12,947 research outputs found
Automatic facial expression tracking for 4D range scans
This paper presents a fully automatic approach of spatio-temporal facial expression tracking for 4D range scans without any manual interventions (such as specifying landmarks). The approach consists of three steps: rigid registration, facial model reconstruction, and facial expression tracking. A Scaling Iterative Closest Points (SICP) algorithm is introduced to compute the optimal rigid registration between a template facial model and a range scan with consideration of the scale problem. A deformable model, physically based on thin shells, is proposed to faithfully reconstruct the facial surface and texture from that range data. And then the reconstructed facial model is used to track facial expressions presented in a sequence of range scans by the deformable model
Observation of enhanced optical spring damping in a macroscopic mechanical resonator and application for parametric instability control in advanced gravitational-wave detectors
We show that optical spring damping in an optomechanical resonator can be enhanced by injecting a phase delay in the laser frequency-locking servo to rotate the real and imaginary components of the optical spring constant. This enhances damping at the expense of optical rigidity. We demonstrate enhanced parametric damping which reduces the Q factor of a 0.1-kg-scale resonator from 1.3×10^5 to 6.5×10^3. By using this technique adequate optical spring damping can be obtained to damp parametric instability predicted for advanced laser interferometer gravitational-wave detectors
Hybrid bounds for twisted L-functions
The aim of this paper is to derive bounds on the critical line Rs 1/2 for L- functions attached to twists f circle times chi of a primitive cusp form f of level N and a primitive character modulo q that break convexity simultaneously in the s and q aspects. If f has trivial nebentypus, it is shown that
L(f circle times chi, s) << (N vertical bar s vertical bar q)(epsilon) N-4/5(vertical bar s vertical bar q)(1/2-1/40),
where the implied constant depends only on epsilon > 0 and the archimedean parameter of f. To this end, two independent methods are employed to show
L(f circle times chi, s) << (N vertical bar s vertical bar q)(epsilon) N-1/2 vertical bar S vertical bar(1/2)q(3/8) and
L(g,s) << D-2/3 vertical bar S vertical bar(5/12)
for any primitive cusp form g of level D and arbitrary nebentypus (not necessarily a twist f circle times chi of level D vertical bar Nq(2))
New multi-parameter Golay 2-complementary sequences and transforms
In this work, we develop a new unified approach to the so-called generalized Golay- Rudin-Shapiro (GRS) 2-complementary multi-parameter sequences. It is based on a new generalized iteration generating construction. © 2018 Institute of Physics Publishing. All rights reserved.This work was supported by the RFBR grant 17-07-00886 and by the Ural State Forest Engineering’s Center of Excellence in”Quantum and Classical Information Technologies for Remote Sensing Systems”
Isoscalar Hamiltonians for light atomic nuclei
The charge-dependent realistic nuclear Hamiltonian for a nucleus, composed of
neutrons and protons, can be successfully approximated by a charge-independent
one. The parameters of such a Hamiltonian, i.e., the nucleon mass and the NN
potential, depend upon the mass number A, charge Z and isospin quantum number T
of state of the studied nucleus.Comment: REVTeX, 22 pages, 3 eps figures, to appear in PR
Feedback control of thermal lensing in a high optical power cavity
This paper reports automatic compensation of strong thermal lensing in a suspended 80 m optical cavity with sapphire test mass mirrors. Variation of the transmitted beam spot size is used to obtain an error signal to control the heating power applied to the cylindrical surface of an intracavity compensation plate. The negative thermal lens created in the compensation plate compensates the positive thermal lens in the sapphire test mass, which was caused by the absorption of the high intracavity optical power. The results show that feedback control is feasible to compensate the strong thermal lensing expected to occur in advanced laser interferometric gravitational wave detectors. Compensation allows the cavity resonance to be maintained at the fundamental mode, but the long thermal time constant for thermal lensing control in fused silica could cause difficulties with the control of parametric instabilities.This research was supported by the Australian
Research Council and the Department of Education,
Science and Training and by the U.S. National Science Foundation,
through LIGO participation in the HOPF
Insulator-to-metal transition in sulfur-doped silicon
We observe an insulator-to-metal (I-M) transition in crystalline silicon
doped with sulfur to non- equilibrium concentrations using ion implantation
followed by pulsed laser melting and rapid resolidification. This I-M
transition is due to a dopant known to produce only deep levels at equilibrium
concentrations. Temperature-dependent conductivity and Hall effect measurements
for temperatures T > 1.7 K both indicate that a transition from insulating to
metallic conduction occurs at a sulfur concentration between 1.8 and 4.3 x
10^20 cm-3. Conduction in insulating samples is consistent with variable range
hopping with a Coulomb gap. The capacity for deep states to effect metallic
conduction by delocalization is the only known route to bulk intermediate band
photovoltaics in silicon.Comment: Submission formatting; 4 journal pages equivalen
Broadband X-ray spectrum of XTE J1550-564 during 2003 outburst
Results of broadband INTEGRAL and RXTE observations of the Galactic
microquasar XTE J1550-564 during outburst in spring 2003 are presented. During
the outburst the source was found in a canonical low/hard spectral state.Comment: 5 pages, 3 figures. Accepted for publication in Astronomy Letter
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