Unknown Moments Research Articles

ВОЗДУШНАЯ РАЗВЕДКА СОВЕТСКОГО ФЛОТА В ЧЕРНОМОРСКОМ РЕГИОНЕ В ИЮНЕ–АВГУСТЕ 1941 ГОДА

The quantitative and qualitative composition of the reconnaissance aviation of the Air Force of the Black Sea Fleet and the Danube military flotilla on the eve and in the initial period of the Great Patriotic War, the main tasks and directions of its actions, the general characteristics of the organizational work of intelligence departments and the direct performance of aerial reconnaissance in the specific conditions of the outbreak of war are revealed. The characteristics of the technical side of aviation exploration are given, the difficulties of organization and problems during flights are considered. A number of previously unknown moments in the history of the fleet have been discovered, and some circumstances of known events have been clarified.

Ethnography under Authoritarianism: Notes from Medical Anthropological Fieldwork

What is perceived today as “living in an unknown moment” with global pandemics and ecological disasters has long become the “new normal” that structures everyday life at the margins of Europe and the Middle East, particularly in places with rising authoritarian regimes. As scholars working in and on Turkey, for instance, we have witnessed or experienced firsthand several moments of crisis over the recent years. We have seen the collapse of peace negotiations between the Turkish state and the Kurdistan Worker's Party (Partiya Karkeren Kurdistane; PKK) in 2015 and the resulting surge in state violence in Turkey's Kurdistan, the 2016 coup attempt against the Justice and Development Party (Adalet ve Kalkınma Partisi; AKP) government by the Gülen movement, and the long-standing suppression, criminalization, and incarceration of dissent affecting, among others, students, politicians, journalists, and academics. These divergent yet interlinked moments of crisis have reshaped and often complicated, if not completely stopped, our research as ethnographers of Turkey. These moments of crisis have also pushed us to develop creative strategies and analytics to continue our fieldwork and provided opportunities to hone our research questions and methodologies in more nuanced ways.

An improved algorithm for solving inverse problems of the dynamics of robotic devices at SCAS KIDYM

The paper presents the results of studies of an analytical algorithm for constructing a resolving system of linear equations to determine the driving forces and moments in the links of robotic devices of arbitrary structure during movement. This algorithm is implemented as an analytical algorithm in a special computer algebra system (SCAS) KiDyM, on the basis of which numerical calculations of the specified forces and moments are generated in the process of performing work processes, positioning mechanisms in the required positions, parking movements, etc. The KiDyM software package is used to solve mechanics problems of a wide class of discrete mechanical systems of arbitrary structure and type of motion for engineering and scientific calculations. A theoretical justification for the developed new approach, analytical and numerical proof of its effectiveness from the point of view of the process of automatically obtaining resolving equations, computational efficiency and accuracy of results are presented. The proposed algorithm is the result of the development of an algorithm that was previously implemented in SCAS KiDyM and was similar in purpose. Unlike the previously implemented algorithm, which generates a resolving system of equations after constructing the dynamic equations, the new algorithm is built into the process of generating dynamic equations - it sorts the model elements - inertial, dissipative, elastic and force elements of known forces and moments form the right side, and force elements with unknown forces and moments, they form a matrix of the left side of equations that solve the inverse problem of dynamics. The article gives a comparative analytical conclusion of one and another algorithm and shows the coincidence of the resulting equations. Also, using examples of calculations of the inverse problem of the dynamics of a portal crane and two 6-degree manipulators, the advantages of the new approach are shown.

Estimates of matrix solutions of operator equations with random parameters under uncertainties

We investigate problems of estimating solutions of linear operator equations with random parameters under conditions of uncertainty. We establish that the guaranteed rms estimates of the matrices are found as solutions of special optimization problems under certain observations of the system state. As the output signals of the system, we have observations that are described by linear functions from the solutions of such equations with random right-hand sides, which have unknown second moments. Under the condition that the observation second moments of the right-hand parts and errors belong to certain sets, it is proved that the guaranteed estimates are expressed through solutions of operator equation systems. When the linear operator is given by the scalar product of rectangular matrices, a quasi-minimax estimate and its error are constructed. It is shown that the quasi-minimax estimation error tends to zero when the number of observations tends to infinity. An example of calculating the guaranteed rms estimate of the matrix's trace, which is a solution of a matrix equation with a random parameter, is given.

Handedness anomaly in a non-collinear antiferromagnet under spin-orbit torque.

Non-collinear antiferromagnets are an emerging family of spintronic materials because they not only possess the general advantages of antiferromagnets but also enable more advanced functionalities. Recently, in an intriguing non-collinear antiferromagnet Mn3Sn, where the octupole moment is defined as the collective magnetic order parameter, spin-orbit torque (SOT) switching has been achieved in seemingly the same protocol as in ferromagnets. Nevertheless, it is fundamentally important to explore the unknown octupole moment dynamics and contrast it with the magnetization vector of ferromagnets. Here we report a handedness anomaly in the SOT-driven dynamics of Mn3Sn: when spin current is injected, the octupole moment rotates in the opposite direction to the individual moments, leading to a SOT switching polarity distinct from ferromagnets. By using second-harmonic and d.c. magnetometry, we track the SOT effect onto the octupole moment during its rotation and reveal that the handedness anomaly stems from the interactions between the injected spin and the unique chiral-spin structure of Mn3Sn. We further establish the torque balancing equation of the magnetic octupole moment and quantify the SOT efficiency. Our finding provides a guideline for understanding and implementing the electrical manipulation of non-collinear antiferromagnets, which in nature differs from the well-established collinear magnets.

WOMEN IN THE HISTORY OF THE EARLY MODERN TIME – OUTSTANDING PERSONALITIES OF THE DRUGETH FAMILY (II)

Due to the development of the science of history and the research on the „female theme”, the way of looking at the past and the future is also undergoing a significant change. In our study, through the study of general and specific examples, we would like to present the social conditions in which aristocratic women lived, worked, gave birth, raised children, and managed estates in the second half of the 17th century. Many of them can be said to have withstood the difficult conditions of those times in an exemplary manner. In the society of those times, all people had their own duties and responsibilities with regard to their gender and age. In this study, we examine what opportunities were available to early modern aristocratic women in terms of social and community relations, family life and building a marriage inserted into the historical events of those times. We complete it by examining the life paths and career models of the women who entered the Homonnai Drugeth family through marriage, highlighting various aspects of their lives. From the reader’s point of view, it may seem excessive to outline the social conditions of those times, however, without knowledge of them, the formulation of women’s roles of those times may be incomplete. In the second half of the 17th century, the religious structure of the region also changed significantly, so the aristocratic women of those times (unlike their predecessors) already supported the spread of re-Catholicization. What roles did the aristocratic women of that period play in contemporary Hungarian society and in their narrower environment? The framework for this was mainly set by her family and the inherited relationship system into which she was born. In accordance with social expectations, the aristocratic woman of those times increased the prestige of her family through marriage as well as ensured financial security of her future descendants with a prosperous marriage. Since women did not (could not) participate widely and officially in the formation of politics and everyday public life, there are much fewer and more diverse sources about them than about men. In these, we can find references to them mainly as wives, daughters, brides and mothers. Despite this (precisely due to their social status), women also had a significant informal influence on political life. That is why it is important to study the life path of women of those times, because without this knowledge our image of the society of those times would be incomplete. The present study may become one of the important building blocks, which, in addition to supplementing incomplete biographical data, will try to present the social roles played by these women. The article is a continuation of a scientific study devoted to the current problem - the analysis of the role of women of noble origin in the early modern period in the socio-political and socio-economic relations of the northeastern part of the Hungarian Kingdom. The article summarizes the study new aspects of the family history through the unknown moments of the life path of the Drugeth women (Katalin Nádasdy, Anna Jakusich, Mária Esterházi Mária, Terézia Keglevich) and new give aspects of the family's history.

Analytical modeling on the vibration response of a beam‐stiffened Mindlin thick plate with free boundary conditions

AbstractThis paper presents a new analytical solution for the vibration response of a beam‐stiffened Mindlin plate having a completely free boundary condition by utilizing a finite cosine integral transform. In the solution, the unknown coupling force and moments at the beam/plate interface and the unknown modal constants from the integral transform are determined by the continuity and compatibility conditions at the interface as well as the boundary conditions. It provides an easily implemented tool for exploring complex edge value problems for a class of higher‐order partial differential equations represented by fully free‐stiffened Mindlin thick plates. The validity of the model is evaluated by comparing the calculated free and forced vibration responses of the beam‐stiffened plate with those calculated using a beam‐stiffened thin plate and those from finite element analysis.

Unified integral transform solution for vibration analysis of ribbed plate

This paper presents a unified integral transform solution for the analysis of free and forced vibration of ribbed rectangular plate with arbitrary classical boundary conditions, whereas previous integral transform techniques have mainly focused on the analysis of the mechanical behavior of bare plates. The one- and two-dimensional integral transform techniques are applied to the higher-order partial differential governing equations of the beams and the plates, respectively, which are transformed into a system of linear algebraic equations after a rigorous derivation. The unknown coupling force and moment are determined by the compatibility conditions at the beam-plate coupling interface to obtain a unified solution scheme for ribbed plates with arbitrary classical boundary conditions. Good agreements are found between the results of analytical solution, finite element analysis and literature. Moreover, experiments on vibration analysis of a ribbed plate with completely free boundary conditions are conducted to further verify the validity and accuracy of the unified solution scheme. The effect of rib on the vibration response of rectangular plates is also investigated. It is shown that the vibration is controlled by the plate stiffness when the rib plays as a mass loading. The proposed unified analytical solution can be widely used to provide theoretical guidance for the vibration prediction of various structures with ribbed plates, such as offshore platforms, high-speed carriages, and aircraft wings.

Moment-Based Model Predictive Control of Autonomous Systems

Great efforts have been devoted to the intelligent control of autonomous systems. Yet, most of existing methods fail to effectively handle the uncertainty of their environment and models. Uncertain locations of dynamic obstacles pose a major challenge for their optimal control and safety, while their linearization or simplified system models reduce their actual performance. To address them, this paper presents a new model predictive control framework with finite samples and a Gaussian model, resulting in a chance-constrained program. Its nominal model is combined with a Gaussian process. Its residual model uncertainty is learned. The resulting method addresses an efficiently solvable approximate formulation of a stochastic optimal control problem by using approximations for efficient computation. There is no perfect distribution knowledge of a dynamic obstacle's location uncertainty. Only finite samples from sensors or past data are available for moment estimation. We use the uncertainty propagation of a system's state and obstacles' locations to derive a general collision avoidance condition under tight concentration bounds on the error of the estimated moments. Thus, this condition is suitable for different obstacles, e.g., bounding box and ellipsoid obstacles. We provide proved guarantees on the satisfaction of the chance-constraints corresponding to the nominal yet unknown moments. Simulation examples of a vehicle's control are used to show that the proposed method can well realize autonomous control and obstacle avoidance of a vehicle, when it operates in an uncertain environment with moving obstacles. It outperforms the existing moment methods in both performance and computational time.

A Fault Detection Method for a Practical Electro-Hydraulic Variable-Displacement Pump With Unknown Swashplate Moment

Electro-hydraulic controlled variable-displacement pump (EHVDP) is a power source of the hydraulic system, which is extensively used in the electro-hydraulic system due to the high efficiency and controllability. Thus, for a good operation of the hydraulic system, effective fault diagnosis techniques are crucial to avoid unexpected breakdown and failure. However, the data-driven fault diagnosis methods, which are commonly adopted in axial piston pumps, suffer from a lack of considerably effective data. Modelling uncertainty due to the swashplate moment has not been adequately considered, though some attempts have been made for the model-based methods. In this paper, the pressure transition is assumed to simplify the swashplate moment. A Kalman filter with unknown input for the EHVDP is used to estimate the additional uncertainty due to the simplification of the swashplate moment. A cumulative sum (CUSUM) based residual evaluation is utilized to detect the fault of the EHVDP. The test bench has been established and three typical failure modes of the EHVDP, including the control valve, displacement regulation mechanism, and rotating group are investigated by the experiments. Experimental results under different working conditions validate the effectiveness of the proposed fault detection method. Comparative results show the superiority of the proposed method in sensitivity and rapidity over the general method not considering unknown swashplate moment.

WOMEN IN THE HISTORY OF THE EARLY MODERN TIME – OUTSTANDING PERSONALITIES OF THE DRUGETH FAMILY

The article is devoted to today's actual problem - the analysis of the role of women of noble origin in early modern times in the socio-political and socio-economic relations of the northeastern part of the Hungarian kingdom. Although the study of gender (women's) history has recently gained momentum and become popular, this problem has been little studied in Ukrainian and Hungarian historical science and requires further research. The article presents an analysis of historical documents from the 16th to the first half of the 17th century with a special emphasis on the female characters of the Drugeth family. During the writing of the article, the author encountered various problems, including lack of basic biographical data. The problem is also the fact that the available data are incomplete and contradictory, and the family (genealogical) trees are compiled incorrectly, so the author proposes to introduce a new, refined version of the Drugeth genealogy into scientific circulation. Further archival research enables the author to slowly but surely write a more plausible history of the family. The article summarizes the study new aspects of the family history through the unknown (or yet published) moments of the life path of the Drugeth women (Anna Báthory, Erzsébet Perényi, Margit Zrínyi, Fruzsina Török, Erzsébet Rákóczi, Fruzsina Dóczy) and new give aspects of the family's history, and characteristics of their impact on socio-political, economic and religious changes in the region through the prism of Hungarian legislation. In our opinion, thanks to the research, we made an additional contribution to the study of some unknown fragments of the history of the Drugeth family. The article analyzes the concept of Transcarpathian historians regarding the decisive influence of aristocratic women on the religious practice (religious conversion) of noble families during the Reformation and then the Counter-Reformation. It has been proven that Drugeth women had a significant influence on their environment, including on the formation of socio-political and socio-economic relations. In our opinion, during the writing of the article, an additional contribution was made to the study of unknown fragments of the history of the Drugeth family.

Chaotic attitude synchronization and anti-synchronization of master-slave satellites using a robust fixed-time adaptive controller

It is well known that the satellite attitude motion exhibits the chaotic phenomenon. This article addresses the challenging problem of chaotic attitude synchronization and anti-synchronization for master-slave satellites under unknown moments of inertia and disturbance torques. First, a fixed-time adaptive synchronization controller is designed by combining the fixed-time control technique and adaptive control technique. The parametric adaptation laws are adopted to identify the unknown parameters in the synchronization error system. Benefiting from the adaptive identifications, the proposed controller is highly robust to unknown moments of inertia and disturbance torques. The practical fixed-time stability of the resulting closed-loop system is strictly achieved. The proposed controller can guarantee all error variables in the closed-loop system regulate to the small residual sets around zero in fixed time. Then, a fixed-time adaptive anti-synchronization controller is developed in a similar way. Finally, simulations studies are conducted to demonstrate the effectiveness and excellent control performance of the proposed controllers.

Time-Optimal Control Problem of Two Non-Synchronous Oscillators

The time-optimal control problem for a system consisting of two non-synchronous oscillators is considered. Each oscillator is controlled with a shared limited scalar control. The objective of the control is to accelerate the oscillatory system to a given specific position, where the first oscillator must have non-zero phase coordinates, but the second one must remain motionless at the terminal moment. For an arbitrary number of unknown switching moments that determine the optimal relay control, the necessary extremum conditions in the form of nonlinear matrix equalities are proposed. The study of the necessary/sufficient conditions of the extremum made it possible to describe the reachability set in the phase space of the first oscillator, to find an analytical form of the curve corresponding to the two-switching control class, which also separates the reachability set of the three switching-control class. The corresponding theorems are proved and the dependence of the criteria on control constraints is shown. Matrix conditions for different classes of control switchings are found. All of the obtained analytical results are numerically validated and illustrated with mathematical modeling.

Event-triggered attitude maneuver control of spacecraft under angular velocity constraints

Considering the spacecraft attitude system subject to angular velocity constraints, limited communication resources, the inaccurate moment of inertia, and external interference, a neural network-based adaptive event-triggered attitude maneuver control scheme is proposed. Specifically, the angular velocity constraint is first transformed into the performance boundary constraint based on the prescribed performance method, and then the equivalent error model of the attitude system is established using error transformation, which tactfully transforms the attitude maneuver control problem with angular velocity constraints into the state-bounded stability control problem of the unconstrained error system. Subsequently, by applying the radial basis function neural network, an adaptive online updating law is designed to approximate the uncertainty term caused by the unknown moment of inertia online. Meanwhile, considering the limited communication resources, a unified time-varying event-triggered mechanism is developed by establishing the explicit relationship between the trigger control signal and the real-time control one. The control command and the adaptive law are synchronously updated once the trigger condition is satisfied. By doing so, the frequent network signal transmissions between the controller and the actuator are reduced significantly. In addition, the time-varying term in the event-triggered mechanism strictly guarantees that no Zeno phenomenon occurs. The simulation results show that the proposed attitude control algorithm can achieve the specified attitude maneuver task with higher accuracy, stability, and robustness and reduce frequent control signal updates by about 97.50%, significantly reducing the on-board communication burden.

Adaptive Control With Unknown System Dynamics Estimator for Quadrotor Attitude Tracking

This paper presents an adaptive control scheme via combining with an unknown system dynamics estimator (USDE) for attitude control of quadrotors subject to both parametric uncertainties and external disturbances. The presented controller is designed by effectively merging an adaptive control with an USDE via backstepping, where the extraneous uncertainties are addressed by USDE, and the adaptive law driven by tracking errors accounts for identifying unknown inertial moment constants. The unique characteristic is that a reinforced attitude controlling can be realized benefiting from the separate handling of parametric uncertainties and disturbances via an adaptive updating and a concise disturbance observation, significantly releasing the learning load of USDE and a high gain can be avoided in feedback loops. Meanwhile, Lyapunov analysis demonstrates that all error variables are uniformly ultimately bounded in the closed-loop system. Eventually, simulations substantiate the utility of suggested control strategy.

Efficiency of detection of an ultra-wideband signal of unknown shape with unknown moments of appearance and disappearance of the signal received against the background of narrowband interference and Gaussian white noise

Efficiency of detection of an ultra-wideband signal of unknown shape with unknown moments of appearance and disappearance of the signal received against the background of narrowband interference and Gaussian white noise

Coupled vibro-acoustic analysis of submerged double cylindrical shells with stringers, rings, and annular plates in a symplectic duality system

A wave propagation analysis model of a submerged double cylindrical shell with stringers, rings, and annular plates is established in a symplectic duality system, accounting for acoustic-structure coupling. First, the vibration problem of the double cylindrical shell with stringers is introduced into the symplectic duality system by the Hamiltonian function. The wave propagation parameters and wave shape matrices with symplectic orthogonal relations are obtained by solving a symplectic eigenvalue problem. Then, according to the wave propagation relations, the wave amplitudes are derived by accounting for unknown forces, moments, and pressures induced by the rings, annular plates, and fluid. Finally, the vibration and acoustic responses are obtained through the wave shape matrices and wave amplitudes. In this study, the wave propagation parameters and wave shape matrices are calculated in the symplectic dual space, and the axial thickness discontinuity induced by the rings and annular plates is addressed through the cutting of the wave propagation path. Consequently, the convergence is not affected by the number of rings and annular plates, and the method achieves higher calculation accuracy and efficiency compared with the modal superposition method based on analytical beam functions. The parameter analysis indicates that proper combinations of the number and thickness of the annular plates can significantly reduce the vibro-acoustic responses for the same total mass of the annular plates, while changing the number of rings and stringers cannot. When the inner and outer cylindrical shells lose the same mass, altering the thickness of the outer shell has a greater impact.

Robust Prescribed Performance Control of Uncertain Vehicle Lateral System under State Constraints

In the study of the zero-error tracking control problem for vehicle lateral control systems under full-state constraints and nonparametric uncertainties, the zero-error tracking control problem is presented in this paper. A neural adaptive tracking control scheme is proposed by combining the error transformation of the vehicle lateral control system with the barrier Lyapunov function, which realizes that the tracking error of the vehicle lateral control converges to a prescribed compact set at a controllable or specified convergence rate in a specified finite time. The scheme has the following significant characteristics: 1) Based on the Nussbaum gain, the preset new energy finite-time control algorithm, the tracking error of the vehicle lateral control system with non-parametric uncertainty and external disturbance decreases to zero with t → ∞. In addition, it also has the control ability to cope with the presence or even unknown moment of inertia of the system. 2) Barrier Lyapunov function (BLF) ensures the bounded input of the neural network during the whole system envelope, and ensures the stable learning and approximation of the neural network. Furthermore, the bounded stability of the closed-loop system is proved by Lyapunov analysis. Finally, the effectiveness and superiority of the proposed control method are verified by simulation.

Spatial Birth–Death–Move Processes: Basic Properties and Estimation of their Intensity Functions

AbstractMany spatiotemporal data record the time of birth and death of individuals, along with their spatial trajectories during their lifetime, whether through continuous-time observations or discrete-time observations. Natural applications include epidemiology, individual-based modelling in ecology, spatiotemporal dynamics observed in bioimaging and computer vision. The aim of this article is to estimate in this context the birth and death intensity functions that depend in full generality on the current spatial configuration of all alive individuals. While the temporal evolution of the population size is a simple birth–death process, observing the lifetime and trajectories of all individuals calls for a new paradigm. To formalise this framework, we introduce spatial birth–death–move processes, where the birth and death dynamics depends on the current spatial configuration of the population and where individuals can move during their lifetime according to a continuous Markov process with possible interactions. We consider non-parametric kernel estimators of their birth and death intensity functions. The setting is original because each observation in time belongs to a non-vectorial, infinite dimensional space and the dependence between observations is barely tractable. We prove the consistency of the estimators in the presence of continuous-time and discrete-time observations, under fairly simple conditions. We moreover discuss how we can take advantage in practice of structural assumptions made on the intensity functions and we explain how data-driven bandwidth selection can be conducted, despite the unknown (and sometimes undefined) second order moments of the estimators. We finally apply our statistical method to the analysis of the spatiotemporal dynamics of proteins involved in exocytosis in cells, providing new insights on this complex mechanism.

ВИЯВЛЕННЯ ТА ОЦІНЮВАННЯ КІБЕРАТАК В ІНФОРМАЦІЙНИХ МЕРЕЖАХ ІЗ ВИПАДКОВИМ МОМЕНТОМ ПОЯВИ

Detection, prevention or significant impediment to cyberattacks (CA) is one of the central areas of cybersecurity in information networks. Determining the generalized requirements for cyber protection of information networks from cyberattacks on information and assessing the degree of their security are quite difficult tasks. There are real possibilities for unforeseen situations as a result of cyberattacks, leading to the loss of information or to its loss and loss of information network. The concept of cybersecurity of the information network on the basis of threats from cyberattacks should determine the necessary tools, methods and procedures for detection and evaluation of cyberattacks in networks. Therefore, for the effective functioning of information networks in modern conditions and means of their protection, as well as for the reliable detection and evaluation of cyberattacks, it is necessary to develop new approaches and methods, their implementation. Some results related to joint sequential detection and evaluation were obtained in [3]. As follows from [3], in the general case, is not possible to find a constructive solution even in the two-alternative problem. Losses in the process of recognition (detection) and evaluation of a cyberattack depend on both errors in its detection and inaccuracy of evaluation, which will not provide adequate response, and there is a problem of joint development and evaluation [1, 2]. Therefore, we will try to solve this problem of multi-alternative sequential detection and evaluation of a cyberattack with a random moment of its occurrence. Consistent detection and evaluation procedures are generally more efficient than inconsistent ones. Therefore, it is important and urgent to find optimal, consistent or close to them procedures that will increase the cybersecurity of information. The purpose of the article is to find optimal, consistent or close to them procedures that will increase the cybersecurity of information. Based on the probabilistic assessment, the optimal, sequential or close to them procedures are revealed in the work, which allow to increase the cybersecurity of information. The problem to build the optimal N-truncated sequential procedure for joint detection of cyberattacks (CA) and to estimate the moment of its occurrence in the loss function was solved. Statistics related to the average volume of the forecast (UOP) are analyzed. A general view of the optimal procedure for sequential detectionevaluation of a cyberattacks with an unknown moment of occurrence during these losses is proposed. Thus, if the optimal procedure is based on comparing one-dimensional statistics Ln c with a deterministic threshold for solving the problem of detection without estimating the moment of cyberattacks or for solving the problem of detection and evaluation separately, then the optimal areas for stopping and continuation of observations are determined in three-dimensional space for solving these problems.