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- Book of Abstracts of the First International Conference - Building Bridges in STEAM Education in the 21st CenturyPublication . Soares, Filomena Baptista; Lopes, Ana Paula; Pinto, Carla; Mendonça, JorgeThe International Conference BBC'22 aims to provide an opportunity for all academic and non-academics to share their personal experiences and projects, presenting their contributions and getting feedback from other attendees.
- The role of synaptic transmission in a HIV model with memoryPublication . Pinto, Carla; Carvalho, Ana R.M.We propose a mathematical model with memory for the dynamics of HIV epidemics, where two transmission modes, cell-to-cell and virus-to-cell, and drug resistance are considered. Systems with memory, or fractional order systems, have largely been applied to the modeling of several real life phenomena. Here, we consider a fractional model where the order of the non-integer derivative takes values in the interval [0.5, 1.0]. We prove the local and global stability of the disease-free equilibrium. We study the role of the cell-to-cell transmission probability on the dynamics of the model, and on the value of the reproduction number, R0, for distinct values of the fractional order derivative, α. Moreover, we show evidence of an improvement of HIV infected patients quality of life, due to the increase of the drug efficacy. In the end, important inferences are drawn.
- Use of Hands-on and Remote Lab with an Inquiry-Based Approach to Learn Statistics in EngineeringPublication . Zannin, Marcelo; Lima, Natércia; Pinto, CarlaPractical activities are an effective way to contextualize concepts and motivate students. This article reports on an innovative use of hands-on and remote labs in a theoretical course of Statistics for engineering undergraduates. The lecturer used an inquiry-based approach to center learning around students. The problems proposed revolved around basic concepts of circuit theory: how reliable are resistance values and how does a resistor behave in an electric circuit. Students collected data and learned statistics while attempted to address the problems. We report on two implementations done in 2017, at Universidade Federal de Santa Catarina (Brazil), where 68 students concluded the course. We investigated the effects of such strategy, analyzing assessment results, attendance and accesses to the remote lab. We also surveyed the lecturer and students on the methodology and the use of the remote lab. Our results show that students and lecturer had positive views on the experience and suggest that students felt motivated to collaborate and learn statistics. We also found correlation among grades in lab activities and final grades, which shows the hands-on activities had a positive impact on students' academic performance.
- Analyzing the Implementation of Lean Methodologies and Practices in the Portuguese Industry: A SurveyPublication . Pinto, Carla; Mendonça, Jorge; Babo, Lurdes; Silva, Francisco J. G.; Fernandes, José L. R.The mass production paradigm on which much of the industry was based has changed. The market is increasingly demanding, requesting diversity and products that are more and more adapted to personal wishes and requirements. This implies producing a greater diversity of products in smaller quantities. Competitiveness is enormous, which forces most companies to be truly effective and efficient, taking care of product quality, delivery time, and final cost. Lean methodologies have been a valuable aid in this field. The diversity of Lean tools has been shown to have answers to the most diverse challenges, and companies are aware of this, increasingly adopting methodologies and processes that aim to progressively reduce waste and adapting their production paradigm to what the market requires. This work intends to provide a vision, as global as possible, of the pathway of Lean implementation in the Portuguese industry. For this purpose, a survey was carried out with a significant sample of Portuguese industrial companies from a wide range of activity sectors. The data collected through the survey were treated statistically, and then a SWOT analysis of the results was performed, which provided a collection of precious information on the evolution of industrial companies in Portugal
- Pareto and Zipf laws for city size distributionPublication . Pinto, Carla; Lopes, A. M.; Tenreiro Machado, J. A.Pareto and Zipf distributions have been used in the modeling of distinct phenomena, namely in biology, demography, computer science, economics, amongst others. In this paper, it is presented a short review of applications of these distributions in city sizes.
- Forced van der Pol oscillator of complex orderPublication . Pinto, Carla; Tenreiro Machado, J. A.In this paper it is considered a complex order forced van der Pol oscillator. The complex derivative Dα±jβ, with α, β ∈ R+ is a generalization of the concept of integer derivative, where α = 1, β = 0. We compute amplitude and period values of the periodic solutions of the complex order forced van der Pol oscillator, for variation of distinct parameters such as forcing frequency, forcing amplitude and parameters α and β. We find interesting quasi-periodic motion for certain values of the forcing frequency. This type of behaviour is seen in the continuous forced van der Pol oscillator.
- Fractional model for malaria diseasePublication . Pinto, Carla; Tenreiro Machado, J. A.In this paper we study a fractional order model for malaria transmission. It is considered the integer order model proposed by Chitnis et al [1] and we generalize it up to become a fractional model. The new model is simulated for distinct values of the fractional order. Are considered two initial conditions and a set of parameter values satisfying a value of the reproduction number, R0, less than one, for the integer model. In this case, there is co-existence of a stable disease free equilibrium and an endemic equilibrium. The results are in agreement with the integer order model and reveal that we can extend the dynamical evolution up to new types of transients. Future work will focus on analytically prove some of the results obtained.
- Self-similarity in world economyPublication . Pinto, Carla; Lopes, A. M.; Tenreiro Machado, J. A.Self-similarity is a property of complex networks, commonly observed in many distinct areas of science. Many real networks are said to be ¸ Sscale-freeˇT since they show a power law behavior. In this paper, we focus in self-similarity of economical phenomena. For that purpose we analyze data and their corresponding statistical properties. We approximate data by trendlines, whose parameters are unequivocally related with each type of phenomenon.
- Double power law behavior in everyday phenomenaPublication . Pinto, Carla; Lopes, António M.; Tenreiro Machado, J. A.We study similar statistical properties observed in distinct real world data. In particular, we focus on the power law (PL) distribution. We nd that some data is well tted by a single PL distribution whereas other phenomena force the use of two distinct PLs. This behavior is similar in, a priori, unrelated phenomena, such as catastrophes (terrorism, earthquakes) and variables associated to man-made systems, such as distribution of the number of words in texts or of the number of hits received by websites.
- Complex order van der Pol oscillatorPublication . Pinto, Carla; Tenreiro Machado, J. A.In this paper it is considered a complex order van der Pol oscillator. A complex derivative D®§|¯, with ®; ¯ 2 R+ is a generalization of the concept of integer derivative, where ® = 1; ¯ = 0: By applying the concept of complex derivative, we obtain a high-dimensional parameter space. Amplitude and period values of the periodic solutions of the complex order van der Pol oscillator, are studied for variation of these parameters.