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Background: The present work is related to a project developed in a company dealing with the security and communication systems, fire alarms, and electronic displays sector, located in the district of Aveiro. This work aims to improve the logistics flow of material reception in the warehouse of a company by using case study research methodology. Methods: Initially, there were too many queues at reception and high throughput times. The approach used to solve these problems was balancing the workstations, with the help of industrial simulation software (Arena®) and changing the existing layout, making the queues residual in order to reduce the throughput times. Results: Considerable savings were achieved with this approach in terms of operational costs. A reduction of the throughput time by 28% is reached and a reduced number of workstations is achieved, as well as a greater capacity to receive more material without the need for further investment. Conclusions: The changes in the layout allowed improvements at the ergonomic level and greater organization (5 S’s) at the workstations, thus having a positive impact on the employees’ working conditions.

In the last few decades, the fast technological development has caused high competitiveness among companies, encouraging a pursuit for strategies that allow them to gain competitive advantage, such as the monitoring of performance by using key performance indicators (KPIs). However, its selection process is complex since there are several KPIs available to evaluate performance and different relationships between them. To overcome this challenge, the use of a multiple criteria decision-making model (MCDM) was proposed, namely the analytic network process (ANP) through which a reduced number of them are prioritized. To identify which KPIs are suitable for the press cast and die manufacturing industry, a literature review was made, and 58 unique KPIs were identified. Thus, to validate the proposed methodology, a case study was carried out in an automotive press molding industry. With the implementation of the proposed ANP model it was possible to identify 9 KPIs that ensure the correct molding process monitoring, while being aligned with the Balanced Scorecard criteria. The results show that the proposed model is suitable for selecting KPIs for the molding industry. publishersversion published

This work was partially supported by the following entities: (L.J.N.) proMetheus-Research Unit on Energy, Materials and Environment for Sustainability-UIDP/05975/2020, funded by national funds through FCT-Fundacao para a Ciencia e Tecnologia; (R.G.) UNIDEMI-Research & Development Unit for Mechanical and Industrial Engineering-UIDB/00667/2020, funded by national funds through FCT-Fundacao para a Ciencia e Tecnologia; and (J.C.M.) GOVCOPP-Research Unit on Governance, Competitiveness and Public Policies-UID/CPO/04058/2019, funded by national funds through FCT-Fundacao para a Ciencia e Tecnologia. The biomass industry is growing due to the current search for greener and more sustainable alternatives to fossil energy sources. However, this industry, due to its singularity, presents several challenges and disadvantages related to the transportation of raw materials, with the large volumes that are usually involved. This project aimed to address this internal logistics situation in torrefied biomass pellets production with two different biomass storage parks, located in Portugal. The main park receives raw material coming directly from the source and stores it in large amounts as a backup and strategic storage park. The second park, with smaller dimensions, precedes the production unit and must be stocked daily. Therefore, a fleet of transport units with self-unloading cranes is required to help to unload the biomass at the main park and transport the raw material from this park to the one preceding the production unit. Thus, the main goal was to determine the dimensions of the fleet used in internal transportation operations to minimize the idle time of the transport units using a methodology already in use in the mining and quarrying industry. This methodology was analyzed and adapted to the situation presented here. The implementation of this study allows the elimination of unnecessary costs in an industry where the profit margins are low. publishersversion published

Currently, the search for alternative sources of energy is not only due to the scarcity of non-renewable sources, since these still have an availability capable of meeting actual consumption needs, but also due to the negative environmental impacts that its consumption presents. Thus, the use of biomass as a renewable and sustainable energy source is increasingly presented as an alternative that must be taken into account. Torrefaction is a conversion process that aims to improve the properties of biomass through its thermal decomposition at temperatures between 220 and 320 &deg, C. Torrefaction can be defined by several variables, which have an impact on the final quality of the torrefied biomass. Therefore, there is an increase in the number of studies involving this topic, in order to improve the production of biomass and its use as a renewable energy source, in addition to reducing the costs of this process. In this work, a protocol was developed for a laboratory test procedure to produce low-cost torrefied biomass samples using equipment that can present a cost reduction of around 90%. The samples were analyzed to prove the viability of the developed protocol. The results obtained agree with the current literature, also confirming the improvement of the biomass properties. This work can serve as a platform for the development of other technologies, such as gasification for the production of hydrogen from torrefied biomass.

The protection relay issues increase with the penetration of distributed generation (DG) units in distribution networks. Blind protection, sympathetic tripping and failure of reclosing are the frequent problems that are created by adding DG to the distribution networks. This research focuses on the impact of reclosers on overcurrent relay blind protection areas with DGs embedded in the distribution network. The protection blinding in overcurrent relays leads to a delay or non-tripping of the relay. The conventional solution for the blinding issue is to increase the sensitivity in the relay settings. The variation of relay settings may cause problems in the distribution network. This paper investigates the effect of reclosers on eliminating blind areas and improves the reliability in the presence of DG. In this way, possible blind points of the case study are detected, and recloser relays are then installed in appropriate locations. The case study is based on realistic data of a distribution network. The DG consists of two generators with a capacity of 4 MW. The simulation is performed in DIgSILENT software.

This paper introduces a new structure for single-phase Active Power Harmonics Filter (APHF) with the simple and low-cost controller to eliminate harmonics and its side effects on low voltage grid. The proposed APHF includes an accurate harmonic detector circuit, amplifier circuit to trap tiny harmonics, switching driver circuit for precise synchronization, and inverter to create injection current waveform, which is extracted from reference signal. The control circuits are based on electrostatic devices consist of Op-Amp circuits. Fast dynamic, simplicity, low cost, and small size are the main features of Op-Amp circuits that are used in the proposed topology. The aim is removing the all grid harmonic orders in which the proposed APF injects an appropriate current into the grid in parallel way. The proposed control system is smart enough to compensate all range of current harmonics. A prototype is implemented in the power electronics laboratory and it is installed as parallel on a distorted grid by the non-linear load (15 APeak-Peak) to verify the compensating of harmonics. The harmonics are compensated from THD% = 24.48 to THD% = 2.86 and the non-sinusoidal waveform is renovated to sinusoidal waveform by the proposed APHF. The experimental results show a good accurate and high-quality performance.

This study suggests a model to include a solar power system or photovoltaic system (PV) in the control of frequency by taking into account a percentage of the PV power production for back-up reserve. This is done by investigating two scenarios: PV contribution in (1) initial primary frequency control and (2) entire primary frequency control. As explained in section three, 10% power of the PV modules which receive more than 400 w/m2 irradiation is allocated for the power reserve. The power generation of photovoltaic systems depends largely on weather conditions which makes their output power associated with some degree of uncertainty. For this reason, in this paper, a PV system is considered along with conventional hydro and thermal units and they are modeled in MATLAB/Simulink (version 9.3, MathWorks, Natick, MA, USA) with the purpose of exploring the behavior of the intended method. In the next phase, for further studies, this system is extended to multi-area power systems including gas turbines. The resultsof the simulation demonstrated that the photovoltaic involvement in the control of frequency can successfully amend the frequency of the overall network. Not only it can decrease the overshoot and undershoot of the frequency response, it has the ability to improve the settling time as well, which helps the system reach the steady state easily and in shorter time. Specifically, the overshoot has reached nearly zero in both one area and two area systems and undershoot has declined up to 60% and 50% in the one area and two-area system, respectively. Considering settling time, while it had a negligible improvement in the one area system, it showed a remarkable enhancement in the two-area system, which improved from about 25 s to 6 s by using the proposed method. View Full-Text

Recently the circular economy has increasingly received attention worldwide due to the recognition that the security of the supply of resources and environmental sustainability are crucial for the prosperity of all the countries and businesses. G20 countries are stimulating the development of frameworks that enhance the circular economy and generally more sustainable production and consumption modes. In this context, this paper aims to suggest an index to assess the sustainability and the circularity of manufacturing companies. With this tenet, a Sustainable Circular Index (SCI) is proposed based on a five-phase framework. This index could support managers in assessing their level of sustainability and circularity and in implementing some practices that could improve the performances of their companies regarding these two topics. This index represents an important benchmarking tool for manufacturing companies to assess their sustainable and circular behavior and represents a guideline for managers.