战场互联网事物(IOBT)将提高步兵部队的操作效率。但是,这需要自动资产,例如传感器,无人机,战斗设备和未驾驶的车辆,以合作,安全共享信息,并具有反对攻击的有争议的多域操作中的弹性。 CAPD通过提供背景感知的,政策驱动的框架来解决此问题,该框架支持战争空间中自治实体之间的数据和知识交流。我们提出了一个IOBT本体,该本体促进了受控的信息共享,以实现系统之间的语义互操作性。它的主要贡献包括提供具有共享语义模式的知识图,与背景知识的集成,有效的数据一致性和绘制推断以及支持基于属性的访问控制。 IOBT中的传感器提供了基于本体论创建填充知识图的数据。本文描述了使用CAPD检测和减轻对手动作的方法。 CAPD使用感应的数据和SPARQL查询的推理可以实现情境意识。例如,对手会导致传感器故障或劫持并破坏战术网络以降低视频监视。在这种情况下,CAPD使用基于本体的推理者来查看替代方法如何仍然可以支持任务。根据带宽的可用性,推理器通过主动转码或传输仅静止图像来启动降低的帧速率灰度视频。这种在任务感知环境和攻击环境中推理的能力使自主的IOBT系统能够在有争议的条件下表现出弹性。
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The number of international benchmarking competitions is steadily increasing in various fields of machine learning (ML) research and practice. So far, however, little is known about the common practice as well as bottlenecks faced by the community in tackling the research questions posed. To shed light on the status quo of algorithm development in the specific field of biomedical imaging analysis, we designed an international survey that was issued to all participants of challenges conducted in conjunction with the IEEE ISBI 2021 and MICCAI 2021 conferences (80 competitions in total). The survey covered participants' expertise and working environments, their chosen strategies, as well as algorithm characteristics. A median of 72% challenge participants took part in the survey. According to our results, knowledge exchange was the primary incentive (70%) for participation, while the reception of prize money played only a minor role (16%). While a median of 80 working hours was spent on method development, a large portion of participants stated that they did not have enough time for method development (32%). 25% perceived the infrastructure to be a bottleneck. Overall, 94% of all solutions were deep learning-based. Of these, 84% were based on standard architectures. 43% of the respondents reported that the data samples (e.g., images) were too large to be processed at once. This was most commonly addressed by patch-based training (69%), downsampling (37%), and solving 3D analysis tasks as a series of 2D tasks. K-fold cross-validation on the training set was performed by only 37% of the participants and only 50% of the participants performed ensembling based on multiple identical models (61%) or heterogeneous models (39%). 48% of the respondents applied postprocessing steps.
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Despite the impact of psychiatric disorders on clinical health, early-stage diagnosis remains a challenge. Machine learning studies have shown that classifiers tend to be overly narrow in the diagnosis prediction task. The overlap between conditions leads to high heterogeneity among participants that is not adequately captured by classification models. To address this issue, normative approaches have surged as an alternative method. By using a generative model to learn the distribution of healthy brain data patterns, we can identify the presence of pathologies as deviations or outliers from the distribution learned by the model. In particular, deep generative models showed great results as normative models to identify neurological lesions in the brain. However, unlike most neurological lesions, psychiatric disorders present subtle changes widespread in several brain regions, making these alterations challenging to identify. In this work, we evaluate the performance of transformer-based normative models to detect subtle brain changes expressed in adolescents and young adults. We trained our model on 3D MRI scans of neurotypical individuals (N=1,765). Then, we obtained the likelihood of neurotypical controls and psychiatric patients with early-stage schizophrenia from an independent dataset (N=93) from the Human Connectome Project. Using the predicted likelihood of the scans as a proxy for a normative score, we obtained an AUROC of 0.82 when assessing the difference between controls and individuals with early-stage schizophrenia. Our approach surpassed recent normative methods based on brain age and Gaussian Process, showing the promising use of deep generative models to help in individualised analyses.
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深层生成模型已成为检测数据中任意异常的有前途的工具,并分配了手动标记的必要性。最近,自回旋变压器在医学成像中取得了最先进的性能。但是,这些模型仍然具有一些内在的弱点,例如需要将图像建模为1D序列,在采样过程中误差的积累以及与变压器相关的显着推理时间。去核扩散概率模型是一类非自动回旋生成模型,最近显示出可以在计算机视觉中产生出色的样品(超过生成的对抗网络),并实现与变压器具有竞争力同时具有快速推理时间的对数可能性。扩散模型可以应用于自动编码器学到的潜在表示,使其易于扩展,并适用于高维数据(例如医学图像)的出色候选者。在这里,我们提出了一种基于扩散模型的方法,以检测和分段脑成像中的异常。通过在健康数据上训练模型,然后探索其在马尔可夫链上的扩散和反向步骤,我们可以识别潜在空间中的异常区域,因此可以确定像素空间中的异常情况。我们的扩散模型与一系列具有2D CT和MRI数据的实验相比,具有竞争性能,涉及合成和实际病理病变,推理时间大大减少,从而使它们的用法在临床上可行。
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水生运动是生物学家和工程师感兴趣的经典流体结构相互作用(FSI)问题。求解完全耦合的FSI方程,用于不可压缩的Navier-Stokes和有限的弹性在计算上是昂贵的。在这种系统中,优化机器人游泳器设计通常涉及在已经昂贵的模拟之上繁琐的,无梯度的程序。为了应对这一挑战,我们提出了一种针对FSI的新颖,完全可区分的混合方法,该方法结合了2D直接数值模拟,用于游泳器的可变形固体结构和物理受限的神经网络替代物,以捕获流体的流体动力效应。对于游泳者身体的可变形实心模拟,我们使用来自计算机图形领域的最新技术来加快有限元方法(FEM)。对于流体模拟,我们使用经过基于物理损耗功能的U-NET体系结构来预测每个时间步骤的流场。使用沉浸式边界方法(IBM)在我们游泳器边界的边界周围采样了来自神经网络的压力和速度场输出,以准确有效地计算其游泳运动。我们证明了混合模拟器在2D Carangiform游泳器上的计算效率和可不同性。由于可怜性,该模拟器可用于通过基于直接梯度的优化浸入流体中的软体体系的控件设计。
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We present a dynamic path planning algorithm to navigate an amphibious rotor craft through a concave time-invariant obstacle field while attempting to minimize energy usage. We create a nonlinear quaternion state model that represents the rotor craft dynamics above and below the water. The 6 degree of freedom dynamics used within a layered architecture to generate motion paths for the vehicle to follow and the required control inputs. The rotor craft has a 3 dimensional map of its surroundings that is updated via limited range onboard sensor readings within the current medium (air or water). Path planning is done via PRM and D* Lite.
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This paper presents a machine learning approach to multidimensional item response theory (MIRT), a class of latent factor models that can be used to model and predict student performance from observed assessment data. Inspired by collaborative filtering, we define a general class of models that includes many MIRT models. We discuss the use of penalized joint maximum likelihood (JML) to estimate individual models and cross-validation to select the best performing model. This model evaluation process can be optimized using batching techniques, such that even sparse large-scale data can be analyzed efficiently. We illustrate our approach with simulated and real data, including an example from a massive open online course (MOOC). The high-dimensional model fit to this large and sparse dataset does not lend itself well to traditional methods of factor interpretation. By analogy to recommender-system applications, we propose an alternative "validation" of the factor model, using auxiliary information about the popularity of items consulted during an open-book exam in the course.
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Real-world robotic grasping can be done robustly if a complete 3D Point Cloud Data (PCD) of an object is available. However, in practice, PCDs are often incomplete when objects are viewed from few and sparse viewpoints before the grasping action, leading to the generation of wrong or inaccurate grasp poses. We propose a novel grasping strategy, named 3DSGrasp, that predicts the missing geometry from the partial PCD to produce reliable grasp poses. Our proposed PCD completion network is a Transformer-based encoder-decoder network with an Offset-Attention layer. Our network is inherently invariant to the object pose and point's permutation, which generates PCDs that are geometrically consistent and completed properly. Experiments on a wide range of partial PCD show that 3DSGrasp outperforms the best state-of-the-art method on PCD completion tasks and largely improves the grasping success rate in real-world scenarios. The code and dataset will be made available upon acceptance.
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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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Using Structural Health Monitoring (SHM) systems with extensive sensing arrangements on every civil structure can be costly and impractical. Various concepts have been introduced to alleviate such difficulties, such as Population-based SHM (PBSHM). Nevertheless, the studies presented in the literature do not adequately address the challenge of accessing the information on different structural states (conditions) of dissimilar civil structures. The study herein introduces a novel framework named Structural State Translation (SST), which aims to estimate the response data of different civil structures based on the information obtained from a dissimilar structure. SST can be defined as Translating a state of one civil structure to another state after discovering and learning the domain-invariant representation in the source domains of a dissimilar civil structure. SST employs a Domain-Generalized Cycle-Generative (DGCG) model to learn the domain-invariant representation in the acceleration datasets obtained from a numeric bridge structure that is in two different structural conditions. In other words, the model is tested on three dissimilar numeric bridge models to translate their structural conditions. The evaluation results of SST via Mean Magnitude-Squared Coherence (MMSC) and modal identifiers showed that the translated bridge states (synthetic states) are significantly similar to the real ones. As such, the minimum and maximum average MMSC values of real and translated bridge states are 91.2% and 97.1%, the minimum and the maximum difference in natural frequencies are 5.71% and 0%, and the minimum and maximum Modal Assurance Criterion (MAC) values are 0.998 and 0.870. This study is critical for data scarcity and PBSHM, as it demonstrates that it is possible to obtain data from structures while the structure is actually in a different condition or state.
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