The production of metal nanopowders with specified sizes requires an analysis of the relationship between the physical conditions in industrial installations and the geometric properties of nanoparticles. Predictive mathematical modeling is one of the possibilities of investigating this relationship. The use of thermodynamic nucleation models does not allow one to achieve quantitative agreement with experiment results, so the data can differ by a few orders of magnitude. The kinetic Monte Carlo methods popular in recent decades make it possible to approach the scale of a real experiment; however, they consider an initial state of a medium as ideal crystalline nuclei formed in advance and evenly distributed in space, on the surface of which adsorption and desorption processes take place, and monomers diffuse to their surface in the medium. The rates of these processes are determined by coefficients, the values of which can be chosen to best describe experimental data or calculated using MD simulation. These methods do not consider the stage of nucleation and a detailed description of nucleation; therefore, it is impossible to take into account, e.g., the appearance of stable isomeric forms, "magic" clusters, and so on. In this work, we perform a multiscale simulation of the nucleation of copper nanoparticles in a gas-phase condensation chamber. The data used for a mathematical description of the atomic level of nucleation are obtained by analyzing the results of molecular dynamics calculations of copper vapor condensation at various degrees of supersaturation. The microdescription results are used in a macroscopic model, which includes a system of equations of motion, heat conduction, and diffusion. The analysis includes a description of nucleation, unimolecular growth, and coagulation. The concentrations of clusters of various sizes are taken into account on a logarithmic scale. In areas with a temperature close to the boiling point of copper, cluster grow is found to occur mainly via the attachment of monomers; in low-temperature areas, coagulation is the predominant growth mechanism.

Despite the growing popularity of supercapacitors (supercondensers), the common model of discharge and the unified method of describing their characteristics are not available as of yet. This is explained by the complexity of the physical and chemical processes occurring there. This work provides an analysis of the charge/discharge curves for a laboratory-manufactured and an industrial supercapacitor. It has been shown that a two-step discharge mechanism is typical for the supercapacitors under study, unlike for usual capacitors, and time constants differ by approximately one order of magnitude. Fast discharge is determined by the internal parameters of a supercapacitor, and the time constant of this process does not depend on the external resistance. For a slow process, the time constant is in linear dependence with the external resistance, that is why this process is analogous to the discharge of a usual capacitor. Using the parameters of the slow process, it is possible to determine the effective internal resistance of the supercapacitor and its capacity. The ratio of speeds of the fast and slow discharge in case of a laboratory-manufactured and an industrial supercapacitor is approximately equal, what is indicative of the similarity of the processes occurring there. A significant difference between supercapacitors is observed in the ratio of voltage amplitudes corresponding to the fast and slow processes. For an industrial supercapacitor, the contribution of the voltage of the slow process (which depends on the external circuit parameters) is considerably higher, what proves its higher efficiency during operation in electric circuits.

As a result of the Post-Cold War development, the international relations have shifted from bipolarism to a multipolarism. Once relevant Western-born IR theories lack explanatory power. Current IR witness the growing role of the non-Western states both in regional and international domains. Consequently, there is a growing need for appropriate IR theories that could explain the changing world structure, describe the role of new powers in international politics and define future development. Thus, it is essential to study non-Western research that focuses on conceptualization of ongoing processes from its perspective. The authors analyze the IR theories developed by South Korean scholars. The purpose of this article is to analyze South Korean interpretations of the middlepowermanship that considers the Republic of Korea’s unique regional and global context. South Korean scholars agree on a particular geostrategic location of the state. The geopolitical location, absence of natural resources and limited military power hinder South Korea’s ability to use hard power in regional and international politics. However, South Korea’s economic development and creative approach in foreign policy translate into middle power diplomacy, which includes niche diplomacy, moderating role in relations between greater powers, regional cooperation promotion, and development of the international legal system. The authors conclude that South Korean version of middle power theory is continuously being (re) interpreted and adapted to the country’s foreign policy. South Korea is to be a a bridge between the great powers in the region.

In this work, we set out to develop a model of gas-phase nucleation in a mixture of copper and argon atoms, which can be further used for analysing macro-systems. Processes occurring at the atomic level are described using coefficients obtained by statistical analysis of molecular dynamic (MD) data on interactions of metal clusters with metal and argon atoms. The MD simulation results are compared with those obtained using the proposed macroscopic model. It is found that the coefficients obtained by averaging the interaction data suitably represent the integral value of the heat of condensation, although result in the smoothing of the energy distribution functions of the clusters. Analysis of the evolution of the number of clusters has shown that the values of their increase rate were lower than those obtained by MD simulation. The conclusion is made, that in order to improve the precision of the developed gas-phase condensation model, it should be supplemented by cluster coagulation.

Statistical analysis of the results of molecular dynamics (MD) calculation of gas-phase “self-assembling” of nanoclusters during metal vapor condensation revealed the laws of energy transfer between metallic clusters and inert gas atoms. A model is proposed to determine the parameters of heat exchange between clusters and the environment at the initial stage of condensation. This model is based on averaged MD data on the interaction between small clusters and argon atoms. The parameters that can be used to transfer information from MD to a macroscopic condensation model are numerically determined. The results obtained can be used to describe nucleation to predict a nanoparticle size distribution in the production of metallic powders.

The results of the molecular-dynamic calculations of gas-phase nanocluster “self-assembly” during metal vapor condensation have been statistically analyzed parting terms of a computational scheme suitable for describing condensation. The laws of collisions and the growth of small copper clusters are revealed. The parameters that describe the interaction between clusters and metal atoms and are used to transfer information to a macroscopic nucleation model are determined. The results can be used for describing nucleation for predicting a nanoparticle size distribution in the production of metal nanopowders.

A molecular dynamics study was carried out on the dependence of the radii of small metal clusters that form in the process of gas-phase copper condensation on the number of atoms in them. The radii are calculated with the molecular-kinetic theory formulas from molecular-dynamic simulating data on the number of collisions between clusters. It was found that the dependence of the radii on the number of particles has a form close to the classical n1/3. However, the average cluster radii are about 40% larger than the case in which the cluster is considered a drop of a bulk fluid.

A computing scheme for a mesoscopic description of a nucleation process has been built using a statistical analysis of the results of molecular dynamics simulation of a supersaturated metallic vapor. The parameters that enter into equations for cluster growth rate and heat release during condensation are found by a direct statistical computation in a molecular dynamics method. The rates of cluster formation calculated by a molecular dynamics method agree well with the numerical model developed in this work.

A statistical analysis of the results of molecular-dynamic calculations of metal (Cu or Ti) vapor condensation in an inert gas (Ar) medium has been performed. Condensation proceeds with the formation of small particles consisting of metal atoms—clusters. The internal energy of the metal cluster—the sum of the kinetic energy of the atoms in the center of mass system and potential energy—is chosen as the key characteristic describing its state. It is shown that the internal energy value gives the possibility for the prediction of the duration of the cluster existence, from birth to decay, i.e., it describes the ability of the cluster to grow. The temporal evolution of the distribution function of the clusters over the internal energy values is presented.

We discuss the problem of dimer formation during the homogeneous nucleation of atomic metal vapor in an inert gas environment. We simulated nucleation with molecular dynamics and carried out the statistical analysis of double- and triple-atomic collisions as the two ways of long-lived diatomic complex formation. Close pair of atoms with lifetime greater than the mean time interval between atom–atom collisions is called a long-lived diatomic complex. We found that double- and triple-atomic collisions gave approximately the same probabilities of long-lived diatomic complex formation, but internal energy of the resulted state was essentially lower in the second case. Some diatomic complexes formed in three-particle collisions are stable enough to be a critical nucleus.

Statistical analysis of the results of molecular-dynamic modeling for nucleation of metal (Cu) vapors in inert gas atmosphere (Ar) is carried out. Features of the initial stage of nucleation are considered for estimation of the probability of the growth of small atomic clusters within a supersaturated nonequilibrium medium and the efficiency of heat removal from them during collisions with inert gas atoms and other metal atoms.

The structure of overheated metal clusters appeared in condensation process was studied by computer simulation techniques. It was found that clusters with size larger than several tens of atoms have three layers: core part, intermediate dense packing layer and a gas-like shell with low density. The change of the size and structure of these layers with the variation of internal energy and the size of cluster is discussed.