Estimados
Están cordialmente invitados al inicio del Ciclo de Charlas de Postgrado del semestre, la que se realizará el próximo miércoles 8 de Abril, a las 13:30 hrs. en la sala de clases de nuestro Departamento.
Se presentarán:
**Dabne Barrera T.** Alumna de Magíster del área Sistemas de Información, profesor(a) supervisor(a) Claudia Prieto.
Título: "Highly efficient simultaneous 3D joint T1-T2 mapping of the knee at 0.55T: Comparison of Cartesian and radial strategies".
Abstract: To develop and compare two novel 3D frameworks for simultaneous T1-T2 mapping of knee hyaline articular cartilage at 0.55T in ~4 min.
Two 3D T1-T2 mapping sequences were optimized at 0.55T: (i) Cartesian acquisition using VD[1]CASPR trajectory with inversion-recovery (IR) and T2preparations; and (ii) free-running golden[1]angle radial acquisition interleaving IR and IRT2prep. Undersampled data were reconstructed using iterative-SENSE with HD-PROST regularization. T1-T2 maps were generated via dictionary matching. Validation included phantom and 10 healthy volunteers, compared to references. Accuracy, precision, intra-session repeatability, map-sharpness, and reconstruction[1]time were evaluated.
Both frameworks achieved whole-knee coverage at 1mm isotropic resolution in 3:48 min (Cartesian) and 3:40 min (radial). Phantom T1-T2 estimates correlated well with references (R² = 0.99) and good Bland-Altman agreement. In-vivo cartilage T1 were comparable to MOLLI, while both approaches exhibited systematically lower T2 than 2D T2-prepared-bSSFP, consistent with known bSSFP bias. Variability was low (CV ~0.10–0.15 for T1; ~0.10-0.20 ms for T2) with the radial approach showing the lowest T2 variability. Intra-session repeatability was high, with no significant differences between repeated scans (p > 0.05). The Cartesian approach provided sharper maps and faster reconstruction (~1.6 h vs ~3.7 h). Proposed frameworks enable rapid, isotropic knee cartilage quantification at 0.55T in ~4 minutes, with accurate, precise, and repeatable measurements.
-------------------------------
**José I. Gajardo R.** Alumno de Doctorado del área Energía, profesor supervisor Javier Pereda.
Título: "Optimized Modulation Strategies for Parallel Converters".
Abstract: With the increase in variable renewable generation installations and energy storage systems, the power converter market has experienced—and is expected to continue experiencing—significant growth in the coming years. Most of the market is composed of two- or three-level inverters. When power requirements increase, the parallelization of inverters is the solution offered by many power electronics companies. However, despite its economic advantages, this approach presents major drawbacks, as it compromises overall system efficiency and stability due to the emergence of parasitic or circulating currents between inverters, especially in photovoltaic and battery systems. Modulation is essential in inverters, as it shapes key physical phenomena within the system, such as common-mode voltage and energy losses. Techniques like Harmonic Programmed PWM (HPM) enable modulation optimization and improve inverter performance. However, the benefits of such techniques have so far been demonstrated only at low switching frequencies, which is not the case in low-voltage systems employing new semiconductor technologies (SiC and GaN). As a result, commercial power converters continue to rely on strategies like DPWM and address associated challenges through hardware solutions, which increases system cost. The general objective of this thesis project is to develop and validate optimal modulation strategies that reduce hardware costs and improve current solutions in terms of efficiency and industrial requirements.
Habrá colación y bebida para los asistentes por lo que la asistencia será controlada. Los esperamos a las 13:30 hrs. Si vas a participar, favor inscríbete en el siguiente link y especifica si tienes alguna restricción alimentaria:
https://indico.ing.puc.cl/event/322/
Atentos saludos,
MATÍAS NEGRETE