No description available.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 141-143).

This work treats dual-plane automatic ball balancing of elastically-mounted cylindrical rotors. The application is primarily to systems with a vertically-oriented single-bearing support, but extension is also made to horizontally-oriented single-bearing support as typically found in a vehicle wheel. The rotor elastic mounting includes three translational degrees of freedom for the body geometric center and three rotational degrees of freedom. Damping is included for each of these six degrees of freedom. The model for the automatic ball balancer consists of up to two arbitrarily-located hollow circumferential races, each of which contains up to two sliding particles. The friction model for the particles includes both viscous and Coulomb friction forces. Of considerable complexity is the logic path for the individual particles being either in motion or stationary relative to the rotor. The exact equations of motion for the overall system are derived via a Newtonian approach. Numerical-integration results show that the balancer performance depends strongly on the friction levels as well as the operating speed of the body. Simulations conducted with a pure static imbalance show that ideal automatic balancing is possible only for vertical-axis rotors that have zero Coulomb friction levels between the balancing particles and the races. Simulations with a horizontal-axis statically-imbalanced rotor show that an automatic balancer can improve performance for certain operating speeds and non-zero Coulomb friction levels in the presence of gravitational forces. Simulations conducted with a pure dynamic imbalance show that there is no inherent mechanism to counteract rotational displacements of the rotor about its geometric center. As a result, the balancing particles exhibit several phenomena described in previous works such as synchronous motion and oscillatory behaviors within their respective races. Simulations for an arbitrarily located imbalance show that rotor performance can be improved using dual-plane balancing techniques for certain operating speeds and Coulomb friction levels. Due to the inherent complexity in eliminating an arbitrarily located mass imbalance, the system is generally unable to reach a perfectly balanced configuration, but performance can be improved for carefully-selected initial conditions. / Ph. D.

The production and consumption of electricity on the power grid has to balance at all times. Slow balancing, over days and weeks, is governed by the electricity market and carried out through production planning.  Fast balancing, within the operational hour, is carried out by hydropower plants operating in frequency control mode. The need of balancing power is expected to increase as more varying renewable energy production is connected to the grid, and the deregulated electricity market presents a challenge to the frequency control of the grid. The first part of this thesis suggests a method to quantify the need for balancing or energy storage induced by varying renewable energy sources. It is found that for high shares of wind and solar power in the system, the energy storage need over a two-week horizon is almost 20% of the production. The second and third part of the thesis focus on frequency control. In the second part, measurements from three Swedish hydropower plants are compared with the behaviour expected from commonly used power system analysis hydropower models. It is found that backlash in the guide vane and runner regulating mechanisms has a large impact on the frequency control performance of the plants. In the third part of the thesis, the parameters of the primary frequency control in the Nordic grid are optimised with respect to performance, robustness and actuator work. It is found that retuning of the controller parameters can improve the performance and robustness, with a reasonable increase of the actuator work. A floating deadband in the controller is also discussed as a means to improve performance without increasing the actuator work.

No description available.

Thesis (M.S.)--Oregon State University, 1971. / Typescript (photocopy). Includes bibliographical references. Also available online.

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Battery pack imbalance is one of the most pressing issues for companies involved in Battery Energy Storage. The importance of Battery Balancing with respect to Xtreme Power has been analysed in detail. Various methods of Battery Balancing have been researched and presented. Methods that were the most suitable to Xtreme Power's battery pack topology were selected and tested. The results of these experiments are presented and relevant conclusions are shown. / text

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Massively multiplayer games allow hundreds of players to play and interact with each other simultaneously. Due to the increasing need to provide a greater degree of interaction to more players, load balancing is critical on the servers that host the game. A common approach is to divide the world into microcells (small regions of the game terrain) and to allocate the microcells dynamically across multiple servers. We describe a visibility--based technique that guides the creation of microcells and their dynamic allocation. This technique is designed to reduce the amount of cross--server communication, in the hope of providing better load balancing than other load--balancing strategies. We hypothesize that reduction in expensive cross-server traffic will reduce the overall load on the system. We employ horizon counts map to create visibility based microcells, in order to emphasize primary occluders in the terrain. In our testing we consider traffic over a given quality of service threshold as the primary metric for minimization. As result of our testing we find that dynamic load balancing produces significant improvement in the frequency of quality of service failures. We find that our visibility-based micro cells do not outperform basic rectangular microcells discussed in earlier research. We also find that cross-server traffic makes up a much smaller portion of overall message load than we had anticipated, reducing the potential overall benefit from cross server message optimisation. / Thesis (Master, Computing) -- Queen's University, 2011-09-28 14:15:32.173