Search results for " projection"

Highly-parallelized simulation of a pixelated LArTPC on a GPU

2023

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The alg…

Projecting Pension Expenditures in Spain: On Uncertainty, Communication and Transparency

2008

In this paper we suggest a set of indicators about the future performance of the Spanish public pension system and a suitable method of representing their uncertainty, in order to improve the communication to the public opinion about its main future challenges. Spain seems a particularly interesting case in Europe to illustrate our proposals, since the social security system has been in surplus for nine consecutive years, in sharp contrast to the projections made just a decade ago, but, at the same time, most projections foresee for Spain one of the highest increases in public expenditure among EU countries due to ageing. We argue that simple, transparent, credible, public and periodic indi…

Study of scintillation light collection, production and propagation in a 4 tonne dual-phase LArTPC

2020

The $3 \times 1 \times 1$ m$^3$ demonstrator is a dual phase liquid argon time projection chamber that has recorded cosmic rays events in 2017 at CERN. The light signal in these detectors is crucial to provide precise timing capabilities. The performances of the photon detection system, composed of five PMTs, are discussed. The collected scintillation and electroluminescence light created by passing particles has been studied in various detector conditions. In particular, the scintillation light production and propagation processes have been analyzed and compared to simulations, improving the understanding of some liquid argon properties.

A GEM-TPC in twin configuration for the Super-FRS tracking of heavy ions at FAIR

2018

The GEM-TPC [1] described herein will be part of the standard beam-diagnostics equipment of the Super-FRS [2] . This chamber will provide tracking information for particle identification at rates up to 1 MHz on an event-by-event basis. The key requirements of operation for these chambers are: close to 100% tracking efficiency under conditions of high counting rate, spatial resolution below 1 mm and a superb large dynamic range covering projectiles from Z=1 up to Z=92. The current prototype consists of two GEM-TPCs inside a single vessel, which are operating independently and have electrical drift fields in opposite directions. The twin configuration is done by flipping one of the GEM-TPCs o…

Improving Scalable K-Means++

2021

Two new initialization methods for K-means clustering are proposed. Both proposals are based on applying a divide-and-conquer approach for the K-means‖ type of an initialization strategy. The second proposal also uses multiple lower-dimensional subspaces produced by the random projection method for the initialization. The proposed methods are scalable and can be run in parallel, which make them suitable for initializing large-scale problems. In the experiments, comparison of the proposed methods to the K-means++ and K-means‖ methods is conducted using an extensive set of reference and synthetic large-scale datasets. Concerning the latter, a novel high-dimensional clustering data generation …

Improvements and applications of the elements of prototype-based clustering

2018

Clustering or cluster analysis is an essential part of data mining, machine learning, and pattern recognition. The most popularly applied clustering methods are partitioning-based or prototype-based methods. Prototype-based clustering methods usually have easy implementability and good scalability. These methods, such as K-means clustering, have been used for different applications in various fields. On the other hand, prototype-based clustering methods are typically sensitive to initialization, and the selection of the number of clusters for knowledge discovery purposes is not straightforward. In the era of big data, in high-velocity, ever-growing datasets, which can also be erroneous, outl…

Can back-projection fully resolve polarity indeterminacy of independent component analysis in study of event-related potential?

2011

a b s t r a c t In the study of event-related potentials (ERPs) using independent component analysis (ICA), it is a traditional way to project the extracted ERP component back to electrodes for correcting its scaling (magnitude and polarity) indeterminacy. However, ICA tends to be locally optimized in practice, and then, the back-projection of a component estimated by the ICA can possibly not fully correct its polarity at every electrode. We demonstrate this phenomenon from the view of the theoretical analysis and numerical simulations and suggest checking and modifying the abnormal polarity of the projected component in the electrode field before further analysis. Moreover, when several co…

Online anomaly detection using dimensionality reduction techniques for HTTP log analysis

2015

Modern web services face an increasing number of new threats. Logs are collected from almost all web servers, and for this reason analyzing them is beneficial when trying to prevent intrusions. Intrusive behavior often differs from the normal web traffic. This paper proposes a framework to find abnormal behavior from these logs. We compare random projection, principal component analysis and diffusion map for anomaly detection. In addition, the framework has online capabilities. The first two methods have intuitive extensions while diffusion map uses the Nyström extension. This fast out-of-sample extension enables real-time analysis of web server traffic. The framework is demonstrated using …

An Efficient Network Log Anomaly Detection System Using Random Projection Dimensionality Reduction

2014

Network traffic is increasing all the time and network services are becoming more complex and vulnerable. To protect these networks, intrusion detection systems are used. Signature-based intrusion detection cannot find previously unknown attacks, which is why anomaly detection is needed. However, many new systems are slow and complicated. We propose a log anomaly detection framework which aims to facilitate quick anomaly detection and also provide visualizations of the network traffic structure. The system preprocesses network logs into a numerical data matrix, reduces the dimensionality of this matrix using random projection and uses Mahalanobis distance to find outliers and calculate an a…

Video projection mapping e arti performative. Una nuova macchina scenotecnica della visione per generare nuovi spazi aumentati

L’oggetto principale della dissertazione è il video projection mapping, un’applicazione di realtà aumentata che utilizza le tecniche di videoproiezione digitale non su tradizionali schermi di proiezione ma sulla realtà stessa, sugli oggetti fisici, ai quali si adatta e si lega in maniera inestricabile, ibridando il livello fisico-reale e il livello digitale. Al contrario di come spesso è stato considerato, il video projection mapping non è solo un gadget tecnologico dei nostri tempi; quando si ibrida con altri media, come le arti performative, diviene linguaggio metaforico, oltrepassando il suo livello tecnologico per produrre significati, per mediare idee. Considerando il suo uso nello spe…