Geostrophic tripolar vortices in a two-layer fluid : linear stability and nonlinear evolution of equilibria

We investigate equilibrium solutions for tripolar vortices in a two-layer quasi-geostrophic flow. Two of the vortices are like-signed and lie in one layer. An opposite-signed vortex lies in the other layer. The families of equilibria can be spanned by the distance (called separation) between the two like-signed vortices. Two equilibrium configurations are possible when the opposite-signed vortex lies between the two other vortices. In the first configuration (called ordinary roundabout), the opposite signed vortex is equidistant to the two other vortices. In the second configuration (eccentric roundabouts), the distances are unequal. We determine the equilibria numerically and describe their characteristics for various internal deformation radii. The two branches of equilibria can co-exist and intersect for small deformation radii. Then, the eccentric roundabouts are stable while unstable ordinary roundabouts can be found. Indeed, ordinary roundabouts exist at smaller separations than eccentric roundabouts do, thus inducing stronger vortex interactions. However, for larger deformation radii, eccentric roundabouts can also be unstable. Then, the two branches of equilibria do not cross. The branch of eccentric roundabouts only exists for large separations. Near the end of the branch of eccentric roundabouts (at the smallest separation), one of the like-signed vortices exhibits a sharp inner corner where instabilities can be triggered. Finally, we investigate the nonlinear evolution of a few selected cases of tripoles.PostprintPeer reviewe

Modeling the evolution of intrathermocline lenses in the Atlantic Ocean

The existence of a tongue of Mediterranean Water (MW) at the depths of 500–1500 m is a characteristic feature of the hydrological regime in the northeastern part of the Atlantic Ocean. Anticyclonic eddies filled with MW (meddies or lenses) are observed in this region. They are identified via their high temperature and salinity anomalies, which compensate in density, yielding nearly homogeneous meddy cores. The analysis of historical observations has showed that approximately 100 lenses can exist simultaneously in this part of the ocean. High concentration of large water volumes (\u3e4000 km3 each) can be found both in the region of their origin near the Iberian Peninsula and near the Azores Frontal Zone. The latter is precisely the region in which merging of eddies can occur to form larger lenses. The existence of long-living lenses at large distances from the region of their formation is an indirect indication of the fact that merging of lenses occurs (MESOPOLYGON lens, SM1 lens in the SEMAPHORE experiment, and a lens in the Sargasso Sea). Here, we analyze the results of model experiments on interaction between two anticyclonic eddies applying the contour dynamics method (CDM) to a three-layer ocean. In these experiments, the vertical distribution of layerwise density in the layers, the horizontal size of the eddies (assumed to be cylindrical structures), and their depth location correspond to the observed conditions in the Atlantic Ocean. We show that the evolution of intrathermocline eddies and the evolution of barotropic eddies differ significantly. We found the behavior of interacting eddies in the middle layer depends on the Froude number. We determined the critical distances between the lenses when their merger begins and the destruction\u27 criterion for the elliptical intrathermocline eddies

Interaction between a surface quasi-geostrophic buoyancy anomaly jet and internal vortices

This paper addresses the dynamical coupling of the ocean's surface and the ocean's interior. In particular, we investigate the dynamics of an oceanic surface jet, and its interaction with vortices at depth. The jet is induced by buoyancy (density) anomalies at the surface. We first focus on the jet alone. The linear stability indicates there are two modes of instability: the sinuous and the varicose modes. When a vortex in present below the jet, it interacts with it. The velocity field induced by the vortex perturbs the jet and triggers its destabilisation. The jet also influences the vortex by pushing it under a region of co-operative shear. Strong jets may also partially shear out the vortex. We also investigate the interaction between a surface jet and a vortex dipole in the interior. Again, strong jets may partially shear out the vortex structure. The jet also modifies the trajectory of the dipole. Dipoles travelling towards the jet at shallow incidence angles may be reflected by the jet. Vortices travelling at moderate incidence angles normally cross below the jet. This is related to the displacement of the two vortices of the dipole by the shear induced by the jet. Intense jets may also destabilise early and form streets of billows. These billows can pair with the vortices and separate the dipole.PostprintPeer reviewe

Investigation of Optical Properties and Radiation Stability of TiO2 Powders before and after Modification by Nanopowders of Various Oxides

The titanium dioxide powders are widely used as a pigment for coatings and paints, the important characteristics of which are reflectivity and stability to irradiation. The results of investigations of the optical properties and radiation stability of titanium dioxide powders before and after high-temperature modification with nanopowders are presented in this chapter. The diffuse reflection spectra of various titanium dioxide powders in the UV, visible, and near-IR ranges, and their change during irradiation by electrons with 30 keV energy and a different fluence in vacuum in situ were investigated: (1) TiO2 powders with particle size in the range 60–240 nm; (2) Microsized TiO2 powder (240 nm) modified by Al2O3, ZrO2, SiO2, TiO2, ZnO, MgO nanoparticles with grain size from 30 up to 60 nm; (3) Microsized TiO2 powder (260 nm) modified by SiO2 with the grain size of 12–14 nm at the temperature of 150, 400, and 800°C. The reduction in reflectivity in entire spectrum with decrease in grain sizes of TiO2 nanopowders was established. Nanopowder with the grain size of 80 nm possesses the highest stability to irradiation. It was shown that the average grain size and specific surface of introduced nanoparticles effect noticeably on the radiation stability increase of titanium dioxide powders modified with nanoparticles of various oxides. The micro-sized TiO2 powder heating at temperature of 800оС is the factor which positively influences on the radiation stability

Hetonic quartets in a two-layer quasi-geostrophic flow : V-states and stability

M.A.S. and X.C. were supported by RFBR/CNRS (PRC Grant No. 16-55-150001/1069). M.A.S. was supported also by RFBR (Grant No. 16-05-00121), RSF (Grant No. 14-50-00095, geophysical applications) and MESRF (Grant No. 14.W.03.31.0006, numerical simulation, vortex dynamics).We investigate families of finite core vortex quartets in mutual equilibrium in a two- layer quasi-geostrophic flow. The finite core solutions stem from known solutions for discrete (singular) vortex quartets. Two vortices lie in the top layer and two vortices lie in the bottom layer. Two vortices have a positive potential vorticity anomaly while the two others have negative potential vorticity anomaly. The vortex configurations are therefore related to the baroclinic dipoles known in the literature as hetons. Two main branches of solutions exist depending on the arrangement of the vortices: the translating zigzag-shaped hetonic quartets and the rotating zigzag- shaped hetonic quartets. By addressing their linear stability, we show that while the rotating quartets can be unstable over a large range of the parameter space, most translating quartets are stable. This has implications on the longevity of such vortex equilibria in the oceans.PostprintPeer reviewe

Психологічна залежність публічних службовців як фактор корупційної поведінки

The purpose of the article is to identify psychological aspects of preventing corruption in the professional activities of public servants by analyzing the main motives of systemic corruption behavior and socio-cultural aspects of their formation. It is revealed that research on the motives of corruption behavior is associated with several important factors: 1) the stereotypes of understanding of the corruption existing in the Ukrainian society; 2) social factors of corruption behavior - historical, economic, political, cultural, collective-psychological and individual psychological; 3) socio-cultural aspects of the formation of anticorruption consciousness.There are several motives of corruption behavior: game, social, monetary etc. This is due to the existence of the most common frames of mass consciousness, which are recorded in the Ukrainian society regarding the perception of corruption. The determining factors of the occurrence of corruption behavior in the professional activities of public servants are the psychological dependencies of the person, which leads to the use of the concept of psychological research.Corruptive behavior is defined as deviant one and causes the perception of the responsibilities of the public service as an opportunity to obtain satisfaction from the prospect of receiving unlawful benefits and privileges for violating official moral and ethical requirements (the formation of dependence). The types of psychological dependencies of public servants (on power, money, etc.) are distinguished. It is shown that a painful manifestation of such a person’s psychological dependency is kleptomania. In order to prevent corruption in the professional activities of public servants, it is proposed to apply scientifically substantiated psychological and diagnostic support, in particular special methods for determining the propensity for kleptomania and corruption behavior.Целью статьи является рассмотрение психологических аспектов предотвращения коррупции в профессиональной деятельности публичных служащих путем анализа основных мотивов системного коррупционного поведения и социокультурных аспектов их формирования. Выяснено, что исследование проблем мотивов коррупционного поведения связано с несколькими важными факторами: 1) существующие в украинском обществе стереотипы понимания коррупции; 2) социальные факторы коррупционного поведения – исторические, экономические, политические, культурные, коллективно-психологические и индивидуально-психологические; 3) социокультурные аспекты формирования антикоррупционного сознания. Выделены несколько мотивов коррупционного поведения: игровой, социальный, монетарный и тому подобное. Это обусловлено существованием нескольких распространенных фреймов массового сознания, которые фиксируются в украинском обществе относительно восприятия коррупции. Определяющими факторами возникновения коррупционного поведения в профессиональной деятельности публичных служащих являются психологические зависимости лица, что обусловливает применение концепции психологического исследования. Коррупционное поведение определяется как девиантное и обусловливает восприятие обязанностей публичной службы как возможность получения удовольствия от перспективы возможного получения неправомерной выгоды и льгот за нарушение официальных морально-этических требований (формирование зависимости). Выделены виды психологических зависимостей публичных служащих (от власти, денег и т.д.). Показано, что болезненным проявлением такой психологической зависимости человека является клептомания. Для предотвращения коррупции в профессиональной деятельности публичных служащих предложено применять научно обоснованное психолого-диагностическое сопровождение, в том числе специальные методики определения склонности к клептомании и коррупционному поведению.Метою статті є розгляд психологічних аспектів запобігання корупції у професійній діяльності публічних службовців шляхом аналізу основних мотивів системної корупційної поведінки та соціокультурних аспектів їх формування. З’ясовано, що дослідження проблем мотивів корупційної поведінки пов’язано з декількома важливими факторами: 1) існуючі в українському суспільстві стереотипи розуміння корупції; 2) соціальні чинники корупційної поведінки – історичні, економічні, політичні, культурні, колективно-психологічні та індивідуально-психологічні; 3) соціокультурні аспекти формування антикорупційної свідомості. Виокремлено кілька мотивів корупційної поведінки: ігровий, соціальний, монетарний тощо. Це обумовлено існуванням кількох найпоширеніших фреймів масової свідомості, які фіксуються в українському суспільстві щодо сприйняття корупції. Визначальними факторами виникнення корупційної поведінки у професійній діяльності публічних службовців є психологічні залежності особи, що обумовлює застосовування концепції психологічного дослідження. Корупційна поведінка визначається як девіантна та обумовлює сприйняття обов’язків публічної служби як можливість отримання задоволення від перспективи ймовірного отримання неправомірної вигоди та пільг за порушення офіційних морально-етичних вимог (формування залежності). Виділено види психологічних залежностей публічних службовців (від влади, грошей тощо). Показано, що хворобливим проявом такої психологічної залежності особи є клептоманія. Задля запобігання корупції у професійній діяльності публічних службовців запропоновано застосовувати науково обґрунтований психолого-діагностичний супровід, зокрема спеціальні методики визначення схильності до клептоманії та корупційної поведінки