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Imaging Interiors: An Implicit Solution to Electromagnetic Inverse Scattering Problems

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arXiv 2024年

作者： Luo, Ziyuan Shi, Boxin Li, Haoliang Wan, Renjie Department of Computer Science Hong Kong Baptist University Hong Kong National Key Laboratory for Multimedia Information Processing School of Computer Science Peking University China National Engineering Research Center of Visual Technology School of Computer Science Peking University China Department of Electrical Engineering City University of Hong Kong Hong Kong

Electromagnetic Inverse Scattering Problems (EISP) have gained wide applications in computational imaging. By solving EISP, the internal relative permittivity of the scatterer can be non-invasively determined based on the scattered electromagnetic fields. Despite previous efforts to address EISP, achieving better solutions to this problem has remained elusive, due to the challenges posed by inversion and discretization. This paper tackles those challenges in EISP via an implicit approach. By representing the scatterer’s relative permittivity as a continuous implicit representation, our method is able to address the low-resolution problems arising from discretization. Further, optimizing this implicit representation within a forward framework allows us to conveniently circumvent the challenges posed by inverse estimation. Our approach outperforms existing methods on standard benchmark datasets. Copyright © 2024, The Authors. All rights reserved.

关键词： Electromagnetic fields

Three-Dimensional Nuclei Synthesis for Fluorescence Microscopy Image Analysis

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Three-Dimensional Nuclei Synthesis for Fluorescence Microsco...

IEEE International Symposium on Biomedical Imaging

作者： Liming Wu Alain Chen Paul Salama Kenneth W. Dunn Edward J. Delp Video and Image Processing Laboratory School of Electrical and Computer Engineering Purdue University West Lafayette Indiana USA Department of Electrical and Computer Engineering Indiana University-Purdue University Indianapolis Indiana USA Division of Nephrology School of Medicine Indiana University Indianapolis Indiana USA

Three-dimensional tissue cytometry is an important technique for quantitative analysis of cell structures in large fluorescence microscopy volumes. Accurate nuclei detection and segmentation is an important step for 3D tissue cytometry. Deep learning methods have shown promising results for nuclei detection and segmentation. However, manually annotating ground truth for training deep learning methods is labor-intensive and not practical for large 3D volumes. In this paper, we propose a 3D nuclei synthesis method, known as 3DSpCycleGAN, for generating 3D ground truth volumes along with corresponding synthetic microscopy volumes. Experimental results using fluorescence microscopy volumes demonstrate that our method generates more realistic 3D volumes when evaluated both visually and quantitatively than previously reported. We also show that using the synthetic volumes generated by 3DSpCycleGAN as training data improves segmentation accuracy for deep learning segmentation techniques.

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Smooth Attention for Deep Multiple Instance Learning: Application to CT Intracranial Hemorrhage Detection

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arXiv 2023年

作者： Wu, Yunan Castro-Macías, Francisco M. Morales-Álvarez, Pablo Molina, Rafael Katsaggelos, Aggelos K. Image and Video Processing Laboratory Department of Electrical and Computer Engineering Northwestern University United States Department of Computer Science and Artificial Intelligence University of Granada Spain Department of Statistics and Operations Research University of Granada Spain University of Granada Spain

Multiple Instance Learning (MIL) has been widely applied to medical imaging diagnosis, where bag labels are known and instance labels inside bags are unknown. Traditional MIL assumes that instances in each bag are independent samples from a given distribution. However, instances are often spatially or sequentially ordered, and one would expect similar diagnostic importance for neighboring instances. To address this, in this study, we propose a smooth attention deep MIL (SA-DMIL) model. Smoothness is achieved by the introduction of first and second order constraints on the latent function encoding the attention paid to each instance in a bag. The method is applied to the detection of intracranial hemorrhage (ICH) on head CT scans. The results show that this novel SA-DMIL: (a) achieves better performance than the non-smooth attention MIL at both scan (bag) and slice (instance) levels;(b) learns spatial dependencies between slices;and (c) outperforms current state-of-the-art MIL methods on the same ICH test set. Copyright © 2023, The Authors. All rights reserved.

关键词： Diagnosis

A comprehensive review of visualization methods for association rule mining: Taxonomy, Challenges, Open problems and Future ideas

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arXiv 2023年

作者： Fister, Iztok Fister, Iztok Fister, Dušan Podgorelec, Vili Salcedo-Sanz, Sancho Faculty of Electrical Engineering and Computer Science University of Maribor Koroška cesta 46 Maribor2000 Slovenia Department of Signal Processing and Communications Universidad de Alcalá Alcalá de Henares Madrid28805 Spain

Association rule mining is intended for searching for the relationships between attributes in transaction databases. The whole process of rule discovery is very complex, and involves pre-processing techniques, a rule mining step, and post-processing, in which visualization is carried out. Visualization of discovered association rules is an essential step within the whole association rule mining pipeline, to enhance the understanding of users on the results of rule mining. Several association rule mining and visualization methods have been developed during the past decades. This review paper aims to create a literature review, identify the main techniques published in peer-reviewed literature, examine each method’s main features, and present the main applications in the field. Defining the future steps of this research area is another goal of this review paper. Copyright © 2023, The Authors. All rights reserved.

关键词： Visualization

An 0-norm-constrained adaptive algorithm for joint beamforming and antenna selection

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Digital signal processing: A Review Journal 2022年第0期126卷 103475-103475页

作者： Robert, Raimundo Nonato Gonçalves Pitz, Ciro André Batista, Eduardo Luiz Ortiz Seara, Rui LINSE—Circuits and Signal Processing Laboratory Department of Electrical and Electronics Engineering Federal University of Santa Catarina Santa Catarina Florianópolis88040-900 Brazil GEPS—Electronics and Signal Processing Group Department of Control Automation and Computation Engineering Federal University of Santa Catarina Santa Catarina Blumenau89036-004 Brazil

This paper presents a new adaptive algorithm for joint beamforming and antenna selection in mobile communication systems. Such an algorithm is of particular interest for massive multiple-input multiple-output (mMIMO) antenna systems along with limited number of available radio-frequency chains. The proposed algorithm is based on introducing an 0-norm constraint to an established adaptive-projection beamforming optimization scheme. In doing so, a real-time beamforming optimization can be carried out, resulting in a beamforming vector that tends to be sparse. The higher-magnitude elements of such a vector point out to the antenna-array elements that have the largest contribution to the output signal-to-interference-plus-noise ratio (SINR). Consequently, an effective antenna selection can be achieved directly by considering the magnitude of the beamforming coefficients. Simulation results confirm the effectiveness of the proposed algorithm in enhancing the output SINR. © 2022 Elsevier Inc.

关键词： Beamforming

STAR-RIS Enhanced Covert Communication with Delay Constraint

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STAR-RIS Enhanced Covert Communication with Delay Constraint

2023 IEEE/CIC International Conference on Communications in China, ICCC 2023

作者： Cheng, Beixi Hu, Jinsong Chen, Youjia Shu, Feng Chen, Zhizhang David Fuzhou University College of Physics and Information Engineering Fujian Fuzhou350108 China Fujian Key Laboratory for Intelligent Processing and Wireless Transmission of Media Information Fuzhou350108 China Nanjing University of Science and Technology School of Electronic and Optical Engineering Nanjing210094 China Hainan University School of Information and Communication Engineering Haikou570228 China Dalhousie University Department of Electrical and Computer Engineering HalifaxNSB3H 4R2 Canada

ISBN: (纸本)9798350345384

This work confirms the performance gain achieved by deploying a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) in covert communication. To maximize the system covert rate, we jointly optimize the power allocation coefficients at the transmitter and the transmission and reflection coefficients at the STAR-RIS, subject to the delay-constrained and power-constrained. Furthermore, we propose a two-stage alternating optimization algorithm based on the semidefinite relaxation (SDR) method to derive the optimal solutions to the above non-convex optimization problem. The effectiveness and superiority of the proposed algorithm and STAR-RIS-assisted covert scheme are demonstrated by the numerical results. © 2023 IEEE.

关键词： Convex optimization

Defective Microstrip Structure Based Phase Shifter with Reduced Size for Phased Antenna Array Applications

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Defective Microstrip Structure Based Phase Shifter with Redu...

IEEE International Workshop on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications

作者： Hajra Khan Shahid Khan Jamal Nasir Syed Ahson Ali Shah Mariana Dalarsson Mohammad Alibakhshikenari Department of Electrical and Computer Engineering COMSATS University Islamabad Pakistan Applied Bioelectronics Laboratory Hanyang University Seoul South Korea School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden Department of Signal Theory and Communications Universidad Carlos III de Madrid Spain

In this work, we propose a small-size and low-cost phase shifter based on defective microstrip structure (DMS) technique, with a modified reconfigurable unit cell (MRDMS) for WLAN applications at 5.2 GHz. The phase shifter is made up of an MRDMS unit, created by etching slots on a simple microstrip line with an outline of three bridges. To further increase the phase shift, a T-shaped slot is introduced in the central bridge and PIN diodes on the edges of the outer bridges are used. By switching the diodes on and off, the MRDMS unit cell is capable of operating in a variety of different modes to give a phase shift of 37.71° at 5.2 GHz. Additionally, MRDMS unit cells are cascaded for higher phase shift as required. Cascaded two- and four-cell phase shifters were designed and simulated in HFSS and a parametric study on various parameters was conducted to show the detailed operating properties of the proposed phase shifter. Compared to previously reported research, the present study shows that two cascaded phase shifters introduce 75.08° phase shifts and 151.75°, respectively. To the best of our knowledge, this is the maximum phase shift obtained by a phase shifter based on MRDMS.

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Robots Taking Initiative in Collaborative Object Manipulation: Lessons from Physical Human-Human Interaction

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arXiv 2023年

作者： Rysbek, Zhanibek Oh, Ki Hwan Shervedani, Afagh Mehri Klemenčič, Timotej Žefran, Miloš Di Eugenio, Barbara Robotics Lab Department of Electrical and Computer Engineering The University of Illinois at Chicago ChicagoIL60607 United States Laboratory of Robotics Faculty of Electrical Engineering University of Ljubljana Slovenia Natural Language Processing Lab Department of Computer Science The University of Illinois at Chicago ChicagoIL60607 United States

Physical Human-Human Interaction (pHHI) involves the use of multiple sensory modalities. Studies of communication through spoken utterances and gestures are well established, but communication through force signals is not well understood. In this paper, we focus on investigating the mechanisms employed by humans during the negotiation through force signals, and how the robot can communicate task goals, comprehend human intent, and take the lead as needed. To achieve this, we formulate a task that requires active force communication and propose a taxonomy that extends existing literature. Also, we conducted a study to observe how humans behave during collaborative manipulation tasks. An important contribution of this work is the novel features based on force-kinematic signals that demonstrate predictive power to recognize symbolic human intent. Further, we show the feasibility of developing a real-time intent classifier based on the novel features and speculate the role it plays in high-level robot controllers for physical Human-Robot Interaction (pHRI). This work provides important steps to achieve more human-like fluid interaction in physical co-manipulation tasks that are applicable and not limited to humanoid, assistive robots, and human-in-the-loop automation. Copyright © 2023, The Authors. All rights reserved.

关键词： Human robot interaction

Experimental Assessment of Misalignment Effects in Terahertz Communications

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Experimental Assessment of Misalignment Effects in Terahertz...

IEEE International Conference on Communications (ICC)

作者： Hasan Nayir Erhan Karakoca Güneş Karabulut Kurt Ali Görçin Department of Electronics and Communication Engineering İstanbul Technical University İstanbul Turkey Communications and Signal Processing Research (HİSAR) Laboratory TÜBİTAK BİLGEM Kocaeli Turkey Department of Electrical Engineering Poly-Grames Research Center Poly technique Montréal Montréal QC Canada

ISBN: (数字)9781728190549

ISBN: (纸本)9781728190556

Terahertz (THz) frequencies play a crucial role in the advancement of next-generation wireless systems, primarily owing to their substantial available bandwidths. The inherent limitation of limited range, attributed to high attenuation in these frequencies, can be effectively addressed by implementing densely deployed heterogeneous networks, complemented by Unmanned Aerial Vehicles (UAVs) within a three-dimensional hyperspace. Yet, the success of THz communications relies on the precise alignment of beams. Inadequate handling of beam alignment can lead to diminished signal strength at the receiver, significantly affecting THz signals more than their conventional counter-parts. This research underscores the paramount importance of meticulous alignment in THz communication systems. The profound impact of proper alignment is substantiated through comprehensive measurements conducted using a state-of-the-art measurement setup, facilitating accurate data collection across the 240 GHz to 300 GHz spectrum. These measurements encompass varying angles and distances within an anechoic chamber to eliminate reflections. Through a meticulous analysis of the channel frequency and impulse responses derived from these extensive measurements, this study pioneers quantifiable results, providing an assessment of the effects of beam misalignment in THz frequencies.

关键词： Wireless communication Receivers Bandwidth Data collection Autonomous aerial vehicles Reflection Heterogeneous networks