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Reducing ion migration in methylammonium lead tri-bromide single crystal via lead sulfate passivation
, Article Journal of Applied Physics ; Volume 127, Issue 18 , April , 2020 ; Parikh, N ; Kumari, H ; Pandey, M. K ; Kumar, M ; Prochowicz, D ; Kalam, A ; Tavakoli, M. M ; Yadav, P ; Sharif University of Technology
American Institute of Physics Inc
2020
Abstract
Surface passivation of organic-inorganic halide perovskites (OIHPs) is a crucial step to annihilate the surface defects and to control the deteriorated ion migration phenomenon. Here, we study the role of lead sulfate (PbSO4) as an effective passivator in OIHP single crystals (SCs). Using impedance spectroscopy, we evaluate the ion migration and electrical properties of lead sulfate-passivated methylammonium lead tri-bromide (MAPbBr3) SCs. We found that the low-frequency impedance response that is assigned to the ionic motion in the MAPbBr3 SC is strongly affected by the inorganic PbSO4 surface treatment. The activation energy corresponding to the ion migration of MAPbBr3 SC is increased...
Elevated-temperature behaviour of LiNi0.5Co0.2Mn0.3O2 cathode modified with rGO-SiO2 composite coating
, Article Journal of Alloys and Compounds ; Volume 843 , 2020 ; Khalili Azar, M ; Esmaeili, M ; Tanhaei, M ; Dolati, A ; Hosseini H, S. M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
An intense decrease in cycling performance and safety is a challenge for elevated temperature application of LiNi0.5Co0.2Mn0.3O2 (NCM) cathode material. In this paper, effect of two types of nano-coatings on improvement of elevated temperature performance of NCM cathode material has been investigated. One of the coatings contains SiO2 nanoparticles and the other one contains composite of reduced graphene oxide and SiO2 nanoparticles (rGO-SiO2). The coatings were fabricated by a facile wet chemical method. The SiO2 coated cathode material showed an excellent elevated temperature cycling stability, however, a decrease in discharge capacity and rate capability of this sample was observed. On...
Mechanical strength of CFRP and GFRP composites filled with APP fire retardant powder exposed to elevated temperature
, Article Fire Safety Journal ; Volume 115 , 2020 ; Majdabadi Farahani, E ; Yekrangnia, M ; Ozbakkaloglu, T ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Ammonium polyphosphate (APP) is one of the most widely used halogen-free flame retardant, added in various resins to improve the fire properties, such as flame and smoke spread ratings and LOI, of fiber-reinforced polymer (FRP) composites. This paper experimentally investigates the effects of using APP, as a fire-retardant filler, on mechanical properties (i.e. ultimate tensile, flexural, and bond strength) of glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP) composites. Based on two fiber types (i.e. carbon and glass) and three different APP mass fractions in resin (i.e. 0, 20, and 40% of total weight of matrix), six sets of specimens were prepared for each...
Particle filtering-based low-elevation target tracking with multipath interference over the ocean surface
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 56, Issue 4 , 2020 , Pages 3044-3054 ; Taheri, A ; Cecen, T ; Celik, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
As radar signals propagate above the ocean surface to determine the trajectory of a target, the signals that are reflected directly from the target arrive at the receiver along with indirect signals reflected from the ocean surface. These unwanted signals must be properly filtered; otherwise, their interference may mislead the signal receiver and significantly degrade the tracking performance of the radar. To this end, we propose a low-elevation target tracking mechanism considering the specular and diffuse reflection effects of multipath propagation over the ocean surface simultaneously. The proposed mechanism consists of a state-space model and a particle filtering algorithm and promises...
Casing failure in salt rock: numerical investigation of its causes
, Article Rock Mechanics and Rock Engineering ; Volume 53, Issue 9 , 2020 , Pages 3903-3918 ; Pak, A ; Sharif University of Technology
Springer
2020
Abstract
Numerous cases of casing failure have been reported worldwide. Depletion-induced compaction is one of the main factors that may cause casing failure. Stress perturbation in salt layers may accommodate rock flow which endangers the stability of cased wells. Besides, poor cementing jobs are recognized as one of the wellbore instability causes. These factors need to be considered to determine the mechanism behind the casing failure. In this study, the creep behavior of the caprock salt layer in the southwest Iranian oil fields is experimentally studied through a number of creep tests under conditions of elevated temperature and pressure. Then, a three-dimensional finite element analysis is...
Microstructure and mechanical properties of Al-20Si-5Fe-2X (X = Cu, Ni, Cr) alloys produced by melt-spinning
, Article Materials Science and Engineering A ; Volume 492, Issue 1-2 , 2008 , Pages 443-449 ; 09215093 (ISSN) ; Simchi, A ; Davami, P ; Sharif University of Technology
2008
Abstract
Al-20Si-5Fe-2X (X = Cu, Ni and Cr) ribbons were produced by melt-spinning and consolidated by hot pressing at 400 °C for 60 min. The microstructure of the ribbons and the consolidated alloys was investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) method, and transmission electron microscopy (TEM). The hardness and compressive strength of the specimens at ambient and elevated temperatures were examined. The microstructure of the ribbons exhibited featureless and dendritic zones. Results of XRD and TEM showed formation of spherically shaped Si particles with an average diameter of 20 nm. Ultrafine Si (110-150 nm) and iron-containing...
Surveillance radar target detection with the fourier-hough transform
, Article 2008 International Radar Symposium, IRS, Wroclaw, 21 May 2008 through 23 May 2008 ; 2008 ; 9788372076212 (ISBN) ; Moqiseh, A ; Nayebi, M. M ; Sharif University of Technology
2008
Abstract
In a typical surveillance radar, decision about the existence of a target in certain range-azimuth-elevation cell is made from the echo received in current scan, while still there is useful information in history of that range cell that is not considered in decision making. Based on the potential of the Hough Transform to use history of both range and Doppler information, a new method to increase the probability of detection in surveillance radars is proposed. The new method uses a 3D data space and a special projection to detect targets and extract range, speed, and acceleration of maneuvering targets simultaneously
Processing of Al-20Si-5Fe-2X(X=Cu, Ni, Cr) alloys by melt-spinning and hot-pressing
, Article European International Powder Metallurgy Congress and Exhibition, Euro PM 2008, Mannheim, 29 September 2008 through 1 October 2008 ; Volume 2 , 2008 , Pages 99-104 ; 9781899072033 (ISBN) ; Simchi, A ; Davami, P ; Sharif University of Technology
European Powder Metallurgy Association (EPMA)
2008
Abstract
Al-20Si-5Fe-2X (X=Cu, Ni, Cr) ribbons were produced by melt-spinning and consolidated by hot pressing at 400°C for 60 min. Optical and transmission electron microscopy (TEM), X-ray diffractometry (XRD), and hardness test were used to evaluate the microstructure and mechanical strength of the ribbons and hot consolidated specimens. The compressive strength of the specimens at ambient and elevated temperatures was also examined. The microstructure of the ribbons exhibited featureless and dendritic zones, and contains spherically-shaped Si particles with an average diameter of 20 nm. After hot-pressing, ultrafine Si (110-150 nm) and iron-containing intermetallic particles were formed. The...
Numerical simulation of free-surface waves and wave induced separation
, Article Scientia Iranica ; Volume 15, Issue 3 , 2008 , Pages 323-331 ; 10263098 (ISSN) ; Mousaviraad, S. M ; Firoozabadi, B ; Ahmadi, G ; Sharif University of Technology
Sharif University of Technology
2008
Abstract
The present study is concerned with the numerical simulation of free-surface waves and wave induced separation in the presence of an intrusion. The results of several simulations are reported. The first study was performed for a NACA0024 surface piercing hydrofoil over a range of several Froude numbers (0.19, 0.37, 0.55), along with wave breaking at Fr = 1.0 The NACA0024 foil was of particular interest, as it almost has no separation at large depths; thus the effect of the free-surface wave and the wave induced separation could be studied. Free- surface waves and wave induced separation results were evaluated and compared with both the available experimental data and the previous numerical...
Near-optimal terrain collision avoidance trajectories using elevation maps
, Article 2006 IEEE Aerospace Conference, Big Sky, MT, 4 March 2006 through 11 March 2006 ; Volume 2006 , 2006 ; 1095323X (ISSN); 0780395468 (ISBN); 9780780395466 (ISBN) ; Abbasi, A ; Sharif University of Technology
2006
Abstract
The main attempt of this paper is to present a new methodology to model a generic low-level flight close to terrain, which guarantees terrain collision avoidance. Benefiting the advantages of high-speed computer technology, this method uses satellite elevation maps to generate so called 'Quad-tree forms'. The latter is then used to find the optimal trajectories for low-level flights. The novelty of this approach, entitled the 'cost map', lies in the integration of aircraft dynamics into the segmented map. This procedure results in some near-optimal trajectories with respect to aircraft dynamics that could easily be used for minimization of flight path together with pilot effort. Different...
Vibrations and stability analysis of double current-carrying strips interacting with magnetic field
, Article Acta Mechanica ; Volume 232, Issue 1 , 2021 , Pages 229-245 ; 00015970 (ISSN) ; Firouz Abadi, R. D ; Sharif University of Technology
Springer
2021
Abstract
Interactive vibrations and buckling of double current-carrying strips (DCCS) are investigated in this study. Considering the rotational and transverse deformation of the strip, four coupled equations of motion are obtained using Hamilton’s principle. Using the Galerkin method, mass and stiffness matrices are extracted and the stability of the system is determined by solving the eigenvalue problem. Effects of pretension and elevated temperature on the stability of DCCS are studied for three types of materials and various arrangements. Finally, the effect of horizontal or vertical distance between strips on the critical current value is investigated. According to the results, the effects of...
Comparison and assessment of spatial downscaling methods for enhancing the accuracy of satellite-based precipitation over Lake Urmia Basin
, Article Journal of Hydrology ; Volume 596 , 2021 ; 00221694 (ISSN) ; Hessels, T ; Moghim, S ; Afshar, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Estimating precipitation at high spatial-temporal resolution is vital in manifold hydrological, meteorological and water management applications, especially over areas with un-gauged networks and regions where water resources are on the wane. This study aims to evaluate five downscaling methods to determine the accuracy and efficiency of which on generating high-resolution precipitation data at annual and monthly scales. To establish precipitation-Land surface characteristics relationship, environmental factors, including Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST) and Digital Elevation Model (DEM), were considered as proxies in the spatial downscaling...
Enhanced electrochemical performance and thermal stability of ZrO2- And rGO-ZrO2-Coated Li[Ni0.8Co0.1Mn0.1]O2Cathode material for Li-Ion batteries
, Article ACS Applied Energy Materials ; Volume 4, Issue 1 , 2021 , Pages 934-945 ; 25740962 (ISSN) ; Razmjoo Khollari, M. A ; Esmaeili, M ; Heidari, E ; Hosseini Hosseinabad, S. M ; Siavash Moakhar, R ; Dolati, A ; Ramakrishna, S ; Sharif University of Technology
American Chemical Society
2021
Abstract
LiNi0.8Co0.1Mn0.1O2 (NCM811) has been considered as a promising cathode for Li-ion batteries (LIBs) due to its high electrochemical capacity and low cost; however, poor cycling stability is one of the main restricting factors in industrial applications of the NCM811 cathode material. Notably, the capacity fading and low structural stability of NCM811 are intensified at elevated temperatures. ZrO2- and composite rGO-ZrO2-coated NCM811 were fabricated by a facile wet chemical method and evaluated at 25 and 55 °C to overcome these impediments. The ZrO2 coating provides superior cycling and thermal stability and perfectly protects the cathode active material from deleterious side reactions, and...
Strength of SCLC recycle springs and fibers concrete subject to high temperatures
, Article Structural Concrete ; 2021 ; 14644177 (ISSN) ; Toufigh, V ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
In this article, the self-compacting lightweight concretes (SCLC) with different fibers were prepared and exposed to elevated temperatures, and their mechanical properties were investigated. Three types of fibers were steel fibers (SF), polypropylene fibers (PPF), and metal springs with a volume fraction of 0.4%. One hundred and fifty cylindrical specimens were prepared, and the compression, tensile and flexural tests were carried out on them after exposure to high temperatures ranging from 25 to 700°C. The findings indicate that incorporation of steel fibers and springs enhanced the compressive strength of concrete by 20% compared to the control specimen. Meanwhile, the polypropylene fibers...
Effect of elevated temperatures on the compressive behavior of timber filled steel and pultruded GFRP tubes
, Article Composite Structures ; Volume 271 , 2021 ; 02638223 (ISSN) ; Yekrangnia, M ; Biniaz, A ; Raftery, G. M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study examines the use of timber as a filler material for steel and pultruded GFRP tube elements and the performance of these sections is compared to solid timber columns, hollow steel and hollow pultruded GFRP tube element after exposure to elevated temperature. In total, 102 specimens were fabricated and exposure to elevated temperature ranging from 20 to 700 °C was evaluated. It was found out that filled tubes using timber could improve the compressive strength and stiffness of tubular section specimens up to 73 and 212 percent, respectively. Timber filled steel tube (TFST) and hollow steel tube specimens had a better performance at elevated temperature in comparison to other...
Comparative study on the effect of fiber type and content on the fire resistance of alkali-activated slag composites
, Article Construction and Building Materials ; Volume 288 , 2021 ; 09500618 (ISSN) ; Ghassemi, P ; Ameri, F ; Musaeei, H. R ; Chee Ban, C ; Ozbakkaloglu, T ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Alkali-activated slag (AAS) binder has been recognized as a suitable material for construction applications owing to its low carbon footprint and good mechanical and durability performance. As a promising alternative to the conventional Portland cement binder, it is important to maximize the performance of AAS composites under normal and harsh environmental conditions such as exposure to fire. The use of fibers in a brittle matrix is a well-known approach to enhance the mechanical strength and cracking behavior under thermal loading. In this study, polypropylene fiber (PPF), glass fiber (GF), and basalt fiber (BF) are used at volume fractions of 0.5%, 1%, and 1.5% in AAS mortar mixes. First,...
The effects of elevated temperatures on the performance of concrete-filled pultruded GFRP tubular columns
, Article Thin-Walled Structures ; Volume 169 , 2021 ; 02638231 (ISSN) ; Khaloo, A ; Azizmohammadi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Usage of concrete-filled pultruded glass fiber-reinforced polymer (GFRP) tubes (CFPGT) as columns can increase the service life of structures. However, marine structures such as oil platforms are always prone to fire because of the low resistance to the elevated temperatures. The purpose of this investigation is to evaluate the effects of concrete core strength (30 and 60 MPa), and exposure temperature (25, 100, 200, 300, and 400 °C) and time (60 and 120 min) on the compressive and bond behavior of CFPGTs. The properties of unexposed and exposed concrete core, pultruded GFRP hollow tubes, and CFPGTs were determined via compressive and disk-split tests. Also, the push-out test was used to...
Formability of tri-layered IF240/AZ31/IF240 composite with strong bonding: experimental and finite element modeling
, Article Journal of Materials Engineering and Performance ; Volume 30, Issue 11 , 2021 , Pages 8402-8411 ; 10599495 (ISSN) ; Akbarzadeh, A ; Hadiyan, B ; Hashemi, R ; Sharif University of Technology
Springer
2021
Abstract
In this work, the formability of a hybrid material of Interstitial-Free 240 (IF240) steel and AZ31 magnesium alloy as IF240/AZ31/IF240 tri-layered sheets was investigated. For this purpose, the bonding feasibility of the high-formability IF240 steel and low-formability AZ31 sheets was first assessed. Then, the hot formability behavior of the manufactured laminated composite was evaluated. The rolling of the preheated samples established the layer bonding. The bonding strength was determined using the shear punch test. The texture and its effects on the forming behavior were studied using the x-ray Goniometry method. Nakazima dome tests were employed at ambient and elevated temperatures to...
Formability of Tri-layered IF240/AZ31/IF240 composite with strong bonding: Experimental and finite element modeling
, Article Journal of Materials Engineering and Performance ; Volume 30, Issue 11 , 2021 , Pages 8402-8411 ; 10599495 (ISSN) ; Akbarzadeh, A ; Hadiyan, B ; Hashemi, R ; Sharif University of Technology
Springer
2021
Abstract
In this work, the formability of a hybrid material of Interstitial-Free 240 (IF240) steel and AZ31 magnesium alloy as IF240/AZ31/IF240 tri-layered sheets was investigated. For this purpose, the bonding feasibility of the high-formability IF240 steel and low-formability AZ31 sheets was first assessed. Then, the hot formability behavior of the manufactured laminated composite was evaluated. The rolling of the preheated samples established the layer bonding. The bonding strength was determined using the shear punch test. The texture and its effects on the forming behavior were studied using the x-ray Goniometry method. Nakazima dome tests were employed at ambient and elevated temperatures to...
Physico-mechanical properties and micromorphology of AAS mortars containing copper slag as fine aggregate at elevated temperature
, Article Journal of Building Engineering ; Volume 39 , 2021 ; 23527102 (ISSN) ; Shoaei, P ; Zahedi, M ; Karimzadeh, M ; Musaeei, H. R ; Cheah, C. B ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Copper slag (CS) is an industrial by-product, which is commonly disposed in engineered landfills. Prior studies have successfully incorporated CS as an aggregate phase in cementitious materials. However, the alkali-activated material (AAM) incorporating CS has been scarcely studied. Specifically, the elevated temperature behavior of AAM with CS has not been investigated previously. The present paper aims to study the effects of elevated temperature treatment on the mass loss and residual strength of alkali-activated slag mortars incorporating 0–100% (by volume) of CS with an incremental step of 20% instead of natural sand. The mass loss, compressive and flexural strengths, and microstructure...