Open-pit mining is an operation in which blocks from the ground are dug to extract the ore contained in them, and in this process a deeper and deeper pit is formed until the mining operation ends. Mining is often a highly complex industrial operation, with respect to both technological and planning aspects. The latter may involve decisions about which ore to mine and in which order. Furthermore, mining operations are typically capital intensive and long-term, and subject to uncertainties regarding ore grades, future mining costs, and the market prices of the precious metals contained in the ore. Today, most of the high-grade or low-cost ore deposits have already been depleted, and to obtain sufficient profitability in mining operations it is therefore today often a necessity to achieve operational efficiency with respect to both technological and planning issues. In this thesis, we study the open-pit design problem, the open-pit mining scheduling problem, and the open-pit design problem with geological and price uncertainty. These problems give rise to (mixed) discrete optimization models that in real-life settings are large scale and computationally challenging. The open-pit design problem is to find an optimal ultimate contour of the pit, given estimates of ore grades, that are typically obtained from samples in drill holes, estimates of costs for mining and processing ore, and physical constraints on mining precedence and maximal pit slope. As is well known, this problem can be solved as a maximum flow problem in a special network. In a first paper, we show that two well known parametric procedures for finding a sequence of intermediate contours leading to an ultimate one, can be interpreted as Lagrangian dual approaches to certain side-constrained design models. In a second paper, we give an alternative derivation of the maximum flow problem of the design problem. We also study the combined open-pit design and mining scheduling problem, which is the problem of simultaneously finding an ultimate pit contour and the sequence in which the parts of the orebody shall be removed, subject to mining capacity restrictions. The goal is to maximize the discounted net profit during the life-time of the mine. We show in a third paper that the combined problem can also be formulated as a maximum flow problem, if the mining capacity restrictions are relaxed; in this case the network however needs to be time-expanded. In a fourth paper, we provide some suggestions for Lagrangian dual heuristic and time aggregation approaches for the open-pit scheduling problem. Finally, we study the open-pit design problem under uncertainty, which is taken into account by using the concept of conditional value-atrisk. This concept enables us to incorporate a variety of possible uncertainties, especially regarding grades, costs and prices, in the planning process. In real-life situations, the resulting models would however become very computationally challenging.

Using fnite difference methods for partial differential equations, this thesis focuses on the problem of connecting overlapping solution domains in the context of a frst order hyperbolic problem. Especially the stability properties of such constructions is studied, and a stable general implementation of the the test problem is proposed. However, no energy estimate could be found, and indeed proven not to exist in the natural norm. Finally, an example is also put forward where the interface conditions derived are, for stability considerations, incompatible with the boundary conditions in a coupled system of hyperbolic equations.

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In this paper the reflection-extension of one-dimensional quasiminimizers is studied.A brief introduction to quasiminimizers, focused on the one-dimensional ones, is given.The main result of the study concerns the size of the quasiminimizing constant of theextended function relative to the unextended one. Previous work by O. Martio gives anupper bound for this relation. This bound is lowered, and the new bound is proven to besharp.Sharp quasiminimizer constants are calculated for a few simple functions and theirreflection-extensions. / I det här arbetet studeras reflektionsutvidgningen av endimensionella kvasiminimerare.En kortfattad introduktion till kvasiminimerare, fokuserad på de endimensionella, ges.Huvudresultatet av arbetet rör storleken av kvasiminimerarkonstanten för den utvidgade funktionen i förhållande till den outvidgade. Tidigare arbete av O. Martio ger en övre gräns för detta förhållande. Den  gränsen sänks, och den nya gränsen visas vara skarp.Skarpa kvasiminimerarkonstanter ges för ett par enkla funktioner och för deras reflektionsutvidgningar.

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Syftet med den här undersökningen är att få veta vad eleverna tycker om att räkna med problemlösningsuppgifter, se om det kan finnas några nackdelar med att enbart använda sig av olika arbetsmaterial som innehåller problemlösningsuppgifter, samt att se hur dagens läroböcker behandlar området med problemlösning.

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