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The subject of the study is the process of active ventilation of wheat grain with variable heat supply. The purpose of the work is a mathematical description of the nature of the flows of matter and energy in the process of active ventilation of wheat grain. Thanks to the selected original design of the exhaust coolant outlet unit, made in the form of a mesh spiral tube, it was possible to optimize the hydrodynamic situation in the layer of dried grain. The developed mathematical model, as a mathematical description, consists of equations of material, thermal balances, equations of hydrodynamics in steady and unsteady states. This mathematical model is the basis for creating a material model of the process and conducting an experiment with subsequent data processing. As a result, it is possible to obtain criteria equations of processes that make it relatively easy to calculate processes under various technological modes.

Relevance. Lichenoindication is widely used to assess the quality of atmospheric air. For southwestern Crimea, the assessment of the state of atmospheric air based on licheninication data is carried out for the first time. The aim of the research is to assess the quality of atmospheric air in southwestern Crimea according to lichen detection data. The objects of the study are epiphytic lichens, Evernia prunastri, Ramalina farinacea, Physcia, Parmelia sulcata. Methods. For analysis in the period from February to May 2018, 17 samples of epiphytic fruticose lichens were taken in different landscape conditions (foothills, intermontane basins, mountain tops), taking into account different levels of anthropogenic load. The samples contain seven elements: Cu, Zn, Pb, Cd, Ni, Cr, Sr. The elemental composition of lichens was determined using an atomic absorption spectrometer. Results. It was revealed that the most actively accumulated metals in the lichens of southwestern Crimea are Zn, Sr and Pb; less active accumulation of Cu, Cd, Ni and Cr. The analysis showed that anthropogenic sources of pollution are to a greater extent induced by the content of Cu, Zn, Pb in lichens. The high Sr content is due to its ability to replace calcium in potassium-containing minerals in carbonate rocks, which are widespread in the region. The noted relatively high level of air pollution in the city of Inkerman is due to emissions from the Sevastopol combined heat and power plant, near the gas station on the Yalta–Sevastopol highway – emissions from vehicles, in rural settlements of the Baydarsky valley – emissions from coal burning with stove heating. It was revealed that the data on the content of heavy metals in lichens sampled in the Chernorechensky canyon can be considered a reference for determining the background parameters and the level of pollution of the surface atmosphere in other regions of southwestern Crimea. Lichens can be used to supplement the monitoring system for surface air pollution in southwestern Crimea during atmospheric transport.

Machines with pneumatic systems are used to clean grain from light impurities and dust. Modern grain cleaning machines for preliminary cleaning from light impurities and dust with a pneumatic system do not fully meet the increasing requirements of modern agricultural production in terms of their performance. The article presents the principle of operation and a mathematical description that allows you to determine the main parameters of the installation. In this work, an analytical research method was used based on the analysis of differential equations describing the processes of cleaning grain from light impurities and dust. To develop a mathematical model, the method of constructing Lagrange mathematical models was applied. On the basis of this model, a number of equations were constructed that characterize: the transition of the potential energy of the grain mass into the kinetic energy of the grain flow; dynamic equation of the equilibrium fall of the grain flow; the volume flow rate of the air flow in the intergranular space, as well as an equation that makes it possible to determine the pressure loss in the air flow passing through the blinds and the average speed of the grains falling. Taking into account the above equations, a mathematical model is built in the form of a system of equations. This mathematical model makes it possible to determine the main design parameters of the new installation: the geometric dimensions of the working area, as well as energy costs for the grain cleaning process. The introduction of the developed installation at the receiving points of the elevators makes it possible to increase the efficiency of grain cleaning from light impurities and dust at low unit costs.

The merging of the electronic structure calculations and crossed beam experiments expose the reaction dynamics in the tin (Sn, 3Pj) − molecular oxygen (O2, X3Σ −g) system yielding tin monoxide (SnO, X1Σ+) along with ground state atomic oxygen O(3P). The reaction can be initiated on the triplet and singlet surfaces via addition of tin to the oxygen atom leading to linear, bent, and/or triangular reaction intermediates. On both the triplet and singlet surfaces, formation of the tin dioxide structure is required prior to unimolecular decomposition to SnO(X1Σ+) and O(3P). Intersystem crossing (ISC) plays a critical role in the reaction mechanism and extensively interosculates singlet and triplet surfaces. The studied reaction follows a mechanism parallel to that for the gas phase reaction of germanium and silicon with molecular oxygen, however, the presence of the tin atom enhances and expands ISC via the "heavy atom effect". [ABSTRACT FROM AUTHOR]

© 2018, Allerton Press, Inc. The temperature and pressure-dependent rate constants for the process C10H7Br ↔ C10H7+Br were evaluated using the variable reaction coordinate transition state theory VRC-TST. The calculated rate constants and computational fluid dynamics (CFD) calculations were employed to estimate the pyrolysis efficiency of 2-bromonaphthalene in the resistively-heated SiC high-temperature “chemical reactor” at the temperature of about 1500 K. The observed 40% pyrolysis efficiency is reproduced by CFD calculations if the value of the calculated rate constant for the C10H7Br pyrolysis is increased by a factor of 2.

Objective. Flow metering and the evaluation of cryogenic product losses at production and consumption facilities involve determining the mass of the vapor-liquid medium in the tank equipment. Methods. The calculation of the mass of the cryogenic vapor-liquid medium is associated with the determination of the density of the vapor and liquid phases. The densities of media, in turn, depend on their component composition, pressure, and temperature, which, in general, cannot be determined reliably without direct measurements. However, for the estimation of mass in tanks, the state of the medium in which is accepted as equilibrium, the problem can be significantly simplified, and the missing information recovered based on indirect methods. This type of system includes cryogenic onboard fuel systems and, in particular, cryogenic fuel tanks, since the movement of the vehicle leads to mixing of the stored product, and an assumption can be made about the equilibrium of the vapor-liquid medium. Similarly, the methodology can be extended to transport tanks and multimodal reservoirs. Results. A review and comparison of the applied methods for calculating the density of the vapor-liquid medium and equilibrium compositions for hydrocarbon liquefied natural gas type mixtures in the cryogenic temperature range are presented. The existing methods for calculating the density and phase composition of cryogenic multicomponent media are complex in practical engineering and cannot be recommended for estimating the consumption of liquefied natural gas in the production tasks of fuel flow metering and quantity control. An easy-to-use simplified calculation device for determining the state of a vapor-liquid medium in cryogenic tanks based on approximation dependencies is proposed. Conclusion. The simplified method is approximate in nature but is based on strict physical dependencies, and therefore does not lead to a significant increase in the error when varying the initial conditions. The liquefied natural gas composition, which can be obtained from the product data sheet, and the pressure of the vapor-liquid medium are transmitted to the methodology as initial data.

The relevance of the study arises from the high technogenic impact on the environment of industrial zones, whose development associates with the production, storage, transportation, processing and consumption of oil and its products. Leaks, accidents, losses of products lead to the invasion of oil products into the environment that may results in serious environmental problems. Oil pollution is global in nature poisoning the biosphere and changing life conditions. The impact on the hydrosphere is one of the most significant, and is considered in this article on example of groundwater in industrial zones.

This paper discusses the potential of using infrared remote sensing data to determine geocryological conditions in the northern part of the Yenisei Ridge in Russia. Landsat-8 thermal infrared images and land surface data were used for our analysis. The obtained thermal characteristics were compared with vegetation indices calculated for the period of active vegetation growth along several surface transects. Surface observations included geobotanical descriptions, phytomass estimations, measurements of thickness of the seasonally thawed layer, and visual identification of different effects of permafrost on the components of the taiga landscape. The obtained surface temperatures differed depending of forest type due to their bio-productivity characteristics on sporadic permafrost as the most important factor of forest growth conditions within the southern part of the cryolithozone. The differences in the thermal characteristics are due to varying degree of permafrost influence on boreal vegetation growth. The surface temperature was used as indicator to quantify the relationship between the latent heat and the sensible heat fluxes for the corresponding landscape. The areas with higher surface temperatures were usually characterized by higher sensible heat flux due to lower evapotranspiration of the plant canopy. The forest types with the highest evapotranspiration had usually the lowest surface temperatures. Such forest types are also the most fire-resistant systems, and have the highest water-discharge potential. This is characteristic of the forests under the lowest impact of permafrost (thawed soils or the presence of the permafrost layer at lower depths). Such types of forests have higher ecosystem service potential (e.g., fire-resistance and stock formation).

A random narrow-linewidth lasing at a wavelength of 976 nm was obtained in an ytterbium-doped germanophosphosilicate fiber with an array of weakly reflecting fiber Bragg gratings (FBGs). A random laser cavity was formed by implementing the standard phase mask method of FBG inscription directly during the fiber drawing process. The UV radiation pulses of a KrF excimer laser (248 nm wavelength) synchronized with the fiber drawing speed were used to fabricate the in-fiber array of hundreds of similar FBGs. The developed laser’s slope efficiency in the backward-pumping scheme was measured as high as 33%. The stable continuous-wave operation mode of the laser was detected. The magnitude of the laser power fluctuations depends linearly on the cavity length. The random laser cavity modified with a single highlyreflected (90%) FBG demonstrates significantly better power stability and higher slope efficiency than the same one without an FBG.

Fiber single-frequency lasers are currently being actively developed, primarily due to the growing number of applications that require compact and reliable narrow-band sources. However, the most developed single-frequency fiber lasers based on phosphate fibers have the disadvantages of low mechanical strength of both the phosphate fibers themselves and their splices. In this paper we demonstrate a single-frequency laser based on a new composite Yb3+-doped active fiber. The core of this fiber is made of phosphate glass with a high concentration of ytterbium ions and its cladding is made of standard silica glass. This structure ensures a higher splicing strength of the fiber compared to the phosphate fibers and provides high resistance to atmospheric moisture. Despite the multimode structure of this fiber, we achieved stable single-frequency lasing with an average power of 10 mW and a spectral contrast of more than 60 dB in the scheme with a short (1.1 cm) cavity formed by two fiber Bragg gratings. We believe that further optimization of this fiber will make it possible to create powerful and reliable single-frequency lasers in the one-micron wavelength range.

The amplification of a weak narrow-spectrum pulsed signal at a wavelength of 2.27 µm in Tm3+-doped tellurite fiber was demonstrated. The double-clad Tm3+-doped TeO2–ZnO–La2O3–Na2O glass fiber was used as an amplifier active medium. The pulsed seed signal was selected from the supercontinuum by the high reflective fiber Bragg grating. The experimental setup allowed us to obtain pure amplification data over 2.2 µm without amplified spontaneous emission and nonlinear effects contribution. The gain coefficient of Tm3+-doped tellurite fiber was estimated as 0.11 m−1.

The reaction of the 1-propynyl radical (CH3CC; X2A1) with propylene (CH3CHCH2; X1A′) was studied in a crossed molecular beam machine at a collision energy of 37 ± 1 kJ mol−1. Experimental data combined with high-level electronic structure (CCSD(T)-F12/cc-pVTZ-F12//ωB97X-D/6-311G(d,p)) and RRKM calculations reveal the reaction mechanism. The overall barrierless and exoergic reaction involves indirect reaction dynamics and commences preferentially with addition of 1-propynyl with its radical centre to the carbon–carbon double bond at the terminal carbon atom of propylene. This work focuses on molecular mass growth process (hydrogen loss channels) although theory suggests methyl loss as a prevalent channel. In these processes, the C6H9 collision complexes either emit atomic hydrogen or undergo isomerisation followed by atomic hydrogen loss to preferentially yield the cis/trans isomers of 1,3-dimethylvinylacetylene (2-hexen-4-yne) as the primary product. Analysis of reaction dynamics of 1-propynyl and ethynyl radicals with propylene along with their fractional abundance in deep space suggests formation of methyl- and dimethyl derivatives of vinylacetylene in cold molecular clouds. Once formed they may engage in fundamental molecular mass growth processes via the barrierless Hydrogen Abstraction Vinylacetylene Addition mechanism that leads to the formation of methyl- and dimethylnaphthalenes thus providing a versatile route to methyl-substituted PAHs in interstellar medium. [ABSTRACT FROM AUTHOR]

A statistical evaluation of the control unit computer model for multi-agent robotic systems is carried out. An algorithm is considered that realizes the achievement of a single goal by robots-agents – to cross the intersection at the maximum speed. Let such algorithm be called an "algorithm for conflict solutions". The paper presents the study of the dependence of the vehicle appearance probability effect from each intersection side on the maximum speed of the intersection crossing. The efficiency of the applied algorithm is evaluated at the intersections of various types, for example: four-way intersection, T-junction, Y-shaped intersection. The efficiency estimation was performed by a full factorial experiment on the study of the "algorithm for conflict solutions" operation by the unmanned vehicle control unit. The basic idea of a full factorial experiment is that the researched object is considered as a "black box". Thus, the effect of input parameters (factors) on the response function is studied. The main benefit of full factorial experiment application is the construction of an experiment planning matrix that contains all possible combinations of factors. This approach gave the possibility to identify those combinations of factors that have the greatest and the least effect on the response function. The received results testify to the possibility of the algorithm for conflict solutions operation for intersection of various types of roads. The algorithm shortcomings were revealed. In future it is expected to use the obtained results to assess the information security of the multi-agent robotic system with decentralized and centralized control.

Exploiting the crossed molecular beam technique, we studied the reaction of the 1-propynyl radical (CH3CC; X2A1) with 2-methylpropene (isobutylene; (CH3)2CCH2; X1A1) at a collision energy of 38 ± 3 kJ mol−1. The experimental results along with ab initio and statistical calculations revealed that the reaction has no entrance barrier and proceeds via indirect scattering dynamics involving C7H11 intermediates with lifetimes longer than their rotation period(s). The reaction is initiated by the addition of the 1-propynyl radical with its radical center to the π-electron density at the C1 and/or C2 position in 2-methylpropene. Further, the C7H11 intermediate formed from the C1 addition either emits atomic hydrogen or undergoes isomerization via [1,2-H] shift from the CH3 or CH2 group prior to atomic hydrogen loss preferentially leading to 1,2,4-trimethylvinylacetylene (2-methylhex-2-en-4-yne) as the dominant product. The molecular structures of the collisional complexes promote hydrogen atom loss channels. RRKM results show that hydrogen elimination channels dominate in this reaction, with a branching ratio exceeding 70%. Since the reaction of the 1-propynyl radical with 2-methylpropene has no entrance barrier, is exoergic, and all transition states involved are located below the energy of the separated reactants, bimolecular collisions are feasible to form trimethylsubstituted 1,3-enyne (p1) via a single collision event even at temperatures as low as 10 K prevailing in cold molecular clouds such as G+0.693. The formation of trimethylsubstituted vinylacetylene could serve as the starting point of fundamental molecular mass growth processes leading to di- and trimethylsubstituted naphthalenes via the HAVA mechanism. [ABSTRACT FROM AUTHOR]

The fundamental reaction pathways to the simplest dialkylsubstituted aromatics—xylenes (C6H4(CH3)2)—in high‐temperature combustion flames and in low‐temperature extraterrestrial environments are still unknown, but critical to understand the chemistry and molecular mass growth processes in these extreme environments. Exploiting crossed molecular beam experiments augmented by state‐of‐the‐art electronic structure and statistical calculations, this study uncovers a previously elusive, facile gas‐phase synthesis of xylenes through an isomer‐selective reaction of 1‐propynyl (methylethynyl, CH3CC) with 2‐methyl‐1,3‐butadiene (isoprene, C5H8). The reaction dynamics are driven by a barrierless addition of the radical to the diene moiety of 2‐methyl‐1,3‐butadiene followed by extensive isomerization (hydrogen shifts, cyclization) prior to unimolecular decomposition accompanied by aromatization via atomic hydrogen loss. This overall exoergic reaction affords a preparation of xylenes not only in high‐temperature environments such as in combustion flames and around circumstellar envelopes of carbon‐rich Asymptotic Giant Branch (AGB) stars, but also in low‐temperature cold molecular clouds (10 K) and in hydrocarbon‐rich atmospheres of planets and their moons such as Triton and Titan. Our study established a hitherto unknown gas‐phase route to xylenes and potentially more complex, disubstituted benzenes via a single collision event highlighting the significance of an alkyl‐substituted ethynyl‐mediated preparation of aromatic molecules in our Universe. [ABSTRACT FROM AUTHOR]

Sharp differences in natural environment and resources and demographic and economic characteristics in Russia place special importance on analysis of regional models of transition to “green economy.” Regional model of transition to“green economy” for the Khanty-Mansi Autonomous Okrug-Ugra is discussed. This region is situated in Siberia and is leading in hydrocarbons extraction (57% of the country’s total). The existing nature management pattern is closely connected with poor modern ecological situation. System analysis of preconditions for the transition of the Khanty-Mansi Autonomous Okrug-Ugra to green economy is presented. It includes description of limiting and promoting natural and social-economic factors and consideration of the ecological situation. Economic, institutional, and nature management tools for regional transition to “green economy” and sustainable development are demonstrated. These tools reflect regional pattern of “green economy” movement, though common mechanisms play the leading role (e.g., energy efficiency, climatically neutral production, environmental accounting, etc.). Regional pattern includes specific measures for forests preservation, ethnic-culture tourism development, organic agriculture based on reindeer meet, wild berries and mushrooms production, etc.

This article discloses the analysis of «feeding landscapes» and their natural ecological resources, which are the basis of life support systems of indigenous populations. We consider all following risks and changes of their traditional lifestyle. By the example of one of ethnic groups we demonstrate coping strategies and adaptations to climatic and environmental changes with due consideration of ethno-cultural specifics.

This article discloses the analysis of «feeding landscapes» and their natural ecological resources, which are the basis of life support systems of indigenous populations. We consider all following risks and changes of their traditional lifestyle. By the example of one of ethnic groups we demonstrate coping strategies and adaptations to climatic and environmental changes with due consideration of ethno-cultural specifics.

This paper presents the method of remote detection and mapping of permafrost landscapes. These natural complexes visually are significant not only on the terrain, but easily distinguished by thermal characteristics on surface temperature maps, obtained by processing data from Landsat TM and Terra ASTER. The possibility of using thermal images data for such aim relies on the work of M.I. Budyko about the structure of earth’s surface heat balance. This method is also confirmed by field studies.