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Sample records for surface electromyogram semg

  1. Surface electromyogram signals classification based on bispectrum.

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    Orosco, Eugenio; Lopez, Natalia; Soria, Carlos; di Sciascio, Fernando

    2010-01-01

    This paper bispectrum is used to classify human arm movements and control a robotic arm based on upper limb's surface electromyogram signals (sEMG). We use bispectrum based on third-order cumulant to parameterize sEMG signals and classify elbow flexion and extension, forearm pronation and supination, and rest states by an artificial neural network (ANN). Finally, a robotic manipulator is controlled based on classification and parameters extracted from the signals. All this process is made in real-time using QNX ® operative system.

  2. Application of higher order statistics to surface electromyogram signal classification.

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    Nazarpour, Kianoush; Sharafat, Ahmad R; Firoozabadi, S Mohammad P

    2007-10-01

    We propose a novel approach for surface electromyogram (sEMG) signal classification. This approach utilizes higher order statistics of sEMG signal to classify four primitive motions, i.e., elbow flexion, elbow extension, forearm supination, and forearm pronation. In documented research, the sEMG signal generated during isometric contraction is modeled by a stationary process whose probability density function (pdf) is assumed to be either Gaussian or Laplacian. In this paper, using Negentropy, we demonstrate that the level of non-Gaussianity of sEMG signal recorded in muscular forces below 25% of maximum voluntary contraction (MVC) is significant. Therefore, application of higher order statistics in sEMG signal processing is justified, due to the fact that more useful information can be extracted from the corresponding higher order statistics. An accurate classification is achieved by using the sequential forward selection (SFS) method for reducing of the dimensionality of feature space and the K-nearest neighbor (KNN) classifier. The results indicate that the proposed approach provides higher sEMG correct classification rates as compared to the existing methods.

  3. Computation of fractal features based on the fractal analysis of surface electromyogram to estimate force of contraction of different muscles.

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    Poosapadi Arjunan, Sridhar; Kumar, Dinesh Kant

    2014-01-01

    This research study investigates the fractal properties of surface Electromyogram (sEMG) to estimate the force levels of contraction of three muscles with different cross-sectional areas (CSA): m. quadriceps--vastus lateralis, m. biceps brachii, andm. flexor digitorum superficialis. The fractal features were computed based on the fractal analysis of sEMG, signal recorded while performing sustained muscle contraction at different force levels. A comparison was performed between the fractal features and five other features reported in the literature. Linear regression analysis was carried out to determine the relationship between the force of contraction (20-100%) and features of sEMG. The results from the coefficients of regression r² show that the new fractal feature, maximum fractal length of the signal has highest correlation (range 0.88-0.90) when compared with other features which ranges from 0.34 to 0.74 for the three different muscles. This study suggests that the estimation of various levels of sustained contraction of muscles with varied CSA will provide a better insight into the biomechanics model that involves muscle properties and muscle activation.

  4. Blind source identification from the multichannel surface electromyogram

    International Nuclear Information System (INIS)

    Holobar, A; Farina, D

    2014-01-01

    The spinal circuitries combine the information flow from the supraspinal centers with the afferent input to generate the neural codes that drive the human skeletal muscles. The muscles transform the neural drive they receive from alpha motor neurons into motor unit action potentials (electrical activity) and force. Thus, the output of the spinal cord circuitries can be examined noninvasively by measuring the electrical activity of skeletal muscles at the surface of the skin i.e. the surface electromyogram (EMG). The recorded multi-muscle EMG activity pattern is generated by mixing processes of neural sources that need to be identified from the recorded signals themselves, with minimal or no a priori information available. Recently, multichannel source separation techniques that rely minimally on a priori knowledge of the mixing process have been developed and successfully applied to surface EMG. They act at different scales of information extraction to identify: (a) the activation signals shared by synergistic skeletal muscles, (b) the specific neural activation of individual muscles, separating it from that of nearby muscles i.e. from crosstalk, and (c) the spike trains of the active motor neurons. This review discusses the assumptions made by these methods, the challenges and limitations, as well as examples of their current applications. (topical review)

  5. A computational model to investigate the effect of pennation angle on surface electromyogram of Tibialis Anterior.

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    Diptasree Maitra Ghosh

    Full Text Available This study has described and experimentally validated the differential electrodes surface electromyography (sEMG model for tibialis anterior muscles during isometric contraction. This model has investigated the effect of pennation angle on the simulated sEMG signal. The results show that there is no significant effect of pennation angle in the range 0° to 20° to the single fibre action potential shape recorded on the skin surface. However, the changes with respect to pennation angle are observed in sEMG amplitude, frequency and fractal dimension. It is also observed that at different levels of muscle contractions there is similarity in the relationships with Root Mean Square, Median Frequency, and Fractal Dimension of the recorded and simulated sEMG signals.

  6. Quantify work load and muscle functional activation patterns in neck-shoulder muscles of female sewing machine operators using surface electromyogram.

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    Zhang, Fei-Ruo; He, Li-Hua; Wu, Shan-Shan; Li, Jing-Yun; Ye, Kang-Pin; Wang, Sheng

    2011-11-01

    Work-related musculoskeletal disorders (WMSDs) have high prevalence in sewing machine operators employed in the garment industry. Long work duration, sustained low level work and precise hand work are the main risk factors of neck-shoulder disorders for sewing machine operators. Surface electromyogram (sEMG) offers a valuable tool to determine muscle activity (internal exposure) and quantify muscular load (external exposure). During sustained and/or repetitive muscle contractions, typical changes of muscle fatigue in sEMG, as an increase in amplitude or a decrease as a shift in spectrum towards lower frequencies, can be observed. In this paper, we measured and quantified the muscle load and muscular activity patterns of neck-shoulder muscles in female sewing machine operators during sustained sewing machine operating tasks using sEMG. A total of 18 healthy women sewing machine operators volunteered to participate in this study. Before their daily sewing machine operating task, we measured the maximal voluntary contractions (MVC) and 20%MVC of bilateral cervical erector spinae (CES) and upper trapezius (UT) respectively, then the sEMG signals of bilateral UT and CES were monitored and recorded continuously during 200 minutes of sustained sewing machine operating simultaneously which equals to 20 time windows with 10 minutes as one time window. After 200 minutes' work, we retest 20%MVC of four neck-shoulder muscles and recorded the sEMG signals. Linear analysis, including amplitude probability distribution frequency (APDF), amplitude analysis parameters such as roof mean square (RMS) and spectrum analysis parameter as median frequency (MF), were used to calculate and indicate muscle load and muscular activity of bilateral CES and UT. During 200 minutes of sewing machine operating, the median load for the left cervical erector spinae (LCES), right cervical erector spinae (RCES), left upper trapezius (LUT) and right upper trapezius (RUT) were 6.78%MVE, 6.94%MVE, 6

  7. Wavelet-based unsupervised learning method for electrocardiogram suppression in surface electromyograms.

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    Niegowski, Maciej; Zivanovic, Miroslav

    2016-03-01

    We present a novel approach aimed at removing electrocardiogram (ECG) perturbation from single-channel surface electromyogram (EMG) recordings by means of unsupervised learning of wavelet-based intensity images. The general idea is to combine the suitability of certain wavelet decomposition bases which provide sparse electrocardiogram time-frequency representations, with the capacity of non-negative matrix factorization (NMF) for extracting patterns from images. In order to overcome convergence problems which often arise in NMF-related applications, we design a novel robust initialization strategy which ensures proper signal decomposition in a wide range of ECG contamination levels. Moreover, the method can be readily used because no a priori knowledge or parameter adjustment is needed. The proposed method was evaluated on real surface EMG signals against two state-of-the-art unsupervised learning algorithms and a singular spectrum analysis based method. The results, expressed in terms of high-to-low energy ratio, normalized median frequency, spectral power difference and normalized average rectified value, suggest that the proposed method enables better ECG-EMG separation quality than the reference methods. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  8. Optimal spatio-temporal filter for the reduction of crosstalk in surface electromyogram

    Science.gov (United States)

    Mesin, Luca

    2018-02-01

    Objective. Crosstalk can pose limitations to the applications of surface electromyogram (EMG). Its reduction can help in the identification of the activity of specific muscles. The selectivity of different spatial filters was tested in the literature both in simulations and experiments: their performances are affected by many factors (e.g. anatomy, conduction properties of the tissues and dimension/location of the electrodes); moreover, they reduce crosstalk by decreasing the detection volume, recording data that represent only the activity of a small portion of the muscle of interest. In this study, an alternative idea is proposed, based on a spatio-temporal filter. Approach. An adaptive method is applied, which filters both in time and among different channels, providing a signal that maximally preserves the energy of the EMG of interest and discards that of nearby muscles (increasing the signal to crosstalk ratio, SCR). Main results. Tests with simulations and experimental data show an average increase of the SCR of about 2 dB with respect to the single or double differential data processed by the filter. This allows to reduce the bias induced by crosstalk in conduction velocity and force estimation. Significance. The method can be applied to few channels, so that it is useful in applicative studies (e.g. clinics, gate analysis, rehabilitation protocols with EMG biofeedback and prosthesis control) where limited and not selective information is usually available.

  9. A method for a categorized and probabilistic analysis of the surface electromyogram in dynamic contractions

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    Sylvie Charlotte Frieda Anneliese von Werder

    2015-02-01

    Full Text Available The human motor system permits a wide variety of complex movements. Thereby, the inter- individual variability as well as the biomechanical aspects of the performed movement itself contribute to the challenge of the interpretation of sEMG signals in dynamic contractions. A procedure for the systematic analysis of sEMG recordings during dynamic contraction was introduced, which includes categorization of the data in combination with the analysis of frequency distributions of the sEMG with a probabilistic approach. Using the example of elbow flexion and extension the procedure was evaluated with 10 healthy subjects. The recorded sEMG signals of brachioradialis were categorized into a combination of constant and variable movement factors, which originate from the performed movement. Subsequently, for each combination of movement factors cumulative frequency distributions were computed for each subject separately. Finally, the probability of the difference of muscular activation in varying movement conditions was assessed. The probabilistic approach was compared to a deterministic analysis of the same data. Both approaches observed a significant change of muscular activation of brachioradialis during concentric and eccentric contractions exclusively for flexion and extension angles exceeding 30°. However, with the probabilistic approach additional information on the likelihood that the tested effect occurs can be provided.Especially for movements under uncontrollable boundary conditions, this information to assess the confidence of the detected results is of high relevance. Thus, the procedure provides new insights into the quantification and interpretation of muscular activity.

  10. Surface electromyogram analysis of the direction of isometric torque generation by the first dorsal interosseous muscle

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    Zhou, Ping; Suresh, Nina L.; Zev Rymer, William

    2011-06-01

    The objective of this study was to determine whether a novel technique using high density surface electromyogram (EMG) recordings can be used to detect the directional dependence of muscle activity in a multifunctional muscle, the first dorsal interosseous (FDI). We used surface EMG recordings with a two-dimensional electrode array to search for inhomogeneous FDI activation patterns with changing torque direction at the metacarpophalangeal joint, the locus of action of the FDI muscle. The interference EMG distribution across the whole FDI muscle was recorded during isometric contraction at the same force magnitude in five different directions in the index finger abduction-flexion plane. The electrode array EMG activity was characterized by contour plots, interpolating the EMG amplitude between electrode sites. Across all subjects the amplitude of the flexion EMG was consistently lower than that of the abduction EMG at the given force. Pattern recognition methods were used to discriminate the isometric muscle contraction tasks with a linear discriminant analysis classifier, based on the extraction of two different feature sets of the surface EMG signal: the time domain (TD) feature set and a combination of autoregressive coefficients and the root mean square amplitude (AR+RMS) as a feature set. We found that high accuracies were obtained in the classification of different directions of the FDI muscle isometric contraction. With a monopolar electrode configuration, the average overall classification accuracy from nine subjects was 94.1 ± 2.3% for the TD feature set and 95.8 ± 1.5% for the AR+RMS feature set. Spatial filtering of the signal with bipolar electrode configuration improved the average overall classification accuracy to 96.7 ± 2.7% for the TD feature set and 98.1 ± 1.6% for the AR+RMS feature set. The distinct EMG contour plots and the high classification accuracies obtained from this study confirm distinct interference EMG pattern distributions as a

  11. Muscular Activities Measurements of Forward Lean and Upright Sitting Motorcycling Postures via Surface Electromyography (sEMG

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    Ma’arof Muhammad Izzat Nor

    2017-01-01

    Full Text Available Motorcycling postures are generically speculated to be physical and physiologically demanding – which in-turn may lead to motorcycling fatigue, and then becoming a possible factor to road accident. The objective of this study was to measure the muscular activities of various motorcycling postures. High muscular activity reading will signifies that motorcycling is indeed physically and physiologically demanding to the motorcyclist. For this particular study, the following postures were tested: i forward lean, ii upright sitting, and iii neutral sitting (as control. Surface electromyography (sEMG measurement was conducted on the following muscles: i extensor carpi radialis, ii upper trapezius iii latissimus dorsi, and iv erector spinae. The results showed that for all test subjects, the muscular activities readings for the forward lean posture was actually close to neutral sitting’s. Whilst, the upright sitting had showed much higher muscular activities measurement instead. Conclusively, this study had proven that any types of discomforts associated with the forward lean posture is not originated from muscular activities. Whereas, confirming that any discomforts in regards to the upright sitting is indeed related to muscular activities. Further studies are warranted to discover the actual risk factors that causes physical and physiological discomforts for the forward lean motorcycling posture.

  12. Investigation of the load on the lumbar region in nursing technique's movements - relation between twist and surface electromyogram.

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    Maekawa, Yasuko; Shiozaki, Akira; Majima, Yukie

    2009-01-01

    This study measured the twist angle of the lumbar region and the surface electromyogram (EMG) and examined their mutual relation to elucidate the degree and influence of factors of "twist" in nursing techniques as a cause of lower back pain. Using a goniometer (two-way angle and twist sensors) and an EMG(SX230; DKH Co., Ltd.), we conducted measurements by affixing the goniometer on the lumbar vertebral column and EMG sensor at four points of right and left sides of L2 and L4 (of the erector muscle of the spine). The measured nursing techniques were three common methods of "transferring a patient from bed to wheelchair," which is said to impart a heavy load on the lumbar region. Results show that the correlation value between the twist angle rate and mean energy is likely to be greater, suggesting that the magnitude of the load on the lumbar region should be related to the twist speed rather than to the twist angle of the movement itself.

  13. Estimation of Handgrip Force from SEMG Based on Wavelet Scale Selection.

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    Wang, Kai; Zhang, Xianmin; Ota, Jun; Huang, Yanjiang

    2018-02-24

    This paper proposes a nonlinear correlation-based wavelet scale selection technology to select the effective wavelet scales for the estimation of handgrip force from surface electromyograms (SEMG). The SEMG signal corresponding to gripping force was collected from extensor and flexor forearm muscles during the force-varying analysis task. We performed a computational sensitivity analysis on the initial nonlinear SEMG-handgrip force model. To explore the nonlinear correlation between ten wavelet scales and handgrip force, a large-scale iteration based on the Monte Carlo simulation was conducted. To choose a suitable combination of scales, we proposed a rule to combine wavelet scales based on the sensitivity of each scale and selected the appropriate combination of wavelet scales based on sequence combination analysis (SCA). The results of SCA indicated that the scale combination VI is suitable for estimating force from the extensors and the combination V is suitable for the flexors. The proposed method was compared to two former methods through prolonged static and force-varying contraction tasks. The experiment results showed that the root mean square errors derived by the proposed method for both static and force-varying contraction tasks were less than 20%. The accuracy and robustness of the handgrip force derived by the proposed method is better than that obtained by the former methods.

  14. The assessment of muscle strain with surface electromyograms during simulated mushroom picking

    DEFF Research Database (Denmark)

    Ohashi, Jun-Ya; Blangsted, Anne Katrine; Kofoed Nielsen, Pernille B.

    2008-01-01

    Muscle strain was assessed with surface EMG during simulated mushroom picking. Nine female subjects performed five periods of work (W1-W5). The duration of each period was about 20 min. W1, W2 and W3 were separated by a short break of several minutes. W3, W4 and W5 were separated by a rest period...... in the trapezius was interpreted as spare capacity for the work. The infraspinatus and deltoid were assessed to be more fatigued than the trapezius. The fatigue level of the erector spinae was low....

  15. Assessing the Therapeutic Effect of 630 nm Light-Emitting Diodes Irradiation on the Recovery of Exercise-Induced Hand Muscle Fatigue with Surface Electromyogram

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    Dandan Yang

    2012-01-01

    Full Text Available This paper aims to investigate the effect of light emitting diode therapy (LEDT on exercise-induced hand muscle fatigue by measuring the surface electromyography (sEMG of flexor digitorum superficialis. Ten healthy volunteers were randomly placed in the equal sized LEDT group and control group. All subjects performed a sustained fatiguing isometric contraction with the combination of four fingertips except thumb at 30% of maximal voluntary contraction (MVC until exhaustion. The active LEDT or an identical passive rest therapy was then applied to flexor digitorum superficialis. Each subject was required to perform a re-fatigue task immediately after therapy which was the same as the pre-fatigue task. Average rectified value (ARV and fractal dimension (FD of sEMG were calculated. ARV and FD were significantly different between active LEDT and passive rest groups at 20%–50%, 70%–80%, and 100% of normalized contraction time (P<0.05. Compared to passive rest, active LEDT induced significantly smaller increase in ARV values and decrease in FD values, which shows that LEDT is effective on the recovery of muscle fatigue. Our preliminary results also suggest that ARV and FD are potential replacements of biochemical markers to assess the effects of LEDT on muscle fatigue.

  16. sEMG Signal Acquisition Strategy towards Hand FES Control

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    Cinthya Lourdes Toledo-Peral

    2018-01-01

    Full Text Available Due to damage of the nervous system, patients experience impediments in their daily life: severe fatigue, tremor or impaired hand dexterity, hemiparesis, or hemiplegia. Surface electromyography (sEMG signal analysis is used to identify motion; however, standardization of electrode placement and classification of sEMG patterns are major challenges. This paper describes a technique used to acquire sEMG signals for five hand motion patterns from six able-bodied subjects using an array of recording and stimulation electrodes placed on the forearm and its effects over functional electrical stimulation (FES and volitional sEMG combinations, in order to eventually control a sEMG-driven FES neuroprosthesis for upper limb rehabilitation. A two-part protocol was performed. First, personalized templates to place eight sEMG bipolar channels were designed; with these data, a universal template, called forearm electrode set (FELT, was built. Second, volitional and evoked movements were recorded during FES application. 95% classification accuracy was achieved using two sessions per movement. With the FELT, it was possible to perform FES and sEMG recordings simultaneously. Also, it was possible to extract the volitional and evoked sEMG from the raw signal, which is highly important for closed-loop FES control.

  17. Influences of combined therapies with traditional Chinese medicine on pulmonary function and surface average electromyogram ratio in adolescent idiopathic scoliosis patients

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    Jia-ping SHEN

    2016-09-01

    Full Text Available Objective  To evaluate the influences of traditional Chinese medicinal combined therapies on pulmonary function and surface average electromyogram (AEMG ratio in adolescent idiopathic scoliosis patients. Methods  One hundred and twenty outpatients with mild and moderate adolescent idiopathic scoliosis were randomly divided into a Traditional Chinese Medicine (TCM group and a brace group. TCM group patients underwent i Navigation of the spinal balance (twice a day, 40min/ time, until to skeletal maturity; ii Balance manipulation (twice a week, 25min/time, lasted 12 months; iii Small needle-knife therapy (once a week, 10 times. The brace group patients were treated with a Milwaukee brace. The Cobb angle was measured after 12 and 24 months of treatment, pulmonary function was determined after 12 months of treatment, and AEMG ratio of the surface electromyogram was measured 6, 12, 18 and 24 months after treatment, and intergroup comparison was performed. Results  The Cobb angle significantly decreased in both groups 12 months after treatment (P0.05 in the TCM group and brace group, respectively, 12 months after treatment and 62.5% and 34.7% (P<0.05, respectively, 24 months aftertreatment. Pulmonary function was significantly improved 12 months after treatment in TCM group (P<0.05 but significantly decreased in brace group (P<0.05. The AEMG ratio was significantly reduced (P<0.01 and tended to remain at 1 after stopping treatment in TCM group, showed that the muscle imbalance existed on both sides of the scoliosis, but was adverse in brace group (P<0.05, showed that the muscle imbalance aggravated. No side effect of the therapeutic method was found. Conclusions  The spinal balance therapy based on traditional Chinese medicine theory has excellent therapeutic efficacy and safety, and can significantly ameliorate the imbalance existed on both sides of the scoliosis, improve lung function index, and have better compliance. The AEMG ratio is a

  18. Towards Whole Body Fatigue Assessment of Human Movement: A Fatigue-Tracking System Based on Combined sEMG and Accelerometer Signals

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    Haiwei Dong

    2014-01-01

    Full Text Available This paper proposes a method to assess the overall fatigue of human body movement. First of all, according to previous research regarding localized muscular fatigue, a linear relation is assumed between the mean frequency and the muscular working time when the muscle is experiencing fatigue. This assumption is verified with a rigorous statistical analysis. Based on this proven linearity, localized muscular fatigue is simplified as a linear model. Furthermore, localized muscular fatigue is considered a dynamic process and, hence, the localized fatigue levels are tracked by updating the parameters with the most current surface electromyogram (sEMG measurements. Finally, an overall fatigue level is computed by fusing localized muscular fatigue levels. The developed fatigue-tracking system is evaluated with two fatigue experiments (in which 10 male subjects and seven female subjects participated, including holding self-weight (dip start position training and lifting weight with one arm (arm curl training.

  19. SEMG analysis of astronaut upper arm during isotonic muscle actions with normal standing posture

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    Qianxiang, Zhou; Chao, Ma; Xiaohui, Zheng

    sEMG analysis of astronaut upper arm during isotonic muscle actions with normal standing posture*1 Introduction Now the research on the isotonic muscle actions by using Surface Electromyography (sEMG) is becoming a pop topic in fields of astronaut life support training and rehabilitations. And researchers paid more attention on the sEMG signal processes for reducing the influence of noise which is produced during monitoring process and the fatigue estimation of isotonic muscle actions with different force levels by using the parameters which are obtained from sEMG signals such as Condition Velocity(CV), Median Frequency(MDF), Mean Frequency(MNF) and so on. As the lucubrated research is done, more and more research on muscle fatigue issue of isotonic muscle actions are carried out with sEMG analysis and subjective estimate system of Borg scales at the same time. In this paper, the relationship between the variable for fatigue based on sEMG and the Borg scale during the course of isotonic muscle actions of the upper arm with different contraction levels are going to be investigated. Methods 13 young male subjects(23.4±2.45years, 64.7±5.43Kg, 171.7±5.41cm) with normal standing postures were introduced to do isotonic actions of the upper arm with different force levels(10% MVC, 30%MVC and 50%MVC). And the MVC which means maximal voluntary contraction was obtained firstly in the experiment. Also the sEMG would be recorded during the experiments; the Borg scales would be recorded for each contraction level. By using one-third band octave method, the fatigue variable (p) based on sEMG were set up and it was expressed as p = i g(fi ) · F (fi ). And g(fi ) is defined as the frequent factor which was 0.42+0.5 cos(π fi /f0 )+0.08 cos(2π fi /f0 ), 0 f0 . According to the equations, the p could be computed and the relationship between variable p and the Borg scale would be investigated. Results In the research, three kinds of fitted curves between variable p and Borg

  20. Onset Detection in Surface Electromyographic Signals: A Systematic Comparison of Methods

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    Claus Flachenecker

    2001-06-01

    Full Text Available Various methods to determine the onset of the electromyographic activity which occurs in response to a stimulus have been discussed in the literature over the last decade. Due to the stochastic characteristic of the surface electromyogram (SEMG, onset detection is a challenging task, especially in weak SEMG responses. The performance of the onset detection methods were tested, mostly by comparing their automated onset estimations to the manually determined onsets found by well-trained SEMG examiners. But a systematic comparison between methods, which reveals the benefits and the drawbacks of each method compared to the other ones and shows the specific dependence of the detection accuracy on signal parameters, is still lacking. In this paper, several classical threshold-based approaches as well as some statistically optimized algorithms were tested on large samples of simulated SEMG data with well-known signal parameters. Rating between methods is performed by comparing their performance to that of a statistically optimal maximum likelihood estimator which serves as reference method. In addition, performance was evaluated on real SEMG data obtained in a reaction time experiment. Results indicate that detection behavior strongly depends on SEMG parameters, such as onset rise time, signal-to-noise ratio or background activity level. It is shown that some of the threshold-based signal-power-estimation procedures are very sensitive to signal parameters, whereas statistically optimized algorithms are generally more robust.

  1. An Embedded, Eight Channel, Noise Canceling, Wireless, Wearable sEMG Data Acquisition System With Adaptive Muscle Contraction Detection.

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    Ergeneci, Mert; Gokcesu, Kaan; Ertan, Erhan; Kosmas, Panagiotis

    2018-02-01

    Wearable technology has gained increasing popularity in the applications of healthcare, sports science, and biomedical engineering in recent years. Because of its convenient nature, the wearable technology is particularly useful in the acquisition of the physiological signals. Specifically, the (surface electromyography) sEMG systems, which measure the muscle activation potentials, greatly benefit from this technology in both clinical and industrial applications. However, the current wearable sEMG systems have several drawbacks including inefficient noise cancellation, insufficient measurement quality, and difficult integration to customized applications. Additionally, none of these sEMG data acquisition systems can detect sEMG signals (i.e., contractions), which provides a valuable environment for further studies such as human machine interaction, gesture recognition, and fatigue tracking. To this end, we introduce an embedded, eight channel, noise canceling, wireless, wearable sEMG data acquisition system with adaptive muscle contraction detection. Our design consists of two stages, which are the sEMG sensors and the multichannel data acquisition unit. For the first stage, we propose a low cost, dry, and active sEMG sensor that captures the muscle activation potentials, a data acquisition unit that evaluates these captured multichannel sEMG signals and transmits them to a user interface. In the data acquisition unit, the sEMG signals are processed through embedded, adaptive methods in order to reject the power line noise and detect the muscle contractions. Through extensive experiments, we demonstrate that our sEMG sensor outperforms a widely used commercially available product and our data acquisition system achieves 4.583 dB SNR gain with accuracy in the detection of the contractions.

  2. A Wireless sEMG Recording System and Its Application to Muscle Fatigue Detection

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    Chang, Kang-Ming; Liu, Shin-Hong; Wu, Xuan-Han

    2012-01-01

    Surface electromyography (sEMG) is an important measurement for monitoring exercise and fitness. Because if its high sampling frequency requirement, wireless transmission of sEMG data is a challenge. In this article a wireless sEMG measurement system with a sampling frequency of 2 KHz is developed based upon a MSP 430 microcontroller and Bluetooth transmission. Standard isotonic and isometric muscle contraction are clearly represented in the receiving user interface. Muscle fatigue detection is an important application of sEMG. Traditional muscle fatigue is detected from the median frequency of the sEMG power spectrum. The regression slope of the linear regression of median frequency is an important muscle fatigue index. A more negative slope value represents a higher muscle fatigue condition. To test the system performance, muscle fatigue detection was examined by having subjects run on a pedaled-multifunctional elliptical trainer for approximately 30 minutes at three loading levels. Ten subjects underwent a total of 60 exercise sessions to provide the experimental data. Results showed that the regression slope gradually decreases as expected, and there is a significant gender difference. PMID:22368481

  3. A Wireless sEMG Recording System and Its Application to Muscle Fatigue Detection

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    Xuan-Han Wu

    2012-01-01

    Full Text Available Surface electromyography (sEMG is an important measurement for monitoring exercise and fitness. Because if its high sampling frequency requirement, wireless transmission of sEMG data is a challenge. In this article a wireless sEMG measurement system with a sampling frequency of 2 KHz is developed based upon a MSP 430 microcontroller and Bluetooth transmission. Standard isotonic and isometric muscle contraction are clearly represented in the receiving user interface. Muscle fatigue detection is an important application of sEMG. Traditional muscle fatigue is detected from the median frequency of the sEMG power spectrum. The regression slope of the linear regression of median frequency is an important muscle fatigue index. A more negative slope value represents a higher muscle fatigue condition. To test the system performance, muscle fatigue detection was examined by having subjects run on a pedaled-multifunctional elliptical trainer for approximately 30 minutes at three loading levels. Ten subjects underwent a total of 60 exercise sessions to provide the experimental data. Results showed that the regression slope gradually decreases as expected, and there is a significant gender difference.

  4. Influence of muscular fatigue in evoked electromyogram

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    Fernandez, J; Acevedo, R; Tabernig, C [Rehabilitation Engineering and Neuromuscular and Sensorial Research Laboratory, National University of Entre Rios (Argentina)

    2007-11-15

    In this work we present the results of the evaluation of the changes happened in M wave during application of functional electrical stimulation. Electromyogram from the tibialis anterior muscle and ankle angle were measured to determine the occurrence of the fatigue phenomenon. The results report a decrease of the signal amplitude and the median of the power spectrum and are encouraging for the development of strategies of control of FES applications.

  5. ANALYSIS AND PROCESSING OF ELECTROMYOGRAM SIGNALS

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    K. A. Zimenko

    2013-01-01

    Full Text Available A method of electromyogram signals processing and identification for implementation in rehabilitation devices control is given. The method is based on the high-frequency components filtration which improves the signal/noise ratio; also it is based on the wavelet analysis for signal preprocessing and motion type classification by taught artificial neural network. Obtained accuracy of motion type classification is 94%.

  6. Muscle fatigue evaluation of astronaut upper limb based on sEMG and subjective assessment

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    Zu, Xiaoqi; Zhou, Qianxiang; Li, Yun

    2012-07-01

    All movements are driven by muscle contraction, and it is easy to cause muscle fatigue. Evaluation of muscle fatigue is a hot topic in the area of astronaut life support training and rehabilitation. If muscle gets into fatigue condition, it may reduce work efficiency and has an impact on psychological performance. Therefore it is necessary to develop an accurate and usable method on muscle fatigue evaluation of astronaut upper limb. In this study, we developed a method based on surface electromyography (sEMG) and subjective assessment (Borg scale) to evaluate local muscle fatigue. Fifteen healthy young male subjects participated in the experiment. They performed isometric muscle contractions of the upper limb. sEMG of the biceps brachii were recorded during the entire process of isotonic muscle contraction and Borg scales of muscle fatigue were collected in certain times. sEMG were divided into several parts, and then mean energy of each parts were calculated by the one-twelfth band octave method. Equations were derived based on the relationship between the mean energy of sEMG and Borg scale. The results showed that cubic curve could describe the degree of local muscle fatigue, and could be used to evaluate and monitor local muscle fatigue during the entire process.

  7. Detection of Simulated Vocal Dysfunctions Using Complex sEMG Patterns.

    Science.gov (United States)

    Smith, Nicholas R; Rivera, Luis A; Dietrich, Maria; Shyu, Chi-Ren; Page, Matthew P; DeSouza, Guilherme N

    2016-05-01

    Symptoms of voice disorder may range from slight hoarseness to complete loss of voice; from modest vocal effort to uncomfortable neck pain. But even minor symptoms may still impact personal and especially professional lives. While early detection and diagnosis can ameliorate that effect, to date, we are still largely missing reliable and valid data to help us better screen for voice disorders. In our previous study, we started to address this gap in research by introducing an ambulatory voice monitoring system using surface electromyography (sEMG) and a robust algorithm (HiGUSSS) for pattern recognition of vocal gestures. Here, we expand on that work by further analyzing a larger set of simulated vocal dysfunctions. Our goal is to demonstrate that such a system has the potential to recognize and detect real vocal dysfunctions from multiple individuals with high accuracy under both intra and intersubject conditions. The proposed system relies on four sEMG channels to simultaneously process various patterns of sEMG activation in the search for maladaptive laryngeal activity that may lead to voice disorders. In the results presented here, our pattern recognition algorithm detected from two to ten different classes of sEMG patterns of muscle activation with an accuracy as high as 99%, depending on the subject and the testing conditions.

  8. Robust functional statistics applied to Probability Density Function shape screening of sEMG data.

    Science.gov (United States)

    Boudaoud, S; Rix, H; Al Harrach, M; Marin, F

    2014-01-01

    Recent studies pointed out possible shape modifications of the Probability Density Function (PDF) of surface electromyographical (sEMG) data according to several contexts like fatigue and muscle force increase. Following this idea, criteria have been proposed to monitor these shape modifications mainly using High Order Statistics (HOS) parameters like skewness and kurtosis. In experimental conditions, these parameters are confronted with small sample size in the estimation process. This small sample size induces errors in the estimated HOS parameters restraining real-time and precise sEMG PDF shape monitoring. Recently, a functional formalism, the Core Shape Model (CSM), has been used to analyse shape modifications of PDF curves. In this work, taking inspiration from CSM method, robust functional statistics are proposed to emulate both skewness and kurtosis behaviors. These functional statistics combine both kernel density estimation and PDF shape distances to evaluate shape modifications even in presence of small sample size. Then, the proposed statistics are tested, using Monte Carlo simulations, on both normal and Log-normal PDFs that mimic observed sEMG PDF shape behavior during muscle contraction. According to the obtained results, the functional statistics seem to be more robust than HOS parameters to small sample size effect and more accurate in sEMG PDF shape screening applications.

  9. SEMG activity of jaw-closing muscles during biting with different unilateral occlusal supports.

    Science.gov (United States)

    Wang, M-Q; He, J-J; Zhang, J-H; Wang, K; Svensson, P; Widmalm, S E

    2010-09-01

    The aim of this study was to test the hypothesis that experimental and reversible changes of occlusion affect the levels of surface electromyographic (SEMG) activity in the anterior temporalis and masseter areas during unilateral maximal voluntary biting (MVB) in centric and eccentric position. Changes were achieved by letting 21 healthy subjects bite with and without a cotton roll between the teeth. The placement alternated between sides and between premolar and molar areas. The SEMG activity level was lower when biting in eccentric position without than with a cotton roll between teeth (P 0.05). In the anterior temporalis area, the balancing side SEMG activity was lower in eccentric than in centric but only in molar-supported biting (P = 0.026). These results support that the masseter and anterior temporalis muscles have different roles in keeping the mandible in balance during unilateral supported MVB. Changes in occlusal stability achieved by biting with versus without a cotton roll were found to affect the SEMG activity levels.

  10. S-EMG signal compression based on domain transformation and spectral shape dynamic bit allocation.

    Science.gov (United States)

    Trabuco, Marcel Henrique; Costa, Marcus Vinícius Chaffim; Nascimento, Francisco Assis de Oliveira

    2014-02-27

    Surface electromyographic (S-EMG) signal processing has been emerging in the past few years due to its non-invasive assessment of muscle function and structure and because of the fast growing rate of digital technology which brings about new solutions and applications. Factors such as sampling rate, quantization word length, number of channels and experiment duration can lead to a potentially large volume of data. Efficient transmission and/or storage of S-EMG signals are actually a research issue. That is the aim of this work. This paper presents an algorithm for the data compression of surface electromyographic (S-EMG) signals recorded during isometric contractions protocol and during dynamic experimental protocols such as the cycling activity. The proposed algorithm is based on discrete wavelet transform to proceed spectral decomposition and de-correlation, on a dynamic bit allocation procedure to code the wavelets transformed coefficients, and on an entropy coding to minimize the remaining redundancy and to pack all data. The bit allocation scheme is based on mathematical decreasing spectral shape models, which indicates a shorter digital word length to code high frequency wavelets transformed coefficients. Four bit allocation spectral shape methods were implemented and compared: decreasing exponential spectral shape, decreasing linear spectral shape, decreasing square-root spectral shape and rotated hyperbolic tangent spectral shape. The proposed method is demonstrated and evaluated for an isometric protocol and for a dynamic protocol using a real S-EMG signal data bank. Objective performance evaluations metrics are presented. In addition, comparisons with other encoders proposed in scientific literature are shown. The decreasing bit allocation shape applied to the quantized wavelet coefficients combined with arithmetic coding results is an efficient procedure. The performance comparisons of the proposed S-EMG data compression algorithm with the established

  11. sEMG during Whole-Body Vibration Contains Motion Artifacts and Reflex Activity

    Directory of Open Access Journals (Sweden)

    Karin Lienhard

    2015-01-01

    Full Text Available The purpose of this study was to determine whether the excessive spikes observed in the surface electromyography (sEMG spectrum recorded during whole-body vibration (WBV exercises contain motion artifacts and/or reflex activity. The occurrence of motion artifacts was tested by electrical recordings of the patella. The involvement of reflex activity was investigated by analyzing the magnitude of the isolated spikes during changes in voluntary background muscle activity. Eighteen physically active volunteers performed static squats while the sEMG was measured of five lower limb muscles during vertical WBV using no load and an additional load of 33 kg. In order to record motion artifacts during WBV, a pair of electrodes was positioned on the patella with several layers of tape between skin and electrodes. Spectral analysis of the patella signal revealed recordings of motion artifacts as high peaks at the vibration frequency (fundamental and marginal peaks at the multiple harmonics were observed. For the sEMG recordings, the root mean square of the spikes increased with increasing additional loads (p < 0.05, and was significantly correlated to the sEMG signal without the spikes of the respective muscle (r range: 0.54 - 0.92, p < 0.05. This finding indicates that reflex activity might be contained in the isolated spikes, as identical behavior has been found for stretch reflex responses evoked during direct vibration. In conclusion, the spikes visible in the sEMG spectrum during WBV exercises contain motion artifacts and possibly reflex activity.

  12. A Spiking Neural Network in sEMG Feature Extraction.

    Science.gov (United States)

    Lobov, Sergey; Mironov, Vasiliy; Kastalskiy, Innokentiy; Kazantsev, Victor

    2015-11-03

    We have developed a novel algorithm for sEMG feature extraction and classification. It is based on a hybrid network composed of spiking and artificial neurons. The spiking neuron layer with mutual inhibition was assigned as feature extractor. We demonstrate that the classification accuracy of the proposed model could reach high values comparable with existing sEMG interface systems. Moreover, the algorithm sensibility for different sEMG collecting systems characteristics was estimated. Results showed rather equal accuracy, despite a significant sampling rate difference. The proposed algorithm was successfully tested for mobile robot control.

  13. A two-dimensional matrix image based feature extraction method for classification of sEMG: A comparative analysis based on SVM, KNN and RBF-NN.

    Science.gov (United States)

    Wen, Tingxi; Zhang, Zhongnan; Qiu, Ming; Zeng, Ming; Luo, Weizhen

    2017-01-01

    The computer mouse is an important human-computer interaction device. But patients with physical finger disability are unable to operate this device. Surface EMG (sEMG) can be monitored by electrodes on the skin surface and is a reflection of the neuromuscular activities. Therefore, we can control limbs auxiliary equipment by utilizing sEMG classification in order to help the physically disabled patients to operate the mouse. To develop a new a method to extract sEMG generated by finger motion and apply novel features to classify sEMG. A window-based data acquisition method was presented to extract signal samples from sEMG electordes. Afterwards, a two-dimensional matrix image based feature extraction method, which differs from the classical methods based on time domain or frequency domain, was employed to transform signal samples to feature maps used for classification. In the experiments, sEMG data samples produced by the index and middle fingers at the click of a mouse button were separately acquired. Then, characteristics of the samples were analyzed to generate a feature map for each sample. Finally, the machine learning classification algorithms (SVM, KNN, RBF-NN) were employed to classify these feature maps on a GPU. The study demonstrated that all classifiers can identify and classify sEMG samples effectively. In particular, the accuracy of the SVM classifier reached up to 100%. The signal separation method is a convenient, efficient and quick method, which can effectively extract the sEMG samples produced by fingers. In addition, unlike the classical methods, the new method enables to extract features by enlarging sample signals' energy appropriately. The classical machine learning classifiers all performed well by using these features.

  14. Automated Algorithm for Generalized Tonic–Clonic Epileptic Seizure Onset Detection Based on sEMG Zero-Crossing Rate

    DEFF Research Database (Denmark)

    Conradsen, Isa; Beniczky, Sándor; Hoppe, Karsten

    2012-01-01

    Patients are not able to call for help during a generalized tonic–clonic epileptic seizure. Our objective was to develop a robust generic algorithm for automatic detection of tonic–clonic seizures, based on surface electromyography (sEMG) signals suitable for a portable device. Twenty-two seizure...

  15. Transforming insect electromyograms into pneumatic muscle control

    Science.gov (United States)

    Rutter, Brandon; Mu, Laiyong; Ritzmann, Roy; Quinn, Roger

    2006-05-01

    Robots can serve as hardware models for testing biological hypotheses. Both for this reason and to improve the state of the art of robotics, we strive to incorporate biological principles of insect locomotion into robotic designs. Previous research has resulted in a line of robots with leg designs based on walking and climbing movements of the cockroach Blaberus discoidalis. The current version, Robot V, uses muscle-like Braided Pneumatic Actuators (BPAs). In this paper, we use recorded electromyograms (EMGs) to drive robot joint motion. A muscle activation model was developed that transforms EMGs recorded from behaving cockroaches into appropriate commands for the robot. The transform is implemented by multiplying the EMG by an input gain thus generating an input pressure signal, which is used to drive a one-way closed loop pressure controller. The actuator then can be modeled as a capacitance with input rectification. The actuator exhaust valve is given a leak rate, making the transform a leaky integrator for air pressure, which drives the output force of the actuator. We find parameters of this transform by minimizing the difference between the robot motion produced and that observed in the cockroach. Although we have not reproduced full-amplitude cockroach motion using this robot, results from evaluation on reduced-amplitude cockroach angle data strongly suggest that braided pneumatic actuators can be used as part of a physical model of a biological system.

  16. Towards an SEMG-based tele-operated robot for masticatory rehabilitation.

    Science.gov (United States)

    Kalani, Hadi; Moghimi, Sahar; Akbarzadeh, Alireza

    2016-08-01

    This paper proposes a real-time trajectory generation for a masticatory rehabilitation robot based on surface electromyography (SEMG) signals. We used two Gough-Stewart robots. The first robot was used as a rehabilitation robot while the second robot was developed to model the human jaw system. The legs of the rehabilitation robot were controlled by the SEMG signals of a tele-operator to reproduce the masticatory motion in the human jaw, supposedly mounted on the moving platform, through predicting the location of a reference point. Actual jaw motions and the SEMG signals from the masticatory muscles were recorded and used as output and input, respectively. Three different methods, namely time-delayed neural networks, time delayed fast orthogonal search, and time-delayed Laguerre expansion technique, were employed and compared to predict the kinematic parameters. The optimal model structures as well as the input delays were obtained for each model and each subject through a genetic algorithm. Equations of motion were obtained by the virtual work method. Fuzzy method was employed to develop a fuzzy impedance controller. Moreover, a jaw model was developed to demonstrate the time-varying behavior of the muscle lengths during the rehabilitation process. The three modeling methods were capable of providing reasonably accurate estimations of the kinematic parameters, although the accuracy and training/validation speed of time-delayed fast orthogonal search were higher than those of the other two aforementioned methods. Also, during a simulation study, the fuzzy impedance scheme proved successful in controlling the moving platform for the accurate navigation of the reference point in the desired trajectory. SEMG has been widely used as a control command for prostheses and exoskeleton robots. However, in the current study by employing the proposed rehabilitation robot the complete continuous profile of the clenching motion was reproduced in the sagittal plane. Copyright

  17. Computational Intelligence Based Data Fusion Algorithm for Dynamic sEMG and Skeletal Muscle Force Modelling

    Energy Technology Data Exchange (ETDEWEB)

    Chandrasekhar Potluri,; Madhavi Anugolu; Marco P. Schoen; D. Subbaram Naidu

    2013-08-01

    In this work, an array of three surface Electrography (sEMG) sensors are used to acquired muscle extension and contraction signals for 18 healthy test subjects. The skeletal muscle force is estimated using the acquired sEMG signals and a Non-linear Wiener Hammerstein model, relating the two signals in a dynamic fashion. The model is obtained from using System Identification (SI) algorithm. The obtained force models for each sensor are fused using a proposed fuzzy logic concept with the intent to improve the force estimation accuracy and resilience to sensor failure or misalignment. For the fuzzy logic inference system, the sEMG entropy, the relative error, and the correlation of the force signals are considered for defining the membership functions. The proposed fusion algorithm yields an average of 92.49% correlation between the actual force and the overall estimated force output. In addition, the proposed fusionbased approach is implemented on a test platform. Experiments indicate an improvement in finger/hand force estimation.

  18. Optimal Elbow Angle for Extracting sEMG Signals During Fatiguing Dynamic Contraction

    Directory of Open Access Journals (Sweden)

    Mohamed R. Al-Mulla

    2015-09-01

    Full Text Available Surface electromyographic (sEMG activity of the biceps muscle was recorded from 13 subjects. Data was recorded while subjects performed dynamic contraction until fatigue and the signals were segmented into two parts (Non-Fatigue and Fatigue. An evolutionary algorithm was used to determine the elbow angles that best separate (using Davies-Bouldin Index, DBI both Non-Fatigue and Fatigue segments of the sEMG signal. Establishing the optimal elbow angle for feature extraction used in the evolutionary process was based on 70% of the conducted sEMG trials. After completing 26 independent evolution runs, the best run containing the optimal elbow angles for separation (Non-Fatigue and Fatigue was selected and then tested on the remaining 30% of the data to measure the classification performance. Testing the performance of the optimal angle was undertaken on nine features extracted from each of the two classes (Non-Fatigue and Fatigue to quantify the performance. Results showed that the optimal elbow angles can be used for fatigue classification, showing 87.90% highest correct classification for one of the features and on average of all eight features (including worst performing features giving 78.45%.

  19. sEMG Sensor Using Polypyrrole-Coated Nonwoven Fabric Sheet for Practical Control of Prosthetic Hand.

    Science.gov (United States)

    Jiang, Yinlai; Togane, Masami; Lu, Baoliang; Yokoi, Hiroshi

    2017-01-01

    One of the greatest challenges of using a myoelectric prosthetic hand in daily life is to conveniently measure stable myoelectric signals. This study proposes a novel surface electromyography (sEMG) sensor using polypyrrole-coated nonwoven fabric sheet as electrodes (PPy electrodes) to allow people with disabilities to control prosthetic limbs. The PPy electrodes are sewn on an elastic band to guarantee close contact with the skin and thus reduce the contact electrical impedance between the electrodes and the skin. The sensor is highly customizable to fit the size and the shape of the stump so that people with disabilities can attach the sensor by themselves. The performance of the proposed sensor was investigated experimentally by comparing measurements of Ag/AgCl electrodes with electrolytic gel and the sEMG from the same muscle fibers. The high correlation coefficient (0.87) between the two types of sensors suggests the effectiveness of the proposed sensor. Another experiment of sEMG pattern recognition to control myoelectric prosthetic hands showed that the PPy electrodes are as effective as Ag/AgCl electrodes for measuring sEMG signals for practical myoelectric control. We also investigated the relation between the myoelectric signals' signal-to-noise ratio and the source impedances by simultaneously measuring the source impedances and the myoelectric signals with a switching circuit. The results showed that differences in both the norm and the phase of the source impedance greatly affect the common mode noise in the signal.

  20. Preliminary Study on Continuous Recognition of Elbow Flexion/Extension Using sEMG Signals for Bilateral Rehabilitation

    Directory of Open Access Journals (Sweden)

    Zhibin Song

    2016-10-01

    Full Text Available Surface electromyography (sEMG signals are closely related to the activation of human muscles and the motion of the human body, which can be used to estimate the dynamics of human limbs in the rehabilitation field. They also have the potential to be used in the application of bilateral rehabilitation, where hemiplegic patients can train their affected limbs following the motion of unaffected limbs via some rehabilitation devices. Traditional methods to process the sEMG focused on motion pattern recognition, namely, discrete patterns, which are not satisfactory for use in bilateral rehabilitation. In order to overcome this problem, in this paper, we built a relationship between sEMG signals and human motion in elbow flexion and extension on the sagittal plane. During the conducted experiments, four participants were required to perform elbow flexion and extension on the sagittal plane smoothly with only an inertia sensor in their hands, where forearm dynamics were not considered. In these circumstances, sEMG signals were weak compared to those with heavy loads or high acceleration. The contrastive experimental results show that continuous motion can also be obtained within an acceptable precision range.

  1. Wireless sEMG System with a Microneedle-Based High-Density Electrode Array on a Flexible Substrate.

    Science.gov (United States)

    Kim, Minjae; Gu, Gangyong; Cha, Kyoung Je; Kim, Dong Sung; Chung, Wan Kyun

    2017-12-30

    Surface electromyography (sEMG) signals reflect muscle contraction and hence, can provide information regarding a user's movement intention. High-density sEMG systems have been proposed to measure muscle activity in small areas and to estimate complex motion using spatial patterns. However, conventional systems based on wet electrodes have several limitations. For example, the electrolyte enclosed in wet electrodes restricts spatial resolution, and these conventional bulky systems limit natural movements. In this paper, a microneedle-based high-density electrode array on a circuit integrated flexible substrate for sEMG is proposed. Microneedles allow for high spatial resolution without requiring conductive substances, and flexible substrates guarantee stable skin-electrode contact. Moreover, a compact signal processing system is integrated with the electrode array. Therefore, sEMG measurements are comfortable to the user and do not interfere with the movement. The system performance was demonstrated by testing its operation and estimating motion using a Gaussian mixture model-based, simplified 2D spatial pattern.

  2. A Discrete-Time Algorithm for Stiffness Extraction from sEMG and Its Application in Antidisturbance Teleoperation

    Directory of Open Access Journals (Sweden)

    Peidong Liang

    2016-01-01

    Full Text Available We have developed a new discrete-time algorithm of stiffness extraction from muscle surface electromyography (sEMG collected from human operator’s arms and have applied it for antidisturbance control in robot teleoperation. The variation of arm stiffness is estimated from sEMG signals and transferred to a telerobot under variable impedance control to imitate human motor control behaviours, particularly for disturbance attenuation. In comparison to the estimation of stiffness from sEMG, the proposed algorithm is able to reduce the nonlinear residual error effect and to enhance robustness and to simplify stiffness calibration. In order to extract a smoothing stiffness enveloping from sEMG signals, two enveloping methods are employed in this paper, namely, fast linear enveloping based on low pass filtering and moving average and amplitude monocomponent and frequency modulating (AM-FM method. Both methods have been incorporated into the proposed stiffness variance estimation algorithm and are extensively tested. The test results show that stiffness variation extraction based on the two methods is sensitive and robust to attenuation disturbance. It could potentially be applied for teleoperation in the presence of hazardous surroundings or human robot physical cooperation scenarios.

  3. Features extraction and multi-classification of sEMG using a GPU-Accelerated GA/MLP hybrid algorithm.

    Science.gov (United States)

    Luo, Weizhen; Zhang, Zhongnan; Wen, Tingxi; Li, Chunfeng; Luo, Ziheng

    2017-01-01

    Surface electromyography (sEMG) signal is the combined effect of superficial muscle EMG and neural electrical activity. In recent years, researchers did large amount of human-machine system studies by using the physiological signals as control signals. To develop and test a new multi-classification method to improve performance of analyzing sEMG signals based on public sEMG dataset. First, ten features were selected as candidate features. Second, a genetic algorithm (GA) was applied to select representative features from the initial ten candidates. Third, a multi-layer perceptron (MLP) classifier was trained by the selected optimal features. Last, the trained classifier was used to predict the classes of sEMG signals. A special graphics processing unit (GPU) was used to speed up the learning process. Experimental results show that the classification accuracy of the new method reached higher than 90%. Comparing to other previously reported results, using the new method yielded higher performance. The proposed features selection method is effective and the classification result is accurate. In addition, our method could have practical application value in medical prosthetics and the potential to improve robustness of myoelectric pattern recognition.

  4. Predicting 3D lip shapes using facial surface EMG

    NARCIS (Netherlands)

    Eskes, Merijn; van Alphen, Maarten J. A.; Balm, Alfons J. M.; Smeele, Ludi E.; Brandsma, Dieta; van der Heijden, Ferdinand

    2017-01-01

    Aim The aim of this study is to prove that facial surface electromyography (sEMG) conveys sufficient information to predict 3D lip shapes. High sEMG predictive accuracy implies we could train a neural control model for activation of biomechanical models by simultaneously recording sEMG signals and

  5. 3D-printing soft sEMG sensing structures

    NARCIS (Netherlands)

    Wolterink, Gerjan; Sanders, Remco; Muijzer, Frodo; van Beijnum, Bert-Jan; Krijnen, Gijs

    2017-01-01

    This paper describes the development and characterization of soft and flexible 3D-printed sEMG electrodes. The electrodes are printed in one go on a low cost consumer multi-material FDM printer. The printed structures do not need any further production steps to give them conductive properties.

  6. Stretchable human-machine interface based on skin-conformal sEMG electrodes with self-similar geometry

    Science.gov (United States)

    Dong, Wentao; Zhu, Chen; Hu, Wei; Xiao, Lin; Huang, Yong'an

    2018-01-01

    Current stretchable surface electrodes have attracted increasing attention owing to their potential applications in biological signal monitoring, wearable human-machine interfaces (HMIs) and the Internet of Things. The paper proposed a stretchable HMI based on a surface electromyography (sEMG) electrode with a self-similar serpentine configuration. The sEMG electrode was transfer-printed onto the skin surface conformally to monitor biological signals, followed by signal classification and controlling of a mobile robot. Such electrodes can bear rather large deformation (such as >30%) under an appropriate areal coverage. The sEMG electrodes have been used to record electrophysiological signals from different parts of the body with sharp curvature, such as the index finger, back of the neck and face, and they exhibit great potential for HMI in the fields of robotics and healthcare. The electrodes placed onto the two wrists would generate two different signals with the fist clenched and loosened. It is classified to four kinds of signals with a combination of the gestures from the two wrists, that is, four control modes. Experiments demonstrated that the electrodes were successfully used as an HMI to control the motion of a mobile robot remotely. Project supported by the National Natural Science Foundation of China (Nos. 51635007, 91323303).

  7. Towards the control of an active hand orthosis for people with Duchenne muscular dystrophy : Design and Validation of a wireless sEMG sleeve

    NARCIS (Netherlands)

    Nizamis, Kostas; Ganseij, Maarten; Koopman, H.F.J.M.

    2017-01-01

    Duchenne Muscular Dystrophy (DMD) is a progressive muscular disease. Active hand orthoses can greatly improve the quality of life of people with DMD. Surface Electromyography (sEMG) is commonly used for the control of active devices. The interfacing between the human and the sensor is regularly done

  8. TOWARDS THE CONTROL OF AN ACTIVE HAND ORTHOSIS FOR PEOPLE WITH DUCHENNE MUSCULAR DYSTROPHY: DESIGN AND VALIDATION OF A WIRELESS SEMG SLEEVE

    NARCIS (Netherlands)

    Nizamis, Kostas; Ganseij, Maarten; Koopman, Hubertus F.J.M.

    2017-01-01

    Duchenne Muscular Dystrophy (DMD) is a progressive muscular disease. Active hand orthoses can greatly improve the quality of life of people with DMD. Surface Electromyography (sEMG) is commonly used for the control of active devices. The interfacing between the human and the sensor is regularly done

  9. A frequency and pulse-width co-modulation strategy for transcutaneous neuromuscular electrical stimulation based on sEMG time-domain features

    Science.gov (United States)

    Zhou, Yu-Xuan; Wang, Hai-Peng; Bao, Xue-Liang; Lü, Xiao-Ying; Wang, Zhi-Gong

    2016-02-01

    Objective. Surface electromyography (sEMG) is often used as a control signal in neuromuscular electrical stimulation (NMES) systems to enhance the voluntary control and proprioceptive sensory feedback of paralyzed patients. Most sEMG-controlled NMES systems use the envelope of the sEMG signal to modulate the stimulation intensity (current amplitude or pulse width) with a constant frequency. The aims of this study were to develop a strategy that co-modulates frequency and pulse width based on features of the sEMG signal and to investigate the torque-reproduction performance and the level of fatigue resistance achieved with our strategy. Approach. We examined the relationships between wrist torque and two stimulation parameters (frequency and pulse width) and between wrist torque and two sEMG time-domain features (mean absolute value (MAV) and number of slope sign changes (NSS)) in eight healthy volunteers. By using wrist torque as an intermediate variable, customized and generalized transfer functions were constructed to convert the two features of the sEMG signal into the two stimulation parameters, thereby establishing a MAV/NSS dual-coding (MNDC) algorithm. Wrist torque reproduction performance was assessed by comparing the torque generated by the algorithms with that originally recorded during voluntary contractions. Muscle fatigue was assessed by measuring the decline percentage of the peak torque and by comparing the torque time integral of the response to test stimulation trains before and after fatigue sessions. Main Results. The MNDC approach could produce a wrist torque that closely matched the voluntary wrist torque. In addition, a smaller decay in the wrist torque was observed after the MNDC-coded fatigue stimulation was applied than after stimulation using pulse-width modulation alone. Significance. Compared with pulse-width modulation stimulation strategies that are based on sEMG detection, the MNDC strategy is more effective for both voluntary muscle

  10. Surface Electromyography for Speech and Swallowing Systems: Measurement, Analysis, and Interpretation

    Science.gov (United States)

    Stepp, Cara E.

    2012-01-01

    Purpose: Applying surface electromyography (sEMG) to the study of voice, speech, and swallowing is becoming increasingly popular. An improved understanding of sEMG and building a consensus as to appropriate methodology will improve future research and clinical applications. Method: An updated review of the theory behind recording sEMG for the…

  11. Multichannel noninvasive human-machine interface via stretchable µm thick sEMG patches for robot manipulation

    Science.gov (United States)

    Zhou, Ying; Wang, Youhua; Liu, Runfeng; Xiao, Lin; Zhang, Qin; Huang, YongAn

    2018-01-01

    Epidermal electronics (e-skin) emerging in recent years offer the opportunity to noninvasively and wearably extract biosignals from human bodies. The conventional processes of e-skin based on standard microelectronic fabrication processes and a variety of transfer printing methods, nevertheless, unquestionably constrains the size of the devices, posing a serious challenge to collecting signals via skin, the largest organ in the human body. Herein we propose a multichannel noninvasive human-machine interface (HMI) using stretchable surface electromyography (sEMG) patches to realize a robot hand mimicking human gestures. Time-efficient processes are first developed to manufacture µm thick large-scale stretchable devices. With micron thickness, the stretchable µm thick sEMG patches show excellent conformability with human skin and consequently comparable electrical performance with conventional gel electrodes. Combined with the large-scale size, the multichannel noninvasive HMI via stretchable µm thick sEMG patches successfully manipulates the robot hand with eight different gestures, whose precision is as high as conventional gel electrodes array.

  12. Transradial Amputee Gesture Classification Using an Optimal Number of sEMG Sensors: An Approach Using ICA Clustering.

    Science.gov (United States)

    Naik, Ganesh R; Al-Timemy, Ali H; Nguyen, Hung T

    2016-08-01

    Surface electromyography (sEMG)-based pattern recognition studies have been widely used to improve the classification accuracy of upper limb gestures. Information extracted from multiple sensors of the sEMG recording sites can be used as inputs to control powered upper limb prostheses. However, usage of multiple EMG sensors on the prosthetic hand is not practical and makes it difficult for amputees due to electrode shift/movement, and often amputees feel discomfort in wearing sEMG sensor array. Instead, using fewer numbers of sensors would greatly improve the controllability of prosthetic devices and it would add dexterity and flexibility in their operation. In this paper, we propose a novel myoelectric control technique for identification of various gestures using the minimum number of sensors based on independent component analysis (ICA) and Icasso clustering. The proposed method is a model-based approach where a combination of source separation and Icasso clustering was utilized to improve the classification performance of independent finger movements for transradial amputee subjects. Two sEMG sensor combinations were investigated based on the muscle morphology and Icasso clustering and compared to Sequential Forward Selection (SFS) and greedy search algorithm. The performance of the proposed method has been validated with five transradial amputees, which reports a higher classification accuracy ( > 95%). The outcome of this study encourages possible extension of the proposed approach to real time prosthetic applications.

  13. Synchronous monitoring of muscle dynamics and electromyogram

    Science.gov (United States)

    Zakir Hossain, M.; Grill, Wolfgang

    2011-04-01

    A non-intrusive novel detection scheme has been implemented to detect the lateral muscle extension, force of the skeletal muscle and the motor action potential (EMG) synchronously. This allows the comparison of muscle dynamics and EMG signals as a basis for modeling and further studies to determine which architectural parameters are most sensitive to changes in muscle activity. For this purpose the transmission time for ultrasonic chirp signal in the frequency range of 100 kHz to 2.5 MHz passing through the muscle under observation and respective motor action potentials are recorded synchronously to monitor and quantify biomechanical parameters related to muscle performance. Additionally an ultrasonic force sensor has been employed for monitoring. Ultrasonic traducers are placed on the skin to monitor muscle expansion. Surface electrodes are placed suitably to pick up the potential for activation of the monitored muscle. Isometric contraction of the monitored muscle is ensured by restricting the joint motion with the ultrasonic force sensor. Synchronous monitoring was initiated by a software activated audio beep starting at zero time of the subsequent data acquisition interval. Computer controlled electronics are used to generate and detect the ultrasonic signals and monitor the EMG signals. Custom developed software and data analysis is employed to analyze and quantify the monitored data. Reaction time, nerve conduction speed, latent period between the on-set of EMG signals and muscle response, degree of muscle activation and muscle fatigue development, rate of energy expenditure and motor neuron recruitment rate in isometric contraction, and other relevant parameters relating to muscle performance have been quantified with high spatial and temporal resolution.

  14. Evaluation of Feature Extraction and Recognition for Activity Monitoring and Fall Detection Based on Wearable sEMG Sensors.

    Science.gov (United States)

    Xi, Xugang; Tang, Minyan; Miran, Seyed M; Luo, Zhizeng

    2017-05-27

    As an essential subfield of context awareness, activity awareness, especially daily activity monitoring and fall detection, plays a significant role for elderly or frail people who need assistance in their daily activities. This study investigates the feature extraction and pattern recognition of surface electromyography (sEMG), with the purpose of determining the best features and classifiers of sEMG for daily living activities monitoring and fall detection. This is done by a serial of experiments. In the experiments, four channels of sEMG signal from wireless, wearable sensors located on lower limbs are recorded from three subjects while they perform seven activities of daily living (ADL). A simulated trip fall scenario is also considered with a custom-made device attached to the ankle. With this experimental setting, 15 feature extraction methods of sEMG, including time, frequency, time/frequency domain and entropy, are analyzed based on class separability and calculation complexity, and five classification methods, each with 15 features, are estimated with respect to the accuracy rate of recognition and calculation complexity for activity monitoring and fall detection. It is shown that a high accuracy rate of recognition and a minimal calculation time for daily activity monitoring and fall detection can be achieved in the current experimental setting. Specifically, the Wilson Amplitude (WAMP) feature performs the best, and the classifier Gaussian Kernel Support Vector Machine (GK-SVM) with Permutation Entropy (PE) or WAMP results in the highest accuracy for activity monitoring with recognition rates of 97.35% and 96.43%. For fall detection, the classifier Fuzzy Min-Max Neural Network (FMMNN) has the best sensitivity and specificity at the cost of the longest calculation time, while the classifier Gaussian Kernel Fisher Linear Discriminant Analysis (GK-FDA) with the feature WAMP guarantees a high sensitivity (98.70%) and specificity (98.59%) with a short

  15. Evaluation of Feature Extraction and Recognition for Activity Monitoring and Fall Detection Based on Wearable sEMG Sensors

    Directory of Open Access Journals (Sweden)

    Xugang Xi

    2017-05-01

    Full Text Available As an essential subfield of context awareness, activity awareness, especially daily activity monitoring and fall detection, plays a significant role for elderly or frail people who need assistance in their daily activities. This study investigates the feature extraction and pattern recognition of surface electromyography (sEMG, with the purpose of determining the best features and classifiers of sEMG for daily living activities monitoring and fall detection. This is done by a serial of experiments. In the experiments, four channels of sEMG signal from wireless, wearable sensors located on lower limbs are recorded from three subjects while they perform seven activities of daily living (ADL. A simulated trip fall scenario is also considered with a custom-made device attached to the ankle. With this experimental setting, 15 feature extraction methods of sEMG, including time, frequency, time/frequency domain and entropy, are analyzed based on class separability and calculation complexity, and five classification methods, each with 15 features, are estimated with respect to the accuracy rate of recognition and calculation complexity for activity monitoring and fall detection. It is shown that a high accuracy rate of recognition and a minimal calculation time for daily activity monitoring and fall detection can be achieved in the current experimental setting. Specifically, the Wilson Amplitude (WAMP feature performs the best, and the classifier Gaussian Kernel Support Vector Machine (GK-SVM with Permutation Entropy (PE or WAMP results in the highest accuracy for activity monitoring with recognition rates of 97.35% and 96.43%. For fall detection, the classifier Fuzzy Min-Max Neural Network (FMMNN has the best sensitivity and specificity at the cost of the longest calculation time, while the classifier Gaussian Kernel Fisher Linear Discriminant Analysis (GK-FDA with the feature WAMP guarantees a high sensitivity (98.70% and specificity (98.59% with a

  16. Limitations of Spectral Electromyogramic Analysis to Determine the Onset of Neuromuscular Fatigue Threshold during Incremental Ergometer Cycling

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    Iban Latasa, Alfredo Cordova, Armando Malanda, Javier Navallas, Ana Lavilla-Oiz, Javier Rodriguez-Falces

    2016-03-01

    Full Text Available Recently, a new method has been proposed to detect the onset of neuromuscular fatigue during an incremental cycling test by assessing the changes in spectral electromyographic (sEMG frequencies within individual exercise periods of the test. The method consists on determining the highest power output that can be sustained without a significant decrease in spectral frequencies. This study evaluated the validity of the new approach by assessing the changes in spectral indicators both throughout the whole test and within individual exercise periods of the test. Fourteen cyclists performed incremental cycle ergometer rides to exhaustion with bipolar surface EMG signals recorded from the vastus lateralis. The mean and median frequencies (Fmean and Fmedian, respectively of the sEMG power spectrum were calculated. The main findings were: (1 Examination of spectral indicators within individual exercise periods of the test showed that neither Fmean nor Fmedian decreased significantly during the last (most fatiguing exercise periods. (2 Examination of the whole incremental test showed that the behaviour of Fmean and Fmedian with increasing power output was highly inconsistent and varied greatly among subjects. (3 Over the whole incremental test, half of the participants exhibited a positive relation between spectral indicators and workload, whereas the other half demonstrated the opposite behavior. Collectively, these findings indicate that spectral sEMG indexes do not provide a reliable measure of the fatigue state of the muscle during an incremental cycling test. Moreover, it is concluded that it is not possible to determine the onset of neuromuscular fatigue during an incremental cycling test by examining spectral indicators within individual exercise periods of the test.

  17. Analysis of sEMG signals using discrete wavelet transform for muscle fatigue detection

    Science.gov (United States)

    Flórez-Prias, L. A.; Contreras-Ortiz, S. H.

    2017-11-01

    The purpose of the present article is to characterize sEMG signals to determine muscular fatigue levels. To do this, the signal is decomposed using the discrete wavelet transform, which offers noise filtering features, simplicity and efficiency. sEMG signals on the forearm were acquired and analyzed during the execution of cyclic muscular contractions in the presence and absence of fatigue. When the muscle fatigues, the sEMG signal shows a more erratic behavior of the signal as more energy is required to maintain the effort levels.

  18. Estimation of continuous thumb angle and force using electromyogram classification

    Directory of Open Access Journals (Sweden)

    Abdul Rahman Siddiqi

    2016-09-01

    Full Text Available Human hand functions range from precise minute handling to heavy and robust movements. Remarkably, 50% of all hand functions are made possible by the thumb. Therefore, developing an artificial thumb that can mimic the actions of a real thumb precisely is a major achievement. Despite many efforts dedicated to this area of research, control of artificial thumb movements in resemblance to our natural movement still poses as a challenge. Most of the development in this area is based on discontinuous thumb position control, which makes it possible to recreate several of the most important functions of the thumb but does not result in total imitation. This work looks into the classification of electromyogram signals from thumb muscles for the prediction of thumb angle and force during flexion motion. For this purpose, an experimental setup is developed to measure the thumb angle and force throughout the range of flexion and simultaneously gather the electromyogram signals. Further, various features are extracted from these signals for classification and the most suitable feature set is determined and applied to different classifiers. A “piecewise discretization” approach is used for continuous angle prediction. Breaking away from previous research studies, the frequency-domain features performed better than the time-domain features, with the best feature combination turning out to be median frequency–mean frequency–mean power. As for the classifiers, the support vector machine proved to be the most accurate classifier giving about 70% accuracy for both angle and force classification and close to 50% for joint angle–force classification.

  19. Comparison between sEMG and force as control interfaces to support planar arm movements in adults with Duchenne: a feasibility study.

    Science.gov (United States)

    Lobo-Prat, Joan; Nizamis, Kostas; Janssen, Mariska M H P; Keemink, Arvid Q L; Veltink, Peter H; Koopman, Bart F J M; Stienen, Arno H A

    2017-07-12

    Adults with Duchenne muscular dystrophy (DMD) can benefit from devices that actively support their arm function. A critical component of such devices is the control interface as it is responsible for the human-machine interaction. Our previous work indicated that surface electromyography (sEMG) and force-based control with active gravity and joint-stiffness compensation were feasible solutions for the support of elbow movements (one degree of freedom). In this paper, we extend the evaluation of sEMG- and force-based control interfaces to simultaneous and proportional control of planar arm movements (two degrees of freedom). Three men with DMD (18-23 years-old) with different levels of arm function (i.e. Brooke scores of 4, 5 and 6) performed a series of line-tracing tasks over a tabletop surface using an experimental active arm support. The arm movements were controlled using three control methods: sEMG-based control, force-based control with stiffness compensation (FSC), and force-based control with no compensation (FNC). The movement performance was evaluated in terms of percentage of task completion, tracing error, smoothness and speed. For subject S1 (Brooke 4) FNC was the preferred method and performed better than FSC and sEMG. FNC was not usable for subject S2 (Brooke 5) and S3 (Brooke 6). Subject S2 presented significantly lower movement speed with sEMG than with FSC, yet he preferred sEMG since FSC was perceived to be too fatiguing. Subject S3 could not successfully use neither of the two force-based control methods, while with sEMG he could reach almost his entire workspace. Movement performance and subjective preference of the three control methods differed with the level of arm function of the participants. Our results indicate that all three control methods have to be considered in real applications, as they present complementary advantages and disadvantages. The fact that the two weaker subjects (S2 and S3) experienced the force-based control

  20. Novel Feature Modelling the Prediction and Detection of sEMG Muscle Fatigue towards an Automated Wearable System

    Directory of Open Access Journals (Sweden)

    Mohamed R. Al-Mulla

    2010-05-01

    Full Text Available Surface Electromyography (sEMG activity of the biceps muscle was recorded from ten subjects performing isometric contraction until fatigue. A novel feature (1D spectro_std was used to extract the feature that modeled three classes of fatigue, which enabled the prediction and detection of fatigue. Initial results of class separation were encouraging, discriminating between the three classes of fatigue, a longitudinal classification on Non-Fatigue and Transition-to-Fatigue shows 81.58% correct classification with accuracy 0.74 of correct predictions while the longitudinal classification on Transition-to-Fatigue and Fatigue showed lower average correct classification of 66.51% with a positive classification accuracy 0.73 of correct prediction. Comparison of the 1D spectro_std with other sEMG fatigue features on the same dataset show a significant improvement in classification, where results show a significant 20.58% (p < 0.01 improvement when using the 1D spectro_std to classify Non-Fatigue and Transition-to-Fatigue. In classifying Transition-to-Fatigue and Fatigue results also show a significant improvement over the other features giving 8.14% (p < 0.05 on average of all compared features.

  1. Normalization of electromyogram in the neck-shoulder region.

    Science.gov (United States)

    Nieminen, H; Takala, E P; Viikari-Juntura, E

    1993-01-01

    Linear and curvilinear electromyogram (EMG) normalization methods were compared among ten healthy men during a simulated work cycle demanding attention and static holding of the arm ('Solitaire test'). Maximal voluntary contractions (MVC) and gradually increasing contractions up to 70% of MVC were used for normalization in different arm postures. The test contractions studied included inward and outward rotations, abduction, shoulder elevation, and flexion in different arm positions. The shoulder load moment was calculated for the flexion tests using a simple two-dimensional model. The effect of arm posture on the EMG versus shoulder load moment relationship was studied on the following muscles: supraspinatus, infraspinatus, trapezius (three parts), deltoid (two parts) and pectoralis major. All muscles participated in the MVC tests performed, and its was not possible to suggest a single recommended test for each muscle. Differences in normalized EMG median values ranging up to 30% of MVC were found between linear and curvilinear normalization methods. Short-term repeatability of normalization based on a contraction with gradually increasing force was good. Arm posture affected the relationships between shoulder load moment and EMG activity of all muscles studied. Arm posture did not, however, have a significant effect on the estimated amplitude probability distribution functions during the simulated work task. Therefore, at least for the tasks studied, the principle of normalizing in the middle position of the range of movement was deemed acceptable.

  2. Using gastrocnemius sEMG and plasma α-synuclein for the prediction of freezing of gait in Parkinson's disease patients.

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    Xiao-Ying Wang

    Full Text Available Freezing of gait (FOG is a complicated gait disturbance in Parkinson's disease (PD and a relevant subclinical predictor algorithm is lacking. The main purpose of this study is to explore the potential value of surface electromyograph (sEMG and plasma α-synuclein levels as predictors of the FOG seen in PD. 21 PD patients and 15 normal controls were recruited. Motor function was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS and Freezing of gait questionnaire (FOG-Q. Simultaneously, gait analysis was also performed using VICON capture system in PD patients and sEMG data was recorded as well. Total plasma α-synuclein was quantitatively assessed by Luminex assay in all participants. Recruited PD patients were classified into two groups: PD patients with FOG (PD+FOG and without FOG (PD-FOG, based on clinical manifestation, the results of the FOG-Q and VICON capture system. PD+FOG patients displayed higher FOG-Q scores, decreased walking speed, smaller step length, smaller stride length and prolonged double support time compared to the PD-FOG in the gait trial. sEMG data indicated that gastrocnemius activity in PD+FOG patients was significantly reduced compared to PD-FOG patients. In addition, plasma α-synuclein levels were significantly decreased in the PD+FOG group compared to control group; however, no significant difference was found between the PD+FOG and PD-FOG groups. Our study revealed that gastrocnemius sEMG could be used to evaluate freezing gait in PD patients, while plasma α-synuclein might discriminate freezing of gait in PD patients from normal control, though no difference was found between the PD+FOG and PD-FOG groups.

  3. Learning to modulate the partial powers of a single sEMG power spectrum through a novel human-computer interface.

    Science.gov (United States)

    Skavhaug, Ida-Maria; Lyons, Kenneth R; Nemchuk, Anna; Muroff, Shira D; Joshi, Sanjay S

    2016-06-01

    New human-computer interfaces that use bioelectrical signals as input are allowing study of the flexibility of the human neuromuscular system. We have developed a myoelectric human-computer interface which enables users to navigate a cursor to targets through manipulations of partial powers within a single surface electromyography (sEMG) signal. Users obtain two-dimensional control through simultaneous adjustments of powers in two frequency bands within the sEMG spectrum, creating power profiles corresponding to cursor positions. It is unlikely that these types of bioelectrical manipulations are required during routine muscle contractions. Here, we formally establish the neuromuscular ability to voluntarily modulate single-site sEMG power profiles in a group of naïve subjects under restricted and controlled conditions using a wrist muscle. All subjects used the same pre-selected frequency bands for control and underwent the same training, allowing a description of the average learning progress throughout eight sessions. We show that subjects steadily increased target hit rates from 48% to 71% and exhibited greater control of the cursor's trajectories following practice. Our results point towards an adaptable neuromuscular skill, which may allow humans to utilize single muscle sites as limited general-purpose signal generators. Ultimately, the goal is to translate this neuromuscular ability to practical interfaces for the disabled by using a spared muscle to control external machines. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. A soft robotic exomusculature glove with integrated sEMG sensing for hand rehabilitation.

    Science.gov (United States)

    Delph, Michael A; Fischer, Sarah A; Gauthier, Phillip W; Luna, Carlos H Martinez; Clancy, Edward A; Fischer, Gregory S

    2013-06-01

    Stroke affects 750,000 people annually, and 80% of stroke survivors are left with weakened limbs and hands. Repetitive hand movement is often used as a rehabilitation technique in order to regain hand movement and strength. In order to facilitate this rehabilitation, a robotic glove was designed to aid in the movement and coordination of gripping exercises. This glove utilizes a cable system to open and close a patients hand. The cables are actuated by servomotors, mounted in a backpack weighing 13.2 lbs including battery power sources. The glove can be controlled in terms of finger position and grip force through switch interface, software program, or surface myoelectric (sEMG) signal. The primary control modes of the system provide: active assistance, active resistance and a preprogrammed mode. This project developed a working prototype of the rehabilitative robotic glove which actuates the fingers over a full range of motion across one degree-of-freedom, and is capable of generating a maximum 15N grip force.

  5. Detecting and Predicting Muscle Fatigue during Typing By SEMG Signal Processing and Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Elham Ghoochani

    2011-03-01

    Full Text Available Introduction: Repetitive strain injuries are one of the most prevalent problems in occupational diseases. Repetition, vibration and bad postures of the extremities are physical risk factors related to work that can cause chronic musculoskeletal disorders. Repetitive work on a computer with low level contraction requires the posture to be maintained for a long time, which can cause muscle fatigue. Muscle fatigue in shoulders and neck is one of the most prevalent problems reported with computer users especially during typing. Surface electromyography (SEMG signals are used for detecting muscle fatigue as a non-invasive method. Material and Methods: Nine healthy females volunteered for signal recoding during typing. EMG signals were recorded from the trapezius muscle, which is subjected to muscle fatigue during typing.  After signal analysis and feature extraction, detecting and predicting muscle fatigue was performed by using the MLP artificial neural network. Results: Recorded signals were analyzed in time and frequency domains for feature extraction. Results of classification showed that the MLP neural network can detect and predict muscle fatigue during typing with 80.79 % ± 1.04% accuracy. Conclusion: Intelligent classification and prediction of muscle fatigue can have many applications in human factors engineering (ergonomics, rehabilitation engineering and biofeedback equipment for mitigating the injuries of repetitive works.

  6. Study of the SEMG probability distribution of the paretic tibialis anterior muscle

    International Nuclear Information System (INIS)

    Cherniz, AnalIa S; Bonell, Claudia E; Tabernig, Carolina B

    2007-01-01

    The surface electromyographic signal is a stochastic signal that has been modeled as a Gaussian process, with a zero mean. It has been experimentally proved that this probability distribution can be adjusted with less error to a Laplacian type distribution. The selection of estimators for the detection of changes in the amplitude of the muscular signal depends, among other things, on the type of distribution. In the case of subjects with lesions to the superior motor neuron, the lack of central control affects the muscular tone, the force and the patterns of muscular movement involved in activities such as the gait cycle. In this work, the distribution types of the SEMG signal amplitudes of the tibialis anterior muscle are evaluated during gait, both in two healthy subjects and in two hemiparetic ones in order to select the estimators that best characterize them. It was observed that the Laplacian distribution function would be the one that best adjusts to the experimental data in the studied subjects, although this largely depends on the subject and on the data segment analyzed

  7. Electromyogram refinement using muscle synergy based regulation of uncertain information.

    Science.gov (United States)

    Min, Kyuengbo; Shin, Duk; Lee, Jongho; Kakei, Shinji

    2018-04-27

    Electromyogram signal (EMG) measurement frequently experiences uncertainty attributed to issues caused by technical constraints such as cross talk and maximum voluntary contraction. Due to these problems, individual EMGs exhibit uncertainty in representing their corresponding muscle activations. To regulate this uncertainty, we proposed an EMG refinement, which refines EMGs with regulating the contribution redundancy of the signals from EMGs to approximating torques through EMG-driven torque estimation (EDTE) using the muscular skeletal forward dynamic model. To regulate this redundancy, we must consider the synergistic contribution redundancy of muscles, including "unmeasured" muscles, to approximating torques, which primarily causes redundancy of EDTE. To suppress this redundancy, we used the concept of muscle synergy, which is a key concept of analyzing the neurophysiological regulation of contribution redundancy of muscles to exerting torques. Based on this concept, we designed a muscle-synergy-based EDTE as a framework for EMG refinement, which regulates the abovementioned uncertainty of individual EMGs in consideration of unmeasured muscles. In achieving the proposed EMG refinement, the most considerable point is to suppress a large change such as overestimation attributed to enhancement of the contribution of particular muscles to estimating torques. Therefore it is reasonable to refine EMGs by minimizing the change in EMGs. To evaluate this model, we used a Bland-Altman plot, which quantitatively evaluates the proportional bias of refined signals to EMGs. Through this evaluation, we showed that the proposed EDTE minimizes the bias while approximating torques. Therefore this minimization optimally regulates the uncertainty of EMGs and thereby leads to optimal EMG refinement. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Evaluation of localized muscle fatigue using power spectral density analysis of the electromyogram

    Science.gov (United States)

    Lafevers, E. V.

    1974-01-01

    Surface electromyograms (EMGs) taken from three upper torso muscles during a push-pull task were analyzed by a power spectral density technique to determine the operational feasibility of the technique for identifying changes in the EMGs resulting from muscular fatigue. The EMGs were taken from four subjects under two conditions (1) in shirtsleeves and (2) in a pressurized space suit. This study confirmed that frequency analysis of dynamic muscle activity is capable of providing reliable data for many industrial applications where fatigue may be of practical interest. The results showed significant effects of the pressurized space suit on the pattern of shirtsleeve fatigue responses of the muscles. The data also revealed (1) reliable differences between muscles in fatigue-induced responses to various locations in the reach envelope at which the subjects were required to perform the push-pull exercise and (2) the differential sensitivity of muscles to the various reach positions in terms of fatigue-related shifts in EMG power.

  9. Short time Fourier analysis of the electromyogram - Fast movements and constant contraction

    Science.gov (United States)

    Hannaford, Blake; Lehman, Steven

    1986-01-01

    Short-time Fourier analysis was applied to surface electromyograms (EMG) recorded during rapid movements, and during isometric contractions at constant forces. A portion of the data to be transformed by multiplying the signal by a Hamming window was selected, and then the discrete Fourier transform was computed. Shifting the window along the data record, a new spectrum was computed each 10 ms. The transformed data were displayed in spectograms or 'voiceprints'. This short-time technique made it possible to see time-dependencies in the EMG that are normally averaged in the Fourier analysis of these signals. Spectra of EMGs during isometric contractions at constant force vary in the short (10-20 ms) term. Short-time spectra from EMGs recorded during rapid movements were much less variable. The windowing technique picked out the typical 'three-burst pattern' in EMG's from both wrist and head movements. Spectra during the bursts were more consistent than those during isometric contractions. Furthermore, there was a consistent shift in spectral statistics in the course of the three bursts. Both the center frequency and the variance of the spectral energy distribution grew from the first burst to the second burst in the same muscle. The analogy between EMGs and speech signals is extended to argue for future applicability of short-time spectral analysis of EMG.

  10. Curved Microneedle Array-Based sEMG Electrode for Robust Long-Term Measurements and High Selectivity

    Directory of Open Access Journals (Sweden)

    Minjae Kim

    2015-07-01

    Full Text Available Surface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a flexible band-integrated, curved microneedle array electrode for robust long-term measurements, high selectivity, and easy applicability. Signal quality, in terms of long-term usability and sensitivity to perspiration, was investigated. Its motion-discriminating performance was also evaluated. The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h. The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode.

  11. Simulation of facial expressions using person-specific sEMG signals controlling a biomechanical face model.

    Science.gov (United States)

    Eskes, Merijn; Balm, Alfons J M; van Alphen, Maarten J A; Smeele, Ludi E; Stavness, Ian; van der Heijden, Ferdinand

    2018-01-01

    Functional inoperability in advanced oral cancer is difficult to assess preoperatively. To assess functions of lips and tongue, biomechanical models are required. Apart from adjusting generic models to individual anatomy, muscle activation patterns (MAPs) driving patient-specific functional movements are necessary to predict remaining functional outcome. We aim to evaluate how volunteer-specific MAPs derived from surface electromyographic (sEMG) signals control a biomechanical face model. Muscle activity of seven facial muscles in six volunteers was measured bilaterally with sEMG. A triple camera set-up recorded 3D lip movement. The generic face model in ArtiSynth was adapted to our needs. We controlled the model using the volunteer-specific MAPs. Three activation strategies were tested: activating all muscles [Formula: see text], selecting the three muscles showing highest muscle activity bilaterally [Formula: see text]-this was calculated by taking the mean of left and right muscles and then selecting the three with highest variance-and activating the muscles considered most relevant per instruction [Formula: see text], bilaterally. The model's lip movement was compared to the actual lip movement performed by the volunteers, using 3D correlation coefficients [Formula: see text]. The correlation coefficient between simulations and measurements with [Formula: see text] resulted in a median [Formula: see text] of 0.77. [Formula: see text] had a median [Formula: see text] of 0.78, whereas with [Formula: see text] the median [Formula: see text] decreased to 0.45. We demonstrated that MAPs derived from noninvasive sEMG measurements can control movement of the lips in a generic finite element face model with a median [Formula: see text] of 0.78. Ultimately, this is important to show the patient-specific residual movement using the patient's own MAPs. When the required treatment tools and personalisation techniques for geometry and anatomy become available, this may

  12. Repeatability of grasp recognition for robotic hand prosthesis control based on sEMG data.

    Science.gov (United States)

    Palermo, Francesca; Cognolato, Matteo; Gijsberts, Arjan; Muller, Henning; Caputo, Barbara; Atzori, Manfredo

    2017-07-01

    Control methods based on sEMG obtained promising results for hand prosthetics. Control system robustness is still often inadequate and does not allow the amputees to perform a large number of movements useful for everyday life. Only few studies analyzed the repeatability of sEMG classification of hand grasps. The main goals of this paper are to explore repeatability in sEMG data and to release a repeatability database with the recorded experiments. The data are recorded from 10 intact subjects repeating 7 grasps 12 times, twice a day for 5 days. The data are publicly available on the Ninapro web page. The analysis for the repeatability is based on the comparison of movement classification accuracy in several data acquisitions and for different subjects. The analysis is performed using mean absolute value and waveform length features and a Random Forest classifier. The accuracy obtained by training and testing on acquisitions at different times is on average 27.03% lower than training and testing on the same acquisition. The results obtained by training and testing on different acquisitions suggest that previous acquisitions can be used to train the classification algorithms. The inter-subject variability is remarkable, suggesting that specific characteristics of the subjects can affect repeatibility and sEMG classification accuracy. In conclusion, the results of this paper can contribute to develop more robust control systems for hand prostheses, while the presented data allows researchers to test repeatability in further analyses.

  13. Heart rate variability and surface electromyography of trained cyclists at different cadences

    Directory of Open Access Journals (Sweden)

    Bruno Saraiva

    2016-06-01

    Full Text Available The heart rate variability (HRV and surface electromyography (sEMG are important tools in the evaluation of cardiac autonomic system and neuromuscular parameters, respectively. The aim of the study was to evaluate the behavior of HRV and sEMG of the vastus lateralis in two exercise protocols on a cycle ergometer at 60 and 80 rpm. Eight healthy men cyclists who have trained for at least two years were evaluated. Reduction was observed followed by stabilization of RMSSD and SDNN indices of HRV (p<0.05 along with increases in the amplitude of the sEMG signal (p<0.05 in both protocols. Significant correlations were observed between the responses of HRV and sEMG in the cadence of 60 rpm (RMSSD and sEMG: r = -0.42, p=0.03; SDNN and sEMG: r = -0.45, p=0.01 and 80 rpm (RMSSD and sEMG: r = -0.47, p=0.02; SDNN and sEMG: r = -0.49, p=0.01, yet no difference was observed for these variables between the two protocols. We concluded that the parasympathetic cardiac responses and sEMG are independent of cadences applied at the same power output.

  14. Electromyogram median power frequency in dynamic exercise at medium exercise intensities

    NARCIS (Netherlands)

    Ament, W; Bonga, GJJ; Hof, AL; Verkerke, GJ

    The electromyogram (EMG) median power Frequency of the calf muscles was investigated during an exhausting treadmill exercise and a 20-min recovery period. The exercise was an uphill run at a speed of 5 km . h(-1) and a gradient of 20%. During exercise there was no decrease of EMG median power

  15. Nonlinear analysis of electromyogram following gait training with myoelectrically triggered neuromuscular electrical stimulation in stroke survivors

    Science.gov (United States)

    Dutta, Anirban; Khattar, Bhawna; Banerjee, Alakananda

    2012-12-01

    Neuromuscular electrical stimulation (NMES) facilitates ambulatory function after paralysis by activating the muscles of the lower extremities. The NMES-assisted stepping can either be triggered by a heel-switch (switch-trigger), or by an electromyogram (EMG)-based gait event detector (EMG-trigger). The command sources—switch-trigger or EMG-trigger—were presented to each group of six chronic (>6 months post-stroke) hemiplegic stroke survivors. The switch-trigger group underwent transcutaneous NMES-assisted gait training for 1 h, five times a week for 2 weeks, where the stimulation of the tibialis anterior muscle of the paretic limb was triggered with a heel-switch detecting heel-rise of the same limb. The EMG-trigger group underwent transcutaneous NMES-assisted gait training of the same duration and frequency where the stimulation was triggered with surface EMG from medial gastrocnemius (MG) of the paretic limb in conjunction with a heel-switch detecting heel-rise of the same limb. During the baseline and post-intervention surface EMG assessment, a total of 10 s of surface EMG was recorded from bilateral MG muscle while the subjects tried to stand steady on their toes. A nonlinear tool—recurrence quantification analysis (RQA)—was used to analyze the surface EMG. The objective of this study was to find the effect of NMES-assisted gait training with switch-trigger or EMG-trigger on two RQA parameters—the percentage of recurrence (%Rec) and determinism (%Det), which were extracted from surface EMG during fatiguing contractions of the paretic muscle. The experimental results showed that during fatiguing contractions, (1) %Rec and %Det have a higher initial value for paretic muscle than the non-paretic muscle, (2) the rate of change in %Rec and %Det was negative for the paretic muscle but positive for the non-paretic muscle, (3) the rate of change in %Rec and %Det significantly increased from baseline for the paretic muscle after EMG-triggered NMES

  16. Reproducibility of 3D kinematics and surface electromyography measurements of mastication

    NARCIS (Netherlands)

    Remijn, L.; Groen, B.E.; Speyer, R.; Limbeek, J. van; Sanden, M.W. van der

    2016-01-01

    The aim of this study was to determine the measurement reproducibility for a procedure evaluating the mastication process and to estimate the smallest detectable differences of 3D kinematic and surface electromyography (sEMG) variables. Kinematics of mandible movements and sEMG activity of the

  17. Muscle fatigue estimation with twitch force derived from sEMG peaks.

    Science.gov (United States)

    Na, Youngjin; Lee, Hae-Dong; Kim, Jung

    2015-08-01

    We propose a new method - twitch force - for estimation of the muscle behavior during voluntary contraction for assessing localized muscle fatigue. The proposed method uses the sEMG peaks as input and the measured force as output. The twitch force, which is a transfer function to generate force, was estimated during fatiguing contraction. We verified the estimated twitch force based on the measured results with electrical stimulation. The participants performed isometric little finger flexion until exhaustion. SEMG was recorded on the flexor digiti minimi brevis muscle for the proposed method and the electrical stimulation electrodes on the ulnar nerve induced involuntary contraction for reference. As the muscle fatigue level increased, the twitch peaks decreased in both methods. The proposed method can be widely used in the quantitative analysis of muscle fatigue during voluntary contraction.

  18. Virtual Control of Prosthetic Hand Based on Grasping Patterns and Estimated Force from Semg

    Directory of Open Access Journals (Sweden)

    Zhu Gao-Ke

    2016-01-01

    Full Text Available Myoelectric prosthetic hands aim to serve upper limb amputees. The myoelectric control of the hand grasp action is a kind of real-time or online method. Thus it is of great necessity to carry on a study of online prosthetic hand electrical control. In this paper, the strategy of simultaneous EMG decoding of grasping patterns and grasping force was realized by controlling a virtual multi-degree-freedom prosthetic hand and a real one-degree-freedom prosthetic hand simultaneously. The former realized the grasping patterns from the recognition of the sEMG pattern. The other implemented the grasping force from sEMG force decoding. The results show that the control method is effective and feasible.

  19. Design, Development and Testing of a Low-Cost sEMG System and Its Use in Recording Muscle Activity in Human Gait

    Directory of Open Access Journals (Sweden)

    Tamara Grujic Supuk

    2014-05-01

    Full Text Available Surface electromyography (sEMG is an important measurement technique used in biomechanical, rehabilitation and sport environments. In this article the design, development and testing of a low-cost wearable sEMG system are described. The hardware architecture consists of a two-cascade small-sized bioamplifier with a total gain of 2,000 and band-pass of 3 to 500 Hz. The sampling frequency of the system is 1,000 Hz. Since real measured EMG signals are usually corrupted by various types of noises (motion artifacts, white noise and electromagnetic noise present at 50 Hz and higher harmonics, we have tested several denoising techniques, both on artificial and measured EMG signals. Results showed that a wavelet—based technique implementing Daubechies5 wavelet and soft sqtwolog thresholding is the most appropriate for EMG signals denoising. To test the system performance, EMG activities of six dominant muscles of ten healthy subjects during gait were measured (gluteus maximus, biceps femoris, sartorius, rectus femoris, tibialis anterior and medial gastrocnemius. The obtained EMG envelopes presented against the duration of gait cycle were compared favourably with the EMG data available in the literature, suggesting that the proposed system is suitable for a wide range of applications in biomechanics.

  20. Development of a Hybrid Hands-Off Human Computer Interface Based on Electromyogram Signals and Eye-Gaze Tracking

    National Research Council Canada - National Science Library

    Lyons, E

    2001-01-01

    ...) and Electromyogram (EMG) signals is introduced. This system combines the advantages of both subsystems, providing quick cursor displacement in long excursions and steady, accurate movement in small position adjustments...

  1. INFLUENCE OF POSTURE ON THE RELATION BETWEEN SURFACE ELECTROMYOGRAM AMPLITUDE AND BACK MUSCLE MOMENT - CONSEQUENCES FOR THE USE OF SURFACE ELECTROMYOGRAM TO MEASURE BACK LOAD

    NARCIS (Netherlands)

    MOUTON, LJ; HOF, AL; DEJONGH, HJ; EISMA, WH

    1991-01-01

    The aim of the study was to analyse the effect of posture on the relation between EMG amplitude and moment of the back muscles in different subjects, in order to gain a better insight into the possibilities of EMG as a means of measuring individual back load. Eight healthy subjects participated in

  2. Comparison of algorithms to quantify muscle fatigue in upper limb muscles based on sEMG signals.

    Science.gov (United States)

    Kahl, Lorenz; Hofmann, Ulrich G

    2016-11-01

    This work compared the performance of six different fatigue detection algorithms quantifying muscle fatigue based on electromyographic signals. Surface electromyography (sEMG) was obtained by an experiment from upper arm contractions at three different load levels from twelve volunteers. Fatigue detection algorithms mean frequency (MNF), spectral moments ratio (SMR), the wavelet method WIRM1551, sample entropy (SampEn), fuzzy approximate entropy (fApEn) and recurrence quantification analysis (RQA%DET) were calculated. The resulting fatigue signals were compared considering the disturbances incorporated in fatiguing situations as well as according to the possibility to differentiate the load levels based on the fatigue signals. Furthermore we investigated the influence of the electrode locations on the fatigue detection quality and whether an optimized channel set is reasonable. The results of the MNF, SMR, WIRM1551 and fApEn algorithms fell close together. Due to the small amount of subjects in this study significant differences could not be found. In terms of disturbances the SMR algorithm showed a slight tendency to out-perform the others. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  3. Standardization of surface electromyography utilized to evaluate patients with dysphagia

    Directory of Open Access Journals (Sweden)

    Vaiman Michael

    2007-06-01

    Full Text Available Abstract Backgorund Patients suspected of having swallowing disorders, could highly benefit from simple diagnostic screening before being referred to specialist evaluations. We introduce surface electromyography (sEMG to carry out rapid assessment of such patients and propose suggestions for standardizing sEMGs in order to identify abnormal deglutition. Methods Specifics steps for establishing standards for applying the technique for screening purposes (e.g., evaluation of specific muscles, the requirements for diagnostic sEMG equipment, the sEMG technique itself, and defining the tests suitable for assessing deglutition (e.g., saliva, normal, and excessive swallows and uninterrupted drinking of water are presented in detail. A previously described normative database for single swallowing and drinking and standard approach to analysis was compared to data on the duration and electric activity of muscles involved in deglutition and with sEMG recordings in order to estimate stages of a swallow. Conclusion SEMG of swallowing is a simple and reliable method for screening and preliminary differentiation among dysphagia and odynophagia of various origins. This noninvasive radiation-free examination has a low level of discomfort, and is simple, timesaving and inexpensive to perform. With standardization of the technique and an established normative database, sEMG can serve as a reliable screening method for optimal patient management.

  4. Spontaneous mechanical and electrical activities of human calf musculature at rest assessed by repetitive single-shot diffusion-weighted MRI and simultaneous surface electromyography.

    Science.gov (United States)

    Schwartz, Martin; Steidle, Günter; Martirosian, Petros; Ramos-Murguialday, Ander; Preißl, Hubert; Stemmer, Alto; Yang, Bin; Schick, Fritz

    2018-05-01

    Assessment of temporal and spatial relations between spontaneous mechanical activities in musculature (SMAM) at rest as revealed by diffusion-weighted imaging (DWI) and electrical muscular activities in surface EMG (sEMG). Potential influences of static and radiofrequency magnetic fields on muscular activity on sEMG measurements at rest were examined systematically. Series of diffusion-weighted stimulated echo planar imaging were recorded with concurrent sEMG measurements. Electrical activities in sEMG were analyzed by non-parametric Friedman and two-sample Kolmogorov-Smirnov test. Direct correlation of both modalities was investigated by temporal mapping of electrical activity in sEMG to DWI repetition interval. Electrical activities in sEMG and number of visible SMAMs in DWI showed a strong correlation (ρ = 0.9718). High accordance between sEMG activities and visible SMAMs in DWI in a near-surface region around sEMG electrodes was achieved. Characteristics of sEMG activities were almost similar under varying magnetic field conditions. Visible SMAMs in DWI have shown a close and direct relation to concurrent signals recorded by sEMG. MR-related magnetic fields had no significant effects on findings in sEMG. Hence, appearance of SMAMs in DWI should not be considered as imaging artifact or as effects originating from the special conditions of MR examinations. Spatial and temporal distributions of SMAMs indicate characteristics of spontaneous (microscopic) mechanical muscular action at rest. Therefore, DWI techniques should be considered as non-invasive tools for studying physiology and pathophysiology of spontaneous activities in resting muscle. Magn Reson Med 79:2784-2794, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  5. Enhanced hybrid electromyogram/Eye Gaze Tracking cursor control system for hands-free computer interaction.

    Science.gov (United States)

    Chin, Craig A; Barreto, Armando

    2006-01-01

    This paper outlines the development and initial testing of a new hybrid computer cursor control system based on Eye Gaze Tracking (EGT) and electromyogram (EMG) processing for hands-free control of the computer cursor. The ultimate goal of the system is to provide an efficient computer interaction mechanism for individuals with severe motor disabilities (or specialized operators whose hands are committed to other tasks, such as surgeons, pilots, etc.) The paper emphasizes the enhancements that have been made on different areas of the architecture, with respect to a previous prototype developed by our group, and demonstrates the performance improvement verified for some of the enhancements.

  6. Real-time intelligent pattern recognition algorithm for surface EMG signals

    Directory of Open Access Journals (Sweden)

    Jahed Mehran

    2007-12-01

    Full Text Available Abstract Background Electromyography (EMG is the study of muscle function through the inquiry of electrical signals that the muscles emanate. EMG signals collected from the surface of the skin (Surface Electromyogram: sEMG can be used in different applications such as recognizing musculoskeletal neural based patterns intercepted for hand prosthesis movements. Current systems designed for controlling the prosthetic hands either have limited functions or can only be used to perform simple movements or use excessive amount of electrodes in order to achieve acceptable results. In an attempt to overcome these problems we have proposed an intelligent system to recognize hand movements and have provided a user assessment routine to evaluate the correctness of executed movements. Methods We propose to use an intelligent approach based on adaptive neuro-fuzzy inference system (ANFIS integrated with a real-time learning scheme to identify hand motion commands. For this purpose and to consider the effect of user evaluation on recognizing hand movements, vision feedback is applied to increase the capability of our system. By using this scheme the user may assess the correctness of the performed hand movement. In this work a hybrid method for training fuzzy system, consisting of back-propagation (BP and least mean square (LMS is utilized. Also in order to optimize the number of fuzzy rules, a subtractive clustering algorithm has been developed. To design an effective system, we consider a conventional scheme of EMG pattern recognition system. To design this system we propose to use two different sets of EMG features, namely time domain (TD and time-frequency representation (TFR. Also in order to decrease the undesirable effects of the dimension of these feature sets, principle component analysis (PCA is utilized. Results In this study, the myoelectric signals considered for classification consists of six unique hand movements. Features chosen for EMG signal

  7. Neuromuscular functions in sportsmen and fibromyalgia patients : a surface EMG study in static and dynamic conditions

    NARCIS (Netherlands)

    Klaver-Krol, E.G.

    2012-01-01

    This thesis presents two studies, one involving sportsmen (sprinters versus endurance athletes) and one fibromyalgia patients (patients versus healthy controls). The studies have investigated muscular functions using a non-invasive method: surface electromyography (sEMG). In the sportsmen,

  8. Power spectral density analysis of the electromyogram from a work task performed in a full pressure suit. Ph.D. Thesis - Houston Univ.; [for determining muscular fatigue

    Science.gov (United States)

    Lafevers, E. V.

    1974-01-01

    Surface electromyograms (EMG) taken from three upper torso muscles during a push-pull task were analyzed by a power spectral density technique to determine the utility of the spectral analysis for identifying changes in the EMG caused by muscular fatigue. The results confirmed the value of the frequency analysis for identifying fatigue producing muscular performance. Data revealed reliable differences between muscles in fatigue induced responses to various locations in the reach envelope at which the subjects were required to perform the push-pull exercise, and the differential sensitivity of individual muscles to the various reach positions; i.e., certain reach positions imposed more fatigue related shifts in EMG power than did others. It was found that a pressurized space suit changed the pattern of normal shirtsleeve muscle fatigue responses in all three of the muscles.

  9. Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises.

    Science.gov (United States)

    Ebenbichler, Gerold R; Unterlerchner, Lena; Habenicht, Richard; Bonato, Paolo; Kollmitzer, Josef; Mair, Patrick; Riegler, Sara; Kienbacher, Thomas

    2017-01-01

    Purpose: To investigate the differences in neural control of back muscles activated during the eccentric vs. the concentric portions of a cyclic, submaximal, fatiguing trunk extension exercise via the analysis of amplitude and time-frequency parameters derived from surface electromyographic (SEMG) data. Methods: Using back dynamometers, 87 healthy volunteers performed three maximum voluntary isometric trunk extensions (MVC's), an isometric trunk extension at 80% MVC, and 25 cyclic, dynamic trunk extensions at 50% MVC. Dynamic testing was performed with the trunk angular displacement ranging from 0° to 40° and the trunk angular velocity set at 20°/s. SEMG data was recorded bilaterally from the iliocostalis lumborum at L1, the longissimus dorsi at L2, and the multifidus muscles at L5. The initial value and slope of the root mean square (RMS-SEMG) and the instantaneous median frequency (IMDF-SEMG) estimates derived from the SEMG recorded during each exercise cycle were used to investigate the differences in MU control marking the eccentric vs. the concentric portions of the exercise. Results: During the concentric portions of the exercise, the initial RMS-SEMG values were almost twice those observed during the eccentric portions of the exercise. The RMS-SEMG values generally increased during the concentric portions of the exercise while they mostly remained unchanged during the eccentric portions of the exercise with significant differences between contraction types. Neither the initial IMDF-SEMG values nor the time-course of the IMDF-SEMG values significantly differed between the eccentric and the concentric portions of the exercise. Conclusions: The comparison of the investigated SEMG parameters revealed distinct neural control strategies during the eccentric vs. the concentric portions of the cyclic exercise. We explain these differences by relying upon the principles of orderly recruitment and common drive governing motor unit behavior.

  10. Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises

    Directory of Open Access Journals (Sweden)

    Gerold R. Ebenbichler

    2017-05-01

    Full Text Available Purpose: To investigate the differences in neural control of back muscles activated during the eccentric vs. the concentric portions of a cyclic, submaximal, fatiguing trunk extension exercise via the analysis of amplitude and time-frequency parameters derived from surface electromyographic (SEMG data.Methods: Using back dynamometers, 87 healthy volunteers performed three maximum voluntary isometric trunk extensions (MVC's, an isometric trunk extension at 80% MVC, and 25 cyclic, dynamic trunk extensions at 50% MVC. Dynamic testing was performed with the trunk angular displacement ranging from 0° to 40° and the trunk angular velocity set at 20°/s. SEMG data was recorded bilaterally from the iliocostalis lumborum at L1, the longissimus dorsi at L2, and the multifidus muscles at L5. The initial value and slope of the root mean square (RMS-SEMG and the instantaneous median frequency (IMDF-SEMG estimates derived from the SEMG recorded during each exercise cycle were used to investigate the differences in MU control marking the eccentric vs. the concentric portions of the exercise.Results: During the concentric portions of the exercise, the initial RMS-SEMG values were almost twice those observed during the eccentric portions of the exercise. The RMS-SEMG values generally increased during the concentric portions of the exercise while they mostly remained unchanged during the eccentric portions of the exercise with significant differences between contraction types. Neither the initial IMDF-SEMG values nor the time-course of the IMDF-SEMG values significantly differed between the eccentric and the concentric portions of the exercise.Conclusions: The comparison of the investigated SEMG parameters revealed distinct neural control strategies during the eccentric vs. the concentric portions of the cyclic exercise. We explain these differences by relying upon the principles of orderly recruitment and common drive governing motor unit behavior.

  11. Internet based gripper teleoperation with random time delay by using haptic feedback and SEMG

    Science.gov (United States)

    Xu, Xiaonong; Song, Aiguo; Zhang, Huatao; Ji, Peng

    2016-10-01

    Random time delay may cause instability in the internet based teleoperation system. Transparency and intuitiveness are also very important for operator to control the system to accurately perform the desired action, especially for the gripper teleoperation system. This paper presents a new grip force control method of gripper teleoperation system with haptic feedback. The system employs the SEMG signal as the control parameter in order to enhance the intuitive control experience for operator. In order to eliminate the impacts on the system stability caused by random time delay, a non-time based teleoperation method is applied to the control process. Besides, neural network and designed fuzzy logic controller is also utilized to improve this control method. The effectiveness of the proposed method is demonstrated by experiment results.

  12. Features interference electromyogram rectus femoris for skilled players in the context of special exercises

    Directory of Open Access Journals (Sweden)

    Sirenko P.O.

    2013-08-01

    Full Text Available The problems of improving physical fitness skilled players. The aim of the study is to determine the optimal position of the hip angle to the vertical plane for the manifestation of a maximum of bioelectric activity of the rectus femoris. In the experiment involved 15 players of FC "Metalist" (age 18 - 30 years. Has electromyogram muscle activity "hip flexion standing" on the mechanical simulator. Athletes performed around the maximum contraction of the muscle (musculus rectus femoris for 5 seconds. Found that the angle of 70 degrees has minimal background for developing muscular force. It is established that the position of the straight leg on the same vertical axis with the body is the position of the largest overlap actinomyosinic filaments in muscle sarcomere.

  13. Radio-transmitted electromyogram signals as indicators of swimming speed in lake trout and brown trout

    DEFF Research Database (Denmark)

    Thorstad, E.B.; Økland, F.; Koed, Anders

    2000-01-01

    Swimming speed and average electromyogram (EMG) pulse intervals were highly correlated in individual lake trout Salvelinus namaycush (r(2)=0.52-0.89) and brown trout Salmo trutta (r(2)=0.45-0.96). High correlations were found also for pooled data in both lake trout (r(2)=0.90) and brown trout...... of the Ema stock (r(2)=0.96) and Laerdal stock (r(2)=0.96). The linear relationship between swimming speed and average EMG pulse intervals differed significantly among lake trout and the brown trout stocks. This successful calibration of EMGs to swimming speed opens the possibility of recording swimming...... speed of free swimming lake trout and brown trout in situ. EMGs can also be calibrated to oxygen consumption to record energy expenditure. (C) 2000 The Fisheries Society of the British Isles...

  14. Effect of electrocardiographic contamination on surface electromyography assessment of back muscles.

    Science.gov (United States)

    Hu, Yong; Mak, Joseph N F; Luk, Keith D K

    2009-02-01

    The purpose of this study was to demonstrate the relative effect of electrocardiography (ECG) on back muscle surface electromyography (SEMG) parameters and their corresponding sensitivity in low back pain (LBP) assessment. Back muscle SEMG activities were recorded from 17 healthy subjects and 18 chronic LBP patients under static postures (straight sitting and upright standing), and dynamic action (flexion-extension). ECG cancellation based on independent component analysis (ICA) method was performed. Root mean square (RMS) and median frequency (MF) of raw and denoised SEMG data were computed respectively. Multiple comparisons were then performed. A consistent trend of change (increased MF and decreased RMS) followed ECG removal was noticed. In particular, in SEMG measurements under static postures, a significant decrease in RMS (pcorruption by ECG artifacts on SEMG measurements was found to be more serious and prominent in static postures than that in dynamic action. After ECG removal, significant improvements in the ability of SEMG to discriminate LBP patients from healthy subjects were seen in RMS amplitude recorded while standing (peffect of ECG contamination on back muscles SEMG parameters and LBP assessment.

  15. Predicting 3D lip shapes using facial surface EMG.

    Directory of Open Access Journals (Sweden)

    Merijn Eskes

    Full Text Available The aim of this study is to prove that facial surface electromyography (sEMG conveys sufficient information to predict 3D lip shapes. High sEMG predictive accuracy implies we could train a neural control model for activation of biomechanical models by simultaneously recording sEMG signals and their associated motions.With a stereo camera set-up, we recorded 3D lip shapes and simultaneously performed sEMG measurements of the facial muscles, applying principal component analysis (PCA and a modified general regression neural network (GRNN to link the sEMG measurements to 3D lip shapes. To test reproducibility, we conducted our experiment on five volunteers, evaluating several sEMG features and window lengths in unipolar and bipolar configurations in search of the optimal settings for facial sEMG.The errors of the two methods were comparable. We managed to predict 3D lip shapes with a mean accuracy of 2.76 mm when using the PCA method and 2.78 mm when using modified GRNN. Whereas performance improved with shorter window lengths, feature type and configuration had little influence.

  16. The sEMG characteristics of the low back muscles during aerobic cycling.

    Science.gov (United States)

    Xiao, Jinzhuang; Gao, Junmin; Wang, Hongrui; Yang, Xincai

    2014-01-01

    More and more people suffer from lumbar muscle strain due to lack of exercise. Cycling serves as both a stylish model of fitness and a training method in exercise and rehabilitation. A few of previous studies have examined the changes in lower extremity muscle activities during indoor cycling, but fewer data pertain to the low back muscles. This study aims to analyze the functional status of erector spinae during cycling by learning the regularity and characteristics of changes in sEMG frequency domain index-mean frequency (MF) within ten minutes. The statistical results showed that the values of 70% subjects fluctuated within the range of (0.04688 ± 0.00125) Hz within the first 30 s and the values raised rapidly to the (150 ± 10) Hz range after the 30 s. Moreover, the values trended to decline slowly in a fluctuating way after a while. However, no obvious regularity was observed among the remaining 30% of the subjects. Results of this study demonstrated that the muscle fatigue with a smaller level of low back began to emerge gradually after 30 s. Moreover, it is evident that cycling can be an incentive to the low back muscles in most people.

  17. Estimation of muscle fatigue using surface electromyography and near-infrared spectroscopy.

    Science.gov (United States)

    Taelman, Joachim; Vanderhaegen, Joke; Robijns, Mieke; Naulaers, Gunnar; Spaepen, Arthur; Van Huffel, Sabine

    2011-01-01

    This study looks at various parameters, derived from surface electromyography (sEMG) and Near Infrared Spectroscopy (NIRS) and their relationship in muscle fatigue during a static elbow flexion until exhaustion as well as during a semidynamic exercise.We found a linear increasing trend for a corrected amplitude parameter and a linear decreasing slope for the frequency content of the sEMG signal. The tissue oxygenation index (TOI) extracted from NIRS recordings showed a four-phase response for all the subjects. A strong correlation between frequency content of the sEMG signal and TOI was established. We can conclude that both sEMG and NIRS give complementary information concerning muscle fatigue.

  18. Restoration of continence following rectopexy for rectal prolapse and recovery of the internal anal sphincter electromyogram.

    Science.gov (United States)

    Farouk, R; Duthie, G S; Bartolo, D C; MacGregor, A B

    1992-05-01

    Twenty-two patients with full-thickness rectal prolapse underwent ambulatory fine wire electromyography of the internal and sphincter (IAS), external and sphincter and puborectalis, together with anorectal manometry, using a computerized system. Examinations were performed both before and 3 to 4 months after rectopexy. The median (interquartile range (i.q.r.)) preoperative IAS electromyogram (EMG) frequency was 0.18 (0.05-0.31) Hz and the median (i.q.r.) preoperative resting anal pressure was 28 (15-64) cmH2O. An improvement in the IAS EMG frequency, median (i.q.r.) 0.29 (0.19-0.38) Hz (P less than 0.03), and resting anal pressure, median (i.q.r.) 41 (20-72) cmH2O (P less than 0.05), was recorded after operation, but these variables remained significantly lower than those found in normal controls: median (i.q.r.) IAS EMG frequency 0.44 (0.36-0.48) Hz and median (i.q.r.) resting anal pressure 92 (74-98) cmH2O. We suggest that repair of the prolapse allows the IAS to recover by removing the cause of persistent rectoanal inhibition.

  19. Uterine electromyogram database and processing function interface: An open standard analysis platform for electrohysterogram signals.

    Science.gov (United States)

    Terrien, Jérémy; Marque, Catherine; Gondry, Jean; Steingrimsdottir, Thora; Karlsson, Brynjar

    2010-02-01

    The uterine electromyogram or electrohysterogram (EHG) is one of the most promising biophysical markers of preterm labor. At this time no recording parameter standard exists for EHG recordings which can be a problem for the establishment of international multicentric trials. In this paper, we present a management and processing system dedicated to storing and processing EHG signals. This system can process EHG signals recorded in different experimental conditions i.e. different sampling frequencies. The signal management is performed using an easy to use graphical user interface. Other available functions include visualization, preprocessing and analysis of EHG signals. The proposed processing functions provide temporal, spectral and time-scale parameters obtained from the EHG bibliography. The obtained results from real signals recorded in two different hospitals in two different countries are in accordance with the literature and demonstrate the potential of the proposed system. The incorporation of new functions is easy, due to a standardization of the EHG data formats. 2009 Elsevier Ltd. All rights reserved.

  20. Development of a Compact Wireless Laplacian Electrode Module for Electromyograms and Its Human Interface Applications

    Directory of Open Access Journals (Sweden)

    Akira Ichikawa

    2013-02-01

    Full Text Available In this study, we developed a compact wireless Laplacian electrode module for electromyograms (EMGs. One of the advantages of the Laplacian electrode configuration is that EMGs obtained with it are expected to be sensitive to the firing of the muscle directly beneath the measurement site. The performance of the developed electrode module was investigated in two human interface applications: character-input interface and detection of finger movement during finger Braille typing. In the former application, the electrode module was combined with an EMG-mouse click converter circuit. In the latter, four electrode modules were used for detection of finger movements during finger Braille typing. Investigation on the character-input interface indicated that characters could be input stably by contraction of (a the masseter, (b trapezius, (c anterior tibialis and (d flexor carpi ulnaris muscles. This wide applicability is desirable when the interface is applied to persons with physical disabilities because the disability differs one to another. The investigation also demonstrated that the electrode module can work properly without any skin preparation. Finger movement detection experiments showed that each finger movement was more clearly detectable when comparing to EMGs recorded with conventional electrodes, suggesting that the Laplacian electrode module is more suitable for detecting the timing of finger movement during typing. This could be because the Laplacian configuration enables us to record EMGs just beneath the electrode. These results demonstrate the advantages of the Laplacian electrode module.

  1. Comparison of muscle force, muscle endurance, and electromyogram activity during an expedition at high altitude

    Science.gov (United States)

    Terasawa, K.; Fujiwara, T.; Sakai, A.; Yanagidaira, N.; Asano, K.; Yanagisawa, K.; Kashimura, N.; Ueda, G.; Wu, T.; Zhang, Y.

    1996-09-01

    Handgrip force (HF), maximal pinch force (MF), muscle endurance (ME), and the median power frequency (MdPF) of the activity shown in the electromyogram (EMG) were studied at various altitudes in eight normal healthy subjects. MF and ME were measured between the index finger and thumb, and all measurements were obtained at altitudes ranging from 610 to 4860 m during an expedition in the Qinghai Plateau in China. With the change in altitude HF, ME, and MF showed no significant change. Compared to the MdPF at 2260 m on ascent, the MdPF at other altitudes showed a significant decrease ( Pmuscle performance (HF, MF, and ME) was not affected by the environment at high altitude. However, MdPF was affected and the mean MdPF at 610 m after the expedition did not recover to initial values of MdPF. We suggest these results may have been affected by fatigue and chronic exposure to the hypobaric hypoxic environment, since the members of the expedition party expressed feelings of sluggishness and fatigue after the expedition.

  2. Difficulty adaptation in a competitive arm rehabilitation game using real-time control of arm electromyogram and respiration.

    Science.gov (United States)

    Darzi, A; Gorsic, M; Novak, D

    2017-07-01

    Rehabilitation robots are often combined with serious games that motivate patients and keep them exercising at high intensities. A promising type of game are competitive rehabilitation games, but few difficulty adaptation algorithms have been presented for them. This paper thus presents the adaptation of difficulty in a competitive arm rehabilitation game based on two physiological signals: respiration and electromyography of the posterior deltoid. It consists of three smaller studies: an open-loop respiration study, a closed-loop respiration study (where a controller attempts to maintain respiration rate at preset levels), and a closed-loop electromyogram study (where a controller attempts to keep the electromyogram at preset levels). The studies control two difficulty parameters based on the physiological responses of one of the two exercising participants, though the ultimate goal is to control the physiological responses of both participants. Furthermore, all three studies are done with unimpaired participants. The closed-loop controllers achieved high correlation coefficients between desired and measured levels of respiration rate (r = 0.83) and electromyogram (r = 0.89), demonstrating that it is possible to control the physiological responses of unimpaired participants in a competitive arm rehabilitation game, thus controlling their level of workload and exercise intensity. In the future, the proposed method will be tested with patients undergoing rehabilitation.

  3. Correlation analysis between surface electromyography and continuous-wave near-infrared spectroscopy parameters during isometric exercise to volitional fatigue

    OpenAIRE

    ŞAYLİ, Ömer; AKIN, Ata; ÇOTUK, Hasan Birol

    2014-01-01

    In this study, the process of muscular fatigue was examined using surface electromyography (sEMG) and continuous-wave near-infrared spectroscopy (cw-NIRS) simultaneously during an isometric hand grip exercise at 50% and 75% of the maximal voluntary contraction (MVC), sustained until volitional fatigue. The mean frequency of the sEMG decreased during the whole exercise, whereas the root mean square had a tendency to increase. Oxyhemoglobin/deoxyhemoglobin concentration changes computed ...

  4. Improving the Robustness of Electromyogram-Pattern Recognition for Prosthetic Control by a Postprocessing Strategy

    Directory of Open Access Journals (Sweden)

    Xu Zhang

    2017-09-01

    Full Text Available Electromyogram (EMG contains rich information for motion decoding. As one of its major applications, EMG-pattern recognition (PR-based control of prostheses has been proposed and investigated in the field of rehabilitation robotics for decades. These prostheses can offer a higher level of dexterity compared to the commercially available ones. However, limited progress has been made toward clinical application of EMG-PR-based prostheses, due to their unsatisfactory robustness against various interferences during daily use. These interferences may lead to misclassifications of motion intentions, which damage the control performance of EMG-PR-based prostheses. A number of studies have applied methods that undergo a postprocessing stage to determine the current motion outputs, based on previous outputs or other information, which have proved effective in reducing erroneous outputs. In this study, we proposed a postprocessing strategy that locks the outputs during the constant contraction to block out occasional misclassifications, upon detecting the motion onset using a threshold. The strategy was investigated using three different motion onset detectors, namely mean absolute value, Teager–Kaiser energy operator, or mechanomyogram (MMG. Our results indicate that the proposed strategy could suppress erroneous outputs, during rest and constant contractions in particular. In addition, with MMG as the motion onset detector, the strategy was found to produce the most significant improvement in the performance, reducing the total errors up to around 50% (from 22.9 to 11.5% in comparison to the original classification output in the online test, and it is the most robust against threshold value changes. We speculate that motion onset detectors that are both smooth and responsive would further enhance the efficacy of the proposed postprocessing strategy, which would facilitate the clinical application of EMG-PR-based prosthetic control.

  5. Continuous Estimation of Human Multi-Joint Angles From sEMG Using a State-Space Model.

    Science.gov (United States)

    Ding, Qichuan; Han, Jianda; Zhao, Xingang

    2017-09-01

    Due to the couplings among joint-relative muscles, it is a challenge to accurately estimate continuous multi-joint movements from multi-channel sEMG signals. Traditional approaches always build a nonlinear regression model, such as artificial neural network, to predict the multi-joint movement variables using sEMG as inputs. However, the redundant sEMG-data are always not distinguished; the prediction errors cannot be evaluated and corrected online as well. In this work, a correlation-based redundancy-segmentation method is proposed to segment the sEMG-vector including redundancy into irredundant and redundant subvectors. Then, a general state-space framework is developed to build the motion model by regarding the irredundant subvector as input and the redundant one as measurement output. With the built state-space motion model, a closed-loop prediction-correction algorithm, i.e., the unscented Kalman filter (UKF), can be employed to estimate the multi-joint angles from sEMG, where the redundant sEMG-data are used to reject model uncertainties. After having fully employed the redundancy, the proposed method can provide accurate and smooth estimation results. Comprehensive experiments are conducted on the multi-joint movements of the upper limb. The maximum RMSE of the estimations obtained by the proposed method is 0.16±0.03, which is significantly less than 0.25±0.06 and 0.27±0.07 (p < 0.05) obtained by common neural networks.

  6. Electromyogram synergy control of a dexterous artificial hand to unscrew and screw objects.

    Science.gov (United States)

    Kent, Benjamin A; Karnati, Nareen; Engeberg, Erik D

    2014-03-21

    Due to their limited dexterity, it is currently not possible to use a commercially available prosthetic hand to unscrew or screw objects without using elbow and shoulder movements. For these tasks, prosthetic hands function like a wrench, which is unnatural and limits their use in tight working environments. Results from timed rotational tasks with human subjects demonstrate the clinical need for increased dexterity of prosthetic hands, and a clinically viable solution to this problem is presented for an anthropomorphic artificial hand. Initially, a human hand motion analysis was performed during a rotational task. From these data, human hand synergies were derived and mapped to an anthropomorphic artificial hand. The synergy for the artificial hand is controlled using conventional dual site electromyogram (EMG) signals. These EMG signals were mapped to the developed synergy to control four joints of the dexterous artificial hand simultaneously.Five limb absent and ten able-bodied test subjects participated in a comparison study to complete a timed rotational task as quickly as possible with their natural hands (except for one subject with a bilateral hand absence), eight commercially available prosthetic hands, and the proposed synergy controller. Each test subject used two to four different artificial hands. With the able-bodied subjects, the developed synergy controller reduced task completion time by 177% on average. The limb absent subjects completed the task faster on average than with their own prostheses by 46%. There was a statistically significant improvement in task completion time with the synergy controller for three of the four limb absent participants with integrated prostheses, and was not statistically different for the fourth. The proposed synergy controller reduced average task completion time compared to commercially available prostheses. Additionally, the synergy controller is able to function in a small workspace and requires less physical

  7. Electromyogram pattern recognition for control of powered upper-limb prostheses: state of the art and challenges for clinical use.

    Science.gov (United States)

    Scheme, Erik; Englehart, Kevin

    2011-01-01

    Using electromyogram (EMG) signals to control upper-limb prostheses is an important clinical option, offering a person with amputation autonomy of control by contracting residual muscles. The dexterity with which one may control a prosthesis has progressed very little, especially when controlling multiple degrees of freedom. Using pattern recognition to discriminate multiple degrees of freedom has shown great promise in the research literature, but it has yet to transition to a clinically viable option. This article describes the pertinent issues and best practices in EMG pattern recognition, identifies the major challenges in deploying robust control, and advocates research directions that may have an effect in the near future.

  8. Implementation of a real-time automatic onset time detection for surface electromyography measurement systems using NI myRIO

    Directory of Open Access Journals (Sweden)

    Lersviriyanantakul Chaiwat

    2016-01-01

    Full Text Available For using surface electromyography (sEMG in various applications, the process consists of three parts: an onset time detection for detecting the first point of movement signals, a feature extraction for extracting the signal attribution, and a feature classification for classifying the sEMG signals. The first and the most significant part that influences the accuracy of other parts is the onset time detection, particularly for automatic systems. In this paper, an automatic and simple algorithm for the real-time onset time detection is presented. There are two main processes in the proposed algorithm; a smoothing process for reducing the noise of the measured sEMG signals and an automatic threshold calculation process for determining the onset time. The results from the algorithm analysis demonstrate the performance of the proposed algorithm to detect the sEMG onset time in various smoothing-threshold equations. Our findings reveal that using a simple square integral (SSI as the smoothing-threshold equation with the given sEMG signals gives the best performance for the onset time detection. Additionally, our proposed algorithm is also implemented on a real hardware platform, namely NI myRIO. Using the real-time simulated sEMG data, the experimental results guarantee that the proposed algorithm can properly detect the onset time in the real-time manner.

  9. Reliability of surface EMG measurements from the suprahyoid muscle complex

    DEFF Research Database (Denmark)

    Kothari, Mohit; Stubbs, Peter William; Pedersen, Asger Roer

    2017-01-01

    of using the suprahyoid muscle complex (SMC) using surface electromyography (sEMG) to assess changes to neural pathways by determining the reliability of measurements in healthy participants over days. Methods: Seventeen healthy participants were recruited. Measurements were performed twice with one week...... between sessions. Single pulse (at 120% and 140% of the resting motor threshold (rMT)) and paired pulse (2 ms and 15 ms paired pulse) transcranial magnetic stimulation (TMS) were used to elicit MEPs in the SMC which were recorded using sEMG. Results: ≈50% of participants (range: 42%-58%; depending...... on stimulus type/intensity) had significantly different MEP values between day 1 and day 2 for single pulse and paired pulse TMS. A large stimulus artefact resulted in MEP responses that could not be assessed in four participants. Conclusions: The assessment of the SMC using sEMG following TMS was poorly...

  10. Dexterous hand gestures recognition based on low-density sEMG signals for upper-limb forearm amputees

    Directory of Open Access Journals (Sweden)

    John Jairo Villarejo Mayor

    2017-08-01

    Full Text Available Abstract Introduction Intuitive prosthesis control is one of the most important challenges in order to reduce the user effort in learning how to use an artificial hand. This work presents the development of a novel method for pattern recognition of sEMG signals able to discriminate, in a very accurate way, dexterous hand and fingers movements using a reduced number of electrodes, which implies more confidence and usability for amputees. Methods The system was evaluated for ten forearm amputees and the results were compared with the performance of able-bodied subjects. Multiple sEMG features based on fractal analysis (detrended fluctuation analysis and Higuchi’s fractal dimension combined with traditional magnitude-based features were analyzed. Genetic algorithms and sequential forward selection were used to select the best set of features. Support vector machine (SVM, K-nearest neighbors (KNN and linear discriminant analysis (LDA were analyzed to classify individual finger flexion, hand gestures and different grasps using four electrodes, performing contractions in a natural way to accomplish these tasks. Statistical significance was computed for all the methods using different set of features, for both groups of subjects (able-bodied and amputees. Results The results showed average accuracy up to 99.2% for able-bodied subjects and 98.94% for amputees using SVM, followed very closely by KNN. However, KNN also produces a good performance, as it has a lower computational complexity, which implies an advantage for real-time applications. Conclusion The results show that the method proposed is promising for accurately controlling dexterous prosthetic hands, providing more functionality and better acceptance for amputees.

  11. Surface electromyography as a screening method for evaluation of dysphagia and odynophagia

    Directory of Open Access Journals (Sweden)

    Eviatar Ephraim

    2009-02-01

    Full Text Available Abstract Objective Patients suspected of having swallowing disorders, could highly benefit from simple diagnostic screening before being referred to specialist evaluations. The article analyzes various instrumental methods of dysphagia assessment, introduces surface electromyography (sEMG to carry out rapid assessment of such patients, and debates proposed suggestions for sEMG screening protocol in order to identify abnormal deglutition. Data sources Subject related books and articles from 1813 to 2007 were obtained through library search, MEDLINE (1949–2007 and EMBASE (1975–2007. Methods Specifics steps for establishing the protocol for applying the technique for screening purposes (e.g., evaluation of specific muscles, the requirements for diagnostic sEMG equipment, the sEMG technique itself, and defining the tests suitable for assessing deglutition (e.g., saliva, normal, and excessive swallows and uninterrupted drinking of water are presented in detail. SEMG is compared with other techniques in terms of cost, timing, involvement of radiation, etc. Results According to the published data, SEMG of swallowing is a simple and reliable method for screening and preliminary differentiation among dysphagia and odynophagia of various origins. This noninvasive radiation-free examination has a low level of discomfort, and is simple, time-saving and inexpensive to perform. The major weakness of the method seems to be inability for precise diagnostic of neurologically induced dysphagia. Conclusion With standardization of the technique and an established normative database, sEMG might serve as a reliable screening method for optimal patient management but cannot serve for proper investigation of neurogenic dysphagia.

  12. Surface electromyography as a screening method for evaluation of dysphagia and odynophagia

    Science.gov (United States)

    Vaiman, Michael; Eviatar, Ephraim

    2009-01-01

    Objective Patients suspected of having swallowing disorders, could highly benefit from simple diagnostic screening before being referred to specialist evaluations. The article analyzes various instrumental methods of dysphagia assessment, introduces surface electromyography (sEMG) to carry out rapid assessment of such patients, and debates proposed suggestions for sEMG screening protocol in order to identify abnormal deglutition. Data sources Subject related books and articles from 1813 to 2007 were obtained through library search, MEDLINE (1949–2007) and EMBASE (1975–2007). Methods Specifics steps for establishing the protocol for applying the technique for screening purposes (e.g., evaluation of specific muscles), the requirements for diagnostic sEMG equipment, the sEMG technique itself, and defining the tests suitable for assessing deglutition (e.g., saliva, normal, and excessive swallows and uninterrupted drinking of water) are presented in detail. SEMG is compared with other techniques in terms of cost, timing, involvement of radiation, etc. Results According to the published data, SEMG of swallowing is a simple and reliable method for screening and preliminary differentiation among dysphagia and odynophagia of various origins. This noninvasive radiation-free examination has a low level of discomfort, and is simple, time-saving and inexpensive to perform. The major weakness of the method seems to be inability for precise diagnostic of neurologically induced dysphagia. Conclusion With standardization of the technique and an established normative database, sEMG might serve as a reliable screening method for optimal patient management but cannot serve for proper investigation of neurogenic dysphagia. PMID:19232090

  13. Motor unit action potential conduction velocity estimated from surface electromyographic signals using image processing techniques.

    Science.gov (United States)

    Soares, Fabiano Araujo; Carvalho, João Luiz Azevedo; Miosso, Cristiano Jacques; de Andrade, Marcelino Monteiro; da Rocha, Adson Ferreira

    2015-09-17

    In surface electromyography (surface EMG, or S-EMG), conduction velocity (CV) refers to the velocity at which the motor unit action potentials (MUAPs) propagate along the muscle fibers, during contractions. The CV is related to the type and diameter of the muscle fibers, ion concentration, pH, and firing rate of the motor units (MUs). The CV can be used in the evaluation of contractile properties of MUs, and of muscle fatigue. The most popular methods for CV estimation are those based on maximum likelihood estimation (MLE). This work proposes an algorithm for estimating CV from S-EMG signals, using digital image processing techniques. The proposed approach is demonstrated and evaluated, using both simulated and experimentally-acquired multichannel S-EMG signals. We show that the proposed algorithm is as precise and accurate as the MLE method in typical conditions of noise and CV. The proposed method is not susceptible to errors associated with MUAP propagation direction or inadequate initialization parameters, which are common with the MLE algorithm. Image processing -based approaches may be useful in S-EMG analysis to extract different physiological parameters from multichannel S-EMG signals. Other new methods based on image processing could also be developed to help solving other tasks in EMG analysis, such as estimation of the CV for individual MUs, localization and tracking of innervation zones, and study of MU recruitment strategies.

  14. Surface EMG signals based motion intent recognition using multi-layer ELM

    Science.gov (United States)

    Wang, Jianhui; Qi, Lin; Wang, Xiao

    2017-11-01

    The upper-limb rehabilitation robot is regard as a useful tool to help patients with hemiplegic to do repetitive exercise. The surface electromyography (sEMG) contains motion information as the electric signals are generated and related to nerve-muscle motion. These sEMG signals, representing human's intentions of active motions, are introduced into the rehabilitation robot system to recognize upper-limb movements. Traditionally, the feature extraction is an indispensable part of drawing significant information from original signals, which is a tedious task requiring rich and related experience. This paper employs a deep learning scheme to extract the internal features of the sEMG signals using an advanced Extreme Learning Machine based auto-encoder (ELMAE). The mathematical information contained in the multi-layer structure of the ELM-AE is used as the high-level representation of the internal features of the sEMG signals, and thus a simple ELM can post-process the extracted features, formulating the entire multi-layer ELM (ML-ELM) algorithm. The method is employed for the sEMG based neural intentions recognition afterwards. The case studies show the adopted deep learning algorithm (ELM-AE) is capable of yielding higher classification accuracy compared to the Principle Component Analysis (PCA) scheme in 5 different types of upper-limb motions. This indicates the effectiveness and the learning capability of the ML-ELM in such motion intent recognition applications.

  15. Long-term surface EMG monitoring using K-means clustering and compressive sensing

    Science.gov (United States)

    Balouchestani, Mohammadreza; Krishnan, Sridhar

    2015-05-01

    In this work, we present an advanced K-means clustering algorithm based on Compressed Sensing theory (CS) in combination with the K-Singular Value Decomposition (K-SVD) method for Clustering of long-term recording of surface Electromyography (sEMG) signals. The long-term monitoring of sEMG signals aims at recording of the electrical activity produced by muscles which are very useful procedure for treatment and diagnostic purposes as well as for detection of various pathologies. The proposed algorithm is examined for three scenarios of sEMG signals including healthy person (sEMG-Healthy), a patient with myopathy (sEMG-Myopathy), and a patient with neuropathy (sEMG-Neuropathr), respectively. The proposed algorithm can easily scan large sEMG datasets of long-term sEMG recording. We test the proposed algorithm with Principal Component Analysis (PCA) and Linear Correlation Coefficient (LCC) dimensionality reduction methods. Then, the output of the proposed algorithm is fed to K-Nearest Neighbours (K-NN) and Probabilistic Neural Network (PNN) classifiers in order to calclute the clustering performance. The proposed algorithm achieves a classification accuracy of 99.22%. This ability allows reducing 17% of Average Classification Error (ACE), 9% of Training Error (TE), and 18% of Root Mean Square Error (RMSE). The proposed algorithm also reduces 14% clustering energy consumption compared to the existing K-Means clustering algorithm.

  16. Selective Linear-Regression Model for hand posture discrimination and grip force estimation using surface electromyogram signals.

    Science.gov (United States)

    Yamanoi, Yusuke; Morishita, Soichiro; Kato, Ryu; Yokoi, Hiroshi

    2015-01-01

    This paper proposes the method of hand posture discrimination and grip force estimation by means of Selective Linear-Regression Model. Generally, myoelectric hands which discriminate hand posture and estimate grip force at the same time result in unsatisfying results because of complication of EMG signals. Therefore, most of myoelectric hands can control either the force or the posture. However, the proposed method is able to discriminate hand posture and to estimate grip force simultaneously while the accuracy results are achieved. In experiments, EMG signals were measured while hand posture and grip force were changing. As a result, it appears that EMG features increase monotonically with grip force. In addition, increasing forms of EMG features are different on each posture. Based on these experimental results, the authors propose the method for both discriminating hand posture and estimating grip force by means of several linear-regression models which utilize the relationship between the grip force and EMG features on each posture. To evaluate the effectiveness of this method, the failure rates of discrimination and the estimation errors of the proposed method were employed. The results indicate that failure rates and estimation errors are improved significantly.

  17. The practical use of surface electromyography during running: does the evidence support the hype? A narrative review.

    Science.gov (United States)

    Subbu, R; Weiler, R; Whyte, G

    2015-01-01

    Surface electromyography (sEMG) is a commonly used technique to investigate muscle activation and fatigue, which is non-invasive and can allow for continuous measurement. Systematic research on the use of sEMG in the sporting environment has been on-going for many years and predominantly based on cycling and rowing activities. To date there have been no reviews assessing the validity and reliability in sEMG exclusively in running activities specifically during on-field testing. The purpose of this review is to evaluate the use of sEMG in the practical context and whether this be translated to on-field testing. Electronic literature searches were performed using the Cochrane Library, PUBMED, CINAHL and PeDro without restrictions on the study date to identify the relevant current English language literature. 10 studies were relevant after title and content review. All the studies identified were all level three evidence based. The general trends of the sEMG activity appear to correlate with running velocity and muscle fatigue seems almost always the consequence of prolonged, dynamic activity. However, these changes are not consistently measured or statistically significant throughout the studies raising the question of the accuracy and reliability when analysing sEMG measurements and making assumptions about the cause of fatigue. An agreed consensus when measuring and analysing sEMG data during running activities particularly in field testing with the most appropriate study design and reliable methodology is yet to be determined and further studies are required.

  18. Fatigue-associated changes in the electromyogram of the human first dorsal interosseous muscle

    NARCIS (Netherlands)

    Zijdewind, Inge; Zwarts, MJ; Kernell, D

    1999-01-01

    Muscle fatigue is a clinically important symptom, often analyzed using electromyography (EMG). We analyzed fatigue reactions of the first dorsal interosseous muscle (FDI) during a maintained contraction at half-maximal force (1/2-MVC test). EMGs were recorded with large surface electrodes and,

  19. Muscle conduction velocity, surface electromyography variables, and echo intensity during concentric and eccentric fatigue.

    Science.gov (United States)

    Gonzalez-Izal, Miriam; Lusa Cadore, Eduardo; Izquierdo, Mikel

    2014-03-01

    Concentric (CON) and eccentric (ECC) contractions may involve different mechanisms related to changes in sarcolemma status and the consequent alteration of action potential transmission along muscle fibers. Muscle conduction velocity (CV), surface electromyography signal (sEMG), muscle quality, and blood lactate concentrations were analyzed during CON and ECC actions. Compared with ECC, the CON protocol resulted in greater muscle force losses, blood lactate concentrations, and changes in sEMG parameters. Similar reductions in CV were detected in both protocols. Higher echo intensity values were observed 2 days after ECC due to greater muscle damage. The effects of the muscle damage produced by ECC exercise on the transmission of action potentials along muscle fibers (measured as the CV) may be comparable with the effects of hydrogen accumulation produced by CON exercise (related to greater lactate concentrations), which causes greater force loss and change in other sEMG variables during CON than during ECC actions.

  20. Electromyogram-controlled assistive exercise for the motor recovery of shoulder in chronic hemiplegia: A pilot study.

    Science.gov (United States)

    Park, Byung Kyu; Kim, Ji-Won; Kwon, Yuri; Heo, Jae-Hoon; Yoon, Joo-Seok; Eom, Gwang-Moon

    2015-01-01

    Correct-active-repetitive exercise is important for the motor recovery in hemiplegics. The present study hypothesizes that the electromyogram (EMG)-controlled assistance of motion would be an effective implementation of the concept for the rehabilitation of the hemiplegic shoulder, even in chronic patients. This study aims to investigate the feasibility of the suggested method. The motor intention is derived from the EMG of the shoulder muscles and the shoulder movement (flexion and abduction) is assisted by an electro-mechanical system only when the motor intention (EMG amplitude) exceeded the threshold. Twelve patients in the chronic stage of stroke participated in this pilot study. The EMG-controlled assistive exercise lasts for two weeks, 20 min per day and 5 days a week. The active range of motion in both abduction and flexion increases significantly after the intervention (p shoulder-related items (p shoulder-unrelated items of the upper extremity (p = 0.13) nor in the lower extremity items (p = 0.19). This pilot study demonstrates that EMG-controlled assistive exercise can improve shoulder motor functions related to selected muscles and the suggested method is promising for the motor recovery of the shoulder in chronic hemiplegia.

  1. Evidence of long term muscle fatigue following prolonged intermittent contractions based on mechano- and electromyograms

    DEFF Research Database (Denmark)

    Søgaard, K; Blangsted, A K; Jørgensen, L V

    2003-01-01

    The focus of the present study is the long term element of muscle fatigue provoked by prolonged intermittent contractions at submaximal force levels and analysed by force, surface electromyography (EMG) and mechanomyogram (MMG). It was hypothesized that fatigue related changes in mechanical...... performance of the biceps muscle are more strongly reflected in low than in high force test contractions, more prominent in the MMG than in the EMG signal and less pronounced following contractions controlled by visual compared to proprioceptive feedback. Further, it was investigated if fatigue induced by 30...... min intermittent contractions at 30% as well as 10% of maximal voluntary contraction (MVC) lasted more than 30 min recovery. In six male subjects the EMG and MMG were recorded from the biceps brachii muscle during three sessions with fatiguing exercise at 10% with visual feedback and at 30% MVC...

  2. Comparative study of wavelet denoising in myoelectric control applications.

    Science.gov (United States)

    Sharma, Tanu; Veer, Karan

    2016-01-01

    Here, the wavelet analysis has been investigated to improve the quality of myoelectric signal before use in prosthetic design. Effective Surface Electromyogram (SEMG) signals were estimated by first decomposing the obtained signal using wavelet transform and then analysing the decomposed coefficients by threshold methods. With the appropriate choice of wavelet, it is possible to reduce interference noise effectively in the SEMG signal. However, the most effective wavelet for SEMG denoising is chosen by calculating the root mean square value and signal power values. The combined results of root mean square value and signal power shows that wavelet db4 performs the best denoising among the wavelets. Furthermore, time domain and frequency domain methods were applied for SEMG signal analysis to investigate the effect of muscle-force contraction on the signal. It was found that, during sustained contractions, the mean frequency (MNF) and median frequency (MDF) increase as muscle force levels increase.

  3. High Quality Acquisition of Surface Electromyography - Conditioning Circuit Design

    Science.gov (United States)

    Shobaki, Mohammed M.; Malik, Noreha Abdul; Khan, Sheroz; Nurashikin, Anis; Haider, Samnan; Larbani, Sofiane; Arshad, Atika; Tasnim, Rumana

    2013-12-01

    The acquisition of Surface Electromyography (SEMG) signals is used for many applications including the diagnosis of neuromuscular diseases, and prosthesis control. The diagnostic quality of the SEMG signal is highly dependent on the conditioning circuit of the SEMG acquisition system. This paper presents the design of an SEMG conditioning circuit that can guarantee to collect high quality signal with high SNR such that it is immune to environmental noise. The conditioning circuit consists of four stages; consisting of an instrumentation amplifier that is used with a gain of around 250; 4th order band pass filter in the 20-500Hz frequency range as the two initial stages. The third stage is an amplifier with adjustable gain using a variable resistance; the gain could be changed from 1000 to 50000. In the final stage the signal is translated to meet the input requirements of data acquisition device or the ADC. Acquisition of accurate signals allows it to be analyzed for extracting the required characteristic features for medical and clinical applications. According to the experimental results, the value of SNR for collected signal is 52.4 dB which is higher than the commercial system, the power spectrum density (PSD) graph is also presented and it shows that the filter has eliminated the noise below 20 Hz.

  4. The Ninapro database: A resource for sEMG naturally controlled robotic hand prosthetics.

    Science.gov (United States)

    Atzori, Manfredo; Muller, Henning

    2015-01-01

    The dexterous natural control of robotic prosthetic hands with non-invasive techniques is still a challenge: surface electromyography gives some control capabilities but these are limited, often not natural and require long training times; the application of pattern recognition techniques recently started to be applied in practice. While results in the scientific literature are promising they have to be improved to reach the real needs. The Ninapro database aims to improve the field of naturally controlled robotic hand prosthetics by permitting to worldwide research groups to develop and test movement recognition and force control algorithms on a benchmark database. Currently, the Ninapro database includes data from 67 intact subjects and 11 amputated subject performing approximately 50 different movements. The data are aimed at permitting the study of the relationships between surface electromyography, kinematics and dynamics. The Ninapro acquisition protocol was created in order to be easy to be reproduced. Currently, the number of datasets included in the database is increasing thanks to the collaboration of several research groups.

  5. Effect of Vibration Training on Anaerobic Power and Quardroceps Surface EMG in Long Jumpers

    Science.gov (United States)

    Liu, Bin; Luo, Jiong

    2015-01-01

    Objective: To explore the anaerobic power and surface EMG (sEMG) of quardrocep muscle in lower extremities after single vibration training intervention. Methods: 8 excellent male long jumpers voluntarily participated in this study. Four intervention modes were devised, including high frequency high amplitude (HFHA,30Hz,6mm), low frequency low…

  6. Validity and Reliability of Surface Electromyography Measurements from a Wearable Athlete Performance System

    Directory of Open Access Journals (Sweden)

    Scott K. Lynn, Casey M. Watkins, Megan A. Wong, Katherine Balfany, Daniel F. Feeney

    2018-06-01

    Full Text Available The Athos ® wearable system integrates surface electromyography (sEMG electrodes into the construction of compression athletic apparel. The Athos system reduces the complexity and increases the portability of collecting EMG data and provides processed data to the end user. The objective of the study was to determine the reliability and validity of Athos as compared with a research grade sEMG system. Twelve healthy subjects performed 7 trials on separate days (1 baseline trial and 6 repeated trials. In each trial subjects wore the wearable sEMG system and had a research grade sEMG system’s electrodes placed just distal on the same muscle, as close as possible to the wearable system’s electrodes. The muscles tested were the vastus lateralis (VL, vastus medialis (VM, and biceps femoris (BF. All testing was done on an isokinetic dynamometer. Baseline testing involved performing isometric 1 repetition maximum tests for the knee extensors and flexors and three repetitions of concentric-concentric knee flexion and extension at MVC for each testing speed: 60, 180, and 300 deg/sec. Repeated trials 2-7 each comprised 9 sets where each set included three repetitions of concentric-concentric knee flexion-extension. Each repeated trial (2-7 comprised one set at each speed and percent MVC (50%, 75%, 100% combination. The wearable system and research grade sEMG data were processed using the same methods and aligned in time. The amplitude metrics calculated from the sEMG for each repetition were the peak amplitude, sum of the linear envelope, and 95th percentile. Validity results comprise two main findings. First, there is not a significant effect of system (Athos or research grade system on the repetition amplitude metrics (95%, peak, or sum. Second, the relationship between torque and sEMG is not significantly different between Athos and the research grade system. For reliability testing, the variation across trials and averaged across speeds was 0.8%, 7

  7. The management of lactose intolerance among primary care physicians and its correlation with management by gastroenterologists: the SEPD-SEMG national survey

    Directory of Open Access Journals (Sweden)

    Federico Argüelles-Arias

    2015-09-01

    Full Text Available Introduction and aims: The understanding of lactose intolerance (LI is limited in some professional settings. Sociedad Española de Patología Digestiva (SEPD and Sociedad Española de Medicina General (SEMG have developed a survey in order to: a Analyze primary care physicians (PCPs knowledge and clinical management; and b to compare results with those of a previous survey of Spanish gastroenterologists (GEs. Material and methods: An online questionnaire was sent to SEMG members with 27 items on various issues: Demographics, occupational characteristics, outlook on LI, diagnostic tests, treatment, and follow-up. Results were compared to those from a survey of GEs. Results: A total of 456 PCPs responded, versus 477 GEs. PCPs had an older mean age and longer professional experience. Level of understanding of LI was similar, albeit a higher proportion of PCPs lacked epidemiological awareness (p 0.001, and LI symptoms as overlapping those of irritable bowel syndrome (93.5 vs. 88.2%; p = 0.005, although symptoms perceived as suspicious of LI were similar in both groups. Dietary recommendations were recognized as the primary therapeutic approach. Conclusion: This study reveals the outlook of PCPs on LI, and allows comparison with that of GEs, as a basis for the development of strategies aimed at improving LI understanding, approach and management in our setting.

  8. The management of lactose intolerance among primary care physicians and its correlation with management by gastroenterologists: the SEPD-SEMG national survey.

    Science.gov (United States)

    Argüelles-Arias, Federico; Rodríguez Ledo, Pilar; Tenías, José María; Otero, Mercedes; Casellas, Francesc; Blay Cortés, Guadalupe; Lucendo, Alfredo; Domínguez-Jiménez, José Luis; Carballo, Fernando

    2015-09-01

    The understanding of lactose intolerance (LI) is limited in some professional settings. Sociedad Española de Patología Digestiva (SEPD) and Sociedad Española de Medicina General (SEMG) have developed a survey in order to: a) Analyze primary care physicians (PCPs) knowledge and clinical management; and b) to compare results with those of a previous survey of Spanish gastroenterologists (GEs). An online questionnaire was sent to SEMG members with 27 items on various issues: Demographics, occupational characteristics, outlook on LI, diagnostic tests, treatment, and follow-up. Results were compared to those from a survey of GEs. A total of 456 PCPs responded, versus 477 GEs. PCPs had an older mean age and longer professional experience. Level of understanding of LI was similar, albeit a higher proportion of PCPs lacked epidemiological awareness (p 0.001), and LI symptoms as overlapping those of irritable bowel syndrome (93.5 vs. 88.2%; p = 0.005), although symptoms perceived as suspicious of LI were similar in both groups. Dietary recommendations were recognized as the primary therapeutic approach. This study reveals the outlook of PCPs on LI, and allows comparison with that of GEs, as a basis for the development of strategies aimed at improving LI understanding, approach and management in our setting.

  9. Evaluation of muscle fatigue of wheelchair basketball players with spinal cord injury using recurrence quantification analysis of surface EMG.

    Science.gov (United States)

    Uzun, S; Pourmoghaddam, A; Hieronymus, M; Thrasher, T A

    2012-11-01

    Wheelchair basketball is the most popular exercise activity among individuals with spinal cord injury (SCI). The purpose of this study was to investigate muscular endurance and fatigue in wheelchair basketball athletes with SCI using surface electromyography (SEMG) and maximal torque values. SEMG characteristics of 10 wheelchair basketball players (WBP) were compared to 13 able-bodied basketball players and 12 sedentary able-bodied subjects. Participants performed sustained isometric elbow flexion at 50% maximal voluntary contraction until exhaustion. Elbow flexion torque and SEMG signals were recorded from three elbow flexor muscles: biceps brachii longus, biceps brachii brevis and brachioradialis. SEMG signals were clustered into 0.5-s epochs with 50% overlap. Root mean square (RMS) and median frequency (MDF) of SEMG signals were calculated for each muscle and epoch as traditional fatigue monitoring. Recurrence quantification analysis was used to extract the percentage of determinism (%DET) of SEMG signals. The slope of the %DET for basketball players and WBP showed slower increase with time than the sedentary able-bodied control group for three different elbow flexor muscles, while no difference was observed for the slope of the %DET between basketball and WBP. This result indicated that the athletes are less fatigable during the task effort than the nonathletes. Normalized MDF slope decay exhibited similar results between the groups as %DET, while the slope of the normalized RMS failed to show any significant differences among the groups (p > 0.05). MDF and %DET could be useful for the evaluation of muscle fatigue in wheelchair basketball training. No conclusions about special training for WBP could be determined.

  10. Surface electromyography can quantify temporal and spatial patterns of activation of intrinsic human foot muscles.

    Science.gov (United States)

    Ferrari, E; Cooper, G; Reeves, N D; Hodson-Tole, E F

    2018-04-01

    Intrinsic foot muscles (IFM) are a crucial component within the human foot. Investigating their functioning can help understand healthy and pathological behaviour of foot and ankle, fundamental for everyday activities. Recording muscle activation from IFM has been attempted with invasive techniques, mainly investigating single muscles. Here we present a novel methodology, to investigate the feasibility of recording physiological surface EMG (sEMG) non-invasively and quantify patterns of activation across the whole plantar region of the foot. sEMG were recorded with a 13 × 5 array from the sole of the foot (n = 25) during two-foot stance, two-foot tiptoe and anterior/posterior sways. Physiological features of sEMG were analysed. During anterior/posterior epochs within the sway task, sEMG patterns were analysed in terms of signal amplitude (intensity) and structure (Sample Entropy) distribution, by evaluating the centre of gravity (CoG) of each topographical map. Results suggest signals are physiological and not affected by loading. Both amplitude and sample entropy CoG coordinates were grouped in one region and overlapped, suggesting that the region with highest amplitude corresponds with the most predictable signal. Therefore, both spatial and temporal features of IFM activation may be recorded non-invasively, providing opportunity for more detailed investigation of IFM function in healthy and patient populations. Copyright © 2018. Published by Elsevier Ltd.

  11. Exercise muscle fatigue detection system implementation via wireless surface electromyography and empirical mode decomposition.

    Science.gov (United States)

    Chang, Kang-Ming; Liu, Shing-Hong; Wang, Jia-Jung; Cheng, Da-Chuan

    2013-01-01

    Surface electromyography (sEMG) is an important measurement for monitoring exercise and fitness. A wireless Bluetooth transmission sEMG measurement system with a sampling frequency of 2 KHz is developed. Traditional muscle fatigue is detected from the median frequency of the sEMG power spectrum. The regression slope of the linear regression of median frequency is an important muscle fatigue index. As fatigue increases, the power spectrum of the sEMG shifts toward lower frequencies. The goal of this study is to evaluate the sensitivity of empirical mode decomposition (EMD) quantifying the electrical manifestations of the local muscle fatigue during exercising in health people. We also compared this method with the raw data and discrete wavelet transform (DWT). Five male and five female volunteers participated. Each subject was asked to run on a multifunctional pedaled elliptical trainer for about 30 minutes, twice a week, and there were a total of six recording times for each subject with a wireless EMG recording system. The results show that sensitivity of the highest frequency component of EMD is better than the highest frequency component of DWT, and raw data.

  12. Improved prosthetic hand control with concurrent use of myoelectric and inertial measurements

    OpenAIRE

    Krasoulis, Agamemnon; Kyranou, Iris; Erden, Mustapha Suphi; Nazarpour, Kianoush; Vijayakumar, Sethu

    2017-01-01

    Background Myoelectric pattern recognition systems can decode movement intention to drive upper-limb prostheses. Despite recent advances in academic research, the commercial adoption of such systems remains low. This limitation is mainly due to the lack of classification robustness and a simultaneous requirement for a large number of electromyogram (EMG) electrodes. We propose to address these two issues by using a multi-modal approach which combines surface electromyography (sEMG) with inert...

  13. Analysis of one repetition during biceps curl exercise among age-matched adult volunteers using endurance, curl speed and surface electromyography signals.

    Science.gov (United States)

    Marri, Kiran; Maitra Ghosh, Diptasree; Swaminathan, Ramakrishnan

    2017-07-01

    Exercises under isometric and dynamic contractions are influenced by the rate coding and recruitment strategies. The study of muscle strength under dynamic contraction is normally performed using one-repetition maximum (1-RM) method. There are several variants of deriving one repetition method using number of repetitions and load that are useful in physical fitness and clinical rehabilitation program. However, the factors of dynamic contractions such as endurance time, speed of muscle contractions and muscle activity are not considered in 1-RM methods. The muscular activities are analyzed using surface electromyography (sEMG) signals. Limited work has been reported on the relationship between the 1-RM method and factors such as endurance time, speed of contraction and sEMG activity. In this work, a modified 1-RM method is proposed, namely, N-RM, using load, number of repetitions, endurance time, speed of contraction and normalized sEMG activity. For this purpose, sEMG signals are recorded from 58 healthy subjects under standard dynamic contraction protocol involving curl exercise. Conventional 1-RM is computed by using Epley's method and compared with proposed method using correlation analysis. The results show that 1-RM increases linearly with number of curls (r=1) but has a poor correlation coefficient with sEMG (r=0.01) and endurance time (r =0.4). The curl speed for lower 1-RM and higher 1-RM did not show any statistical difference (p =0.2). The proposed N-RM is observed to have good correlation with endurance time (r=0.734), curl speed (r=0.893) and sEMG activity (r=0.8851). These results demonstrate that the proposed N-RM is highly correlated to factors influencing the dynamic contractions. This method can be further extended to assess muscles under various clinical disorders and sports training.

  14. Estimation of Upper Limb Joint Angle Using Surface EMG Signal

    Directory of Open Access Journals (Sweden)

    Yee Mon Aung

    2013-10-01

    Full Text Available In the development of robot-assisted rehabilitation systems for upper limb rehabilitation therapy, human electromyogram (EMG is widely used due to its ability to detect the user intended motion. EMG is one kind of biological signal that can be recorded to evaluate the performance of skeletal muscles by means of a sensor electrode. Based on recorded EMG signals, user intended motion could be extracted via estimation of joint torque, force or angle. Therefore, this estimation becomes one of the most important factors to achieve accurate user intended motion. In this paper, an upper limb joint angle estimation methodology is proposed. A back propagation neural network (BPNN is developed to estimate the shoulder and elbow joint angles from the recorded EMG signals. A Virtual Human Model (VHM is also developed and integrated with BPNN to perform the simulation of the estimated angle. The relationships between sEMG signals and upper limb movements are observed in this paper. The effectiveness of our developments is evaluated with four healthy subjects and a VHM simulation. The results show that the methodology can be used in the estimation of joint angles based on EMG.

  15. Validity and Reliability of Surface Electromyography in the Assessment of Primary Muscle Tension Dysphonia.

    Science.gov (United States)

    Khoddami, Seyyedeh Maryam; Talebian, Saeed; Izadi, Farzad; Ansari, Noureddin Nakhostin

    2017-05-01

    The study aims to evaluate the reliability and the discriminative validity of surface electromyography (sEMG) in the assessment of patients with primary muscle tension dysphonia (MTD). The study design is cross-sectional. Fifteen patients with primary MTD (mean age: 34.07 ± 10.99 years) and 15 healthy volunteers (mean age: 34.53 ± 10.63 years) were included. All participants underwent evaluation of sEMG to record the electrical activity of the thyrohyoid and cricothyroid muscles. The outcome measures were the root mean square (RMS), activity peak, duration, and time to the peak activity, which were obtained during /a/ and /i/ prolongation for test-retest reliability. The test-retest reliability was good to excellent for the RMS and peak activity measures (intraclass correlation coefficient [agreement] [ICC agreement ] = 0.49-0.98). The reliability for the activity duration was poor to excellent (ICC agreement  = 0.19-0.9). Poor test-retest reliability was found for the time to peak measure (ICC agreement  = 0.15-0.37). The standard error of measurement for all sEMG measures was between 0.41 and 2.05. The smallest detectable change (SDC) was calculated between 1.13 and 5.66. The highest SDC values were obtained for the peak and the lowest SDCs were documented for the duration (5.66 and 1.13, respectively). All sEMG measures were not able to discriminate between the MTD patients and healthy subjects (P > 0.05). The sEMG is a reliable tool to measure the RMS, the peak activity, and the activity duration in primary MTD. However, it is not able to discriminate the patients with primary MTD from healthy subjects. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  16. Swallowing in patients with Parkinson's disease: a surface electromyography study.

    Science.gov (United States)

    Ws Coriolano, Maria das Graças; R Belo, Luciana; Carneiro, Danielle; G Asano, Amdore; Al Oliveira, Paulo José; da Silva, Douglas Monteiro; G Lins, Otávio

    2012-12-01

    Our goal was to study deglutition of Parkinson's disease (PD) patients and normal controls (NC) using surface electromyography (sEMG). The study included 15 patients with idiopathic PD and 15 age-matched normal controls. Surface electromyography was collected over the suprahyoid muscle group. Conditions were the following: swallow at once 10 and 20 ml of water and 5 and 10 ml of yogurt of firm consistency, and freely drink 100 ml of water. During swallowing, durations of sEMG were significantly longer in PD patients than in normal controls but no significant differences of amplitudes were found. Eighty percent of the PD patients and 20 % of the NC needed more than one swallow to consume 20 ml of water, while 70 % of the PD patients and none of the NC needed more than one swallow to consume 5 ml of yogurt. PD patients took significantly more time and needed significantly more swallows to drink 100 ml of water than normal controls. We conclude that sEMG might be a simple and useful tool to study and monitor deglutition in PD patients.

  17. A Wearable System for Recognizing American Sign Language in Real-Time Using IMU and Surface EMG Sensors.

    Science.gov (United States)

    Wu, Jian; Sun, Lu; Jafari, Roozbeh

    2016-09-01

    A sign language recognition system translates signs performed by deaf individuals into text/speech in real time. Inertial measurement unit and surface electromyography (sEMG) are both useful modalities to detect hand/arm gestures. They are able to capture signs and the fusion of these two complementary sensor modalities will enhance system performance. In this paper, a wearable system for recognizing American Sign Language (ASL) in real time is proposed, fusing information from an inertial sensor and sEMG sensors. An information gain-based feature selection scheme is used to select the best subset of features from a broad range of well-established features. Four popular classification algorithms are evaluated for 80 commonly used ASL signs on four subjects. The experimental results show 96.16% and 85.24% average accuracies for intra-subject and intra-subject cross session evaluation, respectively, with the selected feature subset and a support vector machine classifier. The significance of adding sEMG for ASL recognition is explored and the best channel of sEMG is highlighted.

  18. Evaluation of upper limb muscle fatigue based on surface electromyography.

    Science.gov (United States)

    Zhou, Qianxiang; Chen, Yuhong; Ma, Chao; Zheng, Xiaohui

    2011-10-01

    Fatigue is believed to be a major contributory factor to occupational injuries in machine operators. The development of accurate and usable techniques to measure operator fatigue is therefore important. In this study, we used a novel method based on surface electromyography (sEMG) of the biceps brachii and the Borg scale to evaluate local muscle fatigue in the upper limb after isometric muscle action. Thirteen young males performed isometric actions with the upper limb at different force levels. sEMG activities of the biceps brachii were recorded during the actions. Borg scales were used to evaluate the subjective sensation of local fatigue of the biceps brachii after the actions. sEMG activities were analyzed using the one-third band octave method, and an equation to determine the degree of fatigue was derived based on the relationship between the variable and the Borg scale. The results showed that the relationship could be expressed by a conic curve, and could be used to evaluate muscle fatigue during machine operation.

  19. Detection of surface electromyography recording time interval without muscle fatigue effect for biceps brachii muscle during maximum voluntary contraction.

    Science.gov (United States)

    Soylu, Abdullah Ruhi; Arpinar-Avsar, Pinar

    2010-08-01

    The effects of fatigue on maximum voluntary contraction (MVC) parameters were examined by using force and surface electromyography (sEMG) signals of the biceps brachii muscles (BBM) of 12 subjects. The purpose of the study was to find the sEMG time interval of the MVC recordings which is not affected by the muscle fatigue. At least 10s of force and sEMG signals of BBM were recorded simultaneously during MVC. The subjects reached the maximum force level within 2s by slightly increasing the force, and then contracted the BBM maximally. The time index of each sEMG and force signal were labeled with respect to the time index of the maximum force (i.e. after the time normalization, each sEMG or force signal's 0s time index corresponds to maximum force point). Then, the first 8s of sEMG and force signals were divided into 0.5s intervals. Mean force, median frequency (MF) and integrated EMG (iEMG) values were calculated for each interval. Amplitude normalization was performed by dividing the force signals to their mean values of 0s time intervals (i.e. -0.25 to 0.25s). A similar amplitude normalization procedure was repeated for the iEMG and MF signals. Statistical analysis (Friedman test with Dunn's post hoc test) was performed on the time and amplitude normalized signals (MF, iEMG). Although the ANOVA results did not give statistically significant information about the onset of the muscle fatigue, linear regression (mean force vs. time) showed a decreasing slope (Pearson-r=0.9462, pfatigue starts after the 0s time interval as the muscles cannot attain their peak force levels. This implies that the most reliable interval for MVC calculation which is not affected by the muscle fatigue is from the onset of the EMG activity to the peak force time. Mean, SD, and range of this interval (excluding 2s gradual increase time) for 12 subjects were 2353, 1258ms and 536-4186ms, respectively. Exceeding this interval introduces estimation errors in the maximum amplitude calculations

  20. Assessment of work-related muscle strain by using surface EMG during test contractions interposed between work periods of simulateted mushroom picking

    DEFF Research Database (Denmark)

    Ohashi, Jun-Ya; Blangsted, Anne Katrine; Nielsen, Pernille Kofoed

    2010-01-01

    Surface electromyograms(EMG) during test contractions (TCs) were studied to assess the muscle strain in simulated mushroom picking. Additionally, the duration of the TC for the effective assessment was investigated. Nine female subjects performed standardized shoulder abduction and a stooped...

  1. The integration of surface electromyography in the clinical decision making process: a case report

    Science.gov (United States)

    Nicholson, W Reg

    1998-01-01

    Objective: To demonstrate how the findings of surface electromyography (S.E.M.G.) were integrated into the clinical decision-making process. Clinical Features: This is a retrospective review of the file of a 27-year-old male suffering from mechanical low back pain. He was evaluated on 3 separate occasions over a 3 year period. History, radiography, functional outcome studies, visual-numerical pain score, pain drawing, physical examination and surface electromyography were utilized in evaluating this patient. Intervention and Outcome: The two clinical interventions of spinal manipulative therapy (S.M.T.) had positive results in that the patient achieved an asymptomatic state and returned to his position of employment. The S.E.M.G. data collected during the industrial assessment, did not provide the outcome that the patient had anticipated. Conclusion: Surface electromyography is a useful clinical tool in the author’s decision-making process for the treatment of mechanical lower back pain. Therapeutic intervention by S.M.T., therapeutic exercises and rating risk factors were influenced by the S.E.M.G. findings.

  2. Myoelectric manifestation of muscle fatigue in repetitive work detected by means of miniaturized sEMG sensors.

    Science.gov (United States)

    Ranavolo, Alberto; Chini, Giorgia; Silvetti, Alessio; Mari, Silvia; Serrao, Mariano; Draicchio, Francesco

    2017-09-25

    Upper limb work-related musculoskeletal disorders have a 12-month prevalence ranging from 12 to 41% worldwide and can be partly caused by handling low loads at high frequency. The association between the myoelectric manifestation of elbow flexor muscle fatigue and occupational physical demand has never been investigated. It was hypothesized that an elbow flexor muscle fatigue index could be a valid risk indicator in handling low loads at high frequency. This study aims to measure the myoelectric manifestation of muscle fatigue of the three elbow flexor muscles during the execution of the work tasks in different risk conditions. Fifteen right-handed healthy adults were screened using a movement analysis laboratory consisting of optoelectronic, dynamometer and surface electromyographic systems. The main result indicates that the fatigue index calculated from the brachioradialis is sensitive to the interaction among risk classes, session and gender, and above all it is sensitive to the risk classes.

  3. Surface EMG and intra-socket force measurement to control a prosthetic device

    Science.gov (United States)

    Sanford, Joe; Patterson, Rita; Popa, Dan

    2015-06-01

    Surface electromyography (SEMG) has been shown to be a robust and reliable interaction method allowing for basic control of powered prosthetic devices. Research has shown a marked decrease in EMG-classification efficiency throughout activities of daily life due to socket shift and movement and fatigue as well as changes in degree of fit of the socket throughout the subject's lifetime. Users with the most severe levels of amputation require the most complex devices with the greatest number of degrees of freedom. Controlling complex dexterous devices with limited available inputs requires the addition of sensing and interaction modalities. However, the larger the amputation severity, the fewer viable SEMG sites are available as control inputs. Previous work reported the use of intra-socket pressure, as measured during wrist flexion and extension, and has shown that it is possible to control a powered prosthetic device with pressure sensors. In this paper, we present data correlations of SEMG data with intra-socket pressure data. Surface EMG sensors and force sensors were housed within a simulated prosthetic cuff fit to a healthy-limbed subject. EMG and intra-socket force data was collected from inside the cuff as a subject performed pre-defined grip motions with their dominant hand. Data fusion algorithms were explored and allowed a subject to use both intra-socket pressure and SEMG data as control inputs for a powered prosthetic device. This additional input modality allows for an improvement in input classification as well as information regarding socket fit through out activities of daily life.

  4. Hybrid neuromusculoskeletal modeling to best track joint moments using a balance between muscle excitations derived from electromyograms and optimization.

    Science.gov (United States)

    Sartori, Massimo; Farina, Dario; Lloyd, David G

    2014-11-28

    Current electromyography (EMG)-driven musculoskeletal models are used to estimate joint moments measured from an individual׳s extremities during dynamic movement with varying levels of accuracy. The main benefit is the underlying musculoskeletal dynamics is simulated as a function of realistic, subject-specific, neural-excitation patterns provided by the EMG data. The main disadvantage is surface EMG cannot provide information on deeply located muscles. Furthermore, EMG data may be affected by cross-talk, recording and post-processing artifacts that could adversely influence the EMG׳s information content. This limits the EMG-driven model׳s ability to calculate the multi-muscle dynamics and the resulting joint moments about multiple degrees of freedom. We present a hybrid neuromusculoskeletal model that combines calibration, subject-specificity, EMG-driven and static optimization methods together. In this, the joint moment tracking errors are minimized by balancing the information content extracted from the experimental EMG data and from that generated by a static optimization method. Using movement data from five healthy male subjects during walking and running we explored the hybrid model׳s best configuration to minimally adjust recorded EMGs and predict missing EMGs while attaining the best tracking of joint moments. Minimally adjusted and predicted excitations substantially improved the experimental joint moment tracking accuracy than current EMG-driven models. The ability of the hybrid model to predict missing muscle EMGs was also examined. The proposed hybrid model enables muscle-driven simulations of human movement while enforcing physiological constraints on muscle excitation patterns. This might have important implications for studying pathological movement for which EMG recordings are limited.

  5. The effect of manipulating root mean square window length and overlap on reliability, inter-individual variability, statistical significance and clinical relevance of electromyograms.

    Science.gov (United States)

    Mark Burden, Adrian; Lewis, Sandra Elizabeth; Willcox, Emma

    2014-12-01

    Numerous ways exist to process raw electromyograms (EMGs). However, the effect of altering processing methods on peak and mean EMG has seldom been investigated. The aim of this study was to investigate the effect of using different root mean square (RMS) window lengths and overlaps on the amplitude, reliability and inter-individual variability of gluteus maximus EMGs recorded during the clam exercise, and on the statistical significance and clinical relevance of amplitude differences between two exercise conditions. Mean and peak RMS of 10 repetitions from 17 participants were obtained using processing window lengths of 0.01, 0.15, 0.2, 0.25 and 1 s, with no overlap and overlaps of 25, 50 and 75% of window length. The effect of manipulating window length on reliability and inter-individual variability was greater for peak EMG (coefficient of variation [CV] window generally displaying the lowest variability. As a consequence, neither statistical significance nor clinical relevance (effect size [ES]) of mean EMG was affected by manipulation of window length. Statistical significance of peak EMG was more sensitive to changes in window length, with lower p-values generally being recorded for the 1 s window. As use of different window lengths has a greater effect on variability and statistical significance of the peak EMG, then clinicians should use the mean EMG. They should also be aware that use of different numbers of exercise repetitions and participants can have a greater effect on EMG parameters than length of processing window. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. An electromyogram-driven musculoskeletal model of the knee to predict in vivo joint contact forces during normal and novel gait patterns.

    Science.gov (United States)

    Manal, Kurt; Buchanan, Thomas S

    2013-02-01

    Computational models that predict internal joint forces have the potential to enhance our understanding of normal and pathological movement. Validation studies of modeling results are necessary if such models are to be adopted by clinicians to complement patient treatment and rehabilitation. The purposes of this paper are: (1) to describe an electromyogram (EMG)-driven modeling approach to predict knee joint contact forces, and (2) to evaluate the accuracy of model predictions for two distinctly different gait patterns (normal walking and medial thrust gait) against known values for a patient with a force recording knee prosthesis. Blinded model predictions and revised model estimates for knee joint contact forces are reported for our entry in the 2012 Grand Challenge to predict in vivo knee loads. The EMG-driven model correctly predicted that medial compartment contact force for the medial thrust gait increased despite the decrease in knee adduction moment. Model accuracy was high: the difference in peak loading was less than 0.01 bodyweight (BW) with an R(2 )= 0.92. The model also predicted lateral loading for the normal walking trial with good accuracy exhibiting a peak loading difference of 0.04 BW and an R(2 )= 0.44. Overall, the EMG-driven model captured the general shape and timing of the contact force profiles and with accurate input data the model estimated joint contact forces with sufficient accuracy to enhance the interpretation of joint loading beyond what is possible from data obtained from standard motion capture studies.

  7. Self-Recalibrating Surface EMG Pattern Recognition for Neuroprosthesis Control Based on Convolutional Neural Network

    Directory of Open Access Journals (Sweden)

    Xiaolong Zhai

    2017-07-01

    Full Text Available Hand movement classification based on surface electromyography (sEMG pattern recognition is a promising approach for upper limb neuroprosthetic control. However, maintaining day-to-day performance is challenged by the non-stationary nature of sEMG in real-life operation. In this study, we propose a self-recalibrating classifier that can be automatically updated to maintain a stable performance over time without the need for user retraining. Our classifier is based on convolutional neural network (CNN using short latency dimension-reduced sEMG spectrograms as inputs. The pretrained classifier is recalibrated routinely using a corrected version of the prediction results from recent testing sessions. Our proposed system was evaluated with the NinaPro database comprising of hand movement data of 40 intact and 11 amputee subjects. Our system was able to achieve ~10.18% (intact, 50 movement types and ~2.99% (amputee, 10 movement types increase in classification accuracy averaged over five testing sessions with respect to the unrecalibrated classifier. When compared with a support vector machine (SVM classifier, our CNN-based system consistently showed higher absolute performance and larger improvement as well as more efficient training. These results suggest that the proposed system can be a useful tool to facilitate long-term adoption of prosthetics for amputees in real-life applications.

  8. Discrete wavelet transform analysis of surface electromyography for the fatigue assessment of neck and shoulder muscles.

    Science.gov (United States)

    Chowdhury, Suman Kanti; Nimbarte, Ashish D; Jaridi, Majid; Creese, Robert C

    2013-10-01

    Assessment of neuromuscular fatigue is essential for early detection and prevention of risks associated with work-related musculoskeletal disorders. In recent years, discrete wavelet transform (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 the assessment of work-related neck and shoulder muscle fatigue 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 and shoulder muscle fatigue under dynamic repetitive conditions. Ten human participants performed 40min of fatiguing repetitive arm and neck exertions while SEMG data from the upper trapezius and sternocleidomastoid muscles were recorded. The ten of the most commonly used wavelet functions were used to conduct the DWT analysis. Spectral changes estimated using power of wavelet coefficients in the 12-23Hz frequency band showed the highest sensitivity to fatigue induced by the dynamic repetitive exertions. Although most of the wavelet functions tested in this study reasonably demonstrated the expected power trend with fatigue development and recovery, the overall performance of the "Rbio3.1" wavelet in terms of power estimation and statistical significance was better than the remaining nine wavelets. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Implementation of a Surface Electromyography-Based Upper Extremity Exoskeleton Controller Using Learning from Demonstration

    Directory of Open Access Journals (Sweden)

    Ho Chit Siu

    2018-02-01

    Full Text Available Upper-extremity exoskeletons have demonstrated potential as augmentative, assistive, and rehabilitative devices. Typical control of upper-extremity exoskeletons have relied on switches, force/torque sensors, and surface electromyography (sEMG, but these systems are usually reactionary, and/or rely on entirely hand-tuned parameters. sEMG-based systems may be able to provide anticipatory control, since they interface directly with muscle signals, but typically require expert placement of sensors on muscle bodies. We present an implementation of an adaptive sEMG-based exoskeleton controller that learns a mapping between muscle activation and the desired system state during interaction with a user, generating a personalized sEMG feature classifier to allow for anticipatory control. This system is robust to novice placement of sEMG sensors, as well as subdermal muscle shifts. We validate this method with 18 subjects using a thumb exoskeleton to complete a book-placement task. This learning-from-demonstration system for exoskeleton control allows for very short training times, as well as the potential for improvement in intent recognition over time, and adaptation to physiological changes in the user, such as those due to fatigue.

  10. Implementation of a Surface Electromyography-Based Upper Extremity Exoskeleton Controller Using Learning from Demonstration

    Science.gov (United States)

    Arenas, Ana M.; Sun, Tingxiao

    2018-01-01

    Upper-extremity exoskeletons have demonstrated potential as augmentative, assistive, and rehabilitative devices. Typical control of upper-extremity exoskeletons have relied on switches, force/torque sensors, and surface electromyography (sEMG), but these systems are usually reactionary, and/or rely on entirely hand-tuned parameters. sEMG-based systems may be able to provide anticipatory control, since they interface directly with muscle signals, but typically require expert placement of sensors on muscle bodies. We present an implementation of an adaptive sEMG-based exoskeleton controller that learns a mapping between muscle activation and the desired system state during interaction with a user, generating a personalized sEMG feature classifier to allow for anticipatory control. This system is robust to novice placement of sEMG sensors, as well as subdermal muscle shifts. We validate this method with 18 subjects using a thumb exoskeleton to complete a book-placement task. This learning-from-demonstration system for exoskeleton control allows for very short training times, as well as the potential for improvement in intent recognition over time, and adaptation to physiological changes in the user, such as those due to fatigue. PMID:29401754

  11. Support vectors machine classification of surface electromyography for non-invasive naturally controlled hand prostheses.

    Science.gov (United States)

    Moura, Karina O A; Favieiro, Gabriela W; Balbinot, Alexandre

    2016-08-01

    The scientific researches in human rehabilitation techniques have continually evolved to offer again the mobility and freedom lost to disability. Many systems managed by myoelectric signals intended to mimic the movement of the human arm still have results considered partial, which makes it subject of many researches. The use of Natural Interfaces Signal Processing methods makes possible to design systems capable of offering prosthesis in a more natural and intuitive way. This paper presents a study investigating the use of forearm surface electromyography (sEMG) signals for classification of specific movements of hand using 12 sEMG channels and support vector machine (SVM). The system acquired the sEMG signal using a virtual model as a visual stimulus in order to demonstrate to the volunteer the hand movements which must be replicated by them. The Root Mean Square (RMS) value feature is extracted of the signal and it serves as input data for the classification with SVM. The classification stage used three types of kernel functions (linear, polynomial, radial basis) for comparison of the results. The average accuracy reached for the classification of seventeen distinct movements of 83.7% was achieved using the SVM linear classifier, 80.8% was achieved using the SVM polynomial classifier and 85.1% was achieved using the SVM radial basis classifier.

  12. Analysis of progression of fatigue conditions in biceps brachii muscles using surface electromyography signals and complexity based features.

    Science.gov (United States)

    Karthick, P A; Makaram, Navaneethakrishna; Ramakrishnan, S

    2014-01-01

    Muscle fatigue is a neuromuscular condition where muscle performance decreases due to sustained or intense contraction. It is experienced by both normal and abnormal subjects. In this work, an attempt has been made to analyze the progression of muscle fatigue in biceps brachii muscles using surface electromyography (sEMG) signals. The sEMG signals are recorded from fifty healthy volunteers during dynamic contractions under well defined protocol. The acquired signals are preprocessed and segmented in to six equal parts for further analysis. The features, such as activity, mobility, complexity, sample entropy and spectral entropy are extracted from all six zones. The results are found showing that the extracted features except complexity feature have significant variations in differentiating non-fatigue and fatigue zone respectively. Thus, it appears that, these features are useful in automated analysis of various neuromuscular activities in normal and pathological conditions.

  13. A more precise, repeatable and diagnostic alternative to surface electromyography

    DEFF Research Database (Denmark)

    Harrison, Adrian P

    2018-01-01

    Acoustic myography (AMG) enables a detailed and accurate measurement of those muscles involved in a particular movement and is independent of electrical signals between the nerve and muscle, measuring solely muscle contractions, unlike surface electromyography (sEMG). With modern amplifiers...... and digital sound recording systems, measurements during physical activity both inside and outside a laboratory setting are now possible and accurate. Muscle sound gives a representation of the work of each muscle group during a complex movement, and under certain forms of movement even reveals both...

  14. Inter-day reliability of surface electromyography recordings of the lumbar part of erector spinae longissimus and trapezius descendens during box lifting

    OpenAIRE

    Brandt, Mikkel; Andersen, Lars Louis; Samani, Afshin; Jakobsen, Markus Due; Madeleine, Pascal

    2017-01-01

    Background Low back pain and neck-shoulder pain are the most reported types of work-related musculoskeletal disorders, and performing heavy lifting at work and working with trunk rotation increase the risk of developing work-related musculoskeletal disorders. Surface electromyography (sEMG) provides information about the electrical activity of muscles. Thus it has the potential to retrieve indirect information about the physical exposure of specific muscles of workers during their actual work...

  15. Surface electromyography based muscle fatigue detection using high-resolution time-frequency methods and machine learning algorithms.

    Science.gov (United States)

    Karthick, P A; Ghosh, Diptasree Maitra; Ramakrishnan, S

    2018-02-01

    Surface electromyography (sEMG) based muscle fatigue research is widely preferred in sports science and occupational/rehabilitation studies due to its noninvasiveness. However, these signals are complex, multicomponent and highly nonstationary with large inter-subject variations, particularly during dynamic contractions. Hence, time-frequency based machine learning methodologies can improve the design of automated system for these signals. In this work, the analysis based on high-resolution time-frequency methods, namely, Stockwell transform (S-transform), B-distribution (BD) and extended modified B-distribution (EMBD) are proposed to differentiate the dynamic muscle nonfatigue and fatigue conditions. The nonfatigue and fatigue segments of sEMG signals recorded from the biceps brachii of 52 healthy volunteers are preprocessed and subjected to S-transform, BD and EMBD. Twelve features are extracted from each method and prominent features are selected using genetic algorithm (GA) and binary particle swarm optimization (BPSO). Five machine learning algorithms, namely, naïve Bayes, support vector machine (SVM) of polynomial and radial basis kernel, random forest and rotation forests are used for the classification. The results show that all the proposed time-frequency distributions (TFDs) are able to show the nonstationary variations of sEMG signals. Most of the features exhibit statistically significant difference in the muscle fatigue and nonfatigue conditions. The maximum number of features (66%) is reduced by GA and BPSO for EMBD and BD-TFD respectively. The combination of EMBD- polynomial kernel based SVM is found to be most accurate (91% accuracy) in classifying the conditions with the features selected using GA. The proposed methods are found to be capable of handling the nonstationary and multicomponent variations of sEMG signals recorded in dynamic fatiguing contractions. Particularly, the combination of EMBD- polynomial kernel based SVM could be used to

  16. Reliability of surface EMG as an assessment tool for trunk activity and potential to determine neurorecovery in SCI.

    Science.gov (United States)

    Mitchell, M D; Yarossi, M B; Pierce, D N; Garbarini, E L; Forrest, G F

    2015-05-01

    Reliability and validity study. This study investigates the responsiveness and reliability of the brain motor control assessment (BMCA) as a standardized neurophysiological assessment tool to: (i) characterize trunk neural activity in neurologically-intact controls; (ii) measure and quantify neurorecovery of trunk after spinal cord injury (SCI). Kessler Foundation Research Center, West Orange, NJ. A standardized BMCA protocol was performed to measure surface electromyography (sEMG) recordings for seven bilateral trunk muscles on 15 able-bodied controls during six maneuvers (inhalation, exhalation, neck flexion, jendrassik, unilateral grip). Additionally, sEMG recordings were analyzed for one chronic SCI individual before electrical stimulation (ES), after ES of the lower extremities while supine, and after active stand training using body-weight support with bilateral ES. sEMG recordings were collected on bilateral erector spinae, internal and external obliques, upper and middle trapezius, biceps and triceps. For each maneuver a voluntary response index was calculated: incorporating the magnitude of sEMG signal and a similarity index (SI), which quantifies the distribution of activity across all muscles. Among all maneuvers, the SI presented reproducible assessment of trunk-motor function within (ICC: 0.860-0.997) and among (P⩾0.22) able-bodied individuals. In addition, potential changes were measured in a chronic SCI individual after undergoing two intensive ES protocols. The BMCA provides reproducible characterization of trunk activity in able-bodied individuals, lending credence for its use in neurophysiological assessment of motor control. Additionally, the BMCA as an assessment tool to measure neurorecovery in an individual with chronic SCI after intense ES interventions was demonstrated.

  17. Muscle-tendon units localization and activation level analysis based on high-density surface EMG array and NMF algorithm

    Science.gov (United States)

    Huang, Chengjun; Chen, Xiang; Cao, Shuai; Zhang, Xu

    2016-12-01

    Objective. Some skeletal muscles can be subdivided into smaller segments called muscle-tendon units (MTUs). The purpose of this paper is to propose a framework to locate the active region of the corresponding MTUs within a single skeletal muscle and to analyze the activation level varieties of different MTUs during a dynamic motion task. Approach. Biceps brachii and gastrocnemius were selected as targeted muscles and three dynamic motion tasks were designed and studied. Eight healthy male subjects participated in the data collection experiments, and 128-channel surface electromyographic (sEMG) signals were collected with a high-density sEMG electrode grid (a grid consists of 8 rows and 16 columns). Then the sEMG envelopes matrix was factorized into a matrix of weighting vectors and a matrix of time-varying coefficients by nonnegative matrix factorization algorithm. Main results. The experimental results demonstrated that the weightings vectors, which represent invariant pattern of muscle activity across all channels, could be used to estimate the location of MTUs and the time-varying coefficients could be used to depict the variation of MTUs activation level during dynamic motion task. Significance. The proposed method provides one way to analyze in-depth the functional state of MTUs during dynamic tasks and thus can be employed on multiple noteworthy sEMG-based applications such as muscle force estimation, muscle fatigue research and the control of myoelectric prostheses. This work was supported by the National Nature Science Foundation of China under Grant 61431017 and 61271138.

  18. Extração de características e classificação de sinais sEMG aplicados a uma prótese de mão virtual

    OpenAIRE

    Tello, Richard Junior Manuel Godinez

    2013-01-01

    Este trabalho apresenta a classificação de tarefas motoras, através da eletromiografia de superfície (sEMG), para controlar uma mão prostética para reabilitação de amputados. Dois tipos de classificadores são comparados: k-vizinhos mais próximos (k-NN) e Bayesiano (Análise Discriminante). As tarefas motoras são divididas em quatro grupos correlacionados. Os voluntários desta pesquisa foram pessoas saudáveis (sem amputação), e várias análises de cada um dos sinais foram realizadas. Para o anal...

  19. Functional connectivity between core and shoulder muscles increases during isometric endurance contractions in judo competitors

    DEFF Research Database (Denmark)

    Kawczyński, Adam; Samani, Afshin; Mroczek, Dariusz

    2015-01-01

    Purpose: The aim of this study was to assess the surface electromyogram (SEMG) changes within and between muscles of the torso and shoulder region during static endurance contraction in elite judokas. We hypothesized an increased functional connectivity of muscles from the shoulder and torso...... endurance contraction consisting of bilateral arm abduction at 90°. The normalized mutual information (NMI) was computed between muscle pairs as an index indicating functional connectivity. Results: The NMIs increased significantly during endurance test for 10 of the 15 muscle pairs (P ... : We concluded that the increases in NMIs highlighted functional changes in the interplay between core and shoulder muscles during an endurance contraction in elite judokas....

  20. Evaluating the Training Effects of Two Swallowing Rehabilitation Therapies Using Surface Electromyography--Chin Tuck Against Resistance (CTAR) Exercise and the Shaker Exercise.

    Science.gov (United States)

    Sze, Wei Ping; Yoon, Wai Lam; Escoffier, Nicolas; Rickard Liow, Susan J

    2016-04-01

    In this study, the efficacy of two dysphagia interventions, the Chin Tuck against Resistance (CTAR) and Shaker exercises, were evaluated based on two principles in exercise science-muscle-specificity and training intensity. Both exercises were developed to strengthen the suprahyoid muscles, whose contractions facilitate the opening of the upper esophageal sphincter, thereby improving bolus transfer. Thirty-nine healthy adults performed two trials of both exercises in counter-balanced order. Surface electromyography (sEMG) recordings were simultaneously collected from suprahyoid muscle group and sternocleidomastoid muscle during the exercises. Converging results using sEMG amplitude analyses suggested that the CTAR was more specific in targeting the suprahyoid muscles than the Shaker exercise. Fatigue analyses on sEMG signals further indicated that the suprahyoid muscle group were equally or significantly fatigued (depending on metric), when participants carried out CTAR compared to the Shaker exercise. Importantly, unlike during Shaker exercise, the sternocleidomastoid muscles were significantly less activated and fatigued during CTAR. Lowering the chin against resistance is therefore sufficiently specific and intense to fatigue the suprahyoid muscles.

  1. A Novel Hybrid Model for Drawing Trace Reconstruction from Multichannel Surface Electromyographic Activity.

    Science.gov (United States)

    Chen, Yumiao; Yang, Zhongliang

    2017-01-01

    Recently, several researchers have considered the problem of reconstruction of handwriting and other meaningful arm and hand movements from surface electromyography (sEMG). Although much progress has been made, several practical limitations may still affect the clinical applicability of sEMG-based techniques. In this paper, a novel three-step hybrid model of coordinate state transition, sEMG feature extraction and gene expression programming (GEP) prediction is proposed for reconstructing drawing traces of 12 basic one-stroke shapes from multichannel surface electromyography. Using a specially designed coordinate data acquisition system, we recorded the coordinate data of drawing traces collected in accordance with the time series while 7-channel EMG signals were recorded. As a widely-used time domain feature, Root Mean Square (RMS) was extracted with the analysis window. The preliminary reconstruction models can be established by GEP. Then, the original drawing traces can be approximated by a constructed prediction model. Applying the three-step hybrid model, we were able to convert seven channels of EMG activity recorded from the arm muscles into smooth reconstructions of drawing traces. The hybrid model can yield a mean accuracy of 74% in within-group design (one set of prediction models for all shapes) and 86% in between-group design (one separate set of prediction models for each shape), averaged for the reconstructed x and y coordinates. It can be concluded that it is feasible for the proposed three-step hybrid model to improve the reconstruction ability of drawing traces from sEMG.

  2. Comparison of regression models for estimation of isometric wrist joint torques using surface electromyography

    Directory of Open Access Journals (Sweden)

    Menon Carlo

    2011-09-01

    Full Text Available Abstract Background Several regression models have been proposed for estimation of isometric joint torque using surface electromyography (SEMG signals. Common issues related to torque estimation models are degradation of model accuracy with passage of time, electrode displacement, and alteration of limb posture. This work compares the performance of the most commonly used regression models under these circumstances, in order to assist researchers with identifying the most appropriate model for a specific biomedical application. Methods Eleven healthy volunteers participated in this study. A custom-built rig, equipped with a torque sensor, was used to measure isometric torque as each volunteer flexed and extended his wrist. SEMG signals from eight forearm muscles, in addition to wrist joint torque data were gathered during the experiment. Additional data were gathered one hour and twenty-four hours following the completion of the first data gathering session, for the purpose of evaluating the effects of passage of time and electrode displacement on accuracy of models. Acquired SEMG signals were filtered, rectified, normalized and then fed to models for training. Results It was shown that mean adjusted coefficient of determination (Ra2 values decrease between 20%-35% for different models after one hour while altering arm posture decreased mean Ra2 values between 64% to 74% for different models. Conclusions Model estimation accuracy drops significantly with passage of time, electrode displacement, and alteration of limb posture. Therefore model retraining is crucial for preserving estimation accuracy. Data resampling can significantly reduce model training time without losing estimation accuracy. Among the models compared, ordinary least squares linear regression model (OLS was shown to have high isometric torque estimation accuracy combined with very short training times.

  3. Analysis of Muscle Fatigue Progression using Cyclostationary Property of Surface Electromyography Signals.

    Science.gov (United States)

    Karthick, P A; Venugopal, G; Ramakrishnan, S

    2016-01-01

    Analysis of neuromuscular fatigue finds various applications ranging from clinical studies to biomechanics. Surface electromyography (sEMG) signals are widely used for these studies due to its non-invasiveness. During cyclic dynamic contractions, these signals are nonstationary and cyclostationary. In recent years, several nonstationary methods have been employed for the muscle fatigue analysis. However, cyclostationary based approach is not well established for the assessment of muscle fatigue. In this work, cyclostationarity associated with the biceps brachii muscle fatigue progression is analyzed using sEMG signals and Spectral Correlation Density (SCD) functions. Signals are recorded from fifty healthy adult volunteers during dynamic contractions under a prescribed protocol. These signals are preprocessed and are divided into three segments, namely, non-fatigue, first muscle discomfort and fatigue zones. Then SCD is estimated using fast Fourier transform accumulation method. Further, Cyclic Frequency Spectral Density (CFSD) is calculated from the SCD spectrum. Two features, namely, cyclic frequency spectral area (CFSA) and cyclic frequency spectral entropy (CFSE) are proposed to study the progression of muscle fatigue. Additionally, degree of cyclostationarity (DCS) is computed to quantify the amount of cyclostationarity present in the signals. Results show that there is a progressive increase in cyclostationary during the progression of muscle fatigue. CFSA shows an increasing trend in muscle fatiguing contraction. However, CFSE shows a decreasing trend. It is observed that when the muscle progresses from non-fatigue to fatigue condition, the mean DCS of fifty subjects increases from 0.016 to 0.99. All the extracted features found to be distinct and statistically significant in the three zones of muscle contraction (p < 0.05). It appears that these SCD features could be useful in the automated analysis of sEMG signals for different neuromuscular conditions.

  4. Assessment of Diaphragm and External Intercostals Fatigue from Surface EMG using Cervical Magnetic Stimulation

    Directory of Open Access Journals (Sweden)

    Ya-Ju Chang

    2008-03-01

    Full Text Available This study was designed: (1 to test the reliability of surface electromyography (sEMG recording of the diaphragm and external intercostals contractions response to cervical magnetic stimulation (CMS, (2 to examine the amount and the types of inspiratory muscle fatigue that developed after maximum voluntary ventilation (MVV maneuvers.Ten male college students without physical disability (22.1±2.0 years old participated in the study and each completed a control (quiet breathing trial and a fatigue (MVV maneuvers trial sequentially. In the quiet breathing trial, the subjects maintained quiet breathing for five minutes. The subjects performed five maximal static inspiratory efforts and received five CMS before and after the quiet breathing. In the MVV trial, subjects performed five maximal inspiratory efforts and received five CMS before, immediately after, and ten minutes after two sets of MVV maneuvers performed five minutes apart. Maximal inspiratory pressure (PImax, sEMG of diaphragm and external intercostals during maximal static inspiratory efforts and during CMS were recorded. In the quiet breathing trial, high intraclass correlation coefficients (ICC=0.95-0.99 were observed in all the variables. In the MVV trial, the PImax, the EMG amplitude and the median power frequency during maximal static inspiratory efforts significantly decreased in both the diaphragm and the external intercostals immediately after the MVV maneuvers Sensors 2008, 8 2175 (P 0.05. It is concluded that the sEMG recordings of the diaphragm during maximal static inspiratory efforts and in response to CMS allow reproducible sequential assessment of diaphragm contractility. MVV maneuvers resulted in inspiratory muscles fatigue, possibly central fatigue.

  5. Surface EMG-based Sketching Recognition Using Two Analysis Windows and Gene Expression Programming

    Science.gov (United States)

    Yang, Zhongliang; Chen, Yumiao

    2016-01-01

    Sketching is one of the most important processes in the conceptual stage of design. Previous studies have relied largely on the analyses of sketching process and outcomes; whereas surface electromyographic (sEMG) signals associated with sketching have received little attention. In this study, we propose a method in which 11 basic one-stroke sketching shapes are identified from the sEMG signals generated by the forearm and upper arm muscles from 4 subjects. Time domain features such as integrated electromyography, root mean square and mean absolute value were extracted with analysis windows of two length conditions for pattern recognition. After reducing data dimensionality using principal component analysis, the shapes were classified using Gene Expression Programming (GEP). The performance of the GEP classifier was compared to the Back Propagation neural network (BPNN) and the Elman neural network (ENN). Feature extraction with the short analysis window (250 ms with a 250 ms increment) improved the recognition rate by around 6.4% averagely compared with the long analysis window (2500 ms with a 2500 ms increment). The average recognition rate for the eleven basic one-stroke sketching patterns achieved by the GEP classifier was 96.26% in the training set and 95.62% in the test set, which was superior to the performance of the BPNN and ENN classifiers. The results show that the GEP classifier is able to perform well with either length of the analysis window. Thus, the proposed GEP model show promise for recognizing sketching based on sEMG signals. PMID:27790083

  6. Effective Low-Power Wearable Wireless Surface EMG Sensor Design Based on Analog-Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Mohammadreza Balouchestani

    2014-12-01

    Full Text Available Surface Electromyography (sEMG is a non-invasive measurement process that does not involve tools and instruments to break the skin or physically enter the body to investigate and evaluate the muscular activities produced by skeletal muscles. The main drawbacks of existing sEMG systems are: (1 they are not able to provide real-time monitoring; (2 they suffer from long processing time and low speed; (3 they are not effective for wireless healthcare systems because they consume huge power. In this work, we present an analog-based Compressed Sensing (CS architecture, which consists of three novel algorithms for design and implementation of wearable wireless sEMG bio-sensor. At the transmitter side, two new algorithms are presented in order to apply the analog-CS theory before Analog to Digital Converter (ADC. At the receiver side, a robust reconstruction algorithm based on a combination of ℓ1-ℓ1-optimization and Block Sparse Bayesian Learning (BSBL framework is presented to reconstruct the original bio-signals from the compressed bio-signals. The proposed architecture allows reducing the sampling rate to 25% of Nyquist Rate (NR. In addition, the proposed architecture reduces the power consumption to 40%, Percentage Residual Difference (PRD to 24%, Root Mean Squared Error (RMSE to 2%, and the computation time from 22 s to 9.01 s, which provide good background for establishing wearable wireless healthcare systems. The proposed architecture achieves robust performance in low Signal-to-Noise Ratio (SNR for the reconstruction process.

  7. Can methylphenidate objectively provide relief in patients with uncontrolled blepharospasm? A pilot study using surface electromyography.

    Science.gov (United States)

    Price, Kristina M; Ramey, Nicholas A; Richard, Michael J; Woodward, Donald J; Woodward, Julie A

    2010-01-01

    To determine whether there is an objective benefit to prescribing Ritalin for patients with uncontrolled blepharospasm exists. Seven subjects with benign essential blepharospasm, who were being treated with botulinum toxin injections and Ritalin LA, were recruited for this pilot study. Patients were asked to participate during the period of time when symptoms were beginning to return. Subjects underwent video and surface electromyography (sEMG) monitoring before and 2 hours after the administration of Ritalin. Mean sEMG potential for each eye was compared before and after the administration of Ritalin. Subjects also rated their disability based on a previously developed and reproducible blepharospasm functional disability scale. Functional Disability Scores were compared, and post-Ritalin treatment benefit was determined. The mean voltage of the sEMG was lower in 13 of 14 eyes after the administration of Ritalin. For the right eye, the voltage decreased by 50% (106.4 ± 13.6 mV to 52.7 ± 7.1 mV, p = 0.015), and for the left eye, by 31% (81.9 ± 9.7 mV to 56.6 ± 6.1 mV, p = 0.031). The Functional Disability Scores were also lower after the administration of Ritalin than before (p = 0.016). A significant decrease in mean voltage after the administration of Ritalin was found in this preselected group of patients. Subjective improvement with decreased disability and increased functional benefit was also found in all subjects. Based on the results of this study, a randomized, controlled study comparing Ritalin versus placebo is needed to determine whether Ritalin should be routinely prescribed for benign essential blepharospasm during the symptomatic window period.

  8. SURFACE ELECTROMYOGRAPHY IN BIOMECHANICS: APPLICATIONS AND SIGNAL ANALYSIS ASPECTS

    Directory of Open Access Journals (Sweden)

    DEAK GRAłIELA-FLAVIA

    2009-12-01

    Full Text Available Surface electromyography (SEMG is a technique for detecting and recording the electrical activity of the muscles using surface electrodes. The EMG signal is used in biomechanics mainly as an indicator of the initiation of muscle activation, as an indicator of the force produced by a contracting muscle, and as an index ofthe fatigue occurring within a muscle. EMG, used as a method of investigation, can tell us if the muscle is active or not, if the muscle is more or less active, when it is on or off, how much active is it, and finally, if it fatigues.The purpose of this article is to discuss some specific EMG signal analysis aspects with emphasis on comparison type analysis and frequency fatigue analysis.

  9. Application of advanced biomechanical methods in studying low back pain – recent development in estimation of lower back loads and large-array surface electromyography and findings

    Directory of Open Access Journals (Sweden)

    Bazrgari B

    2017-07-01

    Full Text Available Babak Bazrgari,1 Ting Xia2 1F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY, 2Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, IA, USA Abstract: Low back pain (LBP is a major public health problem and the leading disabling musculoskeletal disorder globally. A number of biomechanical methods using kinematic, kinetic and/or neuromuscular approaches have been used to study LBP. In this narrative review, we report recent developments in two biomechanical methods: estimation of lower back loads and large-array surface electromyography (LA-SEMG and the findings associated with LBP. The ability to estimate lower back loads is very important for the prevention and the management of work-related low back injuries based on the mechanical loading model as one category of LBP classification. The methods used for estimation of lower back loads vary from simple rigid link-segment models to sophisticated, optimization-based finite element models. In general, reviewed reports of differences in mechanical loads experienced in lower back tissues between patients with LBP and asymptomatic individuals are not consistent. Such lack of consistency is primarily due to differences in activities under which lower back mechanical loads were investigated as well as heterogeneity of patient populations. The ability to examine trunk neuromuscular behavior is particularly relevant to the motor control model, another category of LBP classification. LA-SEMG not only is noninvasive but also provides spatial resolution within and across muscle groups. Studies using LA-SEMG showed that healthy individuals exhibit highly organized, symmetric back muscle activity patterns, suggesting an orderly recruitment of muscle fibers. In contrast, back muscle activity patterns in LBP patients are asymmetric or multifocal, suggesting lack of orderly muscle recruitment. LA-SEMG was also shown capable of

  10. Comparison between sEMG and force as control interfaces to support planar arm movements in adults with Duchenne: a feasibility study

    NARCIS (Netherlands)

    Lobo-Prat, J.; Nizamis, K.; Janssen, M.M.H.P.; Keemink, A.Q.L.; Veltink, P.H.; Koopman, B.; Stienen, A.H.A.

    2017-01-01

    BACKGROUND: Adults with Duchenne muscular dystrophy (DMD) can benefit from devices that actively support their arm function. A critical component of such devices is the control interface as it is responsible for the human-machine interaction. Our previous work indicated that surface electromyography

  11. Oynophagia in patients after dental extraction: surface electromyography study

    Directory of Open Access Journals (Sweden)

    Nahlieli Oded

    2006-10-01

    Full Text Available Abstract Objectives Surface electromyographic (sEMG studies were performed on 40 adult patients following extraction of lower third and second molars to research the approach and limitations of sEMG evaluation of their odynophagia complaints. Methods Parameters evaluated during swallowing and drinking include the timing, number of swallows per 100 cc of water, and range (amplitude of EMG activity of m. masseter, infrahyoid and submental-submandibular group. The above mentioned variables (mean + standard deviation were measured for the group of dental patients (n = 40 and control group of healthy adults (n = 40. Results The duration of swallows and drinking in all tests showed increase in dental patients' group, in which this tendency is statistically significant. There was no statistically significant difference between male and female adults' duration and amplitude of muscle activity during continuous drinking in both groups (p = 0.05. The mean of electric activity (in μV of m. masseter was significantly lower in the dental patients' group in comparison with control group. The electric activity of submental-submandimular and infrahyoid muscle groups was the same in both groups. Conclusion Surface EMG of swallowing is a simple and reliable noninvasive method for evaluation of odynophagia/dysphagia complaints following dental extraction with low level of discomfort of the examination. The surface EMG studies prove that dysphagia following dental extraction and molar surgery has oral origin, does not affect pharingeal segment and submental-submandibular muscle group. This type of dysphagia has clear EMG signs: increased duration of single swallow, longer drinking time, low range of electric activity of m. masseter, normal range of activity of submental-submandibular muscle group, and the "dry swalow" aftereffect. The data can be used for evaluation of complaints and symptoms, as well as for comparison purposes in pre- and postoperative stages and

  12. Normalised Mutual Information of High-Density Surface Electromyography during Muscle Fatigue

    Directory of Open Access Journals (Sweden)

    Adrian Bingham

    2017-12-01

    Full Text Available This study has developed a technique for identifying the presence of muscle fatigue based on the spatial changes of the normalised mutual information (NMI between multiple high density surface electromyography (HD-sEMG channels. Muscle fatigue in the tibialis anterior (TA during isometric contractions at 40% and 80% maximum voluntary contraction levels was investigated in ten healthy participants (Age range: 21 to 35 years; Mean age = 26 years; Male = 4, Female = 6. HD-sEMG was used to record 64 channels of sEMG using a 16 by 4 electrode array placed over the TA. The NMI of each electrode with every other electrode was calculated to form an NMI distribution for each electrode. The total NMI for each electrode (the summation of the electrode’s NMI distribution highlighted regions of high dependence in the electrode array and was observed to increase as the muscle fatigued. To summarise this increase, a function, M(k, was defined and was found to be significantly affected by fatigue and not by contraction force. The technique discussed in this study has overcome issues regarding electrode placement and was used to investigate how the dependences between sEMG signals within the same muscle change spatially during fatigue.

  13. Effectiveness of the Wavelet Transform on the Surface EMG to Understand the Muscle Fatigue During Walk

    Science.gov (United States)

    Hussain, M. S.; Mamun, Md.

    2012-01-01

    Muscle fatigue is the decline in ability of a muscle to create force. Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. During a sustained muscle contraction, the power spectrum of the EMG shifts towards lower frequencies. These effects are due to muscle fatigue. Muscle fatigue is often a result of unhealthy work practice. In this research, the effectiveness of the wavelet transform applied to the surface EMG (SEMG) signal as a means of understanding muscle fatigue during walk is presented. Power spectrum and bispectrum analysis on the EMG signal getting from right rectus femoris muscle is executed utilizing various wavelet functions (WFs). It is possible to recognize muscle fatigue appreciably with the proper choice of the WF. The outcome proves that the most momentous changes in the EMG power spectrum are symbolized by WF Daubechies45. Moreover, this research has compared bispectrum properties to the other WFs. To determine muscle fatigue during gait, Daubechies45 is used in this research to analyze the SEMG signal.

  14. Surface electromyography based muscle fatigue analysis for stroke patients at different Brunnstrom stages.

    Science.gov (United States)

    Yinjun Tu; Zhe Zhang; Xudong Gu; Qiang Fang

    2016-08-01

    Muscle fatigue analysis has been an important topic in sport and rehabilitation medicine due to its role in muscle performance evaluation and pathology investigation. This paper proposes a surface electromyography (sEMG) based muscle fatigue analysis approach which was specifically designed for stroke rehabilitation applications. 14 stroke patients from 5 different Brunnstrom recovery stage groups were involved in the experiment and features including median frequency and mean power frequency were extracted from the collected sEMG samples for investigation. After signal decomposition, the decline of motor unit firing rate of patients from different groups had also been studied. Statistically significant presence of fatigue had been observed in deltoideus medius and extensor digitorum communis of patients at early recovery stages (P0.01). It had also been discovered that the motor unit firing frequency declines with a range positively correlated to the recovery stage during repetitive movements. Based on the experiment result, it can be verified that as the recovery stage increases, the central nervous system's control ability strengthens and the patient motion becomes more stable and resistive to fatigue.

  15. Surface EMG to assess arm function in boys with DMD: a pilot study.

    Science.gov (United States)

    Janssen, Mariska M H P; Harlaar, Jaap; de Groot, Imelda J M

    2015-04-01

    Preserving functional abilities of the upper extremities is a major concern in boys with Duchenne Muscular Dystrophy (DMD). To assess disease progression and treatments, good knowledge on arm function in boys with DMD is essential. Therefore, feasibility and validity of the use of surface electromyography (sEMG) to assess arm function in boys with DMD was examined. Five boys with DMD and 6 age-matched controls participated in this study. Single joint movements and ADL activities were examined while recording sEMG of main shoulder and elbow muscles. All boys with DMD and controls were able to perform the non standardized movements of the measurement protocol, however one boy with DMD was not able to perform all the standardized movements. Boys with DMD used significantly more of their maximal muscle capacity for all muscles to conduct movements compared to controls. The measurement protocol was feasible to assess arm function in boys with DMD. This tool was able to discriminate between DMD patients and controls. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Does Heel Height Cause Imbalance during Sit-to-Stand Task: Surface EMG Perspective

    Directory of Open Access Journals (Sweden)

    Ganesh R. Naik

    2017-08-01

    Full Text Available The purpose of this study was to determine whether electromyography (EMG muscle activities around the knee differ during sit-to-stand (STS and returning task for females wearing shoes with different heel heights. Sixteen healthy young women (age = 25.2 ± 3.9 years, body mass index = 20.8 ± 2.7 kg/m2 participated in this study. Electromyography signals were recorded from the two muscles, vastus medialis (VM and vastus lateralis (VL that involve in the extension of knee. The participants wore shoes with five different heights, including 4, 6, 8, 10, and 12 cm. Surface electromyography (sEMG data were acquired during STS and stand-to-sit-returning (STSR tasks. The data was filtered using a fourth order Butterworth (band pass filter of 20–450 Hz frequency range. For each heel height, we extracted median frequency (MDF and root mean square (RMS features to measure sEMG activities between VM and VL muscles. The experimental results (based on MDF and RMS-values indicated that there is imbalance between vasti muscles for more elevated heels. The results are also quantified with statistical measures. The study findings suggest that there would be an increased likelihood of knee imbalance and fatigue with regular usage of high heel shoes (HHS in women.

  17. Reliability of surface electromyography timing parameters in gait in cervical spondylotic myelopathy.

    LENUS (Irish Health Repository)

    Malone, Ailish

    2012-02-01

    The aims of this study were to validate a computerised method to detect muscle activity from surface electromyography (SEMG) signals in gait in patients with cervical spondylotic myelopathy (CSM), and to evaluate the test-retest reliability of the activation times designated by this method. SEMG signals were recorded from rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (MG), during gait in 12 participants with CSM on two separate test days. Four computerised activity detection methods, based on the Teager-Kaiser Energy Operator (TKEO), were applied to a subset of signals and compared to visual interpretation of muscle activation. The most accurate method was then applied to all signals for evaluation of test-retest reliability. A detection method based on a combined slope and amplitude threshold showed the highest agreement (87.5%) with visual interpretation. With respect to reliability, the standard error of measurement (SEM) of the timing of RF, TA and MG between test days was 5.5% stride duration or less, while the SEM of BF was 9.4%. The timing parameters of RF, TA and MG designated by this method were considered sufficiently reliable for use in clinical practice, however the reliability of BF was questionable.

  18. Effect of the Enveloppe Linguale Nocturne on atypical swallowing: surface electromyography and computerised postural test evaluation.

    Science.gov (United States)

    Ciavarella, D; Mastrovincenzo, M; Sabatucci, A; Parziale, V; Chimenti, C

    2010-09-01

    Swallowing is a neuromuscular mechanism regulated by many nervous reflex arcs. Persistence of child swallowing at the end of dental eruption is called atypical swallowing (AS). This condition is related to a dysfunction of vertical maxillary growth called open bite. The authors treated this malocclusion with the Enveloppe Linguale Nocturne (ELN), or tongue positioner, created by Dr. Bonnet. The aim of this work is to evaluate the effect of ELN on swallowing and the postural variation obtained by its use. Seven patients affected by AS were evaluated. Surface Electromyography (sEMG) testing was performed on each patient with different tongue positions, and swallowing was evaluated with and without the ELN. A surface Electromyograph (Biopack) with 8 channels was used (4 channels for the right muscles and 4 for the left) on 4 groups of muscles: temporals, masseters (MM), submental (SUB) and sternocleidmastoids. On each patient a postural test using a computerised Postural test (Lizard) was also performed. Statistical analysis was done using the Graph pad Instat 3 both for sEMG activity and for computerised postural analysis. All seven subjects had different results in the sEMG and footrest tests. The sEMG test results indicated that muscle activation and swallowing duration varied greatly with the use of ELN, with a reduction of time of swallow act (p = 0.002) and variation in contraction of muscles. Mean MM activation was higher without ELN than in tests performed with the appliance (p = 0.002). Mean SUB activation was higher with than without ELN (p = 0.0033). ELN has a therapeutic effect on posture too. Computerised postural test without device showed in all patients an alteration of barycentre as well as an elevated oscillatory record (A mmq; V mms). With ELN footrest kilogram difference (p = 0.0110), Oscillatory Area (P = 0.0102) and velocity of oscillation (P = 0.0102) presented a great reduction in respect to patients record without ELN. With ELN the tongue

  19. FEATURE EXTRACTION FOR EMG BASED PROSTHESES CONTROL

    Directory of Open Access Journals (Sweden)

    R. Aishwarya

    2013-01-01

    Full Text Available The control of prosthetic limb would be more effective if it is based on Surface Electromyogram (SEMG signals from remnant muscles. The analysis of SEMG signals depend on a number of factors, such as amplitude as well as time- and frequency-domain properties. Time series analysis using Auto Regressive (AR model and Mean frequency which is tolerant to white Gaussian noise are used as feature extraction techniques. EMG Histogram is used as another feature vector that was seen to give more distinct classification. The work was done with SEMG dataset obtained from the NINAPRO DATABASE, a resource for bio robotics community. Eight classes of hand movements hand open, hand close, Wrist extension, Wrist flexion, Pointing index, Ulnar deviation, Thumbs up, Thumb opposite to little finger are taken into consideration and feature vectors are extracted. The feature vectors can be given to an artificial neural network for further classification in controlling the prosthetic arm which is not dealt in this paper.

  20. EOG-sEMG Human Interface for Communication.

    Science.gov (United States)

    Tamura, Hiroki; Yan, Mingmin; Sakurai, Keiko; Tanno, Koichi

    2016-01-01

    The aim of this study is to present electrooculogram (EOG) and surface electromyogram (sEMG) signals that can be used as a human-computer interface. Establishing an efficient alternative channel for communication without overt speech and hand movements is important for increasing the quality of life for patients suffering from amyotrophic lateral sclerosis, muscular dystrophy, or other illnesses. In this paper, we propose an EOG-sEMG human-computer interface system for communication using both cross-channels and parallel lines channels on the face with the same electrodes. This system could record EOG and sEMG signals as "dual-modality" for pattern recognition simultaneously. Although as much as 4 patterns could be recognized, dealing with the state of the patients, we only choose two classes (left and right motion) of EOG and two classes (left blink and right blink) of sEMG which are easily to be realized for simulation and monitoring task. From the simulation results, our system achieved four-pattern classification with an accuracy of 95.1%.

  1. Effects of Force Load, Muscle Fatigue, and Magnetic Stimulation on Surface Electromyography during Side Arm Lateral Raise Task: A Preliminary Study with Healthy Subjects

    Directory of Open Access Journals (Sweden)

    Liu Cao

    2017-01-01

    Full Text Available The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low-frequency (ELF magnetic stimulation on surface electromyography (SEMG signal features during side arm lateral raise task. SEMG signals were recorded from 18 healthy subjects on the anterior deltoid using a BIOSEMI ActiveTwo system during side lateral raise task (with the right arm 90 degrees away from the body with three different loads on the forearm (0 kg, 1 kg, and 3 kg; their order was randomized between subjects. The arm maintained the loads until the subject felt exhausted. The first 10 s recording for each load was regarded as nonfatigue status and the last 10 s before the subject was exhausted was regarded as fatigue status. The subject was then given a five-minute resting between different loads. Two days later, the same experiment was repeated on every subject, and this time the ELF magnetic stimulation was applied to the subject’s deltoid muscle during the five-minute rest period. Three commonly used SEMG features, root mean square (RMS, median frequency (MDF, and sample entropy (SampEn, were analyzed and compared between different loads, nonfatigue/fatigue status, and ELF stimulation and no stimulation. Variance analysis results showed that the effect of force load on RMS was significant (p0.05. In comparison with nonfatigue status, for all the different force loads with and without ELF stimulation, RMS was significantly larger at fatigue (all p<0.001 and MDF and SampEn were significantly smaller (all p<0.001.

  2. Effects of Force Load, Muscle Fatigue, and Magnetic Stimulation on Surface Electromyography during Side Arm Lateral Raise Task: A Preliminary Study with Healthy Subjects.

    Science.gov (United States)

    Cao, Liu; Wang, Ying; Hao, Dongmei; Rong, Yao; Yang, Lin; Zhang, Song; Zheng, Dingchang

    2017-01-01

    The aim of this study was to quantitatively investigate the effects of force load, muscle fatigue, and extremely low-frequency (ELF) magnetic stimulation on surface electromyography (SEMG) signal features during side arm lateral raise task. SEMG signals were recorded from 18 healthy subjects on the anterior deltoid using a BIOSEMI ActiveTwo system during side lateral raise task (with the right arm 90 degrees away from the body) with three different loads on the forearm (0 kg, 1 kg, and 3 kg; their order was randomized between subjects). The arm maintained the loads until the subject felt exhausted. The first 10 s recording for each load was regarded as nonfatigue status and the last 10 s before the subject was exhausted was regarded as fatigue status. The subject was then given a five-minute resting between different loads. Two days later, the same experiment was repeated on every subject, and this time the ELF magnetic stimulation was applied to the subject's deltoid muscle during the five-minute rest period. Three commonly used SEMG features, root mean square (RMS), median frequency (MDF), and sample entropy (SampEn), were analyzed and compared between different loads, nonfatigue/fatigue status, and ELF stimulation and no stimulation. Variance analysis results showed that the effect of force load on RMS was significant ( p 0.05). In comparison with nonfatigue status, for all the different force loads with and without ELF stimulation, RMS was significantly larger at fatigue (all p < 0.001) and MDF and SampEn were significantly smaller (all p < 0.001).

  3. Robust Features Of Surface Electromyography Signal

    International Nuclear Information System (INIS)

    Sabri, M I; Miskon, M F; Yaacob, M R

    2013-01-01

    Nowadays, application of robotics in human life has been explored widely. Robotics exoskeleton system are one of drastically areas in recent robotic research that shows mimic impact in human life. These system have been developed significantly to be used for human power augmentation, robotics rehabilitation, human power assist, and haptic interaction in virtual reality. This paper focus on solving challenges in problem using neural signals and extracting human intent. Commonly, surface electromyography signal (sEMG) are used in order to control human intent for application exoskeleton robot. But the problem lies on difficulty of pattern recognition of the sEMG features due to high noises which are electrode and cable motion artifact, electrode noise, dermic noise, alternating current power line interface, and other noise came from electronic instrument. The main objective in this paper is to study the best features of electromyography in term of time domain (statistical analysis) and frequency domain (Fast Fourier Transform).The secondary objectives is to map the relationship between torque and best features of muscle unit activation potential (MaxPS and RMS) of biceps brachii. This project scope use primary data of 2 male sample subject which using same dominant hand (right handed), age between 20–27 years old, muscle diameter 32cm to 35cm and using single channel muscle (biceps brachii muscle). The experiment conduct 2 times repeated task of contraction and relaxation of biceps brachii when lifting different load from no load to 3kg with ascending 1kg The result shows that Fast Fourier Transform maximum power spectrum (MaxPS) has less error than mean value of reading compare to root mean square (RMS) value. Thus, Fast Fourier Transform maximum power spectrum (MaxPS) show the linear relationship against torque experience by elbow joint to lift different load. As the conclusion, the best features is MaxPS because it has the lowest error than other features and

  4. Robust Features Of Surface Electromyography Signal

    Science.gov (United States)

    Sabri, M. I.; Miskon, M. F.; Yaacob, M. R.

    2013-12-01

    Nowadays, application of robotics in human life has been explored widely. Robotics exoskeleton system are one of drastically areas in recent robotic research that shows mimic impact in human life. These system have been developed significantly to be used for human power augmentation, robotics rehabilitation, human power assist, and haptic interaction in virtual reality. This paper focus on solving challenges in problem using neural signals and extracting human intent. Commonly, surface electromyography signal (sEMG) are used in order to control human intent for application exoskeleton robot. But the problem lies on difficulty of pattern recognition of the sEMG features due to high noises which are electrode and cable motion artifact, electrode noise, dermic noise, alternating current power line interface, and other noise came from electronic instrument. The main objective in this paper is to study the best features of electromyography in term of time domain (statistical analysis) and frequency domain (Fast Fourier Transform).The secondary objectives is to map the relationship between torque and best features of muscle unit activation potential (MaxPS and RMS) of biceps brachii. This project scope use primary data of 2 male sample subject which using same dominant hand (right handed), age between 20-27 years old, muscle diameter 32cm to 35cm and using single channel muscle (biceps brachii muscle). The experiment conduct 2 times repeated task of contraction and relaxation of biceps brachii when lifting different load from no load to 3kg with ascending 1kg The result shows that Fast Fourier Transform maximum power spectrum (MaxPS) has less error than mean value of reading compare to root mean square (RMS) value. Thus, Fast Fourier Transform maximum power spectrum (MaxPS) show the linear relationship against torque experience by elbow joint to lift different load. As the conclusion, the best features is MaxPS because it has the lowest error than other features and show

  5. Inter-day reliability of surface electromyography recordings of the lumbar part of erector spinae longissimus and trapezius descendens during box lifting.

    Science.gov (United States)

    Brandt, Mikkel; Andersen, Lars Louis; Samani, Afshin; Jakobsen, Markus Due; Madeleine, Pascal

    2017-12-11

    Low back pain and neck-shoulder pain are the most reported types of work-related musculoskeletal disorders, and performing heavy lifting at work and working with trunk rotation increase the risk of developing work-related musculoskeletal disorders. Surface electromyography (sEMG) provides information about the electrical activity of muscles. Thus it has the potential to retrieve indirect information about the physical exposure of specific muscles of workers during their actual work. This study aimed to investigate the inter-day reliability of absolute and normalized amplitude of sEMG measurements obtained during repeated standardized reference lifts. The inter-day reliability of sEMG of the erector spinae longissimus and trapezius descendens muscles was tested during standardized box lifts. The lifts were performed with loads of 3, 15 and 30 kg from floor to table and from table to table in three conditions, i.e., forearm length (short reaching distance), ¾ arm length (long reaching distance) and forearm length with trunk rotation. Absolute and normalized root mean square (absRMS and normRMS) values were extracted. In line with the guidelines for reporting reliability and agreement studies, we reported relative and absolute reliability estimated by intra class correlation (ICC 3,K ), standard error of measurement (SEM) and minimal detectable change in percent (MDC). The ICC 3,K was higher for absRMS compared with normRMS while SEM and maximal voluntary contraction (MVC) were similar. A total of 50 out of 56, i.e., 89%, and 41 out of 56, i.e., 73%, of the lifting situations were in the range from moderate to almost perfect for absRMS and normRMS, respectively. The SEM and MDC shoved more variation in the lifting situations performed from floor to table and in the trapezius descendens muscle than in the erector spinae longissimus muscle. This reliability study showed that maximum absRMS and normRMS were found to have a fair to substantial relative inter

  6. Assessment of work-related muscle strain by using surface EMG during test contractions interposed between work periods of simulateted mushroom picking

    DEFF Research Database (Denmark)

    Ohashi, Jun-Ya; Blangsted, Anne Katrine; Nielsen, Pernille Kofoed

    2010-01-01

    Surface electromyograms(EMG) during test contractions (TCs) were studied to assess the muscle strain in simulated mushroom picking. Additionally, the duration of the TC for the effective assessment was investigated. Nine female subjects performed standardized shoulder abduction and a stooped post...... during the TCs. AEMG and MPF fluctuated before W1 although the changes of RPE were small. Averaging several TCs was recommended to get stable results from TCs. EMG changes and appropriate TC conditions were discussed in relation to the adaptation in fatiguing contractions....

  7. A surface electromyography based objective method to identify patients with nonspecific chronic low back pain, presenting a flexion related movement control impairment.

    Science.gov (United States)

    Van Damme, Benedicte; Stevens, Veerle; Perneel, Christiaan; Van Tiggelen, Damien; Neyens, Ellen; Duvigneaud, Nathalie; Moerman, Luc; Danneels, Lieven

    2014-12-01

    Movement control impairments (MCI) are often present in patients with non-specific chronic low back pain (NS-CLBP). Therefore, movement control exercises are widely used to rehabilitate patients. However, the objective assessment remains difficult. The purpose of this study was to develop a statistical model, based on logistic regression analysis, to differentiate patients with NS-CLBP presenting a flexion-related MCI from healthy subjects. This model is based on trunk muscle activation patterns measured by surface electromyography (sEMG), during movement control exercises. Sixty-three healthy male subjects and 36 male patients with a flexion-related MCI participated in this study. Muscle activity of the internal obliques, the external obliques, the lumbar multifidus and the thoracic part of the iliocostalis was registered. Ratios of deep stabilizing to superficial torque producing muscle activity were calculated to examine trunk muscle recruitment patterns during 6 different exercises. Logistic regression analyses were performed (1) to define the ratios and exercises that were most discriminating between patients and non-patients, (2) to make a predictive model. K-Fold cross-validation was used to assess the performance of the predictive model. This study demonstrated that sEMG trunk muscle recruitment patterns during movement control tests, allows differentiating NSCLBP patients with a flexion-related MCI from healthy subjects. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Removing ECG Artifact from the Surface EMG Signal Using Adaptive Subtraction Technique

    Science.gov (United States)

    Abbaspour, S; Fallah, A

    2014-01-01

    Background: The electrocardiogram artifact is a major contamination in the electromyogram signals when electromyogram signal is recorded from upper trunk muscles and because of that the contaminated electromyogram is not useful. Objective: Removing electrocardiogram contamination from electromyogram signals. Methods: In this paper, the clean electromyogram signal, electrocardiogram artifact and electrocardiogram signal were recorded from leg muscles, the pectoralis major muscle of the left side and V4, respectively. After the pre-processing, contaminated electromyogram signal is simulated with a combination of clean electromyogram and electrocardiogram artifact. Then, contaminated electromyogram is cleaned using adaptive subtraction method. This method contains some steps; (1) QRS detection, (2) formation of electrocardiogram template by averaging the electrocardiogram complexes, (3) using low pass filter to remove undesirable artifacts, (4) subtraction. Results: Performance of our method is evaluated using qualitative criteria, power spectrum density and coherence and quantitative criteria signal to noise ratio, relative error and cross correlation. The result of signal to noise ratio, relative error and cross correlation is equal to 10.493, 0.04 and %97 respectively. Finally, there is a comparison between proposed method and some existing methods. Conclusion: The result indicates that adaptive subtraction method is somewhat effective to remove electrocardiogram artifact from contaminated electromyogram signal and has an acceptable result. PMID:25505766

  9. A Novel Phonology- and Radical-Coded Chinese Sign Language Recognition Framework Using Accelerometer and Surface Electromyography Sensors.

    Science.gov (United States)

    Cheng, Juan; Chen, Xun; Liu, Aiping; Peng, Hu

    2015-09-15

    Sign language recognition (SLR) is an important communication tool between the deaf and the external world. It is highly necessary to develop a worldwide continuous and large-vocabulary-scale SLR system for practical usage. In this paper, we propose a novel phonology- and radical-coded Chinese SLR framework to demonstrate the feasibility of continuous SLR using accelerometer (ACC) and surface electromyography (sEMG) sensors. The continuous Chinese characters, consisting of coded sign gestures, are first segmented into active segments using EMG signals by means of moving average algorithm. Then, features of each component are extracted from both ACC and sEMG signals of active segments (i.e., palm orientation represented by the mean and variance of ACC signals, hand movement represented by the fixed-point ACC sequence, and hand shape represented by both the mean absolute value (MAV) and autoregressive model coefficients (ARs)). Afterwards, palm orientation is first classified, distinguishing "Palm Downward" sign gestures from "Palm Inward" ones. Only the "Palm Inward" gestures are sent for further hand movement and hand shape recognition by dynamic time warping (DTW) algorithm and hidden Markov models (HMM) respectively. Finally, component recognition results are integrated to identify one certain coded gesture. Experimental results demonstrate that the proposed SLR framework with a vocabulary scale of 223 characters can achieve an averaged recognition accuracy of 96.01% ± 0.83% for coded gesture recognition tasks and 92.73% ± 1.47% for character recognition tasks. Besides, it demonstrats that sEMG signals are rather consistent for a given hand shape independent of hand movements. Hence, the number of training samples will not be significantly increased when the vocabulary scale increases, since not only the number of the completely new proposed coded gestures is constant and limited, but also the transition movement which connects successive signs needs no

  10. Influence on grip of knife handle surface characteristics and wearing protective gloves.

    Science.gov (United States)

    Claudon, Laurent

    2006-11-01

    Ten subjects were asked to apply maximum torques on knife handles with either their bare hand or their hand wearing a Kevlar fibre protective glove. Four knife handles (2 roughnesses, 2 hardnesses) were tested. Surface electromyograms of 6 upper limb and shoulder muscles were recorded and subject opinions on both knife handle hardness and friction in the hand were also assessed. The results revealed the significant influence of wearing gloves (pgloves greatly increased the torque independently of the other two parameters. Under the bare hand condition, a 90 degrees ShA slightly rough handle provided the greatest torque. Subject opinion agreed with the observed effects on recorded torque values except for the hardness factor, for which a preference for the 70 degrees ShA value over the 90 degrees ShA value emerged.

  11. Analysis of High-Density Surface EMG and Finger Pressure in the Left Forearm of Violin Players: A Feasibility Study.

    Science.gov (United States)

    Cattarello, Paolo; Merletti, Roberto; Petracca, Francesco

    2017-09-01

    Wrist and finger flexor muscles of the left hand were evaluated using high-density surface EMG (HDsEMG) in 17 violin players. Pressure sensors also were mounted below the second string of the violin to evaluate, simultaneously, finger pressure. Electrode grid size was 110x70 mm (12x8 electrodes with interelectrode distance=10 mm and Ø=3 mm). The study objective was to observe the activation patterns of these muscles while the violinists sequentially played four notes--SI (B), DO# (C#), RE (D), MI (E)--at 2 bows/s (one bow up in 0.5 s and one down in 0.5 s) and 4 bows/s on the second string, while producing a constant (CONST) or ramp (RAMP) sound volume. HDsEMG images obtained while playing the notes were compared with those obtained during isometric radial or ulnar flexion of the wrist or fingers. Two image descriptors provided information on image differences. Results showed that the technique was reliable and provided reliable signals, and that recognizably different sEMG images could be associated with the four notes tested, despite the variability within and between subjects playing the same note. sEMG activity of the left hand muscles and pressure on the string in the RAMP task were strongly affected in some individuals by the sound volume (controlled by the right hand) and much less in other individuals. These findings question whether there is an individual or generally optimal way of pressing violin strings with the left hand. The answer to this question might substantially modify the teaching of string instruments.

  12. A modified algorithm of the combined ensemble empirical mode decomposition and independent component analysis for the removal of cardiac artifacts from neuromuscular electrical signals

    International Nuclear Information System (INIS)

    Lee, Kwang Jin; Lee, Boreom; Choi, Eue Keun; Oh, Seil; Lee, Seung Min

    2014-01-01

    Neuronal and muscular electrical signals contain useful information about the neuromuscular system, with which researchers have been investigating the relationship of various neurological disorders and the neuromuscular system. However, neuromuscular signals can be critically contaminated by cardiac electrical activity (CEA) such as the electrocardiogram (ECG) which confounds data analysis. The purpose of our study is to provide a method for removing cardiac electrical artifacts from the neuromuscular signals recorded. We propose a new method for cardiac artifact removal which modifies the algorithm combining ensemble empirical mode decomposition (EEMD) and independent component analysis (ICA). We compare our approach with a cubic smoothing spline method and the previous combined EEMD and ICA for various signal-to-noise ratio measures in simulated noisy physiological signals using a surface electromyogram (sEMG). Finally, we apply the proposed method to two real-life sets of data such as sEMG with ECG artifacts and ambulatory dog cardiac autonomic nervous signals measured from the ganglia near the heart, which are also contaminated with CEA. Our method can not only extract and remove artifacts, but can also preserve the spectral content of the neuromuscular signals. (paper)

  13. Selection of suitable hand gestures for reliable myoelectric human computer interface.

    Science.gov (United States)

    Castro, Maria Claudia F; Arjunan, Sridhar P; Kumar, Dinesh K

    2015-04-09

    Myoelectric controlled prosthetic hand requires machine based identification of hand gestures using surface electromyogram (sEMG) recorded from the forearm muscles. This study has observed that a sub-set of the hand gestures have to be selected for an accurate automated hand gesture recognition, and reports a method to select these gestures to maximize the sensitivity and specificity. Experiments were conducted where sEMG was recorded from the muscles of the forearm while subjects performed hand gestures and then was classified off-line. The performances of ten gestures were ranked using the proposed Positive-Negative Performance Measurement Index (PNM), generated by a series of confusion matrices. When using all the ten gestures, the sensitivity and specificity was 80.0% and 97.8%. After ranking the gestures using the PNM, six gestures were selected and these gave sensitivity and specificity greater than 95% (96.5% and 99.3%); Hand open, Hand close, Little finger flexion, Ring finger flexion, Middle finger flexion and Thumb flexion. This work has shown that reliable myoelectric based human computer interface systems require careful selection of the gestures that have to be recognized and without such selection, the reliability is poor.

  14. Comparison of muscles activity of abled bodied and amputee subjects for around shoulder movement.

    Science.gov (United States)

    Kaur, Amanpreet; Agarwal, Ravinder; Kumar, Amod

    2016-05-12

    Worldwide, about 56% of the amputees are upper limb amputees. This research deals a method with two-channel surface electromyogram (SEMG) signal recorded from around shoulder to estimate the changes in muscle activity in non-amputee and the residual limb of trans humeral amputees with different movements of arm. Identification of different muscles activity of near shoulder amputee and non-amputee persons. SEMG signal were acquired during three distinct exercises from three-selected muscles location around shoulder. The participants were asked to move their dominant arm from an assigned position to record their muscles activity recorded with change in position. Results shows the muscles activity in scalene is more than the other muscles like pectoralis and infraspinatus with the same shoulder motion. In addition, STFT (Short-Time Fourier Transform) spectrogram with window length of 256 samples at maximum of 512 frequency bins using hamming window has used to identify the signal for the maximum muscles activity with best resolution in spectrum plot. The results suggest that one can use this analysis for making a suitable device for around shoulder prosthetic users based on muscles activation of amputee persons.

  15. Transvaginal electrical stimulation with surface-EMG biofeedback in managing stress urinary incontinence in women of premenopausal age: a double-blind, placebo-controlled, randomized clinical trial.

    Science.gov (United States)

    Terlikowski, Robert; Dobrzycka, Bozena; Kinalski, Maciej; Kuryliszyn-Moskal, Anna; Terlikowski, Slawomir J

    2013-10-01

    The aim of this study was to evaluate the results of conservative treatment of urodynamic stress urinary incontinence (SUI) using transvaginal electrical stimulation with surface-electromyography-assisted biofeedback (TVES + sEMG) in women of premenopausal age. One hundred and two patients with SUI were divided into two groups: active (n = 68) and placebo (n = 34) TVES + sEMG. The treatment lasted for 8 weeks and consisted of two sessions per day. Women were evaluated before and after the intervention by pad test, voiding diary, urodynamic test, and the Incontinence Quality of Life Questionnaire (I-QOL). Mean urinary leakage on a standard pad test at the end of 8th week was significantly lower in the active than the placebo group (19.5 ± 13.6 vs. 39.8 ± 28.5). Mean urinary leakage on a 24-h pad test was significantly reduced in the active group at the end of 8th and 16th weeks compared with the placebo group (8.2 ± 14.8 vs. 14.6 ± 18.9 and 6.1 ± 11.4 vs. 18.2 ± 20.8, respectively). There was also a significant improvement in muscle strength as measured by the Oxford scale in the active vs the placebo group after 8 and 16 weeks (4.2 vs 2.6 and 4.1 vs 2.7, respectively). No significant difference was found between groups in urodynamic data before and after treatment. At the end of 8th week, the mean I-QOL score in the active vs the placebo group was 78.2 ± 17.9 vs 55.9 ± 14.2, respectively, and at the end of 16th week 80.8 ± 24.1 vs. 50.6 ± 14.9, respectively. Our study showed that TVES + sEMG is a trustworthy method of treatment in premenopausal women with SUI; however, its reliability needs to be established.

  16. New Swallowing Evaluation Using Piezoelectricity in Normal Individuals.

    Science.gov (United States)

    Sogawa, Yuichiro; Kimura, Shinji; Harigai, Toru; Sakurai, Naoki; Toyosato, Akira; Nishikawa, Taro; Inoue, Makoto; Murasawa, Akira; Endo, Naoto

    2015-12-01

    This study aimed to elucidate the relationship between the piezoelectric waveform latency, hyoid bone movement, surface electromyogram (sEMG), and the pharyngeal transit time (PTT) during swallowing. Forty-one healthy subjects were divided into three age groups: younger (20-39 years, n = 8), middle-aged (40-59 years, n = 9), and older (60-79 years, n = 24). Motion analysis of the hyoid bone using videofluorography (VF), waveform analysis of the front neck using piezoelectric films, and sEMG of the suprahyoid muscle group were performed simultaneously. Latencies of the three movement phases were defined as upward (VFS1), forward (VFS2), and returning to starting position (VFS3). The three phases of the piezoelectric waveform-from wave initiation of the negative wave to the start of the second deep negative wave; from the start of the second deep negative wave to the start of the last positive wave (SLPW); and from the SLPW to the end of the last positive wave-were defined as PS1, PS2, and PS3, respectively. VFS1-3 and PS1-3 were significantly correlated. VFS1 and PS1 latencies were significantly longer with thick liquid than with thin liquid. VFS2, PS1, and PS2 latencies were longer in the older group than in the other two groups. The start of PS1 was nearly equal to those of sEMG and VFS1. Bolus arrival time in the valleculae was statistically equal to the end of the PS1 with both thin and thick liquids. To establish the swallowing screening using Piezoelectric film, further investigation is necessary in the dysphagia patients.

  17. A Variance Distribution Model of Surface EMG Signals Based on Inverse Gamma Distribution.

    Science.gov (United States)

    Hayashi, Hideaki; Furui, Akira; Kurita, Yuichi; Tsuji, Toshio

    2017-11-01

    Objective: This paper describes the formulation of a surface electromyogram (EMG) model capable of representing the variance distribution of EMG signals. Methods: In the model, EMG signals are handled based on a Gaussian white noise process with a mean of zero for each variance value. EMG signal variance is taken as a random variable that follows inverse gamma distribution, allowing the representation of noise superimposed onto this variance. Variance distribution estimation based on marginal likelihood maximization is also outlined in this paper. The procedure can be approximated using rectified and smoothed EMG signals, thereby allowing the determination of distribution parameters in real time at low computational cost. Results: A simulation experiment was performed to evaluate the accuracy of distribution estimation using artificially generated EMG signals, with results demonstrating that the proposed model's accuracy is higher than that of maximum-likelihood-based estimation. Analysis of variance distribution using real EMG data also suggested a relationship between variance distribution and signal-dependent noise. Conclusion: The study reported here was conducted to examine the performance of a proposed surface EMG model capable of representing variance distribution and a related distribution parameter estimation method. Experiments using artificial and real EMG data demonstrated the validity of the model. Significance: Variance distribution estimated using the proposed model exhibits potential in the estimation of muscle force. Objective: This paper describes the formulation of a surface electromyogram (EMG) model capable of representing the variance distribution of EMG signals. Methods: In the model, EMG signals are handled based on a Gaussian white noise process with a mean of zero for each variance value. EMG signal variance is taken as a random variable that follows inverse gamma distribution, allowing the representation of noise superimposed onto this

  18. Assessment of work-related muscle strain by using surface EMG during test contractions interposed between work periods of simulateted mushroom picking

    DEFF Research Database (Denmark)

    Ohashi, Jun-Ya; Blangsted, Anne Katrine; Nielsen, Pernille Kofoed

    2010-01-01

    Surface electromyograms(EMG) during test contractions (TCs) were studied to assess the muscle strain in simulated mushroom picking. Additionally, the duration of the TC for the effective assessment was investigated. Nine female subjects performed standardized shoulder abduction and a stooped...... minutes in the rest periods. EMGs were recorded from the trapezius, infraspinatus, deltoid, and erector spinae muscles. The amplitude of EMG (AEMG) and mean power frequency (MPF) of EMG were calculated. Each TC was divided equally into three parts. Ratings of perceived exertion (RPE) in the neck, shoulder...... during the TCs. AEMG and MPF fluctuated before W1 although the changes of RPE were small. Averaging several TCs was recommended to get stable results from TCs. EMG changes and appropriate TC conditions were discussed in relation to the adaptation in fatiguing contractions....

  19. A Novel Feature Optimization for Wearable Human-Computer Interfaces Using Surface Electromyography Sensors

    Directory of Open Access Journals (Sweden)

    Han Sun

    2018-03-01

    Full Text Available The novel human-computer interface (HCI using bioelectrical signals as input is a valuable tool to improve the lives of people with disabilities. In this paper, surface electromyography (sEMG signals induced by four classes of wrist movements were acquired from four sites on the lower arm with our designed system. Forty-two features were extracted from the time, frequency and time-frequency domains. Optimal channels were determined from single-channel classification performance rank. The optimal-feature selection was according to a modified entropy criteria (EC and Fisher discrimination (FD criteria. The feature selection results were evaluated by four different classifiers, and compared with other conventional feature subsets. In online tests, the wearable system acquired real-time sEMG signals. The selected features and trained classifier model were used to control a telecar through four different paradigms in a designed environment with simple obstacles. Performance was evaluated based on travel time (TT and recognition rate (RR. The results of hardware evaluation verified the feasibility of our acquisition systems, and ensured signal quality. Single-channel analysis results indicated that the channel located on the extensor carpi ulnaris (ECU performed best with mean classification accuracy of 97.45% for all movement’s pairs. Channels placed on ECU and the extensor carpi radialis (ECR were selected according to the accuracy rank. Experimental results showed that the proposed FD method was better than other feature selection methods and single-type features. The combination of FD and random forest (RF performed best in offline analysis, with 96.77% multi-class RR. Online results illustrated that the state-machine paradigm with a 125 ms window had the highest maneuverability and was closest to real-life control. Subjects could accomplish online sessions by three sEMG-based paradigms, with average times of 46.02, 49.06 and 48.08 s

  20. Relationship between lower limb position and pelvic floor muscle surface electromyography activity in menopausal women: a prospective observational study

    Directory of Open Access Journals (Sweden)

    Halski T

    2017-01-01

    Full Text Available Tomasz Halski,1 Kuba Ptaszkowski,2 Lucyna Słupska,1 Robert Dymarek,3 Małgorzata Paprocka-Borowicz2 1Department of Physiotherapy, Opole Medical School, Opole, 2Department of Clinical Biomechanics and Physiotherapy in Motor System Disorders, 3Department of Nervous System Diseases, Faculty of Health Science, Wroclaw Medical University, Wroclaw, Poland Objectives: In physiotherapeutic practice, special attention is being given to the reciprocal anatomical, physiological, and biomechanical relationship of the pelvis and the structures connected to it. However, the scientific literature shows mainly the theoretical information about their mutual connections. The lack of information about these relations from a practical aspect coupled with the paucity of scientific papers on the impact of posture changes on the pelvic floor led the authors to conduct this study. The primary aim of this study was to compare the resting and functional bioelectrical activities of pelvic floor muscles (PFMs depending on three different positions of the lower limbs (positions A, B, and C in the supine position.Materials and methods: This was a prospective observational study evaluating resting and functional activities of the PFM depending on the position of the lower limbs. The study was carried out at the Department and Clinic of Urology, University Hospital in Wroclaw, Poland and the target group were women in the menopausal period. Bioelectrical activity of PFM was recorded using a surface electromyographic instrument in the supine position. Results of the values obtained in A, B, and C positions were compared using a one-way analysis of variance.Results: In position A, the average resting surface electromyography (sEMG activity of PFM was 6.9±2.6 µV; in position B, the result was 6.9±2.5 µV and in position C, the resting sEMG activity was 5.7±1.8 µV (P=0.0102. The results of the functional bioelectrical activity of PFM were as follows: position A – 20.3

  1. Electromyogram-based neural network control of transhumeral prostheses.

    Science.gov (United States)

    Pulliam, Christopher L; Lambrecht, Joris M; Kirsch, Robert F

    2011-01-01

    Upper-limb amputation can cause a great deal of functional impairment for patients, particularly for those with amputation at or above the elbow. Our long-term objective is to improve functional outcomes for patients with amputation by integrating a fully implanted electromyographic (EMG) recording system with a wireless telemetry system that communicates with the patient's prosthesis. We believe that this should generate a scheme that will allow patients to robustly control multiple degrees of freedom simultaneously. The goal of this study is to evaluate the feasibility of predicting dynamic arm movements (both flexion/extension and pronation/supination) based on EMG signals from a set of muscles that would likely be intact in patients with transhumeral amputation. We recorded movement kinematics and EMG signals from seven muscles during a variety of movements with different complexities. Time-delayed artificial neural networks were then trained offline to predict the measured arm trajectories based on features extracted from the measured EMG signals. We evaluated the relative effectiveness of various muscle subsets. Predicted movement trajectories had average root-mean-square errors of approximately 15.7° and 24.9° and average R(2) values of approximately 0.81 and 0.46 for elbow flexion/extension and forearm pronation/supination, respectively.

  2. Seizure Onset Detection based on one sEMG channel

    DEFF Research Database (Denmark)

    Conradsen, Isa; Beniczky, Sandor; Hoppe, Karsten

    2011-01-01

    with a Butterworth filter with a cut-off frequency of 150 Hz. The number of zero-crossings with a hysteresis of ±50μV is the only feature extracted. The number of counts in a window of 1 second and the number of windows to make a detection is tested with a leave-one-out method. On 6 patients the method performs...... with a sensitivity of 100%, a median latency of 7.6 seconds and a median false detection rate of 0.04/h....

  3. Central motor control failure in fibromyalgia: a surface electromyography study.

    Science.gov (United States)

    Casale, Roberto; Sarzi-Puttini, Piercarlo; Atzeni, Fabiola; Gazzoni, Marco; Buskila, Dan; Rainoldi, Alberto

    2009-07-01

    Fibromyalgia (FM) is characterised by diffuse musculoskeletal pain and stiffness at multiple sites, tender points in characteristic locations, and the frequent presence of symptoms such as fatigue. The aim of this study was to assess whether the myoelectrical manifestations of fatigue in patients affected by FM are central or peripheral in origin. Eight female patients aged 55.6 +/- 13.6 years (FM group) and eight healthy female volunteers aged 50.3 +/- 9.3 years (MCG) were studied by means of non-invasive surface electromyography (s-EMG) involving a linear array of 16 electrodes placed on the skin overlying the biceps brachii muscle, with muscle fatigue being evoked by means of voluntary and involuntary (electrically elicited) contractions. Maximal voluntary contractions (MVCs), motor unit action potential conduction velocity distributions (mean +/- SD and skewness), and the mean power frequency of the spectrum (MNF) were estimated in order to assess whether there were any significant differences between the two groups and contraction types. The motor pattern of recruitment during voluntary contractions was altered in the FM patients, who also showed fewer myoelectrical manifestations of fatigue (normalised conduction velocity rate of changes: -0.074 +/- 0.052%/s in FM vs -0.196 +/- 0.133%/s in MCG; normalised MNF rate of changes: -0.29 +/- 0.16%/s in FM vs -0.66 +/- 0.34%/s in MCG). Mean conduction velocity distribution and skewnesses values were higher (p fatigue in FM is the electrophysiological expression of muscle remodelling in terms of the prevalence of slow conducting fatigue-resistant type I fibres. As the only between-group differences concerned voluntary contractions, they are probably more related to central motor control failure than muscle membrane alterations, which suggests pathological muscle fibre remodelling related to altered suprasegmental control.

  4. Central motor control failure in fibromyalgia: a surface electromyography study

    Science.gov (United States)

    Casale, Roberto; Sarzi-Puttini, Piercarlo; Atzeni, Fabiola; Gazzoni, Marco; Buskila, Dan; Rainoldi, Alberto

    2009-01-01

    Background Fibromyalgia (FM) is characterised by diffuse musculoskeletal pain and stiffness at multiple sites, tender points in characteristic locations, and the frequent presence of symptoms such as fatigue. The aim of this study was to assess whether the myoelectrical manifestations of fatigue in patients affected by FM are central or peripheral in origin. Methods Eight female patients aged 55.6 ± 13.6 years (FM group) and eight healthy female volunteers aged 50.3 ± 9.3 years (MCG) were studied by means of non-invasive surface electromyography (s-EMG) involving a linear array of 16 electrodes placed on the skin overlying the biceps brachii muscle, with muscle fatigue being evoked by means of voluntary and involuntary (electrically elicited) contractions. Maximal voluntary contractions (MVCs), motor unit action potential conduction velocity distributions (mean ± SD and skewness), and the mean power frequency of the spectrum (MNF) were estimated in order to assess whether there were any significant differences between the two groups and contraction types. Results The motor pattern of recruitment during voluntary contractions was altered in the FM patients, who also showed fewer myoelectrical manifestations of fatigue (normalised conduction velocity rate of changes: -0.074 ± 0.052%/s in FM vs -0.196 ± 0.133%/s in MCG; normalised MNF rate of changes: -0.29 ± 0.16%/s in FM vs -0.66 ± 0.34%/s in MCG). Mean conduction velocity distribution and skewnesses values were higher (p fatigue in FM is the electrophysiological expression of muscle remodelling in terms of the prevalence of slow conducting fatigue-resistant type I fibres. As the only between-group differences concerned voluntary contractions, they are probably more related to central motor control failure than muscle membrane alterations, which suggests pathological muscle fibre remodelling related to altered suprasegmental control. PMID:19570214

  5. Central motor control failure in fibromyalgia: a surface electromyography study

    Directory of Open Access Journals (Sweden)

    Buskila Dan

    2009-07-01

    Full Text Available Abstract Background Fibromyalgia (FM is characterised by diffuse musculoskeletal pain and stiffness at multiple sites, tender points in characteristic locations, and the frequent presence of symptoms such as fatigue. The aim of this study was to assess whether the myoelectrical manifestations of fatigue in patients affected by FM are central or peripheral in origin. Methods Eight female patients aged 55.6 ± 13.6 years (FM group and eight healthy female volunteers aged 50.3 ± 9.3 years (MCG were studied by means of non-invasive surface electromyography (s-EMG involving a linear array of 16 electrodes placed on the skin overlying the biceps brachii muscle, with muscle fatigue being evoked by means of voluntary and involuntary (electrically elicited contractions. Maximal voluntary contractions (MVCs, motor unit action potential conduction velocity distributions (mean ± SD and skewness, and the mean power frequency of the spectrum (MNF were estimated in order to assess whether there were any significant differences between the two groups and contraction types. Results The motor pattern of recruitment during voluntary contractions was altered in the FM patients, who also showed fewer myoelectrical manifestations of fatigue (normalised conduction velocity rate of changes: -0.074 ± 0.052%/s in FM vs -0.196 ± 0.133%/s in MCG; normalised MNF rate of changes: -0.29 ± 0.16%/s in FM vs -0.66 ± 0.34%/s in MCG. Mean conduction velocity distribution and skewnesses values were higher (p Conclusion The apparent paradox of fewer myoelectrical manifestations of fatigue in FM is the electrophysiological expression of muscle remodelling in terms of the prevalence of slow conducting fatigue-resistant type I fibres. As the only between-group differences concerned voluntary contractions, they are probably more related to central motor control failure than muscle membrane alterations, which suggests pathological muscle fibre remodelling related to altered

  6. Reliability of a combined biomechanical and surface electromyographical analysis system during dynamic barbell squat exercise.

    Science.gov (United States)

    Brandon, Raphael; Howatson, Glyn; Hunter, Angus

    2011-10-01

    An analysis system for barbell weightlifting exercises is proposed to record reliable performance and neuromuscular responses. The system consists of surface electromyography (sEMG) synchronized with electrogoniometry and a barbell position transducer. The purpose of this study was to establish the reliability of the three components of the system. Nine males (age 28.9 ± 4.8 years, mass 85.7 ± 15.1 kg) performed squat exercise at three loads on three separate trial days. A data acquisition and software system processed maximal knee angle (flexion), mean power for the concentric phase of squat exercise, and normalized root mean square of the vastus lateralis. Inter-trial coefficients of variation for each variable were calculated as 5.3%, 7.8%, and 7.5% respectively. In addition, knee joint motion and barbell displacement were significantly related to each other (bar displacement (m) = 1.39-0.0057 × knee angle (degress), with goodness-of-fit value, r² = 0.817), suggesting knee goniometry alone can represent the kinematics of a multi-joint squat exercise. The proven reliability of the three components of this system allows for real-time monitoring of resistance exercise using the preferred training methods of athletes, which could be valuable in the understanding of the neuromuscular response of elite strength training methods.

  7. Identification of Onset Of Fatigue in Biceps Brachii Muscles Using Surface EMG and Multifractal DMA Alogrithm.

    Science.gov (United States)

    Marri, Kiran; Swaminathan, Ramakrishnan

    2015-01-01

    Prolonged and repeated fatigue conditions can cause muscle damage and adversely impact coordination in dynamic contractions. Hence it is important to determine the onset of muscle fatigue (OMF) in clinical rehabilitation and sports medicine. The aim of this study is to propose a method for analyzing surface electromyography (sEMG) signals and identify OMF using multifractal detrending moving average algorithm (MFDMA). Signals are recorded from biceps brachii muscles of twenty two healthy volunteers while performing standard curl exercise. The first instance of muscle discomfort during curl exercise is considered as experimental OMF. Signals are pre-processed and divided into 1-second epoch for MFDMA analysis. Degree of multifractality (DOM) feature is calculated from multifractal spectrum. Further, the variance of DOM is computed and OMF is calculated from instances of high peaks. The analysis is carried out by dividing the entire duration into six equal zones for time axis normalization. High peaks are observed in zones where subjects reported muscle discomfort. First muscle discomfort occurred in third and forth zones for majority of subjects. The calculated and experimental muscle discomfort zone closely matched in 72% of subjects indicating that multifractal technique may be a good method for detecting onset of fatigue. The experimental data may have an element of subjectivity in identifying muscle discomfort. This work can also be useful to analyze progressive changes in muscle dynamics in neuromuscular condition and co-contraction activity.

  8. The surface electromyographic evaluation of the Functional Reach in elderly subjects.

    Science.gov (United States)

    Maranesi, E; Fioretti, S; Ghetti, G G; Rabini, R A; Burattini, L; Mercante, O; Di Nardo, F

    2016-02-01

    This study proposes a comprehensive assessment of myoelectric activity of the main muscles involved in the Functional Reach (FR) test, in 24 elderly subjects. A specific protocol for the surface electromyography (sEMG) signal acquisition during FR-test was developed. Results show that anterior muscles activate following a caudo-cranial order. Tibialis Anterior (TA) is the first to be activated (-18.0±16.3% of the FR-period), together with Rectus Femoris (-10.4±17.9%). Then, Rectus Abdominis (19.7±24.7%) and Sternocleidomastoideus (19.9±15.6%) activate after the FR-start. Hamstrings, Soleus, and L4-level Erectores Spinae (posterior muscles) activate after the FR-start in this order (11.4±16.8%, 17.7±16.6%, and 35.2±29.0%, respectively) and remain active until the movement end. The analysis of the kinematic strategies adopted by subjects revealed an association between TA-activation patterns and two kinematic strategies (hip/mixed strategy), quantified by an increase (pelderly subjects, providing an early contribution in building a reference frame for balance assessment in clinical context. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Spatial distribution of surface EMG on trapezius and lumbar muscles of violin and cello players in single note playing.

    Science.gov (United States)

    Afsharipour, Babak; Petracca, Francesco; Gasparini, Mauro; Merletti, Roberto

    2016-12-01

    Musicians activate their muscles in different patterns, depending on their posture, the instrument being played, and their experience level. Bipolar surface electrodes have been used in the past to monitor such activity, but this method is highly sensitive to the location of the electrode pair. In this work, the spatial distribution of surface EMG (sEMG) of the right trapezius and right and left erector spinae muscles were studied in 16 violin players and 11 cello players. Musicians played their instrument one string at a time in sitting position with/without backrest support. A 64 sEMG electrode (16×4) grid, 10mm inter-electrode distance (IED), was placed over the middle and lower trapezius (MT and LT) of the bowing arm. Two 16×2 electrode grids (IED=10mm) were placed on the left and right erector spinae muscles. Subjects played each of the four strings of the instrument either in large (1bow/s) or detaché tip/tail (8bows/s) bowing in two sessions (two days). In each of two days, measurements were repeated after half an hour of exercise to see the effect of exercise on the muscle activity and signal stability. A "muscle activity index" (MAI) was defined as the spatial average of the segmented active region of the RMS map. Spatial maps were automatically segmented using the watershed algorithm and thresholding. Results showed that, for violin players, sliding the bow upward from the tip toward the tail results in a higher MAI for the trapezius muscle than a downward bow. On the contrary, in cello players, higher MAI is produced in the tail to tip movement. For both instruments, an increasing MAI in the trapezius was observed as the string position became increasingly lateral, from string 1 (most medial) toward string 4 (most lateral). Half an hour of performance did not cause significant differences between the signal quality and the MAI values measured before and after the exercise. The MAI of the left and right erector spinae was smaller in the case of

  10. Relationship between lower limb position and pelvic floor muscle surface electromyography activity in menopausal women: a prospective observational study

    Science.gov (United States)

    Halski, Tomasz; Ptaszkowski, Kuba; Słupska, Lucyna; Dymarek, Robert; Paprocka-Borowicz, Małgorzata

    2017-01-01

    Objectives In physiotherapeutic practice, special attention is being given to the reciprocal anatomical, physiological, and biomechanical relationship of the pelvis and the structures connected to it. However, the scientific literature shows mainly the theoretical information about their mutual connections. The lack of information about these relations from a practical aspect coupled with the paucity of scientific papers on the impact of posture changes on the pelvic floor led the authors to conduct this study. The primary aim of this study was to compare the resting and functional bioelectrical activities of pelvic floor muscles (PFMs) depending on three different positions of the lower limbs (positions A, B, and C) in the supine position. Materials and methods This was a prospective observational study evaluating resting and functional activities of the PFM depending on the position of the lower limbs. The study was carried out at the Department and Clinic of Urology, University Hospital in Wroclaw, Poland and the target group were women in the menopausal period. Bioelectrical activity of PFM was recorded using a surface electromyographic instrument in the supine position. Results of the values obtained in A, B, and C positions were compared using a one-way analysis of variance. Results In position A, the average resting surface electromyography (sEMG) activity of PFM was 6.9±2.6 µV; in position B, the result was 6.9±2.5 µV and in position C, the resting sEMG activity was 5.7±1.8 µV (P=0.0102). The results of the functional bioelectrical activity of PFM were as follows: position A – 20.3±11.8 µV, position B – 19.9±10.6 µV, and position C – 25.3±10.9 µV (P=0.0104). Conclusion The results showed that in the supine position, the PFM achieved the lowest resting activity and the highest functional activity. Therefore, the supine position can be recommended for the diagnosis and therapy of weakened PFM. PMID:28115836

  11. Minimal surfaces

    CERN Document Server

    Dierkes, Ulrich; Sauvigny, Friedrich; Jakob, Ruben; Kuster, Albrecht

    2010-01-01

    Minimal Surfaces is the first volume of a three volume treatise on minimal surfaces (Grundlehren Nr. 339-341). Each volume can be read and studied independently of the others. The central theme is boundary value problems for minimal surfaces. The treatise is a substantially revised and extended version of the monograph Minimal Surfaces I, II (Grundlehren Nr. 295 & 296). The first volume begins with an exposition of basic ideas of the theory of surfaces in three-dimensional Euclidean space, followed by an introduction of minimal surfaces as stationary points of area, or equivalently

  12. Surface EMG decomposition based on K-means clustering and convolution kernel compensation.

    Science.gov (United States)

    Ning, Yong; Zhu, Xiangjun; Zhu, Shanan; Zhang, Yingchun

    2015-03-01

    A new approach has been developed by combining the K-mean clustering (KMC) method and a modified convolution kernel compensation (CKC) method for multichannel surface electromyogram (EMG) decomposition. The KMC method was first utilized to cluster vectors of observations at different time instants and then estimate the initial innervation pulse train (IPT). The CKC method, modified with a novel multistep iterative process, was conducted to update the estimated IPT. The performance of the proposed K-means clustering-Modified CKC (KmCKC) approach was evaluated by reconstructing IPTs from both simulated and experimental surface EMG signals. The KmCKC approach successfully reconstructed all 10 IPTs from the simulated surface EMG signals with true positive rates (TPR) of over 90% with a low signal-to-noise ratio (SNR) of -10 dB. More than 10 motor units were also successfully extracted from the 64-channel experimental surface EMG signals of the first dorsal interosseous (FDI) muscles when a contraction force was held at 8 N by using the KmCKC approach. A "two-source" test was further conducted with 64-channel surface EMG signals. The high percentage of common MUs and common pulses (over 92% at all force levels) between the IPTs reconstructed from the two independent groups of surface EMG signals demonstrates the reliability and capability of the proposed KmCKC approach in multichannel surface EMG decomposition. Results from both simulated and experimental data are consistent and confirm that the proposed KmCKC approach can successfully reconstruct IPTs with high accuracy at different levels of contraction.

  13. Comparison of surface and intramuscular EMG pattern recognition for simultaneous wrist/hand motion classification.

    Science.gov (United States)

    Smith, Lauren H; Hargrove, Levi J

    2013-01-01

    The simultaneous control of multiple degrees of freedom (DOFs) is important for the intuitive, life-like control of artificial limbs. The objective of this study was to determine whether the use of intramuscular electromyogram (EMG) improved pattern classification of simultaneous wrist/hand movements compared to surface EMG. Two pattern classification methods were used in this analysis, and were trained to predict 1-DOF and 2-DOF movements involving wrist rotation, wrist flexion/extension, and hand open/close. The classification methods used were (1) a single pattern classifier discriminating between 1-DOF and 2-DOF motion classes, and (2) a parallel set of three classifiers to predict the activity of each of the 3 DOFs. We demonstrate that in this combined wrist/hand classification task, the use of intramuscular EMG significantly decreases classification error compared to surface EMG for the parallel configuration (p<0.01), but not for the single classifier. We also show that the use of intramuscular EMG mitigates the increase in errors produced when the parallel classifier method is trained without 2-DOF motion class data.

  14. Rumble surfaces

    CSIR Research Space (South Africa)

    National Institute for Transport and Road

    1977-01-01

    Full Text Available Rumble surfaces are intermittent short lengths of coarse-textured road surfacings on which vehicle tyres produce a rumbling sound. used in conjunction with appropriate roadsigns and markings, they can reduce accidents on rural roads by alerting...

  15. Surface thermodynamics

    International Nuclear Information System (INIS)

    Garcia-Moliner, F.

    1975-01-01

    Basic thermodynamics of a system consisting of two bulk phases with an interface. Solid surfaces: general. Discussion of experimental data on surface tension and related concepts. Adsorption thermodynamics in the Gibbsian scheme. Adsorption on inert solid adsorbents. Systems with electrical charges: chemistry and thermodynamics of imperfect crystals. Thermodynamics of charged surfaces. Simple models of charge transfer chemisorption. Adsorption heat and related concepts. Surface phase transitions

  16. Superhydrophobic surfaces

    Science.gov (United States)

    Wang, Evelyn N; McCarthy, Matthew; Enright, Ryan; Culver, James N; Gerasopoulos, Konstantinos; Ghodssi, Reza

    2015-03-24

    Surfaces having a hierarchical structure--having features of both microscale and nanoscale dimensions--can exhibit superhydrophobic properties and advantageous condensation and heat transfer properties. The hierarchical surfaces can be fabricated using biological nanostructures, such as viruses as a self-assembled nanoscale template.

  17. Spherical Surfaces

    DEFF Research Database (Denmark)

    Brander, David

    2016-01-01

    We study surfaces of constant positive Gauss curvature in Euclidean 3-space via the harmonicity of the Gauss map. Using the loop group representation, we solve the regular and the singular geometric Cauchy problems for these surfaces, and use these solutions to compute several new examples. We give...

  18. Modeling of surface myoelectric signals--Part II: Model-based signal interpretation.

    Science.gov (United States)

    Merletti, R; Roy, S H; Kupa, E; Roatta, S; Granata, A

    1999-07-01

    Experimental electromyogram (EMG) data from the human biceps brachii were simulated using the model described in [10] of this work. A multichannel linear electrode array, spanning the length of the biceps, was used to detect monopolar and bipolar signals, from which double differential signals were computed, during either voluntary or electrically elicited isometric contractions. For relatively low-level voluntary contractions (10%-30% of maximum force) individual firings of three to four-different motor units were identified and their waveforms were closely approximated by the model. Motor unit parameters such as depth, size, fiber orientation and length, location of innervation and tendonous zones, propagation velocity, and source width were estimated using the model. Two applications of the model are described. The first analyzes the effects of electrode rotation with respect to the muscle fiber direction and shows the possibility of conduction velocity (CV) over- and under-estimation. The second focuses on the myoelectric manifestations of fatigue during a sustained electrically elicited contraction and the interrelationship between muscle fiber CV, spectral and amplitude variables, and the length of the depolarization zone. It is concluded that a) surface EMG detection using an electrode array, when combined with a model of signal propagation, provides a useful method for understanding the physiological and anatomical determinants of EMG waveform characteristics and b) the model provides a way for the interpretation of fatigue plots.

  19. Correlative Evaluation of Mental and Physical Workload of Laparoscopic Surgeons Based on Surface Electromyography and Eye-tracking Signals.

    Science.gov (United States)

    Zhang, Jian-Yang; Liu, Sheng-Lin; Feng, Qing-Min; Gao, Jia-Qi; Zhang, Qiang

    2017-09-11

    Surgeons' mental and physical workloads are major focuses of operating room (OR) ergonomics, and studies on this topic have generally focused on either mental workload or physical workload, ignoring the interaction between them. Previous studies have shown that physically demanding work may affect mental performance and may be accompanied by impaired mental processing and decreased performance. In this study, 14 participants were recruited to perform laparoscopic cholecystectomy (LC) procedures in a virtual simulator. Surface electromyography (sEMG) signals of the bilateral trapezius, bicipital, brachioradialis and flexor carpi ulnaris (FCU) muscles and eye-tracking signals were acquired during the experiment. The results showed that the least square means of muscle activity during the LC phases of surgery in an all-participants mixed effects model were 0.79, 0.81, and 0.98, respectively. The observed muscle activities in the different phases exhibited some similarity, while marked differences were found between the forearm bilateral muscles. Regarding mental workload, significant differences were observed in pupil dilation between the three phases of laparoscopic surgery. The mental and physical workloads of laparoscopic surgeons do not appear to be generally correlated, although a few significant negative correlations were found. This result further indicates that mental fatigue does markedly interfere with surgeons' operating movements.

  20. Random Forest-Based Recognition of Isolated Sign Language Subwords Using Data from Accelerometers and Surface Electromyographic Sensors.

    Science.gov (United States)

    Su, Ruiliang; Chen, Xiang; Cao, Shuai; Zhang, Xu

    2016-01-14

    Sign language recognition (SLR) has been widely used for communication amongst the hearing-impaired and non-verbal community. This paper proposes an accurate and robust SLR framework using an improved decision tree as the base classifier of random forests. This framework was used to recognize Chinese sign language subwords using recordings from a pair of portable devices worn on both arms consisting of accelerometers (ACC) and surface electromyography (sEMG) sensors. The experimental results demonstrated the validity of the proposed random forest-based method for recognition of Chinese sign language (CSL) subwords. With the proposed method, 98.25% average accuracy was obtained for the classification of a list of 121 frequently used CSL subwords. Moreover, the random forests method demonstrated a superior performance in resisting the impact of bad training samples. When the proportion of bad samples in the training set reached 50%, the recognition error rate of the random forest-based method was only 10.67%, while that of a single decision tree adopted in our previous work was almost 27.5%. Our study offers a practical way of realizing a robust and wearable EMG-ACC-based SLR systems.

  1. Surface boxplots

    KAUST Repository

    Genton, Marc G.

    2014-01-22

    In this paper, we introduce a surface boxplot as a tool for visualization and exploratory analysis of samples of images. First, we use the notion of volume depth to order the images viewed as surfaces. In particular, we define the median image. We use an exact and fast algorithm for the ranking of the images. This allows us to detect potential outlying images that often contain interesting features not present in most of the images. Second, we build a graphical tool to visualize the surface boxplot and its various characteristics. A graph and histogram of the volume depth values allow us to identify images of interest. The code is available in the supporting information of this paper. We apply our surface boxplot to a sample of brain images and to a sample of climate model outputs.

  2. Convex surfaces

    CERN Document Server

    Busemann, Herbert

    2008-01-01

    This exploration of convex surfaces focuses on extrinsic geometry and applications of the Brunn-Minkowski theory. It also examines intrinsic geometry and the realization of intrinsic metrics. 1958 edition.

  3. Surface decontamination

    International Nuclear Information System (INIS)

    Silva, S. da; Teixeira, M.V.

    1986-06-01

    The general methods of surface decontamination used in laboratory and others nuclear installations areas, as well as the procedures for handling radioactive materials and surfaces of work are presented. Some methods for decontamination of body external parts are mentioned. The medical supervision and assistance are required for internal or external contamination involving or not lesion in persons. From this medical radiation protection decontamination procedures are determined. (M.C.K.) [pt

  4. Subspace based adaptive denoising of surface EMG from neurological injury patients

    Science.gov (United States)

    Liu, Jie; Ying, Dongwen; Zev Rymer, William; Zhou, Ping

    2014-10-01

    Objective: After neurological injuries such as spinal cord injury, voluntary surface electromyogram (EMG) signals recorded from affected muscles are often corrupted by interferences, such as spurious involuntary spikes and background noises produced by physiological and extrinsic/accidental origins, imposing difficulties for signal processing. Conventional methods did not well address the problem caused by interferences. It is difficult to mitigate such interferences using conventional methods. The aim of this study was to develop a subspace-based denoising method to suppress involuntary background spikes contaminating voluntary surface EMG recordings. Approach: The Karhunen-Loeve transform was utilized to decompose a noisy signal into a signal subspace and a noise subspace. An optimal estimate of EMG signal is derived from the signal subspace and the noise power. Specifically, this estimator is capable of making a tradeoff between interference reduction and signal distortion. Since the estimator partially relies on the estimate of noise power, an adaptive method was presented to sequentially track the variation of interference power. The proposed method was evaluated using both semi-synthetic and real surface EMG signals. Main results: The experiments confirmed that the proposed method can effectively suppress interferences while keep the distortion of voluntary EMG signal in a low level. The proposed method can greatly facilitate further signal processing, such as onset detection of voluntary muscle activity. Significance: The proposed method can provide a powerful tool for suppressing background spikes and noise contaminating voluntary surface EMG signals of paretic muscles after neurological injuries, which is of great importance for their multi-purpose applications.

  5. Surface phonons

    CERN Document Server

    Wette, Frederik

    1991-01-01

    In recent years substantial progress has been made in the detection of surface phonons owing to considerable improvements in inelastic rare gas scattering tech­ niques and electron energy loss spectroscopy. With these methods it has become possible to measure surface vibrations in a wide energy range for all wave vectors in the two-dimensional Brillouin zone and thus to deduce the complete surface phonon dispersion curves. Inelastic atomic beam scattering and electron energy loss spectroscopy have started to play a role in the study of surface phonons similar to the one played by inelastic neutron scattering in the investigation of bulk phonons in the last thirty years. Detailed comparison between experimen­ tal results and theoretical studies of inelastic surface scattering and of surface phonons has now become feasible. It is therefore possible to test and to improve the details of interaction models which have been worked out theoretically in the last few decades. At this point we felt that a concise, co...

  6. Analysis of the sEMG/force relationship using HD-sEMG technique and data fusion: A simulation study.

    Science.gov (United States)

    Al Harrach, Mariam; Carriou, Vincent; Boudaoud, Sofiane; Laforet, Jeremy; Marin, Frederic

    2017-04-01

    The relationship between the surface Electromyogram (sEMG) signal and the force of an individual muscle is still ambiguous due to the complexity of experimental evaluation. However, understanding this relationship should be useful for the assessment of neuromuscular system in healthy and pathological contexts. In this study, we present a global investigation of the factors governing the shape of this relationship. Accordingly, we conducted a focused sensitivity analysis of the sEMG/force relationship form with respect to neural, functional and physiological parameters variation. For this purpose, we used a fast generation cylindrical model for the simulation of an 8×8 High Density-sEMG (HD-sEMG) grid and a twitch based force model for the muscle force generation. The HD-sEMG signals as well as the corresponding force signals were simulated in isometric non-fatiguing conditions and were based on the Biceps Brachii (BB) muscle properties. A total of 10 isometric constant contractions of 5s were simulated for each configuration of parameters. The Root Mean Squared (RMS) value was computed in order to quantify the sEMG amplitude. Then, an image segmentation method was used for data fusion of the 8×8 RMS maps. In addition, a comparative study between recent modeling propositions and the model proposed in this study is presented. The evaluation was made by computing the Normalized Root Mean Squared Error (NRMSE) of their fitting to the simulated relationship functions. Our results indicated that the relationship between the RMS (mV) and muscle force (N) can be modeled using a 3rd degree polynomial equation. Moreover, it appears that the obtained coefficients are patient-specific and dependent on physiological, anatomical and neural parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Ice Surfaces

    Science.gov (United States)

    Shultz, Mary Jane

    2017-05-01

    Ice is a fundamental solid with important environmental, biological, geological, and extraterrestrial impact. The stable form of ice at atmospheric pressure is hexagonal ice, Ih. Despite its prevalence, Ih remains an enigmatic solid, in part due to challenges in preparing samples for fundamental studies. Surfaces of ice present even greater challenges. Recently developed methods for preparation of large single-crystal samples make it possible to reproducibly prepare any chosen face to address numerous fundamental questions. This review describes preparation methods along with results that firmly establish the connection between the macroscopic structure (observed in snowflakes, microcrystallites, or etch pits) and the molecular-level configuration (detected with X-ray or electron scattering techniques). Selected results of probing interactions at the ice surface, including growth from the melt, surface vibrations, and characterization of the quasi-liquid layer, are discussed.

  8. Surfacing Moves

    DEFF Research Database (Denmark)

    Lutz, Peter

    2013-01-01

    such as schedules, machines, and aging bodies. To this end, the article also experiments with ‘surfacing’ as an ethnographic heuristic for figuring these different ‘spatial-timings’. The article concludes that surfacing matters not only in senior home care but also in the field-desks of ethnographic analysis....

  9. Attack surfaces

    DEFF Research Database (Denmark)

    Gruschka, Nils; Jensen, Meiko

    2010-01-01

    The new paradigm of cloud computing poses severe security risks to its adopters. In order to cope with these risks, appropriate taxonomies and classification criteria for attacks on cloud computing are required. In this work-in-progress paper we present one such taxonomy based on the notion...... of attack surfaces of the cloud computing scenario participants....

  10. Extracting Extensor Digitorum Communis Activation Patterns using High-Density Surface Electromyography

    Directory of Open Access Journals (Sweden)

    Xiaogang eHu

    2015-10-01

    Full Text Available The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions.The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7×9 surface electromyogram (EMG recordings. The muscle activation map (based on the root mean square of the EMG was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic. Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

  11. De electricitatis catholici musculari - concerning the electrical properties of muscles, with emphasis on meat quality

    DEFF Research Database (Denmark)

    Ravn, L.S.; Andersen, Ninette Kieme; Rasmussen, M.A.

    2008-01-01

    This study aims to explore the potential of evoked non-invasive surface electromyography (SEMG) analysis, in predicting meat quality traits in livestock. Evoked SEMG is a system that records, transdermally, electrical signals generated in muscle fibres upon external stimulation. These signals are...

  12. Muscle fiber velocity and electromyographic signs of fatigue in fibromyalgia

    NARCIS (Netherlands)

    Klaver-Krol, E.G.; Rasker, J.J.; Henriquez, N.R.; Verheijen, W.G.; Zwarts, M.J.

    2012-01-01

    INTRODUCTION: Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls. METHODS: sEMG was performed on the biceps brachii muscle of 13 women with FM and

  13. Simultaneous 31P NMR spectroscopy and EMG in exercising and recovering human skeletal muscle: technical aspects

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, P; Thomsen, C; Sinkjaer, T

    1994-01-01

    The bioenergetics of human skeletal muscle can be studied by 31P NMR spectroscopy (31P-MRS) and by surface electromyography (SEMG). Simultaneous 31P-MRS and SEMG permit accurate and noninvasive studies of the correlation between metabolic and electrical changes in exercising and recovering human...

  14. Muscle fiber velocity and electromyographic signs of fatigue in fibromyalgia

    NARCIS (Netherlands)

    Klaver-Krol, E.G.; Rasker, Johannes J.; Henriquez, N.R.; Verheijen, W.G.; Zwarts, M.J.

    2012-01-01

    Introduction: Fibromyalgia (FM) is a disorder of widespread muscular pain. We investigated possible differences in surface electromyography (sEMG) in clinically unaffected muscle between patients with FM and controls. Methods: sEMG was performed on the biceps brachii muscle of 13 women with FM and

  15. Influence of hamstring lengthening on muscle activation timing during gait

    NARCIS (Netherlands)

    Buurke, Jaap; Hermens, Hermanus J.; Roetenberg, D.; Harlaar, J.; Rosenbaum, D.; Kleissen, R.F.M.

    2004-01-01

    The purpose of this study was to describe the changes in muscle activation patterns using surface electromyography (sEMG) during walking in patients with cerebral palsy (CP), before and after hamstring lengthening. In the current clinical use of sEMG during walking in CP for pre-operative planning,

  16. Community Gardens as Health Promoters: Effects on Mental and Physical Stress Levels in Adults with and without Mental Disabilities

    Directory of Open Access Journals (Sweden)

    Nugrahaning Sani Dewi

    2017-01-01

    Full Text Available The study focuses on psychological and physical effects of stress while performing community garden activities of various intensity levels. The aim of this study was to determine the psychological and physical effects in adults with (case group and without (control group mental disabilities. Salivary α-amylase (sAA levels and the stress response scale (SRS-18 were used for the psychological analysis (n = 42. For physical assessment (n = 13, electrocardiogram (ECG, surface electromyogram (sEMG, and respiration rate were continuously measured while performing the activities using a multichannel telemetry system. The results showed that following the activities, the case group exhibited decreasing sAA levels while control group exhibited increasing sAA levels. However, both groups exhibited lower SRS-18 results following the activities. Compared with the control group, the case group had a significantly lower increase in the ratio of the heart rate (IRHR (5.5% during low-intensity work (filling pots with soil, but a significantly higher IRHR (16.7% during high-intensity work (turning over soil. The case group experienced significantly higher levels of fatigue during high-intensity work (digging than during the rest condition. These findings indicate that appropriate workload allocation, according to health, is necessary in the community garden setting because reducing the intensity of work assignments for people with mental disabilities will reduce their physical stress.

  17. Surfaces of Building Practice

    OpenAIRE

    Surynková, Petra

    2009-01-01

    My diploma thesis Surfaces of Building Practice deals with the basic properties of surfaces, their mathematical description, categorization, and application in technical practice. Each studied surface is defined and its process of construction and parametrical description is listed. The thesis studies selected types of surfaces in details - these surfaces include surfaces of revolution, ruled surfaces, screw surfaces, and translational surfaces. An application of each studied surfaces is show...

  18. Rough surface

    International Nuclear Information System (INIS)

    Hudina, M.

    1982-08-01

    For the determination of the thermal-hydraulic performances of rough surfaces, the method of evaluation is particularly important. In order to increase confidence in the results, a new evaluation procedure was introduced. This procedure is based on the transformation of simple channel experimental results to equal boundary conditions, and on the suitable application and confirmation of these transformed values in more complicated flow channel geometries. Existing methods, applied to the results obtained in an annular channel, do not fulfil all the transformation requirements. Thus a new, more complete transformation method, which uses the turbulent eddy diffusivity model, was developed. To check the quality of this transformation, within the scope of the new evaluation procedure, the results of experimental investigation in annular channels and in a bundle of hexagonal geometry were used together with the predictions of benchmark calculations. The success of the new method was confirmed by extensive comparisons, with the results of different presently-acknowledged transformations being considered as well. Based on these comparisons an assessment of the individual transformations is given. (Auth.)

  19. On surface approximation using developable surfaces

    DEFF Research Database (Denmark)

    Chen, H. Y.; Lee, I. K.; Leopoldseder, s.

    1999-01-01

    We introduce a method for approximating a given surface by a developable surface. It will be either a G(1) surface consisting of pieces of cones or cylinders of revolution or a G(r) NURBS developable surface. Our algorithm will also deal properly with the problems of reverse engineering and produ...... robust approximation of given scattered data. The presented technique can be applied in computer aided manufacturing, e.g. in shipbuilding. (C) 1999 Academic Press....

  20. On surface approximation using developable surfaces

    DEFF Research Database (Denmark)

    Chen, H. Y.; Lee, I. K.; Leopoldseder, S.

    1998-01-01

    We introduce a method for approximating a given surface by a developable surface. It will be either a G_1 surface consisting of pieces of cones or cylinders of revolution or a G_r NURBS developable surface. Our algorithm will also deal properly with the problems of reverse engineering and produce...... robust approximation of given scattered data. The presented technique can be applied in computer aided manufacturing, e.g. in shipbuilding....

  1. Parametrization of translational surfaces

    OpenAIRE

    Perez-Diaz, Sonia; Shen, Liyong

    2014-01-01

    The algebraic translational surface is a typical modeling surface in computer aided design and architecture industry. In this paper, we give a necessary and sufficient condition for that algebraic surface having a standard parametric representation and our proof is constructive. If the given algebraic surface is translational, then we can compute a standard parametric representation for the surface.

  2. Quantifying forearm muscle activity during wrist and finger movements by means of multi-channel electromyography.

    Directory of Open Access Journals (Sweden)

    Marco Gazzoni

    Full Text Available The study of hand and finger movement is an important topic with applications in prosthetics, rehabilitation, and ergonomics. Surface electromyography (sEMG is the gold standard for the analysis of muscle activation. Previous studies investigated the optimal electrode number and positioning on the forearm to obtain information representative of muscle activation and robust to movements. However, the sEMG spatial distribution on the forearm during hand and finger movements and its changes due to different hand positions has never been quantified. The aim of this work is to quantify 1 the spatial localization of surface EMG activity of distinct forearm muscles during dynamic free movements of wrist and single fingers and 2 the effect of hand position on sEMG activity distribution. The subjects performed cyclic dynamic tasks involving the wrist and the fingers. The wrist tasks and the hand opening/closing task were performed with the hand in prone and neutral positions. A sensorized glove was used for kinematics recording. sEMG signals were acquired from the forearm muscles using a grid of 112 electrodes integrated into a stretchable textile sleeve. The areas of sEMG activity have been identified by a segmentation technique after a data dimensionality reduction step based on Non Negative Matrix Factorization applied to the EMG envelopes. The results show that 1 it is possible to identify distinct areas of sEMG activity on the forearm for different fingers; 2 hand position influences sEMG activity level and spatial distribution. This work gives new quantitative information about sEMG activity distribution on the forearm in healthy subjects and provides a basis for future works on the identification of optimal electrode configuration for sEMG based control of prostheses, exoskeletons, or orthoses. An example of use of this information for the optimization of the detection system for the estimation of joint kinematics from sEMG is reported.

  3. Quantifying forearm muscle activity during wrist and finger movements by means of multi-channel electromyography.

    Science.gov (United States)

    Gazzoni, Marco; Celadon, Nicolò; Mastrapasqua, Davide; Paleari, Marco; Margaria, Valentina; Ariano, Paolo

    2014-01-01

    The study of hand and finger movement is an important topic with applications in prosthetics, rehabilitation, and ergonomics. Surface electromyography (sEMG) is the gold standard for the analysis of muscle activation. Previous studies investigated the optimal electrode number and positioning on the forearm to obtain information representative of muscle activation and robust to movements. However, the sEMG spatial distribution on the forearm during hand and finger movements and its changes due to different hand positions has never been quantified. The aim of this work is to quantify 1) the spatial localization of surface EMG activity of distinct forearm muscles during dynamic free movements of wrist and single fingers and 2) the effect of hand position on sEMG activity distribution. The subjects performed cyclic dynamic tasks involving the wrist and the fingers. The wrist tasks and the hand opening/closing task were performed with the hand in prone and neutral positions. A sensorized glove was used for kinematics recording. sEMG signals were acquired from the forearm muscles using a grid of 112 electrodes integrated into a stretchable textile sleeve. The areas of sEMG activity have been identified by a segmentation technique after a data dimensionality reduction step based on Non Negative Matrix Factorization applied to the EMG envelopes. The results show that 1) it is possible to identify distinct areas of sEMG activity on the forearm for different fingers; 2) hand position influences sEMG activity level and spatial distribution. This work gives new quantitative information about sEMG activity distribution on the forearm in healthy subjects and provides a basis for future works on the identification of optimal electrode configuration for sEMG based control of prostheses, exoskeletons, or orthoses. An example of use of this information for the optimization of the detection system for the estimation of joint kinematics from sEMG is reported.

  4. Cryogenic Selective Surfaces

    Data.gov (United States)

    National Aeronautics and Space Administration — Selective surfaces have wavelength dependent emissivity/absorption. These surfaces can be designed to reflect solar radiation, while maximizing infrared emittance,...

  5. Characterization of solid surfaces

    National Research Council Canada - National Science Library

    Kane, Philip F; Larrabee, Graydon B

    1974-01-01

    .... A comprehensive review of surface analysis, this important volume surveys both principles and techniques of surface characterization, describes instrumentation, and suggests the course of future research...

  6. Open algebraic surfaces

    CERN Document Server

    Miyanishi, Masayoshi

    2000-01-01

    Open algebraic surfaces are a synonym for algebraic surfaces that are not necessarily complete. An open algebraic surface is understood as a Zariski open set of a projective algebraic surface. There is a long history of research on projective algebraic surfaces, and there exists a beautiful Enriques-Kodaira classification of such surfaces. The research accumulated by Ramanujan, Abhyankar, Moh, and Nagata and others has established a classification theory of open algebraic surfaces comparable to the Enriques-Kodaira theory. This research provides powerful methods to study the geometry and topology of open algebraic surfaces. The theory of open algebraic surfaces is applicable not only to algebraic geometry, but also to other fields, such as commutative algebra, invariant theory, and singularities. This book contains a comprehensive account of the theory of open algebraic surfaces, as well as several applications, in particular to the study of affine surfaces. Prerequisite to understanding the text is a basic b...

  7. Surfaces with Natural Ridges

    DEFF Research Database (Denmark)

    Brander, David; Markvorsen, Steen

    2015-01-01

    We discuss surfaces with singularities, both in mathematics and in the real world. For many types of mathematical surface, singularities are natural and can be regarded as part of the surface. The most emblematic example is that of surfaces of constant negative Gauss curvature, all of which neces...

  8. Weyl nodal surfaces

    Science.gov (United States)

    Türker, Oǧuz; Moroz, Sergej

    2018-02-01

    We consider three-dimensional fermionic band theories that exhibit Weyl nodal surfaces defined as two-band degeneracies that form closed surfaces in the Brillouin zone. We demonstrate that topology ensures robustness of these objects under small perturbations of a Hamiltonian. This topological robustness is illustrated in several four-band models that exhibit nodal surfaces protected by unitary or antiunitary symmetries. Surface states and Nielsen-Ninomiya doubling of nodal surfaces are also investigated.

  9. Surface Topography Hinders Bacterial Surface Motility.

    Science.gov (United States)

    Chang, Yow-Ren; Weeks, Eric R; Ducker, William A

    2018-03-21

    We demonstrate that the surface motility of the bacterium, Pseudomonas aeruginosa, is hindered by a crystalline hemispherical topography with wavelength in the range of 2-8 μm. The motility was determined by the analysis of time-lapse microscopy images of cells in a flowing growth medium maintained at 37 °C. The net displacement of bacteria over 5 min is much lower on surfaces containing 2-8 μm hemispheres than on flat topography, but displacement on the 1 μm hemispheres is not lower. That is, there is a threshold between 1 and 2 μm for response to the topography. Cells on the 4 μm hemispheres were more likely to travel parallel to the local crystal axis than in other directions. Cells on the 8 μm topography were less likely to travel across the crowns of the hemispheres and were also more likely to make 30°-50° turns than on flat surfaces. These results show that surface topography can act as a significant barrier to surface motility and may therefore hinder surface exploration by bacteria. Because surface exploration can be a part of the process whereby bacteria form colonies and seek nutrients, these results help to elucidate the mechanism by which surface topography hinders biofilm formation.

  10. SURFACE PHOTOMETRY OF LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    DEBLOK, WJG; VANDERHULST, JM; BOTHUN, GD

    1995-01-01

    Low surface brightness (LSB) galaxies are galaxies dominated by an exponential disc whose central surface brightness is much fainter than the value of mu(B)(0) = 21.65 +/- 0.30 mag arcsec(-2) found by Freeman. In this paper we present broadband photometry of a sample of 21 late-type LSB galaxies.

  11. [A field study on the work load and muscle fatigue at neck-shoulder in female sewing machine operators by using surface electromyography].

    Science.gov (United States)

    Zhang, Fei-ruo; Wang, Sheng; He, Li-hua; Zhang, Ying; Wu, Shan-shan; Li, Jing-yun; Hu, Guang-yi; Ye, Kang-ping

    2011-03-01

    To study neck and shoulder work-related muscle fatigue of female sewing machine operators. 18 health female sewing machine operators without musculoskeletal disorders work in Beijing garment industry factory as volunteers in participate of this study. The maximal voluntary contraction (MVC) and 20% MVC of bilateral upper trapezium and cervical erectors spinae was tested before sewing operations, then the whole 20 time windows (1 time window = 10 min) sewing machine operations was monitored and the surface electromyography (sEMG) signals simultaneously was recorded after monitoring the 20%MVC was tested. Use amplitude analysis method to reduction recorded EMG signals. During work, the median load for the left cervical erector spinae (LCES), right cervical erector spinae (RCES), left upper trapezium (LUT) and right upper trapezium (RUT) respectively was 6.78 ± 1.05, 6.94 ± 1.12, 5.68 ± 2.56 and 6.47 ± 3.22, work load of right is higher than the left; static load analysis indicated the value of RMS(20%MVC) before work was higher than that value after work, the increase of right CES and UT RMS(20%MVC) was more; the largest 20%MVE of bilateral CES occurred at 20th time window, and that of bilateral UT happened at 16th. The work load of female sewing machine operators is sustained "static" load, and work load of right neck-shoulder is higher than left, right neck-shoulder muscle is more fatigable and much serious once fatigued.

  12. Computer aided surface representation

    Energy Technology Data Exchange (ETDEWEB)

    Barnhill, R E

    1987-11-01

    The aims of this research are the creation of new surface forms and the determination of geometric and physical properties of surfaces. The full sweep from constructive mathematics through the implementation of algorithms and the interactive computer graphics display of surfaces is utilized. Both three-dimensional and multi- dimensional surfaces are considered. Particular emphasis is given to the scientific computing solution of Department of Energy problems. The methods that we have developed and that we are proposing to develop allow applications such as: Producing smooth contour maps from measured data, such as weather maps. Modeling the heat distribution inside a furnace from sample measurements. Terrain modeling based on satellite pictures. The investigation of new surface forms includes the topics of triangular interpolants, multivariate interpolation, surfaces defined on surfaces and monotone and/or convex surfaces. The geometric and physical properties considered include contours, the intersection of surfaces, curvatures as a interrogation tool, and numerical integration.

  13. Mechanics of active surfaces

    Science.gov (United States)

    Salbreux, Guillaume; Jülicher, Frank

    2017-09-01

    We derive a fully covariant theory of the mechanics of active surfaces. This theory provides a framework for the study of active biological or chemical processes at surfaces, such as the cell cortex, the mechanics of epithelial tissues, or reconstituted active systems on surfaces. We introduce forces and torques acting on a surface, and derive the associated force balance conditions. We show that surfaces with in-plane rotational symmetry can have broken up-down, chiral, or planar-chiral symmetry. We discuss the rate of entropy production in the surface and write linear constitutive relations that satisfy the Onsager relations. We show that the bending modulus, the spontaneous curvature, and the surface tension of a passive surface are renormalized by active terms. Finally, we identify active terms which are not found in a passive theory and discuss examples of shape instabilities that are related to active processes in the surface.

  14. Advanced Surface Technology

    DEFF Research Database (Denmark)

    Møller, Per; Nielsen, Lars Pleht

    This new significant book on advanced modern surface technology in all its variations, is aimed at both teaching at engineering schools and practical application in industry. The work covers all the significant aspects of modern surface technology and also describes how new advanced techniques make...... of the components. It covers everything from biocompatible surfaces of IR absorbent or reflective surfaces to surfaces with specific properties within low friction, hardness, corrosion, colors, etc. The book includes more than 400 pages detailing virtually all analysis methods for examining at surfaces....

  15. Regularity of Minimal Surfaces

    CERN Document Server

    Dierkes, Ulrich; Tromba, Anthony J; Kuster, Albrecht

    2010-01-01

    "Regularity of Minimal Surfaces" begins with a survey of minimal surfaces with free boundaries. Following this, the basic results concerning the boundary behaviour of minimal surfaces and H-surfaces with fixed or free boundaries are studied. In particular, the asymptotic expansions at interior and boundary branch points are derived, leading to general Gauss-Bonnet formulas. Furthermore, gradient estimates and asymptotic expansions for minimal surfaces with only piecewise smooth boundaries are obtained. One of the main features of free boundary value problems for minimal surfaces is t

  16. Differential contributions of ankle plantarflexors during submaximal isometric muscle action

    DEFF Research Database (Denmark)

    Masood, Tahir; Bojsen-Møller, Jens; Kalliokoski, Kari K

    2014-01-01

    The objective of this study was to investigate the relative contributions of superficial and deep ankle plantarflexors during repetitive submaximal isometric contractions using surface electromyography (SEMG) and positron emission tomography (PET). Myoelectric signals were obtained from twelve...

  17. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  18. Smooth polyhedral surfaces

    KAUST Repository

    Günther, Felix

    2017-03-15

    Polyhedral surfaces are fundamental objects in architectural geometry and industrial design. Whereas closeness of a given mesh to a smooth reference surface and its suitability for numerical simulations were already studied extensively, the aim of our work is to find and to discuss suitable assessments of smoothness of polyhedral surfaces that only take the geometry of the polyhedral surface itself into account. Motivated by analogies to classical differential geometry, we propose a theory of smoothness of polyhedral surfaces including suitable notions of normal vectors, tangent planes, asymptotic directions, and parabolic curves that are invariant under projective transformations. It is remarkable that seemingly mild conditions significantly limit the shapes of faces of a smooth polyhedral surface. Besides being of theoretical interest, we believe that smoothness of polyhedral surfaces is of interest in the architectural context, where vertices and edges of polyhedral surfaces are highly visible.

  19. Integrated Surface Dataset (Global)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Integrated Surface (ISD) Dataset (ISD) is composed of worldwide surface weather observations from over 35,000 stations, though the best spatial coverage is...

  20. Surface Prognostic Charts

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface Prognostic Charts are historical surface prognostic (forecast) charts created by the United States Weather Bureau. They include fronts, isobars, cloud, and...

  1. Advanced Surface Technology

    DEFF Research Database (Denmark)

    Møller, Per; Nielsen, Lars Pleht

    of the components. It covers everything from biocompatible surfaces of IR absorbent or reflective surfaces to surfaces with specific properties within low friction, hardness, corrosion, colors, etc. The book includes more than 400 pages detailing virtually all analysis methods for examining at surfaces.......This new significant book on advanced modern surface technology in all its variations, is aimed at both teaching at engineering schools and practical application in industry. The work covers all the significant aspects of modern surface technology and also describes how new advanced techniques make...... it possible to examine surfaces all the way down to their atomic layers and also to perform realistic durability tests. The many surface techniques are described in clear and simple language, and the book is richly illustrated with detailed drawings and photos. It also deals with replacing environmentally...

  2. Apollo Surface Panoramas

    Data.gov (United States)

    National Aeronautics and Space Administration — Apollo Surface Panoramas is a digital library of photographic panoramas that the Apollo astronauts took while exploring the Moon's surface. These images provide a...

  3. Biomaterials surface science

    CERN Document Server

    Taubert, Andreas; Rodriguez-Cabello, José Carlos

    2013-01-01

    The book provides an overview of the highly interdisciplinary field of surface science in the context of biological and biomedical applications. The covered topics range from micro- and nanostructuring for imparting functionality in a top-down manner to the bottom-up fabrication of gradient surfaces by self-assembly, from interfaces between biomaterials and living matter to smart, stimuli-responsive surfaces, and from cell and surface mechanics to the elucidation of cell-chip interactions in biomedical devices.

  4. Surface and Interface Characterisation

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    2006-01-01

    Surface physical analysis, i.e. topography characterisation, encompasses measurement, visualisation, and quantification. This is critical for both component form and for surface finish at macro-, micro- and nano-scales. The principal methods of surface topography measurement are stylus profilometry...

  5. Modeling conoid surfaces

    OpenAIRE

    Velimirović Ljubica S.; Stanković Mića S.; Radivojević Grozdana

    2002-01-01

    In tins paper we consider conoid surfaces as frequently used surfaces in building techniques, mainly as daring roof structures. Different types of conoids are presented using the programme package Mathematica. We describe the generation of conoids and by means of parametric representation we get their graphics. The geometric approach offers a wide range of possibilities in the research of complicated spatial surface systems.

  6. Surface optical vortices

    Science.gov (United States)

    Lembessis, V. E.; Babiker, M.; Andrews, D. L.

    2009-01-01

    It is shown how the total internal reflection of orbital-angular-momentum-endowed light can lead to the generation of evanescent light possessing rotational properties in which the intensity distribution is firmly localized in the vicinity of the surface. The characteristics of these surface optical vortices depend on the form of the incident light and on the dielectric mismatch of the two media. The interference of surface optical vortices is shown to give rise to interesting phenomena, including pattern rotation akin to a surface optical Ferris wheel. Applications are envisaged to be in atom lithography, optical surface tweezers, and spanners.

  7. Surface cleanliness measurement procedure

    Science.gov (United States)

    Schroder, Mark Stewart; Woodmansee, Donald Ernest; Beadie, Douglas Frank

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  8. Surface for dummies

    CERN Document Server

    Rathbone, Andy

    2014-01-01

    Make Microsoft's Surface work-and play-just the way you want it to Microsoft's Surface tablet has the features and personality you're looking for, with a robust environment for business computing that doesn't skimp on fun. Surface for Dummies, 2nd Edition explains how Windows 8.1 Pro and Windows RT differ, and helps you decide which Surface model is best for you. Step by step, this book walks you through both the hardware and software features of the Surface, including the touch cover and type cover, Windows RT and Windows 8.1 Pro operating systems, and the coveted Office Home & Student 2013 s

  9. Evidence of long term muscle fatigue following prolonged intermittent contractions based on mechano- and electromyograms

    DEFF Research Database (Denmark)

    Søgaard, K; Blangsted, A K; Jørgensen, L V

    2003-01-01

    performance of the biceps muscle are more strongly reflected in low than in high force test contractions, more prominent in the MMG than in the EMG signal and less pronounced following contractions controlled by visual compared to proprioceptive feedback. Further, it was investigated if fatigue induced by 30...... min intermittent contractions at 30% as well as 10% of maximal voluntary contraction (MVC) lasted more than 30 min recovery. In six male subjects the EMG and MMG were recorded from the biceps brachii muscle during three sessions with fatiguing exercise at 10% with visual feedback and at 30% MVC...

  10. Comparison between approximate entropy, correntropy and time reversibility: application to uterine electromyogram signals.

    Science.gov (United States)

    Hassan, Mahmoud; Terrien, Jérémy; Marque, Catherine; Karlsson, Brynjar

    2011-10-01

    Detection of nonlinearity should be the first step before any analysis of nonlinearity or nonlinear behavior in biological signal. The question is which method should be used in each case and which one can best respect the different characteristics of the signals under investigation. In this paper we compare three methods widely used in nonlinearity detection: approximate entropy, correntropy and time reversibility. The false alarm rates with the numbers of surrogates for the three methods were computed on linear, nonlinear stationary and nonlinear nonstationary signals. The results indicate the superiority of time reversibility over the other methods for detecting linearity and nonlinearity in different signal types. The application of time reversibility on uterine electromyographic signal showed very good performance in classifying pregnancy and labor signals. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

  11. On rationally supported surfaces

    DEFF Research Database (Denmark)

    Gravesen, Jens; Juttler, B.; Sir, Z.

    2008-01-01

    We analyze the class of surfaces which are equipped with rational support functions. Any rational support function can be decomposed into a symmetric (even) and an antisymmetric (odd) part. We analyze certain geometric properties of surfaces with odd and even rational support functions....... In particular it is shown that odd rational support functions correspond to those rational surfaces which can be equipped with a linear field of normal vectors, which were discussed by Sampoli et al. (Sampoli, M.L., Peternell, M., Juttler, B., 2006. Rational surfaces with linear normals and their convolutions...... with rational surfaces. Comput. Aided Geom. Design 23, 179-192). As shown recently, this class of surfaces includes non-developable quadratic triangular Bezier surface patches (Lavicka, M., Bastl, B., 2007. Rational hypersurfaces with rational convolutions. Comput. Aided Geom. Design 24, 410426; Peternell, M...

  12. Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise

    Directory of Open Access Journals (Sweden)

    Petras Ražanskas

    2015-08-01

    Full Text Available This article presents a study of the relationship between electromyographic (EMG signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R2 = 0:77 to R2 = 0:98 (for blood lactate and from R2 = 0:81 to R2 = 0:97 (for oxygen uptake were obtained when using random forest regressors.

  13. Methodological aspects of SEMG recordings for force estimation--a tutorial and review

    NARCIS (Netherlands)

    Staudenmann, D.; Roeleveld, K.; Stegeman, D.F.; van Dieen, J.H.

    2010-01-01

    Insight into the magnitude of muscle forces is important in biomechanics research, for example because muscle forces are the main determinants of joint loading. Unfortunately muscle forces cannot be calculated directly and can only be measured using invasive procedures. Therefore, estimates of

  14. Methodological aspects of SEMG recordings for force estimation--a tutorial and review.

    NARCIS (Netherlands)

    Staudenmann, D.; Roeleveld, K.; Stegeman, D.F.; Dieën, J.H. van

    2010-01-01

    Insight into the magnitude of muscle forces is important in biomechanics research, for example because muscle forces are the main determinants of joint loading. Unfortunately muscle forces cannot be calculated directly and can only be measured using invasive procedures. Therefore, estimates of

  15. Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise.

    Science.gov (United States)

    Ražanskas, Petras; Verikas, Antanas; Olsson, Charlotte; Viberg, Per-Arne

    2015-08-19

    This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R(2) = 0:77 to R(2) = 0:98 (for blood lactate) and from R(2) = 0:81 to R(2) = 0:97 (for oxygen uptake) were obtained when using random forest regressors.

  16. DNA ELECTROPHORESIS AT SURFACES

    Energy Technology Data Exchange (ETDEWEB)

    RAFAILOVICH, MIRIAM; SOKOLOV, JONATHAN; GERSAPPE, DILIP

    2003-09-01

    During this year we performed two major projects: I. We developed a detailed theoretical model which complements our experiments on surface DNA electrophoresis. We found that it was possible to enhance the separation of DNA chains by imposing a chemical nanoscale pattern on the surface. This approach utilized the surface interaction effect of the DNA chains with the substrate and is a refinement to our previous method in which DNA chains were separated on homogeneous flat surfaces. By introducing the nano-patterns on the surface, the conformational changes of DNA chains of different lengths can be amplified, which results in the different friction strengths with the substrate surface. Our results also show that, when compared to the DNA electrophoresis performed on homogeneous flat surfaces, nanopatterned surfaces offer a larger window in choosing different surface interactions to achieve separation. II. In collaboration with a large international manufacturer of skin care products we also embarked on a project involving photo toxicity of titanium dioxide nanoparticles, which are a key ingredient in sunscreen and cosmetic lotions. The results clearly implicated the nanoparticles in catalyzing damage to chromosomal DNA. We then used this knowledge to develop a polymer/anti-oxidant coating which prevented the photocatalytic reaction on DNA while still retaining the UV absorptive properties of the nanoparticles. The standard gel electrophoresis was not sufficient in determining the extent of the DNA damage. The conclusions of this study were based predominantly on analysis obtained with the surface electrophoresis method.

  17. Mirror reactor surface study

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A. L.; Damm, C. C.; Futch, A. H.; Hiskes, J. R.; Meisenheimer, R. G.; Moir, R. W.; Simonen, T. C.; Stallard, B. W.; Taylor, C. E.

    1976-09-01

    A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included.

  18. Laser-surface interactions

    CERN Document Server

    Ganeev, Rashid A

    2014-01-01

    This book is about the interaction of laser radiation with various surfaces at variable parameters of radiation. As a basic principle of classification we chose the energetic or intensity level of interaction of laser radiation with the surfaces. These two characteristics of laser radiation are the most important parameters defining entire spectrum of the processes occurring on the surfaces during interaction with electromagnetic waves. This is a first book containing a whole spectrum of the laser-surface interactions distinguished by the ranges of used laser intensity. It combines the surface response starting from extremely weak laser intensities (~1 W cm-2) up to the relativistic intensities (~1020 W cm-2 and higher). The book provides the basic information about lasers and acquaints the reader with both common applications of laser-surface interactions (laser-related printers, scanners, barcode readers, discs, material processing, military, holography, medicine, etc) and unusual uses of the processes on t...

  19. Mirror reactor surface study

    International Nuclear Information System (INIS)

    Hunt, A.L.; Damm, C.C.; Futch, A.H.; Hiskes, J.R.; Meisenheimer, R.G.; Moir, R.W.; Simonen, T.C.; Stallard, B.W.; Taylor, C.E.

    1976-01-01

    A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included

  20. Electrostatics of patchy surfaces.

    Science.gov (United States)

    Adar, Ram M; Andelman, David; Diamant, Haim

    2017-09-01

    In the study of colloidal, biological and electrochemical systems, it is customary to treat surfaces, macromolecules and electrodes as homogeneously charged. This simplified approach is proven successful in most cases, but fails to describe a wide range of heterogeneously charged surfaces commonly used in experiments. For example, recent experiments have revealed a long-range attraction between overall neutral surfaces, locally charged in a mosaic-like structure of positively and negatively charged domains ("patches"). Here, we review experimental and theoretical studies addressing the stability of heterogeneously charged surfaces, their effect on ionic profiles in solution, and the interaction between two such surfaces. We focus on electrostatics, and highlight the important new physical parameters appearing in the heterogeneous case, such as the largest patch size and inter-surface charge correlations. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Hydrodynamic Vortex on Surfaces

    Science.gov (United States)

    Ragazzo, Clodoaldo Grotta; de Barros Viglioni, Humberto Henrique

    2017-10-01

    The equations of motion for a system of point vortices on an oriented Riemannian surface of finite topological type are presented. The equations are obtained from a Green's function on the surface. The uniqueness of the Green's function is established under hydrodynamic conditions at the surface's boundaries and ends. The hydrodynamic force on a point vortex is computed using a new weak formulation of Euler's equation adapted to the point vortex context. An analogy between the hydrodynamic force on a massive point vortex and the electromagnetic force on a massive electric charge is presented as well as the equations of motion for massive vortices. Any noncompact Riemann surface admits a unique Riemannian metric such that a single vortex in the surface does not move ("Steady Vortex Metric"). Some examples of surfaces with steady vortex metric isometrically embedded in R^3 are presented.

  2. Ruled Laguerre minimal surfaces

    KAUST Repository

    Skopenkov, Mikhail

    2011-10-30

    A Laguerre minimal surface is an immersed surface in ℝ 3 being an extremal of the functional ∫ (H 2/K-1)dA. In the present paper, we prove that the only ruled Laguerre minimal surfaces are up to isometry the surfaces ℝ (φλ) = (Aφ, Bφ, Cφ + D cos 2φ) + λ(sin φ, cos φ, 0), where A,B,C,D ε ℝ are fixed. To achieve invariance under Laguerre transformations, we also derive all Laguerre minimal surfaces that are enveloped by a family of cones. The methodology is based on the isotropic model of Laguerre geometry. In this model a Laguerre minimal surface enveloped by a family of cones corresponds to a graph of a biharmonic function carrying a family of isotropic circles. We classify such functions by showing that the top view of the family of circles is a pencil. © 2011 Springer-Verlag.

  3. Surface optical vortices

    OpenAIRE

    Lembessis, V. E.; Babiker, M.; Andrews, D L.

    2009-01-01

    It is shown how the total internal reflection of orbital-angular-momentum-endowed light can lead to the generation of evanescent light possessing rotational properties in which the intensity distribution is firmly localized in the vicinity of the surface. The characteristics of these surface optical vortices depend on the form of the incident light and on the dielectric mismatch of the two media. The interference of surface optical vortices is shown to give rise to interesting phenomena, incl...

  4. Encyclopedia of analytical surfaces

    CERN Document Server

    Krivoshapko, S N

    2015-01-01

    This encyclopedia presents an all-embracing collection of analytical surface classes. It provides concise definitions  and description for more than 500 surfaces and categorizes them in 38 classes of analytical surfaces. All classes are cross references to the original literature in an excellent bibliography. The encyclopedia is of particular interest to structural and civil engineers and serves as valuable reference for mathematicians.

  5. Surface science and catalysis

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1985-02-01

    Modern surface science studies have explored a large number of metal catalyst systems. Three classes of catalytic reactions can be identified: (1) those that occur over the metal surface; (2) reactions that take place on top of a strongly adsorbed overlayer and (3) reactions that occur on co-adsorbate modified surfaces. Case histories for each class are presented. 44 refs., 13 figs., 3 tabs

  6. Water at surfaces with tunable surface chemistries

    Science.gov (United States)

    Sanders, Stephanie E.; Vanselous, Heather; Petersen, Poul B.

    2018-03-01

    Aqueous interfaces are ubiquitous in natural environments, spanning atmospheric, geological, oceanographic, and biological systems, as well as in technical applications, such as fuel cells and membrane filtration. Where liquid water terminates at a surface, an interfacial region is formed, which exhibits distinct properties from the bulk aqueous phase. The unique properties of water are governed by the hydrogen-bonded network. The chemical and physical properties of the surface dictate the boundary conditions of the bulk hydrogen-bonded network and thus the interfacial properties of the water and any molecules in that region. Understanding the properties of interfacial water requires systematically characterizing the structure and dynamics of interfacial water as a function of the surface chemistry. In this review, we focus on the use of experimental surface-specific spectroscopic methods to understand the properties of interfacial water as a function of surface chemistry. Investigations of the air-water interface, as well as efforts in tuning the properties of the air-water interface by adding solutes or surfactants, are briefly discussed. Buried aqueous interfaces can be accessed with careful selection of spectroscopic technique and sample configuration, further expanding the range of chemical environments that can be probed, including solid inorganic materials, polymers, and water immiscible liquids. Solid substrates can be finely tuned by functionalization with self-assembled monolayers, polymers, or biomolecules. These variables provide a platform for systematically tuning the chemical nature of the interface and examining the resulting water structure. Finally, time-resolved methods to probe the dynamics of interfacial water are briefly summarized before discussing the current status and future directions in studying the structure and dynamics of interfacial water.

  7. Super Riemann surfaces

    International Nuclear Information System (INIS)

    Rabin, J.M.

    1986-10-01

    A mathematically rigorous notion of supermanifold is presented and used to develop the theory of super Riemann surfaces. Super Riemann surfaces describe superconformal equivalence classes of supergravity geometries in two dimensions and therefore provide a powerful formalism for studying fermionic string theory. They also provide a convenient description of spin structures and half-forms on ordinary Riemann surfaces. I prove the uniformization theorem for super Riemann surfaces, determine the dimension and global structure of super Teichmueller space, and show that the super modular group is isomorphic to the ordinary modular (mapping class) group. Quasisuperconformal mappings and the super Beltrami equations are briefly discussed. 32 refs

  8. Surface science an introduction

    CERN Document Server

    Hudson, John

    1991-01-01

    The whole field of surface science is covered in this work. Starting with a description of the structure and thermodynamics of clean surfaces, the book goes on to discuss kinetic theory of gases and molecular beam formation. This is followed by a largesection on gas-surface interactions, and another major section on energetic particle-surface interactions. The final chapter provides the background to crystal nucleation and growth. The approach adopted is interdisciplinary and slanted towards theexperimental side, with practical analytical techniques being used to illustrate general princi

  9. Surface chemistry essentials

    CERN Document Server

    Birdi, K S

    2013-01-01

    Surface chemistry plays an important role in everyday life, as the basis for many phenomena as well as technological applications. Common examples range from soap bubbles, foam, and raindrops to cosmetics, paint, adhesives, and pharmaceuticals. Additional areas that rely on surface chemistry include modern nanotechnology, medical diagnostics, and drug delivery. There is extensive literature on this subject, but most chemistry books only devote one or two chapters to it. Surface Chemistry Essentials fills a need for a reference that brings together the fundamental aspects of surface chemistry w

  10. Anodized dental implant surface

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Mishra

    2017-01-01

    Full Text Available Purpose: Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. Materials and Methods: A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. Results: The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. Conclusions: The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

  11. Stiction in surface micromachining

    NARCIS (Netherlands)

    Tas, Niels Roelof; Sonnenberg, A.H.; Jansen, Henricus V.; Legtenberg, R.; Legtenberg, Rob; Elwenspoek, Michael Curt

    1996-01-01

    Due to the smoothness of the surfaces in surface micromachining, large adhesion forces between fabricated structures and the substrate are encountered. Four major adhesion mechanisms have been analysed: capillary forces, hydrogen bridging, electrostatic forces and van der Waals forces. Once contact

  12. Biocompatible implant surface treatments

    Directory of Open Access Journals (Sweden)

    Bikash Pattanaik

    2012-01-01

    Limitation of this study is that we tried to give a broader overview related to implant surface treatments. It does not give any conclusion regarding the best biocompatible implant surface treatment investigated till date. Unfortunately, the eventually selected studies were too heterogeneous for inference of data.

  13. Solar absorption surface panel

    Science.gov (United States)

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  14. Response Surface Methodology

    NARCIS (Netherlands)

    Kleijnen, Jack P.C.

    2014-01-01

    Abstract: This chapter first summarizes Response Surface Methodology (RSM), which started with Box and Wilson’s article in 1951 on RSM for real, non-simulated systems. RSM is a stepwise heuristic that uses first-order polynomials to approximate the response surface locally. An estimated polynomial

  15. Response surface methodolgy

    NARCIS (Netherlands)

    Kleijnen, J.P.C.; Fu, Michael C.

    2015-01-01

    This chapter first summarizes Response Surface Methodology (RSM), which started with Box and Wilson’s 1951 article on RSM for real, non-simulated systems. RSM is a stepwise heuristic that uses first-order polynomials to approximate the response surface locally. An estimated polynomial metamodel

  16. Surface tritium contamination studies

    International Nuclear Information System (INIS)

    Sienkiewicz, C.J.

    1986-01-01

    Glovebox wipe surveys were conducted to correlate surface tritium contamination with atmospheric tritium levels. Surface contamination was examined as a function of tritium concentration and limited to the HT/T 2 form. The previously predicted relationship between atmospheric HTO concentration and cleanup times was examined in order to predict a model for atmospheric detritiation of stainless steel enclosures. 2 figures, 2 tables

  17. Sperm Surface Proteomics 2

    NARCIS (Netherlands)

    Brewis, I.A.; Gadella, B.M.|info:eu-repo/dai/nl/115389873

    2017-01-01

    This contribution will focus exclusively on the total (global) protein composition (the proteome) of the sperm surface. Immune responses directed towards sperm surface proteins may cause infertility since functionally intact sperm are under immune attack. The immune attack can be achieved directly

  18. Pseudospherical surfaces with singularities

    DEFF Research Database (Denmark)

    Brander, David

    2017-01-01

    We study a generalization of constant Gauss curvature −1 surfaces in Euclidean 3-space, based on Lorentzian harmonic maps, that we call pseudospherical frontals. We analyse the singularities of these surfaces, dividing them into those of characteristic and non-characteristic type. We give methods...

  19. Surface Loving and Surface Avoiding modes

    OpenAIRE

    Combe, Nicolas; Huntzinger, Jean Roch; Morillo, Joseph

    2008-01-01

    International audience; We theoretically study the propagation of sound waves in GaAs/AlAs superlattices focussing on periodic modes in the vicinity of the band gaps. Based on analytical and numerical calculations, we show that these modes are the product of a quickly oscillating function times a slowly varying envelope function. We carefully study the phase of the envelope function compared to the surface of a semi-infinite superlattice. Especially, the dephasing of the superlattice compared...

  20. Workbench surface editor of brain cortical surface

    Science.gov (United States)

    Dow, Douglas E.; Nowinski, Wieslaw L.; Serra, Luis

    1996-04-01

    We have developed a 3D reach-in tool to manually reconstruct 3D cortical surface patches from 2D brain atlas images. The first application of our cortex editor is building 3D functional maps, specifically Brodmann's areas. This tool may also be useful in clinical practice to adjust incorrectly mapped atlas regions due to the deforming effect of lesions. The cortex editor allows a domain expert to control the correlation of control points across slices. Correct correlation has been difficult for 3D reconstruction algorithms because the atlas slices are far apart and because of the complex topology of the cortex which differs so much from slice to slice. Also, higher precision of the resulting surfaces is demanded since these define 3D brain atlas features upon which future stereotactic surgery may be based. The cortex editor described in this paper provides a tool suitable for a domain expert to use in defining the 3D surface of a Brodmann's area.

  1. Surface preparation of niobium

    International Nuclear Information System (INIS)

    Kneisel, P.

    1980-01-01

    Any discussion of surface preparation for superconducting rf-surfaces is certainly connected with the question what is the best recipe for achieving high Q-values and high break-down fields. Since the break-down in a cavity is not understood so far and because several mechanisms play a role, it also is not possible to give one recipe which always works. Nevertheless in the past certain preparation techniques for niobium surfaces have been developed and certain rules for preparation can be applied. In the following the to-days state of the art will be described and it is attempted to give a short description of the surface in conjunction with the methods of surface treatments, which generally can be applied to niobium cavities. (orig./WTR)

  2. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

  3. Defects at oxide surfaces

    CERN Document Server

    Thornton, Geoff

    2015-01-01

    This book presents the basics and characterization of defects at oxide surfaces. It provides a state-of-the-art review of the field, containing information to the various types of surface defects, describes analytical methods to study defects, their chemical activity and the catalytic reactivity of oxides. Numerical simulations of defective structures complete the picture developed. Defects on planar surfaces form the focus of much of the book, although the investigation of powder samples also form an important part. The experimental study of planar surfaces opens the possibility of applying the large armoury of techniques that have been developed over the last half-century to study surfaces in ultra-high vacuum. This enables the acquisition of atomic level data under well-controlled conditions, providing a stringent test of theoretical methods. The latter can then be more reliably applied to systems such as nanoparticles for which accurate methods of characterization of structure and electronic properties ha...

  4. Super Riemann surfaces

    International Nuclear Information System (INIS)

    Rogers, Alice

    1990-01-01

    A super Riemann surface is a particular kind of (1,1)-dimensional complex analytic supermanifold. From the point of view of super-manifold theory, super Riemann surfaces are interesting because they furnish the simplest examples of what have become known as non-split supermanifolds, that is, supermanifolds where the odd and even parts are genuinely intertwined, as opposed to split supermanifolds which are essentially the exterior bundles of a vector bundle over a conventional manifold. However undoubtedly the main motivation for the study of super Riemann surfaces has been their relevance to the Polyakov quantisation of the spinning string. Some of the papers on super Riemann surfaces are reviewed. Although recent work has shown all super Riemann surfaces are algebraic, some areas of difficulty remain. (author)

  5. Materials and optimized designs for human-machine interfaces via epidermal electronics.

    Science.gov (United States)

    Jeong, Jae-Woong; Yeo, Woon-Hong; Akhtar, Aadeel; Norton, James J S; Kwack, Young-Jin; Li, Shuo; Jung, Sung-Young; Su, Yewang; Lee, Woosik; Xia, Jing; Cheng, Huanyu; Huang, Yonggang; Choi, Woon-Seop; Bretl, Timothy; Rogers, John A

    2013-12-17

    Thin, soft, and elastic electronics with physical properties well matched to the epidermis can be conformally and robustly integrated with the skin. Materials and optimized designs for such devices are presented for surface electromyography (sEMG). The findings enable sEMG from wide ranging areas of the body. The measurements have quality sufficient for advanced forms of human-machine interface. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Plasma-surface interactions

    International Nuclear Information System (INIS)

    Goeckner, M J; Nelson, C T; Sant, S P; Jindal, A K; Joseph, E A; Zhou, B S; Padron-Wells, G; Jarvis, B; Pierce, R; Overzet, L J

    2008-01-01

    Materials processing is at a crossroads. Currently a large fraction of industrially viable materials processing is via plasmas. Until recently it has been economical to just examine the influence the plasma properties on the desired surface processes and through this ultimately optimize manufacturing. For example, it is well known that the surface processes (etch or deposition), occur in the top few mono-layers of the surface. Thus, in film growth one requires that molecules from the gas-phase land and bond on the surface. However as processing has reached the nano-scale, development of viable processes has become more and more difficult. In part, this is because of all of the free parameters that exist in plasmas. To overcome this economic issue, tool vendors and semiconductor companies have turned to complex computational models of processing plasmas. For those models to work, one requires a through understanding of all of the gas-phase and surface-phase processes that are exhibited in plasmas. Unfortunately, these processes, particularly those at the surface, are not well understood. In this article we describe a viable model of the surface-phase based on cross sections for processes that occur. While originally developed of fluorocarbon systems, the model also appears to be applicable to hydrocarbon systems.

  7. Electrokinetics on superhydrophobic surfaces

    International Nuclear Information System (INIS)

    Papadopoulos, Periklis; Deng Xu; Vollmer, Doris; Butt, Hans-Jürgen

    2012-01-01

    On a superhydrophobic surface a liquid is exposed to a large air-water interface. The reduced wall friction is expected to cause a higher electro-osmotic mobility. On the other hand, the low charge density of a superhydrophobic surface reduces the electro-osmotic mobility. Due to a lack of experimental data it has not been clear so far whether the reduced wall friction or the reduced charge density dominate the electrokinetic mobilities. To separate the relative contributions of electrophoresis and electro-osmosis, the mobilities of colloids on a negatively charged hydrophilic, a superhydrophobic (Cassie) and a partially hydrophilized superhydrophobic (Cassie composite) coating were measured. To vary the charge density as well as its sign with respect to those of the colloids the partially hydrophilized surfaces were coated with polyelectrolytes. We analyzed the electrokinetic mobilities of negatively charged polystyrene colloids dispersed in aqueous medium on porous hydrophilic and superhydrophobic surfaces by confocal laser scanning electron microscopy. In all cases, the external electric field was parallel to the surface. The total electrokinetic mobilities on the superhydrophobic (Cassie) and negatively charged partially hydrophilized (Cassie composite) surfaces were similar, showing that electro-osmosis is small compared to electrophoresis. The positively charged Cassie composite surfaces tend to ‘trap’ the colloids due to attracting electrostatic interactions and rough morphology, reducing the mobility. Thus, either the charge density of the coatings in the Cassie composite state or its slip length is too low to enhance electro-osmosis.

  8. Dynamics at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sylvia Ceyer, Nancy Ryan Gray

    2010-05-04

    The 2009 Gordon Conference on Dynamics at Surfaces is the 30th anniversary of a meeting held every two years that is attended by leading researchers in the area of experimental and theoretical dynamics at liquid and solid surfaces. The conference focuses on the dynamics of the interaction of molecules with either liquid or solid surfaces, the dynamics of the outermost layer of liquid and solid surfaces and the dynamics at the liquid-solid interface. Specific topics that are featured include state-to-state dynamics, non-adiabatic interactions in molecule-metal systems, photon induced desorption from semiconductor and metal surfaces, ultrafast x-ray and electron diffraction as probes of the dynamics of ablation, ultrafast vibrational spectroscopy of water surface dynamics, dynamics of a single adsorbate, growth at nano-scale mineral surfaces, dynamics of atom recombination on interstellar dust grains and the dynamics of the interaction of water with lipid bilayers. The conference brings together investigators from a variety of scientific disciplines including chemistry, physics, materials science, geology and biophysics.

  9. Progressive Response Surfaces

    Science.gov (United States)

    Romero, V. J.; Swiler, L. P.

    2004-01-01

    Response surface functions are often used as simple and inexpensive replacements for computationally expensive computer models that simulate the behavior of a complex system over some parameter space. Progressive response surfaces are ones that are built up progressively as global information is added from new sample points in the parameter space. As the response surfaces are globally upgraded based on new information, heuristic indications of the convergence of the response surface approximation to the exact (fitted) function can be inferred. Sampling points can be incrementally added in a structured fashion, or in an unstructured fashion. Whatever the approach, at least in early stages of sampling it is usually desirable to sample the entire parameter space uniformly. At later stages of sampling, depending on the nature of the quantity being resolved, it may be desirable to continue sampling uniformly over the entire parameter space (Progressive response surfaces), or to switch to a focusing/economizing strategy of preferentially sampling certain regions of the parameter space based on information gained in early stages of sampling (Adaptive response surfaces). Here we consider Progressive response surfaces where a balanced indication of global response over the parameter space is desired.We use a variant of Moving Least Squares to fit and interpolate structured and unstructured point sets over the parameter space. On a 2-D test problem we compare response surface accuracy for three incremental sampling methods: Progressive Lattice Sampling; Simple-Random Monte Carlo; and Halton Quasi-Monte-Carlo sequences. We are ultimately after a system for constructing efficiently upgradable response surface approximations with reliable error estimates.

  10. Surface physics : experimental

    International Nuclear Information System (INIS)

    Padalia, B.D.

    1978-01-01

    In this report, discussion is confined to some important ultra high vacuum surface techniques such as ultra-violet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and the low energy electron diffraction (LEED). An attempt is made to cover the basic principles and the experimental details of XPS and AES. Selected examples illustrating the potentialities of the above techniques to solve the important basic as well as applied problems relating to surfaces are presented. Salient features of the available commercial machines in which UPS, AES and LEED are combined to facilitate surface examination sequentially or simultaneously under identical experimental conditions are indicated. (auth.)

  11. Advanced Surface Technology

    DEFF Research Database (Denmark)

    Møller, Per; Nielsen, Lars Pleht

    , nitriding, carbonitriding, and many other lesser-known thermochemical processes used for solving technological problems. The book is richly illustrated with pictures and figures showing how the technology creates new innovative solutions for industry and how surfaces are becoming integral to the function......This new significant book on advanced modern surface technology in all its variations, is aimed at both teaching at engineering schools and practical application in industry. The work covers all the significant aspects of modern surface technology and also describes how new advanced techniques make...

  12. Surface modes in physics

    CERN Document Server

    Sernelius, Bo E

    2011-01-01

    Electromagnetic surface modes are present at all surfaces and interfaces between material of different dielectric properties. These modes have very important effects on numerous physical quantities: adhesion, capillary force, step formation and crystal growth, the Casimir effect etc. They cause surface tension and wetting and they give rise to forces which are important e.g. for the stability of colloids.This book is a useful and elegant approach to the topic, showing how the concept of electromagnetic modes can be developed as a unifying theme for a range of condensed matter physics. The

  13. Surface science techniques

    CERN Document Server

    Walls, JM

    2013-01-01

    This volume provides a comprehensive and up to the minute review of the techniques used to determine the nature and composition of surfaces. Originally published as a special issue of the Pergamon journal Vacuum, it comprises a carefully edited collection of chapters written by specialists in each of the techniques and includes coverage of the electron and ion spectroscopies, as well as the atom-imaging methods such as the atom probe field ion microscope and the scanning tunnelling microscope. Surface science is an important area of study since the outermost surface layers play a crucial role

  14. Architectural Knitted Surfaces

    DEFF Research Database (Denmark)

    Mossé, Aurélie

    2010-01-01

    WGSN reports from the Architectural Knitted Surfaces workshop recently held at ShenkarCollege of Engineering and Design, Tel Aviv, which offered a cutting-edge insight into interactive knitted surfaces. With the increasing role of smart textiles in architecture, the Architectural Knitted Surfaces...... workshop brought together architects and interior and textile designers to highlight recent developments in intelligent knitting. The five-day workshop was led by architects Ayelet Karmon and Mette Ramsgaard Thomsen, together with Amir Cang and Eyal Sheffer from the Knitting Laboratory, in collaboration...

  15. Nonlinear surface electromagnetic phenomena

    CERN Document Server

    Ponath, H-E

    1991-01-01

    In recent years the physics of electromagnetic surface phenomena has developed rapidly, evolving into technologies for communications and industry, such as fiber and integrated optics. The variety of phenomena based on electromagnetism at surfaces is rich and this book was written with the aim of summarizing the available knowledge in selected areas of the field. The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are

  16. Localized Acoustic Surface Modes

    KAUST Repository

    Farhat, Mohamed

    2015-08-04

    We introduce the concept of localized acoustic surface modes (ASMs). We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  17. Advanced Surface Technology

    DEFF Research Database (Denmark)

    Møller, Per; Nielsen, Lars Pleht

    This new significant book on advanced modern surface technology in all its variations, is aimed at both teaching at engineering schools and practical application in industry. The work covers all the significant aspects of modern surface technology and also describes how new advanced techniques make......, nitriding, carbonitriding, and many other lesser-known thermochemical processes used for solving technological problems. The book is richly illustrated with pictures and figures showing how the technology creates new innovative solutions for industry and how surfaces are becoming integral to the function...

  18. Chemical surface decontamination

    International Nuclear Information System (INIS)

    Alexa, J.

    1978-12-01

    A brief analysis of the decontamination process and some general rules of the chemical decontamination of surfaces are reported. About 30 decontamination procedures developed by UJV are presented in an annex. (author)

  19. Uruguay - Surface Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface weather observation forms for 26 stations in Uruguay. Period of record 1896-2005, with two to eight observations per day. Files created through a...

  20. Mexico - Surface Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Mexican Surface Daily Observations taken at 94 observatories located throughout Mexico, beginning in 1872 and going up through 1981. The data resided on paper...

  1. Vortices on hyperbolic surfaces

    International Nuclear Information System (INIS)

    Manton, Nicholas S; Rink, Norman A

    2010-01-01

    It is shown that Abelian Higgs vortices on a hyperbolic surface M can be constructed geometrically from holomorphic maps f: M → N, where N is also a hyperbolic surface. The fields depend on f and on the metrics of M and N. The vortex centres are the ramification points, where the derivative of f vanishes. The magnitude of the Higgs field measures the extent to which f is locally an isometry. Witten's construction of vortices on the hyperbolic plane is rederived, and new examples of vortices on compact surfaces and on hyperbolic surfaces of revolution are obtained. The interpretation of these solutions as SO(3)-invariant, self-dual SU(2) Yang-Mills fields on R 4 is also given.

  2. Surface Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Surface Weather Observation Collection consists primarily of hourly, synoptic, daily, and monthly forms submitted to the archive by the National Weather Service...

  3. Land Surface Weather Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — METAR is the international standard code format for hourly surface weather observations. The acronym roughly translates from French as Aviation Routine Weather...

  4. Iowa Bedrock Surface Elevation

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This Digital Elevation Model (DEM) of the bedrock surface elevation in Iowa was compiled using all available data, principally information from GEOSAM, supplemented...

  5. Characterisation of Functional Surfaces

    DEFF Research Database (Denmark)

    Lonardo, P.M.; De Chiffre, Leonardo; Bruzzone, A.A.

    2004-01-01

    Characterisation of surfaces is of fundamental importance to control the manufacturing process and the functional performance of the part. Many applications concern contact and tribology problems, which include friction, wear and lubrication. This paper presents the techniques and instruments for...

  6. Surface Weather Observations Monthly

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface Weather Observation 1001 Forms is a set of historical manuscript records for the period 1893-1948. The collection includes two very similar form types: Form...

  7. Computer aided surface representation

    Energy Technology Data Exchange (ETDEWEB)

    Barnhill, R.E.

    1989-02-09

    The central research problem of this project is the effective representation and display of surfaces, interpolating to given information, in three or more dimensions. In a typical problem, we wish to create a surface from some discrete information. If this information is itself on another surface, the problem is to determine a surface defined on a surface,'' which is discussed below. Often, properties of an already constructed surface are desired: such geometry processing'' is described below. The Summary of Proposed Research from our original proposal describes the aims of this research project. This Summary and the Table of Contents from the original proposal are enclosed as an Appendix to this Progress Report. The broad sweep from constructive mathematics through algorithms and computer graphics displays is utilized in the research. The wide range of activity, directed in both theory and applications, makes this project unique. Last month in the first Ardent Titan delivered in the State of Arizona came to our group, funded by the DOE and Arizona State University. Although the Titan is a commercial product, its newness requires our close collaboration with Ardent to maximize results. During the past year, four faculty members and several graduate research assistants have worked on this DOE project. The gaining of new professionals is an important aspect of this project. A listing of the students and their topics is given in the Appendix. The most significant publication during the past year is the book, Curves and Surfaces for Computer Aided Geometric Design, by Dr. Gerald Farin. This 300 page volume helps fill a considerable gap in the subject and includes many new results on Bernstein-Bezier curves and surfaces.

  8. Surface and Superconductivity

    Science.gov (United States)

    Gor'kov, L. P.

    2006-07-01

    Experiments reveal the existence of metallic bands at surfaces of metals and insulators. The bands can be doped externally. We review properties of surface superconductivity that may set up in such bands at low temperatures and various means of superconductivity defection. The fundamental difference as compared to the ordinary superconductivity in metals, besides its two-dimensionality lies in the absence of the center of space inversion. This results in mixing between the singlet and triplet channels of the Cooper pairing.

  9. The surface right

    OpenAIRE

    Del Risco Sotil, Luis Felipe

    2017-01-01

    This article addresses over the regulation of the surface right in the Peruvian Law along with its main points of contact with other important institutions in the field of real estate. The author points the evolution of this figure in the Peruvian legislation and determinates its legal nature and its characteristics, establishing its relation with the principle of real estate accession property and the implications of the transitional division that the surface generates. In other relevant asp...

  10. Electron microscopy of surfaces

    International Nuclear Information System (INIS)

    Venables, J.A.

    1981-01-01

    Electron beam techniques used to study clean surfaces and surface processes on a microscopic scale are reviewed. Recent experimental examples and possible future developments are discussed. Special emphasis is given to (i) transmission diffraction and microscopy techniques, including atomic imaging; (ii) Auger microscopy on bulk and thin film samples; (iii) secondary electron microscopy, especially low energy secondaries for work-function imaging and photoelectron imaging; and (iv) reflection electron microscopy and diffraction. (orig.)

  11. Multifunctional thin film surface

    Energy Technology Data Exchange (ETDEWEB)

    Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

    2015-10-13

    A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

  12. Automated galaxy surface photometry

    International Nuclear Information System (INIS)

    Cawson, M.G.M.; Kibblewhite, E.J.; Disney, M.J.; Phillipps, S.

    1987-01-01

    Two-dimensional surface photometry of a very large number of galaxies on a deep Schmidt plate has been obtained using the Automatic Plate Measuring System (APM). A method of photometric calibration, suitable for APM measurements, via pixel-by-pixel comparison with CCD frames of a number of the brighter galaxies is described and its advantages are discussed. The same method is used to demonstrate the consistency of measurement of the APM machine when used for surface photometry. (author)

  13. Amphoteric surface active agents

    OpenAIRE

    Eissa, A.M. F.

    1995-01-01

    2-[trimethyl ammonium, triethyl ammonium, pyridinium and 2-amino pyridinium] alkanoates, four series of surface active agents containing carbon chain C12, C14, C16 and C18carbon atoms, were prepared. Their structures were characterized by microanalysis, infrared (IR) and nuclear magnetic resonance (NMR). Surface and interfacial tension, Krafft point, wetting time, emulsification power, foaming height a...

  14. Knee Angle Estimation Algorithm for Myoelectric Control of Active Transfemoral Prostheses

    Science.gov (United States)

    Delis, Alberto López; de Carvalho, João Luiz Azevedo; Da Rocha, Adson Ferreira; de Oliveira Nascimento, Francisco Assis; Borges, Geovany Araújo

    This paper presents a bioinstrumentation system for the acquisition and pre-processing of surface electromyographic (SEMG) signals, and a knee angle estimation algorithm for control of active transfemoral leg prostheses, using methods for feature extraction and classification of myoelectric signal patterns. The presented microcontrolled bioinstrumentation system is capable of recording up to four SEMG channels, and one electrogoniometer channel. The proposed neural myoelectric controller algorithm is capable of predicting the intended knee joint angle from the measured SEMG signals. The algorithm is designed in three stages: feature extraction, using auto-regressive model and amplitude histogram; feature projection, using self organizing maps; and pattern classification, using a Levenberg-Marquardt neural network. The use of SEMG signals and additional mechanical information such as that provided by the electrogoniometer may improve precision in the control of leg prostheses. Preliminary results are presented.

  15. Mars Surface Environmental Issues

    Science.gov (United States)

    Charles, John

    2002-01-01

    Planetary exploration by astronauts will require extended periods of habitation on a planet's surface, under the influence of environmental factors that are different from those of Earth and the spacecraft that delivered the crew to the planet. Human exploration of Mars, a possible near-term planetary objective, can be considered a challenging scenario. Mission scenarios currently under consideration call for surface habitation periods of from 1 to 18 months on even the earliest expeditions. Methods: Environmental issues associated with Mars exploration have been investigated by NASA and the National Space Biomedical Research Institute (NSBRI) as part of the Bioastronautics Critical Path Roadmap Project (see http ://criticalpath.jsc.nasa.gov). Results: Arrival on Mars will immediately expose the crew to gravity only 38% of that at Earth's surface in possibly the first prolonged exposure to gravity other than the 1G of Earth's surface and the zero G of weightless space flight, with yet unknown effects on crew physiology. The radiation at Mars' surface is not well documented, although the planet's bulk and even its thin atmosphere may moderate the influx of galactic cosmic radiation and energetic protons from solar flares. Secondary radiation from activated components of the soil must also be considered. Ultrafine and larger respirable and nonrespirable particles in Martian dust introduced into the habitat after surface excursions may induce pulmonary inflammation exacerbated by the additive reactive and oxidizing nature of the dust. Stringent decontamination cannot eliminate mechanical and corrosive effects of the dust on pressure suits and exposed machinery. The biohazard potential of putative indigenous Martian microorganisms may be assessed by comparison with analog environments on Earth. Even in their absence, human microorganisms, if not properly controlled, can be a threat to the crew's health. Conclusions: Mars' surface offers a substantial challenge to the

  16. Glycoprotein on cell surfaces

    International Nuclear Information System (INIS)

    Muramatsu, T.

    1975-01-01

    There are conjugated polysaccharides in cell membranes and outside of animal cells, and they play important role in the control of cell behavior. In this paper, the studies on the glycoprotein on cell surfaces are reported. It was found that the glycoprotein on cell surfaces have both N-glycoside type and O-glycoside type saccharic chains. Therefore it can be concluded that the basic structure of the saccharic chains in the glycoprotein on cell surfaces is similar to that of blood serum and body fluid. The main glycoprotein in the membranes of red blood corpuscles has been studied most in detail, and it also has both types of saccharic chains. The glycoprotein in liver cell membranes was found to have only the saccharic chains of acid type and to be in different pattern from that in endoplasmic reticula and nuclear membranes, which also has the saccharic chains of neutral type. The structure of the saccharic chains of H-2 antigen, i.e. the peculiar glycoprotein on the surfaces of lymph system cells, has been studied, and it is similar to the saccharic chains of glycoprotein in blood serum. The saccharic chain structures of H-2 antigen and TL antigen are different. TL, H-2 (D), Lna and H-2 (K) are the glycoprotein on cell surfaces, and are independent molecules. The analysis of the saccharic chain patterns on cell surfaces was carried out, and it was shown that the acid type saccharic chains were similar to those of ordinary glycoprotein, because the enzyme of pneumococci hydrolyzed most of the acid type saccharic chains. The change of the saccharic chain patterns of glycoprotein on cell surfaces owing to canceration and multiplication is complex matter. (Kako, I.)

  17. Surface chemistry theory and applications

    CERN Document Server

    Bikerman, J J

    2013-01-01

    Surface Chemistry Theory and Applications focuses on liquid-gas, liquid-liquid, solid-gas, solid-liquid, and solid-solid surfaces. The book first offers information on liquid-gas surfaces, including surface tension, measurement of surface tension, rate of capillarity rise, capillary attraction, bubble pressure and pore size, and surface tension and temperature. The text then ponders on liquid-liquid and solid-gas surfaces. Discussions focus on surface energy of solids, surface roughness and cleanness, adsorption of gases and vapors, adsorption hysteresis, interfacial tension, and interfacial t

  18. Stability of surface nanobubbles

    Science.gov (United States)

    Maheshwari, Shantanu; van der Hoef, Martin; Zhang, Xuehua; Lohse, Detlef

    2015-11-01

    We have studied the stability and dissolution of surface nanobubbles on the chemical heterogenous surface by performing Molecular Dynamics (MD) simulations of binary mixture consists of Lennard-Jones (LJ) particles. Recently our group has derived the exact expression for equilibrium contact angle of surface nanobubbles as a function of oversaturation of the gas concentration in bulk liquid and the lateral length of bubble. It has been showed that the contact line pinning and the oversaturation of gas concentration in bulk liquid is crucial in the stability of surface nanobubbles. Our simulations showed that how pinning of the three-phase contact line on the chemical heterogenous surface lead to the stability of the nanobubble. We have calculated the equilibrium contact angle by varying the gas concentration in bulk liquid and the lateral length of the bubble. Our results showed that the equilibrium contact angle follows the expression derived analytically by our group. We have also studied the bubble dissolution dynamics and showed the ''stick-jump'' mechanism which was also observed experimentally in case of dissolution of nanodrops.

  19. Viscoelastic Surface Waves

    Science.gov (United States)

    Borcherdt, R. D.

    2007-12-01

    General theoretical solutions for Rayleigh- and Love-Type surface waves in viscoelastic media describe physical characteristics of the surface waves in elastic as well as anelastic media with arbitrary amounts of intrinsic absorption. In contrast to corresponding physical characteristics for Rayleigh waves in elastic media, Rayleigh- Type surface waves in anelastic media demonstrate; 1) tilt of the particle motion orbit that varies with depth, and 2) amplitude and volumetric strain distributions with superimposed sinusoidal variations that decay exponentially with depth. Each characteristic is dependent on the amount of intrinsic absorption and the chosen model of viscoelasticity. Distinguishing characteristics of anelastic Love-Type surface waves include: 1) dependencies of the wave speed and absorption coefficient on the chosen model and amount of intrinsic absorption and frequency, and 2) superimposed sinusoidal amplitude variations with an exponential decay with depth. Numerical results valid for a variety of viscoelastic models provide quantitative estimates of the physical characteristics of both types of viscoelastic surface waves appropriate for interpretations pertinent to models of earth materials ranging from low-loss in the crust to moderate- and high-loss in water-saturated soils.

  20. Iron oxide surfaces

    Science.gov (United States)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  1. From analysis to surface

    DEFF Research Database (Denmark)

    Bemman, Brian; Meredith, David

    In recent years, a significant body of research has focused on developing algorithms for computing analyses of mu- sical works automatically from encodings of these works' surfaces [3,4,7,10,11]. The quality of the output of such analysis algorithms is typically evaluated by comparing it with a “......In recent years, a significant body of research has focused on developing algorithms for computing analyses of mu- sical works automatically from encodings of these works' surfaces [3,4,7,10,11]. The quality of the output of such analysis algorithms is typically evaluated by comparing...... an effective (i.e., comput- able), correct and complete description of some aspect of the structure of the music. Generating the surface struc- ture of a piece from an analysis in this manner serves as a proof of the analysis' correctness, effectiveness and com- pleteness. We present a reductive analysis...

  2. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  3. Surface states and spectra

    International Nuclear Information System (INIS)

    Jaksic, V.; Last, Y.; California Inst. of Tech., Pasadena, CA

    2001-01-01

    Let Z + d+1 =Z d x Z + , let H 0 be the discrete Laplacian on the Hilbert space l 2 (Z + d+1 ) with a Dirichlet boundary condition, and let V be a potential supported on the boundary ∂Z + d+1 . We introduce the notions of surface states and surface spectrum of the operator H=H 0 +V and explore their properties. Our main result is that if the potential V is random and if the disorder is either large or small enough, then in dimension two H has no surface spectrum on σ(H 0 ) with probability one. To prove this result we combine Aizenman-Molchanov theory with techniques of scattering theory. (orig.)

  4. Cryogenic surface ion traps

    International Nuclear Information System (INIS)

    Niedermayr, M.

    2015-01-01

    Microfabricated surface traps are a promising architecture to realize a scalable quantum computer based on trapped ions. In principle, hundreds or thousands of surface traps can be located on a single substrate in order to provide large arrays of interacting ions. To this end, trap designs and fabrication methods are required that provide scalable, stable and reproducible ion traps. This work presents a novel surface-trap design developed for cryogenic applications. Intrinsic silicon is used as the substrate material of the traps. The well-developed microfabrication and structuring methods of silicon are utilized to create simple and reproducible traps. The traps were tested and characterized in a cryogenic setup. Ions could be trapped and their life time and motional heating were investigated. Long ion lifetimes of several hours were observed and the measured heating rates were reproducibly low at around 1 phonon per second at a trap frequency of 1 MHz. (author) [de

  5. Analytical caustic surfaces

    Science.gov (United States)

    Schmidt, R. F.

    1987-01-01

    This document discusses the determination of caustic surfaces in terms of rays, reflectors, and wavefronts. Analytical caustics are obtained as a family of lines, a set of points, and several types of equations for geometries encountered in optics and microwave applications. Standard methods of differential geometry are applied under different approaches: directly to reflector surfaces, and alternatively, to wavefronts, to obtain analytical caustics of two sheets or branches. Gauss/Seidel aberrations are introduced into the wavefront approach, forcing the retention of all three coefficients of both the first- and the second-fundamental forms of differential geometry. An existing method for obtaining caustic surfaces through exploitation of the singularities in flux density is examined, and several constant-intensity contour maps are developed using only the intrinsic Gaussian, mean, and normal curvatures of the reflector. Numerous references are provided for extending the material of the present document to the morphologies of caustics and their associated diffraction patterns.

  6. Changes on Titan's surface

    Science.gov (United States)

    Solomonidou, A.; Lopes, R. M. C.; Coustenis, A.; Malaska, M. J.; Sotin, C.; Rodriguez, S.; Janssen, M. A.; Drossart, P.; Lawrence, K. J.; Matsoukas, C. K.; Hirtzig, M.; Le Mouelic, S.; Jaumann, R.; Brown, R. H.; Bratsolis, E.

    2015-12-01

    Cassini's Visual and Infrared Mapping Spectrometer (VIMS) and the Titan Radar Mapper have investigated Titan's surface since 2004, unveiling a complex, dynamic and Earth-like surface. Understanding the distribution and interplay of geologic processes is important for constraining models of its interior, surface-atmospheric interactions, and climate evolution. We focus on understanding the origin of the major geomorphological units identified by Lopes et al. (2010, 2015) [1,2], Malaska et al. (2015) [3] and regions we studied in Solomonidou et al. (2014; 2015) [4,5]. Here, we investigate the nature of: Undifferentiated Plains, Hummocky/Mountainous terrains, candidate cryovolcanic sites, Labyrinth, and Dunes in terms of surface albedo behavior and spectral evolution with time to identify possible changes. Using a radiative transfer code, we find that temporal variations of surface albedo occur for some areas. Tui Regio and Sotra Patera, both candidate cryovolcanic regions, change with time, becoming darker and brighter respectively in surface albedo. In contrast, we find that the Undifferentiated Plains and the suggested evaporitic areas [6] in the equatorial regions do not present any significant changes. We are able to report the differences and similarities among the various regions and provide constraints on their chemical composition and specific processes of origin. Our results support the hypothesis that both endogenic and exogenic processes have played important roles in shaping Titan's geologic evolution. Such a variety of geologic processes and their relationship to the methane cycle make Titan important for astrobiology and habitability studies and particularly significant in solar system studies. [1] Lopes, R.M.C., et al.: Icarus, 205, 540-588, 2010; [2] Lopes, R.M.C., et al.: JGR, 118, 416-435, 2013; [3] Malaska, M., et al : Icarus, submitted, 2015;[4] Solomonidou et al.: JGR, 119, 1729-1747, 2014; [5] Solomonidou, A., et al.: In press, 2015; [6] Barnes

  7. Surface modification of bioceramics

    Science.gov (United States)

    Monkawa, Akira

    Hydroxyapatite [Ca10(PO4)6(OH)2, HAp] is a major inorganic component of bone and teeth tissues and has the excellent biocompatibility and high osteoconductivity. The interactions between HAp and protein or cell have been studied. The HAp related bioceramics such as bone substitute, coating substance of metal implants, inorganic-polymer composites, and cell culture. We described two methods; (1) surface modification of HAp using organosilane; (2) fabrication of HAp ultra-thin layer on gold surface for protein adsorption analyzed with QCM-D technique. The interfacial interaction between collagen and HAp in a nano-region was controlled by depositing the organosilane of n-octadecyltrimethoxysilane (ODS: -CH3) or aminopropyltriethoxysilane (APTS: -NH2) with a chemical vapor deposition method. The morphologies of collagen adsorbed on the surfaces of HAp and HAp deposited with APTS were similar, however that of the surface with ODS was apparently different, due to the hydrophobic interaction between the organic head group of -CH3 and residual groups of collagen. We present a method for coating gold quartz crystal microbalance with dissipation (QCM-D) sensor with ultra-thin layer of hydroxyapatite nanocrystals evenly covering and tightly bound to the surface. The hydroxyapatite sensor operated in liquid with high stability and sensitivity. The in-situ adsorption mechanism and conformational change of fibrinogen on gold, titanium and hydroxyapatite surfaces were investigated by QCM-D technique and Fourier-transform infrared spectroscopy. The study indicates that the hydroxyapatite sensor is applicable for qualitative and conformational analysis of protein adsorption.

  8. Organometallic chemistry of metal surfaces

    International Nuclear Information System (INIS)

    Muetterties, E.L.

    1981-06-01

    The organometallic chemistry of metal surfaces is defined as a function of surface crystallography and of surface composition for a set of cyclic hydrocarbons that include benzene, toluene, cyclohexadienes, cyclohexene, cyclohexane, cyclooctatetraene, cyclooctadienes, cyclooctadiene, cycloheptatriene and cyclobutane. 12 figures

  9. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    application is modulation of optical waves in waveguides. This presentation elaborates on how a SAW is generated by interdigital transducers using a 2D model of a piezoelectric, inhomogeneous material implemented in the high-level programming language Comsol Multiphysics. The SAW is send through a model......The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...

  10. Solid lubricants and surfaces

    CERN Document Server

    Braithwaite, E R

    1964-01-01

    Solid Lubricants and Surfaces deals with the theory and use of solid lubricants, particularly in colloidal form. Portions of this book are devoted to graphite and molybdenum disulfides, which are widely used solid lubricants in colloidal form. An extensive literature on the laboratory examination of hundreds of solids as potential lubricants is also provided in this text. Other topics discussed include the metals and solid lubricants; techniques for examining surfaces; other solid lubricants; metal shaping; and industrial uses of solid-lubricant dispersions. This publication is beneficial to e

  11. Photochemistry on solid surfaces

    CERN Document Server

    Matsuura, T

    1989-01-01

    The latest developments in photochemistry on solid surfaces, i.e. photochemistry in heterogeneous systems, including liquid crystallines, are brought together for the first time in a single volume. Distinguished photochemists from various fields have contributed to the book which covers a number of important applications: molecular photo-devices for super-memory, photochemical vapor deposition to produce thin-layered electronic semiconducting materials, sensitive optical media, the control of photochemical reactions pathways, etc. Photochemistry on solid surfaces is now a major field and this

  12. Quantitative Hydrocarbon Surface Analysis

    Science.gov (United States)

    Douglas, Vonnie M.

    2000-01-01

    The elimination of ozone depleting substances, such as carbon tetrachloride, has resulted in the use of new analytical techniques for cleanliness verification and contamination sampling. The last remaining application at Rocketdyne which required a replacement technique was the quantitative analysis of hydrocarbons by infrared spectrometry. This application, which previously utilized carbon tetrachloride, was successfully modified using the SOC-400, a compact portable FTIR manufactured by Surface Optics Corporation. This instrument can quantitatively measure and identify hydrocarbons from solvent flush of hardware as well as directly analyze the surface of metallic components without the use of ozone depleting chemicals. Several sampling accessories are utilized to perform analysis for various applications.

  13. Surface science techniques

    CERN Document Server

    Bracco, Gianangelo

    2013-01-01

    The book describes the experimental techniques employed to study surfaces and interfaces. The emphasis is on the experimental method. Therefore all chapters start with an introduction of the scientific problem, the theory necessary to understand how the technique works and how to understand the results. Descriptions of real experimental setups, experimental results at different systems are given to show both the strength and the limits of the technique. In a final part the new developments and possible extensions of the techniques are presented. The included techniques provide microscopic as well as macroscopic information. They cover most of the techniques used in surface science.

  14. Surface and nanomolecular catalysis

    CERN Document Server

    Richards, Ryan

    2006-01-01

    Using new instrumentation and experimental techniques that allow scientists to observe chemical reactions and molecular properties at the nanoscale, the authors of Surface and Nanomolecular Catalysis reveal new insights into the surface chemistry of catalysts and the reaction mechanisms that actually occur at a molecular level during catalysis. While each chapter contains the necessary background and explanations to stand alone, the diverse collection of chapters shows how developments from various fields each contributed to our current understanding of nanomolecular catalysis as a whole. The

  15. Solar Surface Convection

    Directory of Open Access Journals (Sweden)

    Nordlund Åke

    2009-04-01

    Full Text Available We review the properties of solar convection that are directly observable at the solar surface, and discuss the relevant underlying physics, concentrating mostly on a range of depths from the temperature minimum down to about 20 Mm below the visible solar surface.The properties of convection at the main energy carrying (granular scales are tightly constrained by observations, in particular by the detailed shapes of photospheric spectral lines and the topology (time- and length-scales, flow velocities, etc. of the up- and downflows. Current supercomputer models match these constraints very closely, which lends credence to the models, and allows robust conclusions to be drawn from analysis of the model properties.At larger scales the properties of the convective velocity field at the solar surface are strongly influenced by constraints from mass conservation, with amplitudes of larger scale horizontal motions decreasing roughly in inverse proportion to the scale of the motion. To a large extent, the apparent presence of distinct (meso- and supergranulation scales is a result of the folding of this spectrum with the effective “filters” corresponding to various observational techniques. Convective motions on successively larger scales advect patterns created by convection on smaller scales; this includes patterns of magnetic field, which thus have an approximately self-similar structure at scales larger than granulation.Radiative-hydrodynamical simulations of solar surface convection can be used as 2D/3D time-dependent models of the solar atmosphere to predict the emergent spectrum. In general, the resulting detailed spectral line profiles agree spectacularly well with observations without invoking any micro- and macroturbulence parameters due to the presence of convective velocities and atmosphere inhomogeneities. One of the most noteworthy results has been a significant reduction in recent years in the derived solar C, N, and O abundances with

  16. Dyakonov surface waves

    DEFF Research Database (Denmark)

    Takayama, Osamu; Crasovan, Lucian Cornel; Johansen, Steffen Kjær

    2008-01-01

    The interface of two semi-infinite media, where at least one of them is a birefringent crystal, supports a special type of surface wave that was predicted theoretically by D'yakonov in 1988. Since then, the properties of such waves, which exist in transparent media only under very special...... conditions, have been analyzed in different geometries and settings. Nevertheless, they are still awaiting experimental demonstration. The most important advances in this topic are briefly discussed in this review, pointing out aspects that have not been clearly covered by the literature. Finally......, the existence of these surface waves in specific material examples is analyzed, discussing the challenge posed by their experimental observation....

  17. Surfing surface gravity waves

    Science.gov (United States)

    Pizzo, Nick

    2017-11-01

    A simple criterion for water particles to surf an underlying surface gravity wave is presented. It is found that particles travelling near the phase speed of the wave, in a geometrically confined region on the forward face of the crest, increase in speed. The criterion is derived using the equation of John (Commun. Pure Appl. Maths, vol. 6, 1953, pp. 497-503) for the motion of a zero-stress free surface under the action of gravity. As an example, a breaking water wave is theoretically and numerically examined. Implications for upper-ocean processes, for both shallow- and deep-water waves, are discussed.

  18. Hyperpolarized Nanodiamond Surfaces.

    Science.gov (United States)

    Rej, Ewa; Gaebel, Torsten; Waddington, David E J; Reilly, David J

    2017-01-11

    The widespread use of nanodiamond as a biomedical platform for drug-delivery, imaging, and subcellular tracking applications stems from its nontoxicity and unique quantum mechanical properties. Here, we extend this functionality to the domain of magnetic resonance, by demonstrating that the intrinsic electron spins on the nanodiamond surface can be used to hyperpolarize adsorbed liquid compounds at low fields and room temperature. By combining relaxation measurements with hyperpolarization, spins on the surface of the nanodiamond can be distinguished from those in the bulk liquid. These results are likely of use in signaling the controlled release of pharmaceutical payloads.

  19. Friction Surfacing In Steel 304

    OpenAIRE

    S. Godwin Barnabas; Anantharam; Shyam sundar; B.S.Aravind T.Prabhu

    2016-01-01

    Surface engineering deals with the surface of the solid matter and it is sub-discipline of The surface phase of a solid interacts with the surrounding environment. This interaction can degrade the surface phase over time, may result in loss of material from its surface. Environmental degradation of the surface phase over time can be caused by wear, corrosion, creep, fatigue loads, shear loads, tensile loads, cutting forces or when exposed to higher temperature. Wear can be minimiz...

  20. Surface segregation during irradiation

    International Nuclear Information System (INIS)

    Rehn, L.E.; Lam, N.Q.

    1985-10-01

    Gibbsian adsorption is known to alter the surface composition of many alloys. During irradiation, four additional processes that affect the near-surface alloy composition become operative: preferential sputtering, displacement mixing, radiation-enhanced diffusion and radiation-induced segregation. Because of the mutual competition of these five processes, near-surface compositional changes in an irradiation environment can be extremely complex. Although ion-beam induced surface compositional changes were noted as long as fifty years ago, it is only during the past several years that individual mechanisms have been clearly identified. In this paper, a simple physical description of each of the processes is given, and selected examples of recent important progress are discussed. With the notable exception of preferential sputtering, it is shown that a reasonable qualitative understanding of the relative contributions from the individual processes under various irradiation conditions has been attained. However, considerably more effort will be required before a quantitative, predictive capability can be achieved. 29 refs., 8 figs

  1. Predictive Surface Complexation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sverjensky, Dimitri A. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Earth and Planetary Sciences

    2016-11-29

    Surface complexation plays an important role in the equilibria and kinetics of processes controlling the compositions of soilwaters and groundwaters, the fate of contaminants in groundwaters, and the subsurface storage of CO2 and nuclear waste. Over the last several decades, many dozens of individual experimental studies have addressed aspects of surface complexation that have contributed to an increased understanding of its role in natural systems. However, there has been no previous attempt to develop a model of surface complexation that can be used to link all the experimental studies in order to place them on a predictive basis. Overall, my research has successfully integrated the results of the work of many experimentalists published over several decades. For the first time in studies of the geochemistry of the mineral-water interface, a practical predictive capability for modeling has become available. The predictive correlations developed in my research now enable extrapolations of experimental studies to provide estimates of surface chemistry for systems not yet studied experimentally and for natural and anthropogenically perturbed systems.

  2. Real Compact Surfaces

    Indian Academy of Sciences (India)

    The classification of real compact surfaces is a main result which is at the same time easy to understand and non- trivial, simple in formulation and rich in consequences. The aim of this article is to explain the theorem by means of many drawings. It is an invitation to a visual approach of mathematics. First Definitions and ...

  3. Optimization of surface maintenance

    International Nuclear Information System (INIS)

    Oeverland, E.

    1990-01-01

    The present conference paper deals with methods of optimizing the surface maintenance of steel-made offshore installations. The paper aims at identifying important approaches to the problems regarding the long-range planning of an economical and cost effective maintenance program. The methods of optimization are based on the obtained experiences from the maintenance of installations on the Norwegian continental shelf. 3 figs

  4. Scraped surface heat exchangers.

    Science.gov (United States)

    Rao, Chetan S; Hartel, Richard W

    2006-01-01

    Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. They are ideally suited for products that are viscous, sticky, that contain particulate matter, or that need some degree of crystallization. Since these characteristics describe a vast majority of processed foods, SSHEs are especially suited for pumpable food products. During operation, the product is brought in contact with a heat transfer surface that is rapidly and continuously scraped, thereby exposing the surface to the passage of untreated product. In addition to maintaining high and uniform heat exchange, the scraper blades also provide simultaneous mixing and agitation. Heat exchange for sticky and viscous foods such as heavy salad dressings, margarine, chocolate, peanut butter, fondant, ice cream, and shortenings is possible only by using SSHEs. High heat transfer coefficients are achieved because the boundary layer is continuously replaced by fresh material. Moreover, the product is in contact with the heating surface for only a few seconds and high temperature gradients can be used without the danger of causing undesirable reactions. SSHEs are versatile in the use of heat transfer medium and the various unit operations that can be carried out simultaneously. This article critically reviews the current understanding of the operations and applications of SSHEs.

  5. Surface Nanobubbles Nucleate Microdroplets

    NARCIS (Netherlands)

    Zhang, Xuehua; Lhuissier, H.E.; Sun, Chao; Lohse, Detlef

    2014-01-01

    When a hydrophobic solid is in contact with water, surface nanobubbles often form at the interface. They have a lifetime many orders of magnitude longer than expected. Here, we show that they even withstand a temperature increase to temperatures close to the boiling point of bulk water; i.e., they

  6. Biofunctional surface engineering

    CERN Document Server

    Scholz, Martin

    2014-01-01

    PrefaceRegulatory issuesSterilization of combination devicesPolyelectrolyte monolayers (I)Polyelectrolyte monolayers (II)Surface modificationsThree dimensional characterization of immobilized biomolecules Aptamers for biofunctionalization of stentsCoating of implants with antibioticsMicroneedles and nanopatchesfor vaccinationMicrochips for antibody binding analysesBiofunctionalized wound dressingsExtracorporeal device for trapping circulating tumor cellsOutlook

  7. Surface Radiation Budget

    Science.gov (United States)

    Stackhouse, Paul W. (Principal Investigator)

    The Surface Radiation Budget (SRB) data sets contain global 3-hourly, daily and monthly averages of surface longwave and shortwave radiative properties, cloud amount, and meteorological properties computed using models. The main input data for these models include cloud information, top-of-atmosphere radiances and profiles of atmospheric water vapor and temperature. Some of the input data include Earth Radiation Budget Energy (ERBE) top-of-atmosphere clear-sky albedo and International Satellite Cloud Climatology Project (ISCCP) radiances and cloud amount. SRB parameters derived for the renewable energy community are also available from the Surface meteorology and Solar Energy (SSE) data set. Other SRB data are available from Clouds and the Earth's Radiant Energy System (CERES) and Multi-angle Imaging SpectroRadiometer (MISR). [Mission Objectives] The objective of the SRB Project is to produce and archive a global data set of shortwave (SW) and longwave (LW) surface and top of the atmosphere parameters. The data generated in the SRB project may be used in conjunction with other data sets to facilitate the development of renewable energy resources and increase understanding of radiative properties within the meteorological community. [Temporal_Coverage: Start_Date=1983-07-01; Stop_Date=2005-06-30] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180].

  8. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael

    2010-07-26

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, socalled panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects. © 2010 ACM.

  9. Tritium-surface interactions

    International Nuclear Information System (INIS)

    Kirkaldy, J.S.

    1983-06-01

    The report deals broadly with tritium-surface interactions as they relate to a fusion power reactor enterprise, viz., the vacuum chamber, first wall, peripherals, pumping, fuel recycling, isotope separation, repair and maintenance, decontamination and safety. The main emphasis is on plasma-surface interactions and the selection of materials for fusion chamber duty. A comprehensive review of the international (particularly U.S.) research and development is presented based upon a literature review (about 1 000 reports and papers) and upon visits to key laboratories, Sandia, Albuquerque, Sandia, Livermore and EGβG Idaho. An inventory of Canadian expertise and facilities for RβD on tritium-surface interactions is also presented. A number of proposals are made for the direction of an optimal Canadian RβD program, emphasizing the importance of building on strength in both the technological and fundamental areas. A compendium of specific projects and project areas is presented dealing primarily with plasma-wall interactions and permeation, anti-permeation materials and surfaces and health, safety and environmental considerations. Potential areas of industrial spinoff are identified

  10. Laser surface cleaning

    International Nuclear Information System (INIS)

    Freiwald, J.G.; Freiwald, D.A.

    1994-01-01

    The objective of this work is a laboratory demonstration that red-lead primer and two-part epoxy paints can be stripped from concrete and metal surfaces using surface cleaning systems based on pulsed-repetition CO 2 lasers. The three goals are to: (1) demonstrate coatings removal, including surface pore cleaning; (2) demonstrate that there is negligible release of ablated contaminants to the environment; and (3) demonstrate that the process will generate negligible amounts of additional waste compared to competing technologies. Phase 1 involved site visits to RMI and Fernald to assess the cleaning issues for buildings and parts. In addition, Phase 1 included detailed designs of a more powerful system for industrial cleaning rates, including laser, articulating optics, ablated-material capture suction nozzle attached to a horizontal raster scanner for floor cleaning, and filtration system. Some concept development is also being done for using robots, and for parts cleaning. In Phase 2 a transportable 6 kW system will be built and tested, with a horizontal surface scanner for cleaning paint from floors. The laboratory tests will again be instrumented. Some concept development will continue for using robots, and for parts cleaning. This report describes Phase 1 results

  11. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael

    2010-07-25

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, so-called panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects.

  12. Wetting of real surfaces

    CERN Document Server

    Bormashenko, Edward Yu

    2013-01-01

    The problem of wetting and drop dynamics on various surfaces is very interesting from both the scientificas well as thepractical viewpoint, and subject of intense research.The results are scattered across papers in journals, sothis workwill meet the need for a unifying, comprehensive work.

  13. Surface Water in Hawaii

    Science.gov (United States)

    Oki, Delwyn S.

    2003-01-01

    Surface water in Hawaii is a valued resource as well as a potential threat to human lives and property. The surface-water resources of Hawaii are of significant economic, ecologic, cultural, and aesthetic importance. Streams supply more than 50 percent of the irrigation water in Hawaii, and although streams supply only a few percent of the drinking water statewide, surface water is the main source of drinking water in some places. Streams also are a source of hydroelectric power, provide important riparian and instream habitats for many unique native species, support traditional and customary Hawaiian gathering rights and the practice of taro cultivation, and possess valued aesthetic qualities. Streams affect the physical, chemical, and aesthetic quality of receiving waters, such as estuaries, bays, and nearshore waters, which are critical to the tourism-based economy of the islands. Streams in Hawaii pose a danger because of their flashy nature; a stream's stage, or water level, can rise several feet in less than an hour during periods of intense rainfall. Streams in Hawaii are flashy because rainfall is intense, drainage basins are small, basins and streams are steep, and channel storage is limited. Streamflow generated during periods of heavy rainfall has led to loss of property and human lives in Hawaii. Most Hawaiian streams originate in the mountainous interiors of the islands and terminate at the coast. Streams are significant sculptors of the Hawaiian landscape because of the erosive power of the water they convey. In geologically young areas, such as much of the southern part of the island of Hawaii, well-defined stream channels have not developed because the permeability of the surface rocks generally is so high that rainfall infiltrates before flowing for significant distances on the surface. In geologically older areas that have received significant rainfall, streams and mass wasting have carved out large valleys.

  14. Multiscale feature based analysis of surface EMG signals under fatigue and non-fatigue conditions.

    Science.gov (United States)

    Navaneethakrishna, M; Ramakrishnan, S

    2014-01-01

    In this work, an attempt has been made to differentiate sEMG signals under muscle fatigue and non-fatigue conditions using multiscale features. Signals are recorded from biceps brachii muscle of 50 normal adults during repetitive dynamic contractions. After prescribed preprocessing, each signal is divided into six segments out of which first and last segments are considered in this analysis. Multiscale RMS (MSRMS) and Multiscale Permutation Entropy (MSPE) are computed for each subject in the time scales ranging from 1 to 50. The median values of the MSRMS and MSPE are calculated for further analysis. The results show an increase in amplitude for sEMG signals under fatigue condition. MSRMS values are found to be significantly higher in fatigue. An approximately constant difference in MSRMS value between fatigue and non-fatigue condition is observed over the entire time scale with a negative slope. Further, the median of MSRMS values for each subject is able to distinguish fatigue and non-fatigue conditions. Similar analysis on MSPE showed significant difference between fatigue and non-fatigue cases and lower values of MSPE is observed in fatigue. It is also observed that the median value of MSRMS and MSPE are able to distinguish these conditions. t-test for MSRMS, MSPE and their median value show high statistical significance. It appears that this method of analysis can be used for clinical evaluation of muscles.

  15. Statistical mechanics of random surfaces

    International Nuclear Information System (INIS)

    Froehlich, J.

    1984-01-01

    The statistical mechanics of random surfaces has proven to be of growing importance in quantum field theory (string theory, random surface representations of gauge theory) and condensed matter physics (domain walls and interfaces, incommensurate phases, spin glasses, crystal surfaces, surface phenomena such as wetting, etc.). Various applications to quantum field theory and condensed matter physics are outlined. (Auth.)

  16. Drop Impact on Superheated Surfaces

    NARCIS (Netherlands)

    Tran, Tuan; Staat, Erik-Jan; Prosperetti, Andrea; Sun, Chao; Lohse, Detlef

    2012-01-01

    At the impact of a liquid droplet on a smooth surface heated above the liquid’s boiling point, the droplet either immediately boils when it contacts the surface (“contact boiling”), or without any surface contact forms a Leidenfrost vapor layer towards the hot surface and bounces back (“gentle film

  17. Surface decontamination compositions and methods

    Science.gov (United States)

    Wright,; Karen, E [Idaho Falls, ID; Cooper, David C [Idaho Falls, ID; Peterman, Dean R [Idaho Falls, ID; Demmer, Ricky L [Idaho Falls, ID; Tripp, Julia L [Pocatello, ID; Hull, Laurence C [Idaho Falls, ID

    2011-03-29

    Clay-based compositions capable of absorbing contaminants from surfaces or objects having surface faces may be applied to a surface and later removed, the removed clay-based compositions absorbing at least a portion of the contaminant from the surface or object to which it was applied.

  18. Do whole body vibration exercises affect lower limbs neuromuscular activity in populations with a medical condition? A systematic review.

    Science.gov (United States)

    Dionello, Carla Fontoura; de Souza, Patrícia Lopes; Sá-Caputo, Danubia; Morel, Danielle Soares; Moreira-Marconi, Eloá; Paineiras-Domingos, Laisa Liane; Frederico, Eric Heleno Freire Ferreira; Guedes-Aguiar, Eliane; Paiva, Patricia de Castro; Taiar, Redha; Chiementin, Xavier; Marín, Pedro J; Bernardo-Filho, Mario

    2017-01-01

    The use of surface electromyography (sEMG) to evaluate muscle activation when executing whole body vibration exercises (WBVE) in studies provide neuromuscular findings, in healthy and diseased populations. Perform a systematic review of the effects of WBVE by sEMG of lower limbs in non-healthy populations. The search using the defined keywords was performed in PubMed, PEDRo and EMBASE databases by three independent researchers. Applying the PRISMA statement several studies were selected according to eligibility criteria and organized for the review. Full papers were included if they described effects of WBVE for the treatment of illnesses, evaluated by sEMG of lower limbs independently on the year of the publication; in comparison or associated with other treatment and evaluation techniques. Seven publications were selected; two in spinal cord injury patients, one in Friedreich's ataxia patients, three in stroke patients and one study in breast cancer survivors. Reported effects of WBV in were muscle activation by sEMG and also on strength, blood flow and exercise resistance; even in paretic limbs. By the use of sEMG it was verified that WBVE elicits muscle activation in diseased population. These results may lead to the definition of exercise protocols to maintain or increase muscular activation. However, due to the heterogeneity of methods among studies, there is currently no consensus on the sEMG signal processing. These strategies might also induce effects on muscle strength, balance and flexibility in these and other illnesses.

  19. Antibacterial Metallic Touch Surfaces

    Directory of Open Access Journals (Sweden)

    Victor M. Villapún

    2016-08-01

    Full Text Available Our aim is to present a comprehensive review of the development of modern antibacterial metallic materials as touch surfaces in healthcare settings. Initially we compare Japanese, European and US standards for the assessment of antimicrobial activity. The variations in methodologies defined in these standards are highlighted. Our review will also cover the most relevant factors that define the antimicrobial performance of metals, namely, the effect of humidity, material geometry, chemistry, physical properties and oxidation of the material. The state of the art in contact-killing materials will be described. Finally, the effect of cleaning products, including disinfectants, on the antimicrobial performance, either by direct contact or by altering the touch surface chemistry on which the microbes attach, will be discussed. We offer our outlook, identifying research areas that require further development and an overview of potential future directions of this exciting field.

  20. Discrete Minimal Surface Algebras

    Directory of Open Access Journals (Sweden)

    Joakim Arnlind

    2010-05-01

    Full Text Available We consider discrete minimal surface algebras (DMSA as generalized noncommutative analogues of minimal surfaces in higher dimensional spheres. These algebras appear naturally in membrane theory, where sequences of their representations are used as a regularization. After showing that the defining relations of the algebra are consistent, and that one can compute a basis of the enveloping algebra, we give several explicit examples of DMSAs in terms of subsets of sl_n (any semi-simple Lie algebra providing a trivial example by itself. A special class of DMSAs are Yang-Mills algebras. The representation graph is introduced to study representations of DMSAs of dimension d ≤ 4, and properties of representations are related to properties of graphs. The representation graph of a tensor product is (generically the Cartesian product of the corresponding graphs. We provide explicit examples of irreducible representations and, for coinciding eigenvalues, classify all the unitary representations of the corresponding algebras.

  1. Deformations of surface singularities

    CERN Document Server

    Szilárd, ágnes

    2013-01-01

    The present publication contains a special collection of research and review articles on deformations of surface singularities, that put together serve as an introductory survey of results and methods of the theory, as well as open problems, important examples and connections to other areas of mathematics. The aim is to collect material that will help mathematicians already working or wishing to work in this area to deepen their insight and eliminate the technical barriers in this learning process. This also is supported by review articles providing some global picture and an abundance of examples. Additionally, we introduce some material which emphasizes the newly found relationship with the theory of Stein fillings and symplectic geometry.  This links two main theories of mathematics: low dimensional topology and algebraic geometry. The theory of normal surface singularities is a distinguished part of analytic or algebraic geometry with several important results, its own technical machinery, and several op...

  2. Parsimonious Surface Wave Interferometry

    KAUST Repository

    Li, Jing

    2017-10-24

    To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.

  3. Surface control of flexoelectricity

    Science.gov (United States)

    Stengel, Massimiliano

    2014-11-01

    The polarization response of a material to a strain gradient, known as flexoelectricity, holds great promise for novel electromechanical applications. Despite considerable recent progress, however, the effect remains poorly understood. From both the fundamental and practical viewpoints, it is of crucial importance to know whether the coupling coefficients are primarily governed by the properties of the bulk material or by the details of the sample surface. Here we provide, by means of first-principles calculations, quantitative evidence supporting the latter scenario. In particular, we demonstrate that a SrTiO3 film can yield a positive or negative voltage upon bending, depending on whether it is terminated by a TiO2 or SrO layer. This result points to a full control of the flexoelectric effect via surface/interface engineering, opening exciting new avenues for device design.

  4. Surface Plasmon Singularities

    Directory of Open Access Journals (Sweden)

    Gabriel Martínez-Niconoff

    2012-01-01

    Full Text Available With the purpose to compare the physical features of the electromagnetic field, we describe the synthesis of optical singularities propagating in the free space and on a metal surface. In both cases the electromagnetic field has a slit-shaped curve as a boundary condition, and the singularities correspond to a shock wave that is a consequence of the curvature of the slit curve. As prototypes, we generate singularities that correspond to fold and cusped regions. We show that singularities in free space may generate bifurcation effects while plasmon fields do not generate these kinds of effects. Experimental results for free-space propagation are presented and for surface plasmon fields, computer simulations are shown.

  5. Surface Plasmon Nanophotonics

    CERN Document Server

    Brongersma, Mark L

    2007-01-01

    The development of advanced dielectric photonic structures has enabled tremendous control over the propagation and manipulation of light. Structures such as waveguides, splitters, mixers, and resonators now play a central role in the telecommunications industry. This book will discuss an exciting new class of photonic devices, known as surface plasmon nanophotonic structures. Surface plasmons are easily accessible excitations in metals and semiconductors and involve a collective motion of the conduction electrons. These excitations can be exploited to manipulate electromagnetic waves at optical frequencies ("light") in new ways that are unthinkable in conventional dielectric structures. The field of plasmon nanophotonics is rapidly developing and impacting a wide range of areas including: electronics, photonics, chemistry, biology, and medicine. The book will highlight several exciting new discoveries that have been made, while providing a clear discussion of the underlying physics, the nanofabrication issues...

  6. Focal surfaces of hyperbolic cylinders

    Science.gov (United States)

    Georgiev, Georgi Hristov; Pavlov, Milen Dimov

    2017-12-01

    Cylindrical surfaces have many applications in geometric modeling, architecture and other branches of engineering. In this paper, we describe two cylindrical surfaces associated to a given hyperbolic cylinder. The first one is a focal surface which is determined by reciprocal principle curvature of the hyperbolic cylinder. The second one is a generalized focal surface obtained by reciprocal mean curvature of the same hyperbolic cylinder. In particular, we show that each of these surfaces admits three different parametric representations. As consequence, it is proved that the focal and generalized focal surfaces of the hyperbolic cylinder are rational surfaces. An illustrative example is included.

  7. Surface Nanobubbles Nucleate Microdroplets

    OpenAIRE

    Zhang , Xuehua; Lhuissier , Henri; Sun , Chao; Lohse , Detlef

    2014-01-01

    International audience; When a hydrophobic solid is in contact with water, surface nanobubbles often form at the interface. They have a lifetime many orders of magnitude longer than expected. Here, we show that they even withstand a temperature increase to temperatures close to the boiling point of bulk water; i.e., they do not nucleate larger bubbles (" superstability "). On the contrary, when the vapor-liquid contact line passes a nanobubble, a liquid film remains around it, which, after pi...

  8. Surface plasmon enhanced LED

    OpenAIRE

    Vučković, Jelena; Lončar, Marko; Painter, Oskar; Scherer, Axel

    2000-01-01

    Summary form only given. We designed and fabricated an LED based on a thin semiconductor membrane (λ/2) with silver mirrors. A large spontaneous emission enhancement and a high modulation speed are obtainable due to the strong localization of the electromagnetic field in the microcavity. The coupling to surface plasmon modes which are subsequently scattered out by means of a grating is used to improve the extraction efficiency of the LED. The bottom mirror is thick and unpatterned. The top mi...

  9. Music Mixing Surface

    DEFF Research Database (Denmark)

    Gelineck, Steven; Büchert, Morten; Andersen, Jesper

    2013-01-01

    This paper presents a multi-touch based interface for mixing music. The goal of the interface is to provide users with a more intuitive control of the music mix by implementing the so-called stage metaphor control scheme, which is especially suitable for multi-touch surfaces. Specifically, we...... discuss functionality important for the professional music technician (main target user) - functionality, which is especially challenging to integrate when implementing the stage metaphor. Finally we propose and evaluate solutions to these challenges....

  10. Surface control of flexoelectricity

    OpenAIRE

    Stengel, Massimiliano

    2014-01-01

    The polarization response of a material to a strain gradient, known as flexoelectricity, holds great promise for novel electromechanical applications. Despite considerable recent progress, however, the effect remains poorly understood. From both the fundamental and practical viewpoints, it is of crucial importance to know whether the coupling coefficients are primarily governed by the properties of the bulk material or by the details of the sample surface. Here we provide, by means of first-p...

  11. Spacecraft Surface Charging Handbook

    Science.gov (United States)

    1992-11-01

    discharges however produce replacement currents that can be global. The local effect of punchthrough is illustrated by a small dipole model for the...St’rap I Farda or TEK7103 Scope Power Dipole -- Line tenna To To PA HP05000 and Spectrum X-Y Analyzer Plotter Figure 61. Test setup for surface...Testing Seminar, Los Angeles, CA, p. 77-82, 19817. Levadou, F., "Proprietes Electriques Des Materiaux." Space Environment: Prevention of Risks Related

  12. Deflation of elastic surfaces

    Science.gov (United States)

    Quilliet, Catherine; Quemeneur, François; Marmottant, Philippe; Imhof, Arnout; Pépin-Donat, Brigitte; van Blaaderen, Alfons

    2010-03-01

    The deflation of elastic spherical surfaces has been numerically investigated, and show very different types of deformations according the range of elastic parameters, some of them being quantitatively explained through simple calculations. This allows to retrieve various shapes observed on hollow shells (from colloidal to centimeter scale), on lipid vesicles, or on some biological objects. The extension of this process to other geometries allows to modelize vegetal objects such as the ultrafast trap of carnivorous plants.

  13. High surface area calcite

    Science.gov (United States)

    Schultz, L. N.; Andersson, M. P.; Dalby, K. N.; Müter, D.; Okhrimenko, D. V.; Fordsmand, H.; Stipp, S. L. S.

    2013-05-01

    Calcite (CaCO3) is important in many fields—in nature, because it is a component of aquifers, oil reservoirs and prospective CO2 storage sites, and in industry, where it is used in products as diverse as paper, toothpaste, paint, plastic and aspirin. It is difficult to obtain high purity calcite with a high surface area but such material is necessary for industrial applications and for fundamental calcite research. Commercial powder is nearly always contaminated with growth inhibitors such as sugars, citrate or pectin and most laboratory synthesis methods deliver large precipitates, often containing vaterite or aragonite. To address this problem, we (i) adapted the method of carbonating a Ca(OH)2 slurry with CO2 gas to develop the first simple, cheap, safe and reproducible procedure using common laboratory equipment, to obtain calcite that reproducibly had a surface area of 14-17 m2/g and (ii) conducted a thorough characterization of the product. Scanning electron microscopy (SEM) revealed nanometer scale, rhombohedral crystals. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) confirmed highly crystalline, pure calcite that more closely resembles the dimensions of the biogenic calcite produced by algae in coccoliths than other methods for synthesizing calcite. We suggest that this calcite is useful when purity and high surface area are important.

  14. Surface profiling interferometer

    Science.gov (United States)

    Takacs, Peter Z.; Qian, Shi-Nan

    1989-01-01

    The design of a long-trace surface profiler for the non-contact measurement of surface profile, slope error and curvature on cylindrical synchrotron radiation (SR) mirrors. The optical system is based upon the concept of a pencil-beam interferometer with an inherent large depth-of-field. The key feature of the optical system is the zero-path-difference beam splitter, which separates the laser beam into two colinear, variable-separation probe beams. A linear array detector is used to record the interference fringe in the image, and analysis of the fringe location as a function of scan position allows one to reconstruct the surface profile. The optical head is mounted on an air bearing slide with the capability to measure long aspheric optics, typical of those encountered in SR applications. A novel feature of the optical system is the use of a transverse "outrigger" beam which provides information on the relative alignment of the scan axis to the cylinder optic symmetry axis.

  15. Exotic statistics on surfaces

    International Nuclear Information System (INIS)

    Imbo, T.D.; March-Russel, J.

    1990-01-01

    We investigate the allowed spectrum of statistics for n identical spinless particles on an arbitrary closed two-manifold M, by using a powerful topological approach to the study of quantum kinematics. On a surface of genus g≥1 statistics other than Bose or Fermi can only be obtained by utilizing multi-component state vectors transforming as an irreducible unitary representation of the fundamental group of the n-particle configuration space. These multi-component (or nonscalar) quantizations allow the possibility of fractional statistics, as well as other exotic, nonfractional statistics some of whose properties we discuss. On an orientable surface of genus g≥0 only anyons with rational statistical parameter θ/π=p/q are allowed, and their number is restricted to be sq-g+1 (selement ofZ). For nonorientable surfaces only θ=0, π are allowed. Finally, we briefly comment on systems of spinning particles and make a comparison with the results for solitons in the O(3)-invariant nonlinear sigma model with space manifold M. (orig.)

  16. Single Crystal Surfaces

    Science.gov (United States)

    Aguilar-Santillan, Joaquin

    2014-06-01

    The present work studies (0001) Al2O3 and (111) Al2MgO4 wetting with pure molten Al by the sessile drop technique from 1073 K to 1473 K (800 °C to 1200 °C) under Ar at PO2 10-15 Pa. Al pure liquid wets a smooth and chemically homogeneous surface of an inert solid, the wetting driving force ( t, T) can be readily studied when surface solid roughness increases in the system. Both crystals planes (0001) Al2O3 and (111) Al2MgO4 have crystallographic surfaces with identical O-2 crystalline positions however considering Mg2+ content in Al2MgO4 structure may influence a reactive mode. Kinetic models results under similar experimental conditions show that Al wetting on (0001) Al2O3 is less reactive than (111) Al2MgO4, however at >1273 K (1000 °C) (0001) Al2O3 transformation occurs and a transition of wetting improves. The (111) Al2MgO4 and Al system promotes interface formations that slow its wetting process.

  17. Amphoteric surface active agents

    Directory of Open Access Journals (Sweden)

    Eissa, A.M. F.

    1995-10-01

    Full Text Available 2-[trimethyl ammonium, triethyl ammonium, pyridinium and 2-amino pyridinium] alkanoates, four series of surface active agents containing carbon chain C12, C14, C16 and C18carbon atoms, were prepared. Their structures were characterized by microanalysis, infrared (IR and nuclear magnetic resonance (NMR. Surface and interfacial tension, Krafft point, wetting time, emulsification power, foaming height and critical micelle concentration (cmc were determined and a comparative study was made between their chemical structure and surface active properties. Antimicrobial activity of these surfactants was also determined.

    Se prepararon cuatro series de agentes tensioactivos del tipo 2-[trimetil amonio, trietil amonio, piridinio y 2-amino piridinio] alcanoatos, que contienen cadenas carbonadas con C12, C14, C16 y C18 átomos de carbono.
    Se determinaron la tensión superficial e interfacial, el punto de Krafft, el tiempo humectante, el poder de emulsionamiento, la altura espumante y la concentración critica de miscela (cmc y se hizo un estudio comparativo entre la estructura química y sus propiedades tensioactivas. Se determinó también la actividad antimicrobiana de estos tensioactivos. Estas estructuras se caracterizaron por microanálisis, infrarrojo (IR y resonancia magnética nuclear (RMN.

  18. Conversion from surface wave to surface wave on reflection

    DEFF Research Database (Denmark)

    Novitsky, Andrey

    2010-01-01

    can be transmitted without changing its direction (nevertheless the amplitude varies). For other media parameters, only normally incident surface waves can be converted to surface waves. We propose applications of the predicted conversion as a beam splitter and polarization filter for surface waves.......We discuss the reflection and transmission of an incident surface wave to a pure surface wave state at another interface. This is allowed only for special media parameters: at least one of the media must be magnetic. We found such material characteristics that the obliquely incident surface wave...

  19. Biomechanical aspects of playing surfaces.

    Science.gov (United States)

    Nigg, B M; Yeadon, M R

    1987-01-01

    The purpose of this paper is to discuss some biomechanical aspects of playing surfaces with special focus on (a) surface induced injuries, (b) methodologies used to assess surfaces and (c) findings from various sports. The paper concentrates primarily on questions related to load on the athlete's body. Data from epidemiological studies suggest strongly that the surface is an important factor in the aetiology of injuries. Injury frequencies are reported to be significantly different for different surfaces in several sports. The methodologies used to assess surfaces with respect to load or performance include material tests and tests using experimental subjects. There is only little correlation between the results of these two approaches. Material tests used in many standardized test procedures are not validated which suggests that one should exercise restraint in the interpretation of these results. Point elastic surfaces are widely studied while area elastic surfaces have received little attention to date. Questions of energy losses on sport surfaces have rarely been studied scientifically.

  20. Nature Inspired Surface Coatings

    Science.gov (United States)

    Rubner, Michael

    2011-04-01

    Materials Scientists more and more are looking to nature for clues on how to create highly functional surface coatings with exceptional properties. The fog harvesting capabilities of the Namib Desert beetle, the beautiful iridescent colors of the hummingbird, and the super water repellant abilities of the Lotus leaf are but a few examples of the amazing properties developed over many years in the natural world. Nature also makes extensive use of the pH-dependent behavior of weak functional groups such as carboxylic acid and amine functional groups. This presentation will explore synthetic mimics to the nano- and microstructures responsible for these fascinating properties. For example, we have demonstrated a pH-induced porosity transition that can be used to create porous films with pore sizes that are tunable from the nanometer scale to the multiple micron scale. The pores of these films, either nano- or micropores, can be reversibly opened and closed by changes in solution pH. The ability to engineer pH-gated porosity transitions in heterostructured thin films has led to the demonstration of broadband anti-reflection coatings that mimic the anti-reflection properties of the moth eye and pH-tunable Bragg reflectors with a structure and function similar to that found in hummingbird wings and the Longhorn beetle. In addition, the highly textured honeycomb-like surfaces created by the formation of micron-scale pores are ideally suited for the creation of superhydrophobic surfaces that mimic the behavior of the self-cleaning lotus leaf. The development of synthetic "backbacks" on immune system cells that may one day ferry drugs to disease sites will also be discussed.

  1. Surface Nanobubbles Nucleate Microdroplets

    Science.gov (United States)

    Zhang, Xuehua; Lhuissier, Henri; Sun, Chao; Lohse, Detlef

    2014-04-01

    When a hydrophobic solid is in contact with water, surface nanobubbles often form at the interface. They have a lifetime many orders of magnitude longer than expected. Here, we show that they even withstand a temperature increase to temperatures close to the boiling point of bulk water; i.e., they do not nucleate larger bubbles ("superstability"). On the contrary, when the vapor-liquid contact line passes a nanobubble, a liquid film remains around it, which, after pinch-off, results in a microdroplet in which the nanobubbles continue to exist. Finally, the microdroplet evaporates and the nanobubble consequently bursts. Our results support that pinning plays a crucial role for nanobubble stability.

  2. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  3. Modeling surface imperfections in thin films and nanostructured surfaces

    DEFF Research Database (Denmark)

    Hansen, Poul-Erik; Madsen, J. S.; Jensen, S. A.

    2017-01-01

    Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection...

  4. Surface Chemistry in Nanoscale Materials

    Science.gov (United States)

    Biener, Jürgen; Wittstock, Arne; Baumann, Theodore F.; Weissmüller, Jörg; Bäumer, Marcus; Hamza, Alex V.

    2009-01-01

    Although surfaces or, more precisely, the surface atomic and electronic structure, determine the way materials interact with their environment, the influence of surface chemistry on the bulk of the material is generally considered to be small. However, in the case of high surface area materials such as nanoporous solids, surface properties can start to dominate the overall material behavior. This allows one to create new materials with physical and chemical properties that are no longer determined by the bulk material, but by their nanoscale architectures. Here, we discuss several examples, ranging from nanoporous gold to surface engineered carbon aerogels that demonstrate the tuneability of nanoporous solids for sustainable energy applications.

  5. Surface Chemistry in Nanoscale Materials

    Directory of Open Access Journals (Sweden)

    Alex V. Hamza

    2009-12-01

    Full Text Available Although surfaces or, more precisely, the surface atomic and electronic structure, determine the way materials interact with their environment, the influence of surface chemistry on the bulk of the material is generally considered to be small. However, in the case of high surface area materials such as nanoporous solids, surface properties can start to dominate the overall material behavior. This allows one to create new materials with physical and chemical properties that are no longer determined by the bulk material, but by their nanoscale architectures. Here, we discuss several examples, ranging from nanoporous gold to surface engineered carbon aerogels that demonstrate the tuneability of nanoporous solids for sustainable energy applications.

  6. Test surfaces useful for calibration of surface profilometers

    Science.gov (United States)

    Yashchuk, Valeriy V; McKinney, Wayne R; Takacs, Peter Z

    2013-12-31

    The present invention provides for test surfaces and methods for calibration of surface profilometers, including interferometric and atomic force microscopes. Calibration is performed using a specially designed test surface, or the Binary Pseudo-random (BPR) grating (array). Utilizing the BPR grating (array) to measure the power spectral density (PSD) spectrum, the profilometer is calibrated by determining the instrumental modulation transfer.

  7. Surface energy and surface tension of liquid metal nanodrops

    Directory of Open Access Journals (Sweden)

    Shebzukhov A.A.

    2011-05-01

    Full Text Available A unitary approach has been proposed for the calculation of surface energy and surface tension of nanoparticle being in equilibrium with its saturated vapor on both flat and curved surfaces at given temperature. The final equations involve parameters dependent on the type of premelting structure: bcc, fcc or hcp.

  8. Surface energy and surface tension of liquid metal nanodrops

    Science.gov (United States)

    Shebzukhova, M. A.; Shebzukhov, A. A.

    2011-05-01

    A unitary approach has been proposed for the calculation of surface energy and surface tension of nanoparticle being in equilibrium with its saturated vapor on both flat and curved surfaces at given temperature. The final equations involve parameters dependent on the type of premelting structure: bcc, fcc or hcp.

  9. Surface energy and surface tension of liquid metal nanodrops

    OpenAIRE

    Shebzukhov A.A.; Shebzukhova M.A.

    2011-01-01

    A unitary approach has been proposed for the calculation of surface energy and surface tension of nanoparticle being in equilibrium with its saturated vapor on both flat and curved surfaces at given temperature. The final equations involve parameters dependent on the type of premelting structure: bcc, fcc or hcp.

  10. Smooth surfaces from bilinear patches: Discrete affine minimal surfaces

    KAUST Repository

    Käferböck, Florian

    2013-06-01

    Motivated by applications in freeform architecture, we study surfaces which are composed of smoothly joined bilinear patches. These surfaces turn out to be discrete versions of negatively curved affine minimal surfaces and share many properties with their classical smooth counterparts. We present computational design approaches and study special cases which should be interesting for the architectural application. 2013 Elsevier B.V.

  11. Independent encoding of surface orientation and surface curvature.

    Science.gov (United States)

    Johnston, A; Passmore, P J

    1994-11-01

    Marr [(1982) Vision, San Francisco, Calif.: Freeman] proposed that we represent surface geometry in terms of a viewer-centred description of surface orientation and distance. This description is computed by a range of independent processing systems which take as input particular kinds of information present in images, like surface texture, shading, retinal disparity and motion parallax. The outputs of these modules are integrated in order to provide a unitary representation of the layout of visible surfaces. Higher order properties of surface geometry, like surface curvature, might be computed from this symbolic representation or might be encoded independently from the visual information available at the retinae. We measured surface slant and surface curvature discrimination thresholds for surface patches defined by shading, texture and retinal disparity as a function of the elevation of the illumination. We found that observers judgements about the curvature of local surface patches were too precise to be based on a symbolic representation of surface orientation and we conclude that surface curvature is computed directly from depth cues present in the retinal images.

  12. Concepts in surface physics

    CERN Document Server

    Desjonquères, M -C

    1993-01-01

    This textbook is intended as an introduction to surface science for graduate students. It began as a course of lectures that we gave at the University of Paris (Orsay). Its main objectives are twofold: to provide the reader with a compre­ hensive presentation of the basic principles and concepts of surface physics and to show the usefulness of these concepts in the real world by referring to experiments. It starts at a rather elementary level since it only requires a knowledge of solid state physics, quantum mechanics, thermodynamics and statistical physics which does not exceed the background usually taught to students early in their university courses. However, since it finally reaches an advanced level, we have tried to render it as self-contained as possible so that it remains accessible even to an unexperienced reader. Furthermore, the emphasis has been put on a pedagogical level rather than on a technical level. In this spirit, whenever possible, models which are simplified, but which contain the featu...

  13. Viscoelasticity of multicellular surfaces.

    Science.gov (United States)

    Pajic-Lijakovic, Ivana; Milivojevic, Milan

    2017-07-26

    Various modeling approaches have been applied to describe viscoelasticity of multicellular surfaces. The viscoelasticity is considered within three time regimes: (1) short time regime for milliseconds to seconds time scale which corresponds to sub-cellular level; (2) middle time regime for several tens of seconds to several minutes time scale which corresponds to cellular level; and (3) long time regime for several tens of minutes to several hours time scale which corresponds to supra-cellular level. Short and middle time regimes have been successfully elaborated in the literature, whereas long time viscoelasticity remains unclear. Long time regime accounts for collective cell migration. Collective cell migration could induce uncorrelated motility which has an impact to energy storage and dissipation during cell surface rearrangement. Uncorrelated motility influences: (1) volume fraction of migrating cells, (2) distribution of migrating cells, (3) shapes of migrating cell groups. These parameters influence mechanical coupling between migrating and resting subpopulations and consequently the constitutive model for long time regime. This modeling consideration indicates that additional experimental work is needed to confirm the feasibility of constitutive models which have been applied in literature for long time regime as: (1) relaxation of stress and strain, (2) storage and loss moduli as the function of time, (3) distribution of migrating cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Probing Anisotropic Surface Properties and Surface Forces of Fluorite Crystals.

    Science.gov (United States)

    Gao, Zhiyong; Xie, Lei; Cui, Xin; Hu, Yuehua; Sun, Wei; Zeng, Hongbo

    2018-02-20

    Fluorite is the most important mineral source for producing fluorine-based chemicals and materials in a wide range of engineering and technological applications. In this work, atomic force microscopy was employed, for the first time, to probe the surface interactions and adhesion energy of model oleic acid (a commonly used surface modification organics for fluorite) molecules on fluorite surfaces with different orientations in both air and aqueous solutions at different pH conditions. Fitted with the Derjaguin-Landau-Verwey-Overbeek theory, the force results during surface approaching demonstrate the anisotropy in the surface charge of different orientations, with the {111} surface exhibiting a higher magnitude of surface charge, which could be attributed to the difference in the atomic composition. The adhesion measured during surface retraction shows that model oleic acid molecules have a stronger adhesion with the {100} surface than with the {111} surface in both air and aqueous solutions. The anisotropic adhesion energy was analyzed in relation to the surface atom (especially calcium) activity, which was supported by the surface free energy results calculated based on a three-probe-liquid method. Each calcium atom on the {100} surface with four dangling bonds is more active than the calcium atom on the {111} surface with only one dangling bond, supported by a larger value of the Lewis acid component for the {100} surface. The model oleic acid molecules present in the ionic form at pH 9 exhibit a higher adhesion energy with fluorite surfaces as compared to their molecular form at pH 6, which was related to the surface activity of different forms. The adhesion energy measured in solution is much lower than that in air, indicating that the solvent exerts an important influence on the interactions of organic molecules with mineral surfaces. The results provide useful information on the fundamental understanding of surface interactions and adhesion energy of organic

  15. On-surface synthesis on a bulk insulator surface

    Science.gov (United States)

    Richter, Antje; Floris, Andrea; Bechstein, Ralf; Kantorovich, Lev; Kühnle, Angelika

    2018-04-01

    On-surface synthesis has rapidly emerged as a most promising approach to prepare functional molecular structures directly on a support surface. Compared to solution synthesis, performing chemical reactions on a surface offers several exciting new options: due to the absence of a solvent, reactions can be envisioned that are otherwise not feasible due to the insolubility of the reaction product. Perhaps even more important, the confinement to a two-dimensional surface might enable reaction pathways that are not accessible otherwise. Consequently, on-surface synthesis has attracted great attention in the last decade, with an impressive number of classical reactions transferred to a surface as well as new reactions demonstrated that have no classical analogue. So far, the majority of the work has been carried out on conducting surfaces. However, when aiming for electronic decoupling of the resulting structures, e.g. for the use in future molecular electronic devices, non-conducting surfaces are highly desired. Here, we review the current status of on-surface reactions demonstrated on the (10.4) surface of the bulk insulator calcite. Besides thermally induced C-C coupling of halogen-substituted aryls, photochemically induced [2  +  2] cycloaddition has been proven possible on this surface. Moreover, experimental evidence exists for coupling of terminal alkynes as well as diacetylene polymerization. While imaging of the resulting structures with dynamic atomic force microscopy provides a direct means of reaction verification, the detailed reaction pathway often remains unclear. Especially in cases where the presence of metal atoms is known to catalyze the corresponding solution chemistry reaction (e.g. in the case of the Ullmann reaction), disclosing the precise reaction pathway is of importance to understand and generalize on-surface reactivity on a bulk insulator surface. To this end, density-functional theory calculations have proven to provide atomic

  16. Solid surfaces : some theoretical aspects

    International Nuclear Information System (INIS)

    Das, M.P.

    1978-01-01

    An appraisal of the current situation concerning some of the theoretical aspects of solid surfaces is presented. First of all the characterization of the surfaces that involves the surface geometry and atomic composition for both the clean and adsorbed surfaces is discussed. Under this, the methods for determining the surface structure (such as low energy electron diffraction, field electron and field ion microscopy, photo emission spectroscopy and atomic scattering) and methods for determining the surface composition by the Auger electron spectroscopy are outlined. In the second part, emphasis is on the electronic structure of the clean and adsorbed surfaces. The measurements of ultra-violet and X-ray photo electron spectra are shown to yield the information about the surface electronic structure. In this context the many body effects such as, shake-up and relaxation energy etc. are discussed. Finally the status of the theory in relation to the experiments on angular resolved and polarization dependent photo emission are presented. (auth.)

  17. Solvay Conference on Surface Science

    CERN Document Server

    1988-01-01

    The articles collected in this volume give a broad overview of the current state of surface science. Pioneers in the field and researchers met together at this Solvay Conference to discuss important new developments in surface science, with an emphasis on the common area between solid state physics and physical chemistry. The contributions deal with the following subjects: structure of surfaces, surface science and catalysis, two-dimensional physics and phase transitions, scanning tunneling microscopy, surface scattering and surface dynamics, chemical reactions at surfaces, solid-solid interfaces and superlattices, and surface studies with synchrotron radiation. On each of these subjects an introductory review talk and a number of short research contributions are followed by extensive discussions, which appear in full in the text. This nineteenth Solvay Conference commemorates the 75th anniversary of the Solvay Institutes.

  18. Surface properties of beached plastics.

    Science.gov (United States)

    Fotopoulou, Kalliopi N; Karapanagioti, Hrissi K

    2015-07-01

    Studying plastic characteristics in the marine environment is important to better understand interaction between plastics and the environment. In the present study, high-density polyethylene (HDPE), polyethylene terephalate (PET), and polyvinyl chloride (PVC) samples were collected from the coastal environment in order to study their surface properties. Surface properties such as surface functional groups, surface topography, point of zero charge, and color change are important factors that change during degradation. Eroded HDPE demonstrated an altered surface topography and color and new functional groups. Eroded PET surface was uneven, yellow, and occasionally, colonized by microbes. A decrease in Fourier transform infrared (FTIR) peaks was observed for eroded PET suggesting that degradation had occurred. For eroded PVC, its surface became more lamellar and a new FTIR peak was observed. These surface properties were obtained due to degradation and could be used to explain the interaction between plastics, microbes, and pollutants.

  19. Thermochemical surface engineering of steels

    DEFF Research Database (Denmark)

    Thermochemical Surface Engineering of Steels provides a comprehensive scientific overview of the principles and different techniques involved in thermochemical surface engineering, including thermodynamics, kinetics principles, process technologies and techniques for enhanced performance of steels...

  20. Computer representation of molecular surfaces

    International Nuclear Information System (INIS)

    Max, N.L.

    1981-01-01

    This review article surveys recent work on computer representation of molecular surfaces. Several different algorithms are discussed for producing vector or raster drawings of space-filling models formed as the union of spheres. Other smoother surfaces are also considered

  1. Waveguiding with surface plasmon polaritons

    DEFF Research Database (Denmark)

    Han, Zhanghua; Bozhevolnyi, Sergey I.

    2014-01-01

    Surface plasmon polaritons (SPPs) are electromagnetic modes propagating along metal-dielectric interfaces. Various SPP modes can be supported by flat and curved, single and multiple surfaces, exhibiting remarkable properties, including the possibility of concentrating electromagnetic fields beyon...

  2. GEWEX Surface Radiation Budget (SRB)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NASA/GEWEX Surface Radiation Budget (SRB) Release-3.0 data sets contains global 3-hourly, daily, monthly/3-hourly, and monthly averages of surface and top-of...

  3. Preperation for a Clean Surface

    Directory of Open Access Journals (Sweden)

    Aurimas Ralys

    2012-12-01

    Full Text Available The article reviews techniques for preparing clean surfaces used in the manufacturing process, considers the types of clean surfaces and their role in modern production and provides the classification methods of arranging such surfaces. The paper also discusses the principles of methods for solvent cleaning, aqueous cleaning, ultrasonic cleaning, precision cleaning and mechanical cleaning. The study focuses on the possibility of adjusting a clean surface using a water flow, including cavitation.Article in Lithuanian

  4. Emerging trends in surface metrology

    DEFF Research Database (Denmark)

    Lonardo, P.M.; Lucca, D.A.; De Chiffre, Leonardo

    2002-01-01

    Recent advancements and some emerging trends in the methods and instruments used for surface and near surface characterisation are presented, considering the measurement of both topography and physical properties. In particular, surfaces that present difficulties in measurement or require new...... procedures are considered, with emphasis on measurements approaching the nanometre scale. Examples of new instruments and promising innovations for roughness measurement and surface integrity characterisation are presented. The new needs for tolerancing, traceability and calibration are also addressed....

  5. Surface Waves on Metamaterials Interfaces

    DEFF Research Database (Denmark)

    Takayama, Osamu; Shkondin, Evgeniy; Panah, Mohammad Esmail Aryaee

    2016-01-01

    We analyze surface electromagnetic waves supported at the interface between isotropic medium and effective anisotropic material that can be realized by alternating conductive and dielectrics layers. This configuration can host various types of surface waves and therefore can serve as a rich...... platform for applications of surface photonics. Most of these surface waves are directional and as such their propagation can be effectively controlled by changing wavelength or material parameters tuning....

  6. Interaction between heterogeneously charged surfaces: surface patches and charge modulation.

    Science.gov (United States)

    Ben-Yaakov, Dan; Andelman, David; Diamant, Haim

    2013-02-01

    When solid surfaces are immersed in aqueous solutions, some of their charges can dissociate and leave behind charged patches on the surface. Although the charges are distributed heterogeneously on the surface, most of the theoretical models treat them as homogeneous. For overall non-neutral surfaces, the assumption of surface charge homogeneity is rather reasonable since the leading terms of two such interacting surfaces depend on the nonzero average charge. However, for overall neutral surfaces the nature of the surface charge distribution is crucial in determining the intersurface interaction. In the present work we study the interaction between two charged surfaces across an aqueous solution for several charge distributions. The analysis is preformed within the framework of the linearized Poisson-Boltzmann theory. For periodic charge distributions the interaction is found to be repulsive at small separations, unless the two surface distributions are completely out-of-phase with respect to each other. For quenched random charge distributions we find that due to the presence of the ionic solution in between the surfaces, the intersurface repulsion dominates over the attraction in the linear regime of the Poisson-Boltzmann theory. The effect of quenched charge heterogeneity is found to be particularly substantial in the case of large charged domains.

  7. A motion-classification strategy based on sEMG-EEG signal combination for upper-limb amputees.

    Science.gov (United States)

    Li, Xiangxin; Samuel, Oluwarotimi Williams; Zhang, Xu; Wang, Hui; Fang, Peng; Li, Guanglin

    2017-01-07

    Most of the modern motorized prostheses are controlled with the surface electromyography (sEMG) recorded on the residual muscles of amputated limbs. However, the residual muscles are usually limited, especially after above-elbow amputations, which would not provide enough sEMG for the control of prostheses with multiple degrees of freedom. Signal fusion is a possible approach to solve the problem of insufficient control commands, where some non-EMG signals are combined with sEMG signals to provide sufficient information for motion intension decoding. In this study, a motion-classification method that combines sEMG and electroencephalography (EEG) signals were proposed and investigated, in order to improve the control performance of upper-limb prostheses. Four transhumeral amputees without any form of neurological disease were recruited in the experiments. Five motion classes including hand-open, hand-close, wrist-pronation, wrist-supination, and no-movement were specified. During the motion performances, sEMG and EEG signals were simultaneously acquired from the skin surface and scalp of the amputees, respectively. The two types of signals were independently preprocessed and then combined as a parallel control input. Four time-domain features were extracted and fed into a classifier trained by the Linear Discriminant Analysis (LDA) algorithm for motion recognition. In addition, channel selections were performed by using the Sequential Forward Selection (SFS) algorithm to optimize the performance of the proposed method. The classification performance achieved by the fusion of sEMG and EEG signals was significantly better than that obtained by single signal source of either sEMG or EEG. An increment of more than 14% in classification accuracy was achieved when using a combination of 32-channel sEMG and 64-channel EEG. Furthermore, based on the SFS algorithm, two optimized electrode arrangements (10-channel sEMG + 10-channel EEG, 10-channel sEMG + 20-channel

  8. Growth of rough epitaxial surfaces

    Indian Academy of Sciences (India)

    relevant to atomic surfaces would automatically be satisfied by largely heuristic classical terms. We therefore have to present electronic energy calculations in support of our model of surface growth. Among various physical processes which have been taken into account in models of growing interfaces, surface diffusion has ...

  9. Surface roughness from highlight structure

    NARCIS (Netherlands)

    Lu, Rong; Koenderink, Jan J.; Kappers, Astrid M L

    1999-01-01

    Highlights are due to specular reflection and cause the lustrous or mirrorlike appearance of many material surfaces. We investigated in detail the structure of highlight patterns that are due to material surface roughness. We interpret results in terms of a simple model of a random Gaussian surface.

  10. Surface properties of HMX crystal

    Science.gov (United States)

    Yee, R. Y.; Adicoff, A.; Dibble, E. J.

    1980-01-01

    The surface properties of Beta-HMX crystals were studied. The surface energies of three principal crystal faces were obtained by measuring contact angles with several reference liquids. The surface energies and polarity of the three crystal faces are found to be different.

  11. The surface energy of metals

    DEFF Research Database (Denmark)

    Vitos, Levente; Ruban, Andrei; Skriver, Hans Lomholt

    1998-01-01

    We have used density functional theory to establish a database of surface energies for low index surfaces of 60 metals in the periodic table. The data may be used as a consistent starting point for models of surface science phenomena. The accuracy of the database is established in a comparison...

  12. Surface mobilities on solid materials

    International Nuclear Information System (INIS)

    Binh, V.T.

    1983-01-01

    This book constitutes the proceedings of the NATO Advanced Study Institute on Surface Mobilities on Solid Materials held in France in 1981. The goal of the two-week meeting was to review up-to-date knowledge on surface diffusion, both theoretical and experimental, and to highlight those areas in which much more knowledge needs to be accumulated. Topics include theoretical aspects of surface diffusion (e.g., microscopic theories of D at zero coverage; statistical mechanical models and surface diffusion); surface diffusion at the atomic level (e.g., FIM studies of surface migration of single adatoms and diatomic clusters; field emission studies of surface diffusion of adsorbates); foreign adsorbate mass transport; self-diffusion mass transport (e.g., different driving forces for the matter transport along surfaces; measurements of the morphological evolution of tips); the role of surface diffusion in some fundamental and applied sciences (e.g. adatomadatom pair interactions and adlayer superstructure formation; surface mobility in chemical reactions and catalysis); and recent works on surface diffusion (e.g., preliminary results on surface self-diffusion measurements on nickel and chromium tips)

  13. Positron annihilation near fractal surfaces

    International Nuclear Information System (INIS)

    Lung, C.W.; Deng, K.M.; Xiong, L.Y.

    1991-07-01

    A model for positron annihilation in the sub-surface region near a fractal surface is proposed. It is found that the power law relationship between the mean positron implantation depth and incident positron energy can be used to measure the fractal dimension of the fractal surface in materials. (author). 10 refs, 2 figs

  14. Surface Effects in Magnetic Nanoparticles

    CERN Document Server

    Fiorani, Dino

    2005-01-01

    This volume is a collection of articles on different approaches to the investigation of surface effects on nanosized magnetic materials, with special emphasis on magnetic nanoparticles. The book aims to provide an overview of progress in the understanding of surface properties and surface driven effects in magnetic nanoparticles through recent results of different modeling, simulation, and experimental investigations.

  15. Alternative model of random surfaces

    International Nuclear Information System (INIS)

    Ambartzumian, R.V.; Sukiasian, G.S.; Savvidy, G.K.; Savvidy, K.G.

    1992-01-01

    We analyse models of triangulated random surfaces and demand that geometrically nearby configurations of these surfaces must have close actions. The inclusion of this principle drives us to suggest a new action, which is a modified Steiner functional. General arguments, based on the Minkowski inequality, shows that the maximal distribution to the partition function comes from surfaces close to the sphere. (orig.)

  16. Bacterial surface adaptation

    Science.gov (United States)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  17. Tunable surface plasmon devices

    Science.gov (United States)

    Shaner, Eric A [Rio Rancho, NM; Wasserman, Daniel [Lowell, MA

    2011-08-30

    A tunable extraordinary optical transmission (EOT) device wherein the tunability derives from controlled variation of the dielectric constant of a semiconducting material (semiconductor) in evanescent-field contact with a metallic array of sub-wavelength apertures. The surface plasmon resonance wavelength can be changed by changing the dielectric constant of the dielectric material. In embodiments of this invention, the dielectric material is a semiconducting material. The dielectric constant of the semiconducting material in the metal/semiconductor interfacial region is controllably adjusted by adjusting one or more of the semiconductor plasma frequency, the concentration and effective mass of free carriers, and the background high-frequency dielectric constant in the interfacial region. Thermal heating and/or voltage-gated carrier-concentration changes may be used to variably adjust the value of the semiconductor dielectric constant.

  18. Hydrological land surface modelling

    DEFF Research Database (Denmark)

    Ridler, Marc-Etienne Francois

    and disaster management. The objective of this study is to develop and investigate methods to reduce hydrological model uncertainty by using supplementary data sources. The data is used either for model calibration or for model updating using data assimilation. Satellite estimates of soil moisture and surface......Recent advances in integrated hydrological and soil-vegetation-atmosphere transfer (SVAT) modelling have led to improved water resource management practices, greater crop production, and better flood forecasting systems. However, uncertainty is inherent in all numerical models ultimately leading...... hydrological and tested by assimilating synthetic hydraulic head observations in a catchment in Denmark. Assimilation led to a substantial reduction of model prediction error, and better model forecasts. Also, a new assimilation scheme is developed to downscale and bias-correct coarse satellite derived soil...

  19. Surface enhanced thermo lithography

    KAUST Repository

    Coluccio, Maria Laura

    2017-01-13

    We used electroless deposition to fabricate clusters of silver nanoparticles (NPs) on a silicon substrate. These clusters are plasmonics devices that induce giant electromagnetic (EM) field increments. When those EM field are absorbed by the metal NPs clusters generate, in turn, severe temperature increases. Here, we used the laser radiation of a conventional Raman set-up to transfer geometrical patterns from a template of metal NPs clusters into a layer of thermo sensitive Polyphthalaldehyde (PPA) polymer. Temperature profile on the devices depends on specific arrangements of silver nanoparticles. In plane temperature variations may be controlled with (i) high nano-meter spatial precision and (ii) single Kelvin temperature resolution on varying the shape, size and spacing of metal nanostructures. This scheme can be used to generate strongly localized heat amplifications for applications in nanotechnology, surface enhanced thermo-lithography (SETL), biology and medicine (for space resolved cell ablation and treatment), nano-chemistry.

  20. Hydrological land surface modelling

    DEFF Research Database (Denmark)

    Ridler, Marc-Etienne Francois

    Recent advances in integrated hydrological and soil-vegetation-atmosphere transfer (SVAT) modelling have led to improved water resource management practices, greater crop production, and better flood forecasting systems. However, uncertainty is inherent in all numerical models ultimately leading...... and disaster management. The objective of this study is to develop and investigate methods to reduce hydrological model uncertainty by using supplementary data sources. The data is used either for model calibration or for model updating using data assimilation. Satellite estimates of soil moisture and surface...... hydrological and tested by assimilating synthetic hydraulic head observations in a catchment in Denmark. Assimilation led to a substantial reduction of model prediction error, and better model forecasts. Also, a new assimilation scheme is developed to downscale and bias-correct coarse satellite derived soil...

  1. The surface learned from nature

    Science.gov (United States)

    Lim, H.; Kim, W. D.

    2010-07-01

    In this work, I would like to introduce the emerging surface of nature. The surface in nature, has the multi and optimized function with well organized structure. There are so many examples that we learn and apply to technology. First example is self-cleaning surface. Some plants (such as lotus leaf, taro leaf) and the wings of many large-winged insects (such as moth, butterfly, dragonfly) remain their surface clean in the very dirty environment. This self cleaning effect is accomplished by the superhydrophobic surfaces which exhibit the water contact angle of more than 150° with low sliding angle. Generally, the superhydrophobic surface is made up the two factors. One is the surface composition having the low surface tension energy. The other is the surface morphology of hierarchical structure of micro and nano size. Because almost nature surface have the hierarchical structures range from macro to nano size, their topography strength their function to adjust the life in nature environment. The other example is the surface to use for drag reduction. The skin friction drag causes eruptions of air or water resulting in greater drag as the speed is increased. This drag requires more energy to overcome. The shark skin having the fine sharp-edged grooves about 0.1 mm wide known riblet reduces in skin friction drag by being far away the vortex. Among a lot of fuctional surface, the most exciting surface the back of stenocara a kind of desert beetles. Stenocara use the micrometre-sized patterns of hydrophobic, wax-coated and hydrophilic, non-waxy regions on their backs to capture water from fog. This fog-collecting structure improves the water collection of fog-capture film, condenser, engine, and future building. Here, the efforts to realize these emerging functional surfaces in nature on technology are reported with the fabrication method and their properties, especially for the control of surface wettability.

  2. Enhanced photochemistry on metal surfaces

    International Nuclear Information System (INIS)

    Goncher, G.M.; Parsons, C.A.; Harris, C.B.

    1984-01-01

    Due to the fast relaxation of molecular excited states in the vicinity of a metal or semiconductor surface, few observations of surface photochemistry have been reported. The following work concerns the surface-enhanced photo-reactions of a variety of physisorbed molecules on roughened Ag surfaces. In summary, photodecomposition leads to a graphitic surface carbon product which is monitored via surface-enhanced Raman scattering. In most cases an initial two-photon molecular absorption step followed by further absorption and fragmentation is thought to occur. Enhancement of the incident fields occurs through roughness-mediated surface plasmon resonances. This mechanism provides the amplified electromagnetic surface fields responsible for the observed photodecomposition. The photodecomposition experiments are performed under ultra-high vacuum. Surface characterization of the roughened surfaces was done by Scanning Electron Microscopy (SEM), and electron-stimulated emission. The SEM revealed morphology on the order of 300-400 A. This size of roughness feature, when modelled as isolated spheres should exhibit the well-known Mie resonances for light of the correct wavelengths. For protrusions existing on a surface these Mie resonances can be thought of as a coupling of the light with the surface plasmon. Experimental verification of these resonances was provided by the electron-stimulated light emission results. These showed that a polished Ag surface emitted only the expected transition radiation at the frequency of the Ag bulk plasmon. Upon roughening, however, a broad range of lower frequencies extending well into the visible are seen from electron irradiation of the surface. Large enhancements are expected for those frequencies which are able to couple into the surface modes

  3. Artificial TE-mode surface waves at metal surfaces mimicking surface plasmons.

    Science.gov (United States)

    Sun, Zhijun; Zuo, Xiaoliu; Guan, Tengpeng; Chen, Wei

    2014-02-24

    Manipulation of light in subwavelength scale can be realized with metallic nanostructures for TM-polarization components due to excitation of surface plasmons. TE-polarization components of light are usually excluded in subwavelength metal structures for mesoscopic optical interactions. Here we show that, by introducing very thin high index dielectric layers on structured metal surfaces, pseudo surface polarization currents can be induced near metal surfaces, which bring to excitation of artificial TE-mode surface waves at the composite meta-surfaces. This provides us a way to manipulate TE-polarized light in subwavelength scale. Typical properties of the artificial surface waves are further demonstrate for their excitation, propagation, optical transmission, and enhancement and resonances of the localized fields, mimicking those of surface plasmon waves.

  4. Water on a Hydrophobic surface

    Science.gov (United States)

    Scruggs, Ryan; Zhu, Mengjue; Poynor, Adele

    2012-02-01

    Hydrophobicity, meaning literally fear of water, is exhibited on the surfaces of non-stick cooking pans and water resistant clothing, on the leaves of the lotus plan, or even during the protein folding process in our bodies. Hydrophobicity is directly measured by determining a contact angle between water and an objects surface. Associated with a hydrophobic surface is the depletion layer, a low density region approximately 0.2 nm thick. We study this region by comparing data found in lab using surface plasmon resonance techniques to theoretical calculations. Experiments use gold slides coated in ODT and Mercapto solutions to model both hydrophobic and hydrophilic surfaces respectively.

  5. Surface-stabilized gold nanocatalysts

    Science.gov (United States)

    Dai, Sheng [Knoxville, TN; Yan, Wenfu [Oak Ridge, TN

    2009-12-08

    A surface-stabilized gold nanocatalyst includes a solid support having stabilizing surfaces for supporting gold nanoparticles, and a plurality of gold nanoparticles having an average particle size of less than 8 nm disposed on the stabilizing surfaces. The surface-stabilized gold nanocatalyst provides enhanced stability, such as at high temperature under oxygen containing environments. In one embodiment, the solid support is a multi-layer support comprising at least a first layer having a second layer providing the stabilizing surfaces disposed thereon, the first and second layer being chemically distinct.

  6. Tools for measuring surface cleanliness

    Energy Technology Data Exchange (ETDEWEB)

    Schroder, Mark Stewart (Hendersonville, NC); Woodmansee, Donald Ernest (Simpsonville, SC); Beadie, Douglas Frank (Greenville, SC)

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  7. Speckle phase near random surfaces

    Science.gov (United States)

    Chen, Xiaoyi; Cheng, Chuanfu; An, Guoqiang; Han, Yujing; Rong, Zhenyu; Zhang, Li; Zhang, Meina

    2018-03-01

    Based on Kirchhoff approximation theory, the speckle phase near random surfaces with different roughness is numerically simulated. As expected, the properties of the speckle phase near the random surfaces are different from that in far field. In addition, as scattering distances and roughness increase, the average fluctuations of the speckle phase become larger. Unusually, the speckle phase is somewhat similar to the corresponding surface topography. We have performed experiments to verify the theoretical simulation results. Studies in this paper contribute to understanding the evolution of speckle phase near a random surface and provide a possible way to identify a random surface structure based on its speckle phase.

  8. Phase diagrams for surface alloys

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Ruban, Andrei; Stoltze, Per

    1997-01-01

    We discuss surface alloy phases and their stability based on surface phase diagrams constructed from the surface energy as a function of the surface composition. We show that in the simplest cases of pseudomorphic overlayers there are four generic classes of systems, characterized by the sign...... is based on density-functional calculations using the coherent-potential approximation and on effective-medium theory. We give self-consistent density-functional results for the segregation energy and surface mixing energy for all combinations of the transition and noble metals. Finally we discuss...

  9. Laser surface texturing of tool steel: textured surfaces quality evaluation

    Science.gov (United States)

    Šugár, Peter; Šugárová, Jana; Frnčík, Martin

    2016-05-01

    In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

  10. Superhydrophobic surfaces fabricated by surface modification of alumina particles

    Science.gov (United States)

    Richard, Edna; Aruna, S. T.; Basu, Bharathibai J.

    2012-10-01

    The fabrication of superhydrophobic surfaces has attracted intense interest because of their widespread potential applications in various industrial fields. Recently, some attempts have been carried out to prepare superhydrophobic surfaces using metal oxide nanoparticles. In the present work, superhydrophobic surfaces were fabricated with low surface energy material on alumina particles with different sizes. It was found that particle size of alumina is an important factor in achieving stable superhydrophobic surface. It was possible to obtain alumina surface with water contact angle (WCA) of 156° and a sliding angle of Superhydrophobicity of the modified alumina is attributed to the combined effect of the micro-nanostructure and low surface energy of fatty acid on the surface. The surface morphology of the alumina powder and coatings was determined by FESEM. The stability of the coatings was assessed by conducting water immersion test. Effect of heat treatment on WCA of the coating was also studied. The transition of alumina from hydrophilic to superhydrophobic state was explained using Wenzel and Cassie models. The method is shown to have potential application for creating superhydrophobic surface on cotton fabrics.

  11. Topics in theoretical surface science

    Energy Technology Data Exchange (ETDEWEB)

    Todd, R.

    1991-10-25

    The energetics and structures of clean and adsorbate covered surfaces are investigated in this dissertation. First, the formalism, within the Corrected Effective Medium (CEM) method, for calculating the surface energy of a clean surface is derived. The surface energies for many different metals and their low index surfaces are presented. The minimization of the surface energy is then used to predict the multilayer relaxation of the Al(111), (100), Ni(100), (110) and Fe(100) surfaces. Extensions of the surface CEM formalism to calculate the binding energies of ordered adsorbates on metals surfaces are also derived. The minimization of the binding energy allowed determination of the binding heights, sites and the extent of induced multilayer relaxation for H and N atoms on the Fe(110), (100) and W(110) surfaces. The last topic deals with the dynamics of the epitaxial growth of metals on metal surfaces. The CEM method was first modified by making approximations to enable faster evaluations of the potential and its corresponding forces for molecular dynamics simulations. The goal of these simulations was to identify the important steps in the formation of equilibrium epitaxial structures. 180 refs., 31 figs., 18 tabs.

  12. Helium atom scattering from surfaces

    CERN Document Server

    1992-01-01

    High resolution helium atom scattering can be applied to study a number of interesting properties of solid surfaces with great sensitivity and accuracy. This book treats in detail experimental and theoretical aspects ofthis method as well as all current applications in surface science. The individual chapters - all written by experts in the field - are devoted to the investigation of surface structure, defect shapes and concentrations, the interaction potential, collective and localized surface vibrations at low energies, phase transitions and surface diffusion. Over the past decade helium atom scattering has gained widespread recognitionwithin the surface science community. Points in its favour are comprehensiveunderstanding of the scattering theory and the availability of well-tested approximation to the rigorous theory. This book will be invaluable to surface scientists wishing to make an informed judgement on the actual and potential capabilities of this technique and its results.

  13. Riemann surfaces of infinite genus

    CERN Document Server

    Feldman, Joel S; Trubowitz, Eugene

    2003-01-01

    In this book, Riemann surfaces of infinite genus are constructed geometrically by pasting together plane domains and handles. To achieve a meaningful generalization of the classical theory of Riemann surfaces to the case of infinite genus, one must impose restrictions on the asymptotic behavior of the Riemann surface. In the construction carried out here, these restrictions are formulated in terms of the sizes and locations of the handles and in terms of the gluing maps. The approach used in this book has two main attractions. The first is that much of the classical theory of Riemann surfaces, including the Torelli theorem, can be generalized to this class. The second is that solutions of Kadomcev-Petviashvilli equations can be expressed in terms of theta functions associated with Riemann surfaces of infinite genus constructed in the book. Both of these are developed here. The authors also present in detail a number of important examples of Riemann surfaces of infinite genus (hyperelliptic surfaces of infinit...

  14. Beauville Surfaces and Groups 2012

    CERN Document Server

    Garion, Shelly; Vdovina, Alina

    2015-01-01

    This collection of surveys and research articles explores a fascinating class of varieties: Beauville surfaces. It is the first time that these objects are discussed from the points of view of algebraic geometry as well as group theory. The book also includes various open problems and conjectures related to these surfaces. Beauville surfaces are a class of rigid regular surfaces of general type, which can be described in a purely algebraic combinatoric way. They play an important role in different fields of mathematics like algebraic geometry, group theory and number theory. The notion of Beauville surface was introduced by Fabrizio Catanese in 2000 and, after the first systematic study of these surfaces by Ingrid Bauer, Fabrizio Catanese and Fritz Grunewald, there has been an increasing interest in the subject. These proceedings reflect the topics of the lectures presented during the workshop ‘Beauville Surfaces and Groups 2012’, held at Newcastle University, UK in June 2012. This conference brought toge...

  15. Surface mount component jig

    Science.gov (United States)

    Kronberg, James W.

    1990-08-07

    A device for bending and trimming the pins of a dual-inline-package component and the like for surface mounting rather than through mounting to a circuit board comprises, in a first part, in pin cutter astride a holder having a recess for holding the component, a first spring therebetween, and, in a second part, two flat members pivotally interconnected by a hinge and urged to an upward peaked position from a downward peaked position by a second spring. As a downward force is applied to the pin cutter it urges the holder downward, assisted by the first spring and a pair of ridges riding on shoulders of the holder, to carry the component against the upward peaked flat members which guide the pins outwardly. As the holder continues downwardly, the flat members pivot to the downward peaked position bending the pins upwardly against the sides of the holder. When the downward movement is met with sufficient resistance, the ridges of the pin cutter ride over the holder's shoulders to continue downward to cut any excess length of pin.

  16. Decontamination of surfaces

    International Nuclear Information System (INIS)

    Dlouhy, Z.

    1977-01-01

    Main sources and characteristics of wastes are discussed and basic data are given on the amount and nature of all wastes produced during the treatment of liquid and gaseous wastes in nuclear power plants with boiling (BWR), pressurized (PWR), and advanced gas-cooled (MGR) reactors of a 1,000 MW(e) installed power. A short comparison of methods used for liquid radioactive waste treatment is given. Methods are shortly described for solidification of concentrates, sludges, resin slurries, and for immobilization of radioactive substances in other solid wastes. An approach to the problem of waste storage in a densely populated country is given. The part dealing with surface decontamination problems is dedicated to contaminant sources in gas and water-cooled reactors, to decontaminating agents used in reactor technology, and to the description of most important methods used in decontamination practice. A short evaluation of protective coatings from the point of view of their further successful decontamination is given. (orig./HK) [de

  17. Adhesion energy, surface traction and surface tension in liquid xenon

    Indian Academy of Sciences (India)

    Abstract. We calculated the adhesion energy, the surface traction and the surface energy of liquid xenon using molecular dynamics (MD) simulation. The value of the adhesion energy for liquid xenon at a reduced density of 0.630 was found to be 0.591 J/m2 and the surface traction has a peak at z = 3.32 Å. It was observed ...

  18. Adhesion energy, surface traction and surface tension in liquid xenon

    Indian Academy of Sciences (India)

    We calculated the adhesion energy, the surface traction and the surface energy of liquid xenon using molecular dynamics (MD) simulation. The value of the adhesion energy for liquid xenon at a reduced density of 0.630 was found to be 0.591 J/m2 and the surface traction has a peak at = 3.32 Å. It was observed that the ...

  19. Surface resonance on the NiFe(001) alloy surface

    Czech Academy of Sciences Publication Activity Database

    Ondráček, Martin; Máca, František; Kudrnovský, Josef; Redinger, J.

    2006-01-01

    Roč. 56, č. 1 (2006), s. 69-74 ISSN 0011-4626. [Symposium on Surface Physics /10./. Praha, 11.07.2005-15.07.2005] R&D Projects: GA ČR(CZ) GA202/04/0583 Institutional research plan: CEZ:AV0Z10100520 Keywords : NiFe alloy * surface electronic structure * surface geometry * density functional calculation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.568, year: 2006

  20. Surface Energy and Setting Process of Contacting Surfaces

    Directory of Open Access Journals (Sweden)

    M. V. Musokhranov

    2014-01-01

    Full Text Available The paper deals with a challenge in terms of ensuring an accuracy of the relative position of the conjugated surfaces that is to determine a coefficient of friction. To solve it, there is a proposal to use the surface energy, as a tool that influences the contacting parts nature. Presently, energy of the surface layers at best is only stated, but not used in practice.Analysis of the conditions of interaction between two contacting surfaces, such as seizing and setting cannot be explained only from the position of the roughness parameters. It is found that these phenomena are explained by the appearing gripe (setting bridges, which result from the energy of interaction between two or more adjacent surfaces. The emerging phenomenon such as micro welding, i.e. occurring bonds, is caused by the overflow of energy, according to the theory of physics, from the surface with a high level of energy to the surface with the smaller one to balance the system as a whole.The paper shows that through the use of process, controlling the depth of the surface layer and creating a certain structure, the energy level of the material as a whole can be specified. And this will allow us to provide the necessary performance and mechanical properties. It means to create as many gripe bridges as possible to ensure continuous positioning i.e. a fixed connection of the contacting surfaces.It was determined that to increase a value of the friction coefficient, the physical and mechanical properties of the surface layer of the parts material must be taken into account, namely, in the part body accumulate the energy to be consumed for forming the surface.The paper gives recommendations for including the parts of the surface energy in the qualitative indicators of characteristics. This will make a technologist, when routing a process, to choose such operations and modes to provide the designer-specified parameters not only of the accuracy and surface finish, but also of the

  1. Advances in surfaces and osseointegration in implantology. Biomimetic surfaces

    Science.gov (United States)

    Albertini, Matteo; Fernandez-Yague, Marc; Lázaro, Pedro; Herrero-Climent, Mariano; Bullon, Pedro; Gil, Francisco-Javier

    2015-01-01

    The present work is a revision of the processes occurring in osseointegration of titanium dental implants according to different types of surfaces -namely, polished surfaces, rough surfaces obtained from subtraction methods, as well as the new hydroxyapatite biomimetic surfaces obtained from thermochemical processes. Hydroxyapatite’s high plasma-projection temperatures have proven to prevent the formation of crystalline apatite on the titanium dental implant, but lead to the formation of amorphous calcium phosphate (i.e., with no crystal structure) instead. This layer produce some osseointegration yet the calcium phosphate layer will eventually dissolve and leave a gap between the bone and the dental implant, thus leading to osseointegration failure due to bacterial colonization. A new surface -recently obtained by thermochemical processes- produces, by crystallization, a layer of apatite with the same mineral content as human bone that is chemically bonded to the titanium surface. Osseointegration speed was tested by means of minipigs, showing bone formation after 3 to 4 weeks, with the security that a dental implant can be loaded. This surface can be an excellent candidate for immediate or early loading procedures. Key words:Dental implants, implants surfaces, osseointegration, biomimetics surfaces. PMID:25662555

  2. Airport Surface Network Architecture Definition

    Science.gov (United States)

    Nguyen, Thanh C.; Eddy, Wesley M.; Bretmersky, Steven C.; Lawas-Grodek, Fran; Ellis, Brenda L.

    2006-01-01

    Currently, airport surface communications are fragmented across multiple types of systems. These communication systems for airport operations at most airports today are based dedicated and separate architectures that cannot support system-wide interoperability and information sharing. The requirements placed upon the Communications, Navigation, and Surveillance (CNS) systems in airports are rapidly growing and integration is urgently needed if the future vision of the National Airspace System (NAS) and the Next Generation Air Transportation System (NGATS) 2025 concept are to be realized. To address this and other problems such as airport surface congestion, the Space Based Technologies Project s Surface ICNS Network Architecture team at NASA Glenn Research Center has assessed airport surface communications requirements, analyzed existing and future surface applications, and defined a set of architecture functions that will help design a scalable, reliable and flexible surface network architecture to meet the current and future needs of airport operations. This paper describes the systems approach or methodology to networking that was employed to assess airport surface communications requirements, analyze applications, and to define the surface network architecture functions as the building blocks or components of the network. The systems approach used for defining these functions is relatively new to networking. It is viewing the surface network, along with its environment (everything that the surface network interacts with or impacts), as a system. Associated with this system are sets of services that are offered by the network to the rest of the system. Therefore, the surface network is considered as part of the larger system (such as the NAS), with interactions and dependencies between the surface network and its users, applications, and devices. The surface network architecture includes components such as addressing/routing, network management, network

  3. Chemical stabilization of graphite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bistrika, Alexander A.; Lerner, Michael M.

    2018-04-03

    Embodiments of a device, or a component of a device, including a stabilized graphite surface, methods of stabilizing graphite surfaces, and uses for the devices or components are disclosed. The device or component includes a surface comprising graphite, and a plurality of haloaryl ions and/or haloalkyl ions bound to at least a portion of the graphite. The ions may be perhaloaryl ions and/or perhaloalkyl ions. In certain embodiments, the ions are perfluorobenzenesulfonate anions. Embodiments of the device or component including stabilized graphite surfaces may maintain a steady-state oxidation or reduction surface current density after being exposed to continuous oxidation conditions for a period of at least 1-100 hours. The device or component is prepared by exposing a graphite-containing surface to an acidic aqueous solution of the ions under oxidizing conditions. The device or component can be exposed in situ to the solution.

  4. Drop impact on superheated surfaces.

    Science.gov (United States)

    Tran, Tuan; Staat, Hendrik J J; Prosperetti, Andrea; Sun, Chao; Lohse, Detlef

    2012-01-20

    At the impact of a liquid droplet on a smooth surface heated above the liquid's boiling point, the droplet either immediately boils when it contacts the surface ("contact boiling"), or without any surface contact forms a Leidenfrost vapor layer towards the hot surface and bounces back ("gentle film boiling"), or both forms the Leidenfrost layer and ejects tiny droplets upward ("spraying film boiling"). We experimentally determine conditions under which impact behaviors in each regime can be realized. We show that the dimensionless maximum spreading γ of impacting droplets on the heated surfaces in both gentle and spraying film boiling regimes shows a universal scaling with the Weber number We (γ~We(2/5)), which is much steeper than for the impact on nonheated (hydrophilic or hydrophobic) surfaces (γ~We(1/4)). We also interferometrically measure the vapor thickness under the droplet. © 2012 American Physical Society

  5. Surface Detection using Round Cut

    DEFF Research Database (Denmark)

    Dahl, Vedrana Andersen; Dahl, Anders Bjorholm; Larsen, Rasmus

    2014-01-01

    We propose an iterative method for detecting closed surfaces in a volumetric data, where an optimal search is performed in a graph build upon a triangular mesh. Our approach is based on previous techniques for detecting an optimal terrain-like or tubular surface employing a regular grid. Unlike...... similar adaptations for triangle meshes, our method is capable of capturing complex geometries by iteratively refining the surface, where we obtain a high level of robustness by applying explicit mesh processing to intermediate results. Our method uses on-surface data support, but it also exploits data...... information about the region inside and outside the surface. This provides additional robustness to the algorithm. We demonstrate the capabilities of the approach by detecting surfaces of CT scanned objects....

  6. Friction surfaced Stellite6 coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rao, K. Prasad; Damodaram, R. [Department of Metallurgical and Materials Engineering - Indian Institute of Technology Madras, Chennai 600 036 (India); Rafi, H. Khalid, E-mail: khalidrafi@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Ram, G.D. Janaki [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Reddy, G. Madhusudhan [Metal Joining Group, Defence Metallurgical Research Laboratory (DMRL) Kanchanbagh, Hyderabad 500 058 (India); Nagalakshmi, R. [Welding Research Institute, Bharat Heavy Electricals Limited, Tiruchirappalli 620 014 (India)

    2012-08-15

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: Black-Right-Pointing-Pointer Stellite6 used as coating material for friction surfacing. Black-Right-Pointing-Pointer Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. Black-Right-Pointing-Pointer Finer and uniformly distributed carbides in friction surfaced coatings. Black-Right-Pointing-Pointer Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  7. Friction surfaced Stellite6 coatings

    International Nuclear Information System (INIS)

    Rao, K. Prasad; Damodaram, R.; Rafi, H. Khalid; Ram, G.D. Janaki; Reddy, G. Madhusudhan; Nagalakshmi, R.

    2012-01-01

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: ► Stellite6 used as coating material for friction surfacing. ► Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. ► Finer and uniformly distributed carbides in friction surfaced coatings. ► Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  8. Undergraduate Laboratory for Surface Science

    Science.gov (United States)

    Okumura, Mitchio; Beauchamp, Jesse L.; Dickert, Jeffrey M.; Essy, Blair R.; Claypool, Christopher L.

    1996-02-01

    Surface science has developed into a multidisciplinary field of research with applications ranging from heterogeneous catalysis to semiconductor etching (1). Aspects of surface chemistry are now included in physical chemistry textbooks (2) and undergraduate curricula (3), but the perceived cost and complexity of equipment has deterred the introduction of surface science methods in undergraduate laboratories (4). Efforts to expose chemistry undergraduates to state-of-the-art surface instrumentation have just begun (5). To provide our undergraduates with hands-on experience in using standard techniques for characterizing surface morphology, adsorbates, kinetics, and reaction mechanisms, we have developed a set of surface science experiments for our physical chemistry laboratory sequence. The centerpiece of the laboratory is an ultrahigh vacuum (UHV) chamber for studies of single crystal surfaces. This instrument, shown in the figure, has surface analysis capabilities including low energy electron diffraction (LEED), Auger spectroscopy, and temperature-programmed desorption (TPD). The laboratory exercises involve experiments on the well-studied Pt(111) surface. Students prepare a previously mounted single crystal sample by sputtering it with an argon ion gun and heating it under O2. Electron diffraction patterns from the cleaned surface are then obtained with a reverse view LEED apparatus (Princeton Instruments). Images are captured by a charge-coupled device (CCD) camera interfaced to a personal computer for easy downloading and subsequent analysis. Although the LEED images from a Pt(111) surface can be readily interpreted using simple diffraction arguments, this lab provides an excellent context for introducing Miller indices and reciprocal lattices (6). The surface chemical composition can be investigated by Auger spectroscopy, using the LEED apparatus as a simple energy analyzer. The temperature programmed desorption experiment, which is nearly complete, will be

  9. How old is surface science?

    International Nuclear Information System (INIS)

    Paparazzo, E.

    2004-01-01

    Philosophical and literary testimonies from the Classical World (5th century B.C. to 3rd century A.D.) involving solid surfaces are reviewed. Plato thought the surface to be a real entity, whereas Aristotle considered it to possess an unqualified existence, i.e. not to be a substance, but just an accidental entity. The Old Stoics asserted that surfaces do not possess any physical existence, although the Stoic philosopher Posidonius--apparently the only exception in his school--held them to exist both in thought and reality. While both the Atomists and the Epicureans were very little interested in them, the Sceptic philosopher Sextus Empiricus considered surfaces to be the limits of a body, although he maintained that both the view that they are corporeal or the view that they are incorporeal present unsurmountable difficulties. Among Roman authors, the testimony from Pliny the Elder is mostly concerned with metallic surfaces, chemical change occurring there, and surface treatments used in antiquity. Besides the philosophical motivations, the implications of the testimonies are discussed in the light of surface science. The purely geometrical surface of Plato is found to compare favorably to single-crystal surface, Posidonius' 'corporeal' surface is best likened to an air-oxidized, or otherwise ambient-modified surface, and ancient accounts on mixture are compared to XPS results obtained in adhesion studies of enameled steels. I argue that the long-standing dominance of Aristotle's view from antiquity onwards may have had a part in delaying theoretical speculation into solid surfaces

  10. Spectra of resonance surface photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Antsiferov, V.V.; Smirnov, G.I.; Telegin, G.G. [Budker Nuclear Physics Institute, Novosibirsk (Russian Federation)

    1995-09-01

    The theory of nonactivated electron transfer between atoms interacting reasonantly with coherent radiation and a metal surface is developed. The spectral resonances in photoabsorption and surface photoionization are found to be related to nonlinear interference effects in the interaction between discrete atomic levels and the continuum formed by the quasi-continuous electron spectrum of a normal metal. The asymmetry in the resonance surface photoionization spectrum is shown to have a shape typical of the Fano autoionization resonances. 18 refs.

  11. Genera of minimal balance surfaces

    International Nuclear Information System (INIS)

    Fischer, W.; Koch, E.

    1989-01-01

    The genus of a three-periodic intersection-free surface in R 3 refers to a primitive unit cell of its symmetry group. Two procedures for the calculation of the genus are described: (1) by means of labyrinth graphs; (2) via the Euler characteristic derived from a tiling on the surface. In both cases new formulae based on crystallographic concepts are given. For all known minimal balance surfaces the genera and the labyrinth graphs are tabulated. (orig.)

  12. How old is surface science?

    Energy Technology Data Exchange (ETDEWEB)

    Paparazzo, E. E-mail: paparazzo@ism.cnr.it

    2004-01-01

    Philosophical and literary testimonies from the Classical World (5th century B.C. to 3rd century A.D.) involving solid surfaces are reviewed. Plato thought the surface to be a real entity, whereas Aristotle considered it to possess an unqualified existence, i.e. not to be a substance, but just an accidental entity. The Old Stoics asserted that surfaces do not possess any physical existence, although the Stoic philosopher Posidonius--apparently the only exception in his school--held them to exist both in thought and reality. While both the Atomists and the Epicureans were very little interested in them, the Sceptic philosopher Sextus Empiricus considered surfaces to be the limits of a body, although he maintained that both the view that they are corporeal or the view that they are incorporeal present unsurmountable difficulties. Among Roman authors, the testimony from Pliny the Elder is mostly concerned with metallic surfaces, chemical change occurring there, and surface treatments used in antiquity. Besides the philosophical motivations, the implications of the testimonies are discussed in the light of surface science. The purely geometrical surface of Plato is found to compare favorably to single-crystal surface, Posidonius' 'corporeal' surface is best likened to an air-oxidized, or otherwise ambient-modified surface, and ancient accounts on mixture are compared to XPS results obtained in adhesion studies of enameled steels. I argue that the long-standing dominance of Aristotle's view from antiquity onwards may have had a part in delaying theoretical speculation into solid surfaces.

  13. Wettability of natural superhydrophobic surfaces.

    Science.gov (United States)

    Webb, Hayden K; Crawford, Russell J; Ivanova, Elena P

    2014-08-01

    Since the description of the 'Lotus Effect' by Barthlott and Neinhuis in 1997, the existence of superhydrophobic surfaces in the natural world has become common knowledge. Superhydrophobicity is associated with a number of possible evolutionary benefits that may be bestowed upon an organism, ranging from the ease of dewetting of their surfaces and therefore prevention of encumbrance by water droplets, self-cleaning and removal of particulates and potential pathogens, and even to antimicrobial activity. The superhydrophobic properties of natural surfaces have been attributed to the presence of hierarchical microscale (>1 μm) and nanoscale (typically below 200 nm) structures on the surface, and as a result, the generation of topographical hierarchy is usually considered of high importance in the fabrication of synthetic superhydrophobic surfaces. When one surveys the breadth of data available on naturally existing superhydrophobic surfaces, however, it can be observed that topographical hierarchy is not present on all naturally superhydrophobic surfaces; in fact, the only universal feature of these surfaces is the presence of a sophisticated nanoscale structure. Additionally, several natural surfaces, e.g. those present on rose petals and gecko feet, display high water contact angles and high adhesion of droplets, due to the pinning effect. These surfaces are not truly superhydrophobic, and lack significant degrees of nanoscale roughness. Here, we discuss the phenomena of superhydrophobicity and pseudo-superhydrophobicity in nature, and present an argument that while hierarchical surface roughness may aid in the stability of the superhydrophobic effect, it is nanoscale surface architecture alone that is the true determinant of superhydrophobicity. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Implant surfaces and interface processes.

    Science.gov (United States)

    Kasemo, B; Gold, J

    1999-06-01

    The past decades and current R&D of biomaterials and medical implants show some general trends. One major trend is an increased degree of functionalization of the material surface, better to meet the demands of the biological host system. While the biomaterials of the past and those in current use are essentially bulk materials (metals, ceramics, polymers) or special compounds (bioglasses), possibly with some additional coating (e.g., hydroxyapatite), the current R&D on surface modifications points toward much more complex and multifunctional surfaces for the future. Such surface modifications can be divided into three classes, one aiming toward an optimized three-dimensional physical microarchitecture of the surface (pore size distributions, "roughness", etc.), the second one focusing on the (bio) chemical properties of surface coatings and impregnations (ion release, multi-layer coatings, coatings with biomolecules, controlled drug release, etc.), and the third one dealing with the viscoelastic properties (or more generally the micromechanical properties) of material surfaces. These properties are expected to affect the interfacial processes cooperatively, i.e., there are likely synergistic effects between and among them: The surface is "recognized" by the biological system through the combined chemical and topographic pattern of the surface, and the viscoelastic properties. In this presentation, the development indicated above is discussed briefly, and current R&D in this area is illustrated with a number of examples from our own research. The latter include micro- and nanofabrication of surface patterns and topographies by the use of laser machining, photolithographic techniques, and electron beam and colloidal lithographies to produce controlled structures on implant surfaces in the size range 10 nm to 100 microns. Examples of biochemical modifications include mono- or lipid membranes and protein coatings on different surfaces. A new method to evaluate, e

  15. Antibacterial surface design - Contact kill

    Science.gov (United States)

    Kaur, Rajbir; Liu, Song

    2016-08-01

    Designing antibacterial surfaces has become extremely important to minimize Healthcare Associated Infections which are a major cause of mortality worldwide. A previous biocide-releasing approach is based on leaching of encapsulated biocides such as silver and triclosan which exerts negative impacts on the environment and potentially contributes to the development of bacterial resistance. This drawback of leachable compounds led to the shift of interest towards a more sustainable and environmentally friendly approach: contact-killing surfaces. Biocides that can be bound onto surfaces to give the substrates contact-active antibacterial activity include quaternary ammonium compounds (QACs), quaternary phosphoniums (QPs), carbon nanotubes, antibacterial peptides, and N-chloramines. Among the above, QACs and N-chloramines are the most researched contact-active biocides. We review the engineering of contact-active surfaces using QACs or N-chloramines, the modes of actions as well as the test methods. The charge-density threshold of cationic surfaces for desired antibacterial efficacy and attempts to combine various biocides for the generation of new contact-active surfaces are discussed in detail. Surface positive charge density is identified as a key parameter to define antibacterial efficacy. We expect that this research field will continue to attract more research interest in view of the potential impact of self-disinfective surfaces on healthcare-associated infections, food safety and corrosion/fouling resistance required on industrial surfaces such as oil pipes and ship hulls.

  16. Radioactive Probes on Ferromagnetic Surfaces

    CERN Multimedia

    2002-01-01

    On the (broad) basis of our studies of nonmagnetic radioactive probe atoms on magnetic surfaces and at interfaces, we propose to investigate the magnetic interaction of magnetic probe atoms with their immediate environment, in particular of rare earth (RE) elements positioned on and in ferromagnetic surfaces. The preparation and analysis of the structural properties of such samples will be performed in the UHV chamber HYDRA at the HMI/Berlin. For the investigations of the magnetic properties of RE atoms on surfaces Perturbed Angular Correlation (PAC) measurements and Mössbauer Spectroscopy (MS) in the UHV chamber ASPIC (Apparatus for Surface Physics and Interfaces at CERN) are proposed.

  17. Are Vicinal Metal Surfaces Stable?

    DEFF Research Database (Denmark)

    Frenken, J. W. M.; Stoltze, Per

    1999-01-01

    We use effective medium theory to demonstrate that the energies of many metal surfaces are lowered when these surfaces are replaced by facets with lower-index orientations. This implies that the low-temperature equilibrium shapes of many metal crystals should be heavily faceted. The predicted...... instability of vicinal metal surfaces is at variance with the almost generally observed stability of these surfaces. We argue that the unstable orientations undergo a defaceting transition at relatively low temperatures, driven by the high vibrational entropy of steps....

  18. Surface composition and surface properties of water hyacinth ...

    African Journals Online (AJOL)

    The surface composition and surface properties of water hyacinth (Eichhornia crassipes) root biomass were studied before and after extraction with dilute nitric acid and toluene/ethanol (2/1, v/v) followed by ethanol, using Fourier Transform Infra-red (FT-IR) spectroscopy, thermogravimetric analysis, x-ray diffraction, ...

  19. Analysis of cell surface antigens by Surface Plasmon Resonance imaging

    NARCIS (Netherlands)

    Stojanovic, Ivan; Schasfoort, Richardus B.M.; Terstappen, Leonardus Wendelinus Mathias Marie

    2013-01-01

    Surface Plasmon Resonance (SPR) is most commonly used to measure bio-molecular interactions. SPR is used significantly less frequent for measuring whole cell interactions. Here we introduce a method to measure whole cells label free using the specific binding of cell surface antigens expressed on

  20. Investigation of surface roughness on etched glass surfaces

    International Nuclear Information System (INIS)

    Papa, Z.; Budai, J.; Farkas, B.; Toth, Z.

    2011-01-01

    Roughening the surface of solar cells is a common practice within the photovoltaic industry as it reduces reflectance, and thus enhances the performance of devices. In this work the relationship between reflectance characterized by the haze parameter, surface roughness and optical properties was investigated. To achieve this goal, model samples were prepared by hydrofluoric acid etching of glass for various times and measured by optical microscopy, spectroscopic ellipsometry, scanning electron microscopy, and atomic force microscopy. Our investigation showed that the surface reflectance was decreased not only by the roughening of the surface but also by the modification of the depth profile and lowering of the refractive index of the surface domain of the samples.

  1. Surface Modification and Surface - Subsurface Exchange Processes on Europa

    Science.gov (United States)

    Phillips, C. B.; Molaro, J.; Hand, K. P.

    2017-12-01

    The surface of Jupiter's moon Europa is modified by exogenic processes such as sputtering, gardening, radiolysis, sulfur ion implantation, and thermal processing, as well as endogenic processes including tidal shaking, mass wasting, and the effects of subsurface tectonic and perhaps cryovolcanic activity. New materials are created or deposited on the surface (radiolysis, micrometeorite impacts, sulfur ion implantation, cryovolcanic plume deposits), modified in place (thermal segregation, sintering), transported either vertically or horizontally (sputtering, gardening, mass wasting, tectonic and cryovolcanic activity), or lost from Europa completely (sputtering, plumes, larger impacts). Some of these processes vary spatially, as visible in Europa's leading-trailing hemisphere brightness asymmetry. Endogenic geologic processes also vary spatially, depending on terrain type. The surface can be classified into general landform categories that include tectonic features (ridges, bands, cracks); disrupted "chaos-type" terrain (chaos blocks, matrix, domes, pits, spots); and impact craters (simple, complex, multi-ring). The spatial distribution of these terrain types is relatively random, with some differences in apex-antiapex cratering rates and latitudinal variation in chaos vs. tectonic features. In this work, we extrapolate surface processes and rates from the top meter of the surface in conjunction with global estimates of transport and resurfacing rates. We combine near-surface modification with an estimate of surface-subsurface (and vice versa) transport rates for various geologic terrains based on an average of proposed formation mechanisms, and a spatial distribution of each landform type over Europa's surface area. Understanding the rates and mass balance for each of these processes, as well as their spatial and temporal variability, allows us to estimate surface - subsurface exchange rates over the average surface age ( 50myr) of Europa. Quantifying the timescale

  2. Use of the Photo-Electromyogram to Objectively Diagnose and Monitor Treatment of Post-TBI Light Sensitivity

    Science.gov (United States)

    2015-10-01

    due to contact sports at both the school and professional level. At present there are no biological markers or tests that can be used to objectively...corneal nerve damage and peripheral neuropathy and in diet -induced obesity and type 2 diabetic rats. Invest Ophthalmol Vis Sci. 2014; 55(3):1222-30. APPENDICES – none SUPPORTING DATA – all figures including in body of report

  3. Verification of anti-fatigue effect of anserine by angle fatigue indicator based on median frequency changes of electromyograms

    Directory of Open Access Journals (Sweden)

    Hirohisa Kishi

    2013-10-01

    Full Text Available ABSTRACT: Objective: Anserine, which is abundant in avian species and in a wide range of fish such as bonito and tuna, is reported to have anti-fatigue effect. Although chicken soup and bonito soup is traditionally used to recover from physical fatigue, it is generally difficult to verify the effect in humans. This study was to directly demonstrate the anti-fatigue effect of oceanic anserine in humans. Methods: Edible-grade anserine was purified from fish extract with food-grade reagents. Subjects were 17 healthy male volunteers (35.5 ± 5 yr., 75.5 ± 5.0 kg. Each subject performed the isometric exercise tolerance test (ETT on the rectus femoris muscle twice (Ex_1, Ex_2 both for anserine and water conditions on a different day. Median frequency changes (MDF during Functional Foods in Health and Disease 2013; 3(10 389-399 ETTs were calculated and regression curves were calculated over a frequency range of 21-214 Hz. The difference, or angle, between the slopes of Ex_1 and Ex_2 MDF regression curves, which corresponds to the degree of fatigue, was defined as an angle fatigue index and compared between anserine and water intake conditions. Results: MDF decreased during ETTs in most patients and the slopes of regression curves were larger in Ex_2 than in Ex_1. Angle fatigue index for water (control was significantly larger than that for anserine (p<0.01, paired t-test, n=17. The result indicates that anserine have an anti-fatigue effect on skeletal muscle in humans. Conclusions: We proposed the angle fatigue index as a touchstone of the muscle fatigue. The index indicates that anserine is effective to reduce the muscle fatigue in humans.

  4. [Evaluation of the electromyography activity of pelvic floor muscle during postural exercises using the Wii Fit Plus©. Analysis and perspectives in rehabilitation].

    Science.gov (United States)

    Steenstrup, B; Giralte, F; Bakker, E; Grise, P

    2014-12-01

    The aim of this work was to evaluate the effect of postural awareness by using the Wii Fit Plus© on the quality of the baseline (automatic) activity of the pelvic floor muscles (PFM) measured by intravaginal surface electromyography (sEMG). Four healthy continent female subjects, all able to perform a voluntary contraction, undertook 2 sets of 3 various exercises offered by the software Wii Fit Plus© using the Wii balance board© (WBB): one set without any visual control and the second set with postural control and sEMG visual feedback. Simultaneously, we recorded the sEMG activity of the PFM. Mean baseline activity of PFM in standing position at start was 2.87 mV, at submaximal voluntary contraction the sEMG activity raised at a mean of 14.43 mV (7.87-21.89). In the first set of exercises on the WBB without any visual feedback, the automatic activity of the PFM increased from 2.87 mV to 8.75 mV (7.96-9.59). In the second set, with visual postural and sEMG control, mean baseline sEMG activity even raised at 11.39 mV (10.17-11.58). Among women able of a voluntary contraction of PFM, visualisation of posture with the help of the WBB and of sEMG activity of the PFM during static and dynamic Wii Fit Plus© activities, may improve the automatic activation of the PFMs. 4. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  5. Changes in motor unit behavior following isometric fatigue of the first dorsal interosseous muscle

    Science.gov (United States)

    Rymer, William Z.; Lowery, Madeleine M.; Suresh, Nina L.

    2015-01-01

    The neuromuscular strategies employed to compensate for fatigue-induced muscle force deficits are not clearly understood. This study utilizes surface electromyography (sEMG) together with recordings of a population of individual motor unit action potentials (MUAPs) to investigate potential compensatory alterations in motor unit (MU) behavior immediately following a sustained fatiguing contraction and after a recovery period. EMG activity was recorded during abduction of the first dorsal interosseous in 12 subjects at 20% maximum voluntary contraction (MVC), before and directly after a 30% MVC fatiguing contraction to task failure, with additional 20% MVC contractions following a 10-min rest. The amplitude, duration and mean firing rate (MFR) of MUAPs extracted with a sEMG decomposition system were analyzed, together with sEMG root-mean-square (RMS) amplitude and median frequency (MPF). MUAP duration and amplitude increased immediately postfatigue and were correlated with changes to sEMG MPF and RMS, respectively. After 10 min, MUAP duration and sEMG MPF recovered to prefatigue values but MUAP amplitude and sEMG RMS remained elevated. MU MFR and recruitment thresholds decreased postfatigue and recovered following rest. The increase in MUAP and sEMG amplitude likely reflects recruitment of larger MUs, while recruitment compression is an additional compensatory strategy directly postfatigue. Recovery of MU MFR in parallel with MUAP duration suggests a possible role for metabolically sensitive afferents in MFR depression postfatigue. This study provides insight into fatigue-induced neuromuscular changes by examining the properties of a large population of concurrently recorded single MUs and outlines possible compensatory strategies involving alterations in MU recruitment and MFR. PMID:25761952

  6. MYOELECTRIC ALTERATIONS AFTER VOLUNTARY INDUCED HIGH - AND LOW - FREQUENCY FATIGUE

    Directory of Open Access Journals (Sweden)

    Vojko Strojnik

    2008-06-01

    Full Text Available The aim of the study was to find whether voluntary induced high- and low-frequency peripheral fatigue exhibit specific alteration in surface EMG signal (SEMG during evoked and maximum voluntary contractions. Ten male students of physical education performed 60 s long stretch-shortening cycle (SSC exercise with maximal intensity and 30 s long concentric (CON exercise with maximal intensity. To verify voluntary induced peripheral fatigue, knee torques during low- (T20 and high-frequency electrical stimulation (T100 of relaxed vastus lateralis muscle (VL were obtained. Contractile properties of the VL were measured with passive twitch and maximal voluntary knee extension test (MVC. Changes in M-waves and SEMG during MVC test were used to evaluate the differences in myoelectrical signals. T100/T20 ratio decreased by 10.9 ± 8.4 % (p < 0.01 after the SSC exercise and increased by 35.9 ± 17.5 % (p < 0.001 after the CON exercise. Significant SEMG changes were observed only after the CON exercise where peak to peak time of the M-waves increased by 9.2 ± 13.3 % (p < 0.06, SEMG amplitude during MVC increased by 32.9 ± 21.6 % (p < 0.001 and SEMG power spectrum median frequency decreased by 11.0 ± 10.5 % (p < 0.05. It is concluded that high frequency fatigue wasn't reflected in SEMG, however the SEMG changes after the CON seemed to reflect metabolic changes due to acidosis

  7. Plastic Deformation of Metal Surfaces

    DEFF Research Database (Denmark)

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2013-01-01

    Plastic deformation of metal surfaces by sliding and abrasion between moving parts can be detrimental. However, when the plastic deformation is controlled for example by applying different peening techniques hard surfaces can be produced which can increase the fracture resistance and fatigue life...

  8. Surface Organization Influences Bistable Vision

    Science.gov (United States)

    Graf, Erich W.; Adams, Wendy J.

    2008-01-01

    A priority for the visual system is to construct 3-dimensional surfaces from visual primitives. Information is combined across individual cues to form a robust representation of the external world. Here, it is shown that surface completion relying on multiple visual cues influences relative dominance during binocular rivalry. The shape of a…

  9. Spanning quadrangulations of triangulated surfaces

    DEFF Research Database (Denmark)

    Kündgen, André; Thomassen, Carsten

    2017-01-01

    In this paper we study alternating cycles in graphs embedded in a surface. We observe that 4-vertex-colorability of a triangulation on a surface can be expressed in terms of spanninq quadrangulations, and we establish connections between spanning quadrangulations and cycles in the dual graph whic...

  10. Computational Complexity of Combinatorial Surfaces

    NARCIS (Netherlands)

    Vegter, Gert; Yap, Chee K.

    1990-01-01

    We investigate the computational problems associated with combinatorial surfaces. Specifically, we present an algorithm (based on the Brahana-Dehn-Heegaard approach) for transforming the polygonal schema of a closed triangulated surface into its canonical form in O(n log n) time, where n is the

  11. Friction of atomically stepped surfaces

    NARCIS (Netherlands)

    Dikken, R.J.; Thijsse, B.J.; Nicola, L.

    2017-01-01

    The friction behavior of atomically stepped metal surfaces under contact loading is studied using molecular dynamics simulations. While real rough metal surfaces involve roughness at multiple length scales, the focus of this paper is on understanding friction of the smallest scale of roughness:

  12. Luminescent Surface Quaternized Carbon Dots

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-10

    Thermal oxidation of a salt precursor made from the acid base combination of tris(hydroxymethyl)aminomethane and betaine hydrochloride results in light-emitting surface quaternized carbon dots that are water-dispersible, display anion exchange properties, and exhibit uniform size/surface charge. © 2011 American Chemical Society.

  13. Sculpturing Surfaces with Cartan Ribbons

    DEFF Research Database (Denmark)

    Raffaelli, Matteo; Bohr, Jakob; Markvorsen, Steen

    2016-01-01

    Using the concepts of Cartan development and rolling from differential geometry we develop a method for sculpturing any surface with the use of Cartan ribbons.......Using the concepts of Cartan development and rolling from differential geometry we develop a method for sculpturing any surface with the use of Cartan ribbons....

  14. Dilution of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Larsen, Torben; Petersen, Ole

    The purpose of present work is to establish a quantitative description of a surface plume which is valid for the range of density differences occurring in relation to sewage outfalls.......The purpose of present work is to establish a quantitative description of a surface plume which is valid for the range of density differences occurring in relation to sewage outfalls....

  15. A bag with soft surface

    International Nuclear Information System (INIS)

    Il-Tong Cheon.

    1991-02-01

    The MIT bag has a sharply edged surface. It seems to be unnatural. Taking vector mesons into account, we discuss effects of a smooth surface of the bag constructed by superposition of the MIT bags with various radii on the baryon magnetic moments. (author). 9 refs, 2 figs, 2 tabs

  16. Markov Random Field Surface Reconstruction

    DEFF Research Database (Denmark)

    Paulsen, Rasmus Reinhold; Bærentzen, Jakob Andreas; Larsen, Rasmus

    2010-01-01

    A method for implicit surface reconstruction is proposed. The novelty in this paper is the adaption of Markov Random Field regularization of a distance field. The Markov Random Field formulation allows us to integrate both knowledge about the type of surface we wish to reconstruct (the prior) and...

  17. Scanning Surface Potential Microscopy of Spore Adhesion on Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ida [University of Tennessee, Knoxville (UTK); Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

    2012-01-01

    The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica.

  18. Scanning surface potential microscopy of spore adhesion on surfaces.

    Science.gov (United States)

    Lee, I; Chung, E; Kweon, H; Yiacoumi, S; Tsouris, C

    2012-04-01

    The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Fog-harvesting Mesh Surfaces

    Science.gov (United States)

    Park, Kyoo-Chul; Chhatre, Shreerang S.; Srinivasan, Siddarth; Cohen, Robert E.; McKinley, Gareth H.

    2012-11-01

    Fog represents a large, untapped source of potable water, especially in arid climates. Various plants and animals use morphological as well as chemical features on their surfaces to harvest this precious resource. In this work, we investigate the influence of surface wettability, structural length scale, and relative openness of the weave on the fog harvesting ability of mesh surfaces. We choose simple woven meshes as a canonical family of model permeable surfaces due to the ability to systematically vary periodicity, porosity, mechanical robustness and ease of fabrication. We measure the fog collecting capacity of a set of meshes with a directed aqueous aerosol stream to simulate a natural foggy environment. Further, we strive to develop and test appropriate scalings and correlations that quantify the collection of water on the mesh surfaces. These design rules can be deployed as an a priori design chart for designing optimal performance meshes for given environmental/operating conditions.

  20. Surface states in photonic crystals

    Directory of Open Access Journals (Sweden)

    Vojtíšek P.

    2013-05-01

    Full Text Available Among many unusual and interesting physical properties of photonic crystals (PhC, in recent years, the propagation of surface electromagnetic waves along dielectric PhC boundaries have attracted considerable attention, also in connection to their possible applications. Such surfaces states, produced with the help of specialized defects on PhC boundaries, similarly to surfaces plasmons, are localized surfaces waves and, as such, can be used in various sensing applications. In this contribution, we present our recent studies on numerical modelling of surface states (SS for all three cases of PhC dimensionality. Simulations of these states were carried out by the use of plane wave expansion (PWE method via the MIT MPB package.