Für die Menschen zählen Gewitter mit Donner und Blitz zu den ältesten bekannten Phänomenen der Natur. Die Tatsache, dass Blitze dennoch bis heute nicht abschließend erforscht sind, liegt in dem äußerst komplexen, schnellen und stochastischen Verhalten der Blitzentladung begründet. Der Autor befasste sich in Rahmen dieser Arbeit u.a. mit der Entwicklung eines modernen Messsystems, durch das die Erfassung von sowohl elektrischen als auch optischen Parametern der im Nanosekundenbereich ablaufenden Prozesse der Entladungen möglich wurde. Es handelt sich um technisch anspruchsvolle Messungen von hohen Stoßspannungen und schwachen Vorentladungsströmen in einem großen Frequenzbereich. Außerdem gelang es durch eine geschickte Synchronisation, die Entladungsprozesse präzise und erstmalig in einer Fotosequenz aufzunehmen. Auf Grundlage der Messergebnisse konnte der Entladungsprozess in mehrere Phasen der Vorentladung unterteilt und beschrieben werden. Vor allem beweisen die Messergebnisse die Existenz einer kanalartigen Vorentladung, die nicht zwingend zu einem Durchschlag führt. Dieser Mechanismus, der bei langsam ansteigenden Spannungen als stabile Leaderentladung benannt und mit Thermoionisation gekennzeichnet ist, war bei Blitzstoßspannungen bisher umstritten. / The breakdown behavior of long air gaps by Lightning Voltages has been investigated and the results of a new measurement system are reported. A series of up to eight photos (made by a high-speed camera) have recorded the expansion of discharge activities during the breakdown process. The pre-discharge current and voltage have been measured as well. The modern measurement techniques have made possible the synchronization of the photos with the current and voltage measurements in nanosecond-ranges. The combination of the measured current, voltage, and photos can precisely explain the breakdown process. The experiments have been carried out with the lightning impulses up to 2.4 MV and the air gaps up to 4 m. Despite of such high voltages, the experimental system has been verified to be appropriate for measuring the pre-discharge current in mA-ranges.

This thesis seeks to examine the ways that the success of the Dutch Empire at the turn of the twentieth century was represented and celebrated in the photographic albums of Dutch sugar industrialists in Java. It aims to show how the photographic practices that developed in the colony in parallel with its industrialisation informed the ways that the colony was imagined in the metropolis and the colony. Whether social portraiture, topographic studies or depictions of industrial machinery and infrastructure, the photographs of the sugar industry were part and parcel of a topical vernacular tradition that generated distinct visual themes in the development of popular photographic genres, and which reflected the cultural hybridity and social stratification of the local sugar world. This analysis is pursued through close reading of the photographic albums of the Pietermaat-Soesman family from the Kalibagor sugar factory in Java. These albums exemplify how the family albums of sugar industrialists retained the familiarity and cult value of the family album whilst illustrating the values and attitudes of the colonial industry and society. What is more, the Pietermaat-Soesman albums underline the significance of the albums' materiality; their story is not only one of images, but also a story of objects. I specifically pay attention to the role of photographers and commercial photo studios in the formulation of the pictorial commonplace of the sugar industry. It is the collaboration between sugar industrialists and colony-based photographers that reveals the social necessity, ideological constraints, pictorial conventions and cultural idioms of colonial industry and society in the Dutch East Indies. Largely understudied in both the Dutch and Indonesian histories of photography, this material, I argue, may problematise the ideological premises of ‘colonial' photography.

Aujourd’hui nous pouvons être à un endroit du monde et réaliser des prises de vues à des centaines de kilomètres. La distance, qui jusqu’à présent se limitait à celle de la perception de notre œil, n’a aujourd’hui plus de limites, grâce aux nouvelles technologies. Cette thèse étudie la situation de l’artiste, dans le traitement du paysage, face à ces choix offerts à lui, entre l’analogique et le numérique. Ce serait la multiplicité de ce qu’offrent les technologies qui, par la main de l’artiste, permettraient de faire muter le paysage contemporain. Selon notre hypothèse, les Mutation(s) du paysage contemporain ne se joueraient pas uniquement sur une continuité temporelle, suivant l’évolution des technologies, oubliant progressivement l’analogique au profit du numérique. Il y aurait bien cet Entre qui se révèlerait être au cœur de nos questionnements. La thèse se développe en trois parties, comme une sorte de triptyque : Hors-champ, Instants, Non-lieu, en prenant appui sur notre pratique d’artiste. Partant de nos origines bretonnes, nous irons puiser dans des légendes et cultures celtes (l’Anaon, l’intersigne, etc.) qui nous entraîneront vers l’Asie (les évaporés au Japon, etc.), naviguant entre les technologies, entre le visible et l’invisible, entre le réel et le virtuel. En définitive, la mutation (au pluriel) est une et multiple à la fois. Cette figure complexe (au sens d’Edgar Morin) rappelle celle du Yi-Jin, dont sa définition suggère des mises en rapport de signes. Elle n’est pas sans proximité avec l’écriture oghamique, qui est un alphabet antique celte. Notre thèse est que l’Ogham, en connivence avec le Yi-Jin, participerait d’une nouvelle définition du paysage contemporain. / We can be in one place in the world and take pictures of places located at hundreds of kilometers away. The distance, that up to now, used to be limited to our eyes’ perception, has no more limits, thanks to new technologies. This thesis analyzes the position of the artist in the treatment of landscape in view of the choices offered between analogue and digital.This would be the multiplicity of the technological possibilities, that through the hands of the artist, allows to mutate the contemporary landscape. According to our hypothesis, the Mutation(s) of contemporary landscape, would not be based exclusively on a temporal continuity, following the technological evolution, that progressively forgets the analogue in favor of the digital. There would be this In Between that would be at the center of our questioning. The thesis develops itself in 3 parts, like a sort a tryptique: off-track - instants - out of place, based on our practice as artist. Departing from our Brittany origins, we will immerse into the Celtic legends (the “Anaon”, the “intersigne”, etc.) and cultures that will take us to Asia (the “evaporated” in Japan, etc.), shifting between the technologies, between the visible and the invisible, between the real and the virtual.In the end, the mutation (in plural) is one and many at the same time. This complex representation (in the sense of Edgar Morin) reminds that of Yi-Jin, of which his definition suggests the relationship between signs. It is not without the proximity of the Oghamic writing, that is an ancient Celtic alphabet. Our position is that the Ogham, in connection with the Yi-Jin, would be part of a new definition of the contemporary landscape.

Developments in high-performance computing instruments and advancements in the numerical algorithms combined with lattice gauge theory make it possible to simulate Quantum Chromodynamics (QCD), the theory of strongly-interacting quarks and gluons, numerically at nearly physical light-quark masses. In this work we present our results for the $D^*Dpi$ coupling constant as simulated on $32^3 imes 64$, unquenched $2+1$-flavor lattices. We estimate the coupling at the chiral limit as $g_{D^*Dpi} = 16.23 pm 1.71$, which is in good agreement with its experimental value $g^{(exp)}_{D^*Dpi} = 17.9pm0.3pm1.9$ as obtained by CLEO II Collaboration.

Aluminum alloys are having more attention due to their high specific stiffness and processing advantages. 7075 aluminum alloy is a wrought composition aluminum alloy in the Al-Zn-Mg-Cu series. Due to the significant addition of these alloying elements, 7075 has higher strength compared to all other aluminum alloys and effective precipitation hardenability characteristic. On the other hand, aluminum alloys have some drawbacks, which hinder the widespread application of them. One of the most commonly encountered defects in aluminum alloys is the hydrogen porosity. Additionally, in case of 7075, another problem is the lack of fluidity. Magnesium addition is thought to be effective in compensating this deficiency. Accordingly, in this study, die cast 7075 aluminum alloy samples with hydrogen porosity and additional magnesium content were investigated. The aim was to determine the relationship between hydrogen content and hydrogen porosity, and the effects of hydrogen porosity, additional magnesium and T6 heat treatment on ultimate tensile and flexural strength properties of pressure die cast 7075 aluminum alloy. 7075 aluminum alloy returns were supplied from a local pressure die casting company. After spectral analysis, pressure die casting was conducted at two stages. In the first stage, 7075 aluminum alloy with an increase in magnesium concentration was melted and secondly 7075 aluminum alloy was cast directly without any alloying addition. While making those castings, hydrogen content was measured continuously before each casting operation. As a final operation T6 heat treatment is carried out for certain samples. Finally, in order to accomplish our aim, mechanical and microstructural examination tests were conducted.

The emulsion target of the CHORUS detector was exposed to the wide-band neutrino beam of the CERN SPS between the years 1994 and 1997. In total about 130.000 neutrino interactions were located in the nuclear emulsion target and fully reconstructed. Detailed DATA and Monte Carlo (MC) comparisons were done in order to test reliability of the detector simulation. There is reasonable agreement between DATA and MC. The ratio of deep inelastic neutral-current (NC) to the deep inelastic (DIS) charged-current(CC) $nu_{mu}$ interactions was measured to be frac{NC_{dis}}{CC_{dis}}=0.350pm0.003$. This measurement was compared with the previous measurements. Based on three double charm decays found in NC interactions we measured the ratio of double charm cross-section in NC $nu_{mu}$ interactions to be [ frac{sigma (cbar{c}nu_mu)}{sigma_{NC}}=(3.37^{+3.06}_{-2.51}(stat.)pm 0.51(syst.))times 10^{-3}. ] One double charm decay has been observed in CC $nu_{mu}$ interactions the upper limit on associated charm production in $nu_{mu}$ CC interaction has been found to be [ frac{sigma cbar{c}mu^{-})}{sigma_{CC}}&lt / 9.69 times 10^{-4}. ] at 90% C.L.

In this study, a novel incremental ring rolling process used in production of rings with various cross sections is examined. A basic type of this process is investigated numerically, using commercial finite element programs / MSC Superform, MSC Marc. The user defined subroutines are also utilized for flexibility in modeling. The aim of modeling is to determine the material flow for geometrical analysis, strain/stress distribution for tool force analysis and residual stresses, in a cost effective way. The process has instabilities and requires large number of incremental stages to complete a full finite element simulation. The full models are reliable but costly hence the numerical studies are focused on reliable simplified models with lower computation time. Different approaches are developed: three-dimensional segment model, improved segment model, velocity coupling model. The results of these models are compared with experimentally verified full models. Numerical parameters such as mesh type, step size, convergence ratio are examined. After verification of the model different applications to of the process is developed and physical parameters affecting the process are discussed / such as the tool path .

For the anti-charmed pentaquark state with and without strangeness a QCD sum rule analysis, which is one of the nonperturbative approaches, is presented. For this purpose we employ pentaquark currents with and without strangeness, with two different current for each case. To refine the sum rules we also consider the DN continuum contribution in our analysis since this procedure is important to identify the signal of the pentaquark state. While the sum rules for most of the currents are either non-convergent or dominated by the DN continuum, the one for the non-strange pentaquark current composed of two diquarks and an antiquark, is convergent and has a structure consistent with a positive parity pentaquark state after subtracting out the DN continuum contribution. Arguments are presented on the similarity between the result of the present analysis and that based on the constituent quark models, which predict more stable pentaquark states when the antiquark is heavy.

In this thesis a search for electron type neutrino-electron scattering cross-section and Weinberg Angle measurements were performed at KS Nuclear Power Station with 200 kg CsI(Tl) scintillating crystal detector located at a distance of 28 m from the 2.9 GW reactor core giving total flux of 6:52X10^12 cm^-2s^-1 in average at the experimental site. New analysis techniques and background suppression methods were developed. In the region of 3-8 MeV a measurement of SM cross section of (1:235+-0.577) XR_SM and Weinberg Angle of 0:264 +-0.075 which is quite consistent with the SM value of 0.23120(15)were obtained. These are the best results with wold wide level sensitivities at untested low energy region by using reactor anti-neutrinos.

In this thesis, we applied Light Cone QCD sum rules (LCSR) to several problems in meson physics. Semileptonic B-&gt / eta l v decays are important to get information on Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. We calculated form factors of this decay in LCSR frame. Our results are confirmed by later studies and these similar studies had been used for enhancing result on b to u quark transition matrix element of CKM matrix by BaBar collaboration. We used LCSR method also for calculating coupling constant of radiative rho -&gt / eta photon decay since the analysis of the vector particle to pseudoscalar particle radiative decay with eta and eta&#039 / mesons in final state can provide insights to the long standing issue of the eta and eta&#039 / mixing. Our result g_{rho eta photon}=(1.4 &plusmn / 0.2) is very close to experimental value g_{ rho eta photon} = (1.42 &plusmn / 0.12). We also calculated magnetic moment of the rho meson in LCSR frame which is an important parameter since it is strongly related to internal structure of hadron. Our result 2.3 &plusmn / 0.5 in units of (e/2m_rho), is in better agreement with lattice QCD results than traditional QCD sum rules. Quark contents of light scalar mesons are still under debate and we analyzed phi -&gt / K K decays which is important for understanding the quark content of the f0 meson. Our final result is g_{phi KK} = 4.9 &plusmn / 0.8 which is in well agreement with existing experimental result g_{phi KK} = 4.8.