CDRsp - Comunicações em conferências internacionais
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- Optimization of Scaffolds in Alginate for Biofabrication by Genetic AlgorithmsPublication . Rezende, Rodrigo; Rezende, Mylene; Bártolo, Paulo; Mendes, Ausenda; Filho, Rubens Maciel; Bartolo, Paulo; Mendes, AusendaWith an increasing in the rate of transplants due to damaged or affected tissues or organs by accidents or diseases and also by the aging of the population in many countries as Brazil, have motivated the research of some novel and alternative ways focused on restoring and replacing tissues. Biofabrication by means of Rapid Prototyping techniques can help in the fashioning and final production of scaffolds devoted to support and stimulate the growth of new tissues. For soft tissues, a biomaterial known as Alginate has been studied and used as raw-material for scaffolds fabrication. A scaffold must guarantee good strength and stiffness at the same time the material degrades gradually. In this work, a single mathematical model experimentally obtained that describes an interesting mechanical behavior of the degradation of alginated-scaffolds is developed. The optimization process scheme using Genetic Algorithms to maximize the elastic modulus and therefore to aid the design of scaffolds in alginate is proposed. The optimization is very welcome to tissue engineering and Biofabrication.
- Quantification and Modulation of Tremor in Rapid Upper Limb MovementsPublication . Faria, Paula; Leal, Adriana; Freire, António; Januário, Cristina; Patrício, Miguel; Castelo-Branco, MiguelTremor is a manifestation of a variety of human neurodegenerative diseases, notably Parkinson’s disease (PD), a chronic disease that affects one in 100 people over age 60 years. Recent research indicates that more than five million worldwide have PD. This disease is primarily caused by a progressive loss of dopamine neurons in the nigrostriatal system that leads to widespread motor symptoms such as bradykinesia, rigidity, tremor and postural instability. Although the diagnosis of PD remains clinical, advances in functional and structural imaging have improved the ability to differentiate between PD and Essential Tremor (ET), as well as between different akinetic-rigid syndromes. No definitive test or biomarker is available for PD, so the rate of misdiagnosis is relatively high. It is therefore crucial to be able to characterize tremor in PD and ET as it is a very common feature at the onset of both diseases. This is made possible with a combination of a neuroscientific and methodological multi-modal imaging approaches, namely kinetic recording methods using accelerometers to quantify tremor amplitude and frequency and functional magnetic resonance imaging (fMRI). These allow the identification of the neural underpinnings of tremor in both PD and ET patients, which in fact have been surprisingly difficult to decipher. In this work we aim to find which tasks involving upper limb movements are suitable to modulate both PD and ET tremor. The same tasks are considered with and without added loading. The resulting analysis will allow designing an efficient fMRI protocol aiming at the identification of the cortical circuits responsible for the modulation of tremor.
- Numerical Calculations in Tissue EngineeringPublication . Almeida, Henrique de Amorim; Bártolo, Paulo J.The design of optimized scaffolds for tissue engineering is a key topic of research, as the complex macro- and micro- architectures required for a scaffold depends not only on the mechanical properties, but also on the physical and molecular queues of the surrounding tissue within the defect site. Thus, the prediction of optimal features for tissue engineering scaffolds is very important for its mechanical, vascular or topological properties. The relationship between high scaffold porosity and high mechanical properties is contradictory, as it becomes even more complex due to the scaffold degradation process. A scaffold design strategy was developed, based on the finite element method, to optimise the scaffold design regarding the mechanical and vascular properties as a function of porosity. Scaffolds can be considered as a LEGO structure formed by an association of small elementary units or blocks. In this research work, two types of family elementary scaffold units were considered: non-triple periodic minimal surfaces and triple periodic minimal surfaces that describe natural existing surfaces. The main objective of this work is to present the undergoing research based on numerical simulations for the evaluation and prediction of the scaffold's behaviour under structural and vascular loading, and its topological optimisation.
- Further remarks on the "Smith is Huq" conditionPublication . Martins-Ferreira, Nelson; Van der Linden, TimWe compare the Smith is Huq condition (SH) with three commutator conditions in semi-abelian categories: first an apparently weaker condition which arose in joint work with Bourn and turns out to be equivalent with (SH), then an apparently equivalent condition which takes commutation of non-normal subobjects into account and turns out to be stronger than (SH). This leads to the even stronger condition that weighted commutators in the sense of Gran, Janelidze and Ursini are independent of the chosen weight, which is known to be false for groups but turns out to be true in any two-nilpotent semi-abelian category.
- A eficiência da materialidade - O recurso a ferramentas digitais de simulação e fabricação aditiva na procura de uma maior eficácia dos dispositivosPublication . Gonçalves, Sérgio; Mateus, João Vasco; Hernandis-Ortuño, BernabéA praxis do Design de produtos, condicionada pelas crises sociais e ambientais que o mundo atravessa, deve passar pela procura de uma cada vez maior eficiência dos objetos na sua dimensão ambiental. Embora esta questão esteja a jusante de questões eventualmente mais relevantes na minimização deste problema, e que têm a ver com a legitimação da própria existência dos dispositivos, a otimização do recurso a matérias primas no fabrico de objetos é de fulcral importância. A possibilidade de otimizar os produtos pela redução da incorporação de matéria prima no seu fabrico e adequar o material a uma determinada utilização é central no seu processo de desenvolvimento. Por outro lado, as novas possibilidades trazidas pela fabricação aditiva no sentido de reduzir a quantidade de materiais e processos industriais associados à produção de componentes técnicos complexos permite perspetivar uma melhoria significativa do impacto ambiental tradicionalmente associado à sua obtenção. O presente artigo procura examinar como as tecnologias digitais de análise, otimização e fabricação aditiva poderão constituir uma resposta viável para uma produção mais eficiente do ponto de vista da incorporação de recursos não-renováveis e da minimização do impacto ambiental associado às tecnologias de produção tradicionais.
- Optimization of a Wood Plastic Composite to Produce a New Dynamic Shading SystemPublication . Martins, G.; Antunes, F.; Mateus, Artur; S. Baptista; C. MalçaThe shading systems of the windows may play a protagonist role in the reduction of energy consumption in lighting, artificial ventilation and air conditioning, contributing to sustainable development regarding bioclimatic architecture and improvement of the energetic efficiency in buildings. This work, resulting from a partnership between architecture and materials science, reports the development of an innovative and dynamic shading system that simultaneously fulfils various aesthetic, functional and environmental requirements. The original design of the system, derived from this collaboration, enables an industrial low cost production in virtue of the selection of technologies and materials concurrently adequate to multiple objectives. This work also aims at contributing to a sustainable construction through the use of eco-friendly materials such as biocomposites produced from recyclable polymers and vegetable fibres, using extrusion as processing technology both for blending the raw materials and for the shutter units production. The optimization of materials for this specific application involved wood plastic composites (WPC) based on high density polyethylene (HDPE), industrial residues of pine sawdust and additives such as coupling agents, pigments and UV protectors. Results showed that the optimized WPC made from recycled industrial pine wood residues presents thermal stability, mechanical strength and water absorption appropriate to be applied in the production of the new architectural solutions such as the innovative shading system presented.
- DLL architecture for OFDM based VLC transceivers in FPGAPublication . Duarte, Luis; Rodrigues, Luis; Alves, Luis N.; Ribeiro, Carlos; Figueiredo, MónicaThis paper addresses the problem of achieving high bandwidth in a DLL design for OFDM based VLC broadcast systems. It describes the implementation of efficient Data Link Layer (DLL) and Forward Error Correction (FEC) modules in a Xilinx FPGA. The proposed DLL aims at furnishing the adequate means to fragment and route both high data-rate (HDR) and moderate data-rate (MDR) service requests while maintaining a continuous transmission flow. The FEC modules aims at providing sufficient error correction capabilities with reasonable computation overheads. Another goal was to develop these modules under a globally asynchronous locally synchronous paradigm, ensuring high modularity and performance.
- Study on the aerodynamic behavior of a UAV with an applied seeder for agricultural practicesPublication . Felismina, Raimundo; Reis Silva, Miguel; Mateus, Artur; Malça , CândidaIt is irrefutable that the use of Unmanned Airborne Vehicle Systems (UAVs) in agricultural tasks and on the analysis of health and vegetative conditions represents a powerful tool in modern agriculture. To contribute to the growth of the agriculture economic sector a seeder to be coupled to any type of UAV was previously developed and designed by the authors. This seeder allows for the deposition of seeds with positional accuracy, i.e., seeds are accurately deposited at pre-established distances between plants [1]. This work aims at analyzing the aerodynamic behavior of UAV/Seeder assembly to determine the suitable inclination - among 0°, 15° and 30° - for its takeoff and for its motion during the seeding operation and, in turn, to define the suitable flight plan that increases the batteries autonomy. For this the ANSYS® FLUENT computational tool was used to simulate a wind tunnel which has as principle the Navier-Stokes differential equations, that designates the fluid flow around the UAV/Seeder assembly. The aerodynamic results demonstrated that for take-off the UAV inclination of 30° is the aerodynamically most favorable position due to the lower aerodynamic drag during the climb. Concerning flying motion during the seeding procedure the UAV inclination of 0° is that which leads to lower UAV/Seeder frontal area and drag coefficient.
- Comparison by computer fluid dynamics of the drag force acting upon two helmets for wheelchair racersPublication . Forte, P; Marinho, D. A.; Morouço, P; Pascoal-Faria, P.; Barbosa, T. M.The aim of this study was to compare the drag force created by two helmets (time trial and road)used by a wheelchair racer. The head and helmet of the racer were scanned to obtain the3D models. Numerical simulation was run on Fluent, having as output the drag force for both helmets (road and time trial) in two different positions (0º and 90º) and increasing velocities (from 2.0 to 6.5 m/s). The greatest aerodynamic drag was noted wearing a time trial helmet in 90º ranging from 0.1025N to 0.8475N; this was also the position with the highest drag. The velocity with higher drag for booth helmets was at 6.5 m/s. The time trial helmet at 0º had the lower aerodynamic drag, compared with the same position of road helmet. The drag force seems to be lower wearing the time trial helmet and keeping the 0º position and, thus, should be considered for sprinting events.
- A finite element method to study multimaterial wind towersPublication . Pascoal-Faria, P.; Dias, C.; Oliveira, M; Alves, N.Wind towers are used to produce electrical energy from the wind. A significant number of towers is manufactured using tubular separately steel or concrete, having limitations such as maximum diameter and height imposed essentially by transportation limitations. Developed computational studies on structural design of towers have been mainly focused on a single material. This investigation aims to develop a finite element method able to study structural design of wind towers combining different materials. The finite element model combines solid and shell elements encompassing different geometries. Several case studies are considered to validate the proposed method and accurate results are obtained.