GEFCOM 2014 - Probabilistic Electricity Price Forecasting

Energy price forecasting is a relevant yet hard task in the field of multi-step time series forecasting. In this paper we compare a well-known and established method, ARMA with exogenous variables with a relatively new technique Gradient Boosting Regression. The method was tested on data from Global Energy Forecasting Competition 2014 with a year long rolling window forecast. The results from the experiment reveal that a multi-model approach is significantly better performing in terms of error metrics. Gradient Boosting can deal with seasonality and auto-correlation out-of-the box and achieve lower rate of normalized mean absolute error on real-world data.Comment: 10 pages, 5 figures, KES-IDT 2015 conference. The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-19857-6_

Non-exponential one-body loss in a Bose-Einstein condensate

We have studied the decay of a Bose-Einstein condensate of metastable helium atoms in an optical dipole trap. In the regime where two- and three-body losses can be neglected we show that the Bose-Einstein condensate and the thermal cloud show fundamentally different decay characteristics. The total number of atoms decays exponentially with time constant tau; however, the thermal cloud decays exponentially with time constant (4/3)tau and the condensate decays much faster, and non-exponentially. We show that this behaviour, which should be present for all BECs in thermal equilibrium with a considerable thermal fraction, is due to a transfer of atoms from the condensate to the thermal cloud during its decay.Comment: The intuitive explanation of the atomic transfer effect has been correcte

Cross-Talk-Free Multi-Color STORM Imaging Using a Single Fluorophore

Multi-color stochastic optical reconstruction microscopy (STORM) is routinely performed; however, the various approaches for achieving multiple colors have important caveats. Color cross-talk, limited availability of spectrally distinct fluorophores with optimal brightness and duty cycle, incompatibility of imaging buffers for different fluorophores, and chromatic aberrations impact the spatial resolution and ultimately the number of colors that can be achieved. We overcome these complexities and develop a simple approach for multi-color STORM imaging using a single fluorophore and sequential labelling. In addition, we present a simple and versatile method to locate the same region of interest on different days and even on different microscopes. In combination, these approaches enable cross-talk-free multi-color imaging of sub-cellular structures.Peer ReviewedPostprint (published version

POLITIKAI ÉS HATÉKONYSÃGI CÉLOK KONFLIKTUSA AZ EU CUKORPIACI REFORMJÃBAN

Az elemzés, a cukorreform hátterének vázlatos bemutatását követÅ‘en, a kvótacsökkentés lebonyolításának hatékonysági összefüggéseire irányul. Az európai cukorágazat reformjának egyik fÅ‘ mozgatórugója a hatékonyság, melyet a merev nemzeti kvótákra épülÅ‘ szabályozás eddig nem mozdított elÅ‘ kellÅ‘képpen. Ehhez társul az ártámogatás termeléstÅ‘l való függetlenítése, valamint a túltermelés kezelésének szükségessége is, mivel az Európai Uniót nemzetközi kereskedelmi kötelezettségei a cukorexport radikális csökkentésére és az import mennyiségének jelentÅ‘s növelésére kényszerítik. A termelés irányított csökkentésére a Közösség szerkezetváltási programot hirdetett meg, amely elvileg a kevésbé versenyképes termelÅ‘k kilépését eredményezi. Az EU becsült cukorkínálati függvénye alapján lehetÅ‘ség van a különbözÅ‘ kvótacsökkentési lehetÅ‘ségek összehasonlítására, a jóléti közgazdaságtan módszereinek felhasználásával. Ennek segítségével kimutatható, hogy egy egyszerű lineáris kvótacsökkentés, éves szinten, mintegy félmilliárd eurós hatékonysági veszteséget jelent z önkéntes serkezetváltási programhoz képest. A jelenleg folyó cukorreform egyik alapkérdése tehát az, hogy sikerül-e ezt az elméleti hatékonysági potenciált a gyakorlatban is kiaknázni? Az elemzés arra a következtetésre jut, hogy e nélkül a reformban célul kitÅ‘zött piaci cukorárak megközelítésére nincs esély. - Beyond sketching the background to EU sugar reform the present report concerns the relationships between efficiencies in accomplishing quota reductions. One of the main reasons for reforming the European sugar sector was efficiency, which could not be significantly improved because of national regulations based on rigid quotas. Other reasons were the separation of price support from production and the need to control overproduction because of international trading commitments required the EU to reduce sugar exports radically and increase sugar imports significantly. To achieve planned reduction in production the Community proposed a program of structural change bringing about the exclusion of the lesser competitive producers. On the basis of EU’s estimated sugar supply function it is possible to compare various possibilities for quota reductions using the methods of social welfare economics. In this way it can be shown that a system of simple liner quota reductions would bring about an annual loss of half billion euro in efficiency as compared with a program of voluntary structural change. The basic question in the sugar reform being presently enforced is whether or not it will be possible to exploit the theoretical value of efficiency in practice. We have come to the conclusion that without the full exploitation of efficiencies planned there is no chance of achieving the market prices of sugar projected in the reform.cukorreform, cukorpiac, kvótaszabályozás, szerkezetváltási program, hatékonyság, sugar reform, sugar market, quota regulation, program for structural change, efficiency, Agricultural and Food Policy, Crop Production/Industries, International Relations/Trade,

Backcasting and forecasting biological invasions of inland lakes

Human introduction of nonindigenous species constitutes a serious threat to many ecosystems, particularly lakes. Recent attempts to predict invasions have focused on the supply of propagules of nonindigenous species to recipient ecosystems from source populations. Here we develop a spatially explicit “gravity” model to test this concept for Bythotrephes longimanus, a crustacean waterflea from Eurasia that is rapidly invading lakes in Ontario, Canada. The gravity model predicted spread of Bythotrephes based upon seven identified risk factors (e.g., use of contaminated fishing or boat anchor line) that may allow dispersal of either live individuals or their resting eggs from invaded to noninvaded lakes, as well as based on the spatial arrangement of invaded and noninvaded lakes in Ontario. Discriminant analysis of lake gravity scores successfully identified invasion status for 74% of 170 inland lakes. A retrospective analysis of 31 invaded lakes revealed that the order in which lakes were invaded was directly related to the magnitude of vector inflows from invaded sources. Analysis of the dominant vector inflow to each invaded lake revealed a “stepping stone” pattern in which at least five lakes were sequentially invaded from the source population in Lake Huron. One invaded lake (Muskoka) apparently served as an invasion “hub,” resulting in up to 18 additional direct and 17 indirect invasions. Species spread occurred via a combination of dominant, local diffusion (median distance 12.5 km) and rare, long-distance (\u3e100 km) dispersal. Eleven of 131 lakes that were not invaded in 2000 were reported invaded in 2001. Gravity scores of these lakes were significantly higher than those of other noninvaded systems, indicating that susceptibility to invasion can be related to the magnitude of vector inflows. A GIS model based on gravity scores indicated that distribution of Bythotrephes is expected to expand to eastern and northwestern Ontario, although most new invasions are expected to occur in the central region of the province. Our results indicate that quantitative analysis of human dispersal vectors provides a robust starting point with which to assess vulnerability of discrete ecosystems to invasion. Management efforts focused on reducing the number and magnitude of human-mediated dispersal vectors may reduce the rate of invasion of new ecosystems

Novel Co 20 Cr 15 Fe 26 Mn 17 Ni 22 ultra-fine grained high-entropy alloy

International audienceIn a non-equiatomic HEA from CoCrFeMnNi family, so-called A3S® alloy (austenitic superstainless steel), exceptional mechanical properties are observed. High yield strength (800 MPa) associated with significant elongation to fracture (35 %) and a stable austenitic paramagnetic structure (down to LN2 temperature) may be obtained in hot forged materials. Mechanical resistance (YS) of A3S is at least 200 MPa higher than that measured in equiatomic alloy (EA) of the same family. These properties come from a nanostructure, easily formed in the material after classical hot thermomechanical treatment (forging). Yet, mechanical resistance of A3S decreases strongly after a post-forging high temperature annealing: in this state, identical behaviors of A3S and EA are noticed. Effects of thermal conditions of forging and recrystallization annealing have been investigated in A3S. Only slight effect of temperature of forging (between 900 and 1100°C) has been shown. Surprising effects of recrystallization annealing have been found. Low temperature (up to 600°C for 48h) treatment leads to recrystallization with formation of fine (1 µm) grains. At higher temperatures (700-1100°C), recrystallization is blocked: only recovery followed by grain growth and formation of numerous twins is observed. Moreover, in this state, very high density of dislocations is conserved: they present ordered configurations with alignments in {111} planes. Formation of twins has major effect on mechanical behavior of both A3S and EA. Their absence stabilizes nanostructures and leads to high YS values while decrease of YS is accompanied by twins presence. Relative difficulty to form these defects in A3S (as compared to EA) is explained by high value of stacking fault energy, evaluated from TEM measurements of dislocations dissociation. Moreover, strong dependence of SFE on temperature has been shown: its lower value at high temperatures is in agreement with numerous twins observed