Universality and self-similar behaviour of non-equilibrium systems with non-Fickian diffusion

Analytical approaches describing non-Fickian diffusion in complex systems are presented. The corresponding methods are applied to the study of statistical properties of pyramidal islands formation with interacting adsorbate at epitaxial growth. Using the generalized kinetic approach we consider universality, scaling dynamics and fractal properties of pyramidal islands growth. In the framework of generalized kinetics, we propose a theoretical model to examine the numerically obtained data for averaged islands size, the number of islands and the corresponding universal distribution over the island size.Comment: 10 pages, 6 figure

Three-body treatment of the penetration through the Coulomb field of a two-fragment nucleus

On the basis of the Faddeev integral equations method and the Watson- Feshbach concept of the effective (optical) interaction potential, the first fully consistent three-body approach to the description of the penetration of a charged particle through the Coulomb field of a two-particle bound complex (composed of one charged and one neutral particles) has been developed. A general formalism has been elaborated and on its basis, to a first approximation in the Sommerfeld parameter, the influence of the nuclear structure on the probability of the penetration of a charged particle (the muon, the pion, the kaon and the proton) through the Gamow barrier of a two-fragment nucleus (the deuteron and the two lightest lambda hypernuclei, lambda hypertriton and lambda hyperhelium-5, has been calculated and studied.Comment: LaTeX, 30 pages, 4 eps figure

Colored noise influence on the system evolution

We present a picture of phase transitions of the system with colored multiplicative noise. Considering the noise amplitude as the power-law dependence of the stochastic variable $x^a$ we show the way to phase transitions disorder-order and order-disorder. The governed equations for the order parameter and one-time correlator are obtained and investigated in details. The long-time asymptotes in the disordered and ordered domains on the phase portrait of the system are defined.Comment: 12 pages, 8 figures, LaTeX. Submitted to EPJ-

Global survey of star clusters in the Milky Way: III. 139 new open clusters at high Galactic latitudes

Context. An earlier analysis of the Milky Way Star Cluster (MWSC) catalogue revealed an apparent lack of old (t � 1 Gyr) open clusters in the solar neighbourhood (d � 1 kpc). Aims. To fill this gap we undertook a search for hitherto unknown star clusters, assuming that the missing old clusters reside at high Galactic latitudes | b | > 20°. Methods. We were looking for stellar density enhancements using a star count algorithm on the 2MASS point source catalogue. To increase the contrast between potential clusters and the field, we applied filters in colour-magnitude space according to typical colour-magnitude diagrams of nearby old open clusters. The subsequent comparison with lists of known objects allowed us to select thus far unknown cluster candidates. For verification they were processed with the standard pipeline used within the MWSC survey for computing cluster membership probabilities and for determining structural, kinematic, and astrophysical parameters. Results. In total we discovered 782 density enhancements, 524 of which were classified as real objects. Among them 139 are new open clusters with ages 8.3 < log (t [yr]) < 9.7, distances d< 3 kpc, and distances from the Galactic plane 0.3 <Z< 1 kpc. This new sample has increased the total number of known high latitude open clusters by about 150%. Nevertheless, we still observe a lack of older nearby clusters up to 1 kpc from the Sun. This volume is expected to still contain about 60 unknown clusters that probably escaped our detection algorithm, which fails to detect sparse overdensities with large angular size

Analysis of magnetic treatment of production fluid with high content of asphalt-resin-paraffin deposits

Purpose. Justification of magnetic field application in order to prevent formation of asphalt-resin-paraffin deposits (ARPD) in oil and gas equipment, and consider some current views on the state of ARPD problem in oilfield equipment and possible methods for its solution using magnetic treatment. Methods. Analysis and generalization of the research results of production fluid magnetic treatment using COMSOL Multiphysics software. Findings. The technology of magnetic fields application in prevention of asphalt-resin-paraffin deposits is introduced in the article. The obtained results of production fluid magnetic treatment make it possible to use it in oil wells equipped with pumping units, as well as in free flow production method or in wells operated by electric-centrifugal pump, and in oil pipelines. Originality. The use of high energy magnets based on rare earth materials can reduce asphalt-resin-paraffin deposits in oil equipment. Practical implications. The proposed magnetic treatment creates opportunities for field exploitation at the later stages of development which are characterized by a high content of asphaltenes, resins and paraffins. The results of production fluid magnetic treatment have proved the efficiency of this technology, which has doubled a turnaround time.Мета. Обґрунтувати використання магнітного поля для запобігання асфальтосмолистопарафінових відкладень на нафтогазовому обладнанні, а також розглянути сучасні погляди на стан проблеми асфальтосмолистопарафінових відкладень на нафтопромисловому обладнанні та можливі методи її вирішення за допомогою магнітної обробки. Методика. Аналіз та узагальнення результатів комплексу досліджень магнітної обробки свердловинної продукції за допомогою використання програми COMSOL Multiphysics. Результати. Запропоновано технологію використання магнітного поля для запобігання асфальтосмолистопарафінових відкладень. Отримані результати використання магнітної обробки свердловинної продукції дають можливість використовувати її у нафтопромисловій практиці як у свердловинах, які обладнанні штанговими свердловинними насосними установками, так і при експлуатації свердловин фонтанним способом або свердловин, що експлуатуються електровідцентровими насосами, а також на нафтопроводах. Наукова новизна. Використання високоенергетичних магнітів на основі рідкоземельних матеріалів, дозволяє зменшити асфальтосмолистопарафінові відклади на нафтовому обладнанні. Практична значимість. Запропонована магнітна обробка свердловинної продукції створює важливі передумови експлуатації родовищ, які знаходяться на пізніх стадії розробки та характеризуються великим вмістом асфальтенів, смол та парафінів. Результати проведення магнітної обробки свердловинної продукції довели ефективність використання даної обробки, що призвело до збільшення міжремонтного періоду у два рази.Цель. Обосновать использование магнитного поля для предотвращения асфальтосмолистопарафиновых отложений на нефтегазовом оборудовании, а также рассмотреть современные взгляды на состояние проблемы асфальтосмолистопарафинових отложений на нефтепромысловом оборудовании и возможные методы ее решения с помощью магнитной обработки. Методика. Анализ и обобщение результатов комплекса исследований магнитной обработки скважинной продукции с помощью использования программы COMSOL Multiphysics. Результаты. Предложена технология использования магнитного поля для предотвращения асфальтосмолистопарафиновых отложений. Полученные результаты использования магнитной обработки скважинной продукции, дают возможность использовать ее в нефтепромысловой практике как в скважинах, оборудованных штанговыми скважинными насосными установками, так и при эксплуатации скважин фонтанным способом или скважин, эксплуатируемых электроценторобежными насосами, а также на нефтепроводах. Научная новизна. Использование высокоэнергетических магнитов на основе редкоземельных материалов позволяет уменьшить асфальтосмолистопарафиновые отложения на нефтяном оборудовании. Практическая значимость. Предложенная магнитная обработка скважинной продукции создает важные предпосылки эксплуатации месторождений, которые находятся на поздней стадии разработки и характеризуются большим содержанием асфальтенов, смол и парафинов. Результаты проведения магнитной обработки скважинной продукции доказали эффективность использования данной обработки, что привело к увеличению межремонтного периода в два раза.The present study would have been impossible without support from Poltava National Technical Yuri Kondratyuk University administration. We express our sincere gratitude for the opportunity to conduct tests in modern Laboratory of Oil and Gas Technologies

Global survey of star clusters in the Milky Way I. The pipeline and fundamental parameters in the second quadrant

Aims: On the basis of the PPMXL star catalogue we performed a survey of star clusters in the second quadrant of the Milky Way. Methods: From the PPMXL catalogue of positions and proper motions we took the subset of stars with near-infrared photometry from 2MASS and added the remaining 2MASS stars without proper motions (called 2MAst, i.e. 2MASS with astrometry). We developed a data-processing pipeline including interactive human control of a standardised set of multi-dimensional diagrams to determine kinematic and photometric membership probabilities for stars in a cluster region. The pipeline simultaneously produced the astrophysical parameters of a cluster. From literature we compiled a target list of presently known open and globular clusters, cluster candidates, associations, and moving groups. From established member stars we derived spatial parameters (coordinates of centres and radii of the main morphological parts of clusters) and cluster kinematics (average proper motions and sometimes radial velocities). For distance, reddening, and age determination we used specific sets of theoretical isochrones. Tidal parameters were obtained by a fit of three-parameter King profiles to the observed density distributions of members. Results: We investigated all 871 objects in the 2nd Galactic quadrant, of which we successfully treated 642 open clusters, 2 globular clusters, and 8 stellar associations. The remaining 219 objects (24%) were recognised by us to be nonexistent clusters, duplicate entries, or clusters too faint for 2MAst. We found that our sample is complete in the 2nd quadrant up to a distance of 2 kpc, where the average surface density is 94 clusters per kpc$^{2}$. Compared with literature values we found good agreement in spatial and kinematic data, as well as for optical distances and reddening. Small, but systematic offsets were detected in the age determination.Comment: published in Astronomy and Astrophysics, 10 pages, 7 figures (plus 3 pages of appendices incl. 2 more figures), catalogues will be available at the CDS, all the machine-readable online data described in appendices A, B, and C are also available at: http://www.aip.de/People/rdscholz/kharchenko_etal_2012

Population analysis of open clusters: radii and mass segregation

Aims: Based on our well-determined sample of open clusters in the all-sky catalogue ASCC-2.5 we derive new linear sizes of some 600 clusters, and investigate the effect of mass segregation of stars in open clusters. Methods: Using statistical methods, we study the distribution of linear sizes as a function of spatial position and cluster age. We also examine statistically the distribution of stars of different masses within clusters as a function of the cluster age. Results: No significant dependence of the cluster size on location in the Galaxy is detected for younger clusters (< 200 Myr), whereas older clusters inside the solar orbit turned out to be, on average, smaller than outside. Also, small old clusters are preferentially found close to the Galactic plane, whereas larger ones more frequently live farther away from the plane and at larger Galactocentric distances. For clusters with (V - M_V) < 10.5, a clear dependence of the apparent radius on age has been detected: the cluster radii decrease by a factor of about 2 from an age of 10 Myr to an age of 1 Gyr. A detailed analysis shows that this observed effect can be explained by mass segregation and does not necessarily reflect a real decrease of cluster radii. We found evidence for the latter for the majority of clusters older than 30 Myr. Among the youngest clusters (between 5 and 30 Myr), there are some clusters with a significant grade of mass segregation, whereas some others show no segregation at all. At a cluster age between 50 and 100 Myrs, the distribution of stars of different masses becomes more regular over cluster area. In older clusters the evolution of the massive stars is the most prominent effect we observe.Comment: 14 pages, 12 figures, accepted for publication in Astronomy & Astrophysic