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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.
211

Analyse multi-échelle du comouvement entre les prix du quota carbone, du crédit carbone, et des produits énergétiques / Multi-scale analysis of comovement between the prices of carbon quota, carbon credit, and energetic products

Nsouadi, Clarda 21 June 2016 (has links)
Notre thèse est une contribution à la compréhension de la structure du prix du quota carbone, à l’analyse de sa fluctuation, et aux interactions pouvant exister entre d’une part le système communautaire d’échange de quota d’émission (SCEQE) et le mécanisme pour le développement propre (MDP) et d’autre part entre le marché du quota carbone et ceux du secteur de l’énergie. Pour réaliser cet objectif, nous faisons appel à l’approche temps-fréquence (ondelettes) qui permet d’analyser le comportement local d’un signal, en isolant les composantes relatives aux fréquences de trading des agents. Cette méthode permet de décomposer la variance d’une série chronologique en différentes composantes fréquentielles dont on peut suivre les évolutions au cours du temps. Les horizons temporels de placement sont affectés à chaque bande de fréquences liés à un degré de risque du marché. Les bandes à haute fréquence obtenues par la décomposition en ondelettes renferment l’information relative à la structure de la série chronologique à court terme et non; celle à moyenne et à basse fréquence captent respectivement les structures de la série chronologique à moyen et long terme. Pour concrétiser notre apport nous proposons un développement de notre recherche en 3 chapitres. Le premier présente le marché carbone, sa création, son fonctionnement, et les différents acteurs qui l’animent. La formation du prix du CO2, son évolution et ses facteurs déterminants. Le deuxième développe une analyse multidimensionnelle du comouvement entre le prix du quota (SCEQE) et du crédit carbone (MDP) selon deux hypothèses : la première est l’homogénéité du comportement des agents. La relation de comouvement entre le prix du quota (SCEQE) et du crédit carbone (MDP) suppose que les intervenants sur le marché disposent d’une même stratégie d’investissement. On utilise dans ce cas les outils économétriques standards (Analyse de la Cointégration, de la causalité, modélisation vecteur Autorégressif). Nous mettons en évidence l’existence d’une causalité unidirectionnelle du CER vers l’EUA conforme aux faits observés de l’accélération du mécanisme pour le développement propre (MDP). En effet les industriels portent un grand intérêt sur le MDP, et cela a eu un impact direct sur le prix de l’EUA sur le marché européen du carbone. Nous observons aussi une dynamique d’interconnexion par l’intermédiaire du VAR(1) entre l’EUA et le CER. La deuxième hypothèse est celle de l’hétérogénéité du comportement des agents. Nous étudions la relation de comouvement entre le prix du quota (SCEQE) et celui crédit carbone (MDP) par une analyse multi-échelle dérivée de la théorie des ondelettes. Nous montrons que quels que soient les différents horizons d’investissement retenus (court, moyen et long terme), il existe une relation positive significative entre les deux séries de prix. De plus La causalité dynamique par ondelettes sur chaque paire de bandes de fréquence, confirme notre hypothèse d’une relation instable entre le EUA et le CER. Le troisième chapitre complète le précédent par l’analyse du comouvement multi-échelle entre le prix du quota carbone issu du SCEQE et ceux des marchés énergétiques (pétrole, le Charbon et le Gaz). La cohérence par ondelettes pierre angulaire de cette étude peut être interprétée comme une mesure de corrélation locale calculée de façon non-paramétrique. Cette première tentative de l’analyse multi-échelle de la relation de comouvement entre le marché du CO2, du pétrole, du Gaz et du Charbon fondée sur l’hypothèse d’hétérogénéité des agents montre qu’il est possible aux intervenants sur le marché carbone d’avoir une grande palette de choix de stratégies leurs permettant de mieux se prémunir contre les risques liés aux fortes volatilités du prix du carbone. / The purpose of this thesis is to contribute to the understanding of the carbon price quota structure, the analysis of its fluctuation, and the interactions that may exist between on the one hand the EU system of emission quota exchange (ETS) and the mechanism for clean development (CDM) and on the other hand between carbon quota market and the quota in the energy sector. For this study, we introduced the hypothesis of heterogeneity of agents' behavior on the carbon market where coexist multiple scales of investments.To achieve this, we used a time-frequency approach (wavelets) that can analyze the local behavior of a signal by isolating the components related to the agents’ trading frequency. This method allows variance decomposition of a time series into different frequency components. The time investment horizons are assigned to each frequency band associated with a degree of market risk. High frequency bands obtained by wavelet decomposition contain information pertaining to the short-term time series structure; the medium and the low frequencies respectively capture the structures of the time series in the medium and long term.To complete this project we proposed developing of our research in 3 chapters:The first chapter presents the carbon market, its creation, its operation, and the various actors who animate it. The formation of the CO2 price, its evolution and its determinants were also analyzed during this chapter.The second chapter develops a multi-scale analysis of the co-movement between price of quota (ETS) and carbon credit (CDM). This particular study was based on two assumptions:- The first assumption was the homogeneity of the various agents’ behaviors. The co-movement relationship between the price of quota (ETS) and carbon credit (CDM) assumes that market participants have the same investment strategy especially since all stakeholders agents invest in these markets on the same horizons. This relationship is studied using standard econometric tools such as Analysis of Co-integration of causality and Vector Autoregressive modeling.The main result of this specific part highlights the existence of a unidirectional causality from the ERC to the EUA with an observed acceleration of the mechanism for clean development (CDM). Manufacturers have a strong interest in the CDM which has had a direct impact on the price of EUAs on the European carbon market. We also observed a dynamic interconnection through the VAR (1) between EUA and CER.- The second assumption is the heterogeneity of agents' behavior. We highlighted the relationship of co-movement between price of quota (ETS) and carbon credit (CDM) to a multi-scale analysis derived from wavelet theory. We show that whatever the different investment horizons retained (short, medium and long term), there is a significant positive relationship between the two sets of prices. The more dynamic causal wavelet on each pair of frequency bands detects an unstable relationship between EUA and CER which confirms our working hypothesis.And finally, a third chapter that complements the previous analysis by the co-movement between multi-scale carbon allowance prices resulting from the ETS to those energy markets (oil, coal and gas). Using coherence wavelet, it examined the simultaneous dependence (co-movement) between two price series in time and frequency. It can be interpreted as a local measurement of correlation calculated non-parametrically. Overall, this study is the first attempt at a multi-scale analysis of the co-movement relationship between the CO2 market, Oil, Gas and Coal which is based on the hypothesis of heterogeneity of agents using a template from wavelet algorithm. The model used in this study will allow stakeholders agents on the carbon market to have a great range of choices for their strategies to be able to anticipate wisely because of the high volatility of carbon prices on their different investment horizons.
212

Modelování tržní ceny nemovitosti mnohonásobnou lineární regresí / Market price modelling by real estates with multiple linear regression

Studený, Marek January 2013 (has links)
The main subject of the diploma thesis is a market price modeling by real estates. As a tool for modeling, is used a multiple linear regression. As starting points, are used an econometrical theory and knowledge about real estate valuation. The main goal is to find optimal model for best capture in the time and place.
213

Tunable magnetic vortex dynamics

Ramasubramanian, Lakshmi 31 March 2022 (has links)
Magnetic vortices are fundamental topologically protected magnetic structures which have evolved into a large and intense field of research and hold promise for future technological applications. The fundamental frequency of the magnetic vortex in a disk is directly proportional to the magnitude of the local saturation magnetization and individual sample design resulting in a single vortex precession frequency. Commercial applications like RF oscillators in wireless transmitters and receivers, however, require tuning of the output frequency by external parameters, such as applied fields or spin-polarized currents. It is shown here that the limited tunability of a magnetic vortex in a permalloy disk can be lifted when submitted to local chromium ion implantation by introducing areas in the disk with different saturation magnetization. A static magnetic field is applied to displace the vortex core between these two regions to enable detection of different frequencies corresponding to the respective regions. This realization of multiple resonance frequencies in one and the same magnetic disk is shown experimentally via electrical detection exploiting anisotropic magnetoresistance effects and the results are supported by micromagnetic simulations. In the experiments presented here, the gyrotropic mode is excited at resonance with spin-polarized alternating currents. Systematic investigations (in terms of excitation amplitude, external static field amplitude, angle between static field and current) on the disks without chromium ion implantation clearly indicate that the vortex core is driven by a combination of Oersted field and spin-torque. These measurements also help to identify the linear and non-linear regions of vortex dynamics electrically on single disks. The results shown in this work pave the way for enabling highly tuneable wireless transmitters and receivers based on magnetic vortex structures.
214

Modellierung des nichtlinear-elastischen Verformungsverhaltens von Tragschichten ohne Bindemittel

Numrich, Ralf 12 December 2003 (has links)
Ziel der vorliegenden Dissertation war die Erweiterung der Kenntnisse über das nichtlinear-elastische Spannungs-Verformungsverhalten von Tragschichten ohne Bindemittel (ToB). Ein analytisches Bemessungsverfahren ist aufgrund der schwierigen Modellierbarkeit des Verformungsverhalten der einzelnen Straßenbaustoffe bisher nicht existent. Die Dissertation soll einen Beitrag zur Entwicklung eines solchen Bemessungsverfahrens leisten. Eine Literaturrecherche zum Verformungsverhalten von ToB bildet die Grundlage für die Festlegung der Vorgehensweise. Basis der weiteren Untersuchungen sind Triaxialversuche, die an der Universität Nottingham an verschiedenen Gesteinskörnungen durchgeführt wurden. Mit Hilfe der Shakedown-Theorie konnte belegt werden, dass sich ToB in unterschiedlichen Beanspruchungsbereichen nach verschiedenen Gesetzmäßigkeiten verhalten und dass Modelle zur Beschreibung des Verformungsverhaltens von ToB bereichsweise verschieden formuliert werden müssen. Somit ist es möglich, Gültigkeitsgrenzen für elastische Stoffmodelle zu ermitteln sowie Beanspruchungsgrenzen für ToB festzulegen. Mit ausgewählten Stoffmodellen erfolgten Beanspruchungsberechnungen nach der Finite-Elemente Methode (FEM). Die beste Annäherung zwischen Messwerten und Rechenergebnissen ergibt sich bei Anwendung des DRESDNER Modells. Berechnungen für Befestigungen nach den RStO 01 haben gezeigt, dass die Beanspruchungen auf den ToB bei Anwendung des DRESDNER Modells stark von denen bei Anwendung linearer Elastizität abweichen können. Durch unterschiedliche Überbauungsdicken der ToB besitzen diese einen verschieden hohen Anteil am Tragverhalten der Befestigung. Abschließend wird eine Methode zur Ermittlung von Sicherheitsniveaus vorgestellt. Bei Kenntnis der entsprechenden Schichtparameter lassen sich die Beanspruchungen jeder beliebigen Bauweise mit denen von Bauweisen nach RStO vergleichen. Als Ergebnis kann festgehalten werden, dass das Sicherheitsniveau einer bestimmten Bauweise nach RStO genauso groß ist, wie eine Befestigung mit einer dünneren Asphalttragschicht, dafür jedoch einer steiferen ToB. / The aim of this thesis was the extension of the knowledge about the resilient stress-deformation behaviour of unbound granular materials (UGM). Due to difficulties in modelling the behaviour of the single materials an analytical design method does not exist at present. Therefore this thesis makes a contribution for developing such a design method. A study of international publications about the current knowledge of the stress-deformation behaviour of UGM and repeated load triaxial tests, which have been performed at Nottingham University, were the base for all further investigations. With the shakedown concept it could be shown that materials behave in a different manner depending on the applied stress level and that material laws for describing the resilient deformation behaviour of UGM have to be formulated separately for different stress ranges. Within this thesis a method is introduced which helps to find boarders for the applicability of different material laws and limiting stress lines where below the lines stable behaviour and admissible deformations for the material are expected. Applying selected material laws finite element calculations have been performed. Comparing calculation results with measurement results it can be shown that the Dresden model offers the best approach. Calculations for pavement constructions applying the Dresden model have resulted that the vertical stresses differ very much in comparison with elastic behaviour for the UGM. It can be concluded that the thickness of the covering bounded layers have an effect to the contribution of the unbound granular layers at the complete deformation behaviour of the pavement construction. Finishing a method is introduced to determine the safety levels of pavement constructions. It seems to be possible to compare the stress-strain levels of any pavement construction with those from the german standard RStO 01. Existing functions could be modified to determine safety coefficients, i. e. ratios between admissible and existing numbers of load cycles. It can be concluded that there are the same safety levels for different pavement constructions ? a thinner asphalt layer can be compensated with a stiffer UGM.
215

Effect of the voltage dependency of the device-level gate-source capacitance in the linearity of a common-gate amplifier

Eduardo A. Garcia (5929682) 19 July 2022 (has links)
<p>Most work on amplifier linearity has focused on the transconductance (gm) linearity, but there is increasing evidence that the voltage-dependence of the gate-source capacitance (Cgs) plays an important role in the linearity of emerging devices. This work addresses the capacitance contribution by incorporating the nonlinearities attributed to the voltage dependency of Cgs of a general FET on a circuit-level Cg amplifier model.</p> <p>An amplifier model including a voltage-dependent Cgs, and a voltage-dependent gm is studied using harmonic analysis and Volterra series. A closed form expression for the  third-order intercept point (IP3) of the amplifier, which depends on the nonlinear coefficients of Cgs, is obtained. A simple design rule, and a formula for the reduction of the IP3 due to the voltage-dependent Cgs are also presented. </p> <p>As application examples, the linearity of an amplifier based on a specific device is analyzed for two cases by extracting the nonlinear circuit parameters of the device. First for an analytic model of a bulk mosfet. Second for a one-dimensional, ballistic, coaxially gated Si nanowire. For low frequencies of design, the distortion introduced by gm is predominant, but for high frequencies it is obscured by the distortion coming from Cgs.</p> <p>We conclude that taking into account the voltage-dependence of Cgs is crucial when predicting the linearity behavior of a Cg amplifier, either designed for high-frequency operation, or based on a device operating near the quantum capacitance limit. </p>
216

Studies of sound generation and propagation in flow ducts

Ducret, Fabrice January 2006 (has links)
This thesis contains three papers investigating problems of interest for noise control in ducts. The first part of this thesis treats the sound propagation in rectangular ducts with flexible walls. Various experimental techniques are performed to measure the internal sound propagation and radiation to the surrounding. An analytical model is derived to calculate the coupled propagation wavenumber and radiated sound power. The two-port formalism is used. The second part starts with the sound propagation in open ended circular straight pipe with airflow (a tailpipe). Various aspects such as: acoustic damping, reflection and transmission at the open termination are investigated. Sound absorption due to vorticity shed at the opening is also treated. The geometry of the opening is then modified (oblique cuts, diffusers) and comparisons with the reference straight pipe is made for the sound transmission and flow induced noise generation. The effect of an upstream bend close to the opening is also investigated. In the third part the acoustic impedance of perforated plates are investigated. In particular the application to small perforation ratios ( ≈ 1% ) and holes or slits with apertures of sub-millimetre size, so called micro-perforated plates, are of interest. Linear and non-linear regimes are investigated. A model is derived to calculate the linear acoustic impedance of perforated elements. / QC 20101111
217

Do gesto à linguagem matricial. Estudo das alterações morfológicas do desenho da letra no espaço virtual

DE MAGALHAES LEMOS, JOAO FERNANDO 07 March 2016 (has links)
[EN] From the gesture to the matrix language. Study of the handwriting morphological drawing changes in the virtual space. Writing transformed in an indelible way the human history and changed the relations between the individual and the social memory. With writing the words are closed in a visual field and the knowledge acquisition does not occur through the memory but through the written text, which relativizes the role of the subject's memory. Digital media call into question the concept of book and allowed the creation of new textual characteristics. The linear structure of textual information gives place to a fragmented structure, expressed in the visual/ verbal dynamism of the various interfaces that interact with the individual, bringing to the forefront the relationship between speech and writing. Digital technologies have transformed the communicative practices and redefined the visual relationships established between thought and space, particularly in the world of printing and textual visualization. The use of hypertext and hypermedia for presentation of information, generated major changes in reading and writing and put the language - spoken, written and iconographic - in a context much richer and broader than in the printed text, enhancing the articulated significance (verbality), the pictorial sense (plasticity), the acoustic sense (sonority) and kinetic sense (movement) of the word. The new virtual media altered the writing morphology as well as the nature of the messages leading to a change in the written message nature and fostering the emergence of new typographic paradigms. In the context of this investigation, is approached the typographical form and its relationship with the support and the instrument that records it, analysing hand movement which formalizes a letter. Secondly, it analyses the shape of the letter in two-dimensional space, its organization and distribution, responsible for assigning meaning to the messages and ideas, promoting the entire text of the interaction field and typographical form with space. In the third phase, it deals with the simulation letterpress movement evolving in space and time, considered as an idea that lends identity and character to a world that is not already the printed plan. This sustained research in historical identification, formal and conceptual of typographic forms and analysis of cultural, social and technological factors that promoted morphological changes evidenced in typographic design, was based on theoretical reflections that helped analyse the resources and expressive strategies to limit the syntax and semantics of the typographic form in the digital context. >< / [ES] Del gesto al lenguaje matricial. Estudio de las alteraciones morfológicas del diseño de la letra en el espacio virtual La escritura transformó de forma indeleble la historia humana, y con ella, cambiaron las relaciones entre el individuo y la memoria social. Con la escritura, las palabras se encierran en un campo visual y la adquisición del conocimiento no se produce tanto por la intermediación de la memoria, sino por el texto escrito que relativiza el papel de la memoria del individuo. Los medios de comunicación digitales han cuestionado el concepto de libro y han permitido la creación de nuevas características textuales. La estructuración lineal de la información textual da lugar a una estructuración fragmentada, expresada en el dinamismo visual/ verbal de las diversas interfaces que interactúan con el individuo, poniendo en primer plano la relación entre el habla y la escritura. Las tecnologías digitales han transformado las prácticas comunicativas y han redefinido las relaciones visuales que se establecen entre el pensamiento y el espacio, particularmente en el universo de la impresión y de la visualización textual. El uso del hipertexto y del hipermedia para la presentación de la información ha generado grandes cambios en la lectura y en la escritura y ha colocado la lengua - hablada, escrita e iconográfica - en un contexto mucho más rico y amplio que en el texto impreso, potenciando la significación articulada (verbalización), el sentido pictórico (plasticidad), el sentido acústico (sonoridad) y el sentido cinético (movimiento) de la palabra. Los nuevos medios virtuales han modificado la morfología de la escritura así como la naturaleza de los mensajes, dando origen a un cambio en la naturaleza del mensaje escrito y promoviendo el surgimiento de nuevos paradigmas tipográficos. En el contexto de esta investigación, se aborda la forma tipográfica y su relación con el soporte y con el instrumento que la registra, analizando el movimiento de la mano que formaliza una letra. En segundo lugar, se analiza la forma de la letra en el espacio bidimensional, su organización y distribución, responsable por dar sentido a los mensajes y a las ideas, promoviendo todo el campo de interacción del texto y de la forma tipográfica con el espacio. En tercer lugar, se trata la simulación del movimiento de la tipografía evolucionando en el espacio y en el tiempo, afrontada como idea que concede identidad y carácter a un mundo que ya no es, el del plano impreso. Esta investigación apoyada en la identificación histórica, formal y conceptual de las formas tipográficas y en el análisis de los factores culturales, sociales y tecnológicos a los que dieron lugar los cambios morfológicos evidenciados en el diseño tipográfico, se fundamentó en reflexiones teóricas que han permitido analizar los recursos y las estrategias expresivas para circunscribir la sintaxis y la semántica de la forma tipográfica en el contexto digital. >< / [CA] Del gest al llenguatge matricial. Estudi de les alteracions morfològiques del disseny de la lletra en l'espai virtual. L'escriptura va transformar de forma indeleble la història humana, i amb ella, van canviar les relacions entre l'individu i la memòria social. Amb l'escriptura, les paraules es tanquen en un camp visual i l'adquisició del coneixement no es produeix tant per la intermediació de la memòria, sinó pel text escrit que relativitza el paper de la memòria de l'individu. Els mitjans de comunicació digitals han qüestionat el concepte de llibre i han permès la creació de noves característiques textuals. L'estructuració lineal de la informació textual dóna lloc a una estructuració fragmentada, expressada en el dinamisme visual/ verbal de les diverses interfícies que interactuen amb l'individu, posant en primer plànol la relació entre la parla i l'escriptura. Les tecnologies digitals han transformat les pràctiques comunicatives i han redefinit les relacions visuals que s'estableixen entre el pensament i l'espai, particularment en l'univers de la impressió i de la visualització textual. L'ús de l'hipertext i del 'hipermedia' per a la presentació de la informació ha generat grans canvis en la lectura i en l'escriptura i ha col·locat la llengua - parlada, escrita i iconogràfica - en un context molt més ric i ampli que en el text imprès, potenciant la significació articulada (verbalització), el sentit pictòric (plasticitat), el sentit acústic (sonoritat) i el sentit cinètic (moviment) de la paraula. Els nous mitjans virtuals han modificat la morfologia de l'escriptura així com la naturalesa dels missatges, donant origen a un canvi en la naturalesa del missatge escrit i promovent el sorgiment de nous paradigmes tipogràfics. En el context d'aquesta recerca, s'aborda la forma tipogràfica i la seua relació amb el suport i amb l'instrument que la registra, analitzant el moviment de la mà que formalitza una lletra. En segon lloc, s'analitza la forma de la lletra en l'espai bidimensional, la seua organització i distribució, responsable per donar sentit als missatges i a les idees, promovent tot el camp d'interacció del text i de la forma tipogràfica amb l'espai. En tercer lloc, es tracta la simulació del moviment de la tipografia evolucionant en l'espai i en el temps, afrontada com a idea que concedeix identitat i caràcter a un món que ja no és, el del plànol imprès. Aquesta recerca recolzada en la identificació històrica, formal i conceptual de les formes tipogràfiques i en l'anàlisi dels factors culturals, socials i tecnològics als quals van donar lloc els canvis morfològics evidenciats en el disseny tipogràfic, es va fonamentar en reflexions teòriques que han permès analitzar els recursos i les estratègies expressives per a circumscriure la sintaxi i la semàntica de la forma tipogràfica en el context digital. >< / De Magalhaes Lemos, JF. (2016). Do gesto à linguagem matricial. Estudo das alterações morfológicas do desenho da letra no espaço virtual [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/61480
218

High Performance RF and Basdband Analog-to-Digital Interface for Multi-standard/Wideband Applications

Zhang, Heng 2010 December 1900 (has links)
The prevalence of wireless standards and the introduction of dynamic standards/applications, such as software-defined radio, necessitate the next generation wireless devices that integrate multiple standards in a single chip-set to support a variety of services. To reduce the cost and area of such multi-standard handheld devices, reconfigurability is desirable, and the hardware should be shared/reused as much as possible. This research proposes several novel circuit topologies that can meet various specifications with minimum cost, which are suited for multi-standard applications. This doctoral study has two separate contributions: 1. The low noise amplifier (LNA) for the RF front-end; and 2. The analog-to-digital converter (ADC). The first part of this dissertation focuses on LNA noise reduction and linearization techniques where two novel LNAs are designed, taped out, and measured. The first LNA, implemented in TSMC (Taiwan Semiconductor Manufacturing Company) 0.35Cm CMOS (Complementary metal-oxide-semiconductor) process, strategically combined an inductor connected at the gate of the cascode transistor and the capacitive cross-coupling to reduce the noise and nonlinearity contributions of the cascode transistors. The proposed technique reduces LNA NF by 0.35 dB at 2.2 GHz and increases its IIP3 and voltage gain by 2.35 dBm and 2dB respectively, without a compromise on power consumption. The second LNA, implemented in UMC (United Microelectronics Corporation) 0.13Cm CMOS process, features a practical linearization technique for high-frequency wideband applications using an active nonlinear resistor, which obtains a robust linearity improvement over process and temperature variations. The proposed linearization method is experimentally demonstrated to improve the IIP3 by 3.5 to 9 dB over a 2.5–10 GHz frequency range. A comparison of measurement results with the prior published state-of-art Ultra-Wideband (UWB) LNAs shows that the proposed linearized UWB LNA achieves excellent linearity with much less power than previously published works. The second part of this dissertation developed a reconfigurable ADC for multistandard receiver and video processors. Typical ADCs are power optimized for only one operating speed, while a reconfigurable ADC can scale its power at different speeds, enabling minimal power consumption over a broad range of sampling rates. A novel ADC architecture is proposed for programming the sampling rate with constant biasing current and single clock. The ADC was designed and fabricated using UMC 90nm CMOS process and featured good power scalability and simplified system design. The programmable speed range covers all the video formats and most of the wireless communication standards, while achieving comparable Figure-of-Merit with customized ADCs at each performance node. Since bias current is kept constant, the reconfigurable ADC is more robust and reliable than the previous published works.
219

Analysis of Accuracy for Engine and Gearbox Sensors

Dogantimur, Erkan, Johnsson, Daniel January 2019 (has links)
This thesis provides a standardized method to measure accuracy for engine and gearbox sensors. Accuracy is defined by ISO 5725, which states that trueness and precision need to be known to provide a metric for accuracy. However, obtaining and processing the data required for this is not straight forward. In this thesis, a method is presented that consists of two main parts: data acquisition and data analysis. The data acquisition part shows how to connect all of the equipment used and how to sample and store all the raw data from the sensors. The data analysis part shows how to process that raw data into statistical data, such as trueness, repeatability and reproducibility for the sensors. Once repeatability and reproducibility are known, the total precision can be determined. Accuracy can then be obtained by using information from trueness and precision. Besides, this thesis shows that measurement error can be separated into error caused by the sensors and error caused by the measurand. This is useful information, because it can be used to assess which type of error is the greatest, whether or not it can be compensated for, and if it is economically viable to compensate for such error.  The results are then shown, where it is possible to gain information about the sensors’ performance from various graphs. Between Hall and inductive sensors, there were no superior winner, since they both have their strengths and weaknesses. The thesis ends by making recommendations on how to compensate for some of the errors, and how to improve upon the method to make it more automatic in the future.
220

Optimising the usability of content rich e-learning material: an eye tracking experiment

Mpofu, Bongeka 11 1900 (has links)
This research was aimed at the optimisation of the usability of content-rich computer and mobile based e-learning material. The goal was to preserve the advantages of paper based material in designing optimised modules that were mobile and computer-based, but at the same time avoiding the pitfalls of converting traditional paper based learning material for use on screen. A mobile eye tracker was used to analyse how students studied similar course content on paper, and on mobile device. Screen based eye tracking was also used to analyse how participants studied corresponding content on a desktop screen. Eye movements which were recorded by an eye tracker revealed the sequences of fixations and saccades on the text that was read by each participant. By analysing and comparing the eye gaze patterns of students reading the same content on three different delivery platforms, the differences between these platforms were identified in terms of their delivery of content rich, text based study material. The results showed that more students read online content on a computer screen than on mobile devices. The inferential analysis revealed that the differences in reading duration, comprehension, linearity and fixation count on the three platforms were insignificant. There were significant differences in saccade length. This analysis was used to identify strong aspects of the respective platforms and consequently derive guidelines for using these aspects optimally to design content rich material for delivery on computer screen and mobile device. The limitations of each platform were revealed and guidelines for avoiding these were derived / Computing / M.A. (Computing)

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