abstract: A wideband hybrid envelope tracking modulator utilizing a hysteretic-controlled three-level switching converter and a slew-rate enhanced linear amplifierer is presented. In addition to smaller ripple and lower losses of three-level switching converters, employing the proposed hysteresis control loop results in a higher speed loop and wider bandwidth converter, enabling over 80MHz of switching frequency. A concurrent sensor circuit monitors and regulates the flying capacitor voltage VCF and eliminates conventional required calibration loop to control it. The hysteretic-controlled three-level switching converter provides a high percentage of power amplifier supply load current with lower ripple, reducing the linear amplifier high-frequency current and ripple cancellation current, improving the overall system efficiency. A slew-rate enhancement (SRE) circuit is employed in the linear amplifier resulting in slew-rate of over 307V/us and bandwidth of over 275MHz for the linear amplifier. The slew-rate enhancement circuit provides a parallel auxiliary current path directly to the gate of the class-AB output stage transistors, speeding-up the charging or discharging of out- put without modifying the operating point of the remaining linear amplifier, while maintaining the quiescent current of the class-AB stage. The supply modulator is fabricated in 65nm CMOS process. The measurement results show the tracking of LTE-40MHz envelope with 93% peak efficiency at 1W output power, while the SRE is disabled. Enabling the SRE it can track LTE-80MHz envelope with peak efficiency of 91%. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

abstract: Power management integrated circuit (PMIC) design is a key module in almost all electronics around us such as Phones, Tablets, Computers, Laptop, Electric vehicles, etc. The on-chip loads such as microprocessors cores, memories, Analog/RF, etc. requires multiple supply voltage domains. Providing these supply voltages from off-chip voltage regulators will increase the overall system cost and limits the performance due to the board and package parasitics. Therefore, an on-chip fully integrated voltage regulator (FIVR) is required. The dissertation presents a topology for a fully integrated power stage in a DC-DC buck converter achieving a high-power density and a time-domain hysteresis based highly integrated buck converter. A multi-phase time-domain comparator is proposed in this work for implementing the hysteresis control, thereby achieving a process scaling friendly highly digital design. A higher-order LC notch filter along with a flying capacitor which couples the input and output voltage ripple is implemented. The power stage operates at 500 MHz and can deliver a maximum power of 1.0 W and load current of 1.67 A, while occupying 1.21 mm2 active die area. Thus achieving a power density of 0.867 W/mm2 and current density of 1.377 A/mm2. The peak efficiency obtained is 71% at 780 mA of load current. The power stage with the additional off-chip LC is utilized to design a highly integrated current mode hysteretic buck converter operating at 180 MHz. It achieves 20 ns of settling and 2-5 ns of rise/fall time for reference tracking. The second part of the dissertation discusses an integrated low voltage switched-capacitor based power sensor, to measure the output power of a DC-DC boost converter. This approach results in a lower complexity, area, power consumption, and a lower component count for the overall PV MPPT system. Designed in a 180 nm CMOS process, the circuit can operate with a supply voltage of 1.8 V. It achieves a power sense accuracy of 7.6%, occupies a die area of 0.0519 mm2, and consumes 0.748 mW of power. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

Capillarity is often exploited in self-cleaning, drag reducing and fluid absorption/storage (sanitary products) purposes just to name a few. Formulating the underlying physics of capillarity helps future design and development of optimized structures. This work reports on developing computational models to quantify the capillary pressure and capillary forces on the fibrous surfaces. To this end, the current study utilizes a novel mass-spring-damper approach to incorporate the mechanical properties of the fibers in generating virtual fibrous structures that can best represent fibrous membranes. Such virtual fibrous structures are then subjected to a pressure estimation model, developed for the first time in this work, to estimate the liquid entry pressure (LEP) for a hydrophobic fibrous membrane. As for accurate prediction (and not just estimation) of the capillary pressure, this work also presents an energy minimization method, implemented in the Surface Evolver code, for tracking the air–water interface intrusion in a hydrophobic fibrous membrane comprised of orthogonally oriented fibers. This novel interface tracking algorithm is used to investigate the effects of the membrane’s microstructure and wetting properties on its resistance to water intrusion (i.e., LEP). The simulation method developed in this work is computationally affordable and it is accurate in its predictions of the air–water interface shape and position inside the membrane as a function of pressure. Application of the simulation method in studying effects of fiber diameter or contact angle heterogeneity on water intrusion pressure is reported for demonstration purposes. Capillary forces between fibrous surfaces are also studied experimentally and numerically via the liquid bridge between two parallel plates coated with electrospun fibers. In the experiment, a droplet was placed on one of the polystyrene- or polyurethane-coated plates and then compressed, stretched, or sheared using the other plate and the force was measured using a sensitive scale. In the simulation, the liquid bridge was mathematically defined for the Surface Evolver finite element code to predict its 3-D shape and resistance to normal and shearing forces, respectively, in presence of the contact angle hysteresis effect. Despite the inherent non-uniformity of the fibrous surfaces used in the experiments and the simplifying assumptions considered for the simulations, reasonable agreement was observed between the experiments and simulations. Results reveal that both normal and shear force on the plates increase by increasing the liquid volume, or decreasing the spacing between the plates.

The thesis of Dissent after 1989. The use of Pierre Bourdieu's theory of habitus change on the example of selected post-dissent organizations deals with the topic of dissent after 1989 and his subsequent life and influence in the Czech society after 1989. The theme of the post-dissent is conceived through a qualitative the research of organizations whose activity is based on the legacy of dissent or refers to its activities. With the help of the research design of instrumental case studies, the following organizations are organized: Charter 77 Foundation, Václav Havel Library, Babylon, Libri prohibiti. The monitored themes are the development of the organization's relationship towards disentanglement, the dissent reflection in the current activities of the organization, and how the organization communicates these themes towards the public. The theoretical part of the thesis outlines the issues of dissent and post-dissent, which are further embedded in the post-communist transition and presentation of the methodology of qualitative studies. In the second part of the case studies of the above mentioned organizations. I outline their focus and development towards dissent. The last part is an analysis of this development through the theoretical concepts of habitus change of Pierre Bourdieu. The aim is...

The City of Cape Town is the most congested city in South Africa, with Johannesburg coming in second. Capetonians are spending 75% more time in traffic because of the congestion during peak hours, thus reducing time spent on leisure and other activities. Due to population growth, increasing car ownership and declining capacity of rail infrastructure, Cape Town's road infrastructure will continue to be under severe pressure if the status quo is maintained. Research shows that congestion levels in urban areas are key factors in determining the effectiveness and productivity of the transport system. Traffic congestion poses a threat to the economy and the environment. Increasing corridors' capacity by increasing the number of lanes does not necessarily solve the problem. Effective urban traffic management and efficient utilization of existing infrastructure are critical in creating sustainable solutions to congestion problems. To achieve this, it is important that appropriate urban-scale models and monitoring strategies are put in place. Effective traffic management and monitoring strategies require accurate characterization of the traffic state of an urban-scale network. Several approaches, including kinetic wave theory and cell transmission models or macroscopic traffic simulation models, have been proposed and developed to describe the traffic state of an urban-scale network. However, these approaches are limited and require significant amounts of computational time and effort. The application of macroscopic fundamental diagram (herein referred to as MFD) to characterize the state of an urban-scale network has thus far proven to be more effective than other approaches. MFD represents the state of urban traffic by defining the traffic throughput of an area at given traffic densities. It describes the characteristics and dynamics of urban-scale traffic conditions, allowing for improved and sustainable urban scale traffic management and monitoring strategies. Against this backdrop, the existence of MFD for the City of Cape Town (CoCT) urbanscale network is yet to be established and the implications yet to be understood, as in other parts of the world. The main aim of this research was, therefore, to empirically estimate the macroscopic fundamental diagram for the CoCT's freeway network and analyse its observed features. To achieve this, observed data of 5 minutes periods for the month of May 2019 was used to estimate the MFD. The results confirmed that when the chaotic scatter-plots of flow and density from individual fixed loop detectors were aggregated the scatter nearly disappeared and points grouped neatly to form a clearly defined free-flow state, critical state and the formation of hysteresis loops past the critical density corresponding with the network observed maximum flow. Further analysis of the MFDs showed that a single hysteresis loop always forms past the critical density during the evening peak in a weekday MFD. However, it was inconclusive during the morning peak period in weekday MFDs. Lastly, an explicit hysteresis loop seldom appears in a Saturday MFD when the peak of traffic demand is lower than on weekdays. In order to understand the dynamics of the congestion spread, the freeway network was partitioned into penetrating highways network and the ring highway network. The results showed that the maximum flows observed for the two sub-networks were significantly different (943 veh/hr/lane for the penetrating highways network and 1539 veh/hr/lane for the ring highway network). The penetrating highways network's MFD indicated the presence of congestion in the network whereas the ring highway network indicated only the free-flow state (no indication of congestion) during peak periods. The congestion seen on the penetrating highways network was found not to be sufficiently spread on those highways. On the 24th May, congestion on the penetrating highway network was observed during both the morning and evening peak periods, whereas on the 31st May congestion was observed mainly during the evening peak period, with hysteresis-like shape. These observations confirmed that congestion during peak periods is not homogenously spread across the entire network, certain areas are more congested than others, hence the observed formation of hysteresis loops and slight scatters. Lastly, the hysteresis loops observed in the penetrating highways network's MFD was further characterized in terms of their shape and size. First, the results showed that the slight scatter and hysteresis patterns observed in penetrating highways network MFD's vary in size and shape across different days. The shapes of the hysteresis loops observed during both the morning and evening peak periods, were type H2 hysteresis loops, signifying a stable recovery of the network with the average network flow remaining unchanged as average network density decreases during the recovery. Characterization of the size of the observed hysteresis loops showed that the drop of the hysteresis (an indicator of network level of instability during recovery phase) was smaller, signifying a more stable network traffic and homogenous distribution of congestion during the recovery phase.

This thesis highlights generic aspects of contact angle hysteresis and stick-slip motion,encountered in most practical wetting situations.First, we study the scaling relation between the heterogeneity strength and the amplitudeof the contact angle hysteresis it induces in the model configuration of a chemicallyheterogeneous microchannel. A key parameter which determines the qualitativefeatures is the heterogeneity wavelength. In particular, we identify a near-thresholdbehavior where the quadratic scaling between the heterogeneity amplitude and the resultinghysteresis, already known for a dilute system of wetting defects, is explainedby the closeness to the threshold, and a macroscopic limit without observable stick-slipwhere this scaling is linear.In the second part, we adapt the description to the configuration of a meniscusaround a wavy fibre. This adaptation brings the generic results of the first part in thereach of experiments. A comparison with experiments is achieved at the level of theindividual topography-induced jumps.In the third part, we expand the formulation to treat the quasi-steady interface shapecontact line dynamics and study how the the presence of stick-slip motion at the observableor unobservable scale modifies the scaling relation between the contact linevelocity and contact angle. We recover the known result that the scaling exponent dependson the nature of the externally controlled parameter, identify the causes of thisdependency in the corresponding static limits, and predict the disappearance of this dependencyabove a critical velocity which decreases with the heterogeneity wavelength.Finally, we show trough examples how the modelling framework which permitscapturing contact angle hysteresis and stick-slip motion in a minimalistic way can beadopted to treat configurations with a finite amount of contact points, or the 3D problemof a drop with a deformed contact line. We discuss the arising configuration-specificeffects, also in configurations of biomimetic interest. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Les matériaux piézoélectriques et ferroélectriques présentent un comportementélectromécanique couplé. Cette particularité leur a permis d’être utilisés dans de nombreusesapplications telles que les applications de capteur, actionneur, transformateur et récupérateurd’énergie. En outre, en raison de leur comportement non linéaire et dissipatif, les matériauxferroélectriques sont de plus en plus utilisés dans le domaine de l’électronique en tant quecapacité accordable, mémoire non volatile, oscillateur et filtre. La performance et la fiabilitéde ces systèmes dépendent directement des propriétés ferroélectriques et piézoélectriques dumatériau, qui nécessite par conséquent d’être caractérisé. Les propriétés piézoélectriques,ferroélectriques, ferroélastiques et diélectriques des matériaux ferroélectriques ont été le sujetde nombreuses études. Pourtant, les conditions d’essai restent difficiles à maîtriser car lespropriétés thermiques, mécaniques et électriques de ces matériaux sont fortement couplées.Dans cette thèse, un dispositif de mesure de champ de déformation a été conçu pourcaractériser le comportement piézoélectrique et ferroélectrique des céramiquesferroélectriques. Ce dispositif utilise un banc optique ainsi qu’un algorithme de Corrélationd’Images Numériques (CIN) 2D appelé CorreliRT3. Cet algorithme est basé sur une approcheglobale et réduit les erreurs de mesure de déplacement en s’appuyant sur les équationsd’équilibre de la mécanique des solides. Grâce au banc de caractérisation par CIN, il estmontré que les déformations piézoélectriques et ferroélectriques peuvent être mesurées avecune incertitude d’environ 10-5. Cette incertitude est atteinte aussi bien pour des sollicitationssimples que couplées (champ électrique et/ou contrainte mécanique). Il est aussi montré quele banc expérimental permet de vérifier les conditions d’essai en caractérisant l’hétérogénéitédes déformations lors d’un essai matériau.Dans les deux derniers chapitres, un matériau ferroélectrique est caractérisé souschamp électrique et sous contrainte mécanique. Le comportement du matériau est présenté etdiscuté dans les différentes configurations de chargement. Les propriétés matériau, telles queles coefficients piézoélectriques (d33, d31), sont extraites et étudiées en fonction du champélectrique et de la contrainte. Les résultats montrent que la CIN est capable de mesurer etcaractériser le comportement et les propriétés des matériaux ferroélectriques etpiézoélectriques. L’avantage de la CIN étant que, contrairement aux méthodes de mesureclassiques, celle-ci ne perturbe pas les conditions d’essai (mesure sans contact) et permette dedétecter la présence d’erreurs systématiques. / Piezoelectric and ferroelectric materials exhibit a coupled electromechanicalbehaviour. This property allows a use in various kinds of applications such as sensors,actuators, harvesting devices or converters. In addition, due to their non-linear and dissipativebehaviour, ferroelectric materials are increasingly used in electronic applications such astunable capacitors, non-volatile memory, oscillators and filters. The performance andreliability of such devices depend on the material electromechanical properties, whichconsequently need to be characterised. In the past decades, such characterisation was largelydeveloped and the piezoelectric, ferroelectric, ferroelastic and dielectric properties offerroelectrics were the subject of numerous studies. Yet the test conditions are difficult tocontrol due to the strong interplay between thermal, mechanical and dielectric properties.In this work, a full-field measurement apparatus has been designed to characterise thepiezoelectric and ferroelectric strain behaviour of ferroelectric ceramics. This apparatus usesan optical setup and a 2D Digital Image Correlation (DIC) algorithm named CorreliRT3. Thealgorithm is based on a global approach and reduces the displacement field errors using thebalance equations of solid mechanics. It is shown that piezoelectric and ferroelectric strainscan be measured with an uncertainty around 10-5 by using the developed setup. Thisuncertainty is reached under uncoupled or coupled loading (electric field and/or stress). It isalso shown that the experimental setup can control the test conditions by characterising thestrain heterogeneity during the test.In the two last chapters, a ferroelectric material is characterised under electric field andstress. The material behaviour is presented and discussed in the different loadingconfigurations. Material properties, such as the longitudinal and transverse piezoelectriccoefficients (d33, d31) are extracted and analysed as a function of the electric field and stress.The results show that the DIC technique is able to measure and characterise the behaviour andthe properties of ferroelectric and piezoelectric materials. The main benefits of this techniqueis that, contrary to classical measurement techniques, the measurement does not alter the testconditions. Moreover, DIC is able to detect test anomalies such as strain heterogeneities

Replacing electronic components with molecule-sized analogs or hybrids is often seen as a promising alternative to further miniaturization of conventional electronics in the effort to achieve functional nanoscale circuit elements. In this thesis, electronic transport through self-assembled networks with tunable thiolated (alkane(di)thiol and benzenedithiol) molecule-to-colloidal gold (Au) nanoparticle ratios (1:5–50:1) is studied using a combination of broad area and scanning probe microscope-based measurements. The electronic transport paths through the network can be altered by adjusting the (di)thiol molecule–gold nanoparticle ratio and/or type of molecules in the network. Resistance can be controllably tuned by several orders of magnitude (~105 to 1011 ohms for the Au-thiolated structures studied). Two-terminal current–voltage (I-V) measurements of the Au-thiolated networks display linear behavior at low bias. High bias measurements in case of benzenedithiol networks show nonlinear negative differential resistance (NDR) and hysteresis behavior for different benzenedithiol concentrations, which can be attributed to a combination of field-assisted tunneling and charge trapping occurring in the nanoscale networks. Circuit simulations that account for different network morphologies, tunable via molecule-to-nanoparticle ratio, and defects show good agreement with the experiment and provide a guide to engineer network properties using different molecules. In addition, electronic transport properties of nanoscale networks, which are composed of Au metal clusters interconnected with thiolated molecules (benzene/alkanedithiol) and connected in linear chains and branched extended networks, are examined via first-principles density functional theory-based simulations. Calculated I-V characteristics of the metal-molecular networks exhibited nonlinearities and rectification with NDR peaks that became more pronounced with increasing chain length. The transmission spectra of the linear chains and branched networks showed an increase in the number and width of transmission peaks near the Fermi energy, as the structures were extended, indicating enhanced transmission. Peak-to-valley current NDR ratios as large as ~ 500 and rectification ratios of ~ 10 (0.25 V) were shown for linear and branched circuit elements, respectively, illustrating how charge transport through molecular-scale devices could be controlled with precision by modifying the structure and geometry of molecule-nanoparticle networks. These experimental and simulation results are utilized to propose molecular-scale circuits in applications such as memory, switching, and hardware security. The metal nanoparticle molecular electronic networks presented in this thesis provide an avenue for engineering electronics at the molecular level. / Graduate

The diploma thesis deals with determination of modal parameters for machine tool manage-ment. Experimental modal analysis is performed and a new method for determining the damping and stiffness of the machine tool guidance is proposed. A mathematical model for the calculation of signals using state equations was created and the damping stiffness was determined using hysteresis curves.

The aim of this study was to understand how Swedish journalists balance social media use with traditional journalistic ideals and journalism ethics in a context of increasing digitalization, in light of a number of journalistic profiles being criticized for sharing inappropriate content on their social media accounts. The study is rooted in Bourdieu’s field theory and the research questions pertained to how journalists, occupying different positions in the journalistic field, used and viewed social media in relation to journalistic ideals and -ethics as well as their news organizations’ social media policies. In order to answer the research questions, 12 in-depth interviews were conducted with Swedish journalists from five national publications. In the analysis, Bourdieu’s concepts of field, capital, habitus, but also practical sense and hysteresis were used to analytically describe the participants’ social media use.   The findings indicated that the participants used social media frequently in their work, which could be analyzed as part of the field’s doxa. Yet, they used different strategies of risk management on their own social media accounts in order to protect themselves and their well-being as well as not risking going against journalistic ideals and their organization’s social media policies, e.g., by avoiding posting own content, separating professional and personal content on different platforms and not being private on social media. Due to successful risk management and practical sense in regard to social media use, the participants experienced hysteresis to a very low extent. Finally, the analysis concluded with a discussion on potential implications the study has on the field’s autonomy, in terms of increased audience interaction and strength of journalistic ideals, which was seen as both weakening and potentially strengthening autonomy.  Key words: Journalistic field, Bourdieu, field theory, social media, digitalization, journalistic ideals, Sweden, hysteresis, autonomy