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Search Results: 1 - 10 of 1050 matches for " Takeo Higuchi "
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Observation of Environmental Stress Cracking in Polymethylmethacrylate by Using the Chemiluminescence Method  [PDF]
Yuji Higuchi
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.611107
Abstract: Polymethylmethacrylate (PMMA) is highly regarded for its transparency, and is used in such products as cameras and Video Tape Recorders as plastic lenses to take advantage of its excellent optical properties. Also, it is used in numerous other industrial fields like automobile lamp lenses, billboards, and lighting equipment. The phenomenon of environmental stress cracking is known to occur in PMMA due to ethanol, and there are cases when this may become a factor which causes damage of molded products. In the present paper, upon close observation by using the method of chemiluminescence in order to elucidate the mechanism by which this environmental stress cracking occurs, we report that we are able to capture the formation of a radical at the moment of cracking.
Readout system with on-board demodulation for CMB polarization experiments using coherent polarimeter arrays
Koji Ishidoshiro,Makoto Nagai,Takeo Higuchi,Masaya Hasegawa,Masashi Hazumi,Masahiro Ikeno,Osamu Tajima,Manobu Tanaka,Tomohisa Uchida
Physics , 2011, DOI: 10.1109/TNS.2012.2195029
Abstract: B-modes are special patterns in cosmic microwave background (CMB) polarization. The detection of them is a smoking-gun signature of primordial gravitational waves. The generic strategy of the CMB polarization experiments is to employ a large number of polarimeters for improving the statistics. The Q/U Imaging ExperimenT-II (QUIET-II) has been proposed to detect the B-modes using the world's largest coherent polarimeter array (2,000 channels). An unique detection technique using QUIET's polarimeters, which is a modula- tion/demodulation scheme, enables us directly extracting the polarization signal. The extracted signal is free from non- polarized components and intrinsic 1/f noise. We developed a data readout system with on-board demodulation functions for the QUIET-II experiment. We employed a "master" clock strategy. This strategy guarantees phase matching between the modulation by the polarimeters and the demodulation by ADC modules. The single master generates all carrier clocks and distributes them to each module. The developed electronics, clock modules, and the ADC modules fulfill requirements. Tests with a setup similar to that of the real experiment proved that the system works properly. The performance of all system components are validated to be suitable for B-mode measurements.
A Scheme for Calculating Atomic Structures beyond the Spherical Approximation  [PDF]
Mitiyasu Miyasita, Katsuhiko Higuchi, Masahiko Higuchi
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.25052
Abstract: We present a scheme for calculating atomic single-particle wave functions and spectra with taking into ac-count the nonspherical effect explicitly. The actual calculation is also performed for the neutral carbon atom within the Hartree-Fock-Slater approximation. As compared with the conventional atomic structure of the spherical approximation, the degenerate energy levels are split partially. The ground state values of the total orbital and spin angular momenta are estimated to be both about unity, which corresponds to the term P3PP in the LS-multiplet theory. This means that the nonspherical effect may play an essential role on the description of the magnetization caused by the orbital polarization.
Self-Consistent Calculations on the Atomic Electron Affinity and Ionization Energy with Taking Effects of the Nonspherical Distribution of Electrons into Account  [PDF]
Mitiyasu Miyasita, Katsuhiko Higuchi, Masahiko Higuchi
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.210144
Abstract: We perform the self-consistent calculations on the atomic electron affinity and ionization energy for the first-row atoms by means of our scheme. A striking feature of the present work is the variational method with taking into account effects of the nonspherical distribution of electrons explicitly. Comparing the present results with those of the conventional spherical approximation, the systematical improvement can be found. This means that effects of the nonspherical distribution of electrons may play an essential role on the description of the atomic structures.
Arbitrary Choice of Basic Variables in Density Functional Theory. II. Illustrative Applications
K. Higuchi,M. Higuchi
Physics , 2003, DOI: 10.1103/PhysRevB.69.165118
Abstract: Our recent theory (Ref. 1) enables us to choose arbitrary quantities as the basic variables of the density functional theory. In this paper we apply it to several cases. In the case where the occupation matrix of localized orbitals is chosen as a basic variable, we can obtain the single-particle equation which is equivalent to that of the LDA+U method. The theory also leads to the Hartree-Fock-Kohn-Sham equation by letting the exchange energy be a basic variable. Furthermore, if the quantity associated with the density of states near the Fermi level is chosen as a basic variable, the resulting single-particle equation includes the additional potential which could mainly modify the energy-band structures near the Fermi level.
$N$-representability of the Jastrow wave function pair density of the lowest-order
Katsuhiko Higuchi,Masahiko Higuchi
Physics , 2008,
Abstract: We have recently proposed a density functional scheme for calculating the ground-state pair density (PD) within the Jastrow wave function PDs of the lowest-order (LO-Jastrow PDs) [M. Higuchi and K. Higuchi, Phys. Rev. A \textbf{75}, 042510 (2007)]. However, there remained an arguable problem on the $N$-representability of the LO-Jastrow PD. In this paper, the sufficient conditions for the $N$-representability of the LO-Jastrow PD are derived. These conditions are used as the constraints on the correlation function of the Jastrow wave function. A concrete procedure to search the suitable correlation function is also presented.
Arbitrary Choice of Basic Variables in Density Functional Theory. I. Formalism
M. Higuchi,K. Higuchi
Physics , 2003, DOI: 10.1103/PhysRevB.69.035113
Abstract: The Hohenberg-Kohn theorem of the density functional theory is extended by modifying the Levy constrained-search formulation. The new theorem allows us to choose arbitrary physical quantities as the basic variables which determine the ground-state properties of the system. Moreover, the theorem establishes a minimum principle with respect to variations in the chosen basic variables as well as with respect to variations in the density. By using this theorem, the self-consistent single-particle equations are derived. N single-particle orbitals introduced reproduce the basic variables. The validity of the theory is confirmed by the examples where the spin-density or paramagnetic current-density is chosen as one of the basic variables. The resulting single-particle equations coincide with the Kohn-Sham equations of the spin-density functional theory (SDFT) or current-density functional theory (CDFT), respectively. By choosing basic variables appropriate to the system, the present theory can describe the ground-state properties more efficiently than the conventional DFT.
Basic variables to be reproduced in the first-principles theory for superconductors: Fluctuation of the particle number
Katsuhiko Higuchi,Masahiko Higuchi
Physics , 2015,
Abstract: We show that the diagonal elements of the second-order reduced density matrix (RDM2) can be chosen as basic variables for describing the superconducting state, instead of the off-diagonal elements of the RDM2 that are usually adopted as basic variables in the density functional scheme. The diagonal elements of the RDM2 are called pair-density (PD), which is explicitly related to the fluctuation of the particle number of the system. In this paper, we argue that the fluctuation of the particle number can become an indication of the superconducting state, and that the density functional scheme in which the PD is chosen as a basic variable would be a promising first-principles theory for superconductors.
Pair density functional theory by means of the correlated wave function
Masahiko Higuchi,Katsuhiko Higuchi
Physics , 2006, DOI: 10.1103/PhysRevA.75.042510
Abstract: We present a density functional scheme for calculating the pair density (PD) by means of the correlated wave function. This scheme is free from both of problems related to PD functional theory, i.e., (a) the need to constrain the variational principle to $N$-representable PDs and (b) the development of a kinetic energy functional. By using the correlated wave function, the searching region for the ground-state PD is substantially extended as compared with our previous theory[Physica B \textbf{372} (2007), in press]. The variational principle results in the simultaneous equations that yield the best PD beyond the previous theory, not to mention the Hartree-Fock approximation.
A correction method for the pair density to get close to the ground state one
Masahiko Higuchi,Katsuhiko Higuchi
Physics , 2011,
Abstract: We present a correction method for the pair density (PD) to get close to the ground state one. The PD is corrected to be a variationally-best PD within the search region that is extended by adding the uniformly-scaled PDs to its elements. The corrected PD is kept N-representable and satisfies the virial relation rigorously. The validity of the present method is confirmed by numerical calculations of neon atom. It is shown that the root-mean-square error of the electron-electron interaction and external potential energies, which is a good benchmark for the error of the PD, is reduced by 69.7% without additional heavy calculations.
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