G.A. Sheikhzadeh and M.A. Mehrabian
The purpose of this paper is to apply the numerical methods to study the heap leaching process in a bed of porous and spherical ore particles. This study is performed in two…
Abstract
Purpose
The purpose of this paper is to apply the numerical methods to study the heap leaching process in a bed of porous and spherical ore particles. This study is performed in two stages: first, modeling the leaching process of a soluble mineral from a spherical and porous ore particle to obtain the distribution of mineral concentrations, leaching solvent concentration and dissolved mineral in the particles (the particle model), and second, modeling the heap leaching of the mineral from a porous bed consisting of spherical and porous ore particles to obtain the distribution of mineral concentrations, leaching solvent concentration and dissolved mineral in the bed (the bed model).
Design/methodology/approach
The governing equations are derived for the particle model, and then converted into non‐dimensional form using reference quantities. The non‐dimensional equations are discretised on a uniform spherical grid fitted to the particle using finite difference method. The resulting algebraic equations are solved using Tri‐Diagonal Matrix Algorithm, and the governing equations are derived for the bed model, and then converted into non‐dimensional form using reference quantities. The non‐dimensional equations are discretised explicitly on a one‐dimensional and uniform grid fitted to the bed. The unknown quantities are evaluated using the corresponding values at the previous time interval.
Findings
The results obtained from numerical modeling show that, when the particle has a low diffusion resistance or a high chemical resistance, the reaction takes place slowly and homogeneously throughout the ore particle. On the other hand, when the bed has a low convection resistance, the reaction takes place homogeneously throughout the bed. As the convection resistance increases, the non‐homogeneous (local) behavior predominates. It is also noticed that, when the chemical reaction resistance is high, the reaction takes place homogeneously throughout the bed.
Research limitations/implications
The dynamic diffusion and movement of solution in the ore particles and ore bed are not modeled and volumetric ratio of solution in the particles and the bed and also vertical velocity of solution in the bed are assumed to be fixed constants.
Practical implications
This study shows that the reaction takes place homogeneously throughout the bed when the convection resistance is low, the diffusion resistance is high, the concentration resistance is low, and the chemical reaction resistance is high.
Originality/value
Homogeneous reaction conditions being suitable for heap leaching operations are identified. Thus, it is recommended to approach the above conditions when preparing ore heaps and designing the relevant operation.
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M. Karaminezhaad, A.H. Jafari, A. Sarrafi and Gh. Safi
To evaluate bismuth, which is inexpensive and non‐toxic, as a substitute for mercury, indium and gallium in Al‐5%Zn‐X sacrificial anode.
Abstract
Purpose
To evaluate bismuth, which is inexpensive and non‐toxic, as a substitute for mercury, indium and gallium in Al‐5%Zn‐X sacrificial anode.
Design/methodology/approach
The effect of bismuth on the electrochemical behavior of Al‐5%Zn‐Bi in the artificial sea water environment was investigated. Potentiodynamic, potentiostatic, galvanostatic, weight loss and efficiency test methods were employed. The surface of the specimens were studied by SEM and analyzed by EDAX. Image analyzer was also used.
Findings
Adding 0.3‐0.5%Bi to Al‐5%Zn alloy produces considerable active sites on the anode surface and, when the corrosion process continues, the corrosion will be uniform by joining these numerous shallow pits and a high efficiency sacrificial anode will emerge.
Research limitations/implications
Preventing segregation by good casting practice or homogenization heat treatment will be helpful to prevent unpredicted localized corrosion and investigating the effect of these processes on the performance of this new alloy is helpful. Investigating the performance of this new suggested alloy in environments like soil is highly recommended.
Practical implications
Owing to the toxicity of mercury and high price of gallium and indium, bismuth, which has a much lower price and showed a good performance in the present laboratory tests, can be a good substitute for the above mentioned elements.
Originality/value
The previous lack of a systematic research on the effect of bismuth which can be a good substitute for indium and gallium, on anodic behavior of aluminum gives this paper its high value.
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Xindang He, Run Zhou, Zheyuan Liu, Suliang Yang, Ke Chen and Lei Li
The purpose of this paper is to provide a comprehensive review of a non-contact full-field optical measurement technique known as digital image correlation (DIC).
Abstract
Purpose
The purpose of this paper is to provide a comprehensive review of a non-contact full-field optical measurement technique known as digital image correlation (DIC).
Design/methodology/approach
The approach of this review paper is to introduce the research pertaining to DIC. It comprehensively covers crucial facets including its principles, historical development, core challenges, current research status and practical applications. Additionally, it delves into unresolved issues and outlines future research objectives.
Findings
The findings of this review encompass essential aspects of DIC, including core issues like the subpixel registration algorithm, camera calibration, measurement of surface deformation in 3D complex structures and applications in ultra-high-temperature settings. Additionally, the review presents the prevailing strategies for addressing these challenges, the most recent advancements in DIC applications across quasi-static, dynamic, ultra-high-temperature, large-scale and micro-scale engineering domains, along with key directions for future research endeavors.
Originality/value
This review holds a substantial value as it furnishes a comprehensive and in-depth introduction to DIC, while also spotlighting its prospective applications.
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Masoud Mozaffari, Annunziata D’Orazio, Arash Karimipour, Ali Abdollahi and Mohammad Reza Safaei
The purpose of this paper is to improve the lattice Boltzmann method’s ability to simulate a microflow under constant heat flux.
Abstract
Purpose
The purpose of this paper is to improve the lattice Boltzmann method’s ability to simulate a microflow under constant heat flux.
Design/methodology/approach
Develop the thermal lattice Boltzmann method based on double population of hydrodynamic and thermal distribution functions.
Findings
The buoyancy forces, caused by gravity, can change the hydrodynamic properties of the flow. As a result, the gravity term was included in the Boltzmann equation as an external force, and the equations were rewritten under new conditions.
Originality/value
To the best of the authors’ knowledge, the current study is the first attempt to investigate mixed-convection heat transfer in an inclined microchannel in a slip flow regime.
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Amirreza Farahbod and Uğur Dağli
From an architectonic point of view, the identity of Iranian houses has become more enriched itself throughout history. Primarily, during the Qajardynasty (1785-1925)as a…
Abstract
From an architectonic point of view, the identity of Iranian houses has become more enriched itself throughout history. Primarily, during the Qajardynasty (1785-1925)as a consequence of the social, political, and economical changes which took place, there was a turning point from traditional architectural construction to the modernism principals of construction. In this regard, this studyaims toexplore the importance of the compatibility of the termidentity of architecture in the transformation age (a period which led tothe turning point in the history of Iranian architecture) bydescriptive (including comparative and co-relational methods) and explanative-analytical methods.
By evaluating the spatial characteristics of TraditionalIranian Houses (TIH), the study has developed a method of assessingthe architectural identity of the Qajar era. It alsointroduceda Top-down and Bottom-up processing method as the two main factors in shapingthe identityofan architectural style. By comparing both the objective and subjective indicators of shapingthe identity of TIH, the study also revealed that, in transitioning from the traditional construction to modern, the physical characteristics of the houses might change considerably, whilst lifestyles will not change at the same speed.
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Junjian Lu, Hongbin Zhong and Fei Luo
The purpose of this research is as follows: DPP-BOH-PVA has been synthesized from 1,1′:3′,1″-terphenyl-5'-boronic acid (DPP-OH) and polyvinyl alcohol (PVA). The afterglow lifetime…
Abstract
Purpose
The purpose of this research is as follows: DPP-BOH-PVA has been synthesized from 1,1′:3′,1″-terphenyl-5'-boronic acid (DPP-OH) and polyvinyl alcohol (PVA). The afterglow lifetime of DPP-BOH-PVA was studied by changing contents of DPP-OH (1, 2 and 4 Wt.%). These films were characterized with Fourier transform infrared, X-ray diffraction as structural analysis and DSC as thermal analysis. Afterglow lifetimes were evaluated as time-resolved emission decay profile analysis. Fiber films of DPP-BOH-PVA-2-E have been prepared by electrospinning method with the diameter of 5 μm and afterglow life time of 2.1 s (@ 535 nm) under ambient conditions. Stimulus responsive properties with afterglow emission for fiber film were investigated.
Design/methodology/approach
During the synthesis of the polymer, modification was carried out using DPP-OH/PVA with a molar ratio of 1/4, under an alkalinity medium with ammonium hydroxide and with a temperature of 80°C.
Findings
XRD results indicate that DPP-BOH-PVA film had high crystallinity, which is crucial for preparing organic room temperature phosphorescence (RTP) materials.
Research limitations/implications
The reaction mixture must be stirred continuously. Temperature should be controlled to prevent the rapid evaporation of ammonium hydroxide.
Practical implications
This study provides technical information for the synthesis of multidimensional stimulation response RTP micron fiber thin film. The electrospinning technology may also promote the applications of the large areas of RTP films.
Social implications
This resin will be used for the multidimensional stimulation response RTP fiber thin film.
Originality/value
The diameter of fiber film of PP-BOH-PVA-2-E by electrospinning method was in the range of 5 μm, and its afterglow lifetime decayed to be 2.1 s.
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Srinivas Naik Lonavath and Hadya Boda
This Friction stir welding study aims to weld thick AA8011 aluminium plates, and the interface joints created with a variety of tool pin profiles were examined for their effects…
Abstract
Purpose
This Friction stir welding study aims to weld thick AA8011 aluminium plates, and the interface joints created with a variety of tool pin profiles were examined for their effects on the welding process.
Design/methodology/approach
Scanning electron microscopy and optical microscopy and X-ray diffraction were used to examine the macro and micro-structural characteristics, as well as the fracture surfaces, of tensile specimens. The mechanical properties (tensile, hardness tests) of the base metal and the welded specimens under a variety of situations being tested. Additionally, a fracture toughness test was used to analyse the resilience of the base metal and the best weldments to crack formation. Using a response surface methodology with a Box–Behnken design, the optimum values for the three key parameters (rotational speed, welding speed and tool pin profile) positively affecting the weld quality were established.
Findings
The results demonstrate that a defect-free junction can be obtained by using a cylindrical tool pin profile, increasing the rotational speed while decreasing the welding speeds. The high temperature and compressive residual stress generated during welding leads to the increase in grain size. The grain size of the welded zone for optimal conditions is significantly smaller and the hardness of the stir zone is higher than the other experimental run parameters.
Originality/value
The work focuses on the careful examination of microstructures behaviour under various tool pin profile responsible for the change in mechanical properties. The mathematical model generated using Taguchi approach and parameters was optimized by using multi-objectives response surface methodology techniques.
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This paper aims to present an adaptation of digital image correlation (DIC) to the electronics industry for reliability assessment of electronic packages. Two case studies are…
Abstract
Purpose
This paper aims to present an adaptation of digital image correlation (DIC) to the electronics industry for reliability assessment of electronic packages. Two case studies are presented: one for warpage measurement of a micro-electro-mechanical system (MEMS) package under different temperature conditions and the other for the measurement of transient displacements on the surface of a printed circuit board (PCB) assembly under free-fall drop conditions, which is for explaining the typical camera setup requirement and comparing among different boundary conditions by fastening methods of PCB.
Design/methodology/approach
DIC warpage measurements on a small device, such as a MEMS package, require a special speckle pattern. A new method for the creation of speckle patterns was developed using carbon coating and aluminum evaporative deposition. To measure the transient response on the surface of a PCB during a free-fall impact event, three-dimensional (3D) DIC was integrated with synchronized stereo-high speed cameras. This approach enables the measurement of full-field displacement on the PCB surface during a free-fall impact event, contrary to the localized information that is obtained by the conventional strain gage and accelerometer method.
Findings
The authors suggest the proposed patterning method to the small-sized microelectronics packages for DIC measurements. More generally, the idea is to have a thin layer of the dark or bright color of the background and then apply the white or black colored pattern, respectively, so that the surface has high contrast. Also, to achieve a proper size of speckles, this paper does not want to expose the measuring objects to high temperatures or pressures during the sample preparation stage. Of course, it seems a complicated process to use aluminum evaporator, carbon coater and electroformed mesh. However, the authors intend to share one of the solutions to achieve a proper pattern on such small-sized electronic packages.
Originality/value
3D DIC technique can be successfully implemented for the measurement of micro-scale deformations in small packages (such as MEMS) and for the analysis of dynamic deformation of complex PCB.
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A.R. Mirhabibi, F. Moztarzadeh, A. Aghajani Bazazi, M. Solati, A. Maghsoudipour and M.H. Sarrafi
Long afterglow Sr2MgSi2O7 (SMS) phosphor was prepared by Douby's methods at high temperature and reductive atmosphere. The excitation and emission spectra of this phosphor showed…
Abstract
Long afterglow Sr2MgSi2O7 (SMS) phosphor was prepared by Douby's methods at high temperature and reductive atmosphere. The excitation and emission spectra of this phosphor showed that both had broad bands and that the main emission peak at 469 nm was due to 4f‐5d transitions of Eu+2 and implied that the luminescence centres Eu+2 occupied the Sr+2 sites in the Sr2MgSi2O7 host. The phosphor doped only with Eu ions did not demonstrate the long afterglow phenomenon, but when co‐doped with Dy+3 ions in the SMS matrix, significant long afterglow was observed.
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Amir Maghsoudipour, Mohamad Hassan Sarrafi, Fathollah Moztarzadeh and Ali Aghajani Bazazi
The purpose of this paper is to investigate the effect of boric acid as a flux on the formation of the akermanite phase and optical properties of SrMgSi2O7:Eu,Dy phosphors.
Abstract
Purpose
The purpose of this paper is to investigate the effect of boric acid as a flux on the formation of the akermanite phase and optical properties of SrMgSi2O7:Eu,Dy phosphors.
Design/methodology/approach
The silicate‐based phosphor is prepared by sol‐gel method. Sr(NO3)2, Mg(NO3)2 · 6H2O, Dy2O3, Eu2O3, are added to distilled water in their stoichiometric ratio, the obtained solution are mixed with H3BO3 (in the range of 0.01‐0.5 mol%) and a polymeric compound TESO (C8H2O4Si). At the end, the phase composition and optical properties are investigated using X‐ray diffraction (XRD) and spectrophotometer analysis, respectively.
Findings
The XRD results showed that the akermanite (Sr2MgSi2O7) is the only crystalline phase which is detected in the sample containing 0.05 mol% boric acid. Increasing of boric acid does not have a great effect on the XRD patterns intensity. Spectrophotometer analysis results show three maximum at 365, 395 and 430 nm on the excitation spectra. It also shows intensity of the excitation and emission spectra increased by adding boric acid up to 0.25 mol% and a sudden drop at 0.5 mol% boric acid.
Originality/value
Using boric acid as a flux, enhances formation of akermanite phase at lower temperature with desirable optical properties and a cost‐benefit way for industrial production. In this research, optimum value of boric acid was determined using XRD data, emission and excitation spectra.