Development and design of low power mobile and inexpensive solar stations are important for farmers, individuals, geologists and trotters. The most important aspect is ensuring reliability of units in times of transportation, convenience and operational ease as well as minimum dimensions, low price. All the above will ensure large-scale implementation of solar stations in various applications and utilizations.

In the present paper, first, we study the event horizon properties of charged black holes (BHs) in Einstein Maxwell-scalar (EMS) gravity. Then, we investigate the circular motion of test particles’ around the BH in the EMS gravity. We also analyze the effects of the EMS parameters on the position of innermost circular orbits (ISCOs), energy, and angular momentum of the test particles corresponding to circular orbits. We provide detailed studies of the efficiency of energy release from EMS BHs based on the Hartle–Thorne model and fundamental frequencies of oscillations of particles along their circular stable orbits. Moreover, we have explored possible values of upper and lower frequencies of twin-peak quasiperiodic oscillations (QPOs) around the BHs. Finally, we obtain relationships between the BH charge and the EMS parameters using observational data from the QPOs detected in the microquasars: GRS 1905+105, GRO J 1655-40, H 1745+322, and XTE 1550-564.

The article considers the ways to solve optimization problems of drill bits on a deterministic basis through studying and using the “Regularity of energy consumption of dynamic systems from resistance to motion forces”, which directly indicates the causes of bit balling formation, the reasons for the insufficient stability of the bearing assemblies of the cones, the causes of instability of the drill bits at the bottom of the well. Theoretical grounded search was done to use certain methods for designing drill bits of cutting-abrasive type, working in the rotational steam mode, which determine uniform wear of armaments for all crowns of working matrices and uniform destruction of the rock through all of the annular bottom hole.

This paper presents a new method of soft start of high-voltage and high-power asynchronous electric drives of auxiliary units in mining enterprises, pumping sta This paper presents a new method of soft start of high-voltage and high-power asynchronous electric drives of auxiliary units in mining enterprises, pumping sta

The article describes the dynamics of drill bits, drilling modes, distribution of resistance forces when drilling with bits. The theory of drilling a well of arbitrary shape, possible shapes of contacting figures at the bottom hole and the type of drill bit operating in the rotation pair mode are considered. This type of bit has the properties of a double center of rotation, which results in attrition drilling. At the same time, during drilling, the load on the bit will be located the same throughout the working part, it is also theoretically shown that the specific volumetric and contact work of the cutting parts will be the same, which leads to the same wear of the bit. It also discusses the issues of improving the flushing and blowing of wells when drilling with rotary steam bits.