1,964 research outputs found
Human Treelike Tubular Structure Segmentation: A Comprehensive Review and Future Perspectives
Various structures in human physiology follow a treelike morphology, which
often expresses complexity at very fine scales. Examples of such structures are
intrathoracic airways, retinal blood vessels, and hepatic blood vessels. Large
collections of 2D and 3D images have been made available by medical imaging
modalities such as magnetic resonance imaging (MRI), computed tomography (CT),
Optical coherence tomography (OCT) and ultrasound in which the spatial
arrangement can be observed. Segmentation of these structures in medical
imaging is of great importance since the analysis of the structure provides
insights into disease diagnosis, treatment planning, and prognosis. Manually
labelling extensive data by radiologists is often time-consuming and
error-prone. As a result, automated or semi-automated computational models have
become a popular research field of medical imaging in the past two decades, and
many have been developed to date. In this survey, we aim to provide a
comprehensive review of currently publicly available datasets, segmentation
algorithms, and evaluation metrics. In addition, current challenges and future
research directions are discussed.Comment: 30 pages, 19 figures, submitted to CBM journa
How to Achieve End-to-end Key Distribution for QKD Networks in the Presence of Untrusted Nodes
Quantum key distribution (QKD) networks are expected to enable
information-theoretical secure (ITS) communication over a large-scale network.
Most researches on relay-based QKD network assume that all relays are
completely trustworthy, but the assumption is unrealistic in a complex network.
The current study only analyzes the case of passive attacks by untrusted relays
(e.g. eavesdropping). However, active attacks by untrusted relays (e.g.
spoofing or interfering with the cooperation between honest nodes) are more
serious threats and should not be ignored. Taking both passive and active
attacks into account, we propose the ITSBFT-QKD networks to defend against
untrusted nodes and achieve end-to-end key distribution. In end-to-end key
distribution, multiple participating nodes are required to establish trust
relationships and cooperate with each other. To prevent attackers from breaking
trust relationship and gaining an unreasonable advantage, we incorporate a
byzantine consensus scheme to establish and transmit trust relationships in a
global QKD network perspective. Moreover, since the security of traditional
consensus schemes is lower than the security requirement of QKD networks, we
devise a byzantine fault tolerance (BFT) signature scheme to ensure the
information-theoretic security of consensus. It provides a new way to construct
signature schemes with point-to-point QKD keys in the presence of untrusted
relays or nodes. The security of our scheme is analyzed thoroughly from
multiple aspects. Our scheme can accommodate up to untrusted nodes, where is the node
connectivity of the network and is the number of nodes in the network. Our
scheme provides the highest level of security in currently relay-based QKD
networks and will significantly promote the application of QKD networks.Comment: 13 pages,7 figure
Large-Kernel Attention for 3D Medical Image Segmentation
Automatic segmentation of multiple organs and tumors from 3D medical images
such as magnetic resonance imaging (MRI) and computed tomography (CT) scans
using deep learning methods can aid in diagnosing and treating cancer. However,
organs often overlap and are complexly connected, characterized by extensive
anatomical variation and low contrast. In addition, the diversity of tumor
shape, location, and appearance, coupled with the dominance of background
voxels, makes accurate 3D medical image segmentation difficult. In this paper,
a novel large-kernel (LK) attention module is proposed to address these
problems to achieve accurate multi-organ segmentation and tumor segmentation.
The advantages of convolution and self-attention are combined in the proposed
LK attention module, including local contextual information, long-range
dependence, and channel adaptation. The module also decomposes the LK
convolution to optimize the computational cost and can be easily incorporated
into FCNs such as U-Net. Comprehensive ablation experiments demonstrated the
feasibility of convolutional decomposition and explored the most efficient and
effective network design. Among them, the best Mid-type LK attention-based
U-Net network was evaluated on CT-ORG and BraTS 2020 datasets, achieving
state-of-the-art segmentation performance. The performance improvement due to
the proposed LK attention module was also statistically validated.Comment: 22 pages, 5 figures, submitted to Cognitive Computatio
On the inverse design of discontinuous abrasive surface to lower friction-induced temperature in grinding: an example of engineered abrasive tools
In order to lower temperature, abrasive tools with passive-grinding, e.g. textured, areas (PGA) have been suggested. However, most of the reported PGA geometries (e.g. slots, holes) have been determined based on the engineering intuition (i.e. trial and error) rather than in-depth phenomenological analysis. To fill this gap, this paper proposes a method to design the PGA geometry according to the desired temperature, i.e. the inverse design method. In the method, the analytical model of grinding temperature for tools with PGA is established and treated as the primary constraint in the inverse problem, while the models of the ground surface roughness and grinding continuity as the subsidiary constraints. The method accuracy is validated by conducting grinding trials with tools with the calculated PGA geometries and comparing their performances (temperature, roughness and force fluctuation) to the required ones. In comparison with conventional tools, our tools designed by the method have been found effective to reduce harmful, or even destructive, thermal effects on the ground surfaces. This work might lay foundation for designing discontinuous abrasive tools, and future work can be probably extended to the tools or the workpiece with more complex shapes (e.g. ball end/cup tools, and free-form workpiece)
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