Observations of Oscillating Cavitation on a Flat Plate Hydrofoil

An experimental investigation was made to clarify the characteristics of oscillating cavitation on a flat plate hydrofoil in a water tunnel. Dynamic the behavior of oscillating cavitation is discussed from the unsteady pressure measurements at the upstream of the blade and the visual observations of cavitation phenomena using high-speed video recording. It was found that the mean cavity length characterizes the fundamental characteristics of cavity oscillation. The cavity oscillations are categorized into two types, i.e. the transitional cavity oscillation and the partial cavity oscillation

Feeding Habits of the Tomato Bug, Cyrtopeltis (Engytatus) modestus (Distant), with Special Reference to the Feeding Lesion on Tomato

The present study concerns the feeding habits of the tomato bug, Cyrtopeltis (Engytatus) modestus (Distant), and the unusual feeding lesions produced on tomato plants. Existing information on the feeding habits and the taxonomic status of this insect have been incorporared in this bulletin. During the five-year period of this study, 1940-1945, the tomato bug was a serious pest of tomato in Hawaii and was difficult to control with the insecticides available at that time. At present it is effectively controlled by DDT

Microcomputer Filtering System to Measure Very Small Transmission Loss of Impulsive Signals

This paper describes a method for measuring very small transmission loss of impulsive signals. The correlative fluctuations within input and output signals are eliminated effectively by the analog simultaneous differencer. The difference and normal signals are alternately sampled and accumulated by the digitizer and the microcomputer, that is, the microcomputer 2-channels box-car integrator is realized. The difference and normal accumulated data are transferred to the personal computer, which calculates the ratio of the difference to normal accumulated data, i.e. the estimated attenuation in nepers. By the experiments of electrical and optical impulse transmissions, the minimum measurable attenuations become respectively 2.7×10(-4)NP and 6.0×10(-4)Np. Even the latter value is the smallest so far as the authors know

A Walsh Waoofonn Analyzer and Its Applications to Filtering of Pulse Signals

A new waveform analyzer based on the Walsh transform　is developed and is applied to a real-time filtering of fast pulse signals, and the linear filterings　of time signals through the Walsh transform is　discussed. The analyzer converts a solitary waveform during 16 μs into the 16 Walsh amplitude spectra in a hybrid manner: it has the sequency band from 62.5 kzps to 500 kzps. The spectra are parallelly held during 16 μs by analog integrators, while serially displayed by the CRT, and one of them is digitally read out. The spectra of the test waves are measured within the error rate of several per cent. The analyzer is applied to the correlative detection of the photoelectric pulse signals in a gasspectroscopic system using a pulse laser, and there composes the matched filter, which is useful for measuring the signals superposed by Gaussian noises with a high accuracy. For the real-time filtering of fast signals, the arithmetic convolution and the frequency power spectra are approximated using the complex Walsh transform. These approximations are of practical use in 16 or 32 dimensions. Then, the matched filters for pulse peaking are given by the approximate convolution and by the dyadic convolution

Smoothing of Impulse Noise by Orthogonal Transform

Electromagnetic impulse noise which is harmful to signal measurement or transmission of information, is smoothed by the orthogonal transform processor. The idealized impulse noise with infinitesimal duration and Gaussianly-distributed amplitude shows the same spectral characteristics as white Gaussian noise. Optimal correlation detector against such noise is easily realized by the orthogonal transform processor. Photoelectric pulse signals disturbed by the impulse noise from the power supply can be well detected through the Walsh waveform analyzer. Also, orthogonally-synthesized signals can be demodulated with firmly-suppressed impulse noise, where both the statistical and instantaneous SNRs are superior to those in the usual PCM transmission system

Response of Electromagnetic Deflection for CRT Display

In the CRT display system of high-speed electromagnetic deflection, the tendency to amplifier saturation should not be neglected. We first show the limitation to the linear characteristics of input-output response and the response time under the saturation condition in this system. We try to improve the frequency-characteristics of the amplifier by making the load resistance constant and the feedback-paths partially positive, and reduce the L/R value of the load circuit by adopting the mutually-coupled yokecoils and the low-current amplifier. As the result, it is suggested that a low-power dissipation and highspeed response electromagnetic deflection system can be constructed

Transmission Distance and Bit Rate in an Optical-Fiber Multi-Level PCM Transmission System

Optical-fiber multi-level PCM transmission system is investigated on the transmission distance and bit rate. A communication channel is established as follows: a light signal is modulated in intensity with a completely-balanced M-Ievel code at a transmitter, and is propagated over an optical glass fiber, and is demodulated at a receiver where the signal with an additive noise is processed through a PD, an equalizing amplifier, a matched filter, (M-l) comparators and a decision circuit. The relative power of the noise from the amplifier is increased in accordance with the reciprocal of fiber's transmittance, where shot noise and thermal noise are smoothed and decreased in power by the matched filter. The relation between the BER and the SNR leads the transmission distance. The product of the transmission distance and bit rate takes the large maximum at the large values of SNR and M. The large value of M is suitable for low-speed and high-rate system, and the interference system