Electrocaloric Response of the Dense Ferroelectric Nanocomposites

Using the Landau-Ginzburg-Devonshire approach and effective media models, we calculated the spontaneous polarization, dielectric, pyroelectric, and electrocaloric properties of BaTiO$_3$ core-shell nanoparticles. We predict that the synergy of size effects and Vegard stresses can significantly improve the electrocaloric cooling (2- 7 times) of the BaTiO$_3$ nanoparticles with diameters (10-100) nm stretched by (1-3)% in comparison with a bulk BaTiO$_3$. To compare with the proposed and other known models, we measured the capacitance-voltage and current-voltage characteristics of the dense nanocomposites consisting of (28 -35) vol.% of the BaTiO$_3$ nanoparticles incorporated in the poly-vinyl-butyral and ethyl-cellulose polymers covered by Ag electrodes. We determined experimentally the effective dielectric permittivity and losses of the dense composites at room temperature. According to our analysis, to reach the maximal electrocaloric response of the core-shell ferroelectric nanoparticles incorporated in different polymers, the dense composites should be prepared with the nanoparticles volume ratio of more than 25 % and fillers with low heat mass and conductance, such as Ag nanoparticles, which facilitate the heat transfer from the ferroelectric nanoparticles to the polymer matrix. In general, the core-shell ferroelectric nanoparticles spontaneously stressed by elastic defects, such as oxygen vacancies or any other elastic dipoles, which create a strong chemical pressure, are relevant fillers for electrocaloric nanocomposites suitable for advanced applications as nano-coolers.Comment: 38 pages, including 10 figures and 2 appendixe

Development of A Method for Assessing Forecast of Social Impact in Regional Communities

The development of the social aspect of the world community is closely related to the expansion of the range of digital services in cyberspace. A special place in which social networks occupy. The world's leading states are conducting information operations in this environment to achieve geopolitical goals. Such processes are reflected in real social and political life. This makes it possible to influence not only the social groups of society, but also to ensure manipulation in political "games" in the conduct of hybrid wars. The simultaneous interaction of social factors, influencing factors, the presence of communities in social networks forms a full-fledged socio-cyber-physical system capable of integrating real and virtual interactions to manage regional communities. The article proposes a method for predicting the assessment of social mutual influence between “formal” and “informal” leaders and regional societies. The proposed models make it possible to form not only a forecast of the influence of agents, but also the interaction of various agents, taking into account their formal and informal influences, the use of administrative resources, political moods of the regional society. This approach allows dynamic modeling based on impact and relationship analysis. The presented results of simulation modeling do not contradict the results of opinion polls and make it possible to form a set of measures that can be aimed at overcoming the negative impact on the regional society of both individual “leaders” and political parties. Analysis of the simulation results allows to increase both the political and social stability of the regional society, helps to prevent conflict moods and contradictions

Enhancement of Productivity of Random Sequences Generation for Information Protection Systems

The ways of enhancement of productivity of generation of random sequences, derived from physical sources for information protection systems were substantiated. This is necessary because today there is a rapid growth of technological capabilities and of rate indicators of implementation of various information services and applications, required by community. One of the main issues of the safe use of these services is to ensure information security, which requires the use of effective high­rate information protection systems and high­performance generation of random data sequences. In the course of conducting research with the aim of enhancing productivity, the features of conversion of actual noise processes, taking into consideration their non­stationarity and deviations from the probability distribution were analyzed. We proposed the ways to improve the methods of analog­to­digital conversion with the optimization of the scale dynamic range quantization and the pitch of discretization of a noise process over time. With a view to aligning statistical characteristics, the possibility of using the processing methods that enhance its statistical quality with economy of high­rate losses was explored. These are the method of sampling equally probable combinations (von Neumann – Elias –Ryabko – Matchikina) and the method of code processing (Santha – Vazirani) that provide an increased effectiveness due to code extension and involve conversion of the sequence: in the first method, with the use of equally probable combinations with rejection of unnecessary data; in the second method, without their rejection with the possibility of linear conversion. In order to optimize the conversion parameters at both stages of generation and to adapt these parameters to the peculiarities and changeability of characteristics of converted random processes, it was proposed to use feedbacks of converters' outputs with previous conversion elements. The adjustment of the specified parameters can be made during the generation based on the results of statistical analysis of the outputs of conversion stages. The obtained results are quite important, since their implementation in modern information protection systems will enable guaranteeing information security and safe usage of applications of the modern information service and the introduction of new applications

Practical Implementation of the Niederreiter Modified Crypto­code System on Truncated Elliptic Codes

On the basis of the practical implementation of the classic Niederreiter scheme for non-binary codes, a pattern has been identified for practical implementation –fixing the admissible position vectors of the plaintext transformation based on equilibrium coding. The obtained set of position vectors of the error vector with a fixed set of masking matrices (the recipient's private key) allows us to obtain the algorithm for decoding the classical Niederreiter crypto-code scheme on non-binary codes. For this, a modification of the crypto-code system (CCS) is necessary. It is proposed to use the additional parameter of key data – the initialization vector (the set of invalid position vectors of the error vector). To counter the Sidelnikov attacks, it is proposed to use modified (shortened) algebraic-geometric (elliptic) codes (MEC). For this, it is necessary to use the second additional initialization vector (the set of positions for shortening the error vector). Based on the modification of the classical Niederreiter scheme on non-binary codes, applied algorithms for generating and decrypting a cryptogram in the Niederreiter modified crypto-code system based on modified (shortened) elliptic codes and software are proposed. To confirm the profitability of the proposed crypto-code system, the results of the comparative evaluation of energy consumption for the implementation of the classical Niederreiter scheme on elliptic codes and the implementation of the proposed system on modified elliptic codes are presented. The results confirm the possibility of practical implementation of the Niederreiter crypto-code system based on the proposed algorithms. At the same time, the required level of cryptographic strength of the crypto-code system, protection of the cryptosystem against the Sidelnikov attacks and an increase in the rate of cryptographic transformations by 3-5 times compared with the classical Niederreiter scheme are guarantee

Development of the Model of the Antagonistic Agents Behavior Under a Cyber Conflict

The results of the development of the model of the antagonistic agents behavior in a cyber conflict are presented. It is shown that the resulting model can be used to analyze investment processes in security systems, taking into account the assumption that investment processes are significantly influenced by the behavior of parties involved in a cyber conflict.General approaches to model development are presented. First of all, the system of concepts, assumptions and limitations is formed, within the framework of which a mathematical model of behavior must be developed. Taking this into account, the mathematical model of the conflicting agents behavior, presented in the form of algebraic and differential equations, is developed. The developed model presents both the technical characteristics of the security system and the psychological characteristics of the participants in the cyber conflict, which affect the financial characteristics of the investment processes in cybersecurity systems. A distinctive feature of the proposed model is the simultaneous consideration of the behavior of the parties to a cyber conflict not as independent parties, but as agents mutually interacting with each other. The model also makes it possible to simulate the destabilizing effect of the confrontation environment disturbances on the behavior of the conflicting parties, changing the degree of vulnerability of the cybersecurity system along various attack vectors and the level of their success.Using the developed model, simulation modeling of the interacting agents behavior in a cyber conflict is performed. The simulation results showed that even the simplest behavior strategies of the attacking side (“the weakest link”) and the defense side (“wait and see”) make it possible to ensure information security of the business process loop.The developed model of interaction between the attacker and the defender can be considered as a tool for modeling the processes of the conflicting parties behavior when implementing various investment scenarios. The simulation results enable decision-makers to receive support regarding the direction of investment in the security of the business process loop