Hawkes processes have recently risen to the forefront of tools when it comes to modeling and generating sequential events data. Multidimensional Hawkes processes model both the self and cross-excitation between different types of events and have been applied successfully in various domain such as finance, epidemiology and personalized recommendations, among others. In this work we present an adaptation of the Frank-Wolfe algorithm for learning multidimensional Hawkes processes. Experimental results show that our approach has better or on par accuracy in terms of parameter estimation than other first order methods, while enjoying a significantly faster runtime.

Forecasts by the European Centre for Medium-Range Weather Forecasts (ECMWF; EC for short) can provide a basis for the establishment of maritime-disaster warning systems, but they contain some systematic biases.The fifth-generation EC atmospheric reanalysis (ERA5) data have high accuracy, but are delayed by about 5 days. To overcome this issue, a spatiotemporal deep-learning method could be used for nonlinear mapping between EC and ERA5 data, which would improve the quality of EC wind forecast data in real time. In this study, we developed the Multi-Task-Double Encoder Trajectory Gated Recurrent Unit (MT-DETrajGRU) model, which uses an improved double-encoder forecaster architecture to model the spatiotemporal sequence of the U and V components of the wind field; we designed a multi-task learning loss function to correct wind speed and wind direction simultaneously using only one model. The study area was the western North Pacific (WNP), and real-time rolling bias corrections were made for 10-day wind-field forecasts released by the EC between December 2020 and November 2021, divided into four seasons. Compared with the original EC forecasts, after correction using the MT-DETrajGRU model the wind speed and wind direction biases in the four seasons were reduced by 8-11% and 9-14%, respectively. In addition, the proposed method modelled the data uniformly under different weather conditions. The correction performance under normal and typhoon conditions was comparable, indicating that the data-driven mode constructed here is robust and generalizable.

Previous work on action representation learning focused on global representations for short video clips. In contrast, many practical applications, such as video alignment, strongly demand learning the intensive representation of long videos. In this paper, we introduce a new framework of contrastive action representation learning (CARL) to learn frame-wise action representation in a self-supervised or weakly-supervised manner, especially for long videos. Specifically, we introduce a simple but effective video encoder that considers both spatial and temporal context by combining convolution and transformer. Inspired by the recent massive progress in self-supervised learning, we propose a new sequence contrast loss (SCL) applied to two related views obtained by expanding a series of spatio-temporal data in two versions. One is the self-supervised version that optimizes embedding space by minimizing KL-divergence between sequence similarity of two augmented views and prior Gaussian distribution of timestamp distance. The other is the weakly-supervised version that builds more sample pairs among videos using video-level labels by dynamic time wrapping (DTW). Experiments on FineGym, PennAction, and Pouring datasets show that our method outperforms previous state-of-the-art by a large margin for downstream fine-grained action classification and even faster inference. Surprisingly, although without training on paired videos like in previous works, our self-supervised version also shows outstanding performance in video alignment and fine-grained frame retrieval tasks.

本文提出了一个紧凑的系统OpenPneu，以支持软机器人多腔的气动驱动。系统中使用微型泵来生成气流，因此不需要额外的输入，因为需要压缩空气。我们的系统执行模块化设计以提供良好的可扩展性，这已在具有十个空气通道的原型上证明。OpenPNEU的每个空气通道都配备了通货膨胀和通气功能，可提供从正到负的全范围压力供应，最大流速为1.7 L/min。我们的系统内置了对压力的高精度闭环控制，以实现稳定而有效的动态性能。提供了Python中的开源控制接口和API。我们还证明了OpenPneu在三个软机器人系统上的功能，最多10个腔室。

在本文中，我们介绍了一个数据驱动的框架，以优化软抓地力的平面外刚度，以实现机械性能，如难以扭动且易于弯曲。在软气动弯曲执行器（SPBA）的设计中证明了该方法的有效性。首先，定义了一个新的目标函数来定量评估平面外刚度以及弯曲性能。然后，对SPBA设计的参数模型进行灵敏度分析，以确定有限元分析（FEA）的优化设计参数。为了启用数值优化的计算，采用数据驱动的方法来学习成本函数，该成本函数直接代表平面外刚度作为设计变量的可区分函数。一种基于梯度的方法用于最大化SPBA的平面外刚度，同时确保特定的弯曲性能。我们方法的有效性已在3D打印的握把上进行的物理实验中得到了证明。

大多数现有的神经体系结构搜索（NAS）基准和算法优先考虑了良好的任务，例如CIFAR或Imagenet上的图像分类。这使得在更多样化的领域的NAS方法的表现知之甚少。在本文中，我们提出了NAS-Bench-360，这是一套基准套件，用于评估超出建筑搜索传统研究的域的方法，并使用它来解决以下问题：最先进的NAS方法在多样化的任务？为了构建基准测试，我们策划了十个任务，这些任务涵盖了各种应用程序域，数据集大小，问题维度和学习目标。小心地选择每个任务与现代CNN的搜索方法互操作，同时可能与其原始开发领域相距遥远。为了加快NAS研究的成本，对于其中两个任务，我们发布了包括标准CNN搜索空间的15,625个体系结构的预定性能。在实验上，我们表明需要对NAS BENCH-360进行更强大的NAS评估，从而表明几种现代NAS程序在这十个任务中执行不一致，并且有许多灾难性差的结果。我们还展示了NAS Bench-360及其相关的预算结果将如何通过测试NAS文献中最近推广的一些假设来实现未来的科学发现。 NAS-Bench-360托管在https://nb360.ml.cmu.edu上。

调整Quand参数是机器学习管道的重要而艰巨的部分。在联合学习中，封锁率优化更具挑战性，在多均匀设备的分布式网络上学习模型;在这里，需要保留设备上的数据并执行本地培训使得难以有效地培训和评估配置。在这项工作中，我们调查联邦封面调整的问题。我们首先识别关键挑战，并展示标准方法如何适应联合环境的基线。然后，通过与重量共享的神经结构搜索技术进行新颖的连接，我们介绍了一种新的方法，联邦快递，以加速联合的超参数调整，该调整适用于广泛使用的联合优化方法，例如FADVG和最近的变体。从理论上讲，我们表明联邦快递器在跨设备的在线凸优化的设置中正确调整了在设备上的学习速率。凭经验，我们表明，联邦快递可以在莎士比亚，春头和CIFAR-10基准上的几个百分点占据联邦封面调整的自然基线，使用相同的培训预算获得更高的准确性。

Compressed videos often exhibit visually annoying artifacts, known as Perceivable Encoding Artifacts (PEAs), which dramatically degrade video visual quality. Subjective and objective measures capable of identifying and quantifying various types of PEAs are critical in improving visual quality. In this paper, we investigate the influence of four spatial PEAs (i.e. blurring, blocking, bleeding, and ringing) and two temporal PEAs (i.e. flickering and floating) on video quality. For spatial artifacts, we propose a visual saliency model with a low computational cost and higher consistency with human visual perception. In terms of temporal artifacts, self-attention based TimeSFormer is improved to detect temporal artifacts. Based on the six types of PEAs, a quality metric called Saliency-Aware Spatio-Temporal Artifacts Measurement (SSTAM) is proposed. Experimental results demonstrate that the proposed method outperforms state-of-the-art metrics. We believe that SSTAM will be beneficial for optimizing video coding techniques.

As one of the most important psychic stress reactions, micro-expressions (MEs), are spontaneous and transient facial expressions that can reveal the genuine emotions of human beings. Thus, recognizing MEs (MER) automatically is becoming increasingly crucial in the field of affective computing, and provides essential technical support in lie detection, psychological analysis and other areas. However, the lack of abundant ME data seriously restricts the development of cutting-edge data-driven MER models. Despite the recent efforts of several spontaneous ME datasets to alleviate this problem, it is still a tiny amount of work. To solve the problem of ME data hunger, we construct a dynamic spontaneous ME dataset with the largest current ME data scale, called DFME (Dynamic Facial Micro-expressions), which includes 7,526 well-labeled ME videos induced by 671 participants and annotated by more than 20 annotators throughout three years. Afterwards, we adopt four classical spatiotemporal feature learning models on DFME to perform MER experiments to objectively verify the validity of DFME dataset. In addition, we explore different solutions to the class imbalance and key-frame sequence sampling problems in dynamic MER respectively on DFME, so as to provide a valuable reference for future research. The comprehensive experimental results show that our DFME dataset can facilitate the research of automatic MER, and provide a new benchmark for MER. DFME will be published via https://mea-lab-421.github.io.

Face Anti-spoofing (FAS) is essential to secure face recognition systems from various physical attacks. However, recent research generally focuses on short-distance applications (i.e., phone unlocking) while lacking consideration of long-distance scenes (i.e., surveillance security checks). In order to promote relevant research and fill this gap in the community, we collect a large-scale Surveillance High-Fidelity Mask (SuHiFiMask) dataset captured under 40 surveillance scenes, which has 101 subjects from different age groups with 232 3D attacks (high-fidelity masks), 200 2D attacks (posters, portraits, and screens), and 2 adversarial attacks. In this scene, low image resolution and noise interference are new challenges faced in surveillance FAS. Together with the SuHiFiMask dataset, we propose a Contrastive Quality-Invariance Learning (CQIL) network to alleviate the performance degradation caused by image quality from three aspects: (1) An Image Quality Variable module (IQV) is introduced to recover image information associated with discrimination by combining the super-resolution network. (2) Using generated sample pairs to simulate quality variance distributions to help contrastive learning strategies obtain robust feature representation under quality variation. (3) A Separate Quality Network (SQN) is designed to learn discriminative features independent of image quality. Finally, a large number of experiments verify the quality of the SuHiFiMask dataset and the superiority of the proposed CQIL.