Rotating machinery is a critical component in mechanical systems, widely used across industrial applications. Due to time-varying speed conditions and complex operating environments, it is highly prone to various failures. Without timely diagnosis and maintenance, such failures can lead to significant performance degradation or catastrophic outcomes. To address the challenges posed by non-stationary operating conditions and vibration signals, researchers have developed diverse fault diagnosis methods, including advanced non-stationary signal processing techniques and data-driven approaches. Among these, generalized demodulation (GD) has demonstrated particular effectiveness in extracting fault-related features from complex signals. This paper provides a comprehensive review of GD-based fault diagnosis methods for rotating machinery. It revisits the fundamental concepts and theoretical basis of GD, analyzes the limitations of traditional approaches, and systematically compares GD with other widely used methods. Furthermore, existing GD-based techniques are categorized into speed-dependent and speed-independent methods based on their reliance on rotational speed, with representative studies and applications discussed. Finally, future research directions and current challenges in GD-based diagnosis are outlined, offering valuable insights for researchers and practitioners in the field.

Planetary gear systems in industrial equipment, characterized by highly integrated structures, non-stationary operating conditions, and heavy-load characteristics, result in significant attenuation of fault-related vibration features, severely limiting the effectiveness of fault diagnosis. Traditional studies often use periodic modulation terms, such as the Hanning window function, to approximate the spatiotemporal distribution characteristics of meshing forces. Although these methods can effectively extract global vibration features of healthy gears (such as meshing frequency and its harmonics), they have significant limitations and are unable to analyze the nonlinear diffusion process of fault impacts through complex paths, resulting in distortion in the phase delay and amplitude attenuation patterns of fault impacts. To address these issues, this study investigates the vibration transmission characteristics of a planetary gearbox through rigid-flexible coupling simulation analysis, focusing on the transmission delay effects of impact responses to the vibration sensors at different housing locations. The study qualitatively clarifies the intrinsic relationship between transmission delay characteristics of the gear-sensor spatial relationship, providing a theoretical foundation for accurate analysis of vibration signals in planetary gear sets. The research highlights the significant spatiotemporal characteristics of the vibration responses when the fault collisions occur at different locations during the rotation and revolution of planet gears.

Resonance occurs when the operating frequency of a system aligns with its natural frequency, resulting in amplified vibration amplitudes. To prevent potential damage and ensure optimal performance of a compressor's base frame at Souq Al-Khamis Cement Factory, researchers found the resonance in has been occurred when both the natural frequencies and rotating frequency were overlapped. Resonant Vibration in the base frames arises when the rotating vibration frequency aligns with the frame’s natural modes that leads to structural instability, fault unplanned shutdowns and production losses. This study analyzes resonant vibration in a cement factory compressor base frame and proposes a redesign using finite element methods to mitigate this issue. Four distinct modifications were made to the base frame on its shape, weight and boundary conditions: the first introduces fixed points to enhance rigidity, the second adds supports for increased stability, the third incorporates elements to improve durability, and the fourth enhances the thickness of the compressor. The results indicate that the redesigned configuration most effectively mitigates resonance and improves the system's natural frequency response.

This study highlights the simulation of a hypothetical fracture in the largest beam tube connected to the core of the Tajoura Nuclear Research Centre's (TNRC) reactor with low enrichment uranium, which produces a maximum thermal power equal to 9.7MW. This study was conducted for the purpose of evaluating the safety of the reactor core when the fracture occurs. The reactor core is cooled in normal operation by downward pumping of coolant (light water) and forced convection, while the reactor core is cooled by natural convection when the cooling pumps stop and after the emergency tank is filled to extract the decay heat. As a result of the temperature difference between the water in the reactor core and the reactor pool, and as a result of the density difference, a reverse flow of coolant occurs in the upward direction. When a break occurs in one of the beam tubes, the Loss of Coolant Accident (LOCA) is started. Consequently, the water level will decrease, and when it reaches 7.4 meters, the cooling pumps will coast down, and thus the SCRAM takes place at the reactor. Because the beam tubes are located in the middle of the reactor core, the water level in the reactor pool will continue to decrease until the denudation of the core takes place when the reactor core is denudated and exposed to air. In this case, the reactor is cooled by two means of heat transfer: natural convection and radiation. Radiation takes place at high temperature differences, in this case, most of heat transfer occurs by natural convection. The MATLAB program was used in this study to perform hydraulic calculations over time in the hottest cell in the reactor core. The results showed that the surface temperatures of the clad exceed the maximum temperature allowed for the surface of the clad (102°C). The temperatures obtained in the surface clad (Aluminum) were compared with the melting temperature, which is 660°C, and it was found that at time 260 sec the clad surface temperature exceeds the melting point. Therefore, it was noticed that when the reactor core is exposed to the air, there is no ability to remove the decay heat by natural convection nor radiation. Thus, temperatures will rise, which will lead to fuel deterioration. To avoid this, it is better to operate the reactor at lower powers thus the decay heat becomes less. In addition, closing the shutters of the beam tubes when the breakage occurs to reduce the amount of leakage and loss of the coolant.

This study is about conducting an economic comparison for establishing small and modular or large reactors in Libya, as analysts and decision makers often want to obtain estimates of the expected cost. There is a national project to establish the first nuclear station in Libya. The aim of this project is to study 19 infrastructure issues according to the International Atomic Energy Agency's Milestone Approach for any newcomer country that embarks on acquiring a nuclear station. One of these important elements of the study is the economic feasibility study of the project. For this, the IAEA INPRO NES simulator tool was used to make this comparison. During this study, the cost of a reactor unit with a capacity equal to 1085 megawatts was compared with approximately 4 equivalent units of the same capacity with small and modular reactors with a capacity of up to 300 megawatts -119921- per unit. These values were chosen to economically compare between a large reactor and four small units for the same total capacity of 1085 megawatts. From the results obtained, it was found that the estimated cost of 4 small and modular reactor units is $67.69 mill per kilowatt-hour, while the estimated cost of the LWR unit is $55.37 mill per kilowatt-hour, which means that establishing 4 SMRs units with a capacity of 300 megawatts per unit is more expensive than establishing a unit of a large 1085 MW reactor. A sensitivity analysis is applied for different discount rates, overnight construction costs, construction time to assess the levelized unit energy cost where the impact of the discount rate is obvious. There is a kind of trade-off between cost and the strength of the electrical network in Libya, as the electrical network is currently weak. It is possible to move forward with small and modular reactors or improve the electrical network to establish a nuclear station with large reactors.

This paper investigates the resonance phenomenon and modal characteristics of a screw air compressor base frame in the cement manufacturing industry. Numerical analysis and data comparison techniques were used to identify and analyze the resonance issue in a specific compressor at Souq Al-Khamis Cement Factory. The research begins by studying the natural frequencies and mode shapes of the compressor base frame through Finite Element Method (FEM) using the ANSYS Workbench. Practical measurements are conducted using the PHYPHOX App Vibration Analyzer to obtain vibration data from the compressor. The findings of this study contribute to understanding the resonance phenomenon in screw air compressors and provide valuable insights for improving the design and maintenance of compressor base frames in the cement manufacturing industry. By identifying the relationship between excitation frequencies and natural frequencies, measures can be taken to mitigate resonance-related vibration problems and ensure the reliable operation of cement production equipment.

Blades are the very important components of wind turbines in order to convert wind energy to mechanical or electrical energy. Therefore, the aerodynamic forces acting on the horizontal wind turbine blades have an important role in their performance. The objective of this paper is to investigate the aerodynamic characteristics and power generation properties for a NREL PHASE VI wind turbine blade. For this purpose, an analysis procedure based on the Blade Element Method (BEM) is demonstrated for a horizontal-axis wind turbine model (HAWT), and the methodology approach is discussed in detail throughout this paper. In this study, a Math Lab code has been developed for analyzing a model of Horizontal-Axis Wind Turbine (HAWT) in order to display aerodynamic behaviour on the blade. The NACA S809 airfoil was selected for the analysis of the wind turbine blade, where the tip and root losses proposed by Prandtl are also executed. The calculated results are validated using Q-Blade commercial software at rated wind speed of 10 m/s and show that the BEM is a good method of aerodynamic investigation of a HAWT blade

Abstract

Blades are the very important components of wind turbines in order to convert wind energy to mechanical or

electrical energy. Therefore, the aerodynamic forces acting on the horizontal wind turbine blades have an important role in

their performance. The objective of this paper is to investigate the aerodynamic characteristics and power generation

properties for a NREL PHASE VI wind turbine blade. For this purpose, an analysis procedure based on the Blade Element

Method (BEM) is demonstrated for a horizontal-axis wind turbine model (HAWT), and the methodology approach is discussed

in detail throughout this paper. In this study, a Math Lab code has been developed for analyzing a model of Horizontal-Axis

Wind Turbine (HAWT) in order to display aerodynamic behaviour on the blade. The NACA S809 airfoil was selected for the

analysis of the wind turbine blade, where the tip and root losses proposed by Prandtl are also executed. The calculated results

are validated using Q-Blade commercial software at rated wind speed of 10 m/s and show that the BEM is a good method of

aerodynamic investigation of a HAWT blade

Abstract

This project investigated the stresses developed in a thick-walled cylinder for rocket motor case

under internal pressure. Stress analysis used the finite element method with ANSYS software for

rocket motor case selection. This study focus on structural elastic analysis of thick-walled pressure

vessels since it is a common design practice to aim at maintaining the induced stresses within the

elastic region. However, pressure vessels operate under complex environments such as high

pressure which may lead to gross plastic deformation and subsequent failure. In process, the

pressure vessel is pressurized beyond the yield point. As a result, the conventional elastic analysis

will not be applicable at internal pressures above the yield point. Therefore, it is important to

examine the structural integrity of a thick-walled pressure vessel in both elastic and plastic state

of the material.

In this study, FE static structural analysis of a presumably untracked thick-walled solid rocket

motor case has been presented, where stress distribution within the motor case wall and the

resulting material deformation were investigated using ANSYS 19.2. Motor case has been designed

with uniform model of the same internal and external diameter, and motor case with diameter

change at both sides is modeled to investigate the effect of the diameter change or shape

discontinuity on the resulting of stresses and deformation using ANSYS program by applying

internal pressure varying from 50 Bars to 350 Bar. Von Mises yield criteria were used by ANSYS

program and calculated Von Mises stresses were compared; the results are close for elastic

analysis. The results show that the Von Mises stresses was high for discontinues shape of motor

case compared by the uniform motor case (constant thickness).

It has been noted the wide spread of the use of composite materials due to their specific strength that made them the best alternative to many other materials,However, the high cost of synthetic fibers represents an obstacle to the use of composite materials in most applications. Therefore, research has tended to test natural fibers, which are the ideal solution for using composite materials in many industries such as furniture, flooring, decoration, and others. This paper concerned with the study of natural composite materials made of Libyan almond shells. Three different sizes of ground almond shells were studied: large size in the form of grains, medium size, and the small size (powder form). These crushed peels were mixed with the resinous polyester resin in four proportions: ratio of 80: 20, 60: 40, 40: 60, and 20: 80. Three basic tests were conducted to investigate the mechanical properties of the samplesIt has been noted the wide spread of the use of composite materials due to their specific strength that made them the best alternative to many other materials, However, the high cost of synthetic fibers represents an obstacle to the use of composite materials in most applications. Therefore, research has tended to test natural fibers, which are the ideal solution for using composite materials in many industries such as furniture, flooring, decoration, and others. This paper concerned with the study of natural composite materials made of Libyan almond shells. Three different sizes of ground almond shells were studied: large size in the form of grains, medium size, and the small size (powder form). These crushed peels were mixed with the resinous polyester resin in four proportions: ratio of 80:20, 60:40, 40:60, and 20:80. Three basic tests were conducted to investigate the mechanical properties of the samples: impact test, tensile test, and flexural test. The results showed that samples made of almond peels in a powder form exhibits the best results among all other kind of specimens for three mentioned tests of mechanical properties.