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The present study investigates vibrational behavior of a porous conical hollow rotor. Inner and outer rotor surface, sensor, and actuator strips made of piezoceramic are modeled and positioned, which are symmetrically distributed in the circumferential direction. Kinetic and potential energies were computed considering the effects of Coriolis and centrifugal force. Modeling of the system has been carried out assuming classical theory and using Lagrange approach for simple-supported boundary conditions. Also, the relations of piezoceramic and three types of porosity attend in equilibrium equations. The discretization of kinetic and potential energies using displacement field which is defined as double mixed series based on independent mode shape and time function leads to obtaining the equations in form of ordinary differential. To calculate the natural frequencies, the equations were converted to a special form of state space model. The correctness of the study is examined by comparing it with similar study results. The most consequential parameters affecting the forward and backward natural frequency, such as type and porosity coefficient, size, number, and thickness of piezoceramic, and the rotor angular velocity, are researched. The results demonstrate that the effect of porosity coefficient in various longitudinal modes on natural frequency is different. [ABSTRACT FROM AUTHOR]

This investigation analyzes the effects of internal static fluid on the free vibrational behavior of joined shells made of carbon nanotube (CNT) fiber‐reinforced composite. Various types of functionally graded CNTs composite with temperature dependence are considered. Classic shell theory and Love's assumptions combined with Hamilton's principle are used to obtain motion equations. Bernoulli equation, velocity potential, and impermeability condition are employed to the coupling effects of fluid pressure with motion equations of shells. Continuity conditions in the joint point of conical and cylindrical sections are supposed to couple equations of two parts. The generalized differential quadrature (GDQ) method is employed to solve equations for various boundary conditions. Experimental modal tests on a sample made by the 3-D printer and prior others' research are used to validate the accuracy of results. Consequently, parametric studies are expressed, such as longitudinal and circumferential mode numbers, semi-vertex angle, distributions of CNTs, CNTs fraction volumes, fluid density, shell thickness, and operating temperature. According to the results, although fluid decreases the frequency generally, the process of changing frequency in terms of other parameters is similar. [ABSTRACT FROM AUTHOR]

This research analyzes the influence of temperature changes on the vibration of single-walled carbon nanotubes (SW-CNTs) composite joined conical-cylindrical shells. The governing dynamic equations of temperature-dependent CNTs with initial thermomechanical stresses are established using the Love shell assumptions and classical shell theory. The initial thermomechanical stresses are derived from the linear membrane approach method. Two possibilities are assumed for the calculation of temperature change: a uniform temperature distribution and steady-state heat transfer by conduction through the thickness of the shell. The initial thermomechanical stresses are determined using the linear membrane approach. The generalized differential quadrature (GDQ) method is used to solve the equations after combining it with continuity conditions between the conical part and the cylindrical part and various boundary conditions. After validating the natural frequency and the different types of temperature distribution with the studies of other researchers, the effects of semi vortex of the cone, the volume fraction, and the type of distribution on the temperature rise are given as the results. The type of temperature distribution has the greatest influence among the parameters. [ABSTRACT FROM AUTHOR]

In this research, a new Z-source inverter inspired by the quasi-inductor-switched Z-source inverter is presented. The new inverter has an acceptable boost factor, and gain voltage compared to the similar Z-source inverter. Also, in this new topology, the capacitors’ voltage stress has been decreased compared to similar inverters. In this converter, a capacitor is replaced with the side diodes of the quasi-Z-source inverter. The input current in this inverter is continuous and it is a low figure that at the moment of switching off about 54 A (V in = 120 V). The high inrush current damages the converter components. The operation of this inverter has been checked in different modes and the voltage and current equations of all elements have been calculated. The new converter can be extended to n-cascade, and it makes to achieve a higher boost factor with a low-duty cycle. The ingredients used in the new topology are fewer than those of the switched-inductor Z-source inverter. The analysis and extraction of all voltage stress such as capacitors, diodes, switches, all currents such as inductors, dc-link average, inrush current, voltage gain and boost factor of the new topology have been done and compared with other structures. The DC-link voltage (Vi ) is 148 V with an input voltage of 120, so the boost factor is 1.43. [ABSTRACT FROM AUTHOR]