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Visual analysis of temporal networks comprises an effective way to understand the network dynamics, facilitating the identification of patterns, anomalies, and other network properties, thus resulting in fast decision making. The amount of data in real-world networks, however, may result in a layout with high visual clutter due to edge overlapping. This is particularly relevant in the so-called streaming networks, in which edges are continuously arriving (online) and in non-stationary distribution. All three network dimensions, namely node, edge, and time, can be manipulated to reduce such clutter and improve readability. This paper presents an online and nonuniform timeslicing method, thus considering the underlying network structure and addressing streaming network analyses. We conducted experiments using two real-world networks to compare our method against uniform and nonuniform timeslicing strategies. The results show that our method automatically selects timeslices that effectively reduce visual clutter in periods with bursts of events. As a consequence, decision making based on the identification of global temporal patterns becomes faster and more reliable.

Temporal networks have been used to map the structural evolution of social, technological, and biological systems, among others. Due to the large amount of information on real-world temporal networks, increasing attention has been given to issues related to the visual scalability of network visualization layouts. However, visual clutter due to edge overlap remains the main challenge calling for efficient methods to improve the visual experience. In this paper, we propose a novel and scalable node reordering approach for temporal network visualization, named Community-based Node Ordering (CNO), combining static community detection with node reordering techniques to enhance the identification of visual patterns. The perception of trends, periodicity, anomalies, and other temporal patterns, is facilitated, resulting in faster decision making. Our method helps not only the study of network activity patterns within communities but also the analysis of relatively large networks by breaking down its structure in smaller parts. Using CNO, we further propose a taxonomy to categorize activity patterns within communities. We performed a number of experiments and quantitative analyses using two real-world networks with distinct characteristics and showed that the proposed layout and taxonomy speed up the identification of patterns that would otherwise be difficult to see.

The COP 21 (21st Conference of Parties) held in 2015, in Paris, proposed to limit the average global temperature increase at a maximum of 2 °C. Brazil has programs for reducing GHGs through Intended Nationally Determined Contributions (INDC) in the energy sector. Between 2012 and 2015 Brazil faced a drastic reduction in rainfall volumes which led to a decrease in hydroelectric generation, then offset by thermoelectric generation, with an increase in its emissions. The objective herein is to review the expansion in the use of renewable energy sources to meet the INDC's goals, given the future vulnerability of the Brazilian electricity matrix. The use of renewable energy such as wind, solar and co-generation for electric production has grown considerably in Brazil. The growth of wind power generation was a result of the investment initiated by these public policies to promote the Brazilian wind industry through the Programme of Incentives for Alternative Electricity Sources (PROINFA), the increase of wind generation in both South and Northeast subsystems. Wind energy is aimed to reach 20 GW of electricity production by 2024. The public and private initiatives in the solar energy segment reflect, first and foremost, upon the creation of a solar photovoltaic industry in the country and, from there, a consequent expansion of this energy's usage. The cogeneration processes have contributed to industries in a positive way, both in supplying electricity for internal energy plants' demands as well as those of the national electric system. Therefore, the diversification of the energy matrix is a goal to be achieved. The use of new renewable energy sources and the maintenance of investments in hydropower are part of the Brazilian strategy to turn its electric matrix less vulnerable climate change consequences..