Impact of directional illumination control parameters on seismic signals
To improve quality of seismic signals, DICT (directional illumination control technique) of DVAS (the distributed vibrator array system) is developed. It explains DICT theory in seismic wave domain and states why DVAS can generate directional seismic wave with DICT. The property of directional seismic wave can be described with directional factor. From directional factor, some control parameters such as amount of vibrators, arrangement of DVAS and delay time play an important role in seismic wave directivity and reflected waves' SNR (signal signal-to-noise ratio). To study parameters of directional illumination system, receiving signals are simulated by numerical method. The results show that reflected wave' SNR can be improved with more vibrators and small space between adjacent source in the same line. When the amount and space of source are settled down, a long delay time can increase reflected wave' SNR in shallow lays and a short delay time can boost signal SNR in deep lays. It concludes that DICT is a better control method to achieve high SNR signals with proper parameters. Furthermore, it offers some rules on how to determine parameters.
A beam-forming transmit ASIC for driving ultrasonic arrays
This paper describes the design of a programmable eight-channel application specific integrated circuit (ASIC) for driving ultrasonic array transducers. The ASIC is capable of generating variable delay lengths of up to 65 μs in steps of 1 ns. Integrated on the same chip is an array of eight high-voltage pulser circuits (up to 100 V). The output pulse width can also be set to match the transducer operating frequency. A minimum width of 20 ns is possible and the rise and fall times are typically 5 and 7 ns. It can also be programmed to give bursts of up to 16 repetitions to facilitate Doppler imaging.
The Law of Failure
If a broker-dealer liquidates in federal bankruptcy court, why does an insurance company liquidate in state court, and a bank outside of court altogether? Why do some businesses re-organize under state law 'assignments', rather than the more well-known Chapter 11 of the Bankruptcy Code? Why do some laws use the language of bankruptcy but without advancing policy goals of the Bankruptcy Code? In this illuminating work, Stephen J. Lubben tackles these questions and many others related to the collective law of business insolvency in the United States. In the first book of its kind, Lubben notes the broad similarities between the many insolvency systems in the United States while describing the fundamental differences lurking therein. By considering the whole sweep of these laws - running the gamut from Chapter 11 to obscure receivership provisions of the National Bank Act - readers will acquire a fundamental understanding of the 'law of failure'.