Search results for "Retrieval"
showing 10 items of 1176 documents
Methods for defining user groups and user-adjusted information structures
1999
A common problem in the design of information systems is how to structure the information in a way that is most useful to different groups of users. This paper describes some statistical methods for revealing the structure inherent in empirical data elicited from users. It is illustrated by the application of these methods to the design of some web pages giving information about the Universitat de Valencia. Three potential user groups were identified, administrative staff, teaching staff and students. The first analysis demonstrated that users within these three groups assign relatively homogeneous structures, but that the structures assigned by the three groups are not the same, and also, …
Boolean operations with implicit and parametric representation of primitives using R-functions
2005
We present a new and efficient algorithm to accurately polygonize an implicit surface generated by multiple Boolean operations with globally deformed primitives. Our algorithm is special in the sense that it can be applied to objects with both an implicit and a parametric representation, such as superquadrics, supershapes, and Dupin cyclides. The input is a constructive solid geometry tree (CSG tree) that contains the Boolean operations, the parameters of the primitives, and the global deformations. At each node of the CSG tree, the implicit formulations of the subtrees are used to quickly determine the parts to be transmitted to the parent node, while the primitives' parametric definition …
Educación y Sostenibilidad en la Universidad de Valencia: construyendo futuro desde el pasado
2019
Una práctica académica de calidad en educación superior requiere estructuras institucionales que apoyen los principios de la Sostenibilidad y los lleven a la práctica, pero también requiere profesorado que esté motivado y capaz de impregnar su forma de enseñar y las materias que enseña desde criterios y valores relacionados con la sostenibilidad. El contexto de este trabajo es la educación e investigación para la sostenibilidad (EIpS) en la Universitat de València (UV) en los últimos 12 años. El método utilizado ha sido el Análisis de documentos que siguiendo los criterios de pertinencia, exhaustividad y actualidad ha permitido encontrar la información necesaria para desarrollar el estudio …
Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography.
2005
In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous…
Three-dimensional phase unwrapping using the Hungarian algorithm.
2009
We propose a three-dimensional phase unwrapping technique that uses the Hungarian algorithm to join together all the partial residual loops that may occur in a wrapped phase volume. Experimental results have shown that the proposed algorithm is more robust and reliable than other well-known three-dimensional phase unwrapping algorithms. Additionally, the proposed algorithm is fast in terms of computational complexity, which makes it suitable for practical applications.
Robust three-dimensional best-path phase-unwrapping algorithm that avoids singularity loops.
2009
In this paper we propose a novel hybrid three-dimensional phase-unwrapping algorithm, which we refer to here as the three-dimensional best-path avoiding singularity loops (3DBPASL) algorithm. This algorithm combines the advantages and avoids the drawbacks of two well-known 3D phase-unwrapping algorithms, namely, the 3D phase-unwrapping noise-immune technique and the 3D phase-unwrapping best-path technique. The hybrid technique presented here is more robust than its predecessors since it not only follows a discrete unwrapping path depending on a 3D quality map, but it also avoids any singularity loops that may occur in the unwrapping path. Simulation and experimental results have shown that …
Hybrid robust and fast algorithm for three-dimensional phase unwrapping
2009
We present a hybrid three-dimensional (3D) unwrapping algorithm that combines the strengths of two other fast and robust existing techniques. In particular, a branch-cut surface algorithm and a path-following method have been integrated in a symbiotic way, still keeping execution times within a range that permits their use in real-time applications that need a relatively fast solution to the problem. First, branch-cut surfaces are calculated, disregarding partial residue loops that end at the boundary of the 3D phase volume. These partial loops are then used to define a quality for each image voxel. Finally, unwrapping proceeds along a path determined by a minimum spanning tree (MST). The M…
Exploring the Link between ICT and Development in the Context of Developing Countries : A Literature Review
2014
Published version of an article in the journal: Electronic Journal of Information Systems in Developing Countries. Also available from the publisher at: http://www.ejisdc.org/ojs2/index.php/ejisdc/article/view/1332. Open Access The article contributes to the ongoing discussion on relating information and communication technology (ICT) to development (D). The quest to relate ICT to D is a topic of open deliberation and critical scrutiny in ICT4D research communities. To enhance the understanding in this regard, we conducted a literature review. The review examines 80 articles to identify various development theories and the role of technologies in the development process. While scanning the …
Environmental taxation, information precision, and information sharing
2022
We analyze how environmental taxes should be optimally levied when the regulators and firms face costs uncertainties in a Stackelberg-Cournot game. We allow linear-quadratic payoffs functions coupled with an affine information structure encompassing common and private information with noisy signals. In the first period, the regulator chooses the intensity of emissions taxes in order to reduce externalities. In the second period, facing industry-related and firm-specific shocks, firms compete in the marketplace as Cournot rivals and choose outputs. We show that, given costs uncertainties with non-uniform quality of signals across firms, the regulator sets differentiated tax policy. We also e…
Assessment and inter-comparison of recently developed/reprocessed microwave satellite soil moisture products using ISMN ground-based measurements
2019
Soil moisture (SM) is a key state variable in understanding the climate system through its control on the land surface energy, water budget partitioning, and the carbon cycle. Monitoring SM at regional scale has become possible thanks to microwave remote sensing. In the past two decades, several satellites were launched carrying on board either radiometer (passive) or radar (active) or both sensors in different frequency bands with various spatial and temporal resolutions. Soil moisture algorithms are in rapid development and their improvements/revisions are ongoing. The latest SM retrieval products and versions of products that have been recently released are not yet, to our knowledge, com…