Revisão conceptual, enquadramento e competências nucleares

O estudo da liderança e competências associadas são temáticas que despertam elevado interesse nas organizações e no mundo académico. As competências de liderança em contexto organizacional reúnem um conjunto de aptidões e comportamentos que contribuem para desempenhos superiores. A abordagem conjugada dos conceitos de liderança e de competência permite às organizações identificar e desenvolver líderes, definindo e comunicando os requisitos de liderança. Este estudo baseou-se numa estratégia mista, conjugando questionários, entrevistas e pesquisa bibliográfica. O objetivo geral consistiu em identificar as competências nucleares dos líderes operacionais do Exército Português, recorrendo para o efeito, ao modelo de competências nucleares do Exército Norte-Americano. Apurámos que a esmagadora maioria das competências nucleares é aplicável. Face ao modelo apresentado que deverá ser testado em contexto organizacional, sugerimos a eventual inclusão de outros modelos. Aconselhamos uma mudança do paradigma da gestão tradicional de recursos humanos funcional, para um modelo baseado em competências. Abstract: The study of leadership and associated competencies are subjects that have aroused interest of organisations and general academic world. In the organisational context, leadership competencies gather a set of skills and behaviours that contribute to superior performance. This joint approach of leadership and competence concepts allows organisations to identify and develop leaders, by setting and communicating leadership requirements. This study was based on a hybrid strategy, combining questionnaires, interviews and bibliographic research. The main purpose was to identify the core competencies of the Portuguese Army operational leaders, by resorting to the United States Army leadership core competencies framework. The research results point that the overwhelming majority of the core competencies are valid. The core competencies framework should be tested and other models might be included as necessary. We recommend a shift on the human resources classic management model towards a new framework based on competencies.N/

FATORES RELACIONADOS COM A PREVALÊNCIA DE LESÕES POR PRESSÃO EM CONTEXTO COMUNITÁRIO

Objetivo: identificar fatores relacionados com a prevalência de lesões por pressão. Método: estudo descritivo-correlacional, transversal, com usuários adultos dependentes em contexto comunitário. Os dados foram coletados em um formulário, mediante consulta de documentação no Sistema de Informação SClínico. No tratamento de dados foi utilizado o Statistical Package for the Social Sciences. Resultados: do total da amostra (n=771), a maioria era do sexo feminino (68,2%) e pertencia à faixa etária de 85 anos ou mais (45,1%). A maioria apresentava Alto Risco de desenvolver lesão por pressão (52,1%). A prevalência foi de 11,2%, diferindo significativamente entre as categorias do Grau de Risco e a dimensão Mobilidade da escala de Braden (X2:p<0,000). Conclusão: identificados fatores relacionados com a prevalência da lesão por pressão, entre os quais o Grau de Risco e a dimensão mobilidade.Descritores: Lesão por Pressão. Adulto. Diagnóstico. Saúde Pública. Enfermagem em Saúde Comunitári

An investigative study into the sensitivity of different partial discharge φ-q-n pattern resolution sizes on statistical neural network pattern classification

This paper investigates the sensitivity of statistical fingerprints to different phase resolution (PR) and amplitude bins (AB) sizes of partial discharge (PD) φ-q-n (phase-amplitude-number) patterns. In particular, this paper compares the capability of the ensemble neural network (ENN) and the single neural network (SNN) in recognizing and distinguishing different resolution sizes of φ-q-n discharge patterns. The training fingerprints for both the SNN and ENN comprise statistical fingerprints from different φ-q-n measurements. The result shows that there exists statistical distinction for different PR and AB sizes on some of the statistical fingerprints. Additionally, the ENN and SNN outputs change depending on training and testing with different PR and AB sizes. Furthermore, the ENN appears to be more sensitive in recognizing and discriminating the resolution changes when compared with the SNN. Finally, the results are assessed for practical implementation in the power industry and benefits to practitioners in the field are highlighted

The transition towards a sustainable energy system in Europe: What role can North Africa's solar resources play?

Securing energy supply and speeding up the transition towards a reliable, sustainable, low-carbon energy system are among the major current and future challenges facing Europe. Importing dispatchable solar electricity from North Africa is considered as a potential and attractive option. Nevertheless, as things currently stand, the European Commission focuses mainly on the exploitation of the existing wind power potential in the North Sea, largely ignoring the solar power potential in the Sahara region of North Africa. After discussing the major challenges and issues facing Europe to achieve the assigned ambitious objectives, the paper emphasises the importance of North Africa's solar resources in helping Europe to successfully address the challenge of decarbonising its electricity system, in particular with regards to the security of supply and sustainability. Within these two major challenges, the paper explores the issues of access, barriers and opportunities. The paper highlights why the EU’s energy and climate goals will not be achievable without adequate grid expansion and grid-scale energy storage facilities, as well as other innovative measures to manage demand and ensure a secure energy supply. In this respect, the paper shows how the import of dispatchable electricity from North Africa via specific HVDC links could play a key role in helping the EU achieve its energy targets in a cost effective way without recourse to significant investments in transmission infrastructure and storage facilities. The paper then attempts to identify and analyze the main barriers that continue to inhibit the export of solar electricity from North Africa to Europe. Finally, to make the project more attractive and achievable in the near future, the paper proposes a systematic approach for setting up energy import scenarios. A promising import scenario is presented where energy import via Italy is shown to be a more viable and effective solution than via Spain.Peer reviewe

An Improved On-line Contingency Screening for Power System Transient Stability Assessment

peer reviewedThis paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases the simulation can be terminated after a few hundred milliseconds of simulated system response. The method’s outcome is an assessment of the system’s stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus system. A novel island detection approach, appropriate for an on-line application since it utilizes efficient algorithms from graph theory and enables stability assessment of individual islands, is also introduced. The New England and New York system as well as the large-scale model of the Continental-European interconnected system are used to test the proposed method with respect to assessment accuracy and computation time

Performance of wide-area power system stabilizers during major system upsets: investigation and proposal of solutions

© 2021 Springer Nature Switzerland AG. This is a post-peer-review, pre-copyedit version of Benasla, M., Denaï, M., Liang, J. et al. Performance of wide-area power system stabilizers during major system upsets: investigation and proposal of solutions. Electr Eng (2021). The final authenticated version is available online https://doi.org/10.1007/s00202-020-01168-3Wide-area damping controllers (WADCs) are effective means of improving the damping of inter-area oscillations and thereby ensuring a secure operation of modern highly stressed interconnected power systems; however, their implementation costs are high. Therefore, the controller must be well configured and designed to ensure its cost-effectiveness. Several techniques have been proposed in the literature to design effective controllers and good results have been achieved. However, some important practical aspects that could potentially impact the performance of the designed controller have not been addressed or studied in sufficient detail in these previous works. One such aspect is assessing the performance of the designed controllers under major system upsets resulting in large deviations in the frequency and fluctuations in the power. These may lead to controller saturation which could negatively impact its damping performance or even cause instability. In this paper, the impact of such large upsets is investigated on several test systems via extensive small- and large-signal analyses and it is shown that, during severe transients, controller saturation may occur and persist over a long period of time, posing a potential threat to the power system stability. This paper presents a very effective solution to alleviate this problem and help design more robust WADCs. The simulation results show that the proposed solution works well and leads to improved power system stabilisers performance during transient upsets.Peer reviewedFinal Accepted Versio

Estimation of stresses in atmospheric ice during aeolian vibration of power transmission lines

Aeolian vibration in bare and iced cable was simulated using the theory of cable vibration. High frequency vibration creates stresses in the cable and consequently in the ice covering that cable, which may result in ice failure and eventually ice shedding. These stresses were estimated in this study. Displacement of the cable during vibration was determined; furthermore, instantaneous wind loads in vertical and transverse directions, additional stresses induced by the motion in the cable and in the atmospheric ice, as well as torque due to cable springback were calculated. In order to simulate the loading conditions of a chunk of atmospheric ice in the middle of a span, a new model was developed using ABAQUS. Results from this model show in spite of high frequency vibration, the resulting level of stress in atmospheric ice is far less than its failure limit. In other words, the atmospheric ice under the condition assumed in this investigation does not shed due to aeolian vibration