a b s t r a c tIn order to improve its tribocorrosion resistance, nanotubular structures were produced on Ti6Al4V surfaces by anodic treatment in a mixture of 1 M H 2 SO 4 and 0.08 M HF electrolyte. Tribocorrosion tests were performed in a phosphate-buffered saline solution (PBS) against an alumina ball under 50 mN. Results showed that nanostructured surfaces exhibited significantly lower tendency to corrosion due to the protecting effect given by the well-adherent TiO 2 nanotubular layer.
The use of computer simulation to actually predict the thermal response of human body in different environments has becoming more important in a way that comfort, or thermal comfort in particular, has been identified as a factor of productivity and performance. In this work, sensitivity studies on a transient thermal model of the human body, previously used to investigate thermal comfort in different fields, are presented. The computational model combines a thermoregulation model of the human body and a model describing the dynamic heat and moisture transfer through clothing. The environment parameters are very important factors related to indoor climatic conditions and consequent comfort sensation. Changes in ambient and radiant temperatures, as well as, in convective and radiant coefficients, are analyzed specially in terms of skin temperature of the human body. The results show that the convection mechanism is dominant over radiation and the mass associated with a specific part of the body, influences the temperature variations. The simulated results and conclusions allow further investigation on the validity of combining this thermal model with CFD models to simulate ventilation, in order to predict thermal comfort indexes for different environments.
In the context of Shared Autonomous Vehicles, the need to monitor the environment inside the car will be crucial. This article focuses on the application of deep learning algorithms to present a fusion monitoring solution which was three different algorithms: a violent action detection system, which recognizes violent behaviors between passengers, a violent object detection system, and a lost items detection system. Public datasets were used for object detection algorithms (COCO and TAO) to train state-of-the-art algorithms such as YOLOv5. For violent action detection, the MoLa InCar dataset was used to train on state-of-the-art algorithms such as I3D, R(2+1)D, SlowFast, TSN, and TSM. Finally, an embedded automotive solution was used to demonstrate that both methods are running in real-time.
Organs-on-a-chip, OoC, have been extremely important to reduce the use of animal models allowing researchers to conduct accurate in vitro experiments with high throughput. Year after year, increasingly complex OoC platforms have been developed to better recapitulate the in vivo environment, and numerical simulations have played a fundamental role in this process. Numerical simulations in health sciences research are constantly evolving and have allowed researchers not only to better understand but also to complement and improve the in vitro experiments. Aiming to evaluate the influence of geometry on fluid flow, in the present work, three different geometries of a single organ-on-a-chip were created, and numerical simulations were conducted by using Ansys® Fluent software. The fluid flow of the culture medium with dissolved oxygen was simulated. In terms of oxygen consumption, the influence of the geometry was noticeable in the organoid region. In terms of velocity fields, the results were not significantly affected by the geometry.
Cancer continues to be one of the diseases that most affect the population around the world and different lines of research have been conducted to develop new therapies. However, a critical problem in this process is the lack of suitable in vitro preclinical platforms to assess the drug targets, toxicity, and efficacy. In order to surpass these issues, organ-on-a-chip (OoC) platforms emerged as a potential alternative for two-dimensional in vitro models, and computational simulations have played an important role. This tool boosts and supports the development process of OoC devices. Moreover, through numerical simulations, an overview of the fluid flow can be obtained which is useful for getting insights about the expected experimental results. Nevertheless, attention must be taken when defining the boundary conditions, fluid properties, and solution methods among other parameters that will affect the end results. In this regard, the aim of the present work is to evaluate the influence of varying the boundary conditions on the oxygen gradients along the liver-on-a-chip, namely imposing different velocities at the inlet and considering or not the convective term. It was found that for the OoC tested, by increasing the inlet velocity, the dissolved oxygen that reaches the organoids decreases.
In the present work, a numerical model was developed to simulate the placement of a pin through-hole (PTH) component in an aperture containing solder paste by using Ansys Fluent® software. The work uses numerical tools to understand the physical process and the solder paste behaviour for future manufacturing improvements. The component movement was simulated with the dynamic mesh model through a user-defined function (UDF). Due to software limitations, the pin of the component is already contacting the solder paste at the start of the movement. additionally, the contact detection feature was activated to prevent the pin and PCB contact during the solder paste melting. Nevertheless, the component can still move in the domain if other forces act upon it, except in the direction where the contact would occur. The second point to address is the meniscus formation process. This begins with the evaporation of the solder paste flux, causing a volume reduction followed by the melting of the metallic beads. The simulation allowed us to see that the melted solder surrounded the pin through capillarity and reproduced the phenomena of this solder printing process. This work allowed to follow the behaviour of both the component and the solder paste.
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