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- Kinematics of a classical ballet base movement using a kinetic sensorPublication . Barbosa, Inês; Milho, João; Lourenço, Inês; Mota, Ana; Nascimento, Vanda Maria dos Santos; Carvalho, Alda; Carvalho, André; Portal, RicardoDance is an art form considered a language since it can sometimes reflect a population’s culture or even a celebration that accompanies humanity from its earliest times and which requires from performers a high physical and emotional dexterity. It is expected that the dancer performs rigorous and repetitive technical movements that often lead to painful injuries, resulting in 56% of classical ballet dancers will suffer from some type of musculoskeletal injury. Due to this high number of injuries, it is essential to study and analyse base movements for this type of dance in order to prevent injuries and to optimize the dancer's choreography and productivity. These movements are precedents of more complex movements. In this work, the study of a base dance movement, the Echappé Sauté, using biomechanical techniques is carried out to study the kinematics of the movement. For the data collection, three dancers voluntarily participated and the movements were capture using a 2nd Generation Kinect camera that allows the capture of 3D movement. The biomechanical analysis was performed using the IpiSoft software and a manual procedure was used to perform a 2D biomechanical analysis based on the assumption that the dance movements for this study occur only in one plane. The results were compared to show the adequacy of the use of the Kinetic sensor for 3D dance movement analysis. 7
- 3D printing of abdominal immobilization masks for therapeutics: dosimetric, mechanical and financial analysisPublication . Duarte, Jessica; Loja, M.A.R.; Portal, Ricardo; Vieira, Lina OliveiraMolding immobilization masks is a time-consuming process, strongly dependent on the healthcare professional, and potentially uncomfortable for the patient. Thus, an alternative sustainable automated production process is proposed for abdominal masks, using fused deposition modelling (FDM) 3D printing with polylactic acid (PLA). Radiological properties of PLA were evaluated by submitting a set of PLA plates to photon beam radiation, while estimations of their mechanical characteristics were assessed through numerical simulation. Based on the obtained results, the abdominal mask was 3D printed and process costs and times were analyzed. The plates revealed dose transmissions similar to the conventional mask at all energies, and mechanical deformation guarantees the required immobilization, with a 66% final cost reduction. PLA proved to be an excellent material for this purpose. Despite the increase in labour costs, a significant reduction in material costs is observed with the proposed process. However, the time results are not favorable, mainly due to the printing technique used in this study.
- Developments on finite element methods for medical image supported diagnosticsPublication . Almeida, Ana; Barbosa, Joaquim; Carvalho, André; Loja, Amélia; Portal, Ricardo; Rodrigues, José Alberto; Vieira, Lina OliveiraVariational image-processing models offer high-quality processing capabilities for imaging. They have been widely developed and used in the last two decades, enriching the fields of mathematics as well as information science. Mathematically, several tools are needed: energy optimization, regularization, partial differential equations, level set functions, and numerical algorithms. For this work we consider a second-order variational model for solving medical image problems. The aim is to obtain as far as possible fine features of the initial image and identify medical pathologies. The approach consists of constructing a regularized functional and to locally analyse the obtained solution. Some parameters selection is performed at the discrete level in the framework of the finite element method. We present several numerical simulations to test the efficiency of the proposed approach.
- Análise biomecânica de movimento de ballet usando um sensor KineticPublication . Lourenço, Inês; Barbosa, Inês; Milho, João; Mota, Ana; Nascimento, Vanda; Carvalho, Alda; Carvalho, André; Portal, RicardoA dança é uma forma de arte considerada como uma forma de linguagem uma vez que pode refletir por vezes uma cultura de uma população ou até uma celebração que acompanha a humanidade desde os seus mais remotos tempos [1] e que requer do bailarino uma destreza física e emocional exigente. Dentro das capacidades físicas, é esperado do bailarino movimentos técnicos realizados de forma rigorosa e repetitiva que levam muitas vezes a lesões dolorosas para os mesmos, admitindo-se que 56% das bailarinas praticantes de Ballet clássico irão sofrer de algum tipo de lesão musculoesquelética [2].
- Characterization of a dance movement using a Kinetic cameraPublication . Barbosa, Inês; Milho, João; Lourenço, Inês M.; Mota, Ana; Nascimento, Vanda S.; Carvalho, André; Portal, Ricardo; Carvalho, AldaDance is an art form considered as a form of language since it can sometimes reflect a culture of a population or even a celebration that accompanies humanity from its earliest times and which requires of the dancer a high physical and emotional dexterity. However, it is expected that the dancer performs rigorous and repetitive technical movements that often lead to painful injuries. Due to the high number of injuries, it is essential to study and analyze base movements for this type of dance in order to prevent injuries and to optimize the dancer's choreography and productivity. These movements are precedents of more complex movements. In this work, the study of a basic jump, the Grand Jete, using biomechanical techniques is carried out by finding the kinematics of the movement. For the data collection, three dancers (2 females and 1 male) voluntarily participated and the movements were capture using a 2nd Generation Kinect camera that allows the capture of 3D movement. The biomechanical analysis was performed for the movement recorded and the results were presented to show the adequacy of the methodology proposed. By using this methodology, the aim is to characterize the movement and to be able to promote a better understanding of everything involved in the performance of the movement with the performers and teachers.
- A usability study on widget design for selecting boolean operationsPublication . Chambel Lopes, Diogo; Mendes, Helena; Portal, Ricardo; Klerk, Rui de; Nogueira, Isabel; Lopes, DanielApplying the correct set of Boolean operations is a fundamental task in constructive solid geometry (CSG), which is a staple in automated manufacturing systems. Although textual buttons and icons are the most common interfaces to apply such operations, these require an unnecessary cognitive load that hampers the solid modeling process. This study presents VennPad, a novel CSG widget that gathers all Boolean operations under the same user interface control element and is represented as a two-set Venn diagram. Contrary to conventional CSG widgets, VennPad supports a graphical interface that gives simultaneous access to several types of Boolean operations (intersection, union, difference, symmetric difference and split). A usability study was conducted to ascertain whether VennPad is a more natural interface compared to textual buttons and icon-based widgets for different solid modeling tasks. VennPad proved to be an effective interface to perform Boolean operations. Qualitative feedback places VennPad as the preferred interface, but efficiency results are operation dependent, thus, opening the way to new design iterations.
- Biomechanics of a pedestrian accident reconstructionPublication . Portal, Ricardo; Dias, J. Pereira; Sousa, Luís G.Pedestrians represent about 20% of the overall fatalities in Europe's road traffic accidents, as well as in Portugal. An in-depth investigation, accident reconstruction, is mandatory in order to analyze with care fundamental aspects of an accident. Detailed information about the injuries and injury causation mechanisms are with great use for it. Accident reconstruction computational techniques using pedestrian biomechanical models are used to evaluate the accident conditions that lead to major pedestrian injuries, such as the vehicle's speed and the impact location. For biomechanical injury criterions, the AIS (Abbreviated Injury Scale), the HIC (Head Injury Criterion) and some other injury criterions are used. Pedestrian's height, weight, gender, age, vehicle geometry (or category) and travelling speed, significantly influence the pedestrian injuries in the event of a road collision. The use of injury scales and biomechanical criterions in the in-depth accident investigation of road accidents, such as AIS, can improve significantly the quality of the reconstruction process. The computer simulation of vehicle-to-pedestrian collisions is fundamental for the study of the dynamics of these road accidents. Where did the pedestrian is when the vehicle hits him? Normally, there is no simple and clear answer. The pedestrian, if survives, states that he uses the crossway, the driver of the vehicle states otherwise, that the location of the pedestrian was much later than the pedestrian crossing. This work presents an accident where only the use of accident reconstruction specialized software, PC-Crash, conjugated with all available information allowed the determination of the vehicle's speed and the Location of the pedestrian.
- Development and validation of SuperDEM for non-spherical particulate systems using a superquadric particle methodPublication . Gao, Xi; Yu, Jia; Portal, Ricardo; Dietiker, Jean-Francois; Shahnam, Mehrdad; Rogers, William A.This article presents the development and validation of the Superquadric Discrete Element Method (SuperDEM) for non-spherical particle simulation using a superquadric particle method in open-source CFD suite MFiX. A superquadric particle-particle contact algorithm with accelerating and stabilizing strategy was developed. A superquadric particle-arbitrary wall contact algorithm was developed, which enables the simulation in complex geometry. The solver was validated by comparing with experimental data generated in this study or available in the literature. Tests include cylinder contacting with a wall, static packing of M&M chocolate candies in a cylindrical container, static packing of cylinders in a cylin-drical container, dynamic angle of repose of cylinders in a rotating drum, and discharging of chocolate candies from a hopper. Besides, MPI parallelization of the solver was implemented and the parallel per-formance of the solver using MPI was assessed through large-scale simulations of 1 million, 10 million, and 100 million particles on up to 6800 cores, which demonstrates that the SuperDEM solver has great potential for industrial-scale systems simulation. (c) 2021 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences.
- Finite element techniques for medical image processingPublication . Almeida, A.; Barbosa, Joaquim; Carvalho, A.; Loja, Amélia; Portal, Ricardo; Rodrigues, José Alberto; Vieira, L.We consider some second-order variational model for solving medical image problems. The aim is to obtain as far as possible fine features of the initial image and identify medical pathologies. The approach consists of constructing a family of regularized functionals and to select locally and adaptively the regularization parameters. The parameters selection is performed at the discrete level in the framework of the finite element method. We present several numerical simulations to test the efficiency of the proposed approach.