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    Age-hardening behavior and phase identification in solution-treated AEREX 350 superalloy

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 37, Issue 7 , 2006 , Pages 2051-2057 ; 10735623 (ISSN) Asgari, S ; Sharif University of Technology
    2006
    Abstract
    This article presents results of an investigation on age-hardening behavior of superalloy AEREX 350. Microhardness testing was employed to evaluate the age-hardening response of the alloy while optical, scanning, and transmission electron microscopy techniques were used to characterize the major phases formed during the aging process. No significant hardening was found in solution-treated samples aged at temperatures up to about 680 °C. Aging at 700 °C up to 950 °C, however, caused a characteristic hardening response. This hardening was concurrent with the formation of γ', an ordered phase with L12 structure, as fine precipitate distributed throughout the fcc matrix. In the temperature range... 

    A simultaneous method for phase identification and equilibrium calculations in reactive mixtures

    , Article Chemical Engineering Research and Design ; Volume 89, Issue 10 , 2011 , Pages 1901-1908 ; 02638762 (ISSN) Avami, A ; Saboohi, Y ; Sharif University of Technology
    Abstract
    Phase identification is an important aspect of flash calculations which can affect the phase and chemical equilibria. A new simultaneous approach for reactive mixtures, based on τ-method which relies on modification equation for mole fraction summation, is introduced in this paper. In the proposed methodology, phase identification and solution of governing equations can be performed simultaneously and effectively. In addition, prior knowledge of the number of phases in advance is not required. Present methodology has been verified with the help of case studies and results are discussed in the present paper. The results indicate that the present method gives us information about presence of... 

    Phase identification of singlephase customers and PV panels via smart Meter data

    , Article IEEE Transactions on Smart Grid ; Volume 12, Issue 5 , 2021 , Pages 4543-4552 ; 19493053 (ISSN) Heidari-Akhijahani, A ; Safdarian, A ; Aminifar, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    With proliferation of single-phase rooftop photovoltaic (PV) panels, phase balancing in low voltage (LV) distribution feeders becomes the point of concern. In this way, identification of the hosting phase of connected single-phase customers and PV panels is a prerequisite. This paper proposes an optimization model for the phase identification problem. The objective is to minimize the summation of the absolute error between estimated and measured variables. Smart meters (SMs) data including active and reactive power absorptions/injections, nodal voltage magnitudes, and network configuration data form the input of the model. Potential errors in the input data are captured in the model while... 

    A MILP model for phase identification in LV distribution feeders using smart meters data

    , Article 2019 Smart Gird Conference, SGC 2019, 18 December 2019 through 19 December 2019 ; 2019 ; 9781728158945 (ISBN) Akhijahani, A. H ; Hojjatinejad, S ; Safdarian, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Nowadays, with the increasing use of renewable energies in low voltage (LV) feeders, phase balancing research areas are of great importance. However, the lack of information about the hosting phase of customers and renewable sources is the missing link in such researches. To address this barrier, this paper proposes a mixed integer linear programming (MILP) method to identify the hosting phase of customers as well as renewable energies, such as photovoltaic (PV) panels. The model considers potential error in the input data. To overcome the complexity caused by data error, the input data in several time intervals are taken into account by the model. The model solves the phase identification... 

    Synthesis of Fe-Ni nano-particles by low-temperature hydrogen reduction of mechanically alloyed Ni-ferrite

    , Article Journal of Alloys and Compounds ; Volume 485, Issue 1-2 , 2009 , Pages 484-487 ; 09258388 (ISSN) Azizi, A ; Sadrnezhaad, Kh ; Sharif University of Technology
    2009
    Abstract
    Fe-Ni nano-particles were synthesized by mechanical alloying and subsequent low-temperature hydrogen reduction of oxide mixtures. First, single-phase nickel ferrite was mechanically synthesized for 30 h with steel balls to powder weight ratio of 20 while the milling was operated at 300 rpm. The as-milled powder was then placed in contact with hydrogen at 600 °C for 1 h. Reduction reactions resulted in production of Fe-Ni nano-particles. Phase identification, morphological and microstructural studies, chemical analysis and magnetic property determination were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), energy dispersive... 

    Phase formation and change of magnetic properties in mechanical alloyed Ni0.5Co0.5Fe2O4 by annealing

    , Article Journal of Magnetism and Magnetic Materials ; Volume 322, Issue 1 , 2010 , Pages 56-59 ; 03048853 (ISSN) Azizi, A ; Yoozbashizadeh, H ; Yourdkhani, A ; Mohammadi, M ; Sharif University of Technology
    Abstract
    The effects of milling time and annealing temperature on phase formation, microstructure and magnetic properties of nickel-cobalt ferrite synthesized from oxide precursors by mechanical alloying were studied. The study of milling time effects on phase formation of milled materials showed that if milling continues up to 55 h, single phase nano-sized nickel-cobalt ferrite is obtained. Also, magnetic properties of powders versus milling time and annealing at different temperatures extensively changed, so that annealing at 1200 °C increased the magnetization saturation of the as-milled powder from 15.1 to 53.6 emu/g. X-ray powder diffraction technique (XRD) with Cu-Ka radiation was employed for...