The continuous escalation of intermittent energy added to the grid and forecasts of peaking power demand increments are rising the effort spent for evaluating the economic feasibility of energy storages. The aim of this research is the techno-economic analysis of Compressed Air Energy Storage (CAES) systems, capable of storing large quantities of off-peak electric energy in the form of high-pressure air, as an ―energy stock‖ which allows the production of high-profit on-peak electricity when required by the grid. Several studies of both conventional and innovative adiabatic concepts are carried out in order to identify and improve the parameters that mostly affect the plant performances. Technical models, that consider the effect of time, are developed to evaluate the parameters that reduce the electric energy spent for compressing the air and that maximize the electric energy produced. In the conventional plant, particular attention is put on the understanding of the effects of air storage pressure range, recuperator, reheating and Turbine Inlet Temperature. For the adiabatic instead, a thorough analysis of the challenging Thermal Energy Storage (TES) is performed for understanding the advantages and drawbacks of this novel efficient concept of CAES. In a further step the economic analyses are aimed at evaluating the different configurations proposed in the technical investigation and the effects that variations of generation train and storage characteristics have on the profitability. After an analysis of the TES impact on the profits, a final comparison is carried out against two existing technologies: Pumped Hydro Energy Storage and gas turbine. The results of these studies confirm, from a technical and economic point of view, the reasons of the growing interest toward CAES as a feasible solution to manage the intermittent energy production. In particular they underline the conventional CAES as promising technology to undertake.

In recent years, fuel assembly bow in Ringhals 3 has started to increase again after lower levels of bow. Normally, the fuel assemblies are straight axially. One of the consequences of fuel assembly bow is perturbed power distribution across the core, resulting in smaller margins of safety during operation. A way of ensuring safe operation is add-on margins, penalties, dependent on bow amplitude, added to the power peaking factors. A new method of producing these penalties, based on realistic water gap distribution derived from measurements, was used. By comparing the new penalties with the currently used penalties, the currently used penalties were concluded to be around 10 percent smaller for both FdH, the radial power peaking factor penalty, and FQ, the local power peaking factor penalty. The currently used penalties hence are significantly lower. However, the conclusion should be seen as an indication, rather than directly implementable, since there is potential to evolve the method further and eliminate sources of error.

One of two project reports: The other part is designated Part B: On-Campus Project / <p> Computer studies are made of a CANDU-PHW reactor core containing an annulus of enriched uranium around a central zone of natural uranium. For hybrid cores of this type with a maximum radial form factor, the uranium requirements, fuel costs, stability, and power peaking upon refuelling are investigated. It is found that these hybrid cores offer potential savings of 10% to 20% in fuel costs and uranium utilization compared to the present CANDU-PHW core, and are only slightly less stable. However, power peaking upon refuelling is a problem with these cores.</p> / Thesis / Master of Engineering (ME)

The purpose of this thesis was to observe psychological, physiological, and performance changes to determine when two high-level weightlifters were peaked for a major competition. We addressed this purpose by conducting a two-part case study series with one USA international level female and one USA national level male weightlifter. Both athletes were considered to be peaked on competition day. The results support our hypothesis that jumping performance would be peaked on competition day corresponding with an increased recovery and decreased stress state. However, contrary to our hypothesis, each athlete exhibited small decreases in muscle size leading into the competition relative to baseline values. Further, changes in inflammatory markers were inconsistent for each athlete and were not reduced as hypothesized. Based on our findings, this investigation supports the use of overreaching and tapering for individual strength-power athletes providing insight into underlying psychological and physiological basis for observed changes in performance.

No description available.

The increasing demand for high data rate devices and many applications in short range high speed communication, attract many RF IC designers to work on 24-GHz transceiver design. The Federal Communication Commission (FCC) also dedicates the unlicensed 24-GHz band for industrial, science, and medical applications to overcome the interference in overcrowded communications and have higher output signal power. LNA is the first building of the receiver and is a very critical building block for the overall receiver performance. The total NF and sensitivity of the receiver mainly depends on the LNAs NF that mandates a very low NF LNA design. Depending on its gain, the noise figure of the next stages can relax. However, the high gain of an LNA enforces the next stages to be more linear since they suffer from larger signal at their input stage and can get saturated easily. Apparently, designing high gain, low noise, and highly linear LNA is very stimulating. In this thesis, a wideband LNA with low noise figure and high linearity has been designed in 8XP 0.13-um SiGe BiCMOS IBM technology. The highlight of this design is proposing the peaking technique, which results in considerable linearity improvement. Loading the LNA with class AB amplifier, power gain experiences a peaking in high input signal swing levels. The next stager after the LNA is the buffer to provide isolation between the LNA and mixer, and also avoid loading of the LNA from the mixer. Instead of using popular emitter follower architecture, another circuit is proposed to have higher gain and linearity. This buffer has two separate out of phase inputs, coming from the LNA and are combined constructively at the output of the buffer. Since the frequency of this design is high, electromagnetic (EM) simulation for pads, interconnects, transmission lines, inductors, and coplanar transmission lines has been completed using Sonnet cad tool to consider all the parasitic and coupling effects. Considering all the EM effects, the LNA has 15 dB gain with 2.9 dB NF and -8.8 dBm input 1-dB compression point. The designed LNA is wideband, covering the frequency range of 12-GHz to 31-GHz. However, the designed LNA, has the capability of having higher gain at the expense of lower linearity and narrower frequency band using different control voltage. As an example peak gain of 29.3 dB at the 3-dB frequency range of 23.8 to 25.8-GHz can be achieved, having 2.3 dB noise figure and -17 dBm linearity. / Master of Science

Traditional implementations of optical receivers are designed to operate with external photodetectors or require integration in a hybrid technology. By integrating a CMOS photodetector monolithically with an optical receiver, it can lead to the advantage of speed performance and cost. This dissertation describes the implementation of a photodetector in CMOS technology and the design of an optical receiver front-end and a clock and data recovery system. The CMOS detector converts the light input into an electrical signal, which is then amplified by the receiver front-end. The recovery system subsequently processes the amplified signal to extract the clock signal and retime the data. An inductive peaking methodology has been used extensively in the front-end. It allows the accomplishment of a necessary gain to compensate for an underperformed responsivity from the photodetector. The recovery circuits based on a nonlinear circuit technique were designed to detect the timing information contained in the data input. The clock and data recovery system consists of two units viz. a frequency-locked loop and a phase-locked loop. The frequency-locked loop adjusts the oscillator’s frequency to the vicinity of data rate before phase locking takes place. The phase-locked loop detects the relative locations between the data transition and the clock edge. It then synchronises the input data to the clock signal generated by the oscillator. A system level simulation was performed and it was found to function correctly and to comply with the gigabit fibre channel specification. / Dissertation (MEng (Micro-Electronics))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

Plants rely on diverse strategies to regulate water loss during drought. The phytohormone abscisic acid (ABA) is a critical mediator of stomatal closure during water stress in seed plants. Studies in conifers identified diverging strategies in long-term drought of ABA-mediated dynamics, particularly a peaking type dynamic during long term drought in some conifers. Few studies have reported this dynamic in angiosperms, and no study has revealed the mechanism driving declines in ABA levels as drought progresses in peaking type species. To understand peaking type dynamics, we exposed the model peaking type gymnosperm species <i>Callitris rhomboidea</i> and the highly drought resistant evergreen angiosperm <i>Umbellularia californica</i> to controlled long-term drought. We measured leaf water potentials (Ψ_l), stomatal conductance, ABA and the ABA catabolite phaseic acid (PA) levels in potted plants during a prolonged but non-fatal drought. We aimed to determine which of three potential drivers of peaking type dynamic were responsible for this response: (1) increased catabolism of ABA into PA at a threshold Ψ_l , (2) ABA export from the leaf is enhanced under drought, and (3) ABA biosynthesis ceases at a threshold Ψ_l. During long term drought, the evergreen angiosperm species <i>U. californica</i> demonstrated peaking type ABA dynamics like gymnosperms. In both species, PA levels did not increase significantly, in fact, PA levels tracked ABA levels, suggesting that ABA catabolism to PA may be a function of ABA levels. Girdling experiments to determine whether export from the leaf drove declines in ABA levels demonstrated that of the majority of ABA was likely converted to ABA glucose ester (ABA-GE), an inactive storage form of ABA, and exported from shoots during drought. Finally, by rapidly dehydrating branched collected at different timepoints during long-term drought we were able to determine that ABA biosynthesis is completely down regulated in leaves that have been dehydrated beyond leaf turgor loss point. The decline in ABA levels in peaking type species appears conserved across seed plants and is mediated by high export rates in the form of ABA-GE. Future work should assess a more diverse selection of species as well as study long-term drought in less tolerant species to test whether ABA biosynthesis is deactivated in all species once Ψ_ldeclines below turgor loss point.

The conversion of audio from the digital to analog domain has the potential to result in distortion due to converter overload. This occurs because some peaks in the signal cannot be defined digitally and only become problematic during the conversion into the analog domain, exceeding the level that can be represented by the converter, causing it to overload. Although True Peak limiting and metering can prevent and monitor this issue, some professional mastering engineers choose not to do so. The study tested claims made against overload prevention, including the adequacy of headroom in modern D/A converters and the inaudibility of the distortion caused by overload. Preference was also added to the audibility claim. Measurements show that there is not enough headroom in modern D/A converters to avoid overload, but the distortion created by overload is generally inaudible in an uncompressed WAVE format hard rock song. Additionally, there is no clear preference. The measurements found that overload only occurs when the device's volume is raised to its maximum output.

The global electricity generation industry is very reliant on the use of fossil fuels, particularly natural gas and coal. However, it is quickly becoming a reality that the over-consumption of these resources will continue to lead to significant global damage via global warming, ecosystem destruction, and the depletion of these so-called non-renewable re-sources. To combat this issue, renewable sources such as wind, biofuels and solar are be-coming much more prevalent in the power generation industry, but significant economic, reliability and availability barriers to entry will prevent these sources from being major contributors to the power industry for decades. To this end, this thesis focuses on the design, operation, optimization and life cycle analysis of an integrated solid-oxide fuel (SOFC) cell power plant integrated with com-pressed air energy storage (CAES). This plant, fueled by either natural gas or coal, can make much more efficient use of their limited non-renewable fuel sources, and are capable of achieving nearly 100% carbon capture at the plant boundary. This plant is intended to serve as a more efficient and environmentally responsible alternative to current power generation methods while still exploiting remaining fossil fuels to their fullest extent. This thesis details the design, sizing and simulation of integrated SOFC/CAES plants in Aspen Plus so that full feasibility and techno-economic analyses may be performed, the results of which are then compared to the current state-of-the-art (SOTA) options. In order to compare the plants on an environmental level, full cradle-to-grave life-cycle analyses using the ReCiPe 2008 method are completed for each SOFC-based plant and all comparable SOTA options under a wide range of assumptions and plant configurations, such as the use of carbon capture strategies. Furthermore, detailed reduced-order dynamic models of the integrated SOFC/CAES plants are developed and simulated with a newly developed rolling-horizon optimization method to assess the load-following capabilities of the integrated plant. Real scaled demand data for the market of Ontario, Canada for the years 2013 and 2014 are used as the demand data for the simulations. This thesis takes strides in proving the feasibility of an integrated SOFC/CAES power plant for providing clean, efficient, reliable and cost-effective power using fossil fuels. The next steps for this project involve the development of a lab-scale pilot plant, which would be used to validate simulation results and provide an opportunity for the real-time application and assessment of the potential of this plant design. / Thesis / Doctor of Philosophy (PhD)