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Neutron transmission imaging system with a superconducting kinetic inductance detector 36

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Neutron transmission imaging system with a superconducting k...

36th International Symposium on Superconductivity, ISS 2023

作者： Dang Vu, The Shishido, Hiroaki Aizawa, Kazuya Oku, Takayuki Oikawa, Kenichi Harada, Masahide Kojima, Kenji M. Miyajima, Shigeyuki Soyama, Kazuhiko Koyama, Tomio Hidaka, Mutsuo Suzuki, Soh Y. Tanaka, Manobu M. Machida, Masahiko Kawamata, Shuichi Ishida, Takekazu Division of Quantum and Radiation Engineering Osaka Metropolitan University Sakai Osaka599-8570 Japan Materials and Life Science Division J-PARC Center Japan Atomic Energy Agency Ibaraki Tokai319-1195 Japan Department of Physics and Electronics Graduate School of Engineering Osaka Metropolitan University Sakai Osaka599-8531 Japan Centre for Molecular and Materials Science TRIUMF 4004 Wesbrook Mall VancouverBCV6T 2A3 Canada Advanced ICT Research Institute National Institute of Information and Communications Technology 588-2 Iwaoka Nishi-ku Hyogo Kobe651-2492 Japan Advanced Industrial Science and Technology Ibaraki Tsukuba305-8568 Japan Ibaraki Tsukuba305-0801 Japan Ibaraki Tsukuba305-0801 Japan Center for Computational Science & E-Systems Japan Atomic Energy Agency 178-4-4 Wakashiba Chiba Kashiwa277-0871 Japan

We optimized the design and operating conditions of our superconducting neutron detector to improve spatial resolution. We obtained the best spatial resolution of 10 μm when a Gd Siemens star pattern was mounted in close contact with the detector. Although there is a trade-off between a spatial resolution and an easiness of replacing samples, we built our superconducting neutron imaging system for measuring in both the room-temperature samples with a proper collimation ratio L/D for achieving a reasonable spatial resolution and a cryogenic temperature with the best spatial resolution for certain purposes. In this study, we obtained neutron transmission images of various samples when they were cooled down with the superconducting neutron detector. We compared the effect of a different sample-detector distance on a spatial resolution when the samples were placed either at cryogenic temperature or at room temperature. We also confirmed that our CB-KID sensor was able to observe the neutron transmission coefficient over wider energies of pulsed neutrons. We found the appearance of clear Bragg dips by the measurements of natural FeS2 single crystals and succeeded in mapping the distribution of differently-oriented crystals by choosing several Bragg dips of the FeS2 crystals to compose the transmission images. © Published under licence by IOP Publishing Ltd.

关键词： Single crystals

Secure Resource Management in Cloud Computing: Challenges, Strategies and Meta-Analysis

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arXiv 2025年

作者： Saxena, Deepika Swain, Smruti Rekha Kumar, Jatinder Patni, Sakshi Gupta, Kishu Singh, Ashutosh Kumar Lindenstruth, Volker Division of Information Systems University of Aizu Aizuwakamatsu9650006 Japan Department of Computer Science The University of Economics and Human Sciences Warsaw01-043 Poland Department of Computer Applications National Institute of Technology Kurukshetra Kurukshetra136119 India Department of Computing Gachon University Seongnam461701 Korea Republic of Department of Computer Science and Engineering National Sun Yat-sen University Kaohsiung804 Taiwan Department of Computer Science and Engineering Indian Institute of Information Technology Bhopal Bhopal462003 India Department of Computer Science and Engineering Goethe University Frankfurt60438 Germany

Secure resource management (SRM) within a cloud computing environment is a critical yet infrequently studied research topic. This paper provides a comprehensive survey and comparative performance evaluation of potential cyber threat countermeasure strategies that address security challenges during cloud workload execution and resource management. Cybersecurity is explored specifically in the context of cloud resource management, with an emphasis on identifying the associated challenges. The cyber threat countermeasure methods are categorized into three classes: defensive strategies, mitigating strategies, and hybrid strategies. The existing countermeasure strategies belonging to each class are thoroughly discussed and compared. In addition to conceptual and theoretical analysis, the leading countermeasure strategies within these categories are implemented on a common platform and examined using two real-world virtual machine (VM) data traces. Based on this comprehensive study and performance evaluation, the paper discusses the trade-offs among these countermeasure strategies and their utility, providing imperative concluding remarks on the holistic study of cloud cyber threat countermeasures and secure resource management. Furthermore, the study suggests future methodologies that could effectively address the emerging challenges of secure cloud resource management. © 2025, CC BY-SA.

关键词： Cloud security

Shotgun crystal structure prediction using machine-learned formation energies

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arXiv 2023年

作者： Liu, Chang Tamaki, Hiromasa Yokoyama, Tomoyasu Wakasugi, Kensuke Yotsuhashi, Satoshi Kusaba, Minoru Oganov, Artem R. Yoshida, Ryo The Institute of Statistical Mathematics Research Organization of Information and Systems Tachikawa Tokyo190-8562 Japan Technology Division Panasonic Holdings Corporation Osaka Kadoma571-8508 Japan Skolkovo Institute of Science and Technology Skolkovo Innovation Center Moscow121205 Russia Department of Statistical Science The Graduate University for Advanced Studies Tachikawa190-8562 Japan

Stable or metastable crystal structures of assembled atoms can be predicted by finding the global or local minima of the energy surface within a broad space of atomic configurations. Generally, this requires repeated first-principles energy calculations, which is often impractical for large crystalline systems. Here, we present significant progress toward solving the crystal structure prediction problem: we performed noniterative, single-shot screening using a large library of virtually created crystal structures with a machine-learning energy predictor. This shotgun method (ShotgunCSP) has two key technical components: transfer learning for accurate energy prediction of pre-relaxed crystalline states, and two generative models based on element substitution and symmetry-restricted structure generation to produce promising and diverse crystal structures. First-principles calculations were performed only to generate the training samples and to refine a few selected pre-relaxed crystal structures. The ShotunCSP method is computationally less intensive than conventional methods and exhibits exceptional prediction accuracy, reaching 93.3% in benchmark tests with 90 different crystal structures. Copyright © 2023, The Authors. All rights reserved.

关键词： Crystal symmetry

Urban Damage Detection Using Temporally Stacked Synthetic Aperture Radar Interferometric Coherence

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Urban Damage Detection Using Temporally Stacked Synthetic Ap...

IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Ryo Natsuaki Ryu Sugimoto Masanobu Shimada Chiaki Tsutsumi Ryosuke Nakamura Department of Electrical Engineering and Information Systems The University of Tokyo Japan Digital Architecture Research Center National Institute of Advanced Industrial Science and Technology Japan Division of Architectural Civil and Environmental Engineering Tokyo Denki University Japan

In this paper, we propose a novel disaster damage detection method using Synthetic Aperture Radar (SAR) interferometric analysis. SAR interferometric coherence analysis is an effective method for disaster monitoring especially in the urban area, where the amplitude of SAR image changes only slightly unless the damage level is high. One drawback of the interferometric coherence-based analysis is the existence of the Cramér-Rao lower bound. That is, a small spatial window for its ensemble averaging leads significant bias while a large window makes its spatial resolution worse. To solve this problem, we propose to extend the ensemble average window towards temporal domain by increasing the number of interferometric pairs. Conventional methods which use multiple interferometric pairs firstly calculate coherence values independently. Instead, the proposed method unifies the interferograms first. We report some preliminary experimental results showing the effectiveness of the proposed method.

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A Wavelet-Based Real-Time Fire Detection with Multi-Modeling Framework

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SSRN

SSRN 2023年

作者： Baek, Jaeseung Alhindi, Taha J. Jeong, Young-Seon Jeong, Myong K. Seo, Seongho Kang, Jongseok Shim, We Heo, Yoseob Department of Industrial and Systems Engineering Rutgers The State University of New Jersey PiscatawayNJ08854 United States Division of Data Analysis Korea Institute of Science and Technology Information Dongdaemun-gu Seoul02456 Korea Republic of

This paper presents a wavelet-based real-time automated fire detection algorithm that considers the multi-resolution property of the wavelet transforms. Unlike conventional fire detection algorithms, which fail to capture temporal dependency within the fire sensor signals, the proposed wavelet-based features characterize the temporal dynamics of sensor signals generated from various types of fire. Then, a real-time fire detection algorithm with a multi-modeling framework is developed to effectively utilize the selected features and construct multiple fire detectors that are sensitive in monitoring various kinds of fires without prior knowledge. In addition, we develop a novel multi-sensor fusion system which incorporates various chemical sensors and collects accurate and reliable fire dataset from different real-life fire scenarios to validate the performance of the proposed and existing fire detection algorithms. The experimental results with real-life and public fire data show that the proposed algorithm outperforms others with early detection time and reasonable false alarm rate. © 2023, The Authors. All rights reserved.

关键词： Wavelet transforms

Robust Data-Driven Predictive Control of Unknown Nonlinear systems using Reachability Analysis

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arXiv 2022年

作者： Farjadnia, Mahsa Alanwar, Amr Niazi, Muhammad Umar B. Molinari, Marco Johansson, Karl Henrik Department of Energy Technology School of Industrial Engineering and Management KTH Royal Institute of Technology Stockholm Sweden School of Computer Science and Engineering Constructor University Bremen Germany Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden Laboratory for Information and Decision Systems Massachusetts Institute of Technology Cambridge United States

This work proposes a robust data-driven predictive control approach for unknown nonlinear systems in the presence of bounded process and measurement noise. Data-driven reachable sets are employed for the controller design instead of using an explicit nonlinear system model. Although the process and measurement noise are bounded, the statistical properties of the noise are not required to be known. By using the past noisy input-output data in the learning phase, we propose a novel method to over-approximate exact reachable sets of an unknown nonlinear system. Then, we propose a data-driven predictive control approach to compute safe and robust control policies from noisy online data. The constraints are guaranteed in the control phase with robust safety margins by effectively using the predicted output reachable set obtained in the learning phase. Finally, a numerical example validates the efficacy of the proposed approach and demonstrates comparable performance with a model-based predictive control approach. Copyright © 2022, The Authors. All rights reserved.

关键词： Nonlinear systems

“I Don’t Want People to Look At Me Differently”: Designing User-Defined Above-the-Neck Gestures for People with Upper Body Motor Impairments 22

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“I Don’t Want People to Look At Me Differently”: Designin...

Proceedings of the 2022 CHI Conference on Human Factors in Computing systems

作者： Xuan Zhao Mingming Fan Teng Han School of Information Rochester Institute of Technology United States Computational Media and Arts Thrust The Hong Kong University of Science and Technology (Guangzhou) China and Division of Integrative Systems and Design The Hong Kong University of Science and Technology Hong Kong Institute of Software Chinese Academy of Sciences China

ISBN: (纸本)9781450391573

Recent research proposed eyelid gestures for people with upper-body motor impairments (UMI) to interact with smartphones without finger touch. However, such eyelid gestures were designed by researchers. It remains unknown what eyelid gestures people with UMI would want and be able to perform. Moreover, other above-the-neck body parts (e.g., mouth, head) could be used to form more gestures. We conducted a user study in which 17 people with UMI designed above-the-neck gestures for 26 common commands on smartphones. We collected a total of 442 user-defined gestures involving the eyes, the mouth, and the head. Participants were more likely to make gestures with their eyes and preferred gestures that were simple, easy-to-remember, and less likely to draw attention from others. We further conducted a survey (N=24) to validate the usability and acceptance of these user-defined gestures. Results show that user-defined gestures were acceptable to both people with and without motor impairments.

关键词： gesture elicitation people with motor impairments user-defined gestures above-the-neck gestures

Policy Evaluation in Distributional LQR

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arXiv 2023年

作者： Wang, Zifan Gao, Yulong Wang, Siyi Zavlanos, Michael M. Abate, Alessandro Johansson, Karl H. Division of Decision and Control Systems KTH Royal Institute of Technology Sweden Department of Computer Science University of Oxford United Kingdom Information-oriented Control Technical University of Munich Germany Department of Mechanical Engineering and Materials Science Duke University United States

Distributional reinforcement learning (DRL) enhances the understanding of the effects of the randomness in the environment by letting agents learn the distribution of a random return, rather than its expected value as in standard RL. At the same time, a main challenge in DRL is that policy evaluation in DRL typically relies on the representation of the return distribution, which needs to be carefully designed. In this paper, we address this challenge for a special class of DRL problems that rely on discounted linear quadratic regulator (LQR) for control, advocating for a new distributional approach to LQR, which we call distributional LQR. Specifically, we provide a closed-form expression of the distribution of the random return which, remarkably, is applicable to all exogenous disturbances on the dynamics, as long as they are independent and identically distributed (i.i.d.). While the proposed exact return distribution consists of infinitely many random variables, we show that this distribution can be approximated by a finite number of random variables, and the associated approximation error can be analytically bounded under mild assumptions. Using the approximate return distribution, we propose a zeroth-order policy gradient algorithm for risk-averse LQR using the Conditional Value at Risk (CVaR) as a measure of risk. Numerical experiments are provided to illustrate our theoretical results. © 2023, CC BY.

关键词： Reinforcement learning

Feasibility Guaranteed Traffic Merging Control Using Control Barrier Functions

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arXiv 2022年

作者： Xu, Kaiyuan Xiao, Wei Cassandras, Christos G. Division of Systems Engineering Center for Information and Systems Engineering Boston University BrooklineMA02446 United States Computer Science and Artificial Intelligence Lab Massachusetts Institute of Technology United States

We consider the merging control problem for Connected and Automated Vehicles (CAVs) aiming to jointly minimize travel time and energy consumption while providing speed-dependent safety guarantees and satisfying velocity and acceleration constraints. Applying the joint optimal control and control barrier function (OCBF) method, a controller that optimally tracks the unconstrained optimal control solution while guaranteeing the satisfaction of all constraints is efficiently obtained by transforming the optimal tracking problem into a sequence of quadratic programs (QPs). However, these QPs can become infeasible, especially under tight control bounds, thus failing to guarantee safety constraints. We solve this problem by deriving a control-dependent feasibility constraint corresponding to each CBF constraint which is added to each QP and we show that each such modified QP is guaranteed to be feasible. Extensive simulations of the merging control problem illustrate the effectiveness of this feasibility guaranteed controller. Copyright © 2022, The Authors. All rights reserved.

关键词： Quadratic programming