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Performance Evaluation - Annual Report Year 3 (2007)

Georg Buss Nils Parasie Daniel Veit Michele Catalano Pablo Chacin Isaac Chao Felix Freitag Leandro Navarro Omer F. Rana Liviu Joita Björn Schnizler Werner Streitberger Torsten Eymann

This report describes the work done and results obtained in third year of the CATNETS project. Experiments carried out with the different configurations of the prototype are reported and simulation results are evaluated with the CATNETS metrics framework. The applicability of the Catallactic approach as market model for service and resource allocation in application layer networks is assessed based on the results and experience gained both from the prototype development and simulations.

CATNETS Final Activity Report (2007)

Werner Streitberger Torsten Eymann

This paper presents the final activity report of the CATNETS project. It summarizes the project objectives, the contractors involved, the work performed and the final results. A description of the dissemination activities concludes the report.

Proof-of-Concept Application - Annual Report Year 3 (2007)

Oscar Ardaiz Pablo Chacin Isaac Chao Felix Freitag Leandro Navarro Liviu Joita Omer F. Rana Werner Streitberger Sebastian Hudert Torsten Eymann

In this report the progress of developing the proof-of-concept application in the CATNETS project is presented. Hence the development of the necessary performance measuring components as well as a distributed application to execute on economic-enhanced Grid/P2P platforms and middleware integration are described.

A Scalability Analysis of Grid allocation Mechanisms (2008)

Michael Reinicke Werner Streitberger Torsten Eymann

This article examines the broker´s behavior with regard to a varying number of participating nodes and shows that incremental losses have to be accepted in central resource allocation when introducing new nodes.

A Policy Framework including Trust and Reputation in Grid Environments (2007)

Torsten Eymann Raimund Matros Stefan König

This paper examines the role of policies in different grid environments. A Grid technology becomes standardized and stable, various business models are envented and increasingly applied, and economic implications can be observed.Asymmetrically distributed information may allow for opportunistic behaviour of service providers or users who exploit the information gap between providers and consumers on the quality of services.

Multi-View Reconstruction of Unknown Objects in the Presence of Known Occlusions (2009)

Stefan Kuhn Dominik Henrich

We present a general method for reconstructing unknown objects (e.g. humans) within a known environment (e.g. tables, racks, robots) which usually has occlusions. These occlusions have to be considered since parts of the unknown objects might be hidden in some or even all camera views. Besides grayscale and color cameras also depth sensors are considered. In order to avoid cluttered reconstructions, plausibility checks are used to eliminate reconstruction artifacts which actually do not contain any unknown object. One application is a supervision/surveillance system for safe human/robot-coexistence and –cooperation. Experiments for a voxel-based implementation are given.

A Survey on Reputation Systems for Artificial Societies (2009)

Tina Balke Stefan König Torsten Eymann

The Internet has caused a revolution in trading. Especially cheap items are now easy to buy and sell on the Internet. As a consequence, sellers nowadays offer a wide range of products on the web, creating an abundance of choice for consumers. Consumers have the opportunity to browse on different auction sites for the item they really want. Along with this success story, however, came the stories of people being cheated by fraudulent online sellers. These frauds cover a range from not delivering what has been promised, the overrating of a product´s condition, to deliberate acts of theft. They are a result of so-called asymmetric information. Trust and reputation mechanisms are intended to address this asymmetric information distribution. This article surveys the most common trust and reputation systems.

Multi-View Reconstruction in-between Known Environments (2010)

Stefan Kuhn Dominik Henrich

We present a novel multi-view 3D reconstruction algorithm which unifies the advantages of several recent reconstruction approaches. Based on a known environment causing occlusions and on the cameras pixel grid discretization, an irregular partitioning of the reconstruction space is chosen. Reconstruction artifacts are rejected by using plausibility checks based on additional information about the objects to be reconstructed. The binary occupancy decision is solely performed in reconstruction space instead of fusing back-projected silhouettes in image space. Hierarchical data structures are used to reconstruct the objects progressively focusing on boundary regions. Thus, the algorithm can be stopped at any time with a certain conservative level of detail. Most parts of the algorithm may be processed in parallel using GPU programming techniques. The main application domain is the surveillance of real environments like in human/robot coexistence and cooperation scenarios.

Parallel Low-Storage Runge-Kutta Solvers for ODE Systems with Limited Access Distance (2010)

Matthias Korch Thomas Rauber

We consider the solution of initial value problems (IVPs) of large systems of ordinary differential equations (ODEs) for which memory space requirements determine the choice of the integration method. In particular, we discuss the space-efficient sequential and parallel implementation of embedded Runge-Kutta (RK) methods. We focus on the exploitation of a special structure of commonly appearing ODE systems, referred to as "limited access distance", to improve scalability and memory usage. Such systems may arise, for example, from the semi-discretization of partial differential equations (PDEs). The storage space required by classical RK methods is directly proportional to the dimension n of the ODE system and the number of stages s of the method. We propose an implementation strategy based on a pipelined processing of the stages of the RK method and show how the memory usage of this computation scheme can be reduced to less than three storage registers by an overlapping of vectors without compromising the choice of method coefficients or the potential for efficient stepsize control. We analyze and compare the scalability of different parallel implementation strategies in detailed runtime experiments on different parallel architectures.

Erhebung Mittelständische Zeitarbeit 2010 (2010)

Christian Lehmann Martin Ratzmann Ricarda B. Bouncken

Der Markt für Personaldienstleistungen zählt zu den am stärksten wachsenden Branchen in Deutschland. Während Entleihunternehmen und Zeitarbeitnehmer Gegenstand vieler Untersuchungen sind, wurden die Personaldienstleister selbst bislang kaum betrachtet. Der vorliegende Bericht ist Ergebnis einer Befragung von 346 Filialen deutscher Zeitarbeitsunternehmen aus dem Frühjahr 2010. Praxisnah werden Strukturmerkmale von Verleihunternehmen und mögliche Erfolgsfaktoren aufgezeigt.

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