1,166 research outputs found
Level-3 Calorimetric Resolution available for the Level-1 and Level-2 CDF Triggers
As the Tevatron luminosity increases sophisticated selections are required to
be efficient in selecting rare events among a very huge background. To cope
with this problem, CDF has pushed the offline calorimeter algorithm
reconstruction resolution up to Level 2 and, when possible, even up to Level 1,
increasing efficiency and, at the same time, keeping under control the rates.
The CDF Run II Level 2 calorimeter trigger is implemented in hardware and is
based on a simple algorithm that was used in Run I. This system has worked well
for Run II at low luminosity. As the Tevatron instantaneous luminosity
increases, the limitation due to this simple algorithm starts to become clear:
some of the most important jet and MET (Missing ET) related triggers have large
growth terms in cross section at higher luminosity. In this paper, we present
an upgrade of the Level 2 Calorimeter system which makes the calorimeter
trigger tower information available directly to a CPU allowing more
sophisticated algorithms to be implemented in software. Both Level 2 jets and
MET can be made nearly equivalent to offline quality, thus significantly
improving the performance and flexibility of the jet and MET related triggers.
However in order to fully take advantage of the new L2 triggering capabilities
having at Level 1 the same L2 MET resolution is necessary. The new Level-1 MET
resolution is calculated by dedicated hardware. This paper describes the
design, the hardware and software implementation and the performance of the
upgraded calorimeter trigger system both at Level 2 and Level 1.Comment: 5 pages, 5 figures,34th International Conference on High Energy
Physics, Philadelphia, 200
THE CONFLUENCE RATIO OF THE TRANSYLVANIAN BASIN RIVERS
There are many possibilities to assess the hydrological and geomorphological evolution of a territory. Among them, one remarks the confluence ratio of the rivers belonging to different catchment areas. The values of this indicator may provide information regarding the stage of evolution of the fluvial landforms in the Transylvanian Basin. Also, the values may serve for the calculation of other parameters of catchment areas like: the degree of finishing of the drainage basin for its corresponding order, the density of river segments within a catchment area etc. To calculate the confluence ratio, 35 catchment areas of different orders have been selected. The confluence ratio varies between 3.04 and 6.07. The large range of values demonstrates the existence of a heterogeneous lithology and of morphological and hydrographical contrasts from one catchment area to the other. The existence of values above 5, correlated also with observations in the field, reveals an accelerated dynamics of the geomorphological processes in those catchment areas. This dynamic is mainly supported by the high landform fragmentation due to the first order rivers. In contrast, the catchment areas that have a confluence ratio below 5 are in a more advanced stage of evolution with stable slopes, unable to initiate new first order river segments
Charge Generation and Selective Separation at PbS Quantum Dot Metal Oxide Interfaces
Charge separation and transfer at the interface between layers of oleic acid capped PbS quantum dots QDs and Titanium and Indium Tin oxide TiO2 and ITO films were investigated by surface photovoltage SPV measurements. Photoluminescence PL measurements were performed in order to check for excitonic transitions and determine the QD band gaps. The QDs diameter of 4.2 nm and 5.0 nm were estimated by using the PL band gaps and the theoretical equation derived by Wang et al. [J. Chem. Phys. 87 1987 7315]. The SPV spectra of the PbS QDs TiO2 system reveal a positive charge on the PbS film surface and show three distinguished regions which demonstrate i the charge separation across QDs, ii the electron injection from QDs into TiO2 and iii the fundamental absorption in TiO2. The on set of the electron injection depends on the QD size QD band gap it shifts to lower photon energies for lower QD dimensions for higher QD band gaps . Thus, a better conduction band alignment is achieved in the latter case. In contrast to PbS QDs TiO2, the SPV spectra of the PbS QDs ITO structure reveal the negative charge on PbS surface. Moreover, the charge transfer at this interface is not observed. Instead, the SPV peculiarities in the photon energy range 1.4 3.0 eV point out to trapped holes on the ITO surface state
p Si n SiC NANOLAYER PHOTOVOLTAIC CELL
Thin films of amorphous SiC were prepared by non reactive magnetron sputtering in an Ar atmosphere. A previously synthesized SiC was used as a solid state target. Deposition was carried out on a cold substrate of p Si 100 with a resistivity of 2 Ohm amp; 61655;cm. The Raman spectrum shows a dominant band at 982 cm 1, i.e. in the spectral region characteristic for SiC. The film thickness determined from atomic force microscopy measurements was about 8 40 nm, the height of the structural units of the film was 1 2 nm, while the linear dimensions were of the order of tens of nanometers. The amorphous nature of SiC grown on the Si substrate is confirmed by the presence of the diffraction rings which indicate the absence of the dominant orientation of the prepared films. A heterostructure consisting of a p type Si 100 and a layer of amorphous n type SiC was fabricated and studied. The investigation of its electrical and photoelectric properties shows that the entire space charge region is located in Si. This is in addition confirmed by the spectral dependence of the p Si n SiC photo sensitivity. The barrier height at the p Si n SiC interface estimated from dark I V characteristics is of the order of 0.9 1.0 eV. Load I V characteristics of p Si n SiC amorphous nanolayer solar cells demonstrate under standard AM1.5 illumination conditions a conversion efficiency of 7.2
Database Learning: Toward a Database that Becomes Smarter Every Time
In today's databases, previous query answers rarely benefit answering future
queries. For the first time, to the best of our knowledge, we change this
paradigm in an approximate query processing (AQP) context. We make the
following observation: the answer to each query reveals some degree of
knowledge about the answer to another query because their answers stem from the
same underlying distribution that has produced the entire dataset. Exploiting
and refining this knowledge should allow us to answer queries more
analytically, rather than by reading enormous amounts of raw data. Also,
processing more queries should continuously enhance our knowledge of the
underlying distribution, and hence lead to increasingly faster response times
for future queries.
We call this novel idea---learning from past query answers---Database
Learning. We exploit the principle of maximum entropy to produce answers, which
are in expectation guaranteed to be more accurate than existing sample-based
approximations. Empowered by this idea, we build a query engine on top of Spark
SQL, called Verdict. We conduct extensive experiments on real-world query
traces from a large customer of a major database vendor. Our results
demonstrate that Verdict supports 73.7% of these queries, speeding them up by
up to 23.0x for the same accuracy level compared to existing AQP systems.Comment: This manuscript is an extended report of the work published in ACM
SIGMOD conference 201
Development of a stochastic computational fluid dynamics approach for offshore wind farms
In this paper, a method for stochastic analysis of an offshore wind farm using computational fluid dynamics (CFD) is proposed. An existing offshore wind farm is modelled using a steady-state CFD solver at several deterministic input ranges and an approximation model is trained on the CFD results. The approximation model is then used in a Monte-Carlo analysis to build joint probability distributions for values of interest within the wind farm. The results are compared with real measurements obtained from the existing wind farm to quantify the accuracy of the predictions. It is shown that this method works well for the relatively simple problem considered in this study and has potential to be used in more complex situations where an existing analytical method is either insufficient or unable to make a good prediction
Experimental aspects regarding the malolactic fermentation of some red and white wines
This scientific paper
presents some aspects typical of the process
of malolactic fermentation in some wines,
respectively, the variation of total, volatile
and real acidity (pH), malic acid
metabolization and formation of lactic acid,
as well as the changes of some composition
characteristics (tartaric and citric acids,
potassium, calcium, reducing sugars and
phenolic compounds). Trials were
conducted on seven different wines from the
harvest of year 2007: two white wines
obtained from Rkaţiteli and Zghihară
varieties and five red varieties (Burgund
mare, Băbească neagră, Cabernet
Sauvignon, Merlot and Fetească neagră).
We have studied some wines according to
their pH values (3.085, 3.135, 3.264, 3.352,
3.422, 3.470 and 3.505) and total acidity
(9.96, 8.84, 7.88, 7.56, 7.25, 6.94, 6.63 g/L
C4H6O6), which are significant in the
development of the malolactic fermentation.
The investigations were carried out under
laboratory conditions, for 40 days. For
starting the malolactic fermentation, at the
end of wine alcoholic fermentation (after 7-
15 days), selected malolactic bacteria
(SMB) from the Biolact assortment
(Oenococcus oeni class) were added in
wines as leaven. By the action of malolactic
bacteria, we found in all the studied wines a
differentiated diminution (according to the
initial values of total acidity and of pH) in
the concentration of malic acid, correlated
to an increase in the lactic acid content. The
modifications of the other composition
characteristics sustained the evolution of
malolactic fermentation, realised by the
great diminution of total acidity and the pH
increase, after a certain period (about 16-24
days)
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