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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Developing implant technologies and evaluating brain-machine interfaces using information theory

Panko, Mikhail 12 March 2016 (has links)
Brain-machine interfaces (BMIs) hold promise for restoring motor functions in severely paralyzed individuals. Invasive BMIs are capable of recording signals from individual neurons and typically provide the highest signal-to-noise ratio. Despite many efforts in the scientific community, BMI technology is still not reliable enough for widespread clinical application. The most prominent challenges include biocompatibility, stability, longevity, and lack of good models for informed signal processing and BMI comparison. To address the problem of low signal quality of chronic probes, in the first part of the thesis one such design, the Neurotrophic Electrode, was modified by increasing its channel capacity to form a Neurotrophic Array (NA). Specifically, single wires were replaced with stereotrodes and the total number of recording wires was increased. This new array design was tested in a rhesus macaque performing a delayed saccade task. The NA recorded little single unit spiking activity, and its local field potentials (LFPs) correlated with presented visual stimuli and saccade locations better than did extracted spikes. The second part of the thesis compares the NA to the Utah Array (UA), the only other micro-array approved for chronic implantation in a human brain. The UA recorded significantly more spiking units, which had larger amplitudes than NA spikes. This was likely due to differences in the array geometry and construction. LFPs on the NA electrodes were more correlated with each other than those on the UA. These correlations negatively impacted the NA's information capacity when considering more than one recording site. The final part of this dissertation applies information theory to develop objective measures of BMI performance. Currently, decoder information transfer rate (ITR) is the most popular BMI information performance metric. However, it is limited by the selected decoding algorithm and does not represent the full task information embedded in the recorded neural signal. A review of existing methods to estimate ITR is presented, and these methods are interpreted within a BMI context. A novel Gaussian mixture Monte Carlo method is developed to produce good ITR estimates with a low number of trials and high number of dimensions, as is typical for BMI applications.
132

Cortical motor prosthetics: the development and use for paralysis

Ziehm, Elaina MaryElizabeth 20 February 2018 (has links)
The emerging research field of Brain Computer Interfaces (BCIs) has created an invasive type of BCI, the Cortical Motor Prosthetic (CMP) or invasive BCI (iBCI). The goal is to restore lost motor function via prosthetic control signals to individuals who have long-term paralysis. The development of the CMP consists of two major entities: the implantable, chronic microelectrode array (MEA) and the data acquisition hardware (DAQ) specifically the decoder. The iBCI's function is to record primary motor cortex (M1) neural signals via chronic MEA and translate into a motor command via decoder extraction algorithms that can control a prosthetic to perform the intended movement. The ultimate goal is to use the iBCI as a clinical tool for individuals with long-term paralysis to regain lost motor functioning. Thus, the iBCI is a beacon of hope that could enable individuals to independently perform daily activities and interact once again with their environment. This review seeks to accomplish two major goals. First, elaborate upon the development of the iBCI and focus on the advancements and efforts to create a viable system. Second, illustrate the exciting improvements in the iBCI's use for reaching and grasping actions and in human clinical trials. The ultimate goal is to use the iBCI as a clinical tool for individuals with long-term paralysis to regain movement control. Despite the promise in the iBCI, many challenges, which are described in this review, persist and must be overcome before the iBCI can be a viable tool for individuals with long-term. iBCI future endeavors aim to overcome the challenges and develop an efficient system enhancing the lives of many living with paralysis. Standard terms: Intracortical Brain Computer Interface (iBCI), Intracortical Brain Machine Interface (iBMI), Cortical Motor Prosthetic (CMP), Neuromotor Prostheses (NMP), Intracortical Neural Prosthetics, Invasive Neural Prosthetic all terms used interchangeably
133

The cost of search and evaluation in problem-solving social networks : an experimental study

Farenzena, Daniel Scain January 2016 (has links)
Online networks of individuals have been used to solve a number of problems in a scale that would not be possible if not within a connected, virtual and social environment such as the internet. However, the quality of solutions provided by individuals of an online network can vary significantly thus making work quality unreliable. This dissertation investigates factors that can influence the quality of the work output of individuals in online social networks. Specifically, we show that when solving tasks with small duration (under 5 minutes), also known as microtasks, individuals decision making will be strongly biased by costs of searching (and evaluating) options rather than financial or non-financial incentives. Indeed, we are able to show that we can influence individuals decisions, when solving problems, by rearranging elements visually to modify an the search sequence of an individual, be it by designing the virtual work environment or manipulating which options are first shown in non-controlled environments such as the Amazon Mechanical Turk labor market. We performed several experiments in online networks where individuals are invited to work on tasks with varying degrees of difficulty within three settings: mathematical games with objective truth (Sudoku and SAT instances), surveys with subjective evaluation (public policy polling) and labor markets (Amazon Mechanical Turk). We show that the time spent solving problems and the user interface are more relevant to the quality of work output than previous research have assumed and that individuals do not change this behavior while solving the sets of problems. Finally, to complement our study of online problem-solving, we present additional experiments in an online labor market (Amazon Mechanical Turk) that agrees with our networked experiments, shedding new light on how and why people solve problems.
134

Entre Mnemo e Locus: arquitetura de espaços virtuais, construção de espaços mentais / Between Mnemo and Locus: Architecture of Virtual Space, Construction of Mental Space

Anja Pratschke 25 April 2002 (has links)
Propõe-se um método de construção arquitetural de espaços virtuais, baseado na sobreposição de diversos modos de pensar o espaço e no uso de estruturas da mnemotécnica. Para essa tarefa, faz-se, inicialmente, uma análise crítica do estado da arte em dois campos disciplinares recorrentemente envolvidos na construção de tais ambientes: Interface Usuário-Computador e Realidade Virtual. Em seguida apresenta-se a maneira de se sobrepor diversos modos de pensar o espaço em Arquitetura, a qual constitui o terceiro campo disciplinar desse estudo, explicitado através da introdução e da análise de diferentes exemplos de concepções arquitetônicas pertencentes ao âmbito virtual. Definido como pertencente à mente, o espaço virtual é concebido através de métodos arquitetônicos, acrescidos do uso da Mnemônica, que é a arte e a técnica de se desenvolver e fortalecer a memória. O processo de memorização torna-se central no processo de construção do contexto virtual. Introduzido através de exemplos na história e de recentes aplicações artísticas em realidade virtual, a tese propõe a inclusão da mnemotécnica para a estruturação espacial arquitetônica no virtual / A method is proposed for the architectural construction of virtual spaces based on the overlaying of diverse ways of thinking about space and by using structures of mnemotechniques. In order to achieve this task, a critical review is first carried out of two disciplines which are regularly involved in the construction of this kind of spatiality: Human-Computer Interface, and Virtual Reality. Architecture, as a third and central discipline, presents its method of overlaying diverse ways of thinking space, made explicit through the introduction and analysis of different examples of architectural construction in the virtual realm. Defined as belonging to the mind, the virtual space is conceived through architectural methods by adding the use of Mnemonics, which is the art and technique of developing and making stronger the memory. The memorization process itself becomes central in the process of constructing the virtual context. Introducing examples in history and recent art applications in virtual reality, the thesis proposes the introduction of mnemotechniques for the architectural spatial structuring of the virtual
135

Human Scapes: o design de plataformas participativas móveis para a cidade digitalmente conectada / Human Scapes: the design of mobile participatory platforms for the city digitally connected

Kelly Kiyumi Shigeno 19 May 2016 (has links)
A difusão tecnológica e cultural do uso de dispositivos móveis está presente em todas as camadas da sociedade. Utilizados como mediadores em diferentes redes de comunicação, eles também carregam o significado de um espaço pessoal para o usuário. Sua utilização constante os transforma em potenciais sensores pessoais, gerando dados continuamente. Neste cenário, instituições e organizações governamentais utilizam-se de ferramentas digitais de georreferenciamento nos grandes centros urbanos do Brasil e do mundo para disponibilizar serviços ou coletar dados. Com o intuito de adaptar o modelo de navegação orientada utilizado na análise de portais governamentais para a análise de aplicativos móveis, foi realizada uma navegação orientada nos aplicativos selecionados, entre eles o 1746 RIO desenvolvido pelo Governo do Rio de Janeiro e o Colab desenvolvido por uma organização da sociedade civil. A navegação foi realizada com o auxilio de um roteiro de perguntas divididas em cinco principais categorias de análise: Acesso e Privacidade, Visualização e Edição de Informações, Feedback, Comunicação Social e Elementos de Gamificação. Para compreender o processo de experiência da cidadania foram realizadas entrevistas com uma ONG de São Paulo e observações em oficinas realizadas com cidadãos na cidade de Sorocaba. Pretende-se contribuir para o conhecimento na área de design e cidadania, apontando elementos e características para o desenvolvimento de aplicações móveis participativas voltadas para grandes cidades. / The technological and cultural dissemination of mobile devices usage is present in all segments of society. Used as an interface between different communication networks, mobile devices can also transform any space into one\'s own personal space. Its constant use convert them into potential personal sensors, generating data continuously. To adapt to this new paradigm governments are starting to implement georeference tools in order to provide services or collect data from major urban areas. Aiming to adapt the oriented navigation method to be performed in mobile devices, we designed a questionnaire roadmap acknowledging the main features of mobile devices. The analyzed applications include: Colab and 1746 Rio. The first is an initiative developed for citizens in a bottom-up approach intending to establish communication with city managers. The second was created by the City Hall of Rio de Janeiro and follows a topdown approach, being designed as a call center for the city residents. The questions were grouped in 5 main themes: Access rights and Privacy, View and Change Reports Data, Social Communication, Feedback, and Gamification Elements. In order to better understand how the citizenship is currently addressed, we conducted interviews with a São Paulo\'s NGO member. Also performed a non-participant observation over a workshop held at Sorocaba. This research aims to contribute to the discussion over the design and citizenship areas, suggesting elements and features for the development of participative mobile applications focused on data gathering in major cities.
136

A Study of the Relationship Between the Use of Color for Text in Computer Screen Design and the Age of the Computer User

D'Angelo, John J. 12 1900 (has links)
This study addresses an individual's performance, relating it to eyesight changes due to the aging of the individual and to color computer screens used for computer-based-instruction not designed specifically for older students. This study determines how existing research in gerontology, human-computer interface, and color use in visual graphics can be applied to the design of computer screen displays containing color text and backgrounds and how various color combinations will affect performance by adult learners forty years of age and older. The results of this research provide software developers and instructional designers guidelines to use when designing computer screen displays for use in instructional computing settings involving older adults.
137

Brain Computer Interface (BCI) : - Översiktsartikel utifrån ett neuropsykologiskt perspektiv med tillämpningar och enkätundersökning / Brain Computer Interface (BCI) – a review articlewithin a neuropsychological perspective with applications and survey

Lind, Carl Jonas January 2020 (has links)
Syftet med uppsatsen är att ge en uppdaterad översikt av området BCI (Brain Computer Interface) och undersöka vad som hänt sedan begreppet introducerades i forskningssammanhang; vilka praktiska resultat forskningen lett till och vilka tillämpningar som tillkommit. Metoden som företrädesvis används är litteraturstudie som tecknar bakgrund och enkät. Därefter följer en diskussion där utmaningar för framtiden, potential och tillämpningar i BCI-tekniken behandlas utifrån ett neuropsykologiskt perspektiv. Kommer BCI-tekniken att implementeras på samma sätt som radio, TV och telekommunikationer i samhället och vilka etiska och tekniska problem finns idag. För att skildra allmänhetens uppfattning om BCI genomfördes en webbaserad enkätundersökning (survey) i form av pilotstudie (n=32) som syftar till att ge en indikation på attityder och hur allmänhetens opinion med avseende på tillämpningar i samtiden och jämförelser med avseende på teknisk bakgrund.
138

Une approche MDA pour l'intégration de la personnalisation du contenu dans la conception et la génération des applications interactives / An MDA approach for content personalization integration in the design and the generation of interactive applications

Bacha, Firas 16 May 2013 (has links)
Les travaux de recherche présentés dans ce mémoire se situent dans les thématiques de la génération des applications interactives et de la personnalisation du contenu. Cette thèse propose une approche de type MDA (Model Driven Architecture), indépendante du domaine d’application, permettant la conception et la génération semi-automatique des applications interactives à contenus personnalisés, compte tenu des informations sur le contexte d’utilisation et l’ontologie de domaine. Cette approche met en œuvre deux méthodes de personnalisation du contenu, à savoir le remplissage automatique des formulaires et l’enrichissement des requêtes. Pour atteindre cet objectif, nous avons développé la solution technique permettant la conception, la transformation des modèles ainsi que la génération de l’IHM (Interface Homme-Machine) finale. / The research work presented in this thesis belongs to the fields of interactive applications generation and content personalization. This thesis proposes an MDA (Model Driven Architecture) approach, independent of the domain application, allowing the design and the semi-automatic generation of personalized content interactive applications. This generation relies on context information and the domain ontology. This approach implements two content personalization methods ; namely the forms auto-filling and the automatic queries enrichment. To achieve this goal, we developed the technical solution allowing the design, the models transformations as well as the generation of the final HCI (Human-Computer Interface).
139

Combining Fitts’s Law with Angular Size

Gillenwater, Jacob, Fields, Stephen, Cornett, Cheryl, Wallace, Chrisopher 12 April 2019 (has links)
Human-computer interaction is a growing field of computer science that combines psychological, biomechanical, and engineering design principles to help cater to a user's experience. Dr. Fitts created a mathematical model in 1954 which could accurately describe the difficulty of using a particular one-dimensional user interface, which was subsequently expanded to encompass two-dimensional user interfaces. Contemporary technological advances in virtual and augmented reality are currently leading towards widespread commercial use. This experiment attempts to adapt Fitts’s model once again to accommodate the three-dimensional user interfaces required of virtual and augmented reality. My hypothesis is that an object's angular size can be supplemented into Fitts’s model instead of its physical size. Participants were asked to wear a virtual reality headset and look at pairs of targets. Each pair has a different physical size, but the same angular size. The participants head movements are tracked using the virtual reality headset to determine how long it took each participant to find the center of a target. Linear regression is used to track the distance from the participants center of view to the center of a target over time. The slope of this regression lines is representative of the difficulty slope described by Fitts’s original model. The difficulty slopes are then plotted and compared to one another. Once using the targets’ physical size as the independent variable, and once using the target’s angular size as the independent variable. The coefficient of determination of the two data sets is then compared. If there exists a stronger relationship between the difficulty slope and the angular size of the target compared to the difficulty slope and the physical size of the target, then my hypothesis is true. Research is ongoing, but early preliminary test suggests that my hypothesis is correct. This means that an object's angular size can be supplemented into existing models instead of its physical size. This conclusion allows software developers and user interface designers to create more easily used and more optimized user interfaces.
140

Using machine learning to analyse EEG brain signals for inner speech detection

Jonsson, Lisa January 2022 (has links)
Research on brain-computer interfaces (BCIs) has been around for decades and recently the inner speech paradigm was picked up in the area. The realization of a functioning BCI could improve the life quality of many people, especially persons affected by Locked-In-Syndrome or similar illnesses. Although implementing a working BCI is too large of a commitment for a master's thesis, this thesis will focus on investigating machine learning methods to decode inner speech using data collected from the non-invasive and portable method electroencephalography (EEG). Among the methods investigated are three CNN architectures and transfer learning. The results show that the EEGNet architecture consistently reaches high classification accuracies, with the best model achieving an accuracy of 29.05%.

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