Application of TG/DSC Analysis under Variable Gas Phase Composition to Study Order-Disorder Transition in Nonstoichiometric Sr-Dy-Cobaltate

Методом термического анализа (ТГ/ДСК) в условиях постоянного и программированного состава газовой фазы изучено влияние скорости закалки на полноту перехода кубического разупорядоченного нестехиометрического перовскита (I) Sr(0.8)Dy(0.2)CoO(3-d) в тетрагональную модификацию (II) с упорядоченным расположением катионов Sr/Dy и анионных вакансий, а также взаимосвязь степени превращения I в II с количеством мобильного кислорода и его энергетическими характеристиками. Показано, что фазовое превращение протекает как фазовый переход первого рода, процесс образования структуры II контролируется кинетическими факторами, а использование скоростей охлаждения 3-99 К/мин позволяет получить образцы, формально соответствующие 98-30 % превращению I в II; при этом как количество подвижного кислорода, так и энтальпия его удаления из образца нелинейно зависят от полноты перехода I в IIFor the first time a method of TG/DSC analysis under constant and variable gas phase composition was applied to reveal interconnection between quenching ramp rates and degree of phase transformation of cubic nonstoichiometric disordered perovskite (I) Sr(0.8)Dy(0.2)CoO(3-d) to tetragonal structure (II) with ordered Sr/Dy cations and anion vacancies. It was shown that the transformation is a first order phase transition and the ordering process is kinetically controlled. Based on the experimental transition enthalpy it was found that a formal conversion degree of I to II was 98-30% under cooling ramp rates 3-99 K/min. Non-linear relationship between the completeness of I-to-II transformation and mobile oxygen characteristics (content and the enthalpy of O-removal) was demonstrate

SUBSTANTIATION AND DEVELOPMENT OF CREATION PROCESS OF MINE-SURVEYING GEODETIC AT MINING ENTERPRISES BY SATELLITE EQUIPMENT

There the comprehensive study which includes the works with simulators of networks, with real objects under mine conditions as well as the experimental industrial check of developed methods have been executed. The methods and which are new in the main, for creation of mine-surveying geodetic networks on the basis of satellite receiving equipment, which allow to create and to realize the up-dating of networks at the mining enterprises, thereof to rise the degree of control over the mining safety, have been developed. The results have been introduced at the mines of Leningradslanets Joint-Stock Company and at the Yerunakovo Deposit of KuzbassAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Study of a Gas Disturbance Mode Content Based on the Measurement of Atmospheric Parameters at the Heights of the Mesosphere and Lower Thermosphere

The main result of this work is the estimation of the entropy mode accompanying a wave disturbance, observed at the atmosphere heights range of 90–120 km. The study is the direct continuation and development of recent results on diagnosis of the acoustic wave with the separation on direction of propagation. The estimation of the entropy mode contribution relies upon the measurements of the three dynamic variables (the temperature, density, and vertical velocity perturbations) of the neutral atmosphere measured by the method of the resonant scattering of radio waves on the artificial periodic irregularities of the ionospheric plasma. The measurement of the atmosphere dynamic parameters was carried out on the SURA heating facility. The mathematical foundation of the mode separation algorithm is based on the dynamic projection operators technique. The operators are constructed via the eigenvectors of the coordinate evolution operator of the transformed system of balance equations of the hydro-thermodynamics

Dismantling and decontamination of large-sized radiation-contaminated equipment during Research Building B decommissioning at the Bochvar Institute site

The article presents the results of work on dismantling the large installation equipment of Research Building B at the Bochvar High-technology Research Institute of Inorganic Materials (Bochvar Institute). The works were carried out as part of Building B preparation for decommissioning. The purpose of dismantling the large-sized capacitive equipment was to reconstruct the large installation site for managing radioactive waste generated during Building B decommissioning. The works on decommissioning a radioactively contaminated building within a densely populated district of megalopolis were carried out for the first time. The characteristics of the large-sized capacitive equipment are presented. Radioactive contamination of the capacitive equipment is determined by long-lived a-emitting isotopes: 235U, 238U, 239Pu. The sequence of works on dismantling the radiation-contaminated capacitive equipment includes preparatory work, dismantling the tank piping, localizing radioactive contamination of the external surface of the equipment as well as dismantling and moving it into a transport container. Dismantling and decontamination of the large-sized capacitive equipment was carried out by the Bochvar Institute Decommissioning Department. The following tools were used during the works: (1) a mobile foam decontamination facility to perform decontamination works and (2) a mobile high pressure facility to apply localizing and decontaminating film coatings. The tanks were dismantled by means of low-spark tools, i.e., reciprocating saws. Crane runways were made in order to move the dismantled equipment into transport containers: the movement was carried out with the help of a winch. The main results of dismantling and decontaminating the radioactively contaminated tanks are the dismantling of four units of long-length column-type equipment with heights from 4.2 to 6.4 m and 26 units of capacitive equipment (maximum capacity = 8 m3) as well as decontamination of the internal surfaces of radiation-contaminated equipment (decontamination factor = 25–70). As a result, the activity of the accumulated radioactive waste was reduced (the RW class was changed from 3 to 4). The main conclusion regarding the managment of large-sized radiation-contaminated tanks during Building B decommissioning is as follows: the works were organized and carried out at a high technical level, using modern decontamination and dismantling equipment and modern methods to ensure work safety at the Bochvar Institute site in the city of Moscow

Effect of Oxygen Nonstoichiometry on Electrical Conductivity and Thermopower of Gd0.2Sr0.8FeO3−δ Ferrite Samples

The behavior of the resistivity and thermopower of the Gd0.2Sr0.8FeO3−δ ferrite samples with a perovskite structure and the sample stability in an inert gas atmosphere in the temperature range of 300–800 K have been examined. It has been established that, in the investigated temperature range, the thermoelectric properties in the heating‒cooling mode are stabilized at δ ≥ 0.21. It is shown that the temperature dependencies of the resistivity obtained at different δ values obey the activation law up to the temperatures corresponding to the intense oxygen removal from a sample. The semiconductor‒semiconductor electronic transitions accompanied by a decrease in the activation energy have been observed with increasing temperature. It is demonstrated that the maximum thermoelectric power factor of 0.1 µW/(cm·K2) corresponds to a temperature of T = 800 K

Creación de una región p+ en el CdTe, mediante el depósito de Te por el método CSVT tradicional y modificado

The behavior of electrical resistance and thermopower of the Gd 0.2Sr0.8FeO3-δ ferrite samples with the perovskite structure and their stability in the inert gas atmosphere in the temperature range of 300–800 K have been investigated. It has been established that, in the temperature range of interest, the thermoelectric properties in the heating‒cooling mode stabilize at δ ≥ 0.21. Temperature dependences of the electrical resistance obtained at different δ values have been shown to obey the activation law up to the temperatures of active removal of oxygen from the sample. As the temperature increases, the semiconductor‒semiconductor electronic transitions with the activation energy lowering have been observed. The maximum thermoelectric power factor of 0.1 µW/(cm • K2) has been obtained at Т = 800 K

Helium Permeability Studies of Fly Ash Cenospheres

В работе представлен метод исследования проницаемости полых микросферических мембран на примере ценосфер энергетических зол (ЦЭЗ). Приведено описание экспериментальной вакуумной установки для исследования процессов диффузии индивидуальных газов в ценосферы в статических условиях и математический аппарат для расчёта количественных характеристик процесса. В интервале температур 300 - 500 °С определена гелиевая проницаемость узкой фракции ценосфер, выделенной из концентрата ЦЭЗ Московской ТЭЦ-22, определены величины удельной проницаемости 3,5∙10-12 - 3,5∙10-11 моль/(с·г∙Па); объёма, доступного для гелия (2,13 0,06)∙10-6 м3/г, и энергии активации процесса поглощения (34±3) кДж/моль. На примере смеси гелия с воздухом в хроматографическом режиме впервые экспериментально продемонстрирована возможность разделения гелийсодержащих смесей с использованием ЦЭЗ.This work presents the methods of permeability studies of hollow microspheric membranes (cenospheres of fly ashes). A description of the experimental vacuum set-up designed to study the process of diffusion of individual gases into cenospheres in static conditions is provided, as well as the mathematical method to calculate the quantitative characteristics of the said process. The helium permeability of the narrow fraction of cenospheres isolated from fly ash concentrate of Moscow power station was measured. The specific permeability was shown to be equal to the values of 3.5·10-12 - 3.5·10-11 mol/ (s·g·Pa) in the temperature range 300 - 500°C. The values of the volume available to helium and activation energy of Не sorption were found (2.13±0.06)·10-6 m3/g and 34±3 kJ/mol, respectively. It was shown for the fist time, that helium can be successfully separated from air using cenospheres in chromatographic mode

CARS and Fluorescent study of ignition of H

The research is devoted to gas mixtures ignition by UV laser radiation. The dissociation of O2 molecules by a pulse of excimer ArF laser radiation at 193-nm wavelength with formation of the chemically active oxygen atoms initiating chain reactions which cause ignition of H2/O2 mixture was employed. The experimental test bench was created with CARS and fluorescent techniques for experimental investigation of some peculiarities of mixture ignition and combustion caused by such photo-dissociation, at conditions typical for combustion chamber. Two-dimensional numerical modeling of combustion process in model combustion chamber, based on kinetic mechanism of H2 oxidation including atom O(1P) and radicals OH(A2Σ+), was performed

CARS and Fluorescent study of ignition of H2/O2 mixtures upon photodissociation of O2 molecular

The research is devoted to gas mixtures ignition by UV laser radiation. The dissociation of O2 molecules by a pulse of excimer ArF laser radiation at 193-nm wavelength with formation of the chemically active oxygen atoms initiating chain reactions which cause ignition of H2/O2 mixture was employed. The experimental test bench was created with CARS and fluorescent techniques for experimental investigation of some peculiarities of mixture ignition and combustion caused by such photo-dissociation, at conditions typical for combustion chamber. Two-dimensional numerical modeling of combustion process in model combustion chamber, based on kinetic mechanism of H2 oxidation including atom O(1P) and radicals OH(A2Σ+), was performed