Size effects in multiferroic BiFeO3 nanodots: A first-principles-based study

An effective Hamiltonian scheme is developed to investigate structural and magnetic properties of BiFeO3 nanodots under short-circuit-like electrical boundary conditions. Various striking effects are discovered. Examples include (a) scaling laws involving the inverse of the dots' size for the magnetic and electric transition temperatures; (b) the washing out of some structural phases present in the bulk via size effects; (c) the possibility of tailoring the difference between the Neel and Curie temperatures, by playing with the size and electrical boundary conditions; and (d) an universal critical thickness of the order of 1.6 nm below which the dots do not possess any long-range ordering for the electrical and magnetic dipoles, as well as, for the oxygen octahedral tiltings.Comment: 3 figure

Special Aspects of DC Air Plasma Torch’s Operating Modes under Turbulent Flow Conditions

The article is dedicated to the analysis of plasma flow turbulization processes inside DC air plasma torches. The influence of plasma torch’s arc current and plasma gas flow rate on plasma flow turbulization inside the torch channel is described. Also, measurements of voltage fluctuation due to motion of point of arc attachment are presented in the article. The mathematical model for the analysis of arc processes inside and outside of plasma torches is developed

Analysis of Electromagnetic Processes Inside the Arc Interrupting System of a High-current Circuit Breaker

Description of electromagnetic processes inside an arc interrupting system of high-current circuit breaker is presented in article. Non-stationary mathematical model of the circuit-breaker operation (short-circuit currents mode) is developed. The main regularities of the displacement of the electric arc inside an arc chute are established. The influence of the movable contact position on the conditions for the displacement of the electric arc is presented. Also, the influence of the arc chute material on the motion and interrupting of an electric arc (alternating and direct currents) is established

Assessment of Threats to the Security of the Cryptographic Authentication Mechanisms of the Monitor Devices of Vehicles

In accordance with the legislation on transport security, a number of vehicles must be equipped with on-Board control devices containing a cryptographic means of authentication, registration and storage of control data, including key information of the electronic signature. This paper presents a solution to the problem of justification of the adequacy of measures to counter known attacks and methods of discrediting the suggested cryptographic mechanisms and the corresponding protocol, drawn up in the form of a draft national standard and presented in the previous work of the authors devoted to study of its security properties. The solution presented is limited to the consideration of attacks divided into two large classes: passive and active attacks, including temporary attacks based on the study of the response time of one or more participants of the protocol. The analysis of the security threat model of the Protocol generating a common key with the authentication of subscribers intended for use in tachographs installed on vehicles shows that the protocol provides sufficient measures to counter known attacks. The found possible attacks are of a formal nature, not allowing the offender to obtain any additional information in order to discredit the protocol

Evaluation of the exposure to a ferroalloy plant for forest ecosystems by bioindication methods

Большинство металлургических предприятий оказывает негативное воздействие на лесные насаждения прилегающих к нему территорий. Одним из таких участков являются лесные насаждения вблизи п. Двуреченск Свердловской области, окружающие ферросплавный завод ПАО «КЗФ». Известно, что поллютанты металлургических предприятий оказывают влияние на все компоненты биогеоценоза, в частности на лесную растительность. Завод в последние десятилетия не работает на полную мощность и в значительной степени отвечает современным экологическим требованиям. Однако так было не всегда: очистные сооружения завода не обеспечивали задержание вредных выбросов, в результате чего накопление поллютантов на прилегающих территориях проводилось более полувека. Цель настоящей работы – оценка воздействия ферросплавного завода на лесные экосистемы зоны влияния, определение их состояния и выявление значимости индикаторов оценки. В работе проведены исследования по определению состояния лесных насаждений с использованием методов биоиндикации. Исследования проводились на временных пробных площадях (ВПП), заложенных на трансектах, которые располагаются в северном, восточном, южном и западном направлениях. На ВПП было определено санитарное состояние древостоев, средний возраст хвои сосны обыкновенной, произведен анализ на фитотоксичность проб почвы и талой снеговой воды. С целью оценки экологической ситуации от возможного воздействия завода определялось количество лишайников в лесном насаждении (метод лихеноиндикации). Оценка воздействия ферросплавного завода на лесные экосистемы выявила, что насаждения находятся в ослабленном состоянии. Достаточно четко прослеживается связь санитарного состояния древостоев с фитотоксичностью почв и талой снеговой воды, данными лихеноиндикации. В наибольшей степени влияние завода на состояние древостоя прослеживается в северной и восточной частях зоны.Most metallurgical enterprises have a negative impact on forest stands adjacent to it. One of these sites is forest plantations near the village of Dvurechensk, Sverdlovsk Region, surrounding the ferroalloy plant of PJSC «KZF». It is known that pollutants of metallurgical enterprises infl uence all components of the biogeocenosis, in particular, forest vegetation. Over the past decade, the plant has not been operating at full capacity and largely meets modern environmental requirements. However, this was not always the case — the treatment facilities of the plant did not provide for the containment of harmful emissions; as a result of the accumulation of pollutants in the adjacent territories, more than half a century was spent. The purpose of this work: to assess the impact of the ferroalloy plant on the forest ecosystems of the zone of infl uence, determine their condition and identify the signifi cance of the assessment indicators. The study conducted studies to determine the state of forest stands using bioindication methods. The studies were carried out on temporary trial plots (TTP) laid on transects located in the north, east, south and west. The TTP determined the sanitary condition of the stands, the average age of pine needles, and analyzed the phytotoxicity of soil and snowmelt samples. In order to assess the environmental situation from the possible impact of the plant, the number of lichens in the forest stands was determined (lichenoindication method). An assessment of the impact of the ferroalloy plant on forest ecosystems revealed that the stands are in a weakened state. The relationship between the sanitary state of the stands and the phytotoxicity of soils and melt snow water, lichenoindication, is quite clearly traced. The infl uence of the plant on the state of the stand is most pronounced in the northern and eastern parts of the zone

Analysis of Arc Processes in Multi-chamber Arrester for Lightning Protection at High-voltage Overhead Power Lines

Nowadays multi-chamber arresters are widely distributed as devices of lightning protection of overhead power lines. A mathematical modelling of processes in the discharge chamber of multichamber arrester is necessary to carry out in order to improve its breaking capacity. A three-dimensional mathematical transient model of thermal, gas-dynamic and electromagnetic processes taking place in the discharge chamber of multi-chamber arrester is presented in the article. Basic assumptions, model equations, a computational domain and the boundary conditions are described. Plasma turbulence is taken into account. The results of the calculation i.e. distributions of plasma temperature and overpressure in the discharge chamber at different time points are shown. The analysis of the results was carried out. It is shown that the presence of cavities in the electrodes design promotes electric arc extinction in the discharge chamber of multi-chamber arrester

ИСПОЛЬЗОВАНИЕ АНАТОМИЧЕСКОГО СТОЛА ДЛЯ ИЗУЧЕНИЯ ИНДИВИДУАЛЬНЫХ ОСОБЕННОСТЕЙ АРТЕРИАЛЬНОЙ СЕТИ ЛОКТЕВОГО СУСТАВА

The article represents a description of the individual features of the arterial network of the elbow joint and comparing results of the investigation with data of Russian and foreign anatomical schools of the USA, Canada, India and Great Britain. The investigation of the arterial network of the elbow joint of two male and two female dead bodies was implemented on the basis of the Anatomy Table. The screenshots was taken after extracting the arteries of this area. The graphic figures allowed to identify individual features of the arterial network of the elbow joint.Статья представляет собой описание индивидуальных особенностей артериальной сети локтевого сустава и сравнение полученного материала с данными российской и зарубежных анатомических школ США, Канады, Индии и Великобритании. Было проведено исследование артериальных сетей локтевого сустава у 4 тел (умерших 2 мужчин и 2 женщин) на основе использования анатомического стола. После выделения артерий указанной области были сделаны скриншоты. Полученные графические изображения позволили выявить индивидуальные особенности артериальной сети локтевого сустава

Investigation and Numerical Simulation of a High-Current AC Circuit Breaker

The article is devoted to the study of the high-current AC circuit breaker. The results of the study are presented for various configurations of the arc divider. The study includes methods of spectral diagnostics and high-speed camera shooting synchronized with the electrical characteristics of the circuit breaker (current, voltage) in time. The obtained results allow to determine the composition of the plasma and dynamics of changes in the composition of the discharge in time. Calculation of the plasma composition and properties is made according to the obtained data, which makes it possible to take into account the products of circuit breaker materials ablation in numerical simulation. Non-stationary two-dimensional mathematical model with a moving mesh is developed. The obtained results allow to correct and verify the developed mathematical model of the circuit breaker operation. The evaluation of the arc divider influence is presented in the article