Although it is now generally accepted that, in the west, irrigation and drainage are necessarily complementar,y practices, the realization has been slow in developing. Recent estimates indicate that about 8 million acres of land under irrigation in the 17 western states require drainage. For most irrigated lands a depth to groundwater of at least five to ten feet is desirable. Very high capital as well as annual maintenance costs would be involved in meeting this minimum requirement with the usual types of tile and open drains. Indeed, in most instances it cannot economically be accomplished. The purpose of this study is to determine the degree to which pumping groundwater, so successful in certain other areas, can contribute to the solution of the drainage problem in the Delta Area, Utah. The data presented herein have been collected in meeting one of the objectives of a cooperative research agreement between the four Millard County drainage districts, the U. S. Regional Salini ty Laboratory, and Utah Agricultural Experiment Station, namely, "to study the feasibility and costs of drainage by pumping from wells in the area".

In March 2010, parents and community activists in rural Sunflower County, Mississippi, organized and enacted a boycott of the local public schools, which led to a comprehensive accreditation audit by the Mississippi Department of Education and the subsequent takeover of the local education agency. This study examines the boycott's connections to local discourses of protest in the Black community, to local histories and contemporary quality of life, and to the circulations of power evident in the grassroots activism and in the state intervention. This work is situated in an interdisciplinary theoretical framework which draws on place studies, rhizome theory, Levinasian ethics, and Critical Discourse Analysis. Using ethnographic methods of data collection and Critical Discourse Analysis of data, I position the boycott in context and examine its rhizomatic roots and offshoots in discourse.

Algae-derived biodiesel is currently under investigation as a suitable alternative to traditional fossil-fuels. Though it possesses many favorable characteristics, algae remains prohibitively expensive to mass produce and distribute. The most economical means of growing algae are large-scale open pond raceways. These, however, suffer from low culture densities; this fact impacts the cost directly through diminished productivity, as well as indirectly by raising costs due to the necessity of dewatering low culture density raceway effluent. Algae, as a photosynthetic organism, achieves higher culture densities when sufficient light is provided. In open ponds this can be accomplished by frequently cycling algae to the raceway surface. The current work examined delta wing vortex generators as a means of instigating this cycling motion. In particular the impact of spacing and angle of attack was analyzed. These vortex generators were found to significantly increase vertical mixing when placed in a series, developing precisely the motion desired. Their impact on power requirements was also examined. Specifically it was shown that increases in spacing and decreases in angle of attack result in lower power consumption. It was demonstrated that the most efficient mixing generation is achieved by larger spacings and smaller angles of attack. The impact that these devices had on raceway turbulence as measured by dissipation rate was also investigated and compared to published values for algae growth. Raceways were found to be significantly more turbulent than standard algae environments, and adding delta wings increased these levels further.

A promising feedstock for biofuels is microalgae. The most economical means of cultivating microalgae is via open raceway ponds. However, a large gap in economic feasibility exists between algae-based biofuels and traditional petroleum fuels. Recent research at Utah State University has focused on increasing biomass growth by implementing Delta Wings (DWs). DWs are placed facing the incoming flow, with a 40 degree angle of attack to create large vortices which travel downstream. The trailing vortices increase vertical mixing, which in turn increases algal growth. Past researchers at USU quantified vertical mixing with new metrics, optimized various raceway operating conditions, and established a positive correlation between the newly defined metrics and algal growth. Research was performed with the aid of a small-scale clear acrylic raceway. Both stereo particle image velocimetry (SPIV) and acoustic Doppler velocimetry (ADV) were used to estimate the recently defined mixing metric: the vertical mixing index (VMI). The focus of this work is to ascertain additional preferred operating conditions, in particular those unique to large scale raceways, with the aid of a computational fluid dynamics (CFD) model validated by experimental data. Three case studies are presented herein, which analyze the DW vertical position (VP), array spacing ratio (ASR), and the projected height to depth ratio (PHDR). The criteria for these studies are the VMI and power consumption. While it was previously assumed that vertically centering the DW centroid was optimal, the first case study revealed the ideal VP to be far lower. The lowest possible VP allows the trailing vortices to travel further downstream, resulting in increased vertical mixing. The second case study entails modeling complete arrays of DWs with various spacing. This model was the first to account for an increase in the number of allowable DWs with a decrease in array spacing. The ASR study revealed the ideal array spacing to be approximately half a DW, as opposed to the initial estimate of a full DW. The third case study confirmed the largest allowable DW to be superior.

Bunces Pass is an unstructured tide-dominated inlet just north of the main entrance to Tampa Bay, Florida. The inlet has been stable for at least 130 years, as the size, shape, and orientation have remained unchanged. The morphological evolution of the Bunces Pass ebb-tidal delta is influenced by adjacent inlets. Historically, the ebb tidal delta was extremely large, due to the presence of the south channel of Pass-A-Grille Pass. As the tidal prism decreased through the south channel, the sheltering effect produced by the large ebb tidal delta diminished, and large volumes of sand began migrating shoreward. Sediment from the ebb tidal delta accreted along "the Reefs", formed both North Bunces Key and South Bunces Key, and accreted on Mullet Key south of the inlet. Tidal currents at Bunces Pass are primarily ebb-dominant during both summer and winter seasons, though there is flood dominance for several days during neap tides. The ebb dominance is primarily due to the large back-barrier embayment of Tampa Bay, which results in a spring ebb tidal prism of 2.02 x 107 m³. This tidal prism is more than 400 times the corresponding littoral drift. It is primarily responsible for maintaining the inlet's stability, as well as the development of its large ebb-tidal delta. Sediments from the ebb tidal delta at Bunces Pass reflect different degrees of wave versus tidal energy. The strongest tidal currents present throughout the entire ebb tidal delta complex mechanically weather shell gravel in the main channel, producing a shelly, fine quartz sand with relatively high amounts of shell gravel and carbonate sand. This sub-facies is also present on the north channel margin linear bar, due to the interaction of waves, tidal currents, and a southerly littoral drift along this coastal reach. Fine, quartz sand dominates the off shore and swash platform environments. The present situation at Bunces Pass shows a stabilized, tide-dominated inlet with a large, elongate ebb delta that is unlikely to change significantly in the future if present conditions are maintained. The prevalent ebb-dominance suggests that the inlet is hydraulically connected to the adjacent and much larger Egmont Channel inlet system, which also serves Tampa Bay. Strong ebb-tidal currents have kept Bunces Pass in dynamic equilibrium with its surrounding environment. The large ebb tidal prism is responsible for explaining how a tide-dominated inlet is maintained in a microtidal environment.

[Truncated abstract] Environmental changes have had major impacts on past human societies across the globe, and a better understanding of this human-environment interaction is necessary for building societies with resilience towards future environmental change, and to effectively conserve areas of natural environments into the future. Regions such as the Yangtze delta, that have a long history of rice cultivation (dating to at least ca. 7000 BP) and a high density of prehistoric sites, provide an ideal backdrop to study both long-term human-environment interactions, and the environmental impacts of agricultural societies. This study aims to provide Holocene palaeoenvironmental reconstructions for three study sites in the Yangtze delta region, with the principle objectives of detecting human activity – particularly that associated with the development of rice agriculture – and identifying environmental changes within the palaeoenvironmental records. A parallel aim is to develop the use of quantitative biomarker and compound specific isotope analyses in Holocene palaeoenvironmental investigations, including in the detection of early agricultural environments, through analysis of sedimentary deposits. Palaeoenvironmental records for the three study sites, Qingpu, Guangfulin and Liangzhu, cover the time period from ca. 12,000 to ca. 400 BP. '...' Greater proportions of coniferous and deciduous taxa early in the records (prior to ca. 7000 BP) indicate comparatively cooler conditions, while the increased abundance of Chenopodiaceae during that time suggests both cooler conditions and a greater marine influence in the region. Palaeoenvironmental data obtained during this study suggest agriculture in the delta region to have gradually increased in importance from ca. 7000 – 2400 BP. The Guangfulin study site yielded the earliest evidence of agricultural activity, dating to ca. 7000 BP, principally in the form of a corresponding increase in Poaceae (Oryza comp.) abundance and decline of arboreal forest taxa. Subsequent periods of agricultural intensification are noted at ca. 5360 BP at Liangzhu and ca. 4700 BP at Guangfulin. Following the final period of intensification at Qingpu and Guangfulin (ca. 2400 BP), the extent of cultivated land in the delta region may have been comparable to modern times. Technological development during the early dynasties, particularly the greater availability of iron tools, is likely to have been a major factor driving the agricultural intensification detected ca. 2400 BP. The large tracts of natural vegetation detected by this research prior to ca. 2400 BP, would have afforded a degree of resilience to the human inhabitants of the delta region. Following the contraction of natural vegetation in the delta region, societies would have gained some resilience through access to the extensive trade network of the Chinese state. Resilience acquired through these means may, in part, account for the longevity of agricultural societies in the Yangtze delta region of China.

This research discusses the use of Delta in regulating the investment behaviour of the Trustees of Self-Managed Superannuation Funds (SMSFs) who use Exchange Traded Options (ETOs) in their investment strategies. An ETO represents a contract between two parties, giving the taker (the buyer) the right, but not the obligation, to buy or sell a parcel of shares at a predetermined price, on or before a predetermined date, to or from the writer (the seller). It is acceptable for SMSF Trustees to use ETO investments as part of their overall investment strategy, providing that leverage or mere speculation are not the reasons behind that investment. It is important to note that neither the Regulator, the Australian Taxation Office (ATO), nor its predecessor, the Australian Prudential Regulatory Authority (APRA), actually state what constitutes 'speculation', or what the allowable uses for derivatives are. There are no practical guidelines. This is a key issue for this research, which aims, as practically as possible, to fill these crucial gaps. A Trustee must abide by their superannuation fund's overriding covenants and investment strategy, and inform its members, through Risk Management Statements, of the trust's derivative strategy. While ETOs can be used to manage risk, they also carry a level of risk themselves. Delta measures an ETO's value movement in correlation with a movement in the option's underlying share price. An ETO carrying a low Delta generally means a cheaper price (premium) per contract than an option carrying a higher Delta. The lower the Delta, however, the lower the chance there is of a positive result for the buyer. This research shows that an ETO Delta of less than 0.2 gives results in favour of buyers in only 11 out of 100 occurrences. This figure rises to 42 out of 100 when Delta is greater than 0.8. From the sampled data, there is an overall financial loss to the buyer of -1.91%, with the financial return results being mixed at all levels of Delta. The overall return results have been compiled without preference to market direction, and clearly highlight the natural premium bias (which the buyer pays) to the seller. What this data does is reenforce the need for Trustees to have a solid view of market directions, or a set strategy in place, as buyers of ETOs. The conclusions drawn from the findings show that the chance of loss (when buying), or gain (when selling) ETOs with a Delta of; - less than 0.20 is 89%; - less than 0.40 is 74%; - less than 0.60 is 66%; - less than 0.80 is 57%; - greater than 0.80 is 58%; For example, a Trustee buying an ETO with a Delta of less than 0.20, faces an 89% chance of loss; a Trustee selling an ETO with a Delta of less than 0.20, faces an 89% chance of gain. The findings on overall financial returns (profit or loss) offer additional support to this critical review of Delta as a risk measurement tool. Whist it is impossible to know the motives or actual positions of portfolio managers of SMSF at any time, the aim of the thesis is to provide a measurement tool that can be used to assist the trustee at any given time by measuring the option risk element alone. When interpreting the findings, the reader must remember that ETO strategies are numerous, and a high-risk profile for one strategy may represent a low risk for another. Further to this, an ETO strategy's risk profile may change with the overlaying of another ETO. For example, where a Call option is bought, the risk involved in that purchase is represented by the premium paid. However, another Call option can then be sold against that position, with a later (or earlier) date to expiry, and with a higher strike price. This 'overlay' reduces the initial risk, but impacts on the maximum gain. It is vital that Trustees have a solid understanding of the basics of ETO strategies before considering using Delta as a measure of risk. The research proposes some guidelines Trustees can use when assessing an ETO strategy against their derivative/investment risk profile. For example, a Trustee buying an ETO with a Delta of less than 0.20, faces an 89% chance of loss; a Trustee selling an ETO with a Delta of less than 0.20, faces an 89% chance of gain. The findings on overall financial returns (profit or loss) offer additional support to this critical review of Delta as a risk measurement tool. Whist it is impossible to know the motives or actual positions of portfolio managers of SMSF at any time, the aim of the thesis is to provide a measurement tool that can be used to assist the trustee at any given time by measuring the option risk element alone. When interpreting the findings, the reader must remember that ETO strategies are numerous, and a high-risk profile for one strategy may represent a low risk for another. Further to this, an ETO strategy's risk profile may change with the overlaying of another ETO. For example, where a Call option is bought, the risk involved in that purchase is represented by the premium paid. However, another Call option can then be sold against that position, with a later (or earlier) date to expiry, and with a higher strike price. This 'overlay' reduces the initial risk, but impacts on the maximum gain. It is vital that Trustees have a solid understanding of the basics of ETO strategies before considering using Delta as a measure of risk. The research proposes some guidelines Trustees can use when assessing an ETO strategy against their derivative/investment risk profile. (table inserted) The findings from 2400 data samples show strong trends in support of the underlying premise (see Figure: Positive Results Versus Delta (ETO Buyers) below). Given these findings, the research concludes that Delta can be used as a measure of risk by SMSF Trustees. Delta may not be suitable, however, for measuring multiple layers of combined ETO positions, a type of derivative strategy not suited to or usual in the context of measuring risk within a SMSF. (table inserted) There is a major difference between simple and simplistic solutions offering practical answers in an environment of increasing complexity. Often, simple solutions offer far more value to the less experienced, when compared to complex ones, especially given the growing number of SMSFs, and the increasing lack of expertise in the areas of superannuation and risk management that this growth implies.

Le convertisseur analogique-numérique fondé sur le principe de modulation SD est capable de fournir une très haute résolution. Bien qu'il nécessite un suréchantillonnage, il est peu sensible aux imperfections des composants. Le modulateur SD classique est donc très populaire pour les applications de bande étroite demandant une très haute résolution. Dans cette thèse, nous nous sommes intéressés à l'extension des applications du modulateur SD vers une bande passante plus large. Nous avons tout d'abord étudié l'architecture parallèle basant sur la modulation SD et proposé une nouvelle architecture basant sur la modulation SD passe-haut et l'entrelacement temporel permettant de réduire de façon significative le problème caractéristique du parallélisme, à savoir la disparité entre les canaux. Nous avons ensuite étudié le modulateur SD passe-haut et proposé une implémentation en technique des capacités commutées. Ce nouveau modulateur, contrairement au modulateur classique, est complètement immune au bruit de basse fréquence et peut être utilisé non seulement dans une architecture parallèle, mais aussi de façon autonome. Nous avons aussi modélisé la plupart de non-idéalités du modulateur en VHDL-AMS pour finalement arriver à une méthodologie de conception descendante qui permet de dériver les spécifications de tous les blocs du circuit à partir de performance visée pour le système complet. L'implémentation d'un modulateur SD passe-haut d'ordre 2 et un convertisseur SD passe-haut en combinant avec l'entrelacement temporel a été réalisée en technologie CMOS 0,35 mm. Enfin, notre travail nous a permis de démontrer non seulement l'avantage du modulateur SD passe-haut, mais aussi un perspective prometteur du modulateur SD parallèle pour les applications de très large bande.

<p>The thesis demonstrates a low-cost, low-bandwidth and low-resolution Analog-to- Digital Converter(ADC) in 0.35 um CMOS Process. A second-order Sigma-Delta modulator is used as the basis of the A/D Converter. A Semi-Uniform quantizer is used with the modulator to take advantage of input distributions that are dominated by smaller-amplitude signals e.g. Audio, Voice and Image-sensor signals. A Single-bit feedback topology is used with a multi-bit quantizer in the modulator. This topology avoids the use of a multi-bit DAC in the feedback loop – hence the system does not need to use digital correction techniques to compensate for a multi-bit DAC nonlinearity. </p><p>High-Level Simulations of the second-order Sigma-Delta modulator single-bit feedback topology along with a Semi-Uniform quantizer are performed in Cadence. Results indicate that a 5-bit Semi-Uniform quantizer with a Over-Sampling Ratio of 32, can achieve a resolution of 10 bits, in addition, a semi-uniform quantizer exhibits a 5-6 dB gain in SNR over its uniform counterpart for input amplitudes smaller than –10 dB. Finally, this system is designed in 0.35um CMOS process.</p>

<p>Comparator is the main building block in an ADC architecture. Main purpose of the comparator is to compare a signal with a reference signal and produce an output depending on whether the input signal is greater or smaller than reference. Many architectures for comparators exist for various purposes. In this thesis, Latched comparator architecture is used for sigma delta modulator. This particular design has two main characteristics that are very important for sigma delta application. First characteristic is the cancellation of memory effect which increases the speed and reliability of the system and the second is, with this architecture, high sensitivity can be achieved.</p><p>The design and implementation of lathed comparator for sigma delta modulator is presented in this thesis work. Various non-linearities and performance parameters are discussed in detail. Practical implementation and circuit design issues are highlighted to achieve maximum sensitivity along with reasonable speed and accuracy.</p>