550 research outputs found
Structure of the hadron-quark mixed phase in protoneutron stars
We study the hadron-quark phase transition in the interior of hot
protoneutron stars, combining the Brueckner-Hartree-Fock approach for hadronic
matter with the MIT bag model or the Dyson-Schwinger model for quark matter. We
examine the structure of the mixed phase constructed according to different
prescriptions for the phase transition, and the resulting consequences for
stellar properties. We find important effects for the internal composition, but
only very small influence on the global stellar properties.Comment: 6 pages, 4 figure
GPU implementation of the Frenet Path Planner for embedded autonomous systems: A case study in the F1tenth scenario
Autonomous vehicles are increasingly utilized in safety-critical and time-sensitive settings like urban environments and competitive racing. Planning maneuvers ahead is pivotal in these scenarios, where the onboard compute platform determines the vehicle's future actions. This paper introduces an optimized implementation of the Frenet Path Planner, a renowned path planning algorithm, accelerated through GPU processing. Unlike existing methods, our approach expedites the entire algorithm, encompassing path generation and collision avoidance. We gauge the execution time of our implementation, showcasing significant enhancements over the CPU baseline (up to 22x of speedup). Furthermore, we assess the influence of different precision types (double, float, half) on trajectory accuracy, probing the balance between completion speed and computational precision. Moreover, we analyzed the impact on the execution time caused by the use of Nvidia Unified Memory and by the interference caused by other processes running on the same system. We also evaluate our implementation using the F1tenth simulator and in a real race scenario. The results position our implementation as a strong candidate for the new state-of-the-art implementation for the Frenet Path Planner algorithm
Optimized Local Path Planner Implementation for GPU-Accelerated Embedded Systems
Autonomous vehicles are latency-sensitive systems. The planning phase is a critical component of such systems, during which the in-vehicle compute platform is responsible for determining the future maneuvers that the vehicle will follow. In this paper, we present a GPU-accelerated optimized implementation of the Frenet Path Planner, a widely known path planning algorithm. Unlike the current state-of-the-art, our implementation accelerates the entire algorithm, including the path generation and collision avoidance phases. We measure the execution time of our implementation and demonstrate dramatic speedups compared to the CPU baseline implementation. Additionally, we evaluate the impact of different precision types (double, float, half) on trajectory errors to investigate the tradeoff between completion latencies and computation precision
Structure of hybrid protoneutron stars within the Nambu--Jona-Lasinio model
We investigate the structure of protoneutron stars (PNS) formed by hadronic
and quark matter in -equilibrium described by appropriate equations of
state (EOS). For the hadronic matter, we use a finite temperature EOS based on
the Brueckner-Bethe-Goldstone many-body theory, with realistic two- and
three-body forces. For the quark sector, we employ the Nambu--Jona-Lasinio
model. We find that the maximum allowed masses are comprised in a narrow range
around 1.8 solar masses, with a slight dependence on the temperature.
Metastable hybrid protoneutron stars are not found.Comment: 7 pages, 6 figures, revised version accepted for publication in Phys.
Rev.
The Operator Product Expansion, Non-perturbative Couplings and the Landau Pole: Lessons from the O(N) -Model
We obtain the operator product expansion of the self-energy in the O(N)
non-linear -model to all orders in the coupling and the large momentum,
and to next-to-leading order in 1/N. In the light of this result we discuss
recent suggestions that there may be additional power corrections from short
distances, associated with defining the coupling constant non-perturbatively.
The non-linear -model provides no evidence for such `non-standard'
power corrections. We also find that the OPE converges for sufficiently large
external momentum, presumably because there are no multi-particle thresholds at
arbitrarily high energies in the 1/N expansion.Comment: 13 pages, 3 figure
Hybrid protoneutron stars with the MIT bag model
We study the hadron-quark phase transition in the interior of protoneutron
stars. For the hadronic sector, we use a microscopic equation of state
involving nucleons and hyperons derived within the finite-temperature
Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and
three-body forces. For the description of quark matter, we employ the MIT bag
model both with a constant and a density-dependent bag parameter. We calculate
the structure of protostars with the equation of state comprising both phases
and find maximum masses below 1.6 solar masses. Metastable heavy hybrid
protostars are not found.Comment: 12 pages, 9 figures submitted to Phys. Rev.
Astrophysical constraints on the confining models : the Field Correlator Method
We explore the relevance of confinement in quark matter models for the
possible quark core of neutron stars. For the quark phase, we adopt the
equation of state (EoS) derived with the Field Correlator Method, extended to
the zero temperature limit. For the hadronic phase, we use the microscopic
Brueckner-Hartree-Fock many-body theory. We find that the currently adopted
value of the gluon condensate , which gives
a critical temperature , produces maximum masses which
are only marginally consistent with the observational limit, while larger
masses are possible if the gluon condensate is increased.Comment: 7 pages, 5 figure
Recent Developments of Photovoltaics Integrated with Battery Storage Systems and Related Feed-In Tariff Policies: A Review
The paper presents a review of the recent developments of photovoltaics integrated with battery storage systems (PV-BESs) and related to feed-in tariff policies. The integrated photovoltaic battery systems are separately discussed in the regulatory context of Germany, Italy, Spain, United Kingdom, Australia, and Greece; the attention of this paper is focused on those integrated systems subject to incentivisation policies such as feed-in tariff. Most of the contributions reported in this paper consider already existing incentive schemes; the remaining part of the contributions proposes interesting and novel feed-in tariff schemes. All the contributions provide an important resource for carrying out further research on a new era of incentive policies in order to promote storage technologies and integrated photovoltaic battery systems in smart grids and smart cities. Recent incentive policies adopted in Germany, Italy, Spain, and Australia are also discussed
Hadron-Quark Phase Transitions in Hyperon Stars
We compare the Gibbs and Maxwell constructions for the hadron-quark phase
transition in neutron and protoneutron stars, including interacting hyperons in
the confined phase. We find that the hyperon populations are suppressed, and
that neutrino trapping shifts the onset of the phase transition. The effects on
the (proto)neutron star maximum mass are explored.Comment: 11 pages, 3 figure
A renewable energy community of DC nanogrids for providing balancing services
The massive expansion of Distributed Energy Resources and schedulable loads have forced a variation of generation, transmission, and final usage of electricity towards the paradigm of Smart Communities microgrids and of Renewable Energy Communities. In the paper, the use of multiple DC microgrids for residential applications, i.e., the nanogrids, in order to compose and create a renewable energy community, is hypothesized. The DC Bus Signaling distributed control strategy for the power management of each individual nanogrid is applied to satisfy the power flow requests sent from an aggregator. It is important to underline that this is an adaptive control strategy, i.e., it is used when the nanogrid provides a service to the aggregator and when not. In addition, the value of the DC bus voltage of each nanogrid is communicated to the aggregator. In this way, the aggregator is aware of the regulation capacity that each nanogrid can provide and which flexible resources are used to provide this capacity. The effectiveness of the proposed control strategy is demonstrated via numerical experiments. The energy community considered in the paper consists of five nanogrids, interfaced to a common ML-LV substation. The nanogrids, equipped with a photovoltaic plant and a set of lithium-ion batteries, participate in the balancing service depending on its local generation and storage capacity. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
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