This thesis includes the design, production and measurement of a wideband dualpolarized X-band aperture-coupled microstrip patch antenna. The wideband and dual-polarized operation is achieved through the use of H-shaped coupling slots. Therefore, the equivalent circuit modeling of a microstrip line fed H-shaped slot is also studied in this thesis. A step-by-step procedure is followed during the design process of the dual-polarized aperture-coupled microstrip antenna. First, an aperture-coupled microstrip antenna with a single rectangular slot, that exhibits a wideband characteristic for single polarization, is designed. Then, the design procedure is repeated for an antenna with H-shaped slot in order to satisfy the same specifications with a shorter slot. Finally, dual-polarized aperture-coupled microstrip antenna is designed. At this configuration, two H-shaped slots are used and they are placed orthogonal to each other. During the design process, the effects of antenna parameters on the input impedance characteristics of the antenna are investigated. These parametric analyses are done in CST Microwave Studio&reg / . The v designed dual-polarized wideband aperture-coupled microstrip antenna is manufactured. Simulation results and measurement results are compared. During the equivalent circuit modeling of an H-shaped slot fed by a microstrip line, an approach based on the reciprocity theorem is utilized. The method was originally proposed for rectangular shaped slots, in this thesis it is generalized for arbitrarily shaped slots. Software codes are developed in MATLAB to calculate the equivalent impedance of the slot.

Design of antenna arrays for present day requirements has to take into account both mechanical and electrical aspects. Mechanical aspects demand the antennas to have low profile, non-protruding structures, structures compatible to aerodynamic require­ments and so on. Electrical aspects may introduce several constraints either due to. technical reasons or due to readability conditions in practice. Thus, arrays of modern requirements may not fall into the category of linear or planar arrays. Further, due to the nearby environment, the elements will generate complicated individual patterns. These issues necessitate the analysis and synthesis of antenna arrays which are arbi­trary as far as the orientation, position or the element pattern are concerned. Such arrays which may be called arbitrary arrays are being investigated in this thesis. These investigations have been discussed as different aspects as indicated below: Radiation Characteristics of Arbitrary Arrays Radiation fields of an arbitrarily oriented dipole are obtained. Such fields are plotted for typical cases. Further, methods for transforming the electromagnetic fields are discussed. Having obtained the field due to an arbitrary element, the fields due to an arbitrary array are obtained. Factors controlling the radiation fields, like, the curvature in the array and element pattern are investigated. Radiation patterns of circular and cylindrical arrays are plotted. Synthesis of a Side Lobe Topography Requirements of a narrow beam pattern generated by an antenna array are identified. A problem of synthesizing such a pattern using an arbitrary array is formulated. The envelope of the side lobe region which may be called, the side lobe topography (sit), is included in the computation of the covariance matrix. This problem which has been formulated as a problem of minimizing a quadratic function subjected to a system of linear constraints is solved by the method of Lagrangian multipliers. An iterative procedure is used to satisfy all the requirements of the pattern synthesis. The procedure has been validated by synthesizing linear arrays and is used to synthesize circular and parabolic arrays. Patterns with tapered sit, Taylor-like sit have been synthesized. Asymmetric patterns are also synthesized. Role of sit is brought out. Shaped Beam Synthesis Synthesis of shaped broad beams is discussed. Amplitude constraints are formulated. Phase distribution is linked with the phase centre. Quadratic problems thus formu­lated are solved by the Lagrangian method of undetermined multipliers. An iterative procedure is made use of to synthesize flat topped beams as well as cosecant squared-patterns using linear arrays as well as circular arrays. Reasonable excitation dynamic has been obtained. Optimum phase centres obtained by trial and error are made use of. Effects of the Frequency and Excitation on the Synthesized Patterns In general, synthesized patterns can be sensitive towards any specific parameter either excitation or to frequency or any such parameter. Several methods can be used to observe these issues. In this thesis, these effects are also studied. Using a specific array configuration, to synthesize a specified radiation pattern, frequency is changed by 10% from the design frequency and the pattern is computed. Similarly, excitation phase distribution is rounded to the nearest available phase distribution using a digital phase shifter (say 8 bit) and the resulting pattern is computed. Further, excitation dynamic is also controlled by boosting the amplitudes of the array elements which are less than the permissible (i.e. the maximum excitation/allowed dynamic). Effects of these variations are also recorded. It appears that reasonable patterns can be obtained, in spite of significant variations in these parameters in most of the cases. Reconfigurable Arbitrary Arrays It would be very useful if a single array configuration can be used for different ap- plications. This may be either for the different phases of a single application or for different applications that may be required at different times. Attempts are made to synthesize a variety of patterns from a single array. Such arrays which may be called as reconfigurable arrays can be of much use. Obviously, the excitations are different for different patterns. Both narrow beams, as well as shaped broad beams, with different side lobe topographies have been synthesized using a single array.

<p>The use of synthetic materials for tissue and organ reconstruction, i. e. tissue engineering, has become a promising alternative to current surgical therapies and may overcome the shortcomings of the methods in use today. The challenge is in the design and reproducible fabrication of biocompatible and bioresorbable polymers, with suitable surface chemistry, desirable mechanical properties, and the wanted degradation profile. These material properties can be achieved in various manners, including the synthesis of homo- and copolymers along with linear and star-shaped architectures. In many applications the materials’ three-dimensional structure is almost as important as its composition and porous scaffolds with high porosity and interconnected pores that facilitate the in-growth of cells and transportation of nutrients and metabolic waste is desired.</p><p>In this work linear and star-shaped polymers have been synthesized by ring-opening polymerization using a stannous-based catalyst and a spirocyclic tin initiator. A series of linear copolymers with various combinations of 1,5-dioxepane-2-one (DXO), Llactide (LLA) and ε-caprolactone (CL) have been polymerized using stannous octoate as catalyst. It is shown that the composition of the polymers can be chosen in such a manner that the materials’ mechanical and thermal properties can be predetermined. A solvent-casting and particulate leaching scaffold preparation technique has been developed and used to create three-dimensional structures with interconnected pores. The achieved physical properties of these materials’ should facilitate their use in both soft and hard tissue regeneration.</p><p>Well defined star-shaped polyesters have been synthesized using a spirocyclic tin initiator where L-lactide was chosen as a model system for the investigation of the polymerization kinetics. Neither the temperature nor the solvent affects the molecular weight or the molecular weight distribution of the star-shaped polymers, which all show a molecular weight distribution below 1.19 and a molecular weight determined by the initial monomer-to-initiator concentration.</p>

Ziele wie eine hohe Auflösung und ein hoher Durchsatz sind bisher in der Elektronenstrahllithografie nicht gleichzeitig erreichbar; es existieren daher die Belichtungskonzepte Gaussian-Beam und Variable-Shaped-Beam (VSB), die auf Hochauflösung respektive Durchsatz optimiert sind. In dieser Arbeit wird der experimentelle Kreuzvergleich beider Belichtungskonzepte mit Hilfe chemisch verstärkter und nicht verstärkter Lacksysteme präsentiert. Als quantitativer Parameter wurde die Gesamtunschärfe eingeführt, die sich durch quadratische Addition der auflösungslimitierenden Fehlerquellen, also Coulomb-Wechselwirkungen (Strahlunschärfe), Lackprozess (Prozessunschärfe) und Proximity-Effekt (Streuunschärfe), ergibt. Für den Vergleich wurden wohldefinierte Prozesse auf 300 mm Wafern entwickelt und umfassend charakterisiert. Weitere Grundlage ist die Anpassung oder Neuentwicklung spezieller Methoden wie Kontrast- und Basedosebestimmung, Doughnut-Test, Isofokal-Dosis-Methode für Linienbreiten und Linienrauheit sowie die Bestimmung der Gesamtunschärfe unter Variation des Fokus. Es wird demonstriert, dass sich mit einer kleineren Gesamtunschärfe die Auflösung dichter Linien verbessert. Der direkte Vergleich der Gesamtunschärfen beider Belichtungskonzepte wird durch die variable Strahlunschärfe bei VSB-Schreibern erschwert. Da für die Bestimmung der Gesamtunschärfe keine Hochauflösung nötig ist, wird das Testpattern mit größeren Shots belichtet und induziert somit eine größere Gesamtunschärfe. Es wird gezeigt, dass die Prozessunschärfe den größten Anteil der Gesamtunschärfe stellt. Außerdem spielt die Streuunschärfe bei Lackdicken kleiner 100 nm und Beschleunigungsspannungen von 50 kV oder größer keine Rolle. / Up to now, targets like high resolution and high throughput can not be achieved at the same time in electron beam lithography; therefore, the exposure concepts Gaussian-Beam and Variable-Shaped-Beam (VSB) exist, which are optimized for high resolution and throughput, respectively. In this work, the experimental cross-comparison of both exposure concepts is presented using chemically amplified and non-chemically amplified resist systems. For quantification the total blur parameter has been introduced, which is the result of the quadratic addition of the resolution limiting error sources, like Coulomb interactions (beam blur), resist process (process blur) and proximity-effect (scatter blur). For the comparison, well-defined processes have been developed on 300 mm wafers and were fully characterized. Further basis is the adaption or the new development of special methods like the determination of contrast and basedose, the doughnut-test, the isofocal-dose-method for line widths and line roughness as well as the determination of the total blur with variation of the focus. It is demonstrated, that the resolution of dense lines is improved with a smaller total blur. The direct comparison of the total blur values of both exposure concepts is complicated by the variable beam blur of VSB writers. Since high resolution is not needed for the determination of the total blur, the test pattern is exposed with larger shots on the VSB writer, which induces a larger total blur. It is shown that the process blur makes the largest fraction of the total blur. The scatter blur is irrelevant using resist thicknesses smaller than 100 nm and acceleration voltages of 50 kV or larger.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Technologies such as direct broad cast satellite system (DBSS), Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellite communications , global positioning system (GPS), high accuracy airborne navigation system and a large variety of radar systems demand for high level of antenna performance. Similar is the requirement for upcoming land based wireless systems such as cellular and indoor communication systems that is needed some more specific and additional features added to the antenna to compensate for the deficiencies encountered in system's performance. Though metallic antennas are capable enough to fulfil all the operational requirements, however at very high frequencies and under hostile temperature conditions they are constrained to face certain limitations. To avoid these constraints the performance of Dielectric Resonator Antennas (DRAs) is evaluated and their new applications are proposed. In the thesis, two types of antenna applications are sought :-First is for tracking and satellite applications that needs a larger aperture coverage in elevation plane. This coverage is realized with a good CP purity by proposing two ports dual linearly polarized DRA working at X-band. The DRA is excited by two orthogonal H-shaped aperture slots yielding two orthogonal polarizations in the broadside direction. A common impedance bandwidth of 5.9% and input port isolation of -35 dB are obtained. The broadside radiation patterns are found to be highly symmetric and stable with cross polarization levels -15dB or better over the entire matching frequency band. The maximum measured gain is found to be 2.5dBi at 8.4 GHz.- The 2nd type of antenna is a dual pattern diversity antenna to be used in the Body Area Network (BAN) context. This antenna combines a slot loop and DRA yielding broadside and end-fire radiation patterns respectively. Based upon the feeding techniques, the DG antenna is further divided into two categories one with planar feeds and the other with non-planar feeds (slot loop excited by planar CPW but DRA excited by vertical monopole) .Both types are successfully designed and measured upon body when configured into different propagation scenarios. The non-planar feeds antenna allows wider common impedance bandwidths than the planar feeds (4.95% vs 1.5%).In both cases, a maximum value of DG=9.5dB was achieved when diversity performance tests were carried out in rich fading environments. This value is close to the one (10 dB) theoretically reached in a pure Rayleigh environment and was obtained with efficiencies of 70% and 85% for the slot loop and the DRA respectively. Therefore, we conclude that these antennas could be used on the shoulders or the chest of professional clothes (firemen, policemen, soldier) where full planar integration is not a key issue but where the communication must be efficient in harsh environments and for various gestures, positions and scenarios

Då dagens vapensystem blir allt effektivare med högre penetration och större verkan är det inte längre möjligt att endast lägga på mer pansar för att få tillräckligt skydd. Fordonen blir för tunga och rörligheten påverkas negativt i allt för stor grad, därför börjar nu system för aktivt skydd slå sig in på marknaden. Dessa system söker aktivt av fordonets omgivning och skjuter ner inkommande hot såsom raketer och robotar och finns redan implementerade i en rad länder i vårt närområde. Infanteriets huvudbeväpning, som mot bepansrade hot traditionellt sett varit just robotar, raketer och granater, är i många fall verkanslös i mötet med aktivt pansar. Uppsatsen undersöker vilka möjligheter som finns att med den utrustning som dagens svenska försvarsmakt är utrustad med nå verkan i mål som är skyddade av aktivt pansar. De befintliga systemen för aktivt pansar Trophy, Iron Curtain och Arena har valts som exempelsystem. De vapensystem som granskas är STRIX, Rb56, Pskott m/86, Grg m/86 samt fordonsmina 14. En slutsats är att de granskade systemen alla saknar förmåga att skydda fordonet från hot som kommer rakt ovanifrån, detta medför att STRIX är fullt fungerande mot ett fordon skyddat av aktivt pansar. / Since today's weapons systems are becoming more efficient with higher penetration and greater efficacy, it is no longer possible to only put on more armor to get adequate protection. The vehicles become too heavy and mobility is adversely affected to an excessive degree, because of this systems for active protection are now breaking into the market. These systems are actively scanning the vehicle's surroundings and shoot down incoming threats such as rockets and robots and are already implemented in a number of countries in our region. The infantry's main armament against armored units, which traditionally have been just missiles, rockets and grenades are in many cases useless meeting with active protection systems. The paper examines the possibilities of reaching effect in targets equipped with active armor using the equipment available to the Swedish armed forces today. The existing active protection systems Trophy, Iron Curtain and Arena have been chosen as example systems. The weapons systems examined are STRIX , Rb56 , Pskott m/86 , Grg m/86 and Fordonsmina 14. One conclusion is that the audited systems all lack the ability to protect the vehicle from threats that come from directly above; this means that STRIX is fully functional to a vehicle protected by an active protection system.

Surface-assisted directed assembly allows ultrasoft and replusive functional polymeric “colloids” to assemble into the organized supramolecular ultrathin films on a monomolecular level. This study aims at achieving a fundamental understanding of molecular morphology and responsive behavior of major classes of branched star-shaped polymers (star amphiphilic block copolymers and star polyelectrolytes) and their aggregation into precisely engineered functional ultrathin nanofilms. Thus, we focus on elucidating the role of molecular architecture, chemical composition, and intra/intermolecular interactions on the assembly behavior of highly-branched entities under variable environmental and confined interfacial conditions. The inherent molecular complexity of branched architectures facilitates rich molecular conformations and phase states from the combination of responsive dynamics of flexible polymer chains (amphiphilic, ionizable arms, multiple segments, and free chain ends) and extened molecular design parameters (number of arms, arm length, and segment composition/sequence). These marcromolecular building components can be affected by external conditions (pH, salinity, solvent polarity, concentration, surface pressure, and substrate nature) and transformed into a variety of complex nanostructures, such as two-dimensional circular micelles, core/shell unimicelles, nanogel particles, pancake & brush micelles, Janus-like nanoparticles, and highly nanoporous fractal networks. The fine balance between repulsive mulitarm interactions and surface energetic effects in the various confined surfaces and interfaces enables the ability to fabricate and tailor well-organized ultrathin nanofilms. The most critical findings in this study include: (1) densely packed circular unimicelle monolayers from amphiphilic and amphoteric multiblock stars controlled by arm number, end blocks, and pH/pressure induced aggregation, (2) monolayer polymer-metal nanocomposites by in-situ nanoparticle growth at confined interfaces, (3) on-demand control of exponentially or linearly grown heterogeneous stratified multilayers from self-diffusive pH-sensitive star polyelectrolyte nanogels, (4) core/shell umimicelle based microcapsules with a fractal nanoporous multidomain shell morphology, and (5) preferential binding and ordering of Janus-like unimicelles on chemically heterogeneous graphene oxide surfaces for biphasic hybrid assembly. The advanced branched molecular design coupled with stimuli responsive conformational and compositional behavior presents an opportunity to control the lateral diffusion and phase segregation of branched compact supermolecules on the surface resulting in the generation of well-controllable monolayers with tunable ordering and complex morphology, as well as to tailor their stratified layered nanostructures with switchable morphological heterogeneity and multicompartmental architectures. These surface-driven star polymer supramolecular assemblies and interfaces will enable the design of multifunctional nanofilms as hierarchical responsive polymer materials.

<p>Many archaeologists have been intrigued by how often symbolic houses of varying forms are used on the burialgrounds of the Scandinavian Bronze Age. Some scholars even claim that to deal with the dead did not mean to set them apart from the world of the living during this period. Since several examples show that there seem to be an active connection between the ship-setting and different types of symbolic houses, this study seek to demonstrate and interpret how the ideology behind these symbols vary between three regionally different Swedish areas: Halland, Småland and Gotland. The purpose is to show that the way chosen to shape the symbols materially not only had fundamental impact on the organization of the burialground itself, but also on how the surrounding world came to comprenhend and use them. This study suggests that even though the special shapes of the graves and the gravefield itself can carry meaning, the materialization of the monuments can be interpreted as incorporated in a practice of remembrance in where the individual shaping of the grave most probably formed part of a greater story.</p>

Στην παρούσα διατριβή διερευνήθηκε πειραματικά, η συμπεριφορά διατάξεων ενίσχυσης πλακοδοκών Οπλισμένου Σκυροδέματος, σε τέμνουσα, που αποτελούνται από το συνδυασμό τρίπλευρων μανδυών από Ινοπλισμένα Πολυμερή και αγκυρίων ινών. Πρόκειται για διατάξεις ενίσχυσης που λόγω της παρουσίας των αγκυρίων, καλούνται να υπερκεράσουν τις αδυναμίες της τεχνικής των «ανοικτών» μανδυών, δηλαδή της συνήθους τεχνικής ενίσχυσης πλακοδοκών σε τέμνουσα. Οι αδυναμίες της εν λόγω τεχνικής, οφείλονται στην ανεπαρκή αγκύρωση των άκρων του μανδύα. Η πειραματική διερεύνηση της συμπεριφοράς τέτοιων διατάξεων ενίσχυσης, έγινε με εφαρμογή τους σε τέσσερα δοκίμια πλακοδοκών Οπλισμένου Σκυροδέματος, και συγκρίθηκε με τη συμπεριφορά ενός δοκιμίου αναφοράς που δεν έφερε καμία διάταξη ενίσχυσης, καθώς και με τη συμπεριφορά ενός δοκιμίου ενισχυμένου μόνο με τρίπλευρο «ανοικτό» μανδύα ΙΟΠ, απουσία αγκυρίων. Όλα τα δοκίμια, υποβλήθηκαν σε μονοτονική φόρτιση μέσω συγκεντρωμένου φορτίου με φορά ώστε να προκαλείται θλίψη στο άνω πέλμα της δοκού, δηλαδή στην πλάκα, και οι συνθήκες στήριξης ήταν τέτοιες που να προσομοιώνουν αμφιέρειστη δοκό. Τα πρώτα Κεφάλαια της διατριβής αποτελούνται από την εισαγωγή, τη βιβλιογραφική ανασκόπηση και την περιγραφή της πειραματικής διαδικασίας. Στα επόμενα Κεφάλαια, πέραν της παρουσίασης των πειραματικών αποτελεσμάτων, επιχειρείται ο προσδιορισμός της αποδοτικότητας με παράλληλη προσέγγιση της συμπεριφοράς των διατάξεων ενίσχυσης με έμφαση στον τρόπο με τον οποίον τα αγκύρια την επηρεάζουν. Στο τελευταίο Κεφάλαιο παρουσιάζεται ο κεντρικός άξονας της διατριβής περιλαμβάνοντας και τη σύνοψη των συμπερασμάτων. / In the present thesis, the effectiveness of shear strengthening schemes for T-Shaped RC beams, consisting of FRP U-Jackets and FRP anchors, was experimentally investigated. For this purpose, six full-scale of T-Shaped RC beams were produced. One specimen served as reference (unstrengthened) beam, whereas the remaining five received FRP U-jackets; out of the latter FRP anchors were used in four beams in order to enhance the effectiveness of the strengthening schemes, whereas no anchoring system was applied to the fifth beam. All specimens were tested under monotonic loading causing compression to the wide part of the section. The first chapter of this dissertation discusses the necessity of strengthening beams in shear and introduce the objective of the study. A relatively extended literature overview about shear strengthening with externally bonded reinforcement is included in the second chapter. The purpose of the third chapter is to describe the way the specimens were designed and constructed. The strengthening procedure, the experimental setup and the materials’ properties are also included in this chapter. The test results are presented and discussed in the fourth chapter. In the fifth chapter calculations regarding the effectiveness of the strengthening schemes are presented, along with an attempt to understand their general behavior while emphasizing on the way the FRP anchors affect it. The final chapter includes the general conclusions of the present study.