最近,蒙面图像建模(MIM)由于其能力从大量未标记的数据中学习而引起了人们的关注,并且已被证明对涉及自然图像的各种视觉任务有效。同时,由于未标记的图像的数量高,预计3D医学图像中的自我监督学习的潜力预计将是巨大的,以及质量标签的费用和困难。但是,MIM对医学图像的适用性仍然不确定。在本文中,我们证明了掩盖的图像建模方法还可以推进3D医学图像分析,除了自然图像。我们研究掩盖图像建模策略如何从3D医学图像分割的角度利用性能作为代表性的下游任务:i)与天真的对比度学习相比,蒙版的图像建模方法可以加快监督培训的收敛性,甚至更快(1.40美元$ \ times $ \ times $ $ $ )并最终产生更高的骰子分数; ii)预测具有较高掩盖比和相对较小的贴片大小的原始体素值是用于医学图像建模的非平凡的自我监督借口任务; iii)重建的轻质解码器或投影头设计对于3D医学图像上的掩盖图像建模非常有力,该图像加快了训练并降低成本; iv)最后,我们还研究了在不同的实际情况下使用不同图像分辨率和标记的数据比率的MIM方法的有效性。
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In optimization-based approaches to inverse problems and to statistical estimation, it is common to augment the objective with a regularizer to address challenges associated with ill-posedness. The choice of a suitable regularizer is typically driven by prior domain information and computational considerations. Convex regularizers are attractive as they are endowed with certificates of optimality as well as the toolkit of convex analysis, but exhibit a computational scaling that makes them ill-suited beyond moderate-sized problem instances. On the other hand, nonconvex regularizers can often be deployed at scale, but do not enjoy the certification properties associated with convex regularizers. In this paper, we seek a systematic understanding of the power and the limitations of convex regularization by investigating the following questions: Given a distribution, what are the optimal regularizers, both convex and nonconvex, for data drawn from the distribution? What properties of a data source govern whether it is amenable to convex regularization? We address these questions for the class of continuous and positively homogenous regularizers for which convex and nonconvex regularizers correspond, respectively, to convex bodies and star bodies. By leveraging dual Brunn-Minkowski theory, we show that a radial function derived from a data distribution is the key quantity for identifying optimal regularizers and for assessing the amenability of a data source to convex regularization. Using tools such as $\Gamma$-convergence, we show that our results are robust in the sense that the optimal regularizers for a sample drawn from a distribution converge to their population counterparts as the sample size grows large. Finally, we give generalization guarantees that recover previous results for polyhedral regularizers (i.e., dictionary learning) and lead to new ones for semidefinite regularizers.
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In this work, we give efficient algorithms for privately estimating a Gaussian distribution in both pure and approximate differential privacy (DP) models with optimal dependence on the dimension in the sample complexity. In the pure DP setting, we give an efficient algorithm that estimates an unknown $d$-dimensional Gaussian distribution up to an arbitrary tiny total variation error using $\widetilde{O}(d^2 \log \kappa)$ samples while tolerating a constant fraction of adversarial outliers. Here, $\kappa$ is the condition number of the target covariance matrix. The sample bound matches best non-private estimators in the dependence on the dimension (up to a polylogarithmic factor). We prove a new lower bound on differentially private covariance estimation to show that the dependence on the condition number $\kappa$ in the above sample bound is also tight. Prior to our work, only identifiability results (yielding inefficient super-polynomial time algorithms) were known for the problem. In the approximate DP setting, we give an efficient algorithm to estimate an unknown Gaussian distribution up to an arbitrarily tiny total variation error using $\widetilde{O}(d^2)$ samples while tolerating a constant fraction of adversarial outliers. Prior to our work, all efficient approximate DP algorithms incurred a super-quadratic sample cost or were not outlier-robust. For the special case of mean estimation, our algorithm achieves the optimal sample complexity of $\widetilde O(d)$, improving on a $\widetilde O(d^{1.5})$ bound from prior work. Our pure DP algorithm relies on a recursive private preconditioning subroutine that utilizes the recent work on private mean estimation [Hopkins et al., 2022]. Our approximate DP algorithms are based on a substantial upgrade of the method of stabilizing convex relaxations introduced in [Kothari et al., 2022].
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Prototyping and validating hardware-software components, sub-systems and systems within the intelligent transportation system-of-systems framework requires a modular yet flexible and open-access ecosystem. This work presents our attempt towards developing such a comprehensive research and education ecosystem, called AutoDRIVE, for synergistically prototyping, simulating and deploying cyber-physical solutions pertaining to autonomous driving as well as smart city management. AutoDRIVE features both software as well as hardware-in-the-loop testing interfaces with openly accessible scaled vehicle and infrastructure components. The ecosystem is compatible with a variety of development frameworks, and supports both single and multi-agent paradigms through local as well as distributed computing. Most critically, AutoDRIVE is intended to be modularly expandable to explore emergent technologies, and this work highlights various complementary features and capabilities of the proposed ecosystem by demonstrating four such deployment use-cases: (i) autonomous parking using probabilistic robotics approach for mapping, localization, path planning and control; (ii) behavioral cloning using computer vision and deep imitation learning; (iii) intersection traversal using vehicle-to-vehicle communication and deep reinforcement learning; and (iv) smart city management using vehicle-to-infrastructure communication and internet-of-things.
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Neural networks have revolutionized the area of artificial intelligence and introduced transformative applications to almost every scientific field and industry. However, this success comes at a great price; the energy requirements for training advanced models are unsustainable. One promising way to address this pressing issue is by developing low-energy neuromorphic hardware that directly supports the algorithm's requirements. The intrinsic non-volatility, non-linearity, and memory of spintronic devices make them appealing candidates for neuromorphic devices. Here we focus on the reservoir computing paradigm, a recurrent network with a simple training algorithm suitable for computation with spintronic devices since they can provide the properties of non-linearity and memory. We review technologies and methods for developing neuromorphic spintronic devices and conclude with critical open issues to address before such devices become widely used.
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水下成像是海洋机器人执行的一项关键任务,用于广泛的应用,包括水产养殖,海洋基础设施检查和环境监测。但是,水柱的影响(例如衰减和反向散射)会大大改变捕获的水下图像的颜色和质量。由于水条件的变化和这些影响的范围依赖性,恢复水下图像是一个具有挑战性的问题。这会影响下游感知任务,包括深度估计和3D重建。在本文中,我们推进了神经辐射场(NERFS)的最先进,以实现物理信息密集的深度估计和颜色校正。我们提出的方法Waternerf估计了水下图像形成的基于物理的模型的参数,从而导致混合数据驱动和基于模型的解决方案。在确定了场景结构和辐射场之后,我们可以产生降级和校正的水下图像的新颖观点,以及场景的密集深度。我们对实际水下数据集进行定性和定量评估所提出的方法。
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尽管机器人学课程在高等教育方面已建立,但这些课程通常专注于理论,有时缺乏对开发,部署和将软件应用于真实硬件的技术的系统覆盖。此外,大多数用于机器人教学的硬件平台是针对中学水平的年轻学生的低级玩具。为了解决这一差距,开发了一个自动驾驶汽车硬件平台,称为第1 f1 f1tth,用于教授自动驾驶系统。本文介绍了以“赛车”和替换考试的竞赛为主题的各种教育水平教学模块和软件堆栈。第1辆车提供了一个模块化硬件平台及其相关软件,用于教授自动驾驶算法的基础知识。从基本的反应方法到高级计划算法,教学模块通过使用第1辆车的自动驾驶来增强学生的计算思维。第1辆汽车填补了研究平台和低端玩具车之间的空白,并提供了学习自主系统中主题的动手经验。多年的四所大学为他们的学期本科和研究生课程采用了教学模块。学生反馈用于分析第1个平台的有效性。超过80%的学生强烈同意,硬件平台和模块大大激发了他们的学习,而超过70%的学生强烈同意,硬件增强了他们对学科的理解。调查结果表明,超过80%的学生强烈同意竞争激励他们参加课程。
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与标准动态范围(SDR)视频相比,高动态范围(HDR)视频可以代表更大的亮度和色彩范围,并且正迅速成为行业标准。与传统SDR视频相比,HDR视频具有更具挑战性的捕获,传输和显示要求。凭借其更大的深度,高级的电流传输功能以及更广泛的颜色范围,因此需要专门设计用于预测HDR视频质量的视频质量算法。为此,我们介绍了HDR视频的首次公开发布的大规模主观研究。我们研究扭曲的影响,例如压缩和混叠对HDR视频质量的影响。我们还通过在黑暗实验室环境和更明亮的客厅环境中进行研究来研究环境照明对HDR视频感知质量的影响。总共有66名受试者参加了这项研究,并收集了20,000多个意见分数,这使得这成为有史以来最大的HDR视频质量研究。我们预计,该数据集将成为研究人员为HDR视频开发更好的感知质量模型的宝贵资源。
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在电缆驱动的平行机器人(CDPR)中,单个电缆故障通常会导致整个机器人的完全故障。但是,通常可以通过重新配置框架上的电缆附件来恢复丢失的静态工作空间(由于故障)。通过将运动冗余以在实时冗余分辨率控制器中操纵的移动线性滑块的形式添加到机器人中,从而引入了此功能。提出的工作将该控制器与在线故障检测框架相结合,以开发自动任务恢复的完整失误耐受控制方案。该解决方案通过将最终效应器的姿势估计与仅依靠最终效应器信息的交互式多重模型(IMM)算法相结合,从而提供了鲁棒性。然后将故障和姿势估计方案绑定到冗余分辨率方法中,以产生无缝的自动任务(轨迹)恢复方法,以实现电缆故障。
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给定尺寸$ d $中的独立标准高斯点$ v_1,\ ldots,v_n $,对于$(n,d)$的值(n,d)$的值很高,概率很高,同时通过所有要点?将椭圆形拟合到随机点的基本问题与低级别矩阵分解,独立的组件分析和主成分分析有连接。基于有力的数值证据,桑德森,帕里洛和威尔斯基[Proc。关于决策和控制会议,第6031-6036页,2013年]猜想,椭圆形拟合问题的问题从可行的到不可行的$ n $增加,并在$ n \ sim d^2/4处急剧阈值$。我们通过为某些$ n = \ omega(\,d^2/\ log^5(d)\,)$构建合适的椭圆形来解决这个猜想,从而改善了Ghosh等人的先前工作。 [Proc。关于计算机科学基础的研讨会,第954-965、2020页],需要$ n = o(d^{3/2})$。我们的证明证明了Saunderson等人的最小二乘结构的可行性。使用对特定非标准随机矩阵的特征向量和特征值进行仔细的分析。
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