Una importante polémica musulmana en la Mallorca del siglo XI

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Solution of viscous flow problems by using the boundary element method

A scheme based on the Boundary Element Method (BEM) for solving the problem of steady flow of an incompressible viscous fluid is presented in this thesis. The problem is governed by both Navier-Stokes (N-S) equations and the continuity equation. The fundamental solution of the two-dimensional N-S is derived, and the partial differential equations are converted to an integral equation;The computer code is flexible enough to handle a variety of boundary and domain elements with different degrees of interpolation polynomial. Boundary and domain integrals over corresponding elements are evaluated analytically. The Newton Raphson iteration scheme accompanied by a relaxation factor is used to solve the nonlinear equations. The code includes a post processor that calculates the velocity components at any point inside the domain;The scheme has been applied to three test problems. The first concerns Couette flow, which has been used as a test case for testing the rate of convergence and accuracy. The second and the third concern the driven cavity and the flow in a stepped channel, respectively;In the integral equation formulation, the primary unknowns are tractions on the domain boundary and velocities in the interior. Because the shear stress, drag, and lift can be simply computed from the values of tractions along the boundary, such a formulation is markedly superior to either the finite-difference or the finite-element formulation. In customary pressure-velocity or streamfunction-vorticity formulations, employed in the finite-difference or finite-element methods, calculation of stress, drag, and lift involves extensive postprocessing

Image Classification on IoT Edge Devices: Profiling and Modeling

With the advent of powerful, low-cost IoT systems, processing data closer to where the data originates, known as edge computing, has become an increasingly viable option. In addition to lowering the cost of networking infrastructures, edge computing reduces edge-cloud delay, which is essential for mission-critical applications. In this thesis, we show the feasibility and study the performance of image classification using IoT devices. Specifically, we explore the relationships between various factors of image classification algorithms that may affect energy consumption such as dataset size, image resolution, algorithm type, algorithm phase, and device hardware. Our experiments show a strong, positive linear relationship between three predictor variables, namely model complexity, image resolution, and dataset size, with respect to energy consumption. In addition, in order to provide a means of predicting the energy consumption of an edge device performing image classification, we investigate the usage of three machine learning algorithms using the data generated from our experiments. The performance as well as the trade offs for using linear regression, Gaussian process, and random forests are discussed and validated. Our results indicate that the random forest model outperforms the two former algorithms, with an R-squared value of 0.95 and 0.79 for two different validation datasets

The Basal Ganglia as a Gate Control Mechanism for Postural Set

Impairment of righting reflexes is one of the cardinal features of basal ganglia disease. Although the precise anatomical organization of these reflexes in man is not fully understood, neurophysiological experiments suggest an important role for the striatum (i.e. caudate nucleus and putamen), pallidum, the supplementary motor area (SMA) and the motor and sensory cortices in righting reactions (see chapter 1-3)

TCP over CDMA2000 Networks: A Cross-Layer Measurement Study

Modern cellular channels in 3G networks incorporate sophisticated power control and dynamic rate adaptation which can have a significant impact on adaptive transport layer protocols, such as TCP. Though there exists studies that have evaluated the performance of TCP over such networks, they are based solely on observations at the transport layer and hence have no visibility into the impact of lower layer dynamics, which are a key characteristic of these networks. In this work, we present a detailed characterization of TCP behavior based on cross-layer measurement of transport, as well as RF and MAC layer parameters. In particular, through a series of active TCP/UDP experiments and measurement of the relevant variables at all three layers, we characterize both, the wireless scheduler in a commercial CDMA2000 network and its impact on TCP dynamics. Somewhat surprisingly, our findings indicate that the wireless scheduler is mostly insensitive to channel quality and sector load over short timescales and is mainly affected by the transport layer data rate. Furthermore, we empirically demonstrate the impact of the wireless scheduler on various TCP parameters such as the round trip time, throughput and packet loss rate

Developing Construction Materials from Recycled Composites, Recycled Materials, and Recycling Technologies

This paper reviews the state of technology in recycling of coal fly ash, metal, glass, plastic and composite materials has been conducted. This is closely related to our daily life, as recent estimates indicate that more than 33 million tons of plastic are discarded each year, of which 6.5% are recycled and 7.7% are burned. Similar amounts of materials are discarded every year, including glass, metal and fly ash. Although much research has been performed on the recycling technologies for different common waste materials, how to apply them in constructional field and how they performed in application are quite new, with studies that are rapidly increasing in recently due to China decided not to receive any materials waste from the US, which means a high portion of discarded materials nowhere to be placed. In addition, just choosing to dispose of waste materials by landfills not only causes new environmental pollution but also wastes available resources. Therefore, from different aspects, such as the basic properties of materials, the technical means of recycling, the applications, properties, and prices after recycling, this paper comprehensively depict the circulation of these five materials

Finite Element Analysis of Steel Quenching Process

The finite element method (FEM) is employed to investigate the residual stress state and the variation of internal stresses in the St5O cylinder bar quenched from 600 to O°C. Thermal analysis is first performed to obtain the cooling curves for the core and surface of the bar, this is followed by a full structural analysis. The results obtained from the computer simulation are compared with those experimentally determined values that are available in the literature and there appears to be a good measure of agreement. The study found that at the initial stages of the quenching process, the residual stresses were tensile at the surface and compressive in the core, however, towards the end of the quenching process, the tensile residual stresses switched to the core and compressive residual stresses at the surface

Fuzzy Rules Optimization in Fuzzy Expert System for Machinability Data Selection: Genetic Algorithms Approach

Machinability data selection is complex and cannot be easily formulated by any mathematical model to meet design specification. Fuzzy logic is a good approach to solve such problems. Fuzzy rules optimization is always a problems for a complex fuzzy rules from more than 10 thousand combinations. (Wong et aL 1997) developed fuzzy models for machinability data selection. There are more than 2 x 1029 possible sets of rules for each model. Situation would be more complicated if further increase the number of inputs and/or outputs. The fuzzy rules were selected by trial and error and intuition in reference (Wong et aL 1997). Genetic optimization is suggested in this paper to further optimizing the fuzzy rules optimization with genetic algorithms has been developed. Weighted centroid method is used for output defuzzi fication to save processing time. Comparisons between the results of the new models and the previously published literatures are made

Finite element analysis of sheet metal forming process

Minimization of response times and costs and maximization of the efficiency and quality in producing a product are imperative for survival in the competitive manufacturing industry. Sheet metal forming is a widely used and costly manufacturing process, to which these considerations apply. Aluminum sheet becomes favorable compare to steel regards to some improvement at aerodynamic designs, increased engine efficiency and fuel economy. Wide range of aluminum automotive product included doors, fenders, bumpers face bars, seat frames and roof panels have been produced. This paper was carried out to study the finite element (elastic-plastic) analysis of sheet metal forming process using the finite element software. LUSAS simulation was carried out to gain accurate and critical understanding of sheet forming process. Axisymmetry element mesh and plain strain element mesh were use incorporated with slideline features to model and study the sheet metal forming process. Simulation of elasticplastic behavior of aluminum sheet was carried out under non-linear condition to investigate sheet metal forming process