Computational inference
03 Simulation programs to generate artificial array time series data Project Leader
Makio Ishiguro
The microtremor investigation is a geophysical technique to survey the underground structure. From the observation of the phase velocity dispersion of the surface waves (Rayleigh wave) contained in the microtremors(the usual vibration of ground surface) it is possible to estimate physical constant distribution with depth. To investigate the effect of the characters of the incident waves and/or the array configuration on the accuracy of the estimated phase velocities, we made computer simulation programs to generate artificial array time series data. In this program, we assume the phase velocity of waves, the power spectrum of the waves, and the angle of incidence of wave to the array, and make synthetic waveforms by inverse Fourier transformation. We analyze these waves by the frequency-wavenumber spectrum method (F-K method), and compare with the correct values.


Members
Makio Ishiguro

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04 Monte Carlo Combinatorics Project Learder
Yukito Iba
Generation and counting of objects that satisfy given constraints is an important problem in various fields of statistical science, such as experimental design and coding. In the figure, a 3 x 3 "Latin square" is shown as an example, where the numbers 1 to 3 is arranged in a way that no row or column contains the same number twice. When the size of the tables increased to 10 x 10, which satisfy the same constraints, the number of the tables is as large as the number of water molecules in 100000000 tons of water. Extended ensemble Monte Carlo method enables us generation and approximate counting of such complex objects without skillful programming or case by case tricks. The aim of the project is development of new applications of this family of algorithm. 　


Members
Yukito Iba

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A Latin square and its representation as a 0-1 table
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