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Unity es un motor gráfico 3D muy versátil para la creación de aplicaciones con un fuerte componente visual. En NoSpoon tech lab estamos usando de base dicho motor para el desarrollo del prototipo 'Zombies Party', un juego donde los jugadores, en la misma habitación, deben eliminar a su oponente antes de que los demás lo hagan. El alumno deberá investigar e implementar una infraestructura de comunicación entre los distintos dispositivos móviles mediante bluetooth, si fuera posible. Si esta comunicación no fuera posible, deberá estudiar diferentes opciones y elegir la mejor de ellas. Dicha infraestructura debe permitir a un dispositivo, conectarse a ellos y efectuar operaciones de mensajeria, tanto punto a punto como broadcast a todos los dispositivos implicados en la partida.

Consulta en la Biblioteca ETSI Industriales (6200), [ES] En éste apartado vamos a realizar, por un lado, una introducción al objeto central de este proyecto: los Autómatas Celulares. Qué son, como se idearon, para qué se utilizan o como funcionan serán temas explicados en el apartado de Introducción. En el apartado Motivación y Justificación veremos el problema tratado en este proyecto y por qué es necesaria una solución. Finalmente, en el apartado antecedentes veremos las soluciones realizadas hasta ahora y por qué no son válidas para solucionar los problemas anteriormente expuestos.

[EN] Atomistic models are a very valuable simulation tool in the field of material science. Among them are the continuous cellular automata (CCA), which can simulate accurately the process of chemical etching used in micro-electro-mechanical-systems (MEMS) micromachining. Due to the CCA intrinsic atomistic nature, simulation results are obtained in the form of a cloud of points, so data visualization has been usually problematic. When using these models as a part of a computer aided design tool, good data visualization is very important. In this paper, a minimum energy model implemented with the level set (LS) method for improving the visual representation of simulated MEMS is presented. Additionally, the sparse field method has been applied to reduce the high computational cost of the original LS. Finally, some reconstructed surfaces with completely different topologies are presented, proving the effectiveness of our implementation and the fact that it is capable of producing any real surface, flat and smooth ones.

[ES] En el presente trabajo se ha implementado el método Level Set (LS) para poder ser aplicado para simular el proceso de atacado anisótropo húmedo utilizado para la fabricación de microestructuras. En la actualidad para simular este proceso se utilizan modelos atomísticos, no obstante, el uso del método LS podía suponer ciertas ventajas. Finalmente, se comparan los resultados de ambas implementaciones., [EN] In this thesis it has been implemented the Level Set (LS) method in order to simulate anisotropic wet etching process used for building micro-structures. Now a days, it is used atomistic models to simulate this process, however, using the LS method could turn out in some advantages. Finally, results of both implementations are compared.

The use of atomistic methods, such as the continuous cellular automaton (CCA), is currently regarded as an accurate and efficient approach for the simulation of anisotropic etching in the development of micro-electro-mechanical systems (MEMS). However, whenever the targeted etching condition is modified (e. g. by changing the substrate material, etchant type, concentration and/or temperature) this approach requires performing a time-consuming recalibration of the full set of internal atomistic rates defined within the method. Based on the level set (LS) approach as an alternative and using the experimental data directly as input, we present a fully operational simulator that exhibits similar accuracy to the latest CCA models. The proposed simulator is tested by describing a wide range of silicon and quartz MEMS structures obtained in different etchants through complex processes, including double-sided etching as well as different mask patterns during different etching steps and/or simultaneous masking materials on different regions of the substrate. The results demonstrate that the LS method is able to simulate anisotropic etching for complex MEMS processes with similar computational times and accuracy as the atomistic models.

The use of atomistic methods, such as the Continuous Cellular Automaton (CCA), is currently regarded as a computationally efficient and experimentally accurate approach for the simulation of anisotropic etching of various substrates in the manufacture of Micro-electro-mechanical Systems (MEMS). However, when the features of the chemical process are modified, a time-consuming calibration process needs to be used to transform the new macroscopic etch rates into a corresponding set of atomistic rates. Furthermore, changing the substrate requires a labor-intensive effort to reclassify most atomistic neighborhoods. In this context, the Level Set (LS) method provides an alternative approach where the macroscopic forces affecting the front evolution are directly applied at the discrete level, thus avoiding the need for reclassification and/or calibration. Correspondingly, we present a fully-operational Sparse Field Method (SFM) implementation of the LS approach, discussing in detail the algorithm and providing a thorough characterization of the computational cost and simulation accuracy, including a comparison to the performance by the most recent CCA model. We conclude that the SFM implementation achieves similar accuracy as the CCA method with less fluctuations in the etch front and requiring roughly 4 times less memory. Although SFM can be up to 2 times slower than CCA for the simulation of anisotropic etchants, it can also be up to 10 times faster than CCA for isotropic etchants. In addition, we present a parallel, GPU-based implementation (gSFM) and compare it to an optimized, multicore CPU version (cSFM), demonstrating that the SFM algorithm can be successfully parallelized and the simulation times consequently reduced, while keeping the accuracy of the simulations. Although modern multicore CPUs provide an acceptable option, the massively parallel architecture of modern GPUs is more suitable, as reflected by computational times for gSFM up to 7.4 times faster than f

The parallelization of the finite-difference time-domain (FDTD) method for room acoustic simulation using graphic processing units (GPUs) has been subject of study even prior to the introduction of GPGPU (general-purpose computing on GPUs) environments such as the compute unified device architecture (CUDA) from Nvidia. A mature architecture nowadays, CUDA offers enough flexibility and processing power to obtain important performance gains with naively ported serial CPU codes. However, careful implementation of the algorithm and appropriate usage of the different subsystems a GPU offers can lead to even further performance improvements. In this paper, we present a detailed study between different approaches to the parallelization of the FDTD method applied to room acoustics modelling, and we describe several optimization guidelines to improve the computation speed when using single precision and double precision floating point model data, nearly doubling the performance obtained by previously published implementations. (C) 2011 Elsevier Ltd. All rights reserved.

Anisotropic wet chemical etching of quartz is a bulk micromachining process for the fabrication of micro-electro-mechanical systems (MEMS), such as resonators and temperature sensors. Despite the success of the continuous cellular automaton for the simulation of wet etching of silicon, the simulation of the same process for quartz has received little attention-especially from an atomistic perspective-resulting in a lack of accurate modeling tools. This paper analyzes the crystallographic structure of the main surface orientations of quartz and proposes a novel classification of the surface atoms as well as an evolutionary algorithm to determine suitable values for the corresponding atomistic removal rates. Not only does the presented evolutionary continuous cellular automaton reproduce the correct macroscopic etch rate distribution for quartz hemispheres, but it is also capable of performing fast and accurate 3D simulations of MEMS structures. This is shown by several comparisons between simulated and experimental results and, in particular, by a detailed, quantitative comparison for an extensive collection of trench profiles. © 2012 IOP Publishing Ltd.

An evolutionary algorithm is presented for the automated calibration of the continuous cellular automaton for the simulation of isotropic and anisotropic wet chemical etching of silicon in as many as 31 widely different and technologically relevant etchants, including KOH, KOH+IPA, TMAH and TMAH+Triton, in various concentrations and temperatures. Based on state-of-the-art evolutionary operators, we implement a robust algorithm for the simultaneous optimization of roughly 150 microscopic removal rates based on the minimization of a cost function with four quantitative error measures, including (i) the error between simulated and experimental macroscopic etch rates for numerous surface orientations all over the unit sphere, (ii) the error due to underetching asymmetries and floor corrugation features observed in simulated silicon samples masked using a circular pattern, (iii) the error associated with departures from a step-flow-based hierarchy in the values of the microscopic removal rates, and (iv) the error associated with deviations from a step-flow-based clustering of the microscopic removal rates. For the first time, we present the calibration and successful simulation of two technologically relevant CMOS compatible etchants, namely TMAH and, especially, TMAH+Triton, providing several comparisons between simulated and experimental MEMS structures based on multi-step etching in these etchants.

Current PET systems with fully digital trigger rely on early digitization of detector signals and the use of digital processors, usually FPGAs, for recognition of valid gamma events on single detectors. Timestamps are assigned and later used for coincidence analysis. In order to maintain a decent timing resolution for events detected on different acquisition boards, it is necessary that local timestamps on different FPGAs be synchronized. Sub-nanosecond accuracy is mandatory if we want this effect to be negligible on overall timing resolution. This is usually achieved by connecting all boards to a common backplane with a precise clock delivery network; however, this approach forces a rigid structure on the whole PET system and may pose scalability problems. © 2006 IEEE.

Presently, dynamic surface-based models are required to contain increasingly larger numbers of points and to propagate them over longer time periods. For large numbers of surface points, the octree data structure can be used as a balance between low memory occupation and relatively rapid access to the stored data. For evolution rules that depend on neighborhood states, extended simulation periods can be obtained by using simplified atomistic propagation models, such as the Cellular Automata (CA). This method, however, has an intrinsic parallel updating nature and the corresponding simulations are highly inefficient when performed on classical Central Processing Units (CPUs), which are designed for the sequential execution of tasks. In this paper, a series of guidelines is presented for the efficient adaptation of octree-based, CA simulations of complex, evolving surfaces into massively parallel computing hardware. A Graphics Processing Unit (GPU) is used as a cost-efficient example of the parallel architectures. For the actual simulations, we consider the surface propagation during anisotropic wet chemical etching of silicon as a computationally challenging process with a wide-spread use in microengineering applications. A continuous CA model that is intrinsically parallel in nature is used for the time evolution. Our study strongly indicates that parallel computations of dynamically evolving surfaces simulated using CA methods are significantly benefited by the incorporation of octrees as support data structures, substantially decreasing the overall computational time and memory usage. © 2010 Elsevier B.V. All rights reserved.

Coincidence time resolution is one of the most important issues in PET detectors. Improving this resolution is required to increase the noise equivalent count rate (NECR) that reduces the noise in the reconstructed images. The aim of this work is to evaluate the behavior and time resolution of different proposed time pick-off algorithms in order to select the best configuration for our PET system. The experimental setup used for this research is composed by two monolithic LSO crystals+ PSPMT detectors and an FPGA based PET data acquisition system (DAQ). The acquired signals are sampled using a 12-bit 70 MHz analog to digital converter (ADC) per channel. The setup has no centralized electronics for trigger and event time extraction. Consequently, events for each detector head are processed independently and all the signals are acquired in the same way. Time resolution in this kind of systems can be improved by means of digital processing techniques and using different shapings for the last dynode signals. Four digital algorithms extracting time information from the acquired pulses have been evaluated: (1) Amplitude bipolar digital constant fraction discriminator (BCFD), (2) charge BCFD, (3) interpolated amplitude BCFD and (4) interpolated charge BCFD. Two different architectures for the interpolation algorithm have been used (one-sample and two-sample interpolation), which allow us to work with two different FPGA internal sampling frequencies: 140 MHz and 210 MHz. The results show the importance of selecting the right algorithm and parameters. Time coincidence resolution in our hardware system can be improved by up to 6.9 ns FWHM depending on the chosen digital algorithm programmed on the FPGA. The measurements with our setup reveal that charge based algorithms are less sensitive to signal noise and generate better results than amplitude algorithms. The best configuration achieves a FWHM resolution close to 1.8 ns. © 2006 IEEE.

This is part I of a series of two papers dedicated to the presentation of a novel, large throughput, experimental procedure to determine the three-dimensional distribution of the etch rate of silicon in a wide range of anisotropic etchants, including a total of 30 different etching conditions in KOH, KOH+IPA, TMAH and TMAH+Triton solutions at various concentrations and temperatures. The method is based on the use of previously reported, vertically micromachined wagon wheels (WWs) (Wind and Hines 2000 Surf. Sci. 460 21-38; Nguyen and Elwenspoek 2007 J. Electrochem. Soc. 154 D684-91), focusing on speeding up the etch rate extraction process for each WW by combining macrophotography and image processing procedures. The proposed procedure positions the WWs as a realistic alternative to the traditional hemispherical specimen. The obtained, extensive etch rate database is used to perform wet etching simulations of advanced systems, showing good agreement with the experimental counterparts. In part II of this series (Gosalvez et al J. Micromech. Microeng. 21 125008), we provide a theoretical analysis of the etched spoke shapes, a detailed comparison to the etch rates from previous studies and a self-consistency study of the measured etch rates against maximum theoretical values derived from the spoke shape analysis.

As a sequel to part I (Gosalvez et al J. Micromech. Microeng. 12 125007), the present paper is part II of a series of two papers dedicated to the presentation of a novel, large-throughput, experimental procedure to determine the complete three-dimensional orientation dependence of the etch rate of silicon by using vertically micromachined wagon wheel samples. While the first part provides the experimental details and compares the results to realistic simulations, the present paper focuses on characterizing the reliability of the obtained etch rates. For this purpose, the shape of the etched structures is analyzed and corresponding formulas are derived, enabling the estimation of an upper bound to the measured etch rates. It is shown that the measured etch rates remain below this limit, strongly indicating that the observed wedge retraction values are consistent with the assumed geometrical shape of the wedges. An exception to this rule are the etch rates of {1 1 0} obtained from < 1 1 0 >-oriented wafers, which are systematically larger. This deviation is explained by a kinetic acceleration process due to the small size of the step-flow structures that are formed on the affected wagon wheel spokes. The comparison to previous experiments indicates that the proposed method provides similar or even more accurate etch rates for some of the etchants with a more affordable and less labor-intensive approach.

Las Estructuras Celulares Paralelas (ECP) son una herramienta eficaz en el modelado de ciertos sistemas dinámicos. Debido a la naturaleza de las ECP, su implementación en un PC es altamente ineficiente. En este trabajo se presenta un lenguaje de definición de ECP, un compilador y una aplicación gráfica que permiten implementar ECPs en FPGAs.

[EN] A novel CMOS integrated front-end architecture is presented throughout this paper. It is designed to be used with detectors based on continuous scintillation crystals plus position sensitive photomultiplier. Its structure aims at carrying out an analog computation which extracts fundamental information of the detected event. This fact allows us to avoid an individual acquisition of every input channel so that a large increase of inputs is feasible. In order to accomplish the processing task, a current buffer delivers a copy of each input signal to several computation blocks. Those processing units implement current mode analog filtering operations with a digitally programmable 8-bit precision coefficient for each front-end input. Output currents are summed and sent to the output stage where a buffered current output is provided. A voltage signal is also available by means of a rail-to-rail transresistance amplifier. The final goal is to obtain several moments of the light distribution on the detector surface. Each one provides useful information, such as energy, position, depth of interaction (from the light distribution width), skewness (deformation due to border effect), etc. Since the computation is purely additive, the current outputs can be used as inputs to other equal devices thus creating a fully expandable architecture.

La presente tesis toma como eje central el modelado de sistemas dinámicos mediante Autómatas Celulares (ACs). Los ACs permiten modelar un sistema enunciando el comportamiento microscópico a fin de obtener un comportamiento macroscópico correcto. Una de los principales campos donde esta metodología ha sido aplicada (y la cual forma otro de los puntos centrales de esta tesis) es el modelado del Grabado Anisótropo Húmedo (GAH). El GAH es un proceso químico el cual permite realizar microestructuras de silicio tridimensionales, lo que le ha permitido convertirse en una importante técnica de microfabricación. El GAH se utiliza para el micromaquinado de Sistemas Micro-Electro-Mecánicos (MEMS). Los MEMS consisten en la integración de elementos mecánicos, sensores, actuadores y electrónica en un substrato de silicio común a través de la tecnología de microfabricación. Los MEMS tienen una gran influencia en la industria puesto que dispositivos fabricados mediante esta tecnología se utilizan de forma intensiva en diversos campos tales como: sistemas de seguridad en automoción, sensores de movimiento en electrónica de consumo o inyectores en sistemas de impresión. El GAH es un proceso complejo cuyo resultado depende en gran medida de los diversos parámetros del proceso: (disolución, temperatura, tiempo), por lo que la utilización de un simulador previo a la realización del experimento puede suponer un gran ahorro en cuestión de tiempo y material. Los simuladores actuales de GAH basados en ACs poseen diversas limitaciones: Tiempos de computación muy elevados debido a los altos requisitos computacionales de los ACs, un reducido conjunto de calibraciones existentes, así como la imposibilidad de simular el GAH basado en nuevos atacantes tales como TMAH+Triton. La resolución de estas limitaciones es abordada en diversos capítulos de la tesis.