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We present results of Large-eddy simulations (LES) modeling of steady sheet and unsteady cloud cavitation on a two-dimensional hydrofoil which are validated against Particle image velocimetry (PIV) data. The study is performed for the angle of attack of 9° and high Reynolds numbers ReC of the order of 106 providing a strong adverse pressure gradient along the surface. We employ the Schnerr–Sauer and Kunz cavitation models together with the adaptive mesh refinement in critical flow regions where intensive phase transitions occur. Comparison of the LES and visualization results confirms that the flow dynamics is adequately reproduced in the calculations. To correctly match averaged velocity distributions, we propose a new methodology based on conditional averaging of instantaneous velocity fields measured by PIV which only provides information on the liquid phase. This approach leads to an excellent overall agreement between the conditionally averaged fields of the mean velocity and turbulence intensity obtained experimentally and numerically. The benefits of second-order discretization schemes are highlighted as opposed to the lower-order TVD scheme.

V nalogi obravnavamo teorijo (čistih) motivov, ki domnevno služi kot univerzalna kohomološka teorija v algebraični geometriji. Uvodoma se spomnimo osnovnih (Weilovih) kohomoloških teorij in motiviramo vpeljavo teorije motivov. V drugem poglavju pričnemo s ponovitvijo osnovne homološke algebre, kjer vpeljemo pojme kot so aditivna, psevdo-abelova in abelova kategorija. Tretje in četrto poglavje je namenjeno teoriji Tannaka kategorij, v četrtem poglavju jo spoznamo s stališča teorije skladov. V petem poglavju preko teorije algebraičnih ciklov vpeljemo pojem (čistega) motiva in dokažemo Jannsenov izrek o polenostavnosti kategorije numeričnih (čistih) motivov. In this Master's thesis we are concerned with the theory of (pure) motives, which is conjectured to serve as a universal or absolute cohomology theory in algebraic geometry. We begin with a reminder of the classical (Weil) cohomology theories for smooth projective varieties and give hints as to why we should believe that a theory of motives exists. In Chapter $2$, we recall some basic homological algebra, in particular we introduce the notions of additive, pseudo-abelian and abelian categories. We then discuss the theory of Tannakian categories in Chapters $3$ and $4$, where in Chapter 4 we consider the Tannakian theory from the viewpoint of stacks. In Chapter 5 we define the category of pure motives using the theory of algebraic cycles and prove Jannsen's theorem on the semi-simplicity of the category of numerical (pure) motives.

This paper deals with the fractional generalization of the integro-differential diffusion-wave equation for the Heisenberg sub-Laplacian, with homogeneous Bitsadze-Samarskii type time-nonlocal conditions. For the considered problem, we show the existence, uniqueness and the explicit representation formulae for the solution.

A stochastic algorithm is presented for a class of optimisation problems that arise when a group of agents compete to share a single constrained resource in an optimal manner. The approach uses intermittent single-bit feedback, which indicates a constraint violation and does not require inter-agent communication. The algorithm is based on a positive matrix model of AIMD, which is extended to the nonhomogeneous Markovian case. The key feature is the assignment of back-off probabilities to the individual agents as a function of the past average access to the resource. This leads to a nonhomogeneous Markov chain in an extended state space, and we show almost sure convergence of the average access to the social optimum.

We consider the pricing of American-type basket derivatives by numerically solving a partial differential equation (PDE). The curse of dimensionality inherent in basket derivative pricing is circumvented by using the theory of comonotonicity. We start with deriving a PDE for the European-type comonotonic basket derivative price, together with a unique self-financing hedging strategy. We show how to use the results for the comonotonic market to approximate American-type basket derivative prices for a basket with correlated stocks. Our methodology generates American basket option prices which are in line with the prices obtained via the standard Least-Square Monte-Carlo approach. Moreover, the numerical tests illustrate the performance of the proposed method in terms of computation time, and highlight some deficiencies of the standard LSM method. ispartof: Quantitative Finance vol:19 issue:10 pages:1689-1704 status: published

Este ensayo, de carácter argumentativo y de enfoque documental, presenta algunas reflexiones sobre las implicaciones de los modelos de Ciencia Abierta que vienen siendo promocionados desde ciertos gobiernos, empresas y entes multilaterales desde hace unos años, y que ahora con la sindemia se ha querido imponer aceleradamente. Este análisis se hace desde el estricto campo de la educación con la idea de fortalecer los procesos nacionales de ciencia y tecnología acordes con los estilos de desarrollo que, soberanamente, se vienen dando en países como el nuestro. En este ensayo se trata de reconstruir el proceso de promoción paulatina de un esquema de apertura de software, datos, procedimientos, resultados y publicaciones que culmina con la oferta masiva a distancia y sin control nacional de contenidos educativos. Se finaliza con algunas recomendaciones para establecer un modelo propio de compromiso de la ciencia y la tecnología, que sin cerrarse al mundo, lleve adelante la sincronía de su desarrollo con las necesidades y estrategias de un país soberano como el nuestro, dotado de un proyecto nacional.

International audience; We introduce two new approaches, called A-LSOB and N-MR, for boundary and interface-conjugate conditions on flat or curved surface shapes in the advection-diffusion lattice Boltzmann method (LBM). The Local Second-Order, single-node A-LSOB enhances the existing Dirichlet and Neumann normal boundary treatments with respect to locality, accuracy, and Peclet parametrization. The normal-multi-reflection (N-MR) improves the directional flux schemes via a local release of their nonphysical tangential constraints. The A-LSOB and N-MR restore all first- and second-order derivatives from the nodal non-equilibrium solution, and they are conditioned to be exact on a piece-wise parabolic profile in a uniform arbitrary-oriented tangential velocity field. Additionally, the most compact and accurate single-node parabolic schemes for diffusion and flow in grid-inclined pipes are introduced. In simulations, the global mass-conservation solvability condition of the steady-state, two-relaxation-time (S-TRT) formulation is adjusted with either (i) a uniform mass-source or (ii) a corrective surface-flux. We conclude that (i) the surface-flux counterbalance is more accurate than the bulk one, (ii) the A-LSOB Dirichlet schemes are more accurate than the directional ones in the high Peclet regime, (iii) the directional Neumann advective-diffusive flux scheme shows the best conservation properties and then the best performance both in the tangential no-slip and interface-perpendicular flow, and (iv) the directional non-equilibrium diffusive flux extrapolation is the least conserving and accurate. The error Peclet dependency, Neumann invariance over an additive constant, and truncation isotropy guide this analysis. Our methodology extends from the d2q9 isotropic S-TRT to 3D anisotropic matrix collisions, Robin boundary condition, and the transient LBM.

Psychoactive drug use is a significant problem for most Western societies. It has been a growing problem in Ireland over the last five decades, causing a multitude of problems for individuals and communities. One of the primary rehabilitative responses available for individuals in Ireland desiring to undertake recovery is the drug rehabilitation Special Community Employment (SCE) programme. The SCE programme supports almost one thousand individuals in their recovery by maintaining stabilisation, reinforcing recovery, providing education and skills training, and developing recovery capital enabling the participant to re-enter society as a contributing member. A review of the literature on SCE indicates that several issues have arisen around funding structures, administration, governance and operations (Bruce 2004; Lawless 2006; CityWide 2013). However, little action has been taken over the last decade to address these issues. The studies referred to, adopted a broad view of the SCE programme. They examined activity across a wide range of stakeholders, including participants, families, workers, community boards and state bodies. While these studies provided excellent information, there was an evident paucity of research focused on the professional and support staff who deliver SCE in local community projects. This research study was undertaken in response to that gap in the literature.It sought to provide some insight into the SCE workers' experiences, which would contribute to the debate on operations and practices in SCEs and policy formation in the broader rehabilitation field. The research used a mixed-methods design methodology consisting of an initial questionnaire to gather quantitative data and a series of semi-structured interviews that provided qualitative data, which enhanced and elaborated on the data gathered at the quantitative phase. This mixed-methods design provided a pragmatic approach that saw both qualitative and quantitative data generated and analysed. Results suggest that SCE workers at all levels have experienced significant challenges to their effectiveness in work and their professional training and development needs. These issues are perceived to arise from the policies, procedures, administration and working conditions under which they operate within the SCE programmes. This research revealed that while social, economic policy and drug policy in Ireland has changed radically over the past decade, the SCE programme has failed to adapt in a way that adequately meets the needs of this changing environment. Several recommendations are made on foot of this study, which if adopted, would improve working conditions, enhance worker training and development and increase the effectiveness of service delivery.

In this work, we consider the general family of the so called ADER$$P_NP_M$$PNPMschemes for the numerical solution of hyperbolic partial differential equations witharbitraryhigh order of accuracy in space and time. The family of one-step$$P_NP_M$$PNPMschemes was introduced in Dumbser (J Comput Phys 227:8209–8253, 2008) and represents a unified framework for classical high order Finite Volume (FV) schemes ($$N=0$$N=0), the usual Discontinuous Galerkin (DG) methods ($$N=M$$N=M), as well as a new class of intermediate hybrid schemes for which a reconstruction operator of degreeMis applied over piecewise polynomial data of degreeNwith$$M>N$$M>N. In all cases with$$M \ge N > 0 $$M≥N>0the$$P_NP_M$$PNPMschemes arelinearin the sense of Godunov (Math. USSR Sbornik 47:271–306, 1959), thus when considering phenomena characterized by discontinuities, spurious oscillations may appear and even destroy the simulation. Therefore, in this paper we present a new simple, robust and accurate a posteriori subcell finite volume limiting strategy that is valid for the entire class of$$P_NP_M$$PNPMschemes. The subcell FV limiter is activated only where it is needed, i.e. in the neighborhood of shocks or other discontinuities, and is able to maintain the resolution of the underlying high order$$P_NP_M$$PNPMschemes, due to the use of a rather fine subgrid of$$2N+1$$2N+1subcells per space dimension. The paper contains a wide set of test cases for different hyperbolic PDE systems, solved on adaptive Cartesian meshes that show the capabilities of the proposed method both on smooth and discontinuous problems, as well as the broad range of its applicability. The tests range from compressible gasdynamics over classical MHD to relativistic magnetohydrodynamics.

В данной работе представлена электрическая часть атомной электростанции с реакторами ВВЭР-1000 мощностью 3Ñ 1000 МВт. Представлены методы выбора основного оборудования, главной ÑÑ ÐµÐ¼Ñ‹ ÑÐ»ÐµÐºÑ‚Ñ€Ð¸Ñ‡ÐµÑÐºÐ¸Ñ ÑÐ¾ÐµÐ´Ð¸Ð½ÐµÐ½Ð¸Ð¹, ÑÑ ÐµÐ¼Ñ‹ ÑÐ¾Ð±ÑÑ‚Ð²ÐµÐ½Ð½Ñ‹Ñ Ð½ÑƒÐ¶Ð´. Проведен расчёт токов короткого замыкания для выбора ÑÐ»ÐµÐºÑ‚Ñ€Ð¸Ñ‡ÐµÑÐºÐ¸Ñ Ð°Ð¿Ð¿Ð°Ñ€Ð°Ñ‚Ð¾Ð² и проводников. Рассчитаны Ð¿ÐµÑ€ÐµÑ Ð¾Ð´Ð½Ñ‹Ðµ ÑÐ»ÐµÐºÑ‚Ñ€Ð¾Ð¼ÐµÑ Ð°Ð½Ð¸Ñ‡ÐµÑÐºÐ¸Ðµ процессы в системе ÑÐ¾Ð±ÑÑ‚Ð²ÐµÐ½Ð½Ñ‹Ñ Ð½ÑƒÐ¶Ð´. Проведена оценка успешности самозапуска электродвигателей ÑÐ¾Ð±ÑÑ‚Ð²ÐµÐ½Ð½Ñ‹Ñ Ð½ÑƒÐ¶Ð´. Произведен расчет времени пуска главного циркуляционного насоса. Выбраны кабели ÑÐ¾Ð±ÑÑ‚Ð²ÐµÐ½Ð½Ñ‹Ñ Ð½ÑƒÐ¶Ð´ и проверены по условиям термической стойкости и невозгораемости., This paper presents the electrical part of a nuclear power plant with VVER-1000 reactors with a capacity of 3x1000 MW. Methods for selecting the main equipment, the main wiring diagram, and auxiliaries are presented. The calculation of short-circuit currents for the selection of electrical devices and conductors has been carried out. Transient electromechanical processes in the auxiliary system are calculated. Evaluation of the success of self-starting of auxiliary electric motors has been carried out. The calculation of the start-up time of the main circulation pump has been made. Cables for auxiliary needs were selected and tested for thermal resistance and non-flammability conditions.

Straipsnyje pristatomos kognityvinės poetikos galimybės analizuojant sudėtingus, daugiasluoksnius intelektualiosios lietuvių literatūros tekstus ir bandant užčiuopti formaliuosiuose elementuose slypinčią šio tipo tekstų specifiką ir gylį. Remiantis Peterio Stockwello siūloma kognityvinės poetikos koncepcija, aptariamos schemų, kognityvinės deiksės ir deiktinio perkėlimo sąvokos, leidžiančios ištirti ir apibūdinti teksto konstravimo principus. Šaltiniu pasirinkta intelektualiosios literatūros atstovu vadinamo Ramūno Klimo apysaka "Gintė ir jos žmogus". Kognityvinės poetikos aspektu išanalizavus Klimo apysakai būdingas schemas ir deiksių naudojimą, tokios priemonės, kaip įvairių deiktinių kategorijų maišymas, schemų pertvarkymas, laikomos vienu būdų skaitymo procese nuolat kurstyti skaitytojo smalsumą ir dėmesį. Kartu šios priemonės sulėtina skaitymo procesą, apsunkina teksto suvokimą ir interpretaciją – taip aktyvuojama Reuveno Tsuro apibūdinama uždelstoji kategorizacija. Kad šis struktūriškai sudėtingas Klimo tekstas būtų iki galo suprantamas, išryškėtų minėtų rašymo formų prasmės, jis turėtų būti skaitomas pasitelkus ezopinį kodą, aktualizuojamą tekste esančių užuominų apie sovietinio, autoriaus gyvento, laikotarpio kritiką. Remiantis Klimo apysaka daroma išvada, kad paslėptam pranešimui koduoti intelektualiosios literatūros tipas itin parankus būtent dėl aktyvuojamos uždelstosios kategorizacijos, reikalaujančios mentalinių pastangų, – taip skaitytojas paruošiamas refleksijoms, būtinoms ezopiniam pranešimui suprasti. Using the approach of cognitive poetics, the author of the article analyses Ramūnas Klimas’ story, Gintė ir jos žmogus [Gintė and Her Man]. By employing Peter Stockwell’s concept of cognitive deixis, the technique of deictic transfer and aspects of schema theory in the text, the fundamental mechanisms of the construction of the story have been highlighted, which in turn, lead to the observation that the text provokes the delayed categorization discussed by Reuven Tsur. In the text, the deictic center of the implicit reader is being developed in different temporal and spatial dimensions using deixis of the respective categories. The interpretation is complicated by the highlighting of the textual deixis: several versions of the same story are presented, the process of the narration itself is commented, and the reader is addressed directly, which, according to Stockwell, can be understood as an attempt to destroy the reader’s belief in the truthfulness of the story being told and to put them out. These formal features also determine the depth and multi-layered nature of the text. Looking at the formal elements of the text and the techniques it employs from the point of view of cognitive poetics, the story by Klimas can be viewed as an attempt to criticize the official Soviet discourse and undermine the dangers of trusting blindly the truth proclaimed by one man.

International audience; This study aims to better understand how experienced school teachers think about, organize, control and guide an inquiry-based science teaching-learning situation. The framework of conceptualization in action, complemented by a dynamic model of intentions, allows us to uncover the intentions underlying the preparations for each session, and to identify the cues taken into account by each teacher to actualize these intentions in the classroom situation. Our methodological tools are borrowed from the ergonomic approaches of work psychology and the results presented in this paper target the didactic intentions related to the knowledge at stake.; Cette étude vise à mieux comprendre comment des professeurs des écoles expérimentés pensent, organisent, contrôlent et guident une situation d’enseignement-apprentissage des sciences fondée sur l’investigation. Le cadre de la conceptualisation dans l’action complété d’un modèle dynamique des intentions nous permet de mettre au jour des intentions sous-jacentes aux préparations de chaque séance, et d’identifier les indices pris en compte par chaque enseignant pour actualiser ces intentions en situation de classe. Nos outils méthodologiques sont empruntés aux approches ergonomiques de la psychologie du travail et les résultats présentés dans cette communication ciblent les intentions didactiques relatives aux savoirs en jeu.

Presented thesis deals with the question of whether pre-service and in-service teachers are capable of didactic transformation. The aim was to assess the extent to which they are able to create a simplified version of complicated professional illustrations, which they would present in the teaching of human biology to pupils in the eighth grade of lower-secondary school. Drawing was used as the main research tool and the research was intentionally performed on the two mentioned groups of respondents in order to monitor the differences between pre-service teachers and those teachers who already have practical experiences with didactic transformation. The thesis also contains an analysis of the most frequently used textbooks in the teaching of human biology at primary school. Drawings of teachers and students were evaluated using predetermined evaluation criteria. It was found that all respondents demonstrated a very good ability of didactic transformation. Both pre - service and in-service teachers had an excellent knowledge of the content, but the in-service teachers had a more developed didactic level of mediating the curriculum to students, which confirms the fact that they chose only the most fundamental concepts and the drawings were rather schematic. Unlike pre-servise teachers, in-servise teachers drew a scheme step by step. They mastered it during the ongoing interpretation and they tried to explain the overall issues of the topic on real-life examples.

The starting point for algebraic geometry was the study of algebraic sets, that is the study of the locus of points satisfying a set of polynomial equations. The geometric properties of such sets are encoded inside the rings of functions that are naturally defined on such sets. In this book we develop both the more abstract theory of schemes and the classical approach in terms of Riemann surfaces and algebraic function fields over a field of arbitrary characteristic., Η αλγεβρική γεωμετρία ξεκίνησε από τη μελέτη των αλγεβρικών συνόλων, δηλαδή του γεωμετρικού τόπου των σημείων που ικανοποιούν ένα σύστημα πολυωνυμικών εξισώσεων. Αρκετά νωρίς έγινε σαφές ότι οι γεωμετρικές ιδιότητες τέτοιων συνόλων βρίσκονται κρυμμένες μέσα στις συναρτήσεις που ορίζονται με φυσιολογικό τρόπο πάνω στα αντικείμενα αυτά. Στο παρόν βιβλίο αναπτύσσεται τόσο η γενική θεωρία των σχημάτων όσο και η κλασική προσέγγιση των αλγεβρικών καμπυλών μέσω των επιφανειών Riemann αλλά και των αλγεβρικών σωμάτων συναρτήσεων πάνω από ένα σώμα οποιασδήποτε χαρακτηριστικής.

In the presented diploma thesis we deal with a nonlinear way of structuring the curriculum using conceptual maps. The aim of the work is to find out to what extent concept can conceptual or mind maps help students to structure and remember the information to which they are exposed during the educational process. The work is divided into two parts - theoretical and empirical, in total it is divided into six chapters. In the first chapter we deal with the content of school education and more detailed we deal with education and training, along with other aspects related to them. The second chapter deals specifically about the schol subject Technology at primary schools in Slovakia. The third chapter deals with the issue of teaching methods, while analyzing in detail innovative teaching methods. The fourth chapter focuses specifically on conceptual maps as a new activating and motivating approach to knowledge acquisition. The fifth chapter is included in the empirical part of the work. This chapter describes the understanding of the work within the methodology of the researched problem, problem definition, goals, hypotheses, the selection of students' research sample and methodological sheets enriched with the overall course, worksheet and conceptual maps by which the teacher writes students as a means of determining curricula for students. The sixth chapter characterizes the choice of research tools. This chapter also describes the evaluation of the research, but only briefly. The evaluation of the research was not possible to do because of the global pandemic situation associated with Covid-19. At the end of the diploma thesis, we evaluate the entire course of research on the basis of school lessons taken with students who formed a research sample of the experiment.

Explicit stabilized integrators are an efficient alternative to implicit or semi-implicit methods to avoid the severe timestep restriction faced by standard explicit integrators applied to stiff diffusion problems. In this paper, we provide a fully discrete strong convergence analysis of a family of explicit stabilized methods coupled with finite element methods for a class of parabolic semilinear deterministic and stochastic partial differential equations. Numerical experiments including the semilinear stochastic heat equation with space-time white noise confirm the theoretical findings., Comment: Assyr Abdulle passed away on September 1st, 2021 prior to the revision of this paper. To appear in IMA Journal of Numerical Analysis

Understanding the emergence of teaching practices is a challenge for research and training. We explore here the practices of five teachers first-time using programming language or robots. Using instrumental and ergonomic frames (schemes, instrumental geneses and distance) and professional didactics (new activity draws on old known practices), our results concern a reduction of distance to old practices and the existence of new didactic reference points., Les programmes de mathématiques incluent algorithmique et informatique désormais dès le primaire. Comprendre l’évolution des pratiques enseignantes est alors un enjeu pour la recherche et la formation. L’article analyse les pratiques de cinq enseignants qui intègrent pour la première fois Scratch ou des robots. Nos cadres en didactique des mathématiques utilisent des approches instrumentale et ergonomique (schèmes, genèse et distance instrumentales) et de la didactique professionnelle (recours à des pratiques connues pour en bâtir de nouvelles). Deux phénomènes sont montrés : une réduction de la distance permettant ce recours aux anciennes pratiques et une prise de repères didactiques. Distance et repères semblent ainsi un outil intéressant pour comprendre l’activité en situation nouvelle., Haspekian Mariam,Gelis Jean-Michel. Informatique, Scratch et robots : de nouvelles pratiques enseignantes en mathématiques ?. In: Sciences et Technologies de l'Information et de la Communication pour l'Éducation et la Formation, volume 28 n°1, 2021. pp. 13-49.