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This paper presents a antenna array pattern synthesis technique based on trust region unconstraint method. An attractive property of these methods lies in their numerical stability and robustness. The Hessian matrix is necessary for traditional trust region algorithms, it lead to very heavy computational load when the number of array elements is very lager. Using Broyden -- Fletcher -- Goldfarb --...
Accurately reconstruct the tumor target in an acoustic heterogeneous tissue is a hot research issue in thermo-acoustic tomography (TAT). In this paper, we present three imaging algorithms for microwave induced thermo-acoustic tomography (MITAT): time reversal mirror (TRM), active adjoint modeling (AAM) method and iterative reconstruction method (IRM). The performance of the three imaging methods for...
In this paper, a new method for accurately picking the time-of-flights (TOFs) of tumor is proposed in microwave induced thermo-acoustic tomography (MITAT) system. The proposed method makes use of the properties of induced thermal acoustic signal and combines them with the wavelet transform and Akaike information criterion (AIC). Both numerical simulations and ex vivo experimental results are given...
For subsurface sensing objects using electromagnetic waves, most of current imaging methods need priori information of exact dielectric properties of background media in order to accurately reconstruct the concealed targets. This condition is hardly satisfied in practice. Recently, an efficiently qualitative imaging method termed electromagnetic inverse scattering series method (EISSM) is developed...
The performance of synthesis pattern with sparse arrays is known to degrade in the presence of errors in the array manifolds. This paper introduces a beampattern synthesis approach with uncertain manifold vectors perturbation for linear array. In order to match the desired pattern and minimize the elements simultaneously, the convex optimization of minimizing a reweighted l1-norm objective based on...
To reconstruct objects buried in layered media, most of current imaging methods are based on a common assumption that the dielectric properties of layered media are given. However, this assumption is unrealistic in practice. To study a more realistic electromagnetic inverse scattering problem in which the dielectric properties of layered media are not given, an inverse scattering series (ISS) method...
In this paper a Xenon-lamp-pumped four rods pulsed Nd:YAG laser is presented. The influence of offset angle of Nd:YAG rods and thermal stable regions in the resonator have been analyzed theoretically, and tolerance of offset angle and is given. A plane-plane symmetrical resonator has been used in the experiment, and the distance between two neighbor rods is two times of that between the mirrors and...
The impermeability of rock mass is one of important indexes to evaluate the rock foundation of hydraulic structure and underground-water caverns, which have direct relation to rock quality and necessity to take impermeable measure. The paper build the indexes system of evaluating rock impermeability that taking the dam rock mass of Gauanyinyan Hydropower Station as an example, extension assessment...
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