Microwave imaging from total electric field data

A novel gradient-based inverse scattering method for imaging inhomogeneous objects from time-domain data of only total electric field is presented. Unlike most inverse scattering methods, the proposed method does not require the explicit information of the incident field illuminating a region of interest. Numerical simulations demonstrate the effectiveness of the method.2014 IEEE Antennas and Propagation Society International Symposium, APSURSI 2014; Memphis Convention CenterMemphis; United States; 6 July 2014 through 11 July 201

Application of time reversal to imaging electrical properties of inhomogeneous cylindrical objects

A time-domain inverse scattering approach using time-reversed fields for reconstructing electrical parameters of cylindrical objects has been proposed in a previous work. The approach does not require the explicit knowledge of incident fields illuminating the object. The cost functional represented in terms of the time-reversed fields was minimized by a genetic algorithm (GA). In this paper, we propose a gradient-based minimization for reconstruction of an inhomogeneous object for which GA can not be applied due to computational complexity. The time-reversed fields are calculated by time-reversing the equivalent current sources determined by the total fields recorded on a measurement line. Numerical simulations are carried out to show the effectiveness of the proposed method.8th European Conference on Antennas and Propagation, EuCAP 2014; The Hague; Netherlands; 6 April 2014 through 11 April 201

Experimental Study on Flow and Bank Erosion in Steep and Curved Trapezoidal Channels

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

STUDY FOR ESTIMATION OF AIR-SEA C02 GAS TRANSFER BY WAVE BREAKING MODEL USING SATELLITE DATA — ESTIMATION OF THE FRICTION VELOCITY CONSIDERING WAVE EFFECT

The determination of wind friction velocity from satellite-derived wind data will take an important role of key factors for computation of C02 flux transfer. It is necessary for relation between wind speed and wind friction velocity to determine that of relation between nondimensional roughness length and wave age, included with all parameters (wind, wave). In this study, we proposed a new method to estimate u„, which is based on the new relationship between non-dimensional roughness and wave velocity, after considering fetch and wave directionality. Consequently, we obtained the new relationship between friction velocity and wind speed. Using this relationship, we estimated the wave frequency from two methods: 3 per 2 powers law (Toba, 1972) and WAM model (WAMDI, 1988). The results arc compared with the results estimated from Charnock formula (1955) and the above influence of wave effects on the wind stress is also discussed. A new relationship was established to determine CO. exchange coefficient based on whitecap model (Monahan and Spillane 1984), using U|0-u, relationship in North Pacific Ocean, satellite data of NOAA-AVHRR (SST) and DMSP-SSM-I (wind speed) in Oct., Nov., and Dec. 1991. The C02 exchange coefficient estimated by other models (Wanninkhof, 1992; Liss and Merlivat, 1986; Tans et al., 1990) are also compared with these results. The results show the importance of wave breaking effect. Key words: wind waves, friction velocity, C02 exchange coefficient, roughness length, wave age