SCI Библиотека

Introduction/purpose: In this research, the influence of different turbulence models on the aerodynamic drag prediction of a generic spin-stabilized projectile was analyzed. The turbulence models chosen for investigation were one-equation Spalart-Allmaras, two-equation models Standard k-ε, Realizable k-ε, Standard k-ω and SST k-ω. The special sniper projectile M118 was selected for the study.

Methods: The flows around the projectile were numerically simulated using RANS equations intergrated into ANSYS Fluent software with different turbulence models. The numerical simulation was carried out at various Mach numbers to study the effect of turbulence models on the projectile aerodynamic drag prediction. The computational results were compared to the available experimental data to evaluate the ability of the turbulence models.

Results: The research results have shown that the turbulence models significantly affect the numerical simulation results. The Spalart-Allmaras turbulence model performs better than other models in the subsonic flow regime. The Standard k-ε, Realizable k-ε and SST k-ω models perform better than other models in the supersonic flow regime.

Conclusion: Computational Fluid Dynamics is a powerful tool to analyze the aerodynamics of flying bodies. By appropriately selecting turbulence models, the flow around flying bodies can be accurately investigated. In the case of generic ogive-cylinder-boattail projectiles, on the one hand, the Spalart-Allmaras model is suitable for subsonic flow, and the Standard k-ε, Realizable k-ε and SST k-ω models are recommended for the supersonic flight regime, on the other hand.

Introduction/purpose: The application of virtual reality (VR) and simulation technologies in military training offers cost-effective and versatile approach to training enhancement. However, prevalence of cybersickness (CS), characterized by symptoms such as nausea, limits their widespread use.

Methods: This study introduces objective parameters for the detection of CS using three-channel electrogastrogram (EGG) recording from one specific subject and assesses the independence and linear correlation for appropriate channel selection. The paper employs a 3-level discrete wavelet transformation (DWT) on the chosen channel to identify key parameters indicative of gastric disturbances. Furthermore, the paper investigates recovery from CS following VR and examines the application of unsupervised machine learning (ML) for segmenting EGG into baseline and CS, utilizing significant features previously identified.

Results and discussion: The analysis reveals no significant differences across EGG channels and moderate to low linear correlation between channel pairs. The feature selection demonstrates that the root mean square of the amplitude as well as the maximum and mean values of the power spectral density (PSD) calculated on all DWT coefficients, are effective for CS detection while the dominant EGG scale could not indicate CS for any level of decomposition. Furthermore, recovery signs appear approximately 8 minutes after the first VR experience supporting the idea of conducting multiple sessions the same day i. e., intensive VR-based training.

Conclusions: The unsupervised ML shows potential in identifying CSaffected EGG signal segments with feature extraction based on DWT, offering a novel approach for enhancing the prevention of CS occurrence in VR-based military training and other VR-related environments.

Introduction/purpose: Temperature and time-dependent effects such as concrete shrinkage and creep significantly affect the behavior of steel-concrete composite beams. Hence, taking into account the demands brought by these additional effects is necessary. This necessity has resulted in various theoretical and numerical research studies. This article proposes an analytical tool capable of predicting a new redistribution of stresses brought by the combined action of temperature and concrete shrinkage in composite steel-concrete beams in partial shear connection. In this work, the partial shear connection at the steel-concrete interface is taken into account according to the degree of connection (N/Nf).

Methods: This involves reformulating the model proposed in 2024 by Rahal et al analyzing the behavior of composite steel-concrete beams in full shear connection under the effect of temperature and concrete shrinkage. In this present study, the main contribution is the introduction of the effect of the connection degree (N/Nf) at the steel-concrete interface, thus leading to an analytical model capable of predicting additional stresses brought by shrinkage and temperature in composite steel-concrete beams in partial shear connection.

Results: When referred to the model proposed in 2024 by Rahal et al, the results from this current approach are satisfactory. They clearly show that the degree of connection significantly affects the forces brought about by the combined action of concrete shrinkage and temperature.

Conclusion: The results of the present approach and those of the existing model developed by Rahal et al are in good agreement. They clearly show the effect of concrete shrinkage and temperature as a function of the connection degree N/Nf on the behavior of composite steel-concrete beams.

Introduction/purpose: Wheeled armored combat vehicles are combat systems that are increasingly present in modern armed conflicts, especially in operations against asymmetric threats. The global wheeled armored vehicle market is constantly growing, which reflects their application in a wide range of missions and tasks of armed forces. The existence of numerous models of these vehicles with different technical and exploitation characteristics, along with the possibility of adaptation to specific needs, further complicates the choice of the most suitable alternative. The paper presents the case of solving the problem of selecting the most suitable multi-purpose medium-class wheeled armored vehicle with a 4x4 drive formula when choosing one of the four alternatives, using individual and group multi-criteria decision-making methods.

Methods: In the paper, the methods of multi-criteria decision making were applied to solve problems in the field of complex combat systems selection. Experts from the field of tactics with weapon systems have ranked the alternatives following the defined criteria using the AHP (Analytic Hierarchy Process) and the PROMETHEE II (Preference Ranking Organization Method for Enrichment Evaluations II) methods. The results obtained by individual decision making were subjected to the Condorcet method of group decision making to make a final decision.

Result: Selection of the most suitable vehicle by the defined criteria.

Conclusion: Solving the problem involves taking into account the views of military experts regarding the optimization of multiple criteria to provide the best performance vehicle suitable for use in various missions. The choice of a multi-purpose wheeled armored combat vehicle is a complex process influenced by numerous factors that cannot be analyzed objectively without the application of adequate mathematical models.

Introduction/purpose: The study of the theory of fuzzy sets was prompted by the presence of uncertainty as an essential part of real-world problems, leading Zadeh to address the problem of indeterminacy. The notion of fuzzy logic was introduced by Zadeh. Unlike traditional logic theory, where an element either belongs to the set or does not, in fuzzy logic, the affiliation of the element to the set is expressed as a number from the interval [0, 1].

Methods: The theory of a fixed point in fuzzy metric spaces can be viewed in different ways, one of which involves the use of fuzzy logic. Fuzzy metric spaces, which are specific types of topological spaces with pleasing ”geometric” characteristics, possess a number of appealing properties and are commonly used in both pure and applied sciences. Metric spaces and their various generalizations frequently occur in computer science applications. For this reason, a new space called a Pompeiu-Hausdorff fuzzy b-metric space is constructed in this paper. Results: In this space, some new fixed point results are also formulated and proven. Additionally, a general common fixed point theorem for a pair of multi-valued mappings in Pompeiu-Hausdorff fuzzy b-metric spaces is investigated. The findings obtained in fuzzy metric spaces, such as those discussed in the article of Shen, Y. et al. (2012. Fixed point theorems in fuzzy metric spaces. Applied Mathematics Letters, 25, pp.138-141), are generalized by the results in this paper, and additional specific findings are produced and supported by examples.

Conclusions: The study of denotational semantics and their applications in control theory using fuzzy b-metric spaces and Pompeiu-Hausdorff fuzzy b-metric spaces will be an important next step.

В брошюре автор критически рассматривает с точки зрения марксистской социально-психологической теории идейно-теоретические и социальные позиции одного из основателей неофрейдистского направления в психоанализе Э. Фромма.

Используя большой научно-теоретический и фактический материал, автор анализирует процесс социологизации психоанализа, проблему социального характера, роли «социально-бессознательного» в историческом становлении человека и общества, освещает исторический утопизм абстрактно-гуманистического «коммуникарного социализма» Э. Фромма.

В старину мужи науки располагали точным способом оценивать дарования святых и сочинителей. Про Эскобара, например, говорили, что учености у него на пять баллов, таланта — на четыре, а здравомыслия — на семь. Карамуэля ценили выше: за ученость — восемь, талант — шесть, а здравомыслие — тринадцать. Случись мне определять таким же способом достоинства нашего китайского философа, я без колебаний оценил бы его талант еще выше, а уж за ученость и здравомыслие смело поставил бы девятьсот девяносто девять баллов, ни на йоту не погрешив против истины.

В пособии показывается роль и значение проблемы практики в процессе формирования философии марксизма. Эта проблема рассматривается автором как центральный пункт революционного переворота в философии, как главная веха при переходе от идеализма и революционного демократизма к философии пролетариата. Книга написана на материалах анализа ранних произведений К. Маркса.

Предлагаемый сборник представляет собой результаты исследований ряда ученых вузов Ульяновской области. Статьи т. т. Винокурова Я. С., Деркачева И. З., Белозерцева В. И. являются результатом их работы над докторскими диссертациями, статьи т. т. Миронова Г. Ф., Никонова А. Н., Капканщикова Г. П., Лексина А. Ф. — над кандидатскими диссертациями.

В статьях рассматриваются различные проблемы истории философии, диалектического и исторического материализма. Ряд материалов посвящен специально вопросам диалектики развития социалистического общества. Авторы сборника выдвигают новые теоретические положения и дают практические рекомендации, некоторые из них, конечно, носят дискуссионный характер.

Научный сборник рассчитан на преподавателей общественных дисциплин, пропагандистов сети политического просвещения, студентов и всех, кто изучает проблемы марксистско-ленинской философии.

Прибавление. Можно, пожалуй, сказать, что в наше время философия не пользуется особенной благосклонностью; по крайней мере теперь уже не признают, как в прежнее время, что изучение философии должно быть необходимым введением и основой для всякого дальнейшего научного образования и профессиональных занятий.

Во всяком случае можно смело утверждать, что к философии природы в особенности относятся теперь с большой антипатией. Я не стану рассматривать здесь пространно, насколько справедливо такое предубеждение именно против философии природы; однако я не могу также обойти его совершенным молчанием.