Orientador: Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T10:31:27Z (GMT). No. of bitstreams: 1 Pimenta_LucianaBispo_M.pdf: 3231978 bytes, checksum: c2de8436ce07b62fabe1af47e5020ef1 (MD5) Previous issue date: 2011 / Resumo: O comportamento dinâmico em unidades de produção de óleo é muito importante para a operação e projeto de equipamentos. O desenvolvimento da tecnologia no processamento primário de petróleo é caracterizado pela otimização de peso e espaço nas unidades de produção. Estas restrições têm sido diretrizes para pesquisas em desenvolvimento de equipamentos mais eficientes e compactos, como hidrociclones. Porém, esta capacidade de compactar equipamentos resultou em redução na flexibilidade em operar com oscilações de carga (golfadas). Ao longo dos últimos anos, a maturação de campos produtores e o aumento na produção de água e no uso de gás lift associados à produção de óleo em lâminas d'água cada vez mais profundas têm aumentado a freqüência de golfadas. A simulação dinâmica pode ser utilizada para desenvolver estratégias para controlar situações transientes em plataformas offshore. Este trabalho utilizou a simulação dinâmica de uma planta de condicionamento de gás natural em plataforma offshore feita no simulador de processos HYSYS 7.2, como ferramenta para analisar a planta e propor melhores condições de operação. Neste trabalho duas situações serão analisadas. Na primeira, apenas o gás associado passa pelo sistema de compressão e o gás não associado é encaminhado diretamente para desidratação com TEG (situação 1). Na segunda, haverá uma quebra de pressão do gás proveniente dos poços de gás e este deverá ser encaminhado para o sistema de compressão juntamente com o gás proveniente dos poços de óleo (situação 2). Em um primeiro momento, a planta foi analisada em modelo de estado estacionário e foi avaliado o efeito da quebra de pressão na temperatura da tubulação à jusante das válvulas responsáveis pela quebra (situação 2). Em um segundo momento, a planta foi avaliada no estado dinâmico, onde foi possível analisar o efeito que as oscilações de carga têm no sistema de compressão da planta, bem como nas trocas térmicas. Este segundo estudo foi avaliado para as situações 1 e 2. Para o estudo em estado estacionário, foi possível observar que a especificação de temperatura mínima de projeto para a tubulação à jusante das válvulas que efetuam a quebra de pressão não é alcançada, porém, existe uma faixa de ?P ideal para cada válvula a fim de evitar a formação de gelo na parte externa da tubulação. Para o estudo dinâmico foi possível avaliar os efeitos que as oscilações de carga trazem para o sistema de compressão e em que situação (1 ou 2) a planta opera com maior estabilidade. Verificou-se que o trocador da saída do sistema de compressão opera com certa instabilidade na situação 1 devido à baixa vazão de gás a ser resfriado e na situação 2 esta instabilidade é reduzida. As conclusões deste estudo mostram a importância da simulação dinâmica como ferramenta de decisão para o engenheiro de processamento de gás na operação da planta / Abstract: Dynamic behavior in oil production units is vital for equipments project and operation. Technology development in offshore primary processing has traditionally been characterized by optimizing weight and space in their production units. Such restrictions have been the guidelines for researches in developing more efficient and compact equipments, such as hydro cyclones. However, this compactness has resulted, invariably, in reduced capacity to deal with load oscillations, typical in offshore units. Along the last years the maturation of production fields, and the increase of water production and gas lift use, associated to the oil production in larger and larger water depths have been increasing slugs intensity. Dynamic simulation can be used to develop better strategies to control transient situations in offshore units. This study use a dynamic simulation of a natural gas offshore conditioning plant as a tool to analyze the plant and to propose better operational conditions. The process simulator to do dynamic simulation was HYSYS 7.2. In this work two situations were analyzed. In the first one, only the gas from oil wells pass through the gas compression system and the gas from gas wells are forwarded directly to dehydration with TEG (situation 1). In the second situation, there will be a pressure drop of the gas from gas wells and this gas should be forwarded to the compression system along with gas from oil wells (situation 2). At first, the plant was analyzed in steady state model and the effect of pressure drop in pipe temperature downstream of the valves responsible for pressure drop was evaluated (situation 2). In a second stage the plant was evaluated in dynamic state where it was possible to analyze the effect of load oscillations in the compression system, as well as in the heat exchange. This second study was evaluated for situations 1 and 2. For the static study, the specification of minimum project temperature for the pipeline downstream of the valves that perform the pressure drop is not achieved but there is an ideal range pressure drop for each valve to prevent ice formation outside the pipe. In the dynamic study was evaluated the effects of load oscillations in compression system and in what situation (1 or 2) the plant operates with greater stability. It was found that the heat exchange of the output of the compression system operates with instability in the situation 1 due to the low flow of gas to be cooled, and in the situation 2 this instability is reduced. The conclusions of this study show the importance of dynamic simulation as a decision tool for the engineer in the gas processing plant operation / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Abstract This thesis focuses on advanced multi-antenna receiver and transmission techniques to improve the utilization efficiencies of radio resources in broadband single carrier communications. Special focus is devoted to the development of computationally efficient frequency domain (FD) turbo equalization techniques for single and multiuser MIMO frequency selective channels. Another special emphasis is given to transmission power optimization for single user MIMO communications, which takes into account the convergence properties of the iterative equalizer. A new iterative FD soft cancellation (SC) and minimum mean square error (MMSE) filtering based joint-over-antenna (JA) multiuser MIMO signal detection technique for multiuser MIMO uplink transmission in frequency-selective channels is proposed. The proposed FD multiuser MIMO detection technique requires significantly lower computational complexity than its time-domain counterpart. Furthermore, significant performance gains can be achieved with the proposed JA turbo receiver compared to an antenna-by-antenna (AA) turbo receiver when the total number of transmitter antennas and users is larger than the number of receiver antennas, as well as in the presence of spatial correlation. The impact of existing linear precoding techniques, e.g, maximum information rate (MaxRate) and minimum sum mean square error (MinSumMSE), on the performance of frequency domain turbo equalization is investigated by utilizing extrinsic information transfer (EXIT) chart analysis. A novel transmission power minimization framework based on an EXIT analysis of single carrier MIMO transmission with iterative FD SC-MMSE equalization is then proposed. The proposed optimization framework explicitly takes into account the convergence properties of the iterative equalizer. The proposed convergence constrained power allocation (CCPA) technique decouples the spatial interference between streams using singular value decomposition (SVD), and minimizes the transmission power while achieving the mutual information target for each stream after iterations at the receiver side. The transmission power allocation can be formulated as a convex optimization problem. A special case having only two mutual information constraints is considered, for which the Lagrange dual function is derived and its dual problem is solved. Inspired by the Lagrange duality, two CCPA based heuristic schemes are developed. The numerical results demonstrate that the proposed CCPA schemes outperform the existing power allocation schemes. / Tiivistelmä Tässä työssä tutkitaan edistyksellisten moniantennivastaanotto- ja lähetysmenetelmien käyttöä radioresurssien tehokkuuden parantamiseen laajakaistaisessa yhden kantoaallon kommunikaatiossa. Työssä keskitytään erityisesti laskennallisesti tehokkaiden taajuustasossa suoritettavien iteratiivisten kanavakorjaintekniikoiden kehittämiseen yhden ja usean käyttäjän multiple-input multiple-output (MIMO) -kommunikaatiossa taajuusselektiivisen radiokanavan yli. Toinen tutkimuksen painopiste on lähetystehon optimointi yhden käyttäjän MIMO-kommunikaatiossa, jossa iteratiivisen kanavakorjaimen konvergenssiominaisuudet otetaan huomioon. Työssä ehdotetaan uudenlaista iteratiivista taajuustasossa suoritettavaa soft-cancellation (SC) ja minimum mean square error (MMSE) -suodatukseen pohjautuvaa joint-over-antenna (JA) monen käyttäjän ilmaisumenetelmää nousevan siirtokanavan tiedonsiirtoon taajuusselektiivisessa radiokanavassa. Ehdotettu tajuustasossa suoritettava usean käyttäjän MIMO-lähetyksen ilmaisumenetelmä vaatii selvästi vähemmän laskentatehoa verrattuna aikatason menetelmään. Tämän lisäksi ehdotetulla menetelmällä voidaan saavuttaa merkittävää suorituskykyhyötyä verrattuna antenna-by-antenna (AA) -pohjaiseen iteratiiviseen vastaanottimeen kun lähetysantennien ja käyttäjien kokonaislukumäärä on suurempi kuin vastaanotinantennien. Suorituskykyhyöty pätee myös tilakorrelaation tapauksessa. Työssä tutkitaan lisäksi olemassa olevien lineaaristen esikoodaustekniikoiden, esim. maximum information rate (MaxRate) and minimum sum mean square error (MinSumMSE), vaikutusta taajuustasossa suoritettavaan iteratiivisen kanavakorjaimen konvergenssiominaisuuksiin xtrinsic information transfer (EXIT) -analyysin avulla. Työssä ehdotetaan uudenlaista EXIT-analyysi-pohjaista lähetystehon minimointimenetelmää yhden kantoaallon MIMO-lähetykseen käyttäen iteratiivista taajuustason SC-MMSE-kanavakorjainta. Menetelmä ottaa huomioon iteratiivisen kanavakorjaimen konvergenssiominaisuudet. Ehdotettu convergence constrained power allocation (CCPA) -menetelmä erottaa tilatason häiriön lähetteiden välillä hyödyntäen singular value decomposition (SVD) -tekniikkaa ja minimoi lähetystehon ja saavuttaa samalla keskinäisinformaatiotavoitteet jokaiselle lähetteelle iteraatioiden jälkeen vastaanottimessa. Lähetystehon minimointiongelma voidaan muotoilla konveksiksi optimointiongelmaksi. Kahden keskinäisinformaatiorajoitteen erityistapaukselle johdetaan Lagrangen duaalifunktio ja ratkaistaan sen duaalifunktio. Työssä kehitetään lisäksi kaksi CCPA-pohjaista heuristista menetelmää. Numeeriset tulokset osoittavat ehdotettujen CCPA-pohjaisten menetelmien suoriutuvan paremmin verrattuna olemassa oleviin menetelmiin.

Abstract High computational complexity constrains truly exhaustive computer searches for good space-time (ST) coded modulations mostly to low constraint length space-time trellis codes (STTrCs). Such codes are primarily devised to achieve maximum transmit diversity gain. Due to their low memory order, optimization based on the design criterion of secondary importance typically results in rather modest coding gains. As another disadvantage of limited freedom, the different low memory order STTrCs are almost exclusively constructed for either slow or fast fading channels. Therefore in practical applications characterized by extremely variable Doppler frequencies, the codes typically fail to demonstrate desired robustness. On the other hand, the main drawback of eventually increased constraint lengths is the prohibitively large decoding complexity, which may increase exponentially if optimal maximum-likelihood decoding (MLD) is applied at the receiver. Therefore, robust ST coded modulation schemes with large equivalent memory orders structured as to allow sub-optimal, low complexity, iterative decoding are needed. To address the aforementioned issues, this thesis proposes parallel concatenated space-time turbo coded modulation (STTuCM). It is among the earliest multiple-input multiple-output (MIMO) coded modulation designs built on the intersection of ST coding and turbo coding. The systematic procedure for building an equivalent recursive STTrC (Rec-STTrC) based on the trellis diagram of an arbitrary non-recursive STTrC is first introduced. The parallel concatenation of punctured constituent Rec-STTrCs designed upon the non-recursive Tarokh et al. STTrCs (Tarokh-STTrCs) is evaluated under different narrow-band frequency flat block fading channels. Combined with novel transceiver designs, the applications for future wide-band code division multiple access (WCDMA) and orthogonal frequency division multiplexing (OFDM) based broadband radio communication systems are considered. The distance spectrum (DS) interpretation of the STTuCM and union bound (UB) performance analysis over slow and fast fading channels reveal the importance of multiplicities in the ST coding design. The modified design criteria for space-time codes (STCs) are introduced that capture the joint effects of error coefficients and multiplicities in the two dimensional DS of a code. Applied to STTuCM, such DS optimization resulted in a new set of constituent codes (CCs) for improved and robust performance over both slow and fast fading channels. A recursive systematic form with a primitive equivalent feedback polynomial is assumed for CCs to assure good convergence in iterative decoding. To justify such assumptions, the iterative decoding convergence analysis based on the Gaussian approximation of the extrinsic information is performed. The DS interpretation, introduced with respect to an arbitrary defined effective Hamming distance (EHD) and effective product distance (EPD), is applicable to the general class of geometrically non-uniform (GNU) CCs. With no constrains on the implemented information interleaving, the STTuCM constructed from newly designed CCs achieves full spatial diversity over quasi-static fading channels, the condition commonly identified as the most restrictive for robust performance over a variety of Doppler spreads. Finally, the impact of bit-wise and symbol-wise information interleaving on the performance of STTuCM is studied.

In this dissertation the aim was to investigate the usage of algorithms found in computer science and apply suitable algorithms to the problem of decoding multiple-input multipleoutput (MIMO) space-time-frequency block coded signals. It was found that the sphere decoder is a specific implementation of the A* tree search algorithm that is well known in computer science. Based on this knowledge, the sphere decoder was extended to include a priori information in the maximum a posteriori probability (MAP) joint decoding of the STFC block coded MIMO signals. The added complexity the addition of a priori information has on the sphere decoder was investigated and compared to the sphere decoder without a priori information. To mitigate the potential additional complexity several algorithms that determine the order in which the symbols are decoded were investigated. Three new algorithms incorporating a priori information were developed and compared with two existing algorithms. The existing algorithms compared against are sorting based on the norms of the channel matrix columns and the sorted QR decomposition. Additionally, the zero forcing (ZF) and minimum mean squared error (MMSE) decoderswith and without decision feedback (DF) were also extended to include a priori information. The developed method of incorporating a priori information was compared to an existing algorithm based on receive vector translation (RVT). The limitation of RVT to quadrature phase shift keying (QPSK) and binary shift keying (BPSK) constellations was also shown in its derivation. The impact of the various symbol sorting algorithms initially developed for the sphere decoder on these decoders was also investigated. The developed a priori decoders operate in the log domain and as such accept a priori information in log-likelihood ratios (LLRs). In order to output LLRs to the forward error correcting (FEC) code, use of the max-log approximation, occasionally referred to as hard-to-soft decoding, was made. In order to test the developed decoders, an iterative turbo decoder structure was used together with an LDPC decoder to decode threaded algebraic space-time (TAST) codes in a Rayleigh faded MIMO channel. Two variables that have the greatest impact on the performance of the turbo decoder were identified: the hard limit value of the LLRs to the LDPC decoder and the number of independently faded bits in the LDPC code. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / unrestricted

In spread spectrum systems employing parity bit selected spreading sequences, parity bits generated from a linear block encoder are used to select a spreading code from a set of mutually orthogonal spreading sequences. In this thesis, turbo receivers for SS-PB systems are proposed and investigated. In the transmitter, data bits are rst convolutionally encoded before being fed into SS-PB modulator. In fact, the parity bit spreading code selection technique acts as an inner encoder in this system without allocating any transmit energy to the additional redundancy provided by this technique. The receiver implements a turbo processing by iteratively exchanging the soft information on coded bits between a SISO detector and a SISO decoder. In this system, detection is performed by incorporating the extrinsic information provided by the decoder in the last iteration into the received signal to calculate the likelihood of each detected bit in terms of LLR which is used as the input for a SISO decoder. In addition, SISO detectors are proposed for MC-CDMA and MIMO-CDMA systems that employ parity bit selected and permutation spreading. In the case of multiuser scenario, a turbo SISO multiuser detector is introduced for SS-PB systems for both synchronous and asynchronous channels. In such systems, MAI is estimated from the extrinsic information provided by the SISO channel decoder in the previous iteration. SISO multiuser detectors are also proposed for the case of multiple users in MC-CDMA and MIMO-CDMA systems when parity bit selected and permutation spreading are used. Simulations performed for all the proposed turbo receivers show a signi cant reduction in BER in AWGN and fading channels over multiple iterations.

Crack initiation and propagation in the bladed disks of aero-engines caused by high-cycle fatigue under cyclic loads could result in the breakdown of the engines if not detected at an early stage. Although a number of fault detection methods have been reported in the literature, it still remains very challenging to develop a reliable online technique to accurately diagnose defects in bladed disks. One of the main challenges is to characterize signals contaminated by noises. These noises caused by very dynamic engine operation environment. This work presents a new technique for engine bladed disk crack detection, which utilizes advanced analysis of clearance and time-of-arrival signals acquired from blade tip sensors. This technique involves two stages of signal processing: 1) signal pre-processing for noise elimination from predetermined causes; and 2) signal post-processing for characterizing crack initiation and location. Experimental results from the spin rig test were used to validate technique predictions.

The HF band of radio frequencies, from 3-30 MHz, is unique in its property that it is refracted by the ionosphere. This property allows long distance radio telecommunications around the world without requiring infrastructure. High frequency (HF) communication has been largely superseded by satellite and cellular technologies for day-to-day communications, due to the tight bandwidth constraints and technical difficulties inherent in using it. However there is still a need for HF communications devices where existing infrastructure is not available, such as in remote or polar locations, or in emergency situations due to natural disasters. This research is aimed at the development of an asymmetric HF communications link, with a battery-powered remote unit that transmits a small amount of data to a mains-powered base station. New technologies are identified and evaluated for use in the link, with the aim of reducing the power requirements of the remote unit. Error correction techniques are investigated. Low-density parity check (LDPC) codes, which are powerful codes used for forward error correction, are suggested for use in the link. Quasi-cyclic LDPC codes allow the low-power transmitter unit to use a computationally simple encoder based on feedback shift registers for generating the LDPC block codes cheaply. Semi-blind LDPC turbo equalisation is a powerful technique that can be used at the base station which utilises the structure of the LDPC code to encode the data stream. This equalises a received signal with a minimal amount of training data required, reducing the duty cycle of the remote unit. Hybrid automatic repeat request (HARQ) techniques are also investigated, which increase the throughput of a link when data repeats are required. A novel HARQ techniquewas created and proven to increase throughput in links with noise. As the proposed system may be deployed in remote locations, or locations where it might be difficult or undesirable to erect a proper HF antenna, a selection of buried antennas are characterised. A design for a remote unit is suggested. This unit was manufactured and used to test the capability of inexpensive, low power hardware to implement the proposed remote unit algorithms.

Obsahem této diplomové práce byla vhodnost využití turbodmychadla s přidruženým motor-generátorem pro vybrané typy hybridních vozidel a následná analýza energetických toků pro danou motorovou aplikaci. Přístup prezentovaný v práci zahrnuje termodynamický model motoru v programu GT-SUITE ve kterém jsou zkoumány možnosti energetických toků při změně velikost turbínového a kompresorového kola turbodmychadla. Přistup je aplikován na turbodmychadlo s variabní geometrií lopatek s přidruženým motor generátorem pro donáškové vozidlo, kde je možné při různých zatíženích motoru rekuperovat energii z turbodmychadla. Zároveň byli zjištěny možnosti snížení spotřeby paliva v určitých provozních bodech motoru.

This thesis builds on previous work on an Institute of Roads FAST VUT dealing with modifications of road I/43 Brno – Svitavy. A conversion of the existing temporary three leg single lane roundabout to egg turbo roundabout with four legs, is proposed there, in accordance with local plan of Lipůvka. The intersection of road I/43 and II/379 can be characterized by large congestions in the morning peak hours during weekdays and afternoon peak hours on Saturday and Sunday. That is the reason for implementation of capacity assessment of designed turbo roundabout and comparison with current situation. Construction of fourth leg is motivated by the planned expansion of residential area and the development of industrial zone on the south-western outskirts of the village and rerouting of the county road II/379 out of built-up area as well. Road I/43 is an important thoroughfare north of Brno, so it is obvious effort to eliminate the bottlenecks on the route. The thesis also includes a theoretical introduction dealing with the design of turbo roundabouts abroad.

The aim of this Master's thesis is design of possible modifications of crossroad I/55 and II/432, primarily with focus on capacity and safety. The first part of this thesis is dealing with measurement and evaluation of current traffic intensities, and capacity calculations of suggested design modifications. The second part of the thesis consists of detailed project of one design modification (diamond interchange) for documentation for construction permit.