This paper describes the design and simulation of a network interface unit (NIU) for a picture archiving and communication system (PACS) network called PACnet. PACnet is a dual fiber optic ring network under development at the Computer Engineering Research Laboratory of the University of Arizona. This network integrates voice, data, and image communications in a hospital environment and supports a throughput rate between 200-500 megabits per second. At each node in the network, an NIU implements the Data Link Layer and Physical Layer protocols of PACnet. The initial network interface unit design for PACnet was a functional description of NIU protocols and major components. In order to construct a demonstration prototype of PACnet,the NIU description must be refined and an architecture must be specified. The NIU design is specified and simulated using the hardware description language VHDL. Simulation results provide information on NIU timing characteristics and logic families required to implement the NIU.

The United States Army Corp of Engineers relies on accurate and detailed surface models for various construction projects and preventative measures. To aid in these efforts, it is necessary to work for advancements in surface model creation. Current methods for model creation include Delaunay triangulation, raster grid interpolation, and Hydraulic Spline grid generation. While these methods produce adequate surface models, attempts for improved methods can still be made. A method for raster based spline creation is presented as a variation of the Hydraulic Spline algorithm. By implementing Hydraulic Splines in raster data instead of vector data, the model creation process is streamlined. This method is shown to be more efficient and less computationally expensive than previous methods of surface model creation due to the inherent advantages of raster data over vector data.

Une interface cerveau-machine (ICM) est un système qui permet d'établir une communication directe entre le cerveau et un dispositif externe, en contournant les voies de sortie normales du système nerveux périphérique. Différents types d'ICMs existent dans la littérature. Parmi eux, les ICMs basées sur l'imagerie motrice sont les plus prometteuses. Elles sont basées sur l'autorégulation des rythmes sensorimoteurs par l'imagination de mouvement des membres différents (par exemple, imagination du mouvement de la main gauche et la main droite). Les ICMs basées sur l'imagerie motrice sont les meilleurs candidats pour les applications dédiées à des patients sévèrement paralysés mais elles sont difficiles à mettre en place parce que l'autorégulation des rythmes du cerveau n'est pas une tâche simple.Dans les premiers stades de la recherche en ICMs basées sur l'imagerie motrice, l'utilisateur devait effectuer des semaines, voire des mois, d'entrainement afin de générer des motifs d'activité cérébrale stables qui peuvent être décodés de manière fiable par le système. Le développement des techniques d'apprentissage automatique supervisé spécifiques à chaque utilisateur a permis de réduire considérablement la durée d'entrainement en ICMs. Cependant, ces techniques sont toujours confrontées aux problèmes de longue durée de calibrage et non-stationnarité des signaux cérébraux qui limitent l'utilisation de cette technologie dans la vie quotidienne. Bien que beaucoup de techniques d'apprentissage automatique avancées ont été essayées, ça reste toujours pas un problème non résolu.Dans cette thèse, j'étudie de manière approfondie les techniques d'apprentissage automatique supervisé qui ont été tentées afin de surmonter les problèmes de longue durée de calibrage et la non-stationnarité des signaux cérébraux en ICMs basées sur l'imagerie motrice. Ces techniques peuvent être classées en deux catégories: les techniques qui sont invariantes à la non-stationnarité et les techniques qui s'adaptent au changement. Dans la première catégorie, les techniques d'apprentissage par transfert entre différentes sessions et/ou différents individus ont attiré beaucoup d'attention au cours des dernières années. Dans la deuxième catégorie, différentes techniques d'adaptation en ligne des modèles d'apprentissage ont été tentées. Parmi elles, les techniques basées sur les potentiels d'erreurs sont les plus prometteuses. Les deux principales contributions de cette thèse sont basés sur des combinaisons linéaires des classificateurs. Ainsi, ces méthodes sont accordées un intérêt particulier tout au long de ce manuscrit. Dans la première contribution, je étudie l'utilisation de combinaisons linéaires des classificateurs dans les ICMs basées sur l'apprentissage par transfert et je propose une méthode de classification inter-sujets basée sur les combinaisons linéaires de classifieurs afin de réduire le temps de calibrage en ICMs. Je teste l'efficacité de la méthode de combinaison de classifieurs utilisée et j'étudie les cas ou l'apprentissage par transfert a un effet négatif sur les performances des ICMs. Dans la deuxième contribution, je propose une méthode de classification inter-sujets qui permet de combiner l'apprentissage par transfert l'adaptation en ligne. Dans cette méthode, l'apprentissage par transfert est effectué en combinant linéairement des classifieurs appris à partir de signaux EEG de différents sujets. L'adaptation en ligne est effectué en mettant à jours les poids de ces classifieurs d'une manière semi-supervisée. / A brain-computer interface (BCI) is a system that allows establishing direct communication between the brain and an external device, bypassing normal output pathways of peripheral neuromuscular system. Different types of BCIs exist in literature. Among them, BCIs based on motor imagery (MI) are the most promising ones. They rely on self-regulation of sensorimotor rhythms by imagination of movement of different limbs (e.g., left hand and right hand). MI-based BCIs are best candidates for applications dedicated to severely paralyzed patients but they are hard to set-up because self-regulation of brain rhythms is not a straightforward task.In early stages of BCI research, weeks and even months of user training was required in order to generate stable brain activity patterns that can be reliably decoded by the system. The development of user-specific supervised machine learning techniques allowed reducing considerably training periods in BCIs. However, these techniques are still faced with the problems of long calibration time and brain signals non-stationarity that limit the use of this technology in out-of-the-lab applications. Although many out-of-the-box machine learning techniques have been attempted, it is still not a solved problem.In this thesis, I thoroughly investigate supervised machine learning techniques that have been attempted in order to overcome the problems of long calibration time and brain signals non-stationarity in MI-based BCIs. These techniques can be mainly classified into two categories: techniques that are invariant to non-stationarity and techniques that adapt to the change. In the first category, techniques based on knowledge transfer between different sessions and/or subjects have attracted much attention during the last years. In the second category, different online adaptation techniques of classification models were attempted. Among them, techniques based on error-related potentials are the most promising ones. The aim of this thesis is to highlight some important points that have not been taken into consideration in previous work on supervised machine learning in BCIs and that have to be considered in future BCI systems in order to bring this technology out of the lab. The two main contributions of this thesis are based on linear combinations of classifiers. Thus, these methods are given a particular interest throughout this manuscript. In the first contribution, I study the use of linear combinations of classifiers in knowledge transfer-based BCIs and I propose a novel ensemble-based knowledge transfer framework for reducing calibration time in BCIs. I investigate the effectiveness of the classifiers combination scheme used in this framework when performing inter-subjects classification in MI-based BCIs. Then, I investigate to which extent knowledge transfer is useful in BCI applications by studying situations in which knowledge transfer has a negative impact on classification performance of target learning task. In the second contribution, I propose an online inter-subjects classification framework that allows taking advantage from both knowledge transfer and online adaptation techniques. In this framework, called “adaptive accuracy-weighted ensemble” (AAWE), inter-subjects classification is performed using a weighted average ensemble in which base classifiers are learned using EEG signals recorded from different subjects and weighted according to their accuracies in classifying brain signals of the new BCI user. Online adaptation is performed by updating base classifiers' weights in a semi-supervised way based on ensemble predictions reinforced by interaction error-related potentials.

Typescript (photocopy). / Digitized by Kansas Correctional Industries / Department: Electrical and Computer Engineering.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Bibliography: leaves 122-124. / by Frederich Nelson Tou. / M.S.

Locked-in syndrome (LIS) is a condition characterized by total or near-total paralysis with preserved cognitive and somatosensory function. For the locked-in, brain-machine interfaces (BMI) provide a level of restored communication and interaction with the world, though this technology has not reached its fullest potential. Several streams of research explore improving BMI performance but very little attention has been given to the paradigms implemented and the resulting constraints imposed on the users. Learning new mental tasks, constant use of external stimuli, and high attentional and cognitive processing loads are common demands imposed by BMI. These paradigm constraints negatively affect BMI performance by locked-in patients. In an effort to develop simpler and more reliable BMI for those suffering from LIS, this dissertation explores using error-related potentials, the neural correlates of error awareness, as an access pathway for adaptive decoding and direct volitional control. In the first part of this thesis we characterize error-related local field potentials (eLFP) and implement a real-time decoder error detection (DED) system using eLFP while non-human primates controlled a saccade BMI. Our results show specific traits in the eLFP that bridge current knowledge of non-BMI evoked error-related potentials with error-potentials evoked during BMI control. Moreover, we successfully perform real-time DED via, to our knowledge, the first real-time LFP-based DED system integrated into an invasive BMI, demonstrating that error-based adaptive decoding can become a standard feature in BMI design. In the second part of this thesis, we focus on employing electroencephalography error-related potentials (ErrP) for direct volitional control. These signals were employed as an indicator of the user’s intentions under a closed-loop binary-choice robot reaching task. Although this approach is technically challenging, our results demonstrate that ErrP can be used for direct control via binary selection and, given the appropriate levels of task engagement and agency, single-trial closed-loop ErrP decoding is possible. Taken together, this work contributes to a deeper understanding of error-related potentials evoked during BMI control and opens new avenues of research for employing ErrP as a direct control signal for BMI. For the locked-in community, these advancements could foster the development of real-time intuitive brain-machine control.

Made available in DSpace on 2014-07-29T16:27:56Z (GMT). No. of bitstreams: 1 pretextuais.pdf: 218961 bytes, checksum: 8704851b129017a5d0787dc7933461a6 (MD5) Previous issue date: 2009-06-29 / This work analyses, under a phenomenological point of view, our perception of the cyberspace, since we are beings in the world. The study begins considering the hypothesis that the cyberspace is in the interface; thus it is in the natural world. Besides, this study questions how the approximation between the physical space and the cyberspace happens, and it defends the existence of a continuity between them. In order to do so, we discussed many aspects related to not only the cyberspace, but also the natural world, the own body, the perception, the computer interfaces, the real and the virtual, along the text, trying to understand how the perception works to later understand the perception itself. The research led us to some conclusions which were used in the development of a practical proposition which represents the imagetic production for this master course. The project, through a modified chess game, questions the notion of continuity between both the physical space and the cyberspace. To achieve this objective, we described the chess game elements, and we elect, among technical possibilities, a way for the poetic materialization of this project which is the modification of the game rules and of the perception that we have of it. In the end, this research made clear the phenomenical orientation of the project, highlighting the understanding of perception as a bodily act, part of a single process in which the body experience is as important as the conscience, in contrast to the positive conception. / A dissertação analisa, sob um ponto de vista fenomenológico, a percepção que temos, enquanto ser no mundo, do ciberespaço. O estudo se inicia considerando como hipótese que o ciberespaço se inscreve na interface e, portanto no mundo natural. Questiona como se dá a aproximação entre o espaço físico e o ciberespaço, e defende a existência de uma continuidade entre eles. Para tal, no decorrer do texto, abordamos vários aspectos não só do ciberespaço, mas também do mundo natural, do corpo próprio, da percepção, das interfaces computacionais, do real e do virtual, buscando entender a forma como a percepção se dá, para poder compreendê-la. As conclusões obtidas a partir da pesquisa realizada são utilizadas para desenvolver uma proposta prática, que se configura na produção imagética de mestrado. Um projeto que, através de um jogo de xadrez modificado, questiona a noção de continuidade entre os espaços físico e o ciberespaço. Para isso, a dissertação descreve elementos do jogo de xadrez e elege, na técnica, uma forma de concretização poética do projeto, que se realiza na modificação de regras do jogo e da percepção que temos do mesmo. Ao final o texto dissertativo evidencia a orientação fenomênica do projeto, ao destacar a compreensão da percepção como um ato corpóreo, parte de um único processo em que a experiência do corpo está em igual importância com a consciência, opondo-se a uma visão positivista.

Fish such as the Leopard Shark (Triakis semifasciata) can be tagged on their fin, released back into the wild, and their location tracked though technologies such as autonomous robots. Timestamped location data about their target is stored. We present a way to procedurally generate an animated simulation of T. semifasciata using only these timestamped location points. This simulation utilizes several components. Input timestamps dictate a monotonic time-space curve mapping the simulation clock to the space curve. The space curve connects all the location points as a spline without any sharp folds that are too implausible for shark traversal. We create a model leopard shark that has convincing kinematics that respond to the space curve. This is achieved through acquiring a skinned model and applying T. semifasciata motion kinematics that respond to velocity and turn commands. These kinematics affect the spine and all fins that control locomotion and direction. Kinematic- based procedural keyframes added onto a queue interpolate while the shark model traverses the path. This simulation tool generates animation sequences that can be viewed in real-time. A user study of 27 individuals was deployed to measure the perceived realism of the sequences as judged by the user by contrasting 5 different film sequences. Results of the study show that on average, viewers perceive our simulation as more realistic than not.

The research described in this thesis examines indigenous language usage in a digital library environment that has been accessed via the Internet. By examining discretionary use of the Māori Niupepa and Hawaiian Nūpepa digital libraries this research investigates how indigenous languages were used in these electronic environments in 2005. The results provide encouragement and optimism to people who are striving to retain, revitalise and develop the use of indigenous languages in information technologies. The Transaction Log Analysis (TLA) methods used in this research serve as an example of how web logs can be used to provide significant information about language usage in a bilingual online information system. Combining the TLA with user feedback has provided insights into how and why clients use indigenous languages in their information retrieval activities. These insights in turn, show good practice that is relevant not only to those working with indigenous languages, indigenous peoples or multilingual environments, but to all information technology designers who strive for universal usability. This thesis begins by describing the importance of using indigenous languages in electronic environments and suggests that digital libraries can provide an environment to support and encourage the use of such languages. TLA is explained in the context of this study and is then used to analyse aspects of te reo Māori usage in the Niupepa digital library environment in 2005. TLA also indicates that te reo Māori was used by international clients and this usage differed to te reo Māori usage by national (Aotearoa) clients. Findings further reveal that the default language setting of the Niupepa digital library had a considerable impact on te reo Māori usage. When the default language was set to te reo Māori not only were there more requests in te reo Māori but there was also a higher usage of te reo Māori in the information retrieval activities. TLA of the Hawaiian Nūpepa digital library indicated that the Hawaiian language was also used in a digital library. These results confirm that indigenous languages were used in digital library environments. Feedback from clients suggests reasons why indigenous languages were used in this environment. These reasons include the indigenous language content of the digital library, the indigenous language default language setting of the digital library and a stated desire by the clients to use the indigenous language. The key findings raise some interface design issues and support the claim that digital libraries can provide an environment to support the use of indigenous languages.

This field study looks at the apparent changes in consciousness undergone by those who work at sophisticated computer interfaces and explores various models for what could be happening. The work draws strongly on Jean Gebser's work on the evolution of consciousness and is also inspired by Martin Heidegger's The Question Concerning Technology. Appropriate methodologies are developed based on Husserl's phenomenology and its resurgence in the work of Francisco Varela. I develop some of my own models for what could be happening and a set of questions for in-depth interviews. The results of the interviews and of a workshop are analysed to see if my suppositions are supported by others' observations. A discussion on the possible impact on the counselling profession is also included.