One of the fundamental problems related to the development of direct sequence code division multiple access (DS CDMA) wireless data networks is design of spreading sequences possessing semi-optimal characteristics. In this thesis, we introduce three new methods to design spreading sequences, which can be optimised to achieve the desired characteristics.We show that the level of MAI for the DS CDMA systems utilising the example sets of sequences designed by the use of these techniques can be relatively low, compare to the case when the well known Gold-like sequences [29] are used. In addition, we show that by using one of the methods introduced in the thesis, we can construct sets of orthogonal sequences possessing acceptable correlation properties, even for an asynchronous operation, while another of the introduced methods can be used if design of sequences of an arbitrary length is required.Our new methods to design complex polyphase sequences are orientated towards the short length sequences, as a target application for them are high data rate wireless networks. Those methods are based on using discretised chirp pulses, pulses consisting of discretised multiple chirps, or linear combinations of them. In order to achieve orthogonality among the designed polyphase sequences, we combined the sequences based on superimposed chirps and double chirps with the sequences derived from the orthogonal Walsh functions.Finally, we utilise the three most promising sequence sets designed by the use of die introduced methods to simulate the multiuser DS CDMA systems. We compare performance of those simulated systems with the performance of the simulated system utilising 15-chip Gold- like sequences. The comparison results indicate that by using our design methods, we can produce useful sequence sets for applications where short spreading sequences are required. The presented ++ / results also demonstrate that the performance of systems utilising those sequences can be significantly better in terms of the number of simultaneously active users or bit error rate (BER) that the performance of the system employing Gold or Gold-like sequences of the similar length.

Récemment, nombres d'alternatives à la traditionnelle modulation d'intensité ont été proposées dans le contexte des télécommunications optiques. Les systèmes dits cohérents, utilisant la phase de l'onde optique, présentent de nombreux avantages : meilleure sensibilité, resistance à divers effets non-linéaires. Ils montrent néanmoins un comportement différent vis à vis du bruit accumulé lors de la propagation. L'effet Kerr dans la fibre induit un bruit de phase non-linéaire qui limite les performances de ces systèmes.<br />Dans une première partie, l'estimation rapide, analytique ou semi-analytique, de ces fluctuations est proposée dans deux contextes différents. Les résultats alors obtenus par application de la méthode des moments et de la théorie des perturbations sont validés par des simulations numériques de la propagation. Nous menons également une étude expérimentale de l'influence de la carte de dispersion sur le bruit de phase.<br />Dans une deuxième partie, nous proposons et étudions un format de modulation basé sur la modulation de phase différentielle continue, dans le but d'améliorer l'efficacité spectrale. Ce format est obtenu en modulant la phase optique par un signal à trois niveaux de type duobinaire. Ses performances sont comparées à celles des formats standards au débit de 10 Gbit/s lors d'une expérience utilisant une boucle à recirculation.

La prochaine génération d'infrastructures de communication par fibre optique comprendra des systèmes de transmission longue distance avec du multiplexage en longueur d'onde (WDM) à 40 et 100 Gb / s, et sera très probablement basée sur la détection cohérente. Le travail de thèse décrit dans ce manuscrit étudie ces systèmes. Nous démontrons d'abord leur tolérance inégalée à des effets physiques linéaires de propagation, grâce au traitement numérique du signal réalisé dans le récepteur. Néanmoins, les systèmes optiques peuvent être limités aussi par des effets non-linéaires de propagation. Cette thèse explore le comportement non-linéaire des signaux détectés avec un récepteur cohérent, spécialement quand ils sont multiplexés en polarisation. Nous avons particulièrement étudié l'évolution de l'impact des non-linéarités quand le débit augmente de 40 à 100 Gb/s, en démontrant que l'augmentation du débit accroît la tolérance à certaines non-linéarités. Cette thèse examine également l'interaction entre la dispersion modale de polarisation (PMD) et les non-linéarités. Contrairement aux systèmes existants, nous avons prouvé que, lorsque la PDM est distribuée, elle s'avère souvent être bénéfique en réduisant les pénalités causées par les non-linéarités. Au contraire, quand la PMD est localisée, elle peut augmenter la dégradation causée par lesdites non-linéarités. Finalement, comme une preuve de l'intérêt porté par les opérateurs aux technologies à 100 Gb/s, ce manuscrit présente les résultats d'un essai de terrain que nous avons mené récemment sur le réseau de Telefónica en Espagne montrant le potentiel des technologies cohérente pour moderniser les réseaux existants.

This study was designed to identify students’ perceptions of learning activities, assessment formats, and content on their understanding of the nature of science (NOS) by comparing and examining constructs created by Canadian and Korean students. Participants were 217 Canadian and 319 Korean Grade 8 students that filled out questionnaires; additionally, 9 students volunteered for semi-structured interviews. Descriptive statistics, multivariate analysis of variance and partial least squares were used to examine the quantitative data. A conceptually clustered matrix was used for the qualitative analyses. Results indicated that students from both countries perceived 1) their learning activities were teacher-directed, 2) class presentations and discussions occurred least frequently, 3) paper-and-pencil tests determined science scores, 4) science tests relied heavily on knowledge of science while knowledge about science was least likely to be assessed, and 5) generally students held relativistic views on science. The effect for country on NOS concepts was statistically significant across all of their perceptions except for the concepts of culturally embedded science and the perceptions of short-answer test formats. Specifically, Canadian students perceived that they had relatively more student-directed activities while Korean students perceived that they had more teacher-directed science lab activities. Further, Canadian students were inclined to hold more relativistic views across the NOS concepts. It was also noted that Korean students provided more political examples while Canadian students provided stem cell research or environmental issues. An examination of associations revealed that students’ learning activities, assessment formats, and content are good predictors of NOS understanding since these constructs explain variances from 19.7% for Empirical NOS to 63% for Scientific Methods. Results from students’ open-ended responses to the NOS concepts and the semi-structured interviews were consistent with the quantitative analyses. Most interviewees agreed that what, and how, they learned science-- and how their learning was assessed--affected their views of science since school science education was the important factor in developing their scientific knowledge. These results imply that diverse learning activities and assessments could prove to be a better approach to enhancing students’ understanding of NOS than teacher-directed learning activities and test formats requiring a single correct answer.

<p>The overall aim of the study is to get a better understanding for the relation between different forms of representation in ICT-interfaces and cognitive variation in individuals. Cognitive style is, according to Riding & Al-Hajji (2000) ”an individual’s preferred and habitual approach to both organizing and representing information”. Research of the relation between cognitive style and learning performance has shown, according to Riding & Al-Hajji (2000), that pupils learn best when the structure, the content and the mode of presentation of the material suits their style.</p><p>On the basis of an explorative pre-analysis of a multimedia program for learning mathematics, named Matador, a general hypothesis was formulated. The general hypothesis that was examined is: The Matador multimedia program can be improved as concerns the presentational formats both for pupils who are helped by and attracted by visual information and – in particular – for pupils who are helped by and attracted by verbal information. A minor user’s test with 10-15 year old pupils was carried out in order to complement the pre-analysis by testing some specific details of the program with users. The results of the study indicate that there are certain aspects that could be improved, especially for those who are helped by and attracted by verbal information.</p>

This study had three main purposes. First, the relationship between Processing Speed (Gs) and poor word recognition skills was examined. Second, various formats of processing speed tests that measure different types of processing speed (i.e. naming facility, perceptual speed, semantic speed, attention and concentration) were administered to determine what aspects of Gs were more strongly correlated with word reading performance. Pearson correlations and coefficients of determination were used to evaluate the strength of the relationships and the shared variance. Third, the study sample was evaluated to determine what percentage of the poor readers participating in the study had slow processing speed.Forty-four students in grades 1-3, ages six- to ten-years old were administered the Woodcock-Johnson III Achievement reading tests of Letter-Word Identification, Reading Fluency, and Word Attack. The subjects were additionally administered the Woodcock-Johnson III Cognitive Abilities tests of Verbal Comprehension, Visual-Auditory Learning, Sound Blending, Visual Matching, Numbers Reversed, Decision Speed, Rapid Picture Naming, Pair Cancellation, and Cross Out.The results of the study indicated processing speed, as measured by the Gs Cluster score, was strongly correlated with word reading, r = .749, r2=.56. The Gs tests of Visual Matching, (r = .663, r2 = .44) and Decision Speed (r = .811, r2 = .66) were most strongly correlated with poor word reading skill. The Basic Reading Skills Cluster and the Test of Letter-Word Identification were both moderately correlated at various strengths with different formats of Gs tests. Tests of Visual Matching, Rapid Picture Naming, Pair Cancellation and Cross Out all had a moderate, significant correlation.Lastly, 47% of the poor readers (SS<85 on any of the measures of>reading) also had low Gs scores (SS<85).The results from the study demonstrate the need for further exploration of the impact of poor Gs on the development of reading skills, as well as determination of the most effective interventions for poor readers with slow processing speed.

Il est devenu commun de dire que notre société se transforme inexorablement en une société dite de « l'information ». Cette transformation se caractérise entre autres par une utilisation accrue des technologies de l'information afin de communiquer, d'échanger ou de transiger. Les supports traditionnels de communication (tel que le papier) cèdent progressivement leur place à de nouveaux supports technologiques favorisant l'efficacité et la rapidité des échanges, et par la même occasion le développement du commerce électronique. Qu'on le souhaite ou non, un constat s'impose: la montée en puissance des réseaux virtuels a eu raison du monopole du papier. Sur le plan juridique, cette nouvelle réalité bouleverse aussi considérablement les règles de droit civil largement pensées et ancrées dans un contexte papier. L'avènement de la numérisation et du phénomène de la dématérialisation des supports ont effectivement soulevé plusieurs questions d'ordre juridique tout à fait nouvelles que nous pourrions résumer de la manière suivante: Quels sont les rapports entre l'écrit et son support autre que le papier? Quelles sont les caractéristiques de l'écrit faisant appel aux technologies de l'information? Ce type d'écrit peut-il être admis en tant que moyen de preuve? Si oui, quelle sera sa force probante? Ce type d'écrit doit-il être conservé? Le présent mémoire vise précisément à identifier certains éléments de réponses à ces diverses questions en étudiant spécifiquement les cadres juridiques français et québécois. Ce mémoire traite d'une part des enjeux liés à l'évolution et au rôle de l'écrit face à l'avènement des technologies de l'information et d'autre part du cadre juridique de la preuve et de la conservation de l'écrit dans la société de l'information. / It is becoming commonplace to say that we have entered a so-called "information society". In the process, we have witnessed a transformation characterized by an increased use of information and communication technologies that has revolutionized the way we communicate, learn and conduct business. The traditional communication formats (i.e., paper) gradually yield their place to new technological formats which affect the effectiveness and the speed of transactions, there by enabling the rise of ecommerce. The advent of virtual networks calls into question the monopoly of paper. From a legal perspective, the new paradigm has a huge impact on civil law rules, which were largely anchored in a paper context. The advent of the digitization and the phenomenon of the dematerialization of formats raised several new legal issues that we could summarize in the following manner: What is the relationship between writing and its various formats (e.g., other than paper)? What characterizes writing in an electronic environment? Can this type of writing act as evidence? If so, what will be its conclusive force? How can the integrity of documents be ensured? This thesis examines these various questions within the context of two different legislations: France and Québec. Two issues are addressed: 1) the evolution ofwriting in an electronic, networked environment; 2) the legal framework around evidence and archiving ofwriting in the information society. / "Mémoire présenté à la faculté des études supérieures en vue de l'obtention du grade de maîtrise en droit (L.L.M.)"

Electronic document handling was first used in the automotive industry in the early 1970’s, the way of communicating electronic at the time was concerned with the communication way of EDI (Hsieh, 2004). In the beginning of 2000 a new way of communicating electronic documents was introduced with the emergence of VAN-operators (Hsieh, 2004). This technology of communicating electronic invoices has shown to be less complex for the businesses than the previous EDI connections. The VAN-operators enable companies regardless of size, ERP, also known as Enterprise Resource Planning, system, formats or transaction volume to send and receive electronic invoices. The subject of electronic invoice handling have become increasingly debated, mainly because of the legislations taking place all over Europe, and as well as the environmental impact by business transactions being sent by paper. The objective of this thesis is to examine the challenges, solutions and outcomes for companies switching to electronic invoice handling. The data collected for the thesis is divided into two parts. The first part consist of information retrieved by previous literature as well as internet sources. The second part concerns the case studies conducted for the thesis in respect to our research questions. For this reason Scandinavian companies have been interviewed, with different precondition as in size, industry, transaction volume and IT structure. The findings from the first and second part have been analyzed and conclusion have been made, we suggest using a VAN-operators, which have shown to be the most appropriate alternative for companies that are implementing electronic invoice handling. The result of this thesis can be used as a guideline for companies when considering a switch from manual to electronic invoice handling.

This thesis studies and mathematically models nonlinear interactions among channels of modern high bit rate (amplitude/) phase modulated optical systems. First, phase modulated analogue systems are studied and a differential receiving method is suggested with experimental validation. The main focus of the rest of the thesis is on digital advanced modulation format systems. Cross-talk due to fiber Kerr nonlinearity in two-format hybrid systems as well as 16-QAM systems is mathematically modelled and verified by simulation for different system parameters. A comparative study of differential receivers and coherent receivers is also given for hybrid systems. The model is based on mathematically proven assumptions and provides an intuitive analytical understanding of nonlinear cross-talk in such systems. / Graduate

This study was designed to identify students’ perceptions of learning activities, assessment formats, and content on their understanding of the nature of science (NOS) by comparing and examining constructs created by Canadian and Korean students. Participants were 217 Canadian and 319 Korean Grade 8 students that filled out questionnaires; additionally, 9 students volunteered for semi-structured interviews. Descriptive statistics, multivariate analysis of variance and partial least squares were used to examine the quantitative data. A conceptually clustered matrix was used for the qualitative analyses. Results indicated that students from both countries perceived 1) their learning activities were teacher-directed, 2) class presentations and discussions occurred least frequently, 3) paper-and-pencil tests determined science scores, 4) science tests relied heavily on knowledge of science while knowledge about science was least likely to be assessed, and 5) generally students held relativistic views on science. The effect for country on NOS concepts was statistically significant across all of their perceptions except for the concepts of culturally embedded science and the perceptions of short-answer test formats. Specifically, Canadian students perceived that they had relatively more student-directed activities while Korean students perceived that they had more teacher-directed science lab activities. Further, Canadian students were inclined to hold more relativistic views across the NOS concepts. It was also noted that Korean students provided more political examples while Canadian students provided stem cell research or environmental issues. An examination of associations revealed that students’ learning activities, assessment formats, and content are good predictors of NOS understanding since these constructs explain variances from 19.7% for Empirical NOS to 63% for Scientific Methods. Results from students’ open-ended responses to the NOS concepts and the semi-structured interviews were consistent with the quantitative analyses. Most interviewees agreed that what, and how, they learned science-- and how their learning was assessed--affected their views of science since school science education was the important factor in developing their scientific knowledge. These results imply that diverse learning activities and assessments could prove to be a better approach to enhancing students’ understanding of NOS than teacher-directed learning activities and test formats requiring a single correct answer.