The effect of the menstrual cycle on physical characteristics (speed, strength, and endurance) in women in Saudi Arabia

The increasing participation of women in sports has raised interest in understanding how the menstrual cycle, specifically estrogen, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH), affects athletic performance. These hormones fluctuate throughout the menstrual cycle, which is divided into the early follicular phase, ovulatory period, and mid-luteal phase, each with distinct hormonal profiles. While estrogen is believed to have an anabolic effect on skeletal muscle and influence substrate metabolism, progesterone may have an antiestrogenic effect, potentially affecting physical performance. However, research on the impact of these hormone fluctuations on performance yields contradictory results. Some studies report improved performance during various menstrual cycle phases, while others find no significant differences. Additionally, the effects of oral contraceptives (OCPs) on muscle strength and function remain unclear. Menopause, characterized by a decline in skeletal muscle mass and bone density, is associated with reduced physical performance in women. More research is needed to understand the effects of estrogen and progesterone fluctuations on physical performance in women, emphasizing the importance of gender-specific research and guidelines for optimizing athletic performance.

Modal Moment Index For Damage Detection In Beam Structures

Health monitoring and damage detection in structures such as airframes are crucial to their safety and performance. Damage-induced changes in natural frequencies, damping ratios and mode shapes can be detected using experimental modal analysis (EMA), which has recently enjoyed intense research for application in structural health monitoring. A main theme of the current research has been to formulate a parameter, calculated using the measured changes in eigenparameters, which exhibits a significant \u27jump\u27 at the damage location and whose value is a direct measure of the severity of the damage. A damage-sensitive parameter thus serves to localize the damage and to assess its severity, and it should likewise minimize the likelihood of false indications or of missing damage. Here, using finite element analysis of the damaged cantilevered beam, we study several existing parameters and introduce a new parameter called the Modal Moment Index (MMI). MMI is shown to jump sharply at the damage site and to have a direct relationship to the damage level. © Springer-Verlag 2000

Multi-cracks identification based on the nonlinear vibration response of beams subjected to moving harmonic load

The aim of this work is to investigate the nonlinear forced vibration of beams containing an arbitrary number of cracks and to perform a multi-crack identification procedure based on the obtained signals. Cracks are assumed to be open and modelled trough rotational springs linking two adjacent sub-beams. Forced vibration analysis is performed by a developed time differential quadrature method. The obtained nonlinear vibration responses are analyzed by Huang Hilbert Transform. The instantaneous frequency is used as damage index tool for cracks detection

Crack identification based on the nonlinear response of plates with variably oriented surface crack.

In order to secure structural and operational safety of structures, it is important to implement a structural health monitoring (SHM) strategy to issue early warnings on damage or deterioration prior to costly repair or even catastrophic collapse. Developing a SHM strategy for structures enables evaluating structural integrity, durability and reliability of the monitored structure. Hence, the main objective of this work is to develop a damage detection procedure based on a plate’s dynamic response and the Hilbert transform. Rectangular plates are considered and assumed to contain a surface crack which is centrally located, with a depth of h0, a length of 2C and inclined with an angle β. Von Karman plate theory is adopted herein, and the crack is modeled through the line spring model given by fracture mechanics. The plate is assumed to behave nonlinearly due to large deformation. The differential quadrature method is used to investigate the linear and nonlinear dynamic behaviors of cracked plates. The influence of crack’s parameters on modal properties is discussed. The eigenfrequencies of cracked plates with respect to crack half length C and orientation β are performed. For crack characterization, Hilbert transform is applied to the obtained linear and nonlinear time responses. It is shown throughout this paper that identified backbones describe changes in crack orientation

Multi-cracks identification based on the nonlinear vibration response of beams subjected to moving harmonic load

The aim of this work is to investigate the nonlinear forced vibration of beams containing an arbitrary number of cracks and to perform a multi-crack identification procedure based on the obtained signals. Cracks are assumed to be open and modelled trough rotational springs linking two adjacent sub-beams. Forced vibration analysis is performed by a developed time differential quadrature method. The obtained nonlinear vibration responses are analyzed by Huang Hilbert Transform. The instantaneous frequency is used as damage index tool for cracks detection

Crack identification based on the nonlinear response of plates with variably oriented surface crack.

In order to secure structural and operational safety of structures, it is important to implement a structural health monitoring (SHM) strategy to issue early warnings on damage or deterioration prior to costly repair or even catastrophic collapse. Developing a SHM strategy for structures enables evaluating structural integrity, durability and reliability of the monitored structure. Hence, the main objective of this work is to develop a damage detection procedure based on a plate’s dynamic response and the Hilbert transform. Rectangular plates are considered and assumed to contain a surface crack which is centrally located, with a depth of h0, a length of 2C and inclined with an angle β. Von Karman plate theory is adopted herein, and the crack is modeled through the line spring model given by fracture mechanics. The plate is assumed to behave nonlinearly due to large deformation. The differential quadrature method is used to investigate the linear and nonlinear dynamic behaviors of cracked plates. The influence of crack’s parameters on modal properties is discussed. The eigenfrequencies of cracked plates with respect to crack half length C and orientation β are performed. For crack characterization, Hilbert transform is applied to the obtained linear and nonlinear time responses. It is shown throughout this paper that identified backbones describe changes in crack orientation

Nonlocal Thermoelasticity Theory for Thermal-Shock Nanobeams with Temperature-Dependent Thermal Conductivity

© 2015 Taylor and Francis Group, LLC. In this work, a model of nonlocal generalized thermoelasticity with one thermal relaxation time is used to consider the vibration behavior of an Euler-Bernoulli (E-B) nanobeam. The thermal conductivity of the nanobeam is assumed to be temperature-dependent. The nonlocality brings in an internal length scale in the formulation and, thus, allows for the interpretation of size effects. The governing partial differential equations are solved in the Laplace transform domain by adopting the state-space approach of modern control theory. The inverse of Laplace transforms are numerically computed using Fourier expansion techniques. The distributions of the lateral vibration, the temperature, the axial displacement and the bending moment of the nanobeam are determined. The effect of thickness and variability of thermal conductivity, as well as the influence of the nonlocal parameter are investigated