Towards a macroscopically consistent discrete method for granular materials: Delaunay strain-based formulation

We demonstrate that the Delaunay-based strain definition proposed by Bagi (Mech Mater 22:165–177, 1996) for granular media can be straightforwardly translated into a particle-based numerical method for continua. This method has a number of attractive features, including linear completeness and satisfaction of the patch test, exact conservation of linear and angular momenta in the absence of external forces and torques, and anti-symmetry of the gradient vectors for any two points not both on the boundary of the computational domain. The formulation in effect relies on nodal (particle) interpolation of the deformation gradient and is therefore inherently unstable. Drawing on the analogy with granular media, a pairwise interaction between particles is included to alleviate this issue. The underlying idea is to define a local, non-affine deformation of each bond or contact, and to introduce pairwise forces via a stored-energy functional expressed in terms of the corresponding local displacements. In this manner, a generalisation of the Ganzenmüller (Comput Methods Appl Mech Eng 286:87–106, 2015) hourglass stabilisation procedure to non-central forces is obtained. The performance of the method is demonstrated in a range of problems. This work can be considered a first step towards the development of a macroscopically consistent discrete method for granular materials.

Modeling the electron orbital in transition subatomic structure

As part of the well-known task about a motion of charged particle in central forces field, a certain parallelism for electronic distribution between the atomic and subatomic ''orbits'' can be established.In this conjuncture the ground state of muonium atom as in transition electron-nuclear structure is highlighted. Moreover, there is specifically nuclear solution of fine-structure constant which with a hyper-fine structure, like of the Lamb shift of hydrogen atom, is unambiguously associated.Such a special approach, in the terms of electric interaction, may serve as an extension to the existing meson-boson classification.In particular, some idea about a versatility of the Higgs mechanism in nuclear reactions put forward for consideration here.But it would be just spatial abstraction, where subatomic matter expands as into infinity. And what would be beyond the edge of the universe?

Constraints on Newtonian Interplanetary Point-Mass Interactions in Multicomponent Systems from the Symmetry of Their Cycles

Interplanetary interactions are the largest forces in our Solar System that disturb the planets from their elliptical orbits around the Sun, yet are weak (<10−3 Solar). Currently, these perturbations are computed in pairs using Hill’s model for steady-state, central forces between one circular and one elliptical ring of mass. However, forces between rings are not central. To represent interplanetary interactions, which are transient, time-dependent, and cyclical, we build upon Newton’s model of interacting point-mass pairs, focusing on circular orbits of the eight largest bodies. To probe general and evolutionary behavior, we present analytical and numerical models of the interplanetary forces and torques generated during the planetary interaction cycles. From symmetry, over a planetary interaction cycle, radial forces dominate while tangential forces average to zero. Our calculations show that orbital perturbations require millennia to quantify, but observations are only over ~165 years. Furthermore, these observations are compromised because they are predominantly made from Earth, whose geocenter occupies a complex, non-Keplerian orbit. Eccentricity and inclination data are reliable and suggest that interplanetary interactions have drawn orbital planes together while elongating the orbits of the two smallest planets. This finding is consistent with conservation principles governing the eight planets, which formed as a system and evolve as a system.

Сalculation methodology and determination of efforts in vault

Problem. In this article we offer the meth-odology of calculation, based on the idea of dismem-berment of vault on the separate archs of single width. It is recommended for the estimation of efforts in the designed and damaged vaults. Also offered a methods of calculation effort in serried vaults. As spatial inflexibility of cross vault below than inflexi-bility of serried vault, then it is necessary to execute the calculation of the cheek arch abstracted from the tray of cross vault also. If the outline of tray is exe-cuted on a circular curve, then it is possible to take methodology of calculation of archs with the outline of axis a curve as catenoid. Goal. The proposed methodology for calculating closed and cross vaults is also based on the idea of dividing the arch into separate arches of unit width. The results of studies of efforts and rational forms of arches of V.A. Kiselev [1]. Methodology. Calculation based on the idea of dismemberment of vault on the separate archs of single width. Recommended for the estimation of efforts in the designed and damaged vaults. A method over of calculation of dome is brought for determina-tion of effort in serried vaults. Results. At the choice of outline of axis of arch it is necessary aspires to that an axis, on possibility, coincided with the curve of pressure. Such outline of axis is rational, as there are only central forces of N in an arch. Flexion mo-ments M and transversal forces of Q are equal to the zero. The coincidence of axis of arch with the curve of pressure can be got for the three-hinged arch. For the statically undetermined arch of complete coinci-dence of axis with the curve of pressure attaining is impossible, so that the origin of flexion moments at any her outline is inevitable. Originality. The tech-nique based on the separation of flat elements from the spatial structure does not show the reserves of strength of the structure. Experience of long-term operation of vaulted structures designed or verified by calculation using similar methods [2], [9] shows caution and reliability. Practical value. The tech-nique is also suitable for assessing the strength of damaged vaults with collapsed corners or walms.

Influence of the stationary and perturbed state of the central force field on the fractal characteristics of the attractor

The paper states that the known algorithms for generating and constructing fractal sets can be significantly expanded through the family of new algorithms proposed by the authors. These algorithms are based on modelling the attractors of motion of a material point in the field N of central forces in a discrete formulation. When only one of these forces is accidentally switched on at any given time, the point attractor has a strictly fractal structure. It is shown that the perturbation of one or more of the N central forces leads to a change in the structure of the attractor. Thus, the areas of the attractor Dp , controlled by the perturbed forces, with an increase in the perturbation radius, evolve to the perturbation trajectory. For biharmonic perturbations, it is shown that these subsets belong to the inner region of the 2n–point. It has been established that for small values of the perturbation radius R the parameter n → ∞, and for large values of R the parameter n → 1. For the field of central forces in the form of matrices 2*2; 3*3; 5*5 the quantitative models n(2R/B; m) are constructed and their close correlation with the perturbation parameter R, the size of the side B of the square matrix of the field of central forces and the “gravitational” parameter m is shown. It is shown that the gnoseology of the proposed algorithms originates from the wellknown algorithm of M. Barnsley, but the physical and software components are significantly improved and developed. The proposed family of algorithms allows to expand the possibilities of generating original (exclusive) fractal sets up to ~ 1040… 1050 pieces. At the same time, it is possible to control the fractal dimension, porosity, specific gravity, aerodynamic and hydraulic resistance, noise, sound and thermal insulation properties, colour of individual subregions, etc. in a wide range of values. It is shown that a significant part of such fractal sets, especially those with a high degree of symmetry, can be useful for solving problems in the field of design, ergonomics and aesthetics, for decorating buildings, clothing, footwear, haberdashery, toys, as well as for creating puzzles, IQ-tests, etc.

Linguistic, psychological and epistemic vulnerability in asylum procedures: An interdisciplinary approach

This article analyzes three video-recorded asylum interviews, their written records and the corresponding decisions by the Finnish Immigration Service. The goal is to identify the causes and consequences of vulnerability in instances that are particularly important when assessing whether the asylum seeker has a well-grounded fear of persecution. A combination of linguistic, psychological and epistemic perspectives on vulnerability shows that these three dimensions are closely intertwined in asylum interviews. Linguistic vulnerability is linked for the most part to interpreting, whereas psychological vulnerability stems from the difficulty in recounting traumatic experiences. Both linguistic and psychological vulnerabilities are central forces that also lead to epistemic vulnerability. Epistemic vulnerability, we claim, gives rise to certain practices within the asylum procedure, which again represents the materialization of the discourses of reporting, truth and credibility.