Showing papers by "Osaka University published in 1984"

Bettering Operation of Robots by Learning

Abstract: This article proposes a betterment process for the operation of a mechanical robot in a sense that it betters the next operation of a robot by using the previous operation's data. The process has an iterative learning structure such that the (k + 1)th input to joint actuators consists of the kth input plus an error increment composed of the derivative difference between the kth motion trajectory and the given desired motion trajectory. The convergence of the process to the desired motion trajectory is assured under some reasonable conditions. Numerical results by computer simulation are presented to show the effectiveness of the proposed learning scheme.

Random Phasing of High-Power Lasers for Uniform Target Acceleration and Plasma-Instability Suppression

Abstract: By converting a coherent wave to a random-phased wave, the intensity profile on a target becomes easily controllable. Planar as well as spherical targets were irradiated for the first time by the random-phased wave. The targets were uniformly accelerated without being affected by the small-scale intensity nonuniformities. The $\frac{3}{2}$-harmonic emission shows that the plasma waves at $\frac{{n}_{c}}{4}$ are only weakly excited in a spherical plasma. Irradiation with short-wavelength, random-phased beams will be suitable for compression.

LDV measurements of an air-solid two-phase flow in a vertical pipe

Abstract: Measurements of air and solid-particle velocities were made in a vertical pipe two-phase flow by the use of a laser-Doppler velocimeter (LDV). Five kinds of plastic particles, diameters of which ranged from about 3 mm to 200 μm, were transported in a vertical pipe of 30 mm inner diameter. It was found that, the smaller the particle size, the flatter was the mean air velocity distribution for the same mass flow ratio of solids to air. Large particles increased air turbulence throughout the pipe section, while small particles reduced it. Both effects of promotion and suppression of turbulence were observed at the same time in the presence of particles of medium size, that is, the turbulence was increased around the pipe centre and reduced near the wall. The frequency spectrum of air turbulence normalized by the turbulence intensity was not changed by the large particles. In the presence of the small particles, the higher-frequency parts of the spectrum increased.

Direct observation of motion of single F-actin filaments in the presence of myosin.

Abstract: Actin is found in almost all kinds of non-muscle cells where it is thought to have an important role in cell motility A proper understanding of that role will only be possible when reliable in vitro systems are available for investigating the interaction of cellular actin and myosin A start has been made on several systems, most recently by Sheetz and Spudich who demonstrated unidirectional movement of HMM-coated beads along F-actin cables on arrays of chloroplasts exposed by dissection of a Nitella cell As an alternative approach, we report here the direct observation by fluorescence microscopy of the movements of single F-actin filaments interacting with soluble myosin fragments energized by Mg2+-ATP

Band Structure in the High Temperature Phase of Fe 3 O 4

Abstract: Band structure of the ferrimagnetic Fe 3 O 4 was calculated in the high temperature cubic phase by means of self-consistent APW method. Though the obtained band structure corresponds closely with the ionic Neel model, it was shown that the itinerant electron model is more adequate than the localized electron model. The minority spin d e bands of B site iron have an electron Fermi surface at the \( \varGamma \) point and hole surfaces around the W point. Experimental data including photoelectron emission, optical reflectivity, neutron scattering and transport phenomena were discussed qualitatively in relation to the calculated band structure.

Bettering operation of dynamic systems by learning: A new control theory for servomechanism or mechatronics systems

Abstract: A new concept called "betterment process" is proposed for the purpose of giving a learning ability of autonomous construction of a better control input to a class of multi-input multi-output servomechanism or mechatronics systems such as mechanical robots. It is assumed that those dynamic systems can be operated repeatedly at low cost and in a relatively short time under invariant initial physical conditions, but the knowledge on precise description of their dynamics is not required. The betterment process is composed of a simple iteration rule that generates autonomously a present actuator input better than the previous one, provided a desired output response is given. The convergence of iteration is proved for a simple betterment process where the k+1th input is composed of the kth input plus an increment of the derivative error between the kth output response and given desired response. Discussions on potential applications of the proposed theory to controlling robots or other mechanical systems are presented together with future subjects to be investigated.

Reexamination of the pyridylamination used for fluorescence labeling of oligosaccharides and its application to glycoproteins.

Abstract: The pyridylamination reaction of sugar chains from glycoproteins was re-investigated to raise the total yield of pyridylamino sugars. Sugar chains of glycoproteins were released by hydrazinolysis, and free amino groups were N-acetylated. The sugar chains were coupled with 2-aminopyridine, and the pyridylamino derivatives thus obtained were purified by Sephadex G-15 column chromatography and analyzed by high performance liquid chromatography. In this study, conditions for the coupling reaction (temperature, time, pH, concentration of 2-aminopyridine, and amount of the reducing reagent) were re-investigated. Under the conditions established in the present study, the total recovery of pyridylamino derivatives of sugar chains of glycoproteins was about 70%, and 0.15 nmol of a glycoprotein was enough to detect the pyridylamino derivatives of sugar chains. The stability of sialyl and fucosyl linkages under the present conditions was also studied.

Robust stabilizability for a class of transfer functions

Abstract: This paper is concerned with the robust stabilizability for single-input single-output plants. Robust stabilizability means that a fixed controller can stabilize simultaneously all the plants in a given class which is characterized by a frequency-dependent uncertainty band function around the transfer function of a nominal model. A necessary and sufficient condition for robust stabilizability is derived based on the well-known Nevanlinna-Pick theory in classical analysis. It is shown that the values of the uncertainty band function should be restricted within a certain range at the unstable poles of the nominal model, in order for the class to be robustly stabilizable. A procedure of synthesizing a robust stabilizer is given and the parametrization of all the robust stabilizers is also shown.

Phase Transition of the Two-Dimensional Heisenberg Antiferromagnet on the Triangular Lattice

Abstract: Ordering process of the antiferromagnetic Heisenberg model on the two-dimensional triangular lattice is studied both by topological analysis of defects and by Monte Carlo simulation. It is shown that the order parameter space of this model is isomorphic to the three-dimensional rotation group SO(3) due to the inherent frustration effect. Homotopy analysis shows that the system bears a topologically stable point defect characterized by a two-valued topological quantum number and exhibits a phase transition driven by the dissociation of the vortices. A Monte Carlo study on the specific heat and the behavior of vortices strongly suggests the occurence of a Kosterlitz-Thouless-type phase transition. It is, however, argued that in contrast to the two-dimensional X Y model, the spin-correlation function decays exponentially even in the low-temperature phase. In order to distinguish the high- and low-temperature phases qualitatively, we introduce a “vorticity function” analogously to the Wilson loop in the quark...

Structural study on ferroelectric phase transition of vinylidene fluoride-trifluoroethylene copolymers (III) dependence of transitional behavior on VDF molar content

Abstract: Structural changes occurring in the ferroelectric phase transition of vinylidene fluoride-trifluoroethylene (VDF-TrFE) copolymers with the various VDF molar contents have been investigated by means of X-ray diffraction and infrared spectroscopic methods. The phase transition occurs among three crystal phases of the low-temperature (regular all-trans conformation), the high-temperature (gauche conformation with a large rotational motion), and the cooled phases (disordered trans conformation). In the copolymer with low VDF molar content less than 40%, the broad transition between the cooled phase and the high-temperature phase is observed and the conformational change from trans to gauche is not so perfect. In the range of VDF 50–60%, the transition becomes more definite, and on the way of heating the low-temperature phase transforms to the cooled phase, which transfers continuously to the high-temperature phase. For copolymers of VDF 70–80%, a clear and discontinuous first order transition between...

An adsorption isotherm of multi-site occupancy model for homogeneous surface

Abstract: An adsorption isotherm for a heterogeneous surface is described on the basis of a multi-site occupancy model followed by a group-contribution assumption. Equations of single- and multi-component adsorptions are derived for systems of molecules consisting of several functional groups and a surface composed of active sites of different energies interacting with the groups independently. The isotherm equation reduces to the expression derived by Sparnaay in the special case where a molecule occupies one site of the surface. The theory is applied to adsorption equilibria for systems of oxygen, nitrogen, and carbon monoxide on Molecular Sieves 5A and 10X. Correlations of single-component isotherms are excellent for nitrogen and oxygen and fairly good for carbon monoxide; predictions of adsorption isotherms of binary gas mixtures are made satisfactorily by means of parameters determined from the best fit to each single-component isotherm.

Endotoxic properties of chemically synthesized lipid A part structures. Comparison of synthetic lipid A precursor and synthetic analogues with biosynthetic lipid A precursor and free lipid A.

Abstract: Synthetic lipid A part structures corresponding structurally to a biosynthetic lipid A disaccharide precursor have been analyzed for endotoxic activity in several systems in vivo and in vitro. It was found that a synthetic beta-1,6-linked D-glucosamine disaccharide, which carries four molar equivalents of (R)-3-hydroxytetradecanoyl residues in positions 2, 3, 2' and 3' and phosphoryl groups in positions 1 and 4' (preparation 406), exhibited lethal toxicity, B lymphocyte mitogenicity, the capacity to engender prostaglandin formation in macrophages and to induce endotoxic tolerance, as well as serological lipid A antigenicity. On a weight basis, preparation 406 was of comparable activity to lipid A precursor and bacterial free lipid A. Preparation 406, like lipid A precursor, lacked, however, the ability to induce the local Shwartzman phenomenon and both preparations were of moderate pyrogenicity. Two further synthetic analogues which contained only one phosphoryl group (preparation 404 at C-4', preparation 405 at C-1) showed comparable or diminished activity depending on the test system employed, except in the capacity to inactivate complement where they exhibited, in contrast to preparation 406, significant activity. The results show that the endotoxic principle of lipopolysaccharides, as postulated previously is embedded in the lipid A component. Our results also suggest initial conclusions on the structural requirements for the expression of endotoxin activities.

Transcatheter chemo-embolization effective for treating hepatocellular carcinoma. A histopathologic study

Abstract: A histopathologic study was done on livers from 14 patients who underwent surgery for hepatocellular carcinoma and who had been pretreated by a combination of intra-arterial embolization of Gelfoam (Upjohn) plus intra-arterial chemotherapy. This technique was effective as the excess vascularity of the tumor and the tumor bulk were reduced and resection was readily facilitated. For solitary tumors of less than 4 cm in diameter, this approach was particularly effective. As this combined treatment almost invariably leads to liquefaction and necrosis of the tumor, the likelihood of metastases is diminished.

Virulence Factors of Streptococcus mutans and Dental Caries Prevention

Abstract: Streptococcus mutans possesses the abilities to adhere to pellicle-coated tooth surfaces and to form acids - two characteristics associated with the cariogenicity of this micro-organism. De novo synthesis of insoluble glucan by S. mutans glucosyltransferase from sucrose is essential in the adherence process. Therefore, agents which interfere with the adherence ability of S. mutans would be useful for controlling dental caries. In the present report, we have summarized our recent findings concerning virulence factors of S. mutans and means for prevention of S. mutans-induced dental caries.

On the decay of solutions to the linearized equations of electro-magneto-fluid dynamics

Abstract: The linearized equations of the electrically conducting compressible viscous fluids are studied. It is shown that the decay estimate (1+t)−3/4 inL 2(R 3) holds for solutions of the above equations, provided that the initial data are inL 2(R 3)∩L 1(R 3). Since the systems of equations are not rotationally invariant, the perturbation theory for one parameter family of matrices is not useful enough to derive the above result. Therefore, by exploiting an energy method, we show that the decay estimate holds for the solutions of a general class of equations of symmetric hyperbolic-parabolic type, which contains the linearized equations in both electro-magneto-fluid dynamics and magnetohydrodynamics.

Double-stranded Helix of xanthan in dilute solution: evidence from light scattering

Abstract: A sample of xanthan, a bacterial β-1,4-D-glucan with ionic side chains, and its sonicated fragments in 0.1 M aqueous NaCl and cadoxen at 25°C were studied by light scattering. Radii of gyration ‹S2›1/2 as a function of weight-average molecular weight Mw in these two solvents, combined with the values of about 2 for the ratio Mw (in 0.1 M NaCl)/Mw (in cadoxen), showed that xanthan dissolves as rodlike dimers in 0.1 M aqueous NaCl and as single flexible chains in cadoxen. The contour length per main chain glucose residue of the xanthan dimer was found to be 0.47±0.01 nm, which agreed with the pitch (per glucose residue) of the 51 double-stranded helix proposed for the crystalline structure of xanthan. Thus, it was concluded that the xanthan dimer in 0.1 M aqueous NaCl has the 51 double-stranded helical structure.

A construction of vector quantizers for noisy channels

Abstract: Recently, vector quantization has become noted as a highly efficient coding method of image and voice data. So far, many of the highly efficient coding problems, or service coding problems, have been studied separately from channel coding problems. This paper reconsiders vector quantization jointly optimizing source coding and channel coding, and proposes a new vector quantizer for noisy channels. Vector quantizers for binary symmetric channels are designed for memoryless Gaussian source, Gauss-Markov source and the real images, and are compared with the conventional vector quantizer which does not take account of channel errors. As a result, it is shown that the performance of the proposed vector quantizer is improved without adding the redundancy for error correction, and the improvement of the performance of the proposed vector quantizer for noisy channels over the conventional vector quantizer becomes significant for highly correlated sources and longer block length.

Input Variable Assignment and Output Phase Optimization of PLA's

Abstract: A PLA minimization system having the following features is presented: 1) minimization of both two-level PLA's and PLA's with two-bit decoders; 2) optimal input variable assignment to the decoders; 3) optimal output phase assignment; and 4) essential prime implicants detection without generating all the prime implicants.