Estimation of mean and median frequency from synthetic sEMG signals: Effects of different spectral shapes and noise on estimation methods

2022 ◽  
Vol 73 ◽  
pp. 103420
Author(s):  
Giovanni Corvini ◽  
Carmen D'Anna ◽  
Silvia Conforto
Keyword(s):  
Estimation Methods ◽  
Median Frequency ◽  
Semg Signals ◽  
Spectral Shapes

Evaluation of Lower Limb Muscles Fatigue and Force during Running 400-Meters Using Learning Machine

2019 ◽  
Vol 43 ◽  
pp. 39-53
Author(s):  
Hayder A. Yousif ◽  
Abdul Rahim Norasmadi ◽  
Ahmad Faizal Bin Salleh ◽  
Ammar Zakaria
Keyword(s):  
Research Work ◽  
Gluteus Maximus ◽  
Median Frequency ◽  
Bipolar Electrodes ◽  
Lower Limb Muscles ◽  
Full Speed ◽  
Linear Slope ◽  
Learning Machine ◽  
The Right ◽  
Semg Signals

The main goal of this research work is to study and evaluate the muscles force and fatigue of Gastrocnemius Medialis (GMS), Gluteus Maximus (GM), and Gastrocnemius Lateralis (GL) during running for 400-meters based on surface Electromyography (sEMG) signals. The sEMG signals of the selected muscles from the right leg have been collected by using bipolar electrodes from 15 subjects during the run on the tartan athletic track with two pacing strategies. The first strategy: 1st 200-meters running 87% - 94% of full speed and last 200-meters sprinting (full speed). The second strategy: 1st 300-meters running 87% - 94% of sprinting and last 100-meters sprinting. The rate of fatigue has been calculated by using Root Mean Square (RMS) and Median Frequency (MDF) features. Then, the slopes of linear regression were calculated from both RMS and MDF at each 100-meters. The linear slope values represented the rate of fatigue and force. From the results of 1st and 2nd running strategies, the force of GM and GL muscles increased during the 4th 100-meters of the 1st strategy and decreased with GM and GMS muscles during the 4th 100-meters of the 2nd strategy. The less index fatigues were during the 1st strategy for most selected muscles. Finally, it can be concluded the running with the 1st strategy get less fatigues and the force of most selected muscles increased compared with the 2nd strategy based on the results of time and frequency domain features (RMS and MDF).

Quantifying uncertainties in attenuation estimation at methane-hydrate-bearing zones using sonic waveform logs

Geophysics ◽  
2013 ◽  
Vol 78 (5) ◽  
pp. D339-D353 ◽  
Author(s):  
Hiroyuki Suzuki ◽  
Jun Matsushima
Keyword(s):  
Frequency Shift ◽  
Methane Hydrate ◽  
Seismic Attenuation ◽  
Estimation Methods ◽  
Ratio Method ◽  
Median Frequency ◽  
Waveform Data ◽  
Shift Method ◽  
Sonic Logging ◽  
Attenuation Estimation

Application of seismic attenuation estimation using sonic waveform data is limited because the estimation methods have not yet been fully developed. Although the median frequency shift method is considered to be effective and robust compared to the conventional spectral ratio method, we demonstrated that the median frequency shift methods strongly depend on reference data under lower signal-to-noise ratios. We modified an existing median frequency shift method not to depend on arbitrarily choosing a reference value and to quantify the uncertainties in attenuation estimation. Furthermore, we implied the optimum selection of receiver pairs used for more stable attenuation analysis. Our numerical experiments supported the advantage of the proposed method. Although our main findings by applying the proposed methods in methane hydrate-bearing sediments are almost consistent with past field sonic logging measurements, we find some differences in the magnitude of attenuation values compared to existing sonic attenuation measurements and discuss various possible factors. We believe that more stable and reliable attenuation results can lead to clarifying various factors affecting attenuation estimation, such as the effect of scattering, near-field effects, and source-coupling effects. Furthermore, we emphasized the importance of scattering effect caused by the heterogeneity of the formation and demonstrated the limitation of characterizing the 1D heterogeneity using the sonic logging data spatially sampled at 0.15 m to adequately estimate the effect of scattering attenuation.

ANALYSIS OF SURFACE EMG SIGNALS UNDER FATIGUE AND NON-FATIGUE CONDITIONS USING B-DISTRIBUTION BASED QUADRATIC TIME FREQUENCY DISTRIBUTION

2015 ◽  
Vol 15 (02) ◽  
pp. 1540028 ◽  
Author(s):  
P. A. KARTHICK ◽  
G. VENUGOPAL ◽  
S. RAMAKRISHNAN
Keyword(s):  
Frequency Distribution ◽  
Biceps Brachii ◽  
Surface Emg ◽  
Median Frequency ◽  
Biceps Brachii Muscle ◽  
Spectral Entropy ◽  
Time Frequency ◽  
Neuromuscular Conditions ◽  
Time Frequency Distribution ◽  
Semg Signals

In this paper, an attempt has been made to analyze surface electromyography (sEMG) signals under non-fatigue and fatigue conditions using time-frequency based features. The sEMG signals are recorded from biceps brachii muscle of 50 healthy volunteers under well-defined protocol. The pre-processed signals are divided into six equal epochs. The first and last segments are considered as non-fatigue and fatigue zones respectively. Further, these signals are subjected to B-distribution based quadratic time-frequency distribution (TFD). Time frequency based features such as instantaneous median frequency (IMDF) and instantaneous mean frequency (IMNF) are extracted. The expression of spectral entropy is modified to obtain instantaneous spectral entropy (ISPEn) from the time-frequency spectrum. The results show that all the extracted features are distinct in both conditions. It is also observed that the values of all features are higher in non-fatigue zone compared to fatigue condition. It appears that this method is useful in analysing various neuromuscular conditions using sEMG signals.

Attenuation estimation from sonic logging waveforms combining seismic interferometry and common-midpoint approach

Geophysics ◽  
2018 ◽  
Vol 83 (1) ◽  
pp. WA21-WA35 ◽  
Author(s):  
Jun Matsushima ◽  
Mohammed Y. Ali ◽  
Fateh Bouchaala
Keyword(s):  
Signal To Noise Ratio ◽  
Depth Resolution ◽  
Estimation Methods ◽  
Seismic Interferometry ◽  
Median Frequency ◽  
Trade Off ◽  
Advantages And Disadvantages ◽  
Attenuation Profiles ◽  
Sonic Logging ◽  
Attenuation Estimation

Although attenuation estimation methods using sonic logging waveforms provide the highest resolution among seismic methods and enable us to characterize in great detail the attenuation properties of subsurface rocks, such attenuation estimation methods are not used routinely, indicating that there is still room for improvement. To further improve the performance of an existing modified median frequency shift (MMFS) method, we have developed a new algorithm by combining seismic interferometry (SI) and the common-midpoint (CMP) approach. Redatuming a transmitter position by applying SI can shorten the transmitter-receiver distance, leading not only to higher depth resolution but also to a lower signal-to-noise ratio (S/N) of the attenuation profiles. To compensate for the decrease in the S/N, we used the redundancy of overlapping receivers at each receiver level in a sonic logging measurement using the multireceiver tool; we improved the S/N by stacking the redatumed sonic logging waveforms. Then, based on the CMP approach, we constructed the workflow to estimate attenuation using redatumed sonic logging waveforms. We applied our method to numerical and real sonic logging waveforms to investigate its applicability in comparison with that of the existing MMFS method in terms of depth resolution and S/N. The results of numerical experiments on noisy data and velocity heterogeneity models demonstrate a trade-off relationship between the depth resolution and stability, which can be controlled by selecting transmitter-receiver pairs. Finally, the application of our method to real sonic logging data demonstrates the advantages in terms of resolution and the disadvantages in stability in comparison with the existing MMFS method. Similar to the numerical results, we found a trade-off relationship between such advantages and disadvantages, which can be controlled by selecting transmitter-receiver pairs.

scholarly journals Effective Assessments of a Short-duration Poor Posture on Upper Limb Muscle Fatigue before Physical Exercise

2020 ◽  
Author(s):  
Lei Lu ◽  
Mark Robinson ◽  
Ying Tan ◽  
Kusal Goonewardena ◽  
Xinliang Guo ◽  
...  
Keyword(s):  
Short Duration ◽  
Upper Limb ◽  
Physical Activities ◽  
Median Frequency ◽  
Back Muscles ◽  
Time Frequency ◽  
Short Period ◽  
Frequency Components ◽  
Set Up ◽  
Semg Signals

ABSTRACTA forward head and rounded shoulder posture is a poor posture that is widely seen in everyday life. It is known that sitting in such a poor posture with long hours will bring health issues such as muscle pain. However, it is not known whether sitting in this poor posture for a short period of time will affect human activities. This paper investigates the effects of a shortduration poor posture before some typical physical activities such as push-ups. The experiments are set up as follows. Fourteen male subjects are asked to do push-ups until fatigue with two surface electromyography (sEMG) at the upper limb. Two days later, they are asked to sit in this poor posture for 15 mins with 8 sEMG sensors located at given back muscles. Then they do the push-ups after the short-duration poor posture. The observations from the median frequency of sEMG signals at the upper limb indicate that the short-duration poor posture does affect the fatigue procedure of push-ups. A significant decreasing trend of the performance of push-ups is obtained after sitting in this poor posture. Such effects indicate that some parts of the back muscles indeed get fatigued with only 15 minutes sitting in this poor posture. By further investigating the time-frequency components of sEMG of back muscles, it is observed that the low and middle frequencies of sEMG signals from the infraspinatus muscle of the dominant side are demonstrated to be more prone to fatigue with the poor posture. Although this study focuses only on push-ups, similar experiments can be arranged for other physical exercises as well. This study provides new insights into the effect of a short-duration poor posture before physical activities. These insights can be used to guide athletes to pay attention to postures before physical activities to improve performance and reduce the risk of injury.

The Impact of Missing and Error-Prone Auxiliary Information on Sparse-Matrix Sub-Population Parameter Estimates

Methodology ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 89-99 ◽  
Author(s):  
Leslie Rutkowski ◽  
Yan Zhou
Keyword(s):  
Sparse Matrix ◽  
Small Body ◽  
Auxiliary Information ◽  
Poor Quality ◽  
Quality Data ◽  
Estimation Methods ◽  
Parameter Estimates ◽  
Population Parameter ◽  
Conditioning Model ◽  
The Impact

Abstract. Given a consistent interest in comparing achievement across sub-populations in international assessments such as TIMSS, PIRLS, and PISA, it is critical that sub-population achievement is estimated reliably and with sufficient precision. As such, we systematically examine the limitations to current estimation methods used by these programs. Using a simulation study along with empirical results from the 2007 cycle of TIMSS, we show that a combination of missing and misclassified data in the conditioning model induces biases in sub-population achievement estimates, the magnitude and degree to which can be readily explained by data quality. Importantly, estimated biases in sub-population achievement are limited to the conditioning variable with poor-quality data while other sub-population achievement estimates are unaffected. Findings are generally in line with theory on missing and error-prone covariates. The current research adds to a small body of literature that has noted some of the limitations to sub-population estimation.

Femtocell Selection Scheme for Reducing Unnecessary Handover and Enhancing Downlink QoS in Cognitive Femtocell Networks

2017 ◽  
Author(s):  
Hoang Nhu Dong ◽  
Hoang Nam Nguyen ◽  
Hoang Trong Minh ◽  
Takahiko Saba
Keyword(s):  
Cellular Networks ◽  
Estimation Methods ◽  
Mobility Prediction ◽  
Capacity Estimation ◽  
Femtocell Networks ◽  
Selection Scheme ◽  
Indoor Communications ◽  
Performance Results ◽  
Cognitive Femtocell

Femtocell networks have been proposed for indoor communications as the extension of cellular networks for enhancing coverage performance. Because femtocells have small coverage radius, typically from 15 to 30 meters, a femtocell user (FU) walking at low speed can still make several femtocell-to-femtocell handovers during its connection. When performing a femtocell-to-femtocell handover, femtocell selection used to select the target handover femtocell has to be able not only to reduce unnecessary handovers and but also to support FU’s quality of service (QoS). In the paper, we propose a femtocell selection scheme for femtocell-tofemtocell handover, named Mobility Prediction and Capacity Estimation based scheme (MPCE-based scheme), which has the advantages of the mobility prediction and femtocell’s available capacity estimation methods. Performance results obtained by computer simulation show that the proposed MPCE-based scheme can reduce unnecessary femtocell-tofemtocell handovers, maintain low data delay and improve the throughput of femtocell users. DOI: 10.32913/rd-ict.vol3.no14.536

Biorefinery implementation for recovery debottlenecking at existing pulp mills- Part II: Techno-economic evaluation

TAPPI Journal ◽  
2012 ◽  
Vol 11 (8) ◽  
pp. 17-24 ◽  
Author(s):  
HAKIM GHEZZAZ ◽  
LUC PELLETIER ◽  
PAUL R. STUART
Keyword(s):  
Cost Estimation ◽  
Process Model ◽  
Black Liquor ◽  
Pulp Mill ◽  
Value Added ◽  
Economic Assessment ◽  
Extraction Process ◽  
Estimation Methods ◽  
Precipitation Process

The evaluation and process risk assessment of (a) lignin precipitation from black liquor, and (b) the near-neutral hemicellulose pre-extraction for recovery boiler debottlenecking in an existing pulp mill is presented in Part I of this paper, which was published in the July 2012 issue of TAPPI Journal. In Part II, the economic assessment of the two biorefinery process options is presented and interpreted. A mill process model was developed using WinGEMS software and used for calculating the mass and energy balances. Investment costs, operating costs, and profitability of the two biorefinery options have been calculated using standard cost estimation methods. The results show that the two biorefinery options are profitable for the case study mill and effective at process debottlenecking. The after-tax internal rate of return (IRR) of the lignin precipitation process option was estimated to be 95%, while that of the hemicellulose pre-extraction process option was 28%. Sensitivity analysis showed that the after tax-IRR of the lignin precipitation process remains higher than that of the hemicellulose pre-extraction process option, for all changes in the selected sensitivity parameters. If we consider the after-tax IRR, as well as capital cost, as selection criteria, the results show that for the case study mill, the lignin precipitation process is more promising than the near-neutral hemicellulose pre-extraction process. However, the comparison between the two biorefinery options should include long-term evaluation criteria. The potential of high value-added products that could be produced from lignin in the case of the lignin precipitation process, or from ethanol and acetic acid in the case of the hemicellulose pre-extraction process, should also be considered in the selection of the most promising process option.

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