Journal of Engineering Research

OPTIMIZING GRID STABILITY: POWER SYSTEM STABILIZER TUNING WITH GENETIC ALGORITHMS

Nouri Khalifa — 2024-11-18

ABSTRACT

Ensuring the stability of an electrical power system is paramount for its reliable and efficient operation. This paper focuses on the crucial task of tuning Power System Stabilizer (PSS) parameters for a generator within the power system. The primary objective is to formulate this tuning process as an optimization problem, leveraging the capabilities of Genetic Algorithms (GA) as the chosen optimization method. By presenting the paper as an optimization problem, the study aims to demonstrate the efficacy of GA in selecting optimal parameters for the power system stabilizer. The focus is on dampening oscillations in the power line, particularly emphasizing its effectiveness under fault conditions. Through extensive simulations, the results underscore the ability of Genetic Algorithms to serve as a robust optimization method, effectively choosing parameters that enhance the power system stabilizer's performance. The findings contribute valuable insights into utilizing GA for optimizing PSS parameters, showcasing its potential to improve grid stability, especially in the face of oscillations and fault scenarios.

EFFECTING BELIEFS OF THE PLACE ON ANCIENT YEMENI ARCHITECTURE IN THE PERIOD BEFORE ISLAM

Ahmed AL-Nehmi — 2024-11-18

ABSTRACT

The study tries to highlight ancient Yemen's civilization, especially in the architectural field, to bring it to light. The problem of study is the lack of understanding of the old Yemeni architecture and its effects, especially the impact of the sacred place on architecture. It focuses on determining the relationship between the beliefs of Yemeni society and the place affecting the formulation of architecture. The study aims to interpret the architectural place by using a general framework for the sacred place of literature reviews and comparison among themselves, and then apply it to the architecture. The study concluded that the concept of sacred place was an idea in which all the ancient near east civilizations had taken it. It was also concluded that the old architecture of Yemen reflects the concept of the sacred place and its elements.

A SOLVER-TOPSIS TECHNIQUE FOR MULTI-OBJECTIVE OPTIMIZATION OF INNOVATIVE MULTI-STAGE VCR SYSTEMS BY USING MICROSOFT EXCEL

Mohamed El-Awad — 2024-11-18

ABSTRACT

This paper describes a method for multi-objective optimisation analyses of multi-stage vapour-compression refrigeration (VCR) systems by utilising the single-objective solver of Microsoft Excel and the TOPSIS decision-making method. The paper illustrates the Solver-TOPSIS method by analysing an innovative two-stage VCR system that adds a heat-recovery intercooler to the conventional system after the first-stage compressor. The Excel-aided model developed for the system calculates its coefficient of performance (COP), exergetic efficiency, total cost rate, and total equivalent warming impact (TEWI). Four design parameters are treated as variables which are the evaporator and condenser temperatures, the isentropic efficiency of the compressor, and the flow rate of the cooling water. Comparing the values of the four performance indicators as optimised by the proposed method with those optimised by the MIDACO solver shows that the method yields higher values of the system’s COP and exergetic efficiency and lower TEWI at the expense of slightly increasing the total cost rate. The total rate of exergy destruction in the system optimised by excel method is also lower than in the one optimised by MIDACO.

UTILIZING EXCEL SOLVER FOR COMPLEX PIPE NETWORK ANALYSIS AND DEVELOPMENT OF AN EDUCATIONAL TOOL

Nasreddin Al-Zalitani — 2024-11-18

ABSTRACT

This study aims to enhance the analysis methodology for complex pipe networks. An approach was proposed involving the formulation of continuity and head loss equations adapted through the application of both Excel Solver and the Hardy Cross methods. Furthermore, using Solver add-in with the aid of Visual Basic for Application (VBA) helped to extend the study beyond theoretical analysis where an educational tool has been developed, thereby providing a practical resource for further exploration and understanding of such analyzing methods. As the optimization has been conducted and the flow rates values determined, it was observed that there is a significant reduction in the time required for iterative approach while the calculation accuracy was not affected. On the other hand, the developed educational tool has easily and effectively explored the analyzing of simple and complicated piping systems.

INVESTIGATING THE INFLUENCE OF CERTAIN PARAMETERS ON THE DYNAMIC CHARACTERISTICS OF A COMPOSITE WING STRUCTURE

Marwa . Agela — 2024-11-18

ABSTRACT

This paper discusses the effect of some parameters such as fibre orientations, laminate stacking sequence, aspect ratios and stiffness of the rectangular composite wing box models for the free vibration analysis on two wing configurations, the first one producing a material coupling, bend-twist stiffness and the other without material coupling, bend-twist stiffness vanishes. A computer program within MATLAB language is developed to deal with the calculation of the bending, torsion and bend-twist stiffnesses ( , , and ) for the two wing configurations in order to understand their behaviour. Free vibration analysis is also carried out using the finite element program MSC/PATRAN and MSC/NASTRAN v2004 for the same wing configurations. The maximum bending stiffness, torsion stiffness and bend-twist coupling stiffness are found at 0^o, ±30^o and ±20^o fibre orientations respectively for the CAS and with zero coupling for the CUS models. It was found that wing stiffnesses are universally proportional with the aspect ratios. A similar variations of the material stiffnesses, eigenvalues and associated eigenvectors versus fibre angle are observed. The effect of aspect ratio on the fundamental bending frequency is almost negligible compared with the torsional frequency, whereas is more pronounced on the torsional frequency compared with bending frequency.

SPECTRAL ANALYSIS OF DIFFUSION FLAME DYNAMICS WITH FUEL EXCITED AND ITS INTERACTION WITH AN ACOUSTICALLY RIJKE TUBE

Salem Farhat — 2024-11-18

ABSTRACT

The instability of combustion processes in heat engines, particularly those with continuous fuel injection such as gas turbines and jet engines, poses significant challenges impacting efficiency, fuel consumption, and engine life. A critical factor contributing to this instability is the interaction between fluctuating heat release from combustion and acoustic pressure fluctuations within the combustion chamber. Rayleigh criteria have been pivotal to understanding this instability, particularly in settings like the Rijke tube, where acoustic excitation plays a crucial role. In recent experimental studies, the dynamics of diffusion flames within a vertical Rijke tube were investigated extensively. In this paper, the Rijke tube is acoustically excited at first three harmonics mode of 74 Hz, 222 Hz and 370 Hz, and fuel is excited with frequencies from 30 Hz to 300 Hz. Measurements included acoustic pressure via microphone system and flame chemiluminescence emissions via light cell system have been analyzed. Notably, at a fuel excitation frequency of 90 Hz, significant flame instability was observed, influencing both flame appearance and spectral characteristics. Under excitation, the initially laminar flame transitioned to turbulence, characterized by a change in flame color to blue and a distinctive V-shaped flame structure with rotational behavior. Increasing excitation further led to flame lift-off and extinction, akin to scenarios with increased fuel flow rates. Spectral analysis revealed a transition from a dominant frequency of 13 Hz (typical for laminar flame) to higher frequencies as instability progressed towards flame blowout. Moreover, experiments within the Rijke tube demonstrated strong interactions between fuel excitation and tube harmonics, notably at the first harmonic frequency where anti-node pressure fluctuations were most pronounced. This interaction significantly affected flame stability, evident in RMS values peaks of chemiluminescence emissions, while decays indicated instability or extinguishment. Acoustic pressure fluctuations, particularly at the first harmonic frequency, exerted a significant destabilizing effect, whereas lesser effects were noted at higher harmonics, where acoustic velocity fluctuations are high. Cross-correlation analysis between acoustic pressure and flame chemiluminescence emissions highlighted clear distinctions between stable and unstable conditions. These findings underscore the complexity of combustion instability and its sensitivity to acoustic conditions and fuel excitation frequencies. Such insights are crucial for developing effective stability control systems, whether active or passive, aimed at enhancing engine performance and reliability in diverse operational conditions.

SPATIAL ANALYSIS OF TRAFFIC ACCIDENTS USING GIS

Ali Bin Saeid — 2024-11-18

ABSTRACT

The interactive digital map provided by GIS is a means that enables specialists in many fields to conduct various analyses, starting with the creation of a geographical database on the basis of which the necessary analysis operations can be performed. Traffic accident data has been collected from paper records in the archives of the Evidence Collection Section at the Traffic Affairs Office - Tripoli Security Directorate, and the results of the density analysis "Cornell Density" showed that traffic accidents were distributed more in the downtown neighbourhoods than in the suburbs. On the other hand, the severity was higher in the suburbs than in the city centre, and the first cause of traffic accidents in the entire road network was the speed of vehicles which is excess of the permitted vehicles one.