Amirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601A hybrid optimal-base fuzzy-proportional-integral-derivative controller for vibration mitigation of structural system against earthquake193214408710.22060/ajme.2020.17706.5868ENSeyed MahdiHadad BaygiKhorasan Institute of Higher EducationJournal Article20200112This paper proposes an experimental investigation of a four-story structure that is connected to a shaking table. The investigated shaking table is designed with a particular method to produce any kind of vibration amplitude. Also, the whale optimization algorithm is used for the identification of the experimental structure parameters such as mass, stiffness, and damping to show the adaptation of the results collected from the identified model on the results achieved from the linear model. The other idea of this paper is to suggest a novel control strategy that is established by combining proportional-integral-derivative and fuzzy logic control, using an optimization procedure called whale optimization algorithm for optimum tuning of controller coefficients, the hybrid control method is designed. The main objective of the hybrid optimal-based fuzzy-proportional-integral-derivative controller is to reduce the displacement of isolation system without allowing a significant increase in the acceleration of superstructure for both far-field and near-field earthquake excitations. The proposed control algorithm is designed and developed on a four-story shear frame, which contains an active tuned mass damper on each level. Numerical simulations show that the proposed controller which is a combination of two controllers better mitigates the seismic responses of a smart structure excited by a range of real-data earthquakes.https://ajme.aut.ac.ir/article_4087_d2a2c1da2acde3ed27003dba9c3c1ccc.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Force frequency effect in square quartz crystals215226418610.22060/ajme.2020.17774.5872ENMohammad MostafaMohammadiزنجان-مهندسی- گروه مهندسی مکانیکMohsenHamediDepartment of Mechanical Engineering
University of TehranJournal Article20200122In this investigation, the force-frequency effect in a square AT-Cut quartz resonator is studied. Based on the force-frequency effect, by insertion of diametrical forces, the natural frequency of thickness shear vibration mode in AT-Cut quartz resonators is changed. This criterion is of importance in designing quartz resonators and force sensors. In this paper, the frequency change of a square AT-Cut quartz crystal subjected to a pair of opposing forces on different points of its edge is studied experimentally. Also, the force-frequency effect in the square crystal is modeled by a previously developed mathematical-finite element model. The accuracy of the model is verified by the experimental results. Then, the model is applied for evaluating the force-frequency effect in the AT-Cut crystal, and the frequency shifts in different loading configurations are obtained. The new loading configurations are produced by moving the loading points along the edges, and by rotating the edges of the crystal around its thickness axis. Also, the distributed loading tests are performed on the crystal. Based on this, the loading configurations with maximum and minimum frequency shifts are obtained. Moreover, the design of quartz crystal force sensors having high sensitivity and also the crystal oscillator with high-frequency stability are discussed.https://ajme.aut.ac.ir/article_4186_0ab922ba3e948387b4b2a85fcb83d194.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Support parameters design of Jeffcoat rotor using nonlinear energy sink & H∞ method227238409810.22060/ajme.2020.17847.5876ENHamidrezaHeidariFaculty of Mechanical Engineering, Malayer University, Malayer, IranPedramSafarpourFaculty of Mechanical & Energy Engineering, Shahid Beheshti University, Tehran, IranJournal Article20200210Rotating machinery support design with the aim of robustly absorbing transient disturbances over a broad range of frequencies has significant importance regarding the various applications of this machinery. Hence, the nonlinear energy sink may be regarded as an efficient passive absorber, possessing adaptivity to the frequency content of vibrations of the primary system. This paper studies the effect of nonlinear energy sinks on the vibration suppression of a flexible rotor supported by a linear damping and an essentially nonlinear stiffness. First, the governing equations for the Jeffcott rotor model mounted on flexible supports are derived and numerically solved. Then, the optimal parameters for the linear supports have been analytically achieved by H<sub>∞</sub> optimization procedure. Numerical simulations have been performed to optimize the nonlinear energy sink parameters by using Matlab software in order to obtain the optimum performance for vibration reduction. Moreover, the H<sub>∞</sub> optimum parameters such as tuning frequency and damping ratios are expressed based on fixed-point theory to minimize the rotor amplitudes. It is proven by numerical simulations that the system optimization design can effectively improve the synchronous unbalance response.https://ajme.aut.ac.ir/article_4098_eca89c0554ce99eaf250504971789ede.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Finite duration HIV treatment using mixed antiretroviral therapy and immunotherapy239254408510.22060/ajme.2020.17988.5880ENMostafaNazariDepartment of Mechanical Engineering, Shahrood University of Technology, Shahrood, Iran.MahnazSharifniaFaculty of mechanical and mechatronics engineering, Shahrood University of TechnologyHabibAhmadiFaculty of mechanical and mechatronics engineering, Shahrood University of TechnologyJournal Article20200224Proposing a finite duration HIV treatment strategy is the main goal of the presented paper. Long-term treatments cause many problems, such as drug resistance. Latently infected cells have an important role in HIV dynamics. The used HIV model not only consists of target cells and infected cells and viruses but also includes latently infected cells. It is shown that the initial population of latently infected cells affects the final population of viruses. The dynamics of the model are examined by extracting equilibrium points and their stability. Two types of equilibrium points are derived, virus-free and viral equilibrium points. It is proved that the existence of a stable virus-free equilibrium point is essential for finite duration treatment. Also, the effect of immune system ability in HIV treatment is explored by considering the effect of changing the parameters of the system in its dynamics. It is shown that in some immune system abilities, HIV is cured without any external treatment. The number of equilibrium points of the system changes with changes in the immune system ability. Based on this fact, a novel mixed antiretroviral therapy and immunotherapy are presented. Antiretroviral therapy affects the states of the system, and immunotherapy affects the parameters of the system. The simulation results show the effectiveness of the novel presented treatment strategy.https://ajme.aut.ac.ir/article_4085_fc76150735dde1d2d860aeb77ee2009e.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Application of alumina/graphene nanocomposite to enhance the surface quality of Al7175-T74 specimens255264409310.22060/ajme.2020.17420.5861ENSamanKhalilpourazaryFaculty of Mechanical Engineering, Urmia University of Technology, Urmia, IranSeyed SalarMeshkatFaculty of Chemical Engineering, Urmia University of Technology, Urmia, IranJavadSalehiFaculty of Mechanical Engineering, Urmia University of Technology, Urmia, IranJournal Article20191124The burnishing process is one of the non-removal finishing processes, which is employed to enhance surface quality, corrosion property, and surface microhardness. In this study, the dry burnishing process was performed on the surface of Al7175-T74 specimens. Furthermore, nanofluid containing alumina/graphene nanocomposite was employed to perform the Nano burnishing process on the same specimens. The results show that the arithmetic surface roughness parameter in nanofluid burnished samples is decreased by approximately 0.277 , 0.233 and 0.345 for the penetration depths of 0.2, 0.3, and 0.4mm compared to those of dry burnishing process. Moreover, microhardness values in Nano and dry burnishing processes are directly related to the penetration depth parameter. The results reveal that the values of microhardness for the nanofluid burnished samples with four penetration depths of 0.2, 0.3, 0.4, and 0.5 mm are increased about 3, 28, 42, and 39 Vickers comparing to those values of the dry burnishing process. The results prove that the minimum surface roughness and maximum microhardness values can be reached in Nano and dry roller burnishing processes at the penetration depth of 0.4 mm. Eventually, analyzing elements distribution on the surface of burnished aluminum alloy specimens confirm that the alumina/graphene nanocomposite is embedded in the burnished surfaces during Nano burnishing process.https://ajme.aut.ac.ir/article_4093_101951fe7ebe7bd8c77d14f75746b4bc.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Thermal stability analysis of cylindrical thin-walled tanks subjected to lateral fire loading265280416510.22060/ajme.2020.18187.5888ENAlirezaPourkeramatSchool of Mechanical Engineering, University of Tehran, Tehran, IranAli RezaDanesh Mehrدانشگاه تهران*مهندسی مکانیکKiyarashAminfarSchool of Mechanical Engineering, University of Tehran, Tehran, IranSinaJaliliFaculty of Mechanical Engineering, Sahand University of Technology, Tabriz, IranJournal Article20200331Thin-walled cylinders are widely used as fluid storage tanks, such as water, which is a vital component in extinguishing facilities. Due to the thinness essence of these structures, the stability performance will be put in peril when exposed to various destabilizing side loads. Lateral thermal loads resulting from side fires can lead to unstable behavior of the tanks. The combustion and fire formation are multi-physics phenomena and require a multi-phase fluid perspective to analyze them more closely. In this study, to enhance the analysis's accuracy, the large eddy simulation approach is used to model the fire and estimate its thermal effects on the adjacent structures. The results are consequently utilized for nonlinear stability analysis. The fire simulation results for empty and half-filled tanks are exploited to study the influence of various structural parameters such as geometrical imperfection, roof thickness, and the shell thickness distribution on the critical buckling temperature and instability time. The results reveal that the structure's lateral thermal stability will be maximized at a specific ratio of the roof to the wall thickness. The stepped shell profile, as well as the geometrical imperfection of each configuration, can reduce the critical threshold by up to 40% and weaken the structure against heat. The present research outcomes would help the structural optimizing process of a fire-extinguishing tank subjected to fire-induced instability.https://ajme.aut.ac.ir/article_4165_a7f0d2b95c60161b3f3c82f764b1d1c9.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Evaluation of energy potential of municipal solid waste gasification in different regions of Iran by using a modified equilibrium thermodynamic model281296408410.22060/ajme.2020.18135.5885ENAliBahariUniversity of guilanKazemAtashkariگیلان*مهندسی مکانیکJavadMahmoudiMehrgulianJournal Article20200318Municipal solid waste is the largest waste stream around the world and has a great potential for generating synthetic gas. An improved numerical model is used based on equilibrium thermodynamics to predict the composition of the municipal solid waste gasification products. To validate the superiority of the model, the results are compared and verified against some experimental studies. The developed model is then used to study the potential of energy extraction from solid waste in Iran as a case study. For this purpose, Iran is divided into ten separate zones, and the chemical composition of the wastes in each region is determined based on the type and amount of the waste compounds. Next, the effects of some important factors such as the amount of moisture content, environmental humidity, and equivalence ratio are investigated. The results show that at the equivalence ratio of 0.3, Khuzestan and Zagros regions have the highest and the lowest heating values of the produced synthetic gas with the cold gas efficiency of 20% and 16.5%, respectively. At the equivalence ratio of 0.6, the same qualitative results are obtained; however, the mentioned values of cold gas efficiency for Khuzestan and Zagros decrease to 14.8% and 13.8%, respectively.https://ajme.aut.ac.ir/article_4084_7ac71d433f282034e088473244df8c02.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Comparative thermoeconomic analysis of using different jet fuels in a turboshaft engine for aviation applications297312416810.22060/ajme.2020.17888.5877ENVahidZareUrmia university of thechnology0000-0003-4863-5024ShahramKhodaparastmechanical engineering, urmia university of technology, urmia, IranElnazShayanmechanical engineeringJournal Article20200209Fuel efficiency of helicopter and aircraft propulsion systems become more important in recent years due to the rising fuel costs and environmental impacts of aviation emissions. In this regard, in the present study, the use of three conventional types of jet fuels in a turboshaft engine is investigated from exergy and exergoeconomic viewpoints. Component-based exergy and cost calculations are accomplished by developing thermodynamic and exergoeconomic models which their accuracy is validated using the available experimental data in the literature. To examine the effects of important design/operating variables on the engine performance, a parametric study is performed for the considered fuels to assess exergy and economic performance. Also, the influence of flight altitude is investigated on the engine performance in terms of net output power, exergy efficiency, and unit cost of power. The results indicate that, JP-4 jet fuel yields better performance for considered turboshaft engine in terms of exergy efficiency and unit cost of power. It is shown that the engine exergy efficiency for JP-4 fuel is around 9 % and 6% higher than that for JP-5 and JP-8 fuels, respectively.<br /><strong> </strong>https://ajme.aut.ac.ir/article_4168_e46bc064f8e92ac2c404b9871b2a4ef2.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Optimization Techniques for Design a shell and tube heat exchanger from an economic viewpoint313328409210.22060/ajme.2020.18027.5882ENHabibKarimiDepartment of mechanical Eng., Islamic Azad university, Roudsar and Amlash branch, Roudsar, IranHoseinAhmadi Danesh AshtianiDepartment of mechanical engineering, South Tehran Branch, Islamic Azad University, Tehran, IranCyrusAghanajafikhejenasirJournal Article20200301This paper aims to minimize the total annual cost for a shell and tube heat exchanger based on optimization algorithms. The total annual cost is the sum of the initial cost for the construction of the heat exchanger and the cost of power consumption in the shell and tube heat exchanger. The total annual cost is the objective function, which is minimized. This research uses three optimization algorithms including particle swarm optimization, genetic algorithm, and differential evolution, and three optimization variables including shell’s inside diameter, tubes’ outer diameter, and baffle spacing. Three different studies have been used to compare the results. The results demonstrated that the differential evolution algorithm achieved the most decline in the total annual cost compared to other optimization algorithms. Using differential evolution algorithm, the total annual cost was decreased about 30% in study 1 and about 28.1% in study 2 compared with literature, respectively. The reduction in the total operating cost is about 47.7% for differential evolution algorithm, 45.7% for particle swarm optimization, and 45.3% for genetic algorithm relative to the results reported in the literature for case study 3. Results were compared with at least eight works directly and have been demonstrated in this research.https://ajme.aut.ac.ir/article_4092_77340c2e00e9e6ad1b2784dad06291ea.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29375220210601Synthesis of a pure FeAl with a density greater than 95% of theoretical density by optimizing effective factors329340429510.22060/ajme.2021.18021.5881ENRaziehKhoshhalDepartment of Material Science and Engineering, Birjand University of Technology, Birjand, IranHojjatMirzaei-GhasabeDepartment of Materials Science and Engineering, Iran University of Science and TechnologyAliHosseinzadehDepartment of Mechanics, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran0000-0002-1090-2943Journal Article20200301In this study, the FeAl with a density greater than 95% of the theoretical density was synthesized by optimizing the compacting pressure, the particle size of iron and aluminum, and the pre-heating temperature. To do so, the products of the samples which were examined by the change of the particle size of 10µm and 50µm, the pre-heating temperatures of 25°C, 287°C and 550°C and the compacting pressures of 400MPa, 500MPa, and 600MPa, were studied. According to the appearance, composition, density, hardness, and oxidation resistance, the optimum sample was determined. The optimal FeAl had a density of more than 95% of the theoretical density, which was prepared using the particle size of 10/10 of iron and aluminum, the pre-heating temperature of 550°C, and the compacting pressure of 500 MPa. The duration of the pre-heating and the synthesis was also 5 and 3h, respectively. It was found that without pre-heating, there is no possibility of producing a compact and dense product. It was also found that the particle size of the iron is more effective than the particle size of aluminum to achieve the qualified FeAl product.https://ajme.aut.ac.ir/article_4295_a57d48399922b03419153a9760c5ce53.pdf