Index structures for distributed text databases

The Web has became an obiquitous resource for distributed computing making it relevant to investigate new ways of providing efficient access to services available at dedicated sites. Efficiency is an ever-increasing demand which can be only satisfied with the development of parallel algorithms which are efficient in practice. This tutorial paper focuses on the design, analysis and implementation of parallel algorithms and data structures for widely-used text database applications on the Web. In particular we describe parallel algorithms for inverted files and suffix arrays structures that are suitable for implementing search engines. Algorithmic design is effected on top of the BSP model of parallel computing. This model ensures portability across diverse parallel architectures ranging from clusters to super-computers.Facultad de Informátic

Index structures for distributed text databases

The Web has became an obiquitous resource for distributed computing making it relevant to investigate new ways of providing efficient access to services available at dedicated sites. Efficiency is an ever-increasing demand which can be only satisfied with the development of parallel algorithms which are efficient in practice. This tutorial paper focuses on the design, analysis and implementation of parallel algorithms and data structures for widely-used text database applications on the Web. In particular we describe parallel algorithms for inverted files and suffix arrays structures that are suitable for implementing search engines. Algorithmic design is effected on top of the BSP model of parallel computing. This model ensures portability across diverse parallel architectures ranging from clusters to super-computers.Facultad de Informátic

Distributed search based on self-indexed compressed text

Query response times within a fraction of a second in Web search engines are feasible due to the use of indexing and caching techniques, which are devised for large text collections partitioned and replicated into a set of distributed-memory processors. This paper proposes an alternative query processing method for this setting, which is based on a combination of self-indexed compressed text and posting lists caching. We show that a text self-index (i.e., an index that compresses the text and is able to extract arbitrary parts of it) can be competitive with an inverted index if we consider the whole query process, which includes index decompression, ranking and snippet extraction time. The advantage is that within the space of the compressed document collection, one can carry out the posting lists generation, document ranking and snippet extraction. This significantly reduces the total number of processors involved in the solution of queries. Alternatively, for the same amount of hardware, the performance of the proposed strategy is better than that of the classical approach based on treating inverted indexes and corresponding documents as two separate entities in terms of processors and memory space.Fil: Arroyuelo, Diego. No especifíca;Fil: Gil Costa, Graciela Verónica. Universidad Nacional de San Luis; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: González, Senén. No especifíca;Fil: Marin, Mauricio. Universidad de Santiago de Chile; ChileFil: Oyarzún, Mauricio. Universidad de Santiago de Chile; Chil

Index structures for distributed text databases

The Web has became an obiquitous resource for distributed computing making it relevant to investigate new ways of providing efficient access to services available at dedicated sites. Efficiency is an ever-increasing demand which can be only satisfied with the development of parallel algorithms which are efficient in practice. This tutorial paper focuses on the design, analysis and implementation of parallel algorithms and data structures for widely-used text database applications on the Web. In particular we describe parallel algorithms for inverted files and suffix arrays structures that are suitable for implementing search engines. Algorithmic design is effected on top of the BSP model of parallel computing. This model ensures portability across diverse parallel architectures ranging from clusters to super-computers.Facultad de Informátic

Buckets inverted lists for a search engine with BSP

Most information in science, engineering and business has been recorded in form of text. This information can be found online in the World-Wide-Web. One of the major tools to support information access are the search engines which usually use information retrieval techniques to rank Web pages based on a simple query and an index structure like the inverted lists. The retrieval models are the basis for the algorithms that score and rank the Web pages. The focus of this presentation is to show some inverted lists alternatives, based on buckets, for an information retrieval system. The main interest is how query performance is effected by the index organization on a cluster of PCs. The server design is effected on top of the parallel computing model Bulk Synchronous Parallel-BSP.Facultad de Informátic

Bot-Based Emergency Software Applications for Natural Disaster Situations

Upon a serious emergency situation such as a natural disaster, people quickly try to call their friends and family with the software they use every day. On the other hand, people also tend to participate as a volunteer for rescue purposes. It is unlikely and impractical for these people to download and learn to use an application specially designed for aid processes. In this work, we investigate the feasibility of including bots, which provide a mechanism to get inside the software that people use daily, to develop emergency software applications designed to be used by victims and volunteers during stressful situations. In such situations, it is necessary to achieve efficiency, scalability, fault tolerance, elasticity, and mobility between data centers. We evaluate three bot-based applications. The first one, named Jayma, sends information about affected people during the natural disaster to a network of contacts. The second bot-based application, Ayni, manages and assigns tasks to volunteers. The third bot-based application named Rimay registers volunteers and manages campaigns and emergency tasks. The applications are built using common practice for distributed software architecture design. Most of the components forming the architecture are from existing public domain software, and some components are even consumed as an external service as in the case of Telegram. Moreover, the applications are executed on commodity hardware usually available from universities. We evaluate the applications to detect critical tasks, bottlenecks, and the most critical resource. Results show that Ayni and Rimay tend to saturate the CPU faster than other resources. Meanwhile, the RAM memory tends to reach the highest utilization level in the Jayma application.Fil: Ovando Leon, Gabriel. Universidad de Santiago de Chile; ChileFil: Veas Castillo, Luis. Universidad de Santiago de Chile; ChileFil: Gil Costa, Graciela Verónica. Universidad Nacional de San Luis; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Marin, Mauricio. Universidad de Santiago de Chile; Chil

A parallel search algorithm for the SAT

In order to be able to perform multimedia searches (like sounds, videos, images, etc.) we have to use data structures like the Spatial Approximation Tree (SAT). This structure is a nice example of a tree structure in which well-known tricks for tree parallelization simply do not work. It is too sparse, unbalanced and its performance is too dependent on the work-load generated by the queries being solved by means of searching the tree. The complexity measure is given by the number of distances computed to retrieve those objects close enough to the query. In this paper we examine some alternatives to parallelize this structure through the MPI library and the BSPpub library.Facultad de Informátic

Evaluacion de dosis y tiempo de aplicacion de nuevos fungicidas sobre el control de Venturia inaequalis y Podosphaera leucotricha en manzano.

Resumen (Spanish, English)51 p.Las dos más importantes enfermedades del manzano, tanto en Chile como en las distintas zonas productoras del mundo, son venturia y oidio, causadas por los hongos Venturia inaequalis y Podosphaera leucotricha respectivamente. En los últimos años se han comenzado a utilizar fungicidas que presentan efecto retroactivo o erradicante sobre ambas enfermedades ya que permiten retrasar las aplicaciones, aún después de presentadas las condiciones de temperatura y humedad para el desarrollo de estas enfermedades, lo que se traduce finalmente en ahorro de recursos. En 1996 en la Comuna de Río Claro, VII Región, a 3 km al oeste de la localidad de Cumpeo (35º16’ latitud sur, 71º15’ longitud oeste) se realizaron ensayos sobre hojas y frutos de manzanos cultivar Starkimson para determinar la dosis óptima y tiempo óptimo de aplicación post infección de los fungicidas kresoxim metil (grupo de las estrobirulinas) y tebuconazole (fungicida IBE), en el control de Venturia inaequalis en manzano, mediante mediciones de incidencia y severidad de la enfermedad. Por otra parte, el mismo año en la Estación Experimental Panguilemo de la Universidad de Talca, ubicada a 4 Km al norte de esta ciudad a un costado de la carretera panamericana, 35º25’ latitud sur, 71º37’ longitud oeste, se realizaron ensayos sobre hojas y frutos de manzano de la variedad Royal Gala para establecer la dosis óptima de tebuconazole para el control de Podosphaera leucotricha en manzano y para determinar el fungicida más efectivo entre tebuconazole y miclobutanil en el control de esta enfermedad, también midiendo incidencia y severidad. El fenómeno de la Niña se presentó el año de estudio arrojando una alta sequía con un déficit de precipitaciones de 46,8% y sólo dos períodos infectivos para Venturia inaequalis en contraste con los 7 a 10 que se registran en una temporada normal (Latorre, 1992). Esta situación no permitió determinar la eficiencia ni la retroactividad de los fungicidas Kresoxim metil y Tebuconazole en el control de Venturia inaequalis, sin embargo, se determinó que para estas condiciones, Tebuconazole presentó un efecto retroactivo en el control de la enfermedad de 72 horas en hojas de manzano, no determinándose su retroactividad en frutos. Respecto a Podosphaera leucotricha, tampoco fue posible determinar la eficiencia ni la retroactividad de los fungicidas Tebuconazole y Miclobutanil en su control, debido principalmente a las condiciones climáticas de la temporada de estudio, que se tradujeron en una muy baja incidencia de esta enfermedad. En un año de sequía alta o severa, la incidencia de venturia y oidio en manzano es muy baja, alcanzando niveles de infección de promedio en hojas y frutos de sólo 3,2% para la primera enfermedad y 8,0% para la segunda. Se recomienda repetir los ensayos en años de condiciones climáticas normales, especialmente respecto a precipitaciones, de forma tal de contar con una incidencia que permita detectar diferencias en la eficacia de los fungicidas estudiados

Implementación de un modelo de análisis de dispersión atmosférica de material particulado (PM10) a través de la herramienta AERMOD VIEW en el municipio de Yumbo (Valle del Cauca).

Anexos (Glosario, características modelo Aermod View, Listado de las empresas y RAE)Trabajo aplicado de modelación de dispersión de material particulado menor a diez micrometros en la zona industrial del municipio de Yumbo, debido a los altos niveles reportado e la estación de calidad del aire denominada El País y operada por la CVC en el marco de sus competencias, verificando la dispersión de PM10 en el trabajó se observó que existen mayores aportes y concentraciones en el sector Canteras del municipio y que la dispersión de PM10 se da debido a la dirección y velocidad de los vientos de la zona, evitando la deposición de estos en receptores sensibles como la población del casco urbano de Cali y Yumbo.Applied work of modeling dispersion of particulate material less than ten micrometers in the industrial area of ​​the municipality of Yumbo, due to the high levels reported in the air quality station called El País and operated by the CVC within the framework of its competences, Verifying the dispersion of PM10 in the work, it was observed that there are greater contributions and concentrations in the Canteras sector of the municipality and that the dispersion of PM10 occurs due to the direction and speed of the winds in the area, avoiding the deposition of these in receivers. sensitive as the population of the urban area of ​​Cali and Yumbo