Sharif Digital Repository

The floating photovoltaic (FPV) array, which consists of tens or hundreds of rows of floating photovoltaic systems, exhibits great economic and environmental benefits. An FPV array arranged in the ocean will be subjected to the combined action of wind, waves, and currents during the installation, service, and maintenance processes; however, systematic research in this field is still lacking. As a representative of the FPV array, this study on the hydrodynamic characteristics of a single-row FPV system is a fundamental prerequisite for the safe design of large-scale FPV arrays in the near future. In this paper, based on the potential theory, a numerical model of a single-row FPV system with... 

The present work describes sensing application of modified TiO 2 nanotubes having carbon-Pt nanoparticles for simultaneous detection of dopamine and uric acid. The TiO 2 nanotubes electrode was prepared using anodizing method, followed by electrodeposition of Pt nanoparticles onto the tubes. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. The C-Pt-TiO 2 nanotubes modified electrode was characterized by cyclic voltam-metry and differential pulse voltammetry methods. The modified electrode displayed high sensitivity towards the oxidation of dopamine and uric acid in a phosphate buffer solution (pH 7.00). The electro-oxidation currents... 

In this study a novel Pt/Ni nanostructure consisting of nano-bushes and nanocubes was fabricated onto TiO 2 nanotubes. The scanning electron microscopy images showed that a large amount of well-dispersed nano-architectures had uniformly covered all over the surface which made an electrode with high surface area. It was obviously seen that the nanocube structures mainly consists of Ni had been grown on top of each other while the Pt colonies represented bush-like structures. As a non-enzymatic glucose biosensor, the Pt/Ni TiO 2 nanotubes modified electrode exhibited an excellent performance. The proposed biosensor had two linear ranges for detection of glucose from 0 to 0.12 mM (correlation... 

An electro-catalysis non-enzymatic electrode is proposed based on alloyed Pt/Ni nanowire arrays (NWAs) for the detection of glucose. The Pt/Ni NWAs were prepared by pulse electrodeposition of Pt and Ni within a nano-pore polycarbonate (PC) membrane followed by a chemical etching of the membrane. The electrode structure is characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resulting Pt/Ni NWAs electrode shows high electrocatalytic activities towards the oxidation of glucose in alkaline solution. Consequently, a sensitive amperometric detection of glucose is achieved under 0.45 V vs. SCE with a low detection limit of 1.5 μM within a wide linear... 

A nanowire arrays system consisting of an ordered configuration of Pt, Ni and Co was constructed in single-bath solution through pulse electrodeposition. This structure was evaluated as a potential amperometric non-enzymatic sensor to detect glucose in alkaline solution. We observed a strong and fast amperometric response at low applied potential of 0.4 V vs. SCE over linear ranges of 0-0.2 mM and 0.2-8 mM glucose with sensitivities of 1125 and 333 μA mM-1 cm-2, respectively. We also observed a low detection limit for glucose of 1 μM. Correlation of the electronic and geometric modifications with the electrochemical performance characteristics enhanced catalytic activity of the electrode by... 

We consider a problem of localizing a temporal path signal that evolves over time on a graph. A path signal represents the trajectory of a moving agent on a graph in a series of consecutive time stamps. Through combining dynamic programing and graph partitioning, we propose a path-localization algorithm with significantly reduced computational complexity. To analyze the localization performance, we use two evaluation metrics to quantify the localization error: The Hamming distance and the destination's distance between the ground-truth path and the estimated path. In random geometric graphs, we provide a closed-form expression for the localization error bound, and a tradeoff between... 

A simple modified TiO2 nanotubes electrode was fabricated by electrodeposition of Pd, Pt and Au nanoparticles. The TiO2 nanotubes electrode was prepared using the anodizing method, followed by modifying Pd nanoparticles onto the tubes surface, offering a uniform conductive surface for electrodeposition of Pt and Au. The performance of the modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry methods. The Au/Pt/Pd/TiO2 NTs modified electrode represented a high sensitivity towards individual detection of dopamine as well as simultaneous detection of dopamine and uric acid using 0.1 M phosphate buffer solution (pH 7.00) as the base solution. In both case,... 

The catalytic activity of Pt/Ni/TiO 2 nanotubes electrode toward glucose has been studied. Fabrication of Pt/Ni nanostructures was done in a single-bath solution through electrochemical pulse method by changing the deposition potential between -0.3 and -4 V vs. SCE, respectively. The resulting modified electrode represented high conductivity due to the effective presence of metallic components and uniform surface area caused by dispersion of Pt and Ni nanostructures. The scanning electron microscopy images also confirmed that a large amount of metals colonies were well-dispersed at the edge of the TiO 2 nanotubes. In addition, the Pt/Ni TiO 2 nanotubes modified electrode exhibited an... 

As the increasing demands of military detection, wireless communication and remote sensing make the spectrum even more crowded, radar sequence design meeting spectral compatibility requirement is a challenging and urgent problem. This study is devoted to designing optimised phase-coded sequences which keep spectral-compatible with the overlaid electromagnetic radiators and at the same time optimise the signal-to-interference-plus-noise ratio (SINR). First, an intelligent dynamic spectrum information around the radar system is achieved by a radio environmental map. The information is introduced to form a constrained optimisation process aimed at improving the spectral compatibility and the... 

Ternary hybrid nanofluids possess improved thermal characteristics, enhanced stability, better physical strength, and multi-functionality as compared to hybrid or usual nanofluids. The aim of the ongoing study is to explore the novel thermal attributes of hybrid and trihybrid nanofluids through a porous medium. Whereas the nano-composition of cobalt (Co), gold (Au), and zirconium oxide (ZrO2) make amalgamation in the paraffin (Pfin) which is a base fluid. This nano-composition of the proposed nanoparticles, specifically, subject to the base fluid Pfin has not been interpreted before. The analysis not only covers the features of trihybrid nanofluids (Co-Au-ZrO2-Pfin) but it also describes the... 

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... 

The effect of bisulfite (HSO3–) in nCaO2/Fe(III)/HSO3– system on improving HO• generation and trichloroethene (TCE) removal was innovatively reported. The enhancement mechanism of HSO3– for TCE removal in nCaO2/Fe(III)/HSO3– system was caused not only by the complexing and reducing effects on promoting the conversion of Fe(III) to Fe(II), but also due to the reaction with O2 in water to produce SO4–• for accelerating TCE degradation. A double effect of nCaO2 as an oxidant source to generate HO• and as a O2 source to promote SO4–• generation was revealed. A pseudo-second-order kinetic model of TCE removal was determined and 94.6% TCE degradation was achieved within 60 min at the... 

Nickel oxide (NiOx) is a promising hole transport material in inverted organic-inorganic metal halide perovskite solar cells. However, its low intrinsic conductivity hinders its further improvement in device performance. Here, we employ a trimercapto-s-triazine trisodium salt (TTTS) as a chelating agent of Ni2+ in the NiOx layer to improve its conductivity. Due to the electron-deficient triazine ring, the TTTS complexes with Ni2+ in NiOx via a strong Ni2+-N coordination bond and increases the ratio of Ni3+:Ni2+. The increased Ni3+ concentration adjusts the band structure of NiOx, thus enhancing hole density and mobility, eventually improving the intrinsic conductivity of NiOx. As a result,... 

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... 

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... 

Hydroxyapatite (HA) coatings were deposited on commercially pure titanium plates using a hydrothermal-electrochemical deposition method in an electrolyte containing calcium and phosphate ions. The deposition conditions used in this study were the followings: electrolyte temperature (33-80 °C), current density (1-8 mA/cm2), and deposition time (10-120 min). Needle-like and granular crystals of apatite coating were created with different concentrations of calcium (0.0021-0.042 M) and phosphate (0.00125-0.025 M) salts. The size of HA crystals of the coating was considerably changed with different concentration of calcium and phosphate salts, temperature of the electrolyte, and deposition time.... 

Because of the compatibility with tandem devices and the ability to be manufactured at low temperatures, inverted perovskite solar cells have generated far-ranging interest for potential commercial applications. However, their efficiency remains inadequate owing to various traps in the perovskite film and the restricted hole blocking ability of the electron transport layer. Thus, in this work, a wide-bandgap n-type semiconductor, 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-phenylpyrimidine (B4PyPPM), to modify a perovskite film via an anti-solvent method is introduced. The nitrogen sites of pyrimidine and pyridine rings in B4PyPPM exhibit strong interactions with the undercoordinated lead ions in... 

Catalytic activity of carbon/Pt nanoparticles modified TiO 2 nanotubes electrode was studied by using dopamine contained solutions. The TiO 2 nanotubes electrode was prepared using anodizing method in aqueous solution. The electrochemical pulse method was then applied for electrodeposition of Pt nanoparticles onto the TiO 2 nanotubes. Further modification was achieved by decomposition of polyethylene glycol in a tube furnace to have a carbon/Pt nanoparticles modified TiO 2 nanotubes electrode. The final modified electrode could successfully detect the electro-oxidation of dopamine in a ImM contained solution using cyclic voltametry method. Also, a high sensitivity towards the oxidation of... 

The effect of moisture on Shengli lignite breakage behavior and energy efficiency was studied experimentally using a standard Hardgrove mill fitted with a wattmeter. The grinding process concerned both the inputs, namely the occurrence and content of water and instantaneous energy consumption and the outputs, size-reduction and product fineness. Results show that the energy-size reduction process for grinding lignite is markedly influenced by moisture occurrence and content. Removing surface moisture from 37.90% to 16.61% (the air-dried condition) resulted in a slight increase of input energy by 0.04 kWh.t−1 per 10 s. However, with further drying inherent moisture to 0%, the consumed energy... 

Considering the interaction of flexural moment and shear force in the steel frames with haunch or intermediate beam length and eccentrically braced frames with intermediate link length is a major concern of the structural analysis and design. This article contains two stages. In the first stage, to investigate the moment–shear interaction for the highly ductile steel I-sections, a study is carried out using finite element analysis and a simple and practical relationship is developed. In the second stage, a simple approach based on virtual work method for assemblage of interconnected rigid bodies is employed to consider collapse mechanisms with mixed hinges. Using this approach, the...