Proyectos

En este proyecto se busca diseñar técnicas para resolver problemas de optimización polinomial. Este tipo de modelos está dentro de los modelos de optimización más complejos y poseen una amplia gama de importantes aplicaciones.

En este proyecto se busca diseñar técnicas para resolver problemas de optimización polinomial. Este tipo de modelos está dentro de los modelos de optimización más complejos y poseen una amplia gama de importantes aplicaciones.

En la presente postulación, se propone la incorporación al Instituto de Ciencias de la Ingeniería de la Universidad de O’Higgins de la Dra. Tania Villaseñor Jorquera quien tiene una trayectoria académica destacada y un plan de docencia e investigación que aporta de forma sustantiva al desarrollo de la institución. La propuesta considera la investigación de procesos de erosión y transporte de sedimento en Chile central en relación al cambio climático y la actividad antrópica. En este proyecto, se monitoreará el flujo de sedimento en diferentes sectores de las cuencas de los ríos Maipo e Itata a través del análisis de proveniencia de sedimento fluvial con el fin de detectar variabilidad en las zonas que aportan sedimento y los mecanismos de transporte desde la cordillera hacia el océano. También se analizarán registros sedimentarios marinos para construir una línea base del funcionamiento de los sistemas sedimentarios en el pasado reciente. Esta línea de investigación tiene impacto directo en problemáticas de la zona centro de Chile, como la erosión, el transporte de contaminantes, procesos de remoción en masa, y propiciará colaboraciones interdisciplinarias entre académicos de la Universidad así como con investigadores de otras instituciones nacionales e internacionales. Esta propuesta de investigación, sumado a la experiencia docente de Tania, fortalecerá el grupo académico del Instituto, en particular el de la carrera de Ingeniería Civil Geológica. Las redes de trabajo internacional de Tania permitirán fortalecer el programa de internacionalización de la Universidad de O’Higgins. Por otra parte, su experiencia en divulgación de la ciencia resulta muy atractivo para potenciar el proceso de vinculación con el medio, de gran importancia para la misión de la Universidad. Todos estos aspectos contribuirán de forma importante a la proyección de la Universidad de O’Higgins como referente científico y académico para la región y el país.

Desarrollo de habilidades de lenguaje y matemáticas en niños con diagnóstico de TEL de estudiantes de primer año básico en la región de O'Higgins

Desarrollo de habilidades de lenguaje y matemáticas en niños con diagnóstico de TEL de estudiantes de primer año básico en la región de O'Higgins

Desarrollo de habilidades de lenguaje y matemáticas en niños con diagnóstico de TEL de estudiantes de primer año básico en la región de O'Higgins

Overview: We have recently observed that shear shock waves are generated and subsequently propagate in the brain under impact conditions that are quite general. For example, a 35g impact, which is in the concussive range, propagates nonlinearly in the brain and develops into a thin, destructive 300g shock front. This highly localized increase in acceleration suggests that shear shock waves are a fundamental mechanism for traumatic injuries in the brain and in soft tissue. These observations were made with ultrasonic methods that we have developed based on clutter reducing high frame-rate (10,000 images/second) imaging sequences and high sensitivity (better than 1 micrometer) motion tracking algorithms. This imaging method offers a unique combination of imaging speed, accuracy, and penetration that interrogates a spatiotemporal regime not accessible to other imaging modalities. On the other hand, the physics of nonlinear elastic waves in soft solids has been practically unexplored. In particular, just a few theoretical papers have addressed the generation of nonlinear surfaces waves in soft solids. None experimental research has reached to the complete observation of nonlinear surface wave in soft solids. Therefore, the physics of the propagation of nonlinear surfaces waves and its consequences on soft solid, presents many experimental, theoretical, and numerical opportunities for investigation. With applications in the biomechanics of injuries as well as in geophysics due to that most of the damage produced by an earthquake is due to surface waves because they spread energy more efficiently. Goals: The general objective of this proposal is to reveal the physics governing the propagation of nonlinear surface waves in soft solids. The origin of the nonlinearity in these waves is unclear. Few authors suggest that it comes only from a geometrical effect due to the definition of the nonlinear strain tensor. However, at increased amplitudes, we hypothesize that the material nonlinearity also should play a role. The effect of these two nonlinear components is unknown. It has been predicted that the nonlinearity might distort the wave profile producing discontinuities in the particle displacement velocity or acceleration. Until now, no experimental clues about the conditions and parameters that generate these discontinuities have been found. Another open question in this topic is related to the penetration depth. Surface wave typically penetrates few wavelengths within the surface of propagation. However, in soft solids, typical wavelength are in the order of centimeters, making the penetrating wave an important subject of study. The effect of the nonlinear distortion with depth is unknown and an aim of this proposal. Thus, here we propose to develop models, theory and experiments that elucidate this questions and give us a clear picture of the behavior of these waves in soft materials like gelatin. Methodology: Unlike compressional shocks in fluids, elastic waves, such as surface waves, are practically unexplored due to the experimental challenges associated with observing waves at depth in solids. Current observations of surface waves are confined only at the free surface and restricted only to Rayleigh waves. Surface waves in other interfaces such as solid-fluid or solid-solid have not been experimentally explored in soft solids yet. Advanced ultrasound imaging techniques implemented on a highly customized imaging platform designed for high frame-rate imaging will be used to characterize fundamental surface wave physics in homogeneous soft solids. These observations and characterizations of nonlinear surface waves will be achieved with a number of steps that integrate advancements in ultrasound imaging, advancement in algorithms that measure the deformation and advancements in modeling. The advancement on the visualization of displacements will be validated using a fringe projection profilometry system, based on a high frame rate camera. We will perform experiments in the linear regime to characterize attenuation and dispersion, which interact with the nonlinearity and therefore, have a significant impact on the resulting kinematic of the medium, due to their frequency dependent nature. Custom two-dimensional imaging sequences, designed for shock wave tracking, will be implemented for a dedicated Linear array transducer that has 128 elements and can reach a spatial resolution of 200 microns at very high frame-rate in the order of 10000 frames per second. This ultrasound technology does not exist until now in Chile. Expected results: The results of this proposal will elucidate the origin of the nonlinear response of soft materials for the surface waves. We expect that at sufficiently high amplitude the material nonlinearity will be expressed. Additionally, due to the distortions of the wave profile generated by the nonlinearity, we expect to observe discontinuous particle displacement, velocity and/or acceleration. These discontinuities will be classified as a new type of shock wave. We hope to see that this new type of shock wave propagates over a longer distance than the compressional shock or shear shock, principally due to that surface waves spread reducing its amplitude proportionally to the square root of the propagation distance instead of typical reduction proportional to the propagation distance observed in bulk waves. We also expect the shock waves associated with surface waves are more likely to produce fracture or catastrophic event in soft solids. In the context of linear wave propagation, we expect to measure the power laws that govern the frequency dependent attenuation and dispersion for surface waves. If successful, this research would suggest the nonlinear surface waves as a new mechanism for injury. In addition, this research could become a platform to test shock wave ideas that are very difficult to prove in compressional waves. Thus, it would serve as an analogous physical system to study shock waves in general.