A linear electronic scanning type of ultrasonic imaging method, in which comb electrodes on a piezoelectric thin plate are successively operated, is described. A PbTiO3 ceramic plate is used as a piezoelectric substrate because of its large piezoelectric anisotropy. A region between a comb electrode and a counter electrode operates as an equivalent thickness-mode vibrator. Calculation results on acoustical field distributions are well in accordance with experimental results. The field distribution from the transducer is valid for obtaining the agreement of two orthogonal focul points. A C-mode ultrasonic imaging system is constructed by a combination of electronic and mechanical scanning in two orthogonal directions. The obtained imaging results support that this method is useful for high speed scanning in the field of nondestructive testing.
In accordance with rapid increase of industrial microwave application on heating, more and more high power microwave sources are required. Among many microwave devices, magnetron is most advantageous in economical point of view. Responding to these requirements, a super high power magnetron with output power of 420kW in CW which will be the largest in the world at this time, objective power being 500kW, was developed. In this paper, the design principle, the construction and the scale of each parts are described. The measured characteristics of the developed device reveal satisfactory.
We consider the problem of representing and learning of continuous complex patterns in the 2-dimensional space by muli-layer networks. We propose a new network architecture, high-order functional networks with Chebychev polynomials as input units. It is shown that the structure of characterizing continuous patterns can be generalized by the high-order functional networks that are trained with backpropagation. The property of extracting the specific features of continuous patterns without losing the essential meanings of their original patterns is indispensable to many pattern information processing problems. We propose a structural pattern classification method with high-order functional networks. We apply this methodology to the task domain of a speech recognition and show its advantages over the traditional non-structural approach.
In the previous paper, “Repetitive Inverse Transit Time Difference (RITTD) Method” was proposed as a method to measure velocity and temperature of water with ultrasonic wave. In this paper, the previous apparatus has improved, and as a result of that the velocity resolution of 0.5mm/s and the measuring time of 50ms have achieved. Its response has been confirmed by the measurement of the velocity of fluctuation for the Karman vortex street in the flow past a circular cylinder. The Strouhal number is calculated from the measured velocity of fluctuation. Our results correspond with the facts of all other experiments concerned with the Karman vortex street. This method can be possible to apply as a vortex flowmeter because of well response to the velocity of fluctuation in a few Hz.
This paper proposes a simple new model for the recognition of vowel sequences by a neural network using vocal tract area. Utilizing vocal tract area as input data reduces the number of input units and requisites computational time of learning compared with utilization of frequency spectrum. Practically, back-propagation rule is applied on three-layer structure, and suitable prediction of vocal tract area makes it possible to recognize speaker-independent vowel sequences by 39 units which is comparatively small as the number of total units.
In this paper, we consider optimal control problems for a class of nonlinear descriptor systems. A necessary condition which may be regarded as the maximum principle for descriptor systems is derived, and some problems related to this necessary condition, such as the continuity and differentiability of the hamiltonian in this necessary condition, the sufficient and necessary condition on linear descriptor systems, and so on, are discussed. Our results may include some ones in optimal control problems for conventional systems. Finally, an illustrative example is also given.