Sharif Digital Repository

Objectives. This article describes the reduction of unsafe behaviors observed at a fertilizer complex by implementation of a behavior-based safety (BBS) program via a behavior observation form developed by a multidisciplinary team. Methods. Six observation categories, i.e., position of people, reaction of people, personal protective equipment (PPE), tools used, operating procedures and housekeeping, are used to monitor safe and unsafe behaviors for a period of 18 months. Results. Safe behaviors increased from 57 to 70% and unsafe behaviors reduced from 40 to 26%. Behaviors of employees working in various sections of fertilizer complex such as ammonia, urea, utility, bagging/shipping and... 

Metamaterials are manmade structures that have attained considerable attention over the past 2 decades in the modern fields like cloaking, sensing, and imaging owing to their ability to harness electromagnetic fields. In this regard, we have inspected the dielectric properties of the hyperbolic metamaterials (HMM) made of metallic nanorods and dielectric medium at the infrared wavelength regime. The periodically arranged subwavelength-sized metallic nanorods embedded in the silicon dioxide (SiO 2) substrate glass. The spacing between two adjacent nanorods is of subwavelength in size. Furthermore, effective permittivity of the metamaterial has been analyzed by employing the Maxwell Garnett... 

Based on exclusive thermal dynamic of nanomaterials, various applications are noted in engineering and industrial processes. Owing to such thermal impact, the researchers have presented comprehensive research on nanomaterials. While claiming novel applications of nanofluids, the stability of nanomaterials is important for which less attention has been paid. On this end, the aim of current research is to predict the thermal instability of graphene nanoparticles with suspension of water base fluid due to transient Hartmann flow. The Poiseuille flow of water-based nanoparticles subject to the magnetic force is assumed between two plates. The numerical outcomes are predicted with implementation... 

Indium substituted Cu[sbnd]Ni nanoferrites with nominal compositions Cu 0.5 Ni 0.5 In x Fe 2-x O 4 (x = 0.00–0.32)were successfully synthesized by sol-gel auto ignition method. X-ray diffraction patterns illustrated the single phase spinel structure for x ≤ 0.24. The lattice parameter ‘a’ increased from 8.3349 to 8.3723 Å and then it decreased for x = 0.32. X-ray density increased from 5.43 to 5.79 g/cm 3 . The average crystallite sizes lie in the range 33.21–17.78 nm. The cell volume was increased from 579.03 to 586.86 Å 3 with the substitution of indium ions into the spinel lattice of copper nickel ferrites. The compositional dependence of tetrahedral and octahedral radii was explained on... 

The hybrid power system is a combination of renewable energy power plants and conventional energy power plants. This integration causes power quality issues including poor settling times and higher transient contents. The main issue of such interconnection is the frequency variations caused in the hybrid power system. Load Frequency Controller (LFC) design ensures the reliable and efficient operation of the power system. The main function of LFC is to maintain the system frequency within safe limits, hence keeping power at a specific range. An LFC should be supported with modern and intelligent control structures for providing the adequate power to the system. This paper presents a... 

The mixed nano-ferrites materials Cu0.6Zn0.4HoxFe2−xO4 (0.00 ≤ x ≤ 0.12) were prepared via the sol–gel auto combustion technique. The TGA curve established the annealing temperature (500 °C) for phase formation. The single exothermic peak on the DSC plot occurred at 341 °C temperature. XRD patterns of these nano ferrites verified single phase formation of the FCC cubic structure. The lattice constant a was increased from 8.4244 to 8.4419 Å and then its value decreased to 8.4319 Å. Crystallite size was found in the range of 7 to 16 nm. The surface morphology of the samples was observed from the scanning electron microscope (SEM) images. The grain size was found within the range of 90 nm to... 

The mixed nano-ferrites materials Cu0.6Zn0.4HoxFe2−xO4 (0.00 ≤ x ≤ 0.12) were prepared via the sol–gel auto combustion technique. The TGA curve established the annealing temperature (500 °C) for phase formation. The single exothermic peak on the DSC plot occurred at 341 °C temperature. XRD patterns of these nano ferrites verified single phase formation of the FCC cubic structure. The lattice constant a was increased from 8.4244 to 8.4419 Å and then its value decreased to 8.4319 Å. Crystallite size was found in the range of 7 to 16 nm. The surface morphology of the samples was observed from the scanning electron microscope (SEM) images. The grain size was found within the range of 90 nm to... 

In the energy system, various sources are used to fulfill the energy demand of large buildings. The energy management of large-scale buildings is very important. The proposed system comprises solar PVs, energy storage systems, and electric vehicles. Demand response (DR) schemes are considered in various studies, but the analysis of the impact of dynamic DR on operational cost has been ignored. So, in this paper, renewable energy resources and storages are integrated considering the demand response strategies such as real-time pricing (RTP), critical peak pricing (CPP), and time of use (ToU). The proposed system is mapped in a linear model and simulated in MATLAB using linear programming... 

Electrical energy is very necessary for human life in the modern era. The rising energy prices, depletion of fossil fuels, and instability of the grid are alarming situations. So, it needs a smart solution to ensure the balance between pricing and saving natural resources. Some other issues like environmental change, limitations on installation of new transmission lines, reliability concerns, and considering the expansion in distributed energy generation technologies promise the implementation of distributed generation extensively. The integration of two or more energy supplies in a power system is known as distributed energy resource system. In this study, a university campus is taken as a... 

This study describes a novel approach to design of a power factor correction (PFC) and total harmonic distortion (THD) reduction-based brushless DC (BLDC) motor drive. The drive was designed to obtain a reduced THD for PFC. The basic design of the BLDC motor drive contains an AC voltage source as input for a diode bridge rectifier. The output DC voltage is filtered out to reduce ripples. The smooth DC output voltage is supplied to the modified Zeta converter. The output voltage of the modified Zeta converter is controlled by using pulse width modulation (PWM). The modified Zeta converter is utilized in discontinuous inductor current mode (DICM) for better power factor. This controlled DC... 

Heat transport features of a dusty fluid flow within a resistive porous medium are numerically interpreted under the magnetohydrodynamic environment. Fluid and dust phase characteristics are overlooked against the preeminent parameters. The main concern, in this work, is to analyze how much the resistive porous media affects the dusty flow in the presence of Lorentz force. The use of convection boundary conditions will aid attain the desired heat transfer rate in engineering applications. The nonlinear partial differential equations governing the fluid and dust phase are transmuted into a system of coupled and highly nonlinear ordinary differential equations which are first discretized using... 

Currently, materials with outstanding absorption abilities, such as thin size, better absorbing power, and light weight are the need of industry to resolve the electromagnetic issues. However, the research on optimizing the composition of the material, microstructure and the structure of the absorber are also the important factors for enhancing the absorption features. A metamaterial microwave absorber (MMA) based on nano ferrites with desirable absorption peaks is proposed and simulated. Sol-gel auto combustion route is used to prepare the nanosized Sm doped Co ferrite with Co1+xSmxFe2-2xO4 at x = 0.00, 0.03, 0.06, 0.09, respectively. XRD, VSM, FESEM, and VNA were employed to evaluate the... 

Co2+ and Cr3+-substituted SrBaCu2-xCoxCryFe28-yO46 X-type hexaferrite with x = y = 0, 0.1 to 0.5 (step = 0.1) were prepared through auto-combustion sol–gel method and sintered at 1250 °C for 5 h which was found from thermal analysis. The thermal investigation, phase detection, spectral, magnetic, and dielectric characteristics of the prepared composition were investigated by TGA, XRD, FTIR, VSM, and dielectric measurement. XRD patterns of the entire composition confirmed the development of a single phase of X-type structure. The enhancement in the lattice parameters and cell volume was observed by varying the Co–Cr concentration, attributed to the larger ionic radii substitution. FTIRspectra... 

Current energy systems face multiple problems related to inflation in energy prices, reduction of fossil fuels, and greenhouse gas emissions which are disturbing the comfort zone of energy consumers and the affordability of power for large commercial customers. These kinds of problems can be alleviated with the help of optimal planning of demand response policies and with distributed generators in the distribution system. The objective of this article is to give a strategic proposition of an energy management system for a campus microgrid (µG) to minimize the operating costs and to increase the self-consuming energy of the green distributed generators (DGs). To this end, a real-time based... 

In present research six samples of nano X-type hexagonal ferrites with general formula SrBaMg2-xCoxDyyFe28-yO46 (x = 0–1; y = 0–0.1 with step size of 0.2 and 0.02, respectively) were synthesized by sol–gel technique. The temperature required for the phase formation of these materials was estimated using thermogravimetric analysis. X-ray diffraction patterns revealed the pure phase of the prepared materials up to the doping concentration of x = 0.4, y = 0.04 along with the second phase for higher doping concentration. The secondary phase appeared due to the solubility limit of higher ionic radius Dy3+ ions into the hexagonal lattice. The mean crystalline size decreased from 29 to 18 nm while... 

In this work, we study the role of nanotextured ZnFe2O4/Fe2O3composite thin films fabricated by ultrasonic spray pyrolysis (USP) on the photoelectrochemical water oxidation reactions. The ZnFe2O4/Fe2O3 composites with different molar ratios are deposited on three-dimensional nanospikes (NSP) substrate, and the results are compared with those for planar devices. It is observed that optical absorption and charge separation due to larger surface area is significantly enhanced in nanotextured photoactive ZnFe2O4/Fe2O3 films. After characterization of ZnFe2O4/Fe2O3 composite films with different molar ratios (ZF1, ZF2, and ZF3), we find that the nanotextured ZF1 composite with a molar ratio of... 

Abstract: Complex and large scale systems and networks have evolved in many fields: from communication data networks, banking, financial systems, bio-engineering and robotics to, amongst others, industrial control systems. In control engineering, the main driving force behind the expansion of large-scale complex systems has been the relatively low cost of installing advanced instrumentation hardware, the low cost of attaining high computing power and the desire to 'see' and `monitor¿ as much of the process as possible  

Recently, photoelectrochemical conversion (PEC) of water into fuel is attracting great attention of researchers due to its outstanding benefits. Herein, a systematic study on PEC of water using CuFe2O4/ α-Fe2O3 composite thin films is presented. CuFe2O4/ α-Fe2O3 composite thin films were deposited on two different substrates; (1) planner FTO glass and (2) 3-dimensional nanospike (NSP). The films on both substrates were characterized and tested as anode material for photoelectrochemical water splitting reaction. During PEC studies, it was observed that the ratio between two components of composite is crucial and highest PEC activity results were achieved by 1:1 component ratio (CF-1) of... 

We demonstrate for the first time the application of p-NiFe2O4/n-Fe2O3 composite thin films as anode materials for light-assisted electrolysis of water. The p-NiFe2O4/n-Fe2O3 composite thin films were deposited on planar fluorinated tin oxide (FTO)-coated glass as well as on 3D array of nanospike (NSP) substrates. The effect of substrate (planar FTO and 3D-NSP) and percentage change of each component (i.e., NiFe2O4 and Fe2O3) of composite was studied on photoelectrochemical (PEC) water oxidation reaction. This work also includes the performance comparison of p-NiFe2O4/n-Fe2O3 composite (planar and NSP) devices with pure hematite for PEC water oxidation. Overall, the nanostructured... 

This study demonstrates a novel, facile and one-pot approach to synthesize silica nanoparticles with silver at core and crust (SiNP-AgCC). A modified Stöber method was used to make SiNP-AgCC. A significant reduction in the size of SiO2 nanoparticles was seen, with 2–5 nm AgNPs being uniformly distributed on the surface and 10–20 nm AgNPs in the center. A typical mesoporous SiO2 particle (SiNP) produced using the Stöber method was transformed to nanoporous SiO2 by this modified Stöber method. Nanoporous SiO2 particles with silver in the center are advantageous for slow and consistent Ag+ release, which was confirmed by Ag+ ion release test. Antibacterial activities of the samples were tested...