21,027 research outputs found

    Using the INSPIRAL program to search for gravitational waves from low-mass binary inspiral

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    The INSPIRAL program is the LIGO Scientific Collaboration's computational engine for the search for gravitational waves from binary neutron stars and sub-solar mass black holes. We describe how this program, which makes use of the FINDCHIRP algorithm (discussed in a companion paper), is integrated into a sophisticated data analysis pipeline that was used in the search for low-mass binary inspirals in data taken during the second LIGO science run.Comment: 11 pages, 3 figures, submitted to Classical and Quantum Gravity for the special issue of the GWDAW9 Proceeding

    Guidance, flight mechanics and trajectory optimization. Volume 10 - Dynamic programming

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    Dynamic programming and multistage decision processes in guidance, flight mechanics, and trajectory optimizatio

    Guidance, flight mechanics and trajectory optimization. Volume 1 - Coordinate systems and time measure

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    Coordinate measuring system for flight control, and trajectory optimizatio

    Report on the first binary black hole inspiral search in LIGO data

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    The LIGO Scientific Collaboration is currently engaged in the first search for binary black hole inspiral signals in real data. We are using the data from the second LIGO science run and we focus on inspiral signals coming from binary systems with component masses between 3 and 20 solar masses. We describe the analysis methods used and report on preliminary estimates for the sensitivities of the LIGO instruments during the second science run.Comment: 10 pages, 2 figures. Added references for section 2, corrected figure 1. To appear in CQG, in a special issue on the proceedings of the 9th Annual Gravitational Wave Data Analysis Workshop (GWDAW), Annecy, France, Dec. 200

    Sol-Gel Derived Ferroelectric Nanoparticles Investigated by Piezoresponse Force Microscopy

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    Piezoresponse force microscopy (PFM) was used to investigate the ferroelectric properties of sol-gel derived LiNbO3_3 nanoparticles. To determine the degree of ferroelectricity we took large-area images and performed statistical image-analysis. The ferroelectric behavior of single nanoparticles was verified by poling experiments using the PFM tip. Finally we carried out simultaneous measurements of the in-plane and the out-of-plane piezoresponse of the nanoparticles, followed by measurements of the same area after rotation of the sample by 90∘^{\circ} and 180∘^{\circ}. Such measurements basically allow to determine the direction of polarization of every single particle

    Elastic Instability Triggered Pattern Formation

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    Recent experiments have exploited elastic instabilities in membranes to create complex patterns. However, the rational design of such structures poses many challenges, as they are products of nonlinear elastic behavior. We pose a simple model for determining the orientational order of such patterns using only linear elasticity theory which correctly predicts the outcomes of several experiments. Each element of the pattern is modeled by a "dislocation dipole" located at a point on a lattice, which then interacts elastically with all other dipoles in the system. We explicitly consider a membrane with a square lattice of circular holes under uniform compression and examine the changes in morphology as it is allowed to relax in a specified direction.Comment: 15 pages, 7 figures, the full catastroph

    Metallic phase of the quantum Hall effect in four-dimensional space

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    We study the phase diagram of the quantum Hall effect in four-dimensional (4D) space. Unlike in 2D, in 4D there exists a metallic as well as an insulating phase, depending on the disorder strength. The critical exponent ν≈1.2\nu\approx 1.2 of the diverging localization length at the quantum Hall insulator-to-metal transition differs from the semiclassical value ν=1\nu=1 of 4D Anderson transitions in the presence of time-reversal symmetry. Our numerical analysis is based on a mapping of the 4D Hamiltonian onto a 1D dynamical system, providing a route towards the experimental realization of the 4D quantum Hall effect.Comment: 4+epsilon pages, 3 figure

    Calibration Of The Advanced Ligo Detectors For The Discovery Of The Binary Black-Hole Merger Gw150914

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    In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector\u27s differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detector\u27s gravitational-wave response. The gravitational-wave response model is determined by the detector\u27s opto-mechanical response and the properties of its feedback control system. The measurements used to validate the model and characterize its uncertainty are derived primarily from a dedicated photon radiation pressure actuator, with cross-checks provided by optical and radio frequency references. We describe how the gravitational-wave readout signal is calibrated into equivalent gravitational-wave-induced strain and how the statistical uncertainties and systematic errors are assessed. Detector data collected over 38 calendar days, from September 12 to October 20, 2015, contain the event GW150914 and approximately 16 days of coincident data used to estimate the event false alarm probability. The calibration uncertainty is less than 10% in magnitude and 10° in phase across the relevant frequency band, 20 Hz to 1 kHz
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