PhD Air Force Science Center* O. T y m o c h k o Doctor of Technical Sciences, Рrofessor Department of Navigation and Motion Control* M. P a v l e n k o Doctor of Technical Sciences, Рrofessor Department of Mathematical and Software of Automated Control Systems* O. D m i t r i i e v PhD** M. Z h y v y t s k y i PhD, Associate Рrofessor** N. G o n c h a r e n k o
The transfer of information by telecommunication channels is accompanied by message hashing to control the integrity of the data and confirm the authenticity of the data. When using a reliable hash function, it is computationally difficult to create a fake message with a pre-existing hash code, however, due to the weaknesses of specific hashing algorithms, this threat can be feasible. To increase the level of cryptographic strength of transmitted messages over telecommunication channels, there are ways to create hash codes, which, according to practical research, are imperfect in terms of the speed of their formation and the degree of cryptographic strength. The collisional properties of hashing functions formed using the modified UMAC algorithm using the methodology for assessing the universality and strict universality of hash codes are investigated. Based on the results of the research, an assessment of the impact of the proposed modifications at the last stage of the generation of authentication codes on the provision of universal hashing properties was presented. The analysis of the advantages and disadvantages that accompany the formation of the hash code by the previously known methods is carried out. The scheme of cascading generation of data integrity and authenticity control codes using the UMAC algorithm on crypto-code constructions has been improved. Schemes of algorithms for checking hash codes were developed to meet the requirements of universality and strict universality. The calculation and analysis of collision search in the set of generated hash codes was carried out according to the requirements of a universal and strictly universal class for creating hash codes
In the article the analysis of existent basic methods of determining the weight of body of cosmonauts and objects small weight is conducted in the conditions of weightlessness, and their features of application are similarly exposed. The most comfortable and perspective method of determining the inertial weight of body in the conditions of weightlessness the use of different sort of oscillators and devices, that allow to measure the parameters of body of cosmonaut (small weight of devices and others like that), that hesitates, is considered. It is possible to use dependence of period of vibrations of spring on b.w. of cosmonaut envisaged on her and others like that. The measuring device of weight of «ИМ-01М», his technical descriptions, composition and principle of action, is considered. Such measuring device it maybe to complement the system of weighing of astronauts and cosmonauts on the method of Karmelo Velardo, that allows to get measuring (form and sizes of cosmonaut and his motions) given about the depth of object. The object of research is oscillators and devices, that allow to measure parameters bodies of cosmonaut and objects small weight, that hesitate. The subject of research is a mathematical vehicle on determination of frequency of eigentones dynamic system. The research aims is development of method of control of frequency of eigentones for determining the weight of body of cosmonaut and objects small weight in the conditions of weightlessness. Conclusions. The method of determining the weight of body of cosmonauts and objects small weight in the conditions of weightlessness and method of his realization are offered on the change of frequency of eigentones dynamic system devices. Analytical expressions for the calculation of frequency of eigentones dynamic system devices and corresponding charts are presented. A spring-gravimetric device is worked out for realization of measuring. A chart technical decision over of device is brought, his composition and principle of action are exposed. A device is able to define weight of control object, his state (his heterogeneity, presence of liquid filler, parts that hesitate and others like that).
The transition of an astronaut into zero gravity leads to a certain restructuring of the body, including the redistribution of fluid flows in it. The process of dehydration of the body is stimulated, the astronaut loses weight. Knowledge of the regularities of changes in an astronaut's body weight, keeping it within normal limits thanks to a rational load distribution, rest, physical exercises, and a well-thought-out diet are extremely necessary in order to provide the astronaut with the most favorable conditions for adaptation in zero gravity, as well as to better prepare him for his return to Earth. Returning materials for scientific research and experiments, as well as equipment, from the space station to Earth also requires high-precision determination of the low weight of objects. The object of the research is an experimental unit that allows measuring the weight (parameters) of the astronaut’s body and the small weight of objects (equipment, devices, etc.) that oscillate. The subject of research is the frequency of natural oscillations of the dynamic system. The purpose of scientific work is the development of an experimental unit for determining the weight of the astronaut’s body and the low weight of objects in zero gravity. Conclusions. An experimental setup for determining the body weight of astronauts and the low weight of objects (control objects – СО) in zero gravity is proposed. For high-precision determination of the weight of the СО in zero gravity, the natural frequency (NF) was chosen as a diagnostic parameter. In the experimental installation, the weight of the OC is determined by changing the NF of the dynamic system "control object – moving anchor" depending on the attached weight of the СO. The essence of the work of the experimental unit is revealed, and its general appearance and structural scheme are presented.
In this article effective approach of the study of high-stress concentration at closely placed holes in wing bearing area (in anisotropic plates) is proposed. It is based on the boundary integral equation method with the additional use of the asymptotic method. The simplicity, precision of the approach and the stability of the solution are illustrated in the calculation of stresses in the plate with a circular hole, an elliptical hole, elongated holes, a plate with two closely spaced elliptical holes
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