Browsing by Issue Date, starting with "2017-06"
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- Quality perception and chromatic changes in digital imagesPublication . Bernardo, Marco André Vieira Andrade; Sousa, Maria Manuela Areias da Costa Pereira de; Fiadeiro, Paulo TorrãoThe work presented in this thesis intends to provide significant contributions to the research and development on multimedia quality assessment. It is particularly focused on the evaluation of image quality perception and models, and also on the study of consumer sensitivity to induced chromatic changes in digital images. The main motivation is to evaluate the perception of quality, providing the means to improve the consumer immersion capability of new trends in imaging technology, a more realistic perception of the contents, and consequently to reach new levels of quality of experience. New representation models of visual information are being developed to offer visual fidelity closer to the human perceptual limits. Such representation models, like hyperspectral and multiexposure technologies, lead to new image formats that recently had acquired large attraction from scientific, professional, and artistic communities. The first research topic in this thesis reports a study on the induced chromatic changes effects on perceived colors in images and subsequent quality of experience influence on consumers. The results had demonstrated that subjects reveal larger perception to a loss of color naturalness than to the error magnitude itself. Moreover, the eye tracking data revealed a high correlation with the perceived image quality. The second research topic is devoted to the quality evaluation of the JPEG XT performance on high dynamic range images coding. This study, made in cooperation with other research groups inside Qualinet, benefit from the experience and knowledge acquired on the first research topic. Furthermore, allowed to apply the acquired knowledge on quality in standardization activities. The JPEG XT profiles were verified and the application of quality metrics for quality evaluation was studied. It was concluded that metrics specifically developed for high dynamic range images revealed to be reliable predictors. Moreover, good performance can also be archived with objective metrics developed for low dynamic range domain, when used on perceptual domains. This thesis is concluded with a final comment on the achieved results and possible future research and development directions.
- Influence-based motion planning algorithms for gamesPublication . Amador, Gonçalo Nuno Paiva; Gomes, Abel João PadrãoIn games, motion planning has to do with the motion of non-player characters (NPCs) from one place to another in the game world. In today’s video games there are two major approaches for motion planning, namely, path-finding and influence fields. Path-finding algorithms deal with the problem of finding a path in a weighted search graph, whose nodes represent locations of a game world, and in which the connections among nodes (edges) have an associated cost/weight. In video games, the most employed pathfinders are A* and its variants, namely, Dijkstra’s algorithm and best-first search. As further will be addressed in detail, the former pathfinders cannot simulate or mimic the natural movement of humans, which is usually without discontinuities, i.e., smooth, even when there are sudden changes in direction. Additionally, there is another problem with the former pathfinders, namely, their lack of adaptivity when changes to the environment occur. Therefore, such pathfinders are not adaptive, i.e., they cannot handle with search graph modifications during path search as a consequence of an event that happened in the game (e.g., when a bridge connecting two graph nodes is destroyed by a missile). On the other hand, influence fields are a motion planning technique that does not suffer from the two problems above, i.e., they can provide smooth human-like movement and are adaptive. As seen further ahead, we will resort to a differentiable real function to represent the influence field associated with a game map as a summation of functions equally differentiable, each associated to a repeller or an attractor. The differentiability ensures that there are no abrupt changes in the influence field, consequently, the movement of any NPC will be smooth, regardless if the NPC walks in the game world in the growing sense of the function or not. Thus, it is enough to have a spline curve that interpolates the path nodes to mimic the smooth human-like movement. Moreover, given the nature of the differentiable real functions that represent an influence field, the removal or addition of a repeller/attractor (as the result of the destruction or the construction of a bridge) does not alter the differentiability of the global function associated with the map of a game. That is to say that, an influence field is adaptive, in that it adapts to changes in the virtual world during the gameplay. In spite of being able to solve the two problems of pathfinders, an influence field may still have local extrema, which, if reached, will prevent an NPC from fleeing from that location. The local extremum problem never occurs in pathfinders because the goal node is the sole global minimum of the cost function. Therefore, by conjugating the cost function with the influence function, the NPC will never be detained at any local extremum of the influence function, because the minimization of the cost function ensures that it will always walk in the direction of the goal node. That is, the conjugation between pathfinders and influence fields results in movement planning algorithms which, simultaneously, solve the problems of pathfinders and influence fields. As will be demonstrated throughout this thesis, it is possible to combine influence fields and A*, Dijkstra’s, and best-first search algorithms, so that we get hybrid algorithms that are adaptive. Besides, these algorithms can generate smooth paths that resemble the ones traveled by human beings, though path smoothness is not the main focus of this thesis. Nevertheless, it is not always possible to perform this conjugation between influence fields and pathfinders; an example of such a pathfinder is the fringe search algorithm, as well as the new pathfinder which is proposed in this thesis, designated as best neighbor first search.
- Inflation candidates: from string theory to particles physicsPublication . Korumilli, Sravan Kumar; Moniz, Paulo Rodrigues Lima VargasCosmic inflation is the cornerstone of modern cosmology. In particular, following the Planck mission reports presented in 2015 regarding cosmic microwave background (CMB), there is an increasing interest in searching for inflaton candidates within fundamental theories and to ultimately test them with future CMB data. This thesis presents inflationary models using a methodology that can be described as venturing top-down or bottom-up along energy scales. In the top-down motivation, we study inflationary scenarios in string theory and supergravity (SUGRA), namely with (multiple) 3-forms, Dirac-Born-Infeld Galileon model, a string field theory setup and N = 1 SUGRA attractor models. In the bottom-up motivation, we construct a grand unified theory based inflationary model with an additional conformal symmetry and study not only inflation but also provide predictions related to particle physics. Our research work includes various classes of inflation driven by scalar fields under a canonical, non-canonical and induced gravity frameworks. All these models are consistent with Planck data, supported by key primordial cosmological parameters such as the scalar spectral index ns, the tensor to scalar ratio r, together with the primordial non-Gaussianities. Future probes aiming to detect primordial gravitational waves and CMB non-Gaussianities can further help to distinguish between them.
- Field location and player roles as constraints on emergent 1-vs-1 interpersonal patterns of play in footballPublication . Laakso, Timo; Travassos, Bruno; Liukkonen, J.; Davids, KeithThis study examined effects of player roles on interpersonal patterns of coordination that sustain decision-making in 1-vs-1 sub-phases of football in different field locations near the goal (left-, middle- and right zone). Participants were fifteen U-16yrs players from a local competitive amateur team. To measure interpersonal patterns of coordination in the 1-vs-1 dyads we recorded: (i) the relative distance value between each attacker and defender to the centre of the goal, and (ii), the relative angle between the centre of the goal, each defender and attacker. Results revealed how variations in field locations near the goal (left-, middle- and right-zones) constrained the relative distance and relative angle values that emerged between them and the goal. It reveals that relative position of the goal is a key informational variable that sustained participants' behaviours for dribbling and shooting. Higher values of relative distance and angle were observed in the middle zone, compared to other zones. Players' roles also constitute a constraint on the interpersonal coordination for dribbling and shooting. Additionally, it seems that players' foot preference constrains the dynamics of interpersonal patterns of coordination between participants, especially in left and right zones. The findings suggest that to increase participants' opportunities for action, coaches should account with field positions, players' roles and preference foot.
- Prevalence of asthma and allergies in 13–14-year-old adolescents from Luanda, AngolaPublication . Arrais, Margarete; Lulua, O.; Quifica, F.; Pinto, J. Rosado; Gama, Jorge; Barata, Luis TabordaSETTING: The few epidemiological studies on asthma and allergic diseases performed in Africa have shown that the prevalence of these diseases is high or increasing. No such studies have been performed in Angola. OBJECTIVE : To determine the prevalence of asthma and other allergic diseases in Angolan adolescents. DESIGN: This was a descriptive, observational, crosssectional study in the province of Luanda, Angola, using the International Study of Asthma and Allergies in Childhood study methodology in adolescents aged 13 and 14 years. Twenty-three (12%) public schools were randomly selected. Data were analysed using the Statistical Package for the Social Sciences version 22.0 software. RESULTS : A total of 3128 adolescents were included. The prevalence of asthma (wheezing in the previous 12 months) was 13.4%. The prevalence of rhinitis (sneezing, runny or blocked nose in the previous 12 months) was 27% and that of eczema (itchy skin lesions in the previous 12 months) was 20%; both were more prevalent in girls. Rhinitis was associated with a greater number of episodes of night cough in adolescents with asthma. Rhinitis and eczema, a split-type air conditioning system, and frequent intake (more than once per month) of paracetamol were associated with a higher risk of having asthma. CONCLUSION: Asthma and related allergic diseases are a public health problem in adolescents from Luanda. Preventive and control measures should be implemented.
- Capacidade de absorção e processos organizacionais de gestão do conhecimento: relações com a inovaçãoPublication . Costa, Vítor Manuel Valente da; Monteiro, Samuel José FonsecaThe present doctoral thesis, written in the field of work and organizational psychology, merges theoretical and empirical scientific papers, and aims to answer to research goals related with the theoretical and empirical exploration and analysis of the existent relationships between absorptive capacity, key knowledge management processes and organizational innovation. Moreover, the present work analyzes, both theoretically and empirically, the absorptive capacity’s construct dimensionality. The developed theoretical chapters allowed the creation of an integrative model, strengthening the link between knowledge management processes and the phases of absorptive capacity as well as framing organizational innovation as a consequent of key knowledge processes and the organizational capability of acquiring external knowledge and apply it to commercial ends, that is, its absorptive capacity. One hundred eleven respondents, from different organizations, from ten activity sectors, participated on an online survey that collected sociodemographic data of the key informant and the corresponding company. An absorptive capacity scale, as well as instruments to assess knowledge management processes – namely the key processes of acquisition, sharing, storage and documentation, and knowledge creation – and an organizational innovations scale were applied. The results, presented on the two empirical chapters, show that, on the surveyed companies, the organizational processes of knowledge acquisition and knowledge sharing reinforce absorptive capacity and new knowledge creation. Intra-organizational knowledge sharing also potentiates organizational innovation, though the mediating role of internal knowledge creation, variable that appears to be the strongest predictor of organizational innovation on the analyzed sample. Considering the results presented on chapter three and searching for more detailed knowledge on the variables that can promote internal knowledge creation, a model that reflects the interrelationships between potential absorptive capacity, the process of knowledge storage, and realized absorptive capacity was tested. The analysis showed that knowledge storage and the organizations’ realized absorptive capacity, that is, its ability to transform an apply previously acquired and assimilated knowledge, positively influence new knowledge creation and both, individually and conjointly, play a mediating role between potential absorptive capacity and the internal creation of new knowledge. Conclusions and final considerations are presented, with reflections about theoretical (for work and organizational psychology research) and practical (for the work and organizational psychologist) implications of the thesis, as well as its limitations.
- The effect of warm-up on sprinting kinematicsPublication . Morouço, Pedro; Gil, Maria Helena; Neiva, Henrique; Marques, MC; Sousa, António; Marinho, DanielThe purpose of this study was to verify the effects of warm-up on kinematic variables during short distance repeated sprints. Twenty-two college students randomly performed 2 x 30-m running time-trials after warm-up or with no warm-up, in different days. Performance (time-trial) and biomechanical (step length and step frequency) were assessed during both repeated trials. Performance was 0.5% faster after warm-up in the first 30-m time-trial (p = 0.03, d = 0.44), but without differences on step length and frequency. The second sprint was not different between conditions, but it was better than the first sprint in the no warm-up condition. This condition also led to higher changes between the first and second sprint. Thus, the warm-up is suggested to improve maximal running performances and maintaining kinematics more similar throughout the sprints.
- Paradigms for the management of the constructability of public buildings of higher educationPublication . Rei, João; Lanzinha, JoãoSeeks to provide a palpable understanding and perception of the underlying reasons for the lack of articulation between teaching, practice and the surrounding environment, to establish criteria and research methodologies that support leading to the establishment of an added value and reinforcement of the existing and strategic role and resources Planning structures, articulated uninterruptedly monitoring precautionary measures, creating integrated opportunities unique to the authentic needs of the environment where they are inserted. At present, we can analyze that there are several paradigms of physical university systems widely studied as teaching experiences, we highlight some as the University of Beira Interior, this illustrates the experience of a public university that managed to act positively on the social environment of the place; The experience arises between the historic center and the university city, both of which develop together through an Urban Plan supported by the municipal authorities to encourage the recovery and revitalization of the city center through the recovery and rationalization of university activity. The urban fabric of the city of Covilhã is marked by the presence of higher education institutions. Only the real estate assets of the University occupy 4% of its area, created in 1986, following the Polytechnic Institute (1973), and the University Institute of Beira Interior (1979), the initial pole extends through the Real Fábrica de Panos da Ribeira Of Goldra and incorporates the Wool Museum of the UBI, open to the public since 1996. UBI's strategy seems to us to be very interesting from the point of view of reuse and urban reconstruction, for the rehabilitation of the opportunities to recover old factory premises (Convent of St. ° António (rectory), the old factories of the Rat, the Rugs, the Manufacturing Company of the Wool (Pole II), the palaces Melo e Castro, and Mendes Veiga, the chapel of S Martin. Next to the Carpinteira river, already in the 90's and until 2004, the IV pole is developed. Pole III develops with the Faculty of Health Sciences and makes a total physical space of UBI of approximately 134 500 m2, with more than 5 thousand students, 32 degrees, 376 postgraduate students, 464 teachers and 408 employees In the conversion of unusual buildings, one of the most important benefits is the preservation of the "internal force", as well as all the processes related to its formation, from the choice, the manufacture of the building material, or the transport equipment. An architectural reconversion project will already be more environmentally friendly and sustainable than any new construction project and, at the same time, at more favorable costs, such as saving energy and materials. At a collective level, the adaptation of vacant buildings produces vitality, gives identity to centers with urban rehabilitation and a desirable and attractive visual diversity. Reusing a historic building enhances the quality of life in the surrounding area and, in parallel, keeps alive the collective memory of the city.
- Inspeção e avaliação da acústica em património religiosoPublication . Rodrigues, Fabiel G.; Lanzinha, João; Martins, Ana Maria TavaresO estudo da acústica em edificado é um tema complexo, uma vez que correlaciona parâmetros objetivos, como o Tempo de Reverberação (TR), com parâmetros subjetivos como o Envolvimento. Estes parâmetros definem a impressão geral da acústica no edifício e a sua adequação a determinada utilização. No entanto, a acústica correlaciona-se também com outros fatores importantes, intrínsecos à conceção do espaço. A análise acústica, se aplicada a locais de culto religioso, é bastante complexa, já que é condicionada não só pelas necessidades arquitetónicas, mas também de outras como a prática da liturgia. Esta questão é mais notória no caso da igreja católica, dado existir a necessidade de compatibilidade acústica para a inteligibilidade da palavra, devido à importância do sermão na liturgia; mas também à música e canto, que integram a cerimónia religiosa. Neste sentido, aborda-se a caraterização acústica destes espaços, com o objetivo de estabelecer bases para investigação científica futura neste domínio.
- Determination of aerobic and anaerobic power in elite taekwondo athletes through a sport specific testPublication . Rocha, Fernando Paulo Sebastião; Costa, Aldo Filipe Matos Moreira Carvalho da; Brito, João Paulo Reis Gonçalves Moreira deCurrently, the modern taekwondo in the sporting competitive side requires a high volume and almost constant training intensity throughout the sports season. The specific physical assessment test mode can monitor the athlete's training status, giving specific guidance for the development of training, in addition to being an indicator of recognized potential for the prevention and detection of overtraining. It turns out that taekwondo athletes are subjected to physical evaluations with nonspecific tests, without any transfer to the form to the technical gesture level, and also in respect of the effort characteristic during training and competition. Thus, the primary purpose of this thesis was to determine the concurrent validity of using two assessment protocols of aerobic and anaerobic fitness in taekwondo athletes. A sample consisted of 17 male subjects older than 17 years from the Portuguese taekwondo national team participated in this study. The Bandal Chagui technique was selected to integrate both physical assessment protocols running against a punching bag. The 20m shuttle run test and the Wingate 30-second protocol test were both used as a criterion for aerobic and anaerobic evaluation, respectively. The aerobic-specific test was based on the progressive test of maximum effort proposed by Sant´Ana and collaborators, having been rated the maximal oxygen uptake (VO2max). The anaerobic-specific test was based on a protocol for 30 seconds, where the athletes had to perform the maximum number of kicks (Bandal Chagui) and with maximum force against a punching bag. The impact force of Bandal Chagui technique was evaluated in both protocols through a piezoelectric sensor. Here are some of the key findings: (i) There was a correlation between the two aerobic tests; (ii) The model presented for estimating VO2max with a specific test explains 74% of the observed variability in VO2max; (iii) The anaerobic-specific test had a level of agreement with the Wingate test, conferring specificity for the evaluation of anaerobic fitness.