OLAP4Tweets: Multidimensional Modeling of tweets

International audienceTwitter, a popular microblogging platform, is at the epicenter of the social media explosion, with millions of users being able to create and publish short posts, referred to as tweets, in real time. The application of the OLAP (On-Line Analytical Processing) on large volumes of tweets is a challenge that would allow the extraction of information (especially knowledge) such as user behavior, new emerging issues, trends… In this paper, we pursue a goal of providing a generic multidimensional model dedicated to the OLAP of tweets. The proposed model reflects on some specifics such as recursive references between tweets and calculated attributes

Implementation of the Multidimensional Modeling Concepts into Object-Relational Databases

A key to survival in the business world is being able to analyze, plan and react to changing business conditions as fast as possible. With multidimensional models the managers can explore information at different levels of granularity and the decision makers at all levels can quickly respond to changes in the business climate-the ultimate goal of business intelligence. This paper focuses on the implementation of the multidimensional concepts into object-relational databases.e-business, database

Multidimensional Modeling of Atmospheric Effects and Surface Heterogeneities on Remote Sensing

The overall goal of this project is to establish a modeling capability that allows a quantitative determination of atmospheric effects on remote sensing including the effects of surface heterogeneities. This includes an improved understanding of aerosol and haze effects in connection with structural, angular, and spatial surface heterogeneities. One important objective of the research is the possible identification of intrinsic surface or canopy characteristics that might be invariant to atmospheric perturbations so that they could be used for scene identification. Conversely, an equally important objective is to find a correction algorithm for atmospheric effects in satellite-sensed surface reflectances. The technical approach is centered around a systematic model and code development effort based on existing, highly advanced computer codes that were originally developed for nuclear radiation shielding applications. Computational techniques for the numerical solution of the radiative transfer equation are adapted on the basis of the discrete-ordinates finite-element method which proved highly successful for one and two-dimensional radiative transfer problems with fully resolved angular representation of the radiation field

Three-dimensional Continuum Radiative Transfer Images of a Molecular Cloud Core Evolution

We analyze a three-dimensional smoothed particle hydrodynamics simulation of an evolving and later collapsing pre-stellar core. Using a three-dimensional continuum radiative transfer program, we generate images at 7 micron, 15 micron, 175 micron, and 1.3 mm for different evolutionary times and viewing angles. We discuss the observability of the properties of pre-stellar cores for the different wavelengths. For examples of non-symmetric fragments, it is shown that, misleadingly, the density profiles derived from a one-dimensional analysis of the corresponding images are consistent with one-dimensional core evolution models. We conclude that one-dimensional modeling based on column density interpretation of images does not produce reliable structural information and that multidimensional modeling is required.Comment: accepted by ApJL, 4 pages, 4 figure

Extending Uml for Multidimensional Modeling in Data Warehouse

Multidimensional modeling is the foundation of data warehouses, MD databases, and On-Line Analytical Processing (OLAP) applications. Nowadays Dimensional modeling and object-orientation are becoming growing interest areas. In the past few years; there have been many proposals, for representing the MD properties at the conceptual level. However, none of them has been accepted as a standard for conceptual MD modeling. In this paper, we present an extension of the Unified Modeling Language (UML) using a UML profile for multidimensional databases. This profile is composed of a set of stereotypes, constraints and tagged values. We have extended the uml for representing the main multidimensional properties at the conceptual level such as the many-to-many relationships between facts and dimensions, degenerate dimensions, multiple and alternative path classification hierarchies, and nonstrict and complete hierarchies and aggregate fact table

Using Ontologies for the Design of Data Warehouses

Obtaining an implementation of a data warehouse is a complex task that forces designers to acquire wide knowledge of the domain, thus requiring a high level of expertise and becoming it a prone-to-fail task. Based on our experience, we have detected a set of situations we have faced up with in real-world projects in which we believe that the use of ontologies will improve several aspects of the design of data warehouses. The aim of this article is to describe several shortcomings of current data warehouse design approaches and discuss the benefit of using ontologies to overcome them. This work is a starting point for discussing the convenience of using ontologies in data warehouse design.Comment: 15 pages, 2 figure

On the Need for Multidimensional Stirling Simulations

Given the cost and complication of simulating Stirling convertors, do we really need multidimensional modeling when one-dimensional capabilities exist? This paper provides a comprehensive description of when and why multidimensional simulation is needed