In this article, after reviewing of the INVERSE source and INVERSE SCATTERING problems, two quantetive and qualitative (a new method) of solving the INVERSE SCATTERING problem using reconstructed induction currents are studied.

In the first part of the present paper, a numerical method called spectral finite element method (SFEM) is presented. As shown there, SFEM offered a promising performance in simulating wave SCATTERING phenomena in plates, with less computational effort while obtaining the highest resolution. The forward solution of wave SCATTERING phenomenon based on the differential waveform of highest resolution plays a crucial role for detection of through-thickness crack in plates, as an INVERSE problem. Therefore, the results of the first part of the paper have been used in the second present part, in which a novel approach in wave SCATTERING based crack detection, according to the concept of Time Delay (Differences) Of Arrival (TDOA) has been presented. In the past decades, TDOA and its related concepts have been applied generally on the problem of localization and pursuing sound sources in robotics, electronics engineering, control engineering, and so on. However, in this study TDOA is employed for crack detection problems for the first time. Introducing TDOA has provided a robust algorithm for crack detection which is highly sensitive to the crack location and size. Using the proposed algorithm, a couple of numerical case studies has been studied, in which the predicted crack location and dimensions are quite encouraging.

Acquiring acceptable image quality in microwave imaging is one of the challenging tasks in this field. This paper aims to investigate and compare the modified level set method (MLSM) with four s tate-of-the-art methods i. e., distorted born iterative method (DBIM), contrast source inversion (CSI) method, linear sampling method (LSM) and multiple signal classification (MUSIC) method in image reconstruction with focus on quantitative comparison. Furthermore, three important criteria of image quality, namely accuracy, resolution and contrast, are quantitatively investigated for the aforementioned methods. The three quantitative methods of DBIM, CSI, and MLSM start with an initial guess of the scatterer profile and change it in an iterative process to get close to the actual scatterer. Despite large numerical computations, the resolution and contrast in these methods are remarkably high compared to the other two methods. As will be seen, the DBI and CSI methods are capable of completely resolving two objects at 0. 4λ and MLSM at 0. 07λ . Also, the MLSM provides more accurate reconstructions than the other two, since the investigation domain is deformed to a smaller one

This paper uses a method for shape reconstruction of a 2-D homogeneous object with arbitrary geometry and known electrical properties. In this method, the object is illuminated by a Gaussian pulse, modulated with sinusoidal carrier plane wave and the time domains’ footprint signal due to object presence is used for the shape reconstruction. A nonlinear feedback loop is used to minimize the difference between the measured and calculated signals obtained, by using FDTD at consecutive time windows. The layers of the objects’ shape are reconstructed while the incident plane wave moves over the objects’ surface. Based on the above method, some results are presented for an object with typical geometry. The effect of modulating carrier frequency was investigated for conductivity and dielectric objects.

Porous silicon (PS) layers come into existence as a result of electrochemical anodization on silicon. Although a great deal of research has been done on the formation and optical properties of this material, the exact mechanism involved is not well-understood yet. In this article, first, the optical properties of silicon and porous silicon are described. Then, previous research and the proposed models about reflection from PS and the origin of its photoluminescence are reviewed. The reflecting and SCATTERING, absorption and transmission of light from this material are then investigated. These experiments include: different methods of PS sample preparation; their photoluminescence, reflecting and SCATTERING of light; determining different characteristics with respect to Si bulk

This study describes a hybrid technique for identification of buried objects. The object’s shape and electromagnetic profile are reconstructed from evaluations of electrical permittivity and conductivity. The method suggests a combination of linear sampling and optimization. Linear sampling method (LSM) is used to recover shape and metaheuristic optimizations essential to reconstruct the inside profile. A special case of a non-homogenous object is considered. In this case the object is a buried homogenous dielectric for which the position and volume of the hole inside is not known. In this case, after recovering data by the same process used in the first step, it is necessary to recover the volume and position of the hole. This case will be useful when the final target of identification is an embedded object. The final results of this case verify the effectiveness and feasibility of the proposed method. Effectiveness of the method is validated by application of one real world cases involving civil engineering. In all cases presented in this study, the rates of final reconstruction error are acceptable and less than 10%. These results prove that this proposed procedure can be applied to reconstruct hollow objects correctly.

Summary Several newly constructed tunnels, which have been damaged by earthquake loading, have led to extensive research on the evaluation of earthquake effects on tunnels. Underground structures are increasingly being built and exploited in the context of urban expansion and development. Tunnels are one of the most important underground structures. Failure of several tunnels under earthquake loading, and especially damage to these tunnels, have been the reasons to investigate the effects of earthquake on the tunnels. Introduction Various activities, especially during earthquake, on the adjacent structures are of particular importance. This importance will be more in the vicinity of the historical building, due to their vast material and spiritual values. In this research, using the Henkel type I and three scale accelerometers related to the earthquakes in Northridge, Tabas and Kobe, and employing the expanded FESCAM program in MATLAB environment, the historical structures of thirty-three buildings have been studied. Methodology and Approaches In this research, nonlinear time histories analysis has been used to generalize Henkel's relationship and to calculate the exact difference. The input waves have been investigated by the researchers for use in the Henkel harmonic waves function. The Henkel function of the first type using the mentioned accelerations is used considering the amount of dissociation, the degree of strain and stress around the twin tunnels as an additive parameter to the limited element analysis of the present study. Results and Conclusions In this paper, the operation of differentiation is expanded with the use of mathematical relations. A case study of twin tunnels is Si-o-se-pol twin tunnels. The results of this study show that the mean displacement of horizontal thirty three bridges there in comparison with the failure to consider the effect of fractionation is increased by 28. 8% and the displacement rate of the thirty three bridges compared to the failure includes the difference of 11 / 30%. Moreover, the displacement of underground structures during an earthquake is less than that of the ground structures. The results of the Mann-Whitney test with the SPSS software program have shown that there is no significant difference between the seismic performance of the thirty three bridges with the effect of tunneling dispersion and without the effect of tunneling dissociation (P-value≥ 0. 05).

Background: Producing the ideal therapeutic electron beams from a clinical linear accelerator (Linac), is crucial to optimize dose delivery in radiotherapy. The aim of this study was to investigate the properties of electron beams with and without the SCATTERING foil. Materials and Methods: Varian Linac 2100CD head was simulated by means of MCNPX-2. 7 program. After validation with measured data, SCATTERING foils were removed and then different dosimetric properties of 6 and 9 MeV electron beams such as depth dose percentage, dose profile, range, surface dose, dose rate and photon contamination were calculated and compared for field sizes ranging from 0. 25×0. 25 to 10×10 cm2 in three states with primary and secondary SCATTERING foil (SF), without primary SCATTERING foil (PSFF) and without primary and secondary SCATTERING foil (SFF). Results: By removing the SCATTERING foils, dose rates and surface doses were increased more than 25 times in 0. 25×0. 25 cm2 field, and in the bigger fields, it was less in 10×10 cm2 field, almost 4 times and the photon contamination is reduced by 20% times in 0. 25×0. 25 cm2 field. Also, Adjacent organs receive a lower dose, Because the dose profile curve was shrieked, it was almost 1cm in field 2×2 cm2 and less than 1cm in other fields. The dose profile flatness was diminished in SCATTERING foil-free (SFF) mode which is not crucial for the small fields. Conclusion: Removing SCATTERING foil improves dosimetric properties of electron beams specially to treat the superficial tumors and for the small field radiotherapy.

In many infeasible linear programs it is important to construct it to a feasible problem with a minimum parameters changing corresponding to a given nonnegative vector. This paper defines a new INVERSE problem, called “INVERSE feasible problem”. For a given infeasible polyhedron and an n-vector x0 a minimum perturbation on the parameters can be applied and then a feasible polyhedron is concluded.