Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 27 (1989), S. 538-542 
    ISSN: 1741-0444
    Keywords: Electrogastrography ; Gastric activity ; Phase shift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Electrogastric signals have been successfully measured both intraluminally and cutaneously. although it has been claimed by several researchers that the propagation direction of the electrogastric activities cannot be observed from cutaneous recordings, it is the aim of the paper to show that it is feasible. The reason why the propagation direction has never been observed from cutaneous recordings is that the reported methods for the abdominal measurements are not adequate. In the paper it is pointed out that the stomach should be localised before the measurement and the electrodes should be attached along the longitudinal axis of the stomach.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 29 (1991), S. 339-350 
    ISSN: 1741-0444
    Keywords: Bio-potential ; Electrogastrography ; Gastric motility ; Myoelectrical activity ; Signal analysis ; Slow wave ; Stomach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Electrogastrography (EGG), the cutaneous recording of the myoelectrical activity of the stomach using surface electrodes, is attractive due to its non-invasiveness and its correlation with gastric motility. Since the first measurement of the EGG, a great deal of research effort has been expended on investigating its relationship with specific activities of the stomach in question. In this review, we discuss how to measure the EGG, what information is available in the EGG, how to extract useful information from the EGG and the prospective applications of the EGG. After a brief historic evolution of the EGG, we first discuss the measurement of the EGG, the importance of localisation of the stomach and the characteristics of the EGG. The most commonly used EGG data-analysis methods, both power spectral analysis and waveform analysis, are then outlined. Some of prospective applications of the EGG in clinical diagnosis and medical research are described, mainly concerning the correlation between EGG amplitude and gastric motility and that between EGG rhythmic variations and motility disorders. Specifically, we present studies on pre- and postprandial EGGs, observation of the propagation direction of the gastric slow wave and gastric electrical dysrhythmias and their correlation with gastric motility.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 28 (1990), S. 531-536 
    ISSN: 1741-0444
    Keywords: Autoregressive moving average modelling ; Electrogastrography ; Gastric motility ; Gastric slow wave ; Spectral analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The recording of the human, gastric myoelectrical activity, by means of cutaneous electrodes is called electrogastrography (EGG). It provides a noninvasive method of studying electrogastric behaviour. The normal frequency of the gastric signal is about 0·05 Hz. However, sudden changes of its frequency have been observed and are generally considered to be related to gastric motility disorders. Thus, spectral analysis, especially online spectral analysis, can serve as a valuable tool for practical purposes. The paper presents a new method of the adaptive spectral analysis of cutaneous electrogastric signals using autoregressive moving average (ARMA) modelling. It is based on an adaptive ARMA filter and provides both time and frequency information of the signal. Its performance is investigated in comparison with the conventional FFT-based periodogram method. Its properties in tracking time-varying instantaneous frequencies are shown. Its applications to the running spectral analysis of cutaneous electrogastric signals are presented. The proposed adaptive ARMA spectral analysis method is easy to implement and is efficient in computations. The results presented in the paper show that this new method provides a better performance and is very useful for the online monitoring of cutaneous electrogastric signals.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 26 (1998), S. 859-869 
    ISSN: 1573-9686
    Keywords: Spectral analysis ; Matching pursuit ; Stomach ; Gastric motility ; Electrogastrography ; Evolutionary programming ; Signal analysis ; Electrogastrogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The electrogastrogram (EGG) is a surface measurement of gastric myoelectrical activity. The normal frequency of gastric myoelectrical activity in humans is 3 cycles/min. Abnormal frequencies in gastric myoelectrical activity have been found to be associated with functional disorders of the stomach. The aim of this article was, therefore, to develop new time-frequency analysis methods for the detection of gastric dysrhythmia from the EGG. A concept of overcomplete signal representation was used. Two algorithms were proposed for the optimization of the overcomplete signal representation. One was a fast algorithm of matching pursuit and the other was based on an evolutionary program. Computer simulations were performed to compare the performance of the proposed methods in comparison with existing time-frequency analysis methods. It was found that the proposed algorithms provide higher frequency resolution than the short time Fourier transform and Wigner-Ville distribution methods. The practical application of the developed methods to the EGG is also presented. It was concluded that these methods are well suited for the time-frequency analysis of the EGG and may also be applicable to the time-frequency analysis of other biomedical signals. © 1998 Biomedical Engineering Society. PAC98: 8780+s, 0705Kf
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 27 (1999), S. 88-95 
    ISSN: 1573-9686
    Keywords: Electrogastrography ; Gastric motility ; Stomach ; Filter banks ; Neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Dysrhythmia in gastric myoelectrical activity has been frequently observed in patients with gastric motor disorders and gastrointestinal symptoms. The assessment of the regularity of gastric myoelectrical activity is of great clinical significance. The aim of this study was to develop an automated assessment method for the regularity of gastric myoelectrical activity from the surface electrogastrogram (EGG). The method proposed in this paper was based on the filter bank and neural network. First, the EGG signal was divided into frequency subbands using filter bank analysis. Second, a parameter called the subband energy ratio (SER) was computed for each subband signal. A multilayer perceptron neural network was then used to automatically classify the EGG signal into four categories: bradygastria, normal, tachygastria, and arrhythmia, using the SER as the input. The EGG recording was made using the standard method of electrogastrography by placing electrodes on the abdominal surface. The study was performed in 40 patients with various gastric motor disorders, ten healthy adults, and ten healthy children. The neural network was trained and tested using the EGG data obtained from the patients. The regularity of gastric myoelectrical activity was assessed based on the classification of the minute-by-minute EGG segments. Using the running spectral analysis method as a gold standard, the proposed automated method had an accuracy of 100% for the training set and 97% for the test set. It was concluded that the proposed method provides an accurate and automatic assessment of the regularity of gastric myoelectrical activity from the EGG. © 1999 Biomedical Engineering Society. PAC99: 8780-y, 8717-d, 0705Mh, 0270Hm
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 31 (1993), S. 60-67 
    ISSN: 1741-0444
    Keywords: Electrogastrogram ; Electrogastrography ; Gastric motility ; Intestinal motility ; Myoelectrical activity ; Spectral analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 21 (1995), S. 129-139 
    ISSN: 0271-2091
    Keywords: numerical technique ; boundary layer equations ; reacting flow ; full coupling ; finite rate chemistry effects ; thermal radiation effects ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new numerical scheme for reacting axisymmetric jet flows formed between a fuel jet and co-flowing air has been developed. The model is mathematically described by a set of non-linear parabolic partial differential equations in two space dimensions, i.e. the boundary layer equations. The numerical scheme that the programme uses for solving the fully coupled conservation equations of mass, momentum, energy and species is a generaliztion of the discretization technique recently developed by Villasenor (J. Math. Comput. Simul., 36, 203-208 (1994)). Chemical production (and destruction) of the species is allowed to occur through N elementary reversible (or irreversible) reactions involving k species, although in the present model the reaction rates are evaluated with a simplified kinetic mechanism for a one-step global reaction. Thermal radiation is considered assuming an optically thin limit and adopting the grey medium approximation. Allowances are made for natural convection effects and variable thermodynamic and molecular transport properties. The performance of the model in solving the coupled aerodynamic and finite rate chemistry effects is tested by comparing model predictions with experimental data of Mitchell et al. (Combust. Flame, 37, 227-244 (1980)) for a buoyant, laminar, diffusion axisymmetric methane-air flame.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 23 (1986), S. 831-846 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: As an effort to predict effectively the actual collapse load of a structure, a series of numerical studies on the stability of shell structures are made. The difference in formulation between the two types of linear buckling loads, the classical and the fully linearized, is first demonstrated. Their correlations with respect to the actual stability limit of the structure are compared, and finally the two types of critical load approximations are obtained at various stages of a nonlinear analysis to study the pattern of convergence to the actual collapse load. It is found that the fully linearized buckling analysis, when combined with nonlinear analysis, can serve as a useful tool for prediction of the stability limit of a structure. While for most types of structures the approximation is within engineering accuracy, the rate of convergence of the extrapolated critical load also gives some insight to the accuracy of the approximation.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 847-865 
    ISSN: 0029-5981
    Keywords: interlaminar shear stress ; layer reduction technique ; composite laminate ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Interlaminar stress plays an important role in the delamination failure of laminated composites. A recently presented theory, the Interlaminar Shear Stress Continuity Theory (ISSCT), can directly and accurately predict interlaminar shear stresses in laminated composites by the constitutive equations. The present study further generalizes the derivation to a complete form from which many displacement-based laminate theories can be derived. Most of all, both the single-layer and multiple-layer approaches are incorporated into the analysis in the thickness direction. The laminate is discretized into several sublaminates and, then, a layerwise theory is applied in the analysis of this reduced laminate. This reduction in the number of layers used in the analysis makes the calculation of interlaminar shear stresses on the interested interface in a thick laminate more efficient. In addition, numerical solutions in closed-form and finite element form for laminates under cylindrical bending and bidirectional bending are examined. It is found that in the thickness direction the cubic order of the interpolation function and the discretization with four to six sublaminates can reduce the computational efforts dramatically and retain the accuracy of the predicted stresses within ±8 per cent.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 479-490 
    ISSN: 1069-8299
    Keywords: Modal reaction method ; modal participation factor ; support motion ; discrete system ; modal equivalent mass ; quasi-static decomposition ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An efficient method, called the modal reaction method, for calculating the modal participation factors for support motion problems is proposed. It is found that modal reactions at supports proportionally describe the magnitudes of the modal participation factors. Thus, the modal participation factor for support motion problems can be calculated very efficiently, saving more than 99 per cent, for the given example with 640 degreees of freedom, of the CPU time compared with using the popular quasistatic decomposition method.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...