Solar activity is usually caused by the evolution of solar magnetic fields. Magnetic field parameters derived from photospheric vector magnetograms of solar active regions have been used to analyze and forecast eruptive events such as solar flares and coronal mass ejections. Unfortunately, the most recent solar cycle 24 was relatively weak with few large flares, though it is the only solar cycle in which consistent time-sequence vector magnetograms have been available through the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) since its launch in 2010. In this paper, we look into another major instrument, namely the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) from 1996 to 2010. The data archive of SOHO/MDI covers more active solar cycle 23 with many large flares. However, SOHO/MDI data only has line-of-sight (LOS) magnetograms. We propose a new deep learning method, named MagNet, to learn from combined LOS magnetograms, Bx and By taken by SDO/HMI along with H-alpha observations collected by the Big Bear Solar Observatory (BBSO), and to generate vector components Bx' and By', which would form vector magnetograms with observed LOS data. In this way, we can expand the availability of vector magnetograms to the period from 1996 to present. Experimental results demonstrate the good performance of the proposed method. To our knowledge, this is the first time that deep learning has been used to generate photospheric vector magnetograms of solar active regions for SOHO/MDI using SDO/HMI and H-alpha data.
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太阳耀斑,尤其是M级和X级耀斑,通常与冠状质量弹出(CMES)有关。它们是太空天气影响的最重要来源,可能会严重影响近地环境。因此,必须预测耀斑(尤其是X级),以减轻其破坏性和危险后果。在这里,我们介绍了几种统计和机器学习方法,以预测AR的耀斑指数(FI),这些方法通过考虑到一定时间间隔内的不同类耀斑的数量来量化AR的耀斑生产力。具体而言,我们的样本包括2010年5月至2017年12月在太阳能磁盘上出现的563个AR。25个磁性参数,由空中震动和磁性成像器(HMI)的太空天气HMI活性区域(Sharp)提供的太阳能动力学观测值(HMI)。 (SDO),表征了代理中存储在ARS中的冠状磁能,并用作预测因子。我们研究了这些尖锐的参数与ARS的FI与机器学习算法(样条回归)和重采样方法(合成少数群体过度采样技术,用于使用高斯噪声回归的合成少数群体过度采样技术,smogn简短)。基于既定关系,我们能够在接下来的1天内预测给定AR的FIS值。与其他4种流行的机器学习算法相比,我们的方法提高了FI预测的准确性,尤其是对于大型FI。此外,我们根据Borda Count方法从由9种不同的机器学习方法渲染的等级计算出尖锐参数的重要性。
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智能对话代理人和人类之间互动的承诺是,模型可以从这种反馈中学习以改进。不幸的是,野外的这种交流并不总是涉及良性或高质量的人类话语,并将包括订婚的(助手),未接触甚至恶意用户(巨魔)的混合。在这项工作中,我们研究了如何在这种环境中进行强大的学习。我们引入了基准评估,即Safetymix,可以评估在各种对抗环境中学习安全语言与有毒语言的方法,以测试其稳健性。我们建议和分析几种缓解学习算法,这些算法在示例或用户级别上识别巨魔。我们的主要发现是,基于用户的方法考虑到巨魔用户将在多个示例中表现出对抗性行为,在我们的基准测试中的各种环境中都可以使用。然后,我们在部署期间收集的对话的进一步现实生活中测试这些方法,结果相似。
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我们提出了Blenderbot 3,这是一个175B参数对话模型,能够通过访问Internet和长期内存进行开放域对话,并接受了大量用户定义的任务的培训。我们同时发布了模型权重和代码,还将模型部署在公共网页上,以与有机用户进行交互。该技术报告描述了该模型的构建方式(建筑,模型和培训计划)以及其部署的细节,包括安全机制。人类评估表明,它优于现有的开放域对话代理,包括其前身(Roller等,2021; Komeili等,2022)。最后,我们使用部署收集的数据详细介绍了持续学习的计划,该数据也将公开发布。因此,该研究计划的目标是使社区能够研究通过互动学习的不断改进的负责任的代理商。
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半监控视频动作识别倾向于使深神经网络能够实现显着性能,即使具有非常有限的标记数据。然而,现有方法主要从当前的基于图像的方法转移(例如,FixMatch)。不具体利用时间动态和固有的多模式属性,它们的结果可能是次优。为了更好地利用视频中的编码的时间信息,我们将时间梯度引入了本文中的更多细小特征提取的额外模态。具体而言,我们的方法明确地蒸馏从时间梯度(TG)的细粒度运动表示,并施加不同方式的一致性(即RGB和TG)。在推理期间,没有额外的计算或参数,在没有额外的计算或参数的情况下显着提高了半监督动作识别的性能。我们的方法在若干典型的半监督设置(即标记数据的不同比率)下实现三个视频动作识别基准(即动态-400,UCF-101和HMDB-51)的最先进的性能。
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Theoretical properties of bilevel problems are well studied when the lower-level problem is strongly convex. In this work, we focus on bilevel optimization problems without the strong-convexity assumption. In these cases, we first show that the common local optimality measures such as KKT condition or regularization can lead to undesired consequences. Then, we aim to identify the mildest conditions that make bilevel problems tractable. We identify two classes of growth conditions on the lower-level objective that leads to continuity. Under these assumptions, we show that the local optimality of the bilevel problem can be defined via the Goldstein stationarity condition of the hyper-objective. We then propose the Inexact Gradient-Free Method (IGFM) to solve the bilevel problem, using an approximate zeroth order oracle that is of independent interest. Our non-asymptotic analysis demonstrates that the proposed method can find a $(\delta, \varepsilon)$ Goldstein stationary point for bilevel problems with a zeroth order oracle complexity that is polynomial in $d, 1/\delta$ and $1/\varepsilon$.
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Optical coherence tomography (OCT) captures cross-sectional data and is used for the screening, monitoring, and treatment planning of retinal diseases. Technological developments to increase the speed of acquisition often results in systems with a narrower spectral bandwidth, and hence a lower axial resolution. Traditionally, image-processing-based techniques have been utilized to reconstruct subsampled OCT data and more recently, deep-learning-based methods have been explored. In this study, we simulate reduced axial scan (A-scan) resolution by Gaussian windowing in the spectral domain and investigate the use of a learning-based approach for image feature reconstruction. In anticipation of the reduced resolution that accompanies wide-field OCT systems, we build upon super-resolution techniques to explore methods to better aid clinicians in their decision-making to improve patient outcomes, by reconstructing lost features using a pixel-to-pixel approach with an altered super-resolution generative adversarial network (SRGAN) architecture.
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Stance detection refers to the task of extracting the standpoint (Favor, Against or Neither) towards a target in given texts. Such research gains increasing attention with the proliferation of social media contents. The conventional framework of handling stance detection is converting it into text classification tasks. Deep learning models have already replaced rule-based models and traditional machine learning models in solving such problems. Current deep neural networks are facing two main challenges which are insufficient labeled data and information in social media posts and the unexplainable nature of deep learning models. A new pre-trained language model chatGPT was launched on Nov 30, 2022. For the stance detection tasks, our experiments show that ChatGPT can achieve SOTA or similar performance for commonly used datasets including SemEval-2016 and P-Stance. At the same time, ChatGPT can provide explanation for its own prediction, which is beyond the capability of any existing model. The explanations for the cases it cannot provide classification results are especially useful. ChatGPT has the potential to be the best AI model for stance detection tasks in NLP, or at least change the research paradigm of this field. ChatGPT also opens up the possibility of building explanatory AI for stance detection.
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Image manipulation localization aims at distinguishing forged regions from the whole test image. Although many outstanding prior arts have been proposed for this task, there are still two issues that need to be further studied: 1) how to fuse diverse types of features with forgery clues; 2) how to progressively integrate multistage features for better localization performance. In this paper, we propose a tripartite progressive integration network (TriPINet) for end-to-end image manipulation localization. First, we extract both visual perception information, e.g., RGB input images, and visual imperceptible features, e.g., frequency and noise traces for forensic feature learning. Second, we develop a guided cross-modality dual-attention (gCMDA) module to fuse different types of forged clues. Third, we design a set of progressive integration squeeze-and-excitation (PI-SE) modules to improve localization performance by appropriately incorporating multiscale features in the decoder. Extensive experiments are conducted to compare our method with state-of-the-art image forensics approaches. The proposed TriPINet obtains competitive results on several benchmark datasets.
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Domain adaptation aims to transfer the knowledge acquired by models trained on (data-rich) source domains to (low-resource) target domains, for which a popular method is invariant representation learning. While they have been studied extensively for classification and regression problems, how they apply to ranking problems, where the data and metrics have a list structure, is not well understood. Theoretically, we establish a domain adaptation generalization bound for ranking under listwise metrics such as MRR and NDCG. The bound suggests an adaptation method via learning list-level domain-invariant feature representations, whose benefits are empirically demonstrated by unsupervised domain adaptation experiments on real-world ranking tasks, including passage reranking. A key message is that for domain adaptation, the representations should be analyzed at the same level at which the metric is computed, as we show that learning invariant representations at the list level is most effective for adaptation on ranking problems.
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