Inverse Scattering of Two-Dimensional Objects Using Linear Sampling Method and Adjoint Sensitivity Analysis

Eskandari, Ahmadreza,Eskandari, Mohammad Reza The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

This paper describes a technique for complete identification of a two-dimensional scattering object and multiple objects immersed in air using microwaves where the scatterers are assumed to be a homogenous dielectric medium. The employed technique consists of initially retrieving the shape and position of the scattering object using a linear sampling method and then determining the electric permittivity and conductivity of the scatterer using adjoint sensitivity analysis. Incident waves are assumed to be TM (Transverse Magnetic) plane waves. This inversion algorithm results in high computational speed and efficiency, and it can be generalized for any scatterer structure. Also, this method is robust with respect to noise. The numerical results clearly show that this hybrid approach provides accurate reconstructions of various objects.

Inverse Scattering of Two-Dimensional Objects Using Linear Sampling Method and Adjoint Sensitivity Analysis

Ahmadreza Eskandari,Mohammad Reza Eskandari 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

This paper describes a technique for complete identification of a two-dimensional scattering object and multiple objects immersed in air using microwaves where the scatterers are assumed to be a homogenous dielectric medium. The employed technique consists of initially retrieving the shape and position of the scattering object using a linear sampling method and then determining the electric permittivity and conductivity of the scatterer using adjoint sensitivity analysis. Incident waves are assumed to be TM (Transverse Magnetic) plane waves. This inversion algorithm results in high computational speed and efficiency, and it can be generalized for any scatterer structure. Also, this method is robust with respect to noise. The numerical results clearly show that this hybrid approach provides accurate reconstructions of various objects.

The impact of EPB pressure on surface settlement and face displacement in intersection of triple tunnels at Mashhad metro

Eskandari, Fatemeh,Goharrizi, Kamran Goshtasbi,Hooti, Amir Techno-Press 2018 Geomechanics & engineering Vol.15 No.2

The growth of cities requires the construction of new tunnels close to the existing ones. Prediction and control of ground movement around the tunnel are important especially in urban area. The ground respond due to EPB (Earth Pressure Balance) pressure are investigated using the finite element method by ABAQUS in intersection of the triplet tunnels (Line 2, 3 and 4) of Mashhad Urban Railway in Iran. Special attention is paid to the effect of EPB pressure on the tunnel face displacement. The results of the analysis show that in EPB tunneling, surface settlement and face displacement is related to EPB pressure. Moreover, it is found that tunnel construction sequence is a great effect in face displacement value. For this study, this value in Line 4 where is excavated after line 3, is smaller than that line. In addition, the trend of the displacement curves are changed with the depth for all lines where is located in above and below, close to and above the centerline tunnel face for Line 2, 3 and 4, respectively. It is concluded that: (i) the surface settlement decreases with increasing EPB pressure on the tunnel face; (ii) at a constant EPB pressure, the tunnel face displacement values increase with depth. In addition, this is depended on the tunneling sequence; (iii) the trend of the displacement curves change with the depth.

Highly Selective and Simple Zero and First Order Derivative Spectrophotometric Determination of Palladium by Using α-Benzilmonoxime in Triton X-100 Micellar Solution

Eskandari, Habibollah,Karkaragh, Gholamhassan Imanzadeh Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.12

The reaction of ${\alpha}$-Benzilmonoxime with palladium(II) produces a green complex in triton X-100 micellar media. Palladium has been determined using zero and first derivative spectrophotometric methods. The absorbances of Pd(II)- ${\alpha}$--benzilmonoxime complex at 441.8 and 677.0 nm in 0.10 M perchloric acid solution were monitored and linear working ranges of 0.3-12.0 and 0.7-20 ${\mu}$g mL$^{-1}$ with detection limits of 0.07 and 0.10 ${\mu}$g $mL^-1$ were obtained, respectively. Also, recoveries in the range of 92.8 to 100.1% and relative standard deviations in the range of 0.4 to 7.1% were obtained. First derivative spectrophotometry has also been applied for palladium determination under the optimum condition. The linear dynamic range of 0.2-24.0 ${\mu}$g $mL^{-1}$ palladium with relative standard deviations of 0.6-6.9% and recoveries in the range of 94.9-102.5% has been obtained by first derivative spectrophotometry. The method shows high selectivity because of the high concentration of acid used, which prevents formation of complexes of ${\alpha}$--benzilmonoxime with the other cations. The palladium complex formed was stable at least one day. The method was successfully applied to the determination of palladium in some synthetic palladium alloys and palladium-charcoal powder.

Coating gold nanoparticles to a glass substrate by spin-coat method as a surface-enhanced raman spectroscopy (SERS) plasmonic sensor to detect molecular vibrations of bisphenol-a (BPA)

Eskandari, Vahid,Hadi, Amin,Sahbafar, Hossein Techno-Press 2022 Advances in nano research Vol.13 No.5

Bisphenol A (BPA) is one of the chemicals used in monomer epoxy resins and polycarbonate plastics. The surface-enhanced Raman spectroscopy (SERS) method is precise for identifying biological materials and chemicals at considerably low concentrations. In the present article, the substrates coated with gold nanoparticles have been studied to identify BPA and control the diseases caused by this chemical. Gold nanoparticles were made by a simple chemical method and by applying gold salt and trisodium citrate dihydrate reductant and were coated on glass substrates by a spin-coat approach. Finally, using these SERS substrates as plasmonic sensors and Raman spectroscopy, the Raman signal enhancement of molecular vibrations of BPA was investigated. Then, the molecular vibrations of BPA in some consumer goods were identified by applying SERS substrates as plasmonic sensors and Raman spectroscopy. The fabricated gold nanoparticles are spherical and quasi-spherical nanoparticles that confirm the formation of gold nanoparticles by observing the plasmon resonance peak at 517 nm. Active SERS substrates have been coated with nanoparticles, which improve the Raman signal. The enhancement of the Raman signal is due to the resonance of the surface plasmons of the nanoparticles. Active SERS substrates, gold nanoparticles deposited on a glass substrate, were fabricated for the detection of BPA; a detection limit of 10-9 M and a relative standard deviation (RSD) equal to 4.17% were obtained for ten repeated measurements in the concentration of 10-9 M. Hence, the Raman results indicate that the active SERS substrates, gold nanoparticles for the detection of BPA along with the developed methods, show promising results for SERS-based studies and can lead to the development of microsensors. In Raman spectroscopy, SERS active substrate coated with gold nanoparticles are of interest, which is larger than gold particles due to the resonance of the surface plasmons of gold nanoparticles and the scattering of light from gold particles since the Raman signal amplifies the molecular vibrations of BPA. By decreasing the concentration of BPA deposited on the active SERS substrates, the Raman signal is also weakened due to the reduction of molecular vibrations. By increasing the surface roughness of the active SERS substrates, the Raman signal can be enhanced due to increased light scattering from rough centers, which are the same as the larger particles created throughout the deposition by the spin-coat method, and as a result, they enhance the signal by increasing the scattering of light. Then, the molecular vibrations of BPA were identified in some consumer goods by SERS substrates as plasmonic sensors and Raman spectroscopy.

Highly Selective Derivative Spectrophotometry for Determination of Nickel Using 1-(2-Pyridylazo)-2-naphthol in Tween 80 Micellar Solutions

Eskandari, Habibollah Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.8

A spectrophotometric and first derivative spectrophotometric method was developed in aquatic Tween 80 micellar solutions for selective determination of nickel without using any pre-separation step. 1-(2-Pyridylazo)-2-naphthol (PAN), as a sensitive chromogenic complexing agent formed a red-colored Ni(II)-PAN complex in Tween 80 media with satisfactory solubility and stability. Conditions such as pH, PAN concentration, type and concentration of micellizing agent were optimized. Molar absorptivity of Ni-PAN complex was found $4.62\;{\times}\;10^4L\;cm^{?1}\;mol^{?1}$ at 569 nm, under the optimum condition. Calibration graphs were derived by zero, first and second derivative spectrophotometry at maximum wavelengths of 569, 578 and 571 nm with linear ranges of 30-1800, 20-2500 and 30-2000 ng $mL^{?1}$ , respectively. Precision as standard deviation as well as accuracy as recovery percent were in the range of 1-20 ng $mL^{?1}$, and 93.3-103.3%, respectively, for the entire of the linear ranges. Spectrophotometric detection limit was 3 ng $mL^{?1}$ and effects of diverse ions on the first derivative determination of nickel were studied to investigate selectivity of the method. Interferences of cobalt and copper on the nickel determination were prevented using o-phenanthroline as masking agent. The recommended procedures were applied to the various synthetic and stainless steel alloys, tea leaves and human hair, with satisfactory results.

Numerical investigation and deep learning-based prediction of heat transfer characteristics and bubble dynamics of subcooled flow boiling in a vertical tube

Erfan Eskandari,Hasan Alimoradi,Mahdi Pourbagian,Mehrzad Shams 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Subcooled flow boiling presents an enormous ability of heat transfer rate, which is extremely important inthe heat-dissipating systems of many industrial applications, such as power plants and internal combustion engines. Using an Euler-Euler-based three-dimensional numerical simulation of subcooled flow boiling in a vertical tube, weinvestigated different heat transfer quantities (average and local heat transfer coefficient, average and local vapor volumefraction, average and local wall temperature) and bubble dynamics quantities (bubble departure diameter, bubbledetachment frequency, bubble detachment waiting time, and nucleation site density) under various boundary conditions(pressure, subcooled temperature, mass flux, heat flux). Numerical results show that an increase in heat flux leadsto the increase in all of the physical quantities of interest but the bubble detachment frequency. An entirely oppositebehavior is observed when we change the mass flux and inlet subcooled temperature. Furthermore, a rise in pressurereduces all of the target quantities but the wall temperature and bubble detachment frequency. Since numerical simulationof such multiphase flow requires significant computational resources, we also present a deep learning approach,based on artificial neural networks (ANN), to predicting the physical quantities of interest. Prediction results demonstratethat the ANN model is capable of accurately predicting the target quantities with mean absolute errors less than2.5% and R-squared more than 0.93.

Highly Selective Derivative Spectrophotometry for Determination of Nickel Using 1-(2-Pyridylazo)-2-naphthol in Tween 80 Micellar Solutions

Habibollah Eskandari* 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.8

Evaluation of the heart and lung dosimetric parameters in deep inspiration breath hold using 3D Slicer

Azam Eskandari,Shahrokh Nasseri,Hamid Gholamhosseinian,Sare Hosseini,Mohammad Javad Keikhai Farzaneh,Alireza Keramati,Maryam Naji,Atefeh Rostami,Mehdi Momennezhad 대한방사선종양학회 2020 Radiation Oncology Journal Vol.38 No.1

Purpose: The present study was conducted to compare dosimetric parameters for the heart and left lung between free breathing (FB) and deep inspiration breath hold (DIBH) and determine the most important potential factors associated with increasing the lung dose for left-sided breast radiotherapy using image analysis with 3D Slicer software. Materials and Methods: Computed tomography-simulation scans in FB and DIBH were obtained from 17 patients with left-sided breast cancer. After contouring, three-dimensional conformal plans were generated for them. The prescribed dose was 50 Gy to the clinical target volume. In addition to the dosimetric parameters, the irradiated volumes and both displacement magnitudes and vectors for the heart and left lung were assessed using 3D Slicer software. Results: The average of the heart mean dose (Dmean) decreased from 5.97 to 3.83 Gy and V25 from 7.60% to 3.29% using DIBH (p < 0.001). Furthermore, the average of Dmean for the left lung was changed from 8.67 to 8.95 Gy (p = 0.389) and V20 from 14.84% to 15.44% (p = 0.387). Both of the absolute and relative irradiated heart volumes decreased from 42.12 to 15.82 mL and 8.16% to 3.17%, respectively (p < 0.001); however, these parameters for the left lung increased from 124.32 to 223.27 mL (p < 0.001) and 13.33% to 13.99% (p = 0.350). In addition, the average of heart and left lung displacement magnitudes were calculated at 7.32 and 20.91 mm, respectively. Conclusion: The DIBH is an effective technique in the reduction of the heart dose for tangentially treated left sided-breast cancer patients, without a detrimental effect on the left lung.

Effects of near-fault records characteristics on seismic performance of eccentrically braced frames

Reyhaneh Eskandari,Davoud Vafaei 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.5

In this paper the effects of fling-step and forward-directivity on the seismic performance of steel eccentrically braced frames (EBFs) are addressed. Four EBFs with various numbers of stories (4-, 8-, 12- and 15-story) were designed for an area with high seismic hazard. Fourteen near-fault ground motions including seven with forward-directivity and seven with fling-step effects are selected to carry out nonlinear time history (NTH) analyses of the frames. Furthermore, seven more far-field records were selected for comparison. Findings from the study reveal that the median maximum links rotation of the frames subjected to three set of ground motions are in acceptable range and the links completely satisfy the requirement stated in FEMA 356 for LS performance level. The arrival of the velocity pulse in a near-fault record causes few significant plastic deformations, while many reversed inelastic cycles result in low-cycle fatigue damage in far-fault records. Near-fault records in some cases are more destructive and the results of these records are so dispersed, especially the records having fling-step effects.