6,815 research outputs found
Surface diffuseness correction in global mass formula
By taking into account the surface diffuseness correction for unstable
nuclei, the accuracy of the macroscopic-microscopic mass formula is further
improved. The rms deviation with respect to essentially all the available mass
data falls to 298 keV, crossing the 0.3 MeV accuracy threshold for the first
time within the mean-field framework. Considering the surface effect of the
symmetry potential which plays an important role in the evolution of the
"neutron skin" toward the "neutron halo" of nuclei approaching the neutron drip
line, we obtain an optimal value of the symmetry energy coefficient J=30.16
MeV. With an accuracy of 258 keV for all the available neutron separation
energies and of 237 keV for the alpha-decay Q-values of super-heavy nuclei, the
proposed mass formula is particularly important not only for the reliable
description of the r-process of nucleosynthesis but also for the study of the
synthesis of super-heavy nuclei.Comment: 2 figures, 2 tables, to appear in Phys. Lett.
Orbital density wave induced by electron-lattice coupling in orthorhombic iron pnictides
In this paper we explore the magnetic and orbital properties closely related
to a tetragonal-orthorhombic structural phase transition in iron pnictides
based on both two- and five-orbital Hubbard models. The electron-lattice
coupling, which interplays with electronic interaction, is self-consistently
treated. Our results reveal that the orbital polarization stabilizes the spin
density wave (SDW) order in both tetragonal and orthorhombic phases. However,
the ferro-orbital density wave (F-ODW) only occurs in the orthorhombic phase
rather than in the tetragonal one. Magnetic moments of Fe are small in the
intermediate Coulomb interaction region for the striped antiferromangnetic
phase in the realistic five orbital model. The anisotropic Fermi surface in the
SDW/ODW orthorhombic phase is well in agreement with the recent angle-resolved
photoemission spectroscopy experiments. These results suggest a scenario that
the magnetic phase transition is driven by the ODW order mainly arising from
the electron-lattice coupling.Comment: 21 pages, 10 figure
Sub-daily simulation of mountain flood processes based on the modified soil water assessment tool (SWAT) model
Floods not only provide a large amount of water resources, but they also cause serious disasters. Although there have been numerous hydrological studies on flood processes, most of these investigations were based on rainfall-type floods in plain areas. Few studies have examined high temporal resolution snowmelt floods in high-altitude mountainous areas. The Soil Water Assessment Tool (SWAT) model is a typical semi-distributed, hydrological model widely used in runoff and water quality simulations. The degree-day factor method used in SWAT utilizes only the average daily temperature as the criterion of snow melting and ignores the influence of accumulated temperature. Therefore, the influence of accumulated temperature on snowmelt was added by increasing the discriminating conditions of rain and snow, making that more suitable for the simulation of snowmelt processes in high-altitude mountainous areas. On the basis of the daily scale, the simulation of the flood process was modeled on an hourly scale. This research compared the results before and after the modification and revealed that the peak error decreased by 77% and the time error was reduced from +/- 11 h to +/- 1 h. This study provides an important reference for flood simulation and forecasting in mountainous areas
Generalized Coherent Point Drift With Multi-Variate Gaussian Distribution and Watson Distribution
This letter introduces a novel rigid point set registration (PSR) approach that accurately aligns the pre-operative space and the intra-operative space together in the scenario of computer-Assisted orthopedic surgery (CAOS). Motivated by considering anisotropic positional localization noise and utilizing undirected normal vectors in the point sets (PSs), the multi-variate Gaussian distribution and the Watson distribution are utilized to model positional and normal vectors' error distributions respectively. In the proposed approach, with the above probability distributions, the PSR problem is then formulated as a maximum likelihood estimation (MLE) problem and solved under the expectation maximization (EM) framework. Our contributions are three folds. First, the rigid registration problem of aligning generalized points with undirected normal vectors is formally formulated in a probabilistic manner. Second, the MLE problem is solved under the EM framework. Third, the gradients of associated objective functions with respect to desired parameters are computed and provided. Experimental results on both the human pelvis and femur models demonstrate the potential clinical values and that the proposed approach owns significantly improved performances compared with existing methods
A Model for Residential Building Energy Consumption Characteristics and Energy Demand: A Case in Chongqing
AbstractThis study adopts a bottom-up typical method to establish the microscopic model to simulate the urban residential building energy consumption. The model is composed of a three-hierarchy structure: a) the classification according to the climate; b) according to the energy use; c) according to the energy intensity. Based on the model, energy consumption of urban residential building in Chongqing is calculated as an example. The calculation results of the model and the actual energy consumption are compared and validated. The residential building energy consumption model can be used to analyze the energy consumption in the past years using the existing data, as well as the development trend of the related factors so that the appropriate energy saving measures can be selected properly
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