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A new approach for ranking fuzzy numbers based on α-cuts
Hadi Basirzadeh,Roohollah Abbasi 한국전산응용수학회 2008 Journal of applied mathematics & informatics Vol.26 No.3-4
Comparison between two or more fuzzy numbers, along with their ranking, is an important subject discussed in scholarly articles. We endeavor in this paper to present a simple yet effective parametric method for comparing fuzzy numbers. This method offer significant advantages over similar methods, in comparing intersected fuzzy numbers, rendering the comparison between fuzzy numbers possible in different decision levels. In the process, each fuzzy number will be given a parametric value in terms of α, which is dependent on the related α−cuts. We have compared this method to Cheng’s centroid point method [5] (The relation of calculating centroid point of a fuzzy number was corrected later on by Wang [12]). The proposed method can be utilized for all types of fuzzy numbers whether normal, abnormal or negative. Comparison between two or more fuzzy numbers, along with their ranking, is an important subject discussed in scholarly articles. We endeavor in this paper to present a simple yet effective parametric method for comparing fuzzy numbers. This method offer significant advantages over similar methods, in comparing intersected fuzzy numbers, rendering the comparison between fuzzy numbers possible in different decision levels. In the process, each fuzzy number will be given a parametric value in terms of α, which is dependent on the related α−cuts. We have compared this method to Cheng’s centroid point method [5] (The relation of calculating centroid point of a fuzzy number was corrected later on by Wang [12]). The proposed method can be utilized for all types of fuzzy numbers whether normal, abnormal or negative.
Prediction of fatigue life in cold expanded Al-alloy 2024-T3 plates used in double shear lap joints
Hadi Taghizadeh,Tajbakhsh Navid Chakherlou,Afshin Babaei Aghdam 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5
To predict fatigue crack initiation and fatigue crack growth lives in cold expanded double shear lap joints a numerical method has been employed. The total estimated fatigue lives were compared with available experimental fatigue test results for plain hole and cold expanded hole specimens of Al 2024-T3 in double shear lap joints. Three-dimensional finite element simulations have been performed in order to obtain the created residual stresses field due to cold expansion and subsequent far field longitudinal loading in the double shear lap joint. The obtained stress and strain distributions from the finite element analyses were employed to predict stress concentration factors to calculate fatigue crack initiation and fatigue crack growth lives using AFGROW computer code. The predicted fatigue lives demonstrate that there is a good agreement between the proposed method and experimental fatigue test results.
Hadi Baseri,Mohammad Nader Lotfollahi,Ali Haghighi Asl 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.1
An equation of state (EOS), which is based upon contributions to the Helmholtz energy, is presented for systems containing aqueous electrolyte solutions at high pressure. The Peng-Robinson equation of state is used to provide the Helmholtz energy of a reference system. The electrolyte terms consist three terms containing a modified Debye- Hückel term for long-range electrostatic interactions, the Born energy contribution for electrostatic works and a Margules term for short-range electrostatic interactions between ions and solvents. The binary and ternary interaction parameters of the equation of state are obtained by experimental osmotic coefficient data. Systems that were studied here are (water+ NaCl+SC-CO2), (water+NH4Cl+SC-CO2), (water+Na2SO4+SC-CO2) and (water+methanol+NaCl+SC-CO2). It is found that the proposed equation of state is able to accurately represent the experimental data over a wide range of pressure, temperature and salt concentration.
Experimental crack analyses of concrete-like CSCBD specimens using a higher order DDM
Hadi Haeri 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.16 No.6
A simultaneous analytical, experimental and numerical analysis of crack initiation, propagation and breaking process of the Central Straight through Crack Brazilian Disk (CSCBD) specimens under diametrical compression is carried out. Brazilian disc tests are being accomplished to evaluate the fracturing process based on stress intensity factors (SIFs). The effects of crack inclination angle and crack length on the fracturing processes have been investigated. The same experimental specimens have been numerically modeled by a higher order indirect boundary element method (HDDM). These numerical results are compared with the existing experimental results proving the accuracy and validity of the proposed numerical method.
Hadi Share Mohammadi,Ali Haghighi Asl,Maryam Khajenoori 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.11
To improve the bioavailability of ampicillin trihydrate (AMP) as a poorly water-soluble drug, the nanonization of AMP particles was carried out by solvent anti-solvent precipitation for the first time. In this method the subcritical water (SW) and cold water at ambient conditions were utilized as the solvent and anti-solvent, respectively. At first, the solubility of AMP in SW was measured. The solubility of AMP in SW at a constant pressure of 5MPa and the temperature range from 303.15 to 403.15 K was found to range from 0.380×103 to 17.689×103 mole fractions. The effects of three independent variables, including SW temperature, polyethylene glycol concentration, and anti-solvent temperature, on the particle size and morphology of the precipitated nanoparticles were studied. The obtained results of analyses confirmed that the AMP particles were nanosized to the smallest mean size of 66.5 nm using an environmentally friendly method without the requirement of organic solvents and related post-processing purification stages.
Hadi Hezaveh,Ida Idayu Muhamad 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11
Genipin cross-linked kappa-carrageenan/hydroxyethyl cellulose hydrogels were prepared and the effect of cross-linking on hydrogels characteristics was investigated. Swelling and transform mechanisms of both native and cross-linked gels in different pH were also studied. We found that the concentration of genipin affects the physical stability of gels. The optimum concentration that a cross-linked hydrogel molecular structure can be in its most stable form is also discussed. Native hydrogels exhibited more swelling in alkaline medium than acidic and neutral; however, by increasing the cross-linker concentration, the swelling ability in neutral medium increased so that genipin cross-linked hydrogels could swell in pH 7 more than in pH 1.2 and 12. Fourier transform infrared spectroscopy (FTIR) was applied to study the formation of new bonding due to genipin reactions and explain hydrogels’ stability in various concentrations. Differential scanning calorimetry (DSC) measurements reveal that by increasing genipin, the gel ability to hold water increases to some point and then decreases due to less structural stability. X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) tests were performed to study the crystallinity changes and microstructure of hydrogels. Finally, the power law model was applied to study the transform mechanism of hydrogels.
A modified replacement beam for analyzing building structures with damping systems
Hadi Moghadasi Faridani,Antonio Capsoni 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.5
This paper assesses efficiency of the continuum method as the idealized system of building structures. A modified Coupled Two-Beam (CTB) model equipped with classical and non-classical damping has been proposed and solved analytically. In this system, complementary (non-classical) damping models composed of bending and shear mechanisms have been defined. A spatial shear damping model which is non-homogeneously distributed has been adopted in the CTB formulation and used to equivalently model passive dampers, viscous and viscoelastic devices, embedded in building systems. The application of continuum-based models for the dynamic analysis of shear wall systems has been further discussed. A reference example has been numerically analyzed to evaluate the efficiency of the presented CTB, and the optimization problems of the shear damping have been finally ascertained using local and global performance indices. The results reveal the superior performance of non-classical damping models against the classical damping. They show that the critical position of the first modal rotation in the CTB is reliable as the optimum placement of the shear damping. The results also prove the good efficiency of such a continuum model, in addition to its simplicity, for the fast estimation of dynamic responses and damping optimization issues in building systems.