Polytechnic Institute of Porto
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An IEC 61499 Replication for Distributed Control Applications
No full textModern industrial environment control programs are distributed among several devices. The IEC 61499 standard
defines function blocks with which distributed control applications may be developed, and how these are interpreted and executed. Its functionality and the inherent support for dynamic reconfiguration provide the required infrastructure for Industry 4.0 and industrial IoT applications. However, by their distributed nature new challenges are posed, especially about how modes of failure are handled. To avoid system malfunctions and
breakdowns due to partial failures, the authors propose a new framework were the concept of replication can be applied maintaining internal state synchronised. This paper presents an example of how the replication framework on the FORTE IEC 6499 execution platform can be developed and voting strategies, along with the results obtained in the implementation with the standard communication SIFBs available on the Eclipse 4diacTM.info:eu-repo/semantics/publishedVersio
Methodology for manipulation of Karnaugh maps designing for pneumatic sequential logic circuits
No full textThis paper presents an alternative way to use the Karnaugh maps, which minimises logical conditions used for ON/OFF control, in either pneumatic and electro pneumatic circuits. In the last case, the methodology allows the control of the circuit through a programmable logic controller (PLC). In this kind of processes, controlling pneumatic cylinders is a problem that not only depends on the state of the information present but also in terms of knowledge of past actions. In practice, ensuring a series of sequential movements in an automatic cycle is to find the set of equations that should be executed to ensure the realisation of the desired sequence. It means therefore that the equations that will allow the movements of each cylinder are functions only of two types of input variables, the position of each cylinder and if necessary, memory variables. One of the major merits that arise from the use of the proposed method is the simplicity of obtaining electrical schematic command circuit. The proposed methodology ensures not only the desired sequential cycle, as well as the minimisation of the variables necessary for control commands.info:eu-repo/semantics/publishedVersio
The Impact of Implementing Hygiene and Safety Measures on Absenteeism—A Case Study in a Small Metallurgical Company
No full textThe absenteeism related to health and safety at work is a serious issue in the manufacturing process, and some industries can be dangerous work fields with a high level of accidents. It is important to understand what causes the accident and, if possible, apply standard procedures to minimize the risk of accidents and subsequent absenteeism.
This study aims to assess the impact of the implementation of occupa-tional health and safety procedures on company absenteeism. In the compa-ny where the study took place, most work accidents and absenteeism hap-pened in the production area, with workers who directly handle raw materi-als and machines.
As a result, an HSE manager was hired in order to reduce accidents by putting in place several hygiene and security measures and procedures. The results of these measures as well as absenteeism data were studied and con-clusions regarding company performance were drawninfo:eu-repo/semantics/publishedVersio
Characterization and Modeling of the Bicycle-Antenna System for the 2.4GHz ISM Band
No full textVehicular communication is rapidly becoming a standard reality, and precise models are necessary for accurate performance estimates. Alongside cars and trucks, smaller vehicles such as scooters and bicycles are also set to participate in V2X networking, but have received considerably less attention. In this work, we present an extensive characterization of the gain pattern of a bicycle and antenna system for the IEEE 802.11g standard. We measure the radiation patterns of the antenna of a commodity 2.4 GHz WiFi module mounted on six distinct positions on the body of six archetypal bicycles in an anechoic chamber. The RSSI sample set per angle and antenna position is characterized statistically and input into an empirical model of the gain pattern of the bicycle-antenna system. We define a bicycle-to-X propagation model that pairs the proposed bicycle-antenna gain and a log-distance shadowing path loss model, and conduct outdoor measurement campaign for evaluation. We observe that the gain model measured in chamber matches the measured RSSI at small distances, whereas at larger distances it provides less accuracy.info:eu-repo/semantics/publishedVersio
A Glimpse at Bicycle-to-Bicycle Link Performance in the 2.4GHz ISM Band
No full textBicycle-to-bicycle (Bi2Bi) communication can be implemented by well-established technologies in the 2.4GHz ISM band: IEEE 802.11, Bluetooth or IEEE 802.15.4. These technologies have distinct performance due to different physical and data link layers. In this paper, we characterize the mentioned 2.4 GHz-operating technologies over opportunistic links established between bicycles using commodity hardware. We find that, in Bi2Bi links, Blue-tooth, IEEE 802.11 at 24 Mbit/s, and IEEE 802.11 with automatic rate adaptation can communicate only in the immediate surroundings (under 15m of range), to maxima of 1.5 Mbit/s, 17 Mbit/s and 25 Mbit/s, respectively. IEEE 802.15.4 and IEEE 802.11 at 1 Mbit/s sustain connectivity up to 30 and 40 meters and peak transfer rates of 50 kbit/s and 800 kbit/s respectively. In addition, we observed that, in all measurement scenarios, link performance depended strongly on whether bicycles were approaching or moving away, rather than on whether one was at the front or back of the other.info:eu-repo/semantics/publishedVersio
LEAN and ergonomics: how to increase the productivity improving the wellbeing of the workers – a case study
No full textThe principles of Lean manufacturing, in addition to addressing the reduction of waste throughout manufacturing processes, are also highly concerned about the conditions that can favor the productivity of operators, which is achieved through their well-being while performing tasks. This work was elaborated with a view to the analysis of a production line capable of producing different electronic devices and which presented deficiencies in terms of operator ergonomics, demanding undesired and exhausting efforts, having as aim the elimination of such conditions. Thus, a detailed study of the movements carried out by the operators along the assembly line was elaborated, and possible solutions were considered to eliminate the situations that were perceived as more tiring and capable of generating health problems for the operators, when repeated several times. The study was successfully developed, and solutions were found that completely eliminated actions that required exaggerated efforts or unnecessary movements, clearly optimizing the assembly flow and the well-being of the operators in the line.info:eu-repo/semantics/publishedVersio
A Short Review on Smart Building Energy Resource Optimization
No full textMotivated by increasingly strict policies aiming to reduce the pollutants emission that contribute to the greenhouse gases effect and seeking the sustainability of the electricity sector, buildings have great potential to contribute to these goals. For accounting more than a third of the world's energy consumption and combining the growing incentive in Distributed Generation (DG) and the electric vehicle (EV) industry, smart buildings will be a key development in the years to come. In this way, this work presents an introduction to the linear programming (LP) optimization method and review the main works related to the scope of Smart Buildings (SB) energy resources optimization modeled as LP, with the objective to analyze different approaches taken to meet their goals.This work has received funding from FEDER Funds through COMPETE program and from National Funds through FCT under the project UID/EEA/00760/2019 and BENEFICE – PTDC/EEI-EEE/29070/2017info:eu-repo/semantics/publishedVersio
Optimal expansion planning considering storage investment and seasonal effect of demand and renewable generation
No full textA new era of cleaner distributed generators, like wind and solar, dispersed along the distribution network are gaining great importance and contributing to the environment and political goals. However, the variability and intermittency of those generators pose new complexities and challenges to the network planning. This research paper proposes an innovative stochastic methodology to deal with the expansion planning of large distribution networks in a smart grid context with high penetration of distributed renewable energy sources and considering the seasonal impact. Also, new power lines locations and types, the size and the location of energy storage systems are considered in the optimization. A distribution network with 180 buses located in Portugal considering high distributed generators penetration is used to illustrate the application of the proposed methodology. The results demonstrate the advantage of the stochastic model when compared with a deterministic formulation, avoiding the need for larger investments in new lines and energy storage systems.This work has received funding from the EU's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 641794 (project DREAM-GO); from FEDER Funds through COMPETE program; from National Funds through FCT under the project UID/EEA/00760/2019 and from the project PTDC/EEI-EEE/28983/2017 - CENERGETIC. Bruno Canizes is supported by FCT Funds through SFRH/BD/110678/2015 PhD scholarship.info:eu-repo/semantics/publishedVersio
A 2020 perspective on “Scalable modelling and recommendation using wiki-based crowdsourced repositories:” Fairness, scalability, and real-time recommendation
No full textWiki-based crowdsourced data sources generally lack reliability, as their provenance is not intrinsically marshalled. By using recommendation, one may arguably assess the reliability of wiki-based repositories in order to identify the most interesting articles for a given domain. In this commentary, we explore current trends in scalable modelling and recommendation methods based on side information such as the quality and popularity of wiki articles. The systematic parallelization of such profiling and recommendation algorithms allows the concurrent processing of distributed crowdsourced Wikidata repositories. These algorithms, which perform incremental updating, need further research to improve the performance and generate up-to-date high-quality recommendations. This article builds upon our previous work (Leal et al., 2019) by extending the literature review and identifying important trends and challenges pertaining to crowdsourcing platforms, particularly those of Wikidata provenance.info:eu-repo/semantics/publishedVersio
Hardware/Software Implementation Factors Influencing Ethernet Latency
No full textMinimum Cycle Time is a common performance indicator adopted to compare Real-Time Ethernet protocols. Though serving its purpose, Minimum Cycle Time excludes the delays inside the sending and receiving nodes, so it is insufficient to estimate the end-to-end latency. In this work, we describe some implementation possibilities of an Ethernet node in a System-on-Chip and present measurements of the delay to send/receive packets from/to the application layer. We chose different points in the software to make the measurement, so the results cover more use-cases. We found the Ethernet Lite Media Access Controller (MAC) to be faster than the hard MAC (GEM) and the Lightweight IP stack to add less than 2.2 μs. Finally, we show how a hardware accelerator can reduce the delay of high-priority packets by 1.4 μs.info:eu-repo/semantics/publishedVersio