Sharif Digital Repository

Material properties and fracture characteristics are among the most prominent parameters that should be considered for a wide range of graphene applications. This article reviews recent advances in theoretical studies on the mechanical properties and fracture behaviors of graphene, focusing on the effect of various simulation models. Most studies investigated single-layer graphene sheets (SLGSs) under uniaxial tensile tests using different common interatomic potentials, particularly AIREBO. Although researchers have examined a similar problem, specifically for pristine graphene, the differences in the reported values are considerable. These discrepancies are most evident in fracture... 

The peridynamic (PD) theory is a nonlocal reformulation of mechanics with various advantages over common approaches, mainly local continuum mechanics and molecular dynamics (MD). PD theory can capture phenomena at different dimensions, including nanoscale. However, limited studies have been performed by this theory in nanoscale, which have generally focused on the feasibility and accuracy of using PD in atomic-scale modeling. In the present study, based on the ordinary state-based peridynamic method, we investigate the fracture of pre-cracked single layer graphene sheets (SLGSs) under uniaxial tension. By simulating the exact atomic model of graphene, the failure strain and crack growth... 

For a wide range of graphene applications, it is required to examine the fracture characteristics of single-layer graphene sheets. In this article, we study the effective parameters in fracture of graphene, concentrating on the impact of atomistic modeling on results that have not been adequately evaluated in previous studies. We considered two distinct models to simulate a uniaxial tensile test in molecular dynamics. By comparing these models, we explore the influence of various parameters on the results, particularly fracture strength and failure strain. We demonstrate that in pristine graphene sheets, failure depends entirely on simulation modeling. The two main factors that lead to these... 

Background: Using foot orthoses for managing medial knee osteoarthritis (MKOA) is common, although its effectiveness is in debate. Most orthoses are placed inside the shoe as a lateral wedged insole. Thus, most studies in this area have focused on the effect of insoles used with shoes. This study compared the effects of a lateral wedge with subtalar strap (combined insole) used while barefoot and lateral wedged insole fitted within sandal on pain, function and external knee adduction moment (EKAM) in patients with MKOA to consider which orthotic treatment is better. Methods: In this quasi-experimental pretest–posttest study, 29 participants with medial knee osteoarthritis were divided into... 

Background: Using foot orthoses for managing medial knee osteoarthritis (MKOA) is common, although its effectiveness is in debate. Most orthoses are placed inside the shoe as a lateral wedged insole. Thus, most studies in this area have focused on the effect of insoles used with shoes. This study compared the effects of a lateral wedge with subtalar strap (combined insole) used while barefoot and lateral wedged insole fitted within sandal on pain, function and external knee adduction moment (EKAM) in patients with MKOA to consider which orthotic treatment is better. Methods: In this quasi-experimental pretest–posttest study, 29 participants with medial knee osteoarthritis were divided into... 

MFI zeolite membranes were prepared on porous α-alumina substrates, using secondary growth of nano-seeded layers. The resulting membranes were characterized by means of Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD), and pervaporation performance tests for separation of Benzene, Toluene and Xylene (BTX) mixture from contaminated water. The morphology, thickness, homogeneity, crystal preferential orientation and permeation properties of these membranes have been studied in relation to the seed layers. Successful separation of BTX mixture from water was performed by using the manufactured MFI zeolite membrane. The influence of temperature, feed concentration on the membrane... 

Nowadays, energy supply is one of the most prominent demands of countries in the world. The enhancement in energy efficiency, flexibility for applications in various industrial processes, and the reduction in the environmental impacts of pollutant emissions can be accomplished by using sustainable energy sources. Alternative procedures for heat and electricity production have been developed in the commercial and industrial sectors and focusing on the cogeneration systems, and the contribution of nuclear energy has been increased for improving processes. Nuclear reactors play an essential role in nonelectric applications, and combined heat and energy at different operating temperatures can be... 

Water is the most abundant liquid on Earth, but only 2.5% of worldwide water are fresh. It is impossible to ignore the importance of water in almost every process on Earth, from the smallest bacteria life to the formation of the continents. Today, efforts for the desalination of seawater and brackish water are critical to produce drinking water. In recent years, a novel material: hydrogel, was considered in desalination processes. Interesting hydrogel applications were proposed for forward osmosis desalination, solar still, electrodialysis, and capacitive desalination. Simple and inexpensive desalination ways for drinking water production are needed. Hydrogel compounds are one of the leading... 

The Supply of sustainable freshwater has turned into a fundamental problem in numerous countries. The increment in population, the industrialization of the world, and variation in global warming temperatures lead to an increase in droughts, storms, and floods around the world. Therefore, the problems of water scarcity appear worldwide. Contrary to popular belief, the largest reserves of water are available in the air. Accordingly, several technologies have been developed for the production of drinking water from humid air in the research works. But, the critical problem is the high energy consumption in this equipment. Therefore, the issues of water-energy nexus are the particular subject in... 

Nowadays, energy supply is one of the most prominent demands of countries in the world. The enhancement in energy efficiency, flexibility for applications in various industrial processes, and the reduction in the environmental impacts of pollutant emissions can be accomplished by using sustainable energy sources. Alternative procedures for heat and electricity production have been developed in the commercial and industrial sectors and focusing on the cogeneration systems, and the contribution of nuclear energy has been increased for improving processes. Nuclear reactors play an essential role in nonelectric applications, and combined heat and energy at different operating temperatures can be... 

Over the years, detecting stable communities in a complex network has been a major challenge in network science. The global and local structures help to detect communities from different perspectives. However, previous methods based on them suffer from high complexity and fall into local optimum, respectively. The Four-Stage Algorithm (FSA) is proposed to reduce these issues and to allocate nodes to stable communities. Balancing global and local information, as well as accuracy and time complexity, while ensuring the allocation of nodes to stable communities, are the fundamental goals of this research. The Four-Stage Algorithm (FSA) is described and demonstrated using four real-world data... 

The present study aims at the investigation of free vibration analysis of thin cylindrical shells surrounded by an elastic medium, which is distributed over a particular length of the shell. The Love’s shell theory is utilized along with the Winkler foundation to obtain the governing equations of motion. An exact series expansion method of solution is employed for any arbitrary boundary conditions. The excellent accuracy of the obtained results is validated by comparing to the available literature. Moreover, several case studies are performed to provide an insight into the influence of some practically important parameters on free vibrations of circular cylindrical shells, including... 

In the present study, free vibrations and stability of rotating single walled carbon nanotubes (SWCNT) is investigated by nonlocal theory of elasticity; while the CNT is partially resting on an elastic foundation. The governing equations of motion are presented by using Love's shell assumptions. An exact series expansion method of solution is employed and very accurate results are obtained. Some parameter studies including the effects of rotating speed, foundation stiffness, slenderness ratio and nonlocal parameter on the natural frequency and stability margins of the current model are studied. The studies show that rotation rates and foundation elasticity can contribute significantly in the... 

A moving bed biofilm reactor with pre-denitrification configuration was fed with a synthetic wastewater containing high chemical oxygen demand (COD) and ammonia. By changing different variables including ammonium and COD loading, nitrification rate in the aerobic reactor and denitrification rate in the anoxic reactor were monitored. Changing the influent loading was achieved via adjusting the inlet COD (956-2,096 mg/L), inlet ammonium (183-438 mg/L), and hydraulic retention time of the aerobic reactor (8, 12, and 18 hours). The overall organic loading rate was in the range of 3.60-17.37 gCOD/m2·day, of which 18.5-91% was removed in the anoxic reactor depending on the operational conditions....