4,593 research outputs found

    Pattern effect reduction scheme for high-speed all-optical amplification system

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    A method for high-bit-rate optical pulse amplification without a pattern effect (PE) phenomenon is numerically analyzed and presented. In the proposed new scheme, the input signals are applied to a series of 1 × 2 optical switches and semiconductor optical amplifiers (SOAs). Based on the input signal bit rate and the desired PE reduction rate, it is shown that the number of these devices can be easily optimized. For reducing the SOA nonlinearities on the output signal, a high-birefringent fiber loop mirror is used as an optical Gaussian filter. The achieved results depict that symmetry and the time-bandwidth product of the output signal obtained by this filter are significantly improved. The simulations are performed for high bit-rate signals (> 50 Gbps); therefore, in the SOA model, all relevant nonlinear effects that occur in the subpicosecond regimes are taken into account. © 2014 Society of Photo-Optical Instrumentation Engineers

    Solution of Dual Fuzzy Equations Using a New Iterative Method

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    In this paper, a new hybrid scheme based on learning algorithm of fuzzy neural network (FNN) is offered in order to extract the approximate solution of fully fuzzy dual polynomials (FFDPs). Our FNN in this paper is a five-layer feed-back FNN with the identity activation function. The input-output relation of each unit is defined by the extension principle of Zadeh. The output from this neural network, which is also a fuzzy number, is numerically compared with the target output. The comparison of the feed-back FNN method with the feed-forward FNN method shows that the less error is observed in the feed-back FNN method. An example based on applications are given to illustrate the concepts, which are discussed in this paper

    Numerical evaluation of fractional Tricomi-type model arising from physical problems of gas dynamics

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    This paper deals with approximating the time fractional Tricomi-type model in the sense of the Caputo derivative. The model is often adopted for describing the anomalous process of nearly sonic speed gas dynamics. The temporal semi-discretization is computed via a finite difference algorithm, while the spatial discretization is obtained using the local radial basis function in a finite difference mode. The local collocation method approximates the differential operators using a weighted sum of the function values over a local collection of nodes (named stencil) through a radial basis function expansion. This technique considers merely the discretization nodes of each subdomain around the collocation node. This leads to sparse systems and tackles the ill-conditioning produced of global collocation. The theoretical convergence and stability analyses of the proposed time semi-discrete scheme are proved by means of the discrete energy method. Numerical results confirm the accuracy and efficiency of the new approach.The authors are very grateful to the reviewers for their valuable comments on the manuscript that led to many improvements.info:eu-repo/semantics/publishedVersio

    Attenuation of hemodynamic responses to laryngoscopy and tracheal intubation: Propacetamol versus lidocaine - A randomized clinical trial

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    The purpose of this study is to assess the effects of propacetamol on attenuating hemodynamic responses subsequent laryngoscopy and tracheal intubation compared to lidocaine. In this randomized clinical trial, 62 patients with the American Anesthesiologists Society (ASA) class I/II who required laryngoscopy and tracheal intubation for elective surgery were assigned to receive propacetamol 2 g/I.V./infusion (group P) or lidocaine 1.5 mg/kg (group L) prior to laryngoscopy. Systolic and diastolic blood pressures (SBP, DBP), mean arterial pressure (MAP), and heart rate (HR) were recorded at baseline, before laryngoscopy and within nine minutes after intubation. In both groups P and L, MAP increased after laryngoscopy and the changes were statistically significant (P < 0.001). There were significant changes of HR in both groups after intubation (P < 0.02), but the trend of changes was different between two groups (P < 0.001). In group L, HR increased after intubation and its change was statistically significant within 9 minutes after intubation (P < 0.001), while in group P, HR remained stable after intubation (P = 0.8). Propacetamol 2 gr one hour prior intubation attenuates heart rate responses after laryngoscopy but is not effective to prevent acute alterations in blood pressure after intubation. © 2014 Ali Kord Valeshabad et al

    Controlling surface statistical properties using bias voltage: Atomic force microscopy and stochastic analysis

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    The effect of bias voltages on the statistical properties of rough surfaces has been studied using atomic force microscopy technique and its stochastic analysis. We have characterized the complexity of the height fluctuation of a rough surface by the stochastic parameters such as roughness exponent, level crossing, and drift and diffusion coefficients as a function of the applied bias voltage. It is shown that these statistical as well as microstructural parameters can also explain the macroscopic property of a surface. Furthermore, the tip convolution effect on the stochastic parameters has been examined.Comment: 8 pages, 11 figures

    Long-range correlation and multifractality in Bach's Inventions pitches

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    We show that it can be considered some of Bach pitches series as a stochastic process with scaling behavior. Using multifractal deterend fluctuation analysis (MF-DFA) method, frequency series of Bach pitches have been analyzed. In this view we find same second moment exponents (after double profiling) in ranges (1.7-1.8) in his works. Comparing MF-DFA results of original series to those for shuffled and surrogate series we can distinguish multifractality due to long-range correlations and a broad probability density function. Finally we determine the scaling exponents and singularity spectrum. We conclude fat tail has more effect in its multifractality nature than long-range correlations.Comment: 18 page, 6 figures, to appear in JSTA

    A Qualitative and Quantitative Analysis of Protein Substitution in Human Burn Wounds

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    Objective: In major burn wounds of more than 15% total burn surface area mediator-associated reactions lead to capillary leak resulting in critical condition. Little is known about the efficiency of protein substitution. We quantified and qualified the systemic and local protein loss in burn patients during protein substitution, comparing fresh frozen plasma and the human serum protein solution Biseko. Methods: In 40 patients suffering from second-degree burn wounds with the total burn surface area between 20% and 60%, immediately after admission a defined wound surface area was enclosed with in a wound chamber. Wound fluid and serum samples were collected in 8 hour intervals for 2 days. Samples were analyzed for total protein, albumin, immunoglobulins -A, -G, -M, clotting parameters, c-reactive protein, and white blood cells. Protein substitution started 24 hour posttrauma. In a randomized pattern, patients received equal volumes of fresh frozen plasma or Biseko. Results: Total protein and albumin accumulated in high concentrations in wound fluid. With beginning of fresh frozen plasma substitution on day 2 posttrauma, serum total protein (1.7 g–3.9 g) and albumin (1.3 g–3.4 g) concentrations increased. Substitution of Biseko resulted in a stronger increase (serum total protein 1.8 g to 4.5 g, albumin 0.9 g to 3.4 g). Wound fluid concentrations revealed similar change patterns. Immunoglobulins showed higher serum levels in the Biseko group. C-reactive protein and white blood cell values indicated a lower immunological reaction in the Biseko group. Conclusions: Substitution of human protein solutions such as Biseko can result in significantly higher serum protein and albumin concentrations as well as lower infection parameters. Higher serum immunoglobulins could help to decrease potential immunodeficiency
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