机器学习(ML)算法在帮助不同学科和机构的科学社区解决大型和多样化的数据问题方面表现出了增长的趋势。但是,许多可用的ML工具在编程方面要求且计算成本高昂。 MlexChange项目旨在建立一个配备有能力工具的协作平台,该平台使科学家和设施使用者没有深刻的ML背景来使用ML和计算资源进行科学发现。在高水平上,我们针对完整的用户体验,在该体验中,可以通过Web应用程序可以轻松获得管理和交换ML算法,工作流和数据。到目前为止,我们已经构建了四个主要组件,即中央职位管理器,集中式内容注册表,用户门户和搜索引擎,并成功地将这些组件部署到了测试服务器上。由于每个组件都是一个独立的容器,因此可以轻松地在不同尺度的服务器上部署整个平台或其个人服务,从笔记本电脑(通常是单个用户)到高性能群集(HPC)(同时)通过许多用户。因此,MlexChange使用方案使灵活性变得灵活 - 用户可以从远程服务器访问服务和资源,也可以在其本地网络中运行整个平台或其个人服务。
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无监督和半监督的ML方法,例如变异自动编码器(VAE),由于其在分离的表述方面的能力以及找到具有复杂实验数据的潜在分类和回归的能力,因此在多个物理,化学和材料科学方面已广泛采用。 。像其他ML问题一样,VAE需要高参数调整,例如,平衡Kullback Leibler(KL)和重建项。但是,训练过程以及由此产生的歧管拓扑和连通性不仅取决于超参数,还取决于训练过程中的演变。由于在高维超参数空间中详尽搜索的效率低下,因此我们在这里探索了一种潜在的贝叶斯优化方法(ZBO)方法,用于用于无监督和半监测的ML的超参数轨迹优化,并证明了连接的ML,并证明VAE具有旋转不变。我们证明了这种方法的应用,用于寻找血浆纳米颗粒材料系统的MNIST和实验数据的联合离散和连续旋转不变表示。已广泛讨论了所提出的方法的性能,它允许对其他ML模型进行任何高维超参数调整或轨迹优化。
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机器学习方法的最新进展以及扫描探针显微镜(SPMS)的可编程接口的新兴可用性使自动化和自动显微镜在科学界的关注方面推向了最前沿。但是,启用自动显微镜需要开发特定于任务的机器学习方法,了解物理发现与机器学习之间的相互作用以及完全定义的发现工作流程。反过来,这需要平衡领域科学家的身体直觉和先验知识与定义实验目标和机器学习算法的奖励,这些算法可以将它们转化为特定的实验协议。在这里,我们讨论了贝叶斯活跃学习的基本原理,并说明了其对SPM的应用。我们从高斯过程作为一种简单的数据驱动方法和对物理模型的贝叶斯推断作为基于物理功能的扩展的贝叶斯推断,再到更复杂的深内核学习方法,结构化的高斯过程和假设学习。这些框架允许使用先验数据,在光谱数据中编码的特定功能以及在实验过程中表现出的物理定律的探索。讨论的框架可以普遍应用于结合成像和光谱,SPM方法,纳米识别,电子显微镜和光谱法以及化学成像方法的所有技术,并且对破坏性或不可逆测量的影响特别影响。
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优化在离散变量上的高度复杂的成本/能源功能是不同科学学科和行业的许多公开问题的核心。一个主要障碍是在硬实例中的某些变量子集之间的出现,导致临界减慢或集体冻结了已知的随机本地搜索策略。通常需要指数计算工作来解冻这种变量,并探索配置空间的其他看不见的区域。在这里,我们通过开发自适应梯度的策略来介绍一个量子启发的非本球非识别蒙特卡罗(NMC)算法,可以有效地学习成本函数的关键实例的几何特征。该信息随行使用,以构造空间不均匀的热波动,用于以各种长度尺度集体未填充变量,规避昂贵的勘探与开发权衡。我们将算法应用于两个最具挑战性的组合优化问题:随机k可满足(K-SAT)附近计算阶段转换和二次分配问题(QAP)。我们在专业的确定性求解器和通用随机求解器上观察到显着的加速和鲁棒性。特别是,对于90%的随机4-SAT实例,我们发现了最佳专用确定性算法无法访问的解决方案,该算法(SP)具有最强的10%实例的解决方案质量的大小提高。我们还通过最先进的通用随机求解器(APT)显示出在最先进的通用随机求解器(APT)上的时间到溶液的两个数量级改善。
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In this paper we explore the task of modeling (semi) structured object sequences; in particular we focus our attention on the problem of developing a structure-aware input representation for such sequences. In such sequences, we assume that each structured object is represented by a set of key-value pairs which encode the attributes of the structured object. Given a universe of keys, a sequence of structured objects can then be viewed as an evolution of the values for each key, over time. We encode and construct a sequential representation using the values for a particular key (Temporal Value Modeling - TVM) and then self-attend over the set of key-conditioned value sequences to a create a representation of the structured object sequence (Key Aggregation - KA). We pre-train and fine-tune the two components independently and present an innovative training schedule that interleaves the training of both modules with shared attention heads. We find that this iterative two part-training results in better performance than a unified network with hierarchical encoding as well as over, other methods that use a {\em record-view} representation of the sequence \cite{de2021transformers4rec} or a simple {\em flattened} representation of the sequence. We conduct experiments using real-world data to demonstrate the advantage of interleaving TVM-KA on multiple tasks and detailed ablation studies motivating our modeling choices. We find that our approach performs better than flattening sequence objects and also allows us to operate on significantly larger sequences than existing methods.
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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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Real-life tools for decision-making in many critical domains are based on ranking results. With the increasing awareness of algorithmic fairness, recent works have presented measures for fairness in ranking. Many of those definitions consider the representation of different ``protected groups'', in the top-$k$ ranked items, for any reasonable $k$. Given the protected groups, confirming algorithmic fairness is a simple task. However, the groups' definitions may be unknown in advance. In this paper, we study the problem of detecting groups with biased representation in the top-$k$ ranked items, eliminating the need to pre-define protected groups. The number of such groups possible can be exponential, making the problem hard. We propose efficient search algorithms for two different fairness measures: global representation bounds, and proportional representation. Then we propose a method to explain the bias in the representations of groups utilizing the notion of Shapley values. We conclude with an experimental study, showing the scalability of our approach and demonstrating the usefulness of the proposed algorithms.
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The previous fine-grained datasets mainly focus on classification and are often captured in a controlled setup, with the camera focusing on the objects. We introduce the first Fine-Grained Vehicle Detection (FGVD) dataset in the wild, captured from a moving camera mounted on a car. It contains 5502 scene images with 210 unique fine-grained labels of multiple vehicle types organized in a three-level hierarchy. While previous classification datasets also include makes for different kinds of cars, the FGVD dataset introduces new class labels for categorizing two-wheelers, autorickshaws, and trucks. The FGVD dataset is challenging as it has vehicles in complex traffic scenarios with intra-class and inter-class variations in types, scale, pose, occlusion, and lighting conditions. The current object detectors like yolov5 and faster RCNN perform poorly on our dataset due to a lack of hierarchical modeling. Along with providing baseline results for existing object detectors on FGVD Dataset, we also present the results of a combination of an existing detector and the recent Hierarchical Residual Network (HRN) classifier for the FGVD task. Finally, we show that FGVD vehicle images are the most challenging to classify among the fine-grained datasets.
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Three main points: 1. Data Science (DS) will be increasingly important to heliophysics; 2. Methods of heliophysics science discovery will continually evolve, requiring the use of learning technologies [e.g., machine learning (ML)] that are applied rigorously and that are capable of supporting discovery; and 3. To grow with the pace of data, technology, and workforce changes, heliophysics requires a new approach to the representation of knowledge.
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In the Earth's magnetosphere, there are fewer than a dozen dedicated probes beyond low-Earth orbit making in-situ observations at any given time. As a result, we poorly understand its global structure and evolution, the mechanisms of its main activity processes, magnetic storms, and substorms. New Artificial Intelligence (AI) methods, including machine learning, data mining, and data assimilation, as well as new AI-enabled missions will need to be developed to meet this Sparse Data challenge.
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