A Nonlinear Approach to Tunisian Inflation Rate
Directory of Open Access Journals (Sweden)
Thouraya Boujelbène Dammak
2016-09-01
Full Text Available In this study, we investigated the properties and the macroeconomic performance of the nonlinearity of the Inflation Rate Set in Tunisia. We developed an inference asymptotic theory for an unrestricted two-regime threshold autoregressive (TAR model with an autoregressive unit root. We proposed two types of tests namely asymptotic and bootstrap-based. These tests as well as the distribution theory allow a joint consideration of nonlinear thresholds and non-stationary unit roots. Our empirical results reveal a strong evidence of a threshold effect. This makes clear the possibility of non stationary and nonlinear of the Monthly Inflation Rate in Tunisia for the 1994.01-2011.06 period. While the Perron test found a unit root, our TAR unit root tests are arguably significant. Then, the evidence is quite strong that the inflation rate is not a unit root process.
Central Limit Theorem for Nonlinear Hawkes Processes
Zhu, Lingjiong
2012-01-01
Hawkes process is a self-exciting point process with clustering effect whose jump rate depends on its entire past history. It has wide applications in neuroscience, finance and many other fields. Linear Hawkes process has an immigration-birth representation and can be computed more or less explicitly. It has been extensively studied in the past and the limit theorems are well understood. On the contrary, nonlinear Hawkes process lacks the immigration-birth representation and is much harder to analyze. In this paper, we obtain a functional central limit theorem for nonlinear Hawkes process.
CMOS Nonlinear Signal Processing Circuits
2010-01-01
The chapter describes various nonlinear signal processing CMOS circuits, including a high reliable WTA/LTA, simple MED cell, and low-voltage arbitrary order extractor. We focus the discussion on CMOS analog circuit design with reliable, programmable capability, and low voltage operation. It is a practical problem when the multiple identical cells are required to match and realized within a single chip using a conventional process. Thus, the design of high-reliable circuit is indeed needed. Th...
The Nonlinear Spatial Damping Rate in QGP
Jiarong, L
1998-01-01
The derivative expansion method has been used to solve the semiclassical kinetic equations of quark-gluon plasma (QGP). The nonlinear spatial damping rate, the imaginary part of the wave vector, for the longitudinal secondary color waves in the long wavelength limit has been calculated numerically.
Internal Decoupling in Nonlinear Process Control
Directory of Open Access Journals (Sweden)
Jens G. Balchen
1988-07-01
Full Text Available A simple method has been investigated for the total or partial removal of the effect of non-linear process phenomena in multi-variable feedback control systems. The method is based upon computing the control variables which will drive the process at desired rates. It is shown that the effect of model errors in the linearization of the process can be partly removed through the use of large feedback gains. In practice there will be limits on how large gains can he used. The sensitivity to parameter errors is less pronounced and the transient behaviour is superior to that of ordinary PI controllers.
Nonlinear filtering for LIDAR signal processing
Directory of Open Access Journals (Sweden)
D. G. Lainiotis
1996-01-01
Full Text Available LIDAR (Laser Integrated Radar is an engineering problem of great practical importance in environmental monitoring sciences. Signal processing for LIDAR applications involves highly nonlinear models and consequently nonlinear filtering. Optimal nonlinear filters, however, are practically unrealizable. In this paper, the Lainiotis's multi-model partitioning methodology and the related approximate but effective nonlinear filtering algorithms are reviewed and applied to LIDAR signal processing. Extensive simulation and performance evaluation of the multi-model partitioning approach and its application to LIDAR signal processing shows that the nonlinear partitioning methods are very effective and significantly superior to the nonlinear extended Kalman filter (EKF, which has been the standard nonlinear filter in past engineering applications.
Institute of Scientific and Technical Information of China (English)
胡业民; 胡希伟
2001-01-01
Numerical analyses for the nonlinear evolutions of stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) processes are given. Various effects of the second- and third-order nonlinear susceptibilities on the SRS and SBS processes are studied. The nonlinear evolutions of SRS and SBS processes are atfected more efficiently than their linear growth rates by the nonlinear susceptibility.
Multiorder nonlinear diffraction in frequency doubling processes
DEFF Research Database (Denmark)
Saltiel, Solomon M.; Neshev, Dragomir N.; Krolikowski, Wieslaw
2009-01-01
We analyze experimentally light scattering from 2 nonlinear gratings and observe two types of second-harmonic frequency-scattering processes. The first process is identified as Raman–Nath type nonlinear diffraction that is explained by applying only transverse phase-matching conditions. The angular...... position of this type of diffraction is defined by the ratio of the second-harmonic wavelength and the grating period. In contrast, the second type of nonlinear scattering process is explained by the longitudinal phase matching only, being insensitive to the nonlinear grating...
Digital signal processing for fiber nonlinearities [Invited
DEFF Research Database (Denmark)
Cartledge, John C.; Guiomar, Fernando P.; Kschischang, Frank R.
2017-01-01
This paper reviews digital signal processing techniques that compensate, mitigate, and exploit fiber nonlinearities in coherent optical fiber transmission systems......This paper reviews digital signal processing techniques that compensate, mitigate, and exploit fiber nonlinearities in coherent optical fiber transmission systems...
Input saturation in nonlinear multivariable processes resolved by nonlinear decoupling
Directory of Open Access Journals (Sweden)
Jens G. Balchen
1995-04-01
Full Text Available A new method is presented for the resolution of the problem of input saturation in nonlinear multivariable process control by means of elementary nonlinear decoupling (END. Input saturation can have serious consequences particularly in multivariable control because it may lead to very undesirable system behaviour and quite often system instability. Many authors have searched for systematic techniques for designing multivariable control systems in which saturation may occur in any of the control variables (inputs, manipulated variables. No generally accepted method seems to have been presented so far which gives a solution in closed form. The method of elementary nonlinear decoupling (END can be applied directly to the case of saturation control variables by deriving as many control strategies as there are combinations of saturating control variables. The method is demonstrated by the multivariable control of a simulated Fluidized Catalytic Cracker (FCC with very convincing results.
Sensor Network Design for Nonlinear Processes
Institute of Scientific and Technical Information of China (English)
李博; 陈丙珍
2003-01-01
This paper presents a method to design a cost-optimal nonredundant sensor network to observe all variables in a general nonlinear process. A mixed integer linear programming model was used to minimize the cost with data classification to check the observability of all unmeasured variables. This work is a starting point for designing sensor networks for general nonlinear processes based on various criteria, such as reliability and accuracy.
Broadband Nonlinear Signal Processing in Silicon Nanowires
DEFF Research Database (Denmark)
Yvind, Kresten; Pu, Minhao; Hvam, Jørn Märcher;
The fast non-linearity of silicon allows Tbit/s optical signal processing. By choosing suitable dimensions of silicon nanowires their dispersion can be tailored to ensure a high nonlinearity at power levels low enough to avoid significant two-photon abso We have fabricated low insertion and propa......The fast non-linearity of silicon allows Tbit/s optical signal processing. By choosing suitable dimensions of silicon nanowires their dispersion can be tailored to ensure a high nonlinearity at power levels low enough to avoid significant two-photon abso We have fabricated low insertion...... and propagation loss silicon nanowires and use them to demonstrate the broadband capabilities of silicon....
The maximal process of nonlinear shot noise
Eliazar, Iddo; Klafter, Joseph
2009-05-01
In the nonlinear shot noise system-model shots’ statistics are governed by general Poisson processes, and shots’ decay-dynamics are governed by general nonlinear differential equations. In this research we consider a nonlinear shot noise system and explore the process tracking, along time, the system’s maximal shot magnitude. This ‘maximal process’ is a stationary Markov process following a decay-surge evolution; it is highly robust, and it is capable of displaying both a wide spectrum of statistical behaviors and a rich variety of random decay-surge sample-path trajectories. A comprehensive analysis of the maximal process is conducted, including its Markovian structure, its decay-surge structure, and its correlation structure. All results are obtained analytically and in closed-form.
Ultrafast Nonlinear Signal Processing in Silicon Waveguides
DEFF Research Database (Denmark)
Oxenløwe, Leif Katsuo; Mulvad, Hans Christian Hansen; Hu, Hao;
2012-01-01
We describe recent demonstrations of exploiting highly nonlinear silicon waveguides for ultrafast optical signal processing. We describe wavelength conversion and serial-to-parallel conversion of 640 Gbit/s data signals and 1.28 Tbit/s demultiplexing and all-optical sampling.......We describe recent demonstrations of exploiting highly nonlinear silicon waveguides for ultrafast optical signal processing. We describe wavelength conversion and serial-to-parallel conversion of 640 Gbit/s data signals and 1.28 Tbit/s demultiplexing and all-optical sampling....
Recent advances in nonlinear speech processing
Faundez-Zanuy, Marcos; Esposito, Antonietta; Cordasco, Gennaro; Drugman, Thomas; Solé-Casals, Jordi; Morabito, Francesco
2016-01-01
This book presents recent advances in nonlinear speech processing beyond nonlinear techniques. It shows that it exploits heuristic and psychological models of human interaction in order to succeed in the implementations of socially believable VUIs and applications for human health and psychological support. The book takes into account the multifunctional role of speech and what is “outside of the box” (see Björn Schuller’s foreword). To this aim, the book is organized in 6 sections, each collecting a small number of short chapters reporting advances “inside” and “outside” themes related to nonlinear speech research. The themes emphasize theoretical and practical issues for modelling socially believable speech interfaces, ranging from efforts to capture the nature of sound changes in linguistic contexts and the timing nature of speech; labors to identify and detect speech features that help in the diagnosis of psychological and neuronal disease, attempts to improve the effectiveness and performa...
Quantum Information Processing using Nonlinear Optical Effects
DEFF Research Database (Denmark)
Andersen, Lasse Mejling
of the converted idler depends on the other pump. This allows for temporal-mode-multiplexing. When the effects of nonlinear phase modulation (NPM) are included, the phases of the natural input and output modes are changed, reducing the separability. These effects are to some degree mediated by pre......This PhD thesis treats applications of nonlinear optical effects for quantum information processing. The two main applications are four-wave mixing in the form of Bragg scattering (BS) for quantum-state-preserving frequency conversion, and sum-frequency generation (SFG) in second-order nonlinear...... to obtain a 100 % conversion efficiency is to use multiple stages of frequency conversion, but this setup suffers from the combined effects of NPM. This problem is circumvented by using asymmetrically pumped BS, where one pump is continuous wave. For this setup, NPM is found to only lead to linear phase...
Nonlinearity degree of short-term heart rate variability signal
Institute of Scientific and Technical Information of China (English)
BIAN Chunhua; NING Xinbao
2004-01-01
A nonlinear autoregressive (NAR) model is built to model the heartbeat interval time series and the optimum model degree is proposed to be taken to evaluate the nonlinearity degree of heart rate variability (HRV). A group of healthy persons are studied and the results indicate that this method can effectively get nonlinear information from short (6-7 min) heartbeat series and consequently reflect the degree of heart rate variability, which supplies convenience in clinical application. Finally, a comparison with the traditional time domain method shows that the NAR model method can reflect the complexity of the whole signal and lessen the influence of noise and instability in the signal.
Processing Approach of Non-linear Adjustment Models in the Space of Non-linear Models
Institute of Scientific and Technical Information of China (English)
LI Chaokui; ZHU Qing; SONG Chengfang
2003-01-01
This paper investigates the mathematic features of non-linear models and discusses the processing way of non-linear factors which contributes to the non-linearity of a nonlinear model. On the basis of the error definition, this paper puts forward a new adjustment criterion, SGPE.Last, this paper investigates the solution of a non-linear regression model in the non-linear model space and makes the comparison between the estimated values in non-linear model space and those in linear model space.
Nonlinearly perturbed semi-Markov processes
Silvestrov, Dmitrii
2017-01-01
The book presents new methods of asymptotic analysis for nonlinearly perturbed semi-Markov processes with a finite phase space. These methods are based on special time-space screening procedures for sequential phase space reduction of semi-Markov processes combined with the systematical use of operational calculus for Laurent asymptotic expansions. Effective recurrent algorithms are composed for getting asymptotic expansions, without and with explicit upper bounds for remainders, for power moments of hitting times, stationary and conditional quasi-stationary distributions for nonlinearly perturbed semi-Markov processes. These results are illustrated by asymptotic expansions for birth-death-type semi-Markov processes, which play an important role in various applications. The book will be a useful contribution to the continuing intensive studies in the area. It is an essential reference for theoretical and applied researchers in the field of stochastic processes and their applications that will cont...
Nonlinear Process Fault Diagnosis Based on Serial Principal Component Analysis.
Deng, Xiaogang; Tian, Xuemin; Chen, Sheng; Harris, Chris J
2016-12-22
Many industrial processes contain both linear and nonlinear parts, and kernel principal component analysis (KPCA), widely used in nonlinear process monitoring, may not offer the most effective means for dealing with these nonlinear processes. This paper proposes a new hybrid linear-nonlinear statistical modeling approach for nonlinear process monitoring by closely integrating linear principal component analysis (PCA) and nonlinear KPCA using a serial model structure, which we refer to as serial PCA (SPCA). Specifically, PCA is first applied to extract PCs as linear features, and to decompose the data into the PC subspace and residual subspace (RS). Then, KPCA is performed in the RS to extract the nonlinear PCs as nonlinear features. Two monitoring statistics are constructed for fault detection, based on both the linear and nonlinear features extracted by the proposed SPCA. To effectively perform fault identification after a fault is detected, an SPCA similarity factor method is built for fault recognition, which fuses both the linear and nonlinear features. Unlike PCA and KPCA, the proposed method takes into account both linear and nonlinear PCs simultaneously, and therefore, it can better exploit the underlying process's structure to enhance fault diagnosis performance. Two case studies involving a simulated nonlinear process and the benchmark Tennessee Eastman process demonstrate that the proposed SPCA approach is more effective than the existing state-of-the-art approach based on KPCA alone, in terms of nonlinear process fault detection and identification.
Nonlinear Control of Heart Rate Variability in Human Infants
Sugihara, George; Allan, Walter; Sobel, Daniel; Allan, Kenneth D.
1996-03-01
Nonlinear analyses of infant heart rhythms reveal a marked rise in the complexity of the electrocardiogram with maturation. We find that normal mature infants (gestation >= 35 weeks) have complex and distinctly nonlinear heart rhythms (consistent with recent reports for healthy adults) but that such nonlinearity is lacking in preterm infants (gestation parasympathetic-sympathetic interaction and function are presumed to be less well developed. Our study further shows that infants with clinical brain death and those treated with atropine exhibit a similar lack of nonlinear feedback control. These three lines of evidence support the hypothesis championed by Goldberger et al. [Goldberger, A. L., Rigney, D. R. & West, B. J. (1990) Sci. Am. 262, 43-49] that autonomic nervous system control underlies the nonlinearity and possible chaos of normal heart rhythms. This report demonstrates the acquisition of nonlinear heart rate dynamics and possible chaos in developing human infants and its loss in brain death and with the administration of atropine. It parallels earlier work documenting changes in the variability of heart rhythms in each of these cases and suggests that nonlinearity may provide additional power in characterizing physiological states.
Information mining in weighted complex networks with nonlinear rating projection
Liao, Hao; Zeng, An; Zhou, Mingyang; Mao, Rui; Wang, Bing-Hong
2017-10-01
Weighted rating networks are commonly used by e-commerce providers nowadays. In order to generate an objective ranking of online items' quality according to users' ratings, many sophisticated algorithms have been proposed in the complex networks domain. In this paper, instead of proposing new algorithms we focus on a more fundamental problem: the nonlinear rating projection. The basic idea is that even though the rating values given by users are linearly separated, the real preference of users to items between the different given values is nonlinear. We thus design an approach to project the original ratings of users to more representative values. This approach can be regarded as a data pretreatment method. Simulation in both artificial and real networks shows that the performance of the ranking algorithms can be improved when the projected ratings are used.
A non-linear model of economic production processes
Ponzi, A.; Yasutomi, A.; Kaneko, K.
2003-06-01
We present a new two phase model of economic production processes which is a non-linear dynamical version of von Neumann's neoclassical model of production, including a market price-setting phase as well as a production phase. The rate of an economic production process is observed, for the first time, to depend on the minimum of its input supplies. This creates highly non-linear supply and demand dynamics. By numerical simulation, production networks are shown to become unstable when the ratio of different products to total processes increases. This provides some insight into observed stability of competitive capitalist economies in comparison to monopolistic economies. Capitalist economies are also shown to have low unemployment.
Nonlinear Markov Control Processes and Games
2012-11-15
further research we indicated possible extensions to state spaces with nontrivial geometry, to the controlled nonlinear quantum dynamic semigroups and...space nonlinear Markov semigroup is a one-parameter semigroup of (possibly nonlinear) transformations of the unit simplex in n-dimensional Euclidean...certain mixing property of nonlinear transition probabilities. In case of the semigroup parametrized by continuous time one defines its generator as the
Nonlinear biochemical signal processing via noise propagation.
Kim, Kyung Hyuk; Qian, Hong; Sauro, Herbert M
2013-10-14
Single-cell studies often show significant phenotypic variability due to the stochastic nature of intra-cellular biochemical reactions. When the numbers of molecules, e.g., transcription factors and regulatory enzymes, are in low abundance, fluctuations in biochemical activities become significant and such "noise" can propagate through regulatory cascades in terms of biochemical reaction networks. Here we develop an intuitive, yet fully quantitative method for analyzing how noise affects cellular phenotypes based on identifying a system's nonlinearities and noise propagations. We observe that such noise can simultaneously enhance sensitivities in one behavioral region while reducing sensitivities in another. Employing this novel phenomenon we designed three biochemical signal processing modules: (a) A gene regulatory network that acts as a concentration detector with both enhanced amplitude and sensitivity. (b) A non-cooperative positive feedback system, with a graded dose-response in the deterministic case, that serves as a bistable switch due to noise-induced ultra-sensitivity. (c) A noise-induced linear amplifier for gene regulation that requires no feedback. The methods developed in the present work allow one to understand and engineer nonlinear biochemical signal processors based on fluctuation-induced phenotypes.
Recombination Processes and Nonlinear Markov Chains.
Pirogov, Sergey; Rybko, Alexander; Kalinina, Anastasia; Gelfand, Mikhail
2016-09-01
Bacteria are known to exchange genetic information by horizontal gene transfer. Since the frequency of homologous recombination depends on the similarity between the recombining segments, several studies examined whether this could lead to the emergence of subspecies. Most of them simulated fixed-size Wright-Fisher populations, in which the genetic drift should be taken into account. Here, we use nonlinear Markov processes to describe a bacterial population evolving under mutation and recombination. We consider a population structure as a probability measure on the space of genomes. This approach implies the infinite population size limit, and thus, the genetic drift is not assumed. We prove that under these conditions, the emergence of subspecies is impossible.
Global satisfactory control for nonlinear integrator processes with long delay
Institute of Scientific and Technical Information of China (English)
Yiqun YANG; Guobo XIANG
2007-01-01
Integrator processes with long delay are difficult to control. Nonlinear characteristics of actuators make the control problem more challenging. A technique is proposed in this paper for global satisfactory control (GSC) of such processes with relay-type nonlinearity. An oscillatory control signal is injected into the nonlinear process; the amplitude and frequency of the oscillatory signal are designed to linearise the nonlinear process in the sense of harmonic analysis; and a state feedback controller is configured to implement GSC over the linearised process. An illustrative example is given to demonstrate the effectiveness of the proposed method.
Nonlinearity and fractional integration in the US dollar/euro exchange rate
Directory of Open Access Journals (Sweden)
Kiran Burcu
2012-01-01
Full Text Available This paper examines the nonlinear behavior and the fractional integration property of the US dollar/euro exchange rate over the period from January 1999 to August 2010 by extending the procedure of Peter M. Robinson (1994 to the case of nonlinearity. First, using the approach developed by Mehmet Caner and Bruce E. Hansen (2001, we investigate the possible presence of nonlinearity in the series through the estimation of a two-regime threshold autoregressive model. After finding nonlinearity, we also allow for disturbances to be fractionally integrated based on the different versions of Robinson (1994 tests. The findings show that the US dollar/euro exchange rate follows a stationary process with a weak evidence for long memory.
Experimental characterization of nonlinear processes of whistler branch waves
Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Ganguli, G.; Rudakov, L.
2016-05-01
Experiments in the Space Physics Simulation Chamber at the Naval Research Laboratory isolated and characterized important nonlinear wave-wave and wave-particle interactions that can occur in the Earth's Van Allen radiation belts by launching predominantly electrostatic waves in the intermediate frequency range with wave normal angle greater than 85 ° and measuring the nonlinearly generated electromagnetic scattered waves. The scattered waves have a perpendicular wavelength that is nearly an order of magnitude larger than that of the pump wave. Calculations of scattering efficiency from experimental measurements demonstrate that the scattering efficiency is inversely proportional to the damping rate and trends towards unity as the damping rate approaches zero. Signatures of both wave-wave and wave-particle scatterings are also observed in the triggered emission process in which a launched wave resonant with a counter-propagating electron beam generates a large amplitude chirped whistler wave. The possibility of nonlinear scattering or three wave decay as a saturation mechanism for the triggered emission is suggested. The laboratory experiment has inspired the search for scattering signatures in the in situ data of chorus emission in the radiation belts.
The Nonlinear Landau Damping Rate of a Driven Plasma Wave
Energy Technology Data Exchange (ETDEWEB)
Benisti, D; Strozzi, D J; Gremillet, L; Morice, O
2009-08-04
In this Letter, we discuss the concept of the nonlinear Landau damping rate, {nu}, of a driven electron plasma wave, and provide a very simple, practical, analytic formula for {nu} which agrees very well with results inferred from Vlasov simulations of stimulated Raman scattering. {nu} actually is more complicated an operator than a plain damping rate, and it may only be seen as such because it assumes almost constant values before abruptly dropping to 0. The decrease of {nu} to 0 is moreover shown to occur later when the wave amplitude varies in the direction transverse to its propagation.
Lp-decay rates to nonlinear diffusion waves for p-system with nonlinear damping
Institute of Scientific and Technical Information of China (English)
ZHU Changjiang; JIANG Mina
2006-01-01
In this paper, we study the Lp (2 ≤ p ≤ +∞) convergence rates of the solutions to the Cauchy problem of the so-called p-system with nonlinear damping. Precisely, we show that the corresponding Cauchy problem admits a unique global solution (v(x,t),u(x,t)) and such a solution tends time-asymptotically to the corresponding nonlinear diffusion wave (-v(x, t), -u(x, t)) governed by the classical Darcy's law provided that the corresponding prescribed initial error function (w0(x), z0(x))lies in (H3 × H2) (R) and |v+ - v-| + ‖w0‖3 + ‖z0‖2 is sufficiently small.Furthermore, the Lp (2 ≤ p ≤ +∞) convergence rates of the solutions are also obtained.
Generalized Mass Action Law and Thermodynamics of Nonlinear Markov Processes
Gorban, A N
2015-01-01
The nonlinear Markov processes are the measure-valued dynamical systems which preserve positivity. They can be represented as the law of large numbers limits of general Markov models of interacting particles. In physics, the kinetic equations allow Lyapunov functionals (entropy, free energy, etc.). This may be considered as a sort of inheritance of the Lyapunov functionals from the microscopic master equations. We study nonlinear Markov processes that inherit thermodynamic properties from the microscopic linear Markov processes. We develop the thermodynamics of nonlinear Markov processes and analyze the asymptotic assumption, which are sufficient for this inheritance.
Nonlinear spectral unmixing of hyperspectral images using Gaussian processes
Altmann, Yoann; McLaughlin, Steve; Tourneret, Jean-Yves
2012-01-01
This paper presents an unsupervised algorithm for nonlinear unmixing of hyperspectral images. The proposed model assumes that the pixel reflectances result from a nonlinear function of the abundance vectors associated with the pure spectral components. We assume that the spectral signatures of the pure components and the nonlinear function are unknown. The first step of the proposed method consists of the Bayesian estimation of the abundance vectors for all the image pixels and the nonlinear function relating the abundance vectors to the observations. The endmembers are subsequently estimated using Gaussian process regression. The performance of the unmixing strategy is evaluated with simulations conducted on synthetic and real data.
Linear and Nonlinear Heart Rate Variability Indexes in Clinical Practice
Directory of Open Access Journals (Sweden)
Buccelletti Francesco
2012-01-01
Full Text Available Biological organisms have intrinsic control systems that act in response to internal and external stimuli maintaining homeostasis. Human heart rate is not regular and varies in time and such variability, also known as heart rate variability (HRV, is not random. HRV depends upon organism's physiologic and/or pathologic state. Physicians are always interested in predicting patient's risk of developing major and life-threatening complications. Understanding biological signals behavior helps to characterize patient's state and might represent a step toward a better care. The main advantage of signals such as HRV indexes is that it can be calculated in real time in noninvasive manner, while all current biomarkers used in clinical practice are discrete and imply blood sample analysis. In this paper HRV linear and nonlinear indexes are reviewed and data from real patients are provided to show how these indexes might be used in clinical practice.
Bubble nonlinear dynamics and stimulated scattering process
Jie, Shi; De-Sen, Yang; Sheng-Guo, Shi; Bo, Hu; Hao-Yang, Zhang; Shi-Yong, Hu
2016-02-01
A complete understanding of the bubble dynamics is deemed necessary in order to achieve their full potential applications in industry and medicine. For this purpose it is first needed to expand our knowledge of a single bubble behavior under different possible conditions including the frequency and pressure variations of the sound field. In addition, stimulated scattering of sound on a bubble is a special effect in sound field, and its characteristics are associated with bubble oscillation mode. A bubble in liquid can be considered as a representative example of nonlinear dynamical system theory with its resonance, and its dynamics characteristics can be described by the Keller-Miksis equation. The nonlinear dynamics of an acoustically excited gas bubble in water is investigated by using theoretical and numerical analysis methods. Our results show its strongly nonlinear behavior with respect to the pressure amplitude and excitation frequency as the control parameters, and give an intuitive insight into stimulated sound scattering on a bubble. It is seen that the stimulated sound scattering is different from common dynamical behaviors, such as bifurcation and chaos, which is the result of the nonlinear resonance of a bubble under the excitation of a high amplitude acoustic sound wave essentially. The numerical analysis results show that the threshold of stimulated sound scattering is smaller than those of bifurcation and chaos in the common condition. Project supported by the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT1228) and the Young Scientists Fund of the National Natural Science Foundation of China (Grant Nos. 11204050 and 11204049).
NONLINEAR MODEL PREDICTIVE CONTROL OF CHEMICAL PROCESSES
Directory of Open Access Journals (Sweden)
R. G. SILVA
1999-03-01
Full Text Available A new algorithm for model predictive control is presented. The algorithm utilizes a simultaneous solution and optimization strategy to solve the model's differential equations. The equations are discretized by equidistant collocation, and along with the algebraic model equations are included as constraints in a nonlinear programming (NLP problem. This algorithm is compared with the algorithm that uses orthogonal collocation on finite elements. The equidistant collocation algorithm results in simpler equations, providing a decrease in computation time for the control moves. Simulation results are presented and show a satisfactory performance of this algorithm.
Coupled parametric processes in binary nonlinear photonic structures
Saygin, M Yu
2016-01-01
We study parametric interactions in a new type of nonlinear photonic structures, which is realized in the vicinity of a pair of nonlinear crystals. In this kind of structure, which we call binary, multiple nonlinear optical processes can be implemented simultaneously, owing to multiple phase-matching conditions, fulfilled separately in the constituent crystals. The coupling between the nonlinear processes by means of modes sharing similar frequency is attained by the spatially-broadband nature of the parametric fields. We investigate the spatial properties of the fields generated in the binary structure constructed from periodically poled crystals for the two examples: 1) single parametric down-conversion, and 2) coupled parametric down-conversion and up-conversion processes. The efficacy of the fields' generation in these examples is analyzed through comparison with the cases of traditional single periodically poled crystal and aperiodic photonic structure, respectively. It has been shown that the relative s...
Yashkir, O. V.; Yashkir, Yu N.
1987-11-01
An investigation is made of nonlinear optical interaction of light propagating in a planar waveguide with surface polaritons. Reduced wave equations for the amplitudes of the waveguide modes and surface polaritons are used to study the characteristics of generation of surface polaritons of difference frequency, parametric frequency up-conversion of the polaritons, and stimulated Raman scattering by the polaritons. An analysis is made of the characteristic properties of the investigated nonlinear optical processes.
First Principles Modeling of Nonlinear Incidence Rates in Seasonal Epidemics
2011-01-01
In this paper we used a general stochastic processes framework to derive from first principles the incidence rate function that characterizes epidemic models. We investigate a particular case, the Liu-Hethcote-van den Driessche's (LHD) incidence rate function, which results from modeling the number of successful transmission encounters as a pure birth process. This derivation also takes into account heterogeneity in the population with regard to the per individual transmission probability. We...
Si-rich Silicon Nitride for Nonlinear Signal Processing Applications.
Lacava, Cosimo; Stankovic, Stevan; Khokhar, Ali Z; Bucio, T Dominguez; Gardes, F Y; Reed, Graham T; Richardson, David J; Petropoulos, Periklis
2017-02-02
Nonlinear silicon photonic devices have attracted considerable attention thanks to their ability to show large third-order nonlinear effects at moderate power levels allowing for all-optical signal processing functionalities in miniaturized components. Although significant efforts have been made and many nonlinear optical functions have already been demonstrated in this platform, the performance of nonlinear silicon photonic devices remains fundamentally limited at the telecom wavelength region due to the two photon absorption (TPA) and related effects. In this work, we propose an alternative CMOS-compatible platform, based on silicon-rich silicon nitride that can overcome this limitation. By carefully selecting the material deposition parameters, we show that both of the device linear and nonlinear properties can be tuned in order to exhibit the desired behaviour at the selected wavelength region. A rigorous and systematic fabrication and characterization campaign of different material compositions is presented, enabling us to demonstrate TPA-free CMOS-compatible waveguides with low linear loss (~1.5 dB/cm) and enhanced Kerr nonlinear response (Re{γ} = 16 Wm(-1)). Thanks to these properties, our nonlinear waveguides are able to produce a π nonlinear phase shift, paving the way for the development of practical devices for future optical communication applications.
Oxygen consumption of cycle ergometry is nonlinearly related to work rate and pedal rate.
Londeree, B R; Moffitt-Gerstenberger, J; Padfield, J A; Lottmann, D
1997-06-01
The purpose of the study was to develop an equation to predict the oxygen cost of cycle ergometry. Forty subjects performed an incremental cycle ergometer test on three occasions at 50, 70, or 90 rpm in a counterbalanced order. Work rate was incremented every 5 or 6 min when steady rate values were achieved. To ensure accurate work rates, ergometer resistance was calibrated and flywheel revolutions were electronically measured. Oxygen consumption was measured with a computer interfaced system which provided results every minute. Oxygen consumption (mL.min-1) was the dependent variable, and independent variables were work rate (WR in kgm.min-1), pedal rate (rpm), weight (Kg), and gender (males, 0; females, 1). The following nonlinear equation was selected; VO2 = 0.42.WR1.2 + 0.00061.rpm3 + 6.35.Wt + 0.1136.RPM50.WR-0.10144.RPM90-WR-52-Gender, R2 = 0.9961, Sy.x = 106 mL.min-1, where RPM50: 50 rpm = 1, and RPM90: 90 rpm = 1, else = 0. It was concluded that the oxygen cost of cycle ergometry is nonlinearly related to work rate and pedal rate, linearly related to weight, and that females use less oxygen for a particular work rate.
Comparing Linear and Non-linear Benchmarks of Exchange Rate Forecasting
SJ Retief, M Pretorius and I Botha
2015-01-01
Throughout the past 3 decades, the random walk model served as exchange rate forecasting benchmark to verify that a model is able to outperform a random process. However, its application as forecasting benchmark is contradictory. Rather than serving as a benchmark that explains exchange rate behaviour, it serves as a benchmark of what we do not understand in exchange rate forecasting â€“ the random component. In order to accommodate for the observed mean reverting and non-linear patterns in e...
Saturation process of nonlinear standing waves
Institute of Scientific and Technical Information of China (English)
马大猷; 刘克
1996-01-01
The sound pressure of the nonlinear standing waves is distorted as expected, but also tends to saturate as being found in standing-wave tube experiments with increasing sinusoidal excitation. Saturation conditions were not actually reached, owing to limited excitation power, but the evidence of tendency to saturation is without question. It is the purpose of this investigation to find the law of saturation from the existing experimental data. The results of curve fitting indicate that negative feedback limits the growth of sound pressure with increasing excitation, the growth of the fundamental and the second harmonic by the negative feedback of their sound pressures, and the growth of the third and higher harmonics, however, by their energies (sound pressures squared). The growth functions of all the harmonics are derived, which are confirmed by the experiments. The saturation pressures and their properties are found.
Adaptive control method for nonlinear time-delay processes
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Two complex properties,varying time-delay and block-oriented nonlinearity,are very common in chemical engineering processes and not easy to be controlled by routine control methods.Aimed at these two complex properties,a novel adaptive control algorithm the basis of nonlinear OFS(orthonormal functional series) model is proposed.First,the hybrid model which combines OFS and Volterra series is introduced.Then,a stable state feedback strategy is used to construct a nonlinear adaptive control algorithm that can guarantee the closed-loop stability and can track the set point curve without steady-state errors.Finally,control simulations and experiments on a nonlinear process with varying time-delay are presented.A number of experimental results validate the efficiency and superiority of this algorithm.
Nonlinear fiber applications for ultrafast all-optical signal processing
Kravtsov, Konstantin
In the present dissertation different aspects of all-optical signal processing, enabled by the use of nonlinear fibers, are studied. In particular, we focus on applications of a novel heavily GeO2-doped (HD) nonlinear fiber, that appears to be superior to many other types of nonlinear fibers because of its high nonlinearity and suitability for the use in nonlinear optical loop mirrors (NOLMs). Different functions, such as all-optical switching, thresholding, and wavelength conversion, are demonstrated with the HD fibers in the NOLM configuration. These basic functions are later used for realization of ultrafast time-domain demultiplexers, clock recovery, detectors of short pulses in stealth communications, and primitive elements for analog computations. Another important technology that benefits from the use of nonlinear fiber-based signal processing is optical code-division multiple access (CDMA). It is shown in both theory and experiment that all-optical thresholding is a unique way of improving existing detection methods for optical CDMA. Also, it is the way of implementation of true asynchronous optical spread-spectrum networks, which allows full realization of optical CDMA potential. Some aspects of quantum signal processing and manipulation of quantum states are also studied in this work. It is shown that propagation and collisions of Thirring solitons lead to a substantial squeezing of quantum states, which may find applications for generation of squeezed light.
Lavdas, Spyros; You, Jie; Osgood, Richard M.; Panoiu, Nicolae C.
2015-08-01
We present recent results pertaining to pulse reshaping and optical signal processing using optical nonlinearities of silicon-based tapered photonic wires and photonic crystal waveguides. In particular, we show how nonlinearity and dispersion engineering of tapered photonic wires can be employed to generate optical similaritons and achieve more than 10× pulse compression. We also discuss the properties of four-wave mixing pulse amplification and frequency conversion efficiency in long-period Bragg waveguides and photonic crystal waveguides. Finally, the influence of linear and nonlinear optical effects on the transmission bit-error rate in uniform photonic wires and photonic crystal waveguides made of silicon is discussed.
Nonlinear Statistical Process Monitoring and Fault Detection Using Kernel ICA
Institute of Scientific and Technical Information of China (English)
ZHANG Xi; YAN Wei-wu; ZHAO Xu; SHAO Hui-he
2007-01-01
A novel nonlinear process monitoring and fault detection method based on kernel independent component analysis (ICA) is proposed. The kernel ICA method is a two-phase algorithm: whitened kernel principal component (KPCA) plus ICA. KPCA spheres data and makes the data structure become as linearly separable as possible by virtue of an implicit nonlinear mapping determined by kernel. ICA seeks the projection directions in the KPCA whitened space, making the distribution of the projected data as non-gaussian as possible. The application to the fluid catalytic cracking unit (FCCU) simulated process indicates that the proposed process monitoring method based on kernel ICA can effectively capture the nonlinear relationship in process variables. Its performance significantly outperforms monitoring method based on ICA or KPCA.
Modeling and stability analysis of the nonlinear reactive sputtering process
Directory of Open Access Journals (Sweden)
György Katalin
2011-12-01
Full Text Available The model of the reactive sputtering process has been determined from the dynamic equilibrium of the reactive gas inside the chamber and the dynamic equilibrium of the sputtered metal atoms which form the compound with the reactive gas atoms on the surface of the substrate. The analytically obtained dynamical model is a system of nonlinear differential equations which can result in a histeresis-type input/output nonlinearity. The reactive sputtering process has been simulated by integrating these differential equations. Linearization has been applied for classical analysis of the sputtering process and control system design.
An Agent Interaction Based Method for Nonlinear Process Plan Scheduling
Institute of Scientific and Technical Information of China (English)
GAO Qinglu; WU Bo; GUO Guang
2006-01-01
This article puts forward a scheduling method for nonlinear process plan shop floor. Task allocation and load balance are realized by bidding mechanism. Though the agent interaction process, the execution of tasks is determined and the coherence of manufacturing decision is verified. The employment of heuristic index can help to optimize the system performance.
Innovation as a Nonlinear Process and the Scientometric Perspective
Leydesdorff, L.; Rotolo, D.; de Nooy, W.; Archambault, E.; Gingras, Y.; Larivière, V.
2012-01-01
The process of innovation follows non-linear patterns across the domains of science, technology, and the economy. Novel bibliometric mapping techniques can be used to investigate and represent distinctive, but complementary perspectives on the innovation process (e.g., "demand" and "supply") as well
Zenteno, Efrain; Piazza, Roberto; M. R. Bhavani Shankar; Rönnow, Daniel; Ottersten, Björn
2015-01-01
A digital predistortion (DPD) scheme is presented for non-linear distortion mitigation in multi-carrier satellite communication channels. The proposed DPD has a multiple-input multiple-output architecture similar to data DPD schemes. However, it enhances the mitigation performance of data DPDs using a multi-rate processing algorithm to achieve spectrum broadening of non-linear operators. Compared to single carrier (single-input single-output) signal (waveform) DPD schemes, the proposed DPD ha...
First principles modeling of nonlinear incidence rates in seasonal epidemics.
Directory of Open Access Journals (Sweden)
José M Ponciano
2011-02-01
Full Text Available In this paper we used a general stochastic processes framework to derive from first principles the incidence rate function that characterizes epidemic models. We investigate a particular case, the Liu-Hethcote-van den Driessche's (LHD incidence rate function, which results from modeling the number of successful transmission encounters as a pure birth process. This derivation also takes into account heterogeneity in the population with regard to the per individual transmission probability. We adjusted a deterministic SIRS model with both the classical and the LHD incidence rate functions to time series of the number of children infected with syncytial respiratory virus in Banjul, Gambia and Turku, Finland. We also adjusted a deterministic SEIR model with both incidence rate functions to the famous measles data sets from the UK cities of London and Birmingham. Two lines of evidence supported our conclusion that the model with the LHD incidence rate may very well be a better description of the seasonal epidemic processes studied here. First, our model was repeatedly selected as best according to two different information criteria and two different likelihood formulations. The second line of evidence is qualitative in nature: contrary to what the SIRS model with classical incidence rate predicts, the solution of the deterministic SIRS model with LHD incidence rate will reach either the disease free equilibrium or the endemic equilibrium depending on the initial conditions. These findings along with computer intensive simulations of the models' Poincaré map with environmental stochasticity contributed to attain a clear separation of the roles of the environmental forcing and the mechanics of the disease transmission in shaping seasonal epidemics dynamics.
First principles modeling of nonlinear incidence rates in seasonal epidemics.
Ponciano, José M; Capistrán, Marcos A
2011-02-01
In this paper we used a general stochastic processes framework to derive from first principles the incidence rate function that characterizes epidemic models. We investigate a particular case, the Liu-Hethcote-van den Driessche's (LHD) incidence rate function, which results from modeling the number of successful transmission encounters as a pure birth process. This derivation also takes into account heterogeneity in the population with regard to the per individual transmission probability. We adjusted a deterministic SIRS model with both the classical and the LHD incidence rate functions to time series of the number of children infected with syncytial respiratory virus in Banjul, Gambia and Turku, Finland. We also adjusted a deterministic SEIR model with both incidence rate functions to the famous measles data sets from the UK cities of London and Birmingham. Two lines of evidence supported our conclusion that the model with the LHD incidence rate may very well be a better description of the seasonal epidemic processes studied here. First, our model was repeatedly selected as best according to two different information criteria and two different likelihood formulations. The second line of evidence is qualitative in nature: contrary to what the SIRS model with classical incidence rate predicts, the solution of the deterministic SIRS model with LHD incidence rate will reach either the disease free equilibrium or the endemic equilibrium depending on the initial conditions. These findings along with computer intensive simulations of the models' Poincaré map with environmental stochasticity contributed to attain a clear separation of the roles of the environmental forcing and the mechanics of the disease transmission in shaping seasonal epidemics dynamics.
Nonlinear partial least squares with Hellinger distance for nonlinear process monitoring
Harrou, Fouzi
2017-02-16
This paper proposes an efficient data-based anomaly detection method that can be used for monitoring nonlinear processes. The proposed method merges advantages of nonlinear projection to latent structures (NLPLS) modeling and those of Hellinger distance (HD) metric to identify abnormal changes in highly correlated multivariate data. Specifically, the HD is used to quantify the dissimilarity between current NLPLS-based residual and reference probability distributions. The performances of the developed anomaly detection using NLPLS-based HD technique is illustrated using simulated plug flow reactor data.
Nonlinear Dynamic Characteristics of Combustion Wave in SHS Process
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The characteristic of combustion wave and its change were analyzed by numerical value calculation and computer simulation,based on the combustion dynamical model of SHS process. It is shown that with the change of condition parameters in SHS process various time-space order combustion waves appear.It is concluded from non-liner dynamical mechanism analysis that the strong coupling of two non-linear dynamical processes is the dynamical mechanism causing the time-space order dissipation structures.
Relaxation Processes in Nonlinear Optical Polymer Films
Directory of Open Access Journals (Sweden)
S.N. Fedosov
2010-01-01
Full Text Available Dielectric properties of the guest-host polystyrene/DR1 system have been studied by the AC dielectric spectroscopy method at frequencies from 1 Hz to 0,5 MHz and by the thermally stimulated depolarization current (TSDC method from – 160 to 0 °C. The relaxation peaks at infra-low frequencies from 10 – 5to 10–2 Hz were also calculated using the Hamon’s approximation. Three relaxation processes, namely, α, β and δ ones were identified from the TSDC peaks, while the ε''(fdependence showed a non-Debye ρ-peak narrowing with temperature. The activation energy of the α-relaxation appeared to be 2,57 eV, while that of the γ-process was 0,52 eV. Temperature dependence of the relaxation time is agreed with the Williams-Landel-Ferry model. The ε''(fpeaks were fitted to Havriliak-Negami’s expression and the corresponding distribution parameters were obtained.
Ultra-Fast Optical Signal Processing in Nonlinear Silicon Waveguides
DEFF Research Database (Denmark)
Oxenløwe, Leif Katsuo; Galili, Michael; Pu, Minhao;
2011-01-01
We describe recent demonstrations of exploiting highly nonlinear silicon nanowires for processing Tbit/s optical data signals. We perform demultiplexing and optical waveform sampling of 1.28 Tbit/s and wavelength conversion of 640 Gbit/s data signals....
Wei, Song; Chen, Wen; Hon, Y. C.
2016-11-01
This paper investigates the temporal effects in the modeling of flows through porous media and particles transport. Studies will be made among the time fractional diffusion model and two classical nonlinear diffusion models. The effects of the parameters upon the mentioned models have been studied. By simulating the sub-diffusion processes and comparing the numerical results of these models under different boundary conditions, we can conclude that the time fractional diffusion model is more suitable for simulating the sub-diffusion with steady diffusion rate; whereas the nonlinear models are more appropriate for depicting the sub-diffusion under changing diffusion rate.
Age and Creative Productivity: Nonlinear Estimation of an Information-Processing Model.
Simonton, Dean Keith
1989-01-01
Applied two-step cognitive model to relationship between age and creative productivity. Selected ideation and elaboration rates as information-processing parameters that define mathematical function which describes age curves and specifies their variance across disciplines. Applied non-linear estimation program to further validate model. Despite…
Directory of Open Access Journals (Sweden)
Syed Zaki Hassan Kazmi
Full Text Available The dynamical fluctuations in the rhythms of biological systems provide valuable information about the underlying functioning of these systems. During the past few decades analysis of cardiac function based on the heart rate variability (HRV; variation in R wave to R wave intervals has attracted great attention, resulting in more than 17000-publications (PubMed list. However, it is still controversial about the underling mechanisms of HRV. In this study, we performed both linear (time domain and frequency domain and nonlinear analysis of HRV data acquired from humans and animals to identify the relationship between HRV and heart rate (HR. The HRV data consists of the following groups: (a human normal sinus rhythm (n = 72; (b human congestive heart failure (n = 44; (c rabbit sinoatrial node cells (SANC; n = 67; (d conscious rat (n = 11. In both human and animal data at variant pathological conditions, both linear and nonlinear analysis techniques showed an inverse correlation between HRV and HR, supporting the concept that HRV is dependent on HR, and therefore, HRV cannot be used in an ordinary manner to analyse autonomic nerve activity of a heart.
Modeling Autoregressive Processes with Moving-Quantiles-Implied Nonlinearity
Directory of Open Access Journals (Sweden)
Isao Ishida
2015-01-01
Full Text Available We introduce and investigate some properties of a class of nonlinear time series models based on the moving sample quantiles in the autoregressive data generating process. We derive a test fit to detect this type of nonlinearity. Using the daily realized volatility data of Standard & Poor’s 500 (S&P 500 and several other indices, we obtained good performance using these models in an out-of-sample forecasting exercise compared with the forecasts obtained based on the usual linear heterogeneous autoregressive and other models of realized volatility.
Influence of forced respiration on nonlinear dynamics in heart rate variability
DEFF Research Database (Denmark)
Kanters, J K; Højgaard, M V; Agner, E;
1997-01-01
of this study was to test whether the known nonlinear input from spontaneous respiration is a source for the nonlinearities in heart rate variability. Twelve healthy subjects were examined in supine position with 3-h electrocardiogram recordings during both spontaneous and forced respiration in accordance...... expressed as the nonlinear prediction error did not differ between spontaneous respiration, 32.3 +/- 3.4 ms, and forced respiration, 31.9 +/- 5.7. It is concluded that the origin of the nonlinear dynamics in heart rate variability is not a nonlinear input from the respiration into the cardiovascular...... oscillator. Additional studies are needed to elucidate the mechanisms behind the nonlinear dynamics in heart rate variability....
New CMOS Compatible Platforms for Integrated Nonlinear Optical Signal Processing
Moss, D J
2014-01-01
Nonlinear photonic chips have succeeded in generating and processing signals all-optically with performance far superior to that possible electronically - particularly with respect to speed. Although silicon-on-insulator has been the leading platform for nonlinear optics, its high two-photon absorption at telecommunications wavelengths poses a fundamental limitation. This paper reviews some of the recent achievements in CMOS-compatible platforms for nonlinear optics, focusing on amorphous silicon and Hydex glass, highlighting their potential future impact as well as the challenges to achieving practical solutions for many key applications. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement.
Short- and long-term variations in non-linear dynamics of heart rate variability
DEFF Research Database (Denmark)
Kanters, J K; Højgaard, M V; Agner, E;
1996-01-01
OBJECTIVES: The purpose of the study was to investigate the short- and long-term variations in the non-linear dynamics of heart rate variability, and to determine the relationships between conventional time and frequency domain methods and the newer non-linear methods of characterizing heart rate...... variability. METHODS: Twelve healthy subjects were investigated by 3-h ambulatory ECG recordings repeated on 3 separate days. Correlation dimension, non-linear predictability, mean heart rate, and heart rate variability in the time and frequency domains were measured and compared with the results from...... corresponding surrogate time series. RESULTS: A small significant amount of non-linear dynamics exists in heart rate variability. Correlation dimensions and non-linear predictability are relatively specific parameters for each individual examined. The correlation dimension is inversely correlated to the heart...
Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report
Energy Technology Data Exchange (ETDEWEB)
Tataronis, J. A.
2004-06-01
This program treats theoretically low frequency linear and nonlinear wave processes in magnetized plasmas. A primary objective has been to evaluate the effectiveness of MHD waves to heat plasma and drive current in toroidal configurations. The research covers the following topics: (1) the existence and properties of the MHD continua in plasma equilibria without spatial symmetry; (2) low frequency nonresonant current drive and nonlinear Alfven wave effects; and (3) nonlinear electron acceleration by rf and random plasma waves. Results have contributed to the fundamental knowledge base of MHD activity in symmetric and asymmetric toroidal plasmas. Among the accomplishments of this research effort, the following are highlighted: Identification of the MHD continuum mode singularities in toroidal geometry. Derivation of a third order ordinary differential equation that governs nonlinear current drive in the singular layers of the Alfvkn continuum modes in axisymmetric toroidal geometry. Bounded solutions of this ODE implies a net average current parallel to the toroidal equilibrium magnetic field. Discovery of a new unstable continuum of the linearized MHD equation in axially periodic circular plasma cylinders with shear and incompressibility. This continuum, which we named “accumulation continuum” and which is related to ballooning modes, arises as discrete unstable eigenfrequency accumulate on the imaginary frequency axis in the limit of large mode numbers. Development of techniques to control nonlinear electron acceleration through the action of multiple coherent and random plasmas waves. Two important elements of this program aye student participation and student training in plasma theory.
Process and meaning: nonlinear dynamics and psychology in visual art.
Zausner, Tobi
2007-01-01
Creating and viewing visual art are both nonlinear experiences. Creating a work of art is an irreversible process involving increasing levels of complexity and unpredictable events. Viewing art is also creative with collective responses forming autopoietic structures that shape cultural history. Artists work largely from the chaos of the unconscious and visual art contains elements of chaos. Works of art by the author are discussed in reference to nonlinear dynamics. "Travelogues" demonstrates continued emerging interpretations and a deterministic chaos. "Advice to the Imperfect" signifies the resolution of paradox in the nonlinear tension of opposites. "Quanah" shows the nonlinear tension of opposites as an ongoing personal evolution. "The Mother of All Things" depicts seemingly separate phenomena arising from undifferentiated chaos. "Memories" refers to emotional fixations as limit cycles. "Compassionate Heart," "Wind on the Lake," and "Le Mal du Pays" are a series of works in fractal format focusing on the archetype of the mother and child. "Sameness, Depth of Mystery" addresses the illusion of hierarchy and the dynamics of symbols. In "Chasadim" the origin of worlds and the regeneration of individuals emerge through chaos. References to chaos in visual art mirror the nonlinear complexity of life.
Nonlinear Processes in Magnetic Nanodots under Perpendicular Pumping: Micromagnetic Simulations
Directory of Open Access Journals (Sweden)
D.V. Slobodiainuk
2013-03-01
Full Text Available Processes that take place in permalloy nanodots under external electromagnetic pumping are considered. It is shown that in such system similar to bulk samples Suhl and kinetic instability processes are possible. Using micromagnetic simulations approach key features of mode excitation with an external pumping power increase were revealed. Results of the simulations were compared with published experimental data dedicated to investigation of magnetic nanodotes in nonlinear regime.
Institute of Scientific and Technical Information of China (English)
GUO Qintao; ZHANG Lingmi; TAO Zheng
2008-01-01
Thin wall component is utilized to absorb impact energy of a structure. However, the dynamic behavior of such thin-walled structure is highly non-linear with material, geometry and boundary non-linearity. A model updating and validation procedure is proposed to build accurate finite element model of a frame structure with a non-linear thin-walled component for dynamic analysis. Design of experiments (DOE) and principal component decomposition (PCD) approach are applied to extract dynamic feature from nonlinear impact response for correlation of impact test result and FE model of the non-linear structure. A strain-rate-dependent non-linear model updating method is then developed to build accurate FE model of the structure. Computer simulation and a real frame structure with a highly non-linear thin-walled component are employed to demonstrate the feasibility and effectiveness of the proposed approach.
Optoelectronic and nonlinear optical processes in low dimensional semiconductors
Indian Academy of Sciences (India)
B P Singh
2006-11-01
Spatial confinement of quantum excitations on their characteristic wavelength scale in low dimensional materials offers unique possibilities to engineer the electronic structure and thereby control their physical properties by way of simple manipulation of geometrical parameters. This has led to an overwhelming interest in quasi-zero dimensional semiconductors or quantum dots as tunable materials for multitude of exciting applications in optoelectronic and nonlinear optical devices and quantum information processing. Large nonlinear optical response and high luminescence quantum yield expected in these systems is a consequence of huge enhancement of transition probabilities ensuing from quantum confinement. High quantum efficiency of photoluminescence, however, is not usually realized in the case of bare semiconductor nanoparticles owing to the presence of surface states. In this talk, I will focus on the role of quantum confinement and surface states in ascertaining nonlinear optical and optoelectronic properties of II–VI semiconductor quantum dots and their nanocomposites. I will also discuss the influence of nonlinear optical processes on their optoelectronic characteristics.
Nonlinear analysis and control of a continuous fermentation process
DEFF Research Database (Denmark)
Szederkényi, G.; Kristensen, Niels Rode; Hangos, K.M
2002-01-01
open-loop system properties, to explore the possible control difficulties and to select the system output to be used in the control structure. A wide range of controllers are tested including pole placement and LQ controllers, feedback and input–output linearization controllers and a nonlinear...... controller based on direct passivation. The comparison is based on time-domain performance and on investigating the stability region, robustness and tuning possibilities of the controllers. Controllers using partial state feedback of the substrate concentration and not directly depending on the reaction rate...... are recommended for the simple fermenter. Passivity based controllers have been found to be globally stable, not very sensitive to the uncertainties in the reaction rate and controller parameter but they require full nonlinear state feedback....
SIVS EPIDEMIC MODELS WITH INFECTION AGE AND NONLINEAR VACCINATION RATE
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Vaccination is a very important strategy for the elimination of infectious diseaVaccination is a very important strategy for the elimination of infectious diseases. A SIVS epidemic model with infection age and nonlinear vaccination has been formulated in this paper. Using the theory of differential and integral equation, we show the local asymptotic stability of the infection-free equilibrium and the endemic equilibrium under some assumptions.
NON-LINEAR FINITE ELEMENT MODELING OF DEEP DRAWING PROCESS
Directory of Open Access Journals (Sweden)
Hasan YILDIZ
2004-03-01
Full Text Available Deep drawing process is one of the main procedures used in different branches of industry. Finding numerical solutions for determination of the mechanical behaviour of this process will save time and money. In die surfaces, which have complex geometries, it is hard to determine the effects of parameters of sheet metal forming. Some of these parameters are wrinkling, tearing, and determination of the flow of the thin sheet metal in the die and thickness change. However, the most difficult one is determination of material properties during plastic deformation. In this study, the effects of all these parameters are analyzed before producing the dies. The explicit non-linear finite element method is chosen to be used in the analysis. The numerical results obtained for non-linear material and contact models are also compared with the experiments. A good agreement between the numerical and the experimental results is obtained. The results obtained for the models are given in detail.
Nonlinear Silicon Photonic Signal Processing Devices for Future Optical Networks
Directory of Open Access Journals (Sweden)
Cosimo Lacava
2017-01-01
Full Text Available In this paper, we present a review on silicon-based nonlinear devices for all optical nonlinear processing of complex telecommunication signals. We discuss some recent developments achieved by our research group, through extensive collaborations with academic partners across Europe, on optical signal processing using silicon-germanium and amorphous silicon based waveguides as well as novel materials such as silicon rich silicon nitride and tantalum pentoxide. We review the performance of four wave mixing wavelength conversion applied on complex signals such as Differential Phase Shift Keying (DPSK, Quadrature Phase Shift Keying (QPSK, 16-Quadrature Amplitude Modulation (QAM and 64-QAM that dramatically enhance the telecom signal spectral efficiency, paving the way to next generation terabit all-optical networks.
Preface "Nonlinear processes in oceanic and atmospheric flows"
Directory of Open Access Journals (Sweden)
E. García-Ladona
2010-05-01
Full Text Available Nonlinear phenomena are essential ingredients in many oceanic and atmospheric processes, and successful understanding of them benefits from multidisciplinary collaboration between oceanographers, meteorologists, physicists and mathematicians. The present Special Issue on "Nonlinear Processes in Oceanic and Atmospheric Flows" contains selected contributions from attendants to the workshop which, in the above spirit, was held in Castro Urdiales, Spain, in July 2008. Here we summarize the Special Issue contributions, which include papers on the characterization of ocean transport in the Lagrangian and in the Eulerian frameworks, generation and variability of jets and waves, interactions of fluid flow with plankton dynamics or heavy drops, scaling in meteorological fields, and statistical properties of El Niño Southern Oscillation.
Preface "Nonlinear processes in oceanic and atmospheric flows"
Mancho, A M; Turiel, A; Hernandez-Garcia, E; Lopez, C; Garcia-Ladona, E; 10.5194/npg-17-283-2010
2010-01-01
Nonlinear phenomena are essential ingredients in many oceanic and atmospheric processes, and successful understanding of them benefits from multidisciplinary collaboration between oceanographers, meteorologists, physicists and mathematicians. The present Special Issue on ``Nonlinear Processes in Oceanic and Atmospheric Flows'' contains selected contributions from attendants to the workshop which, in the above spirit, was held in Castro Urdiales, Spain, in July 2008. Here we summarize the Special Issue contributions, which include papers on the characterization of ocean transport in the Lagrangian and in the Eulerian frameworks, generation and variability of jets and waves, interactions of fluid flow with plankton dynamics or heavy drops, scaling in meteorological fields, and statistical properties of El Ni\\~no Southern Oscillation.
High-speed signal processing using highly nonlinear optical fibres
DEFF Research Database (Denmark)
Peucheret, Christophe; Oxenløwe, Leif Katsuo; Mulvad, Hans Christian Hansen
2009-01-01
relying on the phase of the optical field. Topics covered include all-optical switching of 640 Gbit/s and 1.28 Tbit/s serial data, wavelength conversion at 640 Gbit/s, optical amplitude regeneration of differential phase shift keying (DPSK) signals, as well as midspan spectral inversion for differential 8......We review recent progress in all-optical signal processing techniques making use of conventional silica-based highly nonlinear fibres. In particular, we focus on recent demonstrations of ultra-fast processing at 640 Gbit/s and above, as well as on signal processing of novel modulation formats...
Double resonant processes in $\\chi^{(2)}$ nonlinear periodic media
Konotop, V. V.; Kuzmiak, V.
2000-01-01
In a one-dimensional periodic nonlinear $\\chi^{(2)}$ medium, by choosing a proper material and geometrical parameters of the structure, it is possible to obtain two matching conditions for simultaneous generation of second and third harmonics. This leads to new diversity of the processes of the resonant three-wave interactions, which are discussed within the framework of slowly varying envelope approach. In particular, we concentrate on the fractional conversion of the frequency $\\omega \\to (...
SAR processing with non-linear FM chirp waveforms.
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter
2006-12-01
Nonlinear FM (NLFM) waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM (LFM) waveform with equivalent sidelobe filtering. This report presents details of processing NLFM waveforms in both range and Doppler dimensions, with special emphasis on compensating intra-pulse Doppler, often cited as a weakness of NLFM waveforms.
Energy Technology Data Exchange (ETDEWEB)
Reber, T. J.; Plumb, N. C.; Waugh, J. A.; Dessau, D. S. [Department of Physics, University of Colorado, Boulder, Colorado 80309-0390 (United States)
2014-04-15
Detector counting rate nonlinearity, though a known problem, is commonly ignored in the analysis of angle resolved photoemission spectroscopy where modern multichannel electron detection schemes using analog intensity scales are used. We focus on a nearly ubiquitous “inverse saturation” nonlinearity that makes the spectra falsely sharp and beautiful. These artificially enhanced spectra limit accurate quantitative analysis of the data, leading to mistaken spectral weights, Fermi energies, and peak widths. We present a method to rapidly detect and correct for this nonlinearity. This algorithm could be applicable for a wide range of nonlinear systems, beyond photoemission spectroscopy.
Photonic Crystal Nanocavity Devices for Nonlinear Signal Processing
DEFF Research Database (Denmark)
Yu, Yi
, membranization of InP/InGaAs structure and wet etching. Experimental investigation of the switching dynamics of InP photonic crystal nanocavity structures are carried out using short-pulse homodyne pump-probe techniques, both in the linear and nonlinear region where the cavity is perturbed by a relatively small......This thesis deals with the investigation of InP material based photonic crystal cavity membrane structures, both experimentally and theoretically. The work emphasizes on the understanding of the physics underlying the structures’ nonlinear properties and their applications for all-optical signal...... and large pump power. The experimental results are compared with coupled mode equations developed based on the first order perturbation theory, and carrier rate equations we established for the dynamics of the carrier density governing the cavity properties. The experimental observations show a good...
A comparison of nonlinear media for parametric all-optical signal processing
DEFF Research Database (Denmark)
Martinez Diaz, Jordi; Bohigas Nadal, Jaume; Vukovic, Dragana;
2013-01-01
We systematically compare nonlinear media for parametric signal processing by determining the minimum pump power that is required for a given conversion efficiency in a degenerate four-wave mixing process, including the effect of nonlinear loss....
Nonlinear Statistical Signal Processing: A Particle Filtering Approach
Energy Technology Data Exchange (ETDEWEB)
Candy, J
2007-09-19
A introduction to particle filtering is discussed starting with an overview of Bayesian inference from batch to sequential processors. Once the evolving Bayesian paradigm is established, simulation-based methods using sampling theory and Monte Carlo realizations are discussed. Here the usual limitations of nonlinear approximations and non-gaussian processes prevalent in classical nonlinear processing algorithms (e.g. Kalman filters) are no longer a restriction to perform Bayesian inference. It is shown how the underlying hidden or state variables are easily assimilated into this Bayesian construct. Importance sampling methods are then discussed and shown how they can be extended to sequential solutions implemented using Markovian state-space models as a natural evolution. With this in mind, the idea of a particle filter, which is a discrete representation of a probability distribution, is developed and shown how it can be implemented using sequential importance sampling/resampling methods. Finally, an application is briefly discussed comparing the performance of the particle filter designs with classical nonlinear filter implementations.
Predicting speech intelligibility in conditions with nonlinearly processed noisy speech
DEFF Research Database (Denmark)
Jørgensen, Søren; Dau, Torsten
2013-01-01
The speech-based envelope power spectrum model (sEPSM; [1]) was proposed in order to overcome the limitations of the classical speech transmission index (STI) and speech intelligibility index (SII). The sEPSM applies the signal-tonoise ratio in the envelope domain (SNRenv), which was demonstrated...... to successfully predict speech intelligibility in conditions with nonlinearly processed noisy speech, such as processing with spectral subtraction. Moreover, a multiresolution version (mr-sEPSM) was demonstrated to account for speech intelligibility in various conditions with stationary and fluctuating...... from computational auditory scene analysis and further support the hypothesis that the SNRenv is a powerful metric for speech intelligibility prediction....
Nonlinear Stability of a SIRS Epidemic Model with Convex Incidence Rate
Buonomo, B.; Rionero, S.
2010-09-01
We study an epidemic model for infections with non permanent acquired immunity (SIRS). The incidence rate is assumed to be convex respect to the infective class. By using a peculiar Lyapunov function, we obtain necessary and sufficient conditions for the local nonlinear stability of equilibria. Conditions ensuring the global stability of the endemic equilibrium are also obtained. Our procedure allows to enlarge the class of incidence rates ensuring the Lyapunov nonlinear stability of the endemic equilibrium for SIRS models.
Ge, Hao; Qian, Hong
2017-01-01
This paper studies a mathematical formalism of nonequilibrium thermodynamics for chemical reaction models with N species, M reactions, and general rate law. We establish a mathematical basis for J. W. Gibbs' macroscopic chemical thermodynamics under G. N. Lewis' kinetic law of entire equilibrium (detailed balance in nonlinear chemical kinetics). In doing so, the equilibrium thermodynamics is then naturally generalized to nonequilibrium settings without detailed balance. The kinetic models are represented by a Markovian jumping process. A generalized macroscopic chemical free energy function and its associated balance equation with nonnegative source and sink are the major discoveries. The proof is based on the large deviation principle of this type of Markov processes. A general fluctuation dissipation theorem for stochastic reaction kinetics is also proved. The mathematical theory illustrates how a novel macroscopic dynamic law can emerges from the mesoscopic kinetics in a multi-scale system.
Wu, Hao; Noé, Frank
2011-03-01
Diffusion processes are relevant for a variety of phenomena in the natural sciences, including diffusion of cells or biomolecules within cells, diffusion of molecules on a membrane or surface, and diffusion of a molecular conformation within a complex energy landscape. Many experimental tools exist now to track such diffusive motions in single cells or molecules, including high-resolution light microscopy, optical tweezers, fluorescence quenching, and Förster resonance energy transfer (FRET). Experimental observations are most often indirect and incomplete: (1) They do not directly reveal the potential or diffusion constants that govern the diffusion process, (2) they have limited time and space resolution, and (3) the highest-resolution experiments do not track the motion directly but rather probe it stochastically by recording single events, such as photons, whose properties depend on the state of the system under investigation. Here, we propose a general Bayesian framework to model diffusion processes with nonlinear drift based on incomplete observations as generated by various types of experiments. A maximum penalized likelihood estimator is given as well as a Gibbs sampling method that allows to estimate the trajectories that have caused the measurement, the nonlinear drift or potential function and the noise or diffusion matrices, as well as uncertainty estimates of these properties. The approach is illustrated on numerical simulations of FRET experiments where it is shown that trajectories, potentials, and diffusion constants can be efficiently and reliably estimated even in cases with little statistics or nonequilibrium measurement conditions.
McNaughton, B H; Kopelman, R; Agayan, Rodney R.; Kopelman, Raoul; Naughton, Brandon H. Mc
2006-01-01
We report on a new technique which was used to detect single Escherichia coli that is based on the changes in the nonlinear rotation of a magnetic microsphere driven by an external magnetic field. The presence of one Escherichia Coli bacterium on the surface of a 2.0 micron magnetic microsphere caused an easily measurable change in the drag of the system and, therefore, in the nonlinear rotation rate. The straight-forward measurement uses standard microscopy techniques and the observed average shift in the nonlinear rotation rate changed by a factor of ~3.8.
Nonlinear Pulse Shaping in Fibres for Pulse Generation and Optical Processing
Directory of Open Access Journals (Sweden)
Sonia Boscolo
2012-01-01
Full Text Available The development of new all-optical technologies for data processing and signal manipulation is a field of growing importance with a strong potential for numerous applications in diverse areas of modern science. Nonlinear phenomena occurring in optical fibres have many attractive features and great, but not yet fully explored, potential in signal processing. Here, we review recent progress on the use of fibre nonlinearities for the generation and shaping of optical pulses and on the applications of advanced pulse shapes in all-optical signal processing. Amongst other topics, we will discuss ultrahigh repetition rate pulse sources, the generation of parabolic shaped pulses in active and passive fibres, the generation of pulses with triangular temporal profiles, and coherent supercontinuum sources. The signal processing applications will span optical regeneration, linear distortion compensation, optical decision at the receiver in optical communication systems, spectral and temporal signal doubling, and frequency conversion.
Nonlinear processes in the strong wave-plasma interaction
Pegoraro, Francesco; Califano, Francesco; Attico, Nicola; Bulanov, Sergei
2000-10-01
Nonlinear interactions in hot laboratory and/or astrophysical plasmas are a very efficient mechanism able to transfer the energy from the large to the small spatial scales of the system. As a result, kinetic processes are excited and play a key role in the plasma dynamics since the typical fluid dissipative length scales (where the nonlinear cascade is stopped) are (much) smaller then the kinetic length scales. Then, the key point is the role of the kinetic effects in the global plasma dynamics, i.e. whether the kinetic effects remains confined to the small scales of the system or whether there is a significant feedback on the large scales. Here we will address this problem by discussing the nonlinear kinetic evolution of the electromagnetic beam plasma instability where phase space vortices, as well as large scale vortex like magnetic structures in the physical space, are generated by wave - particle interactions. The role and influence of kinetic effects on the large scale plasma dynamics will be also discussed by addressing the problem of collisionless magnetic reconection.
Recent Advances in Graphene-Assisted Nonlinear Optical Signal Processing
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Jian Wang
2016-01-01
Full Text Available Possessing a variety of remarkable optical, electronic, and mechanical properties, graphene has emerged as an attractive material for a myriad of optoelectronic applications. The wonderful optical properties of graphene afford multiple functions of graphene based polarizers, modulators, transistors, and photodetectors. So far, the main focus has been on graphene based photonics and optoelectronics devices. Due to the linear band structure allowing interband optical transitions at all photon energies, graphene has remarkably large third-order optical susceptibility χ(3, which is only weakly dependent on the wavelength in the near-infrared frequency range. The graphene-assisted four-wave mixing (FWM based wavelength conversions have been experimentally demonstrated. So, we believe that the potential applications of graphene also lie in nonlinear optical signal processing, where the combination of its unique large χ(3 nonlinearities and dispersionless over the wavelength can be fully exploited. In this review article, we give a brief overview of our recent progress in graphene-assisted nonlinear optical device and their applications, including degenerate FWM based wavelength conversion of quadrature phase-shift keying (QPSK signal, phase conjugated wavelength conversion by degenerate FWM and transparent wavelength conversion by nondegenerate FWM, two-input and three-input high-base optical computing, and high-speed gate-tunable terahertz coherent perfect absorption (CPA using a split-ring graphene.
Directory of Open Access Journals (Sweden)
Hyun-Seob Song
2013-09-01
Full Text Available The nonlinear behavior of metabolic systems can arise from at least two different sources. One comes from the nonlinear kinetics of chemical reactions in metabolism and the other from nonlinearity associated with regulatory processes. Consequently, organisms at a constant growth rate (as experienced in a chemostat could display multiple metabolic states or display complex oscillatory behavior both with potentially serious implications to process operation. This paper explores the nonlinear behavior of a metabolic model of Escherichia coli growth on mixed substrates with sufficient detail to include regulatory features through the cybernetic postulate that metabolic regulation is the consequence of a dynamic objective function ensuring the organism’s survival. The chief source of nonlinearity arises from the optimal formulation with the metabolic state determined by a convex combination of reactions contributing to the objective function. The model for anaerobic growth of E. coli was previously examined for multiple steady states in a chemostat fed by a mixture of glucose and pyruvate substrates under very specific conditions and experimentally verified. In this article, we explore the foregoing model for nonlinear behavior over the full range of parameters, γ (the fractional concentration of glucose in the feed mixture and D (the dilution rate. The observed multiplicity is in the cybernetic variables combining elementary modes. The results show steady-state multiplicity up to seven. No Hopf bifurcation was encountered, however. Bifurcation analysis of cybernetic models is complicated by the non-differentiability of the cybernetic variables for enzyme activities. A methodology is adopted here to overcome this problem, which is applicable to more complicated metabolic networks.
Directory of Open Access Journals (Sweden)
Juan Bolea
2016-11-01
Full Text Available The purpose of this study is to characterize and attenuate the influence of mean heart rate (HR on nonlinear heart rate variability (HRV indices (correlation dimension, sample and approximate entropy as a consequence of being the HR the intrinsic sampling rate of HRV signal. This influence can notably alter nonlinear HRV indices and lead to biased information regarding autonomic nervous system (ANS modulation.First, a simulation study was carried out to characterize the dependence of nonlinear HRV indices on HR assuming similar ANS modulation. Second, two HR-correction approaches were proposed: one based on regression formulas and another one based on interpolating RR time series. Finally, standard and HR-corrected HRV indices were studied in a body position change database.The simulation study showed the HR-dependence of non-linear indices as a sampling rate effect, as well as the ability of the proposed HR-corrections to attenuate mean HR influence. Analysis in a body position changes database shows that correlation dimension was reduced around 21% in median values in standing with respect to supine position (p < 0.05, concomitant with a 28% increase in mean HR (p < 0.05. After HR-correction, correlation dimension decreased around 18% in standing with respect to supine position, being the decrease still significant. Sample and approximate entropy showed similar trends.HR-corrected nonlinear HRV indices could represent an improvement in their applicability as markers of ANS modulation when mean HR changes.
Institute of Scientific and Technical Information of China (English)
XU Guang; QIAN Liejia; WANG Tao; FAN Dianyuan; LI Fuming
2004-01-01
It is shown that the cascaded fifth-order nonlinear phase shifts will increase with energy loss in the cascaded processes. Essentially different from the multi-photon absorption accompanied with inherent material nonlinearities, the loss of fundamental wave in a cascaded process is controllable and suppressible. By introducing difference frequencies generated from the reaction between the fundamental and its second harmonic after the cascaded processes, the fundamental wave can be free of energy loss, while the large cascaded fifth-order nonlinear phase shift is maintained.
Martin, J; Schneider, F; Kowalewskij, A; Jordan, D; Hapfelmeier, A; Kochs, E F; Wagner, K J; Schulz, C M
2016-12-01
Excessive workload may impact the anaesthetists' ability to adequately process information during clinical practice in the operation room and may result in inaccurate situational awareness and performance. This exploratory study investigated heart rate (HR), linear and non-linear heart rate variability (HRV) metrics and subjective ratings scales for the assessment of workload associated with the anaesthesia stages induction, maintenance and emergence. HR and HRV metrics were calculated based on five min segments from each of the three anaesthesia stages. The area under the receiver operating characteristics curve (AUC) of the investigated metrics was calculated to assess their ability to discriminate between the stages of anaesthesia. Additionally, a multiparametric approach based on logistic regression models was performed to further evaluate whether linear or non-linear heart rate metrics are suitable for the assessment of workload. Mean HR and several linear and non-linear HRV metrics including subjective workload ratings differed significantly between stages of anaesthesia. Permutation Entropy (PeEn, AUC=0.828) and mean HR (AUC=0.826) discriminated best between the anaesthesia stages induction and maintenance. In the multiparametric approach using logistic regression models, the model based on non-linear heart rate metrics provided a higher AUC compared with the models based on linear metrics. In this exploratory study based on short ECG segment analysis, PeEn and HR seem to be promising to separate workload levels between different stages of anaesthesia. The multiparametric analysis of the regression models favours non-linear heart rate metrics over linear metrics. © The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Exchange Rates and Monetary Fundamentals: What Do We Learn from Linear and Nonlinear Regressions?
Directory of Open Access Journals (Sweden)
Guangfeng Zhang
2014-01-01
Full Text Available This paper revisits the association between exchange rates and monetary fundamentals with the focus on both linear and nonlinear approaches. With the monthly data of Euro/US dollar and Japanese yen/US dollar, our linear analysis demonstrates the monetary model is a long-run description of exchange rate movements, and our nonlinear modelling suggests the error correction model describes the short-run adjustment of deviations of exchange rates, and monetary fundamentals are capable of explaining exchange rate dynamics under an unrestricted framework.
Nonlinear Optical Microscopy Signal Processing Strategies in Cancer
Adur, Javier; Carvalho, Hernandes F; Cesar, Carlos L; Casco, Víctor H
2014-01-01
This work reviews the most relevant present-day processing methods used to improve the accuracy of multimodal nonlinear images in the detection of epithelial cancer and the supporting stroma. Special emphasis has been placed on methods of non linear optical (NLO) microscopy image processing such as: second harmonic to autofluorescence ageing index of dermis (SAAID), tumor-associated collagen signatures (TACS), fast Fourier transform (FFT) analysis, and gray level co-occurrence matrix (GLCM)-based methods. These strategies are presented as a set of potential valuable diagnostic tools for early cancer detection. It may be proposed that the combination of NLO microscopy and informatics based image analysis approaches described in this review (all carried out on free software) may represent a powerful tool to investigate collagen organization and remodeling of extracellular matrix in carcinogenesis processes. PMID:24737930
Forecasting RMB Exchange Rate Based on a Nonlinear Combination Model of ARFIMA, SVM, and BPNN
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Chi Xie
2015-01-01
Full Text Available There are various models to predict financial time series like the RMB exchange rate. In this paper, considering the complex characteristics of RMB exchange rate, we build a nonlinear combination model of the autoregressive fractionally integrated moving average (ARFIMA model, the support vector machine (SVM model, and the back-propagation neural network (BPNN model to forecast the RMB exchange rate. The basic idea of the nonlinear combination model (NCM is to make the prediction more effective by combining different models’ advantages, and the weight of the combination model is determined by a nonlinear weighted mechanism. The RMB exchange rate against US dollar (RMB/USD and the RMB exchange rate against Euro (RMB/EUR are used as the empirical examples to evaluate the performance of NCM. The results show that the prediction performance of the nonlinear combination model is better than the single models and the linear combination models, and the nonlinear combination model is suitable for the prediction of the special time series, such as the RMB exchange rate.
A simple nonlinear PD controller for integrating processes.
Dey, Chanchal; Mudi, Rajani K; Simhachalam, Dharmana
2014-01-01
Many industrial processes are found to be integrating in nature, for which widely used Ziegler-Nichols tuned PID controllers usually fail to provide satisfactory performance due to excessive overshoot with large settling time. Although, IMC (Internal Model Control) based PID controllers are capable to reduce the overshoot, but little improvement is found in the load disturbance response. Here, we propose an auto-tuning proportional-derivative controller (APD) where a nonlinear gain updating factor α continuously adjusts the proportional and derivative gains to achieve an overall improved performance during set point change as well as load disturbance. The value of α is obtained by a simple relation based on the instantaneous values of normalized error (eN) and change of error (ΔeN) of the controlled variable. Performance of the proposed nonlinear PD controller (APD) is tested and compared with other PD and PID tuning rules for pure integrating plus delay (IPD) and first-order integrating plus delay (FOIPD) processes. Effectiveness of the proposed scheme is verified on a laboratory scale servo position control system.
Sun, Dajun D; Lee, Ping I
2015-04-06
The importance of rate of supersaturation generation on the kinetic solubility profiles of amorphous systems has recently been shown by us; however, the previous focus was limited to constant rates of supersaturation generation. The objective of the current study is to further examine the effect of nonlinear rate profiles of supersaturation generation in amorphous systems, including (1) instantaneous or infinite rate (i.e., initial degree of supersaturation), (2) first-order rate (e.g., from dissolution of amorphous drug particles), and (3) matrix diffusion regulated rate (e.g., drug release from amorphous solid dispersions (ASDs) based on cross-linked poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels), on the kinetic solubility profiles of a model poorly soluble drug indomethacin (IND) under nonsink dissolution conditions. The previously established mechanistic model taking into consideration both the crystal growth and ripening processes was extended to predict the evolution of supersaturation resulting from nonlinear rates of supersaturation generation. Our results confirm that excessively high initial supersaturation or a rapid supersaturation generation leads to a surge in maximum supersaturation followed by a rapid decrease in drug concentration owing to supersaturation-induced precipitation; however, an exceedingly low degree of supersaturation or a slow rate of supersaturation generation does not sufficiently raise the supersaturation level, which results in a lower but broader maximum kinetic solubility profile. Our experimental data suggest that an optimal area-under-the-curve of the kinetic solubility profiles exists at an intermediate initial supersaturation level for the amorphous systems studied here, which agrees well with the predicted trend. Our model predictions also support our experimental findings that IND ASD in cross-linked PHEMA exhibits a unique kinetic solubility profile because the resulting supersaturation level is governed by a matrix
Study on Rail Profile Optimization Based on the Nonlinear Relationship between Profile and Wear Rate
Directory of Open Access Journals (Sweden)
Jianxi Wang
2017-01-01
Full Text Available This paper proposes a rail profile optimization method that takes account of wear rate within design cycle so as to minimize rail wear at the curve in heavy haul railway and extend the service life of rail. Taking rail wear rate as the object function, the vertical coordinate of rail profile at range optimization as independent variable, and the geometric characteristics and grinding depth of rail profile as constraint conditions, the support vector machine regression theory was used to fit the nonlinear relationship between rail profile and its wear rate. Then, the profile optimization model was built. Based on the optimization principle of genetic algorithm, the profile optimization model was solved to achieve the optimal rail profile. A multibody dynamics model was used to check the dynamic performance of carriage running on optimal rail profile. The result showed that the average relative error of support vector machine regression model remained less than 10% after a number of training processes. The dynamic performance of carriage running on optimized rail profile met the requirements on safety index and stability. The wear rate of optimized profile was lower than that of standard profile by 5.8%; the allowable carrying gross weight increased by 12.7%.
Results on stabilization of nonlinear systems under finite data-rate constraints
Persis, Claudio De
2004-01-01
We discuss in this paper a result concerning the stabilization problem of nonlinear systems under data-rate constraints using output feedback. To put the result in a broader context, we shall first review a number of recent contributions on the stabilization problem under data-rate constraints when
Soft Sensor for Inputs and Parameters Using Nonlinear Singular State Observer in Chemical Processes
Institute of Scientific and Technical Information of China (English)
许锋; 汪晔晔; 罗雄麟
2013-01-01
Chemical processes are usually nonlinear singular systems. In this study, a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes, which are augmented as state variables. Based on the observability of the singular system, this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters. When the observability is satisfied, the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer. The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation. With the catalyst circulation rate as the only unknown input without model error, one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst cir-culation rate. However, when uncertain model parameters also exist, additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes.
Processing Speed, Speech Rate, and Memory.
Kail, Robert
1992-01-01
The memory, processing speed, and articulation rate of 24 9 year olds and 24 adults were measured. Results supported a model in which individuals execute cognitive processes more rapidly as they grow older. In addition, age contributes to more rapid rehearsal of words, which yields more accurate recall. (BG)
Detailed discussion of the optimum baud rate of nonlinearity in WDM transmission
Wang, Wanli; Qiao, Yaojun; Yang, Lin
2017-01-01
Different numbers of sub-channels correspond to different baud rates per sub-channel when the total baud rate is fixed. The optimum baud rate of nonlinearity in WDM systems is investigated in this paper. We find that the phase matching effect produces an optimum baud rate of nonlinearity, which is related to the chromatic dispersion accumulation of a single span. Then other factors that influence the optimum baud rate are analyzed. By mathematical derivation and simulation verification, larger number of spans and larger spectrum gap between sub-channels both make the optimum value decrease. We also find that different modulation formats barely change the optimum baud rate if other system settings are the same and all sub-channels have the same modulation format.
Nonlinear calibration and data processing of the solar radio burst
Institute of Scientific and Technical Information of China (English)
颜毅华; 谭程明; 徐龙; 姬慧荣; 傅其骏; 宋国乡
2002-01-01
The processes of the sudden energy release and energy transfer, and particle accelerations are the most challenge fundamental problems in solar physics as well as in astrophysics. Nowadays, there has been no direct measurement of the plasma parameters and magnetic fields at the coronal energy release site. Under the certain hypothesis of radiation mechanism and transmission process, radio measurement is almost the only method to diagnose coronal magnetic field. The broadband dynamic solar radio spectrometer that has been finished recently in China has higher time and frequency resolutions. Thus it plays an important role during the research of the 23rd solar cycle in China. Sometimes when there were very large bursts, the spectrometer will be overflowed. It needs to take some special process to discriminate the instrument and interference effects from solar burst signals. According to the characteristic of the solar radio broadband dynamic spectrometer, we developed a nonlinear calibration method to deal with the overflow of instrument, and introduced channel-modification method to deal with images. Finally the interference is eliminated with the help of the wavelet method. Here we take the analysis of the well-known solar-terrestrial event on July 14th, 2000 as the example. It shows the feasibility and validity of the method mentioned above. These methods can also be applied to other issues.
Effects of breathing patterns and light exercise on linear and nonlinear heart rate variability.
Weippert, Matthias; Behrens, Kristin; Rieger, Annika; Kumar, Mohit; Behrens, Martin
2015-08-01
Despite their use in cardiac risk stratification, the physiological meaning of nonlinear heart rate variability (HRV) measures is not well understood. The aim of this study was to elucidate effects of breathing frequency, tidal volume, and light exercise on nonlinear HRV and to determine associations with traditional HRV indices. R-R intervals, blood pressure, minute ventilation, breathing frequency, and respiratory gas concentrations were measured in 24 healthy male volunteers during 7 conditions: voluntary breathing at rest, and metronome guided breathing (0.1, 0.2 and 0.4 Hz) during rest, and cycling, respectively. The effect of physical load was significant for heart rate (HR; p effect of load and breathing pattern was evident. Correlations to traditional HRV indices were modest (r from -0.14 to -0.67, p exercise does not significantly affect short-time HRV nonlinear indices, respiratory activity has to be considered as a potential contributor at rest and during light dynamic exercise.
Geometry effect on energy transfer rate in a coupled-quantum-well structure: nonlinear regime
Salavati-fard, T.; Vazifehshenas, T.
2014-12-01
We study theoretically the effect of geometry on the energy transfer rate at nonlinear regime in a coupled-quantum-well system using the balance equation approach. To investigate comparatively the effect of both symmetric and asymmetric geometry, different structures are considered. The random phase approximation dynamic dielectric function is employed to include the contributions from both quasiparticle and plasmon excitations. Also, the short-range exchange interaction is taken into account through the Hubbard approximation. Our numerical results show that the energy transfer rate increases by increasing the well thicknesses in symmetric structures. Furthermore, by increasing spatial asymmetry, the energy transfer rate decreases for the electron temperature range of interest. From numerical calculations, it is obtained that the nonlinear energy transfer rate is proportional to the square of electron drift velocity in all structures and also, found that the influence of Hubbard local field correction on the energy transfer rate gets weaker by increasing the strength of applied electric field.
Nonlinear closure relations theory for transport processes in nonequilibrium systems.
Sonnino, Giorgio
2009-05-01
A decade ago, a macroscopic theory for closure relations has been proposed for systems out of Onsager's region. This theory is referred to as the thermodynamic field theory (TFT). The aim of this work was to determine the nonlinear flux-force relations that respect the thermodynamic theorems for systems far from equilibrium. We propose a formulation of the TFT where one of the basic restrictions, namely, the closed-form solution for the skew-symmetric piece of the transport coefficients, has been removed. In addition, the general covariance principle is replaced by the De Donder-Prigogine thermodynamic covariance principle (TCP). The introduction of TCP requires the application of an appropriate mathematical formalism, which is referred to as the entropy-covariant formalism. By geometrical arguments, we prove the validity of the Glansdorff-Prigogine universal criterion of evolution. A new set of closure equations determining the nonlinear corrections to the linear ("Onsager") transport coefficients is also derived. The geometry of the thermodynamic space is non-Riemannian. However, it tends to be Riemannian for high values of the entropy production. In this limit, we recover the transport equations found by the old theory. Applications of our approach to transport in magnetically confined plasmas, materials submitted to temperature, and electric potential gradients or to unimolecular triangular chemical reactions can be found at references cited herein. Transport processes in tokamak plasmas are of particular interest. In this case, even in the absence of turbulence, the state of the plasma remains close to (but, it is not in) a state of local equilibrium. This prevents the transport relations from being linear.
Quantum mechanics of molecular rate processes
Levine, Raphael D
1999-01-01
This survey of applications of the theory of collisions and rate processes to molecular problems explores collisions of molecules with internal structure, generalized Ehrenfest theorem, theory of reactive collisions, and role of symmetry. It also reviews partitioning technique, equivalent potentials and quasibound states, theory of direct reactions, more. 1969 edition.
Nonlinear analysis of heart rate variability in patients with eating disorders
Vigo, Daniel E.; Castro, Mariana N.; Dorpinghaus, Andrea; Weidema, Hylke; Cardinali, Daniel P.; Siri, Leonardo Nicola; Rovira, Bernardo; Fahrer, Rodolfo D.; Nogues, Martin; Leiguarda, Ramon C.; Guinjoan, Salvador M.
2008-01-01
Patients with anorexia nervosa or bulimia nervosa often have signs of autonomic dysfunction potentially deleterious to the heart. The aim of this study was to ascertain the nonlinear properties of heart rate variability in patients with eating disorders. A group of 33 women with eating disorders (14
Minimal data rate stabilization of nonlinear systems over networks with large delays
Persis, Claudio De
2007-01-01
We consider the problem of designing encoders, decoders and controllers which stabilize feedforward nonlinear systems over a communication network with finite bandwidth and large delay. The control scheme guarantees minimal data-rate semi-global asymptotic and local exponential stabilizatioln of the
The Nonlinear Dynamic Relationship of Exchange Rates: Parametric and Nonparametric Causality testing
Bekiros, S.D.; Diks, C.
2007-01-01
The present study investigates the long-term linear and nonlinear causal linkages among six currencies, namely EUR/USD, GBP/USD, USD/JPY, USD/CHF, AUD/USD and USD/CAD. The prime motivation for choosing these exchange rates comes from the fact that they are the most liquid and widely traded, covering
Nonlinear analysis of heart rate variability in patients with eating disorders
Vigo, Daniel E.; Castro, Mariana N.; Dorpinghaus, Andrea; Weidema, Hylke; Cardinali, Daniel P.; Siri, Leonardo Nicola; Rovira, Bernardo; Fahrer, Rodolfo D.; Nogues, Martin; Leiguarda, Ramon C.; Guinjoan, Salvador M.
2008-01-01
Patients with anorexia nervosa or bulimia nervosa often have signs of autonomic dysfunction potentially deleterious to the heart. The aim of this study was to ascertain the nonlinear properties of heart rate variability in patients with eating disorders. A group of 33 women with eating disorders (14
Nonlinear properties of and nonlinear processing in hydrogenated amorphous silicon waveguides
DEFF Research Database (Denmark)
Kuyken, B.; Ji, Hua; Clemmen, S.
2011-01-01
We propose hydrogenated amorphous silicon nanowires as a platform for nonlinear optics in the telecommunication wavelength range. Extraction of the nonlinear parameter of these photonic nanowires reveals a figure of merit larger than 2. It is observed that the nonlinear optical properties...... of these waveguides degrade with time, but that this degradation can be reversed by annealing the samples. A four wave mixing conversion efficiency of + 12 dB is demonstrated in a 320 Gbit/s serial optical waveform data sampling experiment in a 4 mm long photonic nanowire....
Nonlinear quantum electrodynamic and electroweak processes in strong laser fields
Energy Technology Data Exchange (ETDEWEB)
Meuren, Sebastian
2015-06-24
Various nonlinear electrodynamic and electroweak processes in strong plane-wave laser fields are considered with an emphasis on short-pulse effects. In particular, the momentum distribution of photoproduced electron-positron pairs is calculated numerically and a semiclassical interpretation of its characteristic features is established. By proving the optical theorem, compact double-integral expressions for the total pair-creation probability are obtained and numerically evaluated. The exponential decay of the photon wave function in a plane wave is included by solving the Schwinger-Dyson equations to leading-order in the quasistatic approximation. In this respect, the polarization operator in a plane wave is investigated and its Ward-Takahashi identity verified. A classical analysis indicates that a photoproduced electron-positron pair recollides for certain initial conditions. The contributions of such recollision processes to the polarization operator are identified and calculated both analytically and numerically. Furthermore, the existence of nontrivial electron-spin dynamics induced by quantum fluctuations is verified for ultra-short laser pulses. Finally, the exchange of weak gauge bosons is considered, which is essential for neutrino-photon interactions. In particular, the axial-vector-vector coupling tensor is calculated and the so-called Adler-Bell-Jackiw (ABJ) anomaly investigated.
Convergence rates for dispersive approximation schemes to nonlinear Schr\\"odinger equations
Ignat, Liviu I
2011-01-01
This article is devoted to the analysis of the convergence rates of several numerical approximation schemes for linear and nonlinear Schr\\"odinger equations on the real line. Recently, the authors have introduced viscous and two-grid numerical approximation schemes that mimic at the discrete level the so-called Strichartz dispersive estimates of the continuous Schr\\"odinger equation. This allows to guarantee the convergence of numerical approximations for initial data in L2(R), a fact that can not be proved in the nonlinear setting for standard conservative schemes unless more regularity of the initial data is assumed. In the present article we obtain explicit convergence rates and prove that dispersive schemes fulfilling the Strichartz estimates are better behaved for H^s(R) data if 0 < s < 1/2. Indeed, while dispersive schemes ensure a polynomial convergence rate, non-dispersive ones only yield logarithmic decay rates.
All-optical signal processing in quadratic nonlinear materials
DEFF Research Database (Denmark)
Johansen, Steffen Kjær
2002-01-01
of materials with a second order nonlinearity, the so-called X(2) materials, is faster and stronger than that of more conventional materials with a cubic nonlinearity. The X(2) materials support spatial solitons consisting of two coupled components, the fundamental wave (FW) and its second harmonic (SH......). During this project the interaction between such spatial solitons has been investigated theoretically through perturbation theory and experimentally via numerical simulations. The outcome of this research isnew theoretical tools for quantitatively predicting the escape angle, i.e. the angle of incidence...... and exploitation of these cubic nonlinearities in two-period QPM wave-guides has been another area of investigation. Introducing the second period might make practical engineering of the nonlinearities possible. A major result is the discovery that cubic nonlinearities leads to an enhancement of the bandwidth...
Sajedi, Salar; Kamal Asl, Alireza; Ay, Mohammad R; Farahani, Mohammad H; Rahmim, Arman
2013-06-01
Applications in imaging and spectroscopy rely on pulse processing methods for appropriate data generation. Often, the particular method utilized does not highly impact data quality, whereas in some scenarios, such as in the presence of high count rates or high frequency pulses, this issue merits extra consideration. In the present study, a new approach for pulse processing in nuclear medicine imaging and spectroscopy is introduced and evaluated. The new non-linear recursive filter (NLRF) performs nonlinear processing of the input signal and extracts the main pulse characteristics, having the powerful ability to recover pulses that would ordinarily result in pulse pile-up. The filter design defines sampling frequencies lower than the Nyquist frequency. In the literature, for systems involving NaI(Tl) detectors and photomultiplier tubes (PMTs), with a signal bandwidth considered as 15 MHz, the sampling frequency should be at least 30 MHz (the Nyquist rate), whereas in the present work, a sampling rate of 3.3 MHz was shown to yield very promising results. This was obtained by exploiting the known shape feature instead of utilizing a general sampling algorithm. The simulation and experimental results show that the proposed filter enhances count rates in spectroscopy. With this filter, the system behaves almost identically as a general pulse detection system with a dead time considerably reduced to the new sampling time (300 ns). Furthermore, because of its unique feature for determining exact event times, the method could prove very useful in time-of-flight PET imaging.
Hooker, John C.
1990-01-01
A preliminary study of the applicability of nonlinear dynamic systems analysis techniques to low body negative pressure (LBNP) studies. In particular, the applicability of the heart rate delay map is investigated. It is suggested that the heart rate delay map has potential as a supplemental tool in the assessment of subject performance in LBNP tests and possibly in the determination of susceptibility to cardiovascular deconditioning with spaceflight.
What do we know about real exchange rate non-linearities?
DEFF Research Database (Denmark)
Kruse, Robinson; Frömmel, Michael; Menkhoff, Lukas;
This research points to the serious problem of potentially misspecified alternative hypotheses when testing for unit roots in real exchange rates. We apply a popular unit root test against nonlinear ESTAR and develop a Markov Switching unit root test. The empirical power of these tests against co...... model performs clearly better. An empirical application of these tests suggests that real exchange rates may indeed be explained by Markov-Switching dynamics....
Non-linear and scale-invariant analysis of the Heart Rate Variability
Kalda, J; Vainu, M; Laan, M
2003-01-01
Human heart rate fluctuates in a complex and non-stationary manner. Elaborating efficient and adequate tools for the analysis of such signals has been a great challenge for the researchers during last decades. Here, an overview of the main research results in this field is given. The following question are addressed: (a) what are the intrinsic features of the heart rate variability signal; (b) what are the most promising non-linear measures, bearing in mind clinical diagnostic and prognostic applications.
Nonlinear Optical Signal Processing for Tbit/s Ethernet Applications
DEFF Research Database (Denmark)
Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen;
2012-01-01
We review recent experimental demonstrations of Tbaud optical signal processing. In particular, we describe a successful 1.28 Tbit/s serial data generation based on single polarization 1.28 Tbaud symbol rate pulses with binary data modulation (OOK) and subsequent all-optical demultiplexing. We also...
Institute of Scientific and Technical Information of China (English)
LIN Xiangguo; LIANG Yong
2005-01-01
The processing of nonlinear data was one of hot topics in surveying and mapping field in recent years.As a result, many linear methods and nonlinear methods have been developed.But the methods for processing generalized nonlinear surveying and mapping data, especially for different data types and including unknown parameters with random or nonrandom, are seldom noticed.A new algorithm model is presented in this paper for processing nonlinear dynamic multiple-period and multiple-accuracy data derived from deformation monitoring network.
Parazzini, Marta; Ravazzani, Paolo; Thuroczy, György; Molnar, Ferenc B; Ardesi, Gianluca; Sacchettini, Alessio; Mainardi, Luca Tommaso
2013-06-01
This study was designed to assess the nonlinear dynamics of heart rate variability (HRV) during exposure to low-intensity EMFs. Twenty-six healthy young volunteers were subjected to a rest-to-stand protocol to evaluate autonomic nervous system in quiet condition (rest, vagal prevalence) and after a sympathetic activation (stand). The procedure was conducted twice in a double-blind design: once with a genuine EMFs exposure (GSM cellular phone at 900 MHz, 2 W) and once with a sham exposure (at least 24 h apart). During each session, three-lead electrocardiograms were recorded and RR series extracted off-line. The RR series were analyzed by nonlinear deterministic techniques in every phase of the protocol and during the different exposures. The analysis of the data shows there was no statistically significant effect due to GSM exposure on the nonlinear dynamics of HRV.
Measurement of heart rate variability by methods based on nonlinear dynamics.
Huikuri, Heikki V; Mäkikallio, Timo H; Perkiömäki, Juha
2003-01-01
Heart rate (HR) variability has been conventionally analyzed with time and frequency domain methods, which measure the overall magnitude of R-R interval fluctuations around its mean value or the magnitude of fluctuations in some predetermined frequencies. Analysis of HR dynamics by methods based on chaos theory and nonlinear system theory has gained recent interest. This interest is based on observations suggesting that the mechanisms involved in cardiovascular regulation likely interact with each other in a nonlinear way. Furthermore, recent observational studies suggest that some indexes describing nonlinear HR dynamics, such as fractal scaling exponents, may provide more powerful prognostic information than the traditional HR variability indexes. In particular, short-term fractal scaling exponent measured by detrended fluctuation analysis method has been shown to predict fatal cardiovascular events in various populations. Approximate entropy, a nonlinear index of HR dynamics, which describes the complexity of R-R interval behavior, has provided information on the vulnerability to atrial fibrillation. There are many other nonlinear indexes, eg, Lyapunov exponent and correlation dimensions, which also give information on the characteristics of HR dynamics, but their clinical utility is not well established. Although concepts of chaos theory, fractal mathematics, and complexity measures of HR behavior in relation to cardiovascular physiology or various cardiovascular events are still far away from clinical medicine, they are a fruitful area for future research to expand our knowledge concerning the behavior of cardiovascular oscillations in normal healthy conditions as well as in disease states.
1989-10-30
In this Phase I SBIR study, new methods are developed for the system identification and stochastic filtering of nonlinear controlled Markov processes...state space Markov process models and canonical variate analysis (CVA) for obtaining optimal nonlinear procedures for system identification and stochastic
Application of Novel Nonlinear Optical Materials to Optical Processing
Banerjee, Partha P.
1999-01-01
We describe wave mixing and interactions in nonlinear photorefractive polymers and disodium flourescein. Higher diffracted orders yielding forward phase conjugation can be generated in a two-wave mixing geometry in photorefractive polymers, and this higher order can be used for image edge enhancement and correlation. Four-wave mixing and phase conjugation is studied using nonlinear disodium floureschein, and the nature and properties of gratings written in this material are investigated.
Goldberg, Robert K.
2000-01-01
There has been no accurate procedure for modeling the high-speed impact of composite materials, but such an analytical capability will be required in designing reliable lightweight engine-containment systems. The majority of the models in use assume a linear elastic material response that does not vary with strain rate. However, for containment systems, polymer matrix composites incorporating ductile polymers are likely to be used. For such a material, the deformation response is likely to be nonlinear and to vary with strain rate. An analytical model has been developed at the NASA Glenn Research Center at Lewis Field that incorporates both of these features. A set of constitutive equations that was originally developed to analyze the viscoplastic deformation of metals (Ramaswamy-Stouffer equations) was modified to simulate the nonlinear, rate-dependent deformation of polymers. Specifically, the effects of hydrostatic stresses on the inelastic response, which can be significant in polymers, were accounted for by a modification of the definition of the effective stress. The constitutive equations were then incorporated into a composite micromechanics model based on the mechanics of materials theory. This theory predicts the deformation response of a composite material from the properties and behavior of the individual constituents. In this manner, the nonlinear, rate-dependent deformation response of a polymer matrix composite can be predicted.
Asymptotic solution of nonlinear moment equations for constant-rate aerosol reactors
Directory of Open Access Journals (Sweden)
B. D. Shaw
1998-01-01
Full Text Available Nonlinear evolution equations based upon moments of the aerosol size distribution function are solved asymptotically for constant-rate aerosol reactors (i.e., where condensible monomer is added at a constant rate operating in the free-molecular limit. The governing equations are nondimensionalized and a large parameter that controls nucleation behavior is identified. Asymptotic analyses are developed in terms of this parameter. Comparison of the asymptotic results with direct numerical integration of the governing equations is favorable. The asymptotic results provide a simplified analytical approach to estimating average particle sizes, particle number densities, and peak supersaturation values for constant-rate aerosol reactors.
Chen, Pang-Chia
2013-01-01
This paper investigates multi-objective controller design approaches for nonlinear boiler-turbine dynamics subject to actuator magnitude and rate constraints. System nonlinearity is handled by a suitable linear parameter varying system representation with drum pressure as the system varying parameter. Variation of the drum pressure is represented by suitable norm-bounded uncertainty and affine dependence on system matrices. Based on linear matrix inequality algorithms, the magnitude and rate constraints on the actuator and the deviations of fluid density and water level are formulated while the tracking abilities on the drum pressure and power output are optimized. Variation ranges of drum pressure and magnitude tracking commands are used as controller design parameters, determined according to the boiler-turbine's operation range.
Nonlinear Model Algorithmic Control of a pH Neutralization Process
Institute of Scientific and Technical Information of China (English)
ZOU Zhiyun; YU Meng; WANG Zhizhen; LIU Xinghong; GUO Yuqing; ZHANG Fengbo; GUO Ning
2013-01-01
Control of pH neutralization processes is challenging in the chemical process industry because of their inherent strong nonlinearity.In this paper,the model algorithmic control (MAC) strategy is extended to nonlinear processes using Hammerstein model that consists of a static nonlinear polynomial function followed in series by a linear impulse response dynamic element.A new nonlinear Hammerstein MAC algorithm (named NLH-MAC) is presented in detail.The simulation control results of a pH neutralization process show that NLH-MAC gives better control performance than linear MAC and the commonly used industrial nonlinear propotional plus integral plus derivative (PID) controller.Further simulation experiment demonstrates that NLH-MAC not only gives good control response,but also possesses good stability and robustness even with large modeling errors.
Fan, Kuangang; Zhang, Yan; Gao, Shujing; Wei, Xiang
2017-09-01
A class of SIR epidemic model with generalized nonlinear incidence rate is presented in this paper. Temporary immunity and stochastic perturbation are also considered. The existence and uniqueness of the global positive solution is achieved. Sufficient conditions guaranteeing the extinction and persistence of the epidemic disease are established. Moreover, the threshold behavior is discussed, and the threshold value R0 is obtained. We show that if R0 1, then the system remains permanent in the mean.
Non-linear direct effects of acid rain on leaf photosynthetic rate of terrestrial plants.
Dong, Dan; Du, Enzai; Sun, Zhengzhong; Zeng, Xuetong; de Vries, Wim
2017-09-12
Anthropogenic emissions of acid precursors have enhanced global occurrence of acid rain, especially in East Asia. Acid rain directly suppresses leaf function by eroding surface waxes and cuticle and leaching base cations from mesophyll cells, while the simultaneous foliar uptake of nitrates in rainwater may directly benefit leaf photosynthesis and plant growth, suggesting a non-linear direct effect of acid rain. By synthesizing data from literature on acid rain exposure experiments, we assessed the direct effects of acid rain on leaf photosynthesis across 49 terrestrial plants in China. Our results show a non-linear direct effect of acid rain on leaf photosynthetic rate, including a neutral to positive effect above pH 5.0 and a negative effect below that pH level. The acid rain sensitivity of leaf photosynthesis showed no significant difference between herbs and woody species below pH 5.0, but the impacts above that pH level were strongly different, resulting in a significant increase in leaf photosynthetic rate of woody species and an insignificant effect on herbs. Our analysis also indicates a positive effect of the molar ratio of nitric versus sulfuric acid in the acid solution on leaf photosynthetic rate. These findings imply that rainwater acidity and the composition of acids both affect the response of leaf photosynthesis and therefore result in a non-linear direct effect. Copyright © 2017 Elsevier Ltd. All rights reserved.
Femtosecond Fiber Lasers Based on Dissipative Processes for Nonlinear Microscopy
Wise, Frank W.
2012-01-01
Recent progress in the development of femtosecond-pulse fiber lasers with parameters appropriate for nonlinear microscopy is reviewed. Pulse-shaping in lasers with only normal-dispersion components is briefly described, and the performance of the resulting lasers is summarized. Fiber lasers based on the formation of dissipative solitons now offer performance competitive with that of solid-state lasers, but with the benefits of the fiber medium. Lasers based on self-similar pulse evolution in the gain section of a laser also offer a combination of short pulse duration and high pulse energy that will be attractive for applications in nonlinear bioimaging. PMID:23869163
Nonlinear effect of dispersal rate on spatial synchrony of predator-prey cycles.
Fox, Jeremy W; Legault, Geoffrey; Legault, Geoff; Vasseur, David A; Einarson, Jodie A
2013-01-01
Spatially-separated populations often exhibit positively correlated fluctuations in abundance and other population variables, a phenomenon known as spatial synchrony. Generation and maintenance of synchrony requires forces that rapidly restore synchrony in the face of desynchronizing forces such as demographic and environmental stochasticity. One such force is dispersal, which couples local populations together, thereby synchronizing them. Theory predicts that average spatial synchrony can be a nonlinear function of dispersal rate, but the form of the dispersal rate-synchrony relationship has never been quantified for any system. Theory also predicts that in the presence of demographic and environmental stochasticity, realized levels of synchrony can exhibit high variability around the average, so that ecologically-identical metapopulations might exhibit very different levels of synchrony. We quantified the dispersal rate-synchrony relationship using a model system of protist predator-prey cycles in pairs of laboratory microcosms linked by different rates of dispersal. Paired predator-prey cycles initially were anti-synchronous, and were subject to demographic stochasticity and spatially-uncorrelated temperature fluctuations, challenging the ability of dispersal to rapidly synchronize them. Mean synchrony of prey cycles was a nonlinear, saturating function of dispersal rate. Even extremely low rates of dispersal (systems are sufficient to generate and maintain synchrony of cyclic population dynamics, at least when environments are not too spatially heterogeneous.
2013-01-01
This book consists of twenty seven chapters, which can be divided into three large categories: articles with the focus on the mathematical treatment of non-linear problems, including the methodologies, algorithms and properties of analytical and numerical solutions to particular non-linear problems; theoretical and computational studies dedicated to the physics and chemistry of non-linear micro-and nano-scale systems, including molecular clusters, nano-particles and nano-composites; and, papers focused on non-linear processes in medico-biological systems, including mathematical models of ferments, amino acids, blood fluids and polynucleic chains.
Gómez-Polo, C.; Duque, J. G. S.; Knobel, M.
2004-07-01
The magnetoimpedance effect and its nonlinear terms are analysed for a (Co0.94Fe0.06)72.5Si12.5B15 amorphous wire. In order to enhance the nonlinear contribution the sample was previously subjected to current annealing (Joule heating) to induce a circumferential anisotropy. The effect of the application of a torsional strain on the nonlinear magnetoimpedance is analysed in terms of the torsional dependence of the magnetic permeability, evaluated through experimental circumferential hysteresis loops. The results obtained clearly confirm the direct correlation between the asymmetric circumferential magnetization process and the occurrence of nonlinear second-harmonic terms in the magnetoimpedance voltage.
An SIR Epidemic Model with Time Delay and General Nonlinear Incidence Rate
Directory of Open Access Journals (Sweden)
Mingming Li
2014-01-01
Full Text Available An SIR epidemic model with nonlinear incidence rate and time delay is investigated. The disease transmission function and the rate that infected individuals recovered from the infected compartment are assumed to be governed by general functions F(S,I and G(I, respectively. By constructing Lyapunov functionals and using the Lyapunov-LaSalle invariance principle, the global asymptotic stability of the disease-free equilibrium and the endemic equilibrium is obtained. It is shown that the global properties of the system depend on both the properties of these general functions and the basic reproductive number R0.
Kur'yanova, E V; Teplyi, D L; Zhukova, Yu D; Zhukovina, N V
2015-12-01
The basic behavioral activity of nonlinear rats was evaluated from the sum of crossed peripheral and central squares and peripheral and central rearing postures in the open fi eld test. This index was low (30 episodes). Male rats with high score of orientation and exploratory activity were characterized by higher indexes of total heart rate variability than rats with low or intermediate activity. Specimens with a greater contribution of VLF waves into the total power spectrum of heart rate variability were shown to dominate among the rats with high behavioral activity. Our results are consistent with the notions of a suprasegmental nature of VLF waves.
Neural Generalized Predictive Control of a non-linear Process
DEFF Research Database (Denmark)
Sørensen, Paul Haase; Nørgård, Peter Magnus; Ravn, Ole
1998-01-01
qualities. The controller is a non-linear version of the well-known generalized predictive controller developed in linear control theory. It involves minimization of a cost function which in the present case has to be done numerically. Therefore, we develop the numerical algorithms necessary in substantial...
Population processes with unbounded extinction rate conditioned to non-extinction
Champagnat, Nicolas; Villemonais, Denis
2016-01-01
This article studies the quasi-stationary behaviour of population processes with unbounded absorption rate, including one-dimensional birth and death processes with catastrophes and multi-dimensional birth and death processes, modeling biological populations in interaction. To handle this situation, we develop original non-linear Lyapunov criteria. We obtain the exponential convergence in total variation of the conditional distributions to a unique quasi-stationary distribution, uniformly wit...
Intelligent modeling and control for nonlinear systems with rate-dependent hysteresis
Institute of Scientific and Technical Information of China (English)
MAO JianQin; DING HaiShan
2009-01-01
A new modeling approach for nonlinear systems with rate-dependent hysteresis is proposed. The ap-proach is used for the modeling of the giant magnetostrictive actuator, which has the rate-dependent nonlinear property. The models built are simpler than the existed approaches. Compared with the exper-intent result, the model built can well describe the hysteresis nonlinear of the actuator for Input signals with complex frequency. An adaptive direct inverse control approach is proposed based on the fuzzy tree model and Inverse learning and special learning that are used in neural network broadly. In this approach, the inverse model of the plant is identified to be the initial controller firstly. Then, the inverse model Is connected with the plant in series and the linear parameters of the controller are adjusted using the least mean square algorithm by on-line manner. The direct Inverse control approach based on the fuzzy tree model is applied on the tracing control of the actuator by simulation. The simulation results show the correctness of the approach.
In-TFT-Array-Process Micro Defect Inspection Using Nonlinear Principal Component Analysis
Directory of Open Access Journals (Sweden)
Zhi-Hao Kang
2009-10-01
Full Text Available Defect inspection plays a critical role in thin film transistor liquid crystal display (TFT-LCD manufacture, and has received much attention in the field of automatic optical inspection (AOI. Previously, most focus was put on the problems of macro-scale Mura-defect detection in cell process, but it has recently been found that the defects which substantially influence the yield rate of LCD panels are actually those in the TFT array process, which is the first process in TFT-LCD manufacturing. Defect inspection in TFT array process is therefore considered a difficult task. This paper presents a novel inspection scheme based on kernel principal component analysis (KPCA algorithm, which is a nonlinear version of the well-known PCA algorithm. The inspection scheme can not only detect the defects from the images captured from the surface of LCD panels, but also recognize the types of the detected defects automatically. Results, based on real images provided by a LCD manufacturer in Taiwan, indicate that the KPCA-based defect inspection scheme is able to achieve a defect detection rate of over 99% and a high defect classification rate of over 96% when the imbalanced support vector machine (ISVM with 2-norm soft margin is employed as the classifier. More importantly, the inspection time is less than 1 s per input image.
Examining the reaction of monetary policy to exchange rate changes: A nonlinear ARDL approach
Manogaran, Lavaneesvari; Sek, Siok Kun
2017-04-01
Previous studies showed the exchange rate changes can have significant impacts on macroeconomic performance. Over fluctuation of exchange rate may lead to economic instability. Hence, monetary policy rule tends to react to exchange rate changes. Especially, in emerging economies where the policy-maker tends to limit the exchange rate movement through interventions. In this study, we seek to investigate how the monetary policy rule reacts to exchange rate changes. The nonlinear autoregressive distributed lag (NARDL) model is applied to capture the asymmetric effect of exchange rate changes on monetary policy reaction function (interest rate). We focus the study in ASEAN5 countries (Indonesia, Malaysia, Philippines, Thailand and Singapore). The results indicated the existence of asymmetric effect of exchange rates changes on the monetary reaction function for all ASEAN5 countries in the long-run. Where, in majority of the cases the monetary policy is reacting to the appreciation and depreciation of exchange rate by raising the policy rate. This affirms the intervention of policymakers with the `fear of floating' behavior.
Neural Generalized Predictive Control of a non-linear Process
DEFF Research Database (Denmark)
Sørensen, Paul Haase; Nørgård, Peter Magnus; Ravn, Ole
1998-01-01
The use of neural network in non-linear control is made difficult by the fact the stability and robustness is not guaranteed and that the implementation in real time is non-trivial. In this paper we introduce a predictive controller based on a neural network model which has promising stability...... detail and discuss the implementation difficulties. The neural generalized predictive controller is tested on a pneumatic servo sys-tem....
THE NONLINEAR CUSP-CATASTROPHE MODEL OF THE SEDIMENT TRANSPORT RATE
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
In the catastrophe theory of nonlinear science,the intensity of water-flow and the coefficient of non-uniformsediment m are regarded as two bound variables, and the in-tensity of bed-load transport Φ as the state variable in the mo-tion of non-uniform sediment in cusp-catastrophe model.Based on the standard equation of the cusp-catastrophe theo-ry, the relation equation between the intensity of bed-loadtransport Φ and the intensity of water-flow has been derivedby used coordinate transform and topology transform. The e-quation of bed load transport rate was built on the cusp-catas-trophe theory of nonlinear science. The others are applied toverify this equation, that the results calculated by the cusp-ca-tastrophe equation agree well with the other equations. Thisindicates that the cusp-catastrophe equation is reasonable, and the results fully reflect the characteristics of threshold motionand transport of non-uniform sediment. The purpose of thispaper is to explore the incipient motion and transport laws ofnon-uniform sediment from the viewpoint of nonlinear science.
Directory of Open Access Journals (Sweden)
S. I. Samsudin
2014-01-01
Full Text Available The wastewater treatment plant (WWTP is highly known with the nonlinearity of the control parameters, thus it is difficult to be controlled. In this paper, the enhancement of nonlinear PI controller (ENon-PI to compensate the nonlinearity of the activated sludge WWTP is proposed. The ENon-PI controller is designed by cascading a sector-bounded nonlinear gain to linear PI controller. The rate variation of the nonlinear gain kn is automatically updated based on adaptive interaction algorithm. Initiative to simplify the ENon-PI control structure by adapting kn has been proved by significant improvement under various dynamic influents. More than 30% of integral square error and 14% of integral absolute error are reduced compared to benchmark PI for DO control and nitrate in nitrogen removal control. Better average effluent qualities, less number of effluent violations, and lower aeration energy consumption resulted.
Zhang, Bo
The past decade has witnessed astounding boom in telecommunication network traffic. With the emergence of multimedia over Internet, the high-capacity optical transport systems have started to shift focus from the core network towards the end users. This trend leads to diverse optical networks with transparency and reconfigurability requirement. As single channel data rate continues to increase and channel spacing continues to shrink for high capacity, high spectral efficiency, the workload on conventional electronic signal processing elements in the router nodes continues to build up. Performing signal processing functions in the optical domain can potentially alleviate the speed bottleneck if the unique optical properties are efficiently leveraged to assist electronic processing methodologies. Ultra-high bandwidth capability along with the promise for multi-channel and format-transparent operation make optical signal processing an attractive technology which is expected to have great impact on future optical networks. For optical signal processing applications in fiber-optic network and systems, a laudable goal would be to explore the unique nonlinear optical processes in novel photonic devices. This dissertation investigates novel optical signal processing techniques through simulations and experimental demonstrations, analyzes limitations of these nonlinear processing elements and proposes techniques to enhance the system performance or designs for functional photonic modules. Two key signal-processing building blocks for future optical networks, namely slow-light-based tunable optical delay lines and SOA-based high-speed wavelength converters, are presented in the first part of the dissertation. Phase preserving and spectrally efficient slow light are experimentally demonstrated using advanced modulation formats. Functional and novel photonic modules, such as multi-channel synchronizer and variable-bit-rate optical time division multiplexer are designed and
The Dynamics of an Eco-Epidemiological Model with Nonlinear Incidence Rate
Directory of Open Access Journals (Sweden)
Raid Kamel Naji
2012-01-01
Full Text Available This paper treats the dynamical behavior of eco-epidemiological model with nonlinear incidence rate. A Holling type II prey-predator model with SI-type of disease in prey has been proposed and analyzed. The existence, uniqueness, and boundedness of the solution of the system are studied. The local and global dynamical behaviors are investigated. The conditions, which guarantee the occurring of Hopf bifurcation of the system, are established. Finally, further investigations for the global dynamics of the proposed system are carried out with the help of numerical simulations.
QUALITATIVE ANALYSIS OF AN SEIS EPIDEMIC MODEL WITH NONLINEAR INCIDENCE RATE
Institute of Scientific and Technical Information of China (English)
WANG La-di; LI Jian-quan
2006-01-01
By means of limit theory and Fonda's theorem, an SEIS epidemic model with constant recruitment and the disease-related rate is considered. The incidence term is of the nonlinear form, and the basic reproduction number is found. If the basic reproduction number is less than one, there exists only the disease-free equilibrium, which is globally asymptotically stable, and the disease dies out eventually. If the basic reproduction number is greater than one, besides the unstable disease-free equilibrium, there exists also a unique endemic equilibrium, which is locally asymptotically stable, and the disease is uniformly persistent.
PREFACE: International Workshop on Multi-Rate processes and Hysterisis
Mortell, Michael P.; O'Malley, Robert E.; Pokrovskii, Alexei V.; Sobolev, Vladimir A.
2006-12-01
We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can be considered as limit cases of time relaxation processes, or admit an approximation by a differential equation which is singular with respect to a particular parameter. However, the amount of interaction between practitioners of theories of systems with time relaxation and systems with hysteresis (and between the `relaxation' and `hysteresis' research communities) is still low. In recent years Ireland has become a home for a series of prestigious International Workshops in Singular Perturbations and Hysteresis: International Workshop on Hysteresis and Multi-scale Asymptotics (University College Cork, Ireland, 17-21 March 2004). Proceedings are published in Journal of Physics: Conference Series 22. International Workshop on Relaxation Oscillations and Hysteresis (University College Cork, Ireland, 1-6 April 2002). The related collection of invited lectures, was published as a volume Singular Perturbations and Hysteresis, SIAM, Philadelphia, 2005. International Workshop on Geometrical Methods of Nonlinear Analysis and Semiconductor Laser Dynamics (University College Cork, Ireland, 5-5 April 2001). A collection of invited papers has been published as a special issue of Proceedings of the Russian Academy of Natural Sciences: Nonlinear dynamics of laser and reacting systems. Among the aims of these workshops were to bring together leading experts in time relaxation and hysteresis phenomena in applied problems; to discuss important problems in areas such as reacting systems, semiconductor lasers, shock phenomena in economic modelling, fluid mechanics, etc
Real-Time Implementation of Nonlinear Optical Processing Functions.
1986-09-30
demonstrating that the memory is nonlinear and selective. The recording medium could be replaced with real-time media such as photorefractive crystals. Thicker...recording media Fi4 4. Schematic of experiment that d,.non* trated ,,pera have the added advantage of higher angular selectiv- "" . e e r aity. thus... geometrica snapes in contact ’A,.n a c-:’:ser ’Figure 51a’ ., and a spher:cal 4:verg.ng reference -eam Upion :"um’latlon of t -" c-’gram by the object beam
Baranov, Denis G; Milichko, Valentin A; Kudryashov, Sergey I; Krasnok, Alexander E; Belov, Pavel A
2016-01-01
Optically generated electron-hole plasma in high-index dielectric nanostructures was demonstrated as a means of tuning of their optical properties. However, until now an ultrafast operation regime of such plasma driven nanostructures has not been attained. Here, we perform pump-probe experiments with resonant silicon nanoparticles and report on dense optical plasma generation near the magnetic dipole resonance with ultrafast (about 2.5 ps) relaxation rate. Basing on experimental results, we develop an analytical model describing transient response of a nanocrystalline silicon nanoparticle to an intense laser pulse and show theoretically that plasma induced optical nonlinearity leads to ultrafast reconfiguration of the scattering power pattern. We demonstrate 100 fs switching to unidirectional scattering regime upon irradiation of the nanoparticle by an intense femtosecond pulse. Our work lays the foundation for developing ultracompact and ultrafast all-optical signal processing devices.
Approaches to handle nonlinearities and nonnormalities in process chemometrics
Thissen, Uwe Maria Johannes
2004-01-01
For every industrial process, it is of paramount interest to online monitor the performance of the process and to assess the quality of the products made. In order to meet these goals, the field of process control works on understanding and improving industrial processes. Process chemometrics can be
A nonlinear optoelectronic filter for electronic signal processing
Loh, William; Yegnanarayanan, Siva; Ram, Rajeev J.; Juodawlkis, Paul W.
2014-01-01
The conversion of electrical signals into modulated optical waves and back into electrical signals provides the capacity for low-loss radio-frequency (RF) signal transfer over optical fiber. Here, we show that the unique properties of this microwave-photonic link also enable the manipulation of RF signals beyond what is possible in conventional systems. We achieve these capabilities by realizing a novel nonlinear filter, which acts to suppress a stronger RF signal in the presence of a weaker signal independent of their separation in frequency. Using this filter, we demonstrate a relative suppression of 56 dB for a stronger signal having a 1-GHz center frequency, uncovering the presence of otherwise undetectable weaker signals located as close as 3.5 Hz away. The capabilities of the optoelectronic filter break the conventional limits of signal detection, opening up new possibilities for radar and communication systems, and for the field of precision frequency metrology. PMID:24402418
Nonlinear model predictive control for chemical looping process
Energy Technology Data Exchange (ETDEWEB)
Joshi, Abhinaya; Lei, Hao; Lou, Xinsheng
2017-08-22
A control system for optimizing a chemical looping ("CL") plant includes a reduced order mathematical model ("ROM") that is designed by eliminating mathematical terms that have minimal effect on the outcome. A non-linear optimizer provides various inputs to the ROM and monitors the outputs to determine the optimum inputs that are then provided to the CL plant. An estimator estimates the values of various internal state variables of the CL plant. The system has one structure adapted to control a CL plant that only provides pressure measurements in the CL loops A and B, a second structure adapted to a CL plant that provides pressure measurements and solid levels in both loops A, and B, and a third structure adapted to control a CL plant that provides full information on internal state variables. A final structure provides a neural network NMPC controller to control operation of loops A and B.
Linear and Non-Linear Associations of Gonorrhea Diagnosis Rates with Social Determinants of Health
Directory of Open Access Journals (Sweden)
Hazel D. Dean
2012-09-01
Full Text Available Identifying how social determinants of health (SDH influence the burden of disease in communities and populations is critically important to determine how to target public health interventions and move toward health equity. A holistic approach to disease prevention involves understanding the combined effects of individual, social, health system, and environmental determinants on geographic area-based disease burden. Using 2006–2008 gonorrhea surveillance data from the National Notifiable Sexually Transmitted Disease Surveillance and SDH variables from the American Community Survey, we calculated the diagnosis rate for each geographic area and analyzed the associations between those rates and the SDH and demographic variables. The estimated product moment correlation (PMC between gonorrhea rate and SDH variables ranged from 0.11 to 0.83. Proportions of the population that were black, of minority race/ethnicity, and unmarried, were each strongly correlated with gonorrhea diagnosis rates. The population density, female proportion, and proportion below the poverty level were moderately correlated with gonorrhea diagnosis rate. To better understand relationships among SDH, demographic variables, and gonorrhea diagnosis rates, more geographic area-based estimates of additional variables are required. With the availability of more SDH variables and methods that distinguish linear from non-linear associations, geographic area-based analysis of disease incidence and SDH can add value to public health prevention and control programs.
Jesudason, Christopher G
2011-01-01
The primary emphasis of this work on kinetics is to illustrate the a posteriori approach to applications, where focus on data leads to novel outcomes, rather than the a priori tendencies of applied analysis which imposes constructs on the nature of the observable. The secondary intention is the development of appropriate methods consonant with experimental definitions. By focusing on gradients, it is possible to determine both the average and instantaneous rate constants that can monitor changes in the rate constant with concentration changes as suggested by this theory. Here, methods are developed and discussed utilizing nonlinear analysis which does not require exact knowledge of initial concentrations. These methods are compared with those derived from standard methodology. These gradient methods are shown to be consistent with the ones from standard methods and could readily serve as alternatives for studies where there are limits or unknowns in the initial conditions, such as in the burgeoning fields of ...
Semrau, Daniel; Xu, Tianhua; Shevchenko, Nikita A; Paskov, Milen; Alvarado, Alex; Killey, Robert I; Bayvel, Polina
2017-01-01
Achievable information rates (AIRs) of wideband optical communication systems using a ∼40 nm (∼5 THz) erbium-doped fiber amplifier and ∼100 nm (∼12.5 THz) distributed Raman amplification are estimated based on a first-order perturbation analysis. The AIRs of each individual channel have been evaluated for DP-64QAM, DP-256QAM, and DP-1024QAM modulation formats. The impact of full-field nonlinear compensation (FF-NLC) and probabilistically shaped constellations using a Maxwell-Boltzmann distribution were studied and compared to electronic dispersion compensation. It has been found that a probabilistically shaped DP-1024QAM constellation, combined with FF-NLC, yields achievable information rates of ∼75 Tbit/s for the EDFA scheme and ∼223 Tbit/s for the Raman amplification scheme over a 2000 km standard single-mode fiber transmission.
Nonlinear Least-Squares Time-Difference Estimation from Sub-Nyquist-Rate Samples
Harada, Koji; Sakai, Hideaki
In this paper, time-difference estimation of filtered random signals passed through multipath channels is discussed. First, we reformulate the approach based on innovation-rate sampling (IRS) to fit our random signal model, then use the IRS results to drive the nonlinear least-squares (NLS) minimization algorithm. This hybrid approach (referred to as the IRS-NLS method) provides consistent estimates even for cases with sub-Nyquist sampling assuming the use of compactly-supported sampling kernels that satisfies the recently-developed nonaliasing condition in the frequency domain. Numerical simulations show that the proposed NLS-IRS method can improve performance over the straight-forward IRS method, and provides approximately the same performance as the NLS method with reduced sampling rate, even for closely-spaced time delays. This enables, given a fixed observation time, significant reduction in the required number of samples, while maintaining the same level of estimation performance.
Institute of Scientific and Technical Information of China (English)
Yun Li; Hiroshi Kashiwagi
2005-01-01
Model Predictive Control (MPC) has recently found wide acceptance in the process industry, but existing design and implementation methods are restricted to linear process models. A chemical process, however, involves severe nonlinearity which cannot be ignored in practice. This paper aims to solve this nonlinear control problem by extending MPC to accommodate nonlinear models. It develops an analytical framework for nonlinear model predictive control (NMPC). It also offers a third-order Volterra series based nonparametric nonlinear modelling technique for NMPC design, which relieves practising engineers from the need for deriving a physical-principles based model first. An on-line realisation technique for implementing NMPC is then developed and applied to a Mitsubishi Chemicals polymerisation reaction process. Results show that this nonlinear MPC technique is feasible and very effective. It considerably outperforms linear and low-order Volterra model based methods. The advantages of the developed approach lie not only in control performance superior to existing NMPC methods, but also in eliminating the need for converting an analytical model and then convert it to a Volterra model obtainable only up to the second order.
State Anxiety and Nonlinear Dynamics of Heart Rate Variability in Students
Dimitriev, Aleksey D.
2016-01-01
Objectives Clinical and experimental research studies have demonstrated that the emotional experience of anxiety impairs heart rate variability (HRV) in humans. The present study investigated whether changes in state anxiety (SA) can also modulate nonlinear dynamics of heart rate. Methods A group of 96 students volunteered to participate in the study. For each student, two 5-minute recordings of beat intervals (RR) were performed: one during a rest period and one just before a university examination, which was assumed to be a real-life stressor. Nonlinear analysis of HRV was performed. The Spielberger’s State-Trait Anxiety Inventory was used to assess the level of SA. Results Before adjusting for heart rate, a Wilcoxon matched pairs test showed significant decreases in Poincaré plot measures, entropy, largest Lyapunov exponent (LLE), and pointwise correlation dimension (PD2), and an increase in the short-term fractal-like scaling exponent of detrended fluctuation analysis (α1) during the exam session, compared with the rest period. A Pearson analysis indicated significant negative correlations between the dynamics of SA and Poincaré plot axes ratio (SD1/SD2), and between changes in SA and changes in entropy measures. A strong negative correlation was found between the dynamics of SA and LLE. A significant positive correlation was found between the dynamics of SA and α1. The decreases in Poincaré plot measures (SD1, complex correlation measure), entropy measures, and LLE were still significant after adjusting for heart rate. Corrected α1 was increased during the exam session. As before, the dynamics of adjusted LLE was significantly correlated with the dynamics of SA. Conclusions The qualitative increase in SA during academic examination was related to the decrease in the complexity and size of the Poincaré plot through a reduction of both the interbeat interval and its variation. PMID:26807793
State Anxiety and Nonlinear Dynamics of Heart Rate Variability in Students.
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Dimitriy A Dimitriev
Full Text Available Clinical and experimental research studies have demonstrated that the emotional experience of anxiety impairs heart rate variability (HRV in humans. The present study investigated whether changes in state anxiety (SA can also modulate nonlinear dynamics of heart rate.A group of 96 students volunteered to participate in the study. For each student, two 5-minute recordings of beat intervals (RR were performed: one during a rest period and one just before a university examination, which was assumed to be a real-life stressor. Nonlinear analysis of HRV was performed. The Spielberger's State-Trait Anxiety Inventory was used to assess the level of SA.Before adjusting for heart rate, a Wilcoxon matched pairs test showed significant decreases in Poincaré plot measures, entropy, largest Lyapunov exponent (LLE, and pointwise correlation dimension (PD2, and an increase in the short-term fractal-like scaling exponent of detrended fluctuation analysis (α1 during the exam session, compared with the rest period. A Pearson analysis indicated significant negative correlations between the dynamics of SA and Poincaré plot axes ratio (SD1/SD2, and between changes in SA and changes in entropy measures. A strong negative correlation was found between the dynamics of SA and LLE. A significant positive correlation was found between the dynamics of SA and α1. The decreases in Poincaré plot measures (SD1, complex correlation measure, entropy measures, and LLE were still significant after adjusting for heart rate. Corrected α1 was increased during the exam session. As before, the dynamics of adjusted LLE was significantly correlated with the dynamics of SA.The qualitative increase in SA during academic examination was related to the decrease in the complexity and size of the Poincaré plot through a reduction of both the interbeat interval and its variation.
Blind Image Deblurring Driven by Nonlinear Processing in the Edge Domain
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Stefania Colonnese
2004-12-01
Full Text Available This work addresses the problem of blind image deblurring, that is, of recovering an original image observed through one or more unknown linear channels and corrupted by additive noise. We resort to an iterative algorithm, belonging to the class of Bussgang algorithms, based on alternating a linear and a nonlinear image estimation stage. In detail, we investigate the design of a novel nonlinear processing acting on the Radon transform of the image edges. This choice is motivated by the fact that the Radon transform of the image edges well describes the structural image features and the effect of blur, thus simplifying the nonlinearity design. The effect of the nonlinear processing is to thin the blurred image edges and to drive the overall blind restoration algorithm to a sharp, focused image. The performance of the algorithm is assessed by experimental results pertaining to restoration of blurred natural images.
Data Analysis Techniques for Resolving Nonlinear Processes in Plasmas : a Review
de Wit, T. Dudok
1996-01-01
The growing need for a better understanding of nonlinear processes in plasma physics has in the last decades stimulated the development of new and more advanced data analysis techniques. This review lists some of the basic properties one may wish to infer from a data set and then presents appropriate analysis techniques with some recent applications. The emphasis is put on the investigation of nonlinear wave phenomena and turbulence in space plasmas.
Linear and nonlinear analysis of normal and CAD-affected heart rate signals.
Acharya, U Rajendra; Faust, Oliver; Sree, Vinitha; Swapna, G; Martis, Roshan Joy; Kadri, Nahrizul Adib; Suri, Jasjit S
2014-01-01
Coronary artery disease (CAD) is one of the dangerous cardiac disease, often may lead to sudden cardiac death. It is difficult to diagnose CAD by manual inspection of electrocardiogram (ECG) signals. To automate this detection task, in this study, we extracted the heart rate (HR) from the ECG signals and used them as base signal for further analysis. We then analyzed the HR signals of both normal and CAD subjects using (i) time domain, (ii) frequency domain and (iii) nonlinear techniques. The following are the nonlinear methods that were used in this work: Poincare plots, Recurrence Quantification Analysis (RQA) parameters, Shannon entropy, Approximate Entropy (ApEn), Sample Entropy (SampEn), Higher Order Spectra (HOS) methods, Detrended Fluctuation Analysis (DFA), Empirical Mode Decomposition (EMD), Cumulants, and Correlation Dimension. As a result of the analysis, we present unique recurrence, Poincare and HOS plots for normal and CAD subjects. We have also observed significant variations in the range of these features with respect to normal and CAD classes, and have presented the same in this paper. We found that the RQA parameters were higher for CAD subjects indicating more rhythm. Since the activity of CAD subjects is less, similar signal patterns repeat more frequently compared to the normal subjects. The entropy based parameters, ApEn and SampEn, are lower for CAD subjects indicating lower entropy (less activity due to impairment) for CAD. Almost all HOS parameters showed higher values for the CAD group, indicating the presence of higher frequency content in the CAD signals. Thus, our study provides a deep insight into how such nonlinear features could be exploited to effectively and reliably detect the presence of CAD. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
Modelling nonlinear behavior of labor force participation rate by STAR: An application for Turkey
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Sibel Cengiz
2014-04-01
Full Text Available The aim of this paper is to contribute to the understanding of the behavior of participation rates in terms of gender differences. We employed smooth autoregressive transition models for the quarterly Turkish labor force participation rates (LFPR data between 2000: Q1 - 2011: Q4 to present an asymmetric participation behavior. The smoothness parameter indicates a gradual transition from low to high regimes. It is higher for female workers compared to the male workers. Participation rates diminish during a recession but they increase smoothly during the periods of expansion. The estimation results of Enders et al. (1998 also verified the asymmetry and nonlinearity in participation rates. During periods of economic expansion, they are higher than the threshold but the low regime indicator function takes the value zero. The results of the paper have economic implications for policy makers. Due to the discouraged worker and added worker effects, LFPR should be observed with the unemployment rates while evaluating the tightness of the labor market.
Simulations of the Ocean Response to a Hurricane: Nonlinear Processes
Zedler, Sarah E.
2009-10-01
Superinertial internal waves generated by a tropical cyclone can propagate vertically and laterally away from their local generation site and break, contributing to turbulent vertical mixing in the deep ocean and maintenance of the stratification of the main thermocline. In this paper, the results of a modeling study are reported to investigate the mechanism by which superinertial fluctuations are generated in the deep ocean. The general properties of the superinertial wave wake were also characterized as a function of storm speed and central latitude. The Massachusetts Institute of Technology (MIT) Ocean General Circulation Model (OGCM) was used to simulate the open ocean response to realistic westward-tracking hurricane-type surface wind stress and heat and net freshwater buoyancy forcing for regions representative of midlatitudes in the Atlantic, the Caribbean, and low latitudes in the eastern Pacific. The model had high horizontal [Δ(x, y) = 1/6°] and vertical (Δz = 5 m in top 100 m) resolution and employed a parameterization for vertical mixing induced by shear instability. In the horizontal momentum equation, the relative size of the nonlinear advection terms, which had a dominant frequency near twice the inertial, was large only in the upper 200 m of water. Below 200 m, the linear momentum equations obeyed a linear balance to 2%. Fluctuations at nearly twice the inertial frequency (2f) were prevalent throughout the depth of the water column, indicating that these nonlinear advection terms in the upper 200 m forced a linear mode below at nearly twice the inertial frequency via vorticity conservation. Maximum variance at 2f in horizontal velocity occurred on the south side of the track. This was in response to vertical advection of northward momentum, which in the north momentum equation is an oscillatory positive definite term that constituted a net force to the south at a frequency near 2f. The ratio of this term to the Coriolis force was larger on the
Nonlinearities in the quantum measurement process of superconducting qubits
Energy Technology Data Exchange (ETDEWEB)
Serban, Ioana
2008-05-15
The work described in this thesis focuses on the investigation of decoherence and measurement backaction, on the theoretical description of measurement schemes and their improvement. The study presented here is centered around quantum computing implementations using superconducting devices and most important, the Josephson effect. The measured system is invariantly a qubit, i. e. a two-level system. The objective is to study detectors with increasing nonlinearity, e. g. coupling of the qubit to the frequency a driven oscillator, or to the bifurcation amplifier, to determine the performance and backaction of the detector on the measured system and to investigate the importance of a strong qubit-detector coupling for the achievement of a quantum non-demolition type of detection. The first part gives a very basic introduction to quantum information, briefly reviews some of the most promising physical implementations of a quantum computer before focusing on the superconducting devices. The second part presents a series of studies of different qubit measurements, describing the backaction of the measurement onto the measured system and the internal dynamics of the detector. Methodology adapted from quantum optics and chemical physics (master equations, phase-space analysis etc.) combined with the representation of a complex environment yielded a tool capable of describing a nonlinear, non-Markovian environment, which couples arbitrarily strongly to the measured system. This is described in chapter 3. Chapter 4 focuses on the backaction on the qubit and presents novel insights into the qubit dephasing in the strong coupling regime. Chapter 5 uses basically the same system and technical tools to explore the potential of a fast, strong, indirect measurement, and determine how close such a detection would ideally come to the quantum non-demolition regime. Chapter 6 focuses on the internal dynamics of a strongly driven Josephson junction. The analytical results are based on
Kannan, Rohit; Tangirala, Arun K.
2014-06-01
Identification of directional influences in multivariate systems is of prime importance in several applications of engineering and sciences such as plant topology reconstruction, fault detection and diagnosis, and neurosciences. A spectrum of related directionality measures, ranging from linear measures such as partial directed coherence (PDC) to nonlinear measures such as transfer entropy, have emerged over the past two decades. The PDC-based technique is simple and effective, but being a linear directionality measure has limited applicability. On the other hand, transfer entropy, despite being a robust nonlinear measure, is computationally intensive and practically implementable only for bivariate processes. The objective of this work is to develop a nonlinear directionality measure, termed as KPDC, that possesses the simplicity of PDC but is still applicable to nonlinear processes. The technique is founded on a nonlinear measure called correntropy, a recently proposed generalized correlation measure. The proposed method is equivalent to constructing PDC in a kernel space where the PDC is estimated using a vector autoregressive model built on correntropy. A consistent estimator of the KPDC is developed and important theoretical results are established. A permutation scheme combined with the sequential Bonferroni procedure is proposed for testing hypothesis on absence of causality. It is demonstrated through several case studies that the proposed methodology effectively detects Granger causality in nonlinear processes.
Institute of Scientific and Technical Information of China (English)
TAO Hua-xue (陶华学); GUO Jin-yun (郭金运)
2003-01-01
Data are very important to build the digital mine. Data come from many sources, have different types and temporal states. Relations between one class of data and the other one, or between data and unknown parameters are more nonlinear. The unknown parameters are non-random or random, among which the random parameters often dynamically vary with time. Therefore it is not accurate and reliable to process the data in building the digital mine with the classical least squares method or the method of the common nonlinear least squares. So a generalized nonlinear dynamic least squares method to process data in building the digital mine is put forward. In the meantime, the corresponding mathematical model is also given. The generalized nonlinear least squares problem is more complex than the common nonlinear least squares problem and its solution is more difficultly obtained because the dimensions of data and parameters in the former are bigger. So a new solution model and the method are put forward to solve the generalized nonlinear dynamic least squares problem. In fact, the problem can be converted to two sub-problems, each of which has a single variable. That is to say, a complex problem can be separated and then solved. So the dimension of unknown parameters can be reduced to its half, which simplifies the original high dimensional equations. The method lessens the calculating load and opens up a new way to process the data in building the digital mine, which have more sources, different types and more temporal states.
Motulsky, Harvey J; Brown, Ronald E
2006-03-09
Nonlinear regression, like linear regression, assumes that the scatter of data around the ideal curve follows a Gaussian or normal distribution. This assumption leads to the familiar goal of regression: to minimize the sum of the squares of the vertical or Y-value distances between the points and the curve. Outliers can dominate the sum-of-the-squares calculation, and lead to misleading results. However, we know of no practical method for routinely identifying outliers when fitting curves with nonlinear regression. We describe a new method for identifying outliers when fitting data with nonlinear regression. We first fit the data using a robust form of nonlinear regression, based on the assumption that scatter follows a Lorentzian distribution. We devised a new adaptive method that gradually becomes more robust as the method proceeds. To define outliers, we adapted the false discovery rate approach to handling multiple comparisons. We then remove the outliers, and analyze the data using ordinary least-squares regression. Because the method combines robust regression and outlier removal, we call it the ROUT method. When analyzing simulated data, where all scatter is Gaussian, our method detects (falsely) one or more outlier in only about 1-3% of experiments. When analyzing data contaminated with one or several outliers, the ROUT method performs well at outlier identification, with an average False Discovery Rate less than 1%. Our method, which combines a new method of robust nonlinear regression with a new method of outlier identification, identifies outliers from nonlinear curve fits with reasonable power and few false positives.
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Motulsky Harvey J
2006-03-01
Full Text Available Abstract Background Nonlinear regression, like linear regression, assumes that the scatter of data around the ideal curve follows a Gaussian or normal distribution. This assumption leads to the familiar goal of regression: to minimize the sum of the squares of the vertical or Y-value distances between the points and the curve. Outliers can dominate the sum-of-the-squares calculation, and lead to misleading results. However, we know of no practical method for routinely identifying outliers when fitting curves with nonlinear regression. Results We describe a new method for identifying outliers when fitting data with nonlinear regression. We first fit the data using a robust form of nonlinear regression, based on the assumption that scatter follows a Lorentzian distribution. We devised a new adaptive method that gradually becomes more robust as the method proceeds. To define outliers, we adapted the false discovery rate approach to handling multiple comparisons. We then remove the outliers, and analyze the data using ordinary least-squares regression. Because the method combines robust regression and outlier removal, we call it the ROUT method. When analyzing simulated data, where all scatter is Gaussian, our method detects (falsely one or more outlier in only about 1–3% of experiments. When analyzing data contaminated with one or several outliers, the ROUT method performs well at outlier identification, with an average False Discovery Rate less than 1%. Conclusion Our method, which combines a new method of robust nonlinear regression with a new method of outlier identification, identifies outliers from nonlinear curve fits with reasonable power and few false positives.
Ruth, D. C. S.; Costa Rodriguez, F.
2015-12-01
The most active volcanoes on earth erupt in a yearly to decadal time scales, typically erupt mafic magmas and are open-vent systems with prominent degassing plumes (e.g. Mayon, Arenal, Llaima, Etna). Here we investigate the plumbing systems, dynamics, and processes that drive eruptions at these systems. These are key questions for improving hazard evaluation, and better understanding the unrest associated with these types of volcanoes. The petrology and geochemistry from six historical eruptions (1947-2006) of Mayon volcano (Philippines) shows that all lavas are basaltic andesite with phenocrysts of plagioclase + orthopyroxene (Opx) + clinopyroxene. Opx crystals show a variety of compositions and zoning patterns (reverse, normal or complex) with Mg# (= 100 *Mg/[Mg+Fe]) varying from 67 to 81. The simplest interpretation is that the low Mg# parts of the crystals resided on an upper crustal and crystal rich reservoir that was intruded by more primitive magmas from which the high Mg# parts of the crystals grew. Modelling Mg-Fe diffusion in Opx shows that times since magma injection and eruption range from a few days up to 3.5 years in all of the investigated eruptions. The longest diffusion times are shorter than the repose times between the eruptions, which implies that crystal recycling between eruptive events is negligible. This is a surprising result that shows that for each eruption a different part of the evolved crystal-rich plumbing system is activated. This can be due to random intrusion location or an irreversibility of the plumbing system that prevents multiple eruptions from the same crystal-rich part. Moreover, we find that the number of intrusions markedly increases before each eruption in a non-linear manner. Such an increased rate of intrusions with time might reflect non-linear rheological properties of the crystal-rich system, of the enclosing rocks, or the non-linear evolution of crystal-melt reaction-dissolution fronts during magma intrusions.
Nonlinear Methods to Assess Changes in Heart Rate Variability in Type 2 Diabetic Patients
Energy Technology Data Exchange (ETDEWEB)
Bhaskar, Roy, E-mail: imbhaskarall@gmail.com [Indian Institute of Technology (India); University of Connecticut, Farmington, CT (United States); Ghatak, Sobhendu [Indian Institute of Technology (India)
2013-10-15
Heart rate variability (HRV) is an important indicator of autonomic modulation of cardiovascular function. Diabetes can alter cardiac autonomic modulation by damaging afferent inputs, thereby increasing the risk of cardiovascular disease. We applied nonlinear analytical methods to identify parameters associated with HRV that are indicative of changes in autonomic modulation of heart function in diabetic patients. We analyzed differences in HRV patterns between diabetic and age-matched healthy control subjects using nonlinear methods. Lagged Poincaré plot, autocorrelation, and detrended fluctuation analysis were applied to analyze HRV in electrocardiography (ECG) recordings. Lagged Poincare plot analysis revealed significant changes in some parameters, suggestive of decreased parasympathetic modulation. The detrended fluctuation exponent derived from long-term fitting was higher than the short-term one in the diabetic population, which was also consistent with decreased parasympathetic input. The autocorrelation function of the deviation of inter-beat intervals exhibited a highly correlated pattern in the diabetic group compared with the control group. The HRV pattern significantly differs between diabetic patients and healthy subjects. All three statistical methods employed in the study may prove useful to detect the onset and extent of autonomic neuropathy in diabetic patients.
Energy Technology Data Exchange (ETDEWEB)
He, Zhaoguo [Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zong, Qiugang, E-mail: qgzong@gmail.com; Wang, Yongfu [Institute of Space Physics and Applied Technology, Peking University, Beijing 100871 (China); Liu, Siqing; Lin, Ruilin; Shi, Liqin [Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China)
2014-12-15
Resonant pitch angle scattering by electromagnetic ion cyclotron (EMIC) waves has been suggested to account for the rapid loss of ring current ions and radiation belt electrons. For the rising tone EMIC wave (classified as triggered EMIC emission), its frequency sweep rate strongly affects the efficiency of pitch-angle scattering. Based on the Cluster observations, we analyze three typical cases of rising tone EMIC waves. Two cases locate at the nightside (22.3 and 22.6 magnetic local time (MLT)) equatorial region and one case locates at the duskside (18MLT) higher magnetic latitude (λ = –9.3°) region. For the three cases, the time-dependent wave amplitude, cold electron density, and cold ion density ratio are derived from satellite data; while the ambient magnetic field, thermal proton perpendicular temperature, and the wave spectral can be directly provided by observation. These parameters are input into the nonlinear wave growth model to simulate the time-frequency evolutions of the rising tones. The simulated results show good agreements with the observations of the rising tones, providing further support for the previous finding that the rising tone EMIC wave is excited through the nonlinear wave growth process.
He, Zhaoguo; Zong, Qiugang; Liu, Siqing; Wang, Yongfu; Lin, Ruilin; Shi, Liqin
2014-12-01
Resonant pitch angle scattering by electromagnetic ion cyclotron (EMIC) waves has been suggested to account for the rapid loss of ring current ions and radiation belt electrons. For the rising tone EMIC wave (classified as triggered EMIC emission), its frequency sweep rate strongly affects the efficiency of pitch-angle scattering. Based on the Cluster observations, we analyze three typical cases of rising tone EMIC waves. Two cases locate at the nightside (22.3 and 22.6 magnetic local time (MLT)) equatorial region and one case locates at the duskside (18MLT) higher magnetic latitude (λ = -9.3°) region. For the three cases, the time-dependent wave amplitude, cold electron density, and cold ion density ratio are derived from satellite data; while the ambient magnetic field, thermal proton perpendicular temperature, and the wave spectral can be directly provided by observation. These parameters are input into the nonlinear wave growth model to simulate the time-frequency evolutions of the rising tones. The simulated results show good agreements with the observations of the rising tones, providing further support for the previous finding that the rising tone EMIC wave is excited through the nonlinear wave growth process.
Lainscsek, C.; Rowat, P.; Schettino, L.; Lee, D.; Song, D.; Letellier, C.; Poizner, H.
2012-03-01
Parkinson's disease is a degenerative condition whose severity is assessed by clinical observations of motor behaviors. These are performed by a neurological specialist through subjective ratings of a variety of movements including 10-s bouts of repetitive finger-tapping movements. We present here an algorithmic rating of these movements which may be beneficial for uniformly assessing the progression of the disease. Finger-tapping movements were digitally recorded from Parkinson's patients and controls, obtaining one time series for every 10 s bout. A nonlinear delay differential equation, whose structure was selected using a genetic algorithm, was fitted to each time series and its coefficients were used as a six-dimensional numerical descriptor. The algorithm was applied to time-series from two different groups of Parkinson's patients and controls. The algorithmic scores compared favorably with the unified Parkinson's disease rating scale scores, at least when the latter adequately matched with ratings from the Hoehn and Yahr scale. Moreover, when the two sets of mean scores for all patients are compared, there is a strong (r = 0.785) and significant (p <0.0015) correlation between them.
PREFACE: International Workshop on Multi-Rate Processes and Hysteresis
Mortell, Michael P.; O'Malley, Robert E.; Pokrovskii, Alexei; Rachinskii, Dmitrii; Sobolev, Vladimir A.
2008-07-01
We are interested in singular perturbation problems and hysteresis as common strongly nonlinear phenomena that occur in many industrial, physical and economic systems. The wording `strongly nonlinear' means that linearization will not encapsulate the observed phenomena. Often these two types of phenomena are manifested for different stages of the same or similar processes. A number of fundamental hysteresis models can be considered as limit cases of time relaxation processes, or admit an approximation by a differential equation which is singular with respect to a particular parameter. However, the amount of interaction between practitioners of theories of systems with time relaxation and systems with hysteresis (and between the `relaxation' and `hysteresis' research communities) is still low, and cross-fertilization is small. In recent years Ireland has become a home for a series of prestigious International Workshops in Singular Perturbations and Hysteresis: International Workshop on Multi-rate Processes and Hysteresis (University College Cork, Ireland, 3-8 April 2006). Proceedings are published in Journal of Physics: Conference Series, volume 55. See further information at http://euclid.ucc.ie/murphys2008.htm International Workshop on Hysteresis and Multi-scale Asymptotics (University College Cork, Ireland, 17-21 March 2004). Proceedings are published in Journal of Physics: Conference Series, volume 22. See further information at http://euclid.ucc.ie/murphys2006.htm International Workshop on Relaxation Oscillations and Hysteresis (University College Cork, Ireland, 1-6 April 2002). The related collection of invited lectures, was published as a volume Singular Perturbations and Hysteresis, SIAM, Philadelphia, 2005. See further information at http://euclid.ucc.ie/hamsa2004.htm International Workshop on Geometrical Methods of Nonlinear Analysis and Semiconductor Laser Dynamics (University College Cork, Ireland, 5-5 April 2001). A collection of invited papers has been
Shinkawa, Mizuki; Ishikura, Norihiro; Hama, Yosuke; Suzuki, Keijiro; Baba, Toshihiko
2011-10-24
We have studied low-dispersion slow light and its nonlinear enhancement in photonic crystal waveguides. In this work, we fabricated the waveguides using Si CMOS-compatible process. It enables us to integrate spotsize converters, which greatly simplifies the optical coupling from fibers as well as demonstration of the nonlinear enhancement. Two-photon absorption, self-phase modulation and four-wave mixing were observed clearly for picosecond pulses in a 200-μm-long device. In comparison with Si wire waveguides, a 60-120 fold higher nonlinearity was evaluated for a group index of 51. Unique intensity response also occurred due to the specific transmission spectrum and enhanced nonlinearities. Such slow light may add various functionalities in Si photonics, while loss reduction is desired for ensuring the advantage of slow light.
Nonlinear Transport Processes in Tokamak Plasmas. Part I: The Collisional Regimes
Sonnino, Giorgio
2008-01-01
An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear (Onsager) transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch-Schlueter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for JET plasmas are also reported. We found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor, which may be of the order 100. The nonlinear classical coefficients exceed the neoclassical ones by a factor, which may be of order 2. The expressions of the ion transport coefficients, determined by the neoclassical theory in these two regimes, remain...
Institute of Scientific and Technical Information of China (English)
Xiao Li; Zhang Wei; Huang Yi-Dong; Peng Jiang-De
2008-01-01
High nonlinear microstructure fibre (HNMF) is preferred in nonlinear fibre optics, especially in the applications of optical parametric effects, due to its high optical nonlinear coefficient. However, polarization dependent dispersion will impact the nonlinear optical parametric process in HNMFs. In this paper, modulation instability (MI) method is used to measure the polarization dependent dispersion of a piece of commercial HNMF, including the group velocity dispersion, the dispersion slope, the fourth-order dispersion and group birefringence. It also experimentally demonstrates the impact of the polarization dependent dispersion on the continuous wave supercontinuum (SC) generation. On one axis MI sidebands with symmetric frequency dctunings are generated, while on the other axis with larger MI frequency detuning, SC is generated by soliton self-frequency shift.
Computational Modelling and Optimal Control of Ebola Virus Disease with non-Linear Incidence Rate
Takaidza, I.; Makinde, O. D.; Okosun, O. K.
2017-03-01
The 2014 Ebola outbreak in West Africa has exposed the need to connect modellers and those with relevant data as pivotal to better understanding of how the disease spreads and quantifying the effects of possible interventions. In this paper, we model and analyse the Ebola virus disease with non-linear incidence rate. The epidemic model created is used to describe how the Ebola virus could potentially evolve in a population. We perform an uncertainty analysis of the basic reproductive number R 0 to quantify its sensitivity to other disease-related parameters. We also analyse the sensitivity of the final epidemic size to the time control interventions (education, vaccination, quarantine and safe handling) and provide the cost effective combination of the interventions.
Global stability for delay SIR and SEIR epidemic models with nonlinear incidence rate.
Huang, Gang; Takeuchi, Yasuhiro; Ma, Wanbiao; Wei, Daijun
2010-07-01
In this paper, based on SIR and SEIR epidemic models with a general nonlinear incidence rate, we incorporate time delays into the ordinary differential equation models. In particular, we consider two delay differential equation models in which delays are caused (i) by the latency of the infection in a vector, and (ii) by the latent period in an infected host. By constructing suitable Lyapunov functionals and using the Lyapunov-LaSalle invariance principle, we prove the global stability of the endemic equilibrium and the disease-free equilibrium for time delays of any length in each model. Our results show that the global properties of equilibria also only depend on the basic reproductive number and that the latent period in a vector does not affect the stability, but the latent period in an infected host plays a positive role to control disease development.
Evaluating non-linear models on point and interval forecasts: an application with exchange rates
Directory of Open Access Journals (Sweden)
Emanuela Marrocu
2005-01-01
Full Text Available The aim of this paper is to compare the forecasting performance of SETAR and GARCH models against a linear benchmark using historical data for the returns of the Japanese yen/US dollar exchange rate. The relative performance of the models is evaluated on point forecasts and on interval forecasts. Point forecasts evaluation over the whole forecast period indicates that the performance of the models, when distinguishable, tends to favour the linear models. However, we show that if the evaluation of point forecasts is conducted over distinct subsamples or specific regimes there is more evidence of forecasting gains, especially from the SETAR models. Moreover, when we evaluate the validity of interval forecasts, the results produce clear evidence of the superiority of the non-linear models, and tend to favour especially the GARCH models.
Leydesdorff, L.; Rotolo, D.; de Nooy, W.
2013-01-01
The process of innovation follows nonlinear patterns across the domains of science, technology, and the economy. Novel bibliometric mapping techniques can be used to investigate and represent distinctive, but complementary perspectives on the innovation process (e.g. ‘demand’ and ‘supply’) as well
Directory of Open Access Journals (Sweden)
Pisit Leeahtam
2011-10-01
Full Text Available The objectives of this study are to find the fitting model and dependence measures of both Thailand’s exchange rate and Malaysia’s exchange rate during, between, and after the World’s recent financial crises based on linear, nonlinear and empirical copula approaches.The results of the study confirm that the nonlinear model (NNTs is an appropriate model for Thailand’s exchange rate return in percentage during the periods of 2008-2011but not for Malaysia’s exchange rate return. Based on empirical copula approach, the dependence measures are very small between Thailand’s exchange and Malaysia’s exchange. This seems to suggest that when global economy is affected by World’s financial crisis, the nonlinear approach should be used to predict Thailand’s exchange rate return in percentage. In addition, it suggests that both the nonlinear and linear approaches should be used to predict the Malaysia’s exchange rate return in percentage. Moreover, the relationship between the exchange rate of Thailand and that of Malaysia is not strong.This is also true for the currencies of both countries.
Barbieri, Riccardo; Matten, Eric C; Alabi, Abdulrasheed A; Brown, Emery N
2005-01-01
Heart rate is a vital sign, whereas heart rate variability is an important quantitative measure of cardiovascular regulation by the autonomic nervous system. Although the design of algorithms to compute heart rate and assess heart rate variability is an active area of research, none of the approaches considers the natural point-process structure of human heartbeats, and none gives instantaneous estimates of heart rate variability. We model the stochastic structure of heartbeat intervals as a history-dependent inverse Gaussian process and derive from it an explicit probability density that gives new definitions of heart rate and heart rate variability: instantaneous R-R interval and heart rate standard deviations. We estimate the time-varying parameters of the inverse Gaussian model by local maximum likelihood and assess model goodness-of-fit by Kolmogorov-Smirnov tests based on the time-rescaling theorem. We illustrate our new definitions in an analysis of human heartbeat intervals from 10 healthy subjects undergoing a tilt-table experiment. Although several studies have identified deterministic, nonlinear dynamical features in human heartbeat intervals, our analysis shows that a highly accurate description of these series at rest and in extreme physiological conditions may be given by an elementary, physiologically based, stochastic model.
Quasilinear Extreme Learning Machine Model Based Internal Model Control for Nonlinear Process
Directory of Open Access Journals (Sweden)
Dazi Li
2015-01-01
Full Text Available A new strategy for internal model control (IMC is proposed using a regression algorithm of quasilinear model with extreme learning machine (QL-ELM. Aimed at the chemical process with nonlinearity, the learning process of the internal model and inverse model is derived. The proposed QL-ELM is constructed as a linear ARX model with a complicated nonlinear coefficient. It shows some good approximation ability and fast convergence. The complicated coefficients are separated into two parts. The linear part is determined by recursive least square (RLS, while the nonlinear part is identified through extreme learning machine. The parameters of linear part and the output weights of ELM are estimated iteratively. The proposed internal model control is applied to CSTR process. The effectiveness and accuracy of the proposed method are extensively verified through numerical results.
A fuzzy model based adaptive PID controller design for nonlinear and uncertain processes.
Savran, Aydogan; Kahraman, Gokalp
2014-03-01
We develop a novel adaptive tuning method for classical proportional-integral-derivative (PID) controller to control nonlinear processes to adjust PID gains, a problem which is very difficult to overcome in the classical PID controllers. By incorporating classical PID control, which is well-known in industry, to the control of nonlinear processes, we introduce a method which can readily be used by the industry. In this method, controller design does not require a first principal model of the process which is usually very difficult to obtain. Instead, it depends on a fuzzy process model which is constructed from the measured input-output data of the process. A soft limiter is used to impose industrial limits on the control input. The performance of the system is successfully tested on the bioreactor, a highly nonlinear process involving instabilities. Several tests showed the method's success in tracking, robustness to noise, and adaptation properties. We as well compared our system's performance to those of a plant with altered parameters with measurement noise, and obtained less ringing and better tracking. To conclude, we present a novel adaptive control method that is built upon the well-known PID architecture that successfully controls highly nonlinear industrial processes, even under conditions such as strong parameter variations, noise, and instabilities.
Non-linear thermodynamic laws application to soil processes
Directory of Open Access Journals (Sweden)
Ilgiz Khabirov
2013-01-01
Full Text Available An attempt has been made to analyze the possibility to use nonequilibrium thermodynamics for the soil dynamic open systemstreatment. Entropy change of such a system and the entropy coming from or going into the outer sphere. In the steady state, dynamic soil-formation processes occur within an organized structure and are characterized by stable parameters close to equilibrium. Accordingly, when examining soil, one can proceed from the conventional thermodynamic equilibrium. However, the matter of Onzager-Prigozhin general phenomenological theory applicability to soil processes is more complicated. To study soil stability it is necessary to go beyond the limits of linear thermodynamics.
Nonlinear processes upon two-photon interband picosecond excitation of PbWO4 crystal
Lukanin, V. I.; Karasik, A. Ya
2016-09-01
A new experimental method is proposed to study the dynamics of nonlinear processes occurring upon two-photon interband picosecond excitation of a lead tungstate crystal and upon its excitation by cw probe radiation in a temporal range from several nanoseconds to several seconds. The method is applied to the case of crystal excitation by a sequence of 25 high-power picosecond pulses with a wavelength of 523.5 nm and 633-nm cw probe radiation. Measuring the probe beam transmittance during crystal excitation, one can investigate the influence of two-photon interband absorption and the thermal nonlinearity of the refractive index on the dynamics of nonlinear processes in a wide range of times (from several nanoseconds to several seconds). The time resolution of the measuring system makes it possible to distinguish fast and slow nonlinear processes of electronic or thermal nature, including the generation of a thermal lens and thermal diffusion. An alternative method is proposed to study the dynamics of induced absorption transformation and, therefore, the dynamics of the development of nonlinear rocesses upon degenerate two-photon excitation of the crystal in the absence of external probe radiation.
Linear and nonlinear optical processing of polymer matrix nanocomposites
DeJournett, Travis J.; Han, Karen; Olasov, Lauren R.; Zeng, Fan W.; Lee, Brennan; Spicer, James B.
2015-08-01
This work focuses on the scalable synthesis and processing of nanostructures in polymer matrix nanocomposites (PMNCs) for applications that require photochemical functionality of these nanostructures. An in situ vapor deposition process using various metal and metal oxide precursors has been used to create a range of nanocomposites that display photochromic and photocatalytic behaviors. Under specific processing conditions, these composites consist of discrete nanoparticles distributed uniformly throughout the bulk of an optically transparent polymer matrix. Incorporating other chemical species as supplementary deposition agents in the synthesis process can modify these particles and produce complicated nanostructures with enhanced properties. In particular, work has been carried out to structure nanoparticles using laser irradiation. Starting with metallic or metal oxide nanoparticles in the polymer matrix, localized chemical vapor deposition in the near-particle environment has been carried out using laser irradiation to decompose chemical precursors leading to the formation of secondary structures surrounding the seed nanoparticles. Control of the spatial and temporal characteristics of the excitation source allows for synthesis of nanocomposites with a high degree of control over the location, composition and size of nanoparticles in the matrix and presents the opportunity to produce patterned materials with spatially varying properties.
Faes, Luca; Zhao, He; Chon, Ki H; Nollo, Giandomenico
2009-03-01
We propose a method to extend to time-varying (TV) systems the procedure for generating typical surrogate time series, in order to test the presence of nonlinear dynamics in potentially nonstationary signals. The method is based on fitting a TV autoregressive (AR) model to the original series and then regressing the model coefficients with random replacements of the model residuals to generate TV AR surrogate series. The proposed surrogate series were used in combination with a TV sample entropy (SE) discriminating statistic to assess nonlinearity in both simulated and experimental time series, in comparison with traditional time-invariant (TIV) surrogates combined with the TIV SE discriminating statistic. Analysis of simulated time series showed that using TIV surrogates, linear nonstationary time series may be erroneously regarded as nonlinear and weak TV nonlinearities may remain unrevealed, while the use of TV AR surrogates markedly increases the probability of a correct interpretation. Application to short (500 beats) heart rate variability (HRV) time series recorded at rest (R), after head-up tilt (T), and during paced breathing (PB) showed: 1) modifications of the SE statistic that were well interpretable with the known cardiovascular physiology; 2) significant contribution of nonlinear dynamics to HRV in all conditions, with significant increase during PB at 0.2 Hz respiration rate; and 3) a disagreement between TV AR surrogates and TIV surrogates in about a quarter of the series, suggesting that nonstationarity may affect HRV recordings and bias the outcome of the traditional surrogate-based nonlinearity test.
Directory of Open Access Journals (Sweden)
Ömer Öztürkoğlu
2017-07-01
Full Text Available This study focuses on identical parallel machine scheduling of jobs with deteriorating processing times and rate-modifying activities. We consider non linearly increasing processing times of jobs based on their position assignment. Rate modifying activities are also considered to recover the increase in processing times of jobs due to deterioration. We also propose heuristics algorithms that rely on ant colony optimization and simulated annealing algorithms to solve the problem with multiple RMAs in a reasonable amount of time. Finally, we show that ant colony optimization algorithm generates close optimal solutions and superior results than simulated annealing algorithm.
A Kernel Time Structure Independent Component Analysis Method for Nonlinear Process Monitoring☆
Institute of Scientific and Technical Information of China (English)
Lianfang Cai; Xuemin Tian; Ni Zhang
2014-01-01
Kernel independent component analysis (KICA) is a newly emerging nonlinear process monitoring method, which can extract mutually independent latent variables cal ed independent components (ICs) from process var-iables. However, when more than one IC have Gaussian distribution, it cannot extract the IC feature effectively and thus its monitoring performance will be degraded drastical y. To solve such a problem, a kernel time struc-ture independent component analysis (KTSICA) method is proposed for monitoring nonlinear process in this paper. The original process data are mapped into a feature space nonlinearly and then the whitened data are calculated in the feature space by the kernel trick. Subsequently, a time structure independent component analysis algorithm, which has no requirement for the distribution of ICs, is proposed to extract the IC feature. Finally, two monitoring statistics are built to detect process faults. When some fault is detected, a nonlinear fault identification method is developed to identify fault variables based on sensitivity analysis. The proposed monitoring method is applied in the Tennessee Eastman benchmark process. Applications demonstrate the superiority of KTSICA over KICA.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A novel nonlinear combination process monitoring method was proposed based on techniques with memory effect (multivariate exponentially weighted moving average (MEWMA)) and kernel independent component analysis (KICA). The method was developed for dealing with nonlinear issues and detecting small or moderate drifts in one or more process variables with autocorrelation. MEWMA charts use additional information from the past history of the process for keeping the memory effect of the process behavior trend. KICA is a recently developed statistical technique for revealing hidden, nonlinear statistically independent factors that underlie sets of measurements and it is a two-phase algorithm: whitened kernel principal component analysis (KPCA) plus independent component analysis (ICA). The application to the fluid catalytic cracking unit (FCCU) simulated process indicates that the proposed combined method based on MEWMA and KICA can effectively capture the nonlinear relationship and detect small drifts in process variables. Its performance significantly outperforms monitoring method based on ICA, MEWMA-ICA and KICA, especially for long-term performance deterioration.
Cai, Wenshan
2016-09-01
Metamaterials have offered not only the unprecedented opportunity to generate unconventional electromagnetic properties that are not found in nature, but also the exciting potential to create customized nonlinear media with tailored high-order effects. Two particularly compelling directions of current interests are active metamaterials, where the optical properties can be purposely manipulated by external stimuli, and nonlinear metamaterials, which enable intensity-dependent frequency conversion of light. By exploring the interaction of these two directions, we leverage the electrical and optical functions simultaneously supported in nanostructured metals and demonstrate electrically-controlled nonlinear processes from photonic metamaterials. We show that a variety of nonlinear optical phenomena, including the wave mixing and the optical rectification, can be purposely modulated by applied voltage signals. In addition, electrically-induced and voltage-controlled nonlinear effects facilitate us to demonstrate the backward phase matching in a negative index material, a long standing prediction in nonlinear metamaterials. Other results to be covered in this talk include photon-drag effect in plasmonic metamaterials and ion-assisted nonlinear effects from metamaterials in electrolytes. Our results reveal a grand opportunity to exploit optical metamaterials as self-contained, dynamic electrooptic systems with intrinsically embedded electrical functions and optical nonlinearities. Reference: L. Kang, Y. Cui, S. Lan, S. P. Rodrigues, M. L. Brongersma, and W. Cai, Nature Communications, 5, 4680 (2014). S. P. Rodrigues and W.Cai, Nature Nanotechnology, 10, 387 (2015). S. Lan, L. Kang, D. T. Schoen, S. P. Rodrigues, Y. Cui, M. L. Brongersma, and W. Cai, Nature Materials, 14, 807 (2015).
Hippotherapy acute impact on heart rate variability non-linear dynamics in neurological disorders.
Cabiddu, Ramona; Borghi-Silva, Audrey; Trimer, Renata; Trimer, Vitor; Ricci, Paula Angélica; Italiano Monteiro, Clara; Camargo Magalhães Maniglia, Marcela; Silva Pereira, Ana Maria; Rodrigues das Chagas, Gustavo; Carvalho, Eliane Maria
2016-05-15
Neurological disorders are associated with autonomic dysfunction. Hippotherapy (HT) is a therapy treatment strategy that utilizes a horse in an interdisciplinary approach for the physical and mental rehabilitation of people with physical, mental and/or psychological disabilities. However, no studies have been carried out which evaluated the effects of HT on the autonomic control in these patients. Therefore, the objective of the present study was to investigate the effects of a single HT session on cardiovascular autonomic control by time domain and non-linear analysis of heart rate variability (HRV). The HRV signal was recorded continuously in twelve children affected by neurological disorders during a HT session, consisting in a 10-minute sitting position rest (P1), a 15-minute preparatory phase sitting on the horse (P2), a 15-minute HT session (P3) and a final 10-minute sitting position recovery (P4). Time domain and non-linear HRV indices, including Sample Entropy (SampEn), Lempel-Ziv Complexity (LZC) and Detrended Fluctuation Analysis (DFA), were calculated for each treatment phase. We observed that SampEn increased during P3 (SampEn=0.56±0.10) with respect to P1 (SampEn=0.40±0.14, p<0.05), while DFA decreased during P3 (DFA=1.10±0.10) with respect to P1 (DFA=1.26±0.14, p<0.05). A significant SDRR increase (p<0.05) was observed during the recovery period P4 (SDRR=50±30ms) with respect to the HT session period P3 (SDRR=30±10ms). Our results suggest that HT might benefit children with disabilities attributable to neurological disorders by eliciting an acute autonomic response during the therapy and during the recovery period.
Nonlinear short-term heart rate variability prediction of spontaneous ventricular tachyarrhythmia
Institute of Scientific and Technical Information of China (English)
ZHUANG JianJun; NING XinBao; DU SiDan; WANG ZhenZhou; HUO ChengYu; YANG Xi; FAN AiHua
2008-01-01
As malign ventricular tachyarrhythmias triggering sudden cardiac death (SCD),both ventricular tachycardia (VT) and ventricular fibrillation (VF) are major causes of mortality.The most efficient ther-apy for SCD prevention is implantable cardioverter defibrillators (ICD).The ICD can accurately and ef-fectively identify the forthcoming of fatal ventricular tachyarrhythmias and deliver a shock in order to restore patients' normal sinus rhythm.In this study,two nonlinear complexity measures based on en-tropy:approximate entropy (ApEn) and sample entropy (SampEn) as well as two time linear indices:the mean RR interval (the average of time intervals between consecutive R-waves) and the standard devia-tion of RR intervals were used for short-term forecasting of VT-VF occurrence.The last small sections of interbeat intervals preceding 135 VT-VF episodes from 78 patients stored by the ICD were analyzed and compared with individually acquired control time series (CON series) from the same patients,which are normally intrinsic sinus rhythms.The results demonstrate that in addition to an obvious in-crease in heart rates of the patients,the values of two entropy measures are significantly smaller for VT-VF episodes than those for CON series.Conclusions can be drawn that when a ventricular tach-yarrhythmia approaches,the sympathetic tone of the patients is increased,and the complexity of their RR intervals immediately before the onset of VT-VF events is obviously lower than that of RR Intervals recorded during sinus rhythms.For a better separation,the optimal range of threshold r is determined for two algorithms.ApEn and SampEn measures might be the suitable nonlinear parameters for shod-term prediction of life-threatening ventricular tachyarrhythmias in the application of the cardioversion and defibrillation.
The effect of process delay on dynamical behaviors in a self-feedback nonlinear oscillator
Yao, Chenggui; Ma, Jun; Li, Chuan; He, Zhiwei
2016-10-01
The delayed feedback loops play a crucial role in the stability of dynamical systems. The effect of process delay in feedback is studied numerically and theoretically in the delayed feedback nonlinear systems including the neural model, periodic system and chaotic oscillator. The process delay is of key importance in determining the evolution of systems, and the rich dynamical phenomena are observed. By introducing a process delay, we find that it can induce bursting electric activities in the neural model. We demonstrate that this novel regime of amplitude death also exists in the parameter space of feedback strength and process delay for the periodic system and chaotic oscillator. Our results extend the effect of process delay in the paper of Zou et al.(2013) where the process delay can eliminate the amplitude death of the coupled nonlinear systems.
Nonlinear signal processing of electroencephalograms for automated sleep monitoring
Wilson, D.; Rowlands, D. D.; James, Daniel A.; Cutmore, T.
2005-02-01
An automated classification technique is desirable to identify the different stages of sleep. In this paper a technique for differentiating the characteristics of each sleep phase has been developed. This is an ideal pre-processor stage for classifying systems such as neural networks. A wavelet based continuous Morlet transform was developed to analyse the EEG signal in both the time and frequency domain. Test results using two 100 epoch EEG test data sets from pre-recorded EEG data are presented. Key rhythms in the EEG signal were identified and classified using the continuous wavelet transform. The wavelet results indicated each sleep phase contained different rhythms and artefacts (noise from muscle movement in the EEG); providing proof that an EEG can be classified accordingly. The coefficients founded by the wavelet transform have been emphasised by statistical techniques. Hypothesis testing was used to highlight major differences between adjacent sleep stages. Various signal processing methods such as power spectrum density and the discrete wavelet transform have been used to emphasise particular characteristics in an EEG. By implementing signal processing methods on an EEG data set specific rules for each sleep stage have been developed suitable for a neural network classification solution.
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Quasi-likelihood nonlinear models (QLNM) include generalized linear models as a special case.Under some regularity conditions,the rate of the strong consistency of the maximum quasi-likelihood estimation (MQLE) is obtained in QLNM.In an important case,this rate is O(n-1/2(loglogn)1/2),which is just the rate of LIL of partial sums for I.I.d variables,and thus cannot be improved anymore.
Non-linear, adaptive array processing for acoustic interference suppression.
Hoppe, Elizabeth; Roan, Michael
2009-06-01
A method is introduced where blind source separation of acoustical sources is combined with spatial processing to remove non-Gaussian, broadband interferers from space-time displays such as bearing track recorder displays. This differs from most standard techniques such as generalized sidelobe cancellers in that the separation of signals is not done spatially. The algorithm performance is compared to adaptive beamforming techniques such as minimum variance distortionless response beamforming. Simulations and experiments using two acoustic sources were used to verify the performance of the algorithm. Simulations were also used to determine the effectiveness of the algorithm under various signal to interference, signal to noise, and array geometry conditions. A voice activity detection algorithm was used to benchmark the performance of the source isolation.
Ultrafast nonlinear all-optical processes in silicon-on-insulator waveguides
Dekker, R.; Usechak, N.; Först, M.; Driessen, A.
2007-01-01
In this review we present an overview of the progress made in recent years in the field of integrated silicon-on-insulator (SOI) waveguide photonics with a strong emphasis on third-order nonlinear optical processes. Although the focus is on simple waveguide structures the utilization of complex stru
Scene matching based on non-linear pre-processing on reference image and sensed image
Institute of Scientific and Technical Information of China (English)
Zhong Sheng; Zhang Tianxu; Sang Nong
2005-01-01
To solve the heterogeneous image scene matching problem, a non-linear pre-processing method for the original images before intensity-based correlation is proposed. The result shows that the proper matching probability is raised greatly. Especially for the low S/N image pairs, the effect is more remarkable.
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
Making use of disk targets composed of several peculiar materials (foam Au, foam C8H8)and hohlraum with a special structure, experiments have been done at"Xing Guang - II" laser facility,which study the characteristics of hot electrons and therelated nonlinear processes such as StimulatedRaman Scattering (SRS), Two Plasma Decay (TPD), StimulatedBrillouin Scattering (SBS), etc.
Garcia-Retamero, Rocio; Hoffrage, Ulrich; Dieckmann, Anja; Ramos, Manuel
2007-01-01
Three experiments investigated whether participants used Take The Best (TTB) Configural, a fast and frugal heuristic that processes configurations of cues when making inferences concerning which of two alternatives has a higher criterion value. Participants were presented with a compound cue that was nonlinearly separable from its elements. The…
Directory of Open Access Journals (Sweden)
David E. Allen
2016-03-01
Full Text Available This paper features an analysis of major currency exchange rate movements in relation to the US dollar, as constituted in US dollar terms. Euro, British pound, Chinese yuan, and Japanese yen are modelled using a variety of non-linear models, including smooth transition regression models, logistic smooth transition regressions models, threshold autoregressive models, nonlinear autoregressive models, and additive nonlinear autoregressive models, plus Neural Network models. The models are evaluated on the basis of error metrics for twenty day out-of-sample forecasts using the mean average percentage errors (MAPE. The results suggest that there is no dominating class of time series models, and the different currency pairs relationships with the US dollar are captured best by neural net regression models, over the ten year sample of daily exchange rate returns data, from August 2005 to August 2015.
Directory of Open Access Journals (Sweden)
Nadhem Selmi
2015-02-01
Full Text Available The aim of this paper is to study the dynamics of the real exchange rate deviations of G7 countries by capturing nonlinearity and long memory features. In this context, we used fractionally integrated STAR (FISTAR models proposed by Van Dijk et al. (2002 [Van Dijk, D., Franses, P.H., Paap, R., (2002, A nonlinear long-memory model with an application to US unemployment, Journal of Econometrics, 110, 135-165.] for a case with an exponential transition function. Indeed, this study can take into account procedures characterized by several dynamic regimes and persistence phenomena. Empirically, the elements of both fractional long memory and threshold non-linearity are present for the real exchange rates of the G-7 countries against the US, notably in the EU countries.
Nonlinear temperature effects on multifractal complexity of metabolic rate of mice
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Fabio A. Labra
2016-10-01
Full Text Available Complex physiological dynamics have been argued to be a signature of healthy physiological function. Here we test whether the complexity of metabolic rate fluctuations in small endotherms decreases with lower environmental temperatures. To do so, we examine the multifractal temporal scaling properties of the rate of change in oxygen consumption r(VO2, in the laboratory mouse Mus musculus, assessing their long range correlation properties across seven different environmental temperatures, ranging from 0 °C to 30 °C. To do so, we applied multifractal detrended fluctuation analysis (MF-DFA, finding that r(VO2 fluctuations show two scaling regimes. For small time scales below the crossover time (approximately 102 s, either monofractal or weak multifractal dynamics are observed depending on whether Ta 15 °C respectively. For larger time scales, r(VO2 fluctuations are characterized by an asymptotic scaling exponent that indicates multifractal anti-persistent or uncorrelated dynamics. For both scaling regimes, a generalization of the multiplicative cascade model provides very good fits for the Renyi exponents τ(q, showing that the infinite number of exponents h(q can be described by only two independent parameters, a and b. We also show that the long-range correlation structure of r(VO2 time series differs from randomly shuffled series, and may not be explained as an artifact of stochastic sampling of a linear frequency spectrum. These results show that metabolic rate dynamics in a well studied micro-endotherm are consistent with a highly non-linear feedback control system.
Nonlinear temperature effects on multifractal complexity of metabolic rate of mice
Bogdanovich, Jose M.; Bozinovic, Francisco
2016-01-01
Complex physiological dynamics have been argued to be a signature of healthy physiological function. Here we test whether the complexity of metabolic rate fluctuations in small endotherms decreases with lower environmental temperatures. To do so, we examine the multifractal temporal scaling properties of the rate of change in oxygen consumption r(VO2), in the laboratory mouse Mus musculus, assessing their long range correlation properties across seven different environmental temperatures, ranging from 0 °C to 30 °C. To do so, we applied multifractal detrended fluctuation analysis (MF-DFA), finding that r(VO2) fluctuations show two scaling regimes. For small time scales below the crossover time (approximately 102 s), either monofractal or weak multifractal dynamics are observed depending on whether Ta 15 °C respectively. For larger time scales, r(VO2) fluctuations are characterized by an asymptotic scaling exponent that indicates multifractal anti-persistent or uncorrelated dynamics. For both scaling regimes, a generalization of the multiplicative cascade model provides very good fits for the Renyi exponents τ(q), showing that the infinite number of exponents h(q) can be described by only two independent parameters, a and b. We also show that the long-range correlation structure of r(VO2) time series differs from randomly shuffled series, and may not be explained as an artifact of stochastic sampling of a linear frequency spectrum. These results show that metabolic rate dynamics in a well studied micro-endotherm are consistent with a highly non-linear feedback control system.
Analytical investigation of machining chatter by considering the nonlinearity of process damping
Ahmadi, Keivan
2017-04-01
In this paper, the well-established problem of self-excited vibrations in machining is revisited to include the nonlinearity of process damping at the tool and workpiece interface. Machining dynamics is modeled using a time-delayed system with nonlinear damping, and the method of averaging is used to obtain the amplitude of the resulting limit cycles. As a result, an analytical relationship is presented to establish the stability charts corresponding with arbitrary limit cycles in machining systems. The presented analytical solutions are verified using experiments and numerical solutions.
2-D nonlinear IIR-filters for image processing - An exploratory analysis
Bauer, P. H.; Sartori, M.
1991-01-01
A new nonlinear IIR filter structure is introduced and its deterministic properties are analyzed. It is shown to be better suited for image processing applications than its linear shift-invariant counterpart. The new structure is obtained from causality inversion of a 2D quarterplane causal linear filter with respect to the two directions of propagation. It is demonstrated, that by using this design, a nonlinear 2D lowpass filter can be constructed, which is capable of effectively suppressing Gaussian or impulse noise without destroying important image information.
Institute of Scientific and Technical Information of China (English)
Xiao Huang; Jian Wang; Ling-zhi Zhang; Zhi-gang Cai; Zhao-xi Lianga
2001-01-01
Four phenoxysilicon networks for nonlinear optical (NLO) applications were designed and prepared by an extended sol-gel process without additional H20 and catalyst. All poled polymer network films possess high second-order nonlinear optical coefficients (d33) of 10-?～10-8 esu. The investigation of NLO temporal stability at room temperature and elevated temperature (120°C) indicated that these films exhibit high d33 stability because the orientation of the chromophores are locked in the phenoxysilicon organic/inorganic networks.
2-D nonlinear IIR-filters for image processing - An exploratory analysis
Bauer, P. H.; Sartori, M.
1991-01-01
A new nonlinear IIR filter structure is introduced and its deterministic properties are analyzed. It is shown to be better suited for image processing applications than its linear shift-invariant counterpart. The new structure is obtained from causality inversion of a 2D quarterplane causal linear filter with respect to the two directions of propagation. It is demonstrated, that by using this design, a nonlinear 2D lowpass filter can be constructed, which is capable of effectively suppressing Gaussian or impulse noise without destroying important image information.
Strain rate effect in high-speed wire drawing process
He, S.; Van Houtte, P.; Van Bael, A.; Mei, F.; Sarban, A.; Boesman, P.; Galvez, F.; Atienza, J. M.
2002-05-01
This paper presents a study on the strain rate effect during high-speed wire drawing process by means of finite element simulation. Based on the quasistatic stresses obtained by normal tensile tests and dynamic stresses at high strain rates by split Hopkinson pressure bar tests, the wire drawing process was simulated for low carbon steel and high carbon steel. The results show that both the deformation process and the final properties of drawn wires are influenced by the strain rate.
CONTROL OF NONLINEAR PROCESS USING NEURAL NETWORK BASED MODEL PREDICTIVE CONTROL
Directory of Open Access Journals (Sweden)
Dr.A.TRIVEDI
2011-04-01
Full Text Available This paper presents a Neural Network based Model Predictive Control (NNMPC strategy to control nonlinear process. Multilayer Perceptron Neural Network (MLP is chosen to represent a Nonlinear Auto Regressive with eXogenous signal (NARX model of a nonlinear system. NARX dynamic model is based on feed-forward architecture and offers good approximation capabilities along with robustness and accuracy. Based on the identified neural model, a generalized predictive control (GPC algorithm is implemented to control the composition in acontinuous stirred tank reactor (CSTR, whose parameters are optimally determined by solving quadratic performance index using well known Levenberg-Marquardt and Quasi-Newton algorithm. NNMPC is tuned by selecting few horizon parameters and weighting factor. The tracking performance of the NNMPC is tested using different amplitude function as a reference signal on CSTR application. Also the robustness and performance is tested in the presence of disturbance on random reference signal.
Hydex Glass and Amorphous Silicon for Integrated Nonlinear Optical Signal Processing
Morandotti, Roberto
2015-01-01
Photonic integrated circuits that exploit nonlinear optics in order to generate and process signals all-optically have achieved performance far superior to that possible electronically - particularly with respect to speed. Although silicon-on-insulator has been the leading platform for nonlinear optics for some time, its high two-photon absorption at telecommunications wavelengths poses a fundamental limitation. We review the recent achievements based in new CMOS-compatible platforms that are better suited than SOI for nonlinear optics, focusing on amorphous silicon and Hydex glass. We highlight their potential as well as the challenges to achieving practical solutions for many key applications. These material systems have opened up many new capabilities such as on-chip optical frequency comb generation and ultrafast optical pulse generation and measurement.
Chen, Yun; Yang, Hui
2016-06-01
Many real-world systems are evolving over time and exhibit dynamical behaviors. In order to cope with system complexity, sensing devices are commonly deployed to monitor system dynamics. Online sensing brings the proliferation of big data that are nonlinear and nonstationary. Although there is rich information on nonlinear dynamics, significant challenges remain in realizing the full potential of sensing data for system control. This paper presents a new approach of heterogeneous recurrence analysis for online monitoring and anomaly detection in nonlinear dynamic processes. A partition scheme, named as Q-tree indexing, is firstly introduced to delineate local recurrence regions in the multi-dimensional continuous state space. Further, we design a new fractal representation of state transitions among recurrence regions, and then develop new measures to quantify heterogeneous recurrence patterns. Finally, we develop a multivariate detection method for on-line monitoring and predictive control of process recurrences. Case studies show that the proposed approach not only captures heterogeneous recurrence patterns in the transformed space, but also provides effective online control charts to monitor and detect dynamical transitions in the underlying nonlinear processes.
Mendonca, Goncalo V; Heffernan, Kevin S; Rossow, Lindy; Guerra, Myriam; Pereira, Fernando D; Fernhall, Bo
2010-08-01
Women demonstrate greater RR interval variability than men of similar age. Enhanced parasympathetic input into cardiac regulation appears to be not only greater in women, but also protective during periods of cardiac stress. Even though women may have a more favorable autonomic profile after exercise, little research has been conducted on this issue. This study was designed to examine the cardiac autonomic response, in both male and female participants, during the early recovery from supramaximal exercise. Twenty-five individuals, aged 20 to 33 years (13 males and 12 females), performed a 30-s Wingate test. Beat-to-beat RR series were recorded before and 5 min after exercise, with the participants in the supine position and under paced breathing. Linear (spectral analysis) and nonlinear analyses (detrended fluctuation analysis (DFA)) were performed on the same RR series. At rest, women presented lower raw low frequency (LF) power and higher normalized high frequency (HF) power. Under these conditions, the LF/HF ratio of women was also lower than that of men (pheart rate variability (HRV) (pchange in LF/HF ratio and α1 than men from rest to recovery. This study demonstrates that the cardiac autonomic function of women is more affected by supramaximal exercise than that of men. Additionally, DFA did not provide additional information about sexual dimorphisms, compared with conventional spectral HRV techniques.
A high repetition rate experimental setup for quantum non-linear optics with cold Rydberg atoms
Busche, Hannes; Ball, Simon W.; Huillery, Paul
2016-12-01
Using electromagnetically induced transparency and photon storage, the strong dipolar interactions between Rydberg atoms and the resulting dipole blockade can be mapped onto light fields to realise optical non-linearities and interactions at the single photon level. We report on the realisation of an experimental apparatus designed to study interactions between single photons stored as Rydberg excitations in optically trapped microscopic ensembles of ultracold 87Rb atoms. A pair of in-vacuum high numerical aperture lenses focus excitation and trapping beams down to 1 μm, well below the Rydberg blockade. Thanks to efficient magneto-optical trap (MOT) loading from an atomic beam generated by a 2D MOT and the ability to recycle the microscopic ensembles more than 20000 times without significant atom loss, we achieve effective repetition rates exceeding 110 kHz to obtain good photon counting statistics on reasonable time scales. To demonstrate the functionality of the setup, we present evidence of strong photon interactions including saturation of photon storage and the retrieval of non-classical light. Using in-vacuum antennae operating at up to 40 GHz, we perform microwave spectroscopy on photons stored as Rydberg excitations and observe an interaction induced change in lineshape depending on the number of stored photons.
Study of Heart Rate Variability in bipolar disorder: linear and nonlinear parameters during sleep
Directory of Open Access Journals (Sweden)
Matteo eMigliorini
2012-01-01
Full Text Available In the present paper we propose a methodology for the assessment of the autonomic nervous system (ANS in patients affected by bipolar disorder. ANS was explored by means heart rate variability (HRV analysis carried out during night recordings through the evaluation of many different parameters in the time and in the frequency domain, linear and non-linear. The recording of the signals was performed by a wearable sensorized T-shirt. HRV with movement analysis allowed also sleep staging and the estimation of REM sleep percentage over the total sleep time. A group of 8 normal female constituted the control group, on which normality ranges were estimated. One pathologic subject was recorded during four different nights, at time intervals of at least one week, and during different phases of the disturbance. Some of the calculated parameters (MEANNN, SDNN, RMSSD confirmed reduced HRV in depression and bipolar disorder. REM sleep percentage was found to be increased. LZC (Lempel Ziv complexity and SampEn (Sample Entropy, on the other hand, seem to correlate with the depression level. Even if the number of examined subjects is small, and the results need further validation, the proposed methodology and the calculated parameters seem promising tools for the monitoring of mood changes in psychiatric disorders.
Circuits and systems based on delta modulation linear, nonlinear and mixed mode processing
Zrilic, Djuro G
2005-01-01
This book is intended for students and professionals who are interested in the field of digital signal processing of delta-sigma modulated sequences. The overall focus is on the development of algorithms and circuits for linear, non-linear, and mixed mode processing of delta-sigma modulated pulse streams. The material presented here is directly relevant to applications in digital communication, DSP, instrumentation, and control.
Rius, Manuel; Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José
2015-05-18
We experimentally demonstrate, for the first time, a chirped microwave pulses generator based on the processing of an incoherent optical signal by means of a nonlinear dispersive element. Different capabilities have been demonstrated such as the control of the time-bandwidth product and the frequency tuning increasing the flexibility of the generated waveform compared to coherent techniques. Moreover, the use of differential detection improves considerably the limitation over the signal-to-noise ratio related to incoherent processing.
ENTROPY PRODUCTION RATE OF THE MINIMAL DIFFUSION PROCESS
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The entropy production rate of stationary minimal diffusion processes with smooth coefficients is calculated. As a byproduct, the continuity of paths of the minimal diffusion processes is discussed, and that the point at infinity is absorbing is proved.
Mujica-Parodi, L R; Yeragani, Vikram; Malaspina, Dolores
2005-01-01
Heart rate variability (HRV) reflects functioning of the autonomic nervous system and possibly also regulation by the neural limbic system, abnormalities of which have both figured prominently in various etiological models of schizophrenia, particularly those that address patients' vulnerability to stress in connection to psychosis onset and exacerbation. This study provides data on cardiac functioning in a sample of schizophrenia patients that were either medication free or on atypical antipsychotics, as well as cardiac data on matched healthy controls. We included a medication-free group to investigate whether abnormalities in HRV previously reported in the literature and associated with atypical antipsychotics were solely the effect of medications or whether they might be a feature of the illness (or psychosis) itself. We collected 24-hour ECGs on 19 patients and 24 controls. Of the patients, 9 were medication free and 10 were on atypical antipsychotics. All subject groups were matched for age and gender. Patient groups showed equivalent symptom severity and type, as well as duration of illness. We analyzed the data using nonlinear complexity (symbolic dynamic) HRV analyses as well as standard and relative spectral analyses. For the medication-free patients as compared to the healthy controls, our data show decreased R-R intervals during sleep, and abnormal suppression of all frequency ranges, but particularly the low frequency range, which persisted even after adjusting the spectral data for the mean R-R interval. This effect was exacerbated for patients on atypical antipsychotics. Likewise, nonlinear complexity analysis showed significantly impaired HRV for medication-free patients that was exacerbated in the patients on atypical antipsychotics. Altogether, the data suggest a pattern of significantly decreased cardiac vagal function of patients with schizophrenia as compared to healthy controls, apart from and beyond any differences due to medication side
Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities
Energy Technology Data Exchange (ETDEWEB)
Wang, Lifan; Strovink, Mark; Conley, Alexander; Goldhaber,Gerson; Kowalski, Marek; Perlmutter, Saul; Siegrist, James
2005-12-14
Published B and V fluxes from nearby Type Ia supernova are fitted to light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a post-maximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B{sub max} and B{sub BV}. Their difference varies systematically with decline rate {Delta}m{sub 15} in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of B{sub max} itself. A Hubble fit to the average of B{sub max} and B{sub BV} requires a systematic correction for observed B-V color that can be described by a linear coefficient R = 2.59 {+-} 0.24, well below the coefficient R{sub B} {approx} 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, B{sub max} and B{sub BV} exhibit mutual rms intrinsic variation equal to 0.074 {+-} 0.019 mag, of which at least an equal share likely belongs to B{sub BV}. SN magnitudes measured using maximum-luminosity or cmagic methods show comparable rms deviations of order {approx}0.14 mag from the Hubble line. The same fit also establishes a 95% confidence upper limit of 486 km s{sup -1} on the rms peculiar velocity of nearby SNe relative to the Hubble flow.
Neubert, M.; Winkler, J.
2012-12-01
This contribution continues an article series [1,2] about the nonlinear model-based control of the Czochralski crystal growth process. The key idea of the presented approach is to use a sophisticated combination of nonlinear model-based and conventional (linear) PI controllers for tracking of both, crystal radius and growth rate. Using heater power and pulling speed as manipulated variables several controller structures are possible. The present part tries to systematize the properties of the materials to be grown in order to get unambiguous decision criteria for a most profitable choice of the controller structure. For this purpose a material specific constant M called interface mobility and a more process specific constant S called system response number are introduced. While the first one summarizes important material properties like thermal conductivity and latent heat the latter one characterizes the process by evaluating the average axial thermal gradients at the phase boundary and the actual growth rate at which the crystal is grown. Furthermore these characteristic numbers are useful for establishing a scheduling strategy for the PI controller parameters in order to improve the controller performance. Finally, both numbers give a better understanding of the general thermal system dynamics of the Czochralski technique.
Truccolo, Wilson
2017-01-01
Point process generalized linear models (PP-GLMs) provide an important statistical framework for modeling spiking activity in single-neurons and neuronal networks. Stochastic stability is essential when sampling from these models, as done in computational neuroscience to analyze statistical properties of neuronal dynamics and in neuro-engineering to implement closed-loop applications. Here we show, however, that despite passing common goodness-of-fit tests, PP-GLMs estimated from data are often unstable, leading to divergent firing rates. The inclusion of absolute refractory periods is not a satisfactory solution since the activity then typically settles into unphysiological rates. To address these issues, we derive a framework for determining the existence and stability of fixed points of the expected conditional intensity function (CIF) for general PP-GLMs. Specifically, in nonlinear Hawkes PP-GLMs, the CIF is expressed as a function of the previous spike history and exogenous inputs. We use a mean-field quasi-renewal (QR) approximation that decomposes spike history effects into the contribution of the last spike and an average of the CIF over all spike histories prior to the last spike. Fixed points for stationary rates are derived as self-consistent solutions of integral equations. Bifurcation analysis and the number of fixed points predict that the original models can show stable, divergent, and metastable (fragile) dynamics. For fragile models, fluctuations of the single-neuron dynamics predict expected divergence times after which rates approach unphysiologically high values. This metric can be used to estimate the probability of rates to remain physiological for given time periods, e.g., for simulation purposes. We demonstrate the use of the stability framework using simulated single-neuron examples and neurophysiological recordings. Finally, we show how to adapt PP-GLM estimation procedures to guarantee model stability. Overall, our results provide a
Shi, Ping; Yu, Hongliu
2014-04-01
Calculation of linear parameters, such as time-domain and frequency-domain analysis of heart rate variability (HRV), is a conventional method for assessment of autonomic nervous system activity. Nonlinear phenomena are certainly involved in the genesis of HRV. In a seemingly random signal the Poincaré plot can easily demonstrate whether there is an underlying determinism in the signal. Linear and nonlinear analysis methods were applied in the computer words inputting experiments in this study for physiological measurement. This study therefore demonstrated that Poincaré plot was a simple but powerful graphical tool to describe the dynamics of a system.
Institute of Scientific and Technical Information of China (English)
唐圣金; 郭晓松; 于传强; 周志杰; 周召发; 张邦成
2014-01-01
Real time remaining useful life (RUL) prediction based on condition monitoring is an essential part in condition based maintenance (CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item’s individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.
Soft sensor modeling based on variable partition ensemble method for nonlinear batch processes
Wang, Li; Chen, Xiangguang; Yang, Kai; Jin, Huaiping
2017-01-01
Batch processes are always characterized by nonlinear and system uncertain properties, therefore, the conventional single model may be ill-suited. A local learning strategy soft sensor based on variable partition ensemble method is developed for the quality prediction of nonlinear and non-Gaussian batch processes. A set of input variable sets are obtained by bootstrapping and PMI criterion. Then, multiple local GPR models are developed based on each local input variable set. When a new test data is coming, the posterior probability of each best performance local model is estimated based on Bayesian inference and used to combine these local GPR models to get the final prediction result. The proposed soft sensor is demonstrated by applying to an industrial fed-batch chlortetracycline fermentation process.
Design and implementation of non-linear image processing functions for CMOS image sensor
Musa, Purnawarman; Sudiro, Sunny A.; Wibowo, Eri P.; Harmanto, Suryadi; Paindavoine, Michel
2012-11-01
Today, solid state image sensors are used in many applications like in mobile phones, video surveillance systems, embedded medical imaging and industrial vision systems. These image sensors require the integration in the focal plane (or near the focal plane) of complex image processing algorithms. Such devices must meet the constraints related to the quality of acquired images, speed and performance of embedded processing, as well as low power consumption. To achieve these objectives, low-level analog processing allows extracting the useful information in the scene directly. For example, edge detection step followed by a local maxima extraction will facilitate the high-level processing like objects pattern recognition in a visual scene. Our goal was to design an intelligent image sensor prototype achieving high-speed image acquisition and non-linear image processing (like local minima and maxima calculations). For this purpose, we present in this article the design and test of a 64×64 pixels image sensor built in a standard CMOS Technology 0.35 μm including non-linear image processing. The architecture of our sensor, named nLiRIC (non-Linear Rapid Image Capture), is based on the implementation of an analog Minima/Maxima Unit. This MMU calculates the minimum and maximum values (non-linear functions), in real time, in a 2×2 pixels neighbourhood. Each MMU needs 52 transistors and the pitch of one pixel is 40×40 mu m. The total area of the 64×64 pixels is 12.5mm2. Our tests have shown the validity of the main functions of our new image sensor like fast image acquisition (10K frames per second), minima/maxima calculations in less then one ms.
Walker, Christoph
2010-01-01
A parameter-dependent model involving nonlinear diffusion for an age-structured population is studied. The parameter measures the intensity of the mortality. A bifurcation approach is used to establish existence of positive equilibrium solutions.
FUZZY IDENTIFIER WITH EXPONENTIAL RATE OF CONVERGENCE FOR NONLINEAR DYNAMIC SYSTEMS
Institute of Scientific and Technical Information of China (English)
2000-01-01
In this paper,fuzzy systems are used as identifiers for unknown nonlinear dynamic systems.The fuzzy identifier can incorporate linguistic knowledge of nonlinear dynamic systems with input-output pairs directly into the design.In the case where there is the modelling error,a new identification algorithm is proposed.It is proved that the fuzzy identifier is globally stable and the identification error converges to zero exponentially fast.
Heart rate and blood pressure response to short-term head-down bed rest: a nonlinear approach.
Balocchi, R; Di Garbo, A; Michelassi, C; Chillemi, S; Varanini, M; Barbi, M; Legramante, J M; Raimondi, G; Zbilut, J P
2000-06-01
Although it is well-known that prolonged exposure to microgravity environment such as in space travel results in derangements of orthostasis, recent evidence suggests that even short-term exposure may have similar effects and parallels such common examples as prolonged bed rest. Whereas spectral analysis of heart rate and systolic blood pressure have been unable to detect changes, we hypothesized that nonlinear indexes may be better able to uncover such perturbations. Eighteen healthy subjects were exposed to 4-hour head-down tilt, and of these, 4 exhibited fainting. Two nonlinear indexes, mutual information and recurrence quantification were used to analyze the data. Only recurrence quantification was able to detect a "decoupling" of heart rate and systolic blood pressure at rest using discriminant analysis (p < 0.05). These results suggest that orthostatic intolerance may be due to a decoupling of heart rate from systolic blood pressure reflexive activity occurring at rest.
Non-linear properties of R-R distributions as a measure of heart rate variability
Energy Technology Data Exchange (ETDEWEB)
Irurzun, I.M.; Bergero, P.; Cordero, M.C.; Defeo, M.M.; Vicente, J.L.; Mola, E.E
2003-06-01
We analyze the dynamic quality of the R-R interbeat intervals of electrocardiographic signals from healthy people and from patients with premature ventricular contractions (PVCs) by applying different measure algorithms to standardised public domain data sets of heart rate variability. Our aim is to assess the utility of these algorithms for the above mentioned purposes. Long and short time series, 24 and 0.50 h respectively, of interbeat intervals of healthy and PVC subjects were compared with the aim of developing a fast method to investigate their temporal organization. Two different methods were used: power spectral analysis and the integral correlation method. Power spectral analysis has proven to be a powerful tool for detecting long-range correlations. If it is applied in a short time series, power spectra of healthy and PVC subjects show a similar behavior, which disqualifies power spectral analysis as a fast method to distinguish healthy from PVC subjects. The integral correlation method allows us to study the fractal properties of interbeat intervals of electrocardiographic signals. The cardiac activity of healthy and PVC people stems from dynamics of chaotic nature characterized by correlation dimensions d{sub f} equal to 3.40{+-}0.50 and 5.00{+-}0.80 for healthy and PVC subjects respectively. The methodology presented in this article bridges the gap between theoretical and experimental studies of non-linear phenomena. From our results we conclude that the minimum number of coupled differential equations to describe cardiac activity must be six and seven for healthy and PVC individuals respectively. From the present analysis we conclude that the correlation integral method is particularly suitable, in comparison with the power spectral analysis, for the early detection of arrhythmias on short time (0.5 h) series.
Heath, Joel P; Gilchrist, H Grant; Ydenberg, Ronald C
2010-10-22
To maximize fitness, animals must respond to a variety of processes that operate at different rates or timescales. Appropriate decisions could therefore involve complex interactions among these processes. For example, eiders wintering in the arctic sea ice must consider locomotion and physiology of diving for benthic invertebrates, digestive processing rate and a nonlinear decrease in profitability of diving as currents increase over the tidal cycle. Using a multi-scale dynamic modelling approach and continuous field observations of individuals, we demonstrate that the strategy that maximizes long-term energy gain involves resting during the most profitable foraging period (slack currents). These counterintuitive foraging patterns are an adaptive trade-off between multiple overlapping rate processes and cannot be explained by classical rate-maximizing optimization theory, which only considers a single timescale and predicts a constant rate of foraging. By reducing foraging and instead digesting during slack currents, eiders structure their activity in order to maximize long-term energetic gain over an entire tide cycle. This study reveals how counterintuitive patterns and a complex functional response can result from a simple trade-off among several overlapping rate processes, emphasizing the necessity of a multi-scale approach for understanding adaptive routines in the wild and evaluating mechanisms in ecological time series.
Liu, Qian; OuYang, Liangfei; Liang, Heng; Li, Nan; Geng, Xindu
2012-06-01
A novel thermodynamic state recursion (TSR) method, which is based on nonequilibrium thermodynamic path described by the Lagrangian-Eulerian representation, is presented to simulate the whole chromatographic process of frontal analysis using the spatial distribution of solute bands in time series like as a series of images. TSR differs from the current numerical methods using the partial differential equations in Eulerian representation. The novel method is used to simulate the nonideal, nonlinear hydrophobic interaction chromatography (HIC) processes of lysozyme and myoglobin under the discrete complex boundary conditions. The results show that the simulated breakthrough curves agree well with the experimental ones. The apparent diffusion coefficient and the Langmuir isotherm parameters of the two proteins in HIC are obtained by the state recursion inverse method. Due to its the time domain and Markov characteristics, TSR is applicable to the design and online control of the nonlinear multicolumn chromatographic systems.
Photonic Damascene Process for Integrated High-Q Microresonator Based Nonlinear Photonics
Pfeiffer, Martin H P; Brasch, Victor; Zervas, Michael; Geiselmann, Michael; Jost, John D; Kippenberg, Tobias J
2015-01-01
High confinement, integrated silicon nitride (SiN) waveguides have recently emerged as attractive platform for on-chip nonlinear optical devices. The fabrication of high-Q SiN microresonators with anomalous group velocity dispersion (GVD) has enabled broadband nonlinear optical frequency comb generation. Such frequency combs have been successfully applied in coherent communication and ultrashort pulse generation. However, the reliable fabrication of high confinement waveguides from stoichiometric, high stress SiN remains challenging. Here we present a novel photonic Damascene fabrication process enabling the use of substrate topography for stress control and thin film crack prevention. With close to unity sample yield we fabricate microresonators with $1.35\\,\\mu\\mathrm{m}$ thick waveguides and optical Q factors of $3.7\\times10^{6}$ and demonstrate single temporal dissipative Kerr soliton (DKS) based coherent optical frequency comb generation. Our newly developed process is interesting also for other material ...
Nonlinear software sensor for monitoring genetic regulation processes with noise and modeling errors
Ibarra-Junquera, V; Rosu, H C; Arguello, G; Collado-Vides, J
2004-01-01
Nonlinear control techniques by means of a software sensor that are commonly used in chemical engineering could be also applied to genetic regulation processes. We provide here a realistic formulation of this procedure by introducing an additive white Gaussian noise, which is usually found in experimental data. Besides, we include model errors, meaning that we assume we do not know the nonlinear regulation function of the process. In order to illustrate this procedure, we employ the Goodwin dynamics of the concentrations (1963) in the simple form recently discussed by De Jong (2002), which involves the dynamics of the mRNA a, given protein A, and metabolite K concentrations. However instead of considering their full dynamics, we use only the data of metabolite K and a designed software sensor. We also show, more generally, that it is possible to rebuild the complete set of n concentrations despite the uncertainties in the regulation function and the perturbation due to the additive white Gaussian noise
The SPH approach to the process of container filling based on non-linear constitutive models
Institute of Scientific and Technical Information of China (English)
Tao Jiang; Jie Ouyang; Lin Zhang; Jin-Lian Ren
2012-01-01
In this work,the transient free surface of container filling with non-linear constitutive equation's fluids is numerically investigated by the smoothed particle hydrodynamics (SPH) method.Specifically,the filling process of a square container is considered for non-linear polymer fluids based on the Cross model.The validity of the presented SPH is first verified by solving the Newtonian fluid and OldroydB fluid jet.Various phenomena in the filling process are shown,including the jet buckling,jet thinning,splashing or spluttering,steady filling.Moreover,a new phenomenon of vortex whirling is more evidently observed for the Cross model fluid compared with the Newtonian fluid case.
Institute of Scientific and Technical Information of China (English)
WANG Yan-bo; BAO Gang
2008-01-01
By applying a nonlinear control and arranging a transient process, the initiative error of the pneumatic servo positioning system is reduced largely, and a larger gain of the controller is used to improve the responding speed of the system at the same damping ratio. Therefore, a compromise is made among the responding speed, overshoot, robustness, adaptability and stability. In addition, a dynamic output feedback controller, including position velocity and acceleration (PVA) feedback, is designed to improve the performance of the system. And a nonlinear controller is reconstructed based on the linear output feedback controller to decrease noises and disturbances. The dynamic responses of the system are simulated and tested. Results show that the error is kept within 0.02 mm under different mass loads and the positioning transient process is smooth, without overshoot and speedy.
Riverman, K. L.; Anandakrishnan, S.; Alley, R. B.; Peters, L. E.; Christianson, K. A.; Muto, A.
2013-12-01
Northeast Greenland Ice Stream (NEGIS) is the largest ice stream in Greenland, draining approximately 8.4% of the ice sheet's area. The flow pattern and stability mechanism of this ice stream are unique to others in Greenland and Antarctica, and merit further study to ascertain the sensitivity of this ice stream to future climate change. Geophysical methods are valuable tools for this application, but their results are sensitive to the structure of the firn and any spatial variations in firn properties across a given study region. Here we present firn data from a 40-km-long seismic profile across the upper reaches of NEGIS, collected in the summer of 2012 as part of an integrated ground-based geophysical survey. We find considerable variations in firn thickness that are coincident with the ice stream shear margins, where a thinner firn layer is present within the margins, and a thicker, more uniform firn layer is present elsewhere in our study region. Higher accumulation rates in the marginal surface troughs due to drift-snow trapping can account for some of this increased densification; however, our seismic results also highlight enhanced anisotropy within the firn and upper ice column that is confined to narrow bands within the shear margins. We thus interpret these large firn thickness variations and abrupt changes in anisotropy as indicators of firn densification dependent on the effective stress state as well as the overburden pressure, suggesting that the strain rate increases nonlinearly with stress across the shear margins. A GPS strain grid maintained for three weeks across both margins observed strong side shearing, with rapid stretching and then compression along particle paths, indicating large deviatoric stresses in the margins. This work demonstrates the importance of developing a high-resolution firn densification model when conducting geophysical field work in regions possessing a complex ice flow history; it also motivates the need for a more
Effects of non-linear rheology on the electrospinning process: a model study
Pontrelli, Giuseppe; Coluzza, Ivan; Pisignano, Dario; Succi, Sauro
2014-01-01
We develop an analytical bead-spring model to investigate the role of non-linear rheology on the dynamics of electrified jets in the early stage of the electrospinning process. Qualitative arguments, parameter studies as well as numerical simulations, show that the elongation of the charged jet filament is significantly reduced in the presence of a non-zero yield stress. This may have beneficial implications for the optimal design of future electrospinning experiments.
Salcedo-Sanz, S.
2016-10-01
Meta-heuristic algorithms are problem-solving methods which try to find good-enough solutions to very hard optimization problems, at a reasonable computation time, where classical approaches fail, or cannot even been applied. Many existing meta-heuristics approaches are nature-inspired techniques, which work by simulating or modeling different natural processes in a computer. Historically, many of the most successful meta-heuristic approaches have had a biological inspiration, such as evolutionary computation or swarm intelligence paradigms, but in the last few years new approaches based on nonlinear physics processes modeling have been proposed and applied with success. Non-linear physics processes, modeled as optimization algorithms, are able to produce completely new search procedures, with extremely effective exploration capabilities in many cases, which are able to outperform existing optimization approaches. In this paper we review the most important optimization algorithms based on nonlinear physics, how they have been constructed from specific modeling of a real phenomena, and also their novelty in terms of comparison with alternative existing algorithms for optimization. We first review important concepts on optimization problems, search spaces and problems' difficulty. Then, the usefulness of heuristics and meta-heuristics approaches to face hard optimization problems is introduced, and some of the main existing classical versions of these algorithms are reviewed. The mathematical framework of different nonlinear physics processes is then introduced as a preparatory step to review in detail the most important meta-heuristics based on them. A discussion on the novelty of these approaches, their main computational implementation and design issues, and the evaluation of a novel meta-heuristic based on Strange Attractors mutation will be carried out to complete the review of these techniques. We also describe some of the most important application areas, in
Molecular Optics Nonlinear Optical Processes in Organic and Polymeric Crystals and Films. Part 2
1991-11-01
susceptibility gamma ijkl(-omega 4; omega 1, omega 2, omega 3 ) demonstrate that the microscopic origin of the nonresonant third order nonlinear optical...interaction calculations of gamma jkl(-omega 4; omega 1, omega 2, omega 3 ) for the archetypal class of quasi-one dimensional conjugated structures...largest of the two dominant, competing virtual excitation processes that determine gamma ijkl(- omega 4; omega 1, omega 2, omega 3 ). It is also found in
Data-driven design of fault diagnosis systems nonlinear multimode processes
Haghani Abandan Sari, Adel
2014-01-01
In many industrial applications early detection and diagnosis of abnormal behavior of the plant is of great importance. During the last decades, the complexity of process plants has been drastically increased, which imposes great challenges in development of model-based monitoring approaches and it sometimes becomes unrealistic for modern large-scale processes. The main objective of Adel Haghani Abandan Sari is to study eﬃcient fault diagnosis techniques for complex industrial systems using process historical data and considering the nonlinear behavior of the process. To this end, diﬀerent methods are presented to solve the fault diagnosis problem based on the overall behavior of the process and its dynamics. Moreover, a novel technique is proposed for fault isolation and determination of the root-cause of the faults in the system, based on the fault impacts on the process measurements. Contents Process monitoring Fault diagnosis and fault-tolerant control Data-driven approaches and decision making Target...
Development of coherent tunable source in 2–16 m region using nonlinear frequency mixing processes
Indian Academy of Sciences (India)
Udit Chatterjee
2014-01-01
A very convenient way to obtain widely tunable source of coherent radiation in the infrared region is through nonlinear frequency mixing processes like second harmonic generation (SHG), difference-frequency mixing (DFM) or optical parametric oscillation (OPO). Using commonly available Nd:YAG laser and its harmonic pumped dye laser radiation as parent beams, we have been able to generate coherent tunable infrared radiation (IR) in 2–16 m region using different nonlinear crystals by DFM and OPO. We have also generated such IR source in the 4–5 m region through SHG of CO2 laser in different infrared crystals. In the process we have characterized a large number of nonlinear crystals like different borate group of crystals, KTP, KTA, LiIO3, MgO:LiNbO3, GaSe, AgGaSe2, ZnGeP2, AgGa1−InSe2, HgGa2S4 etc. To improve the conversion efficiencies of such frequency conversion processes, we have developed some novel schemes, like multipass configuration (MC) and positive optical feedback (POF). The significance of the obtained results lies in the fact that to get the same conversion in SHG or DFM, one now requires fundamental input radiation with much lower intensity.
Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.
1996-01-01
In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.
Markov and semi-Markov processes as a failure rate
Grabski, Franciszek
2016-06-01
In this paper the reliability function is defined by the stochastic failure rate process with a non negative and right continuous trajectories. Equations for the conditional reliability functions of an object, under assumption that the failure rate is a semi-Markov process with an at most countable state space are derived. A proper theorem is presented. The linear systems of equations for the appropriate Laplace transforms allow to find the reliability functions for the alternating, the Poisson and the Furry-Yule failure rate processes.
Frank, T. D.
2008-02-01
We discuss two central claims made in the study by Bassler et al. [K.E. Bassler, G.H. Gunaratne, J.L. McCauley, Physica A 369 (2006) 343]. Bassler et al. claimed that Green functions and Langevin equations cannot be defined for nonlinear diffusion equations. In addition, they claimed that nonlinear diffusion equations are linear partial differential equations disguised as nonlinear ones. We review bottom-up and top-down approaches that have been used in the literature to derive Green functions for nonlinear diffusion equations and, in doing so, show that the first claim needs to be revised. We show that the second claim as well needs to be revised. To this end, we point out similarities and differences between non-autonomous linear Fokker-Planck equations and autonomous nonlinear Fokker-Planck equations. In this context, we raise the question whether Bassler et al.’s approach to financial markets is physically plausible because it necessitates the introduction of external traders and causes. Such external entities can easily be eliminated when taking self-organization principles and concepts of nonextensive thermostatistics into account and modeling financial processes by means of nonlinear Fokker-Planck equations.
Ultrafast nonlinear optical processes in metal-dielectric nanocomposites and nanostructures
Energy Technology Data Exchange (ETDEWEB)
Kim, Kwang-Hyon
2012-04-13
This work reports results of a theoretical study of nonlinear optical processes in metal-dielectric nanocomposites used for the increase of the nonlinear coefficients and for plasmonic field enhancement. The main results include the study of the transient saturable nonlinearity in dielectric composites doped with metal nanoparticles, its physical mechanism as well its applications in nonlinear optics. For the study of the transient response, a time-depending equation for the dielectric function of the nanocomposite using the semi-classical two-temperature model is derived. By using this approach, we study the transient nonlinear characteristics of these materials in comparison with preceding experimental measurements. The results show that these materials behave as efficient saturable absorbers for passive mode-locking of lasers in the spectral range from the visible to near IR. We present results for the modelocked dynamics in short-wavelength solid-state and semiconductor disk lasers; in this spectral range other efficient saturable absorbers do not exist. We suggest a new mechanism for the realization of slow light phenomenon by using glasses doped with metal nanoparticles in a pump-probe regime near the plasmonic resonance. Furthermore, we study femtosecond plasmon generation by mode-locked surface plasmon polariton lasers with Bragg reflectors and metal-gain-absorber layered structures. In the final part of the thesis, we present results for high-order harmonic generation near a metallic fractal rough surface. The results show a possible reduction of the pump intensities by three orders of magnitudes and two orders of magnitudes higher efficiency compared with preceding experimental results by using bow-tie nanostructures.
Hussain, Mirza Zahid; Li, Fuguo; Wang, Jing; Yuan, Zhanwei; Li, Pan; Wu, Tao
2015-07-01
The present study comprises the determination of constitutive relationship for thermo-mechanical processing of INCONEL 718 through double multivariate nonlinear regression, a newly developed approach which not only considers the effect of strain, strain rate, and temperature on flow stress but also explains the interaction effect of these thermo-mechanical parameters on flow behavior of the alloy. Hot isothermal compression experiments were performed on Gleeble-3500 thermo-mechanical testing machine in the temperature range of 1153 to 1333 K within the strain rate range of 0.001 to 10 s-1. The deformation behavior of INCONEL 718 is analyzed and summarized by establishing the high temperature deformation constitutive equation. The calculated correlation coefficient ( R) and average absolute relative error ( AARE) underline the precision of proposed constitutive model.
Kim, Daewook; Kim, Dojin; Hong, Keum-Shik; Jung, Il Hyo
2014-01-01
The first objective of this paper is to prove the existence and uniqueness of global solutions for a Kirchhoff-type wave equation with nonlinear dissipation of the form Ku'' + M(|A (1/2) u|(2))Au + g(u') = 0 under suitable assumptions on K, A, M(·), and g(·). Next, we derive decay estimates of the energy under some growth conditions on the nonlinear dissipation g. Lastly, numerical simulations in order to verify the analytical results are given.
Role of Rate of Specific Growth Rate in Different Growth Processes: A First Principle Approach
Biswas, Dibyendu; Patra, Sankar Nayaran
2015-01-01
In the present communication, effort is given for the development of a common platform that helps to address several growth processes found in literature. Based on first principle approach, the role of rate of specific growth rate in different growth processes has been considered in an unified manner. It is found that different growth equations can be derived from the same rate equation of specific growth rate. The dependence of growth features of different growth processes on the parameters of the rate equation of specific growth rate has been examined in detail. It is found that competitive environment may increase the saturation level of population size. The exponential growth could also be addressed in terms of two important factors of growth dynamics, as reproduction and competition. These features are, most probably, not reported earlier.
Luo, Biao; Wu, Huai-Ning; Li, Han-Xiong
2015-04-01
Highly dissipative nonlinear partial differential equations (PDEs) are widely employed to describe the system dynamics of industrial spatially distributed processes (SDPs). In this paper, we consider the optimal control problem of the general highly dissipative SDPs, and propose an adaptive optimal control approach based on neuro-dynamic programming (NDP). Initially, Karhunen-Loève decomposition is employed to compute empirical eigenfunctions (EEFs) of the SDP based on the method of snapshots. These EEFs together with singular perturbation technique are then used to obtain a finite-dimensional slow subsystem of ordinary differential equations that accurately describes the dominant dynamics of the PDE system. Subsequently, the optimal control problem is reformulated on the basis of the slow subsystem, which is further converted to solve a Hamilton-Jacobi-Bellman (HJB) equation. HJB equation is a nonlinear PDE that has proven to be impossible to solve analytically. Thus, an adaptive optimal control method is developed via NDP that solves the HJB equation online using neural network (NN) for approximating the value function; and an online NN weight tuning law is proposed without requiring an initial stabilizing control policy. Moreover, by involving the NN estimation error, we prove that the original closed-loop PDE system with the adaptive optimal control policy is semiglobally uniformly ultimately bounded. Finally, the developed method is tested on a nonlinear diffusion-convection-reaction process and applied to a temperature cooling fin of high-speed aerospace vehicle, and the achieved results show its effectiveness.
Melillo, Paolo; Bracale, Marcello; Pecchia, Leandro
2011-11-07
This study investigates the variations of Heart Rate Variability (HRV) due to a real-life stressor and proposes a classifier based on nonlinear features of HRV for automatic stress detection. 42 students volunteered to participate to the study about HRV and stress. For each student, two recordings were performed: one during an on-going university examination, assumed as a real-life stressor, and one after holidays. Nonlinear analysis of HRV was performed by using Poincaré Plot, Approximate Entropy, Correlation dimension, Detrended Fluctuation Analysis, Recurrence Plot. For statistical comparison, we adopted the Wilcoxon Signed Rank test and for development of a classifier we adopted the Linear Discriminant Analysis (LDA). Almost all HRV features measuring heart rate complexity were significantly decreased in the stress session. LDA generated a simple classifier based on the two Poincaré Plot parameters and Approximate Entropy, which enables stress detection with a total classification accuracy, a sensitivity and a specificity rate of 90%, 86%, and 95% respectively. The results of the current study suggest that nonlinear HRV analysis using short term ECG recording could be effective in automatically detecting real-life stress condition, such as a university examination.
Directory of Open Access Journals (Sweden)
Melillo Paolo
2011-11-01
Full Text Available Abstract Background This study investigates the variations of Heart Rate Variability (HRV due to a real-life stressor and proposes a classifier based on nonlinear features of HRV for automatic stress detection. Methods 42 students volunteered to participate to the study about HRV and stress. For each student, two recordings were performed: one during an on-going university examination, assumed as a real-life stressor, and one after holidays. Nonlinear analysis of HRV was performed by using Poincaré Plot, Approximate Entropy, Correlation dimension, Detrended Fluctuation Analysis, Recurrence Plot. For statistical comparison, we adopted the Wilcoxon Signed Rank test and for development of a classifier we adopted the Linear Discriminant Analysis (LDA. Results Almost all HRV features measuring heart rate complexity were significantly decreased in the stress session. LDA generated a simple classifier based on the two Poincaré Plot parameters and Approximate Entropy, which enables stress detection with a total classification accuracy, a sensitivity and a specificity rate of 90%, 86%, and 95% respectively. Conclusions The results of the current study suggest that nonlinear HRV analysis using short term ECG recording could be effective in automatically detecting real-life stress condition, such as a university examination.
Predictive Information Rate in Discrete-time Gaussian Processes
Abdallah, Samer A
2012-01-01
We derive expressions for the predicitive information rate (PIR) for the class of autoregressive Gaussian processes AR(N), both in terms of the prediction coefficients and in terms of the power spectral density. The latter result suggests a duality between the PIR and the multi-information rate for processes with mutually inverse power spectra (i.e. with poles and zeros of the transfer function exchanged). We investigate the behaviour of the PIR in relation to the multi-information rate for some simple examples, which suggest, somewhat counter-intuitively, that the PIR is maximised for very `smooth' AR processes whose power spectra have multiple poles at zero frequency. We also obtain results for moving average Gaussian processes which are consistent with the duality conjectured earlier. One consequence of this is that the PIR is unbounded for MA(N) processes.
Multivariable adaptive control and estimation of a nonlinear wastewater treatment process
Energy Technology Data Exchange (ETDEWEB)
Ben Youssef, C.; Dahhou, B. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France)]|[Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France)
1995-12-31
In this paper, an approach for estimating biological state and parameter variables and for controlling a non linear wastewater treatment process is developed. Combination of a nonlinear estimation procedure and a multivariable reference model control law provides favourable performances for tracking a given model-based reference model despite disturbances and system parameter uncertainties. Convergence of both estimation and control scheme are demonstrated via Lyapunov`s method. Simulation study with additive measurements noises and parameter jumps shows the efficiency and significant robustness of the control methodology developed for this non linear process. (author) 13 refs.
De Siena, S; Illuminati, F; Siena, Silvio De; Lisi, Antonio Di; Illuminati, Fabrizio
2002-01-01
We introduce nonlinear canonical transformations that yield effective Hamiltonians of multiphoton down conversion processes, and we define the associated non-Gaussian multiphoton squeezed states as the coherent states of the multiphoton Hamiltonians. We study in detail the four-photon processes and the associated non-Gaussian four-photon squeezed states. The realization of squeezing, the behavior of the field statistics, and the structure of the phase space distributions show that these states realize a natural four-photon generalization of the two-photon squeezed states.
Nonlinear tracking in a diffusion process with a Bayesian filter and the finite element method
DEFF Research Database (Denmark)
Pedersen, Martin Wæver; Thygesen, Uffe Høgsbro; Madsen, Henrik
2011-01-01
A new approach to nonlinear state estimation and object tracking from indirect observations of a continuous time process is examined. Stochastic differential equations (SDEs) are employed to model the dynamics of the unobservable state. Tracking problems in the plane subject to boundaries...... become complicated using SMC because Monte Carlo randomness is introduced. The finite element (FE) method solves the Kolmogorov equations of the SDE numerically on a triangular unstructured mesh for which boundary conditions to the state-space are simple to incorporate. The FE approach to nonlinear state...... estimation is suited for off-line data analysis because the computed smoothed state densities, maximum a posteriori parameter estimates and state sequence are deterministic conditional on the finite element mesh and the observations. The proposed method is conceptually similar to existing point...
Nonlinear dynamics of three-magnon process driven by ferromagnetic resonance in yttrium iron garnet
Energy Technology Data Exchange (ETDEWEB)
Cunha, R. O. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Centro Interdisciplinar de Ciências da Natureza, Universidade Federal da Integração Latino-Americana, 85867-970 Foz do Iguaçu, PR (Brazil); Holanda, J.; Azevedo, A.; Rezende, S. M., E-mail: rezende@df.ufpe.br [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Vilela-Leão, L. H. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Centro Acadêmico do Agreste, Universidade Federal de Pernambuco, 55002-970 Caruaru, PE (Brazil); Rodríguez-Suárez, R. L. [Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago (Chile)
2015-05-11
We report an investigation of the dynamics of the three-magnon splitting process associated with the ferromagnetic resonance (FMR) in films of the insulating ferrimagnet yttrium iron garnet (YIG). The experiments are performed with a 6 μm thick YIG film close to a microstrip line fed by a microwave generator operating in the 2–6 GHz range. The magnetization precession is driven by the microwave rf magnetic field perpendicular to the static magnetic field, and its dynamics is observed by monitoring the amplitude of the FMR absorption peak. The time evolution of the amplitude reveals that if the frequency is lowered below a critical value of 3.3 GHz, the FMR mode pumps two magnons with opposite wave vectors that react back on the FMR, resulting in a nonlinear dynamics of the magnetization. The results are explained by a model with coupled nonlinear equations describing the time evolution of the magnon modes.
Directory of Open Access Journals (Sweden)
Hong Qin
2000-08-01
Full Text Available Collective processes in intense charged particle beams described self-consistently by the Vlasov-Maxwell equations are studied using a 3D multispecies nonlinear perturbative particle simulation method. The newly developed beam equilibrium, stability, and transport (BEST code is used to simulate the nonlinear stability properties of intense beam propagation, surface eigenmodes in a high-intensity beam, and the electron-proton (e-p two-stream instability observed in the Proton Storage Ring (PSR experiment. Detailed simulations in a parameter regime characteristic of the PSR experiment show that the dipole-mode two-stream instability is stabilized by a modest spread (about 0.1% in axial momentum of the beam particles.
Numerical simulation of nonlinear processes in a beam-plasma system
Energy Technology Data Exchange (ETDEWEB)
Efimova, A. A., E-mail: anna.an.efimova@gmail.com; Berendeev, E. A.; Vshivkov, V. A. [Institute of Computational Mathematics and Mathematical Geophysics SB RAS 6 Acad. Lavrentyev Ave., Novosibirsk 630090 (Russian Federation); Dudnikova, G. I. [University of Maryland, College Park, MD 20742 (United States); Institute of Computational Technologies SB RAS, 6 Acad. Lavrentyev Ave., Novosibirsk 630090 (Russian Federation)
2015-10-28
In the present paper we consider the efficiency of the electromagnetic radiation generation due to various nonlinear processes in the beam-plasma system. The beam and plasma parameters were chosen close to the parameters in the experiment on the GOL-3 facility (BINP SB RAS). The model of the collisionless plasma is described by system of the Vlasov-Maxwell equations with periodic boundary conditions. The parallel numerical algorithm is based on the particles-in-cell method (PIC) with mixed Euler-Lagrangian domain decomposition. Various scenarios of nonlinear evolution in the beam-plasma system under the influence of an external magnetic field in case of a low density beam were studied. The energy transfer from one unstable mode to the others modes was observed.
DEFF Research Database (Denmark)
Porto da Silva, Edson
Digital signal processing (DSP) has become one of the main enabling technologies for the physical layer of coherent optical communication networks. The DSP subsystems are used to implement several functionalities in the digital domain, from synchronization to channel equalization. Flexibility...... nonlinearity compensation, (II) spectral shaping, and (III) adaptive equalization. For (I), original contributions are presented to the study of the nonlinearity compensation (NLC) with digital backpropagation (DBP). Numerical and experimental performance investigations are shown for different application...... scenarios. Concerning (II), it is demonstrated how optical and electrical (digital) pulse shaping can be allied to improve the spectral confinement of a particular class of optical time-division multiplexing (OTDM) signals that can be used as a building block for fast signaling single-carrier transceivers...
Anticipation and the Non-linear Dynamics of Meaning-Processing in Social Systems
Leydesdorff, Loet
2009-01-01
Social order does not exist as a stable phenomenon, but can be considered as "an order of reproduced expectations." When anticipations operate upon one another, they can generate a non-linear dynamics which processes meaning. Although specific meanings can be stabilized, for example in social institutions, all meaning arises from a global horizon of possible meanings. Using Luhmann's (1984) social systems theory and Rosen's (1985) theory of anticipatory systems, I submit algorithms for modeling the non-linear dynamics of meaning in social systems. First, a self-referential system can use a model of itself for the anticipation. Under the condition of functional differentiation, the social system can be expected to entertain a set of models; each model can also contain a model of the other models. Two anticipatory mechanisms are then possible: a transversal one between the models, and a longitudinal one providing the system with a variety of meanings. A system containing two anticipatory mechanisms can become h...
Makhal, Krishnandu; Mathur, Paresh; Maurya, Sidharth; Goswami, Debabrata
2017-02-01
Third order nonlinearities of Mn(III)-Phthalocyanine chloride in dimethyl-sulphoxide under 50 fs pulses, operating at 94 MHz, by eliminating cumulative thermal effects have been investigated and reported by us. Modifications were done in data acquisition during Z-scan experiment, which included recording of time evolution waveform traces in an oscilloscope and not collection of Z versus transmission and utilization of a chopper of a suitable duty cycle. Time evolution traces were further processed analytically through MatLab® programming, which yielded Z-scan traces similar to what was obtained with single shot 50 fs pulse. We observed reverse saturable absorption at 800 nm owing to excited state absorption. We show that the nonlinear refractive index (γ) and nonlinear absorption coefficient (β) are over estimated almost 100 times, when MHz pulses are used compared to a situation, where thermo-optical nonlinearities are accounted. Illumination and dark periods are carefully set in a way, so that the sample is able to completely recover its initial temperature before arrival of the next pulse. Magnitudes of γ and β were found to be -(6.5-4.9) × 10-16 m2/W and (5.4-6.2) × 10-10 m/W under the MHz condition, whereas they were -(0.18-2.2) × 10-18 m2/W and (9.5-15) × 10-12 m/W under the thermally managed condition, respectively. To reveal the associated fast nonlinearity, femtosecond transient absorption experiment was performed, which inferred excited state absorption and ground state bleaching across the 450-780 nm region. Dynamics associated with these processes are reported along with fluorescence lifetime obtained through the TCSPC technique. Structure optimization using TDDFT calculations and HOMO-LUMO gaps with orbital pictures are also shown.
Directory of Open Access Journals (Sweden)
Ying-Ying Wang
2015-06-01
Full Text Available The identification difficulties for a dual-rate Hammerstein system lie in two aspects. First, the identification model of the system contains the products of the parameters of the nonlinear block and the linear block, and a standard least squares method cannot be directly applied to the model; second, the traditional single-rate discrete-time Hammerstein model cannot be used as the identification model for the dual-rate sampled system. In order to solve these problems, by combining the polynomial transformation technique with the key variable separation technique, this paper converts the Hammerstein system into a dual-rate linear regression model about all parameters (linear-in-parameter model and proposes a recursive least squares algorithm to estimate the parameters of the dual-rate system. The simulation results verify the effectiveness of the proposed algorithm.
Directory of Open Access Journals (Sweden)
Ying Wang
2014-01-01
Full Text Available We investigate the dynamical behaviors of a class of discrete SIRS epidemic models with nonlinear incidence rate and varying population sizes. The model is required to possess different death rates for the susceptible, infectious, recovered, and constant recruitment into the susceptible class, infectious class, and recovered class, respectively. By using the inductive method, the positivity and boundedness of all solutions are obtained. Furthermore, by constructing new discrete type Lyapunov functions, the sufficient and necessary conditions on the global asymptotic stability of the disease-free equilibrium and endemic equilibrium are established.
High-rate squeezing process of bulk metallic glasses
Fan, Jitang
2017-03-01
High-rate squeezing process of bulk metallic glasses from a cylinder into an intact sheet achieved by impact loading is investigated. Such a large deformation is caused by plastic flow, accompanied with geometrical confinement, shear banding/slipping, thermo softening, melting and joining. Temperature rise during the high-rate squeezing process makes a main effect. The inherent mechanisms are illustrated. Like high-pressure torsion (HPT), equal channel angular pressing (ECAP) and surface mechanical attrition treatments (SMAT) for refining grain of metals, High-Rate Squeezing (HRS), as a multiple-functions technique, not only creates a new road of processing metallic glasses and other metallic alloys for developing advanced materials, but also directs a novel technology of processing, grain refining, coating, welding and so on for treating materials.
Yan, Xuehua
2014-01-01
This paper is the further investigation of work of Yan and Liu, 2011, and considers the global practical tracking problem by output feedback for a class of uncertain nonlinear systems with not only unmeasured states dependent growth but also time-varying time delay. Compared with the closely related works, the remarkableness of the paper is that the time-varying time delay and unmeasurable states are permitted in the system nonlinear growth. Motivated by the related tracking results and flexibly using the ideas and techniques of universal control and dead zone, an adaptive output-feedback tracking controller is explicitly designed with the help of a new Lyapunov-Krasovskii functional, to make the tracking error prescribed arbitrarily small after a finite time while keeping all the closed-loop signals bounded. A numerical example demonstrates the effectiveness of the results. PMID:25276859
Taylor, Z A; Cheng, M; Ourselin, S
2008-05-01
The use of biomechanical modelling, especially in conjunction with finite element analysis, has become common in many areas of medical image analysis and surgical simulation. Clinical employment of such techniques is hindered by conflicting requirements for high fidelity in the modelling approach, and fast solution speeds. We report the development of techniques for high-speed nonlinear finite element analysis for surgical simulation. We use a fully nonlinear total Lagrangian explicit finite element formulation which offers significant computational advantages for soft tissue simulation. However, the key contribution of the work is the presentation of a fast graphics processing unit (GPU) solution scheme for the finite element equations. To the best of our knowledge, this represents the first GPU implementation of a nonlinear finite element solver. We show that the present explicit finite element scheme is well suited to solution via highly parallel graphics hardware, and that even a midrange GPU allows significant solution speed gains (up to 16.8 x) compared with equivalent CPU implementations. For the models tested the scheme allows real-time solution of models with up to 16,000 tetrahedral elements. The use of GPUs for such purposes offers a cost-effective high-performance alternative to expensive multi-CPU machines, and may have important applications in medical image analysis and surgical simulation.
Selvendran, S.; Sivanantharaja, A.; Arivazhagan, S.; Kannan, M.
2016-09-01
We propose an index profiled, highly nonlinear ultraflattened dispersion fibre (HN-UFF) with appreciable values of fibre parameters such as dispersion, dispersion slope, effective area, nonlinearity, bending loss and splice loss. The designed fibre has normal zero flattened dispersion over S, C, L, U bands and extends up to 1.9857 μm. The maximum dispersion variation observed for this fibre is as low as 1.61 ps km-1 nm-1 over the 500-nm optical fibre transmission spectrum. This fibre also has two zero dispersion wavelengths at 1.487 and 1.9857 μm and the respective dispersion slopes are 0.02476 and 0.0068 ps nm-2 km-1. The fibre has a very low ITU-T cutoff wavelength of 1.2613 μm and a virtuous nonlinear coefficient of 9.43 W-1 km-1. The wide spectrum of zero flattened dispersion and a good nonlinear coefficient make the designed fibre very promising for different nonlinear optical signal processing applications.
Positive Almost Periodic Solution on a Nonlinear Logistic Biological Model with Grazing Rates
Institute of Scientific and Technical Information of China (English)
NI Hua; TIAN Li-xin
2013-01-01
In this paper,we study the following nonlinear biological model dx(t)/dt =x(t)[a(t)-b(t)xα(t)] + f(t,xt),by using fixed pointed theorem,the sufficient conditions of the existence of unique positive almost periodic solution for the above system are obtained,by using the theories of stability,the sufficient conditions which guarantee the stability of the positive almost periodic solution are derived.
Non-equilibrium condensation process in holographic superconductor with nonlinear electrodynamics
Liu, Yunqi; Wang, Bin
2015-01-01
We study the non-equilibrium condensation process in a holographic superconductor with nonlinear corrections to the U(1) gauge field. We start with an asymptotic Anti-de-Sitter(AdS) black hole against a complex scalar perturbation at the initial time, and solve the dynamics of the gravitational systems in the bulk. When the black hole temperature T is smaller than a critical value Tc, the scalar perturbation grows exponentially till saturation, the final state of spacetime approaches to a hairy black hole. In the bulk theory, we find the clue of the influence of nonlinear corrections in the gauge field on the process of the scalar field condensation. We show that the bulk dynamics in the non-equilibrium process is completely consistent with the observations on the boundary order parameter. Furthermore we examine the time evolution of horizons in the bulk non-equilibrium transformation process from the bald AdS black hole to the AdS hairy hole. Both the evolution of apparent and event horizons show that the or...
Vavulin, D. N.; Sukhorukov, A. A.
2016-08-01
We present an analytical description of the process of spontaneous four-wave mixing in a cubic nonlinear fiber with linear losses. We consider the generation of photon pairs in the fiber when in the input of fiber is fed the pumping wave and single signal photon. The focus of attention is on three cases: when the signal photon propagates in the fiber without generating of biphotons; when the photon pair is generated; and when the photon is lost in the fiber. We also consider the cascade processes, but do not give them an analytical description because of their smallness. Description of the biphotons generation process we provide using the Schrodinger-type equation, and take into account the losses in the fiber through the introduction of the virtual beam splitters. We demonstrate the effectiveness of the generation of photon pairs through parametric processes.
Definition of distance for nonlinear time series analysis of marked point process data
Energy Technology Data Exchange (ETDEWEB)
Iwayama, Koji, E-mail: koji@sat.t.u-tokyo.ac.jp [Research Institute for Food and Agriculture, Ryukoku Univeristy, 1-5 Yokotani, Seta Oe-cho, Otsu-Shi, Shiga 520-2194 (Japan); Hirata, Yoshito; Aihara, Kazuyuki [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)
2017-01-30
Marked point process data are time series of discrete events accompanied with some values, such as economic trades, earthquakes, and lightnings. A distance for marked point process data allows us to apply nonlinear time series analysis to such data. We propose a distance for marked point process data which can be calculated much faster than the existing distance when the number of marks is small. Furthermore, under some assumptions, the Kullback–Leibler divergences between posterior distributions for neighbors defined by this distance are small. We performed some numerical simulations showing that analysis based on the proposed distance is effective. - Highlights: • A new distance for marked point process data is proposed. • The distance can be computed fast enough for a small number of marks. • The method to optimize parameter values of the distance is also proposed. • Numerical simulations indicate that the analysis based on the distance is effective.
Subexponential loss rate asymptotics for Lévy processes
DEFF Research Database (Denmark)
Andersen, Lars Nørvang
We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean time spent at the upper barrier K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive...... asymptotics for the loss rate when K tends to infinity, when the mean of the Lévy process is negative and the positive jumps are subexponential. In the course of this derivation, we achieve a formula, which is a generalization of the celebrated Pollaczeck-Khinchine formula.......We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean time spent at the upper barrier K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive...
Subexponential loss rate asymptotics for Lévy processes
DEFF Research Database (Denmark)
Andersen, Lars Nørvang
2011-01-01
We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean of the local time at K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive asymptotic...... for the loss rate when K tends to infinity, when the mean of the Lévy process is negative and the positive jumps are subexponential. In the course of this derivation, we achieve a formula, which is a generalization of the celebrated Pollaczeck-Khinchine formula.......We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean of the local time at K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive asymptotics...
Directory of Open Access Journals (Sweden)
Meleiro L.A.C.
2000-01-01
Full Text Available Most advanced computer-aided control applications rely on good dynamics process models. The performance of the control system depends on the accuracy of the model used. Typically, such models are developed by conducting off-line identification experiments on the process. These experiments for identification often result in input-output data with small output signal-to-noise ratio, and using these data results in inaccurate model parameter estimates [1]. In this work, a multivariable adaptive self-tuning controller (STC was developed for a biotechnological process application. Due to the difficulties involving the measurements or the excessive amount of variables normally found in industrial process, it is proposed to develop "soft-sensors" which are based fundamentally on artificial neural networks (ANN. A second approach proposed was set in hybrid models, results of the association of deterministic models (which incorporates the available prior knowledge about the process being modeled with artificial neural networks. In this case, kinetic parameters - which are very hard to be accurately determined in real time industrial plants operation - were obtained using ANN predictions. These methods are especially suitable for the identification of time-varying and nonlinear models. This advanced control strategy was applied to a fermentation process to produce ethyl alcohol (ethanol in industrial scale. The reaction rate considered for substratum consumption, cells and ethanol productions are validated with industrial data for typical operating conditions. The results obtained show that the proposed procedure in this work has a great potential for application.
Intrinsic Nonlinearities and Layout Impacts of 100 V Integrated Power MOSFETs in Partial SOI Process
DEFF Research Database (Denmark)
Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger
Parasitic capacitances of power semiconductors are a part of the key design parameters of state-of-the-art very high frequency (VHF) power supplies. In this poster, four 100 V integrated power MOSFETs with different layout structures are designed, implemented, and analyzed in a 0.18 ȝm partial...... Silicon-on-Insulator (SOI) process with a die area 2.31 mm2. A small-signal model of power MOSFETs is proposed to systematically analyze the nonlinear parasitic capacitances in different transistor states: off-state, sub-threshold region, and on-state in the linear region. 3D plots are used to summarize...
Time-ordering effects in the generation of entangled photons using nonlinear optical processes.
Quesada, Nicolás; Sipe, J E
2015-03-06
We study the effects of time ordering in photon generation processes such as spontaneous parametric down-conversion (SPDC) and four wave mixing (SFWM). The results presented here are used to construct an intuitive picture that allows us to predict when time-ordering effects significantly modify the joint spectral amplitude (JSA) of the photons generated in SPDC and SFWM. These effects become important only when the photons being generated lie with the pump beam that travels through the nonlinear material for a significant amount of time. Thus sources of spectrally separable photons are ideal candidates for the observation of modifications of the JSA due to time ordering.
Imitation learning of Non-Linear Point-to-Point Robot Motions using Dirichlet Processes
DEFF Research Database (Denmark)
Krüger, Volker; Tikhanoff, Vadim; Natale, Lorenzo
2012-01-01
In this paper we discuss the use of the infinite Gaussian mixture model and Dirichlet processes for learning robot movements from demonstrations. Starting point of this work is an earlier paper where the authors learn a non-linear dynamic robot movement model from a small number of observations....... The model in that work is learned using a classical finite Gaussian mixture model (FGMM) where the Gaussian mixtures are appropriately constrained. The problem with this approach is that one needs to make a good guess for how many mixtures the FGMM should use. In this work, we generalize this approach...
Calatroni, Luca
2013-08-01
We present directional operator splitting schemes for the numerical solution of a fourth-order, nonlinear partial differential evolution equation which arises in image processing. This equation constitutes the H -1-gradient flow of the total variation and represents a prototype of higher-order equations of similar type which are popular in imaging for denoising, deblurring and inpainting problems. The efficient numerical solution of this equation is very challenging due to the stiffness of most numerical schemes. We show that the combination of directional splitting schemes with implicit time-stepping provides a stable and computationally cheap numerical realisation of the equation.
A process fault estimation strategy for non-linear dynamic systems
Pazera, Marcin; Korbicz, Józef
2017-01-01
The paper deals with the problem of simultaneous state and process fault estimation for non-linear dynamic systems. Instead of estimating the fault directly, its product with state and the state itself are estimated. To derive the fault from the product, a simple algebraic approach is proposed. The estimation strategy is based on the quadratic boundedness approach. The final part of the paper presents an illustrative example concerning a laboratory multi-tank system. The real data experiments clearly exhibit the performance of the proposed approach.
Perkins, Steven E; Jelinek, Herbert F; Al-Aubaidy, Hayder A; de Jong, Berverlie
2017-03-01
Recovery of cardiac autonomic modulation following exercise can be measured using heart rate variability. The objective of this study was to investigate and compare recovery of autonomic cardiac regulation over three days following a single session of high intensity interval training compared to endurance training. Nine untrained students completed two exercise protocols in a one-way crossover design. The endurance protocol consisted of 45min of moderate intensity cycling, and the high intensity interval protocol of six 30s sets of high intensity cycling. Cardiac autonomic activity recovery was measured over three days post-exercise for two hours immediately following each exercise session and each morning thereafter using linear and nonlinear heart rate variability analysis. Both linear and nonlinear measures were significantly decreased immediately following exercise indicating loss of vagal activity. Root mean sum of squared differences (p=0.031) and high frequency (p=0.031) were suppressed following the interval exercise only. The long term correlation of the heart rate applying detrended fluctuation analysis was decreased immediately following endurance training (p=0.039) and trended to increase immediately following the interval protocol (p=0.156). Sample entropy was decreased immediately following both the endurance (p=0.023) and interval (p=0.031) protocols. No exercise effects were noted from 24h post exercise onwards. High intensity interval training had a greater impact on neurocardiac activity than moderate intensity endurance training as indicated by both linear and nonlinear heart rate variability measures. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Estimation and filtering of nonlinear systems application to a waste-water treatment process
Energy Technology Data Exchange (ETDEWEB)
Ben Youssef, C.; Dahhou, B. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France). Lab. d`Automatique et d`Analyse des Systemes]|[Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France); Zeng, F.Y.; Rols, J.L. [Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France)
1994-04-01
A fundamental task in design and control of biotechnological processes is system modelling. This task is made difficult by the scarceness of on-line direct sensors for some key variables and by the fact that identifiability of models including Michaelis-Menten type of nonlinearities is not straightforward. The use of adaptive estimation approaches constitutes an interesting alternative to circumvent these kind of problems. This paper discusses an identification technique derived to solve the problem of estimating simultaneously inaccessible state variables and time-varying parameters of a nonlinear wastewater treatment process. An extended linearization technique using Kronecker`s calculation provides the error model of the joint observer-estimator procedure which convergence is proved via Lyapunov`s method. Sufficient conditions for stability of this joint identification scheme are given and discussed according to the persistence excitation conditions of the signals. A simulation study with measurement noises and abrupt jumps of the process parameters shows the feasibility and significant robustness of the proposed adaptive estimation methodologies. (author). (author). 10 refs., 3 figs.
A new cellular nonlinear network emulation on FPGA for EEG signal processing in epilepsy
Müller, Jens; Müller, Jan; Tetzlaff, Ronald
2011-05-01
For processing of EEG signals, we propose a new architecture for the hardware emulation of discrete-time Cellular Nonlinear Networks (DT-CNN). Our results show the importance of a high computational accuracy in EEG signal prediction that cannot be achieved with existing analogue VLSI circuits. The refined architecture of the processing elements and its resource schedule, the cellular network structure with local couplings, the FPGA-based embedded system containing the DT-CNN, and the data flow in the entire system will be discussed in detail. The proposed DT-CNN design has been implemented and tested on an Xilinx FPGA development platform. The embedded co-processor with a multi-threading kernel is utilised for control and pre-processing tasks and data exchange to the host via Ethernet. The performance of the implemented DT-CNN has been determined for a popular example and compared to that of a conventional computer.
Directory of Open Access Journals (Sweden)
J. Azaña
2012-01-01
Full Text Available We review recent work on all-fiber (long-period fiber grating devices for optical pulse shaping, particularly flat-top pulse generation, down to the subpicosecond range and their application for nonlinear switching (demultiplexing of optical time-division multiplexed (OTDM data signals in fiber-optic telecommunication links operating up to 640 Gbit/s. Experiments are presented demonstrating error-free 640-to-10 Gbit/s demultiplexing of the 64 tributary channels using the generated flat-top pulses for temporal gating in a Kerr-effect-based nonlinear optical loop mirror. The use of flat-top pulses has critical benefits in the demultiplexing process, including a significantly increased timing-jitter tolerance (up to ~500 fs, i.e., 30% of the bit period and the associated improvement in the bit-error-rate performance (e.g., with a sensitivity increase of up to ~13 dB as compared with the use of Gaussian-like gating pulses. Long-period fiber grating pulse shapers with reduced polarization dependence are fabricated and successfully used for polarization-independent 640-to-10 Gbit/s demultiplexing experiments.
Totally asymmetric exclusion processes with spatially periodic hopping rates
Lakatos, Greg; Kolomeisky, Anatoly; Chou, Tom
2004-03-01
Using mean-field and numerical methods, we analyze the steady-state behavior of totally asymmetric simple exclusion processes (TASEPs) containing periodically varying movement rates. In our models particles at a majority sites hop to the right with rate p_1, while particles occupying a periodically arranged set of sites move to the right at rate p_2. While exact solutions for the steady-state particle currents and densities are not found, the mean field results show good agreement with data derived from extensive Monte-Carlo simulations.
Rate of non-linearity in DMS aerosol-cloud-climate interactions
Directory of Open Access Journals (Sweden)
M. A. Thomas
2011-11-01
Full Text Available The degree of non-linearity in DMS-cloud-climate interactions is assessed using the ECHAM5-HAMMOZ model by taking into account end-to-end aerosol chemistry-cloud microphysics link. The evaluation is made over the Southern oceans in austral summer, a region of minimal anthropogenic influence. In this study, we compare the DMS-derived changes in the aerosol and cloud microphysical properties between a baseline simulation with the ocean DMS emissions from a prescribed climatology, and a scenario where the DMS emissions are doubled. Our results show that doubling the DMS emissions in the current climate results in a non-linear response in atmospheric DMS burden and subsequently, in SO_{2} and H_{2}SO_{4} burdens due to inadequate OH oxidation. The aerosol optical depth increases by only ~20 % in the 30° S–75° S belt in the SH summer months. This increases the vertically integrated cloud droplet number concentrations (CDNC by 25 %. Since the vertically integrated liquid water vapor is constant in our model simulations, an increase in CDNC leads to a reduction in cloud droplet radius of 3.4 % over the Southern oceans in summer. The equivalent increase in cloud liquid water path is 10.7 %. The above changes in cloud microphysical properties result in a change in global annual mean radiative forcing at the TOA of −1.4 W m^{−2}. The results suggest that the DMS-cloud microphysics link is highly non-linear. This has implications for future studies investigating the DMS-cloud climate feedbacks in a warming world and for studies evaluating geoengineering options to counteract warming by modulating low level marine clouds.
Engineering aspects of rate-related processes in food manufacturing.
Adachi, Shuji
2015-01-01
Many rate-related phenomena occur in food manufacturing processes. This review addresses four of them, all of which are topics that the author has studied in order to design food manufacturing processes that are favorable from the standpoint of food engineering. They include chromatographic separation through continuous separation with a simulated moving adsorber, lipid oxidation kinetics in emulsions and microencapsulated systems, kinetic analysis and extraction in subcritical water, and water migration in pasta.
Directory of Open Access Journals (Sweden)
T. G. Shepherd
2009-11-01
Full Text Available An analysis of the attribution of past and future changes in stratospheric ozone and temperature to anthropogenic forcings is presented. The analysis is an extension of the study of Shepherd and Jonsson (2008 who analyzed chemistry-climate simulations from the Canadian Middle Atmosphere Model (CMAM and attributed both past and future changes to changes in the external forcings, i.e. the abundances of ozone-depleting substances (ODS and well-mixed greenhouse gases. The current study is based on a new CMAM dataset and includes two important changes. First, we account for the nonlinear radiative response to changes in CO2. It is shown that over centennial time scales the radiative response in the upper stratosphere to CO2 changes is significantly nonlinear and that failure to account for this effect leads to a significant error in the attribution. To our knowledge this nonlinearity has not been considered before in attribution analysis, including multiple linear regression studies. For the regression analysis presented here the nonlinearity was taken into account by using CO2 heating rate, rather than CO2 abundance, as the explanatory variable. This approach yields considerable corrections to the results of the previous study and can be recommended to other researchers. Second, an error in the way the CO2 forcing changes are implemented in the CMAM was corrected, which significantly affects the results for the recent past. As the radiation scheme, based on Fomichev et al. (1998, is used in several other models we provide some description of the problem and how it was fixed.
Nonlinear software sensor for monitoring genetic regulation processes with noise and modeling errors
Ibarra-Junquera, V.; Torres, L. A.; Rosu, H. C.; Argüello, G.; Collado-Vides, J.
2005-07-01
Nonlinear control techniques by means of a software sensor that are commonly used in chemical engineering could be also applied to genetic regulation processes. We provide here a realistic formulation of this procedure by introducing an additive white Gaussian noise, which is usually found in experimental data. Besides, we include model errors, meaning that we assume we do not know the nonlinear regulation function of the process. In order to illustrate this procedure, we employ the Goodwin dynamics of the concentrations [B. C. Goodwin, Temporal Oscillations in Cells (Academic, New York, 1963)] in the simple form recently applied to single gene systems and some operon cases [H. De Jong, J. Comput. Biol. 9, 67 (2002)], which involves the dynamics of the mRNA, given protein and metabolite concentrations. Further, we present results for a three gene case in coregulated sets of transcription units as they occur in prokaryotes. However, instead of considering their full dynamics, we use only the data of the metabolites and a designed software sensor. We also show, more generally, that it is possible to rebuild the complete set of nonmeasured concentrations despite the uncertainties in the regulation function or, even more, in the case of not knowing the mRNA dynamics. In addition, the rebuilding of concentrations is not affected by the perturbation due to the additive white Gaussian noise and also we managed to filter the noisy output of the biological system.
Munck, Sebastian; Miskiewicz, Katarzyna; Sannerud, Ragna; Menchon, Silvia A; Jose, Liya; Heintzmann, Rainer; Verstreken, Patrik; Annaert, Wim
2012-05-01
Visualization of organelles and molecules at nanometer resolution is revolutionizing the biological sciences. However, such technology is still limited for many cell biologists. We present here a novel approach using photobleaching microscopy with non-linear processing (PiMP) for sub-diffraction imaging. Bleaching of fluorophores both within the single-molecule regime and beyond allows visualization of stochastic representations of sub-populations of fluorophores by imaging the same region over time. Our method is based on enhancing the probable positions of the fluorophores underlying the images. The random nature of the bleached fluorophores is assessed by calculating the deviation of the local actual bleached fluorescence intensity to the average bleach expectation as given by the overall decay of intensity. Subtracting measured from estimated decay images yields differential images. Non-linear enhancement of maxima in these diffraction-limited differential images approximates the positions of the underlying structure. Summing many such processed differential images yields a super-resolution PiMP image. PiMP allows multi-color, three-dimensional sub-diffraction imaging of cells and tissues using common fluorophores and can be implemented on standard wide-field or confocal systems.
ATTITUDE RATE ESTIMATION BY GPS DOPPLER SIGNAL PROCESSING
Institute of Scientific and Technical Information of China (English)
He Side; Milos Doroslovacki; Guo Zhenyu; Zhang Yufeng
2003-01-01
A method is presented for near-Earth spacecraft or aviation vehicle's attitude rate estimation by using relative Doppler frequency shift of the Global Positioning System (GPS)carrier. It comprises two GPS receiving antennas, a signal processing circuit and an algorithm.The whole system is relatively simple, the cost and wcight, as well as power consumption, are very low.
Relationship between SCR, heart rate and information processing.
Swart, de J.H.; Das-Smaal, E.A.
1976-01-01
This study was designed to investigate the relationship between the amount of information processing in concept learning (CL) and autonomic physiological activity as measured by skin conductance response (SCR). Heart rate (HR) was also measured. Two conceptual rules were used: a conjunctive and an i
DEFF Research Database (Denmark)
Kooths, Stefan; Mitze, Timo Friedel; Ringhut, Eric
2004-01-01
This paper compares the predictive power of linear econometric and non-linear computational models for forecasting the inflation rate in the European Monetary Union (EMU). Various models of both types are developed using different monetary and real activity indicators. They are compared according...... to a battery of parametric and non-parametric test statistics to measure their performance in one- and four-step ahead forecasts of quarterly data. Using genetic-neural fuzzy systems we find the computational approach superior to some degree and show how to combine both techniques successfully....
High-energy, high-rate materials processing
Marcus, H. L.; Bourell, D. L.; Eliezer, Z.; Persad, C.; Weldon, W.
1987-12-01
The increasingly available range of pulsed-power, high energy kinetic storage devices, such as low-inductance pulse-forming networks, compulsators, and homopolar generators, is presently considered as a basis for industrial high energy/high rate (HEHR) processing to accomplish shock hardening, drilling, rapid surface alloying and melting, welding and cutting, transformation hardening, and cladding and surface melting in metallic materials. Time-temperature-transformation concepts furnish the basis for a fundamental understanding of the potential advantages of this direct pulsed power processing. Attention is given to the HEHR processing of a refractory molybdenum alloy, a nickel-base metallic glass, tungsten, titanium aluminides, and metal-matrix composites.
Shi, Huaitao; Liu, Jianchang; Wu, Yuhou; Zhang, Ke; Zhang, Lixiu; Xue, Peng
2016-04-01
It is pretty significant for fault diagnosis timely and accurately to improve the dependability of industrial processes. In this study, fault diagnosis of nonlinear and large-scale processes by variable-weighted kernel Fisher discriminant analysis (KFDA) based on improved biogeography-based optimisation (IBBO) is proposed, referred to as IBBO-KFDA, where IBBO is used to determine the parameters of variable-weighted KFDA, and variable-weighted KFDA is used to solve the multi-classification overlapping problem. The main contributions of this work are four-fold to further improve the performance of KFDA for fault diagnosis. First, a nonlinear fault diagnosis approach with variable-weighted KFDA is developed for maximising separation between the overlapping fault samples. Second, kernel parameters and features selection of variable-weighted KFDA are simultaneously optimised using IBBO. Finally, a single fitness function that combines erroneous diagnosis rate with feature cost is created, a novel mixed kernel function is introduced to improve the classification capability in the feature space and diagnosis accuracy of the IBBO-KFDA, and serves as the target function in the optimisation problem. Moreover, an IBBO approach is developed to obtain the better quality of solution and faster convergence speed. On the one hand, the proposed IBBO-KFDA method is first used on Tennessee Eastman process benchmark data sets to validate the feasibility and efficiency. On the other hand, IBBO-KFDA is applied to diagnose faults of automation gauge control system. Simulation results demonstrate that IBBO-KFDA can obtain better kernel parameters and feature vectors with a lower computing cost, higher diagnosis accuracy and a better real-time capacity.
Comparison of linear and nonlinear feedback control of heart rate for treadmill running
National Research Council Canada - National Science Library
Hunt, Kenneth J; Maurer, Roman R
2016-01-01
Heart rate can be used to define exercise intensity; feedback control systems for treadmills which automatically adjust speed to track arbitrary heart rate target profiles are therefore of interest...
Li, Huanhuan; Chen, Diyi; Zhang, Hao; Wang, Feifei; Ba, Duoduo
2016-12-01
In order to study the nonlinear dynamic behaviors of a hydro-turbine governing system in the process of sudden load increase transient, we establish a novel nonlinear dynamic model of the hydro-turbine governing system which considers the elastic water-hammer model of the penstock and the second-order model of the generator. The six nonlinear dynamic transfer coefficients of the hydro-turbine are innovatively proposed by utilizing internal characteristics and analyzing the change laws of the characteristic parameters of the hydro-turbine governing system. Moreover, from the point of view of engineering, the nonlinear dynamic behaviors of the above system are exhaustively investigated based on bifurcation diagrams and time waveforms. More importantly, all of the above analyses supply theoretical basis for allowing a hydropower station to maintain a stable operation in the process of sudden load increase transient.
Institute of Scientific and Technical Information of China (English)
Zhiyun Zou; Dandan Zhao; Xinghong Liu; Yuqing Guo; Chen Guan; Wenqiang Feng; Ning Guo
2015-01-01
By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward based on the linear system pole placement self tuning control algorithm. And the nonlinear Hammerstein system pole placement self tuning control (NL-PP-STC) algorithm was presented in detail. The identification ability of its parameter estimation algorithm of NL-PP-STC was analyzed, which was always identifiable in closed loop. Two particular problems including the selection of poles and the on-line estimation of model parameters, which may be met in applications of NL-PP-STC to real process control, were discussed. The control simulation of a strong nonlinear pH neutralization process was carried out and good control performance was achieved.
Institute of Scientific and Technical Information of China (English)
陶华学; 郭金运
2003-01-01
Data coming from different sources have different types and temporal states. Relations between one type of data and another ones, or between data and unknown parameters are almost nonlinear. It is not accurate and reliable to process the data in building the digital earth with the classical least squares method or the method of the common nonlinear least squares. So a generalized nonlinear dynamic least squares method was put forward to process data in building the digital earth. A separating solution model and the iterative calculation method were used to solve the generalized nonlinear dynamic least squares problem. In fact, a complex problem can be separated and then solved by converting to two sub-problems, each of which has a single variable. Therefore the dimension of unknown parameters can be reduced to its half, which simplifies the original high dimensional equations.
Indirect rp-process Rate Measurements from Single Neutron Removal
Amthor, A. M.; Bazin, D.; Becerril, A.; Cole, A.; Cook, J.; Estrade, A.; Gade, A.; Howard, M.; Lorusso, G.; Matos, M.; Pereira, J.; Portillo, M.; Schatz, H.; Sherrill, B.; Smith, K.; Stolz, A.; Weisshaar, D.; Zegers, R. G. T.; Galaviz, D.; Chen, A.; Fulop, Zs.; Smith, E.; Wiescher, M.
2007-10-01
The structure of nuclei along the rp-process path in Type I X-ray bursts has been studied using neutron removal from radioactive beams produced at the National Superconducting Cyclotron Laboratory. Recently, ^37Ca and ^36K have been studied in this way to reduce the uncertainty in ^35Ar(p,γ)^36K and ^36K(p,γ)^37Ca reaction rates, which are important during burst rise. Under burst conditions these rates are dominated by resonant capture contributions from individual resonances because of the low level density just above the proton threshold, precluding the use of statistical methods based on level density to determine the reaction rates. Therefore, precise structure measurements are required to reduce the orders of magnitude rate uncertainty in these key reactions and thereby constrain X-ray burst models. Preliminary results will be presented along with the implications for X-ray burst models.
Institute of Scientific and Technical Information of China (English)
Kechang FU; Liankui DAI; Tiejun WU; Ming ZHU
2009-01-01
A new sensor fault diagnosis method based on structured kernel principal component analysis (KPCA) is proposed for nonlinear processes.By performing KPCA on subsets of variables,a set of structured residuals,i.e.,scaled powers of KPCA,can be obtained in the same way as partial PCA.The structured residuals are utilized in composing an isolation scheme for sensor fault diagnosis,according to a properly designed incidence matrix.Sensor fault sensitivity and critical sensitivity are defined,based on which an incidence matrix optimization algorithm is proposed to improve the performance of the structured KPCA.The effectiveness of the proposed method is demonstrated on the simulated continuous stirred tank reactor (CSTR) process.
Development of a robust calibration model for nonlinear in-line process data
Despagne; Massart; Chabot
2000-04-01
A comparative study involving a global linear method (partial least squares), a local linear method (locally weighted regression), and a nonlinear method (neural networks) has been performed in order to implement a calibration model on an industrial process. The models were designed to predict the water content in a reactor during a distillation process, using in-line measurements from a near-infrared analyzer. Curved effects due to changes in temperature and variations between the different batches make the problem particularly challenging. The influence of spectral range selection and data preprocessing has been studied. With each calibration method, specific procedures have been applied to promote model robustness. In particular, the use of a monitoring set with neural networks does not always prevent overfitting. Therefore, we developed a model selection criterion based on the determination of the median of monitoring error over replicate trials. The back-propagation neural network models selected were found to outperform the other methods on independent test data.
Nonlinear mechanisms to Rogue events in the process of interaction between optical filaments
Kovachev, L M
2015-01-01
We investigate two types of nonlinear interaction between collinear femtosecond laser pulses with power slightly above the critical for self-focusing $P_{cr}$. In the first case we study energy exchange between filaments. The model describes this process through degenerate four-photon parametric mixing (FPPM) scheme and requests initial phase difference between the waves. When there are no initial phase difference between the pulses, the FPPM process does not work. In this case it is obtained the second type of interaction as merging between two, three or four filaments in a single filament with higher power. It is found that in the second case the interflow between the filaments has potential of interaction due to cross-phase modulation (CPM).
Improved Kernel PLS-based Fault Detection Approach for Nonlinear Chemical Processes
Institute of Scientific and Technical Information of China (English)
王丽; 侍洪波
2014-01-01
In this paper, an improved nonlinear process fault detection method is proposed based on modified ker-nel partial least squares (KPLS). By integrating the statistical local approach (SLA) into the KPLS framework, two new statistics are established to monitor changes in the underlying model. The new modeling strategy can avoid the Gaussian distribution assumption of KPLS. Besides, advantage of the proposed method is that the kernel latent variables can be obtained directly through the eigen value decomposition instead of the iterative calculation, which can improve the computing speed. The new method is applied to fault detection in the simulation benchmark of the Tennessee Eastman process. The simulation results show superiority on detection sensitivity and accuracy in com-parison to KPLS monitoring.
Leydesdorff, Loet; de Nooy, Wouter
2012-01-01
The process of innovation follows non-linear patterns across the domains of science, technology, and the economy. Novel bibliometric mapping techniques can be used to investigate and represent distinctive, but complementary perspectives on the innovation process (e.g., "demand" and "supply") as well as the interactions among these perspectives. The perspectives can be represented as "continents" of data related to varying extents over time. For example, the different branches of Medical Subject Headings (MeSH) in the Medline database provide sources of such perspectives (e.g., "Diseases" versus "Drugs and Chemicals"). The multiple-perspective approach enables us to reconstruct facets of the dynamics of innovation, in terms of selection mechanisms shaping localizable trajectories and/or resulting in more globalized regimes. By expanding the data with patents and scholarly publications, we demonstrate the use of this multi-perspective approach in the case of RNA Interference (RNAi). The possibility to develop a...
Directory of Open Access Journals (Sweden)
G.S. Vorobyov
2014-04-01
Full Text Available The article describes the experimental equipment and the results of investigations of nonlinear processes occurring during the excitation of electromagnetic oscillations in the resonant electron beam devices such as an orotron-generator of diffraction radiation. These devices are finding wide application in physics and microwave technology, now. A technique for experimental research, which bases on the using of the universal electro vacuum equipment diffraction radiation analyzer and the microprocessor system for collecting and processing data. The experimental investigations results of the energy and frequency characteristics for the most common modes of the excitation oscillations in the open resonant systems such as an orotron. The implementations on the optimum modes for the oscillations excitation in such devices were recommended.
Slow and fast light using nonlinear processes in semiconductor optical amplifiers
Pesala, Bala Subrahmanyam
Ability to control the velocity of light is usually referred to as slow or fast light depending on whether the group velocity of light is reduced or increased. The slowing of light as it passes through the glass to 2/3rd its original value is a well known phenomenon. This slowing down happens due to the interaction of light with the electrons in the medium. As a general principle, stronger the interaction, larger is the reduction in velocity. Recently, a fascinating field has emerged with the objective of not only slowing down the velocity of light but also speeding it up as it goes through the medium by enhancing light-matter interaction. This unprecedented control opens up several exciting applications in various scientific disciplines ranging from nonlinear science, RF photonics to all-optical networks. Initial experiments succeeded in reducing the velocity of light more than a million times to a very impressive 17 m/s. This speed reduction is extremely useful to enhance various nonlinear processes. For RF photonic applications including phased array antennas and tunable filters, control of phase velocity of light is required while control of group velocity serves various functionalities including packet synchronization and contention resolution in an optical buffer. Within the last 10 years, several material systems have been proposed and investigated for this purpose. Schemes based on semiconductor systems for achieving slow and fast light has the advantage of extremely high speed and electrical control. In addition, they are compact, operate at room temperature and can be easily integrated with other optical subsystems. In this work, we propose to use nonlinear processes in semiconductor optical amplifiers (SOAs) for the purpose of controlling the velocity of light. The versatility of the physical processes present in SOAs enables the control of optical signals ranging from 1GHz to larger than 1000 GHz (1 THz). First, we experimentally demonstrate both
Rate of coal devolatilization in iron and steelmaking processes
Energy Technology Data Exchange (ETDEWEB)
Sampaio, R.S.; Rio Doce, C.V. do; Fruehan, R.J.; Ozturk, B. (Carnegie Mellon Univ., Pittsburgh, PA (United States). Center for Iron and Steel Making Research)
1991-01-01
The devolatilization of coal particles under ironmaking and steelmaking conditions was studied. A new experimental technique was developed to measure the rates of devolatilization. A unique method was used to prepare coal particles based on thick coal bands rich in a given maceral group. Experiments with these single particles gave good reproducibility. The rates of devolatilization for all coal types from low to high rank coals were measured in the gaseous atmosphere and within the slag phase. Real time x-ray images were taken for high volatile, low volatile and anthracite coals devolatilizing in a molten smelting slag. The rate in terms of percentage devolatilization were relatively independent of coal type and a small function of furnace temperature at high heating rates and temperatures studied. The rates depended on particle size and heating rates. The results were consistent with internal transport controlled processes primarily heat transfer. Furthermore the rates were the same in the gas and slag phase which is consistent with heat transfer control.
The Nonhomogeneous Poisson Process for Fast Radio Burst Rates
Lawrence, Earl; Vander Wiel, Scott; Law, Casey; Burke Spolaor, Sarah; Bower, Geoffrey C.
2017-09-01
This paper presents the nonhomogeneous Poisson process (NHPP) for modeling the rate of fast radio bursts (FRBs) and other infrequently observed astronomical events. The NHPP, well-known in statistics, can model the dependence of the rate on both astronomical features and the details of an observing campaign. This is particularly helpful for rare events like FRBs because the NHPP can combine information across surveys, making the most of all available information. The goal of the paper is two-fold. First, it is intended to be a tutorial on the use of the NHPP. Second, we build an NHPP model that incorporates beam patterns and a power-law flux distribution for the rate of FRBs. Using information from 12 surveys including 15 detections, we find an all-sky FRB rate of 587 events per sky per day above a flux of 1 Jy (95% CI: 272, 924) and a flux power-law index of 0.91 (95% CI: 0.57, 1.25). Our rate is lower than other published rates, but consistent with the rate given in Champion et al.
Directory of Open Access Journals (Sweden)
Li Sun
2016-01-01
Full Text Available It is assumed that the drift parameter is dependent on the acceleration variables and the diffusion coefficient remains the same across the whole accelerated degradation test (ADT in most of the literature based on Wiener process. However, the diffusion coefficient variation would also become obvious in some applications with the stress increasing. Aiming at the phenomenon, the paper concludes that both the drift parameter and the diffusion parameter depend on stress variables based on the invariance principle of failure mechanism and Nelson assumption. Accordingly, constant stress accelerated degradation process (CSADP and step stress accelerated degradation process (SSADP with random effects are modeled. The unknown parameters in the established model are estimated based on the property of degradation and degradation increment, separately for CASDT and SSADT, by the maximum likelihood estimation approach with measurement error. In addition, the simulation steps of accelerated degradation data are provided and simulated step stress accelerated degradation data is designed to validate the proposed model compared to other models. Finally, a case study of CSADT is conducted to demonstrate the benefits of our model in the practical engineering.
Preset time count rate meter using adaptive digital signal processing
Directory of Open Access Journals (Sweden)
Žigić Aleksandar D.
2005-01-01
Full Text Available Two presented methods were developed to improve classical preset time count rate meters by using adapt able signal processing tools. An optimized detection algorithm that senses the change of mean count rate was implemented in both methods. Three low-pass filters of various structures with adaptable parameters to implement the control of the mean count rate error by suppressing the fluctuations in a controllable way, were considered and one of them implemented in both methods. An adaptation algorithm for preset time interval calculation executed after the low-pass filter was devised and implemented in the first method. This adaptation algorithm makes it possible to obtain shorter preset time intervals for higher stationary mean count rate. The adaptation algorithm for preset time interval calculation executed before the low-pass filter was devised and implemented in the second method. That adaptation algorithm enables sensing of a rapid change of the mean count rate before fluctuations suppression is carried out. Some parameters were fixed to their optimum values after appropriate optimization procedure. Low-pass filters have variable number of stationary coefficients depending on the specified error and the mean count rate. They implement control of the mean count rate error by suppressing fluctuations in a controllable way. The simulated and realized methods, using the developed algorithms, guarantee that the response time shall not exceed 2 s for the mean count rate higher than 2 s-1 and that controllable mean count rate error shall be within the range of ±4% to ±10%.
Tanev, George; Saadi, Dorthe B; Hoppe, Karsten; Sorensen, Helge B D
2014-01-01
Chronic stress detection is an important factor in predicting and reducing the risk of cardiovascular disease. This work is a pilot study with a focus on developing a method for detecting short-term psychophysiological changes through heart rate variability (HRV) features. The purpose of this pilot study is to establish and to gain insight on a set of features that could be used to detect psychophysiological changes that occur during chronic stress. This study elicited four different types of arousal by images, sounds, mental tasks and rest, and classified them using linear and non-linear HRV features from electrocardiograms (ECG) acquired by the wireless wearable ePatch® recorder. The highest recognition rates were acquired for the neutral stage (90%), the acute stress stage (80%) and the baseline stage (80%) by sample entropy, detrended fluctuation analysis and normalized high frequency features. Standardizing non-linear HRV features for each subject was found to be an important factor for the improvement of the classification results.
Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers
Isaienko, Oleksandr; Robel, István
2016-03-01
Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7-20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.
Valenza, Gaetano; Citi, Luca; Scilingo, Enzo Pasquale; Barbieri, Riccardo
2014-01-01
Measures of entropy have been proved as powerful quantifiers of complex nonlinear systems, particularly when applied to stochastic series of heartbeat dynamics. Despite the remarkable achievements obtained through standard definitions of approximate and sample entropy, a time-varying definition of entropy characterizing the physiological dynamics at each moment in time is still missing. To this extent, we propose two novel measures of entropy based on the inho-mogeneous point-process theory. The RR interval series is modeled through probability density functions (pdfs) which characterize and predict the time until the next event occurs as a function of the past history. Laguerre expansions of the Wiener-Volterra autoregressive terms account for the long-term nonlinear information. As the proposed measures of entropy are instantaneously defined through such probability functions, the proposed indices are able to provide instantaneous tracking of autonomic nervous system complexity. Of note, the distance between the time-varying phase-space vectors is calculated through the Kolmogorov-Smirnov distance of two pdfs. Experimental results, obtained from the analysis of RR interval series extracted from ten healthy subjects during stand-up tasks, suggest that the proposed entropy indices provide instantaneous tracking of the heartbeat complexity, also allowing for the definition of complexity variability indices.
Energy Technology Data Exchange (ETDEWEB)
Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)
2003-05-07
A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.
Bell, Iris R; Sarter, Barbara; Standish, Leanna J; Banerji, Prasanta; Banerji, Pratip
2015-06-01
The purpose of the present paper is to (a) summarize evidence for the nanoparticle nature and biological effects of traditional homeopathically-prepared medicines at low and ultralow doses; (b) provide details of historically-based homeopathic green manufacturing materials and methods, relating them to top-down mechanical attrition and plant-based biosynthetic processes in modern nanotechnology; (c) outline the potential roles of nonlinear dose-responses and dynamical interactions with complex adaptive systems in generating endogenous amplification processes during low dose treatment. Possible mechanisms of low dose effects, for which there is evidence involving nanoparticles and/or homeopathically-manufactured medicines, include hormesis, time-dependent sensitization, and stochastic resonance. All of the proposed mechanisms depend upon endogenous nonlinear amplification processes in the recipient organism in interaction with the salient, albeit weak signal properties of the medicine. Conventional ligand-receptor mechanisms relevant to higher doses are less likely involved. Effects, especially for homeopathically-prepared nanophytomedicines, include bidirectional host state-dependent changes in function. Homeopathic clinicians report successful treatment of serious infections and cancers. Preclinical biological evidence is consistent with such claims. Controlled biological data on homeopathically-prepared medicines indicate modulation of gene expression and biological signaling pathways regulating cell cycles, immune reactions, and central nervous system function from studies on cells, animals, and human subjects. As a 200-year old system of traditional medicine used by millions of people worldwide, homeopathy offers a pulsed low dose treatment strategy and strong safety record to facilitate progress in translational nanomedicine with plants and other natural products. In turn, modern nanotechnology methods can improve homeopathic manufacturing procedures
Nonlinear modeling of activated sludge process using the Hammerstein-Wiener structure
Directory of Open Access Journals (Sweden)
Frącz Paweł
2016-01-01
Full Text Available The paper regards to physical model of the Activated Sludge Process, which is a part of the wastewater treatment. The aim of the study was to describe nitrogen transformation process and the demand of chemical fractions, involved in the ASP process. Moreover, the non-linear relationship between the flow of wastewater and the consumed electrical energy, used by the blowers, was determined. Such analyses are important from the economical and environmental point of view. Assuming that the total power does not change the blower is charging during a year an energy amount of approx. 613 MW. This illustrates in particular the scale of the demand for energy consumption in the biological aeration unit. The aim is to minimize the energy consumption through first building a model of ASP and then through optimization of the overall process by modifying chosen parameter in numerical simulations. In this paper example measurement and analysis results of nitrite and ammonium nitrogen concentrations in the aeration reactor and the active power consumed by blowers for the aeration process were presented. Further the ASP modeling procedure, which uses the Hammerstein-Wiener structure and example verification results were presented. Based on the achieved results it was stated that the developed set of methodologies may be used to improve and expand the overriding control system for system for wastewater treatment plant.
Inferring time derivatives including cell growth rates using Gaussian processes
Swain, Peter S.; Stevenson, Keiran; Leary, Allen; Montano-Gutierrez, Luis F.; Clark, Ivan B. N.; Vogel, Jackie; Pilizota, Teuta
2016-12-01
Often the time derivative of a measured variable is of as much interest as the variable itself. For a growing population of biological cells, for example, the population's growth rate is typically more important than its size. Here we introduce a non-parametric method to infer first and second time derivatives as a function of time from time-series data. Our approach is based on Gaussian processes and applies to a wide range of data. In tests, the method is at least as accurate as others, but has several advantages: it estimates errors both in the inference and in any summary statistics, such as lag times, and allows interpolation with the corresponding error estimation. As illustrations, we infer growth rates of microbial cells, the rate of assembly of an amyloid fibril and both the speed and acceleration of two separating spindle pole bodies. Our algorithm should thus be broadly applicable.
Auctioning Process Innovations when Losers' Bids Determine Royalty Rates
Fan, Cuihong; Jun, Byoung Heon; Elmar G. Wolfstetter
2009-01-01
We consider a licensing mechanism for process innovations that combines a license auction with royalty contracts to those who lose the auction. Firms’ bids are dual signals of their cost reductions: the winning bid signals the own cost reduction to rival oligopolists, whereas the losing bid influences the beliefs of the innovator who uses that information to set the royalty rate. We derive conditions for existence of a separating equilibrium, explain why a sufficiently high reserve price is e...
r-PROCESS LANTHANIDE PRODUCTION AND HEATING RATES IN KILONOVAE
Energy Technology Data Exchange (ETDEWEB)
Lippuner, Jonas; Roberts, Luke F., E-mail: jlippuner@tapir.caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, MC 350-17, 1200 E California Boulevard, Pasadena CA 91125 (United States)
2015-12-20
r-process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the ejecta, which determines the local heating rate from nuclear decays and the opacity. Kasen et al. and Tanaka and Hotokezaka pointed out that lanthanides can drastically increase the opacity in these outflows. We use the new general-purpose nuclear reaction network SkyNet to carry out a parameter study of r-process nucleosynthesis for a range of initial electron fractions Y{sub e}, initial specific entropies s, and expansion timescales τ. We find that the ejecta is lanthanide-free for Y{sub e} ≳ 0.22−0.30, depending on s and τ. The heating rate is insensitive to s and τ, but certain, larger values of Y{sub e} lead to reduced heating rates, due to individual nuclides dominating the heating. We calculate approximate light curves with a simplified gray radiative transport scheme. The light curves peak at about a day (week) in the lanthanide-free (-rich) cases. The heating rate does not change much as the ejecta becomes lanthanide-free with increasing Y{sub e}, but the light-curve peak becomes about an order of magnitude brighter because it peaks much earlier when the heating rate is larger. We also provide parametric fits for the heating rates between 0.1 and 100 days, and we provide a simple fit in Y{sub e}, s, and τ to estimate whether or not the ejecta is lanthanide-rich.
DEFF Research Database (Denmark)
Peucheret, Christophe; Da Ros, Francesco; Vukovic, Dragana;
- compatible fabrication process, degrees of freedom in dispersion engineering, and high nonlinear coecient. However, the detrimental eect of free-carrier absorption induced by two-photon absorp- tion has so far prevented them from being used for the demonstration of phase-sensitive processing. Thanks...
Clubb, Fiona J.; Mudd, Simon M.; Attal, Mikaël.; Milodowski, David T.; Grieve, Stuart W. D.
2016-10-01
Drainage density is a fundamental landscape metric describing the extent of the fluvial network. We compare the relationship between drainage density (Dd) and erosion rate (E) using the Channel-Hillslope Integrated Landscape Development (CHILD) numerical model. We find that varying the channel slope exponent (n) in detachment-limited fluvial incision models controls the relationship between Dd and E, with n > 1 resulting in increasing Dd with E if all other parameters are held constant. This result is consistent when modeling both linear and nonlinear hillslope sediment flux. We also test the relationship between Dd and E in five soil-mantled landscapes throughout the USA: Feather River, CA; San Gabriel Mountains, CA; Boulder Creek, CO; Guadalupe Mountains, NM; and Bitterroot National Forest, ID. For two of these field sites we compare Dd to cosmogenic radionuclide (CRN)-derived erosion rates, and for each site we use mean hilltop curvature as a proxy for erosion rate where CRN-derived erosion rates are not available. We find that there is a significant positive relationship between Dd, E, and hilltop curvature across every site, with the exception of the San Gabriel Mountains, CA. This relationship is consistent with an n exponent greater than 1, suggesting that at higher erosion rates, the transition between advective and diffusive processes occurs at smaller contributing areas in soil-mantled landscapes.
McArthur, Duncan; Hourahine, Ben; Papoff, Francesco
2015-11-24
We model a scheme for the coherent control of light waves and currents in metallic nanospheres which applies independently of the nonlinear multiphoton processes at the origin of waves and currents. Using exact mathematical formulae, we calculate numerically with a custom fortran code the effect of an external control field which enable us to change the radiation pattern and suppress radiative losses or to reduce absorption, enabling the particle to behave as a perfect scatterer or as a perfect absorber. Data are provided in tabular, comma delimited value format and illustrate narrow features in the response of the particles that result in high sensitivity to small variations in the local environment, including subwavelength spatial shifts.
Nonlinear Sagnac interferometer based on the four-wave mixing process.
Xin, Jun; Liu, Jinming; Jing, Jietai
2017-01-23
A new nonlinear Sagnac interferometer (NSI) is proposed by replacing the beam-splitter in the traditional Sagnac interferometer (TSI) with a four-wave mixing process. Such a NSI has better angular velocity sensitivity than the one of the TSI. The standard quantum limit can be beaten and the Heisenberg Limit can even be reached for the ideal case by the NSI. We study the effect of the losses on the angular velocity sensitivity of the NSI and find that the optimal angular velocity, where the best angular velocity sensitivity can be obtained, of the NSI may be dependent on the losses inside the interferometer. Such a NSI has its advantages compared with the TSI and may find its potential applications in quantum metrology.
Nonlinear color-image decomposition for image processing of a digital color camera
Saito, Takahiro; Aizawa, Haruya; Yamada, Daisuke; Komatsu, Takashi
2009-01-01
This paper extends the BV (Bounded Variation) - G and/or the BV-L1 variational nonlinear image-decomposition approaches, which are considered to be useful for image processing of a digital color camera, to genuine color-image decomposition approaches. For utilizing inter-channel color cross-correlations, this paper first introduces TV (Total Variation) norms of color differences and TV norms of color sums into the BV-G and/or BV-L1 energy functionals, and then derives denoising-type decomposition-algorithms with an over-complete wavelet transform, through applying the Besov-norm approximation to the variational problems. Our methods decompose a noisy color image without producing undesirable low-frequency colored artifacts in its separated BV-component, and they achieve desirable high-quality color-image decomposition, which is very robust against colored random noise.
Directory of Open Access Journals (Sweden)
Naveed Ishtiaq Chaudhary
2013-01-01
Full Text Available A novel algorithm is developed based on fractional signal processing approach for parameter estimation of input nonlinear control autoregressive (INCAR models. The design scheme consists of parameterization of INCAR systems to obtain linear-in-parameter models and to use fractional least mean square algorithm (FLMS for adaptation of unknown parameter vectors. The performance analyses of the proposed scheme are carried out with third-order Volterra least mean square (VLMS and kernel least mean square (KLMS algorithms based on convergence to the true values of INCAR systems. It is found that the proposed FLMS algorithm provides most accurate and convergent results than those of VLMS and KLMS under different scenarios and by taking the low-to-high signal-to-noise ratio.
Chaudhary, Naveed Ishtiaq; Raja, Muhammad Asif Zahoor; Khan, Junaid Ali; Aslam, Muhammad Saeed
2013-01-01
A novel algorithm is developed based on fractional signal processing approach for parameter estimation of input nonlinear control autoregressive (INCAR) models. The design scheme consists of parameterization of INCAR systems to obtain linear-in-parameter models and to use fractional least mean square algorithm (FLMS) for adaptation of unknown parameter vectors. The performance analyses of the proposed scheme are carried out with third-order Volterra least mean square (VLMS) and kernel least mean square (KLMS) algorithms based on convergence to the true values of INCAR systems. It is found that the proposed FLMS algorithm provides most accurate and convergent results than those of VLMS and KLMS under different scenarios and by taking the low-to-high signal-to-noise ratio. PMID:23853538
Rodrigo, M A; Seco, A; Ferrer, J; Penya-roja, J M; Valverde, J L
1999-01-01
In this paper, several tuning algorithms, specifically ITAE, IMC and Cohen and Coon, were applied in order to tune an activated sludge aeration PID controller. Performance results of these controllers were compared by simulation with those obtained by using a nonlinear fuzzy PID controller. In order to design this controller, a trial and error procedure was used to determine, as a function of error at current time and at a previous time, sets of parameters (including controller gain, integral time and derivative time) which achieve satisfactory response of a PID controller actuating over the aeration process. Once these sets of data were obtained, neural networks were used to obtain fuzzy membership functions and fuzzy rules of the fuzzy PID controller.
We should be using nonlinear indices when relating heart-rate dynamics to cognition and mood
National Research Council Canada - National Science Library
Young, Hayley; Benton, David
2015-01-01
Both heart rate (HR) and brain functioning involve the integrated output of a multitude of regulatory mechanisms, that are not quantified adequately by linear approximations such as means and standard deviations...
Directory of Open Access Journals (Sweden)
Luiz Augusto da Cruz Meleiro
2005-06-01
Full Text Available In this work a MIMO non-linear predictive controller was developed for an extractive alcoholic fermentation process. The internal model of the controller was represented by two MISO Functional Link Networks (FLNs, identified using simulated data generated from a deterministic mathematical model whose kinetic parameters were determined experimentally. The FLN structure presents as advantages fast training and guaranteed convergence, since the estimation of the weights is a linear optimization problem. Besides, the elimination of non-significant weights generates parsimonious models, which allows for fast execution in an MPC-based algorithm. The proposed algorithm showed good potential in identification and control of non-linear processes.Neste trabalho um controlador preditivo não linear multivariável foi desenvolvido para um processo de fermentação alcoólica extrativa. O modelo interno do controlador foi representado por duas redes do tipo Functional Link (FLN, identificadas usando dados de simulação gerados a partir de um modelo validado experimentalmente. A estrutura FLN apresenta como vantagem o treinamento rápido e convergência garantida, já que a estimação dos seus pesos é um problema de otimização linear. Além disso, a eliminação de pesos não significativos gera modelos parsimoniosos, o que permite a rápida execução em algoritmos de controle preditivo baseado em modelo. Os resultados mostram que o algoritmo proposto tem grande potencial para identificação e controle de processos não lineares.
Institute of Scientific and Technical Information of China (English)
Hasan ABBASI NOZARI; Hamed DEHGHAN BANADAKI; Mohammad MOKHTARE; Somaveh HEKMATI VAHED
2012-01-01
This study deals with the neuro-fuzzy (NF) modelling of a real industrial winding process in which the acquired NF model can be exploited to improve control performance and achieve a robust fault-tolerant system.A new simulator model is proposed for a winding process using non-linear identification based on a recurrent local linear neuro-fuzzy (RLLNF) network trained by local linear model tree (LOLIMOT),which is an incremental tree-based learning algorithm.The proposed NF models are compared with other known intelligent identifiers,namely multilayer perceptron (MLP) and radial basis function (RBF).Comparison of our proposed non-linear models and associated models obtained through the least square error (LSE) technique (the optimal modelling method for linear systems) confirms that the winding process is a non-linear system.Experimental results show the effectiveness of our proposed NF modelling approach.
A Model Predictive Algorithm for Active Control of Nonlinear Noise Processes
Directory of Open Access Journals (Sweden)
Qi-Zhi Zhang
2005-01-01
Full Text Available In this paper, an improved nonlinear Active Noise Control (ANC system is achieved by introducing an appropriate secondary source. For ANC system to be successfully implemented, the nonlinearity of the primary path and time delay of the secondary path must be overcome. A nonlinear Model Predictive Control (MPC strategy is introduced to deal with the time delay in the secondary path and the nonlinearity in the primary path of the ANC system. An overall online modeling technique is utilized for online secondary path and primary path estimation. The secondary path is estimated using an adaptive FIR filter, and the primary path is estimated using a Neural Network (NN. The two models are connected in parallel with the two paths. In this system, the mutual disturbances between the operation of the nonlinear ANC controller and modeling of the secondary can be greatly reduced. The coefficients of the adaptive FIR filter and weight vector of NN are adjusted online. Computer simulations are carried out to compare the proposed nonlinear MPC method with the nonlinear Filter-x Least Mean Square (FXLMS algorithm. The results showed that the convergence speed of the proposed nonlinear MPC algorithm is faster than that of nonlinear FXLMS algorithm. For testing the robust performance of the proposed nonlinear ANC system, the sudden changes in the secondary path and primary path of the ANC system are considered. Results indicated that the proposed nonlinear ANC system can rapidly track the sudden changes in the acoustic paths of the nonlinear ANC system, and ensure the adaptive algorithm stable when the nonlinear ANC system is time variable.
Chughtai, Mohsan Niaz; Forzati, Marco; Mårtensson, Jonas; Rafique, Danish
2012-03-26
In this paper we numerically investigate nonlinear impairments in a WDM system with mixed PM (D)QPSK and OOK channels. First we analyze the dependence of XPM and XPolM on SOP and baud rate in absence of PMD. In this case we find that the nonlinear impairments are highly dependent on relative SOP between the PM (D)QPSK and neighbouring OOK channels. The dependence on relative SOP is more pronounced in differential detection than in coherent detection. However, with increasing values of PMD this dependence decreases, and non-linear tolerance improves.
r-Process Lanthanide Production and Heating Rates in Kilonovae
Lippuner, Jonas
2015-01-01
r-Process nucleosynthesis in material ejected during neutron star mergers may lead to radioactively powered transients called kilonovae. The timescale and peak luminosity of these transients depend on the composition of the material after nuclear burning ceases, which determines the local heating rate from nuclear decays and the opacity. Kasen et al. (2013, ApJ, 774, 25) and Tanaka & Hotokezaka (2013, ApJ, 775, 113) pointed out that lanthanides can drastically increase the opacity in these outflows. We use the new general-purpose nuclear reaction network SkyNet to carry out a parameter study of r-process nucleosynthesis for a range of initial electron fractions $Y_e$, initial specific entropies $s$, and expansion timescales $\\tau$. We find that the ejecta is lanthanide-free for $Y_e \\gtrsim 0.22 - 0.30$, depending on $s$ and $\\tau$. The heating rate is insensitive to $s$ and $\\tau$, but certain, larger values of $Y_e$ lead to reduced heating rates, due to individual nuclides dominating the heating. With a...
Aires, Filipe; Rossow, William B.; Hansen, James E. (Technical Monitor)
2001-01-01
A new approach is presented for the analysis of feedback processes in a nonlinear dynamical system by observing its variations. The new methodology consists of statistical estimates of the sensitivities between all pairs of variables in the system based on a neural network modeling of the dynamical system. The model can then be used to estimate the instantaneous, multivariate and nonlinear sensitivities, which are shown to be essential for the analysis of the feedbacks processes involved in the dynamical system. The method is described and tested on synthetic data from the low-order Lorenz circulation model where the correct sensitivities can be evaluated analytically.
Predicting online ratings based on the opinion spreading process
He, Xing-Sheng; Zhou, Ming-Yang; Zhuo, Zhao; Fu, Zhong-Qian; Liu, Jian-Guo
2015-10-01
Predicting users' online ratings is always a challenge issue and has drawn lots of attention. In this paper, we present a rating prediction method by combining the user opinion spreading process with the collaborative filtering algorithm, where user similarity is defined by measuring the amount of opinion a user transfers to another based on the primitive user-item rating matrix. The proposed method could produce a more precise rating prediction for each unrated user-item pair. In addition, we introduce a tunable parameter λ to regulate the preferential diffusion relevant to the degree of both opinion sender and receiver. The numerical results for Movielens and Netflix data sets show that this algorithm has a better accuracy than the standard user-based collaborative filtering algorithm using Cosine and Pearson correlation without increasing computational complexity. By tuning λ, our method could further boost the prediction accuracy when using Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE) as measurements. In the optimal cases, on Movielens and Netflix data sets, the corresponding algorithmic accuracy (MAE and RMSE) are improved 11.26% and 8.84%, 13.49% and 10.52% compared to the item average method, respectively.
de la Cruz, Rolando; Fuentes, Claudio; Meza, Cristian; Núñez-Antón, Vicente
2016-07-08
Consider longitudinal observations across different subjects such that the underlying distribution is determined by a non-linear mixed-effects model. In this context, we look at the misclassification error rate for allocating future subjects using cross-validation, bootstrap algorithms (parametric bootstrap, leave-one-out, .632 and [Formula: see text]), and bootstrap cross-validation (which combines the first two approaches), and conduct a numerical study to compare the performance of the different methods. The simulation and comparisons in this study are motivated by real observations from a pregnancy study in which one of the main objectives is to predict normal versus abnormal pregnancy outcomes based on information gathered at early stages. Since in this type of studies it is not uncommon to have insufficient data to simultaneously solve the classification problem and estimate the misclassification error rate, we put special attention to situations when only a small sample size is available. We discuss how the misclassification error rate estimates may be affected by the sample size in terms of variability and bias, and examine conditions under which the misclassification error rate estimates perform reasonably well.
Schwinger-Dyson equations in large-N quantum field theories and nonlinear random processes
Buividovich, P V
2010-01-01
We study stochastic methods for solving Schwinger-Dyson equations in large-N quantum field theories. Expectation values of single-trace operators are sampled by stationary probability distributions of so-called nonlinear random processes. The set of all histories of such processes corresponds to the set of all planar diagrams in the perturbative expansion of the theory. We describe stochastic algorithms for summation of planar diagrams in matrix-valued scalar field theory and in the Weingarten model of random planar surfaces on the lattice. For compact field variables, the method does not converge in the physically most interesting weak-coupling limit. In this case one can absorb the divergences into the self-consistent redefinition of expansion parameters. Stochastic solution of the self-consistency conditions can be implemented as a random process with memory. We illustrate this idea on the example of two-dimensional O(N) sigma-model. Extension to non-Abelian lattice gauge theories is discussed.
Influence of the dose rate in the PVDF degradation processes
Energy Technology Data Exchange (ETDEWEB)
Batista, Adriana S.M.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Gual, Maritza R., E-mail: maritzargual@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InsTEC), Departamento de Ingenieria Nuclear, La Habana (Cuba); Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)
2015-07-01
Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)
Buchner, Teodor; Petelczyc, Monika; Zebrowski, Jan J; Prejbisz, Aleksander; Kabat, Marek; Januszewicz, Andrzej; Piotrowska, Anna Justyna; Szelenberger, Waldemar
2009-06-01
Human heart rate is moderated by the autonomous nervous system acting predominantly through the sinus node (the main cardiac physiological pacemaker). One of the dominant factors that determine the heart rate in physiological conditions is its coupling with the respiratory rhythm. Using the language of stochastic processes, we analyzed both rhythms simultaneously taking the data from polysomnographic recordings of two healthy individuals. Each rhythm was treated as a sum of a deterministic drift term and a diffusion term (Kramers-Moyal expansion). We found that normal heart rate variability may be considered as the result of a bidirectional coupling of two nonlinear oscillators: the heart itself and the respiratory system. On average, the diffusion (noise) component measured is comparable in magnitude to the oscillatory (deterministic) term for both signals investigated. The application of the Kramers-Moyal expansion may be useful for medical diagnostics providing information on the relation between respiration and heart rate variability. This interaction is mediated by the autonomous nervous system, including the baroreflex, and results in a commonly observed phenomenon--respiratory sinus arrhythmia which is typical for normal subjects and often impaired by pathology.
On the nature of heart rate variability in a breathing normal subject: A stochastic process analysis
Buchner, Teodor; Petelczyc, Monika; Żebrowski, Jan J.; Prejbisz, Aleksander; Kabat, Marek; Januszewicz, Andrzej; Piotrowska, Anna Justyna; Szelenberger, Waldemar
2009-06-01
Human heart rate is moderated by the autonomous nervous system acting predominantly through the sinus node (the main cardiac physiological pacemaker). One of the dominant factors that determine the heart rate in physiological conditions is its coupling with the respiratory rhythm. Using the language of stochastic processes, we analyzed both rhythms simultaneously taking the data from polysomnographic recordings of two healthy individuals. Each rhythm was treated as a sum of a deterministic drift term and a diffusion term (Kramers-Moyal expansion). We found that normal heart rate variability may be considered as the result of a bidirectional coupling of two nonlinear oscillators: the heart itself and the respiratory system. On average, the diffusion (noise) component measured is comparable in magnitude to the oscillatory (deterministic) term for both signals investigated. The application of the Kramers-Moyal expansion may be useful for medical diagnostics providing information on the relation between respiration and heart rate variability. This interaction is mediated by the autonomous nervous system, including the baroreflex, and results in a commonly observed phenomenon—respiratory sinus arrhythmia which is typical for normal subjects and often impaired by pathology.
Yang, Huan; Liu, Yi; Zhuang, Chenggang; Shi, Junren; Yao, Yugui; Massidda, Sandro; Monni, Marco; Jia, Ying; Xi, Xiaoxing; Li, Qi; Liu, Zi-Kui; Feng, Qingrong; Wen, Hai-Hu
2008-08-01
We have measured the normal state temperature dependence of the Hall effect and magnetoresistance in epitaxial MgB2 thin films with variable disorders characterized by the residual resistance ratio RRR ranging from 4.0 to 33.3. A strong nonlinearity of the Hall effect and magnetoresistance have been found in clean samples, and they decrease gradually with the increase of disorders or temperature. By fitting the data to the theoretical model based on the Boltzmann equation and ab initio calculations for a four-band system, for the first time, we derived the scattering rates of these four bands at different temperatures and magnitude of disorders. Our method provides a unique way to derive these important parameters in multiband systems.
Energy Technology Data Exchange (ETDEWEB)
Oudalova, A.A.; Geras' kin, S.A.; Dikarev, V.G.; Nesterov, Y.B.; Dikareva, N.S
2002-07-01
The low dose region was evaluated for meristem cells of spring barley. A study of the cytogenetic damage in the low dose range was carried out to determine the genuine shape of the dose curve. The relationship between the frequency of aberrant cells and the absorbed dose is shown to be non-linear with a site at low doses within which the cytogenetic damage exceeds the control level significantly and does not depend on dose value. Within the tested exposure region, the aberrant cell frequency is found to decrease with increasing dose rate, but the shape of the dose curve remained invariable. The piecewise linear model fits the experimental data much better than the linear one. (author)
Rates of reaction and process design data for the Hydrocarb Process
Energy Technology Data Exchange (ETDEWEB)
Steinberg, M.; Kobayashi, Atsushi [Brookhaven National Lab., Upton, NY (United States); Tung, Yuanki [Hydrocarb Corp., New York, NY (United States)
1992-08-01
In support of studies for developing the coprocessing of fossil fuels with biomass by the Hydrocarb Process, experimental and process design data are reported. The experimental work includes the hydropryolysis of biomass and the thermal decomposition of methane in a tubular reactor. The rates of reaction and conversion were obtained at temperature and pressure conditions pertaining to a Hydrocarb Process design. A Process Simulation Computer Model was used to design the process and obtain complete energy and mass balances. Multiple feedstocks including biomass with natural gas and biomass with coal were evaluated. Additional feedstocks including green waste, sewage sludge and digester gas were also evaluated for a pilot plant unit.
Biodegradation Rates Assessment For An In Situ Bioremediation Process
Troquet, J.; Poutier, F.
Bioremediation methods seem a promising way of dealing with soil and subsoil con- tamination by organic substances. The biodegradation process is supported by micro- organisms which use the organic carbon from the pollutants as energy source and cells building blocks. However, bioremediation is not yet universally understood and its success is still an intensively debated issue because all soils and groundwater are not able to sustain biological growth and, then, cannot be successfully bioremediated. The outcome of each degradation process depends on several factors, which, such as oxygen transfer and pollutant bio-availability, can be controlled and are therefore key variables of such bioremediation processes. Then, it is essential to carry out a fea- sibility study based on pilot-testing before starting a remediation project in order to determine the best formulation of nutrients and bacteria to use for the specific condi- tions encountered. The scope of this work is to study the main parameters of the process and its physi- cal limiting steps in order to determine the biodegradation rates in a specific case of contamination. Several ground samples from an actual petroleum hydrocarbon con- taminated site have been laboratory tested. Five fixed bed column reactors, enabling the study of the influence of the different op- erating variables on the biodegradation kinetics, are used. The stoichiometric equation for bacteria growth and pollutant degradation has been established, allowing the de- termination of mass balances. Biodegradation monitoring is achieved by continuously measuring the emissions of carbon dioxide production and intermittently by analysing residual hydrocarbons. Results lead to the knowledge of biodegradation rates which allow to determine the treatment duration and cost.
Hybrid colored noise process with space-dependent switching rates
Bressloff, Paul C.; Lawley, Sean D.
2017-07-01
A fundamental issue in the theory of continuous stochastic process is the interpretation of multiplicative white noise, which is often referred to as the Itô-Stratonovich dilemma. From a physical perspective, this reflects the need to introduce additional constraints in order to specify the nature of the noise, whereas from a mathematical perspective it reflects an ambiguity in the formulation of stochastic differential equations (SDEs). Recently, we have identified a mechanism for obtaining an Itô SDE based on a form of temporal disorder. Motivated by switching processes in molecular biology, we considered a Brownian particle that randomly switches between two distinct conformational states with different diffusivities. In each state, the particle undergoes normal diffusion (additive noise) so there is no ambiguity in the interpretation of the noise. However, if the switching rates depend on position, then in the fast switching limit one obtains Brownian motion with a space-dependent diffusivity of the Itô form. In this paper, we extend our theory to include colored additive noise. We show that the nature of the effective multiplicative noise process obtained by taking both the white-noise limit (κ →0 ) and fast switching limit (ɛ →0 ) depends on the order the two limits are taken. If the white-noise limit is taken first, then we obtain Itô, and if the fast switching limit is taken first, then we obtain Stratonovich. Moreover, the form of the effective diffusion coefficient differs in the two cases. The latter result holds even in the case of space-independent transition rates, where one obtains additive noise processes with different diffusion coefficients. Finally, we show that yet another form of multiplicative noise is obtained in the simultaneous limit ɛ ,κ →0 with ɛ /κ2 fixed.
Process Measurement Deviation Analysis for Flow Rate due to Miscalibration
Energy Technology Data Exchange (ETDEWEB)
Oh, Eunsuk; Kim, Byung Rae; Jeong, Seog Hwan; Choi, Ji Hye; Shin, Yong Chul; Yun, Jae Hee [KEPCO Engineering and Construction Co., Deajeon (Korea, Republic of)
2016-10-15
An analysis was initiated to identify the root cause, and the exemption of high static line pressure correction to differential pressure (DP) transmitters was one of the major deviation factors. Also the miscalibrated DP transmitter range was identified as another major deviation factor. This paper presents considerations to be incorporated in the process flow measurement instrumentation calibration and the analysis results identified that the DP flow transmitter electrical output decreased by 3%. Thereafter, flow rate indication decreased by 1.9% resulting from the high static line pressure correction exemption and measurement range miscalibration. After re-calibration, the flow rate indication increased by 1.9%, which is consistent with the analysis result. This paper presents the brief calibration procedures for Rosemount DP flow transmitter, and analyzes possible three cases of measurement deviation including error and cause. Generally, the DP transmitter is required to be calibrated with precise process input range according to the calibration procedure provided for specific DP transmitter. Especially, in case of the DP transmitter installed in high static line pressure, it is important to correct the high static line pressure effect to avoid the inherent systematic error for Rosemount DP transmitter. Otherwise, failure to notice the correction may lead to indicating deviation from actual value.
Extreme-Point Symmetric Mode Decomposition Method for Nonlinear and Non-Stationary Signal Processing
Wang, Jin-Liang
2013-01-01
To process nonlinear and non-stationary signals, an extreme-point symmetric mode decomposition (ESMD) method is developed. It can be seen as a new alternate of the well-known Hilbert-Huang transform (HHT) method which is widely used nowadays. There are two parts for it. The first part is the decomposition approach which yields a series of intrinsic mode functions (IMFs) together with an optimal adaptive global mean (AGM) curve, the second part is the direct interpolating (DI) approach which yields instantaneous amplitudes and frequencies for the IMFs together with a time-varying energy. Relative to the HHT method it has five characteristics as follows: (1) Different from constructing 2 outer envelopes, its sifting process is implemented by the aid of 1, 2 or 3 inner interpolating curves; (2) It does not decompose the signal to the last trend curve with at most one extreme point, it optimizes the residual component to be an optimal AGM curve which possesses a certain number of extreme points; (3) Its symmetry ...
Fundamental nonlinearities of the reactor-settler interaction in the activated sludge process.
Diehl, Stefan; Farås, Sebastian
2012-01-01
The activated sludge process can be modelled by ordinary and partial differential equations for the biological reactors and secondary settlers, respectively. Because of the complexity of such a system, simulation models are most often used to investigate them. However, simulation models cannot give general rules on how to control a complex nonlinear process. For a reduced-order model with only two components, soluble substrate and particulate biomass, general results on steady-state solutions have recently been obtained, such as existence, uniqueness and stability of solutions. The aim of the present paper is to utilize those results to formulate some implications of practical importance. In particular, strategies are described for the manual control of the effluent substrate concentration subject to the constraint that the settler is maintained in normal operation (with a sludge blanket in the thickening zone) in steady state. Such strategies contain how the two control parameters, the recycle and waste volumetric flow ratios, should be chosen for any (steady-state) values of the input variables.
Sadeghi, Saman; Thompson, Michael
2010-01-01
It is evident that complex animate materials, which operate far from equilibrium, exhibit sensory responses to the environment through emergent patterns. Formation of such patterns is often the underlying mechanism of an active response to environmental changes and can be interpreted as a result of the distributed parallel information processing taking place within the material. Such emergent patterns are not limited to biological entities; indeed there is a wide range of complex nonlinear dissipative systems which exhibit interesting emergent patterns within a range of parameters. As one example, the present paper describes the detection of emergent phenomena associated with surface electrochemical processes that allow the system to respond to input information through evolving patterns in space and time. Associative mapping of this sort offers the opportunity to devise an electrochemical cognitive system (ECS), where pattern formation can be looked at as a macroscopic phenomenon resulting from the extensive distributive computing that occurs at the microscopic level. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.
Steward, David R.
2016-11-01
Recharge from surface to groundwater is an important component of the hydrological cycle, yet its rate is difficult to quantify. Percolation through two-dimensional circular inhomogeneities in the vadose zone is studied where one soil type is embedded within a uniform background, and nonlinear interface conditions in the quasilinear formulation are solved using Newton's method with the Analytic Element Method. This numerical laboratory identifies detectable variations in pathline and pressure head distributions that manifest due to a shift in recharge rate through in a heterogeneous media. Pathlines either diverge about or converge through coarser and finer grained materials with inverse patterns forming across lower and upper elevations; however, pathline geometry is not significantly altered by recharge. Analysis of pressure head in lower regions near groundwater identifies a new phenomenon: its distribution is not significantly impacted by an inhomogeneity soil type, nor by its placement nor by recharge rate. Another revelation is that pressure head for coarser grained inhomogeneities in upper regions is completely controlled by geometry and conductivity contrasts; a shift in recharge generates a difference Δp that becomes an additive constant with the same value throughout this region. In contrast, shifts in recharge for finer grained inhomogeneities reveal patterns with abrupt variations across their interfaces. Consequently, measurements aimed at detecting shifts in recharge in a heterogeneous vadose zone by deciphering the corresponding patterns of change in pressure head should focus on finer grained inclusions well above a groundwater table.
1976-10-29
clipping level. The nonlinear processing method described in this report provides at least 10 dB of S/N improvement over the performance obtained without...0001s Ii 0110 151 to-, ,n o 151. 1 iK) Il O( M I ( lf clipper performance was also eviden -t in the January 1974 data. Table 7 contains statisti- cal
Brando, Victoria; Castro-Zaballa, Santiago; Falconi, Atilio; Torterolo, Pablo; Migliaro, Eduardo R
2014-03-01
As a first step in a program designed to study the central control of the heart rate variability (HRV) during sleep, we conducted polysomnographic and electrocardiogram recordings on chronically-prepared cats during semi- restricted conditions. We found that the tachogram, i.e. the pattern of heart beat intervals (RR intervals) was deeply modified on passing from alert wakefulness through quiet wakefulness (QW) to sleep. While the tachogram showed a rhythmical pattern coupled with respiratory activity during non-REM sleep (NREM), it turned chaotic during REM sleep. Statistical analyses of the RR intervals showed that the mean duration increased during sleep. HRV measured by the standard deviation of normal RR intervals (SDNN) and by the square root of the mean squared difference of successive intervals (rMSSD) were larger during REM and NREM sleep than during QW. SD-1 (a marker of short- term variability) and SD-2 (a marker of long-term variability) measured by means of Poincaré plots increased during both REM and NREM sleep compared to QW. Furthermore, in the spectral analysis of RR intervals, the band of high frequency (HF) was larger in NREM and REM sleep in comparison to QW, whereas the band of low frequency (LF) was larger only during REM sleep in comparison to QW. The LF/HF ratio was larger during QW compared either with REM or NREM sleep. Finally, sample entropy analysis used as a measure of complexity, was higher during NREM in comparison to REM sleep. In conclusion, HRV parameters, including complexity, are deeply modified across behavioral states.
Frazier, D. O.; Penn, B. G.; Witherow, W. K.; Paley, M. S.
1991-01-01
Research on the growth of second- and third-order nonlinear optical (NLO) organic thin film by vapor deposition is reviewed. Particular attention is given to the experimental methods for growing thin films of p-chlorophenylurea, diacetylenes, and phthalocyanines; characteristics of the resulting films; and approaches for advancing thin film technology. It is concluded that the growth of NLO thin films by vapor processes is a promising method for the fabrication of planar waveguides for nonlinear optical devices. Two innovative approaches are proposed including a method of controlling the input beam frequency to maximize nonlinear effects in thin films and single crystals, and the alternate approach to the molecular design of organic NLO materials by increasing the transition dipole moment between ground and excited states of the molecule.
Programmable rate modem utilizing digital signal processing techniques
Bunya, George K.; Wallace, Robert L.
1989-01-01
The engineering development study to follow was written to address the need for a Programmable Rate Digital Satellite Modem capable of supporting both burst and continuous transmission modes with either binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) modulation. The preferred implementation technique is an all digital one which utilizes as much digital signal processing (DSP) as possible. Here design tradeoffs in each portion of the modulator and demodulator subsystem are outlined, and viable circuit approaches which are easily repeatable, have low implementation losses and have low production costs are identified. The research involved for this study was divided into nine technical papers, each addressing a significant region of concern in a variable rate modem design. Trivial portions and basic support logic designs surrounding the nine major modem blocks were omitted. In brief, the nine topic areas were: (1) Transmit Data Filtering; (2) Transmit Clock Generation; (3) Carrier Synthesizer; (4) Receive AGC; (5) Receive Data Filtering; (6) RF Oscillator Phase Noise; (7) Receive Carrier Selectivity; (8) Carrier Recovery; and (9) Timing Recovery.
Park, H.; Ho, C. H.; Jeong, S. J.
2015-12-01
Understanding the changes in vegetation annual cycle is crucial for improving our knowledge about various interactions between the terrestrial ecosystem and climate. However, our understanding about the vegetation seasonality is mostly confined to some phenological timings such as spring emergence and fall senescence. This study assessed large-scale variations in the vegetation green-up rate (VGrate), which indicates the rate of canopy development from winter dormancy to summer maturity, and its relationship over Northern Hemisphere temperate and boreal forests for 1982-2011. VGrate and local temperature changes show a positive correlation over the region of interest, and it indicates that a temperature increase during green-up period leads to faster canopy development. The responses of VGrate tend to be more sensitive to positive temperature anomalies than negative anomalies despite same magnitude of the temperature changes. These nonlinear responsiveness of VGrate to local temperature change is clearly observed in deciduous broadleaf forests over Eurasia compared to woodlands over North America. These results suggest that anomalous warming in green-up period would make canopy developments faster over wide temperate and boreal forest areas.
Directory of Open Access Journals (Sweden)
Zhen Chen
2016-01-01
Full Text Available Accelerated degradation test (ADT has been widely used to assess highly reliable products’ lifetime. To conduct an ADT, an appropriate degradation model and test plan should be determined in advance. Although many historical studies have proposed quite a few models, there is still room for improvement. Hence we propose a Nonlinear Generalized Wiener Process (NGWP model with consideration of the effects of stress level, product-to-product variability, and measurement errors for a higher estimation accuracy and a wider range of use. Then under the constraints of sample size, test duration, and test cost, the plans of constant-stress ADT (CSADT with multiple stress levels based on the NGWP are designed by minimizing the asymptotic variance of the reliability estimation of the products under normal operation conditions. An optimization algorithm is developed to determine the optimal stress levels, the number of units allocated to each level, inspection frequency, and measurement times simultaneously. In addition, a comparison based on degradation data of LEDs is made to show better goodness-of-fit of the NGWP than that of other models. Finally, optimal two-level and three-level CSADT plans under various constraints and a detailed sensitivity analysis are demonstrated through examples in this paper.
New Space Weather and Nonlinear Waves and Processes Prize announced for 2013
Thompson, Victoria
2012-01-01
At the 2011 Fall Meeting in San Francisco, Calif., AGU announced the creation of a new award: the Space Weather and Nonlinear Waves and Processes Prize. The prize, which is being made possible by a generous contribution from longtime AGU members and NASA Jet Propulsion Laboratory (JPL), California Institute of Technology, scientists Bruce Tsurutani and Olga Verkhoglyadova, will recognize an AGU member scientist and will come with a $10,000 award. Tsurutani has served as a researcher with JPL since 1972 and is currently a senior research scientist. He was also the president of AGU's Space Physics and Aeronomy section from 1990 to 1992 and is a recipient of AGU's John Adam Fleming Medal, given “for original research and technical leadership in geomagnetism, atmospheric electricity, aeronomy, space physics, and related sciences.” Verkhoglyadova served as a professor of space physics in the Department of Astrophysics and Space Physics at Taras Shevchenko National University of Kyiv, in the Ukraine, prior to coming to the United States. Their leadership and dedication to AGU and to their field are apparent in their passion for this prize.
Three novel high-resolution nonlinear methods for fast signal processing
Belkić, Dž.; Dando, P. A.; Main, J.; Taylor, H. S.
2000-10-01
Three novel nonlinear parameter estimators are devised and implemented for accurate and fast processing of experimentally measured or theoretically generated time signals of arbitrary length. The new techniques can also be used as powerful tools for diagonalization of large matrices that are customarily encountered in quantum chemistry and elsewhere. The key to the success and the common denominator of the proposed methods is a considerably reduced dimensionality of the original data matrix. This is achieved in a preprocessing stage called beamspace windowing or band-limited decimation. The methods are decimated signal diagonalization (DSD), decimated linear predictor (DLP), and decimated Padé approximant (DPA). Their mutual equivalence is shown for the signals that are modeled by a linear combination of time-dependent damped exponentials with stationary amplitudes. The ability to obtain all the peak parameters first and construct the required spectra afterwards enables the present methods to phase correct the absorption mode. Additionally, a new noise reduction technique, based upon the stabilization method from resonance scattering theory, is proposed. The results obtained using both synthesized and experimental time signals show that DSD/DLP/DPA exhibit an enhanced resolution power relative to the standard fast Fourier transform. Of the three methods, DPA is found to be the most efficient computationally.
Energy conversion in isothermal nonlinear irreversible processes - struggling for higher efficiency
Ebeling, W.; Feistel, R.
2017-06-01
First we discuss some early work of Ulrike Feudel on structure formation in nonlinear reactions including ions and the efficiency of the conversion of chemical into electrical energy. Then we give some survey about isothermal energy conversion from chemical to higher forms of energy like mechanical, electrical and ecological energy. Isothermal means here that there are no temperature gradients within the model systems. We consider examples of energy conversion in several natural processes and in some devices like fuel cells. Further, as an example, we study analytically the dynamics and efficiency of a simple "active circuit" converting chemical into electrical energy and driving currents which is roughly modeling fuel cells. Finally we investigate an analogous ecological system of Lotka-Volterra type consisting of an "active species" consuming some passive "chemical food". We show analytically for both these models that the efficiency increases with the load, reaches values higher then 50 percent in a narrow regime of optimal load and goes beyond some maximal load abruptly to zero.
Does the cerebral cortex exploit high dimensional, non-linear dynamics for information processing?
Directory of Open Access Journals (Sweden)
Wolf Singer
2016-09-01
Full Text Available The discovery of stimulus induced synchronisation in the visual cortex suggested the possibility that the relations among low-level stimulus features are encoded by the temporal relationship between neuronal discharges. In this framework, temporal coherence is considered a signature of perceptual grouping. This insight triggered a large number of experimental studies which sought to investigate the relationship between temporal coordination and cognitive functions. While some core predictions derived from the initial hypothesis were confirmed, these studies, also revealed a rich dynamical landscape beyond simple coherence whose role in signal processing is still poorly understood. In this paper a framework is presented which establishes links between the various manifestations of cortical dynamics by assigning specific coding functions to low dimensional dynamic features such as synchronized oscillations and phase shifts on the one hand and high dimensional non-linear, non-stationary dynamics on the other. The data serving as basis for this synthetic approach have been obtained with chronic multisite recordings from the visual cortex of anesthetized cats and from monkeys trained to solve cognitive tasks. It is proposed that the low dimensional dynamics characterized by synchronized oscillations and large-scale correlations are sub-states that represent the results of computations performed in the high dimensional state space provided by recurrently coupled networks.
2015-09-17
processing - optical frequency conversion and optical DSB -to-SSB conversion 5a. CONTRACT NUMBER FA2386-14-1-0006 5b. GRANT NUMBER Grant 134113...nonlinear dynamics of semiconductor lasers for certain optical signal processing functionalities, including optical DSB -to-SSB conversion, photonic...conversion and optical DSB -to-SSB conversion Performance Period May 30, 2014 ~ May 29, 2015 Principal Investigator Name: Sheng-Kwang Hwang Position
Liang, Heng; Jia, Zhenbin
2007-11-01
In the optimal design and control of preparative chromatographic processes, the obstacles appear when one tries to link the Wilson' s framework of chromatographic theories based on partial differential equations (PDEs) with the Eulerian presentation to optimal control approaches based on discrete time states, such as Markov decision processes (MDP) or Model predictive control (MPC). In this paper, the 0-1 model is presented to overcome the obstacles for nonlinear transport chromatography (NTC). With the Lagrangian-Eulerian description (L-ED), one solute cell unit is split into two solute cells, one (SCm) in the mobile phase with the linear velocity of the mobile phase, and the other (SCs) in the stationary phase with zero-velocity. The thermodynamic state vector, S(k), which comprises four vector components, i.e., the sequence number, the position and the local solute concentrations in both SCms and SCses, is introduced to describe the local thermodynamic path (LTP) and the macroscopical thermodynamic path (MTP). For the NTC, the LTP is designed for a solute zone to evolve from the state, S(k), to the virtual migration state, S(M), undergoing the virtual net migration sub-process, and then to the state, S(k+1), undergoing the virtual net inter phase mass transfer sub-process in a short time interval. Complete thermodynamic state iterations with the Markov characteristics are derived by using the local equilibrium isotherm and the local lumped mass transfer coefficient. When the local thermodynamic equilibrium is retained, excellent properties, such as consistency, stability, conservation, accuracy, etc., of the numerical solution of the 0-1 model are observed in the theoretical analysis and in the numerical experiments of the nonlinear ideal chromatography. It is found that the 0-1 model could properly link up with the MDP or optimal control approaches based on discrete time states.
The Expansion of Dynamic Solving Process About a Class of Non-linear Programming Problems
Institute of Scientific and Technical Information of China (English)
ZANG Zhen-chun
2001-01-01
In this paper, we research non-linear programming problems which have a given specialstructure, some simple forms of this kind structure have been solved in some papers, here we focus on othercomplex ones.
Haroon, Muhammad; Adams, Douglas E.
2007-04-01
Fatigue tests on a stabilizer bar link of an automotive suspension system are used to initiate a crack and grow the crack size. During these tests, slow sine sweeps are used to extract narrowband restoring forces across the stabilizer bar link. The restoring forces are shown to characterize the nonlinear changes in component internal forces due to crack growth. Broadband frequency response domain techniques are used to analyze the durability response data. Nonlinear frequency domain models of the dynamic transmissibility across the cracked region are shown to change as a function of crack growth. Higher order spectra are used to show the increase in nonlinear coupling of response frequency components with the appearance and growth of the crack. It is shown that crack growth can be detected and characterized by the changes in nonlinear indicators.
Uncovering Molecular Relaxation Processes with Nonlinear Spectroscopies in the Deep UV
West, Brantley Andrew
Conical intersections mediate internal conversion dynamics that compete with even the fastest nuclear motions in molecular systems. Traditional kinetic models do not apply in this regime of commensurate electronic and nuclear motion because the surroundings do not maintain equilibrium throughout the relaxation process. This dissertation focuses on uncovering the physics associated with vibronic interactions at conical intersections. Of particular interest are coherent nuclear motions driven by steep excited state potential energy gradients. Technical advances have only recently made these dynamics accessible in many systems including DNA nucleobases and cyclic polyene molecules. Optical analogues of multidimensional NMR spectroscopies have recently yielded transformative insight in relaxation processes ranging from energy transfer in photosynthesis to bond making and breaking in liquids. Prior to the start of this research, such experiments had only been conducted at infrared and visible wavelengths. Applications in the ultraviolet were motivated by studies of numerous biological systems (e.g., DNA, proteins), but had been challenged by technical issues. The work presented in this dissertation combines pulse generation techniques developed in the optical physics community with spectroscopic techniques largely pioneered by physical chemists to implement two-dimensional ultraviolet spectroscopy (2DUV). This technique is applied at the shortest wavelengths and with the best signal-to-noise ratios reported to date. Sub-picosecond excited state deactivation processes provide photo stability to the DNA double helix. Vibrational energy transfer from the solute to surrounding solvent enables relaxation of the highly non-equilibrium ground state produced by fast internal conversion. In this dissertation, nonlinear spectroscopies carried out at cryogenic temperatures are used to uncover the particular nuclear modes in the solvent that primarily accept vibrational energy from
Sincore, Alex; Bodnar, Nathan; Bradford, Joshua; Abdulfattah, Ali; Shah, Lawrence; Richardson, Martin C.
2017-03-01
This work studies the accumulated nonlinearities when amplifying a narrow linewidth 2053 nm seed in a single mode Tm:fiber amplifier. A control of repetition rate and pulse duration (>30 ns). The pulses are subsequently amplified and the repetition rate is further reduced using a second acousto-optic modulator. It is well known that spectral degradation occurs in such fibers for peak powers over 100's of watts due to self-phase modulation, four-wave mixing, and stimulated Raman scattering. In addition to enabling a thorough test bed to study such spectral broadening, this system will also enable the investigation of stimulated Brillouin scattering thresholds in the same system. This detailed study of the nonlinearities encountered in 2 μm fiber amplifiers is important in a range of applications from telecommunications to the amplification of ultrashort laser pulses.
Institute of Scientific and Technical Information of China (English)
王玉华; 惠晓峰; 李敦亮
2014-01-01
本文应用非线性平滑转换回归模型研究了2002年1月份到2011年12月份我国与美国、欧元区、日本、韩国等有效汇率指数、综合利差之间的关系。实证分析表明，汇率对利率的影响具有明显的非对称性，具有较强的非线性转移动态特征。分国别看，四个国家或地区之间的上期利差均是影响本期利差的重要因素；在短期内汇率对利率影响较大。因此，短期内人民币汇率弹性的扩大应该主动、逐步、稳定进行，防止人民币汇率弹性的急剧扩大导致利率的过度波动。其次，逐步有序加快利率市场化进程并加强与汇率市场化的配合，构建高效的汇率-利率联动机制。%In order to analyze the relationship of interest rate and effective exchange rate , this paper uses the Smooth Transition Regression Model and then chooses the monthly data of these two variables of China 、USA、Eu-rozone、Japan and Korea from Jan .2002 to Dec.2011.The results show that exchange rate has a nonlinear influ-ence on interest rate and obvious asymmetry .The last month interest rate and exchange rate have an important influence on interest rate in these four countries .Based on this , in order to prevent the flexibility of exchange rate surge caused by excessive fluctuations of the interest rate , we should progressively and stablely take the initi-ative to expand the flexibility of exchange rate in the short term .Secondly , we should gradually speed up the process of interest rate and exchange rate co-ordination liberalization ,and build an efficient linkage system .
Rate process analysis of thermal damage in cartilage
Energy Technology Data Exchange (ETDEWEB)
Diaz, Sergio H; Nelson, J Stuart; Wong, Brian J F [Beckman Laser Institute and Medical Clinic, University of California, Irvine, CA (United States)
2003-01-07
Cartilage laser thermoforming (CLT) is a new surgical procedure that allows in situ treatment of deformities in the head and neck with less morbidity than traditional approaches. While some animal and human studies have shown promising results, the clinical feasibility of CLT depends on preservation of chondrocyte viability, which has not been extensively studied. The present paper characterizes cellular damage due to heat in rabbit nasal cartilage. Damage was modelled as a first order rate process for which two experimentally derived coefficients, A=1.2x10{sup 70} s{sup -1} and E{sub a}=4.5x10{sup 5} J mole{sup -1}, were determined by quantifying the decrease in concentration of healthy chondrocytes in tissue samples as a function of exposure time to constant-temperature water baths. After immersion, chondrocytes were enzymatically isolated from the matrix and stained with a two-component fluorescent dye. The dye binds nuclear DNA differentially depending upon chondrocyte viability. A flow cytometer was used to detect differential cell fluorescence to determine the percentage of live and dead cells in each sample. As a result, a damage kinetic model was obtained that can be used to predict the onset, extent and severity of cellular injury to thermal exposure.
Nonlinear Multiantenna Detection Methods
Directory of Open Access Journals (Sweden)
Chen Sheng
2004-01-01
Full Text Available A nonlinear detection technique designed for multiple-antenna assisted receivers employed in space-division multiple-access systems is investigated. We derive the optimal solution of the nonlinear spatial-processing assisted receiver for binary phase shift keying signalling, which we refer to as the Bayesian detector. It is shown that this optimal Bayesian receiver significantly outperforms the standard linear beamforming assisted receiver in terms of a reduced bit error rate, at the expense of an increased complexity, while the achievable system capacity is substantially enhanced with the advent of employing nonlinear detection. Specifically, when the spatial separation expressed in terms of the angle of arrival between the desired and interfering signals is below a certain threshold, a linear beamformer would fail to separate them, while a nonlinear detection assisted receiver is still capable of performing adequately. The adaptive implementation of the optimal Bayesian detector can be realized using a radial basis function network. Two techniques are presented for constructing block-data-based adaptive nonlinear multiple-antenna assisted receivers. One of them is based on the relevance vector machine invoked for classification, while the other on the orthogonal forward selection procedure combined with the Fisher ratio class-separability measure. A recursive sample-by-sample adaptation procedure is also proposed for training nonlinear detectors based on an amalgam of enhanced -means clustering techniques and the recursive least squares algorithm.
Nonlinear solution for radiation boundary condition of heat transfer process in human eye.
Dehghani, A; Moradi, A; Dehghani, M; Ahani, A
2011-01-01
In this paper we propose a new method based on finite element method for solving radiation boundary condition of heat equation inside the human eye and other applications. Using this method, we can solve heat equation inside human eye without need to model radiation boundary condition to a robin boundary condition. Using finite element method we can obtain a nonlinear equation, and finally we use nonlinear algorithm to solve it. The human eye is modeled as a composition of several homogeneous regions. The Ritz method in the finite element method is used for solving heat differential equation. Applying the boundary conditions, the heat radiation condition and the robin condition on the cornea surface of the eye and on the outer part of sclera are used, respectively. Simulation results of solving nonlinear boundary condition show the accuracy of the proposed method.
Nonlinear reflection process of linearly-polarized, broadband Alfv\\'en waves in the fast solar wind
Shoda, Munehito
2016-01-01
Using one-dimensional numerical simulations, we study the elementary process of Alfv\\'{e}n wave reflection in a uniform medium, including nonlinear effects. In the linear regime, Alfv\\'{e}n wave reflection is triggered only by the inhomogeneity of the medium, whereas in the nonlinear regime, it can occur via nonlinear wave-wave interactions. Such nonlinear reflection (backscattering) is typified by decay instability. In most studies of decay instabilities, the initial condition has been a circularly polarized Alfv\\'{e}n wave. In this study we consider a linearly polarized Alfv\\'en wave, which drives density fluctuations by its magnetic pressure force. For generality, we also assume a broadband wave with a red-noise spectrum. In the data analysis, we decompose the fluctuations into characteristic variables using local eigenvectors, thus revealing the behaviors of the individual modes. Different from circular-polarization case, we find that the wave steepening produces a new energy channel from the parent Alfv\\...
Koons, H. C.; Roeder, J. L.; Bauer, O. H.; Haerendel, G.; Treumann, R.
1987-01-01
Nonlinear wave decay processes have been detected in the solar wind by the plasma wave experiment aboard the Active Magnetospheric Particle Tracer Explorers (AMPTE) IRM spacecraft. The main process is the generation of ultralow-frequency ion acoustic waves from the decay of Langmuir waves near the electron plasma frequency. Frequently, this is accompanied by an enhancement of emissions near twice the plasma frequency. This enhancement is most likely due to the generation of electromagnetic waves from the coalescence of two Langmuir waves. These processes occur within the electron foreshock in front of the earth's bow shock.
Directory of Open Access Journals (Sweden)
Juan Eduardo González
2015-12-01
Full Text Available We present a scheme for conversion of pulsed light from the infrared to the red spectral region, using an aperiodically poled ferroelectric crystal within a resonant cavity in which two cascaded nonlinear optical processes occur when pumped with a pulsed Nd:YAG laser. This device emits 9 ns pulses of over 1 mJ at 710 nm and is a viable source for future biomedical applications.
Tene, Yair; Tene, Noam; Tene, G.
1993-08-01
An interactive data fusion methodology of video, audio, and nonlinear structural dynamic analysis for potential application in forensic engineering is presented. The methodology was developed and successfully demonstrated in the analysis of heavy transportable bridge collapse during preparation for testing. Multiple bridge elements failures were identified after the collapse, including fracture, cracks and rupture of high performance structural materials. Videotape recording by hand held camcorder was the only source of information about the collapse sequence. The interactive data fusion methodology resulted in extracting relevant information form the videotape and from dynamic nonlinear structural analysis, leading to full account of the sequence of events during the bridge collapse.
A 3-D nonlinear recursive digital filter for video image processing
Bauer, P. H.; Qian, W.
1991-01-01
This paper introduces a recursive 3-D nonlinear digital filter, which is capable of performing noise suppression without degrading important image information such as edges in space or time. It also has the property of unnoticeable bandwidth reduction immediately after a scene change, which makes the filter an attractive preprocessor to many interframe compression algorithms. The filter consists of a nonlinear 2-D spatial subfilter and a 1-D temporal filter. In order to achieve the required computational speed and increase the flexibility of the filter, all of the linear shift-variant filter modules are of the IIR type.
Yu, G. Y.; Luo, E. C.; Dai, W.; Hu, J. Y.
2007-10-01
This article focuses on using computational fluid dynamics (CFD) method to study several important nonlinear phenomenon and processes of a large experimental thermoacoustic-Stirling heat engine. First, the simulated physical model was introduced, and the suitable numerical scheme and algorithm for the time-dependent compressible thermoacoustic system was determined through extensive numerical tests. Then, the simulation results of the entire evolution process of self-excited thermoacoustic oscillation and the acoustical characteristics of pressure and velocity waves were presented and analyzed. Especially, the onset temperature and the saturation process of dynamic pressure were captured by the CFD simulation. In addition, another important nonlinear phenomenon accompanying the acoustic wave, which is the steady mass flow through the traveling-wave loop inside the thermoacoustic engine, was studied. To suppress the steady mass flow numerically, a fan model was adopted in the simulation. Finally, the multidimensional effects of vortex formation in the thermal buffer tube and other components were displayed numerically. Most importantly, a substantial comparison between the simulation and experiments was made, which demonstrated well the validity and powerfulness of the CFD simulation for characterizing several complicated nonlinear phenomenon involved in the self-excited thermoacoustic heat engine.
Detection limit for rate fluctuations in inhomogeneous Poisson processes
Shintani, Toshiaki; Shinomoto, Shigeru
2012-04-01
Estimations of an underlying rate from data points are inevitably disturbed by the irregular occurrence of events. Proper estimation methods are designed to avoid overfitting by discounting the irregular occurrence of data, and to determine a constant rate from irregular data derived from a constant probability distribution. However, it can occur that rapid or small fluctuations in the underlying density are undetectable when the data are sparse. For an estimation method, the maximum degree of undetectable rate fluctuations is uniquely determined as a phase transition, when considering an infinitely long series of events drawn from a fluctuating density. In this study, we analytically examine an optimized histogram and a Bayesian rate estimator with respect to their detectability of rate fluctuation, and determine whether their detectable-undetectable phase transition points are given by an identical formula defining a degree of fluctuation in an underlying rate. In addition, we numerically examine the variational Bayes hidden Markov model in its detectability of rate fluctuation, and determine whether the numerically obtained transition point is comparable to those of the other two methods. Such consistency among these three principled methods suggests the presence of a theoretical limit for detecting rate fluctuations.
Mathematical modeling suggests that periodontitis behaves as a non-linear chaotic dynamical process
Papantonopoulos, G.H.; Takahashi, K.; Bountis, T.; Loos, B.G.
2013-01-01
Background: This study aims to expand on a previously presented cellular automata model and further explore the non-linear dynamics of periodontitis. Additionally the authors investigated whether their mathematical model could predict the two known types of periodontitis, aggressive (AgP) and
The Nonlinear Interaction Process in the Wave Assimilation Model and Its Experiments
Institute of Scientific and Technical Information of China (English)
杨永增; 纪永刚; 袁业立
2003-01-01
This paper presents a composite interaction formula based on the discrete-interactionoperator of wave-wave nonlinear interaction for deriving its adjoint source function in the wave assimilation model. Assimilation experiments were performed using the significant wave heights observed by the TOPES/POSEIDON satellite, and the gradient distribution in the physical space wasalso analyzed preliminarily.
Mathematical modeling suggests that periodontitis behaves as a non-linear chaotic dynamical process
Papantonopoulos, G.H.; Takahashi, K.; Bountis, T.; Loos, B.G.
2013-01-01
Background: This study aims to expand on a previously presented cellular automata model and further explore the non-linear dynamics of periodontitis. Additionally the authors investigated whether their mathematical model could predict the two known types of periodontitis, aggressive (AgP) and chroni
Stellar neutron capture rates and the s process
Directory of Open Access Journals (Sweden)
Käppeler F.
2012-02-01
Full Text Available Neutron reactions are responsible for the formation of the elements heavier than iron. The corresponding scenarios relate to helium burning in Red Giant stars (s process and to supernova explosions (r and p processes. The s process, which operates in or near the valley of β-stability, has produced about half of the elemental abundances between Fe and Bi. Accurate (n, γ cross sections are the essential input for s process studies, because they determine the abundances produced by that process. Following a brief summary of the neutron capture processes, the focus will be set on the s process in massive stars, where the role of reliable cross section information is particularly important. Eventually, the intriguing aspects of the origin of 60Fe will be addressed. Attempts to determine the stellar cross section of that isotope are pushing experimental possibilities to their limits and present a pertinent challenge for future facilities.
Signorini, Maria G.
2014-01-01
Monitoring procedures are the basis to evaluate the clinical state of patients and to assess changes in their conditions, thus providing necessary interventions in time. Both these two objectives can be achieved by integrating technological development with methodological tools, thus allowing accurate classification and extraction of useful diagnostic information. The paper is focused on monitoring procedures applied to fetal heart rate variability (FHRV) signals, collected during pregnancy, in order to assess fetal well-being. The use of linear time and frequency techniques as well as the computation of non linear indices can contribute to enhancing the diagnostic power and reliability of fetal monitoring. The paper shows how advanced signal processing approaches can contribute to developing new diagnostic and classification indices. Their usefulness is evaluated by comparing two selected populations: normal fetuses and intra uterine growth restricted (IUGR) fetuses. Results show that the computation of different indices on FHRV signals, either linear and nonlinear, gives helpful indications to describe pathophysiological mechanisms involved in the cardiovascular and neural system controlling the fetal heart. As a further contribution, the paper briefly describes how the introduction of wearable systems for fetal ECG recording could provide new technological solutions improving the quality and usability of prenatal monitoring. PMID:24639886
Signorini, Maria G; Fanelli, Andrea; Magenes, Giovanni
2014-01-01
Monitoring procedures are the basis to evaluate the clinical state of patients and to assess changes in their conditions, thus providing necessary interventions in time. Both these two objectives can be achieved by integrating technological development with methodological tools, thus allowing accurate classification and extraction of useful diagnostic information. The paper is focused on monitoring procedures applied to fetal heart rate variability (FHRV) signals, collected during pregnancy, in order to assess fetal well-being. The use of linear time and frequency techniques as well as the computation of non linear indices can contribute to enhancing the diagnostic power and reliability of fetal monitoring. The paper shows how advanced signal processing approaches can contribute to developing new diagnostic and classification indices. Their usefulness is evaluated by comparing two selected populations: normal fetuses and intra uterine growth restricted (IUGR) fetuses. Results show that the computation of different indices on FHRV signals, either linear and nonlinear, gives helpful indications to describe pathophysiological mechanisms involved in the cardiovascular and neural system controlling the fetal heart. As a further contribution, the paper briefly describes how the introduction of wearable systems for fetal ECG recording could provide new technological solutions improving the quality and usability of prenatal monitoring.
Directory of Open Access Journals (Sweden)
Maria G. Signorini
2014-01-01
Full Text Available Monitoring procedures are the basis to evaluate the clinical state of patients and to assess changes in their conditions, thus providing necessary interventions in time. Both these two objectives can be achieved by integrating technological development with methodological tools, thus allowing accurate classification and extraction of useful diagnostic information. The paper is focused on monitoring procedures applied to fetal heart rate variability (FHRV signals, collected during pregnancy, in order to assess fetal well-being. The use of linear time and frequency techniques as well as the computation of non linear indices can contribute to enhancing the diagnostic power and reliability of fetal monitoring. The paper shows how advanced signal processing approaches can contribute to developing new diagnostic and classification indices. Their usefulness is evaluated by comparing two selected populations: normal fetuses and intra uterine growth restricted (IUGR fetuses. Results show that the computation of different indices on FHRV signals, either linear and nonlinear, gives helpful indications to describe pathophysiological mechanisms involved in the cardiovascular and neural system controlling the fetal heart. As a further contribution, the paper briefly describes how the introduction of wearable systems for fetal ECG recording could provide new technological solutions improving the quality and usability of prenatal monitoring.
Directory of Open Access Journals (Sweden)
P. Y. Rogov
2015-09-01
Full Text Available The paper deals with mathematical model of linear and nonlinear processes occurring at the propagation of femtosecond laser pulses in the vitreous of the human eye. Methods of computing modeling are applied for the nonlinear spectral equation solution describing the dynamics of a two-dimensional TE-polarized radiation in a homogeneous isotropic medium with cubic fast-response nonlinearity without the usage of slowly varying envelope approximation. Environments close to the optical media parameters of the eye were used for the simulation. The model of femtosecond radiation propagation takes into account the process dynamics for dispersion broadening of pulses in time and the occurence of the self-focusing near the retina when passing through the vitreous body of the eye. Dependence between the pulse duration on the retina has been revealed and the duration of the input pulse and the values of power density at which there is self-focusing have been found. It is shown that the main mechanism of radiation damage with the use of titanium-sapphire laser is photoionization. The results coincide with those obtained by the other scientists, and are usable for creation Russian laser safety standards for femtosecond laser systems.
Directory of Open Access Journals (Sweden)
V.C. Kunz
2012-05-01
Full Text Available The objectives of this study were to evaluate and compare the use of linear and nonlinear methods for analysis of heart rate variability (HRV in healthy subjects and in patients after acute myocardial infarction (AMI. Heart rate (HR was recorded for 15 min in the supine position in 10 patients with AMI taking β-blockers (aged 57 ± 9 years and in 11 healthy subjects (aged 53 ± 4 years. HRV was analyzed in the time domain (RMSSD and RMSM, the frequency domain using low- and high-frequency bands in normalized units (nu; LFnu and HFnu and the LF/HF ratio and approximate entropy (ApEn were determined. There was a correlation (P < 0.05 of RMSSD, RMSM, LFnu, HFnu, and the LF/HF ratio index with the ApEn of the AMI group on the 2nd (r = 0.87, 0.65, 0.72, 0.72, and 0.64 and 7th day (r = 0.88, 0.70, 0.69, 0.69, and 0.87 and of the healthy group (r = 0.63, 0.71, 0.63, 0.63, and 0.74, respectively. The median HRV indexes of the AMI group on the 2nd and 7th day differed from the healthy group (P < 0.05: RMSSD = 10.37, 19.95, 24.81; RMSM = 23.47, 31.96, 43.79; LFnu = 0.79, 0.79, 0.62; HFnu = 0.20, 0.20, 0.37; LF/HF ratio = 3.87, 3.94, 1.65; ApEn = 1.01, 1.24, 1.31, respectively. There was agreement between the methods, suggesting that these have the same power to evaluate autonomic modulation of HR in both AMI patients and healthy subjects. AMI contributed to a reduction in cardiac signal irregularity, higher sympathetic modulation and lower vagal modulation.
Poor glycemic control impacts linear and non-linear dynamics of heart rate in DM type 2
Directory of Open Access Journals (Sweden)
Daniela Bassi
2015-08-01
Full Text Available INTRODUCTION: It is well known that type 2 diabetes mellitus (T2DM produces cardiovascular autonomic neuropathy (CAN, which may affect the cardiac autonomic modulation. However, it is unclear whether the lack of glycemic control in T2DM without CAN could impact negatively on cardiac autonomic modulation. Objective: To evaluate the relationship between glycemic control and cardiac autonomic modulation in individuals with T2DM without CAN. Descriptive, prospective and cross sectional study.METHODS: Forty-nine patients with T2DM (51±7 years were divided into two groups according to glycosylated hemoglobin (HbA1c: G1≤7% and G2>7.0%. Resting heart rate (HR and RR interval (RRi were obtained and calculated by linear (Mean iRR; Mean HR; rMSSD; STD RR; LF; HF; LF/HF, TINN and RR Tri, and non-linear (SD1; SD2; DFα1; DFα2, Shannon entropy; ApEn; SampEn and CD methods of heart rate variability (HRV. Insulin, HOMA-IR, fasting glucose and HbA1c were obtained by blood tests.RESULTS: G2 (HbA1c≤7% showed lower values for the mean of iRR; STD RR; RR Tri, TINN, SD2, CD and higher mean HR when compared with G1 (HbA1c > 7%. Additionally, HbA1c correlated negatively with mean RRi (r=0.28, p=0.044; STD RR (r=0.33, p=0.017; RR Tri (r=-0.35, p=0.013, SD2 (r=-0.39, p=0.004 and positively with mean HR (r=0.28, p=0.045. Finally, fasting glucose correlated negatively with STD RR (r=-0.36, p=0.010; RR Tri (r=-0.36, p=0.010; TINN (r=-0.33, p=0.019 and SD2 (r=-0.42, p=0.002.CONCLUSION: We concluded that poor glycemic control is related to cardiac autonomic modulation indices in individuals with T2DM even if they do not present cardiovascular autonomic neuropathy.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Dual-point composition control for a high-purity ideal heat integrated distillation column (HIDiC) is addressed in this work. Three measures are suggested and combined for overcoming process inherent nonlinearities:(1) variable scaling; (2) multi-model representation of process dynamics and (3) feedforward compensation. These strategies can offer the developed control systems with several distinct advantages: (1) capability of dealing with severe disturbances; (2) tight tuning of controller parameters and (3) high robustness with respect to variation of operating conditions. Simulation results demonstrate the effectiveness of the proposed methodology.
Rate-optimal Bayesian intensity smoothing for inhomogeneous Poisson processes
E. Belitser; P. Serra; H. van Zanten
2015-01-01
We apply nonparametric Bayesian methods to study the problem of estimating the intensity function of an inhomogeneous Poisson process. To motivate our results we start by analyzing count data coming from a call center which we model as a Poisson process. This analysis is carried out using a certain
Generalized Nonlinear Yule Models
Lansky, Petr; Polito, Federico; Sacerdote, Laura
2016-10-01
With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.
Generalized Nonlinear Yule Models
Lansky, Petr; Polito, Federico; Sacerdote, Laura
2016-11-01
With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.
Directory of Open Access Journals (Sweden)
E. D. Resende
2007-09-01
Full Text Available The freezing process is considered as a propagation problem and mathematically classified as an "initial value problem." The mathematical formulation involves a complex situation of heat transfer with simultaneous changes of phase and abrupt variation in thermal properties. The objective of the present work is to solve the non-linear heat transfer equation for food freezing processes using orthogonal collocation on finite elements. This technique has not yet been applied to freezing processes and represents an alternative numerical approach in this area. The results obtained confirmed the good capability of the numerical method, which allows the simulation of the freezing process in approximately one minute of computer time, qualifying its application in a mathematical optimising procedure. The influence of the latent heat released during the crystallisation phenomena was identified by the significant increase in heat load in the early stages of the freezing process.
Mean level signal crossing rate for an arbitrary stochastic process.
Yura, Harold T; Hanson, Steen G
2010-04-01
The issue of the mean signal level crossing rate for various probability density functions with primary relevance for optics is discussed based on a new analytical method. This method relies on a unique transformation that transforms the probability distribution under investigation into a normal probability distribution, for which the distribution of mean level crossings is known. In general, the analytical results for the mean level crossing rate are supported and confirmed by numerical simulations. In particular, we illustrate the present method by presenting analytic expressions for the mean level crossing rate for various probability distributions, including ones that previously were unavailable, such as the uniform, the so-called gamma-gamma, and the Rice-Nakagami distribution. However, in a limited number of cases the present results differ somewhat from the result reported in the literature. At present, this discrepancy remains unexplained and is laid open for future discussion.
Mean level signal crossing rate for an arbitrary stochastic process
DEFF Research Database (Denmark)
Yura, Harold T.; Hanson, Steen Grüner
2010-01-01
The issue of the mean signal level crossing rate for various probability density functions with primary relevance for optics is discussed based on a new analytical method. This method relies on a unique transformation that transforms the probability distribution under investigation into a normal...... probability distribution, for which the distribution of mean level crossings is known. In general, the analytical results for the mean level crossing rate are supported and confirmed by numerical simulations. In particular, we illustrate the present method by presenting analytic expressions for the mean level...... crossing rate for various probability distributions, including ones that previously were unavailable, such as the uniform, the so-called gamma-gamma, and the Rice–Nakagami distribution. However, in a limited number of cases the present results differ somewhat from the result reported in the literature...
Optimisation of Construction Process Inspection Rates using a Learning Approach
Directory of Open Access Journals (Sweden)
Swapan Saha
2012-11-01
Full Text Available In the construction industry, the determination of the number of inspections/tests to be performed for a repetitive task is an important issue. The quality of a completed task depends on a number of factors including the cost of inspection, the cost of failure, the average proportion defective (error rate and the inspection rate. To achieve a higher quality level, 100% inspection can be performed, however, this is unlikely to be cost effective. To determine the optimum inspection rate, this paper suggests a probabilistic approach incorporating the acceptance-sampling plan and minimum cost method. The limitation of various sampling plans including the attribute proportional sampling plan and the double sampling plan are outlined. An example is presented in this paper to demonstrate the calculation of the optimum number of inspections/tests per lot.
Nonlinear analysis on the coupling process of electromagnetic vibrator and earth
Institute of Scientific and Technical Information of China (English)
CHEN; Zubin; TENG; Jiwen; LIN; Jun; ZHANG; Linhang; JIANG
2005-01-01
The linear model based on the hydraulic pressure vibrator has been no longer adaptable to the electromagnetic vibrator. In order to realize the effective transmission of the limited energy from the vibrator to the ground, it is important to study the coupling model of the electromagnetic vibrator and the earth. In this paper, a nonlinear restore term was introduced to the coupling model because of the existence of a large amount of harmonics in the vibrator baseplate. The nonlinear vibration analysis was applied to the model by the multiscale method. In the course of energy transmission from the vibrator to the ground, ultraharmonic resonance was used to explain the generation of harmonics. An improved scheme was advanced to select the cross correlation reference signal in the vibrator seismic exploration. Good application results were obtained in field experiments.
Non-linear processes in thin titanium nitride transmission lines for parametric amplification
Vissers, Michael; Gao, Jiansong; Chaudhuri, Suptarshi; Bockstiegel, Clint; Sandberg, Martin; Pappas, David P.
2013-03-01
Nitride superconductors, such as titanium nitride and niobium titanium nitride, are a non-linear, low dissipation medium at microwave frequencies. The lossless nonlinearity may be probed and utilized. Important applications include generation of higher harmonics, e.g. 3f, and a microwave version of the optical paramagnetic amplifier, i.e. the degenerate-pump case of four-photon mixing (FPM). An amplifier based on these principles should allow for very wide bandwidth, low noise (quantum limited) and high dynamic range devices. These measurements are performed via a single layer, 3 meter long TiN spiral and measured at temperatures below 100 mK. Initial results of the design, fabrication, testing, and impedance optimization of a titanium nitride based parametric amplifier are presented.
Partial and total actuator faults accommodation for input-affine nonlinear process plants.
Mihankhah, Amin; Salmasi, Farzad R; Salahshoor, Karim
2013-05-01
In this paper, a new fault-tolerant control system is proposed for input-affine nonlinear plants based on Model Reference Adaptive System (MRAS) structure. The proposed method has the capability to accommodate both partial and total actuator failures along with bounded external disturbances. In this methodology, the conventional MRAS control law is modified by augmenting two compensating terms. One of these terms is added to eliminate the nonlinear dynamic, while the other is reinforced to compensate the distractive effects of the total actuator faults and external disturbances. In addition, no Fault Detection and Diagnosis (FDD) unit is needed in the proposed method. Moreover, the control structure has good robustness capability against the parameter variation. The performance of this scheme is evaluated using a CSTR system and the results were satisfactory.
Rate Theory for Correlated Processes: Double Jumps in Adatom Diffusion
DEFF Research Database (Denmark)
Jacobsen, J.; Jacobsen, Karsten Wedel; Sethna, J.
1997-01-01
We study the rate of activated motion over multiple barriers, in particular the correlated double jump of an adatom diffusing on a missing-row reconstructed platinum (110) surface. We develop a transition path theory, showing that the activation energy is given by the minimum-energy trajectory...... which succeeds in the double jump. We explicitly calculate this trajectory within an effective-medium molecular dynamics simulation. A cusp in the acceptance region leads to a root T prefactor for the activated rate of double jumps. Theory and numerical results agree....
Noury, Nima; Hipp, Joerg F; Siegel, Markus
2016-10-15
Transcranial electric stimulation (tES) is a promising tool to non-invasively manipulate neuronal activity in the human brain. Several studies have shown behavioral effects of tES, but stimulation artifacts complicate the simultaneous investigation of neural activity with EEG or MEG. Here, we first show for EEG and MEG, that contrary to previous assumptions, artifacts do not simply reflect stimulation currents, but that heartbeat and respiration non-linearly modulate stimulation artifacts. These modulations occur irrespective of the stimulation frequency, i.e. during both transcranial alternating and direct current stimulations (tACS and tDCS). Second, we show that, although at first sight previously employed artifact rejection methods may seem to remove artifacts, data are still contaminated by non-linear stimulation artifacts. Because of their complex nature and dependence on the subjects' physiological state, these artifacts are prone to be mistaken as neural entrainment. In sum, our results uncover non-linear tES artifacts, show that current techniques fail to fully remove them, and pave the way for new artifact rejection methods.
Module energy rating candidate reference days: Criteria and selection process
Myers, Daryl R.
1999-03-01
Presently the performance of flat-plate photovoltaic (PV) modules is based upon module power, open circuit voltage, short-circuit current, or peak power voltage and current with respect to fixed environmental conditions such as Standard Reporting Conditions, (SRC) or nominal operating cell temperature. These reporting conditions represent ideal conditions under which PV module performance (e.g., between manufacturers or technologies) may be compared. They result in overly optimistic expectations of performance by PV industry customers. A recommended practice for PV module energy-rating methodologies to relate PV module performance to real world conditions is under development. The methodologies will provide system designers and PV customers with an energy rating representative of real world conditions. The rating methodology reports energy production under 5 selected types of days representative of possible operational environments. The development and application of qualitative and quantitative criteria for identifying and selecting these representative days from the 30-year U.S. National Solar Radiation Data Base is described.
Directory of Open Access Journals (Sweden)
Maruthai Suresh
2010-10-01
Full Text Available A nonlinear process, the heat exchanger whose parameters vary with respect to the process variable, is considered. The time constant and gain of the chosen process vary as a function of temperature. The limitations of the conventional feedback controller tuned using Ziegler-Nichols settings for the chosen process are brought out. The servo and regulatory responses through simulation and experimentation for various magnitudes of set-point changes and load changes at various operating points with the controller tuned only at a chosen nominal operating point are obtained and analyzed. Regulatory responses for output load changes are studied. The efficiency of feedforward controller and the effects of modeling error have been brought out. An IMC based system is presented to understand clearly how variations of system parameters affect the performance of the controller. The present work illustrates the effectiveness of Feedforward and IMC controller.
Energy Technology Data Exchange (ETDEWEB)
Bibler, N.E.
1992-11-12
Hydrogen production from radiolysis of aqueous solutions can create a safety hazard since hydrogen is flammable. At times this production can be significant, especially in HB line where nitric acid solutions containing high concentrations of Pu-238, an intense alpha emitter, are processed. The hydrogen production rates from these solutions are necessary for safety analyses of these process systems. The methods and conclusions of hydrogen production rate tests are provided in this report.
Reconciling Estimates of Earnings Processes in Growth Rates and Levels
DEFF Research Database (Denmark)
Daly, Moira; Hryshko, Dmytro; Manovskii, Iourii
The stochastic process for earnings is the key element of incomplete markets models in modern quantitative macroeconomics. It determines both the equilibrium distributions of endogenous outcomes and the design of optimal policies. Yet, there is no consensus in the literature on the relative...
High Metal Removal Rate Process for Machining Difficult Materials
Energy Technology Data Exchange (ETDEWEB)
Bates, Robert; McConnell, Elizabeth
2016-06-29
Machining methods across many industries generally require multiple operations to machine and process advanced materials, features with micron precision, and complex shapes. The resulting multiple machining platforms can significantly affect manufacturing cycle time and the precision of the final parts, with a resultant increase in cost and energy consumption. Ultrafast lasers represent a transformative and disruptive technology that removes material with micron precision and in a single step manufacturing process. Such precision results from athermal ablation without modification or damage to the remaining material which is the key differentiator between ultrafast laser technologies and traditional laser technologies or mechanical processes. Athermal ablation without modification or damage to the material eliminates post-processing or multiple manufacturing steps. Combined with the appropriate technology to control the motion of the work piece, ultrafast lasers are excellent candidates to provide breakthrough machining capability for difficult-to-machine materials. At the project onset in early 2012, the project team recognized that substantial effort was necessary to improve the application of ultrafast laser and precise motion control technologies (for micromachining difficult-to-machine materials) to further the aggregate throughput and yield improvements over conventional machining methods. The project described in this report advanced these leading-edge technologies thru the development and verification of two platforms: a hybrid enhanced laser chassis and a multi-application testbed.
Fast optical signal processing in high bit rate OTDM systems
DEFF Research Database (Denmark)
Poulsen, Henrik Nørskov; Jepsen, Kim Stokholm; Clausen, Anders;
1998-01-01
As all-optical signal processing is maturing, optical time division multiplexing (OTDM) has also gained interest for simple networking in high capacity backbone networks. As an example of a network scenario we show an OTDM bus interconnecting another OTDM bus, a single high capacity user...
Schertzer, D.; Lovejoy, S.
1. The conference The third conference on "Nonlinear VAriability in Geophysics: scaling and multifractal processes" (NVAG 3) was held in Cargese, Corsica, Sept. 10-17, 1993. NVAG3 was joint American Geophysical Union Chapman and European Geophysical Society Richardson Memorial conference, the first specialist conference jointly sponsored by the two organizations. It followed NVAG1 (Montreal, Aug. 1986), NVAG2 (Paris, June 1988; Schertzer and Lovejoy, 1991), five consecutive annual sessions at EGS general assemblies and two consecutive spring AGU meeting sessions. As with the other conferences and workshops mentioned above, the aim was to develop confrontation between theories and experiments on scaling/multifractal behaviour of geophysical fields. Subjects covered included climate, clouds, earthquakes, atmospheric and ocean dynamics, tectonics, precipitation, hydrology, the solar cycle and volcanoes. Areas of focus included new methods of data analysis (especially those used for the reliable estimation of multifractal and scaling exponents), as well as their application to rapidly growing data bases from in situ networks and remote sensing. The corresponding modelling, prediction and estimation techniques were also emphasized as were the current debates about stochastic and deterministic dynamics, fractal geometry and multifractals, self-organized criticality and multifractal fields, each of which was the subject of a specific general discussion. The conference started with a one day short course of multifractals featuring four lectures on a) Fundamentals of multifractals: dimension, codimensions, codimension formalism, b) Multifractal estimation techniques: (PDMS, DTM), c) Numerical simulations, Generalized Scale Invariance analysis, d) Advanced multifractals, singular statistics, phase transitions, self-organized criticality and Lie cascades (given by D. Schertzer and S. Lovejoy, detailed course notes were sent to participants shortly after the conference). This
Directory of Open Access Journals (Sweden)
D. Schertzer
1994-01-01
Full Text Available 1. The conference The third conference on "Nonlinear VAriability in Geophysics: scaling and multifractal processes" (NVAG 3 was held in Cargese, Corsica, Sept. 10-17, 1993. NVAG3 was joint American Geophysical Union Chapman and European Geophysical Society Richardson Memorial conference, the first specialist conference jointly sponsored by the two organizations. It followed NVAG1 (Montreal, Aug. 1986, NVAG2 (Paris, June 1988; Schertzer and Lovejoy, 1991, five consecutive annual sessions at EGS general assemblies and two consecutive spring AGU meeting sessions. As with the other conferences and workshops mentioned above, the aim was to develop confrontation between theories and experiments on scaling/multifractal behaviour of geophysical fields. Subjects covered included climate, clouds, earthquakes, atmospheric and ocean dynamics, tectonics, precipitation, hydrology, the solar cycle and volcanoes. Areas of focus included new methods of data analysis (especially those used for the reliable estimation of multifractal and scaling exponents, as well as their application to rapidly growing data bases from in situ networks and remote sensing. The corresponding modelling, prediction and estimation techniques were also emphasized as were the current debates about stochastic and deterministic dynamics, fractal geometry and multifractals, self-organized criticality and multifractal fields, each of which was the subject of a specific general discussion. The conference started with a one day short course of multifractals featuring four lectures on a Fundamentals of multifractals: dimension, codimensions, codimension formalism, b Multifractal estimation techniques: (PDMS, DTM, c Numerical simulations, Generalized Scale Invariance analysis, d Advanced multifractals, singular statistics, phase transitions, self-organized criticality and Lie cascades (given by D. Schertzer and S. Lovejoy, detailed course notes were sent to participants shortly after the
DEFF Research Database (Denmark)
Koefoed, Jacob Gade; Christensen, Jesper Bjerge; Rottwitt, Karsten
2017-01-01
We present a general model, based on a Hamiltonian approach, for the joint quantum state of photon pairs generated through pulsed spontaneous four-wave mixing, including nonlinear phase modulation and a finite material response time. For the case of a silica fiber, it is found that the pair......-dependent change in quantum-mechanical purity may be observed in silica. This shows that Raman scattering not only introduces noise, but can also drastically change the spectral correlations in photon pairs when pumped with short pulses....
Institute of Scientific and Technical Information of China (English)
CHEN Yu-Li; LIU Bin; YIN Ya-Jun; HUANG Yong-Gang; HWUANG Keh-Chih
2008-01-01
The tensile deformations and fractures of super carbon nanotubes (SCNTs) with armchair-armchair topology are investigated by using the atomic-scale finite element method. SCNTs generated from carbon nanotubes (CNTs) with different characteristic aspect ratios are found to have different nonlinear behaviours under uniaxiai tensions. Specifically, an SCNT with higher aspect ratio has three distinct stages: rotation, stretch and rupture, while an SCNT with lower aspect ratio has only two stages. This information may compensate for previous work and enrich our knowledge about Y-branched CNTs and SCNTs.
Ding, Shun-Liang; Song, En-Zhe; Yang, Li-Ping; Yao, Chong; Ma, Xiu-Zhen
2017-02-01
The nonlinear dynamics of the combustion process in the lean-burn premixed natural gas engine are studied in this paper. Based on nonlinear dynamic theory, the complexity of the combustion process is analyzed under different injection timing conditions. The phase spaces are reconstructed for the experimentally obtained in-cylinder pressure real-time series and the return maps are plotted for the IMEP time series. The results of phase space reconstruction manifest that the attractors are limited to the finite range in the reconstructed phase space. The attractors have a folded and twist geometry structure. The attractors under medium injection timing conditions are looser and more complex. The return maps indicate the coexistence of the stochastic and deterministic components in the patterns combustion process. With the injection timing increasing, there are both a transition from stochastic to deterministic and a transition from deterministic to stochastic, forming the region of deterministic behavior. The largest Lyapunov exponents (LLE) for in-cylinder pressure time series are calculated and the coefficients of variations (COV) of IMEP are also analyzed. The results express that the LLE values are positive. There are a "steep increase" and a "steep decrease" for the LLE and COV values as the injection timing increasing.
Liu, Li; Wan, Jieqiu
2012-12-01
This paper explores the co-movement of Shanghai stock market and China Yuan (CNY) exchange rates. First, we find that stock price and exchange rate are significantly cross-correlated. Second, employing a cointegration test allowing for a structural break, we find that the Shanghai Composite Index (SCI) is not cointegrated with the exchange rate of CNY/USD. The so-called “cointegration” found in previous studies is just caused by the shock of the recent financial crisis. Third, using linear and nonlinear Granger causality tests, we find no causality between stock prices and exchange rates during the period before the recent financial crisis. After the financial crisis, a unidirectional causality behavior running from exchange rates to stock index is present.
Finite-dimensional constrained fuzzy control for a class of nonlinear distributed process systems.
Wu, Huai-Ning; Li, Han-Xiong
2007-10-01
This correspondence studies the problem of finite-dimensional constrained fuzzy control for a class of systems described by nonlinear parabolic partial differential equations (PDEs). Initially, Galerkin's method is applied to the PDE system to derive a nonlinear ordinary differential equation (ODE) system that accurately describes the dynamics of the dominant (slow) modes of the PDE system. Subsequently, a systematic modeling procedure is given to construct exactly a Takagi-Sugeno (T-S) fuzzy model for the finite-dimensional ODE system under state constraints. Then, based on the T-S fuzzy model, a sufficient condition for the existence of a stabilizing fuzzy controller is derived, which guarantees that the state constraints are satisfied and provides an upper bound on the quadratic performance function for the finite-dimensional slow system. The resulting fuzzy controllers can also guarantee the exponential stability of the closed-loop PDE system. Moreover, a local optimization algorithm based on the linear matrix inequalities is proposed to compute the feedback gain matrices of a suboptimal fuzzy controller in the sense of minimizing the quadratic performance bound. Finally, the proposed design method is applied to the control of the temperature profile of a catalytic rod.
Rapid prediction method for nonlinear expansion process of medical vascular stent
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
A neural network model with high nonlinear recognition capability was constructed to describe the relationship between the deformation impact factors and the deformation results of vascular stent.Then,using the weighted correction method with the attached momentum term,the network training algorithm was optimized by introducing learning factor η and momentum factor ψ,so the speed of the network training and the system robustness were enhanced.The network was trained by some practi-cal cases,and the statistical hypothesis validation was made for the predictive errors.It was shown that the average difference between the intelligent predictive result of vascular stent deformation neu-ral network and the nonlinear finite element analysis result was less than 0.03%,and the trained net-work could perfectly predict the vascular stent deformation.Further more,the rapid evaluation tool for the vascular stent mechanics performance was established using the Pro/Toolkit and the intelligent neural network predictive model of vascular stent expansion.The proposed tool system with strong practicality and high efficiency can significantly shorten the product development cycle of vascular stent.
Reconciling Estimates of Earnings Processes in Growth Rates and Levels
DEFF Research Database (Denmark)
Daly, Moira; Hryshko, Dmytro; Manovskii, Iourii
The stochastic process for earnings is the key element of incomplete markets models in modern quantitative macroeconomics. It determines both the equilibrium distributions of endogenous outcomes and the design of optimal policies. Yet, there is no consensus in the literature on the relative...... magnitudes of the permanent and transitory innovations in earnings. When estimation is based on the earnings moments in levels, the variance of transitory shocks is found to be relatively high. When the moments in differences are used, the variance of the permanent component is relatively high instead. We...... of earnings spells quantitatively accounts for the full amount of discrepancy in the estimates. Using data from the Panel Study of Income Dynamics, we show that this property of earnings induces a substantial upward bias in the estimate of consumption insurance against permanent shocks....
Medvedev, A P; Gavrilushkin, A P; Kiselev, S V; Shelepnev, A V; Smirnov, N A
2001-01-01
An examination of 39 patients with heart diseases was performed before and after operations by the method of geometrical analysis of the nonlinear chaos (fractal) variability of the cardiac rhythm on the basis of the apparatus-programmed complex "Poly-spectrum". Five-minute-long registrations of ECG were carried on. On the basis of the data of examination of 195 healthy volunteers the reference norm of this method parameters was determined. Reliably lower parameters were found in patients with the acquired valvular disease. A dynamic investigation of the geometrical nonlinear structure of the cardiac rhythm has shown the possibility to make a prognosis of early complications after prosthetics of the heart valves.
Does the aging process significantly modify the Mean Heart Rate?
Santos, Marcos Antonio Almeida; Sousa, Antonio Carlos Sobral; Reis, Francisco Prado; Santos, Thayná Ramos; Lima, Sonia Oliveira; Barreto-Filho, José Augusto
2013-11-01
The Mean Heart Rate (MHR) tends to decrease with age. When adjusted for gender and diseases, the magnitude of this effect is unclear. To analyze the MHR in a stratified sample of active and functionally independent individuals. A total of 1,172 patients aged > 40 years underwent Holter monitoring and were stratified by age group: 1 = 40-49, 2 = 50-59, 3 = 60-69, 4 = 70-79, 5 = > 80 years. The MHR was evaluated according to age and gender, adjusted for Hypertension (SAH), dyslipidemia and non-insulin dependent diabetes mellitus (NIDDM). Several models of ANOVA, correlation and linear regression were employed. A two-tailed p value MHR tended to decrease with the age range: 1 = 77.20 ± 7.10; 2 = 76.66 ± 7.07; 3 = 74.02 ± 7.46; 4 = 72.93 ± 7.35; 5 = 73.41 ± 7.98 (p MHR (p MHR decreased with age. Women had higher values of MHR, regardless of the age group. Correlations between MHR and age or gender, albeit significant, showed the effect magnitude had little statistical relevance. The prevalence of SAH, dyslipidemia and diabetes mellitus did not influence the results.
Seider, Warren D.; Ungar, Lyle H.
1987-01-01
Describes a course in nonlinear mathematics courses offered at the University of Pennsylvania which provides an opportunity for students to examine the complex solution spaces that chemical engineers encounter. Topics include modeling many chemical processes, especially those involving reaction and diffusion, auto catalytic reactions, phase…
Chen, Chun-I.; Chen, Hong Long; Chen, Shuo-Pei
2008-08-01
The traditional Grey Model is easy to understand and simple to calculate, with satisfactory accuracy, but it is also lack of flexibility to adjust the model to acquire higher forecasting precision. This research studies feasibility and effectiveness of a novel Grey model together with the concept of the Bernoulli differential equation in ordinary differential equation. In this research, the author names this newly proposed model as Nonlinear Grey Bernoulli Model (NGBM). The NGBM is nonlinear differential equation with power index n. By controlling n, the curvature of the solution curve could be adjusted to fit the result of one time accumulated generating operation (1-AGO) of raw data. One extreme case from Grey system textbook is studied by NGBM, and two published articles are chosen for practical tests of NGBM. The results prove the novel NGBM is feasible and efficient. Finally, NGBM is used to forecast 2005 foreign exchange rates of twelve Taiwan major trading partners, including Taiwan.
Nonlinear Growth Curves in Developmental Research
Grimm, Kevin J.; Ram, Nilam; Hamagami, Fumiaki
2011-01-01
Developmentalists are often interested in understanding change processes, and growth models are the most common analytic tool for examining such processes. Nonlinear growth curves are especially valuable to developmentalists because the defining characteristics of the growth process such as initial levels, rates of change during growth spurts, and…
Grigoryeva, Lyudmila; Henriques, Julie; Larger, Laurent; Ortega, Juan-Pablo
2016-07-01
This letter addresses the reservoir design problem in the context of delay-based reservoir computers for multidimensional input signals, parallel architectures, and real-time multitasking. First, an approximating reservoir model is presented in those frameworks that provides an explicit functional link between the reservoir architecture and its performance in the execution of a specific task. Second, the inference properties of the ridge regression estimator in the multivariate context are used to assess the impact of finite sample training on the decrease of the reservoir capacity. Finally, an empirical study is conducted that shows the adequacy of the theoretical results with the empirical performances exhibited by various reservoir architectures in the execution of several nonlinear tasks with multidimensional inputs. Our results confirm the robustness properties of the parallel reservoir architecture with respect to task misspecification and parameter choice already documented in the literature.
THz Generation by Optical Rectification and Competition with Other Nonlinear Processes
Institute of Scientific and Technical Information of China (English)
ZHAO Zhen-Yu; HAMEAU Sophie; TIGNON Jér(o)me
2008-01-01
We present a study of the competition between tera-hertz (THz) generation by optical rectification in (110)Zn Te crystals,two-photon absorption,second harmonic generation and flee-carrier absorption.The two-photon nonlinear absorption coefficient,second harmonic generation efficiency and flee-carrier absorption coefficient in the THz range are measured independently.The incident pump field is shown to be depleted by two-photon absorption and the THz radiation is shown to be reduced,upon focusing,by free-carrier absorption.The reduction of the generated THz radiation upon tight focusing is explained,provided that one also takes into account diffraction effects from the sub-wavelength THz source.
Jamali, A.; Khaleghi, E.; Gholaminezhad, I.; Nariman-zadeh, N.
2016-05-01
In this paper, a new multi-objective genetic programming (GP) with a diversity preserving mechanism and a real number alteration operator is presented and successfully used for Pareto optimal modelling of some complex non-linear systems using some input-output data. In this study, two different input-output data-sets of a non-linear mathematical model and of an explosive cutting process are considered separately in three-objective optimisation processes. The pertinent conflicting objective functions that have been considered for such Pareto optimisations are namely, training error (TE), prediction error (PE), and the length of tree (complexity of the network) (TL) of the GP models. Such three-objective optimisation implementations leads to some non-dominated choices of GP-type models for both cases representing the trade-offs among those objective functions. Therefore, optimal Pareto fronts of such GP models exhibit the trade-off among the corresponding conflicting objectives and, thus, provide different non-dominated optimal choices of GP-type models. Moreover, the results show that no significant optimality in TE and PE may occur when the TL of the corresponding GP model exceeds some values.
Barros, A. P.; Wilson, A. M.; Miller, D. K.; Tao, J.; Genereux, D. P.; Prat, O.; Petersen, W. A.; Brunsell, N. A.; Petters, M. D.; Duan, Y.
2015-12-01
Using the planet as a study domain and collecting observations over unprecedented ranges of spatial and temporal scales, NASA's EOS (Earth Observing System) program was an agent of transformational change in Earth Sciences over the last thirty years. The remarkable space-time organization and variability of atmospheric and terrestrial moist processes that emerged from the analysis of comprehensive satellite observations provided much impetus to expand the scope of land-atmosphere interaction studies in Hydrology and Hydrometeorology. Consequently, input and output terms in the mass and energy balance equations evolved from being treated as fluxes that can be used as boundary conditions, or forcing, to being viewed as dynamic processes of a coupled system interacting at multiple scales. Measurements of states or fluxes are most useful if together they map, reveal and/or constrain the underlying physical processes and their interactions. This can only be accomplished through an integrated observing system designed to capture the coupled physics, including nonlinear feedbacks and tipping points. Here, we first review and synthesize lessons learned from hydrometeorology studies in the Southern Appalachians and in the Southern Great Plains using both ground-based and satellite observations, physical models and data-assimilation systems. We will specifically focus on mapping and understanding nonlinearity and multiscale memory of rainfall-runoff processes in mountainous regions. It will be shown that beyond technical rigor, variety, quantity and duration of measurements, the utility of observing systems is determined by their interpretive value in the context of physical models to describe the linkages among different observations. Second, we propose a framework for designing science-grade and science-minded process-oriented integrated observing and modeling platforms for hydrometeorological studies.
78 FR 21521 - Pears Grown in Oregon and Washington; Assessment Rate Decrease for Processed Pears
2013-04-11
... Agricultural Marketing Service 7 CFR Part 927 Pears Grown in Oregon and Washington; Assessment Rate Decrease..., an interim rule that decreased the assessment rate established for the Processed Pear Committee... processed pears grown in Oregon and Washington. The Committee recommended the assessment rate decrease...
Tomlinson, Sean
2016-04-01
The calculation and comparison of physiological characteristics of thermoregulation has provided insight into patterns of ecology and evolution for over half a century. Thermoregulation has typically been explored using linear techniques; I explore the application of non-linear scaling to more accurately calculate and compare characteristics and thresholds of thermoregulation, including the basal metabolic rate (BMR), peak metabolic rate (PMR) and the lower (Tlc) and upper (Tuc) critical limits to the thermo-neutral zone (TNZ) for Australian rodents. An exponentially-modified logistic function accurately characterised the response of metabolic rate to ambient temperature, while evaporative water loss was accurately characterised by a Michaelis-Menten function. When these functions were used to resolve unique parameters for the nine species studied here, the estimates of BMR and TNZ were consistent with the previously published estimates. The approach resolved differences in rates of metabolism and water loss between subfamilies of Australian rodents that haven't been quantified before. I suggest that non-linear scaling is not only more effective than the established segmented linear techniques, but also is more objective. This approach may allow broader and more flexible comparison of characteristics of thermoregulation, but it needs testing with a broader array of taxa than those used here.
Energy Technology Data Exchange (ETDEWEB)
Sayyar-Rodsari, Bijan; Schweiger, Carl; Hartman, Eric
2007-10-07
The difficult problems being tackled in the accelerator community are those that are nonlinear, substantially unmodeled, and vary over time. Such problems are ideal candidates for model-based optimization and control if representative models of the problem can be developed that capture the necessary mathematical relations and remain valid throughout the operation region of the system, and through variations in system dynamics. The goal of this proposal is to develop the methodology and the algorithms for building high-fidelity mathematical representations of complex nonlinear systems via constrained training of combined first-principles and neural network models.
2015-01-01
From the Back Cover: The emphasis throughout the present volume is on the practical application of theoretical mathematical models helping to unravel the underlying mechanisms involved in processes from mathematical physics and biosciences. It has been conceived as a unique collection of abstract methods dealing especially with nonlinear partial differential equations (either stationary or evolutionary) that are applied to understand concrete processes involving some important applications re...
Non-linear dynamics of inlet film thickness during unsteady rolling process
Fu, Kuo; Zang, Yong; Gao, Zhiying; Qin, Qin; Wu, Diping
2016-05-01
The inlet film thickness directly affects film and stress distribution of rolling interfaces. Unsteady factors, such as unsteady back tension, may disturb the inlet film thickness. However, the current models of unsteady inlet film thickness lack unsteady disturbance factors and do not take surface topography into consideration. In this paper, based on the hydrodynamic analysis of inlet zone an unsteady rolling film model which concerns the direction of surface topography is built up. Considering the small fluctuation of inlet angle, absolute reduction, reduction ratio, inlet strip thickness and roll radius as the input variables and the fluctuation of inlet film thickness as the output variable, the non-linear relationship between the input and output is discussed. The discussion results show that there is 180° phase difference between the inlet film thickness and the input variables, such as the fluctuant absolute reduction, the fluctuant reduction ratio and non-uniform inlet strip thickness, but there is no phase difference between unsteady roll radius and the output. The inlet angle, the steady roll radius and the direction of surface topography have significant influence on the fluctuant amplitude of unsteady inlet film thickness. This study proposes an analysis method for unsteady inlet film thickness which takes surface topography and new disturbance factors into consideration.
Lei, Dangyuan
2016-09-01
In the first part of this talk, I will show our experimental investigation on the linear and nonlinear optical properties of metal film-coupled nanosphere monomers and dimers both with nanometric gaps. We have developed a new methodology - polarization resolved spectral decomposition and color decoding to "visualizing" unambiguously the spectral and radiation properties of the complex plasmonic gap modes in these hybrid nanostructures. Single-particle spectroscopic measurements indicate that these hybrid nanostructures can simultaneously enhance several nonlinear optical processes, such as second harmonic generation, two-photon absorption induced luminescence, and hyper-Raman scattering. In the second part, I will show how the polarization state of the emissions from sub-10 nm upconversion nanocrystals (UCNCs) can be modulated when they form a hybrid complex with a gold nanorod (GNR). Our single-particle scattering experiments expose how an interplay between excitation polarization and GNR orientation gives rise to an extraordinary polarized nature of the upconversion emissions from an individual hybrid nanostructure. We support our results by numerical simulations and, using Förster resonance energy transfer theory, we uncover how an overlap between the UCNC emission and GNR extinction bands as well as the mutual orientation between emission and plasmonic dipoles jointly determine the polarization state of the UC emissions.
Prasad, Paras N.
2017-02-01
Chiral control of nonlinear optical functions holds a great promise for a wide range of applications including optical signal processing, bio-sensing and chiral bio-imaging. In chiral polyfluorene thin films, we demonstrated extremely large chiral nonlinearity. The physics of manipulating excitation dynamics for photon transformation will be discussed, along with nanochemistry control of upconversion in hierarchically built organic chromophore coupled-core-multiple shell nanostructures which enable introduce new, organic-inorganic energy transfer routes for broadband light harvesting and increased upconversion efficiency via multistep cascaded energy transfer. We are pursuing the applications of photon conversion technology in IR harvesting for photovoltaics, high contrast bioimaging, photoacoustic imaging, photodynamic therapy, and optogenetics. An important application is in Brain research and Neurophotonics for functional mapping and modulation of brain activities. Another new direction pursued is magnetic field control of light in in a chiral polymer nanocomposite to achieve large magneto-optic coefficient which can enable sensing of extremely weak magnetic field due to brain waves. Finally, we will consider the thought provoking concept of utilizing photons to quantify, through magneto-optics, and augment - through nanoptogenetics, the cognitive states, thus paving the path way to a quantified human paradigm.
Shortell, Matthew P; Jaatinen, Esa A; Chang, Jin; Waclawik, Eric R
2014-03-24
We report a new approach that uses the single beam Z-scan technique, to discriminate between excited state absorption (ESA) and two and three photon nonlinear absorption. By measuring the apparent delay or advance of the pulse in reaching the detector, the nonlinear absorption can be unambiguously identified as either instantaneous or transient. The simple method does not require a large range of input fluences or sophisticated pulse-probe experimental apparatus. The technique is easily extended to any absorption process dependent on pulse width and to nonlinear refraction measurements. We demonstrate in particular, that the large nonlinear absorption in ZnO nanocones when exposed to nanosecond 532 nm pulses, is due mostly to ESA, not pure two-photon absorption.
Kaulakys, B.; Alaburda, M.; Ruseckas, J.
2016-05-01
A well-known fact in the financial markets is the so-called ‘inverse cubic law’ of the cumulative distributions of the long-range memory fluctuations of market indicators such as a number of events of trades, trading volume and the logarithmic price change. We propose the nonlinear stochastic differential equation (SDE) giving both the power-law behavior of the power spectral density and the long-range dependent inverse cubic law of the cumulative distribution. This is achieved using the suggestion that when the market evolves from calm to violent behavior there is a decrease of the delay time of multiplicative feedback of the system in comparison to the driving noise correlation time. This results in a transition from the Itô to the Stratonovich sense of the SDE and yields a long-range memory process.
Radu, A.; Duque, C. A.
2015-08-01
The conduction subband structure of a triangular cross-section GaAs/AlGaAs quantum well wire under intense laser field is theoretically investigated by taking into account a finite confining potential. The calculation of the subband energy levels is based on a two-dimensional finite element method within the effective mass approximation. It is shown that a transversally polarized laser field non-uniformly shifts the subband energy levels and could be used for tuning the intersubband transitions and altering the related optical susceptibilities. We found that the non-resonant laser field allows the magnification and the red- or blueshift of the third-order non-linear susceptibility peaks for particular polarizations of the pump light and proper laser parameter values. The effects of the laser dressing field on the intersubband third harmonic generation and quadratic electro-optical process are discussed.
Vergnole, Sébastien; Lévesque, Daniel; Lamouche, Guy
2010-05-10
We evaluate various signal processing methods to handle the non-linearity in wavenumber space exhibited by most laser sources for swept-source optical coherence tomography. The following methods are compared for the same set of experimental data: non-uniform discrete Fourier transforms with Vandermonde matrix or with Lomb periodogram, resampling with linear interpolation or spline interpolation prior to fast-Fourier transform (FFT), and resampling with convolution prior to FFT. By selecting an optimized Kaiser-Bessel window to perform the convolution, we show that convolution followed by FFT is the most efficient method. It allows small fractional oversampling factor between 1 and 2, thus a minimal computational time, while retaining an excellent image quality. (c) 2010 Optical Society of America.
Hutka, Stefanie; Bidelman, Gavin M; Moreno, Sylvain
2013-12-30
There is convincing empirical evidence for bidirectional transfer between music and language, such that experience in either domain can improve mental processes required by the other. This music-language relationship has been studied using linear models (e.g., comparing mean neural activity) that conceptualize brain activity as a static entity. The linear approach limits how we can understand the brain's processing of music and language because the brain is a nonlinear system. Furthermore, there is evidence that the networks supporting music and language processing interact in a nonlinear manner. We therefore posit that the neural processing and transfer between the domains of language and music are best viewed through the lens of a nonlinear framework. Nonlinear analysis of neurophysiological activity may yield new insight into the commonalities, differences, and bidirectionality between these two cognitive domains not measurable in the local output of a cortical patch. We thus propose a novel application of brain signal variability (BSV) analysis, based on mutual information and signal entropy, to better understand the bidirectionality of music-to-language transfer in the context of a nonlinear framework. This approach will extend current methods by offering a nuanced, network-level understanding of the brain complexity involved in music-language transfer.
Ho, K. K.; Moody, G. B.; Peng, C. K.; Mietus, J. E.; Larson, M. G.; Levy, D.; Goldberger, A. L.
1997-01-01
BACKGROUND: Despite much recent interest in quantification of heart rate variability (HRV), the prognostic value of conventional measures of HRV and of newer indices based on nonlinear dynamics is not universally accepted. METHODS AND RESULTS: We have designed algorithms for analyzing ambulatory ECG recordings and measuring HRV without human intervention, using robust methods for obtaining time-domain measures (mean and SD of heart rate), frequency-domain measures (power in the bands of 0.001 to 0.01 Hz [VLF], 0.01 to 0.15 Hz [LF], and 0.15 to 0.5 Hz [HF] and total spectral power [TP] over all three of these bands), and measures based on nonlinear dynamics (approximate entropy [ApEn], a measure of complexity, and detrended fluctuation analysis [DFA], a measure of long-term correlations). The study population consisted of chronic congestive heart failure (CHF) case patients and sex- and age-matched control subjects in the Framingham Heart Study. After exclusion of technically inadequate studies and those with atrial fibrillation, we used these algorithms to study HRV in 2-hour ambulatory ECG recordings of 69 participants (mean age, 71.7+/-8.1 years). By use of separate Cox proportional-hazards models, the conventional measures SD (Psurvival over a mean follow-up period of 1.9 years; other measures, including ApEn (P>.3), were not. In multivariable models, DFA was of borderline predictive significance (P=.06) after adjustment for the diagnosis of CHF and SD. CONCLUSIONS: These results demonstrate that HRV analysis of ambulatory ECG recordings based on fully automated methods can have prognostic value in a population-based study and that nonlinear HRV indices may contribute prognostic value to complement traditional HRV measures.
Bagheri, Abdollah
The in-situ measurement of thermal stress in civil and mechanical structures may prevent structural anomalies such as unexpected buckling. In the first half of the dissertation, we present a study where highly nonlinear solitary waves (HNSWs) were utilized to measure axial stress in slender beams. HNSWs are compact non-dispersive waves that can form and travel in nonlinear systems such as one-dimensional chains of particles. The effect of the axial stress acting in a beam on the propagation of HNSWs was studied. We found that certain features of the solitary waves enable the measurement of the stress. In general, most guided ultrasonic waves (GUWs)-based health monitoring approaches for structural waveguides are based on the comparison of testing data to baseline data. In the second half of the dissertation, we present a study where some baseline-free signal processing algorithms were presented and applied to numerical and experimental data for the structural health monitoring (SHM) of underwater or dry structures. The algorithms are based on one or more of the following: continuous wavelet transform, empirical mode decomposition, Hilbert transform, competitive optimization algorithm, probabilistic methods. Moreover, experimental data were also processed to extract some features from the time, frequency, and joint time-frequency domains. These features were then fed to a supervised learning algorithm based on artificial neural networks to classify the types of defect. The methods were validated using the numerical model of a plate and a pipe, and the experimental study of a plate in water. In experiment, the propagation of ultrasonic waves was induced by means of laser pulses or transducer and detected with an array of immersion transducers. The results demonstrated that the algorithms are effective, robust against noise, and able to localize and classify the damage.
Lee, Kwang Jo; Liu, Sheng; Gallo, Katia; Petropoulos, Periklis; Richardson, David J
2011-04-25
We report a systematic and comparative study of the acceptance bandwidths of two cascaded quadratic nonlinear processes in periodically poled lithium niobate waveguides, namely cascaded second-harmonic generation and difference-frequency generation (cSHG/DFG) and cascaded sum-frequency generation and difference-frequency generation (cSFG/DFG). We first theoretically and experimentally study the acceptance bandwidths of both the individual second-harmonic generation (SHG) and sum-frequency generation (SFG) processes in the continuous wave (CW) and pulsed-pump regimes. Our results show that the SHG bandwidth is approximately half that of the SFG process in the CW regime, whereas the SHG acceptance bandwidth can approach the CW SFG bandwidth limit when pulsed-pump is used. As a consequence we conclude that the tuning bandwidths of both cascaded processes should be similar in the pulsed pump regime once the pump pulse bandwidths approach that of SFG (i.e. the cSHG/DFG bandwidth is not limited by the CW SHG bandwidth). We confirm that this is the case experimentally.
Biomass is the main driver of changes in ecosystem process rates during tropical forest succession
Lohbeck, M.W.M.; Poorter, L.; Martinez-Ramos, M.; Bongers, F.
2015-01-01
Over half of the world's forests are disturbed, and the rate at which ecosystem processes recover after disturbance is important for the services these forests can provide. We analyze the drivers' underlying changes in rates of key ecosystem processes (biomass productivity, litter productivity, actu
Biomass is the main driver of changes in ecosystem process rates during tropical forest succession
Lohbeck, M.W.M.; Poorter, L.; Martinez-Ramos, M.; Bongers, F.
2015-01-01
Over half of the world's forests are disturbed, and the rate at which ecosystem processes recover after disturbance is important for the services these forests can provide. We analyze the drivers' underlying changes in rates of key ecosystem processes (biomass productivity, litter productivity,
Fermentation process using specific oxygen uptake rates as a process control
Van Hoek; Pim , Aristidou; Aristos , Rush; Brian
2007-06-19
Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.
Fermentation process using specific oxygen uptake rates as a process control
Energy Technology Data Exchange (ETDEWEB)
Van Hoek, Pim; Aristidou, Aristos; Rush, Brian J.
2016-08-30
Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.
Fermentation process using specific oxygen uptake rates as a process control
Energy Technology Data Exchange (ETDEWEB)
Van Hoek, Pim; Aristidou, Aristos; Rush, Brian
2014-09-09
Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.
On the hazard rate process for imperfectly monitored multi-unit systems
Energy Technology Data Exchange (ETDEWEB)
Barros, A. [Institut des Sciences et Techonologies de l' Information de Troyes (ISTIT-CNRS), Equipe de Modelisation et Surete des Systemes, Universite de Technologie de Troyes (UTT), 12, rue Marie Curie, BP2060, 10010 Troyes cedex (France)]. E-mail: anne.barros@utt.fr; Berenguer, C. [Institut des Sciences et Techonologies de l' Information de Troyes (ISTIT-CNRS), Equipe de Modelisation et Surete des Systemes, Universite de Technologie de Troyes (UTT), 12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Grall, A. [Institut des Sciences et Techonologies de l' Information de Troyes (ISTIT-CNRS), Equipe de Modelisation et Surete des Systemes, Universite de Technologie de Troyes (UTT), 12, rue Marie Curie, BP2060, 10010 Troyes cedex (France)
2005-12-01
The aim of this paper is to present a stochastic model to characterize the failure distribution of multi-unit systems when the current units state is imperfectly monitored. The definition of the hazard rate process existing with perfect monitoring is extended to the realistic case where the units failure time are not always detected (non-detection events). The so defined observed hazard rate process gives a better representation of the system behavior than the classical failure rate calculated without any information on the units state and than the hazard rate process based on perfect monitoring information. The quality of this representation is, however, conditioned by the monotony property of the process. This problem is mainly discussed and illustrated on a practical example (two parallel units). The results obtained motivate the use of the observed hazard rate process to characterize the stochastic behavior of the multi-unit systems and to optimize for example preventive maintenance policies.
Streicher, Jeffrey W; Cox, Christian L; Birchard, Geoffrey F
2012-04-01
Although well documented in vertebrates, correlated changes between metabolic rate and cardiovascular function of insects have rarely been described. Using the very large cockroach species Gromphadorhina portentosa, we examined oxygen consumption and heart rate across a range of body sizes and temperatures. Metabolic rate scaled positively and heart rate negatively with body size, but neither scaled linearly. The response of these two variables to temperature was similar. This correlated response to endogenous (body mass) and exogenous (temperature) variables is likely explained by a mutual dependence on similar metabolic substrate use and/or coupled regulatory pathways. The intraspecific scaling for oxygen consumption rate showed an apparent plateauing at body masses greater than about 3 g. An examination of cuticle mass across all instars revealed isometric scaling with no evidence of an ontogenetic shift towards proportionally larger cuticles. Published oxygen consumption rates of other Blattodea species were also examined and, as in our intraspecific examination of G. portentosa, the scaling relationship was found to be non-linear with a decreasing slope at larger body masses. The decreasing slope at very large body masses in both intraspecific and interspecific comparisons may have important implications for future investigations of the relationship between oxygen transport and maximum body size in insects.
DEFF Research Database (Denmark)
Nielsen, Jesper Kjær; Jensen, Tobias Lindstrøm; Jensen, Jesper Rindom;
2016-01-01
time. Additionally, we show via three common examples how the grid size depends on parameters such as the number of data points or the number of sensors in DOA estimation. We also demonstrate that the computation time can potentially be lowered by several orders of magnitude by combining a coarse grid......In many spectral estimation and array processing problems, the process of finding estimates of model parameters often involves the optimisation of a cost function containing multiple peaks and dips. Such non-convex problems are hard to solve using traditional optimisation algorithms developed...
AUTOMATED SYSTEM OF DATA PROCESSING WITH THE IMPLEMENTATION OF RATING TECHNOLOGY OF TEACHING
Directory of Open Access Journals (Sweden)
О. И. Дзювина
2014-01-01
Full Text Available Rating technology of teaching enables independent and individual work of students, increase their motivation.Purpose: to increase the efficiency of data processing with the implementation of rating technology of teaching.Method: analysis, synthesis,experiment.Results. Developed an automated data processing system for the implementation of rating technology of teaching.Practical implication. Education.Purchase on Elibrary.ru > Buy now
Nonlinear Parasitic Capacitance Modelling of High Voltage Power MOSFETs in Partial SOI Process
DEFF Research Database (Denmark)
Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger
2016-01-01
: off-state, sub-threshold region, and on-state in the linear region. A high voltage power MOSFET is designed in a partial Silicon on Insulator (SOI) process, with the bulk as a separate terminal. 3D plots and contour plots of the capacitances versus bias voltages for the transistor summarize...
Optimization of Nonlinear Figure-of-Merits of Integrated Power MOSFETs in Partial SOI Process
DEFF Research Database (Denmark)
Fan, Lin; Jørgensen, Ivan Harald Holger; Knott, Arnold
2016-01-01
different operating conditions. A systematic analysis of the optimization of these FOMs has not been previously established. The optimization methods are verified on a 100 V power MOSFET implemented in a 0.18 µm partial SOI process. Its FOMs are lowered by 1.3-18.3 times and improved by 22...
Modeling human auditory evoked brainstem responses based on nonlinear cochlear processing
DEFF Research Database (Denmark)
Harte, James; Rønne, Filip Munch; Dau, Torsten
2010-01-01
(ABR) to transient sounds and frequency following responses (FFR) to tones. The model includes important cochlear processing stages (Zilany and Bruce, 2006) such as basilar-membrane (BM) tuning and compression, inner hair-cell (IHC) transduction, and IHC auditory-nerve (AN) synapse adaptation...
Keller, Florian; Feist, Markus; Nirschl, Hermann; Dörfler, Willy
2010-04-01
In this article we study the settling process of a colloidal particle under the influence of a gravitational or centrifugal field in an unbounded electrolyte solution. Since particles in aqueous solutions normally carry a non-zero surface charge, a microscopic electric field develops which alters the sedimentation process compared to an uncharged particle. This process can be mathematically modelled via the Stokes-Poisson-Nernst-Planck system, a system of coupled partial differential equations that have to be solved in an exterior domain. After a dimensional analysis we investigate the influence of the various characteristic dimensionless numbers on the sedimentation velocity. Thereby the linear-response (weak-field) approximation that underpins almost all existing theoretical work on classical electrokinetic phenomena is relaxed, such that no additional assumption on the thickness of the double layer as well as on its displacement is needed. We show that there exists a strong influence of the fluid Reynolds number and the ionic strength on the sedimentation velocity. Further we have developed an asymptotic expansion to describe the limit of small values of the surface potential of a single particle. This expansion incorporates all nonlinear effects and extends the well-known results of Booth (1954) [1] and Ohshima et al. (1984) [2] to higher fluid Reynolds numbers.
Deng, Xiaogang; Wang, Lei
2017-10-07
Traditional kernel principal component analysis (KPCA) based nonlinear process monitoring method may not perform well because its Gaussian distribution assumption is often violated in the real industrial processes. To overcome this deficiency, this paper proposes a modified KPCA method based on double-weighted local outlier factor (DWLOF-KPCA). In order to avoid the assumption of specific data distribution, local outlier factor (LOF) is introduced to construct two LOF-based monitoring statistics, which are used to substitute for the traditional T(2) and SPE statistics, respectively. To provide better online monitoring performance, a double-weighted LOF method is further designed, which assigns the weights for each component to highlight the key components with significant fault information, and uses the moving window to weight the historical statistics for reducing the drastic fluctuations in the monitoring results. Finally, simulations on a numerical example and the Tennessee Eastman (TE) benchmark process are used to demonstrate the superiority of the proposed DWLOF-KPCA method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
The Research on Transient Burning Rate of Solid Propellant by Digital Image Processing
Directory of Open Access Journals (Sweden)
Xin Peng
2016-01-01
Full Text Available In order to obtain the burn rate of the solid propellant that is the important parameter of transient burning, the new method named digital image processing is presented. In the article , the principle of digital image processing is analysed; The burning face of the sample in the each time is located according the image and the coordinates of the burning face is obtained. In experiment the transient burn rate is measured by digital image processing and the accuracy is acceptable.
Institute of Scientific and Technical Information of China (English)
Yan Xia REN
2008-01-01
The global supports of super-Poisson processes and super-random walks with a branching mechanism ψ(z)=z2 and constant branching rate are known to be noncompact. It turns out that, for any spatially dependent branching rate, this property remains true. However, the asymptotic extinction property for these two kinds of superprocesses depends on the decay rate of the branching-rate function at infinity.
Equilibrium theory-based analysis of nonlinear waves in separation processes.
Mazzotti, Marco; Rajendran, Arvind
2013-01-01
Different areas of engineering, particularly separation process technology, deal with one-dimensional, nonstationary processes that under reasonable assumptions, namely negligible dispersion effects and transport resistances, are described by mathematical models consisting of systems of first-order partial differential equations. Their behavior is characterized by continuous or discontinuous composition (or thermal) fronts that propagate along the separation unit. The equilibrium theory (i.e., the approach discussed here to determine the solution to these model equations) predicts this with remarkable accuracy, despite the simplifications and assumptions. Interesting applications are in adsorption, chromatography and ion-exchange, distillation, gas injection, heat storage, sedimentation, precipitation, and dissolution waves. We show how mathematics can enlighten the engineering aspects, and we guide the researcher not only to reach a synthetic understanding of properties of fundamental and applicative interest but also to discover new, unexpected, and fascinating phenomena. The tools presented here are useful to teachers, researchers, and practitioners alike.
Linear and nonlinear post-processing of numerically forecasted surface temperature
Directory of Open Access Journals (Sweden)
M. Casaioli
2003-01-01
Full Text Available In this paper we test different approaches to the statistical post-processing of gridded numerical surface air temperatures (provided by the European Centre for Medium-Range Weather Forecasts onto the temperature measured at surface weather stations located in the Italian region of Puglia. We consider simple post-processing techniques, like correction for altitude, linear regression from different input parameters and Kalman filtering, as well as a neural network training procedure, stabilised (i.e. driven into the absolute minimum of the error function over the learning set by means of a Simulated Annealing method. A comparative analysis of the results shows that the performance with neural networks is the best. It is encouraging for systematic use in meteorological forecast-analysis service operations.
New Robust Nonlinear Controller Design Based on Predictive Control for Industrial Processes
Directory of Open Access Journals (Sweden)
Hossein Esfroghy
2007-12-01
Full Text Available In this paper a new sliding mode controller based on predictive control is used for the first order system, which is a good model for the industrial process. In this method a developed predictive control is used to optimize the sliding mode control including sliding surface and switching function coefficient at every moment. A new smooth function is used to reduce the chattering problems. Simulation results show the high effectiveness of the proposed controller.
Energy Technology Data Exchange (ETDEWEB)
Gorbatov, P.A.; Plyungin, A.V. (Donetskii Politekhnicheskii Institut (USSR))
1990-12-01
Presents calculation methods and mathematical models of dynamic processes that occur in feed systems of cutter loaders with rigid pulling elements. Characteristics of dynamic interactions between driving wheels and the working section of the pulling system are taken into account. Mathematical models are given that describe the dynamic operation of the feed system. A method for calculation of a hydraulic vibration compensating system and its mathematical model is presented. Effectiveness of the vibration compensating system is discussed. 2 refs.
Sadhu, Arunangshu; Sarkar, Somenath
2016-05-01
We report a simple and straightforward approximate analysis to investigate the effect of Kerr type nonlinear optical processes in sub-wavelength diameter step index optical fibers based on Marcuse method in single mode region. Optimum core diameters of such fibers, predicted by us, together with relevant core nonlinearity coefficient and effective area are seen to be compatible with the analytical values indicating the validity of this novel application of the elegant approximate method. However, the corresponding values, obtained by earlier variational method, show larger discrepancy with analytical findings in comparison with ours. Also, maximum enhancement of nonlinear processes within single mode region, confirming almost the analytical method, assures less diffraction. Formulations, coupled with simplicity and novelty of the present analysis, should find wide use by system users and experimentalists in this emerging area.
Transient simulation of regression rate on thrust regulation process in hybrid rocket motor
Directory of Open Access Journals (Sweden)
Tian Hui
2014-12-01
Full Text Available The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas. Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB (hydroxyl-terminated polybutadiene hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.
Transient simulation of regression rate on thrust regulation process in hybrid rocket motor
Institute of Scientific and Technical Information of China (English)
Tian Hui; Li Yijie; Zeng Peng
2014-01-01
The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas. Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB (hydroxyl-terminated polybutadiene) hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.
Analog CMOS Nonlinear Cells and Their Applications in VLSI Signal and Information Processing
Khachab, Nabil Ibrahim
1990-01-01
The development of reconfigurable analog CMOS building blocks and their applications in analog VLSI is discussed and introduced in much the same way a logic gate is used in digital VLSI. They simultaneously achieve four -quadrant multiplication and division. These applications include multiplication, signal squaring, division, signal inversion, amplitude modulation. New all MOS implementations of the Hopfield like neural networks are developed by using the new cells. In addition new and novel techniques for sensor linearization and for MOSFET-C programmable-Q and omega_{n} filters are introduced. The new designs are simple, versatile, programmable and make effective use of analog CAD tools. Moreover, they are easily extendable to other technologies such as GaAs and BiCMOS. The objective of these designs is to achieve reduction in Silicon area and power consumption and reduce the interconnections between cells. It is also sought to provide a robust design that is CAD-compatible and make effective use of the standard cell library approach. This will offer more versatility and flexibility for analog signal processing systems and neural networks. Some of these new cells and a 3-neuron neural system are fabricated in a 2mum CMOS process. Experimental results of these circuits verify the validity of this new design approach.
3D modelling of non-linear visco-elasto-plastic crustal and lithospheric processes using LaMEM
Popov, Anton; Kaus, Boris
2016-04-01
LaMEM (Lithosphere and Mantle Evolution Model) is a three-dimensional thermo-mechanical numerical code to simulate crustal and lithospheric deformation. The code is based on a staggered finite difference (FDSTAG) discretization in space, which is a stable and very efficient technique to solve the (nearly) incompressible Stokes equations that does not suffer from spurious pressure modes or artificial compressibility (a typical feature of low-order finite element techniques). Higher order finite element methods are more accurate than FDSTAG methods under idealized test cases where the jump in viscosity is exactly aligned with the boundaries of the elements. Yet, geodynamically more realistic cases involve evolving subduction zones, nonlinear rheologies or localized plastic shear bands. In these cases, the viscosity pattern evolves spontaneously during a simulation or even during nonlinear iterations, and the advantages of higher order methods disappear and they all converge with approximately first order accuracy, similar to that of FDSTAG [1]. Yet, since FDSTAG methods have considerably less degrees of freedom than quadratic finite element methods, they require about an order of magnitude less memory for the same number of nodes in 3D which also implies that every matrix-vector multiplication is significantly faster. LaMEM is build on top of the PETSc library and uses the particle-in-cell technique to track material properties, history variables which makes it straightforward to incorporate effects like phase changes or chemistry. An internal free surface is present, together with (simple) erosion and sedimentation processes, and a number of methods are available to import complex geometries into the code (e.g, http://geomio.bitbucket.org). Customized Galerkin coupled geometric multigrid preconditioners are implemented which resulted in a good parallel scalability of the code (we have tested LaMEM on 458'752 cores [2]). Yet, the drawback of using FDSTAG
Institute of Scientific and Technical Information of China (English)
Hong-xia Xi; Zhong Li; Zhao-xi Liang
2001-01-01
A new organic/inorganic hybrid nonlinear optical (NLO) material was developed by the sol-gel process of an alkoxysilane dye with tetraethoxysilane. A NLO moiety based on 4-nitro-4′-hydroxy azobenzene was covalently bonded to the triethoxysilane derivative, i.e. γ-isocyanatopropyl triethoxysilane. The preparation process and properties of the sol-gel derived NLO polymer were studied and characterized by SEM, FTIR, 1H-NMR, UV-Vis, DSC and second harmonic generation (SHG) measurement. The results indicated that the chemical bonding of the chromophores to the inorganic SiO2 networks induces Iow dipole alignment relaxation and preferable orientational stability. The SHG measurements also showed that the bonded polymer film containing 75 wt% of the akoxysilane dye has a high electro-optic coefficient (r33) of7. 1 pm/V at 1.1 μm wavelength, and exhibit good SHG stability, the r33 values can maintain about 92.7% of its initial value at room temperature for 90 days, and can maintain about 59.3% at 100℃ for 300 min.``
Frenkel, M. M.; LaVigne, M.; Miller, H. R.; Hill, T. M.; McNichol, A.; Gaylord, M. Lardie
2017-07-01
Bamboo corals, long-lived cold water gorgonin octocorals, offer unique paleoceanographic archives of the intermediate ocean. These Isididae corals are characterized by alternating gorgonin nodes and high Mg-calcite internodes, which synchronously extend radially. Bamboo coral calcite internodes have been utilized to obtain geochemical proxy data, however, growth rate uncertainty has made it difficult to construct precise chronologies for these corals. Previous studies have relied upon a single tie point from records of the anthropogenic Δ14C bomb spike preserved in the gorgonin nodes of live-collected corals to calculate a mean radial extension rate for the outer 50 years of skeletal growth. Bamboo coral chronologies are typically constructed by applying this mean extension rate to the entire coral record, assuming constant radial extension with coral age. In this study, we aim to test this underlying assumption by analyzing the organic nodes of six California margin bamboo corals at high enough resolution (coral collection date (2007.5) for four samples. Radial extension rates between tie points ranged from 10 to 204 μm/year, with a decrease in growth rate evident between the 1957-1970 and 1970-2007.5 periods for all four corals. A negative correlation between growth rate and coral radius (r =-0.7; p=0.04) was determined for multiple bamboo coral taxa and individuals from the California margin, demonstrating a decline in radial extension rate with specimen age and size. To provide a mechanistic basis for these observations, a simple mathematical model was developed based on the assumption of a constant increase in circular cross sectional area with time to quantify this decline in radial extension rate with coral size between chronological tie points. Applying the area-based model to our Δ14C bomb spike time series from individual corals improves chronology accuracy for all live-collected corals with complete Δ14C bomb spikes. Hence, this study provides
The un-making of a method: From rating scales to the study of psychological processes
DEFF Research Database (Denmark)
Rosenbaum, Philip J.; Valsiner, Jaan
2011-01-01
Rating scales are standard instruments in psychology. They force the research participant to provide a numerical estimate of an assumed “degree” of some characteristic along a linear scale. We prove that such numerical estimates are artifacts based on unknown psychological processes that are used...... in the making of a rating. Psychology’s current use of rating scales entails reliance upon unexplored and abbreviated introspection. It superimposes upon the rater the use of real numbers for the subjective construction of the ratings. The axiomatic superimposition of the notion of “degree” of subjective...... estimates by the rating task overlooks the qualitative (structural) relation between the implied opposites. We propose the reconstruction of the rating tasks into a method that accesses the process of meaning construction by the rater. When the rater faces a rating task, a field of meanings is constructed...
Ganeev, R. A.
2017-08-01
The nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range became a versatile tool for the analysis of the optical, structural and morphological properties of matter. The carbon-contained materials have shown the advanced properties among other studied species, which allowed both the definition of the role of structural properties on the nonlinear optical response and the analysis of the fundamental features of carbon as the attractive material for generation of coherent short-wavelength radiation. We review the studies of the high-order harmonic generation by focusing ultrashort pulses into the plasmas produced during laser ablation of various organic compounds. We discuss the role of ionic transitions of ablated carbon-containing molecules on the harmonic yield. We also show the similarities and distinctions of the harmonic and plasma spectra of organic compounds and graphite. We discuss the studies of the generation of harmonics up to the 27th order (λ = 29.9 nm) of 806 nm radiation in the boron carbide plasma and analyze the advantages and disadvantages of this target compared with the ingredients comprising B4C (solid boron and graphite) by comparing plasma emission and harmonic spectra from three species. We also show that the coincidence of harmonic and plasma emission wavelengths in most cases does not cause the enhancement or decrease of the conversion efficiency of this harmonic.
Ebrahimi, Farideh; Setarehdan, Seyed-Kamaledin; Ayala-Moyeda, Jose; Nazeran, Homer
2013-10-01
The conventional method for sleep staging is to analyze polysomnograms (PSGs) recorded in a sleep lab. The electroencephalogram (EEG) is one of the most important signals in PSGs but recording and analysis of this signal presents a number of technical challenges, especially at home. Instead, electrocardiograms (ECGs) are much easier to record and may offer an attractive alternative for home sleep monitoring. The heart rate variability (HRV) signal proves suitable for automatic sleep staging. Thirty PSGs from the Sleep Heart Health Study (SHHS) database were used. Three feature sets were extracted from 5- and 0.5-min HRV segments: time-domain features, nonlinear-dynamics features and time-frequency features. The latter was achieved by using empirical mode decomposition (EMD) and discrete wavelet transform (DWT) methods. Normalized energies in important frequency bands of HRV signals were computed using time-frequency methods. ANOVA and t-test were used for statistical evaluations. Automatic sleep staging was based on HRV signal features. The ANOVA followed by a post hoc Bonferroni was used for individual feature assessment. Most features were beneficial for sleep staging. A t-test was used to compare the means of extracted features in 5- and 0.5-min HRV segments. The results showed that the extracted features means were statistically similar for a small number of features. A separability measure showed that time-frequency features, especially EMD features, had larger separation than others. There was not a sizable difference in separability of linear features between 5- and 0.5-min HRV segments but separability of nonlinear features, especially EMD features, decreased in 0.5-min HRV segments. HRV signal features were classified by linear discriminant (LD) and quadratic discriminant (QD) methods. Classification results based on features from 5-min segments surpassed those obtained from 0.5-min segments. The best result was obtained from features using 5-min HRV
Multi input single output model predictive control of non-linear bio-polymerization process
Energy Technology Data Exchange (ETDEWEB)
Arumugasamy, Senthil Kumar; Ahmad, Z. [School of Chemical Engineering, Univerisiti Sains Malaysia, Engineering Campus, Seri Ampangan,14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia)
2015-05-15
This paper focuses on Multi Input Single Output (MISO) Model Predictive Control of bio-polymerization process in which mechanistic model is developed and linked with the feedforward neural network model to obtain a hybrid model (Mechanistic-FANN) of lipase-catalyzed ring-opening polymerization of ε-caprolactone (ε-CL) for Poly (ε-caprolactone) production. In this research, state space model was used, in which the input to the model were the reactor temperatures and reactor impeller speeds and the output were the molecular weight of polymer (M{sub n}) and polymer polydispersity index. State space model for MISO created using System identification tool box of Matlab™. This state space model is used in MISO MPC. Model predictive control (MPC) has been applied to predict the molecular weight of the biopolymer and consequently control the molecular weight of biopolymer. The result shows that MPC is able to track reference trajectory and give optimum movement of manipulated variable.
All-Optical Signal processing using Highly Nonlinear Photonic Crystal Fiber
DEFF Research Database (Denmark)
Andersen, Peter Andreas
2006-01-01
The use of HNL-PCF in optical communication systems has been investigated in this thesis. The investigation has been done with respect to the future of telecommunications in an all-optical system. The PCFs used have all been used for all-optical signal processing as part of an optical component...... and the possibility of large differences between the refractive indices of the core and the cladding by using air-holes, makes PCFs suited for custom made components. By testing a HNL-PCF as a medium for supercontinuum generation at various dispersion values and at the same time using that supercontinuum...... of modulation format of the signal. The modulation format is also dependent on transmission in the optical system and dependent on the pulse source used to generate the supercontinuum. It is believed that by satisfying strict demands on the pulse sources and the fiber design, could the use of a supercontinuum...
Fuhry, Martin; Krivodonova, Lilia
2016-01-01
We present a novel implementation of the modal discontinuous Galerkin (DG) method for hyperbolic conservation laws in two dimensions on graphics processing units (GPUs) using NVIDIA's Compute Unified Device Architecture (CUDA). Both flexible and highly accurate, DG methods accommodate parallel architectures well as their discontinuous nature produces element-local approximations. High performance scientific computing suits GPUs well, as these powerful, massively parallel, cost-effective devices have recently included support for double-precision floating point numbers. Computed examples for Euler equations over unstructured triangle meshes demonstrate the effectiveness of our implementation on an NVIDIA GTX 580 device. Profiling of our method reveals performance comparable to an existing nodal DG-GPU implementation for linear problems.
Self-Organized Criticality in Astrophysics The Statistics of Nonlinear Processes in the Universe
Aschwanden, Markus
2011-01-01
The concept of ‘self-organized criticality’ (SOC) has been applied to a variety of problems, ranging from population growth and traffic jams to earthquakes, landslides and forest fires. The technique is now being applied to a wide range of phenomena in astrophysics, such as planetary magnetospheres, solar flares, cataclysmic variable stars, accretion disks, black holes and gamma-ray bursts, and also to phenomena in galactic physics and cosmology. Self-organized Criticality in Astrophysics introduces the concept of SOC and shows that, due to its universality and ubiquity, it is a law of nature. The theoretical framework and specific physical models are described, together with a range of applications in various aspects of astrophyics. The mathematical techniques, including the statistics of random processes, time series analysis, time scale and waiting time distributions, are presented and the results are applied to specific observations of astrophysical phenomena.
Institute of Scientific and Technical Information of China (English)
郭树敏; 李学志
2015-01-01
研究具有非线性感染率的传统数学模型,通过对模型的稳定性分析得到了保证染病平衡态和无病平衡态的全局稳定性所需要的参数条件,并进行了数值模拟.%It is well known that the mathematical models provide very significant information for the research of human immunodeficiency HIV-1and HCV. However, the infection rate of nearly all mathematical models is lin-ear which shows the simple interaction between the T cells and the viral particles. It has practical significance to study a traditional mathematical model with nonlinear infection rate. It obtained some sufficient conditions on the parameters for the global stability of the infected equilibrium state, and the infection-free equilibrium state are given. Numerical simulations are presented to illustrate the results.
D.E. Allen (David); M.J. McAleer (Michael); S. Peiris (Shelton); A.K. Singh (Abhay)
2015-01-01
textabstractThis paper features an analysis of major currency exchange rate movements in relation to the US dollar, as constituted in US dollar terms. Euro, British pound, Chinese yuan, and Japanese yen are modelled using a variety of non- linear models, including smooth transition regression models
Salis, Lucia; Lof, Marjolein; van Asch, Margriet; Visser, Marcel E.
2016-01-01
Understanding the relationship between an insect's developmental rate and temperature is crucial to forecast insect phenology under climate change. In the winter moth Operophtera brumata timing of egg-hatching has severe fitness consequences on growth and reproduction as egg-hatching has to match bu
DEFF Research Database (Denmark)
Tanev, George; Saadi, Dorthe Bodholt; Hoppe, Karsten
2014-01-01
features from electrocardiograms (ECG) acquired by the wireless wearable ePatch® recorder. The highest recognition rates were acquired for the neutral stage (90%), the acute stress stage (80%) and the baseline stage (80%) by sample entropy, detrended fluctuation analysis and normalized high frequency...
Ultrafast and nonlinear optical characterization of optical limiting processes in fullerenes
Energy Technology Data Exchange (ETDEWEB)
Kohlman, R.; Klimov, V.; Shi, X. [and others
1997-10-01
The authors present recent results of broadband femotosecond (fs) transient absorption (TA) and broadband nanosecond (ns) optical limiting (OL) studies of C{sub 60} and derivatized C{sub 60}. Improvements in measurement techniques for fs TA spectra provide sensitivity to 10{sup {minus}5} in differential transmission, allowing detailed comparison of excited-state spectra with established energy level diagrams, as well as comparison of the ratio of triplet to singlet excited-state absorption cross sections from TA spectra with those obtained by modeling time transients at different wavelengths. For derivatized fullerenes, which provide enhanced solubility and a ground-state absorption extended into the infrared compared with C{sub 60} there is no spectral region where the triplet absorption cross section dominates the singlet as strongly as demonstrating broadband limiting in all 6, 6 mono-adducts and neat C{sub 60}. The authors report new approaches to processing sol-gel encapsulated fullerenes to improve the OL performance of solid-state materials to approach the response of solution limiters.
Beta decay rates for nuclei with 115 < < 140 for r-process nucleosynthesis
Indian Academy of Sciences (India)
Kamales Kar; Soumya Chakravarti; V R Manfredi
2006-08-01
For r-process nucleosynthesis the -decay rates for a number of neutron-rich intermediate heavy nuclei are calculated. The model for the -strength function is able to reproduce the observed half-lives quite well.
Borghesani, A F; Carugno, G
2013-01-01
We report measurements of microwave (RF) generation in the centimeter band accomplished by irradiating a nonlinear KTiOPO$_4$ (KTP) crystal with a home-made, infrared laser at $1064\\,$nm as a result of optical rectification (OR). The laser delivers pulse trains of duration up to $1\\,\\mu$s. Each train consists of several high-intensity pulses at an adjustable repetition rate of approximately $ 4.6\\,$GHz. The duration of the generated RF pulses is determined by that of the pulse trains. We have investigated both microwave- and second harmonic (SHG) generation as a function of the laser intensity and of the orientation of the laser polarization with respect to the crystallographic axes of KTP.
Pando, V.; García-Laguna, J.; San-José, L. A.
2012-11-01
In this article, we integrate a non-linear holding cost with a stock-dependent demand rate in a maximising profit per unit time model, extending several inventory models studied by other authors. After giving the mathematical formulation of the inventory system, we prove the existence and uniqueness of the optimal policy. Relying on this result, we can obtain the optimal solution using different numerical algorithms. Moreover, we provide a necessary and sufficient condition to determine whether a system is profitable, and we establish a rule to check when a given order quantity is the optimal lot size of the inventory model. The results are illustrated through numerical examples and the sensitivity of the optimal solution with respect to changes in some values of the parameters is assessed.
49 CFR Appendix B to Part 385 - Explanation of Safety Rating Process
2010-10-01
... SAFETY FITNESS PROCEDURES Pt. 385, App. B Appendix B to Part 385—Explanation of Safety Rating Process (a..., including if applicable its operations in Canada and/or Mexico. I. Source of Data for Rating Methodology (a... commerce or within Canada or Mexico (if the motor carrier also operates in the United States) that results...
Transient kinetics and rate limiting steps for the processive cellobiohydrolase Cel7A
DEFF Research Database (Denmark)
Cruys-Bagger, Nicolaj; Hirosuke, Tatsumi; Robin Ren, Guilin
2013-01-01
as substrate. Analysis of the pre-steady state regime allowed delineation rate constants for both fast and slow steps in the enzymatic cycle and assessment of how these constants influenced the rate of hydrolysis at quasi-steady state. Processive movement on the cellulose strand advanced with characteristic...
Leslie, Thomas M.
1995-01-01
Data obtained from the electric field induced second harmonic generation (EFISH) and Kurtz Powder Methods will be provided to MSFC for further refinement of their method. A theoretical model for predicting the second-order nonlinearities of organic salts is being worked on. Another task is the synthesis of a number of salts with various counterions. Several salts with promising SHG activities and new salts will be tested for the presence of two crystalline forms. The materials will be recrystallized from dry and wet solvents and compared for SHG efficiency. Salts that have a high SHG efficiency and no tendency to form hydrates will be documented. The synthesis of these materials are included in this report. A third task involves method to aid in the growth of large, high quality single crystals by solution processes. These crystals will be characterized for their applicability in the fabrication of devices that will be incorporated into optical computers in future programs. Single crystals of optimum quality may be obtained by crystal growth in low-gravity. The final task is the design of a temperature lowering single crystal growth apparatus for ground based work. At least one prototype will be built.
Weak interaction rates for Kr and Sr waiting-point nuclei under rp-process conditions
Energy Technology Data Exchange (ETDEWEB)
Sarriguren, P., E-mail: sarriguren@iem.cfmac.csic.e [Instituto de Estructura de la Materia, CSIC, Serrano 123, E-28006 Madrid (Spain)
2009-10-12
Weak interaction rates are studied in neutron deficient Kr and Sr waiting-point isotopes in ranges of densities and temperatures relevant for the rp process. The nuclear structure is described within a microscopic model (deformed QRPA) that reproduces not only the half-lives but also the Gamow-Teller strength distributions recently measured. The various sensitivities of the decay rates to both density and temperature are discussed. Continuum electron capture is shown to contribute significantly to the weak rates at rp-process conditions.
Individual Differences in Base Rate Neglect: A Fuzzy Processing Preference Index
Wolfe, Christopher R.; Fisher, Christopher R.
2013-01-01
Little is known about individual differences in integrating numeric base-rates and qualitative text in making probability judgments. Fuzzy-Trace Theory predicts a preference for fuzzy processing. We conducted six studies to develop the FPPI, a reliable and valid instrument assessing individual differences in this fuzzy processing preference. It…
Heath, J.P.; Gilchrist, H.G.; Ydenberg, R.C.
2010-01-01
To maximize fitness, animals must respond to a variety of processes that operate at different rates or timescales. Appropriate decisions could therefore involve complex interactions among these processes. For example, eiders wintering in the arctic sea ice must consider locomotion and physiology of
Heath, J.P.; Gilchrist, H.G.; Ydenberg, R.C.
2010-01-01
To maximize fitness, animals must respond to a variety of processes that operate at different rates or timescales. Appropriate decisions could therefore involve complex interactions among these processes. For example, eiders wintering in the arctic sea ice must consider locomotion and physiology of
L2-Algebraic Decay Rate for Transient Birth-Death Processes
Institute of Scientific and Technical Information of China (English)
Lijuan CHENG; Yingzhe WANG
2012-01-01
This paper is a continuation of the study of the algebraic speed for Markov processes.The authors concentrate on algebraic decay rate for the transient birth-death processes.According to the classification of the boundaries,a series of the sufficient conditions for algebraic decay is presented.To illustrate the power of the results,some examples are included.
Speech rate effects on the processing of conversational speech across the adult life span.
Koch, Xaver; Janse, Esther
2016-04-01
This study investigates the effect of speech rate on spoken word recognition across the adult life span. Contrary to previous studies, conversational materials with a natural variation in speech rate were used rather than lab-recorded stimuli that are subsequently artificially time-compressed. It was investigated whether older adults' speech recognition is more adversely affected by increased speech rate compared to younger and middle-aged adults, and which individual listener characteristics (e.g., hearing, fluid cognitive processing ability) predict the size of the speech rate effect on recognition performance. In an eye-tracking experiment, participants indicated with a mouse-click which visually presented words they recognized in a conversational fragment. Click response times, gaze, and pupil size data were analyzed. As expected, click response times and gaze behavior were affected by speech rate, indicating that word recognition is more difficult if speech rate is faster. Contrary to earlier findings, increased speech rate affected the age groups to the same extent. Fluid cognitive processing ability predicted general recognition performance, but did not modulate the speech rate effect. These findings emphasize that earlier results of age by speech rate interactions mainly obtained with artificially speeded materials may not generalize to speech rate variation as encountered in conversational speech.
DEFF Research Database (Denmark)
Scheike, Thomas Harder
2002-01-01
We use the additive risk model of Aalen (Aalen, 1980) as a model for the rate of a counting process. Rather than specifying the intensity, that is the instantaneous probability of an event conditional on the entire history of the relevant covariates and counting processes, we present a model...... for the rate function, i.e., the instantaneous probability of an event conditional on only a selected set of covariates. When the rate function for the counting process is of Aalen form we show that the usual Aalen estimator can be used and gives almost unbiased estimates. The usual martingale based variance...... estimator is incorrect and an alternative estimator should be used. We also consider the semi-parametric version of the Aalen model as a rate model (McKeague and Sasieni, 1994) and show that the standard errors that are computed based on an assumption of intensities are incorrect and give a different...