Análise computacional do desempenho de estratégia para o religamento controlado de linhas de transmissão

The search for mitigation solutions, with respect to the effects of overvoltages linked to the energization and reclosing maneuvers of transmission lines include a challenging subject with strong impact on the insulation coordination of electrical systems. Although the recognition of classical and commercial proposals to mitigate these phenomena, other possibilities are certainly still worthwhile highlighting and investigations. In this context, the present work is grounded in the exposure of the physical and mathematical foundations of a strategy based on controlled switchings, whose moments to the line reclosing are pre-programmed. The computational evaluation of the effectiveness of the methodology is made using the ATP simulator, which are studies in a typical electrical system subjected to the action of short-circuits fallowed by shutdowns and subsequent reclosing, under the action of technology here focused and lack thereof.

Uma abordagem baseada em filtragem colaborativa integrada a mapas de saliência para a recomendação de imagens

Nowadays, the amount of customers using sites for shopping is greatly increasing, mainly due to the easiness and rapidity of this way of consumption. The sites, differently from physical stores, can make anything available to customers. In this context, Recommender Systems (RS) have become indispensable to help consumers to find products that may possibly pleasant or be useful to them. These systems often use techniques of Collaborating Filtering (CF), whose main underlying idea is that products are recommended to a given user based on purchase information and evaluations of past, by a group of users similar to the user who is requesting recommendation. One of the main challenges faced by such a technique is the need of the user to provide some information about her preferences on products in order to get further recommendations from the system. When there are items that do not have ratings or that possess quite few ratings available, the recommender system performs poorly. This problem is known as new item cold-start. In this paper, we propose to investigate in what extent information on visual attention can help to produce more accurate recommendation models. We present a new CF strategy, called IKB-MS, that uses visual attention to characterize images and alleviate the new item cold-start problem. In order to validate this strategy, we created a clothing image database and we use three algorithms well known for the extraction of visual attention these images. An extensive set of experiments shows that our approach is efficient and outperforms state-of-the-art CF RS.

A nasalidade no dialeto quilombola do Norte de Minas: uma análise contrastiva baseada em corpus

This research investigated the nasality of vowels in the spontaneous speech of inhabitants of the quilombola communities of Brejo dos Crioulos and Poções (MG). As a theoretical framework, we based on the assumptions of Phonetics and Phonology, in renowned scholars on the investigation of nasality (CAGLIARI, 1977; CÂMARA JR., 1984, 2013; BISOL, 2013; ABAURRE; PAGOTTO, 1996; SILVA, 2015), with subsidies of the Corpus Linguistics. Its general goal was to investigate the occurrence of nasality, in the dialect of these quilombola communities, and their linguistic behavior, considering the linguistic factors that can interfere in the phenomenon. Specifically it was aimed to a) detect the occurrence of nasalized vowels with the help of the resources that the Corpus Linguistics provides (Praat and WorldSmith Tolls); b) discriminate the different types of occurring contexts of nasalized vowels; c) make quantitative and qualitative analyzes of the nasalized vowels in the study corpus; d) describe and analyze the behavior of nasalized vowels and; e) contrast the values of F1 and F2 of the oral and nasalized vowels. It was hypothesized that the nasality happens because it is conditioned by the nasal segment following the nasalized vowel - phonological process of “assimilation” - its position as the primary stress and grammatical category. It was believed that the quilombolas communities of Brejo dos Crioulos and Poções produce nasalized vowels in their speech and this linguistic phenomenon is favored by the adjacent presence of consonants or nasal vowels. Furthermore, it was hypothesized that the values of F1 and F2 of oral and nasalized vowels in these communities are distinct. The following research questions were elaborated: (i) is the presence of nasalized vowels in the speech of these quilombola communities conditioned to the presence of a nasal sound segment? (ii) does the nasal sound segment following the nasalized vowel favor the occurrence of the nasality phenomenon? is there a difference between the values of F1 and F2 of the oral and nasalized vowels in both quilombola communities considered? To compose our corpus, 24 interviews recordings were used (12 female speakers and 12 male speakers), a total of 24 participants. It was found that the following nasal sound segment tends to condition the nasalized vowel. In general, it assimilates the lowering of the soft palate of nasal consonant segment immediately following, but there are cases of nasal vowel segment - regressive assimilation; the stressed syllable tends to favor the nasality, but it occurs in pretonic and postonic position as well; F1 and F2 values of oral and nasalized vowels in the quilombola communities of Poções and Brejo dos Crioulos are distinct: the group of Brejo dos Crioulos tends to produce the F1 of oral and nasalized vowels more lowered than the group of Poções and the F2, in a more anterior position. The nasality tends to occur in verbs and nouns, although it is not specific to a grammatical category. This research found cases of spurious nasalization, confirming previous studies. In turn, it revealed cases of lexical items with favorable context for nasalization, but with its non-occurrence. This last case, considered as the lowering of the uniform soft palate in PB, presented pronounced vowels without the soft palate lowering. That is, it was detected variation in the phenomenon of nasalization in PB. With this work, it was promoted the discussion about nasality, in order to contribute to the linguistic studies about the functioning of Brazilian Portuguese in this geographical context.