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Uncertainty in Operational Modal Analysis of Hydraulic Turbine Components
Gagnon, Martin,Tahan, S.-Antoine,Coutu, Andre Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.4
Operational modal analysis (OMA) allows modal parameters, such as natural frequencies and damping, to be estimated solely from data collected during operation. However, a main shortcoming of these methods resides in the evaluation of the accuracy of the results. This paper will explore the uncertainty and possible variations in the estimates of modal parameters for different operating conditions. Two algorithms based on the Least Square Complex Exponential (LSCE) method will be used to estimate the modal parameters. The uncertainties will be calculated using a Monte-Carlo approach with the hypothesis of constant modal parameters at a given operating condition. In collaboration with Andritz-Hydro Ltd, data collected on two different stay vanes from an Andritz-Hydro Ltd Francis turbine will be used. This paper will present an overview of the procedure and the results obtained.
Proton and Helium Spectra from the CREAM-III Flight
Yoon, Y. S.,Anderson, T.,Barrau, A.,Conklin, N. B.,Coutu, S.,Derome, L.,Han, J. H.,Jeon, J. A.,Kim, K. C.,Kim, M. H.,Lee, H. Y.,Lee, J.,Lee, M. H.,Lee, S. E.,Link, J. T.,Menchaca-Rocha, A.,Mitchell, J American Astronomical Society 2017 The Astrophysical journal Vol.839 No.1
<P>Primary cosmic-ray elemental spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The third CREAM payload (CREAM-III) flew for 29 days during the 2007-2008 Antarctic season. Energies of incident particles above 1 TeV are measured with a calorimeter. Individual elements are clearly separated with a charge resolution of similar to 0.12 e (in charge units) and similar to 0.14 e for protons and helium nuclei, respectively, using two layers of silicon charge detectors. The measured proton and helium energy spectra at the top of the atmosphere are harder than other existing measurements at a few tens of GeV. The relative abundance of protons to helium nuclei is 9.53 +/- 0.03 for the range of 1 TeV/n. to 63 TeV/n. This ratio is considerably smaller than other measurements at a few tens of GeV/n. The spectra become softer above similar to 20 TeV. However, our statistical uncertainties are large at these energies and more data are needed.</P>
Performances of photodiode detectors for top and bottom counting detectors of ISS-CREAM experiment
Hyun, H.J.,Anderson, T.,Angelaszek, D.,Baek, S.J.,Copley, M.,Coutu, S.,Han, J.H.,Huh, H.G.,Hwang, Y.S.,Im, S.,Jeon, H.B.,Kah, D.H.,Kang, K.H.,Kim, H.J.,Kim, K.C.,Kwashnak, K.,Lee, J.,Lee, M.H.,Link, J Elsevier 2015 Nuclear Instruments & Methods in Physics Research. Vol.787 No.-
<P><B>Abstract</B></P> <P>The Cosmic Ray Energetics and Mass (CREAM) experiment at the International Space Station (ISS) aims to elucidate the source and acceleration mechanisms of high-energy cosmic rays by measuring the energy spectra from protons to iron. The instrument is planned for launch in 2015 at the ISS, and it comprises a silicon charge detector, a carbon target, top and bottom counting detectors, a calorimeter, and a boronated scintillator detector. The top and bottom counting detectors are developed for separating the electrons from the protons, and each of them comprises a plastic scintillator and a 20×20 silicon photodiode array. Each photodiode is 2.3cm×2.3cm in size and exhibits good electrical characteristics. The leakage current is measured to be less than 20nA/cm<SUP>2</SUP> at an operating voltage. The signal-to-noise ratio is measured to be better than 70 using commercial electronics, and the radiation hardness is tested using a proton beam. A signal from the photodiode is amplified by VLSI (very-large-scale integration) charge amp/hold circuits, the VA-TA viking chip. Environmental tests are performed using whole assembled photodiode detectors of a flight version. Herein, we present the characteristics of the developed photodiode along with the results of the environmental tests.</P>
Lee, J.,Amare, Y.,Anderson, T.,Angelaszek, D.,Anthony, N.,Cheryian, K.,Choi, G.H.,Copley, M.,Coutu, S.,Derome, L.,Eraud, L.,Hagenau, L.,Han, J.H.,Hong, G.,Huh, H.G.,Hwang, Y.S.,Hyun, H.J.,Im, S.,Jeon, Elsevier 2019 Astroparticle physics Vol.112 No.-
<P><B>Abstract</B></P> <P>The Cosmic Ray Energetics And Mass experiment for the International Space Station (ISS-CREAM) is a space-borne mission designed for the precision measurement of the energy and elemental composition of cosmic rays. The Silicon Charge Detector (SCD), placed at the top of the ISS-CREAM payload, consists of 4 layers. Each layer has 2688 silicon pixels and associated electronics arranged in such a fashion that its active detection area of 78.2 × 73.6 cm<SUP>2</SUP> is free of dead area. The foremost goal of the SCD is to efficiently and precisely measure the charge of cosmic rays passing through it. The 4-layer configuration was chosen to achieve the best precision in measuring the charge of cosmic rays within the constraints on the mass, volume and power allotted to it. The amount of material used for its support structure was minimized as well to reduce the chance of interactions of the cosmic ray within the structure. Given the placement of the SCD, its 4-layer configuration and the minimal amount of material in the cosmic-ray trajectory, the SCD is designed to measure the charge of cosmic rays ranging from protons to iron nuclei with excellent detection efficiency and charge resolution. We present the design and fabrication of the SCD as well as its performance during space environment tests which it underwent successfully. We also present its performance in charge measurement using heavy ions in a beam test at CERN, the European Organization for Nuclear Research.</P>
DISCREPANT HARDENING OBSERVED IN COSMIC-RAY ELEMENTAL SPECTRA
Ahn, H. S.,Allison, P.,Bagliesi, M. G.,Beatty, J. J.,Bigongiari, G.,Childers, J. T.,Conklin, N. B.,Coutu, S.,DuVernois, M. A.,Ganel, O.,Han, J. H.,Jeon, J. A.,Kim, K. C.,Lee, M. H.,Lutz, L.,Maestro, P IOP Publishing 2010 ASTROPHYSICAL JOURNAL LETTERS - Vol.714 No.1
<P>The balloon-borne Cosmic Ray Energetics And Mass experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% of the atmosphere. The instrument is configured with complementary and redundant particle detectors designed to extend direct measurements of cosmic-ray composition to the highest energies practical with balloon flights. All elements from protons to iron nuclei are separated with excellent charge resolution. Here, we report results from the first two flights of similar to 70 days, which indicate hardening of the elemental spectra above similar to 200 GeV/nucleon and a spectral difference between the two most abundant species, protons and helium nuclei. These results challenge the view that cosmic-ray spectra are simple power laws below the so-called knee at similar to 10(15) eV. This discrepant hardening may result from a relatively nearby source, or it could represent spectral concavity caused by interactions of cosmic rays with the accelerating shock. Other possible explanations should also be investigated.</P>
Park, J.M.,Amare, Y.,Anderson, T.,Angelaszek, D.,Anthony, N.,Arnold, H.,Choi, G.H.,Copley, M.,Coutu, S.,Derome, L.,Ebongue, C.,Eraud, L.,Faddis, I.,Han, J.H.,Howley, I.J.,Huh, H.G.,Hwang, Y.S.,Hyun, H Elsevier 2018 ADVANCES IN SPACE RESEARCH Vol.62 No.10
<P><B>Abstract</B></P> <P>The Cosmic Ray Energetics and Mass experiment at the International Space Station (ISS-CREAM) is developed for studying the origin, acceleration and propagation mechanism of high energy cosmic rays. The Top and Bottom Counting Detectors (TCD/BCD), sub-detectors of the ISS-CREAM instrument, are developed for electron/ γ -ray physics. The TCD/BCD help distinguish electrons from protons by comparing the hit and shower width distributions for electrons and protons. The e/p separation capability of the TCD/BCD is studied by using the GEANT3 simulation package, and optimal parameters for the e/p separation are obtained.</P>
The boronated scintillator detector of the ISS-CREAM experiment
Amare, Y.,Anderson, T.,Angelaszek, D.,Anthony, N.,Cheryian, K.,Choi, G.H.,Copley, M.,Coutu, S.,Derome, L.,Eraud, L.,Hagenau, L.,Han, J.H.,Huh, H.G.,Hwang, Y.S.,Hyun, H.J.,Im, S.,Jeon, H.B.,Jeon, J.A. Elsevier 2019 Nuclear Instruments & Methods in Physics Research. Vol.943 No.-
<P><B>Abstract</B></P> <P>The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) instrument is a next-generation experiment for the direct detection and study of cosmic-ray nuclei and electrons. With a long exposure in low Earth orbit, the experiment will determine the particle fluxes and spectral details of cosmic-ray nuclei from hydrogen to iron, over an energy range of about 1 <SUP> 0 12 </SUP> eV to > 1 <SUP> 0 15 </SUP> eV, and of cosmic-ray electrons over an energy range of about 5 × 1 <SUP> 0 10 </SUP> eV to > 1 <SUP> 0 13 </SUP> eV. The instrument was deployed to the ISS in August 2017 on the SpaceX CRS-12 mission. We review the design, implementation and performance of one of the ISS-CREAM detector systems: a boron loaded scintillation detector used in discriminating electron-induced events from the much more abundant cosmic-ray nuclei.</P>
Measurement of delayed fluorescence in plastic scintillator from 1 to 10 μ s
Nutter, S.,Amare, Y.,Anderson, T.,Angelaszek, D.,Anthony, N.,Cheryian, k.,Choi, G.H.,Copley, M.,Coutu, S.,Derome, L.,Eraud, L.,Hagenau, L.,Han, J.H.,Huh, H.G.,Hwang, Y.S.,Hyun, H.J.,Im, S.,Jeon, H.B. Elsevier 2019 Nuclear instruments & methods in physics research. Vol.942 No.-
<P><B>Abstract</B></P> <P>The time dependence of the relative light emission of Eljen Technology EJ-200 polyvinyltoluene-based plastic scintillator was measured between 1 and 10 μ s after the passage of a particle shower, a singly charged particle (atmospheric muon), and with a UV LED exciting the fluor. This was compared in magnitude to the integrated response for the prompt light (within 500 ns of excitation). A model with a time-dependent yield consisting of three exponentially decaying components (fast, medium, and slow) was developed to fit the data. Note that the exact time structure of early (< 1 μ s ) light emission was not measured for individual components, only for all three components together This model assumes all three components share the same rise time. The decay time constants of the fast, medium and slow components are, respectively, 7.8 ns, 490 ns, and 2370 ns. The relative total normalized yields for each component are: fast 95.8%, medium 2.2%, and slow 2.0%.</P>
Performance of a Dual Layer Silicon Charge Detector During CREAM Balloon Flight
Nam, S.,Ahn, H. S.,Allison, P.,Bagliesi, M. G.,Barbier, L.,Beatty, J. J.,Bigongiari, G.,Brandt, T. J.,Jeon, J. A.,Childers, J. T.,Conklin, N. B.,Coutu, S.,DuVernois, M. A.,Ganel, O.,Han, J. H.,Kim, K. IEEE 2007 IEEE transactions on nuclear science Vol.54 No.5
<P>The balloon-borne cosmic-ray experiment CREAM (Cosmic Ray Energetics And Mass) has completed two flights in Antarctica, with a combined duration of 70 days. One of the detectors in the payload is the SCD (silicon charge detector) that measures the charge of high energy cosmic rays. The SCD was assembled with silicon sensors. A sensor is a 4 × 4 array of DC-coupled PIN diode pixels with the total active area of 21 × 16 mm<SUP>2</SUP>. The SCD used during the first flight (December 2004-January 2005) was a single layer device, then upgraded to a dual layer device for the second flight (December 2005-January 2006), covering the total sensitive area of 779 × 795 mm<SUP>2</SUP>. Flight data demonstrated that adding a second layer improved SCD performance, showing excellent particle charge resolution. With a total dissipation of 136 W for the dual layer system, special care was needed in designing thermal paths to keep the detector temperature within its operational range. As a consequence, flight temperatures of the SCD, even at diurnal maximum were kept below 38°C. The SCD mechanical structure was designed to minimize the possibility of damage to the sensors and electronics from the impacts of parachute deployment and landing. The detector was recovered successfully following the flight and is being refurbished for the next flight in 2007. Details of construction, operation, and performance are presented for the dual-layered SCD flown for the second CREAM flight.</P>
COSMIC-RAY PROTON AND HELIUM SPECTRA FROM THE FIRST CREAM FLIGHT
Yoon, Y. S.,Ahn, H. S.,Allison, P. S.,Bagliesi, M. G.,Beatty, J. J.,Bigongiari, G.,Boyle, P. J.,Childers, J. T.,Conklin, N. B.,Coutu, S.,DuVernois, M. A.,Ganel, O.,Han, J. H.,Jeon, J. A.,Kim, K. C.,Le IOP Publishing 2011 The Astrophysical journal Vol.728 No.2
<P>Cosmic-ray proton and helium spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in Antarctica in the 2004-2005 austral summer season. High-energy cosmic-ray data were collected at an average altitude of similar to 38.5 km with an average atmospheric overburden of similar to 3.9 g cm(-2). Individual elements are clearly separated with a charge resolution of similar to 0.15 e (in charge units) and similar to 0.2 e for protons and helium nuclei, respectively. The measured spectra at the top of the atmosphere are represented by power laws with a spectral index of -2.66 +/- 0.02 for protons from 2.5 TeV to 250 TeV and -2.58 +/- 0.02 for helium nuclei from 630 GeV nucleon(-1) to 63 TeV nucleon-1. They are harder than previous measurements at a few tens of GeV nucleon-1. The helium flux is higher than that expected from the extrapolation of the power law fitted to the lower-energy data. The relative abundance of protons to helium nuclei is 9.1 +/- 0.5 for the range from 2.5 TeV nucleon(-1) to 63 TeV nucleon(-1). This ratio is considerably smaller than the previous measurements at a few tens of GeV nucleon(-1).</P>