Discrete Wavelet Transform Analysis of Surface Electromyography for the Objective Assessment of Neck and Shoulder Muscle Fatigue

Objective assessment of neuromuscular fatigue caused by sub-maximal repetitive exertions is essential for the early detection and prevention of risks of neck and shoulder musculoskeletal disorders. In recent years, discrete wavelet transforms (DWT) of surface electromyography (SEMG) has been used to evaluate muscle fatigue, especially during dynamic contractions when the SEMG signal is non-stationary. However, its application to neck muscle fatigue assessment is not well established. Therefore, the purpose of this study was to establish DWT analysis as a suitable method to conduct quantitative assessment of neck muscle fatigue caused by dynamic exertions. Ten human participants performed 40 minutes of fatiguing repetitive arm and neck exertions. SEMG data from the upper trapezius and sternocleidomastoid muscles were recorded. Ten most commonly used orthogonal wavelet functions were used to conduct DWT analysis. A significant increase in the power was observed at lower frequency bands of 6-12Hz, 12-23 Hz, and 23-46 Hz with the onset and development of fatigue for most of the wavelet functions. Among ten wavelet function, a relatively higher power estimation, consistent statistical trend and better power contrast with the onset and development of fatigue was observed for the Rbio3.1 wavelet function. The results of this study will assist Professional Ergonomists to automate the process of localized muscle fatigue estimation, which could have applications related to improving working environment

Evaluation of Concavity Compression Mechanism as a Possible Predictor of Shoulder Muscle Fatigue

This study examined the lived experiences of American Muslim principals who serve in public schools post-9/11 to determine whether global events, political discourse, and the media coverage of Islam and Muslims have affected their leadership and spirituality. The aim of the study was to allow researchers and educators to gain an understanding of the adversities that American Muslims principals have experienced post-9/11 and to determine how to address these adversities, particularly through decisions about educational policy and district leadership. A total of 14 American Muslim school leaders who work in public schools post-9/11 across the United States participated in the study, and a phenomenological methodology was used to direct the data collection and coding. Edelman\u27s political spectacle theory served as the theoretical framework for the research. The findings yielded six themes of political climate, role of the media, inferior and foreign: being seen as the other, unconscious fear, spirituality, and education and communication over spectacle. Further, collective guilt and social responsibility emerged as two additional findings. The research suggests that political spectacle and its effects have a large impact on the lives of American Muslim principals, particularly in regard to their leadership and spirituality

Investigation of Power Performance of a PEM Fuel Cell Using MATLAB Simulation

Fuel cell based power generation systems have gained remarkable interest in this modern age, due to its high conversion efficiency and reliability. Among the different types of fuel cells, PEM fuel cells are achieving more significance due to its fast start up time and low operating temperature. This paper studies the mathematical model of proton exchange membrane of fuel cell (PEMFC) using Matlab/SIMULINK software. The paper consists of the calculation of cell voltage, stack current, ohmic loss, activation loss. This model is used to research the fuel cell behavior and the characteristic of output values at different parameters. The model consists of the cathode gas channel, gas diffuser, catalyst layer, and the membrane. In order to composite shape of the gas diffuser and for its gradient in liquid water content, the gas diffuser is modeled as a series of parallel layers with different porosity. It represents in terms of the physical and thermodynamic parameters of the fuel cell. The curve of polarization is expressed parametrically as a function of the surface over potential. This paper expresses for cathode internal as well as overall effectiveness factors, active fraction of the catalyst layer resistance, catalyst layer, limiting current density, and the slope of the polarization curve

Ultra-narrow and widely tunable Mn^(2+) Emission from Single Nanocrystals of ZnS-CdS alloy

Extensively studied Mn-doped semiconductor nanocrystals have invariably exhibited photoluminescence (PL) over a narrow energy window of width <= 149 meV in the orange-red region and a surprisingly large spectral width (>= 180 meV), contrary to its presumed atomic-like origin. Carrying out emission measurements on individual single nanocrystals and supported by ab initio calculations, we show that Mn PL emission, in fact, can (i) vary over a much wider range (~ 370 meV) covering the deep green-deep red region and (ii) exhibit widths substantially lower (~ 60-75 meV) than reported so far, opening newer application possibilities and requiring a fundamental shift in our perception of the emission from Mn-doped semiconductor nanocrystals.Comment: 5 pages, 5 figure