Export 9208 results:
Sort by: Author Title Type [ Year  (Desc)]
2020
Fernandes, Cláudio A., and Alexei Yu. Karlovich. "Semi-almost periodic Fourier multipliers on rearrangement-invariant spaces with suitable Muckenhoupt weights." Boletín de la Sociedad Matemática Mexicana. 26.3 (2020): 1135-1162.Website
Torabian, Ala, Brisid Isufi, Davood Mostofinejad, and António Pinho Ramos. "Shear and flexural strengthening of deficient flat slabs with post-installed bolts and CFRP composites bonded through EBR and EBROG." Structural Concrete. n/a (2020). AbstractWebsite

Abstract Fiber reinforced polymer (FRP) composites can be efficient for flexural strengthening of flat slabs if debonding of the FRP is postponed. However, with the increase of the flexural capacity, the flat slab becomes more susceptible to punching shear failure. In this context, four flexural or simultaneous flexural and punching shear retrofitting systems are investigated in this study to strengthen a flexure-deficient flat slab. Externally Bonded Reinforcement on Grooves (EBROG) and externally bonded reinforcement (EBR) methods are used for flexural strengthening in two cases: slabs without punching shear reinforcement and with post-installed shear bolts as shear reinforcement. According to the results, flexural strengthening of the slab using the EBR and EBROG techniques increased its load capacity by 12% and 21%, respectively. Simultaneous flexural and shear strengthening of the slab using the EBROG technique was the most effective, leading to a 57% enhancement of the load capacity. For specimens whose failure was governed by punching, comparing the results with code predictions showed that Eurocode and ACI (and the respective guide documents fib bulletin 90 and ACI 440.2R) overestimated the capacity of these specimens. In cases where failure was governed by flexure, a simple application of the yield line theory predicted reasonably well the load capacity of the specimens.

Torres, D., C. Pimentel, and S. Duarte. "Shop floor management system in the context of smart manufacturing: a case study." International Journal of Lean Six Sigma,. 11.5 (2020): 837-862.
Coronelli, Dario, Aurelio Muttoni, Ion R. Pascu, Antonio P. Ramos, and Teresa Netti. "A state of the art of flat-slab frame tests for gravity and lateral loading." Structural Concrete. n/a (2020). AbstractWebsite

Abstract This paper presents a critical review of the state of the art of experimental research concerning the seismic response of reinforced concrete flat slab frames. After a summary of tests on connections, the paper examines tests carried out on frames with gravity and cyclic lateral loading, and shake table tests; scaled specimens and one real scale study are included. A discussion of the results reached so far is provided focusing on the global response, the different load types and effects; the ultimate rotations at failure in relation to the gravity shear and a classification of different failure modes for different types of connections. Based on this analysis, the research needs are highlighted. An experimental program launched to address these open questions is described. Further open topics are highlighted.

Marques, Sofia Santos; Artur Silva; Manuel A. M. S. M. B. "Sustainable Amidation Reactions – Recent Advances." Eur J. Org. Chem. (2020). Abstract

Herein, we present a selection of sustainable amidation processes, that have contributed to solving the problems associated with traditional methods. Novel reagents and methods are described, including boron‐based reagents, the use of metallic and organometallic catalysts as well as metal‐free methods using milder and versatile oxidants.

Rocha, H., E. Faggiano, and F. Mennuni. "Teachers as task designers in the digital age: Teaching using technology." Proceedings of the 10th ERME Topic Conference - MEDA 2020. Linz (Austria): ERME, 2020. Abstract2020_meda_rocha_faggiano_mennuni.pdf

The aim of the paper is to present and analyse the case of one teacher attempting to introduce his students to fractals using digital technology. His task design process has been made explicit through the writing of a storyboard. It has been analysed in order to focus on the stages of the process, identifying prominent elements in it by using the knowledge quartet framework. Results can be useful to inform teacher educators about his needs with respect to the development of his ability in task design. The importance of this aspect, particularly worth of note in the digital age in which teachers have many opportunities to access teaching resources online, has been amplified by the constraints to which educational systems have been subjected during the Covid-19 pandemic emergency.

Clemmensen, L. B., D. V. Kent, M. Mau, O. Mateus, and J. Milàn. "Triassic lithostratigraphy of the Jameson Land basin (central East Greenland), with emphasis on the new Fleming Fjord Group." Bulletin of the Geological Society of Denmark. 68 (2020): 95-132. Abstractclemmensen_et_al_2020_triassic_lithostratigraphy_of_the_jameson_land_basin.pdfWebsite

The lithostratigraphy of the Triassic deposits of the Jameson Land Basin in central East Greenland is revised. The new Scoresby Land Supergroup is now composed of the Wordie Creek, Pingo Dal, Gipsdalen and Fleming Fjord Groups. This paper only deals with the lithostratigraphy of the late Early-Late Triassic continental deposits of the latter three groups with emphasis on the vertebratebearing Fleming Fjord Group. The new Pingo Dal Group consists of three new formations, the Rødstaken, Paradigmabjerg and Klitdal Formations (all elevated from members), the new Gipsdalen Group consists of three new formations, the Kolledalen, Solfaldsdal (with the new Gråklint Member) and Kap Seaforth Formations (all elevated from members), and the new Fleming Fjord Group is subdivided into three new formations, the Edderfugledal, Malmros Klint and Ørsted Dal Formations (all elevated from members). The Edderfugledal Formation contains two cyclic bedded, lacustrine members, a lowermost Sporfjeld Member (elevated from beds), and an uppermost Pingel Dal Member (elevated from beds). The lacustrine red beds of the Malmros Klint Formation are not subdivided. The lacustrine and fluvial Ørsted Dal Formation contains three new members. In the eastern and central part of the basin, the formation is initiated by cyclic bedded, red lacustrine mudstones of the Carlsberg Fjord Member (elevated from beds), while in the northwestern part of the basin the lowermost part of the formation is composed of grey fluvial conglomerates and sandstones with subordinate red mudstones of the Bjergkronerne Member (elevated from beds). The uppermost part of the formations in most of the basin is composed of cyclic bedded, variegated lacustrine mudstones and grey to yellowish marlstones of the Tait Bjerg Member (elevated from beds). The sediments in the Fleming Fjord Group contain remains of a rich and diverse vertebrate fauna including dinosaurs, amphibians, turtles, aeotosaurs, pterosaurs, phytosaurs and mammaliaforms. Most vertebrate bones have been found in uppermost Malmros Klint Formation, and in the Carlsberg Fjord and Tait Bjerg Members. The Norian–early Rhaetian, lacustrine Fleming Fjord Group was deposited at about 41° N on the northern part of the supercontinent Pangaea. Lacustrine sedimentation was controlled by seasonal as well as longer-term (orbital) variation in precipitation. Precipitation was probably brought to the basin by southwesterly winds. The lacustrine sediments of the uppermost Fleming Fjord Group show deposition during increasingly humid conditions changing the lake environment from an ephemeral lake-steppe area to a perennial lake. This evolution of lake environment suggests a change from a winter-wet temperate climate to one with precipitation throughout the year.

Rocha, H. "Using tasks to develop pre-service teachers’ knowledge for teaching mathematics with digital technology." ZDM Mathematics Education. 52.7 (2020): 1381-1396. AbstractWebsite

Teacher education is central to the development of the professional knowledge of pre-service teachers. The main goal of this paper is to refect on the development that the analysis (done by a group of pre-service secondary teachers) of a set of tasks, based on elements related to domains of KTMT—Knowledge for Teaching Mathematics with Technology—can bring to the knowledge of pre-service teachers of mathematics. Specifcally, the goal was to investigate the following questions: (1) What are the factors that guide the pre-service teachers’ task discussion? (2) Which KTMT domains are emphasized by pre-service teachers during task discussion? The elements taken into account are the characteristics of the tasks (focus on cognitive level, structuring level and technology role), the use of representations (focus on balance and articulation of representations), and the equilibrium between experimentation (focus on digital technology afordances) and justifcation (focus on argumentation and proof). The methodology of this case study involves a qualitative approach. The main conclusions suggest that infuences in the pre-service teachers’ discussion of tasks fell into the following categories: the potentialities of technology, the type of tasks, and the prospective teachers’ experience with a set of tasks, and analysis of some real students’ reports. With regard to KTMT, although it was possible to identify some global development, Teaching and Learning and Technology Knowledge was the domain in which stronger development took place.

Esgalhado, Filipa, Arnaldo Batista, Helena Mouriño, Sara Russo, Catarina Palma dos Reis, Fátima Serrano, Valentina Vassilenko, and Manuel Ortigueira. "Uterine contractions clustering based on electrohysterography." Computers in Biology and Medicine. 123.June (2020).
Boavida, Nuno, and António Brandão Moniz. "Virtual work in Portugal: a literature review." International Journal on Working Conditions.19 (2020): 1-15.Website
Jackson, Yasmin Jamalia, Rita C. Economos, Louis L. Jacobs, Octávio Mateus, and António Olímpio Gonçalves When dinosaurs walked through diamonds: constraining the age of Early Cretaceous footprints in volcanic crater sediments. 54th Annual GSA South-Central Section Meeting 2020. Fort Worth: Geological Society of America Abstracts with Programs. Vol. 52, No. 1, 2020.jackson_et_al_2020_abstract__when_dinosaurs_walked_through_diamonds__gsa.pdf
Laronha, H., I. Carpinteiro, J. Portugal, A. Azul, M. Polido, K. T. Petrova, M. Salema-Oom, and J. CALDEIRA. "“Challenges in Matrix Metalloproteinases Inhibition." Biomolecules. 10 (2020): 717-778. DOI:10.3390/biom10050717.
Biscaia, H. C., and S. Soares. "Adherence prediction between ribbed steel rebars and concrete: A new perspective and comparison with codes." Structures. 25 (2020): 979-999. AbstractWebsite

The interfacial behaviour between ribbed steel rebars and concrete has been extensively studied because the contribution of the adherence between these two materials is of the utmost importance for the behaviour of Reinforced Concrete (RC) structures. The majority of the available studies on this topic indicate that the local adherence between these two materials can be defined through a bond-slip relationship, which is obtained with short embedded lengths. Although this seems to be widely accepted, some incoherencies, mainly regarding the local and the global detachment process in that “conventional theory”, are identified in the present work. To facilitate the understanding of the detachment process between a ribbed steel rebar and concrete, an analytical solution is developed. An experimental program with 33 pull-out tests covering three different ribbed steel rebars with different diameters and embedded lengths was carried out. Based on the experimental load–displacement at the pulled end responses, a new local bond-slip relationship with friction is proposed. In the end, the new bond-slip relationship, as well as other known relationships, is implemented into a Finite Element (FE) commercial code and the results are compared to the experimental data. Based on these preliminary results and up to the yielding point of the steel rebars, the new proposed local bond-slip model is the only one able to clearly distinguish and simulate either the local and the global performances of the tested specimens. © 2020 Institution of Structural Engineers

Almeida, André F. O., António P. Ramos, Válter Lúcio, and Rui Marreiros. "Behavior of RC flat slabs with shear bolts under reversed horizontal cyclic loading." Structural Concrete. 21 (2020): 501-516. AbstractWebsite

Abstract An experimental work on reinforced concrete flat slab specimens to test the efficiency of postinstalled bolts, as punching shear reinforcement in resisting vertical and cyclic horizontal loads, was conducted and is presented in this paper. The test protocol consisted in increasing horizontal drifts combined with constant vertical load until failure. Two different detailing solutions for the shear reinforcement were considered, one using a radial distribution around the column and another using a cross distribution, being the results compared with a previously tested reference specimen. The dimensions of the specimens were 4.25 x 1.85 x 0.15 m3. The test setup used for these tests was developed by the research team and simulates the boundary conditions with already recognized good results. Postinstalled steel bolts were proven to be an efficient solution for strengthening of existing structures, improving the structural behavior, and the punching resistance.

Almeida, André F. O., Bruno Alcobia, Miguel Ornelas, Rui Marreiros, and António Pinho Ramos. "Behaviour of reinforced-concrete flat slabs with stirrups under reversed horizontal cyclic loading." Magazine of Concrete Research. 72 (2020): 339-356. AbstractWebsite

This paper describes the experimental campaign to study the behaviour of reinforced-concrete flat slab structures with steel stirrups as punching shear reinforcement, under combined vertical and horizontal cyclic loading. The vertical load was first applied and kept constant during the test, while, regarding the cyclic horizontal loading, imposed cyclic drifts were increased until failure. Four slab specimens with shear reinforcement were tested and the results compared to a control slab specimen without shear reinforcement. The studied variables were different shear reinforcement ratios and the number of stirrup layers. The slabs were 4·15 × 1·85 m2 and 0·15 m thick, connected to two steel half-columns. The test setup used was developed by the research team and aimed to simulate the boundary conditions of a flat slab, representing the slab between middle spans in one direction and between zero bending moment points in the other direction. Results show that the use of steel stirrups as shear reinforcement is very effective, increasing shear, drift and energy dissipation capacities. The obtained results were also compared to the provisions given by European and American codes.

Biscaia, H. C. "Closed-form solutions for modellingthe response of adhesively bonded joints under thermal loading through exponential softening laws." Mechanics of Materials. 148 (2020). AbstractWebsite

The bonding technique has received extensive attention in the recent decades. Unlike the use of metallic screws, screws or rivets, some of the advantages of this bonding technique include the elimination of stress concentration, lighter weight and the extension of the life cycle of the adhesively bonded structures. The stiffness and strength of a material are increased after bonding with another reinforced material, but it can only be effective if the interface is able to transfer bond stresses. However, how the bond stress transfer is carried out when the joint, reinforcement and substrate are subjected to a thermal loading is not yet well understood. One way to facilitate and improve such knowledge is to develop analytical solutions that, despite their simplicity, allow parameters to be identified that may directly influence the bond between materials. Therefore, the present study aims to develop a series of closed-form solutions able to describe the debonding process of bonded joints with different characteristics using two different exponential softening laws. The results mainly describe the interfacial slips, bond stresses and strains in both materials during the temperature increase process. In total, 108 examples with different bonding conditions are studied and, at the same time, numerically modelled through the Finite Element Method (FEM). The numerical results were compared to the proposed closed-form solutions and a satisfactory agreement was obtained between the numerical and analytical results, validating the latter. When considered in the simulations, the glass transition temperature (Tg) of the adhesive greatly affected the bond stress transfer between materials and compromising the initial integrity of the adhesively bonded structure. © 2020

Torres, Marta, João Correia de Freitas, and Mônica Mesquita. "Coconstrução de um museu virtual. {Literacia}, sustentabilidade e emancipação na disseminação do património cultural das comunidades de pescadores.". Lisboa 2020. Abstract

No contexto do Observatório de Literacia Oceânica, o estudo da coconstrução de um museu virtual online investiga a aprendizagem dos alunos pertencentes às comunidades piscatórias, contribuindo para a literacia histórica. O envolvimento em tarefas concretas associadas à aprendizagem é considerado, consensualmente, um fator de motivação. No presente estudo trabalharam as artes da pesca artesanal, enquadradas por conteú dos da disciplina de História. Utilizando ambientes tecnologicamente enriquecidos, pretende-se compreender as interações entre o conhecimento formal e informal destes alunos, desenvolvendo-se o estudo de forma a que os conhecimentos sejam signi{\textbackslash}icativos e usáveis, promovendo a intervenção na sociedade, enquanto agentes de mudança. A metodologia assentou num estudo empı́rico qualitativo, com base na etnogra{\textbackslash}ia crı́tica, combinado com design-based research, para a construção do protótipo do museu virtual online. As estratégias de ação, técnicas de recolha e aná lise de dados desenvolveram-se num contexto de observação participativa, notas de campo e aplicação de vários instrumentos, bem como na coconstrução do protótipo por aproximações sucessivas estruturantes da plataforma digital selecionada. Constatou-se a ausência de interação entre os saberes formais e informais dos alunos, um desconhecimento da história das suas comunidades, mas também a valorização das histórias de famı́lia. Os alunos foram observadores crı́ticos das suas práticas reconhecendo, por exemplo, a desvalorização dos seus saberes informais e a sua falta de relação com os conteú dos da disciplina de História. Neste processo identi{\textbackslash}icou-se a necessidade de introduzir temáticas relacionadas com a Literacia Histórica, História das Comunidades Capariquenses e Sustentabilidade, considerando-o o meio privilegiado para a disseminação do seu património cultural.

Gomes, M. I., F. Caeiro, F. Figueiredo, L. Henriques-Rodrigues, and D. Pestana. "Corrected-Hill versus partially reduced-bias value-at-risk estimation." Communications in Statistics: Simulation and Computation. 49 (2020): 867-885. Abstract
n/a
Penalva, H., M. Ivette Gomes, F. Caeiro, and M. Manuela Neves. "A couple of non reduced bias generalized means in extreme value theory: An asymptotic comparison." Revstat Statistical Journal. 18 (2020): 281-298. Abstract
n/a