In order to understand tidal circulation and oceanic current for the seas around Taiwan, this study use a baroclinic unstructured grid model to build a high resolution model. This model use semi-implicit method to solve the dynamic of ocean movement and larger time step can be used to calculate. Unstructured grid can be used to resolve complex coastline and variation of depth. TaiDBMv6 depth data were chosen to describe the depth distribution and grid mesh size were determined by local depth, minimum mesh size is about 0.75 minutes, and maximum 13 minutes. Tidal boundaries use 8 constituents derived from FES2004 and calibrated with 34 tide station records. Data of 2009 were used to evaluate the model results. The average of all station root mean square error was 10.1 cm. Station at east side of Taiwan have smaller errors, which almost lower than 5 cm. The maximum error can be found inside Taiwan Strait, about 25cm, mainly caused by lack of depth data near the coastal area. For oceanic current model, GFS and NFS-MC CWB wind forecast were used as meteorology input. Initial fields and boundary condition are derived from HYCOM results. Nudging of salinity and temperature also were used to stabilize the model. Transport of Kuroshio of 2009 is about 17.0¡Ó3.2Sv. Maximum value is about 28.6Sv, occurred in summer. Minimum value is about 8.3Sv, occurred in winter.

In the last twenty years, Google had a tremendous growth, from a small project of two PhD students to one of the most valuable companies on the globe. This growth is characterised by the versatile of the company, next to its search engine, Google explored many different value chains along the way. In this study, the value grid model is used to examine their movements. It can be stated that Google used, and uses, the paths/dimension as implied by Pil and Holweg (2006) to explore new opportunity and demand. The main reason why Google is able to do so is because of its board and management, who are innovative, and open-minded. Next to the top management is the appearance of Google in many different sectors and value chains a reason of their growth. The variety in businesses allows them to create a “Google experience”, and thus a competitive advantage in comparison with their main competitors who do not have this ability.

abstract: Substation ground system insures safety of personnel, which deserves considerable attentions. Basic substation safety requirement quantities include ground grid resistance, mesh touch potential and step potential, moreover, optimal design of a substation ground system should include both safety concerns and ground grid construction cost. In the purpose of optimal designing the ground grid in the accurate and efficient way, an application package coded in MATLAB is developed and its core algorithm and main features are introduced in this work. To ensure accuracy and personnel safety, a two-layer soil model is applied instead of the uniform soil model in this research. Some soil model parameters are needed for the two-layer soil model, namely upper-layer resistivity, lower-layer resistivity and upper-layer thickness. Since the ground grid safety requirement is considered under the earth fault, the value of fault current and fault duration time are also needed. After all these parameters are obtained, a Resistance Matrix method is applied to calculate the mutual and self resistance between conductor segments on both the horizontal and vertical direction. By using a matrix equation of the relationship of mutual and self resistance and unit current of the conductor segments, the ground grid rise can be calculated. Green's functions are applied to calculate the earth potential at a certain point produced by horizontal or vertical line of current. Furthermore, the three basic ground grid safety requirement quantities: the mesh touch potential in the worst case point can be obtained from the earth potential and ground grid rise; the step potential can be obtained from two points' earth potential difference; the grid resistance can be obtained from ground grid rise and fault current. Finally, in order to achieve ground grid optimization problem more accurate and efficient, which includes the number of meshes in the horizontal grid and the number of vertical rods, a novel two-step hybrid genetic algorithm-pattern search (GA-PS) optimization method is developed. The Genetic Algorithm (GA) is used first to search for an approximate starting point, which is used by the Pattern Search (PS) algorithm to find the final optimal result. This developed application provides an optimal grid design meeting all safety constraints. In the cause of the accuracy of the application, the touch potential, step potential, ground potential rise and grid resistance are compared with these produced by the industry standard application WinIGS and some theoretical ground grid model. In summary, the developed application can solve the ground grid optimization problem with the accurate ground grid modeling method and a hybrid two-step optimization method. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2014

The value grid model proposes a complex framework to analyse and understand value creatingactivities among different actors. This literature review is focusing on explaining the evolutionof the value grid model, thus explaining the following theories: (1) supply chain, (2) valuechain, (3) value system, (4) value network, (5) knowledge value chain, (6) value grid model.By underlining the significant changes in the level of business complexity, the importance forthe value grid model is explained. The model is based upon three dimensions, that when appliedcan enable a company to enhance its performance and leverage its own competitive advantage.

Modelagem de dois fluidos é largamente aplicada para simular escoamentos gássólido em risers de leitos fluidizados circulantes. As atuais simulações são de grandes clusters (SGC), executadas em domínios reais com malhas numéricas grosseiras, ou simulações sub-malha, executadas em malhas numéricas refinadas em domínios reduzidos. O propósito das simulações sub-malha é principalmente produzir dados de meso-escala a serem aplicados em simulações de grandes clusters. A atual literatura apresenta apenas umas poucas simulações sub -malha de escoamentos gás-sólido em risers aplicando modelagem de dois fluidos, todas para condições típicas de reatores de leito fluidizado circulante de craqueamento catalítico. Neste trabalho realizou-se uma simulação sub-malha para esta condição, e também para uma outra condição típica de reatores de leito circulante para combustão/gaseificação. Correlações teóricas derivadas da teoria cinética dos escoamentos granulares (TCEG) foram aplicadas para determinar a pressão e as viscosidades da fase sólida. Considerou-se um domínio de pequenas dimensões sob condições de contorno periódicas, aplicando-se malhas numéricas refinadas. Os resultados das simulações foram comparados entre si, com outros resultados de simulação de literatura, e com dados experimentais. Então, a correção das simulações foi abordada em vista dos dados empíricos disponíveis. / Two-fluid modeling is widely applied to simulate gas-solid flows in risers of circulating fluidized beds. Current simulations are either large cluster simulations (LCS), performed in real domains under coarse numerical meshes, or sub-grid simulations, performed in reduced domains under refined numerical meshes. The purpose of subgrid simulation is mostly to provide meso-scale data to be applied in large cluster simulations. The up to date literature presents only a few sub -grid simulations of gassolid flows in risers applying two-fluid modeling, all of them for conditions typical of catalytic cracking circulating fluidized bed reactors. In the present work a sub-grid simulation was performed for this condition, as well as for a condition typical of circulating fluidized bed coal combustion/gasification reactors. Theoretical correlations derived from the kinetic theory of granular flows (KTGF) were applied to determine pressure and viscosities of the solid phase. A small size domain was considered under periodic boundary conditions, and a refined numerical mesh was applied. The results of the simulations were compared to each other, to other literature results of simulation, and to experimental data. Then, the accuracy of the simulations was addressed in view of the available empirical data.

A generic formulation for modeling the sub-grid combustion in compressible, high Reynolds number, two-phase, reacting flows has been developed and validated. A sub-grid mixing/combustion model called Linear Eddy Mixing (LEM) model has been extended to compressible flows and used inside the framework of Large Eddy Simulation (LES) in this LES-LEM approach. The LES-LEM approach is based on the proposition that the basic mechanistic distinction between the convective and the molecular effects should be preserved for accurate prediction of the complex flow-fields such as those encountered in many combustion systems. In LES-LEM, all the physical processes such as molecular diffusion, small and large scale turbulent convection and chemical reaction are modeled separately but concurrently at their respective time scales. This multi-scale phenomena is solved using a two-scale numerical approach, wherein molecular diffusion, small scale turbulent convection and chemical reaction are grouped as small scale processes and the convection at the (LES grid) resolved scales are deemed as the large scale processes. Small-scale processes are solved using a hybrid finite-difference Monte-carlo type approach in a one-dimensional domain. Large-scale advection on the three-dimensional LES grid is modeled in a Lagrangian manner that conserves mass. Liquid droplets (represented by computational parcels) are tracked using the Lagrangian approach wherein the Newton's equation of motion for the discrete particles are integrated explicitly in the Eulerian gas field. Drag effects due to the droplets on the gas phase and the heat transfer between the gas and the liquid phase are explicitly included. Thus, full coupling is achieved between the two phases in the simulation. Validation of the compressible LES-LEM approach is conducted by simulating the flow-field in an operational General Electric Power Systems' combustor (LM6000). The results predicted using the proposed approach compares well with the experiments and a conventional (G-equation) thin-flame model. Particle tracking algorithms used in the present study are validated by simulating droplet laden temporal mixing layers. Comparison of the energy growth in the fundamental and sub-harmonic mode in the presence and absence of the droplets shows excellent agreement with spectral DNS. Finally, to test the ability of the present two-phase LES-LEM in simulating partially premixed combustion, a LES of freely propagating partially premixed flame in a droplet-laden isotropic turbulent field is conducted. LES-LEM along with the spray models correctly captures the flame structure in the partially premixed flames. It was found that most of the fuel droplets completely vaporize before reaching the flame, and hence provides a continuous supply of reactants, which results in an intense reaction zone similar to a premixed flame. Some of the droplets that did not evaporate completely, traverse through the flame and vaporize suddenly in the post flame zone. Due to the strong spatial variation of equivalence ratio a broad flame similar to a premixed flame is realized. Triple flame structure are also observed in the flow-field due to the equivalence ratio fluctuations.

Après avoir présenté les différentes méthodes de mesures des paramètres de propagation dans les câbles d’énergie électrique, nous justifions notre choix de faire la mesure de ces paramètres jusqu'à 100 MHz à l’aide d’un impédance-mètre. Nous validons ensuite la méthode de mesures et d’estimations des différents paramètres sur un câble de référence (câble 50 Ω). Cette phase nous a conduits à développer une méthode originale d’estimation des paramètres de propagation qui permet de s’affranchir des artefacts de mesures. Nous présentons ensuite une étude comparative sur des câbles secteurs répondant aux mêmes normes électriques. Cette étude met en évidence la variabilité des paramètres de propagation : d’un fabricant à l’autre (utilisation de diélectriques différents), pour des types de conducteurs différents (rigide : U1000 R02V versus flexible : H07VVF), pour des sections différentes (1.5 mm² et 2.5 mm²). Pour une modélisation optimale, on doit disposer des paramètres de propagation des câbles propres à l’installation étudiée. De plus, ces paramètres ne doivent pas être modifiés lors de l’installation (à proximité d’un conducteur : chemin de câble, en effectuant des boucles,…).La dernière partie commence par présenter les différents types de bruits présents sur le canal CPL (bruits temporels et bruits fréquentiels). Cette partie nous permet de présenter une méthode originale d'estimation du bruit de fond du canal moins sensible aux brouilleurs fréquentiels. Nous comparons, ensuite, les mesures de propagations de signaux effectuées sur plusieurs réseaux simples avec des résultats de simulation (utilisation de matrices de chaîne). Cette comparaison valide la méthode de mesures et d’estimation des paramètres de propagations, ainsi que la modélisation d’un réseau électrique simple. Enfin cette étude montre les limites de cette modélisation dans le cas d’une installation réelle. En effet, elle ne prend pas en compte par exemple : les « paramètres d’installations », ni les phénomènes de rayonnement. / After presenting the different methods to measure the power line cables propagation parameters, we justify our choice to measure these parameters up to 100 MHz using an impedance meter. Then, we validate the method of measurements and estimate these parameters on a reference cable (50 Ω cable). This phase has led us to develop a novel method for estimating propagation parameters that can overcome the measure artifacts. Afterwards, we present a comparative study on power line cable responding to the same electrical standards. This study highlights the variability of propagation: one manufacturer to another (using different dielectric), for different types (rigid versus flexible: U1000 R02V / H07 VVF) for different sections (1.5 mm² 2.5 mm²). For an optimal model is therefore essential to have the propagation parameters for the specific cable installation studied. Moreover, the grid should not be changed during installation (near the driver: cable trays, performing loops ...).The final section begins by presenting the different types of noise present on the PLC channel (time-domain and frequency-domain noise). This part allows us to present an original method for estimating the background noise of the channel less sensitive to frequency-jammers. We compare measurements on several simple network topologies with simulation results (using chain matrices). This comparison allows us to validate the method of measurement, the power line cable propagation parameter estimation, and a simple grid model. Finally, this study shows the limits of this model in the case of an actual installation. Indeed, it does not take into account e.g. the “installation parameters” or the phenomena of radiation.

Modelagem de dois fluidos é largamente aplicada para simular escoamentos gássólido em risers de leitos fluidizados circulantes. As atuais simulações são de grandes clusters (SGC), executadas em domínios reais com malhas numéricas grosseiras, ou simulações sub-malha, executadas em malhas numéricas refinadas em domínios reduzidos. O propósito das simulações sub-malha é principalmente produzir dados de meso-escala a serem aplicados em simulações de grandes clusters. A atual literatura apresenta apenas umas poucas simulações sub -malha de escoamentos gás-sólido em risers aplicando modelagem de dois fluidos, todas para condições típicas de reatores de leito fluidizado circulante de craqueamento catalítico. Neste trabalho realizou-se uma simulação sub-malha para esta condição, e também para uma outra condição típica de reatores de leito circulante para combustão/gaseificação. Correlações teóricas derivadas da teoria cinética dos escoamentos granulares (TCEG) foram aplicadas para determinar a pressão e as viscosidades da fase sólida. Considerou-se um domínio de pequenas dimensões sob condições de contorno periódicas, aplicando-se malhas numéricas refinadas. Os resultados das simulações foram comparados entre si, com outros resultados de simulação de literatura, e com dados experimentais. Então, a correção das simulações foi abordada em vista dos dados empíricos disponíveis. / Two-fluid modeling is widely applied to simulate gas-solid flows in risers of circulating fluidized beds. Current simulations are either large cluster simulations (LCS), performed in real domains under coarse numerical meshes, or sub-grid simulations, performed in reduced domains under refined numerical meshes. The purpose of subgrid simulation is mostly to provide meso-scale data to be applied in large cluster simulations. The up to date literature presents only a few sub -grid simulations of gassolid flows in risers applying two-fluid modeling, all of them for conditions typical of catalytic cracking circulating fluidized bed reactors. In the present work a sub-grid simulation was performed for this condition, as well as for a condition typical of circulating fluidized bed coal combustion/gasification reactors. Theoretical correlations derived from the kinetic theory of granular flows (KTGF) were applied to determine pressure and viscosities of the solid phase. A small size domain was considered under periodic boundary conditions, and a refined numerical mesh was applied. The results of the simulations were compared to each other, to other literature results of simulation, and to experimental data. Then, the accuracy of the simulations was addressed in view of the available empirical data.

The goal of this work is to further understand the relationships between porous electrode microstructure and mass transport properties. This understanding allows us to predict and improve cell performance from fundamental principles. The investigated battery systems are the widely used rechargeable Li-ion battery and the non-rechargeable alkaline battery. This work includes three main contributions in the battery field listed below. Direct Measurement of Effective Electronic Transport in Porous Li-ion Electrodes. An accurate assessment of the electronic conductivity of electrodes is necessary for understanding and optimizing battery performance. The bulk electronic conductivity of porous LiCoO2-based cathodes was measured as a function of porosity, pressure, carbon fraction, and the presence of an electrolyte. The measurements were performed by delamination of thin-film electrodes from their aluminum current collectors and by use of a four-line probe. Imaging and Correlating Microstructure To Conductivity. Transport properties of porous electrodes are strongly related to microstructure. An experimental 3D microstructure is needed not only for computation of direct transport properties, but also for a detailed electrode microstructure characterization. This work utilized X-ray tomography and focused ion beam (FIB)/scanning electron microscopy (SEM) to obtain the 3D structures of alkaline battery cathodes. FIB/SEM has the advantage of detecting carbon additives; thus, it was the main tomography tool employed. Additionally, protocols and techniques for acquiring, processing and segmenting series of FIB/SEM images were developed as part of this work. FIB/SEM images were also used to correlate electrodes' microstructure to their respective conductivities for both Li-ion and alkaline batteries. Electrode Microstructure Metrics and the 3D Stochastic Grid Model. A detailed characterization of microstructure was conducted in this work, including characterization of the volume fraction, nearest neighbor probability, domain size distribution, shape factor, and Fourier transform coefficient. These metrics are compared between 2D FIB/SEM, 3D FIB/SEM and X-ray structures. Among those metrics, the first three metrics are used as a basis for SG model parameterization. The 3D stochastic grid (SG) model is based on Monte Carlo techniques, in which a small set of fundamental inter-domain parameters are used to generate structures. This allows us to predict electrode microstructure and its effects on both electronic and ionic properties.

The goal of this study is to determine the economic implications of incorporating intermittent renewable energy into current power systems. The study also considers how to achieve an optimal mix of generating assets with renewable power, as well as the costs and advantages of using renewable energy sources to reduce CO2 emissions. Furthermore, this study examines how renewable energy exacerbates the "missing money" problem, which is a critical problem in electricity market design. The last part of this research is devoted to the calibration of the hybrid electricity grid model. We adopt positive mathematical programming (PMP) to calibrate the quadratic cost function for fossil fuel power plants. The calibrated model enables us to better analyze the impact of renewable energy on the electricity market. We find that due to the intermittency of wind and solar power, renewable energy could replace part of the peak load capacity like gas turbines but is not able to replace most of the base load capacity like coal capacities. The unintended consequences are that to eliminate the coal base load capacity, other forms of baseload capacities such as nuclear or hydropower capacity are necessary to incorporate the intermittent renewable power. Moreover, the capacity factors of remained peak load capacities and newly built base load capacities declined. Further support policies for maintaining the capacity adequacy standard are necessary for a reliable hybrid electricity market. / Graduate / 2023-09-26