The use of the rice hull is minimal in most of the Latin American countries and only a small port... more The use of the rice hull is minimal in most of the Latin American countries and only a small portion is used as fertilizer or fuel. However, products of rice hull obtained by pyrolysis can be useful for abrasive and refractory products based on silicon carbide (SiC). Recently some applications have been developed to use SiC as reinforcement for metallic alloys for metal matrix composites. This paper reports the synthesis of short fibers and small particles of SiC obtained by controlled combustion of rice hull. The SiC synthesis was performed in a gas furnace, designed during the research. This process was optimized by an experimental design which included as variables the temperature, pyrolysis time, the type of catalyst, and process atmosphere.
Este artículo revisa los materiales compuestos de matriz metálica (CCM) usados en las industrias ... more Este artículo revisa los materiales compuestos de matriz metálica (CCM) usados en las industrias eléctrica y electrónica. Usualmente, los composites útiles en estos sectores corresponden a la familia de las aleaciones ligeras, reforzadas con fibras o partículas. Por tal motivo, la revisión está enfocada en las aleaciones Al, Ti y Mg, sus propiedades y aplicaciones.
Mechanical, chemical and thermal properties of thermoset materials such as epoxy resins are condi... more Mechanical, chemical and thermal properties of thermoset materials such as epoxy resins are conditioned by cure schedule. There are different techniques to determine the resin conversion level during process such as Fourier-transform infrared spectroscopy (FTIR); in this study we analyze the curing of two comercial systems of DGEBA/DDM by this technique. The conversion level of epoxy groups was evaluated employing
A generation of new models has been proposed to handle some complex human behaviors. These models... more A generation of new models has been proposed to handle some complex human behaviors. These models account for the data ambiguity, and therefore extend the application field of the discrete choice modeling. The facial expression recognition (FER) is highly relevant in this context. We develop a dynamic facial expression recognition (DFER) framework based on discrete choice models (DCM). The DFER consists in modeling the choice of a person who has to label a video sequence representing a facial expression. The originality is based on the the analysis of videos with discrete choice models as well as the explicit modeling of causal effects between the facial features and the recognition of the expression. Five models are proposed. The first assumes that only the last frame of the video triggers the choice of the expression. The second model has two components. The first captures the perception of the facial expression within each frame in the sequence, while the second determines which frame triggers the choice. The third model is an extension of the second model and assumes that the choice of the expression results from the average of perceptions within a group of frames. The fourth and fifth models integrate the panel effect inherent to the estimation data and are respectively extensing the first and second models. The models are estimated using videos from the Facial Expressions and Emotions Database (FEED). Labeling data on the videos has been obtained using an internet survey available at . The prediction capability of the models is studied in order to check their validity by cross-validation using the estimation data.
A Flow 3-D simulation is reported on the thermal phenomena that give rise to defects in LFC parts... more A Flow 3-D simulation is reported on the thermal phenomena that give rise to defects in LFC parts. In order to obtain a higher precision of the models, simple meshes and multiple blocks have been considered. Particularly, metal-foam heat transfer is used to calculate the lost foam volume and the rate of the filling process. High contraction points and defect concentration were obtained by means of the simulation of the solidification process, which facilitated the optimization of parameters at an industrial level, as well as the LFC production of hydrants.
The use of the rice hull is minimal in most of the Latin American countries and only a small port... more The use of the rice hull is minimal in most of the Latin American countries and only a small portion is used as fertilizer or fuel. However, products of rice hull obtained by pyrolysis can be useful for abrasive and refractory products based on silicon carbide (SiC). Recently some applications have been developed to use SiC as reinforcement for metallic alloys for metal matrix composites. This paper reports the synthesis of short fibers and small particles of SiC obtained by controlled combustion of rice hull. The SiC synthesis was performed in a gas furnace, designed during the research. This process was optimized by an experimental design which included as variables the temperature, pyrolysis time, the type of catalyst, and process atmosphere.
Este artículo revisa los materiales compuestos de matriz metálica (CCM) usados en las industrias ... more Este artículo revisa los materiales compuestos de matriz metálica (CCM) usados en las industrias eléctrica y electrónica. Usualmente, los composites útiles en estos sectores corresponden a la familia de las aleaciones ligeras, reforzadas con fibras o partículas. Por tal motivo, la revisión está enfocada en las aleaciones Al, Ti y Mg, sus propiedades y aplicaciones.
Mechanical, chemical and thermal properties of thermoset materials such as epoxy resins are condi... more Mechanical, chemical and thermal properties of thermoset materials such as epoxy resins are conditioned by cure schedule. There are different techniques to determine the resin conversion level during process such as Fourier-transform infrared spectroscopy (FTIR); in this study we analyze the curing of two comercial systems of DGEBA/DDM by this technique. The conversion level of epoxy groups was evaluated employing
A generation of new models has been proposed to handle some complex human behaviors. These models... more A generation of new models has been proposed to handle some complex human behaviors. These models account for the data ambiguity, and therefore extend the application field of the discrete choice modeling. The facial expression recognition (FER) is highly relevant in this context. We develop a dynamic facial expression recognition (DFER) framework based on discrete choice models (DCM). The DFER consists in modeling the choice of a person who has to label a video sequence representing a facial expression. The originality is based on the the analysis of videos with discrete choice models as well as the explicit modeling of causal effects between the facial features and the recognition of the expression. Five models are proposed. The first assumes that only the last frame of the video triggers the choice of the expression. The second model has two components. The first captures the perception of the facial expression within each frame in the sequence, while the second determines which frame triggers the choice. The third model is an extension of the second model and assumes that the choice of the expression results from the average of perceptions within a group of frames. The fourth and fifth models integrate the panel effect inherent to the estimation data and are respectively extensing the first and second models. The models are estimated using videos from the Facial Expressions and Emotions Database (FEED). Labeling data on the videos has been obtained using an internet survey available at . The prediction capability of the models is studied in order to check their validity by cross-validation using the estimation data.
A Flow 3-D simulation is reported on the thermal phenomena that give rise to defects in LFC parts... more A Flow 3-D simulation is reported on the thermal phenomena that give rise to defects in LFC parts. In order to obtain a higher precision of the models, simple meshes and multiple blocks have been considered. Particularly, metal-foam heat transfer is used to calculate the lost foam volume and the rate of the filling process. High contraction points and defect concentration were obtained by means of the simulation of the solidification process, which facilitated the optimization of parameters at an industrial level, as well as the LFC production of hydrants.
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Papers by Javier Cruz