A Tunable Narrowband Source in the Sub-THz and THz Range at DELTA

At DELTA, a 1.5-GeV electron storage ring operated as a synchrotron light source by the TU Dortmund University, an interaction of ultrashort laser pulses with electron bunches is used to generate broadband as well as tunable narrowband radiation in the frequency range between 75 GHz and 5.6 THz. The performance of the source was studied using two different Fourier-transform spectrometers. It was demonstrated that the source can be used for the characterization and comparison of Schottky-diode based detectors, e.g., an on-chip spectrometer enabling single-shot applications

DELIS: Dynamically Evolving, Large Scale Information Systems

DELIS is an Integrated European Project (IST-001907) founded by the "Complex Systems" Proactive Initiative within the Sixth Framework Programme. Information Systems like the physical Internet, the World Wide Web, telephone networks, mobile ad-hoc networks, or peer-to-peer networks have reached a level that puts them beyond our ability to deploy them, manage them, and keep them functioning correctly through traditional techniques. Reasons for this are their sheer size with millions of users and interconnected devices and their dynamics; they evolve dynamically over time, i.e., components change or are removed or inserted permanently. For such systems, we have to abandon the goal of global optimality. Within DELIS, we therefore concentrate on developing self-regulating and self-repairing mechanisms that, on the one hand, are decentralized, scalable, and adapt to changes in their environments

DELIS: Dynamically Evolving, Large Scale Information Systems

DELIS is an Integrated European Project (IST-001907) founded by the "Complex Systems" Proactive Initiative within the Sixth Framework Programme. Information Systems like the physical Internet, the World Wide Web, telephone networks, mobile ad-hoc networks, or peer-to-peer networks have reached a level that puts them beyond our ability to deploy them, manage them, and keep them functioning correctly through traditional techniques. Reasons for this are their sheer size with millions of users and interconnected devices and their dynamics; they evolve dynamically over time, i.e., components change or are removed or inserted permanently. For such systems, we have to abandon the goal of global optimality. Within DELIS, we therefore concentrate on developing self-regulating and self-repairing mechanisms that, on the one hand, are decentralized, scalable, and adapt to changes in their environments

DELIS: Dynamically Evolving, Large Scale Information Systems

DELIS is an Integrated European Project (IST-001907) founded by the "Complex Systems" Proactive Initiative within the Sixth Framework Programme. Information Systems like the physical Internet, the World Wide Web, telephone networks, mobile ad-hoc networks, or peer-to-peer networks have reached a level that puts them beyond our ability to deploy them, manage them, and keep them functioning correctly through traditional techniques. Reasons for this are their sheer size with millions of users and interconnected devices and their dynamics; they evolve dynamically over time, i.e., components change or are removed or inserted permanently. For such systems, we have to abandon the goal of global optimality. Within DELIS, we therefore concentrate on developing self-regulating and self-repairing mechanisms that, on the one hand, are decentralized, scalable, and adapt to changes in their environments

DELIS: Dynamically Evolving, Large Scale Information Systems

DELIS is an Integrated European Project (IST-001907) founded by the "Complex Systems" Proactive Initiative within the Sixth Framework Programme. Information Systems like the physical Internet, the World Wide Web, telephone networks, mobile ad-hoc networks, or peer-to-peer networks have reached a level that puts them beyond our ability to deploy them, manage them, and keep them functioning correctly through traditional techniques. Reasons for this are their sheer size with millions of users and interconnected devices and their dynamics; they evolve dynamically over time, i.e., components change or are removed or inserted permanently. For such systems, we have to abandon the goal of global optimality. Within DELIS, we therefore concentrate on developing self-regulating and self-repairing mechanisms that, on the one hand, are decentralized, scalable, and adapt to changes in their environments

Data management in hierarchical bus networks

A hierarchical bus network T = (V, E) uses hierarchically, tree-like connected buses as a communication network. New communication technologies like SCI (Scalable Coherent Interface) (see, e.g., [6, 7]) make such networks very attractive, because they allow their easy construction and guarantee reasonable communication performance. Such networks can be modeled as tree networks: leaves correspond to processors, inner nodes to buses, edges to switches, and bandwidths of inner nodes and edges are related to bandwidths of buses and switches, respectively. In this paper we address the problem of static data management. Given a set of shared data objects X and the read and write frequencies from the processors to the shared data objects, the goal is to compute a (maybe redundant) placement of the shared data objects to the processors, such that the congestion (the maximum over the load of all edges and inner nodes, induced by the read and write frequencies, divided by the bandwidth of the edge or inner node, respectively) is minimized. It is known [10] that this problem can be solved optimally in linear time, if inner nodes are allowed to hold copies of shared data objects. In our model, inner nodes correspond to buses and therefore cannot store copies of shared data objects. We show that this restriction increases the complexity of the placement problem drastically: It becomes NP-hard. On the other hand, the main contribution of our paper is an approximation algorithm with runtime O(|X|·|V |·height(T)· log(degree(T))) that increases the congestion by a factor of at most 7