Ingeniero Civil de Minas / Uno de los métodos de explotación que permite la extracción de yacimientos minerales con cuerpos de grandes dimensiones es el método de Block Caving. En dicho método existen diferentes operaciones unitarias, que van desde que se extrae el mineral de la mina hasta que llega a su procesamiento metalúrgico. A partir de la confiabilidad y disponibilidad de los componentes del sistema de manejo de minerales, se puede evaluar la certeza del cumplimiento del plan de producción. Por ello, el objetivo principal de este trabajo es determinar la confiabilidad operacional del proceso de manejo de minerales al interior mina, a partir de un modelo de simulación integrado. Para ello se realizaron simulaciones de distintos escenarios con la variación de parámetros operacionales, obteniéndose la disponibilidad teórica del sistema y el impacto de las labores de mantención en el uso de equipos y recursos. Se tomó como referencia el sistema diseñado para Chuquicamata Subterránea, en particular, el macrobloque N5-1 ubicado en la cota 1841, para el cual se asociaron distintas interferencias operaciones y modos de falla a cada componente. El modelo consta de puntos de extracción, subcalles de producción, parrillas de reducción, piques de traspaso, tolvas de almacenamiento, alimentadores, chancadores y una correa transportadora. Para la simulación se utilizó el software Availability Workbench®, en su módulo AvSim, en el cual se consideraron 1.000 réplicas para un tiempo de 7.200 horas. Se evaluaron un total de 18 escenarios posibles, en los cuales se varió el criterio de ingreso de cuadrilla para la reparación de puntos de extracción, la implementación de mantenciones programadas e inspecciones preventivas y la cantidad de equipos y recursos disponibles para la realización de las labores de reparación y mantención. De los resultados obtenidos, se destaca que el criterio de ingreso de reparación de puntos fue el factor más determinante en la disponibilidad del sistema, mientras que la variación del stock de equipos y recursos y las mantenciones programadas no provocaron un impacto significativo en ésta. El criterio medio de ingreso fue el que entregó la disponibilidad más alta (del orden del 80%) y los componentes más influyentes fueron los puntos de extracción y la correa transportadora. Al comparar la producción planificada con la producción según el modelo de confiabilidad, se tiene resultados similares que fluctúan entre 6,8 a 7 millones de toneladas. Como conclusiones del trabajo realizado se tiene que es de suma importancia elaborar una estrategia que permita la reparación de puntos sin la necesidad de paralizar todo el funcionamiento de las calles, buscar una alternativa de transporte del mineral cuando la correa se encuentre fuera de servicio y, para evitar el deterioro anticipado de los equipos e infraestructuras, es necesario la implementación de una estrategia de mantenciones programadas que además permita optimizar los tiempos productivos y los tiempos detenidos.

This study compared traditional, A/B and accelerated block scheduling and its effects on student achievement and attendance by comparing the differences in student outcomes observed before and after the adoption of block/accelerated block schedules. The independent variable was the use of time in a block-scheduling model. The dependent variables were student outcomes measured by nine indicators based on the Academic Excellence Indicator System in Texas: student attendance, graduation rate, dropout rate, percentage of students taking advanced courses, percentage of students passing all Exit-level Texas Assessment of Academic Skills tests, percentage of students taking College Admissions Tests, mean SAT total score of those students who took the SAT, mean ACT total score of those students who took the ACT, and percentage of students who are at or above criterion on the SAT or ACT of those students taking the SAT or ACT. Data from archival files from the Texas Education Agency's Academic Excellence Indicator System for each respective year of the eight-year longitudinal study was collected. Scheduling models (traditional, alternating block and accelerated block) were investigated. The sample was drawn from the student population of a large urban school district in north central Texas, a district serving approximately 77,000 students. The district has twelve regular high schools serving students in grades nine through twelve. All twelve regular high schools were included in this study. The indicators were analyzed using SPSS multivariate and univariate analysis to compare the means, regression line slopes, and regression line intercepts for each type of schedule: traditional only, traditional prior to A/B block change, traditional prior to accelerated block change, A/B block, and accelerated block. The regression line, slopes, and intercepts were based on separate regression analysis where a school year was used to predict the AEIS indicators for each type of schedule. With the exception of graduation rate, significant difference was found for all dependent variables.

CHDS State/Local / Approved for public release; distribution is unlimited / It has been thirty-three months since the United States was attacked by terrorists on September 11th 2001. Yet, in distributing grants to States and localities to build their capacity for homeland security, the Nation continues to rely on funding formulae that are deeply flawed. Many grants are distributed in ways that ignore need-driven criteria, such as where terrorists are most likely to strike and which targets are most critical. This thesis develops an alternative formula that takes need into account (and therefore is much more likely to send funds where they are required). After reviewing need-driven formulae from a range of fields that might be applied to homeland security, I use the Analytical Hierarchy Process (AHP) to break the objectives of homeland security capacity-building into discreet, measurable components. Then, I analyze the criteria that should be used to build a grant allocation process to accomplish those objectives, including population density, criticality of infrastructure, the threat to a municipality, vulnerability to that threat, and terrorism prevention. The resulting formula is far better structured than the current system to put homeland security grant funds where the Nation most needs them. / Civilian, Assistant Chief Fire Department City of New York

Block copolymers have attracted interests for potential application ranging from dynamic photonic sensors to solid-state ion conductors. However, due to nucleation and growth mechanism, block copolymer inherently forms granular microstructure with defects such as grain boundaries. Understanding the microstructure of block copolymer is thus crucial in many applications because the microstructure determines the transport property of functional fillers such as ions in block copolymer template. Previous research has shown that athermal filler segregated to grain boundary of lamellae block copolymer and retards the grain coarsening. However, the kinetics of this grain boundary segregation during thermal annealing has not been revealed. Polystyrene-b-polyisoprene blended with deuterated polystyrene is used for neutron scattering study on studying the kinetics of grain boundary segregation. Deuterated polystyrene will segregate to grain boundaries, therefore, decorate grain boundary. The filler segregation behavior will be studied by comparing neutron scattering of polystyrene-b-polyisoprene/deuterated polystyrene with different annealing times (at T=130 deg C, duration of 0hr, 3hr, 1day, 3day and 7day, respectively). Invariant (Q) analysis along with grain mapping is conducted to quantitatively analyze the kinetics of grain boundary segregation. This kinetic was in good agreement with the McLean’s kinetic model for grain boundary segregation in metals. By applying Langmuir-Mclean’s segregation isotherm equation, we have predicted the equilibrium concentration of filler in grain boundary by calculating the strain energy stored in grain boundary.

Anterior cruciate ligament reconstruction utilizing a hamstring autograft is a surgical technique that has gained popularity among orthopedic surgeons caring for adolescent patients. While utilization of a hamstring autograft is a revered technique, harvest of the hamstring yields significant pain. Sciatic peripheral nerve blockade has proven to reliably provide analgesia at the hamstring donor site. Single-injection sciatic peripheral nerve blockade is considered a basic and effective technique, making its use following anterior cruciate ligament reconstruction standard practice in many institutions. The duration of action of a single-injection sciatic peripheral nerve blockade may fail to outlast the pain arising from the hamstring donor site, prompting some clinicians to employ continuous sciatic peripheral nerve blockade via an indwelling catheter. A lack of comparative effectiveness studies exists in the literature regarding the duration of action of peripheral nerve blockade necessary to adequately provide pain control following hamstring autograft harvest, resulting in disagreement among clinicians as to best pain control practices. Proponents of continuous sciatic peripheral nerve blockade assert that while more costly, the extended duration of analgesia afforded by this technique improves pain control postoperatively and decreases the use of other pain medications. Advocates of single-injection sciatic peripheral nerve blockade cite concerns associated with continuous sciatic peripheral nerve blockade known to be detrimental to rehabilitation, such as decreased active knee flexion and increased risk of falls. The purpose of this research is to compare the effect of single-injection sciatic PNB to continuous sciatic PNB on 1) postoperative pain control as measured by self-reported pain scores, pain medication use, and unplanned hospital admission due to poor pain control, 2) active knee flexion, and 3) patient satisfaction with pain control following ACL reconstruction with a hamstring autograft. The findings of this study have the potential to guide informed clinical reasoning and decision making regarding sciatic peripheral nerve blockade techniques following hamstring autograft harvest in adolescents undergoing anterior cruciate ligament reconstruction.

The Master's thesis provides readers with a basic analysis of Commission Regulation 330/2010. The mentioned regulation confers a benefit of the so called block exemption on broad spectrum of vertical agreements including in this context also certain agreements among competing undertakings. Since agreements enjoying the benefit of the block exemption are presumed to meet criteria stipulated in Article 101 (3) TFEU, the block exemption eliminates legal uncertainty which undertakings whose agreements distort competition within the meaning of Article 101 (1) TFEU would otherwise face. It follows that it is not necessary to examine such agreements on its merits. Thus, transaction costs are reduced. Structure of the thesis is chosen so that it reflects three main questions concerning applicability of the block exemption, namely whether (i) an agreement falls within the scope of Commission Regulation 330/2010, whether (ii) it contains black clauses (hard-core restrictions) and whether (iii) it contains (non-severable) grey clauses. After a brief description of wider connections and general issues in Chapter One, in Chapter Two the thesis deals with the scope of Commission Regulation 330/2010 with respect to the notion of vertical agreement, the role of intellectual property rights, the treatment of...

The Kabul Block is a lenticular crustal fragment that, along with the Farah, Helmand, and Nuristan terranes, is situated within a tectonic zone known as the Afghan Central Blocks. The Afghan Cent- ral Blocks form within the collision zone between the Indian, Eurasian, and Arabian plates. The Kabul Block consists of a highly-deformed crystalline basement overlain by weakly-deformed Late Paleozoic- Mesozoic sediments. U/Pb SHRIMP analysis of zircon cores from the lowermost basement formations (the Sherdarwaza and/or Khair Khana) indicates the presence of a Neoarchean component (~ 2700 Ma), while the majority of zircon cores yield a range of Early Paleoproterozoic ages (2200 - 2500 Ma). The Sherdarwaza and Khair Khana Formations are comprised of migmatite and orthogneiss with minor marble, quartzite, and amphibolite that reached granulite-facies conditions. Conventional geother- mobarometry and phase equilibria modelling on well preserved granulite-facies assemblages indicates that the rocks reached conditions of approximately 850 řC at up to 7 kbar of pressure. Textural relations indicate that this was a strongly temperature dominated event. U/Pb SHRIMP dating of zircon rims and U-Th-Pb dating of monazite inclusions in granulite-facies garnet suggest that this event occurred in the late...

Neste trabalho foram preparados nanocompósitos de polímeros estirênicos com argilas organofílicas. Os polímeros estudados foram o poliestireno (PS), um copolímero tribloco de poliestireno-b-polibutadieno-b-estireno (SBS) e quatro copolímeros tribloco de poliestirenob- poli(etileno-co-butileno)-b-estireno (SEBS), sendo um deles modificado com anidrido maléico. Os nanocompósitos foram preparados por três técnicas de obtenção: mistura no fundido, solução e uma técnica híbrida que combina as duas primeiras. Os materiais obtidos foram caracterizados por difração de raios X (XRD), microscopia óptica (OM), microscopia eletrônica de transmissão (TEM), espalhamento de raios X a baixo ângulo (SAXS) e também foram realizados estudos reológicos através do ensaio de cisalhamento oscilatório de pequenas amplitudes (SAOS). O grau de dispersão de argila em algumas amostras foi avaliado por uma técnica baseada na análise de imagens obtidas por TEM. Os resultados mostraram que na maioria dos casos foram obtidos nanocompósitos intercalados, graças à presença da fase de PS em cada polímero. Amostras preparadas por solução tiveram o melhor grau de dispersão de argila, e o polímero que resultou na estrutura mais exfoliada foi o SEBS maleatado. Estudos reológicos mostraram-se muito sensíveis à formação de reticulados de partículas de argila nos nanocompósitos, que passaram a ter comportamento semelhante ao de sólidos. A combinação de técnicas de SAXS com reologia foi bastante útil para estudar a morfologia de fases ordenadas em copolímeros em bloco, permitindo identificar e distinguir estruturas lamelares, cilíndricas e esféricas em cada copolímero. Foi possível verificar que a presença de argila perturba a ordem das fases dos copolímeros e causa diferentes efeitos nas propriedades reológicas destes materiais. / In this work nanocomposites of styrenic polymers and organoclays were prepared. The polymers studied were polystyrene (PS), a polystyrene-b-polybutadiene-b-polystyrene triblock copolymer (SBS) and four polystyrene-b-poly(ethylene-co-butylene)-polystyrene triblock copolymers (SEBS), with one containing maleic anhydride. The nanocomposites were prepared using three different techniques: melt mixing, solution casting and a hybrid technique combining the former two. The materials obtained were characterized by x-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM), small angle x-ray scattering (SAXS) and by rheological studies, through small amplitude oscillatory shear tests (SAOS). The degree of clay dispersion was evaluated in some samples using a TEM image analysis technique. The results have shown that in most cases intercalated nanocomposites were obtained, due to the PS phase present in each polymer. Samples prepared by solution had the highest degree of clay dispersion, and the maleated SEBS was the polymer which originated the most exfoliated nanocomposite. The results have also shown that rheological studies are very sensitive to the formation of clay networks within the nanocomposites, which behave more solidlike. The combination of SAXS techniques and rheology was very useful to study the morphology of ordered phases in block copolymers, allowing to identify and distinguish the different structures of each copolymer, such as the lamellar, cylindrical and spherical phases. It was possible to verify that the presence of clay disturbs the phase order in the copolymers and has different effects on the rheological properties of these materials.

Polylactide (PLA) is a biodegradable and biocompatible alternative to traditional petrochemicalbased polymers. Synthesised by the ring-opening polymerisation of lactide (LA), the dehydrated form of lactic acid, PLA sits within a renewable cycle, and can be used in many commodity and biomedical applications. The intrinsic stereochemistry of LA can lead to a variety of polymer microstructures, and current industrially used initiators allow no control over this. Within this thesis a series of investigations into the use of amine tris(phenolate) metal complexes as stereoselective initiators for the ROP of LA are discussed. Chapter 1 introduces the field of ring-opening polymerisation (ROP) via a coordination insertion mechanism, presents previously reported initiators, and examines the influence of stereocomplexation on the physical properties of PLA chains. This introductory chapter also includes an in-depth review of recent developments in poly(phenolate) complexes of Group 4 and rare earth metals. Chapter 2 describes the synthesis of a series of isopropoxide and zwitterionic Group 4 complexes featuring the amine tris(phenolate) ligand motif, with emphasis on the effect of ligand variation on complex structure. The potential of the resulting complexes as initiators for the ROP of LA is also investigated, with in depth kinetic studies allowing for a proposed diastereoselective mechanism of stereocontrol. Chapter 3 details the synthesis of a series of borohydride and amide Group 4 amine tris(phenolate) complexes, and investigates their potential as initiators for the ROP of rac-LA. Chain-end analysis and kinetic studies are included, providing the basis for mechanistic discussions. Chapter 4 focuses on the synthesis of stereoblock PLA materials in a stereospecific manner, and co-block PLA-PEG materials by the reinitiation of short-chain macroinitiators. The effect of stereocomplexation on the thermal properties of these materials is investigated. Chapter 5 concerns the synthesis of a series of isopropanol and zwitterionic rare earth complexes featuring the amine tris(phenolate) ligand motif. The potential of these complexes as initiators for the ROP of rac-LA is also investigated, but only slight stereocontrol was observed in selected cases. Chapter 6 provides details of procedures employed in the synthesis of ligands, complexes and polymers within this thesis, as well as details of the analytical techniques used in their characterisation.

Given a real parameter-dependent matrix, we obtain an algorithm for computing the value of the parameter and corresponding eigenvalue for which two eigenvalues of the matrix coalesce to form a 2-dimensional Jordan block. Our algorithms are based on extended versions of the implicit determinant method of Spence and Poulton [55]. We consider when the eigenvalue is both real and complex, which results in solving systems of nonlinear equations by Newton’s or the Gauss-Newton method. Our algorithms rely on good initial guesses, but if these are available, we obtain quadratic convergence. Next, we describe two quadratically convergent algorithms for computing a nearby defective matrix which are cheaper than already known ones. The first approach extends the implicit determinant method in [55] to find parameter values for which a certain Hermitian matrix is singular subject to a constraint. This results in using Newton’s method to solve a real system of three nonlinear equations. The second approach involves simply writing down all the nonlinear equations and solving a real over-determined system using the Gauss-Newton method. We only consider the case where the nearest defective matrix is real. Finally, we consider the computation of an algebraically simple complex eigenpair of a nonsymmetric matrix where the eigenvector is normalised using the natural 2-norm, which produces only a single real normalising equation. We obtain an under-determined system of nonlinear equations which is solved by the Gauss-Newton method. We show how to obtain an equivalent square linear system of equations for the computation of the desired eigenpairs. This square system is exactly what would have been obtained if we had ignored the non uniqueness and nondifferentiability of the normalisation.