39 research outputs found
Estimating COâ emissions for 108000 European cities
City-level COâ emissions inventories are foundational for supporting the EU's decarbonization goals. Inventories are essential for priority setting and for estimating impacts from the decarbonization transition. Here we present a new COâ emissions inventory for all 116572 municipal and local-government units in Europe, containing 108000 cities at the smallest scale used. The inventory spatially disaggregates the national reported emissions, using nine spatialization methods to distribute the 167 line items detailed in the National Inventory Reports (NIRs) using the UNFCCC (United Nations Framework Convention on Climate Change) Common Reporting Framework (CRF). The novel contribution of this model is that results are provided per administrative jurisdiction at multiple administrative levels, following the region boundaries defined OpenStreetMap, using a new spatialization approach
Validation of three-component wind lidar sensor for traceable highly resolved wind vector measurements
Conventional monostatic wind lidar (light detection
and ranging) systems are well-established wind speed
remote sensing devices in the field of wind energy that provide reliable
measurement results for flat terrain and homogeneous wind fields. These
conventional wind lidar systems use a common transmitting and receiving unit
and become unacceptably inaccurate as the wind fields become increasingly
inhomogeneous due to their spatial and temporal averaging procedure (large
measurement volume) that is inherent to the monostatic measurement principle.
The new three-component fiber laser-based wind lidar sensor developed by the
Physikalisch-Technische Bundesanstalt (PTB) uses one transmitting unit (fiber
laser) and three receiving units to measure the velocity vector of single
aerosols in a spatially highly resolved measurement volume (with diameter
d and length l) in heights from 5 m (d=300 ”m, l=2 mm) to 250 m (d=14 mm, l=4 m) with a resolution of about 0.1 m sâ1.
Detailed comparison measurements
with a 135 m high wind met mast and a conventional lidar system have
proven that the high spatial and temporal resolution of the new, so-called
bistatic lidar leads to a reduced measurement uncertainty compared to
conventional lidar systems. Furthermore, the comparison demonstrates that the
deviation between the bistatic lidar and the wind met mast lies well within
the measurement uncertainty of the cup anemometers of the wind met mast for
both homogeneous and inhomogeneous wind fields. At PTB, the aim is to use the
bistatic wind lidar as a traceable reference standard to calibrate other
remote sensing devices, necessitating an in-depth validation of the bistatic
lidar system and its measurement uncertainty. To this end, a new, specially
designed wind tunnel with a laser Doppler anemometer (LDA) as flow velocity
reference has been erected on a platform at a height of 8 m; this allows the
new wind lidar to be positioned below the wind tunnel test section to be
validated for wind vector measurements that are traceable to the SI units. A
first validation measurement within the wind tunnel test section is
presented, showing a deviation between the bistatic lidar system and the LDA clearly
below 0.1 %.</p
Skipping orbits and enhanced resistivity in large-diameter InAs/GaSb antidot lattices
We investigated the magnetotransport properties of high-mobility InAs/GaSb
antidot lattices. In addition to the usual commensurability features at low
magnetic field we found a broad maximum of classical origin around 2.5 T. The
latter can be ascribed to a class of rosetta type orbits encircling a single
antidot. This is shown by both a simple transport calculation based on a
classical Kubo formula and an analysis of the Poincare surface of section at
different magnetic field values. At low temperatures we observe weak
1/B-periodic oscillations superimposed on the classical maximum.Comment: 4 pages, 4 Postscript figures, REVTeX, submitted to Phys Rev
Screening Breakdown on the Route toward the Metal-Insulator Transition in Modulation Doped Si/SiGe Quantum Wells
Exploiting the spin resonance of two-dimensional (2D) electrons in SiGe/Si
quantum wells we determine the carrier-density-dependence of the magnetic
susceptibility. Assuming weak interaction we evaluate the density of states at
the Fermi level D(E_F), and the screening wave vector, q_TF. Both are constant
at higher carrier densities n, as for an ideal 2D carrier gas. For n < 3e11
cm-2, they decrease and extrapolate to zero at n = 7e10 cm-2. Calculating the
mobility from q_TF yields good agreement with experimental values justifying
the approach. The decrease in D(E_F) is explained by potential fluctuations
which lead to tail states that make screening less efficient and - in a
positive feedback - cause an increase of the potential fluctuations. Even in
our high mobility samples the fluctuations exceed the electron-electron
interaction leading to the formation of puddles of mobile carriers with at
least 1 micrometer diameter.Comment: 4 pages, 3 figure
Edge-Magnetoplasmon Wave-Packet Revivals in the Quantum Hall Effect
The quantum Hall effect is necessarily accompanied by low-energy excitations
localized at the edge of a two-dimensional electron system. For the case of
electrons interacting via the long-range Coulomb interaction, these excitations
are edge magnetoplasmons. We address the time evolution of localized
edge-magnetoplasmon wave packets. On short times the wave packets move along
the edge with classical E cross B drift. We show that on longer times the wave
packets can have properties similar to those of the Rydberg wave packets that
are produced in atoms using short-pulsed lasers. In particular, we show that
edge-magnetoplasmon wave packets can exhibit periodic revivals in which a
dispersed wave packet reassembles into a localized one. We propose the study of
edge-magnetoplasmon wave packets as a tool to investigate dynamical properties
of integer and fractional quantum-Hall edges. Various scenarios are discussed
for preparing the initial wave packet and for detecting it at a later time. We
comment on the importance of magnetoplasmon-phonon coupling and on quantum and
thermal fluctuations.Comment: 18 pages, RevTex, 7 figures and 2 tables included, Fig. 5 was
originally 3Mbyte and had to be bitmapped for submission to archive; in the
process it acquired distracting artifacts, to upload the better version, see
http://physics.indiana.edu/~uli/publ/projects.htm
Charakterisierung superglatter OberflÀchen
Zur Untersuchung superglatter OberflĂ€chen wurden neuartige MeĂinstrumente und Auswerteverfahren entwickelt und bei der Charakterisierung verschiedener Werkstoffe eingesetz