Geometry and violent events in turbulent pair dispersion

The statistics of Lagrangian pair dispersion in a homogeneous isotropic flow is investigated by means of direct numerical simulations. The focus is on deviations from Richardson eddy-diffusivity model and in particular on the strong fluctuations experienced by tracers. Evidence is obtained that the distribution of distances attains an almost self-similar regime characterized by a very weak intermittency. The timescale of convergence to this behavior is found to be given by the kinetic energy dissipation time measured at the scale of the initial separation. Conversely the velocity differences between tracers are displaying a strongly anomalous behavior whose scaling properties are very close to that of Lagrangian structure functions. These violent fluctuations are interpreted geometrically and are shown to be responsible for a long-term memory of the initial separation. Despite this strong intermittency, it is found that the mixed moment defined by the ratio between the cube of the longitudinal velocity difference and the distance attains a statistically stationary regime on very short timescales. These results are brought together to address the question of violent events in the distribution of distances. It is found that distances much larger than the average are reached by pairs that have always separated faster since the initial time. They contribute a stretched exponential behavior in the tail of the inter-tracer distance probability distribution. The tail approaches a pure exponential at large times, contradicting Richardson diffusive approach. At the same time, the distance distribution displays a time-dependent power-law behavior at very small values, which is interpreted in terms of fractal geometry. It is argued and demonstrated numerically that the exponent converges to one at large time, again in conflict with Richardson's distribution.Comment: 21 page

Timescales of Turbulent Relative Dispersion

Tracers in a turbulent flow separate according to the celebrated $t^{3/2}$ Richardson--Obukhov law, which is usually explained by a scale-dependent effective diffusivity. Here, supported by state-of-the-art numerics, we revisit this argument. The Lagrangian correlation time of velocity differences is found to increase too quickly for validating this approach, but acceleration differences decorrelate on dissipative timescales. This results in an asymptotic diffusion $\propto t^{1/2}$ of velocity differences, so that the long-time behavior of distances is that of the integral of Brownian motion. The time of convergence to this regime is shown to be that of deviations from Batchelor's initial ballistic regime, given by a scale-dependent energy dissipation time rather than the usual turnover time. It is finally argued that the fluid flow intermittency should not affect this long-time behavior of relativeComment: 4 pages, 3 figure

Turbulent cross-field transport of non-thermal electrons in coronal loops: theory and observations

<p><b>Context:</b> A fundamental problem in astrophysics is the interaction between magnetic turbulence and charged particles. It is now possible to use Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations of hard X-rays (HXR) emitted by electrons to identify the presence of turbulence and to estimate the magnitude of the magnetic field line diffusion coefficient at least in dense coronal flaring loops.</p> <p><b>Aims:</b> We discuss the various possible regimes of cross-field transport of non-thermal electrons resulting from broadband magnetic turbulence in coronal loops. The importance of the Kubo number K as a governing parameter is emphasized and results applicable in both the large and small Kubo number limits are collected.</p> <p><b>Methods:</b> Generic models, based on concepts and insights developed in the statistical theory of transport, are applied to the coronal loops and to the interpretation of hard X-ray imaging data in solar flares. The role of trapping effects, which become important in the non-linear regime of transport, is taken into account in the interpretation of the data.</p> <p><b>Results:</b> For this flaring solar loop, we constrain the ranges of parallel and perpendicular correlation lengths of turbulent magnetic fields and possible Kubo numbers. We show that a substantial amount of magnetic fluctuations with energy ~1% (or more) of the background field can be inferred from the measurements of the magnetic diffusion coefficient inside thick-target coronal loops.</p&gt

Kolmogorov-Sinai entropy in field line diffusion by anisotropic magnetic turbulence

The Kolmogorov-Sinai (KS) entropy in turbulent diffusion of magnetic field lines is analyzed on the basis of a numerical simulation model and theoretical investigations. In the parameter range of strongly anisotropic magnetic turbulence the KS entropy is shown to deviate considerably from the earlier predicted scaling relations [Rev. Mod. Phys. {\bf 64}, 961 (1992)]. In particular, a slowing down logarithmic behavior versus the so-called Kubo number $R\gg 1$ ($R = (\delta B / B_0) (\xi_\| / \xi_\bot)$, where $\delta B / B_0$ is the ratio of the rms magnetic fluctuation field to the magnetic field strength, and $\xi_\bot$ and $\xi_\|$ are the correlation lengths in respective dimensions) is found instead of a power-law dependence. These discrepancies are explained from general principles of Hamiltonian dynamics. We discuss the implication of Hamiltonian properties in governing the paradigmatic "percolation" transport, characterized by $R\to\infty$, associating it with the concept of pseudochaos (random non-chaotic dynamics with zero Lyapunov exponents). Applications of this study pertain to both fusion and astrophysical plasma and by mathematical analogy to problems outside the plasma physics. This research article is dedicated to the memory of Professor George M. ZaslavskyComment: 15 pages, 2 figures. Accepted for publication on Plasma Physics and Controlled Fusio

An examination of the relationship between adolescenst's perceived parental psychological control, early maladaptive schemas and adjustment problems

Eğitim Bilimleri Enstitüsü, Aile Danışmanlığı Ana Bilim Dalı, Aile Danışmanlığı Bilim DalıAilelerin geçirdiği en önemli evrelerden biri çocuklarının ergenlik dönemidir. Ergenlik dönemi aileler için olduğu kadar ergenler içinde zorlu bir dönem olmakta ve ergenler bu dönemde fazlaca uyum sorunları yaşamaktadır. Ergen bireyin özerklik çabasına karşın ebeveynlerin kontrol çabasının bulunduğu bu dönemde ebeveynlerin uyguladığı kontrol oldukça önemlidir. Bu çalışmada ebeveynlerin uyguladıkları psikolojik kontrol, gelişimin erken dönemlerinde başlayan, çocukluk ya da ergenlik döneminde gelişim gösteren, yaşam doyumu ve uyumunu etkileyen bilişsel örüntüler olarak tanımlanan 'erken dönem uyumsuz şemalar ve ergenlerin uyum sorunları arasındaki ilişki incelenmiştir. Çalışmanın amacı, aileden algılanan psikolojik kontrol ve erken dönem uyumsuz şemaların, ergenlerin uyum sorunlarını anlamlı bir biçimde yordayıp yordamadığının incelenmesidir. Araştırmada, ayrıca ebeveyn psikolojik kontrolünün, erken dönem uyumsuz şemalarının ve uyum sorunlarının bazı değişkenlerle (ergen cinsiyeti, ebeveyn eğitim düzeyi, ebeveyn cinsiyeti) ilişkilerinin ortaya konması amaçlanmıştır. Araştırmanın evrenini Türkiye de yaşayan tüm ergenler oluştururken hedef örneklemi ise Çanakkale ili merkez ilçede lise eğitimini sürdüren 9 ve 10. sınıfta okuyan ergenler oluşturmaktadır. Örneklem gurubu, 2018- 2019 eğitim öğretim yılında M.E.B bağlı Çanakkale ili merkez ilçelerdeki liselerde eğitimini sürdüren ergenlerden oluşmuştur ve örneklem sayısı 462'dir. Araştırmada ergenlere Kişisel Bilgi Formu, Psikolojik Kontrol Ölçeği, 10-16 Yas? Çocuk ve Ergenler için Erken Dönem Uyumsuz Şema Ölçekler Takımı (ÇEŞÖT) ve Reynolds Ergenler İçin Uyum Tarama Envanteri (REUTE) uygulanmıştır. Araştırmadan elde edilen veriler Spss 20.0 paket programıyla analiz edilmiş, cinsiyet iv ve diğer değişkenler açısından farklılaşmalar için t Testi ve One-way Anova, ebeveyn psikolojik kontrolü, erken dönem uyumsuz şemalar ve uyum sorunları değişkenlerinin ilişkilerinin analizi için Pearson Korelasyon analizi ve uyum sorunlarını yordayan değişkenlerin belirlenebilmesi için Hiyerarşik Regresyon Analizi uygulanmıştır. Araştırmadan elde edilen sonuçlar incelendiğinde, kızların erkeklere göre uyum sorunlarının daha yüksek olduğu ve algılanan psikolojik kontrolün ergenlerin cinsiyetine göre farklılık göstermediği bulunmuştur. Erken dönem uyumsuz şemalar ile cinsiyet arasındaki ilişkide ise kopukluk ve reddedilmişlik, zedelenmiş özerklik ve performans ile aşırı tetikte olma baskılama/ ketleme şema alanlarında kızların lehine sonuçlar elde edilmiştir. Anne baba eğitim düzeylerinin psikolojik kontrol üzerinde anlamlı farklılık göstermediği görülmüştür. Annelerin eğitim düzeyleri yükseldikçe ergenlerin uyum sorunları puanlarının arttığı, babaların eğitim düzeyinin ise ergenlerde yalnızca olumlu benlik sorununda farklılaştığı görülmüştür. Şemalarda ise ebeveyn eğitim düzeyiyle anlamlı bir farklılık bulunmamıştır. Ebeveynleri boşanmış olan ya da ayrı yaşayan ergenlerin uyum sorunlarının evlilere göre daha yüksek olduğu görülmüştür. Psikolojik kontrol ve erken dönem uyumsuz şemaların birlikte uyum sorunlarının yordanmasında etkili olduğu sonucuna ulaşılmıştır.One of the most important stage in families is the adolesence period of their children. During this period, adolescents experience adjustment problems. Adolescents wants to be autonomic. Parents use different control types to bring under the control adolescents. The purpose of this study was to investigate the relationships between psychological control applied by parents, early maladaptive schemas and adolescents adjustment problems. For this purpose, 462 adolescents between the ages 13-16 selected in the current study. Psychological Control Scale, Early Maladaptive Schema Questionnaires Set for Children and Adolescents between the ages of 10-16, Reynolds Adaptive Survey Scale for Adolescents and a demographic information form were used to collect data. Independent samples t-test, hierarchical regression analysis and one-way anova tests were used to analyze the data. Results indicated that, paternal psychological control, disconnection and rejection schema, impaired limits schema, other- directedness schema and overvigilance and inhibition schema werefound as predicters of adjustment problems

Dispersion of finite-size particles probing inhomogeneous and anisotropic turbulence

A series of 8 laboratory experiments was used to investigate the dynamics of a few almost neutrally-buoyant finite-size particles in the entire volume of a rectangular tank open to air and filled with water. Stirring was achieved by a cylinder executing a two-dimensional periodic Lissajoux figure. The rate and direction of stirring by the cylinder was varied. The particle motions were analyzed using a tracking method developed for the experimental design. The Reynolds number associated with the large-scale stirring motion was in a turbulent range of [5,693-11,649] across all experiments. The absence of stirring in the direction of the cylinder axis, the constant interference of the cylinder with the eddies and the presence of walls and the free-surface resulted in a flow that was both inhomogeneous and anisotropic as recorded by the particle motion. Despite these unusual conditions, the single-particle dispersion across all experiments could be seen to follow a ballistic regime until about two-fifths of the particle Lagrangian velocity auto-correlation time T_L. It was followed by a brief diffusive regime between T_L and 2.5 T_L, after which the presence of the boundaries prevented further dispersion. Such evolution is consistent with classic predictions for fluid tracer dispersion in homogeneous and isotropic turbulence. Particle-pair dispersion was more complex. Both the fixed time-averaged and length-scale-dependent particle-pair dispersion rates averaged across pairs showed the ballistic dispersion regime, whereas the subsequent diffusive regime was better borne out by the length-scale-dependent particle-pair dispersion. A super-diffusive Richardson regime was not unmistakably detected. Substantial variability was however found across the different pairs of particles, which was linked to differences in the decorrelation time of the velocity difference as a result of the inhomogeneity of the turbulence. For short initial separations, some particle pairs had a better separation of the time scales delimiting the ballistic and diffusive regimes and showed hints of a brief Richardson regime

Benefits of the cooperative business model for small businesses

The cooperative model nowadays is very progressive. It reduces the risk of poverty, it helps the economy and social well-being. The cooperative business model can be found in every business sector as well as in the beekeeping sector. To understand the benefits of the cooperative business model this work will provide research into one of the most successful small business owners in Latvia. Andis is a beekeeper from Latvia who owns a cooperative business called “Medotava”. Medotava is a beekeeping company that was founded in 2017. Even though the company is small, it has grown radically in the business field within these years. Andis is also one of the members of the Latvian beekeeping association and he is one of the members of beekeeping cooperation. The reason why Andis and his cooperation is intriguing is that his love and passion for his work are truly admirable. Besides the work with bees and production, the owner of Medotava has also written European projects, where he got machinery for making the honey. Unfortunately, there is a barrier for the new entrepreneurs who would want to start their beekeeping business in Latvia, because of the little resources they have, and not all the entrepreneurs can get help from European projects. For this thesis, it was very important to find a valid and correct source as well as, to choose the most accurate qualitative method. To achieve better results, the author of the thesis used both a SWOT analysis and a Cost-benefit analysis. Besides these two analyses, the author had an interview with the Medotava owner and a survey that was sent to Latvian beekeepers for a better understanding of the research question. By the end of this paper, the main conclusion answering the CRQ will present all the benefits of the cooperative business model for small businesses. Therefore cooperative business model would be the perfect solution not only for beginners but also for existing entrepreneurs. The cooperative business model can be beneficial in many ways, for example, it can influence a company’s sales, logistics system, marketing companies, as well as reduce overall costs. This research will focus on these four aspects which will be proven through field and desk research

Transport et Fluctuations de Densité dans les Systèmes Désordonnés: Appliations à la Dispersion Atmophérique

The turbulent transport of particles is an important phenomena which appears in many natural and industrial processes. Understanding its properties, and, in particular, the creation of strong density fluctuations, is fundamental to improve models and refine forecasts. This can lead to significant benefits in issues related to economics, the environmental and health. A Lagrangian study of the tracer pair separation was carried out with the help of high resolution data analysis. This allowed us to point out the weaknesses of the mean-field approaches on which most models are based. For the separation, it is found that the transition from the regime of Batchelor (or ballistic) to that of Richardson (or explosive) occurs at times given by those typical of the turbulent kinetic energy dissipation. It is also found that Richardson's law can be reinterpreted in terms of diffusive behaviour of the velocity differences. Phenomenological arguments allow us to explain this effect through the decorrelation of the acceleration differences and the stationarity of the kinetic energy transfer ratio at large times. The high-order moments of both separation and velocity are also investigated to address the question of "violent events" in the distribution of the distances. Finally, a one-dimensional mass ejection model is proposed and used to examine the density fluctuations of heavy particles transported by the random environment.Le transport turbulent de particules est un phénomène important qui intervient dans de nombreux processus naturels et industriels. Comprendre ses propriétés et, en particulier, la création de grandes fluctuations de densité, est fondamental pour améliorer les modèles et affiner les prévisions. Cela représente de nombreux enjeux économiques, environnementaux et de santé. Une étude Lagrangienne de la séparation de paires de traceurs a été menée en s'appuyant sur l'analyse des données de simulations numériques à très haute résolution. Elle a permis de souligner les défaillances des approches de type champ moyen qui sont à la base des modèles les plus couramment utilisés. Pour la séparation, on constate que la transition entre le régime balistique de Batchelor et le régime explosif de Richardson a lieu à des temps données par le temps moyen de dissipation de l'énergie cinétique turbulente. Aussi, il est montré que la loi de Richardson peut s'interpréter comme un comportement diffusif des différences de vitesse. Des arguments phénoménologiques permettent d'interpréter cet effet par la décorrélation de différences d'accélération et la stationnarité aux temps longs du taux local de transfert d'énergie cinétique. Les moments d'ordres élevés de la séparation et de la vitesse sont aussi étudiés pour aborder la question des "événements violents" dans la distribution des distances. Enfin, un modèle d'éjection de masse est proposé et utilisé pour examiner les fluctuations de la densité de particules lourdes transportées dans un environnement aléatoire

Transport et Fluctuations de Densité dans les Systèmes Désordonnés: Appliations à la Dispersion Atmophérique

The turbulent transport of particles is an important phenomena which appears in many natural and industrial processes. Understanding its properties, and, in particular, the creation of strong density fluctuations, is fundamental to improve models and refine forecasts. This can lead to significant benefits in issues related to economics, the environmental and health. A Lagrangian study of the tracer pair separation was carried out with the help of high resolution data analysis. This allowed us to point out the weaknesses of the mean-field approaches on which most models are based. For the separation, it is found that the transition from the regime of Batchelor (or ballistic) to that of Richardson (or explosive) occurs at times given by those typical of the turbulent kinetic energy dissipation. It is also found that Richardson's law can be reinterpreted in terms of diffusive behaviour of the velocity differences. Phenomenological arguments allow us to explain this effect through the decorrelation of the acceleration differences and the stationarity of the kinetic energy transfer ratio at large times. The high-order moments of both separation and velocity are also investigated to address the question of "violent events" in the distribution of the distances. Finally, a one-dimensional mass ejection model is proposed and used to examine the density fluctuations of heavy particles transported by the random environment.Le transport turbulent de particules est un phénomène important qui intervient dans de nombreux processus naturels et industriels. Comprendre ses propriétés et, en particulier, la création de grandes fluctuations de densité, est fondamental pour améliorer les modèles et affiner les prévisions. Cela représente de nombreux enjeux économiques, environnementaux et de santé. Une étude Lagrangienne de la séparation de paires de traceurs a été menée en s'appuyant sur l'analyse des données de simulations numériques à très haute résolution. Elle a permis de souligner les défaillances des approches de type champ moyen qui sont à la base des modèles les plus couramment utilisés. Pour la séparation, on constate que la transition entre le régime balistique de Batchelor et le régime explosif de Richardson a lieu à des temps données par le temps moyen de dissipation de l'énergie cinétique turbulente. Aussi, il est montré que la loi de Richardson peut s'interpréter comme un comportement diffusif des différences de vitesse. Des arguments phénoménologiques permettent d'interpréter cet effet par la décorrélation de différences d'accélération et la stationnarité aux temps longs du taux local de transfert d'énergie cinétique. Les moments d'ordres élevés de la séparation et de la vitesse sont aussi étudiés pour aborder la question des "événements violents" dans la distribution des distances. Enfin, un modèle d'éjection de masse est proposé et utilisé pour examiner les fluctuations de la densité de particules lourdes transportées dans un environnement aléatoire