Работа посвящена моделированию устройства затравки для машины непрерывного литья заготовки(МНЛЗ) ЭСПЦ ПАО "ММК" в программном пакете Matlab. В первом разделе: описаны основные виды разливки стали, выполнен обзор конструкции аналогичных МНЛЗ по литературным материалам, что позволило рассмотреть конструктивные особенности аналогичных машин, технических характеристик и принципов действия МНЛЗ. А так же была рассмотрена работа кристаллизатора МНЛЗ, конструкция устройства затравки в ЭСПЦ ПАО «ММК». Во втором разделе: описана общие особенности гидроприводов, далее описан гидропривод устройства затравки, рассчитан и выбран гидроцилиндр(ГЦ), рассчитаны основные расходы жидкости в ГЦ, проверена устойчивость ГЦ во время работы, расчёт произведён в системе компьютерной алгебры Matcad, выбрана рабочая жидкость, а так же её альтернатива. Раздел три посвящен: построению кинематики и постановке кинематических связей механизма затравки в Matlab, построению 3d моделей основных частей устройства, настройке рабочих блоков, а так же настройке работы тянущей клети. Раздел четыре посвящен: построению гидропривода механизма затравки в Matlab, построению рабочих блоков и их настройка, настройке работы распределителя гидропривода, переводу сигнала гидравлики в возвратно- поступательную работу кинематики. Пятый раздел подводит итоги работы: проверка результатов и их анализ, а так же предложения по дальнейшей модернизации системы. / This work is devoted to simulation of the dummy bar for the continuous casting machine of the electric furnace shop of Public Joint Stock Company " Magnitogorsk Iron and Steel Works" in the "Matlab" environment. In the first section: the main types of steel casting are described, a review of the design of similar CCM’s according to literary materials is carried out, which allowed us to consider the design features of similar machines, technical characteristics and principles of operation of CCM. The work of the CCM crystallizer, the design of the dummy bar in the electric furnace shop of MMK PJSC was considered as well. In the second section: the general features of hydraulic drives are described, the hydraulic drive of the dummy bar is further described, the hydraulic cylinder (HC) is calculated and selected, the main fluid flow rates in HC are calculated, the stability of HC during operation is checked, the calculation is made in the Mathcad computer algebra system, the working fluid is selected, as well as its alternative. Section three is devoted to: building kinematics and setting kinematic connections of the dummy bar in Matlab, building 3d models of the main parts of the device, setting up working blocks, as well as setting up the operation of the withdrawal-roll set. Section four is devoted to: the construction of the hydraulic drive of the dummy bar in Matlab, the construction of working blocks and their adjustment, the adjustment of the hydraulic drive distributor, the translation of the hydraulics signal into the reciprocating operation of kinematics. The fifth section summarizes the results of the work: verification of the results and their analysis, as well as proposals for further modernization of the system.

Children and youth choirs in the Southern Baptist Church have historically been used as a training ground for future adult choir members. These future choristers received a musical education from music ministers utilizing a graded choral curriculum. More recently, youth choir leaders, who are often volunteers, no longer receive educational materials to aid in the musical education of the children and youth choirs. This change is of concern, given the importance of pedagogical approaches and repertoire selection to the vocal health, self-awareness, and identity of young singers. The purpose of this study was to investigate the pedagogical practices and repertoire used by youth choir directors in SBC youth choir rehearsals. Using Gackle’s (2011, 2019) pedagogical framework for vocal health, I sought to identify what vocal training, repertoire selection, and rehearsal methods are used by SBC youth choir directors, as it relates to the female adolescent voice. Utilizing a collective case study approach, I conducted interviews with youth choir directors and youth choir members in SBC of Virginia churches, completed observations of female adolescents who sang in the choirs, and completed document review of repertoire used in these choirs. Interviews centered around participants’ general knowledge, preparation, and perceptions regarding choral rehearsal techniques. For the observations, I observed a performance of a song of each female adolescent participant’s choice, to evaluate their vocal technique while singing. I conducted a critical analysis of the music literature used in rehearsal by the youth choirs involved in the study. I enlisted a committee of five musicians, who were either educators who had church youth choir experience or were music ministers who worked with female adolescents in youth choir, to review the repertoire utilizing a Repertoire Assessment Protocol I developed using criteria from Gackle (2011, 2019). I completed initial coding of all data to discover what vocal pedagogical concerns, if any, leaders considered and utilized during rehearsal. I then completed second cycle coding to find common themes connecting the repertoire analysis, interviews, and observations. Although the youth choir directors considered their repertoire and techniques to be appropriate for their young singers, in five out of six situations, the repertoire and rehearsal techniques did not fulfill healthful and pedagogically appropriate criteria as outlined by Gackle (2011, 2019). The female adolescents exhibited vocal tension and strain while singing but still expressed a deep respect and appreciation for their youth choir leaders. Most of the singers mentioned that they admired their youth leaders’ strong walk with Christ, and the students expressed a desire to follow this example spiritually and musically. Out of ten foundational techniques for healthy vocal production, the students and directors disagreed in their perspectives on five: tone production, breath management, important singing skills, vowels, and intonation. In general, the students stated that their directors had not addressed these items in rehearsal as often as the directors stated. Additionally, the directors’ opinions of repertoire appropriateness differed from that of the repertoire committee, who stated that the Contemporary Christian Music they examined was not conducive for female adolescent vocal development. With many obstacles to youth choir programs in church, the future of youth choir in the SBC church is in question. In this study, pastoral lack of support, competition with youth bands, lack of qualified leadership, and lack of quality repertoire availability all appeared related to a decline in youth choir membership. Youth choir leaders may improve the pedagogy in rehearsal by increasing their knowledge of the adolescent voice, seeking out reputable publishers who have curated music that is conducive to supporting adolescent voices, and finding healthful repertoire or by adjusting current repertoire to fit the capabilities of their singers.

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No description available.

The reprogrammable nature of configurable computing machines has led to a wealth of research in run-time reconfigurable systems and applications. A limitation often encountered in this research is the slow configuration time with respect to the system clock speed. One technique to deal with these configuration delays has been to develop devices that can hold multiple rapidly interchangeable configurations. This technique is known as context-switching. This thesis discusses the development of a framework to support applications which execute on a run-time reconfigurable system containing context-switching devices. The framework is divided into a number of layers: hardware, middleware, software, and applications. The design, implementation, and details of each layer are presented. / Master of Science

Digitally controlled inkjet printing technology has attractive features for the production of catalyst coated membranes (CCM) for application either in electrolysers or in fuel cells. There are a number of unique features: pattern like coating for effective use of expensive materials like platinum or iridium, direct deposition onto membrane material, non-impact printing, easy change of pattern design, and ability to generate catalytic gradients. Employing inkjet printing technology enables the manufacturing of catalytic layers as well as other components. The challenges are to evaluate process-compatible inks as well as processing parameters. / Die digital gesteuerte Inkjetdrucktechnologie hat attraktive Eigenschaften für die Herstellung von katalysatorbeschichteten Membranen (CCM), die entweder in Elektrolyseuren oder in Brennstoffzellen eingesetzt werden. Es gibt eine Reihe einzigartiger Merkmale: mustergenaue Beschichtung für den effektiven Einsatz teurer Materialien wie Platin oder Iridium, direkte Bedruckung des Membranmaterials, berührungsfreies Drucken, einfache Änderung des Druckdesigns und die Fähigkeit, katalytische Gradienten zu erzeugen. Der Einsatz der Inkjetdrucktechnologie ermöglicht die Herstellung von katalytischen Schichten und anderen Komponenten. Die Herausforderungen bestehen darin, prozesskompatible Tinten sowie Verarbeitungsparameter zu evaluieren.

The wall effect is known to present difficulties when attempting to predict the pressure drop over randomly packed beds. The Nuclear Safety Standard Commission, “Kerntechnischer Auss-chuss" (KTA), made considerable efforts to develop an equation which predicts the pressure drop over cylindrical randomly packed beds consisting of mono-sized spheres. The KTA was able to estimate a limiting line, which defines the region for which the wall effect is negligible, however the theoretical basis for this line is unclear. The goal of this investigation was to determine the validity of the KTA limiting line, using an explicit approach. Packed beds were generated using Discrete Element Modelling (DEM), and the flow through the beds simulated using Computational Fluid Dynamics (CFD). STAR-CCM+R was used for both DEM and CFD operations, and the methods developed for this explicit approach were validated with empirical data. The KTA correlation predictions for friction factors were com- pared with the CFD results, as well as the predictions from a few other correlations. The KTA correlation predictions for friction factors did not correspond well with the CFD results at low aspect ratios and low modified Reynolds numbers, due to the influence of the wall effect. The KTA limiting line was found to be valid, but not exact. A new limiting line for the KTA correlation was suggested, however the new limiting line improved little on the existing line and was the result of some major assumptions. In order to improve the determination of the position of the KTA limiting line further, criteria need to be established which determine how small the error in predicted friction factor must be before the KTA correlation can be accepted as accurate. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

The wall effect is known to present difficulties when attempting to predict the pressure drop over randomly packed beds. The Nuclear Safety Standard Commission, “Kerntechnischer Auss-chuss" (KTA), made considerable efforts to develop an equation which predicts the pressure drop over cylindrical randomly packed beds consisting of mono-sized spheres. The KTA was able to estimate a limiting line, which defines the region for which the wall effect is negligible, however the theoretical basis for this line is unclear. The goal of this investigation was to determine the validity of the KTA limiting line, using an explicit approach. Packed beds were generated using Discrete Element Modelling (DEM), and the flow through the beds simulated using Computational Fluid Dynamics (CFD). STAR-CCM+R was used for both DEM and CFD operations, and the methods developed for this explicit approach were validated with empirical data. The KTA correlation predictions for friction factors were com- pared with the CFD results, as well as the predictions from a few other correlations. The KTA correlation predictions for friction factors did not correspond well with the CFD results at low aspect ratios and low modified Reynolds numbers, due to the influence of the wall effect. The KTA limiting line was found to be valid, but not exact. A new limiting line for the KTA correlation was suggested, however the new limiting line improved little on the existing line and was the result of some major assumptions. In order to improve the determination of the position of the KTA limiting line further, criteria need to be established which determine how small the error in predicted friction factor must be before the KTA correlation can be accepted as accurate. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

The newest European high performance material testing reactor, the Jules Horowitz Reactor, is under construction at CEA Cadarache research center in France. The reactor will support existing and future nuclear reactor technologies, with the first criticality expected at the end of this decade. The current/reference CEA methodology for simulating the thermalhydraulic behavior of the reactor gives reliable results. The CATHARE2 code simulates the full reactor circuit with a simplified approach for the core. The results of this model are used as boundary conditions in a three-dimensional FLICA4 core simulation. However this procedure needs further improvement and simplification to shorten the computational requirements and give more accurate core level data. The reactor’s high performance (e.g. high neutron fluxes, high power densities) and its design (e.g. narrow flow channels in the core) render the reactor modeling challenging compared to more conventional designs. It is possible via thermal-hydraulic or solely hydraulic Computational Fluid Dynamics (CFD) simulations to achieve a better insight of the flow and thermal aspects of the reactor’s performance. This approach is utilized to assess the initial modeling assumptions and to detect if more accurate modeling is necessary. There were no CFD thermal-hydraulic publications available on the JHR prior to the current PhD thesis project. The improvement process is split into five steps. In the first step, the state-of-the-art CEA methodology for thermal-hydraulic modeling of the reactor using the system code CATHARE2 and the core analysis code FLICA4 is described. In the second and third steps, a CFD thermal-hydraulic simulations of the reactor’s hot fuel element are undertaken with the code STAR-CCM+. Moreover, a conjugate heat transfer analysis is performed for the hot channel. The knowledge of the flow and temperature fields between different channels is important for performing safety analyses and for accurate modeling. In the fourth step, the flow field of the full reactor vessel is investigated by conducting CFD hydraulic simulations in order to identify the mass flow split between the 36 fuel elements and to describe the flow field in the upper and lower plenums. As a side study a thermal-hydraulic calculation, similar to those performed in previous steps is undertaken utilizing the outcome of the hydraulic calculation as an input. The final step culminates by producing an improved, more realistic, purely CATHARE2 based, JHR model, incorporating all the new knowledge acquired from the previous steps. The primary outcome of this four year PhD research project is the improved, more realistic, CATHARE2 model of the JHR with two approaches for the hot fuel element. Furthermore, the project has led to improved thermal-hydraulic knowledge of the complex reactor (including the hot fuel element), with the most prominent findings presented. / <p>QC 20161208</p> / DEMO-JHR

The Earth’s atmosphere constitutes a complex system subject to a large number of forcings of both natural and anthropogenic origin; these influence its evolution on a range of timescales. This thesis makes use of the UMUKCA global chemistry-climate model to explore several aspects relating to the atmospheric response to the 11-year solar cycle forcing and future stratospheric ozone recovery. Firstly, following recent improvements in the model, the atmospheric response to the solar cycle forcing simulated in UMUKCA is discussed. It is shown that while some features show a broad resemblance to observations/reanalysis, there are clear differences with regard to other features; the latter could result from model deficiencies and/or uncertainties in the observed response. The role of analysis method and of interannual variability is also addressed. Secondly, the solar cycle response is separated into the individual contributions from direct radiative heating and from ozone production using a set of sensitivity experiments. It is shown that while the tropical yearly mean responses to the two components are generally linearly additive, this is not necessarily the case in the high latitudes. It is suggested that solar-induced ozone changes could be important for modulating the Southern Hemisphere dynamical response. Thirdly, the role of the representation of the solar ozone response is studied. It is shown that the choice of the solar ozone response prescribed in the radiation scheme in non-interactive ozone experiments has a substantial impact on the simulated temperature response to the solar cycle forcing. The Northern Hemisphere dynamical responses are found to be generally similar within the uncertainty. A comparison with an interactive ozone case is also discussed. Lastly, future ozone recovery is investigated using a seven-member ensemble of 1960- 2099/1980-2080 integrations. The long-term evolution of ozone in different regions is found to be generally consistent with previous modelling studies. The long-term trends and variability in springtime Arctic ozone and its chemical, radiative and dynamical drivers are assessed. It is shown that Arctic ozone increases in the future, consistent with future reduction in stratospheric chlorine, stratospheric cooling and strengthening large-scale circulation. Yet, the large interannual variability is found to continue and to facilitate episodic ozone reductions, with halogen chemistry becoming a smaller but non-negligible driver of future springtime Arctic ozone variability for many decades.