Distinctiveness Centrality in Social Networks

The determination of node centrality is a fundamental topic in social network studies. As an addition to established metrics, which identify central nodes based on their brokerage power, the number and weight of their connections, and the ability to quickly reach all other nodes, we introduce five new measures of Distinctiveness Centrality. These new metrics attribute a higher score to nodes keeping a connection with the network periphery. They penalize links to highly-connected nodes and serve the identification of social actors with more distinctive network ties. We discuss some possible applications and properties of these newly introduced metrics, such as their upper and lower bounds. Distinctiveness centrality provides a viewpoint of centrality alternative to that of established metrics

Performance of the Vickrey auction for digital goods under various bid distributions

The generalized Vickrey auction is analysed as a mechanism for setting prices of digital goods. A selection of models of the bidders' behaviour (embodied by the probability distribution of their bids' values) are employed to derive the optimal auctioneer's choice as to the number of items to sell. The satisfaction levels of both the auctioneer and the bidders are taken into account through the evaluation of the expected revenues, the percentage of winning bidders and their aggregated utilities under each of the probabilistic scenarios considered. (C) 2007 Elsevier B.V. All rights reserved

Pricing of insurance policies against cloud storage price rises

When a company migrates to cloud storage, the way back is neither easy nor cheap. The company is then locked up in the storage contract and exposed to upward market prices, which reduce the company's profit and may even bring it below zero. We propose a protection means based on an insurance contract, by which the cloud purchaser is indemnified when the current storage price exceeds a pre-defined threshold. By applying the financial options theory, we provide a formula for the insurance price (the premium). By using historical data on market prices for disks, we apply the formula in realistic scenarios. We show that the premium grows nearly quadratically with the length of the coverage period as long as this is below one year, but grows more slowly, though faster than linearly, over longer coverage periods

Dynamic, self consistent electro-thermal simulation of power microwave devices including the effect of surface metallizations

We present an efficient simulation technique to account for the thermal spreading effects of surface metallizations in the self-consistent dynamic electro-thermal analysis of power microwave devices. Electro-thermal self-consistency is achieved by solving the coupled nonlinear system made of a temperature dependent device electrical model, and of an approximate description of the device thermal behavior through a thermal impedance matrix. The numerical solution is pursued in the frequency domain by the Harmonic Balance technique. The approach is applied to the thermal stability analysis of power AlGaAs/GaAs HBTs and the results show that metallizations have a significant impact on the occurrence of the device thermal collapse

The value of location in keyword auctions

Sponsored links on search engines are an emerging advertising tool, whereby a number of slots are put on sale through keyword auctions. This is also known as contextual advertising. Slot assignment and pricing in keyword auctions are then essential for the search engine\u2019s management since provide the main stream of revenues, and are typically accomplished by the Generalized Second Price (GSP) mechanism. In GSP the price of slots is a monotone function of the slot location, being larger for the highest slots. Though a higher location is associated with larger revenues, the lower costs associated with the lowest slots may make them more attractive for the advertiser. The contribution of this research is to show, by analytical and simulation results based on the theory of order statistics, that advertisers may not get the optimal slot they aim at (the slot maximizing their expected profit) and that the GSP mechanism may be unfair to all the winning bidders but the one who submitted the lowest bid

Stochastic simulation techniques as related to innovation in communications-navigation-surveillance and air traffic management (CNS/ATM)

The design and operational tuning of the instruments and procedures employed in communications-navigation-surveillance (CNS) and air traffic management (ATM) often relies on stochastic simulation techniques. In this paper the application areas of simulation in the CNS/ATM context are reviewed together with the simulation methods that can help solve the main problems encountered, i.e. quick simulation techniques for the simulation of rare events, and the bootstrap technique for the evaluation of the accuracy of the results

Estimation of traf- fic matrices in the presence of long memory traffic

The estimation of traffic matrices in a communications network on the basis of a set of traffic measurements on the network links is a well-known problem, for which a number of solutions have been proposed when the traffic does not show dependence over time, as in the case of the Poisson process. However, extensive measurements campaigns conducted on IP networks have shown that the traffic exhibits long range dependence. Here a method is proposed for the estimation of traffic matrices in the case of long range dependence, and its theoretical properties are studied. Its merits are then evaluated via a simulation study. Finally, an application to real data is provided

quality management in the design of tlc call centers

immediate Abstract Call centres rely heavily on the self-service paradigm through the use of an automated IVR (Interactive Voice Response) system. The service time delivered by the IVR is a major component of the overall QoS (Quality of Service) delivered by the call centre. We analyse the structure and service times of IVR systems through a case study of five call centres in the telecommunications sector. The service trees of the call centres under survey are reconstructed by complete exploration and analysed through a set of metrics. The present design of service trees leads to service times typically larger than those spent waiting for a human agent and to excessively long announcements, with a negative impact on the overall QoS. Imbalances in the popularity of the services offered by the IVR can be exploited to reduce remarkably the average service time, by properly matching the most popular services with the shortest service times

A rank-and-compare algorithm to detect abnormally low bids in procurement auctions

3noDetecting abnormally low bids in procurement auctions is a recognized problem, since their acceptance could result in the winner not being able to provide the service or work awarded by the auction, which is a significant risk for the auctioneer. A rank-and-compare algorithm is considered to detect such anomalous bids and help auctioneers in achieving an effective rejection decision. Analytical expressions and simulation results are provided for the detection probability, as well as for the false alarm probability. The suggested range of application of the detection algorithm leaves out the cases of many tenderers (more than 20) and quite dispersed bids (coefficient of variation larger than 0.15). An increase in the number of tenderers leads to contrasting effects, since both the false alarm probability and the detection probability are reduced. If the bids are spread over a large range, we have instead a double negative effect, with more false alarms and less detections. The presence of multiple anomalous bids worsens the performance of the algorithm as well. On the other hand, the method is quite robust to the presence of courtesy bids.reservedmixedL. De Giovanni; P. L. Conti; M. NaldiDE GIOVANNI, Livia; P. L., Conti; M., Nald