International Journal of Natural and Engineering Sciences

Optimization of the effective width of the foundation of a homogeneous earth dam under earthquake using the IWO algorithm

2024-02-08T08:47:49+03:00

The stability of the earthen dam during an earthquake is important because of the need for safety for the people of that area. Dynamic two-dimensional finite element analysis was performed on a homogeneous earthen dam of Narmab located 5 km south of Minodasht city in Golestan province in Iran. In this study, the effect of theManjil earthquake on the structure of the earthen dam with the water stored in the reservoir has been investigated. In this research, the foundation is assumed to be flexible and not rigid, so the effective width of the foundation in dynamic analysis needs to be considered. The purpose of this research is to determine optimal foundation flank according to the height of the earth dam, which is modeled based on logical assumptions in PLAXIS software. The invasive weed optimization (IWO) algorithm has been used to obtain the effective width of the foundation in the homogeneous earth dam. The result of the algorithm method calculations gives the optimal value of the foundation analysis flanks in terms of dam height equal to 1.81.

Surge control in centrifugal compressor using dynamic controllers

2024-04-26T23:58:25+03:00

Compressors are of particular importance due to their widespread use in various industries for compression and gas transfer. The centrifugal compressor increases the gas pressure and temperature by increasing the kinetic energy using rotating blades. Controlling the compressor's surge phenomenon is very important because it happens very quickly and will cause damage to the compressor, electric motor drive, and the production process. This phenomenon is defined as an instability during compressor workflow and usually occurs in centrifugal compressors. Controlling the surge phenomenon is causing of the expansion the operational range of the compressor operation. In this paper, the third-order Moore–Greitzer’s dynamic model and the active control method are presented based on the back stepping and dynamic surface for controlling the surge phenomenon. The simulation results show that the controllers designed in both ways have the ability to control the compressor in the surge mode. Among the prominent innovations of the article, we can point out a structure for evaluating the back-stage controller in the case of constant increase in the centrifugal compressor and the dynamic level controller in the case of the constant increase in the centrifugal compressor. In Dynamic surface control system indicate that the scaled annulus-averaged flow is stable in 1 s and high accuracy is maintained.

Experimental investigation of the effect of inrush current created by LED drivers on switching elements

2024-04-27T00:00:47+03:00

The demand for lighting technology is increasing rapidly with the increasing population and the advancement of industrialization. Significant developments are taking place in the field of lighting to meet this demand. LED lighting technology, which is the most current of these developments, is preferred to a high degree as it is more efficient, long-lasting, and advantages compared to conventional lighting technologies. However, this technology is still in its development stage and problems may be encountered that need to be solved. In this study, the problems that caused by inrush current and damage to the switch contacts of LED armatures using different protection classes as a result of multiple switching were observed with switching elements complying with IEC 60669-1 standards. The damage on these two switching elements was tested by connecting them with 69 LED armatures of 12A-36W and starting-stopping 10000 times, 40 times per minute. As a result of the test, corrosion/damage that could cause major fires was observed in the LED switching elements and pictures were taken with the help of Scanning Electron Microscope (SEM). The study shows the importance of creating a special international material standard for LED switching systems and ensuring that manufacturers comply with this standard.

Modeling and position control of the inverted pendulum system

2024-04-29T15:52:39+03:00

It is difficult to find the unknown/unmeasurable parameters of in system and the control parameters of the system by experimenting on the real system. The aim of this study is to first find the unknown parameters of the system by creating a mathematical model of the system in a simulation environment, and then to obtain the PID control parameters in the simulation environment with the found parameters. Thus, to see the conformity of the control of the real system to the mathematical model and to show that the unknown parameters can be easily found through simulation. In this study, the position control of the inverted pendulum system, which is one of the control system examples, was carried out to maintain balance. For position control, a mathematical model of the system was first created, then a simulation model was created and experiments were conducted. Experiments were then conducted on a real system using the parameters obtained from the system simulation model. In this study, the car to which the pendulum was connected was controlled to maintain the inverted pendulum system in balance. In the system, a servo motor is used to move the car. The balance position is controlled by moving the car along the horizontal axis. An encoder with a full revolution of 4096 pulses was used to obtain the balance position information of the inverted pendulum. The sensitivity of the encoder used is approximately 11.37 pulses per degree. The experimental setup of the system was created by connecting the rod used as an inverted pendulum to the Encoder. The experimental setup was controlled with a program written in PLC (programmable logic controller). The servo motor that moves the car to ensure that the inverted pendulum remains in balance is controlled by the driver. The servo motor driver was driven by a control signal with ±10 volts sent from the PLC. The servo motor driver is programed to run at ±1000 rpm in response to this control signal. The unmeasurable parameters of the system were experimentally determined. For this purpose, the parameters in the mathematical model were obtained by swarm optimization (PSO) using the measurement values obtained by operating the experimental setup as a simple pendulum. A simulation model of the system was created using the parameters obtained with PSO and the mathematical model. PID (Proportional Integral Derivative) controller was used in the simulation model. The PID parameters required to control the system were obtained using particle swarm optimization in the simulation model. The PID parameters obtained using PSO were used as the parameters of the PID controller in the real experimental system. It was observed that the results obtained in the simulation system and those obtained in the real system overlapped, and the design of the simulation model in this study was successful.

Comparison of the modelling techniques of dynamical systems using momentum and energy principles

2024-05-27T16:34:40+03:00

In undergraduate courses such as engineering mechanics and modelling and simulation, students mostly use Newton’s second law to derive equations of motion in dynamics problems. However, it might be easier and faster in some dynamics problems to use Lagrange’s equation instead of Newton’s second law. To analyze the reason of this situation we will compare the general features of each type of these methods from different aspects. Then we will apply both to some examples and indicate the differences and levels of difficulty accompanying the application of each technique. Three examples from mechanical systems and one example from electrical systems are presented here to show the basic differences between Newton’s second law of motion and Lagrange’s equation. Three examples include a system with a single degree of freedom (translational), two degrees of freedom and multiple degrees of freedom in translation and rotation. For electrical systems, a two degrees of freedom circuit with dual portions is explained using Lagrange’s equation and Kirchhoff law. The advantages and disadvantages of each approach and how the principal concepts in system dynamics are explained to the students are also highlighted.