The purpose of this study is to determine the effectiveness of an in-season resistance training program on improving measures of strength in female collegiate triathletes. Nine females (age = 19.2 ± 1.1 years, height = 166.5 ± 12.5 cm, body mass = 61.1 ± 9 kg) with limited resistance training experience were examined for this study. Formal RT intervention was monitored for 7 weeks with the athletes being assigned 6 weeks of independent RT prior to the pre-test. Athletes completed a standardized athlete monitoring program pre and post resistance training intervention. Paired sample t-tests were used to determine differences between conditions with Cohen’s d effect sizes describing the magnitude of change between pre and post-intervention. No significant changes were found between the two testing sessions (p > 0.05). A longer duration of utilizing resistance training adhering to a phase potentiated approach may be necessary for significant changes to occur.

The thesis deals with analysis of factors contributing to the development of ephemeral gully erosion on area of the Czech Republic. Method used to direct measurements of ephemeral gully erosion was developed. The statistical sample of gullies was measured to describe the characteristics of ephemeral gullies. Statistical methods were used to compute simple and multiple linear regression models. The models describe relationships between ephemeral gully parameters or factors contributing to development of ephemeral gully. The thesis is concentrated with the development of methodology for prediction the occurrence and prediction of parameters of ephemeral gullies. The methodology can be used to design the optimal erosion control measures in the conditions of the Czech Republic.

The subject matter of the thesis is the identification of concentrated runoff waterways in the landscape and their consequent stabilization. The municipalities of Čejkovice and Mutěnice in the South Moravian region were analysed in order to reach this purpose. The thesis introduces theoretical bases for the definition of concentrated runoff waterways and their application in the calculation. The area was analysed on the basis of the digital elevation model in ArcGIS software environment. The CN curves method by means of the hydrological model DesQ – MAX Q was used for the calculation of concentrated runoff waterways.

Direct absorption solar collectors offer possible improvement in efficiency over traditional surface absorbing collectors, because they have fewer heat transfer steps and has the ability to utilise higher radiation fluxes. Carbon black based nanofluids, in a base fluid of salt water, were synthesised by a two-step method where the carbon black nanoparticles were treated with a surfactant, TWEEN-20, in a 1:2 mass ratio and sonicated for 60 minutes to break up agglomerates. The synthesised nanofluids showed stability for over 31 days. The different carbon black concentration nanofluids' solar irradiation absorption properties were compared with each other and with the base fluid of salt water in a concentrating, as well as non-concentration scenario. It was found that the carbon black nanofluids showed excellent absorption properties over the entire solar radiation spectrum. A 1 m2 concentrating unit using a two-axis tracking system, with two mirrors and a 1 m diameter circular Fresnel lens, was used to concentrate solar radiation on a direct absorption solar collector flow cell with a 10 cm2 collection area. An optimum concentration of 0.001 volume % carbon black was found to show a 42 % increase in heating rate, compared to that of salt water. The collector was, however, hampered by high energy losses and the maximum collector efficiency achieved was only 46 %, 23 % higher than that of salt water. The overall system efficiency was only 22 %. This low efficiency can be attributed to the high optical concentration losses (50 % - 70 %) present in the concentrating unit. / Dissertation (MEng)--University of Pretoria, 2016. / Chemical Engineering / MEng / Unrestricted

The durability of two solar-selective aluminium titanium oxynitride multilayer coatings was studied under conditions simulating realistic operation of central receiver power plants. The coatings were deposited by cathodic vacuum arc applying an optimized design concept for complete solar-selective coating (SSC) stacks. Compositional, structural and optical characterization of initial and final stacks was performed by scanning electron microscopy, elastic recoil detection, UV-Vis-NIR-IR spectrophotometry and X-Ray diffraction. The design concept of the solar selective coatings was validated by an excellent agreement between simulated and initial experimental stacking order, composition and optical properties. Both SSC stacks were stable in single stage tests of 12 hours at 650°C. At 800°C, they underwent a structural transformation by full oxidation and they lost their solar selectivity. During cyclic durability tests, multilayer 1, comprised of TiN, Al0.64Ti0.36N and an Al1.37Ti0.54O top layer, fulfilled the performance criterion (PC) ≤ 5% for 300 symmetric, 3 hours long cycles at 600°C in air. Multilayer 2, which was constituted of four AlyTi1-y(OxN1-x) layers, met the performance criterion for 250 cycles (750 hours), but was more sensitive to these harsh conditions. With regard to the degradation mechanisms, the coarser microstructure of multilayer 1 is more resistant against oxidation than multilayer 2 with its graded oxygen content. These results confirm that the designed SSCs based on AlyTi1-y(OxN1-x) materials withstand breakdown at 600ºC in air. Therefore, they can be an exciting candidate material for concentrated solar power applications at high temperature.

The transparent conductive oxide (TCO) SnO2:Ta is developed as a selectively solar-transmitting coating for concentrated solar power (CSP) absorbers. Upon covering with an antireflective layer, a calculated absorptivity of 95% and an emissivity of 30% are achieved for the model configuration of SnO2:Ta on top of a perfect black body (BB). High-temperature stability of the developed TCO up to 1073 K is shown in situ by spectroscopic ellipsometry and Rutherford backscattering spectrometry. The universality of the concept is demonstrated by transforming silicon and glassy carbon from non-selective into solar-selective absorbers by depositing the TCO on top of them. Finally, the energy conversion efficiencies of SnO2:Ta on top of a BB and an ideal non-selective BB absorber are extensively compared as a function of solar concentration factor C and absorber temperature TH. Equal CSP efficiencies can be achieved by the TCO on BB configuration with approximately 50% lower solar concentration. This improvement could be used to reduce the number of mirrors in a solar plant, and thus, the levelized costs of electricity for CSP technology.

>Magister Scientiae - MSc / Phase change material (PCM) through latent heat of molten salt, is a convincing way for thermal energy storage in CSP applications due to its high volume density. Molten salt, with (60% NaNO3 and 40% KNO3) has been used extensively for energy storage however; the low thermal conductivity and specific heat have limited its large implementation in solar applications. For that, molten salt with the additive of silver nanowires (AgNWs) was synthesized and characterized. This research project aims to investigate the thermophysical properties enhancement of nanosalt (Mixture of molten salt and silver nanowires). The results obtained showed that by simply adjusting the temperature, Silver nanowires with high aspect ratio have been synthesized through the enhanced PVP polyol process method. SEM results revealed a network of silver nanowires and TEM results confirmed the presence of silver nanowires with an average diameter of 129 nm and 16 μm in length.

<p>Photovoltaic (PV) cells have become an increasingly ubiquitous technology; however, concentrating photovoltaics (CPV), despite their higher theoretical efficiencies and lower costs, have seen much more limited adoption. Recent literature indicates that thermal management is a key challenge in CPV systems. If not addressed, it can negatively impact efficiency and reliability (lifetime). Traditional cooling methods for CPV use heat sinks, forced air convection or liquid cooling, which can induce an extremely large convection area, or parasite electric consumption. In addition, the moving parts in cooling system usually result in a shorter life time and higher expense for maintenance. Therefore, there is a need for an improved cooling technology that enables significant improvement in CPV systems. As a passive and compact cooling mechanism, radiative cooling utilizes the transparency window of the atmosphere in the long wavelength infrared. It enables direct heat exchange between objects on earth’s surface with outer space. Since radiated power is proportional to the difference of the fourth powers of the temperatures of PV and ambient, significantly greater cooling powers can be realized at high temperatures, compared with convection and conduction. These qualities make radiative cooling a promising method for thermal management of CPV. In this work, experiments show that a temperature drop of 36 degree C have been achieved by radiative cooling, which results in an increase of 0.8 V for open-circuit voltage of GaSb solar cell. The corresponding simulations also reveal the physics behind radiative cooling and give a thorough analysis of the cooling performance.</p>

This master thesis report presents a prefeasibility analysis for a Saudi Company to enter the solar industry.Section one of this report illustrates the value chain analysis and opportunity identification and evaluation process applied to CSP technology. Section two offers an example of a potential business case in hybrid-powered commercial irrigation.

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