Size Of Structural Elements Research Articles

RESISTANCE OF FERRITE-PERLITE STEEL TUBING BRANCH PIPE METAL TO DESTRUCTION IN HYDROGEN SULFIDE MEDIUM

This paper discusses the problems of resistance of the metal of the tubing branch pipe (tubing) to the process of its destruction in a medium containing hydrogen sulfide and when exposed to external forces. A 73х73 tubing nozzle made of 38G2SFA steel was selected as the material for research. The tubing fragment was destroyed during production well operation. To establish the reasons for the failure of the tubing nozzle, a visual inspection was carried out, tests were performed to assess the hardness and mechanical properties, the microstructure and microtexture of the metal were analyzed using scanning electron microscopy (SEM) methods. To analyze the nature of the distribution of introduced defects, the mutual orientation of structural components and crystallographic texture, studies were carried out by the method electron backscatter diffraction (EBSD). Studies of the suspended branch pipe, which does not have chemical protection, showed that the cause of its destruction was hydrogen sulfide stress corrosion cracking (SSCC) as a result of hydrogen embrittlement and the action of external tensile forces exceeding the yield strength of the metal. It was established that as a result of the interaction of hydrogen sulfide of the distilled product with the metal of the branch pipe, hydrogen embrittlement of the material of the branch pipe occurred. The process of hydrogen embrittlement of the fragment was proved by detecting hydrogen blisters in the metal microstructure and establishing the process of coalescence of neighboring inclusions. In addition, the results of the test to measure the hardness of the metal along the wall thickness further supported the hypothesis of hydrogen embrittlement of the tubing. EBSD analysis showed that the threaded part of the branch pipe is characterized by a small size of structural elements and an increased density of introduced defects (geometrically necessary dislocations), which are a promising site for the deposition of molecular hydrogen. It is concluded that reaching the limit concentration of molecular hydrogen reduces the binding energy of metal atoms and this process initiates the formation of pores. It has been established that the development of cracks along large-angle grain boundaries is facilitated, and small-angle and coincidence site lattice (Σ3, Σ5, Σ11 and Σ13b) grain boundaries are active barriers to crack propagation. It has been shown that by optimizing the elemental composition of steel, controlling the microstructure, crystallographic texture, as well as the type and state of grain boundaries, new pipeline steels can be produced that are more resistant to SSCC.

Infrared Small Target Detection Based on Density Peak Search and Local Features

The detection of small infrared targets is still a challenging task and efficient and accurate detection plays a key role in modern infrared search and tracking military applications. However, small infrared targets are difficult to detect due to their weak brightness, small size and lack of shape, structure, texture, and other information elements. In this paper, we propose a target detection method. First, to address the problem that the proximity of targets to high-brightness clutter leads to missed detection of candidate targets, a Gaussian differential filtering preprocessed image is used to suppress high-brightness clutter. Second, a density-peaked global search method is used to determine the location of candidate targets in the preprocessed image. We then use local contrast to the candidate target points to enhance the gradient features and suppress background clutter. The Facet model is used to compute multidirectional gradient features at each point. A new efficient surrounding symmetric region partitioning scheme is constructed to capture the gradient characteristics of targets of different sizes in eight directions, followed by weighting the candidate target gradient characteristics using the standard deviation of the symmetric region difference. Finally, an adaptive threshold segmentation method is used to extract small targets. Experimental results show that the method proposed in this paper has better detection accuracy and robustness compared with other detection methods.

Dual channel and multi-scale adaptive morphological methods for infrared small targets

Infrared small target detection is a challenging task. Morphological operators with a single structural element size are easily affected by complex background noise, and the detection performance is easily affected by multi-scale background noise environments. In order to enhance the detection performance of infrared small targets, we propose a dual channel and multi-scale adaptive morphological method (DMAM), which consists of three stages. Stages 1 and 2 are mainly used to suppress background noise, while stage 3 is mainly used to enhance the small target area. The multi-scale adaptive morphological operator is used to enhance the algorithm’s adaptability to complex background environments, and in order to further eliminate background noise, we have set up a dual channel module. The experimental results indicate that this method has shown superiority in both quantitative and qualitative aspects in comparison methods, and the effectiveness of each stage and module has been demonstrated in ablation experiments. The code and data of the paper are placed in https://pan.baidu.com/s/19psdwJoh-0MpPD41g6N_rw.

Оценка эффективности применения микробиологического препарата при выращивании травосмеси Bromus inermis и Elymus fibrosus на малопригодных субстратах

Abstract. The purpose of the work was to evaluate the effect of the microbiological preparation BIOR-AV on the structure, morphological characteristics and productivity of the grass mixture of Bromus inermis Leyss. and Elymus fibrosus (Schrenk) Tzvelev during the reclamation of planned clay dumps. Methods. Studies of experimental and control crops planted in 3 replicates within an area of 25 m2 were carried out during the growing seasons of 2001–2010. Projective cover and above-ground phytomass were determined on survey plots of 0.5 × 0.5 m; in each option, at least 15 plots were laid out. The dynamics of the morphological structure of vegetative and generative shoots was analyzed, and an agrochemical analysis of the substrate was carried out. Results. The positive effect of using the microbiological preparation during accelerated reclamation of dumps without applying fertile soil on the height, weight and length of leaves of vegetative and generative shoots; the number and size of structural elements of the inflorescences of the tested cereals (the length of the inflorescence, the number of branches in the inflorescence, the number of flowers, the number of spikelets, the weight of the inflorescence), and the sowing qualities of the seeds has been established. An increase in the content of the main elements of mineral nutrition in the substrate with the addition of the microbiological preparation: total nitrogen (1.6 times), available phosphorus and potassium (2 times), humus (5 times), as well as an increase in pH values from acidic to slightly acidic was revealed. The scientific novelty of the work: for the first time, in the conditions of the Middle Urals, monitoring studies of the effectiveness of the microbiological preparation on the structure, morphological parameters and productivity of a grass mixture of B. inermis and E. fibrosus were carried out on unsuitable clay substrates.

Impact of drug load and polymer molecular weight on the 3D microstructure of printed tablets

This study investigates the influence of drug load and polymer molecular weight on the structure of tablets three-dimensionally (3D) printed from the binary mixture of prednisolone and hydroxypropyl methylcellulose (HPMC). Three different HPMC grades, (AFFINISOLTM HPMC HME 15LV, 90 Da (HPMC 15LV); 100LV, 180 Da (HPMC 100LV); 4M, 500 Da (HPMC 4M)), which are suitable for hot-melt extrusion (HME), were used in this study. HME was used to fabricate feedstock material, i.e., filaments, at the lowest possible extrusion temperature. Filaments of the three HPMC grades were prepared to contain 2.5, 5, 10 and 20 % (w/w) prednisolone. The thermal degradation of the filaments was studied with thermogravimetric analysis, while solid-state properties of the drug-loaded filaments were assessed with the use of X-ray powder diffraction. Prednisolone in the freshly extruded filaments was determined to be amorphous for drug loads up to 10%. It remained physically stable for at least 6 months of storage, except for the filament containing 10% drug with HPMC 15LV, where recrystallization of prednisolone was detected.Fused deposition modeling was utilized to print honeycomb-shaped tablets from the HME filaments of HPMC 15LV and 100LV. The structural characteristics of the tablets were evaluated using X-ray microcomputed tomography, specifically porosity and size of structural elements were investigated. The tablets printed from HPMC 15LV possessed in general lower total porosity and pores of smaller size than tablets printed from the HPMC 100LV. The studied drug loads were shown to have minor effect on the total porosity of the tablets, though the lower the drug load was, the higher the variance of porosity along the height of the tablet was observed. It was found that tablets printed with HPMC 15LV showed higher structural similarity with the virtually designed model than tablets printed from HPMC 100LV. These findings highlight the relevance of the drug load and polymer molecular weight on the microstructure and structural properties of 3D printed tablets.

Sustainable approaches to improve the resilience of modular buildings under wind loads

Prefabricated volumetric modular building (PVMB) technology is an emerging technology that can make the construction industry walk towards sustainability by reducing the emission of pollutants leading to various environmental impacts. However, the knowledge of the lateral behaviour of PVMBs is limited. This could lead to significant building failure in future, as the climate continues to change, it is expected that building performance will be affected. Thus, this research aims to study the resilience of PVMBs under changing wind loads and identify the most sustainable approach to improve resilience. A 25-storey case-study building was analysed with modifications added to increase its lateral stiffness. Three methods of increasing the resilience were used: (1) increasing the size of structural elements; (2) increasing the inter-component connection stiffness; and (3) introducing discrete diaphragms. The results showed that using chevron bracings of the same section size as X-bracings can maintain the same resilience against the wind while decreasing total bracing steel volume by 32%. Among the analysis cases, structures with concrete cores (CC) have the highest stiffness to withstand the increased wind loads. The building with CC at the centre can withstand a 100% higher serviceability wind speed (i.e. 74 ms−1) than building without modifications (i.e. 37 ms−1). At the same time, the building with CC on either side can withstand a 45% higher wind speed than building without modifications. Further considering the sustainability aspects, the environmental effects of global warming can be reduced by about 160% when fully modular buildings are constructed with recycled steel.

Influence of Induction Heat Treatment Conditions on the Properties of Coatings Formed by Electroplasma Spraying

Porous titanium coatings were formed on titanium samples by electroplasma spraying, followed by induction heat modification in an air atmosphere at a processing temperature of 650–1250°C and a duration of 120 and 300 s. The layers formed by electroplasma spraying consisted of grains 9.9±0.5 µm in size. The coating composition included TiO, Ti2O3, and TiO2 (anatase) oxides formed as a result of interaction between titanium and gaseous medium (residual air atmosphere) in the installation working volume. After low-temperature thermal modification, the size of structural elements increased to 12.5±0.4 µm. The pore size decreased from 12.9±0.2 to 7.5±0.3 µm at an inductor current of 7.6 kA, whereas the surface porosity remained at the level of 56–58%. The induction treatment of the coatings has led to an increase in the oxygen content in the coatings from 49.6±9.2 to 71.7±1.1 at % and the formation of an oxide layer on the surface, consisting of prismatic nanosized anatase and rutile crystals. High-temperature thermal modification has led to intensive growth and subsequent exfoliation of scale. Induction heat treatment has led to an increase in the microhardness of the coatings from 1530±55 to 1825±191 HV0.98. The hardness of plasma-sprayed and low-temperature modified coatings was 82–88 HRF. The highest value of this parameter was observed during high-temperature treatment, which amounted to 108–115 HRF; in this case, the coating cracked during indentation, which is associated with the formation of a rather thick scale layer. As a result of static processing, regression models have been determined that describe the effect of temperature and time of modification of electroplasma coatings on the size of structural elements (grains, pores) and coating hardness.

Simulation of fire exposure behavior to building structural elements using LISA FEA V.8.

The purpose of this work is to evaluate the most generally used techniques for measuring the thermal conductivity of concrete, as well as to consider the variables influencing the thermal conductivity of cement-based materials. Based on previous research indicating that the pattern of heat flow can be modeled in a numerical analysis program and provide a hue of coverage and differences in indoor temperature conditions, as well as the impact that occurs on several elements in the room, a heat simulation analysis was performed in this study due to a fire. The researchers in this study simulated the flow pattern from the temperature that occurred due to fire in a room measuring 4000x4000 mm with a wall thickness of 200 mm with Hebel/light brick material, floor plate thickness was 120 mm, and the size of the building column structural elements was 400x400 mm with the material reinforced concrete. According to the simulation results of a fire that occurred in the middle of the room with two conditions for installing hebel walls, namely covering the building structure columns and those behind the building structure columns, there is an increase in the temperature of the column with a ratio of 1.062 in the two conditions where the temperature of the wall lining the column is 6.28% lower than the temperature of the wall behind the column, while the heat flux magnitude that occurs is lower.

A probabilistic approach to lifetime design of offshore platforms

Offshore platforms are considered critical infrastructure as any disruption in their lifetime service can rapidly result in a great loss to arise. While these structures are often designed for their initial construction cost, it is worth considering a lifetime-based design so that both direct and indirect costs are involved in the design process. Here, a probabilistic-based approach to life-cycle-cost (LCC) analysis of offshore platforms is proposed. A fixed offshore platform is designed first based on the current design regulations and for a 100-year return period. For the effect of LCC on design optimization, the simultaneous effect of the wave, current, and wind merging are probabilistically considered. The structural elements are designed for five different models; one model based on the current design requirements and the rest for more than the requirements. The LCC of each model is accordingly determined. The results show that the code-based model is not optimal when is compared with a lifetime cost period; it is necessary to increase the size of structural elements by up to 10% to meet an optimum point. Results show that with a 5% increase in the initial cost, a decrease in the LCC up to about 46% is observed. The work presented here is to stimulate stakeholders to promote the LCC-based design of important structures to reduce lifetime costs.

Factors Influence on Electrophysical Parameters of the Composite Varistors

Purpose. Evaluation influence structural state polymer phase on the response voltage and coefficient nonlinearity of a multilayer varistor based on zinc oxide. Methodology. Zinc oxide consisted of 97% zinc oxide and 3% total oxides of Bi2O3, Co3O4, MnO2, B2O3, SbO3, ZrO2, Al2O3. At a temperature of 1573°K, the synthesis of semiconductor ceramics based on Zinc oxide was carried out. For composite of thermoplastic polymers and Zinc oxide, non-polar and polar polymers, high pressure polyethylene and polyvinylidene fluoride were used. The composites were obtained by hot pressing at the melting temperature of the polymer phase and a pressure of 15 MPa. After that, using silver paste, measuring electrodes 10 mm in diameter were applied to the surface of the synthesized samples, and then current–voltage characteristics were measured. Modification of composites under action of gas-discharge plasma was carried out in a special cell that creates a dielectric-gas-composite system. The structure of the composites was studied by X-ray diffraction analysis and IR spectroscopy. Findings. The obtained experimental results show that the size of the particles of the inorganic phase significantly affects the current-voltage characteristics of the composite varistor: at a given thickness of the composite varistor, the operation voltage decreases markedly, and the nonlinearity coefficient increases. Numerous experimental results obtained by us show that the impact of electric discharge plasma on the polymer Zinc oxide-composite leads to a significant change in the permittivity and the concentration of local levels at the interface of the composite. The results research showed that effect electrical plasma on the opening voltage depends on the polarity of polymer matrices. Moreover, plasma processing itself significantly changes the structure of the polymer phase at composite. Originality. The magnitude of the potential barrier at phase boundary is mainly determined by the volume fraction and size of the main structural element of ZnO ceramics. Changing the structural state of the polymer matrix allows the adjust response voltage and coefficient nonlinearity of volt-ampere characteristic of the multilayer varistor. Practical value. The discovered development of electron-ion processes at polymer phase of the varistor indicates the need to take into account change in its service characteristics from the duration and intensity of use. The result obtained has a certain practical significance, since it indicates not only the reason for the change in properties, but also the need to develop measures to increase the service life of the varistor.

Locking Mechanism for Connecting Elements of Non-Removable Formwork

Purpose of research. Locking mechanisms have been widely used to connect elements of vertical formwork structures consisting of metal frames and shields fixed to them. The purpose of the study is to develop the design of the locking mechanism for the elements of removable formwork, which has high technological characteristics. A patent search was conducted for existing design solutions to ensure the connection of elements of removable formwork. It has been revealed that the most common structures used in the locking mechanisms of removable formwork elements are rack-and-pinion structures. The analysis of existing structures is carried out, the shortcomings of existing devices are revealed. It is established that the existing designs of locking mechanisms for connecting elements of removable formwork have low manufacturability of individual elements. In this regard, in order to solve the research problem, the design of the locking mechanism was developed, which ensures the connection of the elements of the removable formwork. A distinctive feature of the application of the new design of the locking mechanism for connecting the elements of removable formwork is the use of a new design of the toothed rail, which is more technologically advanced in manufacturing, compared with existing designs. Another distinctive feature is the use of a wedge with smooth edges, which also increases the manufacturability of the construction of the device for connecting the elements of removable formwork. To achieve this goal, an analytical research method was applied. The use of the proposed design will increase the manufacturability of the manufacture of locking mechanisms for connecting elements of removable formwork. The proposed design of the locking mechanism for connecting the elements of removable formwork, developed as a result of the study, has design features related to operating conditions. These features will be considered as a result of further research.Methods. Simulation modeling methods were used to conduct the experiments.Results. The range of sizes of the main structural elements of the locking mechanism for connecting the elements of removable formwork, ensuring the operation of the device under the action of design loads, is determined.Conclusion. The results of the study showed that the existing designs of locking mechanisms for connecting elements of removable formwork have disadvantages, one of which is the low manufacturability of the devices. The design of the locking mechanism has been developed, which provides higher manufacturability. The proposed device can be used in construction to connect elements of fixed formwork.

Rats' liver morphological features under conditions of different supply with vitamins and minerals

The current practice of novel food safety assessment in the Russian Federation involves toxicological studies on the alimentary model of adaptation potential reduction of laboratory animals. Since vitamin and mineral deficiency can affect the size of structural elements of tissues, an objective estimation of the results obtained using this model is possible when determining the range of fluctuations of the studied morphometric parameters under conditions of different essential substances' supply, as well as under conditions of simulated toxic effects on the background of the corresponding supply. The purpose of the research was to investigate the morphological and morphometric features of the liver under the influence of reduced intake of vitamins and mineral elements in the combination with toxic effects of various nature, during growth and puberty of male Wistar rats. Material and methods. The article analyzed data of 4 model experiments on 140 animals that received semi-synthetic casein diet with different supply of vitamins B1, B2, B3, B6 and mineral elements Fe3+ and Mg2+, as well as data of 2 experiments on 180 animals with simulated toxic load of cadmium (Cd2+) salts and carbon tetrachloride. The animals were ~95 days old at the time of sampling, the duration of the experiments was ~65 days. For the analysis we used data on rats' body weight on the day of material sampling, absolute and relative liver weight, hepatocyte diameter, nucleus diameter and hepatocyte cytoplasm size in the central and peripheral zones of hepatic lobules. A total of 200 cells were analyzed in each group of animals. In accordance with the study design, all quantitative traits of the groups that received diets with an essential nutrient supply ranging from 75 to 2% were compared with the group that received a complete diet (100%). Results. Morphometric examination of hepatocytes revealed a linear decrease in the size of cell structural elements in the series of reducing the content of essential micronutrients in the diet. Under the conditions of 2-4% vitamin and mineral supply, cell and nucleus diameters as well as cytoplasm size were by ~16.8, 12.6 and 21.1% (p<0.05) lower respectively than in rats with optimal supply of these substances; under the conditions of 9-19% supply were by ~9.2, 9.7 and 8.7% lower (p<0.05); higher levels of supply caused reduction of hepatocyte, nucleus and cytoplasm sizes in a range not exceeding 5% (p>0.05). When comparing the size of hepatocytes of rats subjected to toxic load with the hepatocytes of rats referred to the reference standard, an increase in the size of hepatocytes under the action of carbon tetrachloride by 17.4% (p<0.05) on average and under the action of cadmium salts by 4.6% (p<0.05) was noted. Conclusion. Based on the analysis of liver morphological and morphometric studies' data, there were established sizes of hepatocytes structural elements in the rats kept on diets with decreasing supply with B group vitamins, iron and magnesium salts; the linear decrease in the sizes of structural elements of hepatocytes in the series of reduction of B group vitamins, iron and magnesium intake was revealed. Toxic exposures to carbon tetrachloride and cadmium salts against the background of a 19-30-75% supply with essential substances led to an increase in the hepatocytes size, the correlation between the degree of toxicant exposure and the supply level is not significant.

Моделювання деформування соляних структур внаслідок гравітаційної плавучості

We consider modeling and geophysical interpretation of the obtained results in the deforming process of the salt structures due to gravitational buoyancy (halokinesis). For solving this geophysical problem, we use variation finite element method of elastic problem resolving with calculation of heterogeneous rocks distribution into considering salt structures. We have defined that salt structures deforming amplitudes mainly depend on linear sizes (length and thickness) of the bottom parts of these structures. Decreasing of these parameters lead to noticeable drop of the press-strain state near the whole region of the salt structure (diapirs). Another hand forms and linear sizes of the top parts of the salt stocks influence only on the deforming of the local regions near these structure elements and don’t essentially influence on the whole region deforming around the stock. Quantity characteristics of linear sizes of the salt diapirs structural elements define the whole picture of the stress-strain state around these objects.

Structure Optimization of a Fe-Mn-Pd Alloy by Equal-Channel Angular Pressing for Biomedical Use.

In this work, a Fe-Mn-Pd alloy was produced by methods of equal channel angular pressing (ECAP) in order to obtain an alloy with a high rate of degradation for the development of biodegradable devices. Special efforts were made to the obtaining of an ultrafine-grained structure of alloys in a fully austenitic state at temperatures of 300 °C and 450 °C. Further investigation of its effect on the corrosion rate and mechanical properties was carried out. The formation of an austenitic structure with structural element sizes of 100-250 nm after deformation was confirmed by X-ray diffraction analysis. ECAP proved to be the reason for a significant increase in strength with maximum σUTS = 1669 MPa and σYS = 1577 MPa while maintaining satisfactory plasticity. The alloy degradation rate was investigated using the potentiodynamic polarization analysis. The corrosion rate of the alloy after ECAP (~1 mm/y) is higher than that of the coarse-grained state and significantly higher than that of annealed iron (~0.2 mm/y). ECAP in both modes did not impair the biocompatibility of the Fe-Mn-Pd alloy and the colonization of the sample surface by cells.

Microstructure and Mechanical Properties of β-Titanium Ti-15Mo Alloy Produced by Combined Processing including ECAP-Conform and Drawing

At present, researchers pay great attention to the development of metastable β-titanium alloys. A task of current importance is the enhancement of their strength and fatigue properties. An efficient method for increasing the strength of such alloys could be severe plastic deformation. The object of this study was a medical metastable β-titanium alloy Ti-15Mo (ASTM F2066). The alloy in the (α + β) state was for the first time deformed by combined processing, including equal channel angular pressing-conform and drawing. Such processing enabled the production of long-length rods with a length of 1500 mm. The aim of the work was to study the effect of the combined processing on the alloy's microstructure and mechanical properties. An ultrafine-grained structure with an average size of structural elements less than 100 nm was obtained. At the same time, high strength and ductility (σuts = 1590 MPa, δ = 10%) were achieved, which led to a record increase in the endurance limit (σ-1 = 710 MPa) under tension-compression terms.

Structural characterization and conformational dynamics of alpha-1 antitrypsin pathogenic variants causing alpha-1-antitrypsin deficiency.

Background: Alpha-1 antitrypsin deficiency (A1ATD) is a progressive lung disease caused by inherited pathogenic variants in the SERPINA1 gene. However, their actual role in maintenance of structural and functional characteristics of the corresponding α-1 anti-trypsin (A1AT) protein is not well characterized. Methods: The A1ATD causative SERPINA1 missense variants were initially collected from variant databases, and they were filtered based on their pathogenicity potential. Then, the tertiary protein models were constructed and the impact of individual variants on secondary structure, stability, protein-protein interactions, and molecular dynamic (MD) features of the A1AT protein was studied using diverse computational methods. Results: We identified that A1ATD linked SERPINA1 missense variants like F76S, S77F, L278P, E288V, G216C, and H358R are highly deleterious as per the consensual prediction scores of SIFT, PolyPhen, FATHMM, M-CAP and REVEL computational methods. All these variants were predicted to alter free energy dynamics and destabilize the A1AT protein. These variants were seen to cause minor structural drifts at residue level (RMSD = <2Å) of the protein. Interestingly, S77F and L278P variants subtly alter the size of secondary structural elements like beta pleated sheets and loops. The residue level fluctuations at 100ns simulation confirm the highly damaging structural consequences of all the six missense variants on the conformation dynamics of the A1AT protein. Moreover, these variants were also predicted to cause functional deformities by negatively impacting the binding energy of A1AT protein with NE ligand molecule. Conclusion: This study adds a new computational biology dimension to interpret the genotype-protein phenotype relationship between SERPINA1 pathogenic variants with its structural plasticity and functional behavior with NE ligand molecule contributing to the Alpha-1-antitrypsin deficiency. Our results support that A1ATD complications correlates with the conformational flexibility and its propensity of A1AT protein polymerization when misfolded.

Structure and Mechanical Properties of Titanium Processed by Twist Extrusion and Subsequent Rolling

The article considers one of the combined methods of severe plastic deformation (SPD), which includes twist extrusion (TE) and subsequent rolling. The use of combined forming methods is promising for industrial use. Titanium grade 1 was used as a material in the experiments. Rolling was carried out in three stages with a decrease in temperature from 350°C to 180°C for a number of passes with one heating. The accumulated strain degree was e = 4.6 at twist extrusion and e = 3 in rolling. Increasing the reduction per pass decreases the number of heatings and increases the efficiency of the rolling process in whole. At the same time, it is necessary to set the maximum processing modes at which recrystallization processes do not occur in the billet. When rolling, the deformation degree in one pass was taken in the range of 5–20% with an increase in successive passes. The use of such deformation degrees allowed reducing the grain size in titanium grade 1 significantly. Twist extrusion reduces the grain size to 300–500 nm. Subsequent rolling allowed reducing the size of structural elements to 50–100 nm and provided a significant increase in the mechanical characteristics of the billet material (up to 869 MPa) while maintaining satisfactory ductility (up to 11.6%). It was found that increasing the deformation degree in one pass up to 40% at cross-rolling and simultaneously increasing the temperature to 385°C led to a decrease in the UFG structure quality and reduced strength of the deformable material by starting the dynamic recrystallization process.

Development of Ultrafine–Grained and Nanostructured Bioinert Alloys Based on Titanium, Zirconium and Niobium and Their Microstructure, Mechanical and Biological Properties

For this paper, studies of the microstructure as well as the mechanical and biological properties of bioinert titanium, zirconium, and niobium alloys in their nanostructured (NS) and ultrafine-grained (UFG) states have been completed. The NS and UFG states were formed by a combined two-step method of severe plastic deformation (SPD), first with multidirectional forging (MDF) or pressing into a symmetrical channel (PSC) at a given temperature regime, and then subsequent multi-pass groove rolling (MPGR) at room temperature, with pre-recrystallization annealing. Annealing increased the plasticity of the alloys in the NS and UFG states without changing the grain size. The UFG structure, with an average size of structural elements of no more than 0.3 μm, was formed as a result of applying two-step SPD and annealing. This structure presented significant improvement in the mechanical characteristics of the alloys, in comparison with the alloys in the coarse-grained (CG) or small-grained (SG) states. At the same time, although the formation of the UFG structure leads to a significant increase in the yield strength and tensile strength of the alloys, their elastic modulus did not change. In terms of biocompatibility, the cultivation of MG-63 osteosarcoma cells on the polished and sandblasted substrates demonstrated high cell viability after 10 days and good cell adhesion to the surface.

Method for determining the sizes of structural elements and semi-empirical formula of thermal characteristics of solar dryers

By choosing the initial dimensions of flat solar collectors, and by measuring the temperature of the incoming and outgoing air from the collector, it is possible to determine the linear dimensions of the drying cabinet attached to the collector. It is also possible to establish the basic semi-empirical formulas for determining the thermal characteristics of solar dryers. This calculation method was applied to design and build a study of an indirect solar dryer with natural air convection for drying apricots.

Spectral invariants in ultra-high spatial resolution hyperspectral images

Current operational optical satellite-based Earth observation methods targeting at vegetation are optimised for the high- and medium-resolution satellites with pixels sizes starting at ten meters. This resolution is coarser than the typical size of a vegetation structural element, such as a tree crown, and much coarser that of scattering elements, such as leaves. For this reason, vegetation can be treated as a continuous medium and the variation in the local illumination conditions on individual leaves or tree crowns can be ignored. This does not hold anymore for very and ultra-high resolution imagery, obtained from new satellite systems or unmanned aerial vehicles, where individual tree crowns or even leaves can be discerned. We tested the applicability of the spectral invariant theory to this type of imagery for characterising the local illumination conditions on plant leaves using Monte Carlo ray tracing simulations. The simulations corroborated the direct link between the spectral invariant parameter ρ and the sunlit fraction of visible leaves, earlier alleged for hyperspectral remote sensing data based on mathematical considerations. The approach allowed us to separate the direct beam and multiple scattering irradiance components and provided intuitive interpretations of the recollision probability and canopy scattering coefficient computed for each image pixel.