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Reliability: A Neglected Topic in the Power Electronics Curricula
Calleja, Hugo,Chan, Freddy The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6
This paper presents the approach followed to develop a course that introduces reliability into the design of power electronics converters. The course is part of the curriculum of a master of science in electrical engineering program, and it is aimed at providing reliability tools that can be used in a straightforward manner, while avoiding the mathematical intricacies. The reliability calculations are performed according to the Military Handbook 217, using the evaluation version of a commercial software package which greatly reduces the computational burden usually associated with this task. The course assessment shows that, after attending the course, students were able to improve the mean time between failures in a power-electronics converter, from a minimum of 5%, up to 100%.
Flow Diverter Treatment for Non-Ruptured Carotid Aneurysms: Efficacy and Safety
López-Callejas Orlando,Ortiz-Giraldo Andres F,Vera Daniela D,Ramirez-Rojas Diego A,Villamizar-Barahona Ana B,Ferreira-Prada Carlos A.,Galvis Melquizidel,Vargas-Pérez Oliverio,Serrano-Gómez Sergio,Reye 대한신경중재치료의학회 2023 Neurointervention Vol.18 No.1
Purpose: Internal carotid artery (ICA) aneurysm treatment with a flow diverter (FD) has shown an adequate efficacy and safety profile, presenting high complete occlusion or near occlusion rates with low complications during follow-up. The purpose of this study was to evaluate the efficacy and safety of FD treatment in non-ruptured internal carotid aneurysms.Materials and Methods: This is a retrospective, single-center, observational study evaluating patients diagnosed with unruptured ICA aneurysms treated with an FD between January 1, 2014, and January 1, 2020. We analyzed an anonymized database. The primary effectiveness endpoint was complete occlusion (O’Kelly–Marotta D, OKM-D) of the target aneurysm through 1-year follow-up. The safety endpoint was the evaluation of modified Rankin Scale (mRS) 90 days after treatment, considering a favorable outcome an mRS 0-2.Results: A total of 106 patients were treated with an FD, 91.5% were women; the mean follow- up was 427.2±144.8 days. Technical success was achieved in 105 cases (99.1%). All patients included had 1-year follow-up digital subtraction angiography control; 78 patients (73.6%) completed the primary efficacy endpoint by achieving total occlusion (OKM-D). Giant aneurysms had a higher risk of not achieving complete occlusion (risk ratio, 3.07; 95% confidence interval, 1.70 - 5.54]). The safety endpoint of mRS 0-2 at 90 days was accomplished in 103 patients (97.2%).Conclusion: Treatment of unruptured ICA aneurysms with an FD showed high 1-year total occlusion results, with very low morbidity and mortality complications.
Gutiérrez-Calleja Ramón A.,Rodríguez-Cortés Octavio,Flores-Mejía Raúl,Muñoz-Diosdado Alejandro 대한독성 유전단백체 학회 2021 Molecular & cellular toxicology Vol.17 No.4
Background Gold nanoparticles (AuNPs) have potential for a wide range of applications as therapeutic and diagnostic agents. Since they have a high probability of interacting with human immune cells, cytotoxicity studies must be conducted. The investigation of AuNP/immune cell interaction has mainly focused on macrophages and dendritic cells, along with some other cell lineages. Scarce information is available regarding the effect of AuNPs on mast cells, which are abundant in the skin, mucosa, and perivascular space. Objective To examine the uptake of AuNPs by HMC-1 human mast cells and the resulting effect on cell viability, pro-inflammatory mediators production, and proliferation. Results With AuNPs treatment, the viability of HMC-1 cells decreased slightly (never less than 95%) during the first 4 h, but no changes were detected in the proliferation rate at any time. Increasing concentrations of AuNPs produced greater cell granularity (uptake). CLSM images exhibited AuNPs clusters in the cell cytoplasm. TNF-α and ROS production was not stimulated by AuNPs treatment at any concentration/time. Conclusion Internalization of AuNPs into HMC-1 cells was demonstrated in an in vitro model, without showing cytotoxic effects or induction of pro-inflammatory mediators at any concentration tested. Background Gold nanoparticles (AuNPs) have potential for a wide range of applications as therapeutic and diagnostic agents. Since they have a high probability of interacting with human immune cells, cytotoxicity studies must be conducted. The investigation of AuNP/immune cell interaction has mainly focused on macrophages and dendritic cells, along with some other cell lineages. Scarce information is available regarding the effect of AuNPs on mast cells, which are abundant in the skin, mucosa, and perivascular space. Objective To examine the uptake of AuNPs by HMC-1 human mast cells and the resulting effect on cell viability, pro-inflammatory mediators production, and proliferation. Results With AuNPs treatment, the viability of HMC-1 cells decreased slightly (never less than 95%) during the first 4 h, but no changes were detected in the proliferation rate at any time. Increasing concentrations of AuNPs produced greater cell granularity (uptake). CLSM images exhibited AuNPs clusters in the cell cytoplasm. TNF-α and ROS production was not stimulated by AuNPs treatment at any concentration/time. Conclusion Internalization of AuNPs into HMC-1 cells was demonstrated in an in vitro model, without showing cytotoxic effects or induction of pro-inflammatory mediators at any concentration tested.
Reliability: A Neglected Topic in the Power Electronics Curricula
Hugo Calleja,Freddy Chan 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6
This paper presents the approach followed to develop a course that introduces reliability into the design of power electronics converters. The course is part of the curriculum of a master of science in electrical engineering program, and it is aimed at providing reliability tools that can be used in a straightforward manner, while avoiding the mathematical intricacies. The reliability calculations are performed according to the Military Handbook 217, using the evaluation version of a commercial software package which greatly reduces the computational burden usually associated with this task. The course assessment shows that, after attending the course, students were able to improve the mean time between failures in a power-electronics converter, from a minimum of 5%, up to 100%.
Ivan Sanchez-Calleja,Alberto Martínez-Gutierrez,Ruben Ferrero-Guillén,Javier Díez-Gonzalez,Hilde Perez 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.2
The advent of smart manufacturing (SM) has led to the creation of collaborative environments with cyber-physical systems (CPS) that generate added value. However, the performance of combined industrial operations between mobile CPS such as autonomous mobile robots (AMRs) and collaborative robots (cobots) is hampered by the high uncertainty between their relative spatial locations and the existence of heterogeneous communication protocols that create a barrier to their integration into production processes. For this reason, a novel contact system method (CSM) is proposed to determine the position of the AMR without the need for any additional hardware making use of an architecture that facilitates efficient communication between AMRs and cobots. For this purpose, a mathematical model has been defined to characterize the position of a spatial object with six degrees of freedom in order to calculate the deviation between the AMR and the cobot base. The proposed method has also been evaluated by quantifying the position and orientation error before and after applying the CSM. The effectiveness of the CSM method has been assessed in a real application case based on the feasibility of performing an assembly operation between a bearing and different shafts. The results show a significant improvement of 96.2% in positional accuracy and 85.4% in orientation compared to AMR accuracy. In addition, a 92.5% success rate was achieved in the assembly operation analyzed between a bearing and a shaft of the same diameter. Furthermore, the proposed architecture has enabled the coordination between the cobot and the AMR by automating the processes. Therefore, this work contributes to the field of SM by proposing a practical solution to the challenges of generating added value through the creation of collaborative environments with CPS.
A Cleaner Milling Process Replacing Emulsion Coolant by Cryogenics CO2
Octavio M. Pereira Neto,Calleja‑Ochoa,I. Ayesta,A. Rodríguez,H. González‑Barrio,L. N. López de Lacalle 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.1
In manufacturing sector, looking for a balance between environmental and technical efficiency taking into account productivity is mandatory. Some sectors, such as the biomedical manufacturing sector, also needs to consider the cleanness inherent to prosthesis manufacturing processes for avoiding pathogens transfer to the human body, that is, neither chemicals, bacteria, nor uncontrolled metals can be introduced during the surgical intervention. This work here presented stems from the idea of analyzing the cleanness of cryogenic cooling to be applied to medical pieces. For this, several samples were machined using CO2 cryogenic technology and oil emulsions, respectively. In particular, a modified milling tool was used to apply not only efficiently as cutting fluid but also as cleaner fluid. Afterwards, they were analyzed by Scanning Electron Microscope (SEM) with the aim of looking for biological remains. Finally, with the aim of validating the modified tool in which CO2 is introduced axially as internal coolant, its tool life was tested in comparison with a conventional one. The results shown that the use of CO2 as internal coolant significantly improves the cleanness of current machining processes in comparison with the use of oil emulsions and the way in which is injected does not affect to machining performance.