Failure analysis of the mobile elevating work platform

This paper presents an investigation of the accident which occurred during startup of the extending structure from the transport position. In order to clarify the causes of crack occurrence along almost the entire surface of the lever cross-section, the authors performed visual, experimental (chemical composition, tensile properties, microhardness) as well as metallographic examinations. Stress states in the critical zone are defined by applying the finite element method (FEM). Based on the investigation results it was concluded that the lever breakdown is predominantly caused by both the 'operating-in' defect (the malfunction of the limit switch) and the 'manufacturing-in' defect (poor weld quality). The investigation results presented in this paper are important because same or similar problems could arise in supporting structures of various types of transportation, construction and mining machines

Low-temperature tension properties of glass-epoxy composite materials

Predmet i cilj ispitivanja prikazanih u ovom radu predstavlja određivanje zatezne čvrstoće (Rm) i modula elastičnosti (EJ staklo-epoksi kompozitnih materijala ispitivanjem na zatezanje na dve različite temperature (t=20°S i t=-50°S). Ispitivanja su izvedena prema standardu na staklo-epoksi kompozitnom materijalu različitih struktura (dve specifične težine ojačanja 210 g/m2H 550 g/m2) i orijentacija ojačanja (0°/90° i ±45°). Doprinos predstavlja i mikromehanička analiza na prelomnim površinama izvedena na stereo i elektronskom mikroskopu kojom se došlo do stvarnih modela nastanka i razvoja oštećenja pri izvedenim ispitivanjima.The aim of this paper was to present the determination of tensile strength Rm and modulus of elasticity Et of glass-epoxy composites at two different temperatures (at room temperature t=20°C, and at t =-50°C). Standard mechanical testing was carried out on glass woven-epoxy composite material with different structures (two specific weights of reinforcement, 210 g/m2 and 550 g/m2) and orientations (0°/90° and ±45°). Micromechanical analysis of failure was performed on a stereo microscope and SEM in order to determine real models and mechanisms of crack

emoji2vec: Learning Emoji Representations from their Description

Many current natural language processing applications for social media rely on representation learning and utilize pre-trained word embeddings. There currently exist several publicly-available, pre-trained sets of word embeddings, but they contain few or no emoji representations even as emoji usage in social media has increased. In this paper we release emoji2vec, pre-trained embeddings for all Unicode emoji which are learned from their description in the Unicode emoji standard. The resulting emoji embeddings can be readily used in downstream social natural language processing applications alongside word2vec. We demonstrate, for the downstream task of sentiment analysis, that emoji embeddings learned from short descriptions outperforms a skip-gram model trained on a large collection of tweets, while avoiding the need for contexts in which emoji need to appear frequently in order to estimate a representation

Probing extreme environments with the Cherenkov Telescope Array

The physics of the non-thermal Universe provides information on the acceleration mechanisms in extreme environments, such as black holes and relativistic jets, neutron stars, supernovae or clusters of galaxies. In the presence of magnetic fields, particles can be accelerated towards relativistic energies. As a consequence, radiation along the entire electromagnetic spectrum can be observed, and extreme environments are also the most likely sources of multi-messenger emission. The most energetic part of the electromagnetic spectrum corresponds to the very-high-energy (VHE, E>100 GeV) gamma-ray regime, which can be extensively studied with ground based Imaging Atmospheric Cherenkov Telescopes (IACTs). The results obtained by the current generation of IACTs, such as H.E.S.S., MAGIC, and VERITAS, demonstrate the crucial importance of the VHE band in understanding the non-thermal emission of extreme environments in our Universe. In some objects, the energy output in gamma rays can even outshine the rest of the broadband spectrum. The Cherenkov Telescope Array (CTA) is the next generation of IACTs, which, with cutting edge technology and a strategic configuration of ~100 telescopes distributed in two observing sites, in the northern and southern hemispheres, will reach better sensitivity, angular and energy resolution, and broader energy coverage than currently operational IACTs. With CTA we can probe the most extreme environments and considerably boost our knowledge of the non-thermal Universe.Comment: Submitted as input to ASTRONET Science Vision and Infrastructure roadmap on behalf of the CTA consortiu

EuCAPT White Paper: Opportunities and Challenges for Theoretical Astroparticle Physics in the Next Decade

Astroparticle physics is undergoing a profound transformation, due to a series of extraordinary new results, such as the discovery of high-energy cosmic neutrinos with IceCube, the direct detection of gravitational waves with LIGO and Virgo, and many others. This white paper is the result of a collaborative effort that involved hundreds of theoretical astroparticle physicists and cosmologists, under the coordination of the European Consortium for Astroparticle Theory (EuCAPT). Addressed to the whole astroparticle physics community, it explores upcoming theoretical opportunities and challenges for our field of research, with particular emphasis on the possible synergies among different subfields, and the prospects for solving the most fundamental open questions with multi-messenger observations.Comment: White paper of the European Consortium for Astroparticle Theory (EuCAPT). 135 authors, 400 endorsers, 133 pages, 1382 reference

Multiwavelength Observations of the Blazar VER J0521+211 during an Elevated TeV Gamma-Ray State

We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly binned light curve is (8.8 ± 0.4) × 10-7 photons m-2 s-1, or ∼37% of the Crab Nebula flux. Multiwavelength observations from X-ray, UV, and optical instruments are also presented. A moderate correlation between the X-ray and TeV gamma-ray fluxes was observed, and the X-ray spectrum appeared harder when the flux was higher. Using the gamma-ray spectrum and four models of the extragalactic background light (EBL), a conservative 95% confidence upper limit on the redshift of the source was found to be z ≤ 0.31. Unlike the gamma-ray and X-ray bands, the optical flux did not increase significantly during the studied period compared to the archival low-state flux. The spectral variability from optical to X-ray bands suggests that the synchrotron peak of the spectral energy distribution (SED) may become broader during flaring states, which can be adequately described with a one-zone synchrotron self-Compton model varying the high-energy end of the underlying particle spectrum. The synchrotron peak frequency of the SED and the radio morphology of the jet from the MOJAVE program are consistent with the source being an intermediate-frequency-peaked BL Lac object