Tem sido observado, de longa data, que ensaios de carregamento dinâmico e provas de carga estática realizados em estacas cravadas após diferentes intervalos de tempo da cravação mostram que podem ocorrer variações nas suas capacidades de carga ao longo do tempo, que em certos casos levam ao aumento da resistência do solo e em outros casos resultam na diminuição da resistência do solo. O trabalho apresenta uma revisão bibliográfica do fenômeno de ganho, com o tempo, de resistência de estacas cravadas em solos argilosos conhecido por efeito \"set-up\", cujos principais mecanismos são explicados por teorias relacionadas à variação das pressões neutras, geradas ao redor das estacas durante a cravação. O método adotado nas análises envolve conceitos da teoria da expansão da cavidade cilíndrica, onde o objetivo principal é entender o comportamento de estacas cravadas em solos argilosos, nos quais o efeito \"set-up\" é normalmente mais acentuado. Os fenômenos pertinentes são avaliados através de análises teóricas, usando o método de Randolph, e numéricas, recorrendo ao método dos elementos finitos. Estas análises foram validadas através de modelagens numéricas comparadas a dados de campo apresentados por ETC (Earth Technology Corporation), sendo observada boa aderência entre os dados de campos e os resultados das estimativas teóricas. A aplicação desta metodologia permite estimar variações tanto das tensões radiais efetivas quanto dos atritos laterais unitários em função do tempo, levando em conta dois parâmetros mais relevantes, a saber, resistência não-drenada e coeficiente de adensamento primário horizontal. Comparações são feitas a ensaios de carregamento dinâmico realizados em estacas cravadas em uma obra da Baixada Santista (SP). Os resultados obtidos mostram uma dispersão no ganho das resistências das estacas analisadas, mas com variações dentro de uma faixa de valores relativamente estreita. Além disso, revelam valores teóricos de \"set-up\", relativo a parcela de atrito lateral, em um intervalo entre 2,0 e 2,5 aproximadamente, 20 dias após a cravação. Apesar das dispersões encontradas, inerentes a este tipo de estudo, considera-se que os resultados obtidos significam um importante passo para melhor entendimento do efeito \"set-up\". / For a long time, it has been observed that load tests performed on driven piles show that there may be variations in load capacity over time, which in some cases lead to an increase in soil resistance and in other cases result in decrease of soil resistance. In this study, a review is presented about the mechanisms that lead to the gains in pile load capacity with time, known as \"set-up\", whose main mechanisms are explained by theories related to the excess porepressures generated around the piles during installation. The presented method involves the theory of cylindrical cavity expansion, where the main objective is to understand the behavior of driven piles in clayey soils, in which \"Set-up\" is usually more pronounced. The relevant phenomena are evaluated by theoretical analysis, based in Randolph\'s method, and numerical analysis, using the finite element method. These analyzes were validated through numerical analysis compared to field data presented by ETC (Earth Technology Corporation). Good agreement has been observed between field data and the theoretical results. The methodology allows to estimate variations in both the effective radial stress and the unit friction resistance over time, considering two main parameters, undrained shear strength and horizontal coefficient of consolidation. Comparisons are made to dynamic load tests conducted on driven piles located in Santos Coastal Plane (\"Baixada Santista\"), in São Paulo - Brazil. A dispersion in the results of the load capacities has been observed, but within a relatively narrow range of values. In adittion, the theoretical values of lateral \"set-up\" were obtained in a range between 2,0 and 2,5 approximately 20 days after installation. Knowing that dispersions are inherent to this type of study, it is considered that the results imply an important step to a better understanding of the \"set-up\".

Made available in DSpace on 2015-04-22T22:11:22Z (GMT). No. of bitstreams: 1 Alberjan.pdf: 1648406 bytes, checksum: e7cc01faadea0adae547a7958b75ccce (MD5) Previous issue date: 2011-07-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work was aimed at applying the tools of the PRS System (Lean Production), whose primary tool was crafted VSM (Value Stream Mapping), a process known as SMT (Surface Mount Technology). Principles for lean production, eliminating waste and creating value stream in a real situation through kaizen events, were used to obtain results of this application, showing a lean transformation, with significant reductions in waste generated in the process. The study period was eight months into a private company located in PIM, where through the use of tools of this system and methodology of action research, it was possible to identify the critical process - setup - where focused improvement actions. With the change in the system setup, the standard work and creating a setup program using visual aid, favoring the continuous flow in this process. During the research, trainings were conducted in the factory with the operators, leaders, supervisors and engineers responsible, who participated actively in the improvement actions. Therefore, through value stream mapping, we propose to draw the current state of the stream, offering a future state, identifying and eliminating everything does not add value. To quantify the increase in productivity on the factory floor and total earnings of areas in the factory. / Este trabalho teve como objetivo a aplicação das ferramentas do Sistema de Produção Enxuta (SPE), cuja principal ferramenta trabalhada foi o Mapeamento da cadeia de valor (VSM), num processo denominado Tecnologia em Montagem de Superfície (SMT). Princípios que regem a produção enxuta, eliminação de desperdícios e a criação do fluxo de valor em uma situação real, através de eventos kaizen, foram utilizados para a obtenção de resultados dessa aplicação, evidenciando uma transformação enxuta, com expressivas reduções dos desperdícios gerados no processo. O período da pesquisa foi de oito meses em uma empresa privada situada no PIM, onde por meio da utilização de ferramentas desse sistema e a metodologia da pesquisa-ação, foi possível identificar o processo crítico setup para onde se concentraram as ações de melhorias. Com a mudança na sistemática de setup, no trabalho padronizado e criação de um setup programado, utilizando indicações visuais, favorecendo o fluxo contínuo nesta cadeia produtiva. No desenvolvimento da pesquisa, foram realizados treinamentos in loco com os operadores, líderes, supervisores e os engenheiros responsáveis, os quais participavam ativamente nas ações de melhoria. Portanto, através do mapeamento da cadeia de valor, propõem-se desenhar o estado atual da cadeia, propondo um estado futuro, identificando e eliminando aquilo que não agrega valor. Com isso, quantificar o aumento na produtividade no chão de fábrica e ganhos totais de áreas na fábrica.

Until recently, there had been a gap between the output frequencies of electronic and optical sources, which included waves of frequencies around 300 GHz to 3 THz and was known as the Terahertz gap. After the development of sources and detectors that operated at these frequencies, Terahertz radiation began to find its way through a variety of applications such as surveillance, spectroscopy and medical imaging. Terahertz radiation has been used in medical imaging experiments on different in-vitro and some in-vivo biological tissues and has shown promising results in differentiating certain features in those tissues. Moreover, it has demonstrated well in detecting certain polar molecules due to these molecules’ fingerprint in Terahertz range of frequencies. Considering these facts, Terahertz has been proved to have the potential for being a perspective medical imaging method, which can be used as a complement to other imaging techniques such as MRI or X-ray or even as a separate method. Due to the capacity of Terahertz radiation, much research is being done on using Terahertz generation-detection set-ups for medical imaging and improving the imaging parameters of these set-ups to capture more precise and meaningful images. In this thesis, the imaging parameters of two different THz imaging set-ups have been studied and compared. One of these imaging set-ups is a THz pulse set-up with photoconductive dipole antennas as source and detector and the other one is a continuous-wave set-up with a backward wave oscillator as the source and a Golay cell as the detector. To the best of our knowledge, a comparative analysis of the imaging parameters of these two types of THz imaging set-ups has not been performed previously. In this thesis, parameters such as modulation transfer function (MTF), resolution and beam profile have been measured through the experiments, for both the THz pulse and THz CW imaging set-ups. These results are compared to the results obtained by theoretical formulas and the reason for any differences occurred between these two results has been explained. Moreover, the imaging parameters found from the experiments for the two set-ups have been compared together and similarities and differences have been discussed. In this thesis, a set of experiments has also been done to verify the capability of the two imaging set-ups for in-vitro tooth imaging, towards developing THz imaging systems suitable for clinical imaging application. These experiments have been performed on a tooth crown sample with the pulse set-up and on a tooth cross-section sample with the continuous-wave set-up. The capability of our THz pulse imaging system to distinguish thickness variations in a tooth crown sample by time-of-flight imaging has been shown and discussed.

Until recently, there had been a gap between the output frequencies of electronic and optical sources, which included waves of frequencies around 300 GHz to 3 THz and was known as the Terahertz gap. After the development of sources and detectors that operated at these frequencies, Terahertz radiation began to find its way through a variety of applications such as surveillance, spectroscopy and medical imaging. Terahertz radiation has been used in medical imaging experiments on different in-vitro and some in-vivo biological tissues and has shown promising results in differentiating certain features in those tissues. Moreover, it has demonstrated well in detecting certain polar molecules due to these molecules’ fingerprint in Terahertz range of frequencies. Considering these facts, Terahertz has been proved to have the potential for being a perspective medical imaging method, which can be used as a complement to other imaging techniques such as MRI or X-ray or even as a separate method. Due to the capacity of Terahertz radiation, much research is being done on using Terahertz generation-detection set-ups for medical imaging and improving the imaging parameters of these set-ups to capture more precise and meaningful images. In this thesis, the imaging parameters of two different THz imaging set-ups have been studied and compared. One of these imaging set-ups is a THz pulse set-up with photoconductive dipole antennas as source and detector and the other one is a continuous-wave set-up with a backward wave oscillator as the source and a Golay cell as the detector. To the best of our knowledge, a comparative analysis of the imaging parameters of these two types of THz imaging set-ups has not been performed previously. In this thesis, parameters such as modulation transfer function (MTF), resolution and beam profile have been measured through the experiments, for both the THz pulse and THz CW imaging set-ups. These results are compared to the results obtained by theoretical formulas and the reason for any differences occurred between these two results has been explained. Moreover, the imaging parameters found from the experiments for the two set-ups have been compared together and similarities and differences have been discussed. In this thesis, a set of experiments has also been done to verify the capability of the two imaging set-ups for in-vitro tooth imaging, towards developing THz imaging systems suitable for clinical imaging application. These experiments have been performed on a tooth crown sample with the pulse set-up and on a tooth cross-section sample with the continuous-wave set-up. The capability of our THz pulse imaging system to distinguish thickness variations in a tooth crown sample by time-of-flight imaging has been shown and discussed.

Productivity advances generated from ‘lean manufacturing’ are self–evident. Plants that adopt ‘lean’ are more capable of achieving shorter lead times, less waste in the system and higher quality levels. The goal of this study was to ascertain which ‘lean’ tools and techniques are available for use. A matrix was constructed with a summation of the authors who agree that specific ‘lean’ tools will reduce cycle time. It was found that reduced set–up time and waste elimination are most affected by the implementation of ‘lean’ tools and techniques. An empirical study was conducted to confirm the results of the literature study. The respondents’ knowledge on the ‘lean’ tools was also tested. It was found that respondents have a sound understanding of set–up time; they agree that it must be reduced in the plant. Pre–scientific evidence and the response from the empirical study confirm that there is a substantial amount of waste in the factory. A current state value–stream map was drawn from a single welded part Product X. The value–stream was analysed to reduce the cycle time in the process, with the focus on set–up time reduction and waste elimination. The future state value–stream map was drawn, displaying astonishing results. A continuous improvement (kaizen) programme will help reduce the cycle time even further by making use of the other ‘lean’ tools discussed in this study. This programme forms part of the procedure to optimise cycle time. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.

Productivity advances generated from ‘lean manufacturing’ are self–evident. Plants that adopt ‘lean’ are more capable of achieving shorter lead times, less waste in the system and higher quality levels. The goal of this study was to ascertain which ‘lean’ tools and techniques are available for use. A matrix was constructed with a summation of the authors who agree that specific ‘lean’ tools will reduce cycle time. It was found that reduced set–up time and waste elimination are most affected by the implementation of ‘lean’ tools and techniques. An empirical study was conducted to confirm the results of the literature study. The respondents’ knowledge on the ‘lean’ tools was also tested. It was found that respondents have a sound understanding of set–up time; they agree that it must be reduced in the plant. Pre–scientific evidence and the response from the empirical study confirm that there is a substantial amount of waste in the factory. A current state value–stream map was drawn from a single welded part Product X. The value–stream was analysed to reduce the cycle time in the process, with the focus on set–up time reduction and waste elimination. The future state value–stream map was drawn, displaying astonishing results. A continuous improvement (kaizen) programme will help reduce the cycle time even further by making use of the other ‘lean’ tools discussed in this study. This programme forms part of the procedure to optimise cycle time. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.

Advertisers setting up search engine advertising campaigns for the first time need to place bids on keywords, but typically lack experience and data to determine ranks that maximize a keyword's profit (generally referred to as a cold-start problem). This article aims at solving the problem of bidding on keywords in newly set-up search engine advertising campaigns. We suggest that advertisers collect data from the Google Keyword Planner to obtain precise estimates of the percentage increases in prices per click and clickthrough rates, which are needed to calculate optimal bids (exact approach). Together with the profit contribution per conversion and the conversion rate, the advertiser might then set bids that maximize profit. In case advertisers cannot afford to collect the required data, we suggest two proxy approaches and evaluate their performance using the exact approach as a benchmark. The empirical study shows that both proxy approaches perform reasonably well-the easier approach to implement (proxy 2) sometimes performs even better than the more sophisticated one (proxy 1). As a consequence, advertisers might just use this very simple proxy when bidding on keywords in newly set-up SEA campaigns. This research extends the stream of literature on how to determine optimal bids, which so far focuses on campaigns that are already running and where the required data to calculate bids is already available. This research offers a novel approach of determining bids when advertisers lack the aforementioned information.

Moelven är en av Skandinaviens största trämekaniska koncerner med 52 operativa enheter i Norge, Sverige och Danmark. Denna studie har utförts i hyvlerianläggningen hos Moelven Valåsen Wood AB som är ett hyvleri och vidareförädling av byggvirke beläget i Karlskoga. Problemet grundar sig i att Moelven vill öka utnyttjandegraden i hyvlerianläggningen. Denna ligger idag på ca 65% och hyvleriet begränsar därför en stor del av materialflödet. Syftet med denna fallstudie var att undersöka vilka orsaker som ligger bakom den låga utnyttjandegraden för att ge förslag på åtgärder till dessa. Studien inleddes med ett brett perspektiv för att kunna undersöka de verkliga orsakerna till problemet. En analys gjordes av de olika stopporsakerna för att klargöra vilka olika stopp som uppstår samt hur stor del av den totala stopptiden de utgör. Vidare gjordes avgränsningar som innebar en fördjupning inom omställningsprocessen då omställningar av hyveln utgjorde 30% av den totala stopptiden under tidsperioden. För att kunna analysera denna process gjordes videoinspelningar där de olika arbetsmomenten definierades och tidsattes. Då fräsbyten var de omställningar som observerades flest antal gånger utformades konkreta förbättringsförslag främst för dessa. Moelven får även underlag för att kunna gå vidare med de övriga omställningarna. Fallstudien resulterade i olika förbättringsförslag som främst syftade till att effektivisera omställningarna. Dessa förslag innebar: • Separera externa och interna aktiviteter, såsom att förbereda verktyg inför omställningen. • Använda verktygsvagnar för att eliminera rörelser i så stor utsträckning som möjligt. • Skapa bättre ordning på verktyg genom att utforma en check table. • Standardisering av arbetsmoment genom att skapa en rutinbeskrivning samt dela upp  operatörerna i olika arbetsroller. • Involvera alla i organisationen för att kunna arbeta med ständiga förbättringar. En simulering gjordes genom att implementera delar av förbättringsförslaget vilken medförde en ställtidsreducering om 32.5% för fräsbyte. Då en stor gemensam faktor för alla typer av omställningar är rörelser, vilket förbättringsförslaget syftar till att reducera kan det antas vara generaliserbart för övriga omställningar. / Moelven is an industrial group that produces building materials and systems for the construction industry; with its 52 productions units in Norway, Sweden and Denmark, it is one of the biggest in Scandinavia. This study has been carried out in the planing mill at Moelven Valåsen Wood AB in Karlskoga. Because of the low utilization rate in the planing mill (65%), it constitutes a bottleneck, meaning it limits the capacity and flow of material, for most of the products. The purpose of the study was to analyze the stoppage in the planing mill in order to make recommendations on how the utilization rate can be increased. The study began with a wide perspective to identify the reasons behind this problem. A summary of all stops in the planing mill concluded that set ups of the planer made up for 30% of total stoppage. Because of this, the study was narrowed down to mainly analyze the different types of set ups, which was done through extensive observations and videotaping. The solutions and recommendations that were given are therefore almost entirely regarding set up-time reduction, and more specifically, milling set ups. The recommendations, based on the results of the study, includes: • Suggestions on how to separate internal and external set up. • Better order of tools through designing a check table. • Standardizing the procedure by creating a routine and dividing the operators into different work roles. • Involving everyone in the organization in order to work with continuous improvement. A simulation of milling set ups was done by implementing parts of the recommendations – this resulted in a setup up-time reduction of 13 minutes, which corresponds to 32.5%. Because of common denominators, such as movements, the recommendations given are likely generalizable for all set ups.

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