Sharif Digital Repository

A novel magnetic nanocarrier with long spacer length and high colloidal stability has been prepared for effective delivery of doxorubicin (DOX). First, poly(amidoamine) (PAMAM) dendrimer was grown up onto the surface of superparamagnetic iron oxide nanoparticles to increase the loading amount of amine groups. Then, terminal amine groups were functionalized by polyethylene glycol dimethylester to increase the spacer length. Then anticancer drug DOX was covalently attached onto the system by hydrazone bond to forms a pH-sensitive nanocarrier. This system is designed to combine the advantage of magnetic targeting, high drug loading capacity, and controlled release  

Implementation of new materials in automotive body-in-white requires through knowledge of their metallurgical response to welding process thermal cycle. This two-part paper aims at understanding the physical and mechanical metallurgy of stainless steels, as interesting candidates for automotive application, during resistance spot welding. The second part addresses the phase transformations in the heat affected zone of three types of stainless steels including austenitic, ferritic and duplex steels. Failure modes and mechanical properties of stainless steel resistance spot welds are discussed. The peak load and energy absorption of stainless steel resistance spot welds are compared with... 

This paper addresses the microstructure and mechanical performance of dissimilar resistance spot welds between AISI 430 ferritic stainless steel and drawing quality special killed (DQSK) low-carbon steel. The mechanical properties of the welds are described by peak load, failure energy, and failure mode during the tensile-shear test. Phase transformations in the fusion zone (FZ) and heat-affected zone (HAZ) are analyzed. The main metallurgical features of the weldment are the formation of a dual-phase, ferrite-martensite microstructure in the FZ, grain growth and martensite formation in the HAZ of the ferritic stainless steel side, and martensitic and eutectoid transformations in the HAZ of... 

In this paper, nano/microstructured-conducting polypyrrole has been prepared on Cu/Au interdigital electrode surfaces by using constant potential amperometry technique. The Fe(II) ions were used as catalyst and X = ClO4 -, pTs-, Cl-, TCA-, DS-, DBS- was implemented as anion dopants. The morphologies of the films were investigated by field emission scanning electron microscope. A remarkable dependence was observed between the type of anion dopant and the morphology of polypyrrole (PPy). The sensing behavior of the PPy-X sensor has been studied toward acetone, methanol, ethanol, 1-propanol, 2-propanol, nitromethane, propylamine, pyridine, and gas mixtures of aliphatic alcohols. The responses... 

In this paper, we characterize complete partite zero-divisor graphs of posets via the ideals of the posets. In particular, for complete bipartite zero-divisor graphs, we give a characterization based on the prime ideals of the posets  

Semantic Textual Relatedness holds significant relevance in Natural Language Processing, finding applications across various domains. Traditionally, approaches to STR have relied on knowledge-based and statistical methods. However, with the emergence of Large Language Models, there has been a paradigm shift, ushering in new methodologies. In this paper, we delve into the investigation of sentence-level STR within Track A (Supervised) by leveraging fine-tuning techniques on the RoBERTa transformer. Our study focuses on assessing the efficacy of this approach across different languages. Notably, our findings indicate promising advancements in STR performance, particularly in Latin languages.... 

Boosting is a general method for improving the accuracy of any given learning algorithm. In this paper, we have proposed the boosting method for face recognition (FR) that improves the linear discriminant analysis (LDA)-based technique. The improvement is achieved by incorporating the regularized LDA (R-LDA) technique into the boosting framework. R-LDA is based on a new regularized Fisher's discriminant criterion, which is particularly robust against the small sample size problem compared to the traditional one used in LDA. The AdaBoost technique is utilized within this framework to generalize a set of simple FR subproblems and their corresponding LDA solutions and combines the results from... 

Background: The cooling system is one of the important parts of new devices such as smartphones, servers, and other electrical devices. By employing the almost all heat transfer methods such as conduction, evaporation and condensation, heat pipes are the best choice to increase the heat transfer. The thermal conductivity of heat pipe is much higher than fins because they benefit from condensation and evaporation simultaneously. Methods: This study tries to present relative thermal conductivity base on temperature and length of a heat pipe in optimized geometry. To achieve this aim, unsteady, multiphase fluid was considered inside the heat pipe. Evaporation, condensation, and conduction were... 

The power supply of microwave tubes has high voltage and the possibility of produce high power pulse, which called in modulator. In this work, the results of design, construction and characterization of a direct drive pulse modulator for driving high power short pulse-width magnetron are reported. The sub-assemblies of modulator are; a primary high voltage supply, a switch bank with drivers and snubber circuits, a filament circuit, a digital control circuit with sensors and finally a pulse transformer. This paper is concerned with introduction and presentation of experimental evaluation of a new drive method for high power high voltage modulating-cathode microwave tubes. ©2009 IEEE  

Poisson Factorization (PF) is the gold standard framework for recommendation systems with implicit feedback whose variants show state-of-the-art performance on real-world recommendation tasks. However, they do not explicitly take into account the temporal behavior of users which is essential to recommend the right item to the right user at the right time. In this paper, we introduce Recurrent Poisson Factorization (RPF) framework that generalizes the classical PF methods by utilizing a Poisson process for modeling the implicit feedback. RPF treats time as a natural constituent of the model, and takes important factors for recommendation into consideration to provide a rich family of... 

In this paper, the performance of the class-J mode power amplifier (PA) is studied when an auxiliary network performs active load modulation on the main transistor. Load modulation is realized by injecting an additional class-C like current with conduction angle of $alpha $ to the drain node of the main transistor. The injected current employs a phase shift of $phi $ with respect to the half-sinusoidal current of the main transistor, and its maximum value is tuned with the size of the transistor used in the auxiliary network. Detailed theoretical formulations are presented for the optimal load impedances of the PA at the fundamental and second-harmonic frequencies. Furthermore, the output... 

Naive Bayes (NB) classifier ease of use along with its remarkable performance has led many researchers to extend the scope of its applications to real-world domains by relaxing the conditional independence assumption of features given the information about the class variable. However, fulfilling this objective, most of the generalizations, cut their own way through compromising the model's simplicity, make more complex classifiers with a substantial deviation from the original one. Multi Independent Latent Component Naive Bayes Classifier (MILC-NB) leverages a set of latent variables to preserve the overall structure of naive Bayes classifier while rectifying its major restriction. Each... 

In this paper, we deal with zero-divisor graphs of posets. We prove that the diameter of such a graph is either 1, 2 or 3 while its girth is either 3, 4 or ∞. We also characterize zero-divisor graphs of posets in terms of their diameter and girth  

Electrification of energy systems, including an increased percentage of electric vehicles on the road, is one of the primary paths to achieve zero carbon emissions. However, a reduced share of fossil fuel in transportation and industry requires a significant shift in power generation energy sources. Power generation from renewable sources is still limited and will be for the foreseeable future. Developing countries and oil-producing nations in the middle east may shift to electric vehicles, but electricity energy sources will not be easily moved to renewables., A detailed and comprehensive emission inventory was developed in a bottom-up method for a typical populated city in Iran,... 

Many highly populated cities are still struggling to reach clean air targets, while the zero greenhouse gas emission objectives may accelerate the path toward healthy air for all. Still, there is a fine line between intensive electrification's impact on greenhouse gas emissions and criteria air contaminants depending on the source of the electricity. In this study, the previous version of the emission inventory for Tehran was evaluated and re-calculated in a detailed bottom-up approach to provide the most updated data on the contribution of stationary sources derived by power plants vs. mobile sources. The objectives were to update the emission inventory for improved policymaking, study the... 

Many oil reservoirs encounter asphaltene precipitation as a major problem during natural production. In spite of numerous experimental studies, the effect of temperature on asphaltene precipitation during pressure depletion at reservoir conditions is still obscure in the literature. To study their asphaltene precipitation behavior at different temperatures, two Iranian light and heavy live oil samples were selected. First, different screening criteria were applied to evaluate asphaltene instability of the selected reservoirs using pressure, volume, and temperature data. Then, a high pressure, high temperature filtration (HPHT) setup was designed to investigate the asphaltene precipitation... 

In this paper, two output matching networks (OMNs) are proposed for integrated class-J and class-J-1 mode power amplifiers (PAs). The first MN provides the required load impedances of the class-J mode (i.e., Z(f0) = Ropt + j Ropt and Z(2 f0) = -j (3π/8)Ropt), where as the second MN realizes the optimal impedances of class-J-1 PAs (i.e., Z(f0) = Ropt - j Ropt and Z(2 f0) = j (3π/8)Ropt ). Detailed theoretical analyses are presented for each MN, and the values of matching components (i.e., inductors and capacitors) are obtained in terms of Ropt. Analytical derivations are verified by simulation results, while bandwidth and loss performances of each MN are also characterized. Two... 

Human-generated droplets constitute the main route for the transmission of coronavirus. However, the details of such transmission in enclosed environments are yet to be understood. This is because geometrical and environmental parameters can immensely complicate the problem and turn the conventional analyses inefficient. As a remedy, this work develops a predictive tool based on computational fluid dynamics and machine learning to examine the distribution of sneezing droplets in realistic configurations. The time-dependent effects of environmental parameters, including temperature, humidity and ventilation rate, upon the droplets with diameters between 1 and 250μm are investigated inside a... 

Steam injection process has been considered for a long time as an effective method to exploit heavy oil resources. Over the last decades, Steam Assisted Gravity Drainage (SAGD) has been proved as one of the best steam injection methods for recovery of unconventional oil resources. Recently, Fast-SAGD, a modification of the SAGD process, makes use of additional single horizontal wells alongside the SAGD well pair to expand the steam chamber laterally. This method uses fewer wells and reduces the operational cost compared to a SAGD operation requiring paired parallel wells one above the other. The efficiency of this new method in naturally fractured reservoir is not well understood.... 

A multi-microgrid system – containing various complementary energy sources – must coordinate the power flow among microgrids and the utility grid for stability and reliability enhancement, and also should obtain optimum energy management. Multi-agent-based optimization techniques are ideal for the management of interconnected microgrids, due to their decentralized nature and multifactorial approach in the decision-making process. In this paper, an optimization model is proposed for interconnected multi microgrids which considers the overall cost of the system. For optimum system operation, the hierarchical energy management system is utilized based on the multi-agent systems (MAS) theory....