Consistent couple-stress theory for free vibration analysis of Euler-Bernoulli nano-beams made of arbitrary bi-directional functionally graded materials

Mohammad Zamani Nejad,Amin Hadi,Ali Farajpour 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.2

In this paper, using consistent couple stress theory and Hamilton's principle, the free vibration analysis of Euler- Bernoulli nano-beams made of bi-directional functionally graded materials (BDFGMs) with small scale effects are investigated. To the best of the researchers' knowledge, in the literature, there is no study carried out into consistent couple-stress theory for free vibration analysis of BDFGM nanostructures with arbitrary functions. In addition, in order to obtain small scale effects, the consistent couple-stress theory is also applied. These models can degenerate into the classical models if the material length scale parameter is taken to be zero. In this theory, the couple-tensor is skew-symmetric by adopting the skew-symmetric part of the rotation gradients as the curvature tensor. The material properties except Poisson's ratio are assumed to be graded in both axial and thickness directions, which it can vary according to an arbitrary function. The governing equations are obtained using the concept of Hamilton principle. Generalized differential quadrature method (GDQM) is used to solve the governing equations for various boundary conditions to obtain the natural frequencies of BDFG nano-beam. At the end, some numerical results are presented to study the effects of material length scale parameter, and inhomogeneity constant on natural frequency.

Bending analysis of bi-directional functionally graded Euler-Bernoulli nano-beams using integral form of Eringen’s non-local elasticity theory

Mohammad Zamani Nejad,Amin Hadi,Arash Omidvari,Abbas Rastgoo 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.4

The main aim of this paper is to investigate the bending of Euler-Bernouilli nano-beams made of bi-directional functionally graded materials (BDFGMs) using Eringen‟s non-local elasticity theory in the integral form with compare the differential form. To the best of the researchers‟ knowledge, in the literature, there is no study carried out into integral form of Eringen‟s non-local elasticity theory for bending analysis of BDFGM Euler-Bernoulli nano-beams with arbitrary functions. Material properties of nano-beam are assumed to change along the thickness and length directions according to arbitrary function. The approximate analytical solutions to the bending analysis of the BDFG nano-beam are derived by using the Rayleigh-Ritz method. The differential form of Eringen‟s non-local elasticity theory reveals with increasing size effect parameter, the flexibility of the nano-beam decreases, that this is unreasonable. This problem has been resolved in the integral form of the Eringen‟s model. For all boundary conditions, it is clearly seen that the integral form of Eringen‟s model predicts the softening effect of the non-local parameter as expected. Finally, the effects of changes of some important parameters such as material length scale, BDFG index on the values of deflection of nano-beam are studied.

An exact solution for stresses and displacements of pressurized FGM thick-walled spherical shells with exponential-varying properties

Mohammad Zamani Nejad,Majid Abedi,Mohammad Hassan Lotfian,Mehdi Ghannad 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.12

Exact closed-form solutions have been derived for stresses and the displacements in thick spherical shells made of functionally graded materials with exponential-varying properties subjected to internal and external pressure. Poisson’s ratio is assumed to be constant. The obtained results show that the inhomogeneity properties of FGMs have a significant influence on the displacement and stresses distribution along the radial direction. A numerical solution using finite element method is also presented and good agreement was found between the analytical solutions and the solutions carried out through the FEM. The values used in this study are arbitrarily chosen to demonstrate the effect of inhomogeneity on displacements and stresses distributions.

Time-dependent mathematical modeling of binary gas mixture in facilitated transport membranes (FTMs): A real condition for single-reaction mechanism

Mohammad Mehdi Moftakhari Sharifzadeh,Abtin Ebadi Amooghin,Mona Zamani Pedram,Mohammad Reza Omidkhah 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.39 No.-

In this study, a comprehensive time-dependent mathematical model for gas separation through thefacilitated transport membranes (FTMs) is presented. The model results have been validated withindependent CO2/N2 binary gas mixture experiments in DEA-impregnated PVA membranes. In theproposed model, non-equal diffusion coefficients of the carrier/complex and equilibrium constant for thechemical reaction kinetics between the carrier/permeant in the FTM have been considered. In addition, amethod to compute the diffusion coefficients, which depend on the concentration of each component inthe FTM, is presented. Moreover, effect of carrier concentration, feed partial pressure, kinetics ofreversible chemical reactions and membrane performances depending on operating condition have beenanalyzed. Owing to accurate calculation of physical–chemical parameter involved, this model is muchmore executive comparing to previous works. In addition, the real condition of the reaction kinetics andinfluencing of diffusion parameters of the components in FTMs, have been investigated. The predictedselectivity and permeability revealed good conformity with experimental data; with standard deviation(SD) 8.57% and 12.87%, respectively. In conclusion, this model with significant validity would bepredictive in cases for the entire range of diffusion-limit to a chemical-limit regime where theexperimental data, geometry condition, physical–chemical property of parameters is not available.

The Effects of Magnesium Supplementation on Serum Magnesium and Calcium Concentration in Patients With Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Zamani Mohammad,Haghighat Neda 한국임상영양학회 2022 Clinical Nutrition Research Vol.11 No.2

The aim of this systematic review and meta-analysis was to summarize all the existing randomized controlled trials (RCTs) evidence and to evaluate the effects of magnesium supplementation on serum magnesium, calcium and urinary magnesium concentrations in patients with type 2 diabetes compared with the control. Two independent authors systematically searched online databases including Embase, Scopus, PubMed, and Web of Science from inception until 30th January 2022. RCTs complying with the inclusion criteria were included in this meta-analysis. The heterogeneity among the included studies was assessed using Cochrane’s Q test and I-square (I2) statistic. Data were pooled using a random-effects model and weighted mean difference (WMD) was considered as the overall effect size. Sixteen trials were included in this meta-analysis. Serum magnesium (mean difference, 0.15 mg/dL; 95% confidence interval [CI], 0.06 to 0.23; p = 0.001) and urinary magnesium (WMD, 1.99 mg/dL; 95% CI, 0.36 to 3.62; p = 0.017) concentrations were significantly increased after magnesium supplementation when compared with the control group. However, magnesium supplementation did not have any significant effect on serum calcium (WMD, −0.09 mg/dL; 95% CI, −0.27 to 0.08; p = 0.294) level when compared with the control group. This meta-analysis demonstrated that magnesium supplementation significantly increased Serum magnesium levels which may have played an indirect role in improved clinical symptoms in patients with type 2 diabetes.

Zn2+ PVC-based Membrane Sensor Based on 3-[(2-Furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one

Mohammad Reza Ganjali*,Hassan Ali Zamani,Parviz Norouzi,Mehdi Adib,Morteza Rezapour,Mohammad Aceedy 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.4

The 3-[(2-furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one (FTT) was used as an excellent ionophore in construction of a Zn2+ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 3% FTT and 5% sodium tetraphenyl borate (TBP). This membrane sensor shows very good selectivity and sensitivity towards Zn2+ over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The membrane sensor revealed a great enhancement in selectivity coefficients for Zn2+ ions, in comparison to the previously reported Zn2+ membrane sensors. Theoretical studies also showed the selective interaction of TFF and Zn2+ ions. The proposed membrane sensor exhibits a Nernstian behavior (with slope of 29.3 ± 0.3 mV per decade) over a wide concentration range (1.0´106-1.0´102) with a detection limit of 8.5´107 M (52 ng mL1). It shows relatively fast response time, in the whole concentration range (< 20 s), and can be used for at least 10 weeks in a pH range of 3.0-7.0. The proposed membrane sensor was successfully used in direct determination of Zn2+ ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.

Bending analysis of bi-directional functionally graded Euler-Bernoulli nano-beams using integral form of Eringen's non-local elasticity theory

Nejad, Mohammad Zamani,Hadi, Amin,Omidvari, Arash,Rastgoo, Abbas Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.4

The main aim of this paper is to investigate the bending of Euler-Bernouilli nano-beams made of bi-directional functionally graded materials (BDFGMs) using Eringen's non-local elasticity theory in the integral form with compare the differential form. To the best of the researchers' knowledge, in the literature, there is no study carried out into integral form of Eringen's non-local elasticity theory for bending analysis of BDFGM Euler-Bernoulli nano-beams with arbitrary functions. Material properties of nano-beam are assumed to change along the thickness and length directions according to arbitrary function. The approximate analytical solutions to the bending analysis of the BDFG nano-beam are derived by using the Rayleigh-Ritz method. The differential form of Eringen's non-local elasticity theory reveals with increasing size effect parameter, the flexibility of the nano-beam decreases, that this is unreasonable. This problem has been resolved in the integral form of the Eringen's model. For all boundary conditions, it is clearly seen that the integral form of Eringen's model predicts the softening effect of the non-local parameter as expected. Finally, the effects of changes of some important parameters such as material length scale, BDFG index on the values of deflection of nano-beam are studied.

Zn²⁺ PVC-based Membrane Sensor Based on 3-[(2-Furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one

Ganjali, Mohammad Reza,Zamani, Hassan Ali,Norouzi, Parviz,Adib, Mehdi,Rezapour, Morteza,Aceedy, Mohammad Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.4

The 3-[(2-furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one (FTT) was used as an excellent ionophore in construction of a $Zn^{2+}$ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 3% FTT and 5% sodium tetraphenyl borate (TBP). This membrane sensor shows very good selectivity and sensitivity towards $Zn^{2+}$ over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The membrane sensor revealed a great enhancement in selectivity coefficients for $Zn^{2+}$ ions, in comparison to the previously reported $Zn^{2+}$ membrane sensors. Theoretical studies also showed the selective interaction of TFF and $Zn^{2+}$ ions. The proposed membrane sensor exhibits a Nernstian behavior (with slope of 29.3 ${\pm}$ 0.3 mV per decade) over a wide concentration range (1.0 ${\times}$ $10^{-6}$-1.0 ${\times}$ $10^{-2}$) with a detection limit of 8.5 ${\times}$ $10^{-7}$ M (52 ng mL$^{-1}$). It shows relatively fast response time, in the whole concentration range ($\lt$ 20 s), and can be used for at least 10 weeks in a pH range of 3.0-7.0. The proposed membrane sensor was successfully used in direct determination of $Zn^{2+}$ ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.

Sensitive High-Resolution Melting Analysis for Screening of KRAS and BRAF Mutations in Iranian Human Metastatic Colorectal Cancers

Niya, Mohammad Hadi Karbalaie,Basi, Ali,Koochak, Aghigh,Tameshkel, Fahimeh Safarnezhad,Rakhshani, Nasser,Zamani, Farhad,Imanzade, Farid,Rezvani, Hamid,Adib sereshki, Mohammad Mahdi,Sohrabi, Masoud Rez Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.12

Background: Investigations of methods for detection of mutations have uncovered major weaknesses of direct sequencing and pyrosequencing, with their high costs and low sensitivity in screening for both known and unknown mutations. High resolution melting (HRM) analysis is an alternative tool for the rapid detection of mutations. Here we describe the accuracy of HRM in screening for KRAS and BRAF mutations in metastatic colorectal cancer (mCRCs) samples. Materials and Methods: A total of 1000 mCRC patients in Mehr Hospital, Tehran, Iran, from Feb 2008 to May 2012 were examined for KRAS mutations and 242 of them were selected for further assessment of BRAF mutations by HRM analysis. In order to calculate the sensitivity and specificity, HRM results were checked by pyrosequencing as the golden standard and Dxs Therascreen as a further method. Results: In the total of 1,000 participants, there were 664 (66.4%) with wild type and 336 (33.6%) with mutant codons 12 and/or 13 of the KRAS gene. Among 242 samples randomly checked for the BRAF gene, all were wild type by HRM. Pyrosequencing and Dxs Therascreen results were in line with those of the HRM. In this regard, the sensitivity and specificity of HRM were evaluated as 100%. Conclusion: The findings suggest that the HRM, in comparison with DNA sequencing, is a more appropriate method for precise scanning of KRAS and BRAF mutations. It is also possible to state that HRM may be an attractive technique for the detection of known or unknown somatic mutations in other genes.

Implementation of a 35KVA Converter Base on the 3-Phase 4-Wire STATCOMs for Medium Voltage Unbalanced Systems

Mohammad Hadi Karimi,Hassan Zamani,Khalil Kanzi,Qasem Vasheghani Farahani 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5

This paper discussed a transformer-less shunt static synchronous compensator (STATCOM) with consideration of the following aspects: fast compensation of the reactive power, harmonic cancelation and reducing the unbalancing of the 3-phase source side currents. The STATCOM control algorithm is based on the theory of instantaneous reactive power (P-Q theory). A self charging technique is proposed to regulate the dc capacitor voltage at a desired level with the use of a PI controller. In order to regulate the DC link voltage, an off-line Genetic Algorithm (GA) is used to tune the coefficients of the PI controller. This algorithm arranged these coefficients while considering the importance of three factors in the DC link voltage response: overshoot, settling time and rising time. For this investigation, the entire system including the STATCOM, network, harmonics and unbalancing load are simulated in MATLAB/SIMULINK. After that, a 35KVA STATCOM laboratory setup test including two parallel converter modules is designed and the control algorithm is executed on a TMS320F2812 controller platform.