Multimodal emotion recognition in conversational videos (ERC) develops rapidly in recent years. To fully extract the relative context from video clips, most studies build their models on the entire dialogues which make them lack of real-time ERC ability. Different from related researches, a novel multimodal emotion recognition model for conversational videos based on reinforcement learning and domain knowledge (ERLDK) is proposed in this paper. In ERLDK, the reinforcement learning algorithm is introduced to conduct real-time ERC with the occurrence of conversations. The collection of history utterances is composed as an emotion-pair which represents the multimodal context of the following utterance to be recognized. Dueling deep-Q-network (DDQN) based on gated recurrent unit (GRU) layers is designed to learn the correct action from the alternative emotion categories. Domain knowledge is extracted from public dataset based on the former information of emotion-pairs. The extracted domain knowledge is used to revise the results from the RL module and is transformed into other dataset to examine the rationality. The experimental results on datasets show that ERLDK achieves the state-of-the-art results on weighted average and most of the specific emotion categories.

Benefit from avoiding the utilization of labeled samples, which are usually insufficient in the real world, unsupervised learning has been regarded as a speedy and powerful strategy on clustering tasks. However, clustering directly from primal data sets leads to high computational cost, which limits its application on large-scale and high-dimensional problems. Recently, anchor-based theories are proposed to partly mitigate this problem and field naturally sparse affinity matrix, while it is still a challenge to get excellent performance along with high efficiency. To dispose of this issue, we first presented a fast semisupervised framework (FSSF) combined with a balanced $K$ -means-based hierarchical $K$ -means (BKHK) method and the bipartite graph theory. Thereafter, we proposed a fast self-supervised clustering method involved in this crucial semisupervised framework, in which all labels are inferred from a constructed bipartite graph with exactly $k$ connected components. The proposed method remarkably accelerates the general semisupervised learning through the anchor and consists of four significant parts: 1) obtaining the anchor set as interim through BKHK algorithm; 2) constructing the bipartite graph; 3) solving the self-supervised problem to construct a typical probability model with FSSF; and 4) selecting the most representative points regarding anchors from BKHK as an interim and conducting label propagation. The experimental results on toy examples and benchmark data sets have demonstrated that the proposed method outperforms other approaches.

Fusion of multimodal features is a momentous problem for video emotion recognition. As the development of deep learning, directly fusing feature matrixes of each mode through neural networks at feature level becomes mainstream method. However, unlike unimodal issues, for multimodal analysis, finding the correlations between different modal is as important as discovering effective unimodal features. To make up the deficiency in unearthing the intrinsic relationships between multimodal, a novel modularized multimodal emotion recognition model based on deep canonical correlation analysis (MERDCCA) is proposed in this letter. In MERDCCA, four utterances are gathered as a new group and each utterance contains text, audio and visual information as multimodal input. Gated recurrent unit layers are used to extract the unimodal features. Deep canonical correlation analysis based on encoder-decoder network is designed to extract cross-modal correlations by maximizing the relevance between multimodal. The experiments on two public datasets show that MERDCCA achieves the better results.

As a significant and fundamental task in the remote sensing field, object detection has received increasing attention and research studies. However, geospatial object detection is still a challenge owing to the dramatic variation in object scales, intraclass differences, and interclass similarity from multiscale and multiclass objects. To deal with these problems, an end-to-end feature-reflowing pyramid network (FRPNet) is proposed in this letter. FRPNet has two advantages that contribute to improve object detection accuracy. First, we embed a nonlocal block into the backbone in order to get the relevancy between different regions of the geospatial image for obtaining discriminative features. Furthermore, a feature-reflowing pyramid structure is proposed to generate high-quality feature presentation for each scale through fusing fine-grained features from the adjacent lower level, which improves the detection capability for multiscale and multiclass objects. Experiments on a public remote sensing data set DIOR illustrate that FRPNet can significantly improve the performance when compared to several state-of-the-art detection approaches in terms of mean average precision (mAP).

Embedded feature selection approach guides subsequent projection matrix (selection matrix) learning through the acquisition of pseudolabel matrix to conduct feature selection tasks. Yet the continuous pseudolabel matrix learned from relaxed problem based on spectral analysis deviates from reality to some extent. To cope with this issue, we design an efficient feature selection framework inspired by classical least-squares regression (LSR) and discriminative K-means (DisK-means), which is called the fast sparse discriminative K-means (FSDK) for the feature selection method. First, the weighted pseudolabel matrix with discrete trait is introduced to avoid trivial solution from unsupervised LSR. On this condition, any constraint imposed into pseudolabel matrix and selection matrix is dispensable, which is significantly beneficial to simplify the combinational optimization problem. Second, the $\ell_{2,p}$ -norm regularizer is introduced to satisfy the row sparsity of selection matrix with flexible $p$ . Consequently, the proposed FSDK model can be treated as a novel feature selection framework integrated from the DisK-means algorithm and $\ell_{2,p}$ -norm regularizer to optimize the sparse regression problem. Moreover, our model is linearly correlated with the number of samples, which is speedy to handle the large-scale data. Comprehensive tests on various data terminally illuminate the effectiveness and efficiency of FSDK.

With practical applications such as environment surveillance, agricultural production, and disaster assessment, accurate object detection in remote sensing images is in high demand. Precise detection of object instances in remote sensing images remains considerably challenging due to dense instance stacking, large-scale variations, and complex backgrounds. To solve the mentioned issues, a novel global context-weaving network (GCWNet) is developed for object detection in remote sensing images. We propose two novel modules for feature extraction and refinement, which include the global context aggregation module (GCAM) and the feature refinement module (FRM). GCAM assembles a global context with high-level and low-level features through feature weaving, which facilitates dense object detection. Meanwhile, FRM convolves multiple receptive fields by combining different branches, thereby further refining the features and improving the feature distinction at different scales. Furthermore, we design to alleviate the sample imbalanced problem during training using focal loss and balanced L1 loss to improve object classification and regression, respectively. The experimental results indicate that GCWNet achieves superior performance in object classification and localization on the DOTA-v1.5 dataset, which illustrates the superiority of GCWNet.