Evolution of online algorithms in ATLAS and CMS in Run 2

The Large Hadron Collider has entered a new era in Run 2, with centre-of-mass energy of 13 TeV and instantaneous luminosity reaching $\mathcal{L}_\textrm{inst} = 1.4\times$10$^{34}$ cm$^{-2}$ s$^{-1}$ for pp collisions. In order to cope with those harsher conditions, the ATLAS and CMS collaborations have improved their online selection infrastructure to keep a high efficiency for important physics processes - like W, Z and Higgs bosons in their leptonic and diphoton modes - whilst keeping the size of data stream compatible with the bandwidth and disk resources available. In this note, we describe some of the trigger improvements implemented for Run 2, including algorithms for selection of electrons, photons, muons and hadronic final states.Comment: 6 pages. Presented at The Fifth Annual Conference on Large Hadron Collider Physics (LHCP 2017), Shanghai, China, May 15-20, 201

The CMS Trigger Upgrade for the HL-LHC

The CMS experiment has been designed with a two-level trigger system: the Level-1 Trigger, implemented on custom-designed electronics, and the High Level Trigger, a streamlined version of the CMS offline reconstruction software running on a computer farm. During its second phase the LHC will reach a luminosity of $7.5\times10^{34}\,\textrm{cm}^{-2}\,\textrm{s}^{-1}$ with a pileup of 200 collisions, producing integrated luminosity greater than 3000 fb$^{-1}$ over the full experimental run. To fully exploit the higher luminosity, the CMS experiment will introduce a more advanced Level-1 Trigger and increase the full readout rate from 100 kHz to 750 kHz. CMS is designing an efficient data-processing hardware trigger (Level-1) that will include tracking information and high-granularity calorimeter information. The current conceptual system design is expected to take full advantage of advances in FPGA and link technologies over the coming years, providing a high-performance, low-latency system for large throughput and sophisticated data correlation across diverse sources. The higher luminosity, event complexity and input rate present an unprecedented challenge to the High Level Trigger, that aims to achieve a similar efficiency and rejection factor as today despite the higher pileup and more pure preselection. In this presentation we will discuss the ongoing studies and prospects for the online reconstruction and selection algorithms for the high-luminosity era.Comment: 6 pages, 4 figures. Presented at CHEP 2019 - 24th International Conference on Computing in High Energy and Nuclear Physics, Adelaide, Australia, November 04-08, 2019. Replaced with published versio

The Asymptotics of Wilkinson's Iteration: Loss of Cubic Convergence

One of the most widely used methods for eigenvalue computation is the $QR$ iteration with Wilkinson's shift: here the shift $s$ is the eigenvalue of the bottom $2\times 2$ principal minor closest to the corner entry. It has been a long-standing conjecture that the rate of convergence of the algorithm is cubic. In contrast, we show that there exist matrices for which the rate of convergence is strictly quadratic. More precisely, let $T_X$ be the $3 \times 3$ matrix having only two nonzero entries $(T_X)_{12} = (T_X)_{21} = 1$ and let $T_L$ be the set of real, symmetric tridiagonal matrices with the same spectrum as $T_X$. There exists a neighborhood $U \subset T_L$ of $T_X$ which is invariant under Wilkinson's shift strategy with the following properties. For $T_0 \in U$, the sequence of iterates $(T_k)$ exhibits either strictly quadratic or strictly cubic convergence to zero of the entry $(T_k)_{23}$. In fact, quadratic convergence occurs exactly when $\lim T_k = T_X$. Let $X$ be the union of such quadratically convergent sequences $(T_k)$: the set $X$ has Hausdorff dimension 1 and is a union of disjoint arcs $X^\sigma$ meeting at $T_X$, where $\sigma$ ranges over a Cantor set.Comment: 20 pages, 8 figures. Some passages rewritten for clarit

Representations of people in Urban Building Energy Models

Occupant behaviour is commonly acknowledged as a key driver for variation in building energy performance (Gaetani et al., 2016). ASHRAE (2009) notes it as an important factor in the significant discrepancy between proposed building performance and actual energy consumption. A large body of literature exists dedicated to exploring energy behaviours and the need for more holistic considerations of energy behaviours, but this has not been connected to occupant modelling in Urban Building Energy Models (UBEMs). This paper develops a framework to identify and classify representations of people in UBEMs by reviewing and connecting the behaviour change and UBEM literatures. Combined with the classification of the approaches of people’s representation, we show that schedule-based models perform better although it cannot provide a full explanation of energy practices. While agent-based approaches offer the potential to incorporate the more holistic approaches called for by Kierstead (2006) the computational burdens which result may be excessive at the urban scale. The main framework developed can provide simulation practitioners with insights into energy behaviours

Il Casentino: tradizioni etnofarmacobotaniche nei comuni di Poppi e Bibbiena (Arezzo - Toscana)

The Casentino area: ethnopharmacobotanical traditions in the towns of Poppi and Bibbiena (Arezzo-Tuscany). The results refer an ethnopharmacobotanical study carried out in the territories of Poppi and Bibbiena in the Casentino area. There are 89 plants used in folk medicine; some of them are not known to scientific medicine (Asplenium trichomanes L., Fagus sylvatica L., Malva sylvestris L., Nerium oleander L. and Tamus communis L.)

Critical sets of nonlinear Sturm-Liouville operators of Ambrosetti-Prodi type

The critical set C of the operator F:H^2_D([0,pi]) -> L^2([0,pi]) defined by F(u)=-u''+f(u) is studied. Here X:=H^2_D([0,pi]) stands for the set of functions that satisfy the Dirichlet boundary conditions and whose derivatives are in L^2([0,pi]). For generic nonlinearities f, C=\cup C_k decomposes into manifolds of codimension 1 in X. If f''0, the set C_j is shown to be non-empty if, and only if, -j^2 (the j-th eigenvalue of u -> u'') is in the range of f'. The critical components C_k are (topological) hyperplanes.Comment: 6 pages, no figure

Storm Tracking based on Rain Gauges for Flooding Control in Urban Areas

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