1,426 research outputs found
Quasi-gaussian fixed points and factorial cumulants in nuclear multifragmentation
We re-analyze the conditions for the phenomenon of intermittency
(self-similar fluctuations) to occur in models of multifragmentation. Analyzing
two different mechanisms, the bond-percolation and the ERW (Elattari, Richert
and Wagner) statistical fragmentation models, we point out a common
quasi-gaussian shape of the total multiplicity distribution in the critical
range. The fixed-point property is also observed for the multiplicity of the
second bin. Fluctuations are studied using scaled factorial cumulants instead
of scaled factorial moments. The second-order cumulant displays the
intermittency signal while higher order cumulants are equal to zero, revealing
a large information redundancy in scaled factorial moments. A practical
criterion is proposed to identify the gaussian feature of light-fragment
production, distinguishing between a self-similarity mechanism (ERW) and the
superposition of independent sources (percolation).Comment: 20 pages, uuencoded .tex file including 16 figure
Scenario-based Economic Dispatch with Uncertain Demand Response
This paper introduces a new computational framework to account for
uncertainties in day-ahead electricity market clearing process in the presence
of demand response providers. A central challenge when dealing with many demand
response providers is the uncertainty of its realization. In this paper, a new
economic dispatch framework that is based on the recent theoretical development
of the scenario approach is introduced. By removing samples from a finite
uncertainty set, this approach improves dispatch performance while guaranteeing
a quantifiable risk level with respect to the probability of violating the
constraints. The theoretical bound on the level of risk is shown to be a
function of the number of scenarios removed. This is appealing to the system
operator for the following reasons: (1) the improvement of performance comes at
the cost of a quantifiable level of violation probability in the constraints;
(2) the violation upper bound does not depend on the probability distribution
assumption of the uncertainty in demand response. Numerical simulations on (1)
3-bus and (2) IEEE 14-bus system (3) IEEE 118-bus system suggest that this
approach could be a promising alternative in future electricity markets with
multiple demand response providers
Experimental Signals of Phase Transition
The connection between the thermodynamics of charged finite nuclear systems
and the asymptotically measured partitions is presented. Some open questions,
concerning in particular equilibrium partitions are discussed. We show a
detailed comparison of the decay patterns in Au+ C,Cu,Au central collisions and
in Au quasi-projectile events. Observation of abnormally large fluctuations in
carefully selected samples of data is reported as an indication of a first
order phase transition (negative heat capacity) in the nuclear equation of
state.Comment: 8 pages, 8th International Conference on Nucleus-Nucleus Collisions,
Moscow 200
Developing the Technique of Measurements of Magnetic Field in the CMS Steel Yoke Elements With Flux-Loops and Hall Probes
Compact muon solenoid (CMS) is a general-purpose detector designed to run at
the highest luminosity at the CERN large hadron collider (LHC). Its distinctive
features include a 4 T superconducting solenoid with 6 m diameter by 12.5 m
long free bore, enclosed inside a 10000-ton return yoke made of construction
steel. Accurate characterization of the magnetic field everywhere in
theCMSdetector, including the large ferromagnetic parts of the yoke, is
required. To measure the field in and around ferromagnetic parts, a set of
flux-loops and Hall probe sensors will be installed on several of the steel
pieces. Fast discharges of the solenoid during system commissioning tests will
be used to induce voltages in the flux-loops that can be integrated to measure
the flux in the steel at full excitation of the solenoid. The Hall sensors will
give supplementary information on the axial magnetic field and permit
estimation of the remanent field in the steel after the fast discharge. An
experimental R&D program has been undertaken, using a test flux-loop, two Hall
sensors, and sample disks made from the same construction steel used for the
CMS magnet yoke. A sample disc, assembled with the test flux-loop and the Hall
sensors, was inserted between the pole tips of a dipole electromagnet equipped
with a computer-controlled power supply to measure the excitation of the steel
from full saturation to zero field. The results of the measurements are
presented and discussed.Comment: 6 pages, 8 figures, 6 reference
An Impulse-Regime Switching Game Model of Vertical Competition
We study a new kind of non-zero-sum stochastic differential game with mixed impulse/switching controls, motivated by strategic competition in commodity markets. A representative upstream firm produces a commodity that is used by a representative downstream firm to produce a final consumption good. Both firms can influence the price of the commodity. By shutting down or increasing generation capacities, the upstream firm influences the price with impulses. By switching (or not) to a substitute, the downstream firm influences the drift of the commodity price process. We study the resulting impulse--regime switching game between the two firms, focusing on explicit threshold-type equilibria. Remarkably, this class of games naturally gives rise to multiple Nash equilibria, which we obtain via a verification based approach. We exhibit three types of equilibria depending on the ultimate number of switches by the downstream firm (zero, one or an infinite number of switches). We illustrate the diversification effect provided by vertical integration in the specific case of the crude oil market. Our analysis shows that the diversification gains strongly depend on the pass-through from the crude price to the gasoline price
Calculation of the number of partitions with constraints on the fragment size
This article introduces recursive relations allowing the calculation of the
number of partitions with constraints on the minimum and/or on the maximum
fragment size
The Multifragmentation Freeze--Out Volume in Heavy Ion Collisions
The reduced velocity correlation function for fragments from the reaction Fe
+ Au at 100 A~MeV bombarding energy is investigated using the
dynamical--statistical approach QMD+SMM and compared to experimental data to
extract the Freeze--Out volume assuming simultaneous multifragmentation.Comment: 8 pages; 3 uuencoded figures available with figures command, LateX,
UCRL-J-1157
digital surveys and 3d reconstructions for augmented accessibility of archaeological heritage
Abstract. This paper presents part of the results of a larger research project that focused on the surveying and documenting of Roman theatres and amphitheatres in the Campania region as well as the testing of a virtual fruition system for the digital reconstruction of a case study: the Roman theatre of Benevento. The work was carried out by the research group at the Interdepartmental Urban/Eco Research Centre of the University of Naples Federico II in collaboration with Spinvector, a company specialized in ICT – Information and Communication Technology – which lead to the defining of a fruition system of Cultural Heritage applied to archaeological heritage.The project included 3D digital surveys of the study samples carried out using reality-based techniques, which allowed for the acquisition of metric, morphological, geometric and colorimetric data. This made it possible to elaborate three-dimensional models, based on the current configuration of the places as well as of the possible original reconfigurations.</p
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