Philipp Blum

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With the field of wireless sensor networks rapidly maturing, the focus shifts from " easy " deployments, like remote monitoring, to more difficult domains where applications impose strict, real-time constraints on performance. One such class of applications is safety critical systems, like fire and burglar alarms, where events detected by sensor nodes have(More)
Clock synchronization is a crucial basic service in typical sensor networks, since the observations of distributed sensors more often than not need to be ordered ("<i>a</i> happened before <i>b</i>") or otherwise related ("<i>a</i> and <i>b</i> happened within a time window of size <i>x</i>") in time. Ad-hoc networks may exhibit characteristics which make(More)
Interval-based synchronization provides the nodes of a distributed system with guaranteed bounds on a common time. This is a crucial piece of infrastructure in many distributed sensing and actuating systems. In this paper, we propose a modification to a known interval-based synchronization algorithm; our new algorithm obtains substantially better results in(More)
We present an evaluation strategy for clock synchronization algorithms. It is based on a combination of measured traces, which provide for realistic performance estimation, and of simulation, which guarantees repeatability. The evaluation strategy includes parameter-optimization to allow for a fair comparison of algorithms; a general-purpose evolutionary(More)
—Geothermal energy use from shallow groundwater systems is attractive for the supply of heat and hot water to buildings. It offers economic and environmental advantages over traditional fossil-fuel based technologies, in particular when large scale systems are well adapted to the always unique hydrogeological conditions. Computer based numerical simulations(More)
— Clock synchronization is a crucial basic service in ad-hoc sensor networks. Most proposed algorithms employ hierarchical communication structures that may be expensive to maintain when nodes are mobile and network topologies are dynamic. Interval-based synchronization has been proposed as particularly suited for sensor networks, as it does not require any(More)
Fractures, such as joints, faults and veins, strongly influence the transport of fluids through rocks by either enhancing or inhibiting flow. Techniques used for the automatic detection of lineaments from satellite images and aerial photographs, LIDAR technologies and borehole televiewers significantly enhanced data acquisition. The analysis of such data is(More)
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