38 research outputs found
Assessment of energy efficiency and sustainability scenarios in the transport system
Background
Energy Policy is one of the main drivers of Transport Policy. A number of strategies to reduce current energy consumption trends in the transport sector have been designed over the last decades. They include fuel taxes, more efficient technologies and changing travel behavior through demand regulation. But energy market has a high degree of uncertainty and the effectiveness of those policy options should be assessed.
Methods
A scenario based assessment methodology has been developed in the frame of the EU project STEPS. It provides an integrated view of Energy efficiency, environment, social and competitiveness impacts of the different strategies. It has been applied at European level and to five specific Regions.
Concluding remarks
The results are quite site specific dependent. However they show that regulation measures appear to be more effective than new technology investments. Higher energy prices could produce on their turn a deterioration of competitiveness and a threat for social goals
Precise mapping of the magnetic field in the CMS barrel yoke using cosmic rays
This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2010 IOPThe CMS detector is designed around a large 4 T superconducting solenoid, enclosed in a 12 000-tonne steel return yoke. A detailed map of the magnetic field is required for the accurate simulation and reconstruction of physics events in the CMS detector, not only in the inner tracking region inside the solenoid but also in the large and complex structure of the steel yoke, which is instrumented with muon chambers. Using a large sample of cosmic muon events collected by CMS in 2008, the field in the steel of the barrel yoke has been determined with a precision of 3 to 8% depending on the location.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,
and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS
(Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia);
Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR
(Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)
All-sky search for long-duration gravitational wave transients in the first Advanced LIGO observing run
We present the results of a search for long-duration gravitational wave transients in the data of the LIGO Hanford and LIGO Livingston second generation detectors between September 2015 and January 2016 , with a total observational time of 49 d. The search targets gravitational wave transients of 10 – 500 s duration in a frequency band of 24 – 2048 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. No significant events were observed. As a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. We also show that the search is sensitive to sources in the Galaxy emitting at least ∼ 10 − 8 M c 2 in gravitational waves
Directly comparing GW150914 with numerical solutions of Einstein's equations for binary black hole coalescence
We compare GW150914 directly to simulations of coalescing binary black holes in full general relativity, including
several performed specifically to reproduce this event. Our calculations go beyond existing semianalytic
models, because for all simulations – including sources with two independent, precessing spins – we perform
comparisons which account for all the spin-weighted quadrupolar modes, and separately which account for all
the quadrupolar and octopolar modes. Consistent with the posterior distributions reported in LVC-PE[1] (at
the 90% credible level), we find the data are compatible with a wide range of nonprecessing and precessing
simulations. Followup simulations performed using previously-estimated binary parameters most resemble the
data, even when all quadrupolar and octopolar modes are included. Comparisons including only the quadrupolar
modes constrain the total redshifted mass Mz ∈ [64M� − 82M�], mass ratio 1/q = m2/m1 ∈ [0.6, 1], and
effective aligned spin χeff ∈ [−0.3, 0.2], where χeff = (S1/m1 + S2/m2) · Lˆ /M. Including both quadrupolar
and octopolar modes, we find the mass ratio is even more tightly constrained. Even accounting for precession,
simulations with extreme mass ratios and effective spins are highly inconsistent with the data, at any mass.
Several nonprecessing and precessing simulations with similar mass ratio and χeff are consistent with the data.
Though correlated, the components’ spins (both in magnitude and directions) are not significantly constrained
by the data: the data is consistent with simulations with component spin magnitudes a1,2 up to at least 0.8, with
random orientations. Further detailed followup calculations are needed to determine if the data contain a weak
imprint from transverse (precessing) spins. For nonprecessing binaries, interpolating between simulations, we
reconstruct a posterior distribution consistent with previous results. The final black hole’s redshifted mass is
consistent with Mf,z
in the range 64.0M� − 73.5M� and the final black hole’s dimensionless spin parameter is
consistent with af = 0.62 − 0.73. As our approach invokes no intermediate approximations to general relativity
and can strongly reject binaries whose radiation is inconsistent with the data, our analysis provides a valuable
complement to LVC-PE[1]
Effects of waveform model systematics on the interpretation of GW150914
PAPER Effects of waveform model systematics on the interpretation of GW150914 B P Abbott1, R Abbott1, T D Abbott2, M R Abernathy3, F Acernese4,5, K Ackley6, C Adams7, T Adams8, P Addesso9,144, R X Adhikari1, V B Adya10, C Affeldt10, M Agathos11, K Agatsuma11, N Aggarwal12, O D Aguiar13, L Aiello14,15, A Ain16, P Ajith17, B Allen10,18,19, A Allocca20,21, P A Altin22, A Ananyeva1, S B Anderson1, W G Anderson18, S Appert1, K Arai1, M C Araya1, J S Areeda23, N Arnaud24, K G Arun25, S Ascenzi15,26, G Ashton10, M Ast27, S M Aston7, P Astone28, P Aufmuth19, C Aulbert10, A Avila-Alvarez23, S Babak29, P Bacon30, M K M Bader11, P T Baker31, F Baldaccini32,33, G Ballardin34, S W Ballmer35, J C Barayoga1, S E Barclay36, B C Barish1, D Barker37, F Barone4,5, B Barr36, L Barsotti12, M Barsuglia30, D Barta38, J Bartlett37, I Bartos39, R Bassiri40, A Basti20,21, J C Batch37, C Baune10, V Bavigadda34, M Bazzan41,42, C Beer10, M Bejger43, I Belahcene24, M Belgin44, A S Bell36, B K Berger1, G Bergmann10, 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Wei54, M Weinert10, A J Weinstein1, R Weiss12, L Wen52, P Weßels10, T Westphal10, K Wette10, J T Whelan107, B F Whiting6, C Whittle120, D Williams36, R D Williams1, A R Williamson94, J L Willis142, B Willke10,19, M H Wimmer10,19, W Winkler10, C C Wipf1, H Wittel10,19, G Woan36, J Woehler10, J Worden37, J L Wright36, D S Wu10, G Wu7, W Yam12, H Yamamoto1, C C Yancey64, M J Yap22, Hang Yu12, Haocun Yu12, M Yvert8, A Zadrożny118, L Zangrando42, M Zanolin103, J-P Zendri42, M Zevin85, L Zhang1, M Zhang129, T Zhang36, Y Zhang107, C Zhao52, M Zhou85, Z Zhou85, S J Zhu10,29, X J Zhu52, M E Zucker1,12, J Zweizig1 (LIGO Scientific Collaboration, Virgo Collaboration), M Boyle143, T Chu97, D Hemberger51, I Hinder29, L E Kidder143, S Ossokine29, M Scheel51, B Szilagyi51, S Teukolsky143 and A Vano Vinuales94 Hide full author list Published 12 April 2017 • © 2017 IOP Publishing Ltd Classical and Quantum Gravity, Volume 34, Number 10 Focus Issue: Gravitational Waves Article PDF Figures References Citations PDF 258 Total downloads Cited by 1 articles Article has an altmetric score of 3 Turn on MathJax Get permission to re-use this article Share this article Article information Abstract Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect sub-dominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein's equations, any such calibration is accurate only to some non-zero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameter-space coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analysis on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edge-on to the detector over a small range of choices of polarization angles, and also for eccentricities greater than ~0.05. For signals with higher signal-to-noise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitational-wave measurements, making more accurate models desirable for future observations
Search for Post-merger Gravitational Waves from the Remnant of the Binary Neutron Star Merger GW170817
The first observation of a binary neutron star coalescence by the Advanced
LIGO and Advanced Virgo gravitational-wave detectors offers an unprecedented
opportunity to study matter under the most extreme conditions. After such a
merger, a compact remnant is left over whose nature depends primarily on the
masses of the inspiralling objects and on the equation of state of nuclear
matter. This could be either a black hole or a neutron star (NS), with the
latter being either long-lived or too massive for stability implying delayed
collapse to a black hole. Here, we present a search for gravitational waves
from the remnant of the binary neutron star merger GW170817 using data from
Advanced LIGO and Advanced Virgo. We search for short ( s) and
intermediate-duration ( s) signals, which includes
gravitational-wave emission from a hypermassive NS or supramassive NS,
respectively. We find no signal from the post-merger remnant. Our derived
strain upper limits are more than an order of magnitude larger than those
predicted by most models. For short signals, our best upper limit on the
root-sum-square of the gravitational-wave strain emitted from 1--4 kHz is
Hz at 50% detection
efficiency. For intermediate-duration signals, our best upper limit at 50%
detection efficiency is Hz for
a millisecond magnetar model, and
Hz for a bar-mode model. These results indicate that post-merger
emission from a similar event may be detectable when advanced detectors reach
design sensitivity or with next-generation detectors
On the progenitor of binary neutron star merger GW170817
On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ~40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ~2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr.B. P. Abbott … Miftar Ganija … Won Kim … Jesper Munch … David J Ottaway … Peter J Veitch … et al. (LIGO Scientific Collaboration and Virgo Collaboration
Ballast Breakage Analysis Using FBG Acoustic Emission Measurement System
Fibre Bragg grating (FBG) based acoustic emission (AE) measurement technique is utilized to monitor ballast breakage activities during uniaxial compressive loading. AE activity is recorded continuously using an FBG attached to the ballast sample and using a high speed FBG acoustic interrogation system. Crack induced AE events, amplitude, spectrograph of AE frequencies and strain induced by the cracks are obtained using the fibre optic system. This information can be crucial in analyzing ballast breakage, one of the key parameters that determine the permanent settlement of railway track. The successful implementation of the method underpins the potential of using fibre optic acoustic emission method to study ballast breakage with further investigation into the frequency analysis and modelling the spectrum of AE at microscopic level can shed light into a deeper understanding of railway track settlements