Search results
1 – 10 of 33Suzana Paula Gomes Fernando da Silva Lampreia, José Fernando Gomes Requeijo, José António Mendonça Dias, Valter Martins Vairinhos and Patrícia Isabel Soares Barbosa
The application of condition-based maintenance on selected equipment can allow online monitoring using fixed, half-fixed or portable sensors. The collected data not always allow a…
Abstract
Purpose
The application of condition-based maintenance on selected equipment can allow online monitoring using fixed, half-fixed or portable sensors. The collected data not always allow a straightforward interpretation and many false alarms can happen. The paper aims to discuss these issues.
Design/methodology/approach
Statistical techniques can be used to perform early failure detection. With the application of Cumulative Sum (CUSUM) Modified Charts and the Exponentially Weighted Moving Average (EWMA) Charts, special causes of variation can be detected online and during the equipment functioning. Before applying these methods, it is important to check data for independence. When the independence condition is not verified, data should be modeled with an ARIMA (p, d, q) model. Parameters estimation is obtained using the Shewhart Traditional Charts.
Findings
With data monitoring and statistical methods, it is possible to detect any system or equipment failure trend, so that we can act at the right time to avoid catastrophic failures.
Originality/value
In this work, an electro pump condition is monitored. Through this process, an anomaly and four stages of aggravation are forced, and the CUSUM and EWMA modified control charts are applied to test an online equipment monitoring. When the detection occurs, the methodology will have rules to define the degree of intervention.
Details
Keywords
Sonia Pedro Sebastiao and Isabel Soares
The concept of environmental diplomacy appears associated with events (conventions) promoted between states and transnational organisations to discuss aspects related to…
Abstract
Purpose
The concept of environmental diplomacy appears associated with events (conventions) promoted between states and transnational organisations to discuss aspects related to regulating the use of natural resources and regulating pollution. In this study, the authors intend to highlight the contribution brought to environmental diplomacy by leading television figure David Attenborough and his focus on the destruction of biodiversity by humans (the problem). It is intended to analyse the frames of his public interventions, comparing them with the prevailing frames in the UNFCCC policies.
Design/methodology/approach
A predominantly inductive method of qualitative and interpretative nature is used. In epistemological terms, the framing analysis stems from a social constructivist perspective. A theoretical model for frame analysis was defined by combining the frameworks proposed by Entman (1993) and Semetko and Valkenburg (2000) and considering previous studies (Anholt, 2015; Seelig, 2019). Analysis scrutinised a two-fold corpus comprising articles regarding actions and statements by David Attenborough published in The Guardian between 2018 and 2020, and the UN's legal framework for climate change.
Findings
The most prominent frames regarding climate crisis in transnational policies are responsibilities. Attenborough's calls for action highlight the frames of “morality”, “responsibilities” and “problems”. However, it is necessary to make a distinction between the discourse used in transnational treaties and that by Attenborough. In the former, discourse is more technical and impersonal, presented in a structure of legal diplomas and barely accessible to the public. In contrast, Attenborough's speech is more emotional, appealing and sometimes dramatic. His message is transmitted straightforwardly to the public in a pedagogical, personal tone.
Social implications
The choice of high-profile personalities like David Attenborough as ambassadors has implications in the visibility of the environmental cause, and in the multiplication of initiatives that denounce environmental degradation.
Originality/value
This study explores and analyses the narrative construct regarding climate change as carried out by a trusted and respected media voice. The authors intend to contribute to understanding the amplification role of public figures in controversial issues and diplomatic matters. The main contribution of this study is to highlight the strategic nature of the choice of SDA by political powers to voice the drama of climate emergency.
Details
Keywords
Isabel Soares Silva and Renata Bastos
The purpose of this paper is to understand workers’ resistance toward change from a semi-continuous (SCW) to a continuous shift work system (CW), especially focusing the…
Abstract
Purpose
The purpose of this paper is to understand workers’ resistance toward change from a semi-continuous (SCW) to a continuous shift work system (CW), especially focusing the perspective of change and its impact on workers’ personal lives.
Design/methodology/approach
A case study was conducted at a Portuguese steel plant. A questionnaire was administered to 98 shift workers of the two systems, three focus groups (FG) each with ten CW workers, and three interviews with their managers.
Findings
The results of the FG and the interviews indicate the loss of days off during weekends as the main drawback of this change, leading to work schedule dissatisfaction. The consequences of the change focused on social and family life. For the CW workers, the conciliation between working hours and life outside the company were the only predictors of satisfaction with work schedule.
Research limitations/implications
The cross-sectional design is one of the main limitations, as well the use of only one organization in the study suggests future replication. Organizations need to consider the aspects of family and social life in the management of working hours.
Originality/value
Globally, this case study highlights the importance of family and social aspects in the adjustment process to working hours, especially when these involve performing work on the weekends, such as shift work.
Details
Keywords
Abstract
Details
Keywords
Patrícia Pereira da Silva and Isabel Soares
The aim of this paper is to assess the state of spot price convergence between several European electricity day‐ahead markets.
Abstract
Purpose
The aim of this paper is to assess the state of spot price convergence between several European electricity day‐ahead markets.
Design/methodology/approach
The concept of a fully integrated market is developed through the arbitrage relationship in which spot prices at one location should equal spot prices at another location plus the price of transmission. Accordingly, neighbouring markets are analysed to measure the relevance or their respective interconnecting and transmission constraints. Exploratory data approach is used and results are discussed, namely by correlation analysis.
Findings
This paper empirically shows that price differences have decreased during the analysed period, suggesting that integration between markets might be rising. The correlation analysis indicates very few relationships between these continental European power exchanges, what makes us to anticipate continuing difficulties in the building of a single electricity market. Nevertheless, there is some evidence for local integration and some price convergence. Only France and Germany appear to be relatively integrated with higher correlation coefficients, compared to the other cases. In respect to the other markets, this correlation analysis demonstrates that price variations in several locations do not affect prices in the neighbouring locations. Spain appears to be poorly integrated with the other locations as might be expected by its peripheral position and limited cross‐border transmission capacity.
Originality/value
The paper assesses electricity market integration in the context of European Union spot prices and industry structure.
Details
Keywords
Paulina Araújo Capela, Maria Sabrina Souza, Sharlane Costa, Jose C. Teixeira, Miguel Fernandes, Hugo Figueiredo, Isabel Delgado and Delfim Soares
In a printed circuit board assembly (PCBA), the coefficient of thermal expansion (CTE) mismatch between the solder joint materials has a detrimental impact on reliability. The…
Abstract
Purpose
In a printed circuit board assembly (PCBA), the coefficient of thermal expansion (CTE) mismatch between the solder joint materials has a detrimental impact on reliability. The mechanical stresses caused by the thermal changes of the assembly lead to fatigue and sometimes the failure of the solder joints. The purpose of this study is to propose a novel pad design to obtain an interrupted solder/substrate interface, to improve the PCBA reliability.
Design/methodology/approach
An interruption in the continuous intermetallic compound (IMC) layer of a solder joint was implemented, by the deposition of a silicone film in the pad, changing its geometry. That change allows a redistribution of stresses in the most ductile zone of the solder joint, the solder. The stress concentration at the solder/substrate interface is reduced, as well as the general state of stress at the solder joint.
Findings
A new way was developed to reduce the stress on the solder joints, caused by thermal variations, because of the different components CTEs mismatch. This new method consists of interrupting the IMC layers of the solder joint, strategically, redirecting the usual stresses to a more ductile area of the joint, the solder. This is an innovative method that allows increase the lifetime of PCBAs and the equipments.
Originality/value
In this study, a new pad design concept for higher solder joint reliability was developed to reduce the shear stress in the solder joints because of the CTE mismatch between all the solder joint components.
Details
Keywords
Delfim Soares, Manuel Sarmento, Daniel Barros, Helder Peixoto, Hugo Figueiredo, Ricardo Alves, Isabel Delgado, José C. Teixeira and Fátima Cerqueira
This study aims to investigate the effect of bismuth addition (up to 30 Wt%) on the microstructure and electrical conductivity of a commercial lead-free alloy (SAC405) near the…
Abstract
Purpose
This study aims to investigate the effect of bismuth addition (up to 30 Wt%) on the microstructure and electrical conductivity of a commercial lead-free alloy (SAC405) near the solder/substrate soldered joint. The system under study is referred in this work as (SAC405 + xBi)/Cu, as Cu is the selected substrate in which the solder was casted. The electrical resistivity of this system was investigated, considering Bi addition effect on the local microstructure and chemical composition gradients within that zone.
Design/methodology/approach
Solder joints between Cu substrate and SAC405 alloy with different levels of Bi were produced. The electrical conductivity along the obtained solder/substrate interface was measured by four-point probe method. The microstructure and chemical compositions were evaluated by scanning electron microscopy/energy dispersive spectroscopy analysis.
Findings
Two different electrical resistivity zones were identified within the solder interface copper substrate/solder alloy. At the first zone (from intermetallic compound [IMC] until approximately 100 μm) the increase of the electrical resistivity is gradual from the substrate to the solder side. This is because of the copper substrate diffusion, which established a chemical composition gradient near the IMC layer. At the second zone, electrical resistivity becomes much higher and is mainly dependent on the Bi content of the solder alloy. In both identified zones, electrical resistivity is affected by its microstructure, which is dependent on Cu and Bi content and solidification characteristics.
Originality/value
A detailed characterization of the solder/substrate zone, in terms of electrical conductivity, was done with the definition of two variation zones. With this knowledge, a better definition of processing parameters and in-service soldered electronic devices behavior can be achieved.
Details
Keywords
Francesco Tommasi, Andrea Ceschi, Riccardo Sartori, Marija Gostimir, Giulia Passaia, Silvia Genero and Silvia Belotto
The alignment between the labour market and initial vocational education and training (IVET) is placing always more importance on technical knowledge and skills, whilst…
Abstract
Purpose
The alignment between the labour market and initial vocational education and training (IVET) is placing always more importance on technical knowledge and skills, whilst metacognitive competences such as critical thinking and media literacy are increasingly neglected. In the context of IVET, this results in authors and practitioners paying always more attention to how to devise possible training interventions, with the double aim of implementing their educational pathways and enhancing students’ critical thinking and media literacy. This paper aims to report the state of the art concerning such processes of enhancement in IVET students.
Design/methodology/approach
The study adopted the method of systematic scoping review to address the research questions on how to enhance critical thinking and media literacy in the context of IVET.
Findings
The paper presents the analyses of the n = 19 contributions collected. Then, it proposes an initial conceptualization of the dimensions of critical thinking and media literacy. Moreover, by combining evidence from various contributions, the review proposes implications for educational practices and strategies. Around these pieces of knowledge, further avenues of research and practice are proposed.
Research limitations/implications
This study contributes to the literature on critical thinking and media literacy in the context of IVET by advancing initial comprehensive conceptualizations of the two dimensions. Moreover, the study advances initial practical implications for teachers and trainers for the development of training interventions.
Originality/value
The originality of the present review rests in its proposal of definitions of critical thinking and media literacy; moreover, it widens the discussion of practices on how to enhance such metacognitive competences. Indeed, the study identifies the teaching and training practices meant to enhance critical thinking and media literacy and proposes applied implications in the context of IVET.
Details