A Broad-Band Study of Attenuation in Ocean Bottom Sediments
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Reproduced waveform with thin film magnetic heads, distortions (wiggles) of reproduced waveform are sometimes observed. In this study, a method for extracting wiggles from reproduced waveform was devised, and wiggle behavior was studied. Extracted wiggles were in pulse width from 40 to 80 ns, in amplitude from 10 to 30μV, and their locations during reproduced waveform were shifted by and external magnetic field, but wiggle width and amplitude were not affected. After write operation, wiggle pulse width and amplitude changed; however, the area under the extracted pulse was verified constant. Peakshifts of reproduced waveform increased when wiggles came close to the peak of the reproduced waveform, and wiggle amplitude increased.
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P262 Effects of Strain Amplitude on Relaxation Spectra of Wave Attenuation in Rock E.I. Mashinskii* (Institute of Petroleum Geology and Geophysics RAS) SUMMARY The laboratory study of wave attenuation in sandstone and the “atomic” elastic solid states (quartz and duralumin) under confining pressure of 20MPa has been performed using the reflection method on pulse frequency of 1 MHz in the strain amplitude range ~ (0.3 - 2.0) * 10-6. The experiments have shown the unusual results in the behavior of the relaxation spectra of wave attenuation in dependence on strain amplitude. The attenuation nonlinearly decreases with increasing strain amplitude. In
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Accuracy of waveform aware delay calculation approaches in STA tools require selection of an appropriate driver waveform during library characterization. The optimal waveform shape is dependent on process corner, voltage, temperature, parasitics and also the properties of the transistors involved. Traditionally used ramp waveform is not suitable for accuracy particularly at lower voltages and temperatures. Identification of waveform shape across a wide range of operating corners and for different transistor types can involve significant cost in terms of resources and time. This paper discusses an efficient approach for finding the driver waveform for library characterization. It also enlists the factors that influence the waveform shape and the related careabouts during the waveform identification process. Lastly, it proposes an approach to reduce the run-time and resources used to get the optimal characterization waveform at all operating corners.
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A simple artificial neural network is considered for real-time estimation of excess atmospheric attenuation on a satellite communication link with known attenuation at two frequencies. All atmospheric contributors to attenuation are considered except for gases. The network has a two-layer feed-forward structure with 32 neurons in the hidden layer. Its performance is evaluated by computer simulation using 447 hours of measured attenuation data at 20, 40, and 50 GHz. Estimated attenuation tracks well the measured attenuation at 50 GHz. Estimation error standard deviation is 0.36 dB. RMS error is a function of attenuation: it increases slowly with attenuation, but the ratio of error to attenuation decreases with increasing attenuation. This approach accurately estimates excess attenuation without requiring assumptions, but required training data. (4 pages)
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The biphasic waveform has greater defibrillation efficacy than the monophasic waveform. Yet, the optimal type of biphasic defibrillation waveform is still unknown. Our objective was to compare the defibrillation efficacy of three morphologically different biphasic waveforms (named as truncated exponential waveform, modified Zoll waveform, and Gurvich waveform) in an isolated Langendorff perfused rabbit heart. Optical potential mapping techniques were used. The result showed that the Gurvich waveform has the lowest defibrillation threshold (DFT). A multiple comparison test showed that there is a significant difference of DFTs between the modified Zoll waveform and Gurvich waveform (mean/spl plusmn/SE: 0.31/spl plusmn/0.03 J and 0.25/spl plusmn/0.02 J, p<0.02). We also examined the change of membrane potential caused by shocks. The result showed an homogeneous response for different waveforms.
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Abstract The terahertz band characteristic attenuation rate in 6G mobile communication system is studied. Through the model building and simulation, the results show that 6G radio wave fluctuates greatly with the increase of frequency in dry air, and there are multiple peaks. The characteristic attenuation rate of radio wave in water vapor at low frequency band is smaller than that in dry air, and adverse at high frequency band. The results also show that the characteristic attenuation rate increases with the increasement of rainfall, and is faster than that of frequency. The characteristic attenuation rate has little effect on the visibility. For frequency above 150GHz, the characteristic attenuation rate is greatly affected by snowfall intensity, while the frequency below 150GHz is relatively less affected by snowfall intensity. Under the frequency band of 20GHz, the characteristic attenuation rate increases obviously with the increase of frequency, and the characteristic attenuation rate is relatively gentle with the increase of frequency when it is above 20GHz. Meanwhile, the change is not obvious with the water content in the dust. For a certain water content, frequency from 0 to 350 GHz and temperature from 0 to 60 °C, the characteristic attenuation rate mainly increases with the increase of frequency, almost does not change with temperature.
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Frequency scaling concerns the variation of propagation effects with respect to frequency. The objective is to find the relationship between attenuation at a given frequency from the attenuation measured at another frequency, generally lower. Two different kinds of frequency scaling model, corresponding to different interests, can be considered: Long term frequency scaling, describes the relationship between attenuation for the same probability level. It allows studying the design of system operating at high frequency bands (Ka or V band) from the performances of existing systems operating at lower frequency band (Ku-band). Short term frequency scaling or instantaneous frequency scaling (IFS), describes the relationship between simultaneous attenuation at different frequencies. It allows performing uplink power control, where the attenuation on the uplink is estimated from the attenuation measured on the downlink. The different contributions: rains, gas, clouds, which contribute to the total attenuation, depend on frequency in different ways, that's why this technique is most satisfactory when one cause predominates. The present study focus on IFS of rain, the aim is to deduce the attenuation due to rain for one frequency (higher than 40 GHz) from the measurements at another lowers frequencies (Ka Band).
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First, the relation between MFM output and head output waveforms from perpendicular magnetic printed media was clarified. Next, the MFM output waveforms from magnetically printed and head-recorded media were compared by using metal-evaporated (ME) tape as a slave medium. The MFM output waveform corresponds very closely with the head output waveform, and it appears that the MFM output is similar to the perpendicular component of the stray field. In the case of a long bit length, the bit-printing (BP) waveform is similar to the head-recording (HR) waveform, while the edge-printing (EP) waveform is significantly different from the HR waveform. On the other hand, in the case of a short bit length, the BP, EP, and HR waveforms are all sinusoidal, but the phase of the EP waveform is 90° shifted from the HR waveform, while the BP waveform is almost identical to the HR waveform.
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