Sharif Digital Repository

The belief propagation algorithm is a state of the art decoding technique for a variety of linear codes such as LDPC codes. The iterative structure of this algorithm is reminiscent of a neural network with multiple layers. Indeed, this similarity has been recently exploited to improve the decoding performance by tuning the weights of the equivalent neural network. In this paper, we introduce a new network architecture by increasing the number of variable-node layers, while keeping the check-node layers unchanged. The changes are applied in a manner that the decoding performance of the network becomes independent of the transmitted codeword; hence, a training stage with only the all-zero... 

This paper addresses design of an adaptive fuzzy decentralized fault-tolerant controller for a class of uncertain multi-input multi-output (MIMO) large-scale nonlinear systems with unmodeled dynamics subject to unknown state time-varying delay, external disturbances, unknown input saturation and actuator faults. It is shown that the proposed fault-tolerant control (FTC) scheme can handle infinite number of actuator failures including partial and total loss of effectiveness. System uncertainties have been approximated by the fuzzy logic systems (FLSs). To cope with the unknown state time-varying delay, the Razumikhin lemma has been utilized and unmodeled dynamics has been tackled by... 

In this paper, the design of an adaptive tracking control for a class of switched uncertain multiple-input–multiple-output nonlinear systems in the strict-feedback form with unmodeled dynamics in the presence of three types of input nonlinearity under arbitrary switching has been addressed. By means of an intelligent approximator like a fuzzy logic system or a neural network, the unknown dynamics are estimated. The unmodeled dynamics have been tackled with a dynamic signal. A universal framework for describing different types of input nonlinearity including saturation, backlash, and dead zone has been utilized. By applying the backstepping approach and the common Lyapunov function method,... 

Fluorine-doped tin oxide (FTO) nano-powders were synthesized by a gel combustion method. To analyse the effect of processing factors and their interactions and to achieve an equation for nano-powder particle size in terms of code factors, D-optimal factorial design was used. Stannous chloride penta-hydride, ammonium fluoride and citric acid were used to synthesize the FTO nano-powders. The structure, morphology and composition of the synthesized powders were characterized by X-ray diffraction, field emission scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The results revealed the formation of homogenous FTO nano-powders with an average particle size of 20 nm... 

This paper addresses an adaptive observer-based control for a switched fractional-order uncertain nonlinear system subject to input nonlinearities and asymmetric output constraints. The switching signal is arbitrary, and the designed controller needs no information regarding this signal. By employing a universal framework, the designed controller can cope with different input nonlinearities in different modes without having any information about their characteristics. It is assumed that only system output is measured, and a designed observer estimates the system states for control implementation. The uncertainties are approximated by intelligent approximators like fuzzy logic systems (FLS)... 

Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface... 

Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface... 

In the bone tissue engineering field (BTE), it is of significant importance to develop bioactive multifunctional scaffolds with enhanced osteoconductivity, osteoinductivity, and antibacterial properties required for lost bone tissue regeneration. In this work, a bioactive glass-ceramic scaffold was manufactured via a novel polymer-derived ceramics (PDC) manufacturing method. To gain antibacterial properties, the silver ions were incorporated in controlled amount along with other precursors in the PDC processing stage. Microstructural and structural properties of the fabricated silicate-phosphate glass-ceramic scaffold were evaluated by scanning electron microscopy (SEM) equipped with energy... 

In the bone tissue engineering field (BTE), it is of significant importance to develop bioactive multifunctional scaffolds with enhanced osteoconductivity, osteoinductivity, and antibacterial properties required for lost bone tissue regeneration. In this work, a bioactive glass-ceramic scaffold was manufactured via a novel polymer-derived ceramics (PDC) manufacturing method. To gain antibacterial properties, the silver ions were incorporated in controlled amount along with other precursors in the PDC processing stage. Microstructural and structural properties of the fabricated silicate-phosphate glass-ceramic scaffold were evaluated by scanning electron microscopy (SEM) equipped with energy... 

Gene therapy involves replacing a faulty gene or adding a new gene inside the body's cells to cure disease or improve the body's ability to fight disease. Its popularity is evident from emerging concepts such as CRISPR-based genome editing and epigenetic studies and has been moved to a clinical setting. The strategy for therapeutic gene design includes; suppressing the expression of pathogenic genes, enhancing necessary protein production, and stimulating the immune system, which can be incorporated into both viral and non-viral gene vectors. Although non-viral gene delivery provides a safer platform, it suffers from an inefficient rate of gene transfection, which means a few genes could be... 

Formation of unstable solid electrolyte interphase (SEI) layers lacking of thermal stability in non-aqueous electrolytes of rechargeable batteries is the main bottleneck for their long-life cycling, especially at elevated temperatures. Inclusion of a small dose of functional electrolyte additives into the batteries' electrolyte can be highly beneficial to surmount this issue. Of these additives, vinylene carbonate (VC) has drawn particular attention thanks to its high ability to build protective layers at anodes showing good integrity and outstanding thermal stability. In addition to its primary roles in present-day lithium-ion batteries (LIBs), VC additive has also been examined in other... 

In a typical surveillance radar, decision about the existence of a target in certain range-azimuth-elevation cell is made from the echo received in current scan, while still there is useful information in history of that range cell that is not considered in decision making. Based on the potential of the Hough Transform to use history of both range and Doppler information, a new method to increase the probability of detection in surveillance radars is proposed. The new method uses a 3D data space and a special projection to detect targets and extract range, speed, and acceleration of maneuvering targets simultaneously  

Spinel ferrites (MFe2O4) and their binary composites with polymers are frequently used to remove and degrade organic dyes due to their magnetic, optical, and biocompatible features. In this study, NiFe2O4, as a superparamagnetic core, was coated using the deposition of polyethylenimine (PEI) and in-situ oxidative polymerization of pyrrole (py). Fourier-transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were employed to analyze NiFe2O4, NiFe2O4@PEI, and NiFe2O4@PPy nanospheres. The morphology and chemical composition of nanoparticles were investigated using field emission scanning electron microscopy (FESEM). The formation of core–shell... 

The reduced graphene oxide-Fe2O3 (rGO-Fe2O3) nanocomposites were synthesized by a facile and low-cost hydrothermal method employing rGO and Iron (III) nitrate precursors. The synthesis parameters including the reduction time and presence of reduction aid are studied. The structural and morphological studies of the nanocomposites were investigated by using Raman spectra, Fourier transform infrared spectroscopy, X-ray diffraction, and field emission scanning electron microscopy. The results indicate that Fe2O3 nanoparticles with average particle size of 25 nm are well anchored on graphene sheets and the weight percent of the nanoparticles in the nanocomposites was influenced by the reduction... 

In the present study, a bioactive silicate-phosphate glass-ceramic scaffold was fabricated via the polymer-derived ceramics (PDC) method. K2HPO4 phosphate salt was used as the P2O5 precursor in this method. The effect of K2HPO4 wt% and heat treatment temperatures (900–1100 °C) was evaluated. It was observed that although increasing the wt% of K2HPO4 led to the formation of scaffolds with higher densities and strengths, it could also increase the formation of the calcium phase, which could result in improper release behavior of scaffolds. On the other hand, higher heat treatment temperatures enhanced the strength of the scaffolds but eliminated the bioactive octacalcium phosphate (OCP) phase.... 

In the present study, a bioactive silicate-phosphate glass-ceramic scaffold was fabricated via the polymer-derived ceramics (PDC) method. K2HPO4 phosphate salt was used as the P2O5 precursor in this method. The effect of K2HPO4 wt% and heat treatment temperatures (900–1100 °C) was evaluated. It was observed that although increasing the wt% of K2HPO4 led to the formation of scaffolds with higher densities and strengths, it could also increase the formation of the calcium phase, which could result in improper release behavior of scaffolds. On the other hand, higher heat treatment temperatures enhanced the strength of the scaffolds but eliminated the bioactive octacalcium phosphate (OCP) phase.... 

In the present study, a bioactive silicate-phosphate glass-ceramic scaffold was fabricated via the polymer-derived ceramics (PDC) method. K2HPO4 phosphate salt was used as the P2O5 precursor in this method. The effect of K2HPO4 wt% and heat treatment temperatures (900–1100 °C) was evaluated. It was observed that although increasing the wt% of K2HPO4 led to the formation of scaffolds with higher densities and strengths, it could also increase the formation of the calcium phase, which could result in improper release behavior of scaffolds. On the other hand, higher heat treatment temperatures enhanced the strength of the scaffolds but eliminated the bioactive octacalcium phosphate (OCP) phase.... 

In water resources, organic dyes are known as poisonous substances. As a result, photocatalytic treatment of pollutants has been implemented to address water quality challenges. In the present study, nanocomposite of Nd-doped ZnO (ZnO:Nd) and polypyrrole (PPy) was synthesized via in-situ polymerization to enhance the photodegradation of Methyl orange (MO) and Methylene blue (MB). The formation of PPy/ZnO:Nd nanocomposite was confirmed using Fourier-transform infrared spectra (FTIR) and X-ray diffraction (XRD). The activation energy and thermal stability of prepared samples were investigated by Simultaneous Thermal Analysis (STA). X-ray photoelectron spectroscopy (XPS) demonstrated that Nd... 

In this paper, the problem of matrix rank minimization under affine constraints is addressed. The state-of-the-art algorithms can recover matrices with a rank much less than what is sufficient for the uniqueness of the solution of this optimization problem. We propose an algorithm based on a smooth approximation of the rank function, which practically improves recovery limits on the rank of the solution. This approximation leads to a non-convex program; thus, to avoid getting trapped in local solutions, we use the following scheme. Initially, a rough approximation of the rank function subject to the affine constraints is optimized. As the algorithm proceeds, finer approximations of the rank... 

Supercapacitors are environmentally friendly and safe energy storage devices for diverse applications. The electrode material's structural, microstructural, and electrochemical properties are crucial determinants of supercapacitor capacity. One effective method to improve electrode performance is introducing doping heteroatoms or synthesizing composite materials. In this study, three-dimensional reduced graphene oxide (3D rGO) doped with Phosphorus, Nitrogen, or both (N/P co-doped) was synthesized for high-efficiency, supercapacitors using a facile, fast, and cost-effective hydrothermal process. The hydrothermal reduction of graphene oxide involved substituting Phosphorus and Nitrogen...