Vol 18, No 2 (2020)

This paper continues the series of publications which aims to familiarize infocommunication technology specialists with the legacy of Leonard Jimmy Savage - one of the founders of the subjective theory of probability. His fundamental work, The Foundations of Statistics, extensively covers the topics of probability, risk assessment and the expected utility theory, all of which have prominent practical applications in the present day. This second paper, corresponding to the third chapter of the source material, analyzes correlations and divergences between the objective and subjective probability theories and lays out the author’s concept of subjective probability, as well as the related notions of qualitative, quantitative and conditional subjective probability. The paper explores possible ways of determining probability values using heuristic and empirical methods, series of controlled experiments and direct measurements. Unlike objective probability, subjective probability may be applied to the research and development of virtual systems, including new types of systems that have been theorized but never realized before.

The article considers the effect of bends and mechanical stresses caused by bending on the service life of optical fiber in the cable. It is shown that the bends distribution along the fiber length provides an unambiguous relationship with the distribution of mechanical stresses. A comparative review of modern methods used to control mechanical stresses in optical fibers is presented. The conclusion is drawn that the most promising and inexpensive method to implement for modern single-mode bend-insensitive fibers is the polarization reflectometry based on the analysis of information on the birefringence distribution along the optical fiber length. The factors leading to a change in the magnitude of birefringence during the operation of the optical fiber are determined. The conditions that are necessary to observe when measuring the birefringence distribution along the optical fiber length are presented

A fragment of a Software-Defined Networking architecture with the functionality of switches and controllers is described as the mathematical model of a multiphase queueing system with losses at each phase. In the Internet Engineering Task Force draft Address Resolution Delay in SDN (also see ITU Radiocommunication Sector M.2083-0), it was recommended to reduce network delay within a single Software-Defined Networking segment from 50 to 1 ms. This performance index depends considerably on the characteristics of the software and hardware system of Software-Defined Networks, as well as on the processes of interaction between the switches and the controller. However, the service time and hence the processing delays for packet flows are not regulated by the suppliers of switching equipment (e.g., Cisco Catalyst 3750 switches), which makes it difficult to determine the probabilistic and time characteristics of networks during the design stage and to formalize any suggestions on improving the performance of network elements. The models presented in this paper are based on the classical queueing theory and Laplace transforms. In this case, the relation between the stages of packets processing on network devices has little significance; therefore, the performance indices are obtained in terms of single-phase network parameters. The mean service time and the mean number of packets in a network are calculated as functions of the load of network devices. Also, analytical expressions for determining the mean loss ratio of network packets at each phase of processing by a switch are derived.

The scientific problem under consideration is associated with the problem of monitoring the integrity of the navigation field and ensuring the accuracy of positioning of robotic unmanned aerial vehicles under conditions of natural distortion of the navigation field and deliberate interference. The aim of the article is to develop a method that can reliably determine the fact of distortion of the navigation field and identify interference effects through the use of additional information obtained during the processing of navigation parameters in the navigation receiver. In order to identify the status of the GPS / GLONASS navigation field, the introduction of typical classes is proposed. The research uses a comparative assessment of the current results of navigational measurements with calculated values obtained by extrapolating a certain area with reliable measurements and a Bayesian probabilistic approach to solve the problem of detecting the fact of distortion of the navigation field and identifying the interference effect. The developed method allows to assess the state of the navigation field with high reliability and, when it is distorted, to identify the type of interference. The results are recommended to be used to improve the control algorithm of the unmanned aerial vehicles with the aim of expanding its functional capabilities in stand-alone operation under conditions of intentional and natural interference.

The auditory system of a person plays a leading role in their life and, above all, in the processes of information exchange based on sound signals, especially during oral speech. In this regard, many countries conduct studies on the characteristics of the human sound perception based on the creation of various types of models. These are necessary for improving hearing aids, developing systems for the automatic recognition of oral speech in artificial intelligence systems and optimizing the processing of speech signals during storage and transmission of voice messages. In the framework of this paper, a method has been developed for estimating the propagation velocity of disturbances along the basilar membrane created when the oval window is exposed. Fairly simple ideas about the properties that take place in the environment of the perilymph are used - the basilar membrane of physical processes.

The article provides the review of the threats to information security of flash drives, analyzes the FAT32 and NTFS file systems of flash drives and their vulnerabilities to malware. Features of viruses’ action algorithms on flash drives are highlighted in the article. The issue of flash drives security is still open. There are many effective ways to significantly reduce the possibility of infection of flash drives. After analyzing the drawbacks of the NTFS system, it shall be noted that this system requires a much larger amount of RAM compared to the FAT32 system, and that the data fragmentation also complicates the work of the system with medium size file directories. Moreover, the NTFS system has a relatively low performance rate when compared to the FAT32 system. If the flash drive is used more often with the home computer, then the home computer is chosen as the workstation and is provided with full access. Recording shall be prohibited for other computers. Today, there are many ways and methods of flash drives protecting, but the specifics of their use depend on the information store location and information value.

The article considers one of the serious problems of universities: the problem of choosing the direction of study. Every applicant who enters the university faces this problem. A wrong choice of direction leads to low student performance, possible abandonment of the profession and, consequently, to a decrease in the learning efficiency. To solve this problem, the article proposes the use of an intelligent decision support system. It allows to build a predictive model that links together the individual characteristics of applicants and the likelihood of a successful graduation in the chosen direction of study. The information received will be used to assist the applicant in choosing the direction of study. Having this information, the applicant will consciously approach the question of choosing their future specialization.