The main focus of the thesis is to derive stability criteria for networked control system (NCS) models featuring imperfections such as time-varying and constant delays, quantization, packet dropouts, and non-uniform sampling intervals. The main method of proof is based on matrix algebra, as opposed to methods using Lyapunov functions or integral quadratic constraints (IQC). This work puts a particular focus on handling systems with a single integrator. This framework is elaborated in different specific directions as motivated by practical realizations of NCSs, as well as through numerical examples. A novel proof of the discrete time multivariate circle criterion and the Tsypkin criterion for systems including a single integrator is presented, as well as a stability criterion for linear systems with a single integrator subject to variable sampling periods and sector-bounded nonlinear feedback. Four stability criteria for different classes of systems subject to packet loss and time-varying delay are given. Stability criteria for a closed loop system switching between a set of linear time-invariant systems (LTIs) are proved. This result is applied to a single-link NCS with feedback subject to packet loss. Finally, necessary and sufficient conditions for delay-independent stability of an LTI system subject to nonlinear feedback are derived.

The issue of identity has generated a significant amount of research in recent years. In this literature review, the relationship between learner identity and accent is explored, specifically the learner’s cultural affiliation and identity and the link to his/her accent acquisition in a second or foreign language. Social networks, motivation, L1 use, socio-cultural knowledge, discrimination and power relations, and anxiety are all shown to affect parts of the learner’s cultural identity, which, in turn, may influence his/her accent in the L2. / text

This literature review sets out to revisit the studies exploring impact of rater characteristics on language oral assessments. Three categories of raters' backgrounds: occupation, accent familiarity, and native language are identified and will be addressed respectively in the following sections. The results showed that no consensus regarding raters' occupational background, linguistic background and native-speaker status on examiners' rating has been found so far. However, this review will highlight the current testing situations, bring up limitations from previous studies, provide implications for both teachers and raters, and hopefully shed light on future research. / text

This thesis considers possible criteria for the selection of example sentences for difficult or unknown words in reading texts for students of German as a Second Language (GSL). The examples are intended to be provided within the context of an Intelligent Computer-Aided Language Learning (ICALL) Vocabulary Learning System, where students can choose among several explanation options for difficult words. Some of these options (e.g. glosses) have received a good deal of attention in the ICALL/Second Language (L2) Acquisition literature; in contrast, literature on examples has been the near exclusive province of lexicographers. The selection of examples is explored from an educational, L2 teaching point of view: the thesis is intended as a first exploration of the question of what makes an example helpful to the L2 student from the perspective of L2 teachers. An important motivation for this work is that selecting examples from a dictionary or randomly from a corpus has several drawbacks: first, the number of available dictionary examples is limited; second, the examples fail to take into account the context in which the word was encountered; and third, the rationale and precise principles behind the selection of dictionary examples is usually less than clear. Central to this thesis is the hypothesis that a random selection of example sentences from a suitable corpus can be improved by a guided selection process that takes into account characteristics of helpful examples. This is investigated by an empirical study conducted with teachers of L2 German. The teacher data show that four dimensions are significant criteria amenable to analysis: (a) reduced syntactic complexity, (b) sentence similarity, provision of (c) significant co-occurrences and (d) semantically related words. Models based on these dimensions are developed using logistic regression analysis, and evaluated through two further empirical studies with teachers and students of L2 German. The results of the teacher evaluation are encouraging: for the teacher evaluation, they indicate that, for one of the models, the top-ranked selections perform on the same level as dictionary examples. In addition, the model provides a ranking of potential examples that roughly corresponds to that of experienced teachers of L2 German. The student evaluation confirms and notably improves on the teacher evaluation in that the best-performing model of the teacher evaluation significantly outperforms both random corpus selections and dictionary examples (when a penalty for missing entries is included).

Syftet med studien är att undersöka hur mycket talutrymme elever med annat modersmål än svenska får och tar i klassrummet, i jämförelse med elever med svenska som modersmål. Särskild vikt läggs vid utrymmet för utforskande tal och mediering. Studien utgår från det sociokulturella perspektivet enligt vilket allt lärande sker i en social kontext. Det empiriska underlaget bygger på strukturerade observationer i sammanlagt sex klasser i år 1-2, med kompletterande anteckningar. Observationerna genomfördes under 100 minuter per klass. Resultatet presenteras i kvantitativ form. Resultatet visade att L1-talarna var de som tog och fick mest talutrymme även om skillnaden var marginell. Däremot fick L2-talarna något fler direkta frågor än L1-talarna. Mediering användes i samtliga klasser, men inte i den grad som var befogat. Utforskande tal användes aldrig under de sammanlagt 600 minuter som observerades. Detta resultat visar att lektionsstrukturen behöver ses över så att den bättre uppmuntrar och kräver att eleverna ska prata. Att använda sig av fler direkta, öppna frågor kan även fördela talutrymmet bättre mellan eleverna. Man kan även använda sig av så kallade minilektioner där talet står i fokus. Genom att vara mer flexibel med möbleringen i klassrummet kan man skapa fler möjligheter till interaktion eleverna emellan.

Abstract The aim of the study is to investigate how class teachers and Swedish L2 teachers perceive their work with recently arrived immigrant pupils in grades F to 3. Six teachers were interviewed about how they teach so that these pupils will achieve the target skills in Swedish as a second language in grade 3, and about their view of the integration of newly arrived pupils in the ordinary class and the preparatory class. In the study the teachers say that they lack shared guidelines for receiving newly arrived pupils and that the charting of the pupils is inadequate. The teachers prefer direct placement in the ordinary class because the pupils learn from others and improve in their zone of proximal development. The informants feel that they have sufficient training to teach newly arrived pupils and that working with them contributes to their professional development. The results of the study indicate that development-based teaching can benefit newly arrived pupils. The teachers say that they teach many words and concepts and use concrete material.

In second language (L2) listening assessment, various factors have the potential to impact the validity of listening test items (Brindley & Slatyer, 2002; Buck & Tatsuoka, 1998; Freedle & Kostin, 1999; Nissan, DeVincenzi, & Tang, 1996; Read, 2002; Shohamy & Inbar, 1991). One relatively unexplored area to date is who controls the aural input. In traditional standardized listening tests, an administrator controlled recording is played once or twice. In real world or classroom listening, however, listeners can sometimes request repetition or clarification. Allowing listeners to control the aural input thus has the potential to add test authenticity but requires careful design of the input and expected response as well as an appropriate computer interface. However, if candidates feel less anxious, allowing control of listening input may enhance examinees' experience and still reflect their listening proficiency. Comparing traditional and self paced (i.e., examinees having the opportunity to start, stop, and move the audio position) delivery of multiple choice comprehension items, my research inquiry is whether self paced listening can be a sufficiently reliable and valid measure of examinees' listening ability. Data were gathered from 100 prospective and current university ESL students. They were administered computer based multiple choice listening tests: 10 identical once played items, followed by 33 items in three different conditions: 1) administrator paced input with no audio player visible, 2) self paced with a short time limit, and 3) self paced with a longer time limit. Many facet Rasch (1960/1980) modeling was used to compare the difficulty and discrimination of the items across conditions. Results indicated items on average were similar difficulty overall but discriminated best in self paced conditions. Furthermore, the vast majority of examinees reported they preferred self paced listening. The quantitative results were complemented by follow up stimulated recall interviews with eight participants who took 22 additional test items using screen capture software to explore whether and when they paused and/or repeated the input. Frequency of and reasons for self pacing did not follow any particular pattern by proficiency level. Examinees tended to play more than once but not two full times through, even without limited time. Implications for listening instruction and classroom assessment, as well as standardized testing, are discussed.

It is widely recognised that parents play an important role in children’s emotional and intellectual development, including their success at school. Recently, there has been a growing awareness of the potential of parents to support and enhance children’s English foreign language learning, especially since English learning resources are easily accessible through electronic media. In appreciation of this, there has been an increased interest in recent years in finding ways to harness parental potential through the creation of home-school partnerships in many parts of the world, including in the field of teaching English as an additional language. An important point of departure for developing effective home-school dialogues is an informed understanding of what parents are already doing to support their children’s learning, as an awareness of this can help schools and governments provide parents with targeted input to assist and improve their efforts. However, to date, this remains under researched. Of the limited research that has been undertaken, very little has examined parental efforts to support their children’s learning at home in non-western settings, and research into parental support for children’s foreign language learning is virtually non-existent. In order to address this research gap, the study reported in this thesis examines parental support for young children’s foreign language learning in Saudi Arabia with respect to English T.V. viewing. Drawing upon Vygotsky’s concepts of mediation and the ZPD, it aims to examine the extent and the ways in which parents currently mediate their children’s viewing of English T.V. programmes in Saudi Arabia, the factors which impact on their mediation practices, and how this is seen to contribute to their children’s experience of English language learning. The study is comprised two stages. The first stage entails the distribution of a questionnaire to 500 parents of children aged 6-8, who are currently learning English in a number of private schools in Jeddah, in Saudi Arabia in order to gain a global overview of parental perspectives on mediation. This is followed by stage 2, which aims to examine the features and quality of parent-child mediational dialogues. This is achieved by collecting recordings of the dialogues of two parent-child dyads watching DVDs of English T.V. programmes over a four-week period as well as interviewing parents and their children on the experience. The results of the study show that parents believe in the importance and value of supporting their children’s learning (both in general and with regard to their EFL learning). Moreover, they show that they are actively engaged in trying to do so. However, they also highlight a number of ways in which their mediational practices could be improved so that these are less directive and more responsive to their children’s learning needs and growing ability to self-regulate. More broadly, they highlight the need to engage with the complexity of parental mediation as an activity system in discussions of the quality of mediational practice. That is, to understand that parental efforts to mediate need to be considered alongside task, sociocultural setting and, most importantly, the child’s engagement with parental efforts. A number of implications are drawn from the results of the study. Chief among these is that research into parental mediation should look at the inter-relationship between the different elements of the parental mediational system identified and that this provides richer in-depth understandings of parental efforts to support their children than are currently available from those who seek to understand this merely as parental scaffolding. In addition, it is argued that the picture this in-depth analysis revealed provides valuable information which can be used to inform the need for home-school partnerships and the support parents need to make sure they engage in these effectively in settings such as Saudi Arabia where there is currently little appreciation of the importance of parental involvement and the concept of home school partnerships remains in its infancy. In line with the emphasis on the complex multidimensional understanding of mediation as activity as illustrated by the results of the study, it is argued that efforts to promote parental involvement should primarily focus on how parents can help promote quality learning experiences for their children.

Les verbes de position suédois encodent la localisation statique (stå « être debout », ligga « être couché », sitta « être assis ») et dynamique (ställa « mettre debout », lägga « coucher », sätta « asseoir ») d'un objet concret ou d'une personne. Selon nos données, élicitées à partir de stimuli présentés à 98 participants, la fréquence élevée de l'emploi de ces verbes en assure une acquisition précoce par les enfants apprenant le suédois en tant que langue maternelle et par les francophones adultes apprenant le suédois en tant que langue étrangère. Or, leur complexité sémantique rend difficile leur utilisation dans la mesure où les choix d'un verbe ne correspondent pas toujours à ceux de la langue cible. En effet, les difficultés perdurent même à un haut niveau de compétence (enfants de 10 ans, apprenants L2 avancé). Un ordre d'acquisition se discerne d'une part selon le type de verbe (les verbes statiques sont appris avant les dynamiques), d'autre part selon les paramètres sémantiques (l'HORIZONTALITÉ et la VERTICALITÉ sont appris avant la BASE et le CONTACT/INCLUSION), et enfin selon le sens prototypique (acquis avant les sens élargis). Plusieurs stratégies sont utilisées par les apprenants pour résoudre ces problèmes : l'usage d'un verbe statique pour encoder une situation dynamique ; l'usage généralisé de l'un des verbes (généralement celui encodant l'HORIZONTALITÉ) ; l'usage collocationnel d'un verbe avec une Figure ; l'usage d'une ellipse verbale ou d'un verbe positionnellement neutre (ex. la copule). L'acquisition par les apprenants L2 de l'organisation discursive de la langue cible semble se faire en dernier lieu, due à la différence typologique des deux langues. / The Swedish posture verbs encode static (stå « stand », ligga « lie », sitta « sit ») and dynamic (ställa « stand », lägga « lay », sätta « set ») location of a person or a concrete object. The elaborated stimuli elicited data from 98 participants. Our data shows that the usage frequency of these verbs guarantees an early acquisition by children learning Swedish as their first language and by adult French-speaking learners of Swedish as a second language. However, their semantic complexity constitutes an obstacle for arriving at idiomatic language use with regard to choosing the correct verb. These difficulties exist even at high levels of competence (children of 10 years and advanced L2 learners respectively). An acquisition order can be distinguished regarding the verb type (static verbs are acquired before the dynamic ones), the semantic parameters (HORIZONTALITY and VERTICALITY are acquired before BASE and CONTACT/CONTAINMENT) and the prototypical meaning (acquired before the extended meanings). Several strategies are used by the learners to solve these problems: the use of a static verb to encode a dynamic situation; the generalized use of one of the verbs (generally the one encoding HORIZONTALITY); a collocational use of a verb and a Figure; the use of a verbal ellipsis or a positionally neutral verb, like the copula. The Swedish discourse organization seems to be acquired late by the L2 learners, due to the typological differences between the two languages.

>Magister Scientiae - MSc / This study describes the synthesis and characterisation of Cu(II) and V(IV) complexes of tri- and quadridentate ligands L1 and L2 formed by condensation of ethylenediamine with acetylacetonate in 1:1 and 1:2 molar ratio, respectively. Encapsulation of these metal complexes in the nanocage of zoilite-Y generates new heterogeneous catalysts. These catalysts were synthesized employing the flexible ligand method encapsulation technique.The structures of these encapsulated complexes were established on the basis of various physico-chemical and spectroscopic studies. The results indicated that the complexes did not hinder or modify the framework or structure of the zeolite, confirming successful immobilization of Schiff-bases through the voids of zeolite Y.These encapsulated complexes were screened as heterogeneous catalysts for various oxidation reactions such as such as phenol, benzene, styrene and cyclohexene using a green oxidant (H2O2).For comparison, the corresponding neat complexes were screened as potential homogeneous catalysts for these oxidation reactions. The results proved that the corresponding homogeneous systems described here represent an efficient and inexpensive method for oxidation of phenol, benzene, styrene and cyclohexene, having advantages over heterogeneous catalysis are its high activity and selectivity and short reaction times. Its major problem is its industrial application regarding principally the separation of the catalyst from the products.The size of the substrate has a significant effect on the conversion by encapsulated complexes such as in styrene oxidation. Therefore, it was established that steric effects of the substrates play a critical role in the poor reactive nature of the encapsulated complexes.In general, the percentage conversion decreased upon encapsulation of complexes in zeolite Y. All catalysts studied proved to be potential catalysts for the various oxidation reactions.It has been shown in this study that encapsulation can effectively improve product selectivity but requires a longer reaction time in most cases for maximum activity.Furthermore,oxovanadium complexes were more reactive than copper-based catalysts in all oxidation reactions tested in this study.A reaction mechanism study revealed that the activity of the encapsulated and neat complexes occurs through either formation of peroxovanadium (V) or hydroperoxidecopper(II) intermediate species.The studies in this thesis, therefore, conclude that the Cu(II) and V(IV) complexes encapsulated in Y-zeolite are active heterogeneous catalysts for the selective oxidation of various substrates. Encapsulation of the metal complexes in the super cages (-cages) of the zeolite matrix has the advantages of solid heterogeneous catalysts of easy separation and handling, ruggedness, thermostability, reusability (regeneration of the deactivated catalysts) as well as share many advantageous features of homogeneous catalysts.