Energy harvesting and energy storage are two most important technologies in today's green and renewable energy science. As for energy harvesting, the fundamental science and practically applicable technologies are not only essential in realizing the self-powered electronic devices and systems, but also tremendously helpful in meeting the rapid-growing world-wide energy consumptions. Mechanical energy is one of the most universally-existing, diversely-presenting, but usually-wasted energies in the natural environment. Owing to the limitations of the traditional technologies for mechanical energy harvesting, it is highly desirable to develop new technology that can efficiently convert different types of mechanical energy into electricity. On the other hand, the electricity generated from environmental energy often needs to be stored before used to drive electronic devices. For the energy storage units such as Li-ion batteries as the power sources, the limited lifetime is the prominent problem. Hybridizing energy harvesting devices with energy storage units could not only provide new solution for this, but also lead to the realization of sustainable power sources. In this dissertation, the research efforts have led to several critical advances in a new technology for mechanical energy harvesting—triboelectric nanogenerators (TENGs). Previous to the research of this dissertation, the TENG only has one basic mode—the contact mode. Through rational structural design, we largely improved the output performance of the contact-mode TENG and systematically studied their characteristics as a power source. Beyond this, we have also established the second basic mode for TENG—the lateral sliding mode, and demonstrated sliding-based disk TENGs for harvesting rotational energy and wind-cup-based TENGs for harvesting wind energy. In order to expand the application and versatility of TENG by avoid the connection of the electrode on the moving part, we further developed another basic mode—freestanding-layer mode, which is capable of working with supreme stability in non-contact mode and harvesting energy from any free-moving object. Both the grating structured and disk-structured TENGs based on this mode also display much improved long-term stability and very high energy conversion efficiency. For the further improvement of the TENG’s output performance from the material aspect, we introduced the ion-injection method to study the maximum surface charge density of the TENG, and for the first time unraveled its dependence on the structural parameter—the thickness of the dielectric film. The above researches have largely propelled the development of TENGs for mechanical energy harvesting and brought a big potential of impacting people’s everyday life. Targeted at developing sustainable and independent power sources for electronic devices, efforts have been made in this dissertation to develop new fundamental science and new devices that hybridize the nanogenerator-based mechanical energy harvesting and the Li-ion-battery-based energy storage process into a single-step process or in a single device. Through hybridizing a piezoelectric nanogenerator with a Li-ion battery, a self-charging power cell has been demonstrated based on a fundamentally-new mechanical-to-electrochemcial process. The triboelectric nanogenerator as a powerful technology for mechanical energy harvesting has also been hybridized with a Li-ion battery into a self-charging power unit. This new concept of device can sustainably provide a constant voltage for the non-stop operation of electronic devices.

Submitted by Livia Mello (liviacmello@yahoo.com.br) on 2016-10-11T13:53:16Z No. of bitstreams: 1 DissRPS.pdf: 5427794 bytes, checksum: c1626fcdcaf2b48b6a76b63021220431 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-21T12:12:21Z (GMT) No. of bitstreams: 1 DissRPS.pdf: 5427794 bytes, checksum: c1626fcdcaf2b48b6a76b63021220431 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-21T12:12:28Z (GMT) No. of bitstreams: 1 DissRPS.pdf: 5427794 bytes, checksum: c1626fcdcaf2b48b6a76b63021220431 (MD5) / Made available in DSpace on 2016-10-21T12:12:34Z (GMT). No. of bitstreams: 1 DissRPS.pdf: 5427794 bytes, checksum: c1626fcdcaf2b48b6a76b63021220431 (MD5) Previous issue date: 2016-08-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This study aims to propose a didactic sequence involving the use of resources and diversified activities applied to the teaching of Conservation of Mechanical Energy and its applications. The didactic sequence was based on the Theory of Meaningful Learning and the idea of concept maps, taking into consideration the principles and present steps in Potentially Meaningful Teaching Units (PMTU). In the didactic sequence of concepts approach is through reading popular science short texts involving different contexts and applications, through an animation and a computer simulation, using questionnaires, including a mathematical formalization, and the use of conceptual maps. The elaborate didactic sequence was implemented in a class of 1 st year of high school, in a private school in the city of Ribeirão Preto, SP. In general, the application of the teaching sequence obtained good results. In addition to satisfactory learning outcomes, it was noticed the involvement of students in the proposed activities, showing satisfied with the dynamics of classes, and even explaining that they facilitated the understanding of the study content, especially those involving conceptual and computing resources maps. From the results, it is understood that the educational product developed, a didactic sequence guided by the idea of PMTU, has a potential in terms of promoting the learning of mechanical energy conservation concepts can be implemented in other contexts. / Este trabalho tem por finalidade propor uma sequência didática envolvendo o uso de recursos e atividades diversificadas aplicadas ao ensino da Conservação da Energia Mecânica e suas aplicações. A sequência didática foi norteada pela Teoria da Aprendizagem Significativa e pela ideia de Mapas Conceituais, considerando ainda os princípios e passos presentes nas Unidades de Ensino Potencialmente Significativa (UEPS). Na sequência didática, a abordagem dos conceitos se dá através da leitura de textos curtos de divulgação científica envolvendo diferentes contextos e aplicações, através de uma animação e de uma simulação computacional, com o uso de questionários, incluindo uma formalização matemática, além do uso de mapas conceituais. A sequência didática elaborada foi implementada em uma turma de 1o ano do Ensino Médio, em uma escola privada na cidade de Ribeirão Preto, SP. De um modo geral, a aplicação da Sequência Didática obteve bons resultados. Além de resultados satisfatórios de aprendizagem, foi perceptível o envolvimento dos alunos nas atividades propostas, mostrando-se satisfeitos com a dinâmica das aulas e inclusive explicitando que estas facilitaram o entendimento do conteúdo estudado, especialmente as que envolviam mapas conceituais e recursos computacionais. A partir dos resultados obtidos, compreende-se que o produto educacional elaborado, uma sequência didática orientada pela ideia de UEPS, possui um potencial em termos de promoção da aprendizagem dos conceitos de conservação de energia mecânica, podendo ser implementada em outros contextos.

<p>In aeromechanical design one of the major rules is to operate under High Cyclic Fatigue (HCF) margins and away from flutter. The level of dynamic excitations and risk of HCF can be estimated by performing forced response analyses from blade row interaction forces or Low Engine Order (LEO) excitation mechanisms. On the other hand, flutter stability prediction can be assessed by calculation of aerodynamic damping forces due to blade motion. In order to include these analyses as regular practices in an industrial aeromechanical design process, interaction between the fields of fluid and structural dynamics must be established in a rather simple yet accurate manner. Effects such as aerodynamic and structural mistuning should also be taken into account where parametric and probabilistic studies take an important role.</p><p>The present work presents the development and validation of a numerical tool for aeromechanical design. The tool aims to integrate in a standard and simple manner regular aeromechanical analysis such as forced response analysis and aerodynamic damping analysis of bladed disks.</p><p>Mistuning influence on forced response and aerodynamic damping is assessed by implementing existing model order reduction techniques in order to decrease the computational effort and assess results in an industrially applicable time frame.  The synthesis program solves the interaction of structure and fluid from existing Finite Element Modeling (FEM) and Computational Fluid Dynamics (CFD) solvers inputs by including a mapping program which establishes the fluid and structure mesh compatibility. Blade row interaction harmonic forces and/or blade motion aerodynamic damping forces are inputs from unsteady fluid dynamic solvers whereas the geometry, mass and stiffness matrices of a blade alone or bladed disk sector are inputs from finite element solvers. Structural and aerodynamic damping is also considered.</p><p>Structural mistuning is assessed by importing different sectors and any combinations of the full disk model can be achieved by using Reduced Order Model (ROM) techniques. Aerodynamic mistuning data can also be imported and its effects on the forced response and stability assessed. The tool is developed in such a way to allow iterative analysis in a simple manner, being possible to realize aerodynamically and structurally coupled analyses of industrial bladed disks. A new method for performing aerodynamic coupled forced response and stability analyses considering the interaction of different mode families has also been implemented. The method is based on the determination of the aerodynamic matrices by means of least square approximations and is here referred as the Multimode Least Square (MLS) method.</p><p>The present work includes the program description and its applicability is assessed on a high pressure ratio transonic compressor blade and on a simple blisk.</p> / Turbopower / AROMA

Hotels constitute one of the main, and still expanding, pillars of the tourism sector and are highly unique among other commercial buildings. Resource intensive and frequently inefficient systems and operational routines applied in the sector, result in considerable environmental impact and indicate an urgent need for more environmentally sound practices and products in the hotel industry. A certain level of activity in the area of reducing resource use has been observed for quite some time but the motivation for this was related to cost-benefit issues rather than the environment. Furthermore, most of the initiatives are still considered to be best practice case studies and not daily routines. The constantly increasing prices of basic commodities, such as energy resources and water, encourage the implementation of energy and water efficiency and conservation measures in hotel facilities. To this end, numerous guidelines and initiatives have been produced by hotel-related organisations. The study of attitudes among 610 European hoteliers indicated that, at the moment, the level of environmental awareness among hotel managers is not high enough to introduce significant changes, although attitudes differ depending on the country of origin and the corporate policy. The prospects of significant cost savings, as well as customer demand were identified as the most likely parameters to enhance environmental responsibility among hoteliers. The popularity of CSR reporting and sustainability indices, especially among the larger companies, leads the author to believe that the industry is preparing to change. Many of the companies running hotels are also reporting their environmental management goals and indicators of environmental performance, while benchmarking and all types of comparison league tables are gaining popularity. There is, however, no system or methodology of data collection and monitoring that is universally accepted or applicable throughout the hotel sector. Furthermore, the accuracy and validity of the published performance indicators and benchmarks is widely debated due to large variations in the figures reported. The analyses performed on data from over 180 upscale and mid-market European chain hotels (Hilton International and Scandic) indicated that even among relatively uniform (service-wise) hotels the amenities offered did influence consumption, further complicating the concept and applicability of uniform benchmarking and resource consumption modelling. It was thus concluded that, creating a uniform model for all hotels is almost impossible, or would require a significant amount of very detailed input data, and that the results could still be highly inaccurate. Instead, it was suggested that it might actually be more accurate to develop models for individual hotels. Such an approach would allow for the modelling of the behaviour of all types of hotels with no size, type of services or standard limitations. Multi-variate step-wise regression analyses performed on individual Scandic hotels in Sweden indicated that energy consumption was dependent on the outdoor air temperature/actual heating degree days, while water consumption was mainly influenced by the number of guest-nights sold. Experience gained by the author during the process of the Hilton Environmental Reporting system upgrade allowed for the formulation of a set of rules of thumb that ought to be followed in the design of similar schemes. The experience of various regions and numerous companies also suggests that well designed and implemented environmental and resource management programs bring significant benefits at an individual as well as a corporate level. This study provides an indication of the strategies that can be used by various stakeholders in the process of development and implementation of such programs. This research further suggests that future developments in environmental performance indicators and benchmarking may best be served by disaggregating hotels into modules (such as guest-rooms, catering outlets, conference centres) and developing consumption models and best practice indicators for these particular components. The individual efficiencies/performance indicators should then be combined and weighted to provide a just overall evaluation of a facility that could then be compared to a benchmark (developed in the same manner). In a similar manner, sustainability assessment schemes and indicators for destinations and communities could be developed. However, more accurate and differentiated knowledge of the individual performance of sub-systems is necessary to proceed with such an alternative. In addition, the methodologies for data collection and reporting procedures, at all levels of the company and sector, need to be standardized and detailed / QC 20100818

For the application of minichannel heat exchangers, it is necessary to have accurate design tools for predicting heat transfer and pressure drop. Until recently, this type of heat exchangers was not well studied, and in the scientific literature there were large discrepancies between results reported by different investigators. The present thesis aims to add to the knowledge of the fundamentals of single- and two-phase flow heat transfer and pressure drop in narrow channels, thereby aiding in the development of this new, interesting technology with the possibility of decreasing the size of electronics through better cooling, and of increasing the energy efficiency of thermal processes and thermodynamic cycles through enhanced heat transfer. A comprehensive experimental single-phase flow and saturated flow boiling heat transfer and pressure drop study has been carried out on vertical stainless steel tubes with inner diameters of 1.700, 1.224 and 0.826 mm, using R-134a as the test fluid. The heat transfer and pressure drop results were compared both to conventional correlations developed for larger diameter channels and to correlations developed specifically for microscale geometries. Contrary to many previous investigations, this study has shown that the test data agree well with single-phase heat transfer and friction factor correlations known to be accurate for larger channels, thus expanding their ranges to cover mini/microchannel geometries. The main part of the study concerns saturated flow boiling heat transfer and pressure drop. Tests with the same stainless steel tubes showed that the heat transfer is strongly dependent on heat flux, but only weakly dependent on mass flux and vapor fraction (up to the location of dryout). This behavior is usually taken to indicate a dominant influence of nucleate boiling, and indicates that the boiling mechanism is strongly related to that in nucleate boiling. The test data for boiling heat transfer was compared to several correlations from the literature, both for macro- and mini-channels. A new correlation for saturated flow boiling heat transfer of refrigerant R-134a correlation was obtained based on the present experimental data. This correlation predicts the presented data with a mean absolute deviation of 8%. The frictional pressure drop results were compared to both macro- and mini channel correlations available from the literature. The correlation suggested by Qu and Mudawar (2003) gave the best prediction to the frictional two-phase pressure drop within the studied ranges. A unique visualization study of saturated flow boiling characteristics in a vertical 1.332 mm inner diameter quartz tube, coated with a transparent heater has also been conducted. The complete evaporation process in a heated circular mini-channel has been studied visually in detail using high speed CCD camera. The study revealed the developments of the flow patterns and the behavior from bubble nucleation to the dry out of the liquid film. The bubble departure frequency, diameter, growth rate, and velocity were determined by analyzing the images. Finally, a flow pattern map for boiling flow in microchannels has been developed based on the test data. / QC 20100812

This thesis theoretically and experimentally investigates different aspects of the application of CO2 in supermarket refrigeration. Theoretical analysis has been performed using computer simulation models developed to simulate CO2 indirect, NH3/CO2 cascade, CO2 trans-critical and direct expansion (DX) R404A systems. The models supported the selection of the CO2 system solutions to be tested experimentally and facilitated the design of NH3/CO2 cascade and trans-critical systems test rigs. Performance evaluation and systems’ optimizations have also been carried out. In order to verify the findings of the theoretical analysis an experimental evaluation has been performed whereby a scaled-down medium size supermarket has been built in a laboratory environment. NH3/CO2 cascade and trans-critical systems have been tested and compared to a conventional R404A system installed in the same laboratory environment. Experimental findings have been compared to the computer simulation models. In supermarket refrigeration applications, safety is a major concern because of the large number of people that might be affected in the event of leakage. Therefore, a computer simulation model has been developed to perform calculations of the resulting concentration levels arising from different scenarios for leakage accidents in the supermarket. The model has been used to validate some of the risks associated with using CO2 in the application of supermarket refrigeration. Results of the experiments and the computer simulation models showed good agreement and suggest that the NH3/CO2 cascade system is a more efficient solution than the analyzed conventional ones for supermarket refrigeration. On the other hand, CO2 trans-critical solutions have efficiencies comparable to the conventional systems analyzed, with potential for improvements in the trans-critical systems. From a safety point of view, the analysis of the calculations’ results clearly shows that using CO2 in supermarket refrigeration does not create exceptional health risks for customers and workers in the shopping area. Studies conducted in this thesis prove that the CO2 systems investigated are efficient solutions for supermarket refrigeration. / QC 20100909

<p>ABSTRACT</p><p>Cities throughout Asia have experienced unprecedented economic development over the past decades. In many cases this has contributed to their rapid and uncontrolled growth, which has resulted in a multiplicity of problems, including rapid population increase, enhanced environmental pollution, collapsing traffic systems, dysfunctional waste management, and rapid increases in the consumption of energy, water and other resources. The significant energy use in cities is not very well perceived in Asian countries. Although a number of studies into energy consumption across various sectors have been conducted, most are from the national point of view. Energy demand analysis is not considered important at the level of the city. The thesis is focused on the dynamics of energy utilization in Asian mega-cities, and ultimately aims at providing strategies for maximizing the use of renewable energy in large urban systems.</p><p>The study aims at providing an in-depth understanding of the complex dynamics of energy utilization in urban mega-centers. An initial general analysis is complemented by a detailed study of the current situation and future outlook for the city of Bangkok, Thailand. An integrated approach applied to the study includes identification of the parameters that affect the utilization of energy in mega-cities and a detailed analysis of energy flows and their various subsystems, including commercial, industrial, residential and that of transportation. The study investigates and evaluates the energy models most commonly used for analyzing and simulating energy utilization. Its purpose is to provide a user-friendly tool suitable for decision-makers in developing an energy model for large cities. In addition, a Multi-Criteria Decision-Making (MCDM) process has been developed to assess whether or not the energy systems meet the sustainability criteria.</p><p>A metabolic approach has been employed to analyze the energy flow and utilization in selected Asian mega-cities, including Bangkok, Beijing, Shanghai, and Tokyo. The approach is applied to measure the majority of indirect energy flows or the energy embodied in the flows of goods and services involving the residents of those cities. Since the function of cities is to serve the lives of the residents, indirect energy consumption could be regarded as being of equal importance as that of direct energy use. The essence of embodied energy is that an indirect reflection upon behavior following direct energy consumption. It can illustrate how a city relies on the outside, for example other cities, countries, etc. and provides some interesting information that cannot be easily drawn from the direct energy demand. The study reveals that the indirect energy demand is more significant than the direct energy demand in Bangkok, Shanghai, and Tokyo, while direct energy demand is greater than the indirect energy demand in Beijing. This can be explained by the fact that Bangkok, Shanghai, and Tokyo have a greater reliance upon the outside in terms of energy demand.</p><p>The Long-range Energy Alternative Planning (LEAP) system has been selected to perform Bangkok energy modeling. In a Bangkok case study a range of policy interventions are selected and how these would change the energy development in Bangkok by the year 2025 is examined. Different policies can be grouped by the sectors analyzed. The only supply-side policy considered meets an existing target of having 10% of electricity generated from renewable sources. The study period for the model started in 2005 and ends in 2025, with the year 2000 taken as the base year. The proposed scenarios were evaluated using the MCDM approach to rate their sustainability. Team members found that this method provided a methodology to help decision-makers to systematically identify management objectives and priorities.</p>

Made available in DSpace on 2018-06-27T19:13:33Z (GMT). No. of bitstreams: 3 Vinicius Bisognin.pdf: 3237197 bytes, checksum: d5213702c8f66050cb6fb6af982a3d09 (MD5) Vinicius Bisognin.pdf.txt: 117183 bytes, checksum: 408acfe12278db4be967a0514d2f4607 (MD5) Vinicius Bisognin.pdf.jpg: 3397 bytes, checksum: e96b2dd1373c87f056e7bc7925ef4a54 (MD5) Previous issue date: 2014-04-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Computational resources have been identified as important auxiliary teaching, in view of the current technological developments. Thus, the purpose of this study demand through the use of computational simulations and animations to provide high school students an understanding of the more general principle of Conservation of Mechanical Energy. Learning activities with the use of computational simulations and animations are structured according to the methodology of Three Pedagogical Moments (TMP) and will make use of a Blog as a Virtual Learning Environment (VLE) to provide greater interaction between students and teacher and between them and the simulations and animations. It is expected that the learning of physics concepts involved in the subject of Mechanical Energy Conservation is enhanced. / Os recursos computacionais têm sido apontados como importantes auxiliares do ensino, tendo em vista a evolução tecnológica atual. Desta forma, a proposta desse trabalho procura através da utilização de simulações e animações computacionais proporcionar aos estudantes de Ensino Médio uma compreensão mais generalizada do princípio da Conservação de Energia Mecânica. As atividades de aprendizagem com o uso das simulações e animações computacionais estão estruturadas de acordo com a metodologia dos Três Momentos Pedagógicos (TMP) e farão uso de um Blog como Ambiente Virtual de Aprendizagem (AVA) para proporcionar maior interação entre os estudantes e o professor e entre eles e as simulações e animações. Espera-se que a aprendizagem dos conceitos físicos envolvidos no tema Conservação de Energia Mecânica seja potencializada.

Les problématiques scientifiques étudiant la biomécanique du mouvement de pédalage en cyclisme ont fait et font toujours l'objet de nombreux travaux. Ces travaux touchent de divers domaines, technologique par exemple pour l'amélioration du matériel qui a considérablement évolué, physiologique pour l'amélioration des capacités physiques et des rendements énergétiques en fonction des styles de pédalage, et biomécanique pour l'expertise, en particulier, de l'efficacité de mouvement de pédalage. Le travail présenté s'inscrit dans ce dernier champ scientifique : la biomécanique du mouvement.</br>Le travail réalisé a bénéficié d'un appel à projet de l'Agence Française de la Lutte contre le Dopage avec pour objectif : « [SIC] se réarmer vis-à-vis du dopage en adoptant des démarches qui se veulent originales et concrètes, notamment en se plaçant du point de vue de l'entourage scientifique de sportifs dopés » en se focalisant sur les thèmes « [SIC] Travail, puissance et rendement énergétique».</br>Dans ce contexte, l'objectif général des travaux est l'évaluation du profil biomécanique du coureur cycliste par mesures en laboratoire. Pour cela, une plateforme expérimentale a été validée et nous a permis d'aborder deux questions centrales i) qu'est ce qui crée la force produite à la pédale ? ii) que peut-on attendre d'une évaluation énergétique mécanique du mouvement de pédalage? Ces deux points sont abordés à partir d'un protocole de tests de type incrémentiel tel que l'exige la Fédération Française de Cyclisme. Les résultats ont été obtenus sur une cohorte de coureurs Elite. / Numerous studies investigated and still investigate pedaling motion in cycling from a biomechanical point of view. These studies involve various fields, like technologic for improving the material which has considerably evolved, physiologic for physical capacities and energy efficiencies' improvement according to pedaling styles, and biomechanics for motion's expertise and pedaling efficiency in particularly. This work takes part in the last scientific field: the biomechanics of movement.</br>This work received a call for proposals of the AFLD (Agence Française de la Lutte contre le Dopage) in order to: "[SIC] rearm regarding doping by adopting original and practical approaches, considering scientific environment of doped athletes" by focusing on the themes of "[SIC] Work, power and energy efficiency".</br>In this context, the general objective of this work is the biomechanical evaluation of cyclist's profile in laboratory conditions. For this, an experimental platform has been validated and allowed us to follow two central issues i) How is created the force produced to the pedal? ii) What can be expected from a mechanical energy evaluation of pedaling motion? These two points are discussed through incremental protocol tests as required by the French Cycling Federation. The results were obtained on a cohort of Elite cyclists.

The development of new types of offshore wind turbine on floating platforms requires the development of new approaches to modelling the combined platform-turbine system. In this thesis a linearised frequency-domain approach is developed which gives fast but approximate results: linearised models of the structural dynamics, hydrodynamics, aerodynamics and control system dynamics are brought together to find the overall response of the floating wind turbine to harmonic wind and wave loading. Initially, a nonlinear flexible multibody dynamics code is developed and verified, which is then used to provide reference nonlinear simulation results. The structural dynamics of a wind turbine on a moving platform are shown to be nonlinear, but for realistic conditions the effects are small. An approximate analysis of the second-order response of floating cylinders to hydrodynamic loads suggests slow drift motion may be relatively small for floating wind turbines, compared to other floating offshore structures. The aerodynamic loads are linearised using both harmonic and tangent linearisation approaches; the harmonic linearisation gives improved results when stall occurs. The wake dynamics can also be included. The control system behaviour is linearised using the same method, which works well when the wind speed is far from the rated wind speed; close to the rated wind speed the nonlinearity is stronger, but further improvement should be possible. These sub-models are combined to give a simple but complete model of a floating wind turbine, with flexible blades and a flexible tower, but neglecting the control system behaviour, wake dynamics and nonlinear hydrodynamic loads. For the OC3-Hywind turbine, the accuracy of the results is assessed by comparison to nonlinear time-domain simulations using the commercial code Bladed. Peak-peak errors of less than 5 % are achievable for many harmonic wind and wave inputs, but certain conditions lead to larger errors. The effect of including linearised control system behaviour is demonstrated for a subset of conditions. Overall, the results are promising but more work is needed for practical application.