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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

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

ISBN: (数字)9798350360325

ISBN: (纸本)9798350360332

Interferometric SAR time series analysis using multilooked interferograms has measured ground deformation with high accuracy over large areas, but is known to be contaminated by a systematic bias when using only short-term interferograms. This bias, also referred to as a "fading signal", has been investigated using the abundant time series data from Sentinel-1 C-band SAR, and soil moisture and biomass changes have been suggested as two possible causes for the observed bias. Several correction methods have been proposed to mitigate the phase bias, assuming a periodic observation strategy. The phase bias is supposed to increase with the wavelength, but the bias in ALOS-2 L-band SAR has not been investigated in detail because the data distribution policy restricts its users. In addition, these correction methods are not suitable for the infrequently observed data such as ALOS-2. In this paper, we investigated the systematic bias in ALOS-2 multilooked interferograms with respect to various interferometric pairs. We also corrected the phase bias using the noise-filtering technique. The bias in ALOS-2 multilooked interferograms showed >3 mm/year with an average temporal baseline of 144 days, which is equivalent to that of Sentinel-1 with the temporal baseline of 78 days. That is, the bias effect toward the temporal baseline was larger in ALOS-2 than in Sentinel-1. The noise-filtering technique could mitigate the bias with less pairs regardless of land-use.

关键词： Fading channels Systematics Soil measurements Time series analysis Soil moisture Sentinel-1 Geoscience and remote sensing

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Improving the Reliability of Wireless Pressure Sensors by Optimizing the Fabrication Process

Improving the Reliability of Wireless Pressure Sensors by Op...

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IEEE SENSORS

作者： Jinliang Wei Nomin-Erdene Oyunbaatar Dong-Su Kim Lei Wang Yun-Jin Jeong Dong-Weon Lee MEMS Nanotechnology Laboratory School of Mechanical Engineering Chonnam National University Energy & Nano Technology Group Korea Institute of Industrial Technology (KITECH) Department of Automatic Systems Chosun College of Science & Technology Advanced Medical Device Research Center for Cardiovascular Disease Chonnam National University

ISBN: (数字)9798350363517

ISBN: (纸本)9798350363524

Smart stents equipped with LC wireless pressure sensors are currently a hot topic of research, designed to aid in diagnosing in-stent restenosis. The LC wireless pressure sensors, fabricated from SU-8 photoresist, offer exceptional biocompatibility and flexibility, making them suitable for implantation in the human body. However, the softness and heat-induced deformation of photosensitive polymers introduce significant performance variability in the fabricated LC wireless pressure sensors. This variability manifests as differences in initial resonance frequencies, sensitivities, and other performance metrics, which constrain the practical application of this technology. Our study addresses these challenges by implementing air elimination techniques, incorporating open windows, and enlarging capacitor plates. These modifications successfully reduced performance variability to 2.1% in initial resonance frequency and 6.4% in pressure response sensitivity. Consequently, we have demonstrated the fabrication of LC wireless pressure sensors with stable and reliable performance, advancing the feasibility of their application in smart stents for cardiovascular patients

关键词： Wireless communication Pressure sensors Fabrication Wireless sensor networks Sensitivity Resonant frequency Resists Reliability engineering Resonance Plastics

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Waveguide-multiplexed photonic matrix–vector multiplication processor using multiport photodetectors

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Optica 2025年第6期12卷 812-820页

作者： Rui Tang Makoto Okano Chao Zhang Kasidit Toprasertpong Shinichi Takagi Mitsuru Takenaka Department of Electrical Engineering and Information Systems The University of Tokyo Tokyo 113-8656 Japan Photonics-Electronics Integration Research Center National Institute of Advanced Industrial Science and Technology (AIST) Ibaraki 305-8569 Japan takenaka@mosfet.t.u-tokyo.ac.jp

The slowing down of Moore’s law has driven the development of application-specific processors for deep learning. Analog photonic processors offer a promising solution for accelerating matrix–vector multiplications (MVMs) in deep learning by leveraging parallel computations in the optical domain. Intensity-based photonic MVM processors, which do not utilize the phase information of light, are appealing due to their simplified operations. However, existing intensity-based schemes for such processors often employ wavelength multiplexing or mode multiplexing, both of which have limited scalability due to high insertion loss or wavelength crosstalk. In this work, we present a scalable intensity-based photonic MVM processor based on the concept of waveguide multiplexing. This scheme employs multiport photodetectors (PDs) to sum the intensities of multiple optical signals, eliminating the need for multiple wavelengths or modes. A 16-port Ge PD with a 3 dB bandwidth of 11.8 GHz at a bias voltage of ${-}{3}\;{\text{V}}$ is demonstrated, and it can be further scaled up to handle 250 ports while maintaining a 6.1 GHz operation bandwidth. A $4 \times 4$ circuit fabricated on a Si-on-insulator platform is used to perform MVMs in a three-layer neural network designed for classifying Iris flowers, achieving a classification accuracy of 93.3%. Furthermore, the performance of large-scale circuits in a convolutional neural network for Fashion-MNIST is simulated, resulting in a classification accuracy of 90.53%. This work provides a simplified and scalable approach to photonic MVM, laying a foundation for large-scale and multi-dimensional photonic matrix–matrix multiplication in optical neural networks.

关键词： Deep learning Erbium-doped fiber amplifiers Grating coupler Neural networks Optical neural systems Optical signals

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Navigation for precise walking of blind people based on pulling illusion devices embedded in white canes 4

Navigation for precise walking of blind people based on pull...

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4th IEEE Global Conference on Life Sciences and Technologies, LifeTech 2022

作者： Nunokawa, Kiyohiko Tanabe, Takeshi Takizawa, Hotaka Doi, Kouki Ino, Shuichi Tokyo International University School of Human and Social Sciences Kawagoe Japan Industrial Science and Technology Human Informatics and Interaction Research Institute National Institute of Advanced Tsukuba Japan Information and Systems University of Tsukuba Faculty of Engineering Tsukuba Japan National Institute of Special Needs Education Department of Education Information Yokosuka Japan Osaka University Graduate School of Engineering Osaka Japan

ISBN: (纸本)9781665419048

There have been various types of navigation systems for the visually impaired. Many of them were designed to help the visually impaired walk long distances between large landmarks, such as houses and stations. Moreover, short distance navigation is required for the visually impaired. For example, consider a situation where a visually impaired person moves from a table to a counter in a food court. First, he/she can move roughly, but, near the counter, he/she needs to walk carefully not to collide with or pass through the counter. To the best of our knowledge, such a precise navigation has not been focused on in the past. In this study, we proposed a navigation device for precise walking of the visually impaired. The system comprises a white cane and a small vibration actuator embedded in the grip of the white cane. The actuator can generate asymmetric vibrations, enabling the user to feel a pulling illusion. Using this mechanism, the device can notify the user about the directions to walk. In addition, the actuator is so small and light that the user can use the device with one hand, such as the conventional white cane. Besides, we conducted a user study where two sighted participants who wore eye masked and three visually impaired participants walked 10 m to reach a target destination in a corridor environment to evaluate the proposed device's effectiveness. Based on the results, the device can guide the user precisely. © 2022 IEEE.

关键词： Actuators

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Robust adaptive H∞ control for networked uncertain semi-Markov jump nonlinear systems with input quantization

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Science China(Information Sciences) 2022年第8期65卷 285-286页

作者： Shanling DONG Guanrong CHEN Meiqin LIU Zheng-Guang WU College of Electrical Engineering Zhejiang University Department of Electrical Engineering City University of Hong Kong National Laboratory of Industrial Control Technology Institute of Cyber-Systems and ControlZhejiang University Institute for Advanced Study Chengdu University

Dear editor,Markov jump systems(MJSs), as one kind of switched systems, are a good candidate for modeling physical systems subject to abrupt variation in their structures or parameters caused by many reasons such as s...

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Symmetric silicon microring resonator optical crossbar array for accelerated inference and training in deep learning

arXiv

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arXiv 2024年

作者： Tang, Rui Ohno, Shuhei Tanizawa, Ken Ikeda, Kazuhiro Okano, Makoto Toprasertpong, Kasidit Takagi, Shinichi Takenaka, Mitsuru Department of Electrical Engineering and Information Systems The University of Tokyo Tokyo113-8656 Japan Quantum ICT Research Institute Tamagawa University Tokyo194-8610 Japan National Institute of Advanced Industrial Science and Technology Ibaraki305-8568 Japan

Photonic integrated circuits are emerging as a promising platform for accelerating matrix multiplications in deep learning, leveraging the inherent parallel nature of light. Although various schemes have been proposed and demonstrated to realize such photonic matrix accelerators, the in-situ training of artificial neural networks using photonic accelerators remains challenging due to the difficulty of direct on-chip backpropagation on a photonic chip. In this work, we propose a silicon microring resonator (MRR) optical crossbar array with a symmetric structure that allows for simple on-chip backpropagation, potentially enabling the acceleration of both the inference and training phases of deep learning. We demonstrate a 4 × 4 circuit on a Si-on-insulator (SOI) platform and use it to perform inference tasks of a simple neural network for classifying Iris flowers, achieving a classification accuracy of 93.3%. Subsequently, we train the neural network using simulated on-chip backpropagation and achieve an accuracy of 91.1% in the same inference task after training. Furthermore, we simulate a convolutional neural network (CNN) for handwritten digit recognition, using a 9 × 9 MRR crossbar array to perform the convolution operations. This work contributes to the realization of compact and energy-efficient photonic accelerators for deep learning. © 2024, CC BY.

关键词： Optical resonators

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Measurement of Absorption Current of Polyester Coated Enameled Wires with Q(t) Meter

Measurement of Absorption Current of Polyester Coated Enamel...

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International Symposium on Electrical Insulating Materials

作者： Akinao Watanabe Masumi Fukuma Yoitsu Sekiguchi Advanced Electronic and Information Systems Course National Institute of Technology Matsue College Matsue Japan Department of Electrical Engineering and Computer Science National Institute of Technology Matsue College Matsue Japan Energy and Electronics Materials R&D Laboratories Sumitomo Electric Industries Osaka Japan

A Q(t) meter is used to measure electrical properties in insulating materials. Here, Q(t) is the integral value of circuit current with time t. It is possible to measure the Q(t) of the insulation material of a capacitor and a cable by using Q(t) meter. The current through an insulating material is divided into an instantaneous charging current, an absorption current and an equilibrium leakage current. It is considered that the absorption current is related to charge accumulation in the insulating materials. In this paper, an enameled wire (1.6 PEW) is used to prepare a cable sample, the Q(t) of the coated polyester (PEs) is measured, and extraction of absorption current components from measured Q(t) are reported.

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Comparison of Temporal Decorrelation Decay Functions Over Land Cover Types for L- and C-vand SAR

Comparison of Temporal Decorrelation Decay Functions Over La...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

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

ISBN: (数字)9798350360325

ISBN: (纸本)9798350360332

In repeat-pass interferometric synthetic aperture radar (In-SAR), the coherence loss derived from temporal decorrelation can be modeled using an exponential decay function. Many researches have investigated the relationships between decay parameters over various land-cover types for C-band SAR satellites. Although ALOS PALSAR provides many L-band SAR images, its revisit time was insufficient for understanding the rapid exponential drop in temporal decorrelation. Due to the lack of an appropriate archived dataset, analyzing the decay parameters for L-band SAR was a challenging task. In this study, we processed four-year interferometric pairs derived from ALOS-2 PALSAR-2 full-aperture ScanSAR images. This dataset has a 14 day minimum temporal interval. We selected Nairobi, Kenya, in the middle of the East African rift, as the study area and investigated how decay functions differ over multiple land-cover types. In addition, we compared decay models for Sentinel-1 interferograms. This study demonstrates that the decay parameters of L-band coherence completely differs across forest types, whereas C-band coherence is low coherence regardless of forest type.

关键词： Grasslands C-band Vegetation mapping Sentinel-1 Coherence Forestry Radar polarimetry

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Influence of Prior General Knowledge on Older Adults’ Takeover Performance and Attitude Toward Using Conditionally Automated Driving systems 65th

Influence of Prior General Knowledge on Older Adults’ Takeo...

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65th Human Factors and Ergonomics Society Annual Meeting, HFES 2021

作者： Zhou, Huiping Itoh, Makoto Kitazaki, Satoshi Faculty of Engineering Information and Systems University of Tsukuba Tsukuba-city Japan Automotive Human Factors Research Center National Institute of Advanced Industrial Science and Technology Tsukuba-city Japan

ISBN: (纸本)9781713844129

This study aims to investigate the influence of general knowledge, which denotes·driving automation’s taxonomy, definitions, function, driver role, and the request to intervene (RtI), on older adults’ takeover performance when using conditionally driving automation (DA), and to clarify the influence of knowledge on drivers’ attitudes toward DA. We introduced two types of DAs: full range and limited range. A driving simulator (DS) experiment was conducted to collect data, including driving behavior in taking over vehicle control and driver’s subjective evaluation of the DA. Data were collected from 36 elderly (mean age = 71.4±4.8 years) and 36 non-elderly (mean age = 40.8±9.5 years) participants. The results showed significant differences between the elderly and non-elderly, such that educating knowledge had a greater influence on the older adults, that is, instructing knowledge to the drivers contributed to a statistical increase in successful takeover rate from 0.66 to 0.80, but no effect was seen on either the response time or the maximum steering angular velocity. Furthermore, more frequent glance behavior of looking forward from a non-driving related task was observed in the educated groups. Self-rating scores of subjective evaluations revealed that older adults who were given the knowledge had a higher level of trust in and expectation from the DA, and more confidence in comprehending system functions. This study demonstrates the necessity of general knowledge instruction to enhance drivers’ positive attitudes toward DA. © 2021 by Human Factors and Ergonomics Society. All rights reserved.

关键词： Automation

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High-spin Co3+ as a trigger of weak ferromagnetism in Co-substituted BiFeO3

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Physical Review B 2024年第2期110卷 024422-024422页

作者： Koomok Lee Hena Das Yuki Sakai Takumi Nishikubo Kei Shigematsu Daiki Ono Takehiro Koike Naomi Kawamura Masaichiro Mizumaki Naoki Ishimatsu Masaki Azuma Laboratory for Materials and Structures Institute of Innovative Research Kanagawa Institute of Industrial Science and Technology 705-1 Shimoimaizumi Ebina Kanagawa 243-0435 Japan Research Center for Autonomous Systems Materialogy Institute of Innovative Research Next-Generation Eco-Friendly Devices Collaborative Research Cluster 1-1-1 Kouto Sayo Sayo-cho Sayo-gun Hyogo 679-5198 Japan Faculty of Sciences Course for Physical Sciences Graduate School of Advanced Science and Engineering

Electric field control of magnetization is expected to be utilized for energy-efficient nonvolatile magnetic memory application. Co3+-substituted BiFeO3 (BFCO) exhibits both ferroelectric polarization (∼100µC/cm2) and the spin canting induced weakly ferromagnetic moment (∼0.03µB/f.u.) perpendicular to each other at room temperature. Magnetization reversal by electric field was observed in a BFCO thin film. In our previous theoretical calculation, spin canted collinear structure having a weak ferromagnetic moment was stabilized when high-spin Co3+ was substituted in BiFeO3. To confirm the presence of high-spin Co3+ in BFCO, the pressured-induced spin-state transition of Co3+ was investigated by first-principles calculations and Co Kβ synchrotron x-ray emission spectroscopy. We investigated the spin state of Co3+ during the pressure-induced structural transition from R3c to Pnma. As a result, a pressure-induced transition from high-spin to low-spin Co3+ was predicted. Moreover, the presence of high-spin Co3+ at ambient pressure was confirmed in BiFe0.8Co0.2O3 by observing the decrease of Kβ′ peaks of Co Kβ x-ray emission spectra under pressure. This study provides evidence that the weak ferromagnetism of BFCO is attributed to high-spin Co3+ and provides insight that may help to enhance weak magnetization by substitution of other elements.

关键词： Ferroelectricity High-pressure studies Magnetism Multiferroics First-principles calculations

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