Dynamic response of functionally graded annular/circular plate in contact with bounded fluid under harmonic load

Yousefzadeh, Sh.,Jafari, A.A.,Mohammadzadeh, A.,Najafi, M. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.5

In this study, the dynamic response of a functionally graded material (FGM) circular plate in contact with incompressible fluid under the harmonic load is investigated. Analysis of the plate is based on First-order Shear Deformation Plate Theory (FSDT). The governing equation of the oscillatory behavior of the fluid is obtained by solving Laplace equation and satisfying its boundary conditions. A new set of admissible functions, which satisfy both geometrical and natural boundary conditions, are developed for the free vibration analysis of moderately thick circular plate. The Chebyshev-Ritz Method is employed together with this set of admissible functions to determine the vibrational behaviors. The modal superposition approach is used to determine the dynamic response of the plate exposed to harmonic loading. Numerical results of the force vibrations and the effects of the different geometrical parameters on the dynamic response of the plate are investigated. Finally, the results of this research in the limit case are compared and validated with the results of other researches and finite element model (FEM).

Road profile estimation using neural network algorithm

Mahdi Yousefzadeh,Shahram Azadi,Abbas Soltani 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.3

This paper more specifically focuses on the estimation of a road profile (i.e., along the "wheel track"). Road profile measurements have been performed to evaluate the ride quality of a newly constructed pavement, to monitor the condition of road networks in road management systems, as an input to vehicle dynamic systems, etc. The measurement may be conducted by a slow-moving apparatus directly measuring the elevation of the road or using a means that measures surface roughness at highway speeds by means of accelerometers coupled with high speed distance sensors, such as laser sensors or using a vehicle equipped with a response-type road roughness measuring system that indirectly indicate the user's feelings of the ride quality. This paper proposes a solution to the road profile estimation using an artificial neural network (ANN) approach. The method incorporates an ANN which is trained using the data obtained from a validated vehicle model in the ADAMS software to approximate road profiles via the accelerations picked up from the vehicle. The study investigates the estimation capability of neural networks through comparison between some estimated and real road profiles in the form of actual road roughness and power spectral density.

Dynamic response of functionally graded annular/circular plate in contact with bounded fluid under harmonic load

Sh. Yousefzadeh,A. A. Jafari,A. Mohammadzadeh,M. Najafi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.5

In this study, the dynamic response of a functionally graded material (FGM) circular plate in contact with incompressible fluid under the harmonic load is investigated. Analysis of the plate is based on First-order Shear Deformation Plate Theory (FSDT). The governing equation of the oscillatory behavior of the fluid is obtained by solving Laplace equation and satisfying its boundary conditions. A new set of admissible functions, which satisfy both geometrical and natural boundary conditions, are developed for the free vibration analysis of moderately thick circular plate. The Chebyshev-Ritz Method is employed together with this set of admissible functions to determine the vibrational behaviors. The modal superposition approach is used to determine the dynamic response of the plate exposed to harmonic loading. Numerical results of the force vibrations and the effects of the different geometrical parameters on the dynamic response of the plate are investigated. Finally, the results of this research in the limit case are compared and validated with the results of other researches and finite element model (FEM).

Using Taguchi design of experiments for the optimization of electrospun thermoplastic polyurethane scaffolds

Nezadi, Maryam,Keshvari, Hamid,Yousefzadeh, Maryam Techno-Press 2021 Advances in nano research Vol.10 No.1

Electrospinning is a cost-effective and versatile method for producing submicron fibers. Although this method is relatively simple, at the theoretical level the interactions between process parameters and their influence on the fiber morphology are not yet fully understood. In this paper, the aim was finding optimal electrospinning parameters in order to obtain the smallest fiber diameter by using Taguchi's methodology. The nanofibers produced by electrospinning a solution of Thermoplastic Polyurethane (TPU) in Dimethylformamide (DMF). Polymer concentration and process parameters were considered as the effective factors. Taguchi's L9 orthogonal design (4 parameters, 3 levels) was applied to the experiential design. Optimal electrospinning conditions were determined using the signal-to-noise (S/N) ratio with Minitab 17 software. The morphology of the nanofibers was studied by a Scanning Electron Microscope (SEM). Thereafter, a tensile tester machine was used to assess mechanical properties of nanofibrous scaffolds. The analysis of DoE experiments showed that TPU concentration was the most significant parameter. An optimum combination to reach smallest diameters was yielded at 12 wt% polymer concentration, 16 kV of the supply voltage, 0.1 ml/h feed rate and 15 cm tip-to-distance. An empirical model was extracted and verified using confirmation test. The average diameter of nanofibers at the optimum conditions was in the range of 242.10 to 257.92 nm at a confidence level 95% which was in close agreement with the predicted value by the Taguchi technique. Also, the mechanical properties increased with decreasing fibers diameter. This study demonstrated Taguchi method was successfully applied to the optimization of electrospinning conditions for TPU nanofibers and the presented scaffold can mimic the structure of Extracellular Matrix (ECM).

Practical Focus on American Diabetes Association/ European Association for the Study of Diabetes Consensus Algorithm in Patients with Type 2 Diabetes Mellitus: Timely Insulin Initiation and Titration (Iran- AFECT)

Mohammad Ebrahim Khamseh,Gholamreza Yousefzadeh,Zahra Banazadeh,Sahar Ghareh 대한당뇨병학회 2017 Diabetes and Metabolism Journal Vol.41 No.1

Background The aim of this study was to evaluate the safety and effectiveness of insulin glargine in a large population from a variety of clinical care in Iranian people with type 2 diabetes mellitus (T2DM) and to measure the percentage of patients achieving glycosylated hemoglobin (HbA1c) <7% by the end of 24 weeks of treatment in routine clinical practice. Methods This study was a 24 week, observational study of patients with T2DM, for whom the physician had decided to initiate or to switch to insulin glargine. The safety and efficacy of glargine were assessed at baseline and at week 24. Results Seven hundred and twenty-five people with T2DM (63% female) including both insulin naïve and prior insulin users were recruited in this study. The mean age of the participants was 54.2±11.2 years, and the mean HbA1c level was 8.88%±0.93% at baseline. By the end of the study, 27% of the entire participants reached to HbA1c target of less than 7% and 52% had HbA1c ≤7.5%. No serious adverse event was reported in this study. Furthermore, overall hypoglycemia did not increase in prior insulin users and the entire cohort. In addition, body weight did not change in participants while lipid profile improved significantly. Conclusion Treatment with insulin glargine could improve glycemic control without increasing the risk of hypoglycemic events in people with T2DM. In addition, a significant clinical improvement was observed in lipid profile.

Design, Modeling and Control of a Simulator of an Aircraft Maneuver in the Wind Tunnel Using Cable Robot

Hami Tourajizadeh,Mahdi Yousefzadeh,Ali Keymasi Khalaji,Mahdi Bamdad 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.5

In this paper, a new controllable simulator is proposed and modeled by which, experimental tests of the aircraft’s models can be performed in wind tunnels with a high level of accuracy. These tests are unavoidable in order to extract the aerodynamic characteristics of the plant and optimize its related profiles. Drag and lift coefficients of the aircraft have a significant effect on the static and also dynamic maneuver of the airplane and thus evaluating these characteristics before manufacturing the aircraft are highly valuable in order to optimize the profile of their structures. To realize the mentioned target experimental tests can provide more accurate and trustable results rather than computer simulations. In order to conduct the wind tunnel tests with the highest accuracy, it is extremely significant to decrease any source of error such as disturbing drag forces. Thus it is required to control and manipulate the model of the aircraft with the aid of a mechanism that not only has the minimum effect on the drag force but also provides the least amount of deviation corresponding to drag forces. To do so, in this paper, a new cable robot is proposed as a proper candidate mechanism by which the disturbing drag force of the tunnel wind is minimum as a result of exact control of all of six spatial Degrees of Freedom (DOFs). Also, cables have the least cross-section area against the wind force and therefore the error of disturbing drags could be minimized. Moreover, there are other advantages for these kinds of robots such as low weight and cost, high load carrying capacity, and easy assembling capability. By proper design of the cables and actuators, it is possible to control all of the degrees of freedom of the end-effector during the dynamic maneuver of the aircraft and so it possible to perform all of the required static and dynamic tests of the plant. Therefore, in this paper first, the proper mechanism is designed and its related kinematics and kinetics modeling is provided. Besides, a robust controller is designed based on Non-Singular Fast Terminal Sliding Mode (NFTSM) to control the aircraft maneuver in presence of wind disturbance and complete the test process. All of the mentioned claims are verified by MATLAB simulations and the results confirm the mentioned expectancies.

Effect of Ni on Microstructure and Creep Behavior of A356 Aluminum Alloy

Mohammad Varmazyar,Shahrouz Yousefzadeh,Sheikhi Mohammad Morad 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3

The effect of 0.25, 0.5 and 1 wt% Ni addition on the impression creep behavior of the cast A356 alloy was investigated. Optical and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS) were used forexamination of the microstructure. The alloy’s creep properties were investigated using the impression creep technique undernormalized stress of 0.022–0.03 (corresponding to 600–675 MPa) and temperature of 473–513 K. The results showed thatthe creep properties of A356 alloy were improved by the addition of Ni. The improved creep properties were attributed tothe modification of eutectic silicon and the formation of Ni-rich intermetallics. Calculating the values of stress exponent (n)and creep activation energy (Q) indicated that the dominant mechanism was the lattice self-diffusion climb controlled andNi had no effect on the creep mechanism.

Two-dimensional materials in semiconductor photoelectrocatalytic systems for water splitting

Faraji, Monireh,Yousefi, Mahdieh,Yousefzadeh, Samira,Zirak, Mohammad,Naseri, Naimeh,Jeon, Tae Hwa,Choi, Wonyong,Moshfegh, Alireza Z. The Royal Society of Chemistry 2019 Energy & environmental science Vol.12 No.1

<P>Hydrogen (H2) production <I>via</I> solar water splitting is one of the most ideal strategies for providing sustainable fuel because this requires only water and sunlight. In achieving high-yield production of hydrogen as a recyclable energy carrier, the nanoscale design of semiconductor (SC) materials plays a pivotal role in both photoelectrochemical (PEC) and photocatalytic (PC) water splitting reactions. In this context, the advent of two-dimensional (2D) materials with remarkable electronic and optical characteristics has attracted great attention for their application to PEC/PC systems. The elaborate design of combined 2D layered materials interfaced with other SCs can markedly enhance the PEC/PC efficiencies <I>via</I> bandgap alteration and heterojunction formation. Three classes of 2D materials including graphene, transition metal dichalcogenides (TMDs), and graphitic carbon nitride (g-C3N4), and their main roles in the photoelectrocatalytic production of H2, are discussed in detail herein. We highlight the various roles of these 2D materials, such as enhanced light harvesting, suitable band edge alignment, facilitated charge separation, and stability during the water splitting reaction, in various SC/2D photoelectrode and photocatalytic systems. The roles of emerging 2D nanomaterials, such as 2D metal oxyhalides, 2D metal oxides, and layered double hydroxides, in PEC H2 production are also discussed.</P>

Pros and cons of the health transformation program in Iran:

Enayatollah Homaie Rad,Vahid Yazdi-Feyzabadi,Shahrokh Yousefzadeh-Chabok,Abolhasan Afkar,Ahmad Naghibzadeh 한국역학회 2017 Epidemiology and Health Vol.39 No.-

OBJECTIVES: The health transformation program was a recent reform in the health system of Iran that was implemented in early 2014. Some of the program’s important goals were to improve the equity of payments and to reduce out-of-pocket (OOP) payments and catastrophic health expenditures (CHE). In this study, these goals were evaluated using a before-and-after analysis. METHODS: Data on household income and expenditures in Guilan Province were gathered for the years 2013 and 2015. OOP payments for outpatient, inpatient, and drug services were calculated, and the results were compared using the propensity score matching technique after adjusting for confounding variables. Concentration indices and curves were added to quantify changes in inequity before and after the reform. The incidence of catastrophic expenditures was then calculated. RESULTS: Overall and outpatient service OOP payments increased by approximately 10 dollars, while for other types of services, no significant changes were found. Inequity and utilization of services did not change after the reform. However, a significant reduction was observed in CHE incidence (5.75 to 3.82%). CONCLUSIONS: The reform was successful in decreasing the incidence of CHE, but not in reducing the monetary amount of OOP payments or affecting the frequency of health service utilization.

Shear Buckling Analysis of Steel Flat and Corrugated Web I-girders

Farhad Riahi,Alaeddin Behravesh,Mikaeil Yousefzadeh Fard,Arastoo Armaghani 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.12

One of the parameters of the economic design of steel I-girders is the use of thin webs. However, in large spans, the use of deep Igirders with thin web leads to the buckling of the web. In order to achieve out-of-plane stiffness and shear buckling resistance without the use of stiffeners or increasing the thickness of the webs, one possible way is to use corrugated plates in the I-girder web. To understand, shear stress distribution of the web a series of three-point load test was performed on four types of the web; (flat, trapezoidal-, sinusoidal-, and the zigzag-corrugated). A non-linear FE analysis method was used to obtain the shear stress distribution in a flat and corrugated web, since it was not possible to obtain the shear stress distribution from the experimental investigation. Based on this research, it was found that the main failure modes of the current models are yielding or shear buckling of the web when it is under the shear. In addition, it shows that the failure of all beams occurred due to shear buckling of the web without any interaction of the flange. In the other hand, the shear stress along the side of the flange is nearly zero; it is clear that the web takes almost all the shear force. The nonlinear analysis results show that shear stress is maximum and uniformly distributed on the web before the buckling. After buckling, the volume of shear stress is reduced and distributed unevenly.According to the results, there are three types of shear buckling: local, global, and interactive in models.