Biblio

This work introduces methods that unlock a series of applications for decision trees and neural networks in power system optimization. Capturing constraints that were impossible to capture before in a scalable way, we use decision trees (or neural networks) to extract an accurate representation of the non-convex feasible region which is characterized by both algebraic and differential equations. Applying an exact transformation, we convert the information encoded in the decision trees and the neural networks to linear decision rules that we incorporate as conditional constraints in an optimization problem (MILP or MISOCP). Our approach introduces a framework to unify security considerations with electricity market operations, capturing not only steady-state but also dynamic stability constraints in power system optimization, and has the potential to eliminate redispatching costs, leading to savings of millions of euros per year.

This article reports results about the development of the algorithm that allows to increase the information security of OFDM communication system based on the discrete-nonlinear Colpitts system with dynamic chaos. Proposed system works on two layers: information and transport. In the first one, Arnold Transform was applied. The second one, transport level security was provided by QAM constellation mixing. Correlation coefficients, Shannon's entropy and peak-to-average power ratio (PAPR) were estimated.

In the original algorithm for grey correlation analysis, the detected edge is comparatively rough and the thresholds need determining in advance. Thus, an adaptive edge detection method based on grey correlation analysis is proposed, in which the basic principle of the original algorithm for grey correlation analysis is used to get adaptively automatic threshold according to the mean value of the 3×3 area pixels around the detecting pixel and the property of people's vision. Because the false edge that the proposed algorithm detected is relatively large, the proposed algorithm is enhanced by dealing with the eight neighboring pixels around the edge pixel, which is merged to get the final edge map. The experimental results show that the algorithm can get more complete edge map with better continuity by comparing with the traditional edge detection algorithms.

When building the architecture of cyber defense systems, one of the important tasks is to create a methodology for current diagnostics of cybersecurity status of information systems and objects of information activity. The complexity of this procedure is that having a strong security level of the object at the software level does not mean that such power is available at the hardware level or at the cryptographic level. There are always weaknesses in all levels of information security that criminals are constantly looking for. Therefore, the task of promptly calculating the likelihood of possible negative consequences from the successful implementation of cyberattacks is an urgent task today. This paper proposes an approach of obtaining an instantaneous calculation of the probabilities of negative consequences from the successful implementation of cyberattacks on objects of information activity on the basis of delayed differential equation theory and the mechanism of constructing a logical Fuzzy function. This makes it possible to diagnose the security status of the information system.

Computer worms pose a major threat to computer and communication networks due to the rapid speed at which they propagate. Biologically based epidemic models have been widely used to analyze the propagation of worms in computer networks. For an air-gapped network with an insider threat, we propose a modified Susceptible-Exposed-Infected-Quarantined-Vaccinated (SEIQV) model called the Susceptible-Exposed-Infected-Quarantined-Patched (SEIQP) model. We describe the assumptions that apply to this model, define a set of differential equations that characterize the system dynamics, and solve for the basic reproduction number. We then simulate and analyze the parameters controlled by the insider threat to determine where resources should be allocated to attain different objectives and results.

Aiming at the shortcomings of the traditional network active security threat model that cannot continuously control the threat process, a network active security threat model based on offensive and defensive differential game is constructed. The attack and defense differential game theory is used to define the parameters of the network active security threat model, on this basis, the network security target is determined, the network active security threat is identified by the attack defense differential equation, and finally the network active security threat is quantitatively evaluated, thus construction of network active security threat model based on offensive and defensive differential game is completed. The experimental results show that compared with the traditional network active security threat model, the proposed model is more feasible in the attack and defense control of the network active security threat process, and can achieve the ideal application effect.

This paper considers the complex of models for the description, analysis, and modeling of group behavior by user actions in complex social systems. In particular, electoral processes can be considered in which preferences are selected from several possible ones. For example, for two candidates, the choice is made from three states: for the candidate A, for candidate B and undecided (candidate C). Thus, any of the voters can be in one of the three states, and the interaction between them leads to the transition between the states with some delay time intervals, which are one of the parameters of the proposed models. The dynamics of changes in the preferences of voters can be described graphically on diagram of possible transitions between states, on the basis of which is possible to write a system of differential kinetic equations that describes the process. The analysis of the obtained solutions shows the possibility of existence within the model, different modes of changing the preferences of voters. In the developed model of stochastic cellular automata with variable memory at each step of the interaction process between its cells, a new network of random links is established, the minimum and the maximum number of which is selected from a given range. At the initial time, a cell of each type is assigned a numeric parameter that specifies the number of steps during which will retain its type (cell memory). The transition of cells between states is determined by the total number of cells of different types with which there was interaction at the given number of memory steps. After the number of steps equal to the depth of memory, transition to the type that had the maximum value of its sum occurs. The effect of external factors (such as media) on changes in node types can set for each step using a transition probability matrix. Processing of the electoral campaign's sociological data of 2015-2016 at the choice of the President of the United States using the method of almost-periodic functions allowed to estimate the parameters of a set of models and use them to describe, analyze and model the group behavior of voters. The studies show a good correspondence between the data observed in sociology and calculations using a set of developed models. Under some sets of values of the coefficients in the differential equations and models of cellular automata are observed the oscillating and almost-periodic character of changes in the preferences of the electorate, which largely coincides with the real observations.

There were many researches about the parameter estimation of canonical dynamic systems recently. Extended Kalman filter (EKF) is a popular parameter estimation method in virtue of its easy applications. This paper focuses on parameter estimation for a class of canonical dynamic systems by EKF. By constructing associated differential equation, the convergence of EKF parameter estimation for the canonical dynamic systems is analyzed. And the simulation demonstrates the good performance.

The paper considers the general structure of Pseudo-random binary sequence generator based on the numerical solution of chaotic differential equations. The proposed generator architecture divides the generation process in two stages: numerical simulation of the chaotic system and converting the resulting sequence to a binary form. The new method of calculation of normalization factor is applied to the conversion of state variables values to the binary sequence. Numerical solution of chaotic ODEs is implemented using semi-implicit symmetric composition D-method. Experimental study considers Thomas and Rössler attractors as test chaotic systems. Properties verification for the output sequences of generators is carried out using correlation analysis methods and NIST statistical test suite. It is shown that output sequences of investigated generators have statistical and correlation characteristics that are specific for the random sequences. The obtained results can be used in cryptography applications as well as in secure communication systems design.

In this paper, we focus on the principal-agent problems in continuous time when the participants have ambiguity on the output process in the framework of g-expectation. The first best (or, risk-sharing) type is studied. The necessary condition of the optimal contract is derived by means of the optimal control theory. Finally, we present some examples to clarify our results.

Wireless sensor networks (WSNs) are prone to propagating malware because of special characteristics of sensor nodes. Considering the fact that sensor nodes periodically enter sleep mode to save energy, we develop traditional epidemic theory and construct a malware propagation model consisting of seven states. We formulate differential equations to represent the dynamics between states. We view the decision-making problem between system and malware as an optimal control problem; therefore, we formulate a malware-defense differential game in which the system can dynamically choose its strategies to minimize the overall cost whereas the malware intelligently varies its strategies over time to maximize this cost. We prove the existence of the saddle-point in the game. Further, we attain optimal dynamic strategies for the system and malware, which are bang-bang controls that can be conveniently operated and are suitable for sensor nodes. Experiments identify factors that influence the propagation of malware. We also determine that optimal dynamic strategies can reduce the overall cost to a certain extent and can suppress the malware propagation. These results support a theoretical foundation to limit malware in WSNs.