Yu, Jenny

    2015-03-01

    The development of research on energy dissipation has been rapid in energy efficient area. Nano-material power FET is operated as an RF power amplifier, the transport is ballistic, noise is limited and power dissipation is minimized. The goal is Green-save energy by developing the Graphene and carbon nantube microwave and high performance devices. Higher performing RF amplifiers can have multiple impacts on broadly field, for example communication equipment, (such as mobile phone and RADAR); higher power density and lower power dissipation will improve spectral efficiency which translates into higher system level bandwidth and capacity for communications equipment. Thus, fundamental studies of power handling capabilities of new RF (nano)technologies can have broad, sweeping impact. Because it is critical to maximizing the power handling ability of grephene and carbon nanotube FET, the initial task focuses on measuring and understanding the mechanism of electrical breakdown. We aim specifically to determine how the breakdown voltage in graphene and nanotubes is related to the source-drain spacing, electrode material and thickness, and substrate, and thus develop reliable statistics on the breakdown mechanism and probability.

  4. Abnormal heating of low-energy electrons in low-pressure capacitively coupled discharges.

    PubMed

    Park, G Y; You, S J; Iza, F; Lee, J K

    2007-02-23

    In low-pressure capacitively coupled plasmas, high-energy electrons are collisionlessly heated by large rf fields in the sheaths while low-energy electrons are confined in the bulk plasma by the ambipolar potential. Low-energy electrons are typically inefficiently heated due to their low collisionality and the weak rf electric field present in the bulk. It is shown, however, that as a result of the nonlinear interaction between the electron motion and the weak rf field present in the bulk, low-energy electrons can be efficiently heated. Electrons in the bulk that bounce inside the electrostatic potential well with a frequency equal to the rf excitation frequency are efficiently heated by the coherent interaction with the rf field. This resonant collisionless heating can be very efficient and manifest itself as a plateau in the electron energy probability function.

  5. Energy Independence for North America - Transition to the Hydrogen Economy

    SciTech Connect

    Eberhardt, J.

    2003-08-24

    The U.S. transportation sector is almost totally dependent on liquid hydrocarbon fuels, primarily gasoline and diesel fuel from conventional oil. In 2002, the transportation sector accounted for 69 percent of the U.S. oil use; highway vehicles accounted for 54 percent of the U.S. oil use. Of the total energy consumed in the U.S., more than 40 percent came from oil. More significantly, more than half of this oil is imported and is projected by the Energy Information Agency (EIA) to increase to 68 percent by 2025 [1]. The supply and price of oil have been dictated by the Organization of Petroleum Exporting Countries (OPEC). In 2002, OPEC accounted for 39 percent of world oil production and this is projected by the EIA to increase to 50 percent in 2025. Of the world's oil reserves, about 80 percent is owned by OPEC members. Major oil price shocks have disrupted world energy markets four times in the past 30 years (1973-74, 1979-80, 1990-1991, and 1999- 2000) and with each came either a recession or slowdown in the GDP (Gross Domestic Product) of the United States. In addition, these market upheavals have cost the U.S. approximately $7 trillion (in 1998 dollars) in total economic costs [2]. Finally, it is estimated that military expenditures for defending oil supplies in the Middle East range from $6 billion to $60 billion per year [3] and do not take into account the costs of recent military operations in Iraq (i.e., Operation Iraqi Freedom, 2003). At the outset of his administration in 2001, President George W. Bush established the National Energy Policy Development (NEPD) Group to develop a national energy policy to promote dependable, affordable, and environmentally sound energy for the future in order to avert potential energy crises. In the National Energy Policy report [4], the NEPD Group urges action by the President to meet five specific national goals that America must meet--''modernize conservation, modernize our energy infrastructure, increase energy

  6. Energy Transition Initiative: Island Energy Snapshot - Trinidad and Tobago; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    2015-05-20

    This profile provides a snapshot of the energy landscape of Trinidad and Tobago, a two-island nation located off the coast of Venezuela. Trinidad and Tobago’s electricity rates are some of the lowest in the Caribbean at approximately $0.04 per kilowatt-hour (kWh), well below the regional average of $0.33/kWh.

  7. Energy Transition Initiative: Island Energy Snapshot - Antigua and Barbuda; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    2015-05-20

    This profile provides a snapshot of the energy landscape of Antigua and Barbuda, an independent nation in the Leeward Islands in the eastern Caribbean Sea. Antigua and Barbuda’s utility rates are approximately $0.37 U.S. dollars (USD) per kilowatt-hour (kWh), which is above the Caribbean regional average of $0.33 USD/kWh.

  8. Energy Transition Initiative: Island Energy Snapshot - Guadeloupe; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    2015-05-27

    This profile provides a snapshot of the energy landscape of Guadeloupe, an overseas region of France located in the eastern Caribbean Sea. Guadeloupe’s utility rates are approximately $0.18 U.S. dollars (USD) per kilowatt-hour (kWh), below the Caribbean regional average of $0.33 USD/kWh.

  9. Influence of manufacturing factors on physical stability and solubility of solid dispersions containing a low glass transition temperature drug.

    PubMed

    Sakurai, Atsushi; Sako, Kazuhiro; Maitani, Yoshie

    2012-01-01

    In this study, we investigated the effect of manufacturing factors such as particle size, water content and manufacturing method on the physical stability and solubility of solid dispersion formulations of a low-glass-transition-temperature (T(g)) drug. Solid dispersions were prepared from polyvinylpyrrolidone (PVP) and hydroxypropylmethylcellulose (HPMC) by hot melt extrusion or spray drying. Water content of solid dispersions prepared by hot melt extrusion determined by dynamic moisture sorption measurement was increased drastically with relative humidity below a certain level of particle size. The blends with a lower water content (0.8%) prepared by hot melt extrusion during storage were more stable than those with a higher water content (3.5%) prepared by spray drying, which caused rapid recrystallization. Physical stability in the hot melt blends may be attributed to reduced molecular mobility due to a higher T(g). Dissolution study revealed that solid dispersions prepared by hot melt extrusion with the smallest particle size showed decreased solubility, attributed to reduced wetting properties (surface energy), which is not predictable by the Noyes-Whitney equation. Taken together, these results indicate that the control of particle size concerned in water content or wetting properties is critical to ensuring the physical stability or enhancing solubility of low-T(g) drugs. Further, hot melt extrusion, which can reduce water content, is a suitable manufacturing method for solid dispersions of low-T(g) drugs. PMID:23124559

  10. Influence of manufacturing factors on physical stability and solubility of solid dispersions containing a low glass transition temperature drug.

    PubMed

    Sakurai, Atsushi; Sako, Kazuhiro; Maitani, Yoshie

    2012-01-01

    In this study, we investigated the effect of manufacturing factors such as particle size, water content and manufacturing method on the physical stability and solubility of solid dispersion formulations of a low-glass-transition-temperature (T(g)) drug. Solid dispersions were prepared from polyvinylpyrrolidone (PVP) and hydroxypropylmethylcellulose (HPMC) by hot melt extrusion or spray drying. Water content of solid dispersions prepared by hot melt extrusion determined by dynamic moisture sorption measurement was increased drastically with relative humidity below a certain level of particle size. The blends with a lower water content (0.8%) prepared by hot melt extrusion during storage were more stable than those with a higher water content (3.5%) prepared by spray drying, which caused rapid recrystallization. Physical stability in the hot melt blends may be attributed to reduced molecular mobility due to a higher T(g). Dissolution study revealed that solid dispersions prepared by hot melt extrusion with the smallest particle size showed decreased solubility, attributed to reduced wetting properties (surface energy), which is not predictable by the Noyes-Whitney equation. Taken together, these results indicate that the control of particle size concerned in water content or wetting properties is critical to ensuring the physical stability or enhancing solubility of low-T(g) drugs. Further, hot melt extrusion, which can reduce water content, is a suitable manufacturing method for solid dispersions of low-T(g) drugs.

  11. EVOLUTION OF THE CRAB NEBULA IN A LOW ENERGY SUPERNOVA

    SciTech Connect

    Yang, Haifeng; Chevalier, Roger A. E-mail: rac5x@virginia.edu

    2015-06-20

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼10{sup 50} erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

  12. Past, present and future low energy antiproton facilities at CERN

    NASA Astrophysics Data System (ADS)

    Bartmann, W.; Belochitskii, P.; Breuker, H.; Butin, F.; Carli, C.; Eriksson, T.; Maury, S.; Oelert, W.; Pasinelli, S.; Tranquille, G.

    2014-05-01

    Low energy antiprotons are available for physics experiments at CERN since the 1980s and have been used by a large variety of experiments. The Low Energy Antiproton Ring LEAR has been constructed as a complementary use of antiprotons available at that time for high energy physics and delivered beam to experiments mainly using slow extraction. After completion of LEAR exploitation, the Antiproton Decelerator (AD) was constructed (adaptation of the existing Antiproton Collector, AC) to allow for a simpler low energy antiproton scheme (only one accelerator operated with Antiprotons) with fast extraction well suited for trap experiments. The Extra Low ENergy Antiproton ring ELENA is a small synchrotron presently constructed to further decelerate antiprotons from the AD in a controlled manner, and to reduce emittances with the help of an electron cooler to improve the capture efficiencies of existing experiments and allow for additional ones.

  13. Evolution of the Crab Nebula in a Low Energy Supernova

    NASA Astrophysics Data System (ADS)

    Yang, Haifeng; Chevalier, Roger A.

    2015-06-01

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼1050 erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

  14. Low protein diets produce divergent effects on energy balance

    PubMed Central

    Pezeshki, Adel; Zapata, Rizaldy C.; Singh, Arashdeep; Yee, Nicholas J.; Chelikani, Prasanth K.

    2016-01-01

    Diets deficient in protein often increase food consumption, body weight and fat mass; however, the underlying mechanisms remain poorly understood. We compared the effects of diets varying in protein concentrations on energy balance in obesity-prone rats. We demonstrate that protein-free (0% protein calories) diets decreased energy intake and increased energy expenditure, very low protein (5% protein) diets increased energy intake and expenditure, whereas moderately low protein (10% protein) diets increased energy intake without altering expenditure, relative to control diet (15% protein). These diet-induced alterations in energy expenditure are in part mediated through enhanced serotonergic and β-adrenergic signaling coupled with upregulation of key thermogenic markers in brown fat and skeletal muscle. The protein-free and very low protein diets decreased plasma concentrations of multiple essential amino acids, anorexigenic and metabolic hormones, but these diets increased the tissue expression and plasma concentrations of fibroblast growth factor-21. Protein-free and very low protein diets induced fatty liver, reduced energy digestibility, and decreased lean mass and body weight that persisted beyond the restriction period. In contrast, moderately low protein diets promoted gain in body weight and adiposity following the period of protein restriction. Together, our findings demonstrate that low protein diets produce divergent effects on energy balance. PMID:27122299

  15. Low Energy Nuclear Reaction Products at Surfaces

    NASA Astrophysics Data System (ADS)

    Nagel, David J.

    2008-03-01

    This paper examines the evidence for LENR occurring on or very near to the surface of materials. Several types of experimental indications for LENR surface reactions have been reported and will be reviewed. LENR result in two types of products, energy and the appearance of new elements. The level of instantaneous power production can be written as the product of four factors: (1) the total area of the surface on which the reactions can occur, (2) the fraction of the area that is active at any time, (3) the reaction rate, that is, the number of reactions per unit active area per second, and (4) the energy produced per reaction. Each of these factors, and their limits, are reviewed. A graphical means of relating these four factors over their wide variations has been devised. The instantaneous generation of atoms of new elements can also be written as the product of the first three factors and the new elemental mass produced per reaction. Again, a graphical means of presenting the factors and their results over many orders of magnitude has been developed.

  16. High energy, low frequency, ultrasonic transducer

    SciTech Connect

    Brown, Albert E.

    2000-01-01

    A wide bandwidth, ultrasonic transducer to generate nondispersive, extensional, pulsed acoustic pressure waves into concrete reinforced rods and tendons. The wave propagation distance is limited to double the length of the rod. The transducer acoustic impedance is matched to the rod impedance for maximum transfer of acoustic energy. The efficiency of the transducer is approximately 60 percent, depending upon the type of active elements used in the transducer. The transducer input energy is, for example, approximately 1 mJ. Ultrasonic reflections will occur at points along the rod where there are changes of one percent of a wavelength in the rod diameter. A reduction in the rod diameter will reflect a phase reversed echo, as compared with the reflection from an incremental increase in diameter. Echo signal processing of the stored waveform permits a reconstruction of those echoes into an image of the rod. The ultrasonic transducer has use in the acoustic inspection of long (40+foot) architectural reinforcements and structural supporting members, such as in bridges and dams.

  17. Institutions and the transition to adulthood: Implications for fertility tempo in low-fertility settings

    PubMed Central

    Brauner-Otto, Sarah R.

    2010-01-01

    The number of countries experiencing very low fertility has been rising in recent years, garnering increasing academic, political and media attention. There is now widespread academic agreement that the postponement of fertility is a major contributing factor in the very low levels of fertility that have occurred, and yet most policy discussions have been devoted to increasing the numbers of children women have. We discuss factors in three institutions—the educational system, the labour market and the housing market—that may inadvertently have led to childbearing postponement. We highlight important components of the timing of childbearing, including its changing place within the transition to adulthood across countries and the significance of the demands of childbearing versus childrearing. Using illustrations from Europe, North America, Japan, Australia and New Zealand, we argue that the following all lead to younger childbearing: 1) an open education system whereby it is relatively easy to return to school after having dropped out for a while; 2) a shorter, smoother, easier school-to-work transition; 3) easier re-entry into the labour market after having taken time out for childrearing or any other reason; 4) greater capability of integrating childrearing into a career; 5) easier ability to obtain a mortgage with a moderately small down payment, moderately low interest rate and a long time period over which to repay the loan; and 6) easier ability to rent a dwelling unit at an affordable price. Conversely, reversing any or all of these factors would lead, other things being equal, to postponement of childbearing. PMID:20622992

  18. Parity violation in low-energy neutron-deuteron scattering

    SciTech Connect

    Song, Young-Ho; Gudkov, Vladimir; Lazauskas, Rimantas

    2011-01-15

    Parity-violating effects for low-energy elastic neutron deuteron scattering are calculated for Desplanques, Donoghue, and Holstein (DDH) and effective field theory types of weak potentials in a distorted-wave Born approximation, using realistic hadronic strong interaction wave functions, obtained by solving three-body Faddeev equations in configuration space. The resulting relation between physical observables and low-energy constants can be used to fix low-energy constants from experiments. Potential model dependencies of parity-violating effects are discussed.

  19. Turbulence kinetic energy budget during the afternoon transition - Part 2: A simple TKE model

    NASA Astrophysics Data System (ADS)

    Nilsson, Erik; Lothon, Marie; Lohou, Fabienne; Pardyjak, Eric; Hartogensis, Oscar; Darbieu, Clara

    2016-07-01

    A simple model for turbulence kinetic energy (TKE) and the TKE budget is presented for sheared convective atmospheric conditions based on observations from the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) field campaign. It is based on an idealized mixed-layer approximation and a simplified near-surface TKE budget. In this model, the TKE is dependent on four budget terms (turbulent dissipation rate, buoyancy production, shear production and vertical transport of TKE) and only requires measurements of three available inputs (near-surface buoyancy flux, boundary layer depth and wind speed at one height in the surface layer) to predict vertical profiles of TKE and TKE budget terms.This simple model is shown to reproduce some of the observed variations between the different studied days in terms of near-surface TKE and its decay during the afternoon transition reasonably well. It is subsequently used to systematically study the effects of buoyancy and shear on TKE evolution using idealized constant and time-varying winds during the afternoon transition. From this, we conclude that many different TKE decay rates are possible under time-varying winds and that generalizing the decay with simple scaling laws for near-surface TKE of the form tα may be questionable.The model's errors result from the exclusion of processes such as elevated shear production and horizontal advection. The model also produces an overly rapid decay of shear production with height. However, the most influential budget terms governing near-surface TKE in the observed sheared convective boundary layers are included, while only second-order factors are neglected. Comparison between modeled and averaged observed estimates of dissipation rate illustrates that the overall behavior of the model is often quite reasonable. Therefore, we use the model to discuss the low-turbulence conditions that form first in the upper parts of the boundary layer during the afternoon transition and are only

  20. Evidence for the dipole nature of the low-energy γ enhancement in Fe56

    DOE PAGES

    Larsen, A. C.; Blasi, N.; Bracco, A.; Camera, F.; Eriksen, T. K.; Gorgen, A.; Guttormsen, M.; Hagen, T. W.; Leoni, S.; Million, B.; et al

    2013-12-11

    Here, the γ-ray strength function of 56Fe has been measured from proton-γ coincidences for excitation energies up to ≈11 MeV. The low-energy enhancement in the γ-ray strength function, which was first discovered in the (3He,αγ)56Fe reaction, is confirmed with the (p,p'γ)56Fe experiment reported here. Angular distributions of the γ rays give for the first time evidence that the enhancement is dominated by dipole transitions.

  1. Evidence for the dipole nature of the low-energy γ enhancement in 56Fe.

    PubMed

    Larsen, A C; Blasi, N; Bracco, A; Camera, F; Eriksen, T K; Görgen, A; Guttormsen, M; Hagen, T W; Leoni, S; Million, B; Nyhus, H T; Renstrøm, T; Rose, S J; Ruud, I E; Siem, S; Tornyi, T; Tveten, G M; Voinov, A V; Wiedeking, M

    2013-12-13

    The γ-ray strength function of 56Fe has been measured from proton-γ coincidences for excitation energies up to ≈11  MeV. The low-energy enhancement in the γ-ray strength function, which was first discovered in the (3He,αγ)56Fe reaction, is confirmed with the (p,p'γ)56Fe experiment reported here. Angular distributions of the γ rays give for the first time evidence that the enhancement is dominated by dipole transitions.

  2. Large low-energy M1 strength for ^{56,57}Fe within the nuclear shell model.

    PubMed

    Brown, B Alex; Larsen, A C

    2014-12-19

    A strong enhancement at low γ-ray energies has recently been discovered in the γ-ray strength function of ^{56,57}Fe. In this work, we have for the first time obtained theoretical γ decay spectra for states up to ≈8  MeV in excitation for ^{56,57}Fe. We find large B(M1) values for low γ-ray energies that provide an explanation for the experimental observations. The role of mixed E2 transitions for the low-energy enhancement is addressed theoretically for the first time, and it is found that they contribute a rather small fraction. Our calculations clearly show that the high-ℓ(=f) diagonal terms are most important for the strong low-energy M1 transitions. As such types of 0ℏω transitions are expected for all nuclei, our results indicate that a low-energy M1 enhancement should be present throughout the nuclear chart. This could have far-reaching consequences for our understanding of the M1 strength function at high excitation energies, with profound implications for astrophysical reaction rates.

  3. Low Energy Accelerators for Cargo Inspection

    NASA Astrophysics Data System (ADS)

    Tang, Chuanxiang

    Cargo inspection by X-rays has become essential for seaports and airports. With the emphasis on homeland security issues, the identification of dangerous things, such as explosive items and nuclear materials, is the key feature of a cargo inspection system. And new technologies based on dual energy X-rays, neutrons and monoenergetic X-rays have been studied to achieve sufficiently good material identification. An interpretation of the principle of X-ray cargo inspection technology and the features of X-ray sources are presented in this article. As most of the X-ray sources are based on RF electron linear accelerators (linacs), we give a relatively detailed description of the principle and characteristics of linacs. Cargo inspection technologies based on neutron imaging, neutron analysis, nuclear resonance fluorescence and computer tomography are also mentioned here. The main vendors and their products are summarized at the end of the article.

  4. Low energy stages - 'dogbone' muon RLA

    SciTech Connect

    Alex Bogacz

    2005-12-01

    A conceptual design of lower energy stages of muon accelerator is presented. The scheme is based on two superconducting, 200 MHz linacs: a single pass linear pre-accelerator followed by a multi-pass ''dogbone'' recirculating linac (RLA). In the presented scenario, acceleration starts after ionization cooling at 273 MeV/c and proceeds to 5 GeV, where the beam is injected into a complex of FFAG rings for further acceleration. The key conceptual issues are addressed and implemented in the overall acceleration scheme: capture, acceleration, transport and preservation of large phase space of fast decaying species. Beam transport of large-momentum-spread beams is facilitated through appropriate lattice design choices. The proposed linear optics for ''droplet'' return arcs optics is further supplemented with a sextupole correction to suppress chromatic effects contributing to the horizontal emittance dilution.

  5. Electron polarimetry at low energies in Hall C at JLab

    NASA Astrophysics Data System (ADS)

    Gaskell, D.

    2013-11-01

    Although the majority of Jefferson Lab experiments require multi-GeV electron beams, there have been a few opportunities to make electron beam polarization measurements at rather low energies. This proceedings will discuss some of the practical difficulties encountered in performing electron polarimetry via Mo/ller scattering at energies on the order of a few hundred MeV. Prospects for Compton polarimetry at very low energies will also be discussed. While Mo/ller scattering is likely the preferred method for electron polarimetry at energies below 500 MeV, there are certain aspects of the polarimeter and experiment design that must be carefully considered.

  6. A new US energy agenda: US leadership in transition

    SciTech Connect

    Not Available

    1992-11-20

    For the first time since the Carter Administration at the end of 1980, the US is embarked upon energy management beyond laissez faire' free market determination. The election of Bill Clinton to the Presidency could mean the release of years-old pressures to greatly increase efficiency, dramatically reduce hydrocarbon dependency, and curtail pollution to unheard of degrees. Doubtlessly, it will also unleash debates about how to do this without imposing protectionism or further slowing the domestic economy. In this issue a veteran energy analyst, J. Lange Winckler, assesses the changes to be expected. ED supplements the text with graphics that illustrate four scenarios of energy growth and utilization over the next 40 years. This issue also includes the following: (1) the ED Refining Netback Data for the US Gulf and West Coasts, Rotterdam and Singapore as of November 6, 1992; and (2) the ED Fuel Price/Tax Series for countries of the Western Hemisphere, November 1992 Edition.

  7. Composition Measurements near the Second Knee with the Telescope Array Low-Energy Extension (TALE)

    NASA Astrophysics Data System (ADS)

    Belz, J.

    Cosmic rays with energies between 1016.5 and 1018.5 eV exhibit a rich range of features. The energy spectrum changes index at at least two points, known as the "second knee" and the "ankle". There appears to be a composition change in this energy regime as well, which may indicate a shift in predominance from galactic to extragalactic sources. The Telescope Array Low-Energy Extension - planned for construction in Millard County, Utah, USA - stands well poised to make decisive simultaneous measurements of cosmic ray energy spectra and composition in this transition region. Here, we present the results of simulation studies relevant to the design of the TALE detectors, and estimate the sensitivity of TALE to composition changes in the 1017 eV decade.

  8. Low energy lamps and eye lens autofluorescence.

    PubMed

    Walsh, Glyn; Pearce, E Ian

    2010-10-01

    Tungsten filament lamps are rapidly being displaced from the market-place by compact fluorescent lamps. Although the colour temperature and total luminous output of a fluorescent lamp may be similar to that of an incandescent lamp, the output spectrum is very different. The peaks of the mercury vapour spectrum at 365.4nm (UV) and at 435.8nm (blue) are close to the peak fluorescence excitation wavelengths in the human lens, and it has been shown that such fluorescence can lower sensitivity to low contrast objects. This effect could also explain the reported preference for brown, red and yellow tinted lenses often reported by elderly patients, as these coincidentally block the ultraviolet and blue exciting wavelengths.

  9. Design of low energy bunch compressors with space charge effects

    NASA Astrophysics Data System (ADS)

    He, A.; Willeke, F.; Yu, L. H.; Yang, L.; Shaftan, T.; Wang, G.; Li, Y.; Hidaka, Y.; Qiang, J.

    2015-01-01

    In this paper, we explore a method to manipulate low energy electron bunches in a space charge dominated regime, and we use this method to design low energy linac bunch compressors to compress electron bunches in a space charge dominated regime. In the method, we use the space charge effects instead of avoiding them; i.e., we use the space charge forces to generate the required energy chirp instead of the ordinary method which uses the rf accelerating system to generate the chirp. We redefine the concepts of the dispersion function and beta functions in a space charge dominated regime to guide the optimization. Using this method, we study the low energy (5-22 MeV) linac bunch compressor design to produce short (˜150 fs ) and small size (˜30 μ m ) bunches for the electron beam slicing project. The low energy linac bunch compressors work in a space charge dominated regime, and the bunches at the downstream of the gun have a negative energy chirp due to the space charge effects. To provide compression for the negative energy chirped bunch, we design a positive R56 dispersive section using a four-dipole chicane with several quadrupole magnets. We have designed low energy linac bunch compressors with different photocathode rf guns. For example, one linac bunch compressor with the BNL photocathode electron rf gun has achieved a low energy bunch with the 166 fs rms bunch length, 28 and 31 μ m rms beam size in the vertical and horizontal directions, respectively, at 5 MeV with 50 pC charge. Another example with LBNL's very-high frequency gun has achieved a low energy bunch with the 128 fs rms bunch length, 42 and 25 μ m rms beam size in the vertical and horizontal directions, respectively, at 22 MeV with 200 pC charge.

  10. The Effects of Dislocations on the Verwey Transition as Observed by Transmission Electron Microscopy and Low Temperature Magnetic Measurements

    NASA Astrophysics Data System (ADS)

    Lindquist, A. K.; Feinberg, J. M.; Harrison, R. J.; Loudon, J.; Newell, A. J.

    2014-12-01

    Pure magnetite experiences a first order phase transition, called the Verwey transition, at ~120K whereby the mineral's crystal structure changes from cubic to monoclinic. This transformation has a profound effect on the magnetic properties of magnetite. Internal and external stresses have been shown to affect the onset of the Verwey transition, but the processes by which this occurs have not been observed. To further investigate this behavior, we used transmission electron microscopy on deformed magnetite samples to simultaneously image dislocations, magnetic domain walls, and low-temperature twins while cooling through the Verwey transition. To relate the observed changes to more readily-measurable bulk sample magnetic behavior, we made low-temperature magnetic measurements using SQUID magnetometry. According to these low temperature measurements, the temperature of the phase transition is depressed by as much as 6°C in the deformed samples. Combining these two techniques allows us, for the first time, to observe the Verwey transition in a defect-rich area and to observe the manner in which dislocations, and their associated stress fields, influence and impede the growth of twin structures as magnetite is cooled through the Verwey transition.

  11. Porous nanoarchitectures of spinel-type transition metal oxides for electrochemical energy storage systems.

    PubMed

    Park, Min-Sik; Kim, Jeonghun; Kim, Ki Jae; Lee, Jong-Won; Kim, Jung Ho; Yamauchi, Yusuke

    2015-12-14

    Transition metal oxides possessing two kinds of metals (denoted as AxB3-xO4, which is generally defined as a spinel structure; A, B = Co, Ni, Zn, Mn, Fe, etc.), with stoichiometric or even non-stoichiometric compositions, have recently attracted great interest in electrochemical energy storage systems (ESSs). The spinel-type transition metal oxides exhibit outstanding electrochemical activity and stability, and thus, they can play a key role in realising cost-effective and environmentally friendly ESSs. Moreover, porous nanoarchitectures can offer a large number of electrochemically active sites and, at the same time, facilitate transport of charge carriers (electrons and ions) during energy storage reactions. In the design of spinel-type transition metal oxides for energy storage applications, therefore, nanostructural engineering is one of the most essential approaches to achieving high electrochemical performance in ESSs. In this perspective, we introduce spinel-type transition metal oxides with various transition metals and present recent research advances in material design of spinel-type transition metal oxides with tunable architectures (shape, porosity, and size) and compositions on the micro- and nano-scale. Furthermore, their technological applications as electrode materials for next-generation ESSs, including metal-air batteries, lithium-ion batteries, and supercapacitors, are discussed.

  12. Porous nanoarchitectures of spinel-type transition metal oxides for electrochemical energy storage systems.

    PubMed

    Park, Min-Sik; Kim, Jeonghun; Kim, Ki Jae; Lee, Jong-Won; Kim, Jung Ho; Yamauchi, Yusuke

    2015-12-14

    Transition metal oxides possessing two kinds of metals (denoted as AxB3-xO4, which is generally defined as a spinel structure; A, B = Co, Ni, Zn, Mn, Fe, etc.), with stoichiometric or even non-stoichiometric compositions, have recently attracted great interest in electrochemical energy storage systems (ESSs). The spinel-type transition metal oxides exhibit outstanding electrochemical activity and stability, and thus, they can play a key role in realising cost-effective and environmentally friendly ESSs. Moreover, porous nanoarchitectures can offer a large number of electrochemically active sites and, at the same time, facilitate transport of charge carriers (electrons and ions) during energy storage reactions. In the design of spinel-type transition metal oxides for energy storage applications, therefore, nanostructural engineering is one of the most essential approaches to achieving high electrochemical performance in ESSs. In this perspective, we introduce spinel-type transition metal oxides with various transition metals and present recent research advances in material design of spinel-type transition metal oxides with tunable architectures (shape, porosity, and size) and compositions on the micro- and nano-scale. Furthermore, their technological applications as electrode materials for next-generation ESSs, including metal-air batteries, lithium-ion batteries, and supercapacitors, are discussed. PMID:26549729

  13. Energy-microfinance intervention for low income households in India

    NASA Astrophysics Data System (ADS)

    Rao, P. Sharath Chandra

    In India, limited energy access and energy inequity hamper the lives of low income households. Traditional fuels such as firewood and dung cake account for 84 percent and 32 percent of the rural and urban household cooking energy (NSSO, 2007). With 412 million people without access to electricity in 2005, India hosts the world's largest such population (IEA, 2007). But, low income households still spend 9 - 11.7 percent1 of their incomes on inefficient forms of energy while wealthy households spend less than 5 percent on better energy products (Saghir, 2005). Renewable energy technologies coupled with innovative financial products can address the energy access problem facing the low income households in India (MacLean & Siegel, 2007; REEEP, 2009). Nevertheless, the low income households continue to face low access to mainstream finance for purchasing renewable energy technology at terms that meet their monthly energy related expenditure (ESMAP, 2004a; SEEP, 2008a) and low or no access to energy services (Ailawadi & Bhattacharyya, 2006; Modi et. al., 2006). The lack of energy-finance options has left the marginalized population with little means to break the dependence on traditional fuels. This dissertation proposes an energy microfinance intervention to address the present situation. It designed a loan product dedicated to the purchase of renewable energy technologies while taking into account the low and irregular cash flows of the low income households. The arguments presented in this dissertation are based on a six-month pilot project using this product designed and developed by the author in conjunction with a microfinance institution and its low income clients and Energy Service Companies in the state of Karnataka. Finding the right stakeholders and establishing a joint agreement, obtaining grant money for conducting the technology dissemination workshops and forming a clear procedure for commissioning the project, are the key lessons learnt from this study

  14. Signature of a continuous quantum phase transition in non-equilibrium energy absorption: Footprints of criticality on higher excited states

    PubMed Central

    Bhattacharyya, Sirshendu; Dasgupta, Subinay; Das, Arnab

    2015-01-01

    Understanding phase transitions in quantum matters constitutes a significant part of present day condensed matter physics. Quantum phase transitions concern ground state properties of many-body systems, and hence their signatures are expected to be pronounced in low-energy states. Here we report signature of a quantum critical point manifested in strongly out-of-equilibrium states with finite energy density with respect to the ground state and extensive (subsystem) entanglement entropy, generated by an external pulse. These non-equilibrium states are evidently completely disordered (e.g., paramagnetic in case of a magnetic ordering transition). The pulse is applied by switching a coupling of the Hamiltonian from an initial value (λI) to a final value (λF) for sufficiently long time and back again. The signature appears as non-analyticities (kinks) in the energy absorbed by the system from the pulse as a function of λF at critical-points (i.e., at values of λF corresponding to static critical-points of the system). As one excites higher and higher eigenstates of the final Hamiltonian H(λF) by increasing the pulse height , the non-analyticity grows stronger monotonically with it. This implies adding contributions from higher eigenstates help magnifying the non-analyticity, indicating strong imprint of the critical-point on them. Our findings are grounded on exact analytical results derived for Ising and XY chains in transverse field. PMID:26568306

  15. Transitions in low Re pumping by oscillating plate arrays of mayfly nymphs

    NASA Astrophysics Data System (ADS)

    Kiger, Ken; Sensenig, Andrew; Shultz, Jeffrey

    2008-11-01

    Mayfly nymphs are aquatic insects which alter behavior and metabolism to accommodate changes in ambient dissolved oxygen. Many species can generate a ventilation current to compensate for low oxygen levels by beating two linear arrays of plate-like gills that line the lateral edge of the abdomen. The oscillation Reynolds number associated with the gill motion changes with animal size, varying over a span of Re = 2 to 50 depending on age and species. Thus mayflies provide a novel system model for studying ontological changes in pumping mechanisms associated with transitions from a viscous- to inertia-dominated flow. Observation of the detailed 3-D kinematics of the gill motion of the species Centroptilum triangulifer reveal that the mayfly makes a marked transition in stroke motion when Re>5, with a corresponding shift in mean flow from the ventral to the dorsal direction. Results of the time-resolved flow within the inter-gill space shows that for Re>12 the plate motion generates a complex array of bound and shed vortices, which interact to produce an intermittent dorsally directed jet. For the Re<5, distinct bound vortices are still observed, but increased diffusive effects creates vortices which simultaneously envelope several gills, forcing a new flow pattern to emerge. Details of the flow mechanism and its implications will be discussed. This work is supported by NSF under grant CBET-0730907.

  16. Spectroscopy of low lying transitions of He confined in a fullerene cage

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Supriya K.; Mukherjee, Prasanta K.; Fricke, Burkhard

    2016-09-01

    Using time dependent coupled Hartree-Fock(TDCHF) theory, we estimate structural properties such as total energy, ionisation potential, static and dynamic polarizabilities, oscillator strengths and transition probabilities for the first three dipolar excitations 1s2:1Se → 1snp:1Po (n = 2,3,4) and quadrupolar excitations 1s2:1Se → 1snd:1De (n = 3,4,5) of a helium atom placed at the centre of a fullerene cage. We estimate these structural properties using the fullerene cage potential based on experimental findings, including both neutral and charged fullerene potentials. Systematics have been observed with respect to the nature of the charge on fullerene compared to neutral species. We highlight interesting behavior of the excited state wavefunctions for the central atom, leading to altered behavioral patterns of the relevant properties.

  17. Low-energy positron scattering by pyrimidine

    SciTech Connect

    Barbosa, Alessandra Souza; Pastega, Diego F.; Bettega, Márcio H. F.

    2015-12-28

    This work reports elastic integral and differential cross sections for positron collisions with pyrimidine, for energies up to 20 eV. The cross sections were computed with the Schwinger multichannel method in the static plus polarization approximation. We also employed the Born closure procedure to account for the long range potential due to the permanent dipole moment of the molecule. Our results are compared with the experimental total cross section of Zecca et al. [J. Phys. B 43, 215204 (2010)], the experimental grand-total, quasi-elastic integral and differential cross section of Palihawadana et al. [Phys. Rev. A 88, 12717 (2013)]. We also compare our results with theoretical integral and differential cross sections obtained by Sanz et al. [Phys. Rev. A 88, 62704 (2013)] with the R-matrix and the independent atom model with screening-corrected additivity rule methods, and with the results computed by Franz and Gianturco [Phys. Rev. A 88, 042711 (2013)] using model correlation-polarization potentials. The agreement between the theory and the experiment is encouraging.

  18. Radial Flux Distribution of Low-Energy Neutrons.

    ERIC Educational Resources Information Center

    Higinbotham, J.

    1979-01-01

    Describes an experiment designed to illustrate the basic principle involved in the process of moderation of fast neutrons by water, and the monitoring of the low-energy neutron flux using indium as a probe. (GA)

  19. Biological assessments for the low energy demonstration accelerator, 1996

    SciTech Connect

    Cross, S.

    1997-03-01

    This report discusses the biological impact to the area around the Los Alamos National Laboratory of the Low Energy Demonstration Accelerator. In particular the impact to the soils, water quality, vegetation, and wildlife are discussed.

  20. Minimal cooling speed for glass transition in a simple solvable energy landscape model

    NASA Astrophysics Data System (ADS)

    Toledo-Marín, J. Quetzalcóatl; Castillo, Isaac Pérez; Naumis, Gerardo G.

    2016-06-01

    The minimal cooling speed required to form a glass is obtained for a simple solvable energy landscape model. The model, made from a two-level system modified to include the topology of the energy landscape, is able to capture either a glass transition or a crystallization depending on the cooling rate. In this setup, the minimal cooling speed to achieve glass formation is then found to be related with the crystallization relaxation time, energy barrier and with the thermal history. In particular, we obtain that the thermal history encodes small fluctuations around the equilibrium population which are exponentially amplified near the glass transition, which mathematically corresponds to the boundary layer of the master equation. The change in the glass transition temperature is also found as a function of the cooling rate. Finally, to verify our analytical results, a kinetic Monte Carlo simulation was implemented.

  1. Characterization of natural low transition temperature mixtures (LTTMs): Green solvents for biomass delignification.

    PubMed

    Yiin, Chung Loong; Quitain, Armando T; Yusup, Suzana; Sasaki, Mitsuru; Uemura, Yoshimitsu; Kida, Tetsuya

    2016-01-01

    The aim of this work was to characterize the natural low transition temperature mixtures (LTTMs) as promising green solvents for biomass pretreatment with the critical characteristics of cheap, biodegradable and renewable, which overcome the limitations of ionic liquids (ILs). The LTTMs were derived from inexpensive commercially available hydrogen bond acceptor (HBA) and l-malic acid as the hydrogen bond donor (HBD) in distinct molar ratios of starting materials and water. The peaks involved in the H-bonding shifted and became broader for the OH groups. The thermal properties of the LTTMs were not affected by water while the biopolymers solubility capacity of LTTMs was improved with the increased molar ratio of water and treatment temperature. The pretreatment of oil palm biomass was consistence with the screening on solubility of biopolymers. This work provides a cost-effective alternative to utilize microwave hydrothermal extracted green solvents such as malic acid from natural fruits and plants. PMID:26253419

  2. Food systems transition and disruptive low carbon innovation: implications for a food security research agenda.

    PubMed

    Tyfield, David

    2011-07-01

    There is a growing consensus that we are facing epochal challenges in global food security. Moreover, these challenges are multiple and complex. Meeting these challenges will involve nothing less than a wholesale socio-technical transition of the agri-food system. Optimizing the efficacy of the contribution of research to such a food security agenda will probably also need new institutional mechanisms and career structures to facilitate new kinds of collaborations and ongoing, longer-term projects. In short, the multiple challenges of food security demand a different political economy of research for effective intervention by science. In making this argument, the paper summarizes the major findings of a recent report regarding the potential impact of so-called 'disruptive' low-carbon innovations in China.

  3. Low-spin electromagnetic transition probabilities in {sup 102,104}Cd

    SciTech Connect

    Boelaert, N.; Dewald, A.; Fransen, C.; Jolie, J.; Linnemann, A.; Melon, B.; Moeller, O.; Smirnova, N.; Heyde, K.

    2007-05-15

    Lifetimes of low-lying states in {sup 102,104}Cd were determined by using the recoil distance Doppler-shift technique with a plunger device and a Ge array consisting of five HP Ge detectors and one Euroball cluster detector. The experiments were carried out at the Cologne FN Tandem facility using the {sup 92}Mo({sup 12}C,2n){sup 102}Cd reaction at 41 MeV and the {sup 94}Mo({sup 12}C,2n){sup 104}Cd reaction at 42 MeV. The differential decay curve method in coincidence mode was employed to derive the lifetime of the first 2{sup +} state in both nuclei and the lifetime of the 4{sup +} state in {sup 104}Cd. The corresponding reduced E2 transition probabilities have been studied within the framework of the nuclear shell model.

  4. Characterization of natural low transition temperature mixtures (LTTMs): Green solvents for biomass delignification.

    PubMed

    Yiin, Chung Loong; Quitain, Armando T; Yusup, Suzana; Sasaki, Mitsuru; Uemura, Yoshimitsu; Kida, Tetsuya

    2016-01-01

    The aim of this work was to characterize the natural low transition temperature mixtures (LTTMs) as promising green solvents for biomass pretreatment with the critical characteristics of cheap, biodegradable and renewable, which overcome the limitations of ionic liquids (ILs). The LTTMs were derived from inexpensive commercially available hydrogen bond acceptor (HBA) and l-malic acid as the hydrogen bond donor (HBD) in distinct molar ratios of starting materials and water. The peaks involved in the H-bonding shifted and became broader for the OH groups. The thermal properties of the LTTMs were not affected by water while the biopolymers solubility capacity of LTTMs was improved with the increased molar ratio of water and treatment temperature. The pretreatment of oil palm biomass was consistence with the screening on solubility of biopolymers. This work provides a cost-effective alternative to utilize microwave hydrothermal extracted green solvents such as malic acid from natural fruits and plants.

  5. Magnetic and structural phase transitions in erbium at low temperatures and high pressures

    SciTech Connect

    Thomas, Sarah A.; Tsoi, Georgiy M.; Wenger, Lowell E.; Vohra, Yogesh K.

    2012-02-07

    Electrical resistance and crystal structure measurements have been carried out on polycrystalline erbium (Er) at temperatures down to 10 K and pressures up to 20 GPa. An abrupt change in the slope of the resistance is observed with decreasing temperature below 84 K, which is associated with the c-axis modulated (CAM) antiferromagnetic (AFM) ordering of the Er moments. With increasing pressure the temperature of the resistance slope change and the corresponding AFM ordering temperature decrease until vanishing above 10.6 GPa. The disappearance of the slope change in the resistance occurs at similar pressures where the hcp structural phase of Er is transformed to a nine-layer {alpha}-Sm structural phase, as confirmed by our high-pressure synchrotron x-ray diffraction studies. These results suggest that the disappearance in the AFM ordering of Er moments is strongly correlated to the structural phase transition at high pressures and low temperatures.

  6. Coulomb effects in low-energy nuclear fragmentation

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah

    1993-01-01

    Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.

  7. Power conditioning for low-voltage piezoelectric stack energy harvesters

    NASA Astrophysics Data System (ADS)

    Skow, E.; Leadenham, S.; Cunefare, K. A.; Erturk, A.

    2016-04-01

    Low-power vibration and acoustic energy harvesting scenarios typically require a storage component to be charged to enable wireless sensor networks, which necessitates power conditioning of the AC output. Piezoelectric beam-type bending mode energy harvesters or other devices that operate using a piezoelectric element at resonance produce high voltage levels, for which AC-DC converters and step-down DC-DC converters have been previously investigated. However, for piezoelectric stack energy harvesters operating off-resonance and producing low voltage outputs, a step-up circuit is required for power conditioning, such as seen in electromagnetic vibration energy scavengers, RF communications, and MEMS harvesters. This paper theoretically and experimentally investigates power conditioning of a low-voltage piezoelectric stack energy harvester.

  8. Correlation among low-energy four-nucleon observables

    NASA Astrophysics Data System (ADS)

    Adhikari, Sadhan K.

    1981-07-01

    We study the correlation among s-wave low-energy four-nucleon observables by using a simplified dispersion theoretic (ND) approach. We find that the triton binding energy, its asymptotic normalization parameter, the deuteron exchange left-hand cut, and the nucleon-trinucleon (N-t) scattering length control the low-energy N-t system. The isospin one channel is insensitive to the asymptotic normalization parameter of the triton. The effective range function k δ for the isospin zero spin singlet N-t system has a pole whose position and residue are strongly correlated with the N-t scattering length. In this case the four-nucleon system (in our model) has an excited state whose binding energy and asymptotic normalization parameter are also correlated with the N-t scattering length. [NUCLEAR REACTIONS s-wave nucleon-trinucleon systems, spin-isospin channels, ND approach, low-energy correlations.

  9. Photon Strength Function at Low Energies in 95Mo

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Bernstein, L. A.; Allmond, J. M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Krtička, M.; Lake, P. T.; Larsen, A. C.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.

    2014-05-01

    A new and model-independent experimental method has been developed to determine the energy dependence of the photon strength function. It is designed to study statistical feeding from the quasi continuum to individual low-lying discrete levels. This new technique is presented and results for 95Mo are compared to data from the University of Oslo. In particular, questions regarding the existence of the low-energy enhancement in the photon strength function are addressed.

  10. Surface Passivation and Junction Formation Using Low Energy Hydrogen Implants

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.

    1985-01-01

    New applications for high current, low energy hydrogen ion implants on single crystal and polycrystal silicon grain boundaries are discussed. The effects of low energy hydrogen ion beams on crystalline Si surfaces are considered. The effect of these beams on bulk defects in crystalline Si is addressed. Specific applications of H+ implants to crystalline Si processing are discussed. In all of the situations reported on, the hydrogen beams were produced using a high current Kaufman ion source.

  11. Atomic Oxygen Energy in Low Frequency Hyperthermal Plasma Ashers

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Miller, Sharon K R.; Kneubel, Christian A.

    2014-01-01

    Experimental and analytical analysis of the atomic oxygen erosion of pyrolytic graphite as well as Monte Carlo computational modeling of the erosion of Kapton H (DuPont, Wilmington, DE) polyimide was performed to determine the hyperthermal energy of low frequency (30 to 35 kHz) plasma ashers operating on air. It was concluded that hyperthermal energies in the range of 0.3 to 0.9 eV are produced in the low frequency air plasmas which results in texturing similar to that in low Earth orbit (LEO). Monte Carlo computational modeling also indicated that such low energy directed ions are fully capable of producing the experimentally observed textured surfaces in low frequency plasmas.

  12. Low transition temperature mixtures as innovative and sustainable CO2 capture solvents.

    PubMed

    Zubeir, Lawien F; Lacroix, Mark H M; Kroon, Maaike C

    2014-12-11

    The potential of three newly discovered low transition temperature mixtures (LTTMs) is explored as sustainable substituents for the traditional carbon dioxide (CO2) absorbents. LTTMs are mixtures of two solid compounds, a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA), which form liquids upon mixing with melting points far below those of the individual compounds. In this work the HBD is lactic acid and the HBAs are tetramethylammonium chloride, tetraethylammonium chloride, and tetrabutylammonium chloride. These compounds were found to form LTTMs for the first time at molar ratios of HBD:HBA = 2:1. First, the LTTMs were characterized by determining the thermal operating window (e.g., decomposition temperature and glass transition temperature) and the physical properties (e.g., density and viscosity). Thereafter, the phase behavior of CO2 with the LTTMs has been measured using a gravimetric magnetic suspension balance operating in the static mode at 308 and 318 K and pressures up to 2 MPa. The CO2 solubility increased with increasing chain length, increasing pressure, and decreasing temperature. The Peng-Robinson equation of state was applied to correlate the phase equilibria. From the solubility data, thermodynamic parameters were determined (e.g., Henry's law coefficient and enthalpy of absorption). The heat of absorption was found to be similar to that in conventional physical solvents (-11.21 to -14.87 kJ·mol(-1)). Furthermore, the kinetics in terms of the diffusion coefficient of CO2 in all LTTMs were determined (10(-11)-10(-10) m(2)·s(-1)). Even though the CO2 solubilities in the studied LTTMs were found to be slightly lower than those in thoroughly studied conventional physical solvents, LTTMs are a promising new class of absorbents due to their low cost, their environmentally friendly character, and their easy tunability, allowing further optimization for carbon capture.

  13. Shakeup in soft-x-ray emission. I. The low-energy tail

    NASA Astrophysics Data System (ADS)

    Livins, Peteris; Schnatterly, S. E.

    1988-04-01

    The L soft-x-ray emission spectra for Al and Si, and the K emission for graphite and diamond are analyzed, taking into account the effects of multielectron transitions which produce a low-energy tail on the main band. Through an appropriate transformation on the initial states, it is shown that the final-state rule of Von Barth and Grossman is a direct result of exchange. A ``Pauli rigidity'' forces the initial-state wave function to approach that of the final state, except near the Fermi energy. An assumption of random phases allows a formal solution that includes single-particle shakeup events to all orders. It is argued that a low-energy feature of silicon is structure due to the shakeup of single-particle-like excitations rather than a plasmon satellite.

  14. Energy and environmental policy in a period of transition

    SciTech Connect

    Stalon, C.G.

    1995-12-31

    This paper discusses governance aspects of electric industry restructuring. The creation and preservation of a governance system to ensure reliable and efficient trades within interconnected and independent trading areas is the main topic. The closely related issue of defining and imposing responsibilities on non-utility generators is also discussed in detail. It is recommended that the Federal Energy Regulatory Commission promote private governance of interconnections. 1 tab.

  15. Database of Low-e Storm Window Energy Performance across U.S. Climate Zones

    SciTech Connect

    Culp, Thomas D.; Cort, Katherine A.

    2014-09-04

    This is an update of a report that describes process, assumptions, and modeling results produced Create a Database of U.S. Climate-Based Analysis for Low-E Storm Windows. The scope of the overall effort is to develop a database of energy savings and cost effectiveness of low-E storm windows in residential homes across a broad range of U.S. climates using the National Energy Audit Tool (NEAT) and RESFEN model calculations. This report includes a summary of the results, NEAT and RESFEN background, methodology, and input assumptions, and an appendix with detailed results and assumptions by cliamte zone.

  16. Low molecular weight compounds with transition metals as free radical scavengers and novel therapeutic agents.

    PubMed

    Bencini, Andrea; Failli, Paola; Valtancoli, Barbara; Bani, Daniele

    2010-07-01

    Molecules able to modulate the levels of endogenous free radicals, such as reactive oxygen species (ROS) and nitric oxide (NO), are of pivotal interest for pharmacological and pharmaceutical sciences because of their potential therapeutic relevance. In fact, ROS and NO, which are normal products of cell metabolism, may play a dual beneficial/deleterious role, depending on local concentration and mode of generation. As such, they have been identified as key pathogenic factors for many inflammatory, vascular dysfunctional and degenerative disorders, including atherosclerosis, hypertension, cardiovascular and neurodegenerative diseases, cancer, diabetes mellitus, and ageing. Therefore, the identification and characterization of novel antioxidant/free radical scavenger molecules may expand the current therapeutic implements for the treatment and prevention of the above diseases. In this perspective, low molecular weight complexes of transition metals with organic scaffolds are viewed and investigated as promising pharmaceutical agents. These complexes take advantage of the known principles of inorganic chemistry, i.e. the ability of transition metals, Fe(II), Co(II), Mn(II) and Ru(II), to bind to and react with NO and/or ROS, to counterbalance excessive endogenous free radical generation in biological systems. Among NO scavengers, representative examples are iron complexes with dithiocarbamates or ruthenium compounds with polyamine-polycarboxylate scaffolds; on the other hand, manganese-based molecules appear effective as ROS scavengers. Of note, Mn(II)-containing molecules, currently under study as ROS scavengers, have major functional similarities to Mn-superoxide dismutase (SOD), a Mn-containing enzyme acting as potent endogenous anti-oxidant. In this article, we briefly summarize the state-of-the-art concerning the chemical and biological properties of transition metal ion complexes with low molecular weight synthetic ligands as ROS/NO scavengers provided with

  17. Low molecular weight compounds with transition metals as free radical scavengers and novel therapeutic agents.

    PubMed

    Bencini, Andrea; Failli, Paola; Valtancoli, Barbara; Bani, Daniele

    2010-07-01

    Molecules able to modulate the levels of endogenous free radicals, such as reactive oxygen species (ROS) and nitric oxide (NO), are of pivotal interest for pharmacological and pharmaceutical sciences because of their potential therapeutic relevance. In fact, ROS and NO, which are normal products of cell metabolism, may play a dual beneficial/deleterious role, depending on local concentration and mode of generation. As such, they have been identified as key pathogenic factors for many inflammatory, vascular dysfunctional and degenerative disorders, including atherosclerosis, hypertension, cardiovascular and neurodegenerative diseases, cancer, diabetes mellitus, and ageing. Therefore, the identification and characterization of novel antioxidant/free radical scavenger molecules may expand the current therapeutic implements for the treatment and prevention of the above diseases. In this perspective, low molecular weight complexes of transition metals with organic scaffolds are viewed and investigated as promising pharmaceutical agents. These complexes take advantage of the known principles of inorganic chemistry, i.e. the ability of transition metals, Fe(II), Co(II), Mn(II) and Ru(II), to bind to and react with NO and/or ROS, to counterbalance excessive endogenous free radical generation in biological systems. Among NO scavengers, representative examples are iron complexes with dithiocarbamates or ruthenium compounds with polyamine-polycarboxylate scaffolds; on the other hand, manganese-based molecules appear effective as ROS scavengers. Of note, Mn(II)-containing molecules, currently under study as ROS scavengers, have major functional similarities to Mn-superoxide dismutase (SOD), a Mn-containing enzyme acting as potent endogenous anti-oxidant. In this article, we briefly summarize the state-of-the-art concerning the chemical and biological properties of transition metal ion complexes with low molecular weight synthetic ligands as ROS/NO scavengers provided with

  18. Transitions in Convection of a Low Prandtl Number Fluid Driven by a Horizontal Temperature Gradient

    NASA Astrophysics Data System (ADS)

    Hung, Ming-Cheng

    The transitions in convection of a low Prandtl number fluid (mercury) contained in enclosed rectangular cavities driven by horizontal temperature gradients were investigated. These cavities have insulating top, bottom and side boundaries. The other two end walls are highly conducting. The temperatures on the conducting walls were varied to control the temperature gradient inside. Both the temperature and the velocity of the fluid inside the cavity were measured. A traversing system allowed the probe position to be changed with the cavity always sealed. The temperature gradient, controlled by a computer, was ramped very slowly. At every 0.2 or 0.12 degree the ramping was held and a data file of several hours was taken. The Prandtl number of the fluid was varied from 0.025 to 0.035 by changing the average temperature. The cavity size effect on the transitions was investigated. The primary (large) cavity had aspect ratio (length:height:width) of 17.8:1:17.8 (height = 0.9 cm). The other cavities for size effect investigation were shorter and narrower. Fourier transform was used to analyze the time series. Phase portraits were constructed in 3d using time delay method and correlation dimensions were computed for some trajectories. For the large cavity, the observed onset of the longitudinal oscillatory state at Grashof number Gr = 18490 was far above the predicted value of 10610 for an infinite long cavity (height/length = 0). At low Grashof numbers, the flow was time independent. As Gr was increased, it changed to a noisy state with a periodic component and then became purely chaotic. Finally the longitudinal oscillatory state appeared with two frequencies and noise. The longitudinal oscillatory state was observed to be a standing wave with a wavelength of about 3 cm. The critical Gr was affected by the cavity width and length. The narrower the cavity, the more stable the flow. The critical Gr for oscillation decreased as the length was increased. An unusual

  19. State transitions redistribute rather than dissipate energy between the two photosystems in Chlamydomonas.

    PubMed

    Nawrocki, Wojciech J; Santabarbara, Stefano; Mosebach, Laura; Wollman, Francis-André; Rappaport, Fabrice

    2016-01-01

    Photosynthesis converts sunlight into biologically useful compounds, thus fuelling practically the entire biosphere. This process involves two photosystems acting in series powered by light harvesting complexes (LHCs) that dramatically increase the energy flux to the reaction centres. These complexes are the main targets of the regulatory processes that allow photosynthetic organisms to thrive across a broad range of light intensities. In microalgae, one mechanism for adjusting the flow of energy to the photosystems, state transitions, has a much larger amplitude than in terrestrial plants, whereas thermal dissipation of energy, the dominant regulatory mechanism in plants, only takes place after acclimation to high light. Here we show that, at variance with recent reports, microalgal state transitions do not dissipate light energy but redistribute it between the two photosystems, thereby allowing a well-balanced influx of excitation energy. PMID:27249564

  20. Nuclear Energy R&D Imperative 3: Enable a Transition Away from Fossil Fuel in the Transportation and Industrial Sectors

    SciTech Connect

    David Petti; J. Stephen Herring

    2010-03-01

    As described in the Department of Energy Office of Nuclear Energy’s Nuclear Energy R&D Roadmap, nuclear energy can play a significant role in supplying energy for a growing economy while reducing both our dependence on foreign energy supplies and emissions from the burning of fossil fuels. The industrial and transportation sectors are responsible for more than half of the greenhouse gas emissions in the U.S., and imported oil supplies 70% of the energy used in the transportation sector. It is therefore important to examine the various ways nuclear energy can facilitate a transition away from fossil fuels to secure environmentally sustainable production and use of energy in the transportation and manufacturing industry sectors. Imperative 3 of the Nuclear Energy R&D Roadmap, entitled “Enable a Transition Away from Fossil Fuels by Producing Process Heat for use in the Transportation and Industrial Sectors”, addresses this need. This document presents an Implementation Plan for R&D efforts related to this imperative. The expanded use of nuclear energy beyond the electrical grid will contribute significantly to overcoming the three inter-linked energy challenges facing U.S. industry: the rising and volatile prices for premium fossil fuels such as oil and natural gas, dependence on foreign sources for these fuels, and the risks of climate change resulting from carbon emissions. Nuclear energy could be used in the industrial and transportation sectors to: • Generate high temperature process heat and electricity to serve industrial needs including the production of chemical feedstocks for use in manufacturing premium fuels and fertilizer products, • Produce hydrogen for industrial processes and transportation fuels, and • Provide clean water for human consumption by desalination and promote wastewater treatment using low-grade nuclear heat as a useful additional benefit. Opening new avenues for nuclear energy will significantly enhance our nation’s energy

  1. Properties of nuclei and elementary particles at low and intermediate energies. Progress report, July 1992--August 1993

    SciTech Connect

    Boehm, F.

    1993-12-31

    Work reported relate to: a 12 ton low energy neutrino detector for neutrino oscillation studies at the San Onofre Reactor Station; new limits on the 17 keV neutrino; time reversal and parity tests for hindered nuclear gamma transitions; and theory of nuclear structure and its application.

  2. Pressure-Induced Structural Transition and Enhancement of Energy Gap of CuAlO2

    NASA Astrophysics Data System (ADS)

    Nakanishi, Akitaka

    2011-02-01

    By using first-principles calculations, we studied the stable crystal structures and energy gaps of CuAlO2 under high pressure. Our simulation shows that CuAlO2 transforms from a delafossite structure to a leaning delafossite structure. The critical pressure of the transition was determined to be 60 GPa. The energy gap of CuAlO2 increases through the structural transition due to the enhanced covalency of Cu 3d and O 2p states. We found that a chalcopyrite structure does not appear as a stable structure under high pressure.

  3. Energy levels and transition probabilities in doubly-ionized erbium (Er III).

    NASA Astrophysics Data System (ADS)

    Wyart, J.-F.; Blaise, J.; Bidelman, W. P.; Cowley, C. R.

    1997-11-01

    The spectrum of Er III reported by Becher (1966) was reanalysed with the support of new predictions of energies and transition probabilities. The number of energy levels was increased from 45 to 115, including two levels of 4f117s and the levels 3F3, 3F2 and 1G4 of the ground configuration 4f12. All 470 classified lines are reported with transition probabilities for most of them. Several of these lines had not yet been attributed to Er III in the spectrum of the star HR 465.

  4. Relativistic M-subshell radiationless transition probabilities and energies for Zn, Cd and Hg

    SciTech Connect

    Sampaio, J.M.; Parente, F.; Indelicato, P.; Marques, J.P.

    2014-09-15

    Theoretical calculations of radiationless transition probabilities and energies for M-subshell vacancies in Zn, Cd, and Hg are tabulated using the Dirac–Fock method. Transition probabilities between an initial vacancy state and a final two-vacancies state are presented for each initial and final atomic angular momentum quantum number. Calculations were performed in the single configuration approach with the Breit interaction, self-energy and (Uehling) vacuum polarization corrections included in the self-consistent method. Higher-order retardation corrections and QED effects were also included as perturbations.

  5. A compact, versatile low-energy electron beam ion source

    SciTech Connect

    Zschornack, G.; König, J.; Schmidt, M.; Thorn, A.

    2014-02-15

    A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies.

  6. Nuclear phenomena in low-energy nuclear reaction research.

    PubMed

    Krivit, Steven B

    2013-09-01

    This is a comment on Storms E (2010) Status of Cold Fusion, Naturwissenschaften 97:861-881. This comment provides the following remarks to other nuclear phenomena observed in low-energy nuclear reactions aside from helium-4 make significant contributions to the overall energy balance; and normal hydrogen, not just heavy hydrogen, produces excess heat.

  7. Modeling the Oil Transition: A Summary of the Proceedings of the DOE/EPA Workshop on the Economic and Environmental Implications of Global Energy Transitions

    SciTech Connect

    Greene, David L

    2007-02-01

    The global energy system faces sweeping changes in the next few decades, with potentially critical implications for the global economy and the global environment. It is important that global institutions have the tools necessary to predict, analyze and plan for such massive change. This report summarizes the proceedings of an international workshop concerning methods of forecasting, analyzing, and planning for global energy transitions and their economic and environmental consequences. A specific case, it focused on the transition from conventional to unconventional oil and other energy sources likely to result from a peak in non-OPEC and/or global production of conventional oil. Leading energy models from around the world in government, academia and the private sector met, reviewed the state-of-the-art of global energy modeling and evaluated its ability to analyze and predict large-scale energy transitions.

  8. Wind Power: A Renewable Energy Source for Mars Transit Vehicle

    NASA Technical Reports Server (NTRS)

    Flynn, Michael; Kohout, Lisa; Kliss, Mark (Technical Monitor)

    1998-01-01

    The Martian environment presents significant design challenges for the development of power generation systems. Nuclear-based systems may not be available due to political and safety concerns. The output of photovoltaics are limited by a solar intensity of 580 W/sqm as compared to 1353 W/sqm on Earth. The presence of dust particles in the Mars atmosphere will further reduce the photovoltaic output. Also, energy storage for a 12-hour night period must be provided. In this challenging environment, wind power generation capabilities may provide a viable option as a Martian power generation system. This paper provides an analysis of the feasibility of such a system.

  9. Nozzle wall roughness effects on free-stream noise and transition in the pilot low-disturbance tunnel

    NASA Technical Reports Server (NTRS)

    Creel, T. R., Jr.; Beckwith, I. E.; Chen, F. J.

    1985-01-01

    An investigation at Mach 3.5 into the effects of nozzle wall roughness on free stream pressure fluctuations and cone transition Reynolds numbers was conducted in the pilot low disturbance tunnel at the Langley Research Center. Nozzle wall roughness caused by either particle deposits or imperfections in surface finish increased free stream noise levels and reduced the transition Reynolds numbers on a cone mounted in the test rhombus.

  10. Energy-filtered Electron Transport Structures for Low-power Low-noise 2-D Electronics

    PubMed Central

    Pan, Xuan; Qiu, Wanzhi; Skafidas, Efstratios

    2016-01-01

    In addition to cryogenic techniques, energy filtering has the potential to achieve high-performance low-noise 2-D electronic systems. Assemblies based on graphene quantum dots (GQDs) have been demonstrated to exhibit interesting transport properties, including resonant tunnelling. In this paper, we investigate GQDs based structures with the goal of producing energy filters for next generation lower-power lower-noise 2-D electronic systems. We evaluate the electron transport properties of the proposed GQD device structures to demonstrate electron energy filtering and the ability to control the position and magnitude of the energy passband by appropriate device dimensioning. We also show that the signal-to-thermal noise ratio performance of the proposed nanoscale device can be modified according to device geometry. The tunability of two-dimensional GQD structures indicates a promising route for the design of electron energy filters to produce low-power and low-noise electronics. PMID:27796343

  11. Sequence dependent free energy profiles of localized B- to A-form transition of DNA in water

    NASA Astrophysics Data System (ADS)

    Kulkarni, Mandar; Mukherjee, Arnab

    2013-10-01

    DNA carries an inherent polymorphism, which surfaces under various external conditions. While B-form remains predominant under normal physiological conditions for most of the DNA sequences, low humidity and increased ion concentration cause B- to A-form transition. Certain proteins and molecules also sometimes cause local deformation of the DNA to the specific A-form. Previous experimental and computational studies focused on the overall B- to A-form transition. Here for the first time we investigated thermodynamics and mechanism of B- to A-form transition in water for various DNA sequences at a local dinucleotide base pair level. We introduced a new reaction coordinate Zp', based on the unique order parameter Zp, to drive B- to A-form transition locally and thereby calculate free energy profiles for the same for all the ten different dinucleotide steps embedded in a twelve base pair DNA. Results show that the trend of "A" and "B" philicity observed in experiment is preserved even at this local dinucleotide level, indicating its localized origin. Higher free energy cost obtained here is attributed to the cost of creating B/A junctions along with formation of B->A transition at dimer level. We find that while water energetically stabilizes A-form for all the ten different dinucleotide steps to various extents, entropy acts against it. Therefore, we find that the stability of B-form DNA in water is entropic in origin. Mechanism of the conversion appears to be triggered by Slide; however, backbone parameters change concertedly.

  12. Cluster structure of a low-energy resonance in tetraneutron

    SciTech Connect

    Lashko, Yu. A. Filippov, G. F.

    2008-02-15

    We theoretically investigate the possibility for a tetraneutron to exist as a low-energy resonance state. We explore a microscopic model based on the assumption that the tetraneutron can be treated as a compound system, where {sup 3}n + n and {sup 2}n + {sup 2}n coupled cluster configurations coexist. The influence of the Pauli principle on the kinetic energy of the relative motion of the neutron clusters is shown to result in their attraction. The strength of such attraction is high enough to ensure the existence of a low-energy resonance in the tetraneutron, provided that the oscillator length is large enough.

  13. Strong flux of low-energy neutrons produced by thunderstorms.

    PubMed

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed. PMID:22540588

  14. IONS (ANURADHA): Ionization states of low energy cosmic rays

    NASA Technical Reports Server (NTRS)

    Biswas, S.; Chakraborti, R.; Cowsik, R.; Durgaprasad, N.; Kajarekar, P. J.; Singh, R. K.; Vahia, M. N.; Yadav, J. S.; Dutt, N.; Goswami, J. N.

    1987-01-01

    IONS (ANURADHA), the experimental payload designed specifically to determine the ionization states, flux, composition, energy spectra and arrival directions of low energy (10 to 100 MeV/amu) anomalous cosmic ray ions of helium to iron in near-Earth space, had a highly successful flight and operation Spacelab-3 mission. The experiment combines the accuracy of a highly sensitive CR-39 nuclear track detector with active components included in the payload to achieve the experimental objectives. Post-flight analysis of detector calibration pieces placed within the payload indicated no measurable changes in detector response due to its exposure in spacelab environment. Nuclear tracks produced by alpha-particles, oxygen group and Fe ions in low energy anomalous cosmic rays were identified. It is calculated that the main detector has recorded high quality events of about 10,000 alpha-particles and similar number of oxygen group and heavier ions of low energy cosmic rays.

  15. Light element production by low energy nuclei from massive stars

    NASA Technical Reports Server (NTRS)

    Vangioni-Flam, E.; Casse, M.; Ramaty, R.

    1997-01-01

    The Orion complex is a source of gamma rays attributed to the de-excitation of fast carbon and oxygen nuclei excited through interactions with ambient hydrogen and helium. This has consequences for the production and evolution of light isotopes in the Galaxy, as massive stars appear as prolific sources of C-O rich low energy nuclei. The different stages of massive star evolution are considered in relation to the acceleration of nuclei to moderate energies. It is concluded that the low energy nuclear component originating from massive stars plays a larger role than the usual Galactic cosmic rays in shaping the evolution of Li-6, Be-9, B-10 and B-11, especially in the early Galactic evolution. The enhancement of the B-11/B-10 ratio observed in meteorites and in the interstellar medium is attributed to the interaction of low energy carbon nuclei with ambient H and to a lesser degree, to neutrino spallation.

  16. Spectroscopic elucidation of uncoupled transition energies in the major photosynthetic light-harvesting complex, LHCII

    PubMed Central

    Schlau-Cohen, Gabriela S.; Calhoun, Tessa R.; Ginsberg, Naomi S.; Ballottari, Matteo; Bassi, Roberto; Fleming, Graham R.

    2010-01-01

    Electrostatic couplings between chromophores in photosynthetic pigment–protein complexes, and interactions of pigments with the surrounding protein environment, produce a complicated energy landscape of delocalized excited states. The resultant electronic structure absorbs light and gives rise to energy transfer steps that direct the excitation toward a site of charge separation with near unity quantum efficiency. Knowledge of the transition energies of the uncoupled chromophores is required to describe how the wave functions of the individual pigments combine to form this manifold of delocalized excited states that effectively harvests light energy. In an investigation of the major light-harvesting complex of photosystem II (LHCII), we develop a method based on polarized 2D electronic spectroscopy to experimentally access the energies of the S0–S1 transitions in the chromophore site basis. Rotating the linear polarization of the incident laser pulses reveals previously hidden off-diagonal features. We exploit the polarization dependence of energy transfer peaks to find the angles between the excited state transition dipole moments. We show that these angles provide a spectroscopic method to directly inform on the relationship between the delocalized excitons and the individual chlorophylls through the site energies of the uncoupled chromophores. PMID:20622154

  17. Precise Determination of the Lyman-1 Transition Energy in Hydrogen-like Gold Ions with Microcalorimeters

    NASA Astrophysics Data System (ADS)

    Kraft-Bermuth, S.; Andrianov, V.; Bleile, A.; Echler, A.; Egelhof, P.; Grabitz, P.; Kilbourne, C.; Kiselev, O.; McCammon, D.; Scholz, P.

    2014-09-01

    The precise determination of the transition energy of the Lyman-1 line in hydrogen-like heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. We report the determination of the Lyman-1 transition energy of gold ions (Au) with microcalorimeters at the experimental storage ring at GSI. X-rays produced by the interaction of 125 MeV/u Au ions with an internal argon gas-jet target were detected. The detector array consisted of 14 pixels with silicon thermistors and Sn absorbers, for which an energy resolution of 50 eV for an X-ray energy of 59.5 keV was obtained in the laboratory. The Lyman-1 transition energy was determined for each pixel in the laboratory frame, then transformed into the emitter frame and averaged. A Dy-159 source was used for energy calibration. The absolute positions of the detector pixels, which are needed for an accurate correction of the Doppler shift, were determined by topographic measurements and by scanning a collimated Am-241 source across the cryostat window. The energy of the Lyman-1 line in the emitter frame is eV, in good agreement with theoretical predictions. The systematic error is dominated by the uncertainty in the position of the cryostat relative to the interaction region of beam and target.

  18. The problem of low energy particle measurements in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Whipple, E. C., Jr.

    1978-01-01

    The accurate measurement of low energy (less than 100 eV) particle properties in the magnetosphere has been difficult, partly because of the low density of such particles, but more particularly because of spacecraft interference effects. Some early examples of how these phenomena have affected particle measurements on an OGO spacecraft are presented. Data obtained with the UCSD particle detectors on ATS-6 are then presented showing how some of these difficulties have been partially overcome. Future measurements of low energy particles in the magnetosphere can be improved by: (1) improving the low energy resolution of detectors; (2) building electrostatically clean spacecraft; (3) controlling spacecraft potential; and (4) using auxiliary measurements, particularly wave data.

  19. Low-energy physics of high-temperature superconductors

    SciTech Connect

    Emery, V.J. . Physics Dept.); Kivelson, S.A. . Dept. of Physics)

    1992-01-01

    It is argued that the low-energy properties of high temperature superconductors are dominated by the interaction between the mobile holes and a particular class of collective modes, corresponding to local large-amplitude low-energy fluctuations in the hole density. The latter are a consequence of the competition between the effects of long-range Coulomb interactions and the tendency of a low concentration of holes in an antiferromagnet to phase separate. The low-energy behavior of the system is governed by the same fixed point as the two-channel Kondo problem, which accounts for the universality'' of the properties of the cuprate superconductors. Predictions of the optical properties and the spin dynamics are compared with experiment. The pairing resonance of the two Kondo problem gives a mechanism of high temperature superconductivity with an unconventional symmetry of the order parameter.

  20. Low-energy physics of high-temperature superconductors

    SciTech Connect

    Emery, V.J.; Kivelson, S.A.

    1992-09-01

    It is argued that the low-energy properties of high temperature superconductors are dominated by the interaction between the mobile holes and a particular class of collective modes, corresponding to local large-amplitude low-energy fluctuations in the hole density. The latter are a consequence of the competition between the effects of long-range Coulomb interactions and the tendency of a low concentration of holes in an antiferromagnet to phase separate. The low-energy behavior of the system is governed by the same fixed point as the two-channel Kondo problem, which accounts for the ``universality`` of the properties of the cuprate superconductors. Predictions of the optical properties and the spin dynamics are compared with experiment. The pairing resonance of the two Kondo problem gives a mechanism of high temperature superconductivity with an unconventional symmetry of the order parameter.

  1. Information Content of the Low-Energy Electric Dipole Strength: Correlation Analysis

    SciTech Connect

    Reinhard, P.-G.; Nazarewicz, Witold

    2013-01-01

    Background: Recent experiments on the electric dipole (E1) polarizability in heavy nuclei have stimulated theoretical interest in the low-energy electric dipole strength, both isovector and isoscalar. Purpose: We study the information content carried by the electric dipole strength with respect to isovector and isoscalar indicators characterizing bulk nuclear matter and finite nuclei. To separate isoscalar and isovector modes, and low-energy strength and giant resonances, we analyze the E1 strength as a function of the excitation energy E and momentum transfer q. Methods: We use the self-consistent nuclear density functional theory with Skyrme energy density functionals, augmented by the random phase approximation, to compute the E1 strength and covariance analysis to assess correlations between observables. Calculations are performed for the spherical, doubly magic nuclei 208Pb and 132Sn. Results: We demonstrate that E1 transition densities in the low-energy region below the giant dipole resonance exhibit appreciable state dependence and multinodal structures, which are fingerprints of weak collectivity. The correlation between the accumulated low-energy strength and the symmetry energy is weak, and dramatically depends on the energy cutoff assumed. On the other hand, a strong correlation is predicted between isovector indicators and the accumulated isovector strength at E around 20 MeV and momentum transfer q 0.65 fm 1. Conclusions: Momentum- and coordinate-space patterns of the low-energy dipole modes indicate a strong fragmentation into individual particle-hole excitations. The global measure of low-energy dipole strength correlates poorly with the nuclear symmetry energy and other isovector characteristics. Consequently, our results do not support the suggestion that there exists a collective pygmy dipole resonance, which is a strong indicator of nuclear isovector properties. By considering nonzero values of momentum transfer, one can isolate individual

  2. Enhanced production of low energy electrons by alpha particle impact.

    PubMed

    Kim, Hong-Keun; Titze, Jasmin; Schöffler, Markus; Trinter, Florian; Waitz, Markus; Voigtsberger, Jörg; Sann, Hendrik; Meckel, Moritz; Stuck, Christian; Lenz, Ute; Odenweller, Matthias; Neumann, Nadine; Schössler, Sven; Ullmann-Pfleger, Klaus; Ulrich, Birte; Fraga, Rui Costa; Petridis, Nikos; Metz, Daniel; Jung, Annika; Grisenti, Robert; Czasch, Achim; Jagutzki, Ottmar; Schmidt, Lothar; Jahnke, Till; Schmidt-Böcking, Horst; Dörner, Reinhard

    2011-07-19

    Radiation damage to living tissue stems not only from primary ionizing particles but to a substantial fraction from the dissociative attachment of secondary electrons with energies below the ionization threshold. We show that the emission yield of those low energy electrons increases dramatically in ion-atom collisions depending on whether or not the target atoms are isolated or embedded in an environment. Only when the atom that has been ionized and excited by the primary particle impact is in immediate proximity of another atom is a fragmentation route known as interatomic Coulombic decay (ICD) enabled. This leads to the emission of a low energy electron. Over the past decade ICD was explored in several experiments following photoionization. Most recent results show its observation even in water clusters. Here we show the quantitative role of ICD for the production of low energy electrons by ion impact, thus approaching a scenario closer to that of radiation damage by alpha particles: We choose ion energies on the maximum of the Bragg peak where energy is most efficiently deposited in tissue. We compare the electron production after colliding He(+) ions on isolated Ne atoms and on Ne dimers (Ne(2)). In the latter case the Ne atom impacted is surrounded by a most simple environment already opening ICD as a deexcitation channel. As a consequence, we find a dramatically enhanced low energy electron yield. The results suggest that ICD may have a significant influence on cell survival after exposure to ionizing radiation.

  3. Scenario analysis of energy-based low-carbon development in China.

    PubMed

    Zhou, Yun; Hao, Fanghua; Meng, Wei; Fu, Jiafeng

    2014-08-01

    China's increasing energy consumption and coal-dominant energy structure have contributed not only to severe environmental pollution, but also to global climate change. This article begins with a brief review of China's primary energy use and associated environmental problems and health risks. To analyze the potential of China's transition to low-carbon development, three scenarios are constructed to simulate energy demand and CO₂ emission trends in China up to 2050 by using the Long-range Energy Alternatives Planning System (LEAP) model. Simulation results show that with the assumption of an average annual Gross Domestic Product (GDP) growth rate of 6.45%, total primary energy demand is expected to increase by 63.4%, 48.8% and 12.2% under the Business as Usual (BaU), Carbon Reduction (CR) and Integrated Low Carbon Economy (ILCE) scenarios in 2050 from the 2009 levels. Total energy-related CO₂ emissions will increase from 6.7 billiontons in 2009 to 9.5, 11, 11.6 and 11.2 billiontons; 8.2, 9.2, 9.6 and 9 billiontons; 7.1, 7.4, 7.2 and 6.4 billiontons in 2020, 2030, 2040 and 2050 under the BaU, CR and ILCE scenarios, respectively. Total CO₂ emission will drop by 19.6% and 42.9% under the CR and ILCE scenarios in 2050, compared with the BaU scenario. To realize a substantial cut in energy consumption and carbon emissions, China needs to make a long-term low-carbon development strategy targeting further improvement of energy efficiency, optimization of energy structure, deployment of clean coal technology and use of market-based economic instruments like energy/carbon taxation. PMID:25108719

  4. Scenario analysis of energy-based low-carbon development in China.

    PubMed

    Zhou, Yun; Hao, Fanghua; Meng, Wei; Fu, Jiafeng

    2014-08-01

    China's increasing energy consumption and coal-dominant energy structure have contributed not only to severe environmental pollution, but also to global climate change. This article begins with a brief review of China's primary energy use and associated environmental problems and health risks. To analyze the potential of China's transition to low-carbon development, three scenarios are constructed to simulate energy demand and CO₂ emission trends in China up to 2050 by using the Long-range Energy Alternatives Planning System (LEAP) model. Simulation results show that with the assumption of an average annual Gross Domestic Product (GDP) growth rate of 6.45%, total primary energy demand is expected to increase by 63.4%, 48.8% and 12.2% under the Business as Usual (BaU), Carbon Reduction (CR) and Integrated Low Carbon Economy (ILCE) scenarios in 2050 from the 2009 levels. Total energy-related CO₂ emissions will increase from 6.7 billiontons in 2009 to 9.5, 11, 11.6 and 11.2 billiontons; 8.2, 9.2, 9.6 and 9 billiontons; 7.1, 7.4, 7.2 and 6.4 billiontons in 2020, 2030, 2040 and 2050 under the BaU, CR and ILCE scenarios, respectively. Total CO₂ emission will drop by 19.6% and 42.9% under the CR and ILCE scenarios in 2050, compared with the BaU scenario. To realize a substantial cut in energy consumption and carbon emissions, China needs to make a long-term low-carbon development strategy targeting further improvement of energy efficiency, optimization of energy structure, deployment of clean coal technology and use of market-based economic instruments like energy/carbon taxation.

  5. A study of low-dimensional quaternary mixed-transition metal chalcogenides

    NASA Astrophysics Data System (ADS)

    Oledzka, Magdalena Agata

    New quaternary alkali metal mixed-transition metal sulfides: ACuMSsb2 (A = K, Rb, Cs; M = Mn, Fe, Co) and KCosb{2-x}Cusb{x}Ssb2 (0.5 ≤ x ≤ 1.5) were prepared by CSsb2/Nsb2 sulfurization of a mixture of oxide or sulfide and carbonate precursors of the corresponding metals. All of the phases form in the tetragonal ThCrsb2Sisb2-type structure in space group I4/mmm. The ACoCuSsb2 phases are semiconducting, with room temperature resistivities rhosbRT˜ 10sp{-2}Omega {*}cm;\\ KCosb{0.5}CUsb{1.5}Ssb2 is metallic with a metal-to-nonmetal transition at ˜120 K. Seebeck measurements indicate that the majority of charge carriers are holes. The temperature dependence of magnetic susceptibility shows an anomalous transition to the ferromagnetic state in the ACoCuSsb2 phases. The electrical and magnetic properties of the new quaternary phases are compared to those of ternary ACosb2Ssb2 (A = K, Rb, Cs). The quaternary sulfides ACuFeSsb2 show semiconducting behavior. Magnetic susceptibility data indicate the presence of localized magnetic moment arising from the di- and trivalent iron ions. The semiconducting properties observed in this system are in contrast to the metallic behavior predicted by theoretical calculations. Investigations of the electrical properties of the sulfides ACuMnSsb2 revealed semiconducting behavior with a broad anomaly at ≈70 K. In the temperature range 100-300 K, the molar magnetic susceptibility of all the samples shows a weak maximum consistent with localized antiferromagnetic exchange of isolated two-dimensional manganese cluster nets. The divergence of the FC and ZFC molar susceptibilities at low temperatures, for all the samples, suggests spin-glass-type behavior with a well defined freezing temperature of ≈35 K. Single phase polycrystalline quaternary selenides ACuMnSesb2 (A = K, Rb, Cs) were prepared for the first time by the reduction of the mixture containing corresponding alkali metal carbonates, copper oxide, manganese and selenium

  6. Energy Savings of Low-E Storm Windows and Panels across US Climate Zones

    SciTech Connect

    Culp, Thomas D.; Cort, Katherine A.

    2015-10-01

    This report builds off of previous modeling work related to low-e storm windows used to create a "Database of U.S. Climate-Based Analysis for Low-E Storm Windows." This work updates similar studies using new fuel costs and examining the separate contributions of reduced air leakage and reduced coefficients of overall heat transfer and solar heat gain. In this report we examine the energy savings and cost effectiveness of low-E storm windows in residential homes across a broad range of U.S. climates, excluding the impact from infiltration reductions, which tend to vary using the National Energy Audit Tool (NEAT) and RESFEN model calculations. This report includes a summary of the results, NEAT and RESFEN background, methodology, and input assumptions, and an appendix with detailed results and assumptions by climate zone.

  7. Thermomodulation spectra of high-energy interband transitions in Cu, Pd, Ag, Pt, and Au

    SciTech Connect

    Olson, C.G.; Lynch, D.W.; Rosei, R.

    1980-07-15

    Thermotransmission and thermoreflectance spectra were obtained for Cu, Pd, Ag, Pt, and Au in the 10 --30 eV spectral region. Structures due to transitions from the Fermi level to high-density bands 15 eV above the Fermi level were identified in Pt. All metals showed structures arising from interband transitions between the d bands and the same flat bands, 15--20 eV above the Fermi energy. Attempts to fit to interband critical points in Au revealed over 40 possible critical points in the region of these structures, most of them near the Brillouin-zone centers. Systematic trends in the series of metals make the qualitative identification of the structures more secure, and no energy shifts of calculated energy bands are required. The observed widths of structures are sometimes much narrower than the widths of free-electron-like bands at comparable energies.

  8. Large conversion of energy in dielectric elastomers by electromechanical phase transition

    NASA Astrophysics Data System (ADS)

    Lu, Tong-Qing; Suo, Zhi-Gang

    2012-08-01

    When air is pumped in, a tubular balloon initially inflates slightly and homogeneously. A short section of the balloon then forms a bulge, which coexists with the unbulged section of the balloon. As more air is pumped in, the bulged section elongates at the expense of the unbulged section, until the entire balloon is bulged. The phenomenon is analogous to the liquid-to-vapor phase transition. Here we study the bulging transition in a dielectric elastomer tube as air is pumped into the balloon and a voltage is applied through the thickness of the membrane. We formulate the condition for coexistent budged and unbulged sections, and identify allowable states set by electrical breakdown and mechanical rupture. We find that the bulging transition dramatically amplifies electromechanical energy conversion. Energy converted in an electromechanical cycle consisting of unbulged and bulged states is thousands of times that in an electromechanical cycle consisting of only unbulged states.

  9. STABILITY IN BCC TRANSITION METALS: MADELUNG AND BAND-ENERGY EFFECTS DUE TO ALLOYING

    SciTech Connect

    Landa, A; Soderlind, P; Ruban, A; Peil, O; Vitos, L

    2009-08-28

    The phase stability of the bcc Group VB (V, Nb, and Ta) transition metals is explored by first-principles electronic-structure calculations. Alloying with a small amount of a neighboring metal can either stabilize or destabilize the bcc phase. This counterintuitive behavior is explained by competing mechanisms that dominate depending on particular dopand. We show that band-structure effects dictate stability when a particular Group VB metal is alloyed with its nearest neighbors within the same d-transition series. In this case, the neighbor with less (to the left) and more (to the right) d electrons, destabilize and stabilize bcc, respectively. When alloying with neighbors of different d-transition series, electrostatic Madelung energy dominates over the band energy and always stabilizes the bcc phase.

  10. Low-Energy Monte Carlo and W-Values

    NASA Astrophysics Data System (ADS)

    Grosswendt, B.

    Electrons in the low-energy range of about 1 keV or less play an important role in many fields of radiation research for two reasons: firstly, they are created in large numbers during the passage of all kinds of ionizing radiation through matter, and secondly, they have a linear energy transfer comparable to that of low-energy protons and a-particles, and accordingly they are responsible for the greater part of radiation damage observable in any material. A detailed understanding of the action of low-energy electrons in matter therefore is required in many contexts. In the fields of dosimetry, for example, the determination of the absorbed dose in water or the air kerma is great practical importance, but in most experiments only the amount of ionization produced by secondary electrons within the sensitive volume of a dosimeter can be measured. The results of ionization measurements therefore must converted to quantities based on energy absorption or energy transfer, either by calibration or numerically using an appropriate conversion factor. The most frequently used conversion factor is the so-called W-value, which is the mean energy required to produce an ion pair upon complete slowing down of a charged particle. Its relation to the primary particle kinetic energy T, and to the mean n umber N i of ionizations produced (ionization yield), is given by

  11. Electron cooling for low-energy RHIC program

    SciTech Connect

    Fedotov, A.; Ben-Zvi, I.; Chang, X.; Kayran, D.; Litvinenko, V.N.; Pendzick, A.; Satogata, T.

    2009-08-31

    Electron cooling was proposed to increase luminosity of the RHIC collider for heavy ion beam energies below 10 GeV/nucleon. Providing collisions at such energies, termed RHIC 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of critical point on the QCD phase diagram. The electron cooling system should deliver electron beam of required good quality over energies of 0.9-5 MeV. Several approaches to provide such cooling were considered. The baseline approach was chosen and design work started. Here we describe the main features of the cooling system and its expected performance. We have started design work on a low-energy RHIC electron cooler which will operate with kinetic electron energy range 0.86-2.8 (4.9) MeV. Several approaches to an electron cooling system in this energy range are being investigated. At present, our preferred scheme is to transfer the Fermilab Pelletron to BNL after Tevatron shutdown, and to use it for DC non-magnetized cooling in RHIC. Such electron cooling system can significantly increase RHIC luminosities at low-energy operation.

  12. Low Light Adaptation: Energy Transfer Processes in Different Types of Light Harvesting Complexes from Rhodopseudomonas palustris

    PubMed Central

    Moulisová, Vladimíra; Luer, Larry; Hoseinkhani, Sajjad; Brotosudarmo, Tatas H.P.; Collins, Aaron M.; Lanzani, Guglielmo; Blankenship, Robert E.; Cogdell, Richard J.

    2009-01-01

    Abstract Energy transfer processes in photosynthetic light harvesting 2 (LH2) complexes isolated from purple bacterium Rhodopseudomonas palustris grown at different light intensities were studied by ground state and transient absorption spectroscopy. The decomposition of ground state absorption spectra shows contributions from B800 and B850 bacteriochlorophyll (BChl) a rings, the latter component splitting into a low energy and a high energy band in samples grown under low light (LL) conditions. A spectral analysis reveals strong inhomogeneity of the B850 excitons in the LL samples that is well reproduced by an exponential-type distribution. Transient spectra show a bleach of both the low energy and high energy bands, together with the respective blue-shifted exciton-to-biexciton transitions. The different spectral evolutions were analyzed by a global fitting procedure. Energy transfer from B800 to B850 occurs in a mono-exponential process and the rate of this process is only slightly reduced in LL compared to high light samples. In LL samples, spectral relaxation of the B850 exciton follows strongly nonexponential kinetics that can be described by a reduction of the bleach of the high energy excitonic component and a red-shift of the low energetic one. We explain these spectral changes by picosecond exciton relaxation caused by a small coupling parameter of the excitonic splitting of the BChl a molecules to the surrounding bath. The splitting of exciton energy into two excitonic bands in LL complex is most probably caused by heterogenous composition of LH2 apoproteins that gives some of the BChls in the B850 ring B820-like site energies, and causes a disorder in LH2 structure. PMID:19948132

  13. Low light adaptation: energy transfer processes in different types of light harvesting complexes from Rhodopseudomonas palustris.

    PubMed

    Moulisová, Vladimíra; Luer, Larry; Hoseinkhani, Sajjad; Brotosudarmo, Tatas H P; Collins, Aaron M; Lanzani, Guglielmo; Blankenship, Robert E; Cogdell, Richard J

    2009-12-01

    Energy transfer processes in photosynthetic light harvesting 2 (LH2) complexes isolated from purple bacterium Rhodopseudomonas palustris grown at different light intensities were studied by ground state and transient absorption spectroscopy. The decomposition of ground state absorption spectra shows contributions from B800 and B850 bacteriochlorophyll (BChl) a rings, the latter component splitting into a low energy and a high energy band in samples grown under low light (LL) conditions. A spectral analysis reveals strong inhomogeneity of the B850 excitons in the LL samples that is well reproduced by an exponential-type distribution. Transient spectra show a bleach of both the low energy and high energy bands, together with the respective blue-shifted exciton-to-biexciton transitions. The different spectral evolutions were analyzed by a global fitting procedure. Energy transfer from B800 to B850 occurs in a mono-exponential process and the rate of this process is only slightly reduced in LL compared to high light samples. In LL samples, spectral relaxation of the B850 exciton follows strongly nonexponential kinetics that can be described by a reduction of the bleach of the high energy excitonic component and a red-shift of the low energetic one. We explain these spectral changes by picosecond exciton relaxation caused by a small coupling parameter of the excitonic splitting of the BChl a molecules to the surrounding bath. The splitting of exciton energy into two excitonic bands in LL complex is most probably caused by heterogenous composition of LH2 apoproteins that gives some of the BChls in the B850 ring B820-like site energies, and causes a disorder in LH2 structure.

  14. Theoretical equilibrium geometry, vibrational frequencies and the first electronic transition energy of HCC

    NASA Astrophysics Data System (ADS)

    Fogarasi, Géza; Boggs, James E.; Pulay, Péter

    Ab initio calculations with the 6-311 G** basis set and all single and double excitations in the CI treatment have been carried out to determine the structure of the HCC radical. The theoretical geometry of R(CC) = 1·209, r(CH) = 1·067 Å (or 1·205 and 1·063, respectively, if corrected for residual errors) is in excellent accordance with the experimental rotational constant. The calculated harmonic vibrational frequencies are v1 ⋍ 3450, v2 ⋍ 540 and v3 ⋍ 2040 cm-1. An extremely low energy around 2000 cm-1 is obtained for the first electronic transition A2II ← X 2∑. Results for the excited state are also given. The theoretical vibrational frequencies, with all possible errors taken into account, are inconsistent with the accepted interpretations of the few experimental results. It is shown, however, that a complete reinterpretation of the spectroscopic observations is possible, by which the present calculations fit with the recent gas phase infrared laser spectroscopic data but remain in definite contradiction with the infrared matrix results.

  15. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, James R.; Reich, Morris; Ludewig, Hans; Todosow, Michael

    1999-02-09

    A particle accelerator (12) generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target (14) is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target (14) produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer (44) and a neutron filter (42) are also used for preferentially degrading the secondary particles into a lower energy range if desired.

  16. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, J.R.; Reich, M.; Ludewig, H.; Todosow, M.

    1999-02-09

    A particle accelerator generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer and a neutron filter are also used for preferentially degrading the secondary particles into a lower energy range if desired. 18 figs.

  17. Milagro: A low energy threshold extensive air shower array

    SciTech Connect

    Sinnis, C.

    1994-12-31

    Observations of high-energy gamma rays from astronomical sources have revolutionized our view of the cosmos. Gamma rays with energies up to {approximately}10 GeV can be observed directly with space-based instruments. Above 100 GeV the low flux of gamma rays requires one to utilize ground-based instruments. Milagro is a new type of gamma-ray detector based on water Cerenkov technology. This new design will enable to continuously observe the entire overhead sky, and be sensitive to cosmic rays with energies above {approximately}250 GeV. These attributes make Milagro an ideal detector for the study of high-energy transient phenomenon.

  18. Energy transfer enhancement by oxygen perturbation of spin-forbidden electronic transitions in aromatic systems

    NASA Astrophysics Data System (ADS)

    Monguzzi, A.; Tubino, R.; Salamone, M. M.; Meinardi, F.

    2010-09-01

    Triplet-triplet energy transfer in multicomponent organic systems is usually entirely ascribed to a Dexter-type mechanism involving only short-range donor/acceptor interactions. We demonstrate that the presence of molecular oxygen introduces a perturbation to the electronic structure of one of the involved moieties which can induce a large increase in the spin-forbidden transition oscillator strength so that the otherwise negligible Förster contribution dominates the overall energy transfer rate.

  19. Surface energy from order parameter profile: At the QCD phase transition

    NASA Technical Reports Server (NTRS)

    Frei, Z.; Patkos, A.

    1989-01-01

    The order parameter profile between coexisting confined and plasma regions at the quantum chromodynamic (QCD) phase transition is constructed. The dimensionless combination of the surface energy (Sigma) and the correlation length (Zeta) is estimated to be Sigma Zeta 3 approximately equals 0.8.

  20. Scintillating screens sensitivity and resolution studies for low energy, low intensity beam diagnostics.

    PubMed

    Harasimowicz, Janusz; Cosentino, Luigi; Finocchiaro, Paolo; Pappalardo, Alfio; Welsch, Carsten P

    2010-10-01

    In order to investigate the limits of scintillating screens for beam profile monitoring in the ultra-low energy, ultra-low intensity regime, CsI:Tl, YAG:Ce, and a Tb glass-based scintillating fiber optic plate (SFOP) were tested. The screens response to 200 and 50 keV proton beams with intensities ranging from a few picoampere down to the subfemtoampere region was examined. In the following paper, the sensitivity and resolution studies are presented in detail for CsI:Tl and the SFOP, the two most sensitive screens. In addition, a possible use of scintillators for ultra-low energy antiproton beam monitoring is discussed.

  1. Determination of electron bunch shape using transition radiation and phase-energy measurements

    SciTech Connect

    Crosson, E.R.; Berryman, K.W.; Richman, B.A.

    1995-12-31

    We present data comparing microbunch temporal information obtained from electron beam phase-energy measurements with that obtained from transition radiation auto-correlation measurements. The data was taken to resolve some of the ambiguities in previous transition radiation results. By measuring the energy spectrum of the electron beam as a function of its phase relative to the accelerating field, phase-energy information was extracted. This data was analyzed using tomographic techniques to reconstruct the phase-space distribution assuming an electron energy dependence of E({var_phi}) = E{sub o} + E{sub acc}cos({var_phi}), where E{sub o} is the energy of an electron entering the field, E{sub acc} is the peak energy gain, and {var_phi} is the phase between the crest of the RF wave and an electron. Temporal information about the beam was obtained from the phase space distribution by taking the one dimensional projection along the time axis. We discuss the use of this technique to verify other transition radiation analysis methods.

  2. Statistical simulation of internal energy exchange in shock waves using explicit transition probabilities

    NASA Astrophysics Data System (ADS)

    Torres, Erik; Magin, Thierry

    2012-11-01

    A statistical model originally developed for electronic-translational energy transfer in atoms having multiple electronic states (Anderson et al, RGD15, 1986) is applied to the study of internal energy exchange in a polyatomic gas. The model is well-suited for gas kinetic simulations, because it provides an explicit expression for the transition probabilities between internal energy levels. All molecules possessing a given internal energy level are treated as a separate chemical species and all collisions involving exchange of internal energy thus become pseudo-chemical reactions. Post-collision energy levels of the two partners are determined by conserving the total energy of the collision pair and taking into account detailed balance. In the present work, DSMC simulations of relaxation in a stationary gas are performed and compared to those obtained by Anderson et al. Additionally, we apply the model to the simulation of rotational relaxation behind a normal shock wave.

  3. Anderson transition in low-dimensional disordered systems driven by long-range nonrandom hopping.

    PubMed

    Rodríguez, A; Malyshev, V A; Sierra, G; Martín-Delgado, M A; Rodríguez-Laguna, J; Domínguez-Adame, F

    2003-01-17

    The single-parameter scaling hypothesis predicts the absence of delocalized states for noninteracting quasiparticles in low-dimensional disordered systems. We show analytically, using a supersymmetric method combined with a renormalization group analysis, as well as numerically that extended states may occur in the one- and two-dimensional Anderson model with a nonrandom hopping falling off as some power of the distance between sites. The different size scaling of the bare level spacing and the renormalized magnitude of the disorder seen by the quasiparticles finally results in the delocalization of states at one of the band edges of the quasiparticle energy spectrum.

  4. First-order transition in confined water between high-density liquid and low-density amorphous phases.

    PubMed

    Koga, K; Tanaka, H; Zeng, X C

    2000-11-30

    Supercooled water and amorphous ice have a rich metastable phase behaviour. In addition to transitions between high- and low-density amorphous solids, and between high- and low-density liquids, a fragile-to-strong liquid transition has recently been proposed, and supported by evidence from the behaviour of deeply supercooled bilayer water confined in hydrophilic slit pores. Here we report evidence from molecular dynamics simulations for another type of first-order phase transition--a liquid-to-bilayer amorphous transition--above the freezing temperature of bulk water at atmospheric pressure. This transition occurs only when water is confined in a hydrophobic slit pore with a width of less than one nanometre. On cooling, the confined water, which has an imperfect random hydrogen-bonded network, transforms into a bilayer amorphous phase with a perfect network (owing to the formation of various hydrogen-bonded polygons) but no long-range order. The transition shares some characteristics with those observed in tetrahedrally coordinated substances such as liquid silicon, liquid carbon and liquid phosphorus. PMID:11117739

  5. Development of decay energy spectroscopy using low temperature detectors.

    PubMed

    Jang, Y S; Kim, G B; Kim, K J; Kim, M S; Lee, H J; Lee, J S; Lee, K B; Lee, M K; Lee, S J; Ri, H C; Yoon, W S; Yuryev, Y N; Kim, Y H

    2012-09-01

    We have developed a high-resolution detection technique for measuring the energy and activity of alpha decay events using low-temperature detectors. A small amount of source material containing alpha-emitting radionuclides was enclosed in a 4π metal absorber. The energy of the alpha particles as well as that of the recoiled nuclides, low-energy electrons, and low-energy x-rays and γ-rays was converted into thermal energy of the gold absorber. A metallic magnetic calorimeter serving as a fast and sensitive thermometer was thermally attached to the metal absorber. In the present report, experimental demonstrations of Q spectroscopy were made with a new meander-type magnetic calorimeter. The thermal connection between the temperature sensor and the absorber was established with annealed gold wires. Each alpha decay event in the absorber resulted in a temperature increase of the absorber and the temperature sensor. Using the spectrum measured for a drop of (226)Ra solution in a 4π gold absorber, all of the alpha emitters in the sample were identified with a demonstration of good detector linearity. The resolution of the (226)Ra spectrum showed a 3.3 keV FWHM at its Q value together with an expected gamma escape peak at the energy shifted by its γ-ray energy.

  6. Transition from a matter-dominated era to a dark energy universe

    SciTech Connect

    Nojiri, Shin'ichi; Odintsov, Sergei D.; Stefancic, Hrvoje

    2006-10-15

    We develop a general program of the unification of a matter-dominated era with an acceleration epoch for scalar-tensor theory or a dark fluid. The general reconstruction of the scalar-tensor theory is fulfilled. The explicit form of the scalar potential for which the theory admits a matter-dominated era, a transition to an acceleration, and an (asymptotically de Sitter) acceleration epoch consistent with Wilkinson Microwave Anisotropy Probe data is found. The interrelation of the epochs of deceleration-acceleration transition and matter dominance-dark energy transition for dark fluids with a general equation of state (EOS) is investigated. We give several examples of such models with explicit EOS (using redshift parametrization) where matter-dark energy domination transition may precede the deceleration-acceleration transition. As a by-product, the reconstruction scheme is applied to scalar-tensor theory to define the scalar potentials which may produce the dark matter effect. The obtained modification of Newton potential may explain the rotation curves of galaxies.

  7. Low-Energy Ions from Laser-Cooled Atoms

    NASA Astrophysics Data System (ADS)

    Shayeganrad, G.; Fioretti, A.; Guerri, I.; Tantussi, F.; Ciampini, D.; Allegrini, M.; Viteau, M.; Fuso, F.

    2016-05-01

    We report the features of an ion source based on two-color photoionization of a laser-cooled cesium beam outsourced from a pyramidal magneto-optical trap. The ion source operates in continuous or pulsed mode. At acceleration voltages below 300 V, it delivers some ten ions per bunch with a relative energy spread Δ Urms/U ≃0.032 , as measured through the retarding field-energy-analyzer approach. Space-charge effects are negligible thanks to the low ion density attained in the interaction volume. The performances of the ion beam in a configuration using focused laser beams are extrapolated on the basis of the experimental results. Calculations demonstrate that our low-energy and low-current ion beam can be attractive for the development of emerging technologies requiring the delivery of a small amount of charge, down to the single-ion level and its eventual focusing in the 10-nm range.

  8. HIGH POWER OPERATIONS AT THE LOW ENERGY DEMONSTRATION ACCELERATOR (LEDA)

    SciTech Connect

    M. DURAN; V. R. HARRIS

    2001-01-01

    Recently, the Low-Energy Demonstration Accelerator (LEDA) portion of the Accelerator Production of Tritium (APT) project reached its 100-mA, 8-hr continuous wave (CW) beam operation milestone. The LEDA accelerator is a prototype of the low-energy front-end of the linear accelerator (linac) that would have been used in an APT plant. LEDA consists of a 75-keV proton injector, 6.7-MeV, 350-MHz CW radio-frequency quadrupole (RFQ) with associated high-power and low-level RF systems, a short high-energy beam transport (HEBT) and high-power (670-kW CW) beam dump. Details of the LEDA design features will be discussed along with the operational health physics experiences that occurred during the LEDA commissioning phase.

  9. Optimal electron, phonon, and magnetic characteristics for low energy thermally induced magnetization switching

    SciTech Connect

    Atxitia, U.; Ostler, T. A.; Chantrell, R. W.; Chubykalo-Fesenko, O.

    2015-11-09

    Using large-scale computer simulations, we thoroughly study the minimum energy required to thermally induced magnetization switching (TIMS) after the application of a femtosecond heat pulse in transition metal-rare earth ferrimagnetic alloys. We find that for an energy efficient TIMS, a low ferrimagnetic net magnetization with a strong temperature dependence is the relevant factor for the magnetic system. For the lattice and electron systems, the key physics for efficient TIMS is a large electron-phonon relaxation time. Importantly, we show that as the cooling time of the heated electrons is increased, the minimum power required to produce TIMS can be reduced by an order of magnitude. Our results show the way to low power TIMS by appropriate engineering of magnetic heterostructures.

  10. Optimal electron, phonon, and magnetic characteristics for low energy thermally induced magnetization switching

    NASA Astrophysics Data System (ADS)

    Atxitia, U.; Ostler, T. A.; Chantrell, R. W.; Chubykalo-Fesenko, O.

    2015-11-01

    Using large-scale computer simulations, we thoroughly study the minimum energy required to thermally induced magnetization switching (TIMS) after the application of a femtosecond heat pulse in transition metal-rare earth ferrimagnetic alloys. We find that for an energy efficient TIMS, a low ferrimagnetic net magnetization with a strong temperature dependence is the relevant factor for the magnetic system. For the lattice and electron systems, the key physics for efficient TIMS is a large electron-phonon relaxation time. Importantly, we show that as the cooling time of the heated electrons is increased, the minimum power required to produce TIMS can be reduced by an order of magnitude. Our results show the way to low power TIMS by appropriate engineering of magnetic heterostructures.

  11. A study of low-energy type II supernovae

    NASA Astrophysics Data System (ADS)

    Lisakov, Sergey M.; Dessart, Luc; Hillier, D. John; Waldman, Roni; Livne, Eli

    2015-08-01

    All stars with an initial mass greater than 8Msun, but not massive enough to encounter the pair-production instability, eventually form a degenerate core and collapse to form a compact object, either a neutron star or a black hole.At the lower mass end, these massive stars die as red-supergiant stars and give rise to Type II supernovae (SNe). The diversity of observed properties of SNe II suggests a range of progenitor mass, radii, but also explosion energy.We have performed a large grid simulations designed to cover this range of progenitor and explosion properties. Using MESA STAR, we compute a set of massive star models (12-30Msun) from the main sequence until core collapse. We then generate explosions with V1D to produce ejecta with a range of explosion energies and yields. Finally, all ejecta are evolved with CMFGEN to generate multi-band light curves and spectra.In this poster, we focus our attention on the properties of low-energy explosions that give rise to low-luminosity Type II Plateau (II-P) SNe. In particular, we present a detailed study of SN 2008bk, but also include other notorious low-energy SNe II-P like 2005cs, emphasising their non-standard properties by comparing to models that match well events like SN 1999em. Such low-energy explosions, characterised by low ejecta expansion rates, are more suitable for reliable spectral line identifications.Based on our models, we discuss the distinct signatures of low-energy explosions in lower and higher mass models. One important goal is to identify whether there is a progenitor-mass bias leading to such events.

  12. Low-Energy Dynamics in Ultradegenerate QCD Matter

    SciTech Connect

    Schaefer, Thomas; Schwenzer, Kai

    2006-09-01

    We study the low-energy behavior of QCD Green functions in the limit that the baryon chemical potential is much larger than the QCD scale parameter {lambda}{sub QCD}. We show that there is a systematic low-energy expansion in powers of ({omega}/m){sup 1/3}, where {omega} is the energy and m is the screening scale. This expansion is valid even if the effective quark-gluon coupling g is not small. The expansion is purely perturbative in the magnetic regime vertical bar k(vector sign) vertical bar >>k{sub 0}. If the external momenta and energies satisfy vertical bar k(vector sign) vertical bar ={approx}k{sub 0}, planar, Abelian ladder diagrams involving the full quark propagator have to be resummed but the corresponding Dyson-Schwinger equations are closed.

  13. Semiconductor detector performance for low-energy x-rays

    SciTech Connect

    Jaklevic, J.M.; Walton, J.T.; McMurray, R.E. Jr.; Madden, N.W.; Goulding, F.S.

    1987-06-01

    Factors that limit the capabilities of semiconductor detectors at photon energies below 5 keV include energy resolution, detector efficiency, and detector-related continuum background. These properties can be controlled to a certain extent by optimal detector design and fabrication techniques. We describe measurements on the low-energy response of Si(Li) detectors obtained using a tunable, low-energy monochromatic source. Window thicknesses have been measured for a number of devices using different materials for the entry contact. The interpretation of these results in terms of existing detector window models is discussed. Results obtained using a new contact structure demonstrate that a dramatic reduction in window-related absorption in Si(Li) detectors can be achieved.

  14. Simulation study of free-energy barriers in the wetting transition of an oily fluid on a rough surface with reentrant geometry.

    PubMed

    Savoy, Elizabeth S; Escobedo, Fernando A

    2012-11-20

    When in contact with a rough solid surface, fluids with low surface tension, such as oils and alkanes, have their lowest free energy in the fully wetted state. For applications where nonwetting by these phillic fluids is desired, some barrier must be introduced to maintain the nonwetted composite state. One way to create this free-energy barrier is to fabricate roughness with reentrant geometry, but the question remains as to whether the free-energy barrier is sufficiently high to prevent wetting. Our goal is to quantify the free-energy landscape for the wetting transition of an oily fluid on a surface of nails and identify significant surface features and conditions that maximize the wetting free-energy barrier (ΔGfwd*). This is a departure from most work on wetting, which focuses on the equilibrium composite and wetted states. We use boxed molecular dynamics (BXD) (Glowacki, D. R.; Paci, E.; Shalashilin, D. V. J. Phys. Chem. B2009, 113, 16603-16611) with a modified control scheme to evaluate both the thermodynamics and kinetics of the transition over a range of surface affinities (chemistry). We find that the reentrant geometry of the nails does create a free-energy barrier to transition for phillic chemistry whereas a corresponding system on straight posts wets spontaneously and, that doubling the nail height more than doubles ΔGfwd*. For neutral to phillic chemistry, the dewetting free-energy barrier is at least an order of magnitude higher than that for wetting, indicating an essentially irreversible wetting transition. Transition rates from BXD simulations and the associated trends agree well with those in our previous study that used forward flux sampling to compute transition rates for similar systems.

  15. Crossflow transition at Mach 6 on a cone at low angles of attack

    NASA Astrophysics Data System (ADS)

    Henderson, Ryan O.

    Experiments on a sharp 7-degree cone at low angles of attack were conducted at Mach 6 to understand the stationary and traveling modes of crossflow disturbances, the interaction between them, and the development of other instabilities that can lead to transition. Using the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT), pressure and temperature measurements were collected to better describe crossflow characteristics. Noisy and quiet flow conditions were compared to understand crossflow development. Temperature Sensitive Paint (TSP) was used to measure the global surface temperatures on the model. Schmidt-Boelter (SB) gauges were used to convert the surface temperatures to heat transfer. The global heat transfer then allowed the stationary crossflow to be visualized and quantified in terms of heat flux. Integrating heat fluxes azimuthally, the amplitudes of the stationary crossflow vortices were compared. against the amplitudes of the traveling waves. PCB 132A31 and Kulite XCQ-062-15A transducers were used to measure pressure fluctuations over a broad range of frequencies. The traveling crossflow instability, the second-mode instability, and possibly the secondary-instability of the stationary crossflow mode were found at certain tunnel conditions. A grouping of Kulites was used to determine traveling wave speed and direction. Roughness elements were added to the model to excite discrete stationary vortices. The roughness elements provided a method to alter the strength of the stationary vortices. This technique allowed traveling-mode amplitudes to be compared to varying stationary-mode amplitudes.

  16. Low molecular weight fucoidan ameliorates diabetic nephropathy via inhibiting epithelial-mesenchymal transition and fibrotic processes

    PubMed Central

    Chen, Jihui; Cui, Wentong; Zhang, Quanbin; Jia, Yingli; Sun, Yi; Weng, Lin; luo, Dali; Zhou, Hong; Yang, Baoxue

    2015-01-01

    Diabetic nephropathy (DN) is one of the most serious microvascular complications of diabetes and may lead to end-stage renal disease (ESRD) and chronic renal failure. The aim of this study was to determine whether low-molecular-weight fucoidan (LMWF) can reduce harmful transforming growth factor-β (TGF-β)-mediated renal fibrosis in DN using in vitro and in vivo experimental models. The experimental results showed that LMWF significantly reversed TGF-β1-induced epithelial-mesenchymal transition and dose-dependently inhibited accumulation of extracellular matrix proteins, including connective tissue growth factor and fibronectin. It was found that LMWF significantly reduced blood urea nitrogen and blood creatinine in both type 1 and type 2 diabetic rat models. H&E, PAS and Masson’s trichrome staining of kidney tissue showed LMWF significantly reduced renal interstitial fibrosis. Treatment with LMWF significantly increased E-cadherin expression and reduced α-SMA, CTGF and fibronectin expression in both type 1 and type 2 diabetic models. LMWF also decreased the phosphorylation of Akt, ERK1/2, p38 and Smad3 in vitro and in vivo. These data suggest that LMWF may protect kidney from dysfunction and fibrogenesis by inhibiting TGF-β pathway and have the potential benefit to slow down the progression of DN. PMID:26550455

  17. Layering effects on low frequency modes in n-layered MX2 transition metal dichalcogenides.

    PubMed

    Cammarata, Antonio; Polcar, Tomas

    2016-02-14

    n-Layered (n = 2, 3, 4) MX2 transition metal dichalcogenides (M = Mo, W; X = S, Se, Te) have been studied using DFT techniques. Long-range van der Waals forces have been modeled using the Grimme correction to capture interlayer interactions. We study the dynamic and electronic dependence of atomic displacement on the number of layers. We find that the displacement patterns mainly affected by a change in the layer number are low-frequency modes at Γ and A k-points; such modes are connected with the intrinsic tribological response. We disentangle electro-phonon coupling by combining orbital polarization, covalency and cophonicity analysis with phonon band calculations. We find that the frequency dependence on the number of layers and the atomic type has a non-trivial relation with the electronic charge distribution in the interlayer region. We show that the interlayer electronic density can be adjusted by appropriately tuning M-X cophonicity, acting as a knob to control vibrational frequencies, hence the intrinsic frictional response. The present results can be exploited to study the electro-phonon coupling effects in TMD-based materials beyond tribological applications. PMID:26806673

  18. Head-up transition behavior of pilots during simulated low-visibility approaches

    NASA Technical Reports Server (NTRS)

    Haines, R. F.

    1980-01-01

    Each of 13 commercial pilots from four airlines flew a total of 108 manual flight director approaches in a moving base simulation of a medium-sized turbojet (95,000 lb gross weight) which had a day and night Redifon external scene. Three levels of runway visual range (RVR) (1,600; 2,400; and greater than 8,000 ft), three wind-shear profiles, nine ceiling heights, and continuous and intermittent visibility after initial breakout were tested. The results indicated that: (1) mean decision time ranged from 2 to 4.6 sec for ceilings under 380 ft across the three RVR conditions; (2) mean vertical distance traveled during the visual-cue assessment period was a relatively constant proportion below the existing ceiling; (3) a significant three way interaction in mean decision time between wind shear, day-night, and ceiling RVR variables occurred; (4) mean number of head-up transitions to VFR conditions after breakout ranged from 4.6 to 13.4 and increased as a function of ceiling and severity of wind shear; the typical duration of fixation out the window was 1.5 sec; and (5) subjective pilot ratings of controllability and precision of control as well as amount of skill, attention, or effort required to make the landing were influenced significantly by the wind shear, night conditions, and low breakout ceiling conditions.

  19. A Framework for Supporting Organizational Transition Processes Towards Sustainable Energy Systems

    NASA Astrophysics Data System (ADS)

    Buch, Rajesh

    Economic development over the last century has driven a tripling of the world's population, a twenty-fold increase in fossil fuel consumption, and a tripling of traditional biomass consumption. The associated broad income and wealth inequities are retaining over 2 billion people in poverty. Adding to this, fossil fuel combustion is impacting the environment across spatial and temporal scales and the cost of energy is outpacing all other variable costs for most industries. With 60% of world energy delivered in 2008 consumed by the commercial and industrial sector, the fragmented and disparate energy-related decision making within organizations are largely responsible for the inefficient and impacting use of energy resources. The global transition towards sustainable development will require the collective efforts of national, regional, and local governments, institutions, the private sector, and a well-informed public. The leadership role in this transition could be provided by private and public sector organizations, by way of sustainability-oriented organizations, cultures, and infrastructure. The diversity in literature exemplifies the developing nature of sustainability science, with most sustainability assessment approaches and frameworks lacking transformational characteristics, tending to focus on analytical methods. In general, some shortfalls in sustainability assessment processes include lack of: · thorough stakeholder participation in systems and stakeholder mapping, · participatory envisioning of future sustainable states, · normative aggregation of results to provide an overall measure of sustainability, and · influence within strategic decision-making processes. Specific to energy sustainability assessments, while some authors aggregate results to provide overall sustainability scores, assessments have focused solely on energy supply scenarios, while including the deficits discussed above. This paper presents a framework for supporting

  20. Calculating Transition Energy Barriers and Characterizing Activation States for Steps of Fusion.

    PubMed

    Ryham, Rolf J; Klotz, Thomas S; Yao, Lihan; Cohen, Fredric S

    2016-03-01

    We use continuum mechanics to calculate an entire least energy pathway of membrane fusion, from stalk formation, to pore creation, and through fusion pore enlargement. The model assumes that each structure in the pathway is axially symmetric. The static continuum stalk structure agrees quantitatively with experimental stalk architecture. Calculations show that in a stalk, the distal monolayer is stretched and the stored stretching energy is significantly less than the tilt energy of an unstretched distal monolayer. The string method is used to determine the energy of the transition barriers that separate intermediate states and the dynamics of two bilayers as they pass through them. Hemifusion requires a small amount of energy independently of lipid composition, while direct transition from a stalk to a fusion pore without a hemifusion intermediate is highly improbable. Hemifusion diaphragm expansion is spontaneous for distal monolayers containing at least two lipid components, given sufficiently negative diaphragm spontaneous curvature. Conversely, diaphragms formed from single-component distal monolayers do not expand without the continual injection of energy. We identify a diaphragm radius, below which central pore expansion is spontaneous. For larger diaphragms, prior studies have shown that pore expansion is not axisymmetric, and here our calculations supply an upper bound for the energy of the barrier against pore formation. The major energy-requiring deformations in the steps of fusion are: widening of a hydrophobic fissure in bilayers for stalk formation, splay within the expanding hemifusion diaphragm, and fissure widening initiating pore formation in a hemifusion diaphragm.