Search

Resonant electron capture by aza and diaza derivatives of phenanthrene (7,8-benzoquinoline and 1,10-phenanthroline) and anthracene (acridine and phenazine) at incident free electron energies (Ee) in the range of 0–15 eV was studied. All compounds except 7,8-benzoquinoline form long-lived molecular ions (M−) at thermal electron energies (Ee ∼ 0 eV). Acridine and phenazine also form such ions at epithermal electron energies up to Ee = 1.5–2.5 eV. The lifetimes (τa) of M− with respect to electron autodetachment are proportional to the extent of aza-substitution and increase on going from molecules with bent geometry of the fused rings (azaphenanthrenes) to linear isomers (azaanthracenes). These regularities are due to an increase in the adiabatic electron affinities (EAa) of the molecules. The EAa values of the molecules under study were comprehensively assessed based on a comparative analysis of the measured τa values using the Rice–Ramsperger–Kassel–Marcus theory, the electronic structure analysis using the molecular orbital approach, as well as the density functional calculations of the total energy differences between the molecules and anions. The only fragmentation channel of M− ions from the compounds studied is abstraction of hydrogen atoms. When studying [M–H]− ions, electron autodetachment processes were observed, the τa values were measured, and the appearance energies were determined. A comparative analysis of the gas-phase acidity of the molecules and the EAa values of the [M–H]· radicals revealed their proportionality to the EAa values of the parent molecules. [ABSTRACT FROM AUTHOR]

Within the framework of this article, examples of solving specific problems related to the flow of fluid to a well in basin conditions and the flow of groundwater in limited layers, affecting environmental pollution, are considered. The purpose of the work is to study the use of complex potentials in the study of well performance in limited areas, to describe the performance of wells in systems of production and injection wells. The research hypothesis is that under conditions of natural migration and accepted limitations, streamlines and equipotentials can play the role of impermeable boundaries and boundaries of free liquid. To construct complex flow potentials for wells in typical reservoir patterns, conformal transformation methods were used. A method for determining the permissible flow rate of a well without contamination is considered. The authors have identified the conditions for the spread of pollution in the presence of their source, which are solved based on the use of complex potentials that describe the flow.

Today, the creation of new vehicles is impossible without computer modeling. Modern vehicles have numerous electronic systems that increase its traffic safety, comfort, and route planning management. Reliable operation of all systems is achieved by using an accurate dynamic model of the vehicle to assess safety and the possibility of movement along specified trajectories. Creating an accurate dynamic vehicle model requires correct initial parameters. When modeling the curvilinear movement of motor vehicles, such parameters as the coefficients of resistance to lateral sliding of tires and the angles of sliding of axles, which are mainly determined on test benches in laboratory conditions, are important to obtain the adequacy of the object under study. However, quite often it is impossible to obtain reliable information from tire manufacturers or testing laboratories, which ultimately affects the adequacy of modeling the parameters of vehicle movement. A method is proposed for determining the design parameters of tires using primary information sensors, which are sensors of angular and linear velocities, linear accelerations, rotation angles of controlled wheels and an on-board information processing device. The advantages of this method are that it allows real-time measurement of the angles of the axles and the coefficients of resistance to the lateral withdrawal of the axles when the vehicle is moving at an arbitrary speed along a trajectory of variable curvature. This method can be used to create an accurate dynamic model in the study of the controllability and stability of the vehicle, as well as an integral part of the vehicle dynamics control system.

The Chuvash Republic belongs to the territories with a high frequency of occurrence of emergency situations of moderate severity. This is due to the intensive economic development of the region. The probability and intensity of the manifestation of georisks is different for individual landscapes, therefore it needs a detailed study. The study includes the study of the probability of the development of slope, climatic, hydrological risks, and the risk of wildfires on the territory of the Chuvash Republic. The analysis showed that the slope type of geoecological risk is confined to the river valleys of the region and has maximum values in the north of the Chuvash Republic. A high risk of flooding and flooding exists in the valleys of major rivers of the region (Volga, Sura) and their tributaries of the first order. On other watercourses, the hydrological risk is not significant. Climate and weather risks are associated with hurricane winds and dry winds. The southeastern part of the region suffers the most from them. The risk of fires depends on the composition and age of the stand. The maximum risk values are typical for the Prisursky forest area (southern and southwestern parts of the region). Based on the data obtained, the classification of the districts of the Chuvash Republic by the size of the georisks was carried out. Four groups of districts were identified according to the probability of natural emergencies and the main factors of their occurrence were described.

The use of biogas in the internal combustion engine (ICE) requires the purification of harmful impurities that reduce the quality of operation of the ICE fuel system. A filter device for biogas purification is presented. The zeolite from the Khonguruu deposit of Suntar ulus of the Republic of Sakha (Yakutia) has been tested as a filter to separate impurities. The results of a multifactor experiment on the main factors of the biogas purification process are given: the size of the fractions, the filtering material, its mass, the ratio of the bulk material height to the filter diameter. The best results on biogas purification were obtained at the ratios of the height and diameter H/d=3.0:4.2. The optimum weighted average diameter of granules of the bulk filter material (zeolite) was selected – 0.004 m. and mass of filter media – 0.75-0.8 kg. At these values, the maximum level of biogas purification is observed, where the methane content is 93.3%.

This paper presents the reliability assessment results for electromechanical modules, including carbon fiber reinforced composite with thermoplastic matrix, aluminium alloy, and steel housing, through the analysis of competing risks, establishing an association among reliability indicators and non-stationary failure flow using the Weibull probability density function. It has been demonstrated that the estimated probabilities of reliability operations and failure are merely approximations and may deviate from the actual values. This analysis correlates with the estimation of mutual competing risks in the operation of planetary gearbox housing constructed from composite materials. It has been confirmed that the estimated probability of failures is asymptotically effective. A comparative analysis illustrates reliance on simulation methods for planetary gearbox housing made of carbon fiber reinforced composite with a thermoplastic matrix, aluminium alloy, and steel, focusing on parameters such as von Mises stress and deformation (deflection). It has been proven that the electromechanical module, including carbon fiber reinforced composite with thermoplastic matrix, aluminium alloy, and steel planetary gearbox housing is the most reliable, with the lowest heat transfer coefficient, but with the lowest strength. [ABSTRACT FROM AUTHOR]