Methods: The construction of optimal control for angular momentum change is based on the quaternion method and L.S. Pontryagin maximum principle. An analytical solution to the problem was obtained on the base of a differential equation relating the orientation quaternion and angular momentum of a spacecraft.

Results: Key properties of the optimal solution are formulated in analytical form; the features of optimal motion are studied in detail. The control law is formulated in the form of explicit dependence between control and phase variables. In a case when the controlling torque is limited by the given restriction (at the beginning and end of a turn), analytical formulas have been written for the duration of braking and acceleration. Main relations which determine optimal values of parameters of the algorithm for control of angular momentum are given. Examples and results of mathematical modeling of spacecraft motion formed by optimal control were given. This data in addition to the theoretical descriptions illustrates the process of reorientation in evident form and demonstrates the practical feasibility of a designed method for control of angular momentum during spatial turn.

Conclusion: The designed optimal algorithm of control of spacecraft motion improves the efficiency of spacecraft attitude system, and originates more economical performance of spacecraft during flight on orbit.

]]> Method: This study examines NH_{3} and CO_{2} in thermally processed H_{2}O-rich ices in the laboratory via mid-infrared absorption spectroscopy. In particular, the presence of CO_{2} in NH_{3}-ice mixtures thermally annealed at 150 K for more than four hours in systematic experiments suggested that ammonium carbamate could potentially trap volatiles within the ice matrix.

Result: Additional studies with acetonitrile (C_{2}H_{3}N) in ice mixtures containing H_{2}O, CO_{2}, and NH_{3} were also performed. Absorption peak position changes were recorded when the temperature was slowly increased (≤ 5K/min) and also annealed at temperatures up to 150 K.

Conclusion: These studies will hopefully be useful in interpreting pre-biotic chemistry in the Solar System.

]]> Method: Presently, modifying the flake size of bulk Ti_{3}C_{2}T_{x} typically involves complex and costly processes, like ultrasonic treatment and isolation. Leveraging the specific preparation principle of MXenes, which involves etching the A layers in precursor MAX phases, a topdown strategy for producing Ti_{3}C_{2}T_{x} flakes of desired sizes, has been proposed in this work. In this approach, precursor Ti3AlC2 particles undergo ball-milling to adjust their size.

Result: Through this innovative strategy, dispersions of Ti_{3}C_{2}T_{x} flakes with varying average lateral sizes are generated, enabling an investigation into the impact of lateral size on the electrochemical properties of Ti_{3}C_{2}T_{x} flakes. By controlling the ball milling time for Ti_{3}AlC_{2} powders, the resulting average sizes of Ti_{3}C_{2}T_{x} (0, 2, 4) are 6.34 μm, 2.16 μm, and 0.96 μm, respectively. Particularly, the Ti_{3}C_{2}T_{x} (2) electrode, composed of 2.16 μm sheets, demonstrates remarkable performance metrics. It exhibits a high areal capacitance of 845.0 mF/cm^{2} at a scan rate of 5 mV/s, along with a gravimetric capacitance of 244.0 F/g at a current density of 1 A/g.

Conclusion: This study presents a facile method to enable mass production of Ti_{3}C_{2}T_{x} with sheets of varying sizes, addressing both small and large dimensions.

Method: The possibility of using high-power microwave systems to combat harmful animal pests in agriculture and forestry is discussed. The proposed method is compared favorably with respect to the environment.

Results: The obtained results of the study demonstrated the possibility of using modern sources of high-power microwave radiation to solve the problem of insect invasion.

Conclusion: It should be noted that the use of powerful microwaves is a promising means of controlling locusts and other pests. Mobile international forces equipped with modern microwave apparatus can solve the problem of combating locusts and other pests on a global scale without harming the environment. Microwave systems can also be used against other phytophagous pests of agriculture and forestry.

]]>Method: The model, based on two sputtering mechanisms, makes it possible to calculate the total sputtering coefficients of the target components, and it is easily transformed for the case of sputtering different types of targets. Model testing was conducted for the case of sputtering homogeneous tungsten carbide targets with ions of different energies.

Results: The results of the calculations are given in comparison with experimental data and the results of computer simulation. The comparison shows good agreement of the calculated values with the data of other authors. The proposed model was used to describe stationary (stoichiometric) sputtering of tungsten carbide targets. Using this model, the concentrations of components in the modified target layer were calculated, and the thickness of the modified layer was also estimated.

Conclusion: The method of calculating the concentration of target components in the modified layer and the thickness of this layer can be the basis of the technology of creating materials with given properties of the surface layer.

]]>Methods: The NiO NPs and conducting polymer Polyaniline were prepared by modified Sol-gel and chemical oxidative methods, respectively. Powder XRD, FTIR, TEM, and UV-visible methods were used for the structural evaluation. The computational (DFT) study was performed to support experimental results. The NiO/Polyaniline (PANI) nanocomposites (NCs) were explored as corrosion inhibitors, electrical conductors, and photocatalytic agents.

Results: The NiO/Polyaniline NCs showed 91.52% corrosion inhibition efficiency at 1000 ppm concentration. The photocatalytic activity was investigated against methylene blue dye under ultraviolet light. The NiO/Polyaniline NCs decompose 90% of organic dye. The NCs exhibit good conducting, corrosion inhibition, and photocatalytic activity.

Conclusion: The metal oxide (NiO NPs) and PANI-based NCs can be used as corrosion inhibitors, conducting material, and for the degradation of organic compounds (dyes) in impure water.

]]>Method: The experimental setup implementing the free mass method is described. Notably, the proposed scheme does not require any adjustment and is assembled from standard devices. By changing the design of the sample only, both shear and compression-tension strains can be measured. The combination of these methods allows measuring the complex Poisson’s ratio, in addition to modulus of elasticity and loss factor.

Results: One-dimensional (1D) and two-dimensional (2D) models of specimen deformation are considered. For the 1D deformation model, approximate formulas for calculating the modulus of elasticity and the loss factor are substantiated and the limits of validity these formulas are outlined. Improving the accuracy of measurements is also considered. To do this, it is necessary to fully describe the boundary conditions on the deformable sample. The developed 2D model of sample deformation made it possible to calculate the elastic modulus form factors for various samples with axial symmetry.

Conclusion: The method may become a Standard for measuring viscoelastic properties of materials (complex elastic and shear modulus, as well as complex Poisson's ratio).

]]> Methods: Tree rings are a reliable basis for obtaining a radiocarbon time scale (IntCal13). However, determining the concentration of ^{14}C in tree rings is a difficult and controversial task. The time scale derived from the ^{10}Be production rate simulation (GICC05) is less reliable. Nevertheless, there is a way to combine the accuracy of the radiocarbon time scale with the reliability of estimates of the ^{10}Be production rate. This method is the synchronization of the radiocarbon and beryllium-10 series.

We have selected the most relevant methods for calculating the solar modulation parameter φ for the Holocene. When calculating φ, ^{10}Be data synchronized with ^{14}C data were used. The latest data on the earth's dipole moment were considered. Empirical Mode Decomposition (EMD) was used in the analysis of φ.

Results: It has been shown that the first two decomposition modes are oscillating components with periods of 710 and 208 years, the amplitudes of which increase with time, reaching a maximum of 2500 BP. From contemplation, it follows that the 710-year oscillations are apparently caused by fluctuations in the tilt of the earth's dipole. After excluding the EMD component associated with the 710-year cyclicity, a corrected series was obtained for the solar modulation parameter, free from the influence of changes in the tilt of the magnetic dipole.

Conclusion: The rate of formation of cosmogenic radionuclides depends on the intensity of penetration of Galactic Cosmic Rays (GCRs) into the earth's atmosphere. Before reaching earth, GCRs must cross the heliosphere, where they are exposed to solar modulation. Adequate consideration of solar modulation parameters is important for the correct interpretation of the rate of production of cosmogenic isotopes and solar activity.

]]>Methods: Modification of the gyrotron design promotes the widespread use of these devices for DNP/NMR spectroscopy.

Results: Promising non-canonical concepts are presented, the features of which compare favorably with the classical gyrotron scheme.

Conclusion: The gyrotron concepts we considered allow us to master the terahertz range and develop a unique gyrotron installation for each scientific group, considering the specifics of their scientific research.

]]>Methods: Two important assumptions are that there exists a weak fermion of rest energy 585 GeV and strong coupling constant is the squared ratio of electromagnetic charge and nuclear charge. The aim of this paper is associated with understanding the mystery of the quantum of magnetic flux, Planck’s quantum radiation constant and Reduced Planck’s constant. Proceeding further, quark charges, strong coupling constant, nuclear stability, nuclear binding energy, medium and heavy atomic X-ray levels and celestial magnetic moments can be understood in a unified approach. It may also be noted that, by considering the integral nature of elementary particle masses, it seems possible to understand the discreteness of angular momentum.

Results: Considering our proposed e_{n}=2.95e=3e as a characteristic nuclear charge, it seems possible to understand the integral nature of quarks electromagnetic charge. With this idea, neutron, proton and pion decay can be understood very easily.

Conclusion: In all the cases, the up quark of charge (±2e) seems to play a crucial role in the internal transformation of the down quark of charge (±e) and external observable elementary basic elementary particles. It needs further study at the fundamental level. Proceeding further, quantum of magnetic flux, Planck’s radiation constant and Reduced Planck’s constant can be understood with our 4G model of final unification.

]]>Methods: We analyzed in detail the three fundamental laws of quantum mechanics, explicitly describing experimental data: 1) Planck’s law of the blackbody electromagnetic radiation of a system of electrically charged harmonic oscillators, 2) Einstein’s law of the photon energy proportionality with the photon frequency, and 3) de Broglie’s law of the quantum particle as an oscillator in space.

Results: We reobtained the two dynamical equations, in the conjugate spaces of the coordinates and momentum, as functions of the Lagrangian system, unlike the Schrödinger equation, depending on the Hamiltonian.

Conclusion: According to the fundamental laws of quantum mechanics, a quantum particle is a continuous distribution of matter with an intrinsic mass, unlike the conventional quantum mechanics for the state occupation probabilities of punctual entities moving with the light velocity and getting an apparent mass only by collisions with some bosons pervading the whole universe. According to these laws, we obtained a quantum theory in agreement with common sense, classical logic, and general relativity.

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