Dr. Roberto Therón Departamento de Informática y Automática Facultad de Ciencias Universidad de Salamanca Plaza de la Merced S/N 37008, Salamanca Spain
Roberto Therón received his doctoral degree from the Robotics Group at the Univerisidad de Salamanca, where his research focused on combining fields such as Computer Science, Artificial Intelligence, Statistics, Graphic Design, and Data Visualization as a means for understanding complex data. After completing his thesis, he spent time developing tools for the visualization of multidimensional data such as genetic or paeloclimatic data.
Currently is the Group manager of the Visual Analytics and Information Visualization Research Group (VisUsal), devoted to the development of advanced tools that help users in understanding complex datasets coming from a variety of fields...
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The following is just a list of selected publications (if you would like to have a look of a complete list of publicationss you can check it here).
Abstract: Usability is generally regarded as ensuring that software products are effective and efficient to use from the userâs perspective. Diverse aspects that ensure the usability of a software product should be assessed during the different phases in its life cycle. The goal of usability testing is to evaluate whether or not a tool that is being developed will be usable by the end user in order to achieve the tasks for which it is being designed. This paper is targeted at describing the evaluation and the usability of OWL-VisMod, a visual modelling tool for OWL ontologies, from the point of view of the human-computer interaction. This evaluation is based on a user-centred approach and the use of questionnaires. The whole usability evaluation process is described and the results are discussed.
Abstract: Hypergraphs drawn in the subset standard are useful to represent group relationships using topographic characteristics such as intersection, exclusion and enclosing. However, they present cluttering when dealing with a moderately high number of nodes (more than 20) and large hyperedges (connecting more than 10 nodes, with three or more overlapping nodes). At this complexity level, a study of the visual encoding of hypergraphs is required in order to reduce cluttering and increase the understanding of larger sets. Here we present a graph model and a visual design that help in the visualization of group relationships represented by hypergraphs. This is done by the use of superimposed visualization layers with different abstraction levels and the help of interaction and navigation through the display.
Abstract: Many online communities use TagClouds, an aesthetic and easy to understand visualization, to represent popular tags collaboratively generated by their users. However, due to the free nature of tagging, such collaborative tags have linguistic problems and limitations, such as high semantic density. Moreover, the alphabetical order of TagClouds poorly supports a hierarchical exploration among tags. This paper presents an exploration to support semantic understanding of collaborative tags beyond TagClouds. Based on the results of the authorsâ survey of practical usages of collaborative tags, they developed a visualization named TagClusters, in which tags are clustered into different groups, with font size representing tag popularity and the spatial distance indicating the semantic similarity between tags. The subgroups in each group and the overlap between groups are highlighted, illustrating the underlying hierarchical structure and semantic relations between groups. The authors conducted a comparative evaluation with TagClouds and TagClusters based on the same tag set. The results confirmed the advantage of TagClusters in facilitating browsing, comparing and comprehending semantic relations between tags.
Abstract: This paper addresses the problem of visualizing video search results in YouTube [36] from three perspectives: (1) The adaptation of a visualization technique for give an overview of recovered videos and help the user to recognize relationships, patterns and trends among videos; (2) Using a graph-based technique for exploratory video search using the relations among labels and other related videos; (3) The implementation of video preview techniques, to provide information on their visual content. As a research proposal was implemented ViRe-YouTube, a system to video search that replaces the traditional interaction (in which the user submits a query and the system displays a list of results) with a interaction style similar to exploration, in which the organization and presentation of results help users to understand the set of videos retrieved and help users to make a better selection of videos to playback.
Abstract: SUMMARY: Treevolution is a tool for the representation and exploration of phylogenetic trees that facilitates visual analysis. There are several useful tools to visualize phylogenetic trees, but their level of interaction is usually low, especially in the case of radial representations. Highly interactive visualizations can improve the exploration and understanding of phylogenetic trees. Treevolution implements strategies to interact with phylogenetic trees in order to allow a more thorough analysis by users. AVAILABILITY: Treevolution is available at http://vis.usal.es/treevolution. Additional figures, a user's guide, a video demo and some examples are available at the same site. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.
Abstract: The quality of Learning Objects (LOs) is currently being promoted by certain tools which consider specific criteria for their evaluation; however, there is no existing methodology that considers both the value assigned to the LO itself and the percentage related to the number of evaluators who have compared the quality of resources. As in the case of various products offered through the Internet backed by an assessment of users in a unified ranking, the purpose of this paper is to suggest a proposal for the automated assessments of experts who can clearly see the best or worst aspects in LO quality.
Abstract: This article presents Semantic Spiral Timelines (SST) as an interactive visual tool aimed at the exploration and analysis of additional academic information stored in current e-learning platforms. Despite the development of contents specifically for these platforms, and in spite of the various features they provide, knowledge of the actual use made by individual participants is emerging as an unavoidable necessity, so as to ensure proper operation and effective use of e-learning platforms. SST supports the discovery of temporal patterns by incorporating an innovative highly interactive visual representation, which can be explored at various levels. This tool makes it possible to assess, at first glance, the use of the e-learning platform during the development of courses; one can also perceive how it is used by class participants. Then, through different interaction mechanisms, it is possible for students and professors to uncover specific details about courses, which would otherwise remain hidden.
Abstract: BACKGROUND: Microarray analysis is an important area of bioinformatics. In the last few years, biclustering has become one of the most popular methods for classifying data from microarrays. Although biclustering can be used in any kind of classification problem, nowadays it is mostly used for microarray data classification. A large number of biclustering algorithms have been developed over the years, however little effort has been devoted to the representation of the results. RESULTS: We present an interactive framework that helps to infer differences or similarities between biclustering results, to unravel trends and to highlight robust groupings of genes and conditions. These linked representations of biclusters can complement biological analysis and reduce the time spent by specialists on interpreting the results. Within the framework, besides other standard representations, a visualization technique is presented which is based on a force-directed graph where biclusters are represented as flexible overlapped groups of genes and conditions. This microarray analysis framework (BicOverlapper), is available at http://vis.usal.es/bicoverlapper CONCLUSION: The main visualization technique, tested with different biclustering results on a real dataset, allows researchers to extract interesting features of the biclustering results, especially the highlighting of overlapping zones that usually represent robust groups of genes and/or conditions. The visual analytics methodology will permit biology experts to study biclustering results without inspecting an overwhelming number of biclusters individually.
Abstract: BicOverlapper is a tool to visualize biclusters from gene-expression matrices in a way that helps to compare biclustering methods, to unravel trends and to highlight relevant genes and conditions. A visual approach can complement biological and statistical analysis and reduce the time spent by specialists interpreting the results of biclustering algorithms. The technique is based on a force-directed graph where biclusters are represented as flexible overlapped groups of genes and conditions. AVAILABILITY: The BicOverlapper software and supplementary material are available at http://vis.usal.es/bicoverlapper
Abstract: MOTIVATION: Although natural products represent a reservoir of molecular diversity, the process of isolating and identifying active compounds is a bottleneck in drug discovery programs. The rapid isolation and identification of the bioactive component(s) of natural product mixtures during the bioassay-guided fractionation have become crucial factors in the competition with chemical compound libraries and combinatorial synthetic efforts. In this respect, the use of spectral databases in identification processes is indispensable. RESULTS: We have developed a database containing (13)C spectral information of over 6000 natural compounds, which allows for fast identifications of known compounds present in the crude extracts and provides insight into the structural elucidation of unknown compounds. AVAILABILITY: http://c13.usal.es
Abstract: As a symptom of evolution, human beings are always trying to better understand current and past events so as to be able to foresee future situations. In order to do that the development of new tools and/or methods is a must. Currently, the Modern Analog Technique (MAT) is one of the most used techniques in paleoceanography and it is applied for the quantitative reconstruction of environmental conditions of the past. Here we propose a new tool, PaleoAnalogs, a method that combines the MAT technique with an interactive analysis to produce faster and more accurate down core reconstructions of (i.e.) sea surface temperature. The tool is tested here using planktonic foraminifers from Pleistocene sediments in the Mediterranean sea, where a well-build database is available. PaleoAnalogs is programmed with flexibility in order to enable the use of this technique for different micropaleontological groups and it is available for any operating system.
Abstract: In this paper it is presented the assesment of two different methods devoted to the evaluation of the configuration space for planar revolute manipulators. The formalism proposed in [3] for the evaluation of the C-space, when applied to planar revolute manipulators, is compared to a new method, which provides both better results and a way to generalize the evaluation for any kind of robotic structure.
Abstract: Large Software Projects need to be represented in a conceptual way for humans to understand. Nevertheless, most of the time the diagrams involved are far from clear and understandable. The use of advanced visualization techniques is useful for large projects and representations in order to clarify the abstraction process. This paper proposes the use of well known visualization techniques to enrich UML models in the structural and hierarchical representation of these types of projects. A first prototype has been developed to test the proposal and the results are described below.
Abstract: The use of visual representations and interaction techniques to provide faster insight into
complex data is what distinguishes visual analytics from other types of visualization tools.
Visual representations translate data into visible forms that highlight important features,
including commonalities and anomalies. These visual representations help users to quickly
perceive salient aspects of their data. Augmenting the cognitive reasoning process with
perceptual reasoning through visual representations permits the analytical reasoning
process to become faster and more focused. Visual Analytics is an emerging area of research
and practice that aims to support analytical reasoning through interactive visual interfaces.
This chapter discusses important aspects involved in proposing and developing novel
interactive visual tool solutions. Those tools can help users of Learning Content
Management Systems (LCMS), or Learning Management Systems (LMS) to extract specific
knowledge of academic and non-academic information stored in current e-learning
platforms. It covers three primary topics. First, it focuses on the psycho-pedagogical theory
that justifies the design and use of this software. Next, it addresses the visual
representations and interaction techniques and related works that support e-learning.
Finally, it considers possible future work and conclusions.
Abstract: This book is the result of a community effort of the partners of the VisMaster Coordinated Action funded by the European Union. The overarching aim of VisMaster was to create a research roadmap that outlines the current state of visual analytics across many disciplines, and to describe the next steps that have to be taken to foster a strong visual analytics community, thus enabling the development of advanced visual analytic applications.
This chapter considers data mining, which is seen as fundamental to the automated analysis components of visual analytics. Since todayâs datasets are often extremely large and complex, the combination of human and automatic analysis is key to solving many information gathering tasks. Some case studies are presented which illustrate the use of knowledge discovery and data mining (KDD) in bioinformatics and climate change. The authors then pose the question of whether industry is ready for visual analytics, citing examples of the pharmaceutical, software and marketing industries. The state of the art section gives a comprehensive review of data mining/analysis tools such as statistical and mathematical tools, visual data mining tools, Web tools and packages. Some current data mining/visual analytics approaches are then described with examples from the bioinformatics and graph visualisation fields. Technical challenges specific to data mining are described such as achieving data cleaning, integration, data fusion etc. in real-time and providing the necessary infrastructure to support data mining. The challenge of integrating the human into the data process to go towards a visual analytics approach is discussed together with issues regarding its evaluation. Several opportunities are then identified, such as the need for generic tools and methods, visualisation of models and collaboration between the KDD and visualisation communities.
Abstract: Visual Analytics require the use of large datasets and most of the time visualizations use their own data structures definition or make use of simple standards such as XML, CVS, or text files. Our proposal presents a middleware framework that focuses on providing a way to manage those data structures, allowing to access heterogeneous data sources. The framework allows defining data structures for different visualizations using the same dataset. It dynamically generates a visual interface that allows users to define data structures according to the specific visualization requirements. It also provides a repository to store data structures to reuse them in other visualizations or by means of inheritance, composition and associations. We have implemented a first prototype, which is discussed in the results presented on this paper.
Abstract: Virtual screening (VS) experiments yield huge numbers of configurations (conformations plus rotations plus translations). In order to extract important structural information from such a complex database, new chemoinformatic tools are urgently needed. We have clustered and classified by means of âad hocâ semiautomatic chemoinformatic tools the poses arising from docking experiments conducted on more than 700,000 compounds on tubulin. The results obtained in this way have been compared with those achieved by visual inspection protocols in an attempt to develop new useful tools.
Abstract: This paper describes the characteristics and the improvements of the free web-based spectral database NATPRO-C13, containing C-13 NMR spectra data from more than 5.000 natural compounds and related derivates. It provides tools that facilitate the structural identification of natural compounds even before their purification. This database allows for searches by chemical structure, substructure, name, family compounds, and by spectral features i.e. chemical shifts and multiplicities. These capabilities are used together with visual interactive tools, which enable the structural elucidation of known and unknown compounds by comparison of their C-13 NMR data.
Abstract: The literature in educational research has
established that monitoring student learning is a crucial
component of high quality education. When instructors and
students are not in a face-to-face traditional environment, new
forms of student monitoring must be explored. The effective
use of CMS requires that instructors been provided with
appropriate means of diagnosing problems so that they can
take immediate actions to prevent or overcome those
situations. The aim of this research is to support the
comprehension of the evolution of the semantic content within
eLearning environments through uncovering by means of
visual representations. Therefore, we have carried out the
mining of an eLearning database and represented the more
relevant results by depicting them using a visualization based
in the tag cloud visual representation. In this paper, we
introduce a visual representation, which integrate a wavegraph
and a bar-graph into a tag cloud representation to
understand the evolution of words
Abstract: In the context of the Web, an ontology provides a shared
insight of a certain domain. Ontologies are represented with a set of
classes and diverse relationships among them. Visual modeling is used
to represent the structure, relations among classes and instances. The
current visual models to represent ontologies are mainly based on the
use of UML, and in a minor way MOF and OCL. In this article we
propose a framework to visually analyze and modeling ontologies from
a different point of view by combining different visualization techniques
to enrich the modeling process. We tested our framework with some
ontologies publicly available and the results are discussed
Abstract: This paper aims to propose some new metrics to measure
relationships among classes in an ontology. Relationships among classes
in an OWL ontology are given by the object properties that are defined as
a binary relation between classes in the domain with classes in the range.
Our proposal is based on the coupling metric defined in the software
engineering field adapted to an ontology needs. We have implemented
and tested our metrics with real ontologies and the results are analysed
and discussed.
Abstract: This work aims to facilitate the task of basketball coaches, by means
of the visualization and analysis of the playersâ movements in the court. This
is possible thanks to the use of Global Positioning System (GPS) devices that
generate data of the position of the player, almost in real time. The main objective
of our proposal consists on the tracking, both statistics and kinematics, of a
basketball player due to the physical activity developed during a match. The comparison
of the data from several players or between two teams also will improve
the performance and tactical capacity of players and trainers.
On one hand, the study of time-motion in sports is largely covered in the literature.
On the other hand, the use of personal GPS devices for training purposes
is a common practice. However, the design of interactive visualization tools that
exploit the data stored in GPS devices during a match, thus enabling to perform
its visual analysis, is still an open area. The work presented in this paper identifies
the relevant aspects of the basketball game that are valuable for a coach in terms
of team and individual performance analysis, and discusses the design and implementation
of a tool that exploits the methods and techniques of a visual analytics
approach.
Abstract: Despite the development of contents specifically for LMS, and in spite of the various features they provide, knowledge of the actual use made by individual participants is emerging as a unavoidable necessity, so as to ensure proper operation and effective use of LMS. Moreover, the use of highly interactive visual tools can provide the benefit of understanding the educational process recorded in the database associated with the current platforms. However, there exists the problem of the integration, or not, with the LMS and therefore the transparent retrieval information and usage of these tools for the students as well as tutors
Abstract: Despite the development of contents specifically for LMS, and in spite of the various features they provide, the knowledge of the actual use made by individual participants is emerging as a unavoidable necessity, so as to ensure proper operation and effective use of LMS. Moreover, the use of highly interactive visual tools can provide the benefit of understanding the educational process recorded in the database associated with the current platforms. However, there exists the problem of the integration, or not, with the LMS and therefore the transparent retrieval information and usage of these tools for the students as well as tutors.
Abstract: This paper aims to support the software development and maintenance process with the assistance of a visual analytics tool proposal. The proposal focuses on providing detailed information about the software project structure, class relationships, class coupling, class level metrics and source code. It discloses project structure details and offers interaction techniques in order to quickly review source code classes and obtain insight of their relationships and coupling. The data used in the analysis and visualization has been extracted from Software Configuration Management (SCM) tool repositories. Finally, a case study and the results of applying our tool to several software project revisions are discussed.
Abstract: Drug design is very complex and expensive. Finding new active chemical structures is a very important goal. Both experimental and virtual (in silico) screenings can be used to explore chemical space [11][12]. With virtual screening it is possible to reduce the amount of compounds for experimental evaluations. Moreover, when the 3D structure of the target is known, candidate molecules can be put to fit in the target hole in different positions and later cluster these positions in order to find the best to fit. Therefore, we propose a visual tool that couples with Jmol[21] viewer, provides together with a means of visually exploring clustered molecules, an overview of the majority of the data, supporting thus the decision making in the process of new drugs design.
Abstract: TagClouds is a popular visualization for the collaborative tags. However it has some instinct problems such as linguistic issues, high semantic density and poor understanding of hierarchical structure and semantic relation between tags. In this paper we investigate the ways to support semantic understanding of collaborative tags and propose an improved visualization named TagClusters. Based on the semantic analysis of the collaborative tags in Last.fm, the semantic similar tags are clustered into different groups and the visual distance represents the semantic similarity between tags, and thus the visualization offers a better semantic understanding of collaborative tags. A comparative evaluation is conducted with TagClouds and TagClusters based on the same tags collection. The results indicate that TagClusters has advantages in supporting efficient browsing, searching, impression formation and matching. In the future work, we will explore the possibilities of supporting tag recom-mendation and tag-based Music Retrieval based on TagClusters.
Abstract: This paper discusses a proposal for the visualization of software evolution, with a focus on combining insight on changes that affect software metrics at project and class level, the project structure, the class hierarchy and the viewing of source code correlated to indirect class coupling. The proposed visualization supports several tasks: the comparison of structural information, including class hierarchies, across several revisions; uncovering collaboration patterns between developers; and determining which classes have been added or deleted to the project during the creation of a given revision. We propose and discuss several design elements supporting these tasks, including interaction patterns and linked views.
Abstract: The analysis of scientific articles produced by different groups of authors helps to identify and characterize research groups and collaborations among them. Although this is a quite studied area, some issues, such as quick understanding of groups and visualization of large social networks still pose some interesting challenges. In order to contribute to this study, we present a solution based in Overlapper, a tool for the visualization of overlapping groups that makes use of an enhanced variation of force-directed graphs. For a real case study, the tool has been applied to articles in the DBLP database.
Abstract: The aim of this paper is to support the awareness of software developers and project managers as regards the evolution of software items by means of the visualization of collaboration between developers and the understanding of the evolution of commercial and open source software items. The proposed design is supported by several interaction techniques and presents detailed information regarding the creation of baselines, branches, revisions and the relationships among them. A case study has been carried out and the usefulness of the tool applied to discover relations and support awareness is revealed through the use of interaction.
Abstract: The use of highly interactive visual tools can provide the benefit of understanding the educational process recorded in the database associated with the current e-learning systems. This is the path followed by ViMoodle, a visual analytical tool whose main function is to support the Moodle e-learning platform.
Abstract: Microarray technology produces large amounts of information to be manipulated by analysis methods, such as biclustering algorithms, to extract new knowledge. All-purpose multivariate data visualization tools are usually not enough for studying microarray experiments. Additionally, clustering tools do not provide means of simultaneous visualization of all the biclusters obtained.
We present an interactive tool that integrates traditional visualization techniques with others related to bioinformatics, such as transcription regulatory networks and microarray heatmaps, to provide enhanced understanding of the biclustering results. Our aim is to gain insight about the structure of biological data and the behavior of different biclustering algorithms.
Abstract: This paper addresses the visualization of the collaboration history in the development of software items using a simple interactive representation called Revision Tree. The visualization presents detailed information on a single software item with the intention of supporting the awareness of the project managers and developers about the item evolution and the collaboration taking place on its development. We considered that repositories of Software Configuration Management tools are the best information source to extract relevant information dealing with the relationships between the programmers and software items, as well as information regarding the creation of baselines, branches and revisions, and useful date and time details for the arrangement of the development timeline and collaboration representation.
Abstract: There are lots of validation indexes and techniques to study clustering results. Biclustering algorithms have been applied in Systems Biology, principally in DNA Microarray analysis, for the last years, with great success. Nowadays, there is a big set of biclustering algorithms each one based in different concepts, but there are few intercomparisons that measure their performance. We review and present here some numerical measures, new and evolved from traditional clustering validation techniques, to allow comparisons and validation of biclustering algorithms.
Abstract: Paleoclimatology requires the analysis of paleo time-series, obtained from a number of independent techniques. Analytical reasoning techniques that combine the judgment of paleoceanographers with automated reasoning techniques are needed to gain deep insights about complex climatic phenomena. This paper presents an interactive visual analysis method based in Parallel Coordinates that enables the discovery of unexpected relationships and supports the reconstruction of climatic conditions of the past.
Abstract: Decade scale oceanic phenomena like El Nino are correlated with weather anomalies all over the globe. Only by understanding the events that produced the climatic conditions in the past will it be possible to forecast abrupt climate changes and prevent disastrous consequences for human beings and their environment. Paleoceanography research is a collaborative effort that requires the analysis of paleo time-series, which are obtained from a number of independent techniques and instruments and produced by a variety of different researchers and/or laboratories. The complexity of these phenomena that consist of massive, dynamic and often conflicting data can only be faced by means of analytical reasoning supported by a highly interactive visual interface. This paper presents an interactive visual analysis environment for paleoceanography that permits to gain insight into the paleodata and allow the control and steering of the analytical methods involved in the reconstruction of the climatic conditions of the past
Abstract: This paper describes the characteristics of a free web-based spectral database for the chemical research community, containing 13C NMR spectra data from more than 4.000 natural compounds. The number of entries is constantly growing. This database allows for searches by chemical structure, substructure, name, family compounds, and by spectral features i.e. chemical shifts and multiplicities, which enable the structural elucidation of known and unknown compounds by comparison of their 13C NMR data.
Abstract: This paper describes a novel and efficient visualization technique intended for hierarchical-temporal data using a tree-ring like layout. Temporal hierarchies appear in numerous fields such as genealogy, evolution taxonomies or time lines. In many cases, state-of-the-art static diagrams are produced in these fields. By using several information visualization strategies, such as focus + context, the tree-ring approach has the ability to visualize and navigate these, potentially complex, hierarchies trough time. Thus, a deeper insight into the problem at hand can be gained.
Abstract: The development of new tools and methodologies is necessary in order to better understand current and past climatic changes,. To be useful, these mathematical or software tools must not remain only in the hands of specialists in statistics, but must also be usable by the larger community of paleoclimatologists. It is therefore necessary to conceive a user interface adapted to the specificities of their use in paleoclimatology. Here, we propose the development of new tools of interactive analysis. Through the combination of techniques coming from knowledge discovery and information visualization (visual data mining), rapid and accurate paleoclimatic reconstructions will be easier to produce.
Abstract: A challenge in ANN research is how to reduce the number of inputs to the model in high dimensional problems, so it can be efficiently applied. The ANNs black-box operation makes not possible to explain the relationships between features and inputs. Some numerical methods, such as sensitivity analysis, try to fight this problem. In this paper, we combine a sensitivity analysis with a linked multi-dimensional visualization that takes advantage of user interaction, providing and efficient way to analyze and asses both the dimension reduction results and the ANN behavior.
Abstract: Many applications in computer graphics require fast and robust collision detection algorithms. The problem of simulating motion in an articulated chain has been well studied using both dynamic and kinematics techniques. This paper describes an efficient method for obstacle representation in the configuration space (C-space) for articulated chains. The method is based on the analytical deconstruction of the C-space, i.e., the separated evaluation of the C-space portion contributed by the collisions of each link. The Deconstruction method is not limited to particular kinematic topologies and allows good collision detection times. The systematic application of a simple convolution of two functions describing each link in the kinematic chain and the workspace, respectively, is applied. The proposed method can naturally face the evaluation of high-dimensional C-spaces, since only non-colliding configurations are considered for the evaluation of the next link in the chain.
Abstract: In this work we present a hierarchical method to evaluate the configuration space of a mobile robot working in large environments. It is based on convolution of discrete functions representing the workspace and the robot to obtain a function that represents the C-space. An important key in the work is that the representation of discrete functions is made by hierarchical data structures, so the information is highly compact, and high dimensions or/and resolutions workspaces can be considered. It is important to highlight that the hierarchical data structures no only have been used for the representation, but for the evaluation. So, intermediate arrays to represent the discrete information are not used in the proposed method. Also, as the method is hierarchical, calculations at high resolutions are performed only in those regions where it is necessary. This makes the method suitable when the robot moves in large environments where other methods will fail due to the memory needs.
Abstract: This paper presents a new general method for obstacle representation in the configuration space (C-space) for redundant robots. The method is based on the analytical deconstruction of the C-space, i.e., the separated evaluation of the C-space portion contributed by the collisions of each link in the kinematic chain. The systematic application of a simple convolution of two functions describing each link and the workspace, respectively, is applied. In order to do that, the transformation of the workspace among reference systems located at one point of each link is needed; in this step a well-known and sound method is used.
Abstract: HESPERIA is an information system for helping in the collaborative research of a multidisciplinary group in the paleoclimatology field. While there exist international databases and information systems that provide long term storage of georeferenced data, they cannot be used during the research stage, since they are limited to published data. The system is designed to manage a collaborative project, keeping track of the shared seabed samples, providing visual analysis and giving the possibility of using partial results. The basic technical structure corresponds to it three tiered client/server architecture that assures scalability and eases long-term maintenance requirements.
Abstract: Currently, the Modern Analog Technique (MAT) is one of the most used techniques in paleoceanography and it is applied for the quantitative reconstruction of environmental conditions of the past. Through the calculation of distances between modern and paleo data, patterns (analogs) are found, and after an interactive analysis, paleoenvironmental features are reconstructed. PaleoAnalogs is a powerful and flexible tool, developed with Java technology, making it a multiplatform tool to be executed in any operating system; the tool can automatically take on the appearance and behavior of whatever operating system it happens to be running under; it is an interactive tool that permits 3D plots helping the analysis of three variables); it Includes 8 different types of distance measures; it is designed to carry out the reconstructions using different distance coefficients and for helping in the comparison between different results; and it provides a wizard for making associations (equivalent taxa, additions) of taxonomic categories between the modern data and the fossil data.
Abstract: In this work we present a hierarchical algorithm to evaluate the configuration space of a mobile robot. Although it is based on discrete convolution of workspace and robot, quadtree representations have been introduced in order to obtain directly a quadtree representation of the C-space. Because these representations compact highly the information, it can be used for workspaces with high dimensions or/and resolutions. Also, as the algorithm is hierarchical, calculations at high resolutions are performed only in those regions where it is necessary.
Abstract: In this paper we present an analysis that indentifies opportunities of introducing parallelism in the calculation of the configuration space. When the Convolution Theorem is used for this evaluation, two levels have appeared within the basic operation of the algorithms and another one for the employed computational tool (Fast Fourier Transform, FFT). The method has been applied to robots moving on a plane in a 3D workspace. As a result, an optimal reduction of the calculation time is obtained: the parallel implementation, working on a tetra-processor, is more than three times faster than the sequential one. Finally, it can be added that the proposed design for the parallel algorithm is general and easily implementable for articulated robots.
Abstract: In order to monitor and make predictions, palaeoceanographers need to manipulate, integrate and analyse paleo time-series that are obtained from a number of independent techniques and instruments which, moreover, are usually produced by different researches and/or laboratories. The result is a collection of datasets with unequal age precision. This situation worsens since, at present, there is not an assembly of integrated tools that permits the palaeontologists to perform a study without having to use applications of different natures (spreadsheets, image editors, time-series analysers, etc.) which are of general purpose and, usually, expensive and platform-dependent. Hence, the goal of this project was to develop a platform-independent full featured tool that could simplify the palaeocenographers work, being used during the whole process: from the beginning, merging and correlating different datasets, continuing with interactive analyses, to the end, plotting the results. PaleoPlot is a general tool which could be used for any kind of time series, although it is optimised for the use in the stratigraphy area. Finally, it must be said that PaleoPlot is currently been used as an educational tool on palaeontology courses at the University of Salamanca.
Abstract: Ocean dynamics modeling is essential for predicting the impact of climatic change on human activities. The need of large time series (e. g., paleoclimatic data) has been exposed as one of the challenges to embark on decadal climate predictability. The goal of this study was to reconstruct the surface water dynamics in the China sea during the last 130,000 years. In order to do that it was necessary the assembly of integrated comprehensive datasets obtained from a gravity core recovered in the Sunda Slope (South China Sea) using different techniques such as quantitative analyses from coccolithophores, stable isotopes and biomarkers. Thanks to data mining, through a variety of data analysis tools, from Silicon Graphics' Mineset, such as Decision trees and Clustering we have established the variations in the water column stratification (relative position of nutricline/thermocline). This study is a good example of combining data mining and paleoceartography to explain some general paleodynamics, including short-time events, showing the potential to monitor and predict in the context of decadal time-series.
Abstract: In this paper it is shown a practical method wich lets evaluate the full set of robot configurations that produce collisions between the environment and the cylindrical manipulator. The method is based on a sound mathematical formalism so the feasibility of the results is guaranteed. The application of the formalism is performed by means of choosing a suitable coordinate functions, in the workspace, as well as in the configuration space. It leads to the fact that the obstacle representation in the configuration space could be seen as a convolution of two functions that describe the cylindrical robot and the obstacles respectively. Additionally, the computational load is independent of the shape and number of obstacles and of the robot shape. The algorithmic tool that has been used is FFT (Fast Fourier Transform), since it eases the parallel implementation of the resulting algorithms reducing significantly the computational load, so the computational time is highly optimized.
Abstract: In this work we present a new algorithm to perform the configuration space of a robot. Although it is based on convolution of matrixes of workspace and robot, the use of quadtree representations for them is introduced in order to obtain a quadtree representation of the C-space. Then, an efficient use of memory can be achieved because these representations compact highly the information. So, it can be used for workspaces with high dimensions or/and resolutions. As a first approach, in this paper it is presented for the use on a mobile robot without rotations, although it can be applied to more complex situations. Copyright (C) 2001 IFAC.
Abstract: In this article it is presented the design and implementation of algorithms for the calculation of the configuration space for a robot upon a distributed computing system. In these algorithms two levels of parallelism appear: for the basic level of operation of the proposed algorithm and for the level of the computational tool utilized -Fast Fourier Transform (FFT). The library complib.sgimath has been used. In the method employed to carry out the paralellization the master-slave philosophy is followed, using a message-passing library (MPI). Taking as case of study a robot that moves upon a plan, it is carried out a load balance and the influence of the granularity is analyzed or a master and various slave processes over a tetraprocessor SGI Origin 200. In this way, it is obtained a reduction of the calculation time, for the best solution, to a third part of the employed time in the implementation of the secuential algorithm, showing the line to follow for the significant reduction of the calculation times.
Abstract: In this paper it is shown a practical method wich lets evaluate the full set of crane configurations that produce collisions between the construction environment and the crane and its load. The method is based on a sound mathematical formalism so the feasibility of the results is guaranteed. Moreover, a suitable application of the formalism is performed in this work by means of choosing a suitable coordinate functions, in the workspace, as well as in the configuration space. It leads to the fact that the obstacle representation in the crane configuration space could be seen as a convolution, of two functions that describe the crane-robot and the obstacles respectively, Additionally, the computational load is independent of the shape and number of obstacles and of the robot shape, The algorithmic tool that has been used is FFT (Fast Fourier Transform), since it eases the parallel implementation of the resulting algorithms reducing significantly the computational load, so the computational time is highly optimized.
