We present a novel method to provide efficient and highly detailed reconstructions. Inspired by wavelets, our main idea is to learn a neural field that decompose the signal both spatially and frequency-wise. We follow the recent grid-based paradigm for spatial decomposition, but unlike existing work, encourage specific frequencies to be stored in each grid via Fourier features encodings. We then apply a multi-layer perceptron with sine activations, taking these Fourier encoded features in at appropriate layers so that higher-frequency components are accumulated on top of lower-frequency components sequentially, which we sum up to form the final output. We demonstrate that our method outperforms the state of the art regarding model compactness and efficiency on multiple tasks: 2D image fitting, 3D shape reconstruction, and neural radiance fields.

Diffusion Probabilistic Models (DPMs) have shown a powerful capacity of generating high-quality image samples. Recently, diffusion autoencoders (Diff-AE) have been proposed to explore DPMs for representation learning via autoencoding. Their key idea is to jointly train an encoder for discovering meaningful representations from images and a conditional DPM as the decoder for reconstructing images. Considering that training DPMs from scratch will take a long time and there have existed numerous pre-trained DPMs, we propose \textbf{P}re-trained \textbf{D}PM \textbf{A}uto\textbf{E}ncoding (\textbf{PDAE}), a general method to adapt existing pre-trained DPMs to the decoders for image reconstruction, with better training efficiency and performance than Diff-AE. Specifically, we find that the reason that pre-trained DPMs fail to reconstruct an image from its latent variables is due to the information loss of forward process, which causes a gap between their predicted posterior mean and the true one. From this perspective, the classifier-guided sampling method can be explained as computing an extra mean shift to fill the gap, reconstructing the lost class information in samples. These imply that the gap corresponds to the lost information of the image, and we can reconstruct the image by filling the gap. Drawing inspiration from this, we employ a trainable model to predict a mean shift according to encoded representation and train it to fill as much gap as possible, in this way, the encoder is forced to learn as much information as possible from images to help the filling. By reusing a part of network of pre-trained DPMs and redesigning the weighting scheme of diffusion loss, PDAE can learn meaningful representations from images efficiently. Extensive experiments demonstrate the effectiveness, efficiency and flexibility of PDAE.

Deep learning (DL) has become a driving force and has been widely adopted in many domains and applications with competitive performance. In practice, to solve the nontrivial and complicated tasks in real-world applications, DL is often not used standalone, but instead contributes as a piece of gadget of a larger complex AI system. Although there comes a fast increasing trend to study the quality issues of deep neural networks (DNNs) at the model level, few studies have been performed to investigate the quality of DNNs at both the unit level and the potential impacts on the system level. More importantly, it also lacks systematic investigation on how to perform the risk assessment for AI systems from unit level to system level. To bridge this gap, this paper initiates an early exploratory study of AI system risk assessment from both the data distribution and uncertainty angles to address these issues. We propose a general framework with an exploratory study for analyzing AI systems. After large-scale (700+ experimental configurations and 5000+ GPU hours) experiments and in-depth investigations, we reached a few key interesting findings that highlight the practical need and opportunities for more in-depth investigations into AI systems.

The deep learning community has witnessed an exponentially growing interest in self-supervised learning (SSL). However, it still remains unexplored how to build a framework for learning useful representations of raw music waveforms in a self-supervised manner. In this work, we design Music2Vec, a framework exploring different SSL algorithmic components and tricks for music audio recordings. Our model achieves comparable results to the state-of-the-art (SOTA) music SSL model Jukebox, despite being significantly smaller with less than 2% of parameters of the latter. The model will be released on Huggingface(Please refer to: https://huggingface.co/m-a-p/music2vec-v1)

Recent years have witnessed an astonishing explosion in the evolution of mobile applications powered by AI technologies. The rapid growth of AI frameworks enables the transition of AI technologies to mobile devices, significantly prompting the adoption of AI apps (i.e., apps that integrate AI into their functions) among smartphone devices. In this paper, we conduct the most extensive empirical study on 56,682 published AI apps from three perspectives: dataset characteristics, development issues, and user feedback and privacy. To this end, we build an automated AI app identification tool, AI Discriminator, that detects eligible AI apps from 7,259,232 mobile apps. First, we carry out a dataset analysis, where we explore the AndroZoo large repository to identify AI apps and their core characteristics. Subsequently, we pinpoint key issues in AI app development (e.g., model protection). Finally, we focus on user reviews and user privacy protection. Our paper provides several notable findings. Some essential ones involve revealing the issue of insufficient model protection by presenting the lack of model encryption, and demonstrating the risk of user privacy data being leaked. We published our large-scale AI app datasets to inspire more future research.

The Modboat is a low-cost, underactuated, modular robot capable of surface swimming, docking to other modules, and undocking from them using only a single motor and two passive flippers. Undocking is achieved by causing intentional self-collision between the tails of neighboring modules in certain configurations; this becomes a challenge, however, when collective swimming as one connected component is desirable. Prior work has developed controllers that turn arbitrary configurations of docked Modboats into steerable vehicles, but they cannot counteract lateral forces and disturbances. In this work we present a centralized control strategy to create holonomic vehicles out of arbitrary configurations of docked Modboats using an iterative potential-field based search. We experimentally demonstrate that our controller performs well and can control surge and sway velocities and yaw angle simultaneously.

In this paper, we propose a novel multi-modal multi-task encoder-decoder pre-training framework (MMSpeech) for Mandarin automatic speech recognition (ASR), which employs both unlabeled speech and text data. The main difficulty in speech-text joint pre-training comes from the significant difference between speech and text modalities, especially for Mandarin speech and text. Unlike English and other languages with an alphabetic writing system, Mandarin uses an ideographic writing system where character and sound are not tightly mapped to one another. Therefore, we propose to introduce the phoneme modality into pre-training, which can help capture modality-invariant information between Mandarin speech and text. Specifically, we employ a multi-task learning framework including five self-supervised and supervised tasks with speech and text data. For end-to-end pre-training, we introduce self-supervised speech-to-pseudo-codes (S2C) and phoneme-to-text (P2T) tasks utilizing unlabeled speech and text data, where speech-pseudo-codes pairs and phoneme-text pairs are a supplement to the supervised speech-text pairs. To train the encoder to learn better speech representation, we introduce self-supervised masked speech prediction (MSP) and supervised phoneme prediction (PP) tasks to learn to map speech into phonemes. Besides, we directly add the downstream supervised speech-to-text (S2T) task into the pre-training process, which can further improve the pre-training performance and achieve better recognition results even without fine-tuning. Experiments on AISHELL-1 show that our proposed method achieves state-of-the-art performance, with a more than 40% relative improvement compared with other pre-training methods.

对于单眼360图像，深度估计是一个具有挑战性的，因为失真沿纬度增加。为了感知失真，现有方法致力于设计深层且复杂的网络体系结构。在本文中，我们提供了一种新的观点，该视角为360图像构建了可解释且稀疏的表示形式。考虑到几何结构在深度估计中的重要性，我们利用Contourlet变换来捕获光谱域中的显式几何提示，并将其与空间域中的隐含提示集成在一起。具体而言，我们提出了一个由卷积神经网络和Contourlet变换分支组成的神经轮廓网络。在编码器阶段，我们设计了一个空间光谱融合模块，以有效融合两种类型的提示。与编码器相反，我们采用了逆向方形变换，并通过学习的低通子带和带通道的定向子带来构成解码器中的深度。在三个流行的全景图像数据集上进行的实验表明，所提出的方法的表现优于最先进的方案，其收敛速度更快。代码可在https://github.com/zhijieshen-bjtu/neural-contourlet-network-for-mode上找到。

最近，基于水平表示的全景语义分割方法优于基于投影的解决方案，因为可以通过在垂直方向上压缩球形数据来有效地消除畸变。但是，这些方法忽略了之前的失真分布，并且仅限于不平衡的接收场，例如，接收场在垂直方向上足够，并且在水平方向上不足。不同的是，沿另一个方向压缩的垂直表示可以提供隐式失真先验，并扩大水平接收场。在本文中，我们结合了两种不同的表示，并从互补的角度提出了一种新颖的360 {\ deg}语义分割解决方案。我们的网络包括三个模块：特征提取模块，一个双向压缩模块和一个集合解码模块。首先，我们从Panorama提取多尺度功能。然后，设计一个双向压缩模块，将特征压缩为两个互补的低维表示，这些表示提供了内容感知和失真。此外，为了促进双向特征的融合，我们在合奏解码模块中设计了独特的自我蒸馏策略，以增强不同特征的相互作用并进一步提高性能。实验结果表明，我们的方法的表现优于最先进的解决方案，在定量评估上至少提高了10 \％的改进，同时显示出视觉外观上最佳性能。

无监督的域适应性（UDA）仅使用未标记的数据适应一个在一个域上训练的模型。已经进行了许多研究，特别是由于其高注释成本而用于语义分割。现有研究坚持这样的基本假设，即新领域没有标记的样品。但是，这个假设有几个问题。首先，考虑到ML的标准实践，可以在部署前确认该模型的性能，这是非常不现实的。确认需要标记的数据。其次，任何UDA方法都将具有一些超参数，需要一定数量的标记数据。为了纠正现实的错误对准，我们从以数据为中心的角度重新考虑UDA。具体而言，我们从假设我们确实可以访问最低标记数据级别的假设。然后，我们询问需要多少个标记样品来找到现有UDA方法令人满意的超参数。如果我们使用相同的数据来训练模型，例如填充，它的工作原理如何？我们进行实验，以流行的情况为{GTA5，Synthia} $ \ rightarrow $ CityScapes。我们的发现如下：i）对于某些UDA方法，只有几个标记的样品（即图像），例如五个，可以找到良好的超参数，例如五个，但这不适用于其他样品，ii）较高的芬特（ii）均超过了大多数的芬特。现有的UDA方法只有十个标记的图像。