Papers by Celso Alberto Saibel Santos
Este artigo análisa o desempenho dos algoritmos de roteamento determinístico e adaptativo em sist... more Este artigo análisa o desempenho dos algoritmos de roteamento determinístico e adaptativo em sistemas multicomputadores baseados em malhas tridimensionais, sob vários padrões de tráfego. Para realizar este estudo foi desenvolvido um simulador denominado SIM3D. Os resultados obtidos nas simulações são comparados considerando-se a latência e o throughput. Entre os fatores utilizados na avaliação do desempenho temos: o tipo de algoritmo de roteamento, o padrão de tráfego e o tamanho das mensagens.
A idéia central deste trabalho é demonstrar que a política de seleção de saída dos canais tem inf... more A idéia central deste trabalho é demonstrar que a política de seleção de saída dos canais tem influência direta na latência média de comunicação da rede de interconexão. S!o apresentados alguns resultados de simulações para um sistema em malha tridimensional com controle de fluxo tipo wormhole e variação no número de canais virtuais, utilizando um algoritmo de roteamento adaptativo com variação na política de seleção de saída. Estes resultados s!o comparados aos obtidos utilizando conhecido algoritmo estático ordenado por dimensões.
Sociedade Brasileira de Computação, Oct 3, 2011
Multimedia Tools and Applications
In order to create immersive experiences in virtual worlds, we need to explore different human se... more In order to create immersive experiences in virtual worlds, we need to explore different human senses (sight, hearing, smell, taste, and touch). Many different devices have been developed by both industry and academia towards this aim. In this paper, we focus our attention on the researched area of thermal and wind devices to deliver the sensations of heat and cold against people’s skin and their application to human-computer interaction (HCI). First, we present a review of devices and their features that were identified as relevant. Then, we highlight the users’ experience with thermal and wind devices, highlighting limitations either found or inferred by the authors and studies selected for this survey. Accordingly, from the current literature, we can infer that, in wind and temperature-based haptic systems (i) users experience wind effects produced by fans that move air molecules at room temperature, and (ii) there is no integration of thermal components to devices intended for t...
Proceedings of the 2nd Workshop on Multisensory Experiences (SensoryX 2022)
Multimedia applications are usually limited to stimulating only two human senses: vision and hear... more Multimedia applications are usually limited to stimulating only two human senses: vision and hearing. Recent studies seek to expand the definition of multimedia applications to include stimuli for other human senses. In this way, sensory effects that should be triggered in synchrony with the audiovisual content being presented are included in the applications. By including sensory effects in multimedia, we aim to improve the Quality of Experience (QoE) with these mulsemedia environments. Usually, two approaches are being used for performing QoE evaluations these environments. The first, more common, is performed by subjective evaluation approaches, i.e. through questionnaires, interrogations, oral responses, etc. The second, rarer but growing, uses objective approaches by collecting physiological data from the user when dealing with the system being evaluated. Such data is gathered in real time or not, however, it is considered objective because it is "involuntary", that i...
International Journal of Human-Computer Studies, 2021
Full bibliographic details must be given when referring to, or quoting from full items including ... more Full bibliographic details must be given when referring to, or quoting from full items including the author's name, the title of the work, publication details where relevant (place, publisher, date), pagination, and for theses or dissertations the awarding institution, the degree type awarded, and the date of the award.
2016 IEEE 30th International Conference on Advanced Information Networking and Applications (AINA), 2016
Content Centric Networking (CCN) represents an important change in the current operation of the I... more Content Centric Networking (CCN) represents an important change in the current operation of the Internet, prioritizing content over the communication between end nodes. Routers play an essential role in CCN, since they receive the requests for a given content and provide content caching for the most popular ones. They have their own forwarding strategies and caching policies for the most popular contents. Despite the number of works on this field, experimental evaluation of different forwarding algorithms and caching policies yet demands a huge effort in routers programming. In this paper we propose SDCCN, a SDN approach to CCN that provides programmable forwarding strategy and caching policies. SDCCN allows fast prototyping and experimentation in CCN. Proofs of concept were performed to demonstrate the programmability of the cache replacement algorithms and the Strategy Layer. Experimental results, obtained through implementation in the Mininet environment, are presented and evaluated.
ICST Transactions on Ubiquitous Environments, 2015
The development of methodologies and techniques to evaluate smartphones usability is an emerging ... more The development of methodologies and techniques to evaluate smartphones usability is an emerging topic in the scientific community and triggers discussions about which methodology is most appropriate. The lack of consensus is due to the inherent difficulty on capturing context data in the scenarios where the experiments take place and on relating them to the results found. This work aims at correlate potential usability problems in mobile applications with contextual factors that may occur during users' interactions on different devices, such as environment luminosity, device screen resolution, and the user's activity while interacting with the application. The following methodology was applied to carry out a field experiment: (1) identification of contextual factors that may influence users' interaction; (2) use of UXEProject Infrastructure to support the automatic capture of applications' context data, by monitoring and storing quantitative, subjective and contextual data from applications' use; (3) implementation of experiments with real users, which have different profiles, using three different mobile applications over an one year period. In this paper, we present and discuss the results obtained during this study.
Formal Description Techniques and Protocol Specification, Testing and Verification, 1998
Hypermedia authoring tools usually suffer from a lack of validation capabilities that would make ... more Hypermedia authoring tools usually suffer from a lack of validation capabilities that would make them capable of checking a document against temporal inconsistencies. The document design method proposed in the paper is meant to overcome this problem. The starting point is a document description provided in a high-level modeling technique featuring hypermedia basic concepts such as nodes (including composite nodes), anchors and links. The high-level document is then automatically translated into a RT-WTOS formal specification on which classical reachability analysis techniques are applied, making it possible to check the temporal consistency of the document structure. A simple example is used along the text to illustrate the proposed approach.
International Journal of Emerging Technologies in Learning (iJET)
This work is an approach that brings together Learning Analytics and Ontologies for a data classi... more This work is an approach that brings together Learning Analytics and Ontologies for a data classification that promotes improvements and behavioral changes for students and teachers on e-Learning platforms. Combining training courses, dashboards, user's evaluations, and based on Design Science Research (DSR) methodology, artifacts were created. One of the most important artifacts of our work is the Sapes tool that aims to improve students’ perceptions of their learning path and to promote a better teacher overview to follow their students' progress. The results showed high approval by the participating students and teachers, who perceived the Sapes tool as a good facilitator of the teaching-learning process, with possibilities for self-monitoring, dynamization of the learning sequence and better interactivity with colleagues, highlighted as absent in standard e-Learning courses. In addition, the application changed the behavior of users towards the content provided by the te...
Proceedings of the 23rd Brazillian Symposium on Multimedia and the Web
In this paper we concentrate on the study of the collaborative practices of enthusiasts that crea... more In this paper we concentrate on the study of the collaborative practices of enthusiasts that create and share subtitles for thirdparty videos. Based on preliminary results from interviews with some volunteers, we formalize the subtitles creation and sharing process using a business process management model and compare it with other collaborative and crowdsourcing models. We expect that our initial observations can bring a new understanding of the process and, thus, help in the design of next generation video enriching tools.
Proceedings of the 22nd Brazilian Symposium on Multimedia and the Web - Webmedia '16, 2016
Synchronization is about providing coherent orchestration of events or resources involved in a mu... more Synchronization is about providing coherent orchestration of events or resources involved in a multimedia application. In a synchronized application, the user has the notion that his device's content is directly connected with others. In this paper we discuss the existing synchronization techniques, their advantages and disadvantages, and the current implementations and usage. We also present our open source solution for local synchronization of Web applications, the Audio Markings API, detailing its usage, components and functionalities. The focus of this paper is on smart devices such as smartphones, tablets and laptops since they often have built-in microphones and speakers - resources that we intend to explore. In addition to that, those devices are perfectly capable of running full-featured web browsers, something that we also need to take advantage of. Our goal is to give developers an alternative for synchronization of Web applications, using the Web browser as a platform and the sound as a bridge.
2022 International Wireless Communications and Mobile Computing (IWCMC)
2020 IEEE International Conference on E-health Networking, Application & Services (HEALTHCOM), 2021
A major challenge for remote patient monitoring (RPM) systems is processing data collected from a... more A major challenge for remote patient monitoring (RPM) systems is processing data collected from a large number of healthcare devices and developing suitable algorithms and approaches to react accordingly to a wide spectrum of situations of interest, which must be properly detected. Flow-based programming, whose operation is based on state changes, is a promising approach to overcome this challenge, facilitating the personalization of data processing according to patients' health conditions. However, this approach is not suited to the detection of complex contextual situations, thereby hindering its adoption in RPM systems for data processing. In this regard, we propose an approach that combines situation awareness and flow-based programming to widen the capability of RPM systems to handle many-sided scenarios, which requires the monitoring of complex patient healthcare conditions. An evaluation of the proposed approach was conducted to demonstrate the flexibility of the solution for processing heterogeneous health information.
Proceedings of the 34th ACM/SIGAPP Symposium on Applied Computing, 2019
Agricultural greenhouses have improved productivity in the cultivation of specific crops. Efforts... more Agricultural greenhouses have improved productivity in the cultivation of specific crops. Efforts towards the automation of these environments have been carried out with the application of different technologies. However, the absence of a solution that comprises a complete chain of the automation process has been noted. Internet of Things (IoT) is a technology that can offer solutions for the modernization of agricultural environments, making it possible to automate processes, to predict situations, and to improve production activities. Moreover, IoT solutions and businesses process should be integrated into a common framework to provide a more efficient production process control, since business rules are often dynamic and might vary according to agriculture practices. In this fashion, we propose an architecture for sensing and actuating in controlled agricultural environments using business rules modeling as the central artifact for the automation of production chains. To validate the proposed architecture, we present a case study in which we describe the implementation and tools to support vegetable production. The study showed that the architecture is feasible to monitor crops, to collaborate to maximize yield and to control the use of inputs and agrochemicals. Furthermore, it caters for culture monitoring in real time, offering information to producers to aid decision making.
IEEE Transactions on Multimedia, 2020
Using olfactory media to enhance traditional multimedia content opens up novel opportunities for ... more Using olfactory media to enhance traditional multimedia content opens up novel opportunities for user interactions. Whilst the influence of olfaction on user experience in mulsemedia (multiple sensorial media) environments has been previously studied, the impact of the fundamental dimensions of scent intensity and valence (odor hedonic dimension or pleasantness) have been largely unexplored. This is precisely what we target in this paper, which reports the results of an empirical investigation examining how scent intensity and valence impact mulsemedia Quality of Experience (QoE). Accordingly, 54 participants were exposed to different odor valences and scent intensity levels when viewing three short multimedia clips. In particular, we examine both subjective (self-reported) as well as objective QoE metrics, as evidenced by user heart rates and eye gaze patterns. Results show that whilst eye gaze patterns are largely unaffected by the experimental conditions, valence does have a statistically significant impact upon user heart rates, as does intensity for two of the three clips employed in our study. In terms of subjective QoE, results indicate that hedonic valence impacts on the sense of reality and enjoyment; however varying odor intensity levels do not seem to differentially impact on user experience, bringing into question the need for strong scent intensities.
Crowdsourcing is a method that employs people to process input data to solve a computationally co... more Crowdsourcing is a method that employs people to process input data to solve a computationally complex problem, such as generating a large dataset of annotated images, audio transcriptions or video scene descriptions. In this approach, people select tasks and produce individual results according to a list of steps that leads to an efficient solution. Then, every single result must be collected, interpreted, and integrated by a platform or system supporting the crowdsourcing process. Considering that the first studies regarding this field of study were done by means of experimenting and observing platforms and systems that popularized this method. Given that, pertinent questions are: (i) besides platforms and systems, what are the essential elements that compose a crowdsourcing project?; (ii) how the humans are guided through the steps for solving the proposed problem?; (iii) how to ensure the quality of the results produced in all stages of a project?; and (iv) are there guidelines ...
Journal of Information Science, 2022
Crowdsourcing arose as a problem-solving strategy that uses a large number of workers to achieve ... more Crowdsourcing arose as a problem-solving strategy that uses a large number of workers to achieve tasks and solve specific problems. Although there are many studies that explore crowdsourcing platforms and systems, little attention has been paid to define what a crowd-powered project is. To address this issue, this article introduces a general-purpose conceptual model that represents the essential elements involved in this kind of project and how they relate to each other. We consider that the workflow in crowdsourcing projects is context-oriented and should represent the planning and coordination by the crowdsourcer in the project, instead of only facilitating decomposing a complex task into subtask sets. Since structural models are limited to cannot properly represent the execution flow, we also introduce the use of behavioural conceptual models, specifically Unified Modeling Language (UML) activity diagrams, to represent the user, tasks, assets, control activities and products inv...
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Papers by Celso Alberto Saibel Santos