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- O poder encantatório das crianças performersPublication . Fradique, Teresa
- Seismic design of RC frames retrofitted with concentric steel bracesPublication . Sousa, Romain; Castro, J. MiguelThe implementation in Europe of a new seismic design code (Eurocode 8) will impose strict performance requirements to building structures. This will result in a significant number of existing reinforced concrete structures showing inadequate seismic resistance and hence requiring intervention. One of the available retrofitting techniques consists of inserting steel braces in the original RC structure. In spite of the advantages of using this retrofitting approach, the adoption of this technique is still limited due to the lack of seismic design rules. The interaction between the steel braces and the RC members turns the design in an intricate task. The main goal of the research presented in this paper was to develop a simple yet reliable design procedure that can promote the retrofitting of reinforced concrete frames with steel braces. The proposed method is based on displacements and accounts for the interaction of the steel elements on the deformation capacity of the RC members. To this end, nonlinear static and time-history analysis of reinforced concrete structures strengthened with concentric steel braces have been performed with the objective of deriving a number of key parameters (displacement profiles, yield drifts and target displacements) which are essential for the application of the new design procedure. The paper closes with an application of the proposed method to a RC structure with inadequate seismic resistance. The performance assessment of the retrofitted structure, carried out with nonlinear static analysis, confirms the validity of the design procedure and demonstrates the merits of adopting displacement-based seismic design approaches.
- Radio Frequency Numerical Simulation Techniques Based on Multirate Runge‐Kutta SchemesPublication . Oliveira, Jorge F.; Pedro, José C.; Oluwole D. MakindeElectronic circuit simulation, especially for radio frequency (RF) and microwave telecommunications, is being challenged by increasingly complex applications presenting signals of very different nature and evolving on widely separated time scales. In this paper, we will briefly review some recently developed ways to address these challenges, by describing some advanced numerical simulation techniques based on multirate Runge‐Kutta schemes, which operate in the one‐dimensional time and also within multidimensional frameworks.
- On the optimal shape of hip implantsPublication . Ruben, Rui; Fernandes, Paulo R.; Folgado, JoãoThe success of a total hip arthroplasty is strongly related to the initial stability of the femoral component and to the stress shielding effect. In fact, for cementless stems, initial stability is essential to promote bone ingrowth into the stem coating. An inefficient primary stability is also a cause of thigh pain. In addition, the bone adaptation after the surgery can lead to an excessive bone loss and, consequently, can compromise the success of the implant. These factors depend on prosthesis design, namely on material, interface conditions and shape. Although, surgeons use stems with very different geometries, new computational tools using structural optimization methods have been used to achieve a better design in order to improve initial stability and therefore, the implant durability. In this work, a multi-criteria shape optimization process is developed to study the relationship between implants performance and geometry. The multi-criteria objective function takes into account the initial stability of the femoral stem and the effect of stress shielding on bone adaptation after the surgery. Then, the optimized stems are tested using a concurrent model for bone remodeling and osseointegration to evaluate long-term performance. Additionally, the sensitivity to misalignments is analyzed, since femoral stems are often placed in varus or valgus position. Results show that the different criteria are contradictory resulting in different characteristics for the hip stem. However, the multi-criteria formulation leads to compromise solutions, with a combination of the geometric characteristics obtained for each criterion separately.
- Compressive strength of micropile-to-grout connectionsPublication . Veludo, J.; Júlio, E.N.B.S.; Dias-da-Costa, D.Strengthening foundations with micropiles is progressively being used, due to the major advantages that this technique presents. Nevertheless, the influence of some relevant parameters in the overall behavior of the retrofitted foundations has not yet been studied. Generally, micropiles are installed in holes drilled through the existing RC footing, which are then filled with grout. The efficiency of the load transfer mechanism depends on the bond strength of both the micropile-grout and the concrete-grout interfaces. This paper describes an experimental study performed to specifically study the influence of the following parameters on the bond strength between micropile-grout interface: hole diameter; embedment length of the micropile; and level of confinement of the grout mass. Thirty micropile-grout specimens were submitted to monotonic push-off tests, until failure. Bond strength was found to increase with a decrease of the hole diameter and with an increase of the confinement level. © 2011 Elsevier Ltd. All rights reserved.
- Empresa familiar y bolsa: análisis de rentabilidad y estrategias de inversiónPublication . Marcelo, José Luis Miralles; Quirós, María del Mar Miralles; Lisboa, InêsEl objetivo de este estudio consiste en analizar las diferencias en rentabilidad entre las empresas familiares y no familiares cotizadas en la bolsa española durante el periodo 1999-2008. El estudio se completa con un análisis comparado de la exposición frente al riesgo de estos dos tipos de empresa, los benefi cios obtenidos de una estrategia de inversión de coste cero basada en estar largo en empresas familiares y corto en empresas no familiares, así como la infl uencia en los resultados de los efectos fundador y tamaño. Los principales resultados obtenidos contradicen la evidencia empírica previa y señalan la posibilidad de obtener benefi cios extraordinarios invirtiendo en empresas familiares de reducido tamaño así como la mayor exposición frente al riesgo de las empresas directamente gestionadas por su fundador. Estos resultados son especialmente relevantes para los inversores tanto individuales como institucionales, para los académicos, así como para los dirigentes de este tipo de empresas.
- PLAYER – a European Project and a Game to Foster Entrepreneurship Education for Young PeoplePublication . Fonseca, Benjamim; Morgado, Leonel; Paredes, Hugo; Martins, Paulo; Gonçalves, Ramiro; Neves, Pedro; Nunes, Ricardo Rodrigues; Lima, Jorge; Varajão, João; Pereira, Angela; Sanders, Robert; Barracho, Vera; Lapajne, Urban; Rus, Matej; Rahe, Martin; Mostert, Andre; Klein, Thorsten; Bojovic, Viktorija; Bošnjak, Saša; Bošnjak, Zita; Carvalho, João; Duarte, Isabel; Casaramona, Andreana; Soraci, AlbertoEntrepreneurship is widely recognized as one of the basic skills to be acquired through a life-long learning. The European Union, under the guidance of the Oslo Agenda, promotes several initiatives to develop entrepreneurship culture in Europe. Education can make a significant contribution to entrepreneurship, encouraging the development of ntrepreneurial attitudes and skills in young people. Serious Games are presently recognised as having an important role and potential in education and social networks emerged in the last years as the platform preferred by many, especially young people, to socialize, play games and even learn. This paper presents the PLAYER project, in which a game was developed and implemented as a Facebook application, to enable learning entrepreneurial skills progressively, by guiding users to develop a business idea in the form of a business plan.
- La insolvencia de los consumidores en el derecho positivo español y portugués: retrato de una reforma inacabadaPublication . Conceição, Ana Filipa; Frade, Catarina Ferreira; Ávila de la Torre, Alfredo
- Carica papaya latex: A low‐cost biocatalyst for human milk fat substitutes productionPublication . Tecelão, Carla; Rivera, Ivanna; Sandoval, Georgina; Ferreira‐Dias, SuzanaAbstractThis work aims at evaluating the potential of Carica papaya lipase (CPL) self‐immobilized in papaya latex as a biocatalyst for the synthesis of human milk fat substitutes (HMFS), to be used as a low‐cost alternative to commercial lipases. Two different CPL preparations, one extracted from the papaya fruit (CPL I) and the other from petiole leaves (CPL II) of papaya tree, were tested as catalysts for the acidolysis between tripalmitin and (i) oleic acid or (ii) omega‐3 PUFA, batchwise, at 60°C, in solvent‐free media. After 24 h, molar incorporation was higher for oleic acid (22.1 mol%) when CPL I was used. This biocatalyst was selected for further studies. RSM was used to model reaction conditions: medium formulation (molar ratio oleic acid/tripalmitin, MR, 1.2:1–6.8:1) and temperature (58–72°C). Acyl migration decreased with MR increase. In batch operational stability assays at 60°C, using MR of 2:1 and 6:1, the highest stability was observed for a MR of 2:1.Practical applications: The use of this biocatalyst is a feasible way to valorize papaya agro‐residues which represent an important environmental problem in the producing countries. The obtained results were rather promising since, with this almost zero‐cost biocatalyst, it was possible to produce a high added‐value product (HMFS). Under optimized conditions, the obtained results were comparable with those obtained with expensive immobilized commercial lipases.
- Effect of process parameters on the morphological and mechanical properties of 3D Bioextruded poly(ε‐caprolactone) scaffoldsPublication . Domingos, M.; Chiellini, F.; Gloria, A.; Ambrosio, L.; Bártolo, P.; Chiellini, E.Purpose – This paper aims to report a detailed study regarding the influence of process parameters on the morphological/mechanical properties of poly(1-caprolactone) (PCL) scaffolds manufactured by using a novel extrusion-based system that is called BioExtruder. Design/methodology/approach – In this study the authors focused investigations on four parameters, namely the liquefier temperature (LT), screw rotation velocity (SRV), deposition velocity (DV) and slice thickness (ST). Scaffolds were fabricated by employing three different values of each parameter. Through a series of trials, scaffolds were manufactured varying iteratively one parameter while maintaining constant the other ones. The morphology of the structures was investigated using a scanning electron microscope (SEM), whilst the mechanical performance was assessed though compression tests. Findings – Experimental results highlight a direct influence of the process parameters on the PCL scaffolds properties. In particular, DV and SRV have the highest influence in terms of road width (RW) and consequently on the porosity and mechanical behaviour of the structures. Research limitations/implications – The effect of process and design parameters on the biological response of scaffolds is currently under investigation. Originality/value – The output of this work provides a major insight into the effect of process parameters on the morphological/mechanical properties of PCL scaffolds. Moreover, the potential and feasibility of this novel extrusion-based system open a new opportunity to study how structural features may influence the characteristics and performances of the scaffolds, enabling the development of integrated biomechanical models that can be used in CAD systems to manufacture customized structures for tissue regeneration.