7 pp. / Forage sorghum is commonly grown in Arizona for silage for dairy cattle and is valued for its lower nitrogen fertilizer and water requirements compared to corn. Five forage sorghum hybrids were evaluated in a study conducted at the Maricopa Agricultural Center in 2015. The hybrids tested did not differ in yield or overall feeding quality (TDN, total digestible nutrients) although some differences in heading, plant height, moisture content, and some specific quality parameters were detected.

Drilling is an industrial process in which holes are produced by removal of material. This process is relatively well established for macroscale machining. However, microscale mechanical drilling is a more challenging process, especially in parts made of difficult-to-cut materials such as nickel-based superalloys. Although laser drilling and electrical discharge machining (EDM) have been reported as alternatives, mechanical drilling continues to be widely used for industrial macroscale drilling. However, mechanical microdrilling suffers from premature drill breakage due to the fragile nature of the microdrill. Furthermore, mechanical-drilled holes are inherently associated with geometry and metallurgy defects such as burr and subsurface damage, respectively. In laser percussion drilling, the challenge is how to improve the quality of the hole by minimising taper, recast layer, and heat affected zone formation. In addition, drilling hollow parts such as airfoil blades without introducing damage to the back wall is a major challenge in laser drilling. In drilling, the accuracy of the process and the quality of the surface finish are of great importance for both the manufacturer and the customer. Hybrid machining has been identified as a promising process which combines the benefits of different machining processes especially when applied to machining of superalloys. This Thesis presents a novel method to microdrill an Inconel 718 alloy, at both normal and inclined angles to the surface, using laser followed by mechanical drilling (sequential drilling). The method was aimed at extending the twist drill life and improving the quality of the hole when compared with existing techniques. The effect of laser predrilled-hole geometry on the quality of the produced hole were studied and evaluated. Continuous wave (CW) fibre and pulsed Nd:YAG lasers were used to produce holes with different geometry (blind, positive and negative tapered holes) as a pilot hole for mechanical drilling. CW fibre and Nd:YAG laser microdrilling of Inconel 718 alloy were implemented and evaluated before conducting the sequential drilling process. Taguchi methods were employed to design the experiments and analyse the results to establish the optimum set of parameters that yields an acceptable level of the response target. The standard commercial statistical software package MINITAB was used to evaluate the results. Initial experiments on the use of CW fibre laser drilling showed a great improvement in the quality of the hole and drilling speed. Those encouraging results inspired more experimental work and further evaluation of microdrilling of an Inconel 718 alloy. This unprecedented work was aimed at establishing the optimum conditions of laser and process parameters for hole taper, recast layer, and machining time. The results proved that the CW fibre laser drilling mechanism could be considered as a keyhole laser welding before material breakthrough. Furthermore, the process gas must be used to push away the molten material through the hole exit. The results also showed that a near zero tapered hole with very small recast layer and free of micro-cracks could be achieved with air process gas. This would have huge economical and environmental impacts since air is cheap and also an abundant resource. In the case of Nd:YAG laser microdrilling, the results proved that using assisted gas in laser drilling would not always increase the drilling speed or improve the quality of the hole. It was also found that the quality of the holes produced by air process gas is sufficient to meet the requirements for mechanical finishing. The sequential laser mechanical technique reduced the width of cut compared to mechanical drilling and relieved the load on the drill point resulting in a decrease in the thermal and mechanical stresses on the cutting tool. When compared with pure mechanical microdrilling, mechanical finishing of near zero laser drilled hole resulted in 100-330% increase in the tool life, up to 75% reduction in burr height, and significant improvement in surface integrity. In addition, the sequential laser and mechanical drilling of laser blind holes would be an effective technique for decreasing burr size and avoiding the back-wall problem in laser drilling of hollow parts especially when the exit surface of the components to be drilled has a closed cavity or is hard to access. It was also found that a smaller predrilled hole provided stability to the twist drill at the entry stage. However, burr size at the exit side decreased when the size of the predrilled hole was increased. Therefore, the mechanical finishing of negative tapered hole technique was developed to maintain the stability of the drill, extend the drill life, improve the burr size and surface integrity. The burr size for the mechanical finishing of negatively tapered laser predrilled holes was measured to be 6 times smaller than that of pure mechanical drilling. Finally, the results proved that the new technique alleviated the indentation and secondary cutting edge action. This would enable manufacturers to grind drills to thicker web thickness, which in turn, will increase the drill strength.

The prediction of the performance of hybrid plants as production material is complicated by the genetic structure of the hybrid population. Fundamental quantitative genetic concepts are defined with respect to disomic, randomly fertilized populations which are in linkage and Hardy-Weinberg equilibrium. Hybrid populations of crosses are, however, in disequilibrium and do not meet these assumptions of quantitative genetic theory. The theory of inheritance in hybrid populations has not been fully developed and the complex models that have been developed have not reached a stage where they have been implemented to adapt selection practices for hybrid populations. Therefore in practice hybrids are often selected using selection methodology that has been developed for pure species despite large differences in the underlying genetic properties of the populations. It is not known to which extent such selections are able to predict the performance of progeny or clones in hybrid populations. This study was based on historical data and investigated the efficiency of BLUP in hybrid populations. As a case study the selection of ortets in three hybrid Eucalyptus populations was investigated. Ortet selection in E. grandis × E. saligna, E. grandis × E. urophyllaand E. grandis × E. camaldulensis populations was compared with selection in E. grandis populations. Clonal performance was predicted from a series of hybrid family trials whereas realised clonal performance was assessed in clonal trials. The predicted and realised clonal performances were correlated to assess the efficiency of the predictions. A series of constructed indices was created that placed a range of weights on family versus individual tree performances to obtain an indication of the range of correlations that could be expected from the data. Different BLUP methods were compared including selection for breeding and various forward selections for clonal forestry (“clonal forward selection”). The clonal forward selections were based on different estimates of the proportion of total genetic variance that is ascribed to non-additive genetic variance. The results of the study indicated that there were no observable differences in the efficiency of the BLUP predictions in the studied hybrids in comparison to prediction in E. grandis There was, however, a decrease in the correlations between predicted and realised clonal performances with increasing genetic distance between the parents. Furthermore, the genetic values were better predictors of clonal performance than breeding values and genetic values which were based on higher assumptions of non-additive genetic variances (37% of total genetic variance) were more efficient than those based on assumptions of lower proportions (20%). This study indicates that BLUP methods may be efficient in predicting the clonal performance in the three hybrid populations that were investigated. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Genetics / unrestricted

The future of aviation technology is transitioning to cleaner, more efficient and higher endurance aircraft solutions. As fully electric propulsion systems still fall short of the operational requirements of modern day aircraft, there is increasing pressure and demand for the aviation industry to explore alternatives to fossil fuel driven propulsion systems. The primary focus of this research is to experimentally evaluate hybrid electric propulsion systems (HEPS) for Unmanned Aerial Vehicles (UAV) which combine multiple power sources to improve performance. HEPS offer several potential benefits over more conventional propulsion systems such as a smaller environmental impact, lower fuel consumption, higher endurance and novel configurations through distributed propulsion. Advanced operating modes are also possible with HEPS, increasing the vehicle’s versatility and redundancy in case of power source failure. The primary objective of the research is to combine all of the components of a small-scale HEPS together in a modular test bench for evaluation. The test bench uses components sized for a small-scale UAV including a 2.34kW two-stroke 35cc engine and a 1.65kW brushless DC motor together with an ESC capable of regenerative braking. Individual components were first tested to characterize performance, and then all components were assembled together in a parallel configuration to observe system-level performance. The parallel HEPS is capable of functioning in the four required operating modes: EM Only, ICE Only, Dash Mode (combined EM and ICE power) as well as Regenerative Mode where the onboard batteries get recharged. Further, the test bench was implemented with a supervisory controller to optimize system performance and run each component in the most efficient region to achieve torque requirements programmed into mission profiles. The logic based controller operates with the ideal operating line (IOL) concept and is implemented with a custom LabView GUI. The system is able to run on electric power or ICE power interchangeably without making any modifications to the transmission as the one-way bearing assembly engages for whichever power source is rotating at the highest speed. The most impressive of these sets of tests is the Dash mode testing where the output torque of the propeller is supplied from both the EM and ICE. Working in tandem, it was proved that the EM was drawing 19.9A of current which corresponds to an estimated 0.57Nm additional torque to the propeller for a degree of hybridization of 49.91%. Finally, the regenerative braking mode was proven to be operational, capable of recharging the battery systems at 13A. All of these operating modes attest to the flexibility and convenience of having a hybrid-electric propulsion system. The results collected from the test bench were validated against the models created in the aircraft simulation framework. This framework was created in MATLAB to simulate the performance of a small UAV and compare the performance by swapping in various propulsion systems. The purpose of the framework is to make direct comparisons of HEPS performance for parallel and series architectures against conventional electric and gasoline configuration UAVs, and explore the trade-offs. Each aircraft variable in the framework was modelled parametrically so that parameter sweeps could be run to observe the impact on the aircraft’s performance. Finally, rather than comparing propulsion systems in steady-state, complex mission profiles were created that simulate real life applications for UAVs. With these experiments, it was possible to observe which propulsion configurations were best suited for each mission type, and provide engineers with information about the trade-offs or advantages of integrating hybrid-electric propulsion into UAV design. In the Pipeline Inspection mission, the exact payload capacities of each aircraft configuration could be observed in the fuel burn versus CL,cruise parameter sweep exercise. It was observed that the parallel HEPS configuration has an average of 3.52kg lower payload capacity for the 35kg aircraft (17.6%), but has a fuel consumption reduction of up to 26.1% compared to the gasoline aircraft configuration. In the LIDAR Data collection mission, the electric configuration could be suitable for collection ranges below 100km but suffers low LIDAR collection times. However, at 100km LIDAR collection range, the series HEPS has an endurance of 16hr and the parallel configuration has an endurance of 19hr. In the Interceptor mission, at 32kg TOW, the parallel HEPS configuration has an endurance/TOW of 1.3[hr/kg] compared to 1.15[hr/kg] for the gasoline aircraft. This result yields a 13% increase in endurance from 36.8hr for gasoline to 41.6hr for the parallel HEPS. Finally, in the Communications Relay mission, the gasoline configuration is recommended for all TOW above 28kg as it has the highest loiter endurance. / Graduate

Mobile generation platforms are very common among both military and civilian applications. However, in military applications getting fuel to the front lines can come at a very high cost. This cost is both financial, costing upwards of hundreds of dollars a gallon, and human, with resupply convoys being the leading cause of casualties in today's warfront. Diesel generators operate much more efficiently at higher loads, rather than the lower loads that the systems normally operate at. To improve fuel efficiency, a hybridized generator system is proposed. This system combines a standard generator with a large rechargeable battery pack. The addition of the battery pack allows for several unique power scenarios to occur through power generation. The battery pack functions to provide an efficient storage capability for the system. During times of excess load, the battery and generator work together. This allows for algorithms to manage the generator set to operate at peak efficiency while addressing load spikes. A system like this has been theoretically designed and a simulation has been developed to determine the impact over a standard system. Actual load cycle information from military sources has been used to evaluate the concept. The results of the simulation show increase efficiency, in the low load scenarios, to more than double the standard generator efficiency. / Master of Science

Les matériaux hybrides nanotubes de carbone remplis par des matériaux ferromagnétiques (NTCFM) présentent un fort potentiel pour des applications en électronique de spin. Leurs propriétés magnétiques dépendent fortement de la qualité de leur synthèse : densité, orientation et efficacité de remplissage. Deux méthodes d’élaboration des (NTC-FM) ont été utilisées : i) synthèse ex-situ après ouverture mécanique des nanotubes élaborés par arc électrique et in-situ pendant la synthèse par arc électrique, ii) synthèse par dépôt vapeur chimique assisté par plasma (PECVD) en présence de catalyseurs Co et Co/Pd. Les deux approches de confinement des nanotubes de carbone avec des métaux ferromagnétiques ont été comparées. La première méthode de synthèse des nanotubes hybrides a montré que l’approche par arc électrique in-situ est plus efficace surtout par l’ajout d’un promoteur comme l’yttrium (Y) et le soufre (S). Les différentes proportions catalytiques au cours de la synthèse ont été variées et leur influence sur la production des nanotubes hybrides étudiée. La qualité et la quantité des nanotubes obtenus ainsi que les rendements disponibles au cours de la synthèse ont été améliorés. La réponse magnétique est également meilleure. La synthèse des nanotubes hybrides par PECVD a révélé que l’adjonction d’une couche de palladium comme catalyseur avec le cobalt conduit à une nette amélioration de la densité, du remplissage et de l’alignement des nanotubes. Les mesures magnétiques ont mis en évidence la contribution d’une anisotropie de forme que l’on peut associer à une meilleure orientation géométrique des nanotubes par rapport au substrat. / Hybrid materials as carbon nanotubes filled with ferromagnetic materials (FMCNT) have great potential for spintronic applications. Their magnetic properties strongly depend on their density,orientation and filling efficiency. Two preparation methods of (FMNTC) were used: i) ex-situ synthesis where mechanical opening of the nanotubes produced by electrical arc is first achieved and in-situ during the synthesis by electrical arc discharge, ii) synthesis by chemical vapor deposition enhanced by plasma (PECVD) in the presence of cobalt Co and Co / Pd catalysts. Our results showed that the arc in-situ approach is more effective especially with the addition of a filling promoter such as yttrium (Y) and sulfur (S). Different proportions of catalyst were varied and their influence on the yield of hybrid nanotubes studied. The quality and quantity of obtained nanotubes as well as their yields and magnetic properties were improved. The PECVD synthesis revealed that the addition of a thin layer of palladium (~6 nm) as a co catalyst with the cobalt leads to a significant improvement inthe density of the filler and the alignment of the nanotubes. Magnetic measurements thereby demonstrated the contribution of a shape anisotropy that can be associated with a better geometric orientation of the nanotubes to the substrate.

After the military intervention in Ukraine in 2014, and the swift, bloodless annexation of Crimea, the international community recognized Russia as an expert on hybrid warfare. However, the ongoing conflict in Donbas unleashed by Moscow during the second less successful hybrid campaign remains a sore point not only for Ukraine but also for Russia which has to cope with costly consequences in order not to lose in the East of Ukraine and more importantly in its undeclared war on the West. This thesis conducts a comparative analysis of two Russian hybrid warfare models: (1) in Crimea; (2) in Eastern Ukraine, and focuses on the following research questions: Why was the Russian hybrid warfare in Crimea more successful than in Donbas? What measures can the state take to improve its ability to face hybrid attacks? The findings reveal that despite the presence of a set of common factors, the different degrees of success and outcomes of both cases are attributable to the fact that successfully employing the full spectrum of hybrid warfare, is actually bound not only to a number of prerequisites but also with specific favorable features of the conflict zone and several critical elements. While hybrid tactics vary depending on country and region, it is built on exploiting the enemy's vulnerabilities, the...

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This research investigates the effects of an electric turbocharger in a hybrid electric powertrain. First generic vehicle models are created and run to understand the overall powertrain requirements of torque, power and energy of a performance consumer vehicle. Then a low fidelity baseline model of a conventional vehicle is created in Simulink to serve as a baseline measure. To analyze an electric turbocharger system a high-fidelity model in AMESIM of a 4 cylinder turbocharged engine was modified. This engine model was analyzed using virtual dynamometer tests and a simplified look-up table based controller was developed for the electric motor within the electric turbocharger. Next this engine model was inserted within three different types of hybrid powertrain architectures models in AMESIM. Each hybrid powertrain required a unique supervisory controller which was developed using Stateflow in Simulink. These controller algorithms were imported into AMESIM and the model was simulated over standard drive cycles. Since a very wide variation of electrification level exists within hybrid powertrains the supervisory controllers are calibrated for charge-sustaining simulations. This allows for impartial comparisons across the hybrid architectures. Lastly a track drive cycle was developed to understand electric turbocharger effects under high performance loading conditions / Thesis / Master of Applied Science (MASc) / Turbochargers on internal combustion engines can utilize a portion of waste exhaust energy to pump more air into the cylinder leading to greater power and efficiency. A modern high performance 4-cylinder turbocharged engine is capable of replacing a V6 engine of much higher cylinder displacement. However turbocharged engines suffer from ‘turbo lag’ when the engine cannot immediately produce power. An electric turbocharger can virtually eliminate this ‘turbo lag’ as well as generate electricity from excess energy the turbocharger does not use. Electric turbochargers have been development by researchers and various automotive manufacturers. However the potential effects of such a system within the framework of a hybrid electric powertrain in a consumer vehicle has not been quantified. The objective of this research is to use high fidelity models to investigate the effects of an electric turbocharger system within a hybrid powertrain.