Magnetic Characterization of Fischer-Tropsch Catalysts

INGENIERIE+JDAInternational audienceThis paper reviews recent developments in the application of magnetic methods for investigation of Fischer-Tropsch catalysts involving cobalt, iron and nickel. Magnetic characterization provides valuable information about catalyst reduction, sizes of ferromagnetic nanoparticles, chemisorption on ferromagnetics and topochemical reactions which occur with the catalysts during the genesis of the active phase and in the conditions of Fischer-Tropsch synthesis. The capabilities and challenges of the magnetic methods are discussed.Cet article passe en revue les développements récents dans le domaine de la caractérisation des catalyseurs Fischer-Tropsch à base de cobalt, de fer et de nickel par la méthode magnétique. La caractérisation magnétique fournit des informations précieuses sur la réduction du catalyseur, la taille des nanoparticules ferromagnétiques, la chimisorption, ainsi que sur les réactions topo chimiques qui se produisent avec les catalyseurs au cours de la genèse de la phase active et dans des conditions réactionnelles. Les possibilités et les limites de la méthode magnétique sont examinée

Применение двухточечного метода калибровки для тепловизионных матриц фирмы ULIS

The objective of this work is research and modification of the two-point calibration method for long wavelength infrared uncooled microbolometer ULIS' matrices. The ultimate goal is to obtain better thermal image for the end-user, where quality criteria are such characteristics as a visual contrast, ability to distinguish fine details, and noisy image as less as possible.In considering the most common calibration algorithm of infrared uncooled microbolometer matrices we used the study results of other authors in which results and comparative analyses of the most effective algorithms were provided. Based on these investigations, to make modification have been chosen quite effective and at the same time simple computationally two-point calibration method, which is sufficient for most tasks entrusted to thermal imager.Modification of the two-point calibration method involves introducing variable reference voltages, which nominal values depend on the temperature range of the matrix. In the original version of the algorithm a reference voltage was selected for the whole range of possible temperatures of the matrix, which did not guarantee the required level of minimum sensitivity. The results of the algorithm embedded in a real device and experimental results proved the effectiveness of this modification.The known specialized literature describing calibration methods for long wavelength infrared uncooled microbolometer matrices do not mention this type of modification.The method described in this publication can be applied to various practical implementations of the thermal imagers without cover and algorithms, which can improve image quality.The article shows advisability and effectiveness of using the modified two-point calibration method for design of thermal imagers without cover with a wide range of operating temperatures.Приводятся краткий обзор наиболее распространённых на текущее время методов калибровки (двухточечная и многоточечная) и вариант модифицированного алгоритма двухточечной калибровки приборов бесшторкового типа, построенных на основе неохлаждаемых микроболометрических матриц фирмы ULIS (Long Wavelength Infrared uncooled microbolometer). В статье отражены описание процедуры калибровки, получения результатов, кратко описан интерфейс программы, реализованной на языке С и используемой в данной работе, а так же сам прибор, используемый для апробации модифицированного алгоритма. Результаты данной работы могут быть интересны при практической реализации бесшторковых тепловизоров и алгоритмов улучшения качества изображения

Search for the decay KL0→3γK_L^0 \rightarrow 3\gamma

We performed a search for the decay $K_L^0 \rightarrow 3\gamma$ with the E391a detector at KEK. In the data accumulated in 2005, no event was observed in the signal region. Based on the assumption of $K_L^0 \rightarrow 3\gamma$ proceeding via parity-violation, we obtained the single event sensitivity to be $(3.23\pm0.14)\times10^{-8}$, and set an upper limit on the branching ratio to be $7.4\times10^{-8}$ at the 90% confidence level. This is a factor of 3.2 improvement compared to the previous results. The results of $K_L^0 \rightarrow 3\gamma$ proceeding via parity-conservation were also presented in this paper

Совершенствование конструкции ремонтных плавучих доков

Рашковский, А. С. Совершенствование конструкции ремонтных плавучих доков = Improvement of the floating repair dock structure / А. С. Рашковский, А. В. Щедролосев, В. Н. Перов // Зб. наук. пр. НУК. – Миколаїв : НУК, 2016. – № 1 (463). – С. 11–18.Анотація. В статті розглянуто варіанти розкріплення ремонтного плавучого доку за допомогою палів, які закріплені на башті доку чи в спеціальному котловані біля пірсу. Для визначення розмірів конструктивних елементів пристрою для розкріплення доку до пірсу розглянуто діючі навантаження, розроблено розрахункові схеми та наведено розрахунок міцності палу та серги.Abstract The most popular modern type of the repair dock is a large composite floating dock with the large lifting capacity, consisting of the reinforced concrete pontoon and two solid steel towers. In order to serve the ship, a floating dock is submerged to a certain depth in the water area of the enterprise into a specially dug pit. In regular practice, floating repair docks are unfastened in the area of their operation (diving pit) with the use of a special anchor system consisting of anchors, chains and underlying arrays. At a number of shipyards, a special underwater pit used to submerse a floating dock at the receiving and launching of the vessel is made close to the pier in order not to build it in the waters. It saves the cost and time of moving the dock to the pits and back to the pier. The article describes the options for unfastening a floating repair dock using bollards fixed on the tower of the dock or in the pit near the pier. To determine the size of the structural elements of a device for the dock unfastening to the pier, operating loads are considered, calculation schemes are designed and the strength of the bollard and slip-rope is calculated.Аннотация. В статье рассмотрены варианты раскрепления ремонтного плавучего дока с помощью палов, закрепляемых на башне дока или в специальном котловане возле пирса. Для определения размеров конструктивных элементов устройства для раскрепления дока к пирсу рассмотрены действующие нагрузки, разработаны расчетные схемы и произведен расчет прочности пала и серьги

Experimental study of the decay KL0→π0ννˉK_L^0\to\pi^0\nu\bar{\nu}

The first dedicated search for the rare neutral-kaon decay $K_L^0\to\pi^0\nu\bar{\nu}$ has been carried out in the E391a experiment at the KEK 12-GeV proton synchrotron. The final upper limit of 2.6 $\times 10^{-8}$ at the 90% confidence level was set on the branching ratio for the decay.Comment: 23 pages, 27 figures, accepted for publication as a regular article in Physical Review

Multiferroic Coupling of Ferromagnetic and Ferroelectric Particles through Elastic Polymers

Multiferroics are materials that electrically polarize when subjected to a magnetic field and magnetize under the action of an electric field. In composites, the multiferroic effect is achieved by mixing of ferromagnetic (FM) and ferroelectric (FE) particles. The FM particles are prone to magnetostriction (field-induced deformation), whereas the FE particles display piezoelectricity (electrically polarize under mechanical stress). In solid composites, where the FM and FE grains are in tight contact, the combination of these effects directly leads to multiferroic behavior. In the present work, we considered the FM/FE composites with soft polymer bases, where the particles of alternative kinds are remote from one another. In these systems, the multiferroic coupling is different and more complicated in comparison with the solid ones as it is essentially mediated by an electromagnetically neutral matrix. When either of the fields, magnetic or electric, acts on the ‘akin’ particles (FM or FE) it causes their displacement and by that perturbs the particle elastic environments. The induced mechanical stresses spread over the matrix and inevitably affect the particles of an alternative kind. Therefore, magnetization causes an electric response (due to the piezoeffect in FE) whereas electric polarization might entail a magnetic response (due to the magnetostriction effect in FM). A numerical model accounting for the multiferroic behavior of a polymer composite of the above-described type is proposed and confirmed experimentally on a polymer-based dispersion of iron and lead zirconate micron-size particles. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The reported study was funded by the Russian Scientific Foundation according to research project No. 21-72-30032 (experimental investigation and analysis); authors Makarova L.A. and Isaev D.A. acknowledge the President of the Russian Federation Grant Number MK-716.2020.2 (simulation results). Authors Isaenko M.B. and Perov N.S. acknowledge partial support from Lomonosov Moscow State University Program of Development