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Publications

2021

Bringing Green Software to Computer Science Curriculum: Perspectives from Researchers and Educators

Authors
Saraiva, J; Zong, Z; Pereira, R;

Publication
ITiCSE (1)

Abstract
Only recently has the software engineering community started conducting research on developing energy efficient software, or green software. This is shadowed when compared to the research already produced in the computer hardware community. While research in green software is rapidly increasing, several recent studies with software engineers show that they still miss techniques, knowledge, and tools to develop greener software. Indeed, all such studies suggest that green software should be part of a modern Computer Science Curriculum. In this paper, we present survey results from both researchers' and educators' perspective on green software education. These surveys confirm the lack of courses and educational material for teaching green software in current higher education. Additionally, we highlight three key pedagogical challenges in bringing green software to computer science curriculum and discussed existing solutions to address these key challenges. We firmly believe that 'green thinking"and the broad adoption of green software in computer science curriculum can greatly benefit our environment, society, and students in an era where software is everywhere and evolves in an unprecedented speed.

2021

Towards an Elastic Lock-Free Hash Trie Design

Authors
Areias, M; Rocha, R;

Publication
2021 20TH INTERNATIONAL SYMPOSIUM ON PARALLEL AND DISTRIBUTED COMPUTING (ISPDC)

Abstract
A key aspect of any hash map design is the problem of dynamically resizing it in order to deal with hash collisions. In this context, elasticity refers to the ability to automatically resize the internal data structures that support the hash map operations in order to meet varying workloads, thus optimizing the overall memory consumption of the hash map. This work extends a previous lock-free hash trie design to support elastic hashing, i.e., expand saturated hash levels and compress unused hash levels, such that, at each point in time, the number of levels in a path matches the current demand as closely as possible. Experimental results show that elasticity effectively improves the search operation and, in doing so, our design becomes very competitive when compared to other state-of-the-art designs implemented in Java.

2021

Single-Phase Three-Wire Power Converters Based on Two-Level and Three-Level Legs Using a Space-Vector PWM-Based Voltage Balancing

Authors
Gehrke, BS; Jacobina, CB; de Sousa, RPR; da Silva, IRFMP; de Freitas, NB; Correa, MBD;

Publication
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS

Abstract
This article proposes four converters for interfacing a single dc power source and loads of a single-phase three-wire system. The topologies of the proposed converters are based on two-level (2L) and three-level neutral point clamped (NPC) legs. For regulating the dc-link capacitors of the NPC-based converters, a dc-link voltage-balancing technique is proposed to balance the neutral-point voltage using the space-vector pulsewidth modulation, considering the harmonic distortion of the output voltages and the semiconductor losses from an algorithm that defines the vector sequences to be applied. These characteristics make the proposed converters suitable for applications in microgrid employing dc distributed energy resources or ac power supply by adding ac-dc stage. The proposed converters are compared to a conventional 2 L converter from simulated results for evaluating the semiconductor losses in balanced and unbalanced load scenarios. Experimental results are presented to verify the effectiveness of the proposed voltage-balancing technique and to validate the converters.

2021

Entrepreneurial Ecosystems and Entrepreneurial Initiative: Building a Multi-Country Taxonomy

Authors
Pita, M; Costa, J; Moreira, AC;

Publication
SUSTAINABILITY

Abstract
The main goal of this article is to appraise the existence of different patterns of the Entrepreneurial Ecosystems, to identify its relationship with Entrepreneurial Initiative, and recommend entrepreneurship policies that may influence the growth of entrepreneurial action. Without evidence on entrepreneurial ecosystems landscape and what determinants stimulate entrepreneurship in a given environment, policies could become flawed and miss the target. To address research purposes, the analysis was performed using data extracted from the Global Entrepreneurship Monitor (GEM) Database carried out between 2010 and 2016. To ensure a longitudinal perspective, it was used a balanced panel approach followed by Logistic Regression estimations. The article offers a novel and systematic approach, the Entrepreneurial Ecosystem Taxonomy, to overcome a disaggregated perspective on entrepreneurial ecosystems, between individual and context levels. Empirical findings capture four different country profiles, based on two measures: Entrepreneurial ecosystems and entrepreneurial initiative. The results allow to compare the four groups and appraise significant disparities around entrepreneurship determinants, namely, the education factor. While education is commonly recognized as a positive influence on entrepreneurship, the results suggest a contradictory effect. The existence of differentiated profiles and its determinants points outs the importance of developing specific entrepreneurship policy packages attending group specificities.

2021

A RELEVÂNCIA DO PORTAL BASE, À LUZ DOS PRINCÍPIOS FUNDAMENTAIS DA CONTRATAÇÃO PÚBLICA E DO PROCEDIMENTO DE FORMAÇÃO DOS CONTRATOS PÚBLICOS EM PORTUGAL

Authors
Anjos Azevedo, P; Rua Carneiro, D;

Publication
Dereito: revista xurídica da Universidade de Santiago de Compostela

Abstract
Resumo Na formação e execução dos contratos públicos devem ser respeitados os princípios da legalidade, prossecução do interesse público, imparcialidade, proporcionalidade, boa-fé, tutela da confiança, sustentabilidade e responsabilidade, concorrência, publicidade e transparência, igualdade de tratamento e não-discriminação. O procedimento de formação de contratos constitui a sucessão ordenada de atos que concorrem para a formação, a conclusão e a produção de uma plena eficácia jurídica de um contrato público. O legislador define os momentos que constituem a tramitação do procedimento, numa lógica de transparência, garantindo a imparcialidade e a igualdade de tratamento e de acesso ao procedimento e a adequação procedimental. O objetivo principal do portal Base é divulgar informação sobre os contratos públicos celebrados em Portugal sujeitos ao regime do Código dos Contratos Públicos. Para dar cumprimento a este objetivo, o portal constitui-se como uma ferramenta tecnológica que centraliza, num espaço virtual, informações referentes à formação e execução dos contratos públicos. Palavras-Chave: Portal Base; princípios; contratação pública; procedimento; contratos públicos

2021

Entrepreneurial initiative in Islamic economics - the role of gender. A multi-country analysis

Authors
Costa, J; Pita, M;

Publication
JOURNAL OF ISLAMIC ACCOUNTING AND BUSINESS RESEARCH

Abstract
Purpose The entrepreneurial initiative is believed as being a prosperity engine. Islamic organizations are presently committed to promoting entrepreneurship to generate economic growth, provide job opportunities, reduce government centrality, enhance innovation and sustainable development. The purpose of this paper is to identify which factors affect Islamic entrepreneurial endeavors with particular emphasis on the role of gender. Additionally, how education, age, moral constraints, self-perception and social support will affect those entrepreneurial intentions based on Islamic principles. Once identified, policy actions will help to overcome extant gaps, reinforcing the entrepreneurial ecosystem. Design/methodology/approach Determinants of the entrepreneurial initiative will be appraised in the set Islamic countries present in the Global Entrepreneurship Monitor (GEM) data set from 2016. Following the Organization of Islamic Cooperation list, 14 countries were identified establishing a total sample of 36,407 individuals. Using a set of predictors included in the theoretical framework a statistical analysis was performed followed by logit estimations. The significance of explanatory variables such as gender, age and social context toward entrepreneurial propensity reinforced the importance of specific tools rather than broad policies. Findings An entrepreneurial propensity is affected by three branches of factors: individual characteristics, individual behavior and individual perceptions along with the economic environment. The analysis shows that holding equal conditions, Islamic women in the sample are less prone to start a business compared to their male counterparts. Knowing other entrepreneurial endeavors enhance the entrepreneurial initiative. Fearing failure unconstraint entrepreneurial projects, but the self-perception of skills strongly triggers these initiatives. Research limitations/implications The empirical analysis relates to the GEM database, and, as a consequence, only 14 countries were considered, but it covers 36,407 individuals whose representativeness cannot be statistically proved, however, due to sample dimension the robustness is granted. Second, the sample is sectional covering the 2016 year, as a consequence results may be classified as exceptional.Finally, other factors such as institutional and behavioral determinants were not considered, despite their theoretical importance, due to their absence in the database. Still, the empirical results reinforce the theoretical debate and offer robust evidence to build a policy package, adapted to the Islamic singularities. Practical implications Still, the empirical results reinforce the theoretical debate and offer robust evidence to build a policy package, adapted to the Islamic singularities. Originality/value The paper identifies gender differences in entrepreneurial propensity among Islamic economics. The potential enhancers of the entrepreneurial initiative are first put in theoretical terms followed by an empirical analysis, encompassing descriptive analysis and econometric estimations. The results allow identification of gender gaps, as well as other individual and context characteristics affecting entrepreneurial endeavors. Empirical evidence casts light on policymakers elaborating accurate policy packages fostering gender equality in entrepreneurship in Islamic economics, aiming to increase overall entrepreneurial activity and leveraging socio-economic development. Finally, the study addresses recommendations to overcome gender differences relating to entrepreneurial activity considering the singularities of the context.

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