Showing papers by "University of Electro-Communications published in 1988"
TL;DR: A new technique is proposed, in which the transport equation is solved by the Fourier transform method for a periodic boundary condition with high spatial carrier frequency, which is created by making a light beam with unknown phase distribution pass through a grating.
Abstract: Experimental demonstrations of deterministic phase retrieval based on the Teague-Streibl irradiance transport equation are presented. A new technique is proposed, in which the transport equation is solved by the Fourier transform method for a periodic boundary condition with high spatial carrier frequency, which is created by making a light beam with unknown phase distribution pass through a grating. Quantitative phase measurements were performed by experiments without recourse to interferometry, and the results were found to be in good agreement with theory.
97 citations
TL;DR: The least achievable distortion of the secondary decoder is evaluated for the most secure primary system and security is evaluated by distortion measures instead of the equivocation function used by H. Tamamoto (1983).
Abstract: A rate-distortion problem is considered for a communication system (f, phi /sub 1/) with a secondary decoder phi /sub 2/ to be hindered which uses a different distortion measure from the primary system. The least achievable distortion of the secondary decoder is evaluated for the most secure primary system. Source coding for sources with additional outputs to be kept secret from the receiver or wiretappers is also discussed. Security is evaluated by distortion measures instead of the equivocation function used by H. Tamamoto (1983). >
73 citations
TL;DR: In this article, the transient response of a lossless transmission line of finite length excited externally by an electromagnetic wave of an arbitrary waveform is studied, and a solution of the transient current is obtained as a series of analytical functions.
Abstract: The transient response of a lossless transmission line of finite length excited externally by an electromagnetic wave of an arbitrary waveform is studied. By using the Laplace transformation, a solution of the transient current is obtained as a series of analytical functions. Inspection of the solution leads to the conclusion that the response currents at terminals of the line can be equivalently expressed by the components induced at both terminals, and, in addition, the multireflected wave when the line is mismatched. Furthermore, a new equivalent circuit for the coupling phenomenon is discussed. >
40 citations
TL;DR: The results of magnetic and X-ray studies have led to a conclusion that the high-temperature ϵ phase of MnGe system, which has D019 type of structure, has the homogeneity range 22.7-24.0 at.% Ge at 800°C and is metastable below ∼515°C as discussed by the authors.
Abstract: The results of magnetic and X-ray studies have led to a conclusion that the high-temperature ϵ phase of MnGe system, which has D019 type of structure, has the homogeneity range 22.7–24.0 at.% Ge at 800°C and is metastable below ∼515°C. The Curie temperature, asymptotic Curie temperature, the Curie constant and the effective magnetic moment per Mn of the weak ferromagnetism, which is parasitic on a triangular antiferromagnetism, are 365 K, -853 K, 2.39 × 10−2 K cm3/g and 3.89 μB, respectively, for 23.5 at.% Ge. The study on a single crystal with 23.0 at.% Ge confirmed that the spontaneous magnetization lies within the basal plane, with zero-field magnetic moment of 0.007 μB/Mn and nearly isotropic incremental susceptibility of 2.0 × 10−5cm3/g, in substantial agreement with the theory by Nagamiya et al.
33 citations
TL;DR: In this paper, the two-degree-of-freedom monocycle is modeled by an inverted pendulum with a controlling arm pivoted at its upper end and it is found that the optimal control method is superior to the pole assignment one.
Abstract: This is a preliminary study to provide useful information for the design of the control of a monocycle which is one of the intelligent movable robots. In this paper, the two-degree-of-freedom monocycle is modeled by an inverted pendulum with a controlling arm pivoted at its upper end. The controlling arm is rotated to give the pendulum restoring moment.The feedback control systems for the model have been designed using two methods – the pole assignment and the optimal control, respectively. Simulations of the control systems designed with the above methods are carried out on a personal computer. Although the pendulum can be stabilized with either of these methods, it is found that the optimal control method is superior to the pole assignment one, because in the former the control system can be designed to be suitably corresponding to the design demands based on a definite criterion.
30 citations
TL;DR: In this article, the authors considered a Markov chain with transition densities whose state space is a Euclidian space and showed that it is reversible with respect to some density, and time-reversible or not.
18 citations
TL;DR: In this article, an autonomous mobile robot for obstacle avoidance based on finding permissible passageways using the edges between the floor and the wall or obstacles obtained by processing the image from a CCD camera in front of the robot is developed.
Abstract: Autonomous mobile robots should have the capability of recognizing their environments and manoeuvring through those environments on the basis of their own judgement. Fuzzy control is suitable for autonomous mobile robot control where the amount of information to be handled is limited as much as possible and the processing is simple. Autonomous mobile control of a robot is derived from two kinds of controls: for obstacle avoidance and for guidance following an appropriate path to a destination point. Fuzzy control of a robot for obstacle avoidance based on finding permissible passageways using the edges between the floor and the wall or obstacles obtained by processing the image from a CCD camera in front of the robot is developed. Furthermore, guidance control of the robot over paths that are specified in terms of maps may be developed by a process that treats a wrong path as a virtual obstacle on the screen, and the robot advances in the designated direction when it reaches intersections. An autonomous f...
18 citations
TL;DR: In this article, the triplet-triplet energy transfer process from xanthone to naphthalene was studied in a γ-cyclodextrin system at 77 K using a time-resolved ESR method.
16 citations
TL;DR: In this article, a statistical model for the electron localization-delocalization transition in mixed-valence biferrocenium trihalide trihalides was proposed, and the temperature dependences of the physical quantities relevant to the cooperative electron localization and localization transition were calculated based on the model.
Abstract: Intramolecular electron transfer in the mixed-valence biferrocenium complexes in crystals shows qualitatively different behavior from that in the complexes in solutions. The ‘extra’ electron in a mixed-valence complex in the crystal may be localized at low temperature and delocalized at higher temperature. The electron localization-delocalization transition induced thermally corresponds to a kind of order-disorder phase transition. In order to clarify the mechanism of the transition, a statistical mechanical model has been proposed (T. Kambara, D.N. Hendrickson, T.-Y. Dong, and M. J. Cohn, J. Chem. Phys., 86, 2362 (1987)). The temperature dependences of the physical quantities relevant to the cooperative electron localization-delocalization transition are calculated base on the model. In the calculation a more elaborate treatment is adopted for the intermolecular interactions. Those calculated values are compared with the observed ones for various kinds of mixed-valence biferrocenium trihalide cr...
14 citations
TL;DR: In this article, the surface tension of liquid 3He has been measured using a capillary-rise method between 0.4 K and 15 mK, and the deviation does not depend on 4He impurity concentration nor on experimental conditions, but seems to be partly related to the decrease of the zero-point energy of the surface due to a decrease in density of the liquid.
Abstract: Surface tension of liquid 3He has been measured using a capillary-rise method between 0.4 K and 15 mK. Data as a function of temperature T do not exhibit the T2-dependence as expected from the behaviour above 0.3 K. They deviate downwards below about 150 mK and become almost constant below 100 mK. The deviation does not depend on 4He impurity concentration nor on experimental conditions, but seems to be partly related to the decrease of the zero-point energy of the surface due to the decrease in density of the liquid.
14 citations
TL;DR: In this paper, a first-principle calculation in which the Euler equation is solved using Newton's method is presented. But the method of calculation and the results are presented.
Abstract: Detailed micromagnetic structures around a three-dimensional vertical Bloch line and Bloch points of circulation and contracirculation types are obtained from a first-principle calculation in which the Euler equation is solved using Newton's method. The computing region consists of 21*21*21 cells extending in x (wall normal), y and z (film normal) directions. To avoid situations in which the polar angle theta of the magnetization vector approaches 0(mod pi ), a proper-coordinates frame is selected at each cell and each calculation step from the conventional system xyz and a subsidiary system XYZ with the Z axis lying in the film plane. The method of calculation and the results are presented. >
TL;DR: In this paper, the annealing of Si-C mixtures prepared by ion beam techniques was studied using IR absorption spectroscopy, and the activation energy for the β-SiC formation process was discussed in connection with the formation of continuous amorphous layers during mixing.
TL;DR: In this paper, the displacement and electric potential fields produced by moving dislocations in anisotropic piezoelectric crystals were treated by using the method of Green's potential functions.
TL;DR: In this paper, the authors used multi-spacecraft observations in the interplanetary space to build up a picture of the distribution of solar wind velocities in heliographic latitude and longitude.
TL;DR: In this article, a comparative analysis of the growth processes of antimony layers on two types of amorphous substrate: collodion films and carbon films was carried out, focusing on the effect of the pre-irradiation with the surface.
TL;DR: In this paper, four isomeric benzodithiophene analogues of TCNQ have been prepared and their physico-chemical properties were investigated and the crystal structures of these complexes were determined by an X-ray method, revealing a novel mixed stack of DD-AA-DD- with a sheet-like network comprised of the side-by-side arrangement of the donor and acceptor molecules.
TL;DR: The Ramsey number r(G, H) is defined to be the least positive integer m such that if the edges of the complete graph km are colored red and blue, then either the red graph contains G as a subgraph or the blue graph contains H.
TL;DR: The fine and hyperfine structure intervals of 2 3 P and 2 1 P states of 3 He are calculated by use of 165-term Hylleraas type wavefunctions as mentioned in this paper.
Abstract: The fine and hyperfine structure intervals of 2 3 P and 2 1 P states of 3 He are calculated by use of 165-term Hylleraas type wavefunctions For 2 3 P the levels denoted by | J F > are found to be |2, 5/2>, |1, 3/2>, |1, 1/2>, |2, 3/2> |0, |1/2> in the ascending order of energy and the corresponding intervals are 17810, 45122, 6682 and 274135 MHz 3 P 1 and 3 P 2 are hybridized strongly into |1, 3/2> and |2, 3/2> In 1 P 1 |1, 1/2> is above |1, 3/2> by 203 MHz The accuracy of the calculation is checked and it is found that the maximum error may interfere the digit of 1 MHz
01 Jan 1988
TL;DR: In this paper, the authors determined the fundamental group of an irreducible semisimple symmetric space G/H when G is a connected semi-simple Lie group with trivial center.
Abstract: The aim of this report is to determine the fundamental group of an arbitrary irreducible semisimple symmetric space G/H when G is a connected semisimple Lie group with trivial center The fundamental group π1(G/H) is well-known if G/H is Riemannian Therefore, we restrict our attention to the case where G/H is non-Riemannian so both G and H are not compact The result is summarized in Table 4
TL;DR: In this paper, the authors directly observed the crystallization process of an amorphous antimony layer 3.4-8.9 nm in a cover glass in a vacuum of 3 × 10 −4 Pa.
TL;DR: In this article, the second order asymptotic distribution of a bias-adjusted maximum likelihood estimator was shown to be not generally second-order asymPTotically efficient, and the bound for the secondorder median unbiased estimators was established.
Abstract: We consider i.i.d. samples from a continuous density with finite cusps. Then we obtain the bound for the second order asymptotic distribution of all asymptotically median unbiased estimators. Further we get the second order asymptotic distribution of a bias-adjusted maximum likelihood estimator, and we see that it is not generally second order asymptotically efficient.
TL;DR: In this article, the spatial correlation between fluctuations as a function of the azimuthal separation of the points has been measured and it has been found that the two-point angular correlation reflects the pattern of modulation, and falls off as (Rd - R)σ when the ''disorder Reynolds number' Rd is approached.
TL;DR: In this paper, the total energies of 2 3 P and 2 1 P, the relativistic and the mass corrections, and the fine and hyperfine structure for the helium isoelectronics (from 3 He to 21 Ne 8+ ) having nuclear spins I = 1/2.
Abstract: On the basis of 165-term Hylleraas type wavefunctions, the total energies of 2 3 P and 2 1 P, the relativistic and the mass corrections, and the fine and hyperfine structure are calculated for the helium isoelectronics (from 3 He to 21 Ne 8+ ) having nuclear spins I =1/2. 1 and 3/2. The accuracy of the calculation is examined by comparing the results with the experimental data for fine structure splitting of all the ions and for the hyperfine splitting of 6 Li + and 7 Li + . Complete tables of the hyperfine structures are given for all the ions. The effect of 1 P- 3 P mixing is discussed.
TL;DR: In this article, the phase conjugation of planar planar guided waves in dielectric and metal structures is considered, and the expression for the phase-conjugate gain is derived.
Abstract: Four-wave mixing and two-dimensional phase conjugation of planar guided waves in dielectric–nonlinear dielectric–metal or dielectric–nonlinear dielectric–dielectric structures is considered, and the expression for the phase-conjugate gain is derived. The effectiveness of the nonlinear polarization, with different vectorial structure and different intensity distribution from those of generated phase-conjugate wave, is evaluated by considering the energy balance. Formulas for phase-conjugate gain are given for various wavelengths and for various guiding modes. Also, the dependence of the phase-conjugate gain on the crossing angle between pump beams and the probe beam is analyzed. By model calculation it is shown that the relative effective gain is large for TE modes with dielectric substrates but is small for TM modes with metal substrates.
TL;DR: In this paper, the effect of micropores on the electric properties of porous titania glass (PTG) electrodes in aqueous electrolytes was studied systematically paying special attention to the effects of micro-pores in the material.
TL;DR: In this article, the photoabsorption cross section of the Ar2F excimer in the lowest excited state (42Γ), which is produced by exciting an Ar/F2 gas mix by a short-pulse relativistic electron beam, has been determined at 248 nm to be (3.3 ± 1) × 10−18 cm2 by observing the depletion of Ar 2F fluorescence induced by the irradiation of a shortpulse KrF laser beam.
Abstract: The photoabsorption cross section of the Ar2F excimer in the lowest excited state (42Γ), which is produced by exciting an Ar/F2 gas mix by a short-pulse relativistic electron beam, has been determined at 248 nm to be (3.3 ± 1) × 10−18 cm2 by observing the depletion of Ar2F fluorescence induced by the irradiation of a short-pulse KrF laser beam. Observation of ArF fluorescence shows that the Ar2F excimer is directly dissociated into ArF and Ar by absorbing a 248-nm photon.
01 Jan 1988
TL;DR: In this article, a new method of recognizing the bearing of workpieces and the development of a scraping robot was proposed to rationalize the automation of scraping works, which take much time and skill.