471 research outputs found
Implementation of a modified Nesterov's Accelerated quasi-Newton Method on Tensorflow
Recent studies incorporate Nesterov's accelerated gradient method for the
acceleration of gradient based training. The Nesterov's Accelerated
Quasi-Newton (NAQ) method has shown to drastically improve the convergence
speed compared to the conventional quasi-Newton method. This paper implements
NAQ for non-convex optimization on Tensorflow. Two modifications have been
proposed to the original NAQ algorithm to ensure global convergence and
eliminate linesearch. The performance of the proposed algorithm - mNAQ is
evaluated on standard non-convex function approximation benchmark problems and
microwave circuit modelling problems. The results show that the improved
algorithm converges better and faster compared to first order optimizers such
as AdaGrad, RMSProp, Adam, and the second order methods such as the
quasi-Newton method.Comment: Paper published in 2018 17th IEEE International Conference on Machine
Learning and Applications (ICMLA
Classical Planning in Deep Latent Space
Current domain-independent, classical planners require symbolic models of the
problem domain and instance as input, resulting in a knowledge acquisition
bottleneck. Meanwhile, although deep learning has achieved significant success
in many fields, the knowledge is encoded in a subsymbolic representation which
is incompatible with symbolic systems such as planners. We propose Latplan, an
unsupervised architecture combining deep learning and classical planning. Given
only an unlabeled set of image pairs showing a subset of transitions allowed in
the environment (training inputs), Latplan learns a complete propositional PDDL
action model of the environment. Later, when a pair of images representing the
initial and the goal states (planning inputs) is given, Latplan finds a plan to
the goal state in a symbolic latent space and returns a visualized plan
execution. We evaluate Latplan using image-based versions of 6 planning
domains: 8-puzzle, 15-Puzzle, Blocksworld, Sokoban and Two variations of
LightsOut.Comment: Under review at Journal of Artificial Intelligence Research (JAIR
Temporal and Spatial Analyses of Spectral Indices of Nonthermal Emissions Derived from Hard X-Rays and Microwaves
We studied electron spectral indices of nonthermal emissions seen in hard
X-rays (HXRs) and in microwaves. We analyzed 12 flares observed by the Hard
X-ray Telescope aboard {\it Yohkoh}, Nobeyama Radio Polarimeters (NoRP), and
the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived
from total fluxes of hard X-rays and microwaves. Except for four events, which
have very soft HXR spectra suffering from the thermal component, these flares
show a gap between the electron spectral indices derived from
hard X-rays and those from microwaves
() of about 1.6. Furthermore, from
the start to the peak times of the HXR bursts, the time profiles of the HXR
spectral index evolve synchronously with those of the microwave
spectral index , keeping the constant gap. We also examined the
spatially resolved distribution of the microwave spectral index by using NoRH
data. The microwave spectral index tends to be larger, which
means a softer spectrum, at HXR footpoint sources with stronger magnetic field
than that at the loop tops. These results suggest that the electron spectra are
bent at around several hundreds of keV, and become harder at the higher energy
range that contributes the microwave gyrosynchrotron emission.Comment: 24 pages, 6 figures, accepted for publication in Ap
Imaging Spectroscopy on Preflare Coronal Nonthermal Sources Associated with the 2002 July 23 Flare
We present a detailed examination on the coronal nonthermal emissions during
the preflare phase of the X4.8 flare that occurred on 2002 July 23. The
microwave (17 GHz and 34 GHz) data obtained with Nobeyama Radioheliograph, at
Nobeyama Solar Radio Observatory and the hard X-ray (HXR) data taken with {\it
Reuven Ramaty High Energy Solar Spectroscopic Imager} obviously showed
nonthermal sources that are located above the flare loops during the preflare
phase. We performed imaging spectroscopic analyses on the nonthermal emission
sources both in microwaves and in HXRs, and confirmed that electrons are
accelerated from several tens of keV to more than 1 MeV even in this phase. If
we assume the thin-target model for the HXR emission source, the derived
electron spectral indices () is the same value as that from
microwaves () within the observational uncertainties, which implies
that the distribution of the accelerated electrons follows a single power-law.
The number density of the microwave-emitting electrons is, however, larger than
that of the HXR-emitting electrons, unless we assume low ambient plasma density
of about cm for the HXR-emitting region. If we adopt
the thick-target model for the HXR emission source, on the other hand, the
electron spectral index () is much different, while the gap of the
number density of the accelerated electrons is somewhat reduced.Comment: 21 pages, 6 figures, ApJ accepte
Effects of Trigger Point Acupuncture Treatment on Temporomandibular Disorders: A Preliminary Randomized Clinical Trial
AbstractWe compared the effects of trigger point acupuncture with that of sham acupuncture treatments on pain and oral function in patients with temporomandibular disorders (TMDs). This 10-week study included 16 volunteers from an acupuncture school with complaints of chronic temporomandibular joint myofascial pain for at least 6 months. The participants were randomized to one of two groups, each receiving five acupuncture treatment sessions. The trigger point acupuncture group received treatment at trigger points for the same muscle, while the other acupuncture group received sham treatment on the trigger points. Outcome measures were pain intensity (visual analogue scale) and oral function (maximal mouth opening). After treatment, pain intensity was less in the trigger point acupuncture group than in the sham treatment group, but oral function remained unchanged in both groups. Pain intensity decreased significantly between pretreatment and 5 weeks after trigger point (p<0.001) and sham acupunctures (p<0.050). Group comparison using the area under the curve demonstrated a significant difference between groups (p=0.0152). Compared with sham acupuncture therapy, trigger point acupuncture therapy may be more effective for chronic temporomandibular joint myofascial pain
A Stochastic Variance Reduced Nesterov's Accelerated Quasi-Newton Method
Recently algorithms incorporating second order curvature information have
become popular in training neural networks. The Nesterov's Accelerated
Quasi-Newton (NAQ) method has shown to effectively accelerate the BFGS
quasi-Newton method by incorporating the momentum term and Nesterov's
accelerated gradient vector. A stochastic version of NAQ method was proposed
for training of large-scale problems. However, this method incurs high
stochastic variance noise. This paper proposes a stochastic variance reduced
Nesterov's Accelerated Quasi-Newton method in full (SVR-NAQ) and limited
(SVRLNAQ) memory forms. The performance of the proposed method is evaluated in
Tensorflow on four benchmark problems - two regression and two classification
problems respectively. The results show improved performance compared to
conventional methods.Comment: Accepted in ICMLA 201
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