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We present the results of calculating the vibrational and rotational terms of the X²Π and B²Σ⁺ electronic states of the phosphorus oxide (PO) molecule. The absorption spectrum corresponding to the electronic transition B²Σ⁺ (v′ = 0) - X²Π (v″ = 0) has been calculated. The efficiency of laser excitation of PO molecules is estimated as a function of the spectral parameters of the radiation. It has been established that the excitation efficiency of the B²Σ⁺ (v′ = 0) - X²Π (v″ = 0) electronic transition of the PO molecule is approximately an order of magnitude lower than that of the A²Σ⁺ (v′ = 0) - X²Π (v″ = 0) transition. The result is of practical importance from the point of view of choosing the optimal scheme for laser excitation of the fluorescence of PO-fragments in the implementation of the method of remote detection of organophosphates.

The results of mathematical simulation of biogeochemical processes during the autumn cooling of the lake are presented. The influence of wind on the distribution of phyto- and zooplankton, nitrate, ammonium, and phosphate nutrients is studied during the existence of the autumnal thermal bar in Barguzin Bay of Lake Baikal. Numerical simulations show the autumnal thermal bar in combination with the effect of western winds, which act opposite to the thermal front direction, to significantly slow down the transport of plankton biomass toward the central part of the bay.

He methods and results of numerical prediction of the maximum thickness of ice deposits are described. The success of ice deposition forecasts is estimated from calculations based on the WRF-ARW model output for different Russian regions.

An algorithm is developed and, on its basis, a software product is created to control the photon counter and to save the data from recording system of the lidar’s receiving channel at wavelengths of 299/341 nm in atmospheric sensing with a spatial resolution from 1.5 to 150 m. The main software options are: device connection check; receiving lidar sensing data; data digitization; graphical displaying; data filing; conversion of .dat into .txt file format. The software product is experimentally tested along with the mobile ozone lidar receiver unit, incorporated into the software part of the measurement complex of the Siberian Lidar Station. The receiver unit of the mobile ozone lidar comprises a photon counter PHCOUNT_4Е and Hamamatsu photoelectronic multipliers H12386-210. We present the atmospheric lidar sensing data and an ozone concentration profile retrieved in 2022.

The effect of collisional line broadening on the accuracy of tropospheric (0-11 km) temperature measurements with pure rotational Raman (PPR) lidars at their absolute calibration by spectroscopic parameters was estimated via numerical simulation. The simulation was performed for five sets of spectral filters (SF) with different passbands in a lidar spectral selection unit and an outgoing laser signal wavelength of 355 nm. It is shown that the unavoidable absolute calibration error can reach values from 0.14 to 0.44 K (depending on the SF set) when ignoring the N₂ and O₂ PRR line broadening. The line broadening can be neglected if only one PRR line is extracted in each of the two lidar channels (for example, using a Fabry-Perot interferometer).

The article describes the lab-scale testing of dynamic instability in a block placed on a rough slope surface and subjected to small-amplitude vibrations. It is shown that the macroscopic sliding evolution is well-presented using equations of creep with the properly selected constants. According to the testing data, the necessary condition of the dynamic failure is the critical displacement along the slope and the certain creep rate. The critical displacement appears to exceed greatly the typical value when the sliding surface transits to the residual shear resistance. It is found that the landslide body instability develops at the late stage due to the phenomenon of reduction in friction at increasing sliding velocity.

The granular and other similar-type materials without cohesion are tested on various mode shearing machines. The complex loading machine with continuous rotation of principal strain axes is described. Loading represents a superposition of the planar and parallel Couette flows (simple shears) between parallel plates rotated at a certain angular rate. The stress and dilatancy data of quartz sand in deformation on the designed equipment are reported. It is found that stresses and dilatancy in cyclic deformation tend to stationary values. The stationary values of dilatancy increase with increasing shearing strain. The stationary deformation stresses change periodically, their average values weakly depend on the cyclic strains and their amplitude increases.

The article presents a real case of twin tunnels T4 of the East-West Highway (Algeria) for studying purpose of the effects therein on the soil-structure interaction and the excess pore water pressure on the same by use of a numerical analysis PLAXIS 3D. The results obtained from the Mohr-Coulomb model have been compared with those of Hardening Soil Model for drained and undrained condition. More to the point, it indicates that the soil under undrained condition can produce a significant modification in the normalized internal forces and the moment of lining for the stiff tunnels compared to flexible tunnels.

The authors describe numerical modeling of a growing fracture created between two parallel boreholes in an isotropic medium in the nonuniform stress field. The fracture paths are modeled at various deviations of the initial fracture from the axes of boreholes, spacing of the boreholes and the compressive stress field between them. Physical simulation of hydraulic fracturing is implemented using large-size samples.

A series of laboratory cutter indentation tests were conducted on mudstone samples to study the influence of thermo-mechanical coupling on rock fragmentation. The experimental results show that many micro cracks and pores are formed in the crushed zone of rock sample due to the frictional heat during cutting process. After that, the relationships between specific energy and mesoscopic surface of mudstone samples were analyzed. The results show that the thermo-mechanical coupling is conductive to rock fragmentation. Therefore, thermo-mechanical coupling action in the tunneling process greatly improves the rock breaking efficiency. This study is conducive to extend cutter life, reduce project cost and construction risk in TBM tunnel project.