Repositorio UFT :: Examinando por Autor "Paredes, Rodrigo"

Examinando por Autor "Paredes, Rodrigo"

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A new dynamic, secondary-memory metric index
(Red de Universidades Nacionales con carreras en Informática (RedUNCI); Universidad Nacional de la Plata, 2024-10-07) Paredes, Rodrigo; Reyes, Nora Susana; Figueroa, Karina; Hoffhein, Manuel
Metric space searching addresses the problem of efficient similarity searching in many applications. Although promising, the metric space approach is still immature in several aspects that are well established in traditional databases. Particularly, most indexing schemes are not dynamic, that is, few of them tolerate insertion of elements at reasonable cost over an existing index with none or mild performance degrading; and even less of them work efficiently in secondary memory. The List of Clusters (LC) is a competitive index in main memory. We introduce a new dynamic, secondary-memory variant of the LC. Our new index handles well the secondary memory scenario and is competitive with the state of the art, becoming a useful alternative in a wide range of database applications. Also, our ideas are applicable to other secondary-memory indexes, where it is possible to control the disk page occupation.
A Sub-Hourly Precipitation Dataset from a Pluviographic Network in Central Chile
(MDPI, 2025-06-22) Sangüesa, Claudia; Ibañez, Alfredo; Pizarro, Roberto; Vidal-Silva, Cristian; Garcia-Chevesich, Pablo; Mendoza, Romina; Toledo, Cristóbal; Pino, Juan; Paredes, Rodrigo; Ingram, Ben
This data descriptor presents a unique high-resolution rainfall dataset derived from 14 pluviograph stations across central Chile’s Mediterranean region, covering variable peri- ods starting from between 1969 and 1992, up to 2009. The dataset provides continuous precipitation records at a 5 min temporal resolution, obtained through the digitization and processing of pluviograph strip charts using specialized software. This high temporal resolution is unprecedented for the region and enables detailed analysis of rainfall inten- sity, duration, and frequency patterns critical for hydrological research, climate studies, and water resource management in general. Each station’s data was subjected to quality control procedures, including manual validation and correction of digitization errors to ensure data integrity. The dataset reveals the significant temporal variability of rainfall in central Chile, capturing both short-duration high-intensity events and longer precipi- tation patterns. By making this dataset publicly available, we provide researchers with a valuable resource for studying rainfall behavior in a Mediterranean climate zone subject to significant climate variability and change. The dataset supports various applications, including the development of intensity–duration–frequency curves, analysis of rainfall erosivity, calibration of hydrological models, and investigation of precipitation trends in the context of climate change.
BOLDSC: A New Dynamic, Secondary-Memory Metric Index
(Springer Nature, 2025-10-01) Paredes, Rodrigo; Reyes, Nora; Figueroa, Karina; Hoffhein, Manuel
Metric space searching addresses the problem of efficient similarity searching across diverse applications, in particular for non-structured objects, for instance, natural language or images. Although promising, this approach is still immature in several aspects that are well-established in traditional databases. Particularly, most indexing schemes are not dynamic, as they cannot efficiently handle insertions over an ongoing index without significant performance degradation. Moreover, very few of them work efficiently in secondary memory. The List of Clusters (LC) has proven to be a competitive index in main memory due to its simplicity and good search performance in high dimensional metric spaces. We introduce a new dynamic, secondary-memory LC variant. Our new index efficiently handles the secondary memory scenario and achieves competitive search and insertion times compared to the state-of-the-art, making it a practical alternative for large-scale database applications. Also, our ideas are applicable to other secondary-memory indexes, where it is possible to control the disk page occupation.
Limitations of transfer learning for chilean cherry tree health monitoring: when lab results do not translate to the orchard
(MDPI, 2025-08-13) Hidalgo, Mauricio; Yanine, Fernando; Galleguillos Silva, Renato Bruno; Lagos, Miguel; Kumar Sahoo, Sarat; Paredes, Rodrigo
Chile, which accounts for 27% of global cherry exports (USD 2.26 billion annually), faces a critical industry challenge in crop health monitoring. While automated sensors monitor environmental variables, phytosanitary diagnosis still relies on manual visual inspection, leading to detection errors and delays. Given this reality and the growing use of AI models in agriculture, our study quantifies the theory–practice gap through comparative evaluation of three transfer learning architectures (namely, VGG16, ResNet50, and EfficientNetB0) for automated disease identification in cherry leaves under both controlled and real-world orchard conditions. Our analysis reveals that excellent laboratory performance does not guarantee operational effectiveness: while two of the three models exceeded 97% controlled validation accuracy, their field performance degraded significantly, reaching only 52% in the best-case scenario (ResNet50). These findings identify a major risk in agricultural transfer learning applications: strong laboratory performance does not ensure real-world effectiveness, creating unwarranted confidence in model performance under real conditions that may compromise crop health management.
Manual de usuario: Software de diseño de zanjas de infiltración
(Cátedra UNESCO; Universidad de Talca; Centro Nacional para la Industria de la Madera., 2025-03-31) Ingram, Ben; Córdova, Alfredo Ibáñez; Pizarro Tapia, Roberto; Sangüesa Pool, Claudia; Paredes, Rodrigo; Toledo Acevedo, Cristóbal
En un contexto de creciente pérdida de suelos por erosión hídrica, reducción de la recarga natural de acuíferos y de desertificación de territorios, se hace necesario contar con herramientas computacionales que faciliten el diseño de obras para mitigar la expansión de zonas desertificadas y la disminución de aguas subterráneas. En respuesta a esta necesidad, la Cátedra Unesco en Hidrología de Superficie de la Universidad de Talca (CUHS) desarrolló un software que permite estimar las dimensiones y el distanciamiento óptimos de las zanjas de infiltración para un sitio determinado, con el objetivo de reducir el tiempo empleado en su diseño e implementación. El software aborda los siguientes aspectos: • Estimación hidrológica de las dimensiones de las zanjas de infiltración. • Cálculo del distanciamiento óptimo entre zanjas. • Adaptación a diferentes condiciones del terreno y de precipitación.
Mathematical model for the plastic flow and ductile fracture of polycrystalline solids
(Elsevier, 2024-01-25) Lagos, Miguel; Retamal, César; Valle, Rodrigo; Paredes, Rodrigo
It is mathematically shown that ductile fracture after finite plastic strain is a necessary consequence of the polycrystalline nature of the materials. A closed–form equation for the plastic strain to fracture of a fine–grained polycrystal with no voids is derived. The mathematical model for the plastic deformation is grounded on the physical hypothesis that adjacent grains slide with a relative velocity proportional to the local shear stress resolved in the plane of the shared grain boundary, when exceeds a finite threshold. Hence plastic flow is governed predominantly by the in–plane shear forces making grain boundaries to slide, and the induced local forces responsible for the continuous grain reshaping are much weaker. The process is shown to produce a monotonic hydrostatic pressure variation with strain that precludes a stationary flow. The hydrostatic pressure dependence on strain has two solutions. One of them leads to superplasticity, the other one is shown to diverge logarithmically at a finite fracture strain and then represents ductile behaviour. Emphasis is done in the mathematical aspects of the deformation of the polycrystal up to the initiation of fracture. Although theoretical predictions agree well with mechanical tests of commercial alloys, technical issues like the effects of the presence and evolution of porosity and other imperfections, or how fracture evolves after initiation are left for a more specific communication.
Oscillations and Waves
(Institute of Physics (AIP) Publishing, 2024-12-01) Lagos, Miguel; Paredes, Rodrigo; Elgueta, Milton; Molina, Mario
Oscillations and waves are prevalent in the realm of physical sciences, finding applications across a wide range of technical fields. Waves can be observed everywhere, primarily due to the fact that the lowest-energy states of most spatially extended physical systems tend to exhibit wave-like characteristics. Oscillation can be regarded as a fundamental component of wave motion. It is evident in various scenarios, such as the movement of a suspended object, subtle fluctuations in air pressure within a noisy environment, or the gentle ripples on the surface of a quiet pond. Even in more intricate systems, like the dynamics of the electromagnetic field, we consistently observe the tangible consequences of oscillations and waves. For this reason, it is highly desirable to introduce the study of physical systems governed by waves at an early stage, as it fosters a sense of comprehension regarding complex aspects of real-life phenomena. The issue at hand is that the conventional exploration of oscillations and waves requires mathematical techniques that are still unfamiliar to students at the introductory level. However, the next sections aim to provide a theoretical introduction to oscillations and waves without relying on advanced mathematics, ensuring that no physical rigor is sacrificed. The article seeks to help teachers motivate students with a special interest in science.
What Is the Process? A Metamodel of the Requirements Elicitation Process Derived from a Systematic Literature Review
(MDPI, 2024-12-25) Hidalgo Barrientos, Mauricio Fernando; Yanine, Fernando; Paredes, Rodrigo; Frez, Jonathan; Solar, Mauricio
Requirements elicitation is a fundamental process in software engineering, essential for aligning software products with user needs and project objectives. As software projects become more complex, effective elicitation methods are vital for capturing accurate and comprehensive requirements. Despite the variety of available elicitation methods, practitioners face persistent challenges such as capturing tacit knowledge, managing diverse stakeholder needs, and addressing ambiguities in requirements. Moreover, although elicitation is recognized as a core process for gathering and analyzing system objectives, there is a lack of a unified and systematic framework to guide practitioners—especially newcomers—through the activity. To address these challenges, we provide a comprehensive analysis of existing elicitation methods, aiming to contribute to better alignment between software products and project objectives, ultimately improving software engineering practices. We do so by performing a systematic literature review identifying crosscutting steps, common techniques, tools, and approaches that define the core activities of the elicitation process. We synthesize our findings into a metamodel that structures software elicitation processes. This review uncovers various elicitation methods—such as collaborative workshops, interviews, and prototyping—each demonstrating unique strengths in different project contexts. It also highlights significant limitations, including stakeholder misalignment and incomplete requirements capture, which continue to reduce the effectiveness of elicitation processes. Finally, our study seeks to contribute to understanding requirements elicitation methods by providing a comprehensive view of their current strengths and limitations through a metamodel enabling the structuring and optimization of elicitation processes.
Wildfire Occurrence and Damage Dataset for Chile (1985–2024): A Real Data Resource for Early Detection and Prevention Systems
(MDPI, 2025-06-20) Vidal-Silva, Cristian; Pizarro, Roberto; Castillo-Soto, Miguel; De la Fuente, Claudia; Duarte, Vannessa; Sangüesa, Claudia; Ibañez, Alfredo; Paredes, Rodrigo; Ingram, Ben
Wildfires represent an increasing global concern, threatening ecosystems, human settle- ments, and economies. Chile, characterized by diverse climatic zones and extensive forested areas, has been particularly vulnerable to wildfire events over recent decades. In this con- text, real, long-term data are essential to understand wildfire dynamics and to design effective early warning and prevention systems. This paper introduces a unique dataset containing detailed wildfire occurrence and damage information across Chilean municipal- ities from 1985 to 2024. Derived from official records by the National Forestry Corporation of Chile CONAF, this dataset encompasses key variables such as the number of fires, to- tal burned area, estimated material damages, and the number of affected individuals. It provides an invaluable resource for researchers and policymakers aiming to improve fire risk assessments, model fire behavior, and develop AI-driven early detection systems. The temporal span of nearly four decades offers opportunities for longitudinal analyses, the study of climate change impacts on fire regimes, and the evaluation of historical prevention strategies. Furthermore, by presenting a complete spatial coverage at the municipal level, it allows fine-grained assessments of regional vulnerabilities and resilience.

Examinando por Autor "Paredes, Rodrigo"

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