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When intelligent fuse is detecting target acoustic signal, affected by external interference and other factors, the signal may bring on trend term. Existence of trend term may cause direct influence on the accuracy of target acoustic signal, so that it should be removed. In allusion to the problems in existing trend term removal methods, such as trend term type should be assumed in advance, and the...
Rotating parabolic reflector antenna combined with parachute is designed to have a parachute-type high power EMP radiator. With EM array complementary radiation as the design idea, a four-feed-arm parachute-type reflector antenna structure with higher feeding efficiency is proposed, thus to strengthen the low-frequency radiating capacity, widen the bandwidth of antenna and improve the radiant efficiency...
For the need of pulse modulation, an electrode of gas switch whose front shape is annular, is introduced. The fundamental principle that how static electric field around electrode is analyzed by finite element is described. The electrodes whose front shapes are hemisphere, annular and flat with inverted round horn are numerical simulated. These three electrodes' advantage and disadvantage are analyzed...
The radioactive field emitted by a small-size electromagnetic pulse (EMP) simulator is studied. Simulation model is built on the basis of FDTD algorithm. The loads of CUSO4 solution, excitation source and absorbing boundary condition are illustrated and analyzed respectively. A new absorbing boundary condition method named convolutional perfectly matched layer (CPML) is introduced. Both the CPML and...
A small-size acceleration measurement system based on ARM is designed and developed in this paper. It adopts Micro-machined capacitive integrated chip Model1221 as sensor and SD card as Data memory. Combined with communication port, application software is designed to display, store and deal with the data measured. By measuring the centripetal acceleration of rotating body at a uniform velocity, the...
Electromagnetic shielding is the technique that reduces and prevents coupling of undesired radiated electromagnetic energy into equipment, so as to enable it to operate compatibly in its electromagnetic environment. Usually, the frequency considered for electromagnetic shielding design is above 10 kHz, but the lower frequency for some special demand is 50 Hz or even 0.01 Hz sometimes. This paper mainly...
According to the characteristic of short-wave frequency-hopped (FH) communication, an OFDM/FH system based on iterative demodulation and decoding is proposed. By combining the advantage of NSD technique and iterative demodulation and decoding, the method could compensate the SNR loss caused by differential modulation and improve the reliability of short-wave communication and improve the system reliability...
This paper presents the measurements of shielding effectiveness of reinforcing bar loops (RBL) and reinforcing bar cage (RBC) to magnetic field. A testing method was applied to measure the shielding effectiveness of RBL and RBC with its joints wired or welded. The signals in this experiment are continuous wave with frequency of 14 kHz, 100 kHz and 200 kHz. The variation of the shielding effectiveness...
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