Comparative Analysis of Methods for Assessing Adhesion Strength of Thermal Spray Coatings

The paper presents the comparative analysis of existing methods for accessing the adhesive strength of thermally sprayed coatings on witness samples and products in research and industrial laboratories. The adhesive method of normal separation for cylindrical witness samples with a diameter of 25 mm, a height of 16...45 mm and a coating thickness of at least 0.2 mm is pointed out among the quantitative approaches described in both international and domestic standards. An alternative pin test having no restrictions on the ultimate strength of adhesion was used to evaluate conical witness samples with an end section diameter of 1.5...2.0 mm and a coating thickness of 0.3...0.5 mm. The shear method presents two possible adhesion measurement tests: with cylindrical witness samples having the diameter of 25 mm, the width of the annular coating section of 4 ... 30 mm and the thickness of the working layer not exceeding 0.1 mm and prismatic ones with linear dimensions of shear section of 2.5...5.0 mm and the coating thickness of at least 0.25 mm. During the tests all methods were characterized by irregular loading of the flat section of the coating. Mathematical models for calculating the actual value of the tensile and shear adhesion strength are presented, taking into account the appearance of additional bending and shear forces when loading the coating.

Application of block-discretization method for analysis of electrical conductivity of graphene-containing shungite.

The block-discretization method for calculation of electrical conductivity of graphene-contained shungite is proposed and realized in practice. It is established that in the basis of forming of shungite carbon conductivity is presented the structure and arrangement of graphene packets which may be investigated only by electron microscopy method. The card of space allocation of graphene packets on the flat section of shungite specimen is brought. It is found two varieties of graphene packets distribution – regular when packets forms the ribbons one after the other and irregular when the packets are oriented in arbitrary directions. As a result of this cards character it is proposed to distinguish two varieties of observed structure – power-contrast which is formed by regulated ribbons and weak-contrast which is formed by chaotic oriented graphene packets. On the basis of model of current-tubes the valuing of electrical resistance for both kinds of structure is made. As a maximum cases for conditions of current flow it is investigated two orientation of packets inside of tube – suitable when the layers of graphene are oriented along the axis of tube and unsuitable when the layers of graphene are oriented across the axis of tube. In this case it is taken into account that the resistance of graphene packet across the layer is more then the resistance of its layer along the plane on three orders and more. It is found that the main resistance of tube is formed not only by graphene layers but in the most influence of joint from neighbouring graphene packets. The method of making of contour card which consist of the construction of boundaries between two kinds of structure and tracing the contour lines which correspond to individual ribbons in these boundaries is proposed. From the consideration of cards of flat section of structure it is established that the arrangement of packets, its orientation and conditions of grouping in general have same character in different parts of whole card. It is established that the extracted from the whole structure sufficient small area has the same specific conductivity as the whole structure. For the analysis of whole structure the method of block-discretization is proposed. This method consist of the breaking the whole massif on parts which are sufficiently similar to each other and analysis of several parts with subsequent averaging. It is supposed that the parameters of this averaged part may be calculated using simple means. After these actions the received meanings of parameters are repeated so times as it is necessary and as a result it is found the parameters of whole structure. The detailed step-by-step algorithm of using block-discretization method for the founding the specific conductivity of whole structure using the contour card of flat section of specimen is proposed. As a procedure of discretization it is proposed the breaking of whole card on square parts which are named as “blocks”. After this breaking from the different localizations from whole card it is chooses several blocks which parameters are subjected to averaging. After these actions it is constructed the net which is the same as initial net on the whole card but in this case the cells of this net are filled by equal averaged blocks. The calculation of parameters of whole card which consist of equal blocks gives the parameters of initial task. The application of block-discretization method is considered on the example of real shungite specimen from the deposit Nigozero which structure contains the ribbons intermitted by unregulated packets. It is constructed the contour card of specimen part having dimensions 40 x 40 nm. On this card is applied the net with square cells having dimension 10 x 10 nm which breaks the whole card into 16 blocks. It is made the secondary block discretization of blocks so as on the each block applied the net having cells 1 x 1 nm. Using this net the areas of block which contain the ribbons and unregulated packets and also the length and quantity of ribbons in block are found. The results of these measuring are averaged above all blocks. On the basis of averaged values of block parameters the geometrical structure of averaged block is constructed. It is found that the block may be presented as the closely packed on the flat of structure which consist of the equal single current tubes. In this case equal single tube consist of two successive connected parts. The first of these parts correspond to suitable orientation of grapheme packets and the second correspond to unsuitable orientation of the same packets. Using the received by electron microscopy methods parameters of grapheme layers and packets and also the gaps between its the resistance of single tube and averaged block consisted of these tubes is calculated. In supposition that the shungite structure is uniform in three axis on the basis of single tube and averaged block parameters the specific conductivity of carbon part of shungite is calculated. It is found that the obtained value of specific conductivity in comparison of specific conductivity of real shungite containing 97% carbon is larger approximate in three-four times. It is proposed the optimization of model by consideration into account the gap between packets and volume distribution of tubes in isotropic structure. These additions allows to obtain the good agreement between received data and meanings of conductivity of real shungites. In briefly mentioned some possibilities of development this work, mentioned the universal character of block-discretization method and mentioned some possible tasks for its application.

Approximation and the point of flicker-noise formation

The article refers to the field of research of noise fluctuations or flicker noise in electronic amplifiers and is devoted to the exact definition of the magnitude and shape of the spectral density of flicker-noise. The 1/f approximation of flicker noise is analyzed and the problem of its non-constructiveness in analyzing the noise characteristics of electronic amplifiers is shown. To eliminate this problem, the mechanism of physical formation of the envelope, a form of spectral density flicker-noise is defined. The physics of flicker-noise is detailed by accurate definition of the place of its formation. An accurate definition of the maximum difference of the amplifier flickernoise on the flat section of noise characteristics is given, using an explanation of the physics of flicker noise. The mechanism and conditions of the exponential increase of flicker noise and its subsequent exponential desire for maximum magnitude are explained. A simple physical approximation is given to determine the processes of forming the envelope form of the spectral density of flickernoise. The physical understanding of the formation of spectral density of flicker-noise tension in the internal structure of the transistor with the participation of external circuits of the amplifier electrical circuit is detailed. The results of the study will help developers to solve many problems of building electronic devices and optimizing their characteristics at a qualitatively new level.

Clusters of Chemical Compounds as Polytopes of the Highest Dimension

General analytical expressions are obtained for calculating the dimension of multi-shell clusters with a common center of shells in those cases when there is a metal atom in the center of the shells and when it is not. The shells can be in the shape of any body of Plato. It has been established that the gamma-copper cluster has the form of a cross-polytope of high dimension. The forms of clusters with ligands of the core of which is a chain of metal atoms or a metal polyhedron are geometrically investigated. It is shown that if the skeleton is a chain of metal atoms, then the cluster is polytope composed of two polytopes of higher dimension adjacent to each other along a flat section containing a chain. If the skeleton is a metal polyhedron, then a cluster of higher dimension has several ligand shells.

INFORMATION PROCESSING IN THE ASSISTING ROBOTECHNICAL SYSTEM: TRANSFORMATION AND VISUALIZATION

The article considers the development of software for information processing in an assisting robotic-technical system. The goal of the article is to synthesize a set of algorithms which allow transforming a digital cube in correspondence with its compression and stretching at any angle to the surface with a given force, as well as visualizing the transformation results in a volumetric form and any flat section. The paper describes the solution of several problems - generating 3D-image in the form of a digital cube with the possibility of its stratification along a discrete mesh. The authors also present the development of algorithms for transforming a digital cube. As a result, an assisting robotic system, a software module for transforming and visualizing the quasi-cube of a virtual object were designed and further development directions of the system were identified.

DESIGN AND VALIDATION OF A SURFACE PROFILING APPARATUS FOR AGRICULTURAL TERRAIN ROUGHNESS MEASUREMENTS

How to accurately and efficiently measure the profiles of the terrain on which agricultural machines operate has been an ongoing research topic. In this study, a surface profiling apparatus (profiler) was developed to measure agricultural terrain profiles along parallel tracks. The profiler is mainly composed of sensor frames, an RTK-GNSS system (Real Time Kinematics-Global Navigation Satellite Systems), laser sensors, an Inertial Measurement Unit (IMU) sensor and a data acquisition system. Along with a full description of how the terrain profiles were produced, a methodology to compensate for the tractor motion was included in the sensor data analysis. In field profiling validation, two trapezoidal bumps with known dimensions were used to assess the ability of the terrain profiler to reproduce the vertical profiles of the bumps, resulting in root mean square error (RMSE) of 3.6-4.7 mm and 4.5-5.1 mm with profiling speeds of 1.02 and 2.56 km/h, respectively. In addition, a validation test was also conducted on an asphalt road by profiling a flat road with the measuring wheels of the profiler rolling on the flat section but with the tractor wheels driving over a trapezoidal bump to excite the tractor pitch and roll motion. The measured profiles then also exhibited a flat road, which showed the ability of the profiler to remove the tractor motion from the profiling measurements.

Four-year soil erosion rates in a running-mountain trail in eastern Iberian Peninsula

During the last decades, the use of mountain trails for running is more and more popular. New trails are opened to allow the runners to practice and compete. This form of human impact on the landscape is new as the new trails do not follow the conservation strategies in design and maintenance as traditional mountain trails constructed by farmers, shepherds and muleteers do. This impact of sport events in nature is not measured and we know little about this impact on vegetation, fauna and soils. We surveyed in September 2018 a trail that was opened in September 2014 and was used for four official mountain trail races, and for training by local runners. Our interviews with organizers and users show that 1054 runners passed during the competition days (4 races in 4 years) and over the 4-year period the trail was used approximately 43,800 times by a runner. We measured the current topography and calculated the soil lost. The results show extremely high erosion rates in the sloping terrain, with the highest rates in the north-facing slope, reaching up to 180.29 Mg ha-1 y-1, while in the flat section of the trail soil erosion rates are 107.56 Mg ha-1 y-1 and in the south-facing slope trail 128.93 Mg ha-1 y-1. Our study demonstrates that (i) soil erosion rates on trails can be easily estimated by measuring the deepest trail position enabling fast and cheap surveys; and (ii) that there is a need to establish conservation strategies on new trails to avoid non-sustainable soil losses in the Mediterranean mountains due to the sport activities such as the mountain trail races.

Assessment of altimetry using ground-based GPS data from the 88S Traverse, Antarctica, in support of ICESat-2

We conducted a 750 km kinematic GPS survey, referred to as the 88S Traverse, based out of South Pole Station, Antarctica, between December 2017 and January 2018. This ground-based survey was designed to validate spaceborne altimetry and airborne altimetry developed at NASA. The 88S Traverse intersects 20 % of the ICESat-2 satellite orbits on a route that has been flown by two different Operation IceBridge airborne laser altimeters: the Airborne Topographic Mapper (ATM; 26 October 2014) and the University of Alaska Fairbanks (UAF) Lidar (30 November and 3 December 2017). Here we present an overview of the ground-based GPS data quality and a quantitative assessment of the airborne laser altimetry over a flat section of the ice sheet interior. Results indicate that the GPS data are internally consistent (1.1±4.1 cm). Relative to the ground-based 88S Traverse data, the elevation biases for ATM and the UAF lidar range from −9.5 to 3.6 cm, while surface measurement precisions are equal to or better than 14.1 cm. These results suggest that the ground-based GPS data and airborne altimetry data are appropriate for the validation of ICESat-2 surface elevation data.

Assessment of altimetry using ground-based GPS data from the 88S Traverse, Antarctica, in support of ICESat-2

We conducted a 750 km kinematic GPS survey, referred to as the 88S Traverse, based out of South Pole Station, Antarctica between December 2017 and January 2018. This ground-based survey was designed to validate spaceborne altimetry and airborne altimetry developed at NASA. The 88S Traverse intersects 20 % of the ICESat-2 satellite orbits on a route that has been flown by 2 different Operation IceBridge airborne laser altimeters: the Airborne Topographic Mapper (ATM; 26 October 2014) and the University of Alaska, Fairbanks (UAF) Lidar (30 November and 3 December, 2017). Here we present an overview of the ground-based GPS data quality and a quantitative assessment of the airborne laser altimetry over a flat section of the ice-sheet interior. Results indicate that the GPS data are internally consistent (1.1 ± 4.1 cm). Relative to the ground-based 88S Traverse data, the elevation biases for ATM and the UAF Lidar range from −9.5 to 3.6 cm, while surface measurement precisions are equal to or better than 14.1 cm. These results suggest that the ground-based GPS data and airborne altimetry data are appropriate for the validation of ICESat-2 surface elevation data.