Amirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29377120230301An investigation of pool boiling under alternating magnetic field and steady-state conditions318498210.22060/ajme.2022.21605.6041ENAbutalebRamezaniDepartment of Mechanical Engineering, Yazd University, Yazd, IranAhmadrezaFaghih KhorasaniDepartment of Mechanical Engineering, Yazd University, Yazd, IranAhmadrezaAyoobiDepartment of Aerospace Engineering, Shahid Sattari Aeronautical University of Science and Technology, Tehran, IranJournal Article20220717Applying an alternating magnetic field around the pool boiling region has various effects on the pool boiling's major characteristics. Steady-state pool boiling experiments were performed with deionized water under atmospheric pressure and the application of an alternating magnetic field. A nickel-chrome wire with a diameter of 0.1 mm was used as a heater. Two Helmholtz coils were used to generate the magnetic field. The effects of applying this field with intensities of 5.8, 8.9, and 13.3 mT on pool boiling parameters were investigated in experiments and compared to the state without a magnetic field. The results show that, in general, the application of a magnetic field shortens the pool boiling process and delays the start of the nucleate boiling regime. The critical heat flux did not vary significantly when alternating magnetic fields were used. In comparison to no magnetic field application, this parameter decreased by 1.38%, 2.31%, and 3.33% at magnetic field intensities of 5.8, 8.9, and 13.3 mT. But the boiling heat transfer coefficient has increased to a maximum of 47% at the critical heat flux point. The Lorentz force acting on water molecules reduced the number of bubbles surrounding the wire heater, allowing the heat produced to be transferred to the surrounding liquid more quickly. As a result, the heat transfer coefficient increased with increasing magnetic field strength.https://ajme.aut.ac.ir/article_4982_8e0384779e58ce2af40eb365b318cc32.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29377120230301Investigation on performance improvement of a fully-actuated quadrotor1940500210.22060/ajme.2022.21384.6034ENYaldaAslani DarandashiDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, IranRasulFesharakifardDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran0000-0003-4789-3603AbdolrezaOhadiDepartment of Textile Engineering, Amirkabir University of Technology, Tehran, IranJournal Article20220520Quadrotors provide exclusive performances like vertical landing and taking off, load carrying capacity, and possibility of remote control. A pertinent deficiency of them however concerns their underactuated configuration, which is one of the inherent characteristics of these robots. A dependency between different movements of quadrotor is unavoidable due to this characteristic. To eliminate the dependencies between linear and rotational motions and so increase the number of controllable degrees of freedom, a novel configuration has been presented for the fully-actuated quadrotor. The rotors have the ability to rotate around two perpendicular directions and two degrees of freedom have been added to the system. The motion dependencies between linear and angular degrees are omitted. To investigate the capability of the fully-actuated quadrotor, the novel configuration is introduced and the capabilities of this configuration in eliminating movement dependencies are discussed. To this end, after extracting the motion equations governing the fully-actuated quadrotor using Newton-Euler method and applying a proportional-derivative controller to the model, the performance of this configuration in eliminating the motion dependencies is compared against a conventional underactuated type. It is shown that this configuration is capable of eliminating motion dependencies to a great extent within various simulation results. Finally, by designing a back-stepping controller and applying different trajectories to the proposed fully-actuated quadrotor, its motion capabilities and limitations are thoroughly investigated.https://ajme.aut.ac.ir/article_5002_415585bd389b69659223807d77a96791.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29377120230301Simultaneous impacts of acoustic and inertial forces on the separation of microparticles4150508410.22060/ajme.2023.21665.6042ENZahraTaheriDepartment of Mechanical Engineering, Shahrekord University, Shahrekord, IranMortezaBayarehDepartment of Mechanical Engineering, Shahrekord University, Shahrekord, IranBehzadGhasemiDepartment of Mechanical Engineering, Shahrekord University, Shahrekord, IranMohsenNazemi AshaniDepartment of Mechanical Engineering, Shahrekord University, Shahrekord, IranJournal Article20220806The isolation of microparticles plays a crucial role in various applications, including biological and medical sciences. In this paper, the separation of polystyrene (PS) and polymethyl methacrylate (PMMA) particles suspended in water is simulated using the acoustic field and channel geometry. The microchannel consists of two parts, a curve-shaped and a straight part. Passive separation occurs in the curve-shaped section due to the flow rotation in the microchannel, and the acoustic force acts and enhances the separation efficiency in the straight part. The acoustic field is created by a pair of aluminum transducers on a piezoelectric substrate. In this study, firstly, the separation of microparticles is done using a microchannel without an acoustic field, leading to a separation efficiency of 81%. The acoustic force is then applied to the microchannel and, the maximum separation efficiency of 94% is obtained. It is observed that the separation efficiency is directly related to the frequency of the acoustic field and inversely related to the inlet flow rate. It should be noted that there is an optimal value for the applied frequency due to the specific value of the channel width. Also, the amount of separation efficiency is improved by enhancing the inlet power. It is observed that as the distance between transducers and microchannels is enhanced, the separation efficiency is reduced.https://ajme.aut.ac.ir/article_5084_a714ec6796f638ba4d5792f78dccd134.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29377120230301The use of copper as an accelerator for the formation of titanium aluminide intermetallic compounds5160509510.22060/ajme.2023.21934.6050ENRaziehKhoshhalDepartment of Material Science and Engineering, Birjand University of Technology, Birjand, IranSeyed VahidAlavi Nezhad Khalil AbadDepartment of Civil Engineering, Birjand University of Technology, Birjand, IranJournal Article20221113Titanium aluminides have received much attention due to their suitable properties such as lightness, maintaining strength at high temperatures, and resistance to corrosion and oxidation. Therefore, titanium aluminides and their composite play a key role in the industry, especially in urban transportation and aviation industries. The melting of aluminum is recognized as the first step of the titanium aluminide formation process from elemental powders or raw materials of TiO<sub>2</sub> and Al. Facilitating the aluminum smelting could be a contributing factor to accelerating the titanium aluminide-generating procedure. Selecting copper as an agent to reduce the melting point of aluminum is based on the binary phase diagram of Al-Cu in which a eutectic transformation is obvious. Different molar ratios of copper were added to the raw materials of aluminum and titania. Then the resulting compressed powder samples were subjected to heat treatment. It was found that up to a certain molar ratio, copper could reduce aluminum's melting temperature and promote the formation of titanium aluminide intermetallic compounds. The optimal amount of copper (<em>0.2</em>) has also greatly contributed to the uniformity and homogeneity of the composite structure. In general, in this research, the effect of copper on the production of titanium aluminide has been discussed both theoretically and practically. https://ajme.aut.ac.ir/article_5095_45be58330c9a2ac2bc408ec210820fab.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29377120230301Machine Vision System for Autonomous Guidance of Raisin-Collection Rover6172513010.22060/ajme.2023.21775.6045ENHamedRamezaniDepartment of Biosystems Engineering, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran0000-0002-0707-4403Mohammad HadiKhoshtaghazaDepartment of Biosystems Engineering, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran0000-0001-6754-6401SaeedMinaeiDepartment of Biosystems Engineering, Faculty of Agriculture, Tarbiat Modares University, Tehran, IranGholamrezaAkbarizadehDepartment of Electrical Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz,
Ahvaz, Iran0000-0003-0396-5601Journal Article20220916The development of autonomous vehicles based on machine vision system in various industries and agriculture is a challenging topic. In this study, the active-contour algorithm was utilized for path-tracking of an automatic raisin-collecting rover. For this purpose, the energy difference between the background and foreground levels is utilized to extract the boundary between raisins and the ground surface with good accuracy which is used for navigating the path. This was accomplished by developing a small unmanned rover equipped with four DC motors and a machine vision system. Field tests at the Sunny Raisin Court showed that the system was able to independently detect and navigate its path with an RMS error of 1.57 cm. The results of analysis of variance for accuracy of the path tracking showed that the effect of lighting conditions and speed on the accuracy was significant at the level of one percent.https://ajme.aut.ac.ir/article_5130_c64a9829fa4638ff5de86330dd227e35.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29377120230301Multi-Domain Modeling Platform for Electrical-Signature-Based Condition Monitoring of Motor-Driven Pumps7388511310.22060/ajme.2023.21285.6033ENZahraArasteSchool of Mechanical Engineering, University of Tehran, Tehran, IranMohammadJamimoghaddamSchool of Mechanical Engineering, University of Tehran, Tehran, IranAliSadighiSchool of Mechanical Engineering, University of Tehran, Tehran, IranJournal Article20220422Due to the vital role of motor-driven pumps in various industries such as oil and gas, manufacturing, chemical, etc., their continuous monitoring and implementing effective maintenance methods is of crucial importance. Periodic inspections and intermittent vibration data collection using accelerometers is among the most common methods. Electrical signature analysis is an alternative approach that only uses electrical measurements for the purpose of fault detection. Despite the unique advantages of this method, such as its non-intrusiveness and possibility of continuous monitoring of the equipment, there have been limited studies on its underlying theory with majority of the proposed ESA-based methods taking data-driven approach towards condition monitoring problem. Data-driven methods rely on the experimental data collected from the equipment to train the statistical models. This imposes a serious limitation on the application of electrical signature analysis and makes the generalization harder. In this paper the electromechanical coupling in a motor-driven centrifugal pump is studied in order to demonstrate the effects of different operating conditions of pump on motor electrical signals. Lumped parameter approach is employed to derive governing equations of the induction motor and computational fluid dynamics is utilized to analyze the interaction of the centrifugal pump blades and fluid. Such a modeling platform presents a physics-based approach towards electrical signature analysis based condition monitoring. A closed-loop hydraulic test rig is built to compare and verify the simulation results.https://ajme.aut.ac.ir/article_5113_2406a0a94c80406914ff2f6c9fdd67d5.pdf