Search results for "Real-time computing"
showing 10 items of 366 documents
The ATLAS level-1 trigger: Status of the system and experience from commissioning with cosmic ray muons
2007
The detector at CERN's large hadron collider (LHC) was exposed to proton-proton collisions from beams crossing at 40 MHz. A three-level trigger system will select potentially interesting events in order to reduce this rate to 100- 200 Hz. A trigger decision is made by the Level-1 central trigger processor (CTP) reducing the incoming rate to less than 100 kHz. The Level-1 decision is based on calorimeter information and hits in dedicated muon trigger detectors. The final Level-1 trigger system is currently being installed in the experiment with completion expected in autumn 2007. Cosmic ray data are regularly recorded as an increasing fraction of the trigger system comes online. We present a…
Pre-production validation of the ATLAS level-1 calorimeter trigger system
2006
The Level-1 Calorimeter Trigger is a major part of the first stage of event selection for the ATLAS experiment at the LHC. It is a digital, pipelined system with several stages of processing, largely based on FPGAs, which perform programmable algorithms in parallel with a fixed latency to process about 300 Gbyte/s of input data. The real-time output consists of counts of different types of trigger objects and energy sums. Prototypes of all module types have been undergoing intensive testing before final production during 2005. Verification of their correct operation has been performed stand-alone and in the ATLAS test-beam at CERN. Results from these investigations will be presented, along …
Classification methods for noise transients in advanced gravitational-wave detectors II: performance tests on Advanced LIGO data
2017
The data taken by the advanced LIGO and Virgo gravitational-wave detectors contains short duration noise transients that limit the significance of astrophysical detections and reduce the duty cycle of the instruments. As the advanced detectors are reaching sensitivity levels that allow for multiple detections of astrophysical gravitational-wave sources it is crucial to achieve a fast and accurate characterization of non-astrophysical transient noise shortly after it occurs in the detectors. Previously we presented three methods for the classification of transient noise sources. They are Principal Component Analysis for Transients (PCAT), Principal Component LALInference Burst (PC-LIB) and W…
On the hardness of evaluating criticality of activities in a planar network with duration intervals
2003
Complexity results for problems of evaluating the criticality of activities in planar networks with duration time intervals are presented. We show that the problems of asserting whether an activity is possibly critical, and of computing bounds on the float of an activity in these networks are NP-complete and NP-hard, respectively.
Combining hectometric and decametric satellite observations to provide near real time decametric FAPAR product
2017
Abstract A wide range of ecological, agricultural, hydrological and meteorological applications at local to regional scales requires decametric biophysical data. However, before the launch of SENTINEL-2A, only few decametric products are produced and most of them remain limited by the small number of available observations, mostly due to a moderate revisit frequency combined with cloud occurrence. Conversely, kilometric and hectometric biophysical products are now widely available with almost complete and continuous coverage, but the associated spatial resolution limits the application over heterogeneous landscapes. The objective of this study is to combine unfrequent decametric spatial res…
Brief communication: Vehicle routing problem and UAV application in the post-earthquake scenario
2017
Abstract. In this paper we simulate a Unmanned Aerial Vehicle's (UAV) recognition after a possible case of diffuse damage after a seismic event in the town of Acireale (Sicily, Italy). Given a set of sites (84 relevant buildings) and the range of the UAV, we are able to find the number of vehicles to employ and the shortest survey path. The problem of finding the shortest survey path is an operational research problem called Vehicle Routing Problem (VRP) whose solution is known to be computationally time-consuming. We used the Simulated Annealing (SA) heuristic that is able to provide stable solutions in relatively short computing time. We also examined the distribution of the cost of the s…
Smart grid-aware scheduling in data centres
2015
In several countries the expansion and establishment of renewable energies result in widely scattered and often weather-dependent energy production, decoupled from energy demand. Large, fossil-fuelled power plants are gradually replaced by many small power stations that transform wind, solar and water power into electrical power. This leads to changes in the historically evolved power grid that favours top-down energy distribution from a backbone of large power plants to widespread consumers. Now, with the increase of energy production in lower layers of the grid, there is also a bottom-up flow of the grid infrastructure compromising its stability. In order to locally adapt the energy deman…
Performance Analysis of Synchronous Duty-Cycled MAC Protocols
2015
In this letter, we propose an analytical model to evaluate the performance of the S-MAC protocol. The proposed model improves the accuracy of previous models in two aspects. First, it incorporates the dependence among the nodes within a cluster by defining a DTMC that models the number of active nodes, whereas the previous models considered that nodes were mutually independent. Second, it proposes new methods for calculating packet delay and energy consumption. The analytical model is validated through discrete-event based simulations. Numerical results demonstrate that the proposed analytical model and methods yield accurate results under realistic assumptions
Link adaptation with combined optimal frame size and rate selection in error-prone 802.11n networks
2008
In error-prone channel with low SNRs, the network throughput may drop significantly if the packet length becomes too large. On the other hand, too much protocol overhead will be introduced if the packet length is too small. In this paper, we study this tradeoff and propose an adaptive frame size algorithm for A-MPDU in 802.11n networks, which can maximize the throughput by selecting the optimized frame length under different channel conditions. When used together with rate selection, the network throughput can be further improved. Both analytical model and simulation results are presented, demonstrating that our algorithm outperforms the fixed length transmission scheme in 802.11n networks …
Energy-Efficiency and Coverage Quality Management for Reliable Diagnostics in Wireless Sensor Networks
2020
International audience; The processing of data and signals provided by sensors aims at extracting rnrelevant features which can be used to assess and diagnose the health state rnof the monitored targets. Nevertheless, Wireless Sensor Networks (WSNs) present rna number of shortcomings that have an impact on the quality of the gathered rndata at the sink level, leading to imprecise diagnostics rnof the observed targets. To improve data accuracy, two main critical and related issues, namely the energy consumption and coverage quality, need to be considered. The goal is to maximize the network lifetime while guaranteeing the complete coverage of all the targets. Unfortunately, these performance…