297 research outputs found
Multivariate Simulation-based Forecasting for Intraday Power Markets: Modelling Cross-Product Price Effects
Intraday electricity markets play an increasingly important role in balancing
the intermittent generation of renewable energy resources, which creates a need
for accurate probabilistic price forecasts. However, research to date has
focused on univariate approaches, while in many European intraday electricity
markets all delivery periods are traded in parallel. Thus, the dependency
structure between different traded products and the corresponding cross-product
effects cannot be ignored. We aim to fill this gap in the literature by using
copulas to model the high-dimensional intraday price return vector. We model
the marginal distribution as a zero-inflated Johnson's distribution with
location, scale and shape parameters that depend on market and fundamental
data. The dependence structure is modelled using latent beta regression to
account for the particular market structure of the intraday electricity market,
such as overlapping but independent trading sessions for different delivery
days. We allow the dependence parameter to be time-varying. We validate our
approach in a simulation study for the German intraday electricity market and
find that modelling the dependence structure improves the forecasting
performance. Additionally, we shed light on the impact of the single intraday
coupling (SIDC) on the trading activity and price distribution and interpret
our results in light of the market efficiency hypothesis. The approach is
directly applicable to other European electricity markets
A constrained supersymmetric left-right model
We present a supersymmetric left-right model which predicts gauge coupling
unification close to the string scale and extra vector bosons at the TeV scale.
The subtleties in constructing a model which is in agreement with the measured
quark masses and mixing for such a low left-right breaking scale are discussed.
It is shown that in the constrained version of this model radiative breaking of
the gauge symmetries is possible and a SM-like Higgs is obtained. Additional
CP-even scalars of a similar mass or even much lighter are possible. The
expected mass hierarchies for the supersymmetric states differ clearly from
those of the constrained MSSM. In particular, the lightest down-type squark,
which is a mixture of the sbottom and extra vector-like states, is always
lighter than the stop. We also comment on the model's capability to explain
current anomalies observed at the LHC.Comment: 21 pages, 5 figures; v2: references added, matches published versio
A generalization of Geroch's conjecture
The Theorem of Bonnet--Myers implies that manifolds with topology do not admit a metric of positive Ricci curvature, while
the resolution of Geroch's conjecture implies that the torus
does not admit a metric of positive scalar curvature. In this work we introduce
a new notion of curvature interpolating between Ricci and scalar curvature (so
called -intermediate curvature), and use stable weighted slicings to show
that for the manifolds do not
admit a metric of positive -intermediate curvature.Comment: final version; to appear in Comm. Pure. Appl. Mat
Forest, Wood and Climate Change: Challenges and Opportunities in the UNECE Region
This essay explains the importance of the forests as a factor in addressing the challenges in mitigating climate change. The potential of using the forest sector more fully to capture and store carbon has been limited by the failure of current protocols and other climate change mechanisms to adequately account for the contribution of this sector. Thus, a better accounting, which will give the proper credit to the impacts that this sector is having, is viewed to be an important next step to increasing the resources that countries will devote to this factor in addressing climate change. The degree to which global warming is already affecting the forest is also discussed; increasingly mankind may be required to be more proactive in implementing “planned adaptation” activities such as increasing the diversification of forestry resources.Climate change, global warming, forest, biofuels
Dark matter and LHC phenomenology in a left-right supersymmetric model
Left-right symmetric extensions of the Minimal Supersymmetric Standard Model can explain neutrino data and have potentially interesting phenomenology beyond that found in minimal SUSY seesaw models. Here we study a SUSY model in which the left-right symmetry is broken by triplets at a high scale, but significantly below the GUT scale. Sparticle spectra in this model differ from the usual constrained MSSM expectations and these changes affect the relic abundance of the lightest neutralino. We discuss changes for the standard stau (and stop) co-annihilation, the Higgs funnel and the focus point regions. The model has potentially large lepton flavour violation in both, left and right, scalar leptons and thus allows, in principle, also for flavoured co-annihilation. We also discuss lepton flavour signals due to violating decays of the second lightest neutralino at the LHC, which can be as large as 20 fb(-1) at root s = 14 TeV
Nobody’s perfect: interactive synthesis from parametrized real-time scenarios
ABSTRACT As technical systems keep growing more complex and sophisticated, designing software for the safety-critical coordination between their components becomes increasingly difficult. Verifying and correcting these components already represents a significant part of the development process both with respect to time and cost. Scenario-based synthesis has been put forward as an approach to accelerate the transition from requirements to a correct, verified model. I
Late Quaternary aeolian dynamics, pedostratigraphy and soil formation in the North European Lowlands – new findings from the Baruther ice-marginal valley
The construction of dunes in central Europe reflects ample sediment supply during the last deglacial hemicycle. A Quaternary inland dune complex in southern Brandenburg, Germany, was studied to determine the duration of recent pedogenesis, from two outcrops, which show buried paleosols. An integrative approach, which combined geomorphological, sedimentological, (paleo-)pedological and chronological methods was used to identify aeolian deposition events, ensuing pedogenesis and anthropogenic remobilization. At the outcrops, which were situated approximately 2 km apart from each other, in total twelve samples of the aeolian sands were dated using optically stimulated luminescence (OSL) and six using 14C dating. Although the dunes have similar morphological features, these forms have a different history of aeolian sand deposition and pedogenesis. At the older dune (Gl 1) the surface soil is a well developed Podzol, whereas soil development of the younger dune (Gl 2) is clearly in an initial state. The two dunes also differ in grain size distribution and in the presence of buried soils, thereby indicating a climatic impact on aeolian remobilization
Messung von Schwermetallen und Hauptelementen in anthropogen geprägten Böden mittels feldportabler Röntgenfluoreszenzanalyse (FP RFA)
Der Einsatz eines feldportablen Röntgenfluoreszenzanalysators (FP RFA) vom Typ NITON XL3t, zur Messung von Schwermetallen und Hauptelementen in Bodenproben wurde am Beispiel eines ehemaligen Rieselfelds untersucht. Die Gegenüberstellung der RFA Daten zu nasschemisch gewonnenen Messwerten zeigte insbesondere für die Elemente Kupfer, Blei und Zink eine starke Korrelation zwischen beiden Datensätzen. Die Elemente Calcium, Kalium, Phosphor und Magnesium konnten im untersuchten Messwertbereich nicht befriedigend analysiert werden. Die in-situ Messung ergab mit Labordaten vergleichbare Messwerte und Messwertverteilungen, wenngleich im Feld z.T. deutlich höhere Metallgehalte bestimmt wurden
Perturbing exactly tri-bimaximal neutrino mixings with charged lepton mass matrices
We study perturbations of exactly tri-bimaximal neutrino mixings under the
assumption that they are coming solely from the charged lepton mass matrix.
This may be plausible in scenarios where the mass generation mechanisms of
neutrinos and charged leptons/quarks have a different origin. As a working
hypothesis, we assume mass textures which may be generated by the
Froggatt-Nielsen mechanism for the charged lepton and quark sectors, which
generically leads to strong hierarchies, whereas the neutrino sector is exactly
tri-bimaximal with a mild (normal) hierarchy. We find that in this approach,
deviations from maximal atmospheric mixing can be introduced without affecting
theta_13 and theta_12, whereas a deviation of theta_13 or theta_12 from its
tri-bimaximal value will inevitably lead to a similar-sized deviation of the
other parameter. Therefore, the already very precise knowledge of theta_12
points towards small sin^2(2 theta_13) <= 0.01. The magnitude of this deviation
can be controlled by the specific form of the charged lepton texture.Comment: 13 pages, 9 figures; matches published version, changes in notatio
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