Oil and gas bearing capacity of Paleocene carbonate formations of the southern oil and gas bearing region

According to the results of exploration work the industrial gas content of Palaeocene formation in the southern oil and gas bearing region is found within the western regions of plain Crimea and the northwest shelf of the Black Sea. Favorable conditions for non-anticlinal traps were also found associated primarily with cutting-in of collectors. 64.5 million toe in the off-shore and 21.5 million toe of hydrocarbons on land remain unexplored

Possibilities of using stability lobe diagram for stability prediction of high speed milling of thinwalled details

Високошвидкісне фрезерування – продуктивний і ефективний процес, який стає все більш популярним в наш час. Особливо при фрезеруванні тонкостінних елементів деталей з аеродинамічними поверхнями. На виробництві часто стикаються з проблемою отримання тонкостінних деталей пов’язаною з виникненням вібрацій і теорія побудови діаграм вібросталості в більшості випадків не дозволяє уникнути цієї проблеми шляхом вибору відповідних умов різання. На практиці режими обробки з мінімальними вібраціями для фрезерування тонкостінних деталей визначаються, як правило, експериментальним шляхом. В даній роботі автори представляють основні відмінності кінцевого фрезерування тонкостінних деталей від класичного кінцевого фрезерування, показують особливості процесу фрезерування тонкостінних деталей і аспекти, які впливають на якість обробленої поверхні. Метою даної роботи є підтвердження, що при високій швидкості кінцевого фрезерування тонкостінних деталей причиною несталості процесу різання є не тільки виникнення регенеративних коливань. Проведена порівняльна оцінка вібросталості, отриманої за допомогою розрахункового методу та побудованою за експериментальними даними.High-speed milling is a cost and time effective process, which becomes more popular nowadays. It is especially available at milling of thin-walled structures of airfoil components. Manufacturer often faced with problem of producing thin-walled parts due to vibration and stability lobes theory in a lot of cases does not allow to avoid this problem by choosing the appropriate cutting conditions. In practice cutting condition for milling of thin walled detail is usually obtained by experimental way. In this paper authors present main differences of thin-walled end milling from classical end milling and show features of thin-walled end milling process and aspects, which effect on quality of surface finish. The aim of the paper is to validate that at high speed thin-walled end milling not only chatter is the reason of unstable cutting condition. Evaluation of stability, obtained by experimental tests, was compared with stability lobe diagram.Высокоскоростное фрезерование – производительный и эффективный процесс, который становится все более популярным в наше время. Особенно при фрезеровании тонкостенных элементов деталей с аэродинамическими поверхностями. На производстве часто сталкиваются с проблемой получения тонкостенных деталей связанной с возникновением вибраций. Теория построения диаграмм виброустойчивости в большинстве случаев не позволяет устранить эту проблему путем выбора соответствующих условий резания. На практике режимы обработки с минимальными вибрациями для фрезерования тонкостенных деталей определяются, как правило, экспериментальным путем. В данной работе авторы представляют основные отличия концевого фрезерования тонкостенных деталей от классического концевого фрезерования, показывают особенности процесса фрезерования тонкостенных деталей и аспекты, которые влияют на качество обработанной поверхности. Целью данной работы является подтверждение гипотезы, что при высокоскоростном концевом фрезеровании тонкостенных деталей причиной неустойчивости процесса резания является не только возникновение регенеративных колебаний. Проведена сравнительная оценка виброустойчивости, полученная с помощью расчетного метода и построенной по экспериментальным данным

Magnetic Anisotropy of Ultra-small Nanocrystals of CoFe2O4

Ferrimagnetic nanoparticles of CoFe2O4 with dimensions of 4-16 nm were synthesized by pyrolysis of a mixture of acetylacetonates of iron and cobalt. In the temperature range 300-500 K investigated field dependence of magnetization up o 18 kOe. Found a significant contribution of "surface" anisotropy to the effective anisotropy of the nanoparticles. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3536

PSYCHOLOGICAL PECULIARITIES OF PROFESSIONAL RESPONSIBILITY OF FUTURE SPECIALISTS OF THE CIVIL DEFENCE SERVICE

The essence of the concept of “responsibility” and “professional responsibility of a rescuer” is revealed in the article; the psychological foundations of the development of responsible behavior are analyzed; the main ways and means that ensure the success of the process of the responsibility formation, the main pedagogical conditions for improving educational activities and the formation of responsibility among the cadets are presented.The essence of the concept of “responsibility” and “professional responsibility of a rescuer” is revealed in the article; the psychological foundations of the development of responsible behavior are analyzed; the main ways and means that ensure the success of the process of the responsibility formation, the main pedagogical conditions for improving educational activities and the formation of responsibility among the cadets are presented

The ion-acoustic instability in the pre-flare plasma near the loop footpoints at solar active regions

The necessary physical conditions for development of the ion-acoustic instability in the chromospheric part of a flaring loop current circuit are investigated. Two possible scenarios have been studied. First, we consider that pre-flare loop plasma with the large-scale sub-Dreicer electric field has a classical Coulomb conductivity and, second, when anomalous resistance appears due to saturation of Bernstein turbulence. The Fontenla-Avrett-Loeser (FAL) model of the solar atmosphere was used to describe the pre-flare plasma. We have shown that investigated instability can grow and develop either in the presence of the Coulomb conductivity or saturated Bernstein turbulence. We demonstrate that in the case of small-scale instability, the threshold value for the degree of nonisothermality is high and, therefore, cannot be reached by inclusion of the ordinary Joule heating. The ion-acoustic instability can develop at the pre-flare loop footpoints provided the electrons are more than 10 times hotter than the ions there. © Author(s) 2013

Generation of low-frequency kinetic waves at the footpoints of pre-flare coronal loops

In this study we discuss the excitation of low-frequency plasma waves in the lower-middle chromosphere region of loop footpoints for the case when the plasma can be considered to be in a pre-flare state. It is shown that among the well-known semi-empirical models of the solar atmosphere, only the VAL (F) model together with a particular set of basic plasma parameters and amplitudes of the electric and magnetic fields supports generation of low-frequency wave instability. Our results show that it is possible to predict the onset of the flare process in the active region by using the interaction of kinetic Alfvén and kinetic ion-acoustic waves, which are solutions of the derived dispersion equation. The VAL (F) model allows situations when the main source of the aforementioned instability can be a sub-Dreicer electric field and drift plasma movements due to presence of spatial inhomogeneities. We also show that the generation of kinetic Alfvén and kinetic ion-acoustic waves can occur both, in plasma with a purely Coulomb conductivity and in the presence of small-scale Bernstein turbulence. The excitation of the small amplitude kinetic waves due to the development of low threshold instability in plasma with relatively low values of the magnetic field strength is also discussed

Magnetic Anisotropy of Ultra-small Nanocrystals of CoFe2O4

Ferrimagnetic nanoparticles of CoFe2O4 with dimensions of 4-16 nm were synthesized by pyrolysis of a mixture of acetylacetonates of iron and cobalt. In the temperature range 300-500 K investigated field dependence of magnetization up o 18 kOe. Found a significant contribution of "surface" anisotropy to the effective anisotropy of the nanoparticles. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3536

Generation of localised vertical streams in unstable stratified atmosphere

A new model of axially symmetric concentrated vortex generation was developed herein. In this work, the solution of a nonlinear equation for internal gravity waves in an unstable stratified atmosphere was obtained and analysed in the framework of ideal hydrodynamics. The related expressions for the velocities in the inner and outer regions of the vortex were described by Bessel functions and modified zeroth-order Bessel functions. The proposed new nonlinear analytical model allows the study of the structure and dynamics of vortices in the radial region. The formation of jets (i.e., structures elongated in the vertical direction with finite components of the poloidal (radial and vertical) velocities that grow exponentially in time in an unstable stratified atmosphere) was also analysed. The characteristic growth time was determined by the inverse growth rate of instability. It is shown that a seed vertical vorticity component may be responsible for the formation of vortices with a finite azimuthal velocity

Enhanced Piezoelectricity of Electrospun Polyvinylidene Fluoride Fibers for Energy Harvesting

Piezoelectric polymers are promising energy materials for wearable and implantable applications for replacing bulky batteries in small and flexible electronics. Therefore, many research studies are focused on understanding the behavior of polymers at a molecular level and designing new polymer-based generators using polyvinylidene fluoride (PVDF). In this work, we investigated the influence of voltage polarity and ambient relative humidity in electrospinning of PVDF for energy-harvesting applications. A multitechnique approach combining microscopy and spectroscopy was used to study the content of the β-phase and piezoelectric properties of PVDF fibers. We shed new light on β-phase crystallization in electrospun PVDF and showed the enhanced piezoelectric response of the PVDF fiber-based generator produced with the negative voltage polarity at a relative humidity of 60%. Above all, we proved that not only crystallinity but also surface chemistry is crucial for improving piezoelectric performance in PVDF fibers. Controlling relative humidity and voltage polarity increased the d33 piezoelectric coefficient for PVDF fibers by more than three times and allowed us to generate a power density of 0.6 μW·cm-2 from PVDF membranes. This study showed that the electrospinning technique can be used as a single-step process for obtaining a vast spectrum of PVDF fibers exhibiting different physicochemical properties with β-phase crystallinity reaching up to 74%. The humidity and voltage polarity are critical factors in respect of chemistry of the material on piezoelectricity of PVDF fibers, which establishes a novel route to engineer materials for energy-harvesting and sensing applications