Made available in DSpace on 2016-06-02T19:16:33Z (GMT). No. of bitstreams: 1 4769.pdf: 3109434 bytes, checksum: db9c66ec06b2b5377f3c0f675f040eac (MD5) Previous issue date: 2010-08-20 / Either by environmental, economical, technological or social reasons, the total mechanization of field operations in the cultivation of sugar cane has already been a reality in the sugar cane plantations in Sao Paulo state in which the harvesting operations (mainly cuts) performed by the man beforehand are being systematically replaced by machines, trying to match productivity with sustainability and the development of the field and the city. Within this scenario, the market for machinery and agricultural implements for the harvesting of the sugar cane has grown, but some technological barriers have been identified as effective for the advancement of the mechanization in the harvest of sugar cane: 1) the cleaning system of stems that according to experts, does not promote an efficient cleaning, taking to the plant impurities that compromise the production, 2) the size of the machines, which does not meet the needs of the small and medium producers (the biggest number in the country), 3) a decrease in the weight of the machines, trying to reduce the soil compaction; 4) harvest in several rows (today the harvest is done in the most two rows) to reduce costs of the operation. This work is a result of the research in patent documents to know and to prospect the current state of technological systems for collection, focusing mainly the system of mechanized harvesting of sugar cane and especially the sub-cutting system, building technological indicators to contribute with the advancement of the set of solutions for the accomplishment of the agricultural harvest of the cane. The methodology used in this work was the bibliography in patent documents, in the database Derwent Innovations Index. It was developed using a search expression CIP and the keywords to limit the universe of research in which 587 patent records deemed as relevant were recovered. After processing the data in Infotrans, they were treated with the VantagePoint software which crossed the data and created thesaurus, allowing some inferences. The results identified some scenarios that show the boundaries of the technology in harvesting the sugar cane. It was also possible to identify the countries and the companies that place more patents, and to identify which countries have been trying to use the technology for the mechanization of the harvest. An example is China with a significant participation since 2005 in number of applications for patents. Therefore, it was possible to draw some scenarios that are best explained in Chapter 4: relating to the results achieved. / Seja por questões legais, ambientais, econômicas, tecnológicas ou sociais a mecanização total das operações de campo, no cultivo da cana-de-açúcar, é uma realidade que já se pode observar nos canaviais paulistas onde as operações de colheita (principalmente o corte) que eram realizadas pelo homem vêm sendo, sistematicamente, substituídas por máquinas; buscando aliar produtividade com sustentabilidade para o desenvolvimento do campo e da cidade. Dentro desse cenário, o mercado de máquinas e implementos agrícolas para a colheita da cana-de-açúcar encontra-se aquecido, porém, algumas barreiras tecnológicas são apontadas, na literatura, como entrave para o avanço efetivo da mecanização da colheita da cana-de-açúcar: 1) o sistema de limpeza de colmos que, segundo especialistas, não promovem uma limpeza eficiente levando para a usina muitas impurezas que comprometem a produção; 2) o porte das máquinas, que não atendem aos pequenos e médios produtores (maioria no país); 3) o excessivo peso dos maquinários, que causam compactação do solo; 4) Colheita de apenas duas fileiras (possibilitar a colheita de várias fileiras de cana-de-açúcar para diminuir os custos de operação). Considerando isso, a presente pesquisa é resultado de levantamento em documentos de patentes para prospectar o atual estado tecnológico em sistemas de colheita; focando principalmente o sistema mecanizado de colheita de cana-de-açúcar e, em especial, o subsistema de corte, construindo indicadores tecnológicos que venham contribuir para o avanço do conjunto de soluções agrícolas na realização da colheita mecanizada da cana. A metodologia utilizada nesta dissertação foi o levantamento bibliográfico em documentos de patentes, presentes na base de dados Derwent Innovations Index. Foi desenvolvida uma expressão de busca, utilizando a Classificação Internacional de Patentes CIP; e as palavras-chaves que são limitadores do universo da pesquisa no qual se recuperou 587 registros de patentes considerados relevantes. Após o tratamento desses dados no Infotrans, foram tratados no software VantagePoint que cruzou dados e criou tesauros, possibilitando algumas inferências. Os resultados alcançados permitiram identificar algumas situações que mostram quais são as fronteiras tecnológicas em colheita de cana-de-açúcar. Pode-se identificar, ainda, quais os países e as empresas que mais depositam patentes, além de ter identificado quais países são entrantes na corrida tecnológica para a mecanização da colheita. Um exemplo é a expressiva participação da China, a partir de 2005, em número de pedido de patentes. Com isso, foi possível traçar alguns cenários futuros que são melhor explicitados no terceiro capítulo: referente aos resultados alcançados.

Energy harvesting (EH) nodes, which harvest energy from the environment in order to communicate over a wireless link, promise perpetual operation of wireless networks. The primary focus of the communication system design shifts from being as energy conservative as possible to judiciously handling the randomness in the energy harvesting process in order to enhance the system performance. This engenders a significant redesign of the physical and multiple access layers of communication. In this thesis, we address the problem of maximizing the throughput of a system that consists of rate-adaptive EH nodes that transmit data to a common sink node. We consider the practical case of discrete rate adaptation in which a node selects its transmission power from a set of finitely many rates and adjusts its transmit power to meet a bit error rate (BER) constraint. When there is only one EH node in the network, the problem involves determining the rate and power at which the node should transmit as a function of its channel gain and battery state. For the system with multiple EH nodes, which node should be selected also needs to be determined. We first prove that the energy neutrality constraint, which governs the operation of an EH node, is tighter than the average power constraint. We then propose a simple rate and power adaptation scheme for a system with a single EH node and prove that its throughput approaches the optimal throughput arbitrarily closely. We then arrive at the optimal selection and rate adaptation rules for a multi-EH node system that opportunistically selects at most one node to transmit at any time. The optimal scheme is shown to significantly outperform other ad hoc selection and transmission schemes. The effect of energy overheads, such as battery storage inefficiencies and the energy required for sensing and processing, on the transmission scheme and its overall throughput is also analytically characterized. Further, we show how the time and energy overheads incurred by the opportunistic selection process itself affect the adaptation and selection rules and the overall system throughput. Insights into the scaling behavior of the average system throughput in the asymptotic regime, in which the number of nodes tend to infinity, are also obtained. We also optimize the maximum time allotted for selection, so as to maximize the overall system throughput. For systems with EH nodes or non-EH nodes, which are subject to an average power constraint, the optimal rate and power adaptation depends on a power control parameter, which hitherto has been calculated numerically. We derive novel asymptotically tight bounds and approximations for the same, when the average rate of energy harvesting is large. These new expressions are analytically insightful, computationally useful, and are also quite accurate even in the non-asymptotic regime when average rate of energy harvesting is relatively small. In summary, this work develops several useful insights into the design of selection and transmission schemes for a wireless network with rate-adaptive EH nodes.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The focus of the study is to theoretically assess tank-water demand and employ methods to establish the actual tank-water demand at selected houses in a case study area. This study also examines the influence of domestic rainwater harvesting systems when used in combination with a municipal water distribution system. The case study comprises of 410 low cost housing units in the Western Cape. The system demand patterns of low cost housing units are uncharacteristic, when compared with suburban system demand patterns, and cannot be defined by traditional models. Similarly, the use of rainwater harvesting systems in these areas follows an unconventional routine that is yet to be defined. A stochastic end-use model for water demand is developed which produces temporal profiles for water supplied from both sources, namely the water distribution system and the rainwater harvesting system. The model approximates a daily system and tank-water demand pattern for a single domestic household, using @RISK software. The demand estimation methodology is clarified through application on a particular case study site where harvested rainwater is frequently utilized. Estimates of the parameter values are based on consumer surveys and previous studies on the case study area, where the household size was defined in the form of a probability distribution. The results confirm the atypical system demand patterns in low cost housing units units. Although two clear peaks exist in the morning and in the evening, a relatively constant average flow is present throughout the day. A sensitivity analysis of all the model parameters verified that the household size has the most substantial influence on the tank-water demand pattern. The system and tank-water demand patterns were compared to published average daily water demand guidelines, which confirmed that increased water savings could be achieved when the rainwater source is accessible inside the household with minimal effort. The stochastic demand profiles derived as part of this research agree with the metered system demand in the same area. The results of this study could be incorporated into the future development of national standards. / AFRIKAANSE OPSOMMING: Die fokus van die studie is om die tenkwater-aanvraag teoreties te ontleed en metodes in werking te stel om die werklike tenkwater-aanvraag vas te stel by geselekteerde huise in ‘n gevallestudie area. Hierdie studie ondersoek ook die invloed van plaaslike reënwater-herwinningstelsels wanneer dit gebruik word in kombinasie met ‘n munisipale waterverspreidingstelsel. Die gevallestudie bestaan uit 410 laekoste behuisingseenhede in die Wes-Kaap. Die stelsel-aanvraagpatrone van laekoste behuisingseenhede is verskillend wanneer dit met voorstedelike stelsel-aanvraagpatrone vergelyk word en kan nie gedefinieer word deur tradisionele modelle nie. Soortgelyk volg die gebruik van reënwater-herwinningstelsels in hierdie areas ‘n onkonvensionele roetine. ‘n Stogastiese eindgebruikmodel vir water-aanvraag is ontwikkel, wat tydelike profiele genereer vir water wat van beide bronne verskaf word, naamlik die waterverspreidingstelsel en die reënwater-herwinningstelsel. Die model bepaal by benadering ‘n daaglikse stelsel- en tenkwater-aanvraagpatroon vir ‘n enkele plaaslike huishouding, deur @RISK sagteware. Die aanvraag-beramingstegnieke word verduidelik deur toepassing op ‘n spesifieke gevallestudie, waar herwinde reënwater gereeld gebruik word. Die parameter waardeberamings is gebaseer op verbruikers-opnames en vorige studies oor die gevallestudie-gebied, waar die grootte van die huishoudings bepaal was in die vorm van 'n waarskynlikheidsverspreiding. Die resultate bevestig die atipiese stesel aanvraagpatrone in laekoste behuisingseenhede eenhede. Alhoewel twee duidelike pieke in die oggend en die aand voorkom, is ‘n relatiewe konstante vloei dwarsdeur die dag teenwoordig. ‘n Sensitiwiteitsanalise van al die modelparameters bevestig dat die grootte van die huishouding die grootste beduidende invloed op tenkwater- aanvraagpatrone het. Die stelsel- en tenkwater-aanvraagpatrone was vergelyk met gepubliseerde gemiddelde daaglikse water-aanvraag riglyne wat bevestig dat meer waterbesparings bereik kan word waar die reënwaterbron binne die huishouding beskikbaar is met minimale moeite. Die stogastiese aanvraagprofiele, wat as deel van hierdie navorsing afgelei was, stem saam met die gemeterde stelsel-aanvraagpatroon van dieselfde area. Die resultate van hierdie studie kan in die toekomstige ontwikkeling van nasionale standaarde opgeneem word.