202 research outputs found
How Much Cooperation Between Government Agencies Is Too Much?: Reconciling United States v. Scrushy, the Corporate Fraud Task Force, and the Nature of Parallel Proceedings
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EMINENT DOMAIN General Provisions and Condemnation Procedure: Provide a Comprehensive Revision of Provisions Regarding the Power of Eminent Domain
No full textThe Act amends the definition of blight, and adds a definition of public use and economic development. The Act amends the process and the powers of eminent domain. The Act increases the procedural requirements of eminent domain, including new notice provisions, additional rights for the condemnee, and new requirements for the condemnor. The Act increases procedural safeguards for property owners by enhancing notice requirements. The Act takes the power of eminent domain out of the hands of development authorities and gives the power to elected officials
GW231123:a binary black hole merger with total mass 190–265 <i>M</i><sub>⊙</sub>
No full textOn 2023 November 23, the two LIGO observatories both detected GW231123, a gravitational-wave signal consistent with the merger of two black holes with masses 137+23-18 M⊙ and 101+22-50 M⊙ (90% credible intervals), at a luminosity distance of 0.7–4.1 Gpc, a redshift of 0.40+0.27-0.25, and with a network signal-to-noise ratio of ∼20.7. Both black holes exhibit high spins— 0.90+0.10-0.19 and 0.80+0.20-0.52, respectively. A massive black hole remnant is supported by an independent ringdown analysis. Some properties of GW231123 are subject to large systematic uncertainties, as indicated by differences in the inferred parameters between signal models. The primary black hole lies within or above the theorized mass gap where black holes between 60–130 M⊙ should be rare, due to pair-instability mechanisms, while the secondary spans the gap. The observation of GW231123 therefore suggests the formation of black holes from channels beyond standard stellar collapse and that intermediate-mass black holes of mass ∼200 M⊙ form through gravitational-wave-driven mergers
Formation control of a group of micro aerial vehicles (MAVs)
No full textCoordinated motion of Unmanned Aerial Vehicles (UAVs) has been a growing research interest in the last decade. In this paper we propose a coordination model that makes use of virtual springs and dampers to generate reference trajectories for a group of quadrotors. Virtual forces exerted on each vehicle are produced by using projected distances between the quadrotors. Several coordinated task scenarios are presented and the performance of the proposed method is verified by simulations
Impact of non-random vibrations in Mössbauer rotor experiments testing time dilation
No full textAll experiments testing time dilation by measuring the spectral shift of a rotating Mössbauer absorber assume that vibrations do not affect the spectral shift because of their purely random nature and claim that the observed shift is due to time dilation only. Our recent experimentusing the Synchrotron M¨ossbauer Source at ESRF revealed, however, a shift due to the non-random periodic vibration patterns caused by the rotor/bearing system. These patterns fit the predictions of the Jeffcott model for such a system with non-zero eccentricity. We havecalculated this shift due to the non-random vibrations and the resulting relative shift between two states when the acceleration of the absorber is anti-parallel and parallel to the source. This relative shift exhibits the same behavior as the observed relative shift. Hence, the effect of the spectral shift due to vibrations cannot be ignored in any M¨ossbauer rotor experiments for testing time dilation. Recommendations for improvement of future rotor experiments testing time dilation are presented
Ground reaction force sensor fault detection and recovery method based on virtual force sensor for walking biped robots
No full textThis paper presents a novel method for ground force sensor faults detection and faulty signal reconstruction using Virtual force Sensor (VFS) for slow walking bipeds. The design structure of the VFS consists of two steps, the total ground reaction force (GRF) and its location estimation for each leg based on the center of mass (CoM) position, the leg kinematics, and the IMU readings is carried on in the first step. In the second step, the optimal estimation of the distributed reaction forces at the contact points in the feet sole of walking biped is carried on. For the optimal estimation, a constraint model is obtained for the distributed reaction forces at the contact points and the quadratic programming optimization method is used to solve for the GRF. The output of the VFS is used for fault detection and recovery. A faulty signal model is formed to detect the faults based on a threshold, and recover the signal using the VFS outputs. The sensor offset, drift, and frozen output faults are studied and tested. The proposed method detects and estimates the faults and recovers the faulty signal smoothly. The validity of the proposed estimation method was confirmed by simulations on 3D dynamics model of the humanoid robot SURALP while walking. The results are promising and prove themselves well in all of the studied fault cases
Observation of gravitational waves from the coalescence of a 2.5\u20134.5 M 99 compact object and a neutron star
No full textAbstract: We report the observation of a coalescing compact binary with component masses 2.5\u20134.5 M 99 and 1.2\u20132.0 M 99 (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO\u2013Virgo\u2013KAGRA detector network on 2023 May 29 by the LIGO Livingston observatory. The primary component of the source has a mass less than 5 M 99 at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find the most probable interpretation of the source to be the coalescence of a neutron star with a black hole that has a mass between the most massive neutron stars and the least massive black holes observed in the Galaxy. We provisionally estimate a merger rate density of 55 12 47 + 127 Gpc 12 3 yr 12 1 for compact binary coalescences with properties similar to the source of GW230529_181500; assuming that the source is a neutron star\u2013black hole merger, GW230529_181500-like sources may make up the majority of neutron star\u2013black hole coalescences. The discovery of this system implies an increase in the expected rate of neutron star\u2013black hole mergers with electromagnetic counterparts and provides further evidence for compact objects existing within the purported lower mass gap.Abstract: We report the observation of a coalescing compact binary with component masses 2.5-4.5 M-circle dot and 1.2-2.0 M-circle dot (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO-Virgo-KAGRA detector network on 2023 May 29 by the LIGO Livingston observatory. The primary component of the source has a mass less than 5 M-circle dot at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find the most probable interpretation of the source to be the coalescence of a neutron star with a black hole that has a mass between the most massive neutron stars and the least massive black holes observed in the Galaxy. We provisionally estimate a merger rate density of 55(-47)(+127) Gpc-3yr(-1) for compact binary coalescences with properties similar to the source of GW230529_181500; assuming that the source is a neutron star-black hole merger, GW230529_181500-like sources may make up the majority of neutron star-black hole coalescences. The discovery of this system implies an increase in the expected rate of neutron star-black hole mergers with electromagnetic counterparts and provides further evidence for compact objects existing within the purported lower mass gap
Search for Gravitational Waves Emitted from SN2023ixf
No full textWe present the results of a search for gravitational-wave transients associated with core-collapse supernova SN 2023ixf, which was observed in the galaxy Messier 101 via optical emission on 2023 May 19, during the LIGO–Virgo–KAGRA 15th Engineering Run. We define a five-day on-source window during which an accompanying gravitational-wave signal may have occurred. No gravitational waves have been identified in data when at least two gravitational-wave observatories were operating, which covered ∼14% of this five-day window. We report the search detection efficiency for various possible gravitational-wave emission models. Considering the distance to M101 (6.7 Mpc), we derive constraints on the gravitational-wave emission mechanism of core-collapse supernovae across a broad frequency spectrum, ranging from 50 Hz to 2 kHz, where we assume the gravitational-wave emission occurred when coincident data are available in the on-source window. Considering an ellipsoid model for a rotating proto-neutron star, our search is sensitive to gravitational-wave energy 1 × 10−4 M⊙c2 and luminosity 2.6 × 10−4 M⊙c2 s−1 for a source emitting at 82 Hz. These constraints are around an order of magnitude more stringent than those obtained so far with gravitational-wave data. The constraint on the ellipticity of the proto-neutron star that is formed is as low as 1.08, at frequencies above 1200 Hz, surpassing past results
Searches for Gravitational Waves from Known Pulsars at Two Harmonics in the Second and Third LIGO-Virgo Observing Runs
No full textWe present a targeted search for continuous gravitational waves (GWs) from 236 pulsars using data from the third observing run of LIGO and Virgo (O3) combined with data from the second observing run (O2). Searches were for emission from the l = m = 2 mass quadrupole mode with a frequency at only twice the pulsar rotation frequency (single harmonic) and the l = 2, m = 1, 2 modes with a frequency of both once and twice the rotation frequency (dual harmonic). No evidence of GWs was found, so we present 95% credible upper limits on the strain amplitudes h0 for the single-harmonic search along with limits on the pulsars' mass quadrupole moments Q22 and ellipticities ε. Of the pulsars studied, 23 have strain amplitudes that are lower than the limits calculated from their electromagnetically measured spin-down rates. These pulsars include the millisecond pulsars J0437-4715 and J0711-6830, which have spin-down ratios of 0.87 and 0.57, respectively. For nine pulsars, their spin-down limits have been surpassed for the first time. For the Crab and Vela pulsars, our limits are factors of ∼100 and ∼20 more constraining than their spin-down limits, respectively. For the dual-harmonic searches, new limits are placed on the strain amplitudes C21 and C22. For 23 pulsars, we also present limits on the emission amplitude assuming dipole radiation as predicted by Brans-Dicke theory
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