Generalized Labeled Multi-Bernoulli (GLMB) densities arise in a host of multi-object system applications analogous to Gaussians in single-object filtering. However, computing the GLMB filtering density requires solving NP-hard problems. To alleviate this computational bottleneck, we develop a linear complexity Gibbs sampling framework for GLMB density computation. Specifically, we propose a tempered Gibbs sampler that exploits the structure of the GLMB filtering density to achieve an $\mathcal{O}(T(P+M))$ complexity, where $T$ is the number of iterations of the algorithm, $P$ and $M$ are the number hypothesized objects and measurements. This innovation enables an $\mathcal{O}(T(P+M+\log(T))+PM)$ complexity implementation of the GLMB filter. Convergence of the proposed Gibbs sampler is established and numerical studies are presented to validate the proposed GLMB filter implementation.
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Graph neural networks (GNNs) have been shown to be highly sensitive to the choice of aggregation function. While summing over a node's neighbours can approximate any permutation-invariant function over discrete inputs, Cohen-Karlik et al. [2020] proved there are set-aggregation problems for which summing cannot generalise to unbounded inputs, proposing recurrent neural networks regularised towards permutation-invariance as a more expressive aggregator. We show that these results carry over to the graph domain: GNNs equipped with recurrent aggregators are competitive with state-of-the-art permutation-invariant aggregators, on both synthetic benchmarks and real-world problems. However, despite the benefits of recurrent aggregators, their $O(V)$ depth makes them both difficult to parallelise and harder to train on large graphs. Inspired by the observation that a well-behaved aggregator for a GNN is a commutative monoid over its latent space, we propose a framework for constructing learnable, commutative, associative binary operators. And with this, we construct an aggregator of $O(\log V)$ depth, yielding exponential improvements for both parallelism and dependency length while achieving performance competitive with recurrent aggregators. Based on our empirical observations, our proposed learnable commutative monoid (LCM) aggregator represents a favourable tradeoff between efficient and expressive aggregators.
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This paper introduces the use of evolutionary algorithms for solving differential equations. The solution is obtained by optimizing a deep neural network whose loss function is defined by the residual terms from the differential equations. Recent studies have used stochastic gradient descent (SGD) variants to train these physics-informed neural networks (PINNs), but these methods can struggle to find accurate solutions due to optimization challenges. When solving differential equations, it is important to find the globally optimum parameters of the network, rather than just finding a solution that works well during training. SGD only searches along a single gradient direction, so it may not be the best approach for training PINNs with their accompanying complex optimization landscapes. In contrast, evolutionary algorithms perform a parallel exploration of different solutions in order to avoid getting stuck in local optima and can potentially find more accurate solutions. However, evolutionary algorithms can be slow, which can make them difficult to use in practice. To address this, we provide a set of five benchmark problems with associated performance metrics and baseline results to support the development of evolutionary algorithms for enhanced PINN training. As a baseline, we evaluate the performance and speed of using the widely adopted Covariance Matrix Adaptation Evolution Strategy (CMA-ES) for solving PINNs. We provide the loss and training time for CMA-ES run on TensorFlow, and CMA-ES and SGD run on JAX (with GPU acceleration) for the five benchmark problems. Our results show that JAX-accelerated evolutionary algorithms, particularly CMA-ES, can be a useful approach for solving differential equations. We hope that our work will support the exploration and development of alternative optimization algorithms for the complex task of optimizing PINNs.
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Purpose: The aim of this study was to demonstrate the utility of unsupervised domain adaptation (UDA) in automated knee osteoarthritis (OA) phenotype classification using a small dataset (n=50). Materials and Methods: For this retrospective study, we collected 3,166 three-dimensional (3D) double-echo steady-state magnetic resonance (MR) images from the Osteoarthritis Initiative dataset and 50 3D turbo/fast spin-echo MR images from our institute (in 2020 and 2021) as the source and target datasets, respectively. For each patient, the degree of knee OA was initially graded according to the MRI Osteoarthritis Knee Score (MOAKS) before being converted to binary OA phenotype labels. The proposed UDA pipeline included (a) pre-processing, which involved automatic segmentation and region-of-interest cropping; (b) source classifier training, which involved pre-training phenotype classifiers on the source dataset; (c) target encoder adaptation, which involved unsupervised adaption of the source encoder to the target encoder and (d) target classifier validation, which involved statistical analysis of the target classification performance evaluated by the area under the receiver operating characteristic curve (AUROC), sensitivity, specificity and accuracy. Additionally, a classifier was trained without UDA for comparison. Results: The target classifier trained with UDA achieved improved AUROC, sensitivity, specificity and accuracy for both knee OA phenotypes compared with the classifier trained without UDA. Conclusion: The proposed UDA approach improves the performance of automated knee OA phenotype classification for small target datasets by utilising a large, high-quality source dataset for training. The results successfully demonstrated the advantages of the UDA approach in classification on small datasets.
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Principal Component Analysis (PCA) and its exponential family extensions have three components: observations, latents and parameters of a linear transformation. We consider a generalised setting where the canonical parameters of the exponential family are a nonlinear transformation of the latents. We show explicit relationships between particular neural network architectures and the corresponding statistical models. We find that deep equilibrium models -- a recently introduced class of implicit neural networks -- solve maximum a-posteriori (MAP) estimates for the latents and parameters of the transformation. Our analysis provides a systematic way to relate activation functions, dropout, and layer structure, to statistical assumptions about the observations, thus providing foundational principles for unsupervised DEQs. For hierarchical latents, individual neurons can be interpreted as nodes in a deep graphical model. Our DEQ feature maps are end-to-end differentiable, enabling fine-tuning for downstream tasks.
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National Health and Nutritional Status Survey (NHANSS) is conducted annually by the Ministry of Health in Negara Brunei Darussalam to assess the population health and nutritional patterns and characteristics. The main aim of this study was to discover meaningful patterns (groups) from the obese sample of NHANSS data by applying data reduction and interpretation techniques. The mixed nature of the variables (qualitative and quantitative) in the data set added novelty to the study. Accordingly, the Categorical Principal Component (CATPCA) technique was chosen to interpret the meaningful results. The relationships between obesity and the lifestyle factors like demography, socioeconomic status, physical activity, dietary behavior, history of blood pressure, diabetes, etc., were determined based on the principal components generated by CATPCA. The results were validated with the help of the split method technique to counter verify the authenticity of the generated groups. Based on the analysis and results, two subgroups were found in the data set, and the salient features of these subgroups have been reported. These results can be proposed for the betterment of the healthcare industry.
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Barlow Twins自制学习目标既不需要负样本或不对称的学习更新,从而与计算机视觉中当前最新艺术相提并论。因此,我们提出了音频Barlow双胞胎,这是一种新颖的自我监督音频表示方法,将Barlow Twins适应音频域。我们在大规模音频数据集音频集上预先培训,并评估来自2021年HEAR 2021挑战的18个任务的学习表现质量,从而取得了超越或以其他方式与当前最新的结果相同的结果。 - 例如,歧视自我监督的学习方法来表示音频表示学习。https://github.com/jonahanton/ssl_audio上的代码。
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联合学习(FL)是以分散的方式共同训练机器学习算法的范式。 FL中的大多数研究都集中在基于神经网络的方法上,但是,由于克服算法的迭代和添加性特征的挑战,在联合学习中基于XGBoost的方法(例如XGBOOST)在联合学习中没有得到反应。基于决策树的模型,尤其是XGBoost,可以处理非IID数据,这对于联合学习框架中使用的算法很重要,因为数据的基本特征是分散的,并且具有本质上非IID的风险。在本文中,我们专注于研究通过对各种基于样本量的数据偏斜方案进行实验以及这些模型在各种非IID方案下的性能,通过非IID分布的影响如何受到非IID分布的影响。我们在多个不同的数据集中进行了一组广泛的实验,并进行了不同的数据偏斜分区。我们的实验结果表明,尽管有各种分区比率,但模型的性能保持一致,并且与以集中式方式训练的模型接近或同样良好。
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目的:大大缩短定量3D化学交换饱和转移(CEST)和半固体磁化转移(MT)成像所需的采集时间,并允许快速化学交换参数图重建。方法:三维CEST和MT磁共振指纹(MRF)数据集的L-精氨酸幻象,全脑,全脑和小腿肌肉的健康志愿者,癌症患者和心脏病患者是使用3T临床扫描仪在3T不同的位点使用3T临床扫描仪获得的3种不同的扫描仪模型和线圈。然后,设计和训练了一个生成的对抗网络监督框架(GAN-CEST),以学习从减少的输入数据空间到定量交换参数空间的映射,同时保留感知和定量内容。结果:GAN-CEST 3D采集时间为42-52秒,比CEST-MRF短70%。整个大脑的定量重建需要0.8秒。在地面真相和基于GAN的L-精氨酸浓度和pH值之间观察到了极好的一致性(Pearson的R> 0.97,NRMSE <1.5%)。来自脑肿瘤受试者的gan-cest图像产生的半固体量分数和汇率NRMSE为3.8 $ \ pm $ 1.3%和4.6 $ \ pm $ 1.3%,SSIM和96.3 $ \ pm $ \ pm $ 1.6%和95.0 $ \ pm $ 2.4%。半固体交换参数的NRMSE <7%和SSIM> 94%的小腿肌肉交换参数的映射。与MRF相比,在具有较大敏感性伪像的区域中,Gan-Cest表现出改善的性能和噪声降低。结论:Gan-Cest可以大大减少定量半固体MT/CEST映射的获取时间,同时即使在训练过程中无法使用的病理和扫描仪模型时,也可以保持性能。
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我们提出了一系列两项研究,以了解基于语音的人机相互作用期间用户的情感状态。重点放在通信错误或失败的情况下。特别是,我们有兴趣了解与其他情感状态有关的“混乱”。研究由两种类型的任务组成:(1)与基于语音的虚拟代理的通信有关:与机器交谈并了解机器所说的话,(2)与参与者解决的无通信,解决问题的任务难题和谜语,但被要求口头解释机器的答案。我们收集了参与者情感状态的视听数据和自我报告。我们报告了两项研究的结果和分析收集的数据。根据注释者的观察对第一项研究进行了分析,并根据自我报告分析了第二项研究。
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