Export 9208 results:
Sort by: Author Title Type [ Year  (Desc)]
2018
Bashir, {Safia Babikir}, {Hasan A. } Zidan, and Stanimir Valtchev. "An Improved Voltage Ripple Control Algorithm for Modular Multilevel Converter Based Variable Speed Drive." Proceedings - 2018 IEEE 18th International Conference on Power Electronics and Motion Control, PEMC 2018. United States: Institute of Electrical and Electronics Engineers Inc., 2018. 968-973. Abstract

Modular Multilevel Converter (MMC) is one of the most promising topologies for high power-medium voltage application. However, the use of MMC in variable speed drive applications is still limited. This is due to the fact that the fluctuation of the submodules capacitor voltage is large at low speed constant torque operation. This paper proposes an improved balancing approach based on Space Vector Pulse Width Modulation (SVPWM). The proposed method uses only one SVPWM, which not only simplifies the calculation but also reduces the submodules capacitor fluctuation and the circulating current in the MMC, thereby allowing the operation of MMC-based variable speed drive over the entire operating speed range and improve the converter efficiency. The closed loop operation of the MMC-based variable speed drive is verified through extensive simulations.

Mudrov, Mikhail, Anatoliy Ziuzev, Konstantin Nesterov, and Stanimir Valtchev. "Electric Drives Power-Hardware-in-the-Loop System Structures." 2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe. United States: Institute of Electrical and Electronics Engineers Inc., 2018. Abstract

Power-Hardware-in-the-Loop (PHiL) system for electric drives application based on power converter with Field Programmable Gate Array (FPGA)-based control system is discussed. PHiL structures are under discussion as well. During the PHiL mathematical model analysis instantaneous current repeating quality is increased. Variable frequency drive (VFD) was selected for testing.

Rebelo, H. B., A. Gregório, P. A. R. Rosa, D. Lecompte, and C. Cismaşiu. "Experimental characterization of 3D-printed PLA under uniaxial high strain-rate loading." AuxDefense 2018 – 1st World Conference on Advanced Materials for Defense. Lisbon 2018. auxdefense_extabstract_v2.pdf
Yang, Yongming, Manuel A. G. Silva, Hugo Biscaia, and Carlos Chastre. "CFRP-to-steel bonded joints subjected to cyclic loading: An experimental study." Composites Part B: Engineering. 146 (2018): 28-41. AbstractWebsite

Pseudo-cyclic and cyclic loading were applied to CFRP-to-steel bonded joints built with two different CFRP laminates. In this paper, the strength capacity and bond-slip curves are presented and compared. The modes of failure are also described and associated with the types of material used, and the observed performances are correlated. The analysis of the results showed a threshold value for loading and amplitude level, below which the cyclic loading caused no detectable damage. For cycles above that limit, the region of the joints around the loaded end presented degradation reflected on the bond-slip stiffness and on the increase of residual deformation. It was found that the normalized dissipated energies either obtained from the bond-slip relationship or from the load-slip response had the same trend. The experimental data allowed also to establish a relationship between the damage developed within the interface and the normalized slip. A preliminary estimate of fatigue limit based on those data is suggested.

Baikova, {E. N. }, L. Romba, R. Melicio, and {S. S. } Valtchev. "Simulation and experiment on electric field emissions generated by wireless energy transfer." Technological Innovation for Resilient Systems - 9th IFIP WG 5.5/SOCOLNET Advanced Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2018, Proceedings. Eds. {L. M. } Camarinha-Matos, {K. O. } Adu-Kankam, and M. Julashokri. IFIP Advances in Information and Communication Technology. Springer New York LLC, 2018. 243-251. Abstract

This paper presents a wireless energy transfer (WET) system operating at the frequency of tens of kHz. It treats the modeling and simulation of WET prototype and its comparison with experimental measuring results. The wireless energy transfer system model was created to simulate the electric field between the emitting and the receiving coils, applying the finite element method. The results from the simulation are compared to the measured values of the electric field emission from the wireless energy transfer equipment. In the recent years the interest in the WET technology, especially for the electric vehicles (EV) batteries charging, is rapidly growing. The WET systems pollute the environment by electromagnetic emissions. Due to the expanding use of this technology in industrial and consumer electronics products, the problems associated with the electromagnetic compatibility (EMC), and the adverse impact on the human health becomes highly important.

Romba, L., {E. N. } Baikova, C. Borges, R. Melicio, and {S. S. } Valtchev. "Wireless battery charger for EV with circular or planar coils: comparison." Technological Innovation for Resilient Systems - 9th IFIP WG 5.5/SOCOLNET Advanced Doctoral Conference on Computing, Electrical and Industrial Systems, DoCEIS 2018, Proceedings. Eds. {L. M. } Camarinha-Matos, {K. O. } Adu-Kankam, and M. Julashokri. IFIP Advances in Information and Communication Technology. Springer New York LLC, 2018. 214-223. Abstract

This paper presents the experimental results obtained in the wireless energy transfer (WET) system prototype based on coils: circular or planar. With these experimental results we can choose the tuning settings to improve the efficiency of power transmission of the WET systems. In WET for electric vehicle batteries charging, the coil shape and the range between the coils are the most important issues of those systems.

Marzola, M., O. Mateus, and(eds) M. Moreno-Azanza Abstract book of the XVI Annual Meeting of the European Association of Vertebrate Palaeontology. XVI Annual Meeting of the European Association of Vertebrate Palaeontologists. Caparica: Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, 2018.eavp_2018_abstract_book.pdf
Bedon, Chiara, Michel Arrigoni, Filipe Santos, and Lucia Figuli Advancements in Design and Analysis of Protective Structures. Hindawi, 2018.
Costa, F., and O. Mateus Alcovasaurus longispinus as a dacentrurine stegosaur (Dinosauria) and contributions to the diagnosis of Dacentrurinae. XVI Annual Meeting of the European Association of Vertebrate Palaeontologists, .Abstract Book. Abstract book of the XVI Annual Meeting of the European Association of Vertebrate Palaeontologists, Caparica, Portugal June 26th-July 1st, 2018., 2018. Abstractcosta__mateus_2018_eavp_abstract.pdf

n/a

Pilco, H., Sanchez-Gordon, S., Calle-Jimenez, T., Rybarczyk, Y., Jadán, J., Villarreal, S., Esparza, D., Acosta-Vargas, P., Guevara, C., Nunes, and I. "Analysis and improvement of the usability of a tele-rehabilitation platform for hip surgery patients." 9th International Conference on Applied Human Factors and Ergonomics. Orlando, USA 2018.
Calle-Jimenez, T., Sanchez-Gordon, S., Rybarczyk, Y., Jadán, J., Villarreal, S., Esparza, D., Acosta-Vargas, P., Guevara, C., and Nunes I. "Analysis and improvement of the Web accessibility of a tele-rehabilitation platform for hip arthroplasty patients." 9th International Conference on Applied Human Factors and Ergonomics. Orlando, USA 2018.
Figueiredo, E., J. Fonte, A. Lima, JP Veiga, R. J. C. Silva, and J. Mirão. "Ancient tin production: Slags from the Iron Age Carvalhelhos hillfort (NW Iberian Peninsula)." Journal of Archaeological Science. 93 (2018): 1-16.
Petrova, K. T., M. T. Barros, R. C. Calhelha, M. Sokovic, and I. C. F. R. Ferreira. "Antimicrobial and cytotoxic activities of short carbon chain unsaturated sucrose esters." Med. Chem. Res. 27.3 (2018): 980-988. DOI: 10.1007/s00044-017-2121-5.
Mar, Adriana, Fernando Monteiro, Pedro Pereira, and João Martins. "An Application to Improve Smart Heritage City Experience." Advances in Digital Cultural Heritage. Eds. Marinos Ioannides, João Martins, Roko Żarnić, and Veranika Lim. Cham: Springer International Publishing, 2018. 89-103. Abstract

Nowadays technologies relate to so many aspects in our daily life that makes society eager for more and more ways of using it. To keep up with this new technological world, all economic sectors, from industry to services, are trying to adapt their products into this new reality. Presently, cultural heritage is already a field where the application of technology allows a static site to be converted into an intelligent environment, with detailed information about a specific monument or historical place, becoming more interesting, not only for local habitants, but also for tourists. This paper describes an application that allows tourists, managers and historical sites' habitants to experience a completely new way of discovering those places, offering a visit with detailed real-time information taking into account their personal interests. Tourists will have at their disposal a full set of optimized routes, combining their interests with their visiting time.

Gouveia, Nuno D., Duarte M. V. Faria, and António Pinho Ramos. "Assessment of SFRC flat slab punching behaviour – Part I: monotonic vertical loading." Magazine of Concrete Research (2018): 1-46. AbstractWebsite

This paper presents a study of the behaviour and load capacity of Steel Fibre Reinforced Concrete (SFRC) flat slabs under monotonically increased concentrated vertical loads. The SFRC was used only in the local region of the slab-column connection, as the rest of the slab was cast using normal concrete (NC) without fibres. The six experimental test specimens had a thickness of 150 mm with different longitudinal reinforcement ratios, using a non-uniform distribution over the slab width. The concretes used were made with different Dramix® 4D 65/60 BG steel fibre contents (0%, 0.5 %, 0.75% and 1.0% volume content). The slab tests were complemented by flexural tests on notched-beams. This made it possible to determine the tension behaviour of the different concretes used, through a linear post-cracking behavior and inverse analysis. The inverse analysis made it possible to define the stress-crack opening relationship that characterize the tension behaviour of SFRC and to relate it to the observed behaviour and load capacity of the tested slabs. The tests results show that the tensile behaviour of the SFRC plays an important role in the behavioural and load capacity of the slabs and that it can be considered relevant to physically based models.

Gouveia, Nuno D., Duarte M. V. Faria, and António Pinho Ramos. "Assessment of SFRC flat slab punching behaviour – part II: reversed horizontal cyclic loading." Magazine of Concrete Research (2018): 1-17. AbstractWebsite

This paper presents an experimental study of four flat slab specimens subjected to combined vertical and horizontal cyclic loading. Steel fibre-reinforced concrete (SFRC) was used only in the local region of the slab–column connection, while the rest of the slabs were cast using normal concrete. The specimens measured 4·15 m × 1·85 m × 0·15 m and were connected to two steel half columns by 0·25 m × 0·25 m rigid steel plates, prestressed against the slab using steel bolts, to ensure monolithic behaviour. The specimens were tested using an innovative test setup system that accounted for important factors, such as the ability of bending moment redistribution, line of inflection mobility and assured equal vertical displacements at the opposite slab borders, and symmetrical shear forces. Results show that the presence of SFRC in the slab–column connection region is effective in increasing the deformation capacity of slab–column connections, allowing the increase of horizontal drift ratios.

Roque, C., and H. Rocha Avaliação formativa com recurso à tecnologia [Formative assessment using technology]. SIEM. Almada, Portugal: APM, 2018. Abstract

The present study aims to understand the potentialities and implications,
to the teacher and her practice, of the use of formative assessment with the support
of educational technology.
Regarding the research methodology, this study is part of the research on own
practice. The participants were the teacher, who was simultaneously a researcher,
and the students of a 9th grade class.
In the course of this experience it was found that the use of formative assessment
allows, on the one hand, the student to realize what he manages to understand, and
what he has to do to overcome what are less consolidated parts of the content in
study; and, on the other, the teacher to detect in a timely manner the difficulties of
the student and to change strategies to allow the student to overcome his difficulties.
The lack of time, the difficulties in managing the curriculum and the existence of
national exams are three of the main obstacles mentioned by the teachers for the
non-realization of formative assessment. In this experience it was found that the use
of new technologies turns possible to overcome these limitations.
This type of assessment had a very positive impact on teacher’s practice and in the
learning of the students.
Keywords: assessment; formative assessment; new technologies.

Luísa, Ana. "baba." Indcro. 77 (2018): 23-25.
Almeida, Bernardo F., Isabel Correia, and Francisco Saldanha-da-Gama. "A biased random-key genetic algorithm for the project scheduling problem with flexible resources." TOP. 26 (2018): 283-308.
Eliseu, Manuel, Maria Isabel Gomes, and Angel A. Juan. "A Biased-Randomized Heuristic for the Home Healthcare Routing Problem." IO 2017, in ”, Springer Proceedings in Mathematics and Statistics series. Valença, Portugal 2018.
G, Gomes, Lúcio V, Cismasiu C, and Rebelo H. B. "Blast Assessment - uma metodologia de avaliação." Construção Magazine.86 (2018): 18-23.
Carvalho, F., A. Lopes, A. T. Curulli, TP Silva, M. M. A. Lima, G. Montesperelli, S. Ronca, G. Padeletti, and JP Veiga. "The Case Study of the Medieval Town Walls of Gubbio in Italy: First Results on the Characterization of Mortars and Binders." Heritage. 1.2 (2018): 468-478.
Moniz, António B. "Cenários sobre o futuro do trabalho: avaliação das implicações tecnológicas [Scenarios on the Future of Work: Assessment of technological implications]." Prospetiva Estratégica – Teoria, Métodos e Casos Reais [Strategic Foresight – Theory, Methods and Real cases]. Eds. José Saragoça, Carlos A. Silva, and Joaquim Fialho. Lisboa: Ed. Silabo, 2018. 173-197.
Raposo, P., J. Martins, J. Correia, Maria E. Salavessa, Cristina Reis, José Xavier, and Abilio M. P. de Jesus. "Characterization of the mechanical behaviour of wooden construction materials from quinta lobeira de cima." International Journal of Structural Integrity. 9 (2018): 396-410. AbstractWebsite

Purpose The antique structures are part of the inheritance that our elders left, being important to preserve their memories. It is important to preserve, rehabilitate and restore the historic buildings protecting the cultural patrimony, attending to the actual comfort and habitability requirements. It is necessary to study the behaviour of the various elements that compose antique structures (masonry and wood) in order to develop assessment measures according to the characteristics of the original materials. The paper aims to discuss these issues. Design/methodology/approach An experimental campaign to characterize the mechanical behaviour of the wood of the roof of the �sequeiro� of �Quinta Lobeira de Cima�, a building from the twentieth century located in Minho, was carried out. The tested wood specimens are from two different species: chestnut and oak. Compression, tension and static flexion tests according to parallel to the grain direction were performed. Other parameters, such as density, moisture content and longitudinal modulus of elasticity in compression and in tension, were also obtained. The measurement of displacements was made with Digital Image Correlation (DIC). Findings The results of this study show the similarity between experimental and empirical values for the studied woods species. Originality/value This original study aimed at characterizing the mechanical properties using DIC of wood of the roof of the �sequeiro� of �Quinta Lobeira de Cima�, a building from the twentieth century located in Minho (Portugal). This study is part of master thesis of Jo�o Martins, an original research work.