Payload IVA training and simulation

The development of a training program for the intravehicular operation of space shuttle payloads is discussed. The priorities for the program are compliance with established training standards, and accommodating changes. Simulation devices are also reviewed

Sustainable land use against the background of a growing wind power industry

Among the measures discussed as remedies for CO2 emissions reduction renewable energies are prominent as they already provide marketable alternatives to fossil fuels. This holds true especially for wind power, which has multiplied more than twelve-fold on the global scale from 4,800 MW to over 59,000 MW between 1995 and 2005. This is the highest growth rate compared to all other sources of renewable energy. However, is this impressive expansion expected to continue in the near future? Although wind power as a clean technology helps to combat global warming and, as a renewable energy reduces the dependency on the supply of exhaustible fossil fuels, it is not without flaws. There are concerns over adverse effects on human beings, on wildlife and on the landscape. This paper discusses the limits for wind power generation and highlights important conflict areas that may roadblock further expansion of wind power and thus its potential to combat global warming. --

Signal Processing for Compressed Sensing Multiuser Detection

The era of human based communication was longly believed to be the main driver for the development of communication systems. Already nowadays we observe that other types of communication impact the discussions of how future communication system will look like. One emerging technology in this direction is machine to machine (M2M) communication. M2M addresses the communication between autonomous entities without human interaction in mind. A very challenging aspect is the fact that M2M strongly differ from what communication system were designed for. Compared to human based communication, M2M is often characterized by small and sporadic uplink transmissions with limited data-rate constraints. While current communication systems can cope with several 100 transmissions, M2M envisions a massive number of devices that simultaneously communicate to a central base-station. Therefore, future communication systems need to be equipped with novel technologies facilitating the aggregation of massive M2M. The key design challenge lies in the efficient design of medium access technologies that allows for efficient communication with small data packets. Further, novel physical layer aspects have to be considered in order to reliable detect the massive uplink communication. Within this thesis physical layer concepts are introduced for a novel medium access technology tailored to the demands of sporadic M2M. This concept combines advances from the field of sporadic signal processing and communications. The main idea is to exploit the sporadic structure of the M2M traffic to design physical layer algorithms utilizing this side information. This concept considers that the base-station has to jointly detect the activity and the data of the M2M nodes. The whole framework of joint activity and data detection in sporadic M2M is known as Compressed Sensing Multiuser Detection (CS-MUD). This thesis introduces new physical layer concepts for CS-MUD. One important aspect is the question of how the activity detection impacts the data detection. It is shown that activity errors have a fundamentally different impact on the underlying communication system than data errors have. To address this impact, this thesis introduces new algorithms that aim at controlling or even avoiding the activity errors in a system. It is shown that a separate activity and data detection is a possible approach to control activity errors in M2M. This becomes possible by considering the activity detection task in a Bayesian framework based on soft activity information. This concept allows maintaining a constant and predictable activity error rate in a system. Beyond separate activity and data detection, the joint activity and data detection problem is addressed. Here a novel detector based on message passing is introduced. The main driver for this concept is the extrinsic information exchange between different entities being part of a graphical representation of the whole estimation problem. It can be shown that this detector is superior to state-of-the-art concepts for CS-MUD. Besides analyzing the concepts introduced simulatively, this thesis also shows an implementation of CS-MUD on a hardware demonstrator platform using the algorithms developed within this thesis. This implementation validates that the advantages of CS-MUD via over-the-air transmissions and measurements under practical constraints

Diagenetic controls on fluid flow and mechanical properties in Rotliegend reservoir sandstones

Reservoir quality of Rotliegend sandstones is mainly controlled by their permeability, and porosity, and their mechanical properties. Thus, diagenetic porosity-reducing processes need to be understood to evaluate reservoir quality and geotechnical properties in sandstones. Best reservoir qualities are achieved in mature sandstones with large amounts of quartz cementation. The relative length of grain-contacts compared to the respective grain diameter is identified as proxy for rock strength