A learning algorithm for saccade model with distributed feedback mechanism

In this paper we propose a new learning rule for a spatiotemporal neural network model of the primate saccadic system with a distributed feedback control mechanism. In our model the superior colliculus is represented as the distributed network model and it provides a dynamic control signal to a lumped brain stem model (Robinson–Gisbergen model). Distributed feedforward and feedback weights between the deeper layer of the superior colliculus model and the brain stem model are trained using a finite time interval learning rule based on a steepest descent method. Simulations are carried out on a 20-cell model for horizontal saccades using eye position feedback and velocity feedback, respectively. The model makes accurate saccades to all target locations over the range 2 to 15 degrees even if disturbance is added to the burst generator in the brain stem model. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 66–76, 1999.     

Hydrodesulfurization of dibenzothiophene over alumina-supported nickel molybdenum phosphide catalysts

The activity of nickel molybdenum phosphide catalysts was studied for the hydrodesulfurization of dibenzothiophene at 573 K and total pressure of 2.0 MPa. The Al₂O₃-supported NiMo phosphide catalysts were prepared by successive and simultaneous methods. The effect of the reduction temperature on the catalyst activity was also studied. The simultaneous preparation was determined to be the best method for the preparation of the active supported catalyst for dibenzothiophene HDS. The 623 K-reduced catalyst had the highest HDS rate of the catalysts. Nickel migrated from the inside to the surface during the reaction and promoted the HDS activity. The active species in the dibenzothiophene HDS and the oxidation states of Mo, Ni and P in the catalyst before and after reaction and of S after the reaction were studied on the basis of an XPS analysis.     

High-resolution elemental mapping of titanium oxide/aluminium oxide multilayer by spectrum-imaging

A spectrum-imaging technique based on scanning transmission electron microscopy combined with an electron energy-loss spectroscopy has been applied for the multilayer of amorphous titanium oxide and aluminium oxide layers on silicon substrate. We demonstrate the high-resolution elemental mapping and discuss the advantage of this method compared to an energy-filtering transmission electron microscopy. The main advantage is the absence of chromatic broadening, which allows the use of a large collection angle to acquire spectrum-image data and a wide energy window to integrate the core-loss signals. This suggests that the spatial resolution of elemental maps is mainly determined by the size of the electron probe.     

Vapor Pressure Measurements of Lanthanum–Bismuth Alloys by Mass-Spectrometric Method1

Vapor pressures of Bi₂ (g) over La_0.03 Bi_0.97 and two-phase mixtures of Bi+LaBi₂, LaBi₂+LaBi, LaBi+La₄Bi₃, La₄Bi₃+La₅Bi₃, and La₅Bi₃+La₂ Bi were measured in the temperature range from 795 to 1066K with a time-of-flight mass spectrometer equipped with a tungsten Knudsen cell. The vapor pressure of Bi₂(g) over the two-phase mixtures of La₂Bi+La could not be detected experimentally in this temperature range. The thermodynamic activity of bismuth was determined from the vapor pressure of Bi₂(g). Thermodynamic activities of lanthanum over alloys were derived from those of bismuth in the alloys in this study and that of lanthanum in the bismuth in a previous study by graphic integration of the Gibbs–Duhem equation. Thermodynamic quantities such as Gibbs free energy of formation, excess enthalpy, etc., were also calculated from the thermodynamic activities.