Search results for: Kazuhide Ichikawa

Items from 1 to 20 out of 26 results

chapter

Tunable terahertz bandpass filter using MEMS reconfigurable metamaterial

Kazuhide Ichikawa, Zhengli Han, Hiroshi Toshiyoshi

2017 International Conference on Optical MEMS and Nanophotonics (OMN) > 1 - 2

2017 International Conference on Optical MEMS and Nanophotonics (OMN)

We report on a tunable terahertz bandpass filter based on a cross-shaped slot resonator with a reconfigurable roll-up micro structures. The built-in capacitors within the resonator are electrostatically actuated to shift the resonant frequency.

article

Singular Unit Restoration in InSAR Using Complex-Valued Neural Networks in the Spectral Domain

Kazuhide Ichikawa, Akira Hirose

IEEE Transactions on Geoscience and Remote Sensing > 2017 > 55 > 3 > 1717 - 1723

Interferograms obtained by interferometric synthetic aperture radar generally include many singular points (SPs) originating from interference distortion and noise in the measurement. The filtering process is one of the key techniques in the generation of an accurate digital elevation model (DEM). In this paper, we propose a filter to remove SPs and related distortion using a complex-valued neural...

chapter

Proposal of singular-point-removing filters with strong nonlinearity in spectral domain

Kazuhide Ichikawa, Akira Hirose

2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) > 3201 - 3204

IGARSS 2016 - 2016 IEEE International Geoscience and Remote Sensing Symposium

Filtering process plays significant roles in the generation of a digital elevation model (DEM) from interferogram obtained by interferometric synthetic aperture radar (InSAR). In order to remove the distortion of a so-called singular unit (SU), this paper proposes two novel filtering techniques which both exhibit strong nonlinearity. The first method attempts to remove the distortion by focusing on...

article

Theoretical study of lithium ionic conductors by electronic stress tensor density and electronic kinetic energy density

Hiroo Nozaki, Yosuke Fujii, Kazuhide Ichikawa, Taku Watanabe, more

Journal of Computational Chemistry > 37 > 20 > 1924 - 1934

We analyze the electronic structure of lithium ionic conductors,

{Li}_{3} {PO}_{4}

and

{Li}_{3} {PS}_{4}

, using the electronic stress tensor density and kinetic energy density with special focus on the ionic bonds among them. We find that, as long as we examine the pattern of the eigenvalues of the electronic stress tensor density, we cannot distinguish between the ionic bonds and bonds among metalloid atoms. We then...

article

Computational method for the retarded potential in the real‐time simulation of quantum electrodynamics

Masahiro Fukuda, Kento Naito, Kazuhide Ichikawa, Akitomo Tachibana

International Journal of Quantum Chemistry > 116 > 12 > 932 - 938

We discuss the method to compute the integrals, which appear in the retarded potential term for a real‐time simulation based on quantum electrodynamics. We show that the oscillatory integrals over the infinite interval involved in them can be efficiently performed by the method developed by Ooura and Mori based on the double exponential formula. © 2016 Wiley Periodicals, Inc.

article

Bonding in doped gallium nanoclusters: Insights from regional DFT

David J. Henry, Kazuhide Ichikawa, Hiroo Nozaki, Akitomo Tachibana

Computational Materials Science > 2016 > 115 > C > 145-153

The molecular nature (Ga₂)_n of gallium makes this an interesting metal to investigate for the development of novel nano-materials. However, establishment of a targeted approach to manipulating the properties of gallium clusters requires a detailed understanding of how doping affects the bonding in these species. In this study, the bonding of gallium nanoclusters has been investigated using electron...

article

Theoretical study of atoms by the electronic kinetic energy density and stress tensor density

Hiroo Nozaki, Kazuhide Ichikawa, Akitomo Tachibana

International Journal of Quantum Chemistry > 116 > 7 > 504 - 514

The electronic structure of atoms in the first, second, and third periods were analyzed using the electronic kinetic energy density and stress tensor density, which are local quantities motivated by quantum field theoretic consideration, specifically the rigged quantum electrodynamics. The zero surfaces of the electronic kinetic energy density, which are called as the electronic interfaces, of the...

article

Electronic stress tensor analysis of molecules in gas phase of CVD process for gesbte alloy

Hiroo Nozaki, Yuji Ikeda, Kazuhide Ichikawa, Akitomo Tachibana

Journal of Computational Chemistry > 36 > 16 > 1240 - 1251

We analyze the electronic structure of molecules which may exist in gas phase of chemical vapor deposition process for GeSbTe alloy using the electronic stress tensor, with special focus on the chemical bonds between Ge, Sb, and Te atoms. We find that, from the viewpoint of the electronic stress tensor, they have intermediate properties between alkali metals and hydrocarbon molecules. We also study...

article

Study of simulation method of time evolution of atomic and molecular systems by quantum electrodynamics

Kazuhide Ichikawa, Masahiro Fukuda, Akitomo Tachibana

International Journal of Quantum Chemistry > 114 > 23 > 1567 - 1580

We discuss a method to follow step‐by‐step time evolution of atomic and molecular systems based on quantum electrodynamics. Our strategy includes expanding the electron field operator by localized wavepackets to define creation and annihilation operators and following the time evolution using the equations of motion of the field operator in the Heisenberg picture. We first derive a time evolution...

article

Ventricular Function and Dyssynchrony Quantified by Speckle-Tracking Echocardiography in Patients with Acute and Chronic Right Ventricular Pressure Overload

Kazuhide Ichikawa, Kaoru Dohi, Emiyo Sugiura, Tadafumi Sugimoto, more

Journal of the American Society of Echocardiography > 2013 > 26 > 5 > 483-492

The aim of this study was to noninvasively investigate right ventricular and left ventricular (LV) adaptation to right ventricular pressure overload in patients with acute pulmonary thromboembolism (APTE) and chronic pulmonary artery hypertension (CPAH).Thirty-seven patients with APTE, 36 patients with CPAH, and 33 controls were retrospectively enrolled. Myocardial deformation and wall motion were...

article

Study of simulation method of time evolution in rigged QED

Kazuhide Ichikawa, Masahiro Fukuda, Akitomo Tachibana

International Journal of Quantum Chemistry > 113 > 3 > 190 - 202

We discuss how we formulate time evolution of physical quantities in the framework of the Rigged quantum electrodynamics (QED). The Rigged QED is a theory which has been proposed to treat dynamics of electrons, photons, and atomic nuclei in atomic and molecular systems in a quantum field theoretic way. To solve the dynamics in the Rigged QED, we need different techniques from those developed for the...

article

Short-term effects of low-dose tolvaptan on hemodynamic parameters in patients with chronic heart failure

Kiyotaka Watanabe, Kaoru Dohi, Tadafumi Sugimoto, Tomomi Yamada, more

Journal of Cardiology > 2012 > 60 > 6 > 462-469

We evaluated the short-term effects of low-dose tolvaptan treatment on hemodynamic parameters in patients with chronic heart failure (HF).We studied 22 patients (69±10 years) with chronic HF and excess fluid retention despite receiving appropriate medical therapy, including loop and/or thiazide diuretics. The therapeutic effects of low-dose (7.5mg) once-daily tolvaptan on hemodynamics associated with...

article

Right and Left Ventricular Function, Dyssynchrony, and Interdependence in Patients with Acute and Chronic Pulmonary Artery Hypertension

Kaoru Dohi, Kazuhide Ichikawa, Emiyo Sugiura, Takeshi Takamura, more

Journal of Cardiac Failure > 2012 > 18 > 10 Supplement > S131

article

Theoretical study of hydrogenated tetrahedral aluminum clusters

Kazuhide Ichikawa, Yuji Ikeda, Ayumu Wagatsuma, Kouhei Watanabe, more

International Journal of Quantum Chemistry > 111 > 14 > 3548 - 3555

We report on the structures of aluminum hydrides derived from a tetrahedral aluminum (Al₄) cluster using ab initio quantum chemical calculation. Our calculation of binding energies of the aluminum hydrides reveals that stability of these hydrides increases as more hydrogen atoms are adsorbed, while stability of Al – H bonds decreases. We also analyze and discuss the chemical bonds of those clusters...

article

Reversible Left Ventricular Regional Non-Uniformity Quantified by Speckle-Tracking Displacement and Strain Imaging in Patients with Acute Pulmonary Embolism

Takeshi Takamura, Kaoru Dohi, Katsuya Onishi, Yuko Sakurai, more

Journal of the American Society of Echocardiography > 2011 > 24 > 7 > 792-802

The aim of this study was to investigate the impact of acute right ventricular pressure overload (RVPO) on left ventricular (LV) function and regional uniformity using speckle-tracking displacement and strain analyses in patients with acute pulmonary embolism (PE).Twenty-five patients with acute PE (mean age, 59 ± 16 years) and 25 normal subjects were enrolled. Radial, longitudinal, and circumferential...

article

Reactivity and Regioselectivity of Aluminum Nanoclusters: Insights from Regional Density Functional Theory

David J. Henry, Paweł Szarek, Kosuke Hirai, Kazuhide Ichikawa, more

The Journal of Physical Chemistry C > 2011 > 115 > 5 > 1714 - 1723

article

Electronic stress tensor analysis of hydrogenated palladium clusters

Kazuhide Ichikawa, Ayumu Wagatsuma, Paweł Szarek, Chenggang Zhou, more

Theoretical Chemistry Accounts > 2011 > 130 > 2-3 > 531-542

We study the chemical bonds of small palladium clusters Pd_n (n = 2−9) saturated by hydrogen atoms using electronic stress tensor. Our calculation includes bond orders which are recently proposed based on the stress tensor. It is shown that our bond orders can classify the different types of chemical bonds in those clusters. In particular, we discuss Pd–H bonds associated with the H atoms with high...

article

Inverted-sandwich-type and open-lantern-type dinuclear transition metal complexes: theoretical study of chemical bonds by electronic stress tensor

Kazuhide Ichikawa, Ayumu Wagatsuma, Yusaku I. Kurokawa, Shigeyoshi Sakaki, more

Theoretical Chemistry Accounts > 2011 > 130 > 2-3 > 237-250

We study the electronic structure of two types of transition metal complexes, the inverted-sandwich-type and open-lantern-type, by the electronic stress tensor. In particular, the bond order $$b_\varepsilon$$ measured by the energy density which is defined from the electronic stress tensor is studied and compared with the conventional MO-based bond order. We also examine the patterns found in...

article

Incremental Values of Intact Parathyroid Hormone With Brain Natriuretic Peptide in Assessing Hemodynamic Status of Patients With Heart Failure

Tadafumi Sugimoto, Kaoru Dohi, Katsuya Onishi, Kazuhide Ichikawa, more

Journal of Cardiac Failure > 2010 > 16 > 9 Supplement > S148

article

Measuring the history of cosmic reionization using the 21‐cm probability distribution function from simulations

Kazuhide Ichikawa, Rennan Barkana, Ilian T. Iliev, Garrelt Mellema, more

Monthly Notices of the Royal Astronomical Society > 406 > 4 > 2521 - 2532

The 21‐cm probability distribution function (PDF; i.e. distribution of pixel brightness temperatures) is expected to be highly non‐Gaussian during reionization and to provide important information on the distribution of density and ionization. We measure the 21‐cm PDF as a function of redshift in a large simulation of cosmic reionization and propose a simple empirical fit. Guided by the simulated...

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Keywords

THEORY OF CHEMICAL BOND (6)
WAVE FUNCTION ANALYSIS (6)
STRESS TENSOR (5)
ECHOCARDIOGRAPHY (3)
DISTORTION (2)
KINETIC ENERGY DENSITY (2)
NEURAL NETWORKS (2)
NEURONS (2)
QUANTUM ELECTRODYNAMICS (2)
STRESS TENSOR DENSITY (2)
THEORY OF QUANTIZED FIELDS (2)
ACUTE PULMONARY EMBOLISM (1)
ACUTE PULMONARY THROMBOEMBOLISM (1)
ATOMS (1)
BAND-PASS FILTERS (1)
BARYON DENSITY (1)
BIG BANG NUCLEOSYNTHESIS (1)
BORON TRICHLORIDE (1)
CAPACITORS (1)
CHRONIC PULMONARY ARTERY HYPERTENSION (1)
CMBR (1)
COMPLEX VALUED NEURAL NETWORK (1)
COMPLEX-VALUED NEURAL NETWORK (CVNN) (1)
CONTRACTION (1)
CORE‐VALENCE PARTITIONING (1)
CORRELATION (1)
COSMOLOGY: THEORY (1)
COUPLING (1)
COVALENT BONDING (1)
CROSS-SHAPED SLOT (1)
DE FORMULA (1)
DIGITAL ELEVATION MODEL (DEM) (1)
DIGITAL ELEVATION MODELS (1)
DISPLACEMENT (1)
DIURESIS (1)
DYSSYNCHRONY (1)
ELECTROMAGNETIC SCATTERING (1)
FAST FOURIER TRANSFORM (1)
FILTERING THEORY (1)
FORCE CONSTANT (1)
FREQUENCY-DOMAIN ANALYSIS (1)
GA2 SUB-UNITS (1)
GALAXIES: FORMATION (1)
GALAXIES: HIGH‐REDSHIFT (1)
GALLIUM CLUSTERS (1)
GESBTE (1)
GOLD (1)
HEART FAILURE (1)
HEMODYNAMICS (1)
HYDROGEN MOLECULAR ION (1)
HYDROGENATED ALUMINUM CLUSTER (1)
HYDROGENATED PD CLUSTERS (1)
IMAGE RESTORATION (1)
INTERACTION ENERGY DENSITY (1)
INTERFEROMETRIC SYNTHETIC APERTURE RADAR (INSAR) (1)
IRON(III) HYDROXIDE (1)
LEFT VENTRICLE (1)
LEFT VENTRICULAR FUNCTION (1)
LEPTON ASYMMETRY (1)
LITHIUM IONIC CONDUCTOR (1)
METALLIC BONDING (1)
METAMATERIALS (1)
MICROMECHANICAL DEVICES (1)
NONPERTURBATIVE TECHNIQUES IN FIELD THEORY (1)
NONPERTURBATIVE TECHNIQUES IN FIELDTHEORY (1)
NONPERTURBATIVE TECHNIQUES IN QUANTUM FIELD THEORY (1)
PHASE SINGULAR POINT (SP) (1)
Q-BALLS (1)
QUANTUME LECTRO‐DYNAMICS (1)
REAL‐TIME SIMULATION OF QUANTUM FIELD THEORY (1)
REGIONAL DFT (1)
RELATIVISTIC AND QUANTUM ELECTRODYNAMIC SIMULATION OF ATOMS (1)
RELATIVISTIC AND QUANTUM ELECTRODYNAMICSIMULATIONS OF ATOMS (1)
RELAXATION (1)
RESONANT FREQUENCY (1)
RETARDED POTENTIAL (1)
SEMI-METAL (1)
SEMICONDUCTOR GAS (1)
SINGULAR POINT (1)
SPECTRAL ANALYSIS (1)
SYNTHETIC APERTURE RADAR (1)
TENSION DENSITY (1)
TERAHERTZ METAMATERIAL (1)
TIME DEPENDENT SIMULATIONS OF FIELD THEORY (1)
TIME‐DEPENDENT SIMULATION OF FIELD THEORY (1)
TRANSITION METAL COMPLEXES (1)
TUNABLE BANDPASS FILTER (1)
VASOPRESSIN V2-RECEPTOR ANTAGONIST (1)
VENTRICULAR INTERDEPENDENCE (1)
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Elsevier (12)
Wiley (8)
ieee (3)
Springer (2)
ACS (1)

INFONA - science communication portal

Search results for: Kazuhide Ichikawa

Tunable terahertz bandpass filter using MEMS reconfigurable metamaterial

Singular Unit Restoration in InSAR Using Complex-Valued Neural Networks in the Spectral Domain

Proposal of singular-point-removing filters with strong nonlinearity in spectral domain

Theoretical study of lithium ionic conductors by electronic stress tensor density and electronic kinetic energy density

Computational method for the retarded potential in the real‐time simulation of quantum electrodynamics

Bonding in doped gallium nanoclusters: Insights from regional DFT

Theoretical study of atoms by the electronic kinetic energy density and stress tensor density

Electronic stress tensor analysis of molecules in gas phase of CVD process for gesbte alloy

Study of simulation method of time evolution of atomic and molecular systems by quantum electrodynamics

Ventricular Function and Dyssynchrony Quantified by Speckle-Tracking Echocardiography in Patients with Acute and Chronic Right Ventricular Pressure Overload

Study of simulation method of time evolution in rigged QED

Short-term effects of low-dose tolvaptan on hemodynamic parameters in patients with chronic heart failure

Right and Left Ventricular Function, Dyssynchrony, and Interdependence in Patients with Acute and Chronic Pulmonary Artery Hypertension

Theoretical study of hydrogenated tetrahedral aluminum clusters

Reversible Left Ventricular Regional Non-Uniformity Quantified by Speckle-Tracking Displacement and Strain Imaging in Patients with Acute Pulmonary Embolism

Reactivity and Regioselectivity of Aluminum Nanoclusters: Insights from Regional Density Functional Theory

Electronic stress tensor analysis of hydrogenated palladium clusters

Inverted-sandwich-type and open-lantern-type dinuclear transition metal complexes: theoretical study of chemical bonds by electronic stress tensor

Incremental Values of Intact Parathyroid Hormone With Brain Natriuretic Peptide in Assessing Hemodynamic Status of Patients With Heart Failure

Measuring the history of cosmic reionization using the 21‐cm probability distribution function from simulations

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