No description available.

Using the orbicell decomposition of the Deligne-Mumford compactification of the moduli space of Riemann surfaces studied before by the author, a chain complex based on semistable ribbon graphs is constructed which is an extension of the Konsevich’s graph homology. / En este trabajo mediante la descomposicion orbicelular de la compacticacion de Deligne-Mumford del espacio de moduli de supercies de Riemann (estudiada antes por el autor) construimos un complejo basado en grafos de cinta semiestables, lo cual constituye una extension de la homologa de grafos de Kontsevich.

We begin developing a theory of morphisms of moduli spaces of pseudoholomorphic curves and discs with Lagrangian boundary conditions as Kuranishi spaces, using a modification of the procedure of Fukaya-Oh-Ohta-Ono. As an example, we consider the total space of the line bundles O(−n) and O on P1 as toric Kähler manifolds, and we construct isomorphic Kuranishi structures on the moduli space of holomorphic discs in O(−n) on P1 with boundary on a moment map fiber Lagrangian L and on a moduli space of holomorphic discs subject to appropriate tangency conditions in O. We then deform this latter Kuranishi space and use this deformation to define a Lagrangian potential for L in O(−n), and hence a superpotential for O(−n). With some conjectural assumptions regarding scattering diagrams in P1 × P, this superpotential can then be calculated tropically analogously to a bulk-deformed potential of a Lagrangian in P1 × P1.

No description available.

Graphite is used within a reactor as a moderator and a reflector material. During fast neutron irradiation, the physical properties and dimensions of nuclear graphite are changed significantly. Graphite shrinkage could lead to disengagement of individual component and loss of core geometry; differential shrinkage in the graphite component could lead to the generation of internal stresses and component failure by cracking. The latter behaviour is complicated by the irradiation induced changes in Young's modulus and strength. These dimensional and modulus change have been associated with the irradiation-induced closure of many thousands of micro-cracks associated with the graphite crystallites due to crystal dimensional change. Closure of microcracks in nuclear graphite was simulated by external pressure (hydrostatic loading, deviatory stress and dynamic loading) and not by irradiation, whilst Young's modulus was measured to check if there was any correlation between the two mechanisms. A study of the deformation behaviour of polycrystalline graphite hydrostatically loaded up to 200MPa are reported. Gilsocarbon specimens (isotropic) and Pile Grade A (PGA) specimens are (anisotropic in nature) were investigated. Strain measurements were made in the axial and circumferential directions of cylindrical samples by using strain gauges. Dynamic Young's modulus was also investigated from the propagation velocity of an ultrasonic wave. Porosity measurements are made to determine the change in the porosity before and after deformation and also their contribution towards the compression and dilatation of graphite under pressure. Graphite crystal orientation during loading was also investigated by using XRD (X-ray diffraction) pole figures. Effective medium models were also investigated to describe the effect of porosity on graphite elastic modulus. All the graphite specimens investigated exhibited non-linear pressure- volumetric strain behaviour in both direction (axial and circumferencial). In most of the experiments, the deformation was closing porosity despite new porosity being generated. Under hydrostatic loading, PGA graphite initially stiff then it became less stiff after a few percent of volume strain and then after about ~20% volumetric strain they stiffen up again, whist Gilsocarbon showed similar behaviour at lower volumetric strain (~10-13%). Gilsocarbon was stiff than PGA; this behaviour is due to the fact that Gilsocarbon has higher density and lower porosity than PGA. During unloading, a large hysteresis was formed. The stressed grains are relieved; the initial closed pores began to reopen. It is suggested that during this stage, the volume of pore re-opening superseded the volume of pores closing, the graphite sample volume almost fully recovered. In the axial compression test, PGA perpendicular to the extrusion direction (PGA-AG) was less stiff than PGA parallel to the extrusion direction (PGA-WG); in the hydrostatic compaction test, the PGA-WG sample deformed more because it had to undergo a less complicated shape change. This is because the symmetry of their anisotropy is parallel to the symmetry of the sample. The Pole figures showed an evidence of slight crystal reorientation after hydrostatic loaded up to 200MPa. The effective medium model revealed the importance of porosity interaction in graphite during loading.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Neste trabalho, mostramos que equivalÃncia HÃlder de germes de funÃÃes analÃticas (C2, 0) → (C, 0) admite moduli contÃnuo. Mais precisamente, construimos um invariante da equivalÃncia HÃlder de tais germes que varia continuamente numa famÃlia ft : (C2, 0) → (C, 0). Para um Ãnico germe ft o invariante de ft à dado em termos dos coeficientes principais das expansÃes assintÃticas de ft ao longo dos ramos da curva polar genÃrica de ft. / In this work, we show that HÃlder equivalence of analytic functions germs (C2, 0) → (C, 0)admits continuous moduli. More precisely, we constructed an invariant of the HÃlder equivalence of such germs that varies continuously in a family ft : (C2, 0) → (C, 0). For a single germ ft the invariant of ft is given in terms of the leading coefficients of the asymptotic expansion of ft along the branches of generic polar curve of ft .

The purpose of this dissertation is to investigate the geometry of spaces of planar quadrilaterals. The topology of moduli spaces of planar quadrilaterals (the set of all distinct planar quadrilaterals with fixed side lengths) has been well-studied [5], [8], [10]. The symplectic geometry of these spaces has been studied by Kapovich and Millson [6], but the Riemannian geometry of these spaces has not been thoroughly examined. We study paths in the moduli space and the pre-moduli space. We compare intraplanar paths between points in the moduli space to extraplanar paths between those same points. We give conditions on side lengths to guarantee that intraplanar motion is shorter between some points. Direct applications of this result could be applied to motion-planning of a robot arm. We show that horizontal lifts to the pre-moduli space of paths in the moduli space can exhibit holonomy. We determine exactly which collections of side lengths allow holonomy. / Ph. D.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / VME bus has been widely accepted as an industry standard for control and process computers. The MSTI (Miniature Sensor Technology Integration) series of satellites employ a VME bus based data acquisition and control system. This system requires a ruggedized, high-speed, compact, low power and light weight data recorder for storing digital imagery from payload video cameras, as well as health and status data of the satellite. No commercial off the shelf systems were found which meet MSTI specifications. Also, a solid state device eliminates certain reliability and spacecraft pointing control problems which are encountered when using rotating (disk or tape) storage systems. The SSDR was designed to meet these requirements and it also has built-in flexibility for many general purpose applications. The electronic hardware design, which conforms to the VME bus specifications [1], can also be configured as stand-alone system. Modular memory array design allows expandability of capacity up to 320 MBytes. This paper will describe the design features of the SSDR. Performance capabilities and system implementation will be discussed. Special approaches required for application of the SSDR in space or harsh environments are also discussed.

In this thesis, we study compactifiations of ten-dimensional heterotic supergravity at O(α'), focusing on the moduli of such compactifications. We begin by studying supersymmetric compactifications to four-dimensional maximally symmetric space, commonly referred to as the Strominger system. The compactifications are of the form M₁₀ = M₄ x X, where M₄ is four-dimensional Minkowski space, and X is a six-dimensional manifold of what we refer to as heterotic SU(3)-structure. We show that this system can be put in terms of a holomorphic operator D on a bundle Q = T* X ⊕ End(TX) ⊕ End(V ) ⊕ TX, defined by a series of extensions. Here V is the E₈ x E₈ gauge-bundle, and TX is the tangent bundle of the compact space X. We proceed to compute the infinitesimal deformation space of this structure, given by TM = H^(0,1)(Q), which constitutes the infinitesimal spectrum of the lower energy four-dimensional theory. In doing so, we find an over counting of moduli by H^(0,1)(End(TX)), which can be reinterpreted as O(α') field redefinitions. In the next part of the thesis, we consider non-maximally symmetric compactifications of the form M₁₀ = M₃ x Y , where M₃ is three-dimensional Minkowski space, and Y is a seven-dimensional non-compact manifold with a G₂-structure. We write X → Y → ℝ, where X is a six dimensional compact space of half- at SU(3)-structure, non-trivially fibered over ℝ. These compactifications are known as domain wall compactifications. By focusing on coset compactifications, we show that the compact space X can be endowed with non-trivial torsion, which can be used in a combination with %α'-effects to stabilise all geometric moduli. The domain wall can further be lifted to a maximally symmetric AdS vacuum by inclusion of non-perturbative effects in a heterotic KKLT scenario. Finally, we consider domain wall compactifications where X is a Calabi-Yau. We show that by considering such compactifications, one can evade the usual no-go theorems for flux in Calabi-Yau compactifications, allowing flux to be used as a tool in such compactifications, even when X is Kähler. The ultimate success of these compactifications depends on the possibility of lifting such vacua to maximally symmetric ones by means of e.g. non-perturbative effects.

by Wong Chun-fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 81-82). / Chapter CHAPTER0 --- Introduction --- p.1 / Chapter CHAPTER1 --- Teichmuller Space of genus g --- p.5 / Chapter 1.1. --- Teichmiiller Space of genus g / Chapter 1.2. --- Fuchsian Model and Discrete subgroup of Aut(H) / Chapter 1.3. --- Fricke Space / Chapter CHAPTER2 --- Hyperbolic Geometry and Fenchel-Nielsen Coordinates --- p.14 / Chapter 2.1. --- Poincare Metric and Hyperbolic Geometry / Chapter 2.2. --- Fenchel-Nielsen Coordinates / Chapter 2.3. --- Fricke-Klein Embedding / Chapter CHAPTER3 --- Quasiconformal Mappings --- p.23 / Chapter 3.1. --- Definitions / Chapter 3.2. --- Existence Theorems on Quasiconformal Mappings / Chapter 3.3. --- Dependence on Beltrami Coefficients / Chapter CHAPTER4 --- Teichmuller Spaces --- p.37 / Chapter 4.1. --- Analytic Construction of Teichmiiller Spaces / Chapter 4.2. --- Teichmiiller mapping and Teichmiiller Theorem / Chapter 4.3. --- Teichmiiller Uniqueness Theorem / Chapter CHAPTER5 --- Complex Analytic Theory of Teichmiiller Spaces --- p.50 / Chapter 5.1. --- Bers' Embedding and the complex structure of Teichmiiller Space / Chapter 5.2. --- Invariance of Complex Structure of Teichmiiller Space / Chapter 5.3. --- Teichmiiller Modular Groups / Chapter 5.4. --- Classification of Teichmiiller Modular Transformations / Chapter CHAPTER6 --- Weil-Petersson Metric --- p.68 / Chapter 6.1. --- Petersson Scalar Product and Reproducing formula / Chapter 6.2. --- Infinitesimal Theory of Teichmuller Spaces / Chapter 6.3. --- Weil-Petersson Metric / BIBLIOGRAPHY --- p.81