Sergio Colcher

Daniel de S. Moraes, Pedro T. C. Santos, Polyana B. da Costa et al.

This work presents an unsupervised method for automatically constructing and expanding topic taxonomies using instruction-based fine-tuned LLMs (Large Language Models). We apply topic modeling and keyword extraction techniques to create initial topic taxonomies and LLMs to post-process the resulting terms and create a hierarchy. To expand an existing taxonomy with new terms, we use zero-shot prompting to find out where to add new nodes, which, to our knowledge, is the first work to present such an approach to taxonomy tasks. We use the resulting taxonomies to assign tags that characterize merchants from a retail bank dataset. To evaluate our work, we asked 12 volunteers to answer a two-part form in which we first assessed the quality of the taxonomies created and then the tags assigned to merchants based on that taxonomy. The evaluation revealed a coherence rate exceeding 90% for the chosen taxonomies. The taxonomies' expansion with LLMs also showed exciting results for parent node prediction, with an f1-score above 70% in our taxonomies.

Luis Felipe M. O. Henriques, Eduardo Morgan, Sergio Colcher et al.

Non-Intrusive Load Monitoring (NILM) is a computational technique to estimate the power loads' appliance-by-appliance from the whole consumption measured by a single meter. In this paper, we propose a conditional density estimation model, based on deep neural networks, that joins a Conditional Variational Autoencoder with a Conditional Invertible Normalizing Flow model to estimate the individual appliance's power demand. The resulting model is called Prior Flow Variational Autoencoder or, for simplicity PFVAE. Thus, instead of having one model per appliance, the resulting model is responsible for estimating the power demand, appliance-by-appliance, at once. We train and evaluate our proposed model in a publicly available dataset composed of power demand measures from a poultry feed factory located in Brazil. The proposed model's quality is evaluated by comparing the obtained normalized disaggregation error (NDE) and signal aggregated error (SAE) with the previous work values on the same dataset. Our proposal achieves highly competitive results, and for six of the eight machines belonging to the dataset, we observe consistent improvements that go from 28% up to 81% in NDE and from 27% up to 86% in SAE.

Rafael Diniz, Alan L. V. Guedes, Sergio Colcher

ISDB-T International standard is currently adopted by most Latin America countries and is already installed in most TV sets sold in recent years in the region. To support interactive applications in Digital TV receivers, ISDB-T defines the middleware Ginga. Similar to Digital TV, Digital Radio standards also provide the means to carry interactive applications; however, their specifications for interactive applications are usually more restricted than the ones used in Digital TV. Also, interactive applications for Digital TV and Digital Radio are usually incompatible. Motivated by such observations, this report considers the importance of interactive applications for both TV and Radio Broadcasting and the advantages of using the same middleware and languages specification for Digital TV and Radio. More specifically, it establishes the signaling and definitions on how to transport and execute Ginga-NCL and Ginga-HTML5 applications over DRM (Digital Radio Mondiale) transmission. Ministry of Science, Technology, Innovation and Communication of Brazil is carrying trials with Digital Radio Mondiale standard in order to define the reference model of the Brazilian Digital Radio System (Portuguese: Sistema Brasileiro de Rádio Digital - SBRD).