Research Profiles

JP

"G" Keywords - 26 Result(s)

G
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 G

[grain boundary character distribution]

Suppression of Intergranular Degradation of Polycrystalline Materials by Grain Boundary Engineering

 
 
 
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特徴・独自性
  • Intergranular degradation often results in decreased lifetime, reliability and economical efficiency of polycrystalline materials. In spite of persistent efforts to prevent such degradation, its complete suppression has not yet been achieved. Grain boundary studies have revealed that coincidence-site-lattice (CSL) boundaries have stronger resistance to intergranular degradations than random boundaries. The concept of ‘grain boundary design and control' has been refined as grain boundary engineering (GBE). GBEed materials which are characterized by high frequencies of CSL boundaries are resistant to intergranular degradations. Our group has achieved very high frequencies of CSL boundaries in commercial stainless steels by GBE. GBEed stainless steels showed significantly stronger resistance to intergranular corrosion (see Figs. 1 and 2), weld-decay, knife-line attack, stress corrosion cracking, liquid-metal embrittlement, radiation damage, etc. and much longer creep life (see Fig. 3) than the unGBEed ones.
実用化イメージ

By using this GBE processing, we expect to conduct effective collaborative research in related fields.

Researchers

Graduate School of Engineering

Yutaka Sato

[grain boundary engineering]

Suppression of Intergranular Degradation of Polycrystalline Materials by Grain Boundary Engineering

 
 
 
NEXT
PREV
特徴・独自性
  • Intergranular degradation often results in decreased lifetime, reliability and economical efficiency of polycrystalline materials. In spite of persistent efforts to prevent such degradation, its complete suppression has not yet been achieved. Grain boundary studies have revealed that coincidence-site-lattice (CSL) boundaries have stronger resistance to intergranular degradations than random boundaries. The concept of ‘grain boundary design and control' has been refined as grain boundary engineering (GBE). GBEed materials which are characterized by high frequencies of CSL boundaries are resistant to intergranular degradations. Our group has achieved very high frequencies of CSL boundaries in commercial stainless steels by GBE. GBEed stainless steels showed significantly stronger resistance to intergranular corrosion (see Figs. 1 and 2), weld-decay, knife-line attack, stress corrosion cracking, liquid-metal embrittlement, radiation damage, etc. and much longer creep life (see Fig. 3) than the unGBEed ones.
実用化イメージ

By using this GBE processing, we expect to conduct effective collaborative research in related fields.

Researchers

Graduate School of Engineering

Yutaka Sato

[Graphene]

Development of Terahertz Semiconductor Devices Using Novel Nano-Heterostructures and Materials and their ICT Applications

 
 
 
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特徴・独自性
  • Terahertz coherent electromagnetic waves are expected to explore the potential application fields of future information and communications technologies. We are developing novel, ultra-broadband integrated signal-processing devices/systems operating in the terahertz frequency regime employing novel semiconductor nano-heterostructures and materials. We are challenging to develop room-temperature operating coherent and intense laser transistors and fast-response and highly sensitive detectors working for the next-generation beyond-5G terahertz wireless communications as well as safety and security terahertz imaging applications.
  • A. Ultimately-fast terahertz transistors utilizing graphene, carbon-based new material, and compound semiconductor heterojunction material systems:
  • Graphene-based novel terahertz photonics devices, breaking through the limit on conventional technology. Recently we have succeeded in single-mode terahertz lasing in a dual-gate graphene-channel laser transistor device at 100K. Moreover, we have succeeded in room-temperature terahertz coherent amplification in a dual-grating-gate graphene channel transistor promoted by current-driven graphene Dirac plasmon instability. The obtained maximal gain of 9% is four times as high as the quantum efficiency limit when terahertz photons interact directly with graphene electrons without excitation of graphene plasmons. These will be big steps towards realization of an intense, room-temperature operating graphene plasmonic terahertz laser transistors.
  • B. Frequency-tunable plasmon-resonant terahertz emitter and detectors and metamaterial circuits:
  • By using an original dual-grating-gate high-electron mobility transistor (DGG-HEMT) structure with InP-based material systems record-breaking ultrahigh-sensitive detection of terahertz radiation have been realized at room temperature.
実用化イメージ

By making full use of these world-leading device/circuit technologies, we are exploring future ultra-broadband 6G- and 7G-class wireless communication systems as well as spectroscopic/imaging systems for safety and security. We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

Researchers

Research Institute of Electrical Communication

Taiichi Otsuji

[green]

Prediction and evaluation of future thermal and wind environments based on CFD, and planning of urban environments adaptable to future climate

 
 
 
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特徴・独自性
  • Numerical simulations of the physical environment of urban outdoor spaces are conducted to predict the physical environment, such as temperature, humidity, wind, and pollutant concentration, and field measurements are conducted to understand the actual physical environment. In addition, the future outdoor environments and heat stroke risks due to global warming are predicted and evaluated.
    Furthermore, the impacts of urban morphology (building shape and layout, street trees, etc.) on the adaptation to severe heat in summer and rare typhoons and floods are evaluated quantitatively.
実用化イメージ

Numerical analysis is used to quantitatively evaluate the "merits and demerits" of designing buildings, planning city blocks and urban areas, and introducing various heat control technologies on the wider thermal environment and the formation of wind ventilation paths, as well as the adverse effects of typhoons and other disasters. The materials for making decisions on whether or not to introduce these technologies are provided.

Researchers

Graduate School of Engineering

Yasuyuki Ishida

[Green Chemistry]

Development of New Reactions Using Organocatalyst

 
 
 
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特徴・独自性
  • Organocatalyst is a synthetically useful catalyst in synthetic organic chemistry, because of the several merits. We have been investigating the development of new and efficient organocatalysts derived from proline. We have already reported the diphenylprolinol silyl ether, which is called as a Jorgensen-Hayashi catalyst, and siloxyproline, which is effective in the presence of water. We have also developed several practical asymmetric catalytic reactions based on the organocatalysts. We also applied these reactions to the total synthesis of natural products and drugs. We have already synthesized Tamiflu in one-pot reaction, and prostaglandin E1 methyl ester via three one-pot procedure.
実用化イメージ

Our newly developed reactions using organocatalysis can be widely used for synthesis of medicines, agrichemicals, and chemical products.

Researchers

Graduate School of Science

Yujiro Hayashi

[Green infrastructure]

Study on Land Use Management and Residential Movement in Tsunami Affected Areas

 
 
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特徴・独自性
  • The study focused on areas affected by the tsunami caused by the Great East Japan Earthquake, and clarified the impact of reconstruction projects on spatial transformation and residents' residential relocation, as well as residents' satisfaction with the projects. In the boundary area of architecture, urban planning, and landscape architecture, we combine qualitative research, such as participatory observation with sociological and local community perspectives, and quantitative research using data obtained in the field. I would like to explore better relationships between people and nature, and propose methods that lead to sustainable urban development.
実用化イメージ

I have practical experience in post-disaster land use and workshops with local residents. I believe that they will be able to make use of their knowledge and experience in the pre-disaster reconstruction efforts in the areas that are expected to be affected by the disaster in the future.

Researchers

Graduate School of Engineering

Shoko Araki

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