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Showing papers by "University of Electro-Communications published in 1980"


Book ChapterDOI
01 Jan 1980

97 citations



Journal ArticleDOI
TL;DR: In this article, the temperature dependence of the high-spin content for various iron concentration reproduces the essential features of the observed results including the linear dependence of spin transition temperature on the concentration, and the dilution effect on the highspin\rightleftarrows\)low-spin transition is studied on the basis of the ligand field theory by taking account of the coupling between d electrons of iron and a lattice strain.
Abstract: Sorai et al. (Chem. Phys. 18 (1976) 199) observed that the spin transition temperature in [Fe x Zn 1- x (2-pic) 3 ]Cl 2 ·C 2 H 5 OH varies linearly with iron concentration and the slope of the temperature dependence curve of the high-spin content becomes less steep with decreasing concentration. This dilution effect on the high-spin\(\rightleftarrows\)low-spin transition is studied on the basis of the ligand field theory by taking account of the coupling between d electrons of iron and a lattice strain. The calculated temperature dependence of the high-spin content for various iron concentration reproduces the essential features of the observed results including the linear dependence of the spin transition temperature on the concentration.

44 citations


Journal ArticleDOI
TL;DR: In this article, a detailed study on the thermoelectric power of boron phosphide crystals is carried out at high temperatures ranging from 300 to 1200 K, and the structure and electrical properties also are studied for specimens of various growth temperatures.
Abstract: A detailed study on the thermoelectric power of boron phosphide crystals is carried out at high temperatures ranging from 300 to 1200 K. The structure and the electrical properties also are studied for specimens of various growth temperatures. The thermoelectric power of boron phosphide is found to be −300 to −500 μV/K for n-type and about +500 μV/K for p-type at 500 K. Ionized impurity scattering and lattice defect scattering are considered to be the dominant mechanism to determine thermoelectric power values. The activation energy of ionized impurity is estimated to be (0.02 ± 0.01) eV and that of lattice defect is found to have activation energies of (0.09 ± 0.02) and (0.2 ± 0.02) eV. Ausfuhrliche Untersuchungen der Thermospannung werden fur Borphosphidkristalle im hohen Temperaturbereich von 300 bis 1200 K durchgefuhrt. Zur gleichen Zeit werden die Struktur und die elektrischen Eigenschaften der bei verschiedenen Temperaturen gewachsenen Proben untersucht. Es wird gefunden, das die Thermokraft des Borphosphidkristalls −300 bis −500 μV/K fur n-Leitung und etwa +500 μV/K fur p-Leitung betragt. Die Streuung an ionisierten Fremdatomen und an Gitterstorungen wird als Hauptmechanismus betrachtet, der den Betrag der Thermospannung bestimmt. Es wird auch gefunden, das die Aktivierungsenergie (0,02 ± 0,01) eV fur die Streuung an ionisierten Fremdatomen und (0,09 ± 0,02) und (0,2 ± 0,02) eV fur die Streuung an Gitterstorungen betragt.

23 citations


Journal ArticleDOI
TL;DR: In this article, the electrical properties of polycrystalline boron nitride (BN) films deposited on silicon substrates in a B 2 H 6 NH 3 ǫ 2 system were investigated.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the electronic band structures of ferromagnetic Cd${\mathrm{Cr}}_{2}$${S}}_{4}$ and Cd€{Cr€{S€ 1}€ 2] are self-consistently calculated by using the discrete variational $X\ensuremath{\alpha}$ method.
Abstract: The electronic band structures of ferromagnetic Cd${\mathrm{Cr}}_{2}$${\mathrm{S}}_{4}$ and Cd${\mathrm{Cr}}_{2}$${\mathrm{Se}}_{4}$ are self-consistently calculated by using the discrete variational $X\ensuremath{\alpha}$ method. The general features of the band structures are quite similar between sulfide and selenide; each structure consists of relatively narrow valence bands, fairly wide conduction bands, and very narrow $d$ bands. The $3d\ensuremath{\epsilon}$ and $3d\ensuremath{\gamma}$ bands for up spin lie in the energy region near the top of the valence bands and around the bottom of the lowest conduction band, respectively, and both $d$ bands for down spin fall in the conduction bands. The maximum point of the valence bands has ${\ensuremath{\Sigma}}_{4}$ symmetry for both compounds, and the minimum point of the conduction band has ${\ensuremath{\Lambda}}_{1}$ for sulfide and ${\ensuremath{\Gamma}}_{1}$ for selenide. The fundamental energy gap at the $\ensuremath{\Gamma}$ point is 2.6 eV for sulfide and 2.3 eV for selenide. The spin polarization of the $3d$ orbitals of Cr is about 3.5, in which 0.5 comes from the $3d\ensuremath{\gamma}$ components mixed with the valence bands, while the spin polarization of the outermost $p$ orbitals of chalcogen ion has the opposite sign, the magnitude of which is about 0.3.

18 citations


Journal ArticleDOI
TL;DR: In this article, the electronic band structures of the paramagnetic and ferromagnetic phases of chromium spinels CdCr2S4 and CcCr2Se4 are calculated by the use of the extended Huckel method and assignments of the optical spectra are given.
Abstract: The electronic band structures of the paramagnetic and ferromagnetic phases of chromium spinels CdCr2S4 and CdCr2Se4 are calculated by the use of the extended Huckel method and assignments of the optical spectra are given.

15 citations


Journal ArticleDOI
TL;DR: In this article, the transfer law of reliability curve has been determined to predict the distribution of fatigue life under variable stress amplitudes from that under constant amplitude, where the cumulative cycle ratio Σ n/N is statistically distributed.

8 citations


Journal ArticleDOI
TL;DR: In this article, the electron impact induced fragmentation of 1-benzoylbenzotriazole has been studied by 13C labelling experiments, and it has been found that the loss of CO from the [M N2]-˙ ions proceeds by two routes; about 78% of the ions decompose via the molecular ions of 2-phenylbenzoxazole, and 22% via those of the corresponding photochemical fragmentation product, 6-phenanthridone.
Abstract: The electron impact induced fragmentation of 1-benzoylbenzotriazole has been studied by 13C labelling experiments. It has been found that the loss of CO from the [M N2]+˙ ions proceeds by two routes; about 78% of the ions decompose via the molecular ions of the corresponding thermal fragmentation product, 2-phenylbenzoxazole, and 22% via those of the corresponding photochemical fragmentation product, 6-phenanthridone.

7 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present an experimental result of stress corrosion cracking and propose a statistical approach for time-dependent fracture, which has wide applicability to other timedependent fracture as well.
Abstract: The understanding of statistical aspects of time-dependent fracture is important to assure high structural reliability as well as to elucidate fracture mechanisms. With respect to stress corrosion cracking (SCC), rather few statistical experiments have been reported [i]. The purpose of this note is to present our experimental result and to propose a relevant idea. The idea has wide applicability to other timedependent fracture as well.

6 citations


Journal ArticleDOI
TL;DR: A remarkable feature of this method is that an oxide thickness localized in a very small area is measurable, and the measurement is carried out for an oxide deposided in 0.1-mm-wide ditches.
Abstract: A method for measuring the thickness of a very thin oxide layer by secondary electron emission is described. The secondary electron signals are measured for an oxide-covered silicon surface and a reference surface by using the line mode of scanning electron microscope. Then, their ratio correlates well with the thickness of oxide layer, and it is demonstrated that the thickness of an oxide layer can be obtained by measuring the ratio gamma. At the beam energy of 2 keV, the measurable thickness lies within the range of 15-150 A. The lower limit is due to the natural oxide remaining on the reference-silicon surface and the upper limit to charging effects of oxide layers. A remarkable feature of this method is that an oxide thickness localized in a very small area is measurable, and the measurement is carried out for an oxide deposided in 0.1-mm-wide ditches.

Journal ArticleDOI
TL;DR: From the studies on temperature spectral change of in-beam electron impact spectra it became clear that rapid heating of the sample over the temperature range 200-300 degrees C gave abundant [M + 1]+ ions as well as fragment ions originating from the thermally intact peptide as the major peaks in the spectrum.
Abstract: The characteristics of the in-beam electron impact mass spectra of 13 N-carbobenzoxyoligopeptides (up to pentapeptides) composed mainly of leucine and isoleucine, and their alkyl and N-hydroxysuccinimide esters are described. In the cases of di- and tripeptide derivatives, each in-beam electron impact spectrum exhibited an abundant [M + 1]+ peak as well as amino-acyl fragments. However, in the case of pentapeptides the in-beam spectra measured under the routine conditions corresponded to the conventional electron impact spectra of the cyclopeptide derivatives formed by thermal cyclization in the mass spectrometer and few [M + 1]+ ions of the original peptides were observed. From the studies on temperature spectral change of in-beam electron impact spectra it became clear that rapid heating of the sample over the temperature range 200-300 degrees C gave abundant [M + 1]+ ions as well as fragment ions originating from the thermally intact peptide as the major peaks in the spectrum.


Journal ArticleDOI
TL;DR: In this article, the characteristics of allowed and forbidden transitions of Eu2+ ions in CaF2 single crystals have been investigated at room temperature, and the angular dependences of these transition intensities were theoretically calculated with the use of perturbation theory, and compared with the experimental values.


Journal ArticleDOI
TL;DR: In this paper, the cold-plasma model of the radio wave scattering from spatially random fluctuations of electron density in an anisotropic plasma is extended to the warm-plasmas model, in which the effect of electron pressure is taken into account.
Abstract: The cold-plasma model of the radio wave scattering from spatially random fluctuations of electron density in an anisotropic plasma is extended to the warmplasma model, in which the effect of electron pressure is taken into account. Since the medium is compressible as well as anisotropic, there is the additional possibility of mode conversion from an incident electromagnetic wave to a scattered electron plasma wave. Some numerical results are also included.

Book ChapterDOI
TL;DR: The orthonormality-constrained variation (ONCV) method as mentioned in this paper is a variational approach for kvectors with the orthonormal constraint, which was introduced by Lowdin's method.
Abstract: Publisher Summary This chapter provides a general description of a new variational approach for ketvectors with the orthonormality constraint named orthonormality-constrained variation, (ONCV), a method of characterization of eigenvalues by use of ONCV, comments on the stability of solutions, and derivation of SCF equations with comparison to the usual Lagrange multipliers method, clarifying significance of some unrevealed aspects of Lowdin's orthonormalization method. Lowdin first explained the cohesive and elastic properties of alkali halide crystals by using the orthogonalized wave functions. The nonorthogonality problem in molecular orbital theory of atoms and molecules was studied by Pauling, Slater and others, who developed the so-called maximum overlapping principle from the consideration that the strength of a chemical bond should be measured by the degree of the overlap between the orbitals involved. Pauling's hybrid orbitals are constructed from an atomic orbital set so as to satisfy, first, the normalization, second, the orthogonality, and third, an implicit condition that hybrid orbitals can be spanned completely by a set of atomic orbitals. In addition, the chapter also describes a relation of the ONCV method to the Edmiston–Ruedenberg localized orbital method and also expands the ONCV method to a pair of ket-vector sets and proposes a method for constraining pairorthogonality- orthogonality between two basis sets-in the course of variation.

Journal ArticleDOI
TL;DR: In this paper, it was shown that if B0 is prediction sufficient (adequate) for B with respect to C and P, then B0vC is sufficient for B0 vC vBvC vC with respect (B0, C, B0, B1, B2, B3, B4, B5, B6, B7, B8, B9, B10, B11, B12, B13, B14, B15, B16, B17, B19, B20, B21
Abstract: Summary Let(X, A) be a measurable space and P a family of probability measures on A. Let B and C be sub s-algebras of A and B0 a sub s-algebra of B. It is shown that if B0 is prediction sufficient (adequate) for B with respect to C and P, and Y is sufficient for B0vC with respect to P then Y is sufficient for BvC with respect to P; that if P is homogeneous and (B0; B, C) is Markov for P, and B0vC is sufficient for Bvc with respect to P, then B0 is sufficient for B with respect to P; and by example that the Markov property is necessary for the latter proposition to hold.

Journal ArticleDOI
TL;DR: In this paper, a new nomographic diagram for the design and analysis of paraxial systems has been proposed, which has proved to have the following advantages: (i) Paraxial ray tracing can be performed graphically, with the result being represented by a pattern on the diagram; (ii) from the given pattern of an arbitrary ray, all the structural parameters of the system, and paths of any other rays can be obtained on the diagrams; and (iii) the nomographic scales devised specially for the diagram facilitate direct reading and/or plotting of the parasilae parameters
Abstract: A new nomographic diagram for design and analysis of paraxial systems has been proposed. The diagram has proved to have the following advantages: (i) Paraxial ray tracing can be performed graphically, with the result being represented by a pattern on the diagram; (ii) from the given pattern of an arbitrary ray, all the structural parameters of the system, and paths of any other rays can be obtained on the diagram; (iii) the nomographic scales devised specially for the diagram facilitate direct reading and/or plotting of the paraxial parameters, e.g., focal lengths, positions of pupils and cardinal points; and, (iv) a system with unknown structural parameters can also be treated on the diagram, provided the entrance and exit conditions are given for a pair of independent rays. It has been shown that the y-ӯ diagram can be obtained from the proposed diagram by a simple graphical transformation.

Journal ArticleDOI
TL;DR: In this paper, an optical tachometer is developed by the analog processing of the signals obtained from the silicon solar cell displacement sensors, and a satisfactorily smooth acceleration signal is obtained by simple filtering.
Abstract: An optical tachometer is developed by the analog processing of the signals obtained from the silicon solar cell displacement sensors. Differentiating the speed signal, satisfactorily smooth acceleration signal is obtained by simple filtering. The torque-speed curve plotting for small motors by the application of this technique and the effects of the filtering on the plot are described.

Book ChapterDOI
01 Oct 1980
TL;DR: Analysis of analytically solvable queueing models of multiprogramming with different jobs and various scheduling disciplines shows that the analysis of these models supports the optimality of the already proposed CPU scheduling discipline which assigns higher processing priority to a more I/O bound job.
Abstract: Several analytically solvable queueing models of multiprogramming with different jobs and various scheduling disciplines are investigated. It is shown that the analysis of these models supports the optimality of the already proposed CPU scheduling discipline which assigns higher processing priority to a more I/O bound job. Furthermore, the effects of some endogenous scheduling disciplines such as preemptive-resume last-come-first-served are compared with that of this discipline using some queueing models.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the cable in which two inner conductors are very close and obtained the solution of such a shielded cable pair by quasi-TEM mode approximation, using the method of conformal mapping.
Abstract: The shielded cable with close inner conductors is different from the conventional local cable and can be applied to directional couplers. In this paper, for the purpose of obtaining tight coupling, we investigated the cable in which two inner conductors are very close. In particular, we consider the finishing with very fine conductors for small power application. In this case, it is necessary to use a second dielectric in order to maintain the space between the inner conductors, resulting in an inhomogeneous media. For the solution of such a shielded cable pair by quasi-TEM mode approximation, we use the method of conformal mapping. Also, the measurements of the cable constants and the restrictions of a directional coupler by TEM approximation are described. The approximate equations obtained are applicable to the design of a cable with tight coupling below about 10 dB and the trial production of 3 dB- and 5 dB-cables was proved to be satisfactory. The directional couplers using these cables are possible in practice and we expect to see their application in the VHF and UHF bands.

Journal ArticleDOI
TL;DR: In this article, the spectra of frequency shifts of the Doppler echoes from the F-region ionosphere over central Japan were used to study the power spectrum densities and revealed that the small-scale fluctuations of the doppler signals contain several dominant periods in the range of 4 to 98min.
Abstract: From the beginning of 1976 the standard type CW Doppler sounder at Sugadaira has been used to study the spectra of frequency shifts of the Doppler echoes from the F-region ionosphere over central Japan. Some of the obtained data samples, with interpolated sections, are subjected to maximum entropy spectral analysis. The resultant power spectrum densities have revealed that the small-scale fluctuations of the Doppler signals contain several dominant periods in the range of 4 to 98min.


Journal Article
TL;DR: In this paper, the spectra of frequency shifts of the Doppler echoes from the F-region ionosphere over central Japan were used to study the power spectrum densities and revealed that the small-scale fluctuations of the doppler signals contain several dominant periods in the range of 4 to 98min.
Abstract: From the beginning of 1976 the standard type CW Doppler sounder at Sugadaira has been used to study the spectra of frequency shifts of the Doppler echoes from the F-region ionosphere over central Japan. Some of the obtained data samples, with interpolated sections, are subjected to maximum entropy spectral analysis. The resultant power spectrum densities have revealed that the small-scale fluctuations of the Doppler signals contain several dominant periods in the range of 4 to 98min.

Journal ArticleDOI
TL;DR: In this paper, the authors report an approximate method for evaluating resistances using two kinds of resistive media, and propose a design method for composite thin-film resistance and three-port attenuator based on the analysis result and conformal mapping.
Abstract: In designing the planar resistor and attenuator using uniform resistive media, if the electrode and structural dimension ratio are extremely small or large, the design is not realizable. In such cases, the realizable design range can be enlarged by using two kinds of resistive media. However, the resistance value can be obtained by solving nonuniform boundary value problems. In this paper, we report an approximate method for evaluating resistances using two kinds of resistive media. Further, the design method for composite thin-film resistance and three-port attenuator is proposed based on the analysis result and conformal mapping. The result of the analysis agrees with the experiment within the practical accuracy.


Journal ArticleDOI
TL;DR: In this article, the pair effects among bonds are included in the CPA treatment of the bond model of disordered Heisenberg ferromagnet, where all spins are equated to 1 2 but two distinct exchange integrals are distributed randomly among bonds.

Book ChapterDOI
24 Oct 1980
TL;DR: This paper investigates problems which require O(nk) time, for each interger k, where n is the size of input and presents a number of problems which requires exponential time.
Abstract: In this paper, we investigate problems which require O(nk) time, for each interger k, where n is the size of input. Also, we present a number of problems which require exponential time.