Polytechnic Institute of Porto
Repositório Científico do Instituto Politécnico do PortoNot a member yet
26471 research outputs found
Sort by
Conceção do modelo de negócio para uma empresa de comércio eletrónico B2B: deportugal.pt
No full textThe growing advance of technologies has led to their introduction in the organizational
context in an increasingly comprehensive way. Therefore, the importance given to
business models in order to adjust them to this new reality was growing in importance.
E-commerce business models also emerged, adapted to the specificities of this
increasingly common way of conducting commercial transactions using digital means.
This dissertation presents the conception of an instantiation of an e-commerce business
model, in the business to business (B2B) segment. This will allow, at a later stage, the
creation of an online platform for the sale of one hundred percent Portuguese products
with a regional focus, to be sold to Portuguese merchants abroad, such as smoked meats,
cheeses, olive oil, wine, and many others.
For the development of this research, the methodological basis was Design Science
Research (DSR). A literature review was made in which business models oriented to an
e-commerce context were analyzed. After analyzing the models proposed by several
authors, it was concluded that the most appropriate model for the study would be the one
presented by Kenneth C. Laudon and Carol Guercio Traver. In order to better understand
the problematic, a market study was done, through a questionnaire and interviews, which
served as a basis. These also served as the basis for the instantiation of the business model
for the B2B e-commerce company "deportugal.pt". Once the business model was
established, it was validated through an interview with a specialist in the area of
commerce, in a country of continental Western Europe, and was evaluated positively.O crescente avanço das tecnologias originou a sua introdução no contexto organizacional
de forma cada vez mais abrangente. Assim sendo, a importância dada aos modelos de
negócio de modo a ajusta-los a este nova realidade foi crescendo em importância.
Surgiram tambémos modelos de negócio de comércio eletrónico, adaptados às
especificidades próprias desta forma, cada vez mais comum, de realização de transações
comerciais utilizando meios digitais.
Esta dissertação apresenta a conceção de uma instanciação de um modelo de negócio de
comércio eletrónico, no segmento business to business (B2B). Este permitirá que à
posterior, seja possivel criar uma plataforma online, de venda de produtos cem por cento
portugueses com uma vertente regional, a serem vendidos a comerciantes portugueses no
estrangeiro, tais como fumeiro, queijos, azeite, vinho, e muitos outros.
Para o desenvolvimento desta investigação, teve-se como base metodológica a Design
Science Research (DSR). Foi feita uma revisão de literatura em que foram analisados
modelos de negócio orientados para um contexto de comércio eletrónico. Depois de serem
analisados os modelos propostos por vários autores, concluiu-se que o modelo mais
adequado para o estudo seria o apresentado por Kenneth C. Laudon e Carol Guercio
Traver. De modo a perceber melhor a problemática, foi feito um estudo de mercado,
através de um questionário e entrevistas, que serviram de base. Estas serviram ainda de
base para a instanciação do modelo de negócio à empresa de comércio eletrónico B2B
“deportugal.pt”. Feita a instanciação do modelo de negócio, esta foi validada através de
entrevista a um especialista na área do comércio, num país da Europa Ocidental
Continental, tendo sido avaliado de forma positiva
A Holistic Memory Contention Analysis for Parallel Real-Time Tasks under Partitioned Scheduling
No full textWhen adopting multi-core systems for safety-critical applications, certification requirements mandate bounding the delays incurred in accessing shared resources. This is the case of global memories, whose access is often regulated by memory controllers optimized for average-case performance and not designed to be predictable. As a consequence, worst-case bounds on memory access delays often result to be too pessimistic, drastically reducing the advantage of having multiple cores. This paper proposes a fine-grained analysis of the memory contention experienced by parallel tasks running on a multi-core platform. To this end, an optimization problem is formulated to bound the memory interference by leveraging a three-phase execution model and holistically considering multiple memory transactions issued during each phase. Experimental results show the advantage in adopting the proposed approach on both synthetic task sets and benchmarks.info:eu-repo/semantics/publishedVersio
Deep Reinforcement Learning for Real-Time Trajectory Planning in UAV Network
No full textIn Unmanned Aerial Vehicle (UAV)-enabled wireless powered sensor networks, a UAV can be employed to charge the ground sensors remotely via Wireless Power Transfer (WPT) and collect the sensory data. This paper focuses on trajectory planning of the UAV for aerial data collection and WPT to minimize buffer overflow at the ground sensors and unsuccessful transmission due to lossy airborne channels. Consider network states of battery levels and buffer lengths of the ground sensors, channel conditions, and location of the UAV. A flight trajectory planning optimization is formulated as a Partial Observable Markov Decision Process (POMDP), where the UAV has partial observation of the network states. In practice, the UAV-enabled sensor network contains a large number of network states and actions in POMDP while the up-to-date knowledge of the network states is not available at the UAV. To address these issues, we propose an onboard deep reinforcement learning algorithm to optimize the realtime trajectory planning of the UAV given outdated knowledge on the network states.info:eu-repo/semantics/publishedVersio
Scalable, energy-aware system modeling and application-specific reconfiguration of MPSocs with a type-2 fuzzy logic system
No full textThis paper demonstrates that interval type-2 Fuzzy Logic Systems (FLS’s) are suited to Multiprocessor System-on-a-Chip (MPSoC) design modeling because of their ability to handle the uncertainty associated with input parameters. This makes for a scalable modeling process, whereas prior usage of type-1 FLS’s for modeling inhibited scalability. Specifically, the paper proposes a type-2 Takagi Sugeno Kang (TSK) FLS for modeling MPSoCs built around a multicore processor with shared memory. The paper also presents a TSK FLS reconfiguration methodology in order to dynamically reduce the energy consumption of such a multiprocessor. Modeling of MPSoC’s by means of the type-2 TSK FLS was found to be effective in terms of a reduction in the Energy Delay Product when applied to five large-scale numerical processing applications on an MPSoC. In fact, experimental results show a significant reduction (by 87–93% across the applications) in the energy consumption of an MPSoC.info:eu-repo/semantics/publishedVersio
A morphological and electronic study of ultrathin rear passivated Cu(In,Ga)Se2 solar cells
No full textThe effects of introducing a passivation layer at the rear of ultrathin Copper Indium Gallium di-Selenide Cu(In,Ga)Se2 (CIGS) solar cells is studied. Point contact structures have been created on 25 nm Al2O3 layer using e-beam lithography. Reference solar cells with ultrathin CIGS layers provide devices with average values of light to power conversion efficiency of 8.1% while for passivated cells values reached 9.5%. Electronic properties of passivated cells have been studied before, but the influence of growing the CIGS on Al2O3 with point contacts was still unknown from a structural and morphological point of view. Scanning Electron Microscopy, X-ray Diffraction and Raman spectroscopy measurements were performed. These measurements revealed no significant morphological or structural differences in the CIGS layer for the passivated samples compared with reference samples. These results are in agreement with the similar values of carrier density (~8 × 1016 cm-3) and depletion region (~160 nm) extracted using electrical measurements. A detailed comparison between both sample types in terms of current-voltage, external quantum efficiency and photoluminescence measurements show very different optoelectronic behaviour which is indicative of a successful passivation. SCAPS simulations are done to explain the observed results in view of passivation of the rear interface.P.M.P. Salomé acknowledges the funding of Fundação para a Ciência e a Tecnologia (FCT) through the project IF/00133/2015. The European Union's Horizon 2020 research and innovation programme ARCIGS-M project (grant agreement no. 720887) is acknowledged. J. M. V. Cunha acknowledges the funding of Fundação para a Ciência e a Tecnologia (FCT) through the project PD/BD/142780/2018. J. P. Teixeira and J. P. Leitão acknowledge the funding of FCT through the project UID/CTM/50025/2013.info:eu-repo/semantics/publishedVersio
A robust ex vivo method to evaluate the diffusion properties of agents in biological tissues
No full textA robust method is presented for evaluating the diffusion properties of chemicals in ex vivo biological tissues. Using this method that relies only on thickness and collimated transmittance measurements, the diffusion properties of glycerol, fructose, polypropylene glycol and water in muscle tissues were evaluated. Amongst other results, the diffusion coefficient of glycerol in colorectal muscle was estimated with a value of 3.3 × 10-7 cm2 /s. Due to the robustness and simplicity of the method, it can be used in other fields of biomedical engineering, namely in organ cryoprotection and food industry.Ministry of Science and Higher Education of the Russian Federation, Grant/Award Number: 08‐08; Russian Foundation for Basic Research, Grant/Award Number: 17‐00‐00275 (17‐00‐00272); Portuguese Foundation for Science and Technology, Grant/Award Number: FCT‐UID/EQU/04730/2013info:eu-repo/semantics/publishedVersio
Impact of erythromycin on a non-target organism: Cellular effects on the freshwater microalga Pseudokirchneriella subcapitata
No full textThe increasing and indiscriminate use of antibiotics is the origin of their introduction in aquatic systems through domestic and livestock effluents. The occurrence of erythromycin (ERY), a macrolide antibiotic, in water bodies raises serious concerns about its potential toxic effect in aquatic biota (non-target organisms), particularly in microalgae, the first organisms in contact with aquatic contaminants. This study aimed to evaluate the possible toxic effects of ERY on relevant cell targets of the freshwater microalga Pseudokirchneriella subcapitata. Algal cells incubated with significant environmental ERY concentrations presented disturbance of the photosynthetic apparatus (increased algal autofluorescence and reduction of chlorophyll a content) and mitochondrial function (hyperpolarization of mitochondrial membrane). These perturbations can apparently be attributed to the similarity of the translational machinery of these organelles (chloroplasts and mitochondria) with the prokaryotic cells. P. subcapitata cells treated with ERY showed a modification of metabolic activity (increased esterase activity) and redox state (alteration of intracellular levels of reactive oxygen species and reduced glutathione content) and an increased biovolume. ERY induced an algistatic effect: reduction of growth rate without loss of cell viability (plasma membrane integrity). The present study shows that chronic exposure (72 h), at low (μg L-1) ERY concentrations (within the range of concentrations detected in surface and ground waters), induce disturbances in the physiological state of the alga P. subcapitata. Additionally, this work alerts to the possible negative impact of the uncontrolled use of ERY on the aquatic systems.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/ BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Manuela D.Machado gratefully acknowledges the post-doctoral grant from FCT (SFRH/BPD/72816/2010).info:eu-repo/semantics/publishedVersio
Sensitivity of freshwater and marine green algae to three compounds of emerging concern
No full textIn this study, the toxicity of three compounds of emerging concern (CEC) belonging to different classes [metolachlor (herbicide), erythromycin (antibiotic) and triclosan (antiseptic)], were evaluated and compared using the freshwater alga Pseudokirchneriella subcapitata and the marine alga Dunaliella tertiolecta. Toxicity assays were performed by exposing algal cells, in exponential phase of growth, to the toxicants for 72 h (P. subcapitata) or 96 h (D. tertiolecta). The toxicant concentrations that induced an inhibition of 50% of algal growth (EC50) of P. subcapitata or D. tertiolecta were 118 and 11.3 × 103 μg L−1 for metolachlor (MTC), 38 and 5.75 × 103 μg L−1 for erythromycin (ERT) and 27.1 and 93 μg L−1 for triclosan (TCS), respectively. Based on these EC50 values, it was possible to hierarchize (decreasing order) the toxicity of the CEC studied: TCS > ERT > MTC. The EC50 values achieved for P. subcapitata were between 3.4- and 151-fold lower than those observed with D. tertiolecta, which demonstrated the higher sensitivity of the freshwater alga comparatively to the marine alga. All 72 h-EC10 or 72 h-EC50 values determined in this study with P. subcapitata are within the concentration range of these pollutants described in the literature, in ground and surface waters, which underlines the significance of this alga in the ecotoxicity assessment of freshwaters.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte. Manuela D. Machado gratefully acknowledges the post-doctoral grant from FCT (SFRH/BPD/72816/2010).info:eu-repo/semantics/publishedVersio
Cleaner Production: Toward a Better Future
No full textThis book provides an overview of cleaner production, including how regulations have evolved, and presents a broad perspective on how it is being developed. Presenting several practical examples and applications of modern clean production technologies, it provides readers with ideas on how to extend these practices to other industry sectors in order to contribute to a better environment in the future.
The authors start from the initial concepts of how to implement new cleaner production systems, before collecting recent developments in the area and demonstrating practical ways in which the latest knowledge can be applied. It motivates readers to develop new ideas on how to improve manufacturing systems to save energy and generate less waste, and discusses strategies on how to save, reuse and adapt materials, as well as techniques to reduce the waste and pollution produced.
This book serves as a reference resource for industrial management engineers and researchers, and is also of interest to undergraduate and postgraduate students looking for insights into cleaner production in industry.info:eu-repo/semantics/publishedVersio
Incremental Hotel Recommendation with Inter-guest Trust and Similarity Post-filtering
No full textCrowdsourcing has become an essential source of information for tourists and tourism industry. Every day, large volumes of data
are exchanged among stakeholders in the form of searches, posts, shares,
reviews or ratings. Specifically, this paper explores inter-guest trust and
similarity post-filtering, using crowdsourced ratings collected from the
Expedia and TripAdvisor platforms, to improve hotel recommendations
generated by incremental collaborative filtering. First, the profiles of hotels and guests are created using multi-criteria ratings and inter-guest
trust and similarity. Next, incremental model-based collaborative filtering is adopted to predict unknown hotel ratings based on the multicriteria ratings and, finally, post-recommendation filtering sorts the generated predictions based on the inter-guest trust and similarity. The proposed method was tested both off-line (post-processing) and on-line (real
time processing) for performance comparison. The results highlight: (i)
the increase of the quality of recommendations with the inter-guest trust
and similarity; and (ii) the decrease of the predictive errors with the online incremental collaborative filtering. Thus, this work contributes with
a novel method, integrating incremental collaborative filtering and interguest trust and similarity post-filtering, for on-line hotel recommendation
based on multi-criteria crowdsourced rating streams.info:eu-repo/semantics/publishedVersio