TY - JOUR A1 - Dürig, Tobias A1 - Gudmundsson, Magnús Tumi A1 - Karmann, Sven A1 - Zimanowski, Bernd A1 - Dellino, Pierfrancesco A1 - Rietze, Martin A1 - Büttner, Ralf T1 - Mass eruption rates in pulsating eruptions estimated from video analysis of the gas thrust-buoyancy transition-a case study of the 2010 eruption of Eyjafjallajökull, Iceland JF - Earth, Planets and Space N2 - The 2010 eruption of Eyjafjallajokull volcano was characterized by pulsating activity. Discrete ash bursts merged at higher altitude and formed a sustained quasi-continuous eruption column. High-resolution near-field videos were recorded on 8-10 May, during the second explosive phase of the eruption, and supplemented by contemporary aerial observations. In the observed period, pulses occurred at intervals of 0.8 to 23.4 s (average, 4.2 s). On the basis of video analysis, the pulse volume and the velocity of the reversely buoyant jets that initiated each pulse were determined. The expansion history of jets was tracked until the pulses reached the height of transition from a negatively buoyant jet to a convective buoyant plume about 100 m above the vent. Based on the assumption that the density of the gas-solid mixture making up the pulse approximates that of the surrounding air at the level of transition from the jet to the plume, a mass flux ranging between 2.2 and 3.5 . 10\(^4\) kg/s was calculated. This mass eruption rate is in good agreement with results obtained with simple models relating plume height with mass discharge at the vent. Our findings indicate that near-field measurements of eruption source parameters in a pulsating eruption may prove to be an effective monitoring tool. A comparison of the observed pulses with those generated in calibrated large-scale experiments reveals very similar characteristics and suggests that the analysis of near-field sensors could in the future help to constrain the triggering mechanism of explosive eruptions. KW - image KW - dynamics KW - infrasound KW - entrainment KW - jets KW - plumes KW - source parameters KW - Eyjafjallajökull 2010 KW - pulsating explosive eruptions KW - near-field monitoring KW - eruption rate KW - volcano KW - energy KW - models KW - explosive volcanism KW - mass Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138635 VL - 67 IS - 180 ER - TY - JOUR A1 - Kümmel, Reiner A1 - Lindenberger, Dietmar T1 - How energy conversion drives economic growth far from the equilibrium of neoclassical economics JF - New Journal of Physics N2 - Energy conversion in the machines and information processors of the capital stock drives the growth of modern economies. This is exemplified for Germany, Japan, and the USA during the second half of the 20th century: econometric analyses reveal that the output elasticity, i.e. the economic weight, of energy is much larger than energyʼs share in total factor cost, while for labor just the opposite is true. This is at variance with mainstream economic theory according to which an economy should operate in the neoclassical equilibrium, where output elasticities equal factor cost shares. The standard derivation of the neoclassical equilibrium from the maximization of profit or of time-integrated utility disregards technological constraints. We show that the inclusion of these constraints in our nonlinear-optimization calculus results in equilibrium conditions, where generalized shadow prices destroy the equality of output elasticities and cost shares. Consequently, at the prices of capital, labor, and energy we have known so far, industrial economies have evolved far from the neoclassical equilibrium. This is illustrated by the example of the German industrial sector evolving on the mountain of factor costs before and during the first and the second oil price explosion. It indicates the influence of the 'virtually binding' technological constraints on entrepreneurial decisions, and the existence of 'soft constraints' as well. Implications for employment and future economic growth are discussed. KW - economic growth KW - technological constraints KW - output elasticities KW - energy Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-118102 SN - 1367-2630 VL - 16 IS - 125008 ER - TY - JOUR A1 - Kümmel, Reiner A1 - Lindenberger, Dietmar T1 - Energy, entropy, constraints, and creativity in economic growth and crises JF - Entropy N2 - The neoclassical mainstream theory of economic growth does not care about the First and the Second Law of Thermodynamics. It usually considers only capital and labor as the factors that produce the wealth of modern industrial economies. If energy is taken into account as a factor of production, its economic weight, that is its output elasticity, is assigned a meager magnitude of roughly 5 percent, according to the neoclassical cost-share theorem. Because of that, neoclassical economics has the problems of the “Solow Residual”, which is the big difference between observed and computed economic growth, and of the failure to explain the economic recessions since World War 2 by the variations of the production factors. Having recalled these problems, we point out that technological constraints on factor combinations have been overlooked in the derivation of the cost-share theorem. Biophysical analyses of economic growth that disregard this theorem and mend the neoclassical deficiencies are sketched. They show that energy’s output elasticity is much larger than its cost share and elucidate the existence of bidirectional causality between energy conversion and economic growth. This helps to understand how economic crises have been triggered and overcome by supply-side and demand-side actions. Human creativity changes the state of economic systems. We discuss the challenges to it by the risks from politics and markets in conjunction with energy sources and technologies, and by the constraints that the emissions of particles and heat from entropy production impose on industrial growth in the biosphere. KW - energy KW - economic growth KW - output elasticities KW - entropy production KW - emissions KW - optimization Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-216275 SN - 1099-4300 VL - 22 IS - 10 ER - TY - JOUR A1 - Kümmel, Reiner A1 - Lindenberger, Dietmar T1 - Energy in Growth Accounting and the Aggregation of Capital and Output JF - Biophysical Economics and Sustainability N2 - We review the physical aggregation of value added and capital in terms of work performance and information processing and its relation to the deflated monetary time series of output and capital. In growth accounting it complements the time series of labor and energy, measured in hours worked per year and kilowatt-hours consumed per year, respectively. This aggregation is the conceptual basis on which those energy-dependent production functions have been constructed that reproduce economic growth of major industrial countries in the 20th century with small residuals and output elasticities that are for energy much larger and for labor much smaller than the cost shares of these factors. Accounting for growth in such a way, which deviates from that of mainstream economics, may serve as a first step towards integrating the First and the Second Law of Thermodynamics into economics. KW - aggregation KW - cost-share theorem KW - economic growth KW - energy KW - entropy KW - output elasicities Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-241135 VL - 5 ER - TY - JOUR A1 - Sauer, C A1 - Wießner, M A1 - Schöll, A A1 - Reinert, F T1 - Observation of a molecule-metal interface charge transfer related feature by resonant photoelectron spectroscopy JF - New Journal of Physics N2 - We report the discovery of a charge transfer (CT) related low binding energy feature at a molecule-metal interface by the application of resonant photoelectron spectroscopy (RPES). This interface feature is neither present for molecular bulk samples nor for the clean substrate. A detailed analysis of the spectroscopic signature of the low binding energy feature shows characteristics of electronic interaction not found in other electron spectroscopic techniques. Within a cluster model description this feature is assigned to a particular eigenstate of the photoionized system that is invisible in direct photoelectron spectroscopy but revealed in RPES through a relative resonant enhancement. Interpretations based on considering only the predominant character of the eigenstates explain the low binding energy feature by an occupied lowest unoccupied molecular orbital, which is either realized through CT in the ground or in the intermediate state. This reveals that molecule-metal CT is responsible for this feature. Consequently, our study demonstrates the sensitivity of RPES to electronic interactions and constitutes a new way to investigate CT at molecule-metal interfaces. KW - transfer dynamics KW - photoemission KW - states KW - interface KW - charge transfer KW - organic thin films KW - resonant photoelectron spectroscopy KW - energy KW - model calculation KW - NEXAFS spectroscopy KW - ce compounds KW - absorption Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148672 VL - 17 IS - 043016 ER - TY - JOUR A1 - Shukla, A. A1 - Mannheim, K. T1 - Gamma-ray flares from relativistic magnetic reconnection in the jet of the quasar 3C 279 JF - Nature Communications N2 - Spinning black holes in the centres of galaxies can release powerful magnetised jets. When the jets are observed at angles of less than a few degrees to the line-of-sight, they are called blazars, showing variable non-thermal emission across the electromagnetic spectrum from radio waves to gamma rays. It is commonly believed that shock waves are responsible for this dissipation of jet energy. Here we show that gamma-ray observations of the blazar 3C 279 with the space-borne telescope Fermi-LAT reveal a characteristic peak-in-peak variability pattern on time scales of minutes expected if the particle acceleration is instead due to relativistic magnetic reconnection. The absence of gamma-ray pair attenuation shows that particle acceleration takes place at a distance of ten thousand gravitational radii from the black hole where the fluid dynamical kink instability drives plasma turbulence. KW - kink instability KW - energy KW - radiation KW - blazars KW - variability KW - absorption KW - telescope KW - shocks Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231328 VL - 11 ER - TY - JOUR A1 - Thierschmann, H A1 - Arnold, F A1 - Mittermüller, M A1 - Maier, L A1 - Heyn, C A1 - Hansen, W A1 - Buhmann, H A1 - Molenkamp, L W T1 - Thermal gating of charge currents with Coulomb coupled quantum dots JF - New Journal of Physics N2 - We have observed thermal gating, i.e. electrostatic gating induced by hot electrons. The effect occurs in a device consisting of two capacitively coupled quantum dots. The double dot system is coupled to a hot electron reservoir on one side (QD1), while the conductance of the second dot (QD2) is monitored. When a bias across QD2 is applied we observe a current which is strongly dependent on the temperature of the heat reservoir. This current can be either enhanced or suppressed, depending on the relative energetic alignment of the QD levels. Thus, the system can be used to control a charge current by hot electrons. KW - oscillations KW - physics KW - quantum dot systems KW - Coulomb interaction KW - thermal gating KW - three terminal device KW - thermoelectrics KW - energy KW - thermopower Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145196 VL - 17 IS - 113003 ER - TY - JOUR A1 - Timmermans, Wim J. A1 - van der Tol, Christiaan A1 - Timmermans, Joris A1 - Ucer, Murat A1 - Chen, Xuelong A1 - Alonso, Luis A1 - Moreno, Jose A1 - Carrara, Arnaud A1 - Lopez, Ramon A1 - Fernando de la Cruz, Tercero A1 - Corcoles, Horacio L. A1 - de Miguel, Eduardo A1 - Sanchez, Jose A. G. A1 - Perez, Irene A1 - Belen, Perez A1 - Munoz, Juan-Carlos J. A1 - Skokovic, Drazen A1 - Sobrino, Jose A1 - Soria, Guillem A1 - MacArthur, Alasdair A1 - Vescovo, Loris A1 - Reusen, Ils A1 - Andreu, Ana A1 - Burkart, Andreas A1 - Cilia, Chiara A1 - Contreras, Sergio A1 - Corbari, Chiara A1 - Calleja, Javier F. A1 - Guzinski, Radoslaw A1 - Hellmann, Christine A1 - Herrmann, Ittai A1 - Kerr, Gregoire A1 - Lazar, Adina-Laura A1 - Leutner, Benjamin A1 - Mendiguren, Gorka A1 - Nasilowska, Sylwia A1 - Nieto, Hector A1 - Pachego-Labrador, Javier A1 - Pulanekar, Survana A1 - Raj, Rahul A1 - Schikling, Anke A1 - Siegmann, Bastian A1 - von Bueren, Stefanie A1 - Su, Zhongbo (Bob) T1 - An Overview of the Regional Experiments for Land-atmosphere Exchanges 2012 (REFLEX 2012) Campaign JF - Acta Geophysica N2 - The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites. After presenting the different types of measurements, some examples are given to illustrate the potential of the observations made. KW - multi scale heterogeneity KW - quantitative remote sensing KW - remote KW - evapotranspiration KW - validation KW - issues KW - energy KW - models KW - water KW - flux KW - land-atmosphere interaction KW - turbulence KW - calibration and validation Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-136491 VL - 63 IS - 6 ER - TY - JOUR A1 - Wiessner, M. A1 - Rodriguez Lastra, N. S. A1 - Ziroff, J. A1 - Forster, F. A1 - Puschnig, P. A1 - Dössel, L. A1 - Müllen, K. A1 - Schöll, A. A1 - Reinert, F. T1 - Different views on the electronic structure of nanoscale graphene: aromatic molecule versus quantum dot JF - New Journal of Physics N2 - Graphene's peculiar electronic band structure makes it of interest for new electronic and spintronic approaches. However, potential applications suffer from quantization effects when the spatial extension reaches the nanoscale. We show by photoelectron spectroscopy on nanoscaled model systems (disc-shaped, planar polyacenes) that the two-dimensional band structure is transformed into discrete states which follow the momentum dependence of the graphene Bloch states. Based on a simple model of quantum wells, we show how the band structure of graphene emerges from localized states, and we compare this result with ab initio calculations which describe the orbital structure. KW - well KW - confinement KW - states KW - Ag(111) KW - photoemission KW - vicinal surfaces KW - coronene KW - energy KW - films KW - nanographenes Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130184 VL - 14 IS - 113008 ER -