On the Cost of Participating in a Peer-to-Peer Network

In this paper, we model the cost incurred by each peer participating in a peer-to-peer network. Such a cost model allows to gauge potential disincentives for peers to collaborate, and provides a measure of the ``total cost'' of a network, which is a possible benchmark to distinguish between proposals. We characterize the cost imposed on a node as a function of the experienced load and the node connectivity, and show how our model applies to a few proposed routing geometries for distributed hash tables (DHTs). We further outline a number of open questions this research has raised.Comment: 17 pages, 4 figures. Short version to be published in the Proceedings of the Third International Workshop on Peer-to-Peer Systems (IPTPS'04). San Diego, CA. February 200

On Critical Infrastructure Protection and International Agreements

This paper evaluates the prospects for protecting critical social functions from “cyber” attacks carried out over electronic information networks. In particular, it focuses on the feasibility of devising international laws, conventions or agreements to deter and/or punish perpetrators of such attacks. First,it briefly summarizes existing conventions and laws, and explains to which technological issues they can apply. The paper then turns to a technical discussion of the threats faced by critical infrastructure. By distinguishing between the different types of attacks (theft of information, destructive penetration, denial of service, etc.) that can be conducted, and examining the role of collateral damages in information security, the paper identifies the major challenges in devising and implementing international conventions for critical infrastructure protection. It then turns to a practical examination of how these findings apply to specific instances of critical networks (power grids and water systems, financial infrastructure, air traffic control and hospital networks), and draws conclusions about potential remedies. A notable finding is that critical functions should be isolated from non-critical functions in the network to have a chance to implement viable international agreements; and that, given the difficulty in performing attack attribution, other relevant laws should be designed with the objective of reducing negative externalities that facilitate such attacks

Audit Games with Multiple Defender Resources

Modern organizations (e.g., hospitals, social networks, government agencies) rely heavily on audit to detect and punish insiders who inappropriately access and disclose confidential information. Recent work on audit games models the strategic interaction between an auditor with a single audit resource and auditees as a Stackelberg game, augmenting associated well-studied security games with a configurable punishment parameter. We significantly generalize this audit game model to account for multiple audit resources where each resource is restricted to audit a subset of all potential violations, thus enabling application to practical auditing scenarios. We provide an FPTAS that computes an approximately optimal solution to the resulting non-convex optimization problem. The main technical novelty is in the design and correctness proof of an optimization transformation that enables the construction of this FPTAS. In addition, we experimentally demonstrate that this transformation significantly speeds up computation of solutions for a class of audit games and security games

Successful 2 planes balancing confirm by rotordynamics calculation

Case StudyThis historical case is focus on the vibration behavior of a generator. After a short circuit issue on the grid, the machine train trip. At this time the level of vibration of the generator was acceptable and well below the level of alarm. However, 10 days after the restart of the unit the level of vibration started to increase. The analysis of the data pointed out an increase of the 1X component. There were no signs of rub or other malfunctions. The analysis of the data concluded on an increase of unbalance or a decrease of the dynamic stiffness. Even if, It is unusual to observe such increase of vibration on a generator, the full inspection of the generator was rejected. In order to operate, even if the root cause was not identified, it was decided to balance the generator. The balancing activity was a success using a modal method. Since the root cause was not determined and in order to be sure that the dynamic behavior of the generator was as expected compare to its design, a lateral analysis was done on site using basic information available on site. Comparing the vibration data recording on site with the result of the lateral analysis, it was concluded that the dynamic stiffness of the machine was almost as expected. The increase of vibration could have been due to a real modification of the unbalance or a potential increase of the bearing clearances. The customer could be confident to continue to operate the unit until the next overall

How to detect Electrostatic discharge (ESD) using proximity probes on rotating machines

Case StudyIn this session, a brief introduction about electrostatic discharge phenomena will be done. Then three historical cases with Electrostatic Discharge (ESD) issue will be analyzed in order to explain how to detect Electrostatic Discharge using proximity probes. It will point out that the vibration behavior in case of ESD is not always the same