Connected array antennas : analysis and design

Atom lithography is a technique to structure layers of atoms during deposition, using interactions of near-resonant light fields with neutral atoms. The basic scheme uses a standing wave light field, aligned just above a substrate, while a beam of atoms impinges perpendicularly on the standing wave light field. The interaction of the light field and the atoms focuses the atoms towards the crests or troughs of the standing wave intensity, dependent on the tuning of the light field. The focused atoms are subsequently deposited on the substrate, resulting in an array of lines, whose periodicity is determined by the wavelength of the light field. The standing wave light field can therefore be seen as an array of lenses, focusing the atom beam into an array of lines. The first experiments on atom lithography were performed in the 1990s with sodium and chromium. In this thesis experiments with iron are described, which is a magnetic element and thus allows for the creation of magnetic nanostructures. To focus atom beams into structures using atom lithography, well-colimated atom beams are required. The most common technique to create collimated atom beams is transverse laser cooling, but iron has no closed optical transition suitable for laser cooling. Fortunately Smeets and Te Sligte found that even then atom lithography of iron is possible. If the standing wave light field is considered to be an array of lenses, the focusing of the atom beam on a single lens is determined by the local collimation of the atom beam at that position. This local collimation is determined by the geometry of the beam source and the distance of the beam source to the standing wave lens. Using a small beam source (e.g. 1 mm diameter) positioned far from the standing wave (e.g. 1 m), the geometrically collimated atom beam is suitable for atom lithography. Chapter 3 shows what the implications of geometric collimation are on the structure formation in atom lithography. The geometric effects that locally collimate the atom beam on the sample also introduce local offset angles of the atom beam with respect to the focusing light field. Structure formation has been observed with lines of up to 7 nm high on a background layer of 15 nm average height, over areas of up to 400 µm × 6 mm. This indicates that the offset angles can vary over an 8 mrad range, which is more than an order of magnitude larger than the local angle of collimation. The offset angle influence the local geometry of the deposited structures: an increasing offset angle decreases the local line height, increases the width and creates a skewness in the local line shape. The local geometry of the lines has been modelled with a Monte Carlo particle tracking model and the results were compared to experiments. It was found that the highest and narrowest lines suffer from significant broadening due to surface diffusion in experiments, limiting the achievable structure width of iron on SiOx samples to about 80 nm. We have also found that in atom lithography without laser cooling, each standing wave lens is effectively imaging the source geometry onto the substrate. We therefore propose using structured atom beam sources to image more complex patterns on sub-wavelength scales in a parallel way. The reason to use iron in atom lithography, is the option to create magnetic nanostructures. However, in previous experiments no clear magnetic signature of the atom lithographic structuring of iron was found. Therefore in Chapter 4 firstly the magnetic properties of unstructured layers of iron (Fe), nickel (Ni) and FexNi1-x are investigated. These layers are all ferromagnetic, but with a reduced magnetic moment compared to bulk values due to contaminations and crystal growth effects. As a reference for periodic atom lithography structures, periodic line structures are created with interference lithography in a polymer layer and onto these structures thin layers of FexNi1-x are shadow deposited, thereby creating a layer periodically modulated in both height and elemental composition. This periodic modulation in composition has been observed with SEM-EDX on sub-micron scales. The structures showed a clear magnetic anisotropy with an easy axis along the direction of the lines, in accordance with expectations. In Chapter 5, the magnetic properties of atom lithographic iron line structures are presented. Using MOKE microscopy, direct comparison of structured and unstructured parts of a sample is possible, which allows for the observation of clear magnetic signatures due to the atom lithographic structuring. In layers of an average thickness of about 15 nm, no anisotropy is induced by the line structures, while a magnetic easy axis along the direction of the lines is expected. The line structures introduce an isotropic increase in the coercivity of the layers, indicating that the line structures can be considered as isotropic corrugations instead of directional line structures. For layers of 30 nm average thickness and thus higher line structures, a clear magnetic anisotropy is observed for the highest line structures. This anisotropy can be seen as a magnetic easy axis along the direction of the lines, as expected for line structures. However, we also observe a sharp increase in coercivity for applied fields perpendicular to the lines. This phenomenon is intriguing and may be explained by a pinning of head-to-head domain walls along the direction of the lines. In Chapter 5, we also report on the first results of co-deposition of FexNi1-x, where the Fe is structured into lines using atom lithography, while the Ni is deposited uniformly, thereby creating an alloy of modulating composition. Magnetic analysis of these structures indicates that these structures are anisotropic, both the coercivity and the shape of domain walls is dependent on the angle of the applied field relative to the line structures. Finally in Chapter 6, we investigate the possibilities to focus a thermal beam of atoms into a single 100 nm spot using light fields, thereby creating a nanopencil suitable for deposition of nanostructures. A Monte Carlo particle tracking program was developed to model the all optical focusing or funneling of 10 µm sized atom beams to a 100 nm spot. This model included effects of initial beam divergence, magnetic substructure, laser cooling, and spontaneous as well as stimulated diffusion and it was applied to a number of promising light field configurations. The best results obtained for experimentally realistic settings are a beam focused to a full width at half maximum of FWHM = 0.55 µm in a blue detuned hollow beam where atoms are focused towards the dark center, or a FWHM = 0.31 µm in a red detuned axicon light field, where atoms are focused towards the maximum intensity at the heart line. However, in the latter case the focused beam has a flux only 25 times larger than the background flux, which is unpractical for applications. The limiting factors of all schemes are heating due to stimulated diffusion and the limited interaction time available for a thermal beam of atoms. A nanopencil could be possible if it were based on the focussing of a slow and / or monochromatic atom beam, but this would seriously complicate the practical application of such a device.

Multi-alkali photocathode in super generation image intensifier is different from previous multi-alkali photocathode between the production processes,so the photoelectric emission characteristics are different from previous multi-alkali photocathode.In this paper,through the measurement of multi-alkali photocathode spectral reflectivity and transmissivity,according to the law of conservation of energy,cathode spectral absorption rate was obtained.Spectral absorption rate indicates that,only when the photon greater than 1.333 eV,cathode absorption rates began to increase quickly.The cathode spectral absorption shows that cathode will not absorb any photons if light incident photon is less than the absorption limit,i.e.933 nm wave absorption limit.In the cathode surface electron affinity further reduced circumstances,cathode photoemission long wave theory threshold is determined by long-wave absorption limit.In the electronic transition process after absorption of a photon,transition energies increase less than the absorption of the incident photon energy,i.e.the presence of an energy loss.The higher of a photon is,the higher electronic transition level is,the more loss is.At the same time,the higher of a photon is;the higher-energy level transition electron,the lower electronic transition probability is.Photocathode quantum efficiency is determined by the absorption rate,the transition probability and transition level,energy loss of diffusion process and other factors,thus photocathode quantum efficiency is in the presence of long wave threshold and shortwave threshold also.Photocathode quantum efficiency in 587 nm reaches the maximum value,after that decreases with the photon increases,when 3.6 eV,the quantum efficiency is reduced to zero.Cathode in photon of 3.6 eV the absorption coefficient is still high,but due to the electronic transition probability is low,while the electron diffusion process of loss is big,thus in spite of cathode on lower wavelength has high absorption coefficient,but the quantum efficiency is still low.Therefore on shortwave,cathode absorbed shortwave photon is converted into a photoconductive,lattice vibration and other forms of energy;the photoelectric emission utilization rate is very low.

The preparation (aqueous chemistry and the thermal activation of polyoxometalates) and the structures of promoted molybdenum oxide catalysts are investigated under the condition of selective propene oxidation by in situ Raman spectroscopy. The influences of V and/or Wpromoters on the structures of mixed MoVW oxides and their catalytic properties are investigated by XRD, TEM, SEM, in situ Raman spectroscopy and TPRS. V addition causes high propene conversions and the formation of an oxide with Mo5O14 structure is observed. Minor amounts of W in the molybdenum oxides matrix inhibit structural reorganisation processes which is explained by preferred octahedral coordination of the redox stable W. The combined XRD, TEM and Raman spectroscopic identification of the oxide of Mo5O14 structure points to its relevant role for the selective propene oxidation. A resonance Raman effect is proven to be operative in oxygen defective molybdenum oxides. For an excitation wavelength of 632 nm (1.96 eV), the observed Raman cross section varies as a function of the degree of reduction of five different MoO3 x samples. A model of the electronic transitions in MoO3 x based on crystal field theory explains the electronic transitions observed by DR-UV/VIS spectroscopy. The observed resonant Raman scattering is coupled to the IVCT transition at about 2 eV arising from oxygen vacancies present in the materials. Due to the local nature of the absorption process, the developed model is valid for intermediate oxides too. Resonant Raman scattering was proven for Mo4O11 and MoO2 too. Hence, the experimentally observed Raman intensity bears information about the degree of reduction of the molybdenum oxide. In situ Raman spectroscopy of MoO3 x catalysts during propene partial oxidation indicates that the propene conversions and the selectivities are a function of the degree of reduction of the catalyst. It is attempted to control the spatial elemental distribution within the polyoxometalate catalyst precursor by the formation of molecularly defined species in solution by addition of acetate, oxalate or tartrate. Due to the low stability of the acetate complexes, the addition of acetate only leads to minor amounts of monomeric species beside mixed and pure polyoxometalates. The formation of stable monomeric oxometalate oxalate and tartrate complexes is observed, which are expected to lead to the formation of a catalyst precursor with a homogeneous elemental distribution.

The aim of this paper was to examine the continuous and discontinuous contact problems between the functionally graded (FG) layer pressed with a uniformly distributed load and homogeneous half plane using an analytical method and FEM. The FG layer is made of non-homogeneous material with an isotropic stress–strain law with exponentially varying properties. It is assumed that the contact at the FG layer-half plane interface is frictionless, and only the normal tractions can be transmitted along the contacted regions. The body force of the FG layer is considered in the study. The FG layer was positioned on the homogeneous half plane without any bonds. Thus, if the external load was smaller than a certain critical value, the contact between the FG layer and half plane would be continuous. However, when the external load exceeded the critical value, there was a separation between the FG layer and half plane on the finite region, as discontinuous contact. Therefore, there have been some steps taken in this study. Firstly, an analytical solution for continuous and discontinuous contact cases of the problem has been realized using the theory of elasticity and Fourier integral transform techniques. Then, the problem modeled and twodimensional analysis was carried out by using ANSYS package program based on FEM. Numerical results for initial separation distance and contact stress distributions between the FG layer and homogeneous half plane for continuous contact case; the start and end points of separation and contact stress distributions between the FG layer and homogeneous half plane for discontinuous contact case were provided for various dimensionless quantities including material inhomogeneity, distributed load width, the shear module ratio and load factor for both methods. The results obtained using FEM were compared with the results found using analytical formulation. It was found that the results obtained from analytical formulation were in perfect agreement with the FEM study.

The nucleation and initial growth of diamond on Si(100) by biased hot filament chemical vapor deposition have been studied by scanning electron microscopy,Raman spectra,infrared absorption spectra and X-ray photoelectron spectra.After bias pretreated for 15min at -300V and 100mA,the nucleation density was found to be over 1010cm-2 on mirror-polished Si and was inhomogeneous,which can be divided into three regions on Si surface:A,cones at the edges;B,nanocrystalline diamond at the transition region between the edge and the centre;and C,SiC layers at the centre.The films with defects,textured films,and big discrete grains of diamond were formed at A,B,C regions respectively after 4h growth without bias.The nucleation enhancement by substrate negative bias is believed to be a combination effect of the ion bombardment and emission electron.The non-uniformity of ion distribution led to an uneven nucleation on the Si substrate surface.

Die Untersuchung der Ähnlichkeiten zwischen der mikroskopischen und makroskopischen
\nGrößenordnung ist Teil dieser Arbeit, die sich in der Forschungsfrage
\nwiderspiegelt: Was können wir über die mikroskopische Skala durch Untersuchung
\nder Makroskala erfahren? Untersuchungen der Umgebung, in der das
\nSelbst-assembly stattfindet, und das Selbst-assembly an sich helfen diese Frage zu
\nbeantworten.
\nWir imitierten die Mikroskala und identifizierten mehrere analoge Parameter.
\nAnstelle von Hitze verwenden wir Turbulenz, statt mikroskopisch kleine Partikel
\nkommen zentimetergroße Partikel zum Einsatz. Der Schwerkraft wurde durch
\neinen nach oben gerichteten Wasserstrom entgegengewirkt, da ihr Einfluss auf
\nmakroskopische Partikel beträchtlich ist. Auf mikroskopische Partikel hat sie dagegen
\nnur einen geringen Einfluss. Auf die gleiche Art und Weise hat Wärme einen
\ngroßen Einfluss auf die mikroskopische Skala, aber einen geringen Einfluss auf
\ndie makroskopische Partikel. Die Turbulenz erwies sich als geeignetes Analogon
\nfür Wärme und wurde wie im mikroskopischen Maßstab modelliert. Dabei kamen
\nthermodynamische Konzepte wie Brownsche Bewegung, Diffusion, Kinetik und
\ndie Einstein-Relation zum Einsatz. Diese Konzepte erwiesen sich auch im makroskopischen
\nMaßstab als geeignet.
\nDie Teilchengeschwindigkeit ist Maxwell-Boltzmann verteilt und die durchschnittliche
\nquadratische Verschiebung ist in Übereinstimmung mit einer begrenzten
\nZufallsverschiebung. Der Diffusionskoeffizient und die Geschwindigkeit sind
\nunabhängig von der Partikelgröße. Dies führt zu der Interpretation, dass die
\nBewegung einer einzelnen zentimetergroßen Kugel der Bewegung eines mikroskopischen
\nTeilchens a¨hnelt, indem sie eine Zufallsverschiebung und eine Brownsche
\nBewegung ausführt. Um mikro- oder nanoskopische Partikel sichtbar zu machen,
\nwerden häufig Rasterelektronen- oder Lichtmikroskopie verwendet. Anstelle von
\nMikroskopen verwendeten wir Videokameras, um die Experimente mit zentimetergroßen
\nPartikeln aufzuzeichnen. Eine Schwimmbadpumpe und asymmetrische Einströmung
\n(eines von vier Einlassventilen ist immer geschlossen) wurden eingesetzt,
\num Turbulenzen und asymmetrische Strömung zu erzeugen. Dieser asymmetrische
\nZufluss kann große makroskopische Wirbel verursachen, die die Eingangswärme
\nim Mikromaßstab darstellen. Im mikroskopischen Fall ist die Brownsche Bewegung
\n90
\nZusammenfassung 91
\nder Teilchen das Ergebnis derAusbreitung vonWärme, die von ihrer Quelle ausgeht,
\nwährend im makroskopischen Maßstab die von der Asymmetrie der Strömung herrührende
\nVermehrung die Brownsche Bewegung großer Teilchen verursacht. Trotz
\ndieser Ähnlichkeiten zwischen Wärme und Turbulenz variieren die Werte für die
\nPerturbationsenergie erheblich, je nachdem, ob sie über eine Einzelkugel-Diffusion
\n(Einstein-Beziehung) und Geschwindigkeit (kinetische Energie) oder über Wechselwirkungen
\nzwischen zwei magnetische Kugeln über die Entfernung bestimmt
\nwurden. Der letztere Fall ist um eine Größenordnung niedriger, etwa 6.5 μJ verglichen
\nmit 80 μJ. Dies legt nahe, dass die Wärme- oder Turbulenzenergie-Spektren
\nin Bezug auf ihreWirkung auf die Partikel unterschiedlich sein können. Es besteht
\neine gerichtete Abhängigkeit von Teilchengeschwindigkeit, Diffusion und Perturbationsenergie.
\nDie horizontalen Dimensionen sind ähnlich, aber die vertikale
\nKomponente zeigt eine stärkere Abhängigkeit in Bezug auf Strömungsasymmetrie
\nund Turbulenz. Der Richtungsabhängigkeit kann voraussichtlich über zukünftige
\ntechnische Anpassungen entgegengewirkt werden. Die gerichtete Abhängigkeit
\nkann auch als Temperaturgradient interpretiert werden.
\nDas Self-assembly wurde durch Strukturbildung mehrerer magnetischer Kugeln
\noder eines Dodekaheders aus zwölf heptagonalen magnetischen Plättchen durch
\nsystematische Variation von Turbulenz und Asymmetrie untersucht. Die multiplen
\nmagnetischen Kugeln bilden Linien und Ringe, und ihr Auftreten entsprach der
\nTheorie, jedoch wichen die absoluten Energien der Strukturen von der Theorie ab.
\nFür Experimente mit zunehmender Anzahl von Kugeln stellen vier Kugeln einen
\nÜbergang zwischen Linien und Ringen dar. Das System erwies sich als geeignet
\num die minimale Energiestruktur anzustreben, was wiederum zeigt, dass sich unser
\nmakroskopisches System ähnlich wie die Mikroskala verhält. Die Turbulenz wirkte
\nähnlich wie dieWärme, da fast nur einzelne Teilchen bei hoher Turbulenz beobachtet
\nwurden, während sich Linien und Ringe, bei abnehmender Turbulenz bildeten,
\nwas einem Phasenübergang zwischen einer Flüssigkeit und einem Feststoff oder
\neinem Gas und einer Flüssigkeit ähnelt.
\nDas Self-assembly von zwölf Zentimeter großen pentagonalen Plättchen
\nzeigte das gleiche Energieminimierungsverhalten wie die Kugelstrukturen. Ein
\nvollständiges Self-assembly des Dodekaeders wurde nicht erreicht. Vorherrschend
\nwaren intermediäre Strukturen mit maximalen Kontakten zwischen jedem Partikel
\n(Trimer und Tetramer etc.), was der minimalen Energiestruktur entspricht. Auch in
\ndiesem komplexeren Fall verhält sich das System ähnlich wie im Mikromaßstab.
\nDie beiden Beispiele des Self-assembly repräsentieren zum einen die Bildung
\neinfacher Strukturen (Ringe und Linien) und zum anderen einen komplexeren Fall
\ndes Self-assembly (ein hohles Dodekaeder). Das letztere Beispiel kann als Selfassembly
\neines geometrischen Konstrukts oder als Modell f ür das Selbst-assembly
\neines sphärischen Virus interpretiert werden. Dies unterstreicht das Potenzial des
\nmakroskopischen Self-assembly; es kann bei der Untersuchung von allgemein
\nweitgehend größenunabhängigen Problemen oder als analoge Darstellung bei der
\nUntersuchung von natürlich vorkommenden Phänomenen eingesetzt werden.

An expression is derived for the proportion of quadrilaterals among the polygons formed by random lines in the plane. Its value is 0.381 466….

Graphs are commonly represented as points in space connected by lines. The points in space are the vertices of the graph, and the lines joining them are the edges of the graph. A general definition of a graph is considered here, where multiple edges are allowed between two vertices and an edge is permitted to connect a vertex to itself. It is assumed that graphs are connected, i.e., any vertex in the graph is reachable from another distinct vertex either directly through an edge connecting them or by a path consisting of intermediate vertices and connecting edges. Under this visual representation, graphs can be drawn on various surfaces. The focus of my research is restricted to a class of surfaces that are characterized as compact connected orientable 2-manifolds. The drawings of graphs on surfaces that are of primary interest follow certain prescribed rules. These are called 2-cellular graph embeddings, or simply embeddings. A well-known closed formula makes it easy to enumerate the total number of 2-cellular embeddings for a given graph over all surfaces. A much harder task is to give a surface-wise breakdown of this number as a sequence of numbers that count the number of 2-cellular embeddings of a graph for each orientable surface. This sequence of numbers for a graph is known as the genus distribution of a graph. Prior research on genus distributions of graphs has primarily focused on making calculations of genus distributions for specific families of graphs. These families of graphs have often been contrived, and the methods used for finding their genus distributions have not been general enough to extend to other graph families. The research I have undertaken aims at developing and using a general method that frames the problem of calculating genus distributions of large graphs in terms of a partitioning of the genus distributions of smaller graphs. To this end, I use various operations such as edge-amalgamation , self-edge-amalgamation, and vertex-amalgamation to construct large graphs out of smaller graphs, by coupling their vertices and edges together in certain consistent ways. This method assumes that the partitioned genus distribution of the smaller graphs is known or is easily calculable by computer, for instance, by using the famous Heffter-Edmonds algorithm. As an outcome of the techniques used, I obtain general recurrences and closed-formulas that give genus distributions for infinitely many recursively specifiable graph families. I also give an easily understood method for finding non-trivial examples of distinct graphs having the same genus distribution. In addition to this, I describe an algorithm that computes the genus distributions for a family of graphs known as the 4-regular outerplanar graphs.

Electric energy has been transmiting from power station to end user with transmission and distribution lines.Lightning strokes are problems that occure in transmission and distribution lines and make them fault when theelectric energy were transmited. Surge Diverter or Lightning Arrester has been installing to reduce these faults.In this paper the simulation of lightning stroke and lightning arrester performance on distribution lines 20 kVwere done using EMTP (Electromagnetic Transient Program). Some parameters such us impuls voltage andincreasing voltage on distribution line was inverstigated. As case study in this simulation, Mojosongo 1 mainfeeder 20 kV three phase lines were used.The simulation results show that the lightning stroke 20 kA in By1-61-61E-84-9I on S phase at 0,1 ms, makevoltage on S phase was increased about 1,3054 MV. For R phase and T phase will increase of induced voltagewere 0.79539 MV and 0.80484 MV. We also show the performance of MOV Arrester (Metal Oxide Varistor) inovercoming lightning stroke trouble, where arrester can decrease voltage up to 15.198 kV on S phase, while atR phase and T phase arrester can decrease voltage up to 11.375 kV and 13.616 kV.

Electrical Discharge Machining (EDM) is a well-known machining technique since more than fifty years. Its principle is to use the eroding effect on the electrodes of successive electric spark discharges created in a dielectric liquid. EDM is nowadays widely-used in a large number of industrial areas. Nevertheless, few studies have been done on the discharge itself and on the plasma created during this process. Further improvements of EDM, especially for micro-machining, require a better control and understanding of the discharge and of its interaction with the electrodes. In this work, the different phases of the EDM process and the properties of the EDM plasma have been systematically investigated with electrical measurements, with imaging and with time- and spatially-resolved optical emission spectroscopy. The pre-breakdown phase in water is characterized by the generation of numerous small hydrogen bubbles, created by electrolysis. Since streamers propagate more easily in a gaseous medium, these bubbles can facilitate the breakdown process. In oil, no bubbles are observed. Therefore, the breakdown mechanism in oil could be rather enhanced by particles present in the electrode gap. Fast pulses of current and light are simultaneously measured during the pre-breakdown. These pulses are characteristic of the propagation of streamers in the dielectric liquid. The pre-breakdown duration is not constant for given discharge parameters, but distributed following a Weibull distribution. This shows that the breakdown is of stochastic nature. After the breakdown, the plasma develops very rapidly ( 2·1018 cm-3 during the first microsecond). Then it decreases with time, remaining nevertheless above 1016 cm-3 after 50 μs. During the whole discharge, the density is slightly higher in the plasma center. The EDM plasma has such a high density because it is formed from a liquid, and because it is constantly submitted to the pressure imposed by the surrounding liquid. This extreme density produces spectra with strongly-broadened spectral lines, especially the Hα line, and with an important continuum. During the first microsecond when the density is at its maximum, spectral lines are so broadened that they are all merged into a continuum. The low temperature and the high density of the EDM plasma make it weakly non-ideal. Its typical coupling parameter Γ is indeed around 0.3, reaching 0.45 during the first microsecond. In this plasma, the Coulomb interactions between the charged particles are thus of the same order as the mean thermal energy of the particles, which produces coupling phenomena. Spectroscopic results confirm the non-ideality of the EDM plasma. The strong broadening and shift of the Hα line and its asymmetric shape and complex structure, the absence of the Hβ line, and the merging of spectral lines are typical of nonideal plasmas. The EDM plasma has thus extreme physical properties, and the physics involved is astonishingly complex.

Load growth, high penetration of distributed generators (DG) and energy storage systems (ESSs) have caused different challenges for the distribution networks (DNs) such as congestion in their lines. This paper assesses the impact of congestion on the operational cost of the multi microgrid (MMG) based DN firstly. Then, a security constrained energy management system (SC-EMS) for the MMG system is proposed by considering the effect of the network's load flow constraints on the scheduling of that. Obviously, adding extra constraints to the optimization problem of the MMG system leads to increment in the operational cost. In order to resolve this problem, tie lines between MGs are modelled. In fact, in the proposed model, MGs can trade energy not only with the DN, but also with other MGs. Moreover, it is evaluated that considering the MGs as an integrated unit decreases the overall operational costs. Simulations on a modified IEEE 33-bus test system with multiple MGs are performed in GAMS environment. As expected, the gained results demonstrate the increment in the operational costs of the DN and the MGs when the contingencies occur in the network's lines. On the other hand, taking the tie lines into account as a recommended solution leads to a decrement in the operational cost of the MMG system.

Long term supporting schemes for photovoltaic (PV) system installation have led to accommodating large numbers of PV systems within load pockets in distribution grids. High penetrations of PV systems can cause new technical challenges, such as voltage rise due to reverse power flow during light load and high PV generation conditions. Therefore, new strategies are required to address the associated challenges. Moreover, due to these changes in distribution grids, a different response behavior of the distribution grid on the transmission side can be expected. Hence, a new equivalent model of distribution grids with high penetration of PV systems is needed to be addressed for future power system studies. The thesis contributions lie in three parts. The first part of the thesis copes with the PV modelling. A non-proprietary PV model of a three-phase, single stage PV system is developed in PSCAD/EMTDC and PowerFactory. Three different reactive power regulation strategies are incorporated into the models and their behavior are investigated in both simulation platforms using a distribution system with PV systems. In the second part of the thesis, the voltage rise problem is remedied by use of reactive power. On the other hand, considering large numbers of PV systems in grids, unnecessary reactive power consumption by PV systems first increases total line losses, and second it may also jeopardize the stability of the network in the case of contingencies in conventional power plants, which supply reactive power. Thus, this thesis investigates and develops the novel schemes to reduce reactive power flows while still keeping voltage within designated limits via three different approaches: 1. decentralized voltage control to the pre-defined set-points 2. developing a coordinated active power dependent (APD) voltage regulation Q(P) using local signals 3. developing a multi-objective coordinated droop-based voltage (DBV) regulation Q(V) using local signals In the third part of the thesis, furthermore, a gray-box load modeling is used to develop a new static equivalent model of a complex distribution grid with large numbers of PV systems embedded with voltage support schemes. In the proposed model, variations of voltage at the connection point simulate variations of the model’s active and reactive power. This model can simply be integrated into load-flow programs and replace the complex distribution grid, while still keeping the overall accuracy high. The thesis results, in conclusion, demonstrate: i) using rms-based simulations in PowerFactory can provide us with quite similar results using the time domain instantaneous values in PSCAD platform; ii) decentralized voltage control to specific setpoints through the PV systems in the distribution grid is fundamentally impossible due to the high level voltage control interaction and directionality among the PV systems; iii) the proposed APD method can regulate the voltage under the steady-state voltage limit and consume less total reactive power in contrast to the standard characteristic Cosf (P) proposed by German Grid Codes; iv) the proposed optimized DBV method can directly address voltage and successfully regulate it to the upper steady-state voltage limit by causing minimum reactive power consumption as well as line losses; v) it is beneficial to address PV systems as a separate entity in the equivalencing of distribution grids with high density of PV systems.

David Lean's epic movie Lawrence of Arabia has enchanted generations of audience ever since 1962 for many of its accomplishments, ranging from its memorable cut, the matchstick, to philosophical lines such as ”Nothing is written” or ”[The desert] is clean here.” When they are crossing the Nefud Desert, God's anvil, the camel-riding Lawrence, is cautioned by Ali not to be ”drifting.” The then ”thinking” Lawrence is like an unlocatable nomad on Deleuze's virtual plane of immanence. His living identity is not something bound in well-defined categories; instead, it inheres as a pure, yet-to-be-actualized singular event engulfed in an indefinite between-time. Lawrence's pure becomings, irrespective of habit and memory, are being played out in incessant repetitions like a dice throw, only to arrive at a different ”broken, dissolved self.”This paper proposes to read Lawrence of Arabia in the light of Deleuzian concepts of difference and repetition. It examines the relationship between identity or doxa of habitual configurations in the realms of reactive representations on the one hand, and, on the other, self-losing identity that is constantly in the making, constituted by a singular flow of percepts and affects in the active, creative and pre-representational realms. With detailed study of Lean's cinematic text/ure, this paper will address the problem why Lawrence deviates from his Englishness to becoming Arab.

PRIMARY CILIA MECHANOTRANSDUCTION AND MICROTUBULE STABILITY IN MECHANICALLY STRETCHED LUNG ADENOCARCINOMA CELLS By Monika Rassi Radhika, B.E. A Thesis submitted in partial fulfillment of the requirements for the degree of Masters of Science in Biomedical Engineering at Virginia Commonwealth University. Virginia Commonwealth University, 2015 Major Director: Rebecca L. Heise, Ph.D. Assistant Professor, Biomedical Engineering The objective of this study is to investigate the role of microtubule based organelle, the primary cilia in lung adenocarcinoma by i) Quantifying the presence of primary cilia in several Non Small Cell Lung Cancer (NSCLC) cell lines in response to mechanical stimuli, ii) Attempting to determine the role of primary cilia in cell migration, iii) Investigating the effects of Paclitaxel(Taxol) resistance in lung cancer cells, iv) Analyzing the response of lung cancer cells to Smoothened Inhibitors and v) Determining the effects of Transforming Growth Factor Beta-1(TGF-β1) induced Epithelial to Mesenchymal Transition(EMT) in lung cancer cells. To ascertain the effects of primary cilia in the hall marks of tumor progression, several experiments involved prohibition of primary cilia formation by silencing IFT88, the gene responsible using small interfering RNA. Three out of the five cell lines tested, showed increased expression of primary cilia under mechanical stretch. IFT88 inhibition of H460 cells decreased their migration rate to the injury site under stretch conditions. Smoothened (SMO) Inhibitors decreased proliferation and migration rates in human lung adenocarcinoma cell lines (A549luc) similar to the effects observed in IFT88 silenced cells. IFT88 silenced A549luc cells showed a partial reversal of TGF-beta1 induced up-regulation of a mesenchymal marker. These results indicate that primary cilia play a role in the progression and metastasis of lung cancer by aiding the adhesion, proliferation, migration and EMT of lung cancer cells.

In this study, two-dimensional finite element modeling was used to study the simultaneous effect of the cell shape and regular cell distribution on the anisotropy of the elastic properties of 316L stainless steel foam. In this way, the uniaxial compressive stress-strain curve was predicted using a geometric model and fully solid 316L stainless steel. The results showed that the elastic tangent and the yield strength increase significantly if the direction of the loading is parallel to the major cell dimension. Besides, the regular cell distribution affects the above properties, and the sharp drop in the mechanical properties is observed when the maximum shear stress plane is parallel with the plane including higher cell density. In addition, the finite element modeling showed that the elastic properties of porous 316L stainless steel are anisotropic and the optimum conditions depend entirely on the shape of the cells and the loading direction in the regular cell distribution foam.