Determining the Best Sensing Coverage for 2-Dimensional Acoustic Target Tracking

Distributed acoustic target tracking is an important application area of wireless sensor networks. In this paper we use algebraic geometry to formally model 2-dimensional acoustic target tracking and then prove its best degree of required sensing coverage. We present the necessary conditions for three sensing coverage to accurately compute the spatio-temporal information of a target object. Simulations show that 3-coverage accurately locates a target object only in 53% of cases. Using 4-coverage, we present two different methods that yield correct answers in almost all cases and have time and memory usage complexity of Θ(1). Analytic 4-coverage tracking is our first proposed method that solves a simultaneous equation system using the sensing information of four sensor nodes. Redundant answer fusion is our second proposed method that solves at least two sets of simultaneous equations of target tracking using the sensing information of two different sets of three sensor nodes, and fusing the results using a new customized formal majority voter. We prove that 4-coverage guarantees accurate 2-dimensional acoustic target tracking under ideal conditions

A Survey on Multimedia-Based Cross-Layer Optimization in Visual Sensor Networks

Visual sensor networks (VSNs) comprised of battery-operated electronic devices endowed with low-resolution cameras have expanded the applicability of a series of monitoring applications. Those types of sensors are interconnected by ad hoc error-prone wireless links, imposing stringent restrictions on available bandwidth, end-to-end delay and packet error rates. In such context, multimedia coding is required for data compression and error-resilience, also ensuring energy preservation over the path(s) toward the sink and improving the end-to-end perceptual quality of the received media. Cross-layer optimization may enhance the expected efficiency of VSNs applications, disrupting the conventional information flow of the protocol layers. When the inner characteristics of the multimedia coding techniques are exploited by cross-layer protocols and architectures, higher efficiency may be obtained in visual sensor networks. This paper surveys recent research on multimedia-based cross-layer optimization, presenting the proposed strategies and mechanisms for transmission rate adjustment, congestion control, multipath selection, energy preservation and error recovery. We note that many multimedia-based cross-layer optimization solutions have been proposed in recent years, each one bringing a wealth of contributions to visual sensor networks

Personality and cognitive factors in the assessment of multimodal stimuli in immersive virtual environments

Literature in the study of human response to immersive virtual reality systems often deals with the phenomenon of presence. It can be shown that audio and imagery with spatial information can interact to affect presence in users of immersive virtual reality. It has also been shown that there is variation between individuals in the experience of presence in VR. The relationship between these effects has hitherto not been fully explored. This thesis aims to identify and evaluate the relation- ships between spatial audio rendering and spatial relationships between audio and visual objects and cognitive and personality differences which account for variation in the experience of presence in VR with spatial audio. This thesis compares mea- sures of audiovisual quality of experience with an existing model of presence in a factor-analytical paradigm. Scores on these dimensions were compared between en- vironments which are similar or dissimilar to pre-exposure conditions and compared between when participants believed they were listening to real-world or headphone rendered audio events. Differences between audiovisual treatments, including au- dio rendering methods and audiovisual spatial relationships, were compared with differences attributed to cognitive and personality factors identified as significant predictors using hierarchical modelling. It was found that audiovisual quality of experience relates to subscales of presence by being independent of reported visual realism and involvement, but combines linearly with these factors to contribute to ’spatial presence’, a dimension of overall presence which is identified as the largest component in the construct. It was also found that, although manipulation of the spatial information content of audiovisual stimuli was a predictor of audiovisual quality of experience, this effect is overshadowed by inter-participant variation. In- teractive effects between extraversion, empathy, ease of resolving visual detail, and systematisation and are better predictors of quality of experience and spatial pres- ence than the changes to spatial information content investigated in this work. An- choring biases are also identified which suggest that novel environments are rated higher on audiovisual quality than those geometrically similar to the pre-exposure environment. These findings constitute support for a novel framework for assessing propensity for presence in terms of an information-processing model

World Modeling for Intelligent Autonomous Systems

The functioning of intelligent autonomous systems requires constant situation awareness and cognition analysis. Thus, it needs a memory structure that contains a description of the surrounding environment (world model) and serves as a central information hub. This book presents a row of theoretical and experimental results in the field of world modeling. This includes areas of dynamic and prior knowledge modeling, information fusion, management and qualitative/quantitative information analysis

The creation of a binaural spatialization tool

The main focus of the research presented within this thesis is, as the title suggests, binaural spatialization. Binaural technology and, especially, the binaural recording technique are not particu-larly recent. Nevertheless, the interest in this technology has lately become substantial due to the increase in the calculation power of personal computers, which started to allow the complete and accurate real-time simulation of three-dimensional sound-fields over headphones. The goals of this body of research have been determined in order to provide elements of novelty and of contribution to the state of the art in the field of binaural spatialization. A brief summary of these is found in the following list: • The development and implementation of a binaural spatialization technique with Distance Simulation, based on the individual simulation of the distance cues and Binaural Reverb, in turn based on the weighted mix between the signals convolved with the different HRIR and BRIR sets; • The development and implementation of a characterization process for modifying a BRIR set in order to simulate different environments with different characteristics in terms of frequency response and reverb time; • The creation of a real-time and offline binaural spatialization application, imple-menting the techniques cited in the previous points, and including a set of multichannel(and Ambisonics)-to-binaural conversion tools. • The performance of a perceptual evaluation stage to verify the effectiveness, realism, and quality of the techniques developed, and • The application and use of the developed tools within both scientific and artistic “case studies”. In the following chapters, sections, and subsections, the research performed between January 2006 and March 2010 will be described, outlining the different stages before, during, and after the development of the software platform, analysing the results of the perceptual evaluations and drawing conclusions that could, in the future, be considered the starting point for new and innovative research projects

Virtual reality training for micro-robotic cell injection

This research was carried out to fill the gap within existing knowledge on the approaches to supplement the training for micro-robotic cell injection procedure by utilising virtual reality and haptic technologies

Perception multimodale de la distance dans un environnement virtuel

76 pagesLa position des objets dans un espace est défini par trois coordonnées : l'azimut, l'élévation et la distance. Bien que certaines études aient étudié la perception d'objets sonores et visuels en élévation et en azimut, peu d'études se sont focalisées sur la perception en distance. Cependant, il a été montré que les humains sous-estiment la distance d'objets sonores et visuels distants et sur-estiment la distance d'objets sonores et visuels proches. L'humain perçoit la distance d'un objet et la profondeur d'une scène par le biais de plusieurs indices. Ceux-ci sont combinés afin d'estimer avec précision la distance et la profondeur. Les applications de réalité virtuelle permettent de manipuler des objets dans un environnement généralement multimodal. Pour cela, il est nécessaire de reproduire fidèlement la position des objets dans cet environnement virtuel. La perception de la profondeur est affectée par différents facteurs inhérents aux environnements virtuels comme le champ de vision restreint ou la visualisation d'images de synthèse non réalistes. Une des techniques les plus employées en réalité virtuelle afin de reproduire la profondeur d'un environnement est la stéréoscopie. Cette technique reproduit certains indices de vision binoculaire. Cependant, cette technique ne permet pas de reproduire fidèlement l'ensemble des indices visuels car elle découple la convergence et l'accommodation. Cette étude a pour but de comparer, dans des tâches de perception de la distance égocentrique, la restitution sonore spatialisée et le rendu visuel stéréoscopique

Quality assessment of e-commerce websites using Bayesian belief networks

This thesis raises the issue of quality in E-commerce websites and addresses methodologies and approaches to standardize their assessment. The thesis blends the knowledge of academic research with the opinions and insights from experts and practitioners in the field to provide a comprehensive view of the issues and their remedies. The most experienced and successful E-commerce companies are beginning to realize that key determinants of success or failure are not merely a web presence or a low price but delivering a high quality website. Recent research shows that price and promotion are no longer the main draws for customers to make a decision on a purchase. More sophisticated online customers would rather pay a higher price to a provider with high quality service. Given that the establishment of an E-commerce website is mainly a software development effort; there are several standards that apply in governing the quality of such development. There seems to be an almost overwhelming abundance of quality standards that lead to a high level of cynicism and skepticism surrounding them and the eventual lack of use. Furthermore, no standard can directly predict the quality a website under development is going to achieve. Past approaches concerning the quality of E-commerce websites emphasize usability standards using techniques like feature inspection and collecting data about end-users' opinion by questionnaires. These methods provide important feedback and their results can be utilized as a useful background for future work, however, they do not contribute directly to a dynamic model that enables forecasting. The study of quality in the domain of the Internet in general, and E-commerce in particular, poses new challenges as technology evolves, including methods and metrics for estimating, managing quality during the product life cycle and quality-of-use measurement. The solution proposed by this research is to use a Bayesian Belief Network model. This model provides a consistent and practical approach to assessing the quality of the website. The assessment can be carried out before the completion of the website development, thus, providing insight on the trend and direction for correction and improvements. It can also be carried out on completed and operational work, providing analysis of areas for improvement. The model should be relatively quick and practical in providing an overall comprehensive assessment with root-cause analysis that would lead to corrective measures to improve the quality of the E-commerce website. In this research idioms were applied in realizing a complete Bayesian Belief Network model. The conclusions are measured against comparative assessment to validate the practical benefits of the work accomplished. The WebQual method was utilized to validate the "belief" established by the model.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Quality assessment of e-commerce websites using Bayesian belief networks

This thesis raises the issue of quality in E-commerce websites and addresses methodologies and approaches to standardize their assessment. The thesis blends the knowledge of academic research with the opinions and insights from experts and practitioners in the field to provide a comprehensive view of the issues and their remedies. The most experienced and successful E-commerce companies are beginning to realize that key determinants of success or failure are not merely a web presence or a low price but delivering a high quality website. Recent research shows that price and promotion are no longer the main draws for customers to make a decision on a purchase. More sophisticated online customers would rather pay a higher price to a provider with high quality service. Given that the establishment of an E-commerce website is mainly a software development effort; there are several standards that apply in governing the quality of such development. There seems to be an almost overwhelming abundance of quality standards that lead to a high level of cynicism and skepticism surrounding them and the eventual lack of use. Furthermore, no standard can directly predict the quality a website under development is going to achieve. Past approaches concerning the quality of E-commerce websites emphasize usability standards using techniques like feature inspection and collecting data about end-users' opinion by questionnaires. These methods provide important feedback and their results can be utilized as a useful background for future work, however, they do not contribute directly to a dynamic model that enables forecasting. The study of quality in the domain of the Internet in general, and E-commerce in particular, poses new challenges as technology evolves, including methods and metrics for estimating, managing quality during the product life cycle and quality-of-use measurement. The solution proposed by this research is to use a Bayesian Belief Network model. This model provides a consistent and practical approach to assessing the quality of the website. The assessment can be carried out before the completion of the website development, thus, providing insight on the trend and direction for correction and improvements. It can also be carried out on completed and operational work, providing analysis of areas for improvement. The model should be relatively quick and practical in providing an overall comprehensive assessment with root-cause analysis that would lead to corrective measures to improve the quality of the E-commerce website. In this research idioms were applied in realizing a complete Bayesian Belief Network model. The conclusions are measured against comparative assessment to validate the practical benefits of the work accomplished. The WebQual method was utilized to validate the "belief" established by the model.EThOS - Electronic Theses Online ServiceGBUnited Kingdo