Electron Transport in Granular Metals

We consider thermodynamic and transport properties of a long granular array with strongly connected grains (inter-grain conductance g>>1.) We find that the system exhibits activated behavior of conductance and thermodynamic density of states ~exp(-T*/T) where the gap, T*, is parametrically larger than the energy at which conventional perturbation theory breaks down. The scale T* represents energy needed to create a long single-electron charge soliton propagating through the array.Comment: 4 pages, 1 figur

Vortex ordering in fully-frustrated superconducting systems with dice lattice

The structure and the degenracy of the ground state of a fully-frustrated XY-model are investigated for the case of a dice lattice geometry. The results are applicable for the description of Josephson junction arrays and thin superconducting wire networks in the external magnetic field providing half-integer number of flux quanta per plaquette. The mechanisms of disordering of vortex pattern in such systems are briefly discussed.Comment: 10 pages, 3 figure

Use of Glauconite in Potato Cultivation Technology

In intensive technologies of cultivation of potatoes, the need for trace elements is increasing. The concentration of trace elements in plants is very small, but the importance of these elements in biochemical processes is difficult to overestimate. The deficiency of trace elements is the root cause of many functional disorders. Trace elements in plants are part of enzymes, stimulate and accelerate plant development, increase resistance to adverse environmental conditions, etc. Also, with their shortage, crop productivity decreases. The use of natural minerals, such as glauconite, containing trace elements, allows improving comprehensive nutrition and increase productivity. Getting early production of high quality potatoes in the summer is important and relevant in the modern world. The use of glauconite in the conditions of the Moscow region, along with fertilizers and irrigation, allows obtaining high-quality products and increasing productivity by 6.3... 29.0%

The concept of aerial photography using a two-element active optoelectronic complex

The article proposes the concept of obtaining images on the basis of which it is possible to create three-dimensional models of objects. In particular, images contain the data necessary to recreate the three-dimensional form of an object. Such data include: the length, width of the modeled object as well as the lengthening of the shadow cast on the base surface. In accordance with the proposed concept, an important condition for obtaining images suitable for interpretation is the use of spatially separated equipment generating and recording optical radiation. The orientation parameters of the illumination source and the camera are selected, taking into account the requirements for the photogrammetric quality of images. A characteristic of geometric distortions that occur when changing the shooting mode from plan to perspective is presented, which demonstrates the change in the aspect ratio of the image depending on the angle of the camera. A characteristic of the shadow elongation depending on the spatial position of the optical radiation source is presented, which shows the influence of the orientation parameters of the optical illumination means on the length of the shadow cast on the base surface. On the basis of these characteristics, the choice of parameters of relative orientation in space of the source of optical illumination and the equipment that detects optical radiation is substantiated. Predicting the value of geometric distortions of images at the stage of choosing the parameters of relative orientation of the equipment of a two-element active optoelectronic complex allows you to save the photogrammetric quality of images and, as a result, measure the length and width of an object. Predicting the magnitude of the shadow elongation under conditions of artificial optical illumination provides the possibility of transferring features in the image for calculating the applicate and, as a result, recreating the three-dimensional shape of the object. The proposed concept of image registration finds application in topographic and geodetic and engineering work in conditions of insufficient natural light. For example, the use of a two-element active optical-electronic complex makes it possible to obtain three-dimensional photo plans of the terrain of geographic regions with a short daylight hours

The occurrence of ideal plastic state in CP titanium processed by twist extrusion

This paper deals with the analysis of strength and plastic characteristics of commercially pure (CP) titanium as a function of equivalent plastic strain accumulated during Twist Extrusion (TE) process. It is shown experimentally that multipass TE leads to the saturation of the following characteristics of the material: yield stress, reduction in area, elongation to failure, and uniform elongation. This fact indicates the occurrence of an ideal plastic state in the processed material. The threshold value of accumulated plastic strain for ideal plastic behavior of CP titanium during TE is defined. The strain state and mechanical properties of CP titanium billets processed by TE are studied. An explanation for the hardening on the axis of a billet during TE is offered. The analysis of deformation modes on the billet axis during TE and High Pressure Torsion is carried out. It is shown that the differences in strain state on the axis are caused by the difference in symmetry of these processes

Evaluation of the shear strength of rocks by cracks based on the results of testing samples with spherical indentors

Experimental data on the relationship of the residual shear strength of rocks in closed cracks with the functional characteristics of intact rocks – the tensile and compressive components of adhesion, the roughness of the crack surfaces, and the level of normal stresses are presented. A unified integrated approach determines the shear strength of intact and destroyed rocks, the residual shear strength of closed rough cracks has been developed. The approach provides for the selection of stress intervals corresponding to different types of fracture, for each of which a strength criterion is proposed, expressed in terms of functional characteristics of intact rock. An express method for estimating the residual shear strength of rocks by cracks with a rough surface has been developed, in which an improved method of loading samples with spherical indentors is used as a basic test method. The express method implements the transition from the data of mechanical tests of samples with spherical indentors to the shear strength indicators for cracks in the rock mass, taking into account the level of normal stresses and the roughness of the crack surfaces measured in field conditions. In this case the roughness scale developed by Barton is used. The express method is informative and available in the fieldwork

An approach to photogrammetric processing of indirect optical location data

The paper proposes an approach to obtaining images of the objects under investigation based on indirect optical location data. The goal of the study is to increase the graphic similarity of the images and to assign them measuring properties. To achieve this goal, the concept of photogrammetric processing of frame images obtained by conducting indirect optical location in a certain way is formulated. The graphical similarity of the images is proposed to be improved by extracting photometric data related to the object and the background from the registered optical radiation. Based on the selected data, a statistical evaluation of the sample average of the optical radiation intensity from these sources is carried out. The obtained estimates are used to form a monochrome digital image. Adding measurement properties is done by converting the coordinates of the digital image to relative coordinates that have a metric expression. The reason for the decrease in the graphical similarity of the images obtained on the basis of indirect optical location data is determined. In particular, the addition of light waves from different sources, during the allotted exposure time of the photodetector, leads to the merging of the object and the background in the resulting image. The paper presents an approach to the separation of photometric data from different sources that is based on the observation of the phase difference between the emitted and recorded light waves. The authors define the mathematical apparatus for linking the obtained images to the relative coordinate system that is adapted for the case of indirect optical location. The concept of conducting indirect optical location using a special optoelectronic complex is proposed. The study describes the requirements for the equipment of an optoelectronic complex that generates and registers optical radiation with the required parameters. The results of an experiment on the formation of images with measuring properties confirm the feasibility of using the proposed method. Conducting an indirect optical location opens the way to obtaining images of an area that is inaccessible to humans. In particular, the results of the experiment demonstrate that the use of the proposed concept provides images of an object placed behind a light-tight obstacle, which are characterized by the presence of measuring properties and reflect the details of the object under study with high graphical similarity

Structure of the superconducting state in a fully frustrated wire network with dice lattice geometry

The superconducting state in a fully frustrated wire network with the dice lattice geometry is investigated in the vicinity of the transition temperature. Using Abrikosov's variational procedure, we write the Ginzburg-Landau free energy functional projected on its unstable supspace as an effective model on the triangular lattice of sixfold coordinated sites. For this latter model, we obtain a large class of degenerate equilibrium configurations in one to one correspondence with those previously constructed for the pure XY model on the maximally frustrated dice lattice. The entropy of these states is proportional to the linear size of the system. Finally we show that magnetic interactions between currents provide a degeneracy lifting mechanism.Comment: The final version (as published in Phys. Rev. B). Substantial corrections have been made to Sec.

Nature of phase transition(s) in striped phase of triangular-lattice Ising antiferromagnet

Different scenarios of the fluctuation-induced disordering of the striped phase which is formed at low temperatures in the triangular-lattice Ising model with the antiferromagnetic interaction of nearest and next-to-nearest neighbors are analyzed and compared. The dominant mechanism of the disordering is related to the formation of a network of domain walls, which is characterized by an extensive number of zero modes and has to appear via the first-order phase transition. In principle, this first-order transition can be preceded by a continuous one, related to the spontaneous formation of double domain walls and a partial restoration of the broken symmetry, but the realization of such a scenario requires the fulfillment of rather special relations between the coupling constants.Comment: 10 pages, 7 figures, ReVTeX

Integrable Circular Brane Model and Coulomb Charging at Large Conduction

We study a model of 2D QFT with boundary interaction, in which two-component massless Bose field is constrained to a circle at the boundary. We argue that this model is integrable at two values of the topological angle, $\theta =0$ and $\theta=\pi$. For $\theta=0$ we propose exact partition function in terms of solutions of ordinary linear differential equation. The circular brane model is equivalent to the model of quantum Brownian dynamics commonly used in describing the Coulomb charging in quantum dots, in the limit of small dimensionless resistance $g_0$ of the tunneling contact. Our proposal translates to partition function of this model at integer charge.Comment: 20 pages, minor change