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51.
Jian Zhou Nasim Aghili Ebrahim Noroozi Ghaleini Dieu Tien Bui M. M. Tahir Mohammadreza Koopialipoor 《Engineering with Computers》2020,36(2):713-723
One of the undesirable phenomena in the surface mines, which results in various hazards for human and facilities, is flyrock. It seems that the careful study of the subject and its effects on the environment can affect the control of flyrock hazards in the studied area. Therefore, the use of intelligent models and methods which are capable of predicting and simulating the risk of flyrock can be considered as an appropriate solution in this regard. The current research was conducted using nonlinear models and Monte Carlo (MC) simulation. The data used in this study consist of 260 samples of rock thrown from a mine in Malaysia. The parameters used in these models include hole’s diameter (D), hole’s depth (HD), burden to spacing (BS), stemming (ST), maximum charge per delay (MC), and powder factor (PF). At first, multiple regression analysis (MRA) and artificial neural network (ANN) models were used in order to develop a non-linear relationship between dependent and independent parameters. The ANN model was an appropriate predictor of flyrock in the mine. Then using the best implemented model of ANN, the flyrock environmental phenomenon was simulated using MC technique. MC simulation showed a proper level of accuracy of flyrock ranges in the mine. Using this simulation, it can be concluded with 90% accuracy that the Flyrock phenomenon does not exceed 331 m. Under these conditions, this simulation can be used for various areas requiring risk assessment. Finally, a sensitive analysis was carried out on data. This analysis showed MC has the greatest effect on flyrock. 相似文献
52.
Koopialipoor Mohammadreza Fahimifar Ahmad Ghaleini Ebrahim Noroozi Momenzadeh Mohammadreza Armaghani Danial Jahed 《Engineering with Computers》2020,36(1):345-357
Engineering with Computers - Prediction of tunnel boring machine (TBM) performance parameters can be caused to reduce the risks associated with tunneling projects. This study is aimed to introduce... 相似文献
53.
Hosein Morshedi Mosayeb Naseri Mohammad Reza Hantehzadeh Seyed Mohammad Elahi 《Journal of Electronic Materials》2018,47(4):2290-2297
In this paper, using a first principles calculation, a two-dimensional structure of silicon-antimony named penta-Sb\(_{2}\)Si is predicted. The structural, kinetic, and thermal stabilities of the predicted monolayer are confirmed by the cohesive energy calculation, phonon dispersion analysis, and first principles molecular dynamic simulation, respectively. The electronic properties investigation shows that the pentagonal Sb\(_{2}\)Si monolayer is a semiconductor with an indirect band gap of about 1.53 eV (2.1 eV) from GGA-PBE (PBE0 hybrid functional) calculations which can be effectively engineered by employing external biaxial compressive and tensile strain. Furthermore, the optical characteristics calculation indicates that the predicted monolayer has considerable optical absorption and reflectivity in the ultraviolet region. The results suggest that a Sb\(_{2}\)Si monolayer has very good potential applications in new nano-optoelectronic devices. 相似文献
54.
Morphology enhancement of TiO2/PVP composite nanofibers based on solution viscosity and processing parameters of electrospinning method
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Soraya Mirmohammad Sadeghi Mohammadreza Vaezi Asghar Kazemzadeh Roghayeh Jamjah 《应用聚合物科学杂志》2018,135(23)
In this work, different sol solutions with various titanium tetraisopropoxide (TIP)/glacial acetic acid ratios in 2‐propanol with 5 wt % poly(vinyl pyrrolidone) (PVP) (Mw = 360,000 g/mol) were prepared and electrospun. Composition of the prepared sols and as‐spun TiO2/PVP nanofibers were determined by Fourier transform infrared and Raman spectroscopy methods. Morphology of the electrospun TiO2/PVP nanofibers was studied by scanning electron microscopy and transmission electron microscopy (TEM) techniques. Rheometry measurements of the sol solutions showed decrease of viscosity upon the addition of TIP to the polymer solutions with constant polymer and acid concentrations. The sol solution having the lowest viscosity (at shear rate 10 s?1) but the highest TIP/glacial acetic acid ratio showed beaded nanofibers morphology when electrospun under 10 and 12 kV applied voltage while injection rate, needle tip to collector distance, and needle gauge were kept constant. However, smooth electrospun TiO2/PVP composite nanofibers with the average nanofibers diameters (148 ± 79 nm) were achieved under the same condition when applied voltage increased to 15 kV. TEM micrographs of the electrospun TiO2/PVP nanofiber showed that the TiO2 particles with continuous structure are formed at the middle of the nanofiber and distributed along its axis. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46337. 相似文献
55.
High‐performance carboxylate superplasticizers for concretes: Interplay between the polymerization temperature and properties
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Alireza Tajbakhshian Mohammad Reza Saeb Seyed Hassan Jafari Farhood Najafi Hossein Ali Khonakdar Mohammadreza Ayoubi Farzaneh Hassanpour Asl 《应用聚合物科学杂志》2017,134(23)
Polycarboxylate superplasticizers based on acrylic acid (AA) and maleic anhydride (MAn) were synthesized via free‐radical copolymerization with an ethylene glycol monomer and characterized. The copolymerization temperature (ranging from 50 to 90 °C) appeared to be the key operating factor governing the chemical structure of the superplasticizers. The chemical structures of the products were analyzed by gel permeation chromatography, whereas an optimized sample was further analyzed by Fourier transform infrared spectroscopy and 1H‐NMR. Superplasticizers of the AA and MAn classes were then incorporated into concrete, and their performances were measured by slump and slump loss tests, where a large dependency of the microstructure on the synthesis temperature was recognized. The optimum temperatures were found to be 50 and 80 °C for the AA and MAn modifiers, respectively. At their own optimum temperatures, the AA and MAn superplasticizer revealed slump losses from 23 to 4 cm and 15 to 5 cm, respectively, after 45 min. The chemical structures of the plasticizers were patterned illustratively to speculate the performance of each superplasticizer according to changes that took place in the backbone length and side‐chain density. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44908. 相似文献
56.
Investigation of the effect of magnetic field on mass transfer parameters of CO2 absorption using Fe3O4‐water nanofluid
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Mohammad Hossein Karimi Darvanjooghi Maedeh Pahlevaninezhad Ali Abdollahi Seyyed Mohammadreza Davoodi 《American Institute of Chemical Engineers》2017,63(6):2176-2186
In this study, the enhancement of physical absorption of carbon dioxide by Fe3O4‐water nanofluid under the influence of AC and DC magnetic fields was investigated. Furthermore, a gas‐liquid mass transfer model for single bubble systems was applied to predict mass transfer parameters. The coated Fe3O4 nanoparticles were prepared using co‐percipitation method. The results from characterization indicated that the nanoparticles surfaces were covered with hydroxyl groups and nanoparticles diameter were 10–13 nm. The findings showed that the mass transfer rate and solubility of carbon dioxide in magnetic nanofluid increased with an increase in the magnetic field strength. Results indicated that the enhancement of carbon dioxide solubility and average molar flux gas into liquid phase, particularly in the case of AC magnetic field. Moreover, results demonstrated that mass diffusivity of CO2 in nanofluid and renewal surface factor increased when the intensity of the field increased and consequently diffusion layer thickness decreased. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2176–2186, 2017 相似文献
57.
Mohammadreza Khorshidi Gholamreza Dadashzadeh 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(5):609-629
Low terahertz (THz) radiation power and low efficiency are the well-known drawbacks of photoconductive antennas (PCAs). To increase THz-radiation power of PCAs, a dielectric structure with periodic low-temperature-grown GaAs strips is proposed. Transmitted power of the proposed structure is obtained from a theoretical model, and further confirmed by finite element simulations. Results show that the structure is capable to transmit into the substrate 90 % of the power of transverse magnetic wave with wavelength as wide as from 0.7 to 1.0 μm. Favorability of this property gets amplified when power transmission in a wide range of frequency bandwidth is desired, e.g., for optical pulse with short duration time incident to PCA, which generates carriers in the semiconductor that create THz emission. Furthermore, the proposed dielectric structure with periodic strips, the whole structure placed in between electrodes of PCA is considered, and analyzed by the existing photoconductive antenna equivalent circuit model, to see how power radiation changes. Interestingly, THz-radiation power enhancements of 70 and 20 % are evinced for, respectively, 20 and 150 mW incident optical powers as instances, as compared to PCA without strips in the gap area. 相似文献
58.
Maryam Basij Mohammadreza Yazdchi Arash Taki Payman Moallem 《Signal, Image and Video Processing》2017,11(6):1009-1016
Intravascular ultrasound (IVUS) is clinically available for visualizing coronary arteries. However, it suffers from acoustic shadow areas and ring-down artifacts as two of the common issues in IVUS images. This paper introduces an approach which can overcome these limitations. As shadow areas were displayed behind hard plaques in the IVUS grayscale images, calcified plaques were first segmented by using Otsu threshold. Then, active contour, histogram matching, and local histogram matching are implemented. In addition, a new modified circle Hough transform is introduced to remove the ring-down artifacts from IVUS images. In order to evaluate the efficacy of this new method in detection of shadow and ring-down regions, 300 IVUS images are considered. Sensitivity of 89% and specificity of 92% are achieved from a comparison in revelation of calcium along with shadow in the proposed method and virtual histology images. Also, area differences of \(5.83 \pm 3.3\) and \(5.65 \pm 2.83\) are obtained, respectively, for ring-down and shadow domain when compared to measures performed manually by a clinical expert. 相似文献
59.
Piao Y Kim J Na HB Kim D Baek JS Ko MK Lee JH Shokouhimehr M Hyeon T 《Nature materials》2008,7(3):242-247
The thermal treatment of nanostructured materials to improve their properties generally results in undesirable aggregation and sintering. Here, we report on a novel wrap-bake-peel process, which involves silica coating, heat treatment and finally the removal of the silica layer, to transform the phases and structures of nanostructured materials while preserving their nanostructural characteristics. We demonstrate, as a proof-of-concept, the fabrication of water-dispersible and biocompatible hollow iron oxide nanocapsules by applying this wrap-bake-peel process to spindle-shaped akagenite (beta-FeOOH) nanoparticles. Depending on the heat treatment conditions, hollow nanocapsules of either haematite or magnetite were produced. The synthesized water-dispersible magnetite nanocapsules were successfully used not only as a drug-delivery vehicle, but also as a T2 magnetic resonance imaging contrast agent. The current process is generally applicable, and was used to transform heterostructured FePt nanoparticles to high-temperature face-centred-tetragonal-phase FePt alloy nanocrystals. 相似文献
60.
A. Andres Leal Mohammadreza Naeimirad Laura Gottardo Philipp Schuetz Ali Zadhoush Rudolf Hufenus 《国际聚合物材料杂志》2016,65(9):451-456
The development of thermoplastic fibers containing a liquid core is described. Internal morphology analysis confirms that the liquid-containing core is composed of a continuous cylindrical microchannel of constant diameter. Microfluidic experiments on both liquid core and reference hollow fibers were conducted by pumping distilled water through several filaments simultaneously. The observed fluid motions are satisfactorily described by the Hagen-Poiseuille law, indicating that the hollow and liquid core fibers have internal diameters of 31.6 and 14.8 µm, respectively. Flushing the liquid core fibers with a surfactant solution efficiently removes the saturated ester initially used during the melt spinning of the fiber. 相似文献