27 Februari 2011

the super-cool assignment

jadi. sebelum gw berpetualang. gw mesti menyelesaikan satu tugas tergaul sedunia: ngerangkum paper! bukan paper sembarang paper. paper-nya bahasa inggris. ulangi. ba-ha-sa ing-ge-riss. dan ngerangkumnya juga mesti pake bahasa inggris. kurang gaul apa cobaaaaaaaak?

supaya blog gw lebih berwarna dan lebih berguna bagi nusa dan bangsa, bagaimana jika saya taro tugas saya di sini? ada yang protes? *meminjam kata" aryo jaman baheula

yuk, ditilik, mariii.


Monitoring Sediment Concentration with Acoustic Backscattering Instrument
Summarized by: Gabriella Alodia – 15108018

Keywords: water column sediment, backscattering strength, sensitivity model

Hydro-acoustics never work alone. Every single measurement has to be completed with other type of measurements. In this case, the objective of this measurement is to identify the sediment quantity and type in the water column with Acoustic Doppler Current Meter. The identification requires the backscattering strength data, which also known as the signal amplitude.
The signal amplitude data must be calibrated in three steps: unit conversion, range normalization, and instrument normalization. In the first step, the echo amplitude will be processed in a linearization, so that values outside the linear range would not be used for sediment analyses. Then in the second step, the echo level will be normalized by considering the acoustic spreading, water absorption, and particle attenuation. The last step should be avoided because it requires complete characterization of the transmit-and-receive circuit of the instrument, while none of the Doppler systems have been designed with absolute calibration. The product of these calibration calculations is the Volume Scattering Strength (Sv).
In practical applications, usually the three-steps-calibration could be ignored. There are two simpler choices of calibration. The choices are, to do the range normalization only, or to use a calibrated target like a steel ball, so the signal amplitude will be calibrated due to the measurement of the steel ball.
The result of this measurement is a model of Sensitivity due to the (k*a), where (k) is the acoustic wave number and (a) is the particle radius, presented in a table and linear graphic. This Sensitivity defined as the Volume Scattering Strength for a given concentration. This model is useful for predicting what type of sediments that will be detected and also for analyzing acoustic data.

Source: Sediment concentration with acoustic backscattering instruments/Nortek technical notes/October 15, 2001/Document No. N4000-712; Made by: Atle Lohrmann; Controlled by: Ketil Horn

yeaaaaahs. sampai kita berjumpalitaaaaaan.

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