Electromgnetic-gravitational cross-sections in external elctromagnetic fields

The classical processes: the conversion of photons into gravitons in the static electromagnetic fields are considered by using Feynman perturbation techniques. The differential cross sections are presented for the conversion in the electric field of the flat condesor and the magnetic field of the selenoid. A numerical evaluation shows that the cross sections may have the observable value in the present technical scenario.Comment: 11 pages, LATEX, no figure

Higgs-gauge boson interactions in the economical 3-3-1 model

Interactions among the standard model gauge bosons and scalar fields in the framework of SU(3)_C X SU(3)_L X U(1)_X gauge model with minimal (economical) Higgs content are presented. From these couplings, all scalar fields including the neutral scalar $h$ and the Goldstone bosons can be identified and their couplings with the usual gauge bosons such as the photon, the charged $W^\pm$ and the neutral $Z$, without any additional condition, are recovered. In the effective approximation, full content of scalar sector can be recognized. The CP-odd part of Goldstone associated with the neutral non-Hermitian bilepton gauge boson $G_{X^0}$ is decouple, while its CP-even counterpart has the mixing by the same way in the gauge boson sector. Masses of the new neutral Higgs boson $H^0_1$ and the neutral non-Hermitian bilepton $X^0$ are dependent on a coefficient of Higgs self-coupling ($\lambda_1$). Similarly, masses of the singly-charged Higgs boson $H_2^\pm$ and of the charged bilepton $Y^\pm$ are proportional through a coefficient of Higgs self-interaction ($\lambda_4$). The hadronic cross section for production of this Higgs boson at the LHC in the effective vector boson approximation is calculated. Numerical evaluation shows that the cross section can exceed 260 $fb$.Comment: 22 pages, 1 figure, submitted to Phys. Rev.

Electromagnetic detection of axions

Photon-to-axion conversions in the static electromagnetic fields are reconsidered in detail by using the Feynman diagram techniques. The differential cross sections are presented for the conversions in the presence of the electric field of the flat condenser as well as in the magnetic field of the solenoid. Based on our results a laboratory experiment for the production and the detection of the axions is described. This experiment will exploit the axion decay constant as well as the axion mass.Comment: 7 pages, latex, no figures, to appear in Phys. Lett.

Sediment dynamics in the lower Mekong River : transition from tidal river to estuary

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 120 (2015): 6363–6383, doi:10.1002/2015JC010754.A better understanding of flow and sediment dynamics in the lowermost portions of large-tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and suspended-sediment concentration were measured for 25 h at three cross sections in the tidal Song Hau distributary of the Mekong River, Vietnam. Two campaigns took place during comparatively high-seasonal and low-seasonal discharge, and estuarine conditions varied dramatically between them. The system transitioned from a tidal river with ephemeral presence of a salt wedge during high flow to a partially mixed estuary during low flow. The changing freshwater input, sediment sources, and estuarine characteristics resulted in seaward sediment export during high flow and landward import during low flow. The Dinh An channel of the Song Hau distributary exported sediment to the coast at a rate of about 1 t s−1 during high flow and imported sediment in a spatially varying manner at approximately 0.3 t s−1 during low flow. Scaling these values results in a yearly Mekong sediment discharge estimate about 65% smaller than a generally accepted estimate of 110 Mt yr−1, although the limited temporal and spatial nature of this study implies a relatively high degree of uncertainty for the new estimate. Fluvial advection of sediment was primarily responsible for the high-flow sediment export. Exchange-flow and tidal processes, including local resuspension, were principally responsible for the low-flow import. The resulting bed-sediment grain size was coarser and more variable during high flow and finer during low, and the residual flow patterns support the maintenance of mid-channel islands.Office of Naval Research Grant Numbers: N00014-12-1-0181 , N00014-13-1-0127 , N00014-13-1-0781, and National Defense Science and Engineering2016-03-2

Analysis of Viscoelastoplastic Behavior of Expanded Polystyrene under Compressive Loading: Experiments and Modeling

The use of expanded polystyrene (EPS) in road paving, where the soil exhibits special properties (for example, compressive soil), calls for the necessity of investigating the mechanical behavior of this material. In this work, a study of the EPS compressive behavior is presented. It is divided into two parts: experimental and modeling investigations. The experimental results show that the EPS global compression behavior is characterized by three stages. Analysis of the results shows that the density of EPS plays an important role. A phenomenological mechanical model is considered in order to simulate the EPS viscoelastoplastic behavior in the case of compressive loading. A numerical analysis has been made in order to describe the mechanical behavior of the EPS material. This investigation has revealed a good correlation with the experimental results.При использовании расширенного полистирена в случае прокладки дорог, когда почва имеет особые свойства (например, сжатое состояние), возникает необходимость изучения механических характеристик этого материала. В данной работе исследованы механические свойства расширенного полистирена при сжатии. Работа включает две части: экспериментальное исследование и моделирование. Экспериментальные данные показали, что поведение расширенного полистирена при сжатии характеризуется тремя стадиями. При анализе установлено, что плотность расширенного полистирена играет важную роль. Рассмотрена феноменологическая механическая модель для моделирования вязкоупругопластических свойств при сжатии. С помощью численного анализа описаны механические свойства, которые хорошо согласуются с полученными экспериментально.При використанні розширеного полістирену у випадку прокладання доріг, коли грунт має особливості (наприклад, стиснення), виникає необхідність у вивченні механічних характеристик цього матеріалу. У даній роботі досліджено механічні характеристики розширеного полістирену при стисненні. Робота складається з двох частин: експериментального дослідження і моделювання. Експериментальні дані свідчать, що поведінка розширеного полістирену при стисненні характеризується трьома стадіями. Аналіз показав, що щільність розширеного полістирену грає важливу роль. Розглянуто феноменологічну механічну модель для моделювання в'язкопружнопластичних властивостей при стисненні. За допомогою числового аналізу описано механічні характеристики, які добре узгоджуються з отриманими експериментально

On Non-Elitist Evolutionary Algorithms Optimizing Fitness Functions with a Plateau

We consider the expected runtime of non-elitist evolutionary algorithms (EAs), when they are applied to a family of fitness functions with a plateau of second-best fitness in a Hamming ball of radius r around a unique global optimum. On one hand, using the level-based theorems, we obtain polynomial upper bounds on the expected runtime for some modes of non-elitist EA based on unbiased mutation and the bitwise mutation in particular. On the other hand, we show that the EA with fitness proportionate selection is inefficient if the bitwise mutation is used with the standard settings of mutation probability.Comment: 14 pages, accepted for proceedings of Mathematical Optimization Theory and Operations Research (MOTOR 2020). arXiv admin note: text overlap with arXiv:1908.0868

Stacking-Order-Dependent Excitonic Properties Reveal Interlayer Interactions in Bulk ReS₂

Rhenium disulfide, a member of the transition metal dichalcogenide family of semiconducting materials, is unique among 2D van der Waals materials due to its anisotropy and, albeit weak, interlayer interactions, confining excitons within single atomic layers and leading to monolayer-like excitonic properties even in bulk crystals. While recent work has established the existence of two stacking modes in bulk, AA and AB, the influence of the different interlayer coupling on the excitonic properties has been poorly explored. Here, we use polarization-dependent optical measurements to elucidate the nature of excitons in AA and AB-stacked rhenium disulfide to obtain insight into the effect of interlayer interactions. We combine polarization-dependent Raman with low-temperature photoluminescence and reflection spectroscopy to show that, while the similar polarization dependence of both stacking orders indicates similar excitonic alignments within the crystal planes, differences in peak width, position, and degree of anisotropy reveal a different degree of interlayer coupling. DFT calculations confirm the very similar band structure of the two stacking orders while revealing a change of the spin-split states at the top of the valence band to possibly underlie their different exciton binding energies. These results suggest that the excitonic properties are largely determined by in-plane interactions, however, strongly modified by the interlayer coupling. These modifications are stronger than those in other 2D semiconductors, making ReS2 an excellent platform for investigating stacking as a tuning parameter for 2D materials. Furthermore, the optical anisotropy makes this material an interesting candidate for polarization-sensitive applications such as photodetectors and polarimetry.</p