Dynamical dark energy from extra dimensions

We consider multidimensional cosmological model with a higher-dimensional product manifold M = R x R^{d_0} x H^{d_1}/\Gamma where R^{d_0} is d_0-dimensional Ricci-flat external (our) space and H^{d_1}/\Gamma is d_1-dimensional compact hyperbolic internal space. M2-brane solution for this model has the stage of accelerating expansion of the external space. We apply this model to explain the late time acceleration of our Universe. Recent observational data (the Hubble parameter at the present time and the redshift when the deceleration parameter changes its sign) fix fully all free parameters of the model. As a result, we find that considered model has too big size of the internal space at the present time and variation of the effective four-dimensional fine structure constant strongly exceeds the observational limits.Comment: 5 pages, 3 figures, LaTex, a few remarks and reference adde

Integrable Multicomponent Perfect Fluid Multidimensional Cosmology II: Scalar Fields

We consider anisotropic cosmological models with an universe of dimension 4 or more, factorized into n>1 Ricci-flat spaces, containing an m-component perfect fluid of m non-interacting homogeneous minimally coupled scalar fields under special conditions. We describe the dynamics of the universe: It has a Kasner-like behaviour near the singularity and isotropizes during the expansion to infinity. Some of the considered models are integrable, and classical as well as quantum solutions are found. Some solutions produce inflation from "nothing". There exist classical asymptotically anti-de Sitter wormholes, and quantum wormholes with discrete spectrum.Comment: 28 pages, LaTeX, subm. to Gen. Rel. Gra

Woodworking facilities: Driving efficiency through Automation applied to major process steps

The investment scenario applied to forestry development analyzes the fundamental changes in the production structure, among other things. These changes refer to the priority development of the pulp and paper industry through the chain of large-scale woodworking facilities, where pulp, paper and cardboard manufacturing plants are the key links. Such facilities include sawmilling facilities, wood-processing factories, and timber factories. Those provide a significant economic benefit, so improving them is one of the top priorities. Considering this priority is the purpose of this article. The goal was achieved using common and scientific research methods, including mathematical modeling. Theoretical research resulted in three sets of formulas adapted for evaluating the pulpwood barking from theoretical findings on image recognition. © 2018 Authors

On new gravitational instantons describing creation of brane-worlds

By considering 5--dimensional cosmological models with a bulk filled with a pressureless scalar field; equivalently dust matter, and a negative cosmological constant, we have found a regular instantonic solution which is free from any singularity at the origin of the extra--coordinate. This instanton describes 5--dimensional asymptotically anti de Sitter wormhole, when the bulk has a topology R times S^4. Compactified brane-world instantons which are built up from such instantonic solution describe either a single brane or a string of branes. Their analytical continuation to the pseudo--Riemannian metric can give rise to either 4-dimensional inflating branes or solutions with the same dynamical behaviour for extra--dimension and branes, in addition to multitemporal solutions. Dust brane-world models with arbitrary dimensions (D >= 5) as well as other spatial topologies are also briefly discussed.Comment: 11 pages, 3 figures, LaTeX2e, accepted for publication in Classical and Quantum Gravit

СПОСОБ ПРОТИВОЭРОЗИОННОЙ ОБРАБОТКИ ПОЧВЫ

Water-retaining roughnesses (holes, non-continuous furrows, micro-lagoons) come into being on the field surface at its tillage. They prevent a backflow, an erosion on slope lands and improve moisture content the soil. However, in the last decades such methods of a soil tillage are not used and the equipment for them are not manufactured. The author offered a new method of soil tillge with strips interchange (subsoil tilled and with the vegetable remains which are covered by the soil) in which cutout spherical disks form water-retaining non-continuous furrows. For this purpose harrows with two-disk and three-disk sections were developed. Two-disk sections in a front row contain needle disks and one spherical, and in a back row - needle and cutout spherical ones, forming a stank in a furrow. Three-disk sections in a front row contain needle disks, and in a back row - two needle and cutout spherical ones. A furrow part limited to its stanks is 4-5 times longer than a stank. A nonmoldboard loosened strip is wider than a strip with the covered vegetable remains and a non-continuous furrow. However, the general width does not exceed 0.4 m. In case of conservation tillage by a harrow with two-disk sections with spaces between disks 180 and 250 mm and 10 cm deep spherical disk non-continuous furrows can save up 216 and 155 cub. m of water per 1 hectare, and with three-disk at the same spaces - 144 and 103.7 cub. m respectively. At a disk approach angle of 20 degrees and 14 cm deep disks the capacity of furrows increases by 1.6 times.Водоудерживающие неровности (лунки, прерывистые борозды, микролиманы), созданные на поверхности поля при его обработке, предотвращают сток, проявления эрозии на склоновых землях и улучшают влагообеспеченность почвы. Однако в последние десятилетия такие приемы почвообработки не применяют и технику для них не производят. Предложили новый способ обработки почвы с чередованием полос (безотвально разрыхленных и с заделанными в почву растительными остатками), в которых сферическими дисками с вырезом формируют водоудерживающие прерывистые борозды. Для выполнения этого способа разработали бороны с двухдисковыми и трехдисковыми секциями. Двухдисковые секции переднего ряда содержат игольчатые диски и один сферический, а заднего - игольчатый и сферический с вырезом, формирующий перемычку в борозде. Трехдисковые секции переднего ряда содержат игольчатые диски, а заднего ряда - два игольчатых и сферический с вырезом. Участок борозды, ограниченный ее перемычками, в 4-5 раз длиннее перемычки. Безотвально разрыхленная полоса шире полосы с заделанными растительными остатками и прерывистой бороздой. Однако общая ширина не превышает 0,4 м. При противоэрозионной обработке бороной с двухдисковыми секциями с интервалами между дисками 180 и 250 мм и заглублением сферических дисков на 10 см прерывистые борозды могут накопить 216 и 155 куб. м воды на 1 га, а с трехдисковыми при таких же интервалах - 144 и 103,7 куб. м соответственно. При угле атаки 20 градусов и заглублении дисков на 14 см вместимость борозд увеличивается в 1,6 раза

Slow-roll inflation in (R+R*4) gravity

We reconsider the toy-model of topological inflation, based on the R*4-modified gravity. By using its equivalence to the certain scalar-tensor gravity model in four space-time dimensions, we compute the inflaton scalar potential and investigate a possibility of inflation. We confirm the existence of the slow-roll inflation with an exit. However, the model suffers from the eta-problem that gives rise to the unacceptable value of the spectral index n_s of scalar perturbations.Comment: 12 pages, 3 figures, LaTeX, misprints corrected and references update

РАЗМЕЩЕНИЕ СФЕРИЧЕСКИХ ДИСКОВ ФРОНТАЛЬНЫХ БОРОН

Disk-type spherical working tools are widely used in soil-cultivating machines, where they serve as an element base for combined units and disk harrows, including the multi-row ones with disks on individual racks. The tools are used in the implementation of traditional technologies based on reversible plowing, with surface tillage after late-harvested predecessors, for example, corn, sunflower, and also in NO-TIL technologies. (Research purpose) To determine the arrangement of working tools on the disk harrow frame, which reduces the required number of disks and improves the quality of soil cultivation. (Materials and methods) The authors have analyzed the arrangement of disk harrow working tools and determined their rational arrangement and mutual positions in the rows, which increases the tillage width between adjacent soil strips, thus improving the completeness of soil shearing and loosening over the entire operating width with simultaneous decreasing of the required number of disks. (Results and discussion) The authors have determined the interrelated arrangement of disks in their rows, aimed at improving soil shearing, so that the number of strips tilled into a ridge by adjacent disks increases. It has been shown that the arrangement of working tools of the consecutive row determined by the orientation of the adjacent disks of the previous row, allows to economize one working tool for every 400 mm of its operating width when shearing the soil all the way across the entire width of the disk harrow. (Conclusions) It has been established that when soil is tilled with a disk and moved toward the already processed adjacent strip, the technological width of the disk coverage increases due to the deformation of soil tearing and shearing. The authors have proposed the arrangement order of spherical disks and their mutual orientation, which improves the quality of soil cultivation, the completeness of soil shearing along the entire operating width, and leads to a reduction in the number of disks.В почвообрабатывающих  машинах широко используют дисковые сферические рабочие органы, которые служат элементной базой комбинированных агрегатов и дисковых борон, в том числе многорядных с дисками на индивидуальных стойках. Орудия применяют при выполнении традиционной технологии на основе отвальной вспашки при мелкой обработке после поздно убранных предшественников, например, кукурузы, подсолнечника, а также в технологиях NO-TIL. (Цель исследования) Обосновать  размещение рабочих органов на раме дисковой бороны, обеспечивающее уменьшение необходимого количества дисков и повышение качества обработки почвы. (Материалы и методы) Выполнили анализ размещения дисковых рабочих органов бороны и выявили их рациональное расположение и взаимную ориентацию в рядах, увеличивающие ширину обработки смежных полос почвы, улучшающие полноту подрезания и рыхления пласта по всей ширине захвата при уменьшении необходимого количества дисков. (Результаты и обсуждение) Установили такое взаимное размещение дисков в их рядах, при котором улучшается сдвиг почвы, повышается количество полосок, обрабатываемых в свал смежными дисками. Показали, что размещение рабочих органов последующего ряда с учетом ориентации смежных дисков предыдущего позволяет при полном подрезании почвы по всей ширине захвата дисковой бороны экономить один рабочий орган на каждые 400 миллиметров  ширины ее захвата. (Выводы) Выявили, что при обработке почвы диском с перемещением ее в сторону уже обработанной смежной полосы технологическая ширина захвата диска увеличивается за счет проявления деформации отрыва и сдвига почвы. Предложили порядок расположения сферических дисков и их взаимную ориентацию, повышающие качество обработки почвы, полноту подрезания по всей ширине захвата, а также возможность уменьшения их количества

Hilbert space of wormholes

Wormhole boundary conditions for the Wheeler--DeWitt equation can be derived from the path integral formulation. It is proposed that the wormhole wave function must be square integrable in the maximal analytic extension of minisuperspace. Quantum wormholes can be invested with a Hilbert space structure, the inner product being naturally induced by the minisuperspace metric, in which the Wheeler--DeWitt operator is essentially self--adjoint. This provides us with a kind of probabilistic interpretation. In particular, giant wormholes will give extremely small contributions to any wormhole state. We also study the whole spectrum of the Wheeler--DeWitt operator and its role in the calculation of Green's functions and effective low energy interactions.Comment: 23 pages, 2 figures available upon request, REVTE