M.Ing. (Electrical and Electronic Engineering) / Long transmission lines in power system require high line loading in order to lower voltage limits due to line losses. For relatively long lines, line charging is high and thus higher voltage limits reached at low loading. It follows then that it is a challenge to maintaining the voltages between the acceptable limits for relatively long lines. This dissertation highlights the problems experienced when load varying from very low to very high is supplied by very long parallel lines of different impedance characteristic. When the load is extremely high, there are low voltages experienced which are solved by use of shunt capacitors and/or adding more lines. When the load is extremely low, there are high voltages experienced which are solved by use of shunt reactors and/or switching some of the lines off. The type of solutions to this two loading extremes as indicated above, can be problematic, in that; new lines requires servitudes which can take too long, shunt capacitors and reactors in this type of the network is not desirable since the introduction of too many of these devices have maintenance implications and they would require continuous switching to maintain acceptable voltages, resulting in complicated operation of the network. This research proposes the use of a phase shifting transformer located on one of two parallel corridors supplying power to a load located remotely from the rest of the system. The transformer is able to rearrange the active power flows to vary loadings of the corridors and the improvements in voltage regulation can be realised during both low and high load conditions.

This dissertation addresses the problem of optimally scheduling the hoists of a twin rock winder system in a demand side management context. The objective is to schedule the hoists at minimum energy cost taking into account various physical and operational constraints and production requirements as well as unplanned system delays. The problem is solved by first developing a static linear programming model of the rock winder system. The model is built on a discrete dynamic winder model and consists of physical and operational winder system constraints and an energy cost based objective function. Secondly a model predictive control based scheduling algorithm is applied to the model to provide closed-loop feedback control. The scheduling algorithm first solves the linear programming problem before applying an adapted branch and bound integer solution methodology to obtain a near optimal integer schedule solution. The scheduling algorithm also compensates for situations resulting in infeasible linear programming solutions. The simulation results show the model predictive control based scheduling algorithm to be able to successfully generate hoist schedules that result in steady state solutions in all scenarios studied, including where delays are enforced. The energy cost objective function is proven to be very effective in ensuring minimal hoisting during expensive peak periods and maximum hoisting during low energy cost off-peak periods. The algorithm also ensures that the hoist target is achieved while controlling all system states within or around their boundaries for a sustainable and continuous hoist schedule. Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / Unrestricted

The following master thesis is focused on creation of methodology for optimal usage of load balancing in data center environment. Thesis is divided into eight chapters. The first chapter describes the reasons why to deal with this topic further. The second chapter summarizes the state of load balancing. This chapter is based on research of already elaborated thesis which were focused on load balancing in different ways. The third chapter summarizes load balancing including its key principles. The fourth chapter describes an actual state of load balancing in data center environment. An observation of real usage of load balancing in selected data center was used for the main purpose of this chapter. The fifth chapter consists of analysis of the currently existing methodologies which are used from the infrastructure projects purpose. The sixth chapter deals with creation of methodology for optimal usage of load balancing in data center. The seventh chapter evaluates usage of methodology by applying of this methodology to real practical example of implementation of load balancing. The eighth chapter summarizes all detected conclusions.

L’analyse de flux de données est utilisée dans beaucoup de contexte où la masse des données et/ou le débit auquel elles sont générées, excluent d’autres approches (par exemple le traitement par lots). Le modèle flux fourni des solutions aléatoires et/ou fondées sur des approximations pour calculer des fonctions d’intérêt sur des flux (repartis) de n-uplets, en considérant le pire cas, et en essayant de minimiser l’utilisation des ressources. En particulier, nous nous intéressons à deux problèmes classiques : l’estimation de fréquence et les poids lourds. Un champ d’application moins courant est le traitement de flux qui est d’une certaine façon un champ complémentaire aux modèle flux. Celui-ci fournis des systèmes pour effectuer des calculs génériques sur les flux en temps réel souple, qui passent à l’échèle. Cette dualité nous permet d’appliquer des solutions du modèle flux pour optimiser des systèmes de traitement de flux. Dans cette thèse, nous proposons un nouvel algorithme pour la détection d’éléments surabondants dans des flux repartis, ainsi que deux extensions d’un algorithme classique pour l’estimation des fréquences des items. Nous nous intéressons également à deux problèmes : construire un partitionnement équitable de l’univers des n-uplets par rapport à leurs poids et l’estimation des valeurs de ces n-uplets. Nous utilisons ces algorithmes pour équilibrer et/ou délester la charge dans les systèmes de traitement de flux. / Nowadays stream analysis is used in many context where the amount of data and/or the rate at which it is generated rules out other approaches (e.g., batch processing). The data streaming model provides randomized and/or approximated solutions to compute specific functions over (distributed) stream(s) of data-items in worst case scenarios, while striving for small resources usage. In particular, we look into two classical and related data streaming problems: frequency estimation and (distributed) heavy hitters. A less common field of application is stream processing which is somehow complementary and more practical, providing efficient and highly scalable frameworks to perform soft real-time generic computation on streams, relying on cloud computing. This duality allows us to apply data streaming solutions to optimize stream processing systems. In this thesis, we provide a novel algorithm to track heavy hitters in distributed streams and two extensions of a well-known algorithm to estimate the frequencies of data items. We also tackle two related problems and their solution: provide even partitioning of the item universe based on their weights and provide an estimation of the values carried by the items of the stream. We then apply these results to both network monitoring and stream processing. In particular, we leverage these solutions to perform load shedding as well as to load balance parallelized operators in stream processing systems.

D.Phil / The prediction of the expected transmission network loads as required for transmission network power flow studies, has become very important and much more complex than ten to twenty years ago. Therefore a single forecast is no longer the answer to the problem. The modelling of different long-term electrical forecasts makes it possible to compare a number of different forecasts. The modelling provides the further option that each expected load can be entered as a range and then the developed balancing algorithm checks for consensus (feasibility). If feasibility exists, then the different forecasts are reconciled (a feasible solution is determined). Factors such as international and national market trends, economical cycles, different weather patterns, climate cycles and demographic changes are studied. The factors that have significant impact on the transmission electrical loads are integrated in ten different forecasts. It thus gives more insight into the electrical industry and makes the forecast results more informative and therefore reduces the uncertainty in the future expected loads.

The impact of eliminating extraneous sound and light on students’ achievement was investigated under four conditions: Light and Sound controlled, Sound Only controlled, Light Only controlled and neither Light nor Sound controlled. Group, age and gender were the control variables. Four randomly selected groups of high school freshmen students with different backgrounds were the participants in this study. Academic achievement was the dependent variable measured on a pretest, a posttest and a post-posttest, each separated by an interval of 15 days. ANOVA was used to test the various hypotheses related to the impact of eliminating sound and light on student learning. Independent sample T tests on the effect of gender indicated a significant effect while age was non- significant. Follow up analysis indicated that sound and light are not potential sources of extraneous load when tested individually.

Morgongåva is an urban centre in Sweden, with several challenges in the electrical power grid. In order to use the power grid more efficiently, this report investigates potentials of installing a battery energy storage system (BESS). Focus lies on finding economic and technical benefits of reducing power peaks, which occur during high demand hours when transmitting energy is more expensive. This method is referred to as peak shaving. Further, economic calculations if installing a BESS are based on electricity pricing data. Calculations regarding technical benefits are based on net power demand data. Further, the study shows that the usage of the grid, which was measured with the load factor, would increase and thus allow installation of more power sources and connecting more load to the grid. The load factor was estimated to increase by an average of 2.12 percent each month in 2019. In one year, the economic profit was estimated to be 91,000 kr. The conclusion is that there are economic profits for Sala-Heby Energi of installing a BESS, but more importantly a BESS has technical consequences in the power grid. Where technical benefits are important in order to reach the goals of Agenda 2030 but also to obtain a more reliable grid for the customers. A sensitivity analysis shows that the model is robust. Thus, the conclusion is that Sala-Heby Energi and the local electricity grid in Morgongåva would benefit from installing a BESS.

abstract: Sedentary behavior and excessive weight gain have been proven to deteriorate many characteristics of muscle. Low muscular power and mass with excess fat mass are risk factors for a multitude of chronic conditions and functional disabilities. Resistance training (RT) has long been accepted as a rehabilitative method of maintaining or enhancing muscular performance and composition. There are various methods of determining lower extremity muscular power; however, isokinetic dynamometry has emerged as one of the most accurate and reliable methods in clinical and research settings. Likewise, various methods exist for determining muscle thickness; however, many of those methods are expensive and can expose individuals to radiation. Ultrasonography has emerged as an accurate and reliable alternative to measuring lower extremity muscle thickness. The objective of this study was to assess the effects of high-load/low-volume (HLLV) and low-load/high-volume (LLHV) RT on isokinetic knee extensor and flexor peak power in sedentary, RT naïve, overweight or obese men and women (Body Mass Index ≥ 25 kg/m2). Twenty-one subjects (n = 21) completed this study and were randomized into one of the following groups: control, a HLLV group that performed three sets of 5 repetitions for all exercises until volitional fatigue, and LLHV which performed three sets of 15 repetitions for all exercises until volitional fatigue. Subjects randomized to the RT groups performed full-body exercises routines on three non-consecutive days per week. Changes in isokinetic knee extensor and flexor peak power, quadriceps ultrasound muscle thickness, and right leg segment of dual-energy X-ray absorptiometry (DEXA) scans were measured before and after the 12-week RT intervention. There were no significant differences found in group, time or, group by time interactions for knee extensor and flexor peak power using isokinetic dynamometry. Other than a group interaction for vastus intermedius muscle thickness (P=0.008), no significant interactions or differences were observed for any of the other variables tested. Based on the results of this study, neither high- nor low-load RT resulted in significant differences between intervention groups in peak power of the knee extensors and flexor, muscle thickness changes of the vastus intermedius, and vastus lateralis and, in the right lower extremity segmented body composition measures using DEXA. / Dissertation/Thesis / Masters Thesis Exercise and Wellness 2020

Master thesis is focused on signalling analysis of third-generation mobile network UMTS. In first part of master thesis is described a question of standard IMT-2000, introduces the principles of the WCDMA air interface, gives a wide overview of the UMTS system architecture and signal processing. In second part of master thesis is described a question of signalling analysis, including general protocol model for UTRAN terrestrial interfaces. This chapter is focused on elementary procedures, Radio Resource Management procedure examples, Mobility Management procedure examples and Call Control procedure examples in the first place. Last chapter of master thesis is focused on radio network planning of UMTS with practical location of basic station Node-B.

This diploma thesis is focused on synthetic loads, especially electronically controlled loads. The thesis analyse principles of mechanically and electronically controlled loads and theirs operation modes. The paper also carried out a search of AC loads available on the market. The parameters of the AC load were based on the requirements provided by client. The functionality of the designed load is verified by simulation. The thesis continues with realization of the designed schematics and bringing the load to function. At the last section of the thesis are detail parameters of the designed load verified by measurement.