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Guiding human movements using tactile information is one of the promising applications of haptics. Using midair ultrasonic haptic stimulation, it is possible to guide a hand without visual information.However, the information of movement shown by conventional methods was partial. It has not been shown a method to guide a hand to an arbitrary point in three dimensional space. In this study, we propose a method of guiding the hand to the top of a virtual cone presented haptically and evaluate the effectiveness of the method through experiments. As a result, the method guided the participant's hand to the goal in a 30 cm cube workspace with an error of 64.34 mm

A noncontact tactile stimulus can be presented by focusing airborne ultrasound on the human skin. Focused ultrasound has recently been reported to produce not only vibration but also static pressure sensation on the palm by modulating the sound pressure distribution at a low frequency. This finding expands the potential for tactile rendering in ultrasound haptics as static pressure sensation is perceived with a high spatial resolution. In this study, we verified that focused ultrasound can render a static pressure sensation associated with contact with a small convex surface on a finger pad. This static contact rendering enables noncontact tactile reproduction of a fine uneven surface using ultrasound. In the experiments, four ultrasound foci were simultaneously and circularly rotated on a finger pad at 5~Hz. When the orbit radius was 3~mm, vibration and focal movements were barely perceptible, and the stimulus was perceived as static pressure. Moreover, under the condition, the pressure sensation rendered a contact with a small convex surface with a radius of 2~mm. The perceived intensity of the static contact sensation was equivalent to a physical contact force of 0.24~N on average, which was 12 times the radiation force physically applied to the skin.

The presentation of a moving tactile stimulus to a person's forearm evokes a pleasant sensation. The speed, intensity, and contact area of the strokes should be systematically changed to evaluate the relationship between pleasantness and tactile stimuli in more detail. Studies have examined the relationship between stroking stimulation and pleasant sensations using airborne ultrasound tactile displays. The ultrasound-based method has the advantage of reproducible control of the speed, intensity, and contact area of the stimulus. In this study, we prepared new stimuli focusing on the modulation methods and the contact area and aimed to clarify their relationship with pleasantness in more detail. Evaluating subjective sensations, such as pleasantness, numerically and consistently is challenging, warranting evaluation based on comparison. We propose a stimulus evaluation method that combines rough evaluation using Likert scales, detailed evaluation using pairwise comparisons, and quantification of comparison data using the Bradley--Terry model. As a result, we confirmed that the stimulus using lateral modulation and that with a large contact area used in this study were more pleasant than the conventional stimulus for six out of ten participants., Comment: 6 pages, 6 figures

Thermoacoustics, the interaction between heat and acoustic waves, is used in a wide range of advanced technological applications. Conversion of ultrasound waves into heat is employed in medical applications, including tumor ablation. However, thermal responses to airborne ultrasounds have not been extensively studied. Herein, we show that thermal responses to high-intensity airborne ultrasounds above 1000 Pa can be used for acoustic measurements. Thermal images on a mesh screen enabled the real-time visualization of three-dimensional acoustic fields. Based on the temperature distribution on a surface that reflects ultrasound waves, it was possible to determine the ultrasound focus position with a resolution much finer than the wavelength. Our results demonstrate that thermography observations based on ultrasound-temperature conversion can be used to visualize acoustic fields, which are conventionally difficult to observe. Our findings will advance technologies that use strong airborne ultrasound, such as mid-air haptics and acoustic levitation, and provide new scientific and technical tools for detecting surface properties and composition, including cells and fragile materials., Comment: 12 pages, 4 figures

第22回宇宙科学シンポジウム (2022年1月6日-7日. オンライン開催), 22nd Space Science Symposium (January 6-7, 2022. Online Meeting), 著者人数: 17名, 資料番号: SA6000176050, レポート番号: P-013

第22回宇宙科学シンポジウム (2022年1月6日-7日. オンライン開催), 22nd Space Science Symposium (January 6-7, 2022. Online Meeting), 著者人数: 47名, 資料番号: SA6000176015, レポート番号: S4-002

第21回宇宙科学シンポジウム (2021年1月6日-7日. オンライン開催), 21st Space Science Symposium (January 6-7, 2021. Online Meeting), 資料番号: SA6000163121, レポート番号: g19-1

第20回宇宙科学シンポジウム (2020年1月8日-9日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 20th Space Science Symposium (January 8-9, 2020. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 17名, 資料番号: SA6000152084, レポート番号: P1.58

第20回宇宙科学シンポジウム (2020年1月8日-9日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 20th Space Science Symposium (January 8-9, 2020. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 41名, 資料番号: SA6000152007, レポート番号: S3-002

EQUULEUS is a spacecraft to explore the cislunar region including the Earth-Moon Lagrange point L2 (EML2) and will be launched by NASA’s SLS EM-1 rocket. Although the size of EQUULEUS is only 6U, the spacecraft carries three different science instruments. By using these instruments, the spacecraft will demonstrate three missions for solar system exploration science during and after the flight to EML2; imaging of the plasmasphere around the earth, observation of space dust flux in the cislunar region, and observation of lunar impact flashes at the far side of the moon. The developments and verifications of the flight models of these science instruments were completed by the end of 2018, and we started flight model integration and testing. This paper introduces the details of the scientific objectives, design results and development statuses of the instruments. In addition, results of the integration and pre-flight tests are also described.

第19回宇宙科学シンポジウム (2019年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 19th Space Science Symposium (January 9-10, 2019. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 37名, 資料番号: SA6000144157, レポート番号: P-123

第28回アストロダイナミクスシンポジウム (2018年7月30-31日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, The 28th Workshop on JAXA Astrodynamics and Flight Mechanics 2018 (July 30-31, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 13名, 資料番号: SA6000135058, レポート番号: C-5

An analytical expression for the polarizability dependent self-diffusion coefficient has been obtained by using a modified version of Zwanzing model for the velocity autocorrelation function. The model indicates that the ion transport coefficient increases with the polarizability.

通常の繰り返しゲームと違って，実際の社会では約束を破って逃げることが可能であることが多い．本稿ではプレイヤーが合意しないとゲームが継続できないというルールの下で，囚人のジレンマを自発的に繰り返すパートナーシップが生成・消滅する社会ゲームのモデルを構築し，モラル・ハザードが起きやすい状況において，どのような社会的制裁の仕組みがそれを防止するかを分析した．結論は三つある．第一に，逃げることが可能な場合でも，信頼構築によって自発的協力が可能になること．第二に，複数の戦略が共存する社会においては必要な信頼構築期間が短縮できること．第三に，やむを得ない事情でパートナーシップが崩壊した場合はその情報が伝わるという紹介状を導入することも，信頼構築期間を短縮することである．これにより，逃げることが可能であっても社会的規範を強制することが可能であり，しかも多様な戦略の共存はむしろ効率性を高めることがわかった．, Unlike the ordinary repeated games, in the real world, people can run away after cheating. In this paper we construct a social game, in which players can repeat Prisoners' Dilemma only if both players agree to continue the partnership. We investigate how a social sanction prevents moral hazard in such a voluntary relationship. We have three conclusions. First, it is possible to enforce voluntary long-term cooperation by trust-building. Second, the trust-building periods can be shortened under diverse strategy distributions. Third, if there is a reference letter system which conveys information that a partnership ended due to an unavoidable cause, then the trust-building periods can be shortened as well.

民主化に先駆けて工業化を行う経済開発戦略を「開発国家戦略」として定義した上で，このような戦略が有効に働く経済環境を分析する．途上国段階ではこの戦略はきわめて有効だが，工業化によって成長した国家では，民主化をしない「強権的政府」は一部の既得権益層に「キャプチャー」され，自ら民主化するインセンティブを持たないために経済危機を引き起こしやすいことを論証する．現代日本で進行中の行政改革を，強権国家としての日本政府を民主化するための自発的な動きとしてとらえ，行政改革が強権国家を民主化するために必要な要因を分析する．, We define the "Developmental State Strategy" as a strategy to industrialize the country before democratization. Types of state system, developmental stages and international environments that are complementary to this strategy are identified. This strategy is quit effective in earlier stages of economic development. However, once the country succeeds in economic development, any "authoritarian government" without democratization is likely to be "captured" by vested interests and to induce crises because there is no incentive to democratize the country within its system. The administrative reform, which is currently proceeding in Japan, should be regarded as a spontaneous effort to democratize the country. We examine the necessary factors that make such an administrative reform to democratize the authoritarian government.

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In today's science-driven industries, such as the semiconductor industry, firms are increasingly engaged in across-firm research and development projects in the form of a research consortium or a strategic alliance. Those collaboration processes, however, have complex aspects due to the competing relationship of the firms in product markets and will not be successful unless the participating firms have enough incentives to reveal their private information and to exert sufficient efforts. The paper attempts to explore the conditions under which firms have enough incentives to reveal their information and/or to expend collaborative efforts. Three existing economic models are examined for this purpose. It is argued that those incentives depend upon the nature of competition in the product markets, information structure, and the way that each firm's private information affects this competition. The models examined in the paper suggest that some mechanism is necessary to evaluate private technical information of each firm and to convey it to the other firms without distortion. This conclusion coincides with the observed fact that a neutral third-party plays an indispensable role in a successful research consortium.

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