The main content of this paper:Firstly,the basic theory and characteristics of various frequency synthetic technologies and the mixed frequency synthetic technology of DDS+PLL have been introduced,and the method to expand frequency bandwide has been analyzed and compared.

In the paper, the way of detection of signal based on wavelet transform is researched, it analyses and processes signal of the various frequency at different scales.

The results show that resistivity of the films under the various frequency are approximately consistent with a pure C_(60) film, but the permittivity varied with the frequency for the pure C_(60) film is obviously distinguished from the composite films.

After complex geotechnical media dissemination, blasting seismic waves contain various frequency components of the interferential wave, because of stacking of the interferential wave, blasting vibration analysis to the frequency characteristics of signals have became very difficult.

In the paper are studied the way of the detection of signals based on wavelet transform and its analysis and processing of signals of various frequencies at different scales.

On the basis of design of DDS utilizing FPGA, it presented a method of realizing the altitude modulation by generating the main wave and the modulation wave respectively, and the frequency modulation by changing frequency tuning word of main DDS.

On the basis of design of DDS utilizing FPGA, it presented a method of realizing the altitude modulation by generating the main wave and the modulation wave respectively, and the frequency modulation by changing frequency tuning word of main DDS.

So, varied frequency plan and anti-interference technique have been used to improve the efficiency of wireless frequency,this pape mainly introduce the 1*3 cell frequency plan solution with an example.

The author measured the electromagnetic fields distribution of the transmissionlines, which have trees and buildings under the lines. The results showed that the treesand building have the ability of shield, especially for the power frequency electric fields,100k~3GHz RF electric fields, 100k~30MHz and 30MHz~1GHz RF magnetic fields,degrade 1~2 orders.

Reflection of individual typological features in the structure of spatial interaction of EEG waves of various frequency ranges

We discuss the correlations between the luminosities of radio pulsars in various frequency ranges and the magnetic fields on the light cylinder.

Various frequency-analysis methods were applied to the data series at 3737 and 5092 ?, where the light from the hot component made an appreciable contribution.

A bifurcation diagram revealing the types of magnetization dynamic states is constructed in various frequency intervals.

It is found that various frequency ranges differ in the property of stationarity.

The present study was undertaken with one dog, on whose cortex, at the region of the sigmoid gyrus, were imbedded two permanent electrodes known respectively as electrode A and electrode B. Under stimulation, electrode A gives movement of the left hind leg, and electrode B elicits movement of the toes of the left front leg.The main aim of the experiment is to determine the minimal strength in voltage for eliciting the first appreciable motor response, when the frequency of the stimulating current is under control....

The present study was undertaken with one dog, on whose cortex, at the region of the sigmoid gyrus, were imbedded two permanent electrodes known respectively as electrode A and electrode B. Under stimulation, electrode A gives movement of the left hind leg, and electrode B elicits movement of the toes of the left front leg.The main aim of the experiment is to determine the minimal strength in voltage for eliciting the first appreciable motor response, when the frequency of the stimulating current is under control. With an ordinary audio-oscillator to administer the stimulus frequencies, the range of frequencies utilized is 20—20,000 cycles.For the same frequencies, the minimal voltage for eliciting the motor response varies considerably from one sitting to another (see Table 1), but within the same sitting the same frequencies, even when repeated with many other frequencie intervening, require closely similar minimal voltages. Furthermore, a clear trend is always present in the relationship between the frequency of the stimulating. current and the minimal voltage necessary for eliciting the motor response, i. e., within the range of frequencies used (20—20,000), the middle frequencies need farsmaller stimulus strength in voltage than either the lower or the higher ones to elicit the same motor response.It was found that the minimal effective voltage is lowest for the 300—1,000. cycles region. Frequencies lower than 300 or higher than 1,000 need higher voltage. Furthermore, frequencies from 300 downwards and from 1,000 upwards are accompanied by progressively higher voltage. Electrodes A and B yield closely similar results (see Table 3 and Fig. 2). Thus, the frequencies from 300 to 1,000 cycles may be considered as possessing the most effective stimulus value.Besides the definite frequency-voltage relationship just mentioned, frequency affects the type of motor response as that frequencies of 100 and below 100 no longer elicit the regular response of the leg or the toes alone, but give rise to neck. movement in addition. Neck movement becomes eventually the only motor response to frequencies 50—20. With electrode A the above mentioned phenomenon. appeared with great regularity (see Table 4).When the experiment was over, the dog was killed and its brain examined histologically. It is seen that both electrodes are in the sigmoid gyrus of the right hemisphere, but they enter into different depths. Electrode A penetrates into between layer Ⅴ and layer Ⅵ, while electrode B penetrates only into layer (see Figs. 4 and 5).

This paper attempts to answer the following two questions: (1) Is it possible to derive the law of distribution of hydrological frequency theoretically(2) What type of distribution curve should be adopted as the model of hydrological frequency curve and how to determine their parameters? The results obtained may be summarized as follows: 1. Hydrological phenomena are time series with concealed periodic fluctuations. The results from statistical analysis based upon the current assumption that hydrological phenomena...

This paper attempts to answer the following two questions: (1) Is it possible to derive the law of distribution of hydrological frequency theoretically(2) What type of distribution curve should be adopted as the model of hydrological frequency curve and how to determine their parameters? The results obtained may be summarized as follows: 1. Hydrological phenomena are time series with concealed periodic fluctuations. The results from statistical analysis based upon the current assumption that hydrological phenomena are independent stochastic variables should be accepted with due considerations. 2. In view of the regional nature of hydrological phenomena, the current parctice of analyzing samples taking from a single station only is, in effect, to narrow the sampling field arbitrarily from a larger area to a point, thus reducing the accuracy of the statistical results. Hence, the synthetic utilization of the data of all stations within the hydrologically homo- geneous region is an important measure to increase the accuracy of statistical analysis. 3. The belief that the flood frequency obeys the binomial theorem or Poisson's theorem is but to mix up the priori with the empirical probability problem. The binomial theorem, being a powerful weapon to deal with the problems of priori probability, has not been adquately and properly utilized in the hydrologieal frequency analysis. 4. Analyses have been made of the nature of distribution of shydrologieal series on the basis of Kaptyen's derivation of the skew distribution, which indicate: (1) That the theoretical interpretation of the log-probability law of the hydrologic phenomena by V. T. Chow is not sound; (2) that hydrologic phenomena being results of very complicated meteorological and hydrological processes, it is impossible to derive theoretically the law of distribution for the hydrological series. 5. The view that the flood frequency obeys the Gumbel's distribution is theoretically not sound and also not verified by actual data. 6. According to the nature of the mathematical treatments applied, the method of description of the empirical probability can be classified into three systems: (1) The methods of the generalization of the characteristic factors of the distributions, such as Pearson's curves, Goodrich's curves, etc.; (2) The methods of the modification of a fundamental distribution by series and polynomials, such as Gram-Charlier curves. curves, etc.; (3) The methods of transformed functions, such as the log-probability law, curves, etc. It should be remarked that not only Pearson's and Goodrich's curves are frequency curves of empirical nature, but even the theoretical laws, such as the normal law and the log-probability law, will be aceepted as curves of empirical nature, when used as models for empirical probability problem. 7. Hydrological frequency analysis should not be mystified and made absolute. Instead of free selections, the models of hydrological frequency curve should be uniquely selected and specified. Statistical parameters should be determined not solely by the short period data of single station, but also by the synthetic utilization of the data of possible more stations. 8. It is recommended that one of the two types of distribution, i.e. the log-normal frequency curve with both sides limited and the Pearson's type Ⅲ curve, may be selected as unified models. The author suggests that the K-value corresponding to recurrence intervals of say 10~4, 10~5, or 10~6 years may be selected as the upper and lower limits for the log-normal curve. For Pearson's type III curves, C_s should be treated not as independent but as dependent variables of C_v. 9. The proper way to select and determine the model frequency curve is to see whether it fits well with the actual data of grouped stations (stations to be grouped by regions for rainfall data and by C_v for runoff data) and the reasonableness of the extrapolating part. 10. Suggestions on the method of determination of x and C_v: For point rainfall, iso-x map may be utilized, and the mean C_v for each hydrologicregion may be adopted in order to minimize the errors from single stations and to avoid the discrepancies in results obtained from the same region. With regard to flood frequency analysis, flood mark reconnaissance must be utilized to determine the magnitude and the recurrence interval of the unusual flood. The x and C_v values of the floods and runoffs of hydrologically similiar river basins may be compared. Besides, the reasonableness of the results of frequency calculations as well as of the statistical parameters adopted therein may be checked by comparing runoffs and point-rainfall values of the same frequency.

In this paper a method is proposed for the construction of the D-decompositioncurve for an element or a part of a linear control system to determine its stability. Forvarious frequency responses of the element or part, the relative number of roots of thecharacteristic equation with a negative real part can be determined by this method.Methods of using the D-decomposition curves to judge whether all the roots of the charac-teristic equation possess a negative real part are also discussed. It is illustrated in...

In this paper a method is proposed for the construction of the D-decompositioncurve for an element or a part of a linear control system to determine its stability. Forvarious frequency responses of the element or part, the relative number of roots of thecharacteristic equation with a negative real part can be determined by this method.Methods of using the D-decomposition curves to judge whether all the roots of the charac-teristic equation possess a negative real part are also discussed. It is illustrated in thelast part of the paper that the proposed method can sometimes be employed together withthe describing function method to solve the stability problem of a system with single-valued, nonlinear elements.