6 research outputs found

    Estudio de prestaciones de cargas de latencia crítica en sistemas SMT

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    [ES] La computación en la nube (cloud computing) ofrece servicios de computación bajo demanda a través de una red (habitualmente internet). Es un servicio ampliamente utilizado en la actualidad y, por tanto, existe una gran cantidad de trabajo centrado en el análisis y la mejora de prestaciones de este tipo de servicios. El presente proyecto se centra en cargas de latencia crítica, que son aquellas que deben garantizar una latencia máxima dentro de un umbral para evitar que los usuarios sufran una degradación de prestaciones, cuantificada en términos de calidad de servicio. Aplicaciones como los servicios de búsqueda, el reconocimiento de texto o imágenes y la consulta de bases de datos son aplicaciones de latencia crítica típicas. El presente proyecto propone analizar las prestaciones de este tipo de cargas cuando se ejecutan en un procesador con soporte para la ejecución simultanea de hilos (SMT) utilizando la herramienta perf para determinar las estructuras del procesador que principalmente limitan sus prestaciones.[EN] Cloud computing offers computing services on demand over a network (usually the internet). It is a widely used service today and, therefore, there is a large amount of work focused on the analysis and improvement of the benefits of this type of service. This project focuses on critical latency loads, which are those that must guarantee maximum latency within a threshold to prevent users from suffering a performance degradation, quantified in terms of quality of service. Applications such as search services, text or image recognition, and database queries are typical latency-critical applications. This project proposes to analyze the performance of this type of workloads when running on a simultaneous multithreading (SMT) processor using the perf tool to determine the processor structures that mainly limit their performance.Wu, D. (2021). Estudio de prestaciones de cargas de latencia crítica en sistemas SMT. Universitat Politècnica de València. http://hdl.handle.net/10251/164602TFG

    Speech Recognition

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    Chapters in the first part of the book cover all the essential speech processing techniques for building robust, automatic speech recognition systems: the representation for speech signals and the methods for speech-features extraction, acoustic and language modeling, efficient algorithms for searching the hypothesis space, and multimodal approaches to speech recognition. The last part of the book is devoted to other speech processing applications that can use the information from automatic speech recognition for speaker identification and tracking, for prosody modeling in emotion-detection systems and in other speech processing applications that are able to operate in real-world environments, like mobile communication services and smart homes

    Designs for increasing reliability while reducing energy and increasing lifetime

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    In the last decades, the computing technology experienced tremendous developments. For instance, transistors' feature size shrank to half at every two years as consistently from the first time Moore stated his law. Consequently, number of transistors and core count per chip doubles at each generation. Similarly, petascale systems that have the capability of processing more than one billion calculation per second have been developed. As a matter of fact, exascale systems are predicted to be available at year 2020. However, these developments in computer systems face a reliability wall. For instance, transistor feature sizes are getting so small that it becomes easier for high-energy particles to temporarily flip the state of a memory cell from 1-to-0 or 0-to-1. Also, even if we assume that fault-rate per transistor stays constant with scaling, the increase in total transistor and core count per chip will significantly increase the number of faults for future desktop and exascale systems. Moreover, circuit ageing is exacerbated due to increased manufacturing variability and thermal stresses, therefore, lifetime of processor structures are becoming shorter. On the other side, due to the limited power budget of the computer systems such that mobile devices, it is attractive to scale down the voltage. However, when the voltage level scales to beyond the safe margin especially to the ultra-low level, the error rate increases drastically. Nevertheless, new memory technologies such as NAND flashes present only limited amount of nominal lifetime, and when they exceed this lifetime, they can not guarantee storing of the data correctly leading to data retention problems. Due to these issues, reliability became a first-class design constraint for contemporary computing in addition to power and performance. Moreover, reliability even plays increasingly important role when computer systems process sensitive and life-critical information such as health records, financial information, power regulation, transportation, etc. In this thesis, we present several different reliability designs for detecting and correcting errors occurring in processor pipelines, L1 caches and non-volatile NAND flash memories due to various reasons. We design reliability solutions in order to serve three main purposes. Our first goal is to improve the reliability of computer systems by detecting and correcting random and non-predictable errors such as bit flips or ageing errors. Second, we aim to reduce the energy consumption of the computer systems by allowing them to operate reliably at ultra-low voltage level. Third, we target to increase the lifetime of new memory technologies by implementing efficient and low-cost reliability schemes

    Parallel Computing for Biological Data

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    In the 1990s a number of technological innovations appeared that revolutionized biology, and 'Bioinformatics' became a new scientific discipline. Microarrays can measure the abundance of tens of thousands of mRNA species, data on the complete genomic sequences of many different organisms are available, and other technologies make it possible to study various processes at the molecular level. In Bioinformatics and Biostatistics, current research and computations are limited by the available computer hardware. However, this problem can be solved using high-performance computing resources. There are several reasons for the increased focus on high-performance computing: larger data sets, increased computational requirements stemming from more sophisticated methodologies, and latest developments in computer chip production. The open-source programming language 'R' was developed to provide a powerful and extensible environment for statistical and graphical techniques. There are many good reasons for preferring R to other software or programming languages for scientific computations (in statistics and biology). However, the development of the R language was not aimed at providing a software for parallel or high-performance computing. Nonetheless, during the last decade, a great deal of research has been conducted on using parallel computing techniques with R. This PhD thesis demonstrates the usefulness of the R language and parallel computing for biological research. It introduces parallel computing with R, and reviews and evaluates existing techniques and R packages for parallel computing on Computer Clusters, on Multi-Core Systems, and in Grid Computing. From a computer-scientific point of view the packages were examined as to their reusability in biological applications, and some upgrades were proposed. Furthermore, parallel applications for next-generation sequence data and preprocessing of microarray data were developed. Microarray data are characterized by high levels of noise and bias. As these perturbations have to be removed, preprocessing of raw data has been a research topic of high priority over the past few years. A new Bioconductor package called affyPara for parallelized preprocessing of high-density oligonucleotide microarray data was developed and published. The partition of data can be performed on arrays using a block cyclic partition, and, as a result, parallelization of algorithms becomes directly possible. Existing statistical algorithms and data structures had to be adjusted and reformulated for the use in parallel computing. Using the new parallel infrastructure, normalization methods can be enhanced and new methods became available. The partition of data and distribution to several nodes or processors solves the main memory problem and accelerates the methods by up to the factor fifteen for 300 arrays or more. The final part of the thesis contains a huge cancer study analysing more than 7000 microarrays from a publicly available database, and estimating gene interaction networks. For this purpose, a new R package for microarray data management was developed, and various challenges regarding the analysis of this amount of data are discussed. The comparison of gene networks for different pathways and different cancer entities in the new amount of data partly confirms already established forms of gene interaction

    Study of interaction between indium species and DNA in the formation of DNA -templated nanowires

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    A primary goal of semiconductor industry is to improve device performance and capability by downscaling feature size and upscaling packaging density. As optical-lithography, the mainstream technology for microfabrication, is being stretched to its limit, new unconventional fabrication techniques are being explored as alternatives. A Bottom-up approach for manufacturing is emerging as an answer to limitations posed by the traditional Top-down approach. Nanowires, bearing the potential of being the basic building blocks for such an approach, are gaining tremendous attention in nanoelectronics. Metal nanowires fabricated using DNA as templates have potential for precise control of length, diameter and positioning. However, wires formed by assembly of metal nanostructures were found to have considerably high electrical resistivity. Oxide formation, irregular structure and formation of grain boundaries in metal nanostructure can be attributed to this problem. This dissertation is an investigation into factors that affect the formation of DNA templated indium nanowires. They could be treated thermally to increase overall electrical conductivity by utilizing the low melting point of the metal. We have used indium(0), (I) and (III) species as precursors to DNA metallization. Indium(0) in the form of nanoparticles was prepared by reducing indium(I) complex to indium(0). A organic complex {[HB(3-phpz)3]In} was synthesized to stabilize otherwise highly air-sensitive indium(I) species derived from cyclopentadine. Indium(III) species in the form of aqueous indium trichloride was also used. During the interaction studies of indium species with DNA, we found that indium(III) binds to DNA in aqueous medium inducing conformal changes and considerable coiling and condensation of DNA molecules, making it unsuitable for nanowire preparation. Indium nanoparticles did not selectively deposit on DNA, indicating that indium(0) has no specific affinity towards DNA molecules. However, reduction of {[HB(3-phpz)3]In} using sodium in the presence of DNA shows successful metallization of DNA. Even though laterally stretched wires with uniform diameter were not formed, selective deposition of indium metal on DNA, forming random network of metallized DNA bundles with diameters between 20-100 nm was accomplished. Preliminary investigation on electrical resistivity indicates that heat treatment of the nanowires reduces the resistivity of these wires by a factor of five. In the future, it will be possible to assemble nanowires with better orientation, higher uniformity and lower diameters by applying the knowledge gained during this study to already existing techniques of DNA templated nanowire assembly. Indium nanowires thus assembled can be feasibly heat-treated to achieve highly uniform structure with low resistively making it compatible as a component for futuristic nanocircuits

    Multiphoton Absorption Polymerization: Issues and Solutions

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    Multiphoton absorption polymerization (MAP) is gaining importance as a means for fabricating 3-D micro-devices. By focusing an ultrafast laser inside a prepolymer resin, radical polymerization can be initiated by two-photon absorption of a photoinitiator. The result is a highly cross-linked solid polymer point, or voxel, which is extended to create complex shapes by scanning the laser beam in a 3-D pattern. The geometric freedom combined with sub-micron resolution provided by MAP is unparalleled by any other microfabrication techniques. However, MAP suffers from three issues; the novelty of the technique itself, the fact that it is inherently a serial process, and the restriction of device materials to cross-linking polymers. To better understand the technique, the MAP fabrication setup is described in detail. Specific techniques of fabrication, such as how to design and wash microstructures, are also described. To address the second issue, micro-transfer molding (TM) has been applied to make high fidelity molds of complex master microstructures, followed by a fast and easy replication step to make duplicate structures. This technique has even been extended to replicate structures with closed-loops, such as arches or coils, which should be topologically impossible to mold and replicate. The third issue has been addressed in two ways, by laser-direct-writing of metal patterns on 3-D substrates and by changing the surface chemistry of the polymer to contain primary amines. Laser-deposited metal can be made conductive by further electroless growth yielding 3-D conducting patterns. The amine surface modification can be used for any number of chemistries, including catalytic metal seeding, which could then be grown into a metal coating. This new flexibility in surface chemistry, along with the enhanced speed of TM, ensures that MAP will be a practical technology to create micro-devices. Numerous electrical, mechanical, optical, and biological applications of MAP are described as well as potential future applications. To date this work has resulted in 9 peer reviewed publications, and 2 more which have recently been submitted
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