C-MAST - Center for Mechanical and Aerospace Science and Technologies
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Historically, the research unit “CAST – Centre for Aerospace Science and Technologies” was created in 1994 by a small group of aerospace engineers. Now we became a Reasearch Center developing studies in Energy, Mechanical and Aerospace Engineering with a wide spectrum of areas, from Astrodynamics to Technological Forecasting.
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- 3D and transient numerical modeling of door opening and closing processes and its influence on thermal performance of cold roomsPublication . Carneiro, Rui; Gaspar, Pedro Dinis; Silva, Pedro Dinho daThis paper presents the comparison of three-dimensional and transient CFD modelling of the opening and closing processes of hinged and sliding doors and its influence on the thermal performance of cold rooms. A species transport model is used to model a tracer gas. The air infiltration through the door opening is determined by the tracer gas concentration decay technique. The prediction of air temperature and velocity fields in the cold room as function of external air temperature allows quantifying the increase of the air infiltration rate and consequently of the average air temperature inside the cold room. When the hinged door is used, the formation of vortices during the opening movement promotes a larger and faster thermal interaction between the two contiguous air masses. The air infiltration during the sliding door opening/closing is 20% lower than for a hinged door. Consequently, the average air temperature inside the cold room is 17% lower. The air infiltration rate was numerically predicted and compared with analytical models’ results. The numerical model predicts closely the air infiltration rate for each door type. Moreover, the transient CFD modelling extends the results of the analytical models allowing the analysis of the influence of door opening and closing processes on the air temperature and velocity fields.
- 3D Printed Robotic Hand with Piezoresistive Touch CapabilityPublication . Fonseca, Gonçalo; Nunes-Pereira, J.; Silva, AbilioThis work proposes the design of a low-cost sensory glove system that complements the operation of a 3D-printed mechanical hand prosthesis, providing it with the ability to detect touch, locate it and even measure the intensity of associated forces. Firstly, the production of the prosthetic model was performed using 3D printing, which allowed for quick and cheap production of a robotic hand with the implementation of a mechanical system that allows controlled movements with high performance and with the possibility of easily replacing each piece individually. Secondly, we performed the construction and instrumentation of a complementary sensory mimicry add-on system, focusing on the ability to sense touch as the primary target. Using piezoresistive sensors attached to the palm of the glove, a multi-sensor system was developed that was able to locate and quantify forces exerted on the glove. This system showed promising results and could be used as a springboard to develop a more complex and multifunctional system in the future.
- 3D transient CFD modeling of sliding door operation and its influence on the thermal performance of cold roomsPublication . Carneiro, Rui; Gaspar, Pedro Dinis; Silva, Pedro Dinho daThe need of rationalize energy consumption in agrifood industry has fasten the development of methodologies to improve the thermal and energy performances of cold rooms. This paper presents a 3D transient Computational Fluid Dynamics (CFD) modelling of a cold room to evaluate the air infiltration rate through sliding doors. A species transport model is used for modelling the tracer concentration decay technique. Numerical predictions indicate that air temperature difference between spaces affects the air infiltration. For this case study, the infiltration rate increases 0.012 m3 s-1 per K of air temperature difference. The knowledge about the evolution of air infiltration during door opening/closing times allows to draw some conclusions about its influence on the air conditions inside the cold room, as well as to suggest best practices and simple technical improvements that can minimize air infiltration, and consequently improve thermal performance and energy consumption rationalization.
- Acquisition of multiple physiological parameters during physical exercisePublication . Felizardo, Virginie; Gaspar, Pedro Dinis; Garcia, Nuno M.; Reis, VMThis paper describes the experimental method focused on the acquisition of various physiological parameters during different effort levels of physical exercise like walking and running at several velocities. The study involved 57 young and adult people, 43 male and 14 female (24,37±5,96 years), from which 48 were soldiers belonging to the Infantry Regiment n.° 13 (RI13) of the Portuguese Army and 9 were teachers or college students of Sport Sciences, physically active but not competitive. The experimental measures provide a set of information that offers insight about the health status and physical performance of the subjects during exercise. This experimental method procedure is suited for the acquisition of physiological parameters with both the wireless physiological data acquisition systems such as the bioPlux and the respiratory analyzer gas systems such as Cosmed K4b2.The data was collected to allow the definition of a model that will be used to estimate the energy expenditure of a subject using a wireless physiological data acquisition system, which is much more comfortable and suitable to monitor physical exercise in everyday use than the standard method that makes use of a respiratory gas analysis system.
- Active and intelligent packaging - Principles of operation, characteristics and applicationsPublication . Rato, Nuno; Gaspar, Pedro DinisFood preservation is a topic increasingly being discussed due to market needs, where food from all over the world is required under the best chemical and physical conditions, with minimal waste. Active packaging is defined as the deliberate addition of some components to enhance the properties of the packaging. The various types of active packaging are oxygen scavengers, carbon dioxide emitters and absorbers, ethylene absorbers, ethanol emitters, moisture absorbers, and antimicrobial agents. Smart packaging includes indicators that provide information on product quality and safety over time, such as packaging history, inside and outside atmosphere, oxygen levels, among others. Given the demands on food safety and quality as well as product traceability, there is an exponential increase in the development, production and use of active and intelligent packaging.
- Active Learning “Factory of Boxes” in the Teaching-Learning Processes in Engineering and EntrepreneurshipPublication . Silva, Ricardo; Garcez, Ana; Gomes, Maria; Morais, António; Lima, Tânia M.; Santos, Fernando Charrua; Franco, Mário"Factory of Boxes” is an Active Learning (AL) where concepts related to Industrial Engineering, Mechanics, Mechatronics, Electrotechnics and Entrepreneurial Management can be cultivated. The interconnection of these concepts offers the possibility of developing occupational related skills in the most diverse areas of knowledge. It is the use of AL, simulating the method of a factory which produces cardboard boxes in different layouts and production systems, namely: (a) Classic Taylorist-Fordist Model; (b) Positions’ Enrichment Volvo Model; (c) cell production Toyota Model; and (d) automated line Taylorist-Fordist Classic Model. Data collection was based on observation, counting and recording production in a simulated test at two Universities (UFPB – Brazil and UBI – Portugal) involving master students in Industrial Engineering. The data were analysed from the aspects of productivity and cycle-time. The results showed: (a) It is an economically viable AL since it uses low-cost materials (except for simulating with automated posts which requires some investment) and (b) the Classic Model has the highest cycle-time and the Toyota Model has higher productivity, although these results derive from simulations with a teaching-learning aim and cannot be generalized. With the involvement of students-apprentices, knowledge was absorbed through layout-sharing and analysis of work organisation models’ dynamics, involving activities using Engineering, Industrial Management and Entrepreneurship tools and concepts.
- Advanced CaZrO3-MgO Ceramic Compositions for High Responsability ApplicationsPublication . Nunes-Pereira, J.; Pereira Silva, A; Pena, Pilar; Baudin, CarmenThe development of new advanced materials for harsh environment operation conditions, such as high temperature, wear and severe erosion and corrosion, is of growing interest, namely for transport and energy industries, due to the ecological and energetic current concerns on a global scale. Particularly, in aerospace industry the increase of working temperature of engines and turbines combined with weight reduction will give rise to higher thrust and lower fuel consumption and consequently less emissions. [...]
- Airflow and Thermal Behavior within Peaches Packaging Box Using Computational Fluid Dynamics - A Preliminary StudyPublication . Ilangovan, Adhiyaman; Silva, Pedro D.; Gaspar, Pedro DinisPost-harvest cold storage of peaches is an essential element to maintain the quality of the fruits without any loss. This work aims to present a CFD model, to predict airflow patterns and temperature profiles in ventilated packaging systems, during the forced-air cooling of Peaches stored in a cold chamber. Transient CFD simulations are performed for the chamber containing four ventilated boxes and the evaluation of the results show that the temperature removal near the vent holes and the hand holes is relatively high when compared to other regions of the packaging box. This preliminary study reveals the airflow behavior develop an uneven temperature distribution within the box. To overcome the flaws, future work is focused on modifying the vent hole design to improve the airflow phenomenon to maintain the temperature homogeneity throughout the box.
- Ajustamento e Desenvolvimento de Planos Formativos dirigidos ao Sector AgroindustrialPublication . Gaspar, Pedro DinisO projecto “AgriTraining–Formação aplicada para o sector agroindustrial"- COMPETE - SIAC - AAC nº 03/SIAC/2009 - Projecto nº 8310, destina-se a criar condições para melhorar as competências técnicas e de gestão dos profissionais do sector agroindustrial, com uma intervenção traçada que teve por base diversos objectivos estratégicos. A actividade 7 do referido projecto visava: Preparar e fundamentar planos de formação para posterior submissão de candidaturas ao Programa Operacional Potencial Humano (POPH); Nestas condições, o presente relatório faz a apresentação dos planos de formação que se consideram adequados para responder às necessidades identificadas.
- Algorithm for path recognition in-between tree rows for agricultural wheeled-mobile robotsPublication . Ramos, Anderson Rocha; Gaspar, Pedro DinisMachine vision has been widely used in recent years in agriculture, as a tool to promote the automation of processes and increase the levels of productivity. The aim of this work is the development of a path recognition algorithm based on image processing to guide a terrestrial robot in-between tree rows. The proposed algorithm was developed using the software MATLAB, and it uses several image processing operations, such as threshold detection, morphological erosion, histogram equalization and the Hough transform, to find edge lines along tree rows on an image and to create a path to be followed by a mobile robot. To develop the algorithm, a set of images of different types of orchards was used, which made possible the construction of a method capable of identifying paths between trees of different heights and aspects. The algorithm was evaluated using several images with different characteristics of quality and the results showed that the proposed method can successfully detect a path in different types of environments.