446 research outputs found
Effective Lagrangian and Dynamical Symmetry Breaking in the SU(2)XU(1) NJL Model
Dynamical symmetry breaking and the formation of scalar condensates in the
SU(2)XU(1) Nambu-Jona-Lasinio model with two coupling constants has been
studied in the framework of the mean field approximation. The bosonization
procedures of the model are performed using the functional integration method.
The possibility of the spontaneous CP symmetry breaking in the model under
consideration has been shown. The mass spectrum of the bound states of
fermions, as well as the effective Lagrangian of interacting scalar and
pseudoscalar mesons are obtained.Comment: 7 pages, LaTeX. Minor correction
Method for loading cargo trucks using two-dimensional packing algorithms
The paper describes the method for optimization of loading cargo trucks using two-dimensional packing algorithms. The point of this method is to reduce loading cargo problem to two-dimensional packing problem. This problem can be solved by using of various algorithms. There is analysis of several algorithms that are most often used in practical calculations of objects distribution in 2D space in this paper. The object of this study is transport of the metal processing company and its products (cargo). PHP programming language, MySQL database, and Apache web server are used to create client application. The interface developed using HTML5, CSS and javascript. © 2019 IOP Publishing Ltd. All rights reserved.The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0006
Comparative analysis of order allocation methods and intelligent systems for effective download of production capacities of manufacturing enterprise
The article compares the planning systems of the enterprise, determines their opportunities to use simulation for the process of distribution of production orders. A comparative review of the methods used in production planning systems and the multi-agent approach in solving the problem of the allocation of production orders is carried out. The possibility of approaches in cases when it is impossible to perform production tasks within the established time frame is considered, as well as to effectively load the available capacities of the units. In case it is not possible to produce the necessary quantity to distribute the part to another, similar to the type of equipment used, but different from it by the quantity and production capacity of the unit. Transmission must be carried out under the condition of sufficient capacity in the subdivision. The results of theoretical and experimental studies are presented. In the process of work, we used the BPsim. MAS dynamic modeling system. An automated system with the possibility of using simulation for the allocation of production orders is considered. © 2019 IOP Publishing Ltd. All rights reserved.The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0006
Building nonparametric -body force fields using Gaussian process regression
Constructing a classical potential suited to simulate a given atomic system
is a remarkably difficult task. This chapter presents a framework under which
this problem can be tackled, based on the Bayesian construction of
nonparametric force fields of a given order using Gaussian process (GP) priors.
The formalism of GP regression is first reviewed, particularly in relation to
its application in learning local atomic energies and forces. For accurate
regression it is fundamental to incorporate prior knowledge into the GP kernel
function. To this end, this chapter details how properties of smoothness,
invariance and interaction order of a force field can be encoded into
corresponding kernel properties. A range of kernels is then proposed,
possessing all the required properties and an adjustable parameter
governing the interaction order modelled. The order best suited to describe
a given system can be found automatically within the Bayesian framework by
maximisation of the marginal likelihood. The procedure is first tested on a toy
model of known interaction and later applied to two real materials described at
the DFT level of accuracy. The models automatically selected for the two
materials were found to be in agreement with physical intuition. More in
general, it was found that lower order (simpler) models should be chosen when
the data are not sufficient to resolve more complex interactions. Low GPs
can be further sped up by orders of magnitude by constructing the corresponding
tabulated force field, here named "MFF".Comment: 31 pages, 11 figures, book chapte
Hierarchic Superposition Revisited
Many applications of automated deduction require reasoning in first-order
logic modulo background theories, in particular some form of integer
arithmetic. A major unsolved research challenge is to design theorem provers
that are "reasonably complete" even in the presence of free function symbols
ranging into a background theory sort. The hierarchic superposition calculus of
Bachmair, Ganzinger, and Waldmann already supports such symbols, but, as we
demonstrate, not optimally. This paper aims to rectify the situation by
introducing a novel form of clause abstraction, a core component in the
hierarchic superposition calculus for transforming clauses into a form needed
for internal operation. We argue for the benefits of the resulting calculus and
provide two new completeness results: one for the fragment where all
background-sorted terms are ground and another one for a special case of linear
(integer or rational) arithmetic as a background theory
Noncommutative Black-Body Radiation: Implications On Cosmic Microwave Background
Including loop corrections, black-body radiation in noncommutative space is
anisotropic. A direct implication of possible space noncommutativity on the
Cosmic Microwave Background map is argued.Comment: 11 pages, no figs., LaTeX, accepted for Europhys. Let
A Phylogenetic Analysis of HIV-1 Sequences in Kiev: Findings among Key Populations
BACKGROUND: The HIV epidemic in Ukraine has been driven by a rapid rise among people who inject drugs, but recent studies have shown an increase through sexual transmission. METHODS: Protease and RT sequences from 876 new HIV diagnoses (April 2013 - March 2015) in Kiev were linked to demographic data. We constructed phylogenetic trees for 794 subtype A1 and 64 subtype B sequences and identified factors associated with transmission clustering. Clusters were defined as ≥ 2 sequences, ≥ 80% local branch support and maximum genetic distance of all sequence pairs in the cluster ≤ 2.5%. Recent infection was determined through the LAg avidity EIA assay. Sequences were analysed for transmitted drug resistance (TDR) mutations. RESULTS: 30% of subtype A1 and 66% of subtype B sequences clustered. Large clusters (maximum 11 sequences) contained mixed risk groups. In univariate analysis, clustering was significantly associated with subtype B compared to A1 (OR 4.38 [95% CI 2.56-7.50]), risk group (OR 5.65 [3.27-9.75]) for men who have sex with men compared to heterosexual males, recent, compared to long-standing, infection (OR 2.72 [1.64-4.52]), reported sex work contact (OR 1.93 [1.07-3.47]) and younger age groups compared to age ≥36 (OR 1.83 [1.10-3.05] for age ≤25). Females were associated with lower odds of clustering than heterosexual males (OR 0.49 [0.31-0.77]). In multivariate analysis, risk group, subtype and age group were independently associated with clustering (p<0.001, p=0.007 and p=0.033). 18 sequences (2.1%) indicated evidence of TDR. CONCLUSIONS: Our findings suggest high levels of transmission and bridging between risk groups
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