Wireless sensor networks suffer from limited power resources. Therefore, managing the energy constraints and exploring new ways to minimize the power consumption during the operation of the nodes are critical issues. Conventional MAC protocols deal with this problem without considering the internal properties of the sensor nodes’ batteries. However, recent studies about battery modeling and behaviour showed that the pulsed discharge mechanism and the charge recovery effect may have a significant impact on wireless communication in terms of power saving. In this thesis we propose two battery-aware MAC protocols that take benefit of these factors to save more energy and to prolong the lifetime of the nodes/network without affecting the throughput. In both protocols we measure the remaining battery capacity of the node and use that measurement in the back-off scheme. The first protocol gives the nodes with higher remaining battery capacity more priority to access the medium, while the other one provides more medium access priority to the nodes with lower remaining battery capacity. The objective is to investigate, through simulations, which protocol reduces the power consumption of the nodes, improve the lifetime of the network, and compare the results with the CSMA-CA protocol.

Wireless sensor networks suffer from limited power resources. Therefore, managing the energy constraints and exploring new ways to minimize the power consumption during the operation of the nodes are critical issues. Conventional MAC protocols deal with this problem without considering the internal properties of the sensor nodes’ batteries. However, recent studies about battery modeling and behaviour showed that the pulsed discharge mechanism and the charge recovery effect may have a significant impact on wireless communication in terms of power saving. In this thesis we propose two battery-aware MAC protocols that take benefit of these factors to save more energy and to prolong the lifetime of the nodes/network without affecting the throughput. In both protocols we measure the remaining battery capacity of the node and use that measurement in the back-off scheme. The first protocol gives the nodes with higher remaining battery capacity more priority to access the medium, while the other one provides more medium access priority to the nodes with lower remaining battery capacity. The objective is to investigate, through simulations, which protocol reduces the power consumption of the nodes, improve the lifetime of the network, and compare the results with the CSMA-CA protocol.

Wireless sensor networks suffer from limited power resources. Therefore, managing the energy constraints and exploring new ways to minimize the power consumption during the operation of the nodes are critical issues. Conventional MAC protocols deal with this problem without considering the internal properties of the sensor nodes’ batteries. However, recent studies about battery modeling and behaviour showed that the pulsed discharge mechanism and the charge recovery effect may have a significant impact on wireless communication in terms of power saving. In this thesis we propose two battery-aware MAC protocols that take benefit of these factors to save more energy and to prolong the lifetime of the nodes/network without affecting the throughput. In both protocols we measure the remaining battery capacity of the node and use that measurement in the back-off scheme. The first protocol gives the nodes with higher remaining battery capacity more priority to access the medium, while the other one provides more medium access priority to the nodes with lower remaining battery capacity. The objective is to investigate, through simulations, which protocol reduces the power consumption of the nodes, improve the lifetime of the network, and compare the results with the CSMA-CA protocol.

Wireless sensor networks suffer from limited power resources. Therefore, managing the energy constraints and exploring new ways to minimize the power consumption during the operation of the nodes are critical issues. Conventional MAC protocols deal with this problem without considering the internal properties of the sensor nodes’ batteries. However, recent studies about battery modeling and behaviour showed that the pulsed discharge mechanism and the charge recovery effect may have a significant impact on wireless communication in terms of power saving. In this thesis we propose two battery-aware MAC protocols that take benefit of these factors to save more energy and to prolong the lifetime of the nodes/network without affecting the throughput. In both protocols we measure the remaining battery capacity of the node and use that measurement in the back-off scheme. The first protocol gives the nodes with higher remaining battery capacity more priority to access the medium, while the other one provides more medium access priority to the nodes with lower remaining battery capacity. The objective is to investigate, through simulations, which protocol reduces the power consumption of the nodes, improve the lifetime of the network, and compare the results with the CSMA-CA protocol.

Yes / The shape memory effect of highly oriented long‐chain‐branched poly(lactic acid) (LCB‐PLA) prepared through solid‐phase die drawing technology was studied by comparison with PLA. When the recovery temperature increased from 60°C to 120°C, for PLA, only one‐step recovery at about 80°C can be observed and the recovery ratio was below 21.5%, while, for LCB‐PLA, multiple recovery behavior with high recovery ratio of 78.8% can be achieved. For oriented PLA, the recovery curve of the final sample showed the same trend with that of sample suffering just free drawing; while for oriented LCB‐PLA, the recovery curve of the final sample showed the same trend with that of sample suffering just die drawing. After shape recovery, the mechanical properties of LCB‐PLA showed a linear downward trend with the recovery temperature. Together with amorphous phase, the oriented mesomorphic phase, which formed during solid die drawing, can act as switching domains. And thus, upon heating, the chain segment of amorphous phase relaxed at first and triggered the first macroscopical shape recovery, leading to the decrease of long period (Lac) and the thickness of the amorphous layer (La). Then, with further increasing temperature, the oriented mesomorphic phase gradually relaxed resulting subsequently multi‐shape recovery, and the Lac and the La further decreased. Therefore, by regulating the recovery temperature of oriented LCB‐PLA, the shape recovery ratio and mechanical strength can be controlled effectively, and thus the self‐reinforced and self‐fastening effect can be achieved simultaneously for PLA as bone fixation material.

Orientador: Osvair Vidal Trevisan / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Instituto de Geociencias / Made available in DSpace on 2018-08-12T20:49:17Z (GMT). No. of bitstreams: 1 MateoHernandez_JuanAlberto_M.pdf: 12401820 bytes, checksum: 705c41d03544d222731ce816469f47c2 (MD5) Previous issue date: 2006 / Resumo: Neste trabalho são investigados os impactos individual e coletivo dos mecanismos de gás em solução, geração de CO2, destilação, embebição capilar e drenagem gravitacional, sobre a recuperação de óleo e gás, durante a injeção continua de vapor num reservatório naturalmente fraturado contendo óleo pesado. A investigação é feita através de simulação numérica dos fenômenos em modelos padrões de reservatórios. Dois modelos numéricos semelhantes são usados para representar o processo de aquecimento da matriz. O primeiro descreve o aquecimento de uma seção horizontal bidimensional de um bloco da matriz circundado por uma fratura na qual circula vapor. O segundo modelo descreve o aquecimento de um bloco de matriz semelhantemente circundado por uma fratura em que circula vapor, porém na direção vertical, visando agregar o efeito da ação da gravidade. Os estudos foram conduzidos para rochas saturadas com óleo vivo. As propriedades da rocha são as de um reservatório carbonático fraturado real e as propriedades dos fluidos se referem também ao mesmo caso real. Alem disso, as condições operacionais adotadas de pressão e temperatura são as observadas no campo, tornando o estudo e suas conclusões como próprias de um estudo de caso. Os resultados mostram que os principais mecanismos de recuperação de óleo da matriz durante o intervalo de aquecimento de 10 anos, foram os mecanismos de gás em solução e de destilação por arraste de vapor. Este último é o mecanismo de maior importância e é responsável pelo melhoramento da qualidade do óleo produzido / Abstract: In this work, the individual and collective impacts of the mechanisms solution gas drive, CO2 generation, steam distillation, capillary imbibition and drainage gravitational, on the oil and gas recovery, were investigated during the steamflooding of a naturally fractured reservoir containing heavy oil. The investigation was performed for standard reservoir models through numeric simulation. Two similar numerical models represent the matrix heating process. The first describes the heating of a horizontal cross-section of a matrix block surrounded by a fracture, in which the steam is flooding. The second model describes the same method of matrix heating, which was represented in the first model, but in the vertical direction, investigating the action of gravity. The studies were performed for a rock saturated with live oil. The rock properties are the same of a real fractured carbonate reservoir and the fluid properties also refer to the same real case. In addition, the adopted field operational parameters (pressure and temperature) refer to field conditions, turning the study and its conclusions as proper of a case study. The results show that the main mechanisms of oil recovery for the matrix block during the heating interval of 10 years were the integrated action of solution gas and steam distillation. The latter is the dominant mechanism and it is responsible for the improvement in the quality of the produced oil / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo