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Asphalt Concrete Pavement and prevention of defects


Off the asphalt, paving the mixture should have experience of meeting someone at the spread of minor fines segregation. And repair other defects. 2.6 rolling roller compacted to have someone command; roller compacted determined by test program rolling shop, roller pressure or less pressure leakage can not occur, the width of roller compacted to sufficient overlap, but not too much rolling; roller speed can not be too fast, rolled to order; roller can not be parked on the asphalt paving is not the cooling layer. 2.7 site to take asphalt testing laboratory will send an experienced hand to take materials; in sub-feed and do extraction, screening, Marshall test experimental operating procedures when operating in strict accordance with: mixing starting materials in the asphalt mixing plant, after send an experienced laboratory assistant to take 1-2 months to do asphalt Marshall test specimens to determine the accuracy of the mix; the best hot day after mixing hopper screening, understanding the aggregate and mixing plant changes and operating conditions; each week pooled analysis of experimental data to understand changes in asphalt mixtures, prepare the response; laboratory will send an experienced hand to the paving site at any time check the situation asphalt paving : core drill core sampling and removal of debris like to carefully to avoid damage caused by the sample. (Continued on page 37) TECHNOLOGY EDUCATION front 0SCIENCE & TECHNOLOGYINFORMATION2008 0 s 32 Figure 1 Simulink model of radar noise FM jamming band-limited white noise generator through the narrow-band digital filter device by Gaussian noise. Then after the noise spectrum obtained by Fourier transform wave approximation, as shown in Figure 2. Figure 2 Frequency spectrum of noise through the oscilloscope Scope1. Amplitude of radar echo signal can be noise amplitude modulation signal and the echo signal with noise superposed compared in Figure 3. (First column for the simulation of radar echo amplitude modulation signal, the second column the noise FM signal, the third column is the noise signal, the fourth column is the superposition of echo and noise after the signal), can be seen from the way, the radar echo signals have been completely submerged in the noise of the FM signal. Figure 3 shows the results of the oscilloscope Scope1 Third, simulation results of the following noise FM jamming on the radar of the role of the receiver. When the interference bandwidth is greater than the receiver bandwidth,[link widoczny dla zalogowanych], called the narrow-band interference. Figure 4 shows the narrow-band interference spectrum. When the interference bandwidth is less than the receiver bandwidth, known as wideband interference. Figure 5 shows the wideband interference spectrum. The simulation can be compared under different conditions clearly observed after the results of demodulation, as shown in Figure 6, can be seen in the narrowband interference conditions, the receiver put the output is approximately constant amplitude, random-width pulse sequences, cover poor performance, when the interference bandwidth is increasing, the random pulse began to overlap, in the noise put out approximately normal distribution, the result is better. Figure 4 The spectrum of narrow-band spectrum and by observing the waveform, wideband interference is better than the narrow-band interference effect that noise FM jamming for blocking broadband interference. Figure 5 The spectrum of broadband can be seen from the above analysis, the use of Simulink technology enables FM signal to noise calculation and analysis become very easy and intuitive. Figure 6 in place under different conditions, the output signal waveform IV Conclusion radar jamming signals in the design process, if the rational use of Simulink technology, can achieve a multiplier effect. Of course, the paper Simulink in the use of radar jamming signal, but only a preliminary attempt, only the continuous exploration, Simulink technology the use of radar jamming signal can reach more in-depth a wide range of applications. 【
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