著者

Thanh Binh NGUYEN Naobumi MICHISHITA Hisashi MORISHITA Teruki MIYAZAKI Masato TADOKORO

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Communications (ISSN:09168516)

巻号頁・発行日

vol.E105-B, no.3, pp.275-284, 2022-03-01

被引用文献数

1

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We developed a mantle-cloak antenna by controlling the surface reactance of a dielectric-loaded dipole antenna. First, a mantle-cloak antenna with an assumed ideal metasurface sheet was designed, and band rejection characteristics were obtained by controlling the surface reactance of the mantle cloak. The variable range of the frequency spacing between the operating and stopband frequencies of the antenna was clarified by changing the value of the surface reactance. Next, a mantle-cloak antenna that uses vertical strip conductors was designed to clarify the characteristics and operating principle of the antenna. It was confirmed that the stopband frequency was 1130MHz, and the proposed antenna had a 36.3% bandwidth (|S11| ≤ -10dB) from 700 to 1010MHz. By comparing the |S11| characteristics and the input impedance characteristics of the proposed antenna with those of the dielectric-loaded antenna, the effect of the mantle cloak was confirmed. Finally, a prototype of the mantle-cloak antenna that uses vertical strip conductors was developed and measured to validate the simulation results. The measurement results were consistent with the simulation results.

著者

Jian PANG Xueting LUO Zheng LI Atsushi SHIRANE Kenichi OKADA

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Electronics (ISSN:09168516)

巻号頁・発行日

vol.E105-C, no.3, pp.102-109, 2022-03-01

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This paper introduces a high-resolution and compact CMOS switch-type phase shifter (STPS) for the 5th generation mobile network (5G) n260 band. In this work, totally four coarse phase shifting stages and a high-resolution tuning stage are included. The coarse stages based on the bridged-T topology is capable of providing 202.5° phase coverage with a 22.5° tuning step. To further improve the phase shifting resolution, a compact fine-tuning stage covering 23° is also integrated with the coarse stages. Sub-degree phase shifting resolution is realized for supporting the fine beam-steering and high-accuracy phase calibration in the 5G new radio. Simplified phase control algorithm and suppressed insertion loss can also be maintained by the proposed fine-tuning stage. In the measurement, the achieved RMS gain errors at 39 GHz are 0.1 dB and 0.4 dB for the coarse stages and fine stage, respectively. The achieved RMS phase errors at 39 GHz are 3.1° for the coarse stages and 0.1° for the fine stage. Within 37 GHz to 40 GHz, the measured return loss within all phase-tuning states is always better than -14 dB. The proposed phase shifter consumes a core area of only 0.12mm2 with 65-nm CMOS process, which is area-efficient.

著者

Daisuke KANEMOTO Shun KATSUMATA Masao AIHARA Makoto OHKI

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences (ISSN:09168508)

巻号頁・発行日

vol.E103-A, no.12, pp.1647-1654, 2020-12-01

被引用文献数

9

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This paper proposes a novel compressed sensing (CS) framework for reconstructing electroencephalogram (EEG) signals. A feature of this framework is the application of independent component analysis (ICA) to remove the interference from artifacts after undersampling in a data processing unit. Therefore, we can remove the ICA processing block from the sensing unit. In this framework, we used a random undersampling measurement matrix to suppress the Gaussian. The developed framework, in which the discrete cosine transform basis and orthogonal matching pursuit were used, was evaluated using raw EEG signals with a pseudo-model of an eye-blink artifact. The normalized mean square error (NMSE) and correlation coefficient (CC), obtained as the average of 2,000 results, were compared to quantitatively demonstrate the effectiveness of the proposed framework. The evaluation results of the NMSE and CC showed that the proposed framework could remove the interference from the artifacts under a high compression ratio.

著者

Kyohei CHIBA Hiro ITO

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences (ISSN:09168508)

巻号頁・発行日

vol.E105-A, no.3, pp.131-141, 2022-03-01

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The challenges posed by big data in the 21st Century are complex: Under the previous common sense, we considered that polynomial-time algorithms are practical; however, when we handle big data, even a linear-time algorithm may be too slow. Thus, sublinear- and constant-time algorithms are required. The academic research project, “Foundations of Innovative Algorithms for Big Data,” which was started in 2014 and will finish in September 2021, aimed at developing various techniques and frameworks to design algorithms for big data. In this project, we introduce a “Sublinear Computation Paradigm.” Toward this purpose, we first provide a survey of constant-time algorithms, which are the most investigated framework of this area, and then present our recent results on sublinear progressive algorithms. A sublinear progressive algorithm first outputs a temporary approximate solution in constant time, and then suggests better solutions gradually in sublinear-time, finally finds the exact solution. We present Sublinear Progressive Algorithm Theory (SPA Theory, for short), which enables to make a sublinear progressive algorithm for any property if it has a constant-time algorithm and an exact algorithm (an exponential-time one is allowed) without losing any computation time in the big-O sense.

著者

近藤 恵 兒嶋 朋貴 大川 智章 入部 百合絵

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

電子情報通信学会論文誌 D (ISSN:18804535)

巻号頁・発行日

vol.J105-D, no.3, pp.208-216, 2022-03-01

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近年,農業従事者数の減少により少人数で多頭数の家畜を管理するためのモニタリング技術が求められている.本研究では非接触に収集可能な牛の鳴き声を用いたモニタリング技術の構築を目的に,本論文ではモニタリング技術に必要な鳴き声からの個体識別手法について提案する.鳴き声を用いた個体識別の先行研究では,識別率が十分でないことや月齢による鳴き声の音響特性の違いを考慮していない点が課題として挙げられる.本研究では,月齢の異なる雌のホルスタイン種成牛5頭,育成牛9頭と子牛4頭の計18頭から鳴き声を採取し,声帯波長や声道長に関連のある基本周波数やパワー,線形予測残差波形のMFCC(Mel-Frequency Cepstrum Coefficients)などの音響的特徴量を抽出した.これらの特徴量を利用して,SVM(Support Vector Machine)による個体識別を行った結果,先行研究よりも識別率が35%以上向上した.これにより,牛も人と同様に声帯波長や声道長に個体性が含まれていることが明らかとなった.加えて,話者認識に用いられる相対位相を上記の音響的特徴量に加えることで個体識別の向上が確認された.

著者

早川 正士

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

電子情報通信学会論文誌 B (ISSN:13444697)

巻号頁・発行日

vol.J89-B, no.7, pp.1036-1045, 2006-07-01

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近年地震に伴って各種の電磁気現象が発生することが報告されている.すなわち,地圏から直接放射する電磁気現象や地震に伴う大気圏や電離圏のじょう乱などである.本論文では,地震の短期予知の観点から極めて注目されている二つの観測項目;(1) ULF電磁放射(地圏から直接放射される極低周波電磁放射);(2)電離層じょう乱(VLF/LF送信局電波の伝搬異常として検出)を取り上げ,その計測手法や最新の成果までをレビューする.

著者

Hiroto Kuriki Keita Onose Ryota Kimura Ryo Sawai

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

pp.2021ETL0036, (Released:2021-03-29)

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In this letter, we propose and evaluate a new area-based primary protection method for dynamic spectrum access, in which a secondary system uses a frequency band assigned to a primary system while it keeps an aggregate interference below an acceptable level of the primary system. We consider that a location information of a primary system’s reception station (PRS) whose antenna boresight faces towards a moving primary transmission station is ambiguous. To accurately calculate the aggregate interferences from the secondary system to the PRS in such a situation, the proposed method predicts a range of the PRS’s antenna rotation. Our simulation results show that the proposed method can increase availability of the secondary system significantly in a practical urban scenario.

著者

Keita Onose Hiroto Kuriki Ryota Kimura Ryo Sawai

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

pp.2021XBL0065, (Released:2021-04-02)

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In this letter, we propose a new incumbent protection method that considers three-dimensional (3D) aspects of 5G beamforming characteristics in dynamic spectrum access (DSA). We show some computer simulation results in which fixed wireless access (FWA)-based primary system (PS) and 5G-based secondary system (SS) were assumed to be deployed in a 26 GHz band. The results show that the proposed method can increase allowable transmission power of the SS by considering the 3D beamforming aspects, and that PS and SS height deployment information can additionally bring benefits to the proposed method in terms of the allowable transmission power in DSA.

著者

武山 真弓 佐藤 勝 安井 崇 横川 慎二

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

電子情報通信学会論文誌 C (ISSN:13452827)

巻号頁・発行日

vol.J103-C, no.9, pp.387-394, 2020-09-01

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野生鳥獣の駆除とジビエ利活用が全国的な展開を示す中,北海道ではエゾシカの食用としての利用は1割程度であることから,ジビエ利活用促進のための新たな取り組みが必要不可欠である.我々は,電気的な特性からエゾシカのおいしさを評価し,その解析に従来難しいとされてきた等価回路モデルを選定しなくても簡易な近似で等価回路モデルと遜色ない解析結果が得られるという新たな手法を見出した.更に,従来の化学的な手法や官能検査によるおいしさ評価も行い,電気的な特性との相関について検討した.我々の提案する手法は,リアルタイム計測であることから,食品分野などへの応用が大いに期待される.

著者

Rei Furukawa Nobuaki Kubo Ahmed El-Mowafy

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Communications Express (ISSN:21870136)

巻号頁・発行日

vol.9, no.11, pp.529-534, 2020-11-01 (Released:2020-11-01)

参考文献数

4

被引用文献数

1 3

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The reflections and diffractions of global navigation satellite system (GNSS) signals from buildings may produce large measurement errors. Detecting non-line-of-sight signals using 3D maps is a means to detect and exclude satellites with large measurement errors. However, the true position is typically needed for using 3D maps. In this study, we verify the assumption that an approximate user position can be used when using 3D maps. We found that the correct fixed position of real-time kinematic GNSS (RTK-GNSS) could be achieved when approximate positions for RTK-GNSS assisted by 3D maps were within 5-15m from the true position.

著者

Shanting Hu Masashi Takanohashi Xiaodong Gu Akihiro Matsutani Fumio Koyama

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Electronics Express (ISSN:13492543)

巻号頁・発行日

vol.17, no.2, pp.20190688, 2020 (Released:2020-01-25)

参考文献数

30

被引用文献数

3 4

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We propose and demonstrate the lateral integration of a VCSEL and a slow-light VCSEL amplifier with in-plane resonant wavelength detuning design, enabling the unidirectional coupling and stable single-mode operation with good beam quality. The modelling and simulation result of the wavelength detuning and unidirectional coupling is shown. A slow light laterally coupled from the VCSEL to the amplifier can be amplified uniformly when the amplifier is pumped above the threshold current. We also present the experimental data of the beam quality, output power and spectrum. The measured data show the increased single-mode output power with good beam quality in comparison with conventional VCSELs. A record single-mode power (40 mW) with narrow beam divergence (<0.06°) is presented.

著者

Yoshiki Sugitani Keiji Konishi

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

Nonlinear Theory and Its Applications, IEICE (ISSN:21854106)

巻号頁・発行日

vol.12, no.4, pp.612-624, 2021 (Released:2021-10-01)

参考文献数

41

被引用文献数

5

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Delays can have a negative impact on the stability of various systems. However, it was reported that the transmission delays of signals among oscillators can stabilize unstable equilibrium points in coupled oscillators, which is called amplitude death (AD). AD caused by delays has been extensively researched in the field of nonlinear science and has attracted attention for various engineering applications. In this article, we review the latest studies on AD caused by delays in oscillator networks, in particular those that considered heterogeneous delays and time-varying networks.

著者

大石 晴夫 矢守 恭子 張 成 田中 良明

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

電子情報通信学会論文誌 B (ISSN:13444697)

巻号頁・発行日

vol.J105-B, no.1, pp.1-13, 2022-01-01

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複数の通信方式を組み合わせて通信ネットワークを構築するコグニティブネットワークや異種混合ネットワークにおける利用者の協調による効用,コスト削減,インセンティブメカニズムが研究されている.一方,多様な通信方式のサービスが一般に普及している中で,社会環境の変化に対応した協調行動を取り入れ,これらを統合して利用者にサービス提供するフレームワークは提案されていない.本論文では,交通分野におけるサービス提供の概念であるMaaS (Mobility as a Service)に注目し,MaaSのコンセプトを取り込んだSHaaS (Sharing framework for Heterogeneous network as a Service)を提案する.SHaaSにおける事業者と利用者の間のリソース共有により,利用者の効用と事業者の収益の向上を目指す.SHaaSのアーキテクチャ,料金モデルを提案し,モデルに基づくシミュレーションにより有効性を評価した.従来のサービス提供形態と比較して,特にリソース不足の条件下における高い有効性を示した.

著者

Kiyoharu AIZAWA

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Information and Systems (ISSN:09168532)

巻号頁・発行日

vol.E105-D, no.1, pp.38-45, 2022-01-01

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This paper introduces our work on a Movie Map, which will enable users to explore a given city area using 360° videos. Visual exploration of a city is always needed. Nowadays, we are familiar with Google Street View (GSV) that is an interactive visual map. Despite the wide use of GSV, it provides sparse images of streets, which often confuses users and lowers user satisfaction. Forty years ago, a video-based interactive map was created - it is well-known as Aspen Movie Map. Movie Map uses videos instead of sparse images and seems to improve the user experience dramatically. However, Aspen Movie Map was based on analog technology with a huge effort and never built again. Thus, we renovate the Movie Map using state-of-the-art technology. We build a new Movie Map system with an interface for exploring cities. The system consists of four stages; acquisition, analysis, management, and interaction. After acquiring 360° videos along streets in target areas, the analysis of videos is almost automatic. Frames of the video are localized on the map, intersections are detected, and videos are segmented. Turning views at intersections are synthesized. By connecting the video segments following the specified movement in an area, we can watch a walking view along a street. The interface allows for easy exploration of a target area. It can also show virtual billboards in the view.

著者

Yuji ITO Kenji FUJIMOTO

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences (ISSN:09168508)

巻号頁・発行日

vol.E105-A, no.1, pp.1-10, 2022-01-01

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Recently, control theory using machine learning, which is useful for the control of unknown systems, has attracted significant attention. This study focuses on such a topic with optimal control problems for unknown nonlinear systems. Because optimal controllers are designed based on mathematical models of the systems, it is challenging to obtain models with insufficient knowledge of the systems. Kernel functions are promising for developing data-driven models with limited knowledge. However, the complex forms of such kernel-based models make it difficult to design the optimal controllers. The design corresponds to solving Hamilton-Jacobi (HJ) equations because their solutions provide optimal controllers. Therefore, the aim of this study is to derive certain kernel-based models for which the HJ equations are solved in an exact sense, which is an extended version of the authors' former work. The HJ equations are decomposed into tractable algebraic matrix equations and nonlinear functions. Solving the matrix equations enables us to obtain the optimal controllers of the model. A numerical simulation demonstrates that kernel-based models and controllers are successfully developed.

著者

Mitsuhiko Shimomura Nicolas Chauvet Mikio Hasegawa Makoto Naruse

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

Nonlinear Theory and Its Applications, IEICE (ISSN:21854106)

巻号頁・発行日

vol.13, no.1, pp.101-111, 2022 (Released:2022-01-01)

参考文献数

10

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High-bandwidth irregular oscillations caused by optical time-delayed feedback subjected to the laser cavity, known as laser chaos, have been investigated for various engineering applications. Recently, a fast decision-making algorithm for a multi-arm bandit problem by utilizing laser chaos time series has been demonstrated. Furthermore, the arms order recognition of the reward expectation for each arm has been successfully developed by incorporating the notion of the confidence interval regarding the reward estimate. However, in previous studies, the verification was limited to numerical experiments; real-world demonstrations were not conducted. This study experimentally demonstrated that the arm-order recognition algorithm is successfully operated in channel order recognition in wireless communications while revising the original strategy to take into account the wireless application requirements. Such accurate arm rank recognition involving non-best arms would be useful for various real-world applications such as channel bonding, among others.

著者

松村 欣司

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

電子情報通信学会 通信ソサイエティマガジン (ISSN:21860661)

巻号頁・発行日

vol.9, no.3, pp.134-135, 2015

著者

山本 高至 白戸 裕史 内田 大誠 北 直樹

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

電子情報通信学会論文誌 B (ISSN:13444697)

巻号頁・発行日

vol.J104-B, no.12, pp.963-973, 2021-12-01

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無線通信の大容量化に伴い,周波数資源の潤沢なミリ波帯以上の周波数活用の検討が進められている.このような高周波数帯では送受信点間が人体によって遮蔽された程度であっても,従来の移動通信等で用いられてきたUHF帯や低SHF帯に比べて大きなレベル低下を生じるために,基地局-端末間の見通しの確保が重要になる.複数の人が動き回るような環境では,複数の基地局やアンテナによって,いずれかの基地局(アンテナ)と端末間に見通しを確保するためのサイトダイバーシチやスペースダイバーシチ等を目的とした分散アンテナシステムが有効である.アンテナ間の離隔は遮蔽状態の相関に依存するが,これまで遮蔽状態の相関については経験的な検討に留まっていた.本論文では,高周波数帯を用いる通信の人体遮蔽に関して,人体を一様なポアソン点過程と仮定した確率幾何解析により,遮蔽率,ハンドオーバによる回避率,遮蔽の発生有無に関する自己相関関数を導出する.加えて,多数の分散アンテナに対する等価見通し率を示すとともに,解析結果に基づくアンテナの設置法について幾つかの例を示す.

著者

Yasuhisa FUJII Kazumasa YAMAMOTO Seiichi NAKAGAWA

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE Transactions on Information and Systems (ISSN:09168532)

巻号頁・発行日

vol.E95.D, no.4, pp.1101-1111, 2012-04-01 (Released:2012-04-01)

参考文献数

30

被引用文献数

2

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This paper presents a novel method for improving the readability of automatic speech recognition (ASR) results for classroom lectures. Because speech in a classroom is spontaneous and contains many ill-formed utterances with various disfluencies, the ASR result should be edited to improve the readability before presenting it to users, by applying some operations such as removing disfluencies, determining sentence boundaries, inserting punctuation marks and repairing dropped words. Owing to the presence of many kinds of domain-dependent words and casual styles, even state-of-the-art recognizers can only achieve a 30-50% word error rate for speech in classroom lectures. Therefore, a method for improving the readability of ASR results is needed to make it robust to recognition errors. We can use multiple hypotheses instead of the single-best hypothesis as a method to achieve a robust response to recognition errors. However, if the multiple hypotheses are represented by a lattice (or a confusion network), it is difficult to utilize sentence-level knowledge, such as chunking and dependency parsing, which are imperative for determining the discourse structure and therefore imperative for improving readability. In this paper, we propose a novel algorithm that infers clean, readable transcripts from spontaneous multiple hypotheses represented by a confusion network while integrating sentence-level knowledge. Automatic and manual evaluations showed that using multiple hypotheses and sentence-level knowledge is effective to improve the readability of ASR results, while preserving the understandability.

著者

青見 樹 堤 瑛美子 宇都 雅輝 植野 真臣

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

電子情報通信学会論文誌 D (ISSN:18804535)

巻号頁・発行日

vol.J104-D, no.11, pp.784-795, 2021-11-01

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小論文自動採点は,人間評価者に代わって自動採点モデルが小論文の採点を行う自然言語処理におけるタスクの一つである.近年では多くの自動採点モデルが提案されており,それぞれに異なった特徴を有している.本研究では,評価者特性を考慮した項目反応理論を用いて自動採点モデルのモデル平均を行う新たな手法を提案する.具体的には自動採点モデルを一人の評価者とみなして評価者特性を考慮した項目反応モデルを適用することで,それぞれの自動採点モデルの特徴を考慮した統合を行う.実験を通して,提案手法が単体の自動採点モデルや,単純な予測スコアの平均化手法と比べて予測精度を向上させることを示す.更に,提案手法が統合した自動採点モデルの特徴を捉え,安定したスコアの予測を行うことができることを示す.