Showing papers by "University of Electro-Communications published in 1979"

Finite-field calculations of molecular polarizabilities using field-induced polarization functions: second- and third-order perturbation correlation corrections to the coupled Hartree-Fock polarizability of H2O

Abstract: Ordinary Rayleigh-Schrodinger perturbation theory with Moller-Plesset (RSMP) partitioning is used to calculate second- and third-order correlation corrections to the CHF polarizability and dipole moment of the water molecule by a finite-field procedure. [2/1] Pade approximants are found to be useful in accelerating the convergence of the property perturbation expansions. Field-induced polarization functions suitable for polarizability calculations are determined. The average polarizability calculated, neglecting vibrational averaging, with Dunning's (9s5p/4s-4s2p/2s) contracted GTO basis set augmented by field-induced 1s1p2d/1p polarization functions is within 3 per cent of the experimental result. Correlation corrections to the dipole moment and polarizability of the water molecule calculated by the finite-field RSMP and single + double excitation CI(SDCI) methods for the same basis set are found to be in close agreement. The RSMP approach has the advantages of being size-consistent and of being capable ...

An Approximate Dispersion Formula of Microstrip Lines for Computer-Aided Design of Microwave Integrated Circuits

Abstract: A simple approximate formula for the computer-aided design of the dispersion property of microstrip lines is reported in this paper which well fits the calculated curves based on a rigorous analysis.

Oxygen Induced Photoconductivity in Lead Phthalocyanine

Abstract: Photoconductive properties (photoresponse, dependences of photocurrent on temperature and light intensity, etc.) of lead phthalocyanine single crystal doped with various levels of oxygen were measured and the role of oxygen in the generation and the recombination of photocarriers was studied. Experimental results are explained on the model that a hole-like carrier is indirectly photo-generated via the charge transfer state at an oxygen center and recombines with the ionized oxygen.

Analysis of Raman Spectra of the Overdamped Mode in KH2(1-x)D2xPO4 Crystals with Single-Mode Line Shape Functions

Abstract: The Raman spectra of an overdamped B 2 -mode in KH 2(1- x ) D 2 x PO 4 crystals have been analyzed with the generalized form of single-mode susceptibility. It has been shown that the absolute value of a pole \( \tilde{\omega}_{1}\) of χ(ω) which makes a larger contribution to the line shape, e.g., in case of a damped harmonic oscillator, a pole closest to the origin, is the most appropriate parameter to describe the phase transition regardless of the model adopted in the analysis. The |ω 1 | was proved to have a linear temperature dependence for any x in the neighborhood of T c . It is suggested that there exists a critical degree of deuteration \(x_{\text{c}} \cong 0.2\), at which the mechanism of the phase transition changes qualitatively.

A refined analysis of drift flow of hydrogen to a crack tip

Abstract: Diffusion of hydrogen to a crack tip is a fundamental process in hydrogen assisted cracking. In the initial stage of diffusion, the stress gradient is more effective than the concentration gradient, and thus, the drift flow is dominant. According to the analysis of the drift flow of solute atoms to a crack tip by lino [l], the number of hydrogen atoms n(t) which arrive at a mode I crack tip within a time t in a state of plane strain (per unit length of the crack front) is given by where Po is the initial uniform concentration in terms of the number of hydrogen atoms per unit volume, ~ Poisson's ratio, v H the partial atomic volume of hydrogen in the solid, D the diffusion coefficient, K I the mode I stress intensity factor; k and T have usual meanings. Eq. (i) is useful within a certain limit of t. In order to determine this limit quantitatively, it is necessary to evaluate (i) the influence of terms other than the singular term O//r term) of the stress field, as well as (ii) the influence of the concentration gradient. Consideration of the influence (i) is needed since only the singular term of the stress field has been taken into account in deriving (i). The purpose of this report is to calculate n(t) using the complete expression of the stress field and to evaluate the influence (i). The influence (ii) will be evaluated separately. Consider an infinite solid containing uniformly distributed hydrogen and an elastic crack of length 2a at y = 0, }x] ~ a. At time t = 0, tensile stress a is applied at infinity in the y direction, and hydrogen atoms begin to move to the crack tips. Neglecting the concentration gradient, the flow velocity V is given by V = -(D/kT) grad E, where E is the elastic interaction energy between a hydrogen atom and the stress field. Using the complete expression of the stress field of the crack [2] instead of only the singular term, we get i

Derivation and Characteristics of a Generalized Form of Susceptibility Used in the Analysis of Raman Line Shape for an Overdamped Mode

Abstract: On the basis of Onsager's phenomenological equation of motion, the generalized form of susceptibility is derived. This includes the damped harmonic oscillator (DHO), Van Vleck-Weisskopf and Frohlich susceptibility (VWF) and Debye relaxational model as different limiting cases, and is equivalent to that obtained from the Bloch equation for the Ising model in a transverse field which are used in the pseudo-spin model for KDP-type crystals. Characteristics and mutual relations of susceptibilities are discussed with an emphasis on the difference between DHO and VWF. For a heavily damped mode, DHO becomes difficult to physically interpret since the eigenfrequency and the damping factor may lose their original meaning. In such cases, the only important parameter is the distance from the origin to the pole of χ(ω) in the complex ω-plane.

EPR Study of Ni 2+ -Vacancy Dipoles in LiCl Crystals

Abstract: The paramagnetic resonance spectra of Ni 2+ in LiCl have been studied at 9 GHz. Two kinds of Ni 2+ centers associated with positive ion vacancy in their nearest or next nearest neighbour position are observed. Their spin Hamiltonian parameters are determined to be g x =2.27±0.04, g y =2.26±0.02, g z =2.31±0.01, | D |=0.564±0.002 cm -1 , | E |=0.080±0.002 cm -1 , and g // =2.360±0.005, g ⊥ =2.30±0.05, | D |=3.1±0.3 cm -1 and | E |≃0.0 cm -1 . The Ni 2+ -vacancy dipoles aggregated to form clusters and the isolated dipoles decayed in number. The decay constant of third order rate process is about 1.2×10 5 h -1 (mole fraction) -2 at room temperature. The EPR line width depends upon the crystal orientation. Interaction between near neighbour dipoles contributed to this anisotropic line width.

Asymptotic optimality of the generalized Bayes estimator in multiparameter cases

Abstract: The higher order asymptotic efficiency of the generalized Bayes estimator is discussed in multiparameter cases For all symmetric loss functions, the generalized Bayes estimator is second order asymptotically efficient in the classA 2 of the all second order asymptotically median unbiased (AMU) estimators and third order asymptotically efficient in the restricted classD of estimators

Discretized likelihood methods—asymptotic properties of discretized likelihood estimators (DLE's)

Abstract: Suppose thatX1,X2, ...,X n , ... is a sequence of i.i.d. random variables with a densityf(x, θ). Letc n be a maximum order of consistency. We consider a solution $$\hat \theta _n $$ of the discretized likelihood equation $$\sum\limits_{i = 1}^n {\log f(X_i ,\hat \theta _n + rc_n^{ - 1} ) - } \sum\limits_{i = 1}^n {\log f(X_i ,\hat \theta _n ) = a_n (\hat \theta _n ,r)} $$ wherea n (θ,r) is chosen so that $$\hat \theta _n $$ is asymptotically median unbiased (AMU). Then the solution $$\hat \theta _n $$ is called a discretized likelihood estimator (DLE). In this paper it is shown in comparison with DLE that a maximum likelihood estimator (MLE) is second order asymptotically efficient but not third order asymptotically efficient in the regular case. Further it is seen that the asymptotic efficiency (including higher order cases) may be systematically discussed by the discretized likelihood methods.

Analog Sensing of Displacement Using Silicon Solar Cell

Abstract: A silicon solar cell is used for an optical sensing of displacement in an analog form The sensor consists of a set of lamp and cell with a lamp-control circuit, where a shutter interrupts the light beam The principle of operation, linearity, temperature effect, frequency response, and associated circuit design are described Experimental results on the characteristics of the cell and the sensing circuit are presented A linearity of ±05 percent and a temperature coefficient of 90 ppm/°C are obtained on the simple set An application to a pressure gauge is also given

Effective utilization of off-diagonal hypervirial relations considering diagonal hypervirial relation: harmonic oscillator case

Abstract: The effective utilization of hypervirial relations is scrutinized to improve the approximate excited-state functions in the harmonic oscillator system. A new method is presented which simultaneously employs the off-diagonal hypervirial relations with the diagonal hypervirial relation. In order to use these relations effectively, the following points are pointed out: (i) the presented method is useful to get better reasonable results for the excitation energies and the state functions; (ii) the ground state given must satisfy the virial theorem; (iii) in the hypervirial operator used here as xm, the smaller integers of m's present better results; and (iv) the employment of the comparatively small number of trial basis functions of the type exp (−γ|x|) is sufficient for reproducing the exact excited state. Especially among them, condition (ii) plays an important role. Applying all the proposals to the first and the second excited states, one gets a highly improved excitation energy, state function, and other physical quantities (e.g., transition moment and oscillator strength). The presented method is also found to be more effective than the employment of only the off-diagonal hypervirial relations or the method of the scaling operation. L'utilisation effective des relations hypervirielles a ete examinee en detail pour ameliorer les approximations des fonctions d'onde representant des etats excites pour l'oscillateur harmonique. Une nouvelle methode est presentee, qui utilise simultanement les relations hypervirielles nondiagonales et la relation diagonale. Afin d'employer plus effectivement ces relations les aspects suivants sont mis en evidence: (i) la methode presentee est utile pour obtenier de meilleurs resultats raisonnables pour les energies d'excitation et les fonctions d'onde; (ii) il faut que l'etat fondamental donne satisfasse au theoreme du viriel; (iii) dans l'operateur hyperviriel utilise ici comme xm, les valeurs les plus petities de m donnent les meilleurs resultats; (iv) l'utilisation d'un nombre relativement restreint de fonctions de base de type exp (−γ|x|) suffit pour reproduire l'etat excite exact. Surtout la seconde condition est importante. Tenant compte de ces points-ci on a obtenu pour les deux premiers etats excites des resultats sensiblement ameliores pour l'energie d'excitation, la fonction d'onde et d'autres quantites physiques comme les moments de transition et les forces d'oscillateur. On trouve aussi que la methode presentee ici est plus efficace que l'emploi des relations hypervirielles non-diagonales seules ou la methode de Gopinathan. Die effektive Anwendung der Hypervirialrelationen wird detailliert untersucht, um angenaherte Wellenfunktionen fur angeregte Zustande des harmonischen Oszillators zu verbesseren. Eine neue Methode wird vorgelegt, die gleichzeitig die nicht-diagonalen und die diagonale Hypervirialrelationen verwenden. Um diese Relationen effektiver anzuwenden werden folgende Punkte unterstrichen: (i) die neue Methode gibt bessere Resultate fur die Anregungsenergien und die Zustandsfunktionen; (ii) der gegebene Grundzustand muss den Virialsatz erfullen; (iii) in dem hier benutzten Hypervirialoperator xm geben kleinere Werte von m bessere Resultate; (iv) die Verwendung einer relativ kleinen Anzahl von Basisfunktionen von Typ exp (−γ|x|) genugt um den exakten angeregten Zustand zu reproduzieren. Besonders die zweite Bedingung ist wichtig. Unter Berucksichtigung dieser Observationen sind fur die zwei ersten angeregten Zustande betrachtlich verbesserte Ergebnisse fur die Anregungsenergie, Wellenfunktion und andere physikalische Grosse wie z.B. Ubergangsrnomente und Oszillatorenstarke erhalten worden. Die vorgelegte Methode ist auch effektiver als die Anwen-dung der nicht-diagonalen Hypervirialrelationen allein oder der Methode von Gopinathan.

Fabrication of Superconducting Bridges on Nb Film

Abstract: A simple technique for micromachining and its application to the fabrication of Nb based superconducting bridges are described. The technique is based on the use of oblique deposition of SiO film for the mask of anodization. By this technique variable thickness bridges with the length of about 0.1 to 1 μm have been successfully fabricated. Superconducting properties of a bridge with the length of about 0.3 μm are descrived. Zero voltage current is obserbed up to 7.2 K which is about 3 K above the critical temperature of thinned region of Nb film. Microwave induced steps on the V-I curve are also observed. The technique described in this paper is found to be suitable for the fabrication of variable thickness bridge type Josephson junctions.

Quantum Theory of a One-Dimensional Optical Cavity with Output Coupling. IV. The Fluctuation-Dissipation Theorem in an Arbitrarily Stratified Structure

Abstract: Chaotic fields in a general class of one-dimensional optical cavity having output coupling is considered. The fluctuation-dissipation theorem is derived assuming that the cavity materials are lossless. The cavity admittance probed by a prescribed current source for an arbitrarily stratified optical cavity is calculated and using the explicit expression for the admittance the “dissipation” is proved to be equal to the radiation loss. The form of the fluctuation-dissipation theorem for a restricted frequency region around a cavity mode is discussed with particular attention to the cavity mode degeneracy.

Electromechanical Properties of the Ferroelectric Crystal NaH 3 (SeO 3 ) 2 near the Curie Point

Abstract: Elastic compliance constants (at constant electric field) s 11 E , s 22 E and s 33 E and electromechanical couplins factors k 12 and k 13 have been measured in NaH 3 (SeO 3 ) 2 near the Curie point, -79°C. A new theory, which takes account of elastic nonlinearity or the third elastic constants, is proposed to explain the change of s D (at constant electric displacement) below the Curie point. This theory is valid for most of the elastic anomalies in ferroelectric crystals.