Adaptive cuckoo filters

We introduce the adaptive cuckoo filter (ACF), a data structure for approximate set membership that extends cuckoo filters by reacting to false positives, removing them for future queries. As an example application, in packet processing queries may correspond to flow identifiers, so a search for an element is likely to be followed by repeated searches for that element. Removing false positives can therefore significantly lower the false-positive rate. The ACF, like the cuckoo filter, uses a cuckoo hash table to store fingerprints. We allow fingerprint entries to be changed in response to a false positive in a manner designed to minimize the effect on the performance of the filter. We show that the ACF is able to significantly reduce the false-positive rate by presenting both a theoretical model for the false-positive rate and simulations using both synthetic data sets and real packet trace

Relativistic particle motion of a charge including the radiation reaction

The problem of the electromagnetic radiation of an accelerated charged particle is one of the most controversial issues in Physics since the beginning of the last century representing one of the most popular unsolved problems of the Modern Physics. Different equations of motion for a point charge including the electromagnetic radiation emitted have been proposed throughout history, but all these expressions show some limitations. An equation based on the principle of conservation of energy is proposed for the ultra-relativistic motion. Different examples are analyzed showing that the energy lost by the charge agrees with the relativistic generalization of the Larmor formula. This proposed equation has been compared with the Landau-Lifshitz equation obtaining a good agreement in the range of application of the Landau-Lifshitz formula. Finally, it is discussed a possible variation of the typical relativistic particle integrators (e.g. Boris, Vay or Higuera-Cary methods) in order to include the radiation reaction

Study of the RF pulse heating phenomenon in high gradient accelerating devices by means of analytical approximations

The main objective of this work is to present a simple method, based on analytical expressions, for obtaining a quick approximation of the temperature rise due to the Joule effect inside the metallic walls of an RF accelerating device. This proposal relies on solving the 1D heat-transfer equation for a thick wall, where the heat sources inside the wall are the ohmic losses produced by the RF electromagnetic fields penetrating the metal with finite electrical conductivity. Furthermore, it is discussed how the theoretical expressions of this method can be applied to obtain an approximation to the temperature increase in realistic 3D RF accelerating structures, taking as an example the cavity of an RF electron gun. These theoretical results have been benchmarked with numerical simulations carried out with commercial finite-element method codes, finding good agreement among them

Two-dimensional simulation of the electron transport in a photomultiplier tube

Photomultiplier tubes are widely used in experimental physics because they convert small light signals into a measurable electric current. Although their working principle is well known, it is very difficult to find simulations of the electron transport in these devices. For this reason, the electron transport in the Hamamatsu R13408-100 photomultiplier tube has been simulated in 2D. The software SUPERFISH is used for calculating the electrostatic fields and the Boris method for the effective electron dynamics. The secondary electron emission in the dynodes is implemented using an effective electron model and the modified Vaughan’s model. Some figures of merit for photomultiplier tubes (e.g. the gain, the electron transit time or the transit time spread) in function of the supply voltage and an external magnetic field have been studied obtaining a good qualitative accordance with the Hamamatsu datasheet. In further studies, we are going to compare our simulations with experimental measurements

A quality of service assessment technique for large-scale management of multimedia flows

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-540-75869-3_15Proceedings of 10th IFIP/IEEE International Conference on Management of Multimedia and Mobile Networks and Services, MMNS 2007, San José, USA, October 31 - November 2, 2007This paper presents the concept and preliminary experiments of a system for assessing on the Quality of Service of multimedia flows. The goal is to devise a mechanism that allows a service provider to take action whenever poor quality of service is detected in the delivery of multimedia flows. Such procedure is fully automatic since it is based on a goodness-of-fit test between source and destination packet interarrival histograms. If the null hypothesis of the test is accepted the flow is marked as in good standing, otherwise it is marked as anomalous and the network management system should take action in response. The proposed technique is analyzed in terms of hardware complexity and bandwidth consumption. The results show this technique is feasible and easily deployable at a minimum hardware and bandwidth expense.The authors would like to acknowledge the support of the Comunidad Autónoma de Madrid to this work, under project e-Magerit (S-0505/TIC/000251)

What have we learnt from EUPORIAS climate service prototypes?

The international effort toward climate services, epitomised by the development of the Global Framework for Climate Services and, more recently the launch of Copernicus Climate Change Service has renewed interest in the users and the role they can play in shaping the services they will eventually use. Here we critically analyse the results of the five climate service prototypes that were developed as part of the EU funded project EUPORIAS. Starting from the experience acquired in each of the projects we attempt to distil a few key lessons which, we believe, will be relevant to the wider community of climate service developers