1,467 research outputs found

    Contextual Information Retrieval based on Algorithmic Information Theory and Statistical Outlier Detection

    Full text link
    The main contribution of this paper is to design an Information Retrieval (IR) technique based on Algorithmic Information Theory (using the Normalized Compression Distance- NCD), statistical techniques (outliers), and novel organization of data base structure. The paper shows how they can be integrated to retrieve information from generic databases using long (text-based) queries. Two important problems are analyzed in the paper. On the one hand, how to detect "false positives" when the distance among the documents is very low and there is actual similarity. On the other hand, we propose a way to structure a document database which similarities distance estimation depends on the length of the selected text. Finally, the experimental evaluations that have been carried out to study previous problems are shown.Comment: Submitted to 2008 IEEE Information Theory Workshop (6 pages, 6 figures

    Insights into tunnel FET-based charge pumps and rectifiers for energy harvesting applications

    Get PDF
    In this paper, the electrical characteristics of tunnel field-effect transistor (TFET) devices are explored for energy harvesting front-end circuits with ultralow power consumption. Compared with conventional thermionic technologies, the improved electrical characteristics of TFET devices are expected to increase the power conversion efficiency of front-end charge pumps and rectifiers powered at sub-µW power levels. However, under reverse bias conditions the TFET device presents particular electrical characteristics due to its different carrier injection mechanism. In this paper, it is shown that reverse losses in TFET-based circuits can be attenuated by changing the gate-to-source voltage of reverse-biased TFETs. Therefore, in order to take full advantage of the TFETs in front-end energy harvesting circuits, different circuit approaches are required. In this paper, we propose and discuss different topologies for TFET-based charge pumps and rectifiers for energy harvesting applications.Peer ReviewedPostprint (author's final draft

    A battery-less, self-sustaining RF energy harvesting circuit with TFETs for µW power applications

    Get PDF
    This paper proposes a Tunnel FET (TFET) power management circuit for RF energy harvesting applications. In contrast with conventional MOSFET technologies, the improved electrical characteristics of TFETs promise a better behavior in the process of rectification and conversion at ultra-low power (µW) and voltage (sub-0.25 V) levels. RF powered systems can not only benefit from TFETs in front-end rectifiers by harvesting the surrounding energy at levels where conventional technologies cannot operate but also in the minimization of energy required by the power management circuit. In this work we present an energy harvesting circuit for RF sources designed with TFETs. The TFET controller emulates an adequate impedance at the output of the rectifier in order to allow maximum transfer of power from the RF source to the input of the boost converter. The output load is activated once the output capacitor reaches a voltage value of 0.5 V. The results show an efficiency boost of 89 % for an output load consuming 1 µW with an available RF power of -25 dBm.Postprint (published version

    Reducing the loss of information through annealing text distortion

    Full text link
    Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Granados, A. ;Cebrian, M. ; Camacho, D. ; de Borja Rodriguez, F. "Reducing the Loss of Information through Annealing Text Distortion". IEEE Transactions on Knowledge and Data Engineering, vol. 23, no. 7 pp. 1090 - 1102, July 2011Compression distances have been widely used in knowledge discovery and data mining. They are parameter-free, widely applicable, and very effective in several domains. However, little has been done to interpret their results or to explain their behavior. In this paper, we take a step toward understanding compression distances by performing an experimental evaluation of the impact of several kinds of information distortion on compression-based text clustering. We show how progressively removing words in such a way that the complexity of a document is slowly reduced helps the compression-based text clustering and improves its accuracy. In fact, we show how the nondistorted text clustering can be improved by means of annealing text distortion. The experimental results shown in this paper are consistent using different data sets, and different compression algorithms belonging to the most important compression families: Lempel-Ziv, Statistical and Block-Sorting.This work was supported by the Spanish Ministry of Education and Science under TIN2010-19872 and TIN2010-19607 projects

    Kidney disease in primary anti-phospholipid antibody syndrome

    Get PDF
    APS is an autoimmune disease defined by the presence of arterial or venous thrombotic events and/or pregnancy morbidity in patients who test positive for aPL. APS can be isolated (primary APS) or associated with other autoimmune diseases. The kidney is a major target organ in APS, and renal thrombosis can occur at any level within the vasculature of the kidney (renal arteries, intrarenal vasculature and renal veins). Histological findings vary widely, including ischaemic glomeruli and thrombotic lesions without glomerular or arterial immune deposits on immunofluorescence. Renal involvement in patients with definite APS is treated with long-term anticoagulants as warfarin, but new treatments are being tried. The aim of this article is to review the links between primary APS and kidney disease

    The Antimicrobial Effects of Allium Sativum on Escherichia Coli

    Full text link
    Allium sativum (Garlic) is an herb that is grown all over the world, and can be found in the homes of many people. This herb has many medicinal properties, but is mainly known for its antimicrobial properties. Fresh garlic contains enzymes called “alliinase” and “alliin”. When garlic is crushed or cut into the alliinase converts the alliin into allicin. Allicin is what gives the garlic its antimicrobial properties and odor. The antimicrobial activity of the Allium sativum extract was tested on Escherichia coli, a gram-negative bacteria, using the agar-well diffusion method. A test tube containing only Escherichia coli was used as the control group. Another test tube containing Escherichia coli and the Allium sativum extract was used as the test group. It was hypothesized that the Allium sativum extract would prevent the growth of the Escherichia coli. With the rising costs of today’s society finding cheap and effective alternative treatments, will be helpful by providing medical help for those who can’t afford regular healthcare treatments

    An approach to the recommendation of scientific articles according to their degree of specificity

    Get PDF
    En este artículo se presenta un método para recomendar artículos científicos teniendo en cuenta su grado de generalidad o especificidad. Este enfoque se basa en la idea de que personas menos expertas en un tema preferirían leer artículos más generales para introducirse en el mismo, mientras que personas más expertas preferirían artículos más específicos. Frente a otras técnicas de recomendación que se centran en el análisis de perfiles de usuario, nuestra propuesta se basa puramente en el análisis del contenido. Presentamos dos aproximaciones para recomendar artículos basados en el modelado de tópicos (Topic Modelling). El primero de ellos se basa en la divergencia de tópicos que se dan en los documentos, mientras que el segundo se basa en la similitud que se dan entre estos tópicos. Con ambas medidas se consiguió determinar lo general o específico de un artículo para su recomendación, superando en ambos casos a un sistema de recuperación de información tradicional.This article presents a method for recommending scientific articles taking into consideration their degree of generality or specificity. This approach is based on the idea that less expert people in a specific topic prefer to read more general articles to be introduced into it, while people with more expertise prefer to read more specific articles. Compared to other recommendation techniques that focus on the analysis of user profiles, our proposal is purely based on content analysis. We present two methods for recommending articles, based on Topic Modelling. The first one is based on the divergence of topics given in the documents, while the second uses the similarities that exist between these topics. By using the proposed methods it was possible to determine the degree of specificity of an article, and the results obtained with them overcame those produced by an information retrieval traditional system.Este trabajo ha sido parcialmente financiado por los siguientes proyectos: ATTOS (TIN2012-38536-C03-03), LEGOLANG-UAGE (TIN2012-31224), FIRST (FP7-287607), DIIM2.0 (PROMETEOII/2014/001) y por el Programa Nacional de Movilidad de Recursos Humanos del Plan Nacional de I+D+i (CAS12/00113)

    La influencia de proporcionar los nombres de las cantidades en la resolución aritmética de problemas verbales

    Get PDF
    Cuando un profesor supervisa la resolución de un problema que lleva a cabo un estudiante, debe valorar el potencial de las ayudas que proporciona. Presentamos parte de una investigación que tenía como objetivo estudiar el papel de las ayudas expresadas en lenguaje natural en la resolución aritmética de problemas. En el experimento participaron 32 estudiantes de quinto curso de primaria (10-11 años). En concreto, hemos analizado cómo influye, en el proceso de resolución de un problema, el hecho de proporcionar un conjunto de nombres (o etiquetas) que hacen referencia a un número suficiente de cantidades para resolverlo. Los nombres usados eran del tipo “kilos de naranjas”, “precio de las naranjas que se han comprado”, etc. El análisis de los resultados nos ha permitido elaborar un catálogo de actuaciones en el que se reflejan los procesos de gestión y las dificultades de los estudiantes para integrar estas etiquetas en el proceso de resolución

    Analysis of the Fracture of Reinforced Concrete Flat Elements Subjected to Explosions. Experimental Procedure and Numerical Validation

    Get PDF
    Many of the material models most frequently used for the numerical simulation of the behavior of concrete when subjected to high strain rates have been originally developed for the simulation of ballistic impact. Therefore, they are plasticity-based models in which the compressive behavior is modeled in a complex way, while their tensile failure criterion is of a rather simpler nature. As concrete elements usually fail in tensión when subjected to blast loading, available concrete material models for high strain rates may not represent accurately their real behavior. In this research work an experimental program of reinforced concrete fíat elements subjected to blast load is presented. Altogether four detonation tests are conducted, in which 12 slabs of two different concrete types are subjected to the same blast load. The results of the experimental program are then used for the development and adjustment of numerical tools needed in the modeling of concrete elements subjected to blast
    corecore