Jörn Altmann

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In this study, we develop a theoretical model based on social network theories and analytical methods for exploring collaboration (co-authorship) networks of scholars. We use measures from social network analysis (SNA) (i.e., normalized degree centrality, normalized closeness centrality, normalized betweenness centrality, normalized eigenvector centrality,(More)
The major shortcoming of Grid middleware systems is the lack of economic-enhanced Grid services. These new services are necessary in order to let Grid users benefit from the properties of the Grid. Those properties comprise the availability of on-demand computational power, simplicity of access to resources, low cost of ownership, and a pay-for-use pricing(More)
This paper discusses the rationales for a Grid market and, in particular, the introduction of a market place for trading commoditized computing resources. The market place proposed makes computing resources from different providers substitutable through virtualization. This includes the definition of a spot and future market as well as the parameters that a(More)
Currently, the Internet service provider market offers two different types of pricing plans. In the USA, the predominant pricing plan is a flat-rate plan. In Europe and Asia, the predominant one is a per-minute pricing plan. Enrolled in such a pricing plan, users have to pay for the connect time to the Internet. Although Internet Service Providers (ISPs)(More)
Although there are many studies for quantifying the academic performance of researchers, such as measuring the scientific performance based on the number of publications, there are no studies about quantifying the collaboration activities of researchers. This study addresses this shortcoming. Based on three measures, namely the collaboration network(More)
pricing of network services, charging for network services, QoS pricing, DiffServ, performance modeling This paper describes a control mechanism for Internet traffic. It is an economic mechanism that enables users to choose different price/QoS priority levels for network services at the user time scale. User time scale means that prices vary at a rate(More)
The Internet Demand Experiment or INDEX is a market and technology trial. Its objective is to determine how much users value different qualities of service for Interent access. Findings from the trial imply that today’s system of flat-rate pricing by ISPs is very inefficient. Flat-rate pricing wastes resources, requires light users to subsidize heavy users,(More)