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In the era of deep learning, it's important to obtain enough qualified data for model training. For the labor-intensive and time-consuming characteristics of data collection and annotation, date augmentation has been widely employed in deep learning methods to mitigate over-fitting. It has been proven to be one of the most effective ways to ensure the performance of deep models. In the field of computer vision, the principal goal of data augmentation usually is enlarging both the scale and diversity of the dataset, and maintaining the quality of both the image and the annotation data simultaneously. Data augmentation methods at the raw input data level are intuitive to obtain semantic meaningful images. In this paper, we provide a brief survey on some data augmentation studies conducted at image level and briefly categorize the studies into two main classes: those based on image editing and those based on image generation. We also make an analysis of the semantic-preserving considerations within data augmentation techniques. [ABSTRACT FROM AUTHOR]

Celsian was synthesized in situ and was used to sinter silicon carbide. The low temperature pressureless liquid sintering process for BAS/SiC complex phase ceramics was studied, and ceramic materials with high density were prepared. The effect of sintering temperature and content of BAS on density, structure and mechanical properties of the ceramics were investigated. The densification and microstructures of BAS/SiC ceramics were observed by scanning electron microscope. The crystalline phase of the composite ceramics was identified by X-ray powder diffraction. The results show that celsian is synthesized at the temperature of 1800 ℃, and BAS/SiC ceramics are prepared with density of 3.2 g/cm3. BAS is precipitated in hexagonal structure, and SiC particles are distributed uniformly in the composite ceramic. The flexural strength and fracture toughness of composite ceramics are decreased due to grains growth while the sintering temperature is above 1800 ℃. When the mass content of BAS reaches 30%, the typical flexural strength, elastic modulus and fracture toughness of the pressureless sintered BAS/SiC ceramics are 413 MPa, 210 GPa and 5.03 MPa?m1/2 at room temperature.

Video captioning is a joint task of computer vision and natural language processing, which aims to describe the video content using several natural language sentences. Nowadays, most methods cast this task as a mapping problem, which learns a mapping from visual features to natural language and generates captions directly from videos. However, the underlying challenge of video captioning, i.e., sequence to sequence mapping across the different domains, is still not well handled. To address these problems, we introduce the polishing mechanism in an attempt to mimic human polishing process and propose a generate-and-polish framework for video captioning. In this paper, we propose a two-step transformer based polishing network (TSTPN) consisting of two sub-modules: the generation-module is to generate the caption candidate and the polishing-module is to gradually refine the generated candidate. Specifically, the candidate provides a global information of the visual contents in a semantically-meaningful order, where it is firstly considered as a semantic intersnubber to bridge the semantic gap between the text and video, with the cross-modal attention mechanism for better cross-modal modeling; and it secondly provides a global planning ability to maintain the semantic consistency and fluency of the whole sentence for better sequence mapping. In experiments, we present adequate evaluations to show that the proposed TSTPN achieves the comparable and even better performance than the state-of-the-art methods on the benchmark datasets. [ABSTRACT FROM AUTHOR]

Labanotation is a symbolic recording system for human movements, and also a powerful tool for protecting and spreading folk dances and other performing arts. State-of-the-art automatic Labanotation uses end-to-end methods with sequence-based skeleton representation, which cannot capture the relationship between joints and bones in the skeleton for accurate descriptions of continuous lower limb movements such as dance steps. In this paper, we propose a novel double-stream fusion method of directed graph neural networks (DGNN), combined with connectionist temporal classification (CTC), namely DFGNN-CTC, for sequential fine-grained motion recognition, such as the Labanotation generation of unsegmented dance movement. First, we extract double-stream directed graph feature, employing an orientation-normalized directed acyclic graph (ON-DAG) and an orientation-normalized temporal directed acyclic graph (ON-TDAG), to jointly model spatiotemporal properties of movement recorded in motion capture data. Then, we design a CTC-based fusion-pooling module to fuse the spatial and temporal streams encoded by two DGNNs. It concatenates and fuses the two streams to generate discriminative descriptions of each time step, and concentrates them to make per-time-step predictions of Laban gesture type, from which the CTC searches the optimal Laban symbol sequence, corresponding to elemental motions composing the movement. In this way, the new method enables much finer discrimination for similar Laban gestures with subtle differences in spatial and temporal properties through joint contextual spatiotemporal modeling so that it achieves much superior performance in continuous Labanotation generation to existing methods, which only have single-stream analysis either spatially or temporally. The experiments on two Labanotation-labelled motion capture datasets demonstrate the effectiveness of the components in the proposed method and its superiority comparing with the state-of-the-art methods, especially for lower limb movements. [ABSTRACT FROM AUTHOR]

Human activity localization aims at recognizing contents and detecting locations of activities in video sequences. With an increasing number of untrimmed video data, traditional activity localization methods always suffer from two major limitations. First, detailed annotations are needed in most existing methods, i.e., bounding-box annotations in every frame, which are both expensive and time consuming. Second, the search space is too large for 3D activity localization, which requires generating a large number of proposals. In this paper, we propose a unified deep Q-network with weak reward and weak loss (DWRLQN) to address the two problems. Certain weak knowledge and weak constraints involving the temporal dynamics of human activity are incorporated into a deep reinforcement learning framework under sparse spatial supervision, where we assume that only a portion of frames are annotated in each video sequence. Experiments on UCF-Sports, UCF-101 and sub-JHMDB demonstrate that our proposed model achieves promising performance by only utilizing a very small number of proposals. More importantly, our DWRLQN trained with partial annotations and weak information even outperforms fully supervised methods. [ABSTRACT FROM AUTHOR]

Remote sensing (RS) scene classification plays an important role in the field of earth observation. With the rapid development of the RS techniques, a large number of RS scene images are available. As manually labeling large-scale RS scene images is both labor and time consuming, when a new unlabeled data set is obtained, how to use the existing labeled data sets to classify the new unlabeled images is an important research direction. Different RS scene image data sets may be taken from different type of sensors, and the images may vary from imaging modalities, spatial resolutions, and image scales, so the distribution discrepancy exists among different image data sets. As a result, simply applying convolutional neural networks (CNN) trained on source domain cannot accurately classify the images on target domain. Domain adaptation (DA) can be helpful to solve this problem. In this letter, we design a subspace alignment (SA) and CNN-based framework to solve the DA problem in RS scene image classification. A new SA layer is proposed and added into CNN models for DA, which could align the source and target domains in some feature subspace. Fine-tuning the modified CNN model with the added SA layer makes the CNN model adapt to the aligned feature subspace and helps to relieve the domain distribution discrepancy. The experiments conducted on two public data sets show that adding the SA layer into CNN improves the scene classification on the target domain. [ABSTRACT FROM AUTHOR]

MgAl2O4 spinel powders were first applied for aluminum dihydrogen phosphate hydrosol curing reaction. The solidification of spinel powders to phosphate hydrosol was studied in middle and low temperature condition. Besides, composites were prepared with quartz textile as reinforcing part, aluminum hydrogen phosphate hydrosol as matrix and spinel MgAl2O4 as firming agent. Curing temperature of phosphate hydrosol and the additive content of spinel MgAl2O4 powders were measured by thermogravimetric analysis and differential scanning calorimeter. At the same time, the crystalline phase of curing products was identified by X-ray powders diffraction. Microstructures of the composites were observed by scanning electron microscope. Moreover, the mechanical and resistant moisture absorption properties of phosphate composites were investigated. The results showed that aluminum dihydrogen phosphate resin had occurred dehydration reaction and formed into cross-linkage net in the temperature near to 170 °C, while the resin was added spinel MgAl2O4 powders. And it was contributed to reduce original pores and flaws in the matrix with mild reaction process. Owing to the promoting effect of spinel, the mainly reaction products were aluminum phosphate with the style of quartz and magnesium phosphate with monoclinic structure. Meanwhile, the reaction that aluminum dihydrogen phosphate changed into aluminum polyphosphate was prevented, which was benefit to enhance the resistant moisture absorption property of the composite. When the content of spinel MgAl2O4 powders arrived at 18wt%, the composite obtained the highest properties, which the flexual strength at room temperature and at 800 °C were about 165 MPa and 75 MPa. And dielectric properties of the composite were remained stably during long time storage, which dielectric constant was about 3.5 to 3.6 and loss tangent was less than 0.01 at room temperature respectively. [ABSTRACT FROM AUTHOR]

Abstract Locating human action in spatio-temporal domain among untrimmed videos is an important but challenging task. Recent works have shown that incorporating contextual information leads to a significant improvement in action recognition, but there is still no existing work taking full advantage of context for action localization. While the popular target-centered methods have achieved promising results, they fail to exploit contexts and capture temporal dynamics in actions. In this paper, we propose a principled dynamic model, called spatio-temporal context model (STCM), to simultaneously locate and recognize actions. The STCM integrates various kinds of contexts, including the temporal context that consists of the sequences before and after action as well as the spatial context in the surrounding of target. Meanwhile, a novel dynamic programming approach is introduced to accumulate evidences collected at a small set of candidates in order to detect the spatio-temporal location of action effectively and efficiently. We report encouraging results on the UCF-Sports and UCF-101. It demonstrates that the contextual information is not only helpful for action recognition, but also contributes to action localization. [ABSTRACT FROM AUTHOR]

Labanotation is one of the most widely used notation systems and plays a powerful role in recording and archiving traditional folk dance. We propose an end-to-end method for generating Labanotation from motion capture data by identifying the movement of each part of the human body and by assigning corresponding Labanotation symbols. Our method is mainly highlighted in the following aspects: first, we design simple yet highly discriminative skeleton features that can accurately represent human movements; and second, for the recognition of upper limb movements, we adopt fast and efficient extreme-learning neural networks, and for the recognition of lower limb movements, we employ powerful long short-term memory networks. It is worth mentioning that this is the first time that neural networks have been applied to the field of Labanotation generation. Experimental results show that our approach achieves much better recognition accuracy than previous work. © 2019 SPIE and IS&T [DOI: 10.1117/1.JEI.28.2.023026] [ABSTRACT FROM AUTHOR]

Zero-shot learning (ZSL) has recently attracted increasing attention in visual tasks like action recognition. We propose a spatiotemporal visual-semantic embedding network (STVSEM) for zero-shot action recognition. First, given the fact that two-stream architecture based action recognition algorithms have achieved excellent results in recent years, the module is assembled to our designed network by simultaneously using the spatial features (e.g., RGB appearance) and optical flow in time domain as visual features to significantly improve the visual expression capability. Then, in order to slightly alleviate the problem of semantic loss that typically occurs in the case of using embedding-based ZSL methods, an autoencoder is introduced to get a better semantic representation and complement semantic relationship information for unseen classes by seen classes. Last but not least, a joint embedding mechanism that explores and exploits the relationships of the visual data and semantic information in an intermediate space is employed to ameliorate the gap between vision and semantics. The experimental results on Charades and UCF101 datasets indicate that the proposed method outperforms the state-of-the-art methods in accuracy, which further demonstrates the effectiveness of our method. [ABSTRACT FROM AUTHOR]

Video denoising is a low-level task that uses the information of neighbor frames to denoise polluted frames. Using the information provided by neighboring frames, noise can be effectively removed and the denoising effect is improved. Through continuous development, single-stage and multi-stage denoising methods have been proposed. However, these existing denoising methods simply use the information provided by neighbor frames to denoise the polluted frames, paying insufficient attention to the polluted frames and making insufficient use of the information of the polluted frames. We propose a two-stage video denoising network called multiple forward-backward strategies for two-stage video denoising, which improves the denoising performance and retains more detailed information by enhancing the utilization of information of polluted frames. Extensive experiments have been conducted, and the experimental results show that the proposed method outperforms the state-of-the-art denoising methods in both qualitative and quantitative comparisons. [ABSTRACT FROM AUTHOR]

In this paper, we propose an algorithm of anomaly detection in crowded scenes by using sparse representation over the normal bases. First, the histogram of maximal optical flow projection (HMOFP) features are extracted from a set of normal training data. Then, the online dictionary learning algorithm is used to train an optimal dictionary with proper redundancy, which is better than the dictionary simply composed by the HMOFP features of the whole training data. In order to detect the normalness of a frame, the l -norm of the sparse reconstruction coefficients is used as the Reconstruction Coefficient Sparsity (RCS). Our algorithm is effective for both global abnormal events (GAE) and local abnormal events (LAE). We evaluate our method on three benchmark datasets-the UMN dataset, the PETS2009 dataset and the UCSD Ped1 dataset. Compared with the most popular methods, experimental results show that our algorithm achieves good results especially for the pixel-level local abnormal event localization. [ABSTRACT FROM AUTHOR]

Real-time object tracking has wide applications in time-critical multimedia processing areas such as motion analysis and human–computer interaction. It remains a hard problem to balance between accuracy and speed. In this paper, we present a fast real-time context-based visual tracking algorithm with a new saliency prior context (SPC) model. Based on the probability formulation, the tracking problem is solved by sequentially maximizing the computed confidence map of target location in each video frame. To handle the various cases of feature distributions generated from different targets and their contexts, we exploit low-level features as well as fast spectral analysis for saliency to build a new prior context model. Then, based on this model and a spatial context model learned online, a confidence map is computed and the target location is estimated. In addition, under this framework, the tracking procedure can be accelerated by the fast Fourier transform. Therefore, the new method generally achieves a real-time running speed. Extensive experiments show that our tracking algorithm based on the proposed SPC model achieves real-time computation efficiency with overall best performance comparing with other state-of-the-art methods. [ABSTRACT FROM PUBLISHER]

As a major research field in computer vision, automatic generation of Labanotation has been attracting the attention of many researchers. These researchers use various methods to engage in dance education and protection, but the existing methods do not consider the spatial-temporal dependence modeling of dance movements. Therefore, they do not represent complex dance movements optimally. We propose an automatic generation network of Labanotation based on the long and short spatial-temporal relations. It includes local spatial-temporal feature extraction network, global spatial-temporal feature extraction network, and local and global feature fusion network. It can align the input and output sequences while modeling the skeletal spatial-temporal relation. The local spatial-temporal features among short interval skeleton sequence relationship are obtained through the multi-scale convolution of time and space. The global spatial-temporal features are learned through the transformer network to obtain the relationship among skeleton sequences with long interval. For the output of the two networks, we use the pyramid squeeze attention network to exchange information in long and short spatial-temporal information, achieving complementarity to improve the accuracy of action recognition. Experimental results show that the proposed method outperforms the state-of-the-art methods on laban16 and laban48, which are common datasets for the research of Labanotation. [ABSTRACT FROM AUTHOR]