无人驾驶飞行器(无人机)承诺成为下一代通信的内在部分,因为它们可以部署为提供无线连接到地面用户,以补充现有的地面网络。大多数现有研究使用UAV接入点的蜂窝覆盖率考虑了旋转翼UAV设计(即Quadcopters)。但是,我们预计固定翼的无人机在需要长途飞行时间(例如农村覆盖范围)的情况下更适合连接目的(例如农村覆盖率),因为与旋翼设计。由于固定翼无人机通常无法悬停在适当位置,因此它们的部署优化涉及以允许它们以节能的方式向地面用户提供高质量服务的方式优化其单独的飞行轨迹。在本文中,我们提出了一种多功能深度加强学习方法来优化固定翼UAV蜂窝接入点的能效,同时允许它们向地面用户提供高质量的服务。在我们的分散方法中,每个UAV都配备了Dueling Deep Q-Network(DDQN)代理,可以通过一系列时间步来调整UV的3D轨迹。通过与邻居协调,无人机以优化总系统能效的方式调整各个飞行轨迹。我们基准对我们对一系列启发式轨迹规划策略的方法进行基准,并证明我们的方法可以将系统能效提高到70%。
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可以部署作为空中基站(UAV-BS)的无人机飞行器,以便在增加网络需求,现有基础设施中的失败点或灾难的情况下为地面设备提供无线连接。然而,考虑到它们的板载电池容量有限,挑战无人机的能量是挑战。先前已经用于提高诸如多个无人机的能量利用的加强学习(RL)方法,然而,假设中央云控制器具有完全了解端设备的位置,即控制器周期性地扫描并发送更新无人机决策。在具有服务接地设备的UAVS的动态网络环境中,此假设在动态网络环境中是不切实际的。为了解决这个问题,我们提出了一种分散的Q学习方法,其中每个UAV-BS都配备了一种自主代理,可以最大化移动地设备的连接,同时提高其能量利用率。实验结果表明,该设计的设计显着优于联合最大化连接地面装置的数量和UAV-BS的能量利用中的集中方法。
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提供可靠的连接到蜂窝连接的无人机可以非常具有挑战性;它们的性能高度取决于周围环境的性质,例如地面BSS的密度和高度。另一方面,高层建筑可能阻断来自地面BS的不期望的干扰信号,从而提高了UVS与其服务BS之间的连接。为了解决此类环境中的无人机的连接,本文提出了一种RL算法,以动态优化UAV的高度,因为它在通过环境中移动,目标是提高其经历的吞吐量。所提出的解决方案是使用来自爱尔兰都柏林市中心的两个不同地点的实验获得的测量来评估。在第一场景中,UAV连接到宏小区,而在第二场景中,UAV将在双层移动网络中关联到不同的小单元。结果表明,与基线方法相比,该溶液的吞吐量增加了6%至41%。
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This article concerns Bayesian inference using deep linear networks with output dimension one. In the interpolating (zero noise) regime we show that with Gaussian weight priors and MSE negative log-likelihood loss both the predictive posterior and the Bayesian model evidence can be written in closed form in terms of a class of meromorphic special functions called Meijer-G functions. These results are non-asymptotic and hold for any training dataset, network depth, and hidden layer widths, giving exact solutions to Bayesian interpolation using a deep Gaussian process with a Euclidean covariance at each layer. Through novel asymptotic expansions of Meijer-G functions, a rich new picture of the role of depth emerges. Specifically, we find that the posteriors in deep linear networks with data-independent priors are the same as in shallow networks with evidence maximizing data-dependent priors. In this sense, deep linear networks make provably optimal predictions. We also prove that, starting from data-agnostic priors, Bayesian model evidence in wide networks is only maximized at infinite depth. This gives a principled reason to prefer deeper networks (at least in the linear case). Finally, our results show that with data-agnostic priors a novel notion of effective depth given by \[\#\text{hidden layers}\times\frac{\#\text{training data}}{\text{network width}}\] determines the Bayesian posterior in wide linear networks, giving rigorous new scaling laws for generalization error.
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Vision-based tactile sensors have gained extensive attention in the robotics community. The sensors are highly expected to be capable of extracting contact information i.e. haptic information during in-hand manipulation. This nature of tactile sensors makes them a perfect match for haptic feedback applications. In this paper, we propose a contact force estimation method using the vision-based tactile sensor DIGIT, and apply it to a position-force teleoperation architecture for force feedback. The force estimation is done by building a depth map for DIGIT gel surface deformation measurement and applying a regression algorithm on estimated depth data and ground truth force data to get the depth-force relationship. The experiment is performed by constructing a grasping force feedback system with a haptic device as a leader robot and a parallel robot gripper as a follower robot, where the DIGIT sensor is attached to the tip of the robot gripper to estimate the contact force. The preliminary results show the capability of using the low-cost vision-based sensor for force feedback applications.
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Deploying machine learning models in production may allow adversaries to infer sensitive information about training data. There is a vast literature analyzing different types of inference risks, ranging from membership inference to reconstruction attacks. Inspired by the success of games (i.e., probabilistic experiments) to study security properties in cryptography, some authors describe privacy inference risks in machine learning using a similar game-based style. However, adversary capabilities and goals are often stated in subtly different ways from one presentation to the other, which makes it hard to relate and compose results. In this paper, we present a game-based framework to systematize the body of knowledge on privacy inference risks in machine learning.
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This paper presents a class of new fast non-trainable entropy-based confidence estimation methods for automatic speech recognition. We show how per-frame entropy values can be normalized and aggregated to obtain a confidence measure per unit and per word for Connectionist Temporal Classification (CTC) and Recurrent Neural Network Transducer (RNN-T) models. Proposed methods have similar computational complexity to the traditional method based on the maximum per-frame probability, but they are more adjustable, have a wider effective threshold range, and better push apart the confidence distributions of correct and incorrect words. We evaluate the proposed confidence measures on LibriSpeech test sets, and show that they are up to 2 and 4 times better than confidence estimation based on the maximum per-frame probability at detecting incorrect words for Conformer-CTC and Conformer-RNN-T models, respectively.
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Training a neural network requires choosing a suitable learning rate, involving a trade-off between speed and effectiveness of convergence. While there has been considerable theoretical and empirical analysis of how large the learning rate can be, most prior work focuses only on late-stage training. In this work, we introduce the maximal initial learning rate $\eta^{\ast}$ - the largest learning rate at which a randomly initialized neural network can successfully begin training and achieve (at least) a given threshold accuracy. Using a simple approach to estimate $\eta^{\ast}$, we observe that in constant-width fully-connected ReLU networks, $\eta^{\ast}$ demonstrates different behavior to the maximum learning rate later in training. Specifically, we find that $\eta^{\ast}$ is well predicted as a power of $(\text{depth} \times \text{width})$, provided that (i) the width of the network is sufficiently large compared to the depth, and (ii) the input layer of the network is trained at a relatively small learning rate. We further analyze the relationship between $\eta^{\ast}$ and the sharpness $\lambda_{1}$ of the network at initialization, indicating that they are closely though not inversely related. We formally prove bounds for $\lambda_{1}$ in terms of $(\text{depth} \times \text{width})$ that align with our empirical results.
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Deep Learning (DL) models tend to perform poorly when the data comes from a distribution different from the training one. In critical applications such as medical imaging, out-of-distribution (OOD) detection helps to identify such data samples, increasing the model's reliability. Recent works have developed DL-based OOD detection that achieves promising results on 2D medical images. However, scaling most of these approaches on 3D images is computationally intractable. Furthermore, the current 3D solutions struggle to achieve acceptable results in detecting even synthetic OOD samples. Such limited performance might indicate that DL often inefficiently embeds large volumetric images. We argue that using the intensity histogram of the original CT or MRI scan as embedding is descriptive enough to run OOD detection. Therefore, we propose a histogram-based method that requires no DL and achieves almost perfect results in this domain. Our proposal is supported two-fold. We evaluate the performance on the publicly available datasets, where our method scores 1.0 AUROC in most setups. And we score second in the Medical Out-of-Distribution challenge without fine-tuning and exploiting task-specific knowledge. Carefully discussing the limitations, we conclude that our method solves the sample-level OOD detection on 3D medical images in the current setting.
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Autonomous vehicle (AV) stacks are typically built in a modular fashion, with explicit components performing detection, tracking, prediction, planning, control, etc. While modularity improves reusability, interpretability, and generalizability, it also suffers from compounding errors, information bottlenecks, and integration challenges. To overcome these challenges, a prominent approach is to convert the AV stack into an end-to-end neural network and train it with data. While such approaches have achieved impressive results, they typically lack interpretability and reusability, and they eschew principled analytical components, such as planning and control, in favor of deep neural networks. To enable the joint optimization of AV stacks while retaining modularity, we present DiffStack, a differentiable and modular stack for prediction, planning, and control. Crucially, our model-based planning and control algorithms leverage recent advancements in differentiable optimization to produce gradients, enabling optimization of upstream components, such as prediction, via backpropagation through planning and control. Our results on the nuScenes dataset indicate that end-to-end training with DiffStack yields substantial improvements in open-loop and closed-loop planning metrics by, e.g., learning to make fewer prediction errors that would affect planning. Beyond these immediate benefits, DiffStack opens up new opportunities for fully data-driven yet modular and interpretable AV architectures. Project website: https://sites.google.com/view/diffstack
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