Hiroshi Yamaguchi - Academia.edu (original) (raw)
Papers by Hiroshi Yamaguchi
Journal of Applied Physics, 2014
Materials Science Forum, 2015
Catalysis Science & Technology, 2011
... 26, K. Sangeetha and TE Abraham, Int. J. Biol. ... 30, BC Kim, D. Lopez-Ferrer, S.-M. Lee, H.... more ... 26, K. Sangeetha and TE Abraham, Int. J. Biol. ... 30, BC Kim, D. Lopez-Ferrer, S.-M. Lee, H.-K. Ahn, S. Nair, SH Kim, BS Kim, K. Petritis, DG Camp, JW Grate, RD Smith, Y.-M. Koo, MB Gu and J. Kim, Proteomics, 2009, 9, 18931900 Article CAS . Footnotes. ...
Advances in Applied Mathematics and Mechanics
Intrigued by our recent experimental work (H. Yamaguchi and X. D. Niu, J. Fluids Eng., 133 (2011)... more Intrigued by our recent experimental work (H. Yamaguchi and X. D. Niu, J. Fluids Eng., 133 (2011), 041302), the present study numerically investigate the flow-structure interactions (FSI) of three rigid circular particles aligned moving in an inclined channel flow at intermediate Reynolds numbers by using a momentum-exchanged immersed boundary-lattice Boltzmann method. A ”frog-leap” phenomenon observed in the experiment is successfully captured by the present simulation and flow characteristics and underlying FSI mechanisms of it are explored by examining the effects of the channel inclined angles and Reynolds numbers. It is found that the asymmetric difference of the vorticity distributions on the particle surface is the main cause of the “frog-leap” when particle moves in the boundary layer near the lower channel boundary.
In the present study we report the flow characteristics of a steady flow of viscoelastic fluid in... more In the present study we report the flow characteristics of a steady flow of viscoelastic fluid in a curved pipe of 90 degree bend. The liquid mode consideration is a model-fluid, which is newly made to investigate the viscoelastic fluid. The flow behavior in the curved pipe was examined by experimentally and analytically at low Reynolds numbers. The visualization of flow in the curved pipe was achieved using a hydrogen bubble method, in which micro-size hydrogen bubbles are generated by a thin platinum wire with passing DC current. The finite element method was used to obtain the analytical solution for the viscoelastic character in the curved pipe. The rheorogical characterization was made by measuring the model-fluid with a precision rheometer. Then the model-fluid was characterized by White-Metzner model and Herschel-Bulkley model as the constitutive equation, for the numerical analysis. The obtained results from the visualization by the hydrogen bubble method were well predicted...
2000 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.00CH37056), 2000
Delay-locked loops (DLLs) are widely used to align signal phases in many high-speed microprocesso... more Delay-locked loops (DLLs) are widely used to align signal phases in many high-speed microprocessors and memories. Phase-locked loops (PLLs) are also used but their jitter is larger than that of DLLs, because DLLs have no jitter accumulation. However, conventional DLLs have design problems. One is that their phase capture ranges are limited, and another is that a special reset sequence
2007 Digest of papers Microprocesses and Nanotechnology, 2007
ABSTRACT In this paper, we demonstrate that a two-dimensional arrangement of vertical cylindrical... more ABSTRACT In this paper, we demonstrate that a two-dimensional arrangement of vertical cylindrical domains of asymmetric poly(styrene-b-methyl methacrylate) (PSt-b-PMMA) is achieved by graphoepitaxy using a resist pattern as the guide for alignment. The key to success is the combination of the neutralization of a bottom surface and the introduction of a two-dimensional hydrophilic guiding pattern, which leads to vertical orientation and lateral arrangement of cylindrical domains, respectively.
Journal of Intelligent Material Systems and Structures, 2009
ABSTRACT
Applied Thermal Engineering
Heat transfer characteristics of supercritical CO2 (S-CO2) fluid in collectors of a solar Rankine... more Heat transfer characteristics of supercritical CO2 (S-CO2) fluid in collectors of a solar Rankine cycle system is experimentally investigated at different flow conditions. In the experiments, temperature, pressure and mass flow rate are measured, and local and average heat transfer coefficients are investigated. Study shows that the thermophysical properties of CO2 near the critical point have significant effects on the S-CO2 local heat transfer behaviors. The heat transfer of S-CO2 is also dependent on the mass flow rate, input heat flux and pressure at inlet of test section.Research highlights► We carried out an experimental investigation of the heat transfer characteristics of S-CO2 in a heating tube in order to obtain the optimized high efficiency operation condition of the solar collector in a proposed S-CO2-based SRCS. ► It is found that the heat transfer of S-CO2 can be enhanced greatly by slightly increasing the mass flow rate. ► Reducing the input heat flux and the inlet pr...
Applied Physics Express, 2014
ABSTRACT A phonon waveguide (WG) constructed via a one-dimensional array of mechanical resonators... more ABSTRACT A phonon waveguide (WG) constructed via a one-dimensional array of mechanical resonators is used to access a localized mechanical resonator. This resonator plays the role of a memory node in which binary information can be written, stored, and read via the mobile mechanical excitations in the phonon WG. The phonon WG-localized resonator architecture demonstrates the viability of mechanical circuits for information processing applications.
Materials Science Forum, 2014
ABSTRACT The energetics for the Si desorption and the C adsorption at a [11-20] step on SiC(0001)... more ABSTRACT The energetics for the Si desorption and the C adsorption at a [11-20] step on SiC(0001) surface are studied using the first-principles calculation. It is found that the [11-20] step is stable and nonreactive. The stability of the step is thought to govern the surface morphology during the graphene formation. It is shown that the Si pressure and the temperature are the control parameters for the surface morphology and the graphene quality.
2014 IEEE International Frequency Control Symposium (FCS), 2014
ABSTRACT Two recent approaches to dynamically convert the phonon frequency using the semiconducto... more ABSTRACT Two recent approaches to dynamically convert the phonon frequency using the semiconductor-based electromechanical resonators are presented. One is coherent phonon manipulation in coupled mechanical resonators and the other is all-mechanical phonon lasing in a mechanical three-level system. The examples demonstrate the high functionality of semiconductor-based electromechanical resonators.
ABSTRACT When an external magnetic field is applied to boiling two-phase flow in a magnetic fluid... more ABSTRACT When an external magnetic field is applied to boiling two-phase flow in a magnetic fluid, it is known to effectively increase the heat transfer of magnetic fluid. In particular, void fraction of vapor two-phase flow plays a important role in understanding the heat transfer characteristics of magnetic fluid. However, there are a few studies to measure the void fraction of magnetic fluid because several conventional measurement techniques are difficult to apply to a magnetic fluid. In the present study, electromagnetic induction method was installed to measure the vapor void fraction and this measurement technique was proved to be valid for measuring void fraction of vapor bubbles. As a result, the present measurement was able to confirm the reduction of vapor void fraction under the influence of an external magnetic field.
Physical review letters, Jan 27, 2015
In this Letter, we propose a counterintuitive use of a hybrid system where the coherence time of ... more In this Letter, we propose a counterintuitive use of a hybrid system where the coherence time of a quantum system can be significantly improved by coupling it with a system of a shorter coherence time. Coupling a two-level system with a single nitrogen-vacancy (NV^{-}) center, a dark state of the NV^{-} center naturally forms after the hybridization. We show that this dark state becomes robust against noise due to the coupling even when the coherence time of the two-level system is much shorter than that of the NV^{-} center. Our proposal opens a new way to use a quantum hybrid system for the realization of robust quantum information processing.
ABSTRACT A Time-resolved Kerr rotation spectroscopy under selective excitation by narrow spectrum... more ABSTRACT A Time-resolved Kerr rotation spectroscopy under selective excitation by narrow spectrum pump beam is applied to high-mobility two dimensional (2D) electrons. The large non-oscillating Kerr signal is ascribed to the formation of Skyrmions by photoexcited carrier, and is confirmed by the selective excitation in TRKR measurement. The collapse of the spin coherence (dip of T2*) near nu = 1 may be related by the formation of Skyrmions and anti-Skyrmiosn pair under photoexcitation.
ABSTRACT The role of the step in the initial stage of graphene growth is focused on, and recipe h... more ABSTRACT The role of the step in the initial stage of graphene growth is focused on, and recipe how to improve the domain size of the grown graphene is discussed based on the first-principles calculations. It is considered that keeping the surface smoothness and limiting the number of C aggregation sites are the keys to improve the domain size.
Physical review letters, Jan 17, 2014
An electromechanical resonator is developed in which mechanical nonlinearities can be dynamically... more An electromechanical resonator is developed in which mechanical nonlinearities can be dynamically engineered to emulate the nondegenerate parametric down-conversion interaction. In this configuration, phonons are simultaneously generated in pairs in two macroscopic vibration modes, resulting in the amplification of their motion. In parallel, two-mode thermal squeezed states are also created, which exhibit fluctuations below the thermal motion of their constituent modes as well as harboring correlations between the modes that become almost perfect as their amplification is increased. The existence of correlations between two massive phonon ensembles paves the way towards an entangled macroscopic mechanical system at the single phonon level.
Methods in molecular biology (Clifton, N.J.), 2012
Proteolysis is the key step for proteomic studies integrated with MS analysis. Compared with the ... more Proteolysis is the key step for proteomic studies integrated with MS analysis. Compared with the conventional method of in-solution digestion, proteolysis by a protease-immobilized microreactor has a number of advantages for proteomic analysis; i.e., rapid and efficient digestion, elimination of a purification step of the digests prior to MS, and high stability against a chemical or thermal denaturant. This chapter describes the preparation of the protease-immobilized microreactors and proteolysis performance of these microreactors. Immobilization of proteases by the formation of a polymeric membrane consisting solely of protease-proteins on the inner wall of the microchannel is performed. This was realized either by a cross-linking reaction in a laminar flow between lysine residues sufficiently present on the protein surfaces themselves or in the case of acidic proteins by mixing them with poly-lysine prior to the crosslink-reaction. The present procedure is simple and widely usefu...
Journal of Applied Physics, 2014
Materials Science Forum, 2015
Catalysis Science & Technology, 2011
... 26, K. Sangeetha and TE Abraham, Int. J. Biol. ... 30, BC Kim, D. Lopez-Ferrer, S.-M. Lee, H.... more ... 26, K. Sangeetha and TE Abraham, Int. J. Biol. ... 30, BC Kim, D. Lopez-Ferrer, S.-M. Lee, H.-K. Ahn, S. Nair, SH Kim, BS Kim, K. Petritis, DG Camp, JW Grate, RD Smith, Y.-M. Koo, MB Gu and J. Kim, Proteomics, 2009, 9, 18931900 Article CAS . Footnotes. ...
Advances in Applied Mathematics and Mechanics
Intrigued by our recent experimental work (H. Yamaguchi and X. D. Niu, J. Fluids Eng., 133 (2011)... more Intrigued by our recent experimental work (H. Yamaguchi and X. D. Niu, J. Fluids Eng., 133 (2011), 041302), the present study numerically investigate the flow-structure interactions (FSI) of three rigid circular particles aligned moving in an inclined channel flow at intermediate Reynolds numbers by using a momentum-exchanged immersed boundary-lattice Boltzmann method. A ”frog-leap” phenomenon observed in the experiment is successfully captured by the present simulation and flow characteristics and underlying FSI mechanisms of it are explored by examining the effects of the channel inclined angles and Reynolds numbers. It is found that the asymmetric difference of the vorticity distributions on the particle surface is the main cause of the “frog-leap” when particle moves in the boundary layer near the lower channel boundary.
In the present study we report the flow characteristics of a steady flow of viscoelastic fluid in... more In the present study we report the flow characteristics of a steady flow of viscoelastic fluid in a curved pipe of 90 degree bend. The liquid mode consideration is a model-fluid, which is newly made to investigate the viscoelastic fluid. The flow behavior in the curved pipe was examined by experimentally and analytically at low Reynolds numbers. The visualization of flow in the curved pipe was achieved using a hydrogen bubble method, in which micro-size hydrogen bubbles are generated by a thin platinum wire with passing DC current. The finite element method was used to obtain the analytical solution for the viscoelastic character in the curved pipe. The rheorogical characterization was made by measuring the model-fluid with a precision rheometer. Then the model-fluid was characterized by White-Metzner model and Herschel-Bulkley model as the constitutive equation, for the numerical analysis. The obtained results from the visualization by the hydrogen bubble method were well predicted...
2000 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.00CH37056), 2000
Delay-locked loops (DLLs) are widely used to align signal phases in many high-speed microprocesso... more Delay-locked loops (DLLs) are widely used to align signal phases in many high-speed microprocessors and memories. Phase-locked loops (PLLs) are also used but their jitter is larger than that of DLLs, because DLLs have no jitter accumulation. However, conventional DLLs have design problems. One is that their phase capture ranges are limited, and another is that a special reset sequence
2007 Digest of papers Microprocesses and Nanotechnology, 2007
ABSTRACT In this paper, we demonstrate that a two-dimensional arrangement of vertical cylindrical... more ABSTRACT In this paper, we demonstrate that a two-dimensional arrangement of vertical cylindrical domains of asymmetric poly(styrene-b-methyl methacrylate) (PSt-b-PMMA) is achieved by graphoepitaxy using a resist pattern as the guide for alignment. The key to success is the combination of the neutralization of a bottom surface and the introduction of a two-dimensional hydrophilic guiding pattern, which leads to vertical orientation and lateral arrangement of cylindrical domains, respectively.
Journal of Intelligent Material Systems and Structures, 2009
ABSTRACT
Applied Thermal Engineering
Heat transfer characteristics of supercritical CO2 (S-CO2) fluid in collectors of a solar Rankine... more Heat transfer characteristics of supercritical CO2 (S-CO2) fluid in collectors of a solar Rankine cycle system is experimentally investigated at different flow conditions. In the experiments, temperature, pressure and mass flow rate are measured, and local and average heat transfer coefficients are investigated. Study shows that the thermophysical properties of CO2 near the critical point have significant effects on the S-CO2 local heat transfer behaviors. The heat transfer of S-CO2 is also dependent on the mass flow rate, input heat flux and pressure at inlet of test section.Research highlights► We carried out an experimental investigation of the heat transfer characteristics of S-CO2 in a heating tube in order to obtain the optimized high efficiency operation condition of the solar collector in a proposed S-CO2-based SRCS. ► It is found that the heat transfer of S-CO2 can be enhanced greatly by slightly increasing the mass flow rate. ► Reducing the input heat flux and the inlet pr...
Applied Physics Express, 2014
ABSTRACT A phonon waveguide (WG) constructed via a one-dimensional array of mechanical resonators... more ABSTRACT A phonon waveguide (WG) constructed via a one-dimensional array of mechanical resonators is used to access a localized mechanical resonator. This resonator plays the role of a memory node in which binary information can be written, stored, and read via the mobile mechanical excitations in the phonon WG. The phonon WG-localized resonator architecture demonstrates the viability of mechanical circuits for information processing applications.
Materials Science Forum, 2014
ABSTRACT The energetics for the Si desorption and the C adsorption at a [11-20] step on SiC(0001)... more ABSTRACT The energetics for the Si desorption and the C adsorption at a [11-20] step on SiC(0001) surface are studied using the first-principles calculation. It is found that the [11-20] step is stable and nonreactive. The stability of the step is thought to govern the surface morphology during the graphene formation. It is shown that the Si pressure and the temperature are the control parameters for the surface morphology and the graphene quality.
2014 IEEE International Frequency Control Symposium (FCS), 2014
ABSTRACT Two recent approaches to dynamically convert the phonon frequency using the semiconducto... more ABSTRACT Two recent approaches to dynamically convert the phonon frequency using the semiconductor-based electromechanical resonators are presented. One is coherent phonon manipulation in coupled mechanical resonators and the other is all-mechanical phonon lasing in a mechanical three-level system. The examples demonstrate the high functionality of semiconductor-based electromechanical resonators.
ABSTRACT When an external magnetic field is applied to boiling two-phase flow in a magnetic fluid... more ABSTRACT When an external magnetic field is applied to boiling two-phase flow in a magnetic fluid, it is known to effectively increase the heat transfer of magnetic fluid. In particular, void fraction of vapor two-phase flow plays a important role in understanding the heat transfer characteristics of magnetic fluid. However, there are a few studies to measure the void fraction of magnetic fluid because several conventional measurement techniques are difficult to apply to a magnetic fluid. In the present study, electromagnetic induction method was installed to measure the vapor void fraction and this measurement technique was proved to be valid for measuring void fraction of vapor bubbles. As a result, the present measurement was able to confirm the reduction of vapor void fraction under the influence of an external magnetic field.
Physical review letters, Jan 27, 2015
In this Letter, we propose a counterintuitive use of a hybrid system where the coherence time of ... more In this Letter, we propose a counterintuitive use of a hybrid system where the coherence time of a quantum system can be significantly improved by coupling it with a system of a shorter coherence time. Coupling a two-level system with a single nitrogen-vacancy (NV^{-}) center, a dark state of the NV^{-} center naturally forms after the hybridization. We show that this dark state becomes robust against noise due to the coupling even when the coherence time of the two-level system is much shorter than that of the NV^{-} center. Our proposal opens a new way to use a quantum hybrid system for the realization of robust quantum information processing.
ABSTRACT A Time-resolved Kerr rotation spectroscopy under selective excitation by narrow spectrum... more ABSTRACT A Time-resolved Kerr rotation spectroscopy under selective excitation by narrow spectrum pump beam is applied to high-mobility two dimensional (2D) electrons. The large non-oscillating Kerr signal is ascribed to the formation of Skyrmions by photoexcited carrier, and is confirmed by the selective excitation in TRKR measurement. The collapse of the spin coherence (dip of T2*) near nu = 1 may be related by the formation of Skyrmions and anti-Skyrmiosn pair under photoexcitation.
ABSTRACT The role of the step in the initial stage of graphene growth is focused on, and recipe h... more ABSTRACT The role of the step in the initial stage of graphene growth is focused on, and recipe how to improve the domain size of the grown graphene is discussed based on the first-principles calculations. It is considered that keeping the surface smoothness and limiting the number of C aggregation sites are the keys to improve the domain size.
Physical review letters, Jan 17, 2014
An electromechanical resonator is developed in which mechanical nonlinearities can be dynamically... more An electromechanical resonator is developed in which mechanical nonlinearities can be dynamically engineered to emulate the nondegenerate parametric down-conversion interaction. In this configuration, phonons are simultaneously generated in pairs in two macroscopic vibration modes, resulting in the amplification of their motion. In parallel, two-mode thermal squeezed states are also created, which exhibit fluctuations below the thermal motion of their constituent modes as well as harboring correlations between the modes that become almost perfect as their amplification is increased. The existence of correlations between two massive phonon ensembles paves the way towards an entangled macroscopic mechanical system at the single phonon level.
Methods in molecular biology (Clifton, N.J.), 2012
Proteolysis is the key step for proteomic studies integrated with MS analysis. Compared with the ... more Proteolysis is the key step for proteomic studies integrated with MS analysis. Compared with the conventional method of in-solution digestion, proteolysis by a protease-immobilized microreactor has a number of advantages for proteomic analysis; i.e., rapid and efficient digestion, elimination of a purification step of the digests prior to MS, and high stability against a chemical or thermal denaturant. This chapter describes the preparation of the protease-immobilized microreactors and proteolysis performance of these microreactors. Immobilization of proteases by the formation of a polymeric membrane consisting solely of protease-proteins on the inner wall of the microchannel is performed. This was realized either by a cross-linking reaction in a laminar flow between lysine residues sufficiently present on the protein surfaces themselves or in the case of acidic proteins by mixing them with poly-lysine prior to the crosslink-reaction. The present procedure is simple and widely usefu...