159 research outputs found
Optimization And Learning For Rough Terrain Legged Locomotion
We present a novel approach to legged locomotion over rough terrain that is thoroughly rooted in optimization. This approach relies on a hierarchy of fast, anytime algorithms to plan a set of footholds, along with the dynamic body motions required to execute them. Components within the planning framework coordinate to exchange plans, cost-to-go estimates, and \u27certificates\u27 that ensure the output of an abstract high-level planner can be realized by lower layers of the hierarchy. The burden of careful engineering of cost functions to achieve desired performance is substantially mitigated by a simple inverse optimal control technique. Robustness is achieved by real-time re-planning of the full trajectory, augmented by reflexes and feedback control. We demonstrate the successful application of our approach in guiding the LittleDog quadruped robot over a variety of types of rough terrain. Other novel aspects of our past research efforts include a variety of pioneering inverse optimal control techniques as well as a system for planning using arbitrary pre-recorded robot behavior
Perancangan Media Promosi Angkringan Estoe Cafe Melalui Komunikasi Visual
Angkringan Estoe merupakan sebuah usaha dibidang kuliner yang berdiri pada tahun 2012 yang berlokasi di Jl. Raya Tampingan -Boja,Kabupaten Kendal,Jawa tengah,kafe yang berkonsep nuansa tradisional ini kalah bersaing dari kompetitornya. Kurangnya promosi dalam perusahaan menyebabkan kurangnya awareness dikalangan masyarakat. Untuk itu, Angkringan Estoe membutuhkan promosi yang berbeda dengan kafe lain agar lebih unggul daripada pesaingnya. Perancangan ini memberikan konsep promosi berdasarkan konsep Angkringan Estoe sebagai kafe yang mengutamakan kenyamanan homie,menu dan suasana tradisional. Dalam perancangan media promosi ini menggunakan metode pengumpulan data kualitatif dengan cara wawancara dengan pemilik dan pengelola Angkringan Estoe. Kegiatan promosi yang dilakukan nantinya menggunakan iklan visual dengan pilihan media yang ditentukan, dengan harapan dapat memperkenalkan kafe bernuansa tradisional yang diminati masyarakat terutama masyarakat Boja
Spectroscopic Confirmation of a Population of Isolated, Intermediate-Mass YSOs
Wide-field searches for young stellar objects (YSOs) can place useful
constraints on the prevalence of clustered versus distributed star formation.
The Spitzer/IRAC Candidate YSO (SPICY) catalog is one of the largest
compilations of such objects (~120,000 candidates in the Galactic midplane).
Many SPICY candidates are spatially clustered, but, perhaps surprisingly,
approximately half the candidates appear spatially distributed. To better
characterize this unexpected population and confirm its nature, we obtained
Palomar/DBSP spectroscopy for 26 of the optically-bright (G<15 mag) "isolated"
YSO candidates. We confirm the YSO classifications of all 26 sources based on
their positions on the Hertzsprung-Russell diagram, H and Ca II line-emission
from over half the sample, and robust detection of infrared excesses. This
implies a contamination rate of <10% for SPICY stars that meet our optical
selection criteria. Spectral types range from B4 to K3, with A-type stars most
common. Spectral energy distributions, diffuse interstellar bands, and Galactic
extinction maps indicate moderate to high extinction. Stellar masses range from
~1 to 7 , and the estimated accretion rates, ranging from
to yr, are typical for YSOs
in this mass range. The 3D spatial distribution of these stars, based on Gaia
astrometry, reveals that the "isolated" YSOs are not evenly distributed in the
Solar neighborhood but are concentrated in kpc-scale dusty Galactic structures
that also contain the majority of the SPICY YSO clusters. Thus, the processes
that produce large Galactic star-forming structures may yield nearly as many
distributed as clustered YSOs.Comment: Accepted for publication in AJ. 22 pages, 9 figures, and 4 tables.
Figure sets are available from
https://sites.astro.caltech.edu/~mkuhn/SPICY/PaperIII
Cosmic Explorer: The U.S. Contribution to Gravitational-Wave Astronomy beyond LIGO
This white paper describes the research and development needed over the next decade to realize "Cosmic Explorer," the U.S. node of a future third-generation detector network that will be capable of observing and characterizing compact gravitational-wave sources to cosmological redshifts
Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers
We study frequency dependent (FD) input-output schemes for signal-recycling
interferometers, the baseline design of Advanced LIGO and the current
configuration of GEO 600. Complementary to a recent proposal by Harms et al. to
use FD input squeezing and ordinary homodyne detection, we explore a scheme
which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are
sub-optimal among all possible input-output schemes, provide a global noise
suppression by the power squeeze factor, while being realizable by using
detuned Fabry-Perot cavities as input/output filters. At high frequencies, the
two schemes are shown to be equivalent, while at low frequencies our scheme
gives better performance than that of Harms et al., and is nearly fully
optimal. We then study the sensitivity improvement achievable by these schemes
in Advanced LIGO era (with 30-m filter cavities and current estimates of
filter-mirror losses and thermal noise), for neutron star binary inspirals, and
for narrowband GW sources such as low-mass X-ray binaries and known radio
pulsars. Optical losses are shown to be a major obstacle for the actual
implementation of these techniques in Advanced LIGO. On time scales of
third-generation interferometers, like EURO/LIGO-III (~2012), with
kilometer-scale filter cavities, a signal-recycling interferometer with the FD
readout scheme explored in this paper can have performances comparable to
existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi
Upper limits on the strength of periodic gravitational waves from PSR J1939+2134
The first science run of the LIGO and GEO gravitational wave detectors
presented the opportunity to test methods of searching for gravitational waves
from known pulsars. Here we present new direct upper limits on the strength of
waves from the pulsar PSR J1939+2134 using two independent analysis methods,
one in the frequency domain using frequentist statistics and one in the time
domain using Bayesian inference. Both methods show that the strain amplitude at
Earth from this pulsar is less than a few times .Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo
Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July
200
Quantum state preparation and macroscopic entanglement in gravitational-wave detectors
Long-baseline laser-interferometer gravitational-wave detectors are operating
at a factor of 10 (in amplitude) above the standard quantum limit (SQL) within
a broad frequency band. Such a low classical noise budget has already allowed
the creation of a controlled 2.7 kg macroscopic oscillator with an effective
eigenfrequency of 150 Hz and an occupation number of 200. This result, along
with the prospect for further improvements, heralds the new possibility of
experimentally probing macroscopic quantum mechanics (MQM) - quantum mechanical
behavior of objects in the realm of everyday experience - using
gravitational-wave detectors. In this paper, we provide the mathematical
foundation for the first step of a MQM experiment: the preparation of a
macroscopic test mass into a nearly minimum-Heisenberg-limited Gaussian quantum
state, which is possible if the interferometer's classical noise beats the SQL
in a broad frequency band. Our formalism, based on Wiener filtering, allows a
straightforward conversion from the classical noise budget of a laser
interferometer, in terms of noise spectra, into the strategy for quantum state
preparation, and the quality of the prepared state. Using this formalism, we
consider how Gaussian entanglement can be built among two macroscopic test
masses, and the performance of the planned Advanced LIGO interferometers in
quantum-state preparation
Searching for a Stochastic Background of Gravitational Waves with LIGO
The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed
the fourth science run, S4, with significantly improved interferometer
sensitivities with respect to previous runs. Using data acquired during this
science run, we place a limit on the amplitude of a stochastic background of
gravitational waves. For a frequency independent spectrum, the new limit is
. This is currently the most sensitive
result in the frequency range 51-150 Hz, with a factor of 13 improvement over
the previous LIGO result. We discuss complementarity of the new result with
other constraints on a stochastic background of gravitational waves, and we
investigate implications of the new result for different models of this
background.Comment: 37 pages, 16 figure
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