Unsupervised cross-domain object detection transfers a detection model trained on a source domain to the target domain that has a different data distribution from the source domain. Conventional domain adaptation detection protocols need source domain data during adaptation. However, due to some reasons such as data security, privacy and storage, we cannot access the source data in many practical applications. In this paper, we focus on source-data free domain adaptive object detection, which uses the pre-trained source model instead of the source data for cross-domain adaptation. Due to the lack of source data, we cannot directly align domain distribution between domains. To challenge this, we propose the Source style transferred Mean Teacher (SMT) for source-data free Object Detection. The batch normalization layers in the pre-trained model contain the style information and the data distribution of the non-observed source data. Thus we use the batch normalization information from the pre-trained source model to transfer the target domain feature to the source-like style feature to make full use of the knowledge from the pre-trained source model. Meanwhile, we use the consistent regularization of the Mean Teacher to further distill the knowledge from the source domain to the target domain. Furthermore, we found that by adding perturbations associated with the target domain distribution, the model can increase the robustness of domain-specific information, thus making the learned model generalized to the target domain. Experiments on multiple domain adaptation object detection benchmarks verify that our method is able to achieve state-of-the-art performance.

For the text-to-image synthesis task, most discriminators in existing generative adversarial networks based methods tend to fall into a local suboptimal state too early in the training process, resulting in the poor quality of generated images. To address the above problems, a hybrid augmented loss discriminator is designed. In this designed discriminator, to reduce the sensitivity of the discriminator classification recognition, make it pay attention to the semantic and structural changes, we add the loss value of the fake sample to the loss value of the real sample. Moreover, to indirectly guide the generator to generate samples, the loss value of the real sample is added to the fake sample. The loss value mixed with real and fake samples actually augments signal transmission. It perturbs parameter update of the discriminator during optimization and prevents the discriminator from falling into the local suboptimal state prematurely. Whereafter, we apply the proposed discriminator to two kinds of text-to-image synthesis tasks. Experimental results show that the proposed method can help the baseline models to improve performance.

The current unsupervised cross-domain detection methods need source domain data to retrain the detection model in target domain. However, the source domain data may be unavailable due to privacy, decentralization, or computation resource restrictions. A natural idea is to optimize the parameters of the source domain model by self-supervised learning based on pseudo labels. We propose another approach from the viewpoint of noise perturbation without pseudo-labeling. It can be assumed that the source and target domains are actually derived from a domain invariant space through domain-specific perturbations, respectively. A super target domain can be constructed by augmenting more target domain perturbations to the target domain images. The optimal direction of the target domain to the domain invariant space can be approximated as the alignment direction from the super target domain to the target domain. Based on this idea, we propose a novel method called SOAP (SOurce data-free domain Adaptation through domain Perturbation) which can remove domain perturbation from the target domain. The image-level, instance-level, and category consistency regularizations based on Mean Teacher structure are proposed to learn the correct alignment direction. Specifically, the category consistency can also further improve the classification accuracy. Extensive experiments on multiple domain adaptation scenarios demonstrate that SOAP achieves better performance surpassing the baseline (Faster R-CNN) and multiple state-of-the-art domain adaptation methods which need to access source domain data.

Machine olfaction is an intelligent system that combines a cross-sensitivity chemical sensor array and an effective pattern recognition algorithm for the detection, identification, or quantification of various odors. Data collected by the sensor array are the multivariate time series signals with a complex structure, and these signals become more difficult to analyze due to sensor drift. In this work, we focus on improving the classification performance under sensor drift by using the deep learning method, which is popular nowadays. Compared with other methods, our method can effectively tackle sensor drift by automatically extracting features, thus not only removing the complexity of designing the hand-made features but also making it pervasive for a variety of application in machine olfaction. Our experimental results show that the deep learning method can learn the features that are more robust to drift than the original input and achieves high classification accuracy.

Graph regularized non-negative matrix factorization (NMF) algorithms can be applied to information retrieval, image processing, and pattern recognition. However, challenge that still remains is to prove the convergence of this class of learning algorithms since the geometrical structure of the data space is considered. This paper presents the convergence properties of the graph regularized NMF learning algorithms. In the analysis, we focus on the study of Euclidian distance based algorithms. The structures of the fixed points are presented. The non-divergence of the learning algorithms is analyzed by constructing invariant sets for update rules. Based on Lyapunov indirect method, the stability of the algorithms is discussed in detail. The analysis shows that this class of NMF algorithms can converge to their fixed points under some given conditions. In the simulations, theoretical results presented in the paper are confirmed. For different initializations and data sets, variations of cost functions and decomposition data in the learning are presented to show the convergence features of the discussed NMF update rules, and the convergence speed of the algorithms is also investigated.