Polytechnic Institute of Porto
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Lean Manufacturing: Implementation, Opportunities and Challenges
No full textThe paradigm of manufacturing is undergoing a major evolution throughout the world. The use of computers, the Internet and new challenges related to the Industry 4.0 have changed the way we engineer and manufacture products. Improving production with Lean Thinking is an evolution of a traditional approach in order to improve its processes to remain competitive in the global market.
Lean Manufacturing is a multidimensional approach that embraces a wide variety of management practices in a unified system. These practices contain, quality systems, team work, and supplier management, among others. Nowadays, other practices have been adopted such as human factors and ergonomics.
This book presents contributions of Lean Manufacturing applications in the world development and is intended to provide a comprehensive view of issues related to this area, with a specific focus on lean engineering principles; it is full of practical production examples of how Lean Thinking can be applied effectively to production systems.
This work was conceptualized for an audience of graduate students mainly; however, it can also be consulted by engineers and company managers who seek state-of-the-art applications on Lean Manufacturing within a wide diversity of scenarios and conditions.
The book, organized into 17 chapters, is intended to be an excellent source for dissemination of applied researches, lean concepts, and practices that have been successfully applied in the developing world domain. The book is also an excellent example of academy purpose with collaboration between different institutions from different countries that provide a global approach.info:eu-repo/semantics/publishedVersio
Online Velocity Control and Data Capture of Drones for the Internet of Things: An Onboard Deep Reinforcement Learning Approach
No full textApplications of unmanned aerial vehicles (UAVs) for data collection are a promising means to extend Internet of Things (IoT) networks to remote and hostile areas and to locations where there is no access to power supplies. The adequate design of UAV velocity control and communication decision making is critical to minimize the data packet losses at ground IoT nodes that result from overflowing buffers and transmission failures. However, online velocity control and communication decision making are challenging in UAV-enabled IoT networks, due to a UAV?s lack of up-to-date knowledge about the state of the nodes, e.g., the battery energy, buffer length, and channel conditions.info:eu-repo/semantics/publishedVersio
Chronic exposure of the freshwater alga Pseudokirchneriella subcapitata to five oxide nanoparticles: Hazard assessment and cytotoxicity mechanisms
No full textThe increasing use of nanoparticles (NPs) unavoidably enhances their unintended introduction into the aquatic systems, raising concerns about their nanosafety. This work aims to assess the toxicity of five oxide NPs (Al2O3, Mn3O4, In2O3, SiO2 and SnO2) using the freshwater alga Pseudokirchneriella subcapitata as a primary producer of ecological relevance. These NPs, in OECD medium, were poorly soluble and unstable (displayed low zeta potential values and presented the tendency to agglomerate). Using the algal growth inhibition assay and taking into account the respective 72 h-EC50 values, it was possible to categorize the NPs as: toxic (Al2O3 and SnO2); harmful (Mn3O4 and SiO2) and non-toxic/non-classified (In2O3). The toxic effects were mainly due to the NPs, except for SnO2 which toxicity can mainly be attributed to the Sn ions leached from the NPs. A mechanistic study was undertaken using different physiological endpoints (cell membrane integrity, metabolic activity, photosynthetic efficiency and intracellular ROS accumulation). It was observed that Al2O3, Mn3O4 and SiO2 induced an algistatic effect (growth inhibition without loss of membrane integrity) most likely as a consequence of the cumulative effect of adverse outcomes: i) reduction of the photosynthetic efficiency of the photosystem II (ФPSII); ii) intracellular ROS accumulation and iii) loss of metabolic activity. SnO2 NPs also provoked an algistatic effect probably as a consequence of the reduction of ФPSII since no modification of intracellular ROS levels and metabolic activity were observed. Altogether, the results here presented allowed to categorize the toxicity of the five NPs and shed light on the mechanisms behind NPs toxicity in the green alga P. subcapitata.This work was performed in the framework of the financing by Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit 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 and LAQV (UID/QUI/50006/2013—POCI/01/0145/FEDER/007265) with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020.info:eu-repo/semantics/publishedVersio
Congestion management in active distribution networks through demand response implementation
No full textDespite the positive contributions of controllable electric loads such as electric vehicles (EV) and heat pumps (HP) in providing demand-side flexibility, uncoordinated operation of these loads may lead to congestions at distribution networks. This paper aims to propose a market-based mechanism to alleviate distribution network congestions through a centralized coordinated home energy management system (HEMS). In this model, the distribution system operator (DSO) implements dynamic tariffs (DT) and daily power-based network tariffs (DPT) to manage congestions induced by EVs and HPs. In this framework, the HP and EV loads are directly controlled by the retail electricity provider (REP). As DT and DPT price signals target the aggregated nodal demand, the individual uncoordinated HEMS models operating under these price signals are unable to effectively alleviate congestion. A large number of flexible residential customers with EV and HP loads are modeled in this paper, and the REP schedules the consumption based on the comfort preferences of the customers through HEMS. The effectiveness of the market-based concept in managing the congestion is demonstrated by using the IEEE 33-bus distribution system with 706 residential customers. The case study results show that considering both pricing systems can considerably mitigate the overloading occurrences in distribution lines, while applying DTs without considering DPTs may lead to severe overloading occurrences at some periods.The present work was done and funded in the scope of the following projects: H2020 DREAM-GO Project (Marie Sklodowska-Curie grant agreement No 641794); AVIGAE Project (P2020 - 3401); UID/EEA/00760/2013 funded by FEDER, Spain funds through COMPETE program and by national funds through Fundação para a Ciência e a Tecnologia (FCT), Portugal; and SFRH/BD/94688/2013 (Mohammd Ali Fotouhi Ghazvini PhD grant).info:eu-repo/semantics/publishedVersio
Poster Abstract: Multi-Drone Assisted Internet of Things Testbed Based on Bluetooth 5 Communications
No full textIn this paper, a multi-hop airborne system is built based on Bluetooth 5 connected autonomous drones to relay real-time data of
Internet of Things (IoT). A new lightweight Onboard Bluetooth
Transceiver (OBT) is developed for reliable drone-to-drone and
drone-to-ground communications. A graphical user interface is
presented to monitor real-time flight trajectory of the drones and
end-to-end data delivery. Outdoor experiments are conducted in
real world to test autonomous flight control of the drones and
received signal strength of the OBT communications.info:eu-repo/semantics/publishedVersio
MAC-PHY Cross-layer design for Secure Wireless Avionics Intra-Communications
No full textThis paper presents a framework for medium access control (MAC) and physical (PRY) cross-layer security design of wireless avionics intra-communications (WAICs). The paper explores the different options based on the latest results of MAC-PRY cross-layer design and the available standard technologies for WAICs. Particular emphasis is given to solutions based on multiple-input multiple-output (MIMO) systems and recent developments towards a wireless technology with ultra-low latency and high reliability in the context of 5G and machine-type traffic support. One major objective is to improve WAICs technology and thus match the real-time, reliability and safety critical performance of the internal aeronautics bus technologies (e.g., ARINC 664). The main identified vulnerabilities and potential solutions are explored, as well as their impact on system design complexity and feasibility for wireless networks on-board aircraft. The solutions are presented in the context of the European project SCOTT (secure connected trustable things) using the recently released reference architecture for trusted IoT systems. Other aspects of SCOTT such as trust, privacy, security classes, and safety are also discussed here for the aeronautics domain.info:eu-repo/semantics/publishedVersio
Mobile fog computing security: A user-oriented smart attack defense strategy based on DQL
No full textEach fog node interacts with data from multiple end-users in mobile fog computing (MFC) networks. Malicious users can use a variety of programmable wireless devices to launch different modes of smart attacks such as impersonation attack, jamming attack, and eavesdropping attack between fog servers and legitimate users. The existing research in MFC lacks in the contributions of defense of smart attack and also requires in the discussions of subjective decision making by participants. Therefore, we propose a smart attack defense scheme for authorized users in MFC in this paper. First, we construct a static zero-sum game model between smart attackers and legitimate users based on prospect theory. Second, the double Q-learning (DQL) is proposed to restrain the attack motive of smart attackers in the dynamic environment. The proposed DQL method generates the optimum defense choice of legitimate users against smart attacks so that they can efficiently determine whether to use only physical layer security (PLS) to avoid those smart attacks. We use our scheme to contrast with the basic schemes, i.e., Q-learning scheme, the Sarsa scheme, and the greedy strategy. Experiment results prove that the proposed scheme can enhance the utility of legitimate users, restrain the attack motive of smart attackers, and further provide better security protection in the MFC environment.info:eu-repo/semantics/publishedVersio
A Multi-Ray Analysis of LOS V2V Links for Multiple Antennas with Ground Reflection
No full textThis paper presents a vehicle-to-vehicle (V2V) geometric multi-ray tracing model for an improved line-of-sight (LOS) estimation. The model is especially suited for distributed antenna transceivers in the presence of ground reflections. The multiple antennas are assumed to be spaced regularly in horizontal and vertical directions over contiguous vehicles. The main focus of our study is the ability of the multiple antenna system to counteract or exploit, respectively, the destructive or constructive interference of multiple rays in the LOS channel component. This work is a complement to existing V2V channel models by providing more details on how ground reflections affect the LOS channel. The analysis is initially framed in the context of MIMO (multiple-input multiple-output) systems to investigate general aspects such as capacity limits and singular value distribution. The work then focuses on a scheme with single symbol repetition across the transmit antennas and two different strategies for signal combining at the receiver: maximum-ratio and equal-gain combining (MRC and EGC, respectively). These solutions are compared with a full diversity solution as well as with the information theoretical limits. An adaptive antenna selection mechanism is finally proposed that outperforms all other solutions. The paper shows both vertical and horizontal polarization results with corrected complex Fresnel reflection coefficients for lossy materials. Moreover, it is shown that multiple antenna design in V2V systems can be useful to counteract the destructive interference created by multiple rays on the LOS channel component.info:eu-repo/semantics/publishedVersio
Moving tissue spectral window to the deep‐ultraviolet via optical clearing
No full textThe optical immersion clearing technique has been successfully applied through the last 30 years in the visible to near infrared spectral range, and has proven to be a promising method to promote the application of optical technologies in clinical practice. To investigate its potential in the ultraviolet range, collimated transmittance spectra from 200 to 1000 nm were measured from colorectal muscle samples under treatment with glycerol-water solutions. The treatments created two new optical windows with transmittance efficiency peaks at 230 and 300 nm, with magnitude increasing with glycerol concentration in the treating solution. Such discovery opens the opportunity to develop clinical procedures to perform diagnosis or treatments in the ultraviolet.L.O. and V.T. have contributed equally to this work. The work was supported by the Portuguese grant FCTUID/
EQU/04730/2013. V.T. was supported by RF Governmental grant 14.W03.31.0023.info:eu-repo/semantics/publishedVersio
Nickel Oxide Nanoparticles Trigger Caspase- and Mitochondria-Dependent Apoptosis in the Yeast Saccharomyces cerevisiae
No full textThe expansion of the industrial use of nickel oxide (NiO) nanoparticles (NPs) raises concerns about their potential adverse effects. Our work aimed to investigate the mechanisms of toxicity induced by NiO NPs, using the yeast Saccharomyces cerevisiae as a cell model. Yeast cells exposed to NiO NPs exhibited typical hallmarks of regulated cell death (RCD) by apoptosis [loss of cell proliferation capacity (cell viability), exposure of phosphatidylserine at the outer cytoplasmic membrane leaflet, nuclear chromatin condensation, and DNA damage] in a process that required de novo protein synthesis. The execution of yeast cell death induced by NiO NPs is Yca1p metacaspase-dependent. NiO NPs also induced a decrease in the mitochondrial membrane potential and an increase in the frequency of respiratory-deficient mutants, which supports the involvement of mitochondria in the cell death process. Cells deficient in the apoptosis-inducing factor ( aif1Δ) displayed higher tolerance to NiO NPs, which reinforces the involvement of mitochondria in RCD by apoptosis. In summary, this study shows that NiO NPs induce caspase- and mitochondria-dependent apoptosis in yeast. Our results warn about the possible harmful effects associated with the use of NiO NPs.This work was performed in the framework of the financing by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of the UID/BIO/04469/2013 unit, 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 Norte2020Programa Operacional Regional do Norte and LAQV (UID/QUI/50006/2013-POCI/01/0145/FEDER/007265) with financial support from FCT/MEC through national funds and cofinanced by FEDER, under Partnership Agreement PT2020.
C.A.S. gratefully acknowledges the doctoral grant (SFRH/BD/101452/2014) from FCT.info:eu-repo/semantics/publishedVersio