Formulas are derived for the solution of the transient currents of dissipative low-pass T-type electric wave filters. Oscillograms taken by cathode ray oscillograph for d-c. and a-c. cases are found to agree with results calculated from these formulas. From these calculations, the following conclusions are derived. When terminating resistance is gradually increased from O, the damping constants of the sine terms begin to differ from each other, ranging in decreasing magnitude from term of the lowest frequency...

Formulas are derived for the solution of the transient currents of dissipative low-pass T-type electric wave filters. Oscillograms taken by cathode ray oscillograph for d-c. and a-c. cases are found to agree with results calculated from these formulas. From these calculations, the following conclusions are derived. When terminating resistance is gradually increased from O, the damping constants of the sine terms begin to differ from each other, ranging in decreasing magnitude from term of the lowest frequency to the last term of cut-off frequency. Hence the transient is ultimately of the cut-off frequency. At cut-off frequency, this constant is near to but greater than R/2L. For each increase of section, there is introduced an additional sine term with smaller damping constant. Therefore transients die out faster in filters of smaller number of sections. Since transient amplitudes are of the same order of magnitude before and after cut-off, filtering property only exists in the steady states.

Formulas are derived for the solution of the transient currents of resistance-terminated dissipative π-type low-pass, T- and π-type high-pass electric wave filters. Oseillograms taken by cathode ray oscillograph for d-c. and a-c. cases are found to agree with the results calculated from these formulas. From these calculations, the following conclusions are derived: (1) When the terminating resistance is gradually increased from 0, the damping constants of the damped sine terms begin to differ greatly from...

Formulas are derived for the solution of the transient currents of resistance-terminated dissipative π-type low-pass, T- and π-type high-pass electric wave filters. Oseillograms taken by cathode ray oscillograph for d-c. and a-c. cases are found to agree with the results calculated from these formulas. From these calculations, the following conclusions are derived: (1) When the terminating resistance is gradually increased from 0, the damping constants of the damped sine terms begin to differ greatly from each other, ranging in decreasing magnitudes from the first damped sine term to the last term of cut-off frequency. Hence the transient is ultimately of the cut-off frequency. At the cut-off frequency, this constant is greater than the corresponding constant (R/2L) when the termination is absent. (2) For each increase of one section, there is introduced an additional damped sine term with smaller damping constants. Therefore transients die out faster in filters of small no. of sections. (3) With the same network constants, the damping constants of π-type filters are greater than the corresponding values of T-type filters. As a result, transients die out faster in π-type filters. (4) The amplitudes of the transient terms in the attenuation and transmission ranges are of the same order of magnitude, and the filtering property only exists in the steady states. (5) The cut-off frequency of the π-type filters varies with the no. of sections used. When only two sections of low, or, high-pass filter are used, the variation amounts to nearly 26 per cent from the theoretical value.

Black rot of yam bean has been collected from the market in certain localities of Yunnan Province.The diseased tuber-root is characterized by the black dis- coloration of the interior tissues without conspicuous external symptoms.The evidence at hand indicates that the infection takes place before the digging time, through the dead main tap roots.It is unlikely that it works in the storage. Hundreds of isolations were made from the diseased tuber-roots and one fungus,a species of Pythium,predominated.The morphologic...

Black rot of yam bean has been collected from the market in certain localities of Yunnan Province.The diseased tuber-root is characterized by the black dis- coloration of the interior tissues without conspicuous external symptoms.The evidence at hand indicates that the infection takes place before the digging time, through the dead main tap roots.It is unlikely that it works in the storage. Hundreds of isolations were made from the diseased tuber-roots and one fungus,a species of Pythium,predominated.The morphologic and cultural char- acters of this causal fungus closely resemble those of Pythium spinosum,described by Sawada in 1927. Inoculations of yam bean seeds were made by sowing them in soils mixed with pure cultures of the causal fungus.It did not cause preemergence of in- fection several weeks after inoculation.Elongate black lesions were found on the basal stems.The fungus caused neither damping-off nor wilt of young seed- lings. Healthy tuber-roots of yam bean were selected and cleaned.After inserting hyphae and spores beneath the epidermis,they were laid in a moist chamber. Black discoloration of the interior tissues developed in the course of about three weeks.The discolored area enlarged but very slowly.The results of these ino- culation experiments indicate that Pythium spinosum Saw.is very weakly parasitic to yam beans. Occasionally,as might be expected,certain other species of fungi were isolated from the diseased tuber-roots.Among them were found two other species of Pythium,identified respectively as P.irregulare Buisman and P.intermedium de Bary.However,inoculations of tuber-roots of yam bean with these fungi failed to produce the characteristic symptoms. Besides from yam beans,a species of Pythium was isolated from the roots of broad bean(Vicia fabae L.).Despite certain minor morphologic differences,it has been identified as P.spinosum Sawada.However,no cross inoculation ex- periments have been conducted.