4,505 research outputs found
Applying Deep Bidirectional LSTM and Mixture Density Network for Basketball Trajectory Prediction
Data analytics helps basketball teams to create tactics. However, manual data
collection and analytics are costly and ineffective. Therefore, we applied a
deep bidirectional long short-term memory (BLSTM) and mixture density network
(MDN) approach. This model is not only capable of predicting a basketball
trajectory based on real data, but it also can generate new trajectory samples.
It is an excellent application to help coaches and players decide when and
where to shoot. Its structure is particularly suitable for dealing with time
series problems. BLSTM receives forward and backward information at the same
time, while stacking multiple BLSTMs further increases the learning ability of
the model. Combined with BLSTMs, MDN is used to generate a multi-modal
distribution of outputs. Thus, the proposed model can, in principle, represent
arbitrary conditional probability distributions of output variables. We tested
our model with two experiments on three-pointer datasets from NBA SportVu data.
In the hit-or-miss classification experiment, the proposed model outperformed
other models in terms of the convergence speed and accuracy. In the trajectory
generation experiment, eight model-generated trajectories at a given time
closely matched real trajectories
FRMDN: Flow-based Recurrent Mixture Density Network
Recurrent Mixture Density Networks (RMDNs) are consisted of two main parts: a
Recurrent Neural Network (RNN) and a Gaussian Mixture Model (GMM), in which a
kind of RNN (almost LSTM) is used to find the parameters of a GMM in every time
step. While available RMDNs have been faced with different difficulties. The
most important of them is highdimensional problems. Since estimating the
covariance matrix for the highdimensional problems is more difficult, due to
existing correlation between dimensions and satisfying the positive definition
condition. Consequently, the available methods have usually used RMDN with a
diagonal covariance matrix for highdimensional problems by supposing
independence among dimensions. Hence, in this paper with inspiring a common
approach in the literature of GMM, we consider a tied configuration for each
precision matrix (inverse of the covariance matrix) in RMDN as (\(\Sigma _k^{
- 1} = U{D_k}U\)) to enrich GMM rather than considering a diagonal form for
it. But due to simplicity, we assume \(U\) be an Identity matrix and
\(D_k\) is a specific diagonal matrix for \(k^{th}\) component. Until now,
we only have a diagonal matrix and it does not differ with available diagonal
RMDNs. Besides, Flowbased neural networks are a new group of generative
models that are able to transform a distribution to a simpler distribution and
vice versa, through a sequence of invertible functions. Therefore, we applied a
diagonal GMM on transformed observations. At every time step, the next
observation, \({y_{t + 1}}\), has been passed through a flowbased neural
network to obtain a much simpler distribution. Experimental results for a
reinforcement learning problem verify the superiority of the proposed method to
the baseline method in terms of Negative LogLikelihood (NLL) for RMDN and
the cumulative reward for a controller with fewer population size
Synaptic mechanisms of interference in working memory
Information from preceding trials of cognitive tasks can bias performance in
the current trial, a phenomenon referred to as interference. Subjects
performing visual working memory tasks exhibit interference in their
trial-to-trial response correlations: the recalled target location in the
current trial is biased in the direction of the target presented on the
previous trial. We present modeling work that (a) develops a probabilistic
inference model of this history-dependent bias, and (b) links our probabilistic
model to computations of a recurrent network wherein short-term facilitation
accounts for the dynamics of the observed bias. Network connectivity is
reshaped dynamically during each trial, providing a mechanism for generating
predictions from prior trial observations. Applying timescale separation
methods, we can obtain a low-dimensional description of the trial-to-trial bias
based on the history of target locations. The model has response statistics
whose mean is centered at the true target location across many trials, typical
of such visual working memory tasks. Furthermore, we demonstrate task protocols
for which the plastic model performs better than a model with static
connectivity: repetitively presented targets are better retained in working
memory than targets drawn from uncorrelated sequences.Comment: 28 pages, 7 figure
Digging Deeper into Egocentric Gaze Prediction
This paper digs deeper into factors that influence egocentric gaze. Instead
of training deep models for this purpose in a blind manner, we propose to
inspect factors that contribute to gaze guidance during daily tasks. Bottom-up
saliency and optical flow are assessed versus strong spatial prior baselines.
Task-specific cues such as vanishing point, manipulation point, and hand
regions are analyzed as representatives of top-down information. We also look
into the contribution of these factors by investigating a simple recurrent
neural model for ego-centric gaze prediction. First, deep features are
extracted for all input video frames. Then, a gated recurrent unit is employed
to integrate information over time and to predict the next fixation. We also
propose an integrated model that combines the recurrent model with several
top-down and bottom-up cues. Extensive experiments over multiple datasets
reveal that (1) spatial biases are strong in egocentric videos, (2) bottom-up
saliency models perform poorly in predicting gaze and underperform spatial
biases, (3) deep features perform better compared to traditional features, (4)
as opposed to hand regions, the manipulation point is a strong influential cue
for gaze prediction, (5) combining the proposed recurrent model with bottom-up
cues, vanishing points and, in particular, manipulation point results in the
best gaze prediction accuracy over egocentric videos, (6) the knowledge
transfer works best for cases where the tasks or sequences are similar, and (7)
task and activity recognition can benefit from gaze prediction. Our findings
suggest that (1) there should be more emphasis on hand-object interaction and
(2) the egocentric vision community should consider larger datasets including
diverse stimuli and more subjects.Comment: presented at WACV 201
Dynamical laser spike processing
Novel materials and devices in photonics have the potential to revolutionize
optical information processing, beyond conventional binary-logic approaches.
Laser systems offer a rich repertoire of useful dynamical behaviors, including
the excitable dynamics also found in the time-resolved "spiking" of neurons.
Spiking reconciles the expressiveness and efficiency of analog processing with
the robustness and scalability of digital processing. We demonstrate that
graphene-coupled laser systems offer a unified low-level spike optical
processing paradigm that goes well beyond previously studied laser dynamics. We
show that this platform can simultaneously exhibit logic-level restoration,
cascadability and input-output isolation---fundamental challenges in optical
information processing. We also implement low-level spike-processing tasks that
are critical for higher level processing: temporal pattern detection and stable
recurrent memory. We study these properties in the context of a fiber laser
system, but the addition of graphene leads to a number of advantages which stem
from its unique properties, including high absorption and fast carrier
relaxation. These could lead to significant speed and efficiency improvements
in unconventional laser processing devices, and ongoing research on graphene
microfabrication promises compatibility with integrated laser platforms.Comment: 13 pages, 7 figure
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