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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.
251

Control of distributed energy storage and EVs in building communities

Zigga, Kweku, Nasir, Usman January 2023 (has links)
This study delves into the comparative operational effectiveness of non-coordinated, bottom-up, and top-down coordinated control models within Distributed Energy Storage Systems (DESS) and Electric Vehicle (EV) networks. Employing meticulous data analysis, this research evaluates power demand and supply dynamics within the infrastructure and buildings, aiming to optimize energy usage and storage. The analysis involves comprehensive steps: descriptive statistical breakdown, understanding energy patterns across buildings, and a comparative assessment of the control models. Visual representations and graphs aid in depicting energy patterns, emphasizing the distinctive characteristics and effectiveness of each control model. The findings reinforce the superiority of the top-down coordinated control model in managing supply-demand imbalances, echoing established literature.
252

[pt] MODELOS E APLICAÇÕES PARA SÉRIES TEMPORAIS HIERÁRQUICAS: ABORDAGENS DE RECONCILIAÇÃO ÓTIMA E PROPORÇÕES DE PREVISÃO / [en] MODELS AND APPLICATIONS TO HIERARCHICAL TIME SERIES: APPROACHES OF RECONCILIATION OPTIMAL AND FORECAST PROPORTIONS

THAISA DE FREITAS 30 August 2016 (has links)
[pt] Séries Temporais que podem ser organizadas em níveis de acordo com, por exemplo, o tipo de produto, região geográfica, classe de consumo, dentre outros, são chamadas de Séries Temporais Hierárquicas (ou agrupadas, quando possuem mais de uma variável de agregação). Informações referentes à previsão destas séries são fundamentais para a tomada de decisão seja no nível gerencial ou operacional de todo tipo de negócio. Para atender a essas informações, são utilizadas técnicas de previsão hierárquica, que têm como foco reduzir os custos e melhorar a acurácia da previsão. O objetivo deste trabalho é estudar abordagens para agregar/desagregar previsões feitas para Séries Temporais Hierárquicas ou Agrupadas. Como resultado do trabalho destaca-se a apresentação das abordagens que representam o estado da arte em previsão hierárquica: Reconciliação Ótima (também chamada de Combinação Ótima) e Top-Down baseada na Proporção das Previsões. Ainda referente aos resultados destaca-se a análise das diversas técnicas de previsão hierárquica encontradas na literatura aplicadas a duas séries clássicas do contexto brasileiro: a série agrupada de consumo de energia elétrica agregada por região do país e classe de consumo, e a série hierárquica de demanda de transporte aéreo representada pela variável RPK (Revenue Passenger Kilometers). O desempenho preditivo das abordagens foi avaliado com base na métrica MAPE, e o teste de Diebold-Mariano foi aplicado para verificar se a diferença no desempenho das abordagens novas e tradicionais é significativa. / [en] Time Series which can be arranged in levels according to, for example, the type of product, geography, consumption class, among others, are called Hierarchical Time Series (or grouped, if they have more than one aggregation variable). Information relating these series prediction is fundamental for decision-making at the management or operational level of all types of business. To meet these information, hierarchical forecasting techniques are used, which are focused on reducing costs and improving the accuracy of prediction. The objective of this work is to study approaches to aggregate / disaggregate predictions for Hierarchical or Grouped Time Series. As a result of the work there is the presentation of the approaches that represent the state of the art hierarchical forecast: Optimal Reconciliation approach (also called the Optimal Combination) and Top-Down Forecast Proportions approach. Still on the results highlight the analysis of the various hierarchical forecasting techniques found in the literature applied to two classic series of the Brazilian context: a grouped series of electricity consumption aggregated by region of the country and consumer class, and the hierarchical series air transport demand represented by the variable RPK (Revenue Passenger Kilometers). The predictive performance of the approaches was evaluated based on the metric MAPE and the Diebold-Mariano test was used to verify that the difference in performance of new and traditional approaches is significant.
253

Assessment of Urban Metabolism of Stockholm Royal Seaport : Through the Enhanced Economy Wide Material Flow Accounting Framework

Abrishami, Sina January 2020 (has links)
Material flows in Urban Metabolism play a key role for the purpose of building urban areas and growing the economy. There is lack of standard method for accounting of material flows within and across the boundaries of urban systems. This thesis aims to assess the Urban Metabolism of small-scale urban area through the application of the Economic Wide Material Flow Analysis and enhance the scope of the method by adding water flows, which could potentially become a basis for the development of the method in the future. First, the application of the Economic Wide Material Flow Analysis in urban areas was studied through a literature review and then the enhanced Economic Wide Material Flow Analysis was applied to Stockholm Royal Seaport using bottom-up data. Using bottom-up data resulted in detailed information, however, full comparison between urban areas was not possible due to data gaps. The results showed the importance of the method for enhancing Urban Metabolism analysis and amending resource management. Spotting available secondary and recycled resources in the socioeconomic system as a part of application of the method is beneficial to sustain the natural resources use. Since still the method is developing for small-scale urban areas, a mixture of this method and other recommended methods by having focus on data collection is suggested for integrating databases and comprehensive analysis. / Under de senaste decennierna har stadsområden expanderat snabbare än tidigare. Genom att öka människors tendens att bo i stora städer kommer naturresurser att behövas för att tillgodose stadsområdens växande behov. Materialflöden i stadsmetabolismen spelar en nyckelroll för att bygga miljövänligt och växande ekonomin. Det saknas en standardmetod för redovisning av materialflöden inom och över gränserna för stadssystem. Denna avhandling syftar till att utvärdera stadsmetabolismen genom att använda tillämpning av bred ekonomisk materialflödesredovisning och förbättra metodens omfattning genom att lägga till vatten- och genomströmningsflöden som potentiellt kan bli bas för utvecklingen av metoden i framtiden. Först studerades tillämpningen av ekonomiskt bred materialflödesredovisning i urbana områden genom litteraturöversikt och sedan tillämpades den förbättrade analysen av ekonomiskt bred materialflöde på Norra Djurgårdsstaden med hjälp av bottom-up data. Att använda bottom-up-data resulterade i detaljerad information, men fullständig jämförelse mellan stadsområden var inte möjlig på grund av dataklyftan Resultaten visade vikten av materialflödesredovisning för att förbättra urban metabolismanalys och ändra resurshantering. Att hitta tillgängliga sekundära och återvunna resurser i det socioekonomiska systemet som en del av tillämpningen av metoden är fördelaktigt för att upprätthålla användningen av naturresurser. Eftersom metoden fortfarande utvecklas för småskaliga stadsområden föreslås en blandning av denna metod och andra rekommenderade metoder såsom, livscykelbedömning, genom att fokusera på datainsamling för att integrera databas och omfattande analys.
254

Diagnosing L2 English Learners’ Listening comprehension abilities with Scripted and Unscripted Listening Texts

Carney, Nathaniel January 2018 (has links)
L2 listening research has moved toward a focus on understanding the process of listening. However, there are still few detailed studies of L2 listening that reveal learners’ comprehension processes when listening to scripted and unscripted listening texts. Studies in which such processing has been discussed have lacked detailed diagnoses of how bottom-up and top-down processing interactively affect listeners’ comprehension. This study was designed to show how listeners’ process and comprehend texts, with a focus on how their bottom-up and top-down processing either assist or impede their comprehension. In this study, a group of 30 L1 Japanese university English language learners’ listening abilities were diagnosed. The 30 participants were at three listening proficiency levels—high, mid, and low—based on TOEIC listening proficiency scores. The diagnostic procedure involved participants listening to two scripted and two unscripted listening texts and then reporting what they comprehended through three tasks—L1 oral recalls, L2 repetitions, and verbal reports. Other data was also collected in the study to relate the comprehension of listening texts to other important listening-related variables including listening proficiency, lexical knowledge, listening anxiety, study abroad experience, short-term phonological memory, and working memory. The main finding of the study was that miscomprehension of listening texts was invariably multi-causal, with a combination of both bottom-up and top-down factors leading to comprehension difficulty. Although not a new finding, the study offered more detail than current research about how bottom-up and top-down processing occur interactively. Regarding the overall difficulty of the listening texts, unscripted texts were more difficult to comprehend than scripted texts, and high-proficiency participants had fewer listening difficulties overall than mid- and low-proficiency participants. Quantitative and qualitative results revealed common processing difficulties among all participants due to L1-related phonological decoding issues (e.g., /l/ vs. /r/), connected speech, unknown lexis, and a lack of familiarity with unscripted speech hesitation phenomena (e.g., um, like). Qualitative transcript examples showed how top-down knowledge influenced misinterpretations of words and phrases interactively with bottom-up information, making inaccurate understandings of listening difficult to overcome. In addition to revealing participants’ difficulties and the severity of their comprehension difficulties, the diagnostic procedure showed common strengths—key words and phrases understood well by participants. High-frequency vocabulary and shorter utterances were both shown to be comprehended well. Finally, quantitative results in the study revealed relationships of participants’ listening comprehension with other important listening related variables. Listening proficiency and listening anxiety had strong relationships with listening comprehension of the listening texts. Working memory and short-term phonological memory had no relationship with listening text comprehension. Finally, study abroad experience showed a relationship with comprehension, but with many caveats, and listening vocabulary knowledge was not related with comprehension, but again, with numerous caveats to consider. Based on the results, theoretical and pedagogical implications were posed. Theoretical implications from the study relate to the understanding of four concerns in L2 listening research. Mainly, data in the study will aid researchers’ understanding of how L2 English listeners process speech interactively (i.e., with bottom-up and top-down information) for comprehension, how L2 English listeners experience connected speech, how L2 listeners deal with unknown lexis, and how L2 listeners experience difficulties with features of unscripted speech. Pedagogical implications of the study include the need for increased teacher and learner awareness of the complexity of L2 listening, the need to have learners to track their own listening development, and the need for teachers to expose learners to unscripted listening texts and make them familiar with features of unscripted speech. Finally, suggestions for further research are posed, including conducting diagnostics assessments of L2 listening with listeners of different L1s and with more varied proficiency levels, using different diagnostic procedures to examine L2 listening comprehension, and using more instruments to understand listening-related variables’ relationships with L2 listening comprehension. / Teaching & Learning
255

En insats olik andra : En kvalitativ studie om boendestödjares roll / A service unlike others : A qualitative study about the role of support in daily living workers

Jönis, Anna Ronja, Schött, Carolina January 2023 (has links)
The purpose of this study was to increase the knowledge of how social workers who work with support in daily living (SIDL) view their professional role, their work assignments and the obstacles and possibilities in their work. This study aims to answer what social workers within SIDL do in their work and how they view their role, what obstacles and possibilities they face, what the organizational conditions look like as well as how they experience SIDL has changed over time. Data was collected through 6 semi-structured interviews with social workers who work with SIDL. The interviews were inductively analyzed. New Public management (NPM) was later applied as a theoretical framework to better understand the results. Five themes have been identified: the shell of SIDL, the core of SIDL, a catch-all service, work environment and top-down management within the organization. The result of this study shows that pedagogy and flexibility are some of the core elements in SIDL, and that NPM is not compatible with these core elements. The results also indicate a stronger presence of NPM as governing logic over time.
256

Development of methodologies for memory management and design space exploration of SW/HW computer architectures for designing embedded systems / Ανάπτυξη μεθοδολογιών διαχείρισης μνήμης και εξερεύνησης σχεδιασμών σε αρχιτεκτονικές υπολογιστών υλικού/λογισμικού για σχεδίαση ενσωματωμένων συστημάτων

Κρητικάκου, Αγγελική 16 May 2014 (has links)
This PhD dissertation proposes innovative methodologies to support the designing and the mapping process of embedded systems. Due to the increasing requirements, embedded systems have become quite complex, as they consist of several partially dependent heterogeneous components. Systematic Design Space Exploration (DSE) methodologies are required to support the near-optimal design of embedded systems within the available short time-to-market. In this target domain, the existing DSE approaches either require too much exploration time to find near-optimal designs due to the high number of parameters and the correlations between the parameters of the target domain, or they end up with a less efficient trade-off result in order to find a design within acceptable time. In this dissertation we present an alternative DSE methodology, which is based on systematic creation of scalable and near-optimal DSE frameworks. The frameworks describe all the available options of the exploration space in a finite set of classes. A set of principles is presented which is used in the reusable DSE methodology to create a scalable and near-optimal framework and to efficiently use it to derive scalable and near-optimal design solutions within a Pareto trade-off space. The DSE reusable methodology is applied to several stages of the embedded system design flow to derive scalable and near-optimal methodologies. The first part of the dissertation is dedicated to the development of mapping methodologies for storing large embedded system data arrays in the lower layers of the on-chip background data memory hierarchy, and the second part to the DSE methodologies for the processing part of SW/HW architectures in embedded systems including the foreground memory systems. Existing mapping approaches for the background memory part are either enumerative, symbolic/polyhedral and worst case (heuristics) approximations. The enumerative approaches require too much exploration time, the worst case approximation lead to overestimation of the storage requirements, whereas the symbolic/polytope approaches are scalable and near-optimal for solid and regular iteration spaces. By applying the new reusable DSE methodology, we have developed an intra-signal in-place optimization methodology which is scalable and near-optimal for highly irregular access schemes. Scalable and near-optimal solutions for the different cases of the proposed methodology have been developed for the cases of non-overlapping and overlapping store and load access schemes. To support the proposed methodology, a new representation of the array access schemes, which is appropriate to express the irregular shapes in a scalable and near-optimal way, is presented. A general pattern formulation has been proposed which describes the access scheme in a compact and repetitive way. Pattern operations were developed to combine the patterns in a scalable and near-optimal way under all the potential pattern combination cases, which may exist in the application under study. In the processing oriented part of the dissertation, a DSE methodology is developed for mapping instance of a predefined target application domain onto a partially fixed architecture platform template, which consists of one processor core and several custom hardware accelerators. The DSE methodology consists of uni-directional steps, which are implemented through parametric templates and are applied without costly design iterations. The proposed DSE methodology explores the space by instantiating the steps and propagating design constraints which prune design options following the steps ordering. The result is a final Pareto trade-off curve with the most relevant near-optimal designs. As the scheduling and the assignment are the major tasks of both the foreground and the datapath, near-optimal and scalable techniques are required to support the parametric templates of the proposed DSE methodology. A framework which describes the scheduling and assignment of the scalars into the registers and the scheduling and assignment of the operation into the function units of the data path is developed. Based on the framework, a systematic methodology to arrive at parametric templates for scheduling and assignment techniques which satisfy the target domain constraints is developed. In this way, a scalable parametric template for scheduling and assignment tasks is created, which guarantees near-optimality for the domain under study. The developed template can be used in the Foreground Memory Management step and Data-path mapping step of the overall design flow. For the DSE of the domain under study, near-optimal results are hence achieved through a truly scalable technique. / Η παρούσα διδακτορική διατριβή προτείνει καινοτόμες μεθοδολογίες για τον σχεδιασμό και τη διαδικασία απεικόνισης σε ενσωματωμένα συστημάτα. Λόγω των αυξανόμενων απαιτήσεων, τα ενσωματωμένα συστήματα είναι αρκετά περίπλοκα, καθώς αποτελούνται από πολλά και εν μέρει εξαρτώμενα ετερογενή στοιχεία. Συστηματικές μεθοδολογίες για την εξερεύνηση του χώρου λύσεων (Design Space Exploration – DSE) απαιτούνται σχεδόν βέλτιστες σχεδιάσεις ενσωματωμένων συστημάτων εντός του διαθέσιμου χρονου. Οι υπάρχουσες DSE μεθοδολογίες απαιτούν είτε πάρα πολύ χρόνο εξερεύνησης για να βρουν τους σχεδόν βέλτιστους σχεδιασμούς, λόγω του μεγάλου αριθμού των παραμέτρων και τις συσχετίσεις μεταξύ των παραμέτρων, ή καταλήγουν με ένα λιγότερο βέλτιστο σχέδιο, προκειμένου να βρειθεί ένας σχεδιασμός εντός του διαθέσιμου χρόνου. Στην παρούσα διδακτορική διατριβή παρουσιάζουμε μια εναλλακτική DSE μεθοδολογία, η οποία βασίζεται στη συστηματική δημιουργία επεκτάσιμων και σχεδόν βέλτιστων DSE πλαισίων. Τα πλαίσια περιγράφουν όλες τις διαθέσιμες επιλογές στο χώρο εξερεύνησης με ένα πεπερασμένο σύνολο κατηγοριών. Ένα σύνολο αρχών χρησιμοποιείται στην επαναχρησιμοποιήούμενη DSE μεθοδολογία για να δημιουργήσει ένα επεκτάσιμο και σχεδόν βέλτιστο DSE πλαίσιο και να χρησιμοποιήθεί αποτελεσματικά για να δημιουργήσει επεκτάσιμες και σχεδόν βέλτιστες σχεδιαστικές λύσεις σε ένα Pareto Trade-off χώρο λύσεων. Η DSE μεθοδολογία εφαρμόζεται διάφορα στάδια της σχεδιαστικής ροής για ενσωματωμένα συστήματα και να δημιουργήσει επεκτάσιμες και σχεδόν βέλτιστες μεθοδολογίες. Το πρώτο μέρος της διατριβής είναι αφιερωμένο στην ανάπτυξη των μεθόδων απεικόνισης για την αποθήκευση μεγάλων πινάκων που χρησιμοποιούνται στα ενσωματωμένα συστήματα και αποθηκεύονται στα χαμηλότερα στρώματα της on-chip Background ιεραρχία μνήμης. Το δεύτερο μέρος είναι αφιερωμένο σε DSE μεθοδολογίες για το τμήμα επεξεργασίας σε αρχιτεκτονικές λογισμικού/υλικού σε ενσωματωμένα συστήματα, συμπεριλαμβανομένων των συστημάτων της προσκήνιας (foreground) μνήμης. Υπάρχουσες μεθοδολογίες απεικόνισης για την Background μνήμης είτε εξονυχιστικές, συμβολικές/πολυεδρικές και προσεγγίσεις με βάση τη χειρότερη περίπτωση. Οι εξονυχιστικές απαιτούν πάρα πολύ μεγάλο χρόνο εξερεύνησης, οι προσεγγίσεις οδηγούν σε υπερεκτίμηση των απαιτήσεων αποθήκευσης, ενώ οι συμβολικές είναι επεκτάσιμη και σχεδόν βέλτιστές μονο για τακτικούς χώρους επαναλήψεων. Με την εφαρμογή της προτεινόμενης DSE μεθοδολογίας αναπτύχθηκε μια επεκτάσιμη και σχεδόν βέλτιστη μεθοδολγοία για την εύρεση του αποθηκευτικού μεγέθους για τα δεδομένα ενός πίνακα για άτακτους και για τακτικούς χώρους επαναλήψεων. Προτάθηκε μια νέα αναπαράσταση των προσπελάσεων στη μνήμη, η οποία εκφράζει τα ακανόνιστα σχήματα στο χώρο επεναλήψεων με επακτάσιμο και σχεδόν βέλτιστο τρόπο. Στο δεύτερο τμήμα της διατριβής, μια DSE μεθοδολογία αναπτύχθηκε για το σχεδιασμό ενός προκαθορισμένου τομέα από εφαρμογές σε μια μερικώς αποφασισμένη αρχιτεκτονική πλατφόρμα, η οποία αποτελείται από ένα πυρήνα επεξεργαστή και αρκετούς συνεπεξεργαστές. Η DSE μεθοδολογία αποτελείται από μονής κατεύθυνσης βήματα, τα οποία υλοποιούνται μέσω παραμετρικών πλαισίων και εφαρμόζονται αποφέυγοντας τις δαπανηρές επαναλήψεις κατά τον σχεδιασμό. Η προτεινόμενη DSE μεθοδολογία εξερευνά το χώρο βρίσκοντας στιγμιότυπα για καθε βήμα και διαδίδονατς τις αποφάσεις μεταξύ βημάτων. Με αυτό το τρόπο κλαδεύουν τις επιλογές σχεδιασμού στα επόμενα βήματα. Το αποτέλεσμα είναι μια Pareto καμπύλη. Ένα DSE πλαίσιο προτάθηκε που περιγράφει τις τεχνικές χρονοπρογραμματισμού και ανάθεσης πόρων των καταχωρητών και των μονάδων εκτέλεσης του συστήματος. Προτάθηκε μια μεθοδολογία για να δημιουργεί σχεδόν βέλτιστα και επεκτάσιμα παραμετρικά πρότυπα για τον χρονοπρογραμματισμό και την ανάθεση πόρων που ικανοποιεί τους περιορισμούς ενός τομέα εφαρμογών.
257

Étude intracrânienne sur les mécanismes cérébraux permettant la reconnaissance d’objets

Bertrand, Josie-Anne 06 1900 (has links)
La reconnaissance d’objets est une tâche complexe au cours de laquelle le cerveau doit assembler de manière cohérente tous les éléments d’un objet accessible à l’œil afin de le reconnaître. La construction d’une représentation corticale de l’objet se fait selon un processus appelé « bottom-up », impliquant notamment les régions occipitales et temporales. Un mécanisme « top-down » au niveau des régions pariétales et frontales, facilite la reconnaissance en suggérant des identités potentielles de l’objet à reconnaître. Cependant, le mode de fonctionnement de ces mécanismes est peu connu. Plusieurs études ont démontré une activité gamma induite au moment de la perception cohérente de stimuli, lui conférant ainsi un rôle important dans la reconnaissance d’objets. Cependant, ces études ont utilisé des techniques d’enregistrement peu précises ainsi que des stimuli répétitifs. La première étude de cette thèse vise à décrire la dynamique spatio-temporelle de l’activité gamma induite à l’aide de l’électroencéphalographie intracrânienne, une technique qui possède des résolutions spatiales et temporelles des plus précises. Une tâche d’images fragmentées a été conçue dans le but de décrire l’activité gamma induite selon différents niveaux de reconnaissance, tout en évitant la répétition de stimuli déjà reconnus. Afin de mieux circonscrire les mécanismes « top-down », la tâche a été répétée après un délai de 24 heures. Les résultats démontrent une puissante activité gamma induite au moment de la reconnaissance dans les régions « bottom-up ». Quant aux mécanismes « top-down », l’activité était plus importante aux régions occipitopariétales. Après 24 heures, l’activité était davantage puissante aux régions frontales, suggérant une adaptation des procédés « top-down » selon les demandes de la tâche. Très peu d’études se sont intéressées au rythme alpha dans la reconnaissance d’objets, malgré qu’il soit bien reconnu pour son rôle dans l’attention, la mémoire et la communication des régions neuronales distantes. La seconde étude de cette thèse vise donc à décrire plus précisément l’implication du rythme alpha dans la reconnaissance d’objets en utilisant les techniques et tâches identiques à la première étude. Les analyses révèlent une puissante activité alpha se propageant des régions postérieures aux régions antérieures, non spécifique à la reconnaissance. Une synchronisation de la phase de l’alpha était, quant à elle, observable qu’au moment de la reconnaissance. Après 24 heures, un patron similaire était observable, mais l’amplitude de l’activité augmentait au niveau frontal et les synchronies de la phase étaient davantage distribuées. Le rythme alpha semble donc refléter des processus attentionnels et communicationnels dans la reconnaissance d’objets. En conclusion, cette thèse a permis de décrire avec précision la dynamique spatio-temporelle de l’activité gamma induite et du rythme alpha ainsi que d’en apprendre davantage sur les rôles potentiels que ces deux rythmes occupent dans la reconnaissance d’objets. / Recognizing objects is a complex task requiring the brain to assemble visual information in such a way that coherent perception can happen. Building a visual cerebral representation is done through a bottom-up process, involving mainly occipital and temporal areas. A top-down mechanism from parietal and frontal areas, is thought to facilitate recognition by taking into account expectations and generating possible candidates. However, the precise mechanisms by which all these processes are done are still unclear. Studies investigating induced gamma response were able to link this activity to coherent perception of objects, suggesting a significant role of this activity in object recognition. However, these studies used imprecise recording techniques and stimuli repetition. The first study of this thesis aimed at describing with more precision the induced gamma activity using intracranial encephalography and a fragmented images paradigm in which only new stimuli are presented. Moreover, the task was presented again 24 hours later to circumscribe top-down mechanisms. Results show that the induced gamma activity is highest at recognition in regions involved in bottom-up processes. Top-down mechanism involved occipito-parietal areas when images were presented for the first time. When images were presented again 24 hours later, frontal areas mediated top-down facilitation, suggesting that top-down mechanisms vary according to task demand. Alpha rhythm has been less clearly related to visual perception, but is nevertheless well known to be involved in attention, memory and long-distance brain communication. The second study of this thesis investigated the role of alpha rhythm in object recognition, using the same technique and task as in the first study. Time-frequency analysis revealed a strong alpha activity unspecific to recognition, which was propagating from posterior to anterior regions. Phase coherence analysis, however, showed significant phase synchronisation specific to recognition. A similar pattern of alpha activity was found 24 hours later. However, the activity was stronger in frontal regions and the phase synchronisation was more distributed. Alpha rhythm is thus thought to be involved in attentional and communicational mechanisms of object recognition. In conclusion, this thesis was able to describe the precise spatio-temporal dynamics of induced gamma and alpha activity and suggest potential roles of these rhythms in response to object recognition.
258

Estratégia atencional para busca visual e reconhecimento invariante de objetos baseada na integração de características bottom-up e top-down / Attentional strategy for visual search and invariant object recognition based on bottom-up and top-down feature integration

Neves, Evelina Maria de Almeida 30 June 2000 (has links)
Uma das tarefas básicas dos mecanismos atencionais é decidir qual a localização dentro do campo visual, em que devemos prestar atenção primeiro. Um objeto que contenha características distintas, tais como orientação, forma, cor, tamanho, brilho, textura, etc. diferentes, pode atrair a atenção de uma maneira \"bottom-up\". A informação \"top-down\" baseia-se no conhecimento prévio e tem uma grande influência nas localizações atendidas. Inspirado nos mecanismos da Atenção Visual Humana, embora sem a pretensão de simulá-la, este trabalho prevê o desenvolvimento de uma nova metodologia que integra os dois tipos de informações: \"bottom-up\" e \"top-down\". Características \"bottom-up\" são geradas a partir de Momentos e essas informações são utilizadas em mapas de saliência, enquanto que um conhecimento prévio é utilizado para gerar pistas \"top-down\". Neste trabalho, desenvolveu-se uma metodologia específica para a busca e o reconhecimento visual em cenas com múltiplos objetos, utilizando para isso uma rede \"fuzzy\" contendo três subsistemas \"fuzzy\". Dada uma imagem de entrada, o objetivo consiste em se detectar regiões que possam conter informações mais significativas, a fim de que se possa guiar e restringir processamentos mais complexos. A inclusão de mecanismos de atenção (seleção de uma região de interesse dentro da imagem) é de fundamental importância pois os resultados obtidos pelo método podem ser usados para controlar a aquisição da imagem de uma maneira dinâmica. O modelo proposto está estruturado em três estágios principais: O primeiro estágio consiste em se segmentar os objetos e extrair características globais dos mesmos baseadas principalmente na teoria dos momentos, tais como tamanho, orientação, formato e distância e também média de nível de cinza. Por intermédio da comparação de um objeto com os outros presentes na cena, características \"bottom-up\" de conspicuidade são usadas para guiar a atenção ao objeto mais diferente. Por intermédio do uso da lógica \"fuzzy\" é possível inferir com grande flexibilidade algumas regras de decisão baseadas nos princípios de percepção visual tais como as leis Gestalt. O segundo estágio consiste de um subsistema \"fuzzy top-down\" que combina diferentes características de acordo com a relevância das mesmas em diferentes tarefas. Finalmente, o terceiro estágio consiste de um subsistema \"fuzzy\" que integra as informações obtidas dos subsistemas anteriores e fornece um índice geral de saliência, e indica a provável localização do objeto a ser reconhecido. A nova abordagem foi testada com objetos geométricos levando-se em consideração as características que atraem a atenção dos serem humanos / One of the basic tasks assigned to the human attentional mechanisms is to decide which location in the visual field we must pay attention first. An object containing distinctive features (such as different orientation, shape, color, size, shine, texture, etc.) can attract attention in a bottom-up way. Top-down information is based on the previous knowledge and has a large influence on the attended locations. Inspired on human visual attention mechanisms, although it doesn\'t want simulate it, this work presents a new methodology to integrate two different kind of information: bottom-up and top-down. Bottom-up features are obtained from Moment Theory and this information is used in salience maps, while a previous knowledge is used to create top-down hints. In this work, an specific methodology to visual search and recognition was developed to be applied to scenes containing multiple objects by a fuzzy net with three fuzzy subsystems. The aim of this methodology is to detect regions that may contain the most significant information, in order to guide and to restrict most complex processing. The inclusion of attentional mechanisms (the selection of a region of interest in the image) is fundamental and can be used to control the image acquisition in a dynamic way. The proposed model is structured in three main stages. The first stage segments the objects and extracts global features of them, based on the Moment Theory such as size, orientation, shape and distance and gray level average. By comparing one object with the other ones present in the scene, bottom-up features of conspicuity are used to guide the attention to the most different object. The Fuzzy Logic allows us to infer with great flexibility some of decision rules based on the visual perception principles such as the Gestalt Laws. The second stage is a top-down fuzzy subsystem that combines different features according to the relevance of them in different tasks. Finally, the third stage is a fuzzy subsystem that integrates the information obtained from the previous sub-systems and gives us a general salience index. The new methodology was tested in geometrical objects considering the feature that attracts attention to human beings
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"Det är inte bara folkvalda politiker som utövar offentlig makt" : En jämförande studie gällande främjande av integration i fem kommuner i Stockholms län / "It is not just elected representatives that exercise public power" : A comparative study of integration in five municipalities in Stockholm County

Degard, Emelie, Abdulla, Maya January 2009 (has links)
<p>Based on different integration policies, we aim to examine how five municipalities in Stockholm County are working to promote integration at a local level with focus on voter participation and to some extent, representativeness among foreign-born. Statistics provided by SCB shows that foreign-born tends to vote to a lesser extent than those born in Sweden. Further, we aim to examine the implementation of two policy documents established at a national level concerning integration in contrast to policy documents established at a local level in each different municipality. Further, we aim to examine summaries of actions taken in response to the local integration programs, as well as personal interviews. Each municipality will be considered separately, but we thus seek to make a comparative study. The study will be based on a qualitative approach. The implementation process of both central and local policy decisions concerning the promotion of integration will also be discussed in terms of two existing theories of implementation, based on two different perspectives. The result shows that interaction between different participants, such as local officials and politicians, is of importance for the implementation process. All of the studied municipalities have taken some actions in order to implement their goals concerning integration.</p>
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Το μοντέλο των σκληρών και μαλακών οξέων και βάσεων ως εργαλείο στη χημεία των μοριακών ετερομεταλλικών μαγνητών / The principle of hard and soft acids and bases as a tool in the chemistry of molecular heterometallic magnets

Λαδά, Ζωή 09 October 2014 (has links)
Τα ομομεταλικά σύμπλοκα που περιέχουν αποκλειστικά 3d μεταλλοϊόντα, καθώς και τα ετερομεταλλικά σύμπλοκα 3d/4f μεταλλοϊόντων αποτελούν σήμερα πόλο έλξης για τους ανόργανους χημικούς, λόγω των σημαντικών μαγνητικών, οπτικών και καταλυτικών τους ιδιοτήτων. Η χημεία των πολυπυρηνικών συμπλόκων (πλειάδων) των μετάλλων μετάπτωσης της 1ης Σειράς αποτελεί σήμερα ερευνητικό πεδίο αιχμής, καθώς προκύπτει από την αλληλοεπικάλυψη των επιστημών της Χημείας, της Βιολογίας και της Φυσικής, βρίσκοντας εφαρμογές σε τομείς όπως η Βιοανόργανη Χημεία, η Χημεία των Μοριακών Υλικών και η Νανοτεχνολογία. Ιδιαίτερο ενδιαφέρον παρουσιάζουν οι μαγνητικές ιδιότητες των μοριακών πλειάδων μετά την ανακάλυψη του φαινομένου του Μονομοριακού Μαγνητισμού. Μαγνήτες Μοναδικού Μορίου, ΜΜΜ (Single Molecule Magnets, SMMs) είναι μοριακές πλειάδες οι οποίες μπορούν να διατηρούν το μαγνητικό προσανατολισμό τους, απουσία ενός μαγνητικού πεδίου, κάτω από μια συγκεκριμένη θερμοκρασία. Οι ΜΜΜ αντιπροσωπεύουν τη μικρότερη συσκευή αποθήκευσης πληροφοριών με ποικιλία δυνητικών εφαρμογών. Πολλοί ΜΜΜ των 3d μετάλλων έχουν υψηλό ολικό σπιν στη θεμελιώδη κατάσταση, αλλά υστερούν σημαντικά στο θέμα της μαγνητικής ανισοτροπίας, όπως αυτή αντικατοπτρίζεται στη μικρή τιμή της παραμέτρου σχάσης μηδενικού πεδίου D. Τα λανθανίδια διαδραματίζουν έναν ιδιαίτερο ρόλο στο Μαγνητισμό, εξαιτίας της μεγάλης μαγνητικής ροπής τους, και στις περισσότερες των περιπτώσεων, λόγω της τεράστιας μαγνητικής τους ανισοτροπίας. Στην τρισθενή τους όμως οξειδωτική κατάσταση, που είναι και η πιο σταθερή, παρουσιάζουν το μειονέκτημα της πολύ ασθενούς αλληλεπίδρασης ανταλλαγής μεταξύ των μεταλλοϊόντων, ως αποτέλεσμα της αποτελεσματικής προάσπισης των ασυζεύκτων ηλεκτρονίων των 4f τροχιακών. Το γεγονός αυτό οδήγησε στη διερεύνηση συστημάτων που συνδυάζουν 4f ιόντα με άλλα παραμαγνητικά είδη, όπως οργανικές ρίζες ή 3d ιόντα. Έτσι, η ταυτόχρονη ύπαρξη των τρισθενών λανθανιδίων (LnIII) και 3d μεταλλοϊόντων μπορεί να βελτιώσει το Μονομοριακό Μαγνητισμό των πλειάδων ένταξης οδηγώντας σε μαγνητικές ιδιότητες διαφορετικές από αυτές των 3d πλειάδων. Η Διπλωματική Εργασία μας στα πλαίσια του Μεταπτυχιακού Διπλώματος Ειδίκευσης «Αναλυτική Χημεία και Νανοτεχνολογία» αφορά τη χημεία των πλειάδων των 3d/4f- μεταλλοϊόντων. Στις προσπάθειές μας να συνθέσουμε ετερομεταλλικές πλειάδες Co ή Cu/LnΙΙΙ με υποκαταστάτες οξίμες (2-πυρίδυλο οξίμες, 2,4-πεντανιοδιόνη διοξίμη) και τη δι-2-πυρίδυλο κετόνη και τα παράγωγά της, απομονώσαμε και χαρακτηρίσαμε οικογένειες συμπλόκων μεταβάλλοντας κάθε φορά παραμέτρους της αντίδρασης, όπως τη φύση του οργανικού υποκαταστάτη, τον διαλύτη της αντίδρασης, την πηγή των μεταλλοϊόντων, τη θερμοκρασία, την πίεση, κ.α. Ως συνθετική πορεία χρησιμοποιήσαμε την “bottom-up” προσέγγιση. Η στρατηγική “bottom-up” χρησιμοποιεί τις χημικές ιδιότητες των διακριτών μορίων για να προκαλέσει: Α) Αυτο-οργάνωση ή αυτο-συναρμολόγηση σε μια χρήσιμη διαμόρφωση. Β) Οργάνωση σε συγκεκριμένη θέση. Η στρατηγική αυτή χρησιμοποιείται για τις έννοιες της μοριακής αυτο-οργάνωσης ή/και της μοριακής αναγνώρισης. Σε ευρύτερο επίπεδο, δηλαδή η “bottom-up” τεχνική δυνητικά μπορεί να παράγει παράλληλες συσκευές με πολύ φθηνότερους τρόπους σε σχέση με την “top-down” μέθοδο που χρησιμοποιείται ευρέως στη σύνθεση τεχνολογικού ενδιαφέροντος συσκευών. Η μοριακή αυτή προσέγγιση ξεκινά με χρήση πηγών ανεξάρτητων ατόμων ή μικρών μορίων για τη σύνθεση μεγάλων μοριακών νανοδομών με επιθυμητές και στοχευμένες ιδιότητες, με αποτέλεσμα να αναπτύσσεται το πεδίο της Ναντεχνολογίας. Δύο γενικές προσεγγίσεις για τη σύνθεση συμπλόκων Co ή Cu/LnIII είναι: η στρατηγική που βασίζεται στη χρησιμοποίηση «μεταλλικών συμπλόκων ως υποκαταστατών» και η στρατηγική που βασίζεται στην «απλή ανάμιξη των συστατικών». Στην παρούσα Διπλωματική Εργασία εφαρμόζεται η δεύτερη κατά σειρά προσέγγιση για την παρασκευή των παρακάτω συμπλόκων ενώσεων: [CoIII {(py)C(Η)NO}2{(py)C(Η)NOH}](ClO4) [CoIII2DyIII{(py)C(Η)NO}6(H2O)(DMF)](ClO4)3.3.2H2O [CoIII2GdIII{(py)C(Η)NO}6(H2O)(DMF)](ClO4)3.3.2H2O [CoIII2DyIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIII2GdIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIII2SmIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIII2TbIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIIIDyIII{(py)C(Ph)NO}3(NO3)3] [CoIIIEuIII{(py)C(Ph)NO}3(NO3)3] [CoIIISmIII{(py)C(Ph)NO}3(NO3)3].0.3MeOH [CoIIITbIII{(py)C(Ph)NO}3(NO3)3].0.3MeOH [CoIIIGdIII{(py)C(Ph)NO}3(NO3)3].0.3MeOH [CoIII2Na{(py)C(Η)NO}6].(OMe) [CoIII2DyIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2GdIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2TbIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2PrIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2YIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [Cu2(diba)4(κινοξαλίνη)]n [Cu3Dy2{(py)2CO2}{(py)2CO(OMe)}3{(py)2CO(OEt)}(NO3)4(H2O)2](ClO4)(OH) [Cu6{(py)2CO(OMe)}6(NO3)2](ClO4)4 [Cu3{(py)2C(OMe)(OH)}2{(py)2C(OMe)O}2(ClO4)2] (ClO4)2 .2MeOH [Cu{(py)2C(OH){CH2COCH3)}2](NO3)2.2H2O Οι δομές των συμπλόκων προσδιορίσθηκαν με Κρυσταλλογραφία Ακτίνων Χ Μονοκρυστάλλου. Σε επιλεγμένα σύμπλοκα από αυτά που συνθέσαμε μελετώνται οι μαγνητικές τους ιδιότητες. Τα σύμπλοκα χαρακτηρίστηκαν με φυσικές και φασματοσκοπικές τεχνικές. Τα δεδομένα μελετήθηκαν σε σχέση με τις γνωστές δομές των συμπλόκων και των τρόπων ένταξης των υποκαταστατών. / Homometallic complexes which contain exclusively 3d metal ions and heterometallic complexes with 3d/4f metal ions attract, nowdays, the intense interest of inorganic chemists, due to their important magnetic, optical and catalytical properties. The chemistry of polynuclear complexes (clusters) of the 1st row transition metals is a cutting-edge research area, since combines the sciences of Chemistry, Biology and Physics with applications in the fields of Bioinorganic Chemistry, Chemistry of Molecular Materials and Nanotechnology. After the discovery of the phenomenon of Single Molecule Magntesism, the magnetic properties of molecular clusters are a growning research field. Single Molecule Magnets (SMMs) are molecular clusters which can retain their magnetic orientation, in the absence of a magnetic field, below a certain temperature. SMMs represent the smallest information storage devices with multiple potential applications. Many SMMs of 3d metals exhibit high total spin in the ground state, but their disadvantage is the low value of Zero Field Splitting (ZFS) parameter, D. Lanthanides play an important role in Magnetism, due to their large spin and in most cases huge magnetic anisotropy. In their trivalent oxidation state, which is the most stable, they have the disadvantage of the very weak exchange interactions between the metal ions, as a result of the efficient shielding of unpaired 4f electrons. This fact has led to the investigation of systems combining 4f-metal ions with other paramagnetic species, such as organic radicals or 3d-metal ions. Thus, the simultaneous presence of trivalent lanthanides (LnIII) and 3d metal ions can improve the Single Molecule Magnetism behavior of coordination clusters leading to magnetic properties different from those of 3d clusters. Our Diploma Work in the context of the M.Sc. in “Analytical Chemistry and Nanotechnology” concerns the chemistry of 3d/4f clusters. In our efforts to synthesize heterometallic clusters of Co or Cu/LnIII with oximes (2-pyridyl oximes, 2,4-pentanedione dioxime) and di-2-pyridyl ketone as ligands, we have isolated and characterized new families of complexes, studying various reaction parameters, such as the nature of the organic ligand, the solvent of the reaction, the source of the metal ions, the temperature, the pressure etc. As synthetic route, we have used the “bottom-up” approach. The “bottom-up” approach uses the chemical properties of discrete molecules in order to cause: a) Self-organization or Self-assembly in an interesting configuration. b) Assembly with a specific stereochemistry. This strategy is used for the concepts of molecular self-organization and/or molecular recognition. Hence in a broader sense, the “bottom-up” approach can produce potential applications in devices with cheaper ways in relation to the “top-down” approach which is used widely for the synthesis of devices with technological interest. This molecular approach begins with the use of independent sources of atoms or small molecules for the synthesis of large molecular nanostructures with preferential and targeted properties, developing though the field of Nanotechnology. Two general synthetic approaches for the synthesis of Co or Cu/LnIII complexes are: the strategy which is based on the use of “metal complexes as ligands” and the strategy based on the “simple mixing of components”. In this Diploma Work we have used the second approach for the synthesis of the below mentioned complexes: [CoIII {(py)C(Η)NO}2{(py)C(Η)NOH}](ClO4) [CoIII2DyIII{(py)C(Η)NO}6(H2O)(DMF)](ClO4)3.3.2H2O [CoIII2GdIII{(py)C(Η)NO}6(H2O)(DMF)](ClO4)3.3.2H2O [CoIII2DyIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIII2GdIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIII2SmIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIII2TbIII{(py)C(Η)NO}6(H2O)(MeOH)](ClO4)3.3.2H2O [CoIIIDyIII{(py)C(Ph)NO}3(NO3)3] [CoIIIEuIII{(py)C(Ph)NO}3(NO3)3] [CoIIISmIII{(py)C(Ph)NO}3(NO3)3].0.3MeOH [CoIIITbIII{(py)C(Ph)NO}3(NO3)3].0.3MeOH [CoIIIGdIII{(py)C(Ph)NO}3(NO3)3].0.3MeOH [CoIII2Na{(py)C(Η)NO}6].(OMe) [CoIII2DyIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2GdIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2TbIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2PrIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [CoIII2YIII2{(py)C(Η)NO}4(piv)4(NO3)4].2MeCN [Cu2(diba)4(quinoxaline)]n [Cu3Dy2{(py)2CO2}{(py)2CO(OMe)}3{(py)2CO(OEt)}(NO3)4(H2O)2](ClO4)(OH) [Cu6{(py)2CO(OMe)}6(NO3)2](ClO4)4 [Cu3{(py)2C(OMe)(OH)}2{(py)2C(OMe)O}2(ClO4)2] (ClO4)2 .2MeOH [Cu{(py)2C(OH){(CH2COCH3)}2](NO3)2.2H2O The structures of the complexes have been solved with Single Crystal X-ray Crystallography. The magnetic properties of selected compounds are investigated. The complexes have been characterized by several physical and spectroscopic techniques. The data are discussed in terms of the known structures of the complexes and the coordination modes of the ligands.

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