Showing papers by "Azarbaijan Shahid Madani University published in 2019"

On fractional integro-differential inclusions via the extended fractional Caputo–Fabrizio derivation

Abstract: We first show that four fractional integro-differential inclusions have solutions. Also, we show that dimension of the set of solutions for the second fractional integro-differential inclusion problem is infinite dimensional under some different conditions.

Influence of multi-pass FSP on the microstructure, mechanical properties and tribological characterization of Al/B4C composite fabricated by accumulative roll bonding (ARB)

Abstract: This paper aims to understand the impact of post-multi-pass friction stir processing (FSP) on the microstructure, mechanical, wear and fracture behaviors of the fabricated 10 cycle-accumulative roll bonded Al-2%B4C composites. The increase in the number of tool-passes directly improved homogeneity and fragmentation of B4C particles, microhardness, tensile strength (86.84–173.92 MPa) and fracture resilience of the Al-2%B4C composite. The tribological properties of the composite are improved with a rise in the number of tool passes. Wear rate, upper boundaries and mid-fluctuation lines of the friction coefficient decreased from 6.198 × 10−5 to 1.095 × 10−5 mm3/Nm, 0.56 to 0.19, and 0.31 to 0.11 respectively as the number of tool passes was varied between 1 and 8 passes. An increase in the sliding distance caused an overshoot of the complete waveform of friction coefficient to be above the mid-line of fluctuation due to the induced frictional/thermal input emanating from the prolonged surface-surface contact. Homogenous particle dispersion imposes abrasion wear mechanism on the composite. Ductile fracture is the predominant failure mode of the composites. Post-multi-pass friction stir processing of the accumulative roll bonded Al-2%B4C composite is an effective approach of achieving high performance in Al-B4C composite.

On the new fractional hybrid boundary value problems with three-point integral hybrid conditions

Abstract: We investigate some new class of hybrid type fractional differential equations and inclusions via some nonlocal three-point boundary value conditions. Also, we provide some examples to illustrate our results.

Ni–Ti Layered Double Hydroxide@Graphitic Carbon Nitride Nanosheet: A Novel Nanocomposite with High and Ultrafast Sonophotocatalytic Performance for Degradation of Antibiotics

Abstract: Pollution of water resources by antibiotics is a growing environmental concern. In this work, nanocomposites of g-C3N4@Ni–Ti layered double hydroxides (g-C3N4@Ni–Ti LDH NCs) with high surface areas...

Heat transfer simulation during charging of nanoparticle enhanced PCM within a channel

Abstract: Current research contains numerical modeling of the melting process acceleration with nanoparticles. The upper layer filled with paraffin contains CuO nanoparticles. Air hot flow inside the lower layer makes the NEPCM to change its phase from solid to liquid. Such model can be employed in a building to control the temperature of air in the room. The mathematical model has been provided considering single phase model and has been solved via finite volume method. Outputs demonstrate that melt fraction enhances with increasing in concentration of CuO nanoparticles. By dispersing nanoparticles, the air outlet temperature augments and heat conduction become stronger in upper layer

Existence results for a fraction hybrid differential inclusion with Caputo–Hadamard type fractional derivative

Abstract: In this manuscript, we talk over the existence of solutions of a class of hybrid Caputo–Hadamard fractional differential inclusions with Dirichlet boundary conditions. Our results are based on the Arzela–Ascoli theorem and some suitable theorems of fixed point theory. As well, to illustrate our results, we confront the exceptional case of the fractional differential inclusions with examples.

Fire Detection for Video Surveillance Applications Using ICA K-Medoids-Based Color Model and Efficient Spatio-Temporal Visual Features

Abstract: Automated detection of fire flames in videos shot from a surveillance camera is an active research topic, as fire detection must be accurate and fast. The present study proposes and evaluates an efficient fire detection method. The contributions of this method lies in threefold: (1) a robust ICA (Imperialist Competitive Algorithm) K-medoids-based color model first is developed to reliably detect all candidate fire regions in a scene; (2) a motion-intensity-aware motion detection technique is introduced to simply extract the regions containing movement together with the motion intensity rate of every moving pixel, which are then used to analyze the characteristics of the fire; (3) a set of new spatio-temporal features having the distinct characteristics of fire flames are extracted from the candidate fire regions which are fed into a support vector machine classifier in order to distinguish real fire regions from non-real ones. The experimental results for a set of benchmark fire video datasets and videos provided in this research confirm that the proposed method outperforms state-of-the-art fire detection approaches, providing high detection accuracy and a low false detection rate.

On a three step crisis integro-differential equation

Abstract: One of the interesting fractional integro-differential equations is the three step crisis equation which has been reviewed recently. In this paper, we investigate the existence of solutions for a three step crisis fractional integro-differential equation under some boundary conditions.

ZnS quantum dot intercalated layered double hydroxide semiconductors for solar water splitting and organic pollutant degradation

Abstract: Heterostructured nanocomposites consisting of MIIZnAl-layered double hydroxide/ZnS quantum dots (MII = Co or Mn) are constructed to utilize the unique properties of the wide band gap ZnS quantum dots (QDs) and layered double hydroxides (LDHs) for visible light driven photocatalytic applications. The nanocomposites were synthesized via the in situ growth of oppositely charged 2D LDHs in the presence of negatively charged ZnS QDs. The partial intercalating of ZnS QDs in the interlayer space of the LDHs is evidenced by powder X-ray diffraction results. In comparison with ZnS QDs and pristine LDHs, the prepared CoZnAl-LDH/ZnS and MnZnAl-LDH/ZnS heterostructures show surprisingly enhanced visible light harvesting ability with an expansion of the ligand to metal charge transfer absorption edge to visible wavelengths. The obtained results imply effective electronic coupling between ZnS QDs and LDHs. The charge carrier recombination is largely suppressed, as indicated by the photoluminescence and electrochemical impedance spectroscopy results. From the Tauc and Mott–Schottky plots, the band structures of the synthesized heterostructures were determined. The resulting heterostructures reveal promising activity for visible light photocatalytic oxygen evolution via water splitting and the degradation of Acid Red 14, as a model organic pollutant, and significantly enhanced photostability, much superior to pristine LDHs and ZnS QDs.

Current approaches in identification and isolation of cancer stem cells

Abstract: Cancer stem cells (CSCs) are tumor cells with initiating ability, self-renewal potential, and intrinsic resistance to conventional therapeutics. Efficient isolation and characterization of CSCs pave the way for more comprehensive knowledge about tumorigenesis, heterogeneity, and chemoresistance. Also a better understanding of CSCs will lead to novel era of both basic and clinical cancer research, reclassification of human tumors, and development of innovative therapeutic strategies. Finding novel diagnostic and effective therapeutic strategies also enhance the success of treatment in cancer patients. There are various methods based on the characteristics of the CSCs to detect and isolate these cells, some of which have recently developed. This review summarized current techniques for effective isolation and characterization of CSCs with a focus on advantages and limitations of each method with clinical applications.

The adsorption of sulfur trioxide and ozone molecules on stanene nanosheets investigated by DFT: Applications to gas sensor devices

Abstract: Recent findings shed light on performing fundamental experiments for preparation of metal monolayer stanene, which is a zero band gap semiconductor material with buckled honeycomb structure . Stanene possesses outstanding physical and mechanical properties , and has been extensively investigated in the field of nanoelectronic devices. We performed a theoretical study on the adsorption behaviors of O 3 and SO3 molecules on two-dimensional stanene sheet in order to fully exploit the promising gas sensing capability of these materials. We examined the most stable structures of O3 and SO3 molecules adsorbed on the stanene, and examined the adsorption process in view of the energetics , charge transfers and electronic structure of the adsorption systems. The results indicate that the adsorption of gas molecules on the B-doped stanene is more favorable in energy than that on the pristine one, representing the superior sensing performance of B-doped system. Our charge analysis based on Mulliken charges reveals a charge transfer from the stanene sheet to the adsorbed O 3 and SO3 molecules, as evidenced by charge accumulation on the adsorbed molecules. This indicates the gas molecules act as charge acceptors from the stanene sheet. The significant overlaps between the PDOS spectra of the interacting atoms indicate the formation of chemical bonds between these atoms. Our findings thus suggest that B-doped stanene could be a highly efficient gas sensor device for SO3 and O3 detection in the environment.

A new local and multidimensional ranking measure to detect spreaders in social networks

Abstract: Spreaders detection is a vital issue in complex networks because spreaders can spread information to a massive number of nodes in the network. There are many centrality measures to rank nodes based on their ability to spread information. Some local and global centrality measures including DIL, degree centrality, closeness centrality, betweenness centrality, eigenvector centrality, PageRank centrality and k-shell decomposition method are used to identify spreader nodes. However, they may have some problems such as finding inappropriate spreaders, unreliable spreader detection, higher time complexity or incompatibility with some networks. In this paper, a new local ranking measure is proposed to identify the influence of a node. The proposed method measures the spreading ability of nodes based on their important location parameters such as node degree, the degree of its neighbors, common links between a node and its neighbors and inverse cluster coefficient. The main advantage of the proposed method is to clear important hubs and low-degree bridges in an efficient manner. To test the efficiency of the proposed method, experiments are conducted on eight real and four synthetic networks. Comparisons based on Susceptible Infected Recovered and Susceptible Infected models reveal that the proposed method outperforms the compared well-known centralities.

Quantum thermometry by single-qubit dephasing

Abstract: We address the dephasing dynamics of a qubit as an effective process to estimate the temperature of its environment. Our scheme is inherently quantum, since it exploits the sensitivity of the qubit to decoherence, and does not require thermalization with the system under investigation. We optimize the quantum Fisher information with respect to the interaction time and the temperature in the case of Ohmic-like environments. We also find explicitly the qubit measurement achieving the quantum Cramer-Rao bound to precision. Our results show that the conditions for optimal estimation originate from a non-trivial interplay between the dephasing dynamics and the Ohmic structure of the environment. In general, optimal estimation is achieved neither when the qubit approaches the stationary state, nor for full dephasing.