Temperature is one of the parameters that limits the output torque and reduces the lifespan of electrical machines. Models that can provide accurate estimation of the temperature field in the most critical components (e.g. windings) at lower computational effort can be useful to improve the design process and reduce the time to market. Depending on the application, engineers usually rely on hi-fidelity models, e.g. based on the finite elements method (FEM), or lower order models, e.g. thermal equivalent circuits (TECs). The aim of the present work is to provide new tools and methodologies to obtain the temperature distribution within the windings using reduced order hi-fidelity models or improved TEC that could account for any working condition, including AC effects. A new methodology, based on the multiple scales method (MSM), is introduced which homogenises the complex windings domain and allows for the estimation of its effective thermal properties. The homogenisation through the MSM is performed solving a single elementary cell. The MSM also allows for the reconstruction of the actual thermal field. Extensive numerical and experimental validation is provided, in particular for the case of electrical windings encapsulated with epoxy. The thermal homogenisation is then combined with an electromagnetic homogenisation technique to estimate winding losses including AC effects, such as proximity and skin effects. The coupled analysis is validated numerically on reference test problems, and experimentally, on a suitably built "motorette". The method is proven to correctly predict losses including thermal effects and to estimate magnitude and location of the temperature hotspot within the winding domain. This work also introduces a new approach for building thermal equivalent circuits that represents the most commonly employed modelling technique for electrical machine thermal analysis. Here the TEC approaches are thoroughly analysed, highlighting limitations. The proposed new technique extends the range of numerical accuracy, accounting for high Biot numbers (up to Bi = 2) and internal heat generation. The result of this approach is higher spatial resolution about the temperature field within the winding domain and thus enables improved information on hotspot location and magnitude. The method is experimentally validated and also applied to model an electrical machine for full-electric in-wheel vehicle propulsion.

A condição do hábitat local em riachos é determinada por fatores naturais e antrópicos, em escala regional e separar a influência relativa desses fatores é difícil, pois geralmente a sua distribuição espacial encontra-se sobreposta. Neste sentido, este estudo tem por objetivo determinar a influência relativa das características naturais e de usos do solo, em escala regional, sobre a condição do hábitat, em escala de trecho de riacho, na bacia hidrográfica do Arroio Candiota, sul do Rio Grande do Sul. Para isso, as características naturais (de relevo e de rede de drenagem) e as atividades antrópicas (usos do solo) foram avaliadas em 26 sub-bacias. Em escala de trecho de riacho, os atributos avaliados foram agrupados em condição do hábitat físico no canal fluvial, qualidade da zona ripária e qualidade da água. Por meio de análise de redundância parcial, determinou-se a percentagem da variação, na condição de cada grupo atributos do hábitat, explicada pelos fatores naturais, pelos fatores antrópicos e pelo seu efeito compartilhado. As sub-bacias maiores tendem a apresentar maior textura no relevo, formato menos circular e menor declive. As sub-bacias com relevo mais acidentado tendem a apresentar maior densidade de drenagem. A vegetação natural ocupa a maior parte da bacia, principalmente as regiões de relevo mais acidentado, porém atividades como agricultura, pecuária, silvicultura e mineração de carvão estão distribuídas pela bacia, principalmente em áreas de relevo mais suave e próximo aos riachos. A maior parte dos riachos apresenta boa qualidade do hábitat, porém em riachos com baixa qualidade observa-se gado na zona ripária ou grande aporte de rejeitos da mineração de carvão. As principais alterações do hábitat físico no canal são assoreamento, dragagem e represamento. Em relação à qualidade da água, pH e condutividade apresentam valores extremos nos riachos associados à mineração de carvão. A condição do hábitat físico no canal é mais influenciada pelas características naturais das sub-bacias, enquanto a qualidade da água está mais associada aos usos do solo. A qualidade da zona ripária, por sua vez, é determinada pelo efeito compartilhado dos fatores naturais e antrópicos. Dessa forma, as atividades antrópicas na bacia hidrográfica exercem maior efeito sobre os atributos mais dinâmicos do hábitat, tendo influência menor sobre processos mais lentos, como alteração no hábitat físico do canal. / The stream local habitat condition is determined by natural and anthropogenic regional characteristics and to determine the relative influence of these factors is difficult because their spatial distribution is usually superimposed. Thus, this study aims to determine the relative influence of natural characteristics and land use, in regional scale, on the the stream local habitat condition in the Arroio Candiota watershed. For this, natural characteristics (relief and drainage network) and human activities (land uses) were evaluated in 26 sub-catchments. In the reach scale, the stream habitat attributes were grouped into stream physical habitat, riparian zone quality and water quality. Using partial redundancy analysis, the percentage of variation in the condition of each group of habitat attributes, explained by natural factors, by human factors and by their shared effect was determined. The major catchments tend to have higher texture in relief, less circular shape and lower slope while catchments with steeper relief tend to have higher drainage density. Most of the Arroio Candiota watershed are occupied by natural vegetation, especially the regions of steeper relief. Agriculture, livestock, forestry and mining are distributed throughout the basin, especially in areas of gentle relief and close to streams. Most streams has good habitat quality, but in streams where quality is low there is livestock in the riparian zone or large supply of wastes from coal mining. The main changes in the physical habitat channel are siltation, dredging and damming. Regarding water quality, pH and conductivity have extreme values in streams associated with coal mining. The condition of physical habitat in the channel is more influenced by the natural characteristics of the catchments, while water quality is more associated with land use. The quality of the riparian zone, in turn, is determined by the shared effect of natural and anthropogenic factors. Thus , the anthropogenic activities in the watershed exert greater effect on the more dynamic attributes of habitat, having less influence on slower processes, such as changes in physical habitat of the channel.

A condição do hábitat local em riachos é determinada por fatores naturais e antrópicos, em escala regional e separar a influência relativa desses fatores é difícil, pois geralmente a sua distribuição espacial encontra-se sobreposta. Neste sentido, este estudo tem por objetivo determinar a influência relativa das características naturais e de usos do solo, em escala regional, sobre a condição do hábitat, em escala de trecho de riacho, na bacia hidrográfica do Arroio Candiota, sul do Rio Grande do Sul. Para isso, as características naturais (de relevo e de rede de drenagem) e as atividades antrópicas (usos do solo) foram avaliadas em 26 sub-bacias. Em escala de trecho de riacho, os atributos avaliados foram agrupados em condição do hábitat físico no canal fluvial, qualidade da zona ripária e qualidade da água. Por meio de análise de redundância parcial, determinou-se a percentagem da variação, na condição de cada grupo atributos do hábitat, explicada pelos fatores naturais, pelos fatores antrópicos e pelo seu efeito compartilhado. As sub-bacias maiores tendem a apresentar maior textura no relevo, formato menos circular e menor declive. As sub-bacias com relevo mais acidentado tendem a apresentar maior densidade de drenagem. A vegetação natural ocupa a maior parte da bacia, principalmente as regiões de relevo mais acidentado, porém atividades como agricultura, pecuária, silvicultura e mineração de carvão estão distribuídas pela bacia, principalmente em áreas de relevo mais suave e próximo aos riachos. A maior parte dos riachos apresenta boa qualidade do hábitat, porém em riachos com baixa qualidade observa-se gado na zona ripária ou grande aporte de rejeitos da mineração de carvão. As principais alterações do hábitat físico no canal são assoreamento, dragagem e represamento. Em relação à qualidade da água, pH e condutividade apresentam valores extremos nos riachos associados à mineração de carvão. A condição do hábitat físico no canal é mais influenciada pelas características naturais das sub-bacias, enquanto a qualidade da água está mais associada aos usos do solo. A qualidade da zona ripária, por sua vez, é determinada pelo efeito compartilhado dos fatores naturais e antrópicos. Dessa forma, as atividades antrópicas na bacia hidrográfica exercem maior efeito sobre os atributos mais dinâmicos do hábitat, tendo influência menor sobre processos mais lentos, como alteração no hábitat físico do canal. / The stream local habitat condition is determined by natural and anthropogenic regional characteristics and to determine the relative influence of these factors is difficult because their spatial distribution is usually superimposed. Thus, this study aims to determine the relative influence of natural characteristics and land use, in regional scale, on the the stream local habitat condition in the Arroio Candiota watershed. For this, natural characteristics (relief and drainage network) and human activities (land uses) were evaluated in 26 sub-catchments. In the reach scale, the stream habitat attributes were grouped into stream physical habitat, riparian zone quality and water quality. Using partial redundancy analysis, the percentage of variation in the condition of each group of habitat attributes, explained by natural factors, by human factors and by their shared effect was determined. The major catchments tend to have higher texture in relief, less circular shape and lower slope while catchments with steeper relief tend to have higher drainage density. Most of the Arroio Candiota watershed are occupied by natural vegetation, especially the regions of steeper relief. Agriculture, livestock, forestry and mining are distributed throughout the basin, especially in areas of gentle relief and close to streams. Most streams has good habitat quality, but in streams where quality is low there is livestock in the riparian zone or large supply of wastes from coal mining. The main changes in the physical habitat channel are siltation, dredging and damming. Regarding water quality, pH and conductivity have extreme values in streams associated with coal mining. The condition of physical habitat in the channel is more influenced by the natural characteristics of the catchments, while water quality is more associated with land use. The quality of the riparian zone, in turn, is determined by the shared effect of natural and anthropogenic factors. Thus , the anthropogenic activities in the watershed exert greater effect on the more dynamic attributes of habitat, having less influence on slower processes, such as changes in physical habitat of the channel.

A condição do hábitat local em riachos é determinada por fatores naturais e antrópicos, em escala regional e separar a influência relativa desses fatores é difícil, pois geralmente a sua distribuição espacial encontra-se sobreposta. Neste sentido, este estudo tem por objetivo determinar a influência relativa das características naturais e de usos do solo, em escala regional, sobre a condição do hábitat, em escala de trecho de riacho, na bacia hidrográfica do Arroio Candiota, sul do Rio Grande do Sul. Para isso, as características naturais (de relevo e de rede de drenagem) e as atividades antrópicas (usos do solo) foram avaliadas em 26 sub-bacias. Em escala de trecho de riacho, os atributos avaliados foram agrupados em condição do hábitat físico no canal fluvial, qualidade da zona ripária e qualidade da água. Por meio de análise de redundância parcial, determinou-se a percentagem da variação, na condição de cada grupo atributos do hábitat, explicada pelos fatores naturais, pelos fatores antrópicos e pelo seu efeito compartilhado. As sub-bacias maiores tendem a apresentar maior textura no relevo, formato menos circular e menor declive. As sub-bacias com relevo mais acidentado tendem a apresentar maior densidade de drenagem. A vegetação natural ocupa a maior parte da bacia, principalmente as regiões de relevo mais acidentado, porém atividades como agricultura, pecuária, silvicultura e mineração de carvão estão distribuídas pela bacia, principalmente em áreas de relevo mais suave e próximo aos riachos. A maior parte dos riachos apresenta boa qualidade do hábitat, porém em riachos com baixa qualidade observa-se gado na zona ripária ou grande aporte de rejeitos da mineração de carvão. As principais alterações do hábitat físico no canal são assoreamento, dragagem e represamento. Em relação à qualidade da água, pH e condutividade apresentam valores extremos nos riachos associados à mineração de carvão. A condição do hábitat físico no canal é mais influenciada pelas características naturais das sub-bacias, enquanto a qualidade da água está mais associada aos usos do solo. A qualidade da zona ripária, por sua vez, é determinada pelo efeito compartilhado dos fatores naturais e antrópicos. Dessa forma, as atividades antrópicas na bacia hidrográfica exercem maior efeito sobre os atributos mais dinâmicos do hábitat, tendo influência menor sobre processos mais lentos, como alteração no hábitat físico do canal. / The stream local habitat condition is determined by natural and anthropogenic regional characteristics and to determine the relative influence of these factors is difficult because their spatial distribution is usually superimposed. Thus, this study aims to determine the relative influence of natural characteristics and land use, in regional scale, on the the stream local habitat condition in the Arroio Candiota watershed. For this, natural characteristics (relief and drainage network) and human activities (land uses) were evaluated in 26 sub-catchments. In the reach scale, the stream habitat attributes were grouped into stream physical habitat, riparian zone quality and water quality. Using partial redundancy analysis, the percentage of variation in the condition of each group of habitat attributes, explained by natural factors, by human factors and by their shared effect was determined. The major catchments tend to have higher texture in relief, less circular shape and lower slope while catchments with steeper relief tend to have higher drainage density. Most of the Arroio Candiota watershed are occupied by natural vegetation, especially the regions of steeper relief. Agriculture, livestock, forestry and mining are distributed throughout the basin, especially in areas of gentle relief and close to streams. Most streams has good habitat quality, but in streams where quality is low there is livestock in the riparian zone or large supply of wastes from coal mining. The main changes in the physical habitat channel are siltation, dredging and damming. Regarding water quality, pH and conductivity have extreme values in streams associated with coal mining. The condition of physical habitat in the channel is more influenced by the natural characteristics of the catchments, while water quality is more associated with land use. The quality of the riparian zone, in turn, is determined by the shared effect of natural and anthropogenic factors. Thus , the anthropogenic activities in the watershed exert greater effect on the more dynamic attributes of habitat, having less influence on slower processes, such as changes in physical habitat of the channel.

A bifurcation analysis is used to investigate the complex dynamics of two heavily loaded single-machine-infinite-busbar power systems modeling the characteristics of the BOARDMAN generator with respect to the rest of the North-Western American Power System and the CHOLLA# generator with respect to the SOWARO station. In the BOARDMAN system, we show that there are three Hopf bifurcations at practical compensation values, while in the CHOLLA#4 system, we show that there is only one Hopf bifurcation. The results show that as the compensation level increases, the operating condition loses stability with a complex conjugate pair of eigenvalues of the Jacobian matrix crossing transversely from the left- to the right-half of the complex plane, signifying a Hopf bifurcation. As a result, the power system oscillates subsynchronously with a small limit-cycle attractor. As the compensation level increases, the limit cycle grows and then loses stability via a secondary Hopf bifurcation, resulting in the creation of a two-period quasiperiodic subsynchronous oscillation, a two-torus attractor. On further increases of the compensation level, the quasiperiodic attractor collides with its basin boundary, resulting in the destruction of the attractor and its basin boundary in a bluesky catastrophe. Consequently, there are no bounded motions. When a damper winding is placed either along the q-axis, or d-axis, or both axes of the BOARDMAN system and the machine saturation is considered in the CHOLLA#4 system, the study shows that, there is only one Hopf bifurcation and it occurs at a much lower level of compensation, indicating that the damper windings and the machine saturation destabilize the system by inducing subsynchronous resonance. Finally, we investigate the effect of linear and nonlinear controllers on mitigating subsynchronous resonance in the CHOLLA#4 system . The study shows that the linear controller increases the compensation level at which subsynchronous resonance occurs and the nonlinear controller does not affect the location and type of the Hopf bifurcation, but it reduces the amplitude of the limit cycle born as a result of the Hopf bifurcation. / Ph. D.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24295号 / 工博第5068号 / 新制||工||1791(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 CRUZ Ana Maria, 教授 渦岡 良介, 教授 肥後 陽介 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The discovery of antibiotics has been considered as one of the most remarkable scientific accomplishments of the last century. However, the extensive usage of antibiotics has led to the rapid emergence of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB), which have been recognized as one of the biggest threats to human and environmental health. While ARGs and ARB are ubiquitous in diverse environments, aquatic environments play a particularly crucial role in their prevalence and dissemination. Furthermore, the microbial complexity and various pollutants persisting in aquatic environments significantly contribute to the evolution and spread of ARGs and ARB. However, the knowledge regarding the distribution pattern of ARGs on a large scale, as well as the interaction between microbial community, specific pollutants, and ARGs and ARB, is currently limited. In this study, I conducted systematic work at multiple scales, to fill crucial knowledge gaps that could support the future management of the spread of antimicrobial resistance. In particular, on the ecosystems level I depict the biogeographical patterns of ARGs in freshwater reservoirs, on the community level I explored the selection patterns of combinations of antibiotics on multidrug resistant strains in complex community context, and finally, on the population level I investigated the impact of cigarette smoke, and waste products on the dissemination of ARGs. In my first study, samples were collected from 24 freshwater reservoirs across southeast China and the biogeographical patterns of bacterial communities and ARG profile were characterized using 16S rRNA gene high-throughput sequencing and high-throughput-quantitative PCR. A distance-decay pattern for both, microbial communities and ARG profiles, were observed. However, larger differences between reservoir ARG profiles than microbial community compositions were detected. Further, I found that the biogeographical patterns of bacterial communities were simultaneously driven by stochastic and deterministic processes, while ARG profiles were not explained by stochastic processes, and the relationship between bacterial communities and ARG profiles was weak. In summary, this study indicated a decoupling of bacterial community composition and ARG profiles in inland waters under relatively low-human-impact at a large scale. In a second study, the selection dynamics for multidrug resistance between isogenic pairs of E. coli strains under exposure to multiple selective agents in the absence and presence of the microbial community were investigated using microcosm experiments. The presence of the community significantly decreased the selection for multidrug resistant strain under exposure to a single antibiotic. While pressure through the second antibiotic significantly decreased the activity and diversity of the community, its ability to reduce selection was consistently maintained at levels comparable to those recorded in the absence of the second antibiotic. This indicates that the observed effects of community context on selection dynamics are rather based on competitive or protective effects between the focal strains and a small proportion of bacteria within the community, than on general competition for nutrients. Last but not least, the effect of cigarette-derived pollutants on the proliferation of ARGs was explored using multifaced approaches. Cigarette smoke condensate in an artificial lung sputum medium significantly elevated the transfer rates of a multi-drug-resistance encoding plasmid between Pseudomonas strains. The overproduction of reactive oxygen species (ROS) as part of the bacterial stress response was directly connected to the increasing transfer rates. Similarly, cigarette ash leachate in an environmental medium significantly increased the plasmid transfer rates, and overproduction of ROS was equally detected. Furthermore, used cigarette filters with entrapped toxicants were submerged in a wastewater stream and colonized by distinct microbial communities compared to those colonizing unused control filters. The microbial communities colonizing used cigarette filters were significantly enriched in AMR, potential pathogenic bacteria and mobile genetic elements. Overall, the insights gained within this thesis into the spread of AMR at multiple scales constitute a valuable contribution to support future management and monitoring of ARGs in diverse ecosystems.

A parametric identification procedure is proposed that combines the method of multiple scales and higher-order statistics to efficiently and accurately model nonlinear systems. A theoretical background for the method of multiple scales and higher-order statistics is given. Validation of the procedure is performed through applying it to numerical simulations of two nonlinear systems. The results show how the procedure can successfully characterize the system damping and nonlinearities and determine the corresponding parameters. The procedure is then applied to experimental measurements from two structural systems, a cantilevered beam and a three-beam frame. The results show that quadratic damping should be accounted for in both systems. Moreover, for the three-beam frame, the parametric excitation is much more important than the direct excitation. To show the flexibility of the procedure, numerical simulations of ship motion under parametric excitation are used to determine nonlinear parameters govening the relation between pitch, heave, and roll motions. The results show a high level of agreement between the numerical simulation and the mathematical model with the identified parameters. / Master of Science

For marine fishes, the early larval phase is considered a critical stage for survivorship and recruitment. The spatial and temporal dynamics of larval fish assemblages can influence their success and trophic structure of marine communities and entire ecosystems. This thesis will provide the first characterization of larval fish assemblage in the Strait of Georgia (SoG) in terms of diversity, abundance and composition, and their variability over multiple temporal scales, as well as the first quantification of variability in larval fish distribution in the SoG across multiple spatial scales. On the interdecadal scale, a significant decrease in larval abundance of several dominant fish taxa (Pacific hake, walleye Pollock, northern smoothtongue and rockfishes) contributed to a decline in total larval abundance and turnover in the composition structure between the early 1980s and the late 2000s. In contrast, both abundance and the relative composition of flatfishes and several demersal forage fish taxa increased during the same period. On interannual scales, abundance, diversity and community structure of the spring larval assemblages varied dramatically through 2007-2010, a period which alternated between strong La Niña and El Niño events. Higher overall larval concentrations were associated with warm conditions in the SoG in 2007 and 2010, while the lowest larval concentration was associated with cooler condition in 2009. Examination of associations between larval fish assemblages and environmental fluctuations suggests a potential influence of large-scale climate processes between the early 1980s and the late 2000s, but a primary association with local environmental factors on interannual scales. Spatial patterns in larval density of three dominant fish taxa (Pacific herring, Pacific hake and northern smoothtongue) were mostly structured on predefined broad (> 40km) and medium (20~40km) scales. Although their scale-dependent associations with environmental factors varied interannually, larval distributions in the central-southern SoG were generally associated with salinity, temperature and vertical stability of water column in the upper layer (0-50m). Our results emphasize the role of local estuarine circulation in structuring hierarchical spatial distributions of planktonic fish larvae in the SoG. These findings will provide considerable implications in fisheries resource management and conservation strategies. / Graduate / 0416 / 0329 / guanlu129@gmail.com

This thesis deals with the study of two problems in the area of nonlinear dynamics using the method of multiple scales. Accordingly, it consists of two parts. In the first part of the thesis, we explore the asymptotic stability of a planar two-degree- of-freedom robot with two rotary (R) joints following a desired trajectory under feedback control. Although such robots have been extensively studied and there exists stability and other results for position control, there are no analytical results for asymptotic stability when the end of the robot or its joints are made to follow a time dependent trajectory. The nonlinear dynamics of a 2R planar robot, under a proportional plus derivative (PD) and a model based computed torque control, is studied. The method of multiple scales is applied to the two nonlinear second-order ordinary deferential equations which describes the dynamics of the feedback controlled 2R robot. Amplitude modulation equations, as a set of four first order equations, are derived. At a fixed point, the Routh-Hurwitz criterion is used to obtain positive values of proportional and derivative gains at which the controller is asymptotically stable or indeterminate. For the model based control, a parameter representing model mismatch is incorporated and again controller gains are obtained, for a chosen mismatch parameter value, where the controller results in asymptotic stability or is indeterminate. From numerical simulations with gain values in the indeterminate region, it is shown that for some values and ranges of the gains, the non- linear dynamical equations are chaotic and hence the 2R robot cannot follow the desired trajectory and be asymptotically stable. The second part of the thesis deals with the study of the nonlinear dynamics of a rotating flexible link, modeled as a one dimensional beam, undergoing large deformation and with geometric nonlinearities. The partial deferential equation of motion is discretized using a finite element approach to yield four nonlinear, non-autonomous and coupled ordinary deferential equations. The equations are non-dimensional zed using two characteristic velocities – the speed of sound in the material and a speed associated with the trans- verse bending vibration of the beam. The method of multiple scales is used to perform a detailed study of the system. A set of four autonomous equations of the first-order are derived considering primary resonance of the external excitation with one of the natural frequencies of the model and one-to-one internal resonance between two different natural frequencies of the model. Numerical simulations show that for certain ranges of values of these characteristic velocities, the slow flow equations can exhibit chaotic motions. The numerical simulations and the results are related to a rotating wind turbine blade and the approach can be used for the study of the nonlinear dynamics of a single link flexible manipulator. The second part of the thesis also deals with the synchronization of chaos in the equations of motion of the flexible beam. A nonlinear control scheme via active nonlinear control and Lyapunov stability theory is proposed to synchronize the chaotic system. The proposed controller ensures that the error between the controlled and the original system asymptotically go to zero. A numerical example using parameters of a rotating power generating wind turbine blade is used to illustrate the theoretical approach.