Sharif Digital Repository

A new approach for static state feedback linearization of single input and multi-input systems is put forward. The approach can be applied to wider class of systems than the classical feedback linearization. The main idea is to transform the nonlinear system via a change of coordinates and static state feedback into a linear system with desired dynamics. This circumvents the need to transform the input vector fields into constant vectors in the new coordinates. An amine gas sweetening process has been simulated as a nonlinear system, then the system is linearized using the approximate fuzzy feedback linearization method. The rules of the fuzzy system have been optimized by genetic algorithm... 

In this article, solving the population balance equation (PBE) and controlling the final particle size for crystallization problems have been addressed. For solving the general form of multidimensional PBE, a numerical method called conservation element and solution element (CE/SE) has been used. By applying this method to one- and two-dimensional crystallization problems, it has been shown that this technique can handle all types of source terms in the PBE. Model accuracy has been checked with experimental data reported in the literature and also with the analytical solution of PB-type equations. Control of final particle size was formulated in an optimization framework. To obtain a desired... 

Clustering is the term used in several research communities to describe methods for grouping of unlabeled data. The objective in clustering is to divide the data set in such a way that the intra-class similarity is high and inter-class similarity is low. It is very helpful to find a system's states distributions, but when the system's scale is large, e.g., considering a distillation column that has crude oil as its feed, if one of desired is finding concentration of most popular hydrocarbons (ethane, propane, octane, etc.) on each tray, it should be solve species continuity for each component. A mixture of 100 hydrocarbons was classified into 10 clusters by different clustering methods,... 

Pore facies analysis plays an important role in the classification of reservoir rocks and reservoir simulation studies. The current study proposes a two-step approach for pore facies characterization in the carbonate reservoirs with an example from the Kangan and Dalan formations in the South Pars gas field. In the first step, pore facieswere determined based on Mercury Injection Capillary Pressure (MICP) data in corporation with the Hierarchical Clustering Analysis (HCA) method. Each pore facies represents a specific type of pore geometry indicating the interaction between the primary rock fabric and its diagenetic overprints. In the next step, polynomial meta-models were established based... 

Large-scale simulation of spiking neural networks on hardware with a remarkable resemblance to their mathematical models is a key objective of the neuromorphic discipline. This issue is, however, considerably resource-intensive due to the presence of nonlinear terms in neuron models. This paper proposes a novel uniform piecewise linear segmentation approach for nonlinear function evaluations. Employing the proposed approach, we present a uniform-segmented adaptive exponential neuron model capable of accurately producing various responses exhibited by the original model and suitable for efficient large-scale implementation. In contrast to previous nonuniform-segmented neuron models, the... 

Computational investigations on the gas phase SN2 reactions of X ions (X-=OH-,F-,Cl-,Br-, and I-) with fluoroethane and 2-fluoroethanol (β-hydroxyl ethyl fluoride) were performed by using MPW1K, M06 and CCSD(T) methods with a range of basis sets including 66-311++G**, TZVP, aug-cc-pVDZ and SDD. To better understand the nature of the corresponding intermolecular interactions, we performed natural bond orbital (NBO) analysis and Bader's quantum theory of atoms in molecules (QTAIM). In our calculations, we took into account two possible pathways for these reactions, i.e. SN2 reactions of 2-fluoroethanol. In path(i), β-hydroxyl group participates in hydrogen bonding... 

This work presents a novel closed-form expression based on the method of moments (MoM) for solving the scattering problem in piecewise homogeneous media. Using point matching with pulse-basis functions in MoM, we derive an expression that represents the scattered field as an explicit function of the permittivity value of each homogeneous part. The coefficient matrix depends on the permittivity values in the MoM solution to the scattering problem. Therefore, it requires matrix inversion whenever these values change slightly. Here, we propose a new expression where the matrix coefficients are independent of the permittivity values of each homogeneous part. Accordingly, when the geometry does... 

In this study, we present a novel approach to address nonweak scattering problems by integrating deep learning (DL) into the Born series. Typically, the first-order Born approximation (BA) is limited to cases where the contrast between the scatterer and the background medium is exceptionally low. While higher-order terms in the Born series can be used for higher contrasts, convergence issues may arise due to highly oscillatory factors in Green's function. To overcome this limitation, we introduce a physics-based DL method inspired by the Born series, which effectively predicts the distribution of the complex electromagnetic field. The proposed series assures convergence when scattering... 

In this paper, the V-shape development model approach for designing an automotive floor panel made by laminated structure is investigated to attain the best trade-off between the system and subsystem level requirements while improving the local and global performance of the vehicle. For this purpose, the bending and torsional stiffness of the body structure, as well as mass, strength, and vibration attenuation of the floor panel, are considered as design objectives at the system and subsystem levels. A multi-objective discrete optimization of a laminated configuration is performed using the Taguchi-based grey relational analysis. Material grades and thicknesses of the sandwich panel face... 

Low structure carbon black (CBN330), conductive high structure carbon black (CBXE2B) and carboxylated multiwalled carbon nanotube (MWCNT) were loaded into the blend of natural rubber (NR) and styrene butadiene rubber (SBR) at different contents up to 10 phr. Kraus plots showed that all the reinforcements interact with NR/SBR blend appropriately. However, the CBXE2B whose interfacial area is the highest showed greatest value of Kraus interaction parameter. Flory-Rhener model and effective torque value revealed that all of the reinforcements enhanced the crosslink density, among them CBXE2B showed the highest impact and MWCNT placed in the second rank. It was also shown that the cure kinetic... 

A novel substrateless power amplifier module realized by ridge gap waveguide (RGW) technology is proposed in Ka-band. Up to our knowledge, this is the first time that an active device is directly integrated with an RGW structure. No substrate is used in the RF section of the implemented power amplifier and the whole structure is made by machining a piece of metal. The amplifier was made of two pieces and was easily assembled without needing a precise contact between the two sections. The cavity resonance of the amplifier is suppressed using a pining structure. The fabricated amplifier module is self-packaged and does not need any packaging. It is shown that the simulated and measured results... 

The reinforcing effect of high structure carbon black (HSCB) and multi-walled carbon nanotubes (MWCNTs) on natural rubber/styrene-butadiene rubber blend processed using mechanical mixing was comparatively investigated. In-depth analysis by dynamic mechanical analysis, the Eggers-Schummer model and Medalia's relationship showed that HSCB aggregates provided large internal pores leading to significant immobilized macromolecules in filled rubber. Additionally, a tubular immobilized rubber layer with a thickness of 8nm was estimated for the rubber/MWCNT system based on dynamic mechanical analysis data. The mechanical performance of the HSCB filled blend was higher than that of the MWCNT filled... 

Novel types of narrow band filters based on the newly introduced gap waveguide technology are presented in this paper. The proposed filters have a central frequency of 35 GHz with approximately 1% fractional bandwidth. The filter resonators are composed of two separate plates and are manufactured by milling metallic blocks. The gap between the two metallic plates eliminates the need for electrical contact between them. This feature allows the resonators to be stacked in different layers. The filtering function is realized by producing a coupling between the stacked resonators. The measurement results of the manufactured filters are in good agreement with full-wave simulations, even without... 

A half power divider using ridge gap waveguide technology is realized in millimeter wave frequencies. By machining a piece of metal the divider was fabricated. There is no need to an electrical connection between the divider constitutive parts. The fabricated divider is self-packaged. Cylindrical pins are used in the divider structure for ease of fabrication. Low loss power division and good isolation between ports is measured. Also the measured impedance matching of the divider ports is acceptable. Good agreement between the simulation and measurement is achieved. © 2016 IEEE  

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

Varactor frequency multipliers often show parametric instability with increasing RF input power. Examination of the added phase noise of the varactor frequency multipliers show that, if parametric oscillations are present in the circuit, output phase noise degrades remarkably in some specific driving levels. Phase noise analysis is done by the conversion matrix method. The conversion method predicts the phase noise degradation precisely because it encounters the noise conversion by large driving levels. The added phase noise of a varactor frequency doubler with subharmonic oscillation is calculated and the simulation results are compared with measurement results. Both simulation and... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

In this work, a theorem is proved stating that in various types of waveguides with mirror reflection symmetries, the electromagnetic duality correspondence between eigenmodes of complementary structures induces counterpropagating spin-polarized states. The mirror reflection symmetries may be preserved around one or more arbitrary planes. Pseudospin-polarized waveguides supporting one-way states manifest robustness. This is similar to topologically non-trivial direction-dependent states guided by photonic topological insulators. Nevertheless, a remarkable aspect of our structures is that they can be implemented in extremely broad bandwidth by simply using complementary structures. Based on...