102 research outputs found
Predicting Network Controllability Robustness: A Convolutional Neural Network Approach
Network controllability measures how well a networked system can be
controlled to a target state, and its robustness reflects how well the system
can maintain the controllability against malicious attacks by means of
node-removals or edge-removals. The measure of network controllability is
quantified by the number of external control inputs needed to recover or to
retain the controllability after the occurrence of an unexpected attack. The
measure of the network controllability robustness, on the other hand, is
quantified by a sequence of values that record the remaining controllability of
the network after a sequence of attacks. Traditionally, the controllability
robustness is determined by attack simulations, which is computationally time
consuming. In this paper, a method to predict the controllability robustness
based on machine learning using a convolutional neural network is proposed,
motivated by the observations that 1) there is no clear correlation between the
topological features and the controllability robustness of a general network,
2) the adjacency matrix of a network can be regarded as a gray-scale image, and
3) the convolutional neural network technique has proved successful in image
processing without human intervention. Under the new framework, a fairly large
number of training data generated by simulations are used to train a
convolutional neural network for predicting the controllability robustness
according to the input network-adjacency matrices, without performing
conventional attack simulations. Extensive experimental studies were carried
out, which demonstrate that the proposed framework for predicting
controllability robustness of different network configurations is accurate and
reliable with very low overheads.Comment: 11 pages, 7 figure
EFFECTS OF RUNNING FATIGUE ON KNEE JOINT SYMMETRY AMONG AMATEUR RUNNERS
The purpose of this study was to reveal the effects of running fatigue on the symmetry of lower limb dynamics and kinematics parameters. 18 male amateur runners participated in this study. The marker trajectories and ground reaction forces were collected via an 8-camera VICON and Kistler 3D force platform before and after the running-induced fatigue protocol. Symmetry angles (SA) of joint moments, range of motions (ROM), and joint stiffness in three planes were calculated pre- and post-fatigue. SA of knee Extension Angle, Internal rotation, Abduction moment, coronal ROM and joint stiffness significantly increased after fatigue(
PLANTAR FORCE COMPARISONS BETWEEN THE CHASSE STEP AND ONE STEP FOOTWORK DURING TOPSPIN FOREHAND USING STATISTICAL PARAMETRIC MAPPING
The purpose of this study was to investigate the plantar force characteristics of the chasse step and one step footwork during table tennis topspin stroke using one-dimensional statistical parameter mapping (SPM 1d). Twelve national players volunteered to participate in the study. The plantar force of the right foot during the chasse step and one step backward phase (BP) and forward phase (FP) was recorded by instrumented insole systems. Paired sample T tests in SPSS 24.0 (SPSSs Inc, Chicago, IL, USA) were used to analyze peak pressure of each plantar region. For SPM analysis, the plantar force time series curves were marked as a 100% process. A paired-samples T-test in MATLAB was used to analyze differences in plantar force. One step produced a greater plantar force than the chasse step during 6.92-11.22% BP (P=0.039). The chasse step produced a greater plantar force than one step during 53.47-99.01% BP (
Knowledge-Based Prediction of Network Controllability Robustness
Network controllability robustness reflects how well a networked system can
maintain its controllability against destructive attacks. Its measure is
quantified by a sequence of values that record the remaining controllability of
the network after a sequence of node-removal or edge-removal attacks.
Traditionally, the controllability robustness is studied only for directed
networks and is determined by attack simulations, which is computationally time
consuming or even infeasible. In the present paper, an improved method for
predicting the controllability robustness of undirected networks is developed
based on machine learning using a group of convolutional neural networks
(CNNs). In this scheme, a number of training data generated by simulations are
used to train the group of CNNs for classification and prediction,
respectively. Extensive experimental studies are carried out, which demonstrate
that 1) the proposed method predicts more precisely than the classical
single-CNN predictor; 2) the proposed CNN-based predictor provides a better
predictive measure than the traditional spectral measures and network
heterogeneity.Comment: 11 pages, 8 figures in Paper; 33 pages, 2 figures in Supplementary
Informatio
Improved production of docosahexaenoic acid in batch fermentation by newly-isolated strains of Schizochytrium sp. and Thraustochytriidae sp. through bioprocess optimization
Thraustochytrids, rich in docosahexaenoic acid (DHA, C22:6??3), represent a potential source of dietary fatty acids. Yet, the effect of culture conditions on growth and fatty acid composition vary widely among different thraustochytrid strains. Two different thraustochytrid strains, Schizochytrium sp. PKU#Mn4 and Thraustochytriidae sp. PKU#Mn16 were studied for their growth and DHA production characteristics under various culture conditions. Although they exhibited similar fatty acid profiles, PKU#Mn4 seemed a good candidate for industrial DHA fermentation while PKU#Mn16 displayed growth tolerance to a wide range of process conditions. Relative DHA content of 48.5% and 49.2% (relative to total fatty acids), respectively, were achieved on glycerol under their optimal flask culture conditions. Maximum DHA yield (Yp/x) of 21.0% and 18.9% and productivity of 27.6 mg/L-h and 31.9 mg/L-h were obtained, respectively, in 5-L bioreactor fermentation operated with optimal conditions and dual oxygen control strategy. A 3.4- and 2.8-fold improvement of DHA production (g/L), respectively, was achieved in this study. Overall, our study provides the potential of two thraustochytrid strains and their culture conditions for efficient production of DHA-rich oil
Deep Reinforcement Learning with Multitask Episodic Memory Based on Task-Conditioned Hypernetwork
Deep reinforcement learning algorithms are usually impeded by sampling
inefficiency, heavily depending on multiple interactions with the environment
to acquire accurate decision-making capabilities. In contrast, humans rely on
their hippocampus to retrieve relevant information from past experiences of
relevant tasks, which guides their decision-making when learning a new task,
rather than exclusively depending on environmental interactions. Nevertheless,
designing a hippocampus-like module for an agent to incorporate past
experiences into established reinforcement learning algorithms presents two
challenges. The first challenge involves selecting the most relevant past
experiences for the current task, and the second challenge is integrating such
experiences into the decision network. To address these challenges, we propose
a novel method that utilizes a retrieval network based on task-conditioned
hypernetwork, which adapts the retrieval network's parameters depending on the
task. At the same time, a dynamic modification mechanism enhances the
collaborative efforts between the retrieval and decision networks. We evaluate
the proposed method on the MiniGrid environment.The experimental results
demonstrate that our proposed method significantly outperforms strong
baselines
JARVIS-1: Open-World Multi-task Agents with Memory-Augmented Multimodal Language Models
Achieving human-like planning and control with multimodal observations in an
open world is a key milestone for more functional generalist agents. Existing
approaches can handle certain long-horizon tasks in an open world. However,
they still struggle when the number of open-world tasks could potentially be
infinite and lack the capability to progressively enhance task completion as
game time progresses. We introduce JARVIS-1, an open-world agent that can
perceive multimodal input (visual observations and human instructions),
generate sophisticated plans, and perform embodied control, all within the
popular yet challenging open-world Minecraft universe. Specifically, we develop
JARVIS-1 on top of pre-trained multimodal language models, which map visual
observations and textual instructions to plans. The plans will be ultimately
dispatched to the goal-conditioned controllers. We outfit JARVIS-1 with a
multimodal memory, which facilitates planning using both pre-trained knowledge
and its actual game survival experiences. JARVIS-1 is the existing most general
agent in Minecraft, capable of completing over 200 different tasks using
control and observation space similar to humans. These tasks range from
short-horizon tasks, e.g., "chopping trees" to long-horizon tasks, e.g.,
"obtaining a diamond pickaxe". JARVIS-1 performs exceptionally well in
short-horizon tasks, achieving nearly perfect performance. In the classic
long-term task of , JARVIS-1 surpasses the
reliability of current state-of-the-art agents by 5 times and can successfully
complete longer-horizon and more challenging tasks. The project page is
available at https://craftjarvis.org/JARVIS-1Comment: update project pag
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