Une question centrale des recherches sur la lecture concerne la nature séquentielle ou parallèle de l’identification des mots pendant la lecture de phrases. L’hypothèse dominante postule que l’attention spatiale est allouée à un seul mot à la fois, et qu’avec cette contrainte, l’identification des mots doit forcément s’opérer de manière séquentielle. Cependant, un certain nombre de résultats suggèrent, au contraire, que l’attention spatiale peut être allouée à plusieurs mots à la fois, de manière distribuée. Cette attention disbribuée pourrait permettre l’identification en parallèle de plusieurs mots de manière simultanée, et les travaux présentés dans cette thèse cherchent à déterminer la viabilité de cette hypothèse. Notamment, nos travaux visent à préciser le niveau de traitement (visuel, orthographique, lexical, sémantique ou syntaxique) permis par cette attention distribuée. / This thesis addresses one of the most hotly debated issues in reading research: Are words processed serially or in parallel during reading? One could argue that this is primarily a question of visuo-spatial attention: is attention distributed across multiple words during reading? The research presented here suggests that attention can indeed be allocated to multiple words at once. It is further established that attention is a key factor driving (sub-lexical) orthographic processing. The next question, then, is whether multiple lexical representations can be activated in parallel. This thesis comprises a wealth of evidence for parallel lexical activation: firstly we have found that readers activate embedded words (e.g., ‘use’ in ‘houses’) alongside the word that is to be recognized, indicating that parallel lexical processing would occur even if readers could effectively focus their attention on single words. Moreover, we have found that semantic and syntactic categorization decisions about foveal target words are influenced by the semantic and syntactic aspects of surrounding words, even when all these words are presented for a duration shorter than the average time needed to recognize a single word. Hence, given that readers’ attention is spread across multiple words and that multiple lexical representations can be activated in parallel, it seems reasonable to claim that the reading system is in principle a parallel processing system.

The ability of traditional active sonar processing methods to detect targets is often limited by clutter and reverberation from ocean environments. Similarly, multipath arrivals from radiating sources such as ships and submarines are received at sensors in passive sonar systems. Reverberation and multipath signals introduce constructive and destructive interference patterns in received spectrograms in both active and passive sonar applications that vary with target range and frequency. The characterization and use of interference phenomena can provide insights into environmental parameters and target movement in conjunction with standard processing methods including spectrograms and array beamforming. This thesis focuses on utilizing the time-frequency interference structure of moving targets captured on sonar arrays to enhance the resolution and abilities of conventional sonar methods to detect and localize targets. Physics-based methods for interference-based beamforming and target depth separation are presented with application of these methods shown using broadband simulated array data.

The main outcomes of this research are the design of a foreground detection algorithm, which is more accurate and less time consuming than existing algorithms. By the term accuracy we mean an exact mask (which satisfies the respective ground truth value) of the foreground object(s). Motion detection being the prior component of foreground detection process can be achieved via pixel based and block based methods, both of which have their own merits and disadvantages. Pixel based methods are efficient in terms of accuracy but a time consuming process, so cannot be recommended for real time applications. On the other hand block based motion estimation has relatively less accuracy but consumes less time and is thus ideal for real-time applications. In the first proposed algorithm, block based motion estimation technique is opted for timely execution. To overcome the issue of accuracy another morphological based technique was adopted called opening-and-closing by reconstruction, which is a pixel based operation so produces higher accuracy and requires lesser time in execution. Morphological operation opening-and-closing by reconstruction finds the maxima and minima inside the foreground object(s). Thus this novel simultaneous process compensates for the lower accuracy of block based motion estimation. To verify the efficiency of this algorithm a complex video consisting of multiple colours, and fast and slow motions at various places was selected. Based on 11 different performance measures the proposed algorithm achieved an average accuracy of more than 24.73% than four of the well-established algorithms. Background subtraction, being the most cited algorithm for foreground detection, encounters the major problem of proper threshold value at run time. For effective value of the threshold at run time in background subtraction algorithm, the primary component of the foreground detection process, motion is used, in this next proposed algorithm. For the said purpose the smooth histogram peaks and valley of the motion were analyzed, which reflects the high and slow motion areas of the moving object(s) in the given frame and generates the threshold value at run time by exploiting the values of peaks and valley. This proposed algorithm was tested using four recommended video sequences including indoor and outdoor shoots, and were compared with five high ranked algorithms. Based on the values of standard performance measures, the proposed algorithm achieved an average of more than 12.30% higher accuracy results.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The international space community, including National Aeronautics and Space Administration (NASA), European Space Agency (ESA), Japanese National Space Agency (NASDA) and others, are committed to using the Consultative Committee for Space Data Systems (CCSDS) recommendations for low earth orbiting satellites. With the advent of the CCSDS standards and the availability of direct broadcast data from a number of current and future spacecraft, a large number of users could have access to earth science data. However, to allow for the largest possible user base, the cost of processing this data must be as low as possible. By utilizing Very Large Scale Integration (VLSI) Application-Specific Integrated Circuits (ASIC), pipelined data processing, and advanced software development technology and tools, highly integrated CCSDS data processing can be attained in a single desktop system. This paper describes a prototype desktop system based on the Peripheral Component Interconnect (PCI) bus that performs CCSDS standard frame synchronization, bit transition density decoding, Cyclical Redundancy Check (CRC) error checking, Reed-Solomon decoding, data unit sorting, packet extraction, annotation and other CCSDS service processing. Also discussed is software technology used to increase the flexibility and usability of the desktop system. The reproduction cost for the system described is less than 1/8th the current cost of commercially available CCSDS data processing systems.

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

published_or_final_version / Management Studies / Master / Master of Business Administration

published_or_final_version / Computer Science / Master / Master of Philosophy

published_or_final_version / abstract / Computer Science / Master / Master of Philosophy

published_or_final_version / abstract / Computer Science / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy