Variations in the electricity consumption and production connected to the power system have to be balanced by active control. Hydropower is the most important balancing resource in the Nordic system, and will become even more important as the share of variable renewable energy sources increases. This thesis concerns balancing of active power, especially the real-time balancing called frequency control. The thesis starts in a description of the situation today, setting up models for the behaviour of hydropower units and the power system relevant to frequency control, and comparing the models with experiments on several hydropower units and on the response of the Nordic grid. It is found that backlash in the regulating mechanisms in hydropower units have a strong impact on the quality of the delivered frequency control. Then, an analysis of what can be done right now to improve frequency control and decrease its costs is made, discussing governor tuning, filters and strategies for allocation of frequency control reserves. The results show that grid frequency quality could be improved considerably by retuning of hydropower governors. However, clear technical requirements and incentives for good frequency control performance are needed. The last part of the thesis concerns the impact from increased electricity production from variable renewable energy sources. The induced balancing need in terms of energy storage volume and balancing power is quantified, and it is found that with large shares of wind power in the system, the energy storage need over the intra-week time horizon is drastically increased. Reduced system inertia due to higher shares of inverter connected production is identified as a problem for the frequency control of the system. A new, linear synthetic inertia concept is suggested to replace the lost inertia and damping. It is shown that continuously active, linear synthetic inertia can improve the frequency quality in normal operation and decrease wear and tear of hydropower units delivering frequency control.

Developmental transitions are experienced throughout the life-span and necessitate adapting to significant and unpredictable changes (Heckhausen et al., 2010; Perry, 2003). The shift from high school to university in young adulthood serves as an exemplar of how these challenging junctures can undermine motivation and well-being. Recent evidence suggests that most (85%) young adults making this transition feel overwhelmed, half (50%) experience immense anxiety (ACHA, 2012), and more than one quarter (28%) withdraw from their institutions by the end of their first year (Snyder & Dillow, 2013). The present dissertation was designed to counter these developments by conducting a systematic analysis of whether motivation-focused thinking (selective secondary control) sustained young adults’ goal striving, goal attainment, and well-being based on propositions stemming from the motivational theory of life-span development (Heckhausen et al., 2010). Study 1 comprised a seven-month field study and showed that motivation-focused selective secondary control striving positively predicted young adults use of behavior-focused selective primary control strategies, which in turn influenced academic performance. Study 2 was based on a seven-month field study and built on Study 1 by demonstrating that increasing selective secondary control striving was related to lower levels of depressive and stress-related physical symptoms for young adults with low high school grades. These effects were mediated by theoretically-derived mechanisms involving selective primary control and discrete emotions. Building on the preceding studies, Study 3 involved a seven-month, pre-post, field design and showed that students with low high school grades and high perceived control who received a motivation-enhancing selective secondary control treatment attained year-end course grades that were 8% higher than their no-treatment peers (74.85% vs. 66.68%). Consistent with theory, treatment effects were mediated by selective secondary and primary control strategies and emotions. Findings from these studies advance the literature by documenting previously unexplored antecedents, consequences, mediators, moderators, and manipulations (treatment) of selective secondary control for young adults in the midst of a challenging life course transition. / October 2016

The use of the Alexander Technique in teaching, performing and practicing the flute is investigated, in order to determine how to apply the Technique to the art of producing a good flute tone. The author's application of the Alexander Technique to teaching and playing the flute is described. Knowledge was acquired both through doing case studies on two flute pupils, and through the integration of personal experience, gained through taking Alexander Technique lessons, into flute lessons. This is set out in detail. The decision to work intensively on the technique of sound production on the flute, made the author aware of the fact that we. as teachers and performers, encounter a large number of different problems in teaching and playing. Matters are complicated by a pupil's eagerness and "wanting to do things right". This can cause a certain amount of apprehension and even anxiety. Often the habits which inhibit progress prove very difficult for the teacher to correct. This study is aimed at detecting and solving these problems by using the Alexander Technique; hopefully leading to a better understanding of how the Technique can be applied to flute teaching and playing. Posture, breathing and embouchure control are specifically addressed. For the teacher or performer who has little understanding of his/her own problems in playing the flute - e.g. in coping with the loss of a good tone caused by stage fright and other anxieties - the use of the Alexander Technique can mean the creation a new sense of physical freedom and mental flexibility. A knowledge of how to work on changing faulty habits and the creating of new and better means of body use, can be gained through the taking of Alexander IV Technique lessons. The general principles and various applications of the Technique are described. The problems musicians face - e.g. postural problems from sitting or standing for hours while practicing the instrument, instrument-specific problems such as pain in the arms or shoulders, or physical tension caused by anxiety - are all habitual difficulties which can be detected, weakened and, hopefully, even erased through the use of the Alexander Technique. This study aims to show that mind-body awareness work is fundamental for the teacher, the pupil and the performer. Very often, what appear to be simple problems in musical performance are bound to deeply-felt and long-standing emotions and experiences. Therefore, the seemingly simple problems associated with producing a good flute tone cannot be addressed without dealing with the person as a whole. It is thus crucial for us as musicians to attend to the whole person - as we practice, perform and teach. This study attempts to lead musicians to a better understanding of all facets of themselves and others, through the application of the Alexander Technique. / Dissertation (MMus (Performing Arts))--University of Pretoria, 2006. / Music / unrestricted

This research focuses on frequency control ancillary services in large interconnected systems. It analyses and assesses possible alternatives for optimal and innovative solutions of major frequency control issues in large interconnected systems within liberalised electricity markets. Possible improvements in the performance of frequency control are identified. A framework of frequency control ancillary services in large interconnected systems by including loads and wind generation is also proposed.The research has been motivated by the paucity of research in power system dynamics focusing on large interconnected systems such as the European synchronous system and the Eastern interconnection which experience important frequency control challenges. These challenges include:- Decline in frequency response in the Eastern interconnection - Deterministic frequency deviations observed at the top of the hours in the European synchronous systemFrequency control issues became critical when electricity markets were deregulated and frequency control became an ancillary service with a decidedly commercial focus. This commercial focus has spawned a lot of work on frequency control markets and economics whereas not much research has been devoted to dynamic simulation of large interconnected systems. Apart from this commercial focus, frequency control in large interconnected systems is still based on historical practices mainly because changes suggested in the literature can be barely applied in large interconnected systems. This is essentially because dynamic simulation studies are uncorrelated with frequency control markets and economics. More specifically, dynamic studies do not take into account the characteristics of each reserve activated and also the way the reserve is activated. With the deregulation of the electricity market, reserve is considered as a product and not necessarily a response provided by a unit. The main objectives of this research therefore are to solve critical frequency control issues in large interconnected deregulated electricity systems, which may present potential economic benefits. To achieve these objectives, frequency control in large interconnected systems is studied by considering on one hand frequency control theory and on the other hand its implementation in practice taking account of frequency control ancillary service markets as well as the economics and practical consequences of frequency control. This approach is necessary to accommodate the future evolution of frequency control in large interconnected systems. The proposed approach is illustrated through a model of frequency control in the European synchronous system, where practices are better known, are clearly standardised and also where frequency data has been obtained.

Many musicians are forced to scale down or even abandon their profession due to injuries caused by playing and practicing their instruments for long hours in unnatural body positions; also, the competition and the high standard expected of performers in the industry causes anxiety and tension in their lives. Increasingly, music schools, conservatories and colleges attempt to cater for these problems by including classes in the Alexander Technique. But young learners can also fall prey to these problems. Performance anxiety is potentially a threat to any musician’s career and can be experienced at all levels of expertise. In the light of this the following research question was tested: Is it possible to substantially reduce performance anxiety (stage fright) in instrumental playing by implementing Alexander Technique principles? The study included a group of twelve school-going children who had been identified as being prone to performance anxiety. They were divided into two groups of six each, one being the experimental group and the other the control group. The experimental group consisted of six flute students who were exposed to selected Alexander Technique principles in their lessons, while the control group consisted of six flute students that were taught by different teachers, who provided no exposure. Both groups were tested at the beginning of the research, before they played an examination, to ascertain the level of performance anxiety they experienced. Eighteen months later, after the experimental group had been exposed to Alexander principles, both groups played another examination and were then tested again to ascertain whether or not the experimental group’s levels of anxiety had been significantly reduced, compared to the control group. The control groups’ second testing was very similar to their first testing and performance anxiety was still a big drawback to their musical performance. Not only was performance anxiety markedly reduced in the experimental group, but their self-esteem and self-confidence were increased as well. As a result it was deduced that young learners can benefit tremendously from learning and applying Alexander Technique principles to the playing of a musical instrument. Copyright / Dissertation (MMus)--University of Pretoria, 2009. / Music / unrestricted

The systematic implementation of intermittent energy production sources has made the energy system more volatile and unpredictable than ever before. This development increases the importance of balancing services, in particular the primary control. However, the current research that has been conducted on the primary regulation products is limited. Specifically, the factors that drive the variation in availability and price of the primary control are unknown and the procurement is in some aspects based on perception rather than quantitative analysis. This study has investigated which these factors are and their relative significance on the availability and price of the primary control product called Frequency Containment Reserve for Normal Operation – FCR-N. The study was conducted according to methods with both qualitative and quantitative aspects to cover the complex nature of the problem from different views. The study was done in collaboration with Fortum POT at their office to gain insight and support from a market actor. Given the research questions, the result from this study is threefold. Firstly, the factors that affect the FCR-N availability have been identified and other factors have been categorised as insignificant. Secondly, the factors’ relative significances are stated to show their dependency with the FCR-N product. Lastly, an outlier case study showed how extreme situations changes the conditions for the FCR-N procurement. It has been concluded that the FCR-N price for normal operation on the Nordic electricity market can be generalised successfully through the identified parameters. It is also shown that deviations from normal operations have the possibility to create deviations in the FCR-N availability, indicating that these hours of extreme values need additional analysis in order to fully understand the available capacity. However, the significance of the researched parameters will be an indication in analysis of both the normal case and during deviations as these are the most important measures for the FCR-N availability and price.

This diploma thesis deal with analysis of current surveying methods of railway track spatial position of the track section located between Břeclav and Znojmo. At the beginning of the work there is described historical development of railway geodesy in our country and conditions of railway geodetic points field abroad. Further there are mentioned rules for measurement of railway point fields in the Czech Republic. In the following chapter you will find sub-stages of building railway point fields in track section with analysis of accuracy measurement and a proposal of prior accuracy of measurement for computing with the least square method. In the end of the thesis there is described a calculation of parameters spatial track geometry with the suggestion of computing service for uniform way of calculating partial stages of railway geodetic point field.