Successive Approximation (SAR) analog-to-digital converters are used extensively in biomedical applications such as CAT scan due to the high resolution they offer. Capacitor mismatch in the SAR converter is a limiting factor for its accuracy and resolution. Without some form of calibration, a SAR converter can only achieve 10 bit accuracy. In industry, the CAL-DAC approach is a popular approach for calibrating the SAR ADC, but this approach requires significant test time. This thesis applies the“Split-ADC" architecture with a deterministic, digital, and background self-calibration algorithm to the SAR converter to minimize test time. In this approach, a single ADC is split into two independent halves. The two split ADCs convert the same input sample and produce two output codes. The ADC output is the average of these two output codes. The difference between these two codes is used as a calibration signal to estimate the errors of the calibration parameters in a modified Jacobi method. The estimates are used to update calibration parameters are updated in a negative feedback LMS procedure. The ADC is fully calibrated when the difference signal goes to zero on average. This thesis focuses on the specific implementation of the“Split-ADC" self-calibrating algorithm on a 16 bit, 1 MS/s differential SAR ADC. The ADC can be calibrated with 105 conversions. This represents an improvement of 3 orders of magnitude over existing statistically-based calibration algorithms. Simulation results show that the linearity of the calibrated ADC improves to within ±1 LSB.

Made available in DSpace on 2014-06-11T19:22:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-22Bitstream added on 2014-06-13T20:28:26Z : No. of bitstreams: 1 costa_chmc_me_botfca.pdf: 444896 bytes, checksum: 79a884c18686d0a77b3357b8cbc1bcfb (MD5) Bitstreams deleted on 2015-08-07T12:19:54Z: costa_chmc_me_botfca.pdf,. Added 1 bitstream(s) on 2015-08-07T12:20:56Z : No. of bitstreams: 1 000678831.pdf: 1444305 bytes, checksum: d3e614871d6cd55de66eda01f9f2bdd0 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / No sistema plantio direto praticamente não há revolvimento do solo e o consequente acúmulo de fertilizantes na superfície acelera o processo de acidificação, contínuo e acentuado que ocorre naturalmente em solos de regiões úmidas, onde, geralmente, é observada baixa disponibilidade de nutrientes e elevados teores de alumínio. Assim, da mesma forma que no sistema de cultivo convencional, no sistema plantio direto também existe a necessidade de aplicação de insumos em superfície, especialmente, materiais corretivos de acidez. Dentro deste enfoque, o trabalho foi desenvolvido na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas – UNESP, Campus de Botucatu (SP), dando continuidade a um projeto de pesquisa que vem sendo conduzido desde 2002, com o objetivo de avaliar o efeito residual da aplicação superficial de corretivos na correção da acidez do solo, bem como na nutrição, na produtividade das culturas da soja e do sorgo e na produção de matéria seca e acúmulo de nutrientes da aveia-preta em região de inverno seco. O delineamento experimental utilizado foi em blocos casualizados em parcelas subdivididas, com 4 repetições. As parcelas foram constituídas por quatro doses de calcário (0, 1000, 2000 e 4000 kg ha-1) e as subparcelas por duas doses de gesso agrícola (0 e 2100 kg ha-1), aplicado em novembro 2004. Como cultura de verão foi utilizada a cultura da soja e na entressafra as culturas da aveia-preta e sorgo granífero. A aplicação de calcário em superfície promoveu diminuição da acidez e elevação nos teores de fósforo, cálcio, magnésio e matéria orgânica, em praticamente todo perfil do solo. A aplicação de gesso agrícola promoveu aumentos nos 2 teores de Ca trocável e S-SO42-, e diminuição no teor de Al trocável no solo... / In no tillage system the absence of soil mobilization consequently decreases places fertilizers on surface, affecting the acidification process. Like in conventional system, in no tillage it is also necessary input application, especially materials for acidity correction. The experiment was carried out in an experimental area, in the city of Botucatu (SP, Brazil), continuing a research project that has been conducted since 2002, to evaluate the long-term effects of surface application of lime and gypsum on acidity correction, nutrition, yield of soybean and sorghum, and dry matter production and nutrients accumulation on black oat in a dry winter region. The experimental design was the completely randomized with subdivided plots and four replications. The mains plots consisted of four dolomite limestone levels (0, 1000, 2000 e 4000 kg ha-1) and the subplots consisted areas with and without gypsum (0 and 2100 kg ha-1), applied in November 2004. Soybean was the summer crops and the off-season crops are black oat and grain sorghum Lime surface application reduced soil acidity and increased phosphorus, calcium, magnesium and organic matter, practically all the soil profile. Phosphogypsum application promoted increasing exchangeable Ca and S-SO42- contents, and decreased exchangeable Al in the soil, favoring the effects of surface liming on soil properties, mainly the surface layer (0-0.20 m). Base saturation values obtained at a depth of 0-0.20 m with liming were lower than those estimated by BS method, even with phosphogypsum application. Liming increased, on soybeans, foliar contents of N, P, Ca, Mg and S in 2008/09, and N, Ca and Mg, in 2009/10. In the presence of phosphogypsum increased the levels of N In no tillage system the absence of soil mobilization consequently... (Complete abstract click electronic access below)

Quantum computing has enormous potential, but this can only be realised if quantum errors can be controlled sufficiently to allow quantum algorithms to be completed reliably. However, quantum-error-corrected logical quantum bits (qubits) which can be said to have achieved meaningful error suppression have not yet been demonstrated. This thesis reports research on several topics related to the challenge of designing fault-tolerant quantum computers. The first topic is a proposal for achieving large-scale error correction with the surface code in a silicon donor based quantum computing architecture. This proposal relaxes some of the stringent requirements in donor placement precision set by previous ideas from the single atom level to the order of 10 nm in some regimes. This is shown by means of numerical simulation of the surface code threshold. The second topic then follows, it is the development of a method for benchmarking and assessing the performance of small error correcting codes in few-qubit systems, introducing a metric called 'integrity' - closely linked to the trace distance -- and a proposal for experiments to demonstrate various stepping stones on the way to 'strictly superior' quantum error correction. Most quantum error correcting codes, including the surface code, do not allow for fault-tolerant universal computation without the addition of extra gadgets. One method of achieving universality is through a process of distilling and then consuming high quality 'magic states'. This process adds additional overhead to quantum computation over and above that incurred by the use of the base level quantum error correction. The latter parts of this thesis report an investigation into how many physical qubits are needed in a `magic state factory' within a surface code quantum computer and introduce a number of techniques to reduce the overhead of leading magic state techniques. It is found that universal quantum computing is achievable with ∼ 16 million qubits if error rates across a device are kept below 10^-4. In addition, the thesis introduces improved methods of achieving magic state distillation for unconventional magic states that allow for logical small angle rotations, and show that this can be more efficient than synthesising these operations from the gates provided by traditional magic states.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Debts are common in every companies live. This dissertation is about debt and its adjustments. These adjustmensts are represented by practical examples with accounting solution.

The work presented involved simulation and experimental studies aimed at improving the methodology of positron annihilation lifetime spectroscopy (PALS), and applied PALS to gain a better understanding of doping mechanisms in ABO3 perovskite oxide materials. Reliable decomposition of PALS spectra requires an accurate description of the instrument resolution function (IRF) and the extrinsic, source component, annihilation events. The source terms include annihilations with the crystallites of the radionuclide and in the thin foil normally used to support the source. In principle both the IRF and the source correction terms can accurately be determined if samples exhibiting a true single lifetime component are measured. A series of annealing studies was performed on commercially available high purity polycrystalline metal samples to reduce the defect concentration below the approximate 0.1 ppm detection limit of PALS. The study showed that despite the numerous reports in literature it was not possible to reproduce the results with similar annealing conditions or sample purity. The possibility of utilising two-lifetime materials to enable the extraction of source correction terms is analysed using simulations, and by experiments on commercially available pure polycrystalline metals. The positron source is commonly deposited on, and supported by, a thin Kapton foil. As part of this work variable energy PALS (VE-PALS) performed at the Munich Research Reactor FRMII on Kapton foils were analysed. This enabled one of the source correction terms to be unambiguously determined. In consequence, the source correction terms for a Kapton supported positron source were extracted from measurements using annealed nickel exhibiting two positron lifetime components. PALS was applied to a study on donor doping of PbTiO3 ceramics using a series of lanthanide-ions. It has been proposed that the smaller Ln-ions may act as amphoteric dopants substituting either on the A-site as a donor, or on the Bsite as an acceptor. In this study Ln-ions in size from La down to Er were studied. A systematic variation in the average positron lifetime was observed where the value was constant from La to Gd and then reduced for the smaller ions. The decrease in average lifetime provides evidence for a reduction in the fraction of trapping to A-site related vacancy defects. The onset of a reduction in the average lifetime between Gd and Dy provides evidence for a change in the doping mechanism resulting in a relative reduction in the fraction of A-site vacancy positron trapping. In contrast to PbTiO3, donor doping of SrTiO3 normally results in electron charge compensation. Recently this has been very clearly demonstrated for La3+ doped SrTiO3 thin films grown by molecular beam epitaxy (MBE) which exhibit exceptional electron mobilities. A series of MBE films grown at University of California Santa Barbara were measured by VE-PALS at FRMII and have been analysed here. Strontium vacancies were identified, and a reduced bulk lifetime component was also observed. This enabled bulk lifetime values to be obtained from two of the films which were in good agreement with the previously obtained values from single crystal samples. A PALS study was also performed on a series of B-site donor, Nb, doped SrTiO3 crystals. High intensity reduced bulk components were observed and enabled measurements of the bulk lifetime. The highest Nb doping level samples showed the most intense reduced bulk lifetime but also clearly demonstrated the presence of Sr vacancies. The observation of A-site vacancy defects for both Nb-doped and La-doped SrTiO3 suggest that formation of these defects is preferred and are independent of the site of incorporation of the donor ion. Studies were also performed on acceptor doped SrTiO3. PALS measurements were made on a series of Fe-doped SrTiO3 ceramic samples, and VE-PALS measurements on pulsed laser deposition of Fe-doped SrTiO3 thin film samples were analysed. The positron lifetime measurements on the ceramic samples showed a dominant 166(3) ps component, a value less than the Ti-vacancy lifetime. It is proposed that the component contains a contribution from positrons trapping at oxygen vacancy substitutional Fe impurity complexes with a local charge that is neutral or negative. The measurements on the series of Fe-doped PLD SrTiO3 films suggest a complex relation between the vacancy defect content of a film and both the Fe-doping and PLD growth conditions. Films grown with higher laser fluence values contained Sr vacancy defects, in contrast to previous studies of acceptor doped perovskites. Films grown with low laser fluence or with high Fe-content showed dominant trapping to Ti-vacancy related defects.

>Magister Scientiae - MSc / The lack of monitoring of non-perennial rivers is a major problem for water resources management, despite their significance in satisfying agricultural, economic and recreational needs. Pools in non-perennial rivers are not monitored, due to their remoteness. Remote sensing offers a promising alternative for the monitoring of changes in water storage in these pools. This study aims to assess the extent to which remotely-sensed datasets can be used to monitor the spatio-temporal changes of water storage of pools along non-perennial rivers in the Western Cape. The objectives of this study are: (1) to determine a suitable image preprocessing and classification technique for detecting and monitoring surface water along nonperennial rivers, and (2) to describe the spatial and temporal changes of water availability of pools along non-perennial rivers, using remotely sensed datasets. The Normalised Difference Water Index (NDWI), Modified NDWI (MNDWI), Normalised Difference Vegetation Index (NDVI), Automated Water Extraction Index for shadowed (AWEIsh) and non-shadowed regions (AWEInsh) and the Multi-Band Water Index (MBWI) classification techniques were investigated in this study, using the Sentinel-2 and Landsat 8 datasets. In-situ measurements were used to validate the satellite-derived datasets, while the use of high resolution aerial photography and Digital-Globe WorldView imagery were further compared to the results. The results suggested that the NDWI is the most suitable classification technique for identifying water in pools along non-perennial rivers throughout the Western Cape. The NDWI applied to the Sentinel-2 Top-of-Atmosphere (TOA) reflectance dataset had the highest overall accuracy of 85%, when compared to the Sentinel-2 Dark Object Subtraction 1 (DOS1) atmospheric correction, Sentinel-2 Sen2Cor atmospheric correction, Landsat 8 TOA reflectance and Landsat 8 DOS1 atmospheric correction datasets. The incorporation of atmospheric correction was shown to eliminate surface water pixels in many of the smaller pools.

This thesis is a study of the air-sea fluxes of momentum, sensible heat and latent heat. Fluxes are estimated using the covariance, COARE2.6b bulk flux algorithm, and inertial dissipation methods. The bulk algorithm is validated against the covariance fluxes for the first time in a light-wind, shallow tropical sea, with strong atmospheric instability and low sea state conditions. The removal of ship motion contamination is investigated. This is the first study to quantify the errors associated with corrections for ship motion contamination, and the effects of motion contamination on the covariance calculated heat fluxes. Flow distortion is investigated. Bulk transfer coefficients and roughness lengths are computed and related to the sea state. Ship motion contamination is successfully removed in 86% of the runs. Error analysis of the motion removal algorithm indicates maximum uncertainties of 15% in the wind fluctuations, and 0.002 N/m/m for the wind stress. Motion correction changes the stress by more than 15% in half of the runs analysed. The ship is found to accelerate the mean air flow and deflect it above the horizontal. A correction is developed for the air flow acceleration. The scalar fluxes show good agreement on average for all the methods. As wind speed approaches zero, covariance wind stress is significantly larger than the bulk and inertial dissipation derived wind stress. The non-zero covariance wind stress is reflected in the drag coefficient, CdN10, and momentum roughness length, z0, which are much larger than the parameterisations used in the bulk algorithm. The MCTEX CdN10, wind speed (u10N) relation is 1000 x Cd10N = 1.03 + 7.88/(u10N)^2 0.8 &lt u10N &lt 7.5 m/s z0 is primarily a function of wind speed rather than sea state, with largest roughness lengths occurring as wind speed approaches zero. This relation is used in the bulk algorithm, yielding good agreement between covariance and bulk derived wind stress. A new parameterisation for the effects of gustiness, based on wind variance is developed. This brings the bulk wind stress into agreement with the covariance derived wind stress.

This case study was explored to determine effective error-correction/feedback methods for two ESL Korean children's writing (recounting task) in terms of accuracy, fluency and attitudes. Three different error-correction methods - written comments focusing on meaning by researcher (Case1), direct and global error-correction focusing on form by researcher (Case2) and self-directed error-correction using check lists by subjects (Case 3) - were applied over a period of 7 months. Thirty pieces of recount writing per subject were collected (10 pieces per case) and analysed by structured criteria of fluency and accuracy. Through participant observation, the subjects' changing attitudes were recorded in notes and video tapes. The results of the analysis showed that for Subject B, who was 7 years old and a more advanced writer of English than Subject A, self-directed error-correction using check lists (Case 3) was the most effective method in relation to both fluency and accuracy as well as attitude. Yet, for Subject A who was 5 years old and an early beginner in her writing, Case 1 seemed to be more effective in terms of fluency and attitude and Case 3 was likely to be more effective in terms of accuracy. In discussion, the method of error correction / feedback, the issue of ownership in children's writing including errorcorrection and the necessity of process writing were highlighted in the light of the whole context of the case study.

<p>This is a thesis report done as part of the Master of Science in Electronics Design Engineering given at Linköping University, Campus Norrköping. The thesis work is done at Ericsson AB in the spring of 2005. The thesis describes a method of removing variations in the tuning sensitivity of voltage-controlled crystal oscillators due to different manufacturing processes. These variations results in unwanted variations in the modulation bandwidth of the phase-locked loop the oscillator is used in. Through examination of the theory of phase-locked loops it is found that the bandwidth of the loop is dependent on the tuning sensitivity of the oscillator.</p><p>A method of correcting the oscillator-sensitivity by amplifying or attenuating the control-voltage of the oscillator is developed. The size of the correction depends on the difference in oscillator-sensitivity compared to that of an ideal oscillator. This error is measured and the correct correction constant calculated.</p><p>To facilitate the measurements and correction extra circuits are developed and inserted in the loop. The circuits are both analog and digital. The analog circuits are mounted on an extra circuit board and the digital circuits are implemented in VHDL in an external FPGA.</p><p>Tests and theoretical calculations show that the method is valid and able to correct both positive and negative variations in oscillator-sensitivity of up to a factor ±2.5 times. The bandwidth of the loop can be adjusted between 2 to 15 Hz (up to ±8 dB, relative an unmodified loop).</p>