Presentaciones a Congresos
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- Ponencia en CongresoSynthesis of LEB (Linear-ellipsoidal-bounded) regulators and filters for discrete-time systems(1987) Antonini, Claudio Daniel"This work is applicable to LTI systems, described by state-variables, whose measurement errors, controls and outputs are to be bounded by upper and lower measurement noises and bounded disturbances. The methodology has been named LEB for its apllication to linear systems, whose variables are contained within Ellipsoidal sets when disturbances and noises are bounded."
- Ponencia en CongresoDevelopment of an optimized LEB filter and its application to INS/GPS test data(1993) Antonini, Claudio Daniel"An optimized linear-ellipsoidal-bounded (LEB) filter has been developed and applied to data obtained from a ground test using a combined INS/GPS configuration. In this cascaded configuration, the filter receives eight outputs from the INS (accelerations, velocity, angles, altitude) and six outputs from the GPS (velocities and positions). The GPS measurements have included the effect of selected availability (SA)-of varying or unknown spectrum-which, although likely to be estimated and compensated with some modelling techniques-at the expense of including extra state variables-could also be dealt with using the approach indicated in this article with much less effort. The SA effect is modelled as an unknown-but-bounded (UBB) noise process. Comparisons with an extended Kalman filter (KF) show that KF innovations are not white and the LEB filter innovations are one order of magnitude smaller than those produced by the KF. A simple second order example is developed to show the behavior of the LEB filter when compared to a KF."
- Ponencia en CongresoDiscounting rate: a matter of common sense rather than a theoretical problem(1999) Rosbaco, Juan“Different rates proposed by several authors to discount cashflows of given projects are discussed. The paper starts by reviewing what the objectives of an evaluation are and later presents the different discount rates suggested by the authors. After a theoretical but fundamentally logical analysis it is concluded that there is no universal discount rate that can be used in all situations; to do so would disregard both the fact that an evaluation can have different objectives and that the environment in which projects will be carried out and companies will develop is unique in each case.”
- Ponencia en CongresoMultiple internal rates of return: when to anticipate multiple IRRs and how to take advantage of them to perform a better evaluation(1999) Rosbaco, Juan“There are different rules to delimit or exactly determine the number of Internal Rates of Return a project may have or has. These rules show that, when the sequence of signs of the cumulative cash flow vs time function is the normal one - negative figures at the start and then only positive ones – there is only one Internal Rate of Return. There are few projects in which there are multiple intersections of cumulative cash flow with the time axis : a number of acceleration projects, complex financing investments, and a few other serial projects. However, not all of them have multiple Internal Rates of Return. The discussion presented in this paper addresses the question of how to empirically infer the existence of multiple rates, and how to use them for the benefit of the evaluation. Moreover, it demonstrates that all multiple rates have the same physical meaning, which does not vary with respect to the traditional single rate case.”
- Ponencia en CongresoInfluence of temperature and interfacial tension on spontaneous imbibition process(1999-01) Chimienti, M. E.; Illiano, S. N.; Najurieta, H. L.“Spontaneous imbibition is a mechanism that can significantly contribute to the production rate and final oil recovery in fractured and stratified reservoirs. This mechanism is affected by rock and fluid properties and it has been reported by several authors to be strongly dependent on interfacial tension (IFT) and contact angle. Both magnitudes are influenced by system temperature. In this work a laboratory study is performed on the influence of IFT and temperature on production rate and oil recovery for a given rock-fluid system. All sequences were performed on rock and fluid samples from Argentine basins. Rock samples were of medium permeability (56.1 to 83.1 mD) and porosity ranging from 18.7 % to 22.9 %. The fluids used were formation water and medium viscosity oil (45 cp at standard conditions). The samples were carried to irreducible water saturation before performing the imbibition tests resembling the assumed reservoir condition. Initial tests were designed including representative water, oil and rock samples at several temperature levels. Another sequence of tests were performed with the addition of variable amounts of water dispersed surfactant. A noticeable influence of experimental conditions was found on the final results. As part of the tests, the same final temperature was reached through single and several steps observing the differences in overall performance.”
- Ponencia en CongresoLearning by knowledge sharing in autonomous intelligent systems(2006) García Martínez, Ramón; Borrajo, Daniel; Maceri, Pablo; Britos, Paola Verónica"Very few learning systems applied to problem solving have focused on learning operator definitions from the interaction with a completely unknown environment. In order to achieve better learning convergence, several agents that learn separately are allowed to interchange each learned set of planning operators. Learning is achieved by establishing plans, executing those plans in the environment, analyzing the results of the execution, and combining new evidence with prior evidence. Operators are generated incrementally by combining rote learning, induction, and a variant of reinforcement learning. The results show how allowing the communication among individual learning (and planning) agents provides a much better percentage of successful plans, plus an improved convergence rate than the individual agents alone."
- Ponencia en CongresoThe power of dispersion management for 10-Gb/s and 40-Gb/s systems(2006) Grosz, Diego; Agarwal, A.; Küng, A. P.; Maywar, D. N.; Lakoba, T. I."We review applications and requirements of dispersion compensation that enable highcapacity, long-haul, and ultra-long-haul 10-Gb/s and 40-Gb/s DWDM transmission. We briefly describe their impact on system performance and present sorne future perspectives."
- Ponencia en CongresoIdentification of velocity variations in a seismic cube using neural networks(2006) Cersósimo, Darío Sergio; Ravazoli, Claudia; García Martínez, Ramón"This research allow to infer that from seismic section and well data it is possible to determine velocity anomalies variations in layers with thicknesses below to the seismic resolution using neuronal networks."
- Ponencia en CongresoPatterns in temporal series of meteorological variables using SOM & TDIDT(2006) Cogliati, Marisa; Britos, Paola Verónica; García Martínez, Ramón"The purpose of the present article is to investigate if there exist any such set of temporal stable patterns in temporal series of meteorological variables studying series of air temperature, wind speed and direction an atmospheric pressure in a period with meteorological conditions involving nocturnal inversion of air temperature in Allen, Rio Negro, Argentina. Our conjecture is that there exist independent stable temporal activities, the mixture of which give rise to the weather variables; and these stable activities could be extracted by Self Organized Maps plus Top Down Induction Decision Trees analysis of the data arising from the weather patterns, viewing them as temporal signals."
- Ponencia en CongresoPrediction in health domain using Bayesian networks optimization based on induction learning techniques(2006) Felgaer, Pablo; Britos, Paola Verónica; García Martínez, Ramón"A Bayesian network is a directed acyclic graph in which each node represents a variable and each arc a probabilistic dependency; they are used to provide: a compact form to represent the knowledge and exible methods of reasoning. Obtaining it from data is a learning process that is divided in two steps: structural learning and parametric learning. In this paper we define an automatic learning method that optimizes the Bayesian networks applied to classification, using a hybrid method of learning that combines the advantages of the induction techniques of the decision trees (TDIDT-C4.5) with those of the Bayesian networks. The resulting method is applied to prediction in health domain."
- Ponencia en CongresoConceptualization maturity metrics for expert systems(2006) Britos, Paola Verónica; García Martínez, Ramón; Hauge, Ødwin“Metrics used on development of expert systems is not a well investigated problem area. This article suggests some metrics to be used to measure the maturity of the conceptualization process and the complexity of the decision process in the problem domain. We propose some further work to be done with these metrics. Applying those metrics makes new and interesting problems, concerning the structure of knowledge to surface.”
- Ponencia en CongresoDetection of breast lesions in medical digital imaging using neural networks(2006) Ferrero, Gustavo; Britos, Paola Verónica; García Martínez, Ramón"The purpose of this article is to present an experimental application for the detection of possible breast lesions by means of neural networks in medical digital imaging. This application broadens the scope of research into the creation of different types of topologies with the aim of improving existing networks and creating new architectures which allow for improved detection."
- Ponencia en CongresoReal time stable identification: A Nehari/SOS approach(2007) García Galiñanes, Rafael; Sánchez-Peña, Ricardo; Mancilla-Aguilar, J. L."Here we present an adaptive identification algorithm based on Second Order section (SOS) model structures. The procedure guarantees stable transfer functions whenever the actual physical plant is stable, due to an optimal Nehari approximation step performed analytically. The procedure is suitable to be implemented in real time applications. Some examples illustrate the proposed algorithm."
- Ponencia en CongresoRequirements elicitation in data mining for business intelligence projects(2008) Britos, Paola Verónica; Dieste, Oscar; García Martínez, Ramón"There are data mining methodologies for business intelligence (DM-BI) projects that highlight the importance of planning an ordered, documented, consistent and traceable requirement’s elicitation throughout the entire project. However, the classical software engineering approach is not completely suitable for DM-BI projects because it neglects the requirements specification aspects of projects. This article focuses on identifying concepts for understand DM-BI project domain from DM-BI field experience, including how requirements can be educed by a proposed DM-BI project requirements elicitation process and how they can be documented by a template set."
- Ponencia en CongresoPedagogical protocols selection automatic assistance(2008) Britos, Paola Verónica; Cataldi, Zulma; Sierra, Enrique; García Martínez, Ramón"The preliminary results presented in this paper corresponds to a research project oriented to the search of the relationship between the predilection of students concerning learning style and the pedagogical protocols used by the human tutors (professors during the first courses of the Computer Engineering undergraduate Program) by using intelligent systems tools."
- Ponencia en CongresoWork in progress: programming misunderstandings discovering process based on intelligent data mining tools(2008) Britos, Paola Verónica; Jiménez Rey, Elizabeth; Rodríguez, Darío; García Martínez, Ramón"We present research work in progress that focuses on data mining tools used for helping teachers to apply a three step knowledge discovering process to diagnose students’ misunderstandings (and their causes) related to their programming errors."
- Ponencia en CongresoRE-SPaM: Using regular expressions for sequential pattern mining in trajectory databases(2008) Gómez, Leticia Irene; Vaisman, Alejandro Ariel"In sequential pattern mining, languages based on regular expressions (RE) were proposed to restrict frequent sequences to the ones that satisfy user-specified constraints. In these languages, REs are applied over items. We propose a much powerful language, based on regular expressions, denoted RE-SPaM, where the basic elements are constraints over the attributes of the items. Expressions in this language may include attributes, functions over attributes, and variables. We present the data model, sketch the syntax and semantics of RE-SPaM, a set of examples, and suggest how RE-SPaM can be used in the mining process."
- Ponencia en CongresoLearning life cycle in autonomous intelligent systems(2008) Ierache, Jorge; García Martínez, Ramón; De Giusti, Armando"Autonomous Intelligent Systems (AIS) integrate planning, learning, and execution in a closed loop, showing an autonomous intelligent behavior. A Learning Life Cycle (LLC) Operators, Trained Base Operators and World Interaction Operators. The extension of the original architecture to support the new type of operators is presented."
- Ponencia en CongresoOptimizing relationships information in repertory grids(2008) Calot, Enrique; Britos, Paola Verónica; García Martínez, Ramón"The Repertory Grid method is widely used in knowledge engineering to infer functional relationships between constructs given by an expert. The method is ignoring information that could be used to infer more precise dependencies. This paper proposes an improvement to take advantage on the information that is being ignored in the current method. Furthermore, this improvement fixes several other limitations attached to the original method, such as election in a discrete set of two values as a similarity pole or a contrast pole, the arbitrary measurement of distances, the unit-scale dependency and the normalization, among others. The idea is to use linear regression to estimate the correlation between constructs and use the fitness error as a distance measure."
- Ponencia en CongresoAggregation languages for moving object and places of interest(2008) Gómez, Leticia Irene; Kuijpers, Bart; Vaisman, Alejandro Ariel"We address aggregate queries over GIS data and moving object data, where non-spatial information is stored in a data warehouse. We propose a formal data model and query language to express complex aggregate queries. Next, we study the compression of trajectory data, produced by moving objects, using the notions of stops and moves. We show that stops and moves are expressible in our query language and we consider a fragment of this language, consisting of regular expressions to talk about temporally ordered sequences of stops and moves. This fragment can be used not only for querying, but also for expressing data mining and pattern matching tasks over trajectory data."