The apoptosis and dysfunction of vascular smooth muscle cells in the human descending thoracic aorta is often associated with cardiovascular diseases like aortic dissection and aneurysms. Knowledge of the mechanical effects of contractile smooth muscle cells plays a crucial role in the understanding these potentially lethal conditions. Located in the medial layer, vascular smooth muscle cells are arranged in the so-called herringbone pattern. In regards to the mechanics of the aorta, the consequences of this type of anisotropy have not been fully discussed in literature so far. In this end, a novel hyperelastic constitutive law is proposed which accounts for the dispersive, transmural alignment of vascular smooth muscle cells and their characteristic length-tension behaviour. The model is calibrated with experimental data and is applied to the simulation of an aortic ring under in vivo conditions. By approximating the geometry of the aorta as a layered, thick-walled cylinder, the corresponding quasistatic, mechanical boundary value problem is solved semi-analytically. It is shown that the herringbone pattern induces shear deformation and equalises the normal stress gradients in the aortic wall. Since arterial vessels are able to actively adapt and alter the alignment and activity of smooth muscle cells, the existence of the herringbone pattern is in accordance with Fung's principle of optimal operation.

Yes / To reproduce the natural flow topography in a laboratory environment, it is crucial to recapture its bed condition in order to ensure the accurate representation. Water-worked bed represents a state-of-the-art experimentally formed bed to imitate the natural-formed channel in most rivers or natural streams. Recently, this technique has been intensively studied through experimental and computational approaches; however, its actual influence towards the near-bed flow as compared to experimentally prepared rough bed in well-packed bedform order are still yet to be investigated deeply. This experimental study systematically investigated and compared the differences in velocity distribution and three-dimensional (3D) turbulence characteristics, including turbulence intensities and Reynolds stresses, between uniform smooth bed, laboratory-prepared rough bed and water-worked bed open channel flows. The flow comparisons were concentrated at near-bed region where clear flow behaviour change can be observed. Through these comparisons, the study inspected the characteristics of water-worked bedform thoroughly, in order to inform future experimental research that tries to reproduce natural stream behaviours. / the Major State Basic Research Development Grant No. 2013CB036402 from Tsinghua University. The support from the Major State Basic Research Development Program (973 program) of China is also greatly appreciated. We also acknowledge the National Key Research and Development Project from the Ministry of Science and Technology during the Thirteenth Five-year Plan Period (Grant No. 2017YFC0403600) and the Science and Technology Projects State Grid Corporation of China (Grant No. 52283014000T).

[ES] La presente tesis aborda la Interacción Humano-Robot para tareas industriales de tratamiento superficial, con el objetivo de obtener una verdadera sinergia entre el operador humano y el sistema robotizado, así como un funcionamiento robusto. En concreto, la tesis establece las bases sobre las cuales un robot con asistencia por teleoperación o autónomamente interacciona con los humanos y con los otros robots en la zona de trabajo. Las propuestas se validan mediante experimentación real utilizando hasta dos robots manipuladores 6R y 7R respectivamente. Las principales contribuciones son: - Asistencia robótica para el lijado industrial con aproximación suave a la superficie y restricciones de límite - Control de robots bimanuales usando teleoperación asistida para tareas de tratamiento superficial - Interfaz basada en Realidad Aumentada para la teleoperación de robots bimanuales La aplicación de técnicas de Control en Modo Deslizante (SMC, por sussiglas en inglés) tanto convencional como no convencional y una arquitectura de control basada en prioridades son las herramientas clave para el desarrollo de estas contribuciones. / [CA] La present tesi aborda la Interacció Humà-Robot per a tasques industrials de tractament de superfícies, amb l'objectiu d'obtindre una veritable sinergia entre l'operador humà i el sistema robotitzat, així com un funcionament robust. En concret, la tesi estableix les bases sobre les quals un robot amb assistència per teleoperació o autònomament interacciona amb els humans i amb els altres robots a la zona de treball. Les propostes es validen mitjançant experimentació real utilitzant fins a dos robots manipuladors 6R i 7R, respectivament. Les principals contribucions són: - Assistència robòtica per al poliment industrial amb aproximació suau a la superfície i restriccions de límit - Control de robots bimanuals emprant teleoperació assistida per a tasques de tractament superficial - Intefaç basada en Realitat Augmentada per a la teleoperació de robots bimanuals L'aplicació de tècniques de Control en Mode Lliscant (SMC, per les seues sigles en anglés)tant convencional com no convencional i una arquitectura de control basada en prioritats són les eines clau pel desenvolupament d'aquestes contribucions. / [EN] The present thesis work addresses Human-Robot Interaction for industrial surface treatment tasks, aiming to attain a true synergy between the human operator and the robot system, as well as a robust performance. Specifically, this thesis establishes the basis on which a robot, either assisted by teleoperation or working autonomously, interacts with humans and with other robots in its working area. These proposals are validated through real experimentation using up to two robot manipulators, 6R and 7R respectively. The main contributions are: - Robotic assistance for industrial sanding with a smooth approach to the surface and boundary constraints - Bimanual robot control using assisted teleoperation for surface treatment tasks - Augmented reality-based interface for bimanual robot teleoperation The appliance of conventional and non-conventional Sliding Mode Control (SMC) techniques and a priority-based control architecture are the fundamental tools for the development of these contributions. / García Fernández, A. (2023). Robust human-robot collaboration for polishing tasks in the automotive industry [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/198673

In den letzten Jahren sind immer mehr erschwingliche Kamera-Sensoren mit einer zunehmenden Vielfalt optischer Abbildungsfunktionen verfügbar geworden. Low-Cost-Optiken können aufgrund höherer Toleranzen und unterschiedlicher optischer Materialien von der gewünschten Lochkamera Metrik abweichen. Weitwinkel- und Fischaugenobjektive, verzerrende katadioptrische Objektive (spiegelnd und refraktiv) und andere ungewöhnliche Objektive weichen von der Annahme des Modells einer Lochkamera mit einer Brennweite ab. Actionkameras können die gesamte Umgebung mit zwei Objektiven abbilden, diese entsprechen meist nicht mehr dem Lochkameramodell. Kameras werden auch für Messaufgaben hinter zusätzlichen optischen Elementen eingesetzt. Die vorliegende Arbeit erweitert die ersten Erkenntnisse im Bereich der differenzierbaren (glatten) Kameramodelle ohne Einschränkungen. Viele existierende Modelle sind auf bestimmte Objektivtypen spezialisiert. In dieser Arbeit werden mehrere solcher allgemeinen Modelle eingeführt, ohne dass eine global feste Brennweite und spezielle Anforderungen an die Symmetrie der Abbildung erforderlich sind. Eine Einführung alternativer Fehlermetriken im Objektraum bringt auch enorme Rechenvorteile, da eine Abbildungsrichtung analytisch berechnet und viele der Berechnungsergebnisse konstant gehalten werden können. Zur Initialisierung solcher Modelle wird in dieser Arbeit eine generische lineare Kamera vorgestellt. Das wesentliche Merkmal dabei ist eine künstliche Transformation in höhere Dimensionen, welche mit linearen Verfahren weiterverwendet werden. Sie modellieren bereits nichtlineare Verzerrungen und Asymmetrien. Eine Multikamera-Kalibrierungssoftware wird ebenfalls beschrieben und implementiert. Das Ergebnis der Arbeit ist ein theoretischer Rahmen für glatte Kameramodelle im Objektraum selbst – anstelle der Abbildung in den Bildraum – mit mehreren konkreten Modellvorschlägen, Implementierungen und dem angepassten und erweiterten Kalibrierungsprozess. / In recent years, more and more affordable camera sensors with an increasing variety of optical imaging features have become available. Low-cost optics may deviate from the desired pinhole metric due to higher tolerances and different optical materials. Wide-angle and fisheye lenses, distorting catadioptric lenses (specular and refractive) and other unusual lenses deviate from the single focal pinhole camera model assumption, which is sometimes intentional. Action cameras can map the entire environment using two lenses, these usually no longer correspond to the pinhole camera model. Cameras are also used for measuring tasks behind additional optical elements – with unforeseeable deviations in the line of sight. The present work expands the first findings in the field of differentiable (smooth) camera models without constraints. Many existing models specialise in certain types of lenses. In this work, several such general models are introduced without requiring fixed global focal length and symmetry requirements. An introduction of alternative error metrics in the object space also gives enormous computational advantages, since one imaging direction can be calculated analytically and many of the calculation results can be kept constant. For the generation of meaningful starting values of such models, this work introduces a generic linear camera. The essential feature of is an artificial transformation into higher dimensions. These transformed coordinates can then continue to be used with linear methods. They already model non-linear distortions and asymmetries. A multi-camera calibration software that efficiently implements these models is also described and implemented. The result of the work is a theoretical framework for smooth camera models in the object space itself - instead of the established mapping into the image space - with several concrete model proposals, implementations and the adapted and extended calibration process.

Die Migration und Proliferation vaskulärer Zellen spielt eine entscheidende Rolle in der Pathogenese atherosklerotischer Gefäßwandveränderungen und trägt zudem in hohem Maße zu restenosebedingten Komplikationen interventioneller Therapien der Atherosklerose bei. Dies bedingt ein großes Interesse an pharmakologischen Interventionsmöglichkeiten zur Prävention / Therapie atherosklerotischer und restenotischer vaskulärer Läsionen. Dabei kommen neben lokal applizierbaren Substanzgruppen insbesondere Pharmaka in Betracht, die bereits Anwendung zur Behandlung metabolischer Risikofaktoren kardiovaskulärer Erkrankungen finden. Hierzu gehören insbesondere die oralen Antidiabetika vom Typ der Thiazolidindeone, die als Liganden für den "Peroxisome Proliferator-Activated Receptor gamma" (PPARg) agieren. PPARs sind eine Gruppe neuer Regulatoren der Genexpression, für die in den vergangenen Jahren eine Reihe vaskulärer Wirkungen nachgewiesen wurden. Wir konnten zeigen, daß die Proliferation und Migration von Gefäßmuskelzellen durch PPARg-Liganden gehemmt wird. Untersuchungen zu den beteiligten Signalübertragungsschritten ergaben, daß die pharmakologische Aktivierung von PPARg in Gefäßmuskelzellen insbesondere die durch die Mitogen-aktivierten Protein Kinasen ERK1/2 vermittelte Signaltransduktion beeinflußt. Diesbezüglich haben wir nachgewiesen, daß PPARg in Gefäßmuskelzellen die mitogene Signaltransduktion via ERK1/2 MAPK -> Elk-1 -> c-fos und die chemotaktische Signalübertragung via ERK1/2 MAPK -> Ets-1 -> Matrixmetalloproteinase-9 hemmt. Wir konnten ferner zeigen, daß PPARg-Liganden die Endothelzellmigration hemmen, die durch die Neovaskularisation atherosklerotischer Plaques und der damit verbundenen erhöhten Vulnerabilität einer Plaqueruptur eine Rolle in der Pathobiologie der Atherosklerose spielt. Diese migrationshemmende Wirkung der PPARg-Liganden basiert vermutlich auf einer Inhibition der für die Endothelzellmigration erforderlichen Signaltransduktion über den PI3 Kinase -> Akt -> eNOS Pathway. Die Inhibition dieses Signalwegs könnte die Folge der von uns beobachteten PPARg-Ligand-induzierten Expression der Phosphatase PTEN sein, die den PI3K -> Akt Signalweg negativ reguliert und die Aktivierung und Phosphorylierung von Akt inhibiert. Somit haben PPARg-aktivierende Liganden eine wichtige Funktion in der Behandlung der metabolischen Hauptrisikofaktoren kardiovaskulärer Erkrankungen, spielen aber gleichzeitig eine vermutlich ebenso wichtige Rolle in der Protektion atherosklerotischer und restenosebedingter Gefäßwandveränderungen durch direkte vaskuläre Effekte. / Migration and proliferation of vascular cells not only play an important role in the pathogenesis of atherosclerotic lesion formation, but also contribute to restenosis after therapeutic angioplasty. Therefore, pharmacological strategies for the prevention and/or treatment of atherosclerotic and restenotic vascular lesions are of great clinical interest. This involves substances that can be locally administered via stents, as well as agents that are already in clinical use for the treatment of metabolic risk factors. Among the latter, antidiabetic thiazolidinediones which function as ligands for the "peroxisome proliferator-activated receptor gamma" (PPARg), have been identified as promising drugs to target vascular lesion formation. PPARs constitute a group of novel regulators of gene expression, that exert several vascular effects. We report that vascular smooth muscle cell proliferation and migration is inhibited by PPARg-ligands. Investigating the signalling steps that are involved, we find that pharmacological activation of PPARg interferes with signal transduction through the mitogen-activated protein kinases ERK1/2 in vascular smooth muscle cells. We demonstrate that PPARg inhibits mitogenic signal transduction via ERK1/2 MAPK -> Elk-1 -> c-fos and also blocks chemotactic signalling through the ERK1/2 MAPK -> Ets-1 -> matrix metalloproteinase-9 pathway in vascular smooth muscle cells. We also showed that PPARg-ligands inhibit endothelial cell migration, which participates in the neovascularization of atherosclerotic plaques, thereby contributing to plaque destabilization and increased risk of plaque hemorrhage. This antimigratory action of PPARg-ligands results from an inhibition of signal transduction via PI3 Kinase -> Akt -> eNOS, a pathway that is crucial for endothelial cell migration. Since we observed a PPARg-ligand-induced upregulation of PTEN, a phosphatase that negatively regulates the PI3K -> Akt signalling pathway, this might constitute the mechanism by which PPARg-ligands inhibit endothelial cell migration. In conclusion, PPARg-activating ligands may provide a dual benefit in cardiovascular disease by ameliorating metabolic risk factors, as well as protecting the vasculature from atherosclerotic and restenotic alterations through direct vascular effects.

Die Ergebnisse der Arbeit weisen mehrfach auf eine defizitäre IL-10 Produktion in Alveolarmakrophagen von Asthmatikern hin. Die reduzierte IL-10 Expression auf Protein- und Genebene korrelierte mit einer erhöhten Produktion proinflammatorischer Zytokine (TNF-?, MIP1-?, GM-CSF). Diese Beobachtung impliziert einen Defekt in der IL-10 Synthese, der in einer verstärkten und prolongierten pulmonalen Entzündungsantwort resultiert. Daraus läßt sich schlußfolgern, dass beim Asthma bronchiale eine Dysbalance zwischen pro- und antiinflammatorischen Zytokinen pathogenetisch von Bedeutung ist. Die verringerte Sensitivität von Alveolarmakrophagen auf die inhibitorischen Effekte von exogenem IL-10 im Vergleich zu Blutmonozyten ist durch Unterschiede in den Mechanismen der Signaltransduktion bedingt (37, 54). Der Nachweis der Expression von proinflammatorischen Zytokinen in Bronchialmyozyten (RANTES, IL-8) führte zu einer Neubewertung dieser Zellen als Immuneffektorzellen in der Pathogenese des Asthma bronchiale. Neben der Kontraktilität sind Myozyten auch aktiv an der Aufrechterhaltung der Atemwegsentzündung beteiligt. Die inhibitorischen Effekte von IL-10 und IL-13 auf die Synthese proinflammatorischer Chemokine (RANTES, IL-8, MIP-1() in migrierten Entzündungszellen und residenten Bronchialmyozyten konnten in verschiedenen Arbeiten gut dokumentiert werden. Die Vielzahl antiinflammatorischer Effekte von IL-10, die sich auf unterschiedliche Zellsysteme wie Monozyten, Makrophagen und Bronchialmyozyten erstrecken, unterstreicht die pathogenetische Bedeutung dieses Zytokins. Der molekulare Mechanismus, welcher die IL-10 Wirkung vermittelt, ist derzeit noch nicht vollständig aufgeklärt. Angenommen wird eine rezeptorvermittelte Inhibition von Transkriptionsfaktoren des Stat Systems und NF-(B (76). Zukünftige molekularbiologische und klinische Studien sind jedoch notwendig, um den Kenntnisstand der Effekte antiinflammatorischer Zytokine zu vertiefen, und die Gabe von rekombinantem IL-10 als möglichen Ansatz zur Therapie chronisch entzündlicher Lungenerkrankungen zu evaluieren (81). / The results of this present thesis show a deficiency of IL-10 production in alveolar macrophages in asthma. The reduced IL-10 expression on protein and m-RNA level correlated with an increased production of pro-inflammatory cytokines such as TNF-(, MIP1- ( and GM-CSF. These observations implicate an impaired IL-10 synthesis in asthma with a subsequent prolongation of the inflammatory response. This leads to the conclusion that a dysbalance between pro- and anti-inflammatory cytokines is present in asthma and may be therefore of pathogenetic importance. The reduced sensitivity of alveolar macrophages to the inhibitory effects of exogenous IL-10 compared to peripheral blood monocytes may be caused by different signal transduction mechanisms. The expression of the proinflammatory cytokines RANTES and IL-8 in cultured human airway smooth muscle cells led to the conclusion that airway smooth muscle cells may act beside their contractile function as immunomodulatory cells in the pathogenesis of asthma. The inhibitory effects of IL-10 and IL-13 on the synthesis of proinflammatory cytokines (RANTES, IL-8, MIP1-() in immigrated inflammatory cells and resident cells such as airway smooth muscle cells have been shown in several publications that are part of the present thesis. The numerous antiinflammatory effects of IL-10 on different inflammatory cell systems such as monocytes/macrophages and smooth muscle cells underline the pathogenetic importance of this cytokine. The molecular mechanisms that mediate the IL-10 effects involve the transcription factors NF-(B and the Stat-System. Future studies are needed to determine the molecular mechanisms of the anti-inflammatory effects of IL-10 and IL-13 more deeply and to evaluate their application for the therapy of chronic inflammatory pulmonary diseases.

Anhand von immunhistochemischen Färbemethoden wurde die Expression von CD 31 (immunhistochemischer Marker für Endothelzellen) und -Aktin (immunhistochemischer Marker für glatte Muskelzellen) auf Zellen der intramyokardialen Blutgefäße herztransplantierter Patienten histomorphometrisch ausgewertet. In die Bewertung der myokardialen Strukturen ging auch die Untersuchung der jeweiligen zugehörigen HE-Färbungen mit ein. Ziel dieser Untersuchungen war die Beurteilung von qualitativen und quantitativen Unterschieden dieser Marker während eines Untersuchungszeitraumes von 14 Monaten nach Herztransplantation (HTx) bei Patienten mit einer angiographisch diagnostizierten Transplantatvaskulopathie (TVP) mit Patienten ohne einer prä- bzw. postmortem diagnostizierten TVP. Der Einsatz dieser Immunomarker richtete sich hierbei auf die selektive Darstellung der terminalen Strombahn mit der Fragestellung, ob ein intramyokardiales morphologisches Korrelat zu der TVP der epikardialen Blutgefäße existiert und ob die histomorphometrische Auswertung der bewerteten Strukturen eine mögliche Frühdiagnose der TVP nach HTx zuläßt. Des weiteren sollte eine mögliche Assoziation der TVP mit den demographischen Charakteristika sowie der Anzahl und dem Schweregrad der Rejektionsepisoden der untersuchten Patienten überprüft werden. Als Basis dienten dabei in Paraffin eingebettete rechtsventrikuläre Rejektionskontrollbiopsien, die im Rahmen der routinemäßig durchgeführten Abstoßungsdiagnostik entnommenen wurden. Nach morphologischer Bewertung dieser Schnitte im Hinblick auf die Existenz und den Schweregrad einer Abstoßungsreaktion wurden diese immunhistochemisch aufbereitet und anschließend quantitativausgewertet. Im Rahmen dieser Arbeit weist die quantitativ- histomorphometrische Erfassung intramyokardialer Blutgefäße in rechtsventrikulären Rejektionskontrollbiopsien auf die mögliche Frühdiagnose einer TVP nach HTx hin. Dieses Verfahren könnte die zur Zeit verwendeten diagnostischen Methoden ergänzen. Jedoch sind noch weitere prospektive klinische Studien für die Validierung dieser Ergebnisse notwendig. / In this study, immunohistochemical and histomorphometric investigations were performed in order to investigate the expression of CD 31 (immunohistochemical marker for endothelial cells) and -Aktin (immunohistochemical marker for smooth muscle cells) on cells of intramyocardial blood vessels in heart transplant (HTx) patients. The evaluation of myocardial structures also implicated the investigation of the corresponding histological H & E stainings. The aim of this study was to ascertain whether HTx patients with angiographic evidence of graft vessel disease (GVD) showed different qualitative and quantitative expression of the above mentioned immunomarkers than HTx patients with no angiopraphic or postmortem signs of this phenomenon. The investigation time included the first 14 months after HTx. The use of these immunomarkers made possible the selective representation of the terminal vascular system to answer the question, as to whether there existed an intramyocardial morphological correlate to GVD of epicardial coronary arteries and whether histomorphometric evaluation of small vessels permits early diagnosis of GVD after HTx. In addition, demographic data, as well the number and grade of rejection episodes of the studied patients, were reviewed in order to ascertain whether there might be an association of these characteristics with GVD. The material studied consisted of paraffin-embedded right ventricular rejection control samples from routine postoperative diagnostic management, which were used to reveal acute rejection episodes. After morphological evaluation of histological slices with regard to the appearence and severity of acute rejection, immunohistochemical staining was performed and finally a quantitative investigation was done. According to the results of this study, quantitative histomorphometric investigations of intramyocardial blood vessels in right ventricular rejection control samples permit the early diagnosis of GVD after HTx and completes the present diagnostic tools. But further prospective clinical studies are necessary to confirm these results.

Wong Cheuk Ying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 101-124). / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iv / Acknowledgement --- p.vi / List of Abbreviations --- p.vii / Chapter Chapter 1. --- General Introduction --- p.1 / Chapter Chapter 2. --- Methods --- p.4 / Chapter 2.1 --- Measurement of cAMP and cGMP in VSMCs --- p.4 / Chapter 2.1.1 --- Cell culture --- p.4 / Chapter 2.1.2 --- Enzyme-immunoassay colorimetric measurement for cAMP and cGMP --- p.5 / Chapter 2.1.3 --- Statistical analysis --- p.6 / Chapter 2.2 --- Measurement of apoptosis in VSMCs and bone marrow-derived stem cells --- p.6 / Chapter 2.2.1 --- Cell culture --- p.6 / Chapter 2.2.2 --- Hoechst33258 --- p.7 / Chapter 2.2.3 --- Cell Death ELISA plus --- p.7 / Chapter 2.2.4 --- Protein extraction and Western blot analysis of PKG expression --- p.8 / Chapter 2.2.5 --- Statistical analysis --- p.9 / Chapter 2.3 --- Measurement of cell proliferation in VSMCs and bone marrow-derived stem cells --- p.9 / Chapter 2.3.1 --- Cell culture --- p.9 / Chapter 2.3.2 --- Cell count --- p.10 / Chapter 2.3.3 --- MTT assay --- p.11 / Chapter 2.3.4 --- BrdU-(5`Bromo-2-deoxyuridine) ELISA colorimetric assay --- p.11 / Chapter 2.3.5 --- Statistical analysis --- p.12 / Chapter Chapter 3. --- Effects of hyperglycemia on CGRP-induced cAMP response in VSMCs / Chapter 3.1 --- Introduction --- p.13 / Chapter 3.2 --- Results --- p.18 / Chapter 3.3 --- Discussion --- p.22 / Chapter Chapter 4. --- Role of cGMP and protein kinase G in regulation of apoptosis in VSMCs / Chapter 4.1 --- Introduction --- p.26 / Chapter 4.2 --- Results --- p.30 / Chapter 4.3 --- Discussion --- p.44 / Chapter Chapter 5. --- Role of protein kinase G in regulation of proliferation in VSMCs / Chapter 5.1 --- Introduction --- p.55 / Chapter 5.2 --- Results --- p.58 / Chapter 5.3 --- Discussion --- p.67 / Chapter Chapter 6. --- Effects of aging and eNOS- and iNOS-gene deletion (using eNOS- and iNOS-knockout mice) on apoptosis of VSMCs / Chapter 6.1 --- Introduction --- p.73 / Chapter 6.2 --- Results --- p.76 / Chapter 6.3 --- Discussion --- p.79 / Chapter Chapter 7. --- Role of protein kinase G in regulation of apoptosis and proliferation of bone marrow stromal stem cells / Chapter 7.1 --- Introduction --- p.81 / Chapter 7.2 --- Results --- p.84 / Chapter 7.3 --- Discussion --- p.92 / Chapter Chapter 8. --- Overall discussion --- p.95 / Chapter Chapter 9. --- References --- p.101

A couple of discretization schemes, based on an FE-like tessellation of the domain and polynomial reproducing, globally smooth shape functions, are considered and numerically explored to a limited extent. The first one among these is an existing scheme, the smooth DMS-FEM, that employs Delaunay triangulation or tetrahedralization (as approximate) towards discretizing the domain geometry employs triangular (tetrahedral) B-splines as kernel functions en route to the construction of polynomial reproducing functional approximations. In order to verify the numerical accuracy of the smooth DMS-FEM vis-à-vis the conventional FEM, a Mindlin-Reissner plate bending problem is numerically solved. Thanks to the higher order continuity in the functional approximant and the consequent removal of the jump terms in the weak form across inter-triangular boundaries, the numerical accuracy via the DMS-FEM approximation is observed to be higher than that corresponding to the conventional FEM. This advantage notwithstanding, evaluations of DMS-FEM based shape functions encounter singularity issues on the triangle vertices as well as over the element edges. This shortcoming is presently overcome through a new proposal that replaces the triangular B-splines by simplex splines, constructed over polygonal domains, as the kernel functions in the polynomial reproduction scheme. Following a detailed presentation of the issues related to its computational implementation, the new method is numerically explored with the results attesting to a higher attainable numerical accuracy in comparison with the DMS-FEM.

Icing severely affects society, especially in the Nordic countries. Iceaccumulation can result in critical performance problems and safetyconcerns for instance in road, air and sea transportation, transmissionlines, marine and offshore structures, wind turbines and heat exchangers.Present active ice-combating approaches possess environmental,efficiency and cost drawbacks. Thus, fabricating icephobic surfaces orcoatings impeding ice formation (anti-icing), but facilitating ice removal(de-icing) is desired. However, different conditions in the environmentduring ice formation and growth add to the complexity of the problem.An icephobic surface that works for a certain application might not be agood candidate for another. These surfaces and the challenges are infocus in this thesis.Wetting properties are important for ice formation on surfaces fromthe liquid phase (often supercooled water), where the water repellency ofthe surfaces could enhance their anti-icing effect. Considering this,different hydrophobic and superhydrophobic surfaces with differentchemistry, morphology and roughness scale were prepared. Since anyinduced wetting state hysteresis on hydrophobic surfaces could influencetheir performance, the wetting stability was investigated. In particulardynamic wetting studies of the hydrophobic surfaces revealed whatsurface characteristics benefit a stable wetting performance. Further, theeffect of temperature, particularly sub-zero temperatures, on the wettingstate of flat and nanostructured hydrophobic surfaces was investigated.This was complemented with studies of the wetting stability of sessilewater droplets on flat to micro- and multi-scale (micro-nano) roughhydrophobic samples in a freeze-thaw cycle. To be consistent with mostapplications, all temperature-controlled experiments were performed inan environmental condition facilitating frost formation. Further, antiicingproperties of hydrophobic surfaces with different topography butsimilar chemistry were studied by freezing delay measurements.A dynamic wetting study using hydrophobic samples with similarchemistry but different topography revealed that multi-scale roughnesscould benefit the wetting stability. However, when these surfaces areutilized at low temperatures the wetting hysteresis observed during acooling/heating cycle is significant. Such a temperature-inducedhysteresis is also significant on superhydrophobic surfaces. I attributethis to condensation followed by frost formation facilitating spreading of  the supercooled water droplet. The freezing delay measurementsdemonstrate no significant effect of surface topography on anti-icingproperties of hydrophobic surfaces, however the flat surfaces showed thelongest delay. These findings are in agreement with heterogeneous icenucleation theory, suggesting preferential ice nucleation in concave sites,provided they are wetted.In the second part of this thesis, I consider the findings from theprevious part illustrating the limitations of (super)hydrophobic surfaces.The de-icing properties of hydrophilic surfaces with a hydration waterlayer, hypothesized to lubricate the interface with ice, were studied. Heretemperature-controlled shear ice adhesion measurements, down to -25oC, were performed on an adsorbed layer of a polymer, either bottle-brushstructured poly(ethylene oxide) or linear poly(ethylene oxide). The iceadhesion strength was reduced significantly on the bottle-brushstructured polymer layer, specifically at temperatures above -15 oC,whereas less adhesion reduction was observed on the layer formed by thelinear polymer. These findings are consistent with differential scanningcalorimetry (DSC) data, demonstrating that the hydration water, boundto the bottle-brush structured polymer, is in the liquid state at thetemperatures where de-icing benefit is observed. Further, continuingwith the hypothesis of the advantage of surfaces with a natural lubricantlayer for de-icing targets, I studied shear ice adhesion on the molecularlyflat basal plane of hydrophilic mica down to -35 oC. Interestingly, ultralowice adhesion strength was measured on this surface. I relate this to theproposed distinct structure of the first ice-like but fluid water layer onmica, with no free OH groups, followed by more bulk liquid-like layers.This combined with the molecularly smooth nature of mica results in aperfect plane for ice sliding. / Isbildning har en stark inverkan på samhället, speciellt i de nordiskaländerna. Isuppbyggnad kan resultera i kritiska prestandaproblem ochsäkerhetsrisker inom t.ex. väg-, luft-, och sjötransport, kraftledningar,marina- och offshorestrukturer, vindkraftverk och värmeväxlare.Nuvarande aktiva isbekämpningsmetoder uppvisar brister i avseende påmiljö, effektivitet och kostnad. Det finns därmed ett behov av attframställa ytor eller ytbeläggningar som förhindrar isbildning (antiisning)eller underlättar borttagandet av redan bildad is (avisning). Dockkompliceras problemet av de många olika förhållanden under vilka is kanbildas. En beläggning som fungerar för en viss tillämpning behöver intenödvändigtvis vara en bra kandidat för en annan. Dessa ytor ochutmaningar relaterade till dem är i fokus i denna avhandling.Vätningsegenskaper är viktiga för isbildning på ytor från vätskefas(ofta underkylt vatten), och det har visats att vattenavstötande ytor i vissasammanhang kan motverka isbildning. Med detta i åtanke framställdesolika hydrofoba och superhydrofoba ytor, med varierande kemi,morfologi och ytråhet. Eftersom en förändring i de hydrofoba ytornasvätningsegenskaper kan påverka deras funktion studerades vätningsstabilitetenför dessa ytor. I synnerhet dynamiska vätningsstudier av dehydrofoba ytorna avslöjade vilka ytegenskaper som är fördelaktiga förvätningsstabiliteten. Vidare studerades hur temperaturen, särskilt undernoll grader, påverkar vätningstillståndet på släta och nanostruktureradehydrofoba ytor. Arbetet kompletterades med studier av vätningsstabilitetenför vattendroppar på släta samt mikro- och multistrukturerade(mikro-nano) hydrofoba ytor under flera frysningsupptiningscykler.För att vara i linje med de flesta tillämpningar, utfördesalla temperaturkontrollerade mätningar i en miljö där frost kunde bildaspå ytorna. Anti-isegenskaperna hos de hydrofoba ytorna med varierandetopografi men samma kemi studerades vidare genom att studera hur långtid det dröjde innan en vattendroppe på ytan fryste vid en visstemperatur.De dynamiska vätningsstudierna på hydrofoba ytor med samma kemimen olika topografi avslöjade att en ytråhet på flera längdskalor kan haen positiv inverkan på vätningsstabiliteten. När dessa ytor är exponeradeför låga temperaturer är dock vätningshysteresen under en nedkylnings-/uppvärmnings-cykel significant. Den temperatur-inducerade hysteresenär också betydande för superhydrofoba ytor. Detta tillskriver jag  kondensation på ytan som följs av frostbildning, vilket i sin tur möjliggörspridning av den underkylda vattendroppen på ytan. Mätning avfördröjningen i frysningsförloppet påvisade ingen betydande effekt avyttopografin för hydrofoba ytor, men släta hydrofoba ytor uppvisade denlängsta fördröjningen. Dessa resultat är i överensstämmelse med rådandeheterogen iskärnbildningsteori, som visar på fördelaktig iskärnbildningpå konkava delar av ytan, förutsatt att dessa väts.I den andra delen av avhandlingen utnyttjar jag observationerna frånden första delen vilka illustrerade begränsningarna för superhydrofobaytor, och söker en annan lösning. Avisningsegenskaper för hydrofilastarkt hydratiserade ytor studerades, med hypotesen att hydratiseringkan smörja gränsskiktet med is. Temperatur-kontrolleradeisadhesionsmätningar ned till -25 °C utfördes på adsorberade skikt av enpolymer med många sidokedjor av polyetylenoxid (”bottle-brush”), såvälsom på ett skikt av linjär polyetylenoxid. Isadhesionen blev kraftigtreducerad på ”bottle-brush”-polymeren, speciellt vid temperaturer högreän -15°C. Däremot kunde knappast ingen minskad isadhesion observerasför den linjära polymeren. Dessa observationer överensstämmer meddifferentialskanningskalorimetri (DSC) data, som visar att dethydratiserade vattenskiktet, vilket är bundet till ”bottle-brush”-polymeren, är i vätskeform vid de temperaturer där avisningsfördelar ärobserverade. För att vidare undersöka hypotesen att det vore fördelaktigtmed ett naturligt smörjande skikt på ytan för att uppnå godaavisningsegenskaper, utförde jag isadhesionsmätningar på molekylärtsläta glimmerytor ner till -35 °C. Intressant nog uppmättes extremt lågisadhesion på denna yta. Detta relaterar jag till den föreslagna utprägladehydratiseringsstrukturen, bestående av ett första is-liknande vattenskiktutan fria OH-grupper, följt av ett mer bulkliknande skikt. Detta ikombination med den molekylärt släta naturen hos glimmer resulterar iett perfekt plan för isen att glida på. / <p>QC 20160504</p> / TopNano