A New Discrete Frequency Spectrum Correction Method For Extremely High Frequency Signal

2018 ◽  
Author(s):  
Mao Yuwen ◽  
Yang Dongyu ◽  
Li Ming ◽  
Xie Changhua
Keyword(s):  
Frequency Spectrum ◽  
High Frequency ◽  
Correction Method ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Discrete Frequency ◽  
Extremely High Frequency ◽  
Spectrum Correction

Experimental Study of Partial Discharge UHF Detection in Transformer Oil

2013 ◽  
Vol 437 ◽  
pp. 341-345
Author(s):  
Yao Feng ◽  
Fu Jiang Mo ◽  
Zhang Jian
Keyword(s):  
Frequency Spectrum ◽  
High Frequency ◽  
Partial Discharge ◽  
Transformer Oil ◽  
Radiation Characteristics ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Line Radiation ◽  
Attenuation Characteristics ◽  
Oscillation Characteristics

This paper studies the characteristic frequency of partial discharge in transformer oil [, and with the spectrum characteristics of partial discharge in air was measured by the comparison of uhf signal inside the metal tank and the attenuation characteristics and metal wire in the air on the radiation characteristics of uhf signals. The results show that the frequency spectrum of the partial discharge in transformer oil is higher than the frequency spectrum of the partial discharge in air. Ultra high frequency signal have the oscillation characteristics in the metal box body propagation. The transformer has the certain ability of outgoing line radiation of partial discharge signal inside.

Dither in a rolling airframe flight vehicle with a two-position actuator: An amplitude distribution approach

2016 ◽  
Vol 39 (8) ◽  
pp. 1205-1215 ◽  
Author(s):  
Bahram Mohammadi ◽  
Mohammad Reza Arvan ◽  
Yousof Koohmaskan
Keyword(s):  
High Frequency ◽  
Degrees Of Freedom ◽  
Coupling Effect ◽  
Cross Coupling ◽  
Amplitude Distribution ◽  
Feedback System ◽  
Flight Vehicle ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Minimal Error

Rolling airframe manoeuvring is a type of manoeuvre in which the missile provides continuous roll during flight. Cross-coupling between the angle of attack and sideslip in rolling airframe missiles (RAMs) yields a coning motion around the flight path. As the pitch and yaw cross-coupling effect decreases, the radius of this coning motion decreases and the accuracy of the control system increases. Two-position (on–off) actuators are used in most RAMs. The presence of a two-position actuator in a feedback system makes its characteristics non-linear. A high-frequency signal so-called dither is applied to compensate for the non-linearity effect of the actuator characteristic in the feedback system and to stabilize the coning motion. The amplitude distribution function (ADF) method in dither analysis shows that the smoothed non-linearity characteristic can be computed as the convolution of the original non-linearity and the ADF of the dither signal. According to the four-degrees-of-freedom (4-DOF) equations of RAMs in a non-rolling frame and regarding various dither signals through the ADF approach on a two-position actuator, an analytical condition for dither amplitude in coning motion stability of RAMs is derived. It was shown that the triangular signal with specified amplitude and high enough frequency led to a smoother response of two-position actuators. Finally, by applying beam-riding guidance to a RAM, the performance of dithers for decreasing the distance of the missile from the centre of the beam is validated through simulations. It is illustrated that applying the triangular dither resulted in minimal error.

scholarly journals An Investigation into Error Source Identification of Machine Tools Based on Time-Frequency Feature Extraction

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Dongju Chen ◽  
Shuai Zhou ◽  
Lihua Dong ◽  
Jinwei Fan
Keyword(s):  
Machine Tool ◽  
Frequency Domain ◽  
Surface Topography ◽  
High Frequency ◽  
Low Frequency ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Time Frequency ◽  
Cross Correlation Analysis ◽  
Correlation Analysis Method

This paper presents a new identification method to identify the main errors of the machine tool in time-frequency domain. The low- and high-frequency signals of the workpiece surface are decomposed based on the Daubechies wavelet transform. With power spectral density analysis, the main features of the high-frequency signal corresponding to the imbalance of the spindle system are extracted from the surface topography of the workpiece in the frequency domain. With the cross-correlation analysis method, the relationship between the guideway error of the machine tool and the low-frequency signal of the surface topography is calculated in the time domain.

Magnet Temperature Estimation in Surface PM Machines Using High-Frequency Signal Injection

2010 ◽  
Vol 46 (4) ◽  
pp. 1468-1475 ◽  
Author(s):  
David Díaz Reigosa ◽  
Fernando Briz ◽  
Pablo García ◽  
Juan Manuel Guerrero ◽  
Michael W Degner
Keyword(s):  
High Frequency ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Temperature Estimation ◽  
Signal Injection
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