Sharif Digital Repository

Neurological disorders and nerve injuries, such as spinal cord injury, stroke, and multiple sclerosis can result in the loss of muscle function. Electrical stimulation of the neuronal cells is the currently available clinical treatment in this regard. As an effective energy harvester, the triboelectric nanogenerators (TENG) can be used for self-powered neural/muscle stimulations because the output of the TENG provides stimulation pulses for nerves. In the present study, using a computational modelling approach, the effect of surface micropatterns on the electric field distribution, induced voltage and capacitance of the TENG structures have been investigated. By incorporating the effect of... 

Skin wounds are common in accidental injuries, surgical operations, and chronic diseases. The migration and proliferation of fibroblast cells are fundamental to wound healing, which can be promoted by electrical stimulation as a physical therapy modality. Therefore, the development of portable electrical stimulation devices that can be used by patients on-site is an essential need. In the present study, a self-cleaning triboelectric nanogenerator (TENG) has been fabricated for enhancing cell proliferation and migration. The polycaprolactone‑titanium dioxide (PCL/TiO2) and polydimethylsiloxane (PDMS) layers were fabricated via a facile method and used as the electropositive and... 

Abstract: The magnetite (Fe3O4) nanoparticles were synthesized and supported on the reduced graphene oxide. The characterization of the catalyst was performed by FT-IR, VSM, SEM, XRD, and BET techniques. The obtained results indicated that the in situ synthesis of Fe3O4 using coprecipitation method caused the homogenous formation of magnetite nanoparticles on the surface of reduced graphene oxide (average particle size ~ 71.032 nm) with high stability and catalytic activity toward electro-Fenton removal of Reactive Red 195. The effect of various factors (current intensity, initial pollutant concentration, catalyst weight, and pH) was evaluated by response surface methodology using central... 

In this paper, some important circuit parameters of a monolayer armchair graphene nanoribbon (GNR) field effect transistor (GNRFET) in different structures are studied. Also, these structures are Ideal with no defect, 1SVGNRFET with one single vacancy defect, and 3SVsGNRFET with three SV defects. Moreover, the circuit parameters are extracted based on Semi Classical Top of Barrier Modeling (SCTOBM) method. The I-V characteristics simulations of Ideal GNRFET, 1SVGNRFET and 3SVsGNRFET are used for comparing with SCTOBM method. These simulations are solved with Poisson-Schrodinger equation self-consistently by using Non- Equilibrium Green Function (NEGF) and in the real space approach. The... 

Graphene nanoribbon field effect transistors are promising devices for beyond-CMOS nanoelectronics. Graphene is a semiconductor material with zero bandgap and its bandgap must be changed. One of the opening bandgap methods is using graphene nanoribbons. By applying a defect, there is more increase on band gap of monolayer armchair graphene nanoribbon field effect transistor. So, by applying more than one defect, we can reach to much more increase in bandgap of graphene nanoribbon field effect transistors (GNRFET). In this paper, double-gated monolayer armchair graphene nanoribbon field effect transistors (GNRFET) with one single vacancy (1SV) defect (so-called 1SVGNRFET)are simulated and... 

Adaptive application detection in today's high-bandwidth networks is resource consuming and inaccurate due to the high volume, velocity, and variety characteristics of the networks traffic. To generate a robust classifier for identifying applications over encrypted traffic, we proposed DSCA as a DPI-based Stream Classification Algorithm. DSCA utilizes applications detected by the DPI, Deep Packet Inspection technique, as ground truth data and updates the classification model accordingly. To reduce the classification algorithms overhead without accuracy reduction, a feature selection method, named CfsSubsetEval, is deployed in DSCA. The proposed approach is implemented via the MOA tool and... 

CuFeO2/CeO2 as a novel synergistic catalyst for EF removal of organic pollutants was synthesized. © 2019 Elsevier Ltd  

In the present study, a novel theoretical model is developed, based on the energy method, to predict the equivalent mechanical properties of a new morphing structure with zero Poisson's ratio, which is composed of continuous fiber reinforced composite struts. Due to the employing glass fiber in fabricating the proposed cruciform honeycomb, higher strength than the structures made of pure isotropic materials is obtained. The use of cells with a zero Poisson's ratio also increases the flexural strength of the structure. In the continuation of the paper, by examining the geometric effects on the equivalent properties, a parametric study is performed. Then, using the appropriate failure... 

This study explored thermal behavior of four kinds of chromium compounds such as CrO3, K2Cr2O7, K2CrO4, and Cr2O3 using thermogravimetry (TG) and differential scanning calorimetry (DSC) method under the oxygen (O2) and nitrogen (N2) gas atmosphere at varying temperatures (25 to 1600 ℃). A diverse of chromium compounds were carefully evaluated for the first time through this method, and the present work provides new, comprehensive and valuable information regarding the mentioned compounds. XRD technique and elemental analysis were applied in order to recognize the products at diverse decomposition stages. The obtained products were then investigated via a SEM electron microscope. Also, the... 

The formation of water drops as a Newtonian fluid and formation of a shear-thinning non-Newtonian fluid, Carboxyl Methyl Cellulose (CMC) from a capillary into different bulk fluids are experimentally investigated. A high speed camera is used to visualize the images of the drops and an image-processing code employed to determine the drop properties from each image. It was found that the properties of the water drops when they are drooped into the liquids bulk fluids such as toluene and n-hexane are almost the same while they differed substantially when they were drooped into the air bulk fluid. It is shown that during the formation of water drop in all three kinds of bulk fluids, the drop... 

In the present paper, several experimental and theoretical studies conducted on the thermal conductivity of nanofluids are represented and investigated. Based on the reviewed studies, various factors affect thermal conductivity of nanofluids such as temperature, the shape of nanoparticles, concentration and etc. Results indicated the increase in temperature and concentration of nanoparticles usually leads to the higher thermal conductivity of nanofluids. In addition, it is concluded that there are some novel approaches in order to obtain nanofluids with more appropriate thermal properties including using binary fluids as the base fluid or utilizing hybrid nanofluids. © 2018 Elsevier B.V  

Iran is one of the most energy-consuming countries, especially in the construction sector, and more than 40% of its energy consumption is in the construction sector. Therefore, considering the very high potential of Iran in the field of solar energy, the need to pay attention to providing part of the energy required by buildings by solar energy seems necessary. The study of the effect of climate on the performance of a BIPV has not been done in Iran so far. Also, the use of ranking methods using the weighting of parameters affecting the performance of BIPV has not been done so far. The purpose of this study is to investigate the power supply of BIPV connected to the grid in the eight... 

The grain size of constrained groove pressed aluminum has been predicted through the genetic programming approach. “Sheet thickness,” “elongation,” “yield strength,” “ultimate tensile strength,” “total strain,” and “hardness,” along with “primary grain size” of the ultrafine-grained sheets were utilized as input parameters to obtain the ultimate grain size. A total number of 73 available data in the literature were gathered and randomly divided into 60 and 13 sets for algorithm training and testing, respectively. Among the presented models, the one with best performance utilized parameters of total strain, ultimate tensile strength, and primary grain size with 40 chromosomes, 10 head sizes,... 

The influence of liquid bulk viscosity on the dynamics of a single cavitation bubble is numerically studied via Gilmore model with a new modified boundary condition at bubble interface. In order to more accurately describe the interior gas thermodynamics, a hydrochemical model is used. The numerical results for an argon bubble in water and aqueous H2SO4 show that including the liquid bulk viscosity slightly affects the bubble dynamics in collapse phase. This effect becomes significant only at high ultrasonic amplitudes and high viscosities. Moreover, the maximum pressure value inside the bubble is much more influenced than the maximum temperature. This finding lends support to results of... 

Pulsating heat pipes are cooling devices that are partially filled with working fluid. Working fluid thermophysical properties affect the thermal performance of pulsating heat pipes. In this research, the effect of adding a Triton X-100 surfactant to pure water and using the mixture as a working fluid is investigated experimentally. The results indicate that adding surfactant leads to improvement in the thermal performance of the pulsating heat pipe. In particular, the maximum of the thermal resistance improvement is about 61%, which is attributed to 0.01% surfactant concentration. Higher heat transfer ability is attributed to lower surface tension and the contact angle of the mixture... 

The main effects of liquid compressibility on the dynamics of single bubble sonoluminescence are investigated via three different radial dynamics models. In order to precise description of the interior gas thermodynamics, a hydrochemical model is used. In the case of an argon gas bubble in water, the results obtained with the Gilmore model and the Lezzi and Prosperetti model are compared with those resulting from the Keller and Miksis model. It is shown that the variation of liquid density at bubble surface in a very short time interval around the end of the bubble collapse, which has been incorporated into the first two models, strongly influences the bubble cavitation dynamics at higher... 

Pulsating Heat Pipes (PHPs) are cooling devices that are compact in size and have an ability to transfer heat in low temperature differences. Working fluids strongly affect the thermal performance of PHPs. In this paper, effects of some thermophysical parameters relating to working fluids, such as boiling point, latent heat of vaporization, surface tension, thermal conductivity and dynamic viscosity, are presented based on experimental and numerical studies done in recent years. Addition of nanoparticles to fluids, or making nanofuild, is a new method of improving thermophysical properties of fluids. Recently, many studies are carried out on thermophysical properties of nano-fuild. Results... 

The effects of liquid density variation at the bubble surface on the dynamics of a single acoustic cavitation bubble are numerically studied. The Gilmore model together with a comprehensive hydrochemical model is used. The evaporation and condensation of water vapor are included in the hydrochemical model. The simulation results are compared to those resulting from the widely known Keller-Miksis model, which assumes a constant liquid density at the bubble surface. The numerical results for a single argon bubble in water reveal that the pressure and the temperature inside the bubble in collapse phase significantly increase, when the non-constant liquid density is used. These differences... 

Mass transfer efficiency and catalytic reactivity are the two major hurdles for heterogeneous catalytic wet peroxide oxidation (CWPO) technologies. To address these issues, nanocomposite CuFeO2/Al2O3 was synthesized and assessed as a novel catalyst for enhanced adsorption and oxidation of anionic pollutants (catechol and reactive red 195 (RR195)) in waters. With a positive charge on the nanocomposite by introducing Al2O3, the adsorption of anionic pollutants was promoted. The surface complexation reaction on CuFeO2/Al2O3, which fits well to the Langmuir isotherm, has engined the mass transfer of pollutants to the nanocatalyst that demonstrated 96.46% and 99.75% removal of catechol and RR195... 

Photovoltaic (PV) panels provide a suitable way for the direct conversion of solar energy into electricity. The electrical output and efficiency of PV modules are dependent on working temperature. The present study contributes to investigate the efficiency of utilizing a flat plate closed-loop pulsating heat pipe (CLPHP) to cool down a PV panel in both thermal and economic aspects. Accordingly, a numerical investigation is employed to obtain the surface temperature and electrical gain of the PV panel through four scenarios, including natural cooling without additional equipment, CLPHP-based passive cooling, CLPHP-based active cooling, and a conventional flat plate cooling methods. The...