ESTG - Artigos em revistas internacionais
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- Innovative capabilities: Their drivers and effects on current and future performancePublication . Lisboa, Ana; Skarmeas, Dionysis; Lages, CarmenThis study investigates the role of a firm's orientation, both customer and competitor, in driving innovative capabilities and the impact of those capabilities on a firm's current and future performance. The study's contribution is threefold in that it (1) examines market-related exploitative and explorative capabilities in conjunction with product development exploitative and explorative capabilities in terms of their strategic drivers (firm orientation) and performance outcomes; (2) disentangles the effects of exploitative and explorative capabilities on current and future performance; and (3) examines the role of innovative capabilities within the particularly relevant, but understudied, context of exporting. The findings suggest that, although customer orientation relates to both exploitative and explorative capabilities, competitor orientation relates only to exploitative capabilities. Exploitative capabilities affect current performance, whereas explorative capabilities affect future performance. These findings are of crucial relevance to export managers in their quest to identify, extend, and create new market opportunities.
- Entrepreneurial orientation, exploitative and explorative capabilities, and performance outcomes in export markets: A resource-based approachPublication . Lisboa, Ana; Skarmeas, Dionysis; Lages, CarmenInnovation is critical to the growth and success of a firm. In an attempt to renew themselves and compete effectively in the global marketplace, firms must possess both technical and non-technical capabilities. Yet, the extant literature has mainly focused on technology and product development capabilities, disregarding other possible capability domains. This study investigates the role of market-related exploitative and explorative capabilities, together with product development ones, in the context of exporting. Drawing on the resource-based and organization learning theories, we examine the internal process through which entrepreneurial orientation influences performance in export markets and develop a model of entrepreneurial orientation–exploitative and explorative capabilities–advantage–performance relationships. The results indicate that entrepreneurial orientation is a precursor of exploitative and explorative product development and overseas market-related capabilities. The findings also suggest that product development explorative capabilities and overseas market-related exploitative capabilities have a positive effect on new product differentiation, which in turn enhances market effectiveness. Implications for scholars and practitioners are discussed along with suggestions for future research.
- Complexity control of high efficiency video encoders for power-constrained devicesPublication . Correa, Guilherme; Assunção, Pedro; Agostini, Luciano; Cruz, Luis da SilvaThe emerging High Efficiency Video Coding (HEVC) standard is expected to require much more processing power than its predecessors due to the higher algorithmic complexity of new coding tools and associated data structures. This paper proposes a novel complexity control method for the near future HEVC encoders running on power-constrained devices. The proposed method is based on a decision algorithm that dynamically adjusts the depth of the Coding Units (CU) defined by quad-tree structures. New evidence about the relationship between CU depth and coding complexity is used to selectively constrain the CU depth in order to not exceed a predefined complexity target. The experimental results show that the encoder computational complexity can be downscaled by up to 60% at the cost of negligible loss of rate-distortion (RD) performance. The proposed method finds application in the near future multimedia portable devices using HEVC codecs1.
- Digital forensic artifacts of the Your Phone application in Windows 10Publication . Domingues, Patrício; Frade, Miguel; Andrade, Luis Miguel; Silva, João VictorYour Phone is a Microsoft system that comprises two applications: a smartphone app for Android 7 + smartphones and a desktop application for Windows 10/18.03+. It allows users to access their most recent smartphone-stored photos/screenshots and send/receive short message service (SMS) and multimedia messaging service (MMS) within their Your Phone-linked Windows 10 personal computers. In this paper, we analyze the digital forensic artifacts created at Windows 10 personal computers whose users have the Your Phone system installed and activated. Our results show that besides the most recent 25 photos/screenshots and the content of the last 30-day of sent/received SMS/MMS, the contact database of the linked smartphone(s) is available in a accessible SQLite3 database kept at the Windows 10 system. This way, when the linked smartphone cannot be forensically analyzed, data gathered through the Your Phone artifacts may constitute a valuable digital forensic asset. Furthermore, to explore and export the main data of the Your Phone database as well as recoverable deleted data, a set of python scripts – Your Phone Analyzer (YPA) – is presented. YPA is available wrapped within an Autopsy module to assist digital practitioners to extract the main artifacts from the Your Phone system.
- Fatigue crack propagation along interfaces of selective laser melting steel hybrid partsPublication . Santos, Luis M.S.; Ferreira, José A.M.; Borrego, Luis P.; Costa, Jose D.; Capela, Carlos; Jesus, Joel deSelective laser melting (SLM) is an emerging additive manufacturing technology, capable of producing complex geometry components. The current work studied both the effect of substrate material and mean stress on the fatigue crack growth behaviour along interfaces of bi‐material specimens, substrate, and part by SLM. Fatigue tests were carried out in agreement with ASTM E647 standard, using 6‐mm‐thick compact specimens. The substrate steel has only a negligible effect both on the fatigue crack propagation rate and on the crack path. The failure occurs in the material additively manufactured by SLM, near the interface. The mean stress produced only a reduced influence on the fatigue crack propagation rate in the Paris regime. For larger values of ΔK, where Kmax approaches KIc, a significant influence of the mean stress was observed. In spite of nondetection of crack closure, the application of overloads promoted significant fatigue crack retardation, quite similar for both substrate materials, probably due to the crack bifurcation during the overload.
- Removing Barriers to Promote Social Computing among Senior PopulationPublication . Marcelino, Isabel; Laza, Rosalía; Fdez-Riverola, Florentino; Pereira, AntónioSmartphones and tablets proliferation enabled by accessible prices and also by the inclusion of sensing abilities promotes their use in several areas, such as healthcare. It opens new horizons in the field of continuous and noninvasive monitoring and support to population, namely, to seniors. Despite the great benefits that mobile sensing and social computing could provide to increase elderly’s quality of life, many studies have shown that elderlies deal with difficulty with Information and Communication Technology (ICT). In this paper we present a solution to overcome barriers between elderlies and their ICT usage in order to potentiate all the benefits provided from mobile sensing and social computing. A survey on guidelines, standards, and advice regarding usability and accessibility issues when developing solutions for elderly people was carried out. This survey was made having in mind that senior population have singular requirements due to age related changes and also frequently technological illiteracy. We have identified and applied the most important guidelines to our solution. A prototype was made using responsive design in order to be adaptable to any type of devices. Regarding evaluation, usability tests and semistructured interviews were conducted in real scenario.
- Does Printing Orientation Matter in PolyJet 3D Printed Teeth for Endodontics? A Micro-CT AnalysisPublication . Barbosa, Cláudia; Reis, Tiago; Reis, José B.; Franco, Margarida; Batista, Catarina; Ruben, Rui B.; Martín-Biedma, Benjamín; Martín-Cruces, JoseThis study aimed to identify the optimal printing orientation (X, Y, or Z axis) and positioning of a mandibular molar presenting an isthmus using PolyJet™ technology. The influence of these parameters on dimensional accuracy and on the behavior of 3D-printed teeth (3DPT) during endodontic preparation with ProTaper Gold® system was evaluated. Six groups (XA, XB, YA, YB, ZA, ZB; n = 10) were printed with different axis orientations and distinct isthmus positions relative to the build platform. All samples underwent micro-computed tomography scanning before and after endodontic preparation. Regarding preoperative analyses—canal volume, centroids, and total tooth volume and area—no significant differences were found between groups XA–YA or XB–YB (p > 0.05), supporting their comparability. In contrast, groups ZA and ZB differed significantly from all others (p < 0.05), failing to meet equivalence required for further comparison, and were therefore excluded. Postoperative evaluation—volume change, centroid displacement, transportation, and unprepared areas—revealed no significant differences between XA–YA and XB–YB. Within the limitations of this study, both printing orientation and position affected the accuracy and repeatability of 3DPT, with positioning exerting the greatest influence, while their behavior towards endodontic preparation remained consistent across orientations.
- Experimental characterization of the out-of-plane behaviour of masonry infill walls made of lightweight concrete blocksPublication . Agante, Marta; Furtado, André; Rodrigues, Hugo; Arêde, António; Fernandes, Paulo; Varum, HumbertoMasonry infill walls are widely spread over the reinforced concrete buildings due to different demands. The buildings' thermal energy efficiency is a top priority nowadays since many of the existing building stock comprises buildings with low energy performance. The buildings' external envelope is undergoing a transformation with the vertical hollow concrete blocks' appearance with high thermal and acoustic demands. However, recent evidence from a strong earthquake shows that the masonry infill walls are quite vulnerable to out-of-plane loadings and were responsible for many casualties, injuries and economic losses. Based on that, this work's main objective is to study the out-of-plane (OOP) behaviour of masonry infills made with vertical hollow concrete blocks. The experimental campaign comprises the OOP testing of three full-scale infill walls made up of these masonry units, one of them as-built without previous damage, one with previous damage due to an earlier in-plane test and the third one retrofitted. All the tests consisted of applying the loading–unloading-reloading history of imposed displacements in the OOP direction through a uniformly distributed load. The results will be presented in terms of OOP force–displacement responses, damage evolution and energy dissipation capacity. The test results are compared to assess the previous damage effect and the retrofit technique's effectiveness. A final study is presented concerning the masonry unit and slenderness effect with other literature results.
- The maximum curvature reinfection thresholdPublication . Martins, José; Pinto, Alberto; Stollenwerk, Nico
- The word problem for κ-terms over the pseudovariety of local groupsPublication . Costa, J. C.; Nogueira, C.; Teixeira, M. L.In this paper we study the κ-word problem for the pseudovariety LG of local groups, where κ is the canonical signature consisting of the multiplication and the pseudoinversion. We solve this problem by transforming each arbitrary κ-term α into another one α∗ called the LG-canonical form of α and by showing that different canonical forms have different interpretations over LG. The procedure of construction of these canonical forms consists in applying reductions determined by a set Σ of κ-identities. As a consequence, Σ is a basis of κ-identities for the κ-variety generated by LG.