24,716 research outputs found
Epidemic modelling by ripple-spreading network and genetic algorithm
Mathematical analysis and modelling is central to infectious disease epidemiology. This paper, inspired by the natural ripple-spreading phenomenon, proposes a novel ripple-spreading network model for the study of infectious disease transmission. The new epidemic model naturally has good potential for capturing many spatial and temporal features observed in the outbreak of plagues. In particular, using a stochastic ripple-spreading process simulates the effect of random contacts and movements of individuals on the probability of infection well, which is usually a challenging issue in epidemic modeling. Some ripple-spreading related parameters such as threshold and amplifying factor of nodes are ideal to describe the importance of individuals’ physical fitness and immunity. The new model is rich in parameters to incorporate many real factors such as public health service and policies, and it is highly flexible to modifications. A genetic algorithm is used to tune the parameters of the model by referring to historic data of an epidemic. The well-tuned model can then be used for analyzing and forecasting purposes. The effectiveness of the proposed method is illustrated by simulation results
Transfer learning for time series classification
Transfer learning for deep neural networks is the process of first training a
base network on a source dataset, and then transferring the learned features
(the network's weights) to a second network to be trained on a target dataset.
This idea has been shown to improve deep neural network's generalization
capabilities in many computer vision tasks such as image recognition and object
localization. Apart from these applications, deep Convolutional Neural Networks
(CNNs) have also recently gained popularity in the Time Series Classification
(TSC) community. However, unlike for image recognition problems, transfer
learning techniques have not yet been investigated thoroughly for the TSC task.
This is surprising as the accuracy of deep learning models for TSC could
potentially be improved if the model is fine-tuned from a pre-trained neural
network instead of training it from scratch. In this paper, we fill this gap by
investigating how to transfer deep CNNs for the TSC task. To evaluate the
potential of transfer learning, we performed extensive experiments using the
UCR archive which is the largest publicly available TSC benchmark containing 85
datasets. For each dataset in the archive, we pre-trained a model and then
fine-tuned it on the other datasets resulting in 7140 different deep neural
networks. These experiments revealed that transfer learning can improve or
degrade the model's predictions depending on the dataset used for transfer.
Therefore, in an effort to predict the best source dataset for a given target
dataset, we propose a new method relying on Dynamic Time Warping to measure
inter-datasets similarities. We describe how our method can guide the transfer
to choose the best source dataset leading to an improvement in accuracy on 71
out of 85 datasets.Comment: Accepted at IEEE International Conference on Big Data 201
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