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Wyszukujesz frazę "Ahmadi, R." wg kryterium: Autor

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    Wyświetlanie 1-8 z 8
    Tytuł:
    Raman Spectra and Structural Data of the Nanocrystalline KTP $(KTiOPO_4)$ Synthesized by Pechini Method
    Autorzy:
    Malekfar, R.
    Cheraghi, A.
    Ahmadi, G.
    Khanzadeh, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1585099.pdf
    Data publikacji:
    2009-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.30.-j
    77.84.Fa
    Opis:
    Nanocrystalline KTP powders are synthesized using a modified Pechini method. The structural and lattice modes of the products are investigated via X-ray diffraction, micro Raman backscattering spectroscopy, UV/vis/NIR and FT-IR transmission spectroscopy. The Debye-Scherrer formula is used to confirm the grain sizes estimated by the scanning electron microscopy slides.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 6; 1073-1075
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physical properties of psyllium seed
    Autorzy:
    Ahmadi, R.
    Kalbasi-Ashtari, A.
    Gharibzahedi, S.M.T.
    Powiązania:
    https://bibliotekanauki.pl/articles/24892.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    physical property
    psyllium
    seed
    postharvest technology
    Plantago ovata
    India
    plant cultivation
    Opis:
    Physical properties ie dimensions, volume, surface area, sphericity, true density, porosity, angle of repose, terminal velocity, static and dynamic friction coefficients on plywood, stainless steel, glass and galvanized iron sheet, force required for initiating seed rupture in horizontal and vertical orientations of psylliumseed at amoisture content of 7.2%(w.b.)were determined.
    Źródło:
    International Agrophysics; 2012, 26, 1
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improvement of chalcopyrite atmospheric leaching using controlled slurry potential and additive treatments
    Autorzy:
    Jafari, M.
    Karimi, G.
    Ahmadi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/110092.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    chalcopyrite
    improved leaching
    controlled oxidation-reduction potential
    additive treatment
    pyrite
    sodium chloride
    silica
    Opis:
    In this study, the synergistic effects of the oxidation-reduction potential (ORP) of leaching slurry and additives (pyrite, sodium chloride and silica) on chalcopyrite atmospheric leaching were investigated. According to the best results of leaching experiments, in the optimum ORP range of 410-430 mV, galvanic (pyrite mass ratio of 4:1), chemical (1.5 mol/dm3 sodium chloride concentration), galvanochemical (pyrite mass ratio of 4:1 and 1.5 mol/dm3 sodium chloride concentration) and mechanical (30 g/dm3 silica concentration) treatments provided 29.8, 46.4, 48.6 and 6.7% increase in the copper recovery, respectively. In galvanic treatments, effective surface corrosion of chalcopyrite was the reason for enhanced chalcopyrite dissolution. In chemical and galvanochemical treatments, considerable surface porosity of chalcopyrite was responsible for accelerated leaching. Also, in mechanical treatments, removing the remained passive layer from the chalcopyrite surface improved leaching. SEM results showed extensive porosity in the chalcopyrite surface in the presence of pyrite and sodium chloride and even more porosity in the presence of their combination. SEM results also showed obviously clean surface of chalcopyrite in the presence of silica. The comparison of ORP-assisted and non-ORP-assisted experiments showed that there were 8, 5.2, 3.9 and 0.5% more copper recoveries in galvanic, chemical, galvanochemical and mechanical treatments with ORP assistance, respectively. The reason was the fewer chalcopyrite surface passivation, which caused the additives to perform better.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1228-1240
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Earthquake analysis of arch dams including the effects of foundation discontinuities and proper boundary conditions
    Autorzy:
    Ferdousi, A.
    Mostafa Gharabaghi, A. R.
    Ahmadi, M. T.
    Chenaghlou, M. R.
    Emami Tabrizi, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/279306.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    concrete arch dam
    non-homogeneous and discontinuous rock foundation
    nonlinear dynamic analysis
    boundary conditions
    Opis:
    The interaction between dam foundation and rocks plays a significant role in the design and analysis of concrete arch dams. In the current study, comprehensive dynamic analysis of the dam-reservoir-foundation system is performed by developing a non-linear finite element program. The objective of this paper is to study the seismic behavior of a concrete arch dam taking into account the effects of foundation discontinuities and foundation inhomogeneity on the stability. Proper modeling truncated boundary conditions at the far-end of the foundation and reservoir fluid domain as well as to correctly apply the in-situ stresses for the foundation rock represents field conditions in the model more realistically. In this paper, the nonlinear seismic response of the dam-reservoir-foundation system includes dam-canyon interaction, dam body contraction joint opening, discontinuities (possible sliding planes) of the foundation rock and the failure of the joined rock and concrete materials. The results for the Karun 4 dam as a case study revealed the substantial effect of modeling discontinuities and boundary conditions of the rock foundation under seismic excitation that needs to be considered in the design of new dams and can be applied to seismic safety evaluation of the existing dams.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2014, 52, 3; 579-594
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of bubble size distribution in a laboratory mechanical flotation cell by a laser diffraction technique
    Autorzy:
    Mazahernasab, R.
    Ahmadi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/110401.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    bubble size distribution
    mechanical flotation cell
    laser diffraction technique (LDT)
    Image Analysis Technique (IAT)
    effective parameters
    Opis:
    In this study, a laser diffraction technique (LDT) was used to measure size distribution of bubbles generated in a two-phase system in a laboratory mechanical flotation cell. In LDT, a laser light beam passed through the bubbles inside the measurement cell and the scattered light was recorded by detectors. In order to show the effectiveness of LDT, an image analysis technique (IAT) was applied in parallel to measure the size of bubbles. To determine the bubble size by IAT, around 200 images were taken in each test. In addition, the important operating parameters of the mechanical flotation cell affecting the bubble size distribution, including the impeller speed, aeration rate and frother concentration, were investigated. The response parameter in this study was Db(50) which represent the size of bubble at which there is 50% of the distribution. The results of this study showed that the LDT and IAT techniques were in a good agreement when Db(50) was in the range of -800+400 μm and there was a discrepancy for Db(50) in the range of -400+100 μm. Furthermore, Db(50) decreased from 727 to 284 μm when impeller speed increased from 700 to 1200 rpm. Additionally, an increase in the aeration rate from 1 dm3/min to 2.5 dm3/min led to a rise in Db(50) from 418 to 456 μm. Finally, increasing the frother concentration from 10 to 60 ppm reduced the Db(50) from 704 to 387 μm.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2016, 52, 2; 690-702
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cutoff grade optimization based on maximizing net present value using a computer model
    Autorzy:
    Ahmadi, M. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/91898.pdf
    Data publikacji:
    2018
    Wydawca:
    Główny Instytut Górnictwa
    Tematy:
    cut-off grade optimization
    maximization of net present value
    Lane's theory
    computer model
    optymalizacja doboru granicy opłacalności
    maksymalizacja wartości bieżącej netto
    teoria Lane’a
    model komputerowy
    Opis:
    After designing the final range of open pit mines, one of the first essential decisions to be made in the production planning framework is to determine the cutoff grade. The cutoff grade of mines, due to interconnections with technical and economic parameters, is one of the most important parameters for the design of open pit mines. Considering the fundamental role of plant cutoff grade on the economical operation of a mine, the optimal selection of this grade is of great importance. One of the main problems in mining operations is how to determine the optimal cutoff grades of ore deposits at different periods during the life of a mine, it can be considered based on one of the goals of maximizing annual profit or net present value extraction during the mining period. Despite the existence of a range of different techniques for determining the optimal cutoff grade, Lane's algorithm is usually the most widely used cutoff grade optimization technique, which is calculated taking into account the technical and economic factors of production. Cutoff grade optimization with the goal of maximizing the net present value over the years of the mine's life, as well as the correlation with the distribution of the grade and tonnage of the remaining ore, requires a long calculation process, especially for large mines. In this research, optimal cutoff grade programming based on Lane's theory and aimed at maximizing the net present value in MATLAB software (computer model) has been carried out. Mineral operations consist of three phases: mining, processing, and refining. In single-product and single-process mode, the optimum cut-off grade and the net present value of production are calculated for each year of the mine's life. After validating the outputs of the model, the implementation of the computer model based on the data of Gol Gohar iron mine No.1 in a five-year plan was carried out. The changes in optimal cutoff grade and changes in net present value from 48.65% to 18,582 billion rials in the early years of the mine increased to 40.5% and approximately 3000 billion rials at the end of the mine's life.
    Źródło:
    Journal of Sustainable Mining; 2018, 17, 2; 68-75
    2300-1364
    2300-3960
    Pojawia się w:
    Journal of Sustainable Mining
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Buckling of imperfect thick cylindrical shells and curved panels with different boundary conditions under external pressure
    Autorzy:
    Alashti, R. A.
    Ahmadi, S. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/281593.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    initial imperfection
    buckling load
    thick cylindrical panel
    Opis:
    In this paper, the effects of initial imperfections on the buckling behavior of thick cylindrical shells and curved panels are investigated. It is assumed that the shell has an axisymmetric and periodic initial imperfection in the axial direction. The shell is assumed to have different boundary conditions and subjected to pure external pressure loading. Governing differential equations are developed on the basis of the second Piola-Kirchhoff stress tensor and are re- duced to a homogenous linear system of equations using the differential quadrature method. The effects of different boundary conditions, geometric ratios, curvature and imperfection parameter on the buckling behavior of isotropic thick cylindrical shells and curved panels are carefully discussed. The results obtained by the present method are verified with finite element solutions and those reported in the literature.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2014, 52, 1; 25-36
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption of Cr(VI) by Natural Clinoptilolite Zeolite from Aqueous Solutions: Isotherms and Kinetics
    Autorzy:
    Jorfi, S.
    Ahmadi, M. J.
    Pourfadakari, S.
    Jaafarzadeh, N.
    Soltani, R. D. C.
    Akbari, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/778561.pdf
    Data publikacji:
    2017
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    Adsorption
    Clinoptilolite Zeolite
    Cr(VI)
    Isotherm
    Reaction Kinetics
    Opis:
    The main aim of this study was to evaluate the efficiency of natural zeolite for Cr(VI) removal from aqueous solutions. Following simple modification of adsorbent, the effect of operational parameters including pH (2–10), adsorbent dosage (2–20 g/L), contact time (5–150 min) and Cr(VI) concentration (10–50 mg/L) were studied according to one-factor-at-a-time procedure. The maximum Cr(VI) removal of 99.53% was obtained at initial pH of 2, contact time of 30 min, adsorbent dosage of 8 g/L and initial chromium concentration of 10 mg/L. The Freundlich isotherm was best fitted with experimental data (R2 = 0.951). Also, type 1pseudo second order kinetic model showed the most correlation (R2 = 1) with the experimental data. According to obtained results, it can be concluded that the application of clay-like adsorbents such as natural clinoptilolite zeolite can be considered as an efficient alternative for final treatment of effluents containing Cr(VI).
    Źródło:
    Polish Journal of Chemical Technology; 2017, 19, 3; 106-114
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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