The dead oil NMR relaxation times are measured with two working frequency (2 MHz and 23 MHz) NMR spectrometers in this paper.

With the study of the current methods of route multi identify in expressway,the problem of how to choose the working frequency in route identify system with RFID is researched.

The results show that noise spectrum of ultrasonic cleaner has a broadband and contains largely high frequency components,and its basic frequency depends on the working frequency of ultrasonic cleaner.

In order to design high performance and reliability linear refrigerator compressors,the factors influencing the natural frequency of the linear compressor were analyzed theoretically,and experimental study on operating characteristics of different discharge pressure and operation frequency were conducted.

In order to increase the operation frequency of a pulse detonation rocket engine(PDRE),a PDRE model with solenoid valve was designed whose diameter and length was 30 mm and 1 000 mm respectively.

The first order analysis of steady state motion for piston component was deduced by using Fourier expansion method,and the amplitude frequency characteristics was presented.

The experiment results indicate that the frequency of eccentricity sensor must be as high as possible under keeping the stability of the sensor, and that using the same sensor probe, the larger the diameter of cable .

According to the fundamental characteristics and the antenna design method of the wireless router,the paper develops a microstrip radiation unit,the operating frequency is in the C and S-band,and tests the parameters of these types of radiation units.