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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.
81

Link Quality in Wireless Sensor Networks / Qualité des liens dans les réseaux de capteurs sans fil : Conception de métriques de qualité de lien pour réseaux de capteurs sans fil en intérieur et à large échelle

Bildea, Ana 19 November 2013 (has links)
L'objectif de la thèse est d'étudier la variation temporelle de la qualité des liens dans les réseaux de capteurs sans fil à grande échelle, de concevoir des estimateurs permettant la différenciation, à court terme et long terme, entre liens de qualité hétérogène. Tout d'abord, nous étudions les caractéristiques de deux paramètres de la couche physique: RSSI (l'indicateur de puissance du signal reçu) et LQI (l'indicateur de la qualité de liaison) sur SensLab, une plateforme expérimentale de réseau de capteurs à grande échelle situé à l'intérieur de bâtiments. Nous observons que le RSSI et le LQI permettent de discriminer des liens de différentes qualités. Ensuite, pour obtenir un estimateur de PRR, nous avons approximé le diagramme de dispersion de la moyenne et de l'écart-type du LQI et RSSI par une fonction Fermi-Dirac. La fonction nous permet de trouver le PRR à partir d'un niveau donné de LQI. Nous avons évalué l'estimateur en calculant le PRR sur des fenêtres de tailles variables et en le comparant aux valeurs obtenues avec l'estimateur. Par ailleurs, nous montrons en utilisant le modèle de Gilbert-Elliot (chaîne de Markov à deux états) que la corrélation des pertes de paquets dépend de la catégorie de lien. Le modèle permet de distinguer avec précision les différentes qualités des liens, en se basant sur les probabilités de transition dérivées de la moyenne et de l'écart-type du LQI. Enfin, nous proposons un modèle de routage basé sur la qualité de lien déduite de la fonction de Fermi-Dirac approximant le PRR et du modèle Markov Gilbert-Elliot à deux états. Notre modèle est capable de distinguer avec précision les différentes catégories de liens ainsi que les liens fortement variables. / The goal of the thesis is to investigate the issues related to the temporal link quality variation in large scale WSN environments, to design energy efficient link quality estimators able to distinguish among links with different quality on a short and a long term. First, we investigate the characteristics of two physical layer metrics: RSSI (Received Signal Strength Indication) and LQI (Link Quality Indication) on SensLAB, an indoor large scale wireless sensor network testbed. We observe that RSSI and LQI have distinct values that can discriminate the quality of links. Second, to obtain an estimator of PRR, we have fitted a Fermi-Dirac function to the scatter diagram of the average and standard variation of LQI and RSSI. The function enables us to find PRR for a given level of LQI. We evaluate the estimator by computing PRR over a varying size window of transmissions and comparing with the estimator. Furthermore, we show using the Gilbert-Elliot two-state Markov model that the correlation of packet losses and successful receptions depend on the link category. The model allows to accurately distinguish among strongly varying intermediate links based on transition probabilities derived from the average and the standard variation of LQI. Finally, we propose a link quality routing model driven from the F-D fitting functions and the Markov model able to discriminate accurately link categories as well as high variable links.
82

Účetnictví zásob ve vybrané výrobní společnosti v oboru elektrotechniky, komparace účtování v obdobném podniku německé provenience / Inventory bookkeeping in a selected manufacturing firm in field of electrotechnics, comparison of bookkeeping with similar company of german provenance

VOMÁČKOVÁ, Eva January 2009 (has links)
A topic of my graduation theses is "Inventory bookkeeping in a selected manufacturing firm in field of electrotechnics, comparison of bookkeeping with similar company of german provenance". An aim of this graduation theses is to analyse the system of inventory bookkeeping in the manufacturing firm and to compare it with inventory bookkeping in similar companies in the Czech Republic and Germany. The main attention in practical part is dedicated to the method and the procedure of inventory bookkeeping in a given company. I analyse the acquisition of inventory from the Czech Republic and from Germany, its entry in a stock, delivery ex stock, sale of inventory in the Czech Republic and in Germany and I refer to bookkeeping in a given accounting entity. The accounting entity keeps accounts of inventory according to the valid regulations, nevertheless I found some bookkeeping operations, which could be solved in a different way. The partial aim of my graduation theses is to point out to different method of inventory bookkeeping in the Czech Republic and in Germany and currently introduce the bookkeeping words of art in german language. By the comparison of inventory bookkeeping according to german and czech bookkeeping I found many agreements, but I made out some more or less substantial differences. The graduation theses confirms that the bookeeping in the Czech Republic is mounting to the bookkeeping in Germany. This arises from performed comparison of accounting procedure by inventory bookkeeping in the Czech Republic and in Germany. Considering the development of international bookkeeping harmonization we can say, that the czech and german bookkeeping will develop in the same way and they will mount to each other.
83

Energy-aware localization based on an optimized anchor deployment in wireless sensor networks

El Houssaini, Dhouha 16 January 2023 (has links)
Various applications of Wireless Sensor Networks (WSNs) require accurate localization of sensor nodes. The quantity and locations of anchor nodes, which serve as reference points for distance estimates, as well as the localization process itself, affect the localization accuracy. Furthermore, because numerous communications are sent between nodes for localization, energy consumption must be considered. This work presents an energy-aware and accurate localization method. It is based on a combined anchor deployment and energy-aware localization. The proper number and distribution of anchors have been investigated to achieve full network coverage and connectivity based on an efficient and heterogeneous hexagonal deployment. Later, energy-aware localization is performed in three stages: Initialization, signal acquisition, and anchor selection. The initialization step allows the network to be adaptable to sudden changes by establishing anchor connectivity and creating the neighbors' list. Meanwhile, the Received Signal Strength Indicator (RSSI) is used for distance measurements between nodes, with the implementation of a Kalman filter to reduce signal attenuation and noise. Later, the anchor selection is done using fuzzy logic with inference parameters: RSSI, node density, and residual energy. This step ensures that only operable anchors engage in localization, while anchors with inadequate energy sources remain intact to ensure their future availability.:1 Introduction 2 Theoretical background 3 Energy-aware outdoor deployment and localization 4 Proposed anchor deployment method 5 Proposed energy-aware localization method 6 Experimental validation of the proposed localization method / Verschiedene Anwendungen von drahtlosen Sensornetzwerken (WSNs) erfordern eine genaue Lokalisierung von Sensorknoten. Die Anzahl und Standorte der Ankerknoten, die als Referenzpunkte für Entfernungsschätzungen dienen, sowie der Lokalisierungsprozess selbst beeinflussen die Lokalisierungsgenauigkeit. Da für die Lokalisierung zahlreiche Nachrichten zwischen den Knoten gesendet werden, muss außerdem der Energieverbrauch berücksichtigt werden. In dieser Arbeit wird eine energiebewusste und genaue Lokalisierungsmethode vorgestellt. Sie basiert auf einer Kombination aus effizienter Ankerknotennutzung und energiebewusster Lokalisierung. Die richtige Anzahl und Verteilung von Ankern wurde untersucht, um eine vollständige Netzabdeckung und Konnektivität auf der Grundlage einer effizienten und heterogenen hexagonalen Verteilung zu erreichen. Später wird die energiebewusste Lokalisierung in drei Stufen durchgeführt: Initialisierung, Signalerfassung und Ankerauswahl. Der Initialisierungsschritt ermöglicht es dem Netzwerk, sich an plötzliche Veränderungen anzupassen, indem es die Verbindung zu den Ankern und die Liste der Nachbarn erstellt. Zunächst wird der Received Signal Strength Indicator (RSSI) für die Entfernungsmessung zwischen den Knoten verwendet, wobei ein Kalman-Filter implementiert wird, um Signalabschwächung und Rauschen zu reduzieren. Später erfolgt die Ankerauswahl mit Hilfe von Fuzzy-Logik und Inferenzparametern: RSSI, Knotendichte und Restenergie. Dieser Schritt stellt sicher, dass nur funktionsfähige Anker an der Lokalisierung teilnehmen, während Anker mit unzureichenden Energiequellen intakt bleiben, um ihre zukünftige Verfügbarkeit zu gewährleisten.:1 Introduction 2 Theoretical background 3 Energy-aware outdoor deployment and localization 4 Proposed anchor deployment method 5 Proposed energy-aware localization method 6 Experimental validation of the proposed localization method
84

Administrator Perceptions of the Community College Mission in the State of Mississippi and How it may be Influenced by the Addition of Community College Baccalaureate Programs

Grizzell, Scharvin S 07 May 2016 (has links)
For many years, community colleges that chose to offer community college baccalaureate (CCB) programs were looked upon in a negative light (Rice, 2015). However, as the need for specialized baccalaureates within specific fields and job markets have continued to grow (McKee, 2005), CCB programs are becoming more widely accepted throughout the United States. In spite of this paradigm shift, Mississippi is one of the remaining states that have not embraced the idea of CCB programs, in spite of its statistical deficiency in regards to baccalaureate degree holding citizens (Williams, 2010). The focus of this study was to explore the perceptions of community college administrators in Mississippi with regards to the influence of CCB programs to the community college mission of institutions in their state. This study indicates that administrators in Mississippi recognize the benefits of offering CCB programs, but do not want CCB programs to take away from the well-established statewide higher education system through mission creep. Many of the strong position statements received overwhelmingly neutral responses. In contrast, Administrators who chose to give their opinion indicated that they are not familiar with how CCB programs are implemented, and do not believe that Mississippi is ready for CCB programs across the state. However, respondents felt that the community college mission is always evolving, should meet students’ needs, and varies from location to location. The findings also show that administrators are favorable to the piloting of CCB programs at a few (1-2) institutions, even though they believe the programs will take funding away from current programs and do not want community colleges evolving into 4-year institutions. The study also concludes that there is a significant difference between institution size and survey questions #18 and #20. There is also a significant difference between length of time in the community college sector and survey questions #15, #17, and #18.

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