Die vorliegende Dissertation beinhaltet die Modellierung und Optimierung von Direktversturztechnologischen Schemen mit dem Ziel, das optimale technologische Schema für den Einsatz des Schürfkübelbaggers in den Braunkohletagebauen der Mongolei zu ermitteln. Zunächst wurden Untersuchungen zur Charakterisierung der bergbau-geologischen Bedingungen der mongolischen Kohlenlagerstätten unter dem Gesichtspunkt durchgeführt, die Anwendungsmöglichkeiten der Direktversturztechnologie zu verdeutlichen. Danach erfolgten Untersuchungen zur Optimierung und Modellierung der technologischen Schemen der Direktversturztechnologie mit einem Schürfkübelbagger und ihre Einsatzrahmen mit dem Ziel, eine technologisch optimale Variante zu identifizieren. Schließlich wurde das Programm "Dragline" entwickelt, um folgende zwei Aufgaben zu lösen: - Die Auswahl eines Schürfkübelbaggers (bzw. die Auslegerlänge und der Kübelvolumen des Schürfkübelbaggers) nach vorgegebenen Abbauparametern - Die Auswahl der Einsatztechnologie für einen vorhandenen Schürfkübelbagger und die Lagerstättenbedingungen. Die Anwendung des Programms und die Bewertung der vom Programm gelieferten Daten erfolgte anhand eines Beispiels einer mongolischen Lagerstätte.

Die vorliegende Dissertation beinhaltet die Modellierung und Optimierung von Direktversturztechnologischen Schemen mit dem Ziel, das optimale technologische Schema für den Einsatz des Schürfkübelbaggers in den Braunkohletagebauen der Mongolei zu ermitteln. Zunächst wurden Untersuchungen zur Charakterisierung der bergbau-geologischen Bedingungen der mongolischen Kohlenlagerstätten unter dem Gesichtspunkt durchgeführt, die Anwendungsmöglichkeiten der Direktversturztechnologie zu verdeutlichen. Danach erfolgten Untersuchungen zur Optimierung und Modellierung der technologischen Schemen der Direktversturztechnologie mit einem Schürfkübelbagger und ihre Einsatzrahmen mit dem Ziel, eine technologisch optimale Variante zu identifizieren. Schließlich wurde das Programm "Dragline" entwickelt, um folgende zwei Aufgaben zu lösen: - Die Auswahl eines Schürfkübelbaggers (bzw. die Auslegerlänge und der Kübelvolumen des Schürfkübelbaggers) nach vorgegebenen Abbauparametern - Die Auswahl der Einsatztechnologie für einen vorhandenen Schürfkübelbagger und die Lagerstättenbedingungen. Die Anwendung des Programms und die Bewertung der vom Programm gelieferten Daten erfolgte anhand eines Beispiels einer mongolischen Lagerstätte.

This thesis is a review of research done over the course of the past 4 years, divided into two unrelated parts. The rst is set in the context of Bagger-Lambert-Gustavsson models, based on 3-Lie algebras. In particular I will describe theories with metric 3-algebras of inde nite signature: these present elds with negative kinetic terms. The problem can be solved by gaugeing away the non-physical degrees of freedom, to obtain other well understood theories. I will show how this procedure can be easily applied for 3-algebra metrics of any inde nite signature. Part II of this thesis focuses on solutions of topologically massive gravity (TMG): particular attention is devoted to warped AdS3 black holes, which are discussed in great detail. I will present a novel analysis of the near horizon geometries of these solutions. I further propose an approach for searching for new solutions to 3-dimensional gravity based on conformal symmetry. This approach is able to yield most of the known axisymmetric stationary TMG backgrounds.

This paper provides an overview of the challenges and possibilities of the integration of electric drives into diesel-hydraulic excavators. Due to the drivers of emission reduction, the use of renewable energies and more energy efficient systems, a global push leads to the integration of electric drives in excavators. In mobile machinery such as excavators, new possibilities and challenges of the adaptation of the drive train and energy storage arise. Rotational actuators can be powered by direct electric drives to avoid losses of the hydraulic system. Adapted hydraulic system topologies enable recuperation and reduce throttling losses in hydraulic systems. Variable and overall higher electric motor speeds reduce the size of the electric and hydraulic components and enable operation in more efficient operating points. To evaluate possible changes to the traditional hydraulic excavator systems, a simulation model is built and the proposed adaptations are implemented. The paper concludes with the evaluation of the proposed system changes and an outlook for further possibilities of hydraulic system adaptions in relation to the electric drive.

Reducing the energy consumption of off-highway machinery due to poor system efficiency is an urgent challenge. Several advanced and innovative architectures have been proposed over the years to tackle this problem, but very few of them found fertile ground for commercial applications due to increased complexity and cost. In this paper, the design, implementation, and testing of a multi-service Digital Displacement ® Pump architecture applied to an excavator are presented. The Digital Displacement ® Pump allows for a dynamic physical displacement allocation to services at different pressure levels, thus reducing throttling losses required to operate multiple actuators simultaneously. A feed-forward control logic is implemented and applied to the system using a closed-centre architecture. The results indicate a fuel reduction of more than 30% compared to the baseline excavator.

Automation of mobile construction and agricultural equipment has gained wide acceptance based on increases in productivity, safety, and precision; while also helping upskill operators. On construction equipment, after-market automation of earthmoving crawler dozers and graders has driven a conversion of machines to electro-hydraulic (EH) implement control and integration into digital worksites. Unlike the aforementioned machines, conversion of the excavator into a semi or fully autonomous machine presents significant challenges due to kinematics, variable loads, non-linear multi-function of implements, safety, and robustness. The present work demonstrates the retrofit of a pilot-operated 21-ton excavator and development of automated controls to address these challenges. The operator pilot joysticks and existing hydraulic system were retained, while adding capability for autonomous functionality with integrated hardware, controls, and kinematic solvers within a production viable environment. Autonomous features for path planning, multi-function actuator velocity control, EH controls, and safety were developed to prove the value of precise and low latency control hardware for EH excavator operation.

There is a lot of gravitational potential energy waste when hydraulic excavators work, which seriously affects the efficiency of the whole machine and produces a large amount of emissions. In order to reduce the energy consumption and emissions of large hydraulic excavators which the boom is driven by two hydraulic cylinders, an integrated drive and potential energy recuperation principle is proposed. In the implementation, the original two-chamber hydraulic cylinders are replaced by three-chamber hydraulic cylinders with energy storage chambers, and the energy storage chambers are directly connected with the hydraulic accumulator. The dead weight of the working device is balanced by the initial hydraulic pressure of the hydraulic accumulator, and the gravitational potential energy is directly recuperated. A digital prototype is established for the simulation work to verify the energy-saving effect. Then a test prototype is constructed according to the simulation work. The standard 90° loading duty cycle tests show that compared with the standard hydraulic excavators of the same type, in the case of meeting the same digging force, the working efficiency of the excavator increases by 20.7% and the fuel consumption decreases by 17.1%. In terms of 8 hours of work per day, a single excavator can save fuel up to 47 L per day and reduce carbon dioxide emissions by 123.6 kg.