There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

https://biblio.ugent.be/publication/685594/file/1130605.pdf

Review of Particle Physics

/pdf/review-of-particle-physics-1996-1997-jeg703df6k.pdf

Review of Particle Physics, 1996-1997

Low-energy phenomenology of superstring-inspired E6 models

In this paper, we examine the role of polarimetry in synthetic aperture radar (SAR) interferometry. We first propose a general formulation for vector wave interferometry that includes conventional scalar interferometry as a special case. Then, we show how polarimetric basis transformations can be introduced into SAR interferometry and applied to form interferograms between all possible linear combinations of polarization states. This allows us to reveal the strong polarization dependency of the interferometric coherence. We then solve the coherence optimization problem involving maximization of interferometric coherence and formulate a new coherent decomposition for polarimetric SAR interferometry that allows the separation of the effective phase centers of different scattering mechanisms. A simplified stochastic scattering model for an elevated forest canopy is introduced to demonstrate the effectiveness of the proposed algorithms. In this way, we demonstrate the importance of wave polarization for the physical interpretation of SAR interferograms. We investigate the potential of polarimetric SAR interferometry using results from the evaluation of fully polarimetric interferometric shuttle imaging radar (SIR)-C/X-SAR data collected during October 8-9, 1994, over the SE Baikal Lake Selenga delta region of Buriatia, Southeast Siberia, Russia.

Polarimetric SAR interferometry

SAR Interferometry is a common methodology for detection of Natural disaster affected area. However, we applied radar polarimetric analysis to ALOS/PALSRA data sets to investigate the possibility of detection of Tsunami affected area only from the SAR data acquired after the event. The resolution of the SAR image is 30m by 30m and cannot identify each house or buildings in the area. However, we have demonstrated that single-bonce and double-bounce scattering mechanism clearly shows the Tsunami affected area in Ishinomaki city, Japan, after the Great East Japan Earthquake and Tsunami. We could also showed that the standard deviation of the polarimetric orientation angle increases by the damage, and can be used for the measure of the damage.

Determination of Tsunami-affected areas by polarimetric SAR

A borehole radar is one form of ground penetrating radars, which operates in a borehole. The significant feature of a borehole radar is its accessibility to targets. Most conventional borehole radar use dipole antennas, which are omnidirectional. However, in many engineering applications, the three-dimensional positions of targets such as fractures and pipes should be accurately determined. We have designed and constructed a prototype broadband directional borehole radar system. The receiver is a conformal array antenna. This radar system operates between 100 and 300 MHz. Since the space available for the array and frequency bandwidth are limited, a super resolution technique should be applied. This paper presents a method for three-dimensional position estimation of coherent broadband sources with the conformal array in a borehole. This method is based on the MUSIC algorithm, and the problem formulation and a decorrelation algorithm are shown. Also, we show experimental results to verify the presented algorithm.

Estimation of three-dimensional coherent source positions with a directional borehole radar by MUSIC algorithm

Raytracing is an approximate method which is very rapid and efficient in wave field calculation. Accurate and efficient traveltime and raypath calculation is essential for successful application of a number of near-surface imaging techniques. The grid raytracing method has incorporated two important developments in recent traveltime modeling research, that is, fast wave-front tracking and wave-front construction. So the method is more efficient than previous wave-front construction methods and more accurate than the fast marching methods in describing traveltimes and raypaths. On the basis of the grid raytracing method, this paper has improved the algorithms of the traveltime calculation. By calculations and comparisons, the modified algorithm has proven to improve the efficiency of the grid raytracing method.

A Modified grid raytracing method

Fundamental Study of Borehole radar to evaluate a subsurface structure

We propose an algorithm to estimate moisture level of active layer of permafrost over permafrost area. This algorithm is based on Oh's semi-empirical model, and PALSAR data observed both in winter and summer seasons with vh polarization. PALSAR vh polarization data observed in winter is used to estimate surface roughness of permafrost. Then, the estimated surface roughness and PALSAR vh polarization data observed in summer is used to estimate the moisture level of the active layer of the permafrost. The moisture levels estimated from PALSAR data moderately matched to those of validation data taken in the field with correction factor of 0.6, while the surface roughness value shows some difference. The possible cause of the difference observed in the roughness value is that the surface roughness derived from the field data collection represents the roughness of the top of the sphagnum moss layer covered on the active layer of the permafrost, while the one estimated from PALSAR represents the roughness of the underlying active layer of the permafrost.

Motoyuki Sato

Papers

Determination of Tsunami-affected areas by polarimetric SAR

Estimation of three-dimensional coherent source positions with a directional borehole radar by MUSIC algorithm

A Modified grid raytracing method

Fundamental Study of Borehole radar to evaluate a subsurface structure

Moisture & Roughness map in arctic national wildlife Refuge/Alaska