7,810 research outputs found

    Irreducible MultiQutrit Correlations in Greenberger-Horne-Zeilinger Type States

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    Following the idea of the continuity approach in [D. L. Zhou, Phys. Rev. Lett. 101, 180505 (2008)], we obtain the degrees of irreducible multi-party correlations in two families of nn-qutrit Greenberger-Horne-Zeilinger type states. For the pure states in one of the families, the irreducible 2-party, nn-party and (nm)(n-m)-party (0<m<n20< m < n-2) correlations are nonzero, which is different from the nn-qubit case. We also derive the correlation distributions in the nn-qutrit maximal slice state, which can be uniquely determined by its (n1)(n-1)-qutrit reduced density matrices among pure states. It is proved that there is no irreducible nn-qutrit correlation in the maximal slice state. This enlightens us to give a discussion about how to characterize the pure states with irreducible nn-party correlation in arbitrarily high-dimensional systems by the way of the continuity approach.Comment: 5p, no fi

    Formation time distribution of dark matter haloes: theories versus N-body simulations

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    This paper uses numerical simulations to test the formation time distribution of dark matter haloes predicted by the analytic excursion set approaches. The formation time distribution is closely linked to the conditional mass function and this test is therefore an indirect probe of this distribution. The excursion set models tested are the extended Press-Schechter (EPS) model, the ellipsoidal collapse (EC) model, and the non-spherical collapse boundary (NCB) model. Three sets of simulations (6 realizations) have been used to investigate the halo formation time distribution for halo masses ranging from dwarf-galaxy like haloes (M=103MM=10^{-3} M_*, where MM_* is the characteristic non-linear mass scale) to massive haloes of M=8.7MM=8.7 M_*. None of the models can match the simulation results at both high and low redshift. In particular, dark matter haloes formed generally earlier in our simulations than predicted by the EPS model. This discrepancy might help explain why semi-analytic models of galaxy formation, based on EPS merger trees, under-predict the number of high redshift galaxies compared with recent observations.Comment: 7 pages, 5 figures, accepted for publication in MNRA

    The distribution of ejected subhalos and its implication for halo assembly bias

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    Using a high-resolution cosmological NN-body simulation, we identify the ejected population of subhalos, which are halos at redshift z=0z=0 but were once contained in more massive `host' halos at high redshifts. The fraction of the ejected subhalos in the total halo population of the same mass ranges from 9% to 4% for halo masses from 1011\sim 10^{11} to \sim 10^{12}\msun. Most of the ejected subhalos are distributed within 4 times the virial radius of their hosts. These ejected subhalos have distinct velocity distribution around their hosts in comparison to normal halos. The number of subhalos ejected from a host of given mass increases with the assembly redshift of the host. Ejected subhalos in general reside in high-density regions, and have a much higher bias parameter than normal halos of the same mass. They also have earlier assembly times, so that they contribute to the assembly bias of dark matter halos seen in cosmological simulations. However, the assembly bias is {\it not} dominated by the ejected population, indicating that large-scale environmental effects on normal halos are the main source for the assembly bias.Comment: revised version, submitted to MNRA

    A novel overcurrent protection method based on wide area measurement in smart grid

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    PowerTech is the anchor conference of the IEEE Power & Energy Society in EuropeConventional overcurrent protection settings are fixed to detect faults. Power system operation mode varies while the settings of protection devices remain constant. As a result, overcurrent protection has a small protection range and a long operating time because it is incapable of adjusting its setting online. Wide Area Measurements System (WAMS) provides synchronized and real time data which can be utilized in new protection devices. This paper proposes a novel online setting scheme which utilizes online system data to calculate real-time system operation mode. Based on the real-time operation mode, real-time fault current is calculated before fault occurring. Settings of the protection devices are by this means adjusted in real time to expand the protection area and shorten the operating time. The calculation is expanded from single source model to multi-source with Π model. In addition, interval time of settings adjustment Tchange is proposed and calculated by using hyperbolic function model. Based on this method, power system real-time operation condition can be better monitored and the real-time short circuit current can be obtained to improve protection performance. © 2013 IEEE.published_or_final_versio

    Quantum entropy of the Kerr black hole arising from gravitational perturbation

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    The quantum entropy of the Kerr black hole arising from gravitational perturbation is investigated by using Null tetrad and \'t Hooft\'s brick-wall model. It is shown that effect of the graviton\'s spins on the subleading correction is dependent of the square of the spins and the angular momentum per unit mass of the black hole, and contribution of the logarithmic term to the entropy will be positive, zero, and negative for different value of a/r+a/r_+.Comment: 8 pages, 1 figure, Latex. to appear in Phys. Rev.

    ChatHuman: Language-driven 3D Human Understanding with Retrieval-Augmented Tool Reasoning

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    Numerous methods have been proposed to detect, estimate, and analyze properties of people in images, including the estimation of 3D pose, shape, contact, human-object interaction, emotion, and more. Each of these methods works in isolation instead of synergistically. Here we address this problem and build a language-driven human understanding system -- ChatHuman, which combines and integrates the skills of many different methods. To do so, we finetune a Large Language Model (LLM) to select and use a wide variety of existing tools in response to user inputs. In doing so, ChatHuman is able to combine information from multiple tools to solve problems more accurately than the individual tools themselves and to leverage tool output to improve its ability to reason about humans. The novel features of ChatHuman include leveraging academic publications to guide the application of 3D human-related tools, employing a retrieval-augmented generation model to generate in-context-learning examples for handling new tools, and discriminating and integrating tool results to enhance 3D human understanding. Our experiments show that ChatHuman outperforms existing models in both tool selection accuracy and performance across multiple 3D human-related tasks. ChatHuman is a step towards consolidating diverse methods for human analysis into a single, powerful, system for 3D human reasoning.Comment: Project page: https://chathuman.github.i

    The influence of baryons on the mass distribution of dark matter halos

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    Using a set of high-resolution N-body/SPH cosmological simulations with identical initial conditions but run with different numerical setups, we investigate the influence of baryonic matter on the mass distribution of dark halos when radiative cooling is NOT included. We compare the concentration parameters of about 400 massive halos with virial mass from 101310^{13} \Msun to 7.1×10147.1 \times 10^{14} \Msun. We find that the concentration parameters for the total mass and dark matter distributions in non radiative simulations are on average larger by ~3% and 10% than those in a pure dark matter simulation. Our results indicate that the total mass density profile is little affected by a hot gas component in the simulations. After carefully excluding the effects of resolutions and spurious two-body heating between dark matter and gas particles, we conclude that the increase of the dark matter concentration parameters is due to interactions between baryons and dark matter. We demonstrate this with the aid of idealized simulations of two-body mergers. The results of individual halos simulated with different mass resolutions show that the gas profiles of densities, temperature and entropy are subjects of mass resolution of SPH particles. In particular, we find that in the inner parts of halos, as the SPH resolution increases the gas density becomes higher but both the entropy and temperature decrease.Comment: 8 pages, 6 figures, 1 table, ApJ in press (v652n1); updated to match with the being published versio
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