103,161 research outputs found
PolFusion: un progetto per rispondere a questioni ancora aperte.
No full textIl progetto PolFusion in collaborazione con IKP (Institut für Kernphysik) del FZJ (Forschungs Zentrum Jülich) di Jülich-Germania, PNPI (Petersburg Nuclear Physics Institute) di Gatchina-Russia e il gruppo di Ferrara,
guidato da Ciullo G., si propone di approfondire le tematiche ancora aperte della fusione nucleare polarizzata e di comunicare
alle comunità coinvolte in tali tematiche gli sviluppi raggiunti a tale scopo dalla fisica nucleare polarizzata.
Le prospettive previsionali di notevole interesse per la fusione nucleare, non
filtrano in modo sufficiente nelle comunità coinvolte nello sviluppo di reattori a fusione.
Il progetto si spinge inoltre a investigare processi di fusione polarizzata ancora non verificati sperimentalmente e modi di produzione ed utilizzo di combustibile polarizzato per reattori di futura generazione scremati da neutroni.
Ci si propone di presentare lo stato dell'arte degli argomenti e dei progetti correlati alla fusione polarizzata
Polarized Fusion: An Idea More Than Thirty Years Old! What Are We Waiting For?
No full textThe present status of the fusion research is strictly connected to government
investments on the corresponding research projects like ITER, or the proposed
IGNITOR and DEMO reactors. The production of energy by nuclear fusion is a perfect
option that could give “breath” to the planet. Recent agreements on limiting the
global climate change and plans for our future life on the planet require the reduction
of energy production by carbon-based resources. But even the use of nuclear
resources by fission implicates a non negligible risk for our civilization, either by
disasters like in Chernobyl or in Fukushima, or by the release of the fission products
into environment. CO2 emissions into the atmosphere and the growing and developing
population urgently require to put more effort into fusion programs worldwide.
An additional option for any fusion program could be the use of polarized fuel. It
still requires intense effort on the development of the necessary technologies, but it
is a realistic option to increase the energy output of different types of fusion reactors
and to increase the cost efficiency. First of all we would like to give an overview on
the current situation in energy production and recent climate development. Secondly,
we would like to provide an introduction to the contents of this volume, devoted to
nuclear fusion using polarized fuels
Nuclear Fusion with Polarized Fuel
No full textThis book offers a detailed examination of the latest work on the potential of polarized fuel to realize the vision of energy production by nuclear fusion. It brings together contributions from nuclear physicists and fusion physicists with the aims of fostering exchange of information between the two communities, describing the current status in the field, and examining new ideas and projects under development.
It is evident that polarized fuel can offer huge improvements for the first generation of fusion reactors and open new technological possibilities for future generations, including neutron lean reactors, which could be the most popular and sustainable energy production option to avoid environmental problems. Nevertheless, many questions must be resolved before polarized fuel can be used for energy production in the different reactor types. Readers will find this book to be a stimulating source of information on the key issues. It is based on contributions from leading scientists delivered at the meetings “Nuclear Fusion with Polarized Nucleons” (Trento, November 2013) and “PolFusion” (Ferrara, July 2015)
Polarized Fusion. Can Polarization Help to Increase the Energy Output of Fusion Reactors?
No full textSince more than 60 years scientists are working on the idea to produce energy from
nuclear fusion of light particles like the Hydrogen isotopes. In the meantime, the
energy output of e.g. tokamak reactors was increased by five orders and modern
experiments like JET are approaching the border for energy production. The international
ITER collaboration is preparing the first fusion reactor that will produce
about ten times more energy, compared to the energy that is needed to run the
experiment. Today, the laser-induced inertial fusion reached the same level and
experiments at the National Ignition Facility (NIF) in California, USA, demonstrate
a ratio between produced and induced energy about one at the end of 2013.1
In parallel, it is discussed since 1970 to use nuclear polarized fuel to increase the
total cross sections of the different fusion reactions.2 The energy gain of fusion reactors
does not depend linearly on the total cross section. Depending on the different
concepts for nuclear fusion, magnetic confinement or inertial fusion, the energy gain
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is improved above average. M. Temporal et al. have shown, e.g., that the energy
gain of laser-induced inertial fusion might be increased by a factor four, or that
the necessary laser power can be reduced by 20 %, if the nuclear fuel was polarized
before.3 The downsized laser power will reduce the costs of the corresponding
project by a reasonable amount. In addition, the differential cross sections can be
modified so that it will be possible to focus the ejectiles, e.g. the neutrons, on special
wall areas. In a tokamak this can be used to concentrate the neutron flux to special
outer parts of the blanket, where the cooling can be improved and the neutrons be
used for Tritium production via the exothermic reaction 6Li+n → 4He+t.4 At the
same time, less cooling is needed for the inner parts of the blanket that allows to
bring the magnetic field coils closer to the fusion plasma. The increased magnetic
field in the plasma will increase the energy gain additionally. Another option of
polarized fuel is a new kind of plasma diagnostic inside a tokamak. In combination
with modern Nuclear Magnetic Resonance technologies (NMR) anisotropies in the
plasma can be measured to learn more about the different plasma mode
Il Contrasto di Ciullo d'Alcamo, ristampato secondo la lezione del cod. Vaticano 3793, con commenti e illustrazioni di Alessandro d'Ancona
No full textP. G. Il Contrasto di Ciullo d'Alcamo, ristampato secondo la lezione del cod. Vaticano 3793, con commenti e illustrazioni di Alessandro d'Ancona. In: Romania, tome 3 n°12, 1874. pp. 495-498
Energy-Aware Base Stations: The Effect of Planning, Management, and Femto Layers
No full textWe compare the performance of three base station management schemes on three different network topologies. In addition, we explore the effect of offloading traffic to heterogeneous femtocell layer upon energy savings taking into account the increase of base station switch-off time intervals. Fairness between mobile operator and femtocell owners is maintained since current femtocell technologies present flat power consumption curves with respect to served traffic. We model two different user-to-femtocell association rules in order to capture realistic and maximum gains from the heterogeneous network. To provide accurate findings and a holistic overview of the techniques, we explore a real urban district where channel estimations and power control are modeled using deterministic algorithms. Finally, we explore energy efficiency metrics that capture savings in the mobile network operator, the required watts per user and watts per bitrate. It is found that the newly established pseudo distributed management scheme is the most preferable solution for practical implementations and together with the femotcell layer the network can handle dynamic load control that is regarded as the basic element of future demand response programs
Internal gas target experiments at the LHC
No full textThe physics opportunities offered by a fixed-target program using the proton and lead-ion beams of the LHC is wide and exciting. The LHC beams can provide the most energetic fixed-target measurements by pp, pA, and PbA collisions at √sNN = 72–115 GeV probing unexplored regions of the kinematical plane, including the high-x region. In the case of an unpolarized target the physics rich ranges from QCD to astroparticle, while the polarized target option opens the ground to novel measurements of TMDs, thereby contributing with a complementary approach to the understanding of the dynamics of the quark-gluon interplay inside the nucleon up to the 3-dimensional description of the nucleons. Among the main LHC experiments LHCb is the most suitable to host a fixed gas target. A description of the ongoing fixed-target proposals aimed at having the first LHC unpolarized data in Run3 and polarized data in Run4 will be discussed
Peer-assisted VoD Systems: An Efficient Modeling Framework
No full textWe analyze a peer-assisted Video-on-Demand (VoD) system in which users contribute their upload bandwidth to the redistribution of a video that they are downloading or that they have cached locally. Our target is to characterize the additional bandwidth that servers must supply to immediately satisfy all requests to watch a given video. We develop an approximate fluid model to compute the required server bandwidth in the sequential delivery case, as well as in controlled nonsequential swarms. Our approach is able to capture several stochastic effects related to peer churn, upload bandwidth heterogeneity, and nonstationary traffic conditions, which have not been documented or analyzed before. Finally, we provide important hints for the design of efficient peer-assisted VoD systems under server capacity constraints
The electronic structure of titanium(IV)chloride and vanadium(IV)chloride by an MS-SCF-Xα method. Assignment of photoelectron and electronic spectra
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